121,866 research outputs found

    A New S-S' Pair Creation Rate Expression Improving Upon Zener Curves for I-E Plots

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    To simplify phenomenology modeling used for charge density wave (CDW)transport, we apply a wavefunctional formulation of tunneling Hamiltonians to a physical transport problem characterized by a perturbed washboard potential. To do so, we consider tunneing between states that are wavefunctionals of a scalar quantum field. I-E curves that match Zener curves - used to fit data experimentally with wavefunctionals congruent with the false vacuum hypothesis. This has a very strong convergence with electron-positron pair production representations.The similarities in plot behavior of the current values after the threshold electric field values argue in favor of the Bardeen pinning gap paradigm proposed for quasi-one-dimensional metallic transport problems.Comment: 22 pages,6 figures, and extensive editing of certain segments.Paper has been revised due to acceptance by World press scientific MPLB journal. This is word version of file which has been submitted to MPLBs editor for final proofing. Due for publication perhaps in mid spring to early summer 200

    Slow modes in Keplerian disks

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    Low-mass disks orbiting a massive body can support "slow" normal modes, in which the eigenfrequency is much less than the orbital frequency. Slow modes are lopsided, i.e., the azimuthal wavenumber m=1. We investigate the properties of slow modes, using softened self-gravity as a simple model for collective effects in the disk. We employ both the WKB approximation and numerical solutions of the linear eigenvalue equation. We find that all slow modes are stable. Discrete slow modes can be divided into two types, which we label g-modes and p-modes. The g-modes involve long leading and long trailing waves, have properties determined by the self-gravity of the disk, and are only present in narrow rings or in disks where the precession rate is dominated by an external potential. In contrast, the properties of p-modes are determined by the interplay of self-gravity and other collective effects. P-modes involve both long and short waves, and in the WKB approximation appear in degenerate leading/trailing pairs. Disks support a finite number---sometimes zero---of discrete slow modes, and a continuum of singular modes.Comment: 32 pages, 12 figures. To be published in Astronomical Journa

    A Poisson process approximation for generalized K-5 confidence regions

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    One-sided confidence regions for continuous cumulative distribution functions are constructed using empirical cumulative distribution functions and the generalized Kolmogorov-Smirnov distance. The band width of such regions becomes narrower in the right or left tail of the distribution. To avoid tedious computation of confidence levels and critical values, an approximation based on the Poisson process is introduced. This aproximation provides a conservative confidence region; moreover, the approximation error decreases monotonically to 0 as sample size increases. Critical values necessary for implementation are given. Applications are made to the areas of risk analysis, investment modeling, reliability assessment, and analysis of fault tolerant systems

    Degree spectra for transcendence in fields

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    We show that for both the unary relation of transcendence and the finitary relation of algebraic independence on a field, the degree spectra of these relations may consist of any single computably enumerable Turing degree, or of those c.e. degrees above an arbitrary fixed Δ20\Delta^0_2 degree. In other cases, these spectra may be characterized by the ability to enumerate an arbitrary Σ20\Sigma^0_2 set. This is the first proof that a computable field can fail to have a computable copy with a computable transcendence basis

    Kappa-deformed Statistics and the Formation of a Quark-Gluon Plasma

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    The effect of the non-extensive form of statistical mechanics proposed by Tsallis on the formation of a quark-gluon plasma (QGP) has been recently investigated in ref. \cite{1}. The results show that for small deviations (≈10\approx 10%) from Boltzmann-Gibbs (BG) statistics in the QGP phase, the critical temperature for the formation of a QGP does not change substantially for a large variation of the chemical potential. In the present effort we use the extensive Îș\kappa-deformed statistical mechanics constructed by Kaniadakis to represent the constituents of the QGP and compare the results with ref. [1].Comment: 2 Figure

    Oscillator strength trends in group IVb homologous ions

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    Shock tube data are used to examine the systematic f value behavior in prominent visible transition arrays (ns-np, np-(n+l)s, np-nd) for the homologous emitter sequence Si 11, Ge 11, Sn 11, and Pb 11. Regularities found for these data are compared with trends in lighter elements. Agreements and s disparities with theoretical and experimental oscillator strengths from the literature are noted

    Galactic oscillations

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    Several oscillations have been identified in spherical galaxy models. These are normal mode oscillations in a stable galaxy. Each has its own distinct period and spatial form, and each rings without detectable damping through a Hubble time. The most important are: (1) a simple radial pulsation (fundamental mode), in which all parts of the galaxy move inward or outward with the same phase; and (2) a second spherically symmetrical radial mode with one node, so material inside the node moves outward when material outside moves inward. Numerical experiments suggest that normal mode oscillations may be present in nearly all galaxies at a considerably higher amplitude than has previously been thought. Amplitudes typically run a few percent of equilibrium values, and periods are around 50-300 Myrs in typical galaxies. These time scales are long enough that gas trapped near the center could cool during an oscillation cycle, allowing star formation activity. The second mode oscillations could cause bursts of star formation

    The location of innovative activity in Europe

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    In this paper we use new data to describe how firms from 15 European countries organise their innovative activities. The data matches firm level accounting data with information on the patents that those firms and their subsidiaries have applied for at the European Patents Office. We describe the data in detail
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