591 research outputs found

    Influence of Fluctuations of the Point-Defects’ Generation Rate and Inhomogeneity of Irradiated F.C.C. Crystal on the Temperature Dependence of the Dissipative-Structure Period in a Spatial Distribution of Radiation Vacancies

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    A kinetic model for the influence of external noise, such as fluctuations of the point-defects’ production rate and inhomogeneity of irradiated f.c.c. crystal, on the formation of modulated defect-distribution structure is considered. Defect-production rate and density of sinks for point defects are simulated as independent uniform and stationary stochastic fields with certain parameters. The interaction between vacancies is taken into account. Such stochastic fields can induce a spatial point-defects’ distribution, which is a stationary uniform stochastic field. Its mean value and correlation functions are estimated, and restricting conditions are determined when this stochastic field becomes unstable because of interaction between defect- density fluctuations and a stochastic field with a spatially-periodic mean value is formed. A formula for evaluating its spatial period is analysed. This geometrical parameter of such a dissipative structure is determined also by kinetic characteristics. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/3543

    Polarons with a twist

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    We consider a polaron model where molecular \emph{rotations} are important. Here, the usual hopping between neighboring sites is affected directly by the electron-phonon interaction via a {\em twist-dependent} hopping amplitude. This model may be of relevance for electronic transport in complex molecules and polymers with torsional degrees of freedom, such as DNA, as well as in molecular electronics experiments where molecular twist motion is significant. We use a tight-binding representation and find that very different polaronic properties are already exhibited by a two-site model -- these are due to the nonlinearity of the restoring force of the twist excitations, and of the electron-phonon interaction in the model. In the adiabatic regime, where electrons move in a {\em low}-frequency field of twisting-phonons, the effective splitting of the energy levels increases with coupling strength. The bandwidth in a long chain shows a power-law suppression with coupling, unlike the typical exponential dependence due to linear phonons.Comment: revtex4 source and one eps figur

    Brane Decay of a (4+n)-Dimensional Rotating Black Hole. II: spin-1 particles

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    The present works complements and expands a previous one, focused on the emission of scalar fields by a (4+n)-dimensional rotating black hole on the brane, by studying the emission of gauge fields on the brane from a similar black hole. A comprehensive analysis of the particle, energy and angular momentum emission rates is undertaken, for arbitrary angular momentum of the black hole and dimensionality of spacetime. Our analysis reveals the existence of a number of distinct features associated with the emission of spin-1 fields from a rotating black hole on the brane, such as the behaviour and magnitude of the different emission rates, the angular distribution of particles and energy, the relative enhancement compared to the scalar fields, and the magnitude of the superradiance effect. Apart from their theoretical interest, these features can comprise clear signatures of the emission of Hawking radiation from a brane-world black hole during its spin-down phase upon successful detection of this effect during an experiment.Comment: 35 pages, 19 figures, Latex fil

    Apolipoprotein J is a hepatokine regulating muscle glucose metabolism and insulin sensitivity

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    Crosstalk between liver and skeletal muscle is vital for glucose homeostasis. Hepatokines, liver-derived proteins that play an important role in regulating muscle metabolism, are important to this communication. Here we identify apolipoprotein J (ApoJ) as a novel hepatokine targeting muscle glucose metabolism and insulin sensitivity through a low-density lipoprotein receptor-related protein-2 (LRP2)-dependent mechanism, coupled with the insulin receptor (IR) signaling cascade. In muscle, LRP2 is necessary for insulin-dependent IR internalization, an initial trigger for insulin signaling, that is crucial in regulating downstream signaling and glucose uptake. Of physiologic significance, deletion of hepatic ApoJ or muscle LRP2 causes insulin resistance and glucose intolerance. In patients with polycystic ovary syndrome and insulin resistance, pioglitazone-induced improvement of insulin action is associated with an increase in muscle ApoJ and LRP2 expression. Thus, the ApoJ-LRP2 axis is a novel endocrine circuit that is central to the maintenance of normal glucose homeostasis and insulin sensitivity

    Dimensional Crossover of Localisation and Delocalisation in a Quantum Hall Bar

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    The 2-- to 1--dimensional crossover of the localisation length of electrons confined to a disordered quantum wire of finite width LyL_y is studied in a model of electrons moving in the potential of uncorrelated impurities. An analytical formula for the localisation length is derived, describing the dimensional crossover as function of width LyL_y, conductance gg and perpendicular magnetic field BB . On the basis of these results, the scaling analysis of the quantum Hall effect in high Landau levels, and the delocalisation transition in a quantum Hall wire are reconsidered.Comment: 12 pages, 7 figure

    Search for Resonant B±K±hK±γγB^{\pm}\to K^{\pm} h \to K^{\pm} \gamma \gamma Decays at Belle

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    We report measurements and searches for resonant B±K±hK±γγB^{\pm} \to K^{\pm} h \to K^{\pm} \gamma \gamma decays where hh is a η,η,ηc,ηc(2S),χc0,χc2,J/ψ\eta,\eta^{\prime},\eta_{c},\eta_{c}(2S),\chi_{c0},\chi_{c2},J/\psi meson or the X(3872) particle.Comment: accepted by Physics Letters

    Competing orders in a magnetic field: spin and charge order in the cuprate superconductors

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    We describe two-dimensional quantum spin fluctuations in a superconducting Abrikosov flux lattice induced by a magnetic field applied to a doped Mott insulator. Complete numerical solutions of a self-consistent large N theory provide detailed information on the phase diagram and on the spatial structure of the dynamic spin spectrum. Our results apply to phases with and without long-range spin density wave order and to the magnetic quantum critical point separating these phases. We discuss the relationship of our results to a number of recent neutron scattering measurements on the cuprate superconductors in the presence of an applied field. We compute the pinning of static charge order by the vortex cores in the `spin gap' phase where the spin order remains dynamically fluctuating, and argue that these results apply to recent scanning tunnelling microscopy (STM) measurements. We show that with a single typical set of values for the coupling constants, our model describes the field dependence of the elastic neutron scattering intensities, the absence of satellite Bragg peaks associated with the vortex lattice in existing neutron scattering observations, and the spatial extent of charge order in STM observations. We mention implications of our theory for NMR experiments. We also present a theoretical discussion of more exotic states that can be built out of the spin and charge order parameters, including spin nematics and phases with `exciton fractionalization'.Comment: 36 pages, 33 figures; for a popular introduction, see http://onsager.physics.yale.edu/superflow.html; (v2) Added reference to new work of Chen and Ting; (v3) reorganized presentation for improved clarity, and added new appendix on microscopic origin; (v4) final published version with minor change

    Search for lepton-flavor-violating τV0\tau\to\ell V^0 decays at Belle

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    We have searched for neutrinoless τ\tau lepton decays into \ell and V0V^0, where \ell stands for an electron or muon, and V0V^0 for a vector meson (ϕ\phi, ω\omega, K0K^{*0}, Kˉ0\bar{K}^{*0} or ρ0\rho^0), using 543 fb1^{-1} of data collected with the Belle detector at the KEKB asymmetric-energy e+ee^+e^- collider. No excess of signal events over the expected background has been observed, and we set upper limits on the branching fractions in the range (5.918)×108(5.9-18) \times 10^{-8} at the 90% confidence level. These upper limits include the first results for the ω\ell \omega mode as well as new limits that are significantly more restrictive than our previous results for the ϕ\ell \phi, K0\ell K^{*0}, Kˉ0\ell \bar{K}^{*0} and ρ0\ell \rho^0 modes.Comment: 7 pages, 16 figure
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