123,848 research outputs found
A New S-S' Pair Creation Rate Expression Improving Upon Zener Curves for I-E Plots
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
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
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
Kappa-deformed Statistics and the Formation of a Quark-Gluon Plasma
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
() 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 -deformed statistical mechanics constructed by Kaniadakis
to represent the constituents of the QGP and compare the results with ref. [1].Comment: 2 Figure
Degree spectra for transcendence in fields
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 degree. In other
cases, these spectra may be characterized by the ability to enumerate an
arbitrary set. This is the first proof that a computable field can
fail to have a computable copy with a computable transcendence basis
Galactic oscillations
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
Oscillator strength trends in group IVb homologous ions
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
The location of innovative activity in Europe
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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