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10482. Za všechno mohou elektrony a reciproká mříž

Creator:
Valvoda, Václav
Format:
print
Type:
model:article and TEXT
Subject:
fyzika, physics, 6, and 53
Language:
Czech and English
Description:
Krátké zamyšlení nad souvislostí struktury krystalů a jejich vlastnostmi a nad fyzikálními a geometrickými principy difrakce rentgenového záření., The article contains a brief contemplation on the relationship between the structure and properties of crystals and on physical and geometrical principles of X-ray diffraction., Václav Valvoda., and Obsahuje seznam literatury
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

10484. Zákony zachování v moderních variačních teoriích: odkaz Emmy Noetherové

Creator:
Czudková, Lenka, Musilová, Jana, and Strouhalová, Jitka
Format:
print, bez média, and svazek
Type:
model:article and TEXT
Subject:
Noether, Emmy, 1882-1935, variační metody, matematika, variational methods, mathematics, 6, and 53
Language:
Czech and English
Description:
Otázku, kde se berou zákony zachování hybnosti, momentu hybnosti, mechanické energie a dalších veličin, lze v rámci klasické mechaniky či teorie pole zodpovědět různými způsoby. Principiálně však zachovávající se veličiny souvisejí s operacemi symetrie daného problému. Tuto souvislost odhaluje pro případ teorií řídících se variačním principem teorém Emmy Noetherové z roku 1918, odvozený klasickým "souřadnicovým" způsobem užívajícím variací, tehdy ve variačním počtu obvyklým. Propracovaný moderní geometrický aparát fibrovaných variet a diferenciálních forem "kopírujících" jejich struktura je mnohem účinnějším prostředkem pro formulaci jak variačních teorií samotných, tak i jejich důsledků právě typu teorému Noetherové. Podstatu geometrického přístupu lze objasnit již na nejjednodušším případu - jednorozměrném pohybu klasické částice v mechanice., The question of the origin of conservation laws for the momentum, angular momentum, mechanical energy and other quantities in classical mechanics and classical field theories can be answered by various ways. Nevertheless, in principle the conserved quantities are connected with the symmetry of a problem under consideration. For variational theories such a connection was disclosed by the Emmy Noether theorem derived in 1918 by a classical "coordinate" procedure using variations, which was typical for the former calculus of variations. The elaborate modern geometrical formalism of fibred manifolds and differential forms adapted to their fibred structure is a much more effective tool not only for variational theories themselves but also for their consequences as the Noether theorem. The merit of the geometrical approach can be explained by the simplest example - a one-dimensional motion of a classical mechanical particle., Lenka Czudková, Jana Musilová, Jitka Strouhalová., and Obsahuje bibliografii
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

10487. Zastavování světla

Creator:
Dvořák, Vladimír
Format:
print, bez média, and svazek
Type:
model:article and TEXT
Subject:
fyzika, optika, světlo, physics, optics, light, 6, and 53
Language:
Czech and English
Description:
Nedávno se třem skupinám ve Spojených státech podařilo zpomalit světelný puls na neuvěřitelných několik metrů za vteřinu a posléze jej dokonce na okamžik zastavit. Pokusy byly prováděny ve třech různých prostředích: v Boseově-Einsteinově kondenzátu sodíkových atomů, v parách atomů rubidia a v krystalu křemičitanu yttritého, dopovaném praseodymem. K zastavování světla se využívá jevu elektromagneticky indukované průhlednosti, kdy za určitých rezonančních podmínek jeden, tzv. kontrolní laserový puls vytváří společně s druhým zkušebním pulsem průhledné prostředí s obrovskou disperzí indexu lomu. Ta je pak vlastní příčinou radikálního snížení grupové rychlosti zkušebního světelného pulsu, který s koherentními kvantovými stavy atomů vytváří "propletený" stav, tzv. tmavý polariton, šířící se beze ztrát prostředím. Rychlost tmavého polaritonu je možné ovládat kontrolním pulsem. Polariton lze zastavit, přičemž je celý zkušební puls převeden do koherentních kvantových stavů atomů a posléze je možné zkušební puls v původní podobě obnovit. V tomto přehledu jsou odvozeny rovnice, které tyto jevy popisují, jednotlivé pokusy jsou podrobně diskutovány a jsou zmíněna možná využití zastavování světla., Vladimír Dvořák., and Obsahuje bibliografie
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

10488. Žďarky-Pstrążna dome: a strike-slip fault-related structure at the eastern termination of the Poříčí-Hronov Fault Zone (Sudetes)

Creator:
Wojewoda, Jurand
Format:
print, bez média, and svazek
Type:
article, články, model:article, and TEXT
Subject:
Geologie. Meteorologie. Klimatologie, svrchní křída, geodynamika, upper cretaceous, geodynamics, Krkonošsko-jesenická soustava (pohoří), Sudety mountains, strike-sip fult, 7, and 551
Language:
English
Description:
The trans-border area of the Sudetes between Žďarky and Pstrążna has attracted Prussian/German, Austrian, Czech and Polish geologists since the middle of the 19th century. The history of mapping of this area reflects the scientific development of geological centres in Berlin, Vienna, Prague and Wrocław. This paper presents a description of the oldest geological maps of Lower Silesia in the context of changing knowledge on the Carboniferous and Cretaceous stratigraphy and on the tectonics of the region. On the basis of DEM and field studies the author presents his own geological map of the area of the Pstrążna Elevation together with a description of the local structural geology. A regional structural model is suggested, that explains all the local elevations as having developed in response to a dextral strike-slip activity of the Žďarky-Jakubowice Fault during late Tertiary to Recent times, at an eastern extension of the Poříčí-Hronov Fault Zone., Jurand Wojewoda., and Obsahuje bibliografii
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

10489. Zdeněk Mlynář and the search for socialist opposition: from an active politician to a dissident to editorial work in exile

Creator:
Catalano, Alessandro
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
Prague spring, dissidents, and Zdeněk Mlynář
Language:
English
Description:
The presented essay was originally published as ''Il samizdat tra dialogo e monologo: Le attività editoriali di Zdeněk Mlynář e la scelta degli interlocutori'' in the Italian online journal eSamizdat: Rivista di culture dei paesi slavi (2010-11, pp. 261-80). This double issue is based on papers given at the conference ''Samizdat between Memory and Utopia: Independent Culture in Czechoslovakia and the Soviet Union in the Second Half of the Twentieth Century,'' which was held at Padua University in late May and early June 2011, and is freely accessible on the periodical website (http://www.esamizdat.it/rivista/2010-2011/index.htm). For its publication in Soudobé dějiny, the author has considerably expanded his essay, particularly after doing research in the Mlynář Papers deposited in the National Archive, Prague. The author concentrates mainly on the research and publishing activities of the politician and political scientist Zdeněk Mlynář (1930-1997) while he was in exile, which he puts into a detailed chronology of his career as a public fi gure. He asks and seeks to answer the general question whether the milieu of samizdat and independent publishing, which developed in Czechoslovakia in the 1970s and 1980s, did or did not leave deep traces also in the structures of the various political activities of those who criticised the state-sanctioned arts and sciences of ''normalisation'' Czechoslovakia. The author points out that Mlynář has today been largely ousted from Czech historical memory, even though he was amongst the leading opponents of the regime after its collapse, and tried to regain a place in Czechoslovak politics. The author recalls Mlynář’s becoming a member of the Czechoslovak Communist Party, his law studies in Moscow in the fi rst half of the 1950s, where he formed a lasting friendship with his fellow-student Mikhail Gorbachev (b. 1931), and last but not least Mlynář as an expert researching the prospects of the socialist political system in the 1960s. He then concentrates on Mlynář’s work during the Prague Spring of 1968, when he became a member of the reformist leadership of the CommunistParty on the side of Alexander Dubček (1921-1992). After the August intervention by the armies of fi ve Warsaw Pact states, Mlynář gradually became disillusioned with the possibilities of continuing reform, and he resigned from the Party leadership. In the early 1970s, he found employment in the Department of Entomology of the National Museum, Prague, and avoided political life completely. Nevertheless, he gradually started to take part in debates with other reformists expelled from the Party about the possibilities of infl uencing developments in Czechoslovakia with the help of left-wing parties in Western Europe. The author discusses Mlynář’s analyses of the situation at the time, the development of his views, and his integration into the nascent dissident movement, which appeared after the founding of Charter 77. A few months later, in June 1977 to be precise, Mlynář emigrated to Austria as a consequence of a smear campaign against the Chartists. The author focuses on Mlynář’s close work amongst Czech exiles, particularly with the increasingly diverse Listy group, which was established by Jiří Pelikán (1923-1999). The group in question was centred on the exile periodical of the same title, which was published in Rome and formed the core of Czechoslovak socialist opposition in exile. In addition, the author focuses on the efforts of Mlynář and his colleagues to win support among Western left-wing circles, particularly in relation to the Italian Communists and Socialists and later the West German Social Democrats. He also takes into account Mlynář’s political essays, which met with a considerable response amongst the public of Western Europe, and the clear shift in opinion from the initial model of a political system with Communist Party hegemony to political pluralism. In this context, the author then gives a comprehensive account of two large research and publishing projects coordinated by Mlynář. The fi rst project, from 1979 to 1982, was entitled ''Experiences of the Prague Spring of 1968''; its participants were almost exclusively Czech sociologists, historians, economists, jurists, and other specialists in exile. The project resulted in almost 30 mimeographed volumes in three language versions (mostly Italian, French, and English), which were distributed by several hundred carefully selected left-wing individuals and institutions in the West, and it culminated in a congress held in Paris. According to the author, this little known project represents one of the most profound and essentially never-published refl ections on the origins, development, and failure of the Prague Spring. The second project, entitled ''Crises in Soviet-type Systems,'' ran from 1982 to the late 1980s, and presented the perspectives of authors from a wider range of central European countries. It resulted in 16 works by Czech, Polish, Hungarian, and East German authors, published by the leading Czech exile publishing house, Index, as small paperback editions in English, French, and indeed German. The number of its subscribers grew to about 2,000. Part of the project was presenting papers at conferences and other international forums. Both of the projects in question, according to the author, demonstrate Mlynář and his colleagues’ persistent orientation to exclusive circles of the political Left in the West, whom, in their efforts to change things in Czechoslovakia, they preferred to the dissidents still in Czechoslovakia.
Rights:
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10490. Ženy ve fyzice: pár slov o mezinárodní "fyzikální konferenci bez fyziky"

Creator:
Heyrovská, Raji, Kodymová, Jarmila, Krupková, Olga, and Musilová, Jana
Format:
print, bez média, and svazek
Type:
model:article and TEXT
Subject:
fyzika, konference, fyzičky, physics, conferences, women physicists, 6, and 53
Language:
Czech and English
Description:
Raji Heyrovská, Jarmila Kodymová, Olga Krupková, Jana Musilová. and Obsahuje bibliografii
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

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