Simón Bolívar University

About: Simón Bolívar University is a education organization based out in Caracas, Venezuela. It is known for research contribution in the topics: Population & Crystallization. The organization has 5912 authors who have published 8294 publications receiving 126152 citations.

Restoration of coral populations in light of genetic diversity estimates

Abstract: Due to the importance of preserving the genetic integrity of populations, strategies to restore damaged coral reefs should attempt to retain the allelic diversity of the disturbed population; however, genetic diversity estimates are not available for most coral populations. To provide a generalized estimate of genetic diversity (in terms of allelic richness) of scleractinian coral populations, the literature was surveyed for studies describing the genetic structure of coral populations using microsatellites. The mean number of alleles per locus across 72 surveyed scleractinian coral populations was 8.27 (±0.75 SE). In addition, population genetic datasets from four species (Acropora palmata, Montastraea cavernosa, Montastraea faveolata and Pocillopora damicornis) were analyzed to assess the minimum number of donor colonies required to retain specific proportions of the genetic diversity of the population. Rarefaction analysis of the population genetic datasets indicated that using 10 donor colonies randomly sampled from the original population would retain >50% of the allelic diversity, while 35 colonies would retain >90% of the original diversity. In general, scleractinian coral populations are genetically diverse and restoration methods utilizing few clonal genotypes to re-populate a reef will diminish the genetic integrity of the population. Coral restoration strategies using 10–35 randomly selected local donor colonies will retain at least 50–90% of the genetic diversity of the original population.

El burnout académico: delimitación del síndrome y factores asociados con su aparición

Abstract: El articulo presenta una revision de los principales conceptos del sindrome de burnout academico, su evolucion y su delimitacion conceptual con otros trastornos como depresion y ansiedad, asi como tambien una revision de los modelos teoricos del burnout en el ambito laboral para su aplicacion en el ambito academico. Ademas, se contextualizan las variables asociadas a su desarrollo y sus consecuencias en el rendimiento academico y en la salud mental de estudiantes universitarios.

Thermodynamic Studies of Anion Adsorption at Stepped Platinum(hkl) Electrode Surfaces in Sulfuric Acid Solutions

Abstract: The thermodynamics of the so-called perfectly polarized electrode was employed to analyze the total charge densities for stepped Pt(hkl) electrodes in solutions of H2SO4 with an excess of an inert electrolyte (0.1 M HClO4). Three Pt single-crystal electrodesPt(10,10,9) = 20(111)×(111), Pt(7,7,6) = 14(111)×(111), and Pt(5,5,4) = 10(111)×(111)vicinal to the Pt(111) surface were employed in these studies. A complete thermodynamic analysis using the electrode potential and the charge as independent variables has been performed. The Gibbs excess, Gibbs energy of adsorption, electrosorption valency, and Esin−Markov coefficients for (bi)sulfate adsorption at these surfaces have been determined. The thermodynamic data display a dependence on the crystallographic structure of the Pt electrode surface. Both the Gibbs excess and the Gibbs energy of adsorption decrease with increasing step density or decreasing terrace length. This result indicates that adsorption of (bi)sulfate is stronger at larger (111) terraces.

LP-based heuristics for cost-optimal planning

Abstract: Many heuristics for cost-optimal planning are based on linear programming. We cover several interesting heuristics of this type by a common framework that fixes the objective function of the linear program. Within the framework, constraints from different heuristics can be combined in one heuristic estimate which dominates the maximum of the component heuristics. Different heuristics of the framework can be compared on the basis of their constraints. With this new method of analysis, we show dominance of the recent LP-based state-equation heuristic over optimal cost partitioning on single-variable abstractions. We also show that the previously suggested extension of the state-equation heuristic to exploit safe variables cannot lead to an improved heuristic estimate. We experimentally evaluate the potential of the proposed framework on an extensive suite of benchmark tasks.