N. G. F. de Medeiros | Searcharxiv

arXiv1999

The influence of the Wolff's cluster structure on the determination of the critical dynamic exponent

Recently we reported some interesting features of the Wolff's algorithm behavior when applied to the site-bond-correlated Ising model.Our main results were that a stronger correlation diminishes the autocorrelation time but it does not change or affectthe critical dynamic exponent.In this paper, we analyse the Wolff's cluster structure and how it varies with the spatial correlation. The fractal dimensions are determined for several values of the magnetic atoms concentration and spacial correlation, giving an estimative of the critical dynamic exponent.

cond-mat.stat-mech↗

arXiv1999

Exact Solution of an Evolutionary Model without Ageing

We introduce an age-structured asexual population model containing all the relevant features of evolutionary ageing theories. Beneficial as well as deleterious mutations, heredity and arbitrary fecundity are present and managed by natural selection. An exact solution without ageing is found. We show that fertility is associated with generalized forms of the Fibonacci sequence, while mutations and natural selection are merged into an integral equation which is solved by Fourier series. Average survival probabilities and Malthusian growth exponents are calculated indicating that the system may exhibit mutational meltdown. The relevance of the model in the context of fissile reproduction groups as many protozoa and coelenterates is discussed.

cond-mat.stat-mech↗