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Talk:Tritium

Mystery reactions

 * [tritium is produced] by D(n,gamma)T) and 10B(n,t)8Be

I have no idea what this is supposed to mean; presumably it's some abbreviated description of nuclear reactions, but it's pretty impenetrable. If someone can clarify this, it can go back in. --Andrew 04:07, Apr 20, 2005 (UTC)

 * This is shorthand for nuclear bombardments
 * D(n,gamma)T means that Deuterium is bombarded with a neutron and releases gamma rays to become Tritium. 10B(n,t)8Be means that Boron-10 is bombarded with a neutron and releases a Tritium atom to become Beryllium-8. Both of these reactions produce Tritium. — oo64eva (AJ) (U @ 04:18, Apr 20, 2005 (UTC)

skin health risk
I am confused by this excerpt "it is not dangerous externally (its beta particles are unable to penetrate the skin), but it can be a radiation hazar when... absorbed through the skin." Jawz101 (talk) 18:15, 1 November 2020 (UTC)

 * Beta particles (electrons) can't penetrate the skin, but if a beta source was absorbed into your body, the beta particles could damage the DNA inside your body. Does this answer your question? Graystormmmmmmmmmmmmmmmmmmm 16:41, 28 July 2022 (UTC)

Ambiguous
"The nucleus of tritium (t, sometimes called a triton) contains one proton and two neutrons, whereas the nucleus of the common isotope hydrogen-1 (protium) contains just one proton, and that of hydrogen-2 (deuterium) contains one proton and one neutron."

This is ambiguous. I think it should read "just one proton and no neutrons" ... at least that's the way I can read it relating it to the previous phrase. WithGLEE (talk) 16:20, 15 August 2022 (UTC)

Reaction of a neutron with lithium-6
Can someone explain why when one hits lithium-6 with neurons it gives helium and tritium instead of giving lithim-7, which is at a lower energy? Eric Kvaalen (talk) 15:56, 16 October 2022 (UTC)

 * This is due to the fact that lithium-6 has a relatively low nuclear binding energy of ~5.6 MeV/nucleon, though the exact mechanism would also depend on the energy (temperature) of the incident neutron. If a neutron collides with lithium-6 and has a high enough "temperature" such that this binding energy is exceeded, the collision has a higher probability of inducing fission into lighter nuclei rather than fusion into lithium-7, so the neutron-capture cross section drops. Additionally, helium-4 is very stable, while lithium-7 is also fragile, and such nuclear processes tend to favor formation of more tightly bound and/or magic nuclei. This is also the reason why lithium is present in brown dwarfs but is destroyed in main sequence stars; the temperature inside main sequence stars is high enough such that collisions of neutrons with lithium cause it to be destroyed faster than it is created. Complex / Rational  22:28, 16 October 2022 (UTC)

 * Thanks for the reply. If I understand you correctly, you're saying that a good portion of the neutrons are absorbed, giving $7$Li, and that the amount depends on the energy of the neutron. That seems a bit strange, since I've never heard anyone talk about that in the context of blanketing a fusion reactor in order to create tritium. Can you give a reference so we can put that into the article? Also, I don't understand what you say about the helium being very stable andn the $7$Li being fragile. As I said, $7$Li is more stable (lower energy) than the combination of a helium and a tritium. Isn't that what counts in the end? Eric Kvaalen (talk) 10:50, 17 October 2022 (UTC)

 * By "stable", I was referring to binding energy, and the fact that 4He is also a doubly magic nucleus – although the 7Li nucleus is stable, the required energy to break it apart is much less than for 4He. Indeed, the absorption cross section is dependent on energy, though I'm not very familiar with the concept of "blanketing" a fusion reactor.
 * One article describing this reaction and the production of tritium is – it specifically describes the reaction 6Li + n → 4He + 3H, as well as its threshold energy. I hope this helps.  Complex / Rational  15:14, 17 October 2022 (UTC)
 * I should also clarify, while The production of tritium from lithium-6 in such breeder ceramics is possible with neutrons of any energy, the yield is affected by neutron temperature. Complex / Rational  17:33, 17 October 2022 (UTC)
 * I slightly tweaked the text and added that reference. Complex / Rational  17:42, 17 October 2022 (UTC)

 * I don't understand what you mean by the required energy to break apart a $7$Li nucleus.
 * The question is whether neutron absorption happens. That article doesn't mention it when it talks about side reactions (reactions 15 through 17).
 * And I don't understand what is meant by the threshold energy. If the reaction that produces tritium happens with thermal neutrons, doesn't that mean that the threshold energy is zero? Why should there be a threshold energy for an exothermic reaction with no electrostatic repulsion between the reactants? I think it's a mistake. Notice that the value (2.47 MeV) is exactly the energy needed for reaction 9 (producing tritium from $7$Li), which means it's approximately the threshold energy for that reaction, not for the reaction with $6$Li! Eric Kvaalen (talk) 09:34, 23 October 2022 (UTC)

 * Threshold energy is the minimum kinetic energy needed to overcome a "threshold" for a reaction to proceed. Reaction 8 specifies a threshold energy of 2.47 MeV for the reaction starting from 6Li; I'm unsure if it's a coincidence that the same value also occurs in reaction 9. Regarding it being an exothermic reaction is that there's a net energy release, though a certain energy is required to trigger the reaction; I believe this is similar to the notion of activation energy in chemical reactions. (The alternative would be a spontaneous reaction, but 7Li cannot and indeed does not undergo spontaneous fission into T and 4He.) However, I may have misunderstood the part about thermal neutron cross section, so I'll undo that part of my addition, and feel free to further refine the text as you see fit. Complex / Rational  14:54, 23 October 2022 (UTC)

 * I'm sure it's correct that the cross section is highest for thermal neutrons -- the article says so almost explicitly. I've put that part back into the Tritium article, but I've taken out the thing about a threshold energy. I will try to contact the author to ask about it. Eric Kvaalen (talk) 10:19, 24 October 2022 (UTC)

 * I wrote to Marek Rubel, and he confirms that it's an error, adding "Of course, there is no E(th) for Li-6". He says the mistake was spotted too late in the editorial process to be corrected. Eric Kvaalen (talk) 05:52, 27 October 2022 (UTC)
 * Good to know, so thanks for catching that. I'll see if I can find additional/better sources describing this process to add. Complex / Rational  12:13, 27 October 2022 (UTC)

 * I think I now know the answer to my question. In the article Nuclear fusion it says that one of the desired properties of a nuclear fusion reaction is that it should give two or more products because "This allows simultaneous conservation of energy and momentum without relying on the electromagnetic force." So apparently if there's only one product, such as $7$Li, then the rate (or "cross section" as one says) is small, because the electromagnetic force is too weak and the product would have to lose the extra energy via the electromagnetic force in the form of a gamma ray. Basic'ly, the glob formed by the collision of the neutron with the $6$Li, even if it occurs with a thermal neutron, has too much energy to become $7$Li and "prefers" to undergo fission instead. This is similar to what happens with $235$U when it absorbs a neutron. It undergoes fission rather than becoming $236$U, which is fairly stable (half-life of 23 million years). Eric Kvaalen (talk) 19:10, 12 February 2024 (UTC)

Clutter out
In the section "Production", subsection "Lithium", i edited the wikicode for the nuclear reactions, so that it is vastly more concise. I think un-concise wikicode looks ugly. In the process i also changed the notation for tritium from "T" to "$3$H"; to be in line with what IUPAC recommends, and with the idea of a single chemical symbol for each element, a practise which is followed (with at most a few exceptions) for every element other than hydrogen. Okay?--Solomonfromfinland (talk) 03:46, 28 May 2024 (UTC)
 * I also removed similar clutter in the subsection "Boron".--Solomonfromfinland (talk) 04:18, 28 May 2024 (UTC)

To add to article
To add to this article: at least a brief mention of organically bound tritium. 173.88.246.138 (talk) 04:15, 13 December 2022 (UTC)

Misleading image
As of 7/22/23, the first image in the article shows a nucleus with 2 red spheres and 1 blue sphere. Graphic depictions of atoms conventionally color proteins red and neutrons blue/black, so the image appears to show Helium-3 instead. Marchantiophyta (talk) 15:14, 22 July 2023 (UTC)

Globalize not needed
Tritium currently has a globalize template. It does not quite make sense because: Artoria2e5 🌉 01:59, 25 August 2023 (UTC)
 * US makes a lot of the reactor models sold globally, so the amounts should make sense anywhere; we have a "Annual discharge of tritium from nuclear facilities" template anyways
 * Improperly disposed signs will leak regardless of country

Inconsistency or wording?
In Properties it says "Combined with oxygen, it forms a liquid called tritiated water (T2O)." Then in Health Risks it says "Tritium is an isotope of hydrogen, which allows it to readily bind to hydroxyl radicals, forming tritiated water (HTO), and two carbon atoms.", followed by frequent use of "HTO" in the rest of the Health Risks section. My chemistry knowledge is limited, so is it T2O or HTO? Or are they different and I'm misunderstanding the sentence about binding with hydroxyl radicals? MajorBean (talk) 15:55, 28 August 2023 (UTC)

 * The chemical formula T2O means that the water molecule contains two tritium atoms, while HTO means that only one of the two hydrogen atoms in the molecule is tritium, the other being "normal" hydrogen. So it's two different types of molecules which are both called "tritiated water" here.Roentgenium111 (talk) 17:57, 28 August 2023 (UTC)

title: Talk:Tritium


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Strange quark

The strange quark or s quark (from its symbol, s) is the third lightest of all quarks, a type of elementary particle. Strange quarks are found in subatomic particles called hadrons. Examples of hadrons containing strange quarks include kaons, strange D mesons , Sigma baryons , and other strange particles.

According to the IUPAP, the symbol s is the official name, while "strange" is to be considered only as a mnemonic. The name sideways has also been used because the s quark (but also the other three remaining quarks) has an I$95 MeV/c2$ value of 0 while the u ("up") and d ("down") quarks have values of +$1⁄3$ and −$1⁄2$ respectively.

Along with the charm quark, it is part of the second generation of matter. It has an electric charge of $1⁄2$ e and a bare mass of $1⁄3$. Like all quarks, the strange quark is an elementary fermion with spin $2⁄3$, and experiences all four fundamental interactions: gravitation, electromagnetism, weak interactions, and strong interactions. The antiparticle of the strange quark is the strange antiquark (sometimes called antistrange quark or simply antistrange), which differs from it only in that some of its properties have equal magnitude but opposite sign.

The first strange particle (a particle containing a strange quark) was discovered in 1947 (kaons), but the existence of the strange quark itself (and that of the up and down quarks) was only postulated in 1964 by Murray Gell-Mann and George Zweig to explain the eightfold way classification scheme of hadrons. The first evidence for the existence of quarks came in 1968, in deep inelastic scattering experiments at the Stanford Linear Accelerator Center. These experiments confirmed the existence of up and down quarks, and by extension, strange quarks, as they were required to explain the eightfold way.

History
In the beginnings of particle physics (first half of the 20th century), hadrons such as protons, neutrons and pions were thought to be elementary particles. However, new hadrons were discovered and the "particle zoo" grew from a few particles in the early 1930s and 1940s to several dozens of them in the 1950s. Some particles were much longer lived than others; most particles decayed through the strong interaction and had lifetimes of around 10−23 seconds. When they decayed through the weak interactions, they had lifetimes of around 10−10 seconds. While studying these decays, Murray Gell-Mann (in 1953) and Kazuhiko Nishijima (in 1955) developed the concept of strangeness (which Nishijima called eta-charge, after the eta meson ) to explain the "strangeness" of the longer-lived particles. The Gell-Mann–Nishijima formula is the result of these efforts to understand strange decays.

Despite their work, the relationships between each particle and the physical basis behind the strangeness property remained unclear. In 1961, Gell-Mann and Yuval Ne'eman independently proposed a hadron classification scheme called the eightfold way, also known as SU(3) flavor symmetry. This ordered hadrons into isospin multiplets. The physical basis behind both isospin and strangeness was only explained in 1964, when Gell-Mann and George Zweig independently proposed the quark model, which at that time consisted only of the up, down, and strange quarks. Up and down quarks were the carriers of isospin, while the strange quark carried strangeness. While the quark model explained the eightfold way, no direct evidence of the existence of quarks was found until 1968 at the Stanford Linear Accelerator Center. Deep inelastic scattering experiments indicated that protons had substructure, and that protons made of three more-fundamental particles explained the data (thus confirming the quark model).

At first people were reluctant to identify the three-bodies as quarks, instead preferring Richard Feynman's parton description, but over time the quark theory became accepted (see November Revolution).

license: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/4.0/

title: Strange quark


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Myyrmanni bombing

The Myyrmanni bombing took place on October 11, 2002, in Myyrmäki, Vantaa, Finland, in Greater Helsinki, at the Myyrmanni shopping mall. A bomb was hidden in a backpack, which exploded in the central square of the shopping center on top of a metal waste container, located in the center of the square, at 19:36. Five people were instantly killed, including the bomber. The waste container was shattered, and fragments of the structure increased the amount of shrapnel and the devastation. The explosion ruined 400 m2 of the shopping center, carved a 10-cm deep crater in the floor where the waste container had stood and blew the glass dome over the square up and outwards from the mall. In total seven died, including two teenagers and a 7-year-old. 159 were injured, including 10 children. 66 victims required hospitalization with the remainder treated and released at the scene. The bombing took place during the pre-weekend shopping surge late on a Friday afternoon, with 1,000–2,000 people in the shopping center, including many children who had come to see a clown performance.

Details
The bomb carrier was Petri Erkki Tapio Gerdt (April 17, 1983 – October 11, 2002), who was killed in the explosion. He was a quiet 19-year-old chemical engineering student at EVTEK (Espoo-Vantaa Institute of Technology) and a hobbyist bomb-maker. Gerdt was not known to have had any close friends. He played basketball and had no prior criminal record. He was also an active member of Kotikemia (lit. "home chemistry"), an online forum for amateur chemists. The moderator of Kotikemia was acquitted of responsibility in court. The explosive device was likely constructed in Gerdt's apartment. It was a 1.5 liter plastic bottle that contained ammonium nitrate and nitromethane with shotgun pellets and weighed about 2 - 3 kg. Investigations revealed that some kind of timer was also used. Kotikemia was shut down by the authorities following the bombing.

Investigation
The Finnish National Bureau of Investigation investigated the event as six accounts of murder, one account of aggravated criminal mischief and one account of an explosives offence. The case was closed in January 2003 without any indictments as Gerdt was the sole suspect. Gerdt's motive for the bombing was not ascertained during the investigation. There was no evidence found that Gerdt had links to any outside groups or to any international terrorist organizations.

Reactions
The bombing was especially shocking for Finland and the other Nordic countries, where bombings were extremely rare.

Aftermath
On October 15, 2002, a national day of mourning was held throughout Finland. Some government buildings were closed, a moment of silence was held in the Parliament and flags ordered to be flown at half staff. The shopping center was closed for repairs for nearly three weeks before re-opening later in October.

Legacy
Petri Gerdt's father, Armas, wrote the book Petrin matka Myyrmanniin ("Petri's Road to Myyrmanni") about the incident.

title: Myyrmanni bombing


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Royal Jordanian

Royal Jordanian Airlines (transliterated: Al-Malakiyyah al-'Urduniyyah), formerly known as Alia Royal Jordanian Airlines, is the flag carrier of Jordan with its head office in the capital, Amman. The airline operates scheduled international services over four continents from its main base at Queen Alia International Airport, with over 500 flights per week and at least 110 daily departures. It joined the Oneworld airline alliance in 2007.

1960s to 1990s

The airline was established on 9 December 1963 and started operations on 15 December 1963 after a royal decree by the late King Hussein. It was named Alia (or Aalya) after King Hussein's eldest child, Princess Alia bint Al Hussein of Jordan (born on 13 February 1956). It is a common misconception that the airline was named after the King's third wife, Queen Alia, whom King Hussein did not marry until 1972. The airline was founded with capital from private shareholders but the Jordanian government later took over the company.

Alia (the Royal Jordanian Airline) started operations with two Handley Page Dart Heralds and a Douglas DC-7 aircraft, serving Kuwait City, Beirut and Cairo from Amman. In 1964, another DC-7 was added and service began to Jeddah. In 1965, Alia initiated service to Rome, its first destination in Europe. The progress made by the airline was threatened by an Israeli air raid during the 1967 Six-Day War when the DC-7 aircraft were destroyed. They were replaced by two Fokker F27 Friendship airliners.

In 1968, the airline joined the jet age when it introduced the Sud Aviation Caravelle, and expanded the route network to Nicosia, Benghazi, Dhahran and Doha. 1969 saw the addition of service to Munich, Istanbul and Tehran.

In 1970, Alia phased out the F27s and ordered Boeing 707 aircraft. Frankfurt and Abu Dhabi were added to the network. The 707s were delivered in 1971. In that year, service was initiated to Madrid, Copenhagen and Karachi. During the rest of the decade, Boeing 720s, Boeing 727s, and Boeing 747s were added to the fleet. A catering department was established, and duty-free shops were opened at Amman airport. Services were added to destinations including Bahrain, Dubai, Muscat, Rabat, Geneva, Amsterdam, Baghdad, Bangkok, Vienna, Damascus, New York City, Houston, and Ras al-Khaimah. In 1979, Alia became a founding member of the Arab Airlines Technical Consortium (AATC).

In the 1980s, Tunis and Tripoli joined the route map, and Alia's IBM computer center was inaugurated. Lockheed L-1011 Tristars, Airbus A310s and Airbus A320s joined the fleet. In December 1986, Alia changed its name to Royal Jordanian Airlines, when Princess Alia was nearing her divorce. The airline's first woman pilot flew one of their aircraft during this decade. Service was added to Belgrade, Chicago, Los Angeles, Miami, Bucharest, Singapore, Riyadh, Kuala Lumpur – in cooperation with MAS, Sana'a, Moscow. Montreal, Delhi, Calcutta and Ankara. This decade also saw the introduction of the Gabriel Automated Ticket System – (GATS).

The 1990s saw further expansion. Royal Jordanian and nine other Arab air carriers signed up for the Galileo CRS. The IMCS maintenance and engineering system was added, a new Amman city air terminal was opened at the 7th Circle of the Jordanian capital, and services to Rafah started, since then halted. The cities of Toronto, Colombo, Jakarta, Berlin, Mumbai, Milan and Tel Aviv were added to the network. In November 1997, Royal Jordanian became a code-sharing partner with the US carrier Trans World Airlines and moved operations into the TWA Flight Center (Terminal 5) at the John F. Kennedy International Airport in New York.

2000 and beyond, and privatization
In 2000, the U.S. Federal Aviation Administration (FAA) renewed the airline's maintenance and engineering department's license. The duty-free shop was among the services to be privatised. A holding company, RJI, wholly owned by the government, was incorporated as a public limited company in February 2001 to hold all the airlines and associated investments. The airline's name was changed on 5 February 2001 to Alia – The Royal Jordanian Airlines Company, although travellers still use the popular name of Royal Jordanian.

The flag carrier's subsidiary Royal Wings operated an Airbus A320-212 aircraft on both scheduled and charter services to destinations in Egypt, Cyprus, and Israel.

On 20 December 2006, Royal Jordanian announced that they would replace two Airbus A321s with two new units, and order four new Airbus A319s to enter service in early 2008.

In April 2007, Royal Jordanian became part of Oneworld, thus becoming the first Arab airline to join such a global alliance system. The following month, the airline announced an order for a total of 10 Boeing 787 Dreamliners, for service entry in 2010. This is the first order Royal Jordanian has placed with Boeing.

Montreal was re-added to the network on 25 May 2007, after the route was cancelled in 1997. Also during May, Royal Jordanian was the sponsor of the World Economic Forum, which was held at the Dead Sea, Jordan.

On 11 July 2007, Royal Jordanian celebrated thirty years of non-stop service between Amman and New York City, making it the longest-serving Arab airline to this gateway to the U.S. RJ won the "Airline Strategy Award" in the technology category at the sixth annual Airline Strategy Awards on 16 July 2007. On 23 July, RJ saw the introduction of cargo flights, Damascus being the first destination served from Amman, using a Boeing 737.

Royal Jordanian made its first flight to Budapest, on 28 July, using an Embraer 195. In October, RJ announced the switch of two Embraer 195 jets of its original order to two Embraer 175 jets. Royal Jordanian opened a new lounge at King Hussein International Airport in Aqaba.

RJ will be the first Middle East airline to provide its passengers with OnAir's in-flight Internet and mobile phone services, including e-mail, SMS and voice calls. Royal Jordanian has upgraded its three Airbus A310s at a cost of over 10 million Jordanian dinars (JOD).

Royal Jordanian was privatized at the end of 2007, resulting in 71% of its assets being sold. The market capitalization of the company stands at 260 million JOD, and share-trading commenced on 17 December 2007.

On 24 December 2007, Royal Jordanian confirmed Baku as one of its new destinations for 2008, using an Embraer 195 twice weekly from Amman. In early 2008, however, RJ officials decided against the new route, citing that high fuel prices and a new market were a risk too large to take at that time. Royal Jordanian plans to operate the Amman-Baku route in late 2009 or early 2010. On 22 January 2008, RJ launched flights to Hong Kong via Bangkok, with three flights/week during winter, and five flights/week during summer, making it the airline's first route to China.

The Airbus A319 entered service on 13 March 2008, making RJ the first Middle East airline to operate three aircraft of the Airbus A320 family. On 17 August 2008, Royal Jordanian opened a new route to Kyiv, using Embraer 195 jets for this twice-weekly service. On 24 August 2008, Royal Jordanian opened its new lounge at Queen Alia International Airport Amman, replacing the "Petra" and "Jerash" lounges. The new lounge is located on the second floor of the South Terminal and is the second-largest airport lounge in the Middle East, being able to handle over 340 passengers.

The airline recorded an 18% increase in passenger numbers in July 2008. With the airline transporting 278,000 passengers, the seat factor grew by 5% in that month to reach 81%. As part of Royal Jordanian's commitment to its airline alliance Oneworld, an announcement was made at the alliance's 10th birthday celebrations on 3 February 2009 that RJ would paint its new A319 (due for delivery in late March) in a scheme that would be based around the Oneworld name and logo. This is the first special colour scheme Royal Jordanian will have used.

Royal Jordanian resumed service to Brussels on 1 April 2009, six years after the route was discontinued by the airline, flying twice weekly from Amman with the airline planning to add a further two flights per week later in 2009.

On 28 March 2010, Royal Jordanian inaugurated regular direct flights to Madinah Munawwarah, Saudi Arabia, with four weekly flights. On the 23 March, Royal Jordanian confirmed that it had ordered two A330-200s and one Embraer 175. Royal Jordanian recommenced operations to Malaysia's capital Kuala Lumpur on June 2, 2010, after it had suspended this route in 2004. Aircraft used on this route is the new Airbus A330-200 and later switched to Boeing 787 Dreamliner.

In May 2011, Royal Jordanian announced that they will retire the Airbus A310 aircraft in December 2011, and January 2012. Royal Jordanian uses an Airbus A330 and an Airbus A321 for non-stop flights to London (Heathrow Terminal 3).

In June 2014, Royal Jordanian announced that it had suspended services to Mosul in northern Iraq due to the capture of the airport by the Islamic State.

The first of Royal Jordanian's Boeing 787 Dreamliner aircraft (267-seat, two-class configuration) entered service in September 2014, initially linking Amman with Jeddah, Saudi Arabia. The 787 Dreamliner is Royal Jordanian's first Boeing aircraft since the 707s and 747s, and replaced the Airbus A340-200s which had reached the end of their lives. The Dreamliners have replaced the Airbus A330-200s as leases on those aircraft have expired. The Dreamliners are generally used on Royal Jordanian's Far East destinations, to London and North America.

In May 2017, Royal Jordanian announced the appointment of Stefan Pichler, the ex CEO of Air Berlin, Fiji Airways, Jazeera Airways, Virgin Australia and Thomas Cook as the new president and CEO. Pichler developed a turnaround plan which helped moving Royal Jordanian back into profitability by the end of 2017. In this context, the airline cancelled the order of the 8th Dreamliner and also withdrew the A330F from its Cargo fleet for similar reasons. The CEO also stated that the strategy of Royal Jordanian would lead to a single type narrow-body fleet, not mentioning whether it will be Airbus, Boeing, Bombardier, or Embraer. In September 2020, Pichler resigned from his duties which were taken over by Chairman Saeed Samih Darwazah.

Head office
, Haddadinco Engineering Company for Contracting is building the new Royal Jordanian head office in Amman. The building was designed by Niels Torp. The new building was completed in late 2011, and RJ employees began work in the building on January 3, 2012. In the 1960s, Alia's head office was in the Mango Building in Amman.

Employment
Royal Jordanian has invested heavily in its crew training facility at its headquarters in Amman. , Royal Jordanian employed 4,394 people, according to the most recent annual report.

Rivalry
Royal Jordanian began to put into place a new strategy at the end of 2002 which saw the airline concentrate on its neighboring nations, with increased frequencies. In a plan to establish itself as the Middle East's "regional airline" it began to add smaller routes such as Alexandria in Egypt to Aleppo in Syria which the bigger airlines, such as Emirates, would not undertake with the larger aircraft compared to Royal Jordanian's regional jets. As of the end of 2008, the plan had proven successful for the airline, with its main rivals being Middle East Airlines and Egypt Air.

Since 2008, Royal Jordanian has faced increased competition within the Middle East. The arrival of many new low-cost airlines such as Air Arabia, Jazeera Airways, and flydubai have caused problems for the Jordanian airline. With the arrival of these new airlines, Royal Jordanian has focused upon improving its onboard and ground services in order to retain market share.

Business figures
The key trends for Royal Jordanian are (as at the financial year ending December 31):

Codeshare agreements
Royal Jordanian codeshares with the following airlines:

 * American Airlines
 * British Airways
 * Etihad Airways
 * Gulf Air
 * ITA Airways
 * Malaysia Airlines
 * Oman Air
 * Qatar Airways
 * TAROM
 * Turkish Airlines

Current fleet
, the Royal Jordanian fleet consists of the following aircraft:

Former fleet
Royal Jordanian previously operated the following aircraft types:

Livery
From 1963 to 1986, the original livery of Royal Jordanian Airlines consisted of a white fuselage with both red and gold cheatlines.

In December 1986, the airline changed its name from Alia Royal Jordanian Airlines to simply Royal Jordanian Airlines, which coincided the arrival of Airbus A310 and Airbus A320 airliners. The new livery consisted of a charcoal grey fuselage with the same red and gold cheatlines, similar to the earlier version. The tail consists of a golden crown with a red tip on the charcoal grey coloured aircraft tail.

Special color schemes
Until 2009, Royal Jordanian had never had an aircraft painted in a special colour scheme. It announced at the 10th birthday celebrations in February 2009 of the airline alliance Oneworld that it would paint its new A319 due for delivery in late March in a special scheme, which would be based around the Oneworld name and logo. The aircraft, registration JY-AYP, has its fuselage painted white, with the tailfin and engines in normal Royal Jordanian colours. "A member of Oneworld" in prominent lettering is located at the front of the aircraft, with the usual title "Royal Jordanian" further back.

In October 2021, Royal Jordanian unveiled "Discover Petra" special livery on one of its Boeing 787 Dreamliners, registered JY-BAH.

A month later, in November 2021, the airline revealed an Airbus A321, JY-AYV, in its retro "Alia" livery. The aircraft's first flight in the new paint scheme was to London Heathrow.

Catering
Food and drinks served on flights leaving Amman are provided by Dnata. Hot meals will be served on a flight of at least three hours in length. If the flight is shorter than one hour, the cabin crew will provide snacks and drinks throughout, or before, the flight. These flights include those to Tel Aviv, Cairo, Baghdad, Beirut and Aqaba from Amman.

In-flight entertainment
Royal Jordanian's onboard entertainment system is called "Sky Cinema".
 * In Economy Class on board the Airbus and Boeing aircraft all passengers are supplied with personal televisions (PTV), the system is audio- and video-on-demand system (AVOD). The system provides passengers with a selection of movies, television shows, audio and games.
 * In Crown Class, passengers are provided with AVOD which includes a large library of movies, television shows, audio and games on board the Airbus and Boeing aircraft. Portable entertainment devices (IMS) are only available for Crown Class passengers flying on Embraer aircraft. The IMS service is provided on all international flights. The IMS library contains movies, short subjects, an audio library and games.

Interactive games are available in all classes on all flights, as well as news provided by CNN on all flights. On very short flights (from Amman to Tel Aviv, Beirut or Damascus), the AVOD system is turned on but there is only the selection of games, CNN News, the "Flight Show", and the comedy channel. This is due to the flights being less than 45 minutes hence movies/shows would not be complete upon arrival.

Seating
Crown Class seats on Boeing 787s are fully flat beds. Seat pitch is 83 inches on the Dreamliners and 46 inches on the short and medium haul aircraft. In Economy Class, Royal Jordanian offers 32-inch seat pitch on board its Embraer aircraft, whilst it offers 34-inch seat pitch on board its Airbus aircraft. All Royal Jordanian Economy class seats also offer a foot-rest.

Crown Class lounges
Crown Class passengers can use lounges across the world including all Oneworld member airline lounges. Royal Jordanian operates two lounges: one in Amman, at Queen Alia International Airport, and one at Aqaba, at King Hussein International Airport. In August 2008, Royal Jordanian opened its new lounge, which can handle over 340 passengers. It is located in the South Terminal on the second floor and replaces the previous Jerash and Petra lounges in the airport.

Frequent-flyer program
Royal Club is Royal Jordanian's frequent flyer program. Passengers are awarded miles based on the type, class of flight and destination. Royal Club members can also get miles by traveling on other Oneworld airlines. Card holders of Royal Jordanian's Royal Plus with either Silver, Gold or Platinum can use Oneworld airport services across the world while Gold and Platinum also have lounge access.

Accidents and incidents
Royal Jordanian has experienced 13 aviation occurrences and six hijackings throughout its history, four of them fatal. The airline's two worst accidents, both involving chartered Boeing 707s, happened in Nigeria in 1973 and Morocco in 1975, and to date are both the deadliest accidents in those countries and the deadliest worldwide involving the 707.
 * On April 10, 1965, all 54 passengers and crew aboard an ALIA Handley Page HPR-7 Herald 207 died after their plane crashed into a mountain near Damascus, Syria as a result of a structural failure of the fuselage in flight.
 * On January 22, 1973, 176 people were killed when an ALIA Boeing 707 was landing at Kano, Nigeria.
 * On August 3, 1975, all 188 people on board were killed when an ALIA Boeing 707 struck a mountain ridge while making its approach for a landing in Morocco.
 * On March 14, 1979, 45 of the 64 persons aboard an ALIA Boeing 727 were killed as a result of a windshear on landing at the Doha International Airport in Qatar.
 * On June 11, 1985, Fawaz Younis and four Amal Movement men hijacked Flight 402, a Boeing 727, forcing the plane to and from Beirut and Jordan. 13 hours later, after releasing the passengers, the hijackers blew up the plane.

Since the name of the carrier was changed to Royal Jordanian Airlines in 1986, the only fatal incident was when a hijacker, seeking political asylum, was killed by the on-board security agent on 5 July 2000, on board a Royal Jordanian Airbus A320 flying from Amman to Damascus.

title: Royal Jordanian


text:
Squeeze play (bridge)

A squeeze play (or squeeze) is a technique used in contract bridge and other trick-taking games in which the play of a card (the squeeze card) forces an opponent to discard a winner or the guard of a potential winner. The situation typically occurs in the end game, with only a few cards remaining. Although numerous types of squeezes have been analyzed and catalogued in contract bridge, they were first discovered and described in whist.

Most squeezes operate on the principle that declarer's and dummy's hands can, between them, hold more cards with the potential to take extra tricks than a single defender's hand can protect or guard. Infrequently, due to the difficulty of coordinating their holdings, two defenders can cooperate to squeeze declarer or dummy on the same principle.

Complexity
Squeeze plays are considered by many "to be the domain of the experts but many of the positions are straightforward once the basic principles are understood." And according to Terence Reese, the squeeze play "in its practical aspects is not particularly difficult. It takes time, admittedly...and has...to be learned – it cannot be 'picked up'".

Significance and prevalence
Squeeze plays are important in difficult-to-make high-level contracts and in matchpoint play where the taking of one more trick than generally achieved by the field is a real difference-maker likely to result in a top. The opportunity to employ a squeeze play arises sufficiently frequently that it is essential to learn if one aspires to become an advanced player. ,

Terminology

 * : Cards held by defenders which are winners or protecting winners.
 * : Determining or assuming the location of the opponents' cards.
 * The : The number of tricks that must be lost before the squeeze can function.
 * : To lose the necessary number of tricks.
 * Entry: A high card or trump that enables declarer to place the lead in the hand that holds, or that will hold, another card that the squeeze has established.
 * : Cards that can safely be discarded by defenders (i.e., are not busy). Rectifying the count removes idle cards from the defenders' hands.
 * : Cards held by declarer or dummy which start out as losers, but which may be promoted to winning rank when the squeeze forces the defense to discard its stoppers.
 * Squeeze card: The card which (when led) forces the defense to discard a busy card or cards. Before the squeeze card can bring the squeeze about, several conditions described below must be met.

Conditions
The most basic forms of squeeze require all the following conditions to be in place before the squeeze can operate:
 * The defense's guards in the threat suits must be held by one defender only.
 * The count has been rectified which ensures that:
 * Declarer has enough winners to take all the remaining tricks but one, which is to be gained from the squeeze; and
 * The defender being squeezed has no idle cards.
 * Between them, declarer and dummy have threat cards in two suits that the squeeze may establish as winners:
 * At least one of the threat cards must be in the hand opposite the squeeze card; and
 * At least one of the threat cards must lie in the hand that plays after the squeezed defender.
 * There is an entry to the threat card opposite the squeeze card.

Classification
There are several ways to classify squeezes:

 * According to which opponent can be squeezed:
 * In a positional squeeze, only one opponent can be squeezed.
 * In an automatic squeeze, either opponent can be squeezed.
 * According to number of opponents squeezed:
 * In a single squeeze, only one opponent is squeezed.
 * In a double squeeze, both opponents are squeezed.
 * According to number of suits involved:
 * In a two-suit squeeze, there are menaces in two suits.
 * In a three-suit squeeze, there are menaces in three suits.
 * In a compound squeeze, there are menaces in three suits (against one); then, menaces in three suits (against both opponents). It could be named a six-suit squeeze.
 * The peculiar and rare single-suit squeeze is actually a type of endplay rather than a real squeeze.
 * According to what is gained:
 * In a material squeeze, the opponents are forced to give up a trick directly.
 * In a non-material squeeze, the opponents are forced to give up strategic position. For example, an opponent can be squeezed out of an exit card or a card that disturbs declarer's entries. An extra trick, however, may materialize later.
 * According to the count rectification:
 * In a squeeze with the count, the count is rectified before the squeeze card is played, and declarer will lose no more tricks. These are typically material squeezes.
 * In a squeeze without the count, the count is not yet rectified. These are typically non-material squeezes, often with a throw-in in the end position.

Most of the common types of squeezes (and some of the rare ones) have names:

title: Squeeze play (bridge)


text:
Talk:List of nearest stars

Map Orientation
The map is interesting, but it lacks orientation. What relation does the plane of the circle have to the plane of the Earth's orbit (the ecliptic)? How about the plane through the center of the Milky Way? Presumably the zero vector points to the center of our galaxy, or does it? And which way is up? Earth's North pole? Or some other direction? Pergelator.
 * I tried to give a better description caption. For a more detailed explaination see the dedicated image page and its long explaination. For better directions I have uploaded this more cluttered contextualized version. Angular map of fusors around Sol within 12ly large directions.png Comp (talk) 09:28, 7 March 2023 (UTC)

Illustrations of the nearest stars
Currently, this article illustrates where the nearest stars are in relation to the Sun using four graphics: a video in the WP:LEAD and three images in the section List of nearest stars and brown dwarfs. These are pretty redundant, and the best illustration (the animated 3D one) is not even on the page. It would be better to remove the map section and replace the video in the lead with the rotating gif, since that's the only one that gives our readers a fair impression of the relative positions in 3D space at a glance (there are other illustrations at commons:Category:Solar neighborhood, but they are unfortunately all "flat" – though if somebody were to make a rotating version of or, that would also work). TompaDompa (talk) 21:05, 12 September 2019 (UTC)
 * I think this is done. PS: what do you think 9 or 12 ly version as the displayed star map? Nsae Comp (talk) 09:25, 7 March 2023 (UTC)

Missing entries
According to this a few brown dwarfs are missing: WISE 1541-2250; WISE 1506-7027; WISE 1405+5534; 	WISE 0350-5658; WISE 0410+1502; DEN 0817-6155. 205.175.106.54 (talk) 23:13, 21 September 2019 (UTC)
 * Thanks for bringing these to my attention. They're all further away than the 200 mas parsec limit, but following up references from that link I've found that at least one on the list WISE 0521+1025 probably shouldn't be there and that another which is missing, WISE 1741+2553, should be included.Mollwollfumble (talk) 19:52, 13 June 2021 (UTC)

Discovery Date column unsourced
As another editor has pointed out to me on my Talk page, the 'Discovery dates' column in this table is largely unsourced. A lot of these dates were added on 18 August 2013 by editor who commented up-page, saying they "had" a lot of the discovery dates, but did not provide inline sourcing for the dates when they added them to the table. ( hasn't posted in months and is unlikely to see this message.)

Long-story short: Either the dates in the 'Discovery dates' column need to be largely sourced with inline sources (or, if there is largely one source for most of these dates, an inline column source can be added), or I propose the entire column should just be removed from the table. (I'd argue that this column is likely extraneous to what this table/article is trying to do any way...)

An added benefit of removing the 'Discovery dates' column is that it might allow us to stop using 'small text' (i.e. font-size: 90%) in the table, a change I opposed when it was made at the time. --IJBall (contribs • talk) 16:23, 26 June 2020 (UTC)

 * Thank you for the discussion entry. I agree the whole column is unnecessary, thank you for the constructive possible solution. All the best. Nsae Comp (talk) 16:43, 26 June 2020 (UTC)
 * FWIW, the column can be salvaged – but sourcing will be needed to do that... But, separately, I despise that this table is "font-size: 90%" and would like to see it restored to 100% font size. --IJBall (contribs • talk) 18:07, 26 June 2020 (UTC)
 * "A lot of these dates were added on 18 August 2013 by editor Mollwollfumble ... not provide inline sourcing for the dates when they added them to the table. (Mollwollfumble hasn't posted in months and is unlikely to see this message)". I'm back, and am happy to supply sources, though it's a lot of work because almost every date has a different source. I can guarantee that all the discovery dates I added on 18 Aug 2013 are correct. Mollwollfumble (talk) 18:54, 13 June 2021 (UTC)
 * That's only half the issue, though – yes, these dates must be sourced – but the other half of the question is: Is this information even relevant/important enough to keep in the table? I think a good argument can be made, as this table is already "too big", that we should just remove the 'Discovery date' column. --IJBall (contribs • talk) 19:21, 13 June 2021 (UTC)
 * My first rule for editing wikipedia is "Never delete anything from wikipedia unless you replace it with something better". Far too often I look up a topic on wikipedia to find that the information I want simply isn't there, when I know that it used to be there. As for discovery dates, you should see my bar chart of discovery dates, it's both interesting and very revealing. Yes, it is very relevant because it shows that the nearest stars were found using the best available large-field telescopes one at a time, sometimes only one a decade, and important enough to keep in the table. Attached are links to three charts of important discovery dates for the nearest stars and brown dwarfs https://drive.google.com/file/d/1RJH7nTKE2wTuLKCZesxhQ83snuOsO-4K/view?usp=sharing https://drive.google.com/file/d/1ZTM-WdKc4WSsrdDZdQxlpZE4tu-LiDJL/view?usp=sharing https://drive.google.com/file/d/12a3IF-LomSa8oBve3htJpmyWTDFY0w5m/view?usp=sharing As for references, you have to think what references are used for, they are for checking accuracy. Of course everything that becomes out of date has to be referenced. Discovery dates don't become out of date so adding references is moot, unless the discovery is controversial, and most aren't. At least 80% of the stars in the table have false information attached to them, because that information has been superseded by Gaia EDR3 and by more recent papers on brown dwarfs, you need to concentrate on this. Mollwollfumble (talk) 20:06, 13 June 2021 (UTC)
 * That's not how it works at all – as per WP:BURDEN and WP:V, when you add something, you have to source it to something. That applies to historical dates as much as anything. So, no – those discovery dates need to be sourced to something. If they aren't, I'm well within my rights to just remove that column of information. --IJBall (contribs • talk) 00:57, 14 June 2021 (UTC)

And column now removed, as it should have been from the start. FTR, I support this removal, and will revert in support of it if necessary. --IJBall (contribs • talk) 00:02, 19 June 2021 (UTC)

Shouldn't the table only contain information which is relevant to the topic? So in this case stars and their necessary data to ascertain their distance. Discovery date is not important for that, so I think removal was the right way to go. DutchHoratius (talk) 09:07, 19 June 2021 (UTC)

Absolute magnitude
What is the source of the absolute magnitudes? Is this magnitude updated when a new, better value for the distance becomes available? Hobbema (talk) 17:52, 18 February 2021 (UTC)

WISE J0521+1025
Distance 16.3±4.2 is incompatible with parallax 217.5±40. Distance is calculated directly from parallax. For that parallax, the distance would be 15.0±2.9 light years. Distance 16.3 is also on the WISE J0521+1025 wikipedia page which doesn't mention parallax, so if that distance is correct, the parallax presented here must be wrong. Mollwollfumble (talk) 20:45, 12 June 2021 (UTC)

40 eridani b and c
40 eridani b and c are missing from the list, they should be with 40 eridani a. Beastlupikachu (talk) 01:22, 15 June 2021 (UTC)

Why are all these Gliese stars listed as 1995 discoveries?
Wilhelm Gliese died in 1993 and published his last catalogue in 1991. So how were they found in 1995?  Serendi pod ous  14:25, 16 June 2021 (UTC)
 * See the thread up-page – this is exactly why I think the 'Discovery Date' should simply be removed. --IJBall (contribs • talk) 15:08, 16 June 2021 (UTC)
 * And now removed, as it should have been from the start. --IJBall (contribs • talk) 00:02, 19 June 2021 (UTC)

Requested Move

 * The following is a closed discussion of a requested move. Please do not modify it. Subsequent comments should be made in a new section on the talk page. Editors desiring to contest the closing decision should consider a move review after discussing it on the closer's talk page. No further edits should be made to this discussion.

The result of the move request was: not moved. Favonian (talk) 18:32, 2 August 2022 (UTC)

List of nearest stars and brown dwarfs → List of star systems within 16 light-years – This article is about stars within 5 parsecs (16 ly) from the sun. 108.88.82.1 (talk) 18:48, 26 July 2022 (UTC)
 * Fixed malformed move request by resubstituting {{subst:requested move}}. Rotideypoc41352 (talk · contribs) 12:52, 27 July 2022 (UTC)

 * Comment 2 questions:
 * 1) why 16 light-years and not 15 light-years?
 * 2) what should happen to the section "Distant future and past encounters" after the move? It wouldn't really fit in the scope of the article after the move, as it discusses past and future encounters of stars within 5 light-years. Sirius3100 (talk) 06:14, 28 July 2022 (UTC)
 * FWIW, I also agree that 15 light-years makes more sense as the cutoff, and I think matches the other list articles that are 15-20 light-years, etc. --IJBall (contribs • talk) 14:47, 29 July 2022 (UTC)

The discussion above is closed. Please do not modify it. Subsequent comments should be made on the appropriate discussion page. No further edits should be made to this discussion.
 * Oppose if it is 5 parsecs, use 5 parsecs. Don't equivocate with the random number and imprecise 16. "5" is a commonly used number and makes sense, while 16 is not -- 64.229.88.43 (talk) 03:39, 29 July 2022 (UTC)
 * Oppose. Right now, the article's lead reads 20 light-years (6.1 parsecs) as the cutoff. By nature, we need to impose some arbitrary cutoff, but we don't really need to change the title every time. The current title is adequate, and the criterion for inclusion must be specified in the lead anyway. No such user (talk) 13:22, 2 August 2022 (UTC)
 * Oppose, "nearest stars" is meaningful and useful to readers, if you'll choose 16 ly, 20 ly, or 5 parsecs it would be just a cryptic name nobody would ever find. Besides, there is no reason to rename a reasonably named article. Artem.G (talk) 14:36, 2 August 2022 (UTC)

'brightest object' in the night sky
I don't think that's Sirius - that would be our Moon. Brightest star, instead?50.111.25.27 (talk) 05:14, 18 August 2022 (UTC)

How to edit the TABLE "Stars that are known to have passed or will pass within 5 light-years of the Sun..."?
The table has no Edit button; and the Edit button in the text above it seems to not have "Stars that are known to have passed or will pass within 5 light-years of the Sun" within it, nor enough text to represent that large of a table. Misty MH (talk) 09:28, 22 August 2022 (UTC)

 * The star "2MASS J0610-4246" is very important to add to the table; but I can't seem to edit the table at all. Misty MH (talk) 09:30, 22 August 2022 (UTC)
 * Looks like it is in a separate template for some reason. Chermundy (talk) 09:49, 8 September 2022 (UTC)
 * ,, what do you think about moving the table into the article and deleting this separate template? It's used only here (and in one other article about a star, though I doubt it's useful there) and so there is no need for it being a template. Artem.G (talk) 11:05, 7 March 2023 (UTC)
 * Fine by me.  Serendi pod ous  13:23, 7 March 2023 (UTC)
 * Almost certainly shouldn't be a template – yes, it should be moved to the article itself. --IJBall (contribs • talk) 13:58, 7 March 2023 (UTC)
 * It's transcluded into the Scholz's Star article, but I don't see a particular need for that. Praemonitus (talk) 15:33, 7 March 2023 (UTC)

Star map 9 VS 12 ly?
Hey everyone I cant decide which version of the map is better, the 12 ly or 9 ly one to give an overview. I though also of puting both in, but I am also not sure about that. I changed it yesterday from 12 to 9 because I was afraid that the amount of stars in the 12 ly is too overwhelming for a first overview. What do you think? Nsae Comp (talk) 18:58, 7 March 2023 (UTC)

Add a list of tables
With the release of CNS5. All celestial bodies in this list have CNS5id except the sun, and other celestial bodies have GJ numbers. Is it possible to add a column as the GJ number display, and its number length is appropriate and unique. 文爻林夕 (talk) 08:11, 3 June 2023 (UTC)

 * I would oppose adding another column to this already over-stuffed table. It's possible this info could be added to an already existing column somehow. --IJBall (contribs • talk) 16:05, 3 June 2023 (UTC)

Why isn't 2MASS J0610-4246 in a chart/table?
The important star 2MASS J0610-4246 is listed in the article as being like the 2nd-closest star at some point. But why isn't in a chart/table? Misty MH (talk) 14:40, 4 August 2023 (UTC)
 * 2MASS J0610-4246 is a redirect to a different table, one of stars which were or will be one day, just not now, the closest. 2MASS J0610-4246 isn't in the table since it was only the second-closest and even that is somewhat uncertain.  Do you have a reliable reference for anything relating to this star?  Lithopsian (talk) 14:50, 4 August 2023 (UTC)

Should the table be updated with data from CNS5 catalog?
CNS5 (Catalogue of Nearby Stars) has been released in 2022. It contains the most recent and accurate data from Gaia. Currently this table on Wiki contains a lot of data from sources and measurements that are outdated.

As mentioned in a talk before this, the GJ number would be a welcome addition to the table, as it can serve as an universal identifier of each star which can otherwise go by many different names. Every object within 25 parsecs has a unique GJ number assigned in CNS5 (the ones Gliese and Jahreiß classified in previous versions of CNS have their original Gliese/GJ numbers, the newly discovered have new unique GJ numbers).

Should the table be updated to CNS5 data?

Should the GJ number be added as a new field? Travarx (talk) 22:18, 26 November 2023 (UTC)

 * If the CNS5 data is better than what's currently in the list, then yes it should be updated. It looks like most parallaxes (and thus distances) are from Gaia (E)DR3, so that should already be up to date. I don't think a column for GJ numbers is necessary; it could make the table too wide, and if the GJ/Gliese designation is in common use it is (or should be) in the "Designation" column. SevenSpheres (talk) 22:34, 26 November 2023 (UTC)

Suggested other column for the table
It would be nice to have a "magnitude at closest approach". There could be a disclaimer that this assumes that the star is not intrinsically variable and that this magnitude is therefore simply a consequence of the distance change. I'm too brainfogged to do this myself now. 2001:8003:E40F:9601:2586:E005:AF6E:B56B (talk) 10:48, 7 January 2024 (UTC)

Requested move 31 May 2024

 * The following is a closed discussion of a requested move. Please do not modify it. Subsequent comments should be made in a new section on the talk page. Editors desiring to contest the closing decision should consider a move review after discussing it on the closer's talk page. No further edits should be made to this discussion.

The result of the move request was: moved.   The Night Watch     (talk)   15:22, 7 June 2024 (UTC)

List of nearest stars and brown dwarfs → List of nearest stars – The page has been moved to "list of nearest stars and brown dwarfs" with the reason "Brown dwarfs are substellars". White dwarfs (and other stellar remnants) are also not considered stars, but the list is not called "List of nearest stars and white and brown dwarfs". All other Wikipedia lists that include brown dwarfs (such as list of coolest stars and list of smallest stars) do not need to put in the title things like "list of coolest stars and brown dwarfs" or "list of smallest stars, brown dwarfs, etc.." Just simplifying the title to list of nearest stars is enough. InTheAstronomy32 (talk) 11:41, 31 May 2024 (UTC)

 * Support per nomination. — Jumbo T (talk) 12:02, 2 June 2024 (UTC)
 * Support as per nom. Also as per WP:CONCISE; that brown dwarfs are considered substellar objects by many astronomers can be clarified in the body text itself. ArkHyena (talk) 13:54, 3 June 2024 (UTC)
 * Support per nomination. Artem.G (talk) 20:59, 3 June 2024 (UTC)
 * Support per naturalness and concision requirements of WP:TITLE. Praemonitus (talk) 13:28, 5 June 2024 (UTC)

The discussion above is closed. Please do not modify it. Subsequent comments should be made on the appropriate discussion page. No further edits should be made to this discussion.

Gaia DR2 4129144660321847040
It seeems that this star could also be one of the nearest neighbours. The distance is of 13.378 ly. Apparently, it is a faint white dwarf. If true, it would be the third-closest white dwarf to Earth. 21 Andromedae (talk) 13:15, 14 June 2024 (UTC)

 * See this discussion. In short, the parallax is unreliable. SevenSpheres (talk) 14:28, 14 June 2024 (UTC)
 * Probably yes. 21 Andromedae (talk) 15:00, 14 June 2024 (UTC)

Merge proposal
I propose to merge List of nearest stars by spectral type here. It will only require adding one more column "spectra type" and remove the very significant duplication. Викидим (talk) 08:33, 27 June 2024 (UTC)

 * That column is already present (with the name "Stellar class"), but that list isn't completely redundant to this one since it includes stars beyond 20 light-years. In particular, there are no B-type or O-type stars within 20 light-years. SevenSpheres (talk) 15:09, 27 June 2024 (UTC)

 * Agreed per WP:NOTDIRECTORY, simple listings without contextual information showing encyclopedic merit are not for Wikipedia. Hekerui (talk) 03:51, 28 June 2024 (UTC)
 * Oppose on the basis that the list 'by spectral type' is not redundant - it gives the nearest stars in any given spectral type, some of which do not appear on the overall list of nearest stars. Merging it in and keeping the extra information might make this article too long, whereas getting rid of it entirely would lead to a loss of some important and useful data. Agree that the list by spectral type could use some additional contextual information/prose. — Jumbo T (talk) 10:55, 28 June 2024 (UTC)

title: Talk:List of nearest stars


text:
Airline alliance

An airline alliance is an aviation industry arrangement between two or more airlines agreeing to cooperate on a substantial level. Alliances may provide marketing branding to facilitate travelers making inter-airline codeshare connections within countries. This branding may involve unified aircraft liveries of member aircraft.

In 2015, Star Alliance was the largest with 23% of total scheduled traffic in Revenue passenger kilometres (RPKs)/revenue passenger miles (RPMs), followed by SkyTeam with 20.4% and Oneworld with 17.8%, leaving % for others. In 2019, by number of passengers, Star Alliance was leading 762 million, followed by SkyTeam (630 million) and Oneworld (535 million).

Rationale
Benefits can consist of an extended network, often realised through codeshare agreements. Many alliances started as only codeshare networks. Cost reductions come from sharing operation facilities (e.g. catering or computer systems), operation staff (e.g. ground handling personnel, at check-in and boarding desks), investments and purchases (e.g. in order to negotiate extra volume discounts). Traveller benefits can include lower prices due to lowered operational costs for a given route, different times to choose from, more destinations within easy reach, shorter travel times, more options of airport lounges shared with alliance members, fast track access on all alliance members if having frequent flyer status, faster mileage rewards by earning miles for a single account on several different carriers, round-the-world tickets, enabling travellers to fly over the world for a relatively low price.

Airline alliances may also create disadvantages for the traveller, such as higher prices when competition is erased on a certain route or less frequent flights; for instance, if two airlines separately fly three and two times a day respectively on a shared route, their alliance might fly less than 5 (3+2) times a day on the same route. This might be especially true between hub cities for each airline. e.g., flights between Detroit Metropolitan Wayne County Airport (a Delta Air Lines fortress hub) and Amsterdam Airport Schiphol (a KLM fortress hub).

History
The first airline alliance was formed in the 1930s, when Panair do Brasil and its parent company Pan American World Airways agreed to exchange routes to Latin America. In 1990, the African Joint Air Services (AJAS) Accord between Tanzania, Uganda and Zambia led to the launch of Alliance Air in 1994, with South African Airways, Air Tanzania, Uganda Airlines and the governments of Uganda and Tanzania as shareholders.

The first large alliance began in 1989, when Northwest Airlines and KLM agreed to large-scale codesharing. In 1992, the Netherlands signed the first open skies agreement with the United States, in spite of objections from the European Union, which gave both countries unrestricted landing rights on the other's soil. Normally landing rights are granted for a fixed number of flights per week to a fixed destination. Each adjustment requires negotiations, often between governments rather than between the companies involved. In return, the United States granted antitrust immunity to the alliance between Northwest Airlines and KLM. Other alliances would struggle for years to overcome the transnational barriers and lack of antitrust immunity, and still do so.

On May 14, 1997, an agreement was announced forming the Star Alliance with five airlines on three continents: United Airlines, Scandinavian Airlines, Thai Airways International, Air Canada, and Lufthansa. The alliance chose Young & Rubicam for advertising, with a budget of $25 million (€18 million). which brought competing airlines to form Oneworld in 1999 and SkyTeam in 2000.

In 2010 Richard Branson, chairman of the Virgin Group, announced his intention to form a fourth alliance among Virgin branded airlines (Virgin Atlantic; Virgin America; and the Virgin Australia Holdings group of airlines). Then in September 2011, Branson said that Virgin Atlantic would join one of the existing alliances; this idea was repeated in October 2012. In December 2012, Delta Air Lines purchased Singapore Airlines' 49% stake in Virgin Atlantic for £224 million. Virgin America was absorbed into Alaska Airlines, which joined the Oneworld alliance in 2021.

On February 14, 2013, it was announced that American Airlines and US Airways would merge, retaining the American Airlines name and would remain in the Oneworld alliance. US Airways' participation in Star Alliance lapsed. In 2012, in South America, LAN Airlines and TAM Airlines began their merger. In March 2014, with the merger complete, TAM left Star Alliance and became part of LAN in Oneworld.

On September 21, 2015, the Vanilla Alliance was formed between several airlines based in the Indian Ocean region, in order to improve air connectivity within the region. The founding members are Air Austral, Air Mauritius, Air Madagascar, Air Seychelles, and Int'Air Îles.

On January 18, 2016, the first alliance of low-cost carriers was formed, U-FLY Alliance. The founding members—HK Express, Lucky Air, Urumqi Air, and West Air—are all affiliated with HNA Group, although the alliance is also seeking airlines not within the group.

On May 16, 2016, the world's largest alliance of low-cost carriers was formed, Value Alliance. The founding members were Cebu Pacific, Cebgo, Jeju Air, Nok Air, NokScoot, Scoot Airlines, Tigerair, Tigerair Australia, and Vanilla Air.

Star Alliance

Star Alliance, founded in 1997, currently has 26 members:

Aegean Airlines, 2010 🇨🇦 Air Canada, founder 🇨🇳 Air China, 2007 🇮🇳 Air India, 2014 🇳🇿 Air New Zealand, 1999 🇯🇵 All Nippon Airways, 1999 🇰🇷 Asiana Airlines, 2003 🇦🇹 Austrian Airlines, 2000 🇨🇴 Avianca, 2012 🇧🇪 Brussels Airlines, 2009 🇵🇦 Copa Airlines, 2012 Croatia Airlines, 2004 🇪🇬 EgyptAir, 2008 🇪🇹 Ethiopian Airlines, 2011 🇹🇼 EVA Air, 2013 🇵🇱 LOT Polish Airlines, 2003 🇩🇪 Lufthansa, founder 🇩🇰 🇳🇴 🇸🇪 Scandinavian Airlines, founder, leaving the alliance on August 31, 2024 and joins Skyteam from September 1, 2024 🇨🇳 Shenzhen Airlines, 2012 Singapore Airlines, 2000 South African Airways, 2006 Swiss International Air Lines, 2006 TAP Air Portugal, 2005 🇹🇭 Thai Airways International, founder 🇹🇷 Turkish Airlines, 2008 🇺🇸 United Airlines, founder

Former members: • Adria Airways, 2004–2019, defunct

• 🇦🇺 Ansett Australia, 1999–2001, defunct

• 🇫🇮 Blue1, 2004–2012, defunct

• 🇬🇧 BMI, 2000–2012, absorbed into British Airways

• 🇺🇸 Continental Airlines, 2009–2012, merged with United Airlines

• 🇲🇽 Mexicana de Aviación, 2000–2004, joined Oneworld in 2009

• 🇨🇳 Shanghai Airlines, 2007–2010, merged with China Eastern Airlines and joined SkyTeam in 2011

• 🇪🇸 Spanair, 2003–2012, defunct

• 🇸🇻 TACA, 2012–2013, merged with Avianca

• 🇧🇷 Avianca Brazil, 2015–2019, defunct

• 🇧🇷 TAM Airlines, 2010–2014, merged with LAN Airlines and joined Oneworld in 2014

• 🇺🇸 US Airways, 2004–2014, joined Oneworld as an affiliate member of American Airlines

• 🇧🇷 Varig, 1997–2007, defunct

Star Alliance Connecting Partners

 * 🇨🇳 Juneyao Air, 2017

Star Alliance Intermodal Partnership

 * 🇩🇪 Deutsche Bahn, 2022

Oneworld

Oneworld, founded in 1999, currently has 13 members:

🇺🇸 Alaska Airlines, 2021 🇺🇸 American Airlines, founder 🇬🇧 British Airways, founder 🇭🇰 Cathay Pacific, founder 🇫🇮 Finnair, 1999 🇪🇸 Iberia Airlines, 1999 🇯🇵 Japan Airlines, 2007 🇲🇾 Malaysia Airlines, 2013 🇦🇺 Qantas, founder 🇶🇦 Qatar Airways, 2013 🇲🇦 Royal Air Maroc, 2020 🇯🇴 Royal Jordanian, 2007 🇱🇰 SriLankan Airlines, 2014

Former members:

• 🇮🇪 Aer Lingus, 2000–2007, left the alliance

• 🇩🇪 Air Berlin, 2012–2017, defunct

• 🇨🇦 Canadian Airlines, founder, 1999–2000, acquired by Air Canada

• 🇧🇷 LATAM Brasil, 2014–2020

• 🇨🇱 LATAM Chile, 2000–2020

• 🇭🇺 Malév Hungarian Airlines, 2007–2012, defunct

• 🇲🇽 Mexicana de Aviación, 2009 (ceased operations in 2010)

• 🇷🇺 S7 Airlines, 2010–2022, suspended from alliance

• 🇺🇸 US Airways, 2014–2015, merged with American AirlinesFuture member:

 * Oman Air, joining in 2024
 * 🇫🇯 Fiji Airways, joining in 2025 (currently as Oneworld Connect Partners)

SkyTeam

SkyTeam, founded in 2000, currently has 19 members:

🇦🇷 Aerolíneas Argentinas, 2012 🇲🇽 Aeroméxico, founder 🇪🇸 Air Europa, 2007 🇫🇷 Air France, founder 🇹🇼 China Airlines, 2011 🇨🇳 China Eastern Airlines, 2011 🇨🇿 Czech Airlines, 2001 🇺🇸 Delta Air Lines, founder 🇮🇩 Garuda Indonesia, 2014 🇮🇹 ITA Airways, 2021 🇰🇪 Kenya Airways, 2007 🇳🇱 KLM Royal Dutch Airlines, 2004 🇰🇷 Korean Air, founder

🇱🇧 Middle East Airlines, 2012

🇸🇦 Saudia, 2012

TAROM, 2010

🇻🇳 Vietnam Airlines, 2010

🇬🇧 Virgin Atlantic, 2023

🇨🇳 XiamenAir, 2012

Former members:

• 🇷🇺 Aeroflot, 2006–2022, suspended from alliance

• 🇮🇹 Alitalia, 2001–2021, defunct

• 🇨🇳 China Southern Airlines, 2007–2018

• 🇺🇸 Continental Airlines, 2004–2009, joined Star Alliance in 2009

• 🇵🇦 Copa Airlines, 2007–2009, joined Star Alliance in 2012

• 🇺🇸 Northwest Airlines, 2004–2010, merged with Delta Air Lines

Vanilla Alliance
Vanilla Alliance, founded in 2015, currently has 5 members:

🇷🇪 Air Austral, founder 🇲🇬 Air Madagascar, founder 🇲🇺 Air Mauritius, founder 🇸🇨 Air Seychelles, founder 🇰🇲 Int'Air Îles, founder

U-FLY Alliance
U-FLY Alliance, founded in 2016, currently has 4 members:

🇰🇷 Eastar Jet, 2016 🇨🇳 Lucky Air, founder 🇨🇳 Urumqi Air, founder 🇨🇳 West Air, founder

Former members:
 * 🇭🇰 HK Express, 2016-2019, founder, acquired by Cathay Pacific in 2019.

Value Alliance
Value Alliance, founded in 2016, currently has 5 members:

🇵🇭 Cebu Pacific, founder 🇵🇭 Cebgo, founder 🇰🇷 Jeju Air, founder 🇹🇭 Nok Air, founder 🇸🇬 Scoot, founder

Former members:
 * 🇹🇭 NokScoot, 2016–2020, defunct
 * Tigerair, 2016–2017, merged with Scoot
 * 🇦🇺 Tigerair Australia, 2016–2018, founder
 * 🇯🇵 Vanilla Air, 2016–2018, founder, merged with Peach Aviation

title: Airline alliance


text:
Single-suit squeeze

A single-suit squeeze is a unique squeeze play in contract bridge that occurs with an awkward defensive distribution of one suit. It is a kind of immaterial squeeze, in which a discard does not cost a trick directly, but gives up a position, allowing the opponents to adopt a winning line.

Example
The first example is a one-suit squeeze in which the victim can choose between an endplay or a simple promotion: If the five of diamonds is played, East must choose whether to discard the spade three or an intermediate honor. By throwing the three East chooses an endplay; South simply ducks a small spade to East, who has to lead up to the king. By throwing an intermediate honor, East allows for a promotion of the eight; South leads the nine, West has to cover in order to avoid an endplay and the eight will eventually become master. Note that if the spade five and three were exchanged the squeeze still works. East can choose between an endplay to the king, or an endplay to the eight.

title: Single-suit squeeze


text:
Old Salt Route

The Old Salt Route was a medieval trade route in Northern Germany, one of the ancient network of salt roads which were used primarily for the transport of salt and other staples. In Germany it was referred to as Alte Salzstraße.

Salt was very valuable and essential at that time; it was sometimes referred to as "white gold." The vast majority of the salt transported on the road was produced from brine near Lüneburg, a city in the northern central part of the country and then transported to Lübeck, a major seaport on Germany's Baltic Sea coast.

History
Historians generally recognize the Old Salt Route as part of a much longer path, which functioned as an important connection between the northern and southern reaches of the country. One of the oldest documents that confirms Lüneburg and its role in refining and transporting salt dates from 956 A.D. According to that document, King Otto I the Great granted the St. Michaelis Monastery in Lüneburg the customs revenue from the saltworks. Even at those early times, the city's wealth was based in large part on the salt found in the area. The Old Salt Route attained its peak of success between the 12th and the 16th century.

The trade route led from Lüneburg northward to Lübeck. From that port city, most of the salt was shipped to numerous destinations that also lie on the Baltic Sea, including Falsterbo, which boasted a Scania Market. There it was used for the preservation of herring, an immensely important food in the Middle Ages, as well as for other foods. The salt trade was a major reason for the power of Lübeck and the Hanseatic League.

Transport of salt
Horse-drawn carts brought the salt from Lüneburg to a crossing of the Elbe river at Artlenburg (near Lauenburg) and from there, via Mölln, to Lübeck. For the most part, however, the historic trade route was composed of unsurfaced, sandy and often muddy roads through heathland, woods and small villages, making the transport of salt an arduous task. In addition, the route was somewhat dangerous, since the valuable cargo attracted thieves, bandits and marauders. The dangers faced by those who make the long trek and the fact that only relatively small quantities of the precious crystalline substance could be carried in any single journey, made moving salt via overland routes very expensive.

In 1398, though, the Stecknitz Canal, one of the first manmade waterways in Europe, was completed, making it possible to transport much more salt in a single shipment and to do so with much greater ease and safety. That change helped merchants satisfy the salt requirements of an ever-growing demand. In the 16th century, for example, about 19,000 tons of the product were carried from Lüneburg to Lübeck each year either by land or water. However, it still took about twenty days to complete each trip.

Tourism
In modern times, a trip along the Salt Road promises a rich blend of nature and culture. The trip can be made on foot or on bicycle and part of the distance can also be enjoyed on a paddle-wheeled steamer. There are many fascinating sights along the old trade route. These points of interest include the historical towns Lüneburg, Mölln and Lübeck, which are highlighted by beautiful façades and little alleyways, and are a major attraction to visitors.

Bicycle route
As a bicycle route, there are the options of a main and a scenic route. The shorter main route (95 km) leads bicyclists through many picturesque little towns such as Lauenburg, Büchen, Mölln and Krummsee and also passes by the Lüne Monastery. The scenic route is especially attractive for nature lovers. The 106 km path diverges from the main thoroughfare at Witzeeze, continues on through the Lauenburg Nature Park and rejoins the main route just before Lübeck.

Lüneburg Heath

Once, the area around Lüneburg was covered in lush woodlands. But because the medieval salt works depended on wood as a fuel used in boiling and purifying the saline water from which the salt was obtained, much of the forest was cut down. Heather then covered area, helping it to become a landscape that now attracts thousands of visitors when that foliage is in full bloom.

title: Old Salt Route


text:
Criss-cross squeeze

In contract bridge, the criss-cross squeeze is a variant of the simple squeeze in which both menaces are blocked. However, the blocking cards provide the necessary communication between hands after the squeeze has been effected. Unblocking in the correct order allows the squeezing player to cash the newly created winner; but this requires an exact count of the hand – or a correct guess.

Examples
The menaces are the major-suit queens, blocked by the corresponding aces. One of those aces will serve as entry or re-entry to whichever queen is established by the squeeze. When South cashes the A as squeeze card, West must blank (unguard) one of his kings. The declarer can then cash the ace of the suit in which West has bared his king, and cross to the other ace, which serves as entry to the now-established queen.

A criss-cross squeeze is technically an automatic squeeze, i.e. it works against either opponent – although a guess as to which opponent (if either) has been squeezed may be required in the end position after playing the squeeze card (here, A). If the complete hand is as shown here, then East is squeezed; but if declarer cannot be certain from the previous bidding and play who holds both kings, he will have to guess which suit to play first if the defenders discard in different suits (as they should).

If the kings are in different hands, there is no squeeze: both defenders will have idle cards to discard in the suit in which they do not hold a king.

title: Criss-cross squeeze


text:
Biomechanics

Biomechanics is the study of the structure, function and motion of the mechanical aspects of biological systems, at any level from whole organisms to organs, cells and cell organelles, using the methods of mechanics. Biomechanics is a branch of biophysics.

Today computational mechanics goes far beyond pure mechanics, and involves other physical actions: chemistry, heat and mass transfer, electric and magnetic stimuli and many others.

Etymology
The word "biomechanics" (1899) and the related "biomechanical" (1856) come from the Ancient Greek βίος bios "life" and μηχανική, mēchanikē "mechanics", to refer to the study of the mechanical principles of living organisms, particularly their movement and structure.

Biofluid mechanics

Biological fluid mechanics, or biofluid mechanics, is the study of both gas and liquid fluid flows in or around biological organisms. An often studied liquid biofluid problem is that of blood flow in the human cardiovascular system. Under certain mathematical circumstances, blood flow can be modeled by the Navier–Stokes equations. In vivo whole blood is assumed to be an incompressible Newtonian fluid. However, this assumption fails when considering forward flow within arterioles. At the microscopic scale, the effects of individual red blood cells become significant, and whole blood can no longer be modeled as a continuum. When the diameter of the blood vessel is just slightly larger than the diameter of the red blood cell the Fahraeus–Lindquist effect occurs and there is a decrease in wall shear stress. However, as the diameter of the blood vessel decreases further, the red blood cells have to squeeze through the vessel and often can only pass in a single file. In this case, the inverse Fahraeus–Lindquist effect occurs and the wall shear stress increases.

An example of a gaseous biofluids problem is that of human respiration. Recently, respiratory systems in insects have been studied for bioinspiration for designing improved microfluidic devices.

Biotribology
Biotribology is the study of friction, wear and lubrication of biological systems, especially human joints such as hips and knees. In general, these processes are studied in the context of contact mechanics and tribology.

Additional aspects of biotribology include analysis of subsurface damage resulting from two surfaces coming in contact during motion, i.e. rubbing against each other, such as in the evaluation of tissue-engineered cartilage.

Comparative biomechanics
Comparative biomechanics is the application of biomechanics to non-human organisms, whether used to gain greater insights into humans (as in physical anthropology) or into the functions, ecology and adaptations of the organisms themselves. Common areas of investigation are Animal locomotion and feeding, as these have strong connections to the organism's fitness and impose high mechanical demands. Animal locomotion, has many manifestations, including running, jumping and flying. Locomotion requires energy to overcome friction, drag, inertia, and gravity, though which factor predominates varies with environment.

Comparative biomechanics overlaps strongly with many other fields, including ecology, neurobiology, developmental biology, ethology, and paleontology, to the extent of commonly publishing papers in the journals of these other fields. Comparative biomechanics is often applied in medicine (with regards to common model organisms such as mice and rats) as well as in biomimetics, which looks to nature for solutions to engineering problems.

Computational biomechanics
Computational biomechanics is the application of engineering computational tools, such as the Finite element method to study the mechanics of biological systems. Computational models and simulations are used to predict the relationship between parameters that are otherwise challenging to test experimentally, or used to design more relevant experiments reducing the time and costs of experiments. Mechanical modeling using finite element analysis has been used to interpret the experimental observation of plant cell growth to understand how they differentiate, for instance. In medicine, over the past decade, the Finite element method has become an established alternative to in vivo surgical assessment. One of the main advantages of computational biomechanics lies in its ability to determine the endo-anatomical response of an anatomy, without being subject to ethical restrictions. This has led FE modeling (or other discretization techniques) to the point of becoming ubiquitous in several fields of Biomechanics while several projects have even adopted an open source philosophy (e.g. BioSpine) and SOniCS, as well as the SOFA, FEniCS frameworks and FEBio.

Computational biomechanics is an essential ingredient in surgical simulation, which is used for surgical planning, assistance and training. In this case, numerical (discretization) methods are used to compute, as fast as possible, the response of a system to boundary conditions such as forces, heat and mass transfer, electrical and magnetic stimuli.

Continuum biomechanics
The mechanical analysis of biomaterials and biofluids is usually carried forth with the concepts of continuum mechanics. This assumption breaks down when the length scales of interest approach the order of the micro structural details of the material. One of the most remarkable characteristic of biomaterials is their hierarchical structure. In other words, the mechanical characteristics of these materials rely on physical phenomena occurring in multiple levels, from the molecular all the way up to the tissue and organ levels.

Biomaterials are classified in two groups, hard and soft tissues. Mechanical deformation of hard tissues (like wood, shell and bone) may be analysed with the theory of linear elasticity. On the other hand, soft tissues (like skin, tendon, muscle and cartilage) usually undergo large deformations and thus their analysis rely on the finite strain theory and computer simulations. The interest in continuum biomechanics is spurred by the need for realism in the development of medical simulation.

Neuromechanics
Neuromechanics uses a biomechanical approach to better understand how the brain and nervous system interact to control the body. During a motor tasks, motor units will activate a set of muscles to perform a specific movement, which can be modified via motor adaptation and learning. In recent years, neuromechanical experiments have been enabled by combining motion capture tools with neural recordings.

Plant biomechanics
The application of biomechanical principles to plants, plant organs and cells has developed into the subfield of plant biomechanics. Application of biomechanics for plants ranges from studying the resilience of crops to environmental stress to development and morphogenesis at cell and tissue scale, overlapping with mechanobiology.

Sports biomechanics
In sports biomechanics, the laws of mechanics are applied to human movement in order to gain a greater understanding of athletic performance and to reduce sport injuries as well. It focuses on the application of the scientific principles of mechanical physics to understand movements of action of human bodies and sports implements such as cricket bat, hockey stick and javelin etc. Elements of mechanical engineering (e.g., strain gauges), electrical engineering (e.g., digital filtering), computer science (e.g., numerical methods), gait analysis (e.g., force platforms), and clinical neurophysiology (e.g., surface EMG) are common methods used in sports biomechanics.

Biomechanics in sports can be stated as the muscular, joint and skeletal actions of the body during the execution of a given task, skill and/or technique. Proper understanding of biomechanics relating to sports skill has the greatest implications on: sport's performance, rehabilitation and injury prevention, along with sport mastery. As noted by Doctor Michael Yessis, one could say that best athlete is the one that executes his or her skill the best.

Vascular biomechanics
The main topics of the vascular biomechanics is the description of the mechanical behaviour of vascular tissues.

It is well known that cardiovascular disease is the leading cause of death worldwide. Vascular system in the human body is the main component that is supposed to maintain pressure and allow for blood flow and chemical exchanges. Studying the mechanical properties of this complex tissues improves the possibility to better understanding cardiovascular diseases and drastically improve personalized medicine.

Vascular tissues are inhomogeneous with a strongly non linear behaviour. Generally this study involves complex geometry with intricate load conditions and material properties. The correct description of these mechanisms is based on the study of physiology and biological interaction. Therefore is necessary to study wall mechanics and hemodynamics with their interaction.

It is also necessary to premise that the vascular wall is a dynamic structure in continuous evolution. This evolution directly follows the chemical and mechanical environment in which the tissues are immersed like Wall Shear Stress or biochemical signaling.

Immunomechanics
The emerging field of immunomechanics focuses on characterising mechanical properties of the immune cells and their functional relevance. Mechanics of immune cells can be characterised using various force spectroscopy approaches such as acoustic force spectroscopy and optical tweezers, and these measurements can be performed at physiological conditions (e.g. temperature). Furthermore, one can study the link between immune cell mechanics and immunometabolism and immune signalling. The term "immunomechanics" is some times interchangeably used with immune cell mechanobiology or cell mechanoimmunology.

Other applied subfields of biomechanics include

 * Allometry
 * Animal locomotion & Gait analysis
 * Biotribology
 * Biofluid mechanics
 * Cardiovascular biomechanics
 * Comparative biomechanics
 * Computational biomechanics
 * Ergonomy
 * Forensic Biomechanics
 * Human factors engineering & occupational biomechanics
 * Injury biomechanics
 * Implant (medicine), Orthotics & Prosthesis
 * Kinaesthetics
 * Kinesiology (kinetics + physiology)
 * Musculoskeletal & orthopedic biomechanics
 * Rehabilitation
 * Soft body dynamics
 * Sports biomechanics

Antiquity
Aristotle, a student of Plato can be considered the first bio-mechanic, because of his work with animal anatomy. Aristotle wrote the first book on the motion of animals, De Motu Animalium, or On the Movement of Animals. He saw animal's bodies as mechanical systems, pursued questions such as the physiological difference between imagining performing an action and actual performance. In another work, On the Parts of Animals, he provided an accurate description of how the ureter uses peristalsis to carry urine from the kidneys to the bladder.

With the rise of the Roman Empire, technology became more popular than philosophy and the next bio-mechanic arose. Galen (129 AD-210 AD), physician to Marcus Aurelius, wrote his famous work, On the Function of the Parts (about the human body). This would be the world's standard medical book for the next 1,400 years.

Renaissance
The next major biomechanic would not be around until the 1490s, with the studies of human anatomy and biomechanics by Leonardo da Vinci. He had a great understanding of science and mechanics and studied anatomy in a mechanics context. He analyzed muscle forces and movements and studied joint functions. These studies could be considered studies in the realm of biomechanics. Leonardo da Vinci studied anatomy in the context of mechanics. He analyzed muscle forces as acting along lines connecting origins and insertions, and studied joint function. Da Vinci is also known for mimicking some animal features in his machines. For example, he studied the flight of birds to find means by which humans could fly; and because horses were the principal source of mechanical power in that time, he studied their muscular systems to design machines that would better benefit from the forces applied by this animal.

In 1543, Galen's work, On the Function of the Parts was challenged by Andreas Vesalius at the age of 29. Vesalius published his own work called, On the Structure of the Human Body. In this work, Vesalius corrected many errors made by Galen, which would not be globally accepted for many centuries. With the death of Copernicus came a new desire to understand and learn about the world around people and how it works. On his deathbed, he published his work, On the Revolutions of the Heavenly Spheres. This work not only revolutionized science and physics, but also the development of mechanics and later bio-mechanics.

Galileo Galilei, the father of mechanics and part time biomechanic was born 21 years after the death of Copernicus. Over his years of science, Galileo made a lot of biomechanical aspects known. For example, he discovered that "animals' masses increase disproportionately to their size, and their bones must consequently also disproportionately increase in girth, adapting to loadbearing rather than mere size. The bending strength of a tubular structure such as a bone is increased relative to its weight by making it hollow and increasing its diameter. Marine animals can be larger than terrestrial animals because the water's buoyancy relieves their tissues of weight."

Galileo Galilei was interested in the strength of bones and suggested that bones are hollow because this affords maximum strength with minimum weight. He noted that animals' bone masses increased disproportionately to their size. Consequently, bones must also increase disproportionately in girth rather than mere size. This is because the bending strength of a tubular structure (such as a bone) is much more efficient relative to its weight. Mason suggests that this insight was one of the first grasps of the principles of biological optimization.

In the 17th century, Descartes suggested a philosophic system whereby all living systems, including the human body (but not the soul), are simply machines ruled by the same mechanical laws, an idea that did much to promote and sustain biomechanical study.

Industrial era
The next major bio-mechanic, Giovanni Alfonso Borelli, embraced Descartes' mechanical philosophy and studied walking, running, jumping, the flight of birds, the swimming of fish, and even the piston action of the heart within a mechanical framework. He could determine the position of the human center of gravity, calculate and measure inspired and expired air volumes, and he showed that inspiration is muscle-driven and expiration is due to tissue elasticity.

Borelli was the first to understand that "the levers of the musculature system magnify motion rather than force, so that muscles must produce much larger forces than those resisting the motion". Influenced by the work of Galileo, whom he personally knew, he had an intuitive understanding of static equilibrium in various joints of the human body well before Newton published the laws of motion. His work is often considered the most important in the history of bio-mechanics because he made so many new discoveries that opened the way for the future generations to continue his work and studies.

It was many years after Borelli before the field of bio-mechanics made any major leaps. After that time, more and more scientists took to learning about the human body and its functions. There are not many notable scientists from the 19th or 20th century in bio-mechanics because the field is far too vast now to attribute one thing to one person. However, the field is continuing to grow every year and continues to make advances in discovering more about the human body. Because the field became so popular, many institutions and labs have opened over the last century and people continue doing research. With the Creation of the American Society of Bio-mechanics in 1977, the field continues to grow and make many new discoveries.

In the 19th century Étienne-Jules Marey used cinematography to scientifically investigate locomotion. He opened the field of modern 'motion analysis' by being the first to correlate ground reaction forces with movement. In Germany, the brothers Ernst Heinrich Weber and Wilhelm Eduard Weber hypothesized a great deal about human gait, but it was Christian Wilhelm Braune who significantly advanced the science using recent advances in engineering mechanics. During the same period, the engineering mechanics of materials began to flourish in France and Germany under the demands of the industrial revolution. This led to the rebirth of bone biomechanics when the railroad engineer Karl Culmann and the anatomist Hermann von Meyer compared the stress patterns in a human femur with those in a similarly shaped crane. Inspired by this finding Julius Wolff proposed the famous Wolff's law of bone remodeling.

Applications
The study of biomechanics ranges from the inner workings of a cell to the movement and development of limbs, to the mechanical properties of soft tissue, and bones. Some simple examples of biomechanics research include the investigation of the forces that act on limbs, the aerodynamics of bird and insect flight, the hydrodynamics of swimming in fish, and locomotion in general across all forms of life, from individual cells to whole organisms. With growing understanding of the physiological behavior of living tissues, researchers are able to advance the field of tissue engineering, as well as develop improved treatments for a wide array of pathologies including cancer.

Biomechanics is also applied to studying human musculoskeletal systems. Such research utilizes force platforms to study human ground reaction forces and infrared videography to capture the trajectories of markers attached to the human body to study human 3D motion. Research also applies electromyography to study muscle activation, investigating muscle responses to external forces and perturbations.

Biomechanics is widely used in orthopedic industry to design orthopedic implants for human joints, dental parts, external fixations and other medical purposes. Biotribology is a very important part of it. It is a study of the performance and function of biomaterials used for orthopedic implants. It plays a vital role to improve the design and produce successful biomaterials for medical and clinical purposes. One such example is in tissue engineered cartilage. The dynamic loading of joints considered as impact is discussed in detail by Emanuel Willert.

It is also tied to the field of engineering, because it often uses traditional engineering sciences to analyze biological systems. Some simple applications of Newtonian mechanics and/or materials sciences can supply correct approximations to the mechanics of many biological systems. Applied mechanics, most notably mechanical engineering disciplines such as continuum mechanics, mechanism analysis, structural analysis, kinematics and dynamics play prominent roles in the study of biomechanics. Usually biological systems are much more complex than man-built systems. Numerical methods are hence applied in almost every biomechanical study. Research is done in an iterative process of hypothesis and verification, including several steps of modeling, computer simulation and experimental measurements.

title: Biomechanics