Background.

Autoacceleration of the overall rate of a free-radical polymerization system has been noted in many bulk polymerization systems. The polymerization of methyl methacrylate, for example, deviates strongly from classical mechanism behavior around 20% conversion; in this region the conversion and molecular mass of the polymer produced increases rapidly. This increase of polymerization is usually accompanied by a large rise in temperature if heat dissipation is not adequate. Without proper precautions, autoacceleration of polymerization systems could cause metallurgic failure of the reaction vessel or, worse, explosion.  To avoid the occurrence of thermal runaway due to autoacceleration, suspension polymerization techniques are employed to make polymers such as polystyrene. The droplets dispersed in the water are small reaction vessels, but the heat capacity of the water lowers the temperature rise, thus moderating the reaction.

Causes.

Norrish and Smith, Trommsdorff, and later, Schultz and Harborth, concluded that autoacceleration must be caused by a totally different polymerization mechanism. They rationalized through experiment that a decrease in the termination rate was the basis of the phenomenon. This decrease in termination rate, "k", is caused by the raised viscosity of the polymerization region when the concentration of previously formed polymer molecules increases. Before autoacceleration, chain termination by combination of two free-radical chains is a very rapid reaction that occurs at very high frequency (about one in 10 collisions). However, when the growing polymer molecules – with active free-radical ends – are surrounded in the highly viscous mixture consisting of a growing concentration of "dead" polymer, the rate of termination becomes limited by diffusion. The Brownian motion of the larger molecules in the polymer "soup" is restricted, therefore limiting the frequency of their effective (termination) collisions.

Results.

With termination collisions restricted, the concentration of active polymerizing chains and simultaneously the consumption of monomer rises rapidly. Assuming abundant unreacted monomer, viscosity changes affect the macromolecules but do not prove high enough to prevent smaller molecules – such as the monomer – from moving relatively freely. Therefore, the propagation reaction of the free-radical polymerization process is relatively insensitive to changes in viscosity. This also implies that at the onset of autoacceleration the overall rate of reaction increases relative to the rate of unautoaccelerated reaction given by the overall rate of reaction equation for free-radical polymerization:  Approximately, as the termination decreases by a factor of 4, the overall rate of reaction will double. The decrease of termination reactions also allows radical chains to add monomer for longer time periods, raising the mass-average molecular mass dramatically. However, the number-average molecular mass only increases slightly, leading to broadening of the molecular mass distribution (high dispersity, very polydispersed product).

Autoacceleration (gel effect, Trommsdorff–Norrish effect) is a dangerous reaction behavior that can occur in free-radical polymerization systems. It is due to the localized increases in viscosity of the polymerizing system that slow termination reactions. The removal of reaction obstacles therefore causes a rapid increase in the overall rate of reaction, leading to possible reaction runaway and altering the characteristics of the polymers produced.

自动加速现象(autoacceleration),又称凝胶效应,是聚合反应进行到一定程度时,聚合速率显著上升的一种现象。


Signs and symptoms.

Like many other genetic disorders that affect lipid metabolism, there are several forms of MLD, which are late infantile, juvenile, and adult.  Palliative care can help with many of the symptoms and usually improves quality of life and longevity.  Carriers have low enzyme levels compared to their family population ("normal" levels vary from family to family) but even low enzyme levels are adequate to process the body's sulfatide.

Causes.

MLD is directly caused by a deficiency of the enzyme arylsulfatase A (ARSA) and is characterized by enzyme activity in leukocytes that is less than 10% of normal controls. However, assay of the ARSA enzyme activity alone is not sufficient for diagnosis; ARSA pseudodeficiency, which is characterized by enzyme activity that is 5~20% of normal controls does not cause MLD. Without this enzyme, sulfatides build up in many tissues of the body, eventually destroying the myelin sheath of the nervous system. The myelin sheath is a fatty covering that protects nerve fibers. Without it, the nerves in the brain (central nervous system – CNS) and the peripheral nerves (peripheral nervous system – PNS) which control, among other things the muscles related to mobility, cease to function properly.  Arylsulfatase A is activated by saposin B (Sap B), a non-enzymatic proteinaceous cofactor. When the arylsulfatase A enzyme level is normal but the sulfatides are still high – meaning that they are not being broken down because the enzyme is not activated – the resulting disease is saposin B deficiency, which presents similar to MLD. Saposin B Deficiency is very rare, much more rare than traditional MLD. The enzyme that is present is not "enabled" to a normal level of efficiency and can't break down the sulfatides which results in all of the same MLD symptoms and progression.  A 2011 study contended sulfatide is not completely responsible for MLD because it is nontoxic. It has been suggested lysosulfatide, sulfatide which has had its acyl group removed, plays a role because of its cytotoxic properties in vitro.

Genetics.

MLD has an autosomal recessive inheritance pattern. The inheritance probabilities "per birth" are as follows:  In addition to these frequencies there is a 'pseudo'-deficiency that affects 7–15% of the population.<ref name="147-150, DOI: 10.1007/BF00286589"></ref> People with the pseudo deficiency do not have any MLD problems unless they also have affected status. With the current diagnostic tests, Pseudo-deficiency reports as low enzyme levels but sulfatide is processed normally so MLD symptoms do not exist. This phenomenon wreaks havoc with traditional approaches to Newborn Screening so new screening methods are being developed. "For further information, see recessive gene and dominance relationship. Also, consult the MLD genetics page at MLD Foundation. [revise or delete]"

Diagnosis.

Clinical examination and MRI are often the first steps in a MLD diagnosis. MRI can be indicative of MLD, but is not adequate as a confirming test.  An ARSA-A enzyme level blood test with a confirming urinary sulfatide test is the best biochemical test for MLD. The confirming urinary sulfatide is important to distinguish between MLD and pseudo-MLD blood results.  Genomic sequencing may also confirm MLD, however, there are likely more mutations than the over 200 already known to cause MLD that are not yet ascribed to MLD that cause MLD so in those cases a biochemical test is still warranted.  "For further information, see the MLD Testing page at MLD Foundation."

Treatment.

There is currently no therapy or cure for MLD in late infantile patients displaying symptoms, or for juvenile and adult onset with advanced symptoms. These patients typically receive clinical treatment focused on pain and symptom management.  Pre-symptomatic late infantile MLD patients, as well as those with juvenile or adult MLD that are either presymptomatic or displaying mild symptoms, can consider bone marrow transplantation (including stem cell transplantation), which may slow down progression of the disease in the central nervous system. However, results in the peripheral nervous system have been less dramatic, and the long-term results of these therapies have been mixed. Recent success has involved stem cells being taken from the bone marrow of children with the disorder and infecting the cells with a retro-virus, replacing the stem cells' mutated gene with the repaired gene before re-injecting it back into the patient where they multiplied. The children by the age of five were all in good condition and going to kindergarten when normally by this age, children with the disease can not even speak.  Several therapy options are currently being investigated using clinical trials primarily in late infantile patients. These therapies include gene therapy, enzyme replacement therapy (ERT), substrate reduction therapy (SRT), and potentially enzyme enhancement therapy (EET).  A team of international researchers and foundations gathered in 2008 to form an international MLD Registry to create and manage a shared repository of knowledge, including the natural history of MLD. This consortium consisted of scientific, academic and industry resources. This registry never became operational.

Epidemiology.

The incidence of metachromatic leukodystrophy is estimated to occur in 1 in 40,000 to 1 in 160,000 individuals worldwide. There is a much higher incidence in certain genetically isolated populations, such as 1 in 75 in Habbanites (a small group of Jews who immigrated to Israel from southern Arabia), 1 in 2,500 in the western portion of the Navajo Nation, and 1 in 8,000 among Arab groups in Israel.  As an autosomal recessive disease, 1 in 40,000 equates to a 1 in 100 carrier frequency in the general population.  There are an estimated 3,600 MLD births per year, with 1,900 alive in the US, 3,100 in Europe, and 49,000 alive worldwide with MLD.  MLD is considered a rare disease in the US and other countries.

Research.

Gene therapy.

"(current as of January 2017)" Two different approaches to gene therapy are currently being researched for MLD.

Enzyme replacement therapy (ERT).

"(current as of January 2017)"  More information here "(current January 2017)"

Natural history studies.

"Research & Clinical Trial updates provided by MLD Foundation

Metachromatic leukodystrophy (MLD) is a lysosomal storage disease which is commonly listed in the family of leukodystrophies as well as among the sphingolipidoses as it affects the metabolism of sphingolipids. Leukodystrophies affect the growth and/or development of myelin, the fatty covering which acts as an insulator around nerve fibers throughout the central and peripheral nervous systems. MLD involves cerebroside sulfate accumulation. Metachromatic leukodystrophy, like most enzyme deficiencies, has an autosomal recessive inheritance pattern.

异染性脑白质退化症(英语:Meta-chromatic leuko-dystrophy、英语:MLD,亦称:异染性脑白质营养不良症、英语:芳基硫酸酯酶A缺乏症<英语:Arylsulfatase A deficiency/ARSA deficiency>、英语:Greenfield's disease)为一种溶酶体贮积症(lysosomal storage disease),将MLD的神经纤维切片以结晶紫染色结果不呈紫色而呈黄褐色、故名之"异染性"(meta-chromatic),一般归于脑白质营养不良(leukodystrophies)的类别、同于鞘脂质代谢障碍(sphingolipidoses),因其影响神经鞘脂质(sphingolipids)的代谢。而脑白质营养不良影响髓磷脂的"生长"和/或"发展",而"脂质"的被覆是作为周围神经纤维的"阻隔体"(insulator)贯穿整个中枢和外周的神经系统。MLD亦涉及脑苷脂的积累。 异染性脑白质退化症、如同大多数的"酶缺陷"(enzyme deficiency)一样,存有「常染色体隐性遗传模式」。


阿纳托利·费奥多罗维奇·多勃雷宁

Early life and education.

Dobrynin was born in the village of Krasnaya Gorka, near Mozhaisk in the Moscow Oblast, on 16 November 1919. His father was a locksmith. He attended the Moscow Aviation Institute and after graduation went to work for the Yakovlev Design Bureau. He entered the Higher Diplomatic School in 1944 and graduated with distinction.

Career.

Dobrynin joined the diplomatic service of the Ministry of Foreign Affairs in 1946. He later joined the secretariat of the ministry, working for Vyacheslav Molotov, Dmitri Shepilov, Andrei Gromyko and Valerian Zorin. He was appointed deputy secretary general at the United Nations in 1957 and returned to Moscow as head of the foreign ministry's department of the United States and Canada in 1960. Dobrynin was appointed as Soviet Ambassador to the United States in 1962, and he had been the Dean of the Diplomatic Corps since July 1979. His tenure lasted until 1986.  Anatoly Dobrynin had the unique experience of serving as Soviet Ambassador to the US during the terms of six US Presidents (Kennedy, Johnson, Nixon, Ford, Carter and Reagan). The Cold War rivalry made his position one of the key elements in Soviet Union–United States relations, such that between the Soviet Ambassador to the United States (in Washington) and the United States Ambassador to the Soviet Union (in Moscow), most diplomatic business channeled through the former. Dobrynin's regular contacts with the US State Department resulted in him being granted his own parking spot in the State Department garage until 1981, when President Reagan revoked that privilege.  Dobrynin developed an especially close relationship with Henry Kissinger, with whom he often met and dined with up to four times a week. They had a direct line to each other's office; they exchanged gifts, shared inside jokes, and even met each other's parents.  In 1971, he was elected to the Central Committee of the Communist Party (CPSU). After his long term as Ambassador to the United States, he returned to Moscow in 1986, joining the Secretariat of the party and leading the international department of the CPSU Central Committee for two years. At the end of 1988, he retired from the Central Committee and served as an advisor to the Soviet Presidency.  He attended the December 1989 Malta Summit that formally marked the end of the Cold War. He was given the honorary rank of Russian Ambassador Extraordinary and Plenipotentiary in 1992.

Works and death.

His book, "In Confidence: Moscow's Ambassador to Six Cold War Presidents", was published in 1995. (It was last reprinted in 2001 as.)  Dobrynin died in Moscow on 6 April 2010. In a telegram to Dobrynin's family, Russian President Dmitry Medvedev paid tribute to Dobrynin, stating:

Anatoly Fyodorovich Dobrynin (, 16 November 1919 – 6 April 2010) was a Russian statesman and a Soviet diplomat and politician. He was Soviet Ambassador to the United States for more than two decades, from 1962 to 1986.

阿纳托利·费奥多罗维奇·多勃雷宁(,1919年-11月16日-2010年-4月6日),乌克兰人,苏联外交官,苏联驻美国大使,戈尔巴乔夫的国际事务顾问。


Biography.

Thomas Bowdler was born in Box, near Bath, Somerset, the youngest son of the six children of Thomas Bowdler (c. 1719–1785), a banker of substantial fortune, and his wife, Elizabeth, "née" Cotton (d. 1797), the daughter of Sir John Cotton, 6th Baronet of Conington, Huntingdonshire. Bowdler studied medicine at the universities of St. Andrews and Edinburgh, where he received his degree in 1776, graduating with a thesis on intermittent fevers. He spent the next four years travelling through continental Europe, visiting Germany, Hungary, Italy, Sicily, and Portugal. In 1781 he caught a fever in Lisbon from a young friend whom he was attending to through a fatal illness. He returned to England in broken health and with a strong aversion to the medical profession. In 1781 he was elected a Fellow of the Royal Society (FRS) and a Licentiate of the Royal College of Physicians (LRCP), but did not continue to practice medicine. He devoted himself instead to the cause of prison reform.  Bowdler was also a strong chess player and once played eight recorded games against the best chess player of the time, François-André Danican Philidor, who was so confident of his superiority that he played with several handicaps. Bowdler won twice, lost three times, and drew three times. The Bowdler Attack is named after him. Bowdler's first published work was "Letters Written in Holland in the Months of September and October 1787" (1788), which gave his eye-witness account of the Patriots' uprising. In 1800 Bowdler took a lease on a country estate at St. Boniface, on the Isle of Wight, where he lived for ten years. In September 1806, when he was 52, he married Elizabeth Trevenen (née Farquharson), age 48, the widow of the naval officer Captain James Trevenen who had died in Catherine the Great's service at Kronstadt in 1790. The marriage was unhappy, and after a few years Bowdler and his wife separated. They had no children. After the separation, the marriage was never mentioned by the Bowdler family; in the biography of Bowdler written by his nephew, Thomas Bowdler, there is no mention of Bowdler ever marrying.  In 1807, the first edition of the Bowdlers' "The Family Shakspeare," covering 20 plays, was published in four small volumes. From 1811 until his death in 1825, Bowdler lived at Rhyddings House, overlooking Swansea Bay, from where he travelled extensively in Britain and continental Europe. In 1815, he published "Observations on Emigration to France, With an Account of Health, Economy, and the Education of Children", a cautionary work propounding his view that English invalids should avoid French spas and go instead to Malta. In 1818, Bowdler published an expanded edition of "The Family Shakspeare", covering all 36 available plays, which had considerable success. By 1827 the work had gone into its fifth edition. In his last years, Bowdler prepared an expurgated version of the works of the historian Edward Gibbon, which was published posthumously in 1826. His sister Jane Bowdler (1743–1784) was a poet and essayist, and another sister, Henrietta Maria Bowdler (Harriet) (1750–1830), collaborated with Bowdler on his expurgated Shakespeare.  Bowdler died in Swansea at the age of 70 and was buried there, at Oystermouth. He bequeathed donations to the poor of Swansea and Box. His large library, consisting of unexpurgated volumes of 17th and 18th century tracts, collected by his ancestors Thomas Bowdler (1638–1700) and Thomas Bowdler (1661–1738), was donated to the University of Wales, Lampeter. In 1825 Bowdler's nephew, also called Thomas Bowdler, published his "Memoir of the Late John Bowdler, Esq., to Which Is Added, Some Account of the Late Thomas Bowdler, Esq. Editor of the Family Shakspeare".

"The Family Shakespeare".

In Bowdler's childhood, his father had entertained his family with readings from Shakespeare. Later in life, Bowdler realized that his father had been omitting or altering passages he felt unsuitable for the ears of his wife and children. Bowdler felt it would be worthwhile to publish an edition which might be used in a family whose father was not a sufficiently "circumspect and judicious reader" to accomplish this expurgation himself.  In 1807 the first edition of the Bowdlers' "The Family Shakspeare" was published in four duodecimo volumes, containing 24 plays. In 1818 the second edition, covering all 36 available plays, was published. Each play is preceded by an introduction wherein Bowdler summarizes and justifies his changes to the text. According to his nephew's "Memoir," the first edition was prepared by Bowdler's sister, Harriet, but both were published under Thomas Bowdler's name. This was likely because a woman could not then publicly admit that she was capable of such editing and compilation, nor that she understood Shakespeare's racy verses. By 1850 eleven editions had been printed.  The spelling "Shakspeare", used by Bowdler and also by his nephew Thomas in his memoir of Thomas Bowdler the elder, was changed in later editions (from 1847 on) to "Shakespeare", reflecting changes in the standard spelling of Shakespeare's name.  The Bowdlers were not the first to undertake such a project. Bowdler's commitment to not augmenting or adding to Shakespeare's text, instead only removing sensitive material, was in contrast with the practice of earlier editors. Nahum Tate as Poet Laureate had rewritten the tragedy of "King Lear" with a happy ending; In 1807, Charles Lamb and Mary Lamb published "Tales from Shakespeare" for children with synopses of 20 of the plays, but seldom quoted the original text. Though "The Family Shakespeare" was considered a negative example of censorship by the literary establishment and its commitment to the "authentic" Shakespeare, the Bowdlers' expurgated editions made it more acceptable to teach Shakespeare to wider and younger audiences. As said by the poet Algernon Charles Swinburne, "More nauseous and more foolish cant was never chattered than that which would deride the memory or depreciate the merits of Bowdler. No man ever did better service to Shakespeare than the man who made it possible to put him into the hands of intelligent and imaginative children".

Changes.

Some examples of alterations made by Bowdler's edition:  Prominent modern literary figures such as Michiko Kakutani (in the New York Times) and William Safire (in his book, "How Not to Write") have accused Bowdler of changing Lady Macbeth's famous "Out, damned spot!" line in "Macbeth" to "Out, crimson spot!" But Bowdler did not do that. Thomas Bulfinch and Stephen Bulfinch did, in their 1865 edition of Shakespeare's works.

Thomas Bowdler, LRCP, FRS (; 11 July 1754 – 24 February 1825) was an English doctor best known for publishing "The Family Shakespeare", an expurgated edition of William Shakespeare's plays. The work, edited by his sister Henrietta Maria Bowdler, was intended to provide a version of Shakespeare that was more appropriate than the original for 19th-century women and children. Bowdler also published several other works, some reflecting his interest in and knowledge of continental Europe. Bowdler's last work was an expurgated version of Edward Gibbon's "Decline and Fall of the Roman Empire", published posthumously in 1826 under the supervision of his nephew and biographer, Thomas Bowdler the Younger.

托马斯·鲍德勒,伦敦皇家内科医学院成员,英国皇家学会会员(Thomas Bowdler 1754年7月11日–1825年2月24日),是一名凭借出版《家庭版莎士比亚集》,即删节版的莎士比亚集的工作而闻名的英国内科医生。这部由其妹亨利塔·玛丽亚·鲍德勒协助编辑的作品,旨在提供一个较原版更为适合十九世纪的妇女儿童阅读的莎士比亚集的版本。


Components.

There were several major API components to Gears:

Support.

Several web applications from a variety of companies used Gears at some point, including Google (Gmail, YouTube, Docs, Reader, Picasa for mobile, Calendar, Wave), MySpace (Mail Search), Zoho Office Suite, Remember The Milk, and Buxfer. WordPress 2.6 added support for Gears, to speed up the administrative interface and reduce server hits. However, after Google announced in February 2010 that there would be no further development of Gears (see End of life section), several of these applications discontinued their support for Gears, including Google Reader and WordPress  Gears could be enabled on sites where it was otherwise unsupported, by using a Greasemonkey user script that one of the Gears engineers created.  Gears was supported on Internet Explorer 6 and Internet Explorer 8 on Windows XP, Vista, and Seven, Internet Explorer Mobile 4.01 and later on Windows Mobile, Safari 3.1.1 and later on Mac OS X 10.4 and later (though not with Safari 4 on Mac OS X 10.6), and Firefox 1.5 and later on multiple platforms. There was only limited 64 bit support from third parties.  Gears did not support attachment files with sizes greater than 2 GB under Mac OS X Leopard or Snow Leopard due to a bug in the Blob handling code.  On May 29, 2008, Opera Software ASA announced that Opera Mobile 9.5 would support Gears. The technology preview release of the browser was published on February 20, 2009. It was available for touch-screen devices on Windows Mobile 5 & 6 only. Gears was not built into browsers other than Google Chrome and had to be downloaded separately.  The Ruby on Rails framework supported interfaces to Gears without needing to understand the Google Gears API.

End of life.

In late November 2009, numerous online news sources reported that Google was going to migrate to Web Storage rather than use Gears in the future. A Google spokesman later clarified that Google would, however, continue to support Gears so as not to break sites using it. On February 19, 2010, the Gears team at Google announced that the development of Google Gears had stopped, as they are working on bringing all of the Gears capabilities into web standards like HTML5. Although development of new features had ceased, Google was planning to continue supporting Gears until they have developed a "simple, comprehensive" method for users' data to be migrated to HTML5 features. On 22 November 2011, Google announced that on 1 December 2011, Gears support would be removed from Gmail and Google Calendar. Gears was removed from Google Chrome on June 7, 2011.

Gears, formerly Google Gears, is discontinued utility software offered by Google that aimed to facilitate creating more powerful web apps by adding offline storage and other additional features to web browsers. Released under the BSD license, Gears is free and open-source. Gears was conceived at a time when a comparable alternative was not available. However, Gears was discontinued in favor of the standardized HTML5 methods that eventually became prevalent.

Gears,原称Google Gears,是一款Google开发的软件,让使用者可以离线浏览。这套软件透过以浏览器扩展的方式添加JavaScript API使得浏览器的脚本能够访问本地的SQLite缓存数据库。所以网页是透过暂存区取得的,而不是从实际的网络上取得。而且,Web相关的程序可以周期性的透过Gears将本地暂存的资料与网络上的资料做同步。如果网络暂时无法使用,这个同步过程将会延后,直到网络恢复为止。因此,Gears的Web相关应用并不是即时的。


History.

In 1990, the Times Mirror Company founded the Times Mirror Center for the People & the Press as a research project, tasked with conducting polls on politics and policy. Andrew Kohut became its director in 1993, and The Pew Charitable Trusts became its primary sponsor in 1996, when it was renamed the Pew Research Center for the People & the Press.  In 2004, the trust established the Pew Research Center in Washington, D.C. In 2013, Kohut stepped down as president and became founding director, and Alan Murray became the second president of the center. In October 2014, Michael Dimock, a 14-year veteran of the Pew Research Center, was named president.

Funding.

The Pew Research Center is a nonprofit, tax-exempt 501(c)(3) organization and a subsidiary of The Pew Charitable Trusts, its primary funder. For its studies focusing on demographics of religions in the world, the Pew Research Center has been jointly funded by the Templeton Foundation.

Research areas.

The Center's research is divided into nine areas:

Reports.

Researchers at the Pew Research Center annually comb through publicly available sources of information and publications. Each annual report looks at events that took place about 18 months to two years before its publication.  The Pew Research Center released its 10th annual report on Global Restrictions on Religion as part of the Pew-Templeton Global Religious Futures project, funded by The Pew Charitable Trusts and the John Templeton Foundation. While the previous reports focused on year-over-year change, this report provides a broader look at the trend in particular regions and in 198 countries. The report documents how government restrictions on religion and social hostilities involving religion have changed and increased, from 2007 to 2017. It said 52 governments impose high levels of restrictions on religion, up from 40 in 2007, while 56 countries experienced the highest levels of social hostilities involving religion, up from 38 in 2007. According to the report, laws and policies restricting religious freedom and government favoritism of religious groups are the two types of restrictions that have been the most prevalent. The trends suggest that religious restrictions have been rising around the world but not so evenly across all geographic regions or all kinds of restrictions.

The Pew Research Center is a nonpartisan American think tank (referring to itself as a "fact tank") based in Washington, D.C. It provides information on social issues, public opinion, and demographic trends shaping the United States and the world. It also conducts public opinion polling, demographic research, media content analysis, and other empirical social science research. The Pew Research Center does not take policy positions, and is a subsidiary of The Pew Charitable Trusts.

皮尤研究中心(Pew Research Center)是美国的一间民调机构和智库机构。


Definition and overview.

A "Conway chain" is defined as follows:  Any chain represents an integer, according to the five (technically four) rules below. Two chains are said to be equivalent if they represent the same integer.  If formula_4, formula_5, and formula_6 are positive integers, and formula_7 is a subchain, then:  Note that the fourth rule can be replaced by repeatedly applying two rules to avoid the ellipses:

Interpretation.

One must be careful to treat an arrow chain "as a whole". Arrow chains do not describe the iterated application of a binary operator. Whereas chains of other infixed symbols (e.g. 3 + 4 + 5 + 6 + 7) can often be considered in fragments (e.g. (3 + 4) + 5 + (6 + 7)) without a change of meaning (see associativity), or at least can be evaluated step by step in a prescribed order, e.g. 3 from right to left, that is not so with Conway's arrow chains.  For example:  The fourth rule is the core: A chain of 4 or more elements ending with 2 or higher becomes a chain of the same length with a (usually vastly) increased penultimate element. But its "ultimate" element is decremented, eventually permitting the second rule to shorten the chain. After, to paraphrase Knuth, "much detail", the chain is reduced to three elements and the third rule terminates the recursion.

Examples.

Examples get quite complicated quickly. Here are some small examples:  formula_45  formula_47  formula_50  formula_58  formula_61  formula_70  formula_75

Systematic examples.

The simplest cases with four terms (containing no integers less than 2) are:  We can see a pattern here. If, for any chain formula_7, we let formula_94 then formula_95 (see functional powers).  Applying this with formula_96, then formula_97 and formula_98  Thus, for example, formula_99.  Moving on:  Again we can generalize. When we write formula_105 we have formula_106, that is, formula_107. In the case above, formula_108 and formula_109, so formula_110

Ackermann function.

The Ackermann function may be expressed using Conway chained arrow notation:  hence

Graham's number.

Graham's number formula_120 itself cannot be expressed concisely in Conway chained arrow notation, but it is bounded by the following:  formula_121  Proof: We first define the intermediate function formula_122, which can be used to define Graham's number as formula_123. (The superscript 64 denotes a functional power.)  By applying rule 2 and rule 4 backwards, we simplify:  formula_124 formula_129  formula_130 formula_133  formula_134 formula_141  Since "f" is strictly increasing, which is the given inequality.  With chained arrows, it is very easy to specify a number much greater than formula_143, for example, formula_144.  formula_145 formula_149 which is much greater than Graham's number, because the number formula_150 formula_151 is much greater than formula_152.

CG function.

Conway and Guy created a simple, single-argument function that diagonalizes over the entire notation, defined as:  formula_153  meaning the sequence is:  formula_154  formula_155  formula_156  formula_157  formula_158  This function, as one might expect, grows extraordinarily fast.

Extension by Peter Hurford.

Peter Hurford, a web developer and statistician, has defined an extension to this notation:  formula_159  formula_160  All normal rules are unchanged otherwise.  formula_161 is already equal to the aforementioned formula_162, and the function formula_163 is much faster growing than Conway and Guy's formula_164.  Note that expressions like formula_165 are illegal if formula_166 and formula_167 are different numbers; one chain must only have one type of right-arrow.  However, if we modify this slightly such that:  formula_168  then not only does formula_165 become legal, but the notation as a whole becomes much stronger.

Conway chained arrow notation, created by mathematician John Horton Conway, is a means of expressing certain extremely large numbers. It is simply a finite sequence of positive integers separated by rightward arrows, e.g. formula_1.

康提(僧伽罗语:මහ නුවර ;泰米尔语:கண்டி ;英语:Kandy),斯里兰卡中部城市,中央省省会。2001年人口110049人。1592年起为斯里兰卡首都和佛教圣城。1815年被英国征服。此后至今,康提不再是斯里兰卡的首都,但是保持了佛教朝圣地的地位,其名胜包括佛牙寺(Sri Dalada Maligawa)等。1988年康提被联合国教科文组织列为世界遗产地。


Bacterial diversity.

Molecular ecological techniques used to study "in situ" questions of bacterial diversity. many microorganisms are not easily obtainable as cultured strains in the laboratory, which would allow for identification and characterization. It also stems from the development of PCR technique, which allows for the rapid amplification of genetic material.  The amplification of DNA from environmental samples using general or group-specific primers leads to a mix of genetic material, requiring sorting before sequencing and identification. The classic technique to achieve this is through cloning, which involves incorporating the amplified DNA fragments into bacterial plasmids. Techniques such as temperature gradient gel electrophoresis, allow for a faster result. More recently, the advent of relatively low-cost, next-generation DNA sequencing technologies, such as 454 and Illumina platforms, has allowed exploration of bacterial ecology concerning continental-scale environmental gradients such as pH that was not feasible with traditional technology.

Fungal diversity.

Exploration of fungal diversity "in situ" has also benefited from next-generation DNA sequencing technologies. The use of high-throughput sequencing techniques has been widely adopted by the fungal ecology community since the first publication of their use in the field in 2009. Similar to the exploration of bacterial diversity, these techniques have allowed high-resolution studies of fundamental questions in fungal ecology such as phylogeography, fungal diversity in forest soils, stratification of fungal communities in soil horizons, and fungal succession on decomposing plant litter.  The majority of fungal ecology research leveraging next-generation sequencing approaches involves sequencing of PCR amplicons of conserved regions of DNA (i.e. marker genes) to identify and describe the distribution of taxonomic groups in the fungal community in question, though more recent research has focused on sequencing functional gene amplicons (e.g. Baldrian et al. 2012). The locus of choice for a description of the taxonomic structure of fungal communities has traditionally been the internal transcribed spacer (ITS) region of ribosomal RNA genes due to its utility in identifying fungi to genus or species taxonomic levels, and its high representation in public sequence databases. A second widely used locus (e.g. Amend et al. 2010, Weber et al. 2013), the D1-D3 region of 28S ribosomal RNA genes, may not allow the low taxonomic level classification of the ITS, but demonstrates superior performance in sequence alignment and phylogenetics. Also, the D1-D3 region may be a better candidate for sequencing with Illumina sequencing technologies. Porras-Alfaro et al. showed that the accuracy of classification of either ITS or D1-D3 region sequences was largely based on the sequence composition and quality of databases used for comparison, and poor-quality sequences and sequence misidentification in public databases is a major concern. The construction of sequence databases that have broad representation across fungi, and that are curated by taxonomic experts is a critical next step.  Next-generation sequencing technologies generate large amounts of data, and analysis of fungal marker-gene data is an active area of research. Two primary areas of concern are methods for clustering sequences into operational taxonomic units by sequence similarity and quality control of sequence data. Currently, there is no consensus on preferred methods for clustering, and clustering and sequence processing methods can significantly affect results, especially for the variable-length ITS region. In addition, fungal species vary in intra-specific sequence similarity of the ITS region. Recent research has been devoted to the development of flexible clustering protocols that allow sequence similarity thresholds to vary by taxonomic groups, which are supported by well-annotated sequences in public sequence databases.

Extra-pair fertilizations.

In recent years, molecular data and analyses have been able to supplement traditional approaches of behavioral ecology, the study of animal behavior in relation to its ecology and evolutionary history. One behavior that molecular data has helped scientists better understand is extra-pair fertilizations (EPFs), also known as extra-pair copulations (EPCs). These are mating events that occur outside of a social bond, like monogamy and are hard to observe. Molecular data has been key to understanding the prevalence of and the individuals participating in EPFs.  While most bird species are socially monogamous, molecular data has revealed that less than 25% of these species are genetically monogamous. EPFs complicate matters, especially for male individuals, because it does not make sense for an individual to care for offspring that are not their own. Studies have found that males will adjust their parental care in response to changes in their paternity. Other studies have shown that in socially monogamous species, some individuals will employ an alternative strategy to be reproductively successful since a social bond does not always equal reproductive success.  It appears that EPFs in some species is driven by the good genes hypothesis, In red-back shrikes ("Lanius collurio") extra-pair males had significantly longer tarsi than within-pair males, and all of the extra-pair offspring were males, supporting the prediction that females will bias their clutch towards males when they mate with an "attractive" male. In house wrens ("Troglodytes aedon)", extra-pair offspring were also found to be male-biased compared to within-offspring.  Without molecular ecology, identifying individuals that participate in EPFs and the offspring that result from EPFs would be impossible.

Isolation by distance.

Isolation by distance (IBD), like reproductive isolation, is the effect of physical barriers to populations that limit migration and lower gene flow. The shorter the distance between populations the more likely individuals are to disperse and mate and thus, increase gene flow. The use of molecular data, specifically allele frequencies of individuals among populations in relation to their geographic distance help to explain concepts such as, sex-biased dispersal, speciation, and landscape genetics.  The Mantel test is an assessment that compares genetic distance with geographic distance and is most appropriate because it doesn't assume that the comparisons are independent of each other. There are three main factors that influence the chances of finding a correlation of IBD, which include sample size, metabolism, and taxa. For example, based on the meta-analysis, ectotherms are more likely than endotherms to display greater IBD.

Metapopulation theory.

Metapopulation theory dictates that a metapopulation consists of spatially distinct populations that interact with one another on some level and move through a cycle of extinctions and recolonizations (i.e. through dispersal). The most common metapopulation model is the extinction-recolonization model which explains systems in which spatially distinct populations undergo stochastic changes in population sizes which may lead to extinction at the population level. Once this has occurred, dispersing individuals from other populations will immigrate and "rescue" the population at that site. Other metapopulation models include the source-sink model (island-mainland model) where one (or multiple) large central population(s) produces disperses to smaller satellite populations that have a population growth rate of less than one and could not persist without the influx from the main population.  Metapopulation structure and the repeated extinctions and recolonizations can significantly affect a population's genetic structure. Recolonization by a few dispersers leads to population bottlenecks which will reduce the effective population size (Ne), accelerate genetic drift, and deplete genetic variation. However, dispersal between populations in the metapopulation can reverse or halt these processes over the long term. Therefore, in order for individual sub-populations to remain healthy, they must either have a large population size or have a relatively high rate of dispersal with other subpopulations. Molecular ecology focuses on using tests to determine the rates of dispersal between populations and can use molecular clocks to determine when historic bottlenecks occurred. As habitat becomes more fragmented, dispersal between populations will become increasingly rare. Therefore, subpopulations that may have historically been preserved by a metapopulation structure may start to decline. Using mitochondrial or nuclear markers to monitor dispersal coupled with population Fst values and allelic richness can provide insight into how well a population is performing and how it will perform into the future.

Molecular clock hypothesis.

The molecular clock hypothesis states that DNA sequences roughly evolve at the same rate and because of this the dissimilarity between two sequences can be used to tell how long ago they diverged from one another. The first step in using a molecular clock is it must be calibrated based on the approximate time the two lineages studied diverged. The sources usually used to calibrate the molecular clocks are fossils or known geological events in the past. After calibrating the clock the next step is to calculate divergence time by dividing the estimated time since the sequences diverged by the amount of sequence divergence. The resulting number is the estimated rate at which molecular evolution is occurring. The most widely cited molecular clock is a ‘universal’ mtDNA clock of approximately two percent sequence divergence every million years. Although referred to as a universal clock, this idea of the "universal" clock is not possible considering rates of evolution differ within DNA regions. Another drawback to using molecular clocks is that they ideally need to be calibrated from an independent source of data other than the molecular data. This poses a problem for taxa that don't fossilize/preserve easily, making it almost impossible to calibrate their molecular clock. Despite these inconveniences, the molecular clock hypothesis is still used today. The molecular clock has been successful in dating events happening up to 65 million years ago.

Mate choice hypotheses.

The concept of mate choice explains how organisms select their mates based on two main methods; The Good Genes Hypothesis and Genetic Compatibility. The Good Genes Hypothesis, also referred to as the sexy son hypothesis, suggests that the females will choose a male that produce an offspring that will have increased fitness advantages and genetic viability. Therefore, the mates that are more 'attractive" are more likely to be chosen for mating and pass on their genes to the next generation. In species which exhibit polyandry the females will search out for the most suitable males and re-mate until they have found the best sperm to fertilize their eggs. Genetic compatibility is where mates are choosing their partner based on the compatibility of their genotypes. The mate which is doing the selecting must know their own genotype as well as the genotypes of potential mates in order to select the appropriate partner. Genetic compatibility in most instances is limited to specific traits, such as the major histocompatibility complex in mammals, because of complex genetic interactions. This behavior is potentially seen in humans. A study looking at women's choice in men based on body odors concluded that the scent of the odors were influenced by the MHC and that they influence mate choice in human populations.

Sex-biased dispersal.

Sex-biased dispersal, or the tendency of one sex to disperse between populations more frequently than the other, is a common behavior studied by researchers. Three major hypotheses currently exist to help explain sex-biased dispersal. The resource-competition hypothesis infers that the more philopatric sex (the sex more likely to remain at its natal grounds) benefits during reproduction simply by having familiarity with natal ground resources. A second proposal for sex-biased dispersal is the local mate competition hypothesis, which introduces the idea that individuals encounter less mate competition with relatives the farther from their natal grounds they disperse. And the inbreeding avoidance hypothesis suggests individuals disperse to decrease inbreeding.  Studying these hypotheses can be arduous since it is nearly impossible to keep track of every individual and their whereabouts within and between populations. To combat this time-consuming method, scientists have recruited several molecular ecology techniques in order to study sex-biased dispersal. One method is the comparison of differences between nuclear and mitochondrial markers among populations. Markers showing higher levels of differentiation indicate the more philopatric sex; that is, the more a sex remains at natal grounds, the more their markers will take on a unique I.D, due to lack of gene flow with respect to that marker. Researchers can also quantify male-male and female-female pair relatedness within populations to understand which sex is more likely to disperse. Pairs with values consistently lower in one sex indicate the dispersing sex. This is because there is more gene flow in the dispersing sex and their markers are less similar than individuals of the same sex in the same population, which produces a low relatedness value. FST values are also used to understand dispersing behaviors by calculating an FST value for each sex. The sex that disperses more displays a lower FST value, which measures levels of inbreeding between the subpopulation and the total population. Additionally, assignment tests can be utilized to quantify the number of individuals of a certain sex dispersing to other populations. A more mathematical approach to quantifying sex-biased dispersal on the molecular level is the use of spatial autocorrelation. This correlation analyzes the relationship between geographic distance and spatial distance. A correlation coefficient, or r value, is calculated and the plot of r against distance provides an indication of individuals more related to or less related to one another than expected.

Quantitative trait loci.

A quantitative trait locus (QTL) refers to a suite of genes that controls a quantitative trait. A quantitative trait is one that is influenced by several different genes as opposed to just one or two. QTLs are analyzed using Qst. Qst looks at the relatedness of the traits in focus. In the case of QTLs, clines are analyzed by Qst. A cline (biology) is a change in allele frequency across a geographical distance. This change in allele frequency causes a series of intermediate varying phenotypes that when associated with certain environmental conditions can indicate selection. This selection causes local adaptation, but high gene flow is still expected to be present along the cline.  For example, barn owls in Europe exhibit a cline in reference to their plumage coloration. Their feathers range in coloration from white to reddish-brown across the geological range of the southwest to the northeast. This study sought to find if this phenotypic variation was due to selection by calculating the Qst values across the owl populations. Because high gene flow was still anticipated along this cline, selection was only expected to act upon the QTLs that incur locally adaptive phenotypic traits. This can be determined by comparing the Qst values to Fst (fixation index) values. If both of these values are similar and Fst is based on neutral markers then it can be assumed that the QTLs were based on neutral markers (markers not under selection or locally adapted) as well. However, in the case of the barn owls the Qst value was much higher than the Fst value. This means that high gene flow was present allowing the neutral markers to be similar, indicated by the low Fst value. But, local adaptation due to selection was present as well, in the form of varying plumage coloration since the Qst value was high, indicating differences in these non-neutral loci. In other words, this cline of plumage coloration has some sort of adaptive value to the birds.

Fixation indices.

Fixation indices are used when determining the level of genetic differentiation between sub-populations within a total population. F is the script used to represent this index when using the formula: In this equation, H represents the expected heterozygosity of the total population and H is the expected heterozygosity of a sub-populations. Both measures of heterozygosity are measured at one loci. In the equation, heterozygosity values expected from the total population are compared to observed heterozygosity values of the sub-populations within this total population. Larger F values imply that the level of genetic differentiation between sub-populations within a total population is more significant. The level of differentiation is the result of a balance between gene flow amongst sub-populations (decreasing differentiation) and genetic drift within these sub-populations (increasing differentiation); however, some molecular ecologists note that it cannot be assumed that these factors are at equilibrium. F can also be viewed as a way of comparing the amount of inbreeding within sub-populations to the amount of inbreeding for the total population and is sometimes referred to as an inbreeding coefficient. In these cases, higher F values typically imply higher amounts of inbreeding within the sub-populations. Other factors such as selection pressures may also affect F values.  F values are accompanied by several analog equations (F, G, etc.). These additional measures are interpreted in a similar manner to F values; however, they are adjusted to accompany other factors that F may not, such as accounting for multiple loci.

Inbreeding depression.

Inbreeding depression is the reduced fitness and survival of offspring from closely related parents. Inbreeding is commonly seen in small populations because of the greater chance of mating with a relative due to limited mate choice. Inbreeding, especially in small populations, is more likely to result in higher rates of genetic drift, which leads to higher rates of homozygosity at all loci in the population and decreased heterozygosity. The rate of inbreeding is based on decreased heterozygosity. In other words, the rate at which heterozygosity is lost from a population due to genetic drift is equal to the rate of accumulating inbreeding in a population. In the absence of migration, inbreeding will accumulate at a rate that is inversely proportional to the size of the population.  There are two ways in which inbreeding depression can occur. The first of these is through dominance, where beneficial alleles are usually dominant and harmful alleles are usually recessive. The increased homozygosity resulting from inbreeding means that harmful alleles are more likely to be expressed as homozygotes, and the deleterious effects cannot be masked by the beneficial dominant allele. The second method through which inbreeding depression occurs is through overdominance, or heterozygote advantage. Individuals that are heterozygous at a particular locus have a higher fitness than homozygotes at that locus. Inbreeding leads to decreased heterozygosity, and therefore decreased fitness.  Deleterious alleles can be scrubbed by natural selection from inbred populations through genetic purging. As homozygosity increases, less fit individuals will be selected against and thus those harmful alleles will be lost from the population.

Outbreeding depression.

Outbreeding depression is the reduced biological fitness in the offspring of distantly related parents. The decline in fitness due to outbreeding is attributed to a breakup of coadapted gene complexes or favorable epistatic relationships. Unlike inbreeding depression, outbreeding depression emphasizes interactions between loci rather than within them. Inbreeding and outbreeding depression can occur at the same time. Risks of outbreeding depression increase with increased distance between populations. The risk of outbreeding depression during genetic rescue often limits the ability to increase a small or fragmented gene pool's genetic diversity. The spawn of an intermediate of two or more adapted traits can render the adaptation less effective than either of the parental adaptations. Three main mechanisms influence outbreeding depression; genetic drift, population bottlenecking, differentiation of adaptations, and set chromosomal dissimilarities resulting in sterile offspring. If outbreeding is limited and the population is large enough, selective pressure acting on each generation may be able to restore fitness. However, the population is likely to experience a multi-generational decline of overall fitness as selection for traits takes multiple generations. Selection acts on outbred generations using increased diversity to adapt to the environment. This may result in greater fitness among offspring than the original parental type.

Conservation units.

Conservation units are classifications often used in conservation biology, conservation genetics, and molecular ecology in order to separate and group different species or populations based on genetic variance and significance for protection. Two of the most common types of conservation units are: Conservation units are often identified using both neutral and non-neutral genetic markers, with each having its own advantages. Using neutral markers during unit identification can provide unbiased assumptions of genetic drift and time since reproductive isolation within and among species and populations, while using non-neutral markers can provide more accurate estimations of adaptive evolutionary divergence, which can help determine the potential for a conservation unit to adapt within a certain habitat.  Because of conservation units, populations and species that have high or differing levels of genetic variation are can be distinguished in order to manage each individually, which can ultimately differ based on a number of factors. In one instance, Atlantic salmon located within the Bay of Fundy were given evolutionary significance based on the differences in genetic sequences found among different populations. This detection of evolutionary significance can allow each population of salmon to receive customized conservation and protection based on their adaptive uniqueness in response to geographic location.

Phylogenies and community Ecology.

Phylogenies are the evolutionary history of an organism, also known as phylogeography. A phylogenetic tree is a tree that shows evolutionary relationships between different species based on similarities/differences among genetic or physical traits. Community ecology is based on knowledge of evolutionary relationships among coexisting species. Phylogenies embrace aspects of both time (evolutionary relationships) and space (geographic distribution). Typically phylogeny trees include tips, which represent groups of descendent species, and nodes, which represent the common ancestors of those descendants. If two descendants split from the same node, they are called sister groups. They also may include an outgroup, a species outside of the group of interest. The trees depict clades, which is a group of organisms that include an ancestor and all descendants of that ancestor. The maximum parsimony tree is the simplest tree that has the minimum number of steps possible.  Phylogenies confer important historical processes that shape current distributions of genes and species. When two species become isolated from each other they retain some of the same ancestral alleles also known as allele sharing. Alleles can be shared because of lineage sorting and hybridization. Lineage sorting is driven by genetic drift and must occur before alleles become species specific. Some of these alleles over time will simply be lost, or they may proliferate. Hybridization leads to introgression of alleles from one species to another.  Community ecology emerged from natural history and population biology. Not only does it include the study of the interactions between species, but it also focuses on ecological concepts such as mutualism, predation, and competition within communities. It is used to explicate properties such as diversity, dominance, and composition of a community. There are three primary approaches to integrating phylogenetic information into studies of community organizations. The first approach focuses on examining the phylogenetic structure of community assemblages. The second approach focuses on exploring the phylogenetic basis of community niche structures. The final way zones in on adding a community context to studies of trait evolution and biogeography.

Species concepts.

Species concepts are the subject of debate in the field of molecular ecology. Since the beginning of taxonomy, scientists have wanted to standardize and perfect the way species are defined. There are many species concepts that dictate how ecologists determine a good species. The most commonly used concept is the biological species concept which defines a species as groups of actually or potentially interbreeding natural populations, which are reproductively isolated from other such groups (Mayr, 1942). This concept is not always useful, particularly when it comes to hybrids. Other species concepts include phylogenetic species concept which describes a species as the smallest identifiable monophyletic group of organisms within which there is a parental pattern of ancestry and descent. This concept defines species on the identifiable. It would also suggest that until two identifiable groups actually produce offspring, they remain separate species. In 1999, John Avise and Glenn Johns suggested a standardized method for defining species based on past speciation and measuring biological classifications as time dependent. Their method used temporal banding to make genus, family and order based on how many tens of millions of years ago the speciation event that resulted in each species took place.

Landscape genetics.

Landscape genetics is a rapidly emerging interdisciplinary field within molecular ecology. Landscape genetics relates genetics to landscape characteristics, such as land-cover use (forests, agriculture, roads, etc.), presence of barriers, and corridors, rivers, elevation, etc. Landscape genetics answers how landscape affects dispersal and gene flow.  Barriers are any landscape features that prevents dispersal. Barriers for terrestrial species can include mountains, rivers, roads, and unsuitable terrain, such as agriculture fields. Barriers for aquatic species can include islands or dams. Barriers are species specific; for example a river is a barrier to a field mouse, while a hawk can fly over a river. Corridors are areas over which dispersal is possible. Corridors are stretches of suitable habitat and can also be man-made, such as overpasses over roads and fish ladders on dams.  Geographic data used for landscape genetics can include data collected by radars in planes, land satellite data, marine data collected by NOAA, as well as any other ecological data. In landscape genetics researchers often use different analyses to attempt to determine the best way for a species to travel from point A to point B. Least cost path analysis uses geographic data to determine the most efficient path from one point to another. Circuit scape analysis predicts all the possible paths and the probability of each path's use between point A and point B. These analyses are used to determine the route a dispersing individual is likely to travel.  Landscape genetics is becoming an increasingly important tool in wildlife conservation efforts. It is being used to determine how habitat loss and fragmentation affects the movement of species. It is also used to determine which species need to be managed and whether to manage subpopulations the same or differently according to their gene flow.

Molecular ecology is a field of evolutionary biology that is concerned with applying molecular population genetics, molecular phylogenetics, and more recently genomics to traditional ecological questions (e.g., species diagnosis, conservation and assessment of biodiversity, species-area relationships, and many questions in behavioral ecology). It is virtually synonymous with the field of "Ecological Genetics" as pioneered by Theodosius Dobzhansky, E. B. Ford, Godfrey M. Hewitt, and others. These fields are united in their attempt to study genetic-based questions "out in the field" as opposed to the laboratory. Molecular ecology is related to the field of conservation genetics.

分子生态学是利用进化生物学理论,采用分子生物学和基因组学的实验方法和技术手段、统计学和数学的分析方法,通过计算机科学的技术和算法,旁及地学、古气候学等, 研究物种和种群的遗传变异及表观遗传变异、遗传谱系, 探讨生物多样性演化、生物地理演化、物种分化、生态适应等的生态学和进化生物学机制。


Theory.

Within the assumptions embodied in thin airfoil theory, the aerodynamic center is located at the quarter-chord (25% chord position) on a symmetric airfoil while it is close but not exactly equal to the quarter-chord point on a cambered airfoil.  From thin airfoil theory:  Differentiating with respect to angle of attack  For symmetrical airfoils formula_12, so the aerodynamic center is at 25% of chord. But for cambered airfoils the aerodynamic center can be slightly less than 25% of the chord from the leading edge, which depends on the slope of the moment coefficient, formula_13. These results obtained are calculated using the thin airfoil theory so the use of the results are warranted only when the assumptions of thin airfoil theory are realistic. In precision experimentation with real airfoils and advanced analysis, the aerodynamic center is observed to change location slightly as angle of attack varies. In most literature however the aerodynamic center is assumed to be fixed at the 25% chord position.

Role of aerodynamic center in aircraft stability.

For longitudinal static stability: formula_14 and formula_15  For directional static stability: formula_16 and formula_17  Where:  For a force acting away from the aerodynamic center, which is away from the reference point:  Which for small angles formula_21 and formula_22, formula_23, formula_24, formula_25 simplifies to:  General Case: From the definition of the AC it follows that  The Static Margin can then be used to quantify the AC:  where:  SM = Static Margin

The torques or moments acting on an airfoil moving through a fluid can be accounted for by the net lift and net drag applied at some point on the airfoil, and a separate net pitching moment about that point whose magnitude varies with the choice of where the lift is chosen to be applied. The Aerodynamic center is the point at which the pitching moment coefficient for the airfoil does not vary with lift coefficient (i.e. angle of attack), making analysis simpler.

空气动力中心(英语:aerodynamic center,简称英语:AC)在空气动力学中是指翼型上的一个定点,绕该点的俯仰力矩不随迎角的改变而变化,即 其中formula_2为该点的俯仰力矩系数,formula_3为迎角。根据薄翼理论,空气动力中心位于翼型的四分之一弦长处。


Biography.

Tukulti-Ninurta I succeeded Shalmaneser I, his father, as king and won a major victory against the Hittite Empire at the Battle of Nihriya in the first half of his reign, appropriating Hittite territory in Asia Minor and the Levant. Tukulti-Ninurta I retained Assyrian control of Urartu, and later defeated Kashtiliash IV, the Kassite king of Babylonia, and captured the rival city of Babylon to ensure full Assyrian supremacy over Mesopotamia. He set himself up as king of Babylon, thus becoming the first native Mesopotamian to rule there, its previous kings having all been non-native Amorites or Kassites. He took on the ancient title "King of Sumer and Akkad" first used by Sargon of Akkad.  Tukulti-Ninurta had petitioned the god Shamash before beginning his counter offensive. Kashtiliash IV was captured, single-handed by Tukulti-Ninurta according to his account, who "trod with my feet upon his lordly neck as though it were a footstool" and deported him ignominiously in chains to Assyria. The victorious Assyrian demolished the walls of Babylon, massacred many of the inhabitants, pillaged and plundered his way across the city to the Esagila temple, where he made off with the statue of Marduk. After capturing Babylonia, he invaded the Arabian Peninsula, conquering the pre-Arab states of Dilmun and Meluhha. Middle Assyrian texts recovered at ancient Dūr-Katlimmu include a letter from Tukulti-Ninurta to his "sukkal rabi'u", or grand vizier, Ashur-iddin advising him of the approach of his general Shulman-mushabshu escorting the captive Kashtiliash, his wife, and his retinue which incorporated a large number of women, on his way to exile after his defeat. In the process he defeated the Elamites, who had themselves coveted Babylon. He also wrote an epic poem documenting his wars against Babylon and Elam. After a Babylonian revolt, he raided and plundered the temples in Babylon, regarded as an act of sacrilege to all Mesopotamians, including Assyrians. As relations with the priesthood in Ashur began deteriorating, Tukulti-Ninurta built a new capital city; Kar-Tukulti-Ninurta. However, his sons rebelled against him and besieged him in his new city. During the siege, he was murdered. One of them, Ashur-nadin-apli, would succeed him on the throne.  After his death, the Assyrian Empire fell into a brief period of stagnation. The "Tukulti-Ninurta Epic" describes the war between Tukulti-Ninurta I and Kashtiliash IV.  Julian Jaynes identifies this king as the historical origin for Nimrod in the Old Testament.

Tukulti-Ninurta I (meaning: "my trust is in [the warrior god] Ninurta"; reigned 1243–1207 BC) was a king of Assyria during the Middle Assyrian Empire (1366–1050 BC). He is known as the first king to use the title "King of Kings".

图库尔蒂-尼努尔塔一世(英语:Tukulti-Ninurta I)(?-前1208年),中亚述时期的亚述国王(公元前1245年—公元前1208年在位)他在东南征服喀西特人的国王卡什提利亚什四世,在东北征服古代的亚美尼亚,并且一度征服巴比伦尼亚。崇尚祭祀,曾建黎明女神伊西塔神庙。此神庙十分著名,为亚述建筑的典范。并扩建亚述城堡,后又在底格里斯河对岸建新都图库尔蒂-尼努尔塔城。公元前1208年为子所弑,死后亚述持续数年中衰。


Legality of same-sex sexual activity.

Same-sex sexual activity has been legal since 1972. At the same time of legalization, the age of consent became equal regardless of gender and/or sexual orientation, at 16.

Recognition of same-sex relationships.

On 18 November 2004, two MPs from the Socialist Left Party introduced a bill to abolish the existing registered partnership law, and make the marriage law gender-neutral. The move was withdrawn and replaced by a request that the cabinet further investigate the issue. The conservative cabinet of that time did not look into the issue. However, the second Stoltenberg Cabinet announced a common, unified marriage act as part of its foundation document, the Soria Moria statement. A public hearing was opened on 16 May 2007.  On 29 May 2008, the Associated Press reported that two Norwegian opposition parties had come out in favour of the new bill, assuring its passage in the Storting. Prior to this, there were some disagreements with members of the current three-party governing coalition on whether the bill had enough votes to pass.  On 14 March 2008, the Norwegian Government proposed a marriage bill on 14 March 2008 that would give lesbian and gay couples the same rights as heterosexuals, including religious weddings (if the church so chooses), adoption and assisted pregnancies. The first parliamentary hearing was held on 11 June 2008, where the bill was approved by 84 votes to 41. The new legislation amended the definition of civil marriage to make it gender-neutral. Norway's upper legislative chamber ("Lagtinget") passed the bill in a 23–17 vote. The King of Norway granted royal assent thereafter. The law took effect on 1 January 2009.  Prior to the gender-neutral marriage law, a registered partnership law had been in effect since 1993. "Partnerskapsloven", as it was known in Norwegian, granted many marriage rights to same-sex couples, only without calling it marriage. Since 1991, unregistered same-sex cohabitation has been recognized by the state for the granting of limited rights, such as being considered as next of kin for medical decisions, and in the event of wrongful death of one partner the other partner was entitled to compensation.  In 2014, the Church of Norway's National Council voted down a proposal to perform same-sex marriages in the church. In 2015, it reversed course and voted to allow same-sex marriages to take place in its churches. The decision was ratified at the annual conference on 11 April 2016.

Adoption and family planning.

Married and committed same-sex couples are permitted to adopt under Norwegian law. Stepchild adoption has been allowed for registered partners since 2002. Full adoption rights were granted to same-sex couples in 2009. Additionally, lesbian couples have access to artificial insemination. Pursuant to the same-sex marriage law, when a woman who is married to or in a stable co-habiting relationship with another woman becomes pregnant through artificial insemination, the other partner will have all the rights and duties of parenthood "from the moment of conception".

Military status.

Lesbian, gay and bisexual people can serve openly in the Armed Forces. They have had full rights and anti-discrimination protections since 1979. Transgender persons may serve openly as well.

Discrimination protections and hate crime laws.

In 1981, Norway became the first country in the world to enact a law to prevent discrimination against LGBT people by amending Paragraph 349a of its Penal Code, prohibiting discrimination based on sexual orientation in the provision of goods or services and in access to public gatherings. In the same year, Paragraph 135a of the Penal Code was amended to prohibit hate speech on account of sexual orientation. The country has banned discrimination based on sexual orientation in employment since 1998. Norway also has a law prohibiting discrimination based on gender identity and expression since 2013, and is one of the few countries in the world to explicitly protect intersex people from discrimination.  Section 5 of the "Act on the Prohibition of Discrimination on the grounds of Sexual Orientation, Gender Identity and Gender Expression" (), enacted in 2013, states as follows:

Bias-motivated violence and speech.

According to a 2013 survey entitled "Sexual orientation and living conditions" ("Seksuell orientering og levekår)" from the University of Bergen, nine out of ten LGBT respondents reported not being exposed to discrimination or harassment at the workplace. In addition, only a small minority stated they had been physically assaulted, and suicide among LGBT people has significantly decreased since the 1990s. Nevertheless, homosexual boys reported a six times higher occurrence of bullying in schools than heterosexual boys.  According to the Oslo Police District, 238 bias-motivated crimes had occurred in Oslo in 2018, of which 20 percent related to LGBT status; the remaining relating to ethnicity (57%), religion (17%), disability (3%) or anti-Semitism (3%).  The Norwegian Institute of Social Research reported in 2019 that LGBT people were more at risk of experiencing hate speech. 15% of LGBT respondents reported having been the target of personal threats, mostly online, compared to 4% among the general population.

Transgender rights.

On 18 March 2016, the Solberg Government introduced a bill to allow legal gender changes without any form of psychiatric or psychological evaluation, diagnosis or any kind of medical intervention, by people aged at least 16. Minors aged between 6 and 16 also may also transition, but require parental consent. The bill was approved by a vote of 79-13 by Parliament on 6 June. It was promulgated on 17 June and took effect on 1 July 2016. One month after the law took effect, 190 people had already applied to change their gender.

Intersex rights.

Intersex infants in Norway may undergo medical interventions to have their sex characteristics altered. Human rights groups increasingly consider these surgeries unnecessary and, they argue, should only be performed if the applicant consents to the operation. A 2019 survey from the Oslo University Hospital showed that two out of three medical professionals were willing to perform such surgeries, and parents were overall supportive of the move. In March 2019, the Norwegian Directorate for Children, Youth and Family Affairs published two reports, recommending postponing such medical interventions on intersex infants until they are able to consent.

Conversion therapy.

In 2000, the Norwegian Psychiatric Association overwhelmingly voted for the position statement that "homosexuality is no disorder or illness, and can therefore not be subject to treatment. A 'treatment' with the only aim of changing sexual orientation from homosexual to heterosexual must be regarded as ethical malpractice, and should have no place in the health system".  As of December 2019, the Storting is considering a ban on conversion therapy.

Health and blood donation.

In Norway, as in many other countries, men who have sex with men (MSM) were previously not allowed to donate blood. In June 2016, the Norwegian Directorate for Health and Social Affairs announced it would make an end to this ban, and implement a 12-month deferral period instead, whereby MSM applicants would be permitted to donate provided they had not had sex in a year. The new 1 year deferral period was implemented on 1 June 2017.  In October 2016, Minister of Health and Care Services Bent Høie made the announcement that the HIV-prevention drug, PrEP, would be offered free of charge as part of Norway's health care system.

Living conditions.

Norway is very gay-friendly. The most open and inclusive community can be found in the capital, Oslo, where many gay-friendly events and venues are located including the Raballder Sports Cup and the Oslo Pride Festival. Other events include the Scandinavian Ski Pride held in Hemsedal, Trondheim Pride held in Trondheim and Bergen Pride ("Regnbuedagene") in Bergen. 45,000 people participated in the 2019 edition of Oslo Pride, and a further 250,000 attended and watched the event, according to the organisers. Several LGBT associations exist throughout the country, including the Association for Gender and Sexuality Diversity ("Foreningen for kjønns- og seksualitetsmangfold"), established in 1950 as the first gay organisation in Norway, Queer Youth ("Skeiv Ungdom"), Gay & Lesbian Health Norway, the Centre for Equality ("Likestillingssenteret") and the Transgender Association ("Forbundet for Transpersoner"), among others. These groups variously offer helplines and counselling to LGBT youth, promote health and HIV prevention and advocate for the legal rights of same-sex couples and transgender individuals. In the far north of Norway, Sápmi Pride is held annually, changing locations between Finland, Sweden and Norway every year. In March 2019, Norway was named the fourth best LGBT-friendly travel destination in the world, tied with Denmark, Iceland and Finland.  The legal situation for same-sex couples is among the best in the world. Norway was the second country, after neighbouring Denmark, to offer registered partnerships to couples with many of the rights of marriage. In 2009, Norway became the sixth country in the world to legalise same-sex marriage, after the Netherlands, Belgium, Spain, Canada and South Africa. Legislation concerning adoption, gender changes for transgender people and anti-discrimination have all been amended in the past decades to include and apply to LGBT people and couples.  In 2015, media reported that there were calls to have a taxi station moved from near the entrance to Oslo's oldest gay pub. Several Muslims claimed that pictures had been taken of them entering the pub by taxi drivers parked at the station; some of these pictures were later distributed widely within Muslim communities.  On 1 September 2016, King Harald V of Norway delivered an impassioned speech in favor of LGBT rights. By 7 September, his speech had received nearly 80,000 likes on Facebook and viewed more than three million times. A part of his speech read as follows:

Public opinion.

Five different polls conducted by Gallup Europe, Sentio, Synovate MMI, Norstat and YouGov in 2003, 2005, 2007, 2008, 2012 and 2013 concluded that 61%, 63%, 66%, 58%, 70% and 78%, respectively, of the Norwegian population supported gender-neutral marriage laws.  In May 2015, PlanetRomeo, an LGBT social network, published its first Gay Happiness Index (GHI). Gay men from over 120 countries were asked about how they feel about society's view on homosexuality, how do they experience the way they are treated by other people and how satisfied are they with their lives. Norway was ranked second, just above Denmark and below Iceland, with a GHI score of 77.

Norway, like most of Scandinavia, is very liberal in regards to lesbian, gay, bisexual, transgender (LGBT) rights. In 1981, Norway became one of the first countries in the world to enact an anti-discrimination law explicitly including sexual orientation. Same-sex marriage, adoption, and assisted insemination treatments for lesbian couples have been legal since 2009. In 2016, Norway became the fourth country in Europe to pass a law allowing the change of legal gender for transgender people solely based on self-determination.

挪威如同多数斯堪地纳维亚国家,社会风气普遍较为自由、开放,亦尊重女同性恋者、男同性恋者、双性恋者与跨性别者(LGBT)的公民权益;它也是全世界第一个在特定地区制定保障同性恋者之反歧视法的国家。


History.

World War I.

The history of Junkers aircraft production begins with the Junkers J 1 mid-wing monoplane (not to be confused with the later, all-metal sesquiplane ground attack aircraft with the "IdFlieg" designation J.I which had a factory designation of J 4). Research for this aircraft began in 1914 and was interrupted by the start of the First World War. The prototype aircraft, named the "Blechesel" (Tin or Sheet-metal Donkey), was completed in very late 1915 after the outbreak of the war. This aircraft is significant in that it was the first flyable aircraft to utilize an all-metal "total structural" design. Contemporary aircraft were built around wooden frames constructed in a rib-and-stringer fashion, reinforced with wires, and covered with a stretched fabric. The J 1 was a semi-monocoque design, using steel ribs and sheeting that formed both the stringers and the skin. At the time aluminium was still fairly expensive and the desirable, newest light duralumin alloy could not be worked in sheet form without damaging flaking occurring, so the J 1 was made of sheet electrical steel. It was quite heavy as a result, which translated into poor climb and maneuverability, yet its clean monoplane layout, which even featured a "belly" radiator installation for its Mercedes D.II inline-six cylinder engine, had very low drag, and the J 1 was one of the fastest aircraft of its day, reaching speeds of 170 km/h, with only a 120 hp engine for power.  Following the J 1, a series of "J-designated" (by the Junkers firm itself) aircraft followed, each advancing the state of the art in terms of strength and weight, but no single design progressed much beyond the prototype stage in terms of production potential. The Junkers J 2 was an extensively "cleaned up" and armed single-seat fighter descendent of the J 1, while the J 3, a never-completed single rotary engined mid-wing monoplane design that only consisted of covered wing panels and a nearly complete fuselage frame, replaced the smooth exterior electrical steel sheeting with corrugated duralumin. "IdFlieg", in charge of aircraft evaluation, was unconvinced of the monoplane layout of these designs, and ordered a sesquiplane design as the J 4. Junkers took this opportunity to produce all the flying surfaces (wings and horizontal stabilizer) of the J 4 aircraft of corrugated duralumin (except for some fabric on the rear fuselage, and the armored steel fuselage "bathtub") in order to lower weight. The J 4 became Junkers' first design to enter production, with orders totalling 283, of which about 184 were delivered to operational units. Since it was the first design from Junkers to serve in the Luftstreitkräfte's ""J"-class" of armored, infantry co-operation aircraft, which also had the Albatros J.I and AEG J.I serving with it in the same capacity, the curious and confusing instance of the Junkers J 4 armored all-metal sesquiplane getting the German military designation "J.I" was one caused solely by the Luftstreitkräfte's choice of designation letter for "all" of its armored, ground forces co-operation aircraft.  Junkers continued to believe in the monoplane layout constructed entirely in metal, and continued the J-series with a number of newer monoplane designs. One of the most successful was the all-duralumin J 7 technology demonstrator aircraft prototype, which went through five major and minor changes in its airframe design during tests throughout 1917 and which was later stretched to form the two-seat J 8. The J 8 was the first cantilever monoplane design, and looked extremely "modern" when compared to contemporary wire-braced biplane designs. The J 8 was put into limited production by the Junkers-Fokker Werke (a collaborative firm founded through strong influence of the German government on October 20, 1917) as the J 10, receiving the "IdFlieg" designation of CL.I, a small number of which saw service on the Eastern Front just before the war ended. Likewise, the single-seat J 7 itself led to the J 9 design, built in small numbers as the Junkers D.I low wing fighter by both the Junkers firm itself (abbreviated "Jco" or "Jko") and the Junkers-Fokker-Werke AG (abbreviated "Jfa") — with the resulting three-letter abbreviation of either firm usually marked on the J-9's landing gear wheel covers.  The corrugated duralumin wing and fuselage "skin" introduced in the J-series became a trademark of Junkers aircraft built in the 1920s and '30s. Development continued during the course of World War I, including a growing (but troublesome) partnership with Fokker, as the "Junkers-Fokker Aktiengesellschaft". Several Junkers designs were licensed to Fokker during this period. The visual similarity of Junkers and Fokker aircraft during the next decade, especially after Reinhold Platz adapted some of the Junkers design concepts, but mostly crafted in wood for the Fokker designs' wing structures instead of the all-metal Junkers construction techniques, is attributable to this early affiliation. The Great War ended with German Navy trials of the model J 11, which was an all-metal floatplane prototype.

Early inter-war period.

In the immediate post-war era, Junkers used their J8 layout as the basis for the F-13, first flown on 25 June 1919 and certified airworthy in July of the same year. This four passenger monoplane was the world's first all-metal airliner. Of note, in addition to significant European sales, some twenty-five of these airplanes were delivered to North American customers under the Junkers-Larsen affiliate and were used primarily as airmail planes.  The Treaty of Versailles signed only days after the F-13 flew, initially forbade any aircraft construction in Germany for several months. After that span of time only the design of civilian aircraft was permitted to Germany. With a partial relocation of the Junkers firm to the Fili western suburb of Moscow, the Junkers firm was able to restart its aircraft manufacturing concern within the borders of the Soviet Union in 1922, the partly revitalized Junkers firm developed a series of progressively larger civil aircraft including the single-engined G.24 and three-engined G.31. Neither aircraft was a commercial success. With the expiration of treaty restrictions in 1926, Junkers introduced the Junkers W33 and Junkers W34 series which did find significant commercial success via large production orders in passenger, freight hauling, and, somewhat later, military configurations. The W-33/W-34 series also set multiple aviation "firsts" including records for flight duration, flight distance, altitude, rocket assisted take-off and inflight refueling between 1926 and 1930.  Junkers' produced a design study in 1924 for a visit to the United States. The study outlined a four-engined 80-passenger plane, incorporating a forward canard wing, as well as a main wing, both of which were fitted above twin pylons. Called the Junkers J.1000 Super Duck passenger seating was to be provided both in the main wing and the hull sections of the craft. This Junkers design, including a scale model, was intended to illustrate an aircraft capable of trans-Atlantic operations of 8 to 10 hours and was completely revolutionary for its day.  It was in 1922 that American engineer William Bushnell Stout, and in 1924 that Soviet engineer Andrei Tupolev each adapted the Junkers corrugated duralumin airframe design technologies for their own initial examples of all-metal aircraft in their respective nations – for Stout, the Stout ST twin-engined naval torpedo bomber prototype aircraft, and for Tupolev, the Tupolev ANT-2 small passenger aircraft, who had the assistance of the Soviet government's TsAGI research center in achieving success with light-weight metal airframes.  The basic principles outlined in this design were later introduced in the Junkers G.38, which was introduced and put into regular service by Deutsche Luft Hansa. At the time of its introduction, this four-engined transport was the largest landplane in the world carrying thirty-four passengers and seven crew members. The G.38 sat some of its passengers in the wing area outboard of the fuselage, the front of which was covered with windows.  Also, in 1932, Junkers joint project with Maybach designed and built an aerodynamic car but found due to the depression that the market for high end luxury cars was saturated.

Financial troubles.

Around 1931 the company suffered from a series of financial difficulties that led to the collapse of the group of companies. The existing shareholders pressured Hugo to leave the company. Hugo, however, was the patent holder on a wide variety of the technologies used in most of the existing Junkers designs, including many of their engines.  A plan was started to solve both problems by "buying out" Hugo's engine patent portfolio and placing it into the hands of a new company, the Junkers Motoren-Patentstelle GmbH, which was eventually formed in November 1932. The new company would then license the technologies back to the various companies, most notably what was then Junkers Motorenbau (one of many "Jumo" companies). However, before Junkers actually transferred his patents to the Patentstelle, the collapse of the Junkers consortium was solved by the sale of the Junkers Thermo Technik GmbH to Robert Bosch, whose company still uses the brand name. Adolf Dethmann, a Communist activist and friend of Hugo, was appointed managing director.

Nazi takeover.

The Nazi party came to power in Germany in 1933, and all German aviation development was shifted away from long-range civil aircraft types. Hugo Junkers himself was forced to transfer all his patents to the Nazis, who doubted that Junkers (a socialist and pacifist) would comply with their plans. Shortly after, his holdings were expropriated and he was placed under house arrest. The company that had pioneered commercial aviation development for at least a decade was relegated to relatively small one- and two-engined military design competitions issued by the "Reichsluftfahrtministerium" (RLM) the "Reich Aviation Ministry". Two exceptions to this were the Ju 52 and the Ju 90.  Ju 52 development had started in 1928 as a single-engined commercial transport and evolved, initially to a two-engined, later into the classic "trimotor" design for which the "Tante Ju" became world-famous. The Ju 52 was a bona fide commercial success, with over 400 airplanes delivered to various airlines around the world prior to the outbreak of World War II, including the countries of: Finland, Sweden, Argentina, Brazil, Uruguay, Ecuador, Peru, Mexico, South Africa, Denmark, Norway, Italy, UK, Belgium, Hungary, Estonia, Greece, Spain, and of course, Germany. As a consequence of its rugged design, Spain and France resumed Ju 52 production after cessation of the Second World War.  With the introduction of the Junkers Ju 86 bomber of 1934, Junkers abandoned the corrugated sheeting of his earlier designs. The basic layout was used in the four-engine Junkers Ju 89 heavy bomber, but this program ended with the death of Walther Wever, and his Ural bomber program along with him. Junkers then adapted the Ju 89 to passenger use, introducing the Junkers Ju 90, one of the first planes specifically designed for scheduled trans-Atlantic flights to the US. Developed in 1937, the aircraft suffered multiple setbacks with crashes of prototypes in 1937 and 1938. Further refinements enabled certification in 1939 and spurred South African Airways to make an initial order for two aircraft fitted with US-built Pratt & Whitney engines. Just as the aircraft was being readied for its first commercial flights, World War II began. With the outbreak of hostilities, all models were requisitioned by the Luftwaffe for military air-transport roles, and later, long-range maritime patrol.

World War II.

Military aircraft production was begun by the company in the 1930s and eventually monopolized all its resources. Perhaps the most notable design was the Junkers Ju 87 "Stuka" dive bomber, one of the Luftwaffe's most effective aerial weapons in the early-war period and continually used for bombing attacks as an integral part of the Blitzkrieg strategy. The Stuka was used both for precision tactical bombing and the strafing of enemy positions, acting as a sort of "airborne artillery" that was able to keep up with the fast-moving tanks and attack defended points long before traditional artillery could be brought into range. Later in the war it was fitted with two large-calibre, "Bordkanone 3,7" 37mm underwing autocannon and employed in a "tank busting" role against Soviet armour. It gained notoriety for its use at both Dunkirk and later Stalingrad, where it caused enormous destruction under Field Marshal Wolfram von Richthofen's VIII Air Corps.  Perhaps even more successful was the Junkers Ju 88, the primary medium bomber of the German forces. It was used in practically every role imaginable; level bomber, shallow-angle dive bomber, night fighter, and bomber destroyer, as well as in anti-shipping raids. A variety of improved versions were also produced over the course of the war, including the Ju 188 and Ju 388 which included numerous features for better performance, but never replaced the Ju 88 outright. A much more formidable aircraft was also planned, the Junkers Ju 288 for the "Bomber B" design competition, which it handily won — but the required high-power engines never worked properly in tests, and as the design was also plagued with insufficiently strong main landing gear, the effort was eventually abandoned.  The Ju 52 was a transport aircraft, roughly equivalent to the Allies' DC-3 Dakota, that was also modified to carry out bombing raids. A total of 4,845 Ju 52 were produced before and during World War II, leading to widespread use delivering men and supplies in support of the German war effort. The Ju 52 had previously seen service in the Spanish Civil War, where it took part in the Condor Legion's destructive raids on Durango and Guernica in 1937 which illustrated to the world—for the first time—the destructive potential and horror of strategic bombing. Unfortunately for its pilots and military passengers, by the outbreak of World War II, the Ju 52 was a thoroughly obsolete military design and unlike many other famous Luftwaffe aircraft, the "Tante Ju" was cumbersome, slow, and therefore vulnerable to attack. This resulted in many losses, namely at Crete and Stalingrad.  The abortive "Amerika Bomber" design competition for a trans-Atlantic range strategic bomber saw the Junkers firm build two prototypes of its six-engined Junkers Ju 390, basically a stretch of the four-engined Ju 290 transport — competing against the trio of Me 264 four-engined prototypes as the only fully airworthy competitors for the contract, which had included designs from Focke-Wulf and Heinkel that were never built, with the competition ended in July 1944 due to the developing need for interceptors to defend the Reich.

Post World War II.

The Junkers company survived the Second World War and the formation of East Germany, and was reconstituted as Junkers GmbH and eventually merged into the MBB consortium (via joint venture Flugzeug-Union-Süd between Heinkel and Messerschmitt in 1958). Messerschmitt ended the joint venture in 1965 by acquiring control of JFM AG and absorbing it within Messerschmitt in 1967. Within West Germany, Junkers GmbH was engaged in research on the future of aerospace transportation during the fifties and early-1960s. During this period, Junkers employed the famous Austrian engineer and space travel theorist, Eugen Sänger, who in 1961 completed work for the design of an advanced orbital spacecraft at Junkers. Junkers GmbH was absorbed within MBB and the Junkers name disappeared in 1969.

Junkers Jumo.

Junkers also ran an engine factory, and in 1923 they separated it from the parent to form its own company, Junkers Motorenwerke, or Jumo. This company expanded greatly in the 1920s and 30s, with factories spread across Germany. Jumo was the first company to produce a successful aircraft diesel engine in material numbers, the opposed-piston layout two stroke Jumo 205, and it was the first German company to offer a truly modern engine suitable for aviation in the form of the 650 hp, inverted-V12 Jumo 210. But, with the rapid advances in airframes, after a few years this engine was considered to be underpowered, causing Jumo to respond with the much larger Jumo 211, the most-produced German aviation engine of any type during the war years. Perhaps unsurprisingly, the 211 saw widespread use in Junkers bombers — most often in a "unitized" form for the Junkers Ju 88A, and also in the competing Heinkel He 111H medium bomber — but was little used otherwise, due largely to the better power output of the competing Daimler-Benz DB 601. Further development of the 211 led to the superb Jumo 213, which was in high demand for an increasingly large variety of late-war piston-engined aircraft. Their only attempt at an over-1,500 kW output piston engine, the Junkers Jumo 222, suffered from inadequate metallurgy and internal design for what was otherwise a very innovative engine design, with nearly 300 examples produced solely as test examples — the aviation engine firms of the Third Reich had considerable challenges in developing piston engines that could exceed the 1,500 kW output level that would be able to operate with proven combat reliability. However, the world's first production axial-flow compressor-equipped turbojet engine, emerged from the "Jumo" firm in 1944 as the Jumo 004, becoming the first turbojet engine to be considered of production quality, and was used in the then revolutionary Messerschmitt Me 262A jet fighter.

Products.

Aircraft.

The Junkers firm's early aircraft were identified by the letter J for Junkers followed by an Arabic type number. From 1919 they introduced an additional sales designation using the same number but prefixed by a letter indicating the role of the aircraft:  Just once, the same number was used to identify two different completed types. This pair was the T 23 and G23, both also known as J 23.  During World War I, machines in service used the regular Idflieg aircraft designation system to specify their design's purpose, also promoted by the Flugzeugmeisterei (Air Ministry), again a letter number system indicating role:  The best known and most confusing example is the Junkers J 4 armored-fuselage, all-metal sesquiplane, known to the military as the Junkers J.I.  The single letter company prefix was not replaced by the twin-letter Ju prefix until 1933. This RLM system – from the Third Reich's air ministry – applied to all German manufacturers; the first Junkers aircraft to receive a Ju number was the W 33, so retrospectively it became the Ju 33. However, earlier aircraft built in Moscow like the H 21 were often described by a Ju number, e.g. Ju 21.

Aircraft engines.

All Junkers diesel engines were two stroke, opposed piston designs, an arrangement he invented in the early 1890s. It was intended to provide an alternative to Nicholaus Otto's patented four stroke which would run on low grade fuels such as blast furnace waste gases. By 1896 Junkers engines were generating electrical power in steelworks.

Junkers Flugzeug- und Motorenwerke AG (JFM, earlier JCO or JKO in World War I, English: Junkers Aircraft and Motor Works) more commonly Junkers, was a major German aircraft and aircraft engine manufacturer. It produced some of the world's most innovative and best-known airplanes over the course of its fifty-plus year history in Dessau, Germany. It was founded there in 1895 by Hugo Junkers, initially manufacturing boilers and radiators. During World War I, and following the war, the company became famous for its pioneering all-metal aircraft. During World War II the company produced some of the most successful Luftwaffe planes, as well as piston and jet aircraft engines, albeit in the absence of its founder, who had been removed by the Nazis in 1934.

容克斯飞机与发动机制造厂(,一般直接通称「容克斯」)是德国一家飞机制造商,它在其创立后50年内研制出了当时世界上最先进的几种飞机。容克斯公司由胡戈·容克斯于1895年所创立,最初仅生产锅炉与发动机,第一次世界大战期间,容克斯研制了当时世上最先进的全金属单翼机。在二战期间,尽管容克斯本人被纳粹份子所斩除,其公司仍成功研制出数种极为先进的飞机,如著名的“斯图卡”Ju 87俯冲轰炸机,以及“铁安妮”Ju 52运输机。