Valence change of praseodymium in Pr0.5Ca0.5CoO3 investigated by x-ray absorption spectroscopy

X-ray absorption spectroscopy measurements in Pr0.5Ca0.5CoO3 were performed at the Pr M4,5, Pr L3, and Ca L2,3 absorption edges as a function of temperature below 300 K. Ca spectra show no changes down to 10 K while a noticeable thermally dependent evolution takes place at the Pr edges across the metal-insulator transition. Spectral changes are analyzed by different methods, including multiple scattering simulations, which provide quantitative details on an electron loss at Pr 4f orbitals. We conclude that in the insulating phase a fraction [15(+5)%] of Pr3+ undergoes a further oxidation to adopt a hybridized configuration composed of an admixture of atomic-like 4f1 states (Pr4+) and f- symmetry states on the O 2p valence band (Pr3+L states) indicative of a strong 4f- 2p interaction.Comment: 19 pages (.doc), 4 figures, Phys. Rev. B, in pres

Estado del Arte en Cambio Climático, Agricultura y Seguridad Alimentaria en Costa Rica

El cambio climático ha provocado numerosos efectos en el medio rural de Costa Rica; es por esto que el Ministerio de Agricultura y Ganadería de Costa Rica (MAG) en colaboración con el Programa de Investigación de CGIAR en Cambio Climático, Agricultura y Seguridad Alimentaria (CCAFS) en América Latina y con apoyo del Consejo Agropecuario Centroamericano (CAC) presentan el “Estado del Arte en Cambio Climático, Agricultura y Seguridad Alimentaria en Costa Rica”, que incluye el marco gubernamental y actores involucrados en torno a esta temática. El documento evidencia, los múltiples esfuerzos que en acciones de mitigación frente al calentamiento global viene realizando Costa Rica, convirtiéndolo en país líder en la región de América Central. Buena parte de los avances han sido obtenidos en el sector agropecuario

Clinical guideline SEOM: cancer of unknown primary site

Cancer of unknown primary site is a histologically confirmed cancer which is manifested in advanced stage, with no identifiable primary site after the use of standard diagnostic procedures. Patients are initially placed into one of categories based upon the examination of the initial biopsy: adenocarcinoma, squamous cell carcinoma, neuroendocrine carcinoma and poorly differentiated carcinoma. Appropriate patient management requires an understanding of several clinicopathologic features that help to identify several subsets of patients with more responsive tumors

Predicting the distribution of canine leishmaniasis in western Europe based on environmental variables.

The domestic dog is the reservoir host of Leishmania infantum, the causative agent of zoonotic visceral leishmaniasis endemic in Mediterranean Europe. Targeted control requires predictive risk maps of canine leishmaniasis (CanL), which are now explored. We databased 2187 published and unpublished surveys of CanL in southern Europe. A total of 947 western surveys met inclusion criteria for analysis, including serological identification of infection (504, 369 dogs tested 1971-2006). Seroprevalence was 23 2% overall (median 10%). Logistic regression models within a GIS framework identified the main environmental predictors of CanL seroprevalence in Portugal, Spain, France and Italy, or in France alone. A 10-fold cross-validation approach determined model capacity to predict point-values of seroprevalence and the correct seroprevalence class (20%). Both the four-country and France-only models performed reasonably well for predicting correctly the 20% seroprevalence classes (AUC >0 70). However, the France-only model performed much better for France than the four-country model. The four-country model adequately predicted regions of CanL emergence in northern Italy (<5% seroprevalence). Both models poorly predicted intermediate point seroprevalences (5-20%) within regional foci, because surveys were biased towards known rural foci and Mediterranean bioclimates. Our recommendations for standardizing surveys would permit higher-resolution risk mapping

A Review Characterizing 25 Ecosystem Challenges to Be Addressed by an Ecosystem Approach to Fisheries Management in Europe

The impacts of fisheries on ocean resources are no longer considered in isolation but should account for broader ecosystem effects. However, ongoing ecosystem-wide changes added to the inherent dynamics of marine ecosystems, create challenges for fisheries and fisheries management by affecting our ability to ensure future fishing opportunities and sustainable use of the seas. By reviewing a corpus of fisheries science literature, we contribute to informing managers and policymakers with considerations of the various threats to fisheries and the marine ecosystems that support them. We identify and describe 25 ecosystem challenges and 7 prominent families of management options to address them. We capture the challenges acting within three broad categories: (i) fishing impacts on the marine environments and future fishing opportunities, (ii) effects of environmental conditions on fish and fishing opportunities, and (iii) effects of context in terms of socioeconomics, fisheries management, and institutional set-up on fisheries. Our review shows that, while most EU fisheries are facing a similar array of challenges, some of them are specific to regions or individual fisheries. This is reflected in selected regional cases taking different perspectives to exemplify the challenges along with fishery-specific cases. These cases include the dramatic situation of the Baltic Sea cod, facing an array of cumulative pressures, the multiple and moving ecosystem interactions that rely on the North Sea forage fish facing climate change, the interaction of fishing and fish stocks in a fluctuating mixed fishery in the Celtic Sea, the bycatch of marine mammals and seabirds and habitat degradation in the Bay of Biscay, and finally the under capacity and lack of fundamental knowledge on some features of the EU Outermost Regions. In addition to these ecoregion specific findings, we discuss the outcomes of our review across the whole of European waters and we conclude by recognizing that there are knowledge gaps regarding the direction of causality, nonlinear responses, and confounding effects. All of the challenges we identify and characterize may guide further data collection and research coordination to improve our fundamental understanding of the system and to monitor real changes within it, both of which are required to inform an Ecosystem Approach to Fisheries Management (EAFM). An European EAFM could build upon an array of management measures currently tailored for fisheries management only, including promoting funding interdisciplinary research and ecosystem monitoring. Such integrative management should reduce uncertainties in environmental, social and economic trends, and lower the risk for disruptive events or ecosystem effects with far-reaching consequences, including a shift toward less productive marine ecosystems.En prens

Secado de café pergamino por lecho fluidizado con asistencia de microondas

Tradicionalmente el secado del café pergamino húmedo en Colombia, se realiza por secado solar y aire caliente. El tiempo, temperatura, color del grano y principalmente el contenido de humedad final entre 10-12% b.h. se utilizan para establecer el punto final del proceso. Se estudiaron los cambios en las características físicas y parámetros hidrodinámicos del café pergamino húmedo en lecho fluidizado y secado por microondas, utilizando un diseño factorial 32 (velocidad del aire: 2, 4 y 6 m/s con 50, 80 y 100% de potencia del microondas) hasta alcanzar el nivel de humedad final. La fluidización se obtiene circulando aire al sector de secado a través de una placa (33 cm x 32 cm) con un tamaño de orificios de 5 mm con una distancia entre ellos de 7 mm (2116 orificios). En el sector de secado, el producto en estado fluidizado, fue irradiado mediante un magnetrón (1000 W). La mejor condición es: velocidad del aire de 4 m/s con 100% de potencia del microondas en 72 minutos, con una reducción del contenido de humedad hasta 11,3% b.h. La difusividad efectiva varió entre 9,19x10-12 y 1,33x10-11 m2/s. La energía de activación y factor pre-exponencial se determinó como 2,9 W/g y 2x10-10 m2/s.Traditionally drying of wet parchment coffee in Colombia, it is by solar drying and hot air. Time, temperature, grain color and mainly the final moisture content between 10-12% w.b. are used to set the end point of the process. The changes were studied in the physical characteristics and hydrodynamic parameters of wet parchment coffee in fluidized bed and microwave drying by using a factorial design 32 (air speed: 2, 4 and 6 m/s with 50, 80 and 100% microwave power) until reach the final moisture level. The fluidization is obtained by circulating air to the drying sector through a plate (33 cm x 32 cm) with a size of holes 5 mm with a distance between them of 7 mm (2116 holes). In the drying sector, the product in the fluidized state, was irradiated by a magnetron (1000 W). The best condition is air velocity of 4 m/s with 100% microwave power for 72 minutes, with moisture content 11.3% w.b. The effective diffusivity varied between 9.19x10-12 and 1.33x10-11 m2/s. The activation energy and pre-exponential factor for moisture diffusion was determined as 2.9 W/g y 2x10-10 m2/s.Centro de Investigación y Desarrollo en Criotecnología de Alimento

Modelado matemático del secado con aire y microondas de café Pergamino

El secado de alimentos es una técnica milenaria para la conservación de alimentos, sin embargo para comprender con mayor profundidad los mecanismos de transferencia de energía y materia que ocurren durante el proceso es necesario recurrir al modelado computacional. Los modelos matemáticos son herramientas avanzadas para estudiar el comportamiento y describir los fenómenos que ocurren en el procesamiento de alimentos. El objetivo del presente trabajo fue estudiar experimental y teóricamente la transferencia de energía y materia durante el secado con aire y microondas de café. En el modelado computacional fueron consideradas condiciones convectivas que tienen en cuenta el efecto del flujo de aire en la geometría 3D del grano de café pergamino. Asímismo, para la transferencia de energía se utilizó la ley de Fourier y para la transferencia de materia la ley de Fick, ambas en estado no estacionario. Con el propósito de incorporar el efecto de las microondas sobre los granos de café, se incorporó una fuente de calor constante. Los balances de energía y materia fueron resueltos a través del método de elementos finitos utilizando el software comercial COMSOL Multiphysics, aplicando el solucionador multifrontal directo (MUMPS) dependiente del tiempo. La validación fue realizada por comparación con experimentos de secado de café pergamino sometido a un flujo de aire de 2 m/s y una potencia de microondas de 1×106 W/m3 , obteniendo buena concordancia entre los datos experimentales y las simulaciones.Centro de Investigación y Desarrollo en Criotecnología de Alimento