Recently, it has been shown that the power spectrum of extinction intensity during the Phanerozoic takes a power-law form, which, it is suggested, may indicate the presence of critical phenomena in the dynamics underlying the extinction process. In this paper we reproduce these results using the...

Highly optimized tolerance is a model of optimization in engineered systems, which gives rise to power-law distributions of failure events in such systems. The archetypal example is the highly optimized forest fire model. Here we give an analytic solution for this model which explains the origin...

We introduce a new class of models in which a large number of "agents" organize under the influence of an externally imposed coherent noise. The model shows reorganization events whose size distribution closely follows a power-law over many decades, even in the case where the agents do not...

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...