Biomedical subjects

F G Brady Moreira

Publications and source records attributed to F G Brady Moreira.

5 recordsLinked to original sources

PubMed2006

Domain motion in the voter model with noise.

We study the voter model with noise on one-dimensional chains using Monte Carlo simulations and finite-size scaling techniques. We observe that the system evolution toward consensus is deeply affected by the addition of noise, and that the time to reach complete ordering increases with the noise parameter q. In particular, the simulations show that the average domain size scales as xi approximately q(-1/2) whereas the magnetization scales with the number of nodes as m approximately N(-1/2).

Journal Article↗

PubMed2005

Adaptive walk on complex networks.

We investigate the properties of adaptive walks on an uncorrelated fitness landscape which is established in sequence spaces of complex structure. In particular, we perform numerical simulations of adaptive walks on random graphs and scale-free networks. For the former, we also derive some analytical approximations for the density of local optima of the fitness landscape and the mean length walk. We compare our results with those obtained for regular lattices. We obtain that the density of local optima decreases as 1/z, where z is the mean connectivity, for all networks we have investigated. In random graphs, the mean length walk L reaches the asymptotic value e - 1 for large z, which corresponds to the result for regular networks. Although we could not find an exact estimate, we derive an underestimated value for L. Unlike random graphs, scale-free networks show an upper asymptotic value of L.

Adaptation, Physiological↗

PubMed2005

Majority-vote model on random graphs.

The majority-vote model with noise on Erdös-Rényi's random graphs has been studied. Monte Carlo simulations were performed to characterize the order-disorder phase transition appearing in the system. We found that the value of the critical noise parameter qc is an increasing function of the mean connectivity z of the random graph. The critical exponents beta/nu, gamma/nu, and 1/nu were calculated for several values of z, and our analysis yielded critical exponents satisfying the hyperscaling relation with effective dimensionality equal to unity.

Journal Article↗

PubMed2003

Small-world effects in the majority-vote model.

We investigate the majority-vote model on small-world networks by rewiring the two-dimensional square lattice. We observe that the introduction of long-range interactions does not remove the critical character of the model, that is, the system still exhibits a well-defined phase transition. However, we find that now the critical point is a monotonically increasing function of the rewiring probability. Moreover, we find that small-world effects change the class of universality of the model.

Journal Article↗

PubMed1999

Tensile water transport in a porous gel.

A Monte Carlo simulation model, which incorporates the effect of tensile forces as well as diffusion, is proposed to explain the behavior of water transport in a saturated porous gel. The algorithm is able to account for the puzzling moisture profiles, which were first observed by conventional magnetic resonance imaging and, more recently, by Overhauser imaging.

Journal Article↗