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 $q$-numbers $[n]_q$. This is a generalization of the rates of hopping of noninteracting particles equal to the occupation number $n$ of a site of departure. The noninteracting case can be restored in the limit $q\to 1$. The limiting cases of the model for $q=0,\infty$ 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, $q \ne 1$, 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