Russians are an East Slavic ethnic group and nation native to European Russia and other parts of Eastern Europe. The majority of ethnic Russians live in the Russian Federation, but notable minorities exist in other former Soviet states such as Belarus, Moldova and the Baltic states. A large Russian diaspora has developed all over the world, with notable numbers in the United States, Germany and Canada; the culture of the ethnic Russian people has a long tradition and it is a foundation for the modern culture of the whole of Russia. The Russian language was the language of ethnic Russians, they are Orthodox Christians by religion. The ethnic Russians formed from East Slavic tribes and their cultural ancestry is based in Kievan Rus'; the Russian word for ethnic Russians is derived from the people of Rus' and the territory of Rus'. The Russians share many historical and cultural traits with other European peoples, with other East Slavic ethnic groups Belarusians and Ukrainians. Many ethnic groups had a common history within the former Soviet Union and Russian Empire, influential in the spreading of Russian culture and language.

The Russian language is official in Russia, Kazakhstan and Tajikistan, is spoken as a secondary language in many former Soviet states. The ethnic Russians make up the largest of the 194 ethnic groups who live in Russia, according to the 2010 census; some 80.90% of the population identified voluntarily as ethnically Russian. The Constitution declares Russia to be a multinational state and it named the "multinational people of Russia" as a sovereign nation; the Russian word used for citizens of Russia is different from the word for ethnic Russian. The Tsardom of Russia became a multi-ethnic state in the 16th century in its imperial phase; the number of ethnic Russians living outside the Russian Federation is estimated at between 20 and 30 million people. Two Russian words are translated into English as "Russians". One is "русские", which most means "ethnic Russians". Another is "россияне", which means "citizens of Russia"; the former word refers to ethnic Russians, regardless of what country they live in or whether they hold Russian citizenship.

Under certain circumstances, this term may or may not extend to denote members of other Russian-speaking ethnic groups from Russia, or from the former Soviet Union. The latter word refers to all people holding citizenship of Russia, regardless of their ethnicity, does not include ethnic Russians living outside Russia. Translations into other languages do not distinguish these two groups; the name of the Russians derives from the Rus' people. According to the most prevalent theory, the name Rus', like the Finnish name for Sweden, is derived from an Old Norse term for "the men who row" as rowing was the main method of navigating the rivers of Eastern Europe, it could be associated to the Swedish coastal area of Roslagen or Roden, as it was known in earlier times. The name Rus' would have the same origin as the Finnish and Estonian names for Sweden: Ruotsi and Rootsi. Although Russian history and culture is shaped by Germanic people such as the Vikings, there are theories that Rus' is of a non-Germanic origin.

According to the historian Lydia Groth, Roslagen in IX—XII centuries was unsuitable for life, as it was under water at a depth of 6–7 meters. Furthermore, the name Roslagen was first documented only in 1493. According to other theories the name Rus' is derived from Proto-Slavic *roud-s-ь, connected with red color or from Indo-Iranian; until the 1917 revolution, Russian authorities never called the people "Russians", referring to them instead as "Great Russians," a part of "Russians". The modern Russians formed from two groups of East Slavic tribes: Northern and Southern; these tribes included the Krivichs, Ilmen Slavs, Radimichs and Severians. Genetic studies show that modern Russians do not differ from Belarusians and Ukrainians; some ethnographers, like Dmitry Konstantinovich Zelenin, affirm that Russians are more similar to Belarusians and to Ukrainians than southern Russians are to northern Russians. Russians in northern European Russia share moderate genetic similarities with Finnic peoples, who lived in modern north-central European Russia and were assimilated by the Slavs as the Slavs migrated northeastwards.

Such Finnic peoples included the Merya and the Muromians. The territory of Russia has been inhabited since 2nd Millennium BCE by Indo-European, Ural-Altaic, various other peoples. Slavic people are native to the western part of Russia. Outside archaeological remains, little is known about the predecessors to Russians in general prior to 859 AD, when the Primary Chronicle starts its records. By 600 AD, the Slavs are believed to have split linguistically into southern and eastern branches; the eastern branch settled between the Southern Bug and the Dnieper rivers in present-day Ukraine.


Citilink is a low-cost airline headquartered in Jakarta, Indonesia. It was established in 2001 as a low-cost brand of Garuda Indonesia, set up to operate shuttle services between Indonesian cities. Since 30 July 2012, Citilink has operated as a separate subsidiary of Garuda Indonesia, operating with its own callsign, airline codes and uniform, its main base is Soekarno -- Juanda International Airport. Garuda Indonesia established Citilink as a low-cost brand in 2001 and operations commenced on 16 July that year with two Fokker F28 Fellowships transferred from the mainline fleet. Initial operations were from Surabaya on the island of Java to destinations not served by Garuda Indonesia's mainline fleet: Yogyakarta. By the end of 2001 Garuda had transferred five F28s to Citilink. In 2004 Citilink was serving ten destinations and Garuda began to replace the F28s with Boeing 737-300s. In 2008 Garuda temporarily suspended operations of Citilink, relaunching the brand in January 2009 after replacing the remaining Fokker F28s with more modern aircraft.

In July 2010 Citilink operations were being conducted by two Boeing 737-300s and a Boeing 737-400. In May 2011 Garuda announced plans for a spin-off of Citilink; the new business plan was for Citilink to become a separate business entity in the first quarter of 2012 with a full brand overhaul for the airline, including a new livery design. An integral part of this plan was for Citilink to secure 25 new Airbus A320s and utilising these new and more economical aircraft to expand into a significant regional low-cost carrier with the anticipation that by 2015, Citilink would contribute 30 percent of Garuda Indonesia's revenue. After obtaining an Air Operator's Certificate in August 2012, Citilink had carried 8 million passengers by the end of 2013 and was running at a load factor of 85 percent and an On Time Arrival rate of 87 percent. In May 2015 the airline's fleet consisted of four Boeing 737-300s, four Boeing 737-500s and thirty-four Airbus A320s; as of December 2019, Citilink serves Indonesian domestic destinations.

The order consisted of 15 Airbus A320s and 10 Airbus A320neos, with five aircraft expected to be delivered each year between 2014 and 2018. The fleet upgrade program was valued at around $2.13 billion. By late 2011, Garuda Indonesia was seeking more used A320s in preparation for the launch of proposed international Citilink services in 2012. In December 2012, Citilink placed an order for 25 ATR 72-600s with options for 25 more; this was Citilink's first direct order to a manufacturer. A direct order for 25 additional A320neos followed in January 2013, bringing up the total order to 35. Citilink's first A320, a second-hand aircraft, arrived in late June 2011 and entered into service on 16 September 2011, linking Jakarta with Balikpapan and Medan. Citilink aircraft cabins have standard configuration of 180 seats. In July 2018, Citilink introduced. Seats on the first five rows and emergency window exit rows are named green seats, while the rest are named regular seats. Passengers wanting to book or request a green seat or specific regular seat during booking or check-in will be charged for a certain fee.

Additional benefits include free snacks and insurance. On 16 January 2019, Citilink became the first Low Cost Carrier in the Asia Pacific region to offer Wi-Fi at 35,000 feet above ground for free using GX Aviation Systems; the first flight with the connectivity feature flew flight number QG684 on the Jakarta to Denpasar route. On 28 December 2016, a video taken by a passenger aboard Citilink Flight 800, a flight from Juanda International Airport in Surabaya to Soekarno-Hatta International Airport in Jakarta went viral after it purportedly showed a drunk pilot making a "bizarre announcement" before takeoff. Several passengers reported the incident to the airline's headquarters; the crew of the flight removed the drunk pilot from the cockpit. Due to the incident, the flight was delayed for an hour. Citilink took action by sacking the pilot involved in the incident and issuing letters of apology to affected passengers; the Indonesian Transport Ministry apologized publicly to the Indonesian people due to the incident.

The ministry added that the pilot had undergone drug testing, conducted by the Indonesian National Narcotic Agency. Another video, captured from cameras at the airport security checkpoint surfaced and went viral; the video showed the drunk pilot becoming jittery and nearly losing his balance during the security check. Police investigated the video, resulting in the Indonesian Transport Ministry sending Citilink its first warning. In the aftermath of the incident, the CEO of Citilink, Albert Burhan, resigned; the operational director of Citilink, Hadinoto Soedigno resigned in response to the incident. Garuda Indonesia List of airlines of Indonesia List of airports in Indonesia Aviation in Indonesia Transport in Indonesia Official website

Greek letters used in mathematics, science, and engineering

Greek letters are used in mathematics, science and other areas where mathematical notation is used as symbols for constants, special functions, conventionally for variables representing certain quantities. In these contexts, the capital letters and the small letters represent distinct and unrelated entities; those Greek letters which have the same form as Latin letters are used: capital A, B, E, Z, H, I, K, M, N, O, P, T, Y, X. Small ι, ο and υ are rarely used, since they resemble the Latin letters i, o and u. Sometimes font variants of Greek letters are used as distinct symbols in mathematics, in particular for ε/ϵ and π/ϖ; the archaic letter digamma is sometimes used. The Bayer designation naming scheme for stars uses the first Greek letter, α, for the brightest star in each constellation, runs through the alphabet before switching to Latin letters. In mathematical finance, the Greeks are the variables denoted by Greek letters used to describe the risk of certain investments; the Greek letter forms used in mathematics are different from those used in Greek-language text: they are designed to be used in isolation, not connected to other letters, some use variant forms which are not used in current Greek typography.

The OpenType font format has the feature tag'mgrk' "Mathematical Greek" to identify a glyph as representing a Greek letter to be used in mathematical contexts. The table below shows a comparison of Greek letters rendered in TeX and HTML; the font used in the TeX rendering is an italic style. This is in line with the convention; as Greek letters are more than not used as variables in mathematical formulas, a Greek letter appearing similar to the TeX rendering is more to be encountered in works involving mathematics. Α represents: the first angle in a triangle, opposite the side A the statistical significance of a result the false positive rate in statistics the fine structure constant in physics the angle of attack of an aircraft an alpha particle angular acceleration in physics the linear thermal expansion coefficient the thermal diffusivity In organic chemistry the α-carbon is the backbone carbon next to the carbonyl carbon, most for amino acids right ascension in astronomy the brightest star in a constellation Iron ferrite and numerous phases within materials science the return in excess of the compensation for the risk borne in investment the α-conversion in lambda calculus the independence number of a graph Β represents the beta function β represents: the thermodynamic beta, equal to −1, where kB is Boltzmann's constant and T is the absolute temperature.

The second angle in a triangle, opposite the side B the standardized regression coefficient for predictor or independent variables in linear regression the ratio of collector current to base current in a bipolar junction transistor in electronics the false negative rate in statistics the beta coefficient, the non-diversifiable risk, of an asset in mathematical finance the sideslip angle of an airplane a beta particle the beta brain wave in brain or cognitive sciences ecliptic latitude in astronomy The ratio of plasma pressure to magnetic pressure in plasma physics β-reduction in lambda calculus The ratio of the velocity of an object to the speed of light as used in the Lorentz factor Γ represents: the circulation in fluid dynamics the reflection coefficient of a transmission or telecommunication line. The confinement factor of an optical mode in a waveguide the gamma function, a generalization of the factorial the upper incomplete gamma function the modular group, the group of fractional linear transformations the gamma distribution, a continuous probability distribution defined using the gamma function second-order sensitivity to price in mathematical finance the Christoffel symbols of the second kind the stack alphabet in the formal definition of a pushdown automaton γ represents: the specific weight of substances the lower incomplete gamma function the third angle in a triangle, opposite the side C the Euler–Mascheroni constant in mathematics gamma rays and the photon the heat capacity ratio in thermodynamics the Lorentz factor in special relativity Δ represents: a finite difference a difference operator a symmetric difference the Laplace operator the angle that subtends the arc of a circular curve in surveying the maximum degree of any vertex in a given graph sensitivity to price in mathematical finance the discriminant in the quadratic formula which determines the nature of the roots δ represents: percent error a variation in the calculus of variations the Kronecker delta function the Feigenbaum constant the force of interest in mathematical finance the Dirac delta function the receptor which enkephalins have the highest affinity for in pharmacology the Skorokhod integral in Malliavin calculus, a subfield of stochastic analysis the minimum degree of any vertex in a given graph a partial charge.

Δ− represents a negative partial charge, δ+ represents a positive partial charge chemistry the Chemical shift of an atomic nucleus in NMR spectroscopy. For protons, this is relative to tetramethylsilane = 0. Stable isotope compositions declination in astronomy noncentrality measure in statistics Not to be confused with ∂, based on the Latin letter d but called a "script delta." Ε represents: a small positive quantity.