Biomedical subjects

J Łuczka

Publications and source records attributed to J Łuczka.

4 recordsLinked to original sources

PubMed2006

Dynamical bimodality in equilibrium monostable systems.

General features of the stochastic dynamics of classical systems approaching a thermodynamic equilibrium Gibbs state are studied via the numerical analysis of time-dependent solutions of the Fokker-Planck equation for an overdamped particle in various monostable potentials. A large class of initial states can dynamically bifurcate during its time evolution into bimodal transient states, which in turn wear off when approaching the long-time regime. Suitable quantifiers characterizing this transient dynamical bimodality, such as its lifetime, the positions of maxima, and the time-dependent well depth of the probability distribution, are analyzed. Some potential applications are pointed out that make use of this interesting principle which is based on an appropriately chosen initial preparation procedure.

Journal Article↗

PubMed2005

Non-Markovian stochastic processes: colored noise.

We survey classical non-Markovian processes driven by thermal equilibrium or nonequilibrium (nonthermal) colored noise. Examples of colored noise are presented. For processes driven by thermal equilibrium noise, the fluctuation-dissipation relation holds. In consequence, the system has to be described by a generalized (integro-differential) Langevin equation with a restriction on the damping integral kernel: Its form depends on the correlation function of noise. For processes driven by nonequilibrium noise, there is no such a restriction: They are considered to be described by stochastic differential (Ito- or Langevin-type) equations with an independent noise term. For the latter, we review methods of analysis of one-dimensional systems driven by Ornstein-Uhlenbeck noise.

Artifacts↗

PubMed2004

Brownian motors: current fluctuations and rectification efficiency.

With this work, we investigate an often neglected aspect of Brownian motor transport, namely, the role of fluctuations of the noise-induced current and its consequences for the efficiency of rectifying noise. In doing so, we consider a Brownian inertial motor that is driven by an unbiased monochromatic, time-periodic force and thermal noise. Typically, we find that the asymptotic, time-, and noise-averaged transport velocities are small, possessing rather broad velocity fluctuations. This implies a corresponding poor performance for the rectification power. However, for tailored profiles of the ratchet potential and appropriate drive parameters, we can identify a drastic enhancement of the rectification efficiency. This regime is marked by persistent, unidirectional motion of the Brownian motor with few back-turns only. The corresponding asymmetric velocity distribution is then rather narrow, with a support that predominantly favors only one sign for the velocity.

Computer Simulation↗

PubMed2001

Transport of particles for a spatially periodic stochastic system with correlated noises.

The transport of particles for a spatially periodic stochastic system driven by two multiplicative noises and one additive noise (between which there are correlations) is investigated for the overdamped and underdamped cases. It is shown that (i) the probability current can be positive, zero, or negative; (ii) the movement of the particles represents the phenomenon of resonance as a function of the additive noise strength. For the underdamped case, the particles with different mass can be separated by controlling the system or the noise parameters. In particular, a reversal of the flux can be induced by controlling the correlations between the additive and multiplicative noises.

Journal Article↗