|Writing system||Latin script|
|Type||Alphabetic and Logographic|
|Language of origin||Latin language|
|Time period||~-700 to present|
|Descendants|| • ₦|
|Other letters commonly used with||n(x), nh, ng, ny|
One of the most common hieroglyphs, snake, was used in Egyptian writing to stand for a sound like the English ⟨J⟩, because the Egyptian word for "snake" was djet. It is speculated by many that Semitic people working in Egypt adapted hieroglyphics to create the first alphabet, and that they used the same snake symbol to represent N, because their word for "snake" may have begun with that sound. However, the name for the letter in the Phoenician, Hebrew, Aramaic and Arabic alphabets is nun, which means "fish" in some of these languages. The sound value of the letter was /n/—as in Greek, Etruscan, Latin and modern languages.
⟨n⟩ represents a dental or alveolar nasal in virtually all languages that use the Latin alphabet, and in the International Phonetic Alphabet. A common digraph with ⟨n⟩ is ⟨ng⟩, which represents a velar nasal in a variety of languages, usually positioned word-finally in English. Often, before a velar plosive (as in ink or jungle), ⟨n⟩ alone represents a velar nasal. In Italian and French, ⟨gn⟩ represents a palatal nasal /ɲ/. The Portuguese and Vietnamese spelling for this sound is ⟨nh⟩, while Spanish, Breton, and a few other languages use the letter ⟨ñ⟩. In English, ⟨n⟩ is generally silent when it is preceded by an ⟨m⟩ at the end of words, as in hymn; however, it is pronounced in this combination when occurring word medially, as in hymnal.
|Unicode name||LATIN CAPITAL LETTER N||LATIN SMALL LETTER N|
|Numeric character reference||N||N||n||n|
|NATO phonetic||Morse code|
|Signal flag||Flag semaphore||American manual alphabet (ASL fingerspelling)||Braille |
Antigua and Barbuda ( (listen); an-TEE-g(w)ə ... bar-B(Y)OO-də) is a country in the West Indies in the Americas, lying between the Caribbean Sea and the Atlantic Ocean. It consists of two major islands, Antigua and Barbuda, and a number of smaller islands (including Great Bird, Green, Guiana, Long, Maiden and York Islands and further south, the island of Redonda). The permanent population numbers about 81,800 (at the 2011 Census) and the capital and largest port and city is St. John's on Antigua. Lying near each other (the main Barbuda airport is less than 0.5° of latitude, or 30 nautical miles, north of the main Antigua airport), Antigua and Barbuda are in the middle of the Leeward Islands, part of the Lesser Antilles, roughly at 17°N of the equator.
The island of Antigua was explored by Christopher Columbus in 1493 and named for the Church of Santa María La Antigua. Antigua was colonized by Britain in 1632; Barbuda island was first colonized in 1678. Antigua and Barbuda joined the West Indies Federation in 1958. With the breakup of the federation, it became one of the West Indies Associated States in 1967. Following by self-governing on its internal affairs, independence was granted from United Kingdom on 1 November 1981.
Antigua and Barbuda remains a member of the Commonwealth and Elizabeth II is the country's queen and head of state.Axl Rose
W. Axl Rose (born William Bruce Rose Jr.; raised as William Bruce Bailey; born February 6, 1962) is an American singer, songwriter, record producer and musician. He is the lead vocalist of the hard rock band Guns N' Roses, and has also been the band's sole constant member since its inception in 1985. In addition to Guns N' Roses, he also toured with Australian rock band AC/DC in 2016 during their Rock or Bust World Tour when Brian Johnson took a break due to hearing problems.
Rose has been named one of the greatest singers of all time by various media outlets, including Rolling Stone and NME.Born and raised in Lafayette, Indiana, Rose moved in the early 1980s to Los Angeles, where he became active in the local hard rock scene and joined several bands, including Hollywood Rose and L.A. Guns. In 1985, he co-founded Guns N' Roses, with whom he had great success and recognition in the late 1980s and early 1990s. Their first album, Appetite for Destruction (1987), has sold in excess of 30 million copies worldwide, and is the best-selling debut album of all time in the U.S. with 18 million units sold. Its full-length follow-ups, the twin albums Use Your Illusion I and Use Your Illusion II (1991), were also widely successful; they respectively debuted at No. 2 and No. 1 on the Billboard 200 and have sold a combined 35 million copies worldwide.After 1994, following the conclusion of their two-and-a-half-year Use Your Illusion Tour, Rose disappeared from public life for several years, while the band disintegrated due to personal and musical differences. As its sole remaining original member, he was able to continue working under the Guns N' Roses banner because he had legally obtained the band name. In 2001, he resurfaced with a new line-up of Guns N' Roses at Rock in Rio 3, and subsequently played periodic concert tours to promote the long-delayed Chinese Democracy (2008), which undersold the music industry's commercial expectations despite positive reviews upon its release. In 2012, Rose was inducted into the Rock and Roll Hall of Fame as a member of Guns N' Roses, though he declined to attend the event and requested exclusion from the Hall. In 2016, Rose partially reunited the "classic" lineup of Guns N' Roses and has since toured the world as part of the Not in This Lifetime... Tour. That same year, Rose also toured with AC/DC, filling in for Brian Johnson as the lead singer of the group and embarked on a world tour with them.Fibonacci number
In mathematics, the Fibonacci numbers, commonly denoted Fn form a sequence, called the Fibonacci sequence, such that each number is the sum of the two preceding ones, starting from 0 and 1. That is,
for n > 1.
One has F2 = 1. In some books, and particularly in old ones, F0, the "0" is omitted, and the Fibonacci sequence starts with F1 = F2 = 1. The beginning of the sequence is thus:
Fibonacci numbers are strongly related to the golden ratio: Binet's formula expresses the nth Fibonacci number in terms of n and the golden ratio, and implies that the ratio of two consecutive Fibonacci numbers tends to the golden ratio as n increases.
Fibonacci numbers are named after Italian mathematician Leonardo of Pisa, later known as Fibonacci. They appear to have first arisen as early as 200 BC in work by Pingala on enumerating possible patterns of poetry formed from syllables of two lengths. In his 1202 book Liber Abaci, Fibonacci introduced the sequence to Western European mathematics, although the sequence had been described earlier in Indian mathematics.
Fibonacci numbers appear unexpectedly often in mathematics, so much so that there is an entire journal dedicated to their study, the Fibonacci Quarterly. Applications of Fibonacci numbers include computer algorithms such as the Fibonacci search technique and the Fibonacci heap data structure, and graphs called Fibonacci cubes used for interconnecting parallel and distributed systems. They also appear in biological settings, such as branching in trees, the arrangement of leaves on a stem, the fruit sprouts of a pineapple, the flowering of an artichoke, an uncurling fern and the arrangement of a pine cone's bracts.
Fibonacci numbers are also closely related to Lucas numbers in that they form a complementary pair of Lucas sequences and . Lucas numbers are also intimately connected with the golden ratio.G20
The G20 (or Group of Twenty) is an international forum for the governments and central bank governors from 19 countries and the European Union. Founded in 1999 with the aim to discuss policy pertaining to the promotion of international financial stability, the G20 has expanded its agenda since 2008 and heads of government or heads of state, as well as finance ministers and foreign ministers, have periodically conferred at summits ever since. It seeks to address issues that go beyond the responsibilities of any one organization.Membership of the G20 consists of 19 individual countries plus the European Union (EU). The EU is represented by the European Commission and by the European Central Bank. Collectively, the G20 economies account for around 90% of the gross world product (GWP), 80% of world trade (or, if excluding EU intra-trade, 75%), two-thirds of the world population, and approximately half of the world land area.
With the G20 growing in stature after its inaugural leaders' summit in 2008, its leaders announced on 25 September 2009 that the group would replace the G8 as the main economic council of wealthy nations. Since its inception, the G20's membership policies have been criticized by numerous intellectuals, and its summits have been a focus for major protests by left-wing groups and anarchists.The heads of the G20 nations met semi-annually at G20 summits between 2009 and 2010. Since the November 2011 Cannes summit, all G20 summits have been held annually.Golden ratio
In mathematics, two quantities are in the golden ratio if their ratio is the same as the ratio of their sum to the larger of the two quantities. The figure on the right illustrates the geometric relationship. Expressed algebraically, for quantities a and b with a > b > 0,
where the Greek letter phi ( or ) represents the golden ratio. It is an irrational number with a value of:
The golden ratio is also called the golden mean or golden section (Latin: sectio aurea). Other names include extreme and mean ratio, medial section, divine proportion, divine section (Latin: sectio divina), golden proportion, golden cut, and golden number.
Mathematicians since Euclid have studied the properties of the golden ratio, including its appearance in the dimensions of a regular pentagon and in a golden rectangle, which may be cut into a square and a smaller rectangle with the same aspect ratio. The golden ratio has also been used to analyze the proportions of natural objects as well as man-made systems such as financial markets, in some cases based on dubious fits to data. The golden ratio appears in some patterns in nature, including the spiral arrangement of leaves and other plant parts.
Some twentieth-century artists and architects, including Le Corbusier and Salvador Dalí, have proportioned their works to approximate the golden ratio—especially in the form of the golden rectangle, in which the ratio of the longer side to the shorter is the golden ratio—believing this proportion to be aesthetically pleasing.Guns N' Roses
Guns N' Roses, often abbreviated as GNR, is an American hard rock band from Los Angeles, California, formed in 1985. When they signed to Geffen Records in 1986, the band comprised vocalist Axl Rose, lead guitarist Slash, rhythm guitarist Izzy Stradlin, bassist Duff McKagan, and drummer Steven Adler. The current lineup consists of Rose, Slash, McKagan, keyboardist Dizzy Reed, guitarist Richard Fortus, drummer Frank Ferrer and keyboardist Melissa Reese.
Guns N' Roses' debut album, Appetite for Destruction (1987), reached number one on the Billboard 200 a year after its release, on the strength of "Sweet Child o' Mine", the band's only single to reach number one on the Billboard Hot 100. The album has sold approximately 30 million copies worldwide, including 18 million units in the United States, making it the country's bestselling debut album and eleventh-bestselling album. Their next studio album, G N' R Lies (1988), reached number two on the Billboard 200. Use Your Illusion I and Use Your Illusion II, recorded simultaneously and released in 1991, debuted at number two and number one on the Billboard 200 respectively and have sold a combined 35 million copies worldwide, including 14 million units in the United States. "The Spaghetti Incident?" (1993), an album of covers, was the band's last studio album to feature Slash and McKagan.
Chinese Democracy (2008), Guns N' Roses' long-awaited sixth studio album, was released after more than a decade of work and several lineup changes. At an estimated $14 million in production costs, it is the most expensive rock album in history. It debuted at number three on the Billboard 200, but undersold industry expectations despite mostly positive critical reception. Slash and McKagan rejoined the band in 2016 for the Not in This Lifetime... Tour, which became the second-highest-grossing concert tour of all time, grossing over $562 million by December 2018.
In their early years, the band's hedonism and rebelliousness drew comparisons to the early Rolling Stones and earned them the nickname "the most dangerous band in the world." The band's classic lineup, along with later members Reed and drummer Matt Sorum, was inducted into the Rock and Roll Hall of Fame in 2012, its first year of eligibility. Guns N' Roses have sold more than 100 million records worldwide, including 45 million in the United States, making them the 41st-bestselling artist of all time.Leo Tolstoy
Count Lev Nikolayevich Tolstoy (; Russian: Лев Николаевич Толстой, tr. Lev Nikoláyevich Tolstóy; [lʲef nʲɪkɐˈlaɪvʲɪtɕ tɐlˈstoj] (listen); 9 September [O.S. 28 August] 1828 – 20 November [O.S. 7 November] 1910), usually referred to in English as Leo Tolstoy, was a Russian writer who is regarded as one of the greatest authors of all time.Born to an aristocratic Russian family in 1828, he is best known for the novels War and Peace (1869) and Anna Karenina (1877), often cited as pinnacles of realist fiction. He first achieved literary acclaim in his twenties with his semi-autobiographical trilogy, Childhood, Boyhood, and Youth (1852–1856), and Sevastopol Sketches (1855), based upon his experiences in the Crimean War. Tolstoy's fiction includes dozens of short stories and several novellas such as The Death of Ivan Ilyich (1886), Family Happiness (1859), and Hadji Murad (1912). He also wrote plays and numerous philosophical essays.
In the 1870s Tolstoy experienced a profound moral crisis, followed by what he regarded as an equally profound spiritual awakening, as outlined in his non-fiction work A Confession (1882). His literal interpretation of the ethical teachings of Jesus, centering on the Sermon on the Mount, caused him to become a fervent Christian anarchist and pacifist. Tolstoy's ideas on nonviolent resistance, expressed in such works as The Kingdom of God Is Within You (1894), were to have a profound impact on such pivotal 20th-century figures as Mohandas Karamchand Gandhi, and Martin Luther King, Jr. Tolstoy also became a dedicated advocate of Georgism, the economic philosophy of Henry George, which he incorporated into his writing, particularly Resurrection (1899).List of United States cities by population
The following is a list of the most populous incorporated places of the United States. As defined by the United States Census Bureau, an "incorporated place" includes a variety of designations, including city, town, village, borough, and municipality. A few exceptional census-designated places (CDPs) are also included in the Census Bureau's listing of incorporated places. Consolidated city-counties represent a distinct type of government that includes the entire population of a county, or county equivalent. Some consolidated city-counties, however, include multiple incorporated places. This list presents only that portion (or "balance") of such consolidated city-counties that are not a part of another incorporated place.
This list refers only to the population of individual municipalities within their defined limits; the populations of other municipalities considered suburbs of a central city are listed separately, and unincorporated areas within urban agglomerations are not included. Therefore, a different ranking is evident when considering U.S. metropolitan area populations.Methamphetamine
Methamphetamine (contracted from N-methylamphetamine) is a potent central nervous system (CNS) stimulant that is mainly used as a recreational drug and less commonly as a second-line treatment for attention deficit hyperactivity disorder and obesity. Methamphetamine was discovered in 1893 and exists as two enantiomers: levo-methamphetamine and dextro-methamphetamine. Methamphetamine properly refers to a specific chemical, the racemic free base, which is an equal mixture of levomethamphetamine and dextromethamphetamine in their pure amine forms. It is rarely prescribed over concerns involving human neurotoxicity and potential for recreational use as an aphrodisiac and euphoriant, among other concerns, as well as the availability of safer substitute drugs with comparable treatment efficacy. Dextromethamphetamine is a much stronger CNS stimulant than levomethamphetamine.
Both methamphetamine and dextromethamphetamine are illicitly trafficked and sold owing to their potential for recreational use. The highest prevalence of illegal methamphetamine use occurs in parts of Asia, Oceania, and in the United States, where racemic methamphetamine, levomethamphetamine, and dextromethamphetamine are classified as schedule II controlled substances. Levomethamphetamine is available as an over-the-counter (OTC) drug for use as an inhaled nasal decongestant in the United States. Internationally, the production, distribution, sale, and possession of methamphetamine is restricted or banned in many countries, due to its placement in schedule II of the United Nations Convention on Psychotropic Substances treaty. While dextromethamphetamine is a more potent drug, racemic methamphetamine is sometimes illicitly produced due to the relative ease of synthesis and limited availability of chemical precursors.
In low to moderate doses, methamphetamine can elevate mood, increase alertness, concentration and energy in fatigued individuals, reduce appetite, and promote weight loss. At relatively high doses, it can induce psychosis, breakdown of skeletal muscle, seizures and bleeding in the brain. Chronic high-dose use can precipitate unpredictable and rapid mood swings, stimulant psychosis (e.g., paranoia, hallucinations, delirium, and delusions) and violent behavior. Recreationally, methamphetamine's ability to increase energy has been reported to lift mood and increase sexual desire to such an extent that users are able to engage in sexual activity continuously for several days. Methamphetamine is known to possess a high addiction liability (i.e., a high likelihood that long-term or high dose use will lead to compulsive drug use) and high dependence liability (i.e. a high likelihood that withdrawal symptoms will occur when methamphetamine use ceases). Heavy recreational use of methamphetamine may lead to a post-acute-withdrawal syndrome, which can persist for months beyond the typical withdrawal period. Unlike amphetamine, methamphetamine is neurotoxic to human midbrain dopaminergic neurons. It has also been shown to damage serotonin neurons in the CNS. This damage includes adverse changes in brain structure and function, such as reductions in grey matter volume in several brain regions and adverse changes in markers of metabolic integrity.
Methamphetamine belongs to the substituted phenethylamine and substituted amphetamine chemical classes. It is related to the other dimethylphenethylamines as a positional isomer of these compounds, which share the common chemical formula: C10H15N1.N,N-Dimethyltryptamine
N,N-Dimethyltryptamine (DMT or N,N-DMT) is a chemical substance that occurs in many plants and animals and which is both a derivative and a structural analog of tryptamine. It can be consumed as a psychedelic drug and has historically been prepared by various cultures for ritual purposes as an entheogen. Rick Strassman labeled it "the spirit molecule". DMT is illegal in most countries.
DMT has a rapid onset, intense effects and a relatively short duration of action. For those reasons, DMT was known as the "businessman's trip" during the 1960s in the United States, as a user could access the full depth of a psychedelic experience in considerably less time than with other substances such as LSD or magic mushrooms. DMT can be inhaled, injected, vaporized or ingested, and its effects depend on the dose. When inhaled or injected, the effects last a short period of time: about 5 to 15 minutes. Effects can last 3 hours or more when orally ingested along with an MAOI, such as the ayahuasca brew of many native Amazonian tribes. DMT can produce vivid "projections" of mystical experiences involving euphoria and dynamic hallucinations of geometric forms.DMT is a functional analog of other psychedelic tryptamines such as 4-AcO-DMT, 5-MeO-DMT, 5-HO-DMT, psilocybin (4-PO-DMT), and psilocin (4-HO-DMT). The structure of DMT occurs within some important biomolecules like serotonin and melatonin, making them structural analogs of DMT.N. T. Rama Rao
Nandamuri Taraka Rama Rao (28 May 1923 – 18 January 1996), popularly known as NTR, was an Indian actor, producer, director, editor and politician who served as Chief Minister of Andhra Pradesh for seven years over three terms. He is widely regarded as one of the best actors of Indian cinema . NTR received three National Film Awards for co-producing Thodu Dongalu (1954) and Seetharama Kalyanam (1960) under National Art Theater, Madras, and for directing Varakatnam (1970). NTR has received the erstwhile Rashtrapati Awards for his performance(s) in the films Raju Peda (1954) and Lava Kusa (1963). He garnered the Nandi Award for Best Actor for Kodalu Diddina Kapuram in 1970, and the Inaugural Filmfare Award for Best Actor – Telugu in 1972 for Badi Panthulu.NTR made his debut as an actor in a Telugu social film Mana Desam, directed by L. V. Prasad in 1949. He gained popularity in the 1950s when he became well known for his portrayals of Hindu deities, especially Krishna and Rama, roles which have made him a "messiah of the masses". He later became known for portraying antagonistic characters and Robin Hood-esque hero characters in films. In total, he starred in 300 films, and has become one of the most prominent figures in the history of Telugu cinema. He was voted "Greatest Indian Actor of All Time" in a CNN-IBN national poll conducted in 2013 on the occasion of the Centenary of Indian Cinema.He starred in such films as Patala Bhairavi (1951), which premiered at the first India International Film Festival, held in Mumbai on 24 January 1952, Malliswari (1951), premiered at Asia Pacific Film Festival, the enduring classics Mayabazar (1957) and Nartanasala (1963), featured at Afro Asian film festival in Jakarta. All the four films were included in CNN-IBN's list of "Hundred greatest Indian films of all time".He co-produced Ummadi Kutumbam, nominated by Film Federation of India as one of its entries to the 1968 Moscow Film Festival.
Besides Telugu, he has also acted in a few Tamil films. Widely recognised for his portrayal of mythological characters, NTR was one of the leading method actors of Indian cinema, He was referred to in the media as Viswa Vikhyatha Nata Sarvabhouma. He was awarded the Padma Shri by the Government of India in 1968, recognizing his contribution to Indian cinema.
After his career in films, NTR entered politics. He founded the Telugu Desam Party (TDP) in 1982 and served three tumultuous terms as Chief Minister of Andhra Pradesh between 1983 and 1995. He was known as an advocate of Andhra Pradesh's distinct cultural identity, distinguishing it from the erstwhile Madras State with which it was often associated. At the national level, he was instrumental in the formation of the National Front, a coalition of non-Congress parties which governed India from 1989 until 1990.NCIS (TV series)
NCIS is an American action police procedural television series, revolving around a fictional team of special agents from the Naval Criminal Investigative Service, which investigates crimes involving the U.S. Navy and Marine Corps. The concept and characters were initially introduced in two episodes of the CBS series JAG (season eight episodes 20 and 21: "Ice Queen" and "Meltdown"). The show, a spin-off from JAG, premiered on September 23, 2003, on CBS. To date it has aired fifteen full seasons and has gone into broadcast syndication on the USA Network. Donald P. Bellisario and Don McGill are co-creators and executive producers of the premiere member of the NCIS franchise. It is the second-longest-running scripted, non-animated U.S. primetime TV series currently airing, surpassed only by Law & Order: Special Victims Unit (1999–present), and is the 7th-longest-running scripted U.S. primetime TV series overall.
NCIS was originally referred to as Navy NCIS during season one; "Navy" was later dropped from the title as it was redundant (the "N" in "NCIS" stands for "Naval"). In season six, a two-part episode led to a spin-off series, NCIS: Los Angeles. A two-part episode during the eleventh season led to a second spin-off series, NCIS: New Orleans. While initially slow in the ratings, barely cracking the Top 30 in the first two seasons, the third season showed progress, consistently ranking in the top 20, and by its sixth season, it became a top five hit, having remained there since. In 2011, NCIS was voted America's favorite television show in an online Harris Poll. The series finished its tenth season as the most-watched television series in the U.S. during the 2012–13 TV season. On April 13, 2018, NCIS was renewed for a sixteenth season, that premiered on September 25, 2018. Diona Reasonover joined the main cast in Season 16, following the departures of Duane Henry and Pauley Perrette.NSYNC
NSYNC (, ; also stylized as *NSYNC or 'N Sync) was an American boy band formed in Orlando, Florida, in 1995 and launched in Germany by BMG Ariola Munich. NSYNC consisted of Justin Timberlake, JC Chasez, Chris Kirkpatrick, Joey Fatone, and Lance Bass. After heavily publicized legal battles with their former manager Lou Pearlman and former record label Bertelsmann Music Group, the group's second album, No Strings Attached (2000), sold over one million copies in one day and 2.42 million copies in one week, which was a record for over fifteen years. Among the group's singles, "I Want You Back", "Bye Bye Bye", "This I Promise You", "Girlfriend", "Pop" and "It's Gonna Be Me" reached the top 10 in several international charts, with the latter being a US Billboard Hot 100 number one. In addition to a host of Grammy Award nominations, NSYNC has performed at the World Series, the Super Bowl and the Olympic Games, and sang or recorded with Elton John, Stevie Wonder, Michael Jackson, Janet Jackson, Britney Spears, Phil Collins, Celine Dion, Aerosmith, Nelly, Left Eye, Mary J. Blige, country music supergroup Alabama, and Gloria Estefan.
Although NSYNC announced the start of a "temporary hiatus" in early 2002, the band has not recorded new material since then. In 2007, Lance Bass confirmed that the group had "definitely broken up". The band completed five nationwide concert tours and has sold between 50 and 70 million records, becoming the fifth-best-selling boy band in history. Rolling Stone recognized their instant success as one of the Top 25 Teen Idol Breakout Moments of all time. Justin Timberlake went on to become one of the world's best-selling music artists, with more than 32 million albums and 56 million singles sold throughout his solo career.Nitrogen
Nitrogen is a chemical element with symbol N and atomic number 7. It was first discovered and isolated by Scottish physician Daniel Rutherford in 1772. Although Carl Wilhelm Scheele and Henry Cavendish had independently done so at about the same time, Rutherford is generally accorded the credit because his work was published first. The name nitrogène was suggested by French chemist Jean-Antoine-Claude Chaptal in 1790, when it was found that nitrogen was present in nitric acid and nitrates. Antoine Lavoisier suggested instead the name azote, from the Greek ἀζωτικός "no life", as it is an asphyxiant gas; this name is instead used in many languages, such as French, Russian, and Turkish, and appears in the English names of some nitrogen compounds such as hydrazine, azides and azo compounds.
Nitrogen is the lightest member of group 15 of the periodic table, often called the pnictogens. The name comes from the Greek πνίγειν "to choke", directly referencing nitrogen's asphyxiating properties. It is a common element in the universe, estimated at about seventh in total abundance in the Milky Way and the Solar System. At standard temperature and pressure, two atoms of the element bind to form dinitrogen, a colourless and odorless diatomic gas with the formula N2. Dinitrogen forms about 78% of Earth's atmosphere, making it the most abundant uncombined element. Nitrogen occurs in all organisms, primarily in amino acids (and thus proteins), in the nucleic acids (DNA and RNA) and in the energy transfer molecule adenosine triphosphate. The human body contains about 3% nitrogen by mass, the fourth most abundant element in the body after oxygen, carbon, and hydrogen. The nitrogen cycle describes movement of the element from the air, into the biosphere and organic compounds, then back into the atmosphere.
Many industrially important compounds, such as ammonia, nitric acid, organic nitrates (propellants and explosives), and cyanides, contain nitrogen. The extremely strong triple bond in elemental nitrogen (N≡N), the second strongest bond in any diatomic molecule after carbon monoxide (CO), dominates nitrogen chemistry. This causes difficulty for both organisms and industry in converting N2 into useful compounds, but at the same time means that burning, exploding, or decomposing nitrogen compounds to form nitrogen gas releases large amounts of often useful energy. Synthetically produced ammonia and nitrates are key industrial fertilisers, and fertiliser nitrates are key pollutants in the eutrophication of water systems.
Apart from its use in fertilisers and energy-stores, nitrogen is a constituent of organic compounds as diverse as Kevlar used in high-strength fabric and cyanoacrylate used in superglue. Nitrogen is a constituent of every major pharmacological drug class, including antibiotics. Many drugs are mimics or prodrugs of natural nitrogen-containing signal molecules: for example, the organic nitrates nitroglycerin and nitroprusside control blood pressure by metabolizing into nitric oxide. Many notable nitrogen-containing drugs, such as the natural caffeine and morphine or the synthetic amphetamines, act on receptors of animal neurotransmitters.Normal distribution
In probability theory, the normal (or Gaussian or Gauss or Laplace–Gauss) distribution is a very common continuous probability distribution. Normal distributions are important in statistics and are often used in the natural and social sciences to represent real-valued random variables whose distributions are not known. A random variable with a Gaussian distribution is said to be normally distributed and is called a normal deviate.
The normal distribution is useful because of the central limit theorem. In its most general form, under some conditions (which include finite variance), it states that averages of samples of observations of random variables independently drawn from independent distributions converge in distribution to the normal, that is, they become normally distributed when the number of observations is sufficiently large. Physical quantities that are expected to be the sum of many independent processes (such as measurement errors) often have distributions that are nearly normal. Moreover, many results and methods (such as propagation of uncertainty and least squares parameter fitting) can be derived analytically in explicit form when the relevant variables are normally distributed.
The normal distribution is sometimes informally called the bell curve. However, many other distributions are bell-shaped (such as the Cauchy, Student's t, and logistic distributions).
The probability density of the normal distribution is
A prime number (or a prime) is a natural number greater than 1 that cannot be formed by multiplying two smaller natural numbers. A natural number greater than 1 that is not prime is called a composite number. For example, 5 is prime because the only ways of writing it as a product, 1 × 5 or 5 × 1, involve 5 itself. However, 6 is composite because it is the product of two numbers (2 × 3) that are both smaller than 6. Primes are central in number theory because of the fundamental theorem of arithmetic: every natural number greater than 1 is either a prime itself or can be factorized as a product of primes that is unique up to their order.
The property of being prime is called primality. A simple but slow method of checking the primality of a given number , called trial division, tests whether is a multiple of any integer between 2 and . Faster algorithms include the Miller–Rabin primality test, which is fast but has a small chance of error, and the AKS primality test, which always produces the correct answer in polynomial time but is too slow to be practical. Particularly fast methods are available for numbers of special forms, such as Mersenne numbers. As of December 2018[update] the largest known prime number has 24,862,048 decimal digits.
There are infinitely many primes, as demonstrated by Euclid around 300 BC. No known simple formula separates prime numbers from composite numbers. However, the distribution of primes within the natural numbers in the large can be statistically modelled. The first result in that direction is the prime number theorem, proven at the end of the 19th century, which says that the probability of a randomly chosen number being prime is inversely proportional to its number of digits, that is, to its logarithm.
Several historical questions regarding prime numbers are still unsolved. These include Goldbach's conjecture, that every even integer greater than 2 can be expressed as the sum of two primes, and the twin prime conjecture, that there are infinitely many pairs of primes having just one even number between them. Such questions spurred the development of various branches of number theory, focusing on analytic or algebraic aspects of numbers. Primes are used in several routines in information technology, such as public-key cryptography, which relies on the difficulty of factoring large numbers into their prime factors. In abstract algebra, objects that behave in a generalized way like prime numbers include prime elements and prime ideals.Rock and Roll Hall of Fame
The Rock and Roll Hall of Fame, located on the shore of Lake Erie in downtown Cleveland, Ohio, recognizes and archives the history of the best-known and most influential artists, producers, engineers, and other notable figures who have had some major influence on the development of rock and roll. The Rock and Roll Hall of Fame Foundation was established on April 20, 1983, by Atlantic Records founder and chairman Ahmet Ertegun. In 1986, Cleveland was chosen as the Hall of Fame's permanent home.Rock and roll
Rock and roll (often written as rock & roll or rock 'n' roll) is a genre of popular music that originated and evolved in the United States during the late 1940s and early 1950s from musical styles such as gospel, jump blues, jazz, boogie woogie, and rhythm and blues, along with country music. While elements of what was to become rock and roll can be heard in blues records from the 1920s and in country records of the 1930s, the genre did not acquire its name until 1954.According to Greg Kot, "rock and roll" refers to a style of popular music originating in the U.S. in the 1950s prior to its development by the mid-1960s into "the more encompassing international style known as rock music, though the latter also continued to be known as rock and roll." For the purpose of differentiation, this article deals with the first definition.
In the earliest rock and roll styles, either the piano or saxophone was typically the lead instrument, but these instruments were generally replaced or supplemented by guitar in the middle to late 1950s. The beat is essentially a dance rhythm with an accentuated backbeat, which is almost always provided by a snare drum. Classic rock and roll is usually played with one or two electric guitars (one lead, one rhythm), a double bass or string bass or (after the mid-1950s) an electric bass guitar, and a drum kit.Beyond simply a musical style, rock and roll, as seen in movies, in fan magazines, and on television, influenced lifestyles, fashion, attitudes, and language. In addition, rock and roll may have contributed to the civil rights movement because both African-American and white American teenagers enjoyed the music. It went on to spawn various genres, often without the initially characteristic backbeat, that are now more commonly called simply "rock music" or "rock".Standard deviation
In statistics, the standard deviation (SD, also represented by the lower case Greek letter sigma σ or the Latin letter s) is a measure that is used to quantify the amount of variation or dispersion of a set of data values. A low standard deviation indicates that the data points tend to be close to the mean (also called the expected value) of the set, while a high standard deviation indicates that the data points are spread out over a wider range of values.
The standard deviation of a random variable, statistical population, data set, or probability distribution is the square root of its variance. It is algebraically simpler, though in practice less robust, than the average absolute deviation.
A useful property of the standard deviation is that, unlike the variance, it is expressed in the same units as the data.
In addition to expressing the variability of a population, the standard deviation is commonly used to measure confidence in statistical conclusions. For example, the margin of error in polling data is determined by calculating the expected standard deviation in the results if the same poll were to be conducted multiple times. This derivation of a standard deviation is often called the "standard error" of the estimate or "standard error of the mean" when referring to a mean. It is computed as the standard deviation of all the means that would be computed from that population if an infinite number of samples were drawn and a mean for each sample were computed.
It is very important to note that the standard deviation of a population and the standard error of a statistic derived from that population (such as the mean) are quite different but related (related by the inverse of the square root of the number of observations). The reported margin of error of a poll is computed from the standard error of the mean (or alternatively from the product of the standard deviation of the population and the inverse of the square root of the sample size, which is the same thing) and is typically about twice the standard deviation—the half-width of a 95 percent confidence interval.
In science, many researchers report the standard deviation of experimental data, and only effects that fall much farther than two standard deviations away from what would have been expected are considered statistically significant—normal random error or variation in the measurements is in this way distinguished from likely genuine effects or associations. The standard deviation is also important in finance, where the standard deviation on the rate of return on an investment is a measure of the volatility of the investment.
When only a sample of data from a population is available, the term standard deviation of the sample or sample standard deviation can refer to either the above-mentioned quantity as applied to those data or to a modified quantity that is an unbiased estimate of the population standard deviation (the standard deviation of the entire population).Variance
In probability theory and statistics, variance is the expectation of the squared deviation of a random variable from its mean. Informally, it measures how far a set of (random) numbers are spread out from their average value. Variance has a central role in statistics, where some ideas that use it include descriptive statistics, statistical inference, hypothesis testing, goodness of fit, and Monte Carlo sampling. Variance is an important tool in the sciences, where statistical analysis of data is common. The variance is the square of the standard deviation, the second central moment of a distribution, and the covariance of the random variable with itself, and it is often represented by , , or .