It is generally believed that sustained directed transport in mechanical systems is not achievable under equilibrium conditions. In this article, by analyzing a simple model, we will show that directed motion under equilibrium conditions can take place and is not inconsistent with conservation...

The intrinsic length scales of a reaction diffusion system (Gierer-Meinhardt model) is varied by quasi-statically changing the diffusion constant of the activator and a transition from rolls to hexagon is detected. The transition is hysteretic or first order like. From stability analysis, we...

We look at the dynamics of a Brownian particle with internal degrees of freedom and conformation dependent damping. Inhomogeneous damping apparently makes the problem a stochastic process with multiplicative noise. We derive the equilibrium distribution of such a system on the basis of a single...

We present a general stochastic forest-fire model which shows a variety of different structures depending on the parameter values. The model contains three possible states per site (tree, burning tree, empty site) and three parameters (tree growth probability p, lightning probability f, and...

A forest-fire model is introduced which contains a lightning probability f. This leads to a self-organized critical state in the limit f→0 provided that the time scales of free growth and burning down of forest clusters are separated. We derive scaling laws and calculate all critical...

We present a generalization of the forest-fire model of P. Bak et al. by including the immunity g which is the probability that a tree is not ignited although one of its neighbors is burning. When g reaches a critical value gc(p), which depends on the tree growth rate p, the fire cannot survive...

We study the influence of the type of update functions on the evolution of Boolean networks under selection for dynamical robustness. The chosen types of functions are canalyzing functions and threshold functions. Starting from a random initial network, we evolve the network by an adaptive walk....