We present generalized dynamical models describing the sharing of information, and the corresponding herd behavior, in a population based on the recent model proposed by Egúıluz and Zimmermann (EZ) [Phys. Rev. Lett. 85, 5659 (2000)]. The EZ model, which is a dynamical version of the herd formation model of Cont and Bouchaud (CB), gives a reasonable model for the formation of clusters of agents ...

I propose a modification of the spherical infall model for the evolution of density fluctuations with initially Gaussian probability distribution and scale-free power spectra. I introduce a generalized form of the initial density distribution around an overdense region and cut it off at half the inter-peak separation accounting in this way for the presence of neighbouring fluctuations. Contrary...

We study, both analytically and numerically, an ARCH-like, multiscale model of volatility, which assumes that the volatility is governed by the observed past price changes over different time scales. With a power-law distribution of time horizons, we obtain a model that captures most stylized facts of financial time series: Student-like distribution of returns with a power-law tail, long-memory...

Generalized statistical models of voids and hierarchical structure in cosmology are developed. The often quoted negative binomial model and the frequently used thermodynamic model are shown to be special cases of a more general distribution that contains a parameter a. This parameter is related to the Lévy index and the Fisher critical exponent , the latter of which describes the power-law fall...

In this paper we explore whether violence in Iraq is gravitating towards a steady state level of violence observed in other civil wars, such as those in Colombia, Sri Lanka, Sierra Leone, among others. Using data from the Iraq Body Count for 2003-2007, we explore whether civilian casualties follow a power law distribution. We replicate previous analyses of civilian casualties and confirm that c...

I propose a modification of the spherical infall model for the evolution of density fluctuations with initially Gaussian probability distribution and scale-free power spectra in Einstein-de Sitter universe as developed by Hoffman & Shaham. I introduce a generalized form of the initial density distribution around an overdense region and cut it off at half the inter-peak separation accounting in ...

Allometric growth is found in many tagging systems online. That is, the number of new tags (T ) is a power law function of the active population (P ), or T ∼ P γ (γ 6= 1). According to previous studies, it is the heterogeneity in individual tagging behavior that gives rise to allometric growth. These studies consider the power-law distribution model with an exponent β, regarding 1/β as an index...

In discrete contexts such as the degree distribution for a graph, scale-free has traditionally been defined to be power-law. We propose a reasonable interpretation of scale-free, namely, invariance under the transformation of p-thinning, followed by conditioning on being positive. For each β ∈ (1, 2), we show that there is a unique distribution which is a fixed point of this transformation; the...

The paper deals with a Doubly Fed Induction Machine (DFIM). It presents a study of an active power distribution law between stator and rotor sides. The DFIM is supplied by two voltages PWM inverters in stator and rotor. The power distribution law imposes a relation between rotoric and statoric pulsations. Due to this relation, a new variation structure of the DFIM speed control is presented. Th...