A model of telomere dynamics is proposed and examined. Our model, which extends a previously introduced model that incorporates stem cells as progenitors of new cells, imposes the Hayflick limit, the maximum number of cell divisions that are possible. This new model leads to cell populations for...

In Penna's model for biological ageing we reduce after equilibration the influence of acquired diseases and get, similar to reality, the observed increase of the Gompertz slope for the human mortality curves.

We review the results obtained using the Penna model for biological ageing (T.J.P. Penna, J. Stat. Phys. 78 (1995) 1629) when different strategies of parental care are introduced into evolving populations. These results concern to: longevity of semelparous populations; self-organization of...

We have analyzed the possibility of scaling the sexual Penna ageing model. Assuming that the number of genes expressed before the reproduction age grows linearly with the genome size and that the mutation rate per genome and generation is constant, we have found that the fraction of defective...

In nature, the process of sexual reproduction is found to be much more prevalent than the other processes of reproduction. To justify this preference, we present here a model for computer simulation of the process of survival in a colony of organisms, taking into account food and space...

This article is an empirical evaluation of the choice of fixed cutoff points in assessing the root mean square error of approximation (RMSEA) test statistic as a measure of goodness-of-fit in Structural Equation Models. Using simulation data, the authors first examine whether there is any...

Computer modelling for evolutionary systems consists in: (1) to store in the memory the individual features of each member of a large population; and (2) to update the whole system repeatedly, as time goes by, according to some prescribed rules (reproduction, death, ageing, etc.) where some...

The extended XY-model, a classical system of planar rotators with nearest neighbor interaction, is studied with molecular dynamics simulations. This model exhibits a first-order phase transition between a low-temperature phase with algebraic decay of spatial correlations and a high-temperature...