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Van Den Berg T.L.,Aix - Marseille University | Fanelli D.,University of Florence | Fanelli D.,Centro Interdipartimentale per Lo Studio Delle Dinamiche Complesse | Fanelli D.,National Institute of Nuclear Physics, Italy | Leoncini X.,Aix - Marseille University
EPL | Year: 2010

The dynamics of many-body Hamiltonian systems with long-range interactions is studied, in the context of the so-called α-HMF model. Building on the analogy with the related mean-field model, we construct stationary states of the α-HMF model for which the spatial organization satisfies a fractional equation. At variance, the microscopic dynamics turns out to be regular and explicitly known. As a consequence, dynamical regularity is achieved at the price of strong spatial complexity, namely a microscopic inhomogeneity which locally displays scale invariance. © 2010 Europhysics Letters Association. Source

Burioni R.,University of Parma | Burioni R.,National Institute of Nuclear Physics, Italy | Di Santo S.,University of Parma | Di Volo M.,University of Parma | And 4 more authors.
Physical Review E - Statistical, Nonlinear, and Soft Matter Physics | Year: 2014

Self-organized quasiperiodicity is one of the most puzzling dynamical phases observed in systems of nonlinear coupled oscillators. The single dynamical units are not locked to the periodic mean field they produce, but they still feature a coherent behavior, through an unexplained complex form of correlation. We consider a class of leaky integrate-and-fire oscillators on random sparse and massive networks with dynamical synapses, featuring self-organized quasiperiodicity, and we show how complex collective oscillations arise from constructive interference of microscopic dynamics. In particular, we find a simple quantitative relationship between two relevant microscopic dynamical time scales and the macroscopic time scale of the global signal. We show that the proposed relation is a general property of collective oscillations, common to all the partially synchronous dynamical phases analyzed. We argue that an analogous mechanism could be at the origin of similar network dynamics. © 2014 American Physical Society. Source

Conversano C.,University of Pisa | Marazziti D.,University of Pisa | Carmassi C.,University of Pisa | Baldini S.,Normal School of Pisa | And 2 more authors.
Harvard Review of Psychiatry | Year: 2012

Pathological gambling is an emerging psychiatric disorder that has recently gained much attention because of its increasing prevalence and devastating personal, familial, and social consequences. Although its pathophysiology is largely unknown, the shared similarities with both addiction and obsessive-compulsive spectrum disorders have suggested the possibility of common psychobiological substrates. As with many other psychiatric disorders, it is believed that pathological gambling may result from the interplay between individual vulnerability and environmental factors. The aim of this article is to offer a comprehensive review of the main neurobiological aspects of pathological gambling, with particular attention to neuropsychological and related findings. A deeper understanding of the biological correlates of pathological gambling is required in order to develop effective treatment strategies. © 2012 President and Fellows of Harvard College. Source

Pini V.,CSIC - National Center of Microelectronics | Tiribilli B.,CNR Institute for Complex Systems | Tiribilli B.,Centro Interdipartimentale per Lo Studio Delle Dinamiche Complesse | Gambi C.M.C.,University of Florence | And 2 more authors.
Physical Review B - Condensed Matter and Materials Physics | Year: 2010

The detailed characterization of the dynamical behavior of an oscillating cantilever is a crucial task in many applications of scanning probe microscopy, force spectroscopy, and cantilever based biosensors. In the present work we considered a direct and localized excitation of the cantilever obtained using the photothermal effect induced by a modulated laser beam that allows us to completely separate the dynamics of the system from spurious effects. We developed a theoretical model able to describe the experimental results with high accuracy; in particular, a good agreement is achieved, both for amplitude and phase, in the presence of resonances and antiresonances, depending on the different location of the excitation beam. © 2010 The American Physical Society. Source

Di Volo M.,University of Parma | Di Volo M.,Centro Interdipartimentale per Lo Studio Delle Dinamiche Complesse | Di Volo M.,National Institute of Nuclear Physics, Italy | Burioni R.,University of Parma | And 9 more authors.
Physical Review E - Statistical, Nonlinear, and Soft Matter Physics | Year: 2014

We report about the main dynamical features of a model of leaky integrate-and-fire excitatory neurons with short-term plasticity defined on random massive networks. We investigate the dynamics by use of a heterogeneous mean-field formulation of the model that is able to reproduce dynamical phases characterized by the presence of quasisynchronous events. This formulation allows one to solve also the inverse problem of reconstructing the in-degree distribution for different network topologies from the knowledge of the global activity field. We study the robustness of this inversion procedure by providing numerical evidence that the in-degree distribution can be recovered also in the presence of noise and disorder in the external currents. Finally, we discuss the validity of the heterogeneous mean-field approach for sparse networks with a sufficiently large average in-degree. © 2014 American Physical Society. Source

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