Evaluación de los efectos de la urbanización en los arroyos de Tierra del Fuego

We set out to understand how urbanization affects streams in Ushuaia, Tierra del Fuego. Paired ttestsand linear regressions were used to compare physico-chemical stream habitat variables (i.e., temperature,turbidity, conductivity, dissolved oxygen and pH) and benthic macroinvertebrate community structure (i.e.,density, taxonomic richness, Shannon-Weiner diversity) and function (functional feeding groups [FFG]) in fourwatersheds with urban and reference sites. We then calculated indices of biotic integrity for habitat (rapid visualassessment protocol [RVAP]) and benthos (Ephemeroptera, Plecoptera, Trichoptera richness [EPT], family bioticindex [FBI], rapid bioassessment protocol [RBP] and biotic monitoring Patagonian streams [BMPS]). Resultsindicated that urbanization negatively impacted these streams? underlying ecological condition, decreasingbenthic biodiversity and dissolved oxygen, while increasing conductivity and turbidity. FFG assemblagewas similar between both sites, but urbanization increased the existing dominance of collector-gatherers.Additionally, urban sites presented lower values in three of the benthic macroinvertebrate indices (EPT, RBP,BMPS, but not FBI) and also for habitat (RVAP). These data fill an existing gap in stream ecology for southernPatagonia and are useful to create monitoring tools. By incorporating urbanization as a driver of ecosystemchange, managers and planners will be better able to confront the issue of sustainable development in thisregion, which is considered one of the most pristine wilderness areas remaining on the planet but whosehuman population is concentrated in a few densely populated urban areas.Fil: Zagarola, Jean Paul A.. Bonneville Environmental Foundation; Estados UnidosFil: Martínez Pastur, Guillermo José. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas; ArgentinaFil: Lopez, María Eugenia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas; ArgentinaFil: Anderson, Christopher Brian. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas; Argentin

Symmetry energy and the Pauli exclusion principle

In this article we present a classical potential that respects the Pauli exclusion principle and can be used to describe nucleon-nucleon interactions at intermediate energies. The potential depends on the relative momentum of the colliding nucleons and reduces interactions at low momentum transfer mimicking the Pauli exclusion principle. We use the potential with Metropolis Monte Carlo methods and study the formation of finite nuclei and infinite systems. We find good agreement in terms of the binding energies, radii, and internal nucleon distribution of finite nuclei, and the binding energy in nuclear matter and neutron star matter, as well as the formation of nuclear pastas, and the symmetry energy of neutron star matter.Fil: Dorso, Claudio Oscar. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Física de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Física de Buenos Aires; ArgentinaFil: Frank, Guillermo Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Tecnológica Nacional. Facultad Regional Buenos Aires. Unidad de Investigación y Desarrollo de las Ingenierías; ArgentinaFil: Lopez, Jorge A.. University of Texas at El Paso; Estados Unido

Exploiting graphic processing units parallelism to improve intelligent data acquisition system performance in JET's correlation reflectometer

The performance of intelligent data acquisition systems relies heavily on their processing capabilities and local bus bandwidth, especially in applications with high sample rates or high number of channels. This is the case of the self adaptive sampling rate data acquisition system installed as a pilot experiment in KG8B correlation reflectometer at JET. The system, which is based on the ITMS platform, continuously adapts the sample rate during the acquisition depending on the signal bandwidth. In order to do so it must transfer acquired data to a memory buffer in the host processor and run heavy computational algorithms for each data block. The processing capabilities of the host CPU and the bandwidth of the PXI bus limit the maximum sample rate that can be achieved, therefore limiting the maximum bandwidth of the phenomena that can be studied. Graphic processing units (GPU) are becoming an alternative for speeding up compute intensive kernels of scientific, imaging and simulation applications. However, integrating this technology into data acquisition systems is not a straight forward step, not to mention exploiting their parallelism efficiently. This paper discusses the use of GPUs with new high speed data bus interfaces to improve the performance of the self adaptive sampling rate data acquisition system installed on JET. Integration issues are discussed and performance evaluations are presente

A Linear Time Algorithm for Counting #2SAT on Series-Parallel Formulas

Capítulo de libroAn O(m + n) time algorithm is presented for counting the number of models of a two Conjunctive Normal Form Boolean Formula whose constrained graph is represented by a Series-Parallel graph, where n is the number of variables and m is the number of clauses. To the best of our knowledge, no linear time algorithm has been developed for counting in this kind of formulas

Contact inhibition of locomotion and mechanical cross-talk between cell-cell and cell-substrate adhesion determines the pattern of junctional tension in epithelial cell aggregates

We generated a computational approach to analyze the biomechanics of epithelial cell aggregates, either island or stripes or entire monolayers, that combines both vertex and contact-inhibition-of-locomotion models to include both cell-cell and cell-substrate adhesion. Examination of the distribution of cell protrusions (adhesion to the substrate) in the model predicted high order profiles of cell organization that agree with those previously seen experimentally. Cells acquired an asymmetric distribution of basal protrusions, traction forces and apical aspect ratios that decreased when moving from the edge to the island center. Our in silico analysis also showed that tension on cell-cell junctions and apical stress is not homogeneous across the island. Instead, these parameters are higher at the island center and scales up with island size, which we confirmed experimentally using laser ablation assays and immunofluorescence. Without formally being a 3-dimensional model, our approach has the minimal elements necessary to reproduce the distribution of cellular forces and mechanical crosstalk as well as distribution of principal stress in cells within epithelial cell aggregates. By making experimental testable predictions, our approach would benefit the mechanical analysis of epithelial tissues, especially when local changes in cell-cell and/or cell-substrate adhesion drive collective cell behavior.Comment: 39 pages, 8 Figures. Supplementary Information is include

Reproductibilidad de un cuestionario que valora la actividad física en adolescentes escolares

Introducción: Los cuestionarios de actividad física por lo general son los instrumentos más sencillos y fáciles de aplicar a grandes poblaciones, sin embargo, la capacidad de reproductibilidad varía entre las poblaciones. Objetivo: Analizar la fiabilidad de un cuestionario que valora la Actividad Física en una muestra de escolares adolescentes que viven a elevada altitud por medio de consistencia interna y test re-test. Diseño: Descriptivo-Transversal (Survey). Institución: Universidad Nacional del Altiplano, Puno, Perú. Participantes: Adolescentes escolares de 12 a 17 años. Intervenciones: Fueron seleccionados de forma sistemática 109 escolares de ambos sexos. Se valoró las medidas antropométricas de peso, estatura, estatura sentada y circunferencia del abdomen. Además se aplicó un cuestionario de actividad física con 11 preguntas (test y re-test) con un intervalo de 7 días. Principales medidas: Valoración de la capacidad de reproductibilidad por consistencia interna y estabilidad. Resultados: Los valores de alpha de Cronbach (Consistencia interna) mostraron valores de 0,73 a 0,77 para ambos sexos. El Error Técnico de Medida (ETM) fue de 0,50 a 1,61% y el coeficiente de correlación de Spearman  osciló entre 0,91 a 0,95. Conclusión: El cuestionario de actividad física muestra altos valores de confiabilidad, tanto en su consistencia interna como en la estabilidad de las medidas. Introduction: Physical activity questionnaires usually are the most simple and easy to apply to large populations, however, reproducibility capacity varies between populations. Objective: To analyze the reliability of a questionnaire to assess physical activity in a sample of school adolescents living at high altitude through internal consistency and test re-test. Design: Descriptive, transversal (Survey). Institution: Universidad Nacional del Altiplano, Puno, Peru. Participants: School Teens 12 to 17 years. Interventions: There were systematically selected 109 students of both sexes. We evaluated anthropometric measurements of weight, height, sitting height and circumference of the abdomen. In addition we applied a physical activity questionnaire with 11 questions (test and re-test) with an interval of 7 days. Main measures: capacity rating for internal consistency, reproducibility and stability. Results: Cronbach's alpha values ??(internal consistency) showed values ??from 0.73 to 0.77 for both sexes. Measuring technical error (SEM) was from 0.50 to 1.61% and the Spearman correlation coefficient ranges from 0.91 to 0.95. Conclusion: The physical activity questionnaire shows high values ??of reliability, consistency both internally and in the stability of the measures

A Keck/HIRES Doppler Search for Planets Orbiting Metal-Poor Dwarfs. I. Testing Giant Planet Formation and Migration Scenarios

We describe a high-precision Doppler search for giant planets orbiting a well-defined sample of metal-poor dwarfs in the field. This experiment constitutes a fundamental test of theoretical predictions which will help discriminate between proposed giant planet formation and migration models. We present here details on the survey as well as an overall assessment of the quality of our measurements, making use of the results for the stars that show no significant velocity variation.Comment: 25 pages, 7 figures, accepted for publication in the Astrophysical Journa