arXiv subjects
Publications and source records attributed to M. Bezzi.
We present a simple model based on a reaction-diffusion equation to explain pattern formation in a multicellular bacterium (Streptomyces). We assume competition for resources as the basic mechanism that leads to pattern formation; in particular we are able to reproduce the spatial pattern formed by bacterial aerial mycelium in case of growth in minimal (low resources) and maximal (large resources) culture media.
We introduce a toy model for interacting populations connected by mutations and limited by a shared resource. We study the presence of Eigen's error threshold and mutational meltdown. The phase diagram of the system shows that the extinction of the whole population due to mutational meltdown can occur well before an eventual error threshold transition.
A deterministic cellular automaton rule defined on the Moore neighbourhood is studied as a model of epidemic propagation. The directed nature of the interaction between cells allows one to introduce the dependence on a disorder parameter that determines the fraction of ``in-phase'' cells. Phase-disorder is shown to produce peculiar changes in the dynamical and statistical properties of the different evolution regimes obtained by varying the infection and the immunization periods. In particular, the finite-velocity spreading of perturbations, characterizing chaotic evolution, can be prevented by localization effects induced by phase-disorder, that may also yield spatial isotropy of the infection propagation as a statistical effect. Analogously, the structure of phase-synchronous ordered patterns is rapidly lost as soon as phase-disorder is increased, yielding a defect-mediated turbulent regime.