Some real systems usually drive themselves into a critical state. These systems are said to be in a state of selforganized criticality [1]. The theory of self-organized criticality aims to describe interactive, dissipative and self sustaining systems with many degrees of freedom. Hence it complements the chaos concept. These systems are characterized by power law statistics. Self-organized crit...

We investigate a renormalization group (RG) scheme for avalanche automata introduced recently by Pietronero et al. to explain universality in self-organized criticality models. Using a modified approach, we construct exact RG equations Ibr a one-dimensional model whose detailed dynamics is exactly solvable. We then investigate in detail the effect of approximations inherent in a practical imple...

We numerically study the piles generated by continuously dropping a particle on the top of a stable pile in (I + I) dimension. We use a code which has an implementation of static friction in the Molecular Dynamics (MD) simulations of granular material. We study several properties of the pile-the time evolution of mass and slope, and the avalanche size (and duration) distribution. We also study ...

The tasks of neural computation are remarkably diverse. To function optimally, neuronal networks have been hypothesized to operate near a nonequilibrium critical point. However, experimental evidence for critical dynamics has been inconclusive. Here, we show that the dynamics of cultured cortical networks are critical. We analyze neuronal network data collected at the individual neuron level us...

We consider two classes of threshold failure models, Abelian avalanches and sandpiles, with the redistribution matrices satisfying natural conditions guaranteeing absence of infinite avalanches. We investigate combinatorial structure of the set of recurrent configurations for these models and the corresponding statistical properties of the distribution of avalanches. We introduce reduction oper...

Using numerical simulations, we examine the dynamics of active matter run-and-tumble disks moving in a disordered array of obstacles. As a function of increasing active disk density and activity, we find a transition from a completely clogged state to a continuous flowing phase, and in the large activity limit, we observe an intermittent state where the motion occurs in avalanches that are powe...

Self-organized criticality 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 wavelet-filtering analysis designed to remove Gaussian noise from the index. Here new methods are developed to identify...

We report experimental measurements of avalanche behavior of thin granular layers on an inclined plane for low volume flow rate. The dynamical properties of avalanches were quantitatively and qualitatively different for smooth glass beads compared to irregular granular materials such as sand. Two scenarios for granular avalanches on an incline are identified, and a theoretical explanation for t...

Neural avalanches are a prominent form of brain activity characterized by network-wide bursts whose statistics follow a power-law distribution with a slope near 3/2. Recent work suggests that avalanches of different durations can be rescaled and thus collapsed together. This collapse mirrors work in statistical physics where it is proposed to form a signature of systems evolving in a critical s...

Previous studies have investigated the incidence of traumatic injury in avalanche victims. But the relationship between these injuries and the terrain that produces them remains largely unknown. The goal of this study was to examine the prevalence of traumatic injury among historical avalanche victims and to evaluate the correlation with terrain features generally regarded to be traps. An analy...