27,194 research outputs found
Entropy production and rectification efficiency in colloids transport along a pulsating channel
We study the current rectification of particles moving in a pulsating channel
under the in uence of an applied force. We have shown the existence of diferent
rectification scenarios in which entropic and energetic effects compete. The
effect can be quantified by means of a rectification coefficient that is
analyzed in terms of the force, the frequency and the diffusion coefficient.
The energetic cost of the motion of the particles expressed in terms of the
entropy production depends on the importance of the entropic contribution to
the total force. Rectification is more important at low values of the applied
force when entropic effects become dominant. In this regime, the entropy
production is not invariant under reversal of the applied force. The phenomenon
observed could be used to optimize transport in microfluidic devices or in
biological channels
Dynamical correlations near dislocation jamming
Dislocation assemblies exhibit a jamming or yielding transition at a critical
external shear stress value . Nevertheless the nature of this
transition has not been ascertained. Here we study the heterogeneous and
collective nature of dislocation dynamics within a crystal plasticity model
close to , by considering the first-passage properties of the
dislocation dynamics. As the transition is approached in the moving phase, the
first passage time distribution exhibits scaling, and a related peak {\it
dynamical} susceptibility diverges as , with . We relate this scaling
to an avalanche description of the dynamics. While the static structural
correlations are found to be independent of the external stress, we identify a
diverging dynamical correlation length in the direction perpendicular
to the dislocation glide motion.Comment: 4 pages, 5 figure
A model for cross-cultural reciprocal interactions through mass media
We investigate the problem of cross-cultural interactions through mass media
in a model where two populations of social agents, each with its own internal
dynamics, get information about each other through reciprocal global
interactions. As the agent dynamics, we employ Axelrod's model for social
influence. The global interaction fields correspond to the statistical mode of
the states of the agents and represent mass media messages on the cultural
trend originating in each population. Several phases are found in the
collective behavior of either population depending on parameter values: two
homogeneous phases, one having the state of the global field acting on that
population, and the other consisting of a state different from that reached by
the applied global field; and a disordered phase. In addition, the system
displays nontrivial effects: (i) the emergence of a largest minority group of
appreciable size sharing a state different from that of the applied global
field; (ii) the appearance of localized ordered states for some values of
parameters when the entire system is observed, consisting of one population in
a homogeneous state and the other in a disordered state. This last situation
can be considered as a social analogue to a chimera state arising in globally
coupled populations of oscillators.Comment: 8 pages and 7 figure
Nonequilibrium transitions induced by multiplicative noise
A new simple model exhibiting a noise-induced ordering transition (NIOT) and
a noise-induced disordering transition (NIDT), in which the noise is purely
multiplicative, is presented. Both transitions are found in two as well as in
one dimension (where they had not been previously reported). We show
analytically and numerically that the critical behavior of these two
transitions is described by the so called multiplicative noise(MN) universality
class. A computation of the set of critical exponents is presented in both
, and (where they have not been previously measured).Comment: 4 pages, 2 figures, Late
Dynamics of link states in complex networks: The case of a majority rule
Motivated by the idea that some characteristics are specific to the relations
between individuals and not of the individuals themselves, we study a prototype
model for the dynamics of the states of the links in a fixed network of
interacting units. Each link in the network can be in one of two equivalent
states. A majority link-dynamics rule is implemented, so that in each dynamical
step the state of a randomly chosen link is updated to the state of the
majority of neighboring links. Nodes can be characterized by a link
heterogeneity index, giving a measure of the likelihood of a node to have a
link in one of the two states. We consider this link-dynamics model on fully
connected networks, square lattices and Erd \"os-Renyi random networks. In each
case we find and characterize a number of nontrivial asymptotic configurations,
as well as some of the mechanisms leading to them and the time evolution of the
link heterogeneity index distribution. For a fully connected network and random
networks there is a broad distribution of possible asymptotic configurations.
Most asymptotic configurations that result from link-dynamics have no
counterpart under traditional node dynamics in the same topologies.Comment: 9 pages, 13 figure
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