Sebastian Goncalves

Wealth redistribution in our small world

We present a simplified model for the exploitation of resources by interacting agents, in an economy with small-world properties. It is shown that Gaussian distributions of wealth, with some cutoff at a poverty line are present for all values of the parameters, while the frequency of maxima and minima strongly depends on the connectivity and the disorder of the lattice. Finally, we compare a system where the commercial links are frozen with an economy where agents can choose their commercial partners at each time step.

Correlation between risk aversion and wealth distribution

Different models of capital exchange among economic agents have been recently proposed trying to explain the emergence of Paretos wealth power-law distribution. One important factor to be considered is the existence of risk aversion. In this paper, we study a model where agents possess different levels of risk aversion, going from a uniform to a random distribution. In all cases the risk aversion level for a given agent is constant during the simulation. While for uniform and constant risk aversion the system self-organizes in a distribution that goes from an unfair “one takes all” distribution to a Gaussian one, a random risk aversion can produce distributions going from exponential to log-normal and power-law. Besides, interesting correlations between wealth and risk aversion are found.

Dynamics of thermal growth of silicon oxide films on Si

Thermal growth of silicon oxide films on Si in dry

Electronic versus phononic friction of xenon on silver

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Fast fragmentation of networks using module-based attacks

is modeled as a dynamical system, assuming that it is basically a reaction-diffusion phenomenon. Relevant findings of the last decade are incorporated, as structure and composition of the oxide/Si interface and

The dynamics of opinion in hierarchical organizations

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Bistability and hysteresis in the sliding friction of a dimer

transport and reaction at initial stages of growth. The present model departs from the well-established Deal and Grove framework [B. E. Deal and A. S. Grove, J. Appl. Phys. 36, 3770 (1965)] indicating that its basic assumptions, steady-state regime, and reaction between

Oscillations in SIRS model with distributed delays

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The social behavior and the evolution of sexually transmitted diseases

and Si at a sharp oxide/Si interface are only attained asymptotically. Scaling properties of these model equations are explored, and experimental growth kinetics, obtained for a wide range of growth parameters including the small thickness range, are shown to be well described by the model.

Why, when, and how fast innovations are adopted

Molecular dynamics simulations of a Xe monolayer sliding on Ag(001) and Ag(111) are carried out in order to ascertain the microscopic origin of friction. For several values of the electronic contribution to the friction of individual Xe atoms, the intra-overlayer phonon dissipation is calculated as a function of the corrugation amplitude of the substrate potential, which is a pertinent parameter to consider. Within the accuracy of the numerical results and the uncertainty with which the values of the relevant parameters are known at present, we conclude that electronic and phononic dissipation channels are of similar importance. While phonon friction gives rise to the rapid variation with coverage, the electronic friction provides a roughly coverage-independent contribution to the overall sliding friction.