title: Davinson Sánchez

text: At youth level, Sánchez represented Colombia at the 2013 South American U-17 Championship and was part of the Colombia squads that participated at the 2015 South American U-20 Championship and the 2015 FIFA U-20 World Cup, respectively. He made his senior debut for Colombia in 2016 and has represented the nation at two editions of the Copa América, and the 2018 FIFA World Cup.


title: Davinson Sánchez

text: As a youth, Sánchez played in the youth academy of América de Cali, but after his parents moved, he was transferred to Atlético Nacional, where he was educated under the wings of Juan Carlos Osorio. The defender made his debut for the senior team on 27 October 2013, in a 0–1 loss to Boyacá Chicó. Osorio put the player in the starting lineup and he completed the entire match.


title: Davinson Sánchez

text: On 2 March 2016, Sánchez scored his first goal for Nacional in a 3–0 victory over Sporting Cristal from Peru in the Copa Libertadores. Due to his performances for Nacional, foreign clubs including Barcelona, Flamengo, and Ajax showed an interest in signing the player. Barcelona made a formal offer to sign the player, but Sánchez declined the offer because he didn't want to start in FC Barcelona B, the reserve team. He won the Copa Libertadores 2016 against Ecuadorian Independiente del Valle.


title: Davinson Sánchez

text: In June 2016, Sánchez signed a five-year contract with Dutch side Ajax, until 2021. The club paid a transfer fee of €5 million to Atlético Nacional. A few days earlier, Ajax had signed Sánchez's compatriot Mateo Cassierra, thus making him the second Colombian in the squad. Sánchez joined his new team, after Nacional had finished its participation in the Copa Libertadores. Sánchez debuted with Ajax on 13 August in a 2–2 tie with Roda JC Kerkrade, he started and played the 90 minutes. His first goal with the club was on 24 September against PEC Zwolle. On 8 May 2017, he was named as best player of the season for Ajax.


title: Davinson Sánchez

text: On 18 August 2017, Premier League club Tottenham Hotspur announced that they had agreed a move for Sánchez signing a six-year contract subject to a work permit, for a reported transfer fee of up to £42 million. He made his debut on 27 August as a substitute for Mousa Dembélé in the 92nd minute in a 1–1 draw with Burnley.


title: Davinson Sánchez

text: On 10 February 2019, Sánchez scored his first goal for Tottenham in the Premier League game against Leicester City.


title: Davinson Sánchez

text: On 1 June 2019, Sánchez was an unused substitute for Tottenham in the 2019 Champions League Final against Liverpool.


title: Davinson Sánchez

text: On 11 February 2021, Sánchez scored twice, his first goals in two years, in the 2020–21 FA Cup fifth round match against Everton that eventually ended in a 5–4 loss for Tottenham after extra time.


title: Davinson Sánchez

text: In November 2011, Sánchez was called up to dispute the 2011 South American U-15 Championship, where his team finished as runner-up behind Brazil; Sánchez was appointed as his team's captain for the tournament.


title: Davinson Sánchez

text: Sánchez represented Colombia U-17 side at the 2013 South American U-17 Championship, where he appeared twice in the group stage.


title: Davinson Sánchez

text: On 6 January 2015, he was included in Carlos Restrepo's 23-man list for the 2015 South American U-20 Championship, where Colombia secured qualification to the 2015 FIFA U-20 World Cup and the Olympic play-off for Rio 2016 after finishing runner-up. On 6 May, Sánchez was named in Colombia final 23-man team for the U-20 World Cup, where his team exited the tournament in the round of 16 after falling to the United States.


title: Davinson Sánchez

text: Despite not disputing the Olympics, Sánchez appeared in both legs for the play-off series against the United States, in which Colombia qualified to the Olympics for the first team since Barcelona 1992 after finishing the series 3–2 on aggregate.


title: Davinson Sánchez

text: Colombia manager José Pékerman called up Sánchez for a training squad with the senior Colombia squad in February 2016. On 26 August 2022, he was named in Colombia's squad for the 2018 World Cup qualifiers against Venezuela and Brazil. On 19 November, Sánchez made his debut against Argentina.


title: Davinson Sánchez

text: In May 2018, he was named in Colombia's preliminary 35-man squad for the 2018 FIFA World Cup in Russia. In June 2018, he was named in Colombia's final 23-man squad for the 2018 FIFA World Cup in Russia. He played in all three group matches and their round of 16 match against England.


title: Davinson Sánchez

text: In June 2019, he started in three of the four games at the 2019 Copa América, helped the team keep a clean sheet and beat Argentina for the first time in 12 years. The team however lost in the quarter-final against Chile after a penalty shoot-out.


title: Davinson Sánchez

text: On 10 June 2021, Sánchez was included in Reinaldo Rueda's 23-man squad for the 2021 Copa América in Brazil. He featured in all of Colombia's matches as the team secured bronze after defeating Peru 3–2 for the third-place playoff.


title: Davinson Sánchez

text: On 19 November 2022, Sánchez scored his first international goal in a 2–0 friendly win against Paraguay.


title: Jellied eels

text: Jellied eels are a traditional English dish that originated in the 18th century, primarily in the East End of London. The dish consists of chopped eels boiled in a spiced stock that is allowed to cool and set, forming a jelly. It is usually served cold.


title: Jellied eels

text: Eels were historically a cheap, nutritious, and readily available food source for the people of London; European eels were once so common in the Thames that nets were set as far upriver as London itself, and eels became a staple for London's poor. The earliest known eel, pie and mash houses opened in London in the 18th century, and the oldest surviving shop, M Manze, has been open since 1902. At the end of the Second World War, there were around 100 eel, pie and mash houses in London. In 1995, there were 87.


title: Jellied eels

text: In the present day, there are relatively few eel, pie and mash shops still in existence, although jellied eels are sold in some of the capital's delicatessen shops and supermarkets. The water quality of the Thames, having improved greatly since the 1960s, has since become suitable once again for recolonisation by eels. The Environment Agency supports a Thames fishery, allowing nets as far upriver as Tower Bridge.


title: Jellied eels

text: Jellied eels are traditionally prepared using the European eels native to Britain. Typically, the eels are chopped (shucked) into rounds and boiled in water and vinegar to make a fish stock with nutmeg and lemon juice, before being allowed to cool. The eel is a naturally gelatinous fish, with the cooking process releasing proteins, like collagen, into the liquid, which solidify upon cooling to form a jelly, though gelatin may be added in order to aid this process.


title: Jellied eels

text: Recipes for jellied eels are individual to particular London pie and mash shops, and also street sellers; however, traditional recipes for authentic Victorian jellied eels all have common ingredients and cooking methods, with variation only in the choice of herbs and spices used to flavour the dish.


title: Jellied eels

text: Jellied eels are often sold with pie and mash, another traditional East End food, and eaten with chilli vinegar or with malt vinegar and white pepper.


title: Jellied eels

text: The dish is also consumed in other parts of Europe, including Denmark, Sweden, France, Germany, Poland, Belgium and the Netherlands.


title: Bulgarian alphabet

text: The Cyrillic alphabet was originally developed in the First Bulgarian Empire during the 9th – 10th century AD at the Preslav Literary School.


title: Bulgarian alphabet

text: It has been used in Bulgaria (with modifications and exclusion of certain archaic letters via spelling reforms) continuously since then, superseding the previously used Glagolitic alphabet, which was also invented and used there before the Cyrillic script overtook its use as a written script for the Bulgarian language. The Cyrillic alphabet was used in the then much bigger territory of Bulgaria (including most of today's Serbia), North Macedonia, Kosovo, Albania, Northern Greece (Macedonia region), Romania and Moldova, officially from 893. It was also transferred from Bulgaria and adopted by the East Slavic languages in Kievan Rus' and evolved into the Belarusian, Russian and Ukrainian alphabets and the alphabets of many other Slavic (and later non-Slavic) languages. Later, some Slavs modified it and added/excluded letters from it to better suit the needs of their own language varieties.


title: Bulgarian alphabet

text: In the 9th century, the Bulgarian Empire introduced the Glagolitic alphabet, devised by Saint Cyril and Saint Methodius. The Glagolitic alphabet was gradually superseded in later centuries by the Cyrillic script, developed around the Preslav Literary School, Bulgaria at the end of the 9th century.


title: Bulgarian alphabet

text: Several Cyrillic alphabets with 28 to 44 letters were used in the early and middle 19th century during the efforts on the codification of Modern Bulgarian until an alphabet with 32 letters, proposed by Marin Drinov, gained prominence in the 1870s: it was used until the orthographic reform of 1945, when the letters yat (uppercase , lowercase ) and yus (uppercase , lowercase ) were removed from its alphabet, reducing the number of letters to 30. Yat was also known as "double e" (), and yus was also known as "big nasal sign" (), crossed yer (), and "wide yer" (). Although Bulgarian uses the Cyrillic alphabet, some preferred letter shapes in Bulgaria are different to those in Russian use.


title: Bulgarian alphabet

text: With the accession of Bulgaria to the European Union on 1 January 2007, the Cyrillic script became the third official script of the European Union, following the Latin and Greek scripts.


title: Bulgarian alphabet

text: The following table gives the letters of the Bulgarian alphabet, along with the values for the sound of each letter. The listed transliteration in the Official transliteration column (known as the Streamlined System) is official in Bulgaria and is listed in the Official orthographic dictionary (2012). For other transliteration standards see Romanization of Bulgarian.


title: Bulgarian alphabet

text: Most letters in the Bulgarian alphabet stand for just one specific sound. Five letters stand for sounds written in English with two or more letters. These letters are (ch), (sh), (sht), (yu), and (ya). Two additional sounds are written with two letters: these are () and (). The letter marks the softening (palatalization) of any consonant (except , , and ) before the letter , while and after consonants mark the palatalization of the preceding consonant in addition to representing the vowels and .


title: Bulgarian alphabet

text: The names of most letters are simple representations of their phonetic values, with consonants being followed by – thus the alphabet goes: – – , etc. However, the name of the letter is "i-kratko" ("short i"), the name of is "er-golyam" ("large yer"), and the name of is "er-malak" ("small yer"). People often refer to simply as .


title: Bulgarian alphabet

text: The grave accent is used to distinguish the pronoun 'her' from the conjunction 'and'. Ѝ is not considered a separate letter but rather a special form of .


title: Bulgarian alphabet

text: Bulgarian is usually described as having a phonemic orthography, meaning that words are spelt the way they are pronounced. This is largely true, but there are exceptions. Three of the most cited examples are:


title: Bulgarian alphabet

text: Since the time of Bulgaria's liberation in the late 19th century, the Bulgarian language has taken on a large number of words from Western European languages. All of these are transcribed phonetically into Cyrillic, e.g.:


title: Bulgarian alphabet

text: In the years since the end of communism and the rise of technology, the tendency for borrowing has shifted mainly to English, where much computer-related terminology has entered and been inflected accordingly – again, in a wholly phonetic way. Examples include:


title: Bulgarian alphabet

text: The computer-related neologisms are often used interchangeably with traditional Bulgarian words, e.g. 'download' and 'upload' can be simply and ( and – 'to bring down' and 'to put up').


title: Bulgarian alphabet

text: The insertion of English words directly into a Cyrillic Bulgarian sentence, while frowned upon, has been increasingly used in the media. This is done for several reasons, including –


title: Bulgarian alphabet

text: Brand names are also often not transcribed: WikiLeaks, YouTube, Skype – as opposed to , , . However, this is not always the case, as in the headline "" (official transliteration: "Feysbuk vs. Gugal"). Note the inconsistency here – despite the insistence on Cyrillic, the "vs." has been retained in Roman script.


title: Bulgarian alphabet

text: The 2012 "Official Orthographic Dictionary of the Bulgarian Language" by the Bulgarian Academy of Sciences permits widely known proper names to remain in their original alphabet. Example sentences are given, all containing names of American IT companies: Yahoo, Microsoft, YouTube, PayPal, Facebook.


title: Loaded Weapon 1

text: National Lampoon's Loaded Weapon 1 (also known simply as Loaded Weapon 1) is a 1993 American parody film directed and co-written by Gene Quintano, and starring Emilio Estevez, Samuel L. Jackson, Kathy Ireland, Frank McRae, Tim Curry and William Shatner. The film mainly spoofs the first three "Lethal Weapon" films, as well as several others including "Basic Instinct", "Die Hard", "Dirty Harry", "Rambo", "The Silence of the Lambs", "Wayne's World", "48 Hrs." and TV series such as "CHiPs". "Loaded Weapon 1" was released on February 5, 1993.


title: Loaded Weapon 1

text: In Los Angeles, Billie York is murdered by a man known as Mr Jigsaw because she possesses a microfilm that can turn cocaine into cookies. Her former partner, Wes Luger, who is about to retire, is assigned the case by the reluctant captain Doyle, who dismisses it as a suicide but gives Luger the case. The catch is that Luger will have to be partnered with Jack Colt, a burned out cop who recently lost his dog, Claire. The two visit Harold Leacher, who tells them that Colt's former general in the Vietnam War, Mortars, is heading the operation. Meanwhile, Jigsaw and Mortars visit Mike McCraken, whom Jigsaw murders for losing the microfilm.


title: Loaded Weapon 1

text: After finding the body, Colt and Luger go to Rick Becker, who claims that he laundered money with York (the money actually being in the laundry machine), but Rick is shot multiple times by unknown assailants, forcing Colt and Luger to go to the Wilderness Girls factory. The head, Destiny Demeanor, claims no knowledge of the operation during the trial, but she is revealed to be working for Mortars and his gang. Colt meets Luger's family, but he runs away when they try to seduce him. Destiny and Colt hang out at Colt's house, while Mortars sends a helicopter to destroy Colt's house (a trailer that is actually a mansion inside), but they accidentally destroy John McClane's house.


title: Loaded Weapon 1

text: Due to lack of evidence, Doyle dismisses the case, but Colt still decides to stop the operation, much to the dismay of Luger. Luger is a by-the-book cop, after he took an unscheduled break from his crossing guard duties (as a child), which led to an old lady being run over by a car and killed. Colt breaks in and Destiny, now having fallen in love with Colt, attempts to stop Mortars, but Mortars shows that he was the one who kidnapped Claire, and shows him Rick and Claire chained to a wall (Rick actually having survived the incident). Mortars shoots Destiny, who clings to life long enough to confess her feelings for him. Colt manages to catch up with Mortars, but then Luger shows up, having considered what Colt said to him earlier. He shoots and kills Mortars, and Colt kills Jigsaw, but starts a fire that destroys the whole factory. Doyle shows up, and asks Luger to stay in the force. Luger agrees, but as long as Colt is his partner. In the end, Destiny, having survived, shows up with Rick and Claire, and the team dances to "Bohemian Rhapsody".


title: Loaded Weapon 1

text: "Loaded Weapon 1" opened at number 1 at the US box office and grossed almost $28 million in the United States and Canada in total. Internationally, it grossed $23.2 million for a worldwide total of $51.2 million. The movie, along with "Excessive Force" and "Three of Hearts", was cited for its contribution to New Line's record pre sales in 1992 totaling $91.2 million.


title: Loaded Weapon 1

text: The film received mainly negative reviews. Owen Gleiberman of "Entertainment Weekly" gave the film a C, comparing it negatively to the Zucker, Abrahams and Zucker films, while also noting that "the "Lethal Weapon" films, with their hyperbolic explosiveness, lurid repartee, and quasi-loco Mel Gibson hero, are already winking at the audience. (Last year's spoofy, ragtag "Lethal Weapon 3" practically turned its own slovenliness into a running gag.) The only way to make light of them is to exaggerate the cartoon funkiness that's already at the center of their appeal. It's no wonder this Weapon ends up shooting blanks." Lawrence


title: Loaded Weapon 1

text: Cohn of "Variety" opened his review by saying that the film is "more an imitation than a parody [and is a] would-be comedy [that] is very short on laughs" Roger Ebert of "The Chicago Sun-Times" said the film's main failure was that the "Lethal Weapon" movies already contained sly spoofs of the police film genre: "The send-up doesn't feel much different than the real thing".


title: Loaded Weapon 1

text: Clifford Terry had a more mixed review of the film; in the "Chicago Tribune" he remarked that "the salt-and-pepper protagonists are no-nonsense, rapid-firing cops down to their very names: Colt and Luger. Obviously, "National Lampoon's Loaded Weapon I" is designed as a sendup of the "Lethal Weapon" movies, but the benchmarks are really "Police Academy" and "". Once again, criminal activity is the game but sophomoric silliness and tastelessness call the shots."


title: Loaded Weapon 1

text: "Loaded Weapon 1" has an 18% score on the film-critic aggregator Rotten Tomatoes, based on 35 reviews with the consensus: ""Loaded Weapon 1" hits all the routine targets with soft squibs, yielding a tired parody that cycles through its laundry list of references with little comedic verve".


title: Parliament House, New Delhi

text: The Parliament House (IAST: ) in New Delhi is the seat of the Parliament of India. Its houses the Lok Sabha and the Rajya Sabha which represent lower and upper houses respectively in India's bicameral parliament.


title: Parliament House, New Delhi

text: At a distance of 750 meters from the Rashtrapati Bhavan, it is located on Sansad Marg which crosses the Central Vista and is surrounded by the Vijay Chowk, India Gate(All India War Memorial), National War Memorial (India), Vice President's House, Hyderabad House, Secretariat Building, Prime minister's office and residence, ministerial buildings and other administrative units of Indian government.


title: Parliament House, New Delhi

text: The building was designed by the British architects Edwin Lutyens and Herbert Baker and was constructed between 1921 and 1927. It was opened in January 1927 as the seat of the Imperial Legislative Council. Following the end of British rule in India, it was taken over by the Constituent Assembly, and then by the Indian Parliament once India's Constitution came into force in 1950.


title: Parliament House, New Delhi

text: A new building to house Parliament is under construction directly opposite the current building as part of the Indian government's Central Vista Redevelopment Project.


title: Parliament House, New Delhi

text: Originally called the "House of Parliament", it was designed by the British architects Edwin Lutyens and Herbert Baker in 1912-1913 as part of their wider mandate to construct a new administrative capital city for India. Construction of the Parliament House began in 1921 and it was completed in 1927.


title: Parliament House, New Delhi

text: The foundation stone was laid by HRH Prince Arthur, Duke of Connaught and Strathearn, in February 1921. It took five years to complete the building. On 18 January 1927, Sir Bhupendra Nath Mitra, Member of the Governor-General's Executive Council, in charge of the Department of Industries and Labour, invited Lord Irwin Viceroy of India to open the building. The third session of Central Legislative Assembly was held in this house on 19 January 1927.


title: Parliament House, New Delhi

text: The Parliament Museum, opened in 2006, stands next to the Parliament House in the building of the Parliamentary Library.


title: Parliament House, New Delhi

text: The perimeter of the building is circular, with 144 columns on the outside. At the centre of the building is the circular Central Chamber, and surrounding this Chamber are three semicircular halls that were constructed for the sessions of the Chamber of Princes (now used as the Library Hall), the State Council (now used for the Rajya Sabha), and the Central Legislative Assembly (now used for the Lok Sabha). The parliament is surrounded by large gardens and the perimeter is fenced off by sandstone railings ("jali").


title: Parliament House, New Delhi

text: Some sources speculate that the design of the building was inspired by the Chausath Yogini temple in Morena.


title: Parliament House, New Delhi

text: The current building is planned to be converted into a "Museum of Democracy" after the new Parliament House is operational.


title: Parliament House, New Delhi

text: Proposals for a new parliament building to replace Parliament House emerged in the early 2010s as a result of questions being asked about the stability of the original structure. In 2012, a committee was assembled by the then-Speaker, Mira Kumar, to suggest and assess several alternatives to the usage of the building.


title: Parliament House, New Delhi

text: In 2019, the Indian government launched the Central Vista Redevelopment Project, a multi-billion dollar project to redevelop the Central Vista, India's central administrative area near Raisina Hill, New Delhi. The construction of a new parliament building, as well as redeveloping the Rajpath will create a new office and residence for the Indian prime minister, as well as combining all ministerial buildings in a single central secretariat.


title: Parliament House, New Delhi

text: The groundbreaking ceremony for the new building was held in October 2020 and the foundation stone was laid on 10 December 2020.


title: Parliament House, New Delhi

text: The 2001 Indian Parliament attack was a terrorist attack on the Parliament of India in New Delhi, India on 13 December 2001. The perpetrators belonged to Lashkar-e-Taiba (LeT) and Jaish-e-Mohammed (JeM) - two Pakistan-raised terrorist organisations.[1][3] The attack led to the deaths of six Delhi Police personnel, two Parliament Security Service personnel, and a gardener – in total 9 – and led to increased tensions between India and Pakistan, resulting in the 2001–02 India–Pakistan standoff. The 5 terrorists were killed outside the parliament.


title: Horn (anatomy)

text: A horn is a permanent pointed projection on the head of various animals that consists of a covering of keratin and other proteins surrounding a core of live bone. Horns are distinct from antlers, which are not permanent.


title: Horn (anatomy)

text: In mammals, true horns are found mainly among the ruminant artiodactyls, in the families Antilocapridae (pronghorn) and Bovidae (cattle, goats, antelope etc.). Cattle horns arise from subcutaneous connective tissue (under the scalp) and later fuse to the underlying frontal bone.


title: Horn (anatomy)

text: One pair of horns is usual; however, two or more pairs occur in a few wild species and in some domesticated breeds of sheep. Polycerate (multi-horned) sheep breeds include the Hebridean, Icelandic, Jacob, Manx Loaghtan, and the Navajo-Churro.


title: Horn (anatomy)

text: Horns usually have a curved or spiral shape, often with ridges or fluting. In many species, only males have horns. Horns start to grow soon after birth and continue to grow throughout the life of the animal (except in pronghorns, which shed the outer layer annually, but retain the bony core). Partial or deformed horns in livestock are called scurs. Similar growths on other parts of the body are not usually called horns, but spurs, claws, or hooves, depending on the part of the body on which they occur.


title: Horn (anatomy)

text: The term "horn" is also popularly applied to other hard and pointed features attached to the head of animals in various other families:


title: Horn (anatomy)

text: Many mammal species in various families have tusks, which often serve the same functions as horns, but are in fact oversized teeth. These include the Moschidae (Musk deer, which are ruminants), Suidae (Wild Boars), Proboscidea (Elephants), Monodontidae (Narwhals) and Odobenidae (Walruses).


title: Horn (anatomy)

text: Polled animals or "pollards" are those of normally-horned (mainly domesticated) species whose horns have been removed, or which have not grown. In some cases such animals have small horny growths in the skin where their horns would be – these are known as "scurs".


title: Horn (anatomy)

text: Cases of people growing horns have been historically described, sometimes with mythical status. Researchers have not however discovered photographic evidence of the phenomenon. There are human cadaveric specimens that show outgrowings, but these are instead classified as osteomas or other excrescences.


title: Horn (anatomy)

text: The phenomenon of humans with horns has been observed in countries lacking advanced medicine. There are living people, several in China, with cases of cutaneous horns, most common in the elderly.


title: Horn (anatomy)

text: Some people, notably The Enigma, have horn implants; that is, they have implanted silicone beneath the skin as a form of body modification.


title: Horn (anatomy)

text: Animals have a variety of uses for horns and antlers, including defending themselves from predators and fighting members of their own species ("horn fighting") for territory, dominance or mating priority. Horns are usually present only in males but in some species, females too may possess horns. It has been theorized by researchers that taller species living in the open are more visible from longer distances and more likely to benefit from horns to defend themselves against predators. Female bovids that are not hidden from predators due to their large size or open savannahlike habitat are more likely to bear horns than small or camouflaged species.


title: Horn (anatomy)

text: In addition, horns may be used to root in the soil or strip bark from trees. In animal courtship many use horns in displays. For example, the male blue wildebeest reams the bark and branches of trees to impress the female and lure her into his territory. Some animals with true horns use them for cooling. The blood vessels in the bony core allow the horns to function as a radiator.


title: Horn (anatomy)

text: In some instances, wildlife parks may decide to remove the horn of some animals (such as rhinos) as a preventive measure against poaching. Animal horns can be safely sawn off without hurting the animal (it is similar to clipping toe nails). When the animal were to be poached, the animal is generally killed as it is shot first. Park rangers however may decide to tranquilize the animal instead to remove the horn.


title: Committee

text: A committee or commission is a body of one or more persons subordinate to a deliberative assembly. A committee is not itself considered to be a form of assembly. Usually, the assembly sends matters into a committee as a way to explore them more fully than would be possible if the assembly itself were considering them. Committees may have different functions and their types of work differ depending on the type of the organization and its needs.


title: Committee

text: A member of a legislature may be delegated a committee assignment, which gives them the right to serve on a certain committee.


title: Committee

text: A deliberative assembly may form a committee (or "commission") consisting of one or more persons to assist with the work of the assembly. For larger organizations, much work is done in committees. Committees can be a way to formally draw together people of relevant expertise from different parts of an organization who otherwise would not have a good way to share information and coordinate actions. They may have the advantage of widening viewpoints and sharing out responsibilities. They can also be appointed with experts to recommend actions in matters that require specialized knowledge or technical judgment.


title: Committee

text: Generally, committees are required to report to their parent body. Committees do not usually have the power to act independently unless the body that created it gives it such power.


title: Committee

text: When a committee is formed, a chairman (or "chair" or "chairperson") is designated for the committee. Sometimes a vice-chairman (or similar name) is also appointed. It is common for the committee chairman to organize its meetings. Sometimes these meetings are held through videoconferencing or other means if committee members are not able to attend in person, as may be the case if they are in different parts of the country or the world.


title: Committee

text: The chairman is responsible for running meetings. Duties include keeping the discussion on the appropriate subject, recognizing members to speak, and confirming what the committee has decided (through voting or by unanimous consent). Using "Roberts Rules of Order Newly Revised" (RONR), committees may follow informal procedures (such as not requiring motions if it's clear what is being discussed). The level of formality depends on the size and type of committee, in which sometimes larger committees considering crucial issues may require more formal processes.


title: Committee

text: Minutes are a record of the decisions at meetings. They can be taken by a person designated as the secretary. For most organizations, committees are not required to keep formal minutes. However, some bodies require that committees take minutes, especially if the committees are public ones subject to open meeting laws.


title: Committee

text: Committees may meet on a regular basis, such as weekly or more often, or meetings may be called irregularly as the need arises. The frequency of the meetings depends on the work of the committee and the needs of the parent body.


title: Committee

text: When the committee completes its work, it provides the results in a report to its parent body. The report may include the methods used, the facts uncovered, the conclusions reached, and any recommendations. If the committee is not ready to report, it may provide a partial report or the assembly may discharge the committee of the matter so that the assembly can handle it. Also, if members of the committee are not performing their duties, they may be removed or replaced by the appointing power. Whether the committee continues to exist after presenting its report depends on the type of committee. Generally, committees established by the bylaws or the organization's rules continue to exist, while committees formed for a particular purpose go out of existence after the final report.


title: Committee

text: In parliamentary procedure, the motion to commit (or refer) is used to refer another motion—usually a main motion—to a committee.


title: Committee

text: A motion to commit should specify to which committee the matter is to be referred, and if the committee is a special committee appointed specifically for purposes of the referred motion, it should also specify the number of committee members and the method of their selection, unless that is specified in the bylaws.


title: Committee

text: Any proposed amendments to the main motion that are pending at the time the motion is referred to a committee go to the committee as well.


title: Committee

text: Once referred, but before the committee reports its recommendations back to the assembly, the referred motion may be removed from the committee's consideration by the motion to discharge a committee.


title: Committee

text: In the United States House of Representatives, a motion to recommit can be made with or without instructions. If the motion is made without instructions, the bill or resolution is simply sent back to the committee. If the motion is made with instructions and the motion is agreed to, the chairman of the committee in question will immediately report the bill or resolution back to the whole House with the new language. In this sense, a motion to recommit with instructions is effectively an amendment.


title: Committee

text: In "Robert's Rules of Order Newly Revised" ("RONR"), the motion to commit has three variations which do not turn a question over to a smaller group, but simply permit the assembly's full meeting body to consider it with the greater freedom of debate that is allowed to committees. These forms are to go into a committee of the whole, to go into a quasi-committee of the whole, and to consider informally. Passing any of these motions removes the limitations on the number of times a member can speak. "The Standard Code of Parliamentary Procedure" has informal consideration, but does not have "committee of the whole" and "quasi committee of the whole".


title: Committee

text: In "Robert's Rules of Order Newly Revised", the motion to discharge a committee is used to take a matter out of a committee's hands before the committee has made a final report on it. A committee can use this motion to discharge a subcommittee.


title: Committee

text: The vote required is a majority vote if the committee has failed to report at the prescribed time or if the assembly is considering a partial report of the committee. Otherwise, it requires a majority vote with previous notice; or a two-thirds vote; or a majority of the entire membership.


title: Committee

text: Under "The Standard Code of Parliamentary Procedure", the assembly that has referred a motion or a matter to a committee may, by a majority vote, withdraw it at any time from the committee, refer it to another committee, or decide the question itself.


title: Committee

text: Organizations with a large board of directors (such as international labor unions, large corporations with thousands of stock holders or national and international organizations) may have a smaller body of the board, called an "executive committee", handle its business. The executive committee may function more like a board than an actual committee. In any case, an executive committee can only be established through a specific provision in the charter or bylaws of the entity (i.e. a board cannot appoint an executive committee without authorization to do so). Members of the executive committee may be elected by the overall franchised membership or by the board, depending on the rules of the organization, and usually consist of the CEO and the Vice Presidents in charge of respective directorates within the organization. However formed, an executive committee only has such powers and authority that the governing documents of the organization give it. In some cases, it may be empowered to act on behalf of the board or organization, while in others, it may only be able to make recommendations.


title: Committee

text: Governments at the national level may have a "conference committee". A conference committee in a bicameral legislature is responsible for creating a compromise version of a particular bill when each house has passed a different version.


title: Committee

text: A conference committee in the United States Congress is a temporary panel of negotiators from the House of Representatives and the Senate. Unless one chamber decides to accept the other's original bill, the compromise version must pass both chambers after leaving the conference committee. The committee is usually composed of the senior members of the standing committees that originally considered the legislation in each chamber.


title: Committee

text: Other countries that use conference committees include France, Germany, Japan, and Switzerland. In Canada, conference committees have been unused since 1947. In the European Union (EU) legislative process, a similar committee is called a 'Conciliation Committee', which carries out the Trilogue negotiations in case the Council does not agree with a text amended and adopted by the European Parliament at a second reading. Although the practice has fallen out of favour in other Australian Parliaments, the Parliament of South Australia still regularly appoints a "Conference of Managers" from each House to negotiate compromises on disputed bills in private.


title: Committee

text: In organizations, the term "conference committee" may have a different meaning. This meaning may be associated with the conferences, or conventions, that the organization puts together. The committees that are responsible for organizing such events may be called "conference committees".


title: Committee

text: A standing committee is a subunit of a political or deliberative body established in a permanent fashion to aid the parent assembly in accomplishing its duties, for example by meeting on a specific, permanent policy domain (e.g. defence, health, or trade and industry). A standing committee is granted its scope and powers over a particular area of business by the governing documents. Standing committees meet on a regular or irregular basis depending on their function, and retain any power or oversight originally given them until subsequent official actions of the governing body (through changes to law or by-laws) disbands the committee.


title: Committee

text: Most governmental legislative committees are standing committees. The phrase is used in the legislatures of the following countries:


title: Committee

text: Under the laws of the United States of America, a standing committee is a Congressional committee permanently authorized by United States House of Representatives and United States Senate rules. The Legislative Reorganization Act of 1946 greatly reduced the number of committees, and set up the legislative committee structure still in use today, as modified by authorized changes via the orderly mechanism of rules changes.


title: Committee

text: Examples of standing committees in organizations are an audit committee, an elections committee, a finance committee, a fundraising committee, a governance committee, and a program committee. Typically, the standing committees perform their work throughout the year and present their reports at an annual meeting of the organization. These committees continue to exist after presenting their reports, although the membership in the committees may change.


title: Committee

text: A nominating committee (or nominations committee) is a group formed for the purpose of nominating candidates for office or the board in an organization. It may consist of members from inside the organization. Sometimes a governance committee takes the role of a nominating committee. Depending on the organization, this committee may be empowered to actively seek out candidates or may only have the power to receive nominations from members and verify that the candidates are eligible.


title: Committee

text: A nominating committee works similarly to an electoral college, the main difference being that the available candidates, either nominated or "written in" outside of the committee's choices, are then voted into office by the membership. It is a part of governance methods often employed by corporate bodies, business entities, and social and sporting groups, especially clubs. The intention is that they be made up of qualified and knowledgeable people representing the best interests of the membership. In the case of business entities, their directors will often be brought in from outside, and receive a benefit for their expertise.


title: Committee

text: In the context of nominations for awards, a nominating committee can also be formed for the purpose of nominating persons or things held up for judgment by others as to their comparative quality or value, especially for the purpose of bestowing awards in the arts, or in application to industry's products and services. The objective being to update, set, and maintain high and possibly new standards.


title: Committee

text: A steering committee is a committee that provides guidance, direction and control to a project within an organization. The term is derived from the steering mechanism that changes the steering angle of a vehicle's wheels.


title: Committee

text: Project steering committees are frequently used for guiding and monitoring IT projects in large organizations, as part of project governance. The functions of the committee might include building a business case for the project, planning, providing assistance and guidance, monitoring the progress, controlling the project scope and resolving conflicts.


title: Committee

text: As with other committees, the specific duties and role of the steering committee vary among organizations.


title: Committee

text: A special committee (also working, select, or ad hoc committee) is established to accomplish a particular task or to oversee a specific area in need of control or oversight. Many are research or coordination committees in type or purpose, and are temporary. Some are a sub-group of a larger society with a particular area of interest which are organized to meet and discuss matters pertaining to their interests. For example, a group of astronomers might be organized to discuss how to get the larger society to address near Earth objects. A subgroup of engineers and scientists of a large project's development team could be organized to solve some particular issue with offsetting considerations and trade-offs. Once the committee makes its final report to its parent body, the special committee ceases to exist.


title: Committee

text: A committee that is a subset of a larger committee is called a "subcommittee". Committees that have a large workload may form subcommittees to further divide the work. Subcommittees report to the parent committee and not to the general assembly.


title: Committee

text: When the entire assembly meets as a committee to discuss or debate, this is called a "committee of the whole". This is not an actual committee but a procedural device that is more commonly used in legislative bodies.


title: Committee

text: "Central Committee" was the common designation of a standing administrative body of communist parties, analogous to a board of directors, whether ruling or non-ruling in the 20th century and of surviving communist states in the 21st century. In such party organizations the committee would typically be made up of delegates elected at a party congress. In those states where it constituted the state power, the Central Committee made decisions for the party between congresses, and usually was (at least nominally) responsible for electing the Politburo. In non-ruling Communist parties, the Central Committee is usually understood by the party membership to be the ultimate decision-making authority between Congresses once the process of democratic centralism has led to an agreed-upon position.


title: Chimpanzee–human last common ancestor

text: The chimpanzee–human last common ancestor (CHLCA) is the last common ancestor shared by the extant "Homo" (human) and "Pan" (chimpanzee and bonobo) genera of Hominini. Due to complex hybrid speciation, it is not currently possible to give a precise estimate on the age of this ancestral population. While "original divergence" between populations may have occurred as early as 13 million years ago (Miocene), hybridization may have been ongoing until as recently as 4 million years ago (Pliocene).


title: Chimpanzee–human last common ancestor

text: In human genetic studies, the CHLCA is useful as an anchor point for calculating single-nucleotide polymorphism (SNP) rates in human populations where chimpanzees are used as an outgroup, that is, as the extant species most genetically similar to "Homo sapiens".


title: Chimpanzee–human last common ancestor

text: The taxon tribe "Hominini" was proposed to separate humans (genus "Homo") from chimpanzees ("Pan") and gorillas (genus "Gorilla") on the notion that the least similar species should be separated from the other two. However, later evidence revealed that "Pan" and "Homo" are closer genetically than are "Pan" and "Gorilla"; thus, "Pan" was referred to the tribe "Hominini" with "Homo". "Gorilla" now became the separated genus and was referred to the new taxon 'tribe Gorillini'.


title: Chimpanzee–human last common ancestor

text: Mann and Weiss (1996), proposed that the tribe "Hominini" should encompass "Pan" and "Homo", grouped in separate subtribes. They classified "Homo" and all bipedal apes in the subtribe Hominina and "Pan" in the subtribe Panina. (Wood (2010) discussed the different views of this taxonomy.) A "chimpanzee clade" was posited by Wood and Richmond, who referred it to a tribe "Panini", which was envisioned from the family "Hominidae" being composed of a trifurcation of subfamilies.


title: Chimpanzee–human last common ancestor

text: Richard Wrangham (2001) argued that the CHLCA species was very similar to the common chimpanzee ("Pan troglodytes") – so much so that it should be classified as a member of the genus "Pan" and be given the taxonomic name "Pan prior".


title: Chimpanzee–human last common ancestor

text: All the human-related genera of tribe Hominini that arose "after" divergence from "Pan" are members of the subtribe "Hominina", including the genera "Homo" and "Australopithecus". This group represents "the human clade" and its members are called "hominins".


title: Chimpanzee–human last common ancestor

text: No fossil has yet conclusively been identified as the CHLCA. A possible candidate is "Graecopithecus". This would put the CHLCA split in Southeast Europe instead of Africa.


title: Chimpanzee–human last common ancestor

text: "Sahelanthropus tchadensis" is an extinct hominine with some morphology proposed (and disputed) to be as expected of the CHLCA, and it lived some 7 million years ago – close to the time of the chimpanzee–human divergence. But it is unclear whether it should be classified as a member of the tribe Hominini, that is, a hominin, as an ancestor of "Homo" and "Pan" and a potential candidate for the CHLCA species itself, or simply a Miocene ape with some convergent anatomical similarity to many later hominins.


title: Chimpanzee–human last common ancestor

text: "Ardipithecus" most likely appeared after the human-chimpanzee split, some 5.5 million years ago, at a time when hybridization may still have been ongoing. It has several shared characteristics with chimpanzees, but due to its fossil incompleteness and the proximity to the human-chimpanzee split, the exact position of "Ardipithecus" in the fossil record is unclear. It is most likely derived from the chimpanzee lineage and thus not ancestral to humans. However, Sarmiento (2010), noting that "Ardipithecus" does not share any characteristics exclusive to humans and some of its characteristics (those in the wrist and basicranium), suggested that it may have diverged from the common human/African ape stock prior to the human, chimpanzee and gorilla divergence.


title: Chimpanzee–human last common ancestor

text: The earliest fossils clearly in the human but not the chimpanzee lineage appear between about 4.5 to 4 million years ago, with "Australopithecus anamensis".


title: Chimpanzee–human last common ancestor

text: Few fossil specimens on the "chimpanzee-side" of the split have been found; the first fossil chimpanzee, dating between 545 and 284 kyr (thousand years, radiometric), was discovered in Kenya's East African Rift Valley (McBrearty, 2005). All extinct genera listed in the taxobox are ancestral to "Homo", or are offshoots of such. However, both "Orrorin" and "Sahelanthropus" existed around the time of the divergence, and so either one or both may be ancestral to both genera "Homo" and "Pan".


title: Chimpanzee–human last common ancestor

text: Due to the scarcity of fossil evidence for CHLCA candidates, Mounier (2016) presented a project to create a "virtual fossil" by applying digital "morphometrics" and statistical algorithms to fossils from across the evolutionary history of both "Homo" and "Pan", having previously used this technique to visualize a skull of the last common ancestor of "Neanderthal" and "Homo sapiens".


title: Chimpanzee–human last common ancestor

text: An estimate of T of 10 to 13 million years was proposed in 1998, and a range of 7 to 10 million years ago is assumed by White et al. (2009):


title: Chimpanzee–human last common ancestor

text: Some researchers tried to estimate the age of the CHLCA (T) using biopolymer structures that differ slightly between closely related animals. Among these researchers, Allan C. Wilson and Vincent Sarich were pioneers in the development of the molecular clock for humans. Working on protein sequences, they eventually (1971) determined that apes were closer to humans than some paleontologists perceived based on the fossil record. Later, Vincent Sarich concluded that the T was no older than 8 million years in age, with a favored range between 4 and 6 million years before present.


title: Chimpanzee–human last common ancestor

text: This paradigmatic age has stuck with molecular anthropology until the late 1990s. Since the 1990s, the estimate has again been pushed towards more-remote times, because studies have found evidence for a slowing of the molecular clock as apes evolved from a common monkey-like ancestor with monkeys, and humans evolved from a common ape-like ancestor with non-human apes.


title: Chimpanzee–human last common ancestor

text: A 2016 study analyzed transitions at CpG sites in genome sequences, which exhibit a more clocklike behavior than other substitutions, arriving at an estimate for human and chimpanzee divergence time of 12.1 million years.


title: Chimpanzee–human last common ancestor

text: A source of confusion in determining the exact age of the "Pan"–"Homo" split is evidence of a more complex speciation process than a clean split between the two lineages. Different chromosomes appear to have split at different times, possibly over as much as a 4-million-year period, indicating a long and drawn out speciation process with large-scale hybridization events between the two emerging lineages as recently as 6.3 to 5.4 million years ago, according to Patterson et al. (2006).


title: Chimpanzee–human last common ancestor

text: Speciation between "Pan" and "Homo" occurred over the last 9 million years. "Ardipithecus" probably branched off of the "Pan" lineage in the middle Miocene Messinian. After the original divergences, there were, according to Patterson (2006), periods of hybridization between population groups and a process of alternating divergence and hybridization that lasted several million years. Some time during the late Miocene or early Pliocene, the earliest members of the human clade completed a final separation from the lineage of "Pan" – with date estimates ranging from 13 million to as recent as 4 million years ago. The latter date and the argument for hybridization events are rejected by Wakeley.


title: Chimpanzee–human last common ancestor

text: The assumption of late hybridization was in particular based on the similarity of the X chromosome in humans and chimpanzees, suggesting a divergence as late as some 4  million years ago. This conclusion was rejected as unwarranted by Wakeley (2008), who suggested alternative explanations, including selection pressure on the X chromosome in the populations ancestral to the CHLCA.


title: Chimpanzee–human last common ancestor

text: Complex speciation and incomplete lineage sorting of genetic sequences seem to also have happened in the split between the human lineage and that of the gorilla, indicating "messy" speciation is the rule rather than the exception in large primates. Such a scenario would explain why the divergence age between the "Homo" and "Pan" has varied with the chosen method and why a single point has so far been hard to track down.


title: Sassafras albidum

text: Sassafras albidum (sassafras, white sassafras, red sassafras, or silky sassafras) is a species of "Sassafras" native to eastern North America, from southern Maine and southern Ontario west to Iowa, and south to central Florida and eastern Texas. It occurs throughout the eastern deciduous forest habitat type, at altitudes of up to above sea level. It formerly also occurred in southern Wisconsin, but is extirpated there as a native tree.


title: Sassafras albidum

text: "Sassafras albidum" is a medium-sized deciduous tree growing to tall, with a canopy up to wide, with a trunk up to in diameter, and a crown with many slender sympodial branches. The bark on trunk of mature trees is thick, dark red-brown, and deeply furrowed. The shoots are bright yellow green at first with mucilaginous bark, turning reddish brown, and in two or three years begin to show shallow fissures. The leaves are alternate, green to yellow-green, ovate or obovate, long and broad with a short, slender, slightly grooved petiole. They come in three different shapes, all of which can be on the same branch; three-lobed leaves, unlobed elliptical leaves, and two-lobed leaves; rarely, there can be more than three lobes. In fall, they turn to shades of yellow, tinged with red. The flowers are produced in loose, drooping, few-flowered racemes up to long in early spring shortly before the leaves appear; they are yellow to greenish-yellow, with five or six tepals. It is usually dioecious, with male and female flowers on separate trees; male flowers have nine stamens, female flowers with six staminodes (aborted stamens) and a 2–3 mm style on a superior ovary. Pollination is by insects. The fruit is a dark blue-black drupe long containing a single seed, borne on a red fleshy club-shaped pedicel long; it is ripe in late summer, with the seeds dispersed by birds. The cotyledons are thick and fleshy. All parts of the plant are aromatic and spicy. The roots are thick and fleshy, and frequently produce root sprouts which can develop into new trees.


title: Sassafras albidum

text: It prefers rich, well-drained sandy loam with a pH of 6–7, but will grow in any loose, moist soil. Seedlings will tolerate shade, but saplings and older trees demand full sunlight for good growth; in forests it typically regenerates in gaps created by windblow. Growth is rapid, particularly with root sprouts, which can reach in the first year and in 4 years. Root sprouts often result in dense thickets, and a single tree, if allowed to spread unrestrained, will soon be surrounded by a sizable clonal colony, as its roots extend in every direction and send up multitudes of shoots.


title: Sassafras albidum

text: Laurel wilt is a highly destructive disease initiated when the invasive flying redbay ambrosia beetle ("Xyleborus glabratus") introduces its highly virulent fungal symbiont ("Raffaelea lauricola") into the sapwood of Lauraceae host shrubs or trees. Sassafras's volatile terpenoids may attract "X. glabratus". Sassafras is susceptible to laurel wilt and capable of supporting broods of "X. glabratus". Underground transmission of the pathogen through roots and stolons of Sassafras without evidence of "X. glabratus" attack is suggested. Studies examining the insect's cold tolerance showed that "X. glabratus" may be able to move to colder northern areas where sassafras would be the main host. The exotic Asian insect is spreading the epidemic from the Everglades through the Carolinas in perhaps less than 15 years by the end of 2014.


title: Sassafras albidum

text: All parts of the "Sassafras albidum" plant have been used for human purposes, including stems, leaves, bark, wood, roots, fruit, and flowers. "Sassafras albidum", while native to North America, is significant to the economic, medical, and cultural history of both Europe and North America. In North America, it has particular culinary significance, being featured in distinct national foods such as traditional root beer, filé powder, and Louisiana Creole cuisine. "Sassafras albidum" was an important plant to many Native Americans of the southeastern United States and was used for many purposes, including culinary and medicinal purposes, before the European colonization of North America. Its significance for Native Americans is also magnified, as the European quest for sassafras as a commodity for export brought Europeans into closer contact with Native Americans during the early years of European settlement in the 16th and 17th centuries, in Florida, Virginia, and parts of the Northeast.


title: Sassafras albidum

text: "Sassafras albidum" was a well-used plant by Native Americans in what is now the Southeastern United States prior to the European colonization. The Choctaw word for sassafras is "Kvfi," and it was by them principally as a soup thickener. It was known as "Winauk" in Delaware and Virginia and is called "Pauame" by the Timuca.


title: Sassafras albidum

text: Some Native American tribes used the leaves of sassafras to treat wounds by rubbing the leaves directly into a wound, and used different parts of the plant for many medicinal purposes such as treating acne, urinary disorders, and sicknesses that increased body temperature, such as high fevers. They also used the bark as a dye, and as a flavoring.


title: Sassafras albidum

text: Sassafras wood was also used by Native Americans in the Southeastern United States as a fire-starter because of the flammability of its natural oils.


title: Sassafras albidum

text: In cooking, sassafras was used by some Native Americans to flavor bear fat, and to cure meats. Sassafras is still used today to cure meats. Use of filé powder by the Choctaw in the Southern United States in cooking is linked to the development of gumbo, a signature dish of Louisiana Creole cuisine.


title: Sassafras albidum

text: "Sassafras albidum" is used primarily in the United States as the key ingredient in home brewed root beer and as a thickener and flavouring in traditional Louisiana Creole gumbo.


title: Sassafras albidum

text: Filé powder, also called gumbo filé, for its use in making gumbo, is a spicy herb made from the dried and ground leaves of the sassafras tree. It was traditionally used by Native Americans in the Southern United States, and was adopted into Louisiana Creole cuisine. Use of filé powder by the Choctaw in the Southern United States in cooking is linked to the development of gumbo, the signature dish of Louisiana Creole cuisine that features ground sassafras leaves. The leaves and root bark can be pulverized to flavor soup and gravy, and meat, respectively.


title: Sassafras albidum

text: Sassafras roots are used to make traditional root beer, although they were banned for commercially mass-produced foods and drugs by the U.S. Food and Drug Administration in 1960. Laboratory animals that were given oral doses of sassafras tea or sassafras oil that contained large doses of safrole developed permanent liver damage or various types of cancer. In humans, liver damage can take years to develop and it may not have obvious signs. Along with commercially available sarsaparilla, sassafras remains an ingredient in use among hobby or microbrew enthusiasts. While sassafras is no longer used in commercially produced root beer and is sometimes substituted with artificial flavors, natural extracts with the safrole distilled and removed are available. Most commercial root beers have replaced the sassafras extract with methyl salicylate, the ester found in wintergreen and black birch ("Betula lenta") bark.


title: Sassafras albidum

text: Sassafras tea was also banned in the U.S. in 1977, but the ban was lifted with the passage of the Dietary Supplement Health and Education Act in 1994.


title: Sassafras albidum

text: Safrole can be obtained fairly easily from the root bark of "Sassafras albidum" via steam distillation. It has been used as a natural insect or pest deterrent. Godfrey's Cordial, as well as other tonics given to children that consisted of opiates, used sassafras to disguise other strong smells and odours associated with the tonics. It was also used as an additional flavouring to mask the strong odours of homemade liquor in the United States.


title: Sassafras albidum

text: Commercial "sassafras oil," which contains safrole, is generally a byproduct of camphor production in Asia or comes from related trees in Brazil. Safrole is a precursor for the manufacture of the drug MDMA, as well as the drug MDA (3-4 methylenedioxyamphetamine) and as such, its transport is monitored internationally. Safrole is a List I precursor chemical according to the U.S. Drug Enforcement Administration.


title: Sassafras albidum

text: The wood is dull orange brown, hard, and durable in contact with the soil; it was used in the past for posts and rails, small boats and ox-yokes, though scarcity and small size limits current use. Some is still used for making furniture.


title: Sassafras albidum

text: Europeans were first introduced to sassafras, along with other plants such as cranberries, tobacco, and North American ginseng, when they arrived in North America.


title: Sassafras albidum

text: The aromatic smell of sassafras was described by early European settlers arriving in North America. According to one legend, Christopher Columbus found North America because he could smell the scent of sassafras. As early as the 1560s, French visitors to North America discovered the medicinal qualities of sassafras, which was also exploited by the Spanish who arrived in Florida. English settlers at Roanoke reported surviving on boiled sassafras leaves and dog meat during times of starvation.


title: Sassafras albidum

text: Upon the arrival of the English on the Eastern coast of North America, sassafras trees were reported as plentiful. Sassafras was sold in England and in continental Europe, where it was sold as a dark beverage called "saloop" that had medicinal qualities and used as a medicinal cure for a variety of ailments. The discovery of sassafras occurred at the same time as a severe syphilis outbreak in Europe, when little about this terrible disease was understood, and sassafras was touted as a cure. Sir Francis Drake was one of the earliest to bring sassafras to England in 1586, and Sir Walter Raleigh was the first to export sassafras as a commodity in 1602. Sassafras became a major export commodity to England and other areas of Europe, as a medicinal root used to treat ague (fevers) and sexually transmitted diseases such as syphilis and gonorrhea, and as wood prized for its beauty and durability. Exploration for sassafras was the catalyst for the 1603 commercial expedition from Bristol of Captain Martin Pring to the coasts of present-day Maine, New Hampshire, and Massachusetts. During a brief period in the early 17th century, sassafras was the second-largest export from the British colonies in North America behind tobacco.


title: Sassafras albidum

text: Since the bark was the most commercially valued part of the sassafras plant due to large concentrations of the aromatic safrole oil, commercially valuable sassafras could only be gathered from each tree once. This meant that as significant amounts of sassafras bark were gathered, supplies quickly diminished and sassafras become more difficult to find. For example, while one of the earliest shipments of sassafras in 1602 weighed as much as a ton, by 1626, English colonists failed to meet their 30-pound quota. The gathering of sassafras bark brought European settlers and Native Americans into contact sometimes dangerous to both groups. Sassafras was such a desired commodity in England, that its importation was included in the Charter of the Colony of Virginia in 1610.


title: Sassafras albidum

text: Through modern times the sassafras plant, both wild and cultivated, has been harvested for the extraction of safrole, which is used in a variety of commercial products as well as in the manufacture of illegal drugs like MDMA; yet, sassafras plants in China and Brazil are more commonly used for these purposes than North American "Sassafras albidum".


title: Jasmine Tookes

text: Tookes was born and raised in Huntington Beach, California. She has a younger sister, who is 19 years her junior. She did gymnastics for ten years and was also active in volleyball and softball before she became a model at about the age of 15. Her mother is a celebrity fashion stylist. Tookes was discovered at one of her mother's showroom appointments.


title: Jasmine Tookes

text: Tookes' first commercial ad campaigns were in 2010 for UGG Australia and Gap. Before breaking out on the international scene, she booked a Spring 2011 DKNY campaign and a layout in "Vogue Italia". Models.com named Tookes as one of the top 10 new models in a September 27, 2011, fashion week post. Tookes was selected by "Style" as its top new model in November 2011 based on her work for the Spring Fashion Shows. She was one of eleven new models for the annual Victoria's Secret Fashion Show in 2012. The 2012 show was taped in November and broadcast on the CBS network on December 4. The night before the airing of the fashion show, Tookes and fellow Victoria's Secret models Behati Prinsloo and Jacquelyn Jablonski guest starred on the December 3 "Ha'awe Make Loa" episode of CBS' "Hawaii Five-0". French "Vogue" named her as one of its 10 New faces from fall/winter 2012–2013 Fashion Week.


title: Jasmine Tookes

text: Tookes has appeared in editorials for Italian, American, French, German, and Spanish "Vogue", "Harper's Bazaar", "Numéro", "W", and "V". her cover include Elle France February 2013, Vogue Espana March 2016 alongside her fellow Victoria's Secret Angels, Harper's Bazaar Vietnam July 2016 along with Elsa Hosk and Martha Hunt, Maxim Magazine February 2017, and also Elle USA May 2017.


title: Jasmine Tookes

text: She has walked the runways for Burberry, Salvatore Ferragamo, Carolina Herrera, Moschino, Ralph Lauren, DKNY, Shiatzy Chen, Herve Leger, Ermanno Scervino, Giorgio Armani, Philipp Plein, Missoni, Jason Wu, Alberta Ferretti, Emilio Pucci, Balmain, Marc Jacobs, Oscar de la Renta, Giambattista Valli, Vera Wang, Calvin Klein, Tom Ford, Yves Saint Laurent, Trussardi, Marchesa, Tory Burch, Dolce & Gabbana, Stella McCartney, Paco Rabanne, Helmut Lang, Louis Vuitton, DSquared2, Tommy Hilfiger, Calvin Klein, Tom Ford, Prada, Jill Stuart, rag+bone, Miu Miu and Versace.


title: Jasmine Tookes

text: She has appeared in advertising campaigns for Bobbi Brown Cosmetics, Jimmy Choo, Calvin Klein, Lancôme, DKNY, Ralph Lauren, Kate Spade, Gap, Ugg, and Victoria's Secret. In 2015, she became a Victoria's Secret Angel. Tookes was selected to wear the Victoria's Secret Fashion Show Fantasy Bra (worth $3 million in 2016) at the 2016 show, which was held in Paris, France, which made her the 3rd black model to wear the bra. Tookes made her debut at No. 17 on "Forbes" "The World's Highest Paid Models" list in 2016, with estimated earnings of $4 million.


title: Jasmine Tookes

text: In September 2020, Tookes announced her engagement to her boyfriend of four years, Juan David Borrero. He is the director of international markets of Snap Inc. and the son of doctor Alfredo Borrero Vega, the Vice President of Ecuador. They married on September 4, 2021, at the Iglesia y Convento de San Francisco in Quito, Ecuador. On November 21, 2022, she announced on her Instagram account that they are expecting their first child.


title: John Callahan (cartoonist)

text: John Michael Callahan (February 5, 1951 – July 24, 2010) was an American cartoonist, artist, and musician in Portland, Oregon.


title: John Callahan (cartoonist)

text: Following his accident, he became a cartoonist, drawing by clutching a pen between both hands, having regained partial use of his upper body. His visual artistic style was simple and often rough, although still legible.


title: John Callahan (cartoonist)

text: Callahan's cartoons dealt with subjects often considered taboo, including disabilities and disease. His black humor may be exemplified by the title of his "quasi-memoir," "Will the Real John Callahan Please Stand Up?" The subject matter and treatment of his cartoons share something with the work of Charles Addams, Gahan Wilson, and especially Charles Rodrigues, although it is much more aggressive than even the "Playboy" cartoons by these cartoonists.


title: John Callahan (cartoonist)

text: From 1983 until his death 27 years later, Callahan's work appeared in the Portland newspaper "Willamette Week." The controversial nature of his cartoons occasionally led to boycotts and protests against the paper.


title: John Callahan (cartoonist)

text: Callahan scoffed at the reactions of critics who labeled his work politically incorrect, while delighting in the positive reactions he received from fans with disabilities. "My only compass for whether I've gone too far is the reaction I get from people in wheelchairs, or with hooks for hands." Callahan said. "Like me, they are fed up with people who presume to speak for the disabled. All the pity and the patronizing. That's what is truly detestable."


title: John Callahan (cartoonist)

text: Two animated cartoon series have been based on Callahan's cartoons, both produced by the Canada-based Nelvana: "Pelswick" (on CBC Television) and "Quads!" (on Teletoon).


title: John Callahan (cartoonist)

text: Friends said Callahan realized that his cartooning was a form of emotional venting, which led him to pursue a master's degree in counseling at Portland State University. However, his deteriorating health prevented him from finishing his first term.


title: John Callahan (cartoonist)

text: In 2005, Dutch filmmaker Simone de Vries directed a documentary about Callahan titled "Raak me waar ik voelen kan" (English: "Touch Me Where I Can Feel").


title: John Callahan (cartoonist)

text: Callahan died on July 24, 2010, following surgery for chronic bed sores. His brother stated the causes of his death were complications of quadriplegia and respiratory problems. He was 59 years old.


title: John Callahan (cartoonist)

text: A biographical film, "Don't Worry, He Won't Get Far on Foot" based on Callahan's memoir of the same name, was posthumously released in 2018.


title: John Callahan (cartoonist)

text: Callahan worked on nudes and a portrait project, which was shown in several galleries throughout its progression.


title: John Callahan (cartoonist)

text: Callahan was also a songwriter. He released a CD, "Purple Winos in the Rain", in 2006. He wrote and composed his own lyrics, and sang and played the harmonica and ukulele. The record was released on BoneClone Records and produced by blues musician Terry Robb, who also plays guitar accompaniment on several tracks, with a special cameo appearance by Tom Waits. Callahan personally illustrated the album cover. Posthumously, in 2018, track 14, "Texas When You Go," a duet recording of Callahan and Robb, was included in the film score for "Don't Worry, He Won't Get Far on Foot".


title: John Callahan (cartoonist)

text: "The Independent" called his songs "beautiful, but dark." He wrote all the music and lyrics himself and was backed up by many notable musicians. A Dutch film crew recorded the studio sessions in which Callahan played a simplified piano version of "Roll Away the Day."


title: John Callahan (cartoonist)

text: John Callahan was adopted as an infant and grew up in The Dalles. His adoptive parents later had five biological children. He attended a Roman Catholic elementary school, St Mary's Academy, and graduated from a public high school. He began drinking at the age of 12. "I used the alcohol to hide the pain of the abuse," Callahan said. After the car accident that caused his spinal cord injury, he went through extensive rehabilitation. At the age of 27, he gave up drinking alcohol. He made his home in Portland, Oregon.


title: Volkswagen Beetle (A5)

text: The Volkswagen Beetle (also sold as the Volkswagen Käfer, Volkswagen Coccinelle, Volkswagen Maggiolino, Volkswagen Fusca in some countries) is a small family car manufactured and marketed by Volkswagen introduced in 2011 for the 2012 model year, as the successor to the New Beetle launched in 1997. It features a lower profile while retaining an overall shape recalling the original Volkswagen Type 1 Beetle.


title: Volkswagen Beetle (A5)

text: One of Volkswagen's goals with the model was to give it a more aggressive appearance while giving it some stylistic aspects reminiscent of the Type 1. This was an attempt to distance the new model from the New Beetle, produced from 1997 to 2011, which never approached the success of the first Beetle.


title: Volkswagen Beetle (A5)

text: The second generation "new" Beetle shares the "A5" (PQ35) platform with the current generation Volkswagen Jetta and is built alongside the Jetta, Golf Variant and the old Jetta ("Clásico") at Volkswagen's plant in Puebla, Mexico. It is longer than the previous New Beetle at and also has a lower profile, lower than its predecessor, and wider. The trunk is now , up from .


title: Volkswagen Beetle (A5)

text: A convertible version followed the coupé for the 2013 model year, first shown at the Los Angeles Auto Show in November 2012 when it also went on sale.


title: Volkswagen Beetle (A5)

text: Head of Technical Development for VW, Frank Welsch, indicated at the 2018 Geneva Motor Show that this would be the Beetle's final generation.


title: Volkswagen Beetle (A5)

text: On 13 September 2018, Volkswagen announced that the Beetle production would end in July 2019. The final third generation Beetle (a denim blue coupe) finished production on 9 July 2019 and was presented on the assembly line the next day. The model was officially retired at a ceremony in Puebla City later that day.


title: Volkswagen Beetle (A5)

text: On 22 November 2010, on the final episode of the "Oprah's Favorite Things" special, Oprah Winfrey and Volkswagen announced every audience member that day would receive one of the Beetles upon its release in 2011. VW staff gave the audience their special keys to the car. This was followed by a teaser commercial during Super Bowl XLV in February 2011.


title: Volkswagen Beetle (A5)

text: To celebrate the global reveal, VW partnered with MTV, to make a debut on three continents on 18 April. The reveal began in Shanghai, China with a MTV Sound System celebration hosted by MTV VJs, followed by MTV World Stage events in Berlin and New York City.


title: Volkswagen Beetle (A5)

text: On 18 April 2011, the 2012 model was unveiled as the Volkswagen Beetle, dropping the word "New" from its name. It debuted at the 14th Auto Shanghai and the New York International Auto Show.


title: Volkswagen Beetle (A5)

text: During the marketing campaign at Mexico, it was advertised as "The new Vocho" (oddly in English) in the "Das Auto" marketing campaign.


title: Volkswagen Beetle (A5)

text: The new model retains the front-engine, front-wheel-drive layout of the New Beetle, while improving interior packaging with more room in the rear. Four-cylinder engine options for the European market are expected to include 1.2-litre (), 1.4-litre () and 2.0-litre () TSI petrol engines, and 1.6-litre () and 2.0-litre () TDI diesel engines. In addition to the 2.0-litre TSI and TDI engines, base North American Beetles were originally fitted with a () straight-five engine (engine code CBTA/CBUA) earlier used on the Golf and Jetta. From 2015 onward, the 2.5L straight-five was phased out in favor of a 1.8L four-cylinder TSI of comparable horsepower ratings but improved torque ratings over the straight-five.


title: Volkswagen Beetle (A5)

text: All engines for this model are offered with an option of a six-speed manual transmission or the option of a dual-clutch DSG automatic. In the United States, transmissions on petrol models come with either a five-speed manual or optional six-speed automatic on 2.5/1.8T models, while on the diesel models there is the option of a DSG six-speed dual-clutch transmission.


title: Volkswagen Beetle (A5)

text: The first special edition of the 2012 Beetle is the Black Turbo launch edition. It was limited to 600 cars on the U.S. market and will be the first car available through Volkswagen’s new Vehicle Pre-Order program.


title: Volkswagen Beetle (A5)

text: A Beetle Turbo Black made an appearance at the 30th annual Wörthersee Treffen in June 2011 in Reifnitz, Austria. It was located on the floating barge showcase at the entrance to the show. Other cars on the barge included a Reifnitz Edition GTI and the Touareg Racer.


title: Volkswagen Beetle (A5)

text: The e-Bugster was a concept vehicle shown at the North American International Auto Show in January 2012; it is a battery-electric vehicle using a motor drawing from a 28.3 kW-hr lithium ion traction battery, for a range of . It previewed the styling for an anticipated convertible edition of the A5; compared to the conventional Beetle, the e-Bugster was wider and the roof was shorter. Unlike other new Beetles, the E-Bugster is a two-seater, true to its Speedster styling, instead of 2+2. Volkswagen allowed journalist Damon Lavrinc to drive the prototype and explained the powertrain components were taken from the contemporary e-Golf that shared the VW PQ35 platform, produced for the California market. Top speed was limited to for the test drive.


title: Volkswagen Beetle (A5)

text: In 2012, Volkswagen partnered with Fender Musical Instruments Corporation to release a limited edition Beetle for the 2013 model year. The Beetle Fender Edition uses the Beetle Turbo's front fascia and the 2.5L model's 18" disc wheels. Unique exterior features consist of Fender badges and chrome side mirror covers. The interior features a sunburst dashboard panel that pays homage to the Fender Stratocaster, a 400 watt premium audio system with nine speakers, an LCD screen, and a 10-channel amplifier.


title: Volkswagen Beetle (A5)

text: In January 2013, an official Xbox special edition was released. It uses the straight-five 2.5 L (170 hp) and comes in three different colors: Black, White and Silver all of them with the characteristic Xbox colors, panoramic sunroof, rear spoiler and 18" rims. This special edition was available only for the Mexican market.


title: Volkswagen Beetle (A5)

text: In February 2013 at the Chicago Auto Show, Volkswagen introduced the Beetle GSR Limited Edition. It is painted in yellow and black and only 3,500 will be produced, half of which will be sold in the United States, the other half in Europe. This special edition is modelled after the original 1973 special edition Super Beetle dubbed the GSR or, "Gelb Schwarz Renner", Yellow Black Racer in English. It was also the only Volkswagen that was offered with a factory boost gauge. The new GSR comes with Volkswagen's new 2.0l turbo four cylinder, this time making an extra 10 horsepower for a total of .


title: Volkswagen Beetle (A5)

text: Volkswagen has started production of a new R-Line Beetle. This new, limited edition trim level comes equipped with the new 210 hp gen3 turbo four, new front fascia and a metal dash plate finished off with 'R' badging all around. Along with increased performance, the new engine is expected to get about 8% greater fuel economy, or around 1–2 more miles per gallon. The engine will be fitted to all Volkswagens that currently use the gen2 2.0l turbo four.


title: Volkswagen Beetle (A5)

text: A version with a rugged off-road look called the 'Beetle Dune' went on sale in 2016. Although four-wheel drive is not available, the car's suspension has been raised by and an exclusive yellow colour is available as an option.


title: Volkswagen Beetle (A5)

text: The Beetle #PinkBeetle first began life as a concept car called the “Beetle Pink Edition”, but was renamed to Volkswagen Beetle #PinkBeetle upon production. It is version with pink accent and exclusive pink color, and was unveiled at the 2015 New York Auto Show alongside the Beetle Wave. It is the only model whose model name is a hashtag in it. The Beetle #PinkBeetle was produced from 2017 to early 2018.


title: Volkswagen Beetle (A5)

text: The Beetle Wave, also known as the Beetle Surf, is the concept stage of the Beetle Coast, with two prototypes being unveiled at the 2015 New York Auto Show and the 2015 Frankfurt Auto Show. It is a special version of the Beetle with 2 fully-wooden surfboards, an exclusive orange accent and “habanero orange” color, a houndstooth interior, real wood garnish for the dashboard, chrome mirror caps, 19-inch “Tornado”-design wheels, and Michigan license plates that read “NEW YORK CITY - BTL SRF”. The car pays homage to the Volkswagen Type 2 (T1), as both vehicles were designed for summertime enjoyment. Standard trim options include a soft convertible top.


title: Volkswagen Beetle (A5)

text: The Beetle Coast is the production version of the Beetle Wave concept car, officially released on January 1, 2018. It comes with 2 options: retractable hardtop and cabriolet. It is available in Deep Sea Teal, along with surf wood dash accents, a houndstooth interior (carried over from its concept stage) and a sunroof (only available on the Retractable Hardtop option) with disk-design hubcaps instead of the “Tornado”-design wheels from its concept. The Beetle Coast was designed to compete with the Honda Civic, Hyundai Elantra, and the Mazda3.


title: Volkswagen Beetle (A5)

text: A version with red, white and blue stripes running from front to back vertically and 53s on the doors, hood and trunk, made to resemble the paint job of Herbie The Love Bug, was sold exclusively in Spain.


title: Volkswagen Beetle (A5)

text: The Final Edition is the final version of the model sold in 2019 with two colors that were tributes to past Beetle models: Safari Uni Beige and Stonewashed Blue. Three other colors offered are Platinum Grey, Pure White, and Deep Black Pearl. The Final Edition came in both coupe and convertible body styles. There are two trims: SE and SEL.


title: Volkswagen Beetle (A5)

text: The previous generation New Beetle Convertible was sold alongside the Beetle Coupe (A5) in 2012. An all-new A5 based Beetle Convertible replaced the New Beetle Convertible for the 2013 model year.


title: Density of states

text: In solid state physics and condensed matter physics, the density of states (DOS) of a system describes the number of modes per unit frequency range. The density of states is defined as formula_1, where formula_2 is the number of states in the system of volume formula_3 whose energies lie in the range from formula_4 to formula_5. It is mathematically represented as a distribution by a probability density function, and it is generally an average over the space and time domains of the various states occupied by the system. The density of states is directly related to the dispersion relations of the properties of the system. High DOS at a specific energy level means that many states are available for occupation.


title: Density of states

text: Generally, the density of states of matter is continuous. In isolated systems however, such as atoms or molecules in the gas phase, the density distribution is discrete, like a spectral density. Local variations, most often due to distortions of the original system, are often referred to as local densities of states (LDOSs).


title: Density of states

text: In quantum mechanical systems, waves, or wave-like particles, can occupy modes or states with wavelengths and propagation directions dictated by the system. For example, in some systems, the interatomic spacing and the atomic charge of a material might allow only electrons of certain wavelengths to exist. In other systems, the crystalline structure of a material might allow waves to propagate in one direction, while suppressing wave propagation in another direction. Often, only specific states are permitted. Thus, it can happen that many states are available for occupation at a specific energy level, while no states are available at other energy levels .


title: Density of states

text: Looking at the density of states of electrons at the band edge between the valence and conduction bands in a semiconductor, for an electron in the conduction band, an increase of the electron energy makes more states available for occupation. Alternatively, the density of states is discontinuous for an interval of energy, which means that no states are available for electrons to occupy within the band gap of the material. This condition also means that an electron at the conduction band edge must lose at least the band gap energy of the material in order to transition to another state in the valence band.


title: Density of states

text: This determines if the material is an insulator or a metal in the dimension of the propagation. The result of the number of states in a band is also useful for predicting the conduction properties. For example, in a one dimensional crystalline structure an odd number of electrons per atom results in a half-filled top band; there are free electrons at the Fermi level resulting in a metal. On the other hand, an even number of electrons exactly fills a whole number of bands, leaving the rest empty. If then the Fermi level lies in an occupied band gap between the highest occupied state and the lowest empty state, the material will be an insulator or semiconductor.


title: Density of states

text: Depending on the quantum mechanical system, the density of states can be calculated for electrons, photons, or phonons, and can be given as a function of either energy or the wave vector "k". To convert between the DOS as a function of the energy and the DOS as a function of the wave vector, the system-specific energy dispersion relation between "E" and "k" must be known.


title: Density of states

text: In general, the topological properties of the system such as the band structure, have a major impact on the properties of the density of states. The most well-known systems, like neutronium in neutron stars and free electron gases in metals (examples of degenerate matter and a Fermi gas), have a 3-dimensional Euclidean topology. Less familiar systems, like two-dimensional electron gases (2DEG) in graphite layers and the quantum Hall effect system in MOSFET type devices, have a 2-dimensional Euclidean topology. Even less familiar are carbon nanotubes, the quantum wire and Luttinger liquid with their 1-dimensional topologies. Systems with 1D and 2D topologies are likely to become more common, assuming developments in nanotechnology and materials science proceed.


title: Density of states

text: Because the smallest allowed change of momentum formula_7 for a particle in a box of dimension formula_8 and length formula_9 is formula_10, the volume-related density of states for continuous energy levels is obtained in the limit formula_11 as


title: Density of states

text: For isotropic one-dimensional systems with parabolic energy dispersion, the density of states isformula_15. In two dimensions the density of states is a constant formula_16, while in three dimensions it becomes formula_17.


title: Density of states

text: Equivalently, the density of states can also be understood as the derivative of the microcanonical partition function formula_18 (that is, the total number of states with energy less than formula_4) with respect to the energy:


title: Density of states

text: Some condensed matter systems possess a structural symmetry on the microscopic scale which can be exploited to simplify calculation of their densities of states. In spherically symmetric systems, the integrals of functions are one-dimensional because all variables in the calculation depend only on the radial parameter of the dispersion relation. Fluids, glasses and amorphous solids are examples of a symmetric system whose dispersion relations have a rotational symmetry.


title: Density of states

text: Measurements on powders or polycrystalline samples require evaluation and calculation functions and integrals over the whole domain, most often a Brillouin zone, of the dispersion relations of the system of interest. Sometimes the symmetry of the system is high, which causes the shape of the functions describing the dispersion relations of the system to appear many times over the whole domain of the dispersion relation. In such cases the effort to calculate the DOS can be reduced by a great amount when the calculation is limited to a reduced zone or fundamental domain. The Brillouin zone of the face-centered cubic lattice (FCC) in the figure on the right has the 48-fold symmetry of the point group "O" with full octahedral symmetry. This configuration means that the integration over the whole domain of the Brillouin zone can be reduced to a 48-th part of the whole Brillouin zone. As a crystal structure periodic table shows, there are many elements with a FCC crystal structure, like diamond, silicon and platinum and their Brillouin zones and dispersion relations have this 48-fold symmetry. Two other familiar crystal structures are the body-centered cubic lattice (BCC) and hexagonal closed packed structures (HCP) with cubic and hexagonal lattices, respectively. The BCC structure has the 24-fold pyritohedral symmetry of the point group "T". The HCP structure has the 12-fold prismatic dihedral symmetry of the point group "D". A complete list of symmetry properties of a point group can be found in point group character tables.


title: Density of states

text: In general it is easier to calculate a DOS when the symmetry of the system is higher and the number of topological dimensions of the dispersion relation is lower. The DOS of dispersion relations with rotational symmetry can often be calculated analytically. This result is fortunate, since many materials of practical interest, such as steel and silicon, have high symmetry.


title: Density of states

text: In anisotropic condensed matter systems such as a single crystal of a compound, the density of states could be different in one crystallographic direction than in another. These causes the anisotropic density of states to be more difficult to visualize, and might require methods such as calculating the DOS for particular points or directions only, or calculating the projected density of states (PDOS) to a particular crystal orientation.


title: Density of states

text: The density of states is dependent upon the dimensional limits of the object itself. In a system described by three orthogonal parameters (3 Dimension), the units of DOS is EnergyVolume , in a two dimensional system, the units of DOS is EnergyArea , in a one dimensional system, the units of DOS is EnergyLength. The referenced volume is the volume of "k"-space; the space enclosed by the constant energy surface of the system derived through a dispersion relation that relates "E" to "k". An example of a 3-dimensional "k"-space is given in Fig. 1. It can be seen that the dimensionality of the system confines the momentum of particles inside the system.


title: Density of states

text: The calculation for DOS starts by counting the "N" allowed states at a certain "k" that are contained within inside the volume of the system. This procedure is done by differentiating the whole k-space volume formula_23 in n-dimensions at an arbitrary "k", with respect to "k". The volume, area or length in 3, 2 or 1-dimensional spherical "k"-spaces are expressed by


title: Density of states

text: for linear, disk and spherical symmetrical shaped functions in 1, 2 and 3-dimensional Euclidean "k"-spaces respectively.


title: Density of states

text: According to this scheme, the density of wave vector states "N" is, through differentiating formula_26 with respect to "k", expressed by


title: Density of states

text: formula_28 is the chemical potential (also denoted as E and called the Fermi level when "T"=0), formula_29 is the Boltzmann constant, and formula_30 is temperature. Fig. 4 illustrates how the product of the Fermi-Dirac distribution function and the three-dimensional density of states for a semiconductor can give insight to physical properties such as carrier concentration and Energy band gaps.


title: Density of states

text: Bose–Einstein statistics: The Bose–Einstein probability distribution function is used to find the probability that a boson occupies a specific quantum state in a system at thermal equilibrium. Bosons are particles which do not obey the Pauli exclusion principle (e.g. phonons and photons). The distribution function can be written as


title: Density of states

text: From these two distributions it is possible to calculate properties such as the internal energy formula_32, the number of particles formula_33, specific heat capacity formula_34, and thermal conductivity formula_7. The relationships between these properties and the product of the density of states and the probability distribution, denoting the density of states by formula_36 instead of formula_37, are given by


title: Density of states

text: The density of states appears in many areas of physics, and helps to explain a number of quantum mechanical phenomena.


title: Density of states

text: Calculating the density of states for small structures shows that the distribution of electrons changes as dimensionality is reduced. For quantum wires, the DOS for certain energies actually becomes higher than the DOS for bulk semiconductors, and for quantum dots the electrons become quantized to certain energies.


title: Density of states

text: The photon density of states can be manipulated by using periodic structures with length scales on the order of the wavelength of light. Some structures can completely inhibit the propagation of light of certain colors (energies), creating a photonic band gap: the DOS is zero for those photon energies. Other structures can inhibit the propagation of light only in certain directions to create mirrors, waveguides, and cavities. Such periodic structures are known as photonic crystals. In nanostructured media the concept of local density of states (LDOS) is often more relevant than that of DOS, as the DOS varies considerably from point to point.


title: Density of states

text: Interesting systems are in general complex, for instance compounds, biomolecules, polymers, etc. Because of the complexity of these systems the analytical calculation of the density of states is in most of the cases impossible. Computer simulations offer a set of algorithms to evaluate the density of states with a high accuracy. One of these algorithms is called the Wang and Landau algorithm.


title: Density of states

text: Within the Wang and Landau scheme any previous knowledge of the density of states is required. One proceeds as follows: the cost function (for example the energy) of the system is discretized. Each time the bin "i" is reached one updates


title: Density of states

text: where "f" is called the modification factor. As soon as each bin in the histogram is visited a certain number of times


title: Density of states

text: where "n" denotes the "n"-th update step. The simulation finishes when the modification factor is less than a certain threshold, for instance formula_45.


title: Density of states

text: The Wang and Landau algorithm has some advantages over other common algorithms such as multicanonical simulations and parallel tempering. For example, the density of states is obtained as the main product of the simulation. Additionally, Wang and Landau simulations are completely independent of the temperature. This feature allows to compute the density of states of systems with very rough energy landscape such as proteins.


title: Density of states

text: An important feature of the definition of the DOS is that it can be extended to any system. One of its properties are the translationally invariability which means that the density of the states is homogeneous and it's the same at each point of the system. But this is just a particular case and the LDOS gives a wider description with a heterogeneous density of states through the system.


title: Density of states

text: Local density of states (LDOS) describes a space-resolved density of states. In materials science, for example, this term is useful when interpreting the data from a scanning tunneling microscope (STM), since this method is capable of imaging electron densities of states with atomic resolution. According to crystal structure, this quantity can be predicted by computational methods, as for example with density functional theory.


title: Density of states

text: In a local density of states the contribution of each state is weighted by the density of its wave function at the point. formula_46 becomes formula_47


title: Density of states

text: the factor of formula_49 means that each state contributes more in the regions where the density is high. An average over formula_50 of this expression will restore the usual formula for a DOS. The LDOS is useful in inhomogeneous systems, where formula_47 contains more information than formula_52 alone.


title: Density of states

text: this is called the "spectral function" and it's a function with each wave function separately in its own variable. In more advanced theory it is connected with the Green's functions and provides a compact representation of some results such as optical absorption.


title: Density of states

text: LDOS can be used to gain profit into a solid-state device. For example, the figure on the right illustrates LDOS of a transistor as it turns on and off in a ballistic simulation. The LDOS has clear boundary in the source and drain, that corresponds to the location of band edge. In the channel, the DOS is increasing as gate voltage increase and potential barrier goes down.