497 research outputs found
Wigner Functions versus WKB-Methods in Multivalued Geometrical Optics
We consider the Cauchy-problem for a class of scalar linear dispersive
equations with rapidly oscillating initial data. The problem of high-frequency
asymptotics of such models is reviewed,in particular we highlight the
difficulties in crossing caustics when using (time-dependent) WKB-methods.
Using Wigner measures we present an alternative approach to such asymptotic
problems. We first discuss the connection of the naive WKB solutions to
transport equations of Liouville type (with mono-kinetic solutions) in the
prebreaking regime. Further we show that the Wigner measure approach can be
used to analyze high-frequency limits in the post-breaking regime, in
comparison with the traditional Fourier integral operator method. Finally we
present some illustrating examples.Comment: 38 page
On two-temperature problem for harmonic crystals
We consider the dynamics of a harmonic crystal in dimensions with
components,. The initial date is a random function with finite mean
density of the energy which also satisfies a Rosenblatt- or
Ibragimov-Linnik-type mixing condition. The random function converges to
different space-homogeneous processes as , with the
distributions . We study the distribution of the solution at
time . The main result is the convergence of to a Gaussian
translation-invariant measure as . The proof is based on the long
time asymptotics of the Green function and on Bernstein's `room-corridor'
argument. The application to the case of the Gibbs measures
with two different temperatures is given. Limiting mean energy
current density is with some positive constant
what corresponds to Second Law
Treatment of Obesity in Mentally Retarded Persons: The Rehabilitator\u27s Role
Obesity is a common problem for the mentally retarded and nonretarded populations. Prevalence estimates ranging from 40 to 80 million obese Americans have been reported. The relationship between obesity and cardiovascular disease, diabetes mellitus, and other health related problems is strong. Also, the greater the degree of obesity, the higher the risk of medical problems. In addition to the health problems associated with obesity, the obese mentally retarded person is likely to be the object of increased social prejudice and nonacceptance as a result of being mentally retarded and obese.
Fortunately, this solution does not need to be an intractable one. Van Itallie cited studies reporting a positive influence for weight reduction on health. Another treatment goal has been enhanced self-esteem. Given these promising outcomes for weight reduction, the field of obesity has witnessed an explosion of diet programs and exercise regimes to promote weight loss. These programs have varied in their initial success but nearly all have failed to produce long-term maintenance of weight loss. The application of behavioral procedures to the problem of obesity has produced more promising results. This approach has also been successfully extended to the mentally retarded population.
This article describes the treatment rationale and procedures for a behavioral self-control package that has been developed for the obese retarded population. Implications of this approach for professionals concerned with rehabilitation efforts for mentally retarded persons will be delineated
New measure of electron correlation
We propose to quantify the "correlation" inherent in a many-electron (or
many-fermion) wavefunction by comparing it to the unique uncorrelated state
that has the same single-particle density operator as it does.Comment: Final version to appear in PR
The nonrelativistic limit of the Magueijo-Smolin model of deformed special relativity
We study the nonrelativistic limit of the motion of a classical particle in a
model of deformed special relativity and of the corresponding generalized
Klein-Gordon and Dirac equations, and show that they reproduce nonrelativistic
classical and quantum mechanics, respectively, although the rest mass of a
particle no longer coincides with its inertial mass. This fact clarifies the
meaning of the different definitions of velocity of a particle available in DSR
literature. Moreover, the rest mass of particles and antiparticles differ,
breaking the CPT invariance. This effect is close to observational limits and
future experiments may give indications on its effective existence.Comment: 10 pages, plain TeX. Discussion of generalized Dirac equation and CPT
violation adde
corrections to polarized top decay into a charged Higgs
We calculate the radiative corrections to polarized top quark
decay into a charged Higgs boson and a massive bottom quark in two variants of
the two-Higgs-doublet model. The radiative corrections to the polarization
asymmetry of the decay may become as large as . We provide analytical
formulae for the unpolarized and polarized rates for and for . For our closed-form expressions for the unpolarized and
polarized rates become rather compact.Comment: 24 pages, 5 figures in the text, content modified, comments added,
appendices added, references updated, replaced with published versio
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