Biomedical subjects

F van Wijland

Publications and source records attributed to F van Wijland.

3 recordsLinked to original sources

PubMed2005

Chaotic properties of systems with Markov dynamics.

We present a general approach for computing the dynamic partition function of a continuous-time Markov process. The Ruelle topological pressure is identified with the large deviation function of a physical observable. We construct for the first time a corresponding finite Kolmogorov-Sinai entropy for these processes. Then, as an example, the latter is computed for a symmetric exclusion process. We further present the first exact calculation of the topological pressure for an N-body stochastic interacting system, namely, an infinite-range Ising model endowed with spin-flip dynamics. Expressions for the Kolmogorov-Sinai and the topological entropies follow.

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PubMed2003

Magnetization distribution in the transverse Ising chain with energy flux.

The zero-temperature transverse Ising chain carrying an energy flux j(E) is studied with the aim of determining the nonequilibrium distribution functions, P(M(z)) and P(Mx) of its transverse and longitudinal magnetizations, respectively. An exact calculation reveals that P(M(z)) is a Gaussian both at j(E)=0 and at j(E) not equal to 0, and the width of the distribution decreases with increasing energy flux. The distribution of the order-parameter fluctuations, P(Mx), is evaluated numerically for spin chains of up to 20 spins. For the equilibrium case (j(E)=0), we find the expected Gaussian fluctuations away from the critical point, while the critical order-parameter fluctuations are shown to be non-Gaussian with a scaling function Phi(x)=Phi(M(x)/ )= P(Mx) strongly dependent on the boundary conditions. When j(E) not equal to 0, the system displays long-range, oscillating correlations but P(Mx) is a Gaussian nevertheless, and the width of the Gaussian decreases with increasing j(E). In particular, we find that, at critical transverse field, the width has a j(-3/8)(E) asymptotic in the j(E)-->0 limit.

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PubMed2001

Field theory for reaction-diffusion processes with hard-core particles.

We show how to build up a systematic bosonic field theory for a general reaction-diffusion process involving hard-core particles in arbitrary dimension. We discuss a recent approach proposed by Park, Kim, and Park [Phys. Rev. E 62, 7642 (2000)]. As a test bench for our method, we show how to recover the equivalence between asymmetric diffusion of excluding particles and the noisy Burgers equation.

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