Based on a recent model of shearing granular media we propose a new mechanism for slow dynamics. It consists of two main steps: A global optimization and a restructuring. We present numerical results of the model and its analytical treatment on the hierarchical lattice. A simplified local...

We introduce a simple lattice model for the formation and evolution of shear bands in granular media. We study this model by numerical simulations and find that due to the localization of the shear band and the consequent inhomogeneous aging of the material, the average density shows very...

We carried out computer simulations to study the green wave model (GWM), the parallel updating version of the two-dimensional traffic model of Biham et al. The better convergence properties of the GWM together with a multi-spin coding technique enabled us to extrapolate to the infinite system...

Many hypotheses have been proposed to explain why female birds start to incubate before clutch completion (IBCC). Some of those suggest that the resulting hatching asynchrony (HA) is adaptive because it increases the size hierarchy among offspring and in turn reduces nestling competition and...

Secondary sexual characters may have evolved in part to signal resistance to parasites. Avian song has been hypothesized to be involved in this process, but the role of parasites in modulating acoustic communication systems in birds remains largely unknown, owing to lack of experiments. We...

Stress may have consequences for the evolution of condition-dependent sexual traits. For example, stress may be related to sexual traits through immune function, and sexual traits can reflect how individuals bear the costs of stress-mediated immunosuppression. However, male traits may be...

The differential allocation hypothesis predicts that females invest more resources into reproduction when mating with attractive males. In oviparous animals this can include prefertilization decisions such as the production of larger eggs and the deposition of hormones, such as the steroid...

Yolk androgen deposition is a widely investigated maternal effect in birds, but its adaptive value is at present unclear. The offspring fitness correlates of natural yolk androgen levels are virtually unknown, whereas manipulations largely focused on testosterone and neglected other androgens....

In a polygynous mating system, females settling with already mated males often experience low mating success due to the reduced parental contribution of the male. However, there are numerous factors that may still make it advantageous for some females to choose this mating status. Facultative...