Critical exponents of the pair contact process with diffusion

We study the pair contact process with diffusion (PCPD) using Monte Carlo simulations, and concentrate on the decay of the particle density $\rho$ with time, near its critical point, which is assumed to follow $\rho(t) \approx ct^{-\delta} +c_2t^{-\delta_2}+...$. This model is known for its slow convergence to the asymptotic critical behavior; we therefore pay particular attention to finite-time corrections. We find that at the critical point, the ratio of $\rho$ and the pair density $\rho_p$ converges to a constant, indicating that both densities decay with the same powerlaw. We show that under the assumption $\delta_2 \approx 2 \delta$, two of the critical exponents of the PCPD model are $\delta = 0.165(10)$ and $\beta = 0.31(4)$, consistent with those of the directed percolation (DP) model

Random walk approach to the d-dimensional disordered Lorentz gas

A correlated random walk approach to diffusion is applied to the disordered nonoverlapping Lorentz gas. By invoking the Lu-Torquato theory for chord-length distributions in random media [J. Chem. Phys. 98, 6472 (1993)], an analytic expression for the diffusion constant in arbitrary number of dimensions d is obtained. The result corresponds to an Enskog-like correction to the Boltzmann prediction, being exact in the dilute limit, and better or nearly exact in comparison to renormalized kinetic theory predictions for all allowed densities in d=2,3. Extensive numerical simulations were also performed to elucidate the role of the approximations involved.Comment: 5 pages, 5 figure

It is Hobbes, not Rousseau:an experiment on voting and redistribution

We perform an experiment which provides a laboratory replica of some important features of the welfare state. In the experiment, all individuals in a group decide whether to make a costly effort, which produces a random (independent) outcome for each one of them. The group members then vote on whether to redistribute the resulting and commonly known total sum of earnings equally amongst themselves. This game has two equilibria, if played once. In one of them, all players make effort and there is little redistribution. In the other one, there is no effort and nothingWe thank Iris Bohnet, Tim Cason, David Cooper, John Duffy, Maia Guell, John Van Huyck and Robin Mason for helpful conversations and encouragement. The comments of the Editor and two referees helped improve the paper. We gratefully acknowledge the financial support from Spain’s Ministry of Science and Innovation under grants CONSOLIDER INGENIO 2010 CSD2006-0016 (all authors), ECO2009-10531 (Cabrales), ECO2008-01768 (Nagel) and the Comunidad de Madrid under grant Excelecon (Cabrales), the Generalitat de Catalunya and the CREA program (Nagel), and project SEJ2007-64340 of Spain’s Ministerio de Educación y Ciencia (Rodríguez Mora).Publicad

Diseño de un instrumento de caracterización de rasgos de personalidad en agresores sexuales

Especial InterésEl objetivo del instrumento es brindar una medida de los rasgos de personalidad predominantes en los agresores sexuales. Gracias a la revisión teórica y empírica, se identificó que se encuentran similitudes en sus rasgos de personalidad, a partir de los cuales se proponen 4 rasgos principales: Narcisista, Obsesivo Compulsivo, Antisocial y Límite de la personalidad. El cuestionario está compuesto por 35 ítems, de tipo dicotómico, que definen los 4 rasgos mencionados, dirigido a población penitenciaria condenada por delito de Agresión Sexual.RESUMEN 1. JUSTIFICACIÓN 2. MARCO LEGAL 3. MARCO ÉTICO 4. OBJETIVOS 5. PRODUCTO VISIBLE 6. ESTUDIO DE MERCADEO 7. El PRODUCTO RESULTADOS DISCUSIÓNPregradoPsicólog

Kramers-Kronig Relations For The Dielectric Function And The Static Conductivity Of Coulomb Systems

The mutual influence of singularities of the dielectric permittivity e(q,w) in a Coulomb system in two limiting cases w tends to zero, q tends to zero, and opposite q tends to zero, w tends to zero is established. It is shown that the dielectric permittivity e(q,w) satisfies the Kramers-Kronig relations, which possesses the singularity due to a finite value of the static conductivity. This singularity is associated with the long "tails" of the time correlation functions.Comment: 9 pages, 0 figure

Plasmas and Controlled Nuclear Fusion

Contains reports on three research projects.U. S. Atomic Energy Commission (Contract AT(11-1)-3070

Serum Heat Shock Protein 27 and Diabetes Complications in the EURODIAB Prospective Complications Study : A Novel Circulating Marker for Diabetic Neuropathy

OBJECTIVE—Heat shock protein 27 (HSP27) is a member of the small heat shock protein family of proteins. HSP27 expression is enhanced in target tissues of diabetic microvascular complications, and changes in circulating serum HSP27 levels (sHSP27) have been reported in patients with macrovascular disease. We investigated whether sHSP27 levels were associated with micro- and macrovascular complications in type 1 diabetic patients