Effect of calcium sulfate source on the hydration of calcium sulfoaluminate eco-cement

The availability of cements, including eco-cements, with tailored mechanical properties is very important for special applications in the building industry. Here we report a full study of the hydration of calcium sulfoaluminate eco-cements with different sulfate sources (gypsum, bassanite and anhydrite) and two water/cement ratios (0.50 and 0.65). These parameters have been chosen because they are known to strongly modify the mechanical properties of the resulting mortars and concretes. The applied multitechnique characterization includes: phase assemblage by Rietveld method, evolved heat, conductivity, rheology, compressive strength and expansion/retraction measurements. The dissolution rate of the sulfate sources is key to control the hydration reactions. Bassanite dissolves very fast and hence the initial setting time of the pastes and mortars is too short (20 min) to produce homogeneous samples. Anhydrite dissolves slowly so, at 1 hydration-day, the amount of ettringite formed (20 wt%) is lower than that in gypsum pastes (26 wt%) (w/c = 0.50), producing mortars with lower compressive strengths. After 3 hydration-days, anhydrite pastes showed slightly larger ettringite contents and hence, mortars with slightly higher compressive strengths. Ettringite content is the chief parameter to explain the strength development in these eco-cements.Universidad de Málaga. Campus de Excelencia Interncaional Andalucía Tech

Current methods of soccer match analysis

Ha sido realizada una revisión de 86 artículos, con el objetivo de analizar a través de los estudios más recientes los beneficios y limitaciones de los nuevos sistemas para el análisis del futbolista durante el partido, debido a que las mayores exigencias en el rendimiento del fútbol moderno está obligando a replantearse cuáles son sus demandas físicas, así como los modelos de planificación y los métodos de entrenamiento tradicionales. Los resultados muestran que el vídeo análisis asistido por ordenador para la codificación de los patrones de movimiento y la tecnología GPS se presentan como herramientas de gran utilidad para conocer mejor la carga física del jugador, mientras que el diseño observacional facilita la evaluación del comportamiento técnico-táctico del futbolista y el equipo. Como conclusión podemos decir que hemos observado sin embargo una metodología diferente entre las opciones comerciales disponibles y una tecnología ubicada todavía en una etapa inicial de desarrolloA review of 86 references has been made, in order to analyze through the most recent studies the benefits and limitations of the new systems for the analysis of soccer player during the match, due to the fact that the greater performance requirements of modern soccer is forcing to review his physical demands, as well as planning models and traditional training methods. The results show that the computer-aided video analysis for coding movement patterns and the GPS technology are presented as very useful tools for a better understanding of the players physical load, whereas the observational design facilitates assessment of the technical-tactical behavior of the soccer player and the team. In conclusion we can say that we have however observed a different methodology among the available commercial options and a technology still placed at an initial stage of development

CMB polarization as a probe of the anomalous nature of the Cold Spot

One of the most interesting explanations for the non-Gaussian Cold Spot (CS) detected in the WMAP data by Vielva et al. 2004, is that it arises from the interaction of the CMB radiation with a cosmic texture (Cruz et al. 2007b). In this case, a lack of polarization is expected in the region of the spot, as compared to the typical values associated to large fluctuations of a GIRF. In addition, other physical processes related to a non-linear evolution of the gravitational field could lead to a similar scenario. However, some of these alternative scenarios (e.g., a large void in the large scale structure) have been shown to be very unlikely. In this work we characterise the polarization properties of the Cold Spot under both hypotheses: a large Gaussian spot and an anomalous feature generated, for instance, by a cosmic texture. We propose a methodology to distinguish between them, and we discuss its discrimination power as a function of the instrumental noise level. In particular, we address the cases of current experiments, like WMAP and Planck, and others in development as QUIJOTE. We find that for an ideal experiment the Gaussian hypothesis could be rejected at a significance level better than 0.8%. While WMAP is far from providing useful information in this respect, we find that Planck will be able to reach a significance of around 7%; in addition, we show that the ground-based experiment QUIJOTE could provide a significance of around 1%. If these results are combined with the significance level found for the CS in temperature, the capability of QUIJOTE and Planck to reject the alternative hypothesis becomes 0.025% and 0.124%, respectively.Comment: 7 pages, 3 figures, accepted in MNRAS. Minor changes made to match the final versio

Low genetic diversity and recent demographic expansion in the red starfish Echinaster sepositus (Retzius 1816)

16 páginas, 5 tablas, 7 figuras.Understanding the phylogeography and genetic structure of populations and the processes responsible of patterns therein is crucial for evaluating the vulnerability of marine species and developing management strategies. In this study, we explore how past climatic events and ongoing oceanographic and demographic processes have shaped the genetic structure and diversity of the Atlanto- Mediterranean red starfish Echinaster sepositus. The species is relatively abundant in some areas of the Mediterranean Sea, but some populations have dramatically decreased over recent years due to direct extraction for ornamental aquariums and souvenir industries. Analyses across most of the distribution range of the species based on the mitochondrial cytochrome c oxidase subunit I gene and eight microsatellite loci revealed very low intraspecific genetic diversity. The species showed a weak genetic structure within marine basins despite the a priori low dispersal potential of its lecithotrophic larva. Our results also revealed a very recent demographic expansion across the distribution range of the species. The genetic data presented here indicate that the species might be highly vulnerable, due to its low intraspecific genetic diversity.This study was supported by a FPI-MICINN PhD fellowship (BES-2011-044154) to AGC, a ‘Juan de la Cierva’ contract from the Spanish Government to RPP, and the Spanish government research projects BENTHOMICS (CTM2010-22218-C02-) and CHALLENGEN (CTM2103-48163). This paper is a contribution of the Consolidated Research Group 2009SRG665 supported by the Generalitat de Catalunya.Peer reviewe

The radial BAO scale and Cosmic Shear, a new observable for Inhomogeneous Cosmologies

As an alternative explanation of the dimming of distant supernovae it has recently been advocated that we live in a special place in the Universe near the centre of a large spherical void described by a Lemaitre-Tolman-Bondi (LTB) metric. In this scenario, the Universe is no longer homogeneous and isotropic, and the apparent late time acceleration is actually a consequence of spatial gradients. We propose in this paper a new observable, the normalized cosmic shear, written in terms of directly observable quantities, and calculable in arbitrary inhomogeneous cosmologies. This will allow future surveys to determine whether we live in a homogeneous universe or not. In this paper we also update our previous observational constraints from geometrical measures of the background cosmology. We include the Union Supernovae data set of 307 Type Ia supernovae, the CMB acoustic scale and the first measurement of the radial baryon acoustic oscillation scale. Even though the new data sets are significantly more constraining, LTB models -- albeit with slightly larger voids -- are still in excellent agreement with observations, at chi^2/d.o.f. = 307.7/(310-4)=1.005. Together with the paper we also publish the updated easyLTB code used for calculating the models and for comparing them to the observations.Comment: 18 pages, 8 figures, the code can be downloaded at http://www.phys.au.dk/~haugboel/software.shtm

Obtención por vía SHS-AE de compuesto cerámico αSiC-αAl2O3-CaAl4O7

El presente trabajo muestra los resultados experimentales de la obtención del compuesto cerámico SiC-Al2O3-CaAl 4O7 mediante el proceso SHS-AE (síntesis auto-sostenida de alta temperatura combinada con arco eléctrico) a partir del sistema vidrio sódico-cálcico-Al-C. Se utilizó horno de arco eléctrico con atmósfera de argón para la reducción del contenido de sílice presente en el vidrio con aluminio.La combinación de la energía de la reacción de formación del Al2O3 con la del arco eléctrico provee suficiente energía térmica para superar las barreras cinéticas asociadas con la reacción de formación de los componentes cerámicos.A partir de las relaciones estequiométricas de las materias primas, (polvos que se compactan en forma de pastilla) se efectúa la síntesis alcanzando una temperatura superior a los 2500 K formándose el compuesto SiC-Al2O3-CaAl 4O7. Las muestras obtenidas se caracterizaron por DRX y MEB-EDX confirmando la obtención simultánea de αSiC-αAl2O3-CaAl4O7

Algoritmo mixto mínima entropía-máxima información para la selección de ítems en un test adaptativo informatizado

El objetivo del estudio que presentamos es comparar la eficacia como estrategia de selección de ítems de tres algoritmos diferentes: a) basado en máxima información; b) basado en mínima entropía; y c) mixto mínima entropía en los ítems iniciales y máxima información en el resto; bajo la hipótesis de que el algoritmo mixto, puede dotar al TAI de mayor eficacia. Las simulaciones de procesos TAI se realizaron sobre un banco de 28 ítems de respuesta graduada calibrado según el modelo de Samejima, tomando como respuesta al TAI la respuesta original de los sujetos que fueron utilizados para la calibración. Los resultados iniciales muestran cómo el criterio mixto es más eficaz que cualquiera de los otros dos tomados independientemente. Dicha eficacia se maximiza cuando el algoritmo de mínima entropía se restringe a la selección de los primeros ítems del TAI, ya que con las respuestas a estos primeros ítems la estimación de θ comienza a ser relevante y el algoritmo de máxima información se optimiza.Item selection algorithms in computerized adaptive testing. The aim of this paper is to compare the efficacy of three different item selection algorithms in computerized adaptive testing (CAT). These algorithms are based as follows: the first one is based on Item Information, the second one on Entropy, and the last algorithm is a mixture of the two previous ones. The CAT process was simulated using an emotional adjustment item bank. This item bank contains 28 graded items in six categories, calibrated using Samejima (1969) Graded Response Model. The initial results show that the mixed criterium algorithm performs better than the other ones

Development and Evaluation of \u3cem\u3ePennisetum Purpureum\u3c/em\u3e Mutants Through Irradiation With \u3csup\u3e60\u3c/sup\u3eCo

The development of plant mutants is a commonly used procedure nowadays. One way of obtaining mutant plants has been seed irradiation with gamma rays. As these studies are not common in tropical pasture species (Micke et al., 1993, Herrera, 2001), the objective of this study was the development and evaluation of Pennisetum purpureum mutants through irradiation with 60Co

Enzymatic hydrolysis of esters from 2-carboxy-6- methoxy-2,3-dihydrobenzofuran acid

In this work we describe the results of the enzymatic hydrolysis of esters from 2-carboxy-6-methoxy-2,3-dihydrobenzofuran acid using Candida antarctica lipase supported on acrylic resin, with enantiomeric excesses ranging between 80 to 99%