University of Extremadura

About: University of Extremadura is a education organization based out in Badajoz, Spain. It is known for research contribution in the topics: Population & Hyperspectral imaging. The organization has 7856 authors who have published 18299 publications receiving 396126 citations. The organization is also known as: Universidad de Extremadura.

A Family of Symmetric Distributions on the Circle

Abstract: We propose a new family of symmetric unimodal distributions on the circle that contains the uniform, von Mises, cardioid, and wrapped Cauchy distributions, among others, as special cases. The basic form of the densities of this family is very simple, although its normalization constant involves an associated Legendre function. The family of distributions can also be derived by conditioning and projecting certain bivariate spherically and elliptically symmetric distributions on to the circle. Trigonometric moments are available, and a measure of variation is discussed. Aspects of maximum likelihood estimation are considered, and likelihood is used to fit the family of distributions to an example set of data. Finally, extension to a family of rotationally symmetric distributions on the sphere is briefly made.

Phosphorylation of STIM1 at ERK1/2 target sites modulates store-operated calcium entry.

Abstract: Store-operated calcium entry (SOCE) is an important Ca2+ entry pathway that regulates many cell functions. Upon store depletion, STIM1, a transmembrane protein located in the endoplasmic reticulum (ER), aggregates and relocates close to the plasma membrane (PM) where it activates store-operated calcium channels (SOCs). Although STIM1 was early defined as a phosphoprotein, the contribution of the phosphorylation has been elusive. In the present work, STIM1 was found to be a target of extracellular-signal-regulated kinases 1 and 2 (ERK1/2) in vitro, and we have defined the ERK1/2-phosphorylated sites on the STIM1 sequence. Using HEK293 cells stably transfected for the expression of tagged STIM1, we found that alanine substitution mutants of ERK1/2 target sites reduced SOCE significantly, suggesting that phosphorylation of these residues are required to fully accomplish SOCE. Indeed, the ERK1/2 inhibitors PD184352 and PD0325901 decreased SOCE in transfected cells. Conversely, 12-O-tetradecanoylphorbol-13-acetate, which activates ERK1/2, enhanced SOCE in cells expressing wild-type tagged STIM1, but did not potentiate Ca2+ influx in cells expressing serine to alanine mutations in ERK1/2 target sites of STIM1. Alanine substitution mutations decreased Ca2+ influx without disturbing the aggregation of STIM1 upon store depletion and without affecting the relocalization in ER-PM punctae. However, our results suggest that STIM1 phosphorylation at ERK1/2 target sites can modulate SOCE by altering STIM1 binding to SOCs, because a significant decrease in FRET efficiency was observed between alanine substitution mutants of STIM1-GFP and ORAI1-CFP.

Potential use of electronic noses, electronic tongues and biosensors as multisensor systems for spoilage examination in foods

Abstract: • The Romanian National Authority for Scientific Research and Innovation, CNCS – UEFISCDI. Project number PN II-RU-TE-2014-4-1093

Multivariate Kernel Smoothing and Its Applications

Abstract: Preface List of Figures List of Tables List of Algorithms Introduction Exploratory data analysis with density estimation Exploratory data analysis with density derivatives estimation Clustering/Unsupervised learning Classification/Supervised learning Suggestions on how to read this monograph Density estimation Histogram density estimation Kernel density estimation Probability contours as multivariate quantiles Contour colour scales Gains from unconstrained bandwidth matrices Advice for practical bandwidth selection Squared error analysis Asymptotic squared error formulas Optimal bandwidths Convergence of density estimators Further mathematical analysis of density estimators Asymptotic expansion of the MISE Asymptotically optimal bandwidth Vector versus vector half parametrisations Bandwidth selectors for density estimation Normal scale bandwidths Maximal smoothing bandwidths Normal mixture bandwidths Unbiased cross validation bandwidths Biased cross validation bandwidths Plug in bandwidths Smoothed cross validation bandwidths Empirical comparison of bandwidth selectors Theoretical comparison of bandwidth selectors Further mathematical analysis of bandwidth selectors Relative convergence rates of bandwidth selectors Optimal pilot bandwidth selectors Convergence rates with data-based bandwidths Modified density estimation Variable bandwidth density estimators Balloon density estimators Sample point density estimators Bandwidth selectors for variable kernel estimation Transformation density estimators Boundary kernel density estimators Beta boundary kernels Linear boundary kernels Kernel choice Higher order kernels Further mathematical analysis of modified density estimators Asymptotic error for sample point variable bandwidth estimators Asymptotic error for linear boundary estimators Density derivative estimation Kernel density derivative estimators Density gradient estimators Density Hessian estimators General density derivative estimators Gains from unconstrained bandwidth matrices Advice for practical bandwidth selection Empirical comparison of bandwidths of different derivative orders Squared error analysis Bandwidth selection for density derivative estimators Normal scale bandwidths Normal mixture bandwidths Unbiased cross validation bandwidths Plug in bandwidths Smoothed cross validation bandwidths Convergence rates of bandwidth selectors Case study: the normal density Exact MISE Curvature matrix Asymptotic MISE Normal scale bandwidth Asymptotic MSE for curvature estimation Further mathematical analysis Taylor expansions for vector-valued functions Relationship between multivariate normal moments Applications related to density and density derivative estimation Level set estimation Modal region and bump estimation Density support estimation Density-based clustering Stable/unstable manifolds Mean shift clustering Choice of the normalising matrix in the mean shift Density ridge estimation Feature significance Supplementary topics in data analysis Density difference estimation and significance testing Classification Density estimation for data measured with error Classical density deconvolution estimation Weighted density deconvolution estimation Manifold estimation Nearest neighbour estimation Further mathematical analysis Squared error analysis for deconvolution kernel density estimators Optimal selection of the number of nearest neighbours Computational algorithms R implementation Approximate binned estimation Approximate density estimation Approximate density derivative and functional estimation Recursive normal density derivatives Recursive normal functionals Numerical optimisation over matrix spaces

Activated carbon adsorption of some phenolic compounds present in agroindustrial wastewater

Abstract: Single solute and simultaneous experimental adsorption isotherms of three phenolic compounds: gallic acid, p-hydroxybenzoic acid and syringic acid, have been investigated at 20, 30 and 40°C, using a bituminous coal based activated carbon. Regardless of temperature, the capacity of the activated carbon used to adsorb these compounds presented the following order: syringic acid > p-hydroxybenzoic acid > gallic acid. The increase of temperature slightly favored the adsorption capacity of the phenolic compounds. In binary and ternary component adsorption, experimental data suggest that interactions between adsorbates improve the adsorption capacity of some of the phenolic acid compounds. On the contrary, at high organic concentrations, adsorbed gallic acid was partially removed from the activated carbon surface because of the presence of the other components.