5,792 research outputs found
Spectral signature of nonequilibrium conditions
The study of stochastic systems has received considerable interest over the
years. Their dynamics can describe many equilibrium and nonequilibrium
fluctuating systems. At the same time, nonequilibrium constraints interact with
the time evolution in various ways. Here we review the dynamics of stochastic
systems from the viewpoint of nonequilibrium thermodynamics. We explore the
effect of external thermodynamic forces on the possible dynamical regimes and
show that the time evolution can become intrinsically different under
nonequilibrium conditions. For example, nonequilibrium systems with real
dynamical components are similar to equilibrium ones when their state space
dimension N < 5, but this equivalence is lost in higher dimensions. Out of
equilibrium systems thus present new dynamical behaviors with respect to their
equilibrium counterpart. We also study the dynamical modes of generalized,
non-stochastic evolution operators such as those arising in counting
statistics
Bounding the coarse graining error in hidden Markov dynamics
Lumping a Markov process introduces a coarser level of description that is
useful in many contexts and applications. The dynamics on the coarse grained
states is often approximated by its Markovian component. In this letter we
derive finite-time bounds on the error in this approximation. These results
hold for non-reversible dynamics and for probabilistic mappings between
microscopic and coarse grained states
Nonlinear transport effects in mass separation by effusion
Generalizations of Onsager reciprocity relations are established for the
nonlinear response coefficients of ballistic transport in the effusion of
gaseous mixtures. These generalizations, which have been established on the
basis of the fluctuation theorem for the currents, are here considered for mass
separation by effusion. In this kinetic process, the mean values of the
currents depend nonlinearly on the affinities or thermodynamic forces
controlling the nonequilibrium constraints. These nonlinear transport effects
are shown to play an important role in the process of mass separation. In
particular, the entropy efficiency turns out to be significantly larger than it
would be the case if the currents were supposed to depend linearly on the
affinities
Under-approximating Cut Sets for Reachability in Large Scale Automata Networks
In the scope of discrete finite-state models of interacting components, we
present a novel algorithm for identifying sets of local states of components
whose activity is necessary for the reachability of a given local state. If all
the local states from such a set are disabled in the model, the concerned
reachability is impossible. Those sets are referred to as cut sets and are
computed from a particular abstract causality structure, so-called Graph of
Local Causality, inspired from previous work and generalised here to finite
automata networks. The extracted sets of local states form an
under-approximation of the complete minimal cut sets of the dynamics: there may
exist smaller or additional cut sets for the given reachability. Applied to
qualitative models of biological systems, such cut sets provide potential
therapeutic targets that are proven to prevent molecules of interest to become
active, up to the correctness of the model. Our new method makes tractable the
formal analysis of very large scale networks, as illustrated by the computation
of cut sets within a Boolean model of biological pathways interactions
gathering more than 9000 components
- …