4,636 research outputs found
Instabilities and propagation of neutrino magnetohydrodynamic waves in arbitrary direction
In a previous work [16], a new model was introduced, taking into account the
role of the Fermi weak force due to neutrinos coupled to magnetohydrodynamic
plasmas. The resulting neutrino-magnetohydrodynamics was investigated in a
particular geometry associated with the magnetosonic wave, where the ambient
magnetic field and the wavevector are perpendicular. The corresponding fast,
short wavelength neutrino beam instability was then obtained in the context of
supernova parameters. The present communication generalizes these results,
allowing for arbitrary direction of wave propagation, including fast and slow
magnetohydrodynamic waves and the intermediate cases of oblique angles. The
numerical estimates of the neutrino-plasma instabilities are derived in extreme
astrophysical environments where dense neutrino beams exist
Evolution of the Dark Matter Distribution at the Galactic Center
Annihilation radiation from neutralino dark matter at the Galactic center
(GC) would be greatly enhanced if the dark matter were strongly clustered
around the supermassive black hole (SBH). The existence of a dark-matter
"spike" is made plausible by the observed, steeply-rising stellar density near
the GC SBH. Here the time-dependent equations describing gravitational
interaction of the dark matter particles with the stars are solved. Scattering
of dark matter particles by stars would substantially lower the dark matter
density near the GC SBH over 10^10 yr, due both to kinetic heating, and to
capture of dark matter particles by the SBH. This result suggests that
enhancements in the dark matter density around a SBH would be modest whether or
not the host galaxy had experienced the scouring effects of a binary SBH.Comment: 5 pages, 3 figures. Submitted to Physical Review Letter
Issues of alcohol safety in the Vologda oblast
The article presents the destructive social processes and threats to alcohol safety. The estimation of the basic indicators of production and consumption of alcoholic beverages in the region. The study of the international experience of regulate alcohol consumption, the necessity of toughening of state regulation of turnover of alcoholic products
Phase Transition in Two Species Zero-Range Process
We study a zero-range process with two species of interacting particles. We
show that the steady state assumes a simple factorised form, provided the
dynamics satisfy certain conditions, which we derive. The steady state exhibits
a new mechanism of condensation transition wherein one species induces the
condensation of the other. We study this mechanism for a specific choice of
dynamics.Comment: 8 pages, 3 figure
Chromosome mapping: radiation hybrid data and stochastic spin models
This work approaches human chromosome mapping by developing algorithms for
ordering markers associated with radiation hybrid data. Motivated by recent
work of Boehnke et al. [1], we formulate the ordering problem by developing
stochastic spin models to search for minimum-break marker configurations. As a
particular application, the methods developed are applied to 14 human
chromosome-21 markers tested by Cox et al. [2]. The methods generate
configurations consistent with the best found by others. Additionally, we find
that the set of low-lying configurations is described by a Markov-like ordering
probability distribution. The distribution displays cluster correlations
reflecting closely linked loci.Comment: 26 Pages, uuencoded LaTex, Submitted to Phys. Rev. E,
[email protected], [email protected]
Transport of interface states in the Heisenberg chain
We demonstrate the transport of interface states in the one-dimensional
ferromagnetic Heisenberg model by a time dependent magnetic field. Our analysis
is based on the standard Adiabatic Theorem. This is supplemented by a numerical
analysis via the recently developed time dependent DMRG method, where we
calculate the adiabatic constant as a function of the strength of the magnetic
field and the anisotropy of the interaction.Comment: minor revision, final version; 13 pages, 4 figure
Nonlinear theory of resonant slow waves in anisotropic and dispersive plasmas
The solar corona is a typical example of a plasma with strongly anisotropic transport processes. The main dissipative mechanisms in the solar corona acting on slow magnetoacoustic waves are the anisotropic thermal conductivity and viscosity [Ballai et al., Phys. Plasmas 5, 252 (1998)] developed the nonlinear theory of driven slow resonant waves in such a regime. In the present paper the nonlinear behavior of driven magnetohydrodynamic waves in the slow dissipative layer in plasmas with strongly anisotropic viscosity and thermal conductivity is expanded by considering dispersive effects due to Hall currents. The nonlinear governing equation describing the dynamics of nonlinear resonant slow waves is supplemented by a term which describes nonlinear dispersion and is of the same order of magnitude as nonlinearity and dissipation. The connection formulas are found to be similar to their nondispersive counterparts
Locating the minimum : Approach to equilibrium in a disordered, symmetric zero range process
We consider the dynamics of the disordered, one-dimensional, symmetric zero
range process in which a particle from an occupied site hops to its nearest
neighbour with a quenched rate . These rates are chosen randomly from the
probability distribution , where is the lower cutoff.
For , this model is known to exhibit a phase transition in the steady
state from a low density phase with a finite number of particles at each site
to a high density aggregate phase in which the site with the lowest hopping
rate supports an infinite number of particles. In the latter case, it is
interesting to ask how the system locates the site with globally minimum rate.
We use an argument based on local equilibrium, supported by Monte Carlo
simulations, to describe the approach to the steady state. We find that at
large enough time, the mass transport in the regions with a smooth density
profile is described by a diffusion equation with site-dependent rates, while
the isolated points where the mass distribution is singular act as the
boundaries of these regions. Our argument implies that the relaxation time
scales with the system size as with for and
suggests a different behaviour for .Comment: Revtex, 7 pages including 3 figures. Submitted to Pramana -- special
issue on mesoscopic and disordered system
Criterion for phase separation in one-dimensional driven systems
A general criterion for the existence of phase separation in driven
one-dimensional systems is proposed. It is suggested that phase separation is
related to the size dependence of the steady-state currents of domains in the
system. A quantitative criterion for the existence of phase separation is
conjectured using a correspondence made between driven diffusive models and
zero-range processes. Several driven diffusive models are discussed in light of
the conjecture
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