3,585 research outputs found
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
Role of aggressivity on reactivity and craving before and after cue exposure in recently detoxified alcoholics: Results from an experimental study
The role of aggressivity and cue exposure in induction of craving were investigated in a clinical setting. Thirty abstinent alcoholic patients were divided into a low and a high aggressive group based on scores on the physical aggression subscale of the Buss-Durkee Hostility Inventory and exposed to alcohol cues. Craving was measured by means of the Alcohol Craving Questionnaire (ACQ) and Visual Analogue Scales (VAS). Important findings are: (1) main effects of aggressivity on `emotionality', `purposefulness' and `expectancy' of ACQ were very significant; (2) on `drinking intention' and `craving for alcohol' of VAS, aggressivity and cue exposure showed a significant interaction; (3) the main effect of cue exposure on heart rate also reached a significance level of 0.007. The results were discussed in the context of the Classical, Operant Conditioning Theory, the Cognitive Craving Theory of Tiffany, Gilbert's STAR Model, and the Self-Medication Hypothesis Copyright (C) 2001 S. Karger AG, Basel
Effects of irritability on craving before and after cue exposure in abstinent alcoholic inpatients: Experimental data on subjective response and heart rate
Objective: Irritability is often linked with problem drinking. The aim of this study is to examine the possible influence of irritability on craving induced by a cue-exposure paradigm. Methods: 30 male abstinent alcoholic inpatients of the Psychiatric Hospital of Munich University, Germany gave answers to a series of personality questionnaires. Results of this study concerning the impact of aggressivity on craving for alcohol has recently been published. In this study, the subjects were subdivided into a low- and a high-irritable group based on their scores on the irritability subscale of the Buss-Durkee Hostility Inventory and were exposed to alcohol cues. Craving was measured by means of the Alcohol Craving Questionnaire (ACQ) and Visual Analogue Scales (VAS). The heart rate was also assessed throughout the whole process. ANCOVA for repeated measurement was employed to evaluate the data - irritability disposition as the between-subject factor and the experimental manipulation (absence vs. presence of alcohol cues) as the within-subject factor. Results: Major findings are: (1) main effects of irritability on `emotionality', `purposefulness', and `expectancy' of the ACQ as well as on `craving for alcohol' of the VAS were significant; (2) cue exposure also exerted a significant main effect on I craving for alcohol' of the VAS and on the heart rate after the presentation of alcohol cues; (3) on `compulsivity' of the ACQ and `intention to alcohol intake' of the VAS; there was a significant interaction between irritability and cue exposure. The high-irritable alcoholics, compared with their statements in the baseline, tended to report a higher control over alcohol intake and a lower intention to alcohol use after cue exposure. However, after confrontation with alcohol stimuli, their low-irritable counterparts reported a much lower control and a slightly higher intention than they did in the baseline. Conclusions: The results of this study indicate that induced craving in hospitalized alcohol addicts probably varies with the magnitude of their irritability; it might make patients more aware of their vulnerability to alcohol, help them develop more differential coping strategies and improve medical therapy against alcohol craving. Copyright (C) 2002 S. Karger AG, Basel
On U_q(SU(2))-symmetric Driven Diffusion
We study analytically a model where particles with a hard-core repulsion
diffuse on a finite one-dimensional lattice with space-dependent, asymmetric
hopping rates. The system dynamics are given by the
\mbox{U[SU(2)]}-symmetric Hamiltonian of a generalized anisotropic
Heisenberg antiferromagnet. Exploiting this symmetry we derive exact
expressions for various correlation functions. We discuss the density profile
and the two-point function and compute the correlation length as well
as the correlation time . The dynamics of the density and the
correlations are shown to be governed by the energy gaps of a one-particle
system. For large systems and depend only on the asymmetry. For
small asymmetry one finds indicating a dynamical exponent
as for symmetric diffusion.Comment: 10 pages, LATE
Phase transitions in systems with two species of molecular motors
Systems with two species of active molecular motors moving on (cytoskeletal)
filaments into opposite directions are studied theoretically using driven
lattice gas models. The motors can unbind from and rebind to the filaments. Two
motors are more likely to bind on adjacent filament sites if they belong to the
same species. These systems exhibit (i) Continuous phase transitions towards
states with spontaneously broken symmetry, where one motor species is largely
excluded from the filament, (ii) Hysteresis of the total current upon varying
the relative concentrations of the two motor species, and (iii) Coexistence of
traffic lanes with opposite directionality in multi-filament systems. These
theoretical predictions should be experimentally accessible.Comment: 7 pages, 4 figures, epl style (.cls-file included), to appear in
Europhys. Lett. (http://www.edpsciences.org/epl
Competing Glauber and Kawasaki Dynamics
Using a quantum formulation of the master equation we study a kinetic Ising
model with competing stochastic processes: the Glauber dynamics with
probability and the Kawasaki dynamics with probability . Introducing
explicitely the coupling to a heat bath and the mutual static interaction of
the spins the model can be traced back exactly to a Ginzburg Landau functional
when the interaction is of long range order. The dependence of the correlation
length on the temperature and on the probability is calculated. In case
that the spins are subject to flip processes the correlation length disappears
for each finite temperature. In the exchange dominated case the system is
strongly correlated for each temperature.Comment: 9 pages, Revte
Boundary-induced nonequilibrium phase transition into an absorbing state
We demonstrate that absorbing phase transitions in one dimension may be
induced by the dynamics of a single site. As an example we consider a
one-dimensional model of diffusing particles, where a single site at the
boundary evolves according to the dynamics of a contact process. As the rate
for offspring production at this site is varied, the model exhibits a phase
transition from a fluctuating active phase into an absorbing state. The
universal properties of the transition are analyzed by numerical simulations
and approximation techniques.Comment: 4 pages, 4 figures; minor change
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
Hydrodynamics of the zero-range process in the condensation regime
We argue that the coarse-grained dynamics of the zero-range process in the
condensation regime can be described by an extension of the standard
hydrodynamic equation obtained from Eulerian scaling even though the system is
not locally stationary. Our result is supported by Monte Carlo simulations.Comment: 14 pages, 3 figures. v2: Minor alteration
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