Thermal Gradient Changes Caused by Water in the Soil

The heat flow density data published in the Geothermal Atlas of Europe (1992) show relatively high values for temperature gradients measured in holes in the SW area (Portugal and Spain) of the Iberian Peninsula. This study tries to explain this fact based in the presence of water at relatively high temperatures outside the holes where the measurements were made, and the inclination of strata, derived from samples taken from the boreholes. We used a two-dimensional numerical model based on the finite volume method. Equations governing the transfer of energy by conduction and advection and fluid flow, were solved. Thermal conductivity values of the rocks and water may vary spatially as well as the porosity. Thermal conductivity values were measured but values of the hydraulic conductivity and porosity are unknown. Due to this fact, the models are tested with different values of these parameters. The heat flow density value considered for the region is 60 mWm-2 and the thermal gradient is calculated using the value of thermal conductivity. The results obtained with the models are compared with those published. Different solutions can be obtained for a given hole

Comment on "Spin-1 aggregation model in one dimension"

M. Girardi and W. Figueiredo have proposed a simple model of aggregation in one dimension to mimic the self-assembly of amphiphiles in aqueous solution [Phys. Rev. E 62, 8344 (2000)]. We point out that interesting results can be obtained if a different set of interactions is considered, instead of their choice (the s=1 Ising model).Comment: Accepted for publication in Phys. Rev.

On a nonlocal degenerate parabolic problem

Conditions for the existence and uniqueness of weak solutions for a class of nonlinear nonlocal degenerate parabolic equations are established. The asymptotic behaviour of the solutions as time tends to infinity are also studied. In particular, the finite time extinction and polynomial decay properties are proved

Nutritional status and socioeconomic change among Toba and Wichí populations of the Argentinean Chaco

The prevalence of overweight and obesity is growing at an accelerated pace in disadvantaged populations. Indigenous populations all over the world, whose lifestyle is changing rapidly and drastically, seem to be particularly prone to show an increased prevalence of overweight and its co-morbidities among adults. The aim of this study was to evaluate the association between socioeconomic and nutritional statuses in adults of two indigenous populations of the Argentine Gran Chaco: the Toba and Wichí of the province of Formosa. Originally hunter-gatherers, they are now more settled and engage in temporary wage labor and local political positions. A total of 541 adults (>20 years old) participated in the study. Almost 50% of the adult Toba and 34% of the adult Wichí were overweight and 10% of adults in both populations were obese. Socioeconomic status was positively associated with body mass index in both populations. Furthermore, political connectedness with the non-indigenous sector, as in the case of community leaders, was highly correlated with obesity. Differences within and between groups can be explained by biocultural factors that include gender, diet (foraged vs store-bought), lifestyle (sedentary vs more active), and history of political power. Our study highlights the interactions among social, cultural, and political economic variables, such as political hierarchies within the group or degree of social connectedness with community leaders. By making these variables an integral part of our analysis and interpretation, we hope to improve our understanding of the situation of indigenous populations in transition. © 2009 Elsevier B.V. All rights reserved.Fil: Valeggia, Claudia Rita. University of Pennsylvania; Estados UnidosFil: Burke, Kevin M.. University of Pennsylvania; Estados UnidosFil: Fernandez Duque, Eduardo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Centro de Ecología Aplicada del Litoral. Universidad Nacional del Nordeste. Centro de Ecología Aplicada del Litoral; Argentina. University of Pennsylvania; Estados Unido

Elimination of resonances in codimension one foliations

The problem of reduction of singularities for germs of codimension one foliations in dimension three has been solved by Cano in [3]. The author divides the proof in two steps. The first one consists in getting pre-simple points and the second one is the passage from pre-simple to simple points. In arbitrary dimension of the ambient space the problem is open. In this paper we solve the second step of the problem

Convergence of the Crank-Nicolson-Galerkin finite element method for a class of nonlocal parabolic systems with moving boundaries

The aim of this paper is to establish the convergence and error bounds to the fully discrete solution for a class of nonlinear systems of reaction-diffusion nonlocal type with moving boundaries, using a linearized Crank-Nicolson-Galerkin finite element method with polynomial approximations of any degree. A coordinate transformation which fixes the boundaries is used. Some numerical tests to compare our Matlab code with some existing moving finite elements methods are investigated