195 research outputs found

    Модернізація структури соціологічного знання та місце і роль соціологічної рефлексії транспорту в цьому контексті

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    Головний зміст статті полягає в розкритті визначення напрямів модернізації структури соціологічного знання в Україні та шляхи їхнього подолання через обговорення суперечностей в цій справі. Спроба пояснити, чому в соціології має відбутися вибір щодо шляхів модернізації структури спеціальних та галузевих соціологій. Намагання пояснити доцільність опредметнення соціології транспорту як галузі структури соціологічної системи знань. Вказано на головні перспективи подальшого розвитку цієї галузі соціології. Встановлено, що соціологія транспорту в своєму становленні та розвитку має йти в інституціональному напрямку, інтегруючи основні результати, що отримані світовою соціологією, в її рефлексії стосовно: економіки, освіти, управління, організацій, праці, міграції, катастроф, туризму, професійних груп

    Tunneling of correlated electrons in ultra high magnetic field

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    Effects of the electron-electron interaction on tunneling into a metal in ultra-high magnetic field (ultra-quantum limit) are studied. The range of the interaction is found to have a decisive effect both on the nature of the field-induced instability of the ground state and on the properties of the system at energies above the corresponding gap. For a short-range repulsive interaction, tunneling is dominated by the renormalization of the coupling constant, which leads eventually to the charge-density wave instability. For a long-range interaction, there exists an intermediate energy range in which the conductance obeys a power-law scaling form, similar to that of a 1D Luttinger liquid. The exponent is magnetic-field dependent, and more surprisingly, may be positive or negative, i. e., interactions may either suppress or enhance the tunneling conductance compared to its non-interacting value. At energies near the gap, scaling breaks down and tunneling is again dominated by the instability, which in this case is an (anisotropic) Wigner crystal instability.Comment: 4 pages, 2 .eps figure

    Edge electron states for quasi-one-dimensional organic conductors in the magnetic-field-induced spin-density-wave phases

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    We develop a microscopic picture of the electron states localized at the edges perpendicular to the chains in the Bechgaard salts in the quantum Hall regime. In a magnetic-field-induced spin-density-wave state (FISDW) characterized by an integer N, there exist N branches of chiral gapless edge excitations. Localization length is much longer and velocity much lower for these states than for the edge states parallel to the chains. We calculate the contribution of these states to the specific heat and propose a time-of-flight experiment to probe the propagating edge modes directly.Comment: 4 pages, 2 figures. V.2: Minor changes to the final version published in PR

    Fractional ac Josephson effect in unconventional superconductors

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    For certain orientations of Josephson junctions between two p_x-wave or two d-wave superconductors, the subgap Andreev bound states produce a 4pi-periodic relation between the Josephson current I and the phase difference phi: I ~ sin(phi/2). Consequently, the ac Josephson current has the fractional frequency eV/h, where V is the dc voltage. In the tunneling limit, the Josephson current is proportional to the first power (not square) of the electron tunneling amplitude. Thus, the Josephson current between unconventional superconductors is carried by single electrons, rather than by Cooper pairs. The fractional ac Josephson effect can be observed experimentally by measuring frequency spectrum of microwave radiation from the junction.Comment: 8 pages, 3 figures, RevTEX 4; v2. - minor typos corrected in proof

    Superconductivity of Quasi-One and Quasi-Two Dimensional Tight-Binding Electrons in Magnetic Field

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    The upper critical field Hc2(T)H_{c2}(T) of the tight-binding electrons in the three-dimensional lattice is investigated. The electrons make Cooper pairs between the eigenstates with the same energy in the strong magnetic field. The transition lines in the quasi-one dimensional case are shown to deviate from the previously obtained results where the hopping matrix elements along the magnetic field are neglected. In the absence of the Pauli pair breaking the transition temperature Tc(H)T_c(H) of the quasi-two dimensional electrons is obtained to oscillationally increase as the magnetic field becomes large and reaches to Tc(0)T_c(0) in the strong field as in the quasi-one dimensional case.Comment: 4pages,4figures,to be published in J.Phys.Soc.Jp

    Use of a recombinant human follicle-stimulating hormone:recombinant human luteinizing hormone (r-hFSH:r-hLH) 2:1 combination for controlled ovarian stimulation during assisted reproductive technology treatment: A real-world study of routine practice in the Russian Federation

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    Two observational studies in the Russian Federation described patient demographics/clinical decision for treatment with recombinant human follicle-stimulating hormone:recombinant human luteinizing hormone (r-hFSH:r-hLH) 2:1 combination for ovarian stimulation (OS) during assisted reproductive technology (ART) and outcomes, respectively. The first (prospective) study enrolled 500 patients. After post-hoc regrouping to assign patients to discrete groups, 378 (75.6%) met the local Russian label for an r-hFSH:r-hLH 2:1 combination, 105 (21%) were treated according to other physician preference, and 17 (3.4%) met only the ESHRE Bologna criteria for a poor ovarian response. The clinical pregnancy rate per cycle was 30.4%. A total of 158/175 (90.3%) women achieving clinical pregnancy in the prospective study participated in the second (retrospective) study. The live birth rate per cycle was 25.8%. No new safety concerns were reported. These results support the use of the r-hFSH:r-hLH 2:1 combination in patients with a poor/suboptimal response to OS for ART treatment in the Russian Federation

    The role of bile acids and intestinal microbiota in metabolic transformations after gastric bypass surgery

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    Today, the positive impact of bariatric surgery on the course of type 2 diabetes mellitus has been studied in detail. At the same time, not only the effect of direct weight loss and the incretin theory, but also other mechanisms for normalizing glycemia are being actively discussed. Thus, special attention is paid to the metabolism of bile acids and their influence on various indicators of homeostasis, including carbohydrate metabolism. After bariatric interventions of the bypass type, the passage of bile through the gastrointestinal tract, as well as its interaction with food masses, changes significantly, which served as the basis for studying this phenomenon. The information accumulated to date indicates enormous changes occurring not only in the anatomy, but also in the biology of the gastrointestinal tract after bariatric bypass surgery. The composition of the intestinal microbiota and the composition of bile masses undergo significant changes. Most of the works available today suggest that these changes are the cause of a number of metabolic rearrangements, and directly affect carbohydrate metabolism. This issue is still under study and accumulation of the necessary information, but today it can be stated with confidence that the role of bile passage, bile acid circulation and restructuring of the intestinal microbiota in the regulation of carbohydrate metabolism and energy balance after bariatric bypass surgery is of extreme importance

    Ideal MHD theory of low-frequency Alfven waves in the H-1 Heliac

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    A part analytical, part numerical ideal MHD analysis of low-frequency Alfven wave physics in the H-1 stellarator is given. The three-dimensional, compressible ideal spectrum for H-1 is presented and it is found that despite the low beta (approx. 10^-4) of H-1 plasmas, significant Alfven-acoustic interactions occur at low frequencies. Several quasi-discrete modes are found with the three-dimensional linearised ideal MHD eigenmode solver CAS3D, including beta-induced Alfven eigenmode (BAE)- type modes in beta-induced gaps. The strongly shaped, low-aspect ratio magnetic geometry of H-1 causes CAS3D convergence difficulties requiring the inclusion of many Fourier harmonics for the parallel component of the fluid displacement eigenvector even for shear wave motions. The highest beta-induced gap reproduces large parts of the observed configurational frequency dependencies in the presence of hollow temperature profiles

    Organization of rural tourism as a factor of rural development

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    This article is an attempt to study the agricultural tourism and developing recommendations on their organization in the regions of Russia. In the Belgorod region, the development of rural tourism is of fundamental importance for small businesses, which can be traced in regional development program
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