Self-organized criticality (SOC) has been claimed to play an important role in many natural and social systems. In the present work we empirically investigate the relevance of this theory to stock-market dynamics. Avalanches in stock-market indices are identified using a multi-scale...

The stock market is a complex self-interacting system, characterized by intermittent behaviour. Periods of high activity alternate with periods of relative calm. In the present work we investigate empirically the possibility that the market is in a self-organized critical state (SOC). A wavelet...

In the present work we extend the Bak–Sneppen model for biological evolution by introducing local interactions between species. This “environmental” perturbation modifies the intrinsic fitness of each element of the ecology, leading to higher survival probability, even for the less fit....

Recently, Abe and Suzuki pointed out that epicenters of earthquakes could be connected in order to generate a graph, with properties of a scale-free network. We have shown that the Olami–Feder–Christensen (OFC) model for the dynamics of earthquakes, defined both in square and cubic lattices,...

Unlike equilibrium systems, where it is possible to study the impact of endogenous and exogenous perturbations using fluctuation-dissipation theorems, it is difficult to understand and predict the impact of shocks in out-of-equilibrium systems. This thesis tries to uncover and quantify the...