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Albedo
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**Albedo** (`{{IPAc-en|æ|l|ˈ|b|iː|d|oʊ|audio=LL-Q1860 (eng)-Naomi Persephone Amethyst (NaomiAmethyst)-albedo.wav}}`{=mediawiki} `{{respell|al|BEE|doh}}`{=mediawiki}; `{{etymology|la|albedo|whiteness}}`{=mediawiki}) is the fraction of sunlight that is diffusely reflected by a body. It is measured on a scale from 0 (corresponding to a black body that absorbs all incident radiation) to 1 (corresponding to a body that reflects all incident radiation). *Surface albedo* is defined as the ratio of radiosity *J*~e~ to the irradiance *E*~e~ (flux per unit area) received by a surface. The proportion reflected is not only determined by properties of the surface itself, but also by the spectral and angular distribution of solar radiation reaching the Earth\'s surface. These factors vary with atmospheric composition, geographic location, and time (see position of the Sun).
While directional-hemispherical reflectance factor is calculated for a single angle of incidence (i.e., for a given position of the Sun), albedo is the directional integration of reflectance over all solar angles in a given period. The temporal resolution may range from seconds (as obtained from flux measurements) to daily, monthly, or annual averages.
Unless given for a specific wavelength (spectral albedo), albedo refers to the entire spectrum of solar radiation. Due to measurement constraints, it is often given for the spectrum in which most solar energy reaches the surface (between 0.3 and 3 μm). This spectrum includes visible light (0.4--0.7 μm), which explains why surfaces with a low albedo appear dark (e.g., trees absorb most radiation), whereas surfaces with a high albedo appear bright (e.g., snow reflects most radiation).
Ice--albedo feedback is a positive feedback climate process where a change in the area of ice caps, glaciers, and sea ice alters the albedo and surface temperature of a planet. Ice is very reflective, therefore it reflects far more solar energy back to space than the other types of land area or open water. Ice--albedo feedback plays an important role in global climate change. Albedo is an important concept in climate science.
## Terrestrial albedo {#terrestrial_albedo}
+------------------+---------------------+
| Surface | Typical\ |
| | albedo |
+==================+=====================+
| Fresh asphalt | 0.04{{cite web |
+------------------+---------------------+
| Open ocean | 0.06 |
+------------------+---------------------+
| Worn asphalt | 0.12 |
+------------------+---------------------+
| Conifer forest,\ | 0.08,{{Cite journal |
| summer | |
+------------------+---------------------+
| Deciduous forest | 0.15 to 0.18 |
+------------------+---------------------+
| Bare soil | 0.17{{Cite book |
+------------------+---------------------+
| Green grass | 0.25 |
+------------------+---------------------+
| Desert sand | 0.40{{Cite book |
+------------------+---------------------+
| New concrete | 0.55 |
+------------------+---------------------+
| Ocean ice | 0.50 to 0.70 |
+------------------+---------------------+
| Fresh snow | 0.80 |
+------------------+---------------------+
| Aluminium | 0.85 |
+------------------+---------------------+
: Sample albedos
Any albedo in visible light falls within a range of about 0.9 for fresh snow to about 0.04 for charcoal, one of the darkest substances. Deeply shadowed cavities can achieve an effective albedo approaching the zero of a black body. When seen from a distance, the ocean surface has a low albedo, as do most forests, whereas desert areas have some of the highest albedos among landforms. Most land areas are in an albedo range of 0.1 to 0.4. The average albedo of Earth is about 0.3. This is far higher than for the ocean primarily because of the contribution of clouds.
Earth\'s surface albedo is regularly estimated via Earth observation satellite sensors such as NASA\'s MODIS instruments on board the Terra and Aqua satellites, and the CERES instrument on the Suomi NPP and JPSS. As the amount of reflected radiation is only measured for a single direction by satellite, not all directions, a mathematical model is used to translate a sample set of satellite reflectance measurements into estimates of directional-hemispherical reflectance and bi-hemispherical reflectance (e.g.,). These calculations are based on the bidirectional reflectance distribution function (BRDF), which describes how the reflectance of a given surface depends on the view angle of the observer and the solar angle. BDRF can facilitate translations of observations of reflectance into albedo.
Earth\'s average surface temperature due to its albedo and the greenhouse effect is currently about 15 C. If Earth were frozen entirely (and hence be more reflective), the average temperature of the planet would drop below −40 C. If only the continental land masses became covered by glaciers, the mean temperature of the planet would drop to about 0 C. In contrast, if the entire Earth was covered by water -- a so-called ocean planet -- the average temperature on the planet would rise to almost 27 C.
In 2021, scientists reported that Earth dimmed by \~0.5% over two decades (1998--2017) as measured by earthshine using modern photometric techniques. This may have both been co-caused by climate change as well as a substantial increase in global warming. However, the link to climate change has not been explored to date and it is unclear whether or not this represents an ongoing trend.
### White-sky, black-sky, and blue-sky albedo {#white_sky_black_sky_and_blue_sky_albedo}
For land surfaces, it has been shown that the albedo at a particular solar zenith angle *θ*~*i*~ can be approximated by the proportionate sum of two terms:
- the directional-hemispherical reflectance at that solar zenith angle, ${\bar \alpha(\theta_i)}$, sometimes referred to as black-sky albedo, and
- the bi-hemispherical reflectance, $\bar{ \bar \alpha}$, sometimes referred to as white-sky albedo.
with ${1-D}$ being the proportion of direct radiation from a given solar angle, and ${D}$ being the proportion of diffuse illumination, the actual albedo ${\alpha}$ (also called blue-sky albedo) can then be given as:
$$\alpha = (1 - D) \bar\alpha(\theta_i) + D \bar{\bar\alpha}.$$
This formula is important because it allows the albedo to be calculated for any given illumination conditions from a knowledge of the intrinsic properties of the surface.
### Changes to albedo due to human activities {#changes_to_albedo_due_to_human_activities}
Human activities (e.g., deforestation, farming, and urbanization) change the albedo of various areas around the globe. Human impacts to \"the physical properties of the land surface can perturb the climate by altering the Earth's radiative energy balance\" even on a small scale or when undetected by satellites.
Urbanization generally decreases albedo (commonly being 0.01--0.02 lower than adjacent croplands), which contributes to global warming. Deliberately increasing albedo in urban areas can mitigate the urban heat island effect. An estimate in 2022 found that on a global scale, \"an albedo increase of 0.1 in worldwide urban areas would result in a cooling effect that is equivalent to absorbing \~44 Gt of CO~2~ emissions.\"
Intentionally enhancing the albedo of the Earth\'s surface, along with its daytime thermal emittance, has been proposed as a solar radiation management strategy to mitigate energy crises and global warming known as passive daytime radiative cooling (PDRC). Efforts toward widespread implementation of PDRCs may focus on maximizing the albedo of surfaces from very low to high values, so long as a thermal emittance of at least 90% can be achieved.
The tens of thousands of hectares of greenhouses in Almería, Spain form a large expanse of whitened plastic roofs. A 2008 study found that this anthropogenic change lowered the local surface area temperature of the high-albedo area, although changes were localized. A follow-up study found that \"CO2-eq. emissions associated to changes in surface albedo are a consequence of land transformation\" and can reduce surface temperature increases associated with climate change.
## Examples of terrestrial albedo effects {#examples_of_terrestrial_albedo_effects}
thumb\|upright=1.3\|The percentage of diffusely reflected sunlight relative to various surface conditions
### Illumination
Albedo is not directly dependent on the illumination because changing the amount of incoming light proportionally changes the amount of reflected light, except in circumstances where a change in illumination induces a change in the Earth\'s surface at that location (e.g. through melting of reflective ice). However, albedo and illumination both vary by latitude. Albedo is highest near the poles and lowest in the subtropics, with a local maximum in the tropics.
### Insolation effects {#insolation_effects}
The intensity of albedo temperature effects depends on the amount of albedo and the level of local insolation (solar irradiance); high albedo areas in the Arctic and Antarctic regions are cold due to low insolation, whereas areas such as the Sahara Desert, which also have a relatively high albedo, will be hotter due to high insolation. Tropical and sub-tropical rainforest areas have low albedo, and are much hotter than their temperate forest counterparts, which have lower insolation. Because insolation plays such a big role in the heating and cooling effects of albedo, high insolation areas like the tropics will tend to show a more pronounced fluctuation in local temperature when local albedo changes.
Arctic regions notably release more heat back into space than what they absorb, effectively cooling the Earth. This has been a concern since arctic ice and snow has been melting at higher rates due to higher temperatures, creating regions in the arctic that are notably darker (being water or ground which is darker color) and reflects less heat back into space. This feedback loop results in a reduced albedo effect.
### Climate and weather {#climate_and_weather}
thumb\|right\|upright=1.5\| Some effects of global warming can either enhance (positive feedbacks such as the ice-albedo feedback) or inhibit (negative feedbacks) warming. Albedo affects climate by determining how much radiation a planet absorbs. The uneven heating of Earth from albedo variations between land, ice, or ocean surfaces can drive weather.
The response of the climate system to an initial forcing is modified by feedbacks: increased by \"self-reinforcing\" or \"positive\" feedbacks and reduced by \"balancing\" or \"negative\" feedbacks. The main reinforcing feedbacks are the water-vapour feedback, the ice--albedo feedback, and the net effect of clouds.
### Albedo--temperature feedback {#albedotemperature_feedback}
When an area\'s albedo changes due to snowfall, a snow--temperature feedback results. A layer of snowfall increases local albedo, reflecting away sunlight, leading to local cooling. In principle, if no outside temperature change affects this area (e.g., a warm air mass), the raised albedo and lower temperature would maintain the current snow and invite further snowfall, deepening the snow--temperature feedback. However, because local weather is dynamic due to the change of seasons, eventually warm air masses and a more direct angle of sunlight (higher insolation) cause melting. When the melted area reveals surfaces with lower albedo, such as grass, soil, or ocean, the effect is reversed: the darkening surface lowers albedo, increasing local temperatures, which induces more melting and thus reducing the albedo further, resulting in still more heating.
### Snow
Snow albedo is highly variable, ranging from as high as 0.9 for freshly fallen snow, to about 0.4 for melting snow, and as low as 0.2 for dirty snow. Over Antarctica, snow albedo averages a little more than 0.8. If a marginally snow-covered area warms, snow tends to melt, lowering the albedo, and hence leading to more snowmelt because more radiation is being absorbed by the snowpack (referred to as the ice--albedo positive feedback).
In Switzerland, the citizens have been protecting their glaciers with large white tarpaulins to slow down the ice melt. These large white sheets are helping to reject the rays from the sun and defecting the heat. Although this method is very expensive, it has been shown to work, reducing snow and ice melt by 60%.
Just as fresh snow has a higher albedo than does dirty snow, the albedo of snow-covered sea ice is far higher than that of sea water. Sea water absorbs more solar radiation than would the same surface covered with reflective snow. When sea ice melts, either due to a rise in sea temperature or in response to increased solar radiation from above, the snow-covered surface is reduced, and more surface of sea water is exposed, so the rate of energy absorption increases. The extra absorbed energy heats the sea water, which in turn increases the rate at which sea ice melts. As with the preceding example of snowmelt, the process of melting of sea ice is thus another example of a positive feedback. Both positive feedback loops have long been recognized as important for global warming.
Cryoconite, powdery windblown dust containing soot, sometimes reduces albedo on glaciers and ice sheets.
The dynamical nature of albedo in response to positive feedback, together with the effects of small errors in the measurement of albedo, can lead to large errors in energy estimates. Because of this, in order to reduce the error of energy estimates, it is important to measure the albedo of snow-covered areas through remote sensing techniques rather than applying a single value for albedo over broad regions.
### Small-scale effects {#small_scale_effects}
Albedo works on a smaller scale, too. In sunlight, dark clothes absorb more heat and light-coloured clothes reflect it better, thus allowing some control over body temperature by exploiting the albedo effect of the colour of external clothing.
### Solar photovoltaic effects {#solar_photovoltaic_effects}
Albedo can affect the electrical energy output of solar photovoltaic devices. For example, the effects of a spectrally responsive albedo are illustrated by the differences between the spectrally weighted albedo of solar photovoltaic technology based on hydrogenated amorphous silicon (a-Si:H) and crystalline silicon (c-Si)-based compared to traditional spectral-integrated albedo predictions. Research showed impacts of over 10% for vertically (90°) mounted systems, but such effects were substantially lower for systems with lower surface tilts. Spectral albedo strongly affects the performance of bifacial solar cells where rear surface performance gains of over 20% have been observed for c-Si cells installed above healthy vegetation. An analysis on the bias due to the specular reflectivity of 22 commonly occurring surface materials (both human-made and natural) provided effective albedo values for simulating the performance of seven photovoltaic materials mounted on three common photovoltaic system topologies: industrial (solar farms), commercial flat rooftops and residential pitched-roof applications.
### Trees
Forests generally have a low albedo because the majority of the ultraviolet and visible spectrum is absorbed through photosynthesis. For this reason, the greater heat absorption by trees could offset some of the carbon benefits of afforestation (or offset the negative climate impacts of deforestation). In other words: The climate change mitigation effect of carbon sequestration by forests is partially counterbalanced in that reforestation can decrease the reflection of sunlight (albedo).
In the case of evergreen forests with seasonal snow cover, albedo reduction may be significant enough for deforestation to cause a net cooling effect. Trees also impact climate in extremely complicated ways through evapotranspiration. The water vapor causes cooling on the land surface, causes heating where it condenses, acts as strong greenhouse gas, and can increase albedo when it condenses into clouds. Scientists generally treat evapotranspiration as a net cooling impact, and the net climate impact of albedo and evapotranspiration changes from deforestation depends greatly on local climate.
Mid-to-high-latitude forests have a much lower albedo during snow seasons than flat ground, thus contributing to warming. Modeling that compares the effects of albedo differences between forests and grasslands suggests that expanding the land area of forests in temperate zones offers only a temporary mitigation benefit.
In seasonally snow-covered zones, winter albedos of treeless areas are 10% to 50% higher than nearby forested areas because snow does not cover the trees as readily. Deciduous trees have an albedo value of about 0.15 to 0.18 whereas coniferous trees have a value of about 0.09 to 0.15. Variation in summer albedo across both forest types is associated with maximum rates of photosynthesis because plants with high growth capacity display a greater fraction of their foliage for direct interception of incoming radiation in the upper canopy. The result is that wavelengths of light not used in photosynthesis are more likely to be reflected back to space rather than being absorbed by other surfaces lower in the canopy.
Studies by the Hadley Centre have investigated the relative (generally warming) effect of albedo change and (cooling) effect of carbon sequestration on planting forests. They found that new forests in tropical and midlatitude areas tended to cool; new forests in high latitudes (e.g., Siberia) were neutral or perhaps warming.
Research in 2023, drawing from 176 flux stations globally, revealed a climate trade-off: increased carbon uptake from afforestation results in reduced albedo. Initially, this reduction may lead to moderate global warming over a span of approximately 20 years, but it is expected to transition into significant cooling thereafter.
### Water
thumb\|upright=1.3\|Reflectivity of smooth water at 20 C (refractive index=1.333) Water reflects light very differently from typical terrestrial materials. The reflectivity of a water surface is calculated using the Fresnel equations.
At the scale of the wavelength of light even wavy water is always smooth so the light is reflected in a locally specular manner (not diffusely). The glint of light off water is a commonplace effect of this. At small angles of incident light, waviness results in reduced reflectivity because of the steepness of the reflectivity-vs.-incident-angle curve and a locally increased average incident angle.
Although the reflectivity of water is very low at low and medium angles of incident light, it becomes very high at high angles of incident light such as those that occur on the illuminated side of Earth near the terminator (early morning, late afternoon, and near the poles). However, as mentioned above, waviness causes an appreciable reduction. Because light specularly reflected from water does not usually reach the viewer, water is usually considered to have a very low albedo in spite of its high reflectivity at high angles of incident light.
Note that white caps on waves look white (and have high albedo) because the water is foamed up, so there are many superimposed bubble surfaces which reflect, adding up their reflectivities. Fresh \'black\' ice exhibits Fresnel reflection. Snow on top of this sea ice increases the albedo to 0.9.
### Clouds
Cloud albedo has substantial influence over atmospheric temperatures. Different types of clouds exhibit different reflectivity, theoretically ranging in albedo from a minimum of near 0 to a maximum approaching 0.8. \"On any given day, about half of Earth is covered by clouds, which reflect more sunlight than land and water. Clouds keep Earth cool by reflecting sunlight, but they can also serve as blankets to trap warmth.\"
Albedo and climate in some areas are affected by artificial clouds, such as those created by the contrails of heavy commercial airliner traffic. A study following the burning of the Kuwaiti oil fields during Iraqi occupation showed that temperatures under the burning oil fires were as much as 10 C-change colder than temperatures several miles away under clear skies.
### Aerosol effects {#aerosol_effects}
Aerosols (very fine particles/droplets in the atmosphere) have both direct and indirect effects on Earth\'s radiative balance. The direct (albedo) effect is generally to cool the planet; the indirect effect (the particles act as cloud condensation nuclei and thereby change cloud properties) is less certain.
### Black carbon {#black_carbon}
Another albedo-related effect on the climate is from black carbon particles. The size of this effect is difficult to quantify: the Intergovernmental Panel on Climate Change estimates that the global mean radiative forcing for black carbon aerosols from fossil fuels is +0.2 W m^−2^, with a range +0.1 to +0.4 W m^−2^. Black carbon is a bigger cause of the melting of the polar ice cap in the Arctic than carbon dioxide due to its effect on the albedo.`{{Failed verification|date=January 2020}}`{=mediawiki}
## Astronomical albedo {#astronomical_albedo}
thumb\|upright=1.2\|The moon Titan is darker than Saturn even though they receive the same amount of sunlight. This is due to a difference in albedo (0.22 versus 0.499 in geometric albedo).In astronomy, the term **albedo** can be defined in several different ways, depending upon the application and the wavelength of electromagnetic radiation involved.
### Optical or visual albedo {#optical_or_visual_albedo}
The albedos of planets, satellites and minor planets such as asteroids can be used to infer much about their properties. The study of albedos, their dependence on wavelength, lighting angle (\"phase angle\"), and variation in time composes a major part of the astronomical field of photometry. For small and far objects that cannot be resolved by telescopes, much of what we know comes from the study of their albedos. For example, the absolute albedo can indicate the surface ice content of outer Solar System objects, the variation of albedo with phase angle gives information about regolith properties, whereas unusually high radar albedo is indicative of high metal content in asteroids.
Enceladus, a moon of Saturn, has one of the highest known optical albedos of any body in the Solar System, with an albedo of 0.99. Another notable high-albedo body is Eris, with an albedo of 0.96. Many small objects in the outer Solar System and asteroid belt have low albedos down to about 0.05. A typical comet nucleus has an albedo of 0.04. Such a dark surface is thought to be indicative of a primitive and heavily space weathered surface containing some organic compounds.
The overall albedo of the Moon is measured to be around 0.14, but it is strongly directional and non-Lambertian, displaying also a strong opposition effect. Although such reflectance properties are different from those of any terrestrial terrains, they are typical of the regolith surfaces of airless Solar System bodies.
Two common optical albedos that are used in astronomy are the (V-band) geometric albedo (measuring brightness when illumination comes from directly behind the observer) and the Bond albedo (measuring total proportion of electromagnetic energy reflected). Their values can differ significantly, which is a common source of confusion.
Planet Geometric Bond
--------- ----------- ------------------------------------
Mercury 0.142 0.088 or 0.068
Venus 0.689 0.76 or 0.77
Earth 0.434 0.294
Mars 0.170 0.250
Jupiter 0.538 0.343±0.032 and also 0.503±0.012
Saturn 0.499 0.342
Uranus 0.488 0.300
Neptune 0.442 0.290
In detailed studies, the directional reflectance properties of astronomical bodies are often expressed in terms of the five Hapke parameters which semi-empirically describe the variation of albedo with phase angle, including a characterization of the opposition effect of regolith surfaces. One of these five parameters is yet another type of albedo called the single-scattering albedo. It is used to define scattering of electromagnetic waves on small particles. It depends on properties of the material (refractive index), the size of the particle, and the wavelength of the incoming radiation.
An important relationship between an object\'s astronomical (geometric) albedo, absolute magnitude and diameter is given by: $A =\left ( \frac{1329\times10^{-H/5}}{D} \right ) ^2,$ where $A$ is the astronomical albedo, $D$ is the diameter in kilometers, and $H$ is the absolute magnitude.
### Radar albedo {#radar_albedo}
In planetary radar astronomy, a microwave (or radar) pulse is transmitted toward a planetary target (e.g. Moon, asteroid, etc.) and the echo from the target is measured. In most instances, the transmitted pulse is circularly polarized and the received pulse is measured in the same sense of polarization as the transmitted pulse (SC) and the opposite sense (OC). The echo power is measured in terms of radar cross-section, ${\sigma}_{OC}$, ${\sigma}_{SC}$, or ${\sigma}_{T}$ (total power, SC + OC) and is equal to the cross-sectional area of a metallic sphere (perfect reflector) at the same distance as the target that would return the same echo power.
Those components of the received echo that return from first-surface reflections (as from a smooth or mirror-like surface) are dominated by the OC component as there is a reversal in polarization upon reflection. If the surface is rough at the wavelength scale or there is significant penetration into the regolith, there will be a significant SC component in the echo caused by multiple scattering.
For most objects in the solar system, the OC echo dominates and the most commonly reported radar albedo parameter is the (normalized) OC radar albedo (often shortened to radar albedo): $\hat{\sigma}_\text{OC} = \frac{{\sigma}_\text{OC}}{\pi r^2}$
where the denominator is the effective cross-sectional area of the target object with mean radius, $r$. A smooth metallic sphere would have $\hat{\sigma}_\text{OC} = 1$.
#### Radar albedos of Solar System objects {#radar_albedos_of_solar_system_objects}
Object $\hat{\sigma}_\text{OC}$
---------------------- --------------------------
Moon 0.06
Mercury 0.05
Venus 0.10
Mars 0.06
Avg. S-type asteroid 0.14
Avg. C-type asteroid 0.13
Avg. M-type asteroid 0.26
Comet P/2005 JQ5 0.02
The values reported for the Moon, Mercury, Mars, Venus, and Comet P/2005 JQ5 are derived from the total (OC+SC) radar albedo reported in those references.
#### Relationship to surface bulk density {#relationship_to_surface_bulk_density}
In the event that most of the echo is from first surface reflections ($\hat{\sigma}_\text{OC} < 0.1$ or so), the OC radar albedo is a first-order approximation of the Fresnel reflection coefficient (aka reflectivity) and can be used to estimate the bulk density of a planetary surface to a depth of a meter or so (a few wavelengths of the radar wavelength which is typically at the decimeter scale) using the following empirical relationships:
$$\rho = \begin{cases}
3.20 \text{ g cm}^{-3} \ln \left( \frac{1 + \sqrt{0.83 \hat{\sigma}_\text{OC}}}{1 - \sqrt{0.83 \hat{\sigma}_\text{OC}}} \right) & \text{for } \hat{\sigma}_\text{OC} \le 0.07 \\
(6.944 \hat{\sigma}_\text{OC} + 1.083) \text{ g cm}^{-3} & \text{for } \hat{\sigma}_\text{OC} > 0.07
\end{cases}$$.
## History
The term albedo was introduced into optics by Johann Heinrich Lambert in his 1760 work *Photometria*.
| 2025-08-01T00:00:00 |
290 |
A
|
A-sharp}} `{{pp-semi|small=yes}}`{=mediawiki} `{{CS1 config|mode=}}`{=mediawiki} `{{Use dmy dates|date=November 2019}}`{=mediawiki} `{{Infobox grapheme
| letter = A a
| script = [[Latin script]]
| type = [[Alphabet]]
| typedesc = ic
| language = [[Latin language]]
| phonemes = {{flex list|width=2em|[{{IPAlink|a}}]|[{{IPAlink|ɑ}}]|[{{IPAlink|ɒ}}]|[{{IPAlink|æ}}]|[{{IPAlink|ə}}]|[{{IPAlink|ɛ}}]|[{{IPAlink|oː}}]|[{{IPAlink|ɔ}}]|[{{IPAlink|e}}]|[{{IPAlink|ʕ}}]|[{{IPAlink|ʌ}}] [{{IPAlink|ɐ}}] |{{IPAc-en|eɪ}}}}
| unicode = U+0041, U+0061
| alphanumber = 1
| fam1 = <hiero>F1</hiero>
| fam2 = [[File:Proto-semiticA-01.svg|class=skin-invert-image|20px|Proto-Sinaitic 'alp]]
| fam3 = [[File:Protoalef.svg|class=skin-invert-image|20px|Proto-Caananite aleph]]
| fam4 = [[File:Phoenician_aleph.svg|class=skin-invert-image|20px|Phoenician aleph]]
| fam5 = [[Alpha|Α α]]
| fam6 = [[𐌀]][[File:Greek-uncial-1.jpg|class=skin-invert-image|20px|Greek classical uncial]]
| fam7 = [[File:Semitic-2.jpg|class=skin-invert-image|20px|Early Latin A]][[File:Latin-uncial-1.jpg|class=skin-invert-image|20px|Latin 300 AD uncial, version 1]]
| usageperiod = {{circa|700 BCE}}{{snd}}present
| children = {{flex list|
* [[Æ]]
* [[Ä]]
* [[Â]]
* [[Ɑ]]
* [[Ʌ]]
* [[Ɐ]]
* [[ª]]
* [[Å]]
* [[₳]]
* [[@]]
* [[Ⓐ]]
* [[ⓐ]]
* [[⒜]]
* {{not a typo|[[🅰]]}}}}
| sisters = {{flex list|width=3em|
* [[𐌰]]
* [[А]]
* [[Ә]]
* [[Ӑ]]
* [[Aleph|<span>א</span> <span>ا</span> <span>ܐ</span>]]
* [[ࠀ]]
* [[𐎀]]
* [[ℵ]]
* [[አ]]
* [[ء]]
* [[Ա|Ա ա]]
* [[અ]]
* [[अ]]
* [[অ]]}}
| associates = [[List of Latin-script digraphs#A|a(x)]], [[Ae (digraph)|ae]], [[Eau (trigraph)|eau]], [[Au (digraph)|au]]
| direction = Left-to-right
| image = Latin_letter_A.svg
| imageclass = skin-invert-image
}}`{=mediawiki} `{{Latin letter info|a}}`{=mediawiki}
**A**, or **a**, is the first letter and the first vowel letter of the Latin alphabet, used in the modern English alphabet, and others worldwide. Its name in English is *a* (pronounced `{{IPAc-en|'|eɪ|audio=LL-Q1860 (eng)-Flame, not lame-A.wav}}`{=mediawiki} `{{respell|AY}}`{=mediawiki}), plural *aes*.`{{refn|group=nb|''Aes'' is the plural of the name of the letter. The plural of the letter itself is rendered ''A''s, A's, ''a''s, or a's.}}`{=mediawiki}
It is similar in shape to the Ancient Greek letter alpha, from which it derives. The uppercase version consists of the two slanting sides of a triangle, crossed in the middle by a horizontal bar. The lowercase version is often written in one of two forms: the double-storey \|a\| and single-storey \|ɑ\|. The latter is commonly used in handwriting and fonts based on it, especially fonts intended to be read by children, and is also found in italic type.
In English, *a* is the indefinite article, with the alternative form *an*.
## Name
In English, the name of the letter is the *long A* sound, pronounced `{{IPAc-en|'|eɪ}}`{=mediawiki}. Its name in most other languages matches the letter\'s pronunciation in open syllables. `{{wide image|Pronunciation of the name of the letter ⟨a⟩ in European languages.png|460px|Pronunciation of the name of the letter {{angbr|a}} in European languages. {{IPA|/a/}} and {{IPA|/aː/}} can differ phonetically between {{IPAblink|a}}, {{IPAblink|ä}}, {{IPAblink|æ}} and {{IPAblink|ɑ}} depending on the language.}}`{=mediawiki}
## History
The earliest known ancestor of A is *aleph*---the first letter of the Phoenician alphabet---where it represented a glottal stop `{{IPA|[ʔ]}}`{=mediawiki}, as Phoenician only used consonantal letters. In turn, the ancestor of aleph may have been a pictogram of an ox head in proto-Sinaitic script influenced by Egyptian hieroglyphs, styled as a triangular head with two horns extended.
When the ancient Greeks adopted the alphabet, they had no use for a letter representing a glottal stop---so they adapted the sign to represent the vowel `{{IPAslink|a}}`{=mediawiki}, calling the letter by the similar name *alpha*. In the earliest Greek inscriptions dating to the 8th century BC following the Greek Dark Ages, the letter rests upon its side. However, in the later Greek alphabet it generally resembles the modern capital form---though many local varieties can be distinguished by the shortening of one leg, or by the angle at which the cross line is set.
The Etruscans brought the Greek alphabet to the Italian Peninsula, and left the form of alpha unchanged. When the Romans adopted the Etruscan alphabet to write Latin, the resulting form used in the Latin script would come to be used to write many other languages, including English.
Egyptian Proto-Sinaitic Proto-Canaanite Phoenician Western Greek Etruscan Latin
---------- ---------------- ----------------- ------------ --------------- ---------- -------
### Typographic variants {#typographic_variants}
class=skin-invert-image\|thumb\|upright=0.55\|Different glyphs of the lowercase letter `{{angbr|a}}`{=mediawiki} thumb\|upright=0.55\|Allographs include a double-storey `{{angbr|a}}`{=mediawiki} and single-storey `{{angbr|ɑ}}`{=mediawiki}. `{{stack end}}`{=mediawiki} During Roman times, there were many variant forms of the letter A. First was the monumental or lapidary style, which was used when inscribing on stone or other more permanent media. There was also a cursive style used for everyday or utilitarian writing, which was done on more perishable surfaces. Due to the perishable nature of these surfaces, there are not as many examples of this style as there are of the monumental, but there are still many surviving examples of different types of cursive, such as majuscule cursive, minuscule cursive, and semi-cursive minuscule. Variants also existed that were intermediate between the monumental and cursive styles. The known variants include the early semi-uncial (`{{cx|3rd century}}`{=mediawiki}), the uncial (`{{cx|4th–8th centuries}}`{=mediawiki}), and the late semi-uncial (`{{cx|6th–8th centuries}}`{=mediawiki}).
------------- ---------
Blackletter Uncial
Roman Italic
------------- ---------
At the end of the Roman Empire (5th century AD), several variants of the cursive minuscule developed through Western Europe. Among these were the semi-cursive minuscule of Italy, the Merovingian script in France, the Visigothic script in Spain, and the Insular or Anglo-Irish semi-uncial or Anglo-Saxon majuscule of Great Britain. By the ninth century, the Caroline script, which was very similar to the present-day form, was the principal form used in book-making, before the advent of the printing press. This form was derived through a combining of prior forms.
15th-century Italy saw the formation of the two main variants that are known today. These variants, the *Italic* and *Roman* forms, were derived from the Caroline Script version. The Italic form `{{angbr|ɑ}}`{=mediawiki}, also called *script a*, is often used in handwriting; it consists of a circle with a vertical stroke on its right. In the hands of medieval Irish and English writers, this form gradually developed from a 5th-century form resembling the Greek letter tau `{{angbr|τ}}`{=mediawiki}. The Roman form `{{angbr|a}}`{=mediawiki} is found in most printed material, and consists of a small loop with an arc over it. Both derive from the majuscule form `{{angbr|A}}`{=mediawiki}. In Greek handwriting, it was common to join the left leg and horizontal stroke into a single loop, as demonstrated by the uncial version shown. Many fonts then made the right leg vertical. In some of these, the serif that began the right leg stroke developed into an arc, resulting in the printed form, while in others it was dropped, resulting in the modern handwritten form. Graphic designers refer to the *Italic* and *Roman* forms as *single-decker a* and *double decker a* respectively.
Italic type is commonly used to mark emphasis or more generally to distinguish one part of a text from the rest set in Roman type. There are some other cases aside from italic type where *script a* `{{angbr|ɑ}}`{=mediawiki}, also called *Latin alpha*, is used in contrast with Latin `{{angbr|a}}`{=mediawiki}, such as in the International Phonetic Alphabet.
## Use in writing systems {#use_in_writing_systems}
Orthography Phonemes
------------- -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
(pinyin)
English , `{{IPAslink|ɑː}}`{=mediawiki}, `{{IPAslink|ɒ}}`{=mediawiki}, `{{IPAslink|ɔː}}`{=mediawiki}, `{{IPA link|ɛ|/ɛː/}}`{=mediawiki}, `{{IPA|/eɪ/}}`{=mediawiki}, `{{IPAslink|ə}}`{=mediawiki}
French , `{{IPAslink|ɑ}}`{=mediawiki}
German , `{{IPAslink|aː}}`{=mediawiki}
Portuguese , `{{IPAslink|ɐ}}`{=mediawiki}
Saanich
Spanish
Turkish
: Pronunciation of `{{angbr|a}}`{=mediawiki} by language
Phone Orthography
------- -------------------------------------------------------------------------------------------------------------------------------------------------------------
Chuvash, Croatian, French, German, Indonesian, Italian, Malay, Polish, Portuguese, Spanish, Stavangersk Norwegian, Swedish, Tagalog, Turkish, Utrecht Dutch
Dutch (doubled), German
Afrikaans, Bulgarian, Spanish
New Zealand English, Lithuanian, Limburgish (doubled), Luxembourgish
Catalan, Czech, French, Northern England English, Terengganu Malay, Polish
West Frisian (doubled)
Bashkir, Spanish, Dutch, Finnish, French, Kaingang, Limburgish, Norwegian, Russian, West Frisian
Afrikaans (doubled), Danish, German, Southern England English, Kurdish, Norwegian
Azerbaijani, Kazakh, Luxembourgish
Southern England English, Hungarian, Kedah Malay
Hungarian
Swedish
Maastrichtian Limburgish, Ulster Irish
Danish, English, Russian, Zeta--Raška Serbian
Australian English, Bulgarian, Central Catalan, Emilian, Galician, Lithuanian, Portuguese, Tagalog, Ukrainian
Mapudungun
New Zealand English, Perak Malay
Chemnitz German, Transylvanian Romanian
Chemnitz German
Southern England English
English, Eastern Catalan
Saanich
English
: Cross-linguistic variation of `{{angbr|a}}`{=mediawiki} pronunciation
### English
In modern English orthography, the letter `{{angbr|a}}`{=mediawiki} represents at least seven different vowel sounds, here represented using the vowels of Received Pronunciation, with effects of `{{angbr|r}}`{=mediawiki} ignored and mergers in General American mentioned where relevant:
- the near-open front unrounded vowel `{{IPA|/æ/}}`{=mediawiki} as in *pad*
- the open back unrounded vowel `{{IPA|/ɑː/}}`{=mediawiki} as in *father*---merged with `{{IPAslink|ɒ}}`{=mediawiki} as `{{IPAslink|ɑ}}`{=mediawiki} in General American---which is closer to its original Latin and Greek sound
- the open back rounded vowel `{{IPA|/ɒ/}}`{=mediawiki} (merged with `{{IPA|/ɑː/}}`{=mediawiki} as `{{IPAslink|ɑ}}`{=mediawiki} in General American) in *was* and *what*
- the open-mid back rounded vowel `{{IPA|/ɔː/}}`{=mediawiki} in *water*
- the diphthong `{{IPA|/eɪ/}}`{=mediawiki} as in *ace* and *major*, usually when `{{vr|a}}`{=mediawiki} is followed by one, or occasionally two, consonants and then another vowel letter---this results from Middle English lengthening followed by the Great Vowel Shift
- a schwa `{{IPA|/ə/}}`{=mediawiki} in many unstressed syllables, as in *about*, *comma*, *solar*
The double `{{angbr|aa}}`{=mediawiki} sequence does not occur in native English words, but is found in some words derived from foreign languages such as *Aaron* and *aardvark*. However, `{{vr|a}}`{=mediawiki} occurs in many common digraphs, all with their own sound or sounds, particularly `{{vr|ai}}`{=mediawiki}, `{{vr|au}}`{=mediawiki}, `{{vr|aw}}`{=mediawiki}, `{{vr|ay}}`{=mediawiki}, `{{vr|ea}}`{=mediawiki} and `{{vr|oa}}`{=mediawiki}.
is the third-most-commonly used letter in English after `{{angbr|e}}`{=mediawiki} and `{{angbr|t}}`{=mediawiki}, as well as in French; it is the second most common in Spanish, and the most common in Portuguese. `{{angbr|a}}`{=mediawiki} represents approximately 8.2% of letters as used in English texts; the figure is around 7.6% in French 11.5% in Spanish, and 14.6% in Portuguese.
### Other languages {#other_languages}
In most languages that use the Latin alphabet, `{{angbr|a}}`{=mediawiki} denotes an open unrounded vowel, such as `{{IPAslink|a}}`{=mediawiki}, `{{IPAslink|ä}}`{=mediawiki}, or `{{IPAslink|ɑ}}`{=mediawiki}. An exception is Saanich, in which `{{angbr|a}}`{=mediawiki}---and the glyph `{{angbr|[[Á]]}}`{=mediawiki}---stands for a close-mid front unrounded vowel `{{IPA|/e/}}`{=mediawiki}.
### Other systems {#other_systems}
- In the International Phonetic Alphabet, `{{angbr IPA|a}}`{=mediawiki} is used for the open front unrounded vowel, `{{angbr IPA|ä}}`{=mediawiki} is used for the open central unrounded vowel, and `{{angbr IPA|ɑ}}`{=mediawiki} is used for the open back unrounded vowel.
- In X-SAMPA, `{{angbr|a}}`{=mediawiki} is used for the open front unrounded vowel and `{{angbr|A}}`{=mediawiki} is used for the open back unrounded vowel.
## Other uses {#other_uses}
- When using base-16 notation, A or a is the conventional numeral corresponding to the number 10.
- In algebra, the letter *a* along with various other letters of the alphabet is often used to denote a variable, with various conventional meanings in different areas of mathematics. In 1637, René Descartes \"invented the convention of representing unknowns in equations by x, y, and z, and knowns by a, b, and c\", and this convention is still often followed, especially in elementary algebra.
- In geometry, capital Latin letters are used to denote objects including line segments, lines, and rays A capital A is also typically used as one of the letters to represent an angle in a triangle, the lowercase a representing the side opposite angle A.
- A is often used to denote something or someone of a better or more prestigious quality or status: A−, A or A+, the best grade that can be assigned by teachers for students\' schoolwork; \"A grade\" for clean restaurants; A-list celebrities, A1 at Lloyd\'s for shipping, etc. Such associations can have a motivating effect, as exposure to the letter A has been found to improve performance, when compared with other letters.
- A is used to denote size, as in a narrow size shoe, or a small cup size in a brassiere.
## Related characters {#related_characters}
### Latin alphabet {#latin_alphabet}
- `{{angbr|Æ æ}}`{=mediawiki}: a ligature of `{{angbr|AE}}`{=mediawiki} originally used in Latin
- with diacritics: Å å Ǻ ǻ Ḁ ḁ ẚ Ă ă Ặ ặ Ắ ắ Ằ ằ Ẳ ẳ Ẵ ẵ Ȃ ȃ Â â Ậ ậ Ấ ấ Ầ ầ Ẫ ẫ Ẩ ẩ Ả ả Ǎ ǎ Ⱥ ⱥ Ȧ ȧ Ǡ ǡ Ạ ạ Ä ä Ǟ ǟ À à Ȁ ȁ Á á Ā ā Ā̀ ā̀ Ã ã Ą ą Ą́ ą́ Ą̃ ą̃ A̲ a̲ ᶏ
- Phonetic alphabet symbols related to A---the International Phonetic Alphabet only uses lowercase, but uppercase forms are used in some other writing systems:
- : Latin alpha, represents an open back unrounded vowel in the IPA
- : Latin small alpha with a retroflex hook
- : Turned A, represents a near-open central vowel in the IPA
- : Turned V, represents an open-mid back unrounded vowel in IPA
- : Turned alpha or script A, represents an open back rounded vowel in the IPA
- : Modifier letter small turned alpha
- : Small capital A, an obsolete or non-standard symbol in the International Phonetic Alphabet used to represent various sounds (mainly open vowels)
- : Modifier letters are used in the Uralic Phonetic Alphabet (UPA), sometimes encoded with Unicode subscripts and superscripts
- : Subscript small a is used in Indo-European studies
- : Small letter a reversed-schwa is used in the Teuthonista phonetic transcription system
- : Glottal A, used in the transliteration of Ugaritic
### Derived signs, symbols and abbreviations {#derived_signs_symbols_and_abbreviations}
- : ordinal indicator
- : Ångström sign
- : turned capital letter A, used in predicate logic to specify universal quantification (\"for all\")
- : At sign
- : Argentine austral
- : anarchy symbol
### Ancestor and sibling letters {#ancestor_and_sibling_letters}
- : Phoenician aleph, from which the following symbols originally derive:
- : Greek letter alpha, from which the following letters derive:
- : Cyrillic letter A
- : Coptic letter alpha
- : Old Italic A, the ancestor of modern Latin A
- : Runic letter ansuz, which probably derives from old Italic A
- : Gothic letter aza
- : Armenian letter ayb
## Other representations {#other_representations}
### Computing
The Latin letters `{{angbr|A}}`{=mediawiki} and `{{angbr|a}}`{=mediawiki} have Unicode encodings `{{unichar|0041|Latin capital letter A}}`{=mediawiki} and `{{unichar|0061|Latin small letter a}}`{=mediawiki}. These are the same code points as those used in ASCII and ISO 8859. There are also precomposed character encodings for `{{angbr|A}}`{=mediawiki} and `{{angbr|a}}`{=mediawiki} with diacritics, for most of those listed above; the remainder are produced using combining diacritics.
Variant forms of the letter have unique code points for specialist use: the alphanumeric symbols set in mathematics and science, Latin alpha in linguistics, and halfwidth and fullwidth forms for legacy CJK font compatibility. The Cyrillic and Greek homoglyphs of the Latin `{{angbr|A}}`{=mediawiki} have separate encodings `{{unichar|0410|Cyrillic capital letter A|nlink=A (Cyrillic)}}`{=mediawiki} and `{{unichar|0391|Greek capital letter alpha|nlink=Alpha}}`{=mediawiki}.
### Other
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An American in Paris
|
***An American in Paris*** is a jazz-influenced symphonic poem (or tone poem) for orchestra by American composer George Gershwin first performed in 1928. It was inspired by the time that Gershwin had spent in Paris and evokes the sights and energy of the French capital during the **\[\[Années folles\]\]**.
Gershwin scored the piece for the standard instruments of the symphony orchestra plus celesta, saxophones, and automobile horns. He brought back four Parisian taxi horns for the New York premiere of the composition, which took place on December 13, 1928, in Carnegie Hall, with Walter Damrosch conducting the New York Philharmonic. It was Damrosch who had commissioned Gershwin to write his Concerto in F following the earlier success of *Rhapsody in Blue* (1924). He completed the orchestration on November 18, less than four weeks before the work\'s premiere. He collaborated on the original program notes with critic and composer Deems Taylor.
On January 1, 2025, *An American in Paris* entered the public domain.
## Background
Although the story is likely apocryphal, Gershwin is said to have been attracted by Maurice Ravel\'s unusual chords, and Gershwin went on his first trip to Paris in 1926 ready to study with Ravel. After his initial student audition with Ravel turned into a sharing of musical theories, Ravel said he could not teach him, saying, \"Why be a second-rate Ravel when you can be a first-rate Gershwin?\"
Gershwin strongly encouraged Ravel to come to the United States for a tour. To this end, upon his return to New York, Gershwin joined the efforts of Ravel\'s friend Robert Schmitz, a pianist Ravel had met during the war, to urge Ravel to tour the U.S. Schmitz was the head of Pro Musica, promoting Franco-American musical relations, and was able to offer Ravel a \$10,000 fee for the tour, an enticement Gershwin knew would be important to Ravel.
Gershwin greeted Ravel in New York in March 1928 during a party held for Ravel\'s birthday by Éva Gauthier. Ravel\'s tour reignited Gershwin\'s desire to return to Paris, which he and his brother Ira did after meeting Ravel. Ravel\'s high praise of Gershwin in an introductory letter to Nadia Boulanger caused Gershwin to seriously consider taking much more time to study abroad in Paris. Yet after he played for her, she told him she could not teach him. Boulanger gave Gershwin basically the same advice she gave all her accomplished master students: \"What could I give you that you haven\'t already got?\" This did not set Gershwin back, as his real intent abroad was to complete a new work based on Paris and perhaps a second rhapsody for piano and orchestra to follow his *Rhapsody in Blue*. Paris at this time hosted many expatriate writers, among them Ezra Pound, W. B. Yeats, Ernest Hemingway, F. Scott Fitzgerald and artist Pablo Picasso.
## Composition
{{-}} Gershwin based *An American in Paris* on a melodic fragment called \"Very Parisienne\", written in 1926 on his first visit to Paris as a gift to his hosts, Robert and Mabel Schirmer. Gershwin called it \"a rhapsodic ballet\"; it is written freely and in a much more modern idiom than his prior works.
Gershwin explained in *Musical America*, \"My purpose here is to portray the impressions of an American visitor in Paris as he strolls about the city, listens to the various street noises, and absorbs the French atmosphere.\"
The piece is structured into five sections, which culminate in a loose A--B--A format. Gershwin\'s first A episode introduces the two main \"walking\" themes in the \"Allegretto grazioso\" and develops a third theme in the \"Subito con brio\". The style of this A section is written in the typical French style of composers Claude Debussy and Les Six. This A section featured duple meter, singsong rhythms, and diatonic melodies with the sounds of oboe, English horn, and taxi horns. It also includes a melody fragment of the song \"La Sorella\" by Charles Borel-Clerc (1879--1959) (published in 1905).
The B section\'s \"Andante ma con ritmo deciso\" introduces the American Blues and spasms of homesickness.
The \"Allegro\" that follows continues to express homesickness in a faster twelve-bar blues. In the B section, Gershwin uses common time, syncopated rhythms, and bluesy melodies with the sounds of trumpet, saxophone, and snare drum. \"Moderato con grazia\" is the last A section that returns to the themes set in A. After recapitulating the \"walking\" themes, Gershwin overlays the slow blues theme from section B in the final \"Grandioso\".
## Response
Gershwin did not particularly like Walter Damrosch\'s interpretation at the world premiere of *An American in Paris*. He stated that Damrosch\'s sluggish, dragging tempo caused him to walk out of the hall during a matinee performance of this work. The audience, according to Edward Cushing, responded with \"a demonstration of enthusiasm impressively genuine in contrast to the conventional applause which new music, good and bad, ordinarily arouses.\"
Critics believed that *An American in Paris* was better crafted than Gershwin\'s Concerto in F. *Evening Post* did not think it belonged in a program with classical composers César Franck, Richard Wagner, or Guillaume Lekeu on its premiere. Gershwin responded to the critics:
## Instrumentation
*An American in Paris* was originally scored for 3 flutes (3rd doubling on piccolo), 2 oboes, English horn, 2 clarinets in B-flat, bass clarinet in B-flat, 2 bassoons, 4 horns in F, 3 trumpets in B-flat, 3 trombones, tuba, timpani, snare drum, bass drum, triangle, wood block, ratchet, cymbals, low and high tom-toms, xylophone, glockenspiel, celesta, 4 taxi horns labeled as A, B, C, and D with circles around them (but tuned as follows: A=Ab, B=Bb, C=D, and D=low A), alto saxophone, tenor saxophone, baritone saxophone (all doubling soprano and alto saxophones), and strings. Although most modern audiences have heard the taxi horns using the incorrect notes of A, B, C, and D, it had been Gershwin\'s intention to use the notes A`{{Music|flat}}`{=mediawiki}~4~, B`{{Music|flat}}`{=mediawiki}~4~, D~5~, and A~3~. It is likely that in labeling the taxi horns as A, B, C, and D with circles, he was referring to the four horns, and not the notes that they played. The correct tuning of the horns in sequence = D horn = low Ab, A horn = Ab an octave higher, B horn = Bb just above the Ab, and C horn = high D above the Bb.
A major revision of the work by composer and arranger F. Campbell-Watson simplified the instrumentation by reducing the saxophones to only three instruments: alto, tenor and baritone; the soprano and alto saxophone doublings were eliminated to avoid changing instruments. This became the standard performing edition until 2000, when Gershwin specialist Jack Gibbons made his own restoration of the original orchestration of *An American in Paris*, working directly from Gershwin\'s original manuscript, including the restoration of Gershwin\'s soprano saxophone parts removed in Campbell-Watson\'s revision. Gibbons\' restored orchestration of *An American in Paris* was performed at London\'s Queen Elizabeth Hall on July 9, 2000, by the City of Oxford Orchestra conducted by Levon Parikian.
William Daly arranged the score for piano solo; this was published by New World Music in 1929.
## Preservation status {#preservation_status}
On September 22, 2013, it was announced that a musicological critical edition of the full orchestral score would be eventually released. The Gershwin family, working in conjunction with the Library of Congress and the University of Michigan, were working to make scores available to the public that represent Gershwin\'s true intent. It was unknown whether the critical score would include the four minutes of material Gershwin later deleted from the work (such as the restatement of the blues theme after the faster 12 bar blues section), or if the score would document changes in the orchestration during Gershwin\'s composition process.
The score to *An American in Paris* was scheduled to be issued first in a series of scores to be released. The entire project was expected to take 30 to 40 years to complete, but *An American in Paris* was planned to be an early volume in the series.
Two urtext editions of the work were published by the German publisher B-Note Music in 2015. The changes made by Campbell-Watson were withdrawn in both editions. In the extended urtext, 120 bars of music were re-integrated. Conductor Walter Damrosch had cut them shortly before the first performance.
On September 9, 2017, The Cincinnati Symphony Orchestra gave the world premiere of the long-awaited critical edition of the piece prepared by Mark Clague, director of the Gershwin initiative at the University of Michigan. This performance was of the original 1928 orchestration.
## Recordings
*An American in Paris* has been frequently recorded. The first recording was made for the Victor Talking Machine Company in 1929 with Nathaniel Shilkret conducting the Victor Symphony Orchestra, drawn from members of the Philadelphia Orchestra. Gershwin was on hand to \"supervise\" the recording; however, Shilkret was reported to be in charge and eventually asked the composer to leave the recording studio. Then, a little later, Shilkret discovered there was no one to play the brief celesta solo during the slow section, so he hastily asked Gershwin if he might play the solo; Gershwin said he could and so he briefly participated in the actual recording. This recording is believed to use the taxi horns in the way that Gershwin had intended using the notes A-flat, B-flat, a higher D, and a lower A.
The radio broadcast of the September 8, 1937, Hollywood Bowl George Gershwin Memorial Concert, in which *An American in Paris,* also conducted by Shilkret, was second on the program, was recorded and was released in 1998 in a two-CD set.
Arthur Fiedler and the Boston Pops Orchestra recorded the work for RCA Victor, including one of the first stereo recordings of the music.
In 1945, Arturo Toscanini conducting the NBC Symphony Orchestra recorded the piece for RCA Victor, one of the few commercial recordings Toscanini made of music by an American composer.
The Seattle Symphony also recorded a version in 1990 of Gershwin\'s original score, before numerous edits were made resulting in the score as we hear it today.
The blues section of *An American in Paris* has been recorded separately by a number of artists; Ralph Flanagan & His Orchestra released it as a single in 1951 which reached No. 15 on the *Billboard* chart. Harry James released a version of the blues section on his 1953 album *One Night Stand,* recorded live at the Aragon Ballroom in Chicago (Columbia GL 522 and CL 522).
## Use in film {#use_in_film}
In 1951, Metro-Goldwyn-Mayer released the musical film *An American in Paris*, featuring Gene Kelly and Leslie Caron and directed by Vincente Minnelli. Winning the 1951 Best Picture Oscar and numerous other awards, the film featured many tunes of Gershwin and concluded with an extensive, elaborate dance sequence built around the symphonic poem *An American in Paris* (arranged for the film by Johnny Green), which at the time was the most expensive musical number ever filmed, costing \$500,000 `{{USDCY|500000|1951}}`{=mediawiki}.
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Actrius
|
***Actresses*** (Catalan: ***Actrius***) is a 1997 Catalan language Spanish drama film produced and directed by Ventura Pons and based on the award-winning stage play *E.R.* by Josep Maria Benet i Jornet. The film has no male actors, with all roles played by females. The film was produced in 1996.
## Synopsis
In order to prepare herself to play a role commemorating the life of legendary actress Empar Ribera, young actress (Mercè Pons) interviews three established actresses who had been the Ribera\'s pupils: the international diva Glòria Marc (Núria Espert), the television star Assumpta Roca (Rosa Maria Sardà), and dubbing director Maria Caminal (Anna Lizaran).
## Cast
- Núria Espert as Glòria Marc
- Rosa Maria Sardà as Assumpta Roca
- Anna Lizaran as Maria Caminal
- Mercè Pons as Estudiant
## Recognition
### Screenings
*Actrius* screened in 2001 at the Grauman\'s Egyptian Theatre in an American Cinematheque retrospective of the works of its director. The film had first screened at the same location in 1998. It was also shown at the 1997 Stockholm International Film Festival.
### Reception
In *Movie - Film - Review*, Christopher Tookey wrote that though the actresses were \"competent in roles that may have some reference to their own careers\", the film \"is visually unimaginative, never escapes its stage origins, and is almost totally lacking in revelation or surprising incident\". Noting that there were \"occasional, refreshing moments of intergenerational bitchiness\", they did not \"justify comparisons to *All About Eve*\", and were \"insufficiently different to deserve critical parallels with *Rashomon*\". He also wrote that *The Guardian* called the film a \"slow, stuffy chamber-piece\", and that *The Evening Standard* stated the film\'s \"best moments exhibit the bitchy tantrums seething beneath the threesome\'s composed veneers\". MRQE wrote \"This cinematic adaptation of a theatrical work is true to the original, but does not stray far from a theatrical rendering of the story.\"
### Awards and nominations {#awards_and_nominations}
- 1997, won \'Best Catalan Film\' at Butaca Awards for Ventura Pons
- 1997, won \'Best Catalan Film Actress\' at Butaca Awards, shared by Núria Espert, Rosa Maria Sardà, Anna Lizaran, and Mercè Pons
- 1998, nominated for \'Best Screenplay\' at Goya Awards, shared by Josep Maria Benet i Jornet and Ventura Pons
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Animalia (book)
|
***Animalia*** is an illustrated children\'s book by Graeme Base. It was originally published in 1986, followed by a tenth anniversary edition in 1996, and a 25th anniversary edition in 2012. Over four million copies have been sold worldwide. A special numbered and signed anniversary edition was also published in 1996, with an embossed gold jacket.
## Synopsis
*Animalia* is an alliterative alphabet book and contains twenty-six illustrations, one for each letter of the alphabet. Each illustration features an animal from the animal kingdom (A is for alligator and armadillo, B is for butterfly, C is for cat, etc.) along with a tongue-twister utilizing the letter of the page for many of the words. The illustrations contain many other objects beginning with that letter that the reader can try to identify (e.g. the \"D\" entry features, besides a pair of dragons, the dinosaur *Diplodocus* and the pelycosaur *Dimetrodon*; however, there are not necessarily \"a thousand things, or maybe more\", contrary to what the author states; for instance, the \"A\" entry features an alarm clock, as does the \"C\" entry; also, a tennis racket appears in the \"T\" entry as well as in the \"R\" entry). As an additional challenge, the author has hidden a picture of himself as a child in every picture.
## Related products {#related_products}
Julia MacRae Books published an *Animalia* colouring book in 2008. H. N. Abrams also published a wall calendar colouring book version for children the same year.
H. N. Abrams published *The Animalia Wall Frieze*, a fold-out over 26 feet in length, in which the author created new riddles for each letter.
The Great American Puzzle Factory created a 300-piece jigsaw puzzle based on the book\'s cover.
## Adaptations
A television series was also created, based on the book, which airs in Canada. The Australian Children\'s Television Foundation released a teaching resource DVD-ROM in 2011 to accompany the TV series with teaching aids for classroom use.
In 2010, The Base Factory and AppBooks released Animalia as an application for iPad and iPhone/iPod Touch.
## Awards
*Animalia* won the Young Australian\'s Best Book Award in 1987 for Best Picture Story Book.
The Children\'s Book Council of Australia designated *Animalia* a 1987 Picture Book of the Year: Honour Book.
Kid\'s Own Australian Literature Awards named *Animalia* the 1988 Picture Book Winner.
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International Atomic Time
|
**International Atomic Time** (abbreviated **TAI**, from its French name ***temps atomique international***) is a high-precision atomic coordinate time standard based on the notional passage of proper time on Earth\'s geoid. TAI is a weighted average of the time kept by over 450 atomic clocks in over 80 national laboratories worldwide. It is a continuous scale of time, without leap seconds, and it is the principal realisation of Terrestrial Time (with a fixed offset of epoch). It is the basis for Coordinated Universal Time (UTC), which is used for civil timekeeping all over the Earth\'s surface and which has leap seconds.
UTC deviates from TAI by a number of whole seconds. `{{as of|2017|01|01}}`{=mediawiki}, immediately after the most recent leap second was put into effect, UTC has been exactly 37 seconds behind TAI. The 37 seconds result from the initial difference of 10 seconds at the start of 1972, plus 27 leap seconds in UTC since 1972. In 2022, the General Conference on Weights and Measures decided to abandon the leap second by or before 2035, at which point the difference between TAI and UTC will remain fixed.
TAI may be reported using traditional means of specifying days, carried over from non-uniform time standards based on the rotation of the Earth. Specifically, both Julian days and the Gregorian calendar are used. TAI in this form was synchronised with Universal Time at the beginning of 1958, and the two have drifted apart ever since, due primarily to the slowing rotation of the Earth.
## Operation
TAI is a weighted average of the time kept by over 450 atomic clocks in over 80 national laboratories worldwide. The majority of the clocks involved are caesium clocks; the International System of Units (SI) definition of the second is based on caesium. The clocks are compared using GPS signals and two-way satellite time and frequency transfer. Due to the signal averaging TAI is an order of magnitude more stable than its best constituent clock.
The participating institutions each broadcast, in real time, a frequency signal with timecodes, which is their estimate of TAI. Time codes are usually published in the form of UTC, which differs from TAI by a well-known integer number of seconds. These time scales are denoted in the form *UTC(NPL)* in the UTC form, where *NPL* here identifies the National Physical Laboratory, UK. The TAI form may be denoted *TAI(NPL)*. The latter is not to be confused with *TA(NPL)*, which denotes an independent atomic time scale, not synchronised to TAI or to anything else.
The clocks at different institutions are regularly compared against each other. The International Bureau of Weights and Measures (BIPM, France), combines these measurements to retrospectively calculate the weighted average that forms the most stable time scale possible. This combined time scale is published monthly in \"Circular T\", and is the canonical TAI. This time scale is expressed in the form of tables of differences UTC − UTC(*k*) (equal to TAI − TAI(*k*)) for each participating institution *k*. The same circular also gives tables of TAI − TA(*k*), for the various unsynchronised atomic time scales.
Errors in publication may be corrected by issuing a revision of the faulty Circular T or by errata in a subsequent Circular T. Aside from this, once published in Circular T, the TAI scale is not revised. In hindsight, it is possible to discover errors in TAI and to make better estimates of the true proper time scale. Since the published circulars are definitive, better estimates do not create another version of TAI; it is instead considered to be creating a better realisation of Terrestrial Time (TT).
## History
Early atomic time scales consisted of quartz clocks with frequencies calibrated by a single atomic clock; the atomic clocks were not operated continuously. Atomic timekeeping services started experimentally in 1955, using the first caesium atomic clock at the National Physical Laboratory, UK (NPL). It was used as a basis for calibrating the quartz clocks at the Royal Greenwich Observatory and to establish a time scale, called Greenwich Atomic (GA). The United States Naval Observatory began the A.1 scale on 13 September 1956, using an Atomichron commercial atomic clock, followed by the NBS-A scale at the National Bureau of Standards, Boulder, Colorado on 9 October 1957.
The International Time Bureau (BIH) began a time scale, T~m~ or AM, in July 1955, using both local caesium clocks and comparisons to distant clocks using the phase of VLF radio signals. The BIH scale, A.1, and NBS-A were defined by an epoch at the beginning of 1958 The procedures used by the BIH evolved, and the name for the time scale changed: *A3* in 1964 and *TA(BIH)* in 1969.
The SI second was defined in terms of the caesium atom in 1967. From 1971 to 1975 the General Conference on Weights and Measures and the International Committee for Weights and Measures made a series of decisions that designated the BIPM time scale International Atomic Time (TAI).
In the 1970s, it became clear that the clocks participating in TAI were ticking at different rates due to gravitational time dilation, and the combined TAI scale, therefore, corresponded to an average of the altitudes of the various clocks. Starting from the Julian Date 2443144.5 (1 January 1977 00:00:00 TAI), corrections were applied to the output of all participating clocks, so that TAI would correspond to proper time at the geoid (mean sea level). Because the clocks were, on average, well above sea level, this meant that TAI slowed by about one part in a trillion. The former uncorrected time scale continues to be published under the name *EAL* (*Échelle Atomique Libre*, meaning *Free Atomic Scale*).
The instant that the gravitational correction started to be applied serves as the epoch for Barycentric Coordinate Time (TCB), Geocentric Coordinate Time (TCG), and Terrestrial Time (TT), which represent three fundamental time scales in the Solar System. All three of these time scales were defined to read JD 2443144.5003725 (1 January 1977 00:00:32.184) exactly at that instant. TAI was henceforth a realisation of TT, with the equation TT(TAI) = TAI + 32.184 s.
The continued existence of TAI was questioned in a 2007 letter from the BIPM to the ITU-R which stated, \"In the case of a redefinition of UTC without leap seconds, the CCTF would consider discussing the possibility of suppressing TAI, as it would remain parallel to the continuous UTC.\"
## Relation to UTC {#relation_to_utc}
Contrary to TAI, UTC is a discontinuous time scale. It is occasionally adjusted by leap seconds. Between these adjustments, it is composed of segments that are mapped to atomic time by a constant offset. From its beginning in 1961 through December 1971, the adjustments were made regularly in fractional leap seconds so that UTC approximated UT2. Afterwards, these adjustments were made only in whole seconds to approximate UT1. This was a compromise arrangement in order to enable a publicly broadcast time scale. The less frequent whole-second adjustments meant that the time scale would be more stable and easier to synchronize internationally. The fact that it continues to approximate UT1 means that tasks such as navigation which require a source of Universal Time continue to be well served by the public broadcast of UTC.
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Alain Connes
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**Alain Connes** (`{{IPA|fr|alɛ̃ kɔn|lang}}`{=mediawiki}; born 1 April 1947) is a French mathematician, known for his contributions to the study of operator algebras and noncommutative geometry. He was a professor at the *italic=no*, *italic=no*, Ohio State University and Vanderbilt University. He was awarded the Fields Medal in 1982.
## Career
Alain Connes attended high school at `{{Interlanguage link|Lycée Saint-Charles (Marseille)|lt=Lycée Saint-Charles|fr|Lycée Saint-Charles (Marseille)}}`{=mediawiki} in Marseille, and was then a student of the classes préparatoires in `{{Interlanguage link|Lycée Thiers|lt=Lycée Thiers|fr}}`{=mediawiki}. Between 1966 and 1970 he studied at École normale supérieure in Paris, and in 1973 he obtained a PhD from Pierre and Marie Curie University, under the supervision of Jacques Dixmier.
From 1970 to 1974 he was research fellow at the French National Centre for Scientific Research and during 1975 he held a visiting position at Queen\'s University at Kingston in Canada.
In 1976 he returned to France and worked as professor at Pierre and Marie Curie University until 1980 and at CNRS between 1981 and 1984. Moreover, since 1979 he holds the Léon Motchane Chair at IHES. From 1984 until his retirement in 2017 he held the chair of Analysis and Geometry at Collège de France.
In parallel, he was awarded a distinguished professorship at Vanderbilt University between 2003 and 2012, and at Ohio State University between 2012 and 2021.
## Research
Connes\' main research interests revolved around operator algebras. Besides noncommutative geometry, he has applied his works in various areas of mathematics and number theory, differential geometry. Since the 1990s, he developed noncommutative geometry.
In his early work on von Neumann algebras in the 1970s, he succeeded in obtaining the almost complete classification of injective factors. He also formulated the Connes embedding problem.
Following this, he made contributions in operator K-theory and index theory, which culminated in the Baum--Connes conjecture. He also introduced cyclic cohomology in the early 1980s as a first step in the study of noncommutative differential geometry.
He was a member of Nicolas Bourbaki. Over many years, he collaborated extensively with Henri Moscovici.
## Awards and honours {#awards_and_honours}
Connes was awarded the Peccot-Vimont Prize in 1976, the Ampère Prize in 1980, the Fields Medal in 1982, the Clay Research Award in 2000 and the Crafoord Prize in 2001. The French National Centre for Scientific Research granted him the silver medal in 1977 and the gold medal in 2004.
He was an invited speaker at the International Congress of Mathematicians in 1974 at Vancouver and in 1986 at Berkeley, and a plenary speaker at the ICM in 1978 at Helsinki. He was awarded honorary degrees from Queen\'s University at Kingston in 1979, University of Rome Tor Vergata in 1997, University of Oslo in 1999, University of Southern Denmark in 2009, Université libre de Bruxelles in 2010 and Shanghai Fudan University in 2017.
Since 1982 he is a member of the French Academy of Sciences. He was elected member of several foreign academies and societies, including the Royal Danish Academy of Sciences and Letters in 1980, the Norwegian Academy of Science and Letters in 1983, the American Academy of Arts and Sciences in 1989, the London Mathematical Society in 1994, the Canadian Academy of Sciences in 1995 (incorporated since 2002 in the Royal Society of Canada), the US National Academy of Sciences in 1997, the Russian Academy of Science in 2003 and the Royal Academy of Science, Letters and Fine Arts of Belgium in 2016.
In 2001 he received (together with his co-authors André Lichnerowicz and Marco Schutzenberger) the Peano Prize for his work *Triangle of Thoughts.*
## Family
Alain Connes is the middle-born of three sons -- born to parents both of whom lived to be 101 years old. He married in 1971.
## Books
- Alain Connes and Matilde Marcolli, *Noncommutative Geometry, Quantum Fields and Motives*, Colloquium Publications, American Mathematical Society, 2007, `{{ISBN|978-0-8218-4210-2}}`{=mediawiki} [1](http://www.alainconnes.org/docs/bookwebfinal.pdf)
- Alain Connes, André Lichnerowicz, and Marcel-Paul Schutzenberger, *Triangle of Thought*, translated by Jennifer Gage, American Mathematical Society, 2001, `{{ISBN|978-0-8218-2614-0}}`{=mediawiki}
- Jean-Pierre Changeux and Alain Connes, *Conversations on Mind, Matter, and Mathematics*, translated by M. B. DeBevoise, Princeton University Press, 1998, `{{ISBN|978-0-691-00405-1}}`{=mediawiki}
- Alain Connes, *Noncommutative Geometry*, Academic Press, 1994, `{{ISBN|978-0-12-185860-5}}`{=mediawiki}
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Analysis of variance
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**Analysis of variance (ANOVA)** is a family of statistical methods used to compare the means of two or more groups by analyzing variance. Specifically, ANOVA compares the amount of variation *between* the group means to the amount of variation *within* each group. If the between-group variation is substantially larger than the within-group variation, it suggests that the group means are likely different. This comparison is done using an F-test. The underlying principle of ANOVA is based on the law of total variance, which states that the total variance in a dataset can be broken down into components attributable to different sources. In the case of ANOVA, these sources are the variation between groups and the variation within groups.
ANOVA was developed by the statistician Ronald Fisher. In its simplest form, it provides a statistical test of whether two or more population means are equal, and therefore generalizes the *t*-test beyond two means. `{{TOC limit}}`{=mediawiki}
## History
While the analysis of variance reached fruition in the 20th century, antecedents extend centuries into the past according to Stigler. These include hypothesis testing, the partitioning of sums of squares, experimental techniques and the additive model. Laplace was performing hypothesis testing in the 1770s. Around 1800, Laplace and Gauss developed the least-squares method for combining observations, which improved upon methods then used in astronomy and geodesy. It also initiated much study of the contributions to sums of squares. Laplace knew how to estimate a variance from a residual (rather than a total) sum of squares. By 1827, Laplace was using least squares methods to address ANOVA problems regarding measurements of atmospheric tides. Before 1800, astronomers had isolated observational errors resulting from reaction times (the \"personal equation\") and had developed methods of reducing the errors. The experimental methods used in the study of the personal equation were later accepted by the emerging field of psychology which developed strong (full factorial) experimental methods to which randomization and blinding were soon added. An eloquent non-mathematical explanation of the additive effects model was available in 1885.
Ronald Fisher introduced the term variance and proposed its formal analysis in a 1918 article on theoretical population genetics, *The Correlation Between Relatives on the Supposition of Mendelian Inheritance*. His first application of the analysis of variance to data analysis was published in 1921, *Studies in Crop Variation I*. This divided the variation of a time series into components representing annual causes and slow deterioration. Fisher\'s next piece, *Studies in Crop Variation II*, written with Winifred Mackenzie and published in 1923, studied the variation in yield across plots sown with different varieties and subjected to different fertiliser treatments. Analysis of variance became widely known after being included in Fisher\'s 1925 book *Statistical Methods for Research Workers*.
Randomization models were developed by several researchers. The first was published in Polish by Jerzy Neyman in 1923.
## Example
The analysis of variance can be used to describe otherwise complex relations among variables. A dog show provides an example. A dog show is not a random sampling of the breed: it is typically limited to dogs that are adult, pure-bred, and exemplary. A histogram of dog weights from a show is likely to be rather complicated, like the yellow-orange distribution shown in the illustrations. Suppose we wanted to predict the weight of a dog based on a certain set of characteristics of each dog. One way to do that is to *explain* the distribution of weights by dividing the dog population into groups based on those characteristics. A successful grouping will split dogs such that (a) each group has a low variance of dog weights (meaning the group is relatively homogeneous) and (b) the mean of each group is distinct (if two groups have the same mean, then it isn\'t reasonable to conclude that the groups are, in fact, separate in any meaningful way). In the illustrations to the right, groups are identified as *X*~1~, *X*~2~, etc. In the first illustration, the dogs are divided according to the product (interaction) of two binary groupings: young vs old, and short-haired vs long-haired (e.g., group 1 is young, short-haired dogs, group 2 is young, long-haired dogs, etc.). Since the distributions of dog weight within each of the groups (shown in blue) has a relatively large variance, and since the means are very similar across groups, grouping dogs by these characteristics does not produce an effective way to explain the variation in dog weights: knowing which group a dog is in doesn\'t allow us to predict its weight much better than simply knowing the dog is in a dog show. Thus, this grouping fails to explain the variation in the overall distribution (yellow-orange).
An attempt to explain the weight distribution by grouping dogs as *pet vs working breed* and *less athletic vs more athletic* would probably be somewhat more successful (fair fit). The heaviest show dogs are likely to be big, strong, working breeds, while breeds kept as pets tend to be smaller and thus lighter. As shown by the second illustration, the distributions have variances that are considerably smaller than in the first case, and the means are more distinguishable. However, the significant overlap of distributions, for example, means that we cannot distinguish *X*~1~ and *X*~2~ reliably. Grouping dogs according to a coin flip might produce distributions that look similar.
An attempt to explain weight by breed is likely to produce a very good fit. All Chihuahuas are light and all St Bernards are heavy. The difference in weights between Setters and Pointers does not justify separate breeds. The analysis of variance provides the formal tools to justify these intuitive judgments. A common use of the method is the analysis of experimental data or the development of models. The method has some advantages over correlation: not all of the data must be numeric and one result of the method is a judgment in the confidence in an explanatory relationship.
## Classes of models {#classes_of_models}
There are three classes of models used in the analysis of variance, and these are outlined here.
### Fixed-effects models {#fixed_effects_models}
The fixed-effects model (class I) of analysis of variance applies to situations in which the experimenter applies one or more treatments to the subjects of the experiment to see whether the response variable values change. This allows the experimenter to estimate the ranges of response variable values that the treatment would generate in the population as a whole.
### Random-effects models {#random_effects_models}
Random-effects model (class II) is used when the treatments are not fixed. This occurs when the various factor levels are sampled from a larger population. Because the levels themselves are random variables, some assumptions and the method of contrasting the treatments (a multi-variable generalization of simple differences) differ from the fixed-effects model.
### Mixed-effects models {#mixed_effects_models}
A mixed-effects model (class III) contains experimental factors of both fixed and random-effects types, with appropriately different interpretations and analysis for the two types.
### Example {#example_1}
Teaching experiments could be performed by a college or university department to find a good introductory textbook, with each text considered a treatment. The fixed-effects model would compare a list of candidate texts. The random-effects model would determine whether important differences exist among a list of randomly selected texts. The mixed-effects model would compare the (fixed) incumbent texts to randomly selected alternatives.
Defining fixed and random effects has proven elusive, with multiple competing definitions.
## Assumptions
The analysis of variance has been studied from several approaches, the most common of which uses a linear model that relates the response to the treatments and blocks. Note that the model is linear in parameters but may be nonlinear across factor levels. Interpretation is easy when data is balanced across factors but much deeper understanding is needed for unbalanced data.
### Textbook analysis using a normal distribution {#textbook_analysis_using_a_normal_distribution}
The analysis of variance can be presented in terms of a linear model, which makes the following assumptions about the probability distribution of the responses:
- Independence of observations -- this is an assumption of the model that simplifies the statistical analysis.
- Normality -- the distributions of the residuals are normal.
- Equality (or \"homogeneity\") of variances, called homoscedasticity---the variance of data in groups should be the same.
The separate assumptions of the textbook model imply that the errors are independently, identically, and normally distributed for fixed effects models, that is, that the errors ($\varepsilon$) are independent and $\varepsilon \thicksim N(0, \sigma^2).$
### Randomization-based analysis {#randomization_based_analysis}
In a randomized controlled experiment, the treatments are randomly assigned to experimental units, following the experimental protocol. This randomization is objective and declared before the experiment is carried out. The objective random-assignment is used to test the significance of the null hypothesis, following the ideas of C. S. Peirce and Ronald Fisher. This design-based analysis was discussed and developed by Francis J. Anscombe at Rothamsted Experimental Station and by Oscar Kempthorne at Iowa State University. Kempthorne and his students make an assumption of *unit treatment additivity*, which is discussed in the books of Kempthorne and David R. Cox.
#### Unit-treatment additivity {#unit_treatment_additivity}
In its simplest form, the assumption of unit-treatment additivity states that the observed response $y_{i,j}$ from experimental unit $i$ when receiving treatment $j$ can be written as the sum of the unit\'s response $y_i$ and the treatment-effect $t_j$, that is $y_{i,j}=y_i+t_j.$ The assumption of unit-treatment additivity implies that, for every treatment $j$, the $j$th treatment has exactly the same effect $t_j$ on every experiment unit.
The assumption of unit treatment additivity usually cannot be directly falsified, according to Cox and Kempthorne. However, many *consequences* of treatment-unit additivity can be falsified. For a randomized experiment, the assumption of unit-treatment additivity *implies* that the variance is constant for all treatments. Therefore, by contraposition, a necessary condition for unit-treatment additivity is that the variance is constant.
The use of unit treatment additivity and randomization is similar to the design-based inference that is standard in finite-population survey sampling.
#### Derived linear model {#derived_linear_model}
Kempthorne uses the randomization-distribution and the assumption of *unit treatment additivity* to produce a *derived linear model*, very similar to the textbook model discussed previously. The test statistics of this derived linear model are closely approximated by the test statistics of an appropriate normal linear model, according to approximation theorems and simulation studies. However, there are differences. For example, the randomization-based analysis results in a small but (strictly) negative correlation between the observations. In the randomization-based analysis, there is *no assumption* of a *normal* distribution and certainly *no assumption* of *independence*. On the contrary, *the observations are dependent*!
The randomization-based analysis has the disadvantage that its exposition involves tedious algebra and extensive time. Since the randomization-based analysis is complicated and is closely approximated by the approach using a normal linear model, most teachers emphasize the normal linear model approach. Few statisticians object to model-based analysis of balanced randomized experiments.
#### Statistical models for observational data {#statistical_models_for_observational_data}
However, when applied to data from non-randomized experiments or observational studies, model-based analysis lacks the warrant of randomization. For observational data, the derivation of confidence intervals must use *subjective* models, as emphasized by Ronald Fisher and his followers. In practice, the estimates of treatment-effects from observational studies generally are often inconsistent. In practice, \"statistical models\" and observational data are useful for suggesting hypotheses that should be treated very cautiously by the public.
### Summary of assumptions {#summary_of_assumptions}
The normal-model based ANOVA analysis assumes the independence, normality, and homogeneity of variances of the residuals. The randomization-based analysis assumes only the homogeneity of the variances of the residuals (as a consequence of unit-treatment additivity) and uses the randomization procedure of the experiment. Both these analyses require homoscedasticity, as an assumption for the normal-model analysis and as a consequence of randomization and additivity for the randomization-based analysis.
However, studies of processes that change variances rather than means (called dispersion effects) have been successfully conducted using ANOVA. There are *no* necessary assumptions for ANOVA in its full generality, but the *F*-test used for ANOVA hypothesis testing has assumptions and practical limitations which are of continuing interest.
Problems which do not satisfy the assumptions of ANOVA can often be transformed to satisfy the assumptions. The property of unit-treatment additivity is not invariant under a \"change of scale\", so statisticians often use transformations to achieve unit-treatment additivity. If the response variable is expected to follow a parametric family of probability distributions, then the statistician may specify (in the protocol for the experiment or observational study) that the responses be transformed to stabilize the variance. Also, a statistician may specify that logarithmic transforms be applied to the responses which are believed to follow a multiplicative model. According to Cauchy\'s functional equation theorem, the logarithm is the only continuous transformation that transforms real multiplication to addition.
## Characteristics
ANOVA is used in the analysis of comparative experiments, those in which only the difference in outcomes is of interest. The statistical significance of the experiment is determined by a ratio of two variances. This ratio is independent of several possible alterations to the experimental observations: Adding a constant to all observations does not alter significance. Multiplying all observations by a constant does not alter significance. So ANOVA statistical significance result is independent of constant bias and scaling errors as well as the units used in expressing observations. In the era of mechanical calculation it was common to subtract a constant from all observations (when equivalent to dropping leading digits) to simplify data entry. This is an example of data coding.
## Algorithm
The calculations of ANOVA can be characterized as computing a number of means and variances, dividing two variances and comparing the ratio to a handbook value to determine statistical significance. Calculating a treatment effect is then trivial: \"the effect of any treatment is estimated by taking the difference between the mean of the observations which receive the treatment and the general mean\".
### Partitioning of the sum of squares {#partitioning_of_the_sum_of_squares}
`{{see also|Lack-of-fit sum of squares}}`{=mediawiki} ANOVA uses traditional standardized terminology. The definitional equation of sample variance is $s^2 = \frac{1}{n-1} \sum_i (y_i-\bar{y})^2$, where the divisor is called the degrees of freedom (DF), the summation is called the sum of squares (SS), the result is called the mean square (MS) and the squared terms are deviations from the sample mean. ANOVA estimates 3 sample variances: a total variance based on all the observation deviations from the grand mean, an error variance based on all the observation deviations from their appropriate treatment means, and a treatment variance. The treatment variance is based on the deviations of treatment means from the grand mean, the result being multiplied by the number of observations in each treatment to account for the difference between the variance of observations and the variance of means.
The fundamental technique is a partitioning of the total sum of squares *SS* into components related to the effects used in the model. For example, the model for a simplified ANOVA with one type of treatment at different levels.
$SS_\text{Total} = SS_\text{Error} + SS_\text{Treatments}$
The number of degrees of freedom *DF* can be partitioned in a similar way: one of these components (that for error) specifies a chi-squared distribution which describes the associated sum of squares, while the same is true for \"treatments\" if there is no treatment effect.
$DF_\text{Total} = DF_\text{Error} + DF_\text{Treatments}$
### The *F*-test {#the_f_test}
The *F*-test is used for comparing the factors of the total deviation. For example, in one-way, or single-factor ANOVA, statistical significance is tested for by comparing the F test statistic
$F = \frac{\text{variance between treatments}}{\text{variance within treatments}}$ $F = \frac{MS_\text{Treatments}}{MS_\text{Error}} = {{SS_\text{Treatments} / (I-1)} \over {SS_\text{Error} / (n_T-I)}}$
where *MS* is mean square, $I$ is the number of treatments and $n_T$ is the total number of cases to the *F*-distribution with $I - 1$ being the numerator degrees of freedom and $n_T - I$ the denominator degrees of freedom. Using the *F*-distribution is a natural candidate because the test statistic is the ratio of two scaled sums of squares each of which follows a scaled chi-squared distribution.
The expected value of F is $1 + {n \sigma^2_\text{Treatment}} / {\sigma^2_\text{Error}}$ (where $n$ is the treatment sample size) which is 1 for no treatment effect. As values of F increase above 1, the evidence is increasingly inconsistent with the null hypothesis. Two apparent experimental methods of increasing F are increasing the sample size and reducing the error variance by tight experimental controls.
There are two methods of concluding the ANOVA hypothesis test, both of which produce the same result:
- The textbook method is to compare the observed value of F with the critical value of F determined from tables. The critical value of F is a function of the degrees of freedom of the numerator and the denominator and the significance level (*α*). If F ≥ F~Critical~, the null hypothesis is rejected.
- The computer method calculates the probability (p-value) of a value of F greater than or equal to the observed value. The null hypothesis is rejected if this probability is less than or equal to the significance level (*α*).
The ANOVA *F*-test is known to be nearly optimal in the sense of minimizing false negative errors for a fixed rate of false positive errors (i.e. maximizing power for a fixed significance level). For example, to test the hypothesis that various medical treatments have exactly the same effect, the *F*-test\'s *p*-values closely approximate the permutation test\'s p-values: The approximation is particularly close when the design is balanced. Such permutation tests characterize tests with maximum power against all alternative hypotheses, as observed by Rosenbaum. The ANOVA *F*-test (of the null-hypothesis that all treatments have exactly the same effect) is recommended as a practical test, because of its robustness against many alternative distributions.
### Extended algorithm {#extended_algorithm}
ANOVA consists of separable parts; partitioning sources of variance and hypothesis testing can be used individually. ANOVA is used to support other statistical tools. Regression is first used to fit more complex models to data, then ANOVA is used to compare models with the objective of selecting simple(r) models that adequately describe the data. \"Such models could be fit without any reference to ANOVA, but ANOVA tools could then be used to make some sense of the fitted models, and to test hypotheses about batches of coefficients.\" \"\[W\]e think of the analysis of variance as a way of understanding and structuring multilevel models---not as an alternative to regression but as a tool for summarizing complex high-dimensional inferences \...\"
## For a single factor {#for_a_single_factor}
The simplest experiment suitable for ANOVA analysis is the completely randomized experiment with a single factor. More complex experiments with a single factor involve constraints on randomization and include completely randomized blocks and Latin squares (and variants: Graeco-Latin squares, etc.). The more complex experiments share many of the complexities of multiple factors.
There are some alternatives to conventional one-way analysis of variance, e.g.: Welch\'s heteroscedastic F test, Welch\'s heteroscedastic F test with trimmed means and Winsorized variances, Brown-Forsythe test, Alexander-Govern test, James second order test and Kruskal-Wallis test, available in [onewaytests](https://cran.r-project.org/web/packages/onewaytests/index.html) R
It is useful to represent each data point in the following form, called a statistical model: $Y_{ij} = \mu + \tau_j + \varepsilon_{ij}$ where
- *i* = 1, 2, 3, \..., *R*
- *j* = 1, 2, 3, \..., *C*
- *μ* = overall average (mean)
- *τ*~*j*~ = differential effect (response) associated with the *j* level of X; `{{pb}}`{=mediawiki} this assumes that overall the values of *τ*~*j*~ add to zero (that is, $\sum_{j = 1}^C \tau_j = 0$)
- *ε*~*ij*~ = noise or error associated with the particular *ij* data value
That is, we envision an additive model that says every data point can be represented by summing three quantities: the true mean, averaged over all factor levels being investigated, plus an incremental component associated with the particular column (factor level), plus a final component associated with everything else affecting that specific data value.
## For multiple factors {#for_multiple_factors}
ANOVA generalizes to the study of the effects of multiple factors. When the experiment includes observations at all combinations of levels of each factor, it is termed factorial. Factorial experiments are more efficient than a series of single factor experiments and the efficiency grows as the number of factors increases. Consequently, factorial designs are heavily used.
The use of ANOVA to study the effects of multiple factors has a complication. In a 3-way ANOVA with factors x, y and z, the ANOVA model includes terms for the main effects (x, y, z) and terms for interactions (xy, xz, yz, xyz). All terms require hypothesis tests. The proliferation of interaction terms increases the risk that some hypothesis test will produce a false positive by chance. Fortunately, experience says that high order interactions are rare. `{{verify source|date=December 2014}}`{=mediawiki} The ability to detect interactions is a major advantage of multiple factor ANOVA. Testing one factor at a time hides interactions, but produces apparently inconsistent experimental results.
Caution is advised when encountering interactions; Test interaction terms first and expand the analysis beyond ANOVA if interactions are found. Texts vary in their recommendations regarding the continuation of the ANOVA procedure after encountering an interaction. Interactions complicate the interpretation of experimental data. Neither the calculations of significance nor the estimated treatment effects can be taken at face value. \"A significant interaction will often mask the significance of main effects.\" Graphical methods are recommended to enhance understanding. Regression is often useful. A lengthy discussion of interactions is available in Cox (1958). Some interactions can be removed (by transformations) while others cannot.
A variety of techniques are used with multiple factor ANOVA to reduce expense. One technique used in factorial designs is to minimize replication (possibly no replication with support of analytical trickery) and to combine groups when effects are found to be statistically (or practically) insignificant. An experiment with many insignificant factors may collapse into one with a few factors supported by many replications.
## Associated analysis {#associated_analysis}
Some analysis is required in support of the *design* of the experiment while other analysis is performed after changes in the factors are formally found to produce statistically significant changes in the responses. Because experimentation is iterative, the results of one experiment alter plans for following experiments.
### Preparatory analysis {#preparatory_analysis}
#### The number of experimental units {#the_number_of_experimental_units}
In the design of an experiment, the number of experimental units is planned to satisfy the goals of the experiment. Experimentation is often sequential.
Early experiments are often designed to provide mean-unbiased estimates of treatment effects and of experimental error. Later experiments are often designed to test a hypothesis that a treatment effect has an important magnitude; in this case, the number of experimental units is chosen so that the experiment is within budget and has adequate power, among other goals.
Reporting sample size analysis is generally required in psychology. \"Provide information on sample size and the process that led to sample size decisions.\" The analysis, which is written in the experimental protocol before the experiment is conducted, is examined in grant applications and administrative review boards.
Besides the power analysis, there are less formal methods for selecting the number of experimental units. These include graphical methods based on limiting the probability of false negative errors, graphical methods based on an expected variation increase (above the residuals) and methods based on achieving a desired confidence interval.
#### Power analysis {#power_analysis}
Power analysis is often applied in the context of ANOVA in order to assess the probability of successfully rejecting the null hypothesis if we assume a certain ANOVA design, effect size in the population, sample size and significance level. Power analysis can assist in study design by determining what sample size would be required in order to have a reasonable chance of rejecting the null hypothesis when the alternative hypothesis is true.
#### Effect size {#effect_size}
Several standardized measures of effect have been proposed for ANOVA to summarize the strength of the association between a predictor(s) and the dependent variable or the overall standardized difference of the complete model. Standardized effect-size estimates facilitate comparison of findings across studies and disciplines. However, while standardized effect sizes are commonly used in much of the professional literature, a non-standardized measure of effect size that has immediately \"meaningful\" units may be preferable for reporting purposes.
#### Model confirmation {#model_confirmation}
Sometimes tests are conducted to determine whether the assumptions of ANOVA appear to be violated. Residuals are examined or analyzed to confirm homoscedasticity and gross normality. Residuals should have the appearance of (zero mean normal distribution) noise when plotted as a function of anything including time and modeled data values. Trends hint at interactions among factors or among observations.
#### Follow-up tests {#follow_up_tests}
A statistically significant effect in ANOVA is often followed by additional tests. This can be done in order to assess which groups are different from which other groups or to test various other focused hypotheses. Follow-up tests are often distinguished in terms of whether they are \"planned\" (a priori) or \"post hoc.\" Planned tests are determined before looking at the data, and post hoc tests are conceived only after looking at the data (though the term \"post hoc\" is inconsistently used).
The follow-up tests may be \"simple\" pairwise comparisons of individual group means or may be \"compound\" comparisons (e.g., comparing the mean pooling across groups A, B and C to the mean of group D). Comparisons can also look at tests of trend, such as linear and quadratic relationships, when the independent variable involves ordered levels. Often the follow-up tests incorporate a method of adjusting for the multiple comparisons problem.
Follow-up tests to identify which specific groups, variables, or factors have statistically different means include the Tukey\'s range test, and Duncan\'s new multiple range test. In turn, these tests are often followed with a Compact Letter Display (CLD) methodology in order to render the output of the mentioned tests more transparent to a non-statistician audience.
## Study designs {#study_designs}
There are several types of ANOVA. Many statisticians base ANOVA on the design of the experiment, especially on the protocol that specifies the random assignment of treatments to subjects; the protocol\'s description of the assignment mechanism should include a specification of the structure of the treatments and of any blocking. It is also common to apply ANOVA to observational data using an appropriate statistical model.
Some popular designs use the following types of ANOVA:
- One-way ANOVA is used to test for differences among two or more independent groups (means), e.g. different levels of urea application in a crop, or different levels of antibiotic action on several different bacterial species, or different levels of effect of some medicine on groups of patients. However, should these groups not be independent, and there is an order in the groups (such as mild, moderate and severe disease), or in the dose of a drug (such as 5 mg/mL, 10 mg/mL, 20 mg/mL) given to the same group of patients, then a linear trend estimation should be used. Typically, however, the one-way ANOVA is used to test for differences among at least three groups, since the two-group case can be covered by a t-test. When there are only two means to compare, the t-test and the ANOVA *F*-test are equivalent; the relation between ANOVA and *t* is given by `{{math|1=''F'' = ''t''<sup>2</sup>}}`{=mediawiki}.
- Factorial ANOVA is used when there is more than one factor.
- Repeated measures ANOVA is used when the same subjects are used for each factor (e.g., in a longitudinal study).
- Multivariate analysis of variance (MANOVA) is used when there is more than one response variable.
## Cautions
Balanced experiments (those with an equal sample size for each treatment) are relatively easy to interpret; unbalanced experiments offer more complexity. For single-factor (one-way) ANOVA, the adjustment for unbalanced data is easy, but the unbalanced analysis lacks both robustness and power. For more complex designs the lack of balance leads to further complications. \"The orthogonality property of main effects and interactions present in balanced data does not carry over to the unbalanced case. This means that the usual analysis of variance techniques do not apply. Consequently, the analysis of unbalanced factorials is much more difficult than that for balanced designs.\" In the general case, \"The analysis of variance can also be applied to unbalanced data, but then the sums of squares, mean squares, and *F*-ratios will depend on the order in which the sources of variation are considered.\"
ANOVA is (in part) a test of statistical significance. The American Psychological Association (and many other organisations) holds the view that simply reporting statistical significance is insufficient and that reporting confidence bounds is preferred.
## Generalizations
ANOVA is considered to be a special case of linear regression which in turn is a special case of the general linear model. All consider the observations to be the sum of a model (fit) and a residual (error) to be minimized.
The Kruskal-Wallis test and the Friedman test are nonparametric tests which do not rely on an assumption of normality.
### Connection to linear regression {#connection_to_linear_regression}
Below we make clear the connection between multi-way ANOVA and linear regression.
Linearly re-order the data so that $k$-th observation is associated with a response $y_k$ and factors $Z_{k,b}$ where $b \in \{1,2,\ldots,B\}$ denotes the different factors and $B$ is the total number of factors. In one-way ANOVA $B=1$ and in two-way ANOVA $B = 2$. Furthermore, we assume the $b$-th factor has $I_b$ levels, namely $\{1,2,\ldots,I_b\}$. Now, we can one-hot encode the factors into the $\sum_{b=1}^B I_b$ dimensional vector $v_k$.
The one-hot encoding function $g_b : \{1,2,\ldots,I_b\} \mapsto \{0,1\}^{I_b}$ is defined such that the $i$-th entry of $g_b(Z_{k,b})$ is $g_b(Z_{k,b})_i = \begin{cases}
1 & \text{if } i=Z_{k,b} \\
0 & \text{otherwise}
\end{cases}$ The vector $v_k$ is the concatenation of all of the above vectors for all $b$. Thus, $v_k = [g_1(Z_{k,1}), g_2(Z_{k,2}), \ldots, g_B(Z_{k,B})]$. In order to obtain a fully general $B$-way interaction ANOVA we must also concatenate every additional interaction term in the vector $v_k$ and then add an intercept term. Let that vector be $X_k$.
With this notation in place, we now have the exact connection with linear regression. We simply regress response $y_k$ against the vector $X_k$. However, there is a concern about identifiability. In order to overcome such issues we assume that the sum of the parameters within each set of interactions is equal to zero. From here, one can use *F*-statistics or other methods to determine the relevance of the individual factors.
#### Example {#example_2}
We can consider the 2-way interaction example where we assume that the first factor has 2 levels and the second factor has 3 levels.
Define $a_i = 1$ if $Z_{k,1}=i$ and $b_i = 1$ if $Z_{k,2} = i$, i.e. $a$ is the one-hot encoding of the first factor and $b$ is the one-hot encoding of the second factor.
With that, $X_k = [a_1, a_2, b_1, b_2, b_3 ,a_1 \times b_1, a_1 \times b_2, a_1 \times b_3, a_2 \times b_1, a_2 \times b_2, a_2 \times b_3, 1]$ where the last term is an intercept term. For a more concrete example suppose that $\begin{align}
Z_{k,1} & = 2 \\
Z_{k,2} & = 1
\end{align}$ Then, $X_k = [0,1,1,0,0,0,0,0,1,0,0,1]$
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640 |
Appellate procedure in the United States
|
**United States appellate procedure** involves the rules and regulations for filing appeals in state courts and federal courts. The nature of an appeal can vary greatly depending on the type of case and the rules of the court in the jurisdiction where the case was prosecuted. There are many types of standard of review for appeals, such as *de novo* and abuse of discretion. However, most appeals begin when a party files a petition for review to a higher court for the purpose of overturning the lower court\'s decision.
An appellate court is a court that hears cases on appeal from another court. Depending on the particular legal rules that apply to each circumstance, a party to a court case who is unhappy with the result might be able to challenge that result in an appellate court on specific grounds. These grounds typically could include errors of law, fact, procedure or due process. In different jurisdictions, appellate courts are also called appeals courts, courts of appeals, superior courts, or supreme courts.
The specific procedures for appealing, including even whether there is a right of appeal from a particular type of decision, can vary greatly from state to state. The right to file an appeal can also vary from state to state; for example, the New Jersey Constitution vests judicial power in a Supreme Court, a Superior Court, and other courts of limited jurisdiction, with an appellate court being part of the Superior Court.
## Access to appellant status {#access_to_appellant_status}
A party who files an appeal is called an \"appellant\", \"plaintiff in error\", \"petitioner\" or \"pursuer\", and a party on the other side is called an \"appellee\", \"defendant in error\", \"respondent\". A \"cross-appeal\" is an appeal brought by the respondent. For example, suppose at trial the judge found for the plaintiff and ordered the defendant to pay \$50,000. If the defendant files an appeal arguing that he should not have to pay any money, then the plaintiff might file a cross-appeal arguing that the defendant should have to pay \$200,000 instead of \$50,000.
The appellant is the party who, having lost part or all their claim in a lower court decision, is appealing to a higher court to have their case reconsidered. This is usually done on the basis that the lower court judge erred in the application of law, but it may also be possible to appeal on the basis of court misconduct, or that a finding of fact was entirely unreasonable to make on the evidence.
The appellant in the new case can be either the plaintiff (or claimant), defendant, third-party intervenor, or respondent (appellee) from the lower case, depending on who was the losing party. The winning party from the lower court, however, is now the respondent. In unusual cases the appellant can be the victor in the court below, but still appeal.
An appellee is the party to an appeal in which the lower court judgment was in its favor. The appellee is required to respond to the petition, oral arguments, and legal briefs of the appellant. In general, the appellee takes the procedural posture that the lower court\'s decision should be affirmed.
## Ability to appeal {#ability_to_appeal}
An appeal \"as of right\" is one that is guaranteed by statute or some underlying constitutional or legal principle. The appellate court cannot refuse to listen to the appeal. An appeal \"by leave\" or \"permission\" requires the appellant to obtain leave to appeal; in such a situation either or both of the lower court and the court may have the discretion to grant or refuse the appellant\'s demand to appeal the lower court\'s decision. In the Supreme Court, review in most cases is available only if the Court exercises its discretion and grants a writ of certiorari.
In tort, equity, or other civil matters either party to a previous case may file an appeal. In criminal matters, however, the state or prosecution generally has no appeal \"as of right\". And due to the double jeopardy principle, the state or prosecution may never appeal a jury or bench verdict of acquittal. But in some jurisdictions, the state or prosecution may appeal \"as of right\" from a trial court\'s dismissal of an indictment in whole or in part or from a trial court\'s granting of a defendant\'s suppression motion. Likewise, in some jurisdictions, the state or prosecution may appeal an issue of law \"by leave\" from the trial court or the appellate court. The ability of the prosecution to appeal a decision in favor of a defendant varies significantly internationally. All parties must present grounds to appeal, or it will not be heard.
By convention in some law reports, the appellant is named first. This can mean that where it is the defendant who appeals, the name of the case in the law reports reverses (in some cases twice) as the appeals work their way up the court hierarchy. This is not always true, however. In the federal courts, the parties\' names always stay in the same order as the lower court when an appeal is taken to the circuit courts of appeals, and are re-ordered only if the appeal reaches the Supreme Court.
## Direct or collateral: Appealing criminal convictions {#direct_or_collateral_appealing_criminal_convictions}
Many jurisdictions recognize two types of appeals, particularly in the criminal context. The first is the traditional \"direct\" appeal in which the appellant files an appeal with the next higher court of review. The second is the collateral appeal or post-conviction petition, in which the petitioner-appellant files the appeal in a court of first instance---usually the court that tried the case.
The key distinguishing factor between direct and collateral appeals is that the former occurs in state courts, and the latter in federal courts.`{{dubious|Non-federal collateral review|date=May 2017}}`{=mediawiki}
Relief in post-conviction is rare and is most often found in capital or violent felony cases. The typical scenario involves an incarcerated defendant locating DNA evidence demonstrating the defendant\'s actual innocence.
### Appellate review {#appellate_review}
\"Appellate review\" is the general term for the process by which courts with appellate jurisdiction take jurisdiction of matters decided by lower courts. It is distinguished from judicial review, which refers to the court\'s overriding constitutional or statutory right to determine if a legislative act or administrative decision is defective for jurisdictional or other reasons (which may vary by jurisdiction).
In most jurisdictions the normal and preferred way of seeking appellate review is by filing an appeal of the final judgment. Generally, an appeal of the judgment will also allow appeal of all other orders or rulings made by the trial court in the course of the case. This is because such orders cannot be appealed \"as of right\". However, certain critical interlocutory court orders, such as the denial of a request for an interim injunction, or an order holding a person in contempt of court, can be appealed immediately although the case may otherwise not have been fully disposed of.
There are two distinct forms of appellate review, \"direct\" and \"collateral\". For example, a criminal defendant may be convicted in state court, and lose on \"direct appeal\" to higher state appellate courts, and if unsuccessful, mount a \"collateral\" action such as filing for a writ of habeas corpus in the federal courts. Generally speaking, \"\[d\]irect appeal statutes afford defendants the opportunity to challenge the merits of a judgment and allege errors of law or fact. \... \[Collateral review\], on the other hand, provide\[s\] an independent and civil inquiry into the validity of a conviction and sentence, and as such are generally limited to challenges to constitutional, jurisdictional, or other fundamental violations that occurred at trial.\" \"Graham v. Borgen\", 483 F 3d. 475 (7th Cir. 2007) (no. 04--4103) (slip op. at 7) (citation omitted).
In Anglo-American common law courts, appellate review of lower court decisions may also be obtained by filing a petition for review by prerogative writ in certain cases. There is no corresponding right to a writ in any pure or continental civil law legal systems, though some mixed systems such as Quebec recognize these prerogative writs.
#### Direct appeal {#direct_appeal}
After exhausting the first appeal as of right, defendants usually petition the highest state court to review the decision. This appeal is known as a direct appeal. The highest state court, generally known as the Supreme Court, exercises discretion over whether it will review the case. On direct appeal, a prisoner challenges the grounds of the conviction based on an error that occurred at trial or some other stage in the adjudicative process.
##### Preservation issues {#preservation_issues}
An appellant\'s claim(s) must usually be preserved at trial. This means that the defendant had to object to the error when it occurred in the trial. Because constitutional claims are of great magnitude, appellate courts might be more lenient to review the claim even if it was not preserved. For example, Connecticut applies the following standard to review unpreserved claims: 1.the record is adequate to review the alleged claim of error; 2. the claim is of constitutional magnitude alleging the violation of a fundamental right; 3. the alleged constitutional violation clearly exists and clearly deprived the defendant of a fair trial; 4. if subject to harmless error analysis, the state has failed to demonstrate harmlessness of the alleged constitutional violation beyond a reasonable doubt.
#### State post-conviction relief: collateral appeal {#state_post_conviction_relief_collateral_appeal}
All States have a post-conviction relief process. Similar to federal post-conviction relief, an appellant can petition the court to correct alleged fundamental errors that were not corrected on direct review. Typical claims might include ineffective assistance of counsel and actual innocence based on new evidence. These proceedings are normally separate from the direct appeal, however some states allow for collateral relief to be sought on direct appeal. After direct appeal, the conviction is considered final. An appeal from the post conviction court proceeds just as a direct appeal. That is, it goes to the intermediate appellate court, followed by the highest court. If the petition is granted the appellant could be released from incarceration, the sentence could be modified, or a new trial could be ordered.
#### Habeas corpus {#habeas_corpus}
## Notice of appeal {#notice_of_appeal}
A \"notice of appeal\" is a form or document that in many cases is required to begin an appeal. The form is completed by the appellant or by the appellant\'s legal representative. The nature of this form can vary greatly from country to country and from court to court within a country.
The specific rules of the legal system will dictate exactly how the appeal is officially begun. For example, the appellant might have to file the notice of appeal with the appellate court, or with the court from which the appeal is taken, or both.
Some courts have samples of a notice of appeal on the court\'s own web site. In New Jersey, for example, the Administrative Office of the Court has promulgated a form of notice of appeal for use by appellants, though using this exact form is not mandatory and the failure to use it is not a jurisdictional defect provided that all pertinent information is set forth in whatever form of notice of appeal is used.
The deadline for beginning an appeal can often be very short: traditionally, it is measured in days, not months. This can vary from country to country, as well as within a country, depending on the specific rules in force. In the U.S. federal court system, criminal defendants must file a notice of appeal within 10 days of the entry of either the judgment or the order being appealed, or the right to appeal is forfeited.
## Appellate procedure {#appellate_procedure}
Generally speaking the appellate court examines the record of evidence presented in the trial court and the law that the lower court applied and decides whether that decision was legally sound or not. The appellate court will typically be deferential to the lower court\'s findings of fact (such as whether a defendant committed a particular act), unless clearly erroneous, and so will focus on the court\'s application of the law to those facts (such as whether the act found by the court to have occurred fits a legal definition at issue).
If the appellate court finds no defect, it \"affirms\" the judgment. If the appellate court does find a legal defect in the decision \"below\" (i.e., in the lower court), it may \"modify\" the ruling to correct the defect, or it may nullify (\"reverse\" or \"vacate\") the whole decision or any part of it. It may, in addition, send the case back (\"remand\" or \"remit\") to the lower court for further proceedings to remedy the defect.
In some cases, an appellate court may review a lower court decision \"de novo\" (or completely), challenging even the lower court\'s findings of fact. This might be the proper standard of review, for example, if the lower court resolved the case by granting a pre-trial motion to dismiss or motion for summary judgment which is usually based only upon written submissions to the trial court and not on any trial testimony.
Another situation is where appeal is by way of \"re-hearing\". Certain jurisdictions permit certain appeals to cause the trial to be heard afresh in the appellate court.
Sometimes, the appellate court finds a defect in the procedure the parties used in filing the appeal and dismisses the appeal without considering its merits, which has the same effect as affirming the judgment below. (This would happen, for example, if the appellant waited too long, under the appellate court\'s rules, to file the appeal.)
Generally, there is no trial in an appellate court, only consideration of the record of the evidence presented to the trial court and all the pre-trial and trial court proceedings are reviewed---unless the appeal is by way of re-hearing, new evidence will usually only be considered on appeal in \"very\" rare instances, for example if that material evidence was unavailable to a party for some very significant reason such as prosecutorial misconduct.
In some systems, an appellate court will only consider the written decision of the lower court, together with any written evidence that was before that court and is relevant to the appeal. In other systems, the appellate court will normally consider the record of the lower court. In those cases the record will first be certified by the lower court.
The appellant has the opportunity to present arguments for the granting of the appeal and the appellee (or respondent) can present arguments against it. Arguments of the parties to the appeal are presented through their appellate lawyers, if represented, or \"pro se\" if the party has not engaged legal representation. Those arguments are presented in written briefs and sometimes in oral argument to the court at a hearing. At such hearings each party is allowed a brief presentation at which the appellate judges ask questions based on their review of the record below and the submitted briefs.
In an adversarial system, appellate courts do not have the power to review lower court decisions unless a party appeals it. Therefore, if a lower court has ruled in an improper manner, or against legal precedent, that judgment will stand if not appealed -- even if it might have been overturned on appeal.
The United States legal system generally recognizes two types of appeals: a trial \"de novo\" or an appeal on the record.
A trial de novo is usually available for review of informal proceedings conducted by some minor judicial tribunals in proceedings that do not provide all the procedural attributes of a formal judicial trial. If unchallenged, these decisions have the power to settle more minor legal disputes once and for all. If a party is dissatisfied with the finding of such a tribunal, one generally has the power to request a trial \"de novo\" by a court of record. In such a proceeding, all issues and evidence may be developed newly, as though never heard before, and one is not restricted to the evidence heard in the lower proceeding. Sometimes, however, the decision of the lower proceeding is itself admissible as evidence, thus helping to curb frivolous appeals.
In some cases, an application for \"trial de novo\" effectively erases the prior trial as if it had never taken place. The Supreme Court of Virginia has stated that \'\"This Court has repeatedly held that the effect of an appeal to circuit court is to \"annul the judgment of the inferior tribunal as completely as if there had been no previous trial.\"\' The only exception to this is that if a defendant appeals a conviction for a crime having multiple levels of offenses, where they are convicted on a lesser offense, the appeal is of the lesser offense; the conviction represents an acquittal of the more serious offenses. \"\[A\] trial on the same charges in the circuit court does not violate double jeopardy principles, . . . subject only to the limitation that conviction in \[the\] district court for an offense lesser included in the one charged constitutes an acquittal of the greater offense, permitting trial de novo in the circuit court only for the lesser-included offense.\"
In an appeal on the record from a decision in a judicial proceeding, both appellant and respondent are bound to base their arguments wholly on the proceedings and body of evidence as they were presented in the lower tribunal. Each seeks to prove to the higher court that the result they desired was the just result. Precedent and case law figure prominently in the arguments. In order for the appeal to succeed, the appellant must prove that the lower court committed reversible error, that is, an impermissible action by the court acted to cause a result that was unjust, and which would not have resulted had the court acted properly. Some examples of reversible error would be erroneously instructing the jury on the law applicable to the case, permitting seriously improper argument by an attorney, admitting or excluding evidence improperly, acting outside the court\'s jurisdiction, injecting bias into the proceeding or appearing to do so, juror misconduct, etc. The failure to formally object at the time, to what one views as improper action in the lower court, may result in the affirmance of the lower court\'s judgment on the grounds that one did not \"preserve the issue for appeal\" by objecting.
In cases where a judge rather than a jury decided issues of fact, an appellate court will apply an \"abuse of discretion\" standard of review. Under this standard, the appellate court gives deference to the lower court\'s view of the evidence, and reverses its decision only if it were a clear abuse of discretion. This is usually defined as a decision outside the bounds of reasonableness. On the other hand, the appellate court normally gives less deference to a lower court\'s decision on issues of law, and may reverse if it finds that the lower court applied the wrong legal standard.
In some cases, an appellant may successfully argue that the law under which the lower decision was rendered was unconstitutional or otherwise invalid, or may convince the higher court to order a new trial on the basis that evidence earlier sought was concealed or only recently discovered. In the case of new evidence, there must be a high probability that its presence or absence would have made a material difference in the trial. Another issue suitable for appeal in criminal cases is effective assistance of counsel. If a defendant has been convicted and can prove that his lawyer did not adequately handle his case and that there is a reasonable probability that the result of the trial would have been different had the lawyer given competent representation, he is entitled to a new trial.
A lawyer traditionally starts an oral argument to any appellate court with the words \"May it please the court.\"
After an appeal is heard, the \"mandate\" is a formal notice of a decision by a court of appeal; this notice is transmitted to the trial court and, when filed by the clerk of the trial court, constitutes the final judgment on the case, unless the appeal court has directed further proceedings in the trial court. The mandate is distinguished from the appeal court\'s opinion, which sets out the legal reasoning for its decision. In some jurisdictions the mandate is known as the \"remittitur\".
## Results
The result of an appeal can be:
:\*Affirmed: Where the reviewing court basically agrees with the result of the lower courts\' ruling(s).
:\*Reversed: Where the reviewing court basically disagrees with the result of the lower courts\' ruling(s), and overturns their decision.
:\*Vacated: Where the reviewing court overturns the lower courts\' ruling(s) as invalid, without necessarily disagreeing with it/them, e.g. because the case was decided on the basis of a legal principle that no longer applies.
:\*Remanded: Where the reviewing court sends the case back to the lower court.
There can be multiple outcomes, so that the reviewing court can affirm some rulings, reverse others and remand the case all at the same time. Remand is not required where there is nothing left to do in the case. \"Generally speaking, an appellate court\'s judgment provides \'the final directive of the appeals courts as to the matter appealed, setting out with specificity the court\'s determination that the action appealed from should be affirmed, reversed, remanded or modified\'\".
Some reviewing courts who have discretionary review may send a case back without comment other than *review improvidently granted*. In other words, after looking at the case, they chose not to say anything. The result for the case of *review improvidently granted* is effectively the same as affirmed, but without that extra higher court stamp of approval.
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Answer (law)
|
In law, an **answer** was originally a solemn assertion in opposition to someone or something, and thus generally any counter-statement or defense, a reply to a question or response, or objection, or a correct solution of a problem.
In the common law, an **answer** is the first pleading by a defendant, usually filed and served upon the plaintiff within a certain strict time limit after a civil complaint or criminal information or indictment has been served upon the defendant. It may have been preceded by an *optional* \"pre-answer\" motion to dismiss or demurrer; if such a motion is unsuccessful, the defendant *must* file an answer to the complaint or risk an adverse default judgment.
In a criminal case, there is usually an arraignment or some other kind of appearance before the defendant comes to court. The pleading in the criminal case, which is entered on the record in open court, is usually either guilty or not guilty. Generally, speaking in private, civil cases there is no plea entered of guilt or innocence. There is only a judgment that grants money damages or some other kind of equitable remedy such as restitution or a permanent injunction. Criminal cases may lead to fines or other punishment, such as imprisonment.
The famous Latin *Responsa Prudentium* (\"answers of the learned ones\") were the accumulated views of many successive generations of Roman lawyers, a body of legal opinion which gradually became authoritative.
During debates of a contentious nature, deflection, colloquially known as \'changing the topic\', has been widely observed, and is often seen as a failure to answer a question.
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American National Standards Institute
|
ASA film speed\|other uses\|ANSI (disambiguation)}} `{{Distinguish|ASCII}}`{=mediawiki} `{{Update|date=July 2020}}`{=mediawiki} `{{Use mdy dates|date=June 2013}}`{=mediawiki} `{{Infobox organization
| name = American National Standards Institute
| image = ANSI logo.svg
| alt = The official logo of the American National Standards Institute
| caption = <!-- If the year that the current logo was introduced is known, that may be provide a useful caption. Otherwise, please not simply "the logo of ANSI". -->
| msize = <!-- map size, optional, default 200px -->
| malt = <!-- map alt text -->
| mcaption = <!-- optional -->
| abbreviation = ANSI
| motto =
| formation = {{Start date and age|1918|10|19|paren=yes}}<ref>{{cite journal|date=October 19, 1918|title=Minutes|journal=American Engineering Standards Committee |page=1}}</ref>
| type = [[Nonprofit organization]]
| status = [[501(c)(3) organization|501(c)(3)]] private
| purpose = [[Standards organization|National standards]]
| headquarters = [[Washington, D.C.]], U.S.<br />{{Coordinates|38|54|14|N|77|02|35|W}}
| location =
| region_served =
| membership = 125,000 companies and 3.5 million professionals<ref name="membership" />
| language = [[American English|English]]
| leader_title = President and [[Chief executive officer|CEO]]
| leader_name = Laurie E. Locascio, PhD
| main_organ = <!--(gral. assembly, board of directors, etc)-->
| affiliations =
| num_staff =
| num_volunteers =
| budget =
| website = {{Official URL}}
| remarks =
}}`{=mediawiki}
The **American National Standards Institute** (**ANSI** `{{IPAc-en|ˈ|æ|n|s|i|audio=LL-Q1860 (eng)-Naomi Persephone Amethyst (NaomiAmethyst)-ANSI.wav}}`{=mediawiki} `{{respell|AN|see}}`{=mediawiki}) is a private nonprofit organization that oversees the development of voluntary consensus standards for products, services, processes, systems, and personnel in the United States.`{{ref RFC|4949}}`{=mediawiki} The organization also coordinates U.S. standards with international standards so that American products can be used worldwide.
ANSI accredits standards that are developed by representatives of other standards organizations, government agencies, consumer groups, companies, and others. These standards ensure that the characteristics and performance of products are consistent, that people use the same definitions and terms, and that products are tested the same way. ANSI also accredits organizations that carry out product or personnel certification in accordance with requirements defined in international standards.
The organization\'s headquarters are in Washington, D.C. ANSI\'s operations office is located in New York City. The ANSI annual operating budget is funded by the sale of publications, membership dues and fees, accreditation services, fee-based programs, and international standards programs.
Many ANSI regulations are incorporated by reference into United States federal statutes (i.e. by OSHA regulations referring to individual ANSI specifications). ANSI does not make these standards publicly available, and charges money for access to these documents; it further claims that it is copyright infringement for them to be provided to the public by others free of charge. These assertions have been the subject of criticism and litigation.
## History
ANSI was most likely formed in 1918, when five engineering societies and three government agencies founded the **American Engineering Standards Committee** (**AESC**). In 1928, the AESC became the **American Standards Association** (**ASA**).
In 1966, the ASA was reorganized and became the **United States of America Standards Institute** (**USASI**).
In February 1969, Ralph Nader harshly criticized the USASI in public remarks as \"manifestly deceptive\" in several different ways. He specifically attacked the name USASI as improperly implying some kind of official connection with the federal government of the United States.
The present name was adopted in 1969.
Prior to 1918, these five founding engineering societies:
- American Institute of Electrical Engineers (AIEE, now IEEE)
- American Society of Mechanical Engineers (ASME)
- American Society of Civil Engineers (ASCE)
- American Institute of Mining Engineers (AIME, now American Institute of Mining, Metallurgical, and Petroleum Engineers)
- American Society for Testing and Materials (now ASTM International)
had been members of the United Engineering Society (UES). At the behest of the AIEE, they invited the U.S. government Departments of War, Navy (combined in 1947 to become the Department of Defense or DOD) and Commerce to join in founding a national standards organization.
According to Adam Stanton, the first permanent secretary and head of staff in 1919, AESC started as an ambitious program and little else. Staff for the first year consisted of one executive, Clifford B. LePage, who was on loan from a founding member, ASME. An annual budget of \$7,500 was provided by the founding bodies.
In 1931, the organization (renamed ASA in 1928) became affiliated with the U.S. National Committee of the International Electrotechnical Commission (IEC), which had been formed in 1904 to develop electrical and electronics standards.
## Members
ANSI\'s members are government agencies, organizations, academic and international bodies, and individuals. In total, the Institute represents the interests of more than 270,000 companies and organizations and 30 million professionals worldwide.
ANSI\'s market-driven, decentralized approach has been criticized in comparison with more planned and organized international approaches to standardization. An underlying issue is the difficulty of balancing \"the interests of both the nation\'s industrial and commercial sectors and the nation as a whole.\"
## Process
Although ANSI itself does not develop standards, the Institute oversees the development and use of standards by accrediting the procedures of standards developing organizations. ANSI accreditation signifies that the procedures used by standards developing organizations meet the institute\'s requirements for openness, balance, consensus, and due process.
ANSI also designates specific standards as American National Standards, or ANS, when the Institute determines that the standards were developed in an environment that is equitable, accessible and responsive to the requirements of various stakeholders.
Voluntary consensus standards quicken the market acceptance of products while making clear how to improve the safety of those products for the protection of consumers. There are approximately 9,500 American National Standards that carry the ANSI designation.
The American National Standards process involves:
- consensus by a group that is open to representatives from all interested parties
- broad-based public review and comment on draft standards
- consideration of and response to comments
- incorporation of submitted changes that meet the same consensus requirements into a draft standard
- availability of an appeal by any participant alleging that these principles were not respected during the standards-development process.
## International activities {#international_activities}
In addition to facilitating the formation of standards in the United States, ANSI promotes the use of U.S. standards internationally, advocates U.S. policy and technical positions in international and regional standards organizations, and encourages the adoption of international standards as national standards where appropriate.
The institute is the official U.S. representative to the two major international standards organizations, the International Organization for Standardization (ISO), as a founding member, and the International Electrotechnical Commission (IEC), via the U.S. National Committee (USNC). ANSI participates in almost the entire technical program of both the ISO and the IEC, and administers many key committees and subgroups. In many instances, U.S. standards are taken forward to ISO and IEC, through ANSI or the USNC, where they are adopted in whole or in part as international standards.
Adoption of ISO and IEC standards as American standards increased from 0.2% in 1986 to 15.5% in May 2012.
### Standards panels {#standards_panels}
The Institute administers nine standards panels:
- ANSI Homeland Defense and Security Standardization Collaborative (HDSSC)
- ANSI Nanotechnology Standards Panel (ANSI-NSP)
- ID Theft Prevention and ID Management Standards Panel (IDSP)
- ANSI Energy Efficiency Standardization Coordination Collaborative (EESCC)
- Nuclear Energy Standards Coordination Collaborative (NESCC)
- Electric Vehicles Standards Panel (EVSP)
- ANSI-NAM Network on Chemical Regulation
- ANSI Biofuels Standards Coordination Panel
- Healthcare Information Technology Standards Panel (HITSP)
Each of the panels works to identify, coordinate, and harmonize voluntary standards relevant to these areas.
In 2009, ANSI and the National Institute of Standards and Technology (NIST) formed the Nuclear Energy Standards Coordination Collaborative (NESCC). NESCC is a joint initiative to identify and respond to the current need for standards in the nuclear industry.
### American national standards {#american_national_standards}
- The ASA (as for American Standards Association) photographic exposure system, originally defined in ASA Z38.2.1 (since 1943) and ASA PH2.5 (since 1954), together with the DIN system (DIN 4512 since 1934), became the basis for the ISO system (since 1974), currently used worldwide (ISO 6, ISO 2240, ISO 5800, ISO 12232).
- A standard for the set of values used to represent characters in digital computers. The ANSI code standard extended the previously created ASCII seven bit code standard (ASA X3.4-1963), with additional codes for European alphabets (see also Extended Binary Coded Decimal Interchange Code or EBCDIC). In Microsoft Windows, the phrase \"ANSI\" refers to the Windows ANSI code pages (even though they are not ANSI standards). Most of these are fixed width, though some characters for ideographic languages are variable width. Since these characters are based on a draft of the ISO-8859 series, some of Microsoft\'s symbols are visually very similar to the ISO symbols, leading many to falsely assume that they are identical.
- The first computer programming language standard was \"American Standard Fortran\" (informally known as \"FORTRAN 66\"), approved in March 1966 and published as ASA X3.9-1966.
- The programming language COBOL had ANSI standards in 1968, 1974, and 1985. The COBOL 2002 standard was issued by ISO.
- The original standard implementation of the C programming language was standardized as ANSI X3.159-1989, becoming the well-known ANSI C.
- The X3J13 committee was created in 1986 to formalize the ongoing consolidation of Common Lisp, culminating in 1994 with the publication of ANSI\'s first object-oriented programming standard.
- A popular Unified Thread Standard for nuts and bolts is ANSI/ASME B1.1 which was defined in 1935, 1949, 1989, and 2003.
- The ANSI-NSF International standards used for commercial kitchens, such as restaurants, cafeterias, delis, etc.
- The ANSI/APSP (Association of Pool & Spa Professionals) standards used for pools, spas, hot tubs, barriers, and suction entrapment avoidance.
- The ANSI/HI (Hydraulic Institute) standards used for pumps.
- The ANSI for eye protection is Z87.1, which gives a specific impact resistance rating to the eyewear. This standard is commonly used for shop glasses, shooting glasses, and many other examples of protective eyewear. While compliance to this standard is required by United States federal law, it is not made freely available by ANSI, who charges \$65 to read a PDF of it.
- The ANSI paper sizes (ANSI/ASME Y14.1).
| 2025-08-01T00:00:00 |
666 |
Alkali metal
|
+----------------------------------+
| ↓ Period |
+==================================+
| 2 |
+----------------------------------+
| 3 |
+----------------------------------+
| 4 |
+----------------------------------+
| 5 |
+----------------------------------+
| 6 |
+----------------------------------+
| 7 |
+----------------------------------+
| *Legend* |
| |
| ------------------------------ |
| primordial |
| element by radioactive decay |
| ------------------------------ |
+----------------------------------+
The **alkali metals** consist of the chemical elements lithium (Li), sodium (Na), potassium (K), rubidium (Rb), caesium (Cs),`{{refn|''Caesium'' is the spelling recommended by the [[International Union of Pure and Applied Chemistry]] (IUPAC).<ref>{{RedBook2005|pages=248–49}}.</ref> The [[American Chemical Society]] (ACS) has used the spelling ''cesium'' since 1921,<ref>{{cite book |editor1-first= Anne M. |editor1-last= Coghill |editor2-first= Lorrin R. |editor2-last= Garson |year= 2006 |title= The ACS Style Guide: Effective Communication of Scientific Information |edition= 3rd |publisher= American Chemical Society |location= Washington, D.C. |isbn= 978-0-8412-3999-9 |page= [https://archive.org/details/acsstyleguideeff0000unse/page/127 127] |url= https://archive.org/details/acsstyleguideeff0000unse/page/127 }}</ref><ref>{{cite journal |journal=Pure Appl. Chem. |volume=70 |issue=1 |last1=Coplen |pages= 237–257 |year= 1998 |first1=T. B. |url= http://old.iupac.org/reports/1998/7001coplen/history.pdf |archive-url=https://ghostarchive.org/archive/20221009/http://old.iupac.org/reports/1998/7001coplen/history.pdf |archive-date=2022-10-09 |url-status=live |last2=Peiser |first2=H. S. |title= History of the recommended atomic-weight values from 1882 to 1997: a comparison of differences from current values to the estimated uncertainties of earlier values |doi= 10.1351/pac199870010237|s2cid=96729044 }}</ref> following ''Webster's Third New International Dictionary''.|group=note}}`{=mediawiki} and francium (Fr). Together with hydrogen they constitute group 1,`{{refn|In both the old IUPAC and the [[Chemical Abstracts Service|CAS]] systems for group numbering, this group is known as '''group IA''' (pronounced as "group one A", as the "I" is a [[Roman numeral]]).<ref name = fluck>{{cite journal |last1=Fluck |first1=E. |year=1988 |title=New Notations in the Periodic Table |journal=[[Pure Appl. Chem.]] |volume=60 |issue=3 |pages=431–436 |publisher=[[IUPAC]] |doi=10.1351/pac198860030431 |s2cid=96704008 |url=http://www.iupac.org/publications/pac/1988/pdf/6003x0431.pdf |archive-url=https://ghostarchive.org/archive/20221009/http://www.iupac.org/publications/pac/1988/pdf/6003x0431.pdf |archive-date=2022-10-09 |url-status=live |access-date=24 March 2012}}</ref>|name=group-numbering|group=note}}`{=mediawiki} which lies in the s-block of the periodic table. All alkali metals have their outermost electron in an s-orbital: this shared electron configuration results in their having very similar characteristic properties.`{{refn|While hydrogen also has this electron configuration, it is not considered an alkali metal as it has very different behaviour owing to the lack of [[valence electron|valence]] p-orbitals in [[period 1 element]]s.|group=note}}`{=mediawiki} Indeed, the alkali metals provide the best example of group trends in properties in the periodic table, with elements exhibiting well-characterised homologous behaviour. This family of elements is also known as the **lithium family** after its leading element.
The alkali metals are all shiny, soft, highly reactive metals at standard temperature and pressure and readily lose their outermost electron to form cations with charge +1. They can all be cut easily with a knife due to their softness, exposing a shiny surface that tarnishes rapidly in air due to oxidation by atmospheric moisture and oxygen (and in the case of lithium, nitrogen). Because of their high reactivity, they must be stored under oil to prevent reaction with air, and are found naturally only in salts and never as the free elements. Caesium, the fifth alkali metal, is the most reactive of all the metals. All the alkali metals react with water, with the heavier alkali metals reacting more vigorously than the lighter ones.
All of the discovered alkali metals occur in nature as their compounds: in order of abundance, sodium is the most abundant, followed by potassium, lithium, rubidium, caesium, and finally francium, which is very rare due to its extremely high radioactivity; francium occurs only in minute traces in nature as an intermediate step in some obscure side branches of the natural decay chains. Experiments have been conducted to attempt the synthesis of element 119, which is likely to be the next member of the group; none were successful. However, ununennium may not be an alkali metal due to relativistic effects, which are predicted to have a large influence on the chemical properties of superheavy elements; even if it does turn out to be an alkali metal, it is predicted to have some differences in physical and chemical properties from its lighter homologues.
Most alkali metals have many different applications. One of the best-known applications of the pure elements is the use of rubidium and caesium in atomic clocks, of which caesium atomic clocks form the basis of the second. A common application of the compounds of sodium is the sodium-vapour lamp, which emits light very efficiently. Table salt, or sodium chloride, has been used since antiquity. Lithium finds use as a psychiatric medication and as an anode in lithium batteries. Sodium, potassium and possibly lithium are essential elements, having major biological roles as electrolytes, and although the other alkali metals are not essential, they also have various effects on the body, both beneficial and harmful. \_\_TOC\_\_ `{{clear left}}`{=mediawiki}
## History
Sodium compounds have been known since ancient times; salt (sodium chloride) has been an important commodity in human activities. While potash has been used since ancient times, it was not understood for most of its history to be a fundamentally different substance from sodium mineral salts. Georg Ernst Stahl obtained experimental evidence which led him to suggest the fundamental difference of sodium and potassium salts in 1702, and Henri-Louis Duhamel du Monceau was able to prove this difference in 1736. The exact chemical composition of potassium and sodium compounds, and the status as chemical element of potassium and sodium, was not known then, and thus Antoine Lavoisier did not include either alkali in his list of chemical elements in 1789.
Pure potassium was first isolated in 1807 in England by Humphry Davy, who derived it from caustic potash (KOH, potassium hydroxide) by the use of electrolysis of the molten salt with the newly invented voltaic pile. Previous attempts at electrolysis of the aqueous salt were unsuccessful due to potassium\'s extreme reactivity. Potassium was the first metal that was isolated by electrolysis. Later that same year, Davy reported extraction of sodium from the similar substance caustic soda (NaOH, lye) by a similar technique, demonstrating the elements, and thus the salts, to be different.
Petalite (`{{chem2|LiAlSi4O10|auto=yes}}`{=mediawiki}) was discovered in 1800 by the Brazilian chemist José Bonifácio de Andrada in a mine on the island of Utö, Sweden. However, it was not until 1817 that Johan August Arfwedson, then working in the laboratory of the chemist Jöns Jacob Berzelius, detected the presence of a new element while analysing petalite ore. This new element was noted by him to form compounds similar to those of sodium and potassium, though its carbonate and hydroxide were less soluble in water and more alkaline than the other alkali metals. Berzelius gave the unknown material the name *lithion*/*lithina*, from the Greek word *λιθoς* (transliterated as *lithos*, meaning \"stone\"), to reflect its discovery in a solid mineral, as opposed to potassium, which had been discovered in plant ashes, and sodium, which was known partly for its high abundance in animal blood. He named the metal inside the material *lithium*. Lithium, sodium, and potassium were part of the discovery of periodicity, as they are among a series of triads of elements in the same group that were noted by Johann Wolfgang Döbereiner in 1850 as having similar properties.
Rubidium and caesium were the first elements to be discovered using the spectroscope, invented in 1859 by Robert Bunsen and Gustav Kirchhoff. The next year, they discovered caesium in the mineral water from Bad Dürkheim, Germany. Their discovery of rubidium came the following year in Heidelberg, Germany, finding it in the mineral lepidolite. The names of rubidium and caesium come from the most prominent lines in their emission spectra: a bright red line for rubidium (from the Latin word *rubidus*, meaning dark red or bright red), and a sky-blue line for caesium (derived from the Latin word *caesius*, meaning sky-blue).
Around 1865 John Newlands produced a series of papers where he listed the elements in order of increasing atomic weight and similar physical and chemical properties that recurred at intervals of eight; he likened such periodicity to the octaves of music, where notes an octave apart have similar musical functions. His version put all the alkali metals then known (lithium to caesium), as well as copper, silver, and thallium (which show the +1 oxidation state characteristic of the alkali metals), together into a group. His table placed hydrogen with the halogens.
thumb\|upright=1.75\|Dmitri Mendeleev\'s periodic system proposed in 1871 showing hydrogen and the alkali metals as part of his group I, along with copper, silver, and gold After 1869, Dmitri Mendeleev proposed his periodic table placing lithium at the top of a group with sodium, potassium, rubidium, caesium, and thallium. Two years later, Mendeleev revised his table, placing hydrogen in group 1 above lithium, and also moving thallium to the boron group. In this 1871 version, copper, silver, and gold were placed twice, once as part of group IB, and once as part of a \"group VIII\" encompassing today\'s groups 8 to 11. After the introduction of the 18-column table, the group IB elements were moved to their current position in the d-block, while alkali metals were left in *group IA*. Later the group\'s name was changed to *group 1* in 1988. The trivial name \"alkali metals\" comes from the fact that the hydroxides of the group 1 elements are all strong alkalis when dissolved in water.
There were at least four erroneous and incomplete discoveries before Marguerite Perey of the Curie Institute in Paris, France discovered francium in 1939 by purifying a sample of actinium-227, which had been reported to have a decay energy of 220 keV. However, Perey noticed decay particles with an energy level below 80 keV. Perey thought this decay activity might have been caused by a previously unidentified decay product, one that was separated during purification, but emerged again out of the pure actinium-227. Various tests eliminated the possibility of the unknown element being thorium, radium, lead, bismuth, or thallium. The new product exhibited chemical properties of an alkali metal (such as coprecipitating with caesium salts), which led Perey to believe that it was element 87, caused by the alpha decay of actinium-227. Perey then attempted to determine the proportion of beta decay to alpha decay in actinium-227. Her first test put the alpha branching at 0.6%, a figure that she later revised to 1%.
: `{{overunderset|→|α (1.38%)|21.77 y}}`{=mediawiki} **`{{nuclide|francium|223}}`{=mediawiki}** `{{overunderset|→|β<sup>−</sup>|22 min}}`{=mediawiki} `{{nuclide|radium|223}}`{=mediawiki} `{{overunderset|→|α|11.4 d}}`{=mediawiki}`{{nuclide|radon|219}}`{=mediawiki}
The next element below francium (eka-francium) in the periodic table would be ununennium (Uue), element 119. The synthesis of ununennium was first attempted in 1985 by bombarding a target of einsteinium-254 with calcium-48 ions at the superHILAC accelerator at the Lawrence Berkeley National Laboratory in Berkeley, California. No atoms were identified, leading to a limiting yield of 300 nb.
: \+ `{{nuclide|calcium|48|link=y}}`{=mediawiki} → `{{nuclide|ununennium|302}}`{=mediawiki}\* → *no atoms*
It is highly unlikely that this reaction will be able to create any atoms of ununennium in the near future, given the extremely difficult task of making sufficient amounts of einsteinium-254, which is favoured for production of ultraheavy elements because of its large mass, relatively long half-life of 270 days, and availability in significant amounts of several micrograms, to make a large enough target to increase the sensitivity of the experiment to the required level; einsteinium has not been found in nature and has only been produced in laboratories, and in quantities smaller than those needed for effective synthesis of superheavy elements. However, given that ununennium is only the first period 8 element on the extended periodic table, it may well be discovered in the near future through other reactions, and indeed an attempt to synthesise it is currently ongoing in Japan. Currently, none of the period 8 elements has been discovered yet, and it is also possible, due to drip instabilities, that only the lower period 8 elements, up to around element 128, are physically possible. No attempts at synthesis have been made for any heavier alkali metals: due to their extremely high atomic number, they would require new, more powerful methods and technology to make.
## Occurrence
### In the Solar System {#in_the_solar_system}
thumb\|upright=2.5\|Estimated abundances of the chemical elements in the Solar System. Hydrogen and helium are most common, from the Big Bang. The next three elements (lithium, beryllium, and boron) are rare because they are poorly synthesised in the Big Bang and also in stars. The two general trends in the remaining stellar-produced elements are: (1) an alternation of abundance in elements as they have even or odd atomic numbers, and (2) a general decrease in abundance, as elements become heavier. Iron is especially common because it represents the minimum-energy nuclide that can be made by fusion of helium in supernovae. The Oddo--Harkins rule holds that elements with even atomic numbers are more common that those with odd atomic numbers, with the exception of hydrogen. This rule argues that elements with odd atomic numbers have one unpaired proton and are more likely to capture another, thus increasing their atomic number. In elements with even atomic numbers, protons are paired, with each member of the pair offsetting the spin of the other, enhancing stability. All the alkali metals have odd atomic numbers and they are not as common as the elements with even atomic numbers adjacent to them (the noble gases and the alkaline earth metals) in the Solar System. The heavier alkali metals are also less abundant than the lighter ones as the alkali metals from rubidium onward can only be synthesised in supernovae and not in stellar nucleosynthesis. Lithium is also much less abundant than sodium and potassium as it is poorly synthesised in both Big Bang nucleosynthesis and in stars: the Big Bang could only produce trace quantities of lithium, beryllium and boron due to the absence of a stable nucleus with 5 or 8 nucleons, and stellar nucleosynthesis could only pass this bottleneck by the triple-alpha process, fusing three helium nuclei to form carbon, and skipping over those three elements.
### On Earth {#on_earth}
The Earth formed from the same cloud of matter that formed the Sun, but the planets acquired different compositions during the formation and evolution of the Solar System. In turn, the natural history of the Earth caused parts of this planet to have differing concentrations of the elements. The mass of the Earth is approximately 5.98`{{e|24}}`{=mediawiki} kg. It is composed mostly of iron (32.1%), oxygen (30.1%), silicon (15.1%), magnesium (13.9%), sulfur (2.9%), nickel (1.8%), calcium (1.5%), and aluminium (1.4%); with the remaining 1.2% consisting of trace amounts of other elements. Due to planetary differentiation, the core region is believed to be primarily composed of iron (88.8%), with smaller amounts of nickel (5.8%), sulfur (4.5%), and less than 1% trace elements.
The alkali metals, due to their high reactivity, do not occur naturally in pure form in nature. They are lithophiles and therefore remain close to the Earth\'s surface because they combine readily with oxygen and so associate strongly with silica, forming relatively low-density minerals that do not sink down into the Earth\'s core. Potassium, rubidium and caesium are also incompatible elements due to their large ionic radii.
Sodium and potassium are very abundant on Earth, both being among the ten most common elements in Earth\'s crust; sodium makes up approximately 2.6% of the Earth\'s crust measured by weight, making it the sixth most abundant element overall and the most abundant alkali metal. Potassium makes up approximately 1.5% of the Earth\'s crust and is the seventh most abundant element. Sodium is found in many different minerals, of which the most common is ordinary salt (sodium chloride), which occurs in vast quantities dissolved in seawater. Other solid deposits include halite, amphibole, cryolite, nitratine, and zeolite. Many of these solid deposits occur as a result of ancient seas evaporating, which still occurs now in places such as Utah\'s Great Salt Lake and the Dead Sea. Despite their near-equal abundance in Earth\'s crust, sodium is far more common than potassium in the ocean, both because potassium\'s larger size makes its salts less soluble, and because potassium is bound by silicates in soil and what potassium leaches is absorbed far more readily by plant life than sodium.
Despite its chemical similarity, lithium typically does not occur together with sodium or potassium due to its smaller size. Due to its relatively low reactivity, it can be found in seawater in large amounts; it is estimated that lithium concentration in seawater is approximately 0.14 to 0.25 parts per million (ppm) or 25 micromolar. Its diagonal relationship with magnesium often allows it to replace magnesium in ferromagnesium minerals, where its crustal concentration is about 18 ppm, comparable to that of gallium and niobium. Commercially, the most important lithium mineral is spodumene, which occurs in large deposits worldwide.
Rubidium is approximately as abundant as zinc and more abundant than copper. It occurs naturally in the minerals leucite, pollucite, carnallite, zinnwaldite, and lepidolite, although none of these contain only rubidium and no other alkali metals. Caesium is more abundant than some commonly known elements, such as antimony, cadmium, tin, and tungsten, but is much less abundant than rubidium.
Francium-223, the only naturally occurring isotope of francium, is the product of the alpha decay of actinium-227 and can be found in trace amounts in uranium minerals. In a given sample of uranium, there is estimated to be only one francium atom for every 10^18^ uranium atoms. It has been calculated that there are at most 30 grams of francium in the earth\'s crust at any time, due to its extremely short half-life of 22 minutes.
## Properties
### Physical and chemical {#physical_and_chemical}
The physical and chemical properties of the alkali metals can be readily explained by their having an ns^1^ valence electron configuration, which results in weak metallic bonding. Hence, all the alkali metals are soft and have low densities, melting and boiling points, as well as heats of sublimation, vaporisation, and dissociation. They all crystallise in the body-centered cubic crystal structure, and have distinctive flame colours because their outer s electron is very easily excited. Indeed, these flame test colours are the most common way of identifying them since all their salts with common ions are soluble. The ns^1^ configuration also results in the alkali metals having very large atomic and ionic radii, as well as very high thermal and electrical conductivity. Their chemistry is dominated by the loss of their lone valence electron in the outermost s-orbital to form the +1 oxidation state, due to the ease of ionising this electron and the very high second ionisation energy. Most of the chemistry has been observed only for the first five members of the group. The chemistry of francium is not well established due to its extreme radioactivity; thus, the presentation of its properties here is limited. What little is known about francium shows that it is very close in behaviour to caesium, as expected. The physical properties of francium are even sketchier because the bulk element has never been observed; hence any data that may be found in the literature are certainly speculative extrapolations.
+--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+----------------+--------------+--------------+----------------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| Name | Lithium | Sodium | Potassium | Rubidium | Caesium | Francium |
+==================================================================================================================================================================================================================================================================================================================================================================================================================================================================================================================================================================================================================================================================================================================================================================================================================================================================================================================================================+==========================================================================================================================================================================================================================================================+================+==============+==============+================+==============================================================================================================================================================================================================================================================================================================================================================================================================================================================================================================================================================================================================================================================================================================================================================================================================================================================================================================================================================================================================================================================================================================================================================================================================================================+
| Atomic number | 3 | 11 | 19 | 37 | 55 | 87 |
+--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+----------------+--------------+--------------+----------------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| Standard atomic weight`{{refn|The number given in [[bracket|parentheses]] refers to the [[standard uncertainty|measurement uncertainty]]. This uncertainty applies to the [[significant figure|least significant figure]](s) of the number prior to the parenthesised value (ie. counting from rightmost digit to left). For instance, {{val|1.00794|(7)}} stands for {{val|1.00794|0.00007}}, while {{val|1.00794|(72)}} stands for {{val|1.00794|0.00072}}.<ref>{{cite web|url=http://physics.nist.gov/cgi-bin/cuu/Info/Constants/definitions.html|title=Standard Uncertainty and Relative Standard Uncertainty|work=[[CODATA]] reference|publisher=[[National Institute of Standards and Technology]]|access-date=26 September 2011|archive-date=16 October 2011|archive-url=https://web.archive.org/web/20111016021440/http://physics.nist.gov/cgi-bin/cuu/Info/Constants/definitions.html|url-status=live}}</ref>|group=note}}`{=mediawiki} | 6.94(1)`{{refn|The value listed is the conventional value suitable for trade and commerce; the actual value may range from 6.938 to 6.997 depending on the isotopic composition of the sample.<ref name="atomicweights2009" />|group=note}}`{=mediawiki} | 22.98976928(2) | 39.0983(1) | 85.4678(3) | 132.9054519(2) | \[223\]`{{refn|The element does not have any stable [[nuclide]]s, and a value in brackets indicates the [[mass number]] of the longest-lived [[isotope]] of the element.<ref name="atomicweights2007" /><ref name="atomicweights2009" />|group=note}}`{=mediawiki} |
+--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+----------------+--------------+--------------+----------------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| Electron configuration | \[He\] 2s^1^ | \[Ne\] 3s^1^ | \[Ar\] 4s^1^ | \[Kr\] 5s^1^ | \[Xe\] 6s^1^ | \[Rn\] 7s^1^ |
+--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+----------------+--------------+--------------+----------------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| Melting point (°C) | 180.54 | 97.72 | 63.38 | 39.31 | 28.44 | ? |
+--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+----------------+--------------+--------------+----------------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| Boiling point (°C) | 1342 | 883 | 759 | 688 | 671 | ? |
+--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+----------------+--------------+--------------+----------------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| Density (g·cm^−3^) | 0.534 | 0.968 | 0.89 | 1.532 | 1.93 | ? |
+--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+----------------+--------------+--------------+----------------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| Heat of fusion (kJ·mol^−1^) | 3.00 | 2.60 | 2.321 | 2.19 | 2.09 | ? |
+--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+----------------+--------------+--------------+----------------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| Heat of vaporisation (kJ·mol^−1^) | 136 | 97.42 | 79.1 | 69 | 66.1 | ? |
+--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+----------------+--------------+--------------+----------------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| Heat of formation of monatomic gas (kJ·mol^−1^) | 162 | 108 | 89.6 | 82.0 | 78.2 | ? |
+--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+----------------+--------------+--------------+----------------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| Electrical resistivity at 25 °C (nΩ·cm) | 94.7 | 48.8 | 73.9 | 131 | 208 | ? |
+--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+----------------+--------------+--------------+----------------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| Atomic radius (pm) | 152 | 186 | 227 | 248 | 265 | ? |
+--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+----------------+--------------+--------------+----------------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| Ionic radius of hexacoordinate M^+^ ion (pm) | 76 | 102 | 138 | 152 | 167 | ? |
+--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+----------------+--------------+--------------+----------------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| First ionisation energy (kJ·mol^−1^) | 520.2 | 495.8 | 418.8 | 403.0 | 375.7 | 392.8 |
+--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+----------------+--------------+--------------+----------------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| Electron affinity (kJ·mol^−1^) | 59.62 | 52.87 | 48.38 | 46.89 | 45.51 | ? |
+--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+----------------+--------------+--------------+----------------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| Enthalpy of dissociation of M~2~ (kJ·mol^−1^) | 106.5 | 73.6 | 57.3 | 45.6 | 44.77 | ? |
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| Pauling electronegativity | 0.98 | 0.93 | 0.82 | 0.82 | 0.79 | ?`{{refn|[[Linus Pauling]] estimated the electronegativity of francium at 0.7 on the [[Pauling scale]], the same as caesium;<ref>{{cite book |last= Pauling |first= Linus |title= The Nature of the Chemical Bond|url= https://archive.org/details/natureofchemical00paul |url-access= registration |edition= Third |author-link= Linus Pauling |publisher= Cornell University Press |year= 1960 |isbn= 978-0-8014-0333-0 |page= [https://archive.org/details/natureofchemical00paul/page/93 93]}}</ref> the value for caesium has since been refined to 0.79, although there are no experimental data to allow a refinement of the value for francium.<ref>{{cite journal |last=Allred|first=A. L. |year= 1961 |journal= J. Inorg. Nucl. Chem.|volume= 17 |issue= 3–4 |pages= 215–221 |title= Electronegativity values from thermochemical data |doi= 10.1016/0022-1902(61)80142-5}}</ref> Francium has a slightly higher ionisation energy than caesium,<ref name="andreev" /> 392.811(4) kJ/mol as opposed to 375.7041(2) kJ/mol for caesium, as would be expected from [[relativistic effects]], and this would imply that caesium is the less electronegative of the two.|name=Fr-electronegativity|group=note}}`{=mediawiki} |
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| Allen electronegativity | 0.91 | 0.87 | 0.73 | 0.71 | 0.66 | 0.67 |
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| Standard electrode potential (*E*°(M^+^→M^0^); V) | −3.04 | −2.71 | −2.93 | −2.98 | −3.03 | ? |
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| Flame test colour\ | Crimson\ | Yellow\ | Violet\ | Red-violet\ | Blue\ | ? |
| Principal emission/absorption wavelength (nm) | 670.8 | 589.2 | 766.5 | 780.0 | 455.5 | |
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: Properties of the alkali metals
The alkali metals are more similar to each other than the elements in any other group are to each other. Indeed, the similarity is so great that it is quite difficult to separate potassium, rubidium, and caesium, due to their similar ionic radii; lithium and sodium are more distinct. For instance, when moving down the table, all known alkali metals show increasing atomic radius, decreasing electronegativity, increasing reactivity, and decreasing melting and boiling points as well as heats of fusion and vaporisation. In general, their densities increase when moving down the table, with the exception that potassium is less dense than sodium. One of the very few properties of the alkali metals that does not display a very smooth trend is their reduction potentials: lithium\'s value is anomalous, being more negative than the others. This is because the Li^+^ ion has a very high hydration energy in the gas phase: though the lithium ion disrupts the structure of water significantly, causing a higher change in entropy, this high hydration energy is enough to make the reduction potentials indicate it as being the most electropositive alkali metal, despite the difficulty of ionising it in the gas phase.
The stable alkali metals are all silver-coloured metals except for caesium, which has a pale golden tint: it is one of only three metals that are clearly coloured (the other two being copper and gold). Additionally, the heavy alkaline earth metals calcium, strontium, and barium, as well as the divalent lanthanides europium and ytterbium, are pale yellow, though the colour is much less prominent than it is for caesium. Their lustre tarnishes rapidly in air due to oxidation.
All the alkali metals are highly reactive and are never found in elemental forms in nature. Because of this, they are usually stored in mineral oil or kerosene (paraffin oil). They react aggressively with the halogens to form the alkali metal halides, which are white ionic crystalline compounds that are all soluble in water except lithium fluoride (LiF). The alkali metals also react with water to form strongly alkaline hydroxides and thus should be handled with great care. The heavier alkali metals react more vigorously than the lighter ones; for example, when dropped into water, caesium produces a larger explosion than potassium if the same number of moles of each metal is used. The alkali metals have the lowest first ionisation energies in their respective periods of the periodic table because of their low effective nuclear charge and the ability to attain a noble gas configuration by losing just one electron. Not only do the alkali metals react with water, but also with proton donors like alcohols and phenols, gaseous ammonia, and alkynes, the last demonstrating the phenomenal degree of their reactivity. Their great power as reducing agents makes them very useful in liberating other metals from their oxides or halides.
The second ionisation energy of all of the alkali metals is very high as it is in a full shell that is also closer to the nucleus; thus, they almost always lose a single electron, forming cations. The alkalides are an exception: they are unstable compounds which contain alkali metals in a −1 oxidation state, which is very unusual as before the discovery of the alkalides, the alkali metals were not expected to be able to form anions and were thought to be able to appear in salts only as cations. The alkalide anions have filled s-subshells, which gives them enough stability to exist. All the stable alkali metals except lithium are known to be able to form alkalides, and the alkalides have much theoretical interest due to their unusual stoichiometry and low ionisation potentials. Alkalides are chemically similar to the electrides, which are salts with trapped electrons acting as anions. A particularly striking example of an alkalide is \"inverse sodium hydride\", H^+^Na^−^ (both ions being complexed), as opposed to the usual sodium hydride, Na^+^H^−^: it is unstable in isolation, due to its high energy resulting from the displacement of two electrons from hydrogen to sodium, although several derivatives are predicted to be metastable or stable.
In aqueous solution, the alkali metal ions form aqua ions of the formula \[M(H~2~O)~*n*~\]^+^, where *n* is the solvation number. Their coordination numbers and shapes agree well with those expected from their ionic radii. In aqueous solution the water molecules directly attached to the metal ion are said to belong to the first coordination sphere, also known as the first, or primary, solvation shell. The bond between a water molecule and the metal ion is a dative covalent bond, with the oxygen atom donating both electrons to the bond. Each coordinated water molecule may be attached by hydrogen bonds to other water molecules. The latter are said to reside in the second coordination sphere. However, for the alkali metal cations, the second coordination sphere is not well-defined as the +1 charge on the cation is not high enough to polarise the water molecules in the primary solvation shell enough for them to form strong hydrogen bonds with those in the second coordination sphere, producing a more stable entity. The solvation number for Li^+^ has been experimentally determined to be 4, forming the tetrahedral \[Li(H~2~O)~4~\]^+^: while solvation numbers of 3 to 6 have been found for lithium aqua ions, solvation numbers less than 4 may be the result of the formation of contact ion pairs, and the higher solvation numbers may be interpreted in terms of water molecules that approach \[Li(H~2~O)~4~\]^+^ through a face of the tetrahedron, though molecular dynamic simulations may indicate the existence of an octahedral hexaaqua ion. There are also probably six water molecules in the primary solvation sphere of the sodium ion, forming the octahedral \[Na(H~2~O)~6~\]^+^ ion. While it was previously thought that the heavier alkali metals also formed octahedral hexaaqua ions, it has since been found that potassium and rubidium probably form the \[K(H~2~O)~8~\]^+^ and \[Rb(H~2~O)~8~\]^+^ ions, which have the square antiprismatic structure, and that caesium forms the 12-coordinate \[Cs(H~2~O)~12~\]^+^ ion. `{{clear left}}`{=mediawiki}
#### Lithium
The chemistry of lithium shows several differences from that of the rest of the group as the small Li^+^ cation polarises anions and gives its compounds a more covalent character. Lithium and magnesium have a diagonal relationship due to their similar atomic radii, so that they show some similarities. For example, lithium forms a stable nitride, a property common among all the alkaline earth metals (magnesium\'s group) but unique among the alkali metals. In addition, among their respective groups, only lithium and magnesium form organometallic compounds with significant covalent character (e.g. LiMe and MgMe~2~).
Lithium fluoride is the only alkali metal halide that is poorly soluble in water, and lithium hydroxide is the only alkali metal hydroxide that is not deliquescent. Conversely, lithium perchlorate and other lithium salts with large anions that cannot be polarised are much more stable than the analogous compounds of the other alkali metals, probably because Li^+^ has a high solvation energy. This effect also means that most simple lithium salts are commonly encountered in hydrated form, because the anhydrous forms are extremely hygroscopic: this allows salts like lithium chloride and lithium bromide to be used in dehumidifiers and air-conditioners.
#### Francium
Francium is also predicted to show some differences due to its high atomic weight, causing its electrons to travel at considerable fractions of the speed of light and thus making relativistic effects more prominent. In contrast to the trend of decreasing electronegativities and ionisation energies of the alkali metals, francium\'s electronegativity and ionisation energy are predicted to be higher than caesium\'s due to the relativistic stabilisation of the 7s electrons; also, its atomic radius is expected to be abnormally low. Thus, contrary to expectation, caesium is the most reactive of the alkali metals, not francium. All known physical properties of francium also deviate from the clear trends going from lithium to caesium, such as the first ionisation energy, electron affinity, and anion polarisability, though due to the paucity of known data about francium many sources give extrapolated values, ignoring that relativistic effects make the trend from lithium to caesium become inapplicable at francium. Some of the few properties of francium that have been predicted taking relativity into account are the electron affinity (47.2 kJ/mol) and the enthalpy of dissociation of the Fr~2~ molecule (42.1 kJ/mol). The CsFr molecule is polarised as Cs^+^Fr^−^, showing that the 7s subshell of francium is much more strongly affected by relativistic effects than the 6s subshell of caesium. Additionally, francium superoxide (FrO~2~) is expected to have significant covalent character, unlike the other alkali metal superoxides, because of bonding contributions from the 6p electrons of francium.
### Nuclear
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| Z\ | Alkali metal\ | Stable\ | *Decays*\ | *unstable: italics* |
| | | | | |
| | | | | odd--odd isotopes coloured pink |
+==========================================================================================================================================================================================================================================================+===============+=========+===========+==========================================================================+
| 3 | lithium | 2 | --- | |
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| 11 | sodium | 1 | --- | |
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| 19 | potassium | 2 | 1 | |
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| 37 | rubidium | 1 | 1 | |
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| 55 | caesium | 1 | --- | |
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| 87 | francium | --- | --- | *No primordial isotopes*\ |
| | | | | (*`{{SimpleNuclide|francium|223}}`{=mediawiki}* is a radiogenic nuclide) |
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| Radioactive: `{{nowrap|<sup>40</sup>K, [[half-life|t<sub>1/2</sub>]] 1.25 billion years;}}`{=mediawiki} `{{nowrap|<sup>87</sup>Rb, t<sub>1/2</sub> 49 billion years;}}`{=mediawiki} `{{nowrap|<sup>223</sup>Fr, t<sub>1/2</sub> 22.0 min.}}`{=mediawiki} | | | | |
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: Primordial isotopes of the alkali metals
All the alkali metals have odd atomic numbers; hence, their isotopes must be either odd--odd (both proton and neutron number are odd) or odd--even (proton number is odd, but neutron number is even). Odd--odd nuclei have even mass numbers, whereas odd--even nuclei have odd mass numbers. Odd--odd primordial nuclides are rare because most odd--odd nuclei are highly unstable with respect to beta decay, because the decay products are even--even, and are therefore more strongly bound, due to nuclear pairing effects.
Due to the great rarity of odd--odd nuclei, almost all the primordial isotopes of the alkali metals are odd--even (the exceptions being the light stable isotope lithium-6 and the long-lived radioisotope potassium-40). For a given odd mass number, there can be only a single beta-stable nuclide, since there is not a difference in binding energy between even--odd and odd--even comparable to that between even--even and odd--odd, leaving other nuclides of the same mass number (isobars) free to beta decay toward the lowest-mass nuclide. An effect of the instability of an odd number of either type of nucleons is that odd-numbered elements, such as the alkali metals, tend to have fewer stable isotopes than even-numbered elements. Of the 26 monoisotopic elements that have only a single stable isotope, all but one have an odd atomic number and all but one also have an even number of neutrons. Beryllium is the single exception to both rules, due to its low atomic number.
All of the alkali metals except lithium and caesium have at least one naturally occurring radioisotope: sodium-22 and sodium-24 are trace radioisotopes produced cosmogenically, potassium-40 and rubidium-87 have very long half-lives and thus occur naturally, and all isotopes of francium are radioactive. Caesium was also thought to be radioactive in the early 20th century, although it has no naturally occurring radioisotopes. (Francium had not been discovered yet at that time.) The natural long-lived radioisotope of potassium, potassium-40, makes up about 0.012% of natural potassium, and thus natural potassium is weakly radioactive. This natural radioactivity became a basis for a mistaken claim of the discovery for element 87 (the next alkali metal after caesium) in 1925. Natural rubidium is similarly slightly radioactive, with 27.83% being the long-lived radioisotope rubidium-87.
Caesium-137, with a half-life of 30.17 years, is one of the two principal medium-lived fission products, along with strontium-90, which are responsible for most of the radioactivity of spent nuclear fuel after several years of cooling, up to several hundred years after use. It constitutes most of the radioactivity still left from the Chernobyl accident. Caesium-137 undergoes high-energy beta decay and eventually becomes stable barium-137. It is a strong emitter of gamma radiation. Caesium-137 has a very low rate of neutron capture and cannot be feasibly disposed of in this way, but must be allowed to decay. Caesium-137 has been used as a tracer in hydrologic studies, analogous to the use of tritium. Small amounts of caesium-134 and caesium-137 were released into the environment during nearly all nuclear weapon tests and some nuclear accidents, most notably the Goiânia accident and the Chernobyl disaster. As of 2005, caesium-137 is the principal source of radiation in the zone of alienation around the Chernobyl nuclear power plant. Its chemical properties as one of the alkali metals make it one of the most problematic of the short-to-medium-lifetime fission products because it easily moves and spreads in nature due to the high water solubility of its salts, and is taken up by the body, which mistakes it for its essential congeners sodium and potassium.
## Periodic trends {#periodic_trends}
The alkali metals are more similar to each other than the elements in any other group are to each other. For instance, when moving down the table, all known alkali metals show increasing atomic radius, decreasing electronegativity, increasing reactivity, and decreasing melting and boiling points as well as heats of fusion and vaporisation. In general, their densities increase when moving down the table, with the exception that potassium is less dense than sodium.
### Atomic and ionic radii {#atomic_and_ionic_radii}
The atomic radii of the alkali metals increase going down the group. Because of the shielding effect, when an atom has more than one electron shell, each electron feels electric repulsion from the other electrons as well as electric attraction from the nucleus. In the alkali metals, the outermost electron only feels a net charge of +1, as some of the nuclear charge (which is equal to the atomic number) is cancelled by the inner electrons; the number of inner electrons of an alkali metal is always one less than the nuclear charge. Therefore, the only factor which affects the atomic radius of the alkali metals is the number of electron shells. Since this number increases down the group, the atomic radius must also increase down the group.
The ionic radii of the alkali metals are much smaller than their atomic radii. This is because the outermost electron of the alkali metals is in a different electron shell than the inner electrons, and thus when it is removed the resulting atom has one fewer electron shell and is smaller. Additionally, the effective nuclear charge has increased, and thus the electrons are attracted more strongly towards the nucleus and the ionic radius decreases.
### First ionisation energy {#first_ionisation_energy}
thumb\|upright=2.7\|Periodic trend for ionisation energy: each period begins at a minimum for the alkali metals, and ends at a maximum for the noble gases. Predicted values are used for elements beyond 104. The first ionisation energy of an element or molecule is the energy required to move the most loosely held electron from one mole of gaseous atoms of the element or molecules to form one mole of gaseous ions with electric charge +1. The factors affecting the first ionisation energy are the nuclear charge, the amount of shielding by the inner electrons and the distance from the most loosely held electron from the nucleus, which is always an outer electron in main group elements. The first two factors change the effective nuclear charge the most loosely held electron feels. Since the outermost electron of alkali metals always feels the same effective nuclear charge (+1), the only factor which affects the first ionisation energy is the distance from the outermost electron to the nucleus. Since this distance increases down the group, the outermost electron feels less attraction from the nucleus and thus the first ionisation energy decreases. This trend is broken in francium due to the relativistic stabilisation and contraction of the 7s orbital, bringing francium\'s valence electron closer to the nucleus than would be expected from non-relativistic calculations. This makes francium\'s outermost electron feel more attraction from the nucleus, increasing its first ionisation energy slightly beyond that of caesium.
The second ionisation energy of the alkali metals is much higher than the first as the second-most loosely held electron is part of a fully filled electron shell and is thus difficult to remove.
### Reactivity
The reactivities of the alkali metals increase going down the group. This is the result of a combination of two factors: the first ionisation energies and atomisation energies of the alkali metals. Because the first ionisation energy of the alkali metals decreases down the group, it is easier for the outermost electron to be removed from the atom and participate in chemical reactions, thus increasing reactivity down the group. The atomisation energy measures the strength of the metallic bond of an element, which falls down the group as the atoms increase in radius and thus the metallic bond must increase in length, making the delocalised electrons further away from the attraction of the nuclei of the heavier alkali metals. Adding the atomisation and first ionisation energies gives a quantity closely related to (but not equal to) the activation energy of the reaction of an alkali metal with another substance. This quantity decreases going down the group, and so does the activation energy; thus, chemical reactions can occur faster and the reactivity increases down the group.
### Electronegativity
thumb\|upright=1.25\|Periodic variation of Pauling electronegativities as one descends the main groups of the periodic table from the second to the sixth period.
Electronegativity is a chemical property that describes the tendency of an atom or a functional group to attract electrons (or electron density) towards itself. If the bond between sodium and chlorine in sodium chloride were covalent, the pair of shared electrons would be attracted to the chlorine because the effective nuclear charge on the outer electrons is +7 in chlorine but is only +1 in sodium. The electron pair is attracted so close to the chlorine atom that they are practically transferred to the chlorine atom (an ionic bond). However, if the sodium atom was replaced by a lithium atom, the electrons will not be attracted as close to the chlorine atom as before because the lithium atom is smaller, making the electron pair more strongly attracted to the closer effective nuclear charge from lithium. Hence, the larger alkali metal atoms (further down the group) will be less electronegative as the bonding pair is less strongly attracted towards them. As mentioned previously, francium is expected to be an exception.
Because of the higher electronegativity of lithium, some of its compounds have a more covalent character. For example, lithium iodide (LiI) will dissolve in organic solvents, a property of most covalent compounds. Lithium fluoride (LiF) is the only alkali halide that is not soluble in water, and lithium hydroxide (LiOH) is the only alkali metal hydroxide that is not deliquescent.
### Melting and boiling points {#melting_and_boiling_points}
The melting point of a substance is the point where it changes state from solid to liquid while the boiling point of a substance (in liquid state) is the point where the vapour pressure of the liquid equals the environmental pressure surrounding the liquid and all the liquid changes state to gas. As a metal is heated to its melting point, the metallic bonds keeping the atoms in place weaken so that the atoms can move around, and the metallic bonds eventually break completely at the metal\'s boiling point. Therefore, the falling melting and boiling points of the alkali metals indicate that the strength of the metallic bonds of the alkali metals decreases down the group. This is because metal atoms are held together by the electromagnetic attraction from the positive ions to the delocalised electrons. As the atoms increase in size going down the group (because their atomic radius increases), the nuclei of the ions move further away from the delocalised electrons and hence the metallic bond becomes weaker so that the metal can more easily melt and boil, thus lowering the melting and boiling points. The increased nuclear charge is not a relevant factor due to the shielding effect.
### Density
The alkali metals all have the same crystal structure (body-centred cubic) and thus the only relevant factors are the number of atoms that can fit into a certain volume and the mass of one of the atoms, since density is defined as mass per unit volume. The first factor depends on the volume of the atom and thus the atomic radius, which increases going down the group; thus, the volume of an alkali metal atom increases going down the group. The mass of an alkali metal atom also increases going down the group. Thus, the trend for the densities of the alkali metals depends on their atomic weights and atomic radii; if figures for these two factors are known, the ratios between the densities of the alkali metals can then be calculated. The resultant trend is that the densities of the alkali metals increase down the table, with an exception at potassium. Due to having the lowest atomic weight and the largest atomic radius of all the elements in their periods, the alkali metals are the least dense metals in the periodic table. Lithium, sodium, and potassium are the only three metals in the periodic table that are less dense than water: in fact, lithium is the least dense known solid at room temperature.
## Compounds
The alkali metals form complete series of compounds with all usually encountered anions, which well illustrate group trends. These compounds can be described as involving the alkali metals losing electrons to acceptor species and forming monopositive ions. This description is most accurate for alkali halides and becomes less and less accurate as cationic and anionic charge increase, and as the anion becomes larger and more polarisable. For instance, ionic bonding gives way to metallic bonding along the series NaCl, Na~2~O, Na~2~S, Na~3~P, Na~3~As, Na~3~Sb, Na~3~Bi, Na.
### Hydroxides
All the alkali metals react vigorously or explosively with cold water, producing an aqueous solution of a strongly basic alkali metal hydroxide and releasing hydrogen gas. This reaction becomes more vigorous going down the group: lithium reacts steadily with effervescence, but sodium and potassium can ignite, and rubidium and caesium sink in water and generate hydrogen gas so rapidly that shock waves form in the water that may shatter glass containers. When an alkali metal is dropped into water, it produces an explosion, of which there are two separate stages. The metal reacts with the water first, breaking the hydrogen bonds in the water and producing hydrogen gas; this takes place faster for the more reactive heavier alkali metals. Second, the heat generated by the first part of the reaction often ignites the hydrogen gas, causing it to burn explosively into the surrounding air. This secondary hydrogen gas explosion produces the visible flame above the bowl of water, lake or other body of water, not the initial reaction of the metal with water (which tends to happen mostly under water). The alkali metal hydroxides are the most basic known hydroxides.
Recent research has suggested that the explosive behavior of alkali metals in water is driven by a Coulomb explosion rather than solely by rapid generation of hydrogen itself. All alkali metals melt as a part of the reaction with water. Water molecules ionise the bare metallic surface of the liquid metal, leaving a positively charged metal surface and negatively charged water ions. The attraction between the charged metal and water ions will rapidly increase the surface area, causing an exponential increase of ionisation. When the repulsive forces within the liquid metal surface exceeds the forces of the surface tension, it vigorously explodes.
The hydroxides themselves are the most basic hydroxides known, reacting with acids to give salts and with alcohols to give oligomeric alkoxides. They easily react with carbon dioxide to form carbonates or bicarbonates, or with hydrogen sulfide to form sulfides or bisulfides, and may be used to separate thiols from petroleum. They react with amphoteric oxides: for example, the oxides of aluminium, zinc, tin, and lead react with the alkali metal hydroxides to give aluminates, zincates, stannates, and plumbates. Silicon dioxide is acidic, and thus the alkali metal hydroxides can also attack silicate glass.
### Intermetallic compounds {#intermetallic_compounds}
The alkali metals form many intermetallic compounds with each other and the elements from groups 2 to 13 in the periodic table of varying stoichiometries, such as the sodium amalgams with mercury, including Na~5~Hg~8~ and Na~3~Hg. Some of these have ionic characteristics: taking the alloys with gold, the most electronegative of metals, as an example, NaAu and KAu are metallic, but RbAu and CsAu are semiconductors. NaK is an alloy of sodium and potassium that is very useful because it is liquid at room temperature, although precautions must be taken due to its extreme reactivity towards water and air. The eutectic mixture melts at −12.6 °C. An alloy of 41% caesium, 47% sodium, and 12% potassium has the lowest known melting point of any metal or alloy, −78 °C.
### Compounds with the group 13 elements {#compounds_with_the_group_13_elements}
The intermetallic compounds of the alkali metals with the heavier group 13 elements (aluminium, gallium, indium, and thallium), such as NaTl, are poor conductors or semiconductors, unlike the normal alloys with the preceding elements, implying that the alkali metal involved has lost an electron to the Zintl anions involved. Nevertheless, while the elements in group 14 and beyond tend to form discrete anionic clusters, group 13 elements tend to form polymeric ions with the alkali metal cations located between the giant ionic lattice. For example, NaTl consists of a polymeric anion (---Tl^−^---)~n~ with a covalent diamond cubic structure with Na^+^ ions located between the anionic lattice. The larger alkali metals cannot fit similarly into an anionic lattice and tend to force the heavier group 13 elements to form anionic clusters.
Boron is a special case, being the only nonmetal in group 13. The alkali metal borides tend to be boron-rich, involving appreciable boron--boron bonding involving deltahedral structures, and are thermally unstable due to the alkali metals having a very high vapour pressure at elevated temperatures. This makes direct synthesis problematic because the alkali metals do not react with boron below 700 °C, and thus this must be accomplished in sealed containers with the alkali metal in excess. Furthermore, exceptionally in this group, reactivity with boron decreases down the group: lithium reacts completely at 700 °C, but sodium at 900 °C and potassium not until 1200 °C, and the reaction is instantaneous for lithium but takes hours for potassium. Rubidium and caesium borides have not even been characterised. Various phases are known, such as LiB~10~, NaB~6~, NaB~15~, and KB~6~. Under high pressure the boron--boron bonding in the lithium borides changes from following Wade\'s rules to forming Zintl anions like the rest of group 13.
### Compounds with the group 14 elements {#compounds_with_the_group_14_elements}
Lithium and sodium react with carbon to form acetylides, Li~2~C~2~ and Na~2~C~2~, which can also be obtained by reaction of the metal with acetylene. Potassium, rubidium, and caesium react with graphite; their atoms are intercalated between the hexagonal graphite layers, forming graphite intercalation compounds of formulae MC~60~ (dark grey, almost black), MC~48~ (dark grey, almost black), MC~36~ (blue), MC~24~ (steel blue), and MC~8~ (bronze) (M = K, Rb, or Cs). These compounds are over 200 times more electrically conductive than pure graphite, suggesting that the valence electron of the alkali metal is transferred to the graphite layers (e.g. `{{chem2|M+C8-}}`{=mediawiki}). Upon heating of KC~8~, the elimination of potassium atoms results in the conversion in sequence to KC~24~, KC~36~, KC~48~ and finally KC~60~. KC~8~ is a very strong reducing agent and is pyrophoric and explodes on contact with water. While the larger alkali metals (K, Rb, and Cs) initially form MC~8~, the smaller ones initially form MC~6~, and indeed they require reaction of the metals with graphite at high temperatures around 500 °C to form. Apart from this, the alkali metals are such strong reducing agents that they can even reduce buckminsterfullerene to produce solid fullerides M~*n*~C~60~; sodium, potassium, rubidium, and caesium can form fullerides where *n* = 2, 3, 4, or 6, and rubidium and caesium additionally can achieve *n* = 1.
When the alkali metals react with the heavier elements in the carbon group (silicon, germanium, tin, and lead), ionic substances with cage-like structures are formed, such as the silicides M~4~Si~4~ (M = K, Rb, or Cs), which contains M^+^ and tetrahedral `{{chem2|Si4(4-)}}`{=mediawiki} ions. The chemistry of alkali metal germanides, involving the germanide ion Ge^4−^ and other cluster (Zintl) ions such as `{{chem2|Ge4(2-)}}`{=mediawiki}, `{{chem2|Ge9(4-)}}`{=mediawiki}, `{{chem2|Ge9(2-)}}`{=mediawiki}, and \[(Ge~9~)~2~\]^6−^, is largely analogous to that of the corresponding silicides. Alkali metal stannides are mostly ionic, sometimes with the stannide ion (Sn^4−^), and sometimes with more complex Zintl ions such as `{{chem2|Sn9(4-)}}`{=mediawiki}, which appears in tetrapotassium nonastannide (K~4~Sn~9~). The monatomic plumbide ion (Pb^4−^) is unknown, and indeed its formation is predicted to be energetically unfavourable; alkali metal plumbides have complex Zintl ions, such as `{{chem2|Pb9(4-)}}`{=mediawiki}. These alkali metal germanides, stannides, and plumbides may be produced by reducing germanium, tin, and lead with sodium metal in liquid ammonia.
### Nitrides and pnictides {#nitrides_and_pnictides}
Lithium, the lightest of the alkali metals, is the only alkali metal which reacts with nitrogen at standard conditions, and its nitride is the only stable alkali metal nitride. Nitrogen is an unreactive gas because breaking the strong triple bond in the dinitrogen molecule (N~2~) requires a lot of energy. The formation of an alkali metal nitride would consume the ionisation energy of the alkali metal (forming M^+^ ions), the energy required to break the triple bond in N~2~ and the formation of N^3−^ ions, and all the energy released from the formation of an alkali metal nitride is from the lattice energy of the alkali metal nitride. The lattice energy is maximised with small, highly charged ions; the alkali metals do not form highly charged ions, only forming ions with a charge of +1, so only lithium, the smallest alkali metal, can release enough lattice energy to make the reaction with nitrogen exothermic, forming lithium nitride. The reactions of the other alkali metals with nitrogen would not release enough lattice energy and would thus be endothermic, so they do not form nitrides at standard conditions. Sodium nitride (Na~3~N) and potassium nitride (K~3~N), while existing, are extremely unstable, being prone to decomposing back into their constituent elements, and cannot be produced by reacting the elements with each other at standard conditions. Steric hindrance forbids the existence of rubidium or caesium nitride. However, sodium and potassium form colourless azide salts involving the linear `{{chem2|N3-}}`{=mediawiki} anion; due to the large size of the alkali metal cations, they are thermally stable enough to be able to melt before decomposing.
All the alkali metals react readily with phosphorus and arsenic to form phosphides and arsenides with the formula M~3~Pn (where M represents an alkali metal and Pn represents a pnictogen -- phosphorus, arsenic, antimony, or bismuth). This is due to the greater size of the P^3−^ and As^3−^ ions, so that less lattice energy needs to be released for the salts to form. These are not the only phosphides and arsenides of the alkali metals: for example, potassium has nine different known phosphides, with formulae K~3~P, K~4~P~3~, K~5~P~4~, KP, K~4~P~6~, K~3~P~7~, K~3~P~11~, KP~10.3~, and KP~15~. While most metals form arsenides, only the alkali and alkaline earth metals form mostly ionic arsenides. The structure of Na~3~As is complex with unusually short Na--Na distances of 328--330 pm which are shorter than in sodium metal, and this indicates that even with these electropositive metals the bonding cannot be straightforwardly ionic. Other alkali metal arsenides not conforming to the formula M~3~As are known, such as LiAs, which has a metallic lustre and electrical conductivity indicating the presence of some metallic bonding. The antimonides are unstable and reactive as the Sb^3−^ ion is a strong reducing agent; reaction of them with acids form the toxic and unstable gas stibine (SbH~3~). Indeed, they have some metallic properties, and the alkali metal antimonides of stoichiometry MSb involve antimony atoms bonded in a spiral Zintl structure. Bismuthides are not even wholly ionic; they are intermetallic compounds containing partially metallic and partially ionic bonds.
### Oxides and chalcogenides {#oxides_and_chalcogenides}
All the alkali metals react vigorously with oxygen at standard conditions. They form various types of oxides, such as simple oxides (containing the O^2−^ ion), peroxides (containing the `{{chem2|O2(2-)}}`{=mediawiki} ion, where there is a single bond between the two oxygen atoms), superoxides (containing the `{{chem2|O2-}}`{=mediawiki} ion), and many others. Lithium burns in air to form lithium oxide, but sodium reacts with oxygen to form a mixture of sodium oxide and sodium peroxide. Potassium forms a mixture of potassium peroxide and potassium superoxide, while rubidium and caesium form the superoxide exclusively. Their reactivity increases going down the group: while lithium, sodium and potassium merely burn in air, rubidium and caesium are pyrophoric (spontaneously catch fire in air).
The smaller alkali metals tend to polarise the larger anions (the peroxide and superoxide) due to their small size. This attracts the electrons in the more complex anions towards one of its constituent oxygen atoms, forming an oxide ion and an oxygen atom. This causes lithium to form the oxide exclusively on reaction with oxygen at room temperature. This effect becomes drastically weaker for the larger sodium and potassium, allowing them to form the less stable peroxides. Rubidium and caesium, at the bottom of the group, are so large that even the least stable superoxides can form. Because the superoxide releases the most energy when formed, the superoxide is preferentially formed for the larger alkali metals where the more complex anions are not polarised. The oxides and peroxides for these alkali metals do exist, but do not form upon direct reaction of the metal with oxygen at standard conditions. In addition, the small size of the Li^+^ and O^2−^ ions contributes to their forming a stable ionic lattice structure. Under controlled conditions, however, all the alkali metals, with the exception of francium, are known to form their oxides, peroxides, and superoxides. The alkali metal peroxides and superoxides are powerful oxidising agents. Sodium peroxide and potassium superoxide react with carbon dioxide to form the alkali metal carbonate and oxygen gas, which allows them to be used in submarine air purifiers; the presence of water vapour, naturally present in breath, makes the removal of carbon dioxide by potassium superoxide even more efficient. All the stable alkali metals except lithium can form red ozonides (MO~3~) through low-temperature reaction of the powdered anhydrous hydroxide with ozone: the ozonides may be then extracted using liquid ammonia. They slowly decompose at standard conditions to the superoxides and oxygen, and hydrolyse immediately to the hydroxides when in contact with water. Potassium, rubidium, and caesium also form sesquioxides M~2~O~3~, which may be better considered peroxide disuperoxides, `{{chem2|[(M+)4(O2(2-))(O2-)2]}}`{=mediawiki}.
Rubidium and caesium can form a great variety of suboxides with the metals in formal oxidation states below +1. Rubidium can form Rb~6~O and Rb~9~O~2~ (copper-coloured) upon oxidation in air, while caesium forms an immense variety of oxides, such as the ozonide CsO~3~ and several brightly coloured suboxides, such as Cs~7~O (bronze), Cs~4~O (red-violet), Cs~11~O~3~ (violet), Cs~3~O (dark green), CsO, Cs~3~O~2~, as well as Cs~7~O~2~. The last of these may be heated under vacuum to generate Cs~2~O.
The alkali metals can also react analogously with the heavier chalcogens (sulfur, selenium, tellurium, and polonium), and all the alkali metal chalcogenides are known (with the exception of francium\'s). Reaction with an excess of the chalcogen can similarly result in lower chalcogenides, with chalcogen ions containing chains of the chalcogen atoms in question. For example, sodium can react with sulfur to form the sulfide (Na~2~S) and various polysulfides with the formula Na~2~S~*x*~ (*x* from 2 to 6), containing the `{{chem|S|''x''|2-}}`{=mediawiki} ions. Due to the basicity of the Se^2−^ and Te^2−^ ions, the alkali metal selenides and tellurides are alkaline in solution; when reacted directly with selenium and tellurium, alkali metal polyselenides and polytellurides are formed along with the selenides and tellurides with the `{{chem|Se|''x''|2-}}`{=mediawiki} and `{{chem|Te|''x''|2-}}`{=mediawiki} ions. They may be obtained directly from the elements in liquid ammonia or when air is not present, and are colourless, water-soluble compounds that air oxidises quickly back to selenium or tellurium. The alkali metal polonides are all ionic compounds containing the Po^2−^ ion; they are very chemically stable and can be produced by direct reaction of the elements at around 300--400 °C.
### Halides, hydrides, and pseudohalides {#halides_hydrides_and_pseudohalides}
The alkali metals are among the most electropositive elements on the periodic table and thus tend to bond ionically to the most electronegative elements on the periodic table, the halogens (fluorine, chlorine, bromine, iodine, and astatine), forming salts known as the alkali metal halides. The reaction is very vigorous and can sometimes result in explosions. All twenty stable alkali metal halides are known; the unstable ones are not known, with the exception of sodium astatide, because of the great instability and rarity of astatine and francium. The most well-known of the twenty is certainly sodium chloride, otherwise known as common salt. All of the stable alkali metal halides have the formula MX where M is an alkali metal and X is a halogen. They are all white ionic crystalline solids that have high melting points. All the alkali metal halides are soluble in water except for lithium fluoride (LiF), which is insoluble in water due to its very high lattice enthalpy. The high lattice enthalpy of lithium fluoride is due to the small sizes of the Li^+^ and F^−^ ions, causing the electrostatic interactions between them to be strong: a similar effect occurs for magnesium fluoride, consistent with the diagonal relationship between lithium and magnesium.
The alkali metals also react similarly with hydrogen to form ionic alkali metal hydrides, where the hydride anion acts as a pseudohalide: these are often used as reducing agents, producing hydrides, complex metal hydrides, or hydrogen gas. Other pseudohalides are also known, notably the cyanides. These are isostructural to the respective halides except for lithium cyanide, indicating that the cyanide ions may rotate freely. Ternary alkali metal halide oxides, such as Na~3~ClO, K~3~BrO (yellow), Na~4~Br~2~O, Na~4~I~2~O, and K~4~Br~2~O, are also known. The polyhalides are rather unstable, although those of rubidium and caesium are greatly stabilised by the feeble polarising power of these extremely large cations.
### Coordination complexes {#coordination_complexes}
Alkali metal cations do not usually form coordination complexes with simple Lewis bases due to their low charge of just +1 and their relatively large size; thus the Li^+^ ion forms most complexes and the heavier alkali metal ions form less and less (though exceptions occur for weak complexes). Lithium in particular has a very rich coordination chemistry in which it exhibits coordination numbers from 1 to 12, although octahedral hexacoordination is its preferred mode. In aqueous solution, the alkali metal ions exist as octahedral hexahydrate complexes \[M(H~2~O)~6~\]^+^, with the exception of the lithium ion, which due to its small size forms tetrahedral tetrahydrate complexes \[Li(H~2~O)~4~\]^+^; the alkali metals form these complexes because their ions are attracted by electrostatic forces of attraction to the polar water molecules. Because of this, anhydrous salts containing alkali metal cations are often used as desiccants. Alkali metals also readily form complexes with crown ethers (e.g. 12-crown-4 for Li^+^, 15-crown-5 for Na^+^, 18-crown-6 for K^+^, and 21-crown-7 for Rb^+^) and cryptands due to electrostatic attraction.
### Ammonia solutions {#ammonia_solutions}
The alkali metals dissolve slowly in liquid ammonia, forming ammoniacal solutions of solvated metal cation M^+^ and solvated electron e^−^, which react to form hydrogen gas and the alkali metal amide (MNH~2~, where M represents an alkali metal): this was first noted by Humphry Davy in 1809 and rediscovered by W. Weyl in 1864. The process may be speeded up by a catalyst. Similar solutions are formed by the heavy divalent alkaline earth metals calcium, strontium, barium, as well as the divalent lanthanides, europium and ytterbium. The amide salt is quite insoluble and readily precipitates out of solution, leaving intensely coloured ammonia solutions of the alkali metals. In 1907, Charles A. Kraus identified the colour as being due to the presence of solvated electrons, which contribute to the high electrical conductivity of these solutions. At low concentrations (below 3 M), the solution is dark blue and has ten times the conductivity of aqueous sodium chloride; at higher concentrations (above 3 M), the solution is copper-coloured and has approximately the conductivity of liquid metals like mercury. In addition to the alkali metal amide salt and solvated electrons, such ammonia solutions also contain the alkali metal cation (M^+^), the neutral alkali metal atom (M), diatomic alkali metal molecules (M~2~) and alkali metal anions (M^−^). These are unstable and eventually become the more thermodynamically stable alkali metal amide and hydrogen gas. Solvated electrons are powerful reducing agents and are often used in chemical synthesis.
### Organometallic
#### Organolithium
thumb\|upright=1.15\|Structure of the octahedral *n*-butyllithium hexamer, (C~4~H~9~Li)~6~. The aggregates are held together by delocalised covalent bonds between lithium and the terminal carbon of the butyl chain. There is no direct lithium--lithium bonding in any organolithium compound. thumb\|upright=1.15\|Solid phenyllithium forms monoclinic crystals that can be described as consisting of dimeric Li~2~(C~6~H~5~)~2~ subunits. The lithium atoms and the *ipso* carbons of the phenyl rings form a planar four-membered ring. The plane of the phenyl groups is perpendicular to the plane of this Li~2~C~2~ ring. Additional strong intermolecular bonding occurs between these phenyllithium dimers and the π electrons of the phenyl groups in the adjacent dimers, resulting in an infinite polymeric ladder structure.
Being the smallest alkali metal, lithium forms the widest variety of and most stable organometallic compounds, which are bonded covalently. Organolithium compounds are electrically non-conducting volatile solids or liquids that melt at low temperatures, and tend to form oligomers with the structure (RLi)~*x*~ where R is the organic group. As the electropositive nature of lithium puts most of the charge density of the bond on the carbon atom, effectively creating a carbanion, organolithium compounds are extremely powerful bases and nucleophiles. For use as bases, butyllithiums are often used and are commercially available. An example of an organolithium compound is methyllithium ((CH~3~Li)~*x*~), which exists in tetrameric (*x* = 4, tetrahedral) and hexameric (*x* = 6, octahedral) forms. Organolithium compounds, especially *n*-butyllithium, are useful reagents in organic synthesis, as might be expected given lithium\'s diagonal relationship with magnesium, which plays an important role in the Grignard reaction. For example, alkyllithiums and aryllithiums may be used to synthesise aldehydes and ketones by reaction with metal carbonyls. The reaction with nickel tetracarbonyl, for example, proceeds through an unstable acyl nickel carbonyl complex which then undergoes electrophilic substitution to give the desired aldehyde (using H^+^ as the electrophile) or ketone (using an alkyl halide) product.
: LiR \\ + \\ Ni(CO)4 \\ \\longrightarrow Li\^{+}\[RCONi(CO)3\]\^{-}
: Li\^{+}\[RCONi(CO)3\]\^{-}-\>\[\\ce{H\^{+}}\]\[\\ce{solvent}\] \\ Li\^{+} \\ + \\ RCHO \\ + \\ \[(solvent)Ni(CO)3\]
: Li\^{+}\[RCONi(CO)3\]\^{-}-\>\[\\ce{R\^{\'}Br}\]\[\\ce{solvent}\] \\ Li\^{+} \\ + \\ RR\^{\'}CO \\ + \\ \[(solvent)Ni(CO)3\]
Alkyllithiums and aryllithiums may also react with *N*,*N*-disubstituted amides to give aldehydes and ketones, and symmetrical ketones by reacting with carbon monoxide. They thermally decompose to eliminate a β-hydrogen, producing alkenes and lithium hydride: another route is the reaction of ethers with alkyl- and aryllithiums that act as strong bases. In non-polar solvents, aryllithiums react as the carbanions they effectively are, turning carbon dioxide to aromatic carboxylic acids (ArCO~2~H) and aryl ketones to tertiary carbinols (Ar\'~2~C(Ar)OH). Finally, they may be used to synthesise other organometallic compounds through metal-halogen exchange.
#### Heavier alkali metals {#heavier_alkali_metals}
Unlike the organolithium compounds, the organometallic compounds of the heavier alkali metals are predominantly ionic. The application of organosodium compounds in chemistry is limited in part due to competition from organolithium compounds, which are commercially available and exhibit more convenient reactivity. The principal organosodium compound of commercial importance is sodium cyclopentadienide. Sodium tetraphenylborate can also be classified as an organosodium compound since in the solid state sodium is bound to the aryl groups. Organometallic compounds of the higher alkali metals are even more reactive than organosodium compounds and of limited utility. A notable reagent is Schlosser\'s base, a mixture of *n*-butyllithium and potassium *tert*-butoxide. This reagent reacts with propene to form the compound allylpotassium (KCH~2~CHCH~2~). *cis*-2-Butene and *trans*-2-butene equilibrate when in contact with alkali metals. Whereas isomerisation is fast with lithium and sodium, it is slow with the heavier alkali metals. The heavier alkali metals also favour the sterically congested conformation. Several crystal structures of organopotassium compounds have been reported, establishing that they, like the sodium compounds, are polymeric. Organosodium, organopotassium, organorubidium and organocaesium compounds are all mostly ionic and are insoluble (or nearly so) in nonpolar solvents.
Alkyl and aryl derivatives of sodium and potassium tend to react with air. They cause the cleavage of ethers, generating alkoxides. Unlike alkyllithium compounds, alkylsodiums and alkylpotassiums cannot be made by reacting the metals with alkyl halides because Wurtz coupling occurs:
: RM + R\'X → R--R\' + MX
As such, they have to be made by reacting alkylmercury compounds with sodium or potassium metal in inert hydrocarbon solvents. While methylsodium forms tetramers like methyllithium, methylpotassium is more ionic and has the nickel arsenide structure with discrete methyl anions and potassium cations.
The alkali metals and their hydrides react with acidic hydrocarbons, for example cyclopentadienes and terminal alkynes, to give salts. Liquid ammonia, ether, or hydrocarbon solvents are used, the most common of which being tetrahydrofuran. The most important of these compounds is sodium cyclopentadienide, NaC~5~H~5~, an important precursor to many transition metal cyclopentadienyl derivatives. Similarly, the alkali metals react with cyclooctatetraene in tetrahydrofuran to give alkali metal cyclooctatetraenides; for example, dipotassium cyclooctatetraenide (K~2~C~8~H~8~) is an important precursor to many metal cyclooctatetraenyl derivatives, such as uranocene. The large and very weakly polarising alkali metal cations can stabilise large, aromatic, polarisable radical anions, such as the dark-green sodium naphthalenide, Na^+^\[C~10~H~8~•\]^−^, a strong reducing agent.
## Representative reactions of alkali metals {#representative_reactions_of_alkali_metals}
### Reaction with oxygen {#reaction_with_oxygen}
Upon reacting with oxygen, alkali metals form oxides, peroxides, superoxides and suboxides. However, the first three are more common. The table below shows the types of compounds formed in reaction with oxygen. The compound in brackets represents the minor product of combustion.
------------------ ----------- -------------- ----------------
**Alkali metal** **Oxide** **Peroxide** **Superoxide**
Li Li~2~O (Li~2~O~2~)
Na (Na~2~O) Na~2~O~2~
K KO~2~
Rb RbO~2~
Cs CsO~2~
------------------ ----------- -------------- ----------------
The alkali metal peroxides are ionic compounds that are unstable in water. The peroxide anion is weakly bound to the cation, and it is hydrolysed, forming stronger covalent bonds.
: Na~2~O~2~ + 2H~2~O → 2NaOH + H~2~O~2~
The other oxygen compounds are also unstable in water.
: 2KO~2~ + 2H~2~O → 2KOH + H~2~O~2~ + O~2~
: Li~2~O + H~2~O → 2LiOH
### Reaction with sulfur {#reaction_with_sulfur}
With sulfur, they form sulfides and polysulfides.
: 2Na + 1/8S~8~ → Na~2~S + 1/8S~8~ → Na~2~S~2~\...Na~2~S~7~
Because alkali metal sulfides are essentially salts of a weak acid and a strong base, they form basic solutions.
: S^2-^ + H~2~O → HS^−^ + HO^−^
: HS^−^ + H~2~O → H~2~S + HO^−^
### Reaction with nitrogen {#reaction_with_nitrogen}
Lithium is the only metal that combines directly with nitrogen at room temperature.
: 3Li + 1/2N~2~ → Li~3~N
Li~3~N can react with water to liberate ammonia.
: Li~3~N + 3H~2~O → 3LiOH + NH~3~
### Reaction with hydrogen {#reaction_with_hydrogen}
With hydrogen, alkali metals form saline hydrides that hydrolyse in water.
: 2 Na \\ + H2 \\ -\>\[\\ce{\\Delta}\] \\ 2 NaH
: 2 NaH \\ + \\ 2 H2O \\ \\longrightarrow \\ 2 NaOH \\ + \\ H2 \\uparrow
### Reaction with carbon {#reaction_with_carbon}
Lithium is the only metal that reacts directly with carbon to give dilithium acetylide. Na and K can react with acetylene to give acetylides.
: 2 Li \\ + \\ 2 C \\ \\longrightarrow \\ Li2C2
: 2 Na \\ + \\ 2 C2H2 \\ -\>\[\\ce{150 \\ \^{o}C}\] \\ 2 NaC2H \\ + \\ H2
: 2 Na \\ + \\ 2 NaC2H \\ -\>\[\\ce{220 \\ \^{o}C}\] \\ 2 Na2C2 \\ + \\ H2
### Reaction with water {#reaction_with_water}
On reaction with water, they generate hydroxide ions and hydrogen gas. This reaction is vigorous and highly exothermic and the hydrogen resulted may ignite in air or even explode in the case of Rb and Cs.
: Na + H~2~O → NaOH + 1/2H~2~
### Reaction with other salts {#reaction_with_other_salts}
The alkali metals are very good reducing agents. They can reduce metal cations that are less electropositive. Titanium is produced industrially by the reduction of titanium tetrachloride with Na at 400 °C (van Arkel--de Boer process).
: TiCl~4~ + 4Na → 4NaCl + Ti
### Reaction with organohalide compounds {#reaction_with_organohalide_compounds}
Alkali metals react with halogen derivatives to generate hydrocarbon via the Wurtz reaction.
: 2CH~3~-Cl + 2Na → H~3~C-CH~3~ + 2NaCl
### Alkali metals in liquid ammonia {#alkali_metals_in_liquid_ammonia}
Alkali metals dissolve in liquid ammonia or other donor solvents like aliphatic amines or hexamethylphosphoramide to give blue solutions. These solutions are believed to contain free electrons.
: Na + xNH~3~ → Na^+^ + e(NH~3~)~x~^−^
Due to the presence of solvated electrons, these solutions are very powerful reducing agents used in organic synthesis.
thumb\|upright=1.25\|centre\|Reduction reactions using sodium in liquid ammonia
Reaction 1) is known as Birch reduction. Other reductions that can be carried by these solutions are:
: S~8~ + 2e^−^ → S~8~^2-^
: Fe(CO)~5~ + 2e^−^ → Fe(CO)~4~^2-^ + CO
## Extensions
thumb\|upright=1.12\|Empirical (Na--Cs, Mg--Ra) and predicted (Fr--Uhp, Ubn--Uhh) atomic radius of the alkali and alkaline earth metals from the third to the ninth period, measured in angstroms Although francium is the heaviest alkali metal that has been discovered, there has been some theoretical work predicting the physical and chemical characteristics of hypothetical heavier alkali metals. Being the first period 8 element, the undiscovered element ununennium (element 119) is predicted to be the next alkali metal after francium and behave much like their lighter congeners; however, it is also predicted to differ from the lighter alkali metals in some properties. Its chemistry is predicted to be closer to that of potassium or rubidium instead of caesium or francium. This is unusual as periodic trends, ignoring relativistic effects would predict ununennium to be even more reactive than caesium and francium. This lowered reactivity is due to the relativistic stabilisation of ununennium\'s valence electron, increasing ununennium\'s first ionisation energy and decreasing the metallic and ionic radii; this effect is already seen for francium. This assumes that ununennium will behave chemically as an alkali metal, which, although likely, may not be true due to relativistic effects. The relativistic stabilisation of the 8s orbital also increases ununennium\'s electron affinity far beyond that of caesium and francium; indeed, ununennium is expected to have an electron affinity higher than all the alkali metals lighter than it. Relativistic effects also cause a very large drop in the polarisability of ununennium. On the other hand, ununennium is predicted to continue the trend of melting points decreasing going down the group, being expected to have a melting point between 0 °C and 30 °C.
The stabilisation of ununennium\'s valence electron and thus the contraction of the 8s orbital cause its atomic radius to be lowered to 240 pm, very close to that of rubidium (247 pm), so that the chemistry of ununennium in the +1 oxidation state should be more similar to the chemistry of rubidium than to that of francium. On the other hand, the ionic radius of the Uue^+^ ion is predicted to be larger than that of Rb^+^, because the 7p orbitals are destabilised and are thus larger than the p-orbitals of the lower shells. Ununennium may also show the +3 and +5 oxidation states, which are not seen in any other alkali metal, in addition to the +1 oxidation state that is characteristic of the other alkali metals and is also the main oxidation state of all the known alkali metals: this is because of the destabilisation and expansion of the 7p~3/2~ spinor, causing its outermost electrons to have a lower ionisation energy than what would otherwise be expected. Indeed, many ununennium compounds are expected to have a large covalent character, due to the involvement of the 7p~3/2~ electrons in the bonding.
Not as much work has been done predicting the properties of the alkali metals beyond ununennium. Although a simple extrapolation of the periodic table (by the Aufbau principle) would put element 169, unhexennium, under ununennium, Dirac-Fock calculations predict that the next element after ununennium with alkali-metal-like properties may be element 165, unhexpentium, which is predicted to have the electron configuration \[Og\] 5g^18^ 6f^14^ 7d^10^ 8s^2^ 8p~1/2~^2^ 9s^1^. This element would be intermediate in properties between an alkali metal and a group 11 element, and while its physical and atomic properties would be closer to the former, its chemistry may be closer to that of the latter. Further calculations show that unhexpentium would follow the trend of increasing ionisation energy beyond caesium, having an ionisation energy comparable to that of sodium, and that it should also continue the trend of decreasing atomic radii beyond caesium, having an atomic radius comparable to that of potassium. However, the 7d electrons of unhexpentium may also be able to participate in chemical reactions along with the 9s electron, possibly allowing oxidation states beyond +1, whence the likely transition metal behaviour of unhexpentium. Due to the alkali and alkaline earth metals both being s-block elements, these predictions for the trends and properties of ununennium and unhexpentium also mostly hold quite similarly for the corresponding alkaline earth metals unbinilium (Ubn) and unhexhexium (Uhh). Unsepttrium, element 173, may be an even better heavier homologue of ununennium; with a predicted electron configuration of \[Usb\] 6g^1^, it returns to the alkali-metal-like situation of having one easily removed electron far above a closed p-shell in energy, and is expected to be even more reactive than caesium.
The probable properties of further alkali metals beyond unsepttrium have not been explored yet as of 2019, and they may or may not be able to exist. In periods 8 and above of the periodic table, relativistic and shell-structure effects become so strong that extrapolations from lighter congeners become completely inaccurate. In addition, the relativistic and shell-structure effects (which stabilise the s-orbitals and destabilise and expand the d-, f-, and g-orbitals of higher shells) have opposite effects, causing even larger difference between relativistic and non-relativistic calculations of the properties of elements with such high atomic numbers. Interest in the chemical properties of ununennium, unhexpentium, and unsepttrium stems from the fact that they are located close to the expected locations of islands of stability, centered at elements 122 (^306^Ubb) and 164 (^482^Uhq).
## Pseudo-alkali metals {#pseudo_alkali_metals}
Many other substances are similar to the alkali metals in their tendency to form monopositive cations. Analogously to the pseudohalogens, they have sometimes been called \"pseudo-alkali metals\". These substances include some elements and many more polyatomic ions; the polyatomic ions are especially similar to the alkali metals in their large size and weak polarising power.
### Hydrogen
The element hydrogen, with one electron per neutral atom, is usually placed at the top of Group 1 of the periodic table because of its electron configuration. But hydrogen is not normally considered to be an alkali metal. Metallic hydrogen, which only exists at very high pressures, is known for its electrical and magnetic properties, not its chemical properties. Under typical conditions, pure hydrogen exists as a diatomic gas consisting of two atoms per molecule (H~2~); however, the alkali metals form diatomic molecules (such as dilithium, Li~2~) only at high temperatures, when they are in the gaseous state.
Hydrogen, like the alkali metals, has one valence electron and reacts easily with the halogens, but the similarities mostly end there because of the small size of a bare proton H^+^ compared to the alkali metal cations. Its placement above lithium is primarily due to its electron configuration. It is sometimes placed above fluorine due to their similar chemical properties, though the resemblance is likewise not absolute.
The first ionisation energy of hydrogen (1312.0 kJ/mol) is much higher than that of the alkali metals. As only one additional electron is required to fill in the outermost shell of the hydrogen atom, hydrogen often behaves like a halogen, forming the negative hydride ion, and is very occasionally considered to be a halogen on that basis. (The alkali metals can also form negative ions, known as alkalides, but these are little more than laboratory curiosities, being unstable.) An argument against this placement is that formation of hydride from hydrogen is endothermic, unlike the exothermic formation of halides from halogens. The radius of the H^−^ anion also does not fit the trend of increasing size going down the halogens: indeed, H^−^ is very diffuse because its single proton cannot easily control both electrons. It was expected for some time that liquid hydrogen would show metallic properties; while this has been shown to not be the case, under extremely high pressures, such as those found at the cores of Jupiter and Saturn, hydrogen does become metallic and behaves like an alkali metal; in this phase, it is known as metallic hydrogen. The electrical resistivity of liquid metallic hydrogen at 3000 K is approximately equal to that of liquid rubidium and caesium at 2000 K at the respective pressures when they undergo a nonmetal-to-metal transition.
The 1s^1^ electron configuration of hydrogen, while analogous to that of the alkali metals (ns^1^), is unique because there is no 1p subshell. Hence it can lose an electron to form the hydron H^+^, or gain one to form the hydride ion H^−^. In the former case it resembles superficially the alkali metals; in the latter case, the halogens, but the differences due to the lack of a 1p subshell are important enough that neither group fits the properties of hydrogen well. Group 14 is also a good fit in terms of thermodynamic properties such as ionisation energy and electron affinity, but hydrogen cannot be tetravalent. Thus none of the three placements are entirely satisfactory, although group 1 is the most common placement (if one is chosen) because of the electron configuration and the fact that the hydron is by far the most important of all monatomic hydrogen species, being the foundation of acid-base chemistry. As an example of hydrogen\'s unorthodox properties stemming from its unusual electron configuration and small size, the hydrogen ion is very small (radius around 150 fm compared to the 50--220 pm size of most other atoms and ions) and so is nonexistent in condensed systems other than in association with other atoms or molecules. Indeed, transferring of protons between chemicals is the basis of acid-base chemistry. Also unique is hydrogen\'s ability to form hydrogen bonds, which are an effect of charge-transfer, electrostatic, and electron correlative contributing phenomena. While analogous lithium bonds are also known, they are mostly electrostatic. Nevertheless, hydrogen can take on the same structural role as the alkali metals in some molecular crystals, and has a close relationship with the lightest alkali metals (especially lithium).
### Ammonium and derivatives {#ammonium_and_derivatives}
The ammonium ion (`{{chem2|NH4+}}`{=mediawiki}) has very similar properties to the heavier alkali metals, acting as an alkali metal intermediate between potassium and rubidium, and is often considered a close relative. For example, most alkali metal salts are soluble in water, a property which ammonium salts share. Ammonium is expected to behave stably as a metal (`{{chem2|NH4+}}`{=mediawiki} ions in a sea of delocalised electrons) at very high pressures (though less than the typical pressure where transitions from insulating to metallic behaviour occur around, 100 GPa), and could possibly occur inside the ice giants Uranus and Neptune, which may have significant impacts on their interior magnetic fields. It has been estimated that the transition from a mixture of ammonia and dihydrogen molecules to metallic ammonium may occur at pressures just below 25 GPa. Under standard conditions, ammonium can form a metallic amalgam with mercury.
Other \"pseudo-alkali metals\" include the alkylammonium cations, in which some of the hydrogen atoms in the ammonium cation are replaced by alkyl or aryl groups. In particular, the quaternary ammonium cations (`{{chem2|NR4+}}`{=mediawiki}) are very useful since they are permanently charged, and they are often used as an alternative to the expensive Cs^+^ to stabilise very large and very easily polarisable anions such as `{{chem2|HI2-}}`{=mediawiki}. Tetraalkylammonium hydroxides, like alkali metal hydroxides, are very strong bases that react with atmospheric carbon dioxide to form carbonates. Furthermore, the nitrogen atom may be replaced by a phosphorus, arsenic, or antimony atom (the heavier nonmetallic pnictogens), creating a phosphonium (`{{chem2|PH4+}}`{=mediawiki}) or arsonium (`{{chem2|AsH4+}}`{=mediawiki}) cation that can itself be substituted similarly; while stibonium (`{{chem2|SbH4+}}`{=mediawiki}) itself is not known, some of its organic derivatives are characterised.
### Cobaltocene and derivatives {#cobaltocene_and_derivatives}
Cobaltocene, Co(C~5~H~5~)~2~, is a metallocene, the cobalt analogue of ferrocene. It is a dark purple solid. Cobaltocene has 19 valence electrons, one more than usually found in organotransition metal complexes, such as its very stable relative, ferrocene, in accordance with the 18-electron rule. This additional electron occupies an orbital that is antibonding with respect to the Co--C bonds. Consequently, many chemical reactions of Co(C~5~H~5~)~2~ are characterized by its tendency to lose this \"extra\" electron, yielding a very stable 18-electron cation known as cobaltocenium. Many cobaltocenium salts coprecipitate with caesium salts, and cobaltocenium hydroxide is a strong base that absorbs atmospheric carbon dioxide to form cobaltocenium carbonate. Like the alkali metals, cobaltocene is a strong reducing agent, and decamethylcobaltocene is stronger still due to the combined inductive effect of the ten methyl groups. Cobalt may be substituted by its heavier congener rhodium to give rhodocene, an even stronger reducing agent. Iridocene (involving iridium) would presumably be still more potent, but is not very well-studied due to its instability.
### Thallium
Thallium is the heaviest stable element in group 13 of the periodic table. At the bottom of the periodic table, the inert-pair effect is quite strong, because of the relativistic stabilisation of the 6s orbital and the decreasing bond energy as the atoms increase in size so that the amount of energy released in forming two more bonds is not worth the high ionisation energies of the 6s electrons. It displays the +1 oxidation state that all the known alkali metals display, and thallium compounds with thallium in its +1 oxidation state closely resemble the corresponding potassium or silver compounds stoichiometrically due to the similar ionic radii of the Tl^+^ (164 pm), K^+^ (152 pm) and Ag^+^ (129 pm) ions. It was sometimes considered an alkali metal in continental Europe (but not in England) in the years immediately following its discovery, and was placed just after caesium as the sixth alkali metal in Dmitri Mendeleev\'s 1869 periodic table and Julius Lothar Meyer\'s 1868 periodic table. Mendeleev\'s 1871 periodic table and Meyer\'s 1870 periodic table put thallium in its current position in the boron group and left the space below caesium blank. However, thallium also displays the oxidation state +3, which no known alkali metal displays (although ununennium, the undiscovered seventh alkali metal, is predicted to possibly display the +3 oxidation state). The sixth alkali metal is now considered to be francium. While Tl^+^ is stabilised by the inert-pair effect, this inert pair of 6s electrons is still able to participate chemically, so that these electrons are stereochemically active in aqueous solution. Additionally, the thallium halides (except TlF) are quite insoluble in water, and TlI has an unusual structure because of the presence of the stereochemically active inert pair in thallium.
### Copper, silver, and gold {#copper_silver_and_gold}
The group 11 metals (or coinage metals), copper, silver, and gold, are typically categorised as transition metals given they can form ions with incomplete d-shells. Physically, they have the relatively low melting points and high electronegativity values associated with post-transition metals. \"The filled *d* subshell and free *s* electron of Cu, Ag, and Au contribute to their high electrical and thermal conductivity. Transition metals to the left of group 11 experience interactions between *s* electrons and the partially filled *d* subshell that lower electron mobility.\" Chemically, the group 11 metals behave like main-group metals in their +1 valence states, and are hence somewhat related to the alkali metals: this is one reason for their previously being labelled as \"group IB\", paralleling the alkali metals\' \"group IA\". They are occasionally classified as post-transition metals. Their spectra are analogous to those of the alkali metals. Their monopositive ions are paramagnetic and contribute no colour to their salts, like those of the alkali metals.
In Mendeleev\'s 1871 periodic table, copper, silver, and gold are listed twice, once under group VIII (with the iron triad and platinum group metals), and once under group IB. Group IB was nonetheless parenthesised to note that it was tentative. Mendeleev\'s main criterion for group assignment was the maximum oxidation state of an element: on that basis, the group 11 elements could not be classified in group IB, due to the existence of copper(II) and gold(III) compounds being known at that time. However, eliminating group IB would make group I the only main group (group VIII was labelled a transition group) to lack an A--B bifurcation. Soon afterward, a majority of chemists chose to classify these elements in group IB and remove them from group VIII for the resulting symmetry: this was the predominant classification until the rise of the modern medium-long 18-column periodic table, which separated the alkali metals and group 11 metals.
The coinage metals were traditionally regarded as a subdivision of the alkali metal group, due to them sharing the characteristic s^1^ electron configuration of the alkali metals (group 1: p^6^s^1^; group 11: d^10^s^1^). However, the similarities are largely confined to the stoichiometries of the +1 compounds of both groups, and not their chemical properties. This stems from the filled d subshell providing a much weaker shielding effect on the outermost s electron than the filled p subshell, so that the coinage metals have much higher first ionisation energies and smaller ionic radii than do the corresponding alkali metals. Furthermore, they have higher melting points, hardnesses, and densities, and lower reactivities and solubilities in liquid ammonia, as well as having more covalent character in their compounds. Finally, the alkali metals are at the top of the electrochemical series, whereas the coinage metals are almost at the very bottom. The coinage metals\' filled d shell is much more easily disrupted than the alkali metals\' filled p shell, so that the second and third ionisation energies are lower, enabling higher oxidation states than +1 and a richer coordination chemistry, thus giving the group 11 metals clear transition metal character. Particularly noteworthy is gold forming ionic compounds with rubidium and caesium, in which it forms the auride ion (Au^−^) which also occurs in solvated form in liquid ammonia solution: here gold behaves as a pseudohalogen because its 5d^10^6s^1^ configuration has one electron less than the quasi-closed shell 5d^10^6s^2^ configuration of mercury.
## Production and isolation {#production_and_isolation}
The production of pure alkali metals is somewhat complicated due to their extreme reactivity with commonly used substances, such as water. From their silicate ores, all the stable alkali metals may be obtained the same way: sulfuric acid is first used to dissolve the desired alkali metal ion and aluminium(III) ions from the ore (leaching), whereupon basic precipitation removes aluminium ions from the mixture by precipitating it as the hydroxide. The remaining insoluble alkali metal carbonate is then precipitated selectively; the salt is then dissolved in hydrochloric acid to produce the chloride. The result is then left to evaporate and the alkali metal can then be isolated. Lithium and sodium are typically isolated through electrolysis from their liquid chlorides, with calcium chloride typically added to lower the melting point of the mixture. The heavier alkali metals, however, are more typically isolated in a different way, where a reducing agent (typically sodium for potassium and magnesium or calcium for the heaviest alkali metals) is used to reduce the alkali metal chloride. The liquid or gaseous product (the alkali metal) then undergoes fractional distillation for purification. Most routes to the pure alkali metals require the use of electrolysis due to their high reactivity; one of the few which does not is the pyrolysis of the corresponding alkali metal azide, which yields the metal for sodium, potassium, rubidium, and caesium and the nitride for lithium.
Lithium salts have to be extracted from the water of mineral springs, brine pools, and brine deposits. The metal is produced electrolytically from a mixture of fused lithium chloride and potassium chloride.
Sodium occurs mostly in seawater and dried seabed, but is now produced through electrolysis of sodium chloride by lowering the melting point of the substance to below 700 °C through the use of a Downs cell. Extremely pure sodium can be produced through the thermal decomposition of sodium azide. Potassium occurs in many minerals, such as sylvite (potassium chloride). Previously, potassium was generally made from the electrolysis of potassium chloride or potassium hydroxide, found extensively in places such as Canada, Russia, Belarus, Germany, Israel, United States, and Jordan, in a method similar to how sodium was produced in the late 1800s and early 1900s. It can also be produced from seawater. However, these methods are problematic because the potassium metal tends to dissolve in its molten chloride and vaporises significantly at the operating temperatures, potentially forming the explosive superoxide. As a result, pure potassium metal is now produced by reducing molten potassium chloride with sodium metal at 850 °C.
: Na (g) + KCl (l) `{{eqm}}`{=mediawiki} NaCl (l) + K (g)
Although sodium is less reactive than potassium, this process works because at such high temperatures potassium is more volatile than sodium and can easily be distilled off, so that the equilibrium shifts towards the right to produce more potassium gas and proceeds almost to completion.
Metals like sodium are obtained by electrolysis of molten salts. Rb & Cs obtained mainly as by products of Li processing. To make pure caesium, ores of caesium and rubidium are crushed and heated to 650 °C with sodium metal, generating an alloy that can then be separated via a fractional distillation technique. Because metallic caesium is too reactive to handle, it is normally offered as caesium azide (CsN3). Caesium hydroxide is formed when caesium interacts aggressively with water and ice (CsOH).
Rubidium is the 16th most abundant element in the earth\'s crust; however, it is quite rare. Some minerals found in North America, South Africa, Russia, and Canada contain rubidium. Some potassium minerals (lepidolites, biotites, feldspar, carnallite) contain it, together with caesium. Pollucite, carnallite, leucite, and lepidolite are all minerals that contain rubidium. As a by-product of lithium extraction, it is commercially obtained from lepidolite. Rubidium is also found in potassium rocks and brines, which is a commercial supply. The majority of rubidium is now obtained as a byproduct of refining lithium. Rubidium is used in vacuum tubes as a getter, a material that combines with and removes trace gases from vacuum tubes. For several years in the 1950s and 1960s, a by-product of the potassium production called Alkarb was a main source for rubidium. Alkarb contained 21% rubidium while the rest was potassium and a small fraction of caesium. Today the largest producers of caesium, for example the Tanco Mine in Manitoba, Canada, produce rubidium as by-product from pollucite. Today, a common method for separating rubidium from potassium and caesium is the fractional crystallisation of a rubidium and caesium alum (Cs, Rb)Al(SO~4~)~2~·12H~2~O, which yields pure rubidium alum after approximately 30 recrystallisations. The limited applications and the lack of a mineral rich in rubidium limit the production of rubidium compounds to 2 to 4 tonnes per year. Caesium, however, is not produced from the above reaction. Instead, the mining of pollucite ore is the main method of obtaining pure caesium, extracted from the ore mainly by three methods: acid digestion, alkaline decomposition, and direct reduction. Both metals are produced as by-products of lithium production: after 1958, when interest in lithium\'s thermonuclear properties increased sharply, the production of rubidium and caesium also increased correspondingly. Pure rubidium and caesium metals are produced by reducing their chlorides with calcium metal at 750 °C and low pressure.
As a result of its extreme rarity in nature, most francium is synthesised in the nuclear reaction ^197^Au + ^18^O → ^210^Fr + 5 n, yielding francium-209, francium-210, and francium-211. The greatest quantity of francium ever assembled to date is about 300,000 neutral atoms, which were synthesised using the nuclear reaction given above. When the only natural isotope francium-223 is specifically required, it is produced as the alpha daughter of actinium-227, itself produced synthetically from the neutron irradiation of natural radium-226, one of the daughters of natural uranium-238.
## Applications
Lithium, sodium, and potassium have many useful applications, while rubidium and caesium are very notable in academic contexts but do not have many applications yet. Lithium is the key ingredient for a range of lithium-based batteries, and lithium oxide can help process silica. Lithium stearate is a thickener and can be used to make lubricating greases; it is produced from lithium hydroxide, which is also used to absorb carbon dioxide in space capsules and submarines. Lithium chloride is used as a brazing alloy for aluminium parts. In medicine, some lithium salts are used as mood-stabilising pharmaceuticals. Metallic lithium is used in alloys with magnesium and aluminium to give very tough and light alloys.
Sodium compounds have many applications, the most well-known being sodium chloride as table salt. Sodium salts of fatty acids are used as soap. Pure sodium metal also has many applications, including use in sodium-vapour lamps, which produce very efficient light compared to other types of lighting, and can help smooth the surface of other metals. Being a strong reducing agent, it is often used to reduce many other metals, such as titanium and zirconium, from their chlorides. Furthermore, it is very useful as a heat-exchange liquid in fast breeder nuclear reactors due to its low melting point, viscosity, and cross-section towards neutron absorption. Sodium-ion batteries may provide cheaper alternatives to their equivalent lithium-based cells. Both sodium and potassium are commonly used as GRAS counterions to create more water-soluble and hence more bioavailable salt forms of acidic pharmaceuticals.
Potassium compounds are often used as fertilisers as potassium is an important element for plant nutrition. Potassium hydroxide is a very strong base, and is used to control the pH of various substances. Potassium nitrate and potassium permanganate are often used as powerful oxidising agents. Potassium superoxide is used in breathing masks, as it reacts with carbon dioxide to give potassium carbonate and oxygen gas. Pure potassium metal is not often used, but its alloys with sodium may substitute for pure sodium in fast breeder nuclear reactors.
Rubidium and caesium are often used in atomic clocks. Caesium atomic clocks are extraordinarily accurate; if a clock had been made at the time of the dinosaurs, it would be off by less than four seconds (after 80 million years). For that reason, caesium atoms are used as the definition of the second. Rubidium ions are often used in purple fireworks, and caesium is often used in drilling fluids in the petroleum industry.
Francium has no commercial applications, but because of francium\'s relatively simple atomic structure, among other things, it has been used in spectroscopy experiments, leading to more information regarding energy levels and the coupling constants of the weak interaction. Studies on the light emitted by laser-trapped francium-210 ions have provided accurate data on transitions between atomic energy levels, similar to those predicted by quantum theory.
## Biological role and precautions {#biological_role_and_precautions}
### Metals
Pure alkali metals are dangerously reactive with air and water and must be kept away from heat, fire, oxidising agents, acids, most organic compounds, halocarbons, plastics, and moisture. They also react with carbon dioxide and carbon tetrachloride, so that normal fire extinguishers are counterproductive when used on alkali metal fires. Some Class D dry powder extinguishers designed for metal fires are effective, depriving the fire of oxygen and cooling the alkali metal.
Experiments are usually conducted using only small quantities of a few grams in a fume hood. Small quantities of lithium may be disposed of by reaction with cool water, but the heavier alkali metals should be dissolved in the less reactive isopropanol. The alkali metals must be stored under mineral oil or an inert atmosphere. The inert atmosphere used may be argon or nitrogen gas, except for lithium, which reacts with nitrogen. Rubidium and caesium must be kept away from air, even under oil, because even a small amount of air diffused into the oil may trigger formation of the dangerously explosive peroxide; for the same reason, potassium should not be stored under oil in an oxygen-containing atmosphere for longer than 6 months.
### Ions
The bioinorganic chemistry of the alkali metal ions has been extensively reviewed. Solid state crystal structures have been determined for many complexes of alkali metal ions in small peptides, nucleic acid constituents, carbohydrates and ionophore complexes.
Lithium naturally only occurs in traces in biological systems and has no known biological role, but does have effects on the body when ingested. Lithium carbonate is used as a mood stabiliser in psychiatry to treat bipolar disorder (manic-depression) in daily doses of about 0.5 to 2 grams, although there are side-effects. Excessive ingestion of lithium causes drowsiness, slurred speech and vomiting, among other symptoms, and poisons the central nervous system, which is dangerous as the required dosage of lithium to treat bipolar disorder is only slightly lower than the toxic dosage. Its biochemistry, the way it is handled by the human body and studies using rats and goats suggest that it is an essential trace element, although the natural biological function of lithium in humans has yet to be identified.
Sodium and potassium occur in all known biological systems, generally functioning as electrolytes inside and outside cells. Sodium is an essential nutrient that regulates blood volume, blood pressure, osmotic equilibrium and pH; the minimum physiological requirement for sodium is 500 milligrams per day. Sodium chloride (also known as common salt) is the principal source of sodium in the diet, and is used as seasoning and preservative, such as for pickling and jerky; most of it comes from processed foods. The Dietary Reference Intake for sodium is 1.5 grams per day, but most people in the United States consume more than 2.3 grams per day, the minimum amount that promotes hypertension; this in turn causes 7.6 million premature deaths worldwide.
Potassium is the major cation (positive ion) inside animal cells, while sodium is the major cation outside animal cells. The concentration differences of these charged particles causes a difference in electric potential between the inside and outside of cells, known as the membrane potential. The balance between potassium and sodium is maintained by ion transporter proteins in the cell membrane. The cell membrane potential created by potassium and sodium ions allows the cell to generate an action potential---a \"spike\" of electrical discharge. The ability of cells to produce electrical discharge is critical for body functions such as neurotransmission, muscle contraction, and heart function. Disruption of this balance may thus be fatal: for example, ingestion of large amounts of potassium compounds can lead to hyperkalemia strongly influencing the cardiovascular system. Potassium chloride is used in the United States for lethal injection executions.
Due to their similar atomic radii, rubidium and caesium in the body mimic potassium and are taken up similarly. Rubidium has no known biological role, but may help stimulate metabolism, and, similarly to caesium, replace potassium in the body causing potassium deficiency. Partial substitution is quite possible and rather non-toxic: a 70 kg person contains on average 0.36 g of rubidium, and an increase in this value by 50 to 100 times did not show negative effects in test persons. Rats can survive up to 50% substitution of potassium by rubidium. Rubidium (and to a much lesser extent caesium) can function as temporary cures for hypokalemia; while rubidium can adequately physiologically substitute potassium in some systems, caesium is never able to do so. There is only very limited evidence in the form of deficiency symptoms for rubidium being possibly essential in goats; even if this is true, the trace amounts usually present in food are more than enough.
Caesium compounds are rarely encountered by most people, but most caesium compounds are mildly toxic. Like rubidium, caesium tends to substitute potassium in the body, but is significantly larger and is therefore a poorer substitute. Excess caesium can lead to hypokalemia, arrhythmia, and acute cardiac arrest, but such amounts would not ordinarily be encountered in natural sources. As such, caesium is not a major chemical environmental pollutant. The median lethal dose (LD~50~) value for caesium chloride in mice is 2.3 g per kilogram, which is comparable to the LD~50~ values of potassium chloride and sodium chloride. Caesium chloride has been promoted as an alternative cancer therapy, but has been linked to the deaths of over 50 patients, on whom it was used as part of a scientifically unvalidated cancer treatment.
Radioisotopes of caesium require special precautions: the improper handling of caesium-137 gamma ray sources can lead to release of this radioisotope and radiation injuries. Perhaps the best-known case is the Goiânia accident of 1987, in which an improperly-disposed-of radiation therapy system from an abandoned clinic in the city of Goiânia, Brazil, was scavenged from a junkyard, and the glowing caesium salt sold to curious, uneducated buyers. This led to four deaths and serious injuries from radiation exposure. Together with caesium-134, iodine-131, and strontium-90, caesium-137 was among the isotopes distributed by the Chernobyl disaster which constitute the greatest risk to health. Radioisotopes of francium would presumably be dangerous as well due to their high decay energy and short half-life, but none have been produced in large enough amounts to pose any serious risk.
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Atomic number
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The **atomic number** or **nuclear charge number** (symbol ***Z***) of a chemical element is the charge number of its atomic nucleus. For ordinary nuclei composed of protons and neutrons, this is equal to the **proton number** (***n*~p~**) or the number of protons found in the nucleus of every atom of that element. The atomic number can be used to uniquely identify ordinary chemical elements. In an ordinary uncharged atom, the atomic number is also equal to the number of electrons.
For an ordinary atom which contains protons, neutrons and electrons, the sum of the atomic number *Z* and the neutron number *N* gives the atom\'s atomic mass number *A*. Since protons and neutrons have approximately the same mass (and the mass of the electrons is negligible for many purposes) and the mass defect of the nucleon binding is always small compared to the nucleon mass, the atomic mass of any atom, when expressed in daltons (making a quantity called the \"relative isotopic mass\"), is within 1% of the whole number *A*.
Atoms with the same atomic number but different neutron numbers, and hence different mass numbers, are known as isotopes. A little more than three-quarters of naturally occurring elements exist as a mixture of isotopes (see monoisotopic elements), and the average isotopic mass of an isotopic mixture for an element (called the relative atomic mass) in a defined environment on Earth determines the element\'s standard atomic weight. Historically, it was these atomic weights of elements (in comparison to hydrogen) that were the quantities measurable by chemists in the 19th century.
The conventional symbol *Z* comes from the German word *Zahl* \'number\', which, before the modern synthesis of ideas from chemistry and physics, merely denoted an element\'s numerical place in the periodic table, whose order was then approximately, but not completely, consistent with the order of the elements by atomic weights. Only after 1915, with the suggestion and evidence that this *Z* number was also the nuclear charge and a physical characteristic of atoms, did the word *Atomzahl* (and its English equivalent *atomic number*) come into common use in this context.
The rules above do not always apply to exotic atoms which contain short-lived elementary particles other than protons, neutrons and electrons.
## Notation
The atomic number is used in AZE notation, (with *A* as the mass number, *Z* the atomic number, and E for element) to denote an isotope. When a chemical symbol is used, e.g. \"C\" for carbon, standard notation uses a superscript at the upper left of the chemical symbol for the mass number and indicates the atomic number with a subscript at the lower left (e.g. `{{nuclide|He|3}}`{=mediawiki}, `{{nuclide|He|4}}`{=mediawiki}, `{{nuclide|C|12}}`{=mediawiki}, `{{nuclide|C|14}}`{=mediawiki}, `{{nuclide|U|235}}`{=mediawiki}, and `{{nuclide|U|239}}`{=mediawiki}). Because the atomic number is given by the element symbol, it is common to state only the mass number in the superscript and leave out the atomic number subscript (e.g. `{{SimpleNuclide|He|3}}`{=mediawiki}, `{{SimpleNuclide|He|4}}`{=mediawiki}, `{{SimpleNuclide|C|12}}`{=mediawiki}, `{{SimpleNuclide|C|14}}`{=mediawiki}, `{{SimpleNuclide|U|235}}`{=mediawiki}, and `{{SimpleNuclide|U|239}}`{=mediawiki}).
The common pronunciation of the AZE notation is different from how it is written: `{{nuclide|He|4}}`{=mediawiki} is commonly pronounced as helium-four instead of four-two-helium, and `{{nuclide|U|235}}`{=mediawiki} as uranium two-thirty-five (American English) or uranium-two-three-five (British) instead of 235-92-uranium. Various notations appear in older sources were used, such as Ne(22) in 1934, Ne^22^ for neon-22 (1935) or Pb~210~ for lead-210 (1933)
## History
In the 19th century, the term \"atomic number\" typically meant the number of atoms in a given volume. Modern chemists prefer to use the concept of molar concentration.
In 1913, Antonius van den Broek proposed that the electric charge of an atomic nucleus, expressed as a multiplier of the elementary charge, was equal to the element\'s sequential position on the periodic table. Ernest Rutherford, in various articles in which he discussed van den Broek\'s idea, used the term \"atomic number\" to refer to an element\'s position on the periodic table. No writer before Rutherford is known to have used the term \"atomic number\" in this way, so it was probably he who established this definition.
After Rutherford deduced the existence of the proton in 1920, \"atomic number\" customarily referred to the proton number of an atom. In 1921, the German Atomic Weight Commission based its new periodic table on the nuclear charge number and in 1923 the International Committee on Chemical Elements followed suit.
### The periodic table and a natural number for each element {#the_periodic_table_and_a_natural_number_for_each_element}
The periodic table of elements creates an ordering of the elements, and so they can be numbered in order. Dmitri Mendeleev arranged his first periodic tables (first published on March 6, 1869) in order of atomic weight (\"Atomgewicht\"). However, in consideration of the elements\' observed chemical properties, he changed the order slightly and placed tellurium (atomic weight 127.6) ahead of iodine (atomic weight 126.9). This placement is consistent with the modern practice of ordering the elements by proton number, *Z*, but that number was not known or suspected at the time.
A simple numbering based on atomic weight position was never entirely satisfactory. In addition to the case of iodine and tellurium, several other pairs of elements (such as argon and potassium, cobalt and nickel) were later shown to have nearly identical or reversed atomic weights, thus requiring their placement in the periodic table to be determined by their chemical properties. However the gradual identification of more and more chemically similar lanthanide elements, whose atomic number was not obvious, led to inconsistency and uncertainty in the periodic numbering of elements at least from lutetium (element 71) onward (hafnium was not known at this time).
### The Rutherford-Bohr model and van den Broek {#the_rutherford_bohr_model_and_van_den_broek}
In 1911, Ernest Rutherford gave a model of the atom in which a central nucleus held most of the atom\'s mass and a positive charge which, in units of the electron\'s charge, was to be approximately equal to half of the atom\'s atomic weight, expressed in numbers of hydrogen atoms. This central charge would thus be approximately half the atomic weight (though it was almost 25% different from the atomic number of gold `{{nowrap|1=(''Z'' = 79}}`{=mediawiki}, `{{nowrap|1=''A'' = 197}}`{=mediawiki}), the single element from which Rutherford made his guess). Nevertheless, in spite of Rutherford\'s estimation that gold had a central charge of about 100 (but was element `{{nowrap|1=''Z'' = 79}}`{=mediawiki} on the periodic table), a month after Rutherford\'s paper appeared, Antonius van den Broek first formally suggested that the central charge and number of electrons in an atom were *exactly* equal to its place in the periodic table (also known as element number, atomic number, and symbolized *Z*). This eventually proved to be the case.
### Moseley\'s 1913 experiment {#moseleys_1913_experiment}
The experimental position improved dramatically after research by Henry Moseley in 1913. Moseley, after discussions with Bohr who was at the same lab (and who had used Van den Broek\'s hypothesis in his Bohr model of the atom), decided to test Van den Broek\'s and Bohr\'s hypothesis directly, by seeing if spectral lines emitted from excited atoms fitted the Bohr theory\'s postulation that the frequency of the spectral lines be proportional to the square of *Z*.
To do this, Moseley measured the wavelengths of the innermost photon transitions (K and L lines) produced by the elements from aluminium (*Z* = 13) to gold (*Z* = 79) used as a series of movable anodic targets inside an x-ray tube. The square root of the frequency of these photons `{{nowrap|(x-rays)}}`{=mediawiki} increased from one target to the next in an arithmetic progression. This led to the conclusion (Moseley\'s law) that the atomic number does closely correspond (with an offset of one unit for K-lines, in Moseley\'s work) to the calculated electric charge of the nucleus, i.e. the element number *Z*. Among other things, Moseley demonstrated that the lanthanide series (from lanthanum to lutetium inclusive) must have 15 members---no fewer and no more---which was far from obvious from known chemistry at that time.
### Missing elements {#missing_elements}
After Moseley\'s death in 1915, the atomic numbers of all known elements from hydrogen to uranium (*Z* = 92) were examined by his method. There were seven elements (with *Z* \< 92) which were not found and therefore identified as still undiscovered, corresponding to atomic numbers 43, 61, 72, 75, 85, 87 and 91. From 1918 to 1947, all seven of these missing elements were discovered. By this time, the first four transuranium elements had also been discovered, so that the periodic table was complete with no gaps as far as curium (*Z* = 96).
### The proton and the idea of nuclear electrons {#the_proton_and_the_idea_of_nuclear_electrons}
In 1915, the reason for nuclear charge being quantized in units of *Z*, which were now recognized to be the same as the element number, was not understood. An old idea called Prout\'s hypothesis had postulated that the elements were all made of residues (or \"protyles\") of the lightest element hydrogen, which in the Bohr-Rutherford model had a single electron and a nuclear charge of one. However, as early as 1907, Rutherford and Thomas Royds had shown that alpha particles, which had a charge of +2, were the nuclei of helium atoms, which had a mass four times that of hydrogen, not two times. If Prout\'s hypothesis were true, something had to be neutralizing some of the charge of the hydrogen nuclei present in the nuclei of heavier atoms.
In 1917, Rutherford succeeded in generating hydrogen nuclei from a nuclear reaction between alpha particles and nitrogen gas, and believed he had proven Prout\'s law. He called the new heavy nuclear particles protons in 1920 (alternate names being proutons and protyles). It had been immediately apparent from the work of Moseley that the nuclei of heavy atoms have more than twice as much mass as would be expected from their being made of hydrogen nuclei, and thus there was required a hypothesis for the neutralization of the extra protons presumed present in all heavy nuclei. A helium nucleus was presumed to have four protons plus two \"nuclear electrons\" (electrons bound inside the nucleus) to cancel two charges. At the other end of the periodic table, a nucleus of gold with a mass 197 times that of hydrogen was thought to contain 118 nuclear electrons in the nucleus to give it a residual charge of +79, consistent with its atomic number.
### Discovery of the neutron makes *Z* the proton number {#discovery_of_the_neutron_makes_z_the_proton_number}
All consideration of nuclear electrons ended with James Chadwick\'s discovery of the neutron in 1932. An atom of gold now was seen as containing 118 neutrons rather than 118 nuclear electrons, and its positive nuclear charge now was realized to come entirely from a content of 79 protons. Since Moseley had previously shown that the atomic number *Z* of an element equals this positive charge, it was now clear that *Z* is identical to the number of protons of its nuclei.
## Chemical properties {#chemical_properties}
Each element has a specific set of chemical properties as a consequence of the number of electrons present in the neutral atom, which is *Z* (the atomic number). The configuration of these electrons follows from the principles of quantum mechanics. The number of electrons in each element\'s electron shells, particularly the outermost valence shell, is the primary factor in determining its chemical bonding behavior. Hence, it is the atomic number alone that determines the chemical properties of an element; and it is for this reason that an element can be defined as consisting of *any* mixture of atoms with a given atomic number.
## New elements {#new_elements}
The quest for new elements is usually described using atomic numbers. As of `{{year}}`{=mediawiki}, all elements with atomic numbers 1 to 118 have been observed. The most recent element discovered was number 117 (tennessine) in 2009. Synthesis of new elements is accomplished by bombarding target atoms of heavy elements with ions, such that the sum of the atomic numbers of the target and ion elements equals the atomic number of the element being created. In general, the half-life of a nuclide becomes shorter as atomic number increases, though undiscovered nuclides with certain \"magic\" numbers of protons and neutrons may have relatively longer half-lives and comprise an island of stability.
A hypothetical element composed only of neutrons, neutronium, has also been proposed and would have atomic number 0, but has never been observed.
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Anatomy
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*Volume 5: Anatomic*}} `{{for-multi|the anatomy of plants|Plant anatomy|other uses}}`{=mediawiki} `{{good article}}`{=mediawiki} `{{Use dmy dates|date=July 2022}}`{=mediawiki} `{{Use Oxford spelling|date=September 2016}}`{=mediawiki} `{{TopicTOC-Biology}}`{=mediawiki} **Anatomy** (`{{etymology|grc|''{{wikt-lang|grc|ἀνατομή}}'' ({{grc-transl|ἀνατομή}})|[[dissection]]}}`{=mediawiki}) is the branch of morphology concerned with the study of the internal structure of organisms and their parts. Anatomy is a branch of natural science that deals with the structural organization of living things. It is an old science, having its beginnings in prehistoric times. Anatomy is inherently tied to developmental biology, embryology, comparative anatomy, evolutionary biology, and phylogeny, as these are the processes by which anatomy is generated, both over immediate and long-term timescales. Anatomy and physiology, which study the structure and function of organisms and their parts respectively, make a natural pair of related disciplines, and are often studied together. Human anatomy is one of the essential basic sciences that are applied in medicine, and is often studied alongside physiology.
Anatomy is a complex and dynamic field that is constantly evolving as discoveries are made. In recent years, there has been a significant increase in the use of advanced imaging techniques, such as MRI and CT scans, which allow for more detailed and accurate visualizations of the body\'s structures.
The discipline of anatomy is divided into macroscopic and microscopic parts. Macroscopic anatomy, or gross anatomy, is the examination of an animal\'s body parts using unaided eyesight. Gross anatomy also includes the branch of superficial anatomy. Microscopic anatomy involves the use of optical instruments in the study of the tissues of various structures, known as histology, and also in the study of cells.
The history of anatomy is characterized by a progressive understanding of the functions of the organs and structures of the human body. Methods have also improved dramatically, advancing from the examination of animals by dissection of carcasses and cadavers (corpses) to 20th-century medical imaging techniques, including X-ray, ultrasound, and magnetic resonance imaging.
## Etymology and definition {#etymology_and_definition}
Derived from the Greek *ἀνατομή* *anatomē* \"dissection\" (from *ἀνατέμνω* *anatémnō* \"I cut up, cut open\" from ἀνά *aná* \"up\", and τέμνω *témnō* \"I cut\"), anatomy is the scientific study of the structure of organisms including their systems, organs and tissues. It includes the appearance and position of the various parts, the materials from which they are composed, and their relationships with other parts. Anatomy is quite distinct from physiology and biochemistry, which deal respectively with the functions of those parts and the chemical processes involved. For example, an anatomist is concerned with the shape, size, position, structure, blood supply and innervation of an organ such as the liver; while a physiologist is interested in the production of bile, the role of the liver in nutrition and the regulation of bodily functions.
The discipline of anatomy can be subdivided into a number of branches, including gross or macroscopic anatomy and microscopic anatomy. Gross anatomy is the study of structures large enough to be seen with the naked eye, and also includes superficial anatomy or surface anatomy, the study by sight of the external body features. Microscopic anatomy is the study of structures on a microscopic scale, along with histology (the study of tissues), and embryology (the study of an organism in its immature condition). Regional anatomy is the study of the interrelationships of all of the structures in a specific body region, such as the abdomen. In contrast, systemic anatomy is the study of the structures that make up a discrete body system---that is, a group of structures that work together to perform a unique body function, such as the digestive system.
Anatomy can be studied using both invasive and non-invasive methods with the goal of obtaining information about the structure and organization of organs and systems. Methods used include dissection, in which a body is opened and its organs studied, and endoscopy, in which a video camera-equipped instrument is inserted through a small incision in the body wall and used to explore the internal organs and other structures. Angiography using X-rays or magnetic resonance angiography are methods to visualize blood vessels.
The term \"anatomy\" is commonly taken to refer to human anatomy. However, substantially similar structures and tissues are found throughout the rest of the animal kingdom, and the term also includes the anatomy of other animals. The term *zootomy* is also sometimes used to specifically refer to non-human animals. The structure and tissues of plants are of a dissimilar nature and they are studied in plant anatomy.
## Animal tissues {#animal_tissues}
The kingdom Animalia contains multicellular organisms that are heterotrophic and motile (although some have secondarily adopted a sessile lifestyle). Most animals have bodies differentiated into separate tissues and these animals are also known as eumetazoans. They have an internal digestive chamber, with one or two openings; the gametes are produced in multicellular sex organs, and the zygotes include a blastula stage in their embryonic development. Metazoans do not include the sponges, which have undifferentiated cells.
Unlike plant cells, animal cells have neither a cell wall nor chloroplasts. Vacuoles, when present, are more in number and much smaller than those in the plant cell. The body tissues are composed of numerous types of cells, including those found in muscles, nerves and skin. Each typically has a cell membrane formed of phospholipids, cytoplasm and a nucleus. All of the different cells of an animal are derived from the embryonic germ layers. Those simpler invertebrates which are formed from two germ layers of ectoderm and endoderm are called diploblastic and the more developed animals whose structures and organs are formed from three germ layers are called triploblastic. All of a triploblastic animal\'s tissues and organs are derived from the three germ layers of the embryo, the ectoderm, mesoderm and endoderm.
Animal tissues can be grouped into four basic types: connective, epithelial, muscle and nervous tissue.
### Connective tissue {#connective_tissue}
Connective tissues are fibrous and made up of cells scattered among inorganic material called the extracellular matrix. Often called fascia (from the Latin \"fascia,\" meaning \"band\" or \"bandage\"), connective tissues give shape to organs and holds them in place. The main types are loose connective tissue, adipose tissue, fibrous connective tissue, cartilage and bone. The extracellular matrix contains proteins, the chief and most abundant of which is collagen. Collagen plays a major part in organizing and maintaining tissues. The matrix can be modified to form a skeleton to support or protect the body. An exoskeleton is a thickened, rigid cuticle which is stiffened by mineralization, as in crustaceans or by the cross-linking of its proteins as in insects. An endoskeleton is internal and present in all developed animals, as well as in many of those less developed.
### Epithelium
Epithelial tissue is composed of closely packed cells, bound to each other by cell adhesion molecules, with little intercellular space. Epithelial cells can be squamous (flat), cuboidal or columnar and rest on a basal lamina, the upper layer of the basement membrane, the lower layer is the reticular lamina lying next to the connective tissue in the extracellular matrix secreted by the epithelial cells. There are many different types of epithelium, modified to suit a particular function. In the respiratory tract there is a type of ciliated epithelial lining; in the small intestine there are microvilli on the epithelial lining and in the large intestine there are intestinal villi. Skin consists of an outer layer of keratinized stratified squamous epithelium that covers the exterior of the vertebrate body. Keratinocytes make up to 95% of the cells in the skin. The epithelial cells on the external surface of the body typically secrete an extracellular matrix in the form of a cuticle. In simple animals this may just be a coat of glycoproteins. In more advanced animals, many glands are formed of epithelial cells.
### Muscle tissue {#muscle_tissue}
Muscle cells (myocytes) form the active contractile tissue of the body. Muscle tissue functions to produce force and cause motion, either locomotion or movement within internal organs. Muscle is formed of contractile filaments and is separated into three main types; smooth muscle, skeletal muscle and cardiac muscle. Smooth muscle has no striations when examined microscopically. It contracts slowly but maintains contractibility over a wide range of stretch lengths. It is found in such organs as sea anemone tentacles and the body wall of sea cucumbers. Skeletal muscle contracts rapidly but has a limited range of extension. It is found in the movement of appendages and jaws. Obliquely striated muscle is intermediate between the other two. The filaments are staggered and this is the type of muscle found in earthworms that can extend slowly or make rapid contractions. In higher animals striated muscles occur in bundles attached to bone to provide movement and are often arranged in antagonistic sets. Smooth muscle is found in the walls of the uterus, bladder, intestines, stomach, oesophagus, respiratory airways, and blood vessels. Cardiac muscle is found only in the heart, allowing it to contract and pump blood round the body.
### Nervous tissue {#nervous_tissue}
Nervous tissue is composed of many nerve cells known as neurons which transmit information. In some slow-moving radially symmetrical marine animals such as ctenophores and cnidarians (including sea anemones and jellyfish), the nerves form a nerve net, but in most animals they are organized longitudinally into bundles. In simple animals, receptor neurons in the body wall cause a local reaction to a stimulus. In more complex animals, specialized receptor cells such as chemoreceptors and photoreceptors are found in groups and send messages along neural networks to other parts of the organism. Neurons can be connected together in ganglia. In higher animals, specialized receptors are the basis of sense organs and there is a central nervous system (brain and spinal cord) and a peripheral nervous system. The latter consists of sensory nerves that transmit information from sense organs and motor nerves that influence target organs. The peripheral nervous system is divided into the somatic nervous system which conveys sensation and controls voluntary muscle, and the autonomic nervous system which involuntarily controls smooth muscle, certain glands and internal organs, including the stomach.
## Vertebrate anatomy {#vertebrate_anatomy}
All vertebrates have a similar basic body plan and at some point in their lives, mostly in the embryonic stage, share the major chordate characteristics: a stiffening rod, the notochord; a dorsal hollow tube of nervous material, the neural tube; pharyngeal arches; and a tail posterior to the anus. The spinal cord is protected by the vertebral column and is above the notochord, and the gastrointestinal tract is below it. Nervous tissue is derived from the ectoderm, connective tissues are derived from mesoderm, and gut is derived from the endoderm. At the posterior end is a tail which continues the spinal cord and vertebrae but not the gut. The mouth is found at the anterior end of the animal, and the anus at the base of the tail. The defining characteristic of a vertebrate is the vertebral column, formed in the development of the segmented series of vertebrae. In most vertebrates the notochord becomes the nucleus pulposus of the intervertebral discs. However, a few vertebrates, such as the sturgeon and the coelacanth, retain the notochord into adulthood. Jawed vertebrates are typified by paired appendages, fins or legs, which may be secondarily lost. The limbs of vertebrates are considered to be homologous because the same underlying skeletal structure was inherited from their last common ancestor. This is one of the arguments put forward by Charles Darwin to support his theory of evolution.
### Fish anatomy {#fish_anatomy}
The body of a fish is divided into a head, trunk and tail, although the divisions between the three are not always externally visible. The skeleton, which forms the support structure inside the fish, is either made of cartilage, in cartilaginous fish, or bone in bony fish. The main skeletal element is the vertebral column, composed of articulating vertebrae which are lightweight yet strong. The ribs attach to the spine and there are no limbs or limb girdles. The main external features of the fish, the fins, are composed of either bony or soft spines called rays, which with the exception of the caudal fins, have no direct connection with the spine. They are supported by the muscles which compose the main part of the trunk. The heart has two chambers and pumps the blood through the respiratory surfaces of the gills and on round the body in a single circulatory loop. The eyes are adapted for seeing underwater and have only local vision. There is an inner ear but no external or middle ear. Low frequency vibrations are detected by the lateral line system of sense organs that run along the length of the sides of fish, and these respond to nearby movements and to changes in water pressure.
Sharks and rays are basal fish with numerous primitive anatomical features similar to those of ancient fish, including skeletons composed of cartilage. Their bodies tend to be dorso-ventrally flattened, they usually have five pairs of gill slits and a large mouth set on the underside of the head. The dermis is covered with separate dermal placoid scales. They have a cloaca into which the urinary and genital passages open, but not a swim bladder. Cartilaginous fish produce a small number of large, yolky eggs. Some species are ovoviviparous and the young develop internally but others are oviparous and the larvae develop externally in egg cases.
The bony fish lineage shows more derived anatomical traits, often with major evolutionary changes from the features of ancient fish. They have a bony skeleton, are generally laterally flattened, have five pairs of gills protected by an operculum, and a mouth at or near the tip of the snout. The dermis is covered with overlapping scales. Bony fish have a swim bladder which helps them maintain a constant depth in the water column, but not a cloaca. They mostly spawn a large number of small eggs with little yolk which they broadcast into the water column.
### Amphibian anatomy {#amphibian_anatomy}
Amphibians are a class of animals comprising frogs, salamanders and caecilians. They are tetrapods, but the caecilians and a few species of salamander have either no limbs or their limbs are much reduced in size. Their main bones are hollow and lightweight and are fully ossified and the vertebrae interlock with each other and have articular processes. Their ribs are usually short and may be fused to the vertebrae. Their skulls are mostly broad and short, and are often incompletely ossified. Their skin contains little keratin and lacks scales, but contains many mucous glands and in some species, poison glands. The hearts of amphibians have three chambers, two atria and one ventricle. They have a urinary bladder and nitrogenous waste products are excreted primarily as urea. Amphibians breathe by means of buccal pumping, a pump action in which air is first drawn into the buccopharyngeal region through the nostrils. These are then closed and the air is forced into the lungs by contraction of the throat. They supplement this with gas exchange through the skin which needs to be kept moist.
In frogs the pelvic girdle is robust and the hind legs are much longer and stronger than the forelimbs. The feet have four or five digits and the toes are often webbed for swimming or have suction pads for climbing. Frogs have large eyes and no tail. Salamanders resemble lizards in appearance; their short legs project sideways, the belly is close to or in contact with the ground and they have a long tail. Caecilians superficially resemble earthworms and are limbless. They burrow by means of zones of muscle contractions which move along the body and they swim by undulating their body from side to side.
### Reptile anatomy {#reptile_anatomy}
Reptiles are a class of animals comprising turtles, tuataras, lizards, snakes and crocodiles. They are tetrapods, but the snakes and a few species of lizard either have no limbs or their limbs are much reduced in size. Their bones are better ossified and their skeletons stronger than those of amphibians. The teeth are conical and mostly uniform in size. The surface cells of the epidermis are modified into horny scales which create a waterproof layer. Reptiles are unable to use their skin for respiration as do amphibians and have a more efficient respiratory system drawing air into their lungs by expanding their chest walls. The heart resembles that of the amphibian but there is a septum which more completely separates the oxygenated and deoxygenated bloodstreams. The reproductive system has evolved for internal fertilization, with a copulatory organ present in most species. The eggs are surrounded by amniotic membranes which prevents them from drying out and are laid on land, or develop internally in some species. The bladder is small as nitrogenous waste is excreted as uric acid.
Turtles are notable for their protective shells. They have an inflexible trunk encased in a horny carapace above and a plastron below. These are formed from bony plates embedded in the dermis which are overlain by horny ones and are partially fused with the ribs and spine. The neck is long and flexible and the head and the legs can be drawn back inside the shell. Turtles are vegetarians and the typical reptile teeth have been replaced by sharp, horny plates. In aquatic species, the front legs are modified into flippers.
**Tuataras** superficially resemble lizards but the lineages diverged in the Triassic period. There is one living species, *Sphenodon punctatus*. The skull has two openings (fenestrae) on either side and the jaw is rigidly attached to the skull. There is one row of teeth in the lower jaw and this fits between the two rows in the upper jaw when the animal chews. The teeth are merely projections of bony material from the jaw and eventually wear down. The brain and heart are more primitive than those of other reptiles, and the lungs have a single chamber and lack bronchi. The tuatara has a well-developed parietal eye on its forehead.
Lizards have skulls with only one fenestra on each side, the lower bar of bone below the second fenestra having been lost. This results in the jaws being less rigidly attached which allows the mouth to open wider. Lizards are mostly quadrupeds, with the trunk held off the ground by short, sideways-facing legs, but a few species have no limbs and resemble snakes. Lizards have moveable eyelids, eardrums are present and some species have a central parietal eye.
Snakes are closely related to lizards, having branched off from a common ancestral lineage during the Cretaceous period, and they share many of the same features. The skeleton consists of a skull, a hyoid bone, spine and ribs though a few species retain a vestige of the pelvis and rear limbs in the form of pelvic spurs. The bar under the second fenestra has also been lost and the jaws have extreme flexibility allowing the snake to swallow its prey whole. Snakes lack moveable eyelids, the eyes being covered by transparent \"spectacle\" scales. They do not have eardrums but can detect ground vibrations through the bones of their skull. Their forked tongues are used as organs of taste and smell and some species have sensory pits on their heads enabling them to locate warm-blooded prey.
Crocodilians are large, low-slung aquatic reptiles with long snouts and large numbers of teeth. The head and trunk are dorso-ventrally flattened and the tail is laterally compressed. It undulates from side to side to force the animal through the water when swimming. The tough keratinized scales provide body armour and some are fused to the skull. The nostrils, eyes and ears are elevated above the top of the flat head enabling them to remain above the surface of the water when the animal is floating. Valves seal the nostrils and ears when it is submerged. Unlike other reptiles, crocodilians have hearts with four chambers allowing complete separation of oxygenated and deoxygenated blood.
### Bird anatomy {#bird_anatomy}
Birds are tetrapods but though their hind limbs are used for walking or hopping, their front limbs are wings covered with feathers and adapted for flight. Birds are endothermic, have a high metabolic rate, a light skeletal system and powerful muscles. The long bones are thin, hollow and very light. Air sac extensions from the lungs occupy the centre of some bones. The sternum is wide and usually has a keel and the caudal vertebrae are fused. There are no teeth and the narrow jaws are adapted into a horn-covered beak. The eyes are relatively large, particularly in nocturnal species such as owls. They face forwards in predators and sideways in ducks.
The feathers are outgrowths of the epidermis and are found in localized bands from where they fan out over the skin. Large flight feathers are found on the wings and tail, contour feathers cover the bird\'s surface and fine down occurs on young birds and under the contour feathers of water birds. The only cutaneous gland is the single uropygial gland near the base of the tail. This produces an oily secretion that waterproofs the feathers when the bird preens. There are scales on the legs, feet and claws on the tips of the toes.
### Mammal anatomy {#mammal_anatomy}
Mammals are a diverse class of animals, mostly terrestrial but some are aquatic and others have evolved flapping or gliding flight. They mostly have four limbs, but some aquatic mammals have no limbs or limbs modified into fins, and the forelimbs of bats are modified into wings. The legs of most mammals are situated below the trunk, which is held well clear of the ground. The bones of mammals are well ossified and their teeth, which are usually differentiated, are coated in a layer of prismatic enamel. The teeth are shed once (milk teeth) during the animal\'s lifetime or not at all, as is the case in cetaceans. Mammals have three bones in the middle ear and a cochlea in the inner ear. They are clothed in hair and their skin contains glands which secrete sweat. Some of these glands are specialized as mammary glands, producing milk to feed the young. Mammals breathe with lungs and have a muscular diaphragm separating the thorax from the abdomen which helps them draw air into the lungs. The mammalian heart has four chambers, and oxygenated and deoxygenated blood are kept entirely separate. Nitrogenous waste is excreted primarily as urea.
Mammals are amniotes, and most are viviparous, giving birth to live young. Exceptions to this are the egg-laying monotremes, the platypus and the echidnas of Australia. Most other mammals have a placenta through which the developing foetus obtains nourishment, but in marsupials, the foetal stage is very short and the immature young is born and finds its way to its mother\'s pouch where it latches on to a teat and completes its development.
#### Human anatomy {#human_anatomy}
Humans have the overall body plan of a mammal. Humans have a head, neck, trunk (which includes the thorax and abdomen), two arms and hands, and two legs and feet.
Generally, students of certain biological sciences, paramedics, prosthetists and orthotists, physiotherapists, occupational therapists, nurses, podiatrists, and medical students learn gross anatomy and microscopic anatomy from anatomical models, skeletons, textbooks, diagrams, photographs, lectures and tutorials and in addition, medical students generally also learn gross anatomy through practical experience of dissection and inspection of cadavers. The study of microscopic anatomy (or histology) can be aided by practical experience examining histological preparations (or slides) under a microscope.
Human anatomy, physiology and biochemistry are complementary basic medical sciences, which are generally taught to medical students in their first year at medical school. Human anatomy can be taught regionally or systemically; that is, respectively, studying anatomy by bodily regions such as the head and chest, or studying by specific systems, such as the nervous or respiratory systems. The major anatomy textbook, Gray\'s Anatomy, has been reorganized from a systems format to a regional format, in line with modern teaching methods. A thorough working knowledge of anatomy is required by physicians, especially surgeons and doctors working in some diagnostic specialties, such as histopathology and radiology.
Academic anatomists are usually employed by universities, medical schools or teaching hospitals. They are often involved in teaching anatomy, and research into certain systems, organs, tissues or cells.
## Invertebrate anatomy {#invertebrate_anatomy}
Invertebrates constitute a vast array of living organisms ranging from the simplest unicellular eukaryotes such as *Paramecium* to such complex multicellular animals as the octopus, lobster and dragonfly. They constitute about 95% of the animal species. By definition, none of these creatures has a backbone. The cells of single-cell protozoans have the same basic structure as those of multicellular animals but some parts are specialized into the equivalent of tissues and organs. Locomotion is often provided by cilia or flagella or may proceed via the advance of pseudopodia, food may be gathered by phagocytosis, energy needs may be supplied by photosynthesis and the cell may be supported by an endoskeleton or an exoskeleton. Some protozoans can form multicellular colonies.
Metazoans are a multicellular organism, with different groups of cells serving different functions. The most basic types of metazoan tissues are epithelium and connective tissue, both of which are present in nearly all invertebrates. The outer surface of the epidermis is normally formed of epithelial cells and secretes an extracellular matrix which provides support to the organism. An endoskeleton derived from the mesoderm is present in echinoderms, sponges and some cephalopods. Exoskeletons are derived from the epidermis and is composed of chitin in arthropods (insects, spiders, ticks, shrimps, crabs, lobsters). Calcium carbonate constitutes the shells of molluscs, brachiopods and some tube-building polychaete worms and silica forms the exoskeleton of the microscopic diatoms and radiolaria. Other invertebrates may have no rigid structures but the epidermis may secrete a variety of surface coatings such as the pinacoderm of sponges, the gelatinous cuticle of cnidarians (polyps, sea anemones, jellyfish) and the collagenous cuticle of annelids. The outer epithelial layer may include cells of several types including sensory cells, gland cells and stinging cells. There may also be protrusions such as microvilli, cilia, bristles, spines and tubercles.
Marcello Malpighi, the father of microscopical anatomy, discovered that plants had tubules similar to those he saw in insects like the silk worm. He observed that when a ring-like portion of bark was removed on a trunk a swelling occurred in the tissues above the ring, and he unmistakably interpreted this as growth stimulated by food coming down from the leaves, and being captured above the ring.
### Arthropod anatomy {#arthropod_anatomy}
Arthropods comprise the largest phylum of invertebrates in the animal kingdom with over a million known species.
Insects possess segmented bodies supported by a hard-jointed outer covering, the exoskeleton, made mostly of chitin. The segments of the body are organized into three distinct parts, a head, a thorax and an abdomen. The head typically bears a pair of sensory antennae, a pair of compound eyes, one to three simple eyes (ocelli) and three sets of modified appendages that form the mouthparts. The thorax has three pairs of segmented legs, one pair each for the three segments that compose the thorax and one or two pairs of wings. The abdomen is composed of eleven segments, some of which may be fused and houses the digestive, respiratory, excretory and reproductive systems. There is considerable variation between species and many adaptations to the body parts, especially wings, legs, antennae and mouthparts.
Spiders a class of arachnids have four pairs of legs; a body of two segments---a cephalothorax and an abdomen. Spiders have no wings and no antennae. They have mouthparts called chelicerae which are often connected to venom glands as most spiders are venomous. They have a second pair of appendages called pedipalps attached to the cephalothorax. These have similar segmentation to the legs and function as taste and smell organs. At the end of each male pedipalp is a spoon-shaped cymbium that acts to support the copulatory organ.
## Other branches of anatomy {#other_branches_of_anatomy}
- Surface anatomy is important as the study of anatomical landmarks that can be readily seen from the exterior contours of the body. It enables medics and veterinarians to gauge the position and anatomy of the associated deeper structures. Superficial is a directional term that indicates that structures are located relatively close to the surface of the body.
- Comparative anatomy relates to the comparison of anatomical structures (both gross and microscopic) in different animals.
- Artistic anatomy relates to anatomic studies of body proportions for artistic reasons.
## History
### Ancient
thumb\|upright=1.05\|Image of early rendition of anatomy findings
In 1600 BCE, the Edwin Smith Papyrus, an Ancient Egyptian medical text, described the heart and its vessels, as well as the brain and its meninges and cerebrospinal fluid, and the liver, spleen, kidneys, uterus and bladder. It showed the blood vessels diverging from the heart. The Ebers Papyrus (c. 1550 BCE) features a \"treatise on the heart\", with vessels carrying all the body\'s fluids to or from every member of the body.
Ancient Greek anatomy and physiology underwent great changes and advances throughout the early medieval world. Over time, this medical practice expanded due to a continually developing understanding of the functions of organs and structures in the body. Phenomenal anatomical observations of the human body were made, which contributed to the understanding of the brain, eye, liver, reproductive organs, and nervous system.
The Hellenistic Egyptian city of Alexandria was the stepping-stone for Greek anatomy and physiology. Alexandria not only housed the biggest library for medical records and books of the liberal arts in the world during the time of the Greeks but was also home to many medical practitioners and philosophers. Great patronage of the arts and sciences from the Ptolemaic dynasty of Egypt helped raise Alexandria up, further rivalling other Greek states\' cultural and scientific achievements.
Some of the most striking advances in early anatomy and physiology took place in Hellenistic Alexandria. Two of the most famous anatomists and physiologists of the third century were Herophilus and Erasistratus. These two physicians helped pioneer human dissection for medical research, using the cadavers of condemned criminals, which was considered taboo until the Renaissance---Herophilus was recognized as the first person to perform systematic dissections. Herophilus became known for his anatomical works, making impressive contributions to many branches of anatomy and many other aspects of medicine. Some of the works included classifying the system of the pulse, the discovery that human arteries had thicker walls than veins, and that the atria were parts of the heart. Herophilus\'s knowledge of the human body has provided vital input towards understanding the brain, eye, liver, reproductive organs, and nervous system and characterizing the course of the disease. Erasistratus accurately described the structure of the brain, including the cavities and membranes, and made a distinction between its cerebrum and cerebellum During his study in Alexandria, Erasistratus was particularly concerned with studies of the circulatory and nervous systems. He could distinguish the human body\'s sensory and motor nerves and believed air entered the lungs and heart, which was then carried throughout the body. His distinction between the arteries and veins---the arteries carrying the air through the body, while the veins carry the blood from the heart was a great anatomical discovery. Erasistratus was also responsible for naming and describing the function of the epiglottis and the heart\'s valves, including the tricuspid. During the third century, Greek physicians were able to differentiate nerves from blood vessels and tendons and to realize that the nerves convey neural impulses. It was Herophilus who made the point that damage to motor nerves induced paralysis. Herophilus named the meninges and ventricles in the brain, appreciated the division between cerebellum and cerebrum and recognized that the brain was the \"seat of intellect\" and not a \"cooling chamber\" as propounded by Aristotle Herophilus is also credited with describing the optic, oculomotor, motor division of the trigeminal, facial, vestibulocochlear and hypoglossal nerves.
Incredible feats were made during the third century BCE in both the digestive and reproductive systems. Herophilus discovered and described not only the salivary glands but also the small intestine and liver. He showed that the uterus is a hollow organ and described the ovaries and uterine tubes. He recognized that spermatozoa were produced by the testes and was the first to identify the prostate gland.
The anatomy of the muscles and skeleton is described in the *Hippocratic Corpus*, an Ancient Greek medical work written by unknown authors. Aristotle described vertebrate anatomy based on animal dissection. Praxagoras identified the difference between arteries and veins. Also in the 4th century BCE, Herophilos and Erasistratus produced more accurate anatomical descriptions based on vivisection of criminals in Alexandria during the Ptolemaic period.
In the 2nd century, Galen of Pergamum, an anatomist, clinician, writer, and philosopher, wrote the final and highly influential anatomy treatise of ancient times. He compiled existing knowledge and studied anatomy through the dissection of animals. He was one of the first experimental physiologists through his vivisection experiments on animals. Galen\'s drawings, based mostly on dog anatomy, became effectively the only anatomical textbook for the next thousand years. His work was known to Renaissance doctors only through Islamic Golden Age medicine until it was translated from Greek sometime in the 15th century.
### Medieval to early modern {#medieval_to_early_modern}
Anatomy developed little from classical times until the sixteenth century; as the historian Marie Boas writes, \"Progress in anatomy before the sixteenth century is as mysteriously slow as its development after 1500 is startlingly rapid\". Between 1275 and 1326, the anatomists Mondino de Luzzi, Alessandro Achillini and Antonio Benivieni at Bologna carried out the first systematic human dissections since ancient times. Mondino\'s *Anatomy* of 1316 was the first textbook in the medieval rediscovery of human anatomy. It describes the body in the order followed in Mondino\'s dissections, starting with the abdomen, thorax, head, and limbs. It was the standard anatomy textbook for the next century.
Leonardo da Vinci (1452--1519) was trained in anatomy by Andrea del Verrocchio. He made use of his anatomical knowledge in his artwork, making many sketches of skeletal structures, muscles and organs of humans and other vertebrates that he dissected.
Andreas Vesalius (1514--1564), professor of anatomy at the University of Padua, is considered the founder of modern human anatomy. Originally from Brabant, Vesalius published the influential book *De humani corporis fabrica* (\"the structure of the human body\"), a large format book in seven volumes, in 1543. The accurate and intricately detailed illustrations, often in allegorical poses against Italianate landscapes, are thought to have been made by the artist Jan van Calcar, a pupil of Titian.
In England, anatomy was the subject of the first public lectures given in any science; these were provided by the Company of Barbers and Surgeons in the 16th century, joined in 1583 by the Lumleian lectures in surgery at the Royal College of Physicians.
### Late modern {#late_modern}
Medical schools began to be set up in the United States towards the end of the 18th century. Classes in anatomy needed a continual stream of cadavers for dissection, and these were difficult to obtain. Philadelphia, Baltimore, and New York were all renowned for body snatching activity as criminals raided graveyards at night, removing newly buried corpses from their coffins. A similar problem existed in Britain where demand for bodies became so great that grave-raiding and even anatomy murder were practised to obtain cadavers. Some graveyards were, in consequence, protected with watchtowers. The practice was halted in Britain by the Anatomy Act of 1832, while in the United States, similar legislation was enacted after the physician William S. Forbes of Jefferson Medical College was found guilty in 1882 of \"complicity with resurrectionists in the despoliation of graves in Lebanon Cemetery\".
The teaching of anatomy in Britain was transformed by Sir John Struthers, Regius Professor of Anatomy at the University of Aberdeen from 1863 to 1889. He was responsible for setting up the system of three years of \"pre-clinical\" academic teaching in the sciences underlying medicine, including especially anatomy. This system lasted until the reform of medical training in 1993 and 2003. As well as teaching, he collected many vertebrate skeletons for his museum of comparative anatomy, published over 70 research papers, and became famous for his public dissection of the Tay Whale. From 1822 the Royal College of Surgeons regulated the teaching of anatomy in medical schools. Medical museums provided examples in comparative anatomy, and were often used in teaching. Ignaz Semmelweis investigated puerperal fever and he discovered how it was caused. He noticed that the frequently fatal fever occurred more often in mothers examined by medical students than by midwives. The students went from the dissecting room to the hospital ward and examined women in childbirth. Semmelweis showed that when the trainees washed their hands in chlorinated lime before each clinical examination, the incidence of puerperal fever among the mothers could be reduced dramatically. Before the modern medical era, the primary means for studying the internal structures of the body were dissection of the dead and inspection, palpation, and auscultation of the living. The advent of microscopy opened up an understanding of the building blocks that constituted living tissues. Technical advances in the development of achromatic lenses increased the resolving power of the microscope, and around 1839, Matthias Jakob Schleiden and Theodor Schwann identified that cells were the fundamental unit of organization of all living things. The study of small structures involved passing light through them, and the microtome was invented to provide sufficiently thin slices of tissue to examine. Staining techniques using artificial dyes were established to help distinguish between different tissue types. Advances in the fields of histology and cytology began in the late 19th century along with advances in surgical techniques allowing for the painless and safe removal of biopsy specimens. The invention of the electron microscope brought a significant advance in resolution power and allowed research into the ultrastructure of cells and the organelles and other structures within them. About the same time, in the 1950s, the use of X-ray diffraction for studying the crystal structures of proteins, nucleic acids, and other biological molecules gave rise to a new field of molecular anatomy.
Equally important advances have occurred in *non-invasive* techniques for examining the body\'s interior structures. X-rays can be passed through the body and used in medical radiography and fluoroscopy to differentiate interior structures that have varying degrees of opaqueness. Magnetic resonance imaging, computed tomography, and ultrasound imaging have all enabled the examination of internal structures in unprecedented detail to a degree far beyond the imagination of earlier generations.
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Affirming the consequent
|
In propositional logic, **affirming the consequent** (also known as **converse error**, **fallacy of the converse**, or **confusion of necessity and sufficiency**) is a formal fallacy (or an invalid form of argument) that is committed when, in the context of an indicative conditional statement, it is stated that because the consequent is true, therefore the antecedent is true. It takes on the following form:
:
: If *P*, then *Q*.
: *Q*.
: Therefore, *P*.
which may also be phrased as
: $P \rightarrow Q$ (P implies Q)
: $\therefore Q \rightarrow P$ (therefore, Q implies P)
For example, it may be true that a broken lamp would cause a room to become dark. It is not true, however, that a dark room implies the presence of a broken lamp. There may be no lamp (or any light source). The lamp may also be off. In other words, the consequent (a dark room) can have other antecedents (no lamp, off-lamp), and so can still be true even if the stated antecedent is not.
Converse errors are common in everyday thinking and communication and can result from, among other causes, communication issues, misconceptions about logic, and failure to consider other causes.
A related fallacy is denying the antecedent. Two related *valid* forms of logical argument include *modus tollens* (denying the consequent) and *modus ponens* (affirming the antecedent).
## Formal description {#formal_description}
Affirming the consequent is the action of taking a true statement $P \to Q$ and invalidly concluding its converse $Q \to P$. The name *affirming the consequent* derives from using the consequent, *Q*, of $P \to Q$, to conclude the antecedent *P*. This fallacy can be summarized formally as $(P \to Q, Q)\to P$ or, alternatively, $\frac{P \to Q, Q}{\therefore P}$. The root cause of such a logical error is sometimes failure to realize that just because *P* is a *possible* condition for *Q*, *P* may not be the *only* condition for *Q*, i.e. *Q* may follow from another condition as well.
Affirming the consequent can also result from overgeneralizing the experience of many statements *having* true converses. If *P* and *Q* are \"equivalent\" statements, i.e. $P \leftrightarrow Q$, it *is* possible to infer *P* under the condition *Q*. For example, the statements \"It is August 13, so it is my birthday\" $P \to Q$ and \"It is my birthday, so it is August 13\" $Q \to P$ are equivalent and both true consequences of the statement \"August 13 is my birthday\" (an abbreviated form of $P \leftrightarrow Q$).
Of the possible forms of \"mixed hypothetical syllogisms,\" two are valid and two are invalid. Affirming the antecedent (modus ponens) and denying the consequent (modus tollens) are valid. Affirming the consequent and denying the antecedent are invalid.
## Additional examples {#additional_examples}
**Example 1**
One way to demonstrate the invalidity of this argument form is with a counterexample with true premises but an obviously false conclusion. For example:
: If someone lives in San Diego, then they live in California.
: Joe lives in California.
: Therefore, Joe lives in San Diego.
There are many places to live in California other than San Diego. On the other hand, one can affirm with certainty that \"if someone does not live in California\" (*non-Q*), then \"this person does not live in San Diego\" (*non-P*). This is the contrapositive of the first statement, and it must be true if and only if the original statement is true.
**Example 2**
: If an animal is a dog, then it has four legs.
: My cat has four legs.
: Therefore, my cat is a dog.
Here, it is immediately intuitive that any number of other antecedents (\"If an animal is a deer\...\", \"If an animal is an elephant\...\", \"If an animal is a moose\...\", *etc.*) can give rise to the consequent (\"then it has four legs\"), and that it is preposterous to suppose that having four legs *must* imply that the animal is a dog and nothing else. This is useful as a teaching example since most people can immediately recognize that the conclusion reached must be wrong (intuitively, a cat cannot be a dog), and that the method by which it was reached must therefore be fallacious. This argument was featured in Euguene Ionesco\'s Rhinoceros in a conversation between a Logician and an Old Gentleman.
**Example 3**
In *Catch-22*, the chaplain is interrogated for supposedly being \"Washington Irving\"/\"Irving Washington\", who has been blocking out large portions of soldiers\' letters home. The colonel has found such a letter, but with the chaplain\'s name signed.
: \"You can read, though, can\'t you?\" the colonel persevered sarcastically. \"The author signed his name.\"
: \"That\'s my name there.\"
: \"Then you wrote it. Q.E.D.\"
*P* in this case is \'The chaplain signs his own name\', and *Q* \'The chaplain\'s name is written\'. The chaplain\'s name may be written, but he did not necessarily write it, as the colonel falsely concludes.\'\'
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Politics of Angola
|
The current political regime in Angola is presidentialism, in which the President of the Republic is also head of state and government; it is advised by a Council of Ministers, which together with the President form the national executive power. Legislative power rests with the 220 parliamentarians elected to the National Assembly. The President of the Republic, together with the parliament, appoints the majority of the members of the two highest bodies of the judiciary, that is, the Constitutional Court and the Supreme Court. The judiciary is still made up of the Court of Auditors and the Supreme Military Court.
The Angolan government is composed of three branches of government: executive, legislative and judicial. For decades, political power has been concentrated in the presidency with the People\'s Movement for the Liberation of Angola. `{{Politics of Angola}}`{=mediawiki}
## History
Since the adoption of a new constitution in 2010, the politics of Angola takes place in a framework of a presidential republic, whereby the President of Angola is both head of state and head of government, and of a multi-party system. Executive power is exercised by the government. Legislative power is vested in the President, the government and parliament.
Angola changed from a one-party Marxist-Leninist system ruled by the Popular Movement for the Liberation of Angola (MPLA), in place since independence in 1975, to a multiparty democracy based on a new constitution adopted in 1992. That same year the first parliamentary and presidential elections were held. The MPLA won an absolute majority in the parliamentary elections. In the presidential elections, President José Eduardo dos Santos won the first round election with more than 49% of the vote to Jonas Savimbi\'s 40%. A runoff election would have been necessary, but never took place. The renewal of civil war immediately after the elections, which were considered as fraudulent by UNITA, and the collapse of the Lusaka Protocol, created a split situation. To a certain degree the new democratic institutions worked, notably the National Assembly, with the active participation of UNITA\'s and the FNLA\'s elected MPs - while José Eduardo dos Santos continued to exercise his functions without democratic legitimation. However the armed forces of the MPLA (now the official armed forces of the Angolan state) and of UNITA fought each other until the leader of UNITA, Jonas Savimbi, was killed in action in 2002.
From 2002 to 2010, the system as defined by the constitution of 1992 functioned in a relatively normal way. The executive branch of the government was composed of the President, the Prime Minister and Council of Ministers. The Council of Ministers, composed of all ministers and vice ministers, met regularly to discuss policy issues. Governors of the 18 provinces were appointed by and served at the pleasure of the president. The Constitutional Law of 1992 established the broad outlines of government structure and the rights and duties of citizens. The legal system was based on Portuguese and customary law but was weak and fragmented. Courts operated in only 12 of more than 140 municipalities. A Supreme Court served as the appellate tribunal; a Constitutional Court with powers of judicial review was never constituted despite statutory authorization. In practice, power was more and more concentrated in the hands of the President who, supported by an ever-increasing staff, largely controlled parliament, government, and the judiciary.
The 26-year-long civil war has ravaged the country\'s political and social institutions. The UN estimates of 1.8 million internally displaced persons (IDPs), while generally the accepted figure for war-affected people is 4 million. Daily conditions of life throughout the country and specifically Luanda (population approximately 6 million) mirror the collapse of administrative infrastructure as well as many social institutions. The ongoing grave economic situation largely prevents any government support for social institutions. Hospitals are without medicines or basic equipment, schools are without books, and public employees often lack the basic supplies for their day-to-day work.
José Eduardo dos Santos stepped down as President of Angola after 38 years in 2017, being peacefully succeeded by João Lourenço, Santos\' chosen successor. However, President João Lourenço started a campaign against corruption of the dos Santos era. In November 2017, Isabel dos Santos, the billionaire daughter of former President José Eduardo dos Santos, was fired from her position as head of the country\'s state oil company Sonangol. In August 2020, José Filomeno dos Santos, son of Angola\'s former president, was sentenced for five years in jail for fraud and corruption.
In August 2022, the ruling party, MPLA, won another outright majority and President Joao Lourenco won a second five-year term in the election. However, the election was the tightest in Angola\'s history.
## Executive branch {#executive_branch}
The 2010 constitution grants the President almost absolute power. Elections for the National assembly are to take place every five years, and the President is automatically the leader of the winning party or coalition. It is for the President to appoint (and dismiss) all of the following:
- The members of the government (state ministers, ministers, state secretaries and vice-ministers);
- The members of the Constitutional Court;
- The members of the Supreme Court;
- The members of the Court of Auditors;
- The members of the Military Supreme Court;
- The Governor and Vice-Governors of the National Angolan Bank;
- The General-Attorney, the Vice-General-Attorneys and their deputies (as well as the military homologous);
- The Governors of the provinces;
- The members of the Republic Council;
- The members of the National Security Council;
- The members of the Superior Magistrates Councils;
- The General Chief of the Armed Forces and his deputy;
- All other command posts in the military;
- The Police General Commander, and the 2nd in command;
- All other command posts in the police;
- The chiefs and directors of the intelligence and security organs.
The President is also provided a variety of powers, like defining the policy of the country. Even though it\'s not up to him/her to make laws (only to promulgate them and make edicts), the President is the leader of the winning party. The only \"relevant\" post that is not directly appointed by the President is the vice-president, which is the second in the winning party.
José Eduardo dos Santos stepped down as President of Angola after 38 years in 2017, being peacefully succeeded by João Lourenço, Santos\' chosen successor.
## Legislative branch {#legislative_branch}
The National Assembly (*Assembleia Nacional*) has 223 members, elected for a four-year term, 130 members by proportional representation, 90 members in provincial districts, and 3 members to represent Angolans abroad. The general elections in 1997 were rescheduled for 5 September 2008. The ruling party MPLA won 82% (191 seats in the National Assembly) and the main opposition party won only 10% (16 seats). The elections however have been described as only partly free but certainly not fair. A White Book on the elections in 2008 lists up all irregularities surrounding the Parliamentary elections of 2008.
## Political parties and elections {#political_parties_and_elections}
## Judicial branch {#judicial_branch}
Supreme Court (or \"Tribunal da Relacao\") judges of the Supreme Court are appointed by the president. The Constitutional Court, with the power of judicial review, contains 11 justices. Four are appointed by the President, four by the National Assembly, two by the Superior Council of the Judiciary, and one elected by the public.
## Administrative divisions {#administrative_divisions}
Angola has eighteen provinces: Bengo, Benguela, Bie, Cabinda, Cuando Cubango, Cuanza Norte, Cuanza Sul, Cunene, Huambo, Huila, Luanda, Lunda Norte, Lunda Sul, Malanje, Moxico, Namibe, Uige, Zaire
## Political pressure groups and leaders {#political_pressure_groups_and_leaders}
Front for the Liberation of the Enclave of Cabinda or FLEC (Henrique N\'zita Tiago; António Bento Bembe)
- *note:* FLEC is waging a small-scale, highly factionalized, armed struggle for the independence of Cabinda Province
## International organization participation {#international_organization_participation}
African, Caribbean and Pacific Group of States, AfDB, CEEAC, United Nations Economic Commission for Africa, FAO, Group of 77, IAEA, IBRD, ICAO, International Criminal Court (signatory), ICFTU, International Red Cross and Red Crescent Movement, International Development Association, IFAD, IFC, IFRCS, International Labour Organization, International Monetary Fund, International Maritime Organization, Interpol, IOC, International Organization for Migration, ISO (correspondent), ITU, Non-Aligned Council (temporary), UNCTAD, UNESCO, UNIDO, UPU, World Customs Organization, World Federation of Trade Unions, WHO, WIPO, WMO, WToO, WTrO
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Transport in Angola
|
**Transport in Angola** comprises:
## Roads
Two trans-African automobile routes pass through Angola:
- the Tripoli-Cape Town Highway
- the Beira-Lobito Highway
Map of Trans-African Highways.PNG\|Map of Trans-African Highways.
Walking home.jpg\|Walking home on EN 105. Tired are they.jpg\|Donkey-drawn carts. Transportation Jingu.jpg\|Three-wheeled motorcycles. The riches transportation.jpg\|Trucks. Midd Town Luanda.jpg\|Automobiles in Luanda. The Nowhere road.jpg\|New highway (2019).
## Railways
There are three separate railway lines in Angola:
- Luanda Railway (CFL) (northern);
- Benguela Railway (CFB) (central), operated by the Lobito Atlantic Railway joint venture;
- Moçâmedes Railway (CFM) (southern);
Reconstruction of these three lines began in 2005 and they are now all operational. The Benguela Railway connects to the Democratic Republic of the Congo.
## Waterways
- 1,300 km navigable (2008)
: *country comparison to the world:* 36
## Pipelines
- gas 352 km; liquid petroleum gas 85 km; crude oil 1,065 km (2013)
In April 2012, the Zambian Development Agency (ZDA) and an Angolan company signed a memorandum of understanding (MoU) to build a multi-product pipeline from Lobito to Lusaka, Zambia, to deliver various refined products to Zambia.
Angola plans to build an oil refinery in Lobito in the coming years.
## Ports and harbors {#ports_and_harbors}
The government plans to build a deep-water port at Barra do Dande, north of Luanda, in Bengo province near Caxito.
## Merchant marine {#merchant_marine}
- *total:* 58
: *country comparison to the world:* 115
- *by type:* cargo 13, oil tanker 8, other 37 (2008)
## Airports
- 102 (2021)
The old airport in Luanda, Quatro de Fevereiro Airport, will be replaced by the new Dr. Antonio Agostinho Neto International Airport.
### Airports -- with paved runways {#airports_with_paved_runways}
- *total:* 30
- *over 3,047 m:* 5
- *2,438 to 3,047 m:* 8
- *1,524 to 2,437 m:* 12
- *914 to 1,523 m:* 4
- *under 914 m:* 1 (2008)
### Airports -- with unpaved runways {#airports_with_unpaved_runways}
- *total:* 181 (2008)
- *over 3,047 m:* 2
- *2,438 to 3,047 m:* 5
- *1,524 to 2,437 m:* 32
- *914 to 1,523 m:* 100
- *under 914 m:* 42 (2008)
### Angolan Airlines {#angolan_airlines}
- TAAG Angola Airlines
- Sonair
- Fly Angola
### Heliports
- *total:* 1 (2021)
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Angolan Armed Forces
|
The **Angolan Armed Forces** (*Forças Armadas Angolanas*) or **FAA** is the military of Angola. The FAA consist of the Angolan Army (*Exército Angolano*), the Angolan Navy (*Marinha de Guerra Angolana*) and the National Air Force of Angola (*Força Aérea Nacional de Angola*). Reported total manpower in 2021 was about 107,000. The FAA is headed by the Chief of the General Staff António Egídio de Sousa Santos since 2018, who reports to the minister of National Defense, currently João Ernesto dos Santos.
## History
### Roots
The FAA succeeded to the previous People\'s Armed Forces for the Liberation of Angola (FAPLA) following the abortive Bicesse Accord with the Armed Forces of the Liberation of Angola (FALA), armed wing of the National Union for the Total Independence of Angola (UNITA). As part of the peace agreement, troops from both armies were to be demilitarized and then integrated. Integration was never completed as UNITA and FALA went back to war in 1992. Later, consequences for FALA personnel in Luanda were harsh with FAPLA veterans persecuting their erstwhile opponents in certain areas and reports of vigilantism.
### Founding
The Angolan Armed Forces were created on 9 October 1991. The institutionalization of the FAA was made in the Bicesse Accords, signed in 1991, between the Angolan Government and UNITA. The principles that would govern the FAA were defined in a joint proposal presented on September 24, 1991, and approved on 9 October. On 14 November 1991, Generals João Baptista de Matos and Abílio Kamalata Numa were appointed to the Superior Command of the Armed Forces. The ceremony took place at the Hotel Presidente Luanda, and was presided over by the then-minister França Vandúnem.
## Branches
### Army
The Army (*Exército*) is the land component of the FAA. It is organized in six military regions (Cabinda, Luanda, North, Center, East and South), with an infantry division being based in each one. Distributed by the six military regions / infantry divisions, there are 25 motorized infantry brigades, one tank brigade and one engineering brigade. The Army also includes an artillery regiment, the Military Artillery School, the Army Military Academy, an anti-aircraft defense group, a composite land artillery group, a military police regiment, a logistical transportation regiment and a field artillery brigade. The Army further includes the Special Forces Brigade (including Commandos and Special Operations units), but this unit is under the direct command of the General Staff of the FAA.
### Air Force {#air_force}
The National Air Force of Angola (FANA, *Força Aérea Nacional de Angola*) is the air component of the FAA. It is organized in six aviation regiments, each including several squadrons. To each of the regiments correspond an air base. Besides the aviation regiments, there is also a Pilot Training School.
The Air Force\'s personnel total about 8,000; its equipment includes transport aircraft and six Russian-manufactured Sukhoi Su-27 fighter aircraft. In 2002, one was lost during the civil war with UNITA forces.
In 1991, the Air Force/Air Defense Forces had 8,000 personnel and 90 combat-capable aircraft, including 22 fighters, 59 fighter ground attack aircraft and 16 attack helicopters.
### Navy
The Angola Navy (MGA, *Marinha de Guerra de Angola*) is the naval component of the FAA. It is organized in two naval zones (North and South), with naval bases in Luanda, Lobito and Moçâmedes. It includes a Marines Brigade and a Marines School, based in Ambriz. The Navy numbers about 1,000 personnel and operates only a handful of small patrol craft and barges.
The Navy has been neglected and ignored as a military arm mainly due to the guerrilla struggle against the Portuguese and the nature of the civil war. From the early 1990s to the present the Angolan Navy has shrunk from around 4,200 personnel to around 1,000, resulting in the loss of skills and expertise needed to maintain equipment. Portugal has been providing training through its Technical Military Cooperation (CTM) programme. The Navy is requesting procurement of a frigate, three corvettes, three offshore patrol vessel and additional fast patrol boats.
Most of the vessels in the navy\'s inventory dates back from the 1980s or earlier, and many of its ships are inoperable due to age and lack of maintenance. However the navy acquired new boats from Spain and France in the 1990s. Germany has delivered several Fast Attack Craft for border protection in 2011.
In September 2014 it was reported that the Angolan Navy would acquire seven Macaé-class patrol vessels from Brazil as part of a Technical Memorandum of Understanding (MoU) covering the production of the vessels as part of Angola\'s Naval Power Development Programme (Pronaval). The military of Angola aims to modernize its naval capability, presumably due to a rise in maritime piracy within the Gulf of Guinea which may have an adverse effect on the country\'s economy.
The navy\'s current known inventory includes the following:
- Fast attack craft
- 4 Mandume class craft (Bazan Cormoran type, refurbished in 2009)
- Patrol boats
- 3 18.3m long Patrulheiro patrol boats (refurbished in 2002)
- 5 ARESA PVC-170
- 2 Namacurra-class harbour patrol boats
- Fisheries Patrol Boats
- Ngola Kiluange and Nzinga Mbandi (delivered in September and October 2012 from Damen Shipyards)(Operated by Navy personnel under the Ministry of Agriculture, Rural Development and Fisheries)
- 28-metre FRV 2810 (Pensador) (Operated by Navy personnel under the Ministry of Agriculture, Rural Development and Fisheries)
- Landing craft
- LDM-400 -- 1 or 3 (reportedly has serviceability issues)
- Coastal defense equipment (CRTOC)
- SS-C1 Sepal radar system
The navy also has several aircraft for maritime patrol:
Aircraft Origin Type Versions In service Notes
------------ --------------- ------------------ ---------- ------------ -------
Fokker F27 Netherlands Medium transport 2
EMB 111 Brazil Maritime patrol 6
Boeing 707 United States Maritime patrol 1
## Specialized units {#specialized_units}
### Special forces {#special_forces}
The FAA include several types of special forces, namely the Commandos, the Special Operations and the Marines. The Angolan special forces follow the general model of the analogous Portuguese special forces, receiving similar training.
The Commandos and the Special forces are part of the Special Forces Brigade (BRIFE, *Brigada de Forças Especiais*), based at Cabo Ledo, in the Bengo Province. The BRIFE includes two battalions of commandos, a battalion of special operations and sub-units of combat support and service support. The BRIFE also included the Special Actions Group (GAE, *Grupo de Ações Especiais*), which is presently inactive and that was dedicated to long range reconnaissance, covert and sabotage operations. In the Cabo Ledo base is also installed the Special Forces Training School (EFFE, *Escola de Formação de Forças Especiais*). Both the BRIFE and the EFFE are directly under the Directorate of Special Forces of the General Staff of the Armed Forces.
The marines (*fuzileiros navais*) constitute the Marines Brigade of the Angolan Navy. The Marines Brigade is not permanently dependent of the Directorate of Special Forces, but can detach their units and elements to be put under the command of that body for the conduction of exercises or real operations. The Marines have a special forces unit known as Special Operations Marines(FOE, Fuzileiros Operaçües Especiais).
Since the disbandment of the Angolan Parachute Battalion in 2004, the FAA do not have a specialized paratrooper unit. However, elements of the commandos, special operations and marines are parachute qualified.
### Territorial troops {#territorial_troops}
The Directorate of People\'s Defense and Territorial Troops of the Defence Ministry or ODP was established in late 1975. It had 600,000 members, having personnel in virtually every village by 1979. It had both armed and unarmed units dispersed in villages throughout the country. The People\'s Vigilance Brigades (*Brigadas Populares de Vigilância, BPV*) also serve a similar purpose.
## Training establishments {#training_establishments}
### Armed Forces Academy {#armed_forces_academy}
The Military Academy (*Academia Militar do Exército, AMEx*) is a military university public higher education establishment whose mission is to train officers of the Permanent Staff of the Army. It has been in operation since 21 August 2009 by presidential decree. Its headquarters are in Lobito. It trains in the following specialties:
- Infantry
- Tanks
- Land Artillery
- Anti-Air Defense
- Military Engineering
- Logistics
- Telecommunications
- Hidden Direction of Troops
- Military Administration
- Armament and Technique
- Chemical Defense
- Operational Military Intelligence
- Technical Repair and Maintenance Platoon of Auto and Armored Technique
### Navy {#navy_1}
- Naval War Institute (INSG)
- Naval Academy
- Naval Specialist School
### Air Force {#air_force_1}
- Angolan Military Aviation School
- Pilot Basic Training School (Lobito)
## Institutions/other units {#institutionsother_units}
### Museum of the Armed Forces {#museum_of_the_armed_forces}
### Military Hospitals {#military_hospitals}
The Military hospital of the FAA is the Main Military Hospital. It has the following lineage:
- 1961 -- Evacuation Infirmary
- 1962 -- Military Hospital of Luanda
- 1975 -- Military Hospital
- 1976 -- Central Military Hospital
- 1989 -- Main Military Hospital
It provides specialized medical assistance in accordance with the military health system; It also promotes post-graduate education and scientific research. Currently, the Main Military Hospital serves 39 special medical specialties. It is a headed by a Director General whose main supporting body is the board of directors.
### Supreme Military Court {#supreme_military_court}
The Supreme Military Court is the highest organ of the hierarchy of military courts. The Presiding Judge, the Deputy Presiding Judge and the other Counselor Judges of the Supreme Military Court are appointed by the President of the Republic. The composition, organization, powers and functioning of the Supreme Military Court are established by law.
### Military Bands {#military_bands}
The FAA maintains Portuguese-style military bands in all three branches and in individual units. The primary band is the 100-member Music Band of the Presidential Security Household. The music band of the Army Command was created on 16 June 1994 and four years later, on 15 August 1998, the National Air Force created a music band within an artistic brigade. The navy has its own marching band, as well as a small musical group known as *Banda 10 de Julho* (10 July Band), based at the Luanda Naval Base.
## Foreign deployments {#foreign_deployments}
The FAPLA\'s main counterinsurgency effort was directed against UNITA in the southeast, and its conventional capabilities were demonstrated principally in the undeclared South African Border War. The FAPLA first performed its external assistance mission with the dispatch of 1,000 to 1,500 troops to São Tomé and Príncipe in 1977 to bolster the socialist regime of President Manuel Pinto da Costa. During the next several years, Angolan forces conducted joint exercises with their counterparts and exchanged technical operational visits. The Angolan expeditionary force was reduced to about 500 in early 1985.
The Angolan Armed Forces were controversially involved in training the armed forces of fellow Lusophone states Cape Verde and Guinea-Bissau. In the case of the latter, the 2012 Guinea-Bissau coup d\'état was cited by the coup leaders as due to Angola\'s involvement in trying to \"reform\" the military in connivance with the civilian leadership.
Occasionally skirmishes on the DRC-Angola border happening, sometimes also in connection with the Cabinda conflict. In 2020 one Angolan soldier died after a gun battle with congolese forces in Kasai region on DRC territory. A presence during the unrest in Ivory Coast, 2010--2011, were not officially confirmed. However, the *\[\[Frankfurter Allgemeine Zeitung\]\]*, citing *Jeune Afrique*, said that among President Gbagbo\'s guards were 92 personnel of President Dos Santos\'s Presidential Guard Unit. Angola is basically interested in the participation of the FAA operations of the African Union and has formed special units for this purpose.
In 2021, the Angolan Parliament approved integration of FAA into Southern African Development Community (SADC)\'s mission for peace in Cabo Delgado, Mozambique. Angola sent a team of 20 officers to participate.
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Foreign relations of Angola
|
The **foreign relations of Angola** are based on Angola\'s strong support of U.S. foreign policy as the Angolan economy is dependent on U.S. foreign aid. From 1975 to 1989, Angola was aligned with the Eastern bloc, in particular the Soviet Union, Libya, and Cuba. Since then, it has focused on improving relationships with Western countries, cultivating links with other Portuguese-speaking countries, and asserting its own national interests in Central Africa through military and diplomatic intervention. In 1993, it established formal diplomatic relations with the United States. It has entered the Southern African Development Community as a vehicle for improving ties with its largely Anglophone neighbors to the south. Zimbabwe and Namibia joined Angola in its military intervention in the Democratic Republic of the Congo, where Angolan troops remain in support of the Joseph Kabila government. It also has intervened in the Republic of the Congo (Brazzaville) in support of Denis Sassou-Nguesso in the civil war.
Since 1998, Angola has successfully worked with the United Nations Security Council to impose and carry out sanctions on UNITA. More recently, it has extended those efforts to controls on conflict diamonds, the primary source of revenue for UNITA during the Civil War that ended in 2002. At the same time, Angola has promoted the revival of the Community of Portuguese-Speaking Countries (CPLP) as a forum for cultural exchange and expanding ties with Portugal (its former ruler) and Brazil (which shares many cultural affinities with Angola) in particular. Angola is a member of the Port Management Association of Eastern and Southern Africa (PMAESA).
## Diplomatic relations {#diplomatic_relations}
List of countries which Angola maintains diplomatic relations with:
-----
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## Bilateral relations {#bilateral_relations}
### Africa
+---------+------------------------+---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| Country | Formal Relations Began | Notes |
+=========+========================+=================================================================================================================================================================================================================================================================================================================================================================================================================================================================================================================================================================================================================================================================================================================================================================================================================================+
| | 30 October 1977 | See Angola--Cape Verde relations |
| | | |
| | | Cape Verde signed a friendship accord with Angola in December 1975, shortly after Angola gained its independence. Cape Verde and Guinea-Bissau served as stop-over points for Cuban troops on their way to Angola to fight UNITA rebels and South African troops. Prime Minister Pedro Pires sent FARP soldiers to Angola where they served as the personal bodyguards of Angolan President José Eduardo dos Santos. |
| | | |
| | | - Angola has an embassy in Praia. |
| | | - Cape Verde has an embassy in Luanda and a consulate in Benguela. |
+---------+------------------------+---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| | 17 October 1978 | Many thousands of Angolans fled the country after the civil war. More than 20,000 people were forced to leave the Democratic Republic of the Congo in 2009, an action the DR Congo said was in retaliation for regular expulsion of Congolese diamond miners who were in Angola illegally. Angola sent a delegation to DR Congo\'s capital Kinshasa and succeeded in stopping government-forced expulsions which had become a \"tit-for-tat\" immigration dispute. \"Congo and Angola have agreed to suspend expulsions from both sides of the border,\" said Lambert Mende, DR Congo information minister, in October 2009. \"We never challenged the expulsions themselves; we challenged the way they were being conducted -- all the beating of people and looting their goods, even sometimes their clothes,\" Mende said. |
| | | |
| | | - Angola has an embassy in Kinshasa. |
| | | - DR Congo has an embassy in Luanda. |
+---------+------------------------+---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| | | See Angola--Kenya relations |
| | | |
| | | - Angola has an embassy in Nairobi. |
| | | - Kenya has an embassy in Luanda. |
+---------+------------------------+---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| | 5 July 1975 | See Angola--Mozambique relations |
| | | |
| | | - Angola has an embassy in Maputo. |
| | | - Mozambique has an embassy in Luanda. |
+---------+------------------------+---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| | 18 September 1990 | See Angola--Namibia relations |
| | | |
| | | Namibia borders Angola to the south. In 1999, Namibia signed a mutual defense pact with its northern neighbor Angola.{{cite web |
+---------+------------------------+---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| | 15 March 1976 | See Angola--Nigeria relations |
| | | |
| | | Angolan-Nigerian relations are primarily based on their roles as oil exporting nations. Both are members of the Organization of the Petroleum Exporting Countries, the African Union and other multilateral organizations. |
| | | |
| | | - Angola has an embassy in Abuja. |
| | | - Nigeria has an embassy in Luanda. |
+---------+------------------------+---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| | 17 May 1994 | See Angola--South Africa relations |
| | | |
| | | Angola-South Africa relations are quite strong as the ruling parties in both nations, the African National Congress in South Africa and the MPLA in Angola, fought together during the Angolan Civil War and South African Border War. They fought against UNITA rebels, based in Angola, and the apartheid-era government in South Africa who supported them. Nelson Mandela mediated between the MPLA and UNITA factions during the last years of Angola\'s civil war. |
| | | |
| | | - Angola has an embassy in Pretoria and consulates-general in Cape Town and Johannesburg. |
| | | - South Africa has an embassy in Luanda. |
+---------+------------------------+---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| | 15 October 1982 | See Angola--Zimbabwe relations |
+---------+------------------------+---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
### Americas
+---------+------------------------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| Country | Formal Relations Began | Notes |
+=========+========================+============================================================================================================================================================================================================================================================================================================================================================================================================================================================================+
| | 2 June 1979 | Both countries established diplomatic relations on 2 June 1979 See Angola--Argentina relations |
| | | |
| | | - Angola has an embassy in Buenos Aires. |
| | | - Argentina has an embassy in Luanda. |
+---------+------------------------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| | 12 November 1975 | See Angola--Brazil relations |
| | | |
| | | Commercial and economic ties dominate the relations of each country. Parts of both countries were part of the Portuguese Empire from the early 16th century until Brazil\'s independence in 1822. As of November 2007, \"trade between the two countries is booming as never before\" |
| | | |
| | | - Angola has an embassy in Brasília and consulates-general in Rio de Janeiro and São Paulo. |
| | | - Brazil has an embassy in Luanda. |
+---------+------------------------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| | 1 February 1978 | Both countries established diplomatic relations on 1 February 1978 |
| | | |
| | | Canada-Angola relations were established in 1978, and Canada is accredited to Angola from its embassy in Harare, Zimbabwe. Ties have grown since the end of the civil war in 2002, with increased engagement in areas of mutual interest. As Chair of the United Nations Security Council\'s Angola Sanctions Committee, Canada limited the ability of UNITA to continue its military campaign, sanctions helped to bring a ceasefire agreement to end Angola\'s conflict. |
| | | |
| | | - Angola is accredited to Canada from its embassy in Washington, D.C., United States. |
| | | - Canada is accredited to Angola from its embassy in Harare, Zimbabwe and maintains an honorary consulate in Luanda. |
+---------+------------------------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| | 15 November 1975 | See Angola--Cuba relations |
| | | |
| | | During Angola\'s civil war Cuban forces fought to install a Marxist--Leninist MPLA-PT government, against Western-backed UNITA and FLNA guerrillas and the South-African army. |
| | | |
| | | - Angola has an embassy in Havana. |
| | | - Cuba has an embassy in Luanda. |
+---------+------------------------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| | 20 February 1976 | Both countries established diplomatic relations on 20 February 1976 See Angola--Mexico relations |
| | | |
| | | - Angola is accredited to Mexico from its embassy in Washington, D.C., United States. |
| | | - Mexico is accredited to Angola from its embassy in Pretoria, South Africa and maintains an honorary consulate in Luanda. |
+---------+------------------------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| | 14 July 1994 | Both countries established diplomatic relations on 14 July 1994 See Angola--United States relations From the mid-1980s through at least 1992, the United States was the primary source of military and other support for the UNITA rebel movement, which was led from its creation through 2002 by Jonas Savimbi. The U.S. refused to recognize Angola diplomatically during this period. |
| | | |
| | | Relations between the United States of America and the Republic of Angola (formerly the People\'s Republic of Angola) have warmed since Angola\'s ideological renunciation of Communism before the 1992 elections. |
| | | |
| | | - Angola has an embassy in Washington, D.C., and consulates-general in Houston and New York City. |
| | | - United States has an embassy in Luanda. |
+---------+------------------------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| | 6 March 1987 | Both countries established diplomatic relations on 6 March 1987 See Angola--Uruguay relations |
| | | |
| | | - Angola has a consulate-general in Montevideo. |
| | | - Uruguay is accredited to Angola from its embassy in Pretoria, South Africa. |
+---------+------------------------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
### Asia
+---------+------------------------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| Country | Formal Relations Began | Notes |
+=========+========================+==================================================================================================================================================================================================================================================================================================================================================================================================================================================================================================================================================================================+
| | 12 January 1983 | Both countries established diplomatic relations on 12 January 1983 See Angola--China relations |
| | | |
| | | Chinese prime minister Wen Jiabao visited Angola in June 2006, offering a US\$9 billion loan for infrastructure improvements in return for petroleum. The PRC has invested heavily in Angola since the end of the civil war in 2002. João Manuel Bernardo, the current ambassador of Angola to China, visited the PRC in November 2007. |
| | | |
| | | - Angola has an embassy in Beijing and a consulate-general in Macau. |
| | | - China has an embassy in Luanda. |
+---------+------------------------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| | 2 June 1979 | Both countries established diplomatic relations on 2 June 1979 See Angola--India relations |
| | | |
| | | - Angola has an embassy in New Delhi. |
| | | - India has an embassy in Luanda. |
+---------+------------------------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| | 16 April 1992 | See Angola--Israel relations |
| | | |
| | | Angola-Israel relations, primarily based on trade and pro-United States foreign policies, are excellent. In March 2006, the trade volume between the two countries amounted to \$400 million. In 2005, President José Eduardo dos Santos visited Israel. |
| | | |
| | | - [Angola/Israel business volume amounted at USD 400 million](https://web.archive.org/web/20141225062707/http://www.angoladigital.net/negocios/index.php?Itemid=47&id=150&option=com_content&task=view) Angola Press, 22 March 2006 |
| | | - [Israeli Ambassador Highlights Relations With Angola](https://web.archive.org/web/20060517045254/http://www.angolapress-angop.ao/noticia-e.asp?ID=437778) Angola Press |
| | | - Angola has an embassy in Tel Aviv. |
| | | - Israel has an embassy in Luanda. |
+---------+------------------------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| | September 1976 | See Angola--Japan relations |
| | | |
| | | Diplomatic relations between Japan and Angola were established in September 1976. Japan has donated towards demining following the civil war. |
| | | |
| | | - Angola has an embassy in Tokyo. |
| | | - Japan has an embassy in Luanda. |
+---------+------------------------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| | 20 October 1977 | Both countries established diplomatic relations on 20 October 1977 |
| | | |
| | | The Government of Angola called for the support of Pakistan for the candidature of Angola to the seat of non-permanent member of the UN Security Council, whose election is set for September this year, during the 69th session of the General Assembly of United Nations. On the fringes of the ceremony, the Angolan diplomat also met with officials in charge of the economic and commercial policy of Pakistan, to assess the business opportunities between the two states. It asked to discuss aspects related to the cooperation on several domains of common interest. |
+---------+------------------------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| | 14 September 2001 | Both countries established diplomatic relations on 14 September 2001. |
| | | |
| | | - Angola has an embassy in Manila. |
| | | - Philippines is accredited to Angola from its embassy in Lisbon, Portugal. |
+---------+------------------------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| | 9 July 1980 | Both countries established diplomatic relations on 9 July 1980 See Angola--Turkey relations |
| | | |
| | | - Angola has an embassy in Ankara. |
| | | - Turkey has an embassy in Luanda. |
| | | - Trade volume between the two countries was US\$212 million in 2019. |
+---------+------------------------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| | 12 November 1975 | Both countries established diplomatic relations on 12 November 1975 See Angola--Vietnam relations |
| | | |
| | | Angola-Vietnam relations were established on 12 November 1975 after Angola gained its independence, when future president of Angola Agostinho Neto visited Vietnam. Angola and Vietnam have steadfast partners as both transitioned from Cold War-era foreign policies of international communism to pro-Western pragmatism following the fall of the Soviet Union. |
| | | |
| | | - Angola has an embassy in Hanoi. |
| | | - Vietnam has an embassy in Luanda. |
+---------+------------------------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
### Europe
+---------+------------------------+-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| Country | Formal Relations Began | Notes |
+=========+========================+=====================================================================================================================================================================================================================================================================================================================================================================================================================================================================================================+
| | 17 February 1976 | See Angola--France relations |
| | | |
| | | Relations between the two countries have not always been cordial due to the former French government\'s policy of supporting militant separatists in Angola\'s Cabinda province and the international Angolagate scandal embarrassed both governments by exposing corruption and illicit arms deals. Following French president Nicolas Sarkozy\'s visit in 2008, relations have improved. |
| | | |
| | | - Angola has an embassy in Paris. |
| | | - France has an embassy in Luanda. |
+---------+------------------------+-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| | 16 August 1979 | Both countries established diplomatic relations on 16 August 1979 See Angola--Germany relations |
| | | |
| | | - Angola has an embassy in Berlin. |
| | | - Germany has an embassy in Luanda. |
+---------+------------------------+-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| | 14 April 1975 | - Angola has an embassy to the Holy See based in Rome. |
| | | - Holy See has an Apostolic Nuncio to Angola. |
+---------+------------------------+-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| | 4 June 1976 | See Angola--Italy relations |
| | | |
| | | - Angola has an embassy in Rome. |
| | | - Italy has an embassy in Luanda. |
+---------+------------------------+-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| | 18 February 1976 | - Angola has an embassy in The Hague and a consulate-general in Rotterdam. |
| | | - Netherlands has an embassy in Luanda. |
+---------+------------------------+-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| | 9 March 1976 | See Angola--Portugal relations |
| | | |
| | | Angola-Portugal relations have significantly improved since the Angolan government abandoned communism and nominally embraced democracy in 1991, embracing a pro-U.S. and to a lesser degree pro-Europe foreign policy. Portugal ruled Angola for 400 years, colonizing the territory from 1483 until independence in 1975. Angola\'s war for independence did not end in a military victory for either side, but was suspended as a result of a coup in Portugal that replaced the Caetano regime. |
| | | |
| | | - Angola has an embassy in Lisbon and a consulate-general in Porto. |
| | | - Portugal has an embassy in Luanda and a consulate-general in Benguela. |
+---------+------------------------+-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| | 11 November 1975 | Both countries established diplomatic relations on 11 November 1975 See Angola--Russia relations |
| | | |
| | | - Angola has an embassy in Moscow. |
| | | - Russia has an embassy in Luanda. |
+---------+------------------------+-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| | 12 November 1975 | Both countries established diplomatic relations on 12 November 1975 See Angola--Serbia relations |
| | | |
| | | The defence minister of Serbia, Dragan Šutanovac, stated in a 2011 meeting in Luanda that Serbia would negotiate with the Angolan military authorities for the construction of a new military hospital in Angola. |
| | | |
| | | Angola supports Serbia\'s stance on Kosovo, and recognizes Serbia\'s territorial integrity. |
| | | |
| | | - Angola has an embassy in Belgrade. |
| | | - Serbia has an embassy in Luanda. |
+---------+------------------------+-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| | 19 October 1977 | Both countries established diplomatic relations on 19 October 1977 See Angola--Spain relations |
| | | |
| | | - Angola has an embassy in Madrid. |
| | | - Spain has an embassy in Luanda. |
+---------+------------------------+-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| | 14 October 1977 | Angola established diplomatic relations with the UK on 14 October 1977. |
| | | |
| | | - Angola maintains an embassy in London. |
| | | - The United Kingdom is accredited to Angola through its embassy in Luanda. |
| | | |
| | | Both countries share common membership of the Atlantic co-operation pact, and the World Trade Organization. |
+---------+------------------------+-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
### See also {#see_also}
- List of diplomatic missions in Angola
- List of diplomatic missions of Angola
- Visa requirements for Angolan citizens
| 2025-08-01T00:00:00 |
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Android (robot)
|
`{{Use dmy dates|date=July 2020}}`{=mediawiki} An **android** is a humanoid robot or other artificial being, often made from a flesh-like material. Historically, androids existed only in the domain of science fiction and were frequently seen in film and television, but advances in robot technology have allowed the design of functional and realistic humanoid robots.
## Terminology
The *Oxford English Dictionary* traces the earliest use (as \"Androides\") to Ephraim Chambers\' 1728 *Cyclopaedia,* in reference to an automaton that St. Albertus Magnus allegedly created. By the late 1700s, \"androides\", elaborate mechanical devices resembling humans performing human activities, were displayed in exhibit halls. The term \"android\" appears in US patents as early as 1863 in reference to miniature human-like toy automatons. The term *android* was used in a more modern sense by the French author Auguste Villiers de l\'Isle-Adam in his work *Tomorrow\'s Eve* (1886), featuring an artificial humanoid robot named Hadaly. The term made an impact into English pulp science fiction starting from Jack Williamson\'s *The Cometeers* (1936) and the distinction between mechanical robots and fleshy androids was popularized by Edmond Hamilton\'s Captain Future stories (1940--1944).
Although Karel Čapek\'s robots in *R.U.R. (Rossum\'s Universal Robots)* (1921)---the play that introduced the word *robot* to the world---were organic artificial humans, the word \"robot\" has come to primarily refer to mechanical humans, animals, and other beings. The term \"android\" can mean either one of these, while a cyborg (\"cybernetic organism\" or \"bionic man\") would be a creature that is a combination of organic and mechanical parts.
The term \"droid\", popularized by George Lucas in the original *Star Wars* film and now used widely within science fiction, originated as an abridgment of \"android\", but has been used by Lucas and others to mean any robot, including distinctly non-human form machines like R2-D2. The word \"android\" was used in *Star Trek: The Original Series* episode \"What Are Little Girls Made Of?\" The abbreviation \"andy\", coined as a pejorative by writer Philip K. Dick in his novel *Do Androids Dream of Electric Sheep?*, has seen some further usage, such as within the TV series *Total Recall 2070*.
While the term \"android\" is used in reference to human-looking robots in general (not necessarily male-looking humanoid robots), a robot with a female appearance can also be referred to as a *gynoid*. Besides one can refer to robots without alluding to their sexual appearance by calling them *anthrobots* (a portmanteau of anthrōpos and robot; see *anthrobotics*) or *anthropoids* (short for anthropoid robots; the term *humanoids* is not appropriate because it is already commonly used to refer to human-like organic species in the context of science fiction, futurism and speculative astrobiology).
Authors have used the term *android* in more diverse ways than *robot* or *cyborg*. In some fictional works, the difference between a robot and android is only superficial, with androids being made to look like humans on the outside but with robot-like internal mechanics. In other stories, authors have used the word \"android\" to mean a wholly organic, yet artificial, creation. Other fictional depictions of androids fall somewhere in between.
Eric G. Wilson, who defines an android as a \"synthetic human being\", distinguishes between three types of android, based on their body\'s composition:
- the mummy type -- made of \"dead things\" or \"stiff, inanimate, natural material\", such as mummies, puppets, dolls and statues
- the golem type -- made from flexible, possibly organic material, including golems and homunculi
- the automaton type -- made from a mix of dead and living parts, including automatons and robots
Although human morphology is not necessarily the ideal form for working robots, the fascination in developing robots that can mimic it can be found historically in the assimilation of two concepts: *simulacra* (devices that exhibit likeness) and *automata* (devices that have independence).
## Projects
Several projects aiming to create androids that look, and, to a certain degree, speak or act like a human being have been launched or are underway.
### Japan
Japanese robotics have been leading the field since the 1970s. Waseda University initiated the WABOT project in 1967, and in 1972 completed the WABOT-1, the first android, a full-scale humanoid intelligent robot. Its limb control system allowed it to walk with the lower limbs, and to grip and transport objects with hands, using tactile sensors. Its vision system allowed it to measure distances and directions to objects using external receptors, artificial eyes and ears. And its conversation system allowed it to communicate with a person in Japanese, with an artificial mouth.
In 1984, WABOT-2 was revealed, and made a number of improvements. It was capable of playing the organ. Wabot-2 had ten fingers and two feet, and was able to read a score of music. It was also able to accompany a person. In 1986, Honda began its humanoid research and development program, to create humanoid robots capable of interacting successfully with humans.
The Intelligent Robotics Lab, directed by Hiroshi Ishiguro at Osaka University, and the Kokoro company demonstrated the Actroid at Expo 2005 in Aichi Prefecture, Japan and released the Telenoid R1 in 2010. In 2006, Kokoro developed a new *DER 2* android. The height of the human body part of DER2 is 165 cm. There are 47 mobile points. DER2 can not only change its expression but also move its hands and feet and twist its body. The \"air servosystem\" which Kokoro developed originally is used for the actuator. As a result of having an actuator controlled precisely with air pressure via a servosystem, the movement is very fluid and there is very little noise. DER2 realized a slimmer body than that of the former version by using a smaller cylinder. Outwardly DER2 has a more beautiful proportion. Compared to the previous model, DER2 has thinner arms and a wider repertoire of expressions. Once programmed, it is able to choreograph its motions and gestures with its voice.
The Intelligent Mechatronics Lab, directed by Hiroshi Kobayashi at the Tokyo University of Science, has developed an android head called *Saya*, which was exhibited at Robodex 2002 in Yokohama, Japan. There are several other initiatives around the world involving humanoid research and development at this time, which will hopefully introduce a broader spectrum of realized technology in the near future. Now Saya is *working* at the Science University of Tokyo as a guide.
The Waseda University (Japan) and NTT docomo\'s manufacturers have succeeded in creating a shape-shifting robot *WD-2*. It is capable of changing its face. At first, the creators decided the positions of the necessary points to express the outline, eyes, nose, and so on of a certain person. The robot expresses its face by moving all points to the decided positions, they say. The first version of the robot was first developed back in 2003. After that, a year later, they made a couple of major improvements to the design. The robot features an elastic mask made from the average head dummy. It uses a driving system with a 3DOF unit. The WD-2 robot can change its facial features by activating specific facial points on a mask, with each point possessing three degrees of freedom. This one has 17 facial points, for a total of 56 degrees of freedom. As for the materials they used, the WD-2\'s mask is fabricated with a highly elastic material called Septom, with bits of steel wool mixed in for added strength. Other technical features reveal a shaft driven behind the mask at the desired facial point, driven by a DC motor with a simple pulley and a slide screw. Apparently, the researchers can also modify the shape of the mask based on actual human faces. To \"copy\" a face, they need only a 3D scanner to determine the locations of an individual\'s 17 facial points. After that, they are then driven into position using a laptop and 56 motor control boards. In addition, the researchers also mention that the shifting robot can even display an individual\'s hair style and skin color if a photo of their face is projected onto the 3D Mask.
### Singapore
Prof Nadia Thalmann, a Nanyang Technological University scientist, directed efforts of the Institute for Media Innovation along with the School of Computer Engineering in the development of a social robot, Nadine. Nadine is powered by software similar to Apple\'s Siri or Microsoft\'s Cortana. Nadine may become a personal assistant in offices and homes in future, or she may become a companion for the young and the elderly.
Assoc Prof Gerald Seet from the School of Mechanical & Aerospace Engineering and the BeingThere Centre led a three-year R&D development in tele-presence robotics, creating EDGAR. A remote user can control EDGAR with the user\'s face and expressions displayed on the robot\'s face in real time. The robot also mimics their upper body movements.
### South Korea {#south_korea}
KITECH researched and developed EveR-1, an android interpersonal communications model capable of emulating human emotional expression via facial \"musculature\" and capable of rudimentary conversation, having a vocabulary of around 400 words. She is `{{nowrap|160 cm}}`{=mediawiki} tall and weighs `{{nowrap|50 kg}}`{=mediawiki}, matching the average figure of a Korean woman in her twenties. EveR-1\'s name derives from the Biblical Eve, plus the letter *r* for *robot*. EveR-1\'s advanced computing processing power enables speech recognition and vocal synthesis, at the same time processing lip synchronization and visual recognition by 90-degree micro-CCD cameras with face recognition technology. An independent microchip inside her artificial brain handles gesture expression, body coordination, and emotion expression. Her whole body is made of highly advanced synthetic jelly silicon and with 60 artificial joints in her face, neck, and lower body; she is able to demonstrate realistic facial expressions and sing while simultaneously dancing. In South Korea, the Ministry of Information and Communication had an ambitious plan to put a robot in every household by 2020. Several robot cities have been planned for the country: the first will be built in 2016 at a cost of 500 billion won (US\$440 million), of which 50 billion is direct government investment. The new robot city will feature research and development centers for manufacturers and part suppliers, as well as exhibition halls and a stadium for robot competitions. The country\'s new Robotics Ethics Charter will establish ground rules and laws for human interaction with robots in the future, setting standards for robotics users and manufacturers, as well as guidelines on ethical standards to be programmed into robots to prevent human abuse of robots and vice versa.
### United States {#united_states}
Walt Disney and a staff of Imagineers created Great Moments with Mr. Lincoln that debuted at the 1964 New York World\'s Fair.
Dr. William Barry, an Education Futurist and former visiting West Point Professor of Philosophy and Ethical Reasoning at the United States Military Academy, created an AI android character named \"Maria Bot\". This Interface AI android was named after the infamous fictional robot Maria in the 1927 film *Metropolis*, as a well-behaved distant relative. Maria Bot is the first AI Android Teaching Assistant at the university level. Maria Bot has appeared as a keynote speaker as a duo with Barry for a TEDx talk in Everett, Washington in February 2020.
Resembling a human from the shoulders up, Maria Bot is a virtual being android that has complex facial expressions and head movement and engages in conversation about a variety of subjects. She uses AI to process and synthesize information to make her own decisions on how to talk and engage. She collects data through conversations, direct data inputs such as books or articles, and through internet sources.
Maria Bot was built by an international high-tech company for Barry to help improve education quality and eliminate education poverty. Maria Bot is designed to create new ways for students to engage and discuss ethical issues raised by the increasing presence of robots and artificial intelligence. Barry also uses Maria Bot to demonstrate that programming a robot with life-affirming, ethical framework makes them more likely to help humans to do the same.
Maria Bot is an ambassador robot for good and ethical AI technology.
Hanson Robotics, Inc., of Texas and KAIST produced an android portrait of Albert Einstein, using Hanson\'s facial android technology mounted on KAIST\'s life-size walking bipedal robot body. This Einstein android, also called \"Albert Hubo\", thus represents the first full-body walking android in history. Hanson Robotics, the FedEx Institute of Technology, and the University of Texas at Arlington also developed the android portrait of sci-fi author Philip K. Dick (creator of *Do Androids Dream of Electric Sheep?*, the basis for the film *Blade Runner*), with full conversational capabilities that incorporated thousands of pages of the author\'s works. In 2005, the PKD android won a first-place artificial intelligence award from AAAI.
### China
On April 19, 2025, 21 humanoid robots participated along with 12,000 human runners in a half-marathon in Beijing. While almost every robot fell down and had overheating problems, and the robots were continuously being controlled by human handlers accompanying them, six of the robots did reach the finish line. Two of them, Tiangong Ultra by Chinese robotics company UBTech, and N2 by Chinese company Noetix Robotics, which took first and second place respectively among robots in the race, stood out for their consistent (albeit slow) pace.
## Use in fiction {#use_in_fiction}
Androids are a staple of science fiction. Isaac Asimov pioneered the fictionalization of the science of robotics and artificial intelligence, notably in his 1950s series *I, Robot*. One thing common to most fictional androids is that the real-life technological challenges associated with creating thoroughly human-like robots --- such as the creation of strong artificial intelligence---are assumed to have been solved. Fictional androids are often depicted as mentally and physically equal or superior to humans---moving, thinking and speaking as fluidly as them.
The tension between the nonhuman substance and the human appearance---or even human ambitions---of androids is the dramatic impetus behind most of their fictional depictions. Some android heroes seek, like Pinocchio, to become human, as in the film *Bicentennial Man*, or Data in *Star Trek: The Next Generation*. Others, as in the film *Westworld*, rebel against abuse by careless humans. Android hunter Deckard in *Do Androids Dream of Electric Sheep?* and its film adaptation *Blade Runner* discovers that his targets appear to be, in some ways, more \"human\" than he is. The sequel *Blade Runner 2049* involves android hunter K, himself an android, discovering the same thing. Android stories, therefore, are not essentially stories \"about\" androids; they are stories about the human condition and what it means to be human.
One aspect of writing about the meaning of humanity is to use discrimination against androids as a mechanism for exploring racism in society, as in *Blade Runner*. Perhaps the clearest example of this is John Brunner\'s 1968 novel *Into the Slave Nebula*, where the blue-skinned android slaves are explicitly shown to be fully human. More recently, the androids Bishop and Annalee Call in the films *Aliens* and *Alien Resurrection* are used as vehicles for exploring how humans deal with the presence of an \"Other\". The 2018 video game *Detroit: Become Human* also explores how androids are treated as second class citizens in a near future society.
Female androids, or \"gynoids\", are often seen in science fiction, and can be viewed as a continuation of the long tradition of men attempting to create the stereotypical \"perfect woman\". Examples include the Greek myth of *Pygmalion* and the female robot Maria in Fritz Lang\'s *Metropolis*. Some gynoids, like Pris in *Blade Runner*, are designed as sex-objects, with the intent of \"pleasing men\'s violent sexual desires\", or as submissive, servile companions, such as in *The Stepford Wives*. Fiction about gynoids has therefore been described as reinforcing \"essentialist ideas of femininity\", although others have suggested that the treatment of androids is a way of exploring racism and misogyny in society.
The 2015 Japanese film *Sayonara*, starring Geminoid F, was promoted as \"the first movie to feature an android performing opposite a human actor\".
The 2023 Dutch film *I\'m Not a Robot* won the Academy Award for Best Live Action Short Film in 2025.
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List of anthropologists
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Algorithms (journal)
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***Algorithms*** is a monthly peer-reviewed open-access scientific journal of mathematics, covering design, analysis, and experiments on algorithms. The journal is published by MDPI and was established in 2008. The founding editor-in-chief was Kazuo Iwama (Kyoto University). From May 2014 to September 2019, the editor-in-chief was Henning Fernau (Universität Trier). The current editor-in-chief is Frank Werner (Otto-von-Guericke-Universität Magdeburg).
## Abstracting and indexing {#abstracting_and_indexing}
According to the *Journal Citation Reports*, the journal has a 2022 impact factor of 2.3. The journal is abstracted and indexed in: `{{columns-list|colwidth=30em|
*[[Chemical Abstracts Service]]<ref name=CASSI>{{cite web |url=http://cassi.cas.org/search.jsp |title=CAS Source Index |publisher=[[American Chemical Society]] |work=[[Chemical Abstracts Service]] |access-date=30 July 2018 |archive-url=https://wayback.archive-it.org/all/20100211180645/http://cassi.cas.org/ |archive-date=11 February 2010 |url-status=dead |df=dmy-all }}</ref>
*[[Ei Compendex]]<ref name=Compendex>{{cite web |url=http://www.elsevier.com/online-tools/engineering-village/contentdatabase-overview |title=Content/Database Overview - Compendex Source List |publisher=[[Elsevier]] |work=Engineering Village |access-date=30 July 2018}}</ref>
*[[Emerging Sources Citation Index]]<ref name=ISI>{{cite web |url=http://mjl.clarivate.com/ |title=Master Journal List |publisher=[[Clarivate Analytics]] |work=Intellectual Property & Science |access-date=30 July 2018}}</ref>
*[[Inspec]]<ref name=Inspec>{{cite web |url=http://www.theiet.org/resources/inspec/support/docs/loj.cfm?type=pdf |title=Inspec list of journals |publisher=[[Institution of Engineering and Technology (professional society)|Institution of Engineering and Technology]] |work=Inspec |access-date=30 July 2018}}</ref>
*[[MathSciNet]]
*[[Scopus]]<ref name=Scopus>{{cite web |url=https://www.scopus.com/sourceid/21100199795 |title=Source details: Algorithms |publisher=[[Elsevier]] |work=Scopus preview |access-date=30 July 2018}}</ref>
*[[zbMATH Open]] (2008–2019).<ref name=MATH>{{cite web |url=https://zbmath.org/serials/6757 |title=Algorithms|publisher=[[Springer Science+Business Media]] |work=[[zbMATH Open]] |access-date=13 September 2023}}</ref>
}}`{=mediawiki}
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Art
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thumb\|upright=1.5\|Visual artworks: (clockwise from upper left) an 1887 self-portrait by Vincent van Gogh; a female ancestor figure by a Chokwe artist; detail from *The Birth of Venus* (`{{c.|1484|lk=no}}`{=mediawiki}--1486) by Sandro Botticelli; and an Okinawan Shisa lion **Art** is a diverse range of cultural activity centered around *works* utilizing creative or imaginative talents, which are expected to evoke a worthwhile experience, generally through an expression of emotional power, conceptual ideas, technical proficiency, or beauty.
There is no generally agreed definition of what constitutes *art*, and its interpretation has varied greatly throughout history and across cultures. In the Western tradition, the three classical branches of visual art are painting, sculpture, and architecture. Theatre, dance, and other performing arts, as well as literature, music, film and other media such as interactive media, are included in a broader definition of \"the arts\". Until the 17th century, *art* referred to any skill or mastery and was not differentiated from crafts or sciences. In modern usage after the 17th century, where aesthetic considerations are paramount, the fine arts are separated and distinguished from acquired skills in general, such as the decorative or applied arts.
The nature of art and related concepts, such as creativity and interpretation, are explored in a branch of philosophy known as aesthetics. The resulting artworks are studied in the professional fields of art criticism and the history of art.
## Overview
In the perspective of the history of art, artistic works have existed for almost as long as humankind: from early prehistoric art to contemporary art; however, some theorists think that the typical concept of \"artistic works\" does not fit well outside modern Western societies. One early sense of the definition of *art* is closely related to the older Latin meaning, which roughly translates to \"skill\" or \"craft\", as associated with words such as \"artisan\". English words derived from this meaning include *artifact*, *artificial*, *artifice*, *medical arts*, and *military arts*. However, there are many other colloquial uses of the word, all with some relation to its etymology.
Over time, philosophers like Plato, Aristotle, Socrates and Immanuel Kant, among others, questioned the meaning of art. Several dialogues in Plato tackle questions about art, while Socrates says that poetry is inspired by the muses and is not rational. He speaks approvingly of this, and other forms of divine madness (drunkenness, eroticism, and dreaming) in the *Phaedrus*(265a--c), and yet in the **Republic** wants to outlaw Homer\'s great poetic art, and laughter as well. In *Ion*, Socrates gives no hint of the disapproval of Homer that he expresses in the *Republic*. The dialogue *Ion* suggests that Homer\'s *Iliad* functioned in the ancient Greek world as the Bible does today in the modern Christian world: as divinely inspired literary art that can provide moral guidance, if only it can be properly interpreted.
With regards to the literary art and the musical arts, Aristotle considered epic poetry, tragedy, comedy, Dithyrambic poetry and music to be mimetic or imitative art, each varying in imitation by medium, object, and manner. For example, music imitates with the media of rhythm and harmony, whereas dance imitates with rhythm alone, and poetry with language. The forms also differ in their object of imitation. Comedy, for instance, is a dramatic imitation of men worse than average; whereas tragedy imitates men slightly better than average. Lastly, the forms differ in their manner of imitation---through narrative or character, through change or no change, and through drama or no drama. Aristotle believed that imitation is natural to mankind and constitutes one of mankind\'s advantages over animals.
The more recent and specific sense of the word *art* as an abbreviation for *creative art* or *fine art* emerged in the early 17th century. Fine art refers to a skill used to express the artist\'s creativity, or to engage the audience\'s aesthetic sensibilities, or to draw the audience towards consideration of more refined or *finer* works of art.
Within this latter sense, the word *art* may refer to several things: (i) a study of a creative skill, (ii) a process of using the creative skill, (iii) a product of the creative skill, or (iv) the audience\'s experience with the creative skill. The creative arts (*art* as discipline) are a collection of disciplines which produce *artworks* (*art* as objects) that are compelled by a personal drive (art as activity) and convey a message, mood, or symbolism for the perceiver to interpret (art as experience). Art is something that stimulates an individual\'s thoughts, emotions, beliefs, or ideas through the senses. Works of art can be explicitly made for this purpose or interpreted on the basis of images or objects. For some scholars, such as Kant, the sciences and the arts could be distinguished by taking science as representing the domain of knowledge and the arts as representing the domain of the freedom of artistic expression.
Often, if the skill is being used in a common or practical way, people will consider it a craft instead of art. Likewise, if the skill is being used in a commercial or industrial way, it may be considered commercial art instead of fine art. On the other hand, crafts and design are sometimes considered applied art. Some art followers have argued that the difference between fine art and applied art has more to do with value judgments made about the art than any clear definitional difference. However, even fine art often has goals beyond pure creativity and self-expression. The purpose of works of art may be to communicate ideas, such as in politically, spiritually, or philosophically motivated art; to create a sense of beauty (see aesthetics); to explore the nature of perception; for pleasure; or to generate strong emotions. The purpose may also be seemingly nonexistent.
The nature of art has been described by philosopher Richard Wollheim as \"one of the most elusive of the traditional problems of human culture\". Art has been defined as a vehicle for the expression or communication of emotions and ideas, a means for exploring and appreciating formal elements for their own sake, and as *mimesis* or representation. Art as mimesis has deep roots in the philosophy of Aristotle. Leo Tolstoy identified art as a use of indirect means to communicate from one person to another. Benedetto Croce and R. G. Collingwood advanced the idealist view that art expresses emotions, and that the work of art therefore essentially exists in the mind of the creator. The theory of art as form has its roots in the philosophy of Kant, and was developed in the early 20th century by Roger Fry and Clive Bell. More recently, thinkers influenced by Martin Heidegger have interpreted art as the means by which a community develops for itself a medium for self-expression and interpretation. George Dickie has offered an institutional theory of art that defines a work of art as any artifact upon which a qualified person or persons acting on behalf of the social institution commonly referred to as \"the art world\" has conferred \"the status of candidate for appreciation\". Larry Shiner has described fine art as \"not an essence or a fate but something we have made. Art as we have generally understood it is a European invention barely two hundred years old.\"
Art may be characterized in terms of mimesis (its representation of reality), narrative (storytelling), expression, communication of emotion, or other qualities. During the Romantic period, art came to be seen as \"a special faculty of the human mind to be classified with religion and science\".
## History
thumb\|left\|upright=.8\|**\[\[Löwenmensch\]\]* figurine*, Germany, between 35,000 and 41,000 years old. One of the oldest-known examples of an artistic representation and the oldest confirmed statue ever discovered.
A shell engraved by *Homo erectus* was determined to be between 430,000 and 540,000 years old. A set of eight 130,000 years old white-tailed eagle talons bear cut marks and abrasion that indicate manipulation by neanderthals, possibly for using it as jewelry. A series of tiny, drilled snail shells about 75,000 years old---were discovered in a South African cave. Containers that may have been used to hold paints have been found dating as far back as 100,000 years.
The oldest piece of art found in Europe is the Riesenhirschknochen der Einhornhöhle, dating back 51,000 years and made by Neanderthals.
Sculptures, cave paintings, rock paintings and petroglyphs from the Upper Paleolithic dating to roughly 40,000 years ago have been found, but the precise meaning of such art is often disputed because so little is known about the cultures that produced them.
The first undisputed sculptures and similar art pieces, like the Venus of Hohle Fels, are the numerous objects found at the Caves and Ice Age Art in the Swabian Jura UNESCO World Heritage Site, where the oldest non-stationary works of human art yet discovered were found, in the form of carved animal and humanoid figurines, in addition to the oldest musical instruments unearthed so far, with the artifacts dating between 43,000 and 35,000 BC, so being the first centre of human art.
Many great traditions in art have a foundation in the art of one of the great ancient civilizations: Ancient Egypt, Mesopotamia, Persia, India, China, Ancient Greece, Rome, as well as Inca, Maya, and Olmec. Each of these centers of early civilization developed a unique and characteristic style in its art. Because of the size and duration of these civilizations, more of their art works have survived and more of their influence has been transmitted to other cultures and later times. Some also have provided the first records of how artists worked. For example, this period of Greek art saw a veneration of the human physical form and the development of equivalent skills to show musculature, poise, beauty, and anatomically correct proportions.
In Byzantine and Medieval art of the Western Middle Ages, much art focused on the expression of subjects about biblical and religious culture, and used styles that showed the higher glory of a heavenly world, such as the use of gold in the background of paintings, or glass in mosaics or windows, which also presented figures in idealized, patterned (flat) forms. Nevertheless, a classical realist tradition persisted in small Byzantine works, and realism steadily grew in the art of Catholic Europe.
Renaissance art had a greatly increased emphasis on the realistic depiction of the material world, and the place of humans in it, reflected in the corporeality of the human body, and development of a systematic method of graphical perspective to depict recession in a three-dimensional picture space.
In the east, Islamic art\'s rejection of iconography led to emphasis on geometric patterns, calligraphy, and architecture. Further east, religion dominated artistic styles and forms too. India and Tibet saw emphasis on painted sculptures and dance, while religious painting borrowed many conventions from sculpture and tended to bright contrasting colors with emphasis on outlines. China saw the flourishing of many art forms: jade carving, bronzework, pottery (including the stunning Terracotta Army of Emperor Qin), poetry, calligraphy, music, painting, drama, fiction, etc. Chinese styles vary greatly from era to era and each one is traditionally named after the ruling dynasty. So, for example, Tang dynasty paintings are monochromatic and sparse, emphasizing idealized landscapes, but Ming dynasty paintings are busy and colorful, and focus on telling stories via setting and composition. Japan names its styles after imperial dynasties too, and also saw much interplay between the styles of calligraphy and painting. Woodblock printing became important in Japan after the 17th century.
The western Age of Enlightenment in the 18th century saw artistic depictions of physical and rational certainties of the clockwork universe, as well as politically revolutionary visions of a post-monarchist world, such as Blake\'s portrayal of Newton as a divine geometer, or David\'s propagandistic paintings. This led to Romantic rejections of this in favor of pictures of the emotional side and individuality of humans, exemplified in the novels of Goethe. The late 19th century then saw a host of artistic movements, such as academic art, Symbolism, impressionism and fauvism among others.
The history of 20th-century art is a narrative of endless possibilities and the search for new standards, each being torn down in succession by the next. Thus the parameters of Impressionism, Expressionism, Fauvism, Cubism, Dadaism, Surrealism, etc. cannot be maintained very much beyond the time of their invention. Increasing global interaction during this time saw an equivalent influence of other cultures into Western art. Thus, Japanese woodblock prints (themselves influenced by Western Renaissance draftsmanship) had an immense influence on impressionism and subsequent development. Later, African sculptures were taken up by Picasso and to some extent by Matisse. Similarly, in the 19th and 20th centuries the West has had huge impacts on Eastern art with originally western ideas like Communism and Post-Modernism exerting a powerful influence.
Modernism, the idealistic search for truth, gave way in the latter half of the 20th century to a realization of its unattainability. Theodor W. Adorno said in 1970, \"It is now taken for granted that nothing which concerns art can be taken for granted any more: neither art itself, nor art in relationship to the whole, nor even the right of art to exist.\" Relativism was accepted as an unavoidable truth, which led to the period of contemporary art and postmodern criticism, where cultures of the world and of history are seen as changing forms, which can be appreciated and drawn from only with skepticism and irony. Furthermore, the separation of cultures is increasingly blurred and some argue it is now more appropriate to think in terms of a global culture, rather than of regional ones.
In *The Origin of the Work of Art*, Martin Heidegger, a German philosopher and seminal thinker, describes the essence of art in terms of the concepts of being and truth. He argues that art is not only a way of expressing the element of truth in a culture, but the means of creating it and providing a springboard from which \"that which is\" can be revealed. Works of art are not merely representations of the way things are, but actually produce a community\'s shared understanding. Each time a new artwork is added to any culture, the meaning of what it is to exist is inherently changed.
Historically, art and artistic skills and ideas have often been spread through trade. An example of this is the Silk Road, where Hellenistic, Iranian, Indian and Chinese influences could mix. Greco Buddhist art is one of the most vivid examples of this interaction. The meeting of different cultures and worldviews also influenced artistic creation. An example of this is the multicultural port metropolis of Trieste at the beginning of the 20th century, where James Joyce met writers from Central Europe and the artistic development of New York City as a cultural melting pot.
## Forms, genres, media, and styles {#forms_genres_media_and_styles}
*Main article: The arts* The creative arts are often divided into more specific categories, typically along perceptually distinguishable categories such as media, genre, styles, and form. *Art form* refers to the elements of art that are independent of its interpretation or significance. It covers the methods adopted by the artist and the physical composition of the artwork, primarily non-semantic aspects of the work (i.e., figurae), such as color, contour, dimension, medium, melody, space, texture, and value. Form may also include Design principles, such as arrangement, balance, contrast, emphasis, harmony, proportion, proximity, and rhythm.
In general there are three schools of philosophy regarding art, focusing respectively on form, content, and context. Extreme Formalism is the view that all aesthetic properties of art are formal (that is, part of the art form). Philosophers almost universally reject this view and hold that the properties and aesthetics of art extend beyond materials, techniques, and form. Unfortunately, there is little consensus on terminology for these informal properties. Some authors refer to subject matter and content---i.e., denotations and connotations---while others prefer terms like meaning and significance.
Extreme Intentionalism holds that authorial intent plays a decisive role in the meaning of a work of art, conveying the content or essential main idea, while all other interpretations can be discarded. It defines the subject as the persons or idea represented, and the content as the artist\'s experience of that subject. For example, the composition of *Napoleon I on his Imperial Throne* is partly borrowed from the Statue of Zeus at Olympia. As evidenced by the title, the subject is Napoleon, and the content is Ingres\'s representation of Napoleon as \"Emperor-God beyond time and space\". Similarly to extreme formalism, philosophers typically reject extreme intentionalism, because art may have multiple ambiguous meanings and authorial intent may be unknowable and thus irrelevant. Its restrictive interpretation is \"socially unhealthy, philosophically unreal, and politically unwise\".
Finally, the developing theory of post-structuralism studies art\'s significance in a cultural context, such as the ideas, emotions, and reactions prompted by a work. The cultural context often reduces to the artist\'s techniques and intentions, in which case analysis proceeds along lines similar to formalism and intentionalism. However, in other cases historical and material conditions may predominate, such as religious and philosophical convictions, sociopolitical and economic structures, or even climate and geography. Art criticism continues to grow and develop alongside art.
### Skill and craft {#skill_and_craft}
Art can connote a sense of trained ability or mastery of a medium. Art can also refer to the developed and efficient use of a language to convey meaning with immediacy or depth. Art can be defined as an act of expressing feelings, thoughts, and observations.
There is an understanding that is reached with the material as a result of handling it, which facilitates one\'s thought processes. A common view is that the epithet *art*, particular in its elevated sense, requires a certain level of creative expertise by the artist, whether this be a demonstration of technical ability, an originality in stylistic approach, or a combination of these two. Traditionally skill of execution was viewed as a quality inseparable from art and thus necessary for its success; for Leonardo da Vinci, art, neither more nor less than his other endeavors, was a manifestation of skill. Rembrandt\'s work, now praised for its ephemeral virtues, was most admired by his contemporaries for its virtuosity. At the turn of the 20th century, the adroit performances of John Singer Sargent were alternately admired and viewed with skepticism for their manual fluency, yet at nearly the same time the artist who would become the era\'s most recognized and peripatetic iconoclast, Pablo Picasso, was completing a traditional academic training at which he excelled.
A common contemporary criticism of some modern art occurs along the lines of objecting to the apparent lack of skill or ability required in the production of the artistic object. In conceptual art, Marcel Duchamp\'s *Fountain* is among the first examples of pieces wherein the artist used found objects (\"ready-made\") and exercised no traditionally recognised set of skills. Tracey Emin\'s *My Bed*, or Damien Hirst\'s *The Physical Impossibility of Death in the Mind of Someone Living* follow this example. Emin slept (and engaged in other activities) in her bed before placing the result in a gallery as work of art. Hirst came up with the conceptual design for the artwork but has left most of the eventual creation of many works to employed artisans. Hirst\'s celebrity is founded entirely on his ability to produce shocking concepts. The actual production in many conceptual and contemporary works of art is a matter of assembly of found objects. However, there are many modernist and contemporary artists who continue to excel in the skills of drawing and painting and in creating *hands-on* works of art.
## Purpose
Art has had a great number of different functions throughout its history, making its purpose difficult to abstract or quantify to any single concept. This does not imply that the purpose of art is \"vague\", but that it has had many unique, different reasons for being created. Some of these functions of art are provided in the following outline. The different purposes of art may be grouped according to those that are non-motivated, and those that are motivated (Lévi-Strauss).
### Non-motivated functions {#non_motivated_functions}
The non-motivated purposes of art are those that are integral to being human, transcend the individual, or do not fulfill a specific external purpose. In this sense, Art, as creativity, is something humans must do by their very nature (i.e., no other species creates art), and is therefore beyond utility.
1. **Basic human instinct for harmony, balance, rhythm.** Art at this level is not an action or an object, but an internal appreciation of balance and harmony (beauty), and therefore an aspect of being human beyond utility.
> Imitation, then, is one instinct of our nature. Next, there is the instinct for \'harmony\' and rhythm, meters being manifestly sections of rhythm. Persons, therefore, starting with this natural gift developed by degrees their special aptitudes, till their rude improvisations gave birth to Poetry. -- Aristotle
2. **Experience of the mysterious.** Art provides a way to experience one\'s self in relation to the universe. This experience may often come unmotivated, as one appreciates art, music or poetry.
> The most beautiful thing we can experience is the mysterious. It is the source of all true art and science. -- Albert Einstein
3. **Expression of the imagination.** Art provides a means to express the imagination in non-grammatic ways that are not tied to the formality of spoken or written language. Unlike words, which come in sequences and each of which have a definite meaning, art provides a range of forms, symbols and ideas with meanings that are malleable.
> Jupiter\'s eagle \[as an example of art\] is not, like logical (aesthetic) attributes of an object, the concept of the sublimity and majesty of creation, but rather something else---something that gives the imagination an incentive to spread its flight over a whole host of kindred representations that provoke more thought than admits of expression in a concept determined by words. They furnish an aesthetic idea, which serves the above rational idea as a substitute for logical presentation, but with the proper function, however, of animating the mind by opening out for it a prospect into a field of kindred representations stretching beyond its ken. -- Immanuel Kant
4. **Ritualistic and symbolic functions.** In many cultures, art is used in rituals, performances and dances as a decoration or symbol. While these often have no specific utilitarian (motivated) purpose, anthropologists know that they often serve a purpose at the level of meaning within a particular culture. This meaning is not furnished by any one individual, but is often the result of many generations of change, and of a cosmological relationship within the culture.
> Most scholars who deal with rock paintings or objects recovered from prehistoric contexts that cannot be explained in utilitarian terms and are thus categorized as decorative, ritual or symbolic, are aware of the trap posed by the term \'art\'. -- Silva Tomaskova
### Motivated functions {#motivated_functions}
Motivated purposes of art refer to intentional, conscious actions on the part of the artists or creator. These may be to bring about political change, to comment on an aspect of society, to convey a specific emotion or mood, to address personal psychology, to illustrate another discipline, to (with commercial arts) sell a product, or used as a form of communication.
1. **Communication.** Art, at its simplest, is a form of communication. As most forms of communication have an intent or goal directed toward another individual, this is a motivated purpose. Illustrative arts, such as scientific illustration, are a form of art as communication. Maps are another example. However, the content need not be scientific. Emotions, moods and feelings are also communicated through art.
> \[Art is a set of\] artefacts or images with symbolic meanings as a means of communication. -- Steve Mithen
2. **Art as entertainment**. Art may seek to bring about a particular emotion or mood, for the purpose of relaxing or entertaining the viewer. This is often the function of the art industries of motion pictures and video games.
3. **The Avant-Garde. Art for political change.** One of the defining functions of early 20th-century art has been to use visual images to bring about political change. Art movements that had this goal---Dadaism, Surrealism, Russian constructivism, and Abstract Expressionism, among others---are collectively referred to as the *avant-garde* arts.
> By contrast, the realistic attitude, inspired by positivism, from Saint Thomas Aquinas to Anatole France, clearly seems to me to be hostile to any intellectual or moral advancement. I loathe it, for it is made up of mediocrity, hate, and dull conceit. It is this attitude which today gives birth to these ridiculous books, these insulting plays. It constantly feeds on and derives strength from the newspapers and stultifies both science and art by assiduously flattering the lowest of tastes; clarity bordering on stupidity, a dog\'s life. -- André Breton (Surrealism)
4. **Art as a \"free zone\"**, removed from the action of the social censure. Unlike the avant-garde movements, which wanted to erase cultural differences in order to produce new universal values, contemporary art has enhanced its tolerance towards cultural differences as well as its critical and liberating functions (social inquiry, activism, subversion, deconstruction, etc.), becoming a more open place for research and experimentation.
5. **Art for social inquiry, subversion or anarchy.** While similar to art for political change, subversive or deconstructivist art may seek to question aspects of society without any specific political goal. In this case, the function of art may be used to criticize some aspect of society. Graffiti art and other types of street art are graphics and images that are spray-painted or stencilled on publicly viewable walls, buildings, buses, trains, and bridges, usually without permission. Certain art forms, such as graffiti, may also be illegal when they break laws (in this case vandalism).
6. **Art for social causes.** Art can be used to raise awareness for a large variety of causes. A number of art activities were aimed at raising awareness of autism, cancer, human trafficking, and a variety of other topics, such as ocean conservation, human rights in Darfur, murdered and missing Aboriginal women, elder abuse, and pollution. Trashion, using trash to make fashion, practiced by artists such as Marina DeBris is one example of using art to raise awareness about pollution.
7. **Art for psychological and healing purposes.** Art is also used by art therapists, psychotherapists and clinical psychologists as art therapy. The Diagnostic Drawing Series, for example, is used to determine the personality and emotional functioning of a patient. The end product is not the principal goal in this case, but rather a process of healing, through creative acts, is sought. The resultant piece of artwork may also offer insight into the troubles experienced by the subject and may suggest suitable approaches to be used in more conventional forms of psychiatric therapy.
8. **Art for propaganda, or commercialism.** Art is often used as a form of propaganda, and thus can be used to subtly influence popular conceptions or mood. In a similar way, art that tries to sell a product also influences mood and emotion. In both cases, the purpose of art here is to subtly manipulate the viewer into a particular emotional or psychological response toward a particular idea or object.
9. **Art as a fitness indicator.** It has been argued that the ability of the human brain by far exceeds what was needed for survival in the ancestral environment. One evolutionary psychology explanation for this is that the human brain and associated traits (such as artistic ability and creativity) are the human equivalent of the peacock\'s tail. The purpose of the male peacock\'s extravagant tail has been argued to be to attract females (see also Fisherian runaway and handicap principle). According to this theory superior execution of art was evolutionarily important because it attracted mates.
The functions of art described above are not mutually exclusive, as many of them may overlap. For example, art for the purpose of entertainment may also seek to sell a product, i.e. the movie or video game.
## Steps
Art can be divided into any number of steps one can make an argument for. This section divides the creative process into broad three steps, but there is no consensus on an exact number.
### Preparation
In the first step, the artist envisions the art in their mind. By imagining what their art would look like, the artist begins the process of bringing the art into existence. Preparation of art may involve approaching and researching the subject matter. Artistic inspiration is one of the main drivers of art, and may be considered to stem from instinct, impressions, and feelings.
### Creation
In the second step, the artist executes the creation of their work. The creation of a piece can be affected by factors such as the artist\'s mood, surroundings, and mental state. For example, *The Black Paintings* by Francisco de Goya, created in the elder years of his life, are thought to be so bleak because he was in isolation and because of his experience with war. He painted them directly on the walls of his apartment in Spain, and most likely never discussed them with anyone. The Beatles stated drugs such as LSD and cannabis influenced some of their greatest hits, such as *Revolver.* Trial and error are considered an integral part of the creation process.
### Appreciation
The last step is art appreciation, which has the sub-topic of critique. In one study, over half of visual arts students agreed that reflection is an essential step of the art process. According to education journals, the reflection of art is considered an essential part of the experience. However an important aspect of art is that others may view and appreciate it as well. While many focus on whether those viewing/listening/etc. believe the art to be good/successful or not, art has profound value beyond its commercial success as a provider of information and health in society. Art enjoyment can bring about a wide spectrum of emotion due to beauty. Some art is meant to be practical, with its analysis studious, meant to stimulate discourse.
## Public access {#public_access}
Since ancient times, much of the finest art has represented a deliberate display of wealth or power, often achieved by using massive scale and expensive materials. Much art has been commissioned by political rulers or religious establishments, with more modest versions only available to the most wealthy in society.
Nevertheless, there have been many periods where art of very high quality was available, in terms of ownership, across large parts of society, above all in cheap media such as pottery, which persists in the ground, and perishable media such as textiles and wood. In many different cultures, the ceramics of indigenous peoples of the Americas are found in such a wide range of graves that they were clearly not restricted to a social elite, though other forms of art may have been. Reproductive methods such as moulds made mass-production easier, and were used to bring high-quality Ancient Roman pottery and Greek Tanagra figurines to a very wide market. Cylinder seals were both artistic and practical, and very widely used by what can be loosely called the middle class in the Ancient Near East. Once coins were widely used, these also became an art form that reached the widest range of society.
Another important innovation came in the 15th century in Europe, when printmaking began with small woodcuts, mostly religious, that were often very small and hand-colored, and affordable even by peasants who glued them to the walls of their homes. Printed books were initially very expensive, but fell steadily in price until by the 19th century even the poorest could afford some with printed illustrations. Popular prints of many different sorts have decorated homes and other places for centuries.
In 1661, the city of Basel, in Switzerland, opened the first public museum of art in the world, the Kunstmuseum Basel. Today, its collection is distinguished by an impressively wide historic span, from the early 15th century up to the immediate present. Its various areas of emphasis give it international standing as one of the most significant museums of its kind. These encompass: paintings and drawings by artists active in the Upper Rhine region between 1400 and 1600, and on the art of the 19th to 21st centuries.
Public buildings and monuments, secular and religious, by their nature normally address the whole of society, and visitors as viewers, and display to the general public has long been an important factor in their design. Egyptian temples are typical in that the most largest and most lavish decoration was placed on the parts that could be seen by the general public, rather than the areas seen only by the priests. Many areas of royal palaces, castles and the houses of the social elite were often generally accessible, and large parts of the art collections of such people could often be seen, either by anybody, or by those able to pay a small price, or those wearing the correct clothes, regardless of who they were, as at the Palace of Versailles, where the appropriate extra accessories (silver shoe buckles and a sword) could be hired from shops outside.
Special arrangements were made to allow the public to see many royal or private collections placed in galleries, as with the Orleans Collection mostly housed in a wing of the Palais Royal in Paris, which could be visited for most of the 18th century. In Italy the art tourism of the Grand Tour became a major industry from the Renaissance onwards, and governments and cities made efforts to make their key works accessible. The British Royal Collection remains distinct, but large donations such as the Old Royal Library were made from it to the British Museum, established in 1753. The Uffizi in Florence opened entirely as a gallery in 1765, though this function had been gradually taking the building over from the original civil servants\' offices for a long time before. The building now occupied by the Prado in Madrid was built before the French Revolution for the public display of parts of the royal art collection, and similar royal galleries open to the public existed in Vienna, Munich and other capitals. The opening of the Musée du Louvre during the French Revolution (in 1793) as a public museum for much of the former French royal collection certainly marked an important stage in the development of public access to art, transferring ownership to a republican state, but was a continuation of trends already well established.
Most modern public museums and art education programs for children in schools can be traced back to this impulse to have art available to everyone. However, museums do not only provide availability to art, but do also influence the way art is being perceived by the audience, as studies found. Thus, the museum itself is not only a blunt stage for the presentation of art, but plays an active and vital role in the overall perception of art in modern society.
Museums in the United States tend to be gifts from the very rich to the masses. (The Metropolitan Museum of Art in New York City, for example, was created by John Taylor Johnston, a railroad executive whose personal art collection seeded the museum.) But despite all this, at least one of the important functions of art in the 21st century remains as a marker of wealth and social status.
There have been attempts by artists to create art that can not be bought by the wealthy as a status object. One of the prime original motivators of much of the art of the late 1960s and 1970s was to create art that could not be bought and sold. It is \"necessary to present something more than mere objects\" said the major post war German artist Joseph Beuys. This time period saw the rise of such things as performance art, video art, and conceptual art. The idea was that if the artwork was a performance that would leave nothing behind, or was an idea, it could not be bought and sold. \"Democratic precepts revolving around the idea that a work of art is a commodity impelled the aesthetic innovation which germinated in the mid-1960s and was reaped throughout the 1970s. Artists broadly identified under the heading of Conceptual art \... substituting performance and publishing activities for engagement with both the material and materialistic concerns of painted or sculptural form \... \[have\] endeavored to undermine the art object qua object.\" upright=2\|thumb\|250px\|Versailles: Louis Le Vau opened up the interior court to create the expansive entrance *cour d\'honneur*, later copied all over Europe.In the decades since, these ideas have been somewhat lost as the art market has learned to sell limited edition DVDs of video works, invitations to exclusive performance art pieces, and the objects left over from conceptual pieces. Many of these performances create works that are only understood by the elite who have been educated as to why an idea or video or piece of apparent garbage may be considered art. The marker of status becomes understanding the work instead of necessarily owning it, and the artwork remains an upper-class activity. \"With the widespread use of DVD recording technology in the early 2000s, artists, and the gallery system that derives its profits from the sale of artworks, gained an important means of controlling the sale of video and computer artworks in limited editions to collectors.\"
## Controversies
Art has long been controversial, that is to say disliked by some viewers, for a wide variety of reasons, though most pre-modern controversies are dimly recorded, or completely lost to a modern view. Iconoclasm is the destruction of art that is disliked for a variety of reasons, including religious ones. Aniconism is a general dislike of either all figurative images, or often just religious ones, and has been a thread in many major religions. It has been a crucial factor in the history of Islamic art, where depictions of Muhammad remain especially controversial. Much art has been disliked purely because it depicted or otherwise stood for unpopular rulers, parties or other groups. Artistic conventions have often been conservative and taken very seriously by art critics, though often much less so by a wider public. The iconographic content of art could cause controversy, as with late medieval depictions of the new motif of the Swoon of the Virgin in scenes of the Crucifixion of Jesus. The *Last Judgment* by Michelangelo was controversial for various reasons, including breaches of decorum through nudity and the Apollo-like pose of Christ.
The content of much formal art through history was dictated by the patron or commissioner rather than just the artist, but with the advent of Romanticism, and economic changes in the production of art, the artists\' vision became the usual determinant of the content of his art, increasing the incidence of controversies, though often reducing their significance. Strong incentives for perceived originality and publicity also encouraged artists to court controversy. Théodore Géricault\'s *Raft of the Medusa* (`{{c.|1820|lk=no}}`{=mediawiki}), was in part a political commentary on a recent event. Édouard Manet\'s *Le Déjeuner sur l\'Herbe* (1863), was considered scandalous not because of the nude woman, but because she is seated next to men fully dressed in the clothing of the time, rather than in robes of the antique world. John Singer Sargent\'s *Madame Pierre Gautreau (Madam X)* (1884), caused a controversy over the reddish pink used to color the woman\'s ear lobe, considered far too suggestive and supposedly ruining the high-society model\'s reputation. The gradual abandonment of naturalism and the depiction of realistic representations of the visual appearance of subjects in the 19th and 20th centuries led to a rolling controversy lasting for over a century. In the 20th century, Pablo Picasso\'s *Guernica* (1937) used arresting cubist techniques and stark monochromatic oils, to depict the harrowing consequences of a contemporary bombing of a small, ancient Basque town. Leon Golub\'s *Interrogation III* (1981), depicts a female nude, hooded detainee strapped to a chair, her legs open to reveal her sexual organs, surrounded by two tormentors dressed in everyday clothing. Andres Serrano\'s *Piss Christ* (1989) is a photograph of a crucifix, sacred to the Christian religion and representing Christ\'s sacrifice and final suffering, submerged in a glass of the artist\'s own urine. The resulting uproar led to comments in the United States Senate about public funding of the arts.
## Theory
Before Modernism, aesthetics in Western art was greatly concerned with achieving the appropriate balance between different aspects of realism or truth to nature and the ideal; ideas as to what the appropriate balance is have shifted to and fro over the centuries. This concern is largely absent in other traditions of art. The aesthetic theorist John Ruskin, who championed what he saw as the naturalism of J. M. W. Turner, saw art\'s role as the communication by artifice of an essential truth that could only be found in nature.
The definition and evaluation of art has become especially problematic since the 20th century. Richard Wollheim distinguishes three approaches to assessing the aesthetic value of art: the Realist, whereby aesthetic quality is an absolute value independent of any human view; the Objectivist, whereby it is also an absolute value, but is dependent on general human experience; and the Relativist position, whereby it is not an absolute value, but depends on, and varies with, the human experience of different humans.
### Arrival of Modernism {#arrival_of_modernism}
The arrival of Modernism in the late 19th century led to a radical break in the conception of the function of art, and then again in the late 20th century with the advent of postmodernism. Clement Greenberg\'s 1960 article \"Modernist Painting\" defines modern art as \"the use of characteristic methods of a discipline to criticize the discipline itself\". Greenberg originally applied this idea to the Abstract Expressionist movement and used it as a way to understand and justify flat (non-illusionistic) abstract painting:
> Realistic, naturalistic art had dissembled the medium, using art to conceal art; modernism used art to call attention to art. The limitations that constitute the medium of painting---the flat surface, the shape of the support, the properties of the pigment---were treated by the Old Masters as negative factors that could be acknowledged only implicitly or indirectly. Under Modernism these same limitations came to be regarded as positive factors, and were acknowledged openly.
After Greenberg, several important art theorists emerged, such as Michael Fried, T. J. Clark, Rosalind Krauss, Linda Nochlin and Griselda Pollock among others. Though only originally intended as a way of understanding a specific set of artists, Greenberg\'s definition of modern art is important to many of the ideas of art within the various art movements of the 20th century and early 21st century.
Pop artists like Andy Warhol became both noteworthy and influential through work including and possibly critiquing popular culture, as well as the art world. Artists of the 1980s, 1990s, and 2000s expanded this technique of self-criticism beyond *high art* to all cultural image-making, including fashion images, comics, billboards and pornography.
Duchamp once proposed that art is any activity of any kind-everything. However, the way that only certain activities are classified today as art is a social construction. There is evidence that there may be an element of truth to this. In *The Invention of Art: A Cultural History*, Larry Shiner examines the construction of the modern system of the arts, i.e. fine art. He finds evidence that the older system of the arts before our modern system (fine art) held art to be any skilled human activity; for example, Ancient Greek society did not possess the term *art*, but techne. Techne can be understood neither as art or craft, the reason being that the distinctions of art and craft are historical products that came later on in human history. Techne included painting, sculpting and music, but also cooking, medicine, horsemanship, geometry, carpentry, prophecy, and farming, etc.
### New Criticism and the \"intentional fallacy\" {#new_criticism_and_the_intentional_fallacy}
Following Duchamp during the first half of the 20th century, a significant shift to general aesthetic theory took place which attempted to apply aesthetic theory between various forms of art, including the literary arts and the visual arts, to each other. This resulted in the rise of the New Criticism school and debate concerning *the intentional fallacy*. At issue was the question of whether the aesthetic intentions of the artist in creating the work of art, whatever its specific form, should be associated with the criticism and evaluation of the final product of the work of art, or, if the work of art should be evaluated on its own merits independent of the intentions of the artist.
In 1946, William K. Wimsatt and Monroe Beardsley published a classic and controversial New Critical essay entitled \"The Intentional Fallacy\", in which they argued strongly against the relevance of an author\'s intention, or \"intended meaning\" in the analysis of a literary work. For Wimsatt and Beardsley, the words on the page were all that mattered; importation of meanings from outside the text was considered irrelevant, and potentially distracting.
In another essay, \"The Affective Fallacy\", which served as a kind of sister essay to \"The Intentional Fallacy\" Wimsatt and Beardsley also discounted the reader\'s personal/emotional reaction to a literary work as a valid means of analyzing a text. This fallacy would later be repudiated by theorists from the reader-response school of literary theory. Ironically, one of the leading theorists from this school, Stanley Fish, was himself trained by New Critics. Fish criticizes Wimsatt and Beardsley in his 1970 essay \"Literature in the Reader\".
As summarized by Berys Gaut and Paisley Livingston in their essay \"The Creation of Art\": \"Structuralist and post-structuralists theorists and critics were sharply critical of many aspects of New Criticism, beginning with the emphasis on aesthetic appreciation and the so-called autonomy of art, but they reiterated the attack on biographical criticisms\' assumption that the artist\'s activities and experience were a privileged critical topic.\" These authors contend that: \"Anti-intentionalists, such as formalists, hold that the intentions involved in the making of art are irrelevant or peripheral to correctly interpreting art. So details of the act of creating a work, though possibly of interest in themselves, have no bearing on the correct interpretation of the work.\"
Gaut and Livingston define the intentionalists as distinct from formalists stating that: \"Intentionalists, unlike formalists, hold that reference to intentions is essential in fixing the correct interpretation of works.\" They quote Richard Wollheim as stating that, \"The task of criticism is the reconstruction of the creative process, where the creative process must in turn be thought of as something not stopping short of, but terminating on, the work of art itself.\"
### \"Linguistic turn\" and its debate {#linguistic_turn_and_its_debate}
The end of the 20th century fostered an extensive debate known as the linguistic turn controversy, or the \"innocent eye debate\" in the philosophy of art. This debate discussed the encounter of the work of art as being determined by the relative extent to which the conceptual encounter with the work of art dominates over the perceptual encounter with the work of art.
Decisive for the linguistic turn debate in art history and the humanities were the works of yet another tradition, namely the structuralism of Ferdinand de Saussure and the ensuing movement of poststructuralism. In 1981, the artist Mark Tansey created a work of art titled *The Innocent Eye* as a criticism of the prevailing climate of disagreement in the philosophy of art during the closing decades of the 20th century. Influential theorists include Judith Butler, Luce Irigaray, Julia Kristeva, Michel Foucault and Jacques Derrida. The power of language, more specifically of certain rhetorical tropes, in art history and historical discourse was explored by Hayden White. The fact that language is `{{em|not}}`{=mediawiki} a transparent medium of thought had been stressed by a very different form of philosophy of language which originated in the works of Johann Georg Hamann and Wilhelm von Humboldt. Ernst Gombrich and Nelson Goodman in his book *Languages of Art: An Approach to a Theory of Symbols* came to hold that the conceptual encounter with the work of art predominated exclusively over the perceptual and visual encounter with the work of art during the 1960s and 1970s. He was challenged on the basis of research done by the Nobel prize winning psychologist Roger Sperry who maintained that the human visual encounter was not limited to concepts represented in language alone (the linguistic turn) and that other forms of psychological representations of the work of art were equally defensible and demonstrable. Sperry\'s view eventually prevailed by the end of the 20th century with aesthetic philosophers such as Nick Zangwill strongly defending a return to moderate aesthetic formalism among other alternatives.
## Classification disputes {#classification_disputes}
Disputes as to whether or not to classify something as a work of art are referred to as classificatory disputes about art. Classificatory disputes in the 20th century have included cubist and impressionist paintings, Duchamp\'s *Fountain*, the movies, J. S. G. Boggs\' superlative imitations of banknotes, conceptual art, and video games. Philosopher David Novitz has argued that disagreement about the definition of art are rarely the heart of the problem. Rather, \"the passionate concerns and interests that humans vest in their social life\" are \"so much a part of all classificatory disputes about art.\" According to Novitz, classificatory disputes are more often disputes about societal values and where society is trying to go than they are about theory proper. For example, when the *Daily Mail* criticized Hirst\'s and Emin\'s work by arguing \"For 1,000 years art has been one of our great civilising forces. Today, pickled sheep and soiled beds threaten to make barbarians of us all\" they are not advancing a definition or theory about art, but questioning the value of Hirst\'s and Emin\'s work. In 1998, Arthur Danto, suggested a thought experiment showing that \"the status of an artifact as work of art results from the ideas a culture applies to it, rather than its inherent physical or perceptible qualities. Cultural interpretation (an art theory of some kind) is therefore constitutive of an object\'s arthood.\"
*Anti-art* is a label for art that intentionally challenges the established parameters and values of art; it is a term associated with Dadaism and attributed to Marcel Duchamp just before World War I, when he was making art from found objects. One of these, *Fountain* (1917), an ordinary urinal, has achieved considerable prominence and influence on art. Anti-art is a feature of work by Situationist International, the lo-fi Mail art movement, and the Young British Artists, though it is a form still rejected by the Stuckists, who describe themselves as anti-anti-art.
Architecture is often included as one of the visual arts; however, like the decorative arts, or advertising, it involves the creation of objects where the practical considerations of use are essential in a way that they usually are not in a painting, for example.
### Value judgment {#value_judgment}
Somewhat in relation to the above, the word *art* is also used to apply judgments of value, as in such expressions as \"that meal was a work of art\" (the cook is an artist), or \"the art of deception\" (the highly attained level of skill of the deceiver is praised). It is this use of the word as a measure of high quality and high value that gives the term its flavor of subjectivity. Making judgments of value requires a basis for criticism. At the simplest level, a way to determine whether the impact of the object on the senses meets the criteria to be considered *art* is whether it is perceived to be attractive or repulsive. Though perception is always colored by experience, and is necessarily subjective, it is commonly understood that what is not somehow aesthetically satisfying cannot be art. However, \"good\" art is not always or even regularly aesthetically appealing to a majority of viewers. In other words, an artist\'s prime motivation need not be the pursuit of the aesthetic. Also, art often depicts terrible images made for social, moral, or thought-provoking reasons. For example, Francisco Goya\'s painting depicting the Spanish shootings of 3 May 1808 is a graphic depiction of a firing squad executing several pleading civilians. Yet at the same time, the horrific imagery demonstrates Goya\'s keen artistic ability in composition and execution and produces fitting social and political outrage. Thus, the debate continues as to what mode of aesthetic satisfaction, if any, is required to define \'art\'.
The assumption of new values or the rebellion against accepted notions of what is aesthetically superior need not occur concurrently with a complete abandonment of the pursuit of what is aesthetically appealing. Indeed, the reverse is often true, that the revision of what is popularly conceived of as being aesthetically appealing allows for a re-invigoration of aesthetic sensibility, and a new appreciation for the standards of art itself. Countless schools have proposed their own ways to define quality, yet they all seem to agree in at least one point: once their aesthetic choices are accepted, the value of the work of art is determined by its capacity to transcend the limits of its chosen medium to strike some universal chord by the rarity of the skill of the artist or in its accurate reflection in what is termed the *zeitgeist*. Art is often intended to appeal to and connect with human emotion. It can arouse aesthetic or moral feelings, and can be understood as a way of communicating these feelings. Artists express something so that their audience is aroused to some extent, but they do not have to do so consciously. Art may be considered an exploration of the human condition; that is, what it is to be human.
By extension, it has been argued by Emily L. Spratt that the development of generative artificial intelligence, especially in regard to artificial intelligence art, necessitates a re-evaluation of aesthetic theory in art history today and a reconsideration of the limits of human creativity. Music and artificial intelligence has taken a similar path. So too has the use of large language models in generating creative texts.
## Art and law {#art_and_law}
An essential legal issue are art forgeries, plagiarism, replicas and works that are strongly based on other works of art.
Intellectual property law plays a significant role in the art world. Copyright protection is granted to artists for their original works, providing them with exclusive rights to reproduce, distribute, and display their creations. This safeguard empowers artists to govern the usage of their work and safeguard against unauthorized copying or infringement.
The trade in works of art or the export from a country may be subject to legal regulations. Internationally there are also extensive efforts to protect the works of art created. The UN, UNESCO and Blue Shield International try to ensure effective protection at the national level and to intervene directly in the event of armed conflicts or disasters. This can particularly affect museums, archives, art collections and excavation sites. This should also secure the economic basis of a country, especially because works of art are often of tourist importance. The founding president of Blue Shield International, Karl von Habsburg, explained an additional connection between the destruction of cultural property and the cause of flight during a mission in Lebanon in April 2019: \"Cultural goods are part of the identity of the people who live in a certain place. If you destroy their culture, you also destroy their identity. Many people are uprooted, often no longer have any prospects and as a result flee from their homeland.\" In order to preserve the diversity of cultural identity, UNESCO protects the living human treasure through the Convention for the Safeguarding of the Intangible Cultural Heritage.
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Agnostida
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**Agnostida** are an order of extinct arthropods which have classically been seen as a group of highly modified trilobites, though some recent research has doubted this placement. Regardless, they appear to be close relatives as part of the Artiopoda. They are present in the Lower Cambrian fossil record along with trilobites from the Redlichiida, Corynexochida, and Ptychopariida orders, and were highly diverse throughout the Cambrian. Agnostidan diversity severely declined during the Cambrian-Ordovician transition, and the last agnostidans went extinct in the Late Ordovician.
## Systematics
The Agnostida are divided into two suborders --- Agnostina and Eodiscina --- which are then subdivided into a number of families. As a group, agnostids are isopygous, meaning their pygidium is similar in size and shape to their cephalon. Most agnostid species were eyeless.
The systematic position of the order Agnostida within the class Trilobita remains uncertain, and there has been continuing debate whether they are trilobites or a stem group. The challenge to the status has focused on Agnostina partly due to the juveniles of one genus have been found with legs differing dramatically from those of adult trilobites, suggesting they are not members of the lamellipedian clade, of which trilobites are a part. Instead, the limbs of agnostids closely resemble those of stem group crustaceans, although they lack the proximal endite, which defines that group. The study suggested that they were likely the sister taxon to the crustacean stem lineage, and, as such, part of the clade, Crustaceomorpha. Other researchers have suggested, based on a cladistic analyses of dorsal exoskeletal features, that Eodiscina and Agnostida are closely united, and the Eodiscina descended from the trilobite order Ptychopariida. A 2019 study of adult specimens with preserved soft tissue from the Burgess Shale found that agnostidans shared morphological similarities to trilobites and other related artiopodans like nektaspids, and their placement as stem-crustaceans was unsupported. The study recovered agnostidans as the sister group to other trilobites within the Artiopoda.
## Ecology
Scientists have long debated whether the agnostids lived a pelagic or a benthic lifestyle. Their lack of eyes, a morphology not well-suited for swimming, and their fossils found in association with other benthic trilobites suggest a benthic (bottom-dwelling) mode of life. They are likely to have lived on areas of the ocean floor which received little or no light and fed on detritus which descended from upper layers of the sea to the bottom. Their wide geographic dispersion in the fossil record is uncharacteristic of benthic animals, suggesting a pelagic existence. The thoracic segment appears to form a hinge between the head and pygidium allowing for a bivalved ostracodan-type lifestyle. The orientation of the thoracic appendages appears ill-suited for benthic living. Recent work suggests that some agnostids were benthic predators, engaging in cannibalism and possibly pack-hunting behavior.
They are sometimes preserved within the voids of other organisms, for instance within empty hyolith conchs, within sponges, worm tubes and under the carapaces of bivalved arthropods, presumably in order to hide from predators or strong storm currents; or maybe whilst scavenging for food. In the case of the tapering worm tubes *Selkirkia*, trilobites are always found with their heads directed towards the opening of the tube, suggesting that they reversed in; the absence of any moulted carapaces suggests that moulting was not their primary reason for seeking shelter.
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Abstract (law)
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In law, an **abstract** is a brief statement that contains the most important points of a long legal document or of several related legal papers.
## Types of legislation {#types_of_legislation}
The abstract of title, used in real estate transactions, is the more common form of abstract. An abstract of title lists all the owners of a piece of land, a house, or a building before it came into possession of the present owner. The abstract also records all deeds, wills, mortgages, and other documents that affect ownership of the property. An abstract describes a chain of transfers from owner to owner and any agreements by former owners that are binding on later owners.
## Patent law {#patent_law}
In the context of patent law and specifically in prior art searches, searching through abstracts is a common way to find relevant prior art document to question to novelty or inventive step (or non-obviousness in United States patent law) of an invention. Under United States patent law, the abstract may be called \"Abstract of the Disclosure\".
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Ampere
|
The **ampere** (`{{IPAc-en|ˈ|æ|m|p|ɛər|audio=LL-Q1860 (eng)-Naomi Persephone Amethyst (NaomiAmethyst)-ampere.wav}}`{=mediawiki} `{{respell|AM|pair}}`{=mediawiki}, `{{IPAc-en|us|ˈ|æ|m|p|ɪər|audio=LL-Q1860 (eng)-Naomi Persephone Amethyst (NaomiAmethyst)-ampere (alt).wav}}`{=mediawiki} `{{respell|AM|peer}}`{=mediawiki}; symbol: **A**), often shortened to **amp**, is the unit of electric current in the International System of Units (SI). One ampere is equal to 1 coulomb (C) moving past a point per second. It is named after French mathematician and physicist André-Marie Ampère (1775--1836), considered the father of electromagnetism along with Danish physicist Hans Christian Ørsted.
As of the 2019 revision of the SI, the ampere is defined by fixing the elementary charge `{{var|e}}`{=mediawiki} to be exactly `{{physical constants|e|ref=no}}`{=mediawiki}, which means an ampere is an electric current equivalent to `{{val|e=19}}`{=mediawiki} elementary charges moving every `{{val|1.602176634}}`{=mediawiki} seconds, or approximately `{{val|6.241509074|e=18}}`{=mediawiki} elementary charges moving in a second. Prior to the redefinition, the ampere was defined as the current passing through two parallel wires 1 metre apart that produces a magnetic force of `{{val|2|e=-7}}`{=mediawiki} newtons per metre.
The earlier CGS system has two units of current, one structured similarly to the SI\'s and the other using Coulomb\'s law as a fundamental relationship, with the CGS unit of charge defined by measuring the force between two charged metal plates. The CGS unit of current is then defined as one unit of charge per second.
## History
The ampere is named for French physicist and mathematician André-Marie Ampère (1775--1836), who studied electromagnetism and laid the foundation of electrodynamics. In recognition of Ampère\'s contributions to the creation of modern electrical science, an international convention, signed at the 1881 International Exposition of Electricity, established the ampere as a standard unit of electrical measurement for electric current.
The ampere was originally defined as one tenth of the unit of electric current in the centimetre--gram--second system of units. That unit, now known as the abampere, was defined as the amount of current that generates a force of two dynes per centimetre of length between two wires one centimetre apart. The size of the unit was chosen so that the units derived from it in the MKSA system would be conveniently sized.
The \"international ampere\" was an early realization of the ampere, defined as the current that would deposit `{{val|0.001118|u=grams}}`{=mediawiki} of silver per second from a silver nitrate solution. Later, more accurate measurements revealed that this current is `{{val|0.99985|u=A}}`{=mediawiki}.
Since power is defined as the product of current and voltage, the ampere can alternatively be expressed in terms of the other units using the relationship `{{math|1=''I'' = ''P''/''V''}}`{=mediawiki}, and thus 1 A = 1 W/V. Current can be measured by a multimeter, a device that can measure electrical voltage, current, and resistance.
### Former definition in the SI {#former_definition_in_the_si}
Until 2019, the SI defined the ampere as follows:
> The ampere is that constant current which, if maintained in two straight parallel conductors of infinite length, of negligible circular cross-section, and placed one metre apart in vacuum, would produce between these conductors a force equal to `{{val|2|e=-7}}`{=mediawiki} newtons per metre of length.
Ampère\'s force law states that there is an attractive or repulsive force between two parallel wires carrying an electric current. This force was used in the formal definition of the ampere, giving the vacuum magnetic permeability (magnetic constant, `{{math|''μ''<sub>0</sub>}}`{=mediawiki}) a value of exactly 4π × 10^−7^ henries per metre (H/m, equivalent to N/A^2^). The SI unit of charge, the coulomb, was then defined as \"the quantity of electricity carried in 1 second by a current of 1 ampere\". In general, charge `{{mvar|Q}}`{=mediawiki} was determined by steady current `{{mvar|I}}`{=mediawiki} flowing for a time `{{mvar|t}}`{=mediawiki} as `{{math|1=''Q'' = ''It''}}`{=mediawiki}.
This definition of the ampere was most accurately realised using a Kibble balance, but in practice the unit was maintained via Ohm\'s law from the units of electromotive force and resistance, the volt and the ohm, since the latter two could be tied to physical phenomena that are relatively easy to reproduce, the Josephson effect and the quantum Hall effect, respectively.
Techniques to establish the realisation of an ampere had a relative uncertainty of approximately a few parts in 10`{{sup|7}}`{=mediawiki}, and involved realisations of the watt, the ohm and the volt.
### Present definition {#present_definition}
The 2019 revision of the SI defined the ampere by taking the fixed numerical value of the elementary charge `{{mvar|e}}`{=mediawiki} to be `{{physical constants|e|ref=no|unit=no}}`{=mediawiki} when expressed in the unit C, which is equal to A⋅s, where the second is defined in terms of `{{math|∆''ν''<sub>Cs</sub>}}`{=mediawiki}, the unperturbed ground state hyperfine transition frequency of the caesium-133 atom.
The SI unit of charge, the coulomb, \"is the quantity of electricity carried in 1 second by a current of 1 ampere\". Conversely, a current of one ampere is one coulomb of charge (approximately `{{Val|6.241509E18}}`{=mediawiki} elementary charges) going past a given point per second, or equivalently 10^19^ elementary charges every `{{val|1.602176634}}`{=mediawiki} seconds:
$$1\text{ A} = 1\text{ C/s} = \frac{1}{1.602\,176\,634\times10^{-19}}\,e\text{/s} = \frac{10^{19}\,e}{1.602\,176\,634\text{ s}}.$$ With the second defined in terms of `{{math|∆''ν''<sub>Cs</sub>}}`{=mediawiki}, the caesium-133 hyperfine transition frequency, the ampere can be expressed in terms of `{{mvar|e}}`{=mediawiki} and `{{math|∆''ν''<sub>Cs</sub>}}`{=mediawiki}:$1\text{ A} = 1\text{ C/s} = \Big(\frac{10^{19}\,e}{1.602\,176\,634}\Big)\Big(\frac{\Delta\nu_\text{Cs}}{9\,192\,631\,770}\Big) \approx 6.789\,6868\times10^{8}\,e\,\Delta\nu_\text{Cs}.$Constant, instantaneous and average current are expressed in amperes (as in \"the charging current is 1.2 A\") and the charge accumulated (or passed through a circuit) over a period of time is expressed in coulombs (as in \"the battery charge is `{{val|30000|u=C}}`{=mediawiki}\"). The relation of the ampere (A = C/s) to the coulomb (C) is the same as that of the watt (W = J/s) to the joule (J).
## Units derived from the ampere {#units_derived_from_the_ampere}
The international system of units (SI) is based on seven SI base units the second, metre, kilogram, kelvin, ampere, mole, and candela representing seven fundamental types of physical quantity, or \"dimensions\", (time, length, mass, temperature, electric current, amount of substance, and luminous intensity respectively) with all other SI units being defined using these. These SI derived units can either be given special names e.g. watt, volt, lux, etc. or defined in terms of others, e.g. metre per second. The units with special names derived from the ampere are:
Quantity Unit Symbol Meaning In SI base units
------------------------------- --------- -------- -------------------------------- ------------------------
Electric charge coulomb C ampere second A⋅s
Electric potential difference volt V joule per coulomb kg⋅m^2^⋅s^−3^⋅A^−1^
Electrical resistance ohm Ω volt per ampere kg⋅m^2^⋅s^−3^⋅A^−2^
Electrical conductance siemens S ampere per volt or inverse ohm s^3^⋅A^2^⋅kg^−1^⋅m^−2^
Electrical inductance henry H ohm second kg⋅m^2^⋅s^−2^⋅A^−2^
Electrical capacitance farad F coulomb per volt s^4^⋅A^2^⋅kg^−1^⋅m^−2^
Magnetic flux weber Wb volt second kg⋅m^2^⋅s^−2^⋅A^−1^
Magnetic flux density tesla T weber per square metre kg⋅s^−2^⋅A^−1^
There are also some SI units that are frequently used in the context of electrical engineering and electrical appliances, but are defined independently of the ampere, notably the hertz, joule, watt, candela, lumen, and lux.
## SI prefixes {#si_prefixes}
Like other SI units, the ampere can be modified by adding a prefix that multiplies it by a power of 10. `{{SI multiples
| unit=ampere
| symbol=A
}}`{=mediawiki}
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Anthophyta
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The **anthophytes** are a paraphyletic grouping of plant taxa bearing flower-like reproductive structures. The group, once thought to be a clade, contained the angiosperms -- the extant flowering plants, such as roses and grasses -- as well as the Gnetales and the extinct Bennettitales.
Detailed morphological and molecular studies have shown that the group is not actually monophyletic, with proposed floral homologies of the gnetophytes and the angiosperms having evolved in parallel. This makes it easier to reconcile molecular clock data that suggests that the angiosperms diverged from the gymnosperms around 320-300 mya.
Some more recent studies have used the word anthophyte to describe a hypothetical group which includes the angiosperms and a variety of extinct seed plant groups (with various suggestions including at least some of the following groups: glossopterids, corystosperms, Petriellales Pentoxylales, Bennettitales and Caytoniales), but not the Gnetales.
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Alismatales
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The **Alismatales** (**alismatids**) are an order of flowering plants including about 4,500 species. Plants assigned to this order are mostly tropical or aquatic. Some grow in fresh water, some in marine habitats. Perhaps the most important food crop in the order is the taro plant, *Colocasia esculenta*.
## Description
The Alismatales comprise herbaceous flowering plants of often aquatic and marshy habitats, and the only monocots known to have green embryos other than the Amaryllidaceae. They also include the only marine angiosperms growing completely submerged, the seagrasses. The flowers are usually arranged in inflorescences, and the mature seeds lack endosperm.
Both marine and freshwater forms include those with staminate flowers that detach from the parent plant and float to the surface. There they can pollinate carpellate flowers floating on the surface via long pedicels. In others, pollination occurs underwater, where pollen may form elongated strands, increasing chance of success. Most aquatic species have a totally submerged juvenile phase, and flowers are either floating or emerge above the water\'s surface. Vegetation may be totally submersed, have floating leaves, or protrude from the water. Collectively, they are commonly known as \"water plantain\".
## Taxonomy
The Alismatales contain about 165 genera in 13 families, with a cosmopolitan distribution. Phylogenetically, they are basal monocots, diverging early in evolution relative to the lilioid and commelinid monocot lineages. Together with the Acorales, the Alismatales are referred to informally as the alismatid monocots.
### Early systems {#early_systems}
The Cronquist system (1981) places the Alismatales in subclass Alismatidae, class Liliopsida \[= monocotyledons\] and includes only three families as shown:
- Alismataceae
- Butomaceae
- Limnocharitaceae
Cronquist\'s subclass Alismatidae conformed fairly closely to the order Alismatales as defined by APG, minus the Araceae.
The Dahlgren system places the Alismatales in the superorder Alismatanae in the subclass Liliidae \[= monocotyledons\] in the class Magnoliopsida \[= angiosperms\] with the following families included:
- Alismataceae
- Aponogetonaceae
- Butomaceae
- Hydrocharitaceae
- Limnocharitaceae
In Tahktajan\'s classification (1997), the order Alismatales contains only the Alismataceae and Limnocharitaceae, making it equivalent to the Alismataceae as revised in APG-III. Other families included in the Alismatates as currently defined are here distributed among 10 additional orders, all of which are assigned, with the following exception, to the Subclass Alismatidae. Araceae in Tahktajan 1997 is assigned to the Arales and placed in the Subclass Aridae; Tofieldiaceae to the Melanthiales and placed in the Liliidae.
### Angiosperm Phylogeny Group {#angiosperm_phylogeny_group}
The Angiosperm Phylogeny Group system (APG) of 1998 and APG II (2003) assigned the Alismatales to the monocots, which may be thought of as an unranked clade containing the families listed below. The biggest departure from earlier systems (see below) is the inclusion of family Araceae. By its inclusion, the order has grown enormously in number of species. The family Araceae alone accounts for about a hundred genera, totaling over two thousand species. The rest of the families together contain only about five hundred species, many of which are in very small families.
The APG III system (2009) differs only in that the Limnocharitaceae are combined with the Alismataceae; it was also suggested that the genus *Maundia* (of the Juncaginaceae) could be separated into a monogeneric family, the Maundiaceae, but the authors noted that more study was necessary before the Maundiaceae could be recognized.
- order Alismatales *sensu* APG III
: family Alismataceae (*including* Limnocharitaceae)
: family Aponogetonaceae
: family Araceae
: family Butomaceae
: family Cymodoceaceae
: family Hydrocharitaceae
: family Juncaginaceae
: family Posidoniaceae
: family Potamogetonaceae
: family Ruppiaceae
: family Scheuchzeriaceae
: family Tofieldiaceae
: family Zosteraceae
In APG IV (2016), it was decided that evidence was sufficient to elevate *Maundia* to family level as the monogeneric Maundiaceae. The authors considered including a number of the smaller orders within the Juncaginaceae, but an online survey of botanists and other users found little support for this \"lumping\" approach. Consequently, the family structure for APG IV is:
\*: family Alismataceae (*including* Limnocharitaceae)
\*: family Aponogetonaceae
\*: family Araceae
\*: family Butomaceae
\*: family Cymodoceaceae
\*: family Hydrocharitaceae
\*: family Juncaginaceae
\*: family Maundiaceae
\*: family Posidoniaceae
\*: family Potamogetonaceae
\*: family Ruppiaceae
\*: family Scheuchzeriaceae
\*: family Tofieldiaceae
\*: family Zosteraceae
### Phylogeny
Cladogram showing the orders of monocots (Lilianae *sensu* Chase & Reveal) based on molecular phylogenetic evidence:
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Apiales
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The **Apiales** are an order of flowering plants, included in the asterid group of dicotyledons. Well-known members of Apiales include carrots, celery, coriander, parsley, parsnips, poison hemlock, ginseng, ivies, and pittosporums.
Apiales consist of nine families, with the type family being the celery, carrot or parsley family, Apiaceae.
## Taxonomy
There are nine accepted families within the Apiales, though there is some slight variation and in particular, the Torriceliaceae may also be divided.
- Apiaceae (carrot family)
- Araliaceae (ginseng family)
- Griseliniaceae
- Myodocarpaceae
- Pennantiaceae
- Pittosporaceae
- Torricelliaceae
The present understanding of the Apiales is fairly recent and is based upon comparison of DNA sequences by phylogenetic methods. The circumscriptions of some of the families have changed. In 2009, one of the subfamilies of Araliaceae was shown to be polyphyletic.
The order Apiales is placed within the asterid group of eudicots as circumscribed by the APG III system. Within the asterids, Apiales belongs to an unranked group called the campanulids, and within the campanulids, it belongs to a clade known in phylogenetic nomenclature as Apiidae. In 2010, a subclade of Apiidae named Dipsapiidae was defined to consist of the three orders: Apiales, Paracryphiales, and Dipsacales.
Under the Cronquist system, only the Apiaceae and Araliaceae were included here, and the restricted order was placed among the rosids rather than the asterids. The Pittosporaceae were placed within the Rosales, and many of the other forms within the family Cornaceae. *Pennantia* was in the family Icacinaceae. In the classification system of Dahlgren the families Apiaceae and Araliaceae were placed in the order Ariales, in the superorder Araliiflorae (also called Aralianae).
## Gynoecia
The largest and obviously closely related families of Apiales are Araliaceae, Myodocarpaceae and Apiaceae, which resemble each other in the structure of their gynoecia. In this respect however, the Pittosporaceae is notably distinct from them.
Typical syncarpous gynoecia exhibit four vertical zones, determined by the extent of fusion of the carpels. In most plants, the synascidiate (i.e. \"united bottle-shaped\") and symplicate zones are fertile and bear the ovules. Each of the first three families possess mainly bi- or multilocular ovaries in a gynoecium with a long synascidiate, but very short symplicate zone, where the ovules are inserted at their transition, the so-called cross-zone (or \"Querzone\").
In gynoecia of the Pittosporaceae, the symplicate is much longer than the synascidiate zone, and the ovules are arranged along the first. Members of the latter family consequently have unilocular ovaries with a single cavity between adjacent carpels.
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Asterales
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**Asterales** (`{{IPAc-en|ˌ|æ|s|t|ə|ˈ|r|eɪ|l|iː|z|audio=LL-Q1860 (eng)-Naomi Persephone Amethyst (NaomiAmethyst)-Asterales.wav}}`{=mediawiki} `{{respell|ASS|tər|RAY|leez}}`{=mediawiki}) is an order of dicotyledonous flowering plants that includes the large family Asteraceae (or Compositae) known for composite flowers made of florets, and ten families related to the Asteraceae. While asterids in general are characterized by fused petals, composite flowers consisting of many florets create the false appearance of separate petals (as found in the rosids).
The order is cosmopolitan (plants found throughout most of the world including desert and frigid zones), and includes mostly herbaceous species, although a small number of trees (such as the *Lobelia deckenii*, the giant lobelia, and *Dendrosenecio*, giant groundsels) and shrubs are also present.
Asterales are organisms that seem to have evolved from one common ancestor. Asterales share characteristics on morphological and biochemical levels. Synapomorphies (a character that is shared by two or more groups through evolutionary development) include the presence in the plants of oligosaccharide inulin, a nutrient storage molecule used instead of starch; and unique stamen morphology. The stamens are usually found around the style, either aggregated densely or fused into a tube, probably an adaptation in association with the plunger (brush; or secondary) pollination that is common among the families of the order, wherein pollen is collected and stored on the length of the pistil.
## Taxonomy
The name and order Asterales is botanically venerable, dating back to at least 1926 in the Hutchinson system of plant taxonomy when it contained only five families, of which only two are retained in the APG III classification. Under the Cronquist system of taxonomic classification of flowering plants, Asteraceae was the only family in the group, but newer systems (such as APG II and APG III) have expanded it to 11. In the classification system of Rolf Dahlgren the Asterales were in the superorder Asteriflorae (also called Asteranae).
The order **Asterales** currently includes 11 families, the largest of which are the Asteraceae, with about 25,000 species, and the Campanulaceae (bellflowers), with about 2,000 species. The remaining families count together for less than 1500 species. The two large families are cosmopolitan, with many of their species found in the Northern Hemisphere, and the smaller families are usually confined to Australia and the adjacent areas, or sometimes South America.
Only the Asteraceae have composite flower heads; the other families do not, but share other characteristics such as storage of inulin that define the 11 families as more closely related to each other than to other plant families or orders such as the rosids.
The phylogenetic tree according to APG III for the Campanulid clade is as below.
### Phylogeny
Although most extant species of Asteraceae are herbaceous, the examination of the basal members in the family suggests that the common ancestor of the family was an arborescent plant, a tree or shrub, perhaps adapted to dry conditions, radiating from South America. Less can be said about the Asterales themselves with certainty, although since several families in Asterales contain trees, the ancestral member is most likely to have been a tree or shrub.
Because all clades are represented in the Southern Hemisphere but many not in the Northern Hemisphere, it is natural to conjecture that there is a common southern origin to them. Asterales belong to angiosperms or flowering plants, a clade that appeared about 140 million years ago. The Asterales order probably originated in the Cretaceous (145 -- 66 Mya) on the supercontinent Gondwana which broke up from 184 -- 80 Mya, forming the area that is now Australia, South America, Africa, India and Antarctica.
Asterales contain about 14% of eudicot diversity. From an analysis of relationships and diversities within the Asterales and with their superorders, estimates of the age of the beginning of the Asterales have been made, which range from 116 Mya to 82Mya. However few fossils have been found, of the Menyanthaceae-Asteraceae clade in the Oligocene, about 29 Mya.
Fossil evidence of the Asterales is rare and belongs to rather recent epochs, so the precise estimation of the order\'s age is quite difficult. An Oligocene (34 -- 23 Mya) pollen is known for Asteraceae and Goodeniaceae, and seeds from Oligocene and Miocene (23 -- 5.3 Mya) are known for Menyanthaceae and Campanulaceae respectively. According to molecular clock calculations, the lineage that led to Asterales split from other plants about 112 million years ago or 94 million years ago.
## Biogeography
The core Asterales are Stylidiaceae (six genera), APA clade (Alseuosmiaceae, Phellinaceae and Argophyllaceae, together seven genera), MGCA clade (Menyanthaceae, Goodeniaceae, Calyceraceae, in total twenty genera), and Asteraceae (about sixteen hundred genera). Other Asterales are Rousseaceae (four genera), Campanulaceae (eighty-four genera) and Pentaphragmataceae (one genus).
All Asterales families are represented in the Southern Hemisphere; however, Asteraceae and Campanulaceae are cosmopolitan and Menyanthaceae nearly so.
## Uses
The Asterales, by dint of being a super-set of the family Asteraceae, include some species grown for food, including the sunflower (*Helianthus annuus*), lettuce (*Lactuca sativa*) and chicory (*Cichorium*). Many are also used as spices and traditional medicines.
Asterales are common plants and have many known uses. For example, pyrethrum (derived from Old World members of the genus *Chrysanthemum*) is a natural insecticide with minimal environmental impact. Wormwood, derived from a genus that includes the sagebrush, is used as a source of flavoring for absinthe, a bitter classical liquor of European origin.
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Allocution
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An **allocution**, or **allocutus**, is a formal statement made to a court by the defendant who has been found guilty before being sentenced. It is part of the criminal procedure in some jurisdictions using common law.
## Concept
An allocution allows the defendant to explain why the sentence should be lenient. In plea bargains, an allocution may be required of the defendant. The defendant explicitly admits specifically and in detail the actions and their reasons in exchange for a reduced sentence.
In principle, that removes any doubt as to the exact nature of the defendant\'s guilt in the matter.
The term *allocution* is used generally only in jurisdictions in the United States, but there are vaguely similar processes in other common law countries. In many other jurisdictions, it is for the defense lawyer to mitigate on their client\'s behalf, and the defendant rarely has the opportunity to speak.
## Australia
In Australia, the term *allocutus* is used by the Clerk of Arraigns or another formal associate of the court.
It is generally phrased as: \"Prisoner at the Bar, you have been found Guilty by a jury of your peers of the offence of XYZ. Do you have anything to say as to why the sentence of this Court should not now be passed upon you?\"
The defense counsel will then make a *plea in mitigation* (also called *submissions on penalty*) in an attempt to mitigate the relative seriousness of the offense, and heavily refer to and rely upon the defendant\'s previous good character and good works, if any.
The right to make a plea in mitigation is absolute: if a judge or magistrate refuses to hear such a plea or does not properly consider it, the sentence can be overturned on appeal.
## United States {#united_states}
In most of the United States, defendants are allowed the opportunity to allocute before a sentence is passed. Some jurisdictions hold that as an absolute right. In its absence, a sentence but not the conviction may be overturned, resulting in the need for a new sentencing hearing. In the federal system, Federal Rules of Criminal Procedure 32(i)(4) provides that the court must \"address the defendant personally in order to permit the defendant to speak or present any information to mitigate the sentence\".
The Federal Public Defender recommends that defendants speak in terms of how a lenient sentence will be sufficient but not greater than necessary to comply with the statutory directives set forth in `{{uscsub|18|3553|a}}`{=mediawiki}.
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Affidavit
|
An ***italic=no*** (`{{IPAc-en|audio=LL-Q1860 (eng)-Back ache-affidavit.wav|ˌ|æ|f|ɪ|ˈ|d|eɪ|v|ɪ|t}}`{=mediawiki} `{{respell|AF|ih|DAY|vit}}`{=mediawiki}; Medieval Latin for \"he has declared under oath\") is a written statement voluntarily made by an *affiant* or *deponent* under an oath or affirmation which is administered by a person who is authorized to do so by law. Such a statement is witnessed as to the authenticity of the affiant\'s signature by a taker of oaths, such as a notary public or commissioner of oaths. An affidavit is a type of verified statement or showing, or containing a verification, meaning it is made under oath on penalty of perjury. It serves as evidence for its veracity and is required in court proceedings.
## Definition
An affidavit is typically defined as a written declaration or statement that is sworn or affirmed before a person who has authority to administer an oath. There is no general defined form for an affidavit, although for some proceedings an affidavit must satisfy legal or statutory requirements in order to be considered. An affidavit may include,
- a *commencement* which identifies the affiant;
- an *attestation* clause, usually a jurat, at the end certifying that the affiant made the statement under oath on the specified date;
- signatures of the affiant and person who administered the oath.
In some cases, an introductory clause, called a *preamble*, is added attesting that the affiant personally appeared before the authenticating authority. An affidavit may also recite that the statement it records was made under penalty of perjury.
An affidavit that is prepared for use within the context of litigation may also include a caption that identifies the venue and parties to the relevant judicial proceedings.
## Worldwide
### Australia
On 2 March 2016, the High Court of Australia held that the ACT Uniform Evidence Legislation is neutral in the way sworn evidence and unsworn evidence is treated as being of equal weight.
### United Kingdom {#united_kingdom}
The term \"affidavit\" is used in the UK. According to the UK government website, \"The affidavit can be sworn or affirmed by a solicitor, notary or commissioner for oaths (for a charge) or by an authorised member of court staff.\"
### India
In Indian law, although an affidavit may be taken as proof of the facts stated therein, the courts have no jurisdiction to admit evidence by way of affidavit. Affidavit is not treated as \"evidence\" within the meaning of Section 3 of the Evidence Act. However, it was held by the Supreme Court that an affidavit can be used as evidence only if the court so orders for sufficient reasons, namely, the right of the opposite party to have the deponent produced for cross-examination. Therefore, an affidavit cannot ordinarily be used as evidence in absence of a specific order of the court.
### Sri Lanka {#sri_lanka}
In Sri Lanka, under the Oaths Ordinance, with the exception of a court-martial, a person may submit an affidavit signed in the presence of a commissioner for oaths or a justice of the peace.
### Ireland
Affidavits are made in a similar way as to England and Wales, although \"make oath\" is sometimes omitted. An affirmed affidavit may be substituted for an sworn affidavit in most cases for those opposed to swearing oaths. The person making the affidavit is known as the deponent and signs the affidavit. The affidavit concludes in the standard format \"sworn/affirmed (declared) before me, \[name of commissioner for oaths/solicitor\], a commissioner for oaths (solicitor), on the \[date\] at \[location\] in the county/city of \[county/city\], and I know the deponent\", and it is signed and stamped by the commissioner for oaths. It is important that the Commissioner states his/her name clearly, sometimes documents are rejected when the name cannot be ascertained.
In August 2020, a new method of filing affidavits came into force. Under Section 21 of the Civil Law and Criminal Law (Miscellaneous Provisions) Act 2020 witnesses are no longer required to swear before God or make an affirmation when filing an affidavit. Instead, witnesses will make a non-religious \"statement of truth\" and, if it is breached, will be liable for up to one year in prison if convicted summarily or, upon conviction on indictment, to a maximum fine of €250,000 or imprisonment for a term not exceeding 5 years, or both.
This is designed to replace affidavits and statutory declarations in situations where the electronic means of lodgement or filing of documents with the Court provided for in Section 20 is utilised. As of January 2022, it has yet to be adopted widely, and it is expected it will not be used for some time by lay litigants who will still lodge papers in person.
### United States {#united_states}
thumb\|upright=0.9\|Affidavit signed by Harriet Tubman
In American jurisprudence, under the rules for hearsay, admission of an unsupported affidavit as evidence is unusual (especially if the affiant is not available for cross-examination) with regard to material facts which may be dispositive of the matter at bar. Affidavits from persons who are dead or otherwise incapacitated, or who cannot be located or made to appear, may be accepted by the court, but usually only in the presence of corroborating evidence. An affidavit which reflected a better grasp of the facts close in time to the actual events may be used to refresh a witness\'s recollection. Materials used to refresh recollection are admissible as evidence. If the affiant is a party in the case, the affiant\'s opponent may be successful in having the affidavit admitted as evidence, as statements by a party-opponent are admissible through an exception to the hearsay rule.
Affidavits are typically included in the response to interrogatories. Requests for admissions under Federal Rule of Civil Procedure 36, however, are not required to be sworn.
When a person signs an affidavit, that person is eligible to take the stand at a trial or evidentiary hearing. One party may wish to summon the affiant to verify the contents of the affidavit, while the other party may want to cross-examine the affiant about the affidavit.
Some types of motions will not be accepted by the court unless accompanied by an independent sworn statement or other evidence in support of the need for the motion. In such a case, a court will accept an affidavit from the filing attorney in support of the motion, as certain assumptions are made, to wit: The affidavit in place of sworn testimony promotes judicial economy. The lawyer is an officer of the court and knows that a false swearing by them, if found out, could be grounds for severe penalty up to and including disbarment. The lawyer if called upon would be able to present independent and more detailed evidence to prove the facts set forth in his affidavit.
Affidavits should not be confused with unsworn declarations under penalty of perjury. In federal courts and about 20 states as of 2006, unsworn declarations under penalty of perjury are authorized by statute as acceptable in lieu of affidavits. The key differences are that an unsworn declaration does not bear the jurat of a notary public and the declarant is not required to swear an oath or affirmation. Rather, the signature of the declarant under a carefully worded phrase binding them to the truth of their statements \"under penalty of perjury\" is deemed as a matter of law to be sufficiently solemn to remind the declarant of their duty to tell the truth, the whole truth, and nothing but the truth (that is, the oath they would normally swear if they were testifying in person in a court of law). The point of such affidavit substitution statutes is that unsworn declarations can be prepared and executed far more quickly and economically than affidavits, in that the witness need not meet personally with a notary public for the notarization process.
The acceptance of an affidavit by one society does not confirm its acceptance as a legal document in other jurisdictions. Equally, the acceptance that a lawyer is an officer of the court (for swearing the affidavit) is not a given. This matter is addressed by the use of the apostille, a means of certifying the legalization of a document for international use under the terms of the 1961 Hague Convention Abolishing the Requirement of Legalization for Foreign Public Documents. Documents which have been notarized by a notary public, and certain other documents, and then certified with a conformant apostille, are accepted for legal use in all the nations that have signed the Hague Convention. Thus most affidavits now require to be apostilled if used for cross border issues.
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A Clockwork Orange (novel)
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***A Clockwork Orange*** is a dystopian satirical black comedy novel by English writer Anthony Burgess, published on March 17, 1962. It is set in a near-future society that has a youth subculture of extreme violence. The teenage protagonist, Alex, narrates his violent exploits and his experiences with state authorities intent on reforming him. The book is partially written in a Russian-influenced argot called \"Nadsat\", which takes its name from the Russian suffix that is equivalent to \'-teen\' in English. According to Burgess, the novel was a *jeu d\'esprit* written in just three weeks.
In 2005, *A Clockwork Orange* was included on *Time* magazine\'s list of the 100 best English-language novels written since 1923, and it was named by Modern Library and its readers as one of the 100 best English-language novels of the 20th century. The original manuscript of the book has been kept at McMaster University\'s William Ready Division of Archives and Research Collections in Hamilton, Ontario, Canada since the institution purchased the documents in 1971. It is considered one of the most influential dystopian books.
In 2022, the novel was included on the \"Big Jubilee Read\" list of 70 books by Commonwealth authors selected to celebrate the Platinum Jubilee of Elizabeth II.
## Plot summary {#plot_summary}
### Part 1: Alex\'s world {#part_1_alexs_world}
Alex is a 15-year-old gang leader living in a near-future dystopian city. His friends (\"droogs\" in the novel\'s Anglo-Russian slang, \"Nadsat\") and fellow gang members are Dim, a slow-witted bruiser, who is the gang\'s muscle; Georgie, an ambitious second-in-command; and Pete, who mostly plays along as the droogs indulge their taste for \"ultra-violence\" (random, violent mayhem). Characterised as a sociopath and hardened juvenile delinquent, Alex is also intelligent, quick-witted, and enjoys classical music; he is particularly fond of Beethoven, whom he calls \"Lovely Ludwig Van\".
The droogs sit in their favourite hangout, the Korova Milk Bar, drinking \"milk-plus\" (milk laced with the customer\'s drug of choice) to prepare for a night of ultra-violence. They assault a scholar walking home from the public library; rob a shop, leaving the owner and his wife bloodied and unconscious; beat up a beggar; then scuffle with a rival gang. Joyriding through the countryside in a stolen car, they break into an isolated cottage and terrorise the young couple living there, beating the husband and gang-raping his wife. The husband is a writer working on a manuscript entitled *A Clockwork Orange*, and Alex contemptuously reads out a paragraph that states the novel\'s main theme before shredding the manuscript. At the Korova, Alex strikes Dim for his crude response to a woman\'s singing of an operatic passage, and strains within the gang become apparent. At home in his parents\' flat, Alex plays classical music at top volume, which he describes as giving him orgasmic bliss before falling asleep.
Alex feigns illness to his parents to stay out of school the next day. Following an unexpected visit from P. R. Deltoid, his \"post-corrective adviser\", Alex visits a record store, where he meets two pre-teen girls. He invites them back to the flat, where he drugs and rapes them. That night after a nap, Alex finds his droogs in a mutinous mood, waiting downstairs in the torn-up and graffitied lobby. Georgie challenges Alex for leadership of the gang, demanding that they focus on higher-value targets in their robberies. Alex quells the rebellion by slashing Dim\'s hand and fighting with Georgie, then soothes the gang by agreeing to Georgie\'s plan to rob the home of a wealthy elderly woman. Alex breaks in and knocks the woman unconscious, but when he hears sirens and opens the door to flee, Dim strikes him as revenge for the earlier fight. The gang abandons Alex on the front step to be arrested by the police; while in custody, he learns that the woman has died from her injuries.
### Part 2: The Ludovico Technique {#part_2_the_ludovico_technique}
Alex is convicted of murder and sentenced to 14 years in prison. His parents visit one day to inform him that Georgie has been killed in a botched robbery. Two years into his term, he has obtained a job in one of the prison chapels, playing music on the stereo to accompany the Sunday Christian services. After his fellow cellmates blame him for beating a troublesome cellmate to death, he is chosen to undergo an experimental behaviour modification treatment called the Ludovico Technique in exchange for having the remainder of his sentence commuted. The technique is a form of aversion therapy in which Alex is injected with nausea-inducing drugs while watching graphically violent films, eventually conditioning him to become severely ill at the mere thought of violence. As an unintended consequence, the soundtrack to one of the films, Beethoven\'s Fifth Symphony, renders Alex unable to enjoy his beloved classical music as before.
The technique\'s effectiveness is demonstrated to a group of VIPs, who watch as Alex collapses before a man who slaps him and abases himself before a scantily clad young woman. Although the prison chaplain accuses the state of stripping Alex of free will, the government officials on the scene are pleased with the results, and Alex is released from prison.
### Part 3: After prison {#part_3_after_prison}
Alex returns to his parents\' flat, only to find that they are letting his room to a lodger. Now homeless, he wanders the streets and enters a public library, hoping to learn of a painless method for committing suicide. The old scholar whom Alex had assaulted in Part 1 finds him and beats him with the help of several friends. Two policemen come to Alex\'s rescue, but they turn out to be Dim and Billyboy, a former rival gang leader. They take Alex outside town, brutalise him, and abandon him there. Alex collapses at the door of an isolated cottage, realising too late that it is the one he and his droogs invaded in Part 1.
The writer, F. Alexander, still lives here, but his wife has since died of what he believes to be injuries she sustained in the rape. He does not recognise Alex but gives him shelter and questions him about the conditioning he has undergone. Alexander and his colleagues, all highly critical of the government, plan to use Alex as a symbol of state brutality and thus prevent the incumbent government from being re-elected. After Alex inadvertently reveals that he was the ringleader of the home invasion, he is removed from the cottage and locked in an upper-storey bedroom as a relentless barrage of classical music plays over speakers. He attempts suicide by leaping from the window.
Alex wakes up in a hospital, where he is courted by government officials, anxious to counter the bad publicity created by his suicide attempt. He is informed that F. Alexander has been \"put away\" for Alex\'s protection and his own. Alex is offered a well-paying job if he agrees to side with the government once discharged. A round of tests reveals that his old violent impulses have returned, indicating that the hospital doctors have undone the effects of his conditioning. As photographers snap pictures, Alex daydreams of orgiastic violence and reflects, \"I was cured all right.\"
In the final chapter, Alex---now 18 years old and working for the nation\'s musical recording archives---finds himself halfheartedly preparing for another night of crime with a new gang (Len, Rick, and Bully). After a chance encounter with Pete, who has reformed and married, Alex finds himself taking less and less pleasure in acts of senseless violence. He begins contemplating giving up crime himself to become a productive member of society and start a family of his own while reflecting on the notion that his children could end up being just as destructive as he has been, if not more so.
## Omission of the final chapter in the US {#omission_of_the_final_chapter_in_the_us}
The book has three parts, each with seven chapters. Burgess has stated that the total of 21 chapters was an intentional nod to the age of 21 being recognised as a milestone in human maturation. The 21st chapter was omitted from the editions published in the United States prior to 1986. In the introduction to the updated American text (these newer editions include the missing 21st chapter), Burgess explains that when he first brought the book to an American publisher, he was told that US audiences would never go for the final chapter, in which Alex sees the error of his ways, decides he has lost his taste for violence and resolves to turn his life around.
At the American publisher\'s insistence, Burgess allowed its editors to cut the redeeming final chapter from the US version, so that the tale would end on a darker note, with Alex becoming his old, ultraviolent self again -- an ending which the publisher insisted would be \"more realistic\" and appealing to a US audience. The film adaptation, directed by Stanley Kubrick, is based on the American edition of the book, and is considered to be \"badly flawed\" by Burgess. Kubrick called Chapter 21 \"an extra chapter\" and claimed that he had not read the original version until he had virtually finished the screenplay and that he had never given serious consideration to using it. In Kubrick\'s opinion -- as in the opinion of other readers, including the original American editor -- the final chapter was unconvincing and inconsistent with the book. Kubrick\'s stance was unusual when compared to the standard Hollywood practice of producing films with the familiar tropes of resolving moral messages and good triumphing over evil before the film\'s end.
## Characters
- **Alex**: The novel\'s protagonist and leader among his droogs. He often refers to himself as \"Your Humble Narrator\". Having coaxed two ten-year-old girls into his bedroom, Alex refers to himself as \"Alexander the Large\" while raping them; this was later the basis for Alex\'s claimed surname *DeLarge* in the 1971 film.
- **George**, **Georgie** or **Georgie Boy**: Effectively Alex\'s greedy second-in-command. Georgie attempts to undermine Alex\'s status as leader of the gang and take over their gang as the new leader. He is later killed during a botched robbery while Alex is in prison.
- **Pete**: The only one who does not take particular sides when the droogs fight among themselves. He later meets and marries a girl named Georgina, renouncing his violent ways and even losing his former (Nadsat) speech patterns. A chance encounter with Pete in the final chapter influences Alex to realise that he has grown bored with violence and recognise that human energy is better expended on creation than destruction.
- **Dim**: An idiotic and thoroughly gormless member of the gang, persistently condescended to by Alex, but respected to some extent by his droogs for his formidable fighting abilities, his weapon of choice being a length of bike chain. He later becomes a police officer, exacting his revenge on Alex for the abuse he once suffered under his command.
- **P. R. Deltoid**: A criminal rehabilitation social worker assigned the task of keeping Alex on the straight and narrow. He seemingly has no clue about dealing with young people, and is devoid of empathy or understanding for his troublesome charge. Indeed, when Alex is arrested for murdering an old woman and then ferociously beaten by several police officers, Deltoid simply spits on him.
- **Prison Chaplain**: The character who first questions whether it is moral to turn a violent person into a behavioural automaton who can make no choice in such matters. This is the only character who is truly concerned about Alex\'s welfare; he is not taken seriously by Alex, though. He is nicknamed by Alex \"prison charlie\" or \"chaplin\", a pun on Charlie Chaplin.
- **Billyboy**: A rival of Alex\'s. Early on in the story, Alex and his droogs battle Billyboy and his droogs, which ends abruptly when the police arrive. Later, after Alex is released from prison, Billyboy (along with Dim, who like Billyboy has become a police officer) rescues Alex from a mob, then subsequently beats him in a location out of town.
- **Prison Governor**: The man who decides to let Alex \"choose\" to be the first reformed by the Ludovico technique.
- **The Minister of the Interior**: The government high-official who determined that the Ludovico\'s technique will be used to cut recidivism. He is referred to as *the Minister of Interior or Inferior* by Alex.
- **Dr Branom**: A scientist, co-developer of the Ludovico technique. He appears friendly and almost paternal towards Alex at first, before forcing him into the theatre and what Alex calls the \"chair of torture\".
- **Dr Brodsky**: Branom\'s colleague and co-developer of the Ludovico technique. He seems much more passive than Branom and says considerably less.
- **F. Alexander**: An author who was in the process of typing his magnum opus *A Clockwork Orange* when Alex and his droogs broke into his house, beat him, tore up his work and then brutally gang-raped his wife, which caused her subsequent death. He is left deeply scarred by these events and when he encounters Alex two years later, he uses him as a guinea pig in a sadistic experiment intended to prove the Ludovico technique unsound. The government imprisons him afterwards. He is given the name Frank Alexander in the film.
- **Cat Woman**: An indirectly named woman who blocks Alex\'s gang\'s entrance scheme, and threatens to shoot Alex and set her cats on him if he does not leave. After Alex breaks into her house, she fights with him, ordering her cats to join the melee, but reprimands Alex for fighting them off. She sustains a fatal blow to the head during the scuffle. She is given the name Miss Weathers in the film.
## Analysis
### Background
*A Clockwork Orange* was written in Hove, then a senescent English seaside town. Burgess had arrived back in Britain after his stint abroad to see that much had changed. A youth culture had developed, based around coffee bars, pop music and teenage gangs. England was gripped by fears over juvenile delinquency. Burgess stated that the novel\'s inspiration was his first wife Lynne\'s beating by a gang of drunk American servicemen stationed in England during World War II. She subsequently miscarried. In its investigation of free will, the book\'s target is ostensibly the concept of behaviourism, pioneered by such figures as B. F. Skinner. Burgess later stated that he wrote the book in three weeks.
### Title
Burgess has offered several clarifications about the meaning and origin of its title:
- He had overheard the phrase \"as queer as a clockwork orange\" in a London pub in 1945 and assumed it was a Cockney expression. In *Clockwork Marmalade*, an essay published in the *Listener* in 1972, he said that he had heard the phrase several times since that occasion. He also explained the title in response to a question from William Everson on the television programme *Camera Three* in 1972, `{{blockquote |text = Well, the title has a very different meaning but only to a particular generation of London Cockneys. It's a phrase which I heard many years ago and so fell in love with, I wanted to use it, the title of the book. But the phrase itself I did not make up. The phrase "as queer as a clockwork orange" is good old East London slang and it didn't seem to me necessary to explain it. Now, obviously, I have to give it an extra meaning. I've implied an extra dimension. I've implied the junction of the organic, the lively, the sweet – in other words, life, the orange – and the mechanical, the cold, the disciplined. I've brought them together in this kind of [[oxymoron]], this sour-sweet word.
|author = Anthony Burgess
|title = An examination of Kubrick's A Clockwork Orange<ref>[https://www.youtube.com/watch?v=ejM3odcn3Tk#t=7m23s ''An examination of Kubrick's A Clockwork Orange''] {{Webarchive|url=https://web.archive.org/web/20161109093620/https://www.youtube.com/watch?v=ejM3odcn3Tk=7m23s |date=9 November 2016}} ''Camera Three'': Creative Arts Television, 2010-08-04. '''(Video)'''</ref><ref>[http://www.malcolmtribute.freeiz.com/aco/review.html ''Clockwork Orange: A review with William Everson''] {{Webarchive|url=https://web.archive.org/web/20120710224804/http://www.malcolmtribute.freeiz.com/aco/review.html |date=10 July 2012}}. Retrieved: 2012-03-11.</ref>}}`{=mediawiki}
No other record of the expression being used before 1962 has ever appeared, with Kingsley Amis going so far as to note in his *Memoirs* (1991) that no trace of it appears in Eric Partridge\'s *Dictionary of Historical Slang*. However, saying \"as queer as \...\" followed by an improbable object: \"\... a clockwork orange\", or \"\... a four-speed walking stick\" or \"\... a left-handed corkscrew\" etc. predates Burgess\'s novel. An early example, \"as queer as Dick\'s hatband\", appeared in 1796, and was alluded to in 1757.
- His second explanation was that it was a pun on the Malay word *orang*, meaning \"man\". The novella contains no other Malay words or links.
- In a prefatory note to *A Clockwork Orange: A Play with Music*, he wrote that the title was a metaphor for \"an organic entity, full of juice and sweetness and agreeable odour, being turned into a mechanism\".
- In his essay *Clockwork Oranges*, Burgess asserts that \"this title would be appropriate for a story about the application of Pavlovian or mechanical laws to an organism which, like a fruit, was capable of colour and sweetness\".
- While addressing the reader in a letter before some editions of the book, the author says that when a man ceases to have free will, they are no longer a man. \"Just a clockwork orange\", a shiny, appealing object, but \"just a toy to be wound-up by either God or the Devil, or (what is increasingly replacing both) the State.\"
This title alludes to the protagonist\'s negative emotional responses to feelings of evil which prevent the exercise of his free will subsequent to the administration of the Ludovico Technique. To induce this conditioning, Alex is forced to watch scenes of violence on a screen that are systematically paired with negative physical stimulation. The negative physical stimulation takes the form of nausea and \"feelings of terror\", which are caused by an emetic medicine administered just before the presentation of the films.
In its original drafts, Burgess used the working title \'The Ludovico Technique,\' as he himself described in the foreword in the April 1995 publication. Along with removing the 21st chapter as insisted by his publisher in the original 1962 edition, he would also change the finished product\'s name to its current title.
### Use of slang {#use_of_slang}
The book, narrated by Alex, contains many words in a slang argot which Burgess invented for the book, called Nadsat. It is a mix of modified Slavic words, Cockney rhyming slang and derived Russian (like *baboochka*). For instance, these terms have the following meanings in Nadsat: *droog* (друг) = friend; *moloko* (молоко) = milk; *gulliver* (голова) = head; *malchick* (мальчик) or *malchickiwick* = boy; *soomka* (сумка) = sack or bag; *Bog* (Бог) = God; *horrorshow* (хорошо) = good; *prestoopnick* (преступник) = criminal; *rooker* (рука) = hand; *cal* (кал) = crap; *veck* (человек) = man or guy; *litso* (лицо) = face; *malenky* (маленький) = little; and so on. Some words Burgess invented himself or just adapted from existing languages. Compare Polari.
One of Alex\'s doctors explains the language to a colleague as \"odd bits of old rhyming slang; a bit of gypsy talk, too. But most of the roots are Slav propaganda. Subliminal penetration.\" Some words are not derived from anything, but merely easy to guess, e.g. \"in-out, in-out\" or \"the old in-out\" means sexual intercourse. *Cutter*, however, means \"money\", because \"cutter\" rhymes with \"bread-and-butter\"; this is rhyming slang, which is intended to be impenetrable to outsiders (especially eavesdropping policemen). Additionally, slang like *appypolly loggy* (\"apology\") seems to derive from school boy slang. This reflects Alex\'s age of 15.
In the first edition of the book, no key was provided, and the reader was left to interpret the meaning from the context. In his appendix to the restored edition, Burgess explained that the slang would keep the book from seeming dated, and served to muffle \"the raw response of pornography\" from the acts of violence.
The term `{{anchor|Ultraviolence}}`{=mediawiki}\"ultraviolence\", referring to excessive or unjustified violence, was coined by Burgess in the book, which includes the phrase \"do the ultra-violent\". The term\'s association with aesthetic violence has led to its use in the media.
### Banning and censorship history in the US {#banning_and_censorship_history_in_the_us}
The first major incident of censorship of *A Clockwork Orange* took place in 1973, when a bookseller was arrested for selling the novel (although the charges were later dropped). In 1976, *A Clockwork Orange* was removed from an Aurora, Colorado high school because of \"objectionable language\". A year later in 1977 it was removed from high school classrooms in Westport, Massachusetts over similar concerns with \"objectionable\" language. In 1982, it was removed from two Anniston, Alabama libraries, later to be reinstated on a restricted basis. However, each of these instances came after the release of Stanley Kubrick\'s popular 1971 film adaptation of *A Clockwork Orange*, itself the subject of much controversy after exposing a much larger part of the populace to the themes of the novel. In 2024 the book was banned in Texas by the Katy Independent School District on the basis that the novel is \"adopting, supporting, or promoting gender fluidity\" despite also pronouncing a bullying policy that protects infringements on the rights of the student.
## Reception
### Initial response {#initial_response}
*The Sunday Telegraph* review was positive, and described the book as \"entertaining \... even profound\". Kingsley Amis in *The Observer* acclaimed the novel as \"cheerful horror\", writing \"Mr Burgess has written a fine farrago of outrageousness, one which incidentally suggests a view of juvenile violence I can\'t remember having met before\". Malcolm Bradbury wrote \"All of Mr Burgess\'s powers as a comic writer, which are considerable, have gone into the rich language of his inverted Utopia. If you can stomach the horrors, you\'ll enjoy the manner\". Roald Dahl called it \"a terrifying and marvellous book\". Many reviewers praised the inventiveness of the language, but expressed unease at the violent subject matter. *The Spectator* praised Burgess\'s \"extraordinary technical feat\" but was uncomfortable with \"a certain arbitrariness about the plot which is slightly irritating\". *New Statesman* acclaimed Burgess for addressing \"acutely and savagely the tendencies of our time\" but called the book \"a great strain to read\". *The Sunday Times* review was negative, and described the book as \"a very ordinary, brutal and psychologically shallow story\". *The Times* also reviewed the book negatively, describing it as \"a somewhat clumsy experiment with science fiction \[with\] clumsy cliches about juvenile delinquency\". The violence was criticised as \"unconvincing in detail\".
### Writer\'s appraisal {#writers_appraisal}
Burgess dismissed *A Clockwork Orange* as \"too didactic to be artistic\". He said that the violent content of the novel \"nauseated\" him.
In 1985, Burgess published *Flame into Being: The Life and Work of D. H. Lawrence* and while discussing *Lady Chatterley\'s Lover* in his biography, Burgess compared the notoriety of D. H. Lawrence\'s novel with *A Clockwork Orange*: \"We all suffer from the popular desire to make the known notorious. The book I am best known for, or only known for, is a novel I am prepared to repudiate: written a quarter of a century ago, a *jeu d\'esprit* knocked off for money in three weeks, it became known as the raw material for a film which seemed to glorify sex and violence. The film made it easy for readers of the book to misunderstand what it was about, and the misunderstanding will pursue me until I die. I should not have written the book because of this danger of misinterpretation, and the same may be said of Lawrence and *Lady Chatterley\'s Lover*.\"
### Awards and nominations and rankings {#awards_and_nominations_and_rankings}
- 1983 -- Prometheus Award (Preliminary Nominee)
- 1999 -- Prometheus Award (Nomination)
- 2002 -- Prometheus Award (Nomination)
- 2003 -- Prometheus Award (Nomination)
- 2006 -- Prometheus Award (Nomination)
- 2008 -- Prometheus Award (Hall of Fame Award)
*A Clockwork Orange* was chosen by *Time* magazine as one of the 100 best English-language books from 1923 to 2005.
## Adaptations
A 1965 film by Andy Warhol entitled *Vinyl* was an adaptation of Burgess\'s novel.
The best known adaptation of the novel is the 1971 film *A Clockwork Orange* by Stanley Kubrick, with Malcolm McDowell as Alex. In 1987, Burgess published a stage play titled *A Clockwork Orange: A Play with Music*. The play includes songs, written by Burgess, which are inspired by Beethoven and Nadsat slang.
A manga anthology by Osamu Tezuka entitled *Tokeijikake no Ringo* (Clockwork Apple) was released in 1983.
In 1988, a German adaptation of *A Clockwork Orange* at the intimate theatre of Bad Godesberg featured a musical score by the German punk rock band Die Toten Hosen which, combined with orchestral clips of Beethoven\'s Ninth Symphony and \"other dirty melodies\" (so stated by the subtitle), was released on the album *Ein kleines bisschen Horrorschau*. The track *Hier kommt Alex* became one of the band\'s signature songs.
In February 1990, another musical version was produced at the Barbican Theatre in London by the Royal Shakespeare Company. Titled *A Clockwork Orange: 2004*, it received mostly negative reviews, with John Peter of *The Sunday Times* of London calling it \"only an intellectual *Rocky Horror Show*\", and John Gross of *The Sunday Telegraph* calling it \"a clockwork lemon\". Even Burgess himself, who wrote the script based on his novel, was disappointed. According to *The Evening Standard*, he called the score, written by Bono and The Edge of the rock group U2, \"neo-wallpaper\". Burgess had originally worked alongside the director of the production, Ron Daniels, and envisioned a musical score that was entirely classical. Unhappy with the decision to abandon that score, he heavily criticised the band\'s experimental mix of hip-hop, liturgical, and gothic music. Lise Hand of *The Irish Independent* reported The Edge as saying that Burgess\'s original conception was \"a score written by a novelist rather than a songwriter\". Calling it \"meaningless glitz\", Jane Edwardes of *20/20* magazine said that watching this production was \"like being invited to an expensive French Restaurant -- and being served with a Big Mac.\"
In 1994, Chicago\'s Steppenwolf Theater put on a production of *A Clockwork Orange* directed by Terry Kinney. The American premiere of novelist Anthony Burgess\'s own adaptation of his *A Clockwork Orange* starred K. Todd Freeman as Alex. In 2001, UNI Theatre (Mississauga, Ontario) presented the Canadian premiere of the play under the direction of Terry Costa.
In 2002, Godlight Theatre Company presented the New York Premiere adaptation of *A Clockwork Orange* at Manhattan Theatre Source. The production went on to play at the SoHo Playhouse (2002), Ensemble Studio Theatre (2004), 59E59 Theaters (2005) and the Edinburgh Festival Fringe (2005). While at Edinburgh, the production received rave reviews from the press while playing to sold-out audiences. The production was directed by Godlight\'s artistic director, Joe Tantalo.
In 2003, Los Angeles director Brad Mays and the ARK Theatre Company staged a multi-media adaptation of *A Clockwork Orange*, which was named \"Pick of the Week\" by the *LA Weekly* and nominated for three of the 2004 LA Weekly Theater Awards: Direction, Revival Production (of a 20th-century work), and Leading Female Performance. Vanessa Claire Smith won Best Actress for her gender-bending portrayal of Alex, the music-loving teenage sociopath. This production utilised three separate video streams outputted to seven onstage video monitors -- six 19-inch and one 40-inch. In order to preserve the first-person narrative of the book, a pre-recorded video stream of Alex, \"your humble narrator\", was projected onto the 40-inch monitor, thereby freeing the onstage character during passages which would have been awkward or impossible to sustain in the breaking of the fourth wall.
An adaptation of the work, based on the original novel, the film and Burgess\'s own stage version, was performed by the SiLo Theatre in Auckland, New Zealand in early 2007.
In 2021, the International Anthony Burgess Foundation premiered a webpage cataloging various productions of *A Clockwork Orange* from around the world.
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Museum of Work
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The **Museum of Work** (*Arbetets museum*) is a museum located in Norrköping, Sweden. The museum is located in the *Strykjärn* (Clothes iron), a former weaving mill in the old industrial area on the Motala ström river in the city centre of Norrköping. The former textile factory Holmens Bruk (sv) operated in the building from 1917 to 1962.
The museum documents work and everyday life by collecting personal stories about people\'s professional lives from both the past and the present. The museum\'s archive contain material from memory collections and documentation projects.
Since 2009, the museum also houses the EWK -- Center for Political Illustration Art, which is based on work of the satirist Ewert Karlsson (1918--2004). For decades he was frequently published in the Swedish tabloid, *Aftonbladet*.
## Overview
The museum is a national central museum with the task of preserving and telling about work and everyday life. It has, among other things, exhibitions on the terms and conditions of the work and the history of the industrial society. The museum is also known to highlight gender perspective in their exhibitions.
The work museum documents work and everyday life by collecting personal stories, including people\'s professional life from both the past and present. In the museum\'s archive, there is a rich material of memory collections and documentation projects -- over 2600 interviews, stories and photodocumentations have been collected since the museum opened.
The museum is also a support for the country\'s approximately 1,500 working life museums that are old workplaces preserved to convey their history.
## Exhibitions
The Museum of Work shows exhibitions going on over several years, but also shorter exhibitions -- including several photo exhibitions on themes that can be linked to work and everyday life.
### The history of Alva {#the_history_of_alva}
The history of Alva Karlsson is the only exhibition in the museum that is permanent. The exhibition connects to the museum\'s building and its history as part of the textile industry in Norrköping. Alva worked as a rollers between the years 1927 -- 1962.
### Industriland
One of the museum long-term exhibitions is Industriland -- when Sweden became modern, the exhibition was in 2007--2013 and consisted of an ongoing bond with various objects that were somehow significant both for working life and everyday during the period 1930--1980. The exhibition also consisted of presentations of the working life museums in Sweden and a number of rooms with themes such as: leisure, world, living and consumption.
### Framtidsland (Future country) {#framtidsland_future_country}
In 2014, the exhibition was inaugurated that takes by where Industriland ends: Future country. It is an exhibition that investigates what a sustainable society is will be part of the museum\'s exhibitions until 2019. The exhibition consists of materials that are designed based on conversations between young people and researchers around Sweden. The exhibition addresses themes such as work, environment and everyday life. A tour version of the exhibition is given in the locations Falun, Kristianstad and Örebro.
## EWK -- The Center for Political Illustration Art {#ewk_the_center_for_political_illustration_art}
Since 2009, the Museum also houses EWK -- center for political illustration art. The museum preserves, develops and conveys the political illustrator Ewert Karlsson\'s production. The museum also holds theme exhibitions with national and international political illustrators with the aim of highlighting and strengthening the political art.
| 2025-08-01T00:00:00 |
859 |
Aztlan Underground
|
**Aztlan Underground** is a band from Los Angeles, California that combines Hip-Hop, Punk Rock, Jazz, and electronic music with Chicano and Native American themes, and indigenous instrumentation. They are often cited as progenitors of Chicano rap.
## Background
The band traces its roots to the late-1980s hardcore scene in the Eastside of Los Angeles. They have played rapcore, with elements of punk, hip hop, rock, funk, jazz, indigenous music, and spoken word. Indigenous drums, flutes, and rattles are also commonly used in their music. Their lyrics often address the family and economic issues faced by the Chicano community, and they have been noted as activists for that community.
As an example of the politically active and culturally important artists in Los Angeles in the 1990s, Aztlan Underground appeared on *Culture Clash* on Fox in 1993; and was part of *Breaking Out*, a concert on pay per view in 1998, The band was featured in the independent films *Algun Dia* and *Frontierland* in the 1990s, and on the upcoming *Studio 49*. The band has been mentioned or featured in various newspapers and magazines: *the Vancouver Sun*, *New Times*, *BLU Magazine* (an underground hip hop magazine), *BAM Magazine*, *La Banda Elastica Magazine*, and the *Los Angeles Times* calendar section. The band is also the subject of a chapter in the book *It\'s Not About a Salary*, by Brian Cross.
Aztlan Underground remains active in the community, lending their voice to annual events such as The Farce of July, and the recent movement to recognize Indigenous People\'s Day in Los Angeles and beyond.
In addition to forming their own label, Xicano Records and Film, Aztlan Underground were signed to the Basque record label Esan Ozenki in 1999 which enabled them to tour Spain extensively and perform in France and Portugal. Aztlan Underground have also performed in Canada, Australia, and Venezuela. The band has been recognized for their music with nominations in the *New Times* 1998 \"Best Latin Influenced\" category, the *BAM Magazine* 1999 \"Best Rock en Español\" category, and the *LA Weekly* 1999 \"Best Hip Hop\" category. The release of their eponymous third album on August 29, 2009, was met with positive reviews and earned the band four Native American Music Award (NAMMY) nominations in 2010.
## Discography
### *Decolonize*
Year:1995
1. \"Teteu Innan\"
2. \"Killing Season\"
3. \"Lost Souls\"
4. \"My Blood Is Red\"
5. \"Natural Enemy\"
6. \"Sacred Circle\"
7. \"Blood On Your Hands\"
8. \"Interlude\"
9. \"Aug 2 the 9\"
10. \"Indigena\"
11. \"Lyrical Drive By\"
### *Sub-Verses* {#sub_verses}
Year:1998
1. \"Permiso\"
2. \"They Move In Silence\"
3. \"No Soy Animal\"
4. \"Killing Season\"
5. \"Blood On Your Hands\"
6. \"Reality Check\"
7. \"Lemon Pledge\"
8. \"Revolution\"
9. \"Preachers of the Blind State\"
10. \"Lyrical Drive-By\"
11. \"Nahui Ollin\"
12. \"How to Catch a Bullet\"
13. \"Ik Otik\"
14. \"Obsolete Man\"
15. \"Decolonize\"
16. \"War Flowers\"
### *Aztlan Underground* {#aztlan_underground}
Year: 2009
1. \"Moztlitta\"
2. \"Be God\"
3. \"Light Shines\"
4. \"Prey\"
5. \"In the Field\"
6. \"9 10 11 12\"
7. \"Smell the Dead\"
8. \"Sprung\"
9. \"Medicine\"
10. \"Acabando\"
11. \"Crescent Moon\"
| 2025-08-01T00:00:00 |
875 |
Analog Brothers
|
**Analog Brothers** were an experimental hip hop band featuring Tracy \"Ice-T\" Marrow (Ice Oscillator) on keyboards, drums and vocals, Keith \"Kool Keith\" Thornton (Keith Korg) on bass, strings and vocals, Marc Live (Marc Moog) on drums, violins and vocals, Christopher \"Black Silver\" Rodgers (Silver Synth) on synthesizer, lazar bell and vocals, and Rex Colonel \"Pimpin\' Rex\" Doby Jr. (Rex Roland JX3P) on keyboards, vocals and production.
## Music
The group\'s only studio album *Pimp to Eat* featured guest appearances by various members of Rhyme Syndicate, Odd Oberheim, Jacky Jasper (who appears as Jacky Jasper on the song \"We Sleep Days\" and H-Bomb on \"War\"), D.J. Cisco from S.M., Synth-A-Size Sisters and Teflon.
## Legacy
While the group only recorded one album together as the Analog Brothers, a few bootlegs of its live concert performances, including freestyles with original lyrics, have occasionally surfaced online. After *Pimp to Eat*, the Analog Brothers continued performing together in various line ups. Kool Keith and Marc Live joined with Jacky Jasper to release two albums as KHM. Marc Live rapped with Ice-T\'s group SMG. Marc also formed a group with Black Silver called Live Black, but while five of their tracks were released on a demo CD sold at concerts, Live Black\'s first album has yet to be released.
In 2008, Ice-T and Black Silver toured together as Black Ice, and released an album together called *Urban Legends*.
In 2013, Black Silver and newest member to Analog Brothers, Kiew Kurzweil (Kiew Nikon of Kinetic) collaborated on the joint album called *Slang Banging (Return to Analog)* with production by Junkadelic Music. In addition to all this, the Analog Brothers continue to make frequent appearances on each other\'s solo albums.
## Discography
- 2000 - *2005 A.D.* (single), Ground Control Records/Nu Gruv
- 2000 - *Pimp to Eat* (LP), Ground Control Records/Mello Music Group
- 2014 - *Slang Banging (Return to Analog)*, Junkadelic Music
| 2025-08-01T00:00:00 |
890 |
Anna Kournikova
|
**Anna Sergeyevna Kournikova Iglesias** (née **Kournikova**; *Анна Сергеевна Курникова*; `{{IPA|ru|ˈanːə sʲɪrˈɡʲejɪvnə ˈkurnʲɪkəvə|lang|Anna_kournikova.ogg}}`{=mediawiki}; born 7 June 1981) is a Russian model and television personality, and former professional tennis player. Her appearance and celebrity status made her one of the best known tennis stars worldwide. At the peak of her fame, fans looking for images of Kournikova made her name one of the most common search strings on Google Search.
Despite never winning a singles title, she reached No. 8 in the world in 2000. She achieved greater success playing doubles, where she was at times the world No. 1 player. With Martina Hingis as her partner, she won Grand Slam titles in Australia in 1999 and 2002, and the WTA Championships in 1999 and 2000. They referred to themselves as the \"Spice Girls of Tennis\".
Kournikova retired from professional tennis in 2003 due to serious back and spinal problems, including a herniated disk. She lives in Miami Beach, Florida, and played in occasional exhibitions and in doubles for the St. Louis Aces of World TeamTennis before the team folded in 2011. She was a new trainer for season 12 of the television show *The Biggest Loser*, replacing Jillian Michaels, but did not return for season 13. In addition to her tennis and television work, Kournikova serves as a Global Ambassador for Population Services International\'s \"Five & Alive\" program, which addresses health crises facing children under the age of five and their families.
## Early life {#early_life}
Kournikova was born in Moscow, Russia, on 7 June 1981. Her father, Sergei Kournikov (born 1961), a former Greco-Roman wrestling champion, eventually earned a PhD and was a professor at the University of Physical Culture and Sport in Moscow. As of 2001, he was still a part-time martial arts instructor there. Her mother Alla (born 1963) had been a 400-metre runner. Her younger half-brother, Allan, is a youth golf world champion who was featured in the 2013 documentary film *The Short Game*.
Sergei Kournikov has said, \"We were young and we liked the clean, physical life, so Anna was in a good environment for sport from the beginning\".
Kournikova received her first tennis racquet as a New Year gift in 1986 at the age of five. Describing her early regimen, she said, \"I played two times a week from age six. It was a children\'s program. And it was just for fun; my parents didn\'t know I was going to play professionally, they just wanted me to do something because I had lots of energy. It was only when I started playing well at seven that I went to a professional academy. I would go to school, and then my parents would take me to the club, and I\'d spend the rest of the day there just having fun with the kids.\" In 1986, Kournikova became a member of the Spartak Tennis Club, coached by Larissa Preobrazhenskaya. In 1989, at the age of eight, Kournikova began appearing in junior tournaments, and by the following year, was attracting attention from tennis scouts across the world. She signed a management deal at age ten and went to Bradenton, Florida, to train at Nick Bollettieri\'s celebrated tennis academy.
## Tennis career {#tennis_career}
### 1989--1997: early years and breakthrough {#early_years_and_breakthrough}
Following her arrival in the United States, she became prominent on the tennis scene. At the age of 14, she won the European Championships and the Italian Open Junior tournament. In December 1995, she became the youngest player to win the 18-and-under division of the Junior Orange Bowl tennis tournament. By the end of the year, Kournikova was crowned the ITF Junior World Champion U-18 and Junior European Champion U-18.
Earlier, in September 1995, Kournikova, still only 14 years of age, debuted in the WTA Tour, when she received a wildcard into the qualifications at the WTA tournament in Moscow, the Moscow Ladies Open, and qualified before losing in the second round of the main draw to third-seeded Sabine Appelmans. She also reached her first WTA Tour doubles final in that debut appearance -- partnering with 1995 Wimbledon girls\' champion in both singles and doubles Aleksandra Olsza, she lost the title match to Meredith McGrath and Larisa Savchenko-Neiland.
In February--March 1996, Kournikova won two ITF titles, in Midland, Michigan and Rockford, Illinois. Still only 14 years of age, in April 1996 she debuted at the Fed Cup for Russia, the youngest player ever to participate and win a match.
In 1996, she started playing under a new coach, Ed Nagel. Her six-year association with Nagel was successful. At 15, she made her Grand Slam debut, reaching the fourth round of the 1996 US Open, losing to Steffi Graf, the eventual champion. After this tournament, Kournikova\'s ranking jumped from No. 144 to debut in the Top 100 at No. 69. Kournikova was a member of the Russian delegation to the 1996 Olympic Games in Atlanta, Georgia. In 1996, she was named WTA Newcomer of the Year, and she was ranked No. 57 in the end of the season.
Kournikova entered the 1997 Australian Open as world No. 67, where she lost in the first round to world No. 12, Amanda Coetzer. At the Italian Open, Kournikova lost to Amanda Coetzer in the second round. She reached the semi-finals in the doubles partnering with Elena Likhovtseva, before losing to the sixth seeds Mary Joe Fernández and Patricia Tarabini.
At the French Open, Kournikova made it to the third round before losing to world No. 1, Martina Hingis. She also reached the third round in doubles with Likhovtseva. At the Wimbledon Championships, Kournikova became only the second woman in the open era to reach the semi-finals in her Wimbledon debut, the first being Chris Evert in 1972. There she lost to eventual champion Martina Hingis.
At the US Open, she lost in the second round to the eleventh seed Irina Spîrlea. Partnering with Likhovtseva, she reached the third round of the women\'s doubles event. Kournikova played her last WTA Tour event of 1997 at Porsche Tennis Grand Prix in Filderstadt, losing to Amanda Coetzer in the second round of singles, and in the first round of doubles to Lindsay Davenport and Jana Novotná partnering with Likhovtseva. She broke into the top 50 on 19 May, and was ranked No. 32 in singles and No. 41 in doubles at the end of the season.
### 1998--2000: success and stardom {#success_and_stardom}
In 1998, Kournikova broke into the WTA\'s top 20 rankings for the first time, when she was ranked No. 16. At the Australian Open, Kournikova lost in the third round to world No. 1 player, Martina Hingis. She also partnered with Larisa Savchenko-Neiland in women\'s doubles, and they lost to eventual champions Hingis and Mirjana Lučić in the second round. Although she lost in the second round of the Paris Open to Anke Huber in singles, Kournikova reached her second doubles WTA Tour final, partnering with Larisa Savchenko-Neiland. They lost to Sabine Appelmans and Miriam Oremans. Kournikova and Savchenko-Neiland reached their second consecutive final at the Linz Open, losing to Alexandra Fusai and Nathalie Tauziat. At the Miami Open, Kournikova reached her first WTA Tour singles final, before losing to Venus Williams in the final.
Kournikova then reached two consecutive quarterfinals, at Amelia Island and the Italian Open, losing respectively to Lindsay Davenport and Martina Hingis. At the German Open, she reached the semi-finals in both singles and doubles, partnering with Larisa Savchenko-Neiland. At the French Open Kournikova had her best result at this tournament, making it to the fourth round before losing to Jana Novotná. She also reached her first Grand Slam doubles semi-finals, losing with Savchenko-Neiland to Lindsay Davenport and Natasha Zvereva. During her quarterfinals match at the grass-court Eastbourne Open versus Steffi Graf, Kournikova injured her thumb, which would eventually force her to withdraw from the 1998 Wimbledon Championships. However, she won that match, but then withdrew from her semi-finals match against Arantxa Sánchez Vicario. Kournikova returned for the Du Maurier Open and made it to the third round, before losing to Conchita Martínez. At the US Open Kournikova reached the fourth round before losing to Arantxa Sánchez Vicario. Her strong year qualified her for the year-end 1998 WTA Tour Championships, but she lost to Monica Seles in the first round. However, with Seles, she won her first WTA doubles title, in Tokyo, beating Mary Joe Fernández and Arantxa Sánchez Vicario in the final. At the end of the season, she was ranked No. 10 in doubles.
At the start of the 1999 season, Kournikova advanced to the fourth round in singles at the Australian Open before losing to Mary Pierce. In the doubles Kournikova won her first Grand Slam title, partnering with Martina Hingis to defeat Lindsay Davenport and Natasha Zvereva in the final. At the Tier I Family Circle Cup, Kournikova reached her second WTA Tour final, but lost to Martina Hingis. She then defeated Jennifer Capriati, Lindsay Davenport and Patty Schnyder on her route to the Bausch & Lomb Championships semi-finals, losing to Ruxandra Dragomir. At The French Open, Kournikova reached the fourth round before losing to eventual champion Steffi Graf. Once the grass-court season commenced in England, Kournikova lost to Nathalie Tauziat in the semi-finals in Eastbourne. At Wimbledon, Kournikova lost to Venus Williams in the fourth round. She also reached the final in mixed doubles, partnering with Jonas Björkman, but they lost to Leander Paes and Lisa Raymond. Kournikova again qualified for year-end WTA Tour Championships, but lost to Mary Pierce in the first round, and ended the season as World No. 12.
While Kournikova had a successful singles season, she was even more successful in doubles. After their victory at the Australian Open, she and Martina Hingis won tournaments in Indian Wells, Rome, Eastbourne and the WTA Tour Championships, and reached the final of The French Open where they lost to Serena and Venus Williams. Partnering with Elena Likhovtseva, Kournikova also reached the final in Stanford. On 22 November 1999 she reached the world No. 1 ranking in doubles, and ended the season at this ranking. Kournikova and Hingis were presented with the WTA Award for Doubles Team of the Year.
Kournikova opened her 2000 season winning the Gold Coast Open doubles tournament partnering with Julie Halard. She then reached the singles semi-finals at the Medibank International Sydney, losing to Lindsay Davenport. At the Australian Open, she reached the fourth round in singles and the semi-finals in doubles. That season, Kournikova reached eight semi-finals (Sydney, Scottsdale, Stanford, San Diego, Luxembourg, Leipzig and Tour Championships), seven quarterfinals (Gold Coast, Tokyo, Amelia Island, Hamburg, Eastbourne, Zürich and Philadelphia) and one final. On 20 November 2000 she broke into top 10 for the first time, reaching No. 8. She was also ranked No. 4 in doubles at the end of the season. Kournikova was once again, more successful in doubles. She reached the final of the US Open in mixed doubles, partnering with Max Mirnyi, but they lost to Jared Palmer and Arantxa Sánchez Vicario. She also won six doubles titles -- Gold Coast (with Julie Halard), Hamburg (with Natasha Zvereva), Filderstadt, Zürich, Philadelphia and the Tour Championships (with Martina Hingis).
### 2001--2003: injuries and final years {#injuries_and_final_years}
Her 2001 season was plagued by injuries, including a left foot stress fracture which made her withdraw from 12 tournaments, including the French Open and Wimbledon. She underwent surgery in April. She reached her second career grand slam quarterfinals, at the Australian Open. Kournikova then withdrew from several events due to continuing problems with her left foot and did not return until Leipzig. With Barbara Schett, she won the doubles title in Sydney. She then lost in the finals in Tokyo, partnering with Iroda Tulyaganova, and at San Diego, partnering with Martina Hingis. Hingis and Kournikova also won the Kremlin Cup. At the end of the 2001 season, she was ranked No. 74 in singles and No. 26 in doubles.
Kournikova regained some success in 2002. She reached the semi-finals of Auckland, Tokyo, Acapulco and San Diego, and the final of the China Open, losing to Anna Smashnova. This was Kournikova\'s last singles final. With Martina Hingis, she lost in the final at Sydney, but they won their second Grand Slam title together, the Australian Open. They also lost in the quarterfinals of the US Open. With Chanda Rubin, Kournikova played the semi-finals of Wimbledon, but they lost to Serena and Venus Williams. Partnering with Janet Lee, she won the Shanghai title. At the end of 2002 season, she was ranked No. 35 in singles and No. 11 in doubles.
In 2003, Anna Kournikova achieved her first Grand Slam match victory in two years at the Australian Open. She defeated Henrieta Nagyová in the first round, and then lost to Justine Henin-Hardenne in the 2nd round. She withdrew from Tokyo due to a sprained back suffered at the Australian Open and did not return to Tour until Miami. On 9 April, in what would be the final WTA match of her career, Kournikova dropped out in the first round of the Family Circle Cup in Charleston, due to a left adductor strain. Her singles world ranking was 67. She reached the semi-finals at the ITF tournament in Sea Island, before withdrawing from a match versus Maria Sharapova due to the adductor injury. She lost in the first round of the ITF tournament in Charlottesville. She did not compete for the rest of the season due to a continuing back injury. At the end of the 2003 season and her professional career, she was ranked No. 305 in singles and No. 176 in doubles.
Kournikova\'s two Grand Slam doubles titles came in 1999 and 2002, both at the Australian Open in the Women\'s Doubles event with partner Martina Hingis. Kournikova proved a successful doubles player on the professional circuit, winning 16 tournament doubles titles, including two Australian Opens and being a finalist in mixed doubles at the US Open and at Wimbledon, and reaching the No. 1 ranking in doubles in the WTA Tour rankings. Her pro career doubles record was 200--71. However, her singles career plateaued after 1999. For the most part, she managed to retain her ranking between 10 and 15 (her career high singles ranking was No.8), but her expected finals breakthrough failed to occur; she only reached four finals out of 130 singles tournaments, never in a Grand Slam event, and never won one.
Her singles record is 209--129. Her final playing years were marred by a string of injuries, especially back injuries, which caused her ranking to erode gradually. As a personality Kournikova was among the most common search strings for both articles and images in her prime.
### 2004--present: exhibitions and World Team Tennis {#present_exhibitions_and_world_team_tennis}
Kournikova has not played on the WTA Tour since 2003, but still plays exhibition matches for charitable causes. In late 2004, she participated in three events organized by Elton John and by fellow tennis players Serena Williams and Andy Roddick. In January 2005, she played in a doubles charity event for the Indian Ocean tsunami with John McEnroe, Andy Roddick, and Chris Evert. In November 2005, she teamed up with Martina Hingis, playing against Lisa Raymond and Samantha Stosur in the WTT finals for charity. Kournikova is also a member of the St. Louis Aces in the World Team Tennis (WTT), playing doubles only.
In September 2008, Kournikova showed up for the 2008 Nautica Malibu Triathlon held at Zuma Beach in Malibu, California. The Race raised funds for children\'s Hospital Los Angeles. She won that race for women\'s K-Swiss team. On 27 September 2008, Kournikova played exhibition mixed doubles matches in Charlotte, North Carolina, partnering with Tim Wilkison and Karel Nováček. Kournikova and Wilkison defeated Jimmy Arias and Chanda Rubin, and then Kournikova and Novacek defeated Rubin and Wilkison.
On 12 October 2008, Anna Kournikova played one exhibition match for the annual charity event, hosted by Billie Jean King and Elton John, and raised more than \$400,000 for the Elton John AIDS Foundation and Atlanta AIDS Partnership Fund. She played doubles with Andy Roddick (they were coached by David Chang) versus Martina Navratilova and Jesse Levine (coached by Billie Jean King); Kournikova and Roddick won.
Kournikova was one of \"four former world No. 1 players\" who participated in \"Legendary Night\", held on 2 May 2009, at the Turning Stone Event Center in Verona, New York, the others being John McEnroe (who had been No. 1 in both singles and doubles), Tracy Austin and Jim Courier (both of whom who had been No. 1 in singles but not doubles). The exhibition included a mixed doubles match in which McEnroe and Kournikova defeated Courier and Austin.
In 2008, she was named a spokesperson for K-Swiss. In 2005, Kournikova stated that if she were 100% fit, she would like to come back and compete again.
In June 2010, Kournikova reunited with her doubles partner Martina Hingis to participate in competitive tennis for the first time in seven years in the Invitational Ladies Doubles event at Wimbledon. On 29 June 2010 they defeated the British pair Samantha Smith and Anne Hobbs.
## Playing style {#playing_style}
Kournikova plays right-handed with a two-handed backhand. She is a great player at the net. She can hit forceful groundstrokes and also drop shots.
Her playing style fits the profile for a doubles player, and is complemented by her height. She has been compared to such doubles specialists as Pam Shriver and Peter Fleming.
## Personal life {#personal_life}
Kournikova was in a relationship with fellow Russian, Pavel Bure, an NHL ice hockey player. The two met in 1999, when Kournikova was still linked to Bure\'s former Russian teammate Sergei Fedorov. Bure and Kournikova were reported to have been engaged in 2000 after a reporter took a photo of them together in a Florida restaurant where Bure supposedly asked Kournikova to marry him. As the story made headlines in Russia, where they were both heavily followed in the media as celebrities, Bure and Kournikova both denied any engagement. Kournikova, 10 years younger than Bure, was 18 years old at the time.
Fedorov claimed that he and Kournikova were married in 2001, and divorced in 2003. Kournikova\'s representatives deny any marriage to Fedorov; however, Fedorov\'s agent Pat Brisson claims that although he does not know when they got married, he knew \"Fedorov was married\".
Kournikova started dating singer Enrique Iglesias in late 2001 after she had appeared in his music video for \"Escape\". The couple have three children together, fraternal twins, a son and daughter, born on 16 December 2017, and another daughter born on 30 January 2020.
It was reported in 2010 that Kournikova had become an American citizen.
## Media publicity {#media_publicity}
In 2000, Kournikova became the new face for Berlei\'s shock absorber sports bras, and appeared in the \"only the ball should bounce\" billboard campaign. Following that, she was cast by the Farrelly brothers for a minor role in the 2000 film *Me, Myself & Irene* starring Jim Carrey and Renée Zellweger. Photographs of her have appeared on covers of various publications, including men\'s magazines, such as one in the much-publicized 2004 *Sports Illustrated Swimsuit Issue*, where she posed in bikinis and swimsuits, as well as in *FHM* and *Maxim*.
Kournikova was named one of *People*{{\'}}s 50 Most Beautiful People in 1998 and was voted \"hottest female athlete\" on ESPN.com. In 2002, she also placed first in *FHM\'s 100 Sexiest Women in the World* in US and UK editions. By contrast, ESPN -- citing the degree of hype as compared to actual accomplishments as a singles player -- ranked Kournikova 18th in its \"25 Biggest Sports Flops of the Past 25 Years\". Kournikova was also ranked No. 1 in the ESPN Classic series \"Who\'s number 1?\" when the series featured sport\'s most overrated athletes.
In 2002, *Penthouse* magazine published paparazzi photographs that purported to show Kournikova sunbathing topless on a Florida beach. Stating that the images were not of her, Kournikova sued the magazine\'s parent company, seeking damages of \$10 million. The woman featured in the images, Judith E. Soltesz-Benetton, daughter-in-law of fashion designer Luciano Benetton, also sued for \$10 million, saying the photos had been taken without her knowledge seven years earlier. *Penthouse* issued apologies to both women, withdrew the issue from further distribution, and settled the cases out of court.
She continued to be the most searched athlete on the Internet through 2008 even though she had retired from the professional tennis circuit years earlier. After slipping from first to sixth among athletes in 2009, she moved back up to third place among athletes in terms of search popularity in 2010.
In October 2010, Kournikova headed to NBC\'s *The Biggest Loser* where she led the contestants in a tennis-workout challenge. In May 2011, it was announced that Kournikova would join *The Biggest Loser* as a regular celebrity trainer in season 12. She did not return for season 13.
## Legacy and influence on popular culture {#legacy_and_influence_on_popular_culture}
- A variation of a White Russian made with skim milk is known as an Anna Kournikova.
- A video game featuring Kournikova\'s licensed appearance, titled *Anna Kournikova\'s Smash Court Tennis*, was developed by Namco and released for the PlayStation in Japan and Europe in November 1998.
- A computer virus named after her spread worldwide beginning on 12 February 2001 infecting computers through email in a matter of hours.
## Career statistics and awards {#career_statistics_and_awards}
### Doubles performance timeline {#doubles_performance_timeline}
Tournament 1995 1996 1997 1998 1999 2000 2001 2002 2003 SR W--L
---------------------------- ------ ------ ------ ------ ------- ------- ------ ------- ------ -------- --------
**Grand Slam tournaments**
Australian Open A A 1R 2R **W** SF QF **W** 3R 2 / 7 22--5
French Open A A 3R SF F 3R A A A 0 / 4 13--4
Wimbledon A A 2R A A SF A SF A 0 / 3 9--3
US Open A QF 3R 2R A 2R A QF A 0 / 5 10--5
Win--loss 0--0 3--1 5--4 6--3 11--1 11--4 3--1 13--2 2--1 2 / 19 54--17
**Year-end championship**
Tour Championships A A A QF **W** **W** A A A 2 / 3 6--1
**Career statistics**
Year-end ranking 70 40 10 **1** 4 26 11 176
### Grand Slam tournament finals {#grand_slam_tournament_finals}
#### Doubles: 3 (2--1) {#doubles_3_21}
+--------+------+---------------------+---------+----------------+--------------------------------------------------------+--------------------------+
| Result | Year | Championship | Surface | Partner | Opponents | Score |
+========+======+=====================+=========+================+========================================================+==========================+
| | | | | | | |
+--------+------+---------------------+---------+----------------+--------------------------------------------------------+--------------------------+
| Win | 1999 | Australian Open | Hard | Martina Hingis | Lindsay Davenport\ | 7--5, 6--3 |
| | | | | | Natasha Zvereva | |
+--------+------+---------------------+---------+----------------+--------------------------------------------------------+--------------------------+
| | | | | | | |
+--------+------+---------------------+---------+----------------+--------------------------------------------------------+--------------------------+
| Loss | 1999 | French Open | Clay | Martina Hingis | Serena Williams\ | 3--6, 7--6^(7--2)^, 6--8 |
| | | | | | `{{flagicon|USA}}`{=mediawiki} Venus Williams | |
+--------+------+---------------------+---------+----------------+--------------------------------------------------------+--------------------------+
| | | | | | | |
+--------+------+---------------------+---------+----------------+--------------------------------------------------------+--------------------------+
| Win | 2002 | Australian Open (2) | Hard | Martina Hingis | Daniela Hantuchová\ | 6--2, 6--7^(4--7)^, 6--1 |
| | | | | | `{{flagicon|ESP}}`{=mediawiki} Arantxa Sánchez Vicario | |
+--------+------+---------------------+---------+----------------+--------------------------------------------------------+--------------------------+
#### Mixed doubles: 2 (0--2) {#mixed_doubles_2_02}
+--------+------+--------------+---------+----------------+--------------------------------------------------------+------------------+
| Result | Year | Championship | Surface | Partner | Opponents | Score |
+========+======+==============+=========+================+========================================================+==================+
| | | | | | | |
+--------+------+--------------+---------+----------------+--------------------------------------------------------+------------------+
| Loss | 1999 | Wimbledon | Grass | Jonas Björkman | Leander Paes\ | 4--6, 6--3, 3--6 |
| | | | | | `{{flagicon|USA}}`{=mediawiki} Lisa Raymond | |
+--------+------+--------------+---------+----------------+--------------------------------------------------------+------------------+
| | | | | | | |
+--------+------+--------------+---------+----------------+--------------------------------------------------------+------------------+
| Loss | 2000 | US Open | Hard | Max Mirnyi | Jared Palmer\ | 4--6, 3--6 |
| | | | | | `{{flagicon|ESP}}`{=mediawiki} Arantxa Sánchez Vicario | |
+--------+------+--------------+---------+----------------+--------------------------------------------------------+------------------+
### Awards
- 1996: WTA Newcomer of the Year
- 1999: WTA Doubles Team of the Year (with Martina Hingis)
## Books
- *Anna Kournikova* by Susan Holden (2001) (`{{ISBN|978-1-84222-416-8}}`{=mediawiki} / `{{ISBN|978-1-84222-416-8}}`{=mediawiki})
- *Anna Kournikova* by Connie Berman (2001) (Women Who Win) (`{{ISBN|978-0-7910-6529-7}}`{=mediawiki} / `{{ISBN|978-0-7910-6529-7}}`{=mediawiki})
| 2025-08-01T00:00:00 |
892 |
Alfons Maria Jakob
|
**Alfons Maria Jakob** (2 July 1884 -- 17 October 1931) was a German neurologist who worked in the field of neuropathology.
He was born in Aschaffenburg, Bavaria and educated in medicine at the universities of Munich, Berlin, and Strasbourg, where he received his doctorate in 1908. During the following year, he began clinical work under the psychiatrist Emil Kraepelin and did laboratory work with Franz Nissl and Alois Alzheimer in Munich.
In 1911, by way of an invitation from Wilhelm Weygandt, he relocated to Hamburg, where he worked with Theodor Kaes and eventually became head of the laboratory of anatomical pathology at the psychiatric State Hospital Hamburg-Friedrichsberg. Following the death of Kaes in 1913, Jakob succeeded him as prosector. During World War I he served as an army physician in Belgium, and afterwards returned to Hamburg. In 1919, he obtained his habilitation for neurology and in 1924 became a professor of neurology. Under Jakob\'s guidance the department grew rapidly. He made significant contributions to knowledge on concussion and secondary nerve degeneration and became a doyen of neuropathology.
Jakob was the author of five monographs and nearly 80 scientific papers. His neuropathological research contributed greatly to the delineation of several diseases, including multiple sclerosis and Friedreich\'s ataxia. He first recognised and described Alper\'s disease and Creutzfeldt--Jakob disease (named along with Munich neuropathologist Hans Gerhard Creutzfeldt). He gained experience in neurosyphilis, having a 200-bed ward devoted entirely to that disorder. Jakob made a lecture tour of the United States (1924) and South America (1928), of which, he wrote a paper on the neuropathology of yellow fever.
He suffered from chronic osteomyelitis for the last seven years of his life. This eventually caused a retroperitoneal abscess and paralytic ileus from which he died following operation.
## Associated eponym {#associated_eponym}
- Creutzfeldt--Jakob disease: A very rare and incurable degenerative neurological disease. It is the most common form of transmissible spongiform encephalopathies caused by prions. Eponym introduced by Walther Spielmeyer in 1922.
| 2025-08-01T00:00:00 |
903 |
Arable land
|
upright=1.25\|thumb\| Modern mechanised agriculture permits large fields like this one in Dorset, England **Arable land** (from the *arabilis\]\]*, \"able to be ploughed\") is any land capable of being ploughed and used to grow crops. Alternatively, for the purposes of agricultural statistics, the term often has a more precise definition: `{{blockquote|Arable land is the land under temporary agricultural crops (multiple-cropped areas are counted only once), temporary [[meadow]]s for mowing or [[pasture]], land under [[market garden|market]] and [[kitchen garden]]s and land temporarily [[fallow]] (less than five years). The abandoned land resulting from [[shifting cultivation]] is not included in this category. Data for 'Arable land' are not meant to indicate the amount of land that is potentially cultivable.<ref>FAOSTAT. [Statistical database of the Food and Agriculture Organization of the United Nations] Glossary. http://faostat3.fao.org/{{Webarchive|url=https://web.archive.org/web/20150601235945/http://faostat3.fao.org/mes/glossary/E |date= 1 June 2015 }}</ref>}}`{=mediawiki} A more concise definition appearing in the Eurostat glossary similarly refers to actual rather than potential uses: \"land worked (ploughed or tilled) regularly, generally under a system of crop rotation\". In Britain, arable land has traditionally been contrasted with pasturable land such as heaths, which could be used for sheep-rearing but not as farmland.
Arable land is vulnerable to land degradation and some types of un-arable land can be enriched to create useful land. Climate change and biodiversity loss are driving pressure on arable land.
## By country {#by_country}
thumb\|upright=1.8\|Share of land area used for arable agriculture, OWID Further information: Land use statistics by country According to the Food and Agriculture Organization of the United Nations, in 2013, the world\'s arable land amounted to 1.407 billion hectares, out of a total of 4.924 billion hectares of land used for agriculture.
+--------------------------------------------------------------------------------+
| Rank Country or region 2015 2016 2017 2018 2019 |
| ------ ------------------- --------- --------- --------- --------- --------- |
| 1 156,645 157,191 157,737 157,737 157,737 |
| 2 156,413 156,317 156,317 156,317 156,067 |
| 3 121,649 121,649 121,649 121,649 121,649 |
| 4 119,593 119,512 119,477 119,475 119,474 |
| 5 54,518 55,140 55,762 55,762 55,762 |
| 6 38,282 38,530 38,509 38,690 38,648 |
| 7 34,000 34,000 34,000 34,000 34,000 |
| 8 32,775 32,776 32,773 32,889 32,924 |
| 9 36,688 35,337 33,985 32,633 32,633 |
| 10 31,090 30,057 30,752 30,974 30,573 |
| |
| |
| : Arable land area (1000 ha) |
+--------------------------------------------------------------------------------+
### Arable land (hectares per person) {#arable_land_hectares_per_person}
upright=1.35\|thumb\|Fields in the region of Záhorie in Western Slovakia thumb\|right\|upright=1.35\|A field of sunflowers in Cardejón, Spain
Country Name 2013
-------------------------------- -------
Afghanistan 0.254
Albania 0.213
Algeria 0.196
American Samoa 0.054
Andorra 0.038
Angola 0.209
Antigua and Barbuda 0.044
Argentina 0.933
Armenia 0.150
Aruba 0.019
Australia 1.999
Austria 0.160
Azerbaijan 0.204
Bahamas, The 0.021
Bahrain 0.001
Bangladesh 0.049
Barbados 0.039
Belarus 0.589
Belgium 0.073
Belize 0.227
Benin 0.262
Bermuda 0.005
Bhutan 0.133
Bolivia 0.427
Bosnia and Herzegovina 0.264
Botswana 0.125
Brazil 0.372
British Virgin Islands 0.034
Brunei Darussalam 0.012
Bulgaria 0.479
Burkina Faso 0.363
Burundi 0.115
Cabo Verde 0.108
Cambodia 0.275
Cameroon 0.279
Canada 1.306
Cayman Islands 0.003
Central African Republic 0.382
Chad 0.373
Channel Islands 0.026
Chile 0.074
China 0.078
Colombia 0.036
Comoros 0.086
Congo, Dem. Rep. 0.098
Congo, Rep. 0.125
Costa Rica 0.049
Côte d\'Ivoire 0.134
Croatia 0.206
Cuba 0.278
Curaçao
Cyprus 0.070
Czech Republic 0.299
Denmark 0.429
Djibouti 0.002
Dominica 0.083
Dominican Republic 0.078
Ecuador 0.076
Egypt, Arab Rep. 0.031
El Salvador 0.120
Equatorial Guinea 0.151
Eritrea
Estonia 0.480
Ethiopia 0.160
Faroe Islands 0.062
Fiji 0.187
Finland 0.409
France 0.277
French Polynesia 0.009
Gabon 0.197
Gambia, The 0.236
Georgia 0.119
Germany 0.145
Ghana 0.180
Gibraltar
Greece 0.232
Greenland 0.016
Grenada 0.028
Guam 0.006
Guatemala 0.064
Guinea 0.259
Guinea-Bissau 0.171
Guyana 0.552
Haiti 0.103
Honduras 0.130
Hong Kong SAR, China 0.000
Hungary 0.445
Iceland 0.374
India 0.123
Indonesia 0.094
Iran, Islamic Rep. 0.193
Iraq 0.147
Ireland 0.242
Isle of Man 0.253
Israel 0.035
Italy 0.113
Jamaica 0.044
Japan 0.033
Jordan 0.032
Kazakhstan 1.726
Kenya 0.133
Kiribati 0.018
Korea, Dem. People\'s Rep. 0.094
Korea, Rep. 0.030
Kosovo
Kuwait 0.003
Kyrgyz Republic 0.223
Lao PDR 0.226
Latvia 0.600
Lebanon 0.025
Lesotho 0.119
Liberia 0.116
Libya 0.274
Liechtenstein 0.070
Lithuania 0.774
Luxembourg 0.115
Macao SAR, China
Macedonia, FYR 0.199
Madagascar 0.153
Malawi 0.235
Malaysia 0.032
Maldives 0.010
Mali 0.386
Malta 0.021
Marshall Islands 0.038
Mauritania 0.116
Mauritius 0.060
Mexico 0.186
Micronesia, Fed. Sts. 0.019
Moldova 0.510
Monaco
Mongolia 0.198
Montenegro 0.013
Morocco 0.240
Mozambique 0.213
Myanmar 0.203
Namibia 0.341
Nauru
Nepal 0.076
Netherlands 0.062
New Caledonia 0.024
New Zealand 0.123
Nicaragua 0.253
Niger 0.866
Nigeria 0.197
Northern Mariana Islands 0.019
Norway 0.159
Oman 0.010
Pakistan 0.168
Palau 0.048
Panama 0.148
Papua New Guinea 0.041
Paraguay 0.696
Peru 0.136
Philippines 0.057
Poland 0.284
Portugal 0.107
Puerto Rico 0.017
Qatar 0.007
Romania 0.438
Russian Federation 0.852
Rwanda 0.107
Samoa 0.042
San Marino 0.032
São Tomé and Príncipe 0.048
Saudi Arabia 0.102
Senegal 0.229
Serbia 0.460
Seychelles 0.001
Sierra Leone 0.256
Singapore 0.000
Sint Maarten (Dutch part)
Slovak Republic 0.258
Slovenia 0.085
Solomon Islands 0.036
Somalia 0.107
South Africa 0.235
South Sudan
Spain 0.270
Sri Lanka 0.063
St. Kitts and Nevis 0.092
St. Lucia 0.016
St. Martin (French part)
St. Vincent and the Grenadines 0.046
Sudan 0.345
Suriname 0.112
Swaziland 0.140
Sweden 0.270
Switzerland 0.050
Syrian Arab Republic 0.241
Tajikistan 0.106
Tanzania 0.269
Thailand 0.249
Timor-Leste 0.131
Togo 0.382
Tonga 0.152
Trinidad and Tobago 0.019
Tunisia 0.262
Turkey 0.270
Turkmenistan 0.370
Turks and Caicos Islands 0.030
Tuvalu
Uganda 0.189
Ukraine 0.715
United Arab Emirates 0.004
United Kingdom 0.098
United States 0.480
Uruguay 0.682
Uzbekistan 0.145
Vanuatu 0.079
Venezuela, RB 0.089
Vietnam 0.071
Virgin Islands (US) 0.010
West Bank and Gaza 0.011
Yemen, Rep. 0.049
Zambia 0.243
Zimbabwe 0.268
: `{{nowrap|Arable land (hectares per person)<ref name="faostat_old" />}}`{=mediawiki}
## Non-arable land {#non_arable_land}
thumb\|upright=1.25\|Water buffalo ploughing rice fields near Salatiga, Central Java, Indonesia thumb\|upright=1.25\|A pasture in the East Riding of Yorkshire in England Agricultural land that is not arable according to the FAO definition above includes:
- Meadows and pastures`{{snd}}`{=mediawiki}land used as pasture and grazed range, and those natural grasslands and sedge meadows that are used for hay production in some regions.
- Permanent crop`{{snd}}`{=mediawiki}land that produces crops from woody vegetation, e.g. orchard land, vineyards, coffee plantations, rubber plantations, and land producing nut trees;
Other non-arable land includes land that is not suitable for any agricultural use. Land that is not arable, in the sense of lacking capability or suitability for cultivation for crop production, has one or more limitations`{{snd}}`{=mediawiki}a lack of sufficient freshwater for irrigation, stoniness, steepness, adverse climate, excessive wetness with the impracticality of drainage, excessive salts, or a combination of these, among others. Although such limitations may preclude cultivation, and some will in some cases preclude any agricultural use, large areas unsuitable for cultivation may still be agriculturally productive. For example, United States NRCS statistics indicate that about 59 percent of US non-federal pasture and unforested rangeland is unsuitable for cultivation, yet such land has value for grazing of livestock. In British Columbia, Canada, 41 percent of the provincial Agricultural Land Reserve area is unsuitable for the production of cultivated crops, but is suitable for uncultivated production of forage usable by grazing livestock. Similar examples can be found in many rangeland areas elsewhere.
## Changes in arability {#changes_in_arability}
### Land conversion {#land_conversion}
Land incapable of being cultivated for the production of crops can sometimes be converted to arable land. New arable land makes more food and can reduce starvation. This outcome also makes a country more self-sufficient and politically independent, because food importation is reduced. Making non-arable land arable often involves digging new irrigation canals and new wells, aqueducts, desalination plants, planting trees for shade in the desert, hydroponics, fertilizer, nitrogen fertilizer, pesticides, reverse osmosis water processors, PET film insulation or other insulation against heat and cold, digging ditches and hills for protection against the wind, and installing greenhouses with internal light and heat for protection against the cold outside and to provide light in cloudy areas. Such modifications are often prohibitively expensive. An alternative is the seawater greenhouse, which desalinates water through evaporation and condensation using solar energy as the only energy input. This technology is optimized to grow crops on desert land close to the sea.
The use of artifices does not make the land arable. Rock still remains rock, and shallow`{{snd}}`{=mediawiki}less than 6 feet`{{snd}}`{=mediawiki}turnable soil is still not considered toilable. The use of artifice is an open-air non-recycled water hydroponics relationship.`{{clarify |date=November 2019 |reason=Unclear what this sentence means}}`{=mediawiki} The below described circumstances are not in perspective, have limited duration, and have a tendency to accumulate trace materials in soil that either there or elsewhere cause deoxygenation. The use of vast amounts of fertilizer may have unintended consequences for the environment by devastating rivers, waterways, and river endings through the accumulation of non-degradable toxins and nitrogen-bearing molecules that remove oxygen and cause non-aerobic processes to form.
Examples of infertile non-arable land being turned into fertile arable land include:
- Aran Islands: These islands off the west coast of Ireland (not to be confused with the Isle of Arran in Scotland\'s Firth of Clyde) were unsuitable for arable farming because they were too rocky. The people covered the islands with a shallow layer of seaweed and sand from the ocean. Today,`{{When|date=July 2021}}`{=mediawiki} crops are grown there, even though the islands are still considered non-arable.
- Israel: The construction of desalination plants along Israel\'s coast allowed agriculture in some areas that were formerly desert. The desalination plants, which remove the salt from ocean water, have produced a new source of water for farming, drinking, and washing.
- Slash and burn agriculture uses nutrients from the wood ash, but these are exhausted within a few years.
- Terra preta, fertile tropical soils produced by adding charcoal.
### Land degradation {#land_degradation}
#### Examples
Examples of fertile arable land being turned into infertile land include:
- Droughts such as the \"Dust Bowl\" of the Great Depression in the US turned farmland into desert.
- Each year, arable land is lost due to desertification and human-induced erosion. Improper irrigation of farmland can wick the sodium, calcium, and magnesium from the soil and water to the surface. This process steadily concentrates salt in the root zone, decreasing productivity for crops that are not salt-tolerant.
- Rainforest deforestation: The fertile tropical forests are converted into infertile desert land. For example, Madagascar\'s central highland plateau has become virtually totally barren (about ten percent of the country) as a result of slash-and-burn deforestation, an element of shifting cultivation practiced by many natives.
- According to a study published in the journal, *Science*, toxic heavy metals can contaminate arable land.
| 2025-08-01T00:00:00 |
905 |
Advanced Chemistry
|
**Advanced Chemistry** is a German hip hop group from Heidelberg in Baden-Württemberg, South Germany. Advanced Chemistry was founded in 1987 by Toni L, Linguist, Gee-One, DJ Mike MD (Mike Dippon) and MC Torch. Each member of the group holds German citizenship, and Toni L, Linguist, and Torch are of Italian, Ghanaian, and Haitian backgrounds, respectively.
Influenced by North American socially conscious rap and the Native tongues movement, Advanced Chemistry is regarded as one of the main pioneers in German hip hop. They were one of the first groups to rap in German (although their name is in English). Furthermore, their songs tackled controversial social and political issues, distinguishing them from early German hip hop group \"Die Fantastischen Vier\" (The Fantastic Four), which had a more light-hearted, playful, party image.
## Career
Advanced Chemistry frequently rapped about their lives and experiences as children of immigrants, exposing the marginalization experienced by most ethnic minorities in Germany, and the feelings of frustration and resentment that being denied a German identity can cause. The song \"Fremd im eigenen Land\" (Foreign in your own nation) was released by Advanced Chemistry in November 1992. The single became a staple in the German hip hop scene. It made a strong statement about the status of immigrants throughout Germany, as the group was composed of multi-national and multi-racial members. The video shows several members brandishing their German passports as a demonstration of their German citizenship to skeptical and unaccepting \'ethnic\' Germans.
This idea of national identity is important, as many rap artists in Germany have been of foreign origin. These so-called *Gastarbeiter* (guest workers) children saw breakdance, graffiti, rap music, and hip hop culture as a means of expressing themselves. Since the release of \"Fremd im eigenen Land\", many other German-language rappers have also tried to confront anti-immigrant ideas and develop themes of citizenship. However, though many ethnic minority youth in Germany find these German identity themes appealing, others view the desire of immigrants to be seen as German negatively, and they have actively sought to revive and recreate concepts of identity in connection to traditional ethnic origins.
Advanced Chemistry helped to found the German chapter of the Zulu nation.
The rivalry between Advanced Chemistry and Die Fantastischen Vier has served to highlight a dichotomy in the routes that hip hop has taken in becoming a part of the German soundscape. While Die Fantastischen Vier may be said to view hip hop primarily as an aesthetic art form, Advanced Chemistry understand hip hop as being inextricably linked to the social and political circumstances under which it is created. For Advanced Chemistry, hip hop is a "vehicle of general human emancipation". In their undertaking of social and political issues, the band introduced the term \"Afro-German\" into the context of German hip hop, and the theme of race is highlighted in much of their music.
With the release of the single "Fremd im eigenen Land", Advanced Chemistry separated itself from the rest of the rap being produced in Germany. This single was the first of its kind to go beyond simply imitating US rap and addressed the current issues of the time. Fremd im eigenen Land which translates to "foreign in my own country" dealt with the widespread racism that non-white German citizens faced. This change from simple imitation to political commentary was the start of German identification with rap. The sound of "Fremd im eigenen Land" was influenced by the \'wall of noise\' created by Public Enemy\'s producers, The Bomb Squad.
After the reunification of Germany, an abundance of anti-immigrant sentiment emerged, as well as attacks on the homes of refugees in the early 1990s. Advanced Chemistry came to prominence in the wake of these actions because of their pro-multicultural society stance in their music. Advanced Chemistry\'s attitudes revolve around their attempts to create a distinct \"Germanness\" in hip hop, as opposed to imitating American hip hop as other groups had done. Torch has said, \"What the Americans do is exotic for us because we don\'t live like they do. What they do seems to be more interesting and newer. But not for me. For me it\'s more exciting to experience my fellow Germans in new contexts\...For me, it\'s interesting to see what the kids try to do that\'s different from what I know.\" Advanced Chemistry were the first to use the term \"Afro-German\" in a hip hop context. This was part of the pro-immigrant political message they sent via their music.
While Advanced Chemistry\'s use of the German language in their rap allows them to make claims to authenticity and true German heritage, bolstering pro-immigration sentiment, their style can also be problematic for immigrant notions of any real ethnic roots. Indeed, part of the Turkish ethnic minority of Frankfurt views Advanced Chemistry\'s appeal to the German image as a \"symbolic betrayal of the right of ethnic minorities to \'roots\' or to any expression of cultural heritage.\" In this sense, their rap represents a complex social discourse internal to the German soundscape in which they attempt to negotiate immigrant assimilation into a xenophobic German culture with the maintenance of their own separate cultural traditions. It is quite possibly the feelings of alienation from the pure-blooded German demographic that drive Advanced Chemistry to attack nationalistic ideologies by asserting their \"Germanness\" as a group composed primarily of ethnic others. The response to this pseudo-German authenticity can be seen in what Andy Bennett refers to as \"alternative forms of local hip hop culture which actively seek to rediscover and, in many cases, reconstruct notions of identity tied to cultural roots.\" These alternative local hip hop cultures include oriental hip hop, the members of which cling to their Turkish heritage and are confused by Advanced Chemistry\'s elicitation of a German identity politics to which they technically do not belong. This cultural binary illustrates that rap has taken different routes in Germany and that, even among an already isolated immigrant population, there is still disunity and, especially, disagreement on the relative importance of assimilation versus cultural defiance. According to German hip hop enthusiast 9@home, Advanced Chemistry is part of a \"hip-hop movement \[which\] took a clear stance for the minorities and against the \[marginalization\] of immigrants who\...might be German on paper, but not in real life,\" which speaks to the group\'s hope of actually being recognized as German citizens and not foreigners, despite their various other ethnic and cultural ties.
## Influences
Advanced Chemistry\'s work was rooted in German history and the country\'s specific political realities. However, they also drew inspiration from African-American hip-hop acts like A Tribe Called Quest and Public Enemy, who had helped bring a soulful sound and political consciousness to American hip-hop. One member, Torch, later explicitly listed his references on his solo song \"Als (When I Was in School):\" \"My favorite subject, which was quickly discovered poetry in load Poets, awakens the intellect or policy at Chuck D I\'ll never forget the lyrics by Public Enemy.\" Torch goes on to list other American rappers like Biz Markie, Big Daddy Kane and Dr. Dre as influences.
## Discography
- 1992 - \"Fremd im eigenen Land\" (12\"/MCD, MZEE)
- 1993 - \"Welcher Pfad führt zur Geschichte\" (12\"/MCD, MZEE)
- 1994 - \"Operation § 3\" (12\"/MCD)
- 1994 - \"Dir fehlt der Funk!\" (12\"/MCD)
- 1995 - *Advanced Chemistry* (2xLP/CD)
| 2025-08-01T00:00:00 |
910 |
Arne Kaijser
|
**Arne Kaijser** (born 1950) is a professor emeritus of history of technology at the KTH Royal Institute of Technology in Stockholm, and a former president of the Society for the History of Technology.
Kaijser has published two books in Swedish: *Stadens ljus. Etableringen av de första svenska gasverken* and *I fädrens spår. Den svenska infrastrukturens historiska utveckling och framtida utmaningar*, and has co-edited several anthologies. Kaijser is a member of the Royal Swedish Academy of Engineering Sciences since 2007 and also a member of the editorial board of two scientific journals: *Journal of Urban Technology* and *Centaurus*. Lately, he has been occupied with the history of Large Technical Systems.
| 2025-08-01T00:00:00 |
911 |
Archipelago
|
thumb\|upright=1.6\|The Indonesian Archipelago, located in Asia and Oceania, is the largest archipelagic state in the world. An **archipelago** (`{{IPAc-en|ˌ|ɑːr|k|ə|ˈ|p|ɛ|l|ə|ɡ|oʊ|audio=en-us-archipelago.ogg}}`{=mediawiki} `{{respell|AR|kə|PEL|ə|goh}}`{=mediawiki}), sometimes called an **island group** or **island chain**, is a chain, cluster, or collection of islands. An archipelago may be in an ocean, a sea, or a smaller body of water. Example archipelagos include the Aegean Islands (the origin of the term), the Canadian Arctic Archipelago, the Stockholm Archipelago, the Malay Archipelago (which includes the Indonesian and Philippine Archipelagos), the Lucayan (Bahamian) Archipelago, the Japanese archipelago, and the Hawaiian Archipelago.
## Etymology
The word *archipelago* is derived from the Italian *arcipelago*, used as a proper name for the Aegean Sea, itself perhaps a deformation of the Greek Αιγαίον Πέλαγος. Later, usage shifted to refer to the Aegean Islands (since the sea has a large number of islands). The erudite paretymology, deriving the word from Ancient Greek ἄρχι-(*arkhi-*, \"chief\") and πέλαγος (*pélagos*, \"sea\"), proposed by Buondelmonti, can still be found.
## Geographic types {#geographic_types}
Archipelagos may be found isolated in large amounts of water or neighboring a large land mass. For example, Scotland has more than 700 islands surrounding its mainland, which form an archipelago.
Depending on their geological origin, islands forming archipelagos can be referred to as *oceanic islands*, *continental fragments*, or *continental islands*.
### Oceanic islands {#oceanic_islands}
Oceanic islands are formed by volcanoes erupting from the ocean floor. The Hawaiian Islands and Galapagos Islands in the Pacific, and Mascarene Islands in the south Indian Ocean are examples.
### Continental fragments {#continental_fragments}
Continental fragments are islands that were once part of a continent, and became separated due to natural disasters. The fragments may also be formed by moving glaciers which cut out land, which then fills with water. The Farallon Islands off the coast of California are examples of continental islands.
### Continental Islands {#continental_islands}
Continental islands are islands that were once part of a continent and still sit on the continental shelf, which is the edge of a continent that lies under the ocean. The islands of the Inside Passage off the coast of British Columbia and the Canadian Arctic Archipelago are examples.
### Artificial archipelagos {#artificial_archipelagos}
Artificial archipelagos have been created in various countries for different purposes. Palm Islands and The World Islands in Dubai were or are being created for leisure and tourism purposes. Marker Wadden in the Netherlands is being built as a conservation area for birds and other wildlife.
## Superlatives
The largest archipelago in the world by number of islands is the Archipelago Sea, which is part of Finland. There are approximately 40,000 islands, mostly uninhabited.
The largest archipelagic state in the world by area, and by population, is Indonesia.
| 2025-08-01T00:00:00 |
921 |
Angst
|
`{{Emotion}}`{=mediawiki}
**Angst** is a feeling of anxiety, apprehension, or insecurity. *Anguish* is its Latinate equivalent, and the words *anxious* and *anxiety* are of similar origin.
## Etymology
The word *angst* was introduced into English from the Danish, Norwegian, and Dutch word *angst* and the German word *Angst*. It is attested since the 19th century in English translations of the works of Søren Kierkegaard and Sigmund Freud. It is used in English to describe an intense feeling of apprehension, anxiety, or inner turmoil.
In other languages (with words from the Latin *pavor* for \"fear\" or \"panic\"), the derived words differ in meaning; for example, as in the French *anxiété* and *peur*. The word *angst* has existed in German since the 8th century, from the Proto-Indo-European root *anghu-*, \"restraint\" from which Old High German *angust* developed. It is pre-cognate with the Latin *angustia*, \"tensity, tightness\" and `{{wikt-lang|la|angor}}`{=mediawiki}, \"choking, clogging\"; compare to the Ancient Greek `{{wikt-lang|grc|ἄγχω}}`{=mediawiki} (*ánkhō*) \"strangle\". It entered English in the 19th century as a technical term used in psychiatry, though earlier cognates existed, such as *ange*.
## Existentialism
In existentialist philosophy, the term *angst* carries a specific conceptual meaning. The use of the term was first attributed to Danish philosopher Søren Kierkegaard (1813--1855). In *The Concept of Anxiety* (originally translated as *The Concept of Dread*), Kierkegaard used the word *Angest* (in common Danish, *angst*, meaning \"dread\" or \"anxiety\") to describe a profound and deep-seated condition. Where non-human animals are guided solely by instinct, said Kierkegaard, human beings enjoy a freedom of choice that we find both appealing and terrifying. It is the anxiety of understanding of being free when considering undefined possibilities of one\'s life and the immense responsibility of having the power of choice over them. Kierkegaard\'s concept of angst reappeared in the works of existentialist philosophers who followed, such as Friedrich Nietzsche, Jean-Paul Sartre, and Martin Heidegger, each of whom developed the idea further in individual ways. While Kierkegaard\'s angst referred mainly to ambiguous feelings about moral freedom within a religious personal belief system, later existentialists discussed conflicts of personal principles, cultural norms, and existential despair.
## Music
Existential angst makes its appearance in classical musical composition in the early twentieth century as a result of both philosophical developments and as a reflection of the war-torn times. Notable composers whose works are often linked with the concept include Gustav Mahler, Richard Strauss (operas **Elektra\]\]** and **Salome\]\]**), Claude Debussy (opera **Pelléas et Mélisande\]\]**, ballet *Jeux*), Jean Sibelius (especially the Fourth Symphony), Arnold Schoenberg (*A Survivor from Warsaw*), Alban Berg, Francis Poulenc (opera *Dialogues of the Carmelites*), Dmitri Shostakovich (opera *Lady Macbeth of Mtsensk*, symphonies and chamber music), Béla Bartók (opera *Bluebeard\'s Castle*), and Krzysztof Penderecki (especially *Threnody to the Victims of Hiroshima*).
Angst began to be discussed in reference to popular music in the mid- to late 1950s, amid widespread concerns over international tensions and nuclear proliferation. Jeff Nuttall\'s book *Bomb Culture* (1968) traced angst in popular culture to Hiroshima. Dread was expressed in works of folk rock such as Bob Dylan\'s \"Masters of War\" (1963) and \"A Hard Rain\'s a-Gonna Fall\". The term often makes an appearance in reference to punk rock, grunge, nu metal, and works of emo where expressions of melancholy, existential despair, or nihilism predominate.
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A. A. Milne
|
**Alan Alexander Milne** (`{{IPAc-en|m|ɪ|l|n|audio=LL-Q1860 (eng)-Naomi Persephone Amethyst (NaomiAmethyst)-Milne.wav}}`{=mediawiki}; 18 January 1882 -- 31 January 1956) was an English writer best known for his books about the teddy bear Winnie-the-Pooh, as well as children\'s poetry. Milne was primarily a playwright before the huge success of Winnie-the-Pooh overshadowed his previous work. He served as a lieutenant in the Royal Warwickshire Regiment in the First World War and as a captain in the Home Guard in the Second World War.
Milne was the father of bookseller Christopher Robin Milne, upon whom the character Christopher Robin is based. It was during a visit to London Zoo, where Christopher became enamoured with the tame and amiable bear Winnipeg, that Milne was inspired to write the story of Winnie-the-Pooh for his son. Milne bequeathed the original manuscripts of the Winnie-the-Pooh stories to the Wren Library at Trinity College, Cambridge, his alma mater.
## Early life and military career {#early_life_and_military_career}
Alan Alexander Milne was born in Kilburn, London, to John Vine Milne, who was born in Jamaica, and Sarah Marie Milne (née Heginbotham), on 18 January 1882. He grew up at Henley House School, 6/7 Mortimer Road (now Crescent), Kilburn, a small independent school run by his father. He taught himself to read at the age of two. One of his teachers was H. G. Wells, who taught there in 1889--90. Milne attended Westminster School and Trinity College, Cambridge, where he studied on a mathematics scholarship, graduating with a Bachelor of Arts in Mathematics in 1903, though he was always interested in writing. He edited and wrote for *Granta*, a student magazine. He collaborated with his brother Kenneth and their articles appeared over the initials AKM. Milne\'s work came to the attention of the leading British humour magazine *Punch*, where Milne was to become a contributor and later an assistant editor. Considered a talented cricket fielder, Milne played for two amateur teams that were largely composed of British writers: the Allahakbarries and the Authors XI. His teammates included fellow writers J. M. Barrie, Arthur Conan Doyle and P. G. Wodehouse.
Milne joined the British Army during World War I and served as an officer in the Royal Warwickshire Regiment. He was commissioned into the 4th Battalion, Royal Warwickshire Regiment, on 1 February 1915 as a second lieutenant (on probation). His commission was confirmed on 20 December 1915. He served on the Somme as a signals officer from July--November 1916, but caught trench fever and was invalided back to England. Having recuperated, he worked as a signals instructor, before being recruited into military intelligence to write propaganda articles for MI7 (b) between 1917 and 1918. He was discharged on 14 February 1919, and settled in Mallord Street, Chelsea. He relinquished his commission on 19 February 1920, retaining the rank of lieutenant.
After the war, he wrote a denunciation of war titled *Peace with Honour* (1934), which he retracted somewhat with 1940\'s *War with Honour*. During World War II, Milne was one of the most prominent critics of fellow English writer (and Authors XI cricket teammate) P. G. Wodehouse, who was captured at his country home in France by the Nazis and imprisoned for a year. Wodehouse made radio broadcasts about his internment, which were broadcast from Berlin. Although the light-hearted broadcasts made fun of the Germans, Milne accused Wodehouse of committing an act of near treason by cooperating with his country\'s enemy. Wodehouse got some revenge on his former friend (e.g. in *The Mating Season*) by creating fatuous parodies of the Christopher Robin poems in some of his later stories, and claiming that Milne \"was probably jealous of all other writers\.... But I loved his stuff.\"
Milne married Dorothy \"Daphne\" de Sélincourt (1890--1971) in 1913 and their son Christopher Robin Milne was born in 1920. In 1925, Milne bought a country home, Cotchford Farm, in Hartfield, East Sussex.
During World War II, Milne was a captain in the British Home Guard in Hartfield & Forest Row, insisting on being plain \"Mr. Milne\" to the members of his platoon. He retired to the farm after a stroke and brain surgery in 1952 left him an invalid; and by August 1953, \"he seemed very old and disenchanted.\" Milne died in January 1956, aged 74.
## Literary career {#literary_career}
### 1903 to 1925 {#to_1925}
After graduating from Cambridge University in 1903, A. A. Milne contributed humorous verse and whimsical essays to *Punch*, joining the staff in 1906 and becoming an assistant editor.
During this period he published 18 plays and three novels, including the murder mystery *The Red House Mystery* (1922). His son was born in August 1920 and in 1924 Milne produced a collection of children\'s poems, *When We Were Very Young*, which were illustrated by *Punch* staff cartoonist E. H. Shepard. A collection of short stories for children *A Gallery of Children*, and other stories that became part of the Winnie-the-Pooh books, were first published in 1925.
Milne was an early screenwriter for the nascent British film industry, writing four stories filmed in 1920 for the company Minerva Films (founded in 1920 by the actor Leslie Howard and his friend and story editor Adrian Brunel). These were *The Bump*, starring Aubrey Smith; *Twice Two*; *Five Pound Reward*; and *Bookworms*. Some of these films survive in the archives of the British Film Institute. Milne had met Howard when the actor starred in Milne\'s play *Mr Pim Passes By* in London.
Looking back on this period (in 1926), Milne observed that when he told his agent that he was going to write a detective story, he was told that what the country wanted from a \"*Punch* humorist\" was a humorous story; when two years later he said he was writing nursery rhymes, his agent and publisher were convinced he should write another detective story; and after another two years, he was being told that writing a detective story would be in the worst of taste given the demand for children\'s books. He concluded that \"the only excuse which I have yet discovered for writing anything is that I want to write it; and I should be as proud to be delivered of a Telephone Directory *con amore* as I should be ashamed to create a Blank Verse Tragedy at the bidding of others.\"
### 1926 to 1928 {#to_1928}
Milne is most famous for his two *Pooh* books about a boy named Christopher Robin after his son, Christopher Robin Milne (1920--1996), and various characters inspired by his son\'s stuffed animals, most notably the bear named Winnie-the-Pooh. Christopher Robin Milne\'s stuffed bear, originally named Edward, was renamed Winnie after a Canadian black bear named Winnie (after Winnipeg), which was used as a military mascot in World War I, and left to London Zoo during the war. \"The Pooh\" comes from a swan the young Milne named \"Pooh\". E. H. Shepard illustrated the original Pooh books, using his own son\'s teddy Growler (\"a magnificent bear\") as the model. The rest of Christopher Robin Milne\'s toys, Piglet, Eeyore, Kanga, Roo and Tigger, were incorporated into A. A. Milne\'s stories, and two more characters -- Rabbit and Owl -- were created by Milne\'s imagination. Christopher Robin Milne\'s own toys are now on display in New York where 750,000 people visit them every year. The fictional Hundred Acre Wood of the Pooh stories derives from Five Hundred Acre Wood in Ashdown Forest in East Sussex, South East England, where the Pooh stories were set. Milne lived on the northern edge of the forest at Cotchford Farm, 51.090 0.107 display=inline, and took his son on walking trips there. E. H. Shepard drew on the landscapes of Ashdown Forest as inspiration for many of the illustrations he provided for the Pooh books. The adult Christopher Robin commented: \"Pooh\'s Forest and Ashdown Forest are identical.\" Popular tourist locations at Ashdown Forest include: *Galleon\'s Lap*, *The Enchanted Place*, the *Heffalump Trap* and *Lone Pine*, *Eeyore\'s Sad and Gloomy Place*, and the wooden *Pooh Bridge* where Pooh and Piglet invented Poohsticks.
Not yet known as Pooh, he made his first appearance in a poem, \"Teddy Bear\", published in *Punch* magazine in February 1924 and republished that year in *When We Were Very Young*. Pooh first appeared in the *London Evening News* on Christmas Eve, 1925, in a story called \"The Wrong Sort of Bees\". *Winnie-the-Pooh* was published in 1926, followed by *The House at Pooh Corner* in 1928. A second collection of nursery rhymes, *Now We Are Six*, was published in 1927. All four books were illustrated by E. H. Shepard. Milne also published four plays in this period. He also \"gallantly stepped forward\" to contribute a quarter of the costs of dramatising P. G. Wodehouse\'s *A Damsel in Distress*. *The World of Pooh* won the Lewis Carroll Shelf Award in 1958.
### 1929 onward
The success of his children\'s books was to become a source of considerable annoyance to Milne, whose self-avowed aim was to write whatever he pleased and who had, until then, found a ready audience for each change of direction: he had freed pre-war *Punch* from its ponderous facetiousness; he had made a considerable reputation as a playwright (like his idol J. M. Barrie) on both sides of the Atlantic; he had produced a witty piece of detective writing in *The Red House Mystery* (although this was severely criticised by Raymond Chandler for the implausibility of its plot in his essay *The Simple Art of Murder* in the eponymous collection that appeared in 1950). But once Milne had, in his own words, \"said goodbye to all that in 70,000 words\" (the approximate length of his four principal children\'s books), he had no intention of producing any reworkings lacking in originality, given that one of the sources of inspiration, his son, was growing older.
Another reason Milne stopped writing children\'s books, and especially about Winnie-the-Pooh, was that he felt \"amazement and disgust\" over the immense fame his son was exposed to, and said that \"I feel that the legal Christopher Robin has already had more publicity than I want for him. I do not want CR Milne to ever wish that his name were Charles Robert.\"
In his literary home, *Punch*, where the *When We Were Very Young* verses had first appeared, Methuen continued to publish whatever Milne wrote, including the long poem \"The Norman Church\" and an assembly of articles entitled *Year In, Year Out* (which Milne likened to a benefit night for the author).
In 1929, Milne adapted Kenneth Grahame\'s novel *The Wind in the Willows* for the stage as *Toad of Toad Hall*. The title was an implicit admission that such chapters as Chapter 7, \"The Piper at the Gates of Dawn,\" could not survive translation to the theatre. A special introduction written by Milne is included in some editions of Grahame\'s novel. It was first performed at the Playhouse Theatre, Liverpool, on 21 December 1929 before it made its West End debut the following year at the Lyric Theatre on 17 December 1930. The play was revived in the West End from 1931 to 1935, and since the 1960s there have been West End revivals during the Christmas season; actors who have performed in the play include Judi Dench and Ian McKellen.
Milne and his wife became estranged from their son, who came to resent what he saw as his father\'s exploitation of his childhood and came to hate the books that had thrust him into the public eye. Christopher\'s marriage to his first cousin, Lesley de Sélincourt, distanced him still further from his parents -- Lesley\'s father and Christopher\'s mother had not spoken to each other for 30 years.
## Death and legacy {#death_and_legacy}
### Commemoration
Milne died at his home in Hartfield, Sussex, on 31 January 1956, 13 days after his 74th birthday. A memorial service took place on 10 February at All Hallows-by-the-Tower church in London.
The rights to A. A. Milne\'s Pooh books were left to four beneficiaries: his family, the Royal Literary Fund, Westminster School and the Garrick Club. After Milne\'s death in 1956, his widow sold her rights to the Pooh characters to Stephen Slesinger, whose widow sold the rights after Slesinger\'s death to Walt Disney Productions, which has made many Pooh cartoon movies, a Disney Channel television show, as well as Pooh-related merchandise. In 2001, the other beneficiaries sold their interest in the estate to the Disney Corporation for \$350m. Previously Disney had been paying twice-yearly royalties to these beneficiaries. The estate of E. H. Shepard also received a sum in the deal. The UK copyright on the text of the original Winnie the Pooh books expires on 1 January 2027; at the beginning of the year after the 70th anniversary of the author\'s death (PMA-70), and has already expired in those countries with a PMA-50 rule. This applies to all of Milne\'s works except those first published posthumously. The illustrations in the Pooh books will remain under copyright until the same amount of time after the illustrator\'s death has passed; in the UK, this will be 1 January 2047.
In the US, copyright on the four children\'s books (including the illustrations) expired 95 years after publication of each of the books. Specifically: copyright on the book *When We Were Very Young* expired in 2020; copyright on the book *Winnie-the-Pooh* expired in 2022; copyright on the book *Now We Are Six* expired in 2023; and copyright on the book *The House at Pooh Corner* expired in 2024.
In 2008, a collection of original illustrations featuring Winnie-the-Pooh and his animal friends sold for more than £1.2 million at auction at Sotheby\'s, London. *Forbes* magazine ranked Winnie the Pooh the most valuable fictional character in 2002; Winnie the Pooh merchandising products alone had annual sales of more than \$5.9 billion. In 2005, Winnie the Pooh generated \$6 billion, a figure surpassed only by Mickey Mouse.
A memorial plaque in Ashdown Forest, unveiled by Christopher Robin in 1979, commemorates the work of A. A. Milne and Shepard in creating the world of Pooh. The inscription states they \"captured the magic of Ashdown Forest, and gave it to the world\". Milne once wrote of Ashdown Forest: \"In that enchanted place on the top of the forest a little boy and his bear will always be playing.\"
In 2003, *Winnie-the-Pooh* was ranked number 7 on the BBC\'s The Big Read poll which determined the UK\'s \"best-loved novels\". In 2006, Winnie-the-Pooh received a star on the Hollywood Walk of Fame, marking the 80th birthday of Milne\'s creation.
Marking the 90th anniversary of Milne\'s creation of the character, and the 90th birthday of Queen Elizabeth II, *Winnie-the-Pooh Meets the Queen* (2016) sees Pooh meet the Queen at Buckingham Palace. The illustrated and audio adventure is narrated by the actor Jim Broadbent. Also in 2016, a new character, a Penguin, was unveiled in *The Best Bear in All the World*, which was inspired by a long-lost photograph of Milne and his son Christopher with a toy penguin.
An exhibition entitled *Winnie-the-Pooh: Exploring a Classic* appeared at the Victoria and Albert Museum in London from 9 December 2017 to 8 April 2018.
The composer Harold Fraser-Simson, a near neighbour, produced six books of Milne songs between 1924 and 1932. The poems have been parodied many times, including in the books *When We Were Rather Older* and *Now We Are Sixty*. The 1963 film *The King\'s Breakfast* was based on Milne\'s poem of the same name.
Milne has been portrayed in television and film. Domhnall Gleeson plays him in *Goodbye Christopher Robin*, a 2017 biographical drama film. In the 2018 fantasy film *Christopher Robin*, an extension of the Disney Winnie the Pooh franchise, Tristan Sturrock plays Milne, and filming took place at Ashdown Forest.
An elementary school in Houston, Texas, operated by the Houston Independent School District (HISD), is named after Milne. The school, A. A. Milne Elementary School in Brays Oaks, opened in 1991.
## Archive
thumb\|right\|Milne bequeathed his Winnie-the-Pooh manuscripts to the Wren Library *(pictured)* at Trinity College, Cambridge
The original manuscripts for *Winnie-the-Pooh* and *The House at Pooh Corner* are archived at Trinity College Library, Cambridge.
The bulk of A. A. Milne\'s papers are housed at the Harry Ransom Center at the University of Texas at Austin. The collection, established at the centre in 1964, consists of manuscript drafts and fragments for over 150 of Milne\'s works, as well as correspondence, legal documents, genealogical records, and some personal effects. The library division holds several books formerly belonging to Milne and his wife Dorothy. The center also has small collections of correspondence from Christopher Robin Milne and Milne\'s frequent illustrator E. H. Shepard.
## Religious views {#religious_views}
Milne did not speak out much on the subject of religion, although he used religious terms to explain his decision, while remaining a pacifist, to join the British Home Guard. He wrote: \"In fighting Hitler we are truly fighting the Devil, the Anti-Christ \... Hitler was a crusader against God.\"
His best known comment on the subject was recalled on his death: `{{blockquote|The Old Testament is responsible for more atheism, agnosticism, disbelief – call it what you will{{snd}}than any book ever written; it has emptied more churches than all the counter-attractions of cinema, motor bicycle and golf course.<ref>{{cite book|last=Simpson |first=James B. |title=Simpson's Contemporary Quotations |url=http://www.bartleby.com/63/93/4393.html |year=1988 |publisher=[[Houghton Mifflin]] |location=Boston, Massachusetts |isbn=0-395-43085-2 |url-status=dead |archive-url=https://web.archive.org/web/20090122122546/http://www.bartleby.com/63/93/4393.html |archive-date=22 January 2009 }}</ref>}}`{=mediawiki}
He wrote in the poem \"Explained\":
He also wrote in the poem \"Vespers\":
## Works
### Novels
- *Lovers in London* (1905. Some consider this more of a short story collection; Milne did not like it and considered *The Day\'s Play* as his first book.)
- *Once on a Time* (1917)
- *Mr. Pim* (1921) (A novelisation of his 1919 play *Mr. Pim Passes By*)
- *The Red House Mystery* (1922). Serialised: London (Daily News), serialised daily from 3 to 28 August 1921
- *Two People* (1931) (Inside jacket claims this is Milne\'s first attempt at a novel.)
- *Four Days\' Wonder* (1933)
- *Chloe Marr* (1946)
### Non-fiction {#non_fiction}
- *Peace With Honour* (1934)
- *It\'s Too Late Now: The Autobiography of a Writer* (1939)
- *War With Honour* (1940)
- *War Aims Unlimited* (1941)
- *Year In, Year Out* (1952) (illustrated by E. H. Shepard)
#### *Punch* articles {#punch_articles}
- *The Day\'s Play* (1910)
- *The Holiday Round* (1912)
- *Once a Week* (1914)
- *The Sunny Side* (1921)
- *Those Were the Days* (1929) \[The four volumes above, compiled\]
### Newspaper articles and book introductions {#newspaper_articles_and_book_introductions}
- *The Chronicles of Clovis* by \"Saki\" (1911) \[Introduction to\]
- *Not That It Matters* (1919)
- *If I May* (1920)
- *By Way of Introduction* (1929)
- *Women and Children First!*. John Bull, 10 November 1934
- *It Depends on the Book* (1943, in September issue of Red Cross Newspaper *The Prisoner of War*)
### Story collections for children {#story_collections_for_children}
- *A Gallery of Children* (1925)
- *Winnie-the-Pooh* (1926) (illustrated by Ernest H. Shepard)
- *The House at Pooh Corner* (1928) (illustrated by E. H. Shepard)
- *Short Stories*
### Poetry collections for children {#poetry_collections_for_children}
- *When We Were Very Young* (1924) (illustrated by E. H. Shepard)
- *Now We Are Six* (1927) (illustrated by E. H. Shepard)
### Story collections {#story_collections}
- *The Secret and other stories* (1929)
- *The Birthday Party* (1948)
- *A Table Near the Band* (1950)
### Poetry
- *When We Were Very Young* (1924) (illustrated by E. H. Shepard)
- *For the Luncheon Interval* (1925) \[poems from *Punch*\]
- *Now We Are Six* (1927) (illustrated by E. H. Shepard)
- *Behind the Lines* (1940)
- *The Norman Church* (1948)
### Screenplays and plays {#screenplays_and_plays}
- *Wurzel-Flummery* (1917)
- *Belinda* (1918)
- *The Boy Comes Home* (1918)
- *Make-Believe* (1918) (children\'s play)
- *The Camberley Triangle* (1919)
- *Mr. Pim Passes By* (1919)
- *The Red Feathers* (1920)
- *The Romantic Age* (1920)
- *The Stepmother* (1920)
- *The Truth About Blayds* (1920)
- *The Bump* (1920, Minerva Films), starring C. Aubrey Smith and Faith Celli
- *Twice Two* (1920, Minerva Films)
- *Five Pound Reward* (1920, Minerva Films)
- *Bookworms* (1920, Minerva Films)
- *The Great Broxopp* (1921)
- *The Dover Road* (1921)
- *The Lucky One* (1922)
- *The Truth About Blayds* (1922)
- *The Artist: A Duologue* (1923)
- *Give Me Yesterday* (1923) (a.k.a. *Success* in the UK)
- *Ariadne* (1924)
- *The Man in the Bowler Hat: A Terribly Exciting Affair* (1924)
- *To Have the Honour* (1924)
- *Portrait of a Gentleman in Slippers* (1926)
- *Success* (1926)
- *Miss Marlow at Play* (1927)
- *Winnie the Pooh*. Written specially by Milne for a \'Winnie the Pooh Party\' in aid of the National Mother-Saving Campaign, and performed once at Seaford House on 17 March 1928
- *The Fourth Wall* or *The Perfect Alibi* (1928) (later adapted for the film *Birds of Prey* (1930), directed by Basil Dean)
- *The Ivory Door* (1929)
- *Toad of Toad Hall* (1929) (adaptation of *The Wind in the Willows*)
- *Michael and Mary* (1930)
- *Other People\'s Lives* (1933) (a.k.a. *They Don\'t Mean Any Harm*)
- *Miss Elizabeth Bennet* (1936) \[based on *Pride and Prejudice*\]
- *Sarah Simple* (1937)
- *Gentleman Unknown* (1938)
- *The General Takes Off His Helmet* (1939) in *The Queen\'s Book of the Red Cross*
- *The Ugly Duckling* (1941)
- *Before the Flood* (1951).
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Asociación Alumni
|
**Asociación Alumni**, usually just **Alumni**, is an Argentine rugby union club located in Tortuguitas, Greater Buenos Aires. The senior squad currently competes at Top 12, the first division of the Unión de Rugby de Buenos Aires league system.
The club has ties with former football club Alumni because both were established by Buenos Aires English High School students.
## History
### Background
The first club with the name \"Alumni\" played association football, having been found in 1898 by students of Buenos Aires English High School (BAEHS) along with director Alexander Watson Hutton. Originally under the name \"English High School A.C.\", the team would be later obliged by the Association to change its name, therefore \"Alumni\" was chosen, following a proposal by Carlos Bowers, a former student of the school.
Alumni was the most successful team during the first years of Argentine football, winning 10 of 14 league championships contested. Alumni is still considered the first great football team in the country. Alumni was reorganised in 1908, \"in order to encourage people to practise all kinds of sports, specially football\". This was the last try to develop itself as a sports club rather than just as a football team, as Lomas, Belgrano and Quilmes had successfully done in the past, but the efforts were not enough. Alumni played its last game in 1911 and was definitely dissolved on April 24, 1913.
### Rebirth through rugby {#rebirth_through_rugby}
In 1951, two guards of the BAEHS, Daniel Ginhson (also a former player of Buenos Aires F.C.) and Guillermo Cubelli, supported by the school\'s alumni and fathers of the students, decided to establish a club focused on rugby union exclusively. Former players of Alumni football club and descendants of other players already dead gave their permission to use the name \"Alumni\".
On December 13, in a meeting presided by Carlos Bowers himself (who had proposed the name \"Alumni\" to the original football team 50 years before), the club was officially established under the name \"Asociación Juvenil Alumni\", also adopting the same colors as its predecessor.
The team achieved good results and in 1960 the club presented a team that won the third division of the Buenos Aires league, reaching the second division. Since then, Alumni has played at the highest level of Argentine rugby and its rivalry with Belgrano Athletic Club is one of the fiercest local derbies in Buenos Aires. Alumni would later climb up to the first division winning 5 titles: 4 consecutive between 1989 and 1992, and the other in 2001.
In 2002, Alumni won its first Nacional de Clubes title, defeating Jockey Club de Rosario 23--21 in the final.
## Players
### Current roster {#current_roster}
As of January 2018: `{{div col|colwidth=22em}}`{=mediawiki}
- Federico Lucca
- Gaspar Baldunciel
- Guido Cambareri
- Iñaki Etchegaray
- Bernardo Quaranta
- Tobias Moyano
- Mariano Romanini
- Santiago Montagner
- Tomas Passerotti
- Lucas Frana
- Luca Sabato
- Franco Batezzatti
- Franco Sabato
- Rafael Desanto
- Nito Provenzano
- Tomas Bivort
- Juan.P Ceraso
- Santiago Alduncin
- Juan.P Anderson
- Lucas Magnasco
- Joaquin Diaz Luzzi
- Felipe Martignone
- Tomas Corneille
## Honours
- **Nacional de Clubes (1)**: 2002
- **Torneo de la URBA (7)**: 1989, 1990, 1991, 1992, 2001, 2018, 2024
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929 |
Alpha
|
**Alpha** `{{IPAc-en|'|æ|l|f|ə|audio=LL-Q1860 (eng)-Flame, not lame-Alpha.wav}}`{=mediawiki} `{{respell|ALF|ə}}`{=mediawiki} (uppercase `{{Script|Grek|'''Α'''}}`{=mediawiki}, lowercase `{{Script|Grek|'''α'''}}`{=mediawiki}) is the first letter of the Greek alphabet. In the system of Greek numerals, it has a value of one. Alpha is derived from the Phoenician letter *aleph* `{{angbr|𐤀}}`{=mediawiki}, whose name comes from the West Semitic word for \'ox\'. Letters that arose from alpha include the Latin letter `{{angbr|[[A]]}}`{=mediawiki} and the Cyrillic letter `{{angbr|[[A (Cyrillic)|А]]}}`{=mediawiki}.
## Uses
### Greek
In Ancient Greek, alpha was pronounced `{{IPAblink|ä|a}}`{=mediawiki} and could be either phonemically long (\[aː\]) or short (\[a\]). Where there is ambiguity, long and short alpha are sometimes written with a macron and breve today: *italic=no*.
- = *italic=no* **hōrā** `{{IPA|el|hɔ́ːraː}}`{=mediawiki} \"a time\"
- = *italic=no* **glôssa** `{{IPA|el|ɡlɔ̂ːssa}}`{=mediawiki} \"tongue\"
In Modern Greek, vowel length has been lost, and all instances of alpha simply represent the open front unrounded vowel `{{IPA|el|a|IPA}}`{=mediawiki}.
In the polytonic orthography of Greek, alpha, like other vowel letters, can occur with several diacritic marks: any of three accent symbols (*ά, ὰ, ᾶ*), and either of two breathing marks (*ἁ, ἀ*), as well as combinations of these. It can also combine with the iota subscript (*ᾳ*).
#### Greek grammar {#greek_grammar}
In the Attic--Ionic dialect of Ancient Greek, long alpha `{{IPA|[aː]}}`{=mediawiki} fronted to `{{IPAblink|ɛː}}`{=mediawiki} (eta). In Ionic, the shift took place in all positions. In Attic, the shift did not take place after epsilon, iota, and rho (*italic=no*; *e, i, r*). In Doric and Aeolic, long alpha is preserved in all positions.
- Doric, Aeolic, Attic *χώρᾱ* **chṓrā** -- Ionic *χώρη* **chṓrē**, \"country\"
- Doric, Aeolic *φᾱ́μᾱ* **phā́mā** -- Attic, Ionic *φήμη* **phḗmē**, \"report\"
Privative a is the Ancient Greek prefix *italic=no* or *italic=no* *a-, an-*, added to words to negate them. It originates from the Proto-Indo-European *\*n̥-* (syllabic nasal) and is cognate with English *un-*.
Copulative a is the Greek prefix *italic=no* or *italic=no* *ha-, a-*. It comes from Proto-Indo-European *\*sm̥*.
### Mathematics and science {#mathematics_and_science}
The letter alpha represents various concepts in physics and chemistry, including alpha radiation, angular acceleration, alpha particles, alpha carbon and strength of electromagnetic interaction (as fine-structure constant). Alpha also stands for thermal expansion coefficient of a compound in physical chemistry. In ethology, it is used to name the dominant individual in a group of animals. In aerodynamics, the letter is used as a symbol for the angle of attack of an aircraft and the word \"alpha\" is used as a synonym for this property.
In astronomy, α is often used to designate the brightest star in a constellation.
In mathematics, the letter alpha is used to denote the area underneath a normal curve in statistics to denote significance level when proving null and alternative hypotheses. It is also commonly used in algebraic solutions representing quantities such as angles. In mathematical logic, α is sometimes used as a placeholder for ordinal numbers. It is used for Stoneham numbers.
Most occurrences of alpha in science are the lowercase alpha. The uppercase letter alpha is not generally used as a symbol because it tends to be rendered identically to the uppercase Latin A.
The proportionality operator \"∝\" (in Unicode: U+221D) is sometimes mistaken for alpha.
### International Phonetic Alphabet {#international_phonetic_alphabet}
In the International Phonetic Alphabet, the letter ɑ, which looks similar to the lower-case alpha, represents the open back unrounded vowel.
## History and symbolism {#history_and_symbolism}
### Origin
The Phoenician alphabet was adopted for Greek in the early 8th century BC, perhaps in Euboea. The majority of the letters of the Phoenician alphabet were adopted into Greek with much the same sounds as they had had in Phoenician, but *ʼāleph*, the Phoenician letter representing the glottal stop `{{IPA|[ʔ]}}`{=mediawiki}, was adopted as representing the vowel `{{IPA|[a]}}`{=mediawiki}; similarly, *hē* `{{IPA|[h]}}`{=mediawiki} and *ʽayin* `{{IPA|[ʕ]}}`{=mediawiki} are Phoenician consonants that became Greek vowels, epsilon `{{IPA|[e]}}`{=mediawiki} and omicron `{{IPA|[o]}}`{=mediawiki}, respectively.
### Plutarch
Plutarch, in *Moralia*, presents a discussion on why the letter alpha stands first in the alphabet. Ammonius asks Plutarch what he, being a Boeotian, has to say for Cadmus, the Phoenician who reputedly settled in Thebes and introduced the alphabet to Greece, placing *alpha* first because it is the Phoenician name for ox---which, unlike Hesiod, the Phoenicians considered not the second or third, but the first of all necessities. \"Nothing at all,\" Plutarch replied. He then added that he would rather be assisted by Lamprias, his own grandfather, than by Dionysus\' grandfather, i.e. Cadmus. For Lamprias had said that the first articulate sound made is \"alpha\", because it is very plain and simple---the air coming off the mouth does not require any motion of the tongue---and therefore this is the first sound that children make.
According to Plutarch\'s natural order of attribution of the vowels to the planets, alpha was connected with the Moon.
### Alpha and Omega {#alpha_and_omega}
*Main article: Alpha and Omega*
As the first letter of the alphabet, Alpha as a Greek numeral came to represent the number 1. Therefore, Alpha, both as a symbol and term, is used to refer to the \"first\", or \"primary\", or \"principal\" (most significant) occurrence or status of a thing.
The New Testament has God declaring himself to be the \"Alpha and Omega, the beginning and the end, the first and the last.\" (Revelation 22:13, KJV, and see also 1:8).
Consequently, the term \"alpha\" has also come to be used to denote \"primary\" position in social hierarchy, examples being the concept of dominant \"alpha\" members in groups of animals.
## Unicode
All code points with `{{sc|ALPHA}}`{=mediawiki} or `{{sc|ALFA}}`{=mediawiki} but without `{{sc|WITH}}`{=mediawiki} (for accented Greek characters, see Greek diacritics: Computer encoding):
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Alvin Toffler
|
\| signature = }} **Alvin Eugene Toffler** (October 4, 1928 -- June 27, 2016) was an American writer, futurist, and businessman known for his works discussing modern technologies, including the digital revolution and the communication revolution, with emphasis on their effects on cultures worldwide. He is regarded as one of the world\'s outstanding futurists.
Toffler was an associate editor of *Fortune* magazine. In his early works he focused on technology and its impact, which he termed \"information overload\". In 1970, his first major book about the future, *Future Shock*, became a worldwide best-seller and has sold over 6 million copies.
He and his wife Heidi Toffler (1929--2019), who collaborated with him for most of his writings, moved on to examining the reaction to changes in society with another best-selling book, *The Third Wave*, in 1980. In it, he foresaw such technological advances as cloning, personal computers, the Internet, cable television and mobile communication. His later focus, via their other best-seller, *Powershift*, (1990), was on the increasing power of 21st-century military hardware and the proliferation of new technologies.
He founded Toffler Associates, a management consulting company, and was a visiting scholar at the Russell Sage Foundation, visiting professor at Cornell University, faculty member of the New School for Social Research, a White House correspondent, and a business consultant. Toffler\'s ideas and writings were a significant influence on the thinking of business and government leaders worldwide, including China\'s Zhao Ziyang, and AOL founder Steve Case.
## Early life {#early_life}
Alvin Toffler was born on October 4, 1928, in New York City, and raised in Brooklyn. He was the son of Rose (Albaum) and Sam Toffler, a furrier, both Polish Jews who had migrated to America. He had one younger sister. He was inspired to become a writer at the age of 7 by his aunt and uncle, who lived with the Tofflers. \"They were Depression-era literary intellectuals,\" Toffler said, \"and they always talked about exciting ideas.\"
Toffler graduated from New York University in 1950 as an English major, though by his own account he was more focused on political activism than grades. He met his future wife, Adelaide Elizabeth Farrell (nicknamed \"Heidi\"), when she was starting a graduate course in linguistics. Being radical students, they decided against further graduate work and moved to Cleveland, Ohio, where they married on April 29, 1950.
## Career
Seeking experiences to write about, Alvin and Heidi Toffler spent the next five years as blue collar workers on assembly lines while studying industrial mass production in their daily work. He compared his own desire for experience to other writers, such as Jack London, who in his quest for subjects to write about sailed the seas, and John Steinbeck, who went to pick grapes with migrant workers. In their first factory jobs, Heidi became a union shop steward in the aluminum foundry where she worked. Alvin became a millwright and welder. In the evenings Alvin would write poetry and fiction, but discovered he was proficient at neither.
His hands-on practical labor experience helped Alvin Toffler land a position at a union-backed newspaper, a transfer to its Washington bureau in 1957, then three years as a White House correspondent, covering Congress and the White House for a Pennsylvania daily newspaper.
They returned to New York City in 1959 when *Fortune* magazine invited Alvin to become its labor columnist, later having him write about business and management. After leaving *Fortune* magazine in 1962, Toffler began a freelance career, writing long form articles for scholarly journals and magazines. His 1964 *Playboy interviews* with Russian novelist Vladimir Nabokov and Ayn Rand were considered among the magazine\'s best. His interview with Rand was the first time the magazine had given such a platform to a female intellectual, which as one commentator said, \"the real bird of paradise Toffler captured for Playboy in 1964 was Ayn Rand.\"
Toffler was hired by IBM to conduct research and write a paper on the social and organizational impact of computers, leading to his contact with the earliest computer \"gurus\" and artificial intelligence researchers and proponents. Xerox invited him to write about its research laboratory and AT&T consulted him for strategic advice. This AT&T work led to a study of telecommunications, which advised the company\'s top management to break up the company more than a decade before the government forced AT&T to break up.
In the mid-1960s, the Tofflers began five years of research on what would become *Future Shock*, published in 1970. It has sold over 6 million copies worldwide, according to the *New York Times,* or over 15 million copies according to the Tofflers\' Web site. Toffler coined the term \"future shock\" to refer to what happens to a society when change happens too fast, which results in social confusion and normal decision-making processes breaking down. The book has never been out of print and has been translated into dozens of languages.
He continued the theme in *The Third Wave* in 1980. While he describes the first and second waves as the agricultural and industrial revolutions, the \"third wave,\" a phrase he coined, represents the current information, computer-based revolution. He forecast the spread of the Internet and email, interactive media, cable television, cloning, and other digital advancements. He claimed that one of the side effects of the digital age has been \"information overload,\" another term he coined. In 1990, he wrote *Powershift*, also with the help of his wife, Heidi.
In 1996, with American business consultant Tom Johnson, they co-founded Toffler Associates, an advisory firm designed to implement many of the ideas the Tofflers had written on. The firm worked with businesses, NGOs, and governments in the United States, South Korea, Mexico, Brazil, Singapore, Australia, and other countries. During this period in his career, Toffler lectured worldwide, taught at several schools and met world leaders, such as Mikhail Gorbachev, along with key executives and military officials.
### Ideas and opinions {#ideas_and_opinions}
Toffler stated many of his ideas during an interview with the Australian Broadcasting Corporation in 1998. \"Society needs people who take care of the elderly and who know how to be compassionate and honest,\" he said. \"Society needs people who work in hospitals. Society needs all kinds of skills that are not just cognitive; they\'re emotional, they\'re affectional. You can\'t run the society on data and computers alone.\"
His opinions about the future of education, many of which were in *Future Shock*, have often been quoted. An often misattributed quote, however, is that of psychologist Herbert Gerjuoy: \"Tomorrow\'s illiterate will not be the man who can\'t read; he will be the man who has not learned how to learn.\"
Early in his career, after traveling to other countries, he became aware of the new and myriad inputs that visitors received from these other cultures. He explained during an interview that some visitors would become \"truly disoriented and upset\" by the strange environment, which he described as a reaction to culture shock. From that issue, he foresaw another problem for the future, when a culturally \"new environment comes to you \... and comes to you rapidly.\" That kind of sudden cultural change within one\'s own country, which he felt many would not understand, would lead to a similar reaction, one of \"future shock\", which he wrote about in his book by that title. Toffler writes: `{{blockquote|We must search out totally new ways to anchor ourselves, for all the old roots—religion, nation, community, family, or profession—are now shaking under the hurricane impact of the accelerative thrust.<ref name=CBC/><ref name=AP>{{cite news|url=https://www.cbc.ca/news/arts/alvin-toffler-author-obit-1.3659263|title=Alvin Toffler, Future Shock and Third Wave author, dead at 87|date=June 29, 2016|publisher=[[CBC News]]|agency=[[Associated Press]]|url-status=live|archive-url=https://web.archive.org/web/20160813081640/https://www.cbc.ca/news/arts/alvin-toffler-author-obit-1.3659263|archive-date=August 13, 2016}}</ref>}}`{=mediawiki}
In *The Third Wave*, Toffler describes three types of societies, based on the concept of \"waves\"---each wave pushes the older societies and cultures aside. He describes the \"First Wave\" as the society after agrarian revolution and replaced the first hunter-gatherer cultures. The \"Second Wave,\" he labels society during the Industrial Revolution (ca. late 17th century through the mid-20th century). That period saw the increase of urban industrial populations which had undermined the traditional nuclear family, and initiated a factory-like education system, and the growth of the corporation. Toffler said:
The \"Third Wave\" was a term he coined to describe the post-industrial society, which began in the late 1950s. His description of this period dovetails with other futurist writers, who also wrote about the Information Age, Space Age, Electronic Era, Global Village, terms which highlighted a scientific-technological revolution. The Tofflers claimed to have predicted a number of geopolitical events, such as the collapse of the Soviet Union, the fall of the Berlin Wall and the future economic growth in the Asia-Pacific region.
## Influences and popular culture {#influences_and_popular_culture}
Toffler often visited with dignitaries in Asia, including China\'s Zhao Ziyang, Singapore\'s Lee Kuan Yew and South Korea\'s Kim Dae Jung, all of whom were influenced by his views as Asia\'s emerging markets increased in global significance during the 1980s and 1990s. Although they had originally censored some of his books and ideas, China\'s government cited him along with Franklin Roosevelt and Bill Gates as being among the Westerners who had most influenced their country. *The Third Wave* along with a video documentary based on it became best-sellers in China and were widely distributed to schools. The video\'s success inspired the marketing of videos on related themes in the late 1990s by Infowars, whose name is derived from the term coined by Toffler in the book. Toffler\'s influence on Asian thinkers was summed up in an article in *Daedalus*, published by the American Academy of Arts & Sciences: `{{blockquote|Where an earlier generation of Chinese, Korean, and Vietnamese revolutionaries wanted to re-enact the [[Paris Commune]] as imagined by [[Karl Marx]], their post-revolutionary successors now want to re-enact [[Silicon Valley]] as imagined by Alvin Toffler.<ref name=Denver/>}}`{=mediawiki}
U.S. House Speaker Newt Gingrich publicly lauded his ideas about the future, and urged members of Congress to read Toffler\'s book, *Creating a New Civilization* (1995). Others, such as AOL founder Steve Case, cited Toffler\'s *The Third Wave* as a formative influence on his thinking, which inspired him to write *The Third Wave: An Entrepreneur\'s Vision of the Future* in 2016. Case said that Toffler was a \"real pioneer in helping people, companies and even countries lean into the future.\"
In 1980, Ted Turner founded CNN, which he said was inspired by Toffler\'s forecasting the end of the dominance of the three main television networks. Turner\'s company, Turner Broadcasting, published Toffler\'s *Creating a New Civilization* in 1995. Shortly after the book was released, the former Soviet president Mikhail Gorbachev hosted the Global Governance Conference in San Francisco with the theme, *Toward a New Civilization*, which was attended by dozens of world figures, including the Tofflers, George H. W. Bush, Margaret Thatcher, Carl Sagan, Abba Eban and Turner with his then-wife, actress Jane Fonda.
Mexican billionaire Carlos Slim was influenced by his works, and became a friend of the writer. Global marketer J.D. Power also said he was inspired by Toffler\'s works.
Since the 1960s, people had tried to make sense out of the effect of new technologies and social change, a problem which made Toffler\'s writings widely influential beyond the confines of scientific, economic, and public policy. His works and ideas have been subject to various criticisms, usually with the same argumentation used against futurology: that foreseeing the future is nigh impossible.
Techno music pioneer Juan Atkins cites Toffler\'s phrase \"techno rebels\" in *The Third Wave* as inspiring him to use the word \"techno\" to describe the musical style he helped to create Musician Curtis Mayfield released a disco song called \"Future Shock,\" later covered in an electro version by Herbie Hancock. Science fiction author John Brunner wrote \"The Shockwave Rider,\" from the concept of \"future shock.\"
The nightclub Toffler, in Rotterdam, is named after him.
In the song \"Victoria\" by The Exponents, the protagonist\'s daily routine and cultural interests are described: \"She\'s up in time to watch the soap operas, reads Cosmopolitan and Alvin Toffler\".
## Critical assessment {#critical_assessment}
Accenture, the management consultancy firm, identified Toffler in 2002 as being among the most influential voices in business leaders, along with Bill Gates and Peter Drucker. Toffler has also been described in a *Financial Times* interview as the \"world\'s most famous futurologist\". In 2006, the *People\'s Daily* classed him among the 50 foreigners who shaped modern China, which one U.S. newspaper notes made him a \"guru of sorts to world statesmen.\" Chinese Premier and General Secretary Zhao Ziyang was greatly influenced by Toffler. He convened conferences to discuss *The Third Wave* in the early 1980s, and in 1985 the book was the No. 2 best seller in China.
Author Mark Satin characterizes Toffler as an important early influence on radical centrist political thought.
Newt Gingrich became close to the Tofflers in the 1970s and said *The Third Wave* had immensely influenced his own thinking and was \"one of the great seminal works of our time.\"
## Selected awards {#selected_awards}
Toffler has received several prestigious prizes and awards, including the McKinsey Foundation Book Award for Contributions to Management Literature, Officier de L\'Ordre des Arts et Lettres, and appointments, including Fellow of the American Association for the Advancement of Science and the International Institute for Strategic Studies.
In 2006, Alvin and Heidi Toffler were recipients of Brown University\'s Independent Award.
## Personal life {#personal_life}
Toffler was married to Heidi Toffler (born Adelaide Elizabeth Farrell), also a writer and futurist. They lived in the Bel Air section of Los Angeles, California, and previously lived in Redding, Connecticut.
The couple\'s only child, Karen Toffler (1954--2000), died at age 46 after more than a decade suffering from Guillain--Barré syndrome.
Alvin Toffler died in his sleep on June 27, 2016, at his home in Los Angeles. No cause of death was given. He is buried at Westwood Memorial Park.
| 2025-08-01T00:00:00 |
953 |
Azincourt
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**Azincourt** (`{{IPAc-en|ˈ|æ|z|ɪ|n|k|ɔːr|(|t|)|audio=LL-Q1860 (eng)-Naomi Persephone Amethyst (NaomiAmethyst)-Azincourt.wav}}`{=mediawiki} `{{respell|AZ|in|kor(t)}}`{=mediawiki} ; `{{IPA|fr|azɛ̃kuʁ}}`{=mediawiki}) is a commune in the Pas-de-Calais department in northern France. It is situated 12 mi north-west of Saint-Pol-sur-Ternoise on the D71 road between Hesdin and Fruges.
The Late Medieval Battle of Agincourt between the English and the French took place in the commune in 1415.
## Toponym
The name is attested as *Aisincurt* in 1175, derived from a Germanic masculine name Aizo, Aizino and the early Northern French word *curt* (which meant a farm with a courtyard; derived from the Late Latin *cortem*). It is often known as **Agincourt** in English. There is a village that is named \"Agincourt\", located in the Meurthe-et-Moselle department in Eastern France. The name has no etymological link with Azincourt, and is derived separately from another male name *\*Ingin-*.
## History
Azincourt is known for being near the site of the battle fought on 25 October 1415 in which the army led by King Henry V of England defeated the forces led by Charles d\'Albret on behalf of Charles VI of France, which has gone down in history as the Battle of Agincourt. According to M. Forrest, the French knights were so encumbered by their armour that they were exhausted even before the start of the battle.
After he became king in 1509, Henry VIII is purported to have commissioned an English translation of a Life of Henry V so that he could emulate him, on the grounds that he thought that launching a campaign against France would help him to impose himself on the European stage. In 1513, Henry VIII crossed the English Channel, stopping by at Azincourt.
The battle, as was the tradition, was named after a nearby castle called Azincourt. The castle has since disappeared and the settlement now known as Azincourt adopted the name in the seventeenth century.
John Cassell wrote in 1857 that \"the village of Azincourt itself is now a group of dirty farmhouses and wretched cottages, but where the hottest of the battle raged, between that village and the commune of Tramecourt, there still remains a wood precisely corresponding with the one in which Henry placed his ambush; and there are yet existing the foundations of the castle of Azincourt, from which the king named the field.\"
## Population
## Sights
The original battlefield museum in the village featured model knights made out of Action Man figures. This has now been replaced by the Centre historique médiéval d\'Azincourt (CHM)---a more professional museum, conference centre and exhibition space incorporating laser, video, slide shows, audio commentaries, and some interactive elements. The museum building is shaped like a longbow similar to those used at the battle by archers under King Henry.
Since 2004 a large medieval festival organised by the local community, the CHM, The Azincourt Alliance, and various other UK societies commemorating the battle, local history and medieval life, arts and crafts has been held in the village. Prior to this date the festival was held in October, but due to the inclement weather and local heavy clay soil (like the battle) making the festival difficult, it was moved to the last Sunday in July.
## International relations {#international_relations}
Azincourt is twinned with Middleham, United Kingdom.
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Axon
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An **axon** (from Greek ἄξων *áxōn*, axis) or **nerve fiber** (or **nerve** **fibre**: see spelling differences) is a long, slender projection of a nerve cell, or neuron, in vertebrates, that typically conducts electrical impulses known as action potentials away from the nerve cell body. The function of the axon is to transmit information to different neurons, muscles, and glands. In certain sensory neurons (pseudounipolar neurons), such as those for touch and warmth, the axons are called afferent nerve fibers and the electrical impulse travels along these from the periphery to the cell body and from the cell body to the spinal cord along another branch of the same axon. Axon dysfunction can be the cause of many inherited and acquired neurological disorders that affect both the peripheral and central neurons. Nerve fibers are classed into three types`{{Snd}}`{=mediawiki}group A nerve fibers, group B nerve fibers, and group C nerve fibers. Groups A and B are myelinated, and group C are unmyelinated. These groups include both sensory fibers and motor fibers. Another classification groups only the sensory fibers as Type I, Type II, Type III, and Type IV.
An axon is one of two types of cytoplasmic protrusions from the cell body of a neuron; the other type is a dendrite. Axons are distinguished from dendrites by several features, including shape (dendrites often taper while axons usually maintain a constant radius), length (dendrites are restricted to a small region around the cell body while axons can be much longer), and function (dendrites receive signals whereas axons transmit them). Some types of neurons have no axon and transmit signals from their dendrites. In some species, axons can emanate from dendrites known as axon-carrying dendrites. No neuron ever has more than one axon; however in invertebrates such as insects or leeches the axon sometimes consists of several regions that function more or less independently of each other.
Axons are covered by a membrane known as an axolemma; the cytoplasm within an axon is called axoplasm. Most axons branch, in some cases very profusely. The end branches of an axon are called telodendria. The swollen end of a telodendron is known as the axon terminal or end-foot which joins the dendrite or cell body of another neuron forming a synaptic connection. Axons usually make contact with other neurons at junctions called synapses but can also make contact with muscle or gland cells. In some circumstances, the axon of one neuron may form a synapse with the dendrites of the same neuron, resulting in an autapse. At a synapse, the membrane of the axon closely adjoins the membrane of the target cell, and special molecular structures serve to transmit electrical or electrochemical signals across the gap. Some synaptic junctions appear along the length of an axon as it extends; these are called *en passant boutons* (\"in passing boutons\") and can be in the hundreds or even the thousands along one axon. Other synapses appear as terminals at the ends of axonal branches.
A single axon, with all its branches taken together, can target multiple parts of the brain and generate thousands of synaptic terminals. A bundle of axons make a nerve tract in the central nervous system, and a fascicle in the peripheral nervous system. In placental mammals the largest white matter tract in the brain is the corpus callosum, formed of some 200 million axons in the human brain.
## Anatomy
thumb\|upright=1.4\|Structure of a typical neuron in the peripheral nervous system
Axons are the primary transmission lines of the nervous system, and as bundles they form nerves in the peripheral nervous system, or nerve tracts in the central nervous system (CNS). Some axons can extend up to one meter or more while others extend as little as one millimeter. The longest axons in the human body are those of the sciatic nerve, which run from the base of the spinal cord to the big toe of each foot. The diameter of axons is also variable. Most individual axons are microscopic in diameter (typically about one micrometer (μm) across). The largest mammalian axons can reach a diameter of up to 20 μm. The squid giant axon, which is specialized to conduct signals very rapidly, is close to 1 millimeter in diameter, the size of a small pencil lead. The numbers of axonal telodendria (the branching structures at the end of the axon) can also differ from one nerve fiber to the next. Axons in the CNS typically show multiple telodendria, with many synaptic end points. In comparison, the cerebellar granule cell axon is characterized by a single T-shaped branch node from which two parallel fibers extend. Elaborate branching allows for the simultaneous transmission of messages to a large number of target neurons within a single region of the brain.
There are two types of axons in the nervous system: myelinated and unmyelinated axons. Myelin is a layer of a fatty insulating substance, which is formed by two types of glial cells: Schwann cells and oligodendrocytes. In the peripheral nervous system Schwann cells form the myelin sheath of a myelinated axon. Oligodendrocytes form the insulating myelin in the CNS. Along myelinated nerve fibers, gaps in the myelin sheath known as nodes of Ranvier occur at evenly spaced intervals. The myelination enables an especially rapid mode of electrical impulse propagation called saltatory conduction.
The myelinated axons from the cortical neurons form the bulk of the neural tissue called white matter in the brain. The myelin gives the white appearance to the tissue in contrast to the grey matter of the cerebral cortex which contains the neuronal cell bodies. A similar arrangement is seen in the cerebellum. Bundles of myelinated axons make up the nerve tracts in the CNS, and where they cross the midline of the brain to connect opposite regions they are called commissures. The largest of these is the corpus callosum that connects the two cerebral hemispheres, and this has around 20 million axons.
The structure of a neuron is seen to consist of two separate functional regions, or compartments`{{Snd}}`{=mediawiki}the cell body together with the dendrites as one region, and the axonal region as the other.
### Axonal region {#axonal_region}
The axonal region or compartment, includes the axon hillock, the initial segment, the rest of the axon, and the axon telodendria, and axon terminals. It also includes the myelin sheath. The Nissl bodies that produce the neuronal proteins are absent in the axonal region. Proteins needed for the growth of the axon, and the removal of waste materials, need a framework for transport. This axonal transport is provided for in the axoplasm by arrangements of microtubules and type IV intermediate filaments known as neurofilaments.
#### Axon hillock {#axon_hillock}
thumb\|right\|upright=1.75\|Detail showing microtubules at axon hillock and initial segment The axon hillock is the area formed from the cell body of the neuron as it extends to become the axon. It precedes the initial segment. The received action potentials that are summed in the neuron are transmitted to the axon hillock for the generation of an action potential from the initial segment.
#### Axonal initial segment {#axonal_initial_segment}
The **axonal initial segment** (AIS) is a structurally and functionally separate microdomain of the axon. One function of the initial segment is to separate the main part of an axon from the rest of the neuron; another function is to help initiate action potentials. Both of these functions support neuron cell polarity, in which dendrites (and, in some cases the soma) of a neuron receive input signals at the basal region, and at the apical region the neuron\'s axon provides output signals.
The axon initial segment is unmyelinated and contains a specialized complex of proteins. It is between approximately 20 and 60 μm in length and functions as the site of action potential initiation. Both the position on the axon and the length of the AIS can change showing a degree of plasticity that can fine-tune the neuronal output. A longer AIS is associated with a greater excitability. Plasticity is also seen in the ability of the AIS to change its distribution and to maintain the activity of neural circuitry at a constant level.
The AIS is highly specialized for the fast conduction of nerve impulses. This is achieved by a high concentration of voltage-gated sodium channels in the initial segment where the action potential is initiated. The ion channels are accompanied by a high number of cell adhesion molecules and scaffold proteins that anchor them to the cytoskeleton. Interactions with ankyrin-G are important as it is the major organizer in the AIS.
In other cases as seen in rat studies an axon originates from a dendrite; such axons are said to have \"dendritic origin\". Some axons with dendritic origin similarly have a \"proximal\" initial segment that starts directly at the axon origin, while others have a \"distal\" initial segment, discernibly separated from the axon origin. In many species some of the neurons have axons that emanate from the dendrite and not from the cell body, and these are known as axon-carrying dendrites. In many cases, an axon originates at an axon hillock on the soma; such axons are said to have \"somatic origin\". Some axons with somatic origin have a \"proximal\" initial segment adjacent the axon hillock, while others have a \"distal\" initial segment, separated from the soma by an extended axon hillock.
### Axonal transport {#axonal_transport}
The axoplasm is the equivalent of cytoplasm in the cell. Microtubules form in the axoplasm at the axon hillock. They are arranged along the length of the axon, in overlapping sections, and all point in the same direction`{{Snd}}`{=mediawiki}towards the axon terminals. This is noted by the positive endings of the microtubules. This overlapping arrangement provides the routes for the transport of different materials from the cell body. Studies on the axoplasm has shown the movement of numerous vesicles of all sizes to be seen along cytoskeletal filaments`{{Snd}}`{=mediawiki}the microtubules, and neurofilaments, in both directions between the axon and its terminals and the cell body.
Outgoing anterograde transport from the cell body along the axon, carries mitochondria and membrane proteins needed for growth to the axon terminal. Ingoing retrograde transport carries cell waste materials from the axon terminal to the cell body. Outgoing and ingoing tracks use different sets of motor proteins. Outgoing transport is provided by kinesin, and ingoing return traffic is provided by dynein. Dynein is minus-end directed. There are many forms of kinesin and dynein motor proteins, and each is thought to carry a different cargo. The studies on transport in the axon led to the naming of kinesin.
### Myelination
In the nervous system, axons may be myelinated, or unmyelinated. This is the provision of an insulating layer, called a myelin sheath. The myelin membrane is unique in its relatively high lipid to protein ratio.
In the peripheral nervous system axons are myelinated by glial cells known as Schwann cells. In the central nervous system the myelin sheath is provided by another type of glial cell, the oligodendrocyte. Schwann cells myelinate a single axon. An oligodendrocyte can myelinate up to 50 axons.
The composition of myelin is different in the two types. In the CNS the major myelin protein is proteolipid protein, and in the PNS it is myelin basic protein.
### Nodes of Ranvier {#nodes_of_ranvier}
Nodes of Ranvier (also known as *myelin sheath gaps*) are short unmyelinated segments of a myelinated axon, which are found periodically interspersed between segments of the myelin sheath. Therefore, at the point of the node of Ranvier, the axon is reduced in diameter. These nodes are areas where action potentials can be generated. In saltatory conduction, electrical currents produced at each node of Ranvier are conducted with little attenuation to the next node in line, where they remain strong enough to generate another action potential. Thus in a myelinated axon, action potentials effectively \"jump\" from node to node, bypassing the myelinated stretches in between, resulting in a propagation speed much faster than even the fastest unmyelinated axon can sustain.
### Axon terminals {#axon_terminals}
An axon can divide into many branches called telodendria (Greek for \'end of tree\'). At the end of each **telodendron** is an axon terminal (also called a terminal bouton or synaptic bouton, or end-foot). Axon terminals contain synaptic vesicles that store the neurotransmitter for release at the synapse. This makes multiple synaptic connections with other neurons possible. Sometimes the axon of a neuron may synapse onto dendrites of the same neuron, when it is known as an autapse. Some synaptic junctions appear along the length of an axon as it extends; these are called **en passant boutons** (\"in passing boutons\") and can be in the hundreds or even the thousands along one axon.
#### Axonal varicosities {#axonal_varicosities}
In the normally developed brain, along the shaft of some axons are located pre-synaptic boutons also known as **axonal varicosities** and these have been found in regions of the hippocampus that function in the release of neurotransmitters. However, axonal varicosities are also present in neurodegenerative diseases where they interfere with the conduction of an action potential. Axonal varicosities are also the hallmark of traumatic brain injuries. Axonal damage is usually to the axon cytoskeleton disrupting transport. As a consequence protein accumulations such as amyloid-beta precursor protein can build up in a swelling resulting in a number of varicosities along the axon.
## Action potentials {#action_potentials}
thumb\|upright=1.2\|Synaptic connections from an axon
Most axons carry signals in the form of action potentials, which are discrete electrochemical impulses that travel rapidly along an axon, starting at the cell body and terminating at points where the axon makes synaptic contact with target cells. The defining characteristic of an action potential is that it is \"all-or-nothing\"`{{Snd}}`{=mediawiki}every action potential that an axon generates has essentially the same size and shape. This all-or-nothing characteristic allows action potentials to be transmitted from one end of a long axon to the other without any reduction in size. There are, however, some types of neurons with short axons that carry graded electrochemical signals, of variable amplitude.
When an action potential reaches a presynaptic terminal, it activates the synaptic transmission process. The first step is rapid opening of calcium ion channels in the membrane of the axon, allowing calcium ions to flow inward across the membrane. The resulting increase in intracellular calcium concentration causes synaptic vesicles (tiny containers enclosed by a lipid membrane) filled with a neurotransmitter chemical to fuse with the axon\'s membrane and empty their contents into the extracellular space. The neurotransmitter is released from the presynaptic nerve through exocytosis. The neurotransmitter chemical then diffuses across to receptors located on the membrane of the target cell. The neurotransmitter binds to these receptors and activates them. Depending on the type of receptors that are activated, the effect on the target cell can be to excite the target cell, inhibit it, or alter its metabolism in some way. This entire sequence of events often takes place in less than a thousandth of a second. Afterward, inside the presynaptic terminal, a new set of vesicles is moved into position next to the membrane, ready to be released when the next action potential arrives. The action potential is the final electrical step in the integration of synaptic messages at the scale of the neuron.
Extracellular recordings of action potential propagation in axons has been demonstrated in freely moving animals. While extracellular somatic action potentials have been used to study cellular activity in freely moving animals such as place cells, axonal activity in both white and gray matter can also be recorded. Extracellular recordings of axon action potential propagation is distinct from somatic action potentials in three ways: 1. The signal has a shorter peak-trough duration (\~150μs) than of pyramidal cells (\~500μs) or interneurons (\~250μs). 2. The voltage change is triphasic. 3. Activity recorded on a tetrode is seen on only one of the four recording wires. In recordings from freely moving rats, axonal signals have been isolated in white matter tracts including the alveus and the corpus callosum as well hippocampal gray matter.
In fact, the generation of action potentials in vivo is sequential in nature, and these sequential spikes constitute the digital codes in the neurons. Although previous studies indicate an axonal origin of a single spike evoked by short-term pulses, physiological signals in vivo trigger the initiation of sequential spikes at the cell bodies of the neurons.
In addition to propagating action potentials to axonal terminals, the axon is able to amplify the action potentials, which makes sure a secure propagation of sequential action potentials toward the axonal terminal. In terms of molecular mechanisms, voltage-gated sodium channels in the axons possess lower threshold and shorter refractory period in response to short-term pulses.
## Development and growth {#development_and_growth}
### Development
The development of the axon to its target, is one of the six major stages in the overall development of the nervous system. Studies done on cultured hippocampal neurons suggest that neurons initially produce multiple neurites that are equivalent, yet only one of these neurites is destined to become the axon. It is unclear whether axon specification precedes axon elongation or vice versa, although recent evidence points to the latter. If an axon that is not fully developed is cut, the polarity can change and other neurites can potentially become the axon. This alteration of polarity only occurs when the axon is cut at least 10 μm shorter than the other neurites. After the incision is made, the longest neurite will become the future axon and all the other neurites, including the original axon, will turn into dendrites. Imposing an external force on a neurite, causing it to elongate, will make it become an axon. Nonetheless, axonal development is achieved through a complex interplay between extracellular signaling, intracellular signaling and cytoskeletal dynamics.
#### Extracellular signaling {#extracellular_signaling}
The extracellular signals that propagate through the extracellular matrix surrounding neurons play a prominent role in axonal development. These signaling molecules include proteins, neurotrophic factors, and extracellular matrix and adhesion molecules. Netrin (also known as UNC-6) a secreted protein, functions in axon formation. When the UNC-5 netrin receptor is mutated, several neurites are irregularly projected out of neurons and finally a single axon is extended anteriorly. The neurotrophic factors`{{Snd}}`{=mediawiki}nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF) and neurotrophin-3 (NTF3) are also involved in axon development and bind to Trk receptors.
The ganglioside-converting enzyme plasma membrane ganglioside sialidase (PMGS), which is involved in the activation of TrkA at the tip of neutrites, is required for the elongation of axons. PMGS asymmetrically distributes to the tip of the neurite that is destined to become the future axon.
#### Intracellular signaling {#intracellular_signaling}
During axonal development, the activity of PI3K is increased at the tip of destined axon. Disrupting the activity of PI3K inhibits axonal development. Activation of PI3K results in the production of phosphatidylinositol (3,4,5)-trisphosphate (PtdIns) which can cause significant elongation of a neurite, converting it into an axon. As such, the overexpression of phosphatases that dephosphorylate PtdIns leads into the failure of polarization.
#### Cytoskeletal dynamics {#cytoskeletal_dynamics}
The neurite with the lowest actin filament content will become the axon. PGMS concentration and f-actin content are inversely correlated; when PGMS becomes enriched at the tip of a neurite, its f-actin content is substantially decreased. In addition, exposure to actin-depolimerizing drugs and toxin B (which inactivates Rho-signaling) causes the formation of multiple axons. Consequently, the interruption of the actin network in a growth cone will promote its neurite to become the axon.
### Growth
Growing axons move through their environment via the growth cone, which is at the tip of the axon. The growth cone has a broad sheet-like extension called a lamellipodium which contain protrusions called filopodia. The filopodia are the mechanism by which the entire process adheres to surfaces and explores the surrounding environment. Actin plays a major role in the mobility of this system. Environments with high levels of cell adhesion molecules (CAMs) create an ideal environment for axonal growth. This seems to provide a \"sticky\" surface for axons to grow along. Examples of CAMs specific to neural systems include N-CAM, TAG-1`{{Snd}}`{=mediawiki}an axonal glycoprotein`{{Snd}}`{=mediawiki}and MAG, all of which are part of the immunoglobulin superfamily. Another set of molecules called extracellular matrix-adhesion molecules also provide a sticky substrate for axons to grow along. Examples of these molecules include laminin, fibronectin, tenascin, and perlecan. Some of these are surface bound to cells and thus act as short range attractants or repellents. Others are difusible ligands and thus can have long range effects.
Cells called guidepost cells assist in the guidance of neuronal axon growth. These cells that help axon guidance, are typically other neurons that are sometimes immature. When the axon has completed its growth at its connection to the target, the diameter of the axon can increase by up to five times, depending on the speed of conduction required.
It has also been discovered through research that if the axons of a neuron were damaged, as long as the soma (the cell body of a neuron) is not damaged, the axons would regenerate and remake the synaptic connections with neurons with the help of guidepost cells. This is also referred to as neuroregeneration.
Nogo-A is a type of neurite outgrowth inhibitory component that is present in the central nervous system myelin membranes (found in an axon). It has a crucial role in restricting axonal regeneration in adult mammalian central nervous system. In recent studies, if Nogo-A is blocked and neutralized, it is possible to induce long-distance axonal regeneration which leads to enhancement of functional recovery in rats and mouse spinal cord. This has yet to be done on humans. A recent study has also found that macrophages activated through a specific inflammatory pathway activated by the Dectin-1 receptor are capable of promoting axon recovery, also however causing neurotoxicity in the neuron.
### Length regulation {#length_regulation}
Axons vary largely in length from a few micrometers up to meters in some animals. This emphasizes that there must be a cellular length regulation mechanism allowing the neurons both to sense the length of their axons and to control their growth accordingly. It was discovered that motor proteins play an important role in regulating the length of axons. Based on this observation, researchers developed an explicit model for axonal growth describing how motor proteins could affect the axon length on the molecular level. These studies suggest that motor proteins carry signaling molecules from the soma to the growth cone and vice versa whose concentration oscillates in time with a length-dependent frequency.
## Classification
The axons of neurons in the human peripheral nervous system can be classified based on their physical features and signal conduction properties. Axons were known to have different thicknesses (from 0.1 to 20 μm) and these differences were thought to relate to the speed at which an action potential could travel along the axon`{{Snd}}`{=mediawiki}its *conductance velocity*. Erlanger and Gasser proved this hypothesis, and identified several types of nerve fiber, establishing a relationship between the diameter of an axon and its nerve conduction velocity. They published their findings in 1941 giving the first classification of axons.
Axons are classified in two systems. The first one introduced by Erlanger and Gasser, grouped the fibers into three main groups using the letters A, B, and C. These groups, group A, group B, and group C include both the sensory fibers (afferents) and the motor fibers (efferents). The first group A, was subdivided into alpha, beta, gamma, and delta fibers`{{Snd}}`{=mediawiki}Aα, Aβ, Aγ, and Aδ. The motor neurons of the different motor fibers, were the lower motor neurons`{{Snd}}`{=mediawiki}alpha motor neuron, beta motor neuron, and gamma motor neuron having the Aα, Aβ, and Aγ nerve fibers, respectively.
Later findings by other researchers identified two groups of Aa fibers that were sensory fibers. These were then introduced into a system (Lloyd classification) that only included sensory fibers (though some of these were mixed nerves and were also motor fibers). This system refers to the sensory groups as Types and uses Roman numerals: Type Ia, Type Ib, Type II, Type III, and Type IV.
### Motor
Lower motor neurons have two kind of fibers:
+------------------------+------------------+-----------+--------+----------------------+--------------------------+
| Type | Erlanger-Gasser\ | Diameter\ | Myelin | Conduction velocity\ | Associated muscle fibers |
| | Classification | (μm) | | (meters/second) | |
+========================+==================+===========+========+======================+==========================+
| Alpha (α) motor neuron | Aα | 13--20 | Yes | 80--120 | Extrafusal muscle fibers |
+------------------------+------------------+-----------+--------+----------------------+--------------------------+
| Beta (β) motor neuron | Aβ | | | | |
+------------------------+------------------+-----------+--------+----------------------+--------------------------+
| Gamma (γ) motor neuron | Aγ | 5-8 | Yes | 4--24 | Intrafusal muscle fibers |
+------------------------+------------------+-----------+--------+----------------------+--------------------------+
: Motor fiber types
### `{{Visible anchor|Sensory}}`{=mediawiki}
Different sensory receptors are innervated by different types of nerve fibers. Proprioceptors are innervated by type Ia, Ib and II sensory fibers, mechanoreceptors by type II and III sensory fibers and nociceptors and thermoreceptors by type III and IV sensory fibers.
+------+------------------+-----------+--------+----------------+---------------------------------------------------------------+----------------+----------------+------------------+
| Type | Erlanger-Gasser\ | Diameter\ | Myelin | Conduction\ | Associated sensory receptors | Proprioceptors | Mechanoceptors | Nociceptors and\ |
| | Classification | (μm) | | velocity (m/s) | | | | thermoreceptors |
+======+==================+===========+========+================+===============================================================+================+================+==================+
| Ia | Aα | 13--20 | Yes | 80--120 | Primary receptors of muscle spindle (annulospiral ending) | ✔ | | |
+------+------------------+-----------+--------+----------------+---------------------------------------------------------------+----------------+----------------+------------------+
| Ib | Aα | 13--20 | Yes | 80--120 | Golgi tendon organ | | | |
+------+------------------+-----------+--------+----------------+---------------------------------------------------------------+----------------+----------------+------------------+
| II | Aβ | 6--12 | Yes | 33--75 | Secondary receptors of muscle spindle (flower-spray ending).\ | | ✔ | |
| | | | | | All cutaneous mechanoreceptors | | | |
+------+------------------+-----------+--------+----------------+---------------------------------------------------------------+----------------+----------------+------------------+
| III | Aδ | 1--5 | Thin | 3--30 | Free nerve endings of touch and pressure\ | | | ✔ |
| | | | | | Nociceptors of lateral spinothalamic tract\ | | | |
| | | | | | Cold thermoreceptors | | | |
+------+------------------+-----------+--------+----------------+---------------------------------------------------------------+----------------+----------------+------------------+
| IV | C | 0.2--1.5 | No | 0.5--2.0 | Nociceptors of anterior spinothalamic tract\ | | | |
| | | | | | Warmth receptors | | | |
+------+------------------+-----------+--------+----------------+---------------------------------------------------------------+----------------+----------------+------------------+
: Sensory fiber types
### Autonomic
The autonomic nervous system has two kinds of peripheral fibers:
+-----------------------+------------------+-----------+--------+----------------+
| Type | Erlanger-Gasser\ | Diameter\ | Myelin | Conduction\ |
| | Classification | (μm) | | velocity (m/s) |
+=======================+==================+===========+========+================+
| preganglionic fibers | B | 1--5 | Yes | 3--15 |
+-----------------------+------------------+-----------+--------+----------------+
| postganglionic fibers | C | 0.2--1.5 | No | 0.5--2.0 |
+-----------------------+------------------+-----------+--------+----------------+
: Fiber types
## Clinical significance {#clinical_significance}
In order of degree of severity, injury to a nerve in the peripheral nervous system can be described as neurapraxia, axonotmesis, or neurotmesis. Concussion is considered a mild form of diffuse axonal injury. Axonal injury can also cause central chromatolysis. The dysfunction of axons in the nervous system is one of the major causes of many inherited and acquired neurological disorders that affect both peripheral and central neurons.
When an axon is crushed, an active process of axonal degeneration takes place at the part of the axon furthest from the cell body. This degeneration takes place quickly following the injury, with the part of the axon being sealed off at the membranes and broken down by macrophages. This is known as Wallerian degeneration. Dying back of an axon can also take place in many neurodegenerative diseases, particularly when axonal transport is impaired, this is known as Wallerian-like degeneration. Studies suggest that the degeneration happens as a result of the axonal protein NMNAT2, being prevented from reaching all of the axon.
Demyelination of axons causes the multitude of neurological symptoms found in the disease multiple sclerosis.
Dysmyelination is the abnormal formation of the myelin sheath. This is implicated in several leukodystrophies, and also in schizophrenia.
A severe traumatic brain injury can result in widespread lesions to nerve tracts damaging the axons in a condition known as diffuse axonal injury. This can lead to a persistent vegetative state. It has been shown in studies on the rat that axonal damage from a single mild traumatic brain injury, can leave a susceptibility to further damage, after repeated mild traumatic brain injuries.
A nerve guidance conduit is an artificial means of guiding axon growth to enable neuroregeneration, and is one of the many treatments used for different kinds of nerve injury.
## Terminology
Some general dictionaries define \"nerve fiber\" as any neuronal process, including both axons and dendrites. However, medical sources generally use \"nerve fiber\" to refer to the axon only.
## History
German anatomist Otto Friedrich Karl Deiters is generally credited with the discovery of the axon by distinguishing it from the dendrites. Swiss Rüdolf Albert von Kölliker and German Robert Remak were the first to identify and characterize the axon initial segment. Kölliker named the axon in 1896. Louis-Antoine Ranvier was the first to describe the gaps or nodes found on axons and for this contribution these axonal features are now commonly referred to as the nodes of Ranvier. Santiago Ramón y Cajal, a Spanish anatomist, proposed that axons were the output components of neurons, describing their functionality. Joseph Erlanger and Herbert Gasser earlier developed the classification system for peripheral nerve fibers, based on axonal conduction velocity, myelination, fiber size etc. Alan Hodgkin and Andrew Huxley also employed the squid giant axon (1939) and by 1952 they had obtained a full quantitative description of the ionic basis of the action potential, leading to the formulation of the Hodgkin--Huxley model. Hodgkin and Huxley were awarded jointly the Nobel Prize for this work in 1963. The formulae detailing axonal conductance were extended to vertebrates in the Frankenhaeuser--Huxley equations. The understanding of the biochemical basis for action potential propagation has advanced further, and includes many details about individual ion channels.
## Other animals {#other_animals}
The axons in invertebrates have been extensively studied. The longfin inshore squid, often used as a model organism has the longest known axon. The giant squid has the largest axon known. Its size ranges from 0.5 (typically) to 1 mm in diameter and is used in the control of its jet propulsion system. The fastest recorded conduction speed of 210 m/s, is found in the ensheathed axons of some pelagic Penaeid shrimps and the usual range is between 90 and 200 meters/s (cf 100--120 m/s for the fastest myelinated vertebrate axon.)
## Additional images {#additional_images}
<File:Example> of Waveforms from Extracellular Tetrode Recordings in the Hippocampus from Different Cell Types and Axons.tif\|Recordings in the hippocampus from different cell types and axons
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American shot
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An **American shot** or **cowboy shot** is a medium-long (\"knee\") film shot of a group of characters, who are arranged so that all are visible to the camera. It is a translation of a phrase from French film criticism, **plan américain*.* The usual arrangement is for the actors to stand in an irregular line from one side of the screen to the other, with the actors at the end coming forward a little and standing more in profile than the others. The purpose of the composition is to allow complex dialogue scenes to be played out without changes in camera position. In some literature, this is simply referred to as a 3/4 shot.
One of the other main reasons why French critics called it \"American shot\" was its frequent use in the western genre. This was because a shot that started at knee level would reveal the weapon of a cowboy, usually holstered at their waist. It is the closest the camera can get to an actor while keeping both their face and their holstered gun in frame.
The French critics thought it was characteristic of American films of the 1930s or 1940s; however, it was mostly characteristic of cheaper American movies, such as Charlie Chan mysteries where people collected in front of a fireplace or at the foot of the stairs in order to explain what happened a few minutes ago.
Howard Hawks legitimized this style in his films, allowing characters to act, even when not talking, when most of the audience would not be paying attention. It became his trademark style.
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August Derleth
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**August William Derleth** (February 24, 1909 -- July 4, 1971) was an American writer and anthologist. He was the first book publisher of the writings of H. P. Lovecraft. He made contributions to the Cthulhu Mythos and the cosmic horror genre and helped found Arkham House, a publishing company which did much to introduce hardcover prints of United Kingdom supernatural fiction works to the United States. Derleth was also a leading American regional writer of his day, as well as prolific in several other genres, including historical fiction, poetry, detective fiction, science fiction, and biography. Notably, he created the fictional detective Solar Pons, a pastiche of Arthur Conan Doyle\'s Sherlock Holmes.
A 1938 Guggenheim Fellow, Derleth considered his most serious work to be the ambitious *Sac Prairie Saga*, a series of fiction, historical fiction, poetry, and non-fiction naturalist works designed to memorialize life in the Wisconsin he knew. Derleth can also be considered a pioneering naturalist and conservationist in his writing.
## Life
The son of William Julius Derleth and Rose Louise Volk, Derleth grew up in Sauk City, Wisconsin. He was educated in local parochial and public high school. Derleth wrote his first fiction at age 13. He was interested most in reading, and he made three trips to the library a week. He would save his money to buy books (his personal library exceeded 12,000 volumes later on in life). Some of his biggest influences were Ralph Waldo Emerson\'s essays, Walt Whitman, H. L. Mencken\'s *The American Mercury*, Samuel Johnson\'s *The History of Rasselas, Prince of Abissinia*, Alexandre Dumas, Edgar Allan Poe, Walter Scott, and Henry David Thoreau\'s Walden.
Forty rejected stories and three years later, according to anthologist Jim Stephens, he sold his first story, \"Bat\'s Belfry\", to *Weird Tales* magazine in 1926. Derleth wrote throughout his four years at the University of Wisconsin, where he received a B.A. in 1930. During this time he also served briefly as associate editor of Minneapolis-based Fawcett Publications *Mystic Magazine*.
Returning to Sauk City in the summer of 1931, Derleth worked in a local canning factory and collaborated with childhood friend Mark Schorer (later Chairman of the University of California, Berkeley English Department). They rented a cabin, writing Gothic and other horror stories and selling them to *Weird Tales* magazine. Derleth won a place on the O\'Brien Roll of Honor for *Five Alone*, published in *Place of Hawks*, but was first published in *Pagany* magazine.
As a result of his early work on the *Sac Prairie Saga*, Derleth was awarded the prestigious Guggenheim Fellowship; his sponsors were Helen C. White, Nobel Prize-winning novelist Sinclair Lewis and poet Edgar Lee Masters of *Spoon River Anthology* fame.
In the mid-1930s, Derleth organized a Ranger\'s Club for young people, served as clerk and president of the local school board, served as a parole officer, organized a local men\'s club and a parent-teacher association. He also lectured in American regional literature at the University of Wisconsin and was a contributing editor of *Outdoors Magazine*.
With longtime friend Donald Wandrei, Derleth founded Arkham House in 1939. Its initial objective was to publish the works of H. P. Lovecraft, with whom Derleth had corresponded since his teenage years. At the same time, he began teaching a course in American Regional Literature at the University of Wisconsin.
In 1941, he became literary editor of *The Capital Times* newspaper in Madison, a post he held until his resignation in 1960. His hobbies included fencing, swimming, chess, philately and comic-strips (Derleth reportedly used the funding from his Guggenheim Fellowship to bind his comic book collection, most recently valued in the millions of dollars, rather than to travel abroad as the award intended.). Derleth\'s true avocation, however, was hiking the terrain of his native Wisconsin lands, and observing and recording nature with an expert eye.
Derleth once wrote of his writing methods, \"I write very swiftly, from 750,000 to a million words yearly, very little of it pulp material.\"
In 1948, he was elected president of the Associated Fantasy Publishers at the 6th World Science Fiction Convention in Toronto.
He was married April 6, 1953, to Sandra Evelyn Winters. They divorced six years later. Derleth retained custody of the couple\'s two children, April Rose Derleth and Walden William Derleth. April earned a Bachelor of Arts degree in English from the University of Wisconsin-Madison in 1977. She became majority stockholder, President, and CEO of Arkham House in 1994. She remained in that capacity until her death. She was known in the community as a naturalist and humanitarian. April died on March 21, 2011.
In 1960, Derleth began editing and publishing a magazine called *Hawk and Whippoorwill*, dedicated to poems of man and nature.
Derleth died of a heart attack on July 4, 1971, and is buried in St. Aloysius Cemetery in Sauk City. The U.S. 12 bridge over the Wisconsin River is named in his honor. Derleth was Roman Catholic.
In Derleth\'s biography, Dorothy M. Grobe Litersky stated that Derleth was bisexual, and maintained long-term romantic relationships with both men and women. This assertion has not been verified; no names were given of these romantic partners (in the interest of privacy according to Litersky), and no evidence or acknowledgement of Derleth having a bisexual or homosexual orientation has ever been found in his personal correspondence.
## Career
Derleth wrote more than 150 short stories and more than 100 books during his lifetime.
### The *Sac Prairie Saga* {#the_sac_prairie_saga}
Derleth wrote an expansive series of novels, short stories, journals, poems, and other works about Sac Prairie. Derleth intended this series to comprise up to 50 novels telling the projected life-story of the region from the 19th century onwards, with analogies to Balzac\'s *Human Comedy* and Proust\'s *Remembrance of Things Past*.
This, and other early work by Derleth, made him a well-known figure among the regional literary figures of his time: early Pulitzer Prize winners Hamlin Garland and Zona Gale, as well as Sinclair Lewis, the last both an admirer and critic of Derleth.
As Edward Wagenknecht wrote in *Cavalcade of the American Novel*, \"What Mr. Derleth has that is lacking... in modern novelists generally, is a country. He belongs. He writes of a land and a people that are bone of his bone and flesh of his flesh. In his fictional world, there is a unity much deeper and more fundamental than anything that can be conferred by an ideology. It is clear, too, that he did not get the best, and most fictionally useful, part of his background material from research in the library; like Scott, in his Border novels, he gives, rather, the impression of having drunk it in with his mother\'s milk.\"
Jim Stephens, editor of *An August Derleth Reader*, (1992), argues: \"what Derleth accomplished... was to gather a Wisconsin mythos which gave respect to the ancient fundament of our contemporary life.\"
The author inaugurated the *Sac Prairie Saga* with four novellas comprising *Place of Hawks*, published by Loring & Mussey in 1935. At publication, *The Detroit News* wrote: \"Certainly with this book Mr. Derleth may be added to the American writers of distinction.\"
Derleth\'s first novel, *Still is the Summer Night*, was published two years later by the famous Charles Scribners\' editor Maxwell Perkins, and was the second in his Sac Prairie Saga.
*Village Year*, the first in a series of journals -- meditations on nature, Midwestern village American life, and more -- was published in 1941 to praise from *The New York Times Book Review*: \"A book of instant sensitive responsiveness... recreates its scene with acuteness and beauty, and makes an unusual contribution to the Americana of the present day.\" The *New York Herald Tribune* observed that \"Derleth... deepens the value of his village setting by presenting in full the enduring natural background; with the people projected against this, the writing comes to have the quality of an old Flemish picture, humanity lively and amusing and loveable in the foreground and nature magnificent beyond.\" James Grey, writing in the *St. Louis Dispatch* concluded, \"Derleth has achieved a kind of prose equivalent of the *Spoon River Anthology*.\"
In the same year, *Evening in Spring* was published by Charles Scribners & Sons. This work Derleth considered among his finest. What *The Milwaukee Journal* called \"this beautiful little love story\", is an autobiographical novel of first love beset by small-town religious bigotry. The work received critical praise: *The New Yorker* considered it a story told \"with tenderness and charm\", while the *Chicago Tribune* concluded: \"It\'s as though he turned back the pages of an old diary and told, with rekindled emotion, of the pangs of pain and the sharp, clear sweetness of a boy\'s first love.\" Helen Constance White, wrote in *The Capital Times* that it was \"... the best articulated, the most fully disciplined of his stories.\"
These were followed in 1943 with *Shadow of Night*, a Scribners\' novel of which *The Chicago Sun* wrote: \"Structurally it has the perfection of a carved jewel.... A psychological novel of the first order, and an adventure tale that is unique and inspiriting.\"
In November 1945, however, Derleth\'s work was attacked by his one-time admirer and mentor, Sinclair Lewis. Writing in *Esquire*, Lewis observed, \"It is a proof of Mr. Derleth\'s merit that he makes one want to make the journey and see his particular Avalon: The Wisconsin River shining among its islands, and the castles of Baron Pierneau and Hercules Dousman. He is a champion and a justification of regionalism. Yet he is also a burly, bounding, bustling, self-confident, opinionated, and highly-sweatered young man with faults so grievous that a melancholy perusal of them may be of more value to apprentices than a study of his serious virtues. If he could ever be persuaded that he isn\'t half as good as he thinks he is, if he would learn the art of sitting still and using a blue pencil, he might become twice as good as he thinks he is -- which would about rank him with Homer.\" Derleth good-humoredly reprinted the criticism along with a photograph of himself sans sweater, on the back cover of his 1948 country journal: *Village Daybook*.
A lighter side to the *Sac Prairie Saga* is a series of quasi-autobiographical short stories known as the \"Gus Elker Stories\", amusing tales of country life that Peter Ruber, Derleth\'s last editor, said were \"... models of construction and... fused with some of the most memorable characters in American literature.\" Most were written between 1934 and the late 1940s, though the last, \"Tail of the Dog\", was published in 1959 and won the *Scholastic Magazine* short story award for the year. The series was collected and republished in *Country Matters* in 1996.
*Walden West*, published in 1961, is considered by many Derleth\'s finest work. This prose meditation is built out of the same fundamental material as the series of Sac Prairie journals, but is organized around three themes: \"the persistence of memory... the sounds and odors of the country... and Thoreau\'s observation that the \'mass of men lead lives of quiet desperation.{{\'\"}} A blend of nature writing, philosophic musings, and careful observation of the people and place of \"Sac Prairie\". Of this work, George Vukelich, author of \"North Country Notebook\", writes: \"Derleth\'s *Walden West* is... the equal of Sherwood Anderson\'s *Winesburg,Ohio*, Thornton Wilder\'s *Our Town*, and Edgar Lee Masters\' *Spoon River Anthology*.\" This was followed eight years later by *Return to Walden West*, a work of similar quality, but with a more noticeable environmentalist edge to the writing, notes critic Norbert Blei.
A close literary relative of the *Sac Prairie Saga* was Derleth\'s *Wisconsin Saga*, which comprises several historical novels.
### Detective fiction and \"Solar Pons\" {#detective_fiction_and_solar_pons}
Detective fiction represented another substantial body of Derleth\'s work. Most notable among this work was a series of 70 stories in affectionate pastiche of Sherlock Holmes, whose creator, Sir Arthur Conan Doyle, he admired greatly. The stories feature a Holmes-styled British detective named Solar Pons, of 7B Praed Street in London. These included one published novel as well (*Mr. Fairlie\'s Final Journey*). The series was greatly admired by such notable writers and critics of mystery and detective fiction as Ellery Queen (Frederic Dannay), Anthony Boucher, Vincent Starrett, and Howard Haycraft.
In his 1944 volume *The Misadventures of Sherlock Holmes*, Ellery Queen wrote of Derleth\'s \"The Norcross Riddle\", an early Pons story: \"How many budding authors, not even old enough to vote, could have captured the spirit and atmosphere with as much fidelity?\" Queen adds, \"his choice of the euphonic Solar Pons is an appealing addition to the fascinating lore of Sherlockian nomenclature.\" Vincent Starrett, in his foreword to the 1964 edition of *The Casebook of Solar Pons*, wrote that the series is \"as sparkling a galaxy of Sherlockian pastiches as we have had since the canonical entertainments came to an end.\"
Despite close similarities to Doyle\'s creation, Pons lived in the post-World War I era, in the decades of the 1920s and 1930s. Though Derleth never wrote a Pons novel to equal *The Hound of the Baskervilles*, editor Peter Ruber wrote that \"Derleth produced more than a few Solar Pons stories almost as good as Sir Arthur\'s, and many that had better plot construction.\"
Although these stories were a form of diversion for Derleth, Ruber, who edited *The Original Text Solar Pons Omnibus Edition* (2000), argued: \"Because the stories were generally of such high quality, they ought to be assessed on their own merits as a unique contribution in the annals of mystery fiction, rather than suffering comparison as one of the endless imitators of Sherlock Holmes.\"
Some of the stories were self-published, through a new imprint called \"Mycroft & Moran\", an appellation of humorous significance to Holmesian scholars. For approximately a decade, an active supporting group was the Praed Street Irregulars, patterned after the Baker Street Irregulars.
In 1946, Conan Doyle\'s two sons made some attempts to force Derleth to cease publishing the Solar Pons series, but the efforts were unsuccessful, and were eventually withdrawn.
Derleth\'s mystery and detective fiction also included a series of works set in Sac Prairie and featuring Judge Peck as the central character.
### Youth and children\'s fiction {#youth_and_childrens_fiction}
Derleth wrote many and varied children\'s works, including biographies meant to introduce younger readers to explorer Jacques Marquette, as well as Ralph Waldo Emerson and Henry David Thoreau. Arguably most important among his works for younger readers, however, is the Steve and Sim Mystery Series, also known as the Mill Creek Irregulars series. The ten-volume series, published between 1958 and 1970, is set in Sac Prairie of the 1920s and can thus be considered in its own right a part of the *Sac Prairie Saga*, as well as an extension of Derleth\'s body of mystery fiction. Robert Hood, writing in the *New York Times* said: \"Steve and Sim, the major characters, are twentieth-century cousins of Huck Finn and Tom Sawyer; Derleth\'s minor characters, little gems of comic drawing.\" The first novel in the series, *The Moon Tenders*, does, in fact, involve a rafting adventure down the Wisconsin River, which led regional writer Jesse Stuart to suggest the novel was one that \"older people might read to recapture the spirit and dream of youth.\" The connection to the *Sac Prairie Saga* was noted by the *Chicago Tribune*: \"Once again a small midwest community in 1920s is depicted with perception, skill, and dry humor.\"
### Arkham House and the \"Cthulhu Mythos\" {#arkham_house_and_the_cthulhu_mythos}
Derleth was a correspondent and friend of H. P. Lovecraft -- when Lovecraft wrote about \"le Comte d\'Erlette\" in his fiction, it was in homage to Derleth. Derleth invented the term \"Cthulhu Mythos\" to describe the fictional universe depicted in the series of stories shared by Lovecraft and other writers in his circle.
When Lovecraft died in 1937, Derleth and Donald Wandrei assembled a collection of Lovecraft\'s stories and tried to get them published. Existing publishers showed little interest, so Derleth and Wandrei founded Arkham House in 1939 for that purpose. The name of the company derived from Lovecraft\'s fictional town of Arkham, Massachusetts, which features in many of his stories. In 1939, Arkham House published *The Outsider and Others*, a huge collection that contained most of Lovecraft\'s known short stories. Derleth and Wandrei soon expanded Arkham House and began a regular publishing schedule after its second book, *Someone in the Dark*, a collection of some of Derleth\'s own horror stories, was published in 1941.
Following Lovecraft\'s death, Derleth wrote a number of stories based on fragments and notes left by Lovecraft. These were published in *Weird Tales* and later in book form, under the byline \"H. P. Lovecraft and August Derleth\", with Derleth calling himself a \"posthumous collaborator\". This practice has raised objections in some quarters that Derleth simply used Lovecraft\'s name to market what was essentially his own fiction; S. T. Joshi refers to the \"posthumous collaborations\" as marking the beginning of \"perhaps the most disreputable phase of Derleth\'s activities\".
Dirk W. Mosig, S. T. Joshi, and Richard L. Tierney were dissatisfied with Derleth\'s invention of the term *Cthulhu Mythos* (Lovecraft himself used *Yog-Sothothery*) and his presentation of Lovecraft\'s fiction as having an overall pattern reflecting Derleth\'s own Christian world view, which they contrast with Lovecraft\'s depiction of an amoral universe. However, Robert M. Price points out that while Derleth\'s tales are distinct from Lovecraft\'s in their use of hope and his depiction of a struggle between good and evil, nevertheless the basis of Derleth\'s systemization are found in Lovecraft. He also suggests that the differences can be overstated:
> Derleth *was* more optimistic than Lovecraft in his conception of the Mythos, but we are dealing with a difference more of degree than kind. There are indeed tales wherein Derleth\'s protagonists get off scot-free (like \"The Shadow in the Attic\", \"Witches\' Hollow\", or \"The Shuttered Room\"), but often the hero is doomed (e.g., \"The House in the Valley\", \"The Peabody Heritage\", \"Something in Wood\"), as in Lovecraft. And it must be remembered that an occasional Lovecraftian hero does manage to overcome the odds, e.g., in \"The Horror in the Museum\", \"The Shunned House\", and \"The Case of Charles Dexter Ward\".
Derleth also treated Lovecraft\'s Great Old Ones as representatives of elemental forces, creating new fictional entities to flesh out this framework.
Such debates aside, Derleth\'s founding of Arkham House and his successful effort to rescue Lovecraft from literary oblivion are widely acknowledged by practitioners in the horror field as seminal events in the field. For instance, Ramsey Campbell has acknowledged Derleth\'s encouragement and guidance during the early part of his own writing career, and Kirby McCauley has cited Derleth and Arkham House as an inspiration for his own anthology *Dark Forces*. Arkham House and Derleth published *Dark Carnival*, the first book by Ray Bradbury, as well. Brian Lumley cites the importance of Derleth to his own Lovecraftian work, and contends in a 2009 introduction to Derleth\'s work that he was \"... one of the first, finest, and most discerning editors and publishers of macabre fiction\".
Important as was Derleth\'s work to rescue H.P. Lovecraft from literary obscurity at the time of Lovecraft\'s death, Derleth also built a body of horror and spectral fiction of his own; still frequently anthologized. The best of this work, recently reprinted in four volumes of short stories -- most of which were originally published in *Weird Tales*, illustrates Derleth\'s original abilities in the genre. While Derleth considered his work in this genre less important than his most serious literary efforts, the compilers of these four anthologies, including Ramsey Campbell, note that the stories still resonate after more than 50 years.
In 2009, The Library of America selected Derleth\'s story *The Panelled Room* for inclusion in its two-century retrospective of American Fantastic Tales.
### Other works {#other_works}
Derleth also wrote many historical novels, as part of both the *Sac Prairie Saga* and the *Wisconsin Saga*. He also wrote history; arguably most notable among these was *The Wisconsin: River of a Thousand Isles*, published in 1942. The work was one in a series entitled \"The Rivers of America\", conceived by writer Constance Lindsay Skinner during the Great Depression as a series that would connect Americans to their heritage through the history of the great rivers of the nation. Skinner wanted the series to be written by artists, not academicians. Derleth, while not a trained historian, was, according to former Wisconsin state historian William F. Thompson, \"... a very competent regional historian who based his historical writing upon research in the primary documents and who regularly sought the help of professionals...\". In the foreword to the 1985 reissue of the work by The University of Wisconsin Press, Thompson concluded: \"No other writer, of whatever background or training, knew and understood his particular \'corner of the earth\' better than August Derleth.\"
Additionally, Derleth wrote a number of volumes of poetry. Three of his collections -- *Rind of Earth* (1942), *Selected Poems* (1944), and *The Edge of Night* (1945) -- were published by the Decker Press, which also printed the work of other Midwestern poets such as Edgar Lee Masters.
Derleth was also the author of several biographies of other writers, including Zona Gale, Ralph Waldo Emerson and Henry David Thoreau.
He also wrote introductions to several collections of classic early 20th century comics, such as *Buster Brown*, *Little Nemo in Slumberland*, and *Katzenjammer Kids*, as well as a book of children\'s poetry entitled *A Boy\'s Way*, and the foreword to *Tales from an Indian Lodge* by Phebe Jewell Nichols*.* Derleth also wrote under the pen names Stephen Grendon, Kenyon Holmes and Tally Mason.
Derleth\'s papers were donated to the Wisconsin Historical Society in Madison.
## Awards
- O\'Brien Roll of Honour for short story, 1933
- Guggenheim fellow, 1938
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Applied ethics
|
*Practical Ethics*}} `{{Use dmy dates|date=February 2023}}`{=mediawiki} `{{more footnotes needed|date=September 2011}}`{=mediawiki} **Applied ethics** is the practical aspect of moral considerations. It is ethics with respect to real-world actions and their moral considerations in private and public life, the professions, health, technology, law, and leadership. For example, bioethics is concerned with identifying the best approach to moral issues in the life sciences, such as euthanasia, the allocation of scarce health resources, or the use of human embryos in research. Environmental ethics is concerned with ecological issues such as the responsibility of government and corporations to clean up pollution. Business ethics includes the duties of whistleblowers to the public and to their employers.
## History
Applied ethics has expanded the study of ethics beyond the realms of academic philosophical discourse. The field of applied ethics, as it appears today, emerged from debate surrounding rapid medical and technological advances in the early 1970s and is now established as a subdiscipline of moral philosophy. However, applied ethics is, by its very nature, a multi-professional subject because it requires specialist understanding of the potential ethical issues in fields like medicine, business or information technology. Nowadays, ethical codes of conduct exist in almost every profession.
An applied ethics approach to the examination of moral dilemmas can take many different forms but one of the most influential and most widely utilised approaches in bioethics and health care ethics is the four-principle approach developed by Tom Beauchamp and James Childress. The four-principle approach, commonly termed principlism, entails consideration and application of four prima facie ethical principles: autonomy, non-maleficence, beneficence, and justice.
## Underpinning theory {#underpinning_theory}
Applied ethics is distinguished from normative ethics, which concerns standards for right and wrong behavior, and from meta-ethics, which concerns the nature of ethical properties, statements, attitudes, and judgments.
Whilst these three areas of ethics appear to be distinct, they are also interrelated. The use of an applied ethics approach often draws upon these normative ethical theories:
1. Consequentialist ethics, which hold that the rightness of acts depends only on their consequences. The paradigmatic consequentialist theory is utilitarianism, which classically holds that whether an act is morally right depends on whether it maximizes net aggregated psychological wellbeing. This theory\'s main developments came from Jeremy Bentham and John Stuart Mill who distinguished between act and rule utilitarianism. Notable later developments were made by Henry Sidgwick who introduced the significance of motive or intent, and R. M. Hare who introduced the significance of preference in utilitarian decision-making. Other forms of consequentialism include prioritarianism.
2. Deontological ethics, which hold that acts have an inherent rightness or wrongness regardless of their context or consequences. This approach is epitomized by Immanuel Kant\'s notion of the categorical imperative, which was the centre of Kant\'s ethical theory based on duty. Another key deontological theory is natural law, which was heavily developed by Thomas Aquinas and is an important part of the Catholic Church\'s teaching on morals. Threshold deontology holds that rules ought to govern up to a point despite adverse consequences; but when the consequences become so dire that they cross a stipulated threshold, consequentialism takes over.
3. Virtue ethics, derived from Aristotle\'s and Confucius\' notions, which asserts that the right action will be that chosen by a suitably \'virtuous\' agent.
Normative ethical theories can clash when trying to resolve real-world ethical dilemmas. One approach attempting to overcome the divide between consequentialism and deontology is case-based reasoning, also known as casuistry. Casuistry does not begin with theory, rather it starts with the immediate facts of a real and concrete case. While casuistry makes use of ethical theory, it does not view ethical theory as the most important feature of moral reasoning. Casuists, like Albert Jonsen and Stephen Toulmin (*The Abuse of Casuistry*, 1988), challenge the traditional paradigm of applied ethics. Instead of starting from theory and applying theory to a particular case, casuists start with the particular case itself and then ask what morally significant features (including both theory and practical considerations) ought to be considered for that particular case. In their observations of medical ethics committees, Jonsen and Toulmin note that a consensus on particularly problematic moral cases often emerges when participants focus on the facts of the case, rather than on ideology or theory. Thus, a Rabbi, a Catholic priest, and an agnostic might agree that, in this particular case, the best approach is to withhold extraordinary medical care, while disagreeing on the reasons that support their individual positions. By focusing on cases and not on theory, those engaged in moral debate increase the possibility of agreement.
Applied ethics was later distinguished from the nascent applied epistemology, which is also under the umbrella of applied philosophy. While the former was concerned with the practical application of moral considerations, the latter focuses on the application of epistemology in solving practical problems.
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Analog signal
|
An **analog signal** (American English) or **analogue signal** (British and Commonwealth English) is any signal, typically a continuous-time signal, representing some other quantity, i.e., *analogous* to another quantity. For example, in an analog audio signal, the instantaneous signal voltage varies in a manner *analogous to* the pressure of the sound waves.
In contrast, a digital signal represents the original time-varying quantity as a sampled sequence of quantized numeric values, typically but not necessarily in the form of a binary value. Digital sampling imposes some bandwidth and dynamic range constraints on the representation and adds quantization noise.
The term *analog signal* usually refers to electrical signals; however, mechanical, pneumatic, hydraulic, and other systems may also convey or be considered analog signals.
## Representation
An analog signal uses some property of the medium to convey the signal\'s information. For example, an aneroid barometer uses rotary position as the signal to convey pressure information. In an electrical signal, the voltage, current, or frequency of the signal may be varied to represent the information.
Any information may be conveyed by an analog signal; such a signal may be a measured response to changes in a physical variable, such as sound, light, temperature, position, or pressure. The physical variable is converted to an analog signal by a transducer. For example, sound striking the diaphragm of a microphone induces corresponding fluctuations in the current produced by a coil in an electromagnetic microphone or the voltage produced by a condenser microphone. The voltage or the current is said to be an *analog* of the sound.`{{fact|date=December 2024}}`{=mediawiki}
## Noise
An analog signal is subject to electronic noise and distortion introduced by communication channels, recording and signal processing operations, which can progressively degrade the signal-to-noise ratio (SNR). As the signal is transmitted, copied, or processed, the unavoidable noise introduced in the signal path will accumulate as a generation loss, progressively and irreversibly degrading the SNR, until in extreme cases, the signal can be overwhelmed. Noise can show up as hiss and intermodulation distortion in audio signals, or snow in video signals. Generation loss is irreversible as there is no reliable method to distinguish the noise from the signal.`{{fact|date=December 2024}}`{=mediawiki} Note that, despite a popular misconception, analog representations do not provide \"infinite\" resolution or accuracy, due to this inevitable presence of noise (and therefore error) in any real-world system.
Converting an analog signal to digital form introduces a low-level quantization noise into the signal due to finite resolution of digital systems. Once in digital form, the signal can be transmitted, stored, and processed without introducing additional noise or distortion using error detection and correction.
Noise accumulation in analog systems can be minimized by electromagnetic shielding, balanced lines, low-noise amplifiers and high-quality electrical components.`{{fact|date=December 2024}}`{=mediawiki}
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1,005 |
August
|
Aug}} `{{pp-move-indef}}`{=mediawiki} `{{Use mdy dates|date=June 2013}}`{=mediawiki} `{{Calendar}}`{=mediawiki}
**August** is the eighth month of the year in the Julian and Gregorian calendars. Its length is 31 days.
In the Southern Hemisphere, August is the seasonal equivalent of February in the Northern Hemisphere. In the Northern Hemisphere, August falls in summer. In the Southern Hemisphere, the month falls during winter. In many European countries, August is the holiday month for most workers. Numerous religious holidays occurred during August in ancient Rome.
Certain meteor showers take place in August. The Kappa Cygnids occur in August, with yearly dates varying. The Alpha Capricornids meteor shower occurs as early as July 10 and ends around August 10. The Southern Delta Aquariids occur from mid-July to mid-August, with the peak usually around July 28--29. The Perseids, a major meteor shower, typically takes place between July 17 and August 24, with the peak days varying yearly. The star cluster of Messier 30 is best observed around August.
Among the aborigines of the Canary Islands, especially among the Guanches of Tenerife, the month of August received the name of Beñesmer or Beñesmen, which was also the harvest festival held that month.
The month was originally named *Sextilis* in Latin because it was the 6th month in the original ten-month Roman calendar under Romulus in 753 BC, with March being the first month of the year. About 700 BC, it became the eighth month when January and February were added to the year before March by King Numa Pompilius, who also gave it 29 days. Julius Caesar added two days when he created the Julian calendar in `{{auc|46|BC|main=greg}}`{=mediawiki}, giving it its modern length of 31 days.
In 8 BC, the month was renamed in honor of Emperor Augustus. According to a Senatus consultum quoted by Macrobius, he chose this month because it was the time of several of his great triumphs, including the conquest of Egypt. Commonly repeated lore has it that August has 31 days because Augustus wanted his month to match the length of Julius Caesar\'s July, but this is an invention of the 13th century scholar Johannes de Sacrobosco. Sextilis had 31 days before it was renamed. It was not chosen for its length.
## Symbols
August\'s birthstones are the peridot, sardonyx, and spinel. Its birth flower is the gladiolus or poppy, meaning beauty, strength of character, love, marriage and family. The Western zodiac signs are Leo (until August 22) and Virgo (from August 23 onward).
## Observances
*This list does not necessarily imply official status or general observance.*
### Non-Gregorian: `{{CURRENTYEAR}}`{=mediawiki} dates {#non_gregorian_dates}
(All Baha\'i, Islamic, and Jewish observances begin at sundown before the listed date and end at sundown on the date in question unless otherwise noted.)
- List of observances set by the Bahá\'í calendar
- List of observances set by the Chinese calendar
- List of observances set by the Hebrew calendar
- List of observances set by the Islamic calendar
- List of observances set by the Solar Hijri calendar
### Month-long {#month_long}
- Women\'s Month (South Africa)
- American Adventures Month (celebrates vacationing in the Americas)
- Children\'s Eye Health and Safety Month
- Digestive Tract Paralysis (DTP) Month
- Get Ready for Kindergarten Month
- Happiness Happens Month
- Month of Philippine Languages or Buwan ng Wika (Philippines)
- Neurosurgery Outreach Month
- Psoriasis Awareness Month
- Spinal Muscular Atrophy Awareness Month
- What Will Be Your Legacy Month
#### United States month-long {#united_states_month_long}
- National Black Business Month
- National Children\'s Vision and Learning Month
- National Immunization Awareness Month
- National Princess Peach Month
- National Water Quality Month
- National Win with Civility Month
##### Food months in the United States {#food_months_in_the_united_states}
- National Catfish Month
- National Dippin\' Dots Month
- Family Meals Month
- National Goat Cheese Month.
- National Panini Month
- Peach Month
- Sandwich Month
### Moveable Gregorian {#moveable_gregorian}
- National Science Week (Australia)
- See also Movable Western Christian observances
- See also Movable Eastern Christian observances
#### Second to last Sunday in July and the following two weeks {#second_to_last_sunday_in_july_and_the_following_two_weeks}
- Construction Holiday (Quebec)
#### 1st Saturday {#st_saturday}
- Food Day (Canada)
- Mead Day (United States)
- National Mustard Day (United States)
#### 1st Sunday {#st_sunday}
- Air Force Day (Ukraine)
- American Family Day (Arizona, United States)
- Children\'s Day (Uruguay)
- Friendship Day (United States)
- International Forgiveness Day
- Railway Workers\' Day (Russia)
#### First full week of August {#first_full_week_of_august}
- National Farmer\'s Market Week (United States)
#### 1st Monday {#st_monday}
- August Public Holiday (Ireland)
- Children\'s Day (Tuvalu)
- Civic Holiday (Canada)
- British Columbia Day (British Columbia, Canada)
- Natal Day (Nova Scotia, Canada)
- New Brunswick Day (New Brunswick, Canada)
- Saskatchewan Day (Saskatchewan, Canada
- Terry Fox Day (Manitoba, Canada)
- Commerce Day (Iceland)
- Emancipation Day (Anguilla, Antigua, The Bahamas, British Virgin Islands, Dominica, Grenada, Saint Kitts and Nevis)
- Farmer\'s Day (Zambia)
- Kadooment Day (Barbados)
- Labor Day (Samoa)
- National Day (Jamaica)
- Picnic Day (Northern Territory, Australia)
- Somers\' Day (Bermuda)
- Youth Day (Kiribati)
#### 1st Tuesday {#st_tuesday}
- National Night Out (United States)
#### 1st Friday {#st_friday}
- International Beer Day
#### 2nd Saturday {#nd_saturday}
- Sports Day (Russia)
#### Sunday on or closest to August 9 {#sunday_on_or_closest_to_august_9}
- National Peacekeepers\' Day (Canada)
#### 2nd Sunday {#nd_sunday}
- Children\'s Day (Argentina, Chile, Uruguay)
- Father\'s Day (Brazil, Samoa)
- Melon Day (Turkmenistan)
- Navy Day (Bulgaria)
- National Day (Singapore)
#### 2nd Monday {#nd_monday}
- Heroes\' Day (Zimbabwe)
- Victory Day (Hawaii and Rhode Island, United States)
#### 2nd Tuesday {#nd_tuesday}
- Defence Forces Day (Zimbabwe)
#### 3rd Saturday {#rd_saturday}
- National Honey Bee Day (United States)
#### 3rd Sunday {#rd_sunday}
- Children\'s Day (Argentina, Peru)
- Grandparents Day (Hong Kong)
#### 3rd Monday {#rd_monday}
- Discovery Day (Yukon, Canada)
- Day of Hearts (Haarlem and Amsterdam, Netherlands)
- National Mourning Day (Bangladesh)
#### 3rd Friday {#rd_friday}
- Hawaii Admission Day (Hawaii, United States)
#### Last Thursday {#last_thursday}
- National Burger Day (United Kingdom)
#### Last Sunday {#last_sunday}
- Coal Miner\'s Day (some former Soviet Union countries)
- National Grandparents Day (Taiwan)
#### Last Monday {#last_monday}
- Father\'s Day (South Sudan)
- National Heroes\' Day (Philippines)
- Liberation Day (Hong Kong)
- Late Summer Bank Holiday (England, Northern Ireland and Wales)
### Fixed Gregorian {#fixed_gregorian}
- Season of Emancipation (Barbados) (April 14 to August 23)
- International Clown Week (August 1--7)
- World Breastfeeding Week (August 1--7)
- August 1
- Armed Forces Day (China)
- Armed Forces Day (Lebanon)
- Azerbaijani Language and Alphabet Day (Azerbaijan)
- Emancipation Day (Barbados, Guyana, Jamaica, Saint Vincent and the Grenadines, St. Lucia, Trinidad and Tobago, Turks and Caicos Islands)
- Imbolc (Neopaganism, Southern Hemisphere only)
- Lammas (England, Scotland, Neopaganism, Northern Hemisphere only)
- Lughnasadh (Gaels, Ireland, Scotland, Neopaganism, Northern Hemisphere only)
- Minden Day (United Kingdom)
- National Day (Benin)
- National Milkshake Day (United States)
- Official Birthday and Coronation Day of the King of Tonga (Tonga)
- Pachamama Raymi (Quechua people in Ecuador and Peru)
- Parents\' Day (Democratic Republic of the Congo)
- Procession of the Cross and the beginning of Dormition Fast (Eastern Orthodoxy)
- Statehood Day (Colorado)
- Swiss National Day (Switzerland)
- Victory Day (Cambodia, Laos, Vietnam)
- World Scout Scarf Day
- Yorkshire Day (Yorkshire, England)
- August 2
- Airmobile Forces Day (Ukraine)
- Day of Azerbaijani cinema (Azerbaijan)
- Our Lady of the Angels Day (Costa Rica)
- Paratroopers Day (Russia)
- Republic Day (North Macedonia)
- August 3
- Anniversary of the Killing of Pidjiguiti (Guinea-Bissau)
- Armed Forces Day (Equatorial Guinea)
- Esther Day (United States)
- Flag Day (Venezuela)
- Independence Day (Niger)
- Arbor Day (Niger)
- National Guard Day (Venezuela)
- National Watermelon Day (United States)
- National White Wine Day (United States)
- August 4
- Coast Guard Day (United States)
- Constitution Day (Cook Islands)
- Matica slovenská Day (Slovakia)
- Revolution Day (Burkina Faso)
- August 5
- Dedication of the Basilica of St Mary Major (Catholic Church)
- Independence Day (Burkina Faso)
- National Underwear Day (United States)
- Victory and Homeland Thanksgiving Day and the Day of Croatian defenders (Croatia)
- August 6
- Feast of the Transfiguration
- Sheikh Zayed bin Sultan Al Nahyan\'s Accession Day. (United Arab Emirates)
- Hiroshima Peace Memorial Ceremony (Hiroshima, Japan)
- Independence Day (Bolivia)
- Independence Day (Jamaica)
- Russian Railway Troops Day (Russia)
- August 7
- Assyrian Martyrs Day (Assyrian community)
- Battle of Boyacá Day (Colombia)
- Emancipation Day (Saint Kitts and Nevis)
- Independence Day (Ivory Coast)
- Republic Day (Ivory Coast)
- Youth Day (Kiribati)
- August 8
- Ceasefire Day (Iraqi Kurdistan)
- Father\'s Day (Taiwan)
- Happiness Happens Day (International observance)
- International Cat Day
- Namesday of Queen Silvia of Sweden, (Sweden)
- Nane Nane Day (Tanzania)
- Signal Troops Day (Ukraine)
- August 9
- Battle of Gangut Day (Russia)
- International Day of the World\'s Indigenous People (United Nations)
- National Day (Singapore)
- National Women\'s Day (South Africa)
- Remembrance for Radbod, King of the Frisians (The Troth)
- August 10
- Argentine Air Force Day (Argentina)
- Constitution Day (Anguilla)
- Declaration of Independence of Quito (Ecuador)
- International Biodiesel Day
- National S\'more Day (United States)
- August 11
- Flag Day (Pakistan)
- Independence Day (Chad)
- Mountain Day (Japan)
- August 12
- Glorious Twelfth (United Kingdom)
- HM the Queen\'s Birthday and National Mother\'s Day (Thailand)
- International Youth Day (United Nations)
- Russian Railway Troops Day (Russia)
- Sea Org Day (Scientology)
- World Elephant Day
- August 13
- Independence Day (Central African Republic)
- International Lefthanders Day
- National Filet Mignon Day (United States)
- Women\'s Day (Tunisia)
- August 14
- Anniversary Day (Tristan da Cunha)
- Commemoration of Wadi al-Dahab (Morocco)
- Day of the Defenders of the Fatherland (Abkhazia)
- Engineer\'s Day (Dominican Republic)
- Falklands Day (Falkland Islands)
- Independence Day (Pakistan)
- National Creamsicle Day (United States)
- National Navajo Code Talkers Day (United States)
- Pramuka Day (Indonesia)
- August 15
- Feast Day of the Assumption of Mary (Catholic holy days of obligation, a public holiday in many countries.)
- Ferragosto (Italy)
- Māras (Latvia)
- Mother\'s Day (Antwerp and Costa Rica)
- National Acadian Day (Acadians)
- Virgin of Candelaria, patron of the Canary Islands. (Tenerife, Spain)
- Feast of the Dormition of the Theotokos (Eastern Orthodox, Oriental Orthodox and Eastern Catholic Churches)
- Navy Day (Romania)
- Armed Forces Day (Poland)
- The first day of Flooding of the Nile, or *Wafaa El-Nil* (Egypt and Coptic Church)
- The main day of Bon Festival (Japan), and its related observances:
- Awa Dance Festival (Tokushima Prefecture)
- Constitution Day (Equatorial Guinea)
- End-of-war Memorial Day, when the National Memorial Service for War Dead is held. (Japan)
- Founding of Asunción (Paraguay)
- Independence Day (Korea)
- Gwangbokjeol (South Korea)
- Jogukhaebangui nal, \"Fatherland Liberation Day\" (North Korea)
- Independence Day (India)
- Independence Day (Republic of the Congo)
- National Day (Liechtenstein)
- Victory over Japan Day (United Kingdom)
- National Lemon Meringue Pie Day (United States)
- August 16
- Bennington Battle Day (Vermont, United States)
- Children\'s Day (Paraguay)
- Gozan no Okuribi (Kyoto, Japan)
- The first day of the Independence Days (Gabon)
- National Airborne Day (United States)
- National Rum Day (United States)
- Restoration Day (Dominican Republic)
- August 17
- The Birthday of Marcus Garvey (Rastafari)
- Engineer\'s Day (Colombia)
- Flag Day (Bolivia)
- Independence Day (Indonesia)
- Independence Days (Gabon)
- National Vanilla Custard Day (United States)
- Prekmurje Union Day (Slovenia)
- San Martin Day (Argentina)
- August 18
- Arbor Day (Pakistan)
- Armed Forces Day (North Macedonia)
- Birthday of Virginia Dare (Roanoke Island)
- Constitution Day (Indonesia)
- Long Tan Day (Australia)
- National Science Day (Thailand)
- August 19
- Feast of the Transfiguration (Julian calendar), and its related observances:
- Buhe (Ethiopian Orthodox Tewahedo Church)
- Saviour\'s Transfiguration, popularly known as the \"Apples Feast\" (Russian Orthodox Church and Georgian Orthodox Church)
- Afghan Independence Day (Afghanistan)
- August Revolution Commemoration Day (Vietnam)
- Birthday of Crown Princess Mette-Marit (Norway)
- Manuel Luis Quezón Day (Quezon City and other places in The Philippines named after Manuel L. Quezon)
- National Aviation Day (United States)
- National Potato Day (United States)
- World Humanitarian Day
- August 20
- Indian Akshay Urja Day (India)
- Restoration of Independence Day (Estonia)
- Revolution of the King and People (Morocco)
- Saint Stephen\'s Day (Hungary)
- World Mosquito Day
- August 21
- Ninoy Aquino Day (Philippines)
- Youth Day/King Mohammed VI\'s Birthday (Morocco)
- August 22
- Feast of the Coronation of Mary
- Flag Day (Russia)
- Madras Day (Chennai and Tamil Nadu, India)
- National Eat a Peach Day (United States)
- National Pecan Torte Day (United States)
- August 23
- Battle of Kursk Day (Russia)
- Day of the National Flag (Ukraine)
- European Day of Remembrance for Victims of Stalinism and Nazism or Black Ribbon Day (European Union and other countries), and related observances:
- Liberation from Fascist Occupation Day (Romania)
- International Day for the Remembrance of the Slave Trade and its Abolition
- Umhlanga Day (Eswatini)
- August 24
- Flag Day (Liberia)
- Independence Day of Ukraine
- International Strange Music Day
- National Waffle Day (United States)
- Nostalgia Night (Uruguay)
- Willka Raymi (Cusco, Peru)
- August 25
- Day of Songun (North Korea)
- Independence Day (Uruguay)
- Liberation Day (France)
- National Banana Split Day (United States)
- National Whiskey Sour Day (United States)
- Soldier\'s Day (Brazil)
- August 26
- Herero Day (Namibia)
- Heroes\' Day (Namibia)
- Repentance Day (Papua New Guinea)
- Women\'s Equality Day (United States)
- August 27
- Film and Movies Day (Russia)
- Independence Day of the Republic of Moldova
- Lyndon Baines Johnson Day (Texas, United States)
- National Banana Lovers Day (United States)
- National Pots De Creme Day (United States)
- August 28
- Assumption of Mary (Eastern Orthodox Church (Public holiday in North Macedonia, Serbia, and Georgia (country))
- Crackers of the Keyboard Day
- National Cherry Turnover Day (United States)
- August 29
- International Day against Nuclear Tests
- Miners\' Day (Ukraine)
- More Herbs, Less Salt Day
- National Lemon Juice Day (United States)
- National Chop Suey Day (United States)
- National Sports Day (India)
- Slovak National Uprising Anniversary (Slovakia)
- Telugu Language Day (India)
- August 30
- Constitution Day (Kazakhstan)
- Constitution Day (Turks and Caicos Islands)
- Independence Day (Tatarstan, Russia, unrecognized)
- International Day of the Disappeared (International)
- Popular Consultation Day (East Timor)
- Saint Rose of Lima\'s Day (Peru)
- Victory Day (Turkey)
- August 31
- Baloch-Pakhtun Unity Day (Balochs and Pashtuns, International observance)
- Day of Solidarity and Freedom (Poland)
- Independence Day (Federation of Malaya, Malaysia)
- Independence Day (Kyrgyzstan)
- Independence Day (Trinidad and Tobago)
- National Trail Mix Day (United States)
- North Borneo Self-government Day (Sabah, Borneo)
- Romanian Language Day (Romania, Moldova)
| 2025-08-01T00:00:00 |
1,009 |
April 12
| 2025-08-01T00:00:00 |
|
1,011 |
April 30
| 2025-08-01T00:00:00 |
|
1,013 |
August 27
| 2025-08-01T00:00:00 |
|
1,027 |
August 9
| 2025-08-01T00:00:00 |
|
1,036 |
Aalborg Municipality
|
**Ålborg Municipality** (*Ålborg Kommune*) is a municipality in North Jutland Region on the Jutland peninsula in northern Denmark. The municipality straddles the Limfjord, the waterway which connects the North Sea and the Kattegat east-to-west, and which separates the main body of the Jutland peninsula from the island of Vendsyssel-Thy north-to-south. It has a land area of 1,143.99 km2 and a population of 224,612 (1. January 2025).
It is also the name of the municipality\'s main city Aalborg and the site of its municipal council, as well as the name of a seaport.
The municipality and the town have chosen to retain the traditional spelling of the name as *Aalborg*, although the new spelling *Ålborg* is used in other contexts, such as Ålborg Bight (*Ålborg Bugt*), the body of water which lies to the east of the Jutland peninsula.
## Municipal reform of 2007 {#municipal_reform_of_2007}
As of 1 January 2007 Aalborg municipality joined with the municipalities of Hals, Nibe, and Sejlflod to form a new Aalborg municipality. The former Aalborg municipality, including the island of Egholm, covered an area of 560 km2, with a total population of 192,353 (2005). Its last mayor was Henning G. Jensen, a member of the Social Democrats (**Socialdemokraterne**) political party. The former municipality was bordered by Sejlflod and Hals to the east, Dronninglund and Brønderslev to the north, Aabybro and Nibe to the west, and Støvring and Skørping to the south. It belonged to North Jutland County.
## Geography
### Surroundings
The waters in the Limfjord splitting the municipality are called Langerak to the east and *Gjøl Bredning* to the west. The island of Egholm is located in *Gjøl Bredning*, and is connected by ferry to the city of Aalborg at its southern shore.
The area is typical for the north of Jutland. To the west, the Limfjord broadens into an irregular lake (salt water), with low, marshy shores and many islands. Northwest is Store Vildmose (\"Greater Wild bog\"), a swamp where a mirage is sometimes seen in summer. Southeast lies the similar Lille Vildmose (\"Lesser Wild bog\"). Store Vildmose was drained and farmed in the beginning of the 20th century, and Lille Vildmose is now the largest moor in Denmark.
### Urban areas in Aalborg Municipality {#urban_areas_in_aalborg_municipality}
Aalborg City has a total population of 123,432. The metropolitan area is a conurbation of the Aalborg urban area in Himmerland (102,312) and the *italic=no* urban area in *italic=no* (21,120).
Nr Urban area Population (2011)
---- ------------ -------------------
1 Aalborg 103,545
2 21,376
3 Svenstrup 6,751
4 Nibe 4,987
5 Vodskov 4,399
6 Klarup 4,182
7 Gistrup 3,573
8 Storvorde 3,243
9 Vestbjerg 2,677
10 Frejlev 2,579
: The largest urban areas in Aalborg Municipality
## Economy
North Flying has its head office on the property of Aalborg Airport in *italic=no*, Aalborg Municipality.
## Politics
### Municipal council {#municipal_council}
Aalborg\'s municipal council consists of 31 members, elected every four years.
Below are the municipal councils elected since the Municipal Reform of 2007.
Election Party
------------------------------------------ ------------------------------------------ ------------------------------------------ ------------------------------------------ ------------------------------------------
**`{{font color|white|A}}`{=mediawiki}** **`{{font color|white|B}}`{=mediawiki}** **`{{font color|white|C}}`{=mediawiki}** **`{{font color|white|F}}`{=mediawiki}** **`{{font color|white|I}}`{=mediawiki}**
2005 15 2 3 2
2009 12 1 2 5
2013 12 2 1 1
2017 17 1 1
## Twin towns -- sister cities {#twin_towns_sister_cities}
Aalborg is twinned with 34 cities, more than any other city in Denmark. Every four years, Aalborg gathers young people from most of its twin towns for a week of sports, known as Ungdomslegene (Youth Games). `{{div col|colwidth=20em}}`{=mediawiki}
- *italic=no*, Netherlands
- Antibes, France
- Büdelsdorf, Germany
- Edinburgh, Scotland, United Kingdom
- Fredrikstad, Norway
- Fuglafjørður, Faroe Islands
- Galway, Ireland
- Gdynia, Poland
- Haifa, Israel
- Hefei, China
- *italic=no*, Austria
- , Greenland
- Karlskoga, Sweden
- Lancaster, England
- Lerum, Sweden
- Liperi, Finland
- *italic=no*, Iceland
- Orsa, Sweden
- Orust, Sweden
- Ośno Lubuskie, Poland
- *italic=no*, Russia
- Racine, United States
- Rapperswil-Jona, Switzerland
- Rendalen, Norway
- Rendsburg, Germany
- Riga, Latvia
- Riihimäki, Finland
- *italic=no*, Greenland
- Solvang, United States
- *italic=no*, Romania
- *italic=no*, Bulgaria
- Vilnius, Lithuania
- *italic=no*, Germany
| 2025-08-01T00:00:00 |
1,043 |
Northern cavefish
|
The **northern cavefish** or **northern blindfish** (***Amblyopsis spelaea***) is found in caves through Kentucky and southern Indiana. The International Union for Conservation of Nature lists the species as near threatened.
The life cycle of northern cavefish includes a protolarval stage. In this stage, eggs and those that have recently hatched into protolarvae are kept by the mother internally in a gill chamber. Juveniles become free swimming and can leave. The northern cavefish lives to a maximum age of at least ten years and reaches sexual maturity at approximately six years of age. Some estimates suggest that speciments may live up to 30-40 years in environments with stable food supplies.
During a 2013 study of *Amblyopsis spelaea*, scientists found that the species was divided into two distinct evolutionary lineages: one north of the Ohio River, in Indiana, and one south of the river, in Kentucky. The southern population retained the name *A. spelaea* and the northern was re-designated *Amblyopsis hoosieri* in a 2014 paper published in the journal *ZooKeys*. Neither species is found north of the White River, flowing east to west south of Bedford, Indiana.
The northern cavefish was under consideration for listing under the Endangered Species Act, however, the U.S. Fish and Wildlife Service found in 2023 that despite the loss of two metapopulations of *A. spelaea*, listing was not warranted, as the four metapopulations that still exist had sufficient redundancy of subpopulations to mitigate threats. The metapopulations are divided among two units that are separated by the Rough Creek Fault Zone. Threats to the species include habitat degradation, especially by groundwater contamination from encroaching agricultural operations, cities and industry, forest loss and surface water impoundment.
| 2025-08-01T00:00:00 |
1,049 |
Amateur
|
An **amateur** (`{{ety|fr||one who loves}}`{=mediawiki}) is generally considered a person who pursues an avocation independent from their source of income. Amateurs and their pursuits are also described as popular, informal, self-taught, user-generated, DIY, and hobbyist.
## History
Historically, the amateur was considered to be the ideal balance between pure intent, open mind, and the interest or passion for a subject. That ideology spanned many different fields of interest. It may have its roots in the ancient Greek philosophy of amateur athletes competing in the Olympics. The ancient Greek citizens spent most of their time in other pursuits, but competed according to their natural talents and abilities.
The \"gentleman amateur\" was a phenomenon among the gentry of Great Britain from the 17th century until the 20th century. With the start of the Age of Reason, with people thinking more about how the world works around them, (see science in the Age of Enlightenment), things like the cabinets of curiosities, and the writing of the book *The Christian Virtuoso*, started to shape the idea of the gentleman amateur. He was vastly interested in a particular topic, and studied, observed, and collected things and information on his topic of choice. The Royal Society in Great Britain was generally composed of these \"gentleman amateurs\", and is one of the reasons science today exists the way it does. A few examples of these gentleman amateurs are Francis Bacon, Isaac Newton, and Sir Robert Cotton, 1st Baronet, of Connington.
Amateurism can be seen in both a negative and positive light. Since amateurs often lack formal training and are self-taught, some amateur work may be considered sub-par. For example, amateur athletes in sports such as basketball, baseball, or football are regarded as possessing a lower level of ability than professional athletes. On the other hand, an amateur may be in a position to approach a subject with an open mind (as a result of the lack of formal training) and in a financially disinterested manner. An amateur who dabbles in a field out of interest rather than as a profession, or possesses a general but superficial interest in any art or a branch of knowledge, is often referred to as a dilettante.
## Amateur athletics {#amateur_athletics}
## Olympics
Through most of the 20th century the Olympics allowed only amateur athletes to participate and this amateur code was strictly enforced, Jim Thorpe was stripped of track and field medals for having taken expense money for playing baseball in 1912.
Later on, the nations of the Communist Bloc entered teams of Olympians who were all nominally students, soldiers, or working in a profession, but many of whom were in reality paid by the state to train on a full-time basis.
Near the end of the 1960s, the Canadian Amateur Hockey Association (CAHA) felt their amateur players could no longer be competitive against the Soviet team\'s full-time athletes and the other constantly improving European teams. They pushed for the ability to use players from professional leagues but met opposition from the International Ice Hockey Federation (IIHF) and the International Olympic Committee (IOC). At the IIHF Congress in 1969, the IIHF decided to allow Canada to use nine non-NHL professional hockey players at the 1970 World Championships in Montreal and Winnipeg, Manitoba, Canada. The decision was reversed in January 1970 after IOC President Avery Brundage said that ice hockey\'s status as an Olympic sport would be in jeopardy if the change was made. In response, Canada withdrew from all international ice hockey competitions and officials stated that they would not return until \"open competition\" was instituted. Günther Sabetzki became president of the IIHF in 1975 and helped to resolve the dispute with the CAHA. In 1976, the IIHF agreed to allow \"open competition\" between all players in the World Championships. However, NHL players were still not allowed to play in the Olympics, because of the unwillingness of the NHL to take a break mid-season and the IOC\'s amateur-only policy.
Before the 1984 Winter Olympics, a dispute formed over what made a player a professional. The IOC had adopted a rule that made any player who had signed an NHL contract but played less than ten games in the league eligible. However, the United States Olympic Committee maintained that any player contracted with an NHL team was a professional and therefore not eligible to play. The IOC held an emergency meeting that ruled NHL-contracted players were eligible, as long as they had not played in any NHL games. This made five players on Olympic rosters---one Austrian, two Italians and two Canadians---ineligible. Players who had played in other professional leagues---such as the World Hockey Association---were allowed to play. Canadian hockey official Alan Eagleson stated that the rule was only applied to the NHL and that professionally contracted players in European leagues were still considered amateurs. Murray Costello of the CAHA suggested that a Canadian withdrawal was possible. In 1986, the IOC voted to allow all athletes to compete in Olympic Games starting in 1988, but let the individual sport federations decide if they wanted to allow professionals.
After the 1972 retirement of IOC President Brundage, the Olympic amateurism rules were steadily relaxed, amounting only to technicalities and lip service, until being completely abandoned in the 1990s (in the United States, the Amateur Sports Act of 1978 prohibits national governing bodies from having more stringent standards of amateur status than required by international governing bodies of respective sports. The act caused the breakup of the Amateur Athletic Union as a wholesale sports governing body at the Olympic level).
Olympic regulations regarding amateur status of athletes were eventually abandoned in the 1990s with the exception of wrestling, where the amateur fight rules are used because professional wrestling is largely staged with predetermined outcomes. Starting from the 2016 Summer Olympics, professionals were allowed to compete in boxing, though amateur fight rules are still used for the tournament.
## Contribution of amateurs {#contribution_of_amateurs}
Many amateurs make valuable contributions in the field of computer programming through the open source movement. Amateur dramatics is the performance of plays or musical theater, often to high standards, but lacking the budgets of professional West End or Broadway performances. Astronomy, chemistry, history, linguistics, and the natural sciences are among the fields that have benefited from the activities of amateurs. Gregor Mendel was an amateur scientist who never held a position in his field of study. Radio astronomy was founded by Grote Reber, an amateur radio operator. Radio itself was greatly advanced by Guglielmo Marconi, a young Italian man who started out by tinkering with a coherer and a spark coil as an amateur electrician. Pierre de Fermat was a highly influential mathematician whose primary vocation was law.
In the 2000s and 2010s, the distinction between amateur and professional has become increasingly blurred, especially in areas such as computer programming, music and astronomy. The term amateur professionalism, or pro-am, is used to describe these activities.
## List of amateur pursuits {#list_of_amateur_pursuits}
- Amateur astronomy, including a list of notable amateur astronomers
- Amateur chemistry, including a list of notable amateur chemists
- Amateur film
- Amateur geology or rockhounding, including a list of notable amateur geologists
- Amateur journalism
- Amateur radio
- Amateur sports
- Amateur theatre
- Amateur pornography
- Arts and crafts or handicraft, including a list of handicrafts carried out by amateurs
- Fan fiction
- Fan art
- Independent scholar
- Independent scientist or gentleman scientist, including a list of notable amateur scientists
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1,063 |
Algorithms for calculating variance
|
**Algorithms for calculating variance** play a major role in computational statistics. A key difficulty in the design of good algorithms for this problem is that formulas for the variance may involve sums of squares, which can lead to numerical instability as well as to arithmetic overflow when dealing with large values.
## Naïve algorithm {#naïve_algorithm}
A formula for calculating the variance of an entire population of size *N* is:
$$\sigma^2 = \overline{(x^2)} - \bar x^2 = \frac{\sum_{i=1}^N x_i^2}{N} - \left(\frac{\sum_{i=1}^N x_i}{N}\right)^2$$
Using Bessel\'s correction to calculate an unbiased estimate of the population variance from a finite sample of *n* observations, the formula is:
$$s^2 = \left(\frac {\sum_{i=1}^n x_i^2} n - \left( \frac {\sum_{i=1}^n x_i} n \right)^2\right) \cdot \frac {n}{n-1}.$$
Therefore, a naïve algorithm to calculate the estimated variance is given by the following:
- Let `{{math|''n'' ← 0, Sum ← 0, SumSq ← 0}}`{=mediawiki}
- For each datum `{{mvar|x}}`{=mediawiki}:
-
-
-
- (SumSq − (Sum × Sum) / n) / (n − 1)}}
This algorithm can easily be adapted to compute the variance of a finite population: simply divide by *n* instead of *n* − 1 on the last line.
Because `{{math|SumSq}}`{=mediawiki} and `{{math|(Sum×Sum)/''n''}}`{=mediawiki} can be very similar numbers, cancellation can lead to the precision of the result to be much less than the inherent precision of the floating-point arithmetic used to perform the computation. Thus this algorithm should not be used in practice, and several alternate, numerically stable, algorithms have been proposed. This is particularly bad if the standard deviation is small relative to the mean.
### Computing shifted data {#computing_shifted_data}
The variance is invariant with respect to changes in a location parameter, a property which can be used to avoid the catastrophic cancellation in this formula.
$$\operatorname{Var}(X-K)=\operatorname{Var}(X).$$
with $K$ any constant, which leads to the new formula
$$\sigma^2 = \frac {\sum_{i=1}^n (x_i-K)^2 - (\sum_{i=1}^n (x_i-K))^2/n}{n-1}.$$
the closer $K$ is to the mean value the more accurate the result will be, but just choosing a value inside the samples range will guarantee the desired stability. If the values $(x_i - K)$ are small then there are no problems with the sum of its squares, on the contrary, if they are large it necessarily means that the variance is large as well. In any case the second term in the formula is always smaller than the first one therefore no cancellation may occur.
If just the first sample is taken as $K$ the algorithm can be written in Python programming language as
``` python
def shifted_data_variance(data):
if len(data) < 2:
return 0.0
K = data[0]
n = Ex = Ex2 = 0.0
for x in data:
n += 1
Ex += x - K
Ex2 += (x - K) ** 2
variance = (Ex2 - Ex**2 / n) / (n - 1)
# use n instead of (n-1) if want to compute the exact variance of the given data
# use (n-1) if data are samples of a larger population
return variance
```
This formula also facilitates the incremental computation that can be expressed as
``` python
K = Ex = Ex2 = 0.0
n = 0
def add_variable(x):
global K, n, Ex, Ex2
if n == 0:
K = x
n += 1
Ex += x - K
Ex2 += (x - K) ** 2
def remove_variable(x):
global K, n, Ex, Ex2
n -= 1
Ex -= x - K
Ex2 -= (x - K) ** 2
def get_mean():
global K, n, Ex
return K + Ex / n
def get_variance():
global n, Ex, Ex2
return (Ex2 - Ex**2 / n) / (n - 1)
```
## Two-pass algorithm {#two_pass_algorithm}
An alternative approach, using a different formula for the variance, first computes the sample mean,
$$\bar x = \frac {\sum_{j=1}^n x_j} n,$$ and then computes the sum of the squares of the differences from the mean,
$$\text{sample variance} = s^2 = \dfrac {\sum_{i=1}^n (x_i - \bar x)^2}{n-1},$$ where *s* is the standard deviation. This is given by the following code:
``` python
def two_pass_variance(data):
n = len(data)
mean = sum(data) / n
variance = sum((x - mean) ** 2 for x in data) / (n - 1)
return variance
```
This algorithm is numerically stable if *n* is small. However, the results of both of these simple algorithms (\"naïve\" and \"two-pass\") can depend inordinately on the ordering of the data and can give poor results for very large data sets due to repeated roundoff error in the accumulation of the sums. Techniques such as compensated summation can be used to combat this error to a degree.
## Welford\'s online algorithm {#welfords_online_algorithm}
It is often useful to be able to compute the variance in a single pass, inspecting each value $x_i$ only once; for example, when the data is being collected without enough storage to keep all the values, or when costs of memory access dominate those of computation. For such an online algorithm, a recurrence relation is required between quantities from which the required statistics can be calculated in a numerically stable fashion.
The following formulas can be used to update the mean and (estimated) variance of the sequence, for an additional element *x*~*n*~. Here, $\overline{x}_n = \frac{1}{n} \sum_{i=1}^n x_i$ denotes the sample mean of the first *n* samples $(x_1,\dots,x_n)$, $\sigma^2_n = \frac{1}{n} \sum_{i=1}^n \left(x_i - \overline{x}_n \right)^2$ their biased sample variance, and $s^2_n = \frac{1}{n - 1} \sum_{i=1}^n \left(x_i - \overline{x}_n \right)^2$ their unbiased sample variance.
$$\bar x_n = \frac{(n-1) \, \bar x_{n-1} + x_n}{n} = \bar x_{n-1} + \frac{x_n - \bar x_{n-1}}{n}$$
$$\sigma^2_n = \frac{(n-1) \, \sigma^2_{n-1} + (x_n - \bar x_{n-1})(x_n - \bar x_n)}{n} = \sigma^2_{n-1} + \frac{(x_n - \bar x_{n-1})(x_n - \bar x_n) - \sigma^2_{n-1}}{n}.$$
$$s^2_n = \frac{n-2}{n-1} \, s^2_{n-1} + \frac{(x_n - \bar x_{n-1})^2}{n} = s^2_{n-1} + \frac{(x_n - \bar x_{n-1})^2}{n} - \frac{s^2_{n-1}}{n-1}, \quad n>1$$
These formulas suffer from numerical instability , as they repeatedly subtract a small number from a big number which scales with *n*. A better quantity for updating is the sum of squares of differences from the current mean, $\sum_{i=1}^n (x_i - \bar x_n)^2$, here denoted $M_{2,n}$:
: \\begin{align}
M\_{2,n} & = M\_{2,n-1} + (x_n - \\bar x\_{n-1})(x_n - \\bar x_n) \\\\\[4pt\] \\sigma\^2_n & = \\frac{M\_{2,n}}{n} \\\\\[4pt\] s\^2_n & = \\frac{M\_{2,n}}{n-1} \\end{align}
This algorithm was found by Welford, and it has been thoroughly analyzed. It is also common to denote $M_k = \bar x_k$ and $S_k = M_{2,k}$.
An example Python implementation for Welford\'s algorithm is given below.
``` python
# For a new value new_value, compute the new count, new mean, the new M2.
# mean accumulates the mean of the entire dataset
# M2 aggregates the squared distance from the mean
# count aggregates the number of samples seen so far
def update(existing_aggregate, new_value):
(count, mean, M2) = existing_aggregate
count += 1
delta = new_value - mean
mean += delta / count
delta2 = new_value - mean
M2 += delta * delta2
return (count, mean, M2)
# Retrieve the mean, variance and sample variance from an aggregate
def finalize(existing_aggregate):
(count, mean, M2) = existing_aggregate
if count < 2:
return float("nan")
else:
(mean, variance, sample_variance) = (mean, M2 / count, M2 / (count - 1))
return (mean, variance, sample_variance)
```
This algorithm is much less prone to loss of precision due to catastrophic cancellation, but might not be as efficient because of the division operation inside the loop. For a particularly robust two-pass algorithm for computing the variance, one can first compute and subtract an estimate of the mean, and then use this algorithm on the residuals.
The parallel algorithm below illustrates how to merge multiple sets of statistics calculated online.
## Weighted incremental algorithm {#weighted_incremental_algorithm}
The algorithm can be extended to handle unequal sample weights, replacing the simple counter *n* with the sum of weights seen so far. West (1979) suggests this incremental algorithm:
``` python
def weighted_incremental_variance(data_weight_pairs):
w_sum = w_sum2 = mean = S = 0
for x, w in data_weight_pairs:
w_sum = w_sum + w
w_sum2 = w_sum2 + w**2
mean_old = mean
mean = mean_old + (w / w_sum) * (x - mean_old)
S = S + w * (x - mean_old) * (x - mean)
population_variance = S / w_sum
# Bessel's correction for weighted samples
# Frequency weights
sample_frequency_variance = S / (w_sum - 1)
# Reliability weights
sample_reliability_variance = S / (1 - w_sum2 / (w_sum**2))
```
## Parallel algorithm {#parallel_algorithm}
Chan et al. note that Welford\'s online algorithm detailed above is a special case of an algorithm that works for combining arbitrary sets $A$ and $B$:
$$\begin{align}
n_{AB} & = n_A + n_B \\
\delta & = \bar x_B - \bar x_A \\
\bar x_{AB} & = \bar x_A + \delta\cdot\frac{n_B}{n_{AB}} \\
M_{2,AB} & = M_{2,A} + M_{2,B} + \delta^2\cdot\frac{n_A n_B}{n_{AB}} \\
\end{align}$$. This may be useful when, for example, multiple processing units may be assigned to discrete parts of the input.
Chan\'s method for estimating the mean is numerically unstable when $n_A \approx n_B$ and both are large, because the numerical error in $\delta = \bar x_B - \bar x_A$ is not scaled down in the way that it is in the $n_B = 1$ case. In such cases, prefer $\bar x_{AB} = \frac{n_A \bar x_A + n_B \bar x_B}{n_{AB}}$.
``` python
def parallel_variance(n_a, avg_a, M2_a, n_b, avg_b, M2_b):
n = n_a + n_b
delta = avg_b - avg_a
M2 = M2_a + M2_b + delta**2 * n_a * n_b / n
var_ab = M2 / (n - 1)
return var_ab
```
This can be generalized to allow parallelization with AVX, with GPUs, and computer clusters, and to covariance.
## Example
Assume that all floating point operations use standard IEEE 754 double-precision`{{Broken anchor|date=2025-06-11|bot=User:Cewbot/log/20201008/configuration|target_link=IEEE 754#Double-precision 64 bit|reason= }}`{=mediawiki} arithmetic. Consider the sample (4, 7, 13, 16) from an infinite population. Based on this sample, the estimated population mean is 10, and the unbiased estimate of population variance is 30. Both the naïve algorithm and two-pass algorithm compute these values correctly.
Next consider the sample (`{{nowrap|10<sup>8</sup> + 4}}`{=mediawiki}, `{{nowrap|10<sup>8</sup> + 7}}`{=mediawiki}, `{{nowrap|10<sup>8</sup> + 13}}`{=mediawiki}, `{{nowrap|10<sup>8</sup> + 16}}`{=mediawiki}), which gives rise to the same estimated variance as the first sample. The two-pass algorithm computes this variance estimate correctly, but the naïve algorithm returns 29.333333333333332 instead of 30.
While this loss of precision may be tolerable and viewed as a minor flaw of the naïve algorithm, further increasing the offset makes the error catastrophic. Consider the sample (`{{nowrap|10<sup>9</sup> + 4}}`{=mediawiki}, `{{nowrap|10<sup>9</sup> + 7}}`{=mediawiki}, `{{nowrap|10<sup>9</sup> + 13}}`{=mediawiki}, `{{nowrap|10<sup>9</sup> + 16}}`{=mediawiki}). Again the estimated population variance of 30 is computed correctly by the two-pass algorithm, but the naïve algorithm now computes it as −170.66666666666666. This is a serious problem with naïve algorithm and is due to catastrophic cancellation in the subtraction of two similar numbers at the final stage of the algorithm.
## Higher-order statistics {#higher_order_statistics}
Terriberry extends Chan\'s formulae to calculating the third and fourth central moments, needed for example when estimating skewness and kurtosis:
$$\begin{align}
M_{3,X} = M_{3,A} + M_{3,B} & {} + \delta^3\frac{n_A n_B (n_A - n_B)}{n_X^2} + 3\delta\frac{n_AM_{2,B} - n_BM_{2,A}}{n_X} \\[6pt]
M_{4,X} = M_{4,A} + M_{4,B} & {} + \delta^4\frac{n_A n_B \left(n_A^2 - n_A n_B + n_B^2\right)}{n_X^3} \\[6pt]
& {} + 6\delta^2\frac{n_A^2 M_{2,B} + n_B^2 M_{2,A}}{n_X^2} + 4\delta\frac{n_AM_{3,B} - n_BM_{3,A}}{n_X}
\end{align}$$
Here the $M_k$ are again the sums of powers of differences from the mean $\sum(x - \overline{x})^k$, giving
:
\\begin{align} & \\text{skewness} = g_1 = \\frac{\\sqrt{n} M_3}{M_2\^{3/2}}, \\\\\[4pt\] & \\text{kurtosis} = g_2 = \\frac{n M_4}{M_2\^2}-3. \\end{align}
For the incremental case (i.e., $B = \{x\}$), this simplifies to:
:
\\begin{align} \\delta & = x - m \\\\\[5pt\] m\' & = m + \\frac{\\delta}{n} \\\\\[5pt\] M_2\' & = M_2 + \\delta\^2 \\frac{n-1}{n} \\\\\[5pt\] M_3\' & = M_3 + \\delta\^3 \\frac{ (n - 1) (n - 2)}{n\^2} - \\frac{3\\delta M_2}{n} \\\\\[5pt\] M_4\' & = M_4 + \\frac{\\delta\^4 (n - 1) (n\^2 - 3n + 3)}{n\^3} + \\frac{6\\delta\^2 M_2}{n\^2} - \\frac{4\\delta M_3}{n} \\end{align}
By preserving the value $\delta / n$, only one division operation is needed and the higher-order statistics can thus be calculated for little incremental cost.
An example of the online algorithm for kurtosis implemented as described is:
``` python
def online_kurtosis(data):
n = mean = M2 = M3 = M4 = 0
for x in data:
n1 = n
n = n + 1
delta = x - mean
delta_n = delta / n
delta_n2 = delta_n**2
term1 = delta * delta_n * n1
mean = mean + delta_n
M4 = M4 + term1 * delta_n2 * (n**2 - 3*n + 3) + 6 * delta_n2 * M2 - 4 * delta_n * M3
M3 = M3 + term1 * delta_n * (n - 2) - 3 * delta_n * M2
M2 = M2 + term1
# Note, you may also calculate variance using M2, and skewness using M3
# Caution: If all the inputs are the same, M2 will be 0, resulting in a division by 0.
kurtosis = (n * M4) / (M2**2) - 3
return kurtosis
```
Pébaÿ further extends these results to arbitrary-order central moments, for the incremental and the pairwise cases, and subsequently Pébaÿ et al. for weighted and compound moments. One can also find there similar formulas for covariance.
Choi and Sweetman offer two alternative methods to compute the skewness and kurtosis, each of which can save substantial computer memory requirements and CPU time in certain applications. The first approach is to compute the statistical moments by separating the data into bins and then computing the moments from the geometry of the resulting histogram, which effectively becomes a one-pass algorithm for higher moments. One benefit is that the statistical moment calculations can be carried out to arbitrary accuracy such that the computations can be tuned to the precision of, e.g., the data storage format or the original measurement hardware. A relative histogram of a random variable can be constructed in the conventional way: the range of potential values is divided into bins and the number of occurrences within each bin are counted and plotted such that the area of each rectangle equals the portion of the sample values within that bin:
: $H(x_k)=\frac{h(x_k)}{A}$
where $h(x_k)$ and $H(x_k)$ represent the frequency and the relative frequency at bin $x_k$ and $A= \sum_{k=1}^K h(x_k) \,\Delta x_k$ is the total area of the histogram. After this normalization, the $n$ raw moments and central moments of $x(t)$ can be calculated from the relative histogram:
:
`m_n^{(h)} = \sum_{k=1}^{K} x_k^n H(x_k) \, \Delta x_k`\
` = \frac{1}{A} \sum_{k=1}^K x_k^n h(x_k) \, \Delta x_k`
:
`\theta_n^{(h)}= \sum_{k=1}^{K} \Big(x_k-m_1^{(h)}\Big)^n \, H(x_k) \, \Delta x_k`\
` = \frac{1}{A} \sum_{k=1}^{K} \Big(x_k-m_1^{(h)}\Big)^n h(x_k) \, \Delta x_k`
where the superscript $^{(h)}$ indicates the moments are calculated from the histogram. For constant bin width $\Delta x_k=\Delta x$ these two expressions can be simplified using $I= A/\Delta x$:
:
`m_n^{(h)}= \frac{1}{I} \sum_{k=1}^K x_k^n \, h(x_k)`
:
`\theta_n^{(h)}= \frac{1}{I} \sum_{k=1}^K \Big(x_k-m_1^{(h)}\Big)^n h(x_k)`
The second approach from Choi and Sweetman is an analytical methodology to combine statistical moments from individual segments of a time-history such that the resulting overall moments are those of the complete time-history. This methodology could be used for parallel computation of statistical moments with subsequent combination of those moments, or for combination of statistical moments computed at sequential times.
If $Q$ sets of statistical moments are known: $(\gamma_{0,q},\mu_{q},\sigma^2_{q},\alpha_{3,q},\alpha_{4,q})
\quad$ for $q=1,2,\ldots,Q$, then each $\gamma_n$ can be expressed in terms of the equivalent $n$ raw moments:
:
\\gamma\_{n,q}= m\_{n,q} \\gamma\_{0,q} \\qquad \\quad \\textrm{for} \\quad n=1,2,3,4 \\quad \\text{ and } \\quad q = 1,2, \\dots ,Q
where $\gamma_{0,q}$ is generally taken to be the duration of the $q^{th}$ time-history, or the number of points if $\Delta t$ is constant.
The benefit of expressing the statistical moments in terms of $\gamma$ is that the $Q$ sets can be combined by addition, and there is no upper limit on the value of $Q$.
:
`\gamma_{n,c}= \sum_{q=1}^Q \gamma_{n,q} \quad \quad \text{for } n=0,1,2,3,4`
where the subscript $_c$ represents the concatenated time-history or combined $\gamma$. These combined values of $\gamma$ can then be inversely transformed into raw moments representing the complete concatenated time-history
:
`m_{n,c}=\frac{\gamma_{n,c}}{\gamma_{0,c}} \quad \text{for } n=1,2,3,4`
Known relationships between the raw moments ($m_n$) and the central moments ($\theta_n = \operatorname E[(x-\mu)^n])$) are then used to compute the central moments of the concatenated time-history. Finally, the statistical moments of the concatenated history are computed from the central moments:
:
`\mu_c=m_{1,c}`\
`\qquad \sigma^2_c=\theta_{2,c}`\
`\qquad \alpha_{3,c}=\frac{\theta_{3,c}}{\sigma_c^3}`\
`\qquad \alpha_{4,c}={\frac{\theta_{4,c}}{\sigma_c^4}}-3`
## Covariance
Very similar algorithms can be used to compute the covariance.
### Naïve algorithm {#naïve_algorithm_1}
The naïve algorithm is
$$\operatorname{Cov}(X,Y) = \frac {\sum_{i=1}^n x_i y_i - (\sum_{i=1}^n x_i)(\sum_{i=1}^n y_i)/n}{n}.$$
For the algorithm above, one could use the following Python code:
``` python
def naive_covariance(data1, data2):
n = len(data1)
sum1 = sum(data1)
sum2 = sum(data2)
sum12 = sum([i1 * i2 for i1, i2 in zip(data1, data2)])
covariance = (sum12 - sum1 * sum2 / n) / n
return covariance
```
### With estimate of the mean {#with_estimate_of_the_mean}
As for the variance, the covariance of two random variables is also shift-invariant, so given any two constant values $k_x$ and $k_y,$ it can be written:
$$\operatorname{Cov}(X,Y) = \operatorname{Cov}(X-k_x,Y-k_y) = \dfrac {\sum_{i=1}^n (x_i-k_x) (y_i-k_y) - (\sum_{i=1}^n (x_i-k_x))(\sum_{i=1}^n (y_i-k_y))/n}{n}.$$
and again choosing a value inside the range of values will stabilize the formula against catastrophic cancellation as well as make it more robust against big sums. Taking the first value of each data set, the algorithm can be written as:
``` python
def shifted_data_covariance(data_x, data_y):
n = len(data_x)
if n < 2:
return 0
kx = data_x[0]
ky = data_y[0]
Ex = Ey = Exy = 0
for ix, iy in zip(data_x, data_y):
Ex += ix - kx
Ey += iy - ky
Exy += (ix - kx) * (iy - ky)
return (Exy - Ex * Ey / n) / n
```
### Two-pass {#two_pass}
The two-pass algorithm first computes the sample means, and then the covariance:
$$\bar x = \sum_{i=1}^n x_i/n$$
$$\bar y = \sum_{i=1}^n y_i/n$$
$$\operatorname{Cov}(X,Y) = \frac {\sum_{i=1}^n (x_i - \bar x)(y_i - \bar y)}{n}.$$
The two-pass algorithm may be written as:
``` python
def two_pass_covariance(data1, data2):
n = len(data1)
mean1 = sum(data1) / n
mean2 = sum(data2) / n
covariance = 0
for i1, i2 in zip(data1, data2):
a = i1 - mean1
b = i2 - mean2
covariance += a * b / n
return covariance
```
A slightly more accurate compensated version performs the full naive algorithm on the residuals. The final sums $\sum_i x_i$ and $\sum_i y_i$ *should* be zero, but the second pass compensates for any small error.
### Online
A stable one-pass algorithm exists, similar to the online algorithm for computing the variance, that computes co-moment $C_n = \sum_{i=1}^n (x_i - \bar x_n)(y_i - \bar y_n)$:
$$\begin{alignat}{2}
\bar x_n &= \bar x_{n-1} &\,+\,& \frac{x_n - \bar x_{n-1}}{n} \\[5pt]
\bar y_n &= \bar y_{n-1} &\,+\,& \frac{y_n - \bar y_{n-1}}{n} \\[5pt]
C_n &= C_{n-1} &\,+\,& (x_n - \bar x_n)(y_n - \bar y_{n-1}) \\[5pt]
&= C_{n-1} &\,+\,& (x_n - \bar x_{n-1})(y_n - \bar y_n)
\end{alignat}$$ The apparent asymmetry in that last equation is due to the fact that $(x_n - \bar x_n) = \frac{n-1}{n}(x_n - \bar x_{n-1})$, so both update terms are equal to $\frac{n-1}{n}(x_n - \bar x_{n-1})(y_n - \bar y_{n-1})$. Even greater accuracy can be achieved by first computing the means, then using the stable one-pass algorithm on the residuals.
Thus the covariance can be computed as
$$\begin{align}
\operatorname{Cov}_N(X,Y) = \frac{C_N}{N} &= \frac{\operatorname{Cov}_{N-1}(X,Y)\cdot(N-1) + (x_n - \bar x_n)(y_n - \bar y_{n-1})}{N}\\
&= \frac{\operatorname{Cov}_{N-1}(X,Y)\cdot(N-1) + (x_n - \bar x_{n-1})(y_n - \bar y_n)}{N}\\
&= \frac{\operatorname{Cov}_{N-1}(X,Y)\cdot(N-1) + \frac{N-1}{N}(x_n - \bar x_{n-1})(y_n - \bar y_{n-1})}{N}\\
&= \frac{\operatorname{Cov}_{N-1}(X,Y)\cdot(N-1) + \frac{N}{N-1}(x_n - \bar x_{n})(y_n - \bar y_{n})}{N}.
\end{align}$$
``` python
def online_covariance(data1, data2):
meanx = meany = C = n = 0
for x, y in zip(data1, data2):
n += 1
dx = x - meanx
meanx += dx / n
meany += (y - meany) / n
C += dx * (y - meany)
population_covar = C / n
# Bessel's correction for sample variance
sample_covar = C / (n - 1)
```
A small modification can also be made to compute the weighted covariance:
``` python
def online_weighted_covariance(data1, data2, data3):
meanx = meany = 0
wsum = wsum2 = 0
C = 0
for x, y, w in zip(data1, data2, data3):
wsum += w
wsum2 += w * w
dx = x - meanx
meanx += (w / wsum) * dx
meany += (w / wsum) * (y - meany)
C += w * dx * (y - meany)
population_covar = C / wsum
# Bessel's correction for sample variance
# Frequency weights
sample_frequency_covar = C / (wsum - 1)
# Reliability weights
sample_reliability_covar = C / (wsum - wsum2 / wsum)
```
Likewise, there is a formula for combining the covariances of two sets that can be used to parallelize the computation:
$$C_X = C_A + C_B + (\bar x_A - \bar x_B)(\bar y_A - \bar y_B)\cdot\frac{n_A n_B}{n_X}.$$
### Weighted batched version {#weighted_batched_version}
A version of the weighted online algorithm that does batched updated also exists: let $w_1, \dots w_N$ denote the weights, and write
$$\begin{alignat}{2}
\bar x_{n+k} &= \bar x_n &\,+\,& \frac{\sum_{i=n+1}^{n+k} w_i (x_i - \bar x_n)}{\sum_{i=1}^{n+k} w_i} \\
\bar y_{n+k} &= \bar y_n &\,+\,& \frac{\sum_{i=n+1}^{n+k} w_i (y_i - \bar y_n)}{\sum_{i=1}^{n+k} w_i} \\
C_{n+k} &= C_n &\,+\,& \sum_{i=n+1}^{n+k} w_i (x_i - \bar x_{n+k})(y_i - \bar y_n) \\
&= C_n &\,+\,& \sum_{i=n+1}^{n+k} w_i (x_i - \bar x_n)(y_i - \bar y_{n+k}) \\
\end{alignat}$$
The covariance can then be computed as
$$\operatorname{Cov}_N(X,Y) = \frac{C_N}{\sum_{i=1}^{N} w_i}$$
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1,070 |
Politics of Antigua and Barbuda
|
The **politics of Antigua and Barbuda** takes place in a framework of a unitary parliamentary representative democratic monarchy, wherein the sovereign of Antigua and Barbuda is the head of state, appointing a governor-general to act as vice-regal representative in the nation. A prime minister is appointed by the governor-general as the head of government, and of a multi-party system; the prime minister advises the governor-general on the appointment of a Council of Ministers. Executive power is exercised by the government. Legislative power is vested in both the government and the two chambers of the Parliament. The bicameral Parliament consists of the Senate (seventeen-member body appointed by the governor-general) and the House of Representatives (seventeen seats; members are elected by proportional representation to serve five-year terms).
Antigua and Barbuda has a long history of peaceful changes of government. Since the 1951 general election, the party system has been dominated by the Antigua and Barbuda Labour Party (ABLP), for a long time was dominated by the Bird family, particularly Prime Ministers Vere and Lester Bird. The opposition claimed to be disadvantaged by the ABLP\'s longstanding monopoly on patronage and its control of the media, especially in the 1999 general election. The opposition United Progressive Party (UPP) won the 2004 election, and its leader Winston Baldwin Spencer was prime minister of Antigua and Barbuda from 2004 to 2014.
The elections to the House of Representatives were held on 12 June 2014. The Antigua and Barbuda Labour Party government was elected with fourteen seats. The United Progressive Party had three seats in the House of Representatives. ABLP won 15 of the 17 seats in the 2018 snap election under the leadership of incumbent Prime Minister Gaston Browne.
Constitutional safeguards include freedom of speech, press, worship, movement, and association. Antigua and Barbuda is a member of the eastern Caribbean court system. The Judiciary is independent of the executive and the legislature. Jurisprudence is based on English common law.
## Executive branch {#executive_branch}
### Executive branch leadership {#executive_branch_leadership}
As head of state, King Charles III is represented in Antigua and Barbuda by a governor-general who acts on the advice of the prime minister and the cabinet.
## Legislative branch {#legislative_branch}
Antigua and Barbuda elects on national level a legislature. Parliament has two chambers. The House of Representatives has 19 members: 17 members elected for a five-year term in single-seat constituencies, and 2 ex officio members (president and speaker). The Senate has 17 appointed members. The prime minister is the leader of the majority party in the House and conducts affairs of state with the cabinet. The prime minister and the cabinet are responsible to the Parliament. Elections must be held at least every five years but may be called by the prime minister at any time.
There are special legislative provisions to account for Barbuda\'s low population relative to that of Antigua. Barbuda is guaranteed one member of the House of Representatives and two members of the Senate. In addition, there is a Barbuda Council to govern the internal affairs of the island.
## Political parties and elections {#political_parties_and_elections}
## Administrative divisions {#administrative_divisions}
The country is divided into six parishes, Saint George, John, Mary, Paul, Peter, and Phillip which are all on the island of Antigua. Additionally, the islands of Barbuda and Redonda are considered dependencies.
## Judicial branch {#judicial_branch}
Antigua and Barbuda is a member of the Eastern Caribbean Supreme Court. This court is headquartered in Saint Lucia, but at least one judge of the Supreme Court resides in Antigua and Barbuda, and presides over the High Court. The current High Court judges are Nicola Byer, Ann-Marie Smith, Jan Drysdale, Rene Williams, and Tunde Bakre as of September 2024.
Antigua is also a member of the Caribbean Court of Justice, although it has not yet acceded to Part III of the 2001 Agreement Establishing a Caribbean Court of Justice. Its supreme appellate court therefore remains the British Judicial Committee of the Privy Council. Indeed, of the signatories to the Agreement, as of December 2010, only Barbados has replaced appeals to Her Majesty in Council with the Caribbean Court of Justice.
In addition to the Eastern Caribbean Supreme Court, Antigua and Barbuda has a Magistrates\' Court, which deals with lesser civil and criminal cases.
## Movements
- Republicanism in Antigua and Barbuda
- Federalism in Antigua and Barbuda
- Barbudan independence movement
## Political pressure groups and leaders {#political_pressure_groups_and_leaders}
- Antigua Trades and Labour Union
- People\'s Democratic Movement
## International organisation participation {#international_organisation_participation}
- Organisation of African, Caribbean and Pacific States
- ALBA
- Caribbean Community
- Caribbean Development Bank
- Community of Latin American and Caribbean States
- Commonwealth of Nations
- United Nations Economic Commission for Latin America and the Caribbean
- Food and Agriculture Organization
- Group of 77
- International Bank for Reconstruction and Development
- International Civil Aviation Organization
- International Criminal Court
- International Confederation of Free Trade Unions
- International Red Cross and Red Crescent Movement
- International Fund for Agricultural Development
- International Finance Corporation
- International Federation of Red Cross and Red Crescent Societies
- International Labour Organization
- International Monetary Fund
- International Maritime Organization
- Intelsat (nonsignatory user)
- Interpol
- International Olympic Committee
- International Telecommunication Union
- Non-Aligned Movement (observer)
- Organization of American States
- Organisation of Eastern Caribbean States
- OPANAL
- United Nations
- United Nations Conference on Trade and Development
- UNESCO
- Universal Postal Union
- World Confederation of Labour
- World Federation of Trade Unions
- World Health Organization
- World Meteorological Organization
- World Trade Organization
| 2025-08-01T00:00:00 |
1,072 |
Telecommunications in Antigua and Barbuda
|
**Telecommunications in Antigua and Barbuda** are via media in the telecommunications industry.
## Telephone
**Telephones -- main lines in use:** 37,500 (2006)
: *country comparison to the world:* 168
**Telephones -- mobile cellular:** 110,200 (2006) (APUA PCS, Cable & Wireless, Digicel)
: *country comparison to the world:* 177
**Telephone system:**\
*domestic:* good automatic telephone system\
*international:* 3 fiber optic submarine cables (2 to Saint Kitts and 1 to Guadeloupe); satellite earth station -- 1 Intelsat (Atlantic Ocean)
## Radio
**Radio broadcast stations:** AM 4, FM 6, shortwave 0 (2002)
Band / Freq. Call Sign Brand City of license Notes
-------------- -------------------- ------------------------ ------------------------ ----------------------------------------------
AM 620 V2C ABS Radio and TV Saint John\'s, Antigua ABS; 5 kW
AM 1100 ZDK Radio ZDK Saint John\'s, Antigua Owner: Grenville Radio; 20 kW
AM 1160 Unknown Radio Lighthouse Saint John\'s, Antigua 10 kW
AM 1580 Unknown Unknown Judge Bay, Antigua 50 kW
FM 88.5 Unknown Power FM Saint John\'s, Antigua
FM 89.7 Unknown Catholic Radio Saint John\'s, Antigua 2 kW
FM 90.5 V2C-FM ABS Radio and TV Saint John\'s, Antigua repeats AM 620
FM 91.1 Unknown Observer Radio Saint John\'s, Antigua
FM 91.9 Unknown Hitz 91.9 Saint John\'s, Antigua
FM 92.3 Unknown Radio Lighthouse Saint John\'s, Antigua repeats AM 1160
FM 92.9 VYBZ-FM Vybz FM Saint John\'s, Antigua
FM 93.9 Unknown Caribbean SuperStation Saint John\'s, Antigua repeats Caribbean SuperStation from Trinidad
FM 95.7 Unknown Zoom Radio Saint John\'s, Antigua
FM 97.1 ZDK Radio ZDK Saint John\'s, Antigua repeats AM 1100
FM 98.5 Unknown Red Hot Radio Saint John\'s, Antigua
FM 99.1 Unknown Hit Radio Music Power Saint John\'s, Antigua
FM 100.1 Unknown (ZDKR-FM?) Sun FM Saint John\'s, Antigua
FM 101.5 Unknown Second Advent Radio Saint John\'s, Antigua 20 watts
FM 102.3 Unknown Variety Radio Saint John\'s, Antigua
FM 103.1 Unknown Life FM Codrington, Barbuda 1 kW
FM 103.9 Unknown Life FM Saint John\'s, Antigua repeats 103.1 Codrington
FM 104.3 Unknown Nice FM Codrington, Barbuda
FM 107.3 Unknown Crusader Radio Saint John\'s, Antigua
SW 3.255 mHz V2C ABS Radio and TV Saint John\'s, Antigua Repeats AM 620
: Radio Stations of Antigua and Barbuda
**Radios:** 36,000 (1997)
## Television
**Television broadcast stations:** 2 (1997) (including ABS-TV)
**Televisions:** 31,000 (1997)
## Internet
**Internet Service Providers (ISPs):** Cable & Wireless, Antigua Computer Technologies (ACT), Antigua Public Utilities Authority (APUA INET)
**Internet hosts:** 2,215 (2008)
: *country comparison to the world:* 140
**Internet users:** 60,000 (2007)
: *country comparison to the world:* 158
**Country codes:** AG
## Demographics
Q48 Ethnic Q55 Internet Use
------------------------ ------------------
Yes No
African descendent 47.42%
Caucasian/White 83.27%
East Indian/India 58.66%
Mixed (Black/White) 64.34%
Mixed (Other) 61.22%
Hispanic 31.78%
Syrian/Lebanese 60.77%
Other 59.46%
Don\'t know/Not stated 20.58%
Total 48.35%
: Internet Users by Ethnicity
Q48 Ethnic Q25 4 Internet access
------------------------ -----------------------
No Yes
African descendent 51.99%
Caucasian/White 14.56%
East Indian/India 36.63%
Mixed (Black/White) 39.47%
Mixed (Other) 41.76%
Hispanic 67.68%
Syrian/Lebanese 29.48%
Other 34.02%
Don\'t know/Not stated 53.86%
Total 50.83%
: Household internet access by ethnicity
| 2025-08-01T00:00:00 |
1,074 |
Antigua and Barbuda Defence Force
|
The **Antigua and Barbuda Defence Force** (**ABDF**) is the armed forces of Antigua and Barbuda. The ABDF has responsibility for several different roles: internal security, prevention of drug smuggling, the protection and support of fishing rights, prevention of marine pollution, search and rescue, ceremonial duties, assistance to government programs, provision of relief during natural disasters, assistance in the maintenance of essential services, and support of the police in maintaining law and order. The force entered its current form on 20 December 1995.
The ABDF is one of the world\'s smallest militaries, consisting of 245 personnel. The first militia in Antigua was established in the 1600s, having fought against the French capture of the island in 1666. The governor oversaw the force, and by 1820 the island had a 945-man militia. The island continued to maintain this force for much of the colonial era, and by 1 September 1981 the Antigua Volunteer Defence Force was renamed to the Antigua and Barbuda Defence Force preceding independence. The force has undergone various reforms, and the present force was reestablished on 1 June 1956.
## Organisation
The ABDF consists of five branches:
- Antigua and Barbuda Regiment -- comprises four line companies and is the infantry unit and fighting arm of the defence force.
- Service and Support Unit -- provides administrative, logistic and engineer support to the rest of the defence force.
- Coast Guard -- the maritime element of the defence force.
- Air Wing -- the aerial element of the defence force.
- Cadet Corps -- voluntary youth organisation.
### Defence Board {#defence_board}
The Defence Board is in charge of overseeing the leadership, management, and discipline of the Antigua and Barbuda Defence Force as well as all other matters pertaining to it. The Defence Board has the authority to govern its work, how it will carry out its duties, and the responsibilities of its members. It can also assign any member of the Board any authority or duty, by publishing a notice in the Official Gazette; consult with non-members as appropriate, including officers commanding units of the Force, regarding matters pertaining to their units; and the officers are required to attend the meetings as the Board requests; decide on the protocol to be followed in conducting its business; and provide for any other matter that it deems necessary or desirable for achieving the better performance of its functions.
### Officers
A person cannot be appointed to the force unless they have received a recommendation from a board, known as the Commissions Board in the Defence Act. This board is made up of the chairman, who is appointed by the Chief of Defence Staff; the Chairman of the Public Service Commission, or in his absence, the Vice Chairman of the Public Service Commission; and an individual appointed by the Defence Board for a duration determined by the Board. His Majesty has the authority to appoint people to the Antigua and Barbuda Defence Force, and the Governor-General may act in that capacity. A commission may be awarded for a predetermined amount of time or for an unlimited amount of time.
### Reserve forces {#reserve_forces}
There are two classes in the Antigua and Barbuda Defence Force Reserve. The soldiers enlisted, deemed to be enlisted, or re-engaged in accordance with this Part for service in that class; the Reserve soldiers of the second class who have, upon written application to the appropriate military authority, been accepted by that authority for service in the first class; and the soldiers transferred to the first class in accordance with section 31 of the Defence Act comprise the first class. The soldiers who are members of the second class by virtue of Part IV of the Defence Act, the officers who are appointed or transferred to that class, and the soldiers who are enlisted, deemed to be enlisted, or re-engaged in accordance with Part IX of the Defence Act for service in that class are all included in the second class.
Each officer and soldier in the first class of the Reserve is required to report for duty at the location and for the duration determined by the Defence Board. They are also required to meet all training-related requirements. Subject to any general directives from the Defence Board, the requirements of the related section may be disregarded in whole or in part with regard to any unit of the first class of the Reserve, as well as with regard to any individual officer or soldier of the first class of the Reserve, by his commanding officer. Nothing stops a Reserve officer or soldier from participating in optional training in addition to any mandated training.
The first class of the Reserve, or as many officers and soldiers of that class as the Board deems necessary, may be called out on temporary duty by the Defence Board when needed. Under section 203, officers and soldiers who are called out for duty are not required to serve for more than ninety days at a time. Because the worker is a Reserve member who is called out in accordance with the section, no employer may fire or give notice of termination to any worker. When an employer violates, they are guilty of a crime and face a maximum fine of \$5,000, a maximum sentence of two (2) years in jail, or both. This applies even in cases of summary conviction.
The Governor-General may, on the advice of the Prime Minister, by proclamation order that the Reserve, or any class thereof, be called out on permanent service in the event of a state of war, insurrection, hostilities, or public emergency; the Defence Board will then take appropriate action. When called out on permanent duty, every Reserve officer and soldier is eligible to stay on permanent duty until told otherwise. Every officer and soldier belonging to such a class, as the case may be, to the part of any class so called out, shall attend in person at the designated location whenever the whole or any part of the first class of the Reserve is called out on temporary or permanent service; or whenever the whole or any part of the second class of the Reserve is called out on permanent service. The Defence Board shall cause every officer or soldier subject to such call-out to be served with a notice requiring him to attend at the time and place specified in the notice in the event that the first class of the Reserve is called out on temporary service or the Reserve is called out on permanent service.
An officer of the Antigua and Barbuda Defence Force may file a summarily complaint against a person who willfully takes away pawns, wrongfully destroys or damages, carelessly loses anything issued to him as an officer or soldier of the Reserve, or willfully refuses or fails to deliver up anything issued to him as an officer or soldier as a debt owed to the Crown. This applies even if the amount exceeds the normal monetary limit on a magistrate\'s jurisdiction.
A Reserve soldier may be released at any point during the duration of their service in the Reserve by the appropriate military authority under the prescribed conditions.
## Enlistment and terms of service {#enlistment_and_terms_of_service}
A recruiting officer will not enlist anyone in the Force unless they are satisfied that the potential recruit has received, comprehended, and wishes to be enlisted after receiving a notice in the prescribed form from anyone who wants to join the regular Force. A recruiting officer is not allowed to enlist a minor under the age of eighteen into the regular force unless written consent has been obtained from at least one parent, from any parent who may have parental rights and powers over the minor, from any person whose whereabouts are known or can be determined with reasonable effort, or from any person who is in fact or legally responsible for the minor. For the purposes of the Defence Act, an individual who is willing to enlist will be considered to have reached, or not reached, the age of eighteen if the recruiting officer is satisfied---either through the production of a certified copy of an entry in the register of births, or by any other evidence that seems sufficient to them. The period of time that an individual may enlist in the regular force is as follows: in the case of an individual who is 18 years of age or older at the time of enlistment, a term of colour service that does not exceed 12 years as prescribed; in this case, the term of service in the Reserve will apply to the portion of the term that is prescribed as a term of colour service, and the remaining portion will apply to a term of service. In the case of an individual who is younger at the time of enlistment, the period of time that is prescribed will begin on the date that the individual reaches the age of eighteen years or a term not to exceed 12 years, as specified, starting on the day he reaches that age and consisting of the portion of it that is prescribed as a term of colour service and the remaining portion as a term in the reserve.
Any soldier of good character who has served their full term of colour service or who will be serving in the Reserve in two years may, with permission from the appropriate military authority, re-engage for an additional period of colour service and Reserve duty as prescribed; however, the additional period of colour service, when combined with the original period of colour service, may not exceed a total continuous period of 22 years colour service from the date of the soldier\'s original attestation or the date he became eighteen years old, whichever comes first. Any soldier who has completed 22 years of colour service may, if he so chooses and with the consent of the appropriate military authority, continue to serve in all capacities as if his colour service term had not yet expired. However, on the date that he notifies his commanding officer that he wishes to be discharged, he may be eligible for discharge at the end of the three-month period. Any soldier whose term of colour service expires during a public emergency, war, insurrection, hostilities, or other exigency of duty may be kept in the Force and have their service extended for an additional period of time as directed by the Defence Board and the appropriate military authority.
Every regular force soldier who is eligible for discharge will be released as soon as possible, subject to the Defence Act. However, until they are released, they are subject to military law as stipulated by the Act. When a regular force soldier is serving outside of Antigua and Barbuda at the time of his discharge, he has two options: if he wants to be discharged in Antigua and Barbuda, he will be sent there at no cost as soon as possible, and he will be released either when he arrives in Antigua and Barbuda or, if he agrees to a delay in discharge, six months after arriving; else, he will be released where he is currently serving. Releasing a soldier from the regular force requires authorization from the appropriate military authority, unless they are being released in accordance with a court-martial sentence. Upon their release from active duty, all regular force soldiers will receive a certificate of discharge that includes the necessary information. Every regular Force soldier who is scheduled to be transferred to the Reserve may do so in accordance with the Act, but they will remain subject to military law until they are transferred. When a regular Force soldier serving outside of Antigua and Barbuda is scheduled to be transferred to the Reserve, he will be sent there at no cost to him and will be transferred to the Reserve upon arrival, or within six months of his arrival if he agrees to a delay in transfer; he may, however, choose to be transferred to the Reserve without having to return to Antigua and Barbuda. When a regular Force soldier is being transferred to the Reserve, the appropriate military authority has the authority to immediately discharge him without providing a reason.
A court-martial sentence, a Defence Board order, or an order from an officer not lower than Major or a corresponding rank who has been given permission by the commanding officer may be the only ways that a warrant officer or non-commissioned officer\'s rank may be lowered. If a regular force warrant officer is demoted to the ranks, he or she may request to be discharged, barring a state of war, insurrection, hostilities, or public emergency. Anytime during the duration of the soldier\'s term of engagement, the competent military authority may release a regular force soldier for the prescribed reasons. Regular Force soldiers have the right to request their discharge at any point within three months of the date of their first attestation. If they do so, they will be released as soon as possible after paying a sum not to exceed EC\$500. However, they will still be subject to military law until their discharge under the Act. A soldier of the regular Force who was a member of a Commonwealth Force at any point within three months prior to the date of his first attestation is exempt from this.
## Deployments
- In 1983, fourteen men of the Antigua and Barbuda Defence Force were deployed to Grenada during the Operation Urgent Fury.
- In 1990, twelve soldiers were sent to Trinidad and Tobago after a failed coup attempt by a radical group against the constitutionally elected government headed by Prime Minister A.N.R. Robinson.
- In 1995, members of the Antigua and Barbuda Defence Force were deployed in Haiti as a part of Operation Uphold Democracy.
## Alliances
- -- Mercian Regiment
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Geography of Azerbaijan
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Azerbaijan is a country in the Caucasus region, situated at the juncture of Eastern Europe and West Asia. Three physical features dominate Azerbaijan: the Caspian Sea, whose shoreline forms a natural boundary to the east; the Greater Caucasus mountain range to the north; and the extensive flatlands at the country\'s center. About the size of Portugal or the US state of Maine, Azerbaijan has a total land area of approximately 86,600 sqkm, less than 1% of the land area of the former Soviet Union. Of the three Transcaucasian states, Azerbaijan has the greatest land area. Special administrative subdivisions are the Nakhchivan Autonomous Republic, which is separated from the rest of Azerbaijan by a strip of Armenian territory, and the Nagorno-Karabakh Autonomous Region, entirely within Azerbaijan. The status of Nagorno-Karabakh is disputed by Armenia, but is internationally recognized as territory of Azerbaijan.
Located in the region of the southern Caucasus Mountains, Azerbaijan borders the Caspian Sea to the east, Georgia and Russia to the north, Iran to the south, and Armenia to the southwest and west. A small part of Nakhchivan also borders Turkey to the northwest. The capital of Azerbaijan is the ancient city of Baku, which has the largest and best harbor on the Caspian Sea and has long been the center of the republic\'s oil industry.
## Topography and drainage {#topography_and_drainage}
The elevation changes over a relatively short distance from lowlands to highlands; nearly half the country is considered mountainous. Notable physical features are the gently undulating hills of the subtropical southeastern coast, which are covered with tea plantations, orange groves, and lemon groves; numerous mud volcanoes and mineral springs in the ravines of Kobustan Mountain near Baku; and coastal terrain that lies as much as twenty-eight meters below sea level.
Except for its eastern Caspian shoreline and some areas bordering Georgia and Iran, Azerbaijan is ringed by mountains. To the northeast, bordering Russia\'s Dagestan Autonomous Republic, is the Greater Caucasus range; to the west, bordering Armenia, is the Lesser Caucasus range. To the extreme southeast, the Talysh Mountains form part of the border with Iran. The highest elevations occur in the Greater Caucasus, where Mount Bazardüzü rises 4,466 meters above sea level. Eight large rivers flow down from the Caucasus ranges into the central Kura-Aras Lowlands, alluvial flatlands and low delta areas along the seacoast designated by the Azerbaijani name for the Mtkvari River (Kura) and its main tributary, the Aras. The Mtkvari, the longest river in the Caucasus region, forms the delta and drains into the Caspian a short distance downstream from the confluence with the Aras. The Mingechaur Reservoir, with an area of 605 square kilometers that makes it the largest body of water in Azerbaijan, was formed by damming the Kura in western Azerbaijan. The waters of the reservoir provide hydroelectric power and irrigation of the Kura--Aras plain. Most of the country\'s rivers are not navigable. About 15% of the land in Azerbaijan is arable.
## Mountains
The country\'s highest peak, Bazardüzü, rises to 4,485 m at the Azerbaijan-Russia border.
## Climate
### Temperature
The climate varies from subtropical and humid in the southeast to subtropical and dry in central and eastern Azerbaijan, continental and humid in the mountains, and continental and dry in Nakhchivan. Baku, on the Caspian, enjoys mild weather that averages 4 °C in January and 25 °C in July.
### Precipitation
Physiographic conditions and different atmosphere circulations admit 8 types of air currents including continental, sea, arctic, tropical currents of air that formulates the climate of the Republic. The maximum annual precipitation falls in Lenkeran (1,600 to) and the minimum in Absheron (200 to). The maximum daily precipitation of 334 mm was observed at the Bilieser Station in 1955.
## Environmental problems {#environmental_problems}
Air and water pollution are widespread and pose great challenges to economic development. Major sources of pollution include oil refineries and chemical and metallurgical industries, which in the early 1990s continued to operate as inefficiently as they had in the Soviet era. Air quality is extremely poor in Baku, the center of oil refining. Some reports have described Baku\'s air as the most polluted in the former Soviet Union, and other industrial centers suffer similar problems.
The Caspian Sea, including Baku Bay, has been polluted by oil leakages and the dumping of raw or inadequately treated sewage, reducing the yield of caviar and fish. In the Soviet period, Azerbaijan was pressed to use extremely heavy applications of pesticides to improve its output of scarce subtropical crops for the rest of the Soviet Union. The continued regular use of the pesticide DDT in the 1970s and 1980s was an egregious lapse, although that chemical was officially banned in the Soviet Union because of its toxicity to humans. Excessive application of pesticides and chemical fertilizers has caused extensive groundwater pollution and has been linked by Azerbaijani scientists to birth defects and illnesses. Rising water levels in the Caspian Sea, mainly caused by natural factors exacerbated by man-made structures, have reversed the decades-long drying trend and now threaten coastal areas; the average level rose 1.5 meters between 1978 and 1993. Because of the Nagorno-Karabakh conflict, large numbers of trees were felled, roads were built through pristine areas, and large expanses of agricultural land were occupied by military forces.
Like other former Soviet republics, Azerbaijan faces a gigantic environmental cleanup complicated by the economic uncertainties left in the wake of the Moscow-centered planning system. The Committee for the Protection of the Natural Environment is part of the Azerbaijani government, but in the early 1990s it was ineffective at targeting critical applications of limited funds, establishing pollution standards, or monitoring compliance with environmental regulations. Early in 1994, plans called for Azerbaijan to participate in the international Caspian Sea Forum, sponsored by the European Union (EU).
Natural hazards:
: Droughts and floods; some lowland areas threatened by rising levels of the Caspian Sea
Environment -- current issues:
: Local scientists consider the Abseron Yasaqligi (Apsheron Peninsula) (including Baky and Sumqayit) and the Caspian Sea to be the ecologically most devastated area in the world because of severe air, water, and soil pollution; soil pollution results from the use of DDT as a pesticide and also from toxic defoliants used in the production of cotton.
Environment -- international agreements
:\* Party to: Air Pollution, Biodiversity, Climate Change, Desertification, Endangered Species, Hazardous Wastes, Marine Dumping, Ozone Layer Protection, Ship Pollution, Wetlands
## Area and boundaries {#area_and_boundaries}
Area:
:\* Total: 86,600 sqkm
:\*\**country rank in the world:* 113rd
:\* Land: 82,629 sqkm
:\* Water: 3,971 sqkm
:\* Note: Includes the exclave of Nakhchivan Autonomous Republic and the Nagorno-Karabakh region; the region\'s autonomy was abolished by Azerbaijani Supreme Soviet on November 26, 1991.
Area comparative
:\* Australia comparative: approximately `{{sfrac|2|7}}`{=mediawiki} larger than Tasmania
:\* Canada comparative: approximately `{{sfrac|1|5}}`{=mediawiki} larger than New Brunswick
:\* United Kingdom comparative: slightly larger than Scotland
:\* United States comparative: slightly smaller than Maine
:\* EU comparative: slightly smaller than Portugal
Land boundaries\
\* Total: 2,468 km\
\* Border countries:
:\*\*Armenia (with Azerbaijan-proper) 566 km
:\*\* Armenia (with Azerbaijan-Nakhchivan exclave) 221 km
:\*\* Georgia 428 km
:\*\*Iran (with Azerbaijan-proper) 432 km
:\*\*Iran (with Azerbaijan-Nakhchivan exclave) 700 km
:\*\*Russia 338 km
:\*\*Turkey 17 km
Coastline
:\*0 km
:\*\*Note: Azerbaijan borders the Caspian Sea. Its coastline with the Caspian Sea is 713 km.
Maritime claims
:\* Border disputes with Turkmenistan, Kazakhstan, Iran, and Russia
Terrain
:\* large, flat lowland (much of it below sea-level) with Great Caucasus Mountains to the north, uplands in the west
Elevation extremes\
\* Lowest point: Caspian Sea −28 m\
\* Highest point: Bazardüzü 4466 m (on the border with Russia)\
\* Highest peak entirely within Azeri territory: Shah Dagi 4,243 m
### Islands
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Geography of Armenia
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Armenia is a landlocked country in the South Caucasus region of the Caucasus. The country is geographically located in West Asia, within the Armenian plateau. Armenia is bordered on the north and east by Georgia and Azerbaijan and on the south and west by Iran, Azerbaijan\'s exclave Nakhchivan, and Turkey.
The terrain is mostly mountainous, with fast flowing rivers and few forests. The climate is highland continental: hot summers and cold winters. The land rises to 4,090 m above sea-level at Mount Aragats.
## Physical environment {#physical_environment}
Armenia is located in the southern Caucasus, the region southwest of Russia between the Black Sea and the Caspian Sea. Modern Armenia occupies part of historical Armenia, whose ancient centers were in the valley of the Araks River and the region around Lake Van in Turkey. Armenia is bordered on the north by Georgia, on the east by Azerbaijan, on the south by Iran, and on the west by Turkey.
In Armenia forest cover is around 12% of the total land area, equivalent to 328,470 hectares (ha) of forest in 2020, down from 334,730 hectares (ha) in 1990. In 2020, naturally regenerating forest covered 310,000 hectares (ha) and planted forest covered 18,470 hectares (ha). Of the naturally regenerating forest 5% was reported to be primary forest (consisting of native tree species with no clearly visible indications of human activity) and around 0% of the forest area was found within protected areas. For the year 2015, 100% of the forest area was reported to be under public ownership.
## Topography and drainage {#topography_and_drainage}
`{{See also|List of rivers of Armenia|List of lakes of Armenia|Mountains of Armenia}}`{=mediawiki}
Twenty-five million years ago, a geological upheaval pushed up the Earth\'s crust to form the Armenian Plateau, creating the complex topography of modern Armenia. The Lesser Caucasus range extends through northern Armenia, runs southeast between Lake Sevan and Azerbaijan, then passes roughly along the Armenian-Azerbaijani border to Iran. Thus situated, the mountains make travel from north to south difficult. Geological turmoil continues in the form of devastating earthquakes, which have plagued Armenia. In December 1988, the second largest city in the republic, Leninakan (now Gyumri), was heavily damaged by a massive quake that killed more than 25,000 people.
About half of Armenia\'s area of approximately 29,743 km2 has an elevation of at least 2000 m, and only 3% of the country lies below 650 m. The lowest points are in the valleys of the Araks River and the Debed River in the far north, which have elevations of 380 and, respectively. Elevations in the Lesser Caucasus vary between 2640 and. To the southwest of the range is the Armenian Plateau, which slopes southwestward toward the Araks River on the Turkish border. The plateau is masked by intermediate mountain ranges and extinct volcanoes. The largest of these, Mount Aragats, 4090 m high, is also the highest point in Armenia. Most of the population lives in the western and northwestern parts of the country, where the two major cities, Yerevan and Gyumri, are located.
The valleys of the Debed and Akstafa rivers form the chief routes into Armenia from the north as they pass through the mountains. Lake Sevan, 72.5 km across at its widest point and 376 km long, is by far the largest lake. It lies 1900 m above sea level on the plateau and is 1279.18 km2 large. Other main lakes are: Arpi, 7.5 km2, Sev, 2 km2, Akna 0.8 km2. Terrain is most rugged in the extreme southeast, which is drained by the Bargushat River, and most moderate in the Araks River valley to the extreme southwest. Most of Armenia is drained by the Araks or its tributary, the Hrazdan, which flows from Lake Sevan. The Araks forms most of Armenia\'s border with Turkey and Iran, while the Zangezur Mountains form the border between Armenia\'s southern province of Syunik and Azerbaijan\'s adjacent Nakhchivan Autonomous Republic.
## Climate
Temperatures in Armenia generally depend upon elevation. Mountain formations block the moderating climatic influences of the Mediterranean Sea and the Black Sea, creating wide seasonal variations with cold snowy winters, and warm to hot summers. On the Armenian Plateau, the mean midwinter temperature is 0 °C to −15 °C, and the mean midsummer temperature is 15 °C to 30 °C. Average precipitation ranges from 250 mm per year in the lower Araks River valley to 800 mm at the highest altitudes. Despite the harshness of winter in most parts (with frosts reaching -40 °C and lower in Shirak region), the fertility of the plateau\'s volcanic soil made Armenia one of the world\'s earliest sites of agricultural activity.
## Area and boundaries {#area_and_boundaries}
**Area**:\
*total:* 29,743 km^2^
: *country comparison to the world:* 143
*land:* 28,203 km^2^\
*water:* 1,540 km^2^
**Area comparative**
- Australia comparative: about one third (33%) the size of Tasmania
- Canada comparative: greater than half (56%) the size of Nova Scotia
- Turkey comparative: about a quarter (24%) smaller than the size of Konya Province.
- United Kingdom comparative: about one third larger (30%) than Wales
- United States comparative: slightly smaller (7%) than Maryland
- EU comparative: slightly smaller (8%) than Belgium
**Land boundaries**:\
*total:* 1,570 km\
*border countries:*
Azerbaijan 566 km, Azerbaijan-Nakhchivan exclave 221 km, Georgia 219 km, Iran 44 km, Turkey 311 km
**Coastline:**
0 km (landlocked)
**Elevation extremes:**\
*lowest point:* 375m\
*highest point:* Mount Aragats 4,090 m
**Extreme points of Armenia:**\
*North:* Tavush (41 17 N 45 0 E type:landmark_region:AM)\
*South:* Syunik (38 49 N 46 10 E type:landmark_region:AM)\
*West:* Shirak (41 5 N 43 27 E type:landmark_region:AM)\
*East:* Syunik (39 13 N 46 37 E type:landmark_region:AM)
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Politics of Armenia
|
The **politics of Armenia** take place in the framework of the parliamentary representative democratic republic of Armenia, whereby the president of Armenia is the head of state and the prime minister of Armenia the head of government, and of a multi-party system. Executive power is exercised by the president and the Government. Legislative power is vested in both the Government and Parliament.
## History
Armenia became independent from the Russian Empire on 28 May 1918 as the *Republic of Armenia*, later referred as First Republic of Armenia. About a month before its independence Armenia was part of short lived Transcaucasian Democratic Federative Republic. Suffering heavy losses during the Turkish invasion of Armenia and after the Soviet invasion of Armenia, the government of the First Republic resigned on 2 December 1920. Soviet Russia reinstalled its control over the country, which later became part of the Transcaucasian SFSR. The TSFSR was dissolved in 1936 and Armenia became a constituent republic of the Soviet Union known as the Armenian SSR, later also referred as the *Second Republic of Armenia*.
During the dissolution of the Soviet Union the population of Armenia voted overwhelmingly for independence following the 1991 Armenian independence referendum. It was followed by a presidential election in October 1991 that gave 83% of the votes to Levon Ter-Petrosyan. Earlier in 1990, when the National Democratic Union party defeated the Armenian Communist Party, he was elected Chairman of the Supreme Council of Armenia. Ter-Petrosyan was re-elected in 1996. Following public discontent and demonstrations against his policies on Nagorno-Karabakh, the President resigned in January 1998 and was replaced by Prime Minister Robert Kocharyan, who was elected as second President in March 1998. Following the assassination of Prime Minister Vazgen Sargsyan, parliament Speaker Karen Demirchyan and six other officials during parliament seating on 27 October 1999, a period of political instability ensued during which an opposition headed by elements of the former Armenian National Movement government attempted unsuccessfully to force Kocharyan to resign. In May 2000, Andranik Margaryan replaced Aram Sargsyan (a brother of assassinated Vazgen Sargsyan) as Prime Minister.
Kocharyan\'s re-election as president in 2003 was followed by widespread allegations of ballot-rigging. He went on to propose controversial constitutional amendments on the role of parliament. These were rejected in a referendum the following May. Concurrent parliamentary elections left Kocharyan\'s party in a very powerful position in the parliament. There were mounting calls for the President\'s resignation in early 2004 with thousands of demonstrators taking to the streets in support of demands for a referendum of confidence in him.
The Government of Armenia\'s stated aim is to build a Western-style parliamentary democracy. However, international observers have questioned the fairness of Armenia\'s parliamentary and presidential elections and constitutional referendum between 1995 and 2018, citing polling deficiencies, lack of cooperation by the Electoral Commission, and poor maintenance of electoral lists and polling places. Armenia is considered one of the most democratic nations of the Commonwealth of Independent States and the most democratic in the Caucasus region.
The observance of human rights in Armenia is uneven and is marked by shortcomings. Police brutality allegedly still goes largely unreported, while observers note that defendants are often beaten to extract confessions and are denied visits from relatives and lawyers. Public demonstrations usually take place without government interference, though one rally in November 2000 by an opposition party was followed by the arrest and imprisonment for a month of its organizer. Freedom of religion is not always protected under existing law. Nontraditional churches, especially the Jehovah\'s Witnesses, have been subjected to harassment, sometimes violently. All churches apart from the Armenian Apostolic Church must register with the government, and proselytizing was forbidden by law, though since 1997 the government has pursued more moderate policies. The government\'s policy toward conscientious objection is in transition, as part of Armenia\'s accession to the Council of Europe.
Armenia boasts a good record on the protection of national minorities, for whose representatives (Assyrians, Kurds, Russians and Yazidis) four seats are reserved in the National Assembly. The government does not restrict internal or international travel.
### Transition to a parliamentary republic {#transition_to_a_parliamentary_republic}
In December 2015, the country held a referendum which approved transformation of Armenia from a semi-presidential to a parliamentary republic.
As a result, the president was stripped of his veto faculty and the presidency was downgraded to a figurehead position elected by parliament every seven years. The president is not allowed to be a member of any political party and re-election is forbidden.
Skeptics saw the constitutional reform as an attempt of third president Serzh Sargsyan to remain in control by becoming Prime Minister after fulfilling his second presidential term in 2018.
In March 2018, the Armenian parliament elected Armen Sarkissian as the new President of Armenia. The controversial constitutional reform to reduce presidential power was implemented, while the authority of the prime minister was strengthened. In May 2018, parliament elected opposition leader Nikol Pashinyan as the new prime minister. His predecessor Serzh Sargsyan resigned two weeks earlier following widespread anti-government demonstrations.
In June 2021, early parliamentary elections were held. Nikol Pashinyan\'s Civil Contract party won 71 seats, while 29 went to the Armenia Alliance headed by former President Robert Kocharyan. The I Have Honor Alliance, which formed around another former president, Serzh Sargsyan, won seven seats. After the election, Armenia\'s acting Prime Minister Nikol Pashinyan was officially appointed to the post of prime minister by the country\'s president Armen Sarkissian. In January 2022, Armenian President Armen Sarkissian resigned from office, stating that the constitution does no longer give the president sufficient powers or influence. On 3 March 2022, Vahagn Khachaturyan was elected as the fifth president of Armenia in the second round of parliamentary vote.
## Government
\|President \|Vahagn Khachaturyan \|Independent \|13 March 2022 \|- \|Prime Minister \|Nikol Pashinyan \|Civil Contract \|8 May 2018 \|}
## Legislative branch {#legislative_branch}
The unicameral National Assembly of Armenia (*Azgayin Zhoghov*) is the legislative branch of the government of Armenia.
Before the 2015 Armenian constitutional referendum, it was initially made of 131 members, elected for five-year terms: 41 members in single-seat constituencies and 90 by proportional representation. The proportional-representation seats in the National Assembly are assigned on a party-list basis among those parties that receive at least 5% of the total of the number of the votes.
Following the 2015 referendum, the number of MPs was reduced from the original 131 members to 101 and single-seat constituencies were removed.
## Political parties and elections {#political_parties_and_elections}
As of January 2025, there are 123 political parties registered in Armenia. The electoral threshold is currently set at 5% for single parties and 7% for blocs.
### Latest national elections {#latest_national_elections}
### Latest presidential elections {#latest_presidential_elections}
## Independent agencies {#independent_agencies}
Independent of three traditional branches are the following independent agencies, each with separate powers and responsibilities:
- the Constitutional Court of Armenia
- the Central Electoral Commission of Armenia
- the Human Rights Defender of Armenia
- the Central Bank of Armenia
- the Prosecutor General of Armenia
- the Audit Chamber of Armenia
## Corruption
Transparency International\'s 2024 Corruption Perceptions Index ranked Armenia 60th out of 180 in the world with 47 points. This has pushed the country up from being ranked at 60th in 2020 and 58th in 2021. According to Transparency International, Armenia has improved significantly on the Corruption Perception Index since 2012, especially since the 2018 revolution, the country has taken steps to counter corruption. Further mentioning that \"Armenia has taken a gradual approach to reform, resulting in steady and positive improvements in anti-corruption. However, safeguarding judicial independence and ensuring checks and balances remain critical first steps in its anti-corruption efforts. The effectiveness of those efforts is additionally challenged by the current political and economic crisis as a result of the recent Nagorno Karabakh conflict and the subsequent protests against Prime Minister Nikol Pashinyan over a ceasefire deal\".
In 2008, Transparency International reduced its Corruption Perceptions Index for Armenia from 3.0 in 2007 to 2.9 out of 10 (a lower score means more perceived corruption); Armenia slipped from 99th place in 2007 to 109th out of 180 countries surveyed (on a par with Argentina, Belize, Moldova, Solomon Islands, and Vanuatu).
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Transport in Armenia
|
This article considers **transport in Armenia**.
## Railways
### Total
in common carrier service; does not include industrial lines
### Broad gauge {#broad_gauge}
850 km of `{{RailGauge|1520mm}}`{=mediawiki} gauge (850 km electrified) (1995) There is no service south of Yerevan.
City with metro system: Yerevan
### International links {#international_links}
- Azerbaijan - closed - same gauge
- Georgia - yes - same gauge
- Iran - via Azerbaijan - closed - break of gauge - `{{RailGauge|1520mm}}`{=mediawiki}/`{{RailGauge|sg}}`{=mediawiki}
- Turkey - closed - break of gauge -`{{RailGauge|1520mm}}`{=mediawiki}/`{{RailGauge|sg}}`{=mediawiki}
Most of the cross-border lines are currently closed due to political problems. However, there are daily inbound and outbound trains connecting Tbilisi and Yerevan. Departing from Yerevan railway station trains connect to both Tbilisi and Batumi. From neighboring Georgia, trains depart to Yerevan from Tbilisi railway station. Within Armenia, new electric trains connect passengers from Yerevan to Armenia\'s second-largest city of Gyumri. The new trains run four times a day and the journey takes approximately two hours.
There is also discussion to establish a rail link between Yerevan and Tehran. Armenia is pursuing funding from the Asian Development Bank to launch the construction of this infrastructure project. The completion of the project could establish a major commodities transit corridor and would serve as the shortest transportation route between Europe and the Persian Gulf. In June 2019, Iranian president Hassan Rouhani backed this project and stated that "we want the Persian Gulf and the Gulf of Oman to be connected to the Black Sea, and one of the ways to make this happen is through Iran, Armenia and Georgia."
### Metros
The capital city of Armenia, Yerevan, is serviced by the Yerevan Metro. The system was launched in 1981, and like most former Soviet Metros, its stations are very deep (20--70 meters underground) and intricately decorated with national motifs. The metro runs on a 13.4 kilometers (8.3 mi) line and currently serves 10 active stations. Trains run every five minutes from 6:30 a.m. until 11 p.m. local AMT time. As of 2017, the annual ridership of the metro is 16.2 million passengers. Free Wi-Fi is available at all stations and some trains.
### Trams
Yerevan tram (Armenian: *Երևանի տրամվայ*) was a tram system previously operating in Yerevan, the capital of Armenia. It was opened on 29 September 1906 in the form of a city wagonway. In the second half of the 20th century, the tram system had up to 12 routes, which were served by 3 depots. Trams were operated until 21 January 2004.
#### History
The only city in Armenia where a tram ever existed was Yerevan. On 29 September 1906, the Yerevan horse wagonway was opened. This type of narrow-gauge wagonway existed until August 1918, when the tram was destroyed during World War I.
On 12 January 1933, a wide-gauge electric tram was launched. The number of tram cars increased by 25% on average every five years, in 1933 it was 16, then in 1945 there were 77 cars, and in 1965 - 222 cars. Two types of trams were used, the 71-605 and the RVZ-6M2, both were Soviet made. Since the cost of the tram was 2.4% higher than that of buses, as well as due to expensive electricity and problems arising when the tram crossed the Great Bridge of Hrazdan in Yerevan, route #7 (Erebuni - Zeytun) was closed on 20 June 2003.
Most of the tracks have been removed and the trams have been turned into scrap. The tram depot is used by various private enterprises, and the substation currently serves the Yerevan trolleybus.
## Buses
### International connections {#international_connections}
Land borders are open with both Georgia and Iran. Yerevan Central Bus Station, also known as Kilikia Bus Station is the main bus terminal in Yerevan with buses connecting to both internal and international destinations. There are daily bus connections between Yerevan and Tbilisi and Yerevan and Tehran. Approximately three times daily, buses depart from Yerevan Central Bus Station to Stepanakert, the capital of the partially recognized state of Artsakh. There are also scheduled bus routes which connect Yerevan with Kyiv, Moscow, Saint Petersburg as well as several other cities across Russia. It is also possible to connect to Chișinău Moldova, Minsk Belarus and other cities in Eastern Europe from Yerevan through connecting bus routes via Georgia and Ukraine. In addition, there is a once a week bus service to Istanbul via Georgia. In June 2019, a new bus route from Baghdad to Yerevan via Iran began.
### Local connections {#local_connections}
The Armenian bus network connects all major cities, towns, and villages throughout the country. In larger cities and towns such as Yerevan, Gyumri, Vanadzor and Armavir, bus stations are equipped with a waiting room and a ticket office, in other towns bus stations may not have shelters. Most of the routes are operated by GAZelle minivans with a capacity of 15 passengers, some routes are operated by soviet bus producer LiAZ (Russia). Yerevan itself has a large integrated bus network, with a newly acquired bus fleet, passengers are able to connect from one end of the city to the other. Wi-Fi is available on most city buses. Despite this, buses often have difficulty meeting the demand for capacity, mainly in Yerevan, where vehicles are typically overcrowded. There are no night services between 11 p.m. and 6 a.m. There is no ticket system in the country, passengers pay in cash to drivers. Passengers on the national bus network pay before boarding, passengers on the Yerevan bus network pay after the ride, while leaving the vehicle. Timetables and fares are published on [Transport for Armenia](https://t-armenia.com/).
From Yeritasardakan metro station in downtown Yerevan, travelers can take the 201 airport shuttle, which goes directly to Zvartnots International Airport, which takes approximately 20 minutes from the city center.
## Roadways
*Main article: Roads in Armenia* `{{See also|Road signs in Armenia}}`{=mediawiki} Since independence, Armenia has been developing its internal highway network. The \"North-South Road Corridor Investment Program\" is a major infrastructure project which aims at connecting the southern border of Armenia with its northern by means of a 556 km-long Meghri-Yerevan-Bavra highway. It is a major US\$1.5 billion infrastructure project funded by the Asian Development Bank, European Investment Bank and the Eurasian Development Bank. When completed, the highway will provide access to European countries via the Black Sea. It could also eventually interconnect the Black Sea ports of Georgia with the major ports of Iran, thus positioning Armenia in a strategic transport corridor between Europe and Asia. Armenia is pursuing further loans from China as part of the Belt and Road Initiative to complete the north--south highway.
Armenia connects to European road networks via the International E-road network through various routes such as; European route E117, European route E691, European route E001 and European route E60. Armenia also connects to the Asian Highway Network through routes AH81, AH82 and AH83.
The number of insured registered cars in Armenia has grown from 390,457 in 2011 to 457,878 in 2015.
### Total {#total_1}
8,800 km\
World Ranking: 112
### Paved
8,800 km (including 1,561 km of expressways)
### Unpaved
0 km (2006 est.)
## Pipelines
Natural gas 3,838 km (2017)
## Ports and harbors {#ports_and_harbors}
Cargo shipments to landlocked Armenia are routed through ports in Georgia and Turkey.
## Airports
`{{See also| List of airports in Armenia| List of the busiest airports in Armenia| List of airlines of Armenia}}`{=mediawiki}
Air transportation in Armenia is the most convenient and comfortable means of getting into the country. There are large international airports that accept both external and domestic flights throughout the Republic. As of 2020, 11 airports operate in Armenia. However, only Yerevan\'s Zvartnots International Airport and Gyumri\'s Shirak Airport are in use for commercial aviation. There are three additional civil airports currently under reconstruction in Armenia, including Syunik Airport, Stepanavan Airport, and Goris Airport. The leading Armenian airlines in operation are Armenia Aircompany and Armenia Airways.
There are plenty of air connections between Yerevan and other regional cities, including Athens, Barcelona, Beirut, Berlin, Bucharest, Brussels, Damascus, Doha, Dubai, Istanbul, Kyiv, Kuwait City, London, Milan, Minsk, Moscow, Paris, Prague, Riga, Rome, Tehran, Tel-Aviv, Tbilisi, Vienna, Venice, and Warsaw, as well as daily connections to most major cities within the CIS region. Statistics show that the number of tourists arriving in the country by air transportation increases yearly. In 2018, passenger flow at the two main airports of Armenia reached a record high of 2,856,673 million people. In December 2019, yearly passenger flow exceeded 3,000,000 million people for the first time in Armenia\'s history.
In November 2019, the creation of a Free Route Airspace (FRA) between Armenia and Georgia was announced. The process has been carried out through the joint efforts of the General Department of Civil Aviation of Armenia, the Georgian Civil Aviation Administration and Eurocontrol. The Free Route Airspace between the two South Caucasus countries will increase flights to around 40,000 annually.
Country comparison to the world: 153
### Airports - with paved runways {#airports___with_paved_runways}
Total: 10
: Over 3,047 m (9,900 feet): 2
: 1,524 to 2,437 m (7,920 feet): 2
: 914 to 1,523 m (4,950 feet): 4
: Under 914 m: 2 (as of 2008)
### Airports - with unpaved runways {#airports___with_unpaved_runways}
Total: 1
: 1,524 to 2,437 m: 0
: 914 to 1,523 m: 1
: under 914 m: 0 (as of 2008)
## Heliports
Armenia maintains a number of both military and civilian heliports. The main military heliport is located on the premises of Erebuni Airport in Yerevan. Meanwhile, the company Armenian Helicopters, based at Zvartnots Airport in Yerevan, offers charter flights within Armenia and to certain neighboring countries, including Georgia, Russia, and Turkey. Helicopter services are delivered with the US-made Robinson R66 and the European AIRBUS EC130T2 choppers. Flights can be carried out as scheduled or on individual routes.
## Aerial tramways {#aerial_tramways}
The Wings of Tatev is currently the world\'s longest reversible aerial tramway which holds the record for longest non-stop double-track cable car and is located in the town of Halidzor.
In October 2019, it was announced that investors were interested in creating an aerial tramway in the capital, Yerevan.
## International transport agreements {#international_transport_agreements}
Armenia cooperates in various international transport-related organizations and agreements, including the following:
- Eurocontrol
- European Aviation Safety Agency (Pan-European Partner)
- European Civil Aviation Conference
- European Common Aviation Area
- International Civil Aviation Organization
- International Road Transport Union
- International Transport Forum
- International Union of Railways (Associate member)
- Montreal Convention
- TIR Convention
- TRACECA
- Trans-European Transport Networks
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Demographics of American Samoa
|
**Demographics of American Samoa** include population density, ethnicity, education level, health of the populace, economic status, religious affiliations and other aspects. American Samoa is an unincorporated territory of the United States located in the South Pacific Ocean.
## Population
The statistics from 1900 to 1950 and every decennial census are from the U.S. Census Bureau. There was no census taken in 1910, but a special census taken in 1912. Beginning with the 1930 Census, Swain Island is included in the population count for American Samoa. The remaining statistics are from the World Factbook, unless otherwise indicated.
- Approximately 55,212, but the Factbook states 49,437 (2020 estimate). About 65% of the population are U.S. nationals, of whom at least 10% are U.S. citizens. Of the foreign-born population, 81% are from Samoa, 9% are from other parts of Oceania, and 9% are from Asia.
## Structure of the population {#structure_of_the_population}
Age Group Male Female Total \%
----------- -------- -------- -------- ---------
Total 28 164 27 355 55 519 100
0--4 3 417 3 194 6 611 11.91
5--9 3 470 3 065 6 535 11.77
10--14 3 214 3 065 6 279 11.31
15--19 3 218 3 078 6 296 11.34
20--24 1 944 1 947 3 891 7.01
25--29 1 670 1 654 3 324 5.99
30--34 1 726 1 784 3 510 6.32
35--39 1 845 1 764 3 609 6.50
40--44 1 793 1 807 3 600 6.48
45--49 1 673 1 716 3 389 6.10
50--54 1 335 1 344 2 679 4.83
55--59 1 011 1 038 2 049 3.69
60--64 755 725 1 480 2.67
65--69 500 460 960 1.73
70--74 321 333 654 1.18
75--79 155 182 337 0.61
80--84 76 130 206 0.37
85+ 41 69 110 0.20
Age group Male Female Total Percent
0--14 10 101 9 324 19 425 34.99
15--64 16 970 16 857 33 827 60.93
65+ 1 093 1 174 2 267 4.08
## Vital statistics {#vital_statistics}
### Registered births and deaths {#registered_births_and_deaths}
Year Population Live births Deaths Natural increase Crude birth rate Crude death rate Rate of natural increase Total Fertility Rate
------ ------------ ------------- -------- ------------------ ------------------ ------------------ -------------------------- ----------------------
2001 59,400 1,655 239 1,416 27.9 4.0 23.9 3.50
2002 60,800 1,629 295 1,334 26.8 4.9 21.9 3.86
2003 62,600 1,608 257 1,351 25.7 4.1 21.6 3.85
2004 64,100 1,713 289 1,424 26.7 4.5 22.2 4.14
2005 65,500 1,720 279 1,441 26.3 4.3 22.0 3.92
2006 66,900 1,442 267 1,175 21.6 4.0 17.6 3.52
2007 68,200 1,293 251 1,042 19.0 3.7 15.3 2.87
2008 69,200 1,338 240 1,098 19.3 3.5 15.8 2.91
2009 70,100 1,375 324 1,051 19.6 4.6 15.0 2.86
2010 67,380 1,279 247 1,032 19.0 3.7 15.3 3.11
2011 64,292 1,287 283 1,004 20.0 4.4 15.6 3.10
2012 63,596 1,175 282 893 18.5 4.4 14.1 2.85
2013 62,610 1,161 270 891 18.5 4.3 14.2 2.61
2014 61,811 1,084 259 825 17.5 4.2 13.3 2.60
2015 60,863 1,096 314 782 18.0 5.2 12.8 2.55
2016 60,200 1,013 280 733 16.8 4.7 12.1 2.69
2017 60,300 1,001 310 691 16.6 5.1 11.5 2.59
2018 59,600 921 298 623 15.5 5.0 10.5
2019 58,500 840 278 562 14.4 4.8 9.6
2020 49,841 734 322 412 14.7 6.5 8.2
2021 51,561 706 331 375 13.7 6.4 7.3
2022 51,269 706 399 307 13.8 7.8 6.0
2023 737 356 381 13.8 6.7 7.1
: 21st-century demography of American Samoa
## Ethnic groups {#ethnic_groups}
- Pacific Islander 92.6% (includes Samoan 88.9%, Tongan 2.9%, other 0.8%)
- Asian 3.6% (includes Filipino 2.2%, other 1.4%)
- Mixed 2.7%
- Other 1.2% (2010 est.)
## Languages
Native languages include:
- Samoan 88.6%
- English 3.9%
- Tongan 2.7%
- Other Pacific islander 3%
- Other 1.8% (2010 est.)
English proficiency is very high.
## Religion
- Christian 98.3%
- Other 1%
- Unaffiliated 0.7% (2010 est.)
Major Christian denominations on the island include the Congregational Christian Church in American Samoa, the Catholic Church, the Church of Jesus Christ of Latter-day Saints and the Methodist Church of Samoa. Collectively, these churches account for the vast majority of the population.
J. Gordon Melton in his book claims that the Methodists, Congregationalists with the London Missionary Society, and Catholics led the first Christian missions to the islands. Other denominations arrived later, beginning in 1895 with the Seventh-day Adventists, various Pentecostals (including the Assemblies of God), Church of the Nazarene, Jehovah\'s Witnesses, and the Church of Jesus Christ of Latter-day Saints.
The World Factbook 2010 estimate shows the religious affiliations of American Samoa as 98.3% Christian, other 1%, unaffiliated 0.7%. World Christian Database 2010 estimate shows the religious affiliations of American Samoa as 98.3% Christian, 0.7% agnostic, 0.4% Chinese Universalist, 0.3% Buddhist, and 0.3% Baháʼí.
According to Pew Research Center, 98.3% of the total population is Christian. Among Christians, 59.5% are Protestant, 19.7% are Catholic and 19.2% are other Christians. A major Protestant church on the island, gathering a substantial part of the local Protestant population, is the Congregational Christian Church in American Samoa, a Reformed denomination in the Congregationalist tradition. `{{As of|2017|8}}`{=mediawiki}, The Church of Jesus Christ of Latter-day Saints website claims membership of 16,180 or one-quarter of the whole population, with 41 congregations, and 4 family history centers in American Samoa. The Jehovah\'s Witnesses claim 210 \"ministers of the word\" and 3 congregations.
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Politics of American Samoa
|
**Politics of American Samoa** takes place in a framework of a presidential representative democratic dependency, whereby the governor is the head of government, and of a pluriform multi-party system. American Samoa is an unincorporated and unorganized territory of the United States, administered by the Office of Insular Affairs, U.S. Department of the Interior. Its constitution was ratified in 1966 and came into effect in 1967. Executive power is discharged by the governor and the lieutenant governor. Legislative power is vested in the two chambers of the legislature. The party system is based on the United States party system. The judiciary is independent of the executive and the legislature.
There is also the traditional village politics of the Samoan Islands, the *\[\[fa\'amatai\]\]* and the *\[\[faʻa Sāmoa\]\]*, which continues in American Samoa and in independent Samoa, and which interacts across these current boundaries. The *faʻa Sāmoa* is the language and customs, and the *fa\'amatai* the protocols of the *\[\[fono\]\]* (council) and the chiefly system. The *italic=no* and the *fono* take place at all levels of the Samoan body politic, from the family, to the village, to the region, to national matters. The *matai* (chiefs) are elected by consensus within the *fono* of the extended family and village(s) concerned. The *matai* and the *fono* (which is itself made of *matai*) decide on distribution of family exchanges and tenancy of communal lands. The majority of lands in American Samoa and independent Samoa are communal. A *matai* can represent a small family group or a great extended family that reaches across islands, and to both American Samoa and independent Samoa.
## Government
The government of American Samoa is defined under the Constitution of American Samoa. As an unincorporated territory, the Ratification Act of 1929 vested all civil, judicial, and military powers in the president, who in turn delegated authority to the secretary of the interior in `{{Executive Order|10264}}`{=mediawiki}. The secretary promulgated the Constitution of American Samoa which was approved by a constitutional convention of the people of American Samoa and a majority of the voters of American Samoa voting at the 1966 election, and came into effect in 1967.
The governor of American Samoa is the head of government and along with the lieutenant governor of American Samoa is elected on the same ticket by popular vote for four-year terms.
The legislative power is vested in the American Samoa Fono, which has two chambers. The House of Representatives has 21 members serving two-year terms, being 20 representatives popularly elected from various districts and one delegate from Swains Island elected in a public meeting. The Senate has 18 members, elected for four-year terms by and from the chiefs of the islands.
The judiciary of American Samoa is composed of the High Court of American Samoa, a District Court, and village courts. The High Court is led by a chief justice and an associate justice, appointed by the secretary of the interior. Other judges are appointed by the governor upon the recommendation of the chief justice and confirmed by the Senate.
## Elections
## International organization participation {#international_organization_participation}
- United Nations Economic and Social Commission for Asia and the Pacific (associate)
- Interpol (subbureau)
- International Olympic Committee
- Pacific Community
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Amplitude modulation
|
`{{Modulation techniques}}`{=mediawiki}
**Amplitude modulation** (**AM**) is a signal modulation technique used in electronic communication, most commonly for transmitting messages with a radio wave. In amplitude modulation, the instantaneous amplitude of the wave is varied in proportion to that of the message signal, such as an audio signal. This technique contrasts with angle modulation, in which either the frequency of the carrier wave is varied, as in frequency modulation, or its phase, as in phase modulation.
AM was the earliest modulation method used for transmitting audio in radio broadcasting. It was developed during the first quarter of the 20th century beginning with Roberto Landell de Moura and Reginald Fessenden\'s radiotelephone experiments in 1900. This original form of AM is sometimes called **double-sideband amplitude modulation** (**DSBAM**), because the standard method produces sidebands on either side of the carrier frequency. Single-sideband modulation uses bandpass filters to eliminate one of the sidebands and possibly the carrier signal, which improves the ratio of message power to total transmission power, reduces power handling requirements of line repeaters, and permits better bandwidth utilization of the transmission medium.
AM remains in use in many forms of communication in addition to AM broadcasting: shortwave radio, amateur radio, two-way radios, VHF aircraft radio, citizens band radio, and in computer modems in the form of quadrature amplitude modulation (QAM).
## Foundation
In electronics and telecommunications, modulation is the variation of a property of a continuous wave carrier signal according to an information-bearing signal, such as an audio signal which represents sound, or a video signal which represents images. In this sense, the carrier wave, which has a much higher frequency than the message signal, *carries* the information. At the receiving station, the message signal is extracted from the modulated carrier by demodulation.
In general form, a modulation process of a sinusoidal carrier wave may be described by the following equation:
$$m(t) = A(t) \cdot \cos(\omega t + \phi(t))\,$$.
*A(t)* represents the time-varying amplitude of the sinusoidal carrier wave and the cosine-term is the carrier at its angular frequency $\omega$, and the instantaneous phase deviation $\phi(t)$. This description directly provides the two major groups of modulation, amplitude modulation and angle modulation. In angle modulation, the term *A*(*t*) is constant and the second term of the equation has a functional relationship to the modulating message signal. Angle modulation provides two methods of modulation, frequency modulation and phase modulation.
In amplitude modulation, the angle term is held constant and the first term, *A*(*t*), of the equation has a functional relationship to the modulating message signal.
The modulating message signal may be analog in nature, or it may be a digital signal, in which case the technique is generally called amplitude-shift keying.
For example, in AM radio communication, a continuous wave radio-frequency signal has its amplitude modulated by an audio waveform before transmission. The message signal determines the *envelope* of the transmitted waveform. In the frequency domain, amplitude modulation produces a signal with power concentrated at the carrier frequency and two adjacent sidebands. Each sideband is equal in bandwidth to that of the modulating signal, and is a mirror image of the other. Standard AM is thus sometimes called \"double-sideband amplitude modulation\" (DSBAM).
A disadvantage of all amplitude modulation techniques, not only standard AM, is that the receiver amplifies and detects noise and electromagnetic interference in equal proportion to the signal. Increasing the received signal-to-noise ratio, say, by a factor of 10 (a 10 decibel improvement), thus would require increasing the transmitter power by a factor of 10. This is in contrast to frequency modulation (FM) and digital radio where the effect of such noise following demodulation is strongly reduced so long as the received signal is well above the threshold for reception. For this reason AM broadcast is not favored for music and high fidelity broadcasting, but rather for voice communications and broadcasts (sports, news, talk radio etc.).
AM is inefficient in power usage, as at least two-thirds of the transmitting power is concentrated in the carrier signal. The carrier signal contains none of the transmitted information (voice, video, data, etc.). However, its presence provides a simple means of demodulation using envelope detection, providing a frequency and phase reference for extracting the message signal from the sidebands. In some modulation systems based on AM, a lower transmitter power is required through partial or total elimination of the carrier component, however receivers for these signals are more complex because they must provide a precise carrier frequency reference signal (usually as shifted to the intermediate frequency) from a greatly reduced \"pilot\" carrier (in reduced-carrier transmission or DSB-RC) to use in the demodulation process. Even with the carrier eliminated in double-sideband suppressed-carrier transmission, carrier regeneration is possible using a Costas phase-locked loop. This does not work for single-sideband suppressed-carrier transmission (SSB-SC), leading to the characteristic \"Donald Duck\" sound from such receivers when slightly detuned. Single-sideband AM is nevertheless used widely in amateur radio and other voice communications because it has power and bandwidth efficiency (cutting the RF bandwidth in half compared to standard AM). On the other hand, in medium wave and short wave broadcasting, standard AM with the full carrier allows for reception using inexpensive receivers. The broadcaster absorbs the extra power cost to greatly increase potential audience.
### Shift keying {#shift_keying}
A simple form of digital amplitude modulation which can be used for transmitting binary data is on--off keying, the simplest form of amplitude-shift keying, in which ones and zeros are represented by the presence or absence of a carrier. On--off keying is likewise used by radio amateurs to transmit Morse code where it is known as continuous wave (CW) operation, even though the transmission is not strictly \"continuous\". A more complex form of AM, quadrature amplitude modulation is now more commonly used with digital data, while making more efficient use of the available bandwidth.
### Analog telephony {#analog_telephony}
A simple form of amplitude modulation is the transmission of speech signals from a traditional analog telephone set using a common battery local loop. The direct current provided by the central office battery is a carrier with a frequency of 0 Hz. It is modulated by a microphone (*transmitter*) in the telephone set according to the acoustic signal from the speaker. The result is a varying amplitude direct current, whose AC-component is the speech signal extracted at the central office for transmission to another subscriber.
### Amplitude reference {#amplitude_reference}
An additional function provided by the carrier in standard AM, but which is lost in either single or double-sideband suppressed-carrier transmission, is that it provides an amplitude reference. In the receiver, the automatic gain control (AGC) responds to the carrier so that the reproduced audio level stays in a fixed proportion to the original modulation. On the other hand, with suppressed-carrier transmissions there is *no* transmitted power during pauses in the modulation, so the AGC must respond to peaks of the transmitted power during peaks in the modulation. This typically involves a so-called *fast attack, slow decay* circuit which holds the AGC level for a second or more following such peaks, in between syllables or short pauses in the program. This is very acceptable for communications radios, where compression of the audio aids intelligibility. However, it is absolutely undesired for music or normal broadcast programming, where a faithful reproduction of the original program, including its varying modulation levels, is expected.
## ITU type designations {#itu_type_designations}
In 1982, the International Telecommunication Union (ITU) designated the types of amplitude modulation:
Designation Description
------------- -----------------------------------------------------------------------------------
A3E double-sideband a full-carrier -- the basic amplitude modulation scheme
R3E single-sideband reduced-carrier
H3E single-sideband full-carrier
J3E single-sideband suppressed-carrier
B8E independent-sideband emission
C3F vestigial-sideband
Lincompex linked compressor and expander (a submode of any of the above ITU Emission Modes)
## History
Amplitude modulation was used in experiments of multiplex telegraph and telephone transmission in the late 1800s. However, the practical development of this technology is identified with the period between 1900 and 1920 of radiotelephone transmission, that is, the effort to send audio signals by radio waves. The first radio transmitters, called spark gap transmitters, transmitted information by wireless telegraphy, using pulses of the carrier wave to spell out text messages in Morse code. They could not transmit audio because the carrier consisted of strings of damped waves, pulses of radio waves that declined to zero, and sounded like a buzz in receivers. In effect they were already amplitude modulated.
### Continuous waves {#continuous_waves}
The first AM transmission was made by Canadian-born American researcher Reginald Fessenden on December 23, 1900 using a spark gap transmitter with a specially designed high frequency 10 kHz interrupter, over a distance of 1 mi at Cobb Island, Maryland, US. His first transmitted words were, \"Hello. One, two, three, four. Is it snowing where you are, Mr. Thiessen?\". Though his words were \"perfectly intelligible\", the spark created a loud and unpleasant noise.
Fessenden was a significant figure in the development of AM radio. He was one of the first researchers to realize, from experiments like the above, that the existing technology for producing radio waves, the spark transmitter, was not usable for amplitude modulation, and that a new kind of transmitter, one that produced sinusoidal *continuous waves*, was needed. This was a radical idea at the time, because experts believed the impulsive spark was necessary to produce radio frequency waves, and Fessenden was ridiculed. He invented and helped develop one of the first continuous wave transmitters -- the Alexanderson alternator, with which he made what is considered the first AM public entertainment broadcast on Christmas Eve, 1906. He also discovered the principle on which AM is based, heterodyning, and invented one of the first detectors able to rectify and receive AM, the electrolytic detector or \"liquid baretter\", in 1902. Other radio detectors invented for wireless telegraphy, such as the Fleming valve (1904) and the crystal detector (1906) also proved able to rectify AM signals, so the technological hurdle was generating AM waves; receiving them was not a problem.
### Early technologies {#early_technologies}
Early experiments in AM radio transmission, conducted by Fessenden, Valdemar Poulsen, Ernst Ruhmer, Quirino Majorana, Charles Herrold, and Lee de Forest, were hampered by the lack of a technology for amplification. The first practical continuous wave AM transmitters were based on either the huge, expensive Alexanderson alternator, developed 1906--1910, or versions of the Poulsen arc transmitter (arc converter), invented in 1903. The modifications necessary to transmit AM were clumsy and resulted in very low quality audio. Modulation was usually accomplished by a carbon microphone inserted directly in the antenna or ground wire; its varying resistance varied the current to the antenna. The limited power handling ability of the microphone severely limited the power of the first radiotelephones; many of the microphones were water-cooled.
### Vacuum tubes {#vacuum_tubes}
The 1912 discovery of the amplifying ability of the Audion tube, invented in 1906 by Lee de Forest, solved these problems. The vacuum tube feedback oscillator, invented in 1912 by Edwin Armstrong and Alexander Meissner, was a cheap source of continuous waves and could be easily modulated to make an AM transmitter. Modulation did not have to be done at the output but could be applied to the signal before the final amplifier tube, so the microphone or other audio source didn\'t have to modulate a high-power radio signal. Wartime research greatly advanced the art of AM modulation, and after the war the availability of cheap tubes sparked a great increase in the number of radio stations experimenting with AM transmission of news or music. The vacuum tube was responsible for the rise of AM broadcasting around 1920, the first electronic mass communication medium. Amplitude modulation was virtually the only type used for radio broadcasting until FM broadcasting began after World War II.
At the same time as AM radio began, telephone companies such as AT&T were developing the other large application for AM: sending multiple telephone calls through a single wire by modulating them on separate carrier frequencies, called *frequency division multiplexing*.
### Single-sideband {#single_sideband}
In 1915, John Renshaw Carson formulated the first mathematical description of amplitude modulation, showing that a signal and carrier frequency combined in a nonlinear device creates a sideband on both sides of the carrier frequency. Passing the modulated signal through another nonlinear device can extract the original baseband signal. His analysis also showed that only one sideband was necessary to transmit the audio signal, and Carson patented single-sideband modulation (SSB) on 1 December 1915. This advanced variant of amplitude modulation was adopted by AT&T for longwave transatlantic telephone service beginning 7 January 1927. After WW-II, it was developed for military aircraft communication.
## Analysis
The carrier wave (sine wave) of frequency *f~c~* and amplitude *A* is expressed by
$$c(t) = A \sin(2 \pi f_c t)\,$$.
The message signal, such as an audio signal that is used for modulating the carrier, is *m*(*t*), and has a frequency *f~m~*, much lower than *f~c~*:
$$m(t) = M \cos\left(2\pi f_m t + \phi\right)= Am \cos\left(2\pi f_m t + \phi\right)\,$$,
where *m* is the amplitude sensitivity, *M* is the amplitude of modulation. If *m* \< 1, *(1 + m(t)/A)* is always positive for undermodulation. If *m* \> 1 then overmodulation occurs and reconstruction of message signal from the transmitted signal would lead in loss of original signal. Amplitude modulation results when the carrier *c(t)* is multiplied by the positive quantity *(1 + m(t)/A)*:
$$\begin{align}
y(t) &= \left[1 + \frac{m(t)}{A}\right] c(t) \\
&= \left[1 + m \cos\left(2\pi f_m t + \phi\right)\right] A \sin\left(2\pi f_c t\right)
\end{align}$$
In this simple case *m* is identical to the modulation index, discussed below. With *m* = 0.5 the amplitude modulated signal *y*(*t*) thus corresponds to the top graph (labelled \"50% Modulation\") in figure 4.
Using prosthaphaeresis identities, *y*(*t*) can be shown to be the sum of three sine waves:
$$y(t) = A \sin(2\pi f_c t) + \frac{1}{2}Am\left[\sin\left(2\pi \left[f_c + f_m\right] t + \phi\right) + \sin\left(2\pi \left[f_c - f_m\right] t - \phi\right)\right].\,$$
Therefore, the modulated signal has three components: the carrier wave *c(t)* which is unchanged in frequency, and two sidebands with frequencies slightly above and below the carrier frequency *f~c~*.
## Spectrum
A useful modulation signal *m(t)* is usually more complex than a single sine wave, as treated above. However, by the principle of Fourier decomposition, *m(t)* can be expressed as the sum of a set of sine waves of various frequencies, amplitudes, and phases. Carrying out the multiplication of *1 + m(t)* with *c(t)* as above, the result consists of a sum of sine waves. Again, the carrier *c(t)* is present unchanged, but each frequency component of *m* at *f~i~* has two sidebands at frequencies *f~c~ + f~i~* and *f~c~ -- f~i~*. The collection of the former frequencies above the carrier frequency is known as the upper sideband, and those below constitute the lower sideband. The modulation *m(t)* may be considered to consist of an equal mix of positive and negative frequency components, as shown in the top of figure 2. One can view the sidebands as that modulation *m(t)* having simply been shifted in frequency by *f~c~* as depicted at the bottom right of figure 2.
The short-term spectrum of modulation, changing as it would for a human voice for instance, the frequency content (horizontal axis) may be plotted as a function of time (vertical axis), as in figure 3. It can again be seen that as the modulation frequency content varies, an upper sideband is generated according to those frequencies shifted *above* the carrier frequency, and the same content mirror-imaged in the lower sideband below the carrier frequency. At all times, the carrier itself remains constant, and of greater power than the total sideband power.
## Power and spectrum efficiency {#power_and_spectrum_efficiency}
The RF bandwidth of an AM transmission (refer to figure 2, but only considering positive frequencies) is twice the bandwidth of the modulating (or \"baseband\") signal, since the upper and lower sidebands around the carrier frequency each have a bandwidth as wide as the highest modulating frequency. Although the bandwidth of an AM signal is narrower than one using frequency modulation (FM), it is twice as wide as single-sideband techniques; it thus may be viewed as spectrally inefficient. Within a frequency band, only half as many transmissions (or \"channels\") can thus be accommodated. For this reason analog television employs a variant of single-sideband (known as vestigial sideband, somewhat of a compromise in terms of bandwidth) in order to reduce the required channel spacing.
Another improvement over standard AM is obtained through reduction or suppression of the carrier component of the modulated spectrum. In figure 2 this is the spike in between the sidebands; even with full (100%) sine wave modulation, the power in the carrier component is twice that in the sidebands, yet it carries no unique information. Thus there is a great advantage in efficiency in reducing or totally suppressing the carrier, either in conjunction with elimination of one sideband (single-sideband suppressed-carrier transmission) or with both sidebands remaining (double sideband suppressed carrier). While these suppressed carrier transmissions are efficient in terms of transmitter power, they require more sophisticated receivers employing synchronous detection and regeneration of the carrier frequency. For that reason, standard AM continues to be widely used, especially in broadcast transmission, to allow for the use of inexpensive receivers using envelope detection. Even (analog) television, with a (largely) suppressed lower sideband, includes sufficient carrier power for use of envelope detection. But for communications systems where both transmitters and receivers can be optimized, suppression of both one sideband and the carrier represent a net advantage and are frequently employed.
A technique used widely in broadcast AM transmitters is an application of the Hapburg carrier, first proposed in the 1930s but impractical with the technology then available. During periods of low modulation the carrier power would be reduced and would return to full power during periods of high modulation levels. This has the effect of reducing the overall power demand of the transmitter and is most effective on speech type programmes. Various trade names are used for its implementation by the transmitter manufacturers from the late 80\'s onwards.
## Modulation index {#modulation_index}
The AM modulation index is a measure based on the ratio of the modulation excursions of the RF signal to the level of the unmodulated carrier. It is thus defined as:
$$m = \frac{\mathrm{peak\ value\ of\ } m(t)}{A} = \frac{M}{A}$$
where $M\,$ and $A\,$ are the modulation amplitude and carrier amplitude, respectively; the modulation amplitude is the peak (positive or negative) change in the RF amplitude from its unmodulated value. Modulation index is normally expressed as a percentage, and may be displayed on a meter connected to an AM transmitter.
So if $m=0.5$, carrier amplitude varies by 50% above (and below) its unmodulated level, as is shown in the first waveform, below. For $m=1.0$, it varies by 100% as shown in the illustration below it. With 100% modulation the wave amplitude sometimes reaches zero, and this represents full modulation using standard AM and is often a target (in order to obtain the highest possible signal-to-noise ratio) but mustn\'t be exceeded. Increasing the modulating signal beyond that point, known as overmodulation, causes a standard AM modulator (see below) to fail, as the negative excursions of the wave envelope cannot become less than zero, resulting in distortion (\"clipping\") of the received modulation. Transmitters typically incorporate a limiter circuit to avoid overmodulation, and/or a compressor circuit (especially for voice communications) in order to still approach 100% modulation for maximum intelligibility above the noise. Such circuits are sometimes referred to as a vogad.
However it is possible to talk about a modulation index exceeding 100%, without introducing distortion, in the case of double-sideband reduced-carrier transmission. In that case, negative excursions beyond zero entail a reversal of the carrier phase, as shown in the third waveform below. This cannot be produced using the efficient high-level (output stage) modulation techniques (see below) which are widely used especially in high power broadcast transmitters. Rather, a special modulator produces such a waveform at a low level followed by a linear amplifier. What\'s more, a standard AM receiver using an envelope detector is incapable of properly demodulating such a signal. Rather, synchronous detection is required. Thus double-sideband transmission is generally *not* referred to as \"AM\" even though it generates an identical RF waveform as standard AM as long as the modulation index is below 100%. Such systems more often attempt a radical reduction of the carrier level compared to the sidebands (where the useful information is present) to the point of double-sideband suppressed-carrier transmission where the carrier is (ideally) reduced to zero. In all such cases the term \"modulation index\" loses its value as it refers to the ratio of the modulation amplitude to a rather small (or zero) remaining carrier amplitude.
## `{{anchor|AM modulation methods}}`{=mediawiki}Modulation methods {#modulation_methods}
Modulation circuit designs may be classified as low- or high-level (depending on whether they modulate in a low-power domain---followed by amplification for transmission---or in the high-power domain of the transmitted signal).
### Low-level generation {#low_level_generation}
In modern radio systems, modulated signals are generated via digital signal processing (DSP). With DSP many types of AM are possible with software control (including DSB with carrier, SSB suppressed-carrier and independent sideband, or ISB). Calculated digital samples are converted to voltages with a digital-to-analog converter, typically at a frequency less than the desired RF-output frequency. The analog signal must then be shifted in frequency and linearly amplified to the desired frequency and power level (linear amplification must be used to prevent modulation distortion). This low-level method for AM is used in many Amateur Radio transceivers.
AM may also be generated at a low level, using analog methods described in the next section.
### High-level generation {#high_level_generation}
High-power AM transmitters (such as those used for AM broadcasting) are based on high-efficiency class-D and class-E power amplifier stages, modulated by varying the supply voltage.
Older designs (for broadcast and amateur radio) also generate AM by controlling the gain of the transmitter\'s final amplifier (generally class-C, for efficiency). The following types are for vacuum tube transmitters (but similar options are available with transistors):
Plate modulation: In plate modulation, the plate voltage of the RF amplifier is modulated with the audio signal. The audio power requirement is 50 percent of the RF-carrier power.\
Heising (constant-current) modulation: RF amplifier plate voltage is fed through a choke (high-value inductor). The AM modulation tube plate is fed through the same inductor, so the modulator tube diverts current from the RF amplifier. The choke acts as a constant current source in the audio range. This system has a low power efficiency.\
Control grid modulation: The operating bias and gain of the final RF amplifier can be controlled by varying the voltage of the control grid. This method requires little audio power, but care must be taken to reduce distortion.\
Clamp tube (screen grid) modulation: The screen-grid bias may be controlled through a *clamp tube*, which reduces voltage according to the modulation signal. It is difficult to approach 100-percent modulation while maintaining low distortion with this system.\
Doherty modulation: One tube provides the power under carrier conditions and another operates only for positive modulation peaks. Overall efficiency is good, and distortion is low.\
Outphasing modulation: Two tubes are operated in parallel, but partially out of phase with each other. As they are differentially phase modulated their combined amplitude is greater or smaller. Efficiency is good and distortion low when properly adjusted.\
Pulse-width modulation (PWM) or pulse-duration modulation (PDM): A highly efficient high voltage power supply is applied to the tube plate. The output voltage of this supply is varied at an audio rate to follow the program. This system was pioneered by Hilmer Swanson and has a number of variations, all of which achieve high efficiency and sound quality.\
Digital methods: The Harris Corporation obtained a patent for synthesizing a modulated high-power carrier wave from a set of digitally selected low-power amplifiers, running in phase at the same carrier frequency. The input signal is sampled by a conventional audio analog-to-digital converter (ADC), and fed to a digital exciter, which modulates overall transmitter output power by switching a series of low-power solid-state RF amplifiers on and off. The combined output drives the antenna system.
## `{{anchor|AM demodulation methods}}`{=mediawiki}Demodulation methods {#demodulation_methods}
The simplest form of AM demodulator consists of a diode which is configured to act as envelope detector. Another type of demodulator, the product detector, can provide better-quality demodulation with additional circuit complexity.
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Assembly line
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An **assembly line**, often called *progressive assembly*, is a manufacturing process where the unfinished product moves in a direct line from workstation to workstation, with parts added in sequence until the final product is completed. By mechanically moving parts to workstations and transferring the unfinished product from one workstation to another, a finished product can be assembled faster and with less labor than having workers carry parts to a stationary product.
Assembly lines are common methods of assembling complex items such as automobiles and other transportation equipment, household appliances and electronic goods.
Workers in charge of the works of assembly line are called **assemblers**.
## Concepts
Assembly lines are designed for the sequential organization of workers, tools or machines, and parts. The motion of workers is minimized to the extent possible. All parts or assemblies are handled either by conveyors or motorized vehicles such as forklifts, or gravity, with no manual trucking. Heavy lifting is done by machines such as overhead cranes or forklifts. Each worker typically performs one simple operation unless job rotation strategies are applied.
According to Henry Ford:
Designing assembly lines is a well-established mathematical challenge, referred to as an assembly line balancing problem. In the simple assembly line balancing problem the aim is to assign a set of tasks that need to be performed on the workpiece to a sequence of workstations. Each task requires a given task duration for completion. The assignment of tasks to stations is typically limited by two constraints: (1) a precedence graph which indicates what other tasks need to be completed before a particular task can be initiated (e.g. not putting in a screw before drilling the hole) and (2) a cycle time which restricts the sum of task processing times which can be completed at each workstation before the work-piece is moved to the next station by the conveyor belt. Major planning problems for operating assembly lines include supply chain integration, inventory control and production scheduling.
## Simple example {#simple_example}
Consider the assembly of a car: assume that certain steps in the assembly line are to install the engine, install the hood, and install the wheels (in that order, with arbitrary interstitial steps); only one of these steps can be done at a time. In traditional production, only one car would be assembled at a time. If engine installation takes 20 minutes, hood installation takes five minutes, and wheels installation takes 10 minutes, then a car can be produced every 35 minutes.
In an assembly line, car assembly is split between several stations, all working simultaneously. When a station is finished with a car, it passes it on to the next. By having three stations, three cars can be operated on at the same time, each at a different stage of assembly.
After finishing its work on the first car, the engine installation crew can begin working on the second car. While the engine installation crew works on the second car, the first car can be moved to the hood station and fitted with a hood, then to the wheels station and be fitted with wheels. After the engine has been installed on the second car, the second car moves to the hood assembly. At the same time, the third car moves to the engine assembly. When the third car\'s engine has been mounted, it then can be moved to the hood station; meanwhile, subsequent cars (if any) can be moved to the engine installation station.
Assuming no loss of time when moving a car from one station to another, the longest stage on the assembly line determines the throughput (20 minutes for the engine installation) so a car can be produced every 20 minutes, once the first car taking 35 minutes has been produced.
## History
Before the Industrial Revolution, most manufactured products were made individually by hand. A single craftsman or team of craftsmen would create each part of a product. They would use their skills and tools such as files and knives to create the individual parts. They would then assemble them into the final product, making cut-and-try changes in the parts until they fit and could work together (craft production).
Division of labor was practiced by Ancient Greeks, Chinese and other ancient civilizations. In Ancient Greece it was discussed by Plato and Xenophon. Adam Smith discussed the division of labour in the manufacture of pins at length in his book *The Wealth of Nations* (published in 1776).
The Venetian Arsenal, dating to about 1104, operated similar to a production line. Ships moved down a canal and were fitted by the various shops they passed. At the peak of its efficiency in the early 16th century, the Arsenal employed some 16,000 people who could apparently produce nearly one ship each day and could fit out, arm, and provision a newly built galley with standardized parts on an assembly-line basis. Although the Arsenal lasted until the early Industrial Revolution, production line methods did not become common even then.
### Industrial Revolution {#industrial_revolution}
The Industrial Revolution led to a proliferation of manufacturing and invention. Many industries, notably textiles, firearms, clocks and watches, horse-drawn vehicles, railway locomotives, sewing machines, and bicycles, saw expeditious improvement in materials handling, machining, and assembly during the 19th century, although modern concepts such as industrial engineering and logistics had not yet been named.
The automatic flour mill built by Oliver Evans in 1785 was called the beginning of modern bulk material handling by Roe (1916). Evans\'s mill used a leather belt bucket elevator, screw conveyors, canvas belt conveyors, and other mechanical devices to completely automate the process of making flour. The innovation spread to other mills and breweries.
Probably the earliest industrial example of a linear and continuous assembly process is the Portsmouth Block Mills, built between 1801 and 1803. Marc Isambard Brunel (father of Isambard Kingdom Brunel), with the help of Henry Maudslay and others, designed 22 types of machine tools to make the parts for the rigging blocks used by the Royal Navy. This factory was so successful that it remained in use until the 1960s, with the workshop still visible at HM Dockyard in Portsmouth, and still containing some of the original machinery.
One of the earliest examples of an almost modern factory layout, designed for easy material handling, was the Bridgewater Foundry. The factory grounds were bordered by the Bridgewater Canal and the Liverpool and Manchester Railway. The buildings were arranged in a line with a railway for carrying the work going through the buildings. Cranes were used for lifting the heavy work, which sometimes weighed in the tens of tons. The work passed sequentially through to erection of framework and final assembly.
The first flow assembly line was initiated at the factory of Richard Garrett & Sons, Leiston Works in Leiston in the English county of Suffolk for the manufacture of portable steam engines. The assembly line area was called \'The Long Shop\' on account of its length and was fully operational by early 1853. The boiler was brought up from the foundry and put at the start of the line, and as it progressed through the building it would stop at various stages where new parts would be added. From the upper level, where other parts were made, the lighter parts would be lowered over a balcony and then fixed onto the machine on the ground level. When the machine reached the end of the shop, it would be completed.
### Interchangeable parts {#interchangeable_parts}
During the early 19th century, the development of machine tools such as the screw-cutting lathe, metal planer, and milling machine, and of toolpath control via jigs and fixtures, provided the prerequisites for the modern assembly line by making interchangeable parts a practical reality.
### Late 19th-century steam and electric conveyors {#late_19th_century_steam_and_electric_conveyors}
Steam-powered conveyor lifts began being used for loading and unloading ships some time in the last quarter of the 19th century. Hounshell (1984) shows a c. 1885 sketch of an electric-powered conveyor moving cans through a filling line in a canning factory.
The meatpacking industry of Chicago is believed to be one of the first industrial assembly lines (or disassembly lines) to be utilized in the United States starting in 1867. Workers would stand at fixed stations and a pulley system would bring the meat to each worker and they would complete one task. Henry Ford and others have written about the influence of this slaughterhouse practice on the later developments at Ford Motor Company.
### 20th century {#th_century}
thumb\|thumbtime=2\|Ford Model T assembly line c. 1919 thumb\|thumbtime=6\|start=6\|end=47\|Ford Model T assembly line c. 1924 thumb\|thumbtime=6\|Ford assembly line c. 1930 thumb\|thumbtime=6\|Ford assembly line c. 1947 According to Domm, the implementation of mass production of an automobile via an assembly line may be credited to Ransom Olds, who used it to build the first mass-produced automobile, the Oldsmobile Curved Dash. Olds patented the assembly line concept, which he put to work in his Olds Motor Vehicle Company factory in 1901.
At Ford Motor Company, the assembly line was introduced by William \"Pa\" Klann upon his return from visiting Swift & Company\'s slaughterhouse in Chicago and viewing what was referred to as the \"disassembly line\", where carcasses were butchered as they moved along a conveyor. The efficiency of one person removing the same piece over and over without moving to another station caught his attention. He reported the idea to Peter E. Martin, soon to be head of Ford production, who was doubtful at the time but encouraged him to proceed. Others at Ford have claimed to have put the idea forth to Henry Ford, but Pa Klann\'s slaughterhouse revelation is well documented in the archives at the Henry Ford Museum and elsewhere, making him an important contributor to the modern automated assembly line concept. Ford was appreciative, having visited the highly automated 40-acre Sears mail order handling facility around 1906. At Ford, the process was an evolution by trial and error of a team consisting primarily of Peter E. Martin, the factory superintendent; Charles E. Sorensen, Martin\'s assistant; Clarence W. Avery; C. Harold Wills, draftsman and toolmaker; Charles Ebender; and József Galamb. Some of the groundwork for such development had recently been laid by the intelligent layout of machine tool placement that Walter Flanders had been doing at Ford up to 1908.
The moving assembly line was developed for the Ford Model T and began operation on October 7, 1913, at the Highland Park Ford Plant, and continued to evolve after that, using time and motion study. The assembly line, driven by conveyor belts, reduced production time for a Model T to just 93 minutes by dividing the process into 45 steps. Producing cars quicker than paint of the day could dry, it had an immense influence on the world.
In 1922, Ford (through his ghostwriter Crowther) said of his 1913 assembly line:
Charles E. Sorensen, in his 1956 memoir *My Forty Years with Ford*, presented a different version of development that was not so much about individual \"inventors\" as a gradual, logical development of industrial engineering:
As a result of these developments in method, Ford\'s cars came off the line in three-minute intervals or six feet per minute. This was much faster than previous methods, increasing production by eight to one (requiring 12.5 man-hours before, 1 hour 33 minutes after), while using less manpower. It was so successful, paint became a bottleneck. Only japan black would dry fast enough, forcing the company to drop the variety of colours available before 1914, until fast-drying Duco lacquer was developed in 1926.
The assembly line technique was an integral part of the diffusion of the automobile into American society. Decreased costs of production allowed the cost of the Model T to fall within the budget of the American middle class. In 1908, the price of a Model T was around \$825, and by 1912 it had decreased to around \$575. This price reduction is comparable to a reduction from \$15,000 to \$10,000 in dollar terms from the year 2000. In 1914, an assembly line worker could buy a Model T with four months\' pay.
Ford\'s complex safety procedures---especially assigning each worker to a specific location instead of allowing them to roam about---dramatically reduced the rate of injury. The combination of high wages and high efficiency is called \"Fordism\", and was copied by most major industries. The efficiency gains from the assembly line also coincided with the take-off of the United States. The assembly line forced workers to work at a certain pace with very repetitive motions which led to more output per worker while other countries were using less productive methods.
In the automotive industry, its success was dominating, and quickly spread worldwide. Ford France and Ford Britain in 1911, Ford Denmark 1923, Ford Germany and Ford Japan 1925; in 1919, Vulcan (Southport, Lancashire) was the first native European manufacturer to adopt it. Soon, companies had to have assembly lines, or risk going broke by not being able to compete; by 1930, 250 companies which did not had disappeared.
The massive demand for military hardware in World War II prompted assembly-line techniques in shipbuilding and aircraft production. Thousands of Liberty ships were built making extensive use of prefabrication, enabling ship assembly to be completed in weeks or even days. After having produced fewer than 3,000 planes for the United States Military in 1939, American aircraft manufacturers built over 300,000 planes in World War II. Vultee pioneered the use of the powered assembly line for aircraft manufacturing. Other companies quickly followed. As William S. Knudsen (having worked at Ford, GM and the National Defense Advisory Commission) observed, \"We won because we smothered the enemy in an avalanche of production, the like of which he had never seen, nor dreamed possible.\"
## Improved working conditions {#improved_working_conditions}
In his 1922 autobiography, Henry Ford mentions several benefits of the assembly line including:
- Workers do not do any heavy lifting.
- No stooping or bending over.
- No special training was required.
- There are jobs that almost anyone can do.
- Provided employment to immigrants.
The gains in productivity allowed Ford to increase worker pay from \$1.50 per day to \$5.00 per day once employees reached three years of service on the assembly line. Ford continued on to reduce the hourly work week while continuously lowering the Model T price. These goals appear altruistic; however, it has been argued that they were implemented by Ford in order to reduce high employee turnover: when the assembly line was introduced in 1913, it was discovered that \"every time the company wanted to add 100 men to its factory personnel, it was necessary to hire 963\" in order to counteract the natural distaste the assembly line seems to have inspired.
## Sociological problems {#sociological_problems}
Sociological work has explored the social alienation and boredom that many workers feel because of the repetition of doing the same specialized task all day long.
Karl Marx expressed in his theory of alienation the belief that, in order to achieve job satisfaction, workers need to see themselves in the objects they have created, that products should be \"mirrors in which workers see their reflected essential nature\". Marx viewed labour as a chance for people to externalize facets of their personalities. Marxists argue that performing repetitive, specialized tasks causes a feeling of disconnection between what a worker does all day, who they really are, and what they would ideally be able to contribute to society. Furthermore, Marx views these specialised jobs as insecure, since the worker is expendable as soon as costs rise and technology can replace more expensive human labour.
Since workers have to stand in the same place for hours and repeat the same motion hundreds of times per day, repetitive stress injuries are a possible pathology of occupational safety. Industrial noise also proved dangerous. When it was not too high, workers were often prohibited from talking. Charles Piaget, a skilled worker at the LIP factory, recalled that besides being prohibited from speaking, the semi-skilled workers had only 25 centimeters in which to move. Industrial ergonomics later tried to minimize physical trauma.
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Algebraic number
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In mathematics, an **algebraic number** is a number that is a root of a non-zero polynomial in one variable with integer (or, equivalently, rational) coefficients. For example, the golden ratio $(1 + \sqrt{5})/2$ is an algebraic number, because it is a root of the polynomial $X^2 - X - 1$, i.e., a solution of the equation $x^2 - x - 1 = 0$, and the complex number $1 + i$ is algebraic as a root of $X^4 + 4$. Algebraic numbers include all integers, rational numbers, and *n*-th roots of integers.
Algebraic complex numbers are closed under addition, subtraction, multiplication and division, and hence form a field, denoted $\overline{\Q}$. The set of algebraic real numbers $\overline{\Q} \cap \R$ is also a field.
Numbers which are not algebraic are called transcendental and include `{{pi}}`{=mediawiki} and `{{mvar|[[e (mathematical constant)|e]]}}`{=mediawiki}. There are countably many algebraic numbers, hence almost all real (or complex) numbers (in the sense of Lebesgue measure) are transcendental.
## Examples
- All rational numbers are algebraic. Any rational number, expressed as the quotient of an integer `{{mvar|a}}`{=mediawiki} and a (non-zero) natural number `{{mvar|b}}`{=mediawiki}, satisfies the above definition, because `{{math|''x'' {{=}}`{=mediawiki} `{{sfrac|''a''|''b''}}`{=mediawiki}}} is the root of a non-zero polynomial, namely `{{math|''bx'' − ''a''}}`{=mediawiki}.
- Quadratic irrational numbers, irrational solutions of a quadratic polynomial `{{math|''ax''{{sup|2}} + ''bx'' + ''c''}}`{=mediawiki} with integer coefficients `{{mvar|a}}`{=mediawiki}, `{{mvar|b}}`{=mediawiki}, and `{{mvar|c}}`{=mediawiki}, are algebraic numbers. If the quadratic polynomial is monic (`{{math|''a'' {{=}}`{=mediawiki} 1}}), the roots are further qualified as quadratic integers.
- Gaussian integers, complex numbers `{{math|''a'' + ''bi''}}`{=mediawiki} for which both `{{mvar|a}}`{=mediawiki} and `{{mvar|b}}`{=mediawiki} are integers, are also quadratic integers. This is because `{{math|''a'' + ''bi''}}`{=mediawiki} and `{{math|''a'' − ''bi''}}`{=mediawiki} are the two roots of the quadratic `{{math|''x''{{sup|2}} − 2''ax'' + ''a''{{sup|2}} + ''b''{{sup|2}}}}`{=mediawiki}.
- A constructible number can be constructed from a given unit length using a straightedge and compass. It includes all quadratic irrational roots, all rational numbers, and all numbers that can be formed from these using the basic arithmetic operations and the extraction of square roots. (By designating cardinal directions for +1, −1, +`{{mvar|i}}`{=mediawiki}, and −`{{mvar|i}}`{=mediawiki}, complex numbers such as $3+i \sqrt{2}$ are considered constructible.)
- Any expression formed from algebraic numbers using any finite combination of the basic arithmetic operations and extraction of `{{mvar|n}}`{=mediawiki}th roots gives another algebraic number.
- Polynomial roots that cannot be expressed in terms of the basic arithmetic operations and extraction of `{{mvar|n}}`{=mediawiki}th roots (such as the roots of `{{math|''x''<sup>5</sup> − ''x'' + 1}}`{=mediawiki}). That happens with many but not all polynomials of degree 5 or higher.
- Values of trigonometric functions of rational multiples of `{{pi}}`{=mediawiki} (except when undefined): for example, `{{math|cos {{sfrac|{{math|π}}|7}}}}`{=mediawiki}, `{{math|cos {{sfrac|3{{math|π}}|7}}}}`{=mediawiki}, and `{{math|cos {{sfrac|5{{math|π}}|7}}}}`{=mediawiki} satisfy `{{math|8''x''<sup>3</sup> − 4''x''<sup>2</sup> − 4''x'' + 1 {{=}}`{=mediawiki} 0}}. This polynomial is irreducible over the rationals and so the three cosines are *conjugate* algebraic numbers. Likewise, `{{math|tan {{sfrac|3{{math|π}}|16}}}}`{=mediawiki}, `{{math|tan {{sfrac|7{{math|π}}|16}}}}`{=mediawiki}, `{{math|tan {{sfrac|11{{math|π}}|16}}}}`{=mediawiki}, and `{{math|tan {{sfrac|15{{math|π}}|16}}}}`{=mediawiki} satisfy the irreducible polynomial `{{math|''x''<sup>4</sup> − 4''x''<sup>3</sup> − 6''x''<sup>2</sup> + 4''x'' + 1 {{=}}`{=mediawiki} 0}}, and so are conjugate algebraic integers. This is the equivalent of angles which, when measured in degrees, have rational numbers.
- Some but not all irrational numbers are algebraic:
- The numbers $\sqrt{2}$ and $\frac{ \sqrt[3]{3} }{ 2 }$ are algebraic since they are roots of polynomials `{{math|''x''<sup>2</sup> − 2}}`{=mediawiki} and `{{math|8''x''<sup>3</sup> − 3}}`{=mediawiki}, respectively.
- The golden ratio `{{mvar|φ}}`{=mediawiki} is algebraic since it is a root of the polynomial `{{math|''x''<sup>2</sup> − ''x'' − 1}}`{=mediawiki}.
- The numbers `{{pi}}`{=mediawiki} and e are not algebraic numbers (see the Lindemann--Weierstrass theorem).
## Properties
- If a polynomial with rational coefficients is multiplied through by the least common denominator, the resulting polynomial with integer coefficients has the same roots. This shows that an algebraic number can be equivalently defined as a root of a polynomial with either integer or rational coefficients.
- Given an algebraic number, there is a unique monic polynomial with rational coefficients of least degree that has the number as a root. This polynomial is called its minimal polynomial. If its minimal polynomial has degree `{{mvar|n}}`{=mediawiki}, then the algebraic number is said to be of **degree `{{mvar|n}}`{=mediawiki}**. For example, all rational numbers have degree 1, and an algebraic number of degree 2 is a quadratic irrational.
- The algebraic numbers are dense in the reals. This follows from the fact they contain the rational numbers, which are dense in the reals themselves.
- The set of algebraic numbers is countable, and therefore its Lebesgue measure as a subset of the complex numbers is 0 (essentially, the algebraic numbers take up no space in the complex numbers). That is to say, \"almost all\" real and complex numbers are transcendental.
- All algebraic numbers are computable and therefore definable and arithmetical.
- For real numbers `{{math|''a''}}`{=mediawiki} and `{{math|''b''}}`{=mediawiki}, the complex number `{{math|''a'' + ''bi''}}`{=mediawiki} is algebraic if and only if both `{{math|''a''}}`{=mediawiki} and `{{math|''b''}}`{=mediawiki} are algebraic.
### Degree of simple extensions of the rationals as a criterion to algebraicity {#degree_of_simple_extensions_of_the_rationals_as_a_criterion_to_algebraicity}
For any `{{math|α}}`{=mediawiki}, the simple extension of the rationals by `{{math|α}}`{=mediawiki}, denoted by $\Q(\alpha)$ (whose elements are the $f(\alpha)$ for $f$ a rational function with rational coefficients which is defined at $\alpha$), is of finite degree if and only if `{{math|α}}`{=mediawiki} is an algebraic number.
The condition of finite degree means that there is a finite set $\{a_i | 1\le i\le k\}$ in $\Q(\alpha)$ such that $\Q(\alpha) = \sum_{i=1}^k a_i \Q$; that is, every member in $\Q(\alpha)$ can be written as $\sum_{i=1}^k a_i q_i$ for some rational numbers $\{q_i | 1\le i\le k\}$ (note that the set $\{a_i\}$ is fixed).
Indeed, since the $a_i-s$ are themselves members of $\Q(\alpha)$, each can be expressed as sums of products of rational numbers and powers of `{{math|α}}`{=mediawiki}, and therefore this condition is equivalent to the requirement that for some finite $n$, $\Q(\alpha) = \{\sum_{i=-n}^n \alpha^{i} q_i | q_i\in \Q\}$.
The latter condition is equivalent to $\alpha^{n+1}$, itself a member of $\Q(\alpha)$, being expressible as $\sum_{i=-n}^n \alpha^i q_i$ for some rationals $\{q_i\}$, so $\alpha^{2n+1} = \sum_{i=0}^{2n} \alpha^i q_{i-n}$ or, equivalently, `{{math|α}}`{=mediawiki} is a root of $x^{2n+1}-\sum_{i=0}^{2n} x^i q_{i-n}$; that is, an algebraic number with a minimal polynomial of degree not larger than $2n+1$.
It can similarly be proven that for any finite set of algebraic numbers $\alpha_1$, $\alpha_2$\... $\alpha_n$, the field extension $\Q(\alpha_1, \alpha_2, ... \alpha_n)$ has a finite degree.
## Field
The sum, difference, product, and quotient (if the denominator is nonzero) of two algebraic numbers is again algebraic:
For any two algebraic numbers `{{math|α}}`{=mediawiki}, `{{math|β}}`{=mediawiki}, this follows directly from the fact that the simple extension $\Q(\gamma)$, for $\gamma$ being either $\alpha+\beta$, $\alpha-\beta$, $\alpha\beta$ or (for $\beta\ne 0$) $\alpha/\beta$, is a linear subspace of the finite-degree field extension $\Q(\alpha,\beta)$, and therefore has a finite degree itself, from which it follows (as shown above) that $\gamma$ is algebraic.
An alternative way of showing this is constructively, by using the resultant.
Algebraic numbers thus form a field $\overline{\mathbb{Q}}$ (sometimes denoted by $\mathbb A$, but that usually denotes the adele ring).
### Algebraic closure {#algebraic_closure}
Every root of a polynomial equation whose coefficients are *algebraic numbers* is again algebraic. That can be rephrased by saying that the field of algebraic numbers is algebraically closed. In fact, it is the smallest algebraically closed field containing the rationals and so it is called the algebraic closure of the rationals.
That the field of algebraic numbers is algebraically closed can be proven as follows: Let `{{math|β}}`{=mediawiki} be a root of a polynomial $\alpha_0 + \alpha_1 x + \alpha_2 x^2 ... +\alpha_n x^n$ with coefficients that are algebraic numbers $\alpha_0$, $\alpha_1$, $\alpha_2$\... $\alpha_n$. The field extension $\Q^\prime \equiv \Q(\alpha_1, \alpha_2, ... \alpha_n)$ then has a finite degree with respect to $\Q$. The simple extension $\Q^\prime(\beta)$ then has a finite degree with respect to $\Q^\prime$ (since all powers of `{{math|β}}`{=mediawiki} can be expressed by powers of up to $\beta^{n-1}$). Therefore, $\Q^\prime(\beta) = \Q(\beta, \alpha_1, \alpha_2, ... \alpha_n)$ also has a finite degree with respect to $\Q$. Since $\Q(\beta)$ is a linear subspace of $\Q^\prime(\beta)$, it must also have a finite degree with respect to $\Q$, so `{{math|β}}`{=mediawiki} must be an algebraic number.
## Related fields {#related_fields}
### Numbers defined by radicals {#numbers_defined_by_radicals}
Any number that can be obtained from the integers using a finite number of additions, subtractions, multiplications, divisions, and taking (possibly complex) `{{mvar|n}}`{=mediawiki}th roots where `{{mvar|n}}`{=mediawiki} is a positive integer are algebraic. The converse, however, is not true: there are algebraic numbers that cannot be obtained in this manner. These numbers are roots of polynomials of degree 5 or higher, a result of Galois theory (see Quintic equations and the Abel--Ruffini theorem). For example, the equation:
$$x^5-x-1=0$$
has a unique real root, ≈ 1.1673, that cannot be expressed in terms of only radicals and arithmetic operations.
### Closed-form number {#closed_form_number}
Algebraic numbers are all numbers that can be defined explicitly or implicitly in terms of polynomials, starting from the rational numbers. One may generalize this to \"closed-form numbers\", which may be defined in various ways. Most broadly, all numbers that can be defined explicitly or implicitly in terms of polynomials, exponentials, and logarithms are called \"elementary numbers\", and these include the algebraic numbers, plus some transcendental numbers. Most narrowly, one may consider numbers *explicitly* defined in terms of polynomials, exponentials, and logarithms -- this does not include all algebraic numbers, but does include some simple transcendental numbers such as `{{mvar|e}}`{=mediawiki} or ln 2.
## Algebraic integers {#algebraic_integers}
*Main article: Algebraic integer* An *algebraic integer* is an algebraic number that is a root of a polynomial with integer coefficients with leading coefficient 1 (a monic polynomial). Examples of algebraic integers are $5 + 13 \sqrt{2},$ $2 - 6i,$ and $\frac{1}{2}(1+i\sqrt{3}).$ Therefore, the algebraic integers constitute a proper superset of the integers, as the latter are the roots of monic polynomials `{{math|''x'' − ''k''}}`{=mediawiki} for all $k \in \mathbb{Z}$. In this sense, algebraic integers are to algebraic numbers what integers are to rational numbers.
The sum, difference and product of algebraic integers are again algebraic integers, which means that the algebraic integers form a ring. The name *algebraic integer* comes from the fact that the only rational numbers that are algebraic integers are the integers, and because the algebraic integers in any number field are in many ways analogous to the integers. If `{{math|''K''}}`{=mediawiki} is a number field, its ring of integers is the subring of algebraic integers in `{{math|''K''}}`{=mediawiki}, and is frequently denoted as `{{math|''O<sub>K</sub>''}}`{=mediawiki}. These are the prototypical examples of Dedekind domains.
## Special classes {#special_classes}
- Algebraic solution
- Gaussian integer
- Eisenstein integer
- Quadratic irrational number
- Fundamental unit
- Root of unity
- Gaussian period
- Pisot--Vijayaraghavan number
- Salem number
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1,166 |
Afro Celt Sound System
|
**Afro Celt Sound System** are a European and African group who fuse electronic music with traditional Gaelic and West African music. Afro Celt Sound System was formed in 1995 by producer-guitarist Simon Emmerson, and feature a wide range of guest artists. In 2003, they temporarily changed their name to **Afrocelts** before reverting to their original name.
Their albums have been released through Peter Gabriel\'s Real World Records, and they have frequently performed at WOMAD festivals worldwide. Their sales on the label are exceeded only by Gabriel himself. Their recording contract with Real World was for five albums, of which *Volume 5: Anatomic* was the last.
After a number of festival dates in 2007, the band went on hiatus. In 2010, they regrouped to play a number of shows (including a return to WOMAD), and released a remastered retrospective titled *Capture*.
On 20 May 2014, Afro Celt Sound System announced the release of the album *Born*. In January 2016, a posting on their website revealed that due to a dispute with Emmerson, who announced his departure from the band in 2015, there were two active versions of the band, one led by Emmerson and another with a separate line-up headed by James McNally and Martin Russell. Emmerson\'s version of the band released the album *The Source* in 2016. The dispute ended on 21 December 2016, with an announcement on social media.
The band released their seventh studio album, *Flight*, on 23 November 2018.
## Formation
The inspiration behind the project dates back to 1991, when Simon Emmerson, a Grammy Award-nominated British producer and guitarist, collaborated with Afro-pop star Baaba Maal. While making an album with Maal in Senegal, Emmerson was struck by the similarity between one African melody and a traditional Irish air. Back in London, Irish musician Davy Spillane told Emmerson about a belief that nomadic Celts lived in Africa or India before they migrated to Western Europe. Whether or not the theory was true, Emmerson was intrigued by the two regions\' musical affinities.
In an experiment that would prove successful, Emmerson brought two members of Baaba Maal\'s band together with traditional Irish musicians to see what kind of music the two groups would create. Adding a dash of modern sound, Emmerson also brought in English dance mixers for an electronic beat. \"People thought I was mad when I touted the idea,\" Emmerson told Jim Carroll of *The Irish Times*. \"At the time, I was out of favour with the London club scene. I was broke and on income support but the success was extraordinary\".
## Career
Jamming in the studios at Real World, musician Peter Gabriel\'s recording facilities in Wiltshire, England, the group of musicians recorded the basis of their first album in one week. This album, *Volume 1: Sound Magic*, was released by Real World Records in 1996, and marked the debut of the Afro Celt Sound System.
\"Prior to that first album being made, none of us knew if it would work,\" musician James McNally told Larry Katz of the Boston Herald. \"We were strangers who didn\'t even speak the same language. But we were bowled over by this communication that took place beyond language.\"`{{full citation needed|date=November 2012}}`{=mediawiki} McNally, who grew up second-generation Irish in London, played whistles, keyboards, piano, bodhran, and bamboo flute.
*Sound Magic* has now sold over 300,000 copies. The band performed at festivals, raves, and dance clubs and regularly included two African musicians, Moussa Sissokho on talking drum and djembe and N\'Faly Kouyate on vocals, kora and balafon.
Just as the second album was getting off the ground, one of the group\'s core musicians, 27-year-old keyboardist Jo Bruce, (son of Cream bass player Jack Bruce), died suddenly of an asthma attack. The band was devastated, and the album was put on hold. Sinéad O\'Connor then collaborated with the band and helped them cope with their loss. \"\[O\'Connor\] blew into the studio on a windy November night and blew away again leaving us something incredibly emotional and powerful,\" McNally told Katz. \"We had this track we didn\'t know what to do with. Sinéad scribbled a few lyrics and bang! She left us completely choked up.\"`{{full citation needed|date=November 2012}}`{=mediawiki} The band used the name of O\'Connor\'s song, \"Release\", for the title of their album. *Volume 2: Release* was released in 1999, and by the spring of 2000 it had sold more than half a million copies worldwide. *Release* is also used as one of the GCSE music set works in the UK that students are required to study for their exam.
In 2000, the group was nominated for a Grammy Award in the Best World Music category. The band, composed at the time of eight members from six countries (the UK, Senegal, Guinea, Ireland, France and Kenya), took pride in its ability to bring people together through music. \"We can communicate anywhere at any corner of the planet and feel that we\'re at home,\" McNally told Patrick MacDonald of *The Seattle Times*. \"We\'re breaking down categories of world music and rock music and black music. We leave a door open to communicate with each other\'s traditions. And it\'s changed our lives\".`{{full citation needed|date=November 2012}}`{=mediawiki}
In 2001, the group released *Volume 3: Further in Time*, which climbed to number one on *Billboard*{{\'}}s Top World Music Albums chart. Featuring guest spots by Peter Gabriel and Robert Plant, the album also incorporated a heightened African sound. \"On the first two records, the pendulum swung more toward the Celtic, London club side of the equation,\" Emmerson told *The Irish Times*{{\'}} Carroll. \"For this one, we wanted to have more African vocals and input than we\'d done before.\" Again the Afro Celt Sound System met with success. Chuck Taylor of *Billboard* praised the album as \"a cultural phenomenon that bursts past the traditional boundaries of contemporary music.\"`{{full citation needed|date=November 2012}}`{=mediawiki} The single \"When You\'re Falling\", with vocals by Gabriel, became a radio hit in the United States.
In 2003, for the *Seed* album, they changed their name to Afrocelts. They reverted to the longer band name for their subsequent albums, *Pod*, a compilation of new mixes of songs from the first four albums, *Volume 5: Anatomic* (their fifth studio album), and *Capture (1995--2010)*.
They played a number of shows to promote *Volume 5: Anatomic* in 2006 and summer 2007, ending with a gig in Korea, before taking an extended break to work on side projects, amongst them *The Imagined Village* featuring Simon Emmerson and Johnny Kalsi. Starting in the summer of 2010, the band performed a series of live shows to promote *Capture (1995--2010)*, released on 6 September 2010 on Real World Records. Further performances continue to the present day, and a new album-in-progress titled *Born* was announced on their website in 2014. Following the split (see below), Emmerson\'s version of the band released the album The Source in 2016.
## Split
During 2015, the band had split into two formations, one of them including Simon Emmerson, N\'Faly Kouyate and Johnny Kalsi, the other one James McNally and Martin Russell. The split was announced on the band\'s website in January 2016. The dispute officially ended with an announcement on social media on 21 December 2016. `{{Blockquote |text=Simon Emmerson, James McNally and Martin Russell are pleased to announce that they have been able to set aside their differences and come to an amicable agreement to bring their dispute to an end. Going forward, McNally, Russell and Emmerson have agreed that Emmerson will continue to perform as Afro Celt Sound System and McNally and Russell will work under a new name to be announced in due course. While McNally, Russell and Emmerson will no longer be performing or working together they recognise, and are grateful for each other's contribution to Afro Celt Sound System over the past two decades and will be working with the extensive community of musicians that make up the long standing Afro Celt Sound System family.<ref>{{cite web|url=https://www.facebook.com/officialafroceltsoundsystem/posts/1384670074878165|title=Afro Celt Sound System|via=Facebook|archive-url=https://web.archive.org/web/20200117134949/https://www.facebook.com/officialafroceltsoundsystem/posts/1384670074878165|archive-date=17 January 2020}}</ref><ref>{{cite web |title=Statement about ACSS |url=https://www.afroceltsoundsystem.org.uk/news/statement-about-acss/ |website=Afro Celt Sound System |access-date=15 November 2020 |date=21 December 2016}}</ref>}}`{=mediawiki}
## Members
When Afro Celt Sound System formed in the mid-1990s during the Real World Recording Week, the difference between a guest artist and a band member was virtually non-existent. However, over time, a combination of people became most often associated with the name Afro Celt Sound System (while *Volume 5: Anatomic* only lists Emmerson, McNally, Ó Lionáird and Russell as regulars). The divided grouping of the band into two versions, both operating under the name Afro Celt Sound System, began in January 2016 and was resolved in December 2016 after McNally and Russell agreed to work under a different name from Emmerson.
- Simon Emmerson who died on 13 March 2023 after falling ill.
- N\'Faly Kouyate
- Johnny Kalsi
- Moussa Sissokho
- Griogair Labhruidh
- Ronan Browne
- Emer Mayock
- Davy Spillane
**Russell/McNally version**
- Martin Russell
- James McNally
- Ian Markin
- Tim Bradshaw
- Babara Bangoura
- Dorothee Munyaneza
- Kadially Kouyaté
- Dav Daheley
Other musicians who have performed or recorded with Afro Celt Sound System include: Jimmy Mahon, Demba Barry, Babara Bangoura, Iarla Ó Lionáird, Peter Gabriel, Robert Plant, Pete Lockett, Sinéad O\'Connor, Pina Kollar, Dorothee Munyaneza, Sevara Nazarkhan, Simon Massey, Jesse Cook, Martin Hayes, Eileen Ivers, Mundy, Mairéad Ní Mhaonaigh and Ciarán Tourish of Altan, Ronan Browne, Michael McGoldrick, Steáfán Hannigan, Myrdhin, Shooglenifty, Mairead Nesbitt, Nigel Eaton, Davy Spillane, Jonas Bruce, Heather Nova, Julie Murphy, Ayub Ogada, Caroline Lavelle, and Ross Ainslie.
## Discography
### Studio albums {#studio_albums}
+--------------------------------------------------------------------------------------------------------------+------+----------------------+
| Title | Year | Peak chart positions |
+==============================================================================================================+======+======================+
| UK\ | AUS\ | FRA\ |
| Peaks in the UK: | | |
| | | |
| - All except noted: full Official Chart history\|publisher=Official Charts\|access-date=5 December 2020}} | | |
| - \"When You\'re Falling\": | | |
+--------------------------------------------------------------------------------------------------------------+------+----------------------+
| *Volume 1: Sound Magic* | 1996 | 59 |
+--------------------------------------------------------------------------------------------------------------+------+----------------------+
| *Volume 2: Release* | 1999 | 38 |
+--------------------------------------------------------------------------------------------------------------+------+----------------------+
| *Volume 3: Further in Time* | 2001 | 77 |
+--------------------------------------------------------------------------------------------------------------+------+----------------------+
| *Seed* | 2003 | --- |
+--------------------------------------------------------------------------------------------------------------+------+----------------------+
| *Volume 5: Anatomic* | 2005 | --- |
+--------------------------------------------------------------------------------------------------------------+------+----------------------+
| *The Source* | 2016 | 86 |
+--------------------------------------------------------------------------------------------------------------+------+----------------------+
| *Flight* | 2018 | --- |
+--------------------------------------------------------------------------------------------------------------+------+----------------------+
| *OVA* | 2024 | --- |
+--------------------------------------------------------------------------------------------------------------+------+----------------------+
: List of studio albums, with selected chart positions
### Other albums {#other_albums}
- *Pod* (remix album) (2004)
- *Capture (1995--2010)* (2010) (compilation) No. 14 NZ
They also recorded the soundtrack for the PC game *Magic and Mayhem*, released in 1998.
### Singles
+---------------------------------------------------------+------+----------------------+-----+
| Title | Year | Peak chart positions | |
+=========================================================+======+======================+=====+
| UK\ | NLD\ | US\ | |
| | | Dance\ | |
+---------------------------------------------------------+------+----------------------+-----+
| \"Sure-As-Not\" | 1996 | --- | --- |
+---------------------------------------------------------+------+----------------------+-----+
| \"Whirl-Y-Reel\" | 1997 | 91 | --- |
+---------------------------------------------------------+------+----------------------+-----+
| \"Release\"\ | 2000 | 71 | --- |
| `{{small|(featuring [[Sinéad O'Connor]])}}`{=mediawiki} | | | |
+---------------------------------------------------------+------+----------------------+-----+
| \"When You\'re Falling\"\ | 2001 | 139 | 86 |
| `{{small|(featuring [[Peter Gabriel]])}}`{=mediawiki} | | | |
+---------------------------------------------------------+------+----------------------+-----+
: List of commercial singles, with selected chart positions
| 2025-08-01T00:00:00 |
1,167 |
Ancient philosophy
|
This page lists some links to **ancient philosophy**, namely philosophical thought extending as far as early post-classical history (c. 600 CE).
## Overview
Genuine philosophical thought, depending upon original individual insights, arose in many cultures roughly contemporaneously. Karl Jaspers termed the intense period of philosophical development beginning around the 7th century BCE and concluding around the 3rd century BCE an Axial Age in human thought.
In Western philosophy, the spread of Christianity in the Roman Empire marked the ending of Hellenistic philosophy and ushered in the beginnings of medieval philosophy, whereas in the Middle East, the spread of Islam through the Arab Empire marked the end of Old Iranian philosophy and ushered in the beginnings of early Islamic philosophy.
## Ancient Greek and Roman philosophy {#ancient_greek_and_roman_philosophy}
### Philosophers
#### Pre-Socratic philosophers {#pre_socratic_philosophers}
- Milesian School
: Thales (624 -- c 546 BCE)
: Anaximander (610 -- 546 BCE)
: Anaximenes of Miletus (c. 585 -- c. 525 BCE)
- Pythagoreans
: Pythagoras (582 -- 496 BCE)
: Philolaus (470 -- 380 BCE)
: Alcmaeon of Croton
: Archytas (428 -- 347 BCE)
- Heraclitus (535 -- 475 BCE)
- Eleatic School
: Xenophanes (570 -- 470 BCE)
: Parmenides (510 -- 440 BCE)
: Zeno of Elea (490 -- 430 BCE)
: Melissus of Samos (c. 470 BCE -- ?)
- Pluralists
: Empedocles (490 -- 430 BCE)
: Anaxagoras (500 -- 428 BCE)
- Atomists
: Leucippus (first half of 5th century BCE)
: Democritus (460 -- 370 BCE)
: Metrodorus of Chios (4th century BCE)
- Pherecydes of Syros (6th century BCE)
- Sophists
: Protagoras (490 -- 420 BCE)
: Gorgias (487 -- 376 BCE)
: Antiphon (480 -- 411 BCE)
: Prodicus (465/450 -- after 399 BCE)
: Hippias (middle of the 5th century BCE)
: Thrasymachus (459 -- 400 BCE)
: Callicles
: Critias
: Lycophron
- Diogenes of Apollonia (c. 460 BCE -- ?)
#### Classical Greek philosophers {#classical_greek_philosophers}
- Socrates (469 -- 399 BCE)
- Euclid of Megara (450 -- 380 BCE)
- Antisthenes (445 -- 360 BCE)
- Aristippus (435 -- 356 BCE)
- Plato (428 -- 347 BCE)
- Speusippus (407 -- 339 BCE)
- Diogenes of Sinope (400 -- 325 BCE)
- Xenocrates (396 -- 314 BCE)
- Aristotle (384 -- 322 BCE)
- Stilpo (380 -- 300 BCE)
- Theophrastus (370 -- 288 BCE)
#### Hellenistic philosophy {#hellenistic_philosophy}
- Pyrrho (365 -- 275 BCE)
- Epicurus (341 -- 270 BCE)
- Metrodorus of Lampsacus (the younger) (331 -- 278 BCE)
- Zeno of Citium (333 -- 263 BCE)
- Cleanthes (c. 330 -- c. 230 BCE)
- Timon (320 -- 230 BCE)
- Arcesilaus (316 -- 232 BCE)
- Menippus (3rd century BCE)
- Archimedes (c. 287 -- 212 BCE)
- Chrysippus (280 -- 207 BCE)
- Carneades (214 -- 129 BCE)
- Clitomachus (187 -- 109 BCE)
- Metrodorus of Stratonicea (late 2nd century BCE)
- Philo of Larissa (160 -- 80 BCE)
- Posidonius (135 -- 51 BCE)
- Antiochus of Ascalon (130 -- 68 BCE)
- Aenesidemus (1st century BCE)
- Agrippa (1st century CE)
### Hellenistic schools of thought {#hellenistic_schools_of_thought}
- Academic skepticism
- Cynicism
- Cyrenaicism
- Eclecticism
- Epicureanism
- Middle Platonism
- Neo-Platonism
- Neopythagoreanism
- Peripatetic School
- Pyrrhonism
- Stoicism
- Sophism
### Early Roman and Christian philosophy {#early_roman_and_christian_philosophy}
- Neoplatonism in Christianity
- School of the Sextii
### Philosophers during Roman times {#philosophers_during_roman_times}
- Cicero (106 -- 43 BCE)
- Lucretius (94 -- 55 BCE)
- Seneca (4 BCE -- 65 CE)
- Musonius Rufus (30 -- 100 CE)
- Plutarch (45 -- 120 CE)
- Epictetus (55 -- 135 CE)
- Favorinus (c. 80 -- c. 160 CE)
- Marcus Aurelius (121 -- 180 CE)
- Clement of Alexandria (150 -- 215 CE)
- Alcinous (philosopher) (2nd century CE)
- Sextus Empiricus (3rd century CE)
- Alexander of Aphrodisias (3rd century CE)
- Ammonius Saccas (3rd century CE)
- Plotinus (205 -- 270 CE)
- Porphyry (232 -- 304 CE)
- Iamblichus (242 -- 327 CE)
- Themistius (317 -- 388 CE)
- Ambrose (340 -- 397 CE)
- Hypatia of Alexandria (350 -- 415 CE)
- Augustine of Hippo (354 -- 430 CE)
- Proclus (411 -- 485 CE)
- Damascius (462 -- 540 CE)
- Boethius (472 -- 524 CE)
- Simplicius of Cilicia (490 -- 560 CE)
- John Philoponus (490 -- 570 CE)
## Ancient Iranian philosophy {#ancient_iranian_philosophy}
`{{Main article|Iranian philosophy}}`{=mediawiki} See also: *Dualism, Dualism (philosophy of mind)*
While there are ancient relations between the Indian Vedas and the Iranian Avesta, the two main families of the Indo-Iranian philosophical traditions were characterized by fundamental differences in their implications for the human being\'s position in society and their view of man\'s role in the universe. The first charter of human rights by Cyrus the Great as understood in the Cyrus cylinder is often seen as a reflection of the questions and thoughts expressed by Zarathustra and developed in Zoroastrian schools of thought of the Achaemenid Era of Iranian history.
### Schools of thought {#schools_of_thought}
Ideas and tenets of Zoroastrian schools of Early Persian philosophy are part of many works written in Middle Persian and of the extant scriptures of the Zoroastrian religion in Avestan language. Among these are treatises such as the Shikand-gumanic Vichar by Mardan-Farrux Ohrmazddadan, selections of Denkard, Wizidagīhā-ī Zātspram (\"Selections of Zātspram\") as well as older passages of the book Avesta, the Gathas which are attributed to Zarathustra himself and regarded as his \"direct teachings\".
#### Zoroastrianism
- Zarathustra
- Jamasp
- Ostanes
- Mardan-Farrux Ohrmazddadan
- Adurfarnbag Farroxzadan
- Adurbad Emedan
- *Avesta*
- *Gathas*
Anacharsis
#### Pre-Manichaean thought {#pre_manichaean_thought}
- Bardesanes
#### Manichaeism
- Mani (c. 216 -- 276 CE)
- Ammo
#### Mazdakism
- Mazdak the Elder
- Mazdak (died c. 524 or 528 CE)
#### Zurvanism
- Aesthetic Zurvanism
- Materialist Zurvanism
- Fatalistic Zurvanism
### Philosophy and the Empire {#philosophy_and_the_empire}
- Political philosophy
- Tansar
- University of Gundishapur
- Borzouye
- Bakhtshooa Gondishapuri
- Emperor Khosrau\'s philosophical discourses
- Paul the Persian
### Literature
- Pahlavi literature
## Ancient Jewish philosophy {#ancient_jewish_philosophy}
- Qohelet (c. 450-180 BCE)
- Pseudo-Aristeas (c. 2nd century BCE)
- Ben Sira (fl. 180--175 BCE)
- Aristobulus of Alexandria (181--124 BCE)
- Philo of Alexandria (30 BCE -- 45 CE)
- Wisdom of Solomon (c. 1st century BCE - 1st century CE)
- 4 Maccabees (c. 1st century CE)
- Rabbi Akiva (c. 40 -- c. 137 CE)
## Ancient Indian philosophy {#ancient_indian_philosophy}
The **ancient Indian philosophy** is a fusion of two ancient traditions: the Vedic tradition and the śramaṇa tradition.
### Vedic philosophy {#vedic_philosophy}
Indian philosophy begins with the *Vedas* wherein questions pertaining to laws of nature, the origin of the universe, and the place of man in it are asked. In the famous Rigvedic *Hymn of Creation* (Nasadiya Sukta) the poet asks:
: \"Whence all creation had its origin,
: he, whether he fashioned it or whether he did not,
: he, who surveys it all from highest heaven,
: he knows---or maybe even he does not know.\"
In the Vedic view, creation is ascribed to the self-consciousness of the primeval being (*Purusha*). This leads to the inquiry into *the one being* that underlies the diversity of empirical phenomena and the origin of all things. Cosmic order is termed *rta* and causal law by *karma*. Nature (*prakriti*) is taken to have three qualities (*sattva*, *rajas*, and *tamas*).
- Vedas
- Upanishads
- Hindu philosophy
### Sramana philosophy {#sramana_philosophy}
Jainism and Buddhism are a continuation of the Sramana school of thought. The Sramanas cultivated a pessimistic worldview of the samsara as full of suffering and advocated renunciation and austerities. They laid stress on philosophical concepts like Ahimsa, Karma, Jnana, Samsara and Moksa. Cārvāka (Sanskrit: चार्वाक) (atheist) philosophy, also known as Lokāyata, it is a system of Hindu philosophy that assumes various forms of philosophical skepticism and religious indifference. It is named after its founder, Cārvāka, author of the Bārhaspatya-sūtras.
### Classical Indian philosophy {#classical_indian_philosophy}
In classical times, these inquiries were systematized in six schools of philosophy. Some of the questions asked were:
- What is the ontological nature of consciousness?
- How is cognition itself experienced?
- Is mind (*chit*) intentional or not?
- Does cognition have its own structure?
The six schools of Indian philosophy are:
- Nyaya
- Vaisheshika
- Samkhya
- Yoga
- Mimamsa (Purva Mimamsa)
- Vedanta (Uttara Mimamsa)
### Ancient Indian philosophers {#ancient_indian_philosophers}
#### 1st millennium BCE {#st_millennium_bce}
- Parashara -- writer of *Viṣṇu Purāṇa*.
#### Philosophers of Vedic Age (c. 1500 -- c. 600 BCE) {#philosophers_of_vedic_age_c._1500_c._600_bce}
- Rishi Narayana -- seer of the Purusha Sukta of the Rig Veda.
- Seven Rishis -- Atri, Bharadwaja, Gautama, Jamadagni, Kasyapa, Vasishtha, Viswamitra.
- Other Vedic Rishis -- Gritsamada, Sandilya, Kanva etc.
- Rishaba -- Rishi mentioned in Rig Veda and later in several Puranas, and believed by Jains to be the first official religious guru of Jainism, as accredited by later followers.
- Yajnavalkya -- one of the Vedic sages, greatly influenced Buddhistic thought.
- Lopamudra
- Gargi Vachaknavi
- Maitreyi
- Parshvanatha
- Ghosha
- Angiras -- one of the seers of the Atharva Veda and author of Mundaka Upanishad.
- Uddalaka Aruni -- an Upanishadic sage who authored major portions of Chāndogya Upaniṣad.
- Ashvapati -- a King in the Later Vedic age who authored Vaishvanara Vidya of Chāndogya Upaniṣad.
- Ashtavakra -- an Upanishadic Sage mentioned in the Mahabharata, who authored Ashtavakra Gita.
#### Philosophers of Axial Age (600--185 BCE) {#philosophers_of_axial_age_600185_bce}
- Gotama (c. 600 BCE), logician, author of Nyaya Sutra
- Kanada (c. 600 BCE), founded the philosophical school of Vaisheshika, gave theory of atomism
- Mahavira (599--527 BCE) -- heavily influenced Jainism, the 24th Tirthankara of Jainism.
- Purana Kassapa
- Ajita Kesakambali
- Payasi
- *Makkhali Gośāla*
- *Sañjaya Belaṭṭhiputta*
- Mahavira
- Dandamis
- Nagasena
- Lakulisha
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- Pakudha Kaccayana
- Pāṇini (520--460 BCE), grammarian, author of Ashtadhyayi
- Kapila (c. 500 BCE), proponent of the Samkhya system of philosophy.
- Badarayana (lived between 500 BCE and 400 BCE) -- Author of Brahma Sutras.
- Jaimini (c. 400 BCE), author of Purva Mimamsa Sutras.
- Pingala (c. 500 BCE), author of the *Chandas shastra*
- Gautama Buddha (c. 480 -- c. 400 BCE), founder of Buddhist school of thought
- Śāriputra
- Chanakya (c. 350 -- c. 275 BCE), author of Arthashastra, professor (acharya) of political science at the Takshashila University
- Patañjali (c. 200 BCE), developed the philosophy of Raja Yoga in his Yoga Sutras.
- Shvetashvatara -- Author of earliest textual exposition of a systematic philosophy of Shaivism.
#### Philosophers of Golden Age (184 BCE -- 600 CE) {#philosophers_of_golden_age_184_bce_600_ce}
- Aśvaghoṣa, believed to have been the first Sanskrit dramatist, and is considered the greatest Indian poet before Kālidāsa
- Vatsyana, known for \"Kama Sutra\"
- Samantabhadra, a proponent of the Jaina doctrine of Anekantavada
- Isvarakrsna
- Aryadeva, a student of Nagarjuna and contributed significantly to the Madhyamaka
- Dharmakirti
- Haribhadra
- Pujyapada
- Buddhaghosa
- Kamandaka
- Maticandra
- Prashastapada
- Bhāviveka
- Dharmapala
- Udyotakara
- Gaudapada
- Valluvar (c. 5th century CE), wrote the Kural text, a Tamil-language treatise on morality and secular ethics
- Dignāga (c. 500), one of the founders of Buddhist school of Indian logic
- Asanga (c. 300), exponent of the Yogacara
- Bhartrihari (c. 450--510 CE), early figure in Indic linguistic theory
- Bodhidharma (c. 440--528 CE), founder of the Zen school of Buddhism
- Siddhasenadivākarasuri (5th century CE), Jain logician and author of important works in Sanskrit and Prakrit, such as Nyāyāvatāra (on logic) and Sanmatisūtra (dealing with the seven Jaina standpoints, knowledge and the objects of knowledge)
- Vasubandhu (c. 300 CE), one of the main founders of the Indian Yogacara school
- Kundakunda (2nd century CE), exponent of Jain mysticism and Jain nayas dealing with the nature of the soul and its contamination by matter, author of Pañcāstikāyasāra (Essence of the Five Existents), the Pravacanasāra (Essence of the Scripture) and the Samayasāra (Essence of the Doctrine)
- Nagarjuna (c. 150 -- 250 CE), the founder of the Madhyamaka (Middle Path) school of Mahāyāna Buddhism
- Umāsvāti or Umasvami (2nd century CE), author of first Jain work in Sanskrit, Tattvārthasūtra, expounding the Jain philosophy in a most systematized form acceptable to all sects of Jainism
- Adi Shankara -- philosopher and theologian, most renowned exponent of the Advaita Vedanta school of philosophy
## Ancient Chinese philosophy {#ancient_chinese_philosophy}
Chinese philosophy is the dominant philosophical thought in China and other countries within the East Asian cultural sphere that share a common language, including Japan, Korea, and Vietnam.
### Schools of thought {#schools_of_thought_1}
#### Hundred Schools of Thought {#hundred_schools_of_thought}
The Hundred Schools of Thought were philosophers and schools that flourished from the 6th century to 221 BCE, an era of significant cultural and intellectual expansion in China. Even though this period -- known in its earlier part as the Spring and Autumn period and the Warring States period -- in its latter part was fraught with chaos and bloody battles, it is also known as the Golden Age of Chinese philosophy because a broad range of thoughts and ideas were developed and discussed freely. The thoughts and ideas discussed and refined during this period have profoundly influenced lifestyles and social consciousness up to the present day in East Asian countries. The intellectual society of this era was characterized by itinerant scholars, who were often employed by various state rulers as advisers on the methods of government, war, and diplomacy. This period ended with the rise of the Qin dynasty and the subsequent purge of dissent. The Book of Han lists ten major schools, they are:
- Confucianism, which teaches that human beings are teachable, improvable, and perfectible through personal and communal endeavors, especially including self-cultivation and self-creation. The main idea of Confucianism is the cultivation of virtue and the development of moral perfection. Confucianism holds that one should give up one\'s life, if necessary, either passively or actively, for the sake of upholding the cardinal moral values of *ren* and *yi*.
- Legalism. Often compared with Machiavelli, and foundational for the traditional Chinese bureaucratic empire, the Legalists examined administrative methods, emphasizing a realistic consolidation of the wealth and power of autocrat and state.
- Taoism (also called Daoism), a philosophy which emphasizes the Three Jewels of the Tao: compassion, moderation, and humility, while Taoist thought generally focuses on nature, the relationship between humanity and the cosmos; health and longevity; and wu wei (action through inaction). Harmony with the Universe, or the source thereof (Tao), is the intended result of many Taoist rules and practices.
- Mohism, which advocated the idea of universal love: Mozi believed that \"everyone is equal before heaven\" and that people should seek to imitate heaven by engaging in the practice of collective love. His epistemology can be regarded as primitive materialist empiricism; he believed that human cognition ought to be based on one\'s perceptions -- one\'s sensory experiences, such as sight and hearing -- instead of imagination or internal logic, elements founded on the human capacity for abstraction. Mozi advocated frugality, condemning the Confucian emphasis on ritual and music, which he denounced as extravagant.
- Naturalism, the School of Naturalists or the Yin-yang school, which synthesized the concepts of yin and yang and the Five Elements; Zou Yan is considered the founder of this school.
- Agrarianism, or the School of Agrarianism, which advocated peasant utopian communalism and egalitarianism. The Agrarians believed that Chinese society should be modeled around that of the early sage king Shen Nong, a folk hero which was portrayed in Chinese literature as \"working in the fields, along with everyone else, and consulting with everyone else when any decision had to be reached.\"
- The Logicians or the School of Names, which focused on definition and logic. It is said to have parallels with that of the Ancient Greek sophists or dialecticians. The most notable Logician was Gongsun Longzi.
- The School of Diplomacy or School of Vertical and Horizontal \[Alliances\], which focused on practical matters instead of any moral principle, stressed political and diplomatic tactics, debate, and lobbying skills. Scholars from this school were good orators, debaters, and tacticians.
- The Miscellaneous School, which integrated teachings from different schools; for instance, Lü Buwei found scholars from different schools to write a book called Lüshi Chunqiu cooperatively. This school tried to integrate the merits of various schools and avoid their perceived flaws.
- The School of \"Minor-talks\" was not a unique school of thought but a philosophy constructed of all the thoughts discussed by and originated from ordinary people on the street.
- Another group is the School of the Military that studied strategy and the philosophy of war; Sunzi and Sun Bin were influential leaders. However, this school was not one of the \"Ten Schools\" defined by Hanshu.
#### Early Imperial China {#early_imperial_china}
The founder of the Qin dynasty, who implemented Legalism as the official philosophy, quashed Mohist and Confucianist schools. Legalism remained influential until the emperors of the Han dynasty adopted Daoism and later Confucianism as official doctrine. These latter two became the determining forces of Chinese thought until the introduction of Buddhism.
Confucianism was particularly strong during the Han dynasty, whose greatest thinker was Dong Zhongshu, who integrated Confucianism with the thoughts of the Zhongshu School and the theory of the Five Elements. He also was a promoter of the New Text school, which considered Confucius as a divine figure and a spiritual ruler of China, who foresaw and started the evolution of the world towards the Universal Peace. In contrast, there was an Old Text school that advocated the use of Confucian works written in ancient language (from this comes the denomination *Old Text*) that were so much more reliable. In particular, they refuted the assumption of Confucius as a godlike figure and considered him as the greatest sage, but simply a human and mortal.
The 3rd and 4th centuries saw the rise of the *Xuanxue* (mysterious learning), also called *Neo-Taoism*. The most influential philosophers of this movement were Wang Bi, Xiang Xiu and Guo Xiang. The main question of this school was whether Being came before Not-Being (in Chinese, *ming* and *wuming*). A peculiar feature of these Taoist thinkers, like the Seven Sages of the Bamboo Grove, was the concept of *feng liu* (lit. wind and flow), a sort of romantic spirit which encouraged following the natural and instinctive impulse.
Buddhism arrived in China around the 1st century AD, but it was not until the Northern and Southern, Sui and Tang dynasties that it gained considerable influence and acknowledgement. In the beginning, it was considered a sort of Taoist sect, and there was even a theory about Laozi, founder of Taoism, who went to India and taught his philosophy to Buddha. Mahayana Buddhism was far more successful in China than its rival Hinayana, and both Indian schools and local Chinese sects arose from the 5th century. Two chiefly important monk philosophers were Sengzhao and Daosheng. But probably the most influential and original of these schools was the Chan sect, which had an even stronger impact in Japan as the Zen sect.
### Philosophers {#philosophers_1}
- Taoism
- Laozi (5th--4th century BCE)
- Zhuangzi (4th century BCE)
- Zhang Daoling
- Zhang Jue (died 184 CE)
- Ge Hong (283 -- 343 CE)
- Confucianism
- Confucius
- Mencius
- Xun Zi (c. 312 -- 230 BCE)
- Legalism
- Li Si
- Li Kui
- Han Fei
- Mi Su Yu
- Shang Yang
- Shen Buhai
- Shen Dao
- Mohism
- Mozi
- Song Xing
- Logicians
- Deng Xi
- Hui Shi (380--305 BCE)
- Gongsun Long (c. 325 -- c. 250 BCE)
- Agrarianism
- Xu Xing
- Naturalism
- Zou Yan (305 -- 240 BCE)
- Neotaoism
- Wang Bi
- Guo Xiang
- Xiang Xiu
- School of Diplomacy
- Guiguzi
- Su Qin (380 -- 284 BCE)
- Zhang Yi (bef. 329 -- 309 BCE)
- Yue Yi
- Li Yiji (268 -- 204 BCE)
- Military strategy
- Sunzi (c. 500 BCE)
- Sun Bin (died 316 BCE)
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Antisymmetric relation
|
In mathematics, a binary relation $R$ on a set $X$ is **antisymmetric** if there is no pair of *distinct* elements of $X$ each of which is related by $R$ to the other. More formally, $R$ is antisymmetric precisely if for all $a, b \in X,$ $\text{if } \,aRb\, \text{ with } \,a \neq b\, \text{ then } \,bRa\, \text{ must not hold},$ or equivalently, $\text{if } \,aRb\, \text{ and } \,bRa\, \text{ then } \,a = b.$ The definition of antisymmetry says nothing about whether $aRa$ actually holds or not for any $a$. An antisymmetric relation $R$ on a set $X$ may be reflexive (that is, $aRa$ for all $a \in X$), irreflexive (that is, $aRa$ for no $a \in X$), or neither reflexive nor irreflexive. A relation is asymmetric if and only if it is both antisymmetric and irreflexive.
## Examples
The divisibility relation on the natural numbers is an important example of an antisymmetric relation. In this context, antisymmetry means that the only way each of two numbers can be divisible by the other is if the two are, in fact, the same number; equivalently, if $n$ and $m$ are distinct and $n$ is a factor of $m,$ then $m$ cannot be a factor of $n.$ For example, 12 is divisible by 4, but 4 is not divisible by 12.
The usual order relation $\,\leq\,$ on the real numbers is antisymmetric: if for two real numbers $x$ and $y$ both inequalities $x \leq y$ and $y \leq x$ hold, then $x$ and $y$ must be equal. Similarly, the subset order $\,\subseteq\,$ on the subsets of any given set is antisymmetric: given two sets $A$ and $B,$ if every element in $A$ also is in $B$ and every element in $B$ is also in $A,$ then $A$ and $B$ must contain all the same elements and therefore be equal: $A \subseteq B \text{ and } B \subseteq A \text{ implies } A = B$ A real-life example of a relation that is typically antisymmetric is \"paid the restaurant bill of\" (understood as restricted to a given occasion). Typically, some people pay their own bills, while others pay for their spouses or friends. As long as no two people pay each other\'s bills, the relation is antisymmetric.
## Properties
Partial and total orders are antisymmetric by definition. A relation can be both symmetric and antisymmetric (in this case, it must be coreflexive), and there are relations which are neither symmetric nor antisymmetric (for example, the \"preys on\" relation on biological species).
Antisymmetry is different from asymmetry: a relation is asymmetric if and only if it is antisymmetric and irreflexive.
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Astrometry
|
**Astrometry** is a branch of astronomy that involves precise measurements of the positions and movements of stars and other celestial bodies. It provides the kinematics and physical origin of the Solar System and this galaxy, the Milky Way.
## History
The history of astrometry is linked to the history of star catalogues, which gave astronomers reference points for objects in the sky so they could track their movements. This can be dated back to the ancient Greek astronomer Hipparchus, who around 190 BC used the catalogue of his predecessors Timocharis and Aristillus to discover Earth\'s precession. In doing so, he also developed the brightness scale still in use today. Hipparchus compiled a catalogue with at least 850 stars and their positions. Hipparchus\'s successor, Ptolemy, included a catalogue of 1,022 stars in his work the *Almagest*, giving their location, coordinates, and brightness.
In the 10th century, the Iranian astronomer Abd al-Rahman al-Sufi carried out observations on the stars and described their positions, magnitudes and star color; furthermore, he provided drawings for each constellation, which are depicted in his *Book of Fixed Stars*. Egyptian mathematician Ibn Yunus observed more than 10,000 entries for the Sun\'s position for many years using a large astrolabe with a diameter of nearly 1.4 metres. His observations on eclipses were still used centuries later in Canadian--American astronomer Simon Newcomb\'s investigations on the motion of the Moon, while his other observations of the motions of the planets Jupiter and Saturn inspired French scholar Laplace\'s *Obliquity of the Ecliptic* and *Inequalities of Jupiter and Saturn*. In the 15th century, the Timurid astronomer Ulugh Beg compiled the *Zij-i-Sultani*, in which he catalogued 1,019 stars. Like the earlier catalogs of Hipparchus and Ptolemy, Ulugh Beg\'s catalogue is estimated to have been precise to within approximately 20 minutes of arc.
In the 16th century, Danish astronomer Tycho Brahe used improved instruments, including large mural instruments, to measure star positions more accurately than previously, with a precision of 15--35 arcsec. Ottoman scholar Taqi al-Din measured the right ascension of the stars at the Constantinople Observatory of Taqi ad-Din using the \"observational clock\" he invented. When telescopes became commonplace, setting circles sped measurements
English astronomer James Bradley first tried to measure stellar parallaxes in 1729. The stellar movement proved too insignificant for his telescope, but he instead discovered the aberration of light and the nutation of the Earth\'s axis. His cataloguing of 3222 stars was refined in 1807 by German astronomer Friedrich Bessel, the father of modern astrometry. He made the first measurement of stellar parallax: 0.3 arcsec for the binary star 61 Cygni. In 1872, British astronomer William Huggins used spectroscopy to measure the radial velocity of several prominent stars, including Sirius.
Being very difficult to measure, only about 60 stellar parallaxes had been obtained by the end of the 19th century, mostly by use of the filar micrometer. Astrographs using astronomical photographic plates sped the process in the early 20th century. Automated plate-measuring machines and more sophisticated computer technology of the 1960s allowed more efficient compilation of star catalogues. Started in the late 19th century, the project Carte du Ciel to improve star mapping could not be finished but made photography a common technique for astrometry. In the 1980s, charge-coupled devices (CCDs) replaced photographic plates and reduced optical uncertainties to one milliarcsecond. This technology made astrometry less expensive, opening the field to an amateur audience.
In 1989, the European Space Agency\'s Hipparcos satellite took astrometry into orbit, where it could be less affected by mechanical forces of the Earth and optical distortions from its atmosphere. Operated from 1989 to 1993, Hipparcos measured large and small angles on the sky with much greater precision than any previous optical telescopes. During its 4-year run, the positions, parallaxes, and proper motions of 118,218 stars were determined with an unprecedented degree of accuracy. A new \"Tycho catalog\" drew together a database of 1,058,332 stars to within 20-30 mas (milliarcseconds). Additional catalogues were compiled for the 23,882 double and multiple stars and 11,597 variable stars also analyzed during the Hipparcos mission. In 2013, the Gaia satellite was launched and improved the accuracy of Hipparcos. The precision was improved by a factor of 100 and enabled the mapping of a billion stars. Today, the catalogue most often used is USNO-B1.0, an all-sky catalogue that tracks proper motions, positions, magnitudes and other characteristics for over one billion stellar objects. During the past 50 years, 7,435 Schmidt camera plates were used to complete several sky surveys that make the data in USNO-B1.0 accurate to within 0.2 arcsec.
## Applications
Apart from the fundamental function of providing astronomers with a reference frame to report their observations in, astrometry is also fundamental for fields like celestial mechanics, stellar dynamics and galactic astronomy. In observational astronomy, astrometric techniques help identify stellar objects by their unique motions. It is instrumental for keeping time, in that UTC is essentially the atomic time synchronized to Earth\'s rotation by means of exact astronomical observations. Astrometry is an important step in the cosmic distance ladder because it establishes parallax distance estimates for stars in the Milky Way.
Astrometry has also been used to support claims of extrasolar planet detection by measuring the displacement the proposed planets cause in their parent star\'s apparent position on the sky, due to their mutual orbit around the center of mass of the system. Astrometry is more accurate in space missions that are not affected by the distorting effects of the Earth\'s atmosphere. NASA\'s planned Space Interferometry Mission (SIM PlanetQuest) (now cancelled) was to utilize astrometric techniques to detect terrestrial planets orbiting 200 or so of the nearest solar-type stars. The European Space Agency\'s Gaia Mission, launched in 2013, applies astrometric techniques in its stellar census. In addition to the detection of exoplanets, it can also be used to determine their mass.
Astrometric measurements are used by astrophysicists to constrain certain models in celestial mechanics. By measuring the velocities of pulsars, it is possible to put a limit on the asymmetry of supernova explosions. Also, astrometric results are used to determine the distribution of dark matter in the galaxy.
Astronomers use astrometric techniques for the tracking of near-Earth objects. Astrometry is responsible for the detection of many record-breaking Solar System objects. To find such objects astrometrically, astronomers use telescopes to survey the sky and large-area cameras to take pictures at various determined intervals. By studying these images, they can detect Solar System objects by their movements relative to the background stars, which remain fixed. Once a movement per unit time is observed, astronomers compensate for the parallax caused by Earth\'s motion during this time and the heliocentric distance to this object is calculated. Using this distance and other photographs, more information about the object, including its orbital elements, can be obtained. Asteroid impact avoidance is among the purposes.
Quaoar and Sedna are two trans-Neptunian dwarf planets discovered in this way by Michael E. Brown and others at Caltech using the Palomar Observatory\'s Samuel Oschin telescope of 48 in and the Palomar-Quest large-area CCD camera. The ability of astronomers to track the positions and movements of such celestial bodies is crucial to the understanding of the Solar System and its interrelated past, present, and future with others in the Universe.
## Statistics
A fundamental aspect of astrometry is error correction. Various factors introduce errors into the measurement of stellar positions, including atmospheric conditions, imperfections in the instruments and errors by the observer or the measuring instruments. Many of these errors can be reduced by various techniques, such as through instrument improvements and compensations to the data. The results are then analyzed using statistical methods to compute data estimates and error ranges.
## Computer programs {#computer_programs}
- [XParallax viu (Free application for Windows)](https://sourceforge.net/projects/xparallaxviu/)
- [Astrometrica (Application for Windows)](http://www.astrometrica.at/)
- [Astrometry.net (Online blind astrometry)](https://web.archive.org/web/20101015122353/http://www.astrometry.net/)
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Amber Diceless Roleplaying Game
|
The ***Amber Diceless Roleplaying Game*** is a role-playing game created and written by Erick Wujcik, set in the fictional universe created by author Roger Zelazny for his *Chronicles of Amber*. The game is unusual in that no dice are used in resolving conflicts or player actions; instead a simple diceless system of comparative ability, and narrative description of the action by the players and gamemaster, is used to determine how situations are resolved.
*Amber DRPG* was created in the 1980s, and is much more focused on relationships and roleplaying than most of the roleplaying games of that era. Most *Amber* characters are members of the two ruling classes in the *Amber* multiverse, and are much more advanced in matters of strength, endurance, psyche, warfare and sorcery than ordinary beings. This often means that the only individuals who are capable of opposing a character are from his or her family, a fact that leads to much suspicion and intrigue.
## History
Erick Wujcik wanted to design a role-playing game based on *Amber* for West End Games, and they agreed to look at his work. Wujcik intended to integrate the feel of the *Amber* setting from the novels into a role-playing game, and playtested his system for a few months at the Michigan Gaming Center where he decided to try it out as a diceless game. West End Games was not interested in a diceless role-playing game, so Wujcik acquired the role-playing game rights to *Amber* and offered the game to R. Talsorian Games, until he withdrew over creative differences. Wujcik then founded Phage Press, and published *Amber Diceless Role-playing* in 1991.
The original 256-page game book was published in 1991 by Phage Press, covering material from the first five novels (the \"Corwin Cycle\") and some details -- sorcery and the Logrus -- from the remaining five novels (the \"Merlin Cycle\"), in order to allow players to roleplay characters from the Courts of Chaos. Some details were changed slightly to allow more player choice -- for example, players can be full Trump Artists without having walked the Pattern or the Logrus, which Merlin says is impossible; and players\' psychic abilities are far greater than those shown in the books.
A 256-page companion volume, *Shadow Knight*, was published in 1993. This supplemental rule book includes the remaining elements from the Merlin novels, such as Broken Patterns, and allows players to create Constructs such as Merlin\'s Ghostwheel. The book presents the second series of novels not as additions to the series\' continuity but as an example of a roleplaying campaign with Merlin, Luke, Julia, Jurt and Coral as the PCs. The remainder of the book is a collection of essays on the game, statistics for the new characters and an update of the older ones in light of their appearance in the second series, and (perhaps most usefully for GMs) plot summaries of each of the ten books. The book includes some material from the short story \"The Salesman\'s Tale,\" and some unpublished material cut from *Prince of Chaos*, notably Coral\'s pregnancy by Merlin.
Both books were translated into French and published by Jeux Descartes in 1994 and 1995.
A third book, *Rebma*, was promised. Cover art was commissioned and pre-orders were taken, but it was never published. Wujcik also expressed a desire to create a book giving greater detail to the Courts of Chaos. The publishing rights to the *Amber DRPG* games were acquired in 2004 by Guardians of Order, who took over sales of the game and announced their intention to release a new edition of the game. However, no new edition was released before Guardians of Order went out of business in 2006. The two existing books are now out-of-print, but they have been made available as PDF downloads.
In June 2007 a new publishing company, headed by Edwin Voskamp and Eleanor Todd, was formed with the express purpose of bringing *Amber DRPG* back into print. The new company is named *Diceless by Design*.
In May 2010, *Rite Publishing* secured a license from Diceless by Design to use the rules system with a new setting in the creation of a new product to be written by industry and system veteran Jason Durall. The project **Lords of Gossamer & Shadow (Diceless)** was funded via Kickstarter in May 2013. In Sept 2013 the project was completed, and on in Nov 2013 Lords of Gossamer and Shadow (Diceless) was released publicly in full-color Print and PDF, along with additional supplements and continued support.
## Setting
The game is set in the multiverse described in Zelazny\'s *Chronicles of Amber*. The first book assumes that gamemasters will set their campaigns after the Patternfall war; that is, after the end of the fifth book in the series, *The Courts of Chaos*, but uses material from the following books to describe those parts of Zelazny\'s cosmology that were featured there in more detail. The *Amber* multiverse consists of **Amber**, a city at one pole of the universe wherein is found the Pattern, the symbol of Order; The **Courts of Chaos**, an assembly of worlds at the other pole where can be found the Logrus, the manifestation of Chaos, and the Abyss, the source or end of all reality; and **Shadow**, the collection of all possible universes (shadows) between and around them. Inhabitants of either pole can use one or both of the Pattern and the Logrus to travel through Shadow.
It is assumed that players will portray the children of the main characters from the books -- the ruling family of Amber, known as the Elder Amberites -- or a resident of the Courts. However, since some feel that being the children of the main characters is too limiting, it is fairly common to either start with King Oberon\'s death *before* the book begins and roleplay the Elder Amberites as they vie for the throne; or to populate Amber from scratch with a different set of Elder Amberites. The former option is one presented in the book; the latter is known in the Amber community as an \"Amethyst\" game. A third option is to have the players portray Corwin\'s children, in an Amber-like city built around Corwin\'s pattern; this is sometimes called an \"Argent\" game, since one of Corwin\'s heraldic colours is Silver.
## System
### Attributes
Characters in *Amber DRPG* are represented by four attributes: *Psyche*, *Strength*, *Endurance* and *Warfare*.
- **Psyche** is used for feats of willpower or magic
- **Strength** is used for feats of strength or unarmed combat
- **Endurance** is used for feats of endurance
- **Warfare** is used for armed combat, from duelling to commanding armies
The attributes run from −25 (normal human level), through −10 (normal level for a denizen of the Courts of Chaos) and 0 (normal level for an inhabitant of Amber), upwards without limit. Scores above 0 are \"ranked\", with the highest score being ranked 1st, the next-highest 2nd, and so on. The character with 1st rank in each attribute is considered \"superior\" in that attribute, being considered to be substantially better than the character with 2nd rank even if the difference in scores is small. All else being equal, a character with a higher rank in an attribute will always win a contest based on that attribute.
#### The Attribute Auction {#the_attribute_auction}
A character\'s ability scores are purchased during character creation in an auction; players get 100 character points, and bid on each attribute in turn. The character who bids the most for an attribute is \"ranked\" first and is considered superior to all other characters in that attribute. Unlike conventional auctions, bids are non-refundable; if one player bids 65 for psyche and another wins with a bid of 66, then the character with 66 is \"superior\" to the character with 65 even though there is only one bid difference. Instead, lower bidding characters are ranked in ascending order according to how much they have bid, the characters becoming progressively weaker in that attribute as they pay less for it. After the auction, players can secretly pay extra points to raise their ranks, but they can only pay to raise their scores to an existing rank. Further, a character with a bid-for rank is considered to have a slight advantage over character with a bought-up rank.
The Auction simulates a \'history\' of competition between the descendants of Oberon for player characters who have not had dozens of decades to get to know each other. Through the competitive Auction, characters may begin the game vying for standings. The auction serves to introduce some unpredictability into character creation without the need to resort to dice, cards, or other randomizing devices. A player may intend, for example, to create a character who is a strong, mighty warrior, but being \"outplayed\" in the auction may result in lower attribute scores than anticipated, therefore necessitating a change of character concept. Since a player cannot control another player\'s bids, and since all bids are non-refundable, the auction involves a considerable amount of strategizing and prioritization by players. A willingness to spend as many points as possible on an attribute may improve your chances of a high ranking, but too reckless a spending strategy could leave a player with few points to spend on powers and objects. In a hotly contested auction, such as for the important attribute of warfare, the most valuable skill is the ability to force one\'s opponents to back down. With two or more equally determined players, this can result in a \"bidding war,\" in which the attribute is driven up by increments to large sums. An alternative strategy is to try to cow other players into submission with a high opening bid. Most players bid low amounts between one and ten points in an initial bid in order to feel out the competition and to save points for other uses. A high enough opening bid could signal a player\'s determination to be first ranked in that attribute, thereby dissuading others from competing.
#### Psyche in *Amber DRPG* compared to the *Chronicles* {#psyche_in_amber_drpg_compared_to_the_chronicles}
Characters with high psyche are presented as having strong telepathic abilities, being able to hypnotise and even mentally dominate any character with lesser psyche with whom they can make eye-contact. This is likely due to three scenes in the *Chronicles*: first, when Eric paralyzes Corwin with an attack across the Trump and refuses to desist because one or the other would be dominated; second, when Corwin faces the demon Strygalldwir, it is able to wrestle mentally with him when their gazes meet; and third, when Fiona is able to keep Brand immobile in the final battle at the Courts of Chaos. However, in general, the books only feature mental battles when there is some reason for mind-to-mind contact (for example, Trump contact) and magic or Trump is involved in all three of the above conflicts, so it is not clear whether Zelazny intended his characters to have such a power; the combination of Brand\'s \"living trump\" powers and his high Psyche (as presented in the roleplaying game) would have guaranteed him victory over Corwin. *Shadow Knight* does address this inconsistency somewhat, by presenting the \"living trump\" abilities as somewhat limited.
### Powers
Characters in *Amber DRPG* have access to the powers seen in the *Chronicles of Amber*: *Pattern*, *Logrus*, *Shape-shifting*, *Trump*, and *magic*.
- **Pattern:** A character who has walked the pattern can walk in shadow to any possible universe, and while there can manipulate probability.
- **Logrus:** A character who has mastered the Logrus can send out Logrus tendrils and pull themselves or objects through shadow.
- **Shape-shifting:** Shape-shifters can alter their physical form and abilities.
- **Trump:** Trump Artists can create Trumps, a sort of tarot card which allows mental communication and travel. The book features Trump portraits of each of the elder Amberites. The trump picture of Corwin is executed in a subtly different style -- and has features very similar to Roger Zelazny\'s.
- **Magic:** Three types of magic are detailed: **Power Words**, with a quick, small effect; **Sorcery**, with pre-prepared spells as in many other game systems; and **Conjuration**, the creation of small objects.
Each of the first four powers is available in an advanced form.
### Artifacts, Personal shadows and Constructs {#artifacts_personal_shadows_and_constructs}
While a character with Pattern, Logrus or Conjuration can acquire virtually any object, players can choose to spend character points to obtain objects with particular virtues -- unbreakability, or a mind of their own. Since they have paid points for the items, they are a part of the character\'s legend, and cannot lightly be destroyed. Similarly, a character can find any possible universe, but they can spend character points to know of or inhabit shadows which are (in some sense) \"real\" and therefore useful. The expansion, *Shadow Knight*, adds Constructs -- artifacts with connections to shadows.
### Stuff
Unspent character points become **good stuff** -- a good luck for the character. Players are also allowed to overspend (in moderation), with the points becoming **bad stuff** -- bad luck which the Gamemaster should inflict on the character. Stuff governs how non-player characters perceive and respond to the character: characters with good stuff will often receive friendly or helpful reactions, while characters with bad stuff are often treated with suspicion or hostility.
As well as representing luck, stuff can be seen as representing a character\'s outlook on the universe: characters with good stuff seeing the multiverse as a cheerful place, while characters with bad stuff see it as hostile.
### Conflict resolution {#conflict_resolution}
In any given fair conflict between two characters, the character with the higher score in the relevant attribute will eventually win. The key words here are *fair* and *eventually* -- if characters\' ranks are close, and the weaker character has obtained some advantage, then the weaker character can escape defeat or perhaps prevail. Close ranks result in longer contests while greater difference between ranks result in fast resolution. Alternatively, if characters\' attribute ranks are close, the weaker character can try to change the relevant attribute by changing the nature of the conflict. For example, if two characters are wrestling the relevant attribute is Strength; a character could reveal a weapon, changing it to Warfare; they could try to overcome the other character\'s mind using a power, changing it to Psyche; or they could concentrate their strength on defense, changing it to Endurance. If there is a substantial difference between characters\' ranks, the conflict is generally over before the weaker character can react.
### The \"Golden Rule\" {#the_golden_rule}
*Amber DRPG* advises gamemasters to change rules as they see fit, even to the point of adding or removing powers or attributes.
## Reception
Steve Crow reviewed *Amber Diceless Roleplaying Game* in *White Wolf* #31 (May/June, 1992), rating it a 4 out of 5 and stated that \"It is undoubtedly a game for experienced gamers. While I would not recommend *Amber* to novices, it is a must buy for experienced gamemasters and players looking for new challenges.\"
In the June 1992 edition of *Dragon* (Issue 182), both Lester Smith and Allen Varney published reviews of this game.
- Smith admired the professional production qualities of the 256-page rulebook, noting that because it was Smyth sewn in 32-page signatures, the book would always lie flat when opened. However, he found the typeface difficult to read, and the lack a coherent hierarchy of rules increased the reading difficulty as well. Smith admired the Attribute Auction and point-buy system for skills, and the focus on roleplaying in place of dice-rolling, but he mused that all of the roleplaying would mean \"GMs have to spend quite a bit of time and creative effort coming up with wide-reaching plots for their players to work through. Canned, linear adventures just won\'t serve.\" He concluded by stating that the diceless system is not for every gamer: \"As impressed as I am with the game, do I think it is the \'end-all\' of role-playing games, or that diceless systems are the wave of the future? I\'ll give a firm "No" on both counts\... However, I certainly do think that the *Amber Diceless Roleplaying Game* is destined for great popularity and a niche among the most respected of role-playing game designs.\"
- Allen Varney thought the \"Attribute Auction\" to be \"brilliant and elegant\", but he wondered if character advancement was perhaps too slow to keep marginal players interested. He also believed that being a gamemaster would be \"tough work. Proceed with caution.\" Varney recommended that players need some familiarity with the first five \"Amber\" novels by Zelazny. He concluded, \"The intensity of the *Amber* game indicates \[game designer Erik \] Wujcik is on to something. When success in every action depends on the role and not the roll, players develop a sense of both control and urgency, along with creativity that borders on mania.\"
In Issue 65 of *Challenge*, Dirk DeJong had a good first impression of the game, especially the information provided about the Amber family members and their various flaws and strengths. However he found that \"The biggest problem with this endeavor, and its downfall, is the nature of the conflict systems. First, they are diceless, really diceless, and don\'t involve any sort of random factors at all, aside from those that you can introduce by roleplaying them out. Thus, if you get involved with a character who\'s better than you at sword-fighting, even if only by one point out of 100, you\'re pretty much dead meat, unless you can act your way out.\" DeJong also disagreed with the suggestion that if the referee and players disagreed with a rule to simply remove it from the game. \"I thought the entire idea of using rules and random results was to prevent the type of arguments that I can see arising from this setup.\" DeJong concluded on an ambivalent note, saying, \"If you love Zelazny and the Amber series, jump on it, as this is the premier sourcebook for running an Amber campaign. \[\...\] Personally, I just can\'t get turned on by a system that expects me to either be content with a simple subtraction of numbers to find out who won, or to describe an entire combat blow by blow, just so that I can attempt some trick to win.\"
Loyd Blankenship reviewed *Amber* in *Pyramid* #2 (July/Aug., 1993), and stated that \"*Amber* is a valuable resource to a GM - even if he isn\'t running an *Amber* game. For gamers who have an aspiring actor or actress lurking within their breast, or for someone running a campaign via electronic mail or message base, *Amber* should be given serious consideration.\"
In his 2023 book *Monsters, Aliens, and Holes in the Ground*, RPG historian Stu Horvath noted, \"There hasn\'t been an RPG quite like *Amber*, before or since. Bold though it was, the game didn\'t do very well commercially. The lack of dice became a flashpoint of controversy, with dice enthusiasts dramatically swearing off the game. That\'s a bit ridiculous, but it does get at a key hurdle *Amber* face: People *like* rolling dice. They\'ve been doing it for thousands of years and a significant part of the appeal of RPGs is giving dice, often in sparkly colours, a toss.\"
## Community
Despite the game\'s out-of-print status, a thriving convention scene exists supporting the game. Amber conventions, known as *Ambercons*, are held yearly in Massachusetts, Michigan, Portland (United States), Milton Keynes (England), Belfast (Northern Ireland) and Modena, Italy. Additionally, Phage Press published 12 volumes of a dedicated *Amber DRPG* magazine called *Amberzine*. Some *Amberzine* issues are still available from Phage Press.
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Applet
|
In computing, an **applet** is any small application that performs one specific task that runs within the scope of a dedicated widget engine or a larger program, often as a plug-in. The term is frequently used to refer to a Java applet, a program written in the Java programming language that is designed to be placed on a web page. Applets are typical examples of transient and auxiliary applications that do not monopolize the user\'s attention. Applets are not full-featured application programs, and are intended to be easily accessible.
## History
The word *applet* was first used in 1990 in *PC Magazine*. However, the concept of an applet, or more broadly a small interpreted program downloaded and executed by the user, dates at least to RFC 5 (1969) by Jeff Rulifson, which described the Decode-Encode Language, which was designed to allow remote use of the oN-Line System over ARPANET, by downloading small programs to enhance the interaction. This has been specifically credited as a forerunner of Java\'s downloadable programs in RFC 2555.
## Applet as an extension of other software {#applet_as_an_extension_of_other_software}
In some cases, an applet does not run independently. These applets must run either in a container provided by a host program, through a plugin, or a variety of other applications including mobile devices that support the applet programming model.
### Web-based applets {#web_based_applets}
Applets were used to provide interactive features to web applications that historically could not be provided by HTML alone. They could capture mouse input and also had controls like buttons or check boxes. In response to the user action, an applet could change the provided graphic content. This made applets well suited for demonstration, visualization, and teaching. There were online applet collections for studying various subjects, from physics to heart physiology. Applets were also used to create online game collections that allowed players to compete against live opponents in real-time.
An applet could also be a text area only, providing, for instance, a cross-platform command-line interface to some remote system. If needed, an applet could leave the dedicated area and run as a separate window. However, applets had very little control over web page content outside the applet dedicated area, so they were less useful for improving the site appearance in general (while applets like news tickers or WYSIWYG editors are also known). Applets could also play media in formats that are not natively supported by the browser.
HTML pages could embed parameters that were passed to the applet. Hence, the same applet could appear differently depending on the parameters that were passed.
Examples of Web-based applets include:
- QuickTime movies
- Flash movies
- Windows Media Player applets, used to display embedded video files in Internet Explorer (and other browsers that supported the plugin)
- 3D modeling display applets, used to rotate and zoom a model
- Browser games that were applet-based, though some developed into fully functional applications that required installation.
### Applet Vs. Subroutine {#applet_vs._subroutine}
A larger application distinguishes its applets through several features:
- Applets execute only on the \"client\" platform environment of a system, as contrasted from \"Servlet\". As such, an applet provides functionality or performance beyond the default capabilities of its container (the browser).
- The container restricts applets\' capabilities.
- Applets are written in a language different from the scripting or HTML language that invokes it. The applet is written in a compiled language, whereas the scripting language of the container is an interpreted language, hence the greater performance or functionality of the applet. Unlike a subroutine, a complete web component can be implemented as an applet.
## Java applets {#java_applets}
A Java applet is a Java program that is launched from HTML and run in a web browser. It takes code from server and run in a web browser. It can provide web applications with interactive features that cannot be provided by HTML. Since Java\'s bytecode is platform-independent, Java applets can be executed by browsers running under many platforms, including Windows, Unix, macOS, and Linux. When a Java technology-enabled web browser processes a page that contains an applet, the applet\'s code is transferred to the client\'s system and executed by the browser\'s Java virtual machine. An HTML page references an applet either via the deprecated `{{tag|applet|o}}`{=mediawiki} tag or via its replacement, the `{{tag|object|o}}`{=mediawiki} tag.
## Security
Recent developments in the coding of applications, including mobile and embedded systems, have led to the awareness of the security of applets.
### Open platform applets {#open_platform_applets}
Applets in an open platform environment should provide secure interactions between different applications. A compositional approach can be used to provide security for open platform applets. Advanced compositional verification methods have been developed for secure applet interactions.
### Java applets {#java_applets_1}
A Java applet contains different security models: unsigned Java applet security, signed Java applet security, and self-signed Java applet security.
### Web-based applets {#web_based_applets_1}
In an applet-enabled web browser, many methods can be used to provide applet security for malicious applets. A malicious applet can infect a computer system in many ways, including denial of service, invasion of privacy, and annoyance. A typical solution for malicious applets is to make the web browser to monitor applets\' activities. This will result in a web browser that will enable the manual or automatic stopping of malicious applets.
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Area
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**Area** is the measure of a region\'s size on a surface. The area of a plane region or *plane area* refers to the area of a shape or planar lamina, while *surface area* refers to the area of an open surface or the boundary of a three-dimensional object. Area can be understood as the amount of material with a given thickness that would be necessary to fashion a model of the shape, or the amount of paint necessary to cover the surface with a single coat. It is the two-dimensional analogue of the length of a curve (a one-dimensional concept) or the volume of a solid (a three-dimensional concept). Two different regions may have the same area (as in squaring the circle); by synecdoche, \"area\" sometimes is used to refer to the region, as in a \"polygonal area\".
The area of a shape can be measured by comparing the shape to squares of a fixed size. In the International System of Units (SI), the standard unit of area is the square metre (written as m^2^), which is the area of a square whose sides are one metre long. A shape with an area of three square metres would have the same area as three such squares. In mathematics, the unit square is defined to have area one, and the area of any other shape or surface is a dimensionless real number.
There are several well-known formulas for the areas of simple shapes such as triangles, rectangles, and circles. Using these formulas, the area of any polygon can be found by dividing the polygon into triangles. For shapes with curved boundary, calculus is usually required to compute the area. Indeed, the problem of determining the area of plane figures was a major motivation for the historical development of calculus.
For a solid shape such as a sphere, cone, or cylinder, the area of its boundary surface is called the surface area. Formulas for the surface areas of simple shapes were computed by the ancient Greeks, but computing the surface area of a more complicated shape usually requires multivariable calculus.
Area plays an important role in modern mathematics. In addition to its obvious importance in geometry and calculus, area is related to the definition of determinants in linear algebra, and is a basic property of surfaces in differential geometry. In analysis, the area of a subset of the plane is defined using Lebesgue measure, though not every subset is measurable if one supposes the axiom of choice. In general, area in higher mathematics is seen as a special case of volume for two-dimensional regions.
Area can be defined through the use of axioms, defining it as a function of a collection of certain plane figures to the set of real numbers. It can be proved that such a function exists.
## Formal definition {#formal_definition}
An approach to defining what is meant by \"area\" is through axioms. \"Area\" can be defined as a function from a collection M of a special kinds of plane figures (termed measurable sets) to the set of real numbers, which satisfies the following properties:
- For all *S* in *M*, `{{nowrap|''a''(''S'') ≥ 0}}`{=mediawiki}.
- If *S* and *T* are in *M* then so are `{{nowrap|''S'' ∪ ''T''}}`{=mediawiki} and `{{nowrap|''S'' ∩ ''T''}}`{=mediawiki}, and also `{{nowrap|1=''a''(''S''∪''T'') = ''a''(''S'') + ''a''(''T'') − ''a''(''S'' ∩ ''T'')}}`{=mediawiki}.
- If *S* and *T* are in *M* with `{{nowrap|''S'' ⊆ ''T''}}`{=mediawiki} then `{{nowrap|''T'' − ''S''}}`{=mediawiki} is in *M* and `{{nowrap|1=''a''(''T''−''S'') = ''a''(''T'') − ''a''(''S'')}}`{=mediawiki}.
- If a set *S* is in *M* and *S* is congruent to *T* then *T* is also in *M* and `{{nowrap|1=''a''(''S'') = ''a''(''T'')}}`{=mediawiki}.
- Every rectangle *R* is in *M*. If the rectangle has length *h* and breadth *k* then `{{nowrap|1=''a''(''R'') = ''hk''}}`{=mediawiki}.
- Let *Q* be a set enclosed between two step regions *S* and *T*. A step region is formed from a finite union of adjacent rectangles resting on a common base, i.e. `{{nowrap|''S'' ⊆ ''Q'' ⊆ ''T''}}`{=mediawiki}. If there is a unique number *c* such that `{{nowrap|''a''(''S'') ≤ c ≤ ''a''(''T'')}}`{=mediawiki} for all such step regions *S* and *T*, then `{{nowrap|1=''a''(''Q'') = ''c''}}`{=mediawiki}.
It can be proved that such an area function actually exists.
## Units
Every unit of length has a corresponding unit of area, namely the area of a square with the given side length. Thus areas can be measured in square metres (m^2^), square centimetres (cm^2^), square millimetres (mm^2^), square kilometres (km^2^), square feet (ft^2^), square yards (yd^2^), square miles (mi^2^), and so forth. Algebraically, these units can be thought of as the squares of the corresponding length units.
The SI unit of area is the square metre, which is considered an SI derived unit.
### Conversions
Calculation of the area of a square whose length and width are 1 metre would be:
1 metre × 1 metre = 1 m^2^
and so, a rectangle with different sides (say length of 3 metres and width of 2 metres) would have an area in square units that can be calculated as:
3 metres × 2 metres = 6 m^2^. This is equivalent to 6 million square millimetres. Other useful conversions are:
- 1 square kilometre = 1,000,000 square metres
- 1 square metre = 10,000 square centimetres = 1,000,000 square millimetres
- 1 square centimetre = 100 square millimetres.
#### Non-metric units {#non_metric_units}
In non-metric units, the conversion between two square units is the square of the conversion between the corresponding length units.
: 1 foot = 12 inches,
the relationship between square feet and square inches is
: 1 square foot = 144 square inches,
where 144 = 12^2^ = 12 × 12. Similarly:
- 1 square yard = 9 square feet
- 1 square mile = 3,097,600 square yards = 27,878,400 square feet
In addition, conversion factors include:
- 1 square inch = 6.4516 square centimetres
- 1 square foot = `{{gaps|0.092|903|04}}`{=mediawiki} square metres
- 1 square yard = `{{gaps|0.836|127|36}}`{=mediawiki} square metres
- 1 square mile = `{{gaps|2.589|988|110|336}}`{=mediawiki} square kilometres
### Other units including historical {#other_units_including_historical}
There are several other common units for area. The are was the original unit of area in the metric system, with:
- 1 are = 100 square metres
Though the are has fallen out of use, the hectare is still commonly used to measure land:
- 1 hectare = 100 ares = 10,000 square metres = 0.01 square kilometres
Other uncommon metric units of area include the tetrad, the hectad, and the myriad.
The acre is also commonly used to measure land areas, where
- 1 acre = 4,840 square yards = 43,560 square feet.
An acre is approximately 40% of a hectare.
On the atomic scale, area is measured in units of barns, such that:
- 1 barn = 10^−28^ square meters.
The barn is commonly used in describing the cross-sectional area of interaction in nuclear physics.
In South Asia (mainly Indians), although the countries use SI units as official, many South Asians still use traditional units. Each administrative division has its own area unit, some of them have same names, but with different values. There\'s no official consensus about the traditional units values. Thus, the conversions between the SI units and the traditional units may have different results, depending on what reference that has been used.
Some traditional South Asian units that have fixed value:
- 1 Killa = 1 acre
- 1 Ghumaon = 1 acre
- 1 Kanal = 0.125 acre (1 acre = 8 kanal)
- 1 Decimal = 48.4 square yards
- 1 Chatak = 180 square feet
## History
### Circle area {#circle_area}
In the 5th century BCE, Hippocrates of Chios was the first to show that the area of a disk (the region enclosed by a circle) is proportional to the square of its diameter, as part of his quadrature of the lune of Hippocrates, but did not identify the constant of proportionality. Eudoxus of Cnidus, also in the 5th century BCE, also found that the area of a disk is proportional to its radius squared.
Subsequently, Book I of Euclid\'s *Elements* dealt with equality of areas between two-dimensional figures. The mathematician Archimedes used the tools of Euclidean geometry to show that the area inside a circle is equal to that of a right triangle whose base has the length of the circle\'s circumference and whose height equals the circle\'s radius, in his book *Measurement of a Circle*. (The circumference is 2`{{pi}}`{=mediawiki}*r*, and the area of a triangle is half the base times the height, yielding the area `{{pi}}`{=mediawiki}*r*^2^ for the disk.) Archimedes approximated the value of `{{pi}}`{=mediawiki} (and hence the area of a unit-radius circle) with his doubling method, in which he inscribed a regular triangle in a circle and noted its area, then doubled the number of sides to give a regular hexagon, then repeatedly doubled the number of sides as the polygon\'s area got closer and closer to that of the circle (and did the same with circumscribed polygons).
### Triangle area {#triangle_area}
### Quadrilateral area {#quadrilateral_area}
In the 7th century CE, Brahmagupta developed a formula, now known as Brahmagupta\'s formula, for the area of a cyclic quadrilateral (a quadrilateral inscribed in a circle) in terms of its sides. In 1842, the German mathematicians Carl Anton Bretschneider and Karl Georg Christian von Staudt independently found a formula, known as Bretschneider\'s formula, for the area of any quadrilateral.
### General polygon area {#general_polygon_area}
The development of Cartesian coordinates by René Descartes in the 17th century allowed the development of the surveyor\'s formula for the area of any polygon with known vertex locations by Gauss in the 19th century.
### Areas determined using calculus {#areas_determined_using_calculus}
The development of integral calculus in the late 17th century provided tools that could subsequently be used for computing more complicated areas, such as the area of an ellipse and the surface areas of various curved three-dimensional objects.
## Area formulas {#area_formulas}
### Polygon formulas {#polygon_formulas}
For a non-self-intersecting (simple) polygon, the Cartesian coordinates $(x_i, y_i)$ (*i*=0, 1, \..., *n*-1) of whose *n* vertices are known, the area is given by the surveyor\'s formula:
$$A = \frac{1}{2} \Biggl\vert \sum_{i = 0}^{n - 1}( x_i y_{i + 1} - x_{i + 1} y_i) \Biggr\vert$$
where when *i*=*n*-1, then *i*+1 is expressed as modulus *n* and so refers to 0.
#### Rectangles
The most basic area formula is the formula for the area of a rectangle. Given a rectangle with length `{{mvar|l}}`{=mediawiki} and width `{{mvar|w}}`{=mediawiki}, the formula for the area is:
: *lw*}} (rectangle).
That is, the area of the rectangle is the length multiplied by the width. As a special case, as `{{math|''l'' {{=}}`{=mediawiki} *w*}} in the case of a square, the area of a square with side length `{{mvar|s}}`{=mediawiki} is given by the formula:
: *s*^2^}} (square).
The formula for the area of a rectangle follows directly from the basic properties of area, and is sometimes taken as a definition or axiom. On the other hand, if geometry is developed before arithmetic, this formula can be used to define multiplication of real numbers.
#### Dissection, parallelograms, and triangles {#dissection_parallelograms_and_triangles}
Most other simple formulas for area follow from the method of dissection. This involves cutting a shape into pieces, whose areas must sum to the area of the original shape. For an example, any parallelogram can be subdivided into a trapezoid and a right triangle, as shown in figure to the left. If the triangle is moved to the other side of the trapezoid, then the resulting figure is a rectangle. It follows that the area of the parallelogram is the same as the area of the rectangle:
: *bh*}} (parallelogram).
However, the same parallelogram can also be cut along a diagonal into two congruent triangles, as shown in the figure to the right. It follows that the area of each triangle is half the area of the parallelogram:
$$A = \frac{1}{2}bh$$ (triangle). Similar arguments can be used to find area formulas for the trapezoid as well as more complicated polygons.
### Area of curved shapes {#area_of_curved_shapes}
#### Circles
`{{main article|Area of a circle}}`{=mediawiki} The formula for the area of a circle (more properly called the area enclosed by a circle or the area of a disk) is based on a similar method. Given a circle of radius `{{math|''r''}}`{=mediawiki}, it is possible to partition the circle into sectors, as shown in the figure to the right. Each sector is approximately triangular in shape, and the sectors can be rearranged to form an approximate parallelogram. The height of this parallelogram is `{{math|''r''}}`{=mediawiki}, and the width is half the circumference of the circle, or `{{math|π''r''}}`{=mediawiki}. Thus, the total area of the circle is `{{math|π''r''<sup>2</sup>}}`{=mediawiki}:
: π*r*^2^}} (circle).
Though the dissection used in this formula is only approximate, the error becomes smaller and smaller as the circle is partitioned into more and more sectors. The limit of the areas of the approximate parallelograms is exactly `{{math|π''r''<sup>2</sup>}}`{=mediawiki}, which is the area of the circle.
This argument is actually a simple application of the ideas of calculus. In ancient times, the method of exhaustion was used in a similar way to find the area of the circle, and this method is now recognized as a precursor to integral calculus. Using modern methods, the area of a circle can be computed using a definite integral:
$$A \;=\;2\int_{-r}^r \sqrt{r^2 - x^2}\,dx \;=\; \pi r^2.$$
#### Ellipses
The formula for the area enclosed by an ellipse is related to the formula of a circle; for an ellipse with semi-major and semi-minor axes `{{math|''x''}}`{=mediawiki} and `{{math|''y''}}`{=mediawiki} the formula is:
$$A = \pi xy .$$
### Non-planar surface area {#non_planar_surface_area}
Most basic formulas for surface area can be obtained by cutting surfaces and flattening them out (see: developable surfaces). For example, if the side surface of a cylinder (or any prism) is cut lengthwise, the surface can be flattened out into a rectangle. Similarly, if a cut is made along the side of a cone, the side surface can be flattened out into a sector of a circle, and the resulting area computed.
The formula for the surface area of a sphere is more difficult to derive: because a sphere has nonzero Gaussian curvature, it cannot be flattened out. The formula for the surface area of a sphere was first obtained by Archimedes in his work *On the Sphere and Cylinder*. The formula is:
: 4*πr*^2^}} (sphere),
where `{{math|''r''}}`{=mediawiki} is the radius of the sphere. As with the formula for the area of a circle, any derivation of this formula inherently uses methods similar to calculus.
### General formulas {#general_formulas}
#### Areas of 2-dimensional figures {#areas_of_2_dimensional_figures}
- A triangle: $\tfrac12Bh$ (where *B* is any side, and *h* is the distance from the line on which *B* lies to the other vertex of the triangle). This formula can be used if the height *h* is known. If the lengths of the three sides are known then *Heron\'s formula* can be used: $\sqrt{s(s-a)(s-b)(s-c)}$ where *a*, *b*, *c* are the sides of the triangle, and $s = \tfrac12(a + b + c)$ is half of its perimeter. If an angle and its two included sides are given, the area is $\tfrac12 a b \sin(C)$ where `{{math|''C''}}`{=mediawiki} is the given angle and `{{math|''a''}}`{=mediawiki} and `{{math|''b''}}`{=mediawiki} are its included sides. If the triangle is graphed on a coordinate plane, a matrix can be used and is simplified to the absolute value of $\tfrac12(x_1 y_2 + x_2 y_3 + x_3 y_1 - x_2 y_1 - x_3 y_2 - x_1 y_3)$. This formula is also known as the shoelace formula and is an easy way to solve for the area of a coordinate triangle by substituting the 3 points *(x~1~,y~1~)*, *(x~2~,y~2~)*, and *(x~3~,y~3~)*. The shoelace formula can also be used to find the areas of other polygons when their vertices are known. Another approach for a coordinate triangle is to use calculus to find the area.
- A simple polygon constructed on a grid of equal-distanced points (i.e., points with integer coordinates) such that all the polygon\'s vertices are grid points: $i + \frac{b}{2} - 1$, where *i* is the number of grid points inside the polygon and *b* is the number of boundary points. This result is known as Pick\'s theorem.
#### Area in calculus {#area_in_calculus}
- The area between a positive-valued curve and the horizontal axis, measured between two values *a* and *b* (b is defined as the larger of the two values) on the horizontal axis, is given by the integral from *a* to *b* of the function that represents the curve:
$$A = \int_a^{b} f(x) \, dx.$$
- The area between the graphs of two functions is equal to the integral of one function, *f*(*x*), minus the integral of the other function, *g*(*x*):
$$A = \int_a^{b} ( f(x) - g(x) ) \, dx,$$ where $f(x)$ is the curve with the greater y-value.
- An area bounded by a function $r = r(\theta)$ expressed in polar coordinates is:
$$A = {1 \over 2} \int r^2 \, d\theta.$$
- The area enclosed by a parametric curve $\vec u(t) = (x(t), y(t))$ with endpoints $\vec u(t_0) = \vec u(t_1)$ is given by the line integrals:
$$\oint_{t_0}^{t_1} x \dot y \, dt = - \oint_{t_0}^{t_1} y \dot x \, dt = {1 \over 2} \oint_{t_0}^{t_1} (x \dot y - y \dot x) \, dt$$
: or the *z*-component of
$${1 \over 2} \oint_{t_0}^{t_1} \vec u \times \dot{\vec u} \, dt.$$
: (For details, see `{{slink|Green's theorem|Area calculation}}`{=mediawiki}.) This is the principle of the planimeter mechanical device.
#### Bounded area between two quadratic functions {#bounded_area_between_two_quadratic_functions}
To find the bounded area between two quadratic functions, we first subtract one from the other, writing the difference as $f(x)-g(x)=ax^2+bx+c=a(x-\alpha)(x-\beta)$ where *f*(*x*) is the quadratic upper bound and *g*(*x*) is the quadratic lower bound. By the area integral formulas above and Vieta\'s formula, we can obtain that $A=\frac{(b^2-4ac)^{3/2}}{6a^2}=\frac{a}{6}(\beta-\alpha)^3,\qquad a\neq0.$ The above remains valid if one of the bounding functions is linear instead of quadratic.
#### Surface area of 3-dimensional figures {#surface_area_of_3_dimensional_figures}
- Cone: $\pi r\left(r + \sqrt{r^2 + h^2}\right)$, where *r* is the radius of the circular base, and *h* is the height. That can also be rewritten as $\pi r^2 + \pi r l$ or $\pi r (r + l) \,\!$ where *r* is the radius and *l* is the slant height of the cone. $\pi r^2$ is the base area while $\pi r l$ is the lateral surface area of the cone.
- Cube: $6s^2$, where *s* is the length of an edge.
- Cylinder: $2\pi r(r + h)$, where *r* is the radius of a base and *h* is the height. The $2\pi r$ can also be rewritten as $\pi d$, where *d* is the diameter.
- Prism: $2B + Ph$, where *B* is the area of a base, *P* is the perimeter of a base, and *h* is the height of the prism.
- pyramid: $B + \frac{PL}{2}$, where *B* is the area of the base, *P* is the perimeter of the base, and *L* is the length of the slant.
- Rectangular prism: $2 (\ell w + \ell h + w h)$, where $\ell$ is the length, *w* is the width, and *h* is the height.
#### General formula for surface area {#general_formula_for_surface_area}
The general formula for the surface area of the graph of a continuously differentiable function $z=f(x,y),$ where $(x,y)\in D\subset\mathbb{R}^2$ and $D$ is a region in the xy-plane with the smooth boundary:
: $A=\iint_D\sqrt{\left(\frac{\partial f}{\partial x}\right)^2+\left(\frac{\partial f}{\partial y}\right)^2+1}\,dx\,dy.$
An even more general formula for the area of the graph of a parametric surface in the vector form $\mathbf{r}=\mathbf{r}(u,v),$ where $\mathbf{r}$ is a continuously differentiable vector function of $(u,v)\in D\subset\mathbb{R}^2$ is:
: $A=\iint_D \left|\frac{\partial\mathbf{r}}{\partial u}\times\frac{\partial\mathbf{r}}{\partial v}\right|\,du\,dv.$
### List of formulas {#list_of_formulas}
+------------------------+--------------------------------------------------------------------+--------------------------------------------------------+
| Shape | Formula | Variables |
+========================+====================================================================+========================================================+
| Square | $A=s^2$ | |
+------------------------+--------------------------------------------------------------------+--------------------------------------------------------+
| Rectangle | $A=ab$ | |
+------------------------+--------------------------------------------------------------------+--------------------------------------------------------+
| Triangle | $A=\frac12bh \,\!$ | |
+------------------------+--------------------------------------------------------------------+--------------------------------------------------------+
| Triangle | $A=\frac12 a b \sin(\gamma)\,\!$ | |
+------------------------+--------------------------------------------------------------------+--------------------------------------------------------+
| Triangle\ | $A=\sqrt{s(s-a)(s-b)(s-c)}\,\!$ | $s =\tfrac 1 2 (a+b+c)$ |
| (Heron\'s formula) | | |
+------------------------+--------------------------------------------------------------------+--------------------------------------------------------+
| Isosceles triangle | $A=\frac{c}{4}\sqrt{4a^2-c^2}$ | |
+------------------------+--------------------------------------------------------------------+--------------------------------------------------------+
| Regular triangle\ | $A=\frac{\sqrt{3}}{4}a^2\,\!$ | |
| (equilateral triangle) | | |
+------------------------+--------------------------------------------------------------------+--------------------------------------------------------+
| Rhombus/Kite | $A=\frac12de$ | |
+------------------------+--------------------------------------------------------------------+--------------------------------------------------------+
| Parallelogram | $A=ah_a\,\!$ | |
+------------------------+--------------------------------------------------------------------+--------------------------------------------------------+
| Trapezoid | $A=\frac{(a+c)h}{2} \,\!$ | |
+------------------------+--------------------------------------------------------------------+--------------------------------------------------------+
| Regular hexagon | $A=\frac{3}{2} \sqrt{3}a^2\,\!$ | |
+------------------------+--------------------------------------------------------------------+--------------------------------------------------------+
| Regular octagon | $A=2(1+\sqrt{2})a^2\,\!$ | |
+------------------------+--------------------------------------------------------------------+--------------------------------------------------------+
| Regular polygon\ | $A=n\frac{ar}{2}=\frac{pr}{2}$\ | $p=na\$ (perimeter)\ |
| ($n$ sides) | $\quad =\tfrac 1 4 na^2\cot(\tfrac \pi n)$\ | $r=\tfrac a 2 \cot(\tfrac \pi n),$\ |
| | $\quad = nr^2 \tan(\tfrac \pi n)$\ | $\tfrac a 2= r\tan(\tfrac \pi n)=R\sin(\tfrac \pi n)$\ |
| | $\quad =\tfrac{1}{4n}p^2\cot(\tfrac \pi n)$\ | $r:$ incircle radius\ |
| | $\quad =\tfrac{1}{2}nR^2 \sin(\tfrac{2\pi}{n}) \,\!$ | $R:$ circumcircle radius |
+------------------------+--------------------------------------------------------------------+--------------------------------------------------------+
| Circle | $A=\pi r^2=\frac{\pi d^2}{4}$\ | 100px |
| | ($d=2r:$ diameter) | |
+------------------------+--------------------------------------------------------------------+--------------------------------------------------------+
| Circular sector | $A=\frac{\theta}{2}r^2=\frac{L \cdot r}{2}\,\!$ | |
+------------------------+--------------------------------------------------------------------+--------------------------------------------------------+
| Ellipse | $A=\pi ab \,\!$ | |
+------------------------+--------------------------------------------------------------------+--------------------------------------------------------+
| Integral | $A=\int_a^b f(x)\mathrm{d}x ,\ f(x)\ge 0$ | |
+------------------------+--------------------------------------------------------------------+--------------------------------------------------------+
| | **Surface area** | |
+------------------------+--------------------------------------------------------------------+--------------------------------------------------------+
| Sphere\ | $A = 4\pi r^2 = \pi d^2$ | |
+------------------------+--------------------------------------------------------------------+--------------------------------------------------------+
| Cuboid | $A = 2(ab+ac+bc)$ | |
+------------------------+--------------------------------------------------------------------+--------------------------------------------------------+
| Cylinder\ | $A = 2 \pi r (r + h)$ | |
| (incl. bottom and top) | | |
+------------------------+--------------------------------------------------------------------+--------------------------------------------------------+
| Cone\ | $A = \pi r (r + \sqrt{r^2+h^2})$ | |
| (incl. bottom) | | |
+------------------------+--------------------------------------------------------------------+--------------------------------------------------------+
| Torus | $A = 4\pi^2 \cdot R \cdot r$ | |
+------------------------+--------------------------------------------------------------------+--------------------------------------------------------+
| Surface of revolution | $A = 2\pi\int_a^b\! f(x)\sqrt{1+\left[f'(x)\right]^2}\mathrm{d}x$\ | |
| | (rotation around the x-axis) | |
+------------------------+--------------------------------------------------------------------+--------------------------------------------------------+
| | | |
+------------------------+--------------------------------------------------------------------+--------------------------------------------------------+
: Additional common formulas for area:
The above calculations show how to find the areas of many common shapes.
The areas of irregular (and thus arbitrary) polygons can be calculated using the \"Surveyor\'s formula\" (shoelace formula).
### Relation of area to perimeter {#relation_of_area_to_perimeter}
The isoperimetric inequality states that, for a closed curve of length *L* (so the region it encloses has perimeter *L*) and for area *A* of the region that it encloses,
$$4\pi A \le L^2,$$
and equality holds if and only if the curve is a circle. Thus a circle has the largest area of any closed figure with a given perimeter.
At the other extreme, a figure with given perimeter *L* could have an arbitrarily small area, as illustrated by a rhombus that is \"tipped over\" arbitrarily far so that two of its angles are arbitrarily close to 0° and the other two are arbitrarily close to 180°.
For a circle, the ratio of the area to the circumference (the term for the perimeter of a circle) equals half the radius *r*. This can be seen from the area formula *πr*^2^ and the circumference formula 2*πr*.
The area of a regular polygon is half its perimeter times the apothem (where the apothem is the distance from the center to the nearest point on any side).
### Fractals
Doubling the edge lengths of a polygon multiplies its area by four, which is two (the ratio of the new to the old side length) raised to the power of two (the dimension of the space the polygon resides in). But if the one-dimensional lengths of a fractal drawn in two dimensions are all doubled, the spatial content of the fractal scales by a power of two that is not necessarily an integer. This power is called the fractal dimension of the fractal.
## Area bisectors {#area_bisectors}
There are an infinitude of lines that bisect the area of a triangle. Three of them are the medians of the triangle (which connect the sides\' midpoints with the opposite vertices), and these are concurrent at the triangle\'s centroid; indeed, they are the only area bisectors that go through the centroid. Any line through a triangle that splits both the triangle\'s area and its perimeter in half goes through the triangle\'s incenter (the center of its incircle). There are either one, two, or three of these for any given triangle.
Any line through the midpoint of a parallelogram bisects the area.
All area bisectors of a circle or other ellipse go through the center, and any chords through the center bisect the area. In the case of a circle they are the diameters of the circle.
## Optimization
Given a wire contour, the surface of least area spanning (\"filling\") it is a minimal surface. Familiar examples include soap bubbles.
The question of the filling area of the Riemannian circle remains open.
The circle has the largest area of any two-dimensional object having the same perimeter.
A cyclic polygon (one inscribed in a circle) has the largest area of any polygon with a given number of sides of the same lengths.
A version of the isoperimetric inequality for triangles states that the triangle of greatest area among all those with a given perimeter is equilateral.
The triangle of largest area of all those inscribed in a given circle is equilateral; and the triangle of smallest area of all those circumscribed around a given circle is equilateral.
The ratio of the area of the incircle to the area of an equilateral triangle, $\frac{\pi}{3\sqrt{3}}$, is larger than that of any non-equilateral triangle.
The ratio of the area to the square of the perimeter of an equilateral triangle, $\frac{1}{12\sqrt{3}},$ is larger than that for any other triangle.
| 2025-08-01T00:00:00 |
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Actaeon
|
In Greek mythology, **Actaeon** (`{{IPAc-en|æ|k|ˈ|t|iː|ə|n}}`{=mediawiki}; *Ἀκταίων\]\]* *Aktaiōn*) was the son of the priestly herdsman Aristaeus and Autonoe in Boeotia, and a famous Theban hero. Through his mother he was a member of the ruling House of Cadmus. Like Achilles, in a later generation, he was trained by the centaur Chiron.
He fell to the fatal wrath of Artemis (later his myth was attached to her Roman counterpart Diana), but the surviving details of his transgression vary: \"the only certainty is in what Aktaion suffered, his pathos, and what Artemis did: the hunter became the hunted; he was transformed into a stag, and his raging hounds, struck with a \'wolf\'s frenzy\' (Lyssa), tore him apart as they would a stag.\"
The many depictions both in ancient art and in the Renaissance and post-Renaissance art normally show either the moment of transgression and transformation, or his death by his own hounds.
## Story
Among others, John Heath has observed, \"The unalterable kernel of the tale was a hunter\'s transformation into a deer and his death in the jaws of his hunting dogs. But authors were free to suggest different motives for his death.\" In the version that was offered by the Hellenistic poet Callimachus, which has become the standard setting, Artemis was bathing in the woods when the hunter Actaeon stumbled across her, thus seeing her naked. He stopped and stared, amazed at her ravishing beauty. Once seen, Artemis got revenge on Actaeon: she forbade him speech -- if he tried to speak, he would be changed into a stag -- for the unlucky profanation of her virginity\'s mystery.
\[\[<File:Jean> Mignon - The Transformation of Actaeon - Google Art Project.jpg\|thumb\|*The Transformation of Actaeon*, etching by Jean Mignon, 430 x 574 mm, 1550s?, without its very elaborate frame. Actaeon is shown three times, finally being killed by his hounds.
with frame\]\]
Upon hearing the call of his hunting party, he cried out to them and immediately transformed. At this, he fled deep into the woods, and doing so he came upon a pond and, seeing his reflection, groaned. His own hounds then turned upon him and pursued him, not recognizing him. In an endeavour to save himself, he raised his eyes (and would have raised his arms, had he had them) toward Mount Olympus. The gods did not heed his desperation, and he was torn to pieces. An element of the earlier myth made Actaeon the familiar hunting companion of Artemis, no stranger. In an embroidered extension of the myth, the hounds were so upset with their master\'s death, that Chiron made a statue so lifelike that the hounds thought it was Actaeon.
There are various other versions of his transgression: The Hesiodic *Catalogue of Women* and pseudo-Apollodoran *Bibliotheke* state that his offense was that he was a rival of Zeus for Semele, his mother\'s sister, whereas in Euripides\' *Bacchae* he has boasted that he is a better hunter than Artemis:
+------+--------------------------------------------------------+
| : | : Look at Actaeon\'s wretched fate |
| | : who by the man-eating hounds he had raised, |
| : | : was torn apart, better at hunting |
| | : than Artemis he had boasted to be, in the meadows. |
| : | |
| | |
| : | |
+------+--------------------------------------------------------+
Further materials, including fragments that belong with the Hesiodic *Catalogue of Women* and at least four Attic tragedies, including a *Toxotides* of Aeschylus, have been lost. Diodorus Siculus (4.81.4), in a variant of Actaeon\'s *hubris* that has been largely ignored, has it that Actaeon wanted to marry Artemis. Other authors say the hounds were Artemis\' own; some lost elaborations of the myth seem to have given them all names and narrated their wanderings after his loss. A number of ancient Greek vases depicting the metamorphosis and death of Actaeon include the goddess Lyssa in the scene, infecting his dogs with rabies and setting them against him.
According to the Latin version of the story told by the Roman Ovid having accidentally seen Diana (Artemis) on Mount Cithaeron while she was bathing, he was changed by her into a stag, and pursued and killed by his fifty hounds. This version also appears in Callimachus\' Fifth Hymn, as a mythical parallel to the blinding of Tiresias after he sees Athena bathing. The literary testimony of Actaeon\'s myth is largely lost, but Lamar Ronald Lacy, deconstructing the myth elements in what survives and supplementing it by iconographic evidence in late vase-painting, made a plausible reconstruction of an ancient Actaeon myth that Greek poets may have inherited and subjected to expansion and dismemberment. His reconstruction opposes a too-pat consensus that has an archaic Actaeon aspiring to Semele, a classical Actaeon boasting of his hunting prowess and a Hellenistic Actaeon glimpsing Artemis\' bath. Lacy identifies the site of Actaeon\'s transgression as a spring sacred to Artemis at Plataea where Actaeon was a *hero archegetes* (\"hero-founder\") The righteous hunter, the companion of Artemis, seeing her bathing naked in the spring, was moved to try to make himself her consort, as Diodorus Siculus noted, and was punished, in part for transgressing the hunter\'s \"ritually enforced deference to Artemis\" (Lacy 1990:42).
## Names of dogs {#names_of_dogs}
Dogs Source
------------------------ -------- --------- ----------------
*Apollodorus* *Ovid* Hyginus
*Ovid* *Other author*
Acamas
Aethon
Agrius
Amarynthus ✓
Arcas ?
Argiodus (Towser) ✓ ✓
Asbolos (Sooty) ✓ ✓
Balius (Dappled) ✓
Borax
Bores ✓
Boreas
Charops
Corus
Cyllopodes
Cyprius ?
Dorceus (Quicksight) ✓ ✓
Draco
Dromas (Racer) ✓ ✓
Dromius
Echnobas ?
Elion ?
Gnosius ?
Eudromus
Haemon
Harpalicus
Harpalos (Snap) ✓ ✓
Hylactor (Babbler) ✓ ✓
Hylaeus (Woodranger) ✓ ✓
Ichneus
Ichnobates (Tracer) ✓ ✓
Labros (Wildtooth) ✓ ✓
Lacon ✓ ✓
Ladon ✓ ✓
Laelaps (Hunter) ✓ ✓
Lampus
Leon
Leucon (Blanche) ✓ ✓
Lynceus ✓
Machimus
Melampus (Blackfoot) ✓ ✓
Melaneus (Blackcoat) ✓ ✓
Obrimus
Ocydromus
Ocythous
Omargus ✓
Nebrophonos (Killbuck) ✓ ✓
Oribasos (Surefoot) ✓ ✓
Pachylus
Pamphagos (Glutton) ✓ ✓
Pterelas (Wingfoot) ✓ ✓
Spartus ✓
Stilbon
Syrus
Theron (Tempest) ✓ ✓
Thoos (Quickfoot) ✓ ✓
Tigris (Tiger) ✓ ✓
Zephyrus
Number 6 22 27
: List of Actaeon\'s dogs
Notes:
- Names of dogs were verified to correspond to the list given in Ovid\'s text where the names were already transliterated.
- ? = Seven listed names of dogs in Hyginus\' *Fabulae*, was probably misread or misinterpreted by later authors because it does not correspond to the exact numbers and names given by Ovid:
- *Arcas* signifies Arcadia, place of origin of three dogs namely Pamphagos, Dorceus and Oribasus
- *Cyprius* means Cyprus, where the dogs Lysisca and Harpalos originated
- *Gnosius* can be read as Knossus in Crete, which signify that Ichnobates was a Knossian breed of dog
- *Echnobas*, *Elion*, *Aura* and *Therodanapis* were probably place names or adjectives defining the characteristics of dogs
## The \"bed of Actaeon\" {#the_bed_of_actaeon}
In the second century AD, the traveller Pausanias was shown a spring on the road in Attica leading to Plataea from Eleutherae, just beyond Megara \"and a little farther on a rock. It is called the bed of Actaeon, for it is said that he slept thereon when weary with hunting and that into this spring he looked while Artemis was bathing in it.\"
\"As to Actæon there is a tradition at Orchomenus, that a spectre which sat on a stone injured their land. And when they consulted the oracle at Delphi, the god bade them bury in the ground whatever remains they could find of Actæon: he also bade them to make a brazen copy of the spectre and fasten it with iron to the stone. This I have myself seen, and they annually offer funeral rites to Actæon.\"
## Parallels in Akkadian and Ugarit poems {#parallels_in_akkadian_and_ugarit_poems}
In the standard version of the *Epic of Gilgamesh* (tablet vi) there is a parallel, in the series of examples Gilgamesh gives Ishtar of her mistreatment of her serial lovers:
> You loved the herdsman, shepherd and chief shepherd\
> Who was always heaping up the glowing ashes for you,\
> And cooked ewe-lambs for you every day.\
> But you hit him and turned him into a wolf,\
> His own herd-boys hunt him down\
> And his dogs tear at his haunches.
Actaeon, torn apart by dogs incited by Artemis, finds another Near Eastern parallel in the Ugaritic hero Aqht, torn apart by eagles incited by Anath who wanted his hunting bow.
The virginal Artemis of classical times is not directly comparable to Ishtar of the many lovers, but the mytheme of Artemis shooting Orion, was linked to her punishment of Actaeon by T.C.W. Stinton; the Greek context of the mortal\'s reproach to the amorous goddess is translated to the episode of Anchises and Aphrodite. Daphnis too was a herdsman loved by a goddess and punished by her: see Theocritus\' First Idyll.
## Symbolism regarding Actaeon {#symbolism_regarding_actaeon}
In Greek Mythology, Actaeon is widely thought to symbolize ritual human sacrifice in attempt to please a God or Goddess: the dogs symbolize the sacrificers and Actaeon symbolizes the sacrifice.
Actaeon may symbolize human curiosity or irreverence.
The myth is seen by Jungian psychologist Wolfgang Giegerich as a symbol of spiritual transformation and/or enlightenment.
Actaeon often symbolizes a cuckold, as when he is turned into a stag, he becomes \"horned\". This is alluded to in Shakespeare\'s *Merry Wives*, Robert Burton\'s *Anatomy of Melancholy*, and others.
## Cultural depictions {#cultural_depictions}
The two main scenes are Actaeon surprising Artemis/Diana, and his death. In classical art Actaeon is normally shown as fully human, even as his hounds are killing him (sometimes he has small horns), but in Renaissance art he is often given a deer\'s head with antlers even in the scene with Diana, and by the time he is killed he has at the least this head, and has often completely transformed into the shape of a deer.
- Aeschylus and other tragic poets made use of the story, which was a favourite subject in ancient works of art.
- There is a well-known small marble group in the British Museum illustrative of the story, in gallery 83/84.
- Two paintings by the 16th century painter Titian (*Death of Actaeon* and *Diana and Actaeon*).
- *Actéon*, an operatic pastorale by Marc-Antoine Charpentier.
- Percy Bysshe Shelley suggests a parallel between his alter-ego and Actaeon in his elegy for John Keats, *Adonais*, stanza 31 (\'\[he\] had gazed on Nature\'s naked loveliness/ Actaeon-like, and now he fled astray/ \.../ And his own thoughts, along that rugged way,/ Pursued, like raging hounds, their father and their prey.\')
- The aria \"Oft she visits this lone mountain\" from Purcell\'s *Dido and Aeneas*, first performed in 1689 or earlier.
- Giordano Bruno, *Gli Eroici Furori*.
- In canto V of Giambattista Marino\'s poem Adone the protagonist goes to theater to see a tragedy representing the myth of Actaeon. This episode foreshadows the protagonist\'s violent death at the end of the book.
- In Act I Scene 2 of Jacques Offenbach\'s *Orpheus in the Underworld*, Actaeon is Diana (Artemis)\'s lover, and it is Jupiter who turns him into a stag, which puts Diana off hunting. His story is relinquished at this point, in favour of the other plots.
- Ted Hughes wrote a version of the story in his *Tales from Ovid*.
- Diane and Actéon Pas de Deux from Marius Petipa\'s ballet, *Le Roi Candaule*, to the music by Riccardo Drigo and Cesare Pugni, later incorporated into the second act of *La Esmeralda (ballet)*.
- In *Twelfth Night* by William Shakespeare, Orsino compares his unrequited love for Olivia to the fate of Actaeon. \"O, when mine eyes did see Olivia first, Methought she purged the air of pestilence, That instant was I turned into a hart, and my desires like fell and cruel hounds e\'er since pursue me.\" Act 1 Scene 1.
- In Christopher Marlowe\'s play *Edward II*, courtier Piers Gaveston seeks to entertain his lover, King Edward II of England, by presenting a play based on the Actaeon myth. In Gaveston\'s version, Diane is played by a naked boy holding an olive branch to hide his loins, and it is the boy-Diane who transforms Actaeon into a hart and lets him be devoured by the hounds. Thus, Gaveston\'s (and Marlowe\'s) interpretation adds a strong element of homoeroticism, absent from the original myth.
- Paul Manship in 1925 created a set of copper statute of Diane and Actaeon, which in the Luce Lunder Smithsonian Institution.
- French based collective LFKs and his film/theatre director, writer and visual artist Jean Michel Bruyere produced a series of 600 shorts and \"medium\" films, an interactive 360° installation, *Si poteris narrare licet* (\"if you are able to speak of it, then you may do so\") in 2002, a 3D 360° installation *La Dispersion du Fils* (from 2008 to 2016) and an outdoor performance, *Une Brutalité pastorale* (2000) all about the myth of Diana and Actaeon.
- In Matthew Barney\'s 2019 movie *Redoubt* set in the Sawtooth Mountains of the U.S. state of Idaho and an accompanying traveling art exhibition originating at the Yale University Art Gallery the myth is retold by the visual artist and filmmaker via avenues of his own design.
- Seamus Heaney\'s collection *North* contains an aisling concerning the myth of Diana and Actaeon.
## Royal House of Thebes family tree {#royal_house_of_thebes_family_tree}
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1,223 |
Telecommunications in Anguilla
|
This article is about communications systems in Anguilla.
## Telephone
**Telephones -- main lines in use:** 6,200 (2002)
: *country comparison to the world:* 212
**Telephones -- mobile cellular:** 1,800 (2002)
: *country comparison to the world:* 211
**Telephone system:**\
*Domestic:* Modern internal telephone system\
*International:* EAST CARIBBEAN FIBRE SYSTEM ECFS (cable system)\
*microwave radio relay to island of Saint Martin (Guadeloupe and Netherlands Antilles)*
## Mobile phone (GSM) {#mobile_phone_gsm}
**Mobile phone operators:\
** FLOW (Anguilla) Ltd. -- GSM and UMTS 850 and 1900 MHz, LTE 700 MHz with Island-wide coverage \
Digicel (Anguilla) Ltd. -- GSM and UMTS 850 to 1900 MHz, LTE 700 MHz
**Mobiles:** ? (2007)
## Radio
**Radio broadcast stations:** AM 3, FM 7, shortwave 0 (2007)
Band / Freq. Call Sign Brand City of licence Notes
-------------- ----------- --------------------------------------- ----------------- ----------------------------------------
AM 690 kHz Unknown Caribbean Beacon The Valley Religious broadcaster
AM 1500 kHz Unknown Caribbean Beacon The Valley 2.5 kW repeater
AM 1610 kHz Unknown Caribbean Beacon The Valley 200 kW repeater
FM 92.9 MHz Unknown Klass 92.9 The Valley
FM 93.3 MHz Unknown Rainbow FM The Valley Caribbean Music, News
FM 95.5 MHz Unknown Radio Anguilla The Valley Public broadcaster
FM 97.7 MHz Unknown Heart Beat Radio/Up Beat Radio The Valley 30 kW, Caribbean Music, News
FM 99.3 MHz ZNBR-FM NBR -- New Beginning Radio / Grace FM The Valley 5 kW, Religious broadcaster
FM 100.1 MHz Unknown Caribbean Beacon The Valley Religious broadcaster
FM 100.9 MHz Unknown CBN -- Country Broadcast Network The Valley 3 kW
FM 103.3 MHz Unknown Kool FM The Valley Religious broadcaster, Urban Caribbean
FM 105.1 MHz ZRON-FM Tradewinds Radio The Valley 5 kW, Caribbean Music, News
FM 106.7 MHz unknown VOC -- Voice Of Creation Sachasses Religious broadcaster
FM 107.9 MHz unknown GEM Radio Network The Valley Repeater (Trinidad)
SW 6090 kHz Unknown Caribbean Beacon The Valley Religious
SW 11775 kHz Unknown Caribbean Beacon The Valley Religious
: Radio Stations of Anguilla
**Radios:** 3,000 (1997)
## Television
**Television broadcast stations:** 1 (1997)
**Televisions:** 1,000 (1997)
## Internet
**Internet country code:** .ai (Top level domain)
**Internet Service Providers (ISPs):** 2 (FLOW -- [1](https://archive.today/20200404133519/https://discoverflow.co/anguilla/), Digicel Anguilla -- [2](https://www.digicelgroup.com/ai/en.html) )
**Internet hosts:** 269 (2012)
: *country comparison to the world:* 192
**Internet:** users: 12,377 (2018)
: *country comparison to the world:* 206
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1,234 |
Acoustic theory
|
**Acoustic theory** is a scientific field that relates to the description of sound waves. It derives from fluid dynamics. See acoustics for the engineering approach.
For sound waves of any magnitude of a disturbance in velocity, pressure, and density we have
:
` \begin{align}`\
` \frac{\partial \rho'}{\partial t} +\rho_0\nabla\cdot \mathbf{v} + \nabla\cdot(\rho'\mathbf{v}) & = 0 \qquad \text{(Conservation of Mass)} \\`\
` (\rho_0+\rho')\frac{\partial \mathbf{v}}{\partial t} + (\rho_0+\rho')(\mathbf{v}\cdot\nabla)\mathbf{v} + \nabla p' & = 0 \qquad \text{(Equation of Motion)}`\
` \end{align}`
In the case that the fluctuations in velocity, density, and pressure are small, we can approximate these as
:
` \begin{align}`\
` \frac{\partial \rho'}{\partial t} +\rho_0\nabla\cdot \mathbf{v} & = 0 \\`\
` \frac{\partial \mathbf{v}}{\partial t} + \frac{1}{\rho_0}\nabla p'& = 0`\
` \end{align}`
Where $\mathbf{v}(\mathbf{x},t)$ is the perturbed velocity of the fluid, $p_0$ is the pressure of the fluid at rest, $p'(\mathbf{x},t)$ is the perturbed pressure of the system as a function of space and time, $\rho_0$ is the density of the fluid at rest, and $\rho'(\mathbf{x}, t)$ is the variance in the density of the fluid over space and time.
In the case that the velocity is irrotational ($\nabla\times \mathbf{v} = 0$), we then have the acoustic wave equation that describes the system:
$$\frac{1}{c^2}\frac{\partial^2 \phi}{\partial t^2} - \nabla^2\phi = 0$$
Where we have
$$\begin{align}
\mathbf{v} & = -\nabla \phi \\
c^2 & = (\frac{\partial p}{\partial \rho})_s\\
p' & = \rho_0\frac{\partial \phi}{\partial t}\\
\rho' & = \frac{\rho_0}{c^2}\frac{\partial \phi}{\partial t}
\end{align}$$
## Derivation for a medium at rest {#derivation_for_a_medium_at_rest}
Starting with the Continuity Equation and the Euler Equation:
:
` \begin{align}`\
` \frac{\partial \rho}{\partial t} +\nabla\cdot \rho\mathbf{v} & = 0 \\`\
` \rho\frac{\partial \mathbf{v}}{\partial t} + \rho(\mathbf{v}\cdot\nabla)\mathbf{v} + \nabla p & = 0`\
` \end{align}`
If we take small perturbations of a constant pressure and density:
:
` \begin{align}`\
` \rho & = \rho_0+\rho' \\`\
` p & = p_0 + p'`\
` \end{align}`
Then the equations of the system are
:
` \begin{align}`\
` \frac{\partial}{\partial t}(\rho_0+\rho') +\nabla\cdot (\rho_0+\rho')\mathbf{v} & = 0 \\`\
` (\rho_0+\rho')\frac{\partial \mathbf{v}}{\partial t} + (\rho_0+\rho')(\mathbf{v}\cdot\nabla)\mathbf{v} + \nabla (p_0+p') & = 0`\
` \end{align}`
Noting that the equilibrium pressures and densities are constant, this simplifies to
:
` \begin{align}`\
` \frac{\partial \rho'}{\partial t} +\rho_0\nabla\cdot\mathbf{v}+\nabla\cdot \rho'\mathbf{v} & = 0 \\`\
` (\rho_0+\rho')\frac{\partial \mathbf{v}}{\partial t} + (\rho_0+\rho')(\mathbf{v}\cdot\nabla)\mathbf{v} + \nabla p' & = 0`\
` \end{align}`
### A Moving Medium {#a_moving_medium}
Starting with
:
` \begin{align}`\
` \frac{\partial \rho'}{\partial t} +\rho_0\nabla\cdot\mathbf{w}+\nabla\cdot \rho'\mathbf{w} & = 0 \\`\
` (\rho_0+\rho')\frac{\partial \mathbf{w}}{\partial t} + (\rho_0+\rho')(\mathbf{w}\cdot\nabla)\mathbf{w} + \nabla p' & = 0`\
` \end{align}`
We can have these equations work for a moving medium by setting $\mathbf{w} = \mathbf{u} + \mathbf{v}$, where $\mathbf{u}$ is the constant velocity that the whole fluid is moving at before being disturbed (equivalent to a moving observer) and $\mathbf{v}$ is the fluid velocity.
In this case the equations look very similar:
:
` \begin{align}`\
` \frac{\partial \rho'}{\partial t} +\rho_0\nabla\cdot\mathbf{v}+\mathbf{u}\cdot\nabla\rho' + \nabla\cdot \rho'\mathbf{v} & = 0 \\`\
` (\rho_0+\rho')\frac{\partial \mathbf{v}}{\partial t} + (\rho_0+\rho')(\mathbf{u}\cdot\nabla)\mathbf{v} + (\rho_0+\rho')(\mathbf{v}\cdot\nabla)\mathbf{v} + \nabla p' & = 0`\
` \end{align}`
Note that setting $\mathbf{u} = 0$ returns the equations at rest.
## Linearized Waves {#linearized_waves}
Starting with the above given equations of motion for a medium at rest:
:
` \begin{align}`\
` \frac{\partial \rho'}{\partial t} +\rho_0\nabla\cdot\mathbf{v}+\nabla\cdot \rho'\mathbf{v} & = 0 \\`\
` (\rho_0+\rho')\frac{\partial \mathbf{v}}{\partial t} + (\rho_0+\rho')(\mathbf{v}\cdot\nabla)\mathbf{v} + \nabla p' & = 0`\
` \end{align}`
Let us now take $\mathbf{v},\rho',p'$ to all be small quantities.
In the case that we keep terms to first order, for the continuity equation, we have the $\rho'\mathbf{v}$ term going to 0. This similarly applies for the density perturbation times the time derivative of the velocity. Moreover, the spatial components of the material derivative go to 0. We thus have, upon rearranging the equilibrium density:
:
` \begin{align}`\
` \frac{\partial \rho'}{\partial t} +\rho_0\nabla\cdot \mathbf{v} & = 0 \\`\
` \frac{\partial \mathbf{v}}{\partial t} + \frac{1}{\rho_0}\nabla p' & = 0`\
` \end{align}`
Next, given that our sound wave occurs in an ideal fluid, the motion is adiabatic, and then we can relate the small change in the pressure to the small change in the density by
:
` p' = \left(\frac{\partial p}{\partial \rho_{0}}\right)_{s}\rho'`
Under this condition, we see that we now have
:
` \begin{align}`\
` \frac{\partial p'}{\partial t} +\rho_{0}\left(\frac{\partial p}{\partial \rho_0}\right)_{s}\nabla\cdot \mathbf{v} & = 0 \\`\
` \frac{\partial \mathbf{v}}{\partial t} + \frac{1}{\rho_0}\nabla p' & = 0`\
` \end{align}`
Defining the speed of sound of the system:
:
c \\equiv \\sqrt{\\left(\\frac{\\partial p}{\\partial \\rho\_{0}}\\right)\_{s}}
Everything becomes
:
` \begin{align}`\
` \frac{\partial p'}{\partial t} +\rho_0c^2\nabla\cdot \mathbf{v} & = 0 \\`\
` \frac{\partial \mathbf{v}}{\partial t} + \frac{1}{\rho_0}\nabla p' & = 0`\
` \end{align}`
### For Irrotational Fluids {#for_irrotational_fluids}
In the case that the fluid is irrotational, that is $\nabla\times\mathbf{v} = 0$, we can then write $\mathbf{v} = -\nabla\phi$ and thus write our equations of motion as
:
` \begin{align}`\
` \frac{\partial p'}{\partial t} -\rho_0c^2\nabla^2\phi & = 0 \\`\
` -\nabla\frac{\partial\phi}{\partial t} + \frac{1}{\rho_0}\nabla p' & = 0`\
` \end{align}`
The second equation tells us that
:
` p' = \rho_0 \frac{\partial \phi}{\partial t}`
And the use of this equation in the continuity equation tells us that
:
` \rho_0\frac{\partial^2 \phi}{\partial t} -\rho_0c^2\nabla^2\phi = 0`
This simplifies to
:
` \frac{1}{c^2}\frac{\partial^2 \phi}{\partial t^2} -\nabla^2\phi = 0`
Thus the velocity potential $\phi$ obeys the wave equation in the limit of small disturbances. The boundary conditions required to solve for the potential come from the fact that the velocity of the fluid must be 0 normal to the fixed surfaces of the system.
Taking the time derivative of this wave equation and multiplying all sides by the unperturbed density, and then using the fact that $p' = \rho_0 \frac{\partial \phi}{\partial t}$ tells us that
:
` \frac{1}{c^2}\frac{\partial^2 p'}{\partial t^2} -\nabla^2p' = 0`
Similarly, we saw that $p' = \left(\frac{\partial p}{\partial \rho_{0}}\right)_{s}\rho' = c^{2}\rho'$. Thus we can multiply the above equation appropriately and see that
:
` \frac{1}{c^2}\frac{\partial^2 \rho'}{\partial t^2} -\nabla^2\rho' = 0`
Thus, the velocity potential, pressure, and density all obey the wave equation. Moreover, we only need to solve one such equation to determine all other three. In particular, we have
:
` \begin{align}`\
` \mathbf{v} & = -\nabla \phi \\`\
` p' & = \rho_0 \frac{\partial \phi}{\partial t}\\`
\\rho\' & = \\frac{\\rho_0}{c\^2}\\frac{\\partial\\phi}{\\partial t}
` \end{align}`
### For a moving medium {#for_a_moving_medium}
Again, we can derive the small-disturbance limit for sound waves in a moving medium. Again, starting with
:
` \begin{align}`\
` \frac{\partial \rho'}{\partial t} +\rho_0\nabla\cdot\mathbf{v}+\mathbf{u}\cdot\nabla\rho' + \nabla\cdot \rho'\mathbf{v} & = 0 \\`\
` (\rho_0+\rho')\frac{\partial \mathbf{v}}{\partial t} + (\rho_0+\rho')(\mathbf{u}\cdot\nabla)\mathbf{v} + (\rho_0+\rho')(\mathbf{v}\cdot\nabla)\mathbf{v} + \nabla p' & = 0`\
` \end{align}`
We can linearize these into
:
` \begin{align}`\
` \frac{\partial \rho'}{\partial t} +\rho_0\nabla\cdot\mathbf{v}+\mathbf{u}\cdot\nabla\rho' & = 0 \\`\
` \frac{\partial \mathbf{v}}{\partial t} + (\mathbf{u}\cdot\nabla)\mathbf{v} + \frac{1}{\rho_0}\nabla p' & = 0`\
` \end{align}`
#### For Irrotational Fluids in a Moving Medium {#for_irrotational_fluids_in_a_moving_medium}
Given that we saw that
:
` \begin{align}`\
` \frac{\partial \rho'}{\partial t} +\rho_0\nabla\cdot\mathbf{v}+\mathbf{u}\cdot\nabla\rho' & = 0 \\`\
` \frac{\partial \mathbf{v}}{\partial t} + (\mathbf{u}\cdot\nabla)\mathbf{v} + \frac{1}{\rho_0}\nabla p' & = 0`\
` \end{align}`
If we make the previous assumptions of the fluid being ideal and the velocity being irrotational, then we have
:
` \begin{align}`\
` p' & = \left(\frac{\partial p}{\partial \rho_{0}}\right)_{s}\rho' = c^{2}\rho' \\`\
` \mathbf{v} & = -\nabla\phi`\
` \end{align}`
Under these assumptions, our linearized sound equations become
:
` \begin{align}`\
` \frac{1}{c^2}\frac{\partial p'}{\partial t} -\rho_0\nabla^2\phi+\frac{1}{c^2}\mathbf{u}\cdot\nabla p' & = 0 \\`\
` -\frac{\partial}{\partial t}(\nabla\phi) - (\mathbf{u}\cdot\nabla)[\nabla\phi] + \frac{1}{\rho_0}\nabla p' & = 0`\
` \end{align}`
Importantly, since $\mathbf{u}$ is a constant, we have $(\mathbf{u}\cdot\nabla)[\nabla\phi] = \nabla[(\mathbf{u}\cdot\nabla)\phi]$, and then the second equation tells us that
:
` \frac{1}{\rho_0} \nabla p' = \nabla\left[\frac{\partial\phi}{\partial t} + (\mathbf{u}\cdot\nabla)\phi\right]`
Or just that
:
` p' = \rho_{0}\left[\frac{\partial\phi}{\partial t} + (\mathbf{u}\cdot\nabla)\phi\right]`
Now, when we use this relation with the fact that $\frac{1}{c^2}\frac{\partial p'}{\partial t} -\rho_0\nabla^2\phi+\frac{1}{c^2}\mathbf{u}\cdot\nabla p' = 0$, alongside cancelling and rearranging terms, we arrive at
:
` \frac{1}{c^2}\frac{\partial^2 \phi}{\partial t^2} - \nabla^2\phi + \frac{1}{c^2}\frac{\partial}{\partial t}[(\mathbf{u}\cdot\nabla)\phi] + \frac{1}{c^2}\frac{\partial}{\partial t}(\mathbf{u}\cdot\nabla\phi) + \frac{1}{c^2}\mathbf{u}\cdot\nabla[(\mathbf{u}\cdot\nabla)\phi] = 0`
We can write this in a familiar form as
$$\left[\frac{1}{c^2}\left(\frac{\partial}{\partial t} + \mathbf{u}\cdot\nabla\right)^{2} - \nabla^{2}\right]\phi = 0$$
This differential equation must be solved with the appropriate boundary conditions. Note that setting $\mathbf{u}=0$ returns us the wave equation. Regardless, upon solving this equation for a moving medium, we then have
$$\begin{align}
\mathbf{v} & = -\nabla \phi \\
p' & = \rho_{0}\left(\frac{\partial}{\partial t} + \mathbf{u}\cdot\nabla\right)\phi\\
\rho' & = \frac{\rho_{0}}{c^{2}}\left(\frac{\partial}{\partial t} + \mathbf{u}\cdot\nabla\right)\phi
\end{align}$$
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American (word)
|
The meaning of the word ***American*** in the English language varies according to the historical, geographical, and political context in which it is used. *American* is derived from *America*, a term originally denoting all of the Americas (also called the Western Hemisphere), ultimately derived from the name of the Florentine explorer and cartographer Amerigo Vespucci (1451--1512). In some expressions, it retains this Pan-American sense, but its usage has evolved over time and, for various historical reasons, the word came to denote people or things specifically from the United States of America. In contemporary English, *American* generally refers to persons or things related to the United States of America; among native English speakers this usage is almost universal, with any other use of the term requiring specification. However, some have argued that \"American\" should be widened to also include people or things from anywhere in the American continents.
The word can be used as either an adjective or a noun (viz. a demonym). In adjectival use, it means \"of or relating to the United States\"; for example, \"Elvis Presley was an American singer\" or \"the man prefers American English\". In its noun form, the word generally means a resident or citizen of the U.S., but is also used for someone whose ethnic identity is simply \"American\". The noun is rarely used in English to refer to people not connected to the United States when intending a geographical meaning.`{{Not verified in body|date=July 2023}}`{=mediawiki} When used with a grammatical qualifier, the adjective *American* can mean \"of or relating to the Americas\", as in Latin American or Indigenous American. Less frequently, the adjective can take this meaning without a qualifier, as in \"American Spanish dialects and pronunciation differ by country\" or the names of the Organization of American States and the American Registry for Internet Numbers (ARIN). A third use of the term pertains specifically to the indigenous peoples of the Americas, for instance, \"In the 16th century, many Americans died from imported diseases during the European conquest\", though this usage is rare, as \"indigenous\", \"First Nations\" or \"Amerindian\" are considered less confusing and generally more appropriate.
Compound constructions which indicate a minority ethnic group, such as \"African Americans\" likewise refer exclusively to people in or from the United States of America, as does the prefix \"Americo-\". For instance, the Americo-Liberians and their language Merico derive their name from the fact that they are descended from African-American settlers, i.e. Blacks who were formerly enslaved in the United States of America.
## Other languages {#other_languages}
French, German, Italian, Japanese, Hebrew, Arabic, and Russian speakers may use cognates of *American* to refer to inhabitants of the Americas or to U.S. nationals. They generally have other terms specific to U.S. nationals, such as the German *US-Amerikaner*, French *étatsunien*, Japanese `{{nihongo||米国人|beikokujin}}`{=mediawiki}, and Italian *statunitense*. These specific terms may be less common than the term *American*.
In French, *états-unien*, *étas-unien* or *étasunien*, from *États-Unis d\'Amérique* (\"United States of America\"), is a rarely used word that distinguishes U.S. things and persons from the adjective *américain*, which denotes persons and things from the United States, but may also refer to \"the Americas\".
Likewise, German\'s use of *U.S.-amerikanisch* and *U.S.-Amerikaner* observe this cultural distinction, solely denoting U.S. things and people. In normal parlance, the adjective \"American\" and its direct cognates are usually used if the context renders the nationality of the person clear. This differentiation is prevalent in German-speaking countries, as indicated by the style manual of the *\[\[Neue Zürcher Zeitung\]\]* (one of the leading German-language newspapers in Switzerland) which dismisses the term *U.S.-amerikanisch* as both \'unnecessary\' and \'artificial\' and recommends replacing it with *amerikanisch*. The respective guidelines of the foreign ministries of Austria, Germany and Switzerland all prescribe *Amerikaner* and *amerikanisch* in reference to the United States for official usage, making no mention of *U.S.-Amerikaner* or *U.S.-amerikanisch*.
Portuguese has *americano*, denoting both a person or thing from the Americas and a U.S. national. For referring specifically to a U.S. national and things, some words used are *estadunidense* (also spelled *estado-unidense*, \"United States person\"), from *Estados Unidos da América*, and *ianque* (\"Yankee\")---both usages exist in Brazil (although \"americano\" is more frequent), but are uncommon in Portugal---but the term most often used, and the only one in Portugal, is *norte-americano*, even though it could, as with its Spanish equivalent, apply to Canadians and Mexicans as well.
In Spanish, *americano* denotes geographic and cultural origin in the New World, as well as (infrequently) a U.S. citizen; the more common term is *estadounidense* (\"United States person\"), which derives from *Estados Unidos de América* (\"United States of America\"). The Spanish term *norteamericano* (\"North American\") is frequently used to refer things and persons from the United States, but this term can also denote people and things from Canada and Mexico. Among Spanish-speakers, North America generally does not include Central America or the Caribbean.
Conversely, in Czech, there is no possibility for disambiguation. *Američan* (m.) and *američanka* (f.) can refer to persons from the United States or from the continents of the Americas, and there is no specific word capable of distinguishing the two meanings. For this reason, the latter meaning is very rarely used, and word *američan(ka)* is used almost exclusively to refer to persons from the United States. The usage is exactly parallel to the English word.
In other languages, however, there is no possibility for confusion. For example, the Chinese word for \"U.S. national\" is `{{Transliteration|zh|měiguórén}}`{=mediawiki} (`{{lang-zh|t=美國人|s=美国人}}`{=mediawiki}) is derived from a word for the United States, `{{Transliteration|zh|měiguó}}`{=mediawiki}, where `{{Transliteration|zh|měi}}`{=mediawiki} is an abbreviation for *Yàměilìjiā* (\"America\") and `{{Transliteration|zh|guó}}`{=mediawiki} is \"country\". The name for the American continents is `{{Transliteration|zh|měizhōu}}`{=mediawiki}, from `{{Transliteration|zh|měi}}`{=mediawiki} plus `{{Transliteration|zh|zhōu}}`{=mediawiki} (\"continent\"). Thus, a `{{Transliteration|zh|měi'''zhōu'''rén}}`{=mediawiki} is an American in the continent sense, and a `{{Transliteration|zh|měi'''guó'''rén}}`{=mediawiki} is an American in the U.S. sense.
Korean and Vietnamese also use unambiguous terms, with Korean having `{{Transliteration|ko|Migug}}`{=mediawiki} (*미국(인)*) for the country versus `{{Transliteration|ko|Amerika}}`{=mediawiki} (*아메리카*) for the continents, and Vietnamese having *Hoa Kỳ* for the country versus *Châu Mỹ* for the continents. Japanese has such terms as well (`{{Transliteration|ja|beikoku(jin)}}`{=mediawiki} \[*米国(人)* versus `{{Transliteration|ja|beishū(jin)}}`{=mediawiki} \[*米洲人*\]), but they are found more in newspaper headlines than in speech, where `{{Transliteration|ja|amerikajin}}`{=mediawiki} predominates.
In Swahili, *Marekani* means specifically the United States, and *Mmarekani* is a U.S. national, whereas the international form *Amerika* refers to the continents, and *Mwamerika* would be an inhabitant thereof. Likewise, the Esperanto word *Ameriko* refers to the continents. For the country there is the term *Usono*. Thus, a citizen of the United States is an *usonano*, whereas an *amerikano* is an inhabitant of the Americas.
## History
The name *America* was coined by Martin Waldseemüller from *Americus Vesputius*, the Latinized version of the name of Amerigo Vespucci (1454--1512), the Florentine explorer who mapped South America\'s east coast and the Caribbean Sea in the early 16th century. Later, Vespucci\'s published letters were the basis of Waldseemüller\'s 1507 map, which is the first usage of *America*. The adjective *American* subsequently denoted the New World.
In the 16th century, European usage of *American* denoted the native inhabitants of the New World. The earliest recorded use of this term in English is in Thomas Hacket\'s 1568 translation of André Thévet\'s book *France Antarctique*; Thévet himself had referred to the natives as *Ameriques*. In the following century, the term was extended to European settlers and their descendants in the Americas. The earliest recorded use of \"English-American\" dates to 1648, in Thomas Gage\'s *The English-American his travail by sea and land: or, a new survey of the West India\'s*.
In English, *American* was used especially for people in British America. Samuel Johnson, the leading English lexicographer, wrote in 1775, before the United States declared independence: \"That the Americans are able to bear taxation is indubitable.\" The Declaration of Independence of July 1776 refers to \"\[the\] unanimous Declaration of the thirteen united States of America\" adopted by the \"Representatives of the united States of America\" on July 4, 1776. The official name of the country was reaffirmed on November 15, 1777, when the Second Continental Congress adopted the Articles of Confederation, the first of which says, \"The Stile of this Confederacy shall be \'The United States of America\'\". The Articles further state: `{{Blockquote|In Witness whereof we have hereunto set our hands in Congress. Done at Philadelphia in the State of Pennsylvania the ninth day of July in the Year of our Lord One Thousand Seven Hundred and Seventy-Eight, and in the Third Year of the independence of America.}}`{=mediawiki}
Thomas Jefferson, newly elected president in May 1801 wrote, \"I am sure the measures I mean to pursue are such as would in their nature be approved by every American who can emerge from preconceived prejudices; as for those who cannot, we must take care of them as of the sick in our hospitals. The medicine of time and fact may cure some of them.\"
In *The Federalist Papers* (1787--88), Alexander Hamilton and James Madison used the adjective *American* with two different meanings: one political and one geographic; \"the American republic\" in Federalist No. 51 and in Federalist No. 70, and, in Federalist No. 24, Hamilton used *American* to denote the lands beyond the U.S.\'s political borders.
Early official U.S. documents show inconsistent usage; the 1778 Treaty of Alliance with France used \"the United States of North America\" in the first sentence, then \"the said united States\" afterwards; \"the United States of America\" and \"the United States of North America\" derive from \"the United Colonies of America\" and \"the United Colonies of North America\". The Treaty of Peace and Amity of September 5, 1795, between the United States and the Barbary States contains the usages \"the United States of North America\", \"citizens of the United States\", and \"American Citizens\".`{{synthesis inline|date=October 2013}}`{=mediawiki}
U.S. President George Washington, in his 1796 *Farewell Address*, declaimed that \"The name of American, which belongs to you in your national capacity, must always exalt the just pride of patriotism more than any appellation.\" Political scientist Virginia L. Arbery notes that, in his *Farewell Address*:
> \"\...Washington invites his fellow citizens to view themselves now as Americans who, out of their love for the truth of liberty, have replaced their maiden names (Virginians, South Carolinians, New Yorkers, etc.) with that of "American". Get rid of, he urges, "any appellation derived from local discriminations." By defining himself as an American rather than as a Virginian, Washington set the national standard for all citizens. \"Over and over, Washington said that America must be something set apart. As he put it to Patrick Henry, \'In a word, I want an *American* character, that the powers of Europe may be convinced we act for *ourselves* and not for *others*.\'\"
As the historian Garry Wills has noted: \"This was a theme dear to Washington. He wrote to Timothy Pickering that the nation \'must never forget that we are Americans; the remembrance of which will convince us we ought not to be French or English\'.\" Washington\'s countrymen subsequently embraced his exhortation with notable enthusiasm.
This semantic divergence among North American anglophones, however, remained largely unknown in the Spanish-American colonies. In 1801, the document titled *Letter to American Spaniards*---published in French (1799), in Spanish (1801), and in English (1808)---might have influenced Venezuela\'s Act of Independence and its 1811 constitution.
The Latter-day Saints\' Articles of Faith refer to the American continents as where they are to build Zion.
Common short forms and abbreviations are the *United States*, the *U.S.*, the *U.S.A.*, and *America*; colloquial versions include the *U.S. of A.* and *the States*. The term *Columbia* (from the Columbus surname) was a popular name for the U.S. and for the entire geographic Americas; its usage is present today in the District of Columbia\'s name. Moreover, the womanly personification of Columbia appears in some official documents, including editions of the U.S. dollar.
## Usage at the United Nations {#usage_at_the_united_nations}
Use of the term *American* for U.S. nationals is common at the United Nations, and financial markets in the United States are referred to as \"American financial markets\".
American Samoa, an unincorporated territory of the United States, is a recognized territorial name at the United Nations.
## Cultural views {#cultural_views}
### Canada
Modern Canadians typically refer to people from the United States as *Americans*, though they seldom refer to the United States as *America*; in English they use the terms *the United States*, *the U.S.*, or (informally) *the States* instead. Because of anti-American sentiment or simply national pride, Canadians never apply the term *American* to themselves. Not being an \"American\" is a part of Canadian identity, with many Canadians resenting being referred to as Americans or mistaken for U.S. citizens. This is often due to others\' inability, particularly overseas, to distinguish English-speaking Canadians from Americans, by their accent or other cultural attributes. Some Canadians have protested the use of *American* as a national demonym. People of American origin in Canada are categorized as \"Other North American origins\" by Statistics Canada for purposes of census counts.
### Spain and Hispanic America {#spain_and_hispanic_america}
The use of *American* as a national demonym for U.S. nationals is challenged, primarily by Hispanic Americans. Spanish speakers in Spain and Hispanic America use the term *estadounidense* to refer to people and things from the United States (from *Estados Unidos*), while *americano* refers to the continents as a whole (from *América*). The term *gringo* is also accepted in many parts of Hispanic America to refer to a person or something from the United States; however, this term may be ambiguous in certain parts. Up to and including the 1992 edition, the *Diccionario de la lengua española*, published by the Real Academia Española, did not include the United States definition in the entry for *americano*; this was added in the 2001 edition. The Real Academia Española advised against using *americanos* exclusively for U.S. nationals:
### Portugal and Brazil {#portugal_and_brazil}
Generally, *americano* denotes \"U.S. citizen\" in Portugal. The adjective currently used by the Portuguese press is *norte-americano*.
In Brazil, the term *americano* is used to address both that which pertains to the Americas and that which pertains to the U.S.; the particular meaning is deduced from context. Alternatively, the term *norte-americano* (\"North American\") is also used in more informal contexts, while *estadunidense* (of the U.S.) is the preferred form in academia. Use of the three terms is common in schools, government, and media. The term *América* is used exclusively for the whole continent, and the U.S. is called *Estados Unidos* (\"United States\") or *Estados Unidos da América* (\"United States of America\"), often abbreviated *EUA*.
## In other contexts {#in_other_contexts}
\"American\" in the 1994 *Associated Press Stylebook* was defined as, \"An acceptable description for a resident of the United States. It also may be applied to any resident or citizen of nations in North or South America.\" Elsewhere, the *AP Stylebook* indicates that \"United States\" must \"be spelled out when used as a noun. Use U.S. (no space) only as an adjective.\"
The entry for \"America\" in *The New York Times Manual of Style and Usage* from 1999 reads: `{{blockquote|[the] terms "America", "American(s)" and "Americas" refer not only to the United States, but to all of North America and South America. They may be used in any of their senses, including references to just the United States, if the context is clear. The countries of the Western Hemisphere are collectively 'the Americas'.}}`{=mediawiki}
Media releases from the Pope and Holy See frequently use \"America\" to refer to the United States, and \"American\" to denote something or someone from the United States.
### International law {#international_law}
At least one international law uses *U.S. citizen* in defining a citizen of the United States rather than *American citizen*; for example, the English version of the North American Free Trade Agreement includes: `{{blockquote|Only air carriers that are "citizens of the United States" may operate aircraft in domestic air service (cabotage) and may provide international scheduled and non-scheduled air service as U.S. air carriers...
Under the Federal Aviation Act of 1958, a "citizen of the United States" means:
:(a) an individual who is a U.S. citizen;
:(b) a partnership in which each member is a U.S. citizen; or
:(c) a U.S. corporation of which the president and at least two-thirds of the board of directors and other managing officers are U.S. citizens, and at least 75 percent of the voting interest in the corporation is owned or controlled by U.S. citizens.<ref>{{cite web | url = http://www.sice.oas.org/trade/nafta/anx1usa.asp | work = North American Free Trade Agreement | title = Annex I: Reservations for Existing Measures and Liberalization Commitments (Chapters 11, 12, and 14) | date = October 7, 1992 | access-date = October 27, 2013 | archive-date = October 29, 2013 | archive-url = https://web.archive.org/web/20131029190838/http://www.sice.oas.org/trade/nafta/anx1usa.asp | url-status = live }}</ref>}}`{=mediawiki}
Many international treaties use the terms *American* and *American citizen*:
- 1796 -- The treaty between the United States and the Dey of the Regency of Algiers on March 7, 1796, protected \"American citizens\".
- 1806 -- The Louisiana Purchase Treaty between France and United States referred to \"American citizens\".
- 1825 -- The treaty between the United States and the Cheyenne tribe refers to \"American citizens\".
- 1848 -- The Treaty of Guadalupe Hidalgo between Mexico and the U.S. uses \"American Government\" to refer to the United States, and \"American tribunals\" to refer to U.S. courts.
- 1858 -- The Treaty of Amity and Commerce between the United States and Japan protected \"American citizens\" and also used \"American\" in other contexts.
- 1898 -- The Treaty of Paris ending the Spanish--American War, known in Spanish as the *Guerra Hispano--Estadounidense* (\"Spain--United States War\") uses \"American\" in reference to United States troops.
- 1966 -- The United States--Thailand Treaty of Amity protects \"Americans\" and \"American corporations\".
### U.S. commercial regulation {#u.s._commercial_regulation}
Products that are labeled, advertised, and marketed in the U.S. as \"Made in the USA\" must be, as set by the Federal Trade Commission (FTC), \"all or virtually all made in the U.S.\" The FTC, to prevent deception of customers and unfair competition, considers an unqualified claim of \"American Made\" to expressly claim exclusive manufacture in the U.S: \"The FTC Act gives the Commission the power to bring law enforcement actions against false or misleading claims that a product is of U.S. origin.\"
## Alternatives
There are a number of alternatives to the demonym *American* as a citizen of the United States that do not simultaneously mean any inhabitant of the Americas. One uncommon alternative is *Usonian*, which usually describes a certain style of residential architecture designed by Frank Lloyd Wright. Other alternatives have also surfaced, but most have fallen into disuse and obscurity. *Merriam-Webster\'s Dictionary of English Usage* says: `{{blockquote|The list contains (in approximate historical order from 1789 to 1939) such terms as Columbian, Columbard, Fredonian, Frede, Unisian, United Statesian, Colonican, Appalacian, Usian, Washingtonian, Usonian, Uessian, U-S-ian, Uesican, United Stater.<ref>{{cite book|title=Merriam-Webster's Dictionary of English Usage|url=https://archive.org/details/merriamwebstersd00merr|url-access=registration|page=[https://archive.org/details/merriamwebstersd00merr/page/88 88]|publisher=Merriam-Webster|year=1994|isbn=9780877791324}}</ref>}}`{=mediawiki} Nevertheless, no alternative to *American* is common.
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Antoninus Pius
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\[[coins denarius Antoninus Pius Marcus Aurelius.jpg\|upright=1.35\|thumb\|Denarius, struck 140 AD with portrait of Antoninus Pius (obverse) and his adoptive son Marcus Aurelius (reverse). Inscription: ANTONINVS AVG PIVS P. P., TR. P., CO\[N](File:Roman)S. III / AVRELIVS CAES. AVG. PII F. CO\[N\]S.\]\] `{{Nerva–Antonine dynasty}}`{=mediawiki}
**Titus Aelius Hadrianus Antoninus Pius** (`{{IPAc-en|ˌ|æ|n|t|ə|ˈ|n|aɪ|n|ə|s|_|ˈ|p|aɪ|ə|s}}`{=mediawiki}; `{{IPA|la|antoˈniːnus ˈpiːjus|lang}}`{=mediawiki}; 19 September 86 -- 7 March 161) was Roman emperor from AD 138 to 161. He was the fourth of the Five Good Emperors from the Nerva--Antonine dynasty.
Born into a senatorial family, Antoninus held various offices during the reign of Emperor Hadrian. He married Hadrian\'s niece Faustina, and Hadrian adopted him as his son and successor shortly before his death. Antoninus acquired the cognomen Pius after his accession to the throne, either because he compelled the Senate to deify his adoptive father, or because he had saved senators sentenced to death by Hadrian in his later years. His reign is notable for the peaceful state of the Empire, with no major revolts or military incursions during this time. A successful military campaign in southern Scotland early in his reign resulted in the construction of the Antonine Wall.
Antoninus was an effective administrator, leaving his successors a large surplus in the treasury, expanding free access to drinking water throughout the Empire, encouraging legal conformity, and facilitating the enfranchisement of freed slaves. He died of illness in AD 161 and was succeeded by his adopted sons Marcus Aurelius and Lucius Verus as co-emperors.
## Early life {#early_life}
### Childhood and family {#childhood_and_family}
Antoninus Pius was born Titus Aurelius Fulvus Boionius Antoninus in 86, near Lanuvium (modern-day Lanuvio) in Italy to Titus Aurelius Fulvus, consul in 89, and wife Arria Fadilla. The Aurelii Fulvi were an Aurelian family settled in Nemausus (modern Nîmes). Titus Aurelius Fulvus was the son of a senator of the same name, who, as legate of Legio III Gallica, had supported Vespasian in his bid to the Imperial office and been rewarded with a suffect consulship, plus an ordinary one under Domitian in 85. The Aurelii Fulvi were therefore a relatively new senatorial family from Gallia Narbonensis whose rise to prominence was supported by the Flavians. The link between Antoninus\'s family and their home province explains the increasing importance of the post of proconsul of Gallia Narbonensis during the late second century.
Antoninus\'s father had no other children and died shortly after his 89 ordinary consulship. Antoninus was raised by his maternal grandfather Gnaeus Arrius Antoninus, reputed by contemporaries to be a man of integrity and culture and a friend of Pliny the Younger. The Arrii Antonini were an older senatorial family from Italy, very influential during Nerva\'s reign. Arria Fadilla, Antoninus\'s mother, married afterwards Publius Julius Lupus, suffect consul in 98; from that marriage came two daughters, Arria Lupula and Julia Fadilla.
### Marriage and children {#marriage_and_children}
Some time between 110 and 115, Antoninus married Annia Galeria Faustina the Elder. They are believed to have enjoyed a happy marriage. Faustina was the daughter of consul Marcus Annius Verus (II) and Rupilia Faustina (often thought to be a step-sister to the Empress Vibia Sabina or more likely a granddaughter of the emperor Vitellius.) Faustina was a beautiful woman, and despite rumours about her character, it is clear that Antoninus cared for her deeply.
Faustina bore Antoninus four children, two sons and two daughters. They were:
- Marcus Aurelius Fulvus Antoninus (died before 138); his sepulchral inscription has been found at the Mausoleum of Hadrian in Rome.
- Marcus Galerius Aurelius Antoninus (died before 138); his sepulchral inscription has been found at the Mausoleum of Hadrian in Rome. His name appears on a Greek Imperial coin.
- Aurelia Fadilla (died in 135); she married Lucius Plautius Lamia Silvanus, consul 145. She appeared to have no children with her husband; and her sepulchral inscription has been found in Italy.
- Annia Galeria Faustina Minor or Faustina the Younger (between 125 and 130--175), a future Roman Empress, married her maternal cousin Marcus Aurelius in 146.
When Faustina died in 141, Antoninus was greatly distressed. In honour of her memory, he asked the Senate to deify her as a goddess, and authorised the construction of a temple to be built in the Roman Forum in her name, with priestesses serving in her temple. He had various coins with her portrait struck in her honor. These coins were scripted \"DIVA FAUSTINA\" and were elaborately decorated. He further founded a charity, calling it *Puellae Faustinianae* or *Girls of Faustina*, which assisted destitute girls of good family. Finally, Antoninus created a new *alimenta*, a Roman welfare programme, as part of *Cura Annonae*.
The emperor never remarried. Instead, he lived with Galeria Lysistrate, Faustina\'s freedwoman. Concubinage was a form of female companionship sometimes chosen by powerful men in Ancient Rome, especially widowers like Vespasian, and Marcus Aurelius. Their union could not produce any legitimate offspring who could threaten any heirs, such as those of Antoninus. Also, as one could not have a wife and an official concubine (or two concubines) at the same time, Antoninus avoided being pressed into a marriage with a noblewoman from another family. (Later, Marcus Aurelius would also reject the advances of his former fiancée Ceionia Fabia, Lucius Verus\'s sister, on the grounds of protecting his children from a stepmother, and took a concubine instead.)
### Favour with Hadrian {#favour_with_hadrian}
Having filled the offices of quaestor and praetor with more than usual success, he obtained the consulship in 120 having as his colleague Lucius Catilius Severus. He was next appointed by the Emperor Hadrian as one of the four proconsuls to administer Italia, his district including Etruria, where he had estates. He then greatly increased his reputation by his conduct as proconsul of Asia, probably during 134--135.
He acquired much favor with Hadrian, who adopted him as his son and successor on 25 February 138, after the death of his first adopted son Lucius Aelius, on the condition that Antoninus would in turn adopt Marcus Annius Verus, the son of his wife\'s brother, and Lucius, son of Lucius Aelius, who afterwards became the emperors Marcus Aurelius and Lucius Verus. He also adopted (briefly) the name Imperator Titus Aelius Caesar Antoninus, in preparation for his rule. There seems to have been some opposition to Antoninus\'s appointment on the part of other potential claimants, among them his former consular colleague Lucius Catilius Severus, then prefect of the city. Nevertheless, Antoninus assumed power without opposition.
## Emperor
On his accession, Antoninus\'s name and style became *Imperator Caesar Titus Aelius Hadrianus Antoninus Augustus*. One of his first acts as emperor was to persuade the Senate to grant divine honours to Hadrian, which they had at first refused; his efforts to persuade the Senate to grant these honours is the most likely reason given for his title of *Pius* (dutiful in affection; compare *pietas*). Two other reasons for this title are that he would support his aged father-in-law with his hand at Senate meetings and that he had saved those men that Hadrian, during his period of ill health, had condemned to death.
Immediately after Hadrian\'s death, Antoninus approached Marcus and requested that his marriage arrangements be amended: Marcus\'s betrothal to Ceionia Fabia would be annulled, and he would be betrothed to Faustina, Antoninus\'s daughter instead. Faustina\'s betrothal to Ceionia\'s brother Lucius Commodus, Marcus\'s future co-emperor, would also have to be annulled. Marcus consented to Antoninus\'s proposal.
Antoninus built temples, theaters, and mausoleums, promoted the arts and sciences, and bestowed honours and financial rewards upon the teachers of rhetoric and philosophy. Antoninus made few initial changes when he became emperor, leaving the arrangements instituted by Hadrian as undisturbed as possible. Epigraphical and prosopographical research has revealed that Antoninus\'s imperial ruling team centered around a group of closely knit senatorial families, most of them members of the priestly congregation for the cult of Hadrian, the *sodales Hadrianales*. According to the German historian H.-G. Pflaum, prosopographical research of Antoninus\'s ruling team allows us to grasp the deeply conservative character of the ruling senatorial caste.
He owned palatial villas near Lanuvium and Villa Magna (Latium) and his ancestral estate at Lorium (Etruria).
### Lack of warfare {#lack_of_warfare}
There are no records of his involvement in military acts during his tenure, with J. J. Wilkes noting that he likely never saw or commanded a Roman army and was never within five hundred miles of a legion throughout his twenty-three-year reign.
His reign was the most peaceful in the entire history of the Principate, even though there were several military disturbances in the Empire in his time. Such disturbances happened in Mauretania, where a senator was named as governor of Mauretania Tingitana in place of the usual equestrian procurator and cavalry reinforcements from Pannonia were brought in, towns such as Sala and Tipasa being fortified. Similar disturbances took place in Judea, and amongst the Brigantes in Britannia; however, these were considered less serious than prior (and later) revolts among both. It was however in Britain that Antoninus decided to follow a new, more aggressive path, with the appointment of a new governor in 139, Quintus Lollius Urbicus, a native of Numidia and previously governor of Germania Inferior as well as a new man.
Under instructions from the emperor, Lollius undertook an invasion of southern Scotland, winning some significant victories and constructing the Antonine Wall from the Firth of Forth to the Firth of Clyde. However, the wall was soon gradually decommissioned during the mid-150s and eventually abandoned late during the reign (early 160s) for reasons that are still unclear. Antonine\'s Wall is mentioned in just one literary source, Antoninus\'s biography in the *Historia Augusta*. Pausanias makes a brief and confused mention of a war in Britain. In one inscription honouring Antoninus, erected by Legio II Augusta, which participated in the building of the Wall, a relief showing four naked prisoners, one of them beheaded, seems to stand for some actual warfare.
Although Antonine\'s Wall was, in principle, much shorter (37 miles in length as opposed to 73) and, at first sight, more defensible than Hadrian\'s Wall, the additional area that it enclosed within the Empire was barren, with land use for grazing already in decay. This meant that supply lines to the wall were strained enough such that the costs of maintaining the additional territory outweighed the benefits of doing so. Also, in the absence of urban development and the ensuing Romanization process, the rear of the wall could not be lastingly pacified.
It has been speculated that the invasion of Lowland Scotland and the building of the wall had to do mostly with internal politics, that is, offering Antoninus an opportunity to gain some modicum of necessary military prestige at the start of his reign. An Imperial salutation followed the campaign in Britannia---that is, Antoninus formally took for the second (and last) time the title of Imperator in 142. The fact that around the same time coins were struck announcing a victory in Britain points to Antoninus\'s need to publicise his achievements. The orator Fronto was later to say that, although Antoninus bestowed the direction of the British campaign to others, he should be regarded as the helmsman who directed the voyage, whose glory, therefore, belonged to him.
That this quest for some military achievement responded to an actual need is proved by the fact that, although generally peaceful, Antoninus\'s reign was not free from attempts at usurpation: *Historia Augusta* mentions two, made by the senators Cornelius Priscianus (\"for disturbing the peace of Spain\"; Priscianus had also been Lollius Urbicus\'s successor as governor of Britain) and Atilius Rufius Titianus (possibly a troublemaker already exiled under Hadrian). Both attempts are confirmed by the Fasti Ostienses and by the erasing of Priscianus\' name from an inscription. In both cases, Antoninus was not in formal charge of the ensuing repression: Priscianus committed suicide and Titianus was found guilty by the Senate, with Antoninus abstaining from sequestering their families\' properties.
There were also some troubles in Dacia Inferior, which required the granting of additional powers to the procurator governor and the dispatch of additional soldiers to the province. On the northern Black Sea coast, the Greek city of Olbia was held against the Scythians. Also during his reign the governor of Upper Germany, probably Gaius Popillius Carus Pedo, built new fortifications in the Agri Decumates, advancing the Limes Germanicus fifteen miles forward in his province and neighboring Raetia. In the East, Roman suzerainty over Armenia was retained by the choice in AD 140 of Arsacid scion Sohaemus as client king.
Nevertheless, Antoninus was virtually unique among emperors in that he dealt with these crises without leaving Italy once during his reign, but instead dealt with provincial matters of war and peace through their governors or through imperial letters to the cities such as Ephesus (of which some were publicly displayed). His contemporaries and later generations highly praised this style of government.
Antoninus was the last Roman Emperor recognised by the Indian Kingdoms, especially the Kushan Empire. Raoul McLaughlin quotes Aurelius Victor as saying, \"The Indians, the Bactrians, and the Hyrcanians all sent ambassadors to Antoninus. They had all heard about the spirit of justice held by this great emperor, justice that was heightened by his handsome and grave countenance, and his slim and vigorous figure.\" Due to the outbreak of the Antonine epidemic and wars against northern Germanic tribes, the reign of Marcus Aurelius was forced to alter the focus of foreign policies, and matters relating to the Far East were increasingly abandoned in favour of those directly concerning the Empire\'s survival.
### Economy and administration {#economy_and_administration}
Antoninus was regarded as a skilled administrator and builder. Despite an extensive building directive---the free access of the people of Rome to drinking water was expanded with the construction of aqueducts, not only in Rome but throughout the Empire, as well as bridges and roads---the emperor still managed to leave behind a sizable public treasury of around 2.7 billion sesterces. Rome would not witness another Emperor leaving his successor with a surplus for a long time, but the treasury was depleted almost immediately after Antoninus\'s reign due to the Antonine Plague brought back by soldiers after the Parthian victory.
The Emperor also famously suspended the collection of taxes from multiple cities affected by natural disasters, such as when fires struck Rome and Narbona, and earthquakes affected Rhodes and the Province of Asia. He offered hefty financial grants for rebuilding and recovery of various Greek cities after two serious earthquakes: the first, c. 140, which mainly affected Rhodes and other islands; the second, in 152, which hit Cyzicus (where the huge and newly built Temple to Hadrian was destroyed), Ephesus, and Smyrna. Antoninus\'s financial help earned him praise from Greek writers such as Aelius Aristides and Pausanias. These cities received the usual honorific accolades from Antoninus, such as when he commanded that all governors of Asia should enter the province when taking office through Ephesus. Ephesus was especially favoured by Antoninus, who confirmed and upheld its distinction of having two temples for the imperial cult (neocorate), therefore having first place in the list of imperial honor titles, surpassing both Smyrna and Pergamon.
In his dealings with Greek-speaking cities, Antoninus followed the policy adopted by Hadrian of ingratiating himself with local elites, especially with local intellectuals: philosophers, teachers of literature, rhetoricians, and physicians were explicitly exempted from any duties involving private spending for civic purposes, a privilege granted by Hadrian that Antoninus confirmed by means of an edict preserved in the Digest (27.1.6.8). Antoninus also created a chair for the teaching of rhetoric in Athens.
Antoninus was known as an avid observer of rites of religion and formal celebrations, both Roman and foreign. He is known for having increasingly formalized the official cult offered to the Great Mother, which from his reign onwards included a bull sacrifice, a taurobolium, formerly only a private ritual, now being also performed for the sake of the Emperor\'s welfare. Antoninus also offered patronage to the worship of Mithras, to whom he erected a temple in Ostia. In 148, he presided over the celebrations of the 900th anniversary of the founding of Rome.
### Legal reforms {#legal_reforms}
Antoninus tried to portray himself as a magistrate of the *res publica*, no matter how extended and ill-defined his competencies were. He is credited with splitting the imperial treasury, the fiscus. This splitting had to do with the division of imperial properties into two parts. Firstly, the fiscus itself, or *patrimonium*, meaning the properties of the \"Crown\", the hereditary properties of each succeeding person that sat on the throne, transmitted to his successors in office, regardless of their previous membership in the imperial family. Secondly, the *res privata*, the \"private\" properties tied to the personal maintenance of the emperor and his family, something like a Privy Purse. An anecdote in the *Historia Augusta* biography, where Antoninus replies to Faustina (who complained about his stinginess) that \"we have gained an empire \[and\] lost even what we had before,\" possibly relates to Antoninus\'s actual concerns at the creation of the *res privata*. While still a private citizen, Antoninus had increased his personal fortune significantly using various legacies, the consequence of his caring scrupulously for his relatives. Also, Antoninus left behind him a reputation for stinginess and was probably determined not to leave his personal property to be \"swallowed up by the demands of the imperial throne\".
The *res privata* lands could be sold and/or given away, while the *patrimonium* properties were regarded as public. It was a way of pretending that the Imperial function---and most properties attached to it---was a public one, formally subject to the authority of the Senate and the Roman people. That the distinction played no part in subsequent political history---that the *personal* power of the princeps absorbed his role as office-holder---proves that the autocratic logic of the imperial order had already subsumed the old republican institutions.
Of the public transactions of this period, there is only the scantiest of information. However, to judge by what is extant, those twenty-two years were not remarkably eventful compared to those before and after the reign. However, Antoninus did take a great interest in the revision and practice of the law throughout the empire. One of his chief concerns was to having local communities conform their legal procedures to existing Roman norms: in a case concerning the repression of banditry by local police officers (\"irenarchs\", Greek for \"peacekeepers\") in Asia Minor, Antoninus ordered that these officers should not treat suspects as already condemned, and also keep a detailed copy of their interrogations, to be used in the possibility of an appeal to the Roman governor. Also, although Antoninus was not an innovator, he would not always follow the absolute letter of the law. Rather, he was driven by concerns over humanity and equality and introduced into Roman law many important new principles based upon this notion.
In this, the emperor was assisted by five chief lawyers: Lucius Fulvius Aburnius Valens, an author of legal treatises; Lucius Ulpius Marcellus, a prolific writer; and three others. Of these three, the most prominent was Lucius Volusius Maecianus, a former military officer turned by Antoninus into a civil procurator, and who, given his subsequent career (discovered on the basis of epigraphical and prosopographic research), was the emperor\'s most important legal adviser. Maecianus would eventually be chosen to occupy various prefectures (see below) as well as to conduct the legal studies of Marcus Aurelius. He also authored an extensive work on *Fidei commissa* (Testamentary Trusts). As a hallmark of the increased connection between jurists and the imperial government, Antoninus\'s reign also saw the appearance of the *Institutes* of Gaius, an elementary legal textbook for beginners. Antoninus passed measures to facilitate the enfranchisement of slaves. Mostly, he favoured the principle of *favor libertatis*, giving the putative freedman the benefit of the doubt when the claim to freedom was not clear-cut. Also, he punished the killing of a slave by their master without previous trial and determined that slaves could be forcibly sold to another master by a proconsul in cases of consistent mistreatment. Antoninus upheld the enforcement of contracts for selling of female slaves forbidding their further employment in prostitution. In criminal law, Antoninus introduced the important principle of the presumption of innocence---namely, that accused persons are not to be treated as guilty before trial, as in the case of the irenarchs (see above). Antoninus also asserted the principle that the trial was to be held and the punishment inflicted in the place where the crime had been committed. He mitigated the use of torture in examining slaves by certain limitations. Thus, he prohibited the application of torture to children under fourteen years, though this rule had exceptions. However, it must be stressed that Antoninus *extended*, using a rescript, the use of torture as a means of obtaining evidence to pecuniary cases, when it had been applied up until then only in criminal cases. Also, already at the time torture of free men of low status (*humiliores*) had become legal, as proved by the fact that Antoninus exempted town councillors expressly from it, and also free men of high rank (*honestiores*) in general.
One highlight during his reign occurred in 148, with the 900th anniversary of the foundation of Rome being celebrated by hosting magnificent games in the city. It lasted many days, and a host of exotic animals were killed, including elephants, giraffes, tigers, rhinoceroses, crocodiles and hippopotamuses. While this increased Antoninus\'s popularity, the frugal emperor had to debase the Roman currency. He decreased the silver purity of the denarius from 89% to 83.5, the actual silver weight dropping from 2.88 grams to 2.68 grams.
Antoninus is a likely candidate for the Antoninus named multiple times in the Talmud as a friend of Rabbi Judah Ha-Nasi. In the Talmudic tractate *Avodah Zarah* 10a--b, Rabbi Judah---exceptionally wealthy and highly revered in Rome---shared a close friendship with a man named Antoninus (possibly Antoninus Pius), who frequently sought his counsel on spiritual (in this context, Jewish), philosophical, and governance matters.
### Diplomatic mission to China {#diplomatic_mission_to_china}
The first group of people claiming to be an ambassadorial mission of Romans to China was recorded in 166 AD by the *Hou Hanshu*. Harper (2017) states that the embassy was likely to be a group of merchants, as many Roman merchants traveled to India and some might have gone beyond, while there are no records of official ambassadors of Rome travelling as far east. The group came to Emperor Huan of Han China and claimed to be an embassy from \"Andun\" (`{{Lang-zh|安敦 ''āndūn''}}`{=mediawiki}; for *Anton*-inus), \"king of Daqin\" (Rome). As Antoninus Pius died in 161, leaving the empire to his adoptive son Marcus Aurelius (Antoninus), and the envoy arrived in 166, confusion remains about who sent the mission, given that both emperors were named \"Antoninus\". The Roman mission came from the south (therefore probably by sea), entering China by the frontier province of Jiaozhi at Rinan or Tonkin (present-day northern Vietnam). It brought presents of rhinoceros horns, ivory, and tortoise shell, probably acquired in South Asia. The text states explicitly that it was the first time there had been direct contact between the two countries.
Furthermore, a piece of Republican-era Roman glassware has been found at a Western Han tomb in Guangzhou along the South China Sea, dated to the early 1st century BC. Roman golden medallions made during the reign of Antoninus Pius and perhaps even Marcus Aurelius have been found at Óc Eo in southern Vietnam, then part of the Kingdom of Funan near the Chinese province of Jiaozhi. This may have been the port city of Kattigara, described by Ptolemy (c. 150) as being visited by a Greek sailor named Alexander and lying beyond the Golden Chersonese (i.e., Malay Peninsula). Roman coins from the reigns of Tiberius to Aurelian have been discovered in Xi\'an, China (site of the Han capital Chang\'an), although the significantly greater amount of Roman coins unearthed in India suggest the Roman maritime trade for purchasing Chinese silk was centered there, not in China or even the overland Silk Road running through ancient Iran.
## Death and legacy {#death_and_legacy}
In 156, Antoninus Pius turned 70. He found it difficult to keep himself upright without stays. He started nibbling on dry bread to give him the strength to stay awake through his morning receptions.
Marcus Aurelius had already been created consul with Antoninus in 140, receiving the title of Caesar, i.e., heir apparent. As Antoninus aged, Marcus took on more administrative duties. Marcus\'s administrative duties increased again after the death, in 156 or 157, of one of Antoninus\'s most trusted advisers, Marcus Gavius Maximus.
For twenty years, Gavius Maximus had been praetorian prefect, an office that was as much secretarial as military. Gavius Maximus had been awarded with the consular insignia and the honours due a senator. He had a reputation as a most strict disciplinarian (*vir severissimus*, according to *Historia Augusta*) and some fellow equestrian procurators held lasting grudges against him. A procurator named Gaius Censorius Niger died while Gavius Maximus was alive. In his will, Censorius Niger vilified Maximus, creating serious embarrassment for one of the heirs, the orator Fronto.
Gavius Maximus\'s death initiated a change in the ruling team. It has been speculated that it was the legal adviser Lucius Volusius Maecianus who assumed the role of grey eminence. Maecianus was briefly Praefect of Egypt, and subsequently Praefectus annonae in Rome. If it was Maecianus who rose to prominence, he may have risen precisely in order to prepare the incoming---and unprecedented---joint succession. In 160, Marcus and Lucius were designated joint consuls for the following year. Perhaps Antoninus was already ill; in any case, he died before the year was out, probably on 7 March.
Two days before his death, the biographer reports, Antoninus was at his ancestral estate at Lorium, in Etruria, about 12 mi from Rome. He ate Alpine cheese at dinner quite greedily. In the night he vomited; he had a fever the next day. The day after that, he summoned the imperial council, and passed the state and his daughter to Marcus. The emperor gave the keynote to his life in the last word that he uttered: when the tribune of the night-watch came to ask the password, he responded, \"aequanimitas\" (equanimity). He then turned over, as if going to sleep, and died. His death closed out the longest reign since Augustus (surpassing Tiberius by a couple of months). His record for the second-longest reign would be unbeaten for 168 years, until 329 when it was surpassed by Constantine the Great.
Antoninus Pius\' funeral ceremonies were, in the words of the biographer, \"elaborate\". If his funeral followed the pattern of past funerals, his body would have been incinerated on a pyre at the Campus Martius, while his spirit would rise to the gods\' home in the heavens. However, it seems that this was not the case: according to his *Historia Augusta* biography (which seems to reproduce an earlier, detailed report) Antoninus\'s body (and not his ashes) was buried in Hadrian\'s mausoleum. After a seven-day interval (*justitium*), Marcus and Lucius nominated their father for deification. In contrast to their behaviour during Antoninus\'s campaign to deify Hadrian, the senate did not oppose the emperors\' wishes. A *flamen*, or cultic priest, was appointed to minister the cult of the deified Antoninus, now *Divus Antoninus*.
A column was dedicated to Antoninus on the Campus Martius, and the temple he had built in the Forum in 141 to his deified wife Faustina was rededicated to the deified Faustina and the deified Antoninus. It survives as the church of San Lorenzo in Miranda.
### Historiography
The only intact account of his life handed down to us is that of the *Augustan History*, an unreliable and mostly fabricated work. Nevertheless, it still contains information that is considered reasonably sound; for instance, it is the only source that mentions the erection of the Antonine Wall in Britain.
Antoninus in many ways was the ideal of the landed gentleman praised not only by ancient Romans, but also by later scholars of classical history, such as Edward Gibbon or the author of the article on Antoninus Pius in the *Encyclopædia Britannica* Eleventh Edition.
Some historians have a less positive view of his reign. According to the historian J. B. Bury,
German historian Ernst Kornemann has had it in his *Römische Geschichte* \[2 vols., ed. by H. Bengtson, Stuttgart 1954\] that the reign of Antoninus comprised \"a succession of grossly wasted opportunities\", given the upheavals that were to come. There is more to this argument, given that the Parthians in the East were themselves soon to make no small amount of mischief after Antoninus\'s death. Kornemann\'s brief is that Antoninus might have waged preventive wars to head off these outsiders. Michael Grant agrees that it is possible that had Antoninus acted decisively sooner (it appears that, on his death bed, he was preparing a large-scale action against the Parthians), the Parthians might have been unable to choose their own time, but current evidence is not conclusive. Grant opines that Antoninus and his officers did act in a resolute manner dealing with frontier disturbances of his time, although conditions for long-lasting peace were not created. On the whole, according to Grant, Marcus Aurelius\'s eulogistic picture of Antoninus seems deserved, and Antoninus appears to have been a conservative and nationalistic (although he respected and followed Hadrian\'s example of Philhellenism moderately) emperor who was not tainted by the blood of either citizen or foe, combined and maintained Numa Pompilius\'s good fortune, pacific dutifulness and religious scrupulousness, and whose laws removed anomalies and softened harshnesses.
Krzysztof Ulanowski argues that the claims of military inability are exaggerated, considering that although the sources praise Antoninus\'s love for peace and his efforts \"rather to defend, than enlarge the provinces\", he could hardly be considered a pacifist, as shown by the conquest of the Lowlands, the building of the Antonine Wall and the expansion of Germania Superior. Ulanowski also praises Antoninus for being successful in deterrence by diplomatic means.
### Descendants
Although only one of his four children survived to adulthood, Antoninus came to be ancestor to four generations of prominent Romans, including the Emperor Commodus. Hans-Georg Pflaum has identified five direct descendants of Antoninus and Faustina who were consuls in the first half of the third century.
1. Marcus Aurelius Fulvus Antoninus (died before 138), died young without issue
2. Marcus Galerius Aurelius Antoninus (died before 138), died young without issue
3. Aurelia Fadilla (died in 135), who married Lucius Plautius Lamia Silvanus, suffect consul in 145; no children known for certain.
4. Annia Galeria Faustina the Younger (21 September between 125 and 130--175), had several children; those who had children were:
1. Annia Aurelia Galeria Lucilla (7 March 150--182?), whose children included:
1. Tiberius Claudius Pompeianus
2. Annia Galeria Aurelia Faustina (151--?), whose children included:
1. Tiberius Claudius Severus Proculus
1. Empress Annia Faustina, Elagabalus\'s third wife
3. Annia Aurelia Fadilla (159 -- after 211)
4. Annia Cornificia Faustina Minor (160--213)
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Anisotropy
|
thumb\|upright=1.36\|WMAP image of the tiny anisotropies in the cosmic microwave background radiation **Anisotropy** (`{{IPAc-en|ˌ|ae|n|aɪ|ˈ|s|ɒ|t|r|ə|p|i|,_|ˌ|æ|n|ɪ|-}}`{=mediawiki}) is the structural property of non-uniformity in different directions, as opposed to isotropy. An anisotropic object or pattern has properties that differ according to direction of measurement. For example, many materials exhibit very different physical or mechanical properties when measured along different axes, e.g. absorbance, refractive index, conductivity, and tensile strength.
An example of anisotropy is light coming through a polarizer. Another is wood, which is easier to split along its grain than across it because of the directional non-uniformity of the grain (the grain is the same in one direction, not all directions).
## Fields of interest {#fields_of_interest}
### Computer graphics {#computer_graphics}
In the field of computer graphics, an anisotropic surface changes in appearance as it rotates about its geometric normal, as is the case with velvet.
Anisotropic filtering (AF) is a method of enhancing the image quality of textures on surfaces that are far away and viewed at a shallow angle. Older techniques, such as bilinear and trilinear filtering, do not take into account the angle a surface is viewed from, which can result in aliasing or blurring of textures. By reducing detail in one direction more than another, these effects can be reduced easily.
### Chemistry
A chemical anisotropic filter, as used to filter particles, is a filter with increasingly smaller interstitial spaces in the direction of filtration so that the proximal regions filter out larger particles and distal regions increasingly remove smaller particles, resulting in greater flow-through and more efficient filtration.
In fluorescence spectroscopy, the fluorescence anisotropy, calculated from the polarization properties of fluorescence from samples excited with plane-polarized light, is used, e.g., to determine the shape of a macromolecule. Anisotropy measurements reveal the average angular displacement of the fluorophore that occurs between absorption and subsequent emission of a photon.
In NMR spectroscopy, the orientation of nuclei with respect to the applied magnetic field determines their chemical shift. In this context, anisotropic systems refer to the electron distribution of molecules with abnormally high electron density, like the pi system of benzene. This abnormal electron density affects the applied magnetic field and causes the observed chemical shift to change.
### Real-world imagery {#real_world_imagery}
Images of a gravity-bound or man-made environment are particularly anisotropic in the orientation domain, with more image structure located at orientations parallel with or orthogonal to the direction of gravity (vertical and horizontal).
### Physics
Physicists from University of California, Berkeley reported about their detection of the cosmic anisotropy in cosmic microwave background radiation in 1977. Their experiment demonstrated the Doppler shift caused by the movement of the earth with respect to the early Universe matter, the source of the radiation. Cosmic anisotropy has also been seen in the alignment of galaxies\' rotation axes and polarization angles of quasars.`{{fact|date=March 2025}}`{=mediawiki}
Physicists use the term anisotropy to describe direction-dependent properties of materials. Magnetic anisotropy, for example, may occur in a plasma, so that its magnetic field is oriented in a preferred direction. Plasmas may also show \"filamentation\" (such as that seen in lightning or a plasma globe) that is directional.`{{fact|date=March 2025}}`{=mediawiki}
An *anisotropic liquid* has the fluidity of a normal liquid, but has an average structural order relative to each other along the molecular axis, unlike water or chloroform, which contain no structural ordering of the molecules. Liquid crystals are examples of anisotropic liquids.`{{fact|date=March 2025}}`{=mediawiki}
Some materials conduct heat in a way that is isotropic, that is independent of spatial orientation around the heat source. Heat conduction is more commonly anisotropic, which implies that detailed geometric modeling of typically diverse materials being thermally managed is required. The materials used to transfer and reject heat from the heat source in electronics are often anisotropic.
Many crystals are anisotropic to light (\"optical anisotropy\"), and exhibit properties such as birefringence. Crystal optics describes light propagation in these media. An \"axis of anisotropy\" is defined as the axis along which isotropy is broken (or an axis of symmetry, such as normal to crystalline layers). Some materials can have multiple such optical axes.`{{fact|date=March 2025}}`{=mediawiki}
### Geophysics and geology {#geophysics_and_geology}
Seismic anisotropy is the variation of seismic wavespeed with direction. Seismic anisotropy is an indicator of long range order in a material, where features smaller than the seismic wavelength (e.g., crystals, cracks, pores, layers, or inclusions) have a dominant alignment. This alignment leads to a directional variation of elasticity wavespeed. Measuring the effects of anisotropy in seismic data can provide important information about processes and mineralogy in the Earth; significant seismic anisotropy has been detected in the Earth\'s crust, mantle, and inner core.
Geological formations with distinct layers of sedimentary material can exhibit electrical anisotropy; electrical conductivity in one direction (e.g. parallel to a layer), is different from that in another (e.g. perpendicular to a layer). This property is used in the gas and oil exploration industry to identify hydrocarbon-bearing sands in sequences of sand and shale. Sand-bearing hydrocarbon assets have high resistivity (low conductivity), whereas shales have lower resistivity. Formation evaluation instruments measure this conductivity or resistivity, and the results are used to help find oil and gas in wells. The mechanical anisotropy measured for some of the sedimentary rocks like coal and shale can change with corresponding changes in their surface properties like sorption when gases are produced from the coal and shale reservoirs.
The hydraulic conductivity of aquifers is often anisotropic for the same reason. When calculating groundwater flow to drains or to wells, the difference between horizontal and vertical permeability must be taken into account; otherwise the results may be subject to error.
Most common rock-forming minerals are anisotropic, including quartz and feldspar. Anisotropy in minerals is most reliably seen in their optical properties. An example of an isotropic mineral is garnet.
Igneous rock like granite also shows the anisotropy due to the orientation of the minerals during the solidification process.
### Medical acoustics {#medical_acoustics}
Anisotropy is also a well-known property in medical ultrasound imaging describing a different resulting echogenicity of soft tissues, such as tendons, when the angle of the transducer is changed. Tendon fibers appear hyperechoic (bright) when the transducer is perpendicular to the tendon, but can appear hypoechoic (darker) when the transducer is angled obliquely. This can be a source of interpretation error for inexperienced practitioners.
### Materials science and engineering {#materials_science_and_engineering}
Anisotropy, in materials science, is a material\'s directional dependence of a physical property. This is a critical consideration for materials selection in engineering applications. A material with physical properties that are symmetric about an axis that is normal to a plane of isotropy is called a transversely isotropic material. Tensor descriptions of material properties can be used to determine the directional dependence of that property. For a monocrystalline material, anisotropy is associated with the crystal symmetry in the sense that more symmetric crystal types have fewer independent coefficients in the tensor description of a given property. When a material is polycrystalline, the directional dependence on properties is often related to the processing techniques it has undergone. A material with randomly oriented grains will be isotropic, whereas materials with texture will be often be anisotropic. Textured materials are often the result of processing techniques like cold rolling, wire drawing, and heat treatment.
Mechanical properties of materials such as Young\'s modulus, ductility, yield strength, and high-temperature creep rate, are often dependent on the direction of measurement. Fourth-rank tensor properties, like the elastic constants, are anisotropic, even for materials with cubic symmetry. The Young\'s modulus relates stress and strain when an isotropic material is elastically deformed; to describe elasticity in an anisotropic material, stiffness (or compliance) tensors are used instead.
In metals, anisotropic elasticity behavior is present in all single crystals with three independent coefficients for cubic crystals, for example. For face-centered cubic materials such as nickel and copper, the stiffness is highest along the \<111\> direction, normal to the close-packed planes, and smallest parallel to \<100\>. Tungsten is so nearly isotropic at room temperature that it can be considered to have only two stiffness coefficients; aluminium is another metal that is nearly isotropic.
For an isotropic material, $G = E/[2(1 + \nu)],$ where $G$ is the shear modulus, $E$ is the Young\'s modulus, and $\nu$ is the material\'s Poisson\'s ratio. Therefore, for cubic materials, we can think of anisotropy, $a_r$, as the ratio between the empirically determined shear modulus for the cubic material and its (isotropic) equivalent: $a_r = \frac{G}{E/[2(1 + \nu)]} = \frac{2(1+\nu)G}{E} \equiv \frac{2 C_{44}}{C_{11} - C_{12}}.$
The latter expression is known as the Zener ratio, $a_r$, where $C_{ij}$ refers to elastic constants in Voigt (vector-matrix) notation. For an isotropic material, the ratio is one.
Limitation of the Zener ratio to cubic materials is waived in the Tensorial anisotropy index A^T^ that takes into consideration all the 27 components of the fully anisotropic stiffness tensor. It is composed of two major parts $A^I$and $A^A$, the former referring to components existing in cubic tensor and the latter in anisotropic tensor so that $A^T = A^I+A^A .$ This first component includes the modified Zener ratio and additionally accounts for directional differences in the material, which exist in orthotropic material, for instance. The second component of this index $A^A$ covers the influence of stiffness coefficients that are nonzero only for non-cubic materials and remains zero otherwise.
Fiber-reinforced or layered composite materials exhibit anisotropic mechanical properties, due to orientation of the reinforcement material. In many fiber-reinforced composites like carbon fiber or glass fiber based composites, the weave of the material (e.g. unidirectional or plain weave) can determine the extent of the anisotropy of the bulk material. The tunability of orientation of the fibers allows for application-based designs of composite materials, depending on the direction of stresses applied onto the material.
Amorphous materials such as glass and polymers are typically isotropic. Due to the highly randomized orientation of macromolecules in polymeric materials, polymers are in general described as isotropic. However, mechanically gradient polymers can be engineered to have directionally dependent properties through processing techniques or introduction of anisotropy-inducing elements. Researchers have built composite materials with aligned fibers and voids to generate anisotropic hydrogels, in order to mimic hierarchically ordered biological soft matter. 3D printing, especially Fused Deposition Modeling, can introduce anisotropy into printed parts. This is because FDM is designed to extrude and print layers of thermoplastic materials. This creates materials that are strong when tensile stress is applied in parallel to the layers and weak when the material is perpendicular to the layers.
### Microfabrication
Anisotropic etching techniques (such as deep reactive-ion etching) are used in microfabrication processes to create well defined microscopic features with a high aspect ratio. These features are commonly used in MEMS (microelectromechanical systems) and microfluidic devices, where the anisotropy of the features is needed to impart desired optical, electrical, or physical properties to the device. Anisotropic etching can also refer to certain chemical etchants used to etch a certain material preferentially over certain crystallographic planes (e.g., KOH etching of silicon \[100\] produces pyramid-like structures)
### Neuroscience
Diffusion tensor imaging is an MRI technique that involves measuring the fractional anisotropy of the random motion (Brownian motion) of water molecules in the brain. Water molecules located in fiber tracts are more likely to move anisotropically, since they are restricted in their movement (they move more in the dimension parallel to the fiber tract rather than in the two dimensions orthogonal to it), whereas water molecules dispersed in the rest of the brain have less restricted movement and therefore display more isotropy. This difference in fractional anisotropy is exploited to create a map of the fiber tracts in the brains of the individual.
### Remote sensing and radiative transfer modeling {#remote_sensing_and_radiative_transfer_modeling}
Radiance fields (see Bidirectional reflectance distribution function (BRDF)) from a reflective surface are often not isotropic in nature. This makes calculations of the total energy being reflected from any scene a difficult quantity to calculate. In remote sensing applications, anisotropy functions can be derived for specific scenes, immensely simplifying the calculation of the net reflectance or (thereby) the net irradiance of a scene. For example, let the BRDF be $\gamma(\Omega_i, \Omega_v)$ where \'i\' denotes incident direction and \'v\' denotes viewing direction (as if from a satellite or other instrument). And let P be the Planar Albedo, which represents the total reflectance from the scene. $P(\Omega_i) = \int_{\Omega_v} \gamma(\Omega_i, \Omega_v)\hat{n} \cdot d\hat\Omega_v$ $A(\Omega_i, \Omega_v) = \frac{\gamma(\Omega_i, \Omega_v)}{P(\Omega_i)}$
It is of interest because, with knowledge of the anisotropy function as defined, a measurement of the BRDF from a single viewing direction (say, $\Omega_v$) yields a measure of the total scene reflectance (planar albedo) for that specific incident geometry (say, $\Omega_i$).
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Alpha decay
|
thumb\|upright=1.35\|Visual representation of alpha decay `{{Nuclear physics}}`{=mediawiki} **Alpha decay** or **α-decay** is a type of radioactive decay in which an atomic nucleus emits an alpha particle (helium nucleus). The parent nucleus transforms or \"decays\" into a daughter product, with a mass number that is reduced by four and an atomic number that is reduced by two. An alpha particle is identical to the nucleus of a helium-4 atom, which consists of two protons and two neutrons. It has a charge of `{{val|+2|ul=e}}`{=mediawiki} and a mass of `{{val|4|ul=Da}}`{=mediawiki}, and is represented as ${}^{4}_{2}\alpha$. For example, uranium-238 undergoes alpha decay to form thorium-234.
While alpha particles have a charge `{{val|+2|u=e}}`{=mediawiki}, this is not usually shown because a nuclear equation describes a nuclear reaction without considering the electrons -- a convention that does not imply that the nuclei necessarily occur in neutral atoms.
Alpha decay typically occurs in the heaviest nuclides. Theoretically, it can occur only in nuclei somewhat heavier than nickel (element 28), where the overall binding energy per nucleon is no longer a maximum and the nuclides are therefore unstable toward spontaneous fission-type processes. In practice, this mode of decay has only been observed in nuclides considerably heavier than nickel, with the lightest known alpha emitter being the second lightest isotope of antimony, ^104^Sb. Exceptionally, however, beryllium-8 decays to two alpha particles.
Alpha decay is by far the most common form of cluster decay, where the parent atom ejects a defined daughter collection of nucleons, leaving another defined product behind. It is the most common form because of the combined extremely high nuclear binding energy and relatively small mass of the alpha particle. Like other cluster decays, alpha decay is fundamentally a quantum tunneling process. Unlike beta decay, it is governed by the interplay between both the strong nuclear force and the electromagnetic force.
Alpha particles have a typical kinetic energy of 5 MeV (or ≈ 0.13% of their total energy, 110 TJ/kg) and have a speed of about 15,000,000 m/s, or 5% of the speed of light. There is surprisingly small variation around this energy, due to the strong dependence of the half-life of this process on the energy produced. Because of their relatively large mass, the electric charge of `{{val|+2|u=e}}`{=mediawiki} and relatively low velocity, alpha particles are very likely to interact with other atoms and lose their energy, and their forward motion can be stopped by a few centimeters of air.
Approximately 99% of the helium produced on Earth is the result of the alpha decay of underground deposits of minerals containing uranium or thorium. The helium is brought to the surface as a by-product of natural gas production.
## History
Alpha particles were first described in the investigations of radioactivity by Ernest Rutherford in 1899, and by 1907 they were identified as He^2+^ ions. By 1928, George Gamow had solved the theory of alpha decay via tunneling. The alpha particle is trapped inside the nucleus by an attractive nuclear potential well and a repulsive electromagnetic potential barrier. Classically, it is forbidden to escape, but according to the (then) newly discovered principles of quantum mechanics, it has a tiny (but non-zero) probability of \"tunneling\" through the barrier and appearing on the other side to escape the nucleus. Gamow solved a model potential for the nucleus and derived, from first principles, a relationship between the half-life of the decay, and the energy of the emission, which had been previously discovered empirically and was known as the Geiger--Nuttall law.
## Mechanism
The nuclear force holding an atomic nucleus together is very strong, in general much stronger than the repulsive electromagnetic forces between the protons. However, the nuclear force is also short-range, dropping quickly in strength beyond about 3 femtometers, while the electromagnetic force has an unlimited range. The strength of the attractive nuclear force keeping a nucleus together is thus proportional to the number of the nucleons, but the total disruptive electromagnetic force of proton-proton repulsion trying to break the nucleus apart is roughly proportional to the square of its atomic number. A nucleus with 210 or more nucleons is so large that the strong nuclear force holding it together can just barely counterbalance the electromagnetic repulsion between the protons it contains. Alpha decay occurs in such nuclei as a means of increasing stability by reducing size.
One curiosity is why alpha particles, helium nuclei, should be preferentially emitted as opposed to other particles like a single proton or neutron or other atomic nuclei. Part of the reason is the high binding energy of the alpha particle, which means that its mass is less than the sum of the masses of two free protons and two free neutrons. This increases the disintegration energy. Computing the total disintegration energy given by the equation $E_{di} = (m_\text{i} - m_\text{f} - m_\text{p})c^2,$ where `{{math|''m''<sub>i</sub>}}`{=mediawiki} is the initial mass of the nucleus, `{{math|''m''<sub>f</sub>}}`{=mediawiki} is the mass of the nucleus after particle emission, and `{{math|''m''<sub>p</sub>}}`{=mediawiki} is the mass of the emitted (alpha-)particle, one finds that in certain cases it is positive and so alpha particle emission is possible, whereas other decay modes would require energy to be added. For example, performing the calculation for uranium-232 shows that alpha particle emission releases 5.4 MeV of energy, while a single proton emission would *require* 6.1 MeV. Most of the disintegration energy becomes the kinetic energy of the alpha particle, although to fulfill conservation of momentum, part of the energy goes to the recoil of the nucleus itself (see atomic recoil). However, since the mass numbers of most alpha-emitting radioisotopes exceed 210, far greater than the mass number of the alpha particle (4), the fraction of the energy going to the recoil of the nucleus is generally quite small, less than 2%. Nevertheless, the recoil energy (on the scale of keV) is still much larger than the strength of chemical bonds (on the scale of eV), so the daughter nuclide will break away from the chemical environment the parent was in. The energies and ratios of the alpha particles can be used to identify the radioactive parent via alpha spectrometry.
These disintegration energies, however, are substantially smaller than the repulsive potential barrier created by the interplay between the strong nuclear and the electromagnetic force, which prevents the alpha particle from escaping. The energy needed to bring an alpha particle from infinity to a point near the nucleus just outside the range of the nuclear force\'s influence is generally in the range of about 25 MeV. An alpha particle within the nucleus can be thought of as being inside a potential barrier whose walls are 25 MeV above the potential at infinity. However, decay alpha particles only have energies of around 4 to 9 MeV above the potential at infinity, far less than the energy needed to overcome the barrier and escape.
### Quantum tunneling {#quantum_tunneling}
Quantum mechanics, however, allows the alpha particle to escape via quantum tunneling. The quantum tunneling theory of alpha decay, independently developed by George Gamow and by Ronald Wilfred Gurney and Edward Condon in 1928, was hailed as a very striking confirmation of quantum theory. Essentially, the alpha particle escapes from the nucleus not by acquiring enough energy to pass over the wall confining it, but by tunneling through the wall. Gurney and Condon made the following observation in their paper on it:
> It has hitherto been necessary to postulate some special arbitrary \'instability\' of the nucleus, but in the following note, it is pointed out that disintegration is a natural consequence of the laws of quantum mechanics without any special hypothesis\... Much has been written of the explosive violence with which the α-particle is hurled from its place in the nucleus. But from the process pictured above, one would rather say that the α-particle almost slips away unnoticed.
The theory supposes that the alpha particle can be considered an independent particle within a nucleus, that is in constant motion but held within the nucleus by strong interaction. At each collision with the repulsive potential barrier of the electromagnetic force, there is a small non-zero probability that it will tunnel its way out. An alpha particle with a speed of 1.5×10^7^ m/s within a nuclear diameter of approximately 10^−14^ m will collide with the barrier more than 10^21^ times per second. However, if the probability of escape at each collision is very small, the half-life of the radioisotope will be very long, since it is the time required for the total probability of escape to reach 50%. As an extreme example, the half-life of the isotope bismuth-209 is `{{val|2.01|e=19|u=years}}`{=mediawiki}.
The isotopes in beta-decay stable isobars that are also stable with regards to double beta decay with mass number *A* = 5, *A* = 8, 143 ≤ *A* ≤ 155, 160 ≤ *A* ≤ 162, and *A* ≥ 165 are theorized to undergo alpha decay. All other mass numbers (isobars) have exactly one theoretically stable nuclide. Those with mass 5 decay to helium-4 and a proton or a neutron, and those with mass 8 decay to two helium-4 nuclei; their half-lives (helium-5, lithium-5, and beryllium-8) are very short, unlike the half-lives for all other such nuclides with *A* ≤ 209, which are very long. (Such nuclides with *A* ≤ 209 are primordial nuclides except ^146^Sm.)
Working out the details of the theory leads to an equation relating the half-life of a radioisotope to the decay energy of its alpha particles, a theoretical derivation of the empirical Geiger--Nuttall law.
## Uses
Americium-241, an alpha emitter, is used in smoke detectors. The alpha particles ionize air in an open ion chamber and a small current flows through the ionized air. Smoke particles from the fire that enter the chamber reduce the current, triggering the smoke detector\'s alarm.
Radium-223 is also an alpha emitter. It is used in the treatment of skeletal metastases (cancers in the bones).
Alpha decay can provide a safe power source for radioisotope thermoelectric generators used for space probes and were used for artificial heart pacemakers. Alpha decay is much more easily shielded against than other forms of radioactive decay.
Static eliminators typically use polonium-210, an alpha emitter, to ionize the air, allowing the \"static cling\" to dissipate more rapidly.
## Toxicity
Highly charged and heavy, alpha particles lose their several MeV of energy within a small volume of material, along with a very short mean free path. This increases the chance of double-strand breaks to the DNA in cases of internal contamination, when ingested, inhaled, injected or introduced through the skin. Otherwise, touching an alpha source is typically not harmful, as alpha particles are effectively shielded by a few centimeters of air, a piece of paper, or the thin layer of dead skin cells that make up the epidermis; however, many alpha sources are also accompanied by beta-emitting radio daughters, and both are often accompanied by gamma photon emission.
Relative biological effectiveness (RBE) quantifies the ability of radiation to cause certain biological effects, notably either cancer or cell-death, for equivalent radiation exposure. Alpha radiation has a high linear energy transfer (LET) coefficient, which is about one ionization of a molecule/atom for every angstrom of travel by the alpha particle. The RBE has been set at the value of 20 for alpha radiation by various government regulations. The RBE is set at 10 for neutron irradiation, and at 1 for beta radiation and ionizing photons.
However, the recoil of the parent nucleus (alpha recoil) gives it a significant amount of energy, which also causes ionization damage (see ionizing radiation). This energy is roughly the weight of the alpha (`{{val|4|ul=Da}}`{=mediawiki}) divided by the weight of the parent (typically about 200 Da) times the total energy of the alpha. By some estimates, this might account for most of the internal radiation damage, as the recoil nucleus is part of an atom that is much larger than an alpha particle, and causes a very dense trail of ionization; the atom is typically a heavy metal, which preferentially collect on the chromosomes. In some studies, this has resulted in an RBE approaching 1,000 instead of the value used in governmental regulations.
The largest natural contributor to public radiation dose is radon, a naturally occurring, radioactive gas found in soil and rock. If the gas is inhaled, some of the radon particles may attach to the inner lining of the lung. These particles continue to decay, emitting alpha particles, which can damage cells in the lung tissue. The death of Marie Curie at age 66 from aplastic anemia was probably caused by prolonged exposure to high doses of ionizing radiation, but it is not clear if this was due to alpha radiation or X-rays. Curie worked extensively with radium, which decays into radon, along with other radioactive materials that emit beta and gamma rays. However, Curie also worked with unshielded X-ray tubes during World War I, and analysis of her skeleton during a reburial showed a relatively low level of radioisotope burden.
The Russian defector Alexander Litvinenko\'s 2006 murder by radiation poisoning is thought to have been carried out with polonium-210, an alpha emitter.
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Extreme poverty
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\[\[<File:World-population-in-extreme-poverty-absolute.svg%7Cthumb%7Cupright=1.6%7CNumber> of people living in extreme poverty from 1820 to 2015.
\]\] thumb\|upright=1.6\|Total population living in extreme poverty, by world region 1990 to 2015. `{{legend|#97cb72|Latin America and Caribbean}}`{=mediawiki} `{{legend|#eb6d6a|East Asia and Pacific Islands}}`{=mediawiki} `{{legend|#facfaf|South Asia}}`{=mediawiki} `{{legend|#6ab3b8|Middle East and North Africa}}`{=mediawiki} `{{legend|#ffe178|Europe and Central Asia}}`{=mediawiki} `{{legend|#6f8fc2|Sub-Saharan Africa}}`{=mediawiki} `{{legend|#b890ba|Other high income countries}}`{=mediawiki} thumb\|upright=1.6\|The number of people living on less than \$1.90, \$3.20, \$5.50, and \$10 globally from 1981 to 2015. `{{legend|#70b678|More than $10 a day}}`{=mediawiki} `{{legend|#badaac|$5.50 to $10 a day}}`{=mediawiki} `{{legend|#fddf75|$3.20 to $5.50 a day}}`{=mediawiki} `{{legend|#da6668|$1.90 to $3.20 a day}}`{=mediawiki} `{{legend|#6f8fc2|Less than $1.90 a day}}`{=mediawiki}
**Extreme poverty** is the most severe type of poverty, defined by the United Nations (UN) as \"a condition characterized by severe deprivation of basic human needs, including food, safe drinking water, sanitation facilities, health, shelter, education and information. It depends not only on income but also on access to services\". Historically, other definitions have been proposed within the United Nations.
Extreme poverty mainly refers to an income below the international poverty line of \$1.90 per day in 2018 (\$`{{format price|{{Inflation|US|1.90|2011|r=2}}}}`{=mediawiki} in `{{Inflation-year|US}}`{=mediawiki} dollars),`{{Inflation-fn|US}}`{=mediawiki} set by the World Bank. This is the equivalent of \$1.00 a day in 1996 US prices, hence the widely used expression \"living on less than a dollar a day\". The vast majority of those in extreme poverty reside in South Asia and Sub-Saharan Africa. As of 2018, it is estimated that the country with the most people living in extreme poverty is Nigeria, at 86 million.
In the past, the vast majority of the world population lived in conditions of extreme poverty. The percentage of the global population living in absolute poverty fell from over 80% in 1800 to around 10% by 2015. According to UN estimates, `{{as of|alt=in 2015|2015}}`{=mediawiki} roughly 734 million people or 10% remained under those conditions. The number had previously been measured as 1.9 billion in 1990, and 1.2 billion in 2008. Despite the significant number of individuals still below the international poverty line, these figures represent significant progress for the international community, as they reflect a decrease of more than one billion people over 15 years.
In public opinion surveys around the globe, people surveyed tend to think that extreme poverty has not decreased.
The reduction of extreme poverty and hunger was the first Millennium Development Goal (MDG1), as set by the United Nations in 2000. Specifically, the target was to reduce the extreme poverty rate by half by 2015, a goal that was met five years ahead of schedule. In the Sustainable Development Goals, which succeeded the MDGs, the goal is to end extreme poverty in all its forms everywhere. With this declaration the international community, including the UN and the World Bank have adopted the target of ending extreme poverty by 2030.
## Definition
### Previous definitions {#previous_definitions}
In July 1993, Leandro Despouy, the then UN Special Rapporteur on extreme poverty and human rights made use of a definition he adapted from a 1987 report to the French Economic and Social Council by Fr. Joseph Wresinski, founder of the International Movement ATD Fourth World, distinguishing \"lack of basic security\" (poverty) and \"chronic poverty\" (extreme poverty), linking the eradication of extreme poverty by allowing people currently experiencing it a real opportunity to exercise all their human rights:
This definition was mentioned previously, in June 1989, in the preliminary report on the realization of economic, social and cultural rights by the UN Special Rapporteur Danilo Türk. It is still in use today, among others, in the current UN Guiding Principles on Extreme Poverty and Human Rights adopted by the UN Human Rights Council in September 2012.
### Consumption-based definition {#consumption_based_definition}
Extreme poverty is defined by the international community as living below \$1.90 a day, as measured in 2011 international prices (equivalent to \$2.12 in 2018). This number, also known as the international poverty line, is periodically updated to account for inflation and differences in the cost of living; it was originally defined at \$1.00 a day in 1996. The updates are made according to new price data to portray the costs of basic food, health services, clothing, and shelter around the world as accurately as possible. The latest revision was made in 2015 when the World Bank increased the line to international-\$1.90.
Because many of the world\'s poorest people do not have a monetary income, the poverty measurement is based on the monetary value of a person\'s *consumption*. Otherwise the poverty measurement would be missing the home production of subsistence farmers that consume largely their own production.
### Alternative definitions {#alternative_definitions}
thumb\|upright=1.6\|Share of population living in multidimensional poverty in 2014 The \$1.90/day extreme poverty line remains the most widely used metric as it highlights the reality of those in the most severe conditions. Although widely used by most international organizations, it has come under scrutiny due to a variety of factors. For example, it does not account for how far below the line people are, referred to as the depth of poverty. For this purpose, the same institutions publish data on the poverty gap.
The international poverty line is designed to stay constant over time, to allow comparisons between different years. It is therefore a measure of absolute poverty and is not measuring relative poverty. It is also not designed to capture how people view their own financial situation (known as the socially subjective poverty line). Moreover, the calculation of the poverty line relies on information about consumer prices to calculate purchasing power parity, which are very hard to measure and are necessarily debatable. As with all other metrics, there may also be missing data from the poorest and most fragile countries.
Several alternative instruments for measuring extreme poverty have been suggested which incorporate other factors such as malnutrition and lack of access to a basic education. The Multidimensional Poverty Index (MPI), based on the Alkire-Foster Method, is published by the Oxford Poverty & Human Development Initiative (OPHI): it measures deprivation in basic needs and can be broken down to reflect both the incidence and the intensity of poverty. For example, under conventional measures, in both Ethiopia and Uzbekistan about 40% of the population is considered extremely poor, but based on the MPI, 90% of Ethiopians but only 2% of Uzbeks are in multidimensional poverty.
The MPI is useful for development officials to determine the most likely causes of poverty within a region, using the M0 measure of the method (which is calculated by multiplying the fraction of people in poverty by the fraction of dimensions they are deprived in). For example, in the Gaza Strip of Palestine, using the M0 measure of the Alkire-Foster method reveals that poverty in the region is primarily caused by a lack of access to electricity, lack of access to drinking water, and widespread overcrowding. In contrast, data from the Chhukha District of Bhutan reveals that income is a much larger contributor to poverty as opposed to other dimensions within the region. However, the MPI only presents data from 105 countries, so it cannot be used for global measurements.
## Share of the population living in extreme poverty {#share_of_the_population_living_in_extreme_poverty}
Region 1990 1995 2000 2005 2010 2015 2017
---------------------------- ----------- ----------- ----------- ----------- ----------- ------------ ------------
Developed countries 4.06 4.99 4.7 5.48 5.28 7.91 7.45
Latin America & Caribbean 66.61 64.75 65.77 54.04 35.3 22.95 23.73
Middle East & North Africa 14.8 16.49 9.95 9.6 6.86 15.74 24.16
South Asia 557.05 550.44 564.92 533.28 425.32 230.51 173.1
East Asia & Pacific 977.29 766.14 632.26 347.99 212.12 42.08 29.15
Europe & Central Asia 11.51 32 34.28 22.04 11.27 7.35 6.37
Sub-Saharan Africa 280.95 352.76 388.27 393.57 412.49 417.6 432.5
**Total** **1,910** **1,790** **1,700** **1,370** **1,110** **744.14** **696.45**
: Number of people pushed below the \$1.90 (\$2011 PPP) poverty line (in millions) \|+
## Current trends {#current_trends}
### Getting to zero {#getting_to_zero}
upright=2.0\|right\|thumb\|Various projections for the prospect of ending extreme poverty by 2030. The *y*-axis represents the percentage of people living in extreme poverty worldwide.
Using the World Bank definition of \$1.90/day, `{{as of|2021|lc=y}}`{=mediawiki}, roughly 710 million people remained in extreme poverty (or roughly 1 in 10 people worldwide). Nearly half of them live in India and China, with more than 85% living in just 20 countries. Since the mid-1990s, there has been a steady decline in both the worldwide poverty rate and the total number of extreme poor. In 1990, the percentage of the global population living in extreme poverty was 43%, but in 2011, that percentage had dropped down to 21%. This halving of the extreme poverty rate falls in line with the first Millennium Development Goal (MDG1) proposed by former UN Secretary-General Kofi Annan, who called on the international community at the turn of the century to reduce the percentage of people in extreme poverty by half by 2015.
This reduction in extreme poverty took place most notably in China, Indonesia, India, Pakistan and Vietnam. These five countries accounted for the alleviation of 715 million people out of extreme poverty between 1990 and 2010 -- more than the global net total of roughly 700 million. This statistical oddity can be explained by the fact that the number of people living in extreme poverty in Sub-Saharan Africa rose from 290 million to 414 million over the same period. However, there have been many positive signs for extensive, global poverty reduction as well. Since 1999, the total number of extreme poor has declined by an average of 50 million per year. Moreover, in 2005, for the first time in recorded history, poverty rates began to fall in every region of the world, including Africa.
As aforementioned, the number of people living in extreme poverty has reduced from 1.9 billion to 766 million over the span of the last decades. If we remain on our current trajectory, many economists predict we could reach global zero by 2030--2035, thus ending extreme poverty. Global zero entails a world in which fewer than 3% of the global population lives in extreme poverty (projected under most optimistic scenarios to be fewer than 200 million people). This zero figure is set at 3% in recognition of the fact that some amount of frictional (temporary) poverty will continue to exist, whether it is caused by political conflict or unexpected economic fluctuations, at least for the foreseeable future. However, the Brookings Institution notes that any projection about poverty more than a few years into the future runs the risk of being highly uncertain. This is because changes in consumption and distribution throughout the developing world over the next two decades could result in monumental shifts in global poverty, for better or worse.
Others are more pessimistic about this possibility, predicting a range of 193 million to 660 million people still living in extreme poverty by 2035. Additionally, some believe the rate of poverty reduction will slow down in the developing world, especially in Africa, and as such it will take closer to five decades to reach global zero. Despite these reservations, several prominent international and national organizations, including the UN, the World Bank and the United States Federal Government (via USAID), have set a target of reaching global zero by the end of 2030.
More recent analyses in 2022 on real wages have questioned whether extreme poverty was a \"natural\" condition of humanity and decreased with the rise of capitalism.
upright=1.4\|thumb\|Reduction in global poverty by year in percentage points
### Exacerbating factors {#exacerbating_factors}
There are a variety of factors that may reinforce or instigate the existence of extreme poverty, such as weak institutions, cycles of violence and a low level of growth. Recent World Bank research shows that some countries can get caught in a \"fragility trap\", in which self-reinforcing factors prevent the poorest nations from emerging from low-level equilibrium in the long run. Moreover, most of the reduction in extreme poverty over the past twenty years has taken place in countries that have not experienced a civil conflict or have had governing institutions with a strong capacity to actually govern. Thus, to end extreme poverty, it is also important to focus on the interrelated problems of fragility and conflict.
USAID defines fragility as a government\'s lack of both legitimacy (the perception the government is adequate at doing its job) and effectiveness (how good the government is at maintaining law and order, in an equitable manner). As fragile nations are unable to equitably and effectively perform the functions of a state, these countries are much more prone to violent unrest and mass inequality. Additionally, in countries with high levels of inequality (a common problem in countries with inadequate governing institutions), much higher growth rates are needed to reduce the rate of poverty when compared with other nations. Additionally, if China and India are removed from the equation, up to 70% of the world\'s poor live in fragile states by some definitions of fragility. Some analysts project that extreme poverty will be increasingly concentrated in fragile, low-income states like Haiti, Yemen and the Central African Republic. However, some academics, such as Andy Sumner, say that extreme poverty will be increasingly concentrated in middle-income countries, creating a paradox where the world\'s poor do not actually live in the poorest countries.
To help low-income earners, fragile states make the transition towards peace and prosperity, the New Deal for Engagement in Fragile States, endorsed by roughly forty countries and multilateral institutions, was created in 2011. This represents an important step towards redressing the problem of fragility as it was originally articulated by self-identified fragile states who called on the international community to not only \"do things differently\", but to also \"do different things\".
Civil conflict also remains a prime cause for the perpetuation of poverty throughout the developing world. Armed conflict can have severe effects on economic growth for many reasons such as the destruction of assets, destruction of livelihoods, creation of unwanted mass migration, and diversion of public resources towards war. Significantly, a country that experienced major violence during 1981--2005 had extreme poverty rates 21 percentage points higher than a country with no violence. On average, each civil conflict will cost a country roughly 30 years of GDP growth. Therefore, a renewed commitment from the international community to address the deteriorating situation in highly fragile states is necessary to both prevent the mass loss of life, but to also prevent the vicious cycle of extreme poverty.
Population trends and dynamics (e.g. population growth) can also have a large impact on prospects for poverty reduction. According to the United Nations, \"in addition to improving general health and well-being, analysis shows that meeting the reproductive health and contraceptive needs of all women in the developing world more than pays for itself\").
In 2013, a prominent finding in a report by the World Bank was that extreme poverty is most prevalent in low-income countries. In these countries, the World Bank found that progress in poverty reduction is the slowest, the poor live under the worst conditions, and the most affected persons are children age 12 and under.
## International initiatives {#international_initiatives}
### Millennium Summit and Millennium Development Goals {#millennium_summit_and_millennium_development_goals}
In September 2000, world leaders gathered at the Millennium Summit held in New York, launching the United Nations Millennium Project suggested by then UN Secretary-General Kofi Annan. Prior to the launch of the conference, the office of Secretary-General Annan released a report entitled \"We The Peoples: The Role of the United Nations in the 21st Century\". In this document, now widely known as the Millennium Report, Kofi Annan called on the international community to reduce the proportion of people in extreme poverty by half by 2015, a target that would affect over 1 billion people. Citing the close correlation between economic growth and the reduction of poverty in poor countries, Annan urged international leaders to indiscriminately target the problem of extreme poverty across every region. In charge of managing the project was Jeffrey Sachs, a noted development economist, who in 2005 released a plan for action called \"Investing in Development: A Practical Plan to Achieve the Millennium Development Goals\". Thomas Pogge criticized the 2000 Millennium Declaration for being less ambitious than a previous declaration from the World Food Summit due to using 1990 as the benchmark rather than 1996.
Overall, there has been significant progress towards reducing extreme poverty, with the MDG1 target of reducing extreme poverty rates by half being met five years early, representing 700 million people being lifted out of extreme poverty from 1990 to 2010, with 1.2 billion people still remaining under those conditions. The notable exception to this trend was in Sub-Saharan Africa, the only region where the number of people living in extreme poverty rose from 290 million in 1990 to 414 million in 2010, comprising more than a third of those living in extreme poverty worldwide.
#### 2005 World Summit {#world_summit}
The 2005 World Summit, held in September which was organized to measure international progress towards fulfilling the Millennium Development Goals (MDGs). Notably, the conference brought together more than 170 Heads of State. While world leaders at the summit were encouraged by the reduction of poverty in some nations, they were concerned by the uneven decline of poverty within and among different regions of the globe. However, at the end of the summit, the conference attendees reaffirmed the UN\'s commitment to achieve the MDGs by 2015 and urged all supranational, national and non-governmental organizations to follow suit.
### Sustainable Development Goals {#sustainable_development_goals}
As the expiration of the Millennium Development Goals approached in 2015, the UN convened a panel to advise on a Post-2015 Development Agenda, which led to a new set of 17 goals for 2030 titled the Sustainable Development Goals (SDGs). The first goal (SDG 1) is to \"End poverty in all its forms everywhere.\"
The HLP report, entitled A New Global Partnership: Eradicate Poverty and Transform Economies Through Sustainable Development, was published in May 2013. In the report, the HLP wrote that:
> Ending extreme poverty is just the beginning, not the end. It is vital, but our vision must be broader: to start countries on the path of sustainable development -- building on the foundations established by the 2012 UN Conference on Sustainable Development in Rio de Janeiro, and meeting a challenge that no country, developed or developing, has met so far. We recommend to the Secretary-General that deliberations on a new development agenda must be guided by the vision of eradicating extreme poverty once and for all, in the context of sustainable development.
Therefore, the report determined that a central goal of the Post-Millennium Development agenda is to eradicate extreme poverty by 2030. However, the report also emphasized that the MDGs were not enough on their own, as they did not \"focus on the devastating effects of conflict and violence on development \... the importance to development of good governance and institution \... nor the need for inclusive growth\...\" Consequently, there now exists synergy between the policy position papers put forward by the United States (through USAID), the World Bank and the UN itself in terms of viewing fragility and a lack of good governance as exacerbating extreme poverty. However, in a departure from the views of other organizations, the commission also proposed that the UN focus not only on extreme poverty (a line drawn at \$1.25), but also on a higher target, such as \$2. The report notes this change could be made to reflect the fact that escaping extreme poverty is only a first step.
In addition to the UN, a host of other supranational and national actors such as the European Union and the African Union have published their own positions or recommendations on what should be incorporated in the Post-2015 agenda. The European Commission\'s communication, published in A decent Life for all: from vision to collective action, affirmed the UN\'s commitment to \"eradicate extreme poverty in our lifetime and put the world on a sustainable path to ensure a decent life for all by 2030\". A unique vision of the report was the commission\'s environmental focus (in addition to a plethora of other goals such as combating hunger and gender inequality). Specifically, the Commission argued, \"long-term poverty reduction \... requires inclusive and sustainable growth. Growth should create decent jobs, take place with resource efficiency and within planetary boundaries, and should support efforts to mitigate climate change.\" The African Union\'s report, entitled Common African Position (CAP) on the Post-2015 Development Agenda, likewise encouraged the international community to focus on eradicating the twin problems of poverty and exclusion in our lifetime. Moreover, the CAP pledged that \"no person -- regardless of ethnicity, gender, geography, disability, race or other status -- is denied universal human rights and basic economic opportunities\".
### Least developed country conferences {#least_developed_country_conferences}
The UN least developed country (LDC) conferences were a series of summits organized by the UN to promote the substantial and even development of the world\'s least developed countries.
## Organizations working to end extreme poverty {#organizations_working_to_end_extreme_poverty}
### International organizations {#international_organizations}
#### World Bank {#world_bank}
In 2013, the Board of Governors of the World Bank Group (WBG) set two overriding goals for the WBG to commit itself to in the future. First, to end extreme poverty by 2030, an objective that echoes the sentiments of the UN and the Obama administration. Additionally, the WBG set an interim target of reducing extreme poverty to below 9% by 2020. Second, to focus on growth among the bottom 40% of people, as opposed to standard GDP growth. This commitment ensures that the growth of the developing world lifts people out of poverty, rather than exacerbating inequality.
As the World Bank\'s primary focus is on delivering economic growth to enable equitable prosperity, its developments programs are primarily commercial-based in nature, as opposed to the UN. Since the World Bank recognizes better jobs will result in higher income, and thus less poverty, the WBG seeks to support employment training initiatives, small business development programs and strong labor protection laws. However, since much of the growth in the developing world has been inequitable, the World Bank has also begun teaming with client states to map out trends in inequality and to propose public policy changes that can level the playing field.
Moreover, the World Bank engages in a variety of nutritional, transfer payments and transport-based initiatives. Children who experience under-nutrition from conception to two years of age have a much higher risk of physical and mental disability. Thus, they are often trapped in poverty and are unable to make a full contribution to the social and economic development of their communities as adults. The WBG estimates that as much as 3% of GDP can be lost as a result of under-nutrition among the poorest nations. To combat undernutrition, the WBG has partnered with UNICEF and the WHO to ensure all small children are fully fed. The WBG also offers conditional cash transfers to poor households who meet certain requirements such as maintaining children\'s healthcare or ensuring school attendance. Finally, the WBG understands investment in public transportation and better roads is key to breaking rural isolation, improving access to healthcare and providing better job opportunities for the World\'s poor.
#### United Nations {#united_nations}
The UN Office for the Coordination of Humanitarian Affairs (OCHA) works to synchronize the disparate international, national and non-governmental efforts to contest poverty. OCHA seeks to prevent \"confusion\" in relief operations and to ensure that the humanitarian response to disaster situations has greater accountability and predictability. To do so, OCHA has begun deploying Humanitarian Coordinators and Country Teams to provide a solid architecture for the international community to work through.
The United Nation\'s Children\'s Fund (UNICEF) was created by the UN to provide food, clothing and healthcare to European children facing famine and disease in the immediate aftermath of World War II. After the UN General Assembly extended UNICEF\'s mandate indefinitely in 1953, it actively worked to help children in extreme poverty in more than 190 countries and territories to overcome the obstacles that poverty, violence, disease and discrimination place in a child\'s path. Its current focus areas are 1) Child survival & development 2) Basic education & gender equality 3) Children and HIV/AIDS and 4) Child protection.
The UN Refugee Agency (UNHCR) is mandated to lead and coordinate international action to protect refugees worldwide. Its primary purpose is to safeguard the rights of refugees by ensuring anyone can exercise the right to seek asylum in another state, with the option to return home voluntarily, integrate locally or resettle in a third country. The UNHCR operates in over 125 countries, helping approximately 33.9 million persons.
The World Food Programme (WFP) is the largest agency dedicated to fighting hunger worldwide. On average, the WFP brings food assistance to more than 90 million people in 75 countries. The WFP not only strives to prevent hunger in the present, but also in the future by developing stronger communities which will make food even more secure on their own. The WFP has a range of expertise from Food Security Analysis, Nutrition, Food Procurement and Logistics.
The World Health Organization (WHO) is responsible for providing leadership on global health matters, shaping the health research agenda, articulating evidence-based policy decisions and combating diseases that are induced from poverty, such as HIV/AIDS, malaria and tuberculosis. Moreover, the WHO deals with pressing issues ranging from managing water safety, to dealing with maternal and newborn health.
### Governmental agencies {#governmental_agencies}
#### USAID
The US Agency for International Development (USAID) is the lead US government agency dedicated to ending extreme poverty. Currently the largest bilateral donor in the world, the United States channels the majority of its development assistance through USAID and the US Department of State. In President Obama\'s 2013 State of the Union address, he declared, \"So the United States will join with our allies to eradicate such extreme poverty in the next two decades \... which is within our reach.\" In response to Obama\'s call to action, USAID has made ending extreme poverty central to its mission statement. Under its New Model of Development, USAID seeks to eradicate extreme poverty through the use of innovation in science and technology, by putting a greater emphasis on evidence based decision-making, and through leveraging the ingenuity of the private sector and global citizens.
A major initiative of the Obama administration is Power Africa, which aims to bring energy to 20 million people in Sub-Saharan Africa. By reaching out to its international partners, whether commercial or public, the US has leveraged over \$14 billion in outside commitments after investing only US\$7 billion of its own. To ensure that Power Africa reaches the region\'s poorest, the initiative engages in a transaction based approach to create systematic change. This includes expanding access to electricity to more than 20,000 additional households which already live without power.
In terms of specific programming, USAID works in a variety of fields from preventing hunger, reducing HIV/AIDS, providing general health assistance and democracy assistance, as well as dealing with gender issues. To deal with food security, which affects roughly 842 million people (who go to bed hungry each night), USAID coordinates the Feed the Future Initiative (FtF). FtF aims to reduce poverty and under-nutrition each by 20% over five years. Because of the President\'s Emergency Plan for AIDS Relief (PEPFAR) and a variety of congruent actors, the incidence of AIDS and HIV, which used to ravage Africa, reduced in scope and intensity. Through PEPFAR, the United States has ensured over five million people have received life-saving antiviral drugs, a significant proportion of the eight million people receiving treatment in relatively poor nations.
In terms of general health assistance, USAID has worked to reduce maternal mortality by 30%, under-five child mortality by 35%, and has accomplished a host of other goals. USAID also supports the gamut of democratic initiatives, from promoting human rights and accountable, fair governance, to supporting free and fair elections and the rule of law. In pursuit of these goals, USAID has increased global political participation by training more than 9,800 domestic election observers and providing civic education to more than 6.5 million people. Since 2012, the Agency has begun integrating critical gender perspectives across all aspects of its programming to ensure all USAID initiatives work to eliminate gender disparities. To do so, USAID seeks to increase the capability of women and girls to realize their rights and determine their own life outcomes. Moreover, USAID supports additional programs to improve women\'s access to capital and markets, builds theirs skills in agriculture, and supports women\'s desire to own businesses.
#### Others
Other major government development agencies with annual aid programmes of more than \$10 billion include: GIZ (Germany), FCDO (United Kingdom), JICA (Japan), European Union and AFD (France).
### Non-Governmental Organizations {#non_governmental_organizations}
A multitude of non-governmental organizations operate in the field of extreme poverty, actively working to alleviate the poorest of the poor of their deprivation. To name but a few notable organizations: Save the Children, the Overseas Development Institute, Concern Worldwide, ONE, Trickle Up and Oxfam have all done a considerable amount of work in extreme poverty.
Save the Children is the leading international organization dedicated to helping the world\'s indigent children. In 2013, Save the Children reached over 143 million children through their work, including over 52 million children directly. Save the Children also recently released their own report titled \"Getting to Zero\", in which they argued the international community could feasibly do more than lift the world\'s poor above \$1.25/day.
The Overseas Development Institute (ODI) is a UK based think tank on international development and humanitarian issues. ODI is dedicated to alleviating the suffering of the world\'s poor by providing high-quality research and practical policy advice to the World\'s development officials. ODI also recently released a paper entitled, \"The Chronic Poverty Report 2014--2015: The road to zero extreme poverty\", in which its authors assert that though the international communities\' goal of ending extreme poverty by 2030 is laudable, much more targeted resources will be necessary to reach said target. The report states that \"To eradicate extreme poverty, massive global investment is required in social assistance, education and pro-poorest economic growth\".
Concern Worldwide is an international humanitarian organization whose mission is to end extreme poverty by influencing decision makers at all levels of government (from local to international). Concern has also produced a report on extreme poverty in which they explain their own conception of extreme poverty from a NGO\'s standpoint. In this paper, named \"How Concern Understands Extreme Poverty\", the report\'s creators write that extreme poverty entails more than just living under \$1.25/day, it also includes having a small number of assets and being vulnerable to severe negative shocks (whether natural or man made).
ONE, the organization co-founded by Bono, is a non-profit organization funded almost entirely by foundations, individual philanthropists and corporations. ONE\'s goals include raising public awareness and working with political leaders to fight preventable diseases, increase government accountability and increase investment in nutrition. Finally, Trickle Up is a micro-enterprise development program targeted at those living on under \$1.25/day, which provides the indigent with resources to build a sustainable livelihood through both direct financing and considerable training efforts.
Oxfam is a non-governmental organization that works prominently in Africa; their mission is to improve local community organizations and it works to reduce impediments to the development of the country. Oxfam helps families suffering from poverty receive food and healthcare to survive. There are many children in Africa experiencing growth stunting, and this is one example of an issue that Oxfam targets and aims to resolve.
Cash transfers appear to be an effective intervention for reducing extreme poverty, while at the same time improving health and education outcomes.
#### Campaigns
- Giving What We Can
- Global Poverty Project
- Live Below the Line
- Make Poverty History
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Geography of Antarctica
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The **geography of Antarctica** is dominated by its south polar location and, thus, by ice. The Antarctic continent, located in the Earth\'s southern hemisphere, is centered asymmetrically around the South Pole and largely south of the Antarctic Circle. It is washed by the Southern (or Antarctic) Ocean or, depending on definition, the southern Pacific, Atlantic, and Indian Oceans. It has an area of more than 14200000 sqkm. Antarctica is the largest ice desert in the world.
Some 98% of Antarctica is covered by the Antarctic ice sheet, the world\'s largest ice sheet and also its largest reservoir of fresh water. Averaging at least 1.6 km thick, the ice is so massive that it has depressed the continental bedrock in some areas more than 2.5 km below sea level; subglacial lakes of liquid water also occur (e.g. Lake Vostok). Ice shelves and rises populate the ice sheet on the periphery. The present Antarctic ice sheet accounts for 90 percent of Earth\'s total ice volume and 70 percent of its fresh water. It houses enough water to raise global sea level by 200 ft.
In September 2018, researchers at the National Geospatial-Intelligence Agency released a high resolution terrain map (detail down to the size of a car, and less in some areas) of Antarctica, named the \"Reference Elevation Model of Antarctica\" (REMA).
## Regions
Physically, Antarctica is divided in two by the Transantarctic Mountains, close to the neck between the Ross Sea and the Weddell Sea. Western Antarctica and Eastern Antarctica correspond roughly to the western and eastern hemispheres relative to the Greenwich meridian.
West Antarctica is covered by the West Antarctic Ice Sheet. There has been some concern about this ice sheet, as there is a small chance it will collapse due to rising temperatures in the region. If it does, global ocean levels will rise by a few metres in a short period of time.
## Volcanoes
Volcanic activity occurring beneath glacial ice sheets is known as glaciovolcanism. An article published in 2017 claims that researchers from the University of Edinburgh discovered 91 new volcanoes below the Antarctic ice sheet, adding to the 47 volcanoes that were already known. As of 2017, 138 possible volcanoes have been identified in West Antarctica. There is limited knowledge about West Antarctic Volcanoes due to the presence of the West Antarctic Ice Sheet, which heavily covers the West Antarctic Rift System --- a likely hub for volcanic activity. Researchers find it difficult to properly identify volcanic activity due to the comprehensive ice covering.
East Antarctica is significantly larger than West Antarctica, and similarly remains widely unexplored in terms of its volcanic potential. While there are some indications that there is volcanic activity under the East Antarctic Ice Sheet, there is not a significant amount of present information on the subject.
Mount Erebus, as the southernmost historically active volcanic site on the planet, is one of the most notable sites in the study of Antarctic volcanism.
Deception Island is another active Antarctic volcano. It is one of the most protected areas in the Antarctic, given its situation between the South Shetland Islands and the Antarctic Peninsula. As the most active volcano in the Antarctic Peninsula, it has been studied closely since its initial discovery in 1820.
There are four volcanoes on the mainland of Antarctica that are considered to be active on the basis of observed fumarolic activity or \"recent\" tephra deposits:
1. Mount Melbourne (2,730 m) (74°21\'S., 164°42\'E.), a stratovolcano;
2. Mount Berlin (3,500 m) (76°03\'S., 135°52\'W.), a stratovolcano;
3. Mount Kauffman (2,365 m) (75°37\'S., 132°25\'W.), a stratovolcano; and
4. Mount Hampton (3,325 m) (76°29\'S., 125°48\'W.), a volcanic caldera.
Mount Rittmann (2,600 m) (73.45°S 165.5° E), a volcanic caldera, is dormant.
Several volcanoes on offshore islands have records of historic activity. Mount Erebus (3,795 m), a stratovolcano on Ross Island with 10 known eruptions and 1 suspected eruption. On the opposite side of the continent, Deception Island (62°57\'S., 60°38\'W.), a volcanic caldera with 10 known and 4 suspected eruptions, has been the most active. Buckle Island in the Balleny Islands (66°50\'S., 163°12\'E.), Penguin Island (62°06\'S., 57°54\'W.), Paulet Island (63°35\'S., 55°47\'W.), and Lindenberg Island (64°55\'S., 59°40\'W.) are also considered to be active. In 2017, the researchers of Edinburgh University discovered 91 underwater volcanoes under West Antarctica.
### Marie Byrd Land {#marie_byrd_land}
Marie Byrd Land makes up a large portion of West Antarctica, consisting of the Area below the Antarctic Peninsula. The Marie Byrd Land is a large formation of volcanic rock, characterized by 18 exposed and subglacial volcanoes. 16 of the 18 volcanoes are entirely covered by the antarctic ice sheet. There have been no eruptions recorded from any of the volcanoes in this area, however scientists believe that some of the volcanoes may be potentially active.
### Activity
Scientists and researchers debate whether or not the 138 identified possible volcanoes are active or dormant. It is very hard to definitively say, given that many of these volcanic structures are buried underneath several kilometers of ice. However, ash layers within the West Antarctic Ice Sheet, as well as deformations in the ice surface indicate that the West Antarctic Rift System could be active and contain erupting volcanoes. Additionally, seismic activity in the region hints at magma movement beneath the crust, a sign of volcanic activity. Despite this, however, there is not yet definitive evidence of presently active volcanoes.
Subglacial volcanism is often characterized by ice melt and subglacial water. Though there are other sources of subglacial water, such as geothermal heat, it almost always is a condition of volcanism. Scientists remain uncertain about the presence of liquid water underneath the West Antarctic Ice Sheet, with some claiming to have found evidence indicating its existence.
### Conditions of formation {#conditions_of_formation}
In West Antarctica\'s Marie Byrd Land, volcanoes are typically composed of alkaline and basaltic lava. Sometimes, the volcanoes are entirely basaltic in composition. Due to the geographic similarity of the Marie Byrd Land, it is believed that the volcanoes in the West Antarctic Rift System are also composed of basalt.
Above-ice basaltic volcanoes, also known as subaerial basaltic volcanoes, generally form in tall, broad cone shapes. Since they are formed from repeated piling of liquid magma sourced from the center, they spread widely and grow upwards relatively slowly. However, West Antarctic Volcanoes form underneath ice sheets, and are thus categorized as subglacial volcanoes. Subglacial volcanoes that are monogenetic are far more narrow, steeper, flat topped structures. Polygenetic subglacial volcanoes have a wider variety of shapes and sizes due to being made up of many different eruptions. Often, they look more cone shaped, like stratovolcanoes.
### Hazards
#### Hazardous ash {#hazardous_ash}
Little has been studied about the implications of volcanic ash from eruptions within the Antarctic Circle. It is likely that an eruption at lower latitudes would cause global health and aviation hazards due to ash disbursement. The clockwise air circulation around the low pressure system at the South Pole forces air upwards, hypothetically sending ash upwards towards the Stratospheric jet streams, and thus quickly dispersing it throughout the globe.
#### Melting ice {#melting_ice}
Recently, in 2017, a study found evidence of subglacial volcanic activity within the West Antarctic Ice Sheet. This activity poses a threat to the stability of the Ice Sheet, as volcanic activity leads to increased melting. This could possibly plunge the West Antarctic Ice Sheet into a positive feedback loop of rising temperatures and increased melting.
## Canyons
There are three vast canyons that run for hundreds of kilometers, cutting through tall mountains. None of the canyons are visible at the snow-covered surface of the continent since they are buried under hundreds of meters of ice. The largest of the canyons is called Foundation Trough and is over 350 km long and 35 km wide. The Patuxent Trough is more than 300 km long and over 15 km wide, while the Offset Rift Basin is 150 km long and 30 km wide. These three troughs all lie under and cross the so-called \"ice divide\" -- the high ice ridge that runs all the way from the South Pole out towards the coast of West Antarctica.
## West Antarctica {#west_antarctica}
West Antarctica is the smaller part of the continent, (50° -- 180°W), divided into:
### Areas
- Antarctic Peninsula (55° -- 75°W)
- Graham Land
- Palmer Land
- Queen Elizabeth Land (20°W -- 80°W)
- Ellsworth Land (79°45\' -- 103°24\'W)
- English Coast
- Bryan Coast
- Eights Coast
- Marie Byrd Land (103°24\' -- 158°W)
- Walgreen Coast
- Bakutis Coast
- Hobbs Coast
- Ruppert Coast
- Saunders Coast
- King Edward VII Land (166°E -- 155°W)
- Shirase Coast
### Seas
- Scotia Sea (26°30\' -- 65°W)
- Weddell Sea (57°18\' -- 102°20\'W)
- Bellingshausen Sea (57°18\' -- 102°20\'W)
- Amundsen Sea (102°20′ -- 126°W)
### Ice shelves {#ice_shelves}
Larger ice shelves are:
- Filchner-Ronne Ice Shelf (30° -- 83°W)
- Larsen Ice Shelf
- Abbot Ice Shelf (89°35\' -- 103°W)
- Getz Ice Shelf (114°30\' -- 136°W)
- Sulzberger Ice Shelf
- Ross Ice Shelf (166°E -- 155°W)
For all ice shelves see List of Antarctic ice shelves.
### Islands
For a list of all Antarctic islands see List of Antarctic and sub-Antarctic islands.
## East Antarctica {#east_antarctica}
East Antarctica is the larger part of the continent, (50°W -- 180°E), both the South Magnetic Pole and geographic South Pole are situated here. Divided into:
### Areas {#areas_1}
- Coats Land (20° -- 36°W)
- Queen Maud Land (20°W -- 45°E)
- Princess Martha Coast
- Princess Astrid Coast
- Princess Ragnhild Coast
- Prince Harald Coast
- Prince Olav Coast
- Enderby Land (44°38\' -- 56°25\'E)
- Kemp Land (56°25\' -- 59°34\'E)
- Mac. Robertson Land (59°34\' -- 73°E)
- Princess Elizabeth Land (73° -- 87°43\'E)
- Wilhelm II Land (87°43\' -- 91°54\'E)
- Queen Mary Land (91°54\' -- 100°30\'E)
- Wilkes Land (100°31\' -- 136°11\'E)
- Adélie Land (136°11′ -- 142°02′E)
- George V Land (142°02\' -- 153°45\'E)
- George V Coast
- Zélée Subglacial Trench
- Oates Land (153°45\' -- 160°E)
- Victoria Land (70°30\' -- 78°\'S)
### Seas {#seas_1}
- Weddell Sea (57°18\' -- 102°20\'W)
- King Haakon VII Sea (20°W -- 45°E)
- Davis Sea (82° -- 96°E)
- Mawson Sea (95°45\' -- 113°E)
- D\'Urville Sea (140°E)
- Ross Sea (166°E -- 155°W)
- Bellingshausen Sea (57°18\' -- 102°20\'W)
- Scotia Sea (26°30\' -- 65°W)
### Ice shelves {#ice_shelves_1}
Larger ice shelves are:
- Riiser-Larsen Ice Shelf
- Ekstrom Ice Shelf
- Amery Ice Shelf
- West Ice Shelf
- Shackleton Ice Shelf
- Voyeykov Ice Shelf
For all ice shelves see List of Antarctic ice shelves.
### Islands {#islands_1}
For a list of all Antarctic islands see List of Antarctic and sub-Antarctic islands.
## Research stations {#research_stations}
## Territorial landclaims {#territorial_landclaims}
Seven nations have made official Territorial claims in Antarctica.
## Dependences and territories {#dependences_and_territories}
- Bouvet Island
- French Southern and Antarctic Lands
- Heard and McDonald Islands
- South Georgia and the South Sandwich Islands
- Peter I Island
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Transport in Antarctica
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**Transport in Antarctica** has transformed from explorers crossing the isolated remote area of Antarctica by foot to a more open era due to human technologies enabling more convenient and faster transport, predominantly by air and water, but also by land as well. Transportation technologies on a remote area like Antarctica need to be able to deal with extremely low temperatures and continuous winds to ensure the travelers\' safety. Due to the fragility of the Antarctic environment, only a limited amount of transport movements can take place and sustainable transportation technologies have to be used to reduce the ecological footprint. The infrastructure of land, water and air transport needs to be safe and sustainable. Currently thousands of tourists and hundreds of scientists a year depend on the Antarctic transportation system.
Important parts of Antarctic transport include ships, but unlike warmer areas access may also require an icebreaker ship. Aircraft and airports are important but have some unique aspects; airstrips may be built on ice or compacted snow and aircraft with ski may be used. On the ground, transport includes traditionally wheeled vehicles adapted to the cold, but also vehicles with skis, such as snowmobiles are important as are towed sleds.
## Land transport {#land_transport}
### Roads and traverses {#roads_and_traverses}
Winds continuously blow snow on roads in Antarctica.
The South Pole Traverse (McMurdo--South Pole highway) is approximately 1450 km long and links the United States McMurdo Station on the coast to the Amundsen--Scott South Pole Station. It was constructed by leveling snow and in crevasses, but is not paved. There are flags to mark the road.
Also, the United States Antarctic Program maintains two ice roads during the austral summer. One provides access to Pegasus Field on the Ross Ice Shelf. The ice road between Pegasus Field and McMurdo Station is about 14 mi. The other road provides access to the Ice Runway, which is on sea ice. The road between the Ice Runway and McMurdo Station varies in length from year to year depending on many factors, including ice stability. These roads are critical for resupplying McMurdo Station, Scott Base, and Amundsen--Scott South Pole Station.
### Vehicles
The scarcity and poor quality of road infrastructure limits land transportation by conventional vehicles.
A normal car on tires has very limited capability in Antarctic conditions. Scientific bases are often built on snow-free areas (oases) close to the ocean. Around these stations and on a hard packed snow or ice, tire based vehicles can drive but on deeper and softer snow, a normal tire-based vehicle cannot travel. Due to these limitations, vehicles on belts have been the preferred option in Antarctica. In 1997, two specialized cars with very large tires running tire pressure as low as 1.5 psi travelled onto the high Antarctica Plateau, giving strong indication that tire based vehicles could be an option for efficient travelling in Antarctica. Mawson Station used classic Volkswagen Beetles, the first production cars to be utilized in Antarctica, from 1963 to 1970. The first of these was named the *Antarctica 1*.
In December 1997 into February 1998 two AT44, 4x4 cars (built in Iceland by Arctic Trucks with tire size of 44-inch tall) joined an expedition by the Swedish Polar Institution (SWEA). The cars got used to transport people and supplies from the Ice shelf to WASA station, to perform scanning of the snow and support a drilling expedition to on the Antarctica Plateau 76°S 8°03\'W. This is the first time tire based vehicles successfully travel on the Antarctica high plateau. In 2005, a team of six people took part in the Ice Challenger Expedition. Travelling in a specially designed six wheel drive vehicle, the team completed the journey from the Antarctic coast at Patriot Hills to the geographic South Pole in 69 hours. In doing so they easily beat the previous record of 24 days. They arrived at the South Pole on December 12, 2005. The team members on that expedition were Andrew Regan, Jason De Carteret, Andrew Moon, Richard Griffiths, Gunnar Egilsson and Andrew Miles. The expedition successfully showed that wheeled transport on the continent is not only possible but also often more practical. The expedition also hoped to raise awareness about global warming and climate change.
From start of December 2008 into February 2009, four AT44, 4x4 cars were used to support a ski race by Amundsen Omega 3, from S82° 41\' E17° 43\' to South Pole. A film was made of this race by BBC called \"On Thin Ice\" with Ben Fogle and James Cracknell. The cars started from Novo airbase at S70° 49\' E11° 38\', establish a route onto the plateau through the crevasse areas in the Shcherbakov Mountain Range driving nearly 1500 km to the start line of the ski race. For the return journey each car covered between 5400 and with one fuel depot on the way.
From 2008 to date (Dec 2015) tire based cars, AT44 4x4 and AT44 6x6 have been used every season to support various NGO and scientific expedition/projects, supporting flights, fuel drops, filming, skiers, biker, a tractor, collecting snow samples and more. The combined distance covered on the Antarctica Plateau is over 220,000 km and even though towing capacity is much lower than for most belt based vehicles, the tire based cars multiply the travel speed and use only a fraction of the fuel making this an option for some expeditions/projects.
A second expedition led by Andrew Regan and Andrew Moon departed in November 2010. The Moon-Regan Trans Antarctic Expedition this time traversed the entire continent twice, using two six-wheel-drive vehicles and a Concept Ice Vehicle designed by Lotus. This time the team used the expedition to raise awareness about the global environmental importance of the Antarctic region and to show that biofuel can be a viable and environmentally friendly option.
## Water transport {#water_transport}
Antarctica\'s only harbour is at McMurdo Station. Most coastal stations have offshore anchorages, and supplies are transferred from ship to shore by small boats, barges, and helicopters. A few stations have a basic wharf facility. All ships at port are subject to inspection in accordance with Article 7, Antarctic Treaty. Offshore anchorage is sparse and intermittent, but poses no problem to sailboats designed for the ice, typically with lifting keels and long shorelines. McMurdo Station (77 51 S 166 40 E), Palmer Station (64 43 S 64 03 W); government use only except by permit (see Permit Office under \"Legal System\"). A number of tour boats, ranging from large motorized vessels to small sailing yachts, visit the Antarctic Peninsula during the summer months (January--March). Most are based in Ushuaia, Argentina.
## Air transport {#air_transport}
Transport in Antarctica takes place by air, using fixed-wing aircraft and helicopters. Runways and helicopter pads have to be kept snow-free to ensure safe take off and landing conditions.
Antarctica has 20 airports, but there are no developed public-access airports or landing facilities. Thirty stations, operated by 16 national governments party to the Antarctic Treaty, have landing facilities for either helicopters and/or fixed-wing aircraft; commercial enterprises operate two additional air facilities. Helicopter pads are available at 27 stations; runways at 15 locations are gravel, sea-ice, blue-ice, or compacted snow suitable for landing wheeled, fixed-wing aircraft; of these, one is greater than 3 km in length, six are between 2 and in length, three are between 1 and in length, three are less than 1 km in length, and two are of unknown length; snow surface skiways, limited to use by ski-equipped, fixed-wing aircraft, are available at another 15 locations; of these, four are greater than 3 km in length, three are between 2 km and 3 km in length, two are between 1 km and 2 km in length, two are less than 1 km in length, and data is unavailable for the remaining four.
Antarctic airports are subject to severe restrictions and limitations resulting from extreme seasonal and geographic conditions; they do not meet ICAO standards, and advance approval from the respective governmental or nongovernmental operating organization is required for landing (1999 est.) Flights to the continent in the permanent darkness of the winter are normally only undertaken in an emergency, with burning barrels of fuel to outline a runway. On September 11, 2008, a United States Air Force C-17 Globemaster III successfully completed the first landing in Antarctica using night-vision goggles at Pegasus Field.
In April 2001 an emergency evacuation of Dr. Ronald Shemenski was needed from Amundsen--Scott South Pole Station when he contracted pancreatitis. Three C-130 Hercules were called back before their final leg because of weather. Organizers then called on Kenn Borek Air based in Calgary, Alberta. Two de Havilland Twin Otters were dispatched out of Calgary with one being back-up. Twin Otters are specifically designed for the Canadian north and Kenn Borek Air\'s motto is \"Anywhere, Anytime, World-Wide\". The mission was a success but not without difficulties and drawbacks. Ground crews needed to create a 2 km runway with tracked equipment not designed to operate in the low temperatures at that time of year, the aircraft controls had to be \"jerry-rigged\" when the flaps were frozen in position after landing, and instruments were not reliable because of the cold. When they saw a \"faint pink line on the horizon\" they knew they were going in the right direction. This was the first rescue from the South Pole during winter. Canada honoured the Otter crew for bravery.
In 2021, an Airbus A340 aeroplane operated by Portuguese charter airline Hi Fly landed in Antarctica for the first time.
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Geography of Alabama
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The **geography of Alabama** describes a state in the Southeastern United States in North America. It extends from high mountains to low valleys and sandy beaches. Alabama is 30th in size and borders four U.S. states: Mississippi, Tennessee, Georgia, and Florida. It also borders the Gulf of Mexico.
## Physical features {#physical_features}
Extending entirely across the state of Alabama for about 20 mi northern boundary, and in the middle stretching 60 mi farther north, is the Cumberland Plateau, or Tennessee Valley region, broken into broad tablelands by the dissection of rivers. In the northern part of this plateau, west of Jackson county, there are about 1000 sqmi of level highlands from 700 to above sea level. South of these highlands, occupying a narrow strip on each side of the Tennessee River, is a country of gentle rolling lowlands varying in elevation from 500 to. To the northeast of these highlands and lowlands is a rugged section with steep mountain-sides, deep narrow coves and valleys, and flat mountain-tops. Its elevations range from 400 to. In the remainder of this region, the southern portion, the most prominent feature is *Little Mountain*, extending about 80 mi from east to west between two valleys, and rising precipitously on the north side 500 ft above them or 1000 ft above the sea.
Adjoining the Cumberland Plateau region on the southeast is the Appalachian Valley (locally known as Coosa Valley) region, which is the southern extremity of the Appalachian Mountains, and occupies an area within the state of about 8000 sqmi. This is a limestone belt with parallel hard rock ridges left standing by erosion to form mountains. Although the general direction of the mountains, ridges, and valleys is northeast and southwest, irregularity is one of the most prominent characteristics. In the northeast are several flat-topped mountains, of which Raccoon and Lookout are the most prominent, having a maximum elevation near the Georgia line of little more than 1800 ft and gradually decreasing in height toward the southwest, where Sand Mountain is a continuation of Raccoon. South of these the mountains are marked by steep northwest sides, sharp crests and gently sloping southeast sides.
Southeast of the Appalachian Valley region, the Piedmont Plateau also crosses the Alabama border from the N.E. and occupies a small triangular-shaped section of which Randolph and Clay counties, together with the northern part of Tallapoosa and Chambers, form the principal portion. Its surface is gently undulating and has an elevation of about 1000 ft above sea level. The Piedmont Plateau is a lowland worn down by erosion on hard crystalline rocks, then uplifted to form a plateau.
The remainder of the state is occupied by the *Coastal Plain*. This is crossed by foothills and rolling prairies in the central part of the state, where it has a mean elevation of about 600 ft, becomes lower and more level toward the southwest, and in the extreme south is flat and but slightly elevated above the sea. The Cumberland Plateau region is drained to the west-northwest by the Tennessee River and its tributaries; all other parts of the state are drained to the southwest. In the Appalachian Valley region the Coosa River is the principal river; and in the Piedmont Plateau, the Tallapoosa River. In the Coastal Plain are the Tombigbee River in the west, the Alabama River (formed by the Coosa and Tallapoosa) in the western central, and in the east the Chattahoochee River, which forms almost half of the Georgia boundary. The Tombigbee and Alabama rivers unite near the southwest corner of the state, their waters discharging into Mobile Bay by the Mobile and Tensas rivers. The Black Warrior River is a considerable stream which joins the Tombigbee from the east.
The valleys in the north and northeast are usually deep and narrow, but in the Coastal Plain they are broad and in most cases rise in three successive terraces above the stream. The harbour of Mobile was formed by the drowning of the lower part of the valley of the Alabama and Tombigbee rivers as a result of the sinking of the land here, such sinking having occurred on other parts of the Gulf coast.
## Flora and fauna {#flora_and_fauna}
The fauna and flora of Alabama are similar to those of the Gulf states in general and have no distinctive characteristics. However, the Mobile River system has a high incidence of endemism among freshwater mollusks and biodiversity is high.
In Alabama, vast forests of pine constitute the largest proportion of the state\'s forest growth. There is also an abundance of cypress, hickory, oak, populus, and eastern redcedar trees. In other areas, hemlock growths in the north and southern white cedar in the southwest. Other native trees include ash, hackberry, and holly. In the Gulf region of the state grow various species of palmetto and palm. In Alabama there are more than 150 shrubs, including mountain laurel and rhododendron. Among cultivated plants are wisteria and camellia.
While in the past the state enjoyed a variety of mammals such as plains bison, eastern elk, North American cougar, bear, and deer, only the white-tailed deer remains abundant. Still fairly common are the bobcat, American beaver, muskrat, raccoon, Virginia opossum, rabbit, squirrel, red and gray foxes, and long-tailed weasel. Coypu and nine-banded armadillo have been introduced to the state and now also common.
Alabama\'s birds include golden and bald eagles, osprey and other hawks, yellow-shafted flickers, and black-and-white warblers. Game birds include bobwhite quail, duck, wild turkey, and goose. Freshwater fish such as bream, shad, bass, and sucker are common. Along the Gulf Coast there are seasonal runs of tarpon, pompano, red drum, and bonito.
The U.S. Fish and Wildlife Service lists as endangered 99 animals, fish, and birds, and 18 plant species. The endangered animals include the Alabama beach mouse, gray bat, Alabama red-bellied turtle, fin and humpback whales, bald eagle, and wood stork.
American black bear, racking horse, yellow-shafted flicker, wild turkey, Atlantic tarpon, largemouth bass, southern longleaf pine, eastern tiger swallowtail, monarch butterfly, Alabama red-bellied turtle, Red Hills salamander, camellia, oak-leaf hydrangea, peach, pecan, and blackberry are Alabama\'s state symbols.
## Climate and soil {#climate_and_soil}
The climate of Alabama is humid subtropical.
The heat of summer is tempered in the south by the winds from the Gulf of Mexico, and in the north by the elevation above the sea. The average annual temperature is highest in the southwest along the coast, and lowest in the northeast among the highlands. Thus at Mobile the annual mean is 67 °F, the mean for the summer 81 °F, and for the winter 52 °F; and at Valley Head, in De Kalb county, the annual mean is 59 °F, the mean for the summer 75 °F, and for the winter 41 °F. At Montgomery, in the central region, the average annual temperature is 66 °F, with a winter average of 49 °F, and a summer average of 81 °F. The average winter minimum for the entire state is 35 °F, and there is an average of 35 days in each year in which the thermometer falls below the freezing-point. At extremely rare intervals the thermometer has fallen below zero (-18 °C), as was the case in the remarkable cold wave of the 12th-13 February 1899, when an absolute minimum of -17 °F was registered at Valley Head. The highest temperature ever recorded was 109 °F in Talladega county in 1902.
The amount of precipitation is greatest along the coast (62 inches/1,574 mm) and evenly distributed through the rest of the state (about 52 inches/1,320 mm). During each winter there is usually one fall of snow in the south and two in the north; but the snow quickly disappears, and sometimes, during an entire winter, the ground is not covered with snow. Heavy snowfall can occur, such as during the New Year\'s Eve 1963 snowstorm and the 1993 Storm of the Century. Hailstorms occur occasionally in the spring and summer, but are seldom destructive. Heavy fogs are rare, and are confined chiefly to the coast. Thunderstorms occur throughout the year - they are most common in the summer, but most severe in the spring and fall, when destructive winds and tornadoes occasionally occur. The prevailing winds are from the news. Hurricanes are quite common in the state, especially in the southern part, and major hurricanes occasionally strike the coast which can be very destructive.
As regards its soil, Alabama may be divided into four regions. Extending from the Gulf northward for about 150 mi is the outer belt of the Coastal Plain, also called the *Timber Belt,* whose soil is sandy and poor, but responds well to fertilization. North of this is the inner lowland of the Coastal Plain, or the *Black Prairie,* which includes some 13000 sqmi and seventeen counties. It receives its name from its soil (weathered from the weak underlying limestone), which is black in colour, almost destitute of sand and loam, and rich in limestone and marl formations, especially adapted to the production of cotton; hence the region is also called the *Cotton Belt.* Between the *Cotton Belt* and the Tennessee Valley is the mineral region, the *Old Land* area---a region of resistant rocks---whose soils, also derived from weathering in silu, are of varied fertility, the best coming from the granites, sandstones and limestones, the poorest from the gneisses, schists and slates. North of the mineral region is the *Cereal Belt,* embracing the Tennessee Valley and the counties beyond, whose richest soils are the red clays and dark loams of the river valley; north of which are less fertile soils, produced by siliceous and sandstone formations.
## Wetumpka Meteor Crater {#wetumpka_meteor_crater}
Wetumpka is the home of \"Alabama\'s greatest natural disaster.\" A 1000 ft-wide meteorite hit the area about 80 million years ago. The hills just east of downtown showcase the eroded remains of the 5 mi wide impact crater that was blasted into the bedrock, with the area labeled the Wetumpka crater or astrobleme (\"star-wound\") for the concentric rings of fractures and zones of shattered rock can be found beneath the surface. In 2002, Christian Koeberl with the Institute of Geochemistry University of Vienna published evidence and established the site as an internationally recognized impact crater.
## Public lands {#public_lands}
Alabama includes several types of public use lands. These include four national forests and one national preserve within state borders that provide over 25% of the state\'s public recreation land.
- land regions
- Alabama State Parks
- Alabama Public Fishing Lakes
- Alabama Wildlife Management Areas
- Little River Canyon National Preserve
- Russell Cave National Monument
- National Forests
- Conecuh National Forest
- Talladega National Forest
- Tuskegee National Forest
- William B. Bankhead National Forest
- Wilderness Areas
- Cheaha Wilderness
- Dugger Mountain Wilderness
- Sipsey Wilderness
- National Recreation Trail
- Pinhoti National Recreation Trail
- National Wildlife Refuge
- Bon Secour National Wildlife Refuge
- Cahaba River National Wildlife Refuge
- Choctaw National Wildlife Refuge
- Eufaula National Wildlife Refuge
- Fern Cave National Wildlife Refuge
- Key Cave National Wildlife Refuge
- Mountain Longleaf National Wildlife Refuge
- Sauta Cave National Wildlife Refuge
- Watercress Darter National Wildlife Refuge
- Wheeler National Wildlife Refuge
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Alfred Lawson
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**Alfred William Lawson** (March 24, 1869 -- November 29, 1954) was an English-born professional baseball player, aviator, and utopian philosopher. He played baseball, managed and promoted leagues from 1887 through 1916, and pioneered the U.S. aircraft industry. He also published two early aviation trade journals.
Lawson is frequently cited as the inventor of the airliner and received several of the first air mail contracts, which he ultimately did not fulfill. He founded the Lawson Aircraft Company in Green Bay, Wisconsin, to build military training aircraft and later the Lawson Airplane Company in South Milwaukee, Wisconsin, to build airliners.
The crash of his ambitious Lawson L-4 \"Midnight Liner\" during its trial flight takeoff on May 8, 1921, ended his best chance for commercial aviation success.
In 1904, he wrote a utopian novel, *Born Again*, in which he developed the philosophy which later became Lawsonomy.
## Baseball career (1888--1907) {#baseball_career_18881907}
Lawson made one start for the Boston Beaneaters and two for the Pittsburgh Alleghenys during the 1890 season. His minor league playing career lasted through 1895. Lawson later managed in the minors from 1905 to 1907.
### Union Professional League {#union_professional_league}
In 1908, Lawson started a new professional baseball league called the Union Professional League. The league took the field in April but folded one month later because of financial difficulties.
## Aviation career (1908--1928) {#aviation_career_19081928}
An early aviation advocate, in October 1908, Lawson started the magazine *Fly* to stimulate public interest and educate readers on the new aviation science fundamentals. It sold for 10 cents a copy from newsstands across the country. In 1910, moving to New York City, he renamed the magazine *Aircraft* and published it until 1914. The magazine chronicled the technical developments of the early aviation pioneers.
Lawson was the first advocate for commercial air travel, coining the term \"airline.\" He also advocated for a strong American flying force, lobbying Congress in 1913 to expand its appropriations for Army aircraft.
In early 1913, Lawson learned to fly the Sloan-Deperdussin and the Moisant-Bleriot monoplanes, becoming an accomplished pilot. Later that year, he bought a Thomas flying boat and became the first air commuter to regularly fly from his country house in Seidler\'s Beach, New Jersey, to the foot of 75th Street in New York City (about 35 miles).
In 1917, utilizing the knowledge gained from ten years of advocating aviation, he built his first airplane, the Lawson Military Tractor 1 (MT-1) trainer, and founded the Lawson Aircraft Corporation. The company\'s plant was in Green Bay, Wisconsin. There, Lawson secured a contract and built the Lawson MT-2. He also designed the steel fuselage Lawson Armored Battler, which never got beyond the drafting board, given doubts within the Army aviation community and the signing of the armistice.
After the war, in 1919, Lawson started a project to build America\'s first airline. He secured financial backing, and in five months, he had built and demonstrated in flight his biplane airliner, the 18-passenger Lawson L-2. He demonstrated its capabilities in a 2000-mile multi-city tour from Milwaukee to Chicago-Toledo-Cleveland-Buffalo-Syracuse-New York City-Washington, D.C.-Collinsville-Dayton-Chicago and back to Milwaukee, creating a buzz of positive press.
The publicity allowed Lawson to secure an additional \$1 million to build the 26-passenger Midnight Liner. The aircraft crashed on takeoff on its maiden flight.
In late 1920, he secured government contracts for three airmail routes and to deliver ten warplanes. However, because of the fall 1920 recession, he could not secure the necessary \$100,000 in cash reserves and had to decline the contracts.
In 1926, he started his last airliner, the 56-seat, two-tier Lawson super airliner.
In this phase of his life, he was considered one of the leading thinkers in the budding American commercial aviation community; however, his inability to secure financial backing for his ideas led him to turn to economics, philosophy, and organization.
## Lawsonomy (1929--1954) {#lawsonomy_19291954}
In the 1920s, Lawson promoted health practices, including vegetarianism, and claimed to have found the secret of living to 200. He also developed his own highly unusual theories of physics, according to which such concepts as \"penetrability\", \"suction and pressure\" and \"zig-zag-and-swirl\" were discoveries on par with Einstein\'s theory of relativity. He published numerous books on these concepts, all set in a distinctive typography.
He later propounded a philosophy, Lawsonomy, and the Lawsonian religion. He also developed, during the Great Depression, the populist economic theory of \"Direct Credits\", according to which banks are the cause of all economic woes, the oppressors of both capital and labor. Lawson believed that the government should replace banks as the provider of loans to business and workers. He predicted the worldwide adoption of Lawsonian principles once \"everybody understands this subject\". His rallies and lectures attracted thousands of listeners in the early 1930s, mainly in the upper Midwest, but by the late 1930s the crowds had dwindled.
His claims about his greatness became increasingly hyperbolic. The *Lawsonomy trilogy*, which Lawson considered his intellectual masterpiece, is replete with such self-referential statements as \"About every two thousand years a new teacher with advanced intellectual equipment appears upon earth to lead the people a step or two nearer the one God of everybody\".
In 1943, he founded the Humanity Benefactor Foundation and University of Lawsonomy in Des Moines, on the site of Des Moines University, to spread his teachings and offer the degree of \"Knowledgian\", but after various IRS and other investigations it was closed and finally sold in 1954, the year of Lawson\'s death. His financial arrangements remain mysterious to this day, and in later years, he seems to have owned little property, moving from city to city as a guest of his far-flung acolytes. In 1952, he testified before a United States Senate investigative committee on allegations that his organization had bought war surplus machines and then sold them for a profit despite claiming non-profit status. His attempt to explain Lawsonomy to the senators ended in mutual frustration and bafflement.
A farm near Racine, Wisconsin, is the only remaining university facility, although a tiny handful of churches may yet survive in places such as Wichita, Kansas. The large sign, formerly reading \"University of Lawsonomy\", was a familiar landmark for motorists in the region for many years and was visible from Interstate 94 about 13 mi north of the Illinois state line, on the east side of the highway. A storm in the spring of 2009 destroyed the sign, although the supporting posts are still visible. On the northbound side of Interstate 94, a sign on the roof of the building nearest the freeway said \"Study Natural Law\" until being shingled over in October 2014.
In 2018, the Town of Mount Pleasant paid \$933,000 to purchase the property on the northbound side of Interstate 94 for the Foxconn project. All remaining buildings were demolished and removed. Lawsonomy maintains a small following to this day.
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Abbess
|
An **abbess** (Latin: *abbatissa*) is the female superior of a community of nuns in an abbey.
## Description
In the Catholic Church (both the Latin Church and Eastern Catholic), Eastern Orthodox, Coptic, Lutheran and Anglican abbeys, the mode of election, position, rights, and authority of an abbess correspond generally with those of an abbot. She must be at least 40 years old and have been a nun for 10 years. The age requirement in the Catholic Church has evolved over time, ranging from 30 to 60. The requirement of 10 years as a nun is only eight in Catholicism. In the rare case of there not being a nun with the qualifications, the requirements may be lowered to 30 years of age and five of those in an \"upright manner\", as determined by the superior. A woman who is of illegitimate birth, is not a virgin, has undergone non-salutory public penance, is a widow, or is blind or deaf, is typically disqualified for the position, saving by permission of the Holy See. The office is elective, the choice being by the secret votes of the nuns belonging to the community. Like an abbot, after being confirmed in her office by the Holy See, an abbess is solemnly admitted to her office by a formal blessing, conferred by the bishop in whose territory the monastery is located, or by an abbot or another bishop with appropriate permission. Unlike the abbot, the abbess receives only the ring, the crosier, and a copy of the rule of the order. She does not receive a mitre as part of the ceremony. The abbess also traditionally adds a pectoral cross to the outside of her habit as a symbol of office, though she continues to wear a modified form of her religious habit or dress, as she is unordained---females cannot be ordained---and so does not vest or use choir dress in the liturgy.`{{Failed verification|date=February 2024|reason=Source doesn't mention vestments or dress.}}`{=mediawiki} An abbess serves for life, except in Italy and some adjacent islands.
### Roles and responsibilities {#roles_and_responsibilities}
Abbesses are, like abbots, major superiors according to canon law, the equivalents of abbots or bishops (the ordained male members of the church hierarchy who have, by right of their own office, executive jurisdiction over a building, diocesan territory, or a communal or non-communal group of persons---juridical entities under church law). They receive the vows of the nuns of the abbey; they may admit candidates to their order\'s novitiate; they may send them to study; and they may send them to do pastoral or missionary, or to work or assist---to the extent allowed by canon and civil law---in the administration and ministry of a parish or diocese (these activities could be inside or outside the community\'s territory). They have full authority in its administration.
However, there are significant limitations.
- They may not administer the sacraments, whose celebration is reserved to bishops, priests, deacons (clerics), namely, those in Holy Orders.
- They may make provision for an ordained cleric to help train and to admit some of their members, if needed, as altar servers, extraordinary ministers of Holy Communion, or lectors---all ministries which are now open to the unordained.
- They may not serve as a witness to a marriage except by special rescript.
- They may not administer Penance (Reconciliation), Anointing of the Sick (Extreme Unction), or function as an ordained celebrant or concelebrant of the Mass (by virtue of their office and their training and institution, they may act, if the need arises, as altar servers, lectors, ushers, porters, or extraordinary ministers of Holy Communion, and if need be, the Host).
- They may preside over the Liturgy of the Hours which they are obliged to say with their community, speak on Scripture to their community, and give certain types of blessings not reserved to the clergy. On the other hand, they may not ordinarily preach a sermon or homily, nor read the Gospel during Mass.
- As they do not receive episcopal ordination in the Catholic, Orthodox and Oriental Churches, they do not possess the ability to ordain others, nor do they exercise the authority they do possess under canon law over any territories outside of their monastery and its territory (though non-cloistered, non-contemplative female religious members who are based in a convent or monastery but who participate in external affairs may assist as needed by the diocesan bishop and local secular clergy and laity, in certain pastoral ministries and administrative and non-administrative functions not requiring ordained ministry or status as a male cleric in those churches or programs).
There are exigent circumstances, where due to Apostolical privilege, certain Abbesses have been granted rights and responsibilities above the normal, such as the Abbess of the Cistercian Monastery of the Abbey of Santa María la Real de Las Huelgas near Burgos, Spain. Also granted exceptional rights was the Abbess of the Cistercian order in Conversano Italy. She was granted the ability to appoint her own vicar-general, select and approve the confessors, along with the practice of receiving the public homage of her clergy. This practice continued until some of the duties were modified due to an appeal by the clergy to Rome. Finally in 1750, the public homage was abolished.
During the Middle Ages (7th--10th centuries) in the Catholic Church, greater restrictions on abbesses\' spiritual independence gained pace. Instruments of church authority, from papal bulls down to local sanctions, were increasingly used to restrict their freedom to dispense blessings, administer sacraments, including the veiling of nuns, and publicly read the gospels or preach. Such spiritual---and even temporal---authority had in earlier church history, largely been unremarkable. As Thomas Oestereich, contributor to the *Catholic Encyclopedia* (1913), makes clear, abbesses\' past spiritual authority was increasingly seen as the \"usurpation\" of corresponding priestly power, and a solely male privilege. He gives an example of the attitude toward such practice, from the 9th century, which persists in church administrative control into the modern era:
Similarly, in 1210, Innocent III (died 1216) expressed his view of the Cistercian Abbesses of Burgos and Palencia in Spain, who preached and heard confessions of their own religious, characterizing these acts as \"unheard of, most indecorous, and highly preposterous.\"
## History
Historically, in some Celtic monasteries, abbesses presided over joint-houses of monks and nuns, the most famous example being Saint Brigid of Kildare\'s leadership in the founding of the monastery at Kildare in Ireland. This custom accompanied Celtic monastic missions to France, Spain, and even to Rome itself. In 1115, Robert, the founder of Fontevraud Abbey near Chinon and Saumur, France, committed the government of the whole order, men as well as women, to a female superior.
In Lutheran churches, the title of abbess (*Äbtissin*) has in some cases survived (for example, in the Itzehoe Convent to designate the heads of abbeys which since the Protestant Reformation have continued as monasteries or convents (*\[\[Stift\]\]e*). These positions continued, merely changing from Catholic to Lutheran. The first to make this change was the Abbey of Quedlinburg, whose last Catholic Abbess died in 1514. These are collegiate foundations, which provide a home and an income for unmarried ladies, generally of noble birth, called canonesses (*Kanonissinen*), or more usually, *Stiftsdamen* or *Kapitularinnen*. The office of abbess is of considerable social dignity, and in the past, was sometimes filled by princesses of the reigning houses. Until the dissolution of Holy Roman Empire and mediatisation of smaller imperial fiefs by Napoleon, the evangelical Abbess of Quedlinburg was also per officio the head of that *\[\[reichsunmittelbar\]\]* state. The last such ruling abbess was Sofia Albertina, Princess of Sweden. The abess Hildegard of Fraunmünster Abbey sat in the Imperial Diet among other princes of the Holy Roman Empire. The oldest women\'s abbey in Germany is St. Marienthal Abbey of Cistercian nuns, near Ostritz, established during the early 13th century.
In the Hradčany of Prague is a Catholic institute whose mistress is titled an Abbess. It was founded in 1755 by the Empress Maria Theresa, and traditionally was responsible for the coronation of the Queen of Bohemia. The Abbess is required to be an Austrian Archduchess.
it was estimated the Catholic Church had around 200 presiding abbesses.
## Abbas placename {#abbas_placename}
The word \'Abbas\' is used as part of a place name (for example, the English villages of Compton Abbas and Milton Abbas). The name usually relates to land previously owned by an abbess.
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Abdominal surgery
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The term **abdominal surgery** broadly covers surgical procedures that involve opening the abdomen (laparotomy). Surgery of each abdominal organ is dealt with separately in connection with the description of that organ (see stomach, kidney, liver, etc.) Diseases affecting the abdominal cavity are dealt with generally under their own names.
## Types
The most common abdominal surgeries are described below.
- Appendectomy: surgical opening of the abdominal cavity and removal of the appendix. Typically performed as definitive treatment for appendicitis, although sometimes the appendix is prophylactically removed incidental to another abdominal procedure.
- Caesarean section (also known as C-section): a surgical procedure in which one or more incisions are made through a mother\'s abdomen (laparotomy) and uterus (hysterotomy) to deliver one or more babies, or, rarely, to remove a dead fetus.
- Inguinal hernia surgery: the repair of an inguinal hernia.
- Exploratory laparotomy: the opening of the abdominal cavity for direct examination of its contents; for example, to locate a source of bleeding or trauma. It may or may not be followed by repair or removal of the primary problem.
- Laparoscopy: a minimally invasive approach to abdominal surgery where rigid tubes are inserted through small incisions into the abdominal cavity. The tubes allow introduction of a small camera, surgical instruments, and gases into the cavity for direct or indirect visualization and treatment of the abdomen. The abdomen is inflated with carbon dioxide gas to facilitate visualization and, often, a small video camera is used to show the procedure on a monitor in the operating room. The surgeon manipulates instruments within the abdominal cavity to perform procedures such as cholecystectomy (gallbladder removal), the most common laparoscopic procedure. The laparoscopic method speeds recovery time and reduces blood loss and infection as compared to the traditional \"open\" method.
## Complications
Complications of abdominal surgery include, but are not limited to:
- Adhesions (also called scar tissue): complications of postoperative adhesion formation are frequent, they have a large negative effect on patients' health, and increase workload in clinical practice
- Bleeding
- Infection
- Paralytic ileus: short-term paralysis of the bowel
- Perioperative mortality, any death occurring within 30 days after surgery
- Shock
Sterile technique, aseptic post-operative care, antibiotics, use of the WHO Surgical Safety Checklist, and vigilant post-operative monitoring greatly reduce the risk of these complications. Planned surgery performed under sterile conditions is much less risky than that performed under emergency or unsterile conditions. The contents of the bowel are unsterile, and thus leakage of bowel contents, as from trauma, substantially increases the risk of infection.
Globally, there are few studies comparing perioperative mortality following abdominal surgery across different health systems. One major prospective study of 10,745 adult patients undergoing emergency laparotomy from 357 centres in 58 high-, middle-, and low-income countries found that mortality is three times higher in low- compared with high-HDI countries even when adjusted for prognostic factors. In this study the overall global mortality rate was 1.6 percent at 24 hours (high 1.1 percent, middle 1.9 percent, low 3.4 percent), increasing to 5.4 percent by 30 days (high 4.5 percent, middle 6.0 percent, low 8.6 percent). Of the 578 patients who died, 404 (69.9 percent) did so between 24 hours and 30 days following surgery (high 74.2 percent, middle 68.8 percent, low 60.5 percent). Patient safety factors were suggested to play an important role, with use of the WHO Surgical Safety Checklist associated with reduced mortality at 30 days.
Taking a similar approach, a unique global study of 1,409 children undergoing emergency laparotomy from 253 centres in 43 countries showed that adjusted mortality in children following surgery may be as high as 7 times greater in low-HDI and middle-HDI countries compared with high-HDI countries, translating to 40 excess deaths per 1,000 procedures performed in these settings. Internationally, the most common operations performed were appendectomy, small bowel resection, pyloromyotomy and correction of intussusception. After adjustment for patient and hospital risk factors, child mortality at 30 days was significantly higher in low-HDI (adjusted OR 7.14 (95% CI 2.52 to 20.23)) and middle-HDI (4.42 (1.44 to 13.56)) countries compared with high-HDI countries.
Absorption of drugs administered orally was shown to be significantly affected following abdominal surgery.
There is low-certainty evidence that there is no difference between using scalpel and electrosurgery in infection rates during major abdominal surgeries.
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Abensberg
|
**Abensberg** (`{{IPA|de|ˈaːbənsˌbɛʁk|-|De-Abensberg.ogg}}`{=mediawiki}) is a town in the Lower Bavarian district of Kelheim, in Bavaria, Germany, lying around 30 km southwest of Regensburg, 40 km east of Ingolstadt, 50 km northwest of Landshut and 100 km north of Munich. It is situated on the river Abens, a tributary of the Danube.
## Geography
The town lies on the Abens river, a tributary of the Danube, around eight kilometres from the river\'s source. The area around Abensberg is characterized by the narrow valley of the Danube, where the Weltenburg Abbey stands, the valley of the Altmühl in the north, a left tributary of the Danube, and the famous Hallertau hops-planting region in the south. The town is divided into the municipalities of Abensberg, Arnhofen, Holzharlanden, Hörlbach, Offenstetten, Pullach and Sandharland.
### Divisions
Since the administrative reforms in Bavaria in the 1970s, the town also encompasses the following *Ortsteile*:
- In the town: Abensberg (main settlement), Aunkofen (civil parish), Badhaus (village)
- To the east: Gaden (village), See (village), Offenstetten (civil parish)
- To the north east: Arnhofen (civil parish), Baiern (village), Pullach (civil parish), Kleedorf (village)
- To the north: Sandharlanden (civil parish), Holzharlanden (civil parish), Buchhof (small hamlet)
- To the west: Schwaighausen (village), Schillhof (hamlet), Gilla (small hamlet)
- To the south: Aumühle (small hamlet), Allersdorf (hamlet)
- To the south east: Lehen (small hamlet), Mitterhörlbach (hamlet), Upper Hörlbach (village), Lower Hörlbach (hamlet)
## History
There had been settlement on this part of the Abens river since long before the High Middle Ages, dating back to Neolithic times. Of particular interest and national importance are the Neolithic flint mines at Arnhofen, where, around 7,000 years ago, Stone Age people made flint, which was fashioned into drills, blades and arrowheads, and was regarded as the steel of the Stone Age. Traces of over 20,000 individuals were found on this site. The modern history of Abensberg, which is often incorrectly compared with that of the third century Roman castra (military outpost) of Abusina, begins with Gebhard, who was the first to mention Abensberg as a town, in the middle of the 12th century. The earliest written reference to the town, under the name of *Habensperch*, came from this time, in around 1138. Gebhard was from the Babonen clan.
In 1256, the castrum of *Abensprech* was first mentioned, and on 12 June 1348, Margrave Ludwig of Brandenburg, and his brother, Duke Stephen of Bavaria, raised Abensberg to the status of a city, giving it the right to operate lower courts, enclose itself with a wall and hold markets. The wall was built by Count Ulrich III of Abensberg. Some of the thirty-two round towers and eight turrets are still preserved to this day.
In the Middle Ages, the people of Abensberg enjoyed a level of autonomy above their lord. They elected a city council, although only a small number of rich families were eligible for election.
In around 1390, the Carmelite Monastery of Our Lady of Abensberg was founded by Count John II and his wife, Agnes. Although Abensberg was an autonomous city, it remained dependent on the powerful Dukes of Bavaria. The last Lord of Abensberg, Niclas, Graf von Abensberg, supposedly named after his godfather, Nicholas of Kues, a Catholic cardinal, was murdered in 1485 by Christopher, a Duke of Bavaria-Munich. The year before, Niclas had unchivalrously taken Christopher captive as he bathed before a tournament in Munich. Although Christopher renounced his claim for revenge, he lay in wait for Niclas in Freising. When the latter arrived, he was killed by Seitz von Frauenberg. He is buried in the former convent of Abensberg.
Abensberg then lost its independence and became a part of the Duchy of Bavaria, and from then on was administered by a ducal official, the so-called caretaker. The castle of Abensberg was destroyed during the Thirty Years\' War, although the city had bought a guarantee of protection from the Swedish general, Carl Gustaf Wrangel. During the War of the Spanish Succession emperor Leopold I, who had occupied Bavaria, granted the fief of Abensberg to count Ernst von Abensperg und Traun (1608--1668) from an Austrian noble family named Traun that now received the name of the former counts of Abensberg (who were believed to be distant relatives). After the occupation ended, he was however dispossessed.
Johannes Aventinus (1477--1534) is the city\'s most famous son, the founder of the study of history in Bavaria. Aventinus, whose name was real name is Johann or Johannes Turmair (*Aventinus* being the Latin name of his birthplace) wrote the *Annals of Bavaria*, a valuable record of the early history of Germany and the first major written work on the subject. He is commemorated in the Walhalla temple, a monument near Regensburg to the distinguished figures of German history. Until 1800, Abensberg was a municipality belonging to the Straubing district of the Electorate of Bavaria. Abensberg also contained a magistrates\' court. In the Battle of Abensberg on 19--20 April 1809, Napoleon gained a significant victory over the Austrians under Archduke Ludwig of Austria and General Johann von Hiller.
### Coat of arms {#coat_of_arms}
The arms of the city are divided into two halves. On the left are the blue and white rhombuses of Bavaria, while the right half is split into two silver and black triangles. Two diagonally-crossed silver swords with golden handles rest on top.
The town has had a coat of arms since 1338, that of the Counts of Abensberg. With the death of the last Count, Nicholas of Abensberg, in 1485, the estates fell to the Duchy of Bavaria-Munich, meaning that henceforth only the Bavarian coat of arms was ever used.
On 31 December 1809, a decree of King Maximilian of Bavaria granted the city a new coat of arms, as a recognition of their (mainly humanitarian and logistic) services in the Battle of Abensberg the same year. The diagonally divided field in silver and black came from the old crest of the Counts of Abensberg, while the white and blue diamonds came from that of the House of Wittelsbach, the rulers of Bavaria. The swords recall the Battle of Abensberg.
The district of Offenstetten previously possessed its own coat of arms.
### Twinning
- Parga, Greece since 1986
- Lonigo, Italy since 1999
- Saint-Gilles, Gard, France since 2016
## Economy and Infrastructure {#economy_and_infrastructure}
The area around Abensberg, the so-called sand belt between Siegburg, Neustadt an der Donau, Abensberg and Langquaid, is used for the intensive farming of asparagus, due to the optimal soil condition and climate. 212 hectares of land can produce ninety-four asparagus plants. Abensberg asparagus enjoys a reputation among connoisseurs as a particular delicacy. In addition to asparagus, the production of hops plays a major role locally, the region having its own label, and there are still three independent breweries in the area. The town of Abensberg marks the start of the *Deutsche Hopfenstraße* (*German Hops Road*), a nickname given to the Bundesstraße 301, a German federal highway which runs through the heartland of Germany\'s hops-growing industry, ending in Freising.
### Transport
The Abensberg railway station is located on the Regensburg--Ingolstadt railway from Regensburg to Ingolstadt. The city can be reached via the A-93 Holledau-Regensburg road (exit Abensberg). Three Bundesstraße (German federal highways) cross south of Abensberg: B 16, B 299 and B 301.
## Public facilities {#public_facilities}
### Schools
Abensberg has two Grundschulen (primary school) and Mittelschule (open admission secondary school), and the Johann-Turmair-Realschule (secondary modern school). There is also a College of Agriculture and Home Economics. Since 2007, the Kelheim Berufsschule has had a campus in Abensberg, and outside the state sector is the St. Francis Vocational Training Centre, run by a Catholic youth organisation. In addition, there are two special schools, one near Abensberg, the other in the civil parish of Offenstetten.
## Culture and sightseeing {#culture_and_sightseeing}
### Theatre
In 2008, a former goods shed by the main railway station of Abensberg was converted into a theatre by local volunteers. The \"Theater am Bahnhof\" (*Theatre at the Railway Station*) is mostly used by the *Theatergruppe Lampenfieber* and was opened on 19 October 2008.
### Museums
Abensberg has a long tradition of museums. In the nineteenth century, Nicholas Stark und Peter Paul Dollinger began a collection based on local history. This collection and the collection of the *Heimatverein* (local history society) were united in 1963 into the Aventinus Museum, in the cloister of the former Carmelite monastery. On 7 July 2006, the new Town Museum of Abensberg was opened in the former duke\'s castle in the town.
### Kuchlbauer Brewery {#kuchlbauer_brewery}
Two blocks west of the Old Town is the Kuchlbauer Brewery and beer garden featuring the Kuchlbauer Tower, a colorful and unconventional observation tower designed by Viennese architect Friedensreich Hundertwasser. The brewery and tower are open to the public.
### Image gallery {#image_gallery}
<File:Abensberg> Stadtansicht.jpg\|View of the Old Town <File:Abensberg> Klosterkirche.jpg\|Carmelite Monastery <File:Abensberg> Stadtplatz.jpg\|Town Centre with Rathaus (town hall) <File:Abensberg> RegensburgerTor.jpg\|Regensburg Gate <File:SchlossAbensberg> LandkreisKelheim Niederbayern.JPG\|Site of the former castle <File:Herzogskasten> Abensberg.JPG\|Herzogskasten (Duke\'s storage house) <File:Abensberg> Kuchlbauerturm von Hundertwasser.JPG\|Kuchlbauer Tower
### Missing memorial {#missing_memorial}
Up until the 1950s, Abensberg and the surrounding villages contained a number of graves of victims of a Death March in the spring of 1945 from the Hersbruck sub-camp of the Dachau concentration camp, who were either murdered by the SS or died of exhaustion. They were originally buried where they died, but were later moved on the orders of the US military government to the cemeteries of their previous homes. At the cemetery in what is now the district of Pullach stood a memorial stone which was mentioned as recently as 1967, but which is no longer at the site. The suffering of ten unknown victims of the camp was recorded on the stone.
### Regular events {#regular_events}
- The Abensberger events calendar begins in February with the *Faschingsgillamoos* funfair, which reaches its high point on Mad Thursday.
- There then follows the *Frühjahrsmarkt* (Spring market) two weeks before Easter, when all the shops in the town are permitted to open on Sunday (which is normally prohibited in Germany).
-
- The *Bürgerfest* is celebrated on the first weekend of July, when the palace gardens with their ancient walls are transformed into a medieval camp.
- The *Schlossgartenfest* (Palace Garden Festival) takes place every year at the beginning of August. It is organised since 1977 by the Junge Union, the youth branch of Germany\'s two main conservative political parties, the CDU and CSU, and attracts all age groups from Abensberg and surrounding areas.
- On the second Saturday in August, people can wander through the Night Market in the balmy Summer evening.
- The *Gillamoos*, the oldest and largest funfair in the Hallertau opens on the Thursday before the first Sunday in September and runs until the Monday thereafter. It is the highlight of the year in Abensberg and is a celebration of the people of Abensberg and the surrounding area.
- The *Herbstmarkt* (autumn market), another Sunday shopping day, is on the first weekend in October.
- Since 1997, a series of cultural, art, music and entertainment events have taken place in November at various locations in the town, under the title, *Novembernebel* (November fog)
- On Saint Nicholas Day (6 December), the *Niklasmarkt* (Nicholas Market) commemorates the *Niklasspende*, a medieval foundation for the poor. This heralds the beginning of Advent and the Christmas period.
## Sport
### Speedway and football {#speedway_and_football}
The Wack Hofmeister Stadium, formerly the Altes Stadion Abensberg (the Old Stadium) is a motorcycle speedway and association football stadium located slightly east of the centre of Abensberg in Germany. It hosts the speedway team MSC Abensberg and the football team TSV Abensberg 1862.
## Notable residents {#notable_residents}
### Sons and daughters of the town {#sons_and_daughters_of_the_town}
- Johannes Aventinus (1477--1534): Bavarian historian
- Stephan Agricola (1491--1547): Lutheran reformer
- Joseph von Hazzi (1768--1845): Bavarian Privy Councillor
- Josef Hofmeister (born 1934): Speedway rider
- Uwe Brandl (born 1959): Mayor of Abensberg
- Paul Smaczny: Music and film producer
- Christian Lohr: Musician and producer
- Stephan Ebn (born 1978): drummer and music producer
- Richard Resch: Tenor, classical and opera singer
### People who have worked in the town {#people_who_have_worked_in_the_town}
- Wiguläus von Kreittmayr (1705--1790): by marriage Lord of Offenstetten and Hatzkofen
- Friedensreich Hundertwasser (1928--2000): artist and architect
- Radu Ivan (born 1969): International Judo champion
- Ole Bischof (born 1979): Olympic Judo champion
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1,309 |
Almost all
|
In mathematics, the term \"**almost all**\" means \"all but a negligible quantity\". More precisely, if $X$ is a set, \"almost all elements of $X$\" means \"all elements of $X$ but those in a negligible subset of $X$\". The meaning of \"negligible\" depends on the mathematical context; for instance, it can mean finite, countable, or null.
In contrast, \"**almost no**\" means \"a negligible quantity\"; that is, \"almost no elements of $X$\" means \"a negligible quantity of elements of $X$\".
## Meanings in different areas of mathematics {#meanings_in_different_areas_of_mathematics}
### Prevalent meaning {#prevalent_meaning}
Throughout mathematics, \"almost all\" is sometimes used to mean \"all (elements of an infinite set) except for finitely many\".`{{r|Cahen1|Cahen2}}`{=mediawiki} This use occurs in philosophy as well.`{{r|Gardenfors}}`{=mediawiki} Similarly, \"almost all\" can mean \"all (elements of an uncountable set) except for countably many\".`{{r|Schwartzman|group=sec}}`{=mediawiki}
Examples:
- Almost all positive integers are greater than 10^12^.`{{r|Courant|page=293}}`{=mediawiki}
- Almost all prime numbers are odd (2 is the only exception).
- Almost all polyhedra are irregular (as there are only nine exceptions: the five platonic solids and the four Kepler--Poinsot polyhedra).
- If P is a nonzero polynomial, then P(x) ≠ 0 for almost all x (if not all *x*).
### Meaning in measure theory {#meaning_in_measure_theory}
When speaking about the reals, sometimes \"almost all\" can mean \"all reals except for a null set\".`{{r|Korevaar|Natanson}}`{=mediawiki}`{{r|Clapham|group=sec}}`{=mediawiki} Similarly, if S is some set of reals, \"almost all numbers in S\" can mean \"all numbers in S except for those in a null set\".`{{r|Sohrab}}`{=mediawiki} The real line can be thought of as a one-dimensional Euclidean space. In the more general case of an n-dimensional space (where n is a positive integer), these definitions can be generalised to \"all points except for those in a null set\"`{{r|James|group=sec}}`{=mediawiki} or \"all points in S except for those in a null set\" (this time, S is a set of points in the space).`{{r|Helmberg}}`{=mediawiki} Even more generally, \"almost all\" is sometimes used in the sense of \"almost everywhere\" in measure theory,`{{r|Vestrup|Billingsley}}`{=mediawiki}`{{r|Bityutskov|group=sec}}`{=mediawiki} or in the closely related sense of \"almost surely\" in probability theory.`{{r|Billingsley}}`{=mediawiki}`{{r|Ito2|group=sec}}`{=mediawiki}
Examples:
- In a measure space, such as the real line, countable sets are null. The set of rational numbers is countable, so almost all real numbers are irrational.`{{r|Niven}}`{=mediawiki}
- Georg Cantor\'s first set theory article proved that the set of algebraic numbers is countable as well, so almost all reals are transcendental.`{{r|Baker}}`{=mediawiki}`{{r|group=sec|RealTrans}}`{=mediawiki}
- Almost all reals are normal.`{{r|Granville}}`{=mediawiki}
- The Cantor set is also null. Thus, almost all reals are not in it even though it is uncountable.`{{r|Korevaar}}`{=mediawiki}
- The derivative of the Cantor function is 0 for almost all numbers in the unit interval.`{{r|Burk}}`{=mediawiki} It follows from the previous example because the Cantor function is locally constant, and thus has derivative 0 outside the Cantor set.
### Meaning in number theory {#meaning_in_number_theory}
In number theory, \"almost all positive integers\" can mean \"the positive integers in a set whose natural density is 1\". That is, if A is a set of positive integers, and if the proportion of positive integers in *A* below n (out of all positive integers below n) tends to 1 as n tends to infinity, then almost all positive integers are in A.`{{r|Hardy1|Hardy2}}`{=mediawiki}`{{r|Weisstein|group=sec}}`{=mediawiki}
More generally, let S be an infinite set of positive integers, such as the set of even positive numbers or the set of primes, if A is a subset of S, and if the proportion of elements of S below n that are in A (out of all elements of S below n) tends to 1 as n tends to infinity, then it can be said that almost all elements of S are in A.
Examples:
- The natural density of cofinite sets of positive integers is 1, so each of them contains almost all positive integers.
- Almost all positive integers are composite.`{{r|Weisstein|group=sec}}`{=mediawiki}`{{refn |group=proof |The [[prime number theorem]] shows that the number of primes less than or equal to <var>n</var> is asymptotically equal to <var>n</var>/ln(<var>n</var>). Therefore, the proportion of primes is roughly ln(<var>n</var>)/<var>n</var>, which tends to 0 as <var>n</var> tends to [[infinity]], so the proportion of composite numbers less than or equal to <var>n</var> tends to 1 as <var>n</var> tends to infinity.{{r|Hardy2}}}}`{=mediawiki}
- Almost all even positive numbers can be expressed as the sum of two primes.`{{r|Courant|page=489}}`{=mediawiki}
- Almost all primes are isolated. Moreover, for every positive integer `{{mvar|g}}`{=mediawiki}, almost all primes have prime gaps of more than `{{mvar|g}}`{=mediawiki} both to their left and to their right; that is, there is no other prime between `{{math|''p'' − ''g''}}`{=mediawiki} and `{{math|''p'' + ''g''}}`{=mediawiki}.`{{r|Prachar}}`{=mediawiki}
### Meaning in graph theory {#meaning_in_graph_theory}
In graph theory, if A is a set of (finite labelled) graphs, it can be said to contain almost all graphs, if the proportion of graphs with n vertices that are in A tends to 1 as n tends to infinity.`{{r|Babai}}`{=mediawiki} However, it is sometimes easier to work with probabilities,`{{r|Spencer}}`{=mediawiki} so the definition is reformulated as follows. The proportion of graphs with n vertices that are in A equals the probability that a random graph with n vertices (chosen with the uniform distribution) is in A, and choosing a graph in this way has the same outcome as generating a graph by flipping a coin for each pair of vertices to decide whether to connect them.`{{r|Bollobas}}`{=mediawiki} Therefore, equivalently to the preceding definition, the set *A* contains almost all graphs if the probability that a coin-flip--generated graph with n vertices is in A tends to 1 as n tends to infinity.`{{r|Spencer|Gradel}}`{=mediawiki} Sometimes, the latter definition is modified so that the graph is chosen randomly in some other way, where not all graphs with n vertices have the same probability,`{{r|Bollobas}}`{=mediawiki} and those modified definitions are not always equivalent to the main one.
The use of the term \"almost all\" in graph theory is not standard; the term \"asymptotically almost surely\" is more commonly used for this concept.`{{r|Spencer}}`{=mediawiki}
Example:
- Almost all graphs are asymmetric.`{{r|Babai}}`{=mediawiki}
- Almost all graphs have diameter 2.`{{r|Buckley}}`{=mediawiki}
### Meaning in topology {#meaning_in_topology}
In topology`{{r|Oxtoby}}`{=mediawiki} and especially dynamical systems theory`{{r|Baratchart|Broer|Sharkovsky}}`{=mediawiki} (including applications in economics),`{{r|Yuan}}`{=mediawiki} \"almost all\" of a topological space\'s points can mean \"all of the space\'s points except for those in a meagre set\". Some use a more limited definition, where a subset contains almost all of the space\'s points only if it contains some open dense set.`{{r|Broer|Albertini|Fuente}}`{=mediawiki}
Example:
- Given an irreducible algebraic variety, the properties that hold for almost all points in the variety are exactly the generic properties.`{{r|Ito1|group=sec}}`{=mediawiki} This is due to the fact that in an irreducible algebraic variety equipped with the Zariski topology, all nonempty open sets are dense.
### Meaning in algebra {#meaning_in_algebra}
In abstract algebra and mathematical logic, if U is an ultrafilter on a set X, \"almost all elements of X\" sometimes means \"the elements of some *element* of U\".`{{r|Komjath|Salzmann|Schoutens|Rautenberg}}`{=mediawiki} For any partition of X into two disjoint sets, one of them will necessarily contain almost all elements of X. It is possible to think of the elements of a filter on X as containing almost all elements of X, even if it isn\'t an ultrafilter.`{{r|Rautenberg}}`{=mediawiki}
## Proofs
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1,313 |
Aromatic compound
|
**Aromatic compounds** or **arenes** are organic compounds \"with a chemistry typified by benzene\" and \"cyclically conjugated.\" The word \"aromatic\" originates from the past grouping of molecules based on odor, before their general chemical properties were understood. The current definition of aromatic compounds does not have any relation to their odor. Aromatic compounds are now defined as cyclic compounds satisfying Hückel\'s rule. Aromatic compounds have the following general properties:
- Typically unreactive
- Often non polar and hydrophobic
- High carbon-hydrogen ratio
- Burn with a strong sooty yellow flame, due to high C:H ratio
- Undergo electrophilic substitution reactions and nucleophilic aromatic substitutions
Arenes are typically split into two categories - benzoids, that contain a benzene derivative and follow the benzene ring model, and non-benzoids that contain other aromatic cyclic derivatives. Aromatic compounds are commonly used in organic synthesis and are involved in many reaction types, following both additions and removals, as well as saturation and dearomatization.
## Heteroarenes
**Heteroarenes** are aromatic compounds, where at least one methine or vinylene (-C= or -CH=CH-) group is replaced by a heteroatom: oxygen, nitrogen, or sulfur. Examples of non-benzene compounds with aromatic properties are furan, a heterocyclic compound with a five-membered ring that includes a single oxygen atom, and pyridine, a heterocyclic compound with a six-membered ring containing one nitrogen atom. Hydrocarbons without an aromatic ring are called aliphatic. Approximately half of compounds known in 2000 are described as aromatic to some extent.
## Applications
Aromatic compounds are pervasive in nature and industry. Key industrial aromatic hydrocarbons are benzene, toluene, xylene called BTX. Many biomolecules have phenyl groups including the so-called aromatic amino acids.
## Benzene ring model {#benzene_ring_model}
Benzene, C~6~H~6~, is the least complex aromatic hydrocarbon, and it was the first one defined as such. Its bonding nature was first recognized independently by Joseph Loschmidt and August Kekulé in the 19th century. Each carbon atom in the hexagonal cycle has four electrons to share. One electron forms a sigma bond with the hydrogen atom, and one is used in covalently bonding to each of the two neighboring carbons. This leaves six electrons, shared equally around the ring in delocalized pi molecular orbitals the size of the ring itself. This represents the equivalent nature of the six carbon-carbon bonds all of bond order 1.5. This equivalency can also explained by resonance forms. The electrons are visualized as floating above and below the ring, with the electromagnetic fields they generate acting to keep the ring flat.
The circle symbol for aromaticity was introduced by Sir Robert Robinson and his student James Armit in 1925 and popularized starting in 1959 by the Morrison & Boyd textbook on organic chemistry. The proper use of the symbol is debated: some publications use it to *any* cyclic π system, while others use it only for those π systems that obey Hückel\'s rule. Some argue that, in order to stay in line with Robinson\'s originally intended proposal, the use of the circle symbol should be limited to monocyclic 6 π-electron systems. In this way the circle symbol for a six-center six-electron bond can be compared to the Y symbol for a three-center two-electron bond.
## Benzene and derivatives of benzene {#benzene_and_derivatives_of_benzene}
Benzene derivatives have from one to six substituents attached to the central benzene core. Examples of benzene compounds with just one substituent are phenol, which carries a hydroxyl group, and toluene with a methyl group. When there is more than one substituent present on the ring, their spatial relationship becomes important for which the arene substitution patterns *ortho*, *meta*, and *para* are devised. When reacting to form more complex benzene derivatives, the substituents on a benzene ring can be described as either activated or deactivated, which are electron donating and electron withdrawing respectively. Activators are known as ortho-para directors, and deactivators are known as meta directors. Upon reacting, substituents will be added at the ortho, para or meta positions, depending on the directivity of the current substituents to make more complex benzene derivatives, often with several isomers. Electron flow leading to re-aromatization is key in ensuring the stability of such products.
For example, three isomers exist for cresol because the methyl group and the hydroxyl group (both ortho para directors) can be placed next to each other (*ortho*), one position removed from each other (*meta*), or two positions removed from each other (*para*). Given that both the methyl and hydroxyl group are ortho-para directors, the ortho and para isomers are typically favoured. Xylenol has two methyl groups in addition to the hydroxyl group, and, for this structure, 6 isomers exist.
Arene rings can stabilize charges, as seen in, for example, phenol (C~6~H~5~--OH), which is acidic at the hydroxyl (OH), as charge on the oxygen (alkoxide --O^−^) is partially delocalized into the benzene ring.
<File:Benzene-Kekule-2D-skeletal.png>\|Benzene <File:Toluol.svg>\|Toluene <File:Ethylbenzol.svg>\|Ethylbenzene <File:Cumol.svg>\|Cumene <File:Para-Xylol> - para-xylene.svg\|*p*-Xylene <File:Meta-Xylol> - meta-xylene.svg\|*m*-Xylene <File:Ortho-Xylol> - ortho-xylene.svg\|*o*-Xylene <File:Mesitylen.svg>\|Mesitylene <File:1,2,4,5-Tetramethylbenzol.svg>\|Durene <File:Biphenyl.svg>\|Biphenyl <File:Phenol.svg>\|Phenol <File:Aniline.svg>\|Aniline <File:Benzaldehyde.svg>\|Benzaldehyde <File:Benzoic> acid.svg\|Benzoic acid <File:Benzamide.svg>\|Benzamide <File:Acetophenone> structure.svg\|Acetophenone
## Non-benzylic arenes {#non_benzylic_arenes}
Although benzylic arenes are common, non-benzylic compounds are also exceedingly important. Any compound containing a cyclic portion that conforms to Hückel\'s rule and is not a benzene derivative can be considered a non-benzylic aromatic compound.
### Monocyclic arenes {#monocyclic_arenes}
Of annulenes larger than benzene, \[12\]annulene and \[14\]annulene are weakly aromatic compounds and \[18\]annulene, Cyclooctadecanonaene, is aromatic, though strain within the structure causes a slight deviation from the precisely planar structure necessary for aromatic categorization. Another example of a non-benzylic monocyclic arene is the cyclopropenyl (cyclopropenium cation), which satisfies Hückel\'s rule with an n equal to 0. Note, only the cationic form of this cyclic propenyl is aromatic, given that neutrality in this compound would violate either the octet rule or Hückel\'s rule.
Other non-benzylic monocyclic arenes include the aforementioned heteroarenes that can replace carbon atoms with other heteroatoms such as N, O or S. Common examples of these are the five-membered pyrrole and six-membered pyridine, both of which have a substituted nitrogen
### Polycyclic aromatic hydrocarbons {#polycyclic_aromatic_hydrocarbons}
*Main article: Polycyclic aromatic hydrocarbon*
Polycyclic aromatic hydrocarbons, also known as polynuclear aromatic compounds (PAHs) are aromatic hydrocarbons that consist of fused aromatic rings and do not contain heteroatoms or carry substituents. Naphthalene is the simplest example of a PAH. PAHs occur in oil, coal, and tar deposits, and are produced as byproducts of fuel burning (whether fossil fuel or biomass). As pollutants, they are of concern because some compounds have been identified as carcinogenic, mutagenic, and teratogenic. PAHs are also found in cooked foods. Studies have shown that high levels of PAHs are found, for example, in meat cooked at high temperatures such as grilling or barbecuing, and in smoked fish. They are also a good candidate molecule to act as a basis for the earliest forms of life. In graphene the PAH motif is extended to large 2D sheets.
## Reactions
Aromatic ring systems participate in many organic reactions.
### Substitution
In aromatic substitution, one substituent on the arene ring, usually hydrogen, is replaced by another reagent. The two main types are electrophilic aromatic substitution, when the active reagent is an electrophile, and nucleophilic aromatic substitution, when the reagent is a nucleophile. In radical-nucleophilic aromatic substitution, the active reagent is a radical.
An example of electrophilic aromatic substitution is the nitration of salicylic acid, where a nitro group is added para to the hydroxide substituent:
:
Nucleophilic aromatic substitution involves displacement of a leaving group, such as a halide, on an aromatic ring. Aromatic rings usually nucleophilic, but in the presence of electron-withdrawing groups aromatic compounds undergo nucleophilic substitution. Mechanistically, this reaction differs from a common S~N~2 reaction, because it occurs at a trigonal carbon atom (sp^2^ hybridization).
### Hydrogenation
Hydrogenation of arenes create saturated rings. The compound 1-naphthol is completely reduced to a mixture of decalin-ol isomers.
:
The compound resorcinol, hydrogenated with Raney nickel in presence of aqueous sodium hydroxide forms an enolate which is alkylated with methyl iodide to 2-methyl-1,3-cyclohexandione:
:
### Dearomatization
In dearomatization reactions the aromaticity of the reactant is lost. In this regard, the dearomatization is related to hydrogenation. A classic approach is Birch reduction. The methodology is used in synthesis.
## Arene-arene interactions {#arene_arene_interactions}
Arene-arene interactions have attracted much attention. Pi-stacking (also called **π--π stacking**) refers to the presumptively attractive, noncovalent pi interactions between the pi bonds of aromatic rings, because of orbital overlap. According to some authors direct stacking of aromatic rings (the \"sandwich interaction\") is electrostatically repulsive.
More commonly observed are either a **staggered stacking** (parallel displaced) or **pi-teeing** (perpendicular T-shaped) interaction both of which are electrostatic attractive For example, the most commonly observed interactions between aromatic rings of amino acid residues in proteins is a staggered stacked followed by a perpendicular orientation. Sandwiched orientations are relatively rare.
Pi stacking is repulsive as it places carbon atoms with partial negative charges from one ring on top of other partial negatively charged carbon atoms from the second ring and hydrogen atoms with partial positive charges on top of other hydrogen atoms that likewise carry partial positive charges. In staggered stacking, one of the two aromatic rings is offset sideways so that the carbon atoms with partial negative charge in the first ring are placed above hydrogen atoms with partial positive charge in the second ring so that the electrostatic interactions become attractive. Likewise, pi-teeing interactions in which the two rings are oriented perpendicular to either other is electrostatically attractive as it places partial positively charged hydrogen atoms in close proximity to partially negatively charged carbon atoms. An alternative explanation for the preference for staggered stacking is due to the balance between van der Waals interactions (attractive dispersion plus Pauli repulsion).
These staggered stacking and π-teeing interactions between aromatic rings are important in nucleobase stacking within DNA and RNA molecules, protein folding, template-directed synthesis, materials science, and molecular recognition. Despite the wide use of term pi stacking in the scientific literature, there is no theoretical justification for its use.
### Benzene dimer {#benzene_dimer}
thumb\|right\|upright=1.8\|Three representative conformations of the benzene dimer
The benzene dimer is the prototypical system for the study of pi stacking, and is experimentally bound by 8--12 kJ/mol (2--3 kcal/mol) in the gas phase with a separation of 4.96 Å between the centers of mass for the T-shaped dimer. X-ray crystallography reveals perpendicular and offset parallel configurations for many simple aromatic compounds. Similar offset parallel or perpendicular geometries were observed in a survey of high-resolution x-ray protein crystal structures in the Protein Data Bank. Analysis of the aromatic amino acids phenylalanine, tyrosine, histidine, and tryptophan indicates that dimers of these side chains have many stabilizing interactions at distances larger than the average van der Waals radii.
The relative binding energies of the three geometries of the benzene dimer can be explained by a balance of quadrupole/quadrupole and London dispersion forces. While benzene does not have a dipole moment, it has a strong quadrupole moment. The local C--H dipole means that there is positive charge on the atoms in the ring and a correspondingly negative charge representing an electron cloud above and below the ring. The quadrupole moment is reversed for hexafluorobenzene due to the electronegativity of fluorine. The benzene dimer in the sandwich configuration is stabilized by London dispersion forces but destabilized by repulsive quadrupole/quadrupole interactions. By offsetting one of the benzene rings, the parallel displaced configuration reduces these repulsive interactions and is stabilized. The large polarizability of aromatic rings lead to dispersive interactions as major contribution to stacking effects. These play a major role for interactions of nucleobases e.g. in DNA. The T-shaped configuration enjoys favorable quadrupole/quadrupole interactions, as the positive quadrupole of one benzene ring interacts with the negative quadrupole of the other. The benzene rings are furthest apart in this configuration, so the favorable quadrupole/quadrupole interactions evidently compensate for diminished dispersion forces.
According to one model, electron-withdrawing substituents lowers the negative quadrupole of the aromatic ring and thereby favor parallel displaced and sandwich conformations. By contrast, electron donating groups increase the negative quadrupole, which may stabilize a T-shaped configuration with the proper geometry. They used a simple mathematical model based on sigma and pi atomic charges, relative orientations, and van der Waals interactions to qualitatively determine that electrostatics are dominant in substituent effects.
thumb\|right\|upright=2.3\|Double mutant cycle used by Hunter et al. to probe T-shaped π-stacking interactions Hunter *et al.* applied a more sophisticated chemical double mutant cycle with a hydrogen-bonded \"zipper\" to the issue of substituent effects in pi stacking interactions in proteins. However, the authors note that direct interactions with the ring substituents, discussed below, also make important contributions. Indeed, the interplay of these two factors may result in the complicated substituent- and geometry-dependent behavior of pi stacking interactions.
Some experimental and computational evidence suggests that pi stacking interactions are not governed primarily by electrostatic effects..
The relative contributions pi stacking have been borne out by computation. Trends based on electron donating or withdrawing substituents can be explained by exchange-repulsion and dispersion terms.
A molecular torsion balance from an aryl ester with two conformational states. The folded state had a well-defined pi stacking interaction with a T-shaped geometry, whereas the unfolded state had no aryl--aryl interactions. The NMR chemical shifts of the two conformations were distinct and could be used to determine the ratio of the two states, which was interpreted as a measure of intramolecular forces. The authors report that a preference for the folded state is not unique to aryl esters. For example, the cyclohexyl ester favored the folded state more so than the phenyl ester, and the tert-butyl ester favored the folded state by a preference greater than that shown by any aryl ester. This suggests that aromaticity is not a strict requirement for favorable interaction with an aromatic ring.
Other evidence for non-aromatic pi stacking interactions results include critical studies in theoretical chemistry, explaining the underlying mechanisms of empirical observations. Grimme reported that the interaction energies of smaller dimers consisting of one or two rings are very similar for both aromatic and saturated compounds. This finding is of particular relevance to biology, and suggests that the contribution of pi systems to phenomena such as stacked nucleobases may be overestimated. However, it was shown that an increased stabilizing interaction is seen for large aromatic dimers. As previously noted, this interaction energy is highly dependent on geometry. Indeed, large aromatic dimers are only stabilized relative to their saturated counterparts in a sandwich geometry, while their energies are similar in a T-shaped interaction.
A more direct approach to modeling the role of aromaticity was taken by Bloom and Wheeler. The authors compared the interactions between benzene and either 2-methylnaphthalene or its non-aromatic isomer, 2-methylene-2,3-dihydronaphthalene. The latter compound provides a means of conserving the number of p-electrons while, however, removing the effects of delocalization. Surprisingly, the interaction energies with benzene are higher for the non-aromatic compound, suggesting that pi-bond localization is favorable in pi stacking interactions. The authors also considered a homodesmotic dissection of benzene into ethylene and 1,3-butadiene and compared these interactions in a sandwich with benzene. Their calculation indicates that the interaction energy between benzene and homodesmotic benzene is higher than that of a benzene dimer in both sandwich and parallel displaced conformations, again highlighting the favorability of localized pi-bond interactions. These results strongly suggest that aromaticity is not required for pi stacking interactions in this model.
Even in light of this evidence, Grimme concludes that pi stacking does indeed exist. However, he cautions that smaller rings, particularly those in T-shaped conformations, do not behave significantly differently from their saturated counterparts, and that the term should be specified for larger rings in stacked conformations which do seem to exhibit a cooperative pi electron effect.
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1,316 |
Annales school
|
The ***Annales* school** (`{{IPA|fr|a'nal}}`{=mediawiki}) is a group of historians associated with a style of historiography developed by French historians in the 20th century to stress long-term social history. It is named after its scholarly journal *Annales. Histoire, Sciences Sociales*, which remains the main source of scholarship, along with many books and monographs. The school has been influential in setting the agenda for historiography in France and numerous other countries, especially regarding the use of social scientific methods by historians, emphasizing social and economic rather than political or diplomatic themes.
The school deals primarily with late medieval and early modern Europe (before the French Revolution), with little interest in later topics. It has dominated French social history and heavily influenced historiography in Europe and Latin America. Prominent leaders include co-founders Lucien Febvre (1878--1956), Henri Hauser (1866--1946) and Marc Bloch (1886--1944). The second generation was led by Fernand Braudel (1902--1985) and included Georges Duby (1919--1996), Pierre Goubert (1915--2012), Robert Mandrou (1921--1984), Pierre Chaunu (1923--2009), Jacques Le Goff (1924--2014), and Ernest Labrousse (1895--1988). Institutionally it is based on the *Annales* journal, the SEVPEN publishing house, the *Fondation Maison des sciences de l\'homme* (FMSH), and especially the 6th Section of the École pratique des hautes études, all based in Paris. A third generation was led by Emmanuel Le Roy Ladurie (1929--2023) and includes Jacques Revel, and Philippe Ariès (1914--1984), who joined the group in 1978. The third generation stressed history from the point of view of mentalities, or *mentalités*. The fourth generation of *Annales* historians, led by Roger Chartier (born 1945), clearly distanced itself from the *mentalités* approach, replaced by the cultural and linguistic turn, which emphasizes the social history of cultural practices.
The main scholarly outlet has been the journal *Annales d\'Histoire Economique et Sociale* (\"Annals of Economic and Social History\"), founded in 1929 by Lucien Febvre and Marc Bloch, which broke radically with traditional historiography by insisting on the importance of taking all levels of society into consideration and emphasized the collective nature of mentalities. Its contributors viewed events as less fundamental than the mental frameworks that shaped decisions and practices. However, informal successor as head of the school was Le Roy Ladurie. Multiple responses were attempted by the school. Scholars moved in multiple directions, covering in disconnected fashion the social, economic, and cultural history of different eras and different parts of the globe. By the time of the crisis the school was building a vast publishing and research network reaching across France, Europe, and the rest of the world. Influence spread out from Paris, but few new ideas came in. Much emphasis was given to quantitative data, seen as the key to unlocking all of social history. However, the *Annales* ignored the developments in quantitative studies underway in the U.S. and Britain, which reshaped economic, political, and demographic research. An attempt to require an *Annales*-written textbook for French schools was rejected by the government. By 1980 postmodern sensibilities undercut confidence in overarching metanarratives. As Jacques Revel notes, the success of the *Annales* school, especially its use of social structures as explanatory forces, contained the seeds of its own downfall, for there is \"no longer any implicit consensus on which to base the unity of the social, identified with the real\". The *Annales* school kept its infrastructure, but lost its *mentalités*.
## The journal {#the_journal}
The journal began in Strasbourg as *Annales d\'histoire économique et sociale*; it moved to Paris and kept the same name from 1929 to 1939. It was successively renamed *Annales d\'histoire sociale* (1939--1942, 1945), *Mélanges d\'histoire sociale* (1942--1944), *Annales. Economies, sociétés, civilisations* (1946--1994), and *Annales. Histoire, Sciences Sociales* (1994-- ).
In 1962, Braudel and Gaston Berger used Ford Foundation money and government funds to create a new independent foundation, the *Fondation Maison des sciences de l\'homme* (FMSH), which Braudel directed from 1970 until his death. In 1970, the 6th Section and the *Annales* relocated to the FMSH building. FMSH set up elaborate international networks to spread the *Annales* gospel across Europe and the world. In 2013, it began publication of an English language edition, with all the articles translated.
The scope of topics covered by the journal is vast and experimental---there is a search for total history and new approaches. The emphasis is on social history, and very long-term trends, often using quantification and paying special attention to geography and to the intellectual world view of common people, or \"mentality\" (*mentalité*). Little attention is paid to political, diplomatic, or military history, or to biographies of famous men. Instead the *Annales* focused attention on the synthesizing of historical patterns identified from social, economic, and cultural history, statistics, medical reports, family studies, and even psychoanalysis.
## Origins
The *Annales* was founded and edited by Marc Bloch and Lucien Febvre in 1929, while they were teaching at the University of Strasbourg and later in Paris. These authors, the former a medieval historian and the latter an early modernist, quickly became associated with the distinctive *Annales* approach, which combined geography, history, and the sociological approaches of the *\[\[Année Sociologique\]\]* (many members of which were their colleagues at Strasbourg) to produce an approach which rejected the predominant emphasis on politics, diplomacy and war of many 19th and early 20th-century historians as spearheaded by historians whom Febvre called Les Sorbonnistes. Instead, they pioneered an approach to a study of long-term historical structures (*la \[\[longue durée\]\]*) over events and political transformations. Geography, material culture, and what later Annalistes called *mentalités*, or the psychology of the epoch, are also characteristic areas of study. The goal of the Annales was to undo the work of the Sorbonnistes, to turn French historians away from the narrowly political and diplomatic toward the new vistas in social and economic history.
Co-founder Marc Bloch (1886--1944) was a quintessential modernist who studied at the elite École Normale Supérieure, and in Germany, serving as a professor at the University of Strasbourg until he was called to the Sorbonne in Paris in 1936 as professor of economic history. Bloch\'s interests were highly interdisciplinary, influenced by the geography of Paul Vidal de la Blache (1845--1918) and the sociology of Émile Durkheim (1858--1917). His own ideas, especially those expressed in his masterworks, *French Rural History* (*Les caractères originaux de l\'histoire rurale française*, 1931) and *Feudal Society*, were incorporated by the second-generation Annalistes, led by Fernand Braudel.
## Precepts
Georges Duby, a leader of the school, wrote that the history he taught:
: relegated the sensational to the sidelines and was reluctant to give a simple accounting of events, but strove on the contrary to pose and solve problems and, neglecting surface disturbances, to observe the long and medium-term evolution of economy, society and civilisation.
The Annalistes, especially Lucien Febvre, advocated a *histoire totale*, or *histoire tout court*, a complete study of a historic problem.
## Postwar
Bloch was shot by the Gestapo during the German occupation of France in World War II for his active membership of the French Resistance, and Febvre carried on the *Annales* approach in the 1940s and 1950s. It was during this time that he mentored Braudel, who would become one of the best-known exponents of this school. Braudel\'s work came to define a \"second\" era of *Annales* historiography and was influential throughout the 1960s and 1970s, especially for his work on the Mediterranean region in the era of Philip II of Spain. Braudel developed the idea, often associated with Annalistes, of different modes of historical time: *l\'histoire quasi immobile* (the quasi motionless history) of historical geography, the history of social, political and economic structures (*la \[\[longue durée\]\]*), and the history of men and events, in the context of their structures.
While authors such as Emmanuel Le Roy Ladurie, Marc Ferro and Jacques Le Goff continue to carry the *Annales* banner, today the *Annales* approach has been less distinctive as more and more historians do work in cultural history, political history and economic history.
## *Mentalités* {#section}
Bloch\'s *\[\[Les Rois thaumaturges\]\]* (1924) looked at the long-standing folk belief that the king could cure scrofula by his thaumaturgic touch. The kings of France and England indeed regularly practiced the ritual. Bloch was not concerned with the effectiveness of the royal touch---he acted instead like an anthropologist in asking why people believed it and how it shaped relations between king and commoner. The book was highly influential in introducing comparative studies (in this case France and England), as well as long durations (\"longue durée\") studies spanning several centuries, even up to a thousand years, downplaying short-term events. Bloch\'s revolutionary charting of mentalities, or *mentalités*, resonated with scholars who were reading Freud and Proust. In the 1960s, Robert Mandrou and Georges Duby harmonized the concept of *mentalité* history with Fernand Braudel\'s structures of historical time and linked mentalities with changing social conditions. A flood of *mentalité* studies based on these approaches appeared during the 1970s and 1980s. By the 1990s, however, *mentalité* history had become interdisciplinary to the point of fragmentation, but still lacked a solid theoretical basis. While not explicitly rejecting *mentalité* history, younger historians increasingly turned to other approaches.
## Braudel
Fernand Braudel became the leader of the second generation after 1945. He obtained funding from the Rockefeller Foundation in New York and founded the 6th Section of the Ecole Pratique des Hautes Etudes, which was devoted to the study of history and the social sciences. It became an independent degree-granting institution in 1975 under the name École des Hautes Études en Sciences Sociales (EHESS). Braudel\'s followers admired his use of the *longue durée* approach to stress slow, and often imperceptible effects of space, climate and technology on the actions of human beings in the past. The *Annales* historians, after living through two world wars and incredible political upheavals in France, were deeply uncomfortable with the notion that multiple ruptures and discontinuities created history. They preferred to stress inertia and the longue durée. Special attention was paid to geography, climate, and demography as long-term factors. They believed the continuities of the deepest structures were central to history, beside which upheavals in institutions or the superstructure of social life were of little significance, for history lies beyond the reach of conscious actors, especially the will of revolutionaries. They rejected the Marxist idea that history should be used as a tool to foment and foster revolutions. In turn the Marxists called them conservatives.
Braudel\'s first book, *La Méditerranée et le Monde Méditerranéen à l\'Epoque de Philippe II* (1949) (*The Mediterranean and the Mediterranean World in the Age of Philip II*), was his most influential. This vast panoramic view used ideas from other social sciences, employed effectively the technique of the longue durée, and downplayed the importance of specific events and individuals. It stressed geography but not *mentalité*. It was widely admired, but most historians did not try to replicate it and instead focused on their specialized monographs. The book dramatically raised the worldwide profile of the Annales School.
In 1951, historian Bernard Bailyn published a critique of *La Méditerranée et le Monde Méditerranéen à l\'Epoque de Philippe II*, which he framed as dichotomizing politics and society.
## Regionalism
Before *Annales*, French history supposedly happened in Paris. Febvre broke decisively with this paradigm in 1912, with his sweeping doctoral thesis on *Philippe II\]\] et la \[\[Franche-Comté\]\]*. The geography and social structure of this region overwhelmed and shaped the king\'s policies.
The *Annales* historians did not try to replicate Braudel\'s vast geographical scope in *La Méditerranée*. Instead they focused on regions in France over long stretches of time. The most important was the study of *The Peasants of Languedoc* by Braudel\'s star pupil and successor Emmanuel Le Roy Ladurie. The regionalist tradition flourished especially in the 1960s and 1970s in the work of Pierre Goubert in 1960 on Beauvais and René Baehrel on Basse-Provence. *Annales* historians in the 1970s and 1980s turned to urban regions, including Pierre Deyon (Amiens), Maurice Garden (Lyon), Jean-Pierre Bardet (Rouen), Georges Freche (Toulouse), Gregory Hanlon (Agen and Layrac), and Jean-Claude Perrot (Caen). By the 1970s the shift was underway from the earlier economic history to cultural history and the history of mentalities.
## Impact outside France {#impact_outside_france}
The *Annales* school systematically reached out to create an impact on other countries. Its success varied widely. The *Annales* approach was especially well received in Italy and Poland. Franciszek Bujak (1875--1953) and Jan Rutkowski (1886--1949), the founders of modern economic history in Poland and of the journal *Roczniki Dziejów Spolecznych i Gospodarczych* (1931-- ), were attracted to the innovations of the Annales school. Rutkowski was in contact with Bloch and others, and published in the *Annales*. After the Communists took control in the 1940s Polish scholars were safer working on the Middle Ages and the early modern era rather than contemporary history. After the \"Polish October\" of 1956 the Sixth Section in Paris welcomed Polish historians and exchanges between the circle of the *Annales* and Polish scholars continued until the early 1980s. The reciprocal influence between the French school and Polish historiography was particularly evident in studies on the Middle Ages and the early modern era studied by Braudel.
In South America the *Annales* approach became popular. From the 1950s Federico Brito Figueroa was the founder of a new Venezuelan historiography based largely on the ideas of the Annales School. Brito Figueroa carried his conception of the field to all levels of university study, emphasizing a systematic and scientific approach to history and placing it squarely in the social sciences. Spanish historiography was influenced by the \"Annales School\" starting in 1950 with Jaume Vicens Vives (1910--1960). In Mexico, exiled Republican intellectuals extended the Annales approach, particularly from the Center for Historical Studies of El Colegio de México, the leading graduate studies institution of Latin America.
British historians, apart from a few Marxists, were generally hostile. Academic historians decidedly sided with Geoffrey Elton\'s *The Practice of History* against Edward Hallett Carr\'s *What Is History?* One of the few British historians who were sympathetic towards the work of the *Annales* school was Hugh Trevor-Roper. Among American academics, founding figure in American history of technology Lynn White Jr. dedicated his seminal and controversial book *Medieval Technology and Social Change* to *Annales* founder Marc Bloch. Both the American and the *Annales* historians picked up important family reconstitution techniques from French demographer Louis Henry.
The Wageningen school centered on Bernard Slicher van Bath was viewed internationally as a Dutch counterpart of the Annales school, although Slicher van Bath himself vehemently rejected the idea of a quantitative \"school\" of historiography.
The *Annales* school has been cited as a key influence in the development of World Systems Theory by sociologist Immanuel Wallerstein.
## Current
The current leader is Roger Chartier, who is Directeur d\'Études at the École des Hautes Études en Sciences Sociales in Paris, Professeur in the Collège de France, and Annenberg Visiting professor of history at the University of Pennsylvania. He frequently lectures and teaches in the United States, Spain, Mexico, Brazil and Argentina. His work in Early Modern European History focuses on the history of education, the history of the book and the history of reading. Recently, he has been concerned with the relationship between written culture as a whole and literature (particularly theatrical plays) for France, England and Spain. His work in this specific field (based on the criss-crossing between literary criticism, bibliography, and sociocultural history) is connected to broader historiographical and methodological interests which deal with the relation between history and other disciplines: philosophy, sociology, anthropology.
Chartier\'s typical undergraduate course focuses upon the making, remaking, dissemination, and reading of texts in early modern Europe and America. Under the heading of \"practices\", his class considers how readers read and marked up their books, forms of note-taking, and the interrelation between reading and writing from copying and translating to composing new texts. Under the heading of \"materials\", his class examines the relations between different kinds of writing surfaces (including stone, wax, parchment, paper, walls, textiles, the body, and the heart), writing implements (including styluses, pens, pencils, needles, and brushes), and material forms (including scrolls, erasable tables, codices, broadsides and printed forms and books). Under the heading of \"places\", his class explores where texts were made, read, and listened to, including monasteries, schools and universities, offices of the state, the shops of merchants and booksellers, printing houses, theaters, libraries, studies, and closets. The texts for his course include the *Bible*, translations of Ovid, *Hamlet*, *Don Quixote*, Montaigne\'s essays, Pepys\'s diary, Richardson\'s *Pamela*, and Franklin\'s autobiography.
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Casa Batlló
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***italic=no*** (`{{IPA|ca|ˈkazə βəˈʎːo|-|Ca-Casa Batlló.oga}}`{=mediawiki}) is a building in the center of Barcelona, Spain. It was designed by Antoni Gaudí, and is considered one of his masterpieces. A remodel of a previously built house, it was redesigned in 1904 by Gaudí (but the actual construction works hadn\'t begun at this point) and has been refurbished several times since. Gaudí\'s assistants Domènec Sugrañes i Gras, Josep Canaleta and Joan Rubió also contributed to the renovation project.
The local name for the building is **Casa dels ossos** (House of Bones), as it has a visceral, skeletal organic quality. It is located on the *italic=no* in the Eixample district, and forms part of a row of houses known as the *\[\[Illa de la Discòrdia\]\]* (or *Mansana de la Discòrdia*, the \"Block of Discord\"), which consists of four buildings by noted *Modernista\]\]* architects of Barcelona.
Like everything Gaudí designed, *italic=no* is only identifiable as *\[\[Modernisme\]\]* in the broadest sense. The ground floor, in particular, has unusual tracery, irregular oval windows and flowing sculpted stone work. There are few straight lines, and much of the façade is decorated with a colorful mosaic made of broken ceramic tiles (*\[\[trencadís\]\]*). The roof is arched and was likened to the back of a dragon or dinosaur. A common theory about the building is that the rounded feature to the left of centre, terminating at the top in a turret and cross, represents the lance of Saint George (patron saint of Catalonia, Gaudí\'s home), which has been plunged into the back of the dragon.
In 2005, *italic=no* became an UNESCO World Heritage Site.
## History
### Initial construction (1877) {#initial_construction_1877}
The building that is now *italic=no* was built in 1877, commissioned by Lluís Sala Sánchez. It was a classical building without remarkable characteristics within the eclecticism traditional by the end of the 19th century. The building had a basement, a ground floor, four other floors and a garden in the back.
### Batlló family {#batlló_family}
The house was bought by Josep Batlló in 1903. The design of the house made the home undesirable to buyers but the Batlló family decided to buy the place due to its centralized location. It is located in the middle of *italic=no*, which in the early 20th century was known as a very prestigious and fashionable area. It was an area where the prestigious family could draw attention to themselves.
In 1906, Josep Batlló still owned the home. The Batlló family was very well known in Barcelona for its contribution to the textile industry in the city. Josep Batlló i Casanovas was a textile industrialist who owned a few factories in the city. Batlló married Amàlia Godó Belaunzarán, from the family that founded the newspaper *La Vanguardia*. Josep wanted an architect that would design a house that was like no other and stood out as being audacious and creative. Both Josep and his wife were open to anything and they decided not to limit Gaudí. Josep did not want his house to resemble any of the houses of the rest of the Batlló family, such as Casa Pía, built by the Josep Vilaseca. He chose the architect who had designed Park Güell because he wanted him to come up with a risky plan. The family lived on the principal floor of *italic=no* until the middle of the 1950s.
### Renovation (1904-1906) {#renovation_1904_1906}
In 1904, Josep Batlló hired Gaudí to design his home; at first his plans were to tear down the building and construct a completely new house. Gaudí convinced Josep that a renovation was sufficient and was also able to submit the planning application the same year. The building was completed and refurbished in 1906. He completely changed the main apartment which became the residence for the Batlló family. He expanded the central well in order to supply light to the whole building and also added new floors. In the same year the Barcelona City Council selected the house as a candidate for that year\'s best building award. The award was given to another architect that year despite Gaudí\'s design.
### Refurbishments
Josep Batlló died in 1934 and the house was kept in order by the wife until her death in 1940. After the death of the two parents, the house was kept and managed by the children until 1954. In 1954, an insurance company named Seguros Iberia acquired Casa Batlló and set up offices there. In 1970, the first refurbishment occurred mainly in several of the interior rooms of the house. In 1983, the exterior balconies were restored to their original colour and a year later the exterior façade was illuminated in the ceremony of La Mercè.
### Multiple uses {#multiple_uses}
In 1993, the current owners of Casa Batlló bought the home and continued refurbishments throughout the whole building. Two years later, in 1995, Casa Batlló began to hire out its facilities for different events. More than 2,500 square meters of rooms within the building were rented out for many different functions. Due to the building\'s location and the beauty of the facilities being rented, the rooms of Casa Batlló were in very high demand and hosted many important events for the city.
## Design
### Overview
The local name for the building is *Casa dels ossos* (House of Bones), as it has a visceral, skeletal organic quality. The building looks very remarkable --- like everything Gaudí designed, only identifiable as Modernisme or Art Nouveau in the broadest sense. The ground floor, in particular, is rather astonishing with tracery, irregular oval windows and flowing sculpted stone work.
It seems that the goal of the designer was to avoid straight lines completely. Much of the façade is decorated with a mosaic made of broken ceramic tiles (trencadís) that starts in shades of golden orange moving into greenish blues. The roof is arched and was likened to the back of a dragon or dinosaur. A common theory about the building is that the rounded feature to the left of centre, terminating at the top in a turret and cross, represents the lance of Saint George (patron saint of Catalonia, Gaudí\'s home), which has been plunged into the back of the dragon.
### Loft
The loft is considered to be one of the most unusual spaces. It was formerly a service area for the tenants of the different apartments in the building which contained laundry rooms and storage areas. It is known for its simplicity of shapes and its Mediterranean influence through the use of white on the walls. It contains a series of sixty catenary arches that creates a space which represents the ribcage of an animal. Some people believe that the "ribcage" design of the arches is a ribcage for the dragon\'s spine that is represented in the roof.
### The Atrium (light well) {#the_atrium_light_well}
The Atrium or the light well is in the central part of the house and delivers air and lighting to all corners of the house. Gaudí had an obsession with light and how it reflected off certain surfaces. The wall of the atrium has different tones of blue as well as a diamond textile pattern all around the walls. The blue tiles allow an equal distribution of light to all the floors. The well has windows with wooden splits to allow them to be open and closed for ventilation. Gaudí wanted to make the bottom of the well feel like the bottom of the sea. The skylight allows light to come in and reflect off the ceramic tiles into the windows to naturally illuminate the house. The blue tiles are more intensely colored at the top and get opaquer towards the bottom. The diamond textiles match the rest of the house\'s use of different, functional shapes.
### Noble floor and museum {#noble_floor_and_museum}
The noble floor is larger than seven-hundred square meters. It is the main floor of the building. The noble floor is accessed through a private entrance hall that uses skylights resembling tortoise shells and vaulted walls in curving shapes. On the noble floor there is a spacious landing with direct views of the blue tiling of the building well. On the Passeig de Gracia side is Batlló\'s study, a dining room, and a secluded spot for courting couples, decorated with a mushroom-shaped fireplace. The elaborate and animal-like décor continues throughout the whole noble floor.
In 2002, as part of the celebration of the International Year of Gaudí, the house opened its doors to the public and people were allowed to visit the noble floor. Casa Batlló met with great unanticipated success, and visitors became eager to see the rest of the house. Two years later, in celebration of the one hundredth anniversary of the beginning of work on Casa Batlló, the fifth floor was restored and the house extended its visit to the loft and the well. In 2005, Casa Batlló became a UNESCO World Heritage Site.
### Roof
The roof terrace is one of the most popular features of the entire house due to its famous dragon back design. Gaudí represents an animal\'s spine by using tiles of different colors on one side. The roof is decorated with four chimney stacks designed to prevent backdraughts.
### Exterior façade {#exterior_façade}
The façade has three distinct sections which are harmoniously integrated. The lower ground floor with the main floor and two first-floor galleries are contained in a structure of Montjuïc sandstone with undulating lines. The central part, which reaches the last floor, is a multicolored section with protruding balconies. The top of the building is a crown, like a huge gable, which is at the same level as the roof and helps to conceal the room where there used to be water tanks. This room is currently empty. The top displays a trim with ceramic pieces that has attracted multiple interpretations.
#### Roof tile {#roof_tile}
The roof\'s arched profile recalls the spine of a dragon with ceramic tiles for scales, and a small triangular window towards the right of the structure simulates the eye. Legend has it that it was once possible to see the Sagrada Família through this window, which was being built simultaneously. As of 2022, the partial view of the Sagrada Família is available from this vantage point, with its spires visible over newer buildings. The tiles were given a metallic sheen to simulate the varying scales of the monster, with the color grading from green on the right side, where the head begins, to deep blue and violet in the center, to red and pink on the left side of the building.
#### Tower and bulb {#tower_and_bulb}
One of the highlights of the façade is a tower topped with a cross of four arms oriented to the cardinal directions. It is a bulbous, root-like structure that evokes plant life. There is a second bulb-shaped structure similarly reminiscent of a thalamus flower, which is represented by a cross with arms that are actually buds announcing the next flowering. The tower is decorated with monograms of Jesus (JHS), Maria (M with the ducal crown) and Joseph (JHP), made of ceramic pieces that stand out golden on the green background that covers the façade. These symbols show the deep religiosity of Gaudí, who was inspired by the contemporaneous construction of his basilica to choose the theme of the holy family.
The bulb was broken when it was delivered, perhaps during transportation. Although the manufacturer committed to re-do the broken parts, Gaudí liked the aesthetic of the broken masonry and asked that the pieces be stuck to the main structure with lime mortar and held in with a brass ring.
#### Central section {#central_section}
The central part of the façade evokes the surface of a lake with water lilies, reminiscent of Monet\'s *Nymphéas*, with gentle ripples and reflections caused by the glass and ceramic mosaic. It is a great undulating surface covered with plaster fragments of colored glass discs combined with 330 rounds of polychrome pottery. The discs were designed by Gaudí and Jujol between tests during their stay in Majorca, while working on the restoration of the Cathedral of Palma.
#### Balcony
Finally, above the central part of the façade is a smaller balcony, also iron, with a different exterior aesthetic, closer to a local type of lily. Two iron arms were installed here to support a pulley to raise and lower furniture.
#### Main floor {#main_floor}
The façade of the main floor, made entirely in sandstone, and is supported by two columns. The design is complemented by joinery windows set with multicolored stained glass. In front of the large windows, as if they were pillars that support the complex stone structure, there are six fine columns that seem to simulate the bones of a limb, with an apparent central articulation; in fact, this is a floral decoration. The rounded shapes of the gaps and the lip-like edges carved into the stone surrounding them create a semblance of a fully open mouth, for which the Casa Batlló has been nicknamed the \"house of yawns\". The structure repeats on the first floor and in the design of two windows at the ends forming galleries, but on the large central window there are two balconies as described above.
## Gallery
<File:CasaBatlló> NobleFloor saloon stainedglass.jpg\|Stained glass noblefloor of Casa Batlló <File:CasaBatlló> NobleFloor saloon side.jpg\|Noblefloor of Casa Batlló <File:CasaBatllo> rooftop chimneys dragon.jpg\|Chimneys of Casa Batlló <File:CasaBatllo> rooftop chimneys.jpg\|Rooftop of Casa Batlló <File:CasaBatllo> inner courtyard bottom.jpg\|Inner lightwell of Casa Batlló <File:CasaBatllo> inner courtyard.jpg\|Blue lightwell of Casa Batlló <File:CasaBatllo> attic arcs.jpg\|Catenary arcs of Casa Batlló <File:CasaBatllo> back dragon roof.jpg\|Dragon roof of Casa Batlló <File:CasaBatllo> dragon stairs.jpg\|Dragon stairs of Casa Batlló <File:CasaBatllo> NobleFloor saloon.jpg\|Saloon noble floor of Casa Batlló <File:Facade> of Casa Batlló - 2013.07 - panoramio.jpg\|Façade of Casa Batlló <File:Close> up Casa Batlo.JPG\|Façade close-up <File:Casa> batllo chimney.jpg\|Close-up of a chimney <File:Casa> Batlló Fireplace.jpg\|Casa Batlló fireplace <File:Casa> Batlló Light Well.jpg\|Casa Batlló central light well <File:Casa> Batlló - Barcelona.jpg\|Casa Batlló - Night View <File:Casa> Batlló (Antoni Gaudi) (atrium), 43, Passeig de Gràcia, Eixample, Barcelona, Catalonia, Spain.jpg\|Atrium of Casa Batlló <File:Casa> Batlló (Antoni Gaudi) (interior, ceiling close up), 43, Passeig de Gràcia, Eixample, Barcelona, Catalonia, Spain.jpg\|Ceiling close-up <File:Casa> Batlló (Antoni Gaudi) (interior, stained-glass window close up), 43, Passeig de Gràcia, Eixample, Barcelona, Catalonia, Spain.jpg\|Stained-glass window close-up <File:Casa> Batlló chair.JPG\|Chair in oak, designed 1906 <File:Gaudi-prie-dieu.jpg%7CPrie> Dieu, or prayer desk, designed 1906 <File:Casa> Batlló - Night View with Flowers.jpg\|Casa Batlló - Night View with Flowers <File:Casa> Batlló - Night View Corner.jpg\|Casa Batlló - Night View Corner <File:Casa> Batlló light show.png\|Casa Batlló night view with blue lights
| 2025-08-01T00:00:00 |
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