255 research outputs found
Inhomogeneous Coupling in Two-Channel Asymmetric Simple Exclusion Processes
Asymmetric exclusion processes for particles moving on parallel channels with
inhomogeneous coupling are investigated theoretically. Particles interact with
hard-core exclusion and move in the same direction on both lattices, while
transitions between the channels is allowed at one specific location in the
bulk of the system. An approximate theoretical approach that describes the
dynamics in the vertical link and horizontal lattice segments exactly but
neglects the correlation between the horizontal and vertical transport is
developed. It allows us to calculate stationary phase diagrams, particle
currents and densities for symmetric and asymmetric transitions between the
channels. It is shown that in the case of the symmetric coupling there are
three stationary phases, similarly to the case of single-channel totally
asymmetric exclusion processes with local inhomogeneity. However, the
asymmetric coupling between the lattices lead to a very complex phase diagram
with ten stationary-state regimes. Extensive Monte Carlo computer simulations
generally support theoretical predictions, although simulated stationary-state
properties slightly deviate from calculated in the mean-field approximation,
suggesting the importance of correlations in the system. Dynamic properties and
phase diagrams are discussed by analyzing constraints on the particle currents
across the channels
Parallel Coupling of Symmetric and Asymmetric Exclusion Processes
A system consisting of two parallel coupled channels where particles in one
of them follow the rules of totally asymmetric exclusion processes (TASEP) and
in another one move as in symmetric simple exclusion processes (SSEP) is
investigated theoretically. Particles interact with each other via hard-core
exclusion potential, and in the asymmetric channel they can only hop in one
direction, while on the symmetric lattice particles jump in both directions
with equal probabilities. Inter-channel transitions are also allowed at every
site of both lattices. Stationary state properties of the system are solved
exactly in the limit of strong couplings between the channels. It is shown that
strong symmetric couplings between totally asymmetric and symmetric channels
lead to an effective partially asymmetric simple exclusion process (PASEP) and
properties of both channels become almost identical. However, strong asymmetric
couplings between symmetric and asymmetric channels yield an effective TASEP
with nonzero particle flux in the asymmetric channel and zero flux on the
symmetric lattice. For intermediate strength of couplings between the lattices
a vertical cluster mean-field method is developed. This approximate approach
treats exactly particle dynamics during the vertical transitions between the
channels and it neglects the correlations along the channels. Our calculations
show that in all cases there are three stationary phases defined by particle
dynamics at entrances, at exits or in the bulk of the system, while phase
boundaries depend on the strength and symmetry of couplings between the
channels. Extensive Monte Carlo computer simulations strongly support our
theoretical predictions.Comment: 16 page
Spontaneous Symmetry Breaking in Two-Channel Asymmetric Exclusion Processes with Narrow Entrances
Multi-particle non-equilibrium dynamics in two-channel asymmetric exclusion
processes with narrow entrances is investigated theoretically. Particles move
on two parallel lattices in opposite directions without changing them, while
the channels are coupled only at the boundaries. A particle cannot enter the
corresponding lane if the exit site of the other lane is occupied. Stationary
phase diagrams, particle currents and densities are calculated in a mean-field
approximation. It is shown that there are four stationary phases in the system,
with two of them exhibiting spontaneous symmetry breaking phenomena. Extensive
Monte Carlo computer simulations confirm qualitatively our predictions,
although the phase boundaries and stationary properties deviate from the
mean-field results. Computer simulations indicate that several dynamic and
phase properties of the system have a strong size dependency, and one of the
stationary phases predicted by the mean-field theory disappears in the
thermodynamic limit.Comment: 13 page
Theoretical Investigation of Totally Asymmetric Exclusion Processes on Lattices with Junctions
Totally asymmetric simple exclusion processes on lattices with junctions,
where particles interact with hard-core exclusion and move on parallel lattice
branches that at the junction combine into a single lattice segment, are
investigated. A simple approximate theory, that treats the correlations around
the junction position in a mean-field fashion, is developed in order to
calculate stationary particle currents, density profiles and a phase diagram.
It is shown that there are three possible stationary phases depending on the
state of each of the lattice branch. At first-order phase boundaries, where the
density correlations are important, a modified phenomenological domain-wall
theory, that accounts for correlations, is introduced. Extensive Monte Carlo
computer simulations are performed to investigate the system, and it is found
that they are in excellent agreement with theoretical predictions.Comment: 16 pages, 7 figure
The new media and the evolution of the human psyche
Background. The emergence of the new media — the Internet and social networks — has had a considerable impact not only on media technologies, genres of journalism, and environment the journalist works in, but also on every user of global communication. Ongoing changes are extending their influence to all the media, making it important for researchers to reconsider the role of journalism in modern society and the perspectives
of its development in the information age.
Objective. In order to get an adequate picture of the ongoing changes, we need to understand how the new media impact their users. We studied the dependence of people’s self-identification (values) on their Internet activity and use of social networks.
Our hypothesis was that use of the new media leads to the formation of a new personality type, among whose most distinct characteristics is a much stronger desire for selfdetermination.
Design. The characteristic features of respondents’ self-identification were studied by their choosing a reference group. Their desire for self-determination was revealed by giving them ethical dilemmas. A questionnaire was devised to study their communicative preferences and attitudes. Various methods of mathematical analysis were applied.
Results. Factor analysis revealed two psychological types of people, different from others in how much they use the new media. Statistical analyses of the group comparison
data showed that the desire for self-determination is considerably higher for active users, and is especially high for those who adhere to spiritual values (by the Maslow pyramid).
A two-way ANOVA confirmed the overall effect of these two factors — spiritual values and the new media — on the desire for self-determination.
Conclusion. The data obtained show that the new media support people’s desire for self-determination. Using the new media and thereby acquiring the identify of a journalist becomes an important factor of personality development and is in line with the
general evolution of the psyche
Dynamic Boundaries in Asymmetric Exclusion Processes
We investigate the dynamics of a one-dimensional asymmetric exclusion process
with Langmuir kinetics and a fluctuating wall. At the left boundary, particles
are injected onto the lattice; from there, the particles hop to the right.
Along the lattice, particles can adsorb or desorb, and the right boundary is
defined by a wall particle. The confining wall particle has intrinsic forward
and backward hopping, a net leftward drift, and cannot desorb. Performing Monte
Carlo simulations and using a moving-frame finite segment approach coupled to
mean field theory, we find the parameter regimes in which the wall acquires a
steady state position. In other regimes, the wall will either drift to the left
and fall off the lattice at the injection site, or drift indefinitely to the
right. Our results are discussed in the context of non-equilibrium phases of
the system, fluctuating boundary layers, and particle densities in the lab
frame versus the frame of the fluctuating wall.Comment: 13 page
Balance network of asymmetric simple exclusion process
We investigate a balance network of the asymmetric simple exclusion process
(ASEP). Subsystems consisting of ASEPs are connected by bidirectional links
with each other, which results in balance between every pair of subsystems. The
network includes some specific important cases discussed in earlier works such
as the ASEP with the Langmuir kinetics, multiple lanes and finite reservoirs.
Probability distributions of particles in the steady state are exactly given in
factorized forms according to their balance properties. Although the system has
nonequilibrium parts, the expressions are well described in a framework of
statistical mechanics based on equilibrium states. Moreover, the overall
argument does not depend on the network structures, and the knowledge obtained
in this work is applicable to a broad range of problems
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