2,966 research outputs found
KPZ modes in -dimensional directed polymers
We define a stochastic lattice model for a fluctuating directed polymer in
dimensions. This model can be alternatively interpreted as a
fluctuating random path in 2 dimensions, or a one-dimensional asymmetric simple
exclusion process with conserved species of particles. The deterministic
large dynamics of the directed polymer are shown to be given by a system of
coupled Kardar-Parisi-Zhang (KPZ) equations and diffusion equations. Using
non-linear fluctuating hydrodynamics and mode coupling theory we argue that
stationary fluctuations in any dimension can only be of KPZ type or
diffusive. The modes are pure in the sense that there are only subleading
couplings to other modes, thus excluding the occurrence of modified
KPZ-fluctuations or L\'evy-type fluctuations which are common for more than one
conservation law. The mode-coupling matrices are shown to satisfy the so-called
trilinear condition.Comment: 22 pages, 2 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
Tissue-specific DNase I-hypersensitive sites in the 5´flanking sequences of the trytophane oxygenase and tyrosine aminotransferase genes
The genes for tryptophan oxygenase (TO) and tyrosine aminotransferase (TAT) are expressed in a tissue- and development-specific manner and are regulated by glucocorticoids (TO and TAT) and glucagon or its intracellular mediator cAMP (TAT) in rat liver. We have analyzed the chromatin structure of these genes in the vicinity of the 5' ends with regard to DNaseI hypersensitivity and have found DNaseI hypersensitive sites upstream of each of the promoters. Mapping of this region reveals three closely spaced cleavage sites near the TO promoter and a doublet of sites near the TAT promoter. In both genes additional cleavage sites are found further upstream. All hypersensitive sites of both genes are absent in kidney nuclei and therefore appear to be specific for the tissue expressing the genes. A correlation of expression and modified chromatin structure was also observed in a hepatoma cell line expressing TAT but not TO: hypersensitive sites are present in TAT but not in TO chromatin. Upon glucocorticoid induction an additional hypersensitive site is detected approximately 2 kb upstream of the TAT promoter in liver and hepatoma cells
Green functions for the TASEP with sublattice parallel update
We consider the totally asymmetric simple exclusion process (TASEP) in
discrete time with the sublattice parallel dynamics describing particles moving
to the right on the one-dimensional infinite chain with equal hoping
probabilities. Using sequentially two mappings, we show that the model is
equivalent to the TASEP with the backward-ordered sequential update in the case
when particles start and finish their motion not simultaneously. The Green
functions are obtained exactly in a determinant form for different initial and
final conditions.Comment: 11 pages, 4 figure
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