358 research outputs found

    Quasiquarks in two stream system

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    We study the collective quark excitations in an extremely anisotropic system of two interpenetrating streams of the quark-gluon plasma. In contrast to the gluon modes, all quark ones appear to be stable in such a system. Even more, the quark modes in the two-stream system are very similar to those in the isotropic plasma.Comment: 4 pages, 2 figures, minor corrections, to appear in Phys. Rev.

    Rotating vortex dipoles in ferromagnets

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    Vortex-antivortex pairs are localized excitations and have been found to be spontaneously created in magnetic elements. In the case that the vortex and the antivortex have opposite polarities the pair has a nonzero topological charge, and it behaves as a rotating vortex dipole. We find theoretically, and confirm numerically, the form of the energy as a function of the angular momentum of the system and the associated rotation frequencies. We discuss the process of annihilation of the pair which changes the topological charge of the system by unity while its energy is monotonically decreasing. Such a change in the topological charge affects profoundly the dynamics in the magnetic system. We finally discuss the connection of our results with Bloch Points (BP) and the implications for BP dynamics.Comment: 6 pages, 2 figure

    Continuous and inverse shadowing

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    By the Shadowing Lemma we can shadow any sufficient accurate pseudo-trajectory of a hyperbolic system by a true trajectory of a hyperbolic system. If we are interested in finite trajectories, at least from one side, then a pseudo trajectory usually has many possible shadows. Here we show that we can choose a continuous single-valued selector from the corresponding multi-valued operator "pseudo-trajectory ↦ the totality of possible shadows". We do this in the context of Lipschitz mappings which are semi-hyperbolic on some compact subset, which need not be invariant. We also prove that semi-hyperbolicity implis inverse shadowing with respect to a very broad class of nonsmooth perturbations

    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

    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

    Thermal non-equilibrium effects in quantum reflection

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    We show that the quantum reflection coefficient of ultracold heavy atoms scattering off a dielectric surface can be tuned in a wide range by suitable choice of surface and environment temperatures. This effect results from a temperature dependent long-range repulsive part of the van der Waals-Casimir-Polder-Lifshitz atom-surface interaction potential

    Correction of Experimental Retinal Ischemia by L-Isomer of Ethylmethylhydroxypyridine Malate

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    An important task of pharmacology and ophtalmology is to find specific and highly effective agents for correcting retinal ischemia. The objective of this study is to increase the effectiveness of pharmacological correction of retinal ischemia by using new 3-hydroxypyridine derivative-L-isomer of ethylmethylhydroxypyridine malat

    Disorder-driven superconductor-normal metal phase transition in quasi-one-dimensional organic conductors

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    Effects of non-magnetic disorder on the critical temperature T_c and on diamagnetism of quasi-one-dimensional superconductors are reported. The energy of Josephson-coupling between wires is considered to be random, which is typical for dirty organic superconductors. We show that this randomness destroys phase coherence between wires and that T_c vanishes discontinuously at a critical disorder-strength. The parallel and transverse components of the penetration-depth are evaluated. They diverge at different critical temperatures T_c^{(1)} and T_c, which correspond to pair-breaking and phase-coherence breaking respectively. The interplay between disorder and quantum phase fluctuations is shown to result in quantum critical behavior at T=0, which manifests itself as a superconducting-normal metal phase transition of first-order at a critical disorder strength.Comment: 12 pages, 3 figure

    Test-system for estimation of activity of GSK-3 inhibitors as antihypoxants and differentiation of endothelial progenitors in vitro

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    A model test-system was developed for validation in vitro of antihypoxic and endothelio-differentiating activity of newly created glycogen synthase kinase-3 inhibitors in comparison with the reference drug β4-thymosi

    Use of L-arginine immobilised on activated carbon for pharmacological correction of endothelial disfunction

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    For the first time a complex of L-arginine sodium salt of sulfate of cellulose acetate on activated carbon. To investigate the processes of sorption-desorption of L-arginine in a model environmen
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