6,275 research outputs found
Noise in Genotype Selection Model
We study the steady state properties of a genotype selection model in
presence of correlated Gaussian white noise. The effect of the noise on the
genotype selection model is discussed. It is found that correlated noise can
break the balance of gene selection and induce the phase transition which can
makes us select one type gene haploid from a gene group.Comment: 8 pages, 4 figure
Spin-flip reflection at the normal metal-spin superconductor interface
We study spin transport through a normal metal-spin superconductor junction.
A spin-flip reflection is demonstrated at the interface, where a spin-up
electron incident from the normal metal can be reflected as a spin-down
electron and the spin will be injected into the spin
superconductor. When the (spin) voltage is smaller than the gap of the spin
superconductor, the spin-flip reflection determines the transport properties of
the junction. We consider both graphene-based (linear-dispersion-relation) and
quadratic-dispersion-relation normal metal-spin superconductor junctions in
detail. For the two-dimensional graphene-based junction, the spin-flip
reflected electron can be along the specular direction (retro-direction) when
the incident and reflected electron locates in the same band (different bands).
A perfect spin-flip reflection can occur when the incident electron is normal
to the interface, and the reflection coefficient is slightly suppressed for the
oblique incident case. As a comparison, for the one-dimensional
quadratic-dispersion-relation junction, the spin-flip reflection coefficient
can reach 1 at certain incident energies. In addition, both the charge current
and the spin current under a charge (spin) voltage are studied. The spin
conductance is proportional to the spin-flip reflection coefficient when the
spin voltage is less than the gap of the spin superconductor. These results
will help us get a better understanding of spin transport through the normal
metal-spin superconductor junction.Comment: 11 pages, 9 figure
Current Reversals in a inhomogeneous system with asymmetric unbiased fluctuations
We present a study of transport of a Brownian particle moving in periodic
symmetric potential in the presence of asymmetric unbiased fluctuations. The
particle is considered to move in a medium with periodic space dependent
friction. By tuning the parameters of the system, the direction of current
exhibit reversals, both as a function of temperature as well as the amplitude
of rocking force. We found that the mutual interplay between the opposite
driving factors is the necessary term for current reversals.Comment: 9 pages, 7 figure
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