2,761 research outputs found
Magnetophoresis of Tagged Polymers
We present quantitative results for the drift velocity of a polymer in a gel
if a force (e.g. through an electric or magnetic field) acts on a tag, attached
to one of its ends. This is done by introducing a modification of the
Rubinstein-Duke model for electrophoresis of DNA. We analyze this modified
model with exact and Monte Carlo calculations. Tagged magnetophoresis does not
show band collapse, a phenomenon that limits the applicability of traditional
electrophoresis to short polymers.Comment: 10 pages revtex, 3 PostScript figure
Phase Coexistence in Driven One Dimensional Transport
We study a one-dimensional totally asymmetric exclusion process with random
particle attachments and detachments in the bulk. The resulting dynamics leads
to unexpected stationary regimes for large but finite systems. Such regimes are
characterized by a phase coexistence of low and high density regions separated
by domain walls. We use a mean-field approach to interpret the numerical
results obtained by Monte-Carlo simulations and we predict the phase diagram of
this non-conserved dynamics in the thermodynamic limit.Comment: 4 pages, 3 figures. Accepted for publication on Phys. Rev. Let
Infinite reflections of shock fronts in driven diffusive systems with two species
Interaction of a domain wall with boundaries of a system is studied for a
class of stochastic driven particle models. Reflection maps are introduced for
the description of this process. We show that, generically, a domain wall
reflects infinitely many times from the boundaries before a stationary state
can be reached. This is in an evident contrast with one-species models where
the stationary density is attained after just one reflection.Comment: 11 pages, 8 eps figs, to appearin JPhysA 01.200
Bethe ansatz solution of zero-range process with nonuniform stationary state
The eigenfunctions and eigenvalues of the master-equation for zero range
process with totally asymmetric dynamics on a ring are found exactly using the
Bethe ansatz weighted with the stationary weights of particle configurations.
The Bethe ansatz applicability requires the rates of hopping of particles out
of a site to be the -numbers . This is a generalization of the rates
of hopping of noninteracting particles equal to the occupation number of a
site of departure. The noninteracting case can be restored in the limit . The limiting cases of the model for correspond to the totally
asymmetric exclusion process, and the drop-push model respectively. We analyze
the partition function of the model and apply the Bethe ansatz to evaluate the
generating function of the total distance travelled by particles at large time
in the scaling limit. In case of non-zero interaction, , the
generating function has the universal scaling form specific for the
Kardar-Parizi-Zhang universality class.Comment: 7 pages, Revtex4, mistypes correcte
Non-equilibrium Dynamics of Finite Interfaces
We present an exact solution to an interface model representing the dynamics
of a domain wall in a two-phase Ising system. The model is microscopically
motivated, yet we find that in the scaling regime our results are consistent
with those obtained previously from a phenomenological, coarse-grained Langevin
approach.Comment: 12 pages LATEX (figures available on request), Oxford preprint
OUTP-94-07
Queueing process with excluded-volume effect
We introduce an extension of the M/M/1 queueing process with a spatial
structure and excluded- volume effect. The rule of particle hopping is the same
as for the totally asymmetric simple exclusion process (TASEP). A
stationary-state solution is constructed in a slightly arranged matrix product
form of the open TASEP. We obtain the critical line that separates the
parameter space depending on whether the model has the stationary state. We
calculate the average length of the model and the number of particles and show
the monotonicity of the probability of the length in the stationary state. We
also consider a generalization of the model with backward hopping of particles
allowed and an alternate joined system of the M/M/1 queueing process and the
open TASEP.Comment: 9 figure
Shocks in the asymmetric exclusion process with internal degree of freedom
We determine all families of Markovian three-states lattice gases with pair
interaction and a single local conservation law. One such family of models is
an asymmetric exclusion process where particles exist in two different
nonconserved states. We derive conditions on the transition rates between the
two states such that the shock has a particularly simple structure with minimal
intrinsic shock width and random walk dynamics. We calculate the drift velocity
and diffusion coefficient of the shock.Comment: 26 pages, 1 figur
On the solvable multi-species reaction-diffusion processes
A family of one-dimensional multi-species reaction-diffusion processes on a
lattice is introduced. It is shown that these processes are exactly solvable,
provided a nonspectral matrix equation is satisfied. Some general remarks on
the solutions to this equation, and some special solutions are given. The
large-time behavior of the conditional probabilities of such systems are also
investigated.Comment: 13 pages, LaTeX2
Why spontaneous symmetry breaking disappears in a bridge system with PDE-friendly boundaries
We consider a driven diffusive system with two types of particles, A and B,
coupled at the ends to reservoirs with fixed particle densities. To define
stochastic dynamics that correspond to boundary reservoirs we introduce
projection measures. The stationary state is shown to be approached dynamically
through an infinite reflection of shocks from the boundaries. We argue that
spontaneous symmetry breaking observed in similar systems is due to placing
effective impurities at the boundaries and therefore does not occur in our
system. Monte-Carlo simulations confirm our results.Comment: 24 pages, 7 figure
The nature of the recent extreme outburst of the Herbig Be/FU Ori binary Z CMa
Z CMa is a binary system which consists of two young stars: A Herbig AeBe
component "Z CMa NW" embedded in a dust cocoon and a less massive component "Z
CMa SE", which is classified as a FU Orionis type star. Recently, the system
showed the largest outburst reported during the almost 90 years of available
observations. During the recent outburst we detect that the Z CMa system is
polarized by 2.6% in the continuum and emission line spectrum, with a position
angle still perpendicular to the jet. From the high level of polarization we
conclude that the outburst is associated with the dust embedded Herbig AeBe NW
component. The main result of our studies is that the bolometric luminosity of
Z CMa remained surprisingly constant during the recent "outburst". We conclude
that either the geometry of the cavity through which the light escapes from the
cocoon has opened a new path, or that the screen of dust, which reflects the
light toward the observer became more efficient causing the observed increase
of the visual brightness by about 2.5 magnitudes.Comment: letter to A&A, accepted 17/12/200
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