92-513: Rampasasa pygmies is a name given to a group of families described as pygmoid or Negrito , native to Waemulu village in Kecamatan Wae Rii , Manggarai Regency , Flores , Indonesia , following the discovery of Homo floresiensis in the nearby Liang Bua cave in 2003. The Rampasasa have since been reported as claiming Homo floresiensis as their ancestor and as "cashing in on hobbit craze". A genetic study published in 2018 discounted
184-509: A platypus myth and another, The Dinderi and Gujum - The Legend of the Stones of the Mary River . Susan McIntyre-Tamwoy, archaeologist and adjunct professor at James Cook University , has written of the northern Cape York Aboriginal people's belief of the bipotaim , which is when "the landscape as we know it today was created". Bipotaim was formed "before people, although not perhaps before
276-483: A boundary of 190 nm between hard and soft UV regions. Very hot objects emit UV radiation (see black-body radiation ). The Sun emits ultraviolet radiation at all wavelengths, including the extreme ultraviolet where it crosses into X-rays at 10 nm. Extremely hot stars (such as O- and B-type) emit proportionally more UV radiation than the Sun. Sunlight in space at the top of Earth's atmosphere (see solar constant )
368-433: A deep-bluish-purple Wood's glass optical filter that blocks almost all visible light with wavelengths longer than 400 nanometers. The purple glow given off by these tubes is not the ultraviolet itself, but visible purple light from mercury's 404 nm spectral line which escapes being filtered out by the coating. Other black lights use plain glass instead of the more expensive Wood's glass, so they appear light-blue to
460-712: A dozen pygmy groups, sometimes unrelated to each other. The best known are the Mbenga (Aka and Baka) of the western Congo Basin , who speak Bantu and Ubangian languages ; the Mbuti (Efe etc. ) of the Ituri Rainforest , who speak Bantu and Central Sudanic languages , and the Twa of the African Great Lakes , who speak Bantu Rundi and Kiga . Most pygmy communities are partially hunter-gatherers, living partially but not exclusively on
552-671: A filter coating which absorbs most visible light. Halogen lamps with fused quartz envelopes are used as inexpensive UV light sources in the near UV range, from 400 to 300 nm, in some scientific instruments. Due to its black-body spectrum a filament light bulb is a very inefficient ultraviolet source, emitting only a fraction of a percent of its energy as UV. Specialized UV gas-discharge lamps containing different gases produce UV radiation at particular spectral lines for scientific purposes. Argon and deuterium arc lamps are often used as stable sources, either windowless or with various windows such as magnesium fluoride . These are often
644-574: A measure of length corresponding to the distance from the elbow to the first knuckle of the middle finger, meant to express pygmies' diminutive stature. In Greek mythology and classical natural history , the word denoted a tribe of diminutive people first described by the ancient Greek poet Homer , and reputed to live to the south of modern-day Ethiopia or in India. For example, Aristotle described them thus in his History of Animals (while discussing cranes that migrate south of Egypt): "The story
736-683: A member of the Jinibara (the Dalla people ) tribe of SE Queensland, Gaiarbau, who was born in 1873 and had lived for many years traditionally with his tribe, said that he knew of the "existence of these "little people – the Dinderi", also known as "Dimbilum", "Danagalalangur" and "Kandju". Gaiarbau claims he saw members of a "tribe of small people ... and said they were like dwarfs ... and ... not ... any of them stood five feet [1.5m]." The Dinderi are also recorded in other stories, such as one concerning
828-545: A number of ranges recommended by the ISO standard ISO 21348: Several solid-state and vacuum devices have been explored for use in different parts of the UV spectrum. Many approaches seek to adapt visible light-sensing devices, but these can suffer from unwanted response to visible light and various instabilities. Ultraviolet can be detected by suitable photodiodes and photocathodes , which can be tailored to be sensitive to different parts of
920-438: A result of island syndrome which, amongst other things, results in reduced body size in insular humans. Ultraviolet Ultraviolet radiation , also known as simply UV , is electromagnetic radiation of wavelengths of 10–400 nanometers , shorter than that of visible light , but longer than X-rays . UV radiation is present in sunlight , and constitutes about 10% of the total electromagnetic radiation output from
1012-409: A thousand people were killed in the first eight months of 2014 alone with the number of displaced people estimated to be 650,000 as of December 2017. The weapons used in the conflict are often arrows and axes, rather than guns. Historically, the pygmy have always been viewed as inferior by both colonial authorities and the village-dwelling Bantu tribes. Pygmy children were sometimes captured during
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#17330853273991104-463: A threat to political co-operation among them. This and other publications promoting the trihybrid model drew several responses, which went over the current scientific evidence against the theory, and suggested that attempts to revive the theory were motivated by an agenda of undermining Aboriginal and Torres Strait Islander claims to native title . Some Aboriginal oral histories and oral traditions from Queensland tell of "little red men". In 1957
1196-520: A typical efficiency of approximately 30–40%, meaning that for every 100 watts of electricity consumed by the lamp, they will produce approximately 30–40 watts of total UV output. They also emit bluish-white visible light, due to mercury's other spectral lines. These "germicidal" lamps are used extensively for disinfection of surfaces in laboratories and food-processing industries, and for disinfecting water supplies. 'Black light' incandescent lamps are also made from an incandescent light bulb with
1288-449: A variety of wavelength bands into the vacuum ultraviolet. Light-emitting diodes (LEDs) can be manufactured to emit radiation in the ultraviolet range. In 2019, following significant advances over the preceding five years, UVA LEDs of 365 nm and longer wavelength were available, with efficiencies of 50% at 1.0 W output. Currently, the most common types of UV LEDs are in 395 nm and 365 nm wavelengths, both of which are in
1380-1048: Is about 126 nm, characteristic of the Ar 2 * excimer laser. Direct UV-emitting laser diodes are available at 375 nm. UV diode-pumped solid state lasers have been demonstrated using cerium - doped lithium strontium aluminum fluoride crystals (Ce:LiSAF), a process developed in the 1990s at Lawrence Livermore National Laboratory . Wavelengths shorter than 325 nm are commercially generated in diode-pumped solid-state lasers . Ultraviolet lasers can also be made by applying frequency conversion to lower-frequency lasers. Ultraviolet lasers have applications in industry ( laser engraving ), medicine ( dermatology , and keratectomy ), chemistry ( MALDI ), free-air secure communications , computing ( optical storage ), and manufacture of integrated circuits. The vacuum ultraviolet (V‑UV) band (100–200 nm) can be generated by non-linear 4 wave mixing in gases by sum or difference frequency mixing of 2 or more longer wavelength lasers. The generation
1472-587: Is also responsible for the formation of vitamin D in most land vertebrates , including humans. The UV spectrum, thus, has effects both beneficial and detrimental to life. The lower wavelength limit of the visible spectrum is conventionally taken as 400 nm, so ultraviolet rays are not visible to humans , although people can sometimes perceive light at shorter wavelengths than this. Insects, birds, and some mammals can see near-UV (NUV), i.e., slightly shorter wavelengths than what humans can see. Ultraviolet rays are usually invisible to most humans. The lens of
1564-500: Is clearly subordinate, and ... the preponderant element is Murrayian." This trihybrid model is generally considered defunct today; craniometric, genetic, and linguistic evidence does not support a separate origin of Barrinean or other Aboriginal groups, and physical differences between Aboriginal groups can be explained by adaptation to differing environments. In 2002, the purported existence of short-statured people in Queensland
1656-412: Is composed of about 50% infrared light, 40% visible light, and 10% ultraviolet light, for a total intensity of about 1400 W/m in vacuum. The atmosphere blocks about 77% of the Sun's UV, when the Sun is highest in the sky (at zenith), with absorption increasing at shorter UV wavelengths. At ground level with the sun at zenith, sunlight is 44% visible light, 3% ultraviolet, and the remainder infrared. Of
1748-448: Is generally done in gasses (e.g. krypton, hydrogen which are two-photon resonant near 193 nm) or metal vapors (e.g. magnesium). By making one of the lasers tunable, the V‑UV can be tuned. If one of the lasers is resonant with a transition in the gas or vapor then the V‑UV production is intensified. However, resonances also generate wavelength dispersion, and thus the phase matching can limit
1840-497: Is in direct proportion to the degree of bright sunlight the body receives. Serotonin is thought to provide sensations of happiness, well-being and serenity to human beings. UV rays also treat certain skin conditions. Modern phototherapy has been used to successfully treat psoriasis , eczema , jaundice , vitiligo , atopic dermatitis , and localized scleroderma . In addition, UV radiation, in particular UVB radiation, has been shown to induce cell cycle arrest in keratinocytes ,
1932-649: Is no anthropological evidence linking pygmies to other islands of Vanuatu. The extinct archaic human species Homo luzonensis has been classified as a pygmy group. The remains used to identify Homo luzonensis were discovered in Luzon , the Philippines , in 2007, and were designated as a species in 2019. Homo floresiensis , another archaic human from the island of Flores in Indonesia , stood around 1.1 metres (3 feet 7 inches) tall. The pygmy phenotype evolved as
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#17330853273992024-419: Is no doubt that a little sunlight is good for you! But 5–15 minutes of casual sun exposure of hands, face and arms two to three times a week during the summer months is sufficient to keep your vitamin D levels high. Vitamin D can also be obtained from food and supplementation. Excess sun exposure produces harmful effects, however. Vitamin D promotes the creation of serotonin . The production of serotonin
2116-421: Is not Bantu, and a similar percentage of Baka language is not Ubangian. Much of pygmy vocabulary is botanical, dealing with honey collecting, or is otherwise specialized for the forest and is shared between the two western pygmy groups. It has been proposed that this is the remnant of an independent western pygmy (Mbenga or "Baaka") language. However, this type of vocabulary is subject to widespread borrowing among
2208-513: Is not emitted by the laser, but rather by electron transitions in an extremely hot tin or xenon plasma, which is excited by an excimer laser. This technique does not require a synchrotron, yet can produce UV at the edge of the X‑ray spectrum. Synchrotron light sources can also produce all wavelengths of UV, including those at the boundary of the UV and X‑ray spectra at 10 nm. The impact of ultraviolet radiation on human health has implications for
2300-577: Is not fabulous, but there is in reality a race of dwarfish men, and the horses are little in proportion, and the men live in caves underground." Many African pygmies prefer to be identified by their ethnicity, such as the Aka (Mbenga), Baka , Mbuti , and Twa . The term Bayaka , the plural form of the Aka/Yaka, is sometimes used in the Central African Republic to refer to all local pygmies. Likewise,
2392-498: Is planned to be used to calibrate the color cameras for the 2019 ESA Mars rover mission, since they will remain unfaded by the high level of UV present at the surface of Mars. Common soda–lime glass , such as window glass, is partially transparent to UVA, but is opaque to shorter wavelengths, passing about 90% of the light above 350 nm, but blocking over 90% of the light below 300 nm. A study found that car windows allow 3–4% of ambient UV to pass through, especially if
2484-403: Is unusually short. The term pygmyism is used to describe the phenotype of endemic short stature (as opposed to disproportionate dwarfism occurring in isolated cases in a population) for populations in which adult men are on average less than 150 cm (4 ft 11 in) tall. Although the term is sometimes considered derogatory because it focuses on a physical trait, it remains
2576-446: Is visible to insects, some mammals, and some birds . Birds have a fourth color receptor for ultraviolet rays; this, coupled with eye structures that transmit more UV gives smaller birds "true" UV vision. "Ultraviolet" means "beyond violet" (from Latin ultra , "beyond"), violet being the color of the highest frequencies of visible light . Ultraviolet has a higher frequency (thus a shorter wavelength) than violet light. UV radiation
2668-752: The Batak and Aeta of the Philippines, the Andamanese of the Andaman Islands , and the Semang of the Malay Peninsula ) are sometimes called pygmies (especially in older literature). Negritos share some common physical features with African pygmy populations, including short stature and dark skin . The name "Negrito", from the Spanish adjective meaning "small black person", was given by early explorers. The explorers who named
2760-653: The Kongo word Bambenga is used in Congo . In other parts of Africa, they are called Wochua or Achua . In French-speaking Africa, they are sometimes referred to adjectivally as autochthon ( autochtone ), meaning "native" or "indigenous". Various theories have been proposed to explain the short stature of pygmies. Some studies suggest that it could be related to adaptation to low ultraviolet light levels in rainforests . This might mean that relatively little vitamin D can be made in human skin, thereby limiting calcium uptake from
2852-537: The UV degradation (photo-oxidation) of a material. The absorbers can themselves degrade over time, so monitoring of absorber levels in weathered materials is necessary. In sunscreen , ingredients that absorb UVA/UVB rays, such as avobenzone , oxybenzone and octyl methoxycinnamate , are organic chemical absorbers or "blockers". They are contrasted with inorganic absorbers/"blockers" of UV radiation such as carbon black , titanium dioxide , and zinc oxide . For clothing,
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2944-583: The World Wildlife Fund , can involve heavily armed park rangers removing native pygmies off the land. However, some have argued that the most efficient conservation methods involve giving land rights to the land's indigenous inhabitants. This pattern of eviction has been seen in national parks in the Democratic Republic of the Congo , such as Kahuzi-Biéga National Park , where pygmy inhabitants often cut
3036-462: The ultraviolet protection factor (UPF) represents the ratio of sunburn -causing UV without and with the protection of the fabric, similar to sun protection factor (SPF) ratings for sunscreen . Standard summer fabrics have UPFs around 6, which means that about 20% of UV will pass through. Suspended nanoparticles in stained-glass prevent UV rays from causing chemical reactions that change image colors. A set of stained-glass color-reference chips
3128-627: The EUV spectrum is set by a prominent He spectral line at 30.4 nm. EUV is strongly absorbed by most known materials, but synthesizing multilayer optics that reflect up to about 50% of EUV radiation at normal incidence is possible. This technology was pioneered by the NIXT and MSSTA sounding rockets in the 1990s, and it has been used to make telescopes for solar imaging. See also the Extreme Ultraviolet Explorer satellite . Some sources use
3220-568: The Murrayans, centred in southeastern Australia; and the Barrineans. He argued that people related to Oceanic Negritos were the first arrivals, and had been absorbed or replaced over time by later incoming peoples; the present-day Barrineans retained the greatest proportion of ancestry from this original Negrito group, "[b]ut this is not to say that the Barrineans are Negritos ... the Negritic component
3312-593: The Negritos assumed the Andamanese they encountered were from Africa. This belief was, however, discarded by anthropologists who noted that apart from dark skin, peppercorn hair, and steatopygia , the Andamanese had little in common with any African population, including the African pygmies. Their superficial resemblance to some Africans and Melanesians is thought to be from living in a similar environment, or simply retentions of
3404-539: The Pygmies and neighboring peoples, and the "Baaka" language was only reconstructed to the 15th century. African Pygmy populations are genetically diverse and extremely divergent from all other human populations, suggesting they have an ancient indigenous lineage. Their uniparental markers represent the second-most ancient divergence, after those typically found in Khoisan peoples. Recent advances in genetics shed some light on
3496-637: The Pygmies' short stature did not start with their common ancestor but instead evolved independently in adapting to similar environments, which adds support that some sets of genes related to height were advantageous in Eastern Pygmy populations, but not in Western Pygmy populations. However, Roger Blench argues that the Pygmies are not descended from residual hunter-gatherer groups but rather are offshoots of larger neighboring ethnolinguistic groups that had adopted forest subsistence strategies. Blench notes
3588-431: The Sun, are absorbed by oxygen and generate the ozone in the ozone layer when single oxygen atoms produced by UV photolysis of dioxygen react with more dioxygen. The ozone layer is especially important in blocking most UVB and the remaining part of UVC not already blocked by ordinary oxygen in air. Ultraviolet absorbers are molecules used in organic materials ( polymers , paints , etc.) to absorb UV radiation to reduce
3680-653: The Sun. It is also produced by electric arcs , Cherenkov radiation , and specialized lights, such as mercury-vapor lamps , tanning lamps , and black lights . The photons of ultraviolet have greater energy than those of visible light, from about 3.1 to 12 electron volts , around the minimum energy required to ionize atoms . Although long-wavelength ultraviolet is not considered an ionizing radiation because its photons lack sufficient energy, it can induce chemical reactions and cause many substances to glow or fluoresce . Many practical applications, including chemical and biological effects, are derived from
3772-562: The UN of enslaving Mbutis to prospect for minerals and forage for forest food, with those returning empty handed being killed and eaten. In Northern Katanga Province starting in 2013, the Pygmy Batwa people, whom the Luba people often exploit and allegedly enslave, rose up into militias, such as the "Perci" militia, and attacked Luba villages. A Luba militia known as "Elements" counterattacked. More than
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3864-557: The UV spectrum. Sensitive UV photomultipliers are available. Spectrometers and radiometers are made for measurement of UV radiation. Silicon detectors are used across the spectrum. Vacuum UV, or VUV, wavelengths (shorter than 200 nm) are strongly absorbed by molecular oxygen in the air, though the longer wavelengths around 150–200 nm can propagate through nitrogen . Scientific instruments can, therefore, use this spectral range by operating in an oxygen-free atmosphere (pure nitrogen, or argon for shorter wavelengths), without
3956-674: The UV was greater than 380 nm. Other types of car windows can reduce transmission of UV that is greater than 335 nm. Fused quartz , depending on quality, can be transparent even to vacuum UV wavelengths. Crystalline quartz and some crystals such as CaF 2 and MgF 2 transmit well down to 150 nm or 160 nm wavelengths. Wood's glass is a deep violet-blue barium-sodium silicate glass with about 9% nickel(II) oxide developed during World War I to block visible light for covert communications. It allows both infrared daylight and ultraviolet night-time communications by being transparent between 320 nm and 400 nm and also
4048-873: The UVA spectrum. The rated wavelength is the peak wavelength that the LEDs put out, but light at both higher and lower wavelengths are present. The cheaper and more common 395 nm UV LEDs are much closer to the visible spectrum, and give off a purple color. Other UV LEDs deeper into the spectrum do not emit as much visible light. LEDs are used for applications such as UV curing applications, charging glow-in-the-dark objects such as paintings or toys, and lights for detecting counterfeit money and bodily fluids. UV LEDs are also used in digital print applications and inert UV curing environments. Power densities approaching 3 W/cm (30 kW/m ) are now possible, and this, coupled with recent developments by photo-initiator and resin formulators, makes
4140-481: The UVC band at 253.7 nm and 185 nm due to the mercury within the lamp, as well as some visible light. From 85% to 90% of the UV produced by these lamps is at 253.7 nm, whereas only 5–10% is at 185 nm. The fused quartz tube passes the 253.7 nm radiation but blocks the 185 nm wavelength. Such tubes have two or three times the UVC power of a regular fluorescent lamp tube. These low-pressure lamps have
4232-556: The ancestors of African Pygmies most likely took place before 130,000 years ago, and certainly before 60,000 years ago. A commonly held belief is that African Pygmies are the direct descendants of Late Stone Age hunter-gatherer peoples of the central African rainforest, who were partially absorbed or displaced by later immigration of agricultural peoples, and adopted their Central Sudanic , Ubangian , and Bantu languages. This view has no archaeological support and ambiguous support from genetics and linguistics. Some 30% of Aka language
4324-581: The beginning of the UVB band at 315 nm, and rapidly increasing to 300 nm. The skin and eyes are most sensitive to damage by UV at 265–275 nm, which is in the lower UVC band. At still shorter wavelengths of UV, damage continues to happen, but the overt effects are not as great with so little penetrating the atmosphere. The WHO -standard ultraviolet index is a widely publicized measurement of total strength of UV wavelengths that cause sunburn on human skin, by weighting UV exposure for action spectrum effects at
4416-555: The closest proximity to Fiji would most likely be found in Vanuatu. In 2008, the remains of at least 25 miniature humans, who lived between 1,000 and 3,000 years ago, were found on the islands of Palau in Micronesia. During the 1900s, when Vanuatu was known as New Hebrides , sizable pygmy tribes were first reported throughout northeastern Santo . It is likely that they are not limited to this region of New Hebrides. Nonetheless, there
4508-403: The colored glow that many substances give off when exposed to UV light. UVA / UVB emitting bulbs are also sold for other special purposes, such as tanning lamps and reptile-husbandry. Shortwave UV lamps are made using a fluorescent lamp tube with no phosphor coating, composed of fused quartz or vycor , since ordinary glass absorbs UVC. These lamps emit ultraviolet light with two peaks in
4600-526: The development of solar-blind devices has been an important area of research. Wide-gap solid-state devices or vacuum devices with high-cutoff photocathodes can be attractive compared to silicon diodes. Extreme UV (EUV or sometimes XUV) is characterized by a transition in the physics of interaction with matter. Wavelengths longer than about 30 nm interact mainly with the outer valence electrons of atoms, while wavelengths shorter than that interact mainly with inner-shell electrons and nuclei. The long end of
4692-438: The diet for bone growth and maintenance and leading to the evolution of the small skeletal size. Other explanations include lack of food in the rainforest environment, low calcium levels in the soil, the need to move through dense jungle, adaptation to heat and humidity, and as an association with rapid reproductive maturation under conditions of early mortality. Other evidence points towards unusually low levels of expression of
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#17330853273994784-577: The distinction of "hard UV" and "soft UV". For instance, in the case of astrophysics , the boundary may be at the Lyman limit (wavelength 91.2 nm, the energy needed to ionise a hydrogen atom from its ground state), with "hard UV" being more energetic; the same terms may also be used in other fields, such as cosmetology , optoelectronic , etc. The numerical values of the boundary between hard/soft, even within similar scientific fields, do not necessarily coincide; for example, one applied-physics publication used
4876-463: The emitting sources in UV spectroscopy equipment for chemical analysis. Other UV sources with more continuous emission spectra include xenon arc lamps (commonly used as sunlight simulators), deuterium arc lamps , mercury-xenon arc lamps , and metal-halide arc lamps . The excimer lamp , a UV source developed in the early 2000s, is seeing increasing use in scientific fields. It has the advantages of high-intensity, high efficiency, and operation at
4968-575: The entire UV range. The nitrogen gas laser uses electronic excitation of nitrogen molecules to emit a beam that is mostly UV. The strongest ultraviolet lines are at 337.1 nm and 357.6 nm in wavelength. Another type of high-power gas lasers are excimer lasers . They are widely used lasers emitting in ultraviolet and vacuum ultraviolet wavelength ranges. Presently, UV argon-fluoride excimer lasers operating at 193 nm are routinely used in integrated circuit production by photolithography . The current wavelength limit of production of coherent UV
5060-482: The expansion of LED cured UV materials likely. UVC LEDs are developing rapidly, but may require testing to verify effective disinfection. Citations for large-area disinfection are for non-LED UV sources known as germicidal lamps . Also, they are used as line sources to replace deuterium lamps in liquid chromatography instruments. Gas lasers , laser diodes , and solid-state lasers can be manufactured to emit ultraviolet rays, and lasers are available that cover
5152-582: The eye when operating. Incandescent black lights are also produced, using a filter coating on the envelope of an incandescent bulb that absorbs visible light ( see section below ). These are cheaper but very inefficient, emitting only a small fraction of a percent of their power as UV. Mercury-vapor black lights in ratings up to 1 kW with UV-emitting phosphor and an envelope of Wood's glass are used for theatrical and concert displays. Black lights are used in applications in which extraneous visible light must be minimized; mainly to observe fluorescence ,
5244-600: The founder populations of modern humans. Frank Kingdon-Ward in the early 20th century reported a tribe of pygmy Tibeto-Burman speakers known as the Taron inhabiting the remote region of Mt. Hkakabo Razi in Southeast Asia on the border of China ( Yunnan and Tibet ), Burma, and India. A Burmese survey done in the 1960s reported a mean height of an adult male Taron at 1.43 metres (4 feet 8 inches) and that of females at 1.40 metres (4 feet 7 inches). These are
5336-518: The genes encoding the growth hormone receptor and growth hormone compared to the related tribal groups, associated with low serum levels of insulin-like growth factor 1 and short stature. African Pygmies live in several ethnic groups in Rwanda, Burundi, Uganda, Democratic Republic of the Congo, Republic of the Congo (ROC), Central African Republic, Cameroon, Equatorial Guinea, Gabon, Angola, Botswana, Namibia, Madagascar, and Zambia. There are at least
5428-542: The genocide. From the end of 2002 through January 2003 around 60,000 Pygmy civilians and 10,000 combatants were killed and often cannibalized in an extermination campaign known as " Effacer le tableau " during the Second Congo War . Human rights activists have made demands for the massacre to be recognized as genocide . In a strategy described as fortress conservation , the conservation efforts of national parks, often financed by international organizations such as
5520-544: The ground right into early summer and sun positions even at zenith are low, are particularly at risk. Skin, the circadian system, and the immune system can also be affected. The differential effects of various wavelengths of light on the human cornea and skin are sometimes called the "erythemal action spectrum". The action spectrum shows that UVA does not cause immediate reaction, but rather UV begins to cause photokeratitis and skin redness (with lighter skinned individuals being more sensitive) at wavelengths starting near
5612-516: The human eye blocks most radiation in the wavelength range of 300–400 nm; shorter wavelengths are blocked by the cornea . Humans also lack color receptor adaptations for ultraviolet rays. Nevertheless, the photoreceptors of the retina are sensitive to near-UV, and people lacking a lens (a condition known as aphakia ) perceive near-UV as whitish-blue or whitish-violet. Under some conditions, children and young adults can see ultraviolet down to wavelengths around 310 nm. Near-UV radiation
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#17330853273995704-658: The indigenous Wiradjuri nation employed by the Australian National Museum, there is no known archaeological or biological evidence such a people existed. Sentance claims it is a myth used to justify the colonisation of Australia as well as other countries by Europeans. Norman Gabel mentions that rumours exist of pygmy people in the interior mountains of Viti Levu in Fiji , but explains he had no evidence of their existence as of 2012. E. W. Gifford reiterated Gabel's statement in 2014 and claims that tribes of pygmies in
5796-547: The initial human form. Their origin and the route of their migration to Asia is a matter of great speculation. They are genetically distant from Africans and have been shown to have separated early from Asians, suggesting that they are either surviving descendants of settlers from the early out-of-Africa migration of the Great Coastal Migration of the Proto-Australoids , or that they are descendants of one of
5888-607: The lack of clear linguistic and archaeological evidence for the antiquity of pygmy cultures and peoples and also notes that the genetic evidence can be problematic. Blench also notes that there is no evidence of the Pygmies have hunting technology distinctive from that of their neighbors, and argues that the short stature of pygmy populations can arise relatively quickly (in less than a few millennia) due to strong selection pressures. The African Pygmies are particularly known for their usually vocal music, usually characterised by dense contrapuntal communal improvisation. Simha Arom says that
5980-408: The lack of suitable gas / vapor cell window materials above the lithium fluoride cut-off wavelength limit the tuning range to longer than about 110 nm. Tunable V‑UV wavelengths down to 75 nm was achieved using window-free configurations. Lasers have been used to indirectly generate non-coherent extreme UV (E‑UV) radiation at 13.5 nm for extreme ultraviolet lithography . The E‑UV
6072-591: The level of polyphonic complexity of pygmy music was reached in Europe in the 14th century, yet Pygmy culture is unwritten and ancient. Music permeates daily life and there are songs for entertainment as well as specific events and activities. The pygmy population was a target of the Interahamwe during the 1994 Rwandan genocide . Of the 30,000 Pygmies in Rwanda, an estimated 10,000 were killed and another 10,000 were displaced. They have been described as "forgotten victims" of
6164-419: The longer infrared and just-barely-visible red wavelengths. Its maximum UV transmission is at 365 nm, one of the wavelengths of mercury lamps . A black light lamp emits long-wave UVA radiation and little visible light. Fluorescent black light lamps work similarly to other fluorescent lamps , but use a phosphor on the inner tube surface which emits UVA radiation instead of visible light. Some lamps use
6256-595: The master's whim: in cigarettes, used clothing, or even nothing at all." As a result of pressure from UNICEF and human-rights activists, in 2009, a law that would grant special protections to the Pygmy people was awaiting a vote by the Congo parliament. According to reports made in 2013, this law was never passed. In the Democratic Republic of the Congo, during the Ituri conflict , Ugandan-backed rebel groups were accused by
6348-473: The most common type of skin cell. As such, sunlight therapy can be a candidate for treatment of conditions such as psoriasis and exfoliative cheilitis , conditions in which skin cells divide more rapidly than usual or necessary. In humans, excessive exposure to UV radiation can result in acute and chronic harmful effects on the eye's dioptric system and retina . The risk is elevated at high altitudes and people living in high latitude areas where snow covers
6440-483: The need for costly vacuum chambers. Significant examples include 193-nm photolithography equipment (for semiconductor manufacturing ) and circular dichroism spectrometers. Technology for VUV instrumentation was largely driven by solar astronomy for many decades. While optics can be used to remove unwanted visible light that contaminates the VUV, in general, detectors can be limited by their response to non-VUV radiation, and
6532-549: The only known "pygmies" of clearly East Asian descent. The cause of their diminutive size is unknown, but diet and endogamous marriage practices have been cited. The population of Taron pygmies has been steadily shrinking and is now down to only a few individuals. In 2013, a link between the Taron and the Derung people in Yunnan , China, was uncovered by Richard D. Fisher, which may indicate
6624-466: The origins of the various Pygmy groups. Researchers found "an early divergence of the ancestors of Pygmy hunter–gatherers and farming populations 60,000 years ago, followed by a split of the Pygmies' ancestors into the Western and Eastern pygmy groups 20,000 years ago." New evidence suggests East and West African Pygmy children have different growth patterns. The difference between the two groups may indicate
6716-721: The period of the Congo Free State , which exported Pygmy children to zoos throughout Europe, including the world's fair in the United States in 1907. Pygmies are often evicted from their land and given the lowest paying jobs. At a state level, Pygmies are sometimes not considered citizens and are refused identity cards, deeds to land, health care and proper schooling. The Lancet published a review showing that Pygmy populations often had worse access to health care than neighboring communities. Negritos in Southeast Asia (including
6808-506: The population, many Pygmies live as slaves to Bantu masters. The nation is deeply stratified between these two major ethnic groups. The Pygmy slaves belong to their Bantu masters from birth in a relationship that the Bantus call a time-honored tradition. A 2007 news report stated that even though Pygmies are responsible for much of the hunting, fishing and manual labor in jungle villages, "Pygmies and Bantus alike say that Pygmies are often paid at
6900-547: The possibility of the Rampasasa descending from H. floresiensis , concluding that "multiple independent instances of hominin insular dwarfism occurred on Flores". However, as no genetic material from H. floresiensis was included in the analyses, any truly definitive conclusions cannot be made. 8°32′S 120°27′E / 8.533°S 120.450°E / -8.533; 120.450 Pygmy In anthropology , pygmy peoples are ethnic groups whose average height
6992-540: The presence of pygmy populations among the Derung tribe. Australian anthropologist Norman Tindale and American anthropologist Joseph Birdsell suggested there were 12 Negrito-like tribes of short-statured Aboriginal peoples living on the coastal and rainforest areas around Cairns on the lands of the Mbabaram people and Djabugay people. Birdsell found that the average adult male height of Aboriginal people in this region
7084-454: The previous year at the other end of the visible spectrum. The simpler term "chemical rays" was adopted soon afterwards, and remained popular throughout the 19th century, although some said that this radiation was entirely different from light (notably John William Draper , who named them "tithonic rays" ). The terms "chemical rays" and "heat rays" were eventually dropped in favor of ultraviolet and infrared radiation , respectively. In 1878,
7176-828: The primary term associated with the African Pygmies , the hunter-gatherers of the Congo Basin (comprising the Bambenga , Bambuti and Batwa ). The terms "Asiatic pygmies" and "Oceanic pygmies" have also been used to describe the Negrito populations of Southeast Asia and Australo-Melanesian peoples of short stature. The Taron people of Myanmar are an exceptional case of a pygmy population of East Asian phenotype. The term pygmy , as used to refer to diminutive people, comes via Latin pygmaeus from Greek πυγμαῖος pygmaîos , derived from πυγμή pygmḗ , meaning "short cubit ", or
7268-502: The risks and benefits of sun exposure and is also implicated in issues such as fluorescent lamps and health . Getting too much sun exposure can be harmful, but in moderation, sun exposure is beneficial. UV (specifically, UVB) causes the body to produce vitamin D , which is essential for life. Humans need some UV radiation to maintain adequate vitamin D levels. According to the World Health Organization: There
7360-462: The same way as the visible blue light from those parts of the sky. UVB also plays a major role in plant development, as it affects most of the plant hormones. During total overcast, the amount of absorption due to clouds is heavily dependent on the thickness of the clouds and latitude, with no clear measurements correlating specific thickness and absorption of UVA and UVB. The shorter bands of UVC, as well as even more-energetic UV radiation produced by
7452-453: The short people [pygmies?]. Red devils occupy parts of the adjacent stony coast but our home is here in the sand dunes and forest. Before the Marakai ['white people'] came to our land the people were plentiful and they roamed the land. They understood the land and called out in the language of the country to seek permission, as they should ...". According to Nathan Sentance, a librarian from
7544-414: The short people or the red devils as these were also here before people". She writes, "many ethnographers recorded stories of 'short people' or what they referred to as 'pygmy tribes ' ", such as Lindsey Page Winterbotham . She used information collected both through oral accounts (including those of Injinoo people), observation and archival research. McIntyre-Tamwoy recounts a bipotaim story: "We are
7636-463: The skin to UV, along with an increased risk of skin cancer . The amount of UV radiation produced by the Sun means that the Earth would not be able to sustain life on dry land if most of that light were not filtered out by the atmosphere . More energetic, shorter-wavelength "extreme" UV below 121 nm ionizes air so strongly that it is absorbed before it reaches the ground. However, UV (specifically, UVB)
7728-586: The sterilizing effect of short-wavelength light by killing bacteria was discovered. By 1903, the most effective wavelengths were known to be around 250 nm. In 1960, the effect of ultraviolet radiation on DNA was established. The discovery of the ultraviolet radiation with wavelengths below 200 nm, named "vacuum ultraviolet" because it is strongly absorbed by the oxygen in air, was made in 1893 by German physicist Victor Schumann . The electromagnetic spectrum of ultraviolet radiation (UVR), defined most broadly as 10–400 nanometers, can be subdivided into
7820-706: The trees down to sell charcoal. In the Republic of the Congo , this is seen in the Messok Dja protected area. In Cameroon , this is seen in the Lobéké National Park . In Uganda , some Batwa have been removed from land reclassified as national parks, such as the Mgahinga Gorilla National Park , which is home to the endangered Mountain gorilla . In the Republic of the Congo, where Pygmies make up 2% of
7912-478: The tunable range of the 4 wave mixing. Difference frequency mixing (i.e., f 1 + f 2 − f 3 ) has an advantage over sum frequency mixing because the phase matching can provide greater tuning. In particular, difference frequency mixing two photons of an Ar F (193 nm) excimer laser with a tunable visible or near IR laser in hydrogen or krypton provides resonantly enhanced tunable V‑UV covering from 100 nm to 200 nm. Practically,
8004-500: The ultraviolet radiation that reaches the Earth's surface, more than 95% is the longer wavelengths of UVA, with the small remainder UVB. Almost no UVC reaches the Earth's surface. The fraction of UVA and UVB which remains in UV radiation after passing through the atmosphere is heavily dependent on cloud cover and atmospheric conditions. On "partly cloudy" days, patches of blue sky showing between clouds are also sources of (scattered) UVA and UVB, which are produced by Rayleigh scattering in
8096-417: The way that UV radiation can interact with organic molecules. These interactions can involve absorption or adjusting energy states in molecules, but do not necessarily involve heating. Short-wave ultraviolet light is ionizing radiation . Consequently, short-wave UV damages DNA and sterilizes surfaces with which it comes into contact. For humans, suntan and sunburn are familiar effects of exposure of
8188-457: The wild products of their environment. They trade with neighbouring farmers to acquire cultivated foods and other material items; no group lives deep in the forest without access to agricultural products. It is estimated that there are between 250,000 and 600,000 Pygmies living in the Congo rainforest . However, although Pygmies are thought of as forest people, the groups called Twa may live in open swamp or desert. Expansion to Central Africa by
8280-671: Was brought into the public eye by Keith Windschuttle and Tim Gillin in an article published by the right-wing Quadrant magazine (edited by Windschuttle himself). The authors argued that these people were evidence for a distinct Negrito population in support of Birdsell's theory, and claimed that "the fact that the Australian pygmies have been so thoroughly expunged from public memory suggests an indecent concurrence between scholarly and political interests", because evidence of descent from earlier or later waves of origin could lead to conflicting claims of priority by Aboriginal people and hence pose
8372-643: Was discovered in February 1801 when the German physicist Johann Wilhelm Ritter observed that invisible rays just beyond the violet end of the visible spectrum darkened silver chloride -soaked paper more quickly than violet light itself. He announced the discovery in a very brief letter to the Annalen der Physik and later called them "(de-)oxidizing rays" ( German : de-oxidierende Strahlen ) to emphasize chemical reactivity and to distinguish them from " heat rays ", discovered
8464-554: Was significantly less than that of other Aboriginal Australian groups; however, it was still greater than the maximum height for classification as a pygmy people, so the term pygmy may be considered a misnomer. He called this short-statured group Barrineans , after Lake Barrine . Birdsell classified Aboriginal Australians into three major groups, mixed together to varying degrees: the Carpentarians, best represented in Arnhem Land ;
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