352 research outputs found

    Contributions of spontaneous phase slippage to linear and non-linear conduction near the Peierls transition in thin samples of o-TaS_3

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    In the Peierls state very thin samples of TaS_3 (cross-section area \sim 10^{-3} mkm^2) are found to demonstrate smearing of the I-V curves near the threshold field. With approaching the Peierls transition temperature, T_P, the smearing evolves into smooth growth of conductance from zero voltage interpreted by us as the contribution of fluctuations to the non--linear conductance. We identify independently the fluctuation contribution to the linear conductance near T_P. Both linear and non-linear contributions depend on temperature with close activation energies \sim (2 - 4) x 10^3 K and apparently reveal the same process. We reject creep of the {\it continuous} charge-density waves (CDWs) as the origin of this effect and show that it is spontaneous phase slippage that results in creep of the CDW. A model is proposed accounting for both the linear and non-linear parts of the fluctuation conduction up to T_P.Comment: 6 pages, 5 Postscript figure, RevTeX, accepted for publication in PR

    Human recombinant erythropoietin gradient dosage influence on ischemic and reperfusion liver injury

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    We investigate influence of human recombinant erythropoietin different dosage on blood flow velocity and morphological changes in liver during ischemic and reperfusion injury. It was proved what optimal preconditioning dosage is 50 IU/k

    The 3d-to-4s-by-2p highway to superconductivity in cuprates

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    High-temperature superconductors are nowadays found in great variety and hold technological promise. It is still an unsolved mystery that the critical temperature T_c of the basic cuprates is so high. The answer might well be hidden in a conventional corner of theoretical physics, overlooked in the recent hunt for exotic explanations of new effects in these materials. A forgotten intra-atomic s-d two-electron exchange in the Cu atom is found to provide a strong (~eV) electron pairing interaction. A Bardeen-Cooper-Schrieffer approach can explain the main experimental observations and predict the correct d_{x^2-y^2} symmetry of the gap.Comment: 4 pages, 3 figures, LaTeX2

    Study of the microcirculation level in bone with osteoporosis and osteoporotic fractures during therapy with recombinant erythropoietin, rosuvastatin and their combinations

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    The experiment was carried out in female white Wistar rats. The effects of recombinant erythropoietin, rosuvastatin and their combination were investigated based on the blood supply to the bone after a modelled experimental osteoporosis. It was found that the studied drugs prevent decrease of bone microcirculation in cases of osteoporosis and in callus tissue in experimental osteoporotic fractures, positively influencing the course of reparative regeneration of bone tissu

    Fermion Analogy for Layered Superconducting Films in Parallel Magnetic Field

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    The equivalence between the Lawrence-Doniach model for films of extreme type-II layered superconductors and a generalization of the back-scattering model for spin-1/2 electrons in one dimension is demonstrated. This fermion analogy is then exploited to obtain an anomalous H1H_{\parallel}^{-1} tail for the parallel equilibrium magnetization of the minimal double layer case in the limit of high parallel magnetic fields HH_{\parallel} for temperatures in the critical regime.Comment: 11 pages of plain TeX, 1 postscript figur

    The Stokes Phenomenon and Schwinger Vacuum Pair Production in Time-Dependent Laser Pulses

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    Particle production due to external fields (electric, chromo-electric or gravitational) requires evolving an initial state through an interaction with a time-dependent background, with the rate being computed from a Bogoliubov transformation between the in and out vacua. When the background fields have temporal profiles with sub-structure, a semiclassical analysis of this problem confronts the full subtlety of the Stokes phenomenon: WKB solutions are only local, while the production rate requires global information. Incorporating the Stokes phenomenon, we give a simple quantitative explanation of the recently computed [Phys. Rev. Lett. 102, 150404 (2009)] oscillatory momentum spectrum of e+e- pairs produced from vacuum subjected to a time-dependent electric field with sub-cycle laser pulse structure. This approach also explains naturally why for spinor and scalar QED these oscillations are out of phase.Comment: 5 pages, 4 figs.; v2 sign typo corrected, version to appear in PR

    Study of dose-dependent effect of 2-ethyl-6-methyl-3 hydroxypyridine succinate on the contractile function of isolated rat heat

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    In experiments on the isolated rat heart there were studied the effects of different doses (21.43 mg/kg/day and 85 . 72 mg/kg/day) 2-ethyl-6-methyl-3 hydroxypy ridine succinate ("EkoPharmInvest", Russia), on the contractile function of isolated hearts subjected to prior doxorubicin model (20 mg/kg, intraperitoneal) of pathology. The dynamic of the power mechanisms of ion transport was evaluated by imposing high h eart rate (480 BPM) and increase concentration of Са2+ to 5 mmol in perfusat

    Endothelio- and cardioprotective effects of vitamin B₆ and folic acid in modelling methionine-induced hyperhomocysteinemia

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    The endotelio- and cardioprotective effects of vitamin B₆ (2 mg/kg) and folic acid (0.2mg/kg) upon modeling of methionine-induced hyperhomocysteinemia via methionine intragastric administration at a dose of 3 g/kg were studie

    Pharmacological correction of retinal ischemia/reperfusion by minoxidil

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    The objective of this paper was to increase the effectiveness of pharmacological correction of retinal ischemia-reperfusion by using minoxidil. Minoxidil at a dose of 0.5 mg/kg of rat mass protects the retina from ischemic-reperfusion injury. Protective effects of minoxidil are carried out by a preconditioning action, as evidenced by the lack of positive effects with the administration of glibenclamid
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