49,414 research outputs found

    The effect of non-linear quantum electrodynamics on relativistic transparency and laser absorption in ultra-relativistic plasmas

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    With the aid of large-scale three-dimensional QED-PIC simulations, we describe a realistic experimental configuration to measure collective effects that couple strong field quantum electrodynamics to plasma kinetics. For two counter propagating lasers interacting with a foil at intensities exceeding 102210^{22} Wcm2^{-2}, a binary result occurs; when quantum effects are included, a foil that classically would effectively transmit the laser pulse becomes opaque. This is a dramatic change in plasma behavior, directly as a consequence of the coupling of radiation reaction and pair production to plasma dynamics

    Influence of the charge carrier tunneling processes on the recombination dynamics in single lateral quantum dot molecules

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    We report on the charge carrier dynamics in single lateral quantum dot molecules and the effect of an applied electric field on the molecular states. Controllable electron tunneling manifests itself in a deviation from the typical excitonic decay behavior which is strongly influenced by the tuning electric field and inter-molecular Coulomb energies. A rate equation model is developed to gain more insight into the charge transfer and tunneling mechanisms. Non-resonant (phonon-mediated) electron tunneling which changes the molecular exciton character from direct to indirect, and vice versa, is found to be the dominant tunable decay mechanism of excitons besides radiative recombination.Comment: 4 pages, 4 figure

    Sporopollenin, a natural copolymer, is robust under high hydrostatic pressure

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    Lycopodium sporopollenin, a natural copolymer, shows exceptional stability under high hydrostatic pressures (10 GPa) as determined by in situ high pressure synchrotron source FTIR spectroscopy. This stability is evaluated in terms of the component compounds of the sporopollenin: p-coumaric acid, phloretic acid, ferulic acid, and palmitic and sebacic acids, which represent the additional n-acid and ndiacid components. This high stability is attributed to interactions between these components, rather than the exceptional stability of any one molecular component. We propose a biomimetic solution for the creation of polymer materials that can withstand high pressures for a multitude of uses in aeronautics, vascular autografts, ballistics and light-weight protective materials

    Magnitude and Sign Correlations in Heartbeat Fluctuations

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    We propose an approach for analyzing signals with long-range correlations by decomposing the signal increment series into magnitude and sign series and analyzing their scaling properties. We show that signals with identical long-range correlations can exhibit different time organization for the magnitude and sign. We find that the magnitude series relates to the nonlinear properties of the original time series, while the sign series relates to the linear properties. We apply our approach to the heartbeat interval series and find that the magnitude series is long-range correlated, while the sign series is anticorrelated and that both magnitude and sign series may have clinical applications.Comment: 4 pages,late

    Mesons and Nucleons in Soft-Wall AdS/QCD with Constrained Infrared Background

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    The purpose of this paper is to further study the soft-wall AdS/QCD model with constrained IR background. By including a quartic bulk scalar potential we study various meson and nucleon spectra. This model naturally realizes the asymptotical linearity of these mass spectra simultaneously, together with correctly pattern of explicit and dynamical chiral symmetry breaking. The agreement between the theoretical calculations and the experimental data is good.Comment: 17 pages,5 table

    Lower bounds on the blow-up rate of the axisymmetric Navier-Stokes equations II

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    Consider axisymmetric strong solutions of the incompressible Navier-Stokes equations in R3\R^3 with non-trivial swirl. Let zz denote the axis of symmetry and rr measure the distance to the z-axis. Suppose the solution satisfies either v(x,t)Ct1/2|v (x,t)| \le C_*{|t|^{-1/2}} or, for some \e > 0, v(x,t)Cr1+ϵtϵ/2|v (x,t)| \le C_* r^{-1+\epsilon} |t|^{-\epsilon /2} for T0t<0-T_0\le t < 0 and 0<C<0<C_*<\infty allowed to be large. We prove that vv is regular at time zero.Comment: More explanations and a new appendi
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