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# Cottingley Fairies
## 1917 photographs
In mid-1917 nine-year-old Frances Griffiths and her mother`{{snd}}`{=mediawiki}both newly arrived in England from South Africa`{{snd}}`{=mediawiki}were staying with Frances\'s aunt, Elsie Wright\'s mother, Polly, in the village of Cottingley in West Yorkshire; Elsie was then 16 years old. The two girls often played together beside the beck at the bottom of the garden, much to their mothers\' annoyance, because they frequently came back with wet feet and clothes. Frances and Elsie said they only went to the beck to see the fairies, and to prove it, Elsie borrowed her father\'s camera, a Midg quarter-plate. The girls returned about 30 minutes later, \"triumphant\".
Elsie\'s father, Arthur, was a keen amateur photographer, and had set up his own darkroom. The picture on the photographic plate he developed showed Frances behind a bush in the foreground, on which four fairies appeared to be dancing. Knowing his daughter\'s artistic ability, and that she had spent some time working in a photographer\'s studio, he dismissed the figures as cardboard cutouts. Two months later the girls borrowed his camera again, and this time returned with a photograph of Elsie sitting on the lawn holding out her hand to a 1 ft gnome. Exasperated by what he believed to be \"nothing but a prank\", and convinced that the girls must have tampered with his camera in some way, Arthur Wright refused to lend it to them again. His wife Polly, however, believed the photographs to be authentic.
Towards the end of 1918, Frances sent a letter to Johanna Parvin, a friend in Cape Town, South Africa, where Frances had lived for most of her life, enclosing the photograph of herself with the fairies. On the back she wrote \"It is funny, I never used to see them in Africa. It must be too hot for them there.\"
The photographs became public in mid-1919, after Elsie\'s mother attended a meeting of the Theosophical Society in Bradford. The lecture that evening was on \"fairy life\", and at the end of the meeting Polly Wright showed the two fairy photographs taken by her daughter and niece to the speaker. As a result, the photographs were displayed at the society\'s annual conference in Harrogate, held a few months later. There they came to the attention of a leading member of the society, Edward Gardner. One of the central beliefs of theosophy is that humanity is undergoing a cycle of evolution, towards increasing \"perfection\", and Gardner recognised the potential significance of the photographs for the movement:
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# Cottingley Fairies
## Initial examinations {#initial_examinations}
Gardner sent the prints along with the original glass-plate negatives to Harold Snelling, a photography expert. Snelling\'s opinion was that \"the two negatives are entirely genuine, unfaked photographs \... \[with\] no trace whatsoever of studio work involving card or paper models\". He did not go so far as to say that the photographs showed fairies, stating only that \"these are straight forward photographs of whatever was in front of the camera at the time\". Gardner had the prints \"clarified\" by Snelling, and new negatives produced, \"more conducive to printing\", for use in the illustrated lectures he gave around Britain. Snelling supplied the photographic prints which were available for sale at Gardner\'s lectures.
Author and prominent spiritualist Sir Arthur Conan Doyle learned of the photographs from the editor of the spiritualist publication *Light*. Doyle had been commissioned by *The Strand Magazine* to write an article on fairies for their Christmas issue, and the fairy photographs \"must have seemed like a godsend\" according to broadcaster and historian Magnus Magnusson. Doyle contacted Gardner in June 1920 to determine the background to the photographs, and wrote to Elsie and her father to request permission from the latter to use the prints in his article. Arthur Wright was \"obviously impressed\" that Doyle was involved, and gave his permission for publication, but he refused payment on the grounds that, if genuine, the images should not be \"soiled\" by money.
Gardner and Doyle sought a second expert opinion from the photographic company Kodak. Several of the company\'s technicians examined the enhanced prints, and although they agreed with Snelling that the pictures \"showed no signs of being faked\", they concluded that \"this could not be taken as conclusive evidence \... that they were authentic photographs of fairies\". Kodak declined to issue a certificate of authenticity. Gardner believed that the Kodak technicians might not have examined the photographs entirely objectively, observing that one had commented \"after all, as fairies couldn\'t be true, the photographs must have been faked somehow\". The prints were also examined by another photographic company, Ilford, who reported unequivocally that there was \"some evidence of faking\". Gardner and Doyle, perhaps rather optimistically, interpreted the results of the three expert evaluations as two in favour of the photographs\' authenticity and one against.
Doyle also showed the photographs to the physicist and pioneering psychical researcher Sir Oliver Lodge, who believed the photographs to be fake. He suggested that a troupe of dancers had masqueraded as fairies, and expressed doubt as to their \"distinctly \'Parisienne{{\'\"}} hairstyles.
On 4 October 2018 the first two of the photographs, *Alice and the Fairies* and *Iris and the Gnome,* were to be sold by Dominic Winter Auctioneers, in Gloucestershire. The prints, suspected to have been made in 1920 to sell at theosophical lectures, were expected to bring £700--£1000 each. As it turned out, *Iris with the Gnome* sold for a hammer price of £5,400 (plus 24% buyer\'s premium incl. VAT), while *Alice and the Fairies* sold for a hammer price of £15,000 (plus 24% buyer\'s premium incl. VAT).
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# Cottingley Fairies
## 1920 photographs {#photographs_1}
Doyle was preoccupied with organising an imminent lecture tour of Australia, and in July 1920, sent Gardner to meet the Wright family. By this point, Frances was living with her parents in Scarborough, but Elsie\'s father told Gardner that he had been so certain the photographs were fakes that while the girls were away he searched their bedroom and the area around the beck (stream), looking for scraps of pictures or cutouts, but found nothing \"incriminating\".
Gardner believed the Wright family to be honest and respectable. To place the matter of the photographs\' authenticity beyond doubt, he returned to Cottingley at the end of July with two W. Butcher & Sons Cameo folding plate cameras and 24 secretly marked photographic plates. Frances was invited to stay with the Wright family during the school summer holiday so that she and Elsie could take more pictures of the fairies. Gardner described his briefing in his 1945 *Fairies: A Book of Real Fairies*: `{{blockquote|I went off, to Cottingley again, taking the two cameras and plates from London, and met the family and explained to the two girls the simple working of the cameras, giving one each to keep. The cameras were loaded, and my final advice was that they need go up to the glen only on fine days as they had been accustomed to do before and ''tice'' the fairies, as they called their way of attracting them, and see what they could get. I suggested only the most obvious and easy precautions about lighting and distance, for I knew it was essential they should feel free and unhampered and have no burden of responsibility. If nothing came of it all, I told them, they were not to mind a bit.<ref name=Cooper/>}}`{=mediawiki} Until 19 August the weather was unsuitable for photography. Because Frances and Elsie insisted that the fairies would not show themselves if others were watching, Elsie\'s mother was persuaded to visit her sister\'s for tea, leaving the girls alone. In her absence the girls took several photographs, two of which appeared to show fairies. In the first, *Frances and the Leaping Fairy*, Frances is shown in profile with a winged fairy close by her nose. The second, *Fairy offering Posy of Harebells to Elsie*, shows a fairy either hovering or tiptoeing on a branch, and offering Elsie a flower. Two days later the girls took the last picture, *Fairies and Their Sun-Bath*.
The plates were packed in cotton wool and returned to Gardner in London, who sent an \"ecstatic\" telegram to Doyle, by then in Melbourne. Doyle wrote back:
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# Cottingley Fairies
## Publication and reaction {#publication_and_reaction}
Doyle\'s article in the December 1920 issue of *The Strand* contained two higher-resolution prints of the 1917 photographs, and sold out within days of publication. To protect the girls\' anonymity, Frances and Elsie were called Alice and Iris respectively, and the Wright family was referred to as the \"Carpenters\". An enthusiastic and committed spiritualist, Doyle hoped that if the photographs convinced the public of the existence of fairies then they might more readily accept other psychic phenomena. He ended his article with the words: `{{blockquote|The recognition of their existence will jolt the material twentieth-century mind out of its heavy ruts in the mud, and will make it admit that there is a glamour and mystery to life. Having discovered this, the world will not find it so difficult to accept that spiritual message supported by physical facts which have already been put before it.<ref name=Roden/>}}`{=mediawiki} Early press coverage was \"mixed\", generally a combination of \"embarrassment and puzzlement\"; though Japanese scholar Kaori Inuma has noted that there were also open and positive assessments. The historical novelist and poet Maurice Hewlett published a series of articles in the literary journal *John O\' London\'s Weekly*, in which he concluded: \"And knowing children, and knowing that Sir Arthur Conan Doyle has legs, I decide that the Miss Carpenters have pulled one of them.\" The London newspaper *Truth* on 5 January 1921 expressed a similar view; \"For the true explanation of these fairy photographs what is wanted is not a knowledge of occult phenomena but a knowledge of children.\" Some public figures were more sympathetic. Margaret McMillan, the educational and social reformer, wrote: \"How wonderful that to these dear children such a wonderful gift has been vouchsafed.\" The novelist Henry De Vere Stacpoole decided to take the fairy photographs and the girls at face value. In a letter to Gardner he wrote: \"Look at Alice\'s \[Frances\'\] face. Look at Iris\'s \[Elsie\'s\] face. There is an extraordinary thing called Truth which has 10 million faces and forms -- it is God\'s currency and the cleverest coiner or forger can\'t imitate it.\"
Major John Hall-Edwards, a keen photographer and pioneer of medical X-ray treatments in Britain, was a particularly vigorous critic: `{{blockquote|On the evidence I have no hesitation in saying that these photographs could have been "faked". I criticize the attitude of those who declared there is something supernatural in the circumstances attending to the taking of these pictures because, as a medical man, I believe that the inculcation of such absurd ideas into the minds of children will result in later life in manifestations and nervous disorder and mental disturbances.<ref name=Cooper/>}}`{=mediawiki} Doyle used the later photographs in 1921 to illustrate a second article in *The Strand*, in which he described other accounts of fairy sightings. The article formed the foundation for his 1922 book *The Coming of the Fairies*. As before, the photographs were received with mixed credulity. Sceptics noted that the fairies \"looked suspiciously like the traditional fairies of nursery tales\" and that they had \"very fashionable hairstyles\".
## Gardner\'s final visit {#gardners_final_visit}
Gardner made a final visit to Cottingley in August 1921. He again brought cameras and photographic plates for Frances and Elsie, but was accompanied by the occultist Geoffrey Hodson. Although neither of the girls claimed to see any fairies, and there were no more photographs, \"on the contrary, he \[Hodson\] saw them \[fairies\] everywhere\" and wrote voluminous notes on his observations.
By now Elsie and Frances were tired of the whole fairy business. Years later Elsie looked at a photograph of herself and Frances taken with Hodson and said: \"Look at that, fed up with fairies.\" Both Elsie and Frances later admitted that they \"played along\" with Hodson \"out of mischief\", and that they considered him \"a fake\".
## Later investigations {#later_investigations}
Public interest in the Cottingley Fairies gradually subsided after 1921. Elsie and Frances both eventually married, moved away from the area and each lived overseas for varying periods of time. In 1966, a reporter from the *Daily Express* newspaper traced Elsie, who was by then back in England. She admitted in an interview given that year that the fairies might have been \"figments of my imagination\", but left open the possibility she believed that she had somehow managed to photograph her thoughts. The media subsequently became interested in Frances and Elsie\'s photographs once again. BBC television\'s *Nationwide* programme investigated the case in 1971, but Elsie stuck to her story: \"I\'ve told you that they\'re photographs of figments of our imagination, and that\'s what I\'m sticking to\".
Elsie and Frances were interviewed by journalist Austin Mitchell in September 1976, for a programme broadcast on Yorkshire Television. When pressed, both women agreed that \"a rational person doesn\'t see fairies\", but they denied having fabricated the photographs. In 1978 the magician and scientific sceptic James Randi and a team from the Committee for the Scientific Investigation of Claims of the Paranormal examined the photographs, using a \"computer enhancement process\". They concluded that the photographs were fakes, and that strings could be seen supporting the fairies. Geoffrey Crawley, editor of the *British Journal of Photography*, undertook a \"major scientific investigation of the photographs and the events surrounding them\", published between 1982 and 1983, \"the first major postwar analysis of the affair\". He also concluded that the pictures were fakes.
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# Cottingley Fairies
## Confession
In 1983, the cousins admitted in an article published in the magazine *The Unexplained* that the photographs had been faked, although both maintained that they really had seen fairies. Elsie had copied illustrations of three dancing fairies by Claude Shepperson from a book that Frances had brought back with her from South Africa. This was the *Princess Mary\'s Gift Book*, published towards the beginning of the war. Elsie changed few details but added wings. It is possible that a poem attached to the images by Alfred Noyes also inspired Elsie and Frances. They said they had then cut out the cardboard figures and supported them with hatpins, disposing of their props in the beck once the photograph had been taken. But the cousins disagreed about the fifth and final photograph, which Doyle in his *The Coming of the Fairies* described in this way:
Elsie maintained it was a fake, just like all the others, but Frances insisted that it was genuine. In an interview given in the early 1980s Frances said: `{{blockquote|It was a wet Saturday afternoon and we were just mooching about with our cameras and Elsie had nothing prepared. I saw these fairies building up in the grasses and just aimed the camera and took a photograph.<ref name=Cooper/>}}`{=mediawiki} Both Frances and Elsie claimed to have taken the fifth photograph. In a letter published in *The Times* newspaper on 9 April 1983, Geoffrey Crawley explained the discrepancy by suggesting that the photograph was \"an unintended double exposure of fairy cutouts in the grass\", and thus \"both ladies can be quite sincere in believing that they each took it\".
In a 1985 interview on Yorkshire Television\'s *Arthur C. Clarke\'s World of Strange Powers*, Elsie said that she and Frances were too embarrassed to admit the truth after fooling Doyle, the author of Sherlock Holmes: \"Two village kids and a brilliant man like Conan Doyle -- well, we could only keep quiet.\" In the same interview Frances said: \"I never even thought of it as being a fraud -- it was just Elsie and I having a bit of fun and I can\'t understand to this day why they were taken in -- they wanted to be taken in.\"
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# Cottingley Fairies
## Subsequent history {#subsequent_history}
thumb\|right\|upright=0.5\|Elsie Wright and Frances Griffiths, June 1917
Frances died in 1986, and Elsie in 1988. Prints of their photographs of the fairies, along with a few other items including a first edition of Doyle\'s book *The Coming of the Fairies*, were sold at auction in London for £21,620 in 1998. That same year, Geoffrey Crawley sold his Cottingley Fairy material to the National Museum of Film, Photography and Television in Bradford (now the National Science and Media Museum), where it is on display. The collection included prints of the photographs, two of the cameras used by the girls, watercolours of fairies painted by Elsie, and a nine-page letter from Elsie admitting to the hoax. The glass photographic plates were bought for £6,000 by an unnamed buyer at a London auction held in 2001.
Frances\'s daughter, Christine Lynch, appeared in an episode of the television programme *Antiques Roadshow* in Belfast, broadcast on BBC One in January 2009, with the photographs and one of the cameras given to the girls by Doyle. Christine told the expert, Paul Atterbury, that she believed, as her mother had done, that the fairies in the fifth photograph were genuine. Atterbury estimated the value of the items at between £25,000 and £30,000. The first edition of Frances\'s memoirs was published a few months later, under the title *Reflections on the Cottingley Fairies*. The book contains correspondence, sometimes \"bitter\", between Elsie and Frances. In one letter, dated 1983, Frances wrote: `{{blockquote|I hated those photographs from the age of 16 when Mr Gardner presented me with a bunch of flowers and wanted me to sit on the platform [at a Theosophical Society meeting] with him. I realised what I was in for if I did not keep myself hidden.<ref>{{cite news |last=Clayton |first=Emma |title=Cottingley Fairies Back in the Spotlight |date=14 July 2009 |newspaper=Bradford Telegraph & Argus |url=http://www.thetelegraphandargus.co.uk/news/4492364.Book_reveals_story_behind_the_Fairies/ |access-date=3 May 2010 |mode=cs2}}</ref>}}`{=mediawiki}
The 1997 films *FairyTale: A True Story* and *Photographing Fairies* were inspired by the events surrounding the Cottingley Fairies. The photographs were parodied in a 1994 book written by Terry Jones and Brian Froud, *Lady Cottington\'s Pressed Fairy Book*. In A. J. Elwood\'s 2021 novel, *The Cottingley Cuckoo*, a series of letters were written soon after the Cottingley fairy photographs were published claiming further sightings of fairies and proof of their existence.
In 2017 a further two fairy photographs were presented as evidence that the girls\' parents were part of the conspiracy. Dating from 1917 and 1918, both photographs are poorly executed copies of two of the original fairy photographs. One was published in 1918 in *The Sphere* newspaper, which was before the originals had been seen by anyone outside the girls\' immediate family.
In 2019, a print of the first of the five photographs sold for £1,050. A print of the second was also put up for sale but failed to sell as it did not meet its £500 reserve price. The pictures previously belonged to the Reverend George Vale Owen. In December 2019, the third camera used to take the images was acquired by the National Science and Media Museum
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# Unitary patent
--
--
: European patent with unitary effect
The **European patent with unitary effect**, also known as the **unitary patent**, is a European patent which benefits from unitary effect in the participating member states of the European Union.`{{refn|States only participate in the unitary patent after they ratify the [[Agreement on a Unified Patent Court|UPC Agreement]] and participate in the enhanced cooperation regarding the unitary patent. All EU member states participated, except Spain and Croatia.|group=notes}}`{=mediawiki} Unitary effect means the patent has a common legal status throughout all the participating states, eliminating scenarios in which a patent may be invalidated by courts in one participating member state yet upheld by courts in another. Unitary effect may be requested by the proprietor within one month of grant of a European patent, replacing validation of the European patent in the individual countries concerned. Infringement and revocation proceedings are conducted before the Unified Patent Court (UPC), which decisions have a uniform effect for the unitary patent in the participating member states as a whole rather than in each country individually. The unitary patent may be only limited, transferred or revoked, or lapse, in respect of all the participating Member States. Licensing is however possible for part of the unitary territory. The unitary patent may coexist with nationally enforceable patents (\"classical\" patents) in the non-participating states. The unitary patent\'s stated aims are to make access to the patent system \"easier, less costly and legally secure within the European Union\" and \"the creation of uniform patent protection throughout the Union\".
European patents are granted in English, French, or German and the unitary effect will not require further translations after a transition period.`{{refn|There is a transition period of maximum 12 years from 1 June 2023 during which one translation must be filed, either into English if the application is in French or German, or into any EU official language if the application was in English.|group=notes}}`{=mediawiki} The maintenance fees of the unitary patents are lower than the sum of the renewal fees for national patents of the corresponding area, being equivalent to the combined maintenance fees of Germany, France, the UK and the Netherlands (although the UK is no longer participating following Brexit).
The negotiations which resulted in the unitary patent can be traced back to various initiatives dating to the 1970s. At different times, the project, or very similar projects, have been referred to as the \"European Union patent\" (the name used in the EU treaties, which serve as the legal basis for EU competency), \"EU patent\", \"Community patent\", \"European Community Patent\", \"EC patent\" and \"COMPAT\".
On 17 December 2012, agreement was reached between the European Council and European Parliament on the two EU regulations`{{refn|Regulation 1257/2012 and Regulation 1260/2012|group=notes}}`{=mediawiki} that made the unitary patent possible through enhanced cooperation at EU level. The legality of the two regulations was challenged by Spain and Italy, but all their claims were rejected by the European Court of Justice. Italy subsequently joined the unitary patent regulation in September 2015, so that all EU member states except Spain and Croatia now participate in the enhanced cooperation for a unitary patent. Unitary effect of newly granted European patents will be available from the date when the related Unified Patent Court Agreement enters into force for those EU countries that have also ratified the UPC,`{{refn|As of June 2022, 16 EU countries have ratified the UPC: Austria, Belgium, Bulgaria, Denmark, Estonia, Finland, France, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Portugal, Slovenia, Sweden |group=notes|name="UPC entry into force"}}`{=mediawiki} and will extend to those participating member states for which the UPC Agreement enters into force at the time of registration of the unitary patent. Previously granted unitary patents will not automatically get their unitary effect extended to the territory of participating states which ratify the UPC agreement at a later date.
The unitary patent system applies since 1 June 2023, the date of entry into force of the UPC Agreement.
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# Unitary patent
## Background
### Legislative history {#legislative_history}
In 2009, three draft documents were published regarding a community patent: a European patent in which the European Community was designated:
1. Council regulation on the community patent,
2. Agreement on the European and Community Patents Court (open to the European Community and all states of the European Patent Convention)
3. Decision to open negotiations regarding this Agreement
Based on those documents, the European Council requested on 6 July 2009 an opinion from the Court of Justice of the European Union, regarding the compatibility of the envisioned Agreement with EU law: \"\'Is the envisaged agreement creating a Unified Patent Litigation System (currently named European and Community Patents Court) compatible with the provisions of the Treaty establishing the European Community?'\"
In December 2010, the use of the enhanced co-operation procedure, under which Articles 326--334 of the Treaty on the Functioning of the European Union provides that a group of member states of the European Union can choose to co-operate on a specific topic, was proposed by twelve Member States to set up a unitary patent applicable in all participating European Union Member States. The use of this procedure had only been used once in the past, for harmonising rules regarding the applicable law in divorce across several EU Member States.
In early 2011, the procedure leading to the enhanced co-operation was reported to be progressing. Twenty-five Member States had written to the European Commission requesting to participate, with Spain and Italy remaining outside, primarily on the basis of ongoing concerns over translation issues. On 15 February, the European Parliament approved the use of the enhanced co-operation procedure for unitary patent protection by a vote of 471 to 160, and on 10 March 2011 the Council gave their authorisation. Two days earlier, on 8 March 2011, the Court of Justice of the European Union had issued its opinion, stating that the draft Agreement creating the European and Community Patent Court would be incompatible with EU law. The same day, the Hungarian Presidency of the Council insisted that this opinion would not affect the enhanced co-operation procedure.
In November 2011, negotiations on the enhanced co-operation system were reportedly advancing rapidly---too fast, in some views. It was announced that implementation required an enabling European Regulation, and a Court agreement between the states that elect to take part. The European Parliament approved the continuation of negotiations in September. A draft of the agreement was issued on 11 November 2011 and was open to all member states of the European Union, but not to other European Patent Convention states. However, serious criticisms of the proposal remained mostly unresolved. A meeting of the Competitiveness Council on 5 December failed to agree on the final text. In particular, there was no agreement on where the Central Division of a Unified Patent Court should be located, \"with London, Munich and Paris the candidate cities.\"
The Polish Presidency acknowledged on 16 December 2011 the failure to reach an agreement \"on the question of the location of the seat of the central division.\" The Danish Presidency therefore inherited the issue. According to the President of the European Commission in January 2012, the only question remaining to be settled was the location of the Central Division of the Court. However, evidence presented to the UK House of Commons European Scrutiny Committee in February suggested that the position was more complicated. At an EU summit at the end of January 2012, participants agreed to press on and finalise the system by June. On 26 April, Herman Van Rompuy, President of the European Council, wrote to members of the council, saying \"This important file has been discussed for many years and we are now very close to a final deal,\.... This deal is needed now, because this is an issue of crucial importance for innovation and growth. I very much hope that the last outstanding issue will be sorted out at the May Competitiveness Council. If not, I will take it up at the June European Council.\" The Competitiveness Council met on 30 May and failed to reach agreement.
A compromise agreement on the seat(s) of the unified court was eventually reached at the June European Council (28--29 June 2012), splitting the central division according to technology between Paris (the main seat), London and Munich. However, on 2 July 2012, the European Parliament decided to postpone the vote following a move by the European Council to modify the arrangements previously approved by MEPs in negotiations with the European Council. The modification was considered controversial and included the deletion of three key articles (6--8) of the legislation, seeking to reduce the competence of the European Union Court of Justice in unitary patent litigation. On 9 July 2012, the Committee on Legal Affairs of the European Parliament debated the patent package following the decisions adopted by the General Council on 28--29 June 2012 in camera in the presence of MEP Bernhard Rapkay. A later press release by Rapkay quoted from a legal opinion submitted by the Legal Service of the European Parliament, which affirmed the concerns of MEPs to approve the decision of a recent EU summit to delete said articles as it \"nullifies central aspects of a substantive patent protection\". A Europe-wide uniform protection of intellectual property would thus not exist with the consequence that the requirements of the corresponding EU treaty would not be met and that the European Court of Justice could therefore invalidate the legislation. By the end of 2012 a new compromise was reached between the European Parliament and the European Council, including a limited role for the European Court of Justice. The Unified Court will apply the Unified Patent Court Agreement, which is considered national patent law from an EU law point of view, but still is equal for each participant. \[However the [draft statutory instrument](http://www.legislation.gov.uk/ukdsi/2016/9780111142899) aimed at implementation of the Unified Court and UPC in the UK provides for different infringement laws for: European patents (unitary or not) litigated through the Unified Court; European patents (UK) litigated before UK courts; and national patents\]. The legislation for the enhanced co-operation mechanism was approved by the European Parliament on 11 December 2012 and the regulations were signed by the European Council and European Parliament officials on 17 December 2012.
On 30 May 2011, Italy and Spain challenged the council\'s authorisation of the use of enhanced co-operation to introduce the trilingual (English, French, German) system for the unitary patent, which they viewed as discriminatory to their languages, with the CJEU on the grounds that it did not comply with the EU treaties. In January 2013, Advocate General Yves Bot delivered his recommendation that the court reject the complaint. Suggestions by the Advocate General are advisory only, but are generally followed by the court. The case was dismissed by the court in April 2013, however Spain launched two new challenges with the EUCJ in March 2013 against the regulations implementing the unitary patent package. The court hearing for both cases was scheduled for 1 July 2014. Advocate-General Yves Bot published his opinion on 18 November 2014, suggesting that both actions be dismissed (`{{ECLI|ECLI:EU:C:2014:2380}}`{=mediawiki} and `{{ECLI|ECLI:EU:C:2014:2381}}`{=mediawiki}). The court handed down its decisions on 5 May 2015 as `{{ECLI|ECLI:EU:C:2015:298}}`{=mediawiki} and `{{ECLI|ECLI:EU:C:2015:299}}`{=mediawiki} fully dismissing the Spanish claims. Following a request by its government, Italy became a participant of the unitary patent regulations in September 2015.
### European patents {#european_patents}
European patents are granted in accordance with the provisions of the European Patent Convention (EPC), via a unified procedure before the European Patent Office (EPO). While upon filing of a European patent application, all 39 Contracting States are automatically designated, a European patent becomes a bundle of \"national\" European patents upon grant. In contrast to the unified character of a European patent application, a granted European patent has, in effect, no unitary character, except for the centralized opposition procedure (which can be initiated within 9 months from grant, by somebody else than the patent proprietor), and the centralized limitation and revocation procedures (which can only be instituted by the patent proprietor). In other words, a European patent in one Contracting State, i.e. a \"national\" European patent,`{{refn|There is no consistent usage of a particular expression to refer to "the European patent in a particular designated Contracting State for which it is granted". The article uses the expression "a "national" European patent"|group=notes}}`{=mediawiki} is effectively independent of the same European patent in each other Contracting State, except for the opposition, limitation and revocation procedures. The enforcement of a European patent is dealt with by national law. The abandonment, revocation or limitation of the European patent in one state does not affect the European patent in other states.
While the EPC already provided the possibility for a group of member states to allow European patents to have a unitary character also after grant, until now, only Liechtenstein and Switzerland have opted to create a unified protection area (see Unitary patent (Switzerland and Liechtenstein)).
By requesting unitary effect within one month of grant, the patent proprietor is now able to obtain uniform protection in the participating members states of the European Union in a single step, considerably simplifying obtaining patent protection in a large part of the EU. The unitary patent system co-exists with national patent systems and European patent without unitary effects. The unitary patent does not cover EPC countries that are not member of the European Union, such as UK or Turkey.
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# Unitary patent
## Legal basis and implementation {#legal_basis_and_implementation}
The implementation of the unitary patent is based on three legal instruments:
- Regulation (EU) No 1257/2012 of the European Parliament and of the Council of 17 December 2012 implementing enhanced cooperation in the area of the creation of unitary patent protection;
- Council Regulation (EU) No 1260/2012 of 17 December 2012 implementing enhanced cooperation in the area of the creation of unitary patent protection with regard to the applicable translation arrangements;
- Agreement on a Unified Patent Court.
Thus the unitary patent is based on EU law as well as the European Patent Convention (EPC). `{{EPC Article|142}}`{=mediawiki} provides the legal basis for establishing a common system of patents for Parties to the EPC. as authorized by `{{EPC Article|143|1}}`{=mediawiki}. These tasks include the collection of renewal fees and registration of unitary effect upon grant, recording licenses and statements that licenses are available to any person. Decisions of the European Patent Office regarding the unitary patent are open to appeal to the Unified Patent Court, rather than to the EPO Boards of Appeal.`{{refn|[[s:Agreement on a Unified Patent Court#Article 32 .E2.80.93 Competence of the Court|Article 32(1)i, Agreement on a Unified Patent Court]], implementing Article 9.3 of Regulation (EU) No 1257/2012.<ref name="32012R1257"/>}}`{=mediawiki}
### Translation requirements for the European patent with unitary effect {#translation_requirements_for_the_european_patent_with_unitary_effect}
For a unitary patent, ultimately no translation will be required (except under certain circumstances in the event of a dispute), which is expected to significantly reduce the cost for protection in the whole area. However, Regulation 1260/2012 provides that, during a transitional period of minimum six years and no more than twelve years, one translation needs to be provided. Namely, a full translation of the European patent specification needs to be provided either into English if the language of the proceedings at the EPO was French or German, or into any other EU official language if the language of the proceedings at the EPO was English. Such translation will have no legal effect and will be \"for information purposes only". In addition, machine translations will be provided, which will be, in the words of the regulation, \"for information purposes only and should not have any legal effect\".
#### Comparison with the current translation requirements for traditional bundle European patents {#comparison_with_the_current_translation_requirements_for_traditional_bundle_european_patents}
In several EPC contracting states, for the national part of a traditional bundle European patent (i.e., for a European patent without unitary effect), a translation has to be filed within a three-month time limit after the publication of grant in the European Patent Bulletin under `{{EPC Article|65}}`{=mediawiki},`{{refn|{{EPC Article|2|2}} provides that "[t]he European patent shall, in each of the Contracting States for which it is granted, have the effect of and be subject to the same conditions as a national patent granted by that State, unless this Convention provides otherwise." The provision of Article 65 EPC may therefore be viewed as an exception to Article 2(2) EPC. See also [[London Agreement (2000)]].|group=notes}}`{=mediawiki} otherwise the patent is considered never to have existed (void ab initio) in that state. For the 22 parties to the London Agreement, this requirement has already been abolished or reduced (e.g. by dispensing with the requirement if the patent is available in English, and/or only requiring translation of the claims).
Translation requirements for the participating states in the enhanced cooperation for a unitary patent are shown below:
+------------------------------------------------------------------------------------------------------------------------+-----------------------------------------------------------------------------------+---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| Participating member State (**bold: unitary patents apply**) | Translation requirements for a European patent without unitary effect | Translation requirements for a European patent with unitary effect |
+========================================================================================================================+===================================================================================+=======================================================================================================================================================================================+
| **Belgium, France, Germany,** Ireland, **Luxembourg** | None | During a transitional period of minimum 6 years and maximum 12 years: one translation, so that the unitary patent is available in English and at least another EU official language.\ |
| | | After the transitional period: none. |
+------------------------------------------------------------------------------------------------------------------------+-----------------------------------------------------------------------------------+---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| **Latvia, Lithuania**, **Slovenia** | Claims in the official language of the concerned State | |
+------------------------------------------------------------------------------------------------------------------------+-----------------------------------------------------------------------------------+---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| **Denmark, Finland,** Hungary, **Netherlands, Sweden** | Description in English, claims in the official language of the concerned State | |
+------------------------------------------------------------------------------------------------------------------------+-----------------------------------------------------------------------------------+---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| **Austria, Bulgaria,** Cyprus, Czech Republic, **Estonia,** Greece, **Malta**, Poland, **Portugal, Romania**, Slovakia | Translation of the complete patent in an official language of the concerned State | |
+------------------------------------------------------------------------------------------------------------------------+-----------------------------------------------------------------------------------+---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
### Unitary patent as an object of property {#unitary_patent_as_an_object_of_property}
Article 7 of Regulation 1257/2012 provides that, as an object of property, a European patent with unitary effect will be treated \"in its entirety and in all participating Member States as a national patent of the participating Member State in which that patent has unitary effect and in which the applicant had her/his residence or principal place of business or, by default, had a place of business on the date of filing the application for the European patent.\" When the applicant had no domicile in a participating Member State, German law will apply. Ullrich has the criticized the system, which is similar to the Community Trademark and the Community Design, as being \"in conflict with both the purpose of the creation of unitary patent protection and with primary EU law.\"
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# Unitary patent
## Legal basis and implementation {#legal_basis_and_implementation}
### Agreement on a Unified Patent Court {#agreement_on_a_unified_patent_court}
The Agreement on a Unified Patent Court provides the legal basis for the Unified Patent Court (UPC): a patent court for European patents (with and without unitary effect), with jurisdiction in those countries where the Agreement is in effect. In addition to regulations regarding the court structure, it also contains substantive provisions relating to the right to prevent use of an invention and allowed use by non-patent proprietors (e.g. for private non-commercial use), preliminary and permanent injunctions. Entry into force for the UPC took place after Germany deposited its instrument of ratification of the UPC Agreement, which triggered the countdown until the Agreement\'s entry into force on June 1, 2023.
#### Parties
The UPC Agreement was signed on 19 February 2013 by 24 EU member states, including all states then participating in the enhanced co-operation measures except Bulgaria and Poland. Bulgaria signed the agreement on 5 March 2013 following internal administrative procedures. Italy, which did not originally join the enhanced co-operation measures but subsequently signed up, did sign the UPC agreement. The agreement remains open to accession for all remaining EU member states, with all European Union Member States except Spain and Poland having signed the Agreement. States which do not participate in the unitary patent regulations can still become parties to the UPC agreement, which would allow the new court to handle European patents validated in the country.
On 18 January 2019, Kluwer Patent Blog wrote, \"a recurring theme for some years has been that \'the UPC will start next year\'\". Then, Brexit and German constitutional court complaint were considered as the main obstacles. The German constitutional court first decided in a decision of 13 February 2020 against the German ratification of the Agreement on the ground that the German Parliament did not vote with the required majority (2/3 according to the judgement). After a second vote and further, this time unsuccessful, constitutional complaints, Germany formally ratified the UPC Agreement on 7 August 2021. While the UK ratified the agreement in April 2018, the UK later withdrew from the Agreement following Brexit.
As of the entry into force of the UPC on 1 June 2023, 17 countries had ratified the Agreement. Romania ratified the agreement in May 2024, and will join as the 18th participating member on 1 September 2024.
#### Jurisdiction
The Unified Patent Court has exclusive jurisdiction in infringement and revocation proceedings involving European patents with unitary effect, and during a transition period non-exclusive jurisdiction regarding European patents without unitary effect in the states where the Agreement applies, unless the patent proprietor decides to opt out. It furthermore has jurisdiction to hear cases against decisions of the European Patent Office regarding unitary patents. As a court of several member states of the European Union it may (Court of First Instance) or must (Court of Appeal) ask prejudicial questions to the European Court of Justice when the interpretation of EU law (including the two unitary patent regulations, but excluding the UPC Agreement) is not obvious.
#### Organization
The court has two instances: a court of first instance and a court of appeal. The court of appeal and the registry have their seats in Luxembourg, while the central division of the court of first instance would have its seat in Paris. The central division has a thematic branch in Munich (the London location has yet to be replaced by a new location within the EU). The court of first instance may further have local and regional divisions in all member states that wish to set up such divisions.
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# Unitary patent
## Legal basis and implementation {#legal_basis_and_implementation}
### Geographical scope of and request for unitary effect {#geographical_scope_of_and_request_for_unitary_effect}
While the regulations formally apply to all 25 member states participating in the enhanced cooperation for a unitary patent, from the date the UPC agreement has entered into force for the first group of ratifiers,`{{refn|group=notes|name="UPC entry into force"}}`{=mediawiki} unitary patents will only extend to the territory of those participating member states where the UPC Agreement had entered into force when the unitary effect was registered. If the unitary effect territory subsequently expands to additional participating member states for which the UPC Agreement later enters into force, this will be reflected for all subsequently registered unitary patents, but the territorial scope of the unitary effect of existing unitary patents will not be extended to these states.
Unitary effect can be requested up to one month after grant of the European patent directly at the EPO, with retroactive effect from the date of grant. However, according to the *Draft Rules Relating to Unitary Patent Protection*, unitary effect would be registered only if the European patent has been granted with the same set of claims`{{refn|A European patent may be granted by the EPO with claims which are, for one or more States, different from those applicable to the other designated States. This rare situation may arise by virtue of {{EPC Rule|18|2}} or {{EPC Rule|138}}.|group=notes}}`{=mediawiki} for all the 25 participating member states in the regulations,`{{refn|This requires that all 25 states participating in the [[Enhanced cooperation#Unitary patent|enhanced cooperation regulations]] have been designated upon filing of the European patent application. For European patent applications filed after 1 April 2009, all Contracting States party to the [[European Patent Convention|EPC]] at the time of filing of the application are automatically designated,<ref>{{cite web|url=http://www.epo.org/law-practice/legal-texts/html/guidelines/e/a_iii_11_2_2.htm|title=Guidelines for Examination: 11.2.2 Payment of designation fee|publisher=European Patent Office|date= April 2014}}</ref> although designations may be withdrawn before grant.<ref>{{cite web|url=http://www.epo.org/law-practice/legal-texts/html/guidelines/e/a_iii_11_3_8.htm|title=Guidelines for Examiniation: 11.3.8 Withdrawal of designation|publisher=European Patent Office|date=16 September 2013}}</ref> It was not possible to designate Malta before it became a party to the EPC on 1 March 2007.|group=notes}}`{=mediawiki} whether the unitary effect applies to them or not. European patents automatically become a bundle of \"national\" European patents upon grant. Upon the grant of unitary effect, the \"national\" European patents will retroactively be considered to never have existed in the territories where the unitary patent has effect. The unitary effect does not affect \"national\" European patents in states where the unitary patent does not apply. Any \"national\" European patents applying outside the \"unitary effect\" zone will co-exist with the unitary patent.
#### Special territories of participating member states {#special_territories_of_participating_member_states}
As the unitary patent is introduced by an EU regulation, it is expected to not only be valid in the mainland territory of the participating member states that are party to the UPC, but also in those of their special territories that are part of the European Union. As of April 2014, this includes the following fourteen territories:
- Cyprus: UN Buffer Zone
- Finland: Åland
- France: French Guiana, Guadeloupe, Martinique, Mayotte, Réunion, Saint Martin
- Germany: Büsingen am Hochrhein, Helgoland
- Greece: Mount Athos
- Portugal: Azores, Madeira
In addition to the territories above, the European Patent Convention has been extended by two member states participating in the enhanced cooperation for a unitary patent to cover some of their dependent territories outside the European Union: In following of those territories, the unitary patent is de facto extended through application of national (French, or Dutch) law:
- France: French Southern and Antarctic Lands, Saint Barthélemy, Saint-Pierre and Miquelon and Wallis and Futuna
- Netherlands: Caribbean Netherlands, Curaçao, Sint Maarten
However, the unitary patent does not apply in the French territories French Polynesia and New Caledonia as implementing legislation would need to be passed by those jurisdictions (rather than the French national legislation required in the other territories) and this has not been done.
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# Unitary patent
## Costs
+---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| ImageSize = width:auto height:180 barincrement:40 PlotArea = left:50 bottom:15 top:10 right:18 AlignBars = justify DateFormat = yyyy Period = from:0 till:5000 TimeAxis = orientation:vertical ScaleMajor = unit:year increment:1000 start:0 PlotData= |
| |
| ` color:skyblue width:40`\ |
| ` bar:2 from:start till:35 text:€ 35`\ |
| ` bar:3 from:start till:105 text:€ 105`\ |
| ` bar:4 from:start till:145 text:€ 145`\ |
| ` bar:5 from:start till:315 text:€ 315 `\ |
| ` bar:6 from:start till:475 text:€ 475`\ |
| ` bar:7 from:start till:630 text:€ 630`\ |
| ` bar:8 from:start till:815 text:€ 815`\ |
| ` bar:9 from:start till:990 text:€ 990`\ |
| ` bar:10 from:start till:1175 text:€ 1175`\ |
| ` bar:11 from:start till:1460 text:€ 1460`\ |
| ` bar:12 from:start till:1775 text:€ 1775`\ |
| ` bar:13 from:start till:2105 text:€ 2105`\ |
| ` bar:14 from:start till:2455 text:€ 2455`\ |
| ` bar:15 from:start till:2830 text:€ 2830 `\ |
| ` bar:16 from:start till:3240 text:€ 3240`\ |
| ` bar:17 from:start till:3640 text:€ 3640`\ |
| ` bar:18 from:start till:4055 text:€ 4055`\ |
| ` bar:19 from:start till:4455 text:€ 4455`\ |
| ` bar:20 from:start till:4855 text:€ 4855` |
+---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
: Yearly renewal fee for the unitary patent
The renewal fees are planned to be based on the cumulative renewal fees due in the four countries where European patents were most often validated in 2015 (Germany, France, the UK and the Netherlands). This is despite the UK leaving the unitary patent system following Brexit. The renewal fees of the unitary patent would thus be ranging from 35 Euro in the second year to 4855 in the 20th year. The renewal fees will be collected by the EPO, with the EPO keeping 50% of the fees and the other 50% being redistributed to the participating member states.
Translation requirements as well as the requirement to pay yearly patent maintenance fees in individual countries presently renders the European patent system costly to obtain protection in the whole of the European Union.
In an impact assessment from 2011, the European Commission estimated that the costs of obtaining a patent in all 27 EU countries would drop from over 32 000 euro (mainly due to translation costs) to 6 500 euro (for the combination of an EU, Spanish and Italian patent) due to introduction of the Unitary patent. Per capita costs of an EU patent were estimated at just 6 euro/million in the original 25 participating countries (and 12 euro/million in the 27 EU countries for protection with a Unitary, Italian and Spanish patent).
How the EU Commission has presented the expected cost savings has however been sharply criticized as exaggerated and based on unrealistic assumptions. The EU Commission has notably considered the costs for validating a European patent in 27 countries while in reality only about 1% of all granted European patents are currently validated in all 27 EU states. Based on more realistic assumptions, the cost savings are expected to be much lower than actually claimed by the commission. For example, the EPO calculated that for an average EP patent validated and maintained in 4 countries, the overall savings to be between 3% and 8%.
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# Unitary patent
## Statistics
During the first year of the unitary patent, that is, from 1 June 2023, to 31 May 2024, more than 27500 European patents with unitary effect have been registered. This corresponds to almost a quarter of all European patents granted during that period.
## Earlier attempts {#earlier_attempts}
### 1970s and 1980s: proposed Community Patent Convention {#s_and_1980s_proposed_community_patent_convention}
Work on a Community patent started in the 1970s, but the resulting Community Patent Convention (CPC) was a failure.
The \"Luxembourg Conference on the Community Patent\" took place in 1975 and the **Convention for the European Patent for the common market**, or (Luxembourg) Community Patent Convention (CPC), was signed at Luxembourg on 15 December 1975, by the 9 member states of the European Economic Community at that time. However, the CPC never entered into force. It was not ratified by enough countries.
Fourteen years later, the **Agreement relating to Community patents** was made at Luxembourg on 15 December 1989. It attempted to revive the CPC project, but also failed. This Agreement consisted of an amended version of the original Community Patent Convention. Twelve states signed the Agreement: Belgium, Denmark, France, Germany, Greece, Ireland, Italy, Luxembourg, the Netherlands, Portugal, Spain, and United Kingdom. All of those states would need to have ratified the Agreement to cause it to enter into force, but only seven did so: Denmark, France, Germany, Greece, Luxembourg, the Netherlands, and United Kingdom.
Nevertheless, a majority of member states of the EEC at that time introduced some harmonisation into their national patent laws in anticipation of the entry in force of the CPC. A more substantive harmonisation took place at around the same time to take account of the European Patent Convention and the Strasbourg Convention.
### 2000 to 2004: EU Regulation proposal {#to_2004_eu_regulation_proposal}
In 2000, renewed efforts from the European Union resulted in a Community Patent Regulation proposal, sometimes abbreviated as **CPR**. It provides that the patent, once it has been granted by the European Patent Office (EPO) in one of its procedural languages (English, German or French) and published in that language, with a translation of the claims into the two other procedural languages, will be valid without any further translation. This proposal is aimed to achieve a considerable reduction in translation costs.
Nevertheless, additional translations could become necessary in legal proceedings against a suspected infringer. In such a situation, a suspected infringer who has been unable to consult the text of the patent in the official language of the Member State in which he is domiciled, is presumed, until proven otherwise, not to have knowingly infringed the patent. To protect a suspected infringer who, in such a situation, has not acted in a deliberate manner, it is provided that the proprietor of the patent will not be able to obtain damages in respect of the period prior to the translation of the patent being notified to the infringer.
The proposed Community Patent Regulation should also establish a court holding exclusive jurisdiction to invalidate issued patents; thus, a Community Patent\'s validity will be the same in all EU member states. This court will be attached to the present European Court of Justice and Court of First Instance through use of provisions in the Treaty of Nice.
Discussion regarding the Community patent had made clear progress in 2003 when a political agreement was reached on 3 March 2003. However, one year later in March 2004 under the Irish presidency, the Competitiveness Council failed to agree on the details of the Regulation. In particular the time delays for translating the claims and the authentic text of the claims in case of an infringement remained problematic issues throughout discussions and in the end proved insoluble.
In view of the difficulties in reaching an agreement on the community patent, other legal agreements have been proposed outside the European Union legal framework to reduce the cost of translation (of patents when granted) and litigation, namely the London Agreement, which entered into force on 1 May 2008---and which has reduced the number of countries requiring translation of European patents granted nowadays under the European Patent Convention, and the corresponding costs to obtain a European patent---and the European Patent Litigation Agreement (EPLA), a proposal that has now lapsed.
#### Reactions to the failure {#reactions_to_the_failure}
After the council in March 2004, EU Commissioner Frits Bolkestein said that \"The failure to agree on the Community Patent I am afraid undermines the credibility of the whole enterprise to make Europe the most competitive economy in the world by 2010.\" Adding:
Jonathan Todd, Commission\'s Internal Market spokesman, declared: `{{blockquote|Normally, after the common political approach, the text of the regulation is agreed very quickly. Instead, some Member States appear to have changed their positions. (...) It is extremely unfortunate that European industry's competitiveness, innovation and R&D are being sacrificed for the sake of preserving narrow vested interests.<ref>{{cite web| url = http://cordis.europa.eu/itt/itt-en/04-3/policy03.htm| title = cordis.europa.eu, ''Patently unclear'', 26 May 2004}}</ref>}}`{=mediawiki}
European Commission President Romano Prodi, asked to evaluate his five-year term, cited as his weak point the failure of many EU governments to implement the \"Lisbon Agenda\", agreed in 2001. In particular, he cited the failure to agree on a Europewide patent, or even the languages to be used for such a patent, \"because member states did not accept a change in the rules; they were not coherent\".
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| 6 |
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# Unitary patent
## Earlier attempts {#earlier_attempts}
### Since 2005: stalemate and new debate {#since_2005_stalemate_and_new_debate}
Thus, in 2005, the Community patent looked unlikely to be implemented in the near future. However, on 16 January 2006 the European Commission \"launched a public consultation on how future action in patent policy to create an EU-wide system of protection can best take account of stakeholders\' needs.\" The Community patent was one of the issues the consultation focused on. More than 2500 replies were received. According to the European Commission, the consultation showed that there is widespread support for the Community patent but not at any cost, and \"in particular not on the basis of the Common Political Approach reached by EU Ministers in 2003\".
In February 2007, EU Commissioner Charlie McCreevy was quoted as saying: `{{blockquote|The proposal for an EU-wide patent is stuck in the mud. It is clear to me from discussions with member states that there is no consensus at present on how to improve the situation.<ref>Chris Jones, [https://web.archive.org/web/20070204044554/http://www.eupolitix.com/EN/News/200702/7be97fa5-3cb6-403f-aadf-103ad99a9950.htm ''McCreevy backs plans for single EU-US market''], TheParliament.com, 1 February 2007. Consulted on 2 February 2007.</ref> }}`{=mediawiki}
The European Commission released a white paper in April 2007 seeking to \"improve the patent system in Europe and revitalise the debate on this issue.\" On 18 April 2007, at the European Patent Forum in Munich, Germany, Günter Verheugen, vice-president of the European Commission, said that his proposal to support the European economy was \"to have the London Agreement ratified by all member states, and to have a European patent judiciary set up, in order to achieve rapid implementation of the Community patent, which is indispensable\". He further said that he believed this could be done within five years.
In October 2007, the Portuguese presidency of the Council of the European Union proposed an EU patent jurisdiction, \"borrowing heavily from the rejected draft European Patent Litigation Agreement (EPLA)\". In November 2007, EU ministers were reported to have made some progress towards a community patent legal system, with \"some specific results\" expected in 2008.
In 2008, the idea of using machine translations to translate patents was proposed to solve the language issue, which is partially responsible for blocking progress on the community patent. Meanwhile, European Commissioner for Enterprise and Industry Günter Verheugen declared at the European Patent Forum in May 2008 that there was an \"urgent need\" for a community patent.
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# Unitary patent
## Earlier attempts {#earlier_attempts}
### Agreement in December 2009, and language issue {#agreement_in_december_2009_and_language_issue}
In December 2009, it was reported that the Swedish EU presidency had achieved a breakthrough in negotiations concerning the community patent. The breakthrough was reported to involve setting up a single patent court for the EU, however ministers conceded much work remained to be done before the community patent would become a reality.
According to the agreed plan, the EU would accede to the European Patent Convention as a contracting state, and patents granted by the European Patent Office will, when validated for the EU, have unitary effect in the territory of the European Union. On 10 November 2010, it was announced that no agreement had been reached and that, \"in spite of the progress made, \[the Competitiveness Council of the European Union had\] fallen short of unanimity by a small margin,\" with commentators reporting that the Spanish representative, citing the aim to avoid any discrimination, had \"re-iterated at length the stubborn rejection of the Madrid Government of taking the \'Munich\' three languages regime (English, German, French) of the European Patent Convention (EPC) as a basis for a future EU Patent
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# Cistron
A **cistron** is a region of DNA that is conceptually equivalent to some definitions of a gene, such that the terms are synonymous from certain viewpoints, especially with regard to the molecular gene as contrasted with the Mendelian gene. The question of which scope of a subset of DNA (that is, how large a segment of DNA) constitutes a unit of selection is the question that governs whether cistrons are the same thing as genes . The word *cistron* is used to emphasize that molecular genes exhibit a specific behavior in a complementation test (cis-trans test); distinct positions (or loci) within a genome are **cistronic**.
## History
The words *cistron* and *gene* were coined before the advancing state of biology made it clear to many people that the concepts they refer to, at least in some senses of the word *gene*, are either equivalent or nearly so. The same historical naming practices are responsible for many of the synonyms in the life sciences.
The term *cistron* was coined by Seymour Benzer in an article entitled *The elementary units of heredity*. The cistron was defined by an operational test applicable to most organisms that is sometimes referred to as a cis-trans test, but more often as a complementation test.
Richard Dawkins in his influential book *The Selfish Gene* argues *against* the cistron being the unit of selection and against it being the best definition of a gene. (He also argues against group selection.) He does not argue against the existence of cistrons, or their being elementary, but rather against the idea that natural selection selects them; he argues that it used to, back in earlier eras of life\'s development, but not anymore. He defines a gene as a larger unit, which others may now call gene clusters, as the unit of selection. He also defines replicators, more general than cistrons and genes, in this gene-centered view of evolution.
## Definition
Defining a Cistron as a segment of DNA coding for a polypeptide, the structural gene in a transcription unit could be said as monocistronic (mostly in eukaryotes) or polycistronic (mostly in bacteria and prokaryotes). For example, suppose a mutation at a chromosome position $x$ is responsible for a change in recessive trait in a diploid organism (where chromosomes come in pairs). We say that the mutation is recessive because the organism will exhibit the wild type phenotype (ordinary trait) unless both chromosomes of a pair have the mutation (homozygous mutation). Similarly, suppose a mutation at another position, $y$, is responsible for the same recessive trait. The positions $x$ and $y$ are said to be within the same cistron when an organism that has the mutation at $x$ on one chromosome and has the mutation at position $y$ on the paired chromosome exhibits the recessive trait even though the organism is not homozygous for either mutation. When instead the wild type trait is expressed, the positions are said to belong to distinct cistrons / genes. Or simply put, mutations on the same cistrons will not complement; as opposed to mutations on different cistrons may complement (see Benzer\'s T4 bacteriophage experiments T4 rII system).
For example, an operon is a stretch of DNA that is transcribed to create a contiguous segment of RNA, but contains more than one cistron / gene. The operon is said to be polycistronic, whereas ordinary genes are said to be monocistronic
| 565 |
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| 0 |
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# Commodore 1541
The **Commodore 1541** (also known as the **CBM 1541** and **VIC-1541**) is a floppy disk drive which was made by Commodore International for the Commodore 64 (C64), Commodore\'s most popular home computer. The best-known floppy disk drive for the C64, the 1541 is a single-sided 170-kilobyte drive for 5¼\" disks. The 1541 directly followed the Commodore 1540 (meant for the VIC-20).
The disk drive uses group coded recording (GCR) and contains a MOS Technology 6502 microprocessor, doubling as a disk controller and on-board disk operating system processor. The number of sectors per track varies from 17 to 21 (an early implementation of zone bit recording with 4 constant angular velocity zones). The drive\'s built-in disk operating system is CBM DOS 2.6.
## History
### Introduction
The 1541 was priced at under `{{US$|400}}`{=mediawiki} at its introduction. A C64 with a 1541 cost about \$900, while an Apple II with no disk drive cost \$1,295. The first 1541 drives produced in 1982 have a label on the front reading VIC-1541 and an off-white case to match the VIC-20. In 1983, the 1541 switched to the familiar beige case and a front label reading simply \"1541\" along with rainbow stripes to match the Commodore 64.
By 1983, a 1541 sold for \$300 or less. After a home computer price war instigated by Commodore, the C64 and 1541 together cost under \$500. The drive became very popular and difficult to find. The company said that the shortage occurred because 90% of C64 owners bought the 1541 compared to its 30% expectation, but the press discussed what *Creative Computing* described as \"an absolutely alarming return rate\" because of defects. The magazine reported in March 1984 that it received three defective drives in two weeks, and *Compute!\'s Gazette* reported in December 1983 that four of the magazine\'s seven drives had failed; \"COMPUTE! Publications sorely needs additional 1541s for in-house use, yet we can\'t find any to buy. After numerous phone calls over several days, we were able to locate only two units in the entire continental United States\", reportedly because of Commodore\'s attempt to resolve a manufacturing issue that caused the high failures.
The early (1982 to 1983) 1541s have a spring-eject mechanism (Alps drive), and the disks often fail to release. This style of drive has the popular nickname \"Toaster Drive\", because it requires the use of a knife or other hard thin object to pry out the stuck media, just like a piece of toast stuck in an actual toaster. This was fixed later when Commodore changed the vendor of the drive mechanism (Mitsumi) and adopted the flip-lever Newtronics mechanism, greatly improving reliability. In addition, Commodore made the drive\'s controller board smaller and reduced its chip count compared to the early 1541s (which had a large PCB running the length of the case, with dozens of TTL chips). The beige-case Newtronics 1541 was produced from 1984 to 1986.
### Versions and third-party clones {#versions_and_third_party_clones}
All but the very earliest non-II model 1541s can use either the Alps or Newtronics mechanism. Visually, the first models, of the *VIC-1541* denomination, have an off-white color like the VIC-20 and VIC-1540. Then, to match the look of the C64, CBM changed the drive\'s color to brown-beige and the name to *Commodore 1541*.
The 1541\'s numerous shortcomings opened a market for a number of third-party clones of the disk drive. Examples include the *Oceanic OC-118* a.k.a. *Excelerator+*, the MSD Super Disk single and dual drives, the *Enhancer 2000*, the *Indus GT*, Blue Chip Electronics\'s BCD/5.25, and *CMD*{{\'}}s *FD-2000* and *FD-4000*. Nevertheless, the 1541 became the first disk drive to see widespread use in the home and Commodore sold millions of the units.
In 1986, Commodore released the 1541C, a revised version that offers quieter and slightly more reliable operation and a light beige case matching the color scheme of the Commodore 64C. It was replaced in 1988 by the 1541-II, which uses an external power supply to provide cooler operation and allows the drive to have a smaller desktop footprint (the power supply \"brick\" being placed elsewhere, typically on the floor). Later ROM revisions fixed assorted problems, including a software bug that causes the save-and-replace command to corrupt data.
### Successors
The Commodore 1570 is an upgrade from the 1541 for use with the Commodore 128, available in Europe. It offers MFM capability for accessing CP/M disks, improved speed, and somewhat quieter operation, but was only manufactured until Commodore got its production lines going with the 1571, the double-sided drive. Finally, the small, external-power-supply-based, MFM-based Commodore 1581 3½-inch drive was made, giving 800 KB access to the C128 and C64.
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| 0 |
6,767 |
# Commodore 1541
## Design
### Hardware
The 1541 does not have DIP switches to change the device number. If a user adds more than one drive to a system, the user has to cut a trace in the circuit board to permanently change the drive\'s device number, or hand-wire an external switch to allow it to be changed externally. It is also possible to change the drive number via a software command, which is temporary and would be erased as soon as the drive was powered off.
1541 drives at power up always default to device #8. If multiple drives in a chain are used, then the startup procedure is to power on the first drive in the chain, alter its device number via a software command to the highest number in the chain (if three drives were used, then the first drive in the chain would be set to device #10), then power on the next drive, alter its device number to the next lowest, and repeat the procedure until the final drive at the end of the chain was powered on and left as device #8.
Unlike the Apple II, where support for two drives is normal, it is relatively uncommon for Commodore software to support this setup, and the CBM DOS copy file command is not able to copy files between drives -- a third party copy utility is necessary.
The pre-II 1541s also have an internal power source, which generates a lot of heat. The heat generation was a frequent source of humour. For example, *Compute!* stated in 1988 that \"Commodore 64s used to be a favorite with amateur and professional chefs since they could compute and cook on top of their 1500-series disk drives at the same time\". A series of humorous tips in *MikroBitti* in 1989 said \"When programming late, coffee and kebab keep nicely warm on top of the 1541.\" The *MikroBitti* review of the 1541-II said that its external power source \"should end the jokes about toasters\".
The drive-head mechanism installed in the early production years is notoriously easy to misalign. The most common cause of the 1541\'s drive head knocking and subsequent misalignment is copy-protection schemes on commercial software.`{{r|info19860506}}`{=mediawiki} The main cause of the problem is that the disk drive itself does not feature any means of detecting when the read/write head reaches track zero. Accordingly, when a disk is not formatted or a disk error occurs, the unit tries to move the head 40 times in the direction of track zero (although the 1541 DOS only uses 35 tracks, the drive mechanism itself is a 40-track unit, so this ensured track zero would be reached no matter where the head was before). Once track zero is reached, every further attempt to move the head in that direction would cause it to be rammed against a solid stop: for example, if the head happened to be on track 18 (where the directory is located) before this procedure, the head would be actually moved 18 times, and then rammed against the stop 22 times. This ramming gives the characteristic \"machine gun\" noise and sooner or later throws the head out of alignment.
A defective head-alignment part likely caused many of the reliability issues in early 1541 drives; one dealer told *Compute!{{\'}}s Gazette* in 1983 that the part had caused all but three of several hundred drive failures that he had repaired.`{{r|halfhill198312}}`{=mediawiki} The drives were so unreliable that *Info* magazine joked, \"Sometimes it seems as if one of the original design specs \... must have said \'Mean time between failure: 10 accesses.\'\" Users can realign the drive themselves with a software program and a calibration disk. The user can remove the drive from its case and then loosen the screws holding the stepper motor that move the head, then with the calibration disk in the drive gently turn the stepper motor back and forth until the program shows a good alignment. The screws are then tightened and the drive is put back into its case.
A third-party fix for the 1541 appeared in which the solid head stop was replaced by a sprung stop, giving the head a much easier life.`{{r|info19860506}}`{=mediawiki} The later 1571 drive (which is 1541-compatible) incorporates track-zero detection by photo-interrupter and is thus immune to the problem. Also, a software solution, which resides in the drive controller\'s ROM, prevents the rereads from occurring, though this can cause problems when genuine errors do occur.
Due to the alignment issues on the Alps drive mechanisms, Commodore switched suppliers to Newtronics in 1984. The Newtronics mechanism drives have a lever rather than a pull-down tab to close the drive door. Although the alignment issues were resolved after the switch, the Newtronics drives add a new reliability problem in that many of the read/write heads are improperly sealed, causing moisture to penetrate the head and short it out.
The 1541\'s PCB consists mainly of a 6502 CPU, two 6522 VIA chips, and 2 KB of work RAM. Up to 48 KB of RAM can be added; this is mainly useful for defeating copy protection schemes since an entire disk track could be loaded into drive RAM, while the standard 2 KB only accommodates a few sectors (theoretically eight, but some of the RAM was used by CBM DOS as work space). Some Commodore users use 1541s as an impromptu math coprocessor by uploading math-intensive code to the drive for background processing.
### Interface
The 1541 uses a proprietary serialized derivative of the IEEE-488 parallel interface, found in previous disk drives for the PET/CBM range of personal and business computers, but when the VIC-20 was in development, a cheaper alternative to the expensive IEEE-488 cables was sought. To ensure a ready supply of inexpensive cabling for its home computer peripherals, Commodore chose standard DIN connectors for the serial interface. Disk drives and other peripherals such as printers connect to the computer via a daisy chain setup, necessitating only a single connector on the computer itself.
| 1,001 |
Commodore 1541
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# Commodore 1541
## Design
### Control
| 7 |
Commodore 1541
| 2 |
6,767 |
# Commodore 1541
## Throughput and software {#throughput_and_software}
*IEEE Spectrum* in 1985 stated that:
The C-64\'s designers blamed the 1541\'s slow speed on the marketing department\'s insistence that the computer be compatible with the 1540, which is slow because of a flaw in the 6522 VIA interface controller.`{{r|ieee85}}`{=mediawiki} Initially, Commodore intended to use a hardware shift register (one component of the 6522) to maintain fast drive speeds with the new serial interface. However, a hardware bug with this chip prevents the initial design from working as anticipated, and the ROM code was hastily rewritten to handle the entire operation in software. According to Jim Butterfield, this causes a speed reduction by a factor of five; had 1540 compatibility not been a requirement, the disk interface would have been much faster. In any case, the C64 normally cannot work with a 1540 unless the VIC-II display output is disabled via a register write to the DEN bit (register \$D011, bit 4), which stops the halting of the CPU during certain video lines to ensure correct serial timing.
As implemented on the VIC-20 and C64, Commodore DOS transfers 512 bytes per second, compared to the Atari 810\'s 1,000 bytes per second, the Apple Disk II\'s 15,000 bytes per second,`{{r|ieee85}}`{=mediawiki} and the 300-baud data rate of the Commodore Datasette storage system. About 20 minutes are needed to copy one disk---10 minutes of reading time, and 10 minutes of writing time. However, since both the computer and the drive can easily be reprogrammed, third parties quickly wrote more efficient firmware that would speed up drive operations drastically. Without hardware modifications, some \"fast loader\" utilities (which bypassed routines in the 1541\'s onboard ROM) managed to achieve speeds of up to 2.5 kilobytes per second.`{{r|ieee85}}`{=mediawiki} The most common of these products are the Epyx Fast Load, the Final Cartridge, and the Action Replay plug-in ROM cartridges, which all have machine code monitor and disk editor software on board as well. The popular Commodore computer magazines of the era also entered the arena with type-in fast-load utilities, with *Compute!\'s Gazette* publishing *TurboDisk* in 1985 and *RUN* publishing *Sizzle* in 1987.
Even though each 1541 has its own on-board disk controller and disk operating system, it is not possible for a user to command two 1541 drives to copy a disk (one drive reading and the other writing) as with older dual drives like the 4040 that was often found with the PET computer, and which the 1541 is backward-compatible with (it can read 4040 disks but not write to them as a minor difference in the number of header bytes makes the 4040 and 1541 only read-compatible). Originally, to copy from drive to drive, software running on the C64 was needed and it would first read from one drive into computer memory, then write out to the other. Only when Fast Hack\'em and, later, other disk backup programs were released, was true drive-to-drive copying possible for a pair of 1541s. The user could, if they wished, unplug the C64 from the drives (i.e., from the first drive in the daisy chain) and do something else with the computer as the drives proceeded to copy the entire disk.
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# Commodore 1541
## Media
The 1541 drive uses standard 5¼-inch double-density floppy media; high-density media will not work due to its different magnetic coating requiring a higher magnetic coercivity. As the GCR encoding scheme does not use the index hole, the drive was also compatible with hard-sectored disks. The standard CBM DOS format is 170 KB with 35 tracks and 256-byte sectors. It is similar to the format used on the PET 2031, 2040 & 4040 drives, but a minor difference in the number of header bytes makes these drives and the 1541 only read-compatible; disks formatted with one drive cannot be written to by the other. The drives will allow writes to occur, but the inconsistent header size will damage the data in the data portions of each track.
The 4040 drives use Shugart SA-400s, which were 35-track units, thus the format there is due to physical limitations of the drive mechanism. The 1541 uses 40-track mechanisms, but Commodore intentionally limited the CBM DOS format to 35 tracks because of reliability issues with the early units. It is possible via low-level programming to move the drive head to tracks 36--40 and write on them, this is sometimes done by commercial software for copy protection purposes and/or to get additional data on the disk.
However, one track is reserved by DOS for directory and file allocation information (the BAM, block availability map). And since for normal files, two bytes of each physical sector are used by DOS as a pointer to the next physical track and sector of the file, only 254 out of the 256 bytes of a block are used for file contents.
If the disk side is not otherwise prepared with a custom format, (e.g. for data disks), 664 blocks would be free after formatting, giving 664`{{resx}}`{=mediawiki}254 = `{{val|168656|ul=bytes|fmt=commas}}`{=mediawiki} (or almost `{{val|165|u=KB}}`{=mediawiki}) for user data.
By using custom formatting and load/save routines (sometimes included in third-party DOSes, see below), all of the mechanically possible 40 tracks can be used.
Owing to the drive\'s non-use of the index hole, it is also possible to make \"flippy floppies\" by inserting the diskette upside-down and formatting the other side, and it is commonplace and normal for commercial software to be distributed on such disks.
+--------+-------------+------------------------+
| Tracks | Sectors\ | bits/s |
| | (256 bytes) | |
+========+=============+========================+
| 1--17 | 21 | 16M/4/(13+0) = 307,692 |
+--------+-------------+------------------------+
| 18--24 | 19 | 16M/4/(13+1) = 285,714 |
+--------+-------------+------------------------+
| 25--30 | 18 | 16M/4/(13+2) = 266,667 |
+--------+-------------+------------------------+
| 31--35 | 17 | 16M/4/(13+3) = 250,000 |
+--------+-------------+------------------------+
| 36--42 | 17 | 16M/4/(13+3) = 250,000 |
+--------+-------------+------------------------+
Tracks 36--42 are non-standard. The bitrate is the raw one between the read/write head and signal circuitry so actual useful data rate is a factor 5/4 less due to GCR encoding.
The 1541 disk typically has 35 tracks. Track 18 is reserved; the remaining tracks are available for data storage. The header is on 18/0 (track 18, sector 0) along with the BAM, and the directory starts on 18/1 (track 18, sector 1). The file interleave is 10 blocks, while the directory interleave is 3 blocks.
Header contents: The header is similar to other Commodore disk headers, the structural differences being the BAM offset (`{{mono|$04}}`{=mediawiki}) and size, and the label+ID+type offset (`{{mono|$90}}`{=mediawiki}).
`$00–01 T/S reference to first directory sector (18/1)`\
` 02 DOS version ('A')`\
` 04–8F BAM entries (4 bytes per track: Free Sector Count + 24 bits for sectors)`\
` 90–9F Disk Label, $A0 padded`\
` A2–A3 Disk ID`\
` A5–A6 DOS type ('2A')`
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Commodore 1541
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# Commodore 1541
## Uses
Early copy protection schemes deliberately introduce read errors on the disk, the software refusing to load unless the correct error message is returned. The general idea is that simple disk-copy programs are incapable of copying the errors. When one of these errors is encountered, the disk drive (as do many floppy disk drives) will attempt one or more reread attempts after first resetting the head to track zero. Few of these schemes have much deterrent effect, as various software companies soon released \"nibbler\" utilities that enable protected disks to be copied and, in some cases, the protection removed.
Commodore copy protection sometimes fails on specific hardware configurations. *Gunship*, for example, does not load if a second disk drive or printer is connected to the computer. Similarly *Roland\'s Ratrace* will crash if additional hardware is detected. The tape version will even crash if a floppy drive is switched on while the game is running
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# Commodore 1581
\| discontinued = 1990`{{r|w81}}`{=mediawiki} \| media = 3½\" floppy disk DS`{{r|w81}}`{=mediawiki}`{{r|1987_1581UsersGuide|page=125}}`{=mediawiki} DD using MFM \| os = CBM DOS 10.0 \| power = 10 W (220 V at 50 Hz) \| cpu = MOS 6502 @ `{{nowrap|2 MHz}}`{=mediawiki} , WD1770 or WD1772 \| memory = 8 KB RAM, 32 KB ROM`{{r|w81}}`{=mediawiki}`{{r|1987_1581UsersGuide|page=125}}`{=mediawiki} \| storage = 790 KB`{{r|1987_1581UsersGuide|page=125}}`{=mediawiki} \|connectivity = Commodore proprietary serial IEEE-488 burst mode `{{nowrap|9000 bytes/s}}`{=mediawiki} \| dimensions = 63 x`{{r|1987_1581UsersGuide|page=125}}`{=mediawiki} \| weight = 1.4 kg`{{r|1987_1581UsersGuide|page=125}}`{=mediawiki}`{{r|arc81}}`{=mediawiki} \| compatibility= `{{hlist|[[Commodore 128]]{{r|1987_1581UsersGuide|page=1}}|[[Commodore 64]]{{r|1987_1581UsersGuide|page=1}}|[[Commodore Plus/4]]{{r|1987_1581UsersGuide|page=1}}|[[Commodore 16]]{{r|1987_1581UsersGuide|page=1}}|[[VIC-20]]{{r|1987_1581UsersGuide|page=1}}}}`{=mediawiki} \| predecessor = Commodore 1571 \| successor = \| related = }}
The **Commodore 1581** is a 3½-inch double-sided double-density floppy disk drive that was released by Commodore Business Machines (CBM) in 1987, primarily for its C64 and C128 home/personal computers. The drive stores 800 kilobytes using an MFM encoding but formats different from the MS-DOS (720 KB), Amiga (880 KB), and Mac Plus (800 KB) formats. With special software it\'s possible to read C1581 disks on an x86 PC system, and likewise, read MS-DOS and other formats of disks in the C1581 (using Big Blue Reader), provided that the PC or other floppy handles the `{{nowrap|"720 KB"}}`{=mediawiki} size format. This capability was most frequently used to read MS-DOS disks. The drive was released in the summer of 1987 and quickly became popular with bulletin board system (BBS) operators and other users.
Like the 1541 and 1571, the 1581 has an onboard MOS Technology 6502 CPU with its own ROM and RAM, and uses a serial version of the IEEE-488 interface. Inexplicably, the drive\'s ROM contains commands for parallel use, although no parallel interface was available. Unlike the 1571, which is nearly 100% backward-compatible with the 1541, the 1581 is only compatible with previous Commodore drives at the DOS level and cannot utilize software that performs low-level disk access (as the vast majority of Commodore 64 games do).
The version of Commodore DOS built into the 1581 added support for partitions, which could also function as fixed-allocation subdirectories. PC-style subdirectories were rejected as being too difficult to work with in terms of block availability maps, which were still very much in vogue, and which for some time had been the traditional way of inquiring into block availability. The 1581 supports the C128\'s burst mode for fast disk access, but not when connected to an older Commodore machine like the Commodore 64. The 1581 provides a total of 3160 blocks free when formatted (a block being equal to 256 bytes). The number of permitted directory entries was also increased, to 296 entries. With a storage capacity of 800 KB, the 1581 is the highest-capacity serial-bus drive that was ever made by Commodore (the 1-MB SFD-1001 uses the parallel IEEE-488), and the only 3½-inch one. However, starting in 1991, Creative Micro Designs (CMD) made the FD-2000 high density (1.6 MB) and FD-4000 extra-high density (3.2 MB) 3½-inch drives, both of which offered not only a 1581-emulation mode but also 1541- and 1571-compatibility modes.
Like the 1541 and 1571, a nearly identical job queue is available to the user in zero page (except for job 0), providing for exceptional degrees of compatibility.
Unlike the cases of the 1541 and 1571, the low-level disk format used by the 1581 is similar enough to the MS-DOS format as the 1581 is built around a WD1770 FM/MFM floppy controller chip. The 1581 disk format consists of 80 tracks and ten 512 byte sectors per track, per side, used as 40 logical sectors of 256 bytes each . Special software is required to read 1581 disks on a PC due to the different file system. An internal floppy drive and controller are required as well; USB floppy drives operate strictly at the file system level and do not allow low-level disk access. The WD1770 controller chip, however, was the seat of some early problems with 1581 drives when the first production runs were recalled due to a high failure rate; the problem was quickly corrected. Later versions of the 1581 drive have a smaller, more streamlined-looking external power supply provided with them.
## Specifications
+---------------------------+----------------------------------------------------------------------------------------------------------------+
| Quantity | Value |
+===========================+================================================================================================================+
| Onboard CPU | MOS Technology 6502 @ 2 MHz |
+---------------------------+----------------------------------------------------------------------------------------------------------------+
| RAM | 8 KB`{{r|z81sv02|page=2}}`{=mediawiki} |
+---------------------------+----------------------------------------------------------------------------------------------------------------+
| ROM | 32 KB`{{r|z81sv02|page=2}}`{=mediawiki} |
+---------------------------+----------------------------------------------------------------------------------------------------------------+
| Disk controller | WD1770`{{r|w81}}`{=mediawiki}`{{r|z81sv02|page=2, 12}}`{=mediawiki} or WD1772`{{r|1987_LtKernal}}`{=mediawiki} |
+---------------------------+----------------------------------------------------------------------------------------------------------------+
| Communications controller | MOS Technology 8520A |
+---------------------------+----------------------------------------------------------------------------------------------------------------+
| Transfer protocols | Standard and fast serial; burst mode; and commands for parallel interface (the latter not used) |
+---------------------------+----------------------------------------------------------------------------------------------------------------+
| Disk type | 3.5-inch |
+---------------------------+----------------------------------------------------------------------------------------------------------------+
| Storage format | MFM, double density, double-sided |
+---------------------------+----------------------------------------------------------------------------------------------------------------+
| Interface | CBM\'s proprietary serial IEEE-488 |
+---------------------------+----------------------------------------------------------------------------------------------------------------+
| Power | `{{nowrap|(5 [[Volt-ampere|VA]])}}`{=mediawiki}\ |
| | `{{nowrap|12 V @ 0.5 A}}`{=mediawiki} `{{nowrap|(6 VA)}}`{=mediawiki} |
+---------------------------+----------------------------------------------------------------------------------------------------------------+
### 1581 Image Layout {#image_layout}
The 1581 disk has 80 logical tracks, each with 40 logical sectors (the actual physical layout of the diskette is abstracted and managed by a hardware translation layer). The directory starts on 40/3 (track 40, sector 3). The disk header is on 40/0, and the BAM (block availability map) resides on 40/1 and 40/2
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Commodore 1581
| 0 |
6,774 |
# Consubstantiation
**Consubstantiation** is a Christian theological doctrine that (like transubstantiation) describes the real presence of Christ in the Eucharist. It holds that during the sacrament, the substance of the body and blood of Christ are present alongside the substance of the bread and wine, which remain present. It was part of the doctrines of Lollardy, and considered a heresy by the Roman Catholic Church. It was later championed by Edward Pusey of the Oxford Movement, and is therefore held by many high church Anglicans, seemingly contrary to the Black Rubric of the Book of Common Prayer. The Irvingian Churches (such as the New Apostolic Church) adhere to consubstantiation as the explanation of the real presence of Christ in the Eucharist.
## Development
In England in the late 14th century, there was a political and religious movement known as Lollardy. Among much broader goals, the Lollards affirmed a form of consubstantiation---that the Eucharist remained physically bread and wine, while becoming spiritually the body and blood of Christ. Lollardy survived up until the time of the English Reformation.
Whilst ultimately rejected by him on account of the authority of the Church of Rome, William of Ockham entertains a version of consubstantiation in his *Fourth Quodlibet, Question 30*, where he claims that \"the substance of the bread and the substance of the wine remain there and that the substance of the body of Christ remains in the same place, together with the substance of the bread\".
Literary critic Kenneth Burke\'s dramatism takes this concept and utilizes it in secular rhetorical theory to look at the dialectic of unity and difference within the context of logology.
The doctrine of consubstantiation is often held in contrast to the doctrine of transubstantiation.
To explain the manner of Christ\'s presence in Holy Communion, many high church Anglicans teach the philosophical explanation of consubstantiation. A major leader in the Anglo-Catholic Oxford Movement, Edward Pusey, championed the view of consubstantiation. Pusey\'s view is that: `{{blockquote|I cannot deem it unfair to apply the name of Consubstantiation to a doctrine which teaches, that "the true flesh and true blood of Christ are in the true bread and wine", in such a way that "whatsoever motion or action the bread" and wine have, the body and blood "of Christ also" have "the same"; and that "the substances in both cases" are "so mingled—that they should constitute some one thing".<ref name="Vogan1871">{{cite book|last=Vogan|first=Thomas Stuart Lyle|title=The True Doctrine of the Eucharist|year=1871|publisher=Longmans, Green|language=en |page=54}}</ref>}}`{=mediawiki}
The Irvingian Churches adhere to the doctrine of consubstantiation; for example, *The Catechism of the New Apostolic Church* states:
The term *consubstantiation* has been used to describe Martin Luther\'s Eucharistic doctrine, the sacramental union. Lutheran theologians reject the term because it refers to a philosophical construct that they believe differs from the Lutheran doctrine of the sacramental union, denotes a mixing of substances (bread and wine with body and blood), and suggests a \"gross, Capernaitic, carnal\" presence of the body and blood of Christ
| 493 |
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# Congregational polity
**Congregational polity**, or **congregationalist polity**, often known as **congregationalism**, is a system of ecclesiastical polity in which every local church (congregation) is independent, ecclesiastically sovereign, or \"autonomous\". Its first articulation in writing is the Cambridge Platform of 1648 in New England.
Major Protestant Christian traditions that employ congregationalism include Baptist churches, the Congregational Methodist Church, and Congregational churches known by the *Congregationalist* name and having descended from the Independent Reformed wing of the Anglo-American Puritan movement of the 17th century. More recent generations have witnessed a growing number of nondenominational churches, which are often congregationalist in their governance. Although autonomous, like minded congregations may enter into voluntary associations with other congregations, sometimes called conventions, denominations, or associations.
Congregationalism is distinguished from episcopal polity which is governance by a hierarchy of bishops, and is also distinct from presbyterian polity in which higher assemblies of congregational representatives can exercise considerable authority over individual congregations.
Congregationalism is not limited only to organization of Christian church congregations. The principles of congregationalism have been inherited by the Unitarian Universalist Association and the Canadian Unitarian Council.
## Basic form {#basic_form}
The term *congregational polity* describes a form of church governance that is based on the local congregation. Each local congregation is independent and self-supporting, governed by its own members. Some band into loose voluntary associations with other congregations that share similar beliefs (e.g., the Willow Creek Association and the Unitarian Universalist Association). Others join \"conventions\", such as the Southern Baptist Convention, the National Baptist Convention or the American Baptist Churches USA (formerly the Northern Baptist Convention). These conventions generally provide stronger ties between congregations, including some doctrinal direction and pooling of financial resources. Congregations that belong to associations and conventions are still independently governed. Most non-denominational churches are organized along congregationalist lines. Many do not see these voluntary associations as \"denominations\", because they \"believe that there is no church other than the local church, and denominations are in variance to Scripture.\"
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# Congregational polity
## Denominational families {#denominational_families}
These Christian traditions use forms of congregational polity.
### Congregational churches {#congregational_churches}
Congregationalism is a Protestant tradition with roots in the Puritan and Independent movements. In congregational government, the covenanted congregation exists prior to its officers, and as such the members are equipped to call and dismiss their ministers without oversight from any higher ecclesiastical body. Their churches ordinarily have at least one pastor, but may also install ruling elders.
Statements of polity in the congregational tradition called \"platforms\". These include the Savoy Confession\'s platform, the Cambridge Platform, and the Saybrook Platform. Denominations in the congregational tradition include the UCC, NACCC, CCCC, and EFCC. Denominations in the tradition support but do not govern their constituent members.
### Baptist churches {#baptist_churches}
Most Baptists hold that no denominational or ecclesiastical organization has inherent authority over an individual Baptist church. Churches can properly relate to each other under this polity only through voluntary cooperation, never by any sort of coercion. Furthermore, this Baptist polity calls for freedom from governmental control. Exceptions to this local form of local governance include the Episcopal Baptists that have an episcopal system.
Independent Baptist churches have no formal organizational structure above the level of the local congregation. More generally among Baptists, a variety of parachurch agencies and evangelical educational institutions may be supported generously or not at all, depending entirely upon the local congregation\'s customs and predilections. Usually doctrinal conformity is held as a first consideration when a church makes a decision to grant or decline financial contributions to such agencies, which are legally external and separate from the congregations they serve. These practices also find currency among non-denominational fundamentalist or charismatic fellowships, many of which derive from Baptist origins, culturally if not theologically.
Most Southern Baptist and National Baptist congregations, by contrast, generally relate more closely to external groups such as mission agencies and educational institutions than do those of independent persuasion. However, they adhere to a very similar ecclesiology, refusing to permit outside control or oversight of the affairs of the local church.
### Churches of Christ {#churches_of_christ}
Ecclesiastical government is congregational rather than denominational. Churches of Christ purposefully have no central headquarters, councils, or other organizational structure above the local church level. Rather, the independent congregations are a network with each congregation participating at its own discretion in various means of service and fellowship with other congregations. Churches of Christ are linked by their shared commitment to restoration principles.
Congregations are generally overseen by a plurality of elders (also known in some congregations as shepherds, bishops, or pastors) who are sometimes assisted in the administration of various works by deacons. Elders are generally seen as responsible for the spiritual welfare of the congregation, while deacons are seen as responsible for the non-spiritual needs of the church. Deacons serve under the supervision of the elders, and are often assigned to direct specific ministries. Successful service as a deacon is often seen as preparation for the eldership. Elders and deacons are chosen by the congregation based on the qualifications found in Timothy 3 and Titus 1. Congregations look for elders who have a mature enough understanding of scripture to enable them to supervise the minister and to teach, as well as to perform governance functions. In lieu of willing men who meet these qualifications, congregations are sometimes overseen by an unelected committee of the congregation\'s men.
While the early Restoration Movement had a tradition of itinerant preachers rather than \"located Preachers\", during the 20th century a long-term, formally trained congregational minister became the norm among Churches of Christ. Ministers are understood to serve under the oversight of the elders. While the presence of a long-term professional minister has sometimes created \"significant *de facto* ministerial authority\" and led to conflict between the minister and the elders, the eldership has remained the \"ultimate locus of authority in the congregation\". There is a small group within the Churches of Christ which oppose a single preacher and, instead, rotate preaching duties among qualified elders (this group tends to overlap with groups which oppose Sunday School and also have only one cup to serve the Lord\'s Supper).
Churches of Christ hold to the priesthood of all believers. No special titles are used for preachers or ministers that would identify them as clergy. Churches of Christ emphasize that there is no distinction between \"clergy\" and \"laity\" and that every member has a gift and a role to play in accomplishing the work of the church.
### Congregational Methodist Church {#congregational_methodist_church}
Methodists who disagreed with the episcopal polity of the Methodist Episcopal Church, South left their mother church to form the Congregational Methodist Church, which retains Wesleyan-Arminian theology but adopts congregationalist polity as a distinctive
| 788 |
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# Reaction kinetics in uniform supersonic flow
**Reaction kinetics in uniform supersonic flow** (*\'\'\'Cinétique de Réaction en Ecoulement Supersonique Uniforme\'\'\'*, **CRESU**) is an experiment investigating chemical reactions taking place at very low temperatures.
The technique involves the expansion of a gas or mixture of gases through a de Laval nozzle from a high-pressure reservoir into a vacuum chamber. As it expands, the nozzle collimates the gas into a uniform supersonic beam, which is essentially collision-free and has a temperature that, in the centre-of-mass frame, can be significantly below that of the reservoir gas. Each nozzle produces a characteristic temperature. This way, any temperature between room temperature and about 10 K can be achieved.
## Apparatus
There are relatively few CRESU apparatuses in existence for the simple reason that the gas throughput and pumping requirements are huge, which makes them expensive to run. Two of the leading centres have been the University of Rennes (France) and the University of Birmingham (UK). A more recent development has been a pulsed version of the CRESU, which requires far less gas and therefore smaller pumps.
## Kinetics
Most species have a negligible vapour pressure at such low temperatures, and this means that they quickly condense on the sides of the apparatus. Essentially, the CRESU technique provides a \"wall-less flow tube\", which allows the kinetics of gas-phase reactions to be investigated at much lower temperatures than otherwise possible.
Chemical kinetics experiments can then be carried out in a pump--probe fashion, using a laser to initiate the reaction (for example, by preparing one of the reagents by photolysis of a precursor), followed by observation of that same species (for example, by laser-induced fluorescence) after a known time delay. The fluorescence signal is captured by a photomultiplier a known distance downstream of the de Laval nozzle. The time delay can be varied up to the maximum corresponding to the flow time over that known distance. By studying how quickly the reagent species disappears in the presence of differing concentrations of a (usually stable) co-reagent species, the reaction rate constant at the low temperature of the CRESU flow can be determined.
Reactions studied by the CRESU technique typically have no significant activation energy barrier. In the case of neutral--neutral reactions (i.e., not involving any charged species, ions), these types of barrier-free reactions usually involve free radical species, such as molecular oxygen (O~2~), the cyanide radical (CN) or the hydroxyl radical (OH). The energetic driving force for these reactions is typically an attractive long-range intermolecular potential.
CRESU experiments have been used to show deviations from Arrhenius kinetics at low temperatures: as the temperature is reduced, the rate constant actually increases. They can explain why chemistry is so prevalent in the interstellar medium, where many different polyatomic species have been detected (by radio astronomy)
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# Corinth
**Corinth** (`{{IPAc-en|ˈ|k|ɒr|ɪ|n|θ}}`{=mediawiki} `{{respell|KORR|inth}}`{=mediawiki}; *Kórinthos*, `{{IPA|el|ˈkorinθos|label=[[Modern Greek]] pronunciation:|Ell-Korinthos.ogg}}`{=mediawiki}) is a municipality in Corinthia in Greece. The successor to the ancient city of Corinth, it is a former municipality in Corinthia, Peloponnese, which is located in south-central Greece. Since the 2011 local government reform, it has been part of the municipality of Corinth, of which it is the seat and a municipal unit. It is the capital of Corinthia.
It was founded as **Nea Korinthos** (*Νέα Κόρινθος*), or **New Corinth**, in 1858 after an earthquake destroyed the existing settlement of Corinth, which had developed in and around the site of the ancient city.
## History
Corinth derives its name from Ancient Corinth, a city-state of antiquity. The site was occupied from before 3000 BC.
### Ancient Greece {#ancient_greece}
Historical references begin with the early 8th century BC, when ancient Corinth began to develop as a commercial center. Between the 8th and 7th centuries, the Bacchiad family ruled Corinth. Cypselus overthrew the Bacchiad family, and between 657 and 585 BC, he and his son Periander ruled Corinth as the Tyrants.
In about 585 BC, an oligarchical government seized power. This government later allied with Sparta within the Peloponnesian League, and Corinth participated in the Persian Wars and Peloponnesian War as an ally of Sparta. After Sparta\'s victory in the Peloponnesian war, the two allies fell out with one another, and Corinth pursued an independent policy in the various wars of the early 4th century BC. After the Macedonian conquest of Greece, the Acrocorinth was the seat of a Macedonian garrison until 243 BC, when the city joined the Achaean League.
### Ancient Rome {#ancient_rome}
Nearly a century later, in 146 BC, Corinth was captured and was completely destroyed by the Roman army.
As a newly rebuilt Roman colony in 44 BC, Corinth flourished and became the administrative capital of the Roman province of Achaea.
### Medieval times {#medieval_times}
A major earthquake struck Corinth and its region in 856, causing around 45,000 deaths.
### Modern era {#modern_era}
In 1858, the old city, now known as Ancient Corinth (Αρχαία Κόρινθος, *Archaia Korinthos*), located 3 km southwest of the modern city, was totally destroyed by a magnitude 6.5 earthquake. New Corinth (*Nea Korinthos*) was then built to the north-east of it, on the coast of the Gulf of Corinth. In 1928, a magnitude 6.3 earthquake devastated the new city, which was then rebuilt on the same site. In 1933, there was a great fire, and the new city was rebuilt again.
During the German occupation in World War II, the Germans operated a Dulag transit camp for British, Australian, New Zealander and Serbian prisoners of war and a forced labour camp in the town.
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# Corinth
## Geography
Located about 78 km west of Athens, Corinth is surrounded by the coastal townlets of (clockwise) Lechaio, Isthmia, Kechries, and the inland townlets of Examilia and the archaeological site and village of ancient Corinth. Natural features around the city include the narrow coastal plain of Vocha, the Corinthian Gulf, the Isthmus of Corinth cut by its canal, the Saronic Gulf, the Oneia Mountains, and the monolithic rock of Acrocorinth, where the medieval acropolis was built.
### Climate
According to the nearby weather station of Velo, operated by the Hellenic National Meteorological Service, Corinth has a hot-summer Mediterranean climate (Köppen climate classification: *Csa*), with hot, dry summers and cool, rainy winters. The hottest month is July with an average temperature of 28.7 C while the coldest month is January with an average temperature of 9.1 C. Corinth receives about 463 mm of rainfall per year and has an average annual temperature of 18.1 C.`{{Weather box
| location = Velo, Corinth (1988–2010)
| metric first = y
| single line = y
| collapsed =
| Jan high C = 13.4
| Feb high C = 13.9
| Mar high C = 16.5
| Apr high C = 20.3
| May high C = 25.7
| Jun high C = 30.7
| Jul high C = 33.2
| Aug high C = 32.9
| Sep high C = 28.4
| Oct high C = 23.6
| Nov high C = 18.5
| Dec high C = 14.4
| Jan mean C = 9.1
| Feb mean C = 9.4
| Mar mean C = 11.9
| Apr mean C = 15.7
| May mean C = 21.1
| Jun mean C = 26.1
| Jul mean C = 28.7
| Aug mean C = 28.1
| Sep mean C = 23.4
| Oct mean C = 18.8
| Nov mean C = 13.8
| Dec mean C = 10.5
| Jan low C = 5.3
| Feb low C = 5.0
| Mar low C = 6.5
| Apr low C = 9.0
| May low C = 12.9
| Jun low C = 16.8
| Jul low C = 19.5
| Aug low C = 19.8
| Sep low C = 16.9
| Oct low C = 13.8
| Nov low C = 9.9
| Dec low C = 6.9
| precipitation colour = green
| Jan precipitation mm = 72.0
| Feb precipitation mm = 50.9
| Mar precipitation mm = 53.7
| Apr precipitation mm = 28.7
| May precipitation mm = 22.3
| Jun precipitation mm = 6.4
| Jul precipitation mm = 5.0
| Aug precipitation mm = 11.9
| Sep precipitation mm = 19.4
| Oct precipitation mm = 40.8
| Nov precipitation mm = 73.5
| Dec precipitation mm = 78.6
| source 1 =
| source = [[HNMS]]<ref>{{cite web | url=http://www.emy.gr/emy/el/climatology/climatology_city?perifereia=Peloponnese&poli=Velos_Korinthia | title=Κλιματικά Δεδομένα ανά Πόλη- ΜΕΤΕΩΓΡΑΜΜΑΤΑ, ΕΜΥ, Εθνική Μετεωρολογική Υπηρεσία }}</ref>
}}`{=mediawiki}
## Demographics
The Municipality of Corinth (Δήμος Κορινθίων) had a population of 55,941 according to the 2021 census, the second most populous municipality in the Peloponnese Region after Kalamata. The municipal unit of Corinth had 38,485 inhabitants, of which Corinth itself had 30,816 inhabitants, placing it in second place behind Kalamata among the cities of the Peloponnese Region.
The municipal unit of Corinth (Δημοτική ενότητα Κορινθίων) includes apart from Corinth proper the town of Archaia Korinthos, the town of Examilia, and the smaller settlements of Xylokeriza and Solomos. The municipal unit has an area of 102.187 km^2^.
## Economy
### Industry
Corinth is a major industrial hub at a national level. The Corinth Refinery is one of the largest oil refining industrial complexes in Europe. Ceramic tiles, copper cables, gums, gypsum, leather, marble, meat products, medical equipment, mineral water and beverages, petroleum products, and salt are produced nearby. `{{As of|2005}}`{=mediawiki}, a period of Economic changes commenced as a large pipework complex, a textile factory and a meat packing facility diminished their operations.
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# Corinth
## Transport
### Roads
Corinth is a major road hub. The A7 toll motorway for Tripoli and Kalamata, (and Sparta via the A71 toll), branches off the A8/E94 toll motorway from Athens at Corinth. Corinth is the main entry point to the Peloponnesian peninsula, the southernmost area of continental Greece.
### Bus
KTEL Korinthias provides intercity bus service in the peninsula and to Athens via the Isthmos station southeast of the city center. Local bus service is also available.
### Railways
The metre gauge railway from Athens and Pireaeus reached Corinth in 1884. This station closed to regular public transport in 2007. In 2005, two years prior, the city was connected to the Athens Suburban Railway, following the completion of the new Corinth railway station. The journey time from Athens to Corinth is about 55 minutes. The train station is 5 minutes by car from the city centre and parking is available for free.
### Port
The port of Corinth, located north of the city centre and close to the northwest entrance of the Corinth Canal, at 37 56.0' N / 22 56.0' E, serves the local needs of industry and agriculture. It is mainly a cargo exporting facility.
It is an artificial harbour (depth approximately 9 m, protected by a concrete mole (length approximately 930 metres, width 100 metres, mole surface 93,000 m2). A new pier finished in the late 1980s doubled the capacity of the port. The reinforced mole protects anchored vessels from strong northern winds.
Within the port operates a customs office facility and a Hellenic Coast Guard post. Sea traffic is limited to trade in the export of local produce, mainly citrus fruits, grapes, marble, aggregates and some domestic imports. The port operates as a contingency facility for general cargo ships, bulk carriers and ROROs, in case of strikes at Piraeus port.
#### Ferries
There was formerly a ferry link to Catania, Sicily and Genoa in Italy.
### Canal
The Corinth Canal, carrying ship traffic between the western Mediterranean Sea and the Aegean Sea, is about 4 km east of the city, cutting through the Isthmus of Corinth that connects the Peloponnesian peninsula to the Greek mainland, thus effectively making the former an island. The builders dug the canal through the Isthmus at sea level; no locks are employed. It is 6.4 km in length and only 21.3 m wide at its base, making it impassable for most modern ships. It now has little economic importance.
The canal was mooted in ancient times and an abortive effort was made to dig it in around 600 BC by Periander which led him to pave the Diolkos highway instead. Julius Caesar and Caligula both considered digging the canal but died before starting the construction. The emperor Nero then directed the project, which consisted initially of a workforce of 6,000 Jewish prisoners of war, but it was interrupted because of his death. The project resumed only in 1882, after Greece gained independence from the Ottoman Empire, but was hampered by geological and financial problems that bankrupted the original builders. It was finally completed in 1893, but due to the canal\'s narrowness, navigational problems and periodic closures to repair landslips from its steep walls, it failed to attract the level of traffic anticipated by its operators. It is now used mainly for tourist traffic.
## Sport
The city\'s association football team is Korinthos F.C. (*Π.Α.E. Κόρινθος*), established in 1999 after the merger of Pankorinthian Football Club (*Παγκορινθιακός*) and Corinth Football Club (*Κόρινθος*). During the 2006--2007 season, the team played in the Greek Fourth Division\'s Regional Group 7. The team went undefeated that season and it earned the top spot. This granted the team a promotion to the Gamma Ethnikí (Third Division) for the 2007--2008 season. For the 2008--2009 season, Korinthos F.C. competed in the Gamma Ethniki (Third Division) southern grouping.
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# Corinth
## Twin towns/sister cities {#twin_townssister_cities}
Corinth is twinned with:
- Syracuse, Sicily
- Jagodina, Serbia
## Notable people {#notable_people}
- Anastasios Bakasetas (1993--), Greek footballer
- Evangelos Ikonomou (1987--), Greek footballer
- George Kollias (1977--), drummer for US technical death metal band Nile.
- Georgios Leonardopoulos, army officer
- Macarius (1731--1805), Metropolitan bishop of Corinth
- Ioannis Papadiamantopoulos (1766--1826), revolutionary leader during the Greek War of Independence.
- Irene Papas (1929--2022), Greek actress
- Costas Soukoulis (1951--2024), Professor of Physics at Iowa State University
- Konstantinos Triantafyllopoulos (1993--) Greek footballer
- Panagis Tsaldaris (1868--1936), Greek politician and prime minister of Greece
- Panagiotis Tzanavaras (1964--), Greek footballer and football manager
- Nikolaos Zafeiriou (1871--1947), Greek artillery officer
## Other locations named after Corinth {#other_locations_named_after_corinth}
Due to its ancient history and the presence of St. Paul the Apostle in Corinth some locations all over the world have been named Corinth.
## Gallery
<File:Pegasus> Square in New Corinth.jpg\|Pegasus Square in New Corinth <File:Squarecorinth.jpg%7CView> of the Central Square of the city <File:Istmo> de Corinto ESC large ISS011 ISS011-E-13188
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# Charge of the Goddess
The **Charge of the Goddess** (or **Charge of the Star Goddess**) is an inspirational text often used in the neopagan religion of Wicca. The Charge of the Goddess is recited during most rituals in which the Wiccan priest/priestess is expected to represent, and/or embody, the Goddess within the sacred circle, and is often spoken by the High Priest/Priestess after the ritual of Drawing Down the Moon.
The Charge is the promise of the Goddess (who is embodied by the high priestess) to all witches that she will teach and guide them. It has been called \"perhaps the most important single theological document in the neo-Pagan movement\". It is used not only in Wicca, but as part of the foundational documents of the Reclaiming tradition of witchcraft co-founded by Starhawk.
Several versions of the Charge exist, though they all have the same basic premise, that of a set of instructions given by the Great Goddess to her worshippers. The earliest version is that compiled by Gerald Gardner. This version, titled \"Leviter Veslis\" or \"Lift Up the Veil\", includes material paraphrased from works by Aleister Crowley, primarily from Liber AL (The Book of the Law, particularly from Ch 1, spoken by Nuit, the Star Goddess), and from Liber LXV (The Book of the Heart Girt with a Serpent) and from Crowley\'s essay \"The Law of Liberty\", thus linking modern Wicca to the cosmology and revelations of Thelema. It has been shown that Gerald Gardner\'s book collection included a copy of Crowley\'s *The Blue Equinox* (1919) which includes all of the Crowley quotations transferred by Gardner to the Charge of the Goddess.
There are also two versions written by Doreen Valiente in the mid-1950s, after her 1953 Wiccan initiation. The first was a poetic paraphrase which eliminated almost all the material derived from Leland and Crowley. The second was a prose version which is contained within the traditional Gardnerian Book of Shadows and more closely resembles Gardner\'s \"Leviter Veslis\" version of 1949.
Several different versions of a Wiccan Charge of the God have since been created to mirror and accompany the Charge of the Goddess.
## Themes
The opening paragraph names a collection of goddesses, some derived from Greek or Roman mythology, others from Celtic or Arthurian legends, affirming a belief that these various figures represent a single Great Mother: `{{blockquote|Listen to the words of the Great Mother, who was of old also called [[Artemis]]; [[Astarte]]; [[Diana (mythology)|Diana]]; [[Melusine]]; [[Aphrodite]]; [[Cerridwen]]; [[Danu (Irish goddess)|Dana]]; [[Arianrhod]]; [[Isis]]; [[Brigid|Bride]]; and by many other names.|source=Charge of the Goddess<ref name="ValienteWebsite">{{cite web |title=Doreen Valiente Poetry |url=http://www.doreenvaliente.com/Doreen-Valiente-Doreen_Valiente_Poetry-11.php#sthash.OvFLVGe4.dpbs |website=The Official Doreen Valiente Website |access-date=18 March 2021 |language=en}}</ref>|author=Doreen Valiente}}`{=mediawiki}
This theme echoes the ancient Roman belief that the Goddess Isis was known by ten thousand names and also that the Goddess still worshipped today by Wiccans and other neopagans is known under many guises but is in fact one universal divinity.
The second paragraph is largely derived and paraphrased from the words that Aradia, the messianic daughter of Diana, speaks to her followers in Charles Godfrey Leland\'s 1899 book *Aradia, or the Gospel of the Witches* (London: David Nutt; various reprints). The third paragraph is largely written by Doreen Valiente, with a significant content of phrases loosely from *The Book of the Law* and *The Book of the Heart Girt with the Serpent* by Aleister Crowley.
The charge affirms that *all* acts of love and pleasure are sacred to the Goddess, e.g.:
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# Charge of the Goddess
## History
### Ancient precedents {#ancient_precedents}
In book eleven, chapter 47 of Apuleius\'s *The Golden Ass*, Isis delivers what Ceisiwr Serith calls \"essentially a charge of a goddess\". This is rather different from the modern version known in Wicca, though they have the same premise, that of the rules given by a great Mother Goddess to her faithful.
The Charge of the Goddess is also known under the title *Leviter Veslis*. This has been identified by the historian Ronald Hutton, cited in an article by Roger Dearnsley \"The Influence of Aleister Crowley on *Ye Bok of Ye Art Magical*, as a piece of medieval ecclesiastical Latin used to mean \"lifting the veil.\" However, Hutton\'s interpretation does not reflect the Latin grammar as it currently stands. It may represent Gardner\'s attempt to write *Levetur Velis*, which has the literal meaning of \"Let the veil be lifted.\" This expression would, by coincidence or design, grammatically echo the famous *fiat lux* (*Gen. 1:3*) of the Latin Vulgate.
### Origins
The earliest known Wiccan version is found in a document dating from the late 1940s, Gerald Gardner\'s ritual notebook titled *Ye Bok of Ye Art Magical*. The oldest identifiable source contained in this version is the final line, which is traceable to the 17th-century *Centrum Naturae Concentratum* of Alipili (or Ali Puli). This version also draws extensively from Charles Godfrey Leland\'s *Aradia, or the Gospel of the Witches* (1899) and other modern sources, particularly from the works of Aleister Crowley.
It is believed to have been compiled by Gerald Gardner or possibly another member of the New Forest coven. Gardner intended his version to be a theological statement justifying the Gardnerian sequence of initiations. Like the Charge found in Freemasonry, where the charge is a set of instructions read to a candidate standing in a temple, the Charge of the Goddess was intended to be read immediately before an initiation.
Valiente felt that the influence of Crowley on the Charge was too obvious, and she did not want \"the Craft\" (a common term for Wicca) associated with Crowley. Gardner invited her to rewrite the Charge. She proceeded to do so, her first version being into verse.
The initial verse version by Doreen Valiente consisted of eight verses, the second of which was:
Valiente was unhappy with this version, saying that \"people seemed to have some difficulty with this, because of the various goddess-names which they found hard to pronounce\", and so she rewrote it as a prose version, much of which differs from her initial version, and is more akin to Gardner\'s version. This prose version has since been modified and reproduced widely by other authors
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# Chomsky (surname)
**Chomsky** (*Chomski*, *Хомскі*, *Хомский*, *Хомський*, *חומסקי*, \"from (Vyoska) Chomsk/ Khomsk (nearby Brest, now Belarus)\") is a surname of Slavic origin. Notable people with the surname include:
- Alejandro Chomski (born 1968), Argentine film director and screenwriter
- Aviva Chomsky (born 1957), American historian
- Carol (Schatz) Chomsky (1930--2008), American linguist and wife of Noam Chomsky
- Judith Chomsky (born 1942), American human rights lawyer and co-founder of the Juvenile Law Center
- Marvin J
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# Computer multitasking
In computing, **multitasking** is the concurrent execution of multiple tasks (also known as processes) over a certain period of time. New tasks can interrupt already started ones before they finish, instead of waiting for them to end. As a result, a computer executes segments of multiple tasks in an interleaved manner, while the tasks share common processing resources such as central processing units (CPUs) and main memory. Multitasking automatically interrupts the running program, saving its state (partial results, memory contents and computer register contents) and loading the saved state of another program and transferring control to it. This \"context switch\" may be initiated at fixed time intervals (pre-emptive multitasking), or the running program may be coded to signal to the supervisory software when it can be interrupted (cooperative multitasking).
Multitasking does not require parallel execution of multiple tasks at exactly the same time; instead, it allows more than one task to advance over a given period of time. Even on multiprocessor computers, multitasking allows many more tasks to be run than there are CPUs.
Multitasking is a common feature of computer operating systems since at least the 1960s. It allows more efficient use of the computer hardware; when a program is waiting for some external event such as a user input or an input/output transfer with a peripheral to complete, the central processor can still be used with another program. In a time-sharing system, multiple human operators use the same processor as if it was dedicated to their use, while behind the scenes the computer is serving many users by multitasking their individual programs. In multiprogramming systems, a task runs until it must wait for an external event or until the operating system\'s scheduler forcibly swaps the running task out of the CPU. Real-time systems such as those designed to control industrial robots, require timely processing; a single processor might be shared between calculations of machine movement, communications, and user interface.
Often multitasking operating systems include measures to change the priority of individual tasks, so that important jobs receive more processor time than those considered less significant. Depending on the operating system, a task might be as large as an entire application program, or might be made up of smaller threads that carry out portions of the overall program.
A processor intended for use with multitasking operating systems may include special hardware to securely support multiple tasks, such as memory protection, and protection rings that ensure the supervisory software cannot be damaged or subverted by user-mode program errors.
The term \"multitasking\" has become an international term, as the same word is used in many other languages such as German, Italian, Dutch, Romanian, Czech, Danish and Norwegian.
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# Computer multitasking
## Multiprogramming
In the early days of computing, CPU time was expensive, and peripherals were very slow. When the computer ran a program that needed access to a peripheral, the central processing unit (CPU) would have to stop executing program instructions while the peripheral processed the data. This was usually very inefficient. Multiprogramming is a computing technique that enables multiple programs to be concurrently loaded and executed into a computer\'s memory, allowing the CPU to switch between them swiftly. This optimizes CPU utilization by keeping it engaged with the execution of tasks, particularly useful when one program is waiting for I/O operations to complete.
The Bull Gamma 60, initially designed in 1957 and first released in 1960, was the first computer designed with multiprogramming in mind. Its architecture featured a central memory and a Program Distributor feeding up to twenty-five autonomous processing units with code and data, and allowing concurrent operation of multiple clusters.
Another such computer was the LEO III, first released in 1961. During batch processing, several different programs were loaded in the computer memory, and the first one began to run. When the first program reached an instruction waiting for a peripheral, the context of this program was stored away, and the second program in memory was given a chance to run. The process continued until all programs finished running.
Multiprogramming gives no guarantee that a program will run in a timely manner. Indeed, the first program may very well run for hours without needing access to a peripheral. As there were no users waiting at an interactive terminal, this was no problem: users handed in a deck of punched cards to an operator, and came back a few hours later for printed results. Multiprogramming greatly reduced wait times when multiple batches were being processed.
## `{{Anchor|COOP|Cooperative multitasking/time-sharing}}`{=mediawiki}Cooperative multitasking {#cooperative_multitasking}
Early multitasking systems used applications that voluntarily ceded time to one another. This approach, which was eventually supported by many computer operating systems, is known today as cooperative multitasking. Although it is now rarely used in larger systems except for specific applications such as CICS or the JES2 subsystem, cooperative multitasking was once the only scheduling scheme employed by Microsoft Windows and classic Mac OS to enable multiple applications to run simultaneously. Cooperative multitasking is still used today on RISC OS systems.
As a cooperatively multitasked system relies on each process regularly giving up time to other processes on the system, one poorly designed program can consume all of the CPU time for itself, either by performing extensive calculations or by busy waiting; both would cause the whole system to hang. In a server environment, this is a hazard that makes the entire environment unacceptably fragile.
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# Computer multitasking
## Preemptive multitasking {#preemptive_multitasking}
Preemptive multitasking allows the computer system to more reliably guarantee to each process a regular \"slice\" of operating time. It also allows the system to deal rapidly with important external events like incoming data, which might require the immediate attention of one or another process. Operating systems were developed to take advantage of these hardware capabilities and run multiple processes preemptively. Preemptive multitasking was implemented in the PDP-6 Monitor and Multics in 1964, in OS/360 MFT in 1967, and in Unix in 1969, and was available in some operating systems for computers as small as DEC\'s PDP-8; it is a core feature of all Unix-like operating systems, such as Linux, Solaris and BSD with its derivatives, as well as modern versions of Windows.
Possibly the earliest preemptive multitasking OS available to home users was Microware\'s OS-9, available for computers based on the Motorola 6809 such as the TRS-80 Color Computer 2, with the operating system supplied by Tandy as an upgrade for disk-equipped systems. Sinclair QDOS on the Sinclair QL followed in 1984, but it was not a big success. Commodore\'s Amiga was released the following year, offering a combination of multitasking and multimedia capabilities. Microsoft made preemptive multitasking a core feature of their flagship operating system in the early 1990s when developing Windows NT 3.1 and then Windows 95. In 1988 Apple offered A/UX as a UNIX System V-based alternative to the Classic Mac OS. In 2001 Apple switched to the NeXTSTEP-influenced Mac OS X.
A similar model is used in Windows 9x and the Windows NT family, where native 32-bit applications are multitasked preemptively. 64-bit editions of Windows, both for the x86-64 and Itanium architectures, no longer support legacy 16-bit applications, and thus provide preemptive multitasking for all supported applications.
## Real time {#real_time}
Another reason for multitasking was in the design of real-time computing systems, where there are a number of possibly unrelated external activities needed to be controlled by a single processor system. In such systems a hierarchical interrupt system is coupled with process prioritization to ensure that key activities were given a greater share of available process time.
## Multithreading
Threads were born from the idea that the most efficient way for cooperating processes to exchange data would be to share their entire memory space. Thus, threads are effectively processes that run in the same memory context and share other resources with their parent processes, such as open files. Threads are described as *lightweight processes* because switching between threads does not involve changing the memory context.
While threads are scheduled preemptively, some operating systems provide a variant to threads, named *fibers*, that are scheduled cooperatively. On operating systems that do not provide fibers, an application may implement its own fibers using repeated calls to worker functions. Fibers are even more lightweight than threads, and somewhat easier to program with, although they tend to lose some or all of the benefits of threads on machines with multiple processors.
Some systems directly support multithreading in hardware.
## Memory protection {#memory_protection}
Essential to any multitasking system is to safely and effectively share access to system resources. Access to memory must be strictly managed to ensure that no process can inadvertently or deliberately read or write to memory locations outside the process\'s address space. This is done for the purpose of general system stability and data integrity, as well as data security.
In general, memory access management is a responsibility of the operating system kernel, in combination with hardware mechanisms that provide supporting functionalities, such as a memory management unit (MMU). If a process attempts to access a memory location outside its memory space, the MMU denies the request and signals the kernel to take appropriate actions; this usually results in forcibly terminating the offending process. Depending on the software and kernel design and the specific error in question, the user may receive an access violation error message such as \"segmentation fault\".
In a well designed and correctly implemented multitasking system, a given process can never directly access memory that belongs to another process. An exception to this rule is in the case of shared memory; for example, in the System V inter-process communication mechanism the kernel allocates memory to be mutually shared by multiple processes. Such features are often used by database management software such as PostgreSQL.
Inadequate memory protection mechanisms, either due to flaws in their design or poor implementations, allow for security vulnerabilities that may be potentially exploited by malicious software.
## Memory swapping {#memory_swapping}
Use of a swap file or swap partition is a way for the operating system to provide more memory than is physically available by keeping portions of the primary memory in secondary storage. While multitasking and memory swapping are two completely unrelated techniques, they are very often used together, as swapping memory allows more tasks to be loaded at the same time. Typically, a multitasking system allows another process to run when the running process hits a point where it has to wait for some portion of memory to be reloaded from secondary storage.
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# Computer multitasking
## Programming
Over the years, multitasking systems have been refined. Modern operating systems generally include detailed mechanisms for prioritizing processes, while symmetric multiprocessing has introduced new complexities and capabilities
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# Concordat of Worms
upright=1.5\|alt=Image of the original document\|thumb\|The Concordat of Worms, written in Papal minuscule on Vellum The **Concordat of Worms** (*Concordatum Wormatiense*; *Wormser Konkordat*), also referred to as the ***Pactum Callixtinum**\'\' or***Pactum Calixtinum**\'\', was an agreement between the Catholic Church and the Holy Roman Empire which regulated the procedure for the appointment of bishops and abbots in the Empire. Signed on 23 September 1122 in the German city of Worms by Pope Callixtus II and Emperor Henry V, the agreement set an end to the Investiture Controversy, a conflict between state and church over the right to appoint religious office holders that had begun in the middle of the 11th century.
By signing the concordat, Henry renounced his right to invest bishops and abbots with ring and crosier, and opened ecclesiastical appointments in his realm to canonical elections. Callixtus, in turn, agreed to the presence of the emperor or his officials at the elections and granted the emperor the right to intervene in the case of disputed outcomes. The emperor was also allowed to perform a separate ceremony in which he would invest bishops and abbots with a sceptre, representing the lands that constituted the temporalities associated with their episcopal see.
## Background
During the middle of the 11th century, a reformist movement within the Christian Church sought to reassert the rights of the Holy See at the expense of the European monarchs. Having been elected in 1073, the reformist Pope Gregory VII proclaimed several edicts aimed at strengthening the authority of the papacy, some of which were formulated in the *Dictatus papae* of 1075. Gregory\'s edicts postulated that secular rulers were answerable to the pope and forbade them to make appointments to clerical offices (a process known as investiture).
The pope\'s doctrines were vehemently rejected by Henry IV, the Holy Roman Emperor, who habitually invested the bishops and abbots of his realm. The ensuing conflict between the Empire and the papacy is known as the Investiture Controversy. The dispute continued after the death of Gregory VII in 1084 and the abdication of Henry IV in 1105.
Even though Henry\'s son and successor, the Emperor Henry V, looked towards reconciliation with the reformist movement, no lasting compromise was achieved in the first 16 years of his reign. In 1111, Henry V brokered an agreement with Pope Paschal II at Sutri, whereby he would abstain from investing clergy in his realm in exchange for the restoration of church property that had originally belonged to the Empire. The Sutri agreement, Henry hoped, would convince Paschal to assent to Henry\'s official coronation as emperor.
The agreement failed to be implemented, leading Henry to imprison the pope. After two months of captivity, Paschal vowed to grant the coronation and to accept the emperor\'s role in investiture ceremonies. He also agreed never to excommunicate Henry. Given that these concessions had been won by force, ecclesiastical opposition to the Empire continued. The following year, Paschal reneged on his promises.
## Mouzon summit {#mouzon_summit}
In January 1118, Pope Paschal died. He was succeeded by Gelasius II, who died in January 1119. His successor, the Burgundian Callixtus II, resumed negotiations with the Emperor with the aim of settling the dispute between the church and the Empire. In the autumn of 1119, two papal emissaries, William of Champeaux and Pons of Cluny, met Henry at Strasbourg, where the emperor agreed in principle to abandon the secular investiture ceremony that involved giving new bishops and abbots a ring and a crosier.
The two parties scheduled a final summit between Henry and Callixtus at Mouzon, but the meeting ended abruptly after the emperor refused to accept a short-notice change in Callixtus\'s demands. The church leaders, who were deliberating their position at a council in Reims, reacted by excommunicating Henry. However, they did not endorse the pope\'s insistence upon the complete abandonment of secular investiture. The negotiations ended in failure.
Historians disagree as to whether Calixtus actually wanted peace or fundamentally mistrusted Henry. Due to his uncompromising position in 1111, Calixtus has been termed an \"ultra\", and his election to the papacy may indicate that the College of Cardinals saw no reason to show weakness to the emperor. This optimism about victory was founded on the very visible, and very vocal opposition to Henry from within his own nobility, and the cardinals may have seen the emperor\'s internal weaknesses as an opportunity for outright victory.
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# Concordat of Worms
## Further negotiations {#further_negotiations}
After the failure of the Mouzon negotiations, and the disappearance into the horizon of the chances of Henry\'s unconditional surrender, the majority of the clergy became willing to compromise in order to settle the dispute. The polemic writings and pronouncements that had figured so highly during the Investiture Dispute had died down by this point. Historian Gerd Tellenbach argues that, despite appearances, these years were \"no longer marked by an atmosphere of bitter conflict\".
This was in part the result of the papacy\'s realization that it could not win two different disputes on two separate fronts, as it had been trying to do. Calixtus had been personally involved in negotiations with the Emperor over the last decade, and his intimate knowledge of the delicate situation made him the perfect candidate for the attempt. The difference between 1119 and 1122, argues Stroll, was not Henry, who had been willing to make concessions in 1119, but Calixtus, who had then been intransigent, but who now was intent upon reaching an agreement\". `{{multiple image
| align = right
| total_width = 400
| image1 = Emperor Henry V cropped.png
| alt1 = Hebry V, from an 1130 [[fresco]] from St George abbey church, [[Regensburg-Prüfening]]
| caption1 = {{center|[[Henry V, Holy Roman Emperor]]}}
| image2 = Calixtus II.jpg
| alt2 = Pope Calixtus II. From: from the "Liber ad honorem Augusti" of [[Petrus of Ebulo]], 1196
| caption2 = {{center|[[Calixtus II]]}}
| footer =
}}`{=mediawiki}
The same sentiment prevailed in much of the German nobility. In 1121, pressured by a faction of nobles from the Lower Rhine and Duchy of Saxony under the leadership of the archbishop Adalbert of Mainz, Henry agreed to submit to make peace with the pope. In response in February 1122, Calixtus wrote to Henry in a conciliatory tone via the Bishop of Acqui. His letter has been described as \"a carefully crafted overture\".
In his letter, Calixtus drew attention to their blood relationship, suggesting that while their shared ancestry compelled them to love each other as brothers, it was fundamental that the German kings draw their authority from God, but via his servants, not directly. However, Calixtus also emphasised for the first time that he blamed not Henry personally for the dispute but his bad advisors who had dictated unsound policy to him. In a major shift in policy since the Council of Reims of 1119, the pope stated that the church gifts what it possesses to all its children, without making claims upon them. This was intended to reassure Henry that in the event of peace between them, his position and Empire were secure.
Shifting from the practical to the spiritual, Calixtus next asked Henry to bear in mind that he was a king, but like all men limited on his earthly capability; he had armies, and kings below him, but the church had Christ and the Apostles. Continuing his theme, he referred, indirectly, to Henry\'s excommunication by himself (twice), he begged Henry to allow the conditions for peace to be created, as a result of which the church\'s, and God\'s glory would be increased, as concomitantly would the Emperor\'s. Conversely, he made sure to include a threat: if Henry did not change his ways, Calixtus threatened to place \"the protection of the church in the hands of wise men\".
Historian Mary Stroll argues that, in taking this approach, Calixtus was taking advantage of the fact that, while he himself \"was hardly in a position to sabre rattle\" due to his military defeat in the south and his difficulty with his own Cardinals, Henry was also under pressure in Germany in both the military and spiritual spheres.
The Emperor replied through the Bishop of Speyer and the Abbot of Fulda, who travelled to Rome and collected the pope\'s emissaries under the Cardinal Bishop of Ostia. Speyer was a representative of Henry\'s political opponents in Germany, whereas Fulda was a negotiator rather than politically partisan. Complicating matters was a disputed election to the bishopric of Wurzburg in February 1122 of the kind that was at the heart of the Investiture Dispute. Although this almost led to an outbreak of civil war, a truce was arranged in August, allowing the parties to return to the papal negotiations.
In the summer of 1122, a synod was convened in Mainz, at which imperial emissaries concluded the terms of their agreement with representatives of the church. In a sign that the Pope intended the impending negotiations to be successful, a Lateran council was announced for the following year.
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# Concordat of Worms
## Worms
The Emperor received the papal legates in Worms with due ceremony, where he awaited the outcome of the negotiations which appear to have actually taken place in nearby Mainz, which was hostile territory to Henry. As such, he had to communicate via messenger to keep up with events. Abbot Ekkehard of Aura chronicles that discussions took over a week to conclude. On 8 September, he met the papal legates and their final agreements were codified for publication.
Although a possible compromise solution had already been received from England, this does not seem to have ever been considered in depth, probably on account of it containing an oath of Homage between Emperor and Pope, which had been a historical sticking point in earlier negotiations. The papal delegation was led by Cardinal bishop Lamberto Scannabecchi of Ostia, the future Pope Honorius II.
Both sides studied previous negotiations between them, including those from 1111, which were considered to have created precedent. On 23 September 1122, papal and imperial delegates signed a series of documents outside the walls of Worms. There was insufficient room in the city for the number of attendees and watchers. Adalbert, Archbishop of Mainz wrote to Calixtus of how complex the negotiations had been, given that, as he said, Henry regarded the powers he was being asked to renounce as being hereditary in the Imperial throne. It is probable that what was eventually promulgated was the result of almost every word being carefully considered. The main difference between what was to be agreed at Worms and previous negotiations were the concessions from the pope.
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# Concordat of Worms
## Concordat
The agreements come to at Worms were in the nature of both concessions and assurances to the other party. Henry, on oath before God, the apostles and the church renounced his right to invest bishops and abbots with ring and crosier, and opened ecclesiastical appointments in his realm to canonical elections, *regno vel imperio*. He also recognised the traditional extent and boundaries of the papal patrimony as a legal entity rather than one malleable to the emperor. Henry promised to return to the church those lands rightfully belonging to the church seized by himself or his father to the church; furthermore, he would assist the pope in regaining those that were taken by others, and \"he will do the same thing for all other churches and princes, both ecclesiastical and lay\". If the pope requested Imperial assistance, he would receive it, and if the church came to the empire for justice, it would be treated fairly. He also swore to abstain from \"all investiture by ring and staff\", marking the end of an ancient imperial tradition.
Callixtus made similar reciprocal promises regarding the empire in Italy. He agreed to the presence of the emperor or his officials at the elections and granted the emperor the right to ajudge in the case of disputed outcomes on episcopal advice---as long as they had been held peacefully and without simony---which had officially been the case ever since precedent had been set by the London Accord of 1107. This right to judge was constrained by an assurance that he would support the majority vote among electors, and further that he would take the advice of his other bishops before doing so. The emperor was also allowed to perform a separate ceremony in which he would invest bishops and abbots with their *regalia*, a sceptre representing the imperial lands associated with their episcopal see. This clause also contained a \"cryptic\" condition that once the elect had been so endowed, the new bishop \"should do what he ought to do according to imperial rights\". In the German imperial lands this was to take place prior to the bishop-elect\'s consecration; elsewhere in the empire---Burgundy and Italy, exempting the Papal States---within six months of the ceremony. The differentiating between the German portion of the Empire and the rest was of particular importance to Calixtus as the papacy had traditionally felt threatened more from it in the peninsular than the broader Empire. Finally, the pope granted \"true peace\" on the emperor and all those who had supported him. Calixtus had effectively overturned wholesale the strategy he had pursued during the Mouzon negotiation; episcopal investitures in Germany were to take place with very little substantive change in ceremony, while temporal involvement remained, only replacing investiture with homage, although the word itself---*hominium*---was studiously avoided. Adalbert, from whom Calixtus first received news of the final concordat, emphasized that it still had to be approved in Rome; this suggests, argues Stroll, that the Archbishop---and probably the papal legation as a whole---were against making concessions to the emperor, and probably wanted Calixtus to disown the agreement. Adalbert believed the agreement would make it easier for the Emperor to legalise intimidation of episcopal electors, writing that \"through the opportunity of \[the emperor\'s\] presence, the Church of God must undergo the same slavery as before, or an even more oppressive one\".
However, argues Stroll, the concessions Calixtus made were an \"excellent bargain\" in return for eradicating the danger on the papacy\'s northern border and therefore allowing him to focus, without threat or distraction, on the Normans to the south. It had achieved its peace, argues Norman Cantor, by allowing local national custom and practice to determine future relations between crown and pope; in most cases, he notes, this \"favored the continuance of royal control over the church\".
The concordat was published as two distinct charters, each laying out the concessions the one party was making to the other. They are known respectively as the Papal (or the *Calixtinum*) and the Imperial (*Henricianum*) charters. Calixtus\'s is addressed to the emperor---in quite personal terms---while Henry\'s is made out to God. The bishop of Ostia gave the emperor the kiss of peace on behalf of the pope and said Mass. By these rites was Henry returned to the church, the negotiators were lauded for succeeding in their delicate mission and the concordat was called \"peace at the will of the pope\". Neither charter was signed; both contained probably intentional vagaries and unanswered questions---such as the position of the papacy\'s churches that lay outside both the patrimony and Germany---which were subsequently addressed on a case-by-case basis. Indeed, Robert Benson has suggested that the brevity of the charters was deliberate and that the agreement as a whole is as important for what it omits as for what it includes. The term *regalia*, for example, was not only undefined but literally meant two different things to each party. In the *Henricianum* it referred to the feudal duty owed to a monarch; in the Calixtinium, it was the episcopal temporalities. Broader question, such as the nature of the church and Empire relationship, were also not addressed, although some ambiguity was removed by an 1133 Papal privilege.
The Concordat was widely, and deliberately, publicised around Europe. Calixtus was not in Rome when the concordat was delivered. He had left the city by late August and was not to return until mid- to late October, making a progress to Anagni, taking the bishopric of Anagni and Casamari Abbey under his protection.
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# Concordat of Worms
## Concordat
### Agreements
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| Agreement of Calixtus II | Edict of Henry V |
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| I, Calixtus, bishop, servant of the servants of God, do grant to thee, beloved son, Henry---by the grace of God emperor of the Romans, Augustus---that the elections of bishops and abbots of the German kingdom, who belong to that kingdom, shall take place in thy presence, without simony or any violence; so that if any dispute shall arise between the parties concerned, thou, with the counsel or judgment of the metropolitan and the coprovincial bishops, shalt give consent and aid to the party which has the more right. The one elected shall receive the regalia from thee by the scepter and shall perform his lawful duties to thee on that account. But he who is consecrated in the other parts of thy empire \[i.e., Burgundy and Italy\] shall, within six months, and without any exaction, receive the regalia from thee by the scepter, and shall perform his lawful duties to thee on that account (saving all rights which are known to belong to the Roman Church). Concerning matters in which thou shalt make complaint to me, and ask aid---I, according to the duty of my office, will furnish aid to thee. I give unto thee true peace, and to all who are or have been of thy party in this conflict. | In the name of the holy and indivisible Trinity I, Henry, by the grace of God emperor of the Romans, Augustus, for the love of God and of the Holy Roman Church and of our lord Pope Calixtus, and for the salvation of my soul, do surrender to God, and to the holy apostles of God, Peter and Paul, and to the Holy Catholic Church, all investiture through ring and staff; and do grant that in all the churches that are in my kingdom or empire there may be canonical election and free consecration. All the possessions and regalia of St. Peter which, from the beginning of this discord unto this day, whether in the time of my father or in mine have been seized, and which I hold, I restore to that same Holy Roman Church. And I will faithfully aid in the restoration of those things which I do not hold. The possessions also of all other churches and princes, and of all other persons lay and clerical which have been lost in that war: according to the counsel of the princes, or according to justice, I will restore, as far as I hold them; and I will faithfully aid in the restoration of those things which I do not hold. And I grant true peace to our lord Pope Calixtus, and to the Holy Roman Church, and to all those who are or have been on its side. And in matters where the Holy Roman Church shall ask aid I will grant it; and in matters concerning which it shall make complaint to me I will duly grant to it justice. All these things have been done by the consent and counsel of the princes. Whose names are here adjoined: Adalbert archbishop of Mainz; F. archbishop of Cologne; H. bishop of Ratisbon; O. bishop of Bamberg; B. bishop of Spires; H. of Augsburg; G. of Utrecht; Ou. of Constance; E. abbot of Fulda; Henry, duke; Frederick, duke; S. duke; Pertolf, duke; Margrave Teipold; Margrave Engelbert; Godfrey, count Palatine; Otto, count Palatine; Berengar, count. |
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| | I, Frederick, archbishop of Cologne and arch-chancellor, have ratified this. |
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# Concordat of Worms
## Concordat
### Preservation
The concordat was ratified at the First Council of the Lateran and the original *Henricianum* charter is preserved at the Vatican Apostolic Archive; the *Calixtinum* has not survived except in subsequent copies. A copy of the former is also held in the *Codex Udalrici*, but this is an abridged version for political circulation, as it reduces the number of imperial concessions made. Indicating the extent that he saw the agreement as a papal victory, Calixtus had a copy of the *Henricianum* painted on a Lateran Palace chamber wall; while nominally portraying the concordat as a victory for the papacy, it also ignored the numerous concessions made to the emperor. This was part of what Hartmut Hoffmann has called \"a conspiracy of silence\" regarding papal concessions. Indeed, while the Pope is pictured enthroned, and Henry only standing, the suggestion is still that they were jointly wielding their respective authority to come to this agreement. An English copy of the *Calixtinum* made by William of Malmsbury is reasonably accurate but omits the clause mentioning the use of a sceptre in the granting of the *regalia*. He then, having condemned Henry\'s \"Teuton fury\", proceeds to praise him, comparing him favourably to Charlemagne for his devotion to God and the peace of Christendom.
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# Concordat of Worms
## Aftermath
The first invocation of the concordat was not in the empire, as it turned out, but by Henry I of England the following year. Following a long-running dispute between Canterbury--York which ended up in the Papal court, Joseph Huffman argues that it would have been controversial for the Pope \"to justify one set of concessions in Germany and another in England\". The concordat ended once and for all the \"Imperial church system of the Ottonians and Salians\". The First Lateran Council was convoked to confirm the Concordat of Worms. The council was most representative with nearly 300 bishops and 600 abbots from every part of Catholic Europe being present. It convened on March 18, 1123. One of its primary concerns was to emphasise the independence of diocesan clergy, and to do so it forbade monks to leave their monasteries to provide pastoral care, which would in future be the sole preserve of the diocese. In ratifying the Concordat, the Council confirmed that in future bishops would be elected by their clergy, although, also per the Concordat, the Emperor could refuse the homage of German bishops.
Decrees were passed directed against simony, concubinage among the clergy, church robbers, and forgers of Church documents; the council also reaffirmed indulgences for Crusaders. These, argues C. Colt Anderson \"established important precedents in canon law restricting the influence of the laity and the monks\". While this led to a busy period of reform, it was important for those advocating reform not to allow themselves to be confused with the myriad heretical sects and schismatics who were making similar criticisms.
The Concordat was the last major achievement for Emperor Henry, as he died in 1125; an attempted invasion of France came to nothing in 1124 in the face of \"determined opposition\". Fuhrmann comments that, as Henry had shown in his life \"even less interest in new currents of thought and feeling than his father\", he probably did not understand the significance of the events he had lived through. The peace only lasted until his death; when Imperial Electors met to choose his successor, reformists took the opportunity to attack the imperial gains of Worms on the grounds that they had been granted to him personally rather than Emperors generally. However, later emperors, such as Frederick I and Henry VI, continued to wield as much, if intangible, power as their predecessors in episcopal elections, and to a greater degree to that allowed them by Calixtus\' charter. Successive emperors found the Concordat sufficiently favourable that it remained, almost unaltered until the empire was dissolved by Francis II in 1806 on account of Napoleon. Popes, likewise, were able to use the powers codified to them in the Concordatto their advantage in future internal disputes with their Cardinals.
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# Concordat of Worms
## Reception
The most detailed contemporary description of the Concordat comes to historians through a brief chronicle known as the 1125 continuation chronicle. This pro-papal document lays the blame for the schism squarely upon Henry---by his recognition of Gregory VIII---and the praise for ending it on Calixtus, through his making only temporary compromises. I. S. Robinson, writing in The New Cambridge Medieval History, suggests that this was a deliberate ploy to leave further negotiations open with a more politically malleable Emperor in future. To others it was not so clear cut; Honorius of Autun, for example, writing later in the century discussed lay investiture as an aspect of papal-Imperial relations and, even a century later the *Sachsenspiegel* still stated that Emperors nominated bishops in Germany. Robinson suggests that, by the end of the 12th century, \"it was the imperial, rather than the papal version of the Concordat of Worms that was generally accepted by German churchmen\".
The contemporary English historian William of Malmesbury praised the Concordat for curtailing what he perceived as the emperor\'s overreach, or as he put it, \"severing the sprouting necks of Teuton fury with the axe of Apostolic power\". However, he regarded the final settlement not as a defeat of the Empire at the hands of the church, but rather as a reconciliatory effort by the two powers. Although polemicism had died down in the years preceding the Concordat, it did not finish them completely, and factionalism within the church especially continued. Gerhoh of Reichersberg believed that the emperor now had the right to request German bishops pay homage to him, something that would never have been allowed under Paschal, due to the vague clause instructing newly-elects to the things the emperor wished. Gerhoh argued that now imperial intervention in episcopal elections had been curtailed, Henry would use this clause to extend his influence in the church by means of homage. Gerhoh was torn between viewing the concordat as the end of a long struggle between pope and empire, or whether it marked the beginning of a new one within the church itself. Likewise Adelbert of Mainz---who had casually criticised the agreement in his report to Calixtus---continued to lobby against it, and continued to bring complaints against Henry, whom, for example, he alleged had illegally removed the Bishop of Strassburg who was suspected of complicity in the death of Duke Berthold of Zaehringen.
The reformist party within the church took a similar view, criticising the Concordat for failing to remove all secular influence on the church. For this reason, a group of followers of Paschal II unsuccessfully attempted to prevent the agreement\'s ratification at the Lateran Council, crying *non placet!* when asked to do so: \"it was only when it was pointed out that much had to be accepted for the sake of peace that the atmosphere quietened\". Calixtus told them that they had \"not to approve but tolerate\" it. At a council in Bamberg in 1122 Henry gathered those nobles who had not attended the Concordat to seek their approval of the agreement, which they did. The following month he sent cordial letters to Calixtus agreeing with the pope\'s position that as brothers in Christ they were bound by God to work together, etc., and that he would soon visit personally to discuss the repatriation of papal land. These letters were, in turn, responded to positively by Calixtus, who instructed his delegates to make good the promises they had made at Worms.
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# Concordat of Worms
## Reception
### Historiography
`{{Catholic Church sidebar}}`{=mediawiki} Gottfried Wilhelm Leibniz called the agreements made at Worms \"the oldest concordat in German history, an international treaty\", while Augustin Fliche argued that the Concordat effectively instituted the statutes of Ivo of Chartres, a prominent reformer in the early years of the Investiture Contest, a view, it has been suggested, that most historians agree with. The historian Uta-Renate Blumenthal writes that, despite its shortcomings, the Concordat freed \"\[the church and the Empire\] from antiquated concepts with their increasingly anachronistic restrictions\". According to the historian William Chester Jordan, the Concordat was \"of enormous significance\" because it demonstrated that the emperor, in spite of his great secular power, did not have any religious authority. On the other hand, argues Karl F. Morrison, any victory the papacy felt it had won was pyrrhic, as \"the king was left in possession of the field\". The new peace also now allowed the papacy to expand its territories in Italy, such as the Sabina, which were unobtainable while the dispute with Henry was ongoing, while in Germany, a new class of ecclesiastics was created, what Horst Fuhrmann calls the \"ecclesiastical princes of the Empire\".
While most historians agree that the Concordat marks a clear close to the fifty-year-old struggle between church and empire, disagreement continues on just how decisive a termination that was. Historians are also unclear as to the commitment of the pope to the concordat. Stroll, for example, notes that, while Henry\'s oaths were made to the church corporate, so in perpetuity, while Calixtus\'s may have been in a personal capacity. This, Stroll argues, would mean that it could be argued that while Henry\'s commitments to the church applied forever, Calixtus\'s applied only for the duration of Henry\'s reign, and at least one contemporary, Otto of Freising, wrote later in the century that he believed this to be the church\'s position. Stroll considers it \"implausible\" that Henry and his counsel would ever have entered into such a one-sided agreement. Indeed, John O\'Malley has argued that the emperor had effectively been granted a veto from Calixtus; while in the strictest interpretation of the Gregorian reformers the only two important things in the making of a bishop were his election and consecration, Calixtus had effectively codified a role---however small---for the emperor in this process. Conversely, Benson reckons that while Henry\'s agreement was with the church in perpetuity, Calixtus\'---based on the personal mode of address---was with him personally, and as such not binding on his successors. However, this was also an acknowledgement, he suggests, that much of what the pope did not address was already considered customary, and so did not need addressing.
There has also been disagreement in why the Investiture contest ended with the Concordat as it did. Benson notes that, as a truce, it was primarily intended to stop the fighting rather than to address its original causes. It was \"a straightforward, political engagement\... a pragmatic agreement\" between two political bodies. Indeed, controversy over investiture continued for at least another decade; in that light, suggests Benson, it could be argued that the Concordat did not end the dispute at all. There were \"many problems unsolved, and \[it\] left much room for the free play of power\". Political scientist Bruce Bueno de Mesquita has argued that, in the long term, the Concordat was an essential component to the later---gradual---creation of the European nation state
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# Context-free language
In formal language theory, a **context-free language** (**CFL**), also called a **Chomsky type-2 language**, is a language generated by a context-free grammar (CFG).
Context-free languages have many applications in programming languages, in particular, most arithmetic expressions are generated by context-free grammars.
## Background
### Context-free grammar {#context_free_grammar}
Different context-free grammars can generate the same context-free language. Intrinsic properties of the language can be distinguished from extrinsic properties of a particular grammar by comparing multiple grammars that describe the language.
### Automata
The set of all context-free languages is identical to the set of languages accepted by pushdown automata, which makes these languages amenable to parsing. Further, for a given CFG, there is a direct way to produce a pushdown automaton for the grammar (and thereby the corresponding language), though going the other way (producing a grammar given an automaton) is not as direct.
## Examples
An example context-free language is $L = \{a^nb^n:n\geq1\}$, the language of all non-empty even-length strings, the entire first halves of which are `{{mvar|a}}`{=mediawiki}\'s, and the entire second halves of which are `{{mvar|b}}`{=mediawiki}\'s. `{{mvar|L}}`{=mediawiki} is generated by the grammar $S\to aSb ~|~ ab$. This language is not regular. It is accepted by the pushdown automaton $M=(\{q_0,q_1,q_f\}, \{a,b\}, \{a,z\}, \delta, q_0, z, \{q_f\})$ where $\delta$ is defined as follows:
$$\begin{align}
\delta(q_0, a, z) &= (q_0, az) \\
\delta(q_0, a, a) &= (q_0, aa) \\
\delta(q_0, b, a) &= (q_1, \varepsilon) \\
\delta(q_1, b, a) &= (q_1, \varepsilon) \\
\delta(q_1, \varepsilon, z) &= (q_f, \varepsilon)
\end{align}$$
Unambiguous CFLs are a proper subset of all CFLs: there are inherently ambiguous CFLs. An example of an inherently ambiguous CFL is the union of $\{a^n b^m c^m d^n | n, m > 0\}$ with $\{a^n b^n c^m d^m | n, m > 0\}$. This set is context-free, since the union of two context-free languages is always context-free. But there is no way to unambiguously parse strings in the (non-context-free) subset $\{a^n b^n c^n d^n | n > 0\}$ which is the intersection of these two languages.
### Dyck language {#dyck_language}
The language of all properly matched parentheses is generated by the grammar $S\to SS ~|~ (S) ~|~ \varepsilon$.
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# Context-free language
## Properties
### Context-free parsing {#context_free_parsing}
The context-free nature of the language makes it simple to parse with a pushdown automaton.
Determining an instance of the membership problem; i.e. given a string $w$, determine whether $w \in L(G)$ where $L$ is the language generated by a given grammar $G$; is also known as *recognition*. Context-free recognition for Chomsky normal form grammars was shown by Leslie G. Valiant to be reducible to Boolean matrix multiplication, thus inheriting its complexity upper bound of *O*(*n*^2.3728596^). Conversely, Lillian Lee has shown *O*(*n*^3−ε^) Boolean matrix multiplication to be reducible to *O*(*n*^3−3ε^) CFG parsing, thus establishing some kind of lower bound for the latter.
Practical uses of context-free languages require also to produce a derivation tree that exhibits the structure that the grammar associates with the given string. The process of producing this tree is called *parsing*. Known parsers have a time complexity that is cubic in the size of the string that is parsed.
Formally, the set of all context-free languages is identical to the set of languages accepted by pushdown automata (PDA). Parser algorithms for context-free languages include the CYK algorithm and Earley\'s Algorithm.
A special subclass of context-free languages are the deterministic context-free languages which are defined as the set of languages accepted by a deterministic pushdown automaton and can be parsed by a LR(k) parser.
See also parsing expression grammar as an alternative approach to grammar and parser.
### Closure properties {#closure_properties}
The class of context-free languages is closed under the following operations. That is, if *L* and *P* are context-free languages, the following languages are context-free as well:
- the union $L \cup P$ of *L* and *P*
- the reversal of *L*
- the concatenation $L \cdot P$ of *L* and *P*
- the Kleene star $L^*$ of *L*
- the image $\varphi(L)$ of *L* under a homomorphism $\varphi$
- the image $\varphi^{-1}(L)$ of *L* under an inverse homomorphism $\varphi^{-1}$
- the circular shift of *L* (the language $\{vu : uv \in L \}$)
- the prefix closure of *L* (the set of all prefixes of strings from *L*)
- the quotient *L*/*R* of *L* by a regular language *R*
#### Nonclosure under intersection, complement, and difference {#nonclosure_under_intersection_complement_and_difference}
The context-free languages are not closed under intersection. This can be seen by taking the languages $A = \{a^n b^n c^m \mid m, n \geq 0 \}$ and $B = \{a^m b^n c^n \mid m,n \geq 0\}$, which are both context-free. Their intersection is $A \cap B = \{ a^n b^n c^n \mid n \geq 0\}$, which can be shown to be non-context-free by the pumping lemma for context-free languages. As a consequence, context-free languages cannot be closed under complementation, as for any languages *A* and *B*, their intersection can be expressed by union and complement: $A \cap B = \overline{\overline{A} \cup \overline{B}}$. In particular, context-free language cannot be closed under difference, since complement can be expressed by difference: $\overline{L} = \Sigma^* \setminus L$.
However, if *L* is a context-free language and *D* is a regular language then both their intersection $L\cap D$ and their difference $L\setminus D$ are context-free languages.
### Decidability
In formal language theory, questions about regular languages are usually decidable, but ones about context-free languages are often not. It is decidable whether such a language is finite, but not whether it contains every possible string, is regular, is unambiguous, or is equivalent to a language with a different grammar.
The following problems are undecidable for arbitrarily given context-free grammars A and B:
- Equivalence: is $L(A)=L(B)$?
- Disjointness: is $L(A) \cap L(B) = \emptyset$ ? However, the intersection of a context-free language and a *regular* language is context-free, hence the variant of the problem where *B* is a regular grammar is decidable (see \"Emptiness\" below).
- Containment: is $L(A) \subseteq L(B)$ ? Again, the variant of the problem where *B* is a regular grammar is decidable, while that where *A* is regular is generally not.
- Universality: is $L(A)=\Sigma^*$?
- Regularity: is $L(A)$ a regular language?
- Ambiguity: is every grammar for $L(A)$ ambiguous?
The following problems are *decidable* for arbitrary context-free languages:
- Emptiness: Given a context-free grammar *A*, is $L(A) = \emptyset$ ?
- Finiteness: Given a context-free grammar *A*, is $L(A)$ finite?
- Membership: Given a context-free grammar *G*, and a word $w$, does $w \in L(G)$ ? Efficient polynomial-time algorithms for the membership problem are the CYK algorithm and Earley\'s Algorithm.
According to Hopcroft, Motwani, Ullman (2003), many of the fundamental closure and (un)decidability properties of context-free languages were shown in the 1961 paper of Bar-Hillel, Perles, and Shamir
### Languages that are not context-free {#languages_that_are_not_context_free}
The set $\{a^n b^n c^n d^n | n > 0\}$ is a context-sensitive language, but there does not exist a context-free grammar generating this language. So there exist context-sensitive languages which are not context-free. To prove that a given language is not context-free, one may employ the pumping lemma for context-free languages or a number of other methods, such as Ogden\'s lemma or Parikh\'s theorem
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# Clitoris
In amniotes, the **clitoris** (`{{IPAc-en|audio=Clitoris pronunciation 1.ogg|ˈ|k|l|ɪ|t|ər|ɪ|s}}`{=mediawiki} `{{respell|KLIT|ər|iss}}`{=mediawiki} or `{{IPAc-en|audio=Clitoris pronunciation 2.ogg|k|l|ɪ|ˈ|t|ɔər|ɪ|s}}`{=mediawiki} `{{respell|klih|TOR|iss}}`{=mediawiki}; `{{plural form}}`{=mediawiki}: **clitorises** or **clitorides**) is a female sex organ. In humans, it is the vulva\'s most erogenous area and generally the primary anatomical source of female sexual pleasure. The clitoris is a complex structure, and its size and sensitivity can vary. The visible portion, the glans, of the clitoris is typically roughly the size and shape of a pea and is estimated to have at least 8,000 nerve endings.
-
- Peters, B; Uloko, M; Isabey, P; [How many Nerve Fibers Innervate the Human Clitoris? A Histomorphometric Evaluation of the Dorsal Nerve of the Clitoris](https://www1.statusplus.net/misc/prog-management/v2/general/abstract/5850?persons=4928&pm=23) `{{Webarchive|url=https://web.archive.org/web/20221102083626/https://www1.statusplus.net/misc/prog-management/v2/general/abstract/5850?persons=4928&pm=23 |date=2 November 2022 }}`{=mediawiki} 2 p.m. ET 27 October 2022, 23rd annual joint scientific meeting of Sexual Medicine Society of North America and International Society for Sexual Medicine
Sexological, medical, and psychological debate has focused on the clitoris, and it has been subject to social constructionist analyses and studies. Such discussions range from anatomical accuracy, gender inequality, female genital mutilation, and orgasmic factors and their physiological explanation for the G-spot. The only known purpose of the human clitoris is to provide sexual pleasure.
Knowledge of the clitoris is significantly affected by its cultural perceptions. Studies suggest that knowledge of its existence and anatomy is scant in comparison with that of other sexual organs (especially male sex organs) and that more education about it could help alleviate stigmas, such as the idea that the clitoris and vulva in general are visually unappealing or that female masturbation is taboo and disgraceful.
The clitoris is homologous to the penis in males.
## Etymology and terminology {#etymology_and_terminology}
The Oxford English Dictionary states that the Neo-Latin word *clītoris* likely has its origin in the Ancient Greek *κλειτορίς* (`{{Transliteration|grc|kleitorís}}`{=mediawiki}), which means \"little hill\", and perhaps derived from the verb *κλείειν* (`{{Transliteration|grc|kleíein}}`{=mediawiki}), meaning \"to shut\" or \"to sheathe\". *Clitoris* is also related to the Greek word *κλείς* (`{{Transliteration|grc|kleís}}`{=mediawiki}), \"key\", \"indicating that the ancient anatomists considered it the key\" to female sexuality. In addition, the Online Etymology Dictionary suggests other Greek candidates for this word\'s etymology include a noun meaning \"latch\" or \"hook\" or a verb meaning \"to touch or titillate lasciviously\", \"to tickle\". The Oxford English Dictionary also states that the colloquially shortened form *clit*, the first occurrence of which was noted in the United States, has been used in print since 1958: until then, the common abbreviation was *clitty*. Other slang terms for clitoris are *bean*, *nub*, and *love button*. The term `{{em|clitoris}}`{=mediawiki} is commonly used to refer to the glans alone. In recent anatomical works, the clitoris has also been referred to as the **bulbo-clitoral organ**.
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# Clitoris
## Structure
Most of the clitoris is composed of internal parts. Regarding humans, it consists of the glans, the body (which is composed of two erectile structures known as the corpora cavernosa), the prepuce, and the root. The frenulum is beneath the glans.
Research indicates that clitoral tissue extends into the vaginal anterior wall. Şenaylı et al. said that the histological evaluation of the clitoris, \"especially of the corpora cavernosa, is incomplete because for many years the clitoris was considered a rudimentary and nonfunctional organ\". They added that Baskin and colleagues examined the clitoris\' masculinization after dissection and using imaging software after Masson\'s trichrome staining, put the serial dissected specimens together; this revealed that nerves surround the whole clitoral body.
The clitoris, its bulbs, labia minora, and urethra involve two histologically distinct types of vascular tissue (tissue related to blood vessels), the first of which is trabeculated, erectile tissue innervated by the cavernous nerves. The trabeculated tissue has a spongy appearance; along with blood, it fills the large, dilated vascular spaces of the clitoris and the bulbs. Beneath the epithelium of the vascular areas is smooth muscle. As indicated by Yang et al.\'s research, it may also be that the urethral lumen (the inner open space or cavity of the urethra), which is surrounded by a spongy tissue, has tissue that \"is grossly distinct from the vascular tissue of the clitoris and bulbs, and on macroscopic observation, is paler than the dark tissue\" of the clitoris and bulbs. The second type of vascular tissue is non-erectile, which may consist of blood vessels that are dispersed within a fibrous matrix and have only a minimal amount of smooth muscle.
### Glans
Highly innervated, the **clitoral glans** (*glans* means \"acorn\" in Latin), also known as the \"head\" or \"tip\", exists at the top of the clitoral body as a fibro-vascular cap and is usually the size and shape of a pea, although it is sometimes much larger or smaller. The glans is separated from the clitoral body by a ridge of tissue called the *corona*. The clitoral glans is estimated to have 8,000 and possibly 10,000 or more sensory nerve endings, making it the most sensitive erogenous zone. The glans also has numerous genital corpuscles. Research conflicts on whether the glans is composed of erectile or non-erectile tissue. Some sources describe the clitoral glans and labia minora as composed of non-erectile tissue; this is especially the case for the glans. They state that the clitoral glans and labia minora have blood vessels that are dispersed within a fibrous matrix and have only a minimal amount of smooth muscle, or that the clitoral glans is \"a midline, densely neural, non-erectile structure\". The clitoral glans is homologous to the male penile glans.
Other descriptions of the glans assert that it is composed of erectile tissue and that erectile tissue is present within the labia minora. The glans may be noted as having glandular vascular spaces that are not as prominent as those in the clitoral body, with the spaces being separated more by smooth muscle than in the body and crura. Adipose tissue is absent in the labia minora, but the organ may be described as being made up of dense connective tissue, erectile tissue and elastic fibers.
### Frenulum
The **clitoral frenulum** or **frenum** (***frenulum clitoridis**\'\' and***crus glandis clitoridis**\'\' in Latin; the former meaning \"little bridle\") is a medial band of tissue formed between the undersurface of the glans and the top ends of the labia minora. It is homologous to the penile frenulum in males. The frenulum\'s main function is to maintain the clitoris in its innate position.
### Body
The **clitoral body** (also known as the **shaft of the clitoris**) is a portion behind the glans that contains the union of the corpora cavernosa, a pair of sponge-like regions of erectile tissue that hold most of the blood in the clitoris during erection. It is homologous to the penile shaft in the male. The two corpora forming the clitoral body are surrounded by thick fibro-elastic tunica albuginea, a sheath of connective tissue. These corpora are separated incompletely from each other in the midline by a fibrous pectiniform septum`{{snds}}`{=mediawiki}a comblike band of connective tissue extending between the corpora cavernosa. The clitoral body is also connected to the pubic symphysis by the suspensory ligament.
The body of the clitoris is a bent shape, which makes the clitoral angle or elbow. The angle divides the body into the ascending part (internal) near the pubic symphysis and the descending part (external), which can be seen and felt through the clitoral hood.
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# Clitoris
## Structure
### Root
Lying in the perineum (space between the vulva and anus) and within the superficial perineal pouch is the **root of the clitoris**, which consists of the posterior ends of the clitoris, the crura and the bulbs of vestibule.
The crura (\"legs\") are the parts of the corpora cavernosa extending from the clitoral body and form an upside-down \"V\" shape. Each crus (singular form of crura) is attached to the corresponding ischial ramus`{{snds}}`{=mediawiki}extensions of the corpora beneath the descending pubic rami. Concealed behind the labia minora, the crura end with attachment at or just below the middle of the pubic arch.`{{refn|"The long, narrow crura arise from the inferior surface of the ischiopubic rami and fuse just below the middle of the pubic arch."<ref name="Cunningham" />|group="N"|name="quote_Cunningham"}}`{=mediawiki} Associated are the urethral sponge, perineal sponge, a network of nerves and blood vessels, the suspensory ligament of the clitoris, muscles and the pelvic floor.
The vestibular bulbs are more closely related to the clitoris than the vestibule because of the similarity of the trabecular and erectile tissue within the clitoris and its bulbs, and the absence of trabecular tissue in other parts of the vulva, with the erectile tissue\'s trabecular nature allowing engorgement and expansion during sexual arousal. The vestibular bulbs are typically described as lying close to the crura on either side of the vaginal opening; internally, they are beneath the labia majora. The anterior sections of the bulbs unite to create the bulbar commissure, which forms a long strip of erectile tissue dubbed the infra-corporeal residual spongy part (RSP) that expands from the ventral shaft and terminates as the glans. The RSP is also connected to the shaft via the pars intermedia (venous plexus of Kobelt). When engorged with blood, the bulbs cuff the vaginal opening and cause the vulva to expand outward. Although several texts state that they surround the vaginal opening, Ginger et al. state that this does not appear to be the case and tunica albuginea does not envelop the erectile tissue of the bulbs. In Yang et al.\'s assessment of the bulbs\' anatomy, they conclude that the bulbs \"arch over the distal urethra, outlining what might be appropriately called the \'bulbar urethra\' in women\".
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# Clitoris
## Structure
### Hood
The clitoral hood or prepuce projects at the front of the labia commissure, where the edges of the labia majora meet at the base of the pubic mound. It is partially formed by fusion of the upper labia minora. The hood\'s function is to cover and protect the glans and external shaft. There is considerable variation in how much of the glans protrudes from the hood and how much is covered by it, ranging from completely covered to fully exposed, and tissue of the labia minora also encircles the base of the glans.
### Size and length {#size_and_length}
There is no identified correlation between the size of the glans or clitoris as a whole, and a woman\'s age, height, weight, use of hormonal contraception, or being postmenopausal, although women who have given birth may have significantly larger clitoral measurements. Centimetre and millimetre measurements of the clitoris show variations in size. The clitoral glans has been cited as typically varying from 2 mm to 1 cm (less than an inch) and usually being estimated at 4 to 5 mm in both the transverse and longitudinal planes.
A 1992 study concluded that the total clitoral length, including glans and body, is 16.0 +/-, where 16 mm is the mean and 4.3 mm is the standard deviation. Concerning other studies, researchers from the Elizabeth Garrett Anderson and Obstetric Hospital in London measured the labia and other genital structures of 50 women from the age of 18 to 50, with a mean age of 35.6., from 2003 to 2004, and the results given for the clitoral glans were 3`{{ndash}}`{=mediawiki}10 mm for the range and 5.5 \[1.7\] mm for the mean. Other research indicates that the clitoral body can measure 5 - in length, while the clitoral body and crura together can be 10 cm or more in length.
## Development
The clitoris develops from a phallic outgrowth in the embryo called the genital tubercle. In the absence of testosterone, the genital tubercle allows for the formation of the clitoris; the initially rapid growth of the phallus gradually slows and the body and glans of the clitoris are formed along with its other structures.
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# Clitoris
## Function
### Sexual stimulation and arousal {#sexual_stimulation_and_arousal}
The clitoris has an abundance of nerve endings, and is the human female\'s most erogenous part of the body. When sexually stimulated, it may incite sexual arousal, which may result from mental stimulation (sexual fantasy), activity with a sexual partner, or masturbation, and can lead to orgasm. The most effective sexual stimulation of this organ is usually manually or orally, which is often referred to as direct clitoral stimulation; in cases involving sexual penetration, these activities may also be referred to as additional or assisted clitoral stimulation.
Direct stimulation involves physical stimulation to the external anatomy of the clitoris`{{snds}}`{=mediawiki}glans, hood, and shaft. Stimulation of the labia minora, due to it being connected with the glans and hood, may have the same effect as direct clitoral stimulation. Though these areas may also receive indirect physical stimulation during sexual activity, such as when in friction with the labia majora, indirect clitoral stimulation is more commonly attributed to penile-vaginal penetration. Penile-anal penetration may also indirectly stimulate the clitoris by the shared sensory nerves (especially the pudendal nerve, which gives off the inferior anal nerves and divides into two terminal branches: the perineal nerve and the dorsal nerve of the clitoris).
Due to the glans\' high sensitivity, direct stimulation to it is not always pleasurable; instead, direct stimulation to the hood or near the glans is often more pleasurable, with the majority of women preferring to use the hood to stimulate the glans, or to have the glans rolled between the labia, for indirect touch. It is also common for women to enjoy the shaft being softly caressed in concert with the occasional circling of the glans. This might be with or without digital penetration of the vagina, while other women enjoy having the entire vulva caressed. As opposed to the use of dry fingers, stimulation from well-lubricated fingers, either by vaginal lubrication or a personal lubricant, is usually more pleasurable for the external clitoris.
As the clitoris\' external location does not allow for direct stimulation by penetration, any external clitoral stimulation while in the missionary position usually results from the pubic bone area. As such, some couples may engage in the woman-on-top position or the coital alignment technique, a sex position combining the \"riding high\" variation of the missionary position with pressure-counterpressure movements performed by each partner in rhythm with sexual penetration, to maximize clitoral stimulation. Same-sex female couples may engage in tribadism (vulva-to-vulva or vulva-to-body rubbing) for ample or mutual clitoral stimulation during whole-body contact.`{{refn|"A common variation is 'tribadism,' where two women lie face to face, one on top of the other. The genitals are pressed tightly together while the partners move in a grinding motion. Some rub their clitoris against their partner's pubic bone."<ref name="Westheimer" />|group="N"|name="quote_Westheimer"}}`{=mediawiki} Pressing the penis in a gliding or circular motion against the clitoris or stimulating it by the movement against another body part may also be practiced. A vibrator (such as a clitoral vibrator), dildo or other sex toy may be used. Other women stimulate the clitoris by use of a pillow or other inanimate object, by a jet of water from the faucet of a bathtub or shower, or by closing their legs and rocking.
During sexual arousal, the clitoris and the rest of the vulva engorge and change color as the erectile tissues fill with blood (vasocongestion), and the individual experiences vaginal contractions. The ischiocavernosus and bulbocavernosus muscles, which insert into the corpora cavernosa, contract and compress the dorsal vein of the clitoris (the only vein that drains the blood from the spaces in the corpora cavernosa), and the arterial blood continues a steady flow and having no way to drain out, fills the venous spaces until they become turgid and engorged with blood. This is what leads to clitoral erection.
The prepuce has retracted and the glans becomes more visible. The glans doubles in diameter upon arousal and further stimulation becomes less visible as it is covered by the swelling of the clitoral hood. The swelling protects the glans from direct contact, as direct contact at this stage can be more irritating than pleasurable. Vasocongestion eventually triggers a muscular reflex, which expels the blood that was trapped in surrounding tissues, and leads to an orgasm. A short time after stimulation has stopped, especially if orgasm has been achieved, the glans becomes visible again and returns to its normal state, with a few seconds (usually 5`{{ndash}}`{=mediawiki}10) to return to its normal position and 5`{{ndash}}`{=mediawiki}10 minutes to return to its original size.`{{refn|"Within a few seconds the clitoris returns to its normal position, and after 5{{ndash}}10 minutes shrinks to its normal size."<ref name="Dennerstein" />|group="N"|name="quote_Dennerstein"}}`{=mediawiki} If orgasm is not achieved, the clitoris may remain engorged for a few hours, which women often find uncomfortable. Additionally, the clitoris is very sensitive after orgasm, making further stimulation initially painful for some women.
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# Clitoris
## Function
### Sexual stimulation and arousal {#sexual_stimulation_and_arousal}
#### Clitoral and vaginal orgasmic factors {#clitoral_and_vaginal_orgasmic_factors}
General statistics indicate that 70`{{ndash}}`{=mediawiki}80 percent of women require direct clitoral stimulation (consistent manual, oral, or other concentrated friction against the external parts of the clitoris) to reach orgasm.`{{refn|"Most women report the inability to achieve orgasm with vaginal intercourse and require direct clitoral stimulation ... About 20% have coital climaxes ..."<ref name="Kammerer-Doak" />|group="N"|name="quote_Kammerer-Doak"}}`{=mediawiki}`{{refn|"Women rated clitoral stimulation as at least somewhat more important than vaginal stimulation in achieving orgasm; only about 20% indicated that they did not require additional clitoral stimulation during intercourse."<ref name="Mah" />|group="N"|name="quote_Mah"}}`{=mediawiki}`{{refn|"a. The amount of time of sexual arousal needed to reach orgasm is variable – and usually much longer – in women than in men; thus, only 20–30% of women attain a coital climax. b. Many women (70–80%) require manual clitoral stimulation ..."<ref name="Flaherty" />|group="N"|name="quote_Flaherty"}}`{=mediawiki} Indirect clitoral stimulation (for example, by means of vaginal penetration) may also be sufficient for female orgasm.`{{refn|"In sum, it seems that approximately 25% of women always have orgasm with intercourse, while a narrow majority of women have orgasm with intercourse more than half the time ... According to the general statistics, cited in Chapter 2, [women who can consistently and easily have orgasms during unassisted intercourse] represent perhaps 20% of the adult female population, and thus cannot be considered representative."<ref name="Lloyd pp21-53" />|group="N"|name="quote_Lloyd"}}`{=mediawiki} The area near the entrance of the vagina (the lower third) contains nearly 90 percent of the vaginal nerve endings, and there are areas in the anterior vaginal wall and between the top junction of the labia minora and the urinary meatus that are especially sensitive, but intense sexual pleasure, including orgasm, solely from vaginal stimulation is occasional or otherwise absent because the vagina has significantly fewer nerve endings than the clitoris.
The prominent debate over the quantity of vaginal nerve endings began with Alfred Kinsey. Although Sigmund Freud\'s theory that clitoral orgasms are a prepubertal or adolescent phenomenon and that vaginal (or G-spot) orgasms are something that only physically mature females experience had been criticized before, Kinsey was the first researcher to harshly criticize the theory. Through his observations of female masturbation and interviews with thousands of women, Kinsey found that most of the women he observed and surveyed could not have vaginal orgasms, a finding that was also supported by his knowledge of sex organ anatomy. Scholar Janice M. Irvine stated that he \"criticized Freud and other theorists for projecting male constructs of sexuality onto women\" and \"viewed the clitoris as the main center of sexual response\". He considered the vagina to be \"relatively unimportant\" for sexual satisfaction, relaying that \"few women inserted fingers or objects into their vaginas when they masturbated\". Believing that vaginal orgasms are \"a physiological impossibility\" because the vagina has insufficient nerve endings for sexual pleasure or climax, he \"concluded that satisfaction from penile penetration \[is\] mainly psychological or perhaps the result of referred sensation\".
Masters and Johnson\'s research, as well as Shere Hite\'s, generally supported Kinsey\'s findings about the female orgasm. Masters and Johnson were the first researchers to determine that the clitoral structures surround and extend along and within the labia. They observed that both clitoral and vaginal orgasms have the same stages of physical response, and found that the majority of their subjects could only achieve clitoral orgasms, while a minority achieved vaginal orgasms. On that basis, they argued that clitoral stimulation is the source of both kinds of orgasms, reasoning that the clitoris is stimulated during penetration by friction against its hood. The research came at the time of the second-wave feminist movement, which inspired feminists to reject the distinction made between clitoral and vaginal orgasms. Feminist Anne Koedt argued that because men \"have orgasms essentially by friction with the vagina\" and not the clitoral area, this is why women\'s biology had not been properly analyzed. \"Today, with extensive knowledge of anatomy, with \[C. Lombard Kelly\], Kinsey, and Masters and Johnson, to mention just a few sources, there is no ignorance on the subject \[of the female orgasm\]\", she stated in her 1970 article *The Myth of the Vaginal Orgasm.* She added, \"There are, however, social reasons why this knowledge has not been popularized. We are living in a male society which has not sought change in women\'s role\".
Supporting an anatomical relationship between the clitoris and vagina is a study published in 2005, which investigated the size of the clitoris; Australian urologist Helen O\'Connell, described as having initiated discourse among mainstream medical professionals to refocus on and redefine the clitoris, noted a direct relationship between the legs or roots of the clitoris and the erectile tissue of the bulbs and corpora, and the distal urethra and vagina while using magnetic resonance imaging (MRI) technology. While some studies, using ultrasound, have found physiological evidence of the G-spot in women who report having orgasms during vaginal intercourse, O\'Connell argues that this interconnected relationship is the physiological explanation for the conjectured G-spot and experience of vaginal orgasms, taking into account the stimulation of the internal parts of the clitoris during vaginal penetration. \"The vaginal wall is, in fact, the clitoris\", she said. \"If you lift the skin off the vagina on the side walls, you get the bulbs of the clitoris`{{snds}}`{=mediawiki}triangular, crescental masses of erectile tissue\". O\'Connell et al., having performed dissections on the vulvas of cadavers and used photography to map the structure of nerves in the clitoris, made the assertion in 1998 that there is more erectile tissue associated with the clitoris than is generally described in anatomical textbooks and were thus already aware that the clitoris is more than just its glans. They concluded that some females have more extensive clitoral tissues and nerves than others, especially having observed this in young cadavers compared to elderly ones, and therefore whereas the majority of females can only achieve orgasm by direct stimulation of the external parts of the clitoris, the stimulation of the more generalized tissues of the clitoris via vaginal intercourse may be sufficient for others.
French researchers Odile Buisson and Pierre Foldès reported similar findings to that of O\'Connell\'s. In 2008, they published the first complete 3D sonography of the stimulated clitoris and republished it in 2009 with new research, demonstrating how erectile tissue of the clitoris engorges and surrounds the vagina. Based on their findings, they argued that women may be able to achieve vaginal orgasm through stimulation of the G-spot because the clitoris is pulled closely to the anterior wall of the vagina when the woman is sexually aroused and during vaginal penetration. They assert that since the front wall of the vagina is inextricably linked with the internal parts of the clitoris, stimulating the vagina without activating the clitoris may be next to impossible. In their 2009 published study, it states the \"coronal planes during perineal contraction and finger penetration demonstrated a close relationship between the root of the clitoris and the anterior vaginal wall\". Buisson and Foldès suggested \"that the special sensitivity of the lower anterior vaginal wall could be explained by pressure and movement of clitoris\' root during a vaginal penetration and subsequent perineal contraction\".
Researcher Vincenzo Puppo, who, while agreeing that the clitoris is the center of female sexual pleasure and believing that there is no anatomical evidence of the vaginal orgasm, disagrees with O\'Connell and other researchers\' terminological and anatomical descriptions of the clitoris (such as referring to the vestibular bulbs as the \"clitoral bulbs\") and states that \"the inner clitoris\" does not exist because the penis cannot come in contact with the congregation of multiple nerves/veins situated until the angle of the clitoris, detailed by Georg Ludwig Kobelt, or with the root of the clitoris, which does not have sensory receptors or erogenous sensitivity, during vaginal intercourse. Puppo\'s belief contrasts the general belief among researchers that vaginal orgasms are the result of clitoral stimulation; they reaffirm that clitoral tissue extends, or is at least stimulated by its bulbs, even in the area most commonly reported to be the G-spot.
The G-spot is analogous to the base of the penis and has additionally been theorized, with the sentiment from researcher Amichai Kilchevsky that because female fetal development is the \"default\" state in the absence of substantial exposure to male hormones and therefore the penis is essentially a clitoris enlarged by such hormones, there is no evolutionary reason why females would have an entity in addition to the clitoris that can produce orgasms. The general difficulty of achieving orgasms vaginally, which is a predicament that is likely due to nature easing the process of childbearing by drastically reducing the number of vaginal nerve endings, challenge arguments that vaginal orgasms help encourage sexual intercourse to facilitate reproduction. Supporting a distinct G-spot, however, is a study by Rutgers University, published in 2011, which was the first to map the female genitals onto the sensory portion of the brain; the scans indicated that the brain registered distinct feelings between stimulating the clitoris, the cervix and the vaginal wall`{{snds}}`{=mediawiki}where the G-spot is reported to be`{{snds}}`{=mediawiki}when several women stimulated themselves in a functional magnetic resonance machine. Barry Komisaruk, head of the research findings, stated that he feels that \"the bulk of the evidence shows that the G-spot is not a particular thing\" and that it is \"a region, it\'s a convergence of many different structures\".
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## Function
### Vestigiality, adaptionist and reproductive views {#vestigiality_adaptionist_and_reproductive_views}
Whether the clitoris is vestigial, an adaptation, or serves a reproductive function has been debated. Geoffrey Miller stated that Helen Fisher, Meredith Small and Sarah Blaffer Hrdy \"have viewed the clitoral orgasm as a legitimate adaptation in its own right, with major implications for female sexual behavior and sexual evolution\". Like Lynn Margulis and Natalie Angier, Miller believes, \"The human clitoris shows no apparent signs of having evolved directly through male mate choice. It is not especially large, brightly colored, specifically shaped or selectively displayed during courtship\". He contrasts this with other female species that have clitorises as long as their male counterparts. He said the human clitoris \"could have evolved to be much more conspicuous if males had preferred sexual partners with larger brighter clitorises\" and that \"its inconspicuous design combined with its exquisite sensitivity suggests that the clitoris is important not as an object of male mate choice, but as a mechanism of female choice\".
While Miller stated that male scientists such as Stephen Jay Gould and Donald Symons \"have viewed the female clitoral orgasm as an evolutionary side-effect of the male capacity for penile orgasm\" and that they \"suggested that clitoral orgasm cannot be an adaptation because it is too hard to achieve\", Gould acknowledged that \"most female orgasms emanate from a clitoral, rather than vaginal (or some other), site\" and that his nonadaptive belief \"has been widely misunderstood as a denial of either the adaptive value of female orgasm in general or even as a claim that female orgasms lack significance in some broader sense\". He said that although he accepts that \"clitoral orgasm plays a pleasurable and central role in female sexuality and its joys\", \"\[a\]ll these favorable attributes, however, emerge just as clearly and just as easily, whether the clitoral site of orgasm arose as a spandrel or an adaptation\". He added that the \"male biologists who fretted over \[the adaptionist questions\] simply assumed that a deeply vaginal site, nearer the region of fertilization, would offer greater selective benefit\" due to their Darwinian, *summum bonum* beliefs about enhanced reproductive success.
Similar to Gould\'s beliefs about adaptionist views and that \"females grow nipples as adaptations for suckling, and males grow smaller unused nipples as a spandrel based upon the value of single development channels\", American philosopher Elisabeth Lloyd suggested that there is little evidence to support an adaptionist account of female orgasm. Canadian sexologist Meredith L. Chivers stated that \"Lloyd views female orgasm as an ontogenetic leftover; women have orgasms because the urogenital neurophysiology for orgasm is so strongly selected for in males that this developmental blueprint gets expressed in females without affecting fitness\" and this is similar to \"males hav\[ing\] nipples that serve no fitness-related function\".
At the 2002 conference for Canadian Society of Women in Philosophy, Nancy Tuana argued that the clitoris is unnecessary in reproduction; she stated that it has been ignored because of \"a fear of pleasure. It is pleasure separated from reproduction. That\'s the fear\". She reasoned that this fear causes ignorance, which veils female sexuality. O\'Connell stated, \"It boils down to rivalry between the sexes: the idea that one sex is sexual and the other reproductive. The truth is that both are sexual and both are reproductive\". She reiterated that the vestibular bulbs appear to be part of the clitoris and that the distal urethra and vagina are intimately related structures, although they are not erectile in character, forming a tissue cluster with the clitoris that appears to be the location of female sexual function and orgasm.
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# Clitoris
## Clinical significance {#clinical_significance}
### Modification
Genital modification may be for aesthetic, medical or cultural reasons. This includes female genital mutilation (FGM), sex reassignment surgery (for trans men as part of transitioning), intersex surgery, and genital piercings. Use of anabolic steroids by bodybuilders and other athletes can result in significant enlargement of the clitoris along with other masculinizing effects on their bodies. Abnormal enlargement of the clitoris may be referred to as *clitoromegaly* or *macroclitoris*, but clitoromegaly is more commonly seen as a congenital anomaly of the genitalia.
Clitoroplasty, a sex reassignment surgery for trans women, involves the construction of a clitoris from penile tissue.
People taking hormones or other medications as part of a gender transition usually experience dramatic clitoral growth; individual desires and the difficulties of phalloplasty (construction of a penis) often result in the retention of the original genitalia with the enlarged clitoris as a penis analog (metoidioplasty). However, the clitoris cannot reach the size of the penis through hormones. A surgery to add function to the clitoris, such as metoidioplasty, is an alternative to phalloplasty that permits the retention of sexual sensation in the clitoris.
In clitoridectomy, the clitoris may be removed as part of a radical vulvectomy to treat cancer such as vulvar intraepithelial neoplasia; however, modern treatments favor more conservative approaches, as invasive surgery can have psychosexual consequences. Clitoridectomy more often involves parts of the clitoris being partially or completely removed during FGM, which may be additionally known as female circumcision or female genital cutting (FGC). Removing the glans does not mean that the whole structure is lost, since the clitoris reaches deep into the genitals.
In reduction clitoroplasty, a common intersex surgery, the glans is preserved and parts of the erectile bodies are excised. Problems with this technique include loss of sensation, loss of sexual function, and sloughing of the glans. One way to preserve the clitoris with its innervations and function is to imbricate and bury the glans; however, Şenaylı et al. state that \"pain during stimulus because of trapped tissue under the scarring is nearly routine. In another method, 50 percent of the ventral clitoris is removed through the level base of the clitoral shaft, and it is reported that good sensation and clitoral function are observed in follow-up\"; additionally, it has \"been reported that the complications are from the same as those in the older procedures for this method\".
Concerning females who have the condition congenital adrenal hyperplasia, the largest group requiring surgical genital correction, researcher Atilla Şenaylı stated, \"The main expectations for the operations are to create a normal female anatomy, with minimal complications and improvement of life quality\". Şenaylı added that \"\[c\]osmesis, structural integrity, the coital capacity of the vagina, and absence of pain during sexual activity are the parameters to be judged by the surgeon\". (Cosmesis usually refers to the surgical correction of a disfiguring defect.) He stated that although \"expectations can be standardized within these few parameters, operative techniques have not yet become homogeneous. Investigators have preferred different operations for different ages of patients\".
Gender assessment and surgical treatment are the two main steps in intersex operations. \"The first treatments for clitoromegaly were simply resection of the clitoris. Later, it was understood that the clitoris glans and sensory input are important to facilitate orgasm\", stated Atilla. The clitoral glans\' epithelium \"has high cutaneous sensitivity, which is important in sexual responses\", and it is because of this that \"recession clitoroplasty was later devised as an alternative, but reduction clitoroplasty is the method currently performed\".
What is often referred to as a \"clitoris piercing\" is the more common (and significantly less complicated) clitoral hood piercing. Since piercing the clitoris is difficult and very painful, piercing the clitoral hood is more common than piercing the clitoral shaft or glans, owing to the small percentage of people who are anatomically suited for it. Clitoral hood piercings are usually channeled in the form of vertical piercings, and, to a lesser extent, horizontal piercings. The triangle piercing is a very deep horizontal hood piercing and is done behind the clitoris as opposed to in front of it. For styles such as the Isabella piercing, which passes through the clitoral shaft but is placed deep at the base, they provide unique stimulation and still require the proper genital build. The Isabella starts between the clitoral glans and the urethra, exiting at the top of the clitoral hood; this piercing is highly risky concerning the damage that may occur because of intersecting nerves. (See Clitoral index.)
### Sexual disorders {#sexual_disorders}
Persistent genital arousal disorder (PGAD) results in spontaneous, persistent, and uncontrollable genital arousal in women, unrelated to any feelings of sexual desire. Clitoral priapism is a rare, potentially painful medical condition and is sometimes described as an aspect of PGAD. With PGAD, arousal lasts for an unusually extended period (ranging from hours to days); it can also be associated with morphometric and vascular modifications of the clitoris.
Drugs may cause or affect clitoral priapism. The drug trazodone is known to cause male priapism as a side effect, but there is only one documented report that it may have caused clitoral priapism, in which case discontinuing the medication may be a remedy. Additionally, nefazodone is documented to have caused clitoral engorgement, as distinct from clitoral priapism, in one case, and clitoral priapism can sometimes start as a result of, or only after, the discontinuation of antipsychotics or selective serotonin reuptake inhibitors (SSRIs).
Because PGAD is relatively rare and, as its concept apart from clitoral priapism, has only been researched since 2001, there is little research into what may cure or remedy the disorder. In some recorded cases, PGAD was caused by or caused, a pelvic arterial-venous malformation with arterial branches to the clitoris; surgical treatment was effective in these cases.
In 2022, an article in *The New York Times* reported several instances of women experiencing reduced clitoral sensitivity or inability to orgasm following various surgical procedures, including biopsies of the vulva, pelvic mesh surgeries (sling surgeries), and labiaplasties. The Times quoted several researchers who suggest that surgeons\' lack of training in clitoral anatomy and nerve distribution may have been a factor.
As it is part of the vulva, the clitoris is susceptible to pain (clitorodynia) from various conditions such as sexually transmitted infections and pudendal nerve entrapment. The clitoris may also be affected by vulvar cancer, although at a much lower rate.
Clitoral phimosis (or clitoral adhesions) is when the prepuce cannot be retracted, limiting exposure of the glans.
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## Clinical significance {#clinical_significance}
### Smegma
The secretion of smegma (smegma clitoridis) comes from the apocrine glands of the clitoris (sweat), the sebaceous glands of the clitoris (sebum) and desquamating epithelial cells.
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## Society and culture {#society_and_culture}
### Ancient Greek--16th century knowledge and vernacular {#ancient_greek16th_century_knowledge_and_vernacular}
Concerning historical and modern perceptions of the clitoris, the clitoris and the penis were considered equivalent by some scholars for more than 2,500 years in all respects except their arrangement. Due to it being frequently omitted from, or misrepresented in, historical and contemporary anatomical texts, it was also subject to a continual cycle of male scholars claiming to have discovered it. The ancient Greeks, ancient Romans, and Greek and Roman generations up to and throughout the Renaissance, were aware that male and female sex organs are anatomically similar, but prominent anatomists such as Galen and Vesalius regarded the vagina as the structural equivalent of the penis, except for being inverted; Vesalius argued against the existence of the clitoris in normal women, and his anatomical model described how the penis corresponds with the vagina, without a role for the clitoris.
Ancient Greek and Roman sexuality additionally designated penetration as \"male-defined\" sexuality. The term *tribas*, or `{{em|tribade}}`{=mediawiki}, was used to refer to a woman or intersex individual who actively penetrated another person (male or female) through the use of the clitoris or a dildo. As any sexual act was believed to require that one of the partners be \"phallic\" and that therefore sexual activity between women was impossible without this feature, mythology popularly associated lesbians with either having enlarged clitorises or as incapable of enjoying sexual activity without the substitution of a phallus.
In 1545, Charles Estienne was the first writer to identify the clitoris in a work based on dissection, but he concluded that it had a urinary function. Following this study, Realdo Colombo (also known as Renaldus Columbus), a lecturer in surgery at the University of Padua, Italy, published a book called *De re anatomica* in 1559, in which he describes the \"seat of woman\'s delight\". In his role as researcher, Colombo concluded, \"Since no one has discerned these projections and their workings, if it is permissible to give names to things discovered by me, it should be called the love or sweetness of Venus.\", about the mythological Venus, goddess of erotic love. Colombo\'s claim was disputed by his successor at Padua, Gabriele Falloppio (discoverer of the fallopian tube), who claimed that he was the first to discover the clitoris. In 1561, Falloppio stated, \"Modern anatomists have entirely neglected it \... and do not say a word about it \... and if others have spoken of it, know that they have taken it from me or my students\". This caused an upset in the European medical community, and, having read Colombo\'s and Falloppio\'s detailed descriptions of the clitoris, Vesalius stated, \"It is unreasonable to blame others for incompetence on the basis of some sport of nature you have observed in some women and you can hardly ascribe this new and useless part, as if it were an organ, to healthy women\". He concluded, \"I think that such a structure appears in hermaphrodites who otherwise have well-formed genitals, as Paul of Aegina describes, but I have never once seen in any woman a penis (which Avicenna called albaratha and the Greeks called an enlarged nympha and classed as an illness) or even the rudiments of a tiny phallus\".
The average anatomist had difficulty challenging Galen\'s or Vesalius\' research; Galen was the most famous physician of the Greek era and his works were considered the standard of medical understanding up to and throughout the Renaissance (i.e. for almost two thousand years), and various terms being used to describe the clitoris seemed to have further confused the issue of its structure. In addition to Avicenna\'s naming it the *albaratha* or *virga* (\"rod\") and Colombo\'s calling it the sweetness of Venus, Hippocrates used the term *columella* (\"little pillar\"), and Albucasis, an Arabic medical authority, named it *tentigo* (\"tension\"). The names indicated that each description of the structures was about the body and glans of the clitoris but usually the glans. It was additionally known to the Romans, who named it (vulgar slang) *landica*. However, Albertus Magnus, one of the most prolific writers of the Middle Ages, felt that it was important to highlight \"homologies between male and female structures and function\" by adding \"a psychology of sexual arousal\" that Aristotle had not used to detail the clitoris. While in Constantine\'s treatise *Liber de Coitu*, the clitoris is referred to a few times, Magnus gave an equal amount of attention to male and female organs.
Like Avicenna, Magnus also used the word *virga* for the clitoris, but employed it for the male and female genitals; despite his efforts to give equal ground to the clitoris, the cycle of suppression and rediscovery of the organ continued, and a 16th-century justification for clitoridectomy appears to have been confused with intersex conditions and the imprecision created by the word *nymphae* substituted for the word *clitoris*. Nymphotomy was a medical operation to excise an unusually large clitoris, but what was considered \"unusually large\" was often a matter of perception. The procedure was routinely performed on Egyptian women, due to physicians such as Jacques Daléchamps who believed that this version of the clitoris was \"an unusual feature that occurred in almost all Egyptian women \[and\] some of ours, so that when they find themselves in the company of other women, or their clothes rub them while they walk or their husbands wish to approach them, it erects like a male penis and indeed they use it to play with other women, as their husbands would do \... Thus the parts are cut\".
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## Society and culture {#society_and_culture}
### 17th century--present day knowledge and vernacular {#th_centurypresent_day_knowledge_and_vernacular}
thumb\|right\|upright=1\|A Georg Ludwig Kobelt illustration of the anatomy of the clitoris (1844)
Caspar Bartholin (whom Bartholin\'s glands are named after), a 17th-century Danish anatomist, dismissed Colombo\'s and Falloppio\'s claims that they discovered the clitoris, arguing that the clitoris had been widely known to medical science since the second century. Although 17th-century midwives recommended to men and women that women should aspire to achieve orgasms to help them get pregnant for general health and well-being and to keep their relationships healthy, debate about the importance of the clitoris persisted, notably in the work of Regnier de Graaf in the 17th century and Georg Ludwig Kobelt in the 19th.
Like Falloppio and Bartholin, de Graaf criticized Colombo\'s claim of having discovered the clitoris; his work appears to have provided the first comprehensive account of clitoral anatomy. \"We are extremely surprised that some anatomists make no more mention of this part than if it did not exist at all in the universe of nature\", he stated. \"In every cadaver, we have so far dissected we have found it quite perceptible to sight and touch\". De Graaf stressed the need to distinguish `{{em|nympha}}`{=mediawiki} from `{{em|clitoris}}`{=mediawiki}, choosing to \"always give \[the clitoris\] the name clitoris\" to avoid confusion; this resulted in the frequent use of the correct name for the organ among anatomists, but considering that `{{em|nympha}}`{=mediawiki} was also varied in its use and eventually became the term specific to the labia minora, more confusion ensued. Debate about whether orgasm was even necessary for women began in the Victorian era, and Freud\'s 1905 theory about the immaturity of clitoral orgasms (see above) negatively affected women\'s sexuality throughout most of the 20th century.
Toward the end of World War I, a maverick British MP named Noel Pemberton Billing published an article entitled \"The Cult of the Clitoris\", furthering his conspiracy theories and attacking the actress Maud Allan and Margot Asquith, wife of the prime minister. The accusations led to a sensational libel trial, which Billing eventually won; Philip Hoare reports that Billing argued that \"as a medical term, \'clitoris\' would only be known to the \'initiated\', and was incapable of corrupting moral minds\". Jodie Medd argues regarding \"The Cult of the Clitoris\" that \"the female non-reproductive but desiring body \[\...\] simultaneously demands and refuses interpretative attention, inciting scandal through its very resistance to representation\".
From the 18th to the 20th century, especially during the 20th, details of the clitoris from various genital diagrams presented in earlier centuries were omitted from later texts. The full extent of the clitoris was alluded to by Masters and Johnson in 1966, but in such a muddled fashion that the significance of their description became obscured; in 1981, the Federation of Feminist Women\'s Health Clinics (FFWHC) continued this process with anatomically precise illustrations identifying 18 structures of the clitoris. Despite the FFWHC\'s illustrations, Josephine Lowndes Sevely, in 1987, described the vagina as more of the counterpart of the penis.
Concerning other beliefs about the clitoris, Hite (1976 and 1981) found that, during sexual intimacy with a partner, clitoral stimulation was more often described by women as foreplay than as a primary method of sexual activity, including orgasm. Further, although the FFWHC\'s work significantly propelled feminist reformation of anatomical texts, it did not have a general impact. Helen O\'Connell\'s late 1990s research motivated the medical community to start changing the way the clitoris is anatomically defined. O\'Connell describes typical textbook descriptions of the clitoris as lacking detail and including inaccuracies, such as older and modern anatomical descriptions of the female human urethral and genital anatomy having been based on dissections performed on elderly cadavers whose erectile (clitoral) tissue had shrunk. She instead credits the work of Georg Ludwig Kobelt as the most comprehensive and accurate description of clitoral anatomy. MRI measurements, which provide a live and multi-planar method of examination, now complement the FFWHC\'s, as well as O\'Connell\'s, research efforts concerning the clitoris, showing that the volume of clitoral erectile tissue is ten times that which is shown in doctors\' offices and anatomy textbooks.
In Bruce Bagemihl\'s survey of *The Zoological Record* (1978--1997)`{{snds}}`{=mediawiki}which contains over a million documents from over 6,000 scientific journals`{{snds}}`{=mediawiki}539 articles focusing on the penis were found, while seven were found focusing on the clitoris. In 2000, researchers Shirley Ogletree and Harvey Ginsberg concluded that there is a general neglect of the word `{{em|clitoris}}`{=mediawiki} in the common vernacular. They looked at the terms used to describe genitalia in the PsycINFO database from 1887 to 2000 and found that `{{em|penis}}`{=mediawiki} was used in 1,482 sources, `{{em|vagina}}`{=mediawiki} in 409, while `{{em|clitoris}}`{=mediawiki} was only mentioned in 83. They additionally analyzed 57 books listed in a computer database for sex instruction. In the majority of the books, `{{em|penis}}`{=mediawiki} was the most commonly discussed body part`{{snds}}`{=mediawiki}mentioned more than `{{em|clitoris}}`{=mediawiki}, `{{em|vagina}}`{=mediawiki}, and `{{em|uterus}}`{=mediawiki} put together. They last investigated terminology used by college students, ranging from Euro-American (76%/76%), Hispanic (18%/14%), and African American (4%/7%), regarding the students\' beliefs about sexuality and knowledge on the subject. The students were overwhelmingly educated to believe that the vagina is the female counterpart of the penis. The authors found that the student\'s belief that the inner portion of the vagina is the most sexually sensitive part of the female body correlated with negative attitudes toward masturbation and strong support for sexual myths.
thumb\|upright=1\|Protester for clitoris awareness at a women\'s rights rally in Paris, France (2019)
A study in 2005 reported that, among a sample of undergraduate students, the most frequently cited sources for knowledge about the clitoris were school and friends, and that this was associated with the least tested knowledge. Knowledge of the clitoris by self-exploration was the least cited, but \"respondents correctly answered, on average, three of the five clitoral knowledge measures\". The authors stated that \"\[k\]nowledge correlated significantly with the frequency of women\'s orgasm in masturbation but not partnered sex\" and that their \"results are discussed in light of gender inequality and a social construction of sexuality, endorsed by both men and women, that privileges men\'s sexual pleasure over women\'s, such that orgasm for women is pleasing but ultimately incidental\". They concluded that part of the solution to remedying \"this problem\" requires that males and females are taught more about the clitoris than is currently practiced.
The humanitarian group Clitoraid launched the first annual International Clitoris Awareness Week, from 6 to 12 May in 2015. Clitoraid spokesperson Nadine Gary stated that the group\'s mission is to raise public awareness about the clitoris because it has \"been ignored, vilified, made taboo, and considered sinful and shameful for centuries\". (See also Vulva activism)
Odile Fillod created a 3D printable, open source, full-size model of the clitoris, for use in a set of anti-sexist videos she had been commissioned to produce. Fillod was interviewed by Stephanie Theobald, whose article in *The Guardian* stated that the 3D model would be used for sex education in French schools, from primary to secondary level, from September 2016 onwards; this was not the case, but the story went viral across the world.
A questionnaire in a 2019 study was administered to a sample of educational sciences postgraduate students to trace the level of their knowledge concerning the organs of the female and male reproductive system. The authors reported that about two-thirds of the students failed to name parts of the vulva, such as the clitoris and labia, even after detailed pictures were provided to them. An analysis in 2022 reported that the clitoris is mentioned in only one out of 113 Greek secondary education textbooks used in biology classes from the 1870s to present.
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# Clitoris
## Society and culture {#society_and_culture}
### Contemporary art {#contemporary_art}
New York artist Sophia Wallace started work in 2012 on a multimedia project to challenge misconceptions about the clitoris. Based on O\'Connell\'s 1998 research, Wallace\'s work emphasizes the sheer scope and size of the human clitoris. She says that ignorance of this still seems to be pervasive in modern society. \"It is a curious dilemma to observe the paradox that on the one hand, the female body is the primary metaphor for sexuality, its use saturates advertising, art, and the mainstream erotic imaginary\", she said. \"Yet, the clitoris, the true female sexual organ, is virtually invisible\". The project is called `{{em|Cliteracy}}`{=mediawiki} and it includes a \"clit rodeo\", which is interactive, climb-on model of a giant golden clitoris, including its inner parts, produced with the help of sculptor Kenneth Thomas. \"It\'s been a showstopper wherever it\'s been shown. People are hungry to be able to talk about this\", Wallace said. \"I love seeing men standing up for the clit \[\...\] Cliteracy is about not having one\'s body controlled or legislated \[\...\] Not having access to the pleasure that is your birthright is a deeply political act\".
Another project started in New York, in 2016, street art that has since spread to almost 100 cities: Clitorosity, a \"community-driven effort to celebrate the full structure of the clitoris\", combining chalk drawings and words to spark interaction and conversation with passers-by, which the team documents on social media. In 2016, Lori-Malépart Traversy made an animated documentary about the unrecognized anatomy of the clitoris.
Alli Sebastian Wolf created a golden `{{Ratio|100|1}}`{=mediawiki} scale model of the clitoris in 2017, called the *Glitoris* and said, she hopes knowledge of the clitoris will soon become so uncontroversial that making art about them would be as irrelevant as making art about penises.
Other projects listed by the BBC include Clito Clito, body-positive jewellery made in Berlin; *Clitorissima*, a documentary intended to normalize mother-daughter conversations about the clitoris; and a ClitArt festival in London, encompassing spoken word performances as well as visual art. French art collective Les Infemmes (a blend word of \"infamous\" and \"women\") published a fanzine whose title can be translated as \"The Clit Cheatsheet\".
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# Clitoris
## Society and culture {#society_and_culture}
### Influence on female genital mutilation {#influence_on_female_genital_mutilation}
Significant controversy surrounds female genital mutilation (FGM), with the World Health Organization (WHO) being one of many health organizations that have campaigned against the procedures on behalf of human rights, stating that \"FGM has no health benefits\" and that it is \"a violation of the human rights of girls and women\" which \"reflects deep-rooted inequality between the sexes\". The practice has existed at one point or another in almost all human civilizations, most commonly to exert control over the sexual behavior, including masturbation, of girls and women, but also to change the clitoris\' appearance. Custom and tradition are the most frequently cited reasons for FGM, with some cultures believing that not performing it has the possibility of disrupting the cohesiveness of their social and political systems, such as FGM also being a part of a girl\'s initiation into adulthood. Often, a girl is not considered an adult in an FGM-practicing society unless she has undergone FGM, and the \"removal of the clitoris and labia`{{snds}}`{=mediawiki}viewed by some as the `{{em|male parts}}`{=mediawiki} of a woman\'s body`{{snds}}`{=mediawiki}is thought to enhance the girl\'s femininity, often synonymous with docility and obedience\".
Female genital mutilation is carried out in several societies, especially in Africa, with 85 percent of genital mutilations performed in Africa consisting of clitoridectomy or excision, and to a lesser extent in other parts of the Middle East and Southeast Asia, on girls from a few days old to mid-adolescent, often to reduce the sexual desire to preserve vaginal virginity. The practice of FGM has spread globally, as immigrants from Asia, Africa, and the Middle East bring the custom with them. In the United States, it is sometimes practiced on girls born with a clitoris that is larger than usual. Comfort Momoh, who specializes in the topic of FGM, states that FGM might have been \"practiced in ancient Egypt as a sign of distinction among the aristocracy\"; there are reports that traces of infibulation are on Egyptian mummies. FGM is still routinely practiced in Egypt. Greenberg et al. report that \"one study found that 97 percent of married women in Egypt had had some form of genital mutilation performed\". Amnesty International estimated in 1997 that more than two million FGM procedures are performed every year. `{{Anchor|In other animals}}`{=mediawiki}
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# Clitoris
## Other animals {#other_animals}
Although the clitoris (and clitoral prepuce/sheath) exists in all mammal species, there are few detailed studies of the anatomy of the clitoris in non-humans. Studies have been done on the clitoris of cats, sheep and mice. Some mammals have clitoral glands. The clitoris is especially developed in fossas, non-human apes, lemurs, moles, and often contains a small bone known as the os clitoridis. Many species of talpid moles exhibit peniform clitorises that are tunneled by the urethra and are found to have erectile tissue. The clitoris is contained in fossa, which is a small pouch of tissue in horses and dogs. The clitoris is found in other amniotic creatures including reptiles such as turtles and crocodilians, and birds such as ratites (e.g., cassowaries, ostriches) and anatids (e.g., swans, ducks). The hemiclitoris is one-half of a paired structure in squamates (lizards and snakes). Some intersex female bears mate and give birth through the tip of the clitoris; these species are grizzly bears, brown bears, American black bears and polar bears. Although the bears have been described as having \"a birth canal that runs through the clitoris rather than forming a separate vagina\" (a feature that is estimated to make up 10 to 20 percent of the bears\' population), scientists state that female spotted hyenas are the only non-intersex female mammals devoid of an external vaginal opening, and whose sexual anatomy is distinct from usual intersex cases.
### Non-human primates {#non_human_primates}
In spider monkeys, the clitoris is especially developed and has an interior passage, or urethra, that makes it almost identical to the penis, and it retains and distributes urine droplets as the female spider monkey moves around. Scholar Alan F. Dixson stated that this urine \"is voided at the bases of the clitoris, flows down the shallow groove on its perineal surface, and is held by the skin folds on each side of the groove\". Because spider monkeys of South America have pendulous and erectile clitorises long enough to be mistaken for a penis, researchers and observers of the species look for a scrotum to determine the animal\'s sex; a similar approach is to identify scent-marking glands that may also be present on the clitoris.
The clitoris erects in squirrel monkeys during dominance displays, which indirectly influences the squirrel monkeys\' reproductive success.
The clitoris of bonobos is larger and more externalized than in most mammals; Natalie Angier said that a young adolescent \"female bonobo is maybe half the weight of a human teenager, but her clitoris is three times bigger than the human equivalent, and visible enough to waggle unmistakably as she walks\". Female bonobos often engage in the practice of genital-genital (GG) rubbing. Ethologist Jonathan Balcombe stated that female bonobos rub their clitorises together rapidly for ten to twenty seconds, and this behavior, \"which may be repeated in rapid succession, is usually accompanied by grinding, shrieking, and clitoral engorgement\"; he added that, on average, they engage in this practice \"about once every two hours\", and as bonobos sometimes mate face-to-face, \"evolutionary biologist Marlene Zuk has suggested that the position of the clitoris in bonobos and some other primates has evolved to maximize stimulation during sexual intercourse\".
Many strepsirrhine species exhibit elongated clitorises that are either fully or partially tunneled by the urethra, including mouse lemurs, dwarf lemurs, all *Eulemur* species, lorises and galagos. Some of these species also exhibit a membrane seal across the vagina that closes the vaginal opening during the non-mating seasons, most notably mouse and dwarf lemurs. The clitoral morphology of the ring-tailed lemur is the most well-studied. They are described as having \"elongated, pendulous clitorises that are \[fully\] tunneled by a urethra\". The urethra is surrounded by erectile tissue, which allows for significant swelling during breeding seasons, but this erectile tissue differs from the typical male corpus spongiosum. Non-pregnant adult ring-tailed females do not show higher testosterone levels than males, but they do exhibit higher A~4~ and estrogen levels during seasonal aggression. During pregnancy, estrogen, A~4~, and testosterone levels are raised, but female fetuses are still \"protected\" from excess testosterone. These \"masculinized\" genitalia are often found alongside other traits, such as female-dominated social groups, reduced sexual dimorphism that makes females the same size as males, and even ratios of sexes in adult populations. This phenomenon that has been dubbed the \"lemur syndrome\". A 2014 study of *Eulemur* masculinization proposed that behavioral and morphological masculinization in female Lemuriformes is an ancestral trait that likely emerged after their split from Lorisiformes.
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# Clitoris
## Other animals {#other_animals}
### Spotted hyenas {#spotted_hyenas}
While female spotted hyenas were sometimes referred to as pseudohermaphrodites and scientists of ancient and later historical times believed that they were hermaphrodites, modern scientists do not refer to them as such. That designation is typically reserved for those who simultaneously exhibit features of both sexes; the genetic makeup of female spotted hyenas \"are clearly distinct\" from male spotted hyenas.
Female spotted hyenas have a clitoris 90 percent as long and the same diameter as a male penis (171 millimetres long and 22 millimetres in diameter), and this pseudo-penis\' formation seems largely androgen-independent because it appears in the female fetus before differentiation of the fetal ovary and adrenal gland. The spotted hyenas have a highly erectile clitoris, complete with a false scrotum; author John C. Wingfield stated that \"the resemblance to male genitalia is so close that sex can be determined with confidence only by palpation of the scrotum\". The pseudo-penis can also be distinguished from the males\' genitalia by its greater thickness and more rounded glans. The female possesses no external vagina, as the labia are fused to form a pseudo-scrotum. In the females, this scrotum consists of soft adipose tissue. Like male spotted hyenas with regard to their penises, the female spotted hyenas have small spines on the head of their clitorises, which scholar Catherine Blackledge said makes \"the clitoris tip feel like soft sandpaper\". She added that the clitoris \"extends away from the body in a sleek and slender arc, measuring, on average, over 17 cm from root to tip. Just like a penis, \[it\] is fully erectile, raising its head in hyena greeting ceremonies, social displays, games of rough and tumble or when sniffing out peers\".
thumb\|upright=1.8\|**Male and female reproductive systems of the spotted hyena, from Schmotzer & Zimmerman, *Anatomischer Anzeiger* (1922)**. Abb. 1 (Fig. 1.) *Male reproductive anatomy*. Abb. 2 (Fig. 2.) *Female reproductive anatomy*. Principal abbreviations (from Schmotzer & Zimmerman) are: **T**, testis; **VD**, vas deferens; **BU**, bulbus urethrae; **Ur**, urethra; **R**, rectum; **P**, penis; **S**, scrotum; **O**, ovarium; **FT**, tuba Fallopii; **RL**, ligamentum uteri; **Ut**, uterus; **CC**, corpus clitoridis. Remaining abbreviations, in alphabetical order, are: *AG*, glandula analis; *B*, vesica urinaria; *CG*, glandula Cowperi; *CP*, corpus penis; *CS*, corpus spongiosum; *GC*, glans clitoridis; *GP*, glans penis; *LA*, musculus levator ani; *Pr*, praeputium; *RC*, musculus retractor clitoridis; *RP*, musculus retractor penis; *UCG*, canalis urogenitalis. `{{anchor|Genital grooming}}`{=mediawiki} Due to their higher levels of androgen exposure during fetal development, the female hyenas are significantly more muscular and aggressive than their male counterparts; social-wise, they are of higher rank than the males, being dominant or dominant and alpha, and the females who have been exposed to higher levels of androgen than average become higher-ranking than their female peers. Subordinate females lick the clitorises of higher-ranked females as a sign of submission and obedience, but females also lick each other\'s clitorises as a greeting or to strengthen social bonds; in contrast, while all males lick the clitorises of dominant females, the females will not lick the penises of males because males are considered to be of lowest rank.
The female spotted hyenas urinate, copulate and give birth through the clitoris since the urethra and vagina exit through the clitoral glans. This trait makes mating more laborious for the male than in other mammals, and also makes attempts to sexually coerce (physically force sexual activity on) females futile. Joan Roughgarden, an ecologist and evolutionary biologist, said that because the hyena\'s clitoris is higher on the belly than the vagina in most mammals, the male hyena \"must slide his rear under the female when mating so that his penis lines up with \[her clitoris\]\". In an action similar to pushing up a shirtsleeve, the \"female retracts the \[pseudo-penis\] on itself, and creates an opening into which the male inserts his own penis\". The male must practice this act, which can take a couple of months to successfully perform. Female spotted hyenas exposed to larger doses of androgen have significantly damaged ovaries, making it difficult to conceive. After giving birth, the pseudo-penis is stretched and loses much of its original aspects; it becomes a slack-walled and reduced prepuce with an enlarged orifice with split lips. Approximately 15% of the females die during their first time giving birth, and over 60% of their species\' firstborn young die.
A 2006 Baskin et al. study concluded, \"The basic anatomical structures of the corporeal bodies in both sexes of humans and spotted hyenas were similar. As in humans, the dorsal nerve distribution was unique in being devoid of nerves at the 12 o\'clock position in the penis and clitoris of the spotted hyena\" and that \"\[d\]orsal nerves of the penis/clitoris in humans and male spotted hyenas tracked along both sides of the corporeal body to the corpus spongiosum at the 5 and 7 o\'clock positions. The dorsal nerves penetrated the corporeal body and distally the glans in the hyena\", and in female hyenas, \"the dorsal nerves fanned out laterally on the clitoral body. Glans morphology was different in appearance in both sexes, being wide and blunt in the female and tapered in the male\"
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# Outline of chemistry
The following outline acts as an overview of and topical guide to chemistry:
**Chemistry** is the science of atomic matter (matter that is composed of chemical elements), especially its chemical reactions, but also including its properties, structure, composition, behavior, and changes as they relate to the chemical reactions. Chemistry is centrally concerned with atoms and their interactions with other atoms, and particularly with the properties of chemical bonds. `{{TOC limit|limit=2}}`{=mediawiki}
## Summary
Chemistry can be described as all of the following:
- An academic discipline -- one with academic departments, curricula and degrees; national and international societies; and specialized journals.
- A scientific field (a branch of science) -- widely recognized category of specialized expertise within science, and typically embodies its own terminology and nomenclature. Such a field will usually be represented by one or more scientific journals, where peer-reviewed research is published. There are several chemistry-related scientific journals.
- A natural science -- one that seeks to elucidate the rules that govern the natural world using empirical and scientific method.
- A physical science -- one that studies non-living systems.
- A biological science -- one that studies the role of chemicals and chemical processes in living organisms. *See Outline of biochemistry.*
## Branches
- Physical chemistry -- study of the physical and fundamental basis of chemical systems and processes. In particular, the energetics and dynamics of such systems and processes are of interest to physical chemists. Important areas of study include chemical thermodynamics, chemical kinetics, electrochemistry, statistical mechanics, spectroscopy, and more recently, astrochemistry. Physical chemistry has large overlap with molecular physics. Physical chemistry involves the use of infinitesimal calculus in deriving equations. It is usually associated with quantum chemistry and theoretical chemistry. Physical chemistry is a distinct discipline from chemical physics, but again, there is very strong overlap.
- Chemical kinetics -- study of rates of chemical processes.
- Chemical physics -- investigates physicochemical phenomena using techniques from atomic and molecular physics and condensed matter physics; it is the branch of physics that studies chemical processes.
- Electrochemistry -- branch of chemistry that studies chemical reactions which take place in a solution at the interface of an electron conductor (the electrode: a metal or a semiconductor) and an ionic conductor (the electrolyte), and which involve electron transfer between the electrode and the electrolyte or species in solution.
- Femtochemistry -- area of physical chemistry that studies chemical reactions on extremely short timescales, approximately 10^−15^ seconds (one femtosecond).
- Geochemistry -- chemical study of the mechanisms behind major systems studied in geology.
- Photochemistry -- study of chemical reactions that proceed with the absorption of light by atoms or molecules.
- Quantum chemistry -- branch of chemistry whose primary focus is the application of quantum mechanics in physical models and experiments of chemical systems.
- Solid-state chemistry -- study of the synthesis, structure, and properties of solid phase materials, particularly, but not necessarily exclusively of, non-molecular solids.
- Spectroscopy -- study of the interaction between matter and radiated energy.
- Stereochemistry -- study of the relative spatial arrangement of atoms that form the structure of molecules
- Surface science -- study of physical and chemical phenomena that occur at the interface of two phases, including solid--liquid interfaces, solid--gas interfaces, solid--vacuum interfaces, and liquid-gas interfaces.
- Thermochemistry -- the branch of chemistry that studies the relation between chemical action and the amount of heat absorbed or generated.
- Calorimetry -- the study of heat changes in physical and chemical processes.
- Organic chemistry (outline) -- study of the structure, properties, composition, mechanisms, and reactions of organic compounds. An organic compound is defined as any compound based on a carbon skeleton.
- Biochemistry -- study of the chemicals, chemical reactions and chemical interactions that take place in living organisms. Biochemistry and organic chemistry are closely related, as in medicinal chemistry or neurochemistry. Biochemistry is also associated with molecular biology and genetics.
- Neurochemistry -- study of neurochemicals; including transmitters, peptides, proteins, lipids, sugars, and nucleic acids; their interactions, and the roles they play in forming, maintaining, and modifying the nervous system.
- Molecular biochemistry and genetic engineering -- an area of biochemistry and molecular biology that studies the genes, their heritage and their expression.
- Bioorganic chemistry -- combines organic chemistry and biochemistry toward biology.
- Biophysical chemistry -- is a physical science that uses the concepts of physics and physical chemistry for the study of biological systems.
- Medicinal chemistry -- discipline which applies chemistry for medical or drug related purposes.
- Organometallic chemistry -- is the study of organometallic compounds, chemical compounds containing at least one chemical bond between a carbon atom of an organic molecule and a metal, including alkaline, alkaline earth, and transition metals, and sometimes broadened to include metalloids like boron, silicon, and tin.
- Physical organic chemistry -- study of the interrelationships between structure and reactivity in organic molecules.
- Inorganic chemistry -- study of the properties and reactions of inorganic compounds. The distinction between organic and inorganic disciplines is not absolute and there is much overlap, most importantly in the sub-discipline of organometallic chemistry.
- Bioinorganic chemistry -- is a field that examines the role of metals in biology.
- Cluster chemistry -- focuses on crystalline materials most often existing on the 0--2 nanometer scale and characterizing their crystal structures and understanding their role in the nucleation and growth mechanisms of larger materials.
- Nuclear chemistry -- study of how subatomic particles come together and make nuclei. Modern transmutation is a large component of nuclear chemistry, and the table of nuclides is an important result and tool for this field.
- Analytical chemistry -- analysis of material samples to gain an understanding of their chemical composition and structure. Analytical chemistry incorporates standardized experimental methods in chemistry. These methods may be used in all subdisciplines of chemistry, excluding purely theoretical chemistry.
**Other**
- Astrochemistry -- study of the abundance and reactions of chemical elements and molecules in the universe, and their interaction with radiation.
- Cosmochemistry -- study of the chemical composition of matter in the universe and the processes that led to those compositions.
- Computational chemistry -- is a branch of chemistry that uses computer simulations for solving chemical problems.
- Environmental chemistry -- study of chemical and biochemical phenomena that occur diverse aspects of the environment such the air, soil, and water. It also studies the effects of human activity on the environment.
- Green chemistry is a philosophy of chemical research and engineering that encourages the design of products and processes that minimize the use and generation of hazardous substances.
- Supramolecular chemistry -- refers to the domain of chemistry beyond that of molecules and focuses on the chemical systems made up of a discrete number of assembled molecular subunits or components.
- Theoretical chemistry -- study of chemistry via fundamental theoretical reasoning (usually within mathematics or physics). In particular the application of quantum mechanics to chemistry is called quantum chemistry. Since the end of the Second World War, the development of computers has allowed a systematic development of computational chemistry, which is the art of developing and applying computer programs for solving chemical problems. Theoretical chemistry has large overlap with (theoretical and experimental) condensed matter physics and molecular physics.
- Polymer chemistry -- multidisciplinary science that deals with the chemical synthesis and chemical properties of polymers or macromolecules.
- Wet chemistry -- is a form of analytical chemistry that uses classical methods such as observation to analyze materials usually in liquid phase.
- Agrochemistry -- study and application of both chemistry and biochemistry for agricultural production, the processing of raw products into foods and beverages, and environmental monitoring and remediation.
- Atmospheric chemistry -- branch of atmospheric science which studies the chemistry of the Earth\'s atmosphere and that of other planets.
- Chemical biology -- scientific discipline spanning the fields of chemistry and biology and involves the application of chemical techniques and tools, often compounds produced through synthetic chemistry, to analyze and manipulation of biological systems.
- Chemo-informatics -- use of computer and informational techniques applied to a range of problems in the field of chemistry.
- Flow chemistry -- study of chemical reactions in continuous flow, not as stationary batches, in industry and macro processing equipment.
- Immunohistochemistry -- involves the process of detecting antigens (e.g., proteins) in cells of a tissue section by exploiting the principle of antibodies binding specifically to antigens in biological tissues.
- Immunochemistry -- is a branch of chemistry that involves the study of the reactions and components on the immune system.
- Chemical oceanography -- study of ocean chemistry: the behavior of the chemical elements within the Earth\'s oceans.
- Mathematical chemistry -- area of study engaged in novel applications of mathematics to chemistry. It concerns itself principally with the mathematical modeling of chemical phenomena.
- Mechanochemistry -- coupling of mechanical and chemical phenomena on a molecular scale.
- Molecular biology -- study of interactions between the various systems of a cell. It overlaps with biochemistry.
- Petrochemistry -- study of the transformation of petroleum and natural gas into useful products or raw materials.
- Phytochemistry -- study of phytochemicals which come from plants.
- Radiochemistry -- chemistry of radioactive materials.
- Sonochemistry -- study of effect of sonic waves and wave properties on chemical systems.
- Synthetic chemistry -- study of chemical synthesis.
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# Outline of chemistry
## History
History of chemistry
- Precursors to chemistry
- Alchemy (outline)
- History of alchemy
- History of the branches of chemistry
- History of analytical chemistry -- history of the study of separation, identification, and quantification of the chemical components of natural and artificial materials.
- History of astrochemistry -- history of the study of the abundance and reactions of chemical elements and molecules in the universe, and their interaction with radiation.
- History of cosmochemistry -- history of the study of the chemical composition of matter in the universe and the processes that led to those compositions
- History of atmospheric chemistry -- history of the branch of atmospheric science in which the chemistry of the Earth\'s atmosphere and that of other planets is studied. It is a multidisciplinary field of research and draws on environmental chemistry, physics, meteorology, computer modeling, oceanography, geology and volcanology and other disciplines
- History of biochemistry -- history of the study of chemical processes in living organisms, including, but not limited to, living matter. Biochemistry governs all living organisms and living processes.
- History of agrochemistry -- history of the study of both chemistry and biochemistry which are important in agricultural production, the processing of raw products into foods and beverages, and in environmental monitoring and remediation.
- History of bioinorganic chemistry -- history of the examination of the role of metals in biology.
- History of bioorganic chemistry -- history of the rapidly growing scientific discipline that combines organic chemistry and biochemistry.
- History of biophysical chemistry -- history of the new branch of chemistry that covers a broad spectrum of research activities involving biological systems.
- History of environmental chemistry -- history of the scientific study of the chemical and biochemical phenomena that occur in natural places.
- History of immunochemistry -- history of the branch of chemistry that involves the study of the reactions and components of the immune system.
- History of medicinal chemistry -- history of the discipline at the intersection of chemistry, especially synthetic organic chemistry, and pharmacology and various other biological specialties, where they are involved with design, chemical synthesis and development for market of pharmaceutical agents (drugs).
- History of natural product chemistry -- history of the scientific study of chemical compounds or substances produced by living organisms---history of chemical compounds found in nature that usually have a pharmacological or biological activity for use in pharmaceutical drug discovery and drug design.
- History of neurochemistry -- history of the specific study of neurochemicals, which include neurotransmitters and other molecules such as neuro-active drugs that influence neuron function.
- History of computational chemistry -- history of the branch of chemistry that uses principles of computer science to assist in solving chemical problems.
- History of chemo-informatics -- history of the use of computer and informational techniques, applied to a range of problems in the field of chemistry.
- History of molecular mechanics -- history of the uses of Newtonian mechanics to model molecular systems.
- History of flavor chemistry -- history of the use of chemistry to engineer artificial and natural flavors.
- History of flow chemistry -- history of chemical reactions run in a continuously flowing stream rather than in batch production.
- History of geochemistry -- history of the study of the mechanisms behind major geological systems using chemistry
- History of aqueous geochemistry -- history of the study of the role of various elements in watersheds, including copper, sulfur, mercury, and how elemental fluxes are exchanged through atmospheric-terrestrial-aquatic interactions
- History of isotope geochemistry -- history of the study of the relative and absolute concentrations of the elements and their isotopes using chemistry and geology
- History of ocean chemistry -- history of the study the chemistry of marine environments, including the influences of different variables.
- History of organic geochemistry -- history of the study of the impacts and processes that organisms have had on Earth
- History of regional, environmental and exploration geochemistry -- history of the study of the spatial variation in the chemical composition of materials at the surface of the Earth
- History of inorganic chemistry -- history of the branch of chemistry concerned with the properties and behavior of inorganic compounds.
- History of nuclear chemistry -- history of the subfield of chemistry dealing with radioactivity, nuclear processes and nuclear properties.
- History of radiochemistry -- history of the chemistry of radioactive materials, where radioactive isotopes of elements are used to study the properties and chemical reactions of non-radioactive isotopes (often within radiochemistry the absence of radioactivity leads to a substance being described as being inactive as the isotopes are stable).
- History of organic chemistry -- history of the study of the structure, properties, composition, reactions, and preparation (by synthesis or by other means) of carbon-based compounds, hydrocarbons, and their derivatives.
- History of petrochemistry -- history of the branch of chemistry that studies the transformation of crude oil (petroleum) and natural gas into useful products or raw materials.
- History of organometallic chemistry -- history of the study of chemical compounds containing bonds between carbon and a metal.
- History of photochemistry -- history of the study of chemical reactions that proceed with the absorption of light by atoms or molecules.
- History of physical chemistry -- history of the study of macroscopic, atomic, subatomic, and particulate phenomena in chemical systems in terms of physical laws and concepts.
- History of chemical kinetics -- history of the study of rates of chemical processes.
- History of chemical thermodynamics -- history of the study of the interrelation of heat and work with chemical reactions or with physical changes of state within the confines of the laws of thermodynamics.
- History of electrochemistry -- history of the branch of chemistry that studies chemical reactions which take place in a solution at the interface of an electron conductor (a metal or a semiconductor) and an ionic conductor (the electrolyte), and which involve electron transfer between the electrode and the electrolyte or species in solution.
- History of femtochemistry -- history of the science that studies chemical reactions on extremely short timescales, approximately 10^−15^ seconds (one femtosecond, hence the name).
- History of mathematical chemistry -- history of the area of research engaged in novel applications of mathematics to chemistry; it concerns itself principally with the mathematical modeling of chemical phenomena.
- History of mechanochemistry -- history of the coupling of the mechanical and the chemical phenomena on a molecular scale and includes mechanical breakage, chemical behaviour of mechanically stressed solids (e.g., stress-corrosion cracking), tribology, polymer degradation under shear, cavitation-related phenomena (e.g., sonochemistry and sonoluminescence), shock wave chemistry and physics, and even the burgeoning field of molecular machines.
- History of physical organic chemistry -- history of the study of the interrelationships between structure and reactivity in organic molecules.
- History of quantum chemistry -- history of the branch of chemistry whose primary focus is the application of quantum mechanics in physical models and experiments of chemical systems.
- History of sonochemistry -- history of the study of the effect of sonic waves and wave properties on chemical systems.
- History of stereochemistry -- history of the study of the relative spatial arrangement of atoms within molecules.
- History of supramolecular chemistry -- history of the area of chemistry beyond the molecules and focuses on the chemical systems made up of a discrete number of assembled molecular subunits or components.
- History of thermochemistry -- history of the study of energy and heat associated with chemical reactions and/or physical transformations.
- History of phytochemistry -- history of the study of phytochemicals.
- History of polymer chemistry -- history of the multidisciplinary science that deals with the chemical synthesis and chemical properties of polymers or macromolecules.
- History of solid-state chemistry -- history of the study of the synthesis, structure, and properties of solid phase materials, particularly, but not necessarily exclusively of, non-molecular solids
- History of multidisciplinary fields involving chemistry:
- History of chemical biology -- history of the scientific discipline spanning the fields of chemistry and biology that involves the application of chemical techniques and tools, often compounds produced through synthetic chemistry, to the study and manipulation of biological systems.
- History of chemical oceanography -- history of the study of the behavior of chemical elements within the Earth\'s oceans.
- History of chemical physics -- history of the branch of physics that studies chemical processes from the point of view of physics and engineering.
- History of oenology -- history of the science and study of all aspects of wine and winemaking except vine-growing and grape-harvesting, which is a subfield called viticulture.
- History of spectroscopy -- history of the study of the interaction between matter and radiated energy
- History of surface science -- history of the study of physical and chemical phenomena that occur at the interface of two phases, including solid--liquid interfaces, solid--gas interfaces, solid--vacuum interfaces, and liquid--gas interfaces.
- History of chemicals
- History of chemical elements
- History of carbon
- History of hydrogen
- Timeline of hydrogen technologies
- History of oxygen
- History of chemical products
- History of aspirin
- History of cosmetics
- History of gunpowder
- History of pharmaceutical drugs
- History of vitamins
- History of chemical processes
- History of manufactured gas
- History of the Haber process
- History of the chemical industry
- History of the petroleum industry
- History of the pharmaceutical industry
- History of the periodic table
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# Outline of chemistry
## Chemicals
- Dictionary of chemical formulas
- List of biomolecules
- List of inorganic compounds
- Periodic table
## Atomic theory {#atomic_theory}
Atomic theory
- Atomic models
- Atomism -- natural philosophy that theorizes that the world is composed of indivisible pieces.
- Plum pudding model
- Rutherford model
- Bohr model
## Thermochemistry
Thermochemistry
### Terminology
- Thermochemistry
- Chemical kinetics -- the study of the rates of chemical reactions and investigates how different experimental conditions can influence the speed of a chemical reaction and yield information about the reaction\'s mechanism and transition states, as well as the construction of mathematical models that can describe the characteristics of a chemical reaction.
- Exothermic -- a process or reaction in which the system releases energy to its surroundings in the form of heat. They are denoted by negative heat flow.
- Endothermic -- a process or reaction in which the system absorbs energy from its surroundings in the form of heat. They are denoted by positive heat flow.
- Thermochemical equation
- Enthalpy change -- internal energy of a system plus the product of pressure and volume. Its change in a system is equal to the heat brought to the system at constant pressure.
- Enthalpy of reaction
- Temperature -- an objective comparative measure of heat.
- Calorimeter -- an object used for calorimetry, or the process of measuring the heat of chemical reactions or physical changes as well as heat capacity.
- Heat -- A form of energy associated with the kinetic energy of atoms or molecules and capable of being transmitted through solid and fluid media by conduction, through fluid media by convection, and through empty space by radiation.
- Joule -- a unit of energy.
- Calorie
- Specific heat
- Specific heat capacity
- Latent heat
- Heat of fusion
- Heat of vaporization
- Collision theory
- Activation energy
- Activated complex
- Reaction rate
- Catalyst
### Thermochemical equations {#thermochemical_equations}
- Chemical equations that include the **heat** involved in a reaction, either on the reactant side or the product side
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# Outline of critical theory
The following outline is provided as an overview of and topical guide to critical theory:
**Critical theory** -- the examination and critique of society and culture, drawing from knowledge across the social sciences and humanities. The term has two different meanings with different origins and histories: one originating in sociology and the other in literary criticism. This has led to the very literal use of \'critical theory\' as an umbrella term to describe any theory founded upon critique. The term \"Critical Theory\" was first coined by Max Horkheimer in his 1937 essay \"Traditional and Critical Theory\".
## Essence of critical theory {#essence_of_critical_theory}
- Cultural studies --
- Critical theorists --
- Works in critical theory --
- Truth theory --
### Concepts
- Aesthetics
- Agency (sociology)
- Authorship
- History
- Human rights
- Ideology
- Law
- Money
- Objectivity and subjectivity
- Sex--gender distinction
## Branches of critical theory {#branches_of_critical_theory}
- Social theory --
- Literary theory --
- Thing theory --
- Critical theory of technology --
- Critical legal studies --
- Hermeneutics --
## Actor--network theory {#actornetwork_theory}
### Commonly used terms {#commonly_used_terms}
- Articulation (sociology)
- Assemblage (philosophy)
- Blackboxing
## African-American studies {#african_american_studies}
- Henry Louis Gates Jr. --
- Frantz Fanon --
## Gender studies {#gender_studies}
- Lauren Berlant --
- Judith Butler --
- Raewyn Connell --
- Susan McClary --
- Laura Mulvey --
## Marxist theory {#marxist_theory}
### Commonly used terms {#commonly_used_terms_1}
## Postcolonialism
- Chinua Achebe --
- \"An Image of Africa\" --
- Frantz Fanon --
- \"The Wretched of the Earth\" --
- Homi Bhabha --
- Double consciousness --
## Structuralism
- Roland Barthes --
- Ferdinand de Saussure --
- Claude Lévi-Strauss --
- Louis Althusser --
## Post-structuralism {#post_structuralism}
- Roland Barthes --
- Michel Foucault --
- Julia Kristeva --
- Bruno Latour --
### Commonly used terms {#commonly_used_terms_2}
- Critical apparatus
- Event (philosophy)
- Genealogy (philosophy)
- Heterotopia (space)
## Deconstruction
### Commonly used terms {#commonly_used_terms_3}
- Bricolage
## Postmodern philosophy {#postmodern_philosophy}
- Jean-François Lyotard --
- Gilles Deleuze --
- Félix Guattari --
- Ernesto Laclau --
- Claude Lefort --
- A Cyborg Manifesto --
## Reconstructivism
- Paulo Freire --
- John Dewey --
## Psychoanalytic theory {#psychoanalytic_theory}
### Commonly used terms {#commonly_used_terms_4}
## Schizoanalytic theory {#schizoanalytic_theory}
- Félix Guattari --
- Gilles Deleuze --
- Deleuze and Guattari --
### Commonly used terms {#commonly_used_terms_5}
- Assemblage (philosophy)
- Body without organs
- Rhizome (philosophy)
## Queer theory {#queer_theory}
- Judith Butler --
- Heteronormativity --
- Eve Kosofsky Sedgwick --
- Gloria E. Anzaldúa --
- New Queer Cinema --
- Queer pedagogy --
## Semiotics
- Roland Barthes --
- Julia Kristeva --
- Charles Sanders Peirce --
- Ferdinand de Saussure --
### Commonly used terms {#commonly_used_terms_6}
- Semiotic square
## Literary theory {#literary_theory}
- Mikhail Bakhtin
- Mary Louise Pratt --
- René Girard --
### Commonly used terms {#commonly_used_terms_7}
- Carnivalesque
- Chronotope
- Dialogic
- Narratology
- Heteroglossia
## Theories of identity {#theories_of_identity}
- Private sphere -- certain sector of societal life in which an individual enjoys a degree of authority, unhampered by interventions from governmental or other institutions. Examples of the private sphere are family and home. The complement or opposite of public sphere.
- Public sphere -- area in social life where individuals can come together to freely discuss and identify societal problems, and through that discussion influence political action. It is \"a discursive space in which individuals and groups congregate to discuss matters of mutual interest and, where possible, to reach a common judgment.\"
- Creolization
## Major works {#major_works}
- Bloch, Ernst (1938--47). *The Principle of Hope*
- Fromm, Erich (1941). *The Fear of Freedom* (UK)/*Escape from Freedom* (US)
- Horkheimer, Max; Adorno, Theodor W. (1944--47). *Dialectic of Enlightenment*
- Barthes, Roland (1957). *Mythologies*
- Habermas, Jürgen (1962). *The Structural Transformation of the Public Sphere*
- Marcuse, Herbert (1964). *One-Dimensional Man*
- Adorno, Theodor W. (1966). *Negative Dialectics*
- Derrida, Jacques (1967). *Of Grammatology*
- Derrida, Jacques (1967). *Writing and Difference*
- Habermas, Jürgen (1981)
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# Context switch
In computing, a **context switch** is the process of storing the state of a process or thread, so that it can be restored and resume execution at a later point, and then restoring a different, previously saved, state. This allows multiple processes to share a single central processing unit (CPU), and is an essential feature of a multiprogramming or multitasking operating system. In a traditional CPU, each process -- a program in execution -- uses the various CPU registers to store data and hold the current state of the running process. However, in a multitasking operating system, the operating system switches between processes or threads to allow the execution of multiple processes simultaneously. For every switch, the operating system must save the state of the currently running process, followed by loading the next process state, which will run on the CPU. This sequence of operations that stores the state of the running process and loads the following running process is called a context switch.
The precise meaning of the phrase \"context switch\" varies. In a multitasking context, it refers to the process of storing the system state for one task, so that task can be paused and another task resumed. A context switch can also occur as the result of an interrupt, such as when a task needs to access disk storage, freeing up CPU time for other tasks. Some operating systems also require a context switch to move between user mode and kernel mode tasks. The process of context switching can have a negative impact on system performance.
## Cost
Context switches are usually computationally intensive, and much of the design of operating systems is to optimize the use of context switches. Switching from one process to another requires a certain amount of time for doing the administration`{{snd}}`{=mediawiki} saving and loading registers and memory maps, updating various tables and lists, etc. What is actually involved in a context switch depends on the architectures, operating systems, and the number of resources shared (threads that belong to the same process share many resources compared to unrelated non-cooperating processes).
For example, in the Linux kernel, context switching involves loading the corresponding process control block (PCB) stored in the PCB table in the kernel stack to retrieve information about the state of the new process. CPU state information including the registers, stack pointer, and program counter as well as memory management information like segmentation tables and page tables (unless the old process shares the memory with the new) are loaded from the PCB for the new process. To avoid incorrect address translation in the case of the previous and current processes using different memory, the translation lookaside buffer (TLB) must be flushed. This negatively affects performance because every memory reference to the TLB will be a miss because it is empty after most context switches.
Furthermore, analogous context switching happens between user threads, notably green threads, and is often very lightweight, saving and restoring minimal context. In extreme cases, such as switching between goroutines in Go, a context switch is equivalent to a coroutine yield, which is only marginally more expensive than a subroutine call.
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# Context switch
## `{{Anchor|When to switch}}`{=mediawiki}Switching cases {#switching_cases}
There are three potential triggers for a context switch:
### Multitasking
Most commonly, within some scheduling scheme, one process must be switched out of the CPU so another process can run. This context switch can be triggered by the process making itself unrunnable, such as by waiting for an I/O or synchronization operation to complete. On a pre-emptive multitasking system, the scheduler may also switch out processes that are still runnable. To prevent other processes from being starved of CPU time, pre-emptive schedulers often configure a timer interrupt to fire when a process exceeds its time slice. This interrupt ensures that the scheduler will gain control to perform a context switch.
### Interrupt handling {#interrupt_handling}
Modern architectures are interrupt driven. This means that if the CPU requests data from a disk, for example, it does not need to busy-wait until the read is over; it can issue the request (to the I/O device) and continue with some other task. When the read is over, the CPU can be *interrupted* (by a hardware in this case, which sends interrupt request to PIC) and presented with the read. For interrupts, a program called an *interrupt handler* is installed, and it is the interrupt handler that handles the interrupt from the disk.
When an interrupt occurs, the hardware automatically switches a part of the context (at least enough to allow the handler to return to the interrupted code). The handler may save additional context, depending on details of the particular hardware and software designs. Often only a minimal part of the context is changed in order to minimize the amount of time spent handling the interrupt. The kernel does not spawn or schedule a special process to handle interrupts, but instead the handler executes in the (often partial) context established at the beginning of interrupt handling. Once interrupt servicing is complete, the context in effect before the interrupt occurred is restored so that the interrupted process can resume execution in its proper state.
### User and kernel mode switching {#user_and_kernel_mode_switching}
When the system transitions between user mode and kernel mode, a context switch is not necessary; a *mode transition* is not by itself a context switch. However, depending on the operating system, a context switch may also take place at this time.
## Steps
The state of the currently executing process must be saved so it can be restored when rescheduled for execution.
The process state includes all the registers that the process may be using, especially the program counter, plus any other operating system specific data that may be necessary. This is usually stored in a data structure called a *process control block* (PCB) or *switchframe*.
The PCB might be stored on a per-process stack in kernel memory (as opposed to the user-mode call stack), or there may be some specific operating system-defined data structure for this information. A handle to the PCB is added to a queue of processes that are ready to run, often called the *ready queue*.
Since the operating system has effectively suspended the execution of one process, it can then switch context by choosing a process from the ready queue and restoring its PCB. In doing so, the program counter from the PCB is loaded, and thus execution can continue in the chosen process. Process and thread priority can influence which process is chosen from the ready queue (i.e., it may be a priority queue).
## Examples
The details vary depending on the architecture and operating system, but these are common scenarios.
### No context switch needed {#no_context_switch_needed}
Considering a general arithmetic addition operation A = B+1. The instruction is stored in the instruction register and the program counter is incremented. A and B are read from memory and are stored in registers R1, R2 respectively. In this case, B+1 is calculated and written in R1 as the final answer. This operation as there are sequential reads and writes and there\'s no waits for function calls used, hence no context switch/wait takes place in this case.
### Context switch caused by interrupt {#context_switch_caused_by_interrupt}
Suppose a process A is running and a timer interrupt occurs. The user registers --- program counter, stack pointer, and status register --- of process A are then implicitly saved by the CPU onto the kernel stack of A. Then, the hardware switches to kernel mode and jumps into interrupt handler for the operating system to take over. Then the operating system calls the `switch()` routine to first save the general-purpose user registers of A onto A\'s kernel stack, then it saves A\'s current kernel register values into the PCB of A, restores kernel registers from the PCB of process B, and switches context, that is, changes kernel stack pointer to point to the kernel stack of process B. The operating system then returns from interrupt. The hardware then loads user registers from B\'s kernel stack, switches to user mode, and starts running process B from B\'s program counter.
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# Context switch
## `{{Anchor|LATENCY}}`{=mediawiki}Performance
Context switching itself has a cost in performance, due to running the task scheduler, TLB flushes, and indirectly due to sharing the CPU cache between multiple tasks. Switching between threads of a single process can be faster than between two separate processes because threads share the same virtual memory maps, so a TLB flush is not necessary.
The time to switch between two separate processes is called the **process switching latency**. The time to switch between two threads of the same process is called the **thread switching latency**. The time from when a hardware interrupt is generated to when the interrupt is serviced is called the interrupt latency.
Switching between two processes in a single address space operating system can be faster than switching between two processes in an operating system with private per-process address spaces.
### Hardware vs. software {#hardware_vs._software}
Context switching can be performed primarily by software or hardware. Some processors, like the Intel 80386 and its successors, have hardware support for context switches, by making use of a special data segment designated the task state segment (TSS). A task switch can be explicitly triggered with a CALL or JMP instruction targeted at a TSS descriptor in the global descriptor table. It can occur implicitly when an interrupt or exception is triggered if there is a task gate in the interrupt descriptor table (IDT). When a task switch occurs, the CPU can automatically load the new state from the TSS.
As with other tasks performed in hardware, one would expect this to be rather fast; however, mainstream operating systems, including Windows and Linux, do not use this feature. This is mainly due to two reasons:
- Hardware context switching does not save all the registers (only general-purpose registers, not floating-point registers --- although the `TS` bit is automatically turned on in the `CR0` control register, resulting in a fault when executing floating-point instructions and giving the OS the opportunity to save and restore the floating-point state as needed).
- Associated performance issues, e.g., software context switching can be selective and store only those registers that need storing, whereas hardware context switching stores nearly all registers whether they are required or not
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# Rod (optical phenomenon)
In cryptozoology and ufology, \"**rods**\" (also known as \"**skyfish**\", \"**air rods**\", or \"**solar entities**\") are elongated visual artifacts appearing in photographic images and video recordings.
Most optical analyses to date have concluded that the images are insects moving across the frame as the photo is being captured, although cryptozoologists and ufologists claim that they are paranormal in nature.
## Optical analysis {#optical_analysis}
Robert Todd Carroll (2003), having consulted an entomologist (Doug Yanega), identified rods as images of flying insects recorded over several cycles of wing-beating on video recording devices. The insect captured on image a number of times, while propelling itself forward, gives the illusion of a single elongated rod-like body, with bulges.
A 2000 report by staff at \"The Straight Dope\" also explained rods as such phenomena, namely tricks of light which result from how (primarily video) images of flying insects are recorded and played back, adding that investigators have shown the rod-like bodies to be a result of motion blur, if the camera is shooting with relatively long exposure times.
The claims of these being extraordinary creatures, possibly alien, have been advanced by either people with active imaginations, or hoaxers.
In August 2005, China Central Television (CCTV) aired a two-part documentary about flying rods in China. It reported the events from May to June of the same year at Tonghua Zhenguo Pharmaceutical Company in Tonghua City, Jilin Province, which debunked the flying rods. Surveillance cameras in the facility\'s compound captured video footage of flying rods identical to those shown in Jose Escamilla\'s video. Getting no satisfactory answer to the phenomenon, curious scientists at the facility decided that they would try to solve the mystery by attempting to catch these airborne creatures. Huge nets were set up and the same surveillance cameras then captured images of rods flying into the trap. When the nets were inspected, the \"rods\" were no more than regular moths and other ordinary flying insects. Subsequent investigations proved that the appearance of flying rods on video was an optical illusion created by the slower recording speed of the camera.
After attending a lecture by Jose Escamilla, UFO investigator Robert Sheaffer wrote that \"some of his \'rods\' were obviously insects zipping across the field at a high angular rate\" and others appeared to be \"appendages\" which were birds\' wings blurred by the camera exposure.
## Paranormal claims {#paranormal_claims}
Various paranormal interpretations of this phenomenon appear in popular culture. One of the more outspoken proponents of rods as alien life forms was Jose Escamilla, who claimed to have been the first to film them on March 19, 1994, in Roswell, New Mexico, while attempting to film a UFO. Escamilla later made additional videos and embarked on lecture tours to promote his claims
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# Clitoridectomy
**Clitoridectomy** or **clitorectomy** is the surgical removal, reduction, or partial removal of the clitoris. It is rarely used as a therapeutic medical procedure, such as when cancer has developed in or spread to the clitoris. Commonly, non-medical removal of the clitoris is performed during female genital mutilation.
## Medical uses {#medical_uses}
### Malignancies
A clitoridectomy is often done to remove malignancy or necrosis of the clitoris. This is sometimes done along with a radical complete vulvectomy. Surgery may also become necessary due to therapeutic radiation treatments to the pelvic area.
Removal of the clitoris may be due to malignancy or trauma.
### Clitoromegaly and other conditions {#clitoromegaly_and_other_conditions}
Female infants born with a 46,XX genotype but have a clitoris size affected by congenital adrenal hyperplasia and are treated surgically with vaginoplasty that often reduces the size of the clitoris without its total removal. The atypical size of the clitoris is due to an endocrine imbalance in utero. Other reasons for the surgery include issues involving microphallism and those who have Müllerian agenesis. Treatments on children raise human rights concerns.
## Technique
Clitoridectomy surgical techniques are used to remove an invasive malignancy that extends to the clitoris. Standard surgical procedures are followed in these cases. This includes evaluation and biopsy. Other factors that will affect the technique selected are age, other existing medical conditions, and obesity. Other considerations are the probability of extended hospital care and the development of infection at the surgical site.
The surgery proceeds with the use of general anesthesia, and prior to the vulvectomy/clitoridectomy an inguinal lymphadenectomy is first done. The extent of the surgical site extends 1 to 2 cm beyond the boundaries of malignancy. Superficial lymph nodes may also need to be removed. If the malignancy is present in any muscles in the region, then the affected muscle tissue is also removed. In some cases, the surgeon is able to preserve the clitoris despite extensive malignancy. The cancerous tissue is removed and the incision is closed.
Post-operative care may employ the use of suction drainage to allow the deeper tissues to heal toward the surface. Follow-up after surgery includes the stripping of the drainage device to prevent blockage. A typical hospital stay can last up to two weeks. The site of the surgery is left unbandaged to allow for frequent examination.
Complications can include the development of lymphedema; not removing the saphenous vein during the surgery can help prevent this. In some instances, the buildup of fluid can be reduced through methods such as foot elevation, diuretic medication, and wearing compression stockings.
In a clitoridectomy for infants with a clitoromegaly, the clitoris is often reduced instead of removed. The surgeon cuts the shaft of the elongated phallus and sews the glans and preserved nerves back onto the stump. In a less common surgery called clitoral recession, the surgeon hides the clitoral shaft under a fold of skin so only the glans remains visible.
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# Clitoridectomy
## Society and culture {#society_and_culture}
### General
While much feminist scholarship has described clitoridectomy as a practice aimed at controlling women\'s sexuality, the historic emergence of the practice in ancient European and Middle Eastern cultures may also have derived from ideas about what a normal female genitalia should look like and the policing of boundaries between the sexes.
In the seventeenth century, anatomists remained divided on whether a clitoris was a normal female organ, with some arguing that it was an abnormality in female development and, if large enough to be visible, it should always be removed at birth. In the 19th century, a clitoridectomy was thought by some to curb female masturbation; until the late 19th century, masturbation was thought by many to be unhealthy or immoral. Isaac Baker Brown (1812--1873), an English gynaecologist who was president of the Medical Society of London believed that the \"unnatural irritation\" of the clitoris caused epilepsy, hysteria, and mania, and he worked \"to remove \[it\] whenever he had the opportunity of doing so\", according to his obituary in the *Medical Times and Gazette*. Peter Lewis Allen writes that Brown\'s views caused outrage, and he died penniless after being expelled from the Obstetrical Society.Allen, Peter Lewis. *The Wages of Sin: Sex and Disease, Past and Present*. University of Chicago Press, 2000, [p. 106](https://archive.org/details/wagesofsinsexdis00alle/page/106).
- For the obituary, see J.F.C. [\"Isaac Baker Brown, F.R.C.S.\"](https://books.google.com/books?id=gZ4EAAAAQAAJ&pg=PA155) `{{Webarchive|url=https://web.archive.org/web/20231223171914/https://books.google.com/books?id=gZ4EAAAAQAAJ&pg=PA155#v=onepage&q&f=false |date=2023-12-23 }}`{=mediawiki}, *Medical Times and Gazette*, 8 February 1873.
- Also see Brown, Isaac Baker. *On the Curability of Certain Forms of Insanity, Epilepsy, Catalepsy, and Hysteria in Females*. Robert Hardwicke, 1866.
Occasionally, in American and English medicine of the nineteenth century, circumcision was done as a cure for insanity. Some believed that mental and emotional disorders were related to female reproductive organs and that removing the clitoris would cure the neurosis. This treatment was discontinued in 1867.
Aesthetics may determine clitoral norms. A lack of ambiguity of the genitalia is seen as necessary in the assignment of a sex to infants and therefore whether a child\'s genitalia is normal, but what is considered ambiguous or normal can vary from person to person.
Sexual behavior is another reason for clitoridectomies. Author Sarah Rodriguez stated that the history of medical textbooks has indirectly created accepted ideas about the female body. Medical and gynecological textbooks are also at fault in the way that the clitoris is described in comparison to a male\'s penis. The importance and originality of a female\'s clitoris is underscored because it is seen as \"a less significant organ, since anatomy texts compared the penis and the clitoris in only one direction.\" Rodriguez said that a male\'s penis created the framework of the sexual organ.
Not all historical examples of clitoral surgeries should be assumed to be clitoridectomy (removal of the clitoris). In the nineteen thirties, the French psychoanalyst Marie Bonaparte studied African clitoral surgical practices and showed that these often involved removal of the clitoral hood, not the clitoris. She also had a surgery done to her own clitoris by the Viennese surgeon Dr Halban, which entailed cutting the suspensory ligament of the clitoris to permit it to sit closer to her vaginal opening. These sorts of clitoral surgeries, contrary to reducing women\'s sexual pleasure, actually appear aimed at making coitus more pleasurable for women, though it is unclear if that is ever their actual outcome.
### Human rights concerns {#human_rights_concerns}
Clitoridectomies are the most common form of female genital mutilation. The World Health Organization (WHO) estimates that clitoridectomies have been performed on 200 million girls and women that are currently alive. The regions that most clitoridectomies take place are Asia, the Middle East and west, north and east Africa. The practice also exists in migrants originating from these regions. Most of the surgeries are for cultural or religious reasons.
Clitoridectomy of people with conditions such as congenital adrenal hyperplasia that cause a clitoromegaly is controversial when it takes place during childhood or under duress. Many women who were exposed to such treatment have reported loss of physical sensation in the affected area, and loss of autonomy. In recent years, multiple human rights institutions have criticized early surgical management of such characteristics.
In 2013, it was disclosed in a medical journal that four unnamed elite female athletes from developing countries were subjected to gonadectomies and partial clitoridectomies after testosterone testing revealed that they had an intersex variation or disorder of sex development. In April 2016, the United Nations Special Rapporteur on health, Dainius Pūras, condemned this treatment as a form of genital mutilation \"in the absence of symptoms or health issues warranting those procedures
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# Cytochrome
**Cytochromes** are redox-active proteins containing a heme, with a central iron (Fe) atom at its core, as a cofactor. They are involved in the electron transport chain and redox catalysis. They are classified according to the type of heme and its mode of binding. Four varieties are recognized by the International Union of Biochemistry and Molecular Biology (IUBMB), cytochromes a, cytochromes b, cytochromes c and cytochrome d.
Cytochrome function is linked to the reversible redox change from ferrous (Fe(II)) to the ferric (Fe(III)) oxidation state of the iron found in the heme core. In addition to the classification by the IUBMB into four cytochrome classes, several additional classifications such as cytochrome o and cytochrome P450 can be found in biochemical literature.
## History
Cytochromes were initially described in 1884 by Charles Alexander MacMunn as respiratory pigments (myohematin or histohematin). In the 1920s, Keilin rediscovered these respiratory pigments and named them the cytochromes, or "cellular pigments". He classified these heme proteins on the basis of the position of their lowest energy absorption band in their reduced state, as cytochromes *a* (605 nm), *b* (≈565 nm), and *c* (550 nm). The ultra-violet (UV) to visible spectroscopic signatures of hemes are still used to identify heme type from the reduced bis-pyridine-ligated state, i.e., the pyridine hemochrome method. Within each class, cytochrome *a*, *b*, or *c*, early cytochromes are numbered consecutively, e.g. cyt *c*, cyt *c~1~*, and cyt *c~2~*, with more recent examples designated by their reduced state R-band maximum, e.g. cyt *c~559~*.
## Structure and function {#structure_and_function}
The heme group is a highly conjugated ring system (which allows its electrons to be very mobile) surrounding an iron ion. The iron in cytochromes usually exists in a ferrous (Fe^2+^) and a ferric (Fe^3+^) state with a ferroxo (Fe^4+^) state found in catalytic intermediates. Cytochromes are, thus, capable of performing electron transfer reactions and catalysis by reduction or oxidation of their heme iron. The cellular location of cytochromes depends on their function. They can be found as globular proteins and membrane proteins.
In the process of oxidative phosphorylation, a globular cytochrome cc protein is involved in the electron transfer from the membrane-bound complex III to complex IV. Complex III itself is composed of several subunits, one of which is a b-type cytochrome while another one is a c-type cytochrome. Both domains are involved in electron transfer within the complex. Complex IV contains a cytochrome a/a3-domain that transfers electrons and catalyzes the reaction of oxygen to water. Photosystem II, the first protein complex in the light-dependent reactions of oxygenic photosynthesis, contains a cytochrome b subunit. Cyclooxygenase 2, an enzyme involved in inflammation, is a cytochrome b protein.
In the early 1960s, a linear evolution of cytochromes was suggested by Emanuel Margoliash that led to the molecular clock hypothesis. The apparently constant evolution rate of cytochromes can be a helpful tool in trying to determine when various organisms may have diverged from a common ancestor.
## Types
Several kinds of cytochrome exist and can be distinguished by spectroscopy, exact structure of the heme group, inhibitor sensitivity, and reduction potential.
Four types of cytochromes are distinguished by their prosthetic groups:
Type Prosthetic group
-------------- ---------------------------------------------------
Cytochrome a heme A
Cytochrome b heme B
Cytochrome c heme C (covalently bound heme b)
Cytochrome d heme D (Heme B with γ-spirolactone){{Cite journal
There is no \"cytochrome e,\" but cytochrome f, found in the cytochrome b~6~f complex of plants is a c-type cytochrome.
In mitochondria and chloroplasts, these cytochromes are often combined in electron transport and related metabolic pathways:
Cytochromes Combination
---------------- --------------------------------------------------------------------------------------------------------------------
*a* and *a~3~* Cytochrome c oxidase (\"Complex IV\") with electrons delivered to complex by soluble cytochrome c (hence the name)
*b* and *c~1~* Coenzyme Q - cytochrome c reductase (\"Complex III\")
*b~6~* and *f* Plastoquinol---plastocyanin reductase
A distinct family of cytochromes is the cytochrome P450 family, so named for the characteristic Soret peak formed by absorbance of light at wavelengths near 450 nm when the heme iron is reduced (with sodium dithionite) and complexed to carbon monoxide. These enzymes are primarily involved in steroidogenesis and detoxification
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# Colin Kapp
**Derek Ivor Colin Kapp** (3 April 1928 -- 3 August 2007), Known as **Colin Kapp,** was a British science fiction author best known for his stories about the Unorthodox Engineers.
As an electronic engineer, he began his career with Mullard Electronics then specialised in electroplating techniques, eventually becoming a freelance consultant engineer.
He was born in Southwark, south London, 3 April 1928 to John L. F. Kapp and Annie M.A. (née Towner).
## Works
### Cageworld series {#cageworld_series}
1. *Search for the sun!* (1982) (also published as *Cageworld*)
2. *The Lost worlds of Cronus* (1982)
3. *The Tyrant of Hades* (1984)
4. *Star Search* (1984)
### Chaos series {#chaos_series}
- *The Patterns of Chaos* (1972)
- *The Chaos Weapon* (1977)
### Standalone novels {#standalone_novels}
- *The Dark Mind* (1964) (also published as *Transfinite Man*)
- *The Wizard of Anharitte* (1973)
- *The Survival Game* (1976)
- *Manalone* (1977)
- *The Ion War* (1978)
- *The Timewinders* (1980)
### Short stories {#short_stories}
#### Unorthodox Engineers {#unorthodox_engineers}
- \"The Railways Up on Cannis\" (1959)
- \"The Subways of Tazoo\" (1964)
- \"The Pen and the Dark\" (1966)
- \"Getaway from Getawehi\" (1969)
- \"The Black Hole of Negrav\" (1975)
Collected in *The Unorthodox Engineers* (1979)
#### Other stories {#other_stories}
- \"Breaking Point\" (1959)
- \"Survival Problem\" (1959)
- \"Lambda I\" (1962)
- \"The Night-Flame\" (1964)
- \"Hunger Over Sweet Waters\" (1965)
- \"Ambassador to Verdammt\" (1967)
- \"The Imagination Trap\" (1967)
- \"The Cloudbuilders\" (1968)
- \"[I Bring You Hands](https://archive.org/stream/Galaxy_v27n03_1968-10#page/n103/mode/2up)\" (1968)
- \"Gottlos\" (1969), notable for having (along with Keith Laumer\'s Bolo series) inspired Steve Jackson\'s classic game of 21st century tank warfare Ogre
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# Cathode ray
thumb\|upright=1.2\|A beam of cathode rays in a vacuum tube bent into a circle by a magnetic field generated by a Helmholtz coil. Cathode rays are normally invisible; in this demonstration Teltron tube, enough gas has been left in the tube for the gas atoms to luminesce when struck by the fast-moving electrons.
**Cathode rays** are streams of electrons observed in discharge tubes. If an evacuated glass tube is equipped with two electrodes and a voltage is applied, glass behind the positive electrode is observed to glow, due to electrons emitted from the cathode (the electrode connected to the negative terminal of the voltage supply). They were first observed in 1859 by German physicist Julius Plücker and Johann Wilhelm Hittorf, and were named in 1876 by Eugen Goldstein *Kathodenstrahlen*, or cathode rays. In 1897, British physicist J. J. Thomson showed that cathode rays were composed of a previously unknown negatively charged particle, which was later named the *electron*. Cathode-ray tubes (CRTs) use a focused beam of electrons deflected by electric or magnetic fields to render an image on a screen.
## Description
Cathode rays are so named because they are emitted by the negative electrode, or cathode, in a vacuum tube. To release electrons into the tube, they first must be detached from the atoms of the cathode. In the early experimental cold cathode vacuum tubes in which cathode rays were discovered, called Crookes tubes, this was done by using a high electrical potential of thousands of volts between the anode and the cathode to ionize the residual gas atoms in the tube. The positive ions were accelerated by the electric field toward the cathode, and when they collided with it they knocked electrons out of its surface; these were the cathode rays. Modern vacuum tubes use thermionic emission, in which the cathode is made of a thin wire filament which is heated by a separate electric current passing through it. The increased random heat motion of the filament knocks electrons out of the surface of the filament, into the evacuated space of the tube.
Since the electrons have a negative charge, they are repelled by the negative cathode and attracted to the positive anode. They travel in parallel lines through the empty tube. The voltage applied between the electrodes accelerates these low mass particles to high velocities. Cathode rays are invisible, but their presence was first detected in these Crookes tubes when they struck the glass wall of the tube, exciting the atoms of the glass and causing them to emit light, a glow called fluorescence. Researchers noticed that objects placed in the tube in front of the cathode could cast a shadow on the glowing wall, and realized that something must be traveling in straight lines from the cathode. After the electrons strike the back of the tube they make their way to the anode, then travel through the anode wire through the power supply and back through the cathode wire to the cathode, so cathode rays carry electric current through the tube.
The current in a beam of cathode rays through a vacuum tube can be controlled by passing it through a metal screen of wires (a grid) between cathode and anode, to which a small negative voltage is applied. The electric field of the wires deflects some of the electrons, preventing them from reaching the anode. The amount of current that gets through to the anode depends on the voltage on the grid. Thus, a small voltage on the grid can be made to control a much larger voltage on the anode. This is the principle used in vacuum tubes to amplify electrical signals. The triode vacuum tube developed between 1907 and 1914 was the first electronic device that could amplify, and is still used in some applications such as radio transmitters. High speed beams of cathode rays can also be steered and manipulated by electric fields created by additional metal plates in the tube to which voltage is applied, or magnetic fields created by coils of wire (electromagnets). These are used in cathode-ray tubes, found in televisions and computer monitors, and in electron microscopes.
` `[`File:Katódsugarak`](File:Katódsugarak)` mágneses mezőben(1).jpg|Crookes tube. The cathode (negative terminal) is on the right. The anode (positive terminal) is in the base of the tube at bottom. `\
` `[`File:Katódsugarak`](File:Katódsugarak)` mágneses mezőben(2).jpg|Cathode rays travel from the cathode at the rear of the tube, striking the glass front, making it glow green by ``fluorescence``. A metal cross in the tube casts a shadow, demonstrating that the rays travel in straight lines.`\
` `[`File:Katódsugarak`](File:Katódsugarak)` mágneses mezőben(3).jpg|A magnet creates a horizontal magnetic field through the neck of the tube, bending the rays up, so the green spot is higher.`\
` `[`File:Katódsugarak`](File:Katódsugarak)` mágneses mezőben(4).jpg|When the magnet is reversed, it bends the rays down, so the green spot is lower. The pink glow is caused by cathode rays striking residual gas atoms in the tube.`
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# Cathode ray
## History
After the invention of the vacuum pump in 1654 by Otto von Guericke, physicists began to experiment with passing high voltage electricity through rarefied air. In 1705, it was noted that electrostatic generator sparks travel a longer distance through low pressure air than through atmospheric pressure air.
### Gas discharge tubes {#gas_discharge_tubes}
thumb\|upright=1.1\|Geissler tube, in daylight and lit by its own light thumb\|upright=1.4\|Glow discharge in a low-pressure tube caused by electric current.
In 1838, Michael Faraday applied a high voltage between two metal electrodes at either end of a glass tube that had been partially evacuated of air, and noticed a strange light arc with its beginning at the cathode (negative electrode) and its end at the anode (positive electrode). In 1857, German physicist and glassblower Heinrich Geissler sucked even more air out with an improved pump, to a pressure of around 10^−3^ atm and found that, instead of an arc, a glow filled the tube. The voltage applied between the two electrodes of the tubes, generated by an induction coil, was anywhere between a few kilovolts and 100 kV. These were called Geissler tubes, similar to today\'s neon signs.
The explanation of these effects was that the high voltage accelerated free electrons and electrically charged atoms (ions) naturally present in the air of the tube. At low pressure, there was enough space between the gas atoms that the electrons could accelerate to high enough speeds that when they struck an atom they knocked electrons off of it, creating more positive ions and free electrons, which went on to create more ions and electrons in a chain reaction, known as a glow discharge. The positive ions were attracted to the cathode and when they struck it knocked more electrons out of it, which were attracted toward the anode. Thus the ionized air was electrically conductive and an electric current flowed through the tube.
Geissler tubes had enough air in them that the electrons could only travel a tiny distance before colliding with an atom. The electrons in these tubes moved in a slow diffusion process, never gaining much speed, so these tubes didn\'t produce cathode rays. Instead, they produced a colorful glow discharge (as in a modern neon light), caused when the electrons struck gas atoms, exciting their orbital electrons to higher energy levels. The electrons released this energy as light. This process is called fluorescence.
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# Cathode ray
## History
### Cathode rays {#cathode_rays}
By the 1870s, British physicist William Crookes and others were able to evacuate tubes to a lower pressure, below 10^−6^ atm. These were called Crookes tubes. Faraday had been the first to notice a dark space just in front of the cathode, where there was no luminescence. This came to be called the \"cathode dark space\", \"Faraday dark space\" or \"Crookes dark space\". Crookes found that as he pumped more air out of the tubes, the Faraday dark space spread down the tube from the cathode toward the anode, until the tube was totally dark. But at the anode (positive) end of the tube, the glass of the tube itself began to glow.
What was happening was that as more air was pumped from the tube, the electrons knocked out of the cathode when positive ions struck it could travel farther, on average, before they struck a gas atom. By the time the tube was dark, most of the electrons could travel in straight lines from the cathode to the anode end of the tube without a collision. With no obstructions, these low mass particles were accelerated to high velocities by the voltage between the electrodes. These were the cathode rays.
When they reached the anode end of the tube, they were traveling so fast that, although they were attracted to it, they often flew past the anode and struck the back wall of the tube. When they struck atoms in the glass wall, they excited their orbital electrons to higher energy levels. When the electrons returned to their original energy level, they released the energy as light, causing the glass to fluoresce, usually a greenish or bluish color. Later researchers painted the inside back wall with fluorescent chemicals such as zinc sulfide, to make the glow more visible.
Cathode rays themselves are invisible, but this accidental fluorescence allowed researchers to notice that objects in the tube in front of the cathode, such as the anode, cast sharp-edged shadows on the glowing back wall. In 1869, German physicist Johann Hittorf was first to realize that something must be traveling in straight lines from the cathode to cast the shadows. Eugen Goldstein named them *cathode rays* (German *Kathodenstrahlen*).
### Discovery of the electron {#discovery_of_the_electron}
thumb\|upright=1.3\|J. J, Thomson\'s electric deflection tube, in which he showed that a beam of cathode rays was bent by an electric field like matter particles. The cathode is on R. The electron beam is accelerated passing through the cylindrical high voltage anode (*center*), bent by a voltage on the deflection plates (*center L*), and strikes the back wall of the tube causing a luminous glow. At this time, atoms were the smallest particles known, and were believed to be indivisible. What carried electric currents was a mystery. During the last quarter of the 19th century, many historic experiments were done with Crookes tubes to determine what cathode rays were. There were two theories. Crookes and Arthur Schuster believed they were particles of \"radiant matter,\" that is, electrically charged atoms. German scientists Eilhard Wiedemann, Heinrich Hertz and Goldstein believed they were \"aether waves\", some new form of electromagnetic radiation, and were separate from what carried the electric current through the tube.
The debate was resolved in 1897 when J. J. Thomson measured the mass of cathode rays, showing they were made of particles, but were around 1800 times lighter than the lightest atom, hydrogen. Therefore, they were not atoms, but a new particle, the first *subatomic* particle to be discovered, which he originally called \"*corpuscle*\" but was later named *electron*, after particles postulated by George Johnstone Stoney in 1874. He also showed they were identical with particles given off by photoelectric and radioactive materials. It was quickly recognized that they are the particles that carry electric currents in metal wires, and carry the negative electric charge of the atom.
Thomson was given the 1906 Nobel Prize in Physics for this work. Philipp Lenard also contributed a great deal to cathode-ray theory, winning the Nobel Prize in 1905 for his research on cathode rays and their properties.
### Vacuum tubes {#vacuum_tubes}
The gas ionization (or cold cathode) method of producing cathode rays used in Crookes tubes was unreliable, because it depended on the pressure of the residual air in the tube. Over time, the air was absorbed by the walls of the tube, and it stopped working.
A more reliable and controllable method of producing cathode rays was investigated by Hittorf and Goldstein, and rediscovered by Thomas Edison in 1880. A cathode made of a wire filament heated red hot by a separate current passing through it would release electrons into the tube by a process called thermionic emission. The first true electronic vacuum tubes, invented in 1904 by John Ambrose Fleming, used this hot cathode technique, and they superseded Crookes tubes. These tubes didn\'t need gas in them to work, so they were evacuated to a lower pressure, around 10^−9^ atm (10^−4^ Pa). The ionization method of creating cathode rays used in Crookes tubes is today only used in a few specialized gas discharge tubes such as krytrons.
In 1906, Lee De Forest found that a small voltage on a grid of metal wires between the cathode and anode could control a current in a beam of cathode rays passing through a vacuum tube. His invention, called the triode, was the first device that could amplify electric signals, and revolutionized electrical technology, creating the new field of *electronics*. Vacuum tubes made radio and television broadcasting possible, as well as radar, talking movies, audio recording, and long-distance telephone service, and were the foundation of consumer electronic devices until the 1960s, when the transistor brought the era of vacuum tubes to a close.
Cathode rays are now usually called electron beams. The technology of manipulating electron beams pioneered in these early tubes was applied practically in the design of vacuum tubes, particularly in the invention of the cathode-ray tube (CRT) by Ferdinand Braun in 1897, which was used in television sets and oscilloscopes. Today, electron beams are employed in sophisticated devices such as electron microscopes, electron beam lithography and particle accelerators.
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# Cathode ray
## Properties of cathode rays and the experiments that revealed them {#properties_of_cathode_rays_and_the_experiments_that_revealed_them}
During the last quarter of the 19th century dozens of historic experiments were conducted to try to find out what cathode rays were. There were two theories: British scientists Crookes and Cromwell Varley believed they were particles of \'radiant matter\', that is, electrically charged atoms. German researchers E. Wiedemann, Heinrich Hertz, and Eugen Goldstein believed they were \'aether vibrations\', some new form of electromagnetic waves, and were separate from what carried the current through the tube. The debate continued until J. J. Thomson measured cathode ray's mass, proving they were a previously unknown negatively charged particle in an atom, the first subatomic particle, which he called a \'corpuscle\' but was later renamed the \'electron\'.
### Straight line motion {#straight_line_motion}
Julius Plücker in 1869 built a tube with an anode shaped like a Maltese Cross facing the cathode. It was hinged, so it could fold down against the floor of the tube. When the tube was turned on, the cathode rays cast a sharp cross-shaped shadow on the fluorescence on the back face of the tube, showing that the rays moved in straight lines. This fluorescence was used as an argument that cathode rays were electromagnetic waves, since the only thing known to cause fluorescence at the time was ultraviolet light. After a while the fluorescence would get \'tired\' and the glow would decrease. If the cross was folded down out of the path of the rays, it no longer cast a shadow, and the previously shadowed area would fluoresce more strongly than the area around it.
### Perpendicular emission {#perpendicular_emission}
thumb\|upright=0.4\|Crookes tube with concave cathode Eugen Goldstein in 1876 found that cathode rays were always emitted perpendicular to the cathode\'s surface. If the cathode was a flat plate, the rays were shot out in straight lines perpendicular to the plane of the plate. This was evidence that they were particles, because a luminous object, like a red hot metal plate, emits light in all directions, while a charged particle will be repelled by the cathode in a perpendicular direction. Cathode rays heat matter which they strike. If the electrode was made in the form of a concave spherical dish, the cathode rays would be focused to a spot in front of the dish. This could be used to heat samples to a high temperature. `{{breakafterimages}}`{=mediawiki}
### Electrostatic deflection {#electrostatic_deflection}
Cathode rays path can be deflected by an electric field. Heinrich Hertz built a tube with a second pair of metal plates to either side of the cathode ray beam, a crude CRT. If the cathode rays were charged particles, their path should be bent by the electric field created when a voltage was applied to the plates, causing the spot of light where the rays hit to move sideways. He did not find any bending, but it was later determined that his tube was insufficiently evacuated, causing accumulations of surface charge which masked the electric field. Later Arthur Schuster repeated the experiment with a higher vacuum. He found that the rays were attracted toward a positively charged plate and repelled by a negative one, bending the beam. This was evidence they were negatively charged, and therefore not electromagnetic waves. `{{breakafterimages}}`{=mediawiki}
### Magnetic deflection {#magnetic_deflection}
thumb\|Crookes magnetic deflection tube The rays path can be deflected by a magnetic field. Crookes put a magnet across the neck of the tube, so that the North pole was on one side of the beam and the South pole was on the other, and the beam travelled through the magnetic field between them. The beam was bent down, perpendicular to the magnetic field. To reveal the path of the beam, Crookes invented a tube *(see pictures)* with a cardboard screen with a phosphor coating down the length of the tube, at a slight angle so the electrons would strike the phosphor along its length, making a glowing line on the screen. The line could be seen to bend up or down in a transverse magnetic field. This effect (now called the Lorentz force) was similar to the behavior of electric currents in an electric motor and showed that the cathode rays obeyed Faraday\'s law of induction like currents in wires. Both electric and magnetic deflection were evidence for the particle theory, because electric and magnetic fields have no effect on a beam of light waves in vacuum.
### Paddlewheel
thumb\|Crookes\'s paddlewheel tube, from his 1879 paper *On Radiant Matter* Crookes put a tiny vaned turbine or paddlewheel in the path of the cathode rays, and found that it rotated when the rays hit it. The paddlewheel turned in a direction away from the cathode side of the tube, suggesting that the force of the cathode rays striking the paddles was causing the rotation. Crookes concluded at the time that this showed that cathode rays had momentum, so the rays were likely matter particles. However, later it was concluded that the paddle wheel turned not due to the momentum of the particles (or electrons) hitting the paddle wheel but due to the radiometric effect. When the rays hit the paddle surface they heated it, and the heat caused the gas next to it to expand, pushing the paddle. This was proven in 1903 by J. J. Thomson who calculated that the momentum of the electrons hitting the paddle wheel would only be sufficient to turn the wheel one revolution per minute. All this experiment really showed was that cathode rays were able to heat surfaces.
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# Cathode ray
## Properties of cathode rays and the experiments that revealed them {#properties_of_cathode_rays_and_the_experiments_that_revealed_them}
### Negative electric charge {#negative_electric_charge}
Jean-Baptiste Perrin wanted to determine whether the cathode rays actually carried negative charge, or whether they just accompanied the charge carriers, as the Germans thought. In 1895 he constructed a tube with a \'catcher\', a closed aluminum cylinder with a small hole in the end facing the cathode, to collect the cathode rays. The catcher was attached to an electroscope to measure its charge. The electroscope showed a negative charge, proving that cathode rays really carry negative electricity.
### Anode rays {#anode_rays}
thumb\|upright=0.75\|Special tube with perforated cathode, producing anode rays *(top, pink)* Goldstein found in 1886 that if the cathode is made with small holes in it, streams of a faint luminous glow will be seen issuing from the holes on the back side of the cathode, facing away from the anode. It was found that in an electric field these anode rays bend in the opposite direction from cathode rays, toward a negatively charged plate, indicating that they carry a positive charge. These were the positive ions which were attracted to the cathode, and created the cathode rays. They were named *canal rays* (*Kanalstrahlen*) by Goldstein.
### Spectral shift {#spectral_shift}
Eugen Goldstein thought he had figured out a method of measuring the speed of cathode rays. If the glow discharge seen in the gas of Crookes tubes was produced by the moving cathode rays, the light radiated from them in the direction they were moving, down the tube, would be shifted in frequency due to the Doppler effect. This could be detected with a spectroscope because the emission line spectrum would be shifted. He built a tube shaped like an \"L\", with a spectroscope pointed through the glass of the elbow down one of the arms. He measured the spectrum of the glow when the spectroscope was pointed toward the cathode end, then switched the power supply connections so the cathode became the anode and the electrons were moving in the other direction, and again observed the spectrum looking for a shift. He did not find one, which he calculated meant that the rays were traveling very slowly. It was later recognized that the glow in Crookes tubes is emitted from gas atoms hit by the electrons, not the electrons themselves. Since the atoms are thousands of times more massive than the electrons, they move much slower, accounting for the lack of Doppler shift.
### Lenard window {#lenard_window}
thumb\|Lenard window tube Philipp Lenard wanted to see if cathode rays could pass out of the Crookes tube into the air. See diagram. He built a tube with a \"window\" *(W)* in the glass envelope made of aluminum foil just thick enough to hold the atmospheric pressure out (later called a \"Lenard window\") facing the cathode *(C)* so the cathode rays would hit it. He found that something did come through. Holding a fluorescent screen up to the window caused it to fluoresce, even though no light reached it. A photographic plate held up to it would be darkened, even though it was not exposed to light. The effect had a very short range of about 2.5 cm. He measured the ability of cathode rays to penetrate sheets of material, and found they could penetrate much farther than moving atoms could. Since atoms were the smallest particles known at the time, this was first taken as evidence that cathode rays were waves. Later it was realized that electrons were much smaller than atoms, accounting for their greater penetration ability. Lenard was awarded the Nobel Prize in Physics in 1905 for his work.
### Wave-particle duality {#wave_particle_duality}
Louis de Broglie later (1924) suggested in his doctoral dissertation that electrons are like photons and can act as waves. The wave-like behaviour of cathode rays was later directly demonstrated using reflection from a nickel surface by Davisson and Germer, and transmission through celluloid thin films and later metal films by George Paget Thomson and Alexander Reid in 1927. (Alexander Reid, who was Thomson\'s graduate student, performed the first experiments but he died soon after in a motorcycle accident and is rarely mentioned
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# Chrominance
**Chrominance** (*chroma* or *C* for short) is the signal used in video systems to convey the color information of the picture (see YUV color model), separately from the accompanying luma signal (or Y\' for short). Chrominance is usually represented as two color-difference components: U = B′ − Y′ (blue − luma) and V = R′ − Y′ (red − luma). Each of these different components may have scale factors and offsets applied to it, as specified by the applicable video standard.
In composite video signals, the U and V signals modulate a color subcarrier signal, and the result is referred to as the chrominance signal; the phase and amplitude of this modulated chrominance signal correspond approximately to the hue and saturation of the color. In digital-video and still-image color spaces such as Y′CbCr, the luma and chrominance components are digital sample values.
Separating RGB color signals into luma and chrominance allows the bandwidth of each to be determined separately. Typically, the chrominance bandwidth is reduced in analog composite video by reducing the bandwidth of a modulated color subcarrier, and in digital systems by chroma subsampling.
## History
The idea of transmitting a color television signal with distinct luma and chrominance components originated with Georges Valensi, who patented the idea in 1938. Valensi\'s patent application described:
> The use of two channels, one transmitting the predominating color (signal T), and the other the mean brilliance (signal t) output from a single television transmitter to be received not only by color television receivers provided with the necessary more expensive equipment, but also by the ordinary type of television receiver which is more numerous and less expensive and which reproduces the pictures in black and white only.
Previous schemes for color television systems, which were incompatible with existing monochrome receivers, transmitted RGB signals in various ways.
## Television standards {#television_standards}
In analog television, chrominance is encoded into a video signal using a subcarrier frequency. Depending on the video standard, the chrominance subcarrier may be either quadrature-amplitude-modulated (NTSC and PAL) or frequency-modulated (SECAM).
In the PAL system, the color subcarrier is 4.43 MHz above the video carrier, while in the NTSC system it is 3.58 MHz above the video carrier. The NTSC and PAL standards are the most commonly used, although there are other video standards that employ different subcarrier frequencies. For example, PAL-M (Brazil) uses a 3.58 MHz subcarrier, and SECAM uses two different frequencies, 4.250 MHz and 4.40625 MHz above the video carrier.
The presence of chrominance in a video signal is indicated by a color burst signal transmitted on the back porch, just after horizontal synchronization and before each line of video starts. If the color burst signal were visible on a television screen, it would appear as a vertical strip of a very dark olive color. In NTSC and PAL, hue is represented by a phase shift of the chrominance signal relative to the color burst, while saturation is determined by the amplitude of the subcarrier. In SECAM (R′ − Y′) and (B′ − Y′) signals are transmitted alternately and phase does not matter.
Chrominance is represented by the U-V color plane in PAL and SECAM video signals, and by the I-Q color plane in NTSC.
## Digital systems {#digital_systems}
Digital video and digital still photography systems sometimes use a luma/chroma decomposition for improved compression. For example, when an ordinary RGB digital image is compressed via the JPEG standard, the RGB color space is first converted (by a rotation matrix) to a YCbCr color space, because the three components in that space have less correlation redundancy and because the chrominance components can then be subsampled by a factor of 2 or 4 to further compress the image. On decompression, the Y′CbCr space is rotated back to RGB
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# Campus
A **campus** traditionally refers to the land and buildings of a college or university. This will often include libraries, lecture halls, student centers and, for residential universities, residence halls and dining halls.
By extension, a **corporate campus** is a collection of buildings and grounds that belong to a company, particularly in the technology sector. Examples include Bell Labs, the Googleplex and Apple Park.
## Etymology
Campus comes from the *campus*, meaning \"field\", and was first used in the academic sense at Princeton University in 1774. At Princeton, the word referred to a large open space on the college grounds; similarly at the University of South Carolina it was used by 1826 to describe the open square (of around 10 acres) between the college buildings. By the end of the 19th century, the term was used widely at US colleges to refer to the grounds of the college, but it was not until the 20th century that it expanded to include the buildings as well.
## History
The tradition of a campus began with the medieval European universities where the students and teachers lived and worked together in a cloistered environment. The notion of the importance of the setting to academic life later migrated to America, and early colonial educational institutions were based on the Scottish and English collegiate system.
The campus evolved from the cloistered model in Europe to a diverse set of independent styles in the United States. Early colonial colleges were all built in proprietary styles, with some contained in single buildings, such as the campus of Princeton University or arranged in a version of the cloister reflecting American values, such as Harvard\'s. Both the campus designs and the architecture of colleges throughout the country have evolved in response to trends in the broader world, with most representing several different contemporary and historical styles and arrangements.
In 1922, a lecture by Patrick Abercrombie at the British Town Planning Institute contrasted the American campus to the style of Oxbridge colleges, saying: \"generally with us the park-like garden and trees are to one side of the college buildings, in contrast with the formally enclosed quad with its clipt grass. In the Campus method the departments of the university are scattered about a park and are actually among the trees.\" However, he did also note that Trinity College Dublin had \"what is called elsewhere a Campus\" on its 28 acre site in central Dublin, and that William Wilkins had \"attempt\[ed\] an English Campus\" on the 20 acre site of Downing College, Cambridge.
The first true campus universities in Britain were not established until the late 1940s, with the University of Reading moving to its Whiteknights campus in 1947, University College Swansea (now Swansea University) moving to its Singleton Park campus in 1948 and the University College of North Staffordshire (now the University of Keele) being established on the Keele Hall estate in 1949.
## Uses
### Office buildings {#office_buildings}
In the early 1990s the term began to be used to describe a company\'s office building complex, most notably when Apple\'s Infinite Loop campus was first built, which at the time was exclusively for research and development. The Microsoft Campus in Redmond, Washington, is another example of this usage, although it was built in the 1980s, before the term was applied to company property. In the 21st century, hospitals and even airports sometimes use the term to describe the territory of their respective facilities.
### Universities
The word *campus* has also been applied to European universities, although some such institutions (in particular, \"ancient\" universities such as Bologna, Padua, Oxford and Cambridge) are characterized by ownership of individual buildings in university town-like urban settings rather than sprawling park-like lawns in which buildings are placed.
## World Heritage campuses {#world_heritage_campuses}
A number of university campuses or parts of campuses have been recognised as World Heritage Sites by UNESCO for their outstanding universal value
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# Chalcedonian Definition
The **Chalcedonian Definition** (also called the **Chalcedonian Creed** or the **Definition of Chalcedon**) is the declaration of the dyophysitism of Christ\'s nature, adopted at the Council of Chalcedon in AD 451. Chalcedon was an early centre of Christianity located in Asia Minor. The council was the fourth of the ecumenical councils that are accepted by Chalcedonian churches which include the Catholic and Orthodox churches.
It was the first council not to be recognised by any Oriental Orthodox church; for this reason these churches may be classified as Non-Chalcedonian.
## Context
The Council of Chalcedon was summoned to consider the Christological question in light of the \"one-nature\" view of Christ proposed by Eutyches, archimandrite at Constantinople, which prevailed at the Second Council of Ephesus in 449, sometimes referred to as the \"Robber Synod\".
The Council first solemnly ratified the Nicene Creed adopted in 325 and that creed as amended by the First Council of Constantinople in 381. It also confirmed the authority of two synodical letters of Cyril of Alexandria and the letter of Pope Leo I to Flavian of Constantinople.
## Content
The full text of the definition reaffirms the decisions of the Council of Ephesus, the pre-eminence of the Creed of Nicaea (325) and the further definitions of the Council of Constantinople (381).
In one of the translations into English, the key section, emphasizing the double nature of Christ (human and divine), runs: `{{Blockquote|Following, then, the holy Fathers, we all unanimously teach that our Lord Jesus Christ is to us One and the same Son, the Self-same Perfect in Godhead, the Self-same Perfect in Manhood; ''truly God and truly Man''; the Self-same of a rational soul and body; co-essential with the Father according to the Godhead, the Self-same co-essential with us according to the Manhood; like us in all things, sin apart; before the ages begotten of the Father as to the Godhead, but in the last days, the Self-same, for us and for our salvation (born) of Mary the Virgin [[Theotokos]] as to the Manhood; One and the Same Christ, Son, Lord, Only-begotten; acknowledged in Two Natures unconfusedly, unchangeably, indivisibly, inseparably; the difference of the Natures being in no way removed because of the Union, but rather the properties of each Nature being preserved, and (both) concurring into One Person and One Hypostasis; not as though He was parted or divided into Two Persons, but One and the Self-same Son and Only-begotten God, Word, Lord, Jesus Christ; even as from the beginning the prophets have taught concerning Him, and as the Lord Jesus Christ Himself hath taught us, and as the Symbol of the Fathers hath handed down to us.|source={{harvnb|Bindley|1899|p=297}} }}`{=mediawiki}
The Definition implicitly addressed a number of popular heretical beliefs. The reference to \"co-essential with the Father\" was directed at Arianism; \"co-essential with us\" is directed at Apollinarianism; \"Two Natures unconfusedly, unchangeably\" refutes Eutychianism; and \"indivisibly, inseparably\" and \"Theotokos\" are against Nestorianism.
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# Chalcedonian Definition
## Oriental Orthodox dissent {#oriental_orthodox_dissent}
The Chalcedonian Definition was written amid controversy between the Western and Eastern churches over the meaning of the Incarnation (see Christology). The Western church readily accepted the creed, but some Eastern churches did not. Political disturbances prevented the Armenian bishops from attending. Even though Chalcedon reaffirmed the Third Council\'s condemnation of Nestorius, the Non-Chalcedonians always suspected that the Chalcedonian Definition tended towards Nestorianism. This was in part because of the restoration of a number of bishops deposed at the Second Council of Ephesus, bishops who had previously indicated what appeared to be support of Nestorian positions.
The Coptic Church of Alexandria dissented, holding to Cyril of Alexandria\'s preferred formula for the oneness of Christ\'s nature in the incarnation of God the Word as \"out of two natures\". Cyril\'s language is not consistent and he may have countenanced the view that it is possible to contemplate in theory two natures after the incarnation, but the Church of Alexandria felt that the Definition should have stated that Christ be acknowledged \"out of two natures\" rather than \"in two natures\".
The definition defines that Christ is \"acknowledged in two natures\", which \"come together into one person and one hypostasis\". The formal definition of \"two natures\" in Christ was understood by the critics of the council at the time, and is understood by many historians and theologians today, to side with western and Antiochene Christology and to diverge from the teaching of Cyril of Alexandria, who always stressed that Christ is \"one\". However, a modern analysis of the sources of the creed (by A. de Halleux, in *Revue Theologique de Louvain* 7, 1976) and a reading of the acts, or proceedings, of the council show that the bishops considered Cyril the great authority and that even the language of \"two natures\" derives from him.
This miaphysite position, historically characterised by Chalcedonian followers as \"monophysitism\", though this is denied by the dissenters, formed the basis for the distinction of the Coptic Church of Egypt and Ethiopia and the \"Jacobite\" churches of Syria, and the Armenian Apostolic Church (see Oriental Orthodoxy) from other churches
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# Car Talk
***Car Talk*** is a metonym for the humorous work of \"Click and Clack, the Tappet Brothers\", Tom and Ray Magliozzi, on automobile repair. Originally, *Car Talk* was a radio show that ran on National Public Radio (NPR) from 1977 until October 2012, when the Magliozzi brothers retired. Since their retirement, the oeuvre now includes a website and a podcast of reruns that is currently hosted by Apple Podcasts, NPR Podcasts, and Stitcher. The *Car Talk* radio show was honored with a Peabody Award in 1992, and the Magliozzis were both inducted into the National Radio Hall of Fame in 2014 and the Automotive Hall of Fame in 2018.
## Premise
*Car Talk* was presented in the form of a call-in radio show: listeners called in with questions related to motor vehicle maintenance and repair. Most of the advice sought was diagnostic, with callers describing symptoms and demonstrating sounds of an ailing vehicle while the Magliozzis made an attempt to identify the malfunction over the telephone and give advice on how to fix it. While the hosts peppered their call-in sessions with jokes directed at both the caller and at themselves, the Magliozzis were usually able to arrive at a diagnosis. However, when they were stumped, they attempted anyway with an answer they claimed was \"unencumbered by the thought process\", the official motto of the show.
Edited reruns are carried on XM Satellite Radio (now Sirius XM) via both the Public Radio and NPR Now channels.
The *Car Talk* theme music is \"Dawggy Mountain Breakdown\" by bluegrass artist David Grisman.
### Call-in procedure {#call_in_procedure}
Throughout the program, listeners were encouraged to dial the toll-free telephone number, 1-888-CAR-TALK (1-888-227-8255), which connected to a 24-hour answering service. Although the approximately 2,000 queries received each week were screened by the *Car Talk* staff, the questions were unknown to the Magliozzis in advance as \"that would entail researching the right answer, which is what? \... Work.\"
### Features
The show originally consisted of two segments with a break in between but was changed to three segments. After the shift to the three-segment format, it became a running joke to refer to the last segment as \"the third half\" of the program.
The show opened with a short comedy segment, typically jokes sent in by listeners, followed by eight call-in sessions. The hosts ran a contest called the \"Puzzler\", in which a riddle, sometimes car-related, was presented. The answer to the previous week\'s \"Puzzler\" was given at the beginning of the \"second half\" of the show, and a new \"Puzzler\" was given at the start of the \"third half\". The hosts gave instructions to listeners to write answers addressed to \"Puzzler Tower\" on some non-existent or expensive object, such as a \"\$26 bill\" or an advanced DSLR camera. This gag initially started as suggestions that the answers be written \"on the back of a \$20 bill\". A running gag concerned Tom\'s inability to remember the previous week\'s \"Puzzler\" without heavy prompting from Ray. During a tribute show following Tom\'s death in 2014 due to complications of Alzheimer\'s disease, Ray joked, \"I guess he wasn\'t joking about not being able to remember the puzzler all those years.\" For each puzzler, one correct answer was chosen at random, with the winner receiving a \$26 gift certificate to the *Car Talk* store, referred to as the \"Shameless Commerce Division\". It was originally \$25, but was increased for inflation after a few years. Originally, the winner received a specific item from the store, but it soon changed to a gift certificate to allow the winner to choose the item they wanted (though Tom often made an item suggestion).
A recurring feature was \"Stump the Chumps,\" in which the hosts revisited a caller from a previous show to determine the accuracy and the effect, if any, of their advice. A similar feature began in May 2001, \"Where Are They Now, Tommy?\" It began with a comical musical theme with a sputtering, backfiring car engine and a horn as a backdrop. Tom then announced who the previous caller was, followed by a short replay of the essence of the previous call, preceded and followed by harp music often used in other audiovisual media to indicate recalling and returning from a dream. The hosts then greeted the previous caller, confirmed that they had not spoken since their previous appearance and asked them if there had been any influences on the answer they were about to relate, such as arcane bribes by the NPR staff. The repair story was then discussed, followed by a fanfare and applause if the Tappet Brothers\' diagnosis was correct, or a wah-wah-wah music piece mixed with a car starter operated by a weak battery (an engine which wouldn\'t start) if the diagnosis was wrong. The hosts then thanked the caller for their return appearance.
The brothers also had an official Animal-Vehicle Biologist and Wildlife Guru named Kieran Lindsey. She answered questions like \"How do I remove a snake from my car?\" and offered advice on how those living in cities and suburbs could reconnect with wildlife. They also would sometimes rely on Harvard University professors Wolfgang Rueckner and Jim E. Davis for questions concerning physics and chemistry, respectively.
There were numerous appearances from NPR personalities, including Bob Edwards, Susan Stamberg, Scott Simon, Ray Suarez, Will Shortz, Sylvia Poggioli, and commentator and author Daniel Pinkwater. On one occasion, the show featured Martha Stewart as an in-studio guest, whom the Magliozzis twice during the segment referred to as \"Margaret\". Celebrities and public figures were featured as \"callers\" as well, including Geena Davis, Ashley Judd, Morley Safer, Gordon Elliott, former Major League Baseball pitcher Bill Lee, journalist Farhad Manjoo, and astronaut John M. Grunsfeld.
#### Space program calls {#space_program_calls}
Astronaut and engineer John Grunsfeld called into the show during Space Shuttle mission STS-81 in January 1997, in which *Atlantis* docked to the Mir space station. In this call he complained about the performance of his serial-numbered, Rockwell-manufactured \"government van\". To wit, it would run very loud and rough for about two minutes, quieter and smoother for another six and a half, and then the engine would stop with a jolt. He went on to state that the brakes of the vehicle, when applied, would glow red-hot, and that the vehicle\'s odometer displayed \"about 60 million miles\". This created some consternation for the hosts, until they noticed the audio of Grunsfeld\'s voice, being relayed from Mir via TDRS satellite, sounded similar to that of Tom Hanks in the then-recent film Apollo 13, after which they realized the call was from space and the government van in question was, in fact, the Space Shuttle.
In addition to the on-orbit call, the Brothers once received a call asking advice on winterizing an electric car. When they asked what kind of car, the caller stated it was a \"kit car\", a \$400 million \"kit car\". It was a joke call from NASA\'s Jet Propulsion Laboratory concerning the preparation of the Mars *Opportunity* rover for the oncoming Martian winter, during which temperatures drop to several hundred degrees below freezing.
Click and Clack have also been featured in editorial cartoons, including one where a befuddled NASA engineer called them to ask how to fix the Space Shuttle.
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# Car Talk
## Premise
### Humor
Humor and wisecracking pervaded the program. Tom and Ray are known for their self-deprecating humor, often joking about the supposedly poor quality of their advice and the show in general. They also commented at the end of each show: \"Well, it\'s happened again---you\'ve wasted another perfectly good hour listening to *Car Talk*.\"
The phrase \"our fair city\" was introduced during a puzzler segment on the radio show. Ray presented a puzzler involving a well-dressed man who referred to a city as \"your fair city.\" Tom found the phrase amusing and began using it humorously to refer to Cambridge, Massachusetts, where the show was based. This playful reference quickly became a running joke on the show, with the hosts frequently referring to Cambridge as \"our fair city\" in subsequent episodes. In another episode Ray mentioned Cambridge, Massachusetts, at which point Tom reverently interjected with a tone of civic pride, \"Our fair city\". Ray invariably mocked {{\"\'}}Cambridge, MA\', the United States Postal Service\'s two-letter abbreviation for \'Massachusetts{{\'\"}}, by pronouncing the \"MA\" as a word.. This also became a running gag.
Preceding each break in the show, one of the hosts led up to the network identification with a humorous take on a disgusted reaction of some usually famous person to hearing that identification. The full line went along the pattern of, for example, \"And even though Roger Clemens stabs his radio with a syringe whenever he hears *us* say it, this is NPR: National Public Radio\" (later just \"\... this is NPR\").
At one point in the show, often after the break, Ray usually stated that: \"Support for this show is provided by,\" followed by an absurd fundraiser.
The ending credits of the show started with thanks to the colorfully nicknamed actual staffers: producer Doug \"the subway fugitive, not a slave to fashion, bongo boy frogman\" Berman; \"John \'Bugsy\' Lawlor, just back from the \...\" every week a different eating event with rhyming foodstuff names; David \"Calves of Belleville\" Greene; Catherine \"Frau Blücher\" Fenollosa, whose name caused a horse to neigh and gallop (an allusion to a running gag in the movie *Young Frankenstein*); and Carly \"High Voltage\" Nix, among others. Following the real staff was a lengthy list of pun-filled fictional staffers and sponsors such as statistician Marge Innovera (\"margin of error\"), customer care representative Haywood Jabuzoff (\"Hey, would ya buzz off\"), meteorologist Claudio Vernight (\"cloudy overnight\"), optometric firm C. F. Eye Care (\"see if I care\"), Russian chauffeur Picov Andropov (\"pick up and drop off\"), Leo Tolstoy biographer Warren Peace (\"War and Peace\"), hygiene officer and chief of the Tokyo office Oteka Shawa (\"oh, take a shower\"), Swedish snowboard instructor Soren Derkeister (\"sore in the keister\"), law firm Dewey, Cheetham & Howe (\"Do we cheat \'em? And how!\"), Greek tailor Euripides Eumenades (\"You rip-a these, you mend-a these\"), cloakroom attendant Mahatma Coate (\"My hat, my coat\"), seat cushion tester Mike Easter (my keister) and many, many others, usually concluding with Erasmus B. Dragon (\"Her ass must be draggin{{\'\"}}), whose job title varied, but who was often said to be head of the show\'s working mothers\' support group. They sometimes advised that \"our chief counsel from the law firm of Dewey, Cheetham, & Howe is Hugh Louis Dewey, known to a group of people in Harvard Square as Huey Louie Dewey.\" (Huey, Louie, and Dewey were the juvenile nephews being raised by Donald Duck in *Walt Disney\'s Comics and Stories*.) Guest accommodations were provided by The Horseshoe Road Inn (\"the horse you rode in\").
At the end of the show, Ray warns the audience, \"Don\'t drive like my brother!\" to which Tom replies, \"And don\'t drive like *my* brother!\" The original tag line was \"Don\'t drive like a knucklehead!\" There were variations such as, \"Don\'t drive like my brother \...\" \"And don\'t drive like his brother!\" and \"Don\'t drive like my sister \...\" \"And don\'t drive like *my* sister!\" The tagline was heard in the Pixar film *Cars*, in which Tom and Ray voiced anthropomorphized vehicles (Rusty and Dusty Rust-eze, respectively a 1963 Dodge Dart and 1963 Dodge A100 van, as Lightning McQueen\'s racing sponsors) with personalities similar to their own on-air personae. Tom notoriously once owned a \"convertible, green with large areas of rust!\" Dodge Dart, known jokingly on the program by the faux-elegant name \"Dartre\".
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# Car Talk
## History
In 1977, radio station WBUR-FM in Boston scheduled a panel of local car mechanics to discuss car repairs on one of its programs, but only Tom Magliozzi showed up. He did so well that he was asked to return as a guest, and he invited his younger brother Ray (who was actually more of a car repair expert) to join him. The brothers were soon asked to host their own radio show on WBUR, which they continued to do every week. In 1986, NPR decided to distribute their show nationally.
In 1989, the brothers started a newspaper column *Click and Clack Talk Cars* which, like the radio show, mixed serious advice with humor. King Features distributes the column. Ray Magliozzi continues to write the column, retitled *Car Talk*, after his brother\'s death in 2014, knowing he would have wanted the advice and humor to continue.
In 1992, *Car Talk* won a Peabody Award, saying \"Each week, master mechanics Tom and Ray Magliozzi provide useful information about preserving and protecting our cars. But the real core of this program is what it tells us about human mechanics \... The insight and laughter provided by Messrs. Magliozzi, in conjunction with their producer Doug Berman, provide a weekly mental tune-up for a vast and ever-growing public radio audience.\"
In 2005, Tom and Ray Magliozzi founded the Car Talk Vehicle Donation Program, \"as a way to give back to the stations that were our friends and partners for decades --- and whose programs we listen to every day.\" Since the Car Talk Vehicle Donation Program was founded, over 40,000 vehicles have been donated to support local NPR stations and programs, with over \$40 million donated. Approximately 70% of the proceeds generated go directly toward funding local NPR affiliates and programs.
As of 2012, it had 3.3 million listeners each week, on about 660 stations. On June 8, 2012, the brothers announced that they would no longer broadcast new episodes as of October. Executive producer Doug Berman said the best material from 25 years of past shows would be used to put together \"repurposed\" shows for NPR to broadcast. Berman estimated the archives contain enough for eight years\' worth of material before anything would have to be repeated. Ray Magliozzi, however, would occasionally record new taglines and sponsor announcements that were aired at the end of the show.
The show was inducted into the National Radio Hall of Fame in 2014.
Ray Magliozzi hosted a special *Car Talk* memorial episode for his brother Tom after he died in November 2014.
The *Best of Car Talk* episodes ended their weekly broadcast on NPR on September 30, 2017, although past episodes would continue availability online and via podcasts. 120 of the 400 stations intended to continue airing the show. NPR announced one option for the time slot would be their new news-talk program *It\'s Been a Minute*.
On June 11, 2021, it was announced that radio distribution of *Car Talk* would officially end on October 1, 2021, and that NPR would begin distribution of a twice-weekly podcast that will be 35--40 minutes in length and include early versions of every show, in sequential order.
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# Car Talk
## Hosts
The Magliozzis were long-time auto mechanics. Ray Magliozzi has a Bachelor of Science degree in humanities and science from MIT, while Tom had a Bachelor of Science degree in economics from MIT, an MBA from Northeastern University, and a DBA from the Boston University School of Management.
The Magliozzis operated a do-it-yourself garage together in the 1970s which became more of a conventional repair shop in the 1980s. Ray continued to have a hand in the day-to-day operations of the shop for years, while his brother Tom semi-retired, often joking on *Car Talk* about his distaste for doing \"actual work\". The show\'s offices were located near their shop at the corner of JFK Street and Brattle Street in Harvard Square, marked as \"Dewey, Cheetham & Howe\", the imaginary law firm to which they referred on-air. DC&H doubled as the business name of Tappet Brothers Associates, the corporation established to manage the business end of *Car Talk*. Initially a joke, the company was incorporated after the show expanded from a single station to national syndication.
The two were commencement speakers at MIT in 1999.
Executive producer Doug Berman said in 2012, \"The guys are culturally right up there with Mark Twain and the Marx Brothers. They will stand the test of time. People will still be enjoying them years from now. They\'re that good.\"
Tom Magliozzi died on November 3, 2014, at age 77, due to complications from Alzheimer\'s disease.
## Adaptations
The show was the inspiration for the short-lived *The George Wendt Show*, which briefly aired on CBS in the 1994--1995 season as a mid-season replacement.
In July 2007, PBS announced that it had green-lit an animated adaptation of *Car Talk*, to air on prime-time in 2008. The show, titled *Click and Clack\'s As the Wrench Turns*, is based on the adventures of the fictional \"Click and Clack\" brothers\' garage at \"Car Talk Plaza\". The ten episodes aired in July and August 2008.
*Car Talk: The Musical!!!* was written and directed by Wesley Savick, and composed by Michael Wartofsky. The adaptation was presented by Suffolk University, and opened on March 31, 2011, at the Modern Theatre in Boston, Massachusetts. The play was not officially endorsed by the Magliozzis, but they participated in the production, lending their voices to a central puppet character named \"The Wizard of Cahs\"
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# Chuck-a-luck
**Chuck-a-luck**, also known as **birdcage**, or **sweat rag**, is a game of chance played with three dice. It is derived from grand hazard and both can be considered a variant of sic bo, which is a popular casino game, although chuck-a-luck is more of a carnival game than a true casino game. The game is sometimes used as a fundraiser for charity.
## Rules
Chuck-a-luck is played with three standard six-sided, numbered dice that are kept in a device shaped somewhat like an hourglass which resembles a wire-frame bird cage and pivots about its centre. The dealer rotates the cage end over end, with the dice landing on the bottom.
Wagers are placed based on possible combinations that can appear on the three dice. The possible wagers are usually fewer than the wagers that are possible in sic bo and, in that sense, chuck-a-luck can be considered to be a simpler game. In the simplest variant, bettors place stakes on a board with six numbered spaces, labelled 1 through 6, inclusive. They receive a 1:1 payout if the number bet on appears once, a 2:1 payout if the number appears twice, and a 3:1 payout if the number is rolled all 3 times. In this respect, the basic game is identical to Crown and Anchor, but with numbered dice instead of symbols.
Additional wagers that are commonly seen, and their associated odds, are set out in the table below.
+----------------+------------------------------------------------------------------------------------+-----------------+-----------------------------------+------------------------------------------------------------+
| Type | Wager | Typical payout | Actual odds | House edge |
+================+====================================================================================+=================+===================================+============================================================+
| Single Die Bet | A specific number will appear | 1 die matches:\ | \ | {{#expr:100\*(1-2\*75/216-3\*15/216-11\*1/216) round 2}}%\ |
| | | 1 to 1 | ({{#expr:100\*75/216 round 2}}%) | (10:1) |
| | | | | |
| | | | | {{#expr:100\*(1-2\*75/216-3\*15/216-4\*1/216) round 2}}%\ |
| | | | | (3:1) |
+----------------+------------------------------------------------------------------------------------+-----------------+-----------------------------------+------------------------------------------------------------+
| | | 2 dice match:\ | \ | |
| | | 2 to 1 | ({{#expr:100\*15/216 round 2}}%) | |
+----------------+------------------------------------------------------------------------------------+-----------------+-----------------------------------+------------------------------------------------------------+
| | | 3 dice match:\ | \ | |
| | | 10 to 1 | ({{#expr:100\*1/216 round 2}}%) | |
+----------------+------------------------------------------------------------------------------------+-----------------+-----------------------------------+------------------------------------------------------------+
| Any Triple | Any of the triples (all three dice show the same number) will appear | 30 to 1 | \ | {{#expr:100\*(1-31\*6/216) round 2}}% |
| | | | ({{#expr:100\*6/216 round 2}}%) | |
+----------------+------------------------------------------------------------------------------------+-----------------+-----------------------------------+------------------------------------------------------------+
| Big | The total score will be 11 (sometimes 12) or higher with the exception of a triple | 1 to 1 | \ | {{#expr:100\*(1-2\*105/216) round 2}}%\ |
| | | | ({{#expr:100\*105/216 round 2}}%) | (≥11) |
+----------------+------------------------------------------------------------------------------------+-----------------+-----------------------------------+------------------------------------------------------------+
| Small | The total score will be 10 (sometimes 9) or lower with the exception of a triple | 1 to 1 | \ | {{#expr:100\*(1-2\*105/216) round 2}}%\ |
| | | | ({{#expr:100\*105/216 round 2}}%) | (≤10) |
+----------------+------------------------------------------------------------------------------------+-----------------+-----------------------------------+------------------------------------------------------------+
| Field | The total score will be outside the range of 8 to 12 (inclusive) | 1 to 1 | \ | {{#expr:100\*(1-2\*91/216) round 2}}%\ |
| | | | ({{#expr:100\*91/216 round 2}}%) | (\<8 & \>12) |
+----------------+------------------------------------------------------------------------------------+-----------------+-----------------------------------+------------------------------------------------------------+
Notes
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# Chuck-a-luck
## Rules
### House advantage or edge {#house_advantage_or_edge}
Chuck-a-luck is a game of chance. On average, the players are expected to lose more than they win. The casino\'s advantage (house advantage or house edge) is greater than most other casino games and can be much greater for certain wagers. According to John Scarne, \"habitual gamblers stay away from Chuck-a-Luck because they know how little chance they have against such a high \[house edge\]. They call Chuck-a-Luck \'the champ chump\'s game.{{\'\"}}
For the single die bet, there are 216 (6 × 6 × 6) possible outcomes for a throw of three dice. For a specific number:
- there are 75 possible outcomes where only one die will match the number;
- there are 15 possible outcomes where two dice will match; and
- there is one possible outcome where all three dice will match; and so
- there are 125 possible outcomes where no die will match the number.
At payouts of 1 to 1, 2 to 1 and 10 to 1 respectively for each of these types of outcome, the expected loss as a percentage of the stake wagered is:
1 - ((75/216) × 2 + (15/216) × 3 + (1/216) × 11) = 4.6%
At more disadvantageous payouts of 1 to 1, 2 to 1 and 3 to 1, the expected loss as a percentage of the stake wagered is:
1 - ((75/216) × 2 + (15/216) × 3 + (1/216) × 4) = 7.9%
If the payouts are adjusted to 1 to 1, 3 to 1 and 5 to 1 respectively, the expected loss as a percentage is:
1 - ((75/216) × 2 + (15/216) × 4 + (1/216) × 6) = 0%
Commercially organised gambling games almost always have a house advantage which acts as a fee for the privilege of being allowed to play the game, so the last scenario would represent a payout system used for a home game, where players take turns being the role of banker/casino.
## Variants
- As noted previously, the single-die wager of chuck-a-luck is essentially identical to Crown and Anchor, the traditional Vietnamese game *Bau cua ca cop*, and the Chinese dice game Hoo Hey How, each of which use six-sided dice with symbols instead of pips.
- A version of the Big Six wheel is loosely based on chuck-a-luck, with selected combinations of three dice appearing in 54 slots on a spinning wheel. Because of the distribution of the combinations, the house advantage or edge for this wheel is greater than for chuck-a-luck.
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# Chuck-a-luck
## In popular culture {#in_popular_culture}
There is a reference to chuck-a-luck in the Abbott and Costello film *Hold That Ghost*.
In Fritz Lang\'s 1952 film, *Rancho Notorious*, chuck-a-luck is the name of the ranch run by Altar Keane (played by Marlene Dietrich) where outlaws hide from the law. Chuck-a-luck is featured in the lyrics to the theme song and in some plot points.
The game is played by Lazar in the James Bond movie *The Man with the Golden Gun*.
The game is played by Freddie Rumsen in *Mad Men* season 2 episode 9, \"Six-Month Leave\".
In *Dragonfly in Amber* the character Claire Randall describes the activity inside of an inn as having several soldiers playing chuck-a-luck on the floor along with a dog sleeping by the fire and smelling strongly of hops
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# Chipmunk
**Chipmunks** are small, striped rodents of subtribe **Tamiina**. Chipmunks are found in North America, with the exception of the Siberian chipmunk which is found primarily in Asia.
## Taxonomy and systematics {#taxonomy_and_systematics}
Chipmunks are classified as four genera: *Tamias*, of which the eastern chipmunk (*T. striatus*) is the only living member; *Eutamias*, of which the Siberian chipmunk (*E. sibiricus*) is the only living member; *Nototamias*, which consists of three extinct species, and *Neotamias*, which includes the 23 remaining, mostly western North American, species. These classifications were treated as subgenera due to the chipmunks\' morphological similarities. As a result, most taxonomies over the twentieth century have placed the chipmunks into a single genus. Joseph C. Moore reclassified chipmunks to form a subtribe Tamiina in a 1959 study, and this classification has been supported by studies of mitochondrial DNA.
The common name originally may have been spelled \"chitmunk\", from the native Odawa (Ottawa) word *jidmoonh*, meaning \"red squirrel\" (*cf.* Ojibwe *ᐊᒋᑕᒨ* *ajidamoo*). The earliest form cited in the *Oxford English Dictionary* is \"chipmonk\", from 1842. Other early forms include \"chipmuck\" and \"chipminck\", and in the 1830s they were also referred to as \"chip squirrels\", probably in reference to the sound they make. In the mid-19th century, John James Audubon and his sons included a lithograph of the chipmunk in their *Viviparous Quadrupeds of North America*, calling it the \"chipping squirrel \[or\] hackee\". Chipmunks have also been referred to as \"ground squirrels\" (although the name \"ground squirrel\" may refer to other squirrels, such as those of the genus *Spermophilus*).
## Diet
Chipmunks have an omnivorous diet primarily consisting of seeds, nuts and other fruits, and buds. They also commonly eat grass, shoots, and many other forms of plant matter, as well as fungi, insects and other arthropods, small frogs, worms, and bird eggs. They will also occasionally eat newly hatched baby birds. Around humans, chipmunks can eat cultivated grains and vegetables, and other plants from farms and gardens, so they are sometimes considered pests. Chipmunks mostly forage on the ground, but they climb trees to obtain nuts such as hazelnuts and acorns. At the beginning of autumn, many species of chipmunk begin to stockpile nonperishable foods for winter. They mostly cache their foods in a larder in their burrows and remain in their nests until spring, unlike some other species which make multiple small caches of food. Cheek pouches allow chipmunks to carry food items to their burrows for either storage or consumption.
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# Chipmunk
## Ecology and life history {#ecology_and_life_history}
Eastern chipmunks, the largest of the chipmunks, mate in early spring and again in early summer, producing litters of four or five young twice each year. Western chipmunks breed only once a year. The young emerge from the burrow after about six weeks and strike out on their own within the next two weeks.
These small mammals fulfill several important functions in forest ecosystems. Their activities harvesting and hoarding tree seeds play a crucial role in seedling establishment. They consume many different kinds of fungi, including those involved in symbiotic mycorrhizal associations with trees, and are a vector for dispersal of the spores of subterranean sporocarps (truffles) in some regions.
Chipmunks construct extensive burrows which can be more than 3.5 m in length with several well-concealed entrances. The sleeping quarters are kept clear of shells, and feces are stored in refuse tunnels.
The eastern chipmunk hibernates in the winter, while western chipmunks do not, relying on the stores in their burrows.
Chipmunks play an important role as prey for various predatory mammals and birds but are also opportunistic predators themselves, particularly with regard to bird eggs and nestlings, as in the case of eastern chipmunks and mountain bluebirds (*Siala currucoides*).
Chipmunks typically live about three years, although some have been observed living to nine years in captivity.
Chipmunks are diurnal. In captivity, they are said to sleep for an average of about 15 hours a day. It is thought that mammals which can sleep in hiding, such as rodents and bats, tend to sleep longer than those that must remain on alert
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# Computer music
**Computer music** is the application of computing technology in music composition, to help human composers create new music or to have computers independently create music, such as with algorithmic composition programs. It includes the theory and application of new and existing computer software technologies and basic aspects of music, such as sound synthesis, digital signal processing, sound design, sonic diffusion, acoustics, electrical engineering, and psychoacoustics. The field of computer music can trace its roots back to the origins of electronic music, and the first experiments and innovations with electronic instruments at the turn of the 20th century.
## History
Much of the work on computer music has drawn on the relationship between music and mathematics, a relationship that has been noted since the Ancient Greeks described the \"harmony of the spheres\".
Musical melodies were first generated by the computer originally named the CSIR Mark 1 (later renamed CSIRAC) in Australia in 1950. There were newspaper reports from America and England (early and recently) that computers may have played music earlier, but thorough research has debunked these stories as there is no evidence to support the newspaper reports (some of which were speculative). Research has shown that people *speculated* about computers playing music, possibly because computers would make noises, but there is no evidence that they did it.
The world\'s first computer to play music was the CSIR Mark 1 (later named CSIRAC), which was designed and built by Trevor Pearcey and Maston Beard in the late 1940s. Mathematician Geoff Hill programmed the CSIR Mark 1 to play popular musical melodies from the very early 1950s. In 1950 the CSIR Mark 1 was used to play music, the first known use of a digital computer for that purpose. The music was never recorded, but it has been accurately reconstructed. In 1951 it publicly played the \"Colonel Bogey March\" of which only the reconstruction exists. However, the CSIR Mark 1 played standard repertoire and was not used to extend musical thinking or composition practice, as Max Mathews did, which is current computer-music practice.
The first music to be performed in England was a performance of the British National Anthem that was programmed by Christopher Strachey on the Ferranti Mark 1, late in 1951. Later that year, short extracts of three pieces were recorded there by a BBC outside broadcasting unit: the National Anthem, \"Baa, Baa, Black Sheep\", and \"In the Mood\"; this is recognized as the earliest recording of a computer to play music as the CSIRAC music was never recorded. This recording can be heard at the Manchester University site. Researchers at the University of Canterbury, Christchurch declicked and restored this recording in 2016 and the results may be heard on SoundCloud.
Two further major 1950s developments were the origins of digital sound synthesis by computer, and of algorithmic composition programs beyond rote playback. Amongst other pioneers, the musical chemists Lejaren Hiller and Leonard Isaacson worked on a series of algorithmic composition experiments from 1956 to 1959, manifested in the 1957 premiere of the *Illiac Suite* for string quartet. Max Mathews at Bell Laboratories developed the influential MUSIC I program and its descendants, further popularising computer music through a 1963 article in *Science*. The first professional composer to work with digital synthesis was James Tenney, who created a series of digitally synthesized and/or algorithmically composed pieces at Bell Labs using Mathews\' MUSIC III system, beginning with *Analog #1 (Noise Study)* (1961). After Tenney left Bell Labs in 1964, he was replaced by composer Jean-Claude Risset, who conducted research on the synthesis of instrumental timbres and composed *Computer Suite from Little Boy* (1968).
Early computer-music programs typically did not run in real time, although the first experiments on CSIRAC and the Ferranti Mark 1 did operate in real time. From the late 1950s, with increasingly sophisticated programming, programs would run for hours or days, on multi million-dollar computers, to generate a few minutes of music. One way around this was to use a \'hybrid system\' of digital control of an analog synthesiser and early examples of this were Max Mathews\' GROOVE system (1969) and also MUSYS by Peter Zinovieff (1969).
Until now partial use has been exploited for musical research into the substance and form of sound (convincing examples are those of Hiller and Isaacson in Urbana, Illinois, US; Iannis Xenakis in Paris and Pietro Grossi in Florence, Italy).
In May 1967 the first experiments in computer music in Italy were carried out by the *S 2F M studio* in Florence in collaboration with *General Electric Information Systems* Italy. *Olivetti-General Electric GE 115* (Olivetti S.p.A.) is used by Grossi as a *performer*: three programmes were prepared for these experiments. The programmes were written by Ferruccio Zulian and used by Pietro Grossi for playing Bach, Paganini, and Webern works and for studying new sound structures.
John Chowning\'s work on FM synthesis from the 1960s to the 1970s allowed much more efficient digital synthesis, eventually leading to the development of the affordable FM synthesis-based Yamaha DX7 digital synthesizer, released in 1983.
> Interesting sounds must have a fluidity and changeability that allows them to remain fresh to the ear. In computer music this subtle ingredient is bought at a high computational cost, both in terms of the number of items requiring detail in a score and in the amount of interpretive work the instruments must produce to realize this detail in sound.
### In Japan {#in_japan}
In Japan, experiments in computer music date back to 1962, when Keio University professor Sekine and Toshiba engineer Hayashi experimented with the TOSBAC computer. This resulted in a piece entitled *TOSBAC Suite*, influenced by the *Illiac Suite*. Later Japanese computer music compositions include a piece by Kenjiro Ezaki presented during Osaka Expo \'70 and \"Panoramic Sonore\" (1974) by music critic Akimichi Takeda. Ezaki also published an article called \"Contemporary Music and Computers\" in 1970. Since then, Japanese research in computer music has largely been carried out for commercial purposes in popular music, though some of the more serious Japanese musicians used large computer systems such as the *Fairlight* in the 1970s.
In the late 1970s these systems became commercialized, including systems like the Roland MC-8 Microcomposer, where a microprocessor-based system controls an analog synthesizer, released in 1978. In addition to the Yamaha DX7, the advent of inexpensive digital chips and microcomputers opened the door to real-time generation of computer music. In the 1980s, Japanese personal computers such as the NEC PC-88 came installed with FM synthesis sound chips and featured audio programming languages such as Music Macro Language (MML) and MIDI interfaces, which were most often used to produce video game music, or chiptunes. By the early 1990s, the performance of microprocessor-based computers reached the point that real-time generation of computer music using more general programs and algorithms became possible.
## Advances
Advances in computing power and software for manipulation of digital media have dramatically affected the way computer music is generated and performed. Current-generation micro-computers are powerful enough to perform very sophisticated audio synthesis using a wide variety of algorithms and approaches. Computer music systems and approaches are now ubiquitous, and so firmly embedded in the process of creating music that we hardly give them a second thought: computer-based synthesizers, digital mixers, and effects units have become so commonplace that use of digital rather than analog technology to create and record music is the norm, rather than the exception.
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# Computer music
## Research
There is considerable activity in the field of computer music as researchers continue to pursue new and interesting computer-based synthesis, composition, and performance approaches. Throughout the world there are many organizations and institutions dedicated to the area of computer and electronic music study and research, including the CCRMA (Center of Computer Research in Music and Acoustic, Stanford, USA), ICMA (International Computer Music Association), C4DM (Centre for Digital Music), IRCAM, GRAME, SEAMUS (Society for Electro Acoustic Music in the United States), CEC (Canadian Electroacoustic Community), and a great number of institutions of higher learning around the world.
### Music composed and performed by computers {#music_composed_and_performed_by_computers}
Later, composers such as Gottfried Michael Koenig and Iannis Xenakis had computers generate the sounds of the composition as well as the score. Koenig produced algorithmic composition programs which were a generalization of his own serial composition practice. This is not exactly similar to Xenakis\' work as he used mathematical abstractions and examined how far he could explore these musically. Koenig\'s software translated the calculation of mathematical equations into codes which represented musical notation. This could be converted into musical notation by hand and then performed by human players. His programs Project 1 and Project 2 are examples of this kind of software. Later, he extended the same kind of principles into the realm of synthesis, enabling the computer to produce the sound directly. SSP is an example of a program which performs this kind of function. All of these programs were produced by Koenig at the Institute of Sonology in Utrecht in the 1970s. In the 2000s, Andranik Tangian developed a computer algorithm to determine the time event structures for rhythmic canons and rhythmic fugues, which were then \"manually\" worked out into harmonic compositions *Eine kleine Mathmusik I* and *Eine kleine Mathmusik II* performed by computer; for scores and recordings see.
### Computer-generated scores for performance by human players {#computer_generated_scores_for_performance_by_human_players}
Computers have also been used in an attempt to imitate the music of great composers of the past, such as Mozart. A present exponent of this technique is David Cope, whose computer programs analyses works of other composers to produce new works in a similar style. Cope\'s best-known program is Emily Howell.
Melomics, a research project from the University of Málaga (Spain), developed a computer composition cluster named Iamus, which composes complex, multi-instrument pieces for editing and performance. Since its inception, Iamus has composed a full album in 2012, also named *Iamus*, which *New Scientist* described as \"the first major work composed by a computer and performed by a full orchestra\". The group has also developed an API for developers to utilize the technology, and makes its music available on its website.
### `{{anchor|Computer-Aided Algorithmic Composition}}`{=mediawiki}Computer-aided algorithmic composition {#computer_aided_algorithmic_composition}
Computer-aided algorithmic composition (CAAC, pronounced \"sea-ack\") is the implementation and use of algorithmic composition techniques in software. This label is derived from the combination of two labels, each too vague for continued use. The label *computer-aided composition* lacks the specificity of using generative algorithms. Music produced with notation or sequencing software could easily be considered computer-aided composition. The label *algorithmic composition* is likewise too broad, particularly in that it does not specify the use of a computer. The term computer-aided, rather than computer-assisted, is used in the same manner as computer-aided design.
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# Computer music
## Machine improvisation {#machine_improvisation}
Machine improvisation uses computer algorithms to create improvisation on existing music materials. This is usually done by sophisticated recombination of musical phrases extracted from existing music, either live or pre-recorded. In order to achieve credible improvisation in particular style, machine improvisation uses machine learning and pattern matching algorithms to analyze existing musical examples. The resulting patterns are then used to create new variations \"in the style\" of the original music, developing a notion of stylistic re-injection. This is different from other improvisation methods with computers that use algorithmic composition to generate new music without performing analysis of existing music examples.
### Statistical style modeling {#statistical_style_modeling}
Style modeling implies building a computational representation of the musical surface that captures important stylistic features from data. Statistical approaches are used to capture the redundancies in terms of pattern dictionaries or repetitions, which are later recombined to generate new musical data. Style mixing can be realized by analysis of a database containing multiple musical examples in different styles. Machine Improvisation builds upon a long musical tradition of statistical modeling that began with Hiller and Isaacson\'s *Illiac Suite for String Quartet* (1957) and Xenakis\' uses of Markov chains and stochastic processes. Modern methods include the use of lossless data compression for incremental parsing, prediction suffix tree, string searching and more. Style mixing is possible by blending models derived from several musical sources, with the first style mixing done by S. Dubnov in a piece NTrope Suite using Jensen-Shannon joint source model. Later the use of factor oracle algorithm (basically a *factor oracle* is a finite state automaton constructed in linear time and space in an incremental fashion) was adopted for music by Assayag and Dubnov and became the basis for several systems that use stylistic re-injection.
### Implementations
The first implementation of statistical style modeling was the LZify method in Open Music, followed by the Continuator system that implemented interactive machine improvisation that interpreted the LZ incremental parsing in terms of Markov models and used it for real time style modeling developed by François Pachet at Sony CSL Paris in 2002. Matlab implementation of the Factor Oracle machine improvisation can be found as part of Computer Audition toolbox. There is also an NTCC implementation of the Factor Oracle machine improvisation.
OMax is a software environment developed in IRCAM. OMax uses OpenMusic and Max. It is based on researches on stylistic modeling carried out by Gerard Assayag and Shlomo Dubnov and on researches on improvisation with the computer by G. Assayag, M. Chemillier and G. Bloch (a.k.a. the *OMax Brothers*) in the Ircam Music Representations group. One of the problems in modeling audio signals with factor oracle is the symbolization of features from continuous values to a discrete alphabet. This problem was solved in the Variable Markov Oracle (VMO) available as python implementation, using an information rate criteria for finding the optimal or most informative representation.
### Use of artificial intelligence {#use_of_artificial_intelligence}
The use of artificial intelligence to generate new melodies, cover pre-existing music, and clone artists\' voices, is a recent phenomenon that has been reported to disrupt the music industry.
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# Computer music
## Live coding {#live_coding}
Live coding (sometimes known as \'interactive programming\', \'on-the-fly programming\', \'just in time programming\') is the name given to the process of writing software in real time as part of a performance. Recently it has been explored as a more rigorous alternative to laptop musicians who, live coders often feel, lack the charisma and pizzazz of musicians performing live
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# Concept
A **concept** is an abstract idea that serves as a foundation for more concrete principles, thoughts, and beliefs. Concepts play an important role in all aspects of cognition. As such, concepts are studied within such disciplines as linguistics, psychology, and philosophy, and these disciplines are interested in the logical and psychological structure of concepts, and how they are put together to form thoughts and sentences. The study of concepts has served as an important flagship of an emerging interdisciplinary approach, cognitive science.
In contemporary philosophy, three understandings of a concept prevail:
- mental representations, such that a concept is an entity that exists in the mind (a mental object)
- abilities peculiar to cognitive agents (mental states)
- Fregean senses, abstract objects rather than a mental object or a mental state
Concepts are classified into a hierarchy, higher levels of which are termed \"superordinate\" and lower levels termed \"subordinate\". Additionally, there is the \"basic\" or \"middle\" level at which people will most readily categorize a concept. For example, a basic-level concept would be \"chair\", with its superordinate, \"furniture\", and its subordinate, \"easy chair\".
Concepts may be exact or inexact. When the mind makes a generalization such as the concept of *tree*, it extracts similarities from numerous examples; the simplification enables higher-level thinking. A concept is instantiated (reified) by all of its actual or potential instances, whether these are things in the real world or other ideas.
Concepts are studied as components of human cognition in the cognitive science disciplines of linguistics, psychology, and philosophy, where an ongoing debate asks whether all cognition must occur through concepts. Concepts are regularly formalized in mathematics, computer science, databases and artificial intelligence. Examples of specific high-level conceptual classes in these fields include classes, schema or categories. In informal use, the word *concept* can refer to any idea.
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# Concept
## Ontology of concepts {#ontology_of_concepts}
A central question in the study of concepts is the question of what they *are*. Philosophers construe this question as one about the ontology of concepts---what kind of things they are. The ontology of concepts determines the answer to other questions, such as how to integrate concepts into a wider theory of the mind, what functions are allowed or disallowed by a concept\'s ontology, etc. There are two main views of the ontology of concepts: (1) Concepts are abstract objects, and (2) concepts are mental representations.
### Concepts as mental representations {#concepts_as_mental_representations}
#### The psychological view of concepts {#the_psychological_view_of_concepts}
Within the framework of the representational theory of mind, the structural position of concepts can be understood as follows: Concepts serve as the building blocks of what are called *mental representations* (colloquially understood as *ideas in the mind*). Mental representations, in turn, are the building blocks of what are called *propositional attitudes* (colloquially understood as the stances or perspectives we take towards ideas, be it \"believing\", \"doubting\", \"wondering\", \"accepting\", etc.). And these propositional attitudes, in turn, are the building blocks of our understanding of thoughts that populate everyday life, as well as folk psychology. In this way, we have an analysis that ties our common everyday understanding of thoughts down to the scientific and philosophical understanding of concepts.
#### The physicalist view of concepts {#the_physicalist_view_of_concepts}
In a physicalist theory of mind, a concept is a mental representation, which the brain uses to denote a class of things in the world. This is to say that it is literally a symbol or group of symbols together made from the physical material of the brain. Concepts are mental representations that allow us to draw appropriate inferences about the type of entities we encounter in our everyday lives. Concepts do not encompass all mental representations, but are merely a subset of them. The use of concepts is necessary to cognitive processes such as categorization, memory, decision making, learning, and inference.
Concepts are thought to be stored in long term cortical memory, in contrast to episodic memory of the particular objects and events which they abstract, which are stored in hippocampus. Evidence for this separation comes from hippocampal damaged patients such as patient HM. The abstraction from the day\'s hippocampal events and objects into cortical concepts is often considered to be the computation underlying (some stages of) sleep and dreaming. Many people (beginning with Aristotle) report memories of dreams which appear to mix the day\'s events with analogous or related historical concepts and memories, and suggest that they were being sorted or organized into more abstract concepts. (\"Sort\" is itself another word for concept, and \"sorting\" thus means to organize into concepts.)
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