Wealth redistribution with finite resources

We present a simplified model for the exploitation of finite resources by interacting agents, where each agent receives a random fraction of the available resources. An extremal dynamics ensures that the poorest agent has a chance to change its economic welfare. After a long transient, the system self-organizes into a critical state that maximizes the average performance of each participant. Our model exhibits a new kind of wealth condensation, where very few extremely rich agents are stable in time and the rest stays in the middle class.Comment: 4 pages, 3 figures, RevTeX 4 styl

Geochemical and geochronological constraints on the geologic evolution of the western Sonobari Complex, northwestern Mexico

In the southern Sierra Sonobari, NW Mexico, U-Pb and 40Ar/39Ar geochronology studies allowed to define the provenance and maximum depositional age of the Francisco Gneiss basement of the Sonobari terrane, and to establish the age of some magmatic events in that area. The youngest zircon cluster in paragneisses of the Francisco Gneiss indicates a maximum depositional age of 509 ± 29Ma. The main peaks of the relative probability plot yield ages of 1690 and 1404Ma with minor peaks at 1156, 921, and 517Ma. Major peaks suggest that the main source of sediments was the Paleo- and Mesoproterozoic crust of Laurentia. Orthogneiss from the Francisco Gneiss yields a U-Pb zircon upper intercept age of 248 ± 28Ma, which is interpreted as the crystallization age. Crosscutting dykes of metabasite yield an 40Ar/39Ar age of 67 ± 5Ma, which is interpreted as indicating cooling after either a latest Early Cretaceous orogenic event or Late Cretaceous contact metamorphism. Granodiorite intruding the Francisco Gneiss yields a U-Pb age of 64 ± 1Ma, which is interpreted as a magmatic age. The hornblende-plagioclase Macochin Gabbro yields 40Ar/39Ar isochron ages of 54 ± 10Ma and 47 ± 5Ma, which are interpreted as cooling ages after the gabbro intrusion. Geochemical data indicate that the mafic rocks of the Francisco Gneiss correspond to subalkaline basalts of tholeiitic affinity with concentrations of high field strength elements similar to oceanic basalts, suggesting an asthenospheric upper mantle source. However, according to the variation in Th/Yb and U/Yb, the amphibolites display a significant influence of the upper continental crust. The Macochin Gabbro also has a geochemical signature characteristic of subalkaline basalt with tholeiitic affinity, and high field strength elements similar to oceanic basalts. Tectonic discrimination diagrams and elemental distribution suggest that the mafic rocks of both the Francisco Gneiss and Macochin Gabbro were emplaced during rifting in a back-arc setting

Correlation between Risk Aversion and Wealth distribution

Different models of capital exchange among economic agents have been proposed recently trying to explain the emergence of Pareto's 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 posses different levels of risk aversion, going from uniform to a random distribution. In all cases the risk aversion level for a given agent is constant during the simulation. While for a 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.Comment: 8 pages, 7 figures, submitted to Physica A, Proceedings of the VIII LAWNP, Salvador, Brazil, 200

Genetic relationship of the marismeña cow with some andalusian breeds

The Marismeña breed has a large variety of coat colors, this fact could be explained by the influence of other Andalusian breeds like Pajuna, or Berrenda. The objective of this research work was to detect the influence of some different Andalusian bovine breeds into the Marismeña bovine population from Doñana National Park. For the DNA extraction blood samples were used from the races: (n=224) Marismeña (40), Berrenda en Colorado (40), Berrenda en Negro (32) y Pajuna (40); as control groups, Palmera (43) and Nelore (29). A 27 microsatellites battery applied in the European project of bovine breeds characterization was used in this work. Most of microsatellites were Hardy-Weinberg equilibrated, except Berrenda en Negro was found 11 in disequilibrium (p<0.01). The individual assignment was performed with Bayesian (Structure) method. Bayesian clustering for multiple-locus assignment to genetic groups indicated low levels of admixture in the Marismeña breed. Thus, the Marismeña breed may not be admixture with Pajuna, Berrenda en Negro or Berrenda en Colorado.La raza Marismeña es una de las razas con el color de capa más variado, incluye desde los colores sólidos hasta los berrendos. El objetivo de este trabajo fue detectar la influencia de algunas razas andaluzas en la población bovina Marismeña del Parque Nacional de Doñana. Se utilizó sangre para la extracción de ADN de animales de las razas (n): Marismeña (40), Berrenda en Colorado (40), Berrenda en Negro (32) y Pajuna (40); se manejaron como poblaciones control la Palmera (43) y la Nelore (29). Se utilizó una batería de 27 microsatélites que fueron aplicados en el proyecto europeo de caracterización de razas bovinas. La mayoría de los microsatélites se encontraron en equilibrio Hardy-Weinberg excepto la Berrenda en Negro que tuvo 11 en desequilibrio (p<0,01). Se realizó un análisis de asignación de los individuos a su población con el programa Structure versión 2.1. El análisis bayesiano para asignación multilocus indicó que la raza Marismeña es la que esta genéticamente mejor definida. Se analizaron valores de k (número de poblaciones) de 2 a 6. Se concluye que la raza Marismeña no tiene influencia de Pajuna o de las Berrendas

Self Excitation of the Tunneling Scalar Field in False Vacuum Decay

A method to determine the quantum state of a scalar field after $O(4)$-symmetric bubble nucleation has been developed recently. The method has an advantage that it concisely gives us a clear picture of the resultant quantum state. In particular, one may interpret the excitations as a particle creation phenomenon just as in the case of particle creation in curved spacetime. As an application, we investigate in detail the spectrum of quantum excitations of the tunneling field when it undergoes false vacuum decay. We consider a tunneling potential which is piece-wise quadratic, hence is simple enough to allow us an analytical treatment. We find a strong dependence of the excitation spectrum upon the shape of the potential on the true vacuum side. We then discuss features of the excitation spectrum common to general tunneling potentials not restricted to our simple model.Comment: 24 pages, uuencoded compressed postscript fil

Vector Bin Packing with Multiple-Choice

We consider a variant of bin packing called multiple-choice vector bin packing. In this problem we are given a set of items, where each item can be selected in one of several $D$-dimensional incarnations. We are also given $T$ bin types, each with its own cost and $D$-dimensional size. Our goal is to pack the items in a set of bins of minimum overall cost. The problem is motivated by scheduling in networks with guaranteed quality of service (QoS), but due to its general formulation it has many other applications as well. We present an approximation algorithm that is guaranteed to produce a solution whose cost is about $\ln D$ times the optimum. For the running time to be polynomial we require $D=O(1)$ and $T=O(\log n)$. This extends previous results for vector bin packing, in which each item has a single incarnation and there is only one bin type. To obtain our result we also present a PTAS for the multiple-choice version of multidimensional knapsack, where we are given only one bin and the goal is to pack a maximum weight set of (incarnations of) items in that bin

Estudio Integral sobre la Evaluación del Recurso Eólico en Entornos Urbanos. Estación Anemométrica Adaptable

Como consecuencia de un intenso proceso de trabajo, coordinado con Investigadores del CIEMAT (Centro de Investigaciones Energéticas, Medioambientales y Tecnológicas), se pretende comunicar el estado del trabajo de Investigación relacionado con la Evaluación del Potencial Eólico en entornos urbanos, con vistas a la posible generación de energía eléctrica limpia

Boson-fermion unification, superstrings, and Bohmian mechanics

Bosonic and fermionic particle currents can be introduced in a more unified way, with the cost of introducing a preferred spacetime foliation. Such a unified treatment of bosons and fermions naturally emerges from an analogous superstring current, showing that the preferred spacetime foliation appears only at the level of effective field theory, not at the fundamental superstring level. The existence of the preferred spacetime foliation allows an objective definition of particles associated with quantum field theory in curved spacetime. Such an objective definition of particles makes the Bohmian interpretation of particle quantum mechanics more appealing. The superstring current allows a consistent Bohmian interpretation of superstrings themselves, including a Bohmian description of string creation and destruction in terms of string splitting. The Bohmian equations of motion and the corresponding probabilistic predictions are fully relativistic covariant and do not depend on the preferred foliation.Comment: 30 pages, 1 figure, revised, to appear in Found. Phy

Confirmation of Anomalous Dynamical Arrest in attractive colloids: a molecular dynamics study

Previous theoretical, along with early simulation and experimental, studies have indicated that particles with a short-ranged attraction exhibit a range of new dynamical arrest phenomena. These include very pronounced reentrance in the dynamical arrest curve, a logarithmic singularity in the density correlation functions, and the existence of `attractive' and `repulsive' glasses. Here we carry out extensive molecular dynamics calculations on dense systems interacting via a square-well potential. This is one of the simplest systems with the required properties, and may be regarded as canonical for interpreting the phase diagram, and now also the dynamical arrest. We confirm the theoretical predictions for re-entrance, logarithmic singularity, and give the first direct evidence of the coexistence, independent of theory, of the two coexisting glasses. We now regard the previous predictions of these phenomena as having been established.Comment: 15 pages,15 figures; submitted to Phys. Rev.

Experimental study of heat transfer and pressure drop in micro-channel based heat sinks with tip clearance

This article presents an experimental study on the optimisation of micro-heat sink configurations when both thermal effects and pressure drop are accounted for. The interest of the latter is that the practical engineering viability of some of these systems also depends on the required pumping power. The working fluid was water and, according to typical power dissipation and system size requirements, the considered fluid regime was either laminar or transitional, and not fully developed from the hydrodynamics point of view. Five configurations were considered: a reference geometry (selected for comparison purposes) made up of square section micro-channels, and four alternative configurations that involved the presence of a variable tip clearance in the design. The performance of the different configurations was compared with regard to both cooling efficiency and pressure drop. Finally, we also provide some practical guidelines for the engineering design of these types of systems