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1 Abstract A generic model of stochastic autocatalytic dynamics with many de-The time evolution of the w i 's combines a random multiplicative dynamics w i (t + 1) = w i (t) at the individual level with a global coupling through a constraint which does not allow the w i 's to fall below a lower cutoo given by c w, where w is their momentary average and 0 <(More)
Statistical distributions with heavy tails are ubiquitous in natural and social phenomena. Since the entries in heavy tail have unproportional significance, the knowledge of its exact shape is very important. Citations of scientific papers form one of the best-known heavy tail distributions. Even in this case there is a considerable debate whether citation(More)
We tested human ability to recover the 3D structure and motion information from time-varying images where only 1D motion cues were available. Under these conditions, observers exhibit poor performance in discriminating between two perpendicular axes of rotation, or discriminating between rigid and non-rigid 3D motion. This behavior of the visual system is(More)
Recovering 3D information from a 2D time-varying image is a vital task which human observers face daily. Numerous models exist which compute global 3D structure and motion on the basis of 2D local motion measurements of point-like elements. On the other hand, both experimental and computational research of early visual motion mechanisms emphasize the role(More)
We study a few dynamical systems composed of many components whose sizes evolve according to multiplicative stochastic rules. We compare them with respect to the emergence of power laws in the size distribution of their components. We show that the details specifying and enforcing the smallest size of the components are crucial as well as the rules for(More)
Although computer viruses cause tremendous economic loss, defence mechanisms fail to adapt to their rapid evolution. Previous immunization strategies have been characterized as being static and centralized, which has made virus containment difficult or even impossible. We suggest, instead, to propagate the immunization agent as an epidemic. The main problem(More)
Power laws are found in a wide range of diierent systems: from sand piles to word occurrence frequencies and to the size distribution of cities. The natural emergence of these power laws in so many diierent systems, which has been called self organized criticality, seems rather mysterious and awaits a rigorous explanation. In this letter we study the(More)