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...

Extinction has been seldom considered as a relevant ingredient of neodarwinian theories. The fact, however, is that the number of species extinctions in the history of life is almost the same as the number of originations. The fossil record indicates that extinction events are patterned in some...

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...

Self-organizing maps (SOM) are unsupervised, competitive neural networks used to project high-dimensional data onto a low-dimensial space. In this article we show how SOM can be sued to draw graphs in the plane. The SOM-based approach to graph drawing, which belongs to the general class of...

In several species of ants, workers cooperate to retrieve large prey. Usually, one ant finds a prey item, tries to move it, and, when unsucessful for some time, recuits nestmates through direct contact or chemical marking. When a group of ants tries to move large prey, the ants change position...

Complex architectures grown by simple agents moving randomly on a 3D lattice and depositing bricks deterministically depending on local configurations of bricks are presented. Some of these architectures are strikingly similar to real wasp nest architectures. But most algorithms, in the space of...