475 research outputs found

    Dehydration and ionic conductance quantization in nanopores

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    There has been tremendous experimental progress in the last decade in identifying the structure and function of biological pores (ion channels) and fabricating synthetic pores. Despite this progress, many questions still remain about the mechanisms and universal features of ionic transport in these systems. In this paper, we examine the use of nanopores to probe ion transport and to construct functional nanoscale devices. Specifically, we focus on the newly predicted phenomenon of quantized ionic conductance in nanopores as a function of the effective pore radius - a prediction that yields a particularly transparent way to probe the contribution of dehydration to ionic transport. We study the role of ionic species in the formation of hydration layers inside and outside of pores. We find that the ion type plays only a minor role in the radial positions of the predicted steps in the ion conductance. However, ions with higher valency form stronger hydration shells, and thus, provide even more pronounced, and therefore, more easily detected, drops in the ionic current. Measuring this phenomenon directly, or from the resulting noise, with synthetic nanopores would provide evidence of the deviation from macroscopic (continuum) dielectric behavior due to microscopic features at the nanoscale and may shed light on the behavior of ions in more complex biological channels.Comment: 13 pages, 10 figure

    A Finite-Size Scaling Study of a Model of Globular Proteins

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    Grand canonical Monte Carlo simulations are used to explore the metastable fluid-fluid coexistence curve of the modified Lennard-Jones model of globular proteins of ten Wolde and Frenkel (Science, v277, 1975 (1997)). Using both mixed-field finite-size scaling and histogram reweighting methods, the joint distribution of density and energy fluctuations is analyzed at coexistence to accurately determine the critical-point parameters. The subcritical coexistence region is explored using the recently developed hyper-parallel tempering Monte Carlo simulation method along with histogram reweighting to obtain the density distributions. The phase diagram for the metastable fluid-fluid coexistence curve is calculated in close proximity to the critical point, a region previously unattained by simulation.Comment: 17 pages, 10 figures, 2 Table

    Electron-beam modification of coating-aluminum substrate systems

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    Multiphase surface alloys with improved strength and tribological characteristics have been synthesized by exposing coating/A7 substrate systems to a pulsed electron beam. Optimum modes of electron-ion-plasma treatment of commercially pure aluminum have been found at which the wear resistance and hardness of the surface layer were observed to increase by a factor of about 7.5 and up to 18, respectively

    Influence of Phase Diffuser Dynamics on Scintillations of Laser Radiation in Earth Atmosphere: Long-Distance Propagation

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    The effect of a random phase diffuser on fluctuations of laser light (scintillations) is studied. Not only spatial but also temporal phase variations introduced by the phase diffuser are analyzed. The explicit dependence of the scintillation index on finite-time phase variations is obtained for long propagation paths. It is shown that for large amplitudes of phase fluctuations, a finite-time effect decreases the ability of phase diffuser to suppress the scintillations.Comment: 15 pages, 4 figure

    Saint-Petersburg Academic Fine Art in the Space of Contemporary Creative Industries

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    Π’ послСдниС дСсятилСтия Π² ΠŸΠ΅Ρ‚Π΅Ρ€Π±ΡƒΡ€Π³Π΅ Π°ΠΊΡ‚ΠΈΠ²Π½ΠΎ Ρ€Π°Π·Π²ΠΈΠ²Π°ΡŽΡ‚ΡΡ ΠΊΡ€Π΅Π°Ρ‚ΠΈΠ²Π½Ρ‹Π΅ индустрии, Ρ„ΠΎΡ€ΠΌΠΈΡ€ΡƒΡŽΡ‚ΡΡ всС Π½ΠΎΠ²Ρ‹Π΅ ΠΊΡ€Π΅Π°Ρ‚ΠΈΠ²Π½Ρ‹Π΅ пространства, Π½Π°Ρ†Π΅Π»Π΅Π½Π½Ρ‹Π΅ Π½Π° взаимодСйствиС Ρ€Π°Π·Π½Ρ‹Ρ… худоТСствСнных институций ΠΈ Ρ€Π΅ΠΏΡ€Π΅Π·Π΅Π½Ρ‚Π°Ρ†ΠΈΡŽ соврСмСнного искусства. Π’Π°ΠΆΠ½ΠΎ ΠΎΡ†Π΅Π½ΠΈΡ‚ΡŒ, ΠΊΠ°ΠΊΡƒΡŽ Ρ€ΠΎΠ»ΡŒ ΠΈΠ³Ρ€Π°Π΅Ρ‚ ΠΏΡ€ΠΎΡ„Π΅ΡΡΠΈΠΎΠ½Π°Π»ΡŒΠ½ΠΎΠ΅ акадСмичСскоС искусство, прСдставлСнноС Ρ‚Ρ€Π°Π΄ΠΈΡ†ΠΈΠΎΠ½Π½Ρ‹ΠΌΠΈ школами ΠΈ ΠΎΡ‚Π΄Π΅Π»ΡŒΠ½Ρ‹ΠΌΠΈ мастСрами Π² Ρ€Π°Π·Π²ΠΈΡ‚ΠΈΠΈ Π½ΠΎΠ²Ρ‹Ρ… Π°Ρ€Ρ‚-пространств, ΠΏΠΎΡΠ²ΠΈΠ²ΡˆΠΈΡ…ΡΡ Π² Π‘Π΅Π²Π΅Ρ€Π½ΠΎΠΉ столицС. Как соотносится акадСмичСская школа с Π΅Ρ‘ Ρ‚Ρ€Π°Π΄ΠΈΡ†ΠΈΠΎΠ½Π½Ρ‹ΠΌΠΈ устоями с потрСбностями посСтитСлСй Π°Ρ€Ρ‚-пространств, Π² Ρ‡Π΅ΠΌ Ρ€ΠΎΠ»ΡŒ соврСмСнных Ρ…ΡƒΠ΄ΠΎΠΆΠ½ΠΈΠΊΠΎΠ², Π·Π°Π½ΠΈΠΌΠ°ΡŽΡ‰ΠΈΡ…ΡΡ ΠΏΡ€Π΅ΠΎΠ±Ρ€Π°Π·ΠΎΠ²Π°Π½ΠΈΠ΅ΠΌ ΠΊΡƒΠ»ΡŒΡ‚ΡƒΡ€Π½ΠΎΠ³ΠΎ досуга насСлСния ΠŸΠ΅Ρ‚Π΅Ρ€Π±ΡƒΡ€Π³Π°? Π’ ΡΡ‚Π°Ρ‚ΡŒΠ΅ прСдлагаСтся искусствовСдчСский ΠΎΠ±Π·ΠΎΡ€ соврСмСнной ситуации сущСствования акадСмичСского искусства Π² Ρ€Π°ΠΌΠΊΠ°Ρ… пСтСрбургской ΠΊΡ€Π΅Π°Ρ‚ΠΈΠ²Π½ΠΎΠΉ индустрии, ΠΏΡ€Π΅Π΄ΡΡ‚Π°Π²Π»ΡΡŽΡ‰Π΅ΠΉ Ρ€Π°Π·Π»ΠΈΡ‡Π½Ρ‹Π΅ худоТСствСнныС направлСнияБreative industries have been actively developing during the in recent decades in Saint Petersburg more and more new creative spaces aimed at the interaction of various art institutions and representation of contemporary art have been formed. The study tested the role professional academic art, as represented by traditional schools and individual masters in the development of the new art spaces that have appeared in Saint Petersburg. How does the academic school with its traditional ways relate to the needs of visitors of art spaces, what is the role of contemporary artists engaged in the transformation of the cultural leisure time of visitors of creative spaces? The article offers an art history review of the current situation of academic art within St. Petersburg’s creative industries, representing different artistic movement

    Actual Issues of the Russian Academic Art History Methodology

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    Одной ΠΈΠ· ΠΊΡ€ΡƒΠΏΠ½Π΅ΠΉΡˆΠΈΡ… акадСмичСских искусствовСдчСских школ Π² России являСтся пСтСрбургская акадСмичСская искусствовСдчСская школа – ΠΎΠ΄Π½Π° ΠΈΠ· ΡΡ‚Π°Ρ€Π΅ΠΉΡˆΠΈΡ… Π² России. Π•Ρ‘ созданиС ΠΈ Ρ„ΠΎΡ€ΠΌΠΈΡ€ΠΎΠ²Π°Π½ΠΈΠ΅ относится ΠΊ 1930–1940‑м Π³ΠΎΠ΄Π°ΠΌ. Π—Π° врСмя своСго сущСствования ΠΎΠ½Π° Π±Ρ‹Π»Π° связана с Π΄Π΅ΡΡ‚Π΅Π»ΡŒΠ½ΠΎΡΡ‚ΡŒΡŽ ΠΊΡ€ΡƒΠΏΠ½Π΅ΠΉΡˆΠΈΡ… историков ΠΈ Ρ‚Π΅ΠΎΡ€Π΅Ρ‚ΠΈΠΊΠΎΠ² искусства ΠΈ худоТСствСнных ΠΊΡ€ΠΈΡ‚ΠΈΠΊΠΎΠ². Π•Ρ‘ ΠΌΠΎΠΆΠ½ΠΎ ΡΡ‡ΠΈΡ‚Π°Ρ‚ΡŒ ΠΎΠ΄Π½ΠΎΠΉ ΠΈΠ· Π°Π²Ρ‚ΠΎΡ€ΠΈΡ‚Π΅Ρ‚Π½Ρ‹Ρ… школ, ΠΏΡ€Π΅Π΄ΡΡ‚Π°Π²Π»ΡΡŽΡ‰ΠΈΡ… ΠΈΡΠΊΡƒΡΡΡ‚Π²ΠΎΠ²Π΅Π΄Ρ‡Π΅ΡΠΊΡƒΡŽ Π½Π°ΡƒΠΊΡƒ ΠΈ связанных с традициями отСчСствСнной ΠΈ Π·Π°Ρ€ΡƒΠ±Π΅ΠΆΠ½ΠΎΠΉ эссСистики ΠΈ знаточСства. ΠŸΡ€ΠΈ этом слСдуСт ΠΎΡ‚ΠΌΠ΅Ρ‚ΠΈΡ‚ΡŒ Π΅Ρ‘ влияниС Π½Π° отСчСствСнноС искусствознаниС Π² Ρ†Π΅Π»ΠΎΠΌ ΠΈ Π½Π° Π΄Π΅ΡΡ‚Π΅Π»ΡŒΠ½ΠΎΡΡ‚ΡŒ ΠΌΠ½ΠΎΠ³ΠΈΡ… худоТСствСнных институций. Π’ послСдниС дСсятилСтия ΠΎΠ½Π° ΠΏΠ΅Ρ€Π΅ΠΆΠΈΠ²Π°Π΅Ρ‚ ΡΠ΅Ρ€ΡŒΠ΅Π·Π½Ρ‹Π΅ трансформации Π² связи с ΠΎΠ±Ρ‰ΠΈΠΌΠΈ тСндСнциями Π² Π³ΡƒΠΌΠ°Π½ΠΈΡ‚Π°Ρ€Π½Ρ‹Ρ… областях Π½Π°ΡƒΠΊΠΈ. На ΠΏΡ€ΠΈΠΌΠ΅Ρ€Π΅ развития этой ΡˆΠΊΠΎΠ»Ρ‹ ΠΌΠΎΠΆΠ½ΠΎ Ρ€Π°ΡΡΠΌΠΎΡ‚Ρ€Π΅Ρ‚ΡŒ, ΠΊΠ°ΠΊ измСняСтся мСтодология акадСмичСского искусствознания, ΠΊΠΎΡ‚ΠΎΡ€ΠΎΠ΅ испытываСт ΡΠ΅Ρ€ΡŒΠ΅Π·Π½ΠΎΠ΅ влияниС ΠΊΡƒΠ»ΡŒΡ‚ΡƒΡ€ΠΎΠ»ΠΎΠ³ΠΈΠΈ, философии, социологии, лингвистики ΠΈ ΠΌΠ΅ΠΆΠΊΡƒΠ»ΡŒΡ‚ΡƒΡ€Π½ΠΎΠΉ ΠΊΠΎΠΌΠΌΡƒΠ½ΠΈΠΊΠ°Ρ†ΠΈΠΈ. Π˜ΡΠΊΡƒΡΡΡ‚Π²ΠΎΠ·Π½Π°Π½ΠΈΠ΅ испытываСт влияниС худоТСствСнного Ρ€Ρ‹Π½ΠΊΠ° с Π΅Π³ΠΎ Π΄Π΅ΠΌΠΎΠΊΡ€Π°Ρ‚ΠΈΠ·Π°Ρ†ΠΈΠ΅ΠΉ ΠΈ обогащаСтся соврСмСнными ΠΌΠ΅Ρ‚ΠΎΠ΄Π°ΠΌΠΈ исслСдования ΠΈ тСхнологиями. Π’ ΡΡ‚Π°Ρ‚ΡŒΠ΅ рассматриваСтся Π½Π΅ΠΎΠ±Ρ…ΠΎΠ΄ΠΈΠΌΠΎΡΡ‚ΡŒ использования всСго разнообразия соврСмСнной ΠΌΠ΅Ρ‚ΠΎΠ΄ΠΎΠ»ΠΎΠ³ΠΈΠΈ Π³ΡƒΠΌΠ°Π½ΠΈΡ‚Π°Ρ€Π½Ρ‹Ρ… Π½Π°ΡƒΠΊ, Π½ΠΎ Π½Π° основС ΡΠ»ΠΎΠΆΠΈΠ²ΡˆΠΈΡ…ΡΡ Ρ‚Ρ€Π°Π΄ΠΈΡ†ΠΈΠΎΠ½Π½Ρ‹Ρ… ΠΏΠΎΠ΄Ρ…ΠΎΠ΄ΠΎΠ² ΠΊ искусствовСдчСским исслСдованиямOne of the largest academic schools of art history in Russia is the St. Petersburg Academic School of Art History, one of the oldest in Russia. Its creation and formation dates back to the 1930s‑40s. During its existence, it was associated with the activities of major art historians, art theorists and art critics. It can be regarded as one of the authoritative schools representing the science of art and associated with the traditions of domestic and foreign essayism and connoisseurship. At the same time, it should be noted its influence on domestic art history in general and on the activities of many art institutions. In recent decades, it has experienced serious transformations in connection with the general trends in the humanitarian fields of science. On the example of the development of this school it is possible to consider how the methodology of academic art history, which is seriously influenced by cultural studies, philosophy, sociology, linguistics and intercultural communication, is changing. Art history is influenced by the art market with its democratisation and is enriched with modern research methods and technologies. The article considers the necessity of using the whole variety of modern methodology of the humanities, but on the basis of the established traditional approaches to art history researc

    Are We There Yet?: The Development of a Corpus Annotated for Social Acts in Multilingual Online Discourse

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    We present the AAWD and AACD corpora, a collection of discussions drawn from Wikipedia talk pages and small group IRC discussions in English, Russian and Mandarin. Our datasets are annotated with labels capturing two kinds of social acts: alignment moves and authority claims. We describe these social acts, describe our annotation process, highlight challenges we encountered and strategies we employed during annotation, and present some analyses of resulting data set which illustrate the utility of our corpus and identify interactions among social acts and between participant status and social acts and in online discourse

    MΓΆssbauer characterization of microbially mediated iron and manganese ores of variable geological ages

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    A combination of various techniques was applied to investigate the mineralogy of the Neoproterozoic Urucum iron and manganese deposit (Brazil) and Carboniferous and Permian manganese carbonate deposits (China). The examined deposits exhibited signs of microbial mediation from Fe and Mn bacteria and cyanobacteria. The studied samples showed diversity in their composition and particle size. Probes from Urucum deposit revealed that the rocks consist mainly of hematite, showing Mn substitution which reflects the oxidation of Mn on the active surface of Fe-rich biomat. Nanominerals occurring in significant concentration also supported the microbial contribution to the formation of these ores. Representative samples of Neoproterozoic and Permian deposits showed considerable amount of mixed carbonates with variable composition. 57Fe MΓΆssbauer spectroscopy analysis supported by X-ray diffraction and transmission electron microscopy data provided a detailed characterization of Fe-rich mineral phases of the samples, including metal ratio outlooks, particle size dimension and presence and type of impurities. Integrity and high resolution of the methods allowed to determine new features of the samples reflecting important signatures of microbial activity revealing the biogeochemistry of the biomat formation
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