University of Extremadura is a Spanish public university in Extremadura .It was founded in 1973 by Decree 991/1973, May 10 of the Ministry of Education and Science of Spain.Currently the University of Extremadura offers 64 Bachelor's Degrees and 32 Master's Degrees in many different fields of knowledge.Together with the University of Cantabria, Castilla-La Mancha, Balearic Islands, La Rioja, Navarra, Oviedo, Zaragoza and the Basque Country, form the Group G9 of Universities. Wikipedia.
Moral F.J.,University of Extremadura
International Journal of Climatology | Year: 2010
The benefits of an integrated geographical information system (GIS) and a geostatistics approach to accurately model the spatial distribution pattern of precipitation are known. However, the determination of the most appropriate geostatistical algorithm for each case is usually neglected, i.e. it is important to select the best interpolation technique for each study area to obtain accurate results. In this work, the ordinary kriging (OK), simple kriging (SK) and universal kriging (universal kriging) methods are compared with three multivariate algorithms which take into account the altitude: collocated ordinary cokriging (OCK), simple kriging with varying local means (SKV) and regression-kriging (RK). The different techniques are applied to monthly and annual precipitation data measured at 136 meteorological stations in a region of southwestern Spain (Extremadura). After carrying out cross-validation, the smallest prediction errors are obtained for the three multivariate algorithms but, particularly, SKV and RK outperform collocated OCK, which needs a more demanding variogram analysis. These algorithms are easily implemented in a GIS, requiring the residual estimates and map algebra capability to generate the final maps. Results evidence the necessity of accounting for spatially dependent precipitation data and the collocated altitude, to accurately define monthly and annual precipitation maps. © 2009 Royal Meteorological Society.
Santos A.,University of Extremadura
Physical Review Letters | Year: 2012
The chemical potential of a hard-sphere fluid can be expressed in terms of the contact value of the radial distribution function of a solute particle with a diameter varying from zero to that of the solvent particles. Exploiting the explicit knowledge of such a contact value within the Percus-Yevick theory, and using standard thermodynamic relations, a hitherto unknown Percus-Yevick equation of state, p/ρk BT=-(9/η)ln (1-η)-(16-31η)/ 2(1-η) 2, is unveiled. This equation of state turns out to be better than the one obtained from the conventional virial route. Interpolations between the chemical-potential and compressibility routes are shown to be more accurate than the widely used Carnahan-Starling equation of state. The extension to polydisperse hard-sphere systems is also presented. © 2012 American Physical Society.
Cantillo D.,University of Extremadura
European Journal of Inorganic Chemistry | Year: 2011
Ruthenium-catalyzed amide hydrogenation was thoroughly explored by means of DFT calculations. All the plausible pathways, including those involving the amide or imine tautomer, were assessed. The classical C-O cleavage and the recently reported C-N cleavage were compared by employing a bipyridyl-based RuII pincer complex as catalyst in the calculations. The study reveals that C-O cleavage can be achieved directly over the amide substrate or its imine tautomer, since the computed pathways show analogous energy barriers. In addition, the mechanism for the novel C-N cleavage was elucidated by modeling all the reasonable intermediates and transition structures. The computed energy barrier is lower than that for C-O cleavage by more than 10 kcal mol -1, thus explaining the observed selectivity. The key role of the aromatization/dearomatization processes during the transformation is also disclosed. The hydrogenation of amides catalyzed by ruthenium complexes has been analyzed by DFT methods. Both C-N and C-O bond cleavages have been compared by means of the relative energies of the key transitionstructures. Aromatization/dearomatization processes on the pincer complex reported by Milstein favor the C-N cleavage and fully explain the experimental results. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Cravotto G.,University of Turin |
Cintas P.,University of Extremadura
Chemical Science | Year: 2012
Chemical reactions may experience numerous and varied effects under the influence of ultrasound. This soft radiation, often viewed as a lab trick, induces and improves both physical and chemical transformations by means of efficient agitation, dissolution, mass and heat transfers, and reagents sonolysis, which all arise from the cavitational collapse. An empirical rationale that distinguishes between true chemical effects and mechanical ones, especially in heterogeneous reactions, was introduced more than two decades ago and has been a useful guidance on reporting sonochemical mechanisms. Recent studies have witnessed a truly remarkable data set that boosts sonochemistry over the wall of applied science. This perspective highlights the importance of the so-called false sonochemistry-closely related to mechanochemistry-in modern synthesis, thus illustrating the advantages of using pressure waves in chemistry. Emphasis is put on green transformations, mild polymerization reactions and the selective cleavage of functionalized polymers, which may have an effective impact in process chemistry and represent a realistic option in industry. © 2012 The Royal Society of Chemistry.
Rosado J.A.,University of Extremadura
Cell Calcium | Year: 2011
Changes in cytosolic free Ca 2+ concentration play a pivotal role in the regulation of platelet functions, from secretion of autocrine and procoagulant factors to reversible or irreversible aggregation. It has long been recognized that platelet agonists release Ca 2+ accumulated into the dense tubular system, the analogue of the endoplasmic reticulum. However, current evidence indicates that Ca 2+ can also be stored and released from a number of acidic organelles, including lysosomes and lysosome-related organelles. Ca 2+ release from the dense tubular system is mediated through phospholipase C-dependent synthesis of inositol 1,4,5-trisphosphate, whereas Ca 2+ efflux from the acidic stores seems to be associated to the second messenger nicotinic acid adenine dinucleotide phosphate. The biochemical and biophysical properties of both Ca 2+ stores in platelets have been reported to show significant differences. Selective discharge of one or both stores depends on the platelet agonist and the concentration used, which further supports the complexity of the Ca 2+ signals that regulate platelet function. In this paper, we summarize the current knowledge on the role of acidic organelles in agonist-evoked Ca 2+ mobilization and highlight recent progress in understanding the functional aspects of the acidic Ca 2+ stores in Ca 2+ signalling and platelet physiology. © 2010 Elsevier Ltd.