text:
Talk:List of English words of Russian origin

Words to delete
Some of these words already have equivalents in english language

Cosmonaut = Astronaut
 * They have difference in meaning that identifies origin of a person. Cosmonaut is from USSR/Russia, astronaut is from US or Europe, Taikonaut is from China. 195.211.195.185 (talk) 11:20, 23 December 20uyitreioyfa HOME

PLANNER VIRTUAL LIBRARY MORE Today Wed, November 29 My Courses Links Announcements Be sure to attend an fun-filled field trip on our Statewide Event Day, Dec. 7th! Click on the Message Boards to find more information about a field trip near you! Events*the time below reflects PST Time*	Schedule	Schedule Type 10:30 AM - 11:00 AM	*Optional*Env Sci OpenM.13 (UTC) Knout = Cat o' nine tails

Dvoryanstvo = Nobility

Spetsnaz = Special forces

Stavka = Staff (military)

Katorga = imprisonment with (hard?) labour (not sure if that's the correct legal term)

Ukase = decree

Elektrichka = electric-powered train

Banya = saunadrsa

Burlak = bfddf arge-puller

Dacha = summerhouse

Mat = profanity

Zek = a convicterh oiytr2e7((((((((((((((((((((((((((((((((((((((((((((((>_<>>_<>>_<>>_<>>_<>>_<>>_<>>_<>>_<>>_<>>_<>>_<>>_<>>_<>>_<>>_<>>_<>>_<>>_<>>_<>>_<>>_<>

Propiska = registered place of residence?

Rasputitsa = mud season — Preceding unsigned comment added by Rheinguld (talk • contribs) 09:02, 29 September 2012 (UTC) --- "Sbitenshchik" is a derivative of a word "Sbiten"

"Pavlova" can't be considered a loanword because it's derived from a personal name.

"Commissar" is obviously a french word and there were commissars in tsarist times (although I don't remember what their purpose was).

"Tsar" is a church slavonic word.

Don't know how did "preved", "padonki" and "chainik" get into this list.

Rheinguld 12:43, 21 Sep 2012 (UTC)

Kpalion's suggestion
I suggest merging this list and List of English words of Polish origin into one new article List of English words of Slavic origin. The two lists have too much in common and I fear a war about "is this or that word Polish or Russian?" whan they're in fact Slavic. Kpalion 22:43, 25 Mar 2004 (UTC)

 * It is also to be noted that a huge part of the words mentioned here on this page are of Turkic origin, not russian. Out of the first set these are: balaclava, balalaika, Kazakh, steppe, kephir (kefir), kumis (kumys), kurgan... [[User:Halibutt|Halibutt]] 03:02, Oct 11, 2004 (UTC)
 * Balaclava and some of the other examples you mention are russified Turkic words, but they were already russified when they had gotten into the English language. The context really matters. I'm adding Balaclava (back?) to the list with the note that it's a russified originally Tatar name.24.6.239.183 (talk) 04:49, 17 November 2013 (UTC)

'Taiga' is also Turkic, according to my reference, as is 'mammoth' (from Tartar). 'Tundra' is not Slavic either, but from Sami. No way can this list be merged with a "Slavic" list. Alexander 007 03:24, 16 Feb 2005 (UTC)
 * I agree that no merging should take place. As someone who has read every list in the list of Lists of etymologies (and done in-depth research on about a third of them), I can tell you that there is much repitition, some out of sloppiness, and some out of careful consideration of conflicting theories.  I think the best solution is to note these conflicting theories next to the word in question in all places that it appears (briefly of course) and provide a link(s) to the list in which that word also appears or to that word/concept's specific page (i.e. at mammoth) where the etymology can be treated in depth in one place.  This way, someone truly interested in the matter can easily investigate it through links and novices can be aware of conflicting theories without being overwhelmed by an etymological flood.--Hraefen 00:54, 15 November 2005 (UTC)
 * The Oxford English Dictionary says that mammoth is Russian, (from "mamant" - The bones which were found in Russia before Europe took an interest.)
 * 'Mammoth' is a russified Yakut word (not Tatar).24.6.239.183 (talk) 04:49, 17 November 2013 (UTC)

Bistro
Someone removed Bistro from the list. As a matter of fact that word is indeed of Russian origin, although it might've came to English from French. Halibutt 07:28, Apr 11, 2005 (UTC)

 * Perhaps it is, but I couldn't find any evidence of that in the Oxford English Dictionary, the Oxford American Dictionary, the American Heritage Dictionary, or the Merriam-Webster Dictionary. All of them list French as the only etymological source. I'd be glad to have it back if you can show any evidence that the word came to French from Russian. It's quite possible that it is in fact Russian; I just couldn't find any evidence in the usual areas of etymological inquiry. Nohat 07:22, 21 July 2005 (UTC)

You have looked not very carefully.

Word History: According to a popular story, bistro came into existence as a French word when Russian soldiers entered Parisian restaurants and cafés after the fall of Napoleon in 1815 shouting “bystro, bystro,” Russian for “quickly, quickly.” Bistros seem to have been named not for this desire for quick service but possibly for a commodity to be found in at least some of them, since the French word bistro may be related to the word bistouille,“raw spirits, rotgut.” Another possibility is that the word bistro comes from the dialectal word bistraud,“young cowherd.” In Standard French the term may have come to mean “wine merchant's helper” and then “an establishment selling wine.” Although the French word bistro is first recorded in 1884, evidence for the English word bistro is not found until the early 1920's.

''Excerpted from The American Heritage Dictionary of the English Language, Third Edition Copyright © 1992 by Houghton Mifflin Company. Electronic version licensed from Lernout & Hauspie Speech Products N.V., further reproduction and distribution restricted in accordance with the Copyright Law of the United States. All rights reserved.''

Attempts of AHD to debunk a "popular story" don't look convincing. (1) That somemone was looking for raw spirits (i.e., moonshine) in a restaurant is laughable idea. (2) "young cowherd" for "merchant's server" is so pitiful. And all reeks of what is called folk etymology, not much better than the Cossacks history. mikka (t) 15:34, 21 July 2005 (UTC)

Not to say taht removing someone's adition is an improper approach. You should have raised your doubts on the talk page first. And the best authority here is a French dictionary, not English. Parlez-vous...? mikka (t) 15:36, 21 July 2005 (UTC)

 * None of the 3 major English dictionaries with etymologies sanction the Russian origin of bistro, and this discussion from a 13-year-old edition of AHD acknowledges the story, but rejects it. Where are the etymological sources supporting the "popular story" theory that justify putting "bistro" back? Nohat 16:28, 21 July 2005 (UTC)

Kasha

 * From Merriam-Webster Dictionary: "Etymology: Russian"
 * From American Heritage Dictionary: "Russian, from Old Russian"
 * From Oxford English Dictionary: "Kasha... [Russ.]" (no URL available.) See OED, 2nd ed. Nohat 06:38, 21 July 2005 (UTC)

 * Generic Slavic word, used in most Western and Eastern Slavic languages. What makes it a Russian word? Especially that it was in use at least since 10th century, that is long before Russian came to life? Halibutt 21:54, July 21, 2005 (UTC)

 * It may be that this word is shared among many Slavic languages, but the evidence available to the lexicographers at these major dictionaries indicates that the English word kasha was borrowed from Russian and not from any other Slavic language. If the evidence were unclear, then the etymology would say so. Nohat 07:11, 22 July 2005 (UTC)

Smetana

 * From Oxford English Dictionary: "[a. Russ. smetána sour cream, f. smetat´ to sweep together, collect.] ", (no URL available.) see OED, 2nd ed.
 * AHD and M-W only have biographical entries for Smetana, not the sour cream sense. Nohat 06:38, 21 July 2005 (UTC)

 * No wonder, after all it's a common noun in all Western Slavic languages, from where it was imported to Russian. Halibutt 21:53, July 21, 2005 (UTC)

Balalaika

 * Nohat 06:47, 21 July 2005 (UTC)

Cosmonaut

 * Nohat 06:47, 21 July 2005 (UTC)

 * Comes from Greek cosmos and nauta, or traveller. Hardly a Russian origin, though it is mostly used to denote astronauts from the eastern bloc. Halibutt 21:39, July 21, 2005 (UTC)

Intelligentsia

 * Nohat 06:47, 21 July 2005 (UTC)

 * Check the article on intelligentsia. There are proofs of the Polish origin of the term. Halibutt 21:40, July 21, 2005 (UTC)

Intelligentsia is a Russian Word
This is a Russian word meaning Intelligence. It is no way of Polish origin. Balalaika is a instrument invented by the Russian People. Cosmonaut is also Russian. Same as Kazakh which is a person living in Kazakhstan, or their language which has a lot of Russian words. Steppe, Taiga, and Tundra, are also Russian words. Shashlik and Mammoth are Russian words. Rusf (talk) 16:03, 8 July 2010 (UTC)

Kazakh

 * Nohat 06:47, 21 July 2005 (UTC)
 * Didn't you mean Cossack? Bronx 20:07, 28 December 2006 (UTC)

Steppe

 * Nohat 06:47, 21 July 2005 (UTC)

 * From Ukrainian step, which in turn came from Old Ruthenian. Halibutt 21:47, July 21, 2005 (UTC)

Taiga

 * Nohat 06:47, 21 July 2005 (UTC)

 * From either Yakut or Mongolian. Halibutt 21:44, July 21, 2005 (UTC)

Shashlik

 * Nohat 06:47, 21 July 2005 (UTC)

 * From Turkic sis or shish, meaning a poker or a broach; see sheesh-kebab for comparison. Unless of course kebab is also of Russian origin... Halibutt 21:45, July 21, 2005 (UTC)

Chernozem

 * Nohat 06:47, 21 July 2005 (UTC)

 * Might as well be of any other Slavic language, with Ukrainian being the most probable, but I'm not 100% sure on this one. Halibutt 21:46, July 21, 2005 (UTC)

 * If the etymological scholars that write the major respected English dictionaries say a word has Russian origin, it seems much more likely that they are right than some Wikipedian's unsourced theories. Show some legitimate etymological evidence that these words did not pass into English via Russian. Also, it is possible for words to have multiple origins; that is, a word that came to English ultimately OR proximately from that language, or anywhere in between. These "List of words of X origin" pages are not limited to words that are only ultimately from X language, but to any language through which the word passed on its way to English. Note, however, that "any language through which the word passed on its way to English" does not mean any language that also borrowed a word from the same language English did. Nohat 07:07, 22 July 2005 (UTC)

 * This one was introduced in English by translator of Vasily V. Dokuchaev's classic study Chernozem. --Ghirlandajo 12:06, 8 August 2005 (UTC)

Mammoth
(Pasted from above:) '''Taiga' is also Turkic, according to my reference, as is 'mammoth' (from Tartar). 'Tundra' is not Slavic either, but from Sami. No way can this list be merged with a "Slavic" list. Alexander 007 03:24, 16 Feb 2005 (UTC)''
 * The Oxford English Dictionary says that mammoth is Russian, (from "mamant" - The bones which were found in Russia before Europe took an interest.) User:Sonic Mew | talk to me 10:14, 17 Oct 2005 (UTC)

 * My dear Sonic Mew, your link says that English mammoth is from "an Old Russian word mamant"---yes it is, but apparently it didn't occur to you that this Old Russian word may not be native Slavonic, but in fact from a Turkic language? My AHD gives the etymology of English mammoth like this:

 * "[Obsolete Russian mammot' , from Tartar mamont, "earth"]"

 * ---Is the AHD wrong? I'll let someone else research this, since I can't be bothered. Alexander 007 17:59, 8 December 2005 (UTC)
 * No, it is not wrong. We are speaking about words that came into English from Russian. The intro clearly says that many of them originated elsewhere. In some cases the "original origin" is indicated. mikka (t) 19:01, 8 December 2005 (UTC)

 * No, you misunderstand my dispute. I do not question that mammoth entered English from Russian. My dispute is that the Russian word may in turn be from Tatar, thus not a word of Slavic origin, so Kpalion's suggestion of moving the list to "List of English words of Slavic origin" was not a good idea (I was never suggesting removing the word mammoth from the List, I was objecting to merging with a List of English words of Slavic origin). The AHD simply states that mammoth is from Russian, and the Russian word is from Tatar. Alexander 007 19:04, 8 December 2005 (UTC)
 * also I have a feeling that Sonic Mew is under the impression that his Oxford link somehow proves that mamant is a native Russian word (hence, a Slavic word), when in fact it is probably a loan from Tatar. Alexander 007 19:44, 8 December 2005 (UTC)

cuisine
surely the latest additions are not Russian words in current use in the English language? Not in the same general peoples awareness like "samovar"GraemeLeggett 17:43, 8 December 2005 (UTC)

 * I'm also very suspicious of the latest additions. Such words are only known to people familiar with Russian cuisine, not in the general English language or in general English dictionaries AFAIK. The edits should be reverted. Alexander 007 17:46, 8 December 2005 (UTC)
 * We have articles in wikipedia. I find this fact on par with "general English dictionaries" (this was the goal of the wikipedia project AFAIK).
 * Also, the article says: Most of them are used to denote things and notions specific to Russia, Russian culture, politics, history. mikka (t) 19:01, 8 December 2005 (UTC)

 * Well, that seems ok. But most English-speakers have no idea what those words refer to, nor will you find them in most English dictionaries. Alexander 007 19:06, 8 December 2005 (UTC)

 * Borscht - This is Ukrainean, I believe, but it seems to have come into English via Russian. 136.36.180.215 (talk) 13:49, 30 May 2024 (UTC)

Yiddish
Should we perhaps mention somewhere that a lot of Russian words came into English through Yiddish? Especially in American English. Dan Carkner 23:08, 13 December 2005 (UTC)

 * Yes, we should. Alexander 007 23:15, 13 December 2005 (UTC)

Capitalized
I have capitalized each word as per the general convention in a dictionary entry. --Bhadani 13:13, 14 March 2006 (UTC)

Parka?
I noticed that "parka" is credited in both this article and the List_of_English_words_of_Native_American_origin. The information on Wikipedia seems to support North American more than Russian, but I don't know that much about it.--Kento 03:13, 12 October 2006 (UTC)

Mammoth
How it is Russian borrowing as in Russian it is "mamont"?--Dojarca 20:28, 30 July 2007 (UTC)
 * See corruption (linguistics). `'Míkka 01:23, 31 July 2007 (UTC)

Loved this page, was a great help!!!
I do like this Wikipedia page, loved the words! I am currently studying for a spelling bee and need extra sources, especially on studying languages. It was a pretty good source!!! I have not seen so many spellings of tsar, though. The only variant I have seen is tzar. Why are there so many variants to the Russian spellings? I am wondering why you list some of which spelling lists from anywhere else wouldn't use...

15zhongk (talk) 01:37, 11 February 2008 (UTC)

 * In the case of the word tsar, the reason is actually pretty basic in this case, essentially the similarity between the sound of "s" and "z". Good dictionaries will list at least the three most common variations, czar, tsar, and tzar. All technically are correct spellings of the word.  In the United States, however, only the spelling "czar" is used when describing someone in contemporary times who has a position of leadership or power, especially in a government agency, e.g. "The Nation's drug czar." When the word is used in a  historical sense, I have noticed the spellings tsar and czar used the most, with tzar used less frequently, and zar rarely.

 * Remember the Russian words are from the Cyrillic alphabet, so the Russian words you see in are transliterations into English of the Russian word. A few of these Russian words may have their own variant spellings, and the transliteration reflects this, or it can be just the transliteration variations itself.   --WordsExpert (talk) 21:27, 9 March 2008 (UTC)

tzar, tsar, czar, zar. Explanation
Czar is the right way to say it in English. Tzar is the right way to say it in Russian. Tsar and zar are just made up. There is no such word as czar in Russian. If you really translate the meaning a Tzar is a King a Tzarstvo (Russian Word) is a Kingdom. A Tzaritza (Russian Word) is a Queen but unfortunately in English King and Queen are both konwn as a Czar. Rusf (talk) 16:01, 8 July 2010 (UTC)

Laika
isn't an English word, she was a dog. Nor are Belomorkanal or the official names of government departments, space programmes etc. Can anyone provide dictionary citations for these? or for 'preved'? Koromislo1 (talk) 17:41, 13 February 2009 (UTC)
 * Second that. The list needs a thorough cleanup of personal, geographic names, trademarks etc. And a special attention to Yiddish, Turkic and common Slavic roots that are not exclusively Russian. NVO (talk) 17:59, 30 March 2009 (UTC)
 * Ha, four years later and it's not done! I just noticed it and wanted to see what others thought ;) Malick78 (talk) 22:17, 10 August 2013 (UTC)

Vodka
Vodka is not diminutuve for water, diminutive for water is 'vodichka'. Vodka refers to a chemical term of 19th century describing a substance diluted with water. From then on it became associated with diluted ethanol. —Preceding unsigned comment added by 74.71.106.171 (talk) 23:26, 21 May 2009 (UTC)
 * Wasn't it actually go from Polish to Russian and then English? Perhaps the dimunitive aspect is from Polish.  — Æµ§œš¹  [aɪm ˈfɻɛ̃ⁿdˡi]  23:49, 21 May 2009 (UTC)

Topor axe
The article states that the first word borrowed into English from Russian was "topor axe", mentioned in the Anglo-Saxon chronicles.

However, the passage in question is about King Canute the Great, who was half Polish, the grandson of King Mieszko, and the nephew of King Boleslaw. It is much more likely that the word is from Polish, then, than it is from Russian.

No source is given supporting the claim that the word is actually Russian. Removed the passage sentence as unsourced.

Second problem was "tschotshcke", which, as the article correctly states is from Yiddish, and originally from Polish. Why would it then be considered as borrowed from Russian? Removed the passage as self-contradictory. —Preceding unsigned comment added by Dominus Vobisdu (talk • contribs) 14:04, 12 January 2010 (UTC)

Everything is right in this page
All the words in this list are from Russian origin. Remember: Russian Language is a part of Slavic Languages. So almost all the words in other Slavic languages are in some close form in Russian and words that are in Russian language are in some form close to Slavic Languages. Slavic is not a language it is just a group of similar languages like Russian (The one with the most speakers), Ukrainian, Belorussian, Bulgarian, etc. Ukrainian is very closely related to Russian even Russian and Ukrainian people understand each other without any problems. Just minor words are different, mostly it is just different pronunciations of vowels. Even the alphabet is the almost the same 1-3 letters are different (I don't remember all the way). Polish came from Russian and Slavic mostly. So a lot of words in Polish are also in Russian. Topor is a Russian word meaning ax. the Anglo-Saxons borrowed it from the Russians a long time ago during their trade for some years until one of the Russian's rulers died. A lot of the words mentioned in these discussion are from Russian. Russian has more ways to pronounce words than English or almost any other languages, except Slavic languages because they are the same in many ways including this one. You can call a car Mashina, Mashinka, Mashinochka. In English you can only call a car a car. There are many words in Russian that other languages don't even have, like premydrost, mydrost is wisdom, premydrost is higher class of wisdom. Other languages don't even have words like that. With these features in the language, Russian and other Slavic languages are one of the hardest languages to learn in the world. Rusf (talk) 16:02, 8 July 2010 (UTC)

Cossacks and Kazakhs
Russian word "казак" is translated to English as "cossack". The word "kazakh" in Russian is written as "казах". These are two different words with different meanings. — Preceding unsigned comment added by 188.134.35.216 (talk) 21:40, 24 October 2011 (UTC)

Listify decision at CfD
The following list of word were contained in Category:Russian loanwords which was deleted in favor of adding them to this list. The discussion was from January and this still was not done. So the contents are being listed here so that those who are familiar with the way the list is set up can add the ones that are not already there. I checked some and they were not in the list.

Aerosani, Afghanka, Alkonost, Antonovka, Artel, Ataman, Bannik, Bogatyr, Borzoi, Boyar, Budenovka, Buran (wind), Cheburashka, Domra, Drioma, Droshky, Dvinia, Fenya, Fortochka, Garmon, Gavreau, Golomyanka, Gopnik, Gorodki, Gosplan, Guberniya, Gusli, Gzhel, Hucho taimen, Indrik, Inorodtsy, Inostrancevia, Kapustnik, Katyusha rocket launcher, Kazakhstania, Khokhloma, Khorovod, Khozyain, Kikimora, Kokoshnik, Kokoshnik (architecture), Kolkhoz, Kolobok, Kosovorotka, Kotlassia, Krushcheby, Kulich, Laika (dog breed), Lapta (game), Lubok, Maslenitsa, Naukograd, Oblast, Okolnichy, Omul, Ossetra, Ostrog (fortress), Ovinnik, Paskha (dish), Pernach, Petrushka, Pirozhki, Pobedit, Podpolkovnik, Podruchnik, Podstakannik, Posad, Posadnik, Poshlost, Poustinia, Prospekt (street), Rabfak, Raion, Raskol, Rassolnik, Runet (terminology), Samosely, Sarafan, Shishiga, Smerd, Sobornost, Solyanka, Sotnik, Sovnya, Soyuz, Stanitsa, Steppe, Stilyagi, Subbotnik, Sushki, Svirel, Syrniki, Talik, Tarantass, Technicum, Telega, Telnyashka, Telogreika, Treshchotka, Tsaritsa, Tubeteika, Udarnik, Ukha, Ushkuiniks, Uyezd, Valenki, Veche, Venyukovia, Volost, Vostok, Yorsh, Zapoy, Zastruga, Zhaleika

Thanks. Vegaswikian (talk) 21:12, 9 August 2013 (UTC)

Sections
I propose to move some words like 'sputnik' and 'cosmonaut' from the common list to some other category, possibly new. In English, they refer exclusively to the Soviet/Russian space program. In that sense, they are not common as are the words 'mammoth' and 'babushka'. On the other hand, the Cuisine and Political and possibly other sections mix words that are fairly obscure in the English-speaking world and are only used in Russian context, such as 'coulibiac', 'glasnost' and even 'DOSAAF' (!) with common words like 'tsar '(which is often used not to refer to a Russian monarch but to describe a ruthless ruler etc., often ironically) and 'vodka'. Sergivs-en (talk) 05:29, 17 November 2013 (UTC)

 * This is exactly what I was expecting to see in this entry: words of Russian origin in common English usage not connected with Russia: Tsar, Mammoth, samizdat, etc. Although 'Babushka' is pretty common, I only ever see it used in connection with Russian grannies. Similarly, a samovar is a very Russian thing, so I wouldn't include it in a list of borrowings. Perhaps it's reasonable to have a section for generally understood but still very Ruso-specific terms, but I"m not sure how useful that would be. SleekWeasel (talk) 11:28, 18 November 2015 (UTC)

and...
~Yurt, a particular kind of portable housing typical of Mongolia; probably from Mongolian /gehr/.

~ -nik is not explained.

~ A blin (pl. blini) or blintchik (pl. blintchiki) is a type of thin pancakes which typically lacks a leavening agent.

~ borscht? This soup is Ukrainian, but maybe the word entered English from Russian.

~ kasha - In English: buckwheat groats, but in Russian cereal grains in general. Kdammers (talk) 20:45, 11 October 2015 (UTC)

Okhran(k)a
The article states "Okhrana in full The Okhrannoye otdeleniye".

Should be "Okhranka" actually, the suffix -k is common for such abbreviations (Elektrichka is an example, short for "Elektricheskiy poyezd", "electrical train"). — Preceding unsigned comment added by 2A02:A31A:E040:B300:8256:F2FF:FEEA:39CB (talk) 00:58, 18 January 2017 (UTC)


text:
Prüm

Prüm is a town in the Westeifel (Rhineland-Palatinate), Germany. Formerly a district capital, today it is the administrative seat of the Verbandsgemeinde ("collective municipality") Prüm.

Geography
Prüm lies on the river Prüm (a tributary of the Sauer) at the southeastern end of the Schneifel, which is 697 m high. Prüm is eponymous for the Prüm syncline (Ger. Prümer Kalkmulde), the largest of the Eifel-lime-synclines. Here, the only GSSP-point in Germany identifies the geological border between the lower Devonian Emsian and the middle Devonian Eifelian.

History
See main article on the town's former monastery, Prüm Abbey. In 2005, the Prüm Convention was signed in the city by several European countries.

Ninety-two percent of the town was destroyed by bombing and ground fighting during the Second World War. In 1949, it was wrecked again by an explosion on the Kalvarienberg hill caused by a fire in an underground ammunition bunker. Twelve people were killed, 15 injured and 965 left homeless.

Economy
Among the largest employers in the region are MUH Arla, Stihl, Streif, Prüm-Türenwerk and Tesla Grohmann Automation. MUH Arla has its head office at Pronsfeld, 10 kilometres away.

Transport
Since 1980 it has not been possible to take the train to Prüm, with the exception of freight trains that operated up to the end of the 1990s. In December 2000 the last train went through Prüm, and this was a special event. Since that time, the rail tracks have been dismantled.

The federal highway B265 and B410 cross in Prüm, the autobahn A60 and B51 also run near the city.

Prüm Air Station is located just outside Prüm and is operated by the United States Air Force.

Prümer Sommer
In July and August Prüm Summer takes place. It begins with a market and a music competition on the streets on the last Sunday in June. During the next eight Thursdays, various guests meet at the town hall, where there are various competitions, such as a beer jug lift and trunk sawing. There is also a bicycle rally, a fashion show, and dances included in the program.

International relations
Prüm is twinned with: Bangor, Northern Ireland; Monthermé (France, since 1962); Fort Madison, Iowa (United States, since 1998 )

Notable people

 * Regino of Prüm, medieval monk and chronicler
 * It seems that Pepin the Hunchback, first son of Charlemagne, was in exile in a monastery in Prüm from ca. 793 to his death in 813.

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

title: Prüm


text:
Brauer group

In mathematics, the Brauer group of a field K is an abelian group whose elements are Morita equivalence classes of central simple algebras over K, with addition given by the tensor product of algebras. It was defined by the algebraist Richard Brauer.

The Brauer group arose out of attempts to classify division algebras over a field. It can also be defined in terms of Galois cohomology. More generally, the Brauer group of a scheme is defined in terms of Azumaya algebras, or equivalently using projective bundles.

Construction
A central simple algebra (CSA) over a field K is a finite-dimensional associative K-algebra A such that A is a simple ring and the center of A is equal to K. Note that CSAs are in general not division algebras, though CSAs can be used to classify division algebras.

For example, the complex numbers C form a CSA over themselves, but not over R (the center is C itself, hence too large to be CSA over R). The finite-dimensional division algebras with center R (that means the dimension over R is finite) are the real numbers and the quaternions by a theorem of Frobenius, while any matrix ring over the reals or quaternions – M(n, R) or M(n, H) – is a CSA over the reals, but not a division algebra (if n > 1).

We obtain an equivalence relation on CSAs over K by the Artin–Wedderburn theorem (Wedderburn's part, in fact), to express any CSA as a M(n, D) for some division algebra D. If we look just at D, that is, if we impose an equivalence relation identifying M(m, D) with M(n, D) for all positive integers m and n, we get the Brauer equivalence relation on CSAs over K. The elements of the Brauer group are the Brauer equivalence classes of CSAs over K.

Given central simple algebras A and B, one can look at their tensor product A ⊗ B as a K-algebra. It turns out that this is always central simple. A slick way to see this is to use a characterization: a central simple algebra A over K is a K-algebra that becomes a matrix ring when we extend the field of scalars to an algebraic closure of K. This result also shows that the dimension of a central simple algebra A as a K-vector space is always a square. The degree of A is defined to be the square root of its dimension.

As a result, the isomorphism classes of CSAs over K form a monoid under tensor product, compatible with Brauer equivalence, and the Brauer classes are all invertible: the inverse of an algebra A is given by its opposite algebra Aop (the opposite ring with the same action by K since the image of K → A is in the center of A). Explicitly, for a CSA A we have A ⊗ Aop = M(n2, K), where n is the degree of A over K.

The Brauer group of any field is a torsion group. In more detail, define the period of a central simple algebra A over K to be its order as an element of the Brauer group. Define the index of A to be the degree of the division algebra that is Brauer equivalent to A. Then the period of A divides the index of A (and hence is finite).

Examples

 * In the following cases, every finite-dimensional central division algebra over a field K is K itself, so that the Brauer group Br(K) is trivial:
 * K is an algebraically closed field.
 * K is a finite field (Wedderburn's theorem). Equivalently, every finite division ring is commutative.
 * K is the function field of an algebraic curve over an algebraically closed field (Tsen's theorem). More generally, the Brauer group vanishes for any C1 field.
 * K is an algebraic extension of Q containing all roots of unity.
 * The Brauer group Br R of the real numbers is the cyclic group of order two. There are just two non-isomorphic real division algebras with center R: R itself and the quaternion algebra H. Since H ⊗ H ≅ M(4, R), the class of H has order two in the Brauer group.
 * Let K be a non-Archimedean local field, meaning that K is complete under a discrete valuation with finite residue field. Then Br K is isomorphic to Q/Z.

Severi–Brauer varieties
Another important interpretation of the Brauer group of a field K is that it classifies the projective varieties over K that become isomorphic to projective space over an algebraic closure of K. Such a variety is called a Severi–Brauer variety, and there is a one-to-one correspondence between the isomorphism classes of Severi–Brauer varieties of dimension n − 1 over K and the central simple algebras of degree n over K.

For example, the Severi–Brauer varieties of dimension 1 are exactly the smooth conics in the projective plane over K. For a field K of characteristic not 2, every conic over K is isomorphic to one of the form ax2 + by2 = z2 for some nonzero elements a and b of K. The corresponding central simple algebra is the quaternion algebra
 * $$(a,b) = K\langle i,j\rangle/(i^2=a, j^2=b, ij=-ji).$$

The conic is isomorphic to the projective line P1 over K if and only if the corresponding quaternion algebra is isomorphic to the matrix algebra M(2, K).

Cyclic algebras
For a positive integer n, let K be a field in which n is invertible such that K contains a primitive nth root of unity ζ. For nonzero elements a and b of K, the associated cyclic algebra is the central simple algebra of degree n over K defined by
 * $$(a,b)_{\zeta} = K\langle u,v\rangle/(u^n=a, v^n=b, uv=\zeta vu).$$

Cyclic algebras are the best-understood central simple algebras. (When n is not invertible in K or K does not have a primitive nth root of unity, a similar construction gives the cyclic algebra (χ, a) associated to a cyclic Z/n-extension χ of K and a nonzero element a of K.)

The Merkurjev–Suslin theorem in algebraic K-theory has a strong consequence about the Brauer group. Namely, for a positive integer n, let K be a field in which n is invertible such that K contains a primitive nth root of unity. Then the subgroup of the Brauer group of K killed by n is generated by cyclic algebras of degree n. Equivalently, any division algebra of period dividing n is Brauer equivalent to a tensor product of cyclic algebras of degree n. Even for a prime number p, there are examples showing that a division algebra of period p need not be actually isomorphic to a tensor product of cyclic algebras of degree p.

It is a major open problem (raised by Albert) whether every division algebra of prime degree over a field is cyclic. This is true if the degree is 2 or 3, but the problem is wide open for primes at least 5. The known results are only for special classes of fields. For example, if K is a global field or local field, then a division algebra of any degree over K is cyclic, by Albert–Brauer–Hasse–Noether. A "higher-dimensional" result in the same direction was proved by Saltman: if K is a field of transcendence degree 1 over the local field Qp, then every division algebra of prime degree l ≠ p over K is cyclic.

The period-index problem
For any central simple algebra A over a field K, the period of A divides the index of A, and the two numbers have the same prime factors. The period-index problem is to bound the index in terms of the period, for fields K of interest. For example, if A is a central simple algebra over a local field or global field, then Albert–Brauer–Hasse–Noether showed that the index of A is equal to the period of A.

For a central simple algebra A over a field K of transcendence degree n over an algebraically closed field, it is conjectured that ind(A) divides per(A)n−1. This is true for n ≤ 2, the case n = 2 being an important advance by de Jong, sharpened in positive characteristic by de Jong–Starr and Lieblich.

Class field theory
The Brauer group plays an important role in the modern formulation of class field theory. If Kv is a non-Archimedean local field, local class field theory gives a canonical isomorphism invv : Br Kv → Q/Z, the Hasse invariant.

The case of a global field K (such as a number field) is addressed by global class field theory. If D is a central simple algebra over K and v is a place of K, then D ⊗ Kv is a central simple algebra over Kv, the completion of K at v. This defines a homomorphism from the Brauer group of K into the Brauer group of Kv. A given central simple algebra D splits for all but finitely many v, so that the image of D under almost all such homomorphisms is 0. The Brauer group Br K fits into an exact sequence constructed by Hasse:
 * $$0 \rightarrow \operatorname{Br}K \rightarrow \bigoplus_{v \in S} \operatorname{Br}K_v \rightarrow \mathbf{Q}/\mathbf{Z} \rightarrow 0,$$

where S is the set of all places of K and the right arrow is the sum of the local invariants; the Brauer group of the real numbers is identified with (1/2)Z/Z. The injectivity of the left arrow is the content of the Albert–Brauer–Hasse–Noether theorem.

The fact that the sum of all local invariants of a central simple algebra over K is zero is a typical reciprocity law. For example, applying this to a quaternion algebra (a, b) over Q gives the quadratic reciprocity law.

Galois cohomology
For an arbitrary field K, the Brauer group can be expressed in terms of Galois cohomology as follows:
 * $$\operatorname{Br}K \cong H^2(K, G_\text{m}),$$

where Gm denotes the multiplicative group, viewed as an algebraic group over K. More concretely, the cohomology group indicated means H 2(Gal(Ks/K), Ks*), where Ks denotes a separable closure of K.

The isomorphism of the Brauer group with a Galois cohomology group can be described as follows. The automorphism group of the algebra of n-by-n matrices is the projective linear group PGL(n). Since all central simple algebras over K become isomorphic to the matrix algebra over a separable closure of K, the set of isomorphism classes of central simple algebras of degree n over K can be identified with the Galois cohomology set H1(K, PGL(n)). The class of a central simple algebra in H 2(K, Gm) is the image of its class in H1 under the boundary homomorphism
 * $$H^1(K, \operatorname{PGL}(n)) \rightarrow H^2(K, G_\text{m})$$

associated to the short exact sequence 1 → Gm → GL(n) → PGL(n) → 1.

The Brauer group of a scheme
The Brauer group was generalized from fields to commutative rings by Auslander and Goldman. Grothendieck went further by defining the Brauer group of any scheme.

There are two ways of defining the Brauer group of a scheme X, using either Azumaya algebras over X or projective bundles over X. The second definition involves projective bundles that are locally trivial in the étale topology, not necessarily in the Zariski topology. In particular, a projective bundle is defined to be zero in the Brauer group if and only if it is the projectivization of some vector bundle.

The cohomological Brauer group of a quasi-compact scheme X is defined to be the torsion subgroup of the étale cohomology group H 2(X, Gm). (The whole group H 2(X, Gm) need not be torsion, although it is torsion for regular schemes X.) The Brauer group is always a subgroup of the cohomological Brauer group. Gabber showed that the Brauer group is equal to the cohomological Brauer group for any scheme with an ample line bundle (for example, any quasi-projective scheme over a commutative ring).

The whole group H 2(X, Gm) can be viewed as classifying the gerbes over X with structure group Gm.

For smooth projective varieties over a field, the Brauer group is a birational invariant. It has been fruitful. For example, when X is also rationally connected over the complex numbers, the Brauer group of X is isomorphic to the torsion subgroup of the singular cohomology group H 3(X, Z), which is therefore a birational invariant. Artin and Mumford used this description of the Brauer group to give the first example of a unirational variety X over C that is not stably rational (that is, no product of X with a projective space is rational).

Relation to the Tate conjecture
Artin conjectured that every proper scheme over the integers has finite Brauer group. This is far from known even in the special case of a smooth projective variety X over a finite field. Indeed, the finiteness of the Brauer group for surfaces in that case is equivalent to the Tate conjecture for divisors on X, one of the main problems in the theory of algebraic cycles.

For a regular integral scheme of dimension 2 which is flat and proper over the ring of integers of a number field, and which has a section, the finiteness of the Brauer group is equivalent to the finiteness of the Tate–Shafarevich group Ш for the Jacobian variety of the general fiber (a curve over a number field). The finiteness of Ш is a central problem in the arithmetic of elliptic curves and more generally abelian varieties.

The Brauer–Manin obstruction
Let X be a smooth projective variety over a number field K. The Hasse principle would predict that if X has a rational point over all completions Kv of K, then X has a K-rational point. The Hasse principle holds for some special classes of varieties, but not in general. Manin used the Brauer group of X to define the Brauer–Manin obstruction, which can be applied in many cases to show that X has no K-points even when X has points over all completions of K.

title: Brauer group


text:
Talk:Melvin Defleur

—Preceding unsigned comment added by Businessman332211 (talk • contribs) 21:27, 5 November 2007 (UTC)

Untitled
Examine for copyvio. specially first line - Hemanshu 10:26, 16 Dec 2003 (UTC)

External links modified
Hello fellow Wikipedians,

I have just modified one external link on Melvin Defleur. Please take a moment to review my edit. If you have any questions, or need the bot to ignore the links, or the page altogether, please visit this simple FaQ for additional information. I made the following changes:
 * Added archive https://web.archive.org/web/20020612024412/http://www.bu.edu/com/mcapr/masscom/mdefleur.html to http://www.bu.edu/com/mcapr/masscom/mdefleur.html

When you have finished reviewing my changes, you may follow the instructions on the template below to fix any issues with the URLs.

Cheers.— InternetArchiveBot  (Report bug) 06:26, 3 December 2017 (UTC)

title: Talk:Melvin Defleur


text:
Central simple algebra

In ring theory and related areas of mathematics a central simple algebra (CSA) over a field K is a finite-dimensional associative K-algebra A which is simple, and for which the center is exactly K. (Note that not every simple algebra is a central simple algebra over its center: for instance, if K is a field of characteristic 0, then the Weyl algebra $$K[X,\partial_X]$$ is a simple algebra with center K, but is not a central simple algebra over K as it has infinite dimension as a K-module.)

For example, the complex numbers C form a CSA over themselves, but not over the real numbers R (the center of C is all of C, not just R). The quaternions H form a 4-dimensional CSA over R, and in fact represent the only non-trivial element of the Brauer group of the reals (see below).

Given two central simple algebras A ~ M(n,S) and B ~ M(m,T) over the same field F, A and B are called similar (or Brauer equivalent) if their division rings S and T are isomorphic. The set of all equivalence classes of central simple algebras over a given field F, under this equivalence relation, can be equipped with a group operation given by the tensor product of algebras. The resulting group is called the Brauer group Br(F) of the field F. It is always a torsion group.

Properties

 * According to the Artin–Wedderburn theorem a finite-dimensional simple algebra A is isomorphic to the matrix algebra M(n,S) for some division ring S. Hence, there is a unique division algebra in each Brauer equivalence class.
 * Every automorphism of a central simple algebra is an inner automorphism (this follows from the Skolem–Noether theorem).
 * The dimension of a central simple algebra as a vector space over its centre is always a square: the degree is the square root of this dimension. The Schur index of a central simple algebra is the degree of the equivalent division algebra: it depends only on the Brauer class of the algebra.
 * The period or exponent of a central simple algebra is the order of its Brauer class as an element of the Brauer group. It is a divisor of the index, and the two numbers are composed of the same prime factors.
 * If S is a simple subalgebra of a central simple algebra A then dimF S divides dimF A.
 * Every 4-dimensional central simple algebra over a field F is isomorphic to a quaternion algebra; in fact, it is either a two-by-two matrix algebra, or a division algebra.
 * If D is a central division algebra over K for which the index has prime factorisation
 * $$\mathrm{ind}(D) = \prod_{i=1}^r p_i^{m_i} \ $$
 * then D has a tensor product decomposition
 * $$D = \bigotimes_{i=1}^r D_i \ $$
 * where each component Di is a central division algebra of index $$p_i^{m_i}$$, and the components are uniquely determined up to isomorphism.

Splitting field
We call a field E a splitting field for A over K if A⊗E is isomorphic to a matrix ring over E. Every finite dimensional CSA has a splitting field: indeed, in the case when A is a division algebra, then a maximal subfield of A is a splitting field. In general by theorems of Wedderburn and Koethe there is a splitting field which is a separable extension of K of degree equal to the index of A, and this splitting field is isomorphic to a subfield of A. As an example, the field C splits the quaternion algebra H over R with

 * $$ t + x \mathbf{i} + y \mathbf{j} + z \mathbf{k} \leftrightarrow

\left({\begin{array}{*{20}c} t + x i & y + z i \\ -y + z i & t - x i \end{array}}\right). $$

We can use the existence of the splitting field to define reduced norm and reduced trace for a CSA A. Map A to a matrix ring over a splitting field and define the reduced norm and trace to be the composite of this map with determinant and trace respectively. For example, in the quaternion algebra H, the splitting above shows that the element t + x i + y j + z k has reduced norm t2 + x2 + y2 + z2 and reduced trace 2t.

The reduced norm is multiplicative and the reduced trace is additive. An element a of A is invertible if and only if its reduced norm in non-zero: hence a CSA is a division algebra if and only if the reduced norm is non-zero on the non-zero elements.

Generalization
CSAs over a field K are a non-commutative analog to extension fields over K – in both cases, they have no non-trivial 2-sided ideals, and have a distinguished field in their center, though a CSA can be non-commutative and need not have inverses (need not be a division algebra). This is of particular interest in noncommutative number theory as generalizations of number fields (extensions of the rationals Q); see noncommutative number field.

title: Central simple algebra


text:
Joseph Bradley Varnum

Joseph Bradley Varnum (January 29, 1750/1751 – September 21, 1821) was an American politician from Massachusetts. He served as a U.S. representative and United States senator, and held leadership positions in both bodies. He was a member of the Democratic-Republican Party.

Born in Dracut in the Province of Massachusetts Bay, Varnum was the son of farmer, militia officer and local official Samuel Varnum and Mary Prime. He received a limited formal education, but became a self-taught scholar. Varnum became a farmer, and at age 18 received his commission as a captain in the Massachusetts militia. He commanded Dracut's militia company during the American Revolution and remained in the militia afterwards, eventually attaining the rank of major general in 1805.

Varnum took part in the government of Massachusetts following independence, including as a member of the Massachusetts House of Representatives from 1780 to 1785 and a member of the Massachusetts State Senate from 1786 to 1795. Despite not being an attorney, Varnum also served as a judge, including terms as a Justice of the Massachusetts Court of Common Pleas and Chief Justice of the Massachusetts Court of General Sessions. He was a member of the U.S. House from 1795 to 1811, and was Speaker of the House from 1807 to 1811. Varnum served in the U.S. Senate from 1811 to 1817, and was the Senate's president pro tempore from 1813 to 1814.

After leaving the U.S. Senate, Varnum served in the Massachusetts State Senate until his death. He died in Dracut on September 21, 1821, and was buried at Varnum Cemetery in Dracut.

Biography
Joseph Bradley Varnum was born in Dracut, Massachusetts, in Middlesex County, on January 29, 1750, or 1751.

At the age of eighteen, he was commissioned captain by the committee of Massachusetts Bay Colony, and in 1787 colonel by the Commonwealth of Massachusetts. He was made brigadier general in 1802, and in 1805 major general of the state militia, holding the latter office at his death in 1821.

After serving in the Massachusetts militia during the American Revolutionary War, Varnum helped to destroy the Shays insurrection before he was elected to the Massachusetts House of Representatives (1780–1785) and then the Massachusetts State Senate (1786–1795). He also served as a Justice of the Massachusetts Court of Common Pleas and as Chief Justice of the Massachusetts Court of General Sessions.

In 1794, Varnum was elected to the U.S. House of Representatives, where he served from March 4, 1795, until his resignation on June 29, 1811. He was one of six Democratic-Republican representatives to oppose the Twelfth Amendment to the United States Constitution. During his last four years in the House, he served as its Speaker.

Varnum was elected to the U.S. Senate in 1811 to fill the vacancy in the term. He became the only U.S. Senator from the Democratic-Republican Party in Massachusetts history.

Varnum served as President pro tempore of the U.S. Senate from December 6, 1813, to February 3, 1814, during the Thirteenth Congress. He was also the Chair of the Senate Committee on Militia during the Fourteenth Congress.

After returning to Massachusetts in 1817, Varnum again served in the Massachusetts State Senate, until his death on September 21, 1821.

Varnum died in Dracut, and is interred in Varnum Cemetery in that town. His brother was Major General James Mitchell Varnum who commanded the 1st Rhode Island Regiment from 1775 to 1777, served as a brigade commander at the Battle of Rhode Island and later served as the major general in command of the Rhode Island Militia.

Slavery
Henry Wilson, in his History of Slavery, quotes Varnum in the debate on the bill for the government of the Mississippi Territory before the United States House of Representatives in March 1798 as having been very strong and outspoken in his opposition to Negro servitude. Varnum developed a strong friendship with Silas Royal, a former slave freed by the Varnum family, who also served with him during the war.

On March 3, 1805, Varnum submitted a Massachusetts Proposition to amend the Constitution and Abolish the Slave Trade. This proposition was tabled until 1807, when under Varnum's leadership the amendment moved through Congress and passed both houses on March 2, 1807. President Thomas Jefferson signed it into law on March 3, 1807.

title: Joseph Bradley Varnum


text:
Hebbian theory

Hebbian theory is a neuropsychological theory claiming that an increase in synaptic efficacy arises from a presynaptic cell's repeated and persistent stimulation of a postsynaptic cell. It is an attempt to explain synaptic plasticity, the adaptation of brain neurons during the learning process. It was introduced by Donald Hebb in his 1949 book The Organization of Behavior. The theory is also called Hebb's rule, Hebb's postulate, and cell assembly theory. Hebb states it as follows:

"Let us assume that the persistence or repetition of a reverberatory activity (or 'trace') tends to induce lasting cellular changes that add to its stability. ... When an axon of cell A is near enough to excite a cell B and repeatedly or persistently takes part in firing it, some growth process or metabolic change takes place in one or both cells such that A’s efficiency, as one of the cells firing B, is increased."

The theory is often summarized as "Neurons that fire together, wire together." However, Hebb emphasized that cell A needs to "take part in firing" cell B, and such causality can occur only if cell A fires just before, not at the same time as, cell B. This aspect of causation in Hebb's work foreshadowed what is now known about spike-timing-dependent plasticity, which requires temporal precedence.

The theory attempts to explain associative or Hebbian learning, in which simultaneous activation of cells leads to pronounced increases in synaptic strength between those cells. It also provides a biological basis for errorless learning methods for education and memory rehabilitation. In the study of neural networks in cognitive function, it is often regarded as the neuronal basis of unsupervised learning.

Hebbian engrams and cell assembly theory
Hebbian theory concerns how neurons might connect themselves to become engrams. Hebb's theories on the form and function of cell assemblies can be understood from the following:

"The general idea is an old one, that any two cells or systems of cells that are repeatedly active at the same time will tend to become 'associated' so that activity in one facilitates activity in the other."

Hebb also wrote: "When one cell repeatedly assists in firing another, the axon of the first cell develops synaptic knobs (or enlarges them if they already exist) in contact with the soma of the second cell."

[D. Alan Allport] posits additional ideas regarding cell assembly theory and its role in forming engrams, along the lines of the concept of auto-association, described as follows:

"If the inputs to a system cause the same pattern of activity to occur repeatedly, the set of active elements constituting that pattern will become increasingly strongly inter-associated. That is, each element will tend to turn on every other element and (with negative weights) to turn off the elements that do not form part of the pattern. To put it another way, the pattern as a whole will become 'auto-associated'. We may call a learned (auto-associated) pattern an engram."

Work in the laboratory of Eric Kandel has provided evidence for the involvement of Hebbian learning mechanisms at synapses in the marine gastropod Aplysia californica. Experiments on Hebbian synapse modification mechanisms at the central nervous system synapses of vertebrates are much more difficult to control than are experiments with the relatively simple peripheral nervous system synapses studied in marine invertebrates. Much of the work on long-lasting synaptic changes between vertebrate neurons (such as long-term potentiation) involves the use of non-physiological experimental stimulation of brain cells. However, some of the physiologically relevant synapse modification mechanisms that have been studied in vertebrate brains do seem to be examples of Hebbian processes. One such study reviews results from experiments that indicate that long-lasting changes in synaptic strengths can be induced by physiologically relevant synaptic activity working through both Hebbian and non-Hebbian mechanisms.

Principles
From the point of view of artificial neurons and artificial neural networks, Hebb's principle can be described as a method of determining how to alter the weights between model neurons. The weight between two neurons increases if the two neurons activate simultaneously, and reduces if they activate separately. Nodes that tend to be either both positive or both negative at the same time have strong positive weights, while those that tend to be opposite have strong negative weights.

The following is a formulaic description of Hebbian learning: (many other descriptions are possible)

 * $$\,w_{ij}=x_ix_j$$

where $$w_{ij} $$ is the weight of the connection from neuron $$ j $$ to neuron $$ i $$ and $$ x_i $$ the input for neuron $$ i $$. Note that this is pattern learning (weights updated after every training example). In a Hopfield network, connections $$w_{ij} $$ are set to zero if $$i=j $$ (no reflexive connections allowed). With binary neurons (activations either 0 or 1), connections would be set to 1 if the connected neurons have the same activation for a pattern.

When several training patterns are used the expression becomes an average of individual ones:

 * $$w_{ij} = \frac{1}{p} \sum_{k=1}^p x_i^k x_j^k$$

where $$w_{ij} $$ is the weight of the connection from neuron $$ j $$ to neuron $$ i $$, $$ p $$ is the number of training patterns and $$x_{i}^k$$ the $$ k $$-th input for neuron $$ i $$. This is learning by epoch (weights updated after all the training examples are presented), being last term applicable to both discrete and continuous training sets. Again, in a Hopfield network, connections $$w_{ij} $$ are set to zero if $$i=j $$ (no reflexive connections).

A variation of Hebbian learning that takes into account phenomena such as blocking and many other neural learning phenomena is the mathematical model of Harry Klopf. Klopf's model reproduces a great many biological phenomena, and is also simple to implement.

Relationship to unsupervised learning, stability, and generalization
Because of the simple nature of Hebbian learning, based only on the coincidence of pre- and post-synaptic activity, it may not be intuitively clear why this form of plasticity leads to meaningful learning. However, it can be shown that Hebbian plasticity does pick up the statistical properties of the input in a way that can be categorized as unsupervised learning.

This can be mathematically shown in a simplified example. Let us work under the simplifying assumption of a single rate-based neuron of rate $$y(t)$$, whose inputs have rates $$x_1(t) ... x_N(t)$$. The response of the neuron $$y(t)$$ is usually described as a linear combination of its input, $$\sum_i w_ix_i$$, followed by a response function $$f$$:
 * $$y = f\left(\sum_{i=1}^N w_i x_i \right).$$

As defined in the previous sections, Hebbian plasticity describes the evolution in time of the synaptic weight $$w$$:
 * $$\frac{dw_i}{dt} = \eta x_i y.$$

Assuming, for simplicity, an identity response function $$f(a)=a$$, we can write
 * $$\frac{dw_i}{dt} = \eta x_i \sum_{j=1}^N w_j x_j$$

or in matrix form:
 * $$\frac{d\mathbf{w}}{dt} = \eta \mathbf{x}\mathbf{x}^T\mathbf{w}.$$

As in the previous chapter, if training by epoch is done an average $$\langle \dots \rangle$$ over discrete or continuous (time) training set of $$\mathbf{x}$$ can be done:$$\frac{d\mathbf{w}}{dt} = \langle \eta \mathbf{x}\mathbf{x}^T\mathbf{w} \rangle = \eta \langle \mathbf{x}\mathbf{x}^T\rangle\mathbf{w} = \eta C \mathbf{w}.$$where $$C = \langle\, \mathbf{x}\mathbf{x}^T \rangle$$ is the correlation matrix of the input under the additional assumption that $$\langle\mathbf{x}\rangle = 0$$ (i.e. the average of the inputs is zero). This is a system of $$N$$ coupled linear differential equations. Since $$C$$ is symmetric, it is also diagonalizable, and the solution can be found, by working in its eigenvectors basis, to be of the form
 * $$\mathbf{w}(t) = k_1e^{\eta\alpha_1 t}\mathbf{c}_1 + k_2e^{\eta\alpha_2 t}\mathbf{c}_2 + ... + k_Ne^{\eta\alpha_N t}\mathbf{c}_N$$

where $$k_i$$ are arbitrary constants, $$\mathbf{c}_i$$ are the eigenvectors of $$C$$ and $$\alpha_i$$ their corresponding eigen values. Since a correlation matrix is always a positive-definite matrix, the eigenvalues are all positive, and one can easily see how the above solution is always exponentially divergent in time. This is an intrinsic problem due to this version of Hebb's rule being unstable, as in any network with a dominant signal the synaptic weights will increase or decrease exponentially. Intuitively, this is because whenever the presynaptic neuron excites the postsynaptic neuron, the weight between them is reinforced, causing an even stronger excitation in the future, and so forth, in a self-reinforcing way. One may think a solution is to limit the firing rate of the postsynaptic neuron by adding a non-linear, saturating response function $$f$$, but in fact, it can be shown that for any neuron model, Hebb's rule is unstable. Therefore, network models of neurons usually employ other learning theories such as BCM theory, Oja's rule, or the generalized Hebbian algorithm.

Regardless, even for the unstable solution above, one can see that, when sufficient time has passed, one of the terms dominates over the others, and
 * $$\mathbf{w}(t) \approx e^{\eta\alpha^* t}\mathbf{c}^*$$

where $$\alpha^*$$ is the largest eigenvalue of $$C$$. At this time, the postsynaptic neuron performs the following operation:
 * $$y \approx e^{\eta\alpha^* t}\mathbf{c}^* \mathbf{x}$$

Because, again, $$\mathbf{c}^*$$ is the eigenvector corresponding to the largest eigenvalue of the correlation matrix between the $$x_i$$s, this corresponds exactly to computing the first principal component of the input.

This mechanism can be extended to performing a full PCA (principal component analysis) of the input by adding further postsynaptic neurons, provided the postsynaptic neurons are prevented from all picking up the same principal component, for example by adding lateral inhibition in the postsynaptic layer. We have thus connected Hebbian learning to PCA, which is an elementary form of unsupervised learning, in the sense that the network can pick up useful statistical aspects of the input, and "describe" them in a distilled way in its output.

Limitations
Despite the common use of Hebbian models for long-term potentiation, Hebb's principle does not cover all forms of synaptic long-term plasticity. Hebb did not postulate any rules for inhibitory synapses, nor did he make predictions for anti-causal spike sequences (presynaptic neuron fires after the postsynaptic neuron). Synaptic modification may not simply occur only between activated neurons A and B, but at neighboring synapses as well. All forms of hetero synaptic and homeostatic plasticity are therefore considered non-Hebbian. An example is retrograde signaling to presynaptic terminals. The compound most commonly identified as fulfilling this retrograde transmitter role is nitric oxide, which, due to its high solubility and diffusivity, often exerts effects on nearby neurons. This type of diffuse synaptic modification, known as volume learning, is not included in the traditional Hebbian model.

Hebbian learning account of mirror neurons
Hebbian learning and spike-timing-dependent plasticity have been used in an influential theory of how mirror neurons emerge. Mirror neurons are neurons that fire both when an individual performs an action and when the individual sees or hears another perform a similar action. The discovery of these neurons has been very influential in explaining how individuals make sense of the actions of others, by showing that, when a person perceives the actions of others, the person activates the motor programs which they would use to perform similar actions. The activation of these motor programs then adds information to the perception and helps predict what the person will do next based on the perceiver's own motor program. A challenge has been to explain how individuals come to have neurons that respond both while performing an action and while hearing or seeing another perform similar actions.

Christian Keysers and David Perrett suggested that as an individual performs a particular action, the individual will see, hear, and feel the performing of the action. These re-afferent sensory signals will trigger activity in neurons responding to the sight, sound, and feel of the action. Because the activity of these sensory neurons will consistently overlap in time with those of the motor neurons that caused the action, Hebbian learning predicts that the synapses connecting neurons responding to the sight, sound, and feel of an action and those of the neurons triggering the action should be potentiated. The same is true while people look at themselves in the mirror, hear themselves babble, or are imitated by others. After repeated experience of this re-afference, the synapses connecting the sensory and motor representations of an action are so strong that the motor neurons start firing to the sound or the vision of the action, and a mirror neuron is created.

Evidence for that perspective comes from many experiments that show that motor programs can be triggered by novel auditory or visual stimuli after repeated pairing of the stimulus with the execution of the motor program (for a review of the evidence, see Giudice et al., 2009 ). For instance, people who have never played the piano do not activate brain regions involved in playing the piano when listening to piano music. Five hours of piano lessons, in which the participant is exposed to the sound of the piano each time they press a key is proven sufficient to trigger activity in motor regions of the brain upon listening to piano music when heard at a later time. Consistent with the fact that spike-timing-dependent plasticity occurs only if the presynaptic neuron's firing predicts the post-synaptic neuron's firing, the link between sensory stimuli and motor programs also only seem to be potentiated if the stimulus is contingent on the motor program.

title: Hebbian theory


text:
John Danvers

Sir John Danvers (c. 1585–buried 28 April 1655) was an English courtier and politician who was one of the signatories of the death warrant of Charles I.

Life
Danvers was the third and youngest son of Sir John Danvers of Dauntsey, Wiltshire, by Elizabeth Neville. In his youth, he travelled through France and Italy, developing sophisticated tastes in gardening and architecture, which in later life he indulged at his house in Chelsea. In 1597 he entered the University of Padua as a student, prior to returning to England where he carried on his education at Winchester College (entered 1598), Brasenose College, Oxford (entered 1601) and Lincoln's Inn where he was a law student in 1612. Danvers was knighted by James I of England on 3 March 1609; and under Charles I became a gentleman of the privy chamber.

He sat as a member of parliament for Arundel in 1610, Montgomery Boroughs in the Addled Parliament of 1614, Oxford University in 1621, Newport (Isle of Wight) in 1624 and again for Oxford University from 1625 to 1629.

Danvers was engaged in mercantile transactions, and in 1624 he learned that the government were contemplating a seizure of the papers of the Virginia Company. With the aid of Edward Collingwood, the secretary, he had the whole of the records copied out and entrusted them to the care of Henry Wriothesley, 3rd Earl of Southampton, a family friend, who deposited them at his house at Titchfield, Hampshire.

Danvers fell into debt, and from 1630 to 1640 was apparently struggling with creditors. About 1640 he began an active political career in opposition to the king. He refused to contribute to the expenses of the king's expedition to Scotland in 1639, and was returned to the Short Parliament of 1640 by Oxford University. In 1642 he took up arms for the parliament, and was granted a colonel's commission which he held in command of the Wiltshire foot militia until 1650, but he did not play a prominent part in military affairs. He gives an account of the opening incidents of the war in letters written to friends from Chelsea in July and August 1642.

Danvers was ordered by the parliament to receive the Dutch ambassadors late in 1644, and on 10 October 1645 was returned to the house as member for Malmesbury in the place of Anthony Hungerford, disabled to sit. He took little part in the proceedings of the house, but was appointed a member of the commission nominated to try the king in January 1649. He was only twice absent from the meetings of the commission, and signed the death-warrant. In February of the same year Danvers was given a seat on the council of state, which he retained till the council's dissolution in 1653. He died at his house at Chelsea in April 1655, and was buried at Dauntsey. His name was in the Act of Attainder passed at the Restoration.

Gardener
At a young age Danvers acquired a fine garden and house at Chelsea: the latter he furnished sumptuously and curiously, and the former he laid out after the Italian manner. ' 'Twas Sir John Danvers of Chelsey,' John Aubrey writes, 'who first taught us the way of Italian gardens.' His house, called Danvers House, adjoined the mansion, once the home of Sir Thomas More, which was known in the seventeenth century as Buckingham and also as Beaufort House. Danvers House was pulled down in 1696 to make room for Danvers Street, therefore named after him.

Through his second marriage he came into possession of the estate of Lavington, Wiltshire, where he elaborately laid out gardens.

Marriages and family
In about March 1609 he married Magdalen Herbert (née Newport), widow of Richard Herbert, and mother of ten children, including George Herbert the poet, and Edward, Lord Herbert of Cherbury. She died in 1627.

On 10 July 1628, a year after the death of his first wife, Danvers, then reportedly aged 40, married Elizabeth, daughter of the late Ambrose Dauntsey, and granddaughter of Sir John Dauntsey. His second wife died on 9 July 1636.

His children by his second wife consisted of Henry (b. 5 December 1633), who inherited much of his uncle Henry's property, and died before his father in November 1654, when Thomas Fuller is stated to have preached the funeral sermon; Charles, who died in infancy; Elizabeth (b. 1 May 1629), who married Robert Danvers, self-styled Viscount Purbeck; and Mary, who died in infancy.

Danvers married a third time at Chelsea, on 6 January 1649, his wife being Grace Hewes, daughter of Thomas Hewes of Kemerton, Gloucestershire, and he had by her a son, John (b. 10 August 1650). Grace survived her husband and died in 1678.

Danvers' elder brothers were Charles Danvers and Henry Danvers. His brother Henry, who became Lord Danby, was a royalist, and died early in 1644; he left his property to his sister Lady Catherine Gargrave, wife of Sir Richard Gargrave, High Sheriff of Yorkshire. Still in pecuniary difficulties, Danvers resisted this disposition of his brother's property, and his influence with the parliamentary majority led the House of Commons to pass a resolution declaring that he had been deprived of his brother's estate 'for his affection and adhering to the parliament' (14 June 1644), and that Danvers's eldest son Henry was entitled to the property. The son Henry bequeathed the estate in his power to his sister Ann, who married Sir Henry Lee 3rd Baronet of the Lee Baronets of Ditchley in 1655, and had a daughter, Eleanor, who became the wife of James Bertie, 1st Earl of Abingdon. Lord Abingdon thus ultimately came into possession of the property at Chelsea.

title: John Danvers


text:
Surak

Surak is a fictional character in the backstory of the Star Trek television series and franchises. He is portrayed as the most important philosopher in the history of the planet Vulcan. During an Earth-like "modern age", when the Vulcans are technological but emotionally driven and violent, Surak founds a movement which reforms the Vulcan way of thinking and lifestyle and leads to the world of logically-reasoning and emotion-suppressing Vulcans known from the TV series. This period in Vulcan history is referred to as the "Time of Awakening".

The "Time of Awakening" is accompanied by violence unmatched in Vulcan history, according to the Star Trek: Enterprise episode "Awakening" (wherein Surak's mind is resurrected 1,800 years after his death to restore to modern Vulcans an uncorrupted version of his original philosophy). During the "Time of Awakening" a Vulcan schism of those who "sought a return to savage ways" and "marched beneath the raptor's wings" (later the symbol of the Romulan people) perpetrate a cataclysmic nuclear attack upon Surak and his enlightened society. Soon after Surak's death, these Vulcan recidivists abandon their homeworld to colonize the planets Romulus and Remus, forming what later comes to be known as the Romulan Star Empire. While Surak's philosophy of peace and logic survives for the next 2,000 years only as an underground movement within the emotional, warlike Romulan society (until further shepherded, in the Next Generation episode "Unification", by the elderly Ambassador Spock in the role of a latter-day successor to Surak), it continues to flourish on Vulcan to become its predominant philosophy.

The "Time of Awakening" and its "ironic violence" noted by Surak, which ends in nuclear holocaust but philosophical maturity, was written by Star Trek creators with intentional parallels to modern human society—particularly its historical progression toward cultural enlightenment, reason and tolerance interrupted by extreme bouts of cultural regression, irrationalism and fanatical violence.

Depiction
The character of Surak in the Star Trek television series backstory, after up-ending the Vulcan people's violent tribalism with a philosophy of communal commitment to reason and logic, dies in the 4th century AD (based upon Earth's calendar, approximately 1,800 years before the events of the Star Trek: Enterprise episode "Awakening"), apparently of radiation poisoning caused by a nuclear attack that devastates Vulcan. It's mentioned that his death was shortly before the final battle between the Vulcans and their enemies. His spirit, or katra, is transferred into a crystalline urn which remains entombed and undisturbed until its rediscovery after two millennia by a Vulcan character, Syrran, in the 22nd century. Syrran places Surak's katra within his own mind, which leads Syrran to create a group called Syrranites dedicated to returning Vulcan civilization to the true teachings of Surak. A decade later, in 2154 prior to the outbreak of impending Vulcan civil war, Syrran is killed while escorting the characters of Captain Jonathan Archer and T'Pol to his group's headquarters in the Vulcan Forge. Before dying of his wounds, Syrran places Surak's katra into Archer's mind.

Experiencing a hallucination (or vision), Archer finds himself conversing with Surak within his own mind. Together, they witness the nuclear explosion that had occurred on Vulcan 1,800 years earlier, causing Surak's apparent death by radiation poisoning. It is implied that those elements responsible for setting off the nuclear attack are a splinter group of Vulcans that reject Surak's philosophy and go on to form the Romulan Empire.

A subsequent attempt to transfer Surak's katra to Syrran's second-in-command, T'Pau, fails when Surak chooses to remain merged with Archer. Once again conversing with Archer inside his mind and appearing radiation burned, Surak instructs him to recover an artifact called the Kir'Shara, which Surak claims will unite the warring factions on latter-day Vulcan. It is unscripted whether Surak himself creates this artifact, or whether it is later created by other Vulcans who carry his katra. The Kir'Shara is a holographic projector of the philosopher's original, long-lost testament—capable of restoring Vulcan society to the "true path" of non-violence and logic. Archer later warns his companions that the Vulcan High Command intends to attack the Andorians, having learned this from Surak who he believes discovered it from some of Syrran's memories that got transferred over as well. Archer and T'Pau succeed in taking the artifact to the corrupt Vulcan High Command in the Star Trek: Enterprise episode "Kir'Shara", resulting in its overthrow. Surak's katra is subsequently transferred into the mind of an elderly Vulcan priest; what becomes of his katra afterwards in the Star Trek backstory is, as yet, unscripted.

Star Trek author Diane Duane explored Surak's backstory from the character's own perspective, in the novel Spock's World – which depicts Surak's initial awakening and dissemination of his philosophy after leaving his job as a computer programmer in response to a nuclear explosion from a war between mining conglomerates that spreads to T'Khut, Vulcan's "moon" (in reality, Vulcan's smaller binary planet). In the character's depicted internal struggle, Surak conquers his own xenophobia, becomes "awake" to the horrors of war, and develops the pluralistic rationalist philosophy of IDIC ("Infinite Diversity in Infinite Combinations") plus logic that ultimately brings peace to Vulcan.

The character names of many latter-day Vulcan males begin with "S" and end in "k", perhaps to honor Surak, though some Vulcan character names do not fit this formula (e.g. Tuvok).

A character representing a physical re-creation of the "historical Surak" in his youthful maturity—fashioned by advanced alien technology from telepathically-recorded recollections and expectations held by Spock, appears in the original Star Trek series episode "The Savage Curtain", and is portrayed by actor Barry Atwater. The vision of a more elderly Surak appearing in the mind of the character of Captain Jonathan Archer is portrayed by actor Bruce Gray.

The only specific mention of the character of Surak in the 24th century period of the Star Trek saga is in the Star Trek: Deep Space Nine episode "In the Cards", where the character of the Ferengi trader, Quark, hawks a bracelet "from the time of Surak" and in the 23rd century Prime Universe story line wherein Surak is mentioned along with predominantly historical figures in Star Trek II: The Wrath of Khan when the son of Adm. James T. Kirk, Dr. David Marcus, tells his mother, Dr. Carol Marcus, that her name will be mentioned along with other famous scientific individuals such as "Cochran, Einstein and Surak" in reference to her designing and building the Genesis Device.

Cultural impact
The fictional Surak's philosophy of rationalism with emotional mastery and its role as a cornerstone of Vulcan and Starfleet mythos has contributed a distinct philosophical component to the broader cultural influence of Star Trek. Similar to the anecdotal testimonies that Star Trek has inspired many of its viewers to become scientists or engineers,  other viewers have adopted Starfleet- or Surak-inspired personal philosophies and lifestyles   and founded fan-based (such as STARFLEET International) or "IDIC plus logic" philosophy-inspired "pluralistic rationalist"  organizations.

title: Surak


text:
Sick building syndrome

Sick building syndrome (SBS) is a condition in which people develop symptoms of illness or become infected with chronic disease from the building in which they work or reside. In the scientific literature, SBS is also known as Building Related Illness (BRI) or Building Related Symptoms (BRS) or Idiopathic Environmental Intolerance (IEI).

The main identifying observation is an increased incidence of complaints of symptoms such as headache, eye, nose, and throat irritation, fatigue, dizziness, and nausea. The 1989 Oxford English Dictionary defines SBS in that way. The World Health Organization created a 484-page tome on indoor air quality back in 1984 when SBS was attributed only to non-organic causes, and suggested that the book might form a basis for legislation or litigation.

The outbreaks may or may not be a direct result of inadequate or inappropriate cleaning methods. SBS has also been used to describe staff concerns in post-war buildings with misplanned building aerodynamics, defects in the construction materials or assembly process and-or inadequate maintenance. Certain symptoms tend to increase in severity with the time people spend in the building; often improving over time or even disappearing when people are away from the building. SBS is also used interchangeably with "building-related symptoms", which orients the name of the condition around patients' symptoms rather than a "sick" building.

Attempts have been made to connect sick building syndrome to various causes, such as contaminants produced by outgassing of some types of building materials, volatile organic compounds (VOC), improper exhaust ventilation of ozone (byproduct of some office machinery), light industrial chemicals used within, or lack of adequate fresh-air intake/air filtration (see minimum efficiency reporting value). Sick building syndrome has also been attributed to heating, ventilation, and air conditioning (HVAC) systems. However, there have been inconsistent findings on whether air conditioning systems result in SBS or not.

Signs and symptoms
Human exposure to aerosols has been documented to give rise to a variety of adverse health effects. Building occupants complain of symptoms such as sensory irritation of the eyes, nose, or throat; neurotoxic or general health problems; skin irritation; nonspecific hypersensitivity reactions; infectious diseases; and odor and taste sensations. Exposure to poor lighting conditions has led to general malaise.

Extrinsic allergic alveolitis has been associated with the presence of fungi and bacteria in the moist air of residential houses and commercial offices. A study in 2017 correlated several inflammatory diseases of the respiration tract with objective evidence of damp-caused damage in homes.

The WHO has classified the reported symptoms into broad categories, including: mucous membrane irritation (eye, nose, and throat irritation), neurotoxic effects (headaches, fatigue, and irritability), asthma and asthma-like symptoms (chest tightness and wheezing), skin dryness and irritation, gastrointestinal complaints and more.

Several sick occupants may report individual symptoms which do not appear to be connected. The key to discovery is the increased incidence of illnesses in general with onset or exacerbation within a fairly close time frame – usually within a period of weeks. In most cases, SBS symptoms will be relieved soon after the occupants leave the particular room or zone. However, there can be lingering effects of various neurotoxins, which may not clear up when the occupant leaves the building. In some cases – particularly in sensitive individuals – there can be long-term health effects.

Cause
ASHRAE has recognized that polluted urban air, designated within the United States Environmental Protection Agency (EPA)'s air quality ratings as unacceptable, requires the installation of treatment such as filtration for which the HVAC practitioners generally apply carbon-impregnated filters and their likes. Different toxins will aggravate the human body in different ways. Some people are more allergic to mold, while others are highly sensitive to dust. Inadequate ventilation will exaggerate small problems (such as deteriorating fiberglass insulation or cooking fumes) into a much more serious indoor air quality problem.

Common products such as paint, insulation, rigid foam, particle board, plywood, duct liners, exhaust fumes and other chemical contaminants from indoor or outdoor sources, and biological contaminants can be trapped inside by the HVAC AC system. As this air is recycled using fan coils the overall oxygenation ratio drops and becomes harmful. When combined with other stress factors such as traffic noise, poor lighting, inhabitants of buildings located in a polluted urban area can quickly become ill as their immune system is overwhelmed.

Certain VOCs, considered toxic chemical contaminants to humans, are used as adhesives in all common building construction products. These aromatic carbon rings / VOCs can cause acute and chronic health effects on the occupants of a building, including cancer, paralysis, lung failure, and others. Bacterial spores, fungal spores, mold spores, pollen, and viruses are types of biological contaminants and can all cause allergic reactions or illness described as SBS. In addition, pollution from outdoors, such as motor vehicle exhaust, can infiltrate into poorly designed buildings and contribute to poor indoor air quality, high ppm of CO and CO2. Adult SBS symptoms were associated with a history of allergic rhinitis, eczema and asthma.

A 2015 study concerning the association of SBS and indoor air pollutants in office buildings in Iran found that, as carbon dioxide levels increase in a building, symptoms like nausea, headaches, nasal irritation, dyspnea, and throat dryness have also been shown to increase. Certain work conditions have been found to be correlated with specific symptoms. For example, higher light intensity was significantly related to skin dryness, eye pain, and malaise. Higher temperature has also been found to correlate with symptoms such as sneezing, skin redness, itchy eyes and headache, while lower relative humidity has been associated with sneezing, skin redness, and pain of the eyes.

In 1973, in response to the oil crisis and conservation concerns, ASHRAE Standards 62-73 and 62-81 reduced required ventilation from 10 cuft/min per person to 5 cuft/min per person, but this was found to be a contributing factor to sick building syndrome. As of the 2016 revision, ASHRAE ventilation standards call for 5 to 10 cubic feet per minute of ventilation per occupant (depending on the occupancy type) in addition to ventilation based on the zone floor area delivered to the breathing zone.

Workplace
Excessive work stress or dissatisfaction, poor interpersonal relationships and poor communication are often seen to be associated with SBS, recent studies show that a combination of environmental sensitivity and stress can greatly contribute to sick building syndrome.

Greater effects were found with features of the psycho-social work environment including high job demands and low support. The report concluded that the physical environment of office buildings appears to be less important than features of the psycho-social work environment in explaining differences in the prevalence of symptoms. However, there is still a relationship between sick building syndrome and symptoms of workers regardless of workplace stress.

Specific work-related stressors are related with specific SBS symptoms. Workload and work conflict are significantly associated with general symptoms (headache, abnormal tiredness, sensation of cold or nausea). While crowded workspaces and low work satisfaction are associated with upper respiratory symptoms. Work productivity has been associated with ventilation rates, a contributing factor to SBS, and there's a significant increase in production as ventilation rates increase, by 1.7% for every two-fold increase of ventilation rate. Printer effluent, released into the office air as ultra-fine particles (UFPs) as toner is burned during the printing process, may lead to certain SBS symptoms. Printer effluent may contain a variety of toxins to which a subset of office workers are sensitive, triggering SBS symptoms.

Specific careers are also associated with specific SBS symptoms. Transport, communication, healthcare, and social workers have highest prevalence of general symptoms. Skin symptoms such as eczema, itching, and rashes on hands and face are associated with technical work. Forestry, agriculture, and sales workers have the lowest rates of sick building syndrome symptoms.

From the assessment done by Fisk and Mudarri, 21% of asthma cases in the United States were caused by wet environments with mold that exist in all indoor environments, such as schools, office buildings, houses and apartments. Fisk and Berkeley Laboratory colleagues also found that the exposure to the mold increases the chances of respiratory issues by 30 to 50 percent. Additionally, studies showing that health effects with dampness and mold in indoor environments found that increased risk of adverse health effects occurs with dampness or visible mold environments.

Milton et al. determined the cost of sick leave specific for one business was an estimated $480 per employee, and about five days of sick leave per year could be attributed to low ventilation rates. When comparing low ventilation rate areas of the building to higher ventilation rate areas, the relative risk of short-term sick leave was 1.53 times greater in the low ventilation areas.

Home
Sick building syndrome can also occur due to factors of the home. Laminate flooring can cause more exposure to chemicals and more resulting SBS symptoms compared to stone, tile, and cement flooring. Recent redecorating and new furnishings within the last year were also found to be associated with increased symptoms, along with dampness and related factors, having pets, and the presence of cockroaches. The presence of mosquitoes was also a factor related to more symptoms, though it is unclear whether it was due to the presence of mosquitoes or the use of repellents.

Mold
Some studies have found that sick building syndrome may be associated with indoor mold or mycotoxin contamination. However, the attribution of sick building syndrome to mold is controversial and supported by little evidence.

Indoor temperature
Indoor temperature under 18 °C (64 °F) has been shown to be associated with increased respiratory and cardiovascular diseases, increased blood levels, and increased hospitalization.

Diagnosis
While sick building syndrome (SBS) encompasses a multitude of non-specific symptoms, building-related illness (BRI) comprises specific, diagnosable symptoms caused by certain agents (chemicals, bacteria, fungi, etc.). These can typically be identified, measured, and quantified. There are usually four causal agents in BRi: immunologic, infectious, toxic, and irritant. For instance, Legionnaire's disease, usually caused by Legionella pneumophila, involves a specific organism which could be ascertained through clinical findings as the source of contamination within a building.

Prevention

 * Reduction of time spent in the building
 * If living in the building, moving to a new place
 * Fixing any deteriorated paint or concrete deterioration
 * Regular inspections to indicate for presence of mold or other toxins
 * Adequate maintenance of all building mechanical systems
 * Toxin-absorbing plants, such as sansevieria
 * Roof shingle non-pressure cleaning for removal of algae, mold, and Gloeocapsa magma
 * Using ozone to eliminate the many sources, such as VOCs, molds, mildews, bacteria, viruses, and even odors. However, numerous studies identify high-ozone shock treatment as ineffective despite commercial popularity and popular belief.
 * Replacement of water-stained ceiling tiles and carpeting
 * Only using paints, adhesives, solvents, and pesticides in well-ventilated areas or only using these pollutant sources during periods of non-occupancy
 * Increasing the number of air exchanges; the American Society of Heating, Refrigeration and Air-Conditioning Engineers recommend a minimum of 8.4 air exchanges per 24-hour period
 * Increased ventilation rates that are above the minimum guidelines
 * Proper and frequent maintenance of HVAC systems
 * UV-C light in the HVAC plenum
 * Installation of HVAC air cleaning systems or devices to remove VOCs and bioeffluents (people odors)
 * Central vacuums that completely remove all particles from the house including the ultrafine particles (UFPs) which are less than 0.1 μm
 * Regular vacuuming with a HEPA filter vacuum cleaner to collect and retain 99.97% of particles down to and including 0.3 micrometers
 * Placing bedding in sunshine, which is related to a study done in a high-humidity area where damp bedding was common and associated with SBS
 * Lighting in the workplace should be designed to give individuals control, and be natural when possible
 * Relocating office printers outside the air conditioning boundary, perhaps to another building
 * Replacing current office printers with lower emission rate printers
 * Identification and removal of products containing harmful ingredients

Management
SBS, as a non-specific blanket term, does not have any specific cause or cure. Any known cure would be associated with the specific eventual disease that was cause by exposure to known contaminants. In all cases, alleviation consists of removing the affected person from the building associated. BRI, on the other hand, utilizes treatment appropriate for the contaminant identified within the building (e.g., antibiotics for Legionnaire's disease).

Improving the indoor air quality (IAQ) of a particular building can attenuate, or even eliminate, the continued exposure to toxins. However, a Cochrane review of 12 mold and dampness remediation studies in private homes, workplaces and schools by two independent authors were deemed to be very low to moderate quality of evidence in reducing adult asthma symptoms and results were inconsistent among children. For the individual, the recovery may be a process involved with targeting the acute symptoms of a specific illness, as in the case of mold toxins. Treating various building-related illnesses is vital to the overall understanding of SBS. Careful analysis by certified building professionals and physicians can help to identify the exact cause of the BRI, and help to illustrate a causal path to infection. With this knowledge one can, theoretically, remediate a building of contaminants and rebuild the structure with new materials. Office BRI may more likely than not be explained by three events: "Wide range in the threshold of response in any population (susceptibility), a spectrum of response to any given agent, or variability in exposure within large office buildings."

Isolating any one of the three aspects of office BRI can be a great challenge, which is why those who find themselves with BRI should take three steps, history, examinations, and interventions. History describes the action of continually monitoring and recording the health of workers experiencing BRI, as well as obtaining records of previous building alterations or related activity. Examinations go hand in hand with monitoring employee health. This step is done by physically examining the entire workspace and evaluating possible threats to health status among employees. Interventions follow accordingly based on the results of the Examination and History report.

Epidemiology
Some studies have found that women have higher reports of SBS symptoms than men. It is not entirely clear, however, if this is due to biological, social, or occupational factors.

A 2001 study published in the Journal Indoor Air, gathered 1464 office-working participants to increase the scientific understanding of gender differences under the Sick Building Syndrome phenomenon. Using questionnaires, ergonomic investigations, building evaluations, as well as physical, biological, and chemical variables, the investigators obtained results that compare with past studies of SBS and gender. The study team found that across most test variables, prevalence rates were different in most areas, but there was also a deep stratification of working conditions between genders as well. For example, men's workplaces tend to be significantly larger and have all-around better job characteristics. Secondly, there was a noticeable difference in reporting rates, specifically that women have higher rates of reporting roughly 20% higher than men. This information was similar to that found in previous studies, thus indicating a potential difference in willingness to report.

There might be a gender difference in reporting rates of sick building syndrome, because women tend to report more symptoms than men do. Along with this, some studies have found that women have a more responsive immune system and are more prone to mucosal dryness and facial erythema. Also, women are alleged by some to be more exposed to indoor environmental factors because they have a greater tendency to have clerical jobs, wherein they are exposed to unique office equipment and materials (example: blueprint machines, toner-based printers), whereas men often have jobs based outside of offices.

History
In the late 1970s, it was noted that nonspecific symptoms were reported by tenants in newly constructed homes, offices, and nurseries. In media it was called "office illness". The term "sick building syndrome" was coined by the WHO in 1986, when they also estimated that 10–30% of newly built office buildings in the West had indoor air problems. Early Danish and British studies reported symptoms.

Poor indoor environments attracted attention. The Swedish allergy study (SOU 1989:76) designated "sick building" as a cause of the allergy epidemic as was feared. In the 1990s, therefore, extensive research into "sick building" was carried out. Various physical and chemical factors in the buildings were examined on a broad front.

The problem was highlighted increasingly in media and was described as a "ticking time bomb". Many studies were performed in individual buildings.

In the 1990s "sick buildings" were contrasted against "healthy buildings". The chemical contents of building materials were highlighted. Many building material manufacturers were actively working to gain control of the chemical content and to replace criticized additives. The ventilation industry advocated above all more well-functioning ventilation. Others perceived ecological construction, natural materials, and simple techniques as a solution.

At the end of the 1990s came an increased distrust of the concept of "sick building". A dissertation at the Karolinska Institute in Stockholm 1999 questioned the methodology of previous research, and a Danish study from 2005 showed these flaws experimentally. It was suggested that sick building syndrome was not really a coherent syndrome and was not a disease to be individually diagnosed, but a collection of as many as a dozen semi-related diseases. In 2006 the Swedish National Board of Health and Welfare recommended in the medical journal Läkartidningen that "sick building syndrome" should not be used as a clinical diagnosis. Thereafter, it has become increasingly less common to use terms such as sick buildings and sick building syndrome in research. However, the concept remains alive in popular culture and is used to designate the set of symptoms related to poor home or work environment engineering. Sick building is therefore an expression used especially in the context of workplace health.

Sick building syndrome made a rapid journey from media to courtroom where professional engineers and architects became named defendants and were represented by their respective professional practice insurers. Proceedings invariably relied on expert witnesses, medical and technical experts along with building managers, contractors and manufacturers of finishes and furnishings, testifying as to cause and effect. Most of these actions resulted in sealed settlement agreements, none of these being dramatic. The insurers needed a defense based upon Standards of Professional Practice to meet a court decision that declared that in a modern, essentially sealed building, the HVAC systems must produce breathing air for suitable human consumption. ASHRAE (American Society of Heating, Refrigeration and Air Conditioning Engineers, currently with over 50,000 international members) undertook the task of codifying its indoor air quality (IAQ) standard.

ASHRAE empirical research determined that "acceptability" was a function of outdoor (fresh air) ventilation rate and used carbon dioxide as an accurate measurement of occupant presence and activity. Building odors and contaminants would be suitably controlled by this dilution methodology. ASHRAE codified a level of 1,000 ppm of carbon dioxide and specified the use of widely available sense-and-control equipment to assure compliance. The 1989 issue of ASHRAE 62.1-1989 published the whys and wherefores and overrode the 1981 requirements that were aimed at a ventilation level of 5,000 ppm of carbon dioxide (the OSHA workplace limit), federally set to minimize HVAC system energy consumption. This apparently ended the SBS epidemic.

Over time, building materials changed with respect to emissions potential. Smoking vanished and dramatic improvements in ambient air quality, coupled with code compliant ventilation and maintenance, per ASHRAE standards have all contributed to the acceptability of the indoor air environment.

title: Sick building syndrome