Many natural systems, as social insects, perform complex computations collectively. In these groups, large numbers of individuals communicate in a local way and send information to its nearest neighbors. Interestingly, a general observation of these societies reveals that the computational...

Some authors have hypothesized that the observed self-synchronized activity in ant colonies provides some adaptive advantages, and, in particular, it has been suggested that task realization may benefit from this ordered temporal pattern of behavior (Robinson, 1992; Hatcher et al., 1992). In this...

Life has existed on the Earth for more than three billion years. Until the Cambrian explosion about 540 million years ago however, it was restricted mostly to single-celled micro-organisms that were, for the most part, poorly preserved in the fossil record. From the Cambrian explosion onwards,...

A model of biological morphogenesis is presented. The model is based in a gene-network cell description plus the interaction among cells. Here interactions between nearest cells are due to diffusion-like mechanisms and also to inductive, cell-to-cell interactions. The gene network properties are...

One of the most popular data sets in ecology, that of lynx fur returns, is analyzed in order to look for evidence for a bifurcation process. This bifurcation seems to be present from the observation of a shift in the amplitude of oscillations of the lynx time series. The possibility for such a...

A dynamical model of an ecological community is analyzed within a "mean-field approximation" in which one of the species interacts with the combination of all of the other species in the community. Within this approximation the model may be formulated as a master equation describing a one-step...

In a recent study, Ohira and Sawatari presented a simple model of computer network traffic dynamics. These authors showed that a phase transition point is present separating the low-traffic phase with no congestion from the congestion phase as the packet creation rate increases. We further...

A new model ecosystem consisting of many interacting species is introduced. The species are connected through a random matrix with a given connectivity . It is shown that the system is organized close to a boundary of marginal stability in such a way that fluctuations follow power law...

Many complex systems can be described in terms of networks of interacting units. Recent studies have shown that a wide class of both natural and artificial nets display a surprisingly widespread feature: the presence of highly heterogeneous distributions of links, providing an extraordinary...

The topology of the proteome map revealed by recent large-scale hybridization methods has shown that the distribution of protein-protein interactions is highly heterogeneous, with many proteins having few links while a few of them are heavily connected. This particular topology is shared by...