495 research outputs found

    Large Broadening of the Superconducting Transition by Fluctuations in a 3D Metal at High Magnetic Fields: The MgB2_{2} case

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    It is shown that the transition to the low temperature superconducting state in a 3D metal at high magnetic field is smeared dramatically by thermal fluctuation of the superconducting order parameter. The resulting superconducting-to-normal crossover occurs in a vortex liquid state which is extended well below the mean-field Hc2H_{c2}. Application to MgB2_{2} yields good quantitative agreement with recently reported data of dHvA oscillation in the superconducting state

    Dissipative dynamics of vortex arrays in anisotropic traps

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    We discuss the dissipative dynamics of vortex arrays in trapped Bose-condensed gases and analyze the lifetime of the vortices as a function of trap anisotropy and the temperature. In particular, we distinguish the two regimes of the dissipative dynamics, depending on the relative strength of the mutual friction between the vortices and the thermal component, and the friction of the thermal particles on the trap anisotropy. We study the effects of heating of the thermal cloud by the escaping vortices on the dynamics of the system.Comment: RevTeX, 8 pages, 3 eps figure

    Economic and political fundamentals for the establishment of the cabinet-owned metallurgical complex in Siberia in the 18th century

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    Economic and political fundamentals for the development of mining and metallurgical production in Siberia in the 18th century are discussed in this paper. The principal type of ownership of large enterprises at that time was serf manufactory, the development of which took place in the conditions of absolutism based on forced labor. Based on a comprehensive set of archive documents, the authors have studied the problem of the transfer under the authority of the Imperial Cabinet of the private Kolyvano-Voskresensk enterprises owned by Demidov, which were established in the 1720s in the south area of Western Siberia. The status change of industrial enterprises is discussed in the context of accidental events (the death of Akinfiy Demidov and the controversy of his heirs) and the consistent processes of development of silver smelting production in the country. The quick development of the metallurgical industry in Russia in the 18th century was caused by a number of domestic and external factors. The Crown extensively attracted private sector capital for the search and development of ore deposits, especially in remote Uralian and Siberian areas. In the 1720s-1740s, the Kolyvano-Voskresensk industrial-territorial complex privately owned by Akinfiy Demidov was established in the south area of Western Siberia. In the middle of the 1740s, the events happened, as a result of which the possessory belonging of the enterprises was changed and these enterprises were transferred under the control and management of the governmental institution – that is, the Imperial Cabinet. Thus, the Kolyvano-Voskresensk plants became the basis of the Cabinet production unit which existed in the 18h-19th centuries.peer-reviewe

    Development of human capital in the system of economic categories of work

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    Today, human capital is one of the main factors in the formation of the knowledge economy, which is the highest stage in the development of an innovative, post-industrial economy. The development of intellectual and spiritual capabilities of a person, as well as the accumulation of human capital, which has a strong influence on the productivity and quality of labor, becomes one of the priorities for the future development of the state. This article discusses the development of human capital in the system of economic categories of labor.peer-reviewe

    An optimal transient growth of small perturbations in thin gaseous discs

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    A thin gaseous disc with an almost keplerian angular velocity profile, bounded by a free surface and rotating around point-mass gravitating object is nearly spectrally stable. Despite that the substantial transient growth of linear perturbations measured by the evolution of their acoustic energy is possible. This fact is demonstrated for the simple model of a non-viscous polytropic thin disc of a finite radial size where the small adiabatic perturbations are considered as a linear combination of neutral modes with a corotational radius located beyond the outer boundary of the flow.Comment: 15 pages, 5 figures, accepted for publication in Ast

    Measurement of the Analyzing Power in pd(pp)n\vec{p}d \to (pp)n \\with a Fast Forward 1S0^1S_0--Diproton

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    A measurement of the analyzing power AyA_y of the pd(pp)+n\vec{p}d \to (pp) + n reaction was carried out at beam energies of 0.5 and 0.8 GeV by detection of a fast forward proton pair of small excitation energy Epp<3E_{pp} < 3 MeV. The kinematically complete experiment made use of the ANKE spectrometer at the internal beam of COSY and a deuterium cluster--jet target. For the first time the SS--wave dominance in the fast diproton is experimentally demonstrated in this reaction. While at Tp=0.8T_p=0.8 GeV the measured analyzing power AyA_y vanishes, it reaches almost unity at Tp=0.5T_p=0.5 GeV for neutrons scattered at θnc.m.=167\theta_n^{c.m.}=167^\circ. The results are compared with a model taking into account one--nucleon exchange, single scattering and Δ\Delta (1232) excitation in the intermediate state. The model describes fairly well the unpolarized cross section obtained earlier by us and the analyzing power at 0.8 GeV, it fails to reproduce the angular dependence of AyA_y at 0.5 GeV.Comment: 4 pages, 4 figures, 1 tabl

    Kinetics of exciton photoluminescence in type-II semiconductor superlattices

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    The exciton decay rate at a rough interface in type-II semiconductor superlattices is investigated. It is shown that the possibility of recombination of indirect excitons at a plane interface essentially affects kinetics of the exciton photoluminescence at a rough interface. This happens because of strong correlation between the exciton recombination at the plane interface and at the roughness. Expressions that relate the parameters of the luminescence kinetics with statistical characteristics of the rough interface are obtained. The mean height and length of roughnesses in GaAs/AlAs superlattices are estimated from the experimental data.Comment: 3 PostScript figure

    A Postulate for Tiger Recovery: The Case of the Caspian Tiger

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    Recent genetic analysis has shown that the extinct Caspian Tiger (P. t. virgata) and the living Amur Tigers (P. t. altaica) of the Russian Far East are actually taxonomically synonymous and that Caspian and Amur groups historically formed a single population, only becoming separated within the last 200 years by human agency. A major conservation implication of this finding is that tigers of Amur stock might be reintroduced, not only back into the Koreas and China as is now proposed, but also through vast areas of Central Asia where the Caspian tiger once lived. However, under the current tiger conservation framework the 12 “Caspian Tiger States” are not fully involved in conservation planning. Equal recognition as “Tiger Range States” should be given to the countries where the Caspian tiger once lived and their involvement in tiger conservation planning encouraged. Today, preliminary ecological surveys show that some sparsely populated areas of Central Asia preserve natural habitat suitable for tigers. In depth assessments should be completed in these and other areas of the Caspian range to evaluate the possibility of tiger reintroductions. Because tigers are a charismatic umbrella species, both ecologically and politically, reintroduction to these landscapes would provide an effective conservation framework for the protection of many species in addition to tigers. And for today’s Amur Tigers this added range will provide a buffer against further loss of genetic diversity, one which will maintain that diversity in the face of selective pressures that can only be experienced in the wild

    Precise measurement of RudsR_{\text{uds}} and RR between 1.84 and 3.72 GeV at the KEDR detector

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    The present work continues a series of the KEDR measurements of the RR value that started in 2010 at the VEPP-4M e+ee^+e^- collider. By combining new data with our previous results in this energy range we measured the values of RudsR_{\text{uds}} and RR at nine center-of-mass energies between 3.08 and 3.72 GeV. The total accuracy is about or better than 2.6%2.6\% at most of energy points with a systematic uncertainty of about 1.9%1.9\%. Together with the previous precise RR measurement at KEDR in the energy range 1.84-3.05 GeV, it constitutes the most detailed high-precision RR measurement near the charmonium production threshold.Comment: arXiv admin note: text overlap with arXiv:1610.02827 and substantial text overlap with arXiv:1510.0266
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