Dynamic Scaling and Two-Dimensional High-Tc Superconductors

There has been ongoing debate over the critical behavior of two-dimensional superconductors; in particular for high Tc superconductors. The conventional view is that a Kosterlitz-Thouless-Berezinskii transition occurs as long as finite size effects do not obscure the transition. However, there have been recent suggestions that a different transition actually occurs which incorporates aspects of both the dynamic scaling theory of Fisher, Fisher, and Huse and the Kosterlitz-Thouless-Berezinskii transition. Of general interest is that this modified transition apparently has a universal dynamic critical exponent. Some have countered that this apparent universal behavior is rooted in a newly proposed finite-size scaling theory; one that also incorporates scaling and conventional two-dimensional theory. To investigate these issues we study DC voltage versus current data of a 12 angstrom thick YBCO film. We find that the newly proposed scaling theories have intrinsic flexibility that is relevant to the analysis of the experiments. In particular, the data scale according to the modified transition for arbitrarily defined critical temperatures between 0 K and 19.5 K, and the temperature range of a successful scaling collapse is related directly to the sensitivity of the measurement. This implies that the apparent universal exponent is due to the intrinsic flexibility rather than some real physical property. To address this intrinsic flexibility, we propose a criterion which would give conclusive evidence for phase transitions in two-dimensional superconductors. We conclude by reviewing results to see if our criterion is satisfied.Comment: 14 page

Das symmetrische Randelementverfahren Numerische Realisierung und Kopplung mit der Finite-Element-Methode zur elastoplastischen Strukturanalyse

Available from TIB Hannover: RR275(1992,5) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

XIX-wieczne dachy krążynowe w Bawarii

Krążynowe kratownice zbudowane z drewnianych elementów po raz pierwszy wprowadził Philibert de l'Orme w 1561 roku. Jednakże wynalazek de l'Orme'a został spopularyzowany dopiero pod koniec XVIII wieku. David Gilly, urzędnik państwowy w pruskiej administracji budowlanej, wypromował ten typ konstrukcji w serii publikacji. Około roku 1800 istniała już znaczna ilość dachów krążynowych, a rozpiętość niektórych z nich wynosiła nawet około 20 m. Podczas gdy historia tych konstrukcji jest dość dobrze znana, to ich dalszy rozwój już znacznie mniej. System ten był krytykowany przez ówczesnych inżynierów, takich jak Paul Joseph Ardant, w latach 40-tych XIX wieku i wysuwano przeciwko niemu argumenty naukowe. Jednakże dach krążynowy był nadal stosowany, aż do końca XIX wieku. Nastąpił nawet pewien renesans tego modelu konstrukcji w ostatnim trzydziestoleciu XIX wieku, spowodowany zapewne publikacjami na temat dachów krążynowych pojawiającymi się w dobrze znanych podręcznikach konstrukcyjnych, takich jak dzieło Gustava Adolfa Breymann'a. My przedstawiamy inne dachy krążynowe, jakie są nadal zachowane w Bawarii. Pochodzą one z okresu pomiędzy rokiem 1824 (zamek Neuburg nad Dunajem) i latami 70-tymi XIX wieku (budowa zbiornika solanki przy rurociągu warzelni soli w Reichenhall-Rosenheim). Znacząca liczba dachów krążynowych została także zachowana wzdłuż kanału łączącego rzeki Dunaj i Men (lata 40-te XIX w.), w domach dla operatorów śluz. Konstrukcje te zostaną zaprezentowane, porównane z wcześniejszymi dachami krążynowymi i skonfrontowane z współczesną literaturą techniczną.Curved roof trusses made up by boards were first introduced by Philibert de l'Orme in 1561. However, de l'Orme's invention did not succeed much until it became popular in the late 18th century. David Gilly, a civil servant in the Prussian administration of buildings, promoted the idea by a series of propagandistic publications. In the years around 1800, a considerable number of curved plank roofs were actually built, ranging up to spans of around 20 m. While the history of these roofs is fairly well known, the later development of the curved plank roof is less known. The system was severely criticized by early engineer such as Paul Joseph Ardant in the 1840ies, and scientific arguments were put forward against it. Nevertheless, curved plank roofs continued to be used until the late 19th century. There was even some Renaissance of the scheme in the last third of the century, probably mainly due to curved plank roofs published in well-known construction manuals such as Gustav Adolf Breymann's. We present different curved plank roofs which are still preserved in Bavaria. They cover the time range between 1824 (Neuburg / Danube, castle) and the 1870ies (brine reservoir building on the Reichenhall-Rosenheim saltworks pipeline). A considerable number of curved plank roofs has also been preserved along the canal between the Danube and the Main (1840ies), in the context of lock attendants' homes. The structures will be presented, compared to earlier curved plank roofs, and put into the context of contemporary technical literature

In vitro treatments for the theront stage of the ciliate protozoan Cryptocaryon irritans

The ciliate protozoan Cryptocaryon irritans Brown, 1951, the ‘marine white spot’, causes one of the most important parasitic fish diseases, with extensive losses every year in mariculture and in the ornamental fish industry. In the present study, we explore the in vitro use of 8 different compounds against the theront (infective) stage of C. irritans; these compounds include extracts of natural products (epigallocatechin gallate (EGCG), L-DOPA, papain), peracetic acid-based compounds (Proxitane® 5:23 and 15% peracetic acid, PAA), quinine-based compounds (quinacrine hydrochloride and chloroquine diphosphate) and hydrogen peroxide. All of these compounds had an effect on theront survival; however, only EGCG caused significant theront mortality when applied in doses ≥50 mg l–1 and over a period of 3 h; papain caused a maximum theront mortality of <50%. We discuss the type of application and potential utility of the compounds tested as part of a management control strategy for C. irritans infections in marine aquaculture and the ornamental fish industry

In vitro treatments for the theront stage of the ciliate protozoan Cryptocaryon irritans

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