E-pSylon: una herramienta para la teleenseñanza síncrona

Muchas de las herramientas de teleenseñanza actuales corresponden al modelo asíncrono, donde instructor y alumnos interactúan desde espacios y tiempos diferentes. El modelo de teleenseñanza síncrona permite incorporar estrategias probadas con éxito en la enseñanza presencial, donde el apoyo visual del instructor a las explicaciones facilita la comprensión por parte de los alumnos. Se consigue así una enseñanza guiada y una realimentación inmediata de los alumnos. En este trabajo se propone una herramienta de teleenseñanza síncrona de sencillo manejo que permite el desarrollo de clases virtuales donde instructor y alumnos interactúan en tiempo real. También se presenta la experiencia con el uso de la herramienta en asignaturas relacionadas con la Ingeniería Informática y algunas conclusiones al respecto.Peer Reviewe

Current sensorless power factor correction based on digital current rebuilding

A new digital control technique for power factor correction is presented. The main novelty of the method is that there is no current sensor. Instead, the input current is digitally rebuilt, using the estimated input current for the current loop. Apart from that, the ADCs used for the acquisition of the input and output voltages have been designed ad-hoc. Taking advantage of the slow dynamic behavior of these voltages, almost completely digital ADCs have been designed, leaving only a comparator and an RC filter in the analog part. The final objective is obtaining a low cost digital controller which can be easily integrated in an ASIC along with the controller of paralleled and subsequent power section

Implantación, certificación e integración de sistemas de gestión en la minería española

La competitividad de los productos depende de dos elementos clave: su precio y su calidad. Hasta hace relativamente poco tiempo, el precio era considerado la variable de mayor peso, y en ocasiones la única a tener en cuenta en la decisión de compra. Por ello, la principal preocupación de las empresas estribaba en producir grandes cantidades de producto a bajo coste, sin casi dar importancia a la calidad. Sin embargo, el escenario en el que las organizaciones operan ha cambiado drásticamente. Por ello, en un entorno económico marcado por la globalización y la integración económica de los mercados, la calidad se presenta como una condición sine qua non no sólo para competir sino para la propia supervivencia empresarial. En otras palabras, la calidad ha pasado de ser una opción por la que apostaban sólo las empresas más dinámicas, a convertirse en una necesidad para cualquier organización que pretenda ser competitiva. Sin embargo, esta cualidad, la calidad, ha de estar presente no sólo en el producto y/o servicio ofertado, sino en todas y cada una de las operaciones que posibilitan su elaboración y/o prestación, y por tanto en la propia gestión empresarial. La implantación de sistemas de gestión de calidad, medio ambiente y seguridad y salud laboral ha pasado de ser una opción a convertirse en una prioridad para muchas organizaciones. Buena prueba de ello es el incesante incremento del número de certificaciones de dichos sistemas en todos los sectores de actividad. De entre ellos, nos centramos en la situación del sector de la minería e industrias extractivas por sus peculiares características: contaminantes y asociadas a elevadas tasa de siniestralidad. Al objeto de poder determinar hasta qué punto la implantación de los estándares de gestión ISO 14001 y OHSAS 18001, realmente tiene un carácter voluntario o si, por el contrario, se halla condicionada por la rigurosa legislación que, en materia medioambiental y de prevención de riesgos laborales, regula el desarrollo de la actividad minera en nuestro país, se realizó un estudio empírico entre las empresas mineras españolas que cuentan con uno o varios sistemas de gestión certificados. Asimismo, y dada la compatibilidad entre las normas ISO 9001, 14001 y OHSAS 18001, se analiza la situación de la integración de sistemas en el sector minero español.Product competitiveness depends on two key elements: price and quality. Not so long ago, the price was considered the only variable to bear in mind when making decisions about purchase. Because of this the principal worry of companies was to produce products in large quantities at low cost, without giving too much importance to quality. Nevertheless, the scene in which the companies operate has changed drastically. That is the reason why in a business environment marked by globalization and the economic integration of the markets, the quality appears as a condition sine qua non not only to compete but for company survival. In other words, the quality has passed from being an option that only the most dynamic companies were betting on, to a necessity for any organization that tries to be competitive. Nevertheless, the quality has to be present not only in the product and/or service offered, but also in each and every part of the process of production and therefore in the every management of the business. The implementation of quality, environment and occupational health and safety management systems has become a priority for many organizations. The increasing number of companies in all economic sectors seeking to attain certification of these management systems is clear evidence of this phenomenon. We analyse the situation of quarrying and mineral extraction industries because they belong to a sector with particular characteristics, such as high levels of pollution and accident rates. In order to be able to determine to what extent the implementation of the ISO 14001 and OHSAS 18001 standards really has a voluntary character, or, on the contrary, it is a result of the rigorous legislation that regulates the development of mining activities in our country, an empirical study was conducted among the Spanish mining companies that possess one o more certified management systems. Likewise, and given the existing compatibility among the ISO 9001, ISO 14001 and OHSAS 18001 standards, we analyze the integration of management systems in the Spanish mining sector

Characterizing global fire regimes from satellite-derived products

We identified four global fire regimes based on a k-means algorithm using five variables covering the spatial, temporal and magnitude dimensions of fires, derived from 19-year long satellite burned area and active fire products. Additionally, we assessed the relation of fire regimes to forest fuels distribution. The most extensive fire regime (35% of cells having fire activity) was characterized by a long fire season, medium size fire events, small burned area, high intensity and medium variability. The next most extensive fire regime (25.6%) presented a long fire season, large fire events and the highest mean burned area, yet it showed the lowest intensity and the least variability. The third group (22.07%) presented a short fire season, the lowest burned area, with medium-low intensity, the smallest fire patches and large variability. The fourth group (17.3%) showed the largest burned area with large fire patches of moderate intensity and low variability. Fire regimes and fuel types showed a statistically significant relation (CC = 0.58 and CC? = 0.67, p < 0.001), with most fuel types sustaining all fire regimes, although a clear prevalence was observed in some fuel types. Further efforts should be directed towards the standardization of the variables in order to facilitate comparison, analysis and monitoring of fire regimes and evaluate whether fire regimes are effectively changing and the possible drivers.Agencia Estatal de Investigació

Mixed Production of Filamentous Fungal Spores for Preventing Soil-Transmitted Helminth Zoonoses: A Preliminary Analysis

Helminth zoonoses are parasitic infections shared by humans and animals, being the soil-transmitted helminths (STHs) mainly caused by roundworms (ascarids) and hookworms. This study was aimed to assess the individual and/or mixed production of two helminth-antagonistic fungi, one ovicide (Mucor circinelloides) and other predator (Duddingtonia flagrans). Fungi were grown both in Petri plates and in a submerged culture (composed by water, NaCl, Na2HPO4 · 12 H2O, and wheat (Triticum aestivum)). A Fasciola hepatica recombinant protein (FhrAPS) was incorporated to the cultures to improve fungal production. All the cultured plates showed fungal growth, without difference in the development of the fungi when grown alone or mixed. High counts of Mucor spores were produced in liquid media cultures, and no significant differences were achieved regarding single or mixed cultures, or the incorporation of the FhrAPS. A significantly higher production of Duddingtonia spores after the incorporation of the FhrAPS was observed. When analyzing the parasiticide efficacy of the fungal mixture, viability of T. canis eggs reduced to 51%, and the numbers of third stage cyathostomin larvae reduced to 4%. It is concluded, the capability of a fungal mixture containing an ovicide (Mucor) and a predator species (Duddingtonia) for growing together in a submerged medium containing the FhrAPS offers a very interesting tool for preventing STHs.This work was partly supported by the Research Projects 10MDS261023PR (Xunta de Galicia, Spain) and AGL2012-34355 (Ministerio de Economía y Competitividad, Spain; FEDER)S

Assessing the Potential of Algae Extracts for Extending the Shelf Life of Rainbow Trout (Oncorhynchus mykiss) Fillets

This study evaluates the potential of different algae extracts (Crassiphycus corneus, Cc; Ulva ohnoi, Uo; Arthrospira platensis, Ap; Haematococcus pluvialis, Hp) as additives for the preservation of rainbow trout fillets. The extracts were prepared with different water to ethanol ratios from the four algae species. The highest ferric reducing antioxidant power (FRAP) was observed in Uo extracted in 80% ethanol. Ap aqueous extract also had considerable FRAP activity, in agreement with a high total phenolic content. Radical scavenging activity (DPPH) was higher in Cc 80% ethanol extract, in agreement with a high total carotenoid content. In fact, when the algae aqueous extracts were assayed on the fish fillets, their antioxidant activity exceeded that of ascorbic acid (ASC). All algae extracts delayed microbial growth and lipid oxidation processes in trout fillets throughout the cold storage period compared to controls, and also improved textural parameters, these effects being more evident for Ap and Hp. With respect to the color parameters, the Hp extract prevented the a* values (redness) from decreasing throughout cold storage, a key point when it comes to colored species, not least salmonids. On the other hand, the Ap extract was not as effective as the rest of treatments in avoiding a* and b* decrease throughout the storage period, and thereby the color parameters were impaired. The results obtained, together with the natural origin and the viability for large-scale cultivation, make algae extracts interesting fish preservative agents for the food industry

Estudio comparativo de perfil lipídico y presión arterial en caninos delgados y con sobrepeso

The aim of the present study was to compare levels of cholesterol, triglycerides, and blood pressure in canines. A total of 60 dogs were used (30 were lean and 30 were overweight). The animals were patients from the Clinic of Small Animals of the Faculty of Veterinary Medicine of the National University of San Marcos and were free of heart diseases. Blood samples were collected and processed by photocolorimetry in a chemical analyzer and the blood pressure measurement was done with a digital blood pressure monitor. The results showed hypertriglyceridemia in 16.7% of the overweight group, while 46.7% of the lean group and 90% of the overweight group showed hypercholesterolemia. In addition, 20 and 50% of the lean and overweight group respectively had high blood pressure values. Triglyceride and cholesterol levels were significantly higher in the overweight group (p&lt;0.05), whereas there were no differences in systolic blood pressure values. There was an association between lean and overweight dogs with triglycerides and cholesterol.El objetivo del presente estudio fue comparar los niveles de colesterol, triglicéridos y presión arterial en caninos. Se trabajó con 60 caninos, de los cuales 30 eran delgados y 30 tenían sobrepeso. Los animales eran pacientes de la Clínica de Animales Menores de la Facultad de Medicina Veterinaria de la Universidad Nacional Mayor de San Marcos y eran libres de enfermedades cardiacas. Las muestras de sangre colectadas fueron procesadas mediante fotocolorimetría en un analizador químico y la medida de la presión arterial se hizo con un tensiómetro digital. Los resultados demostraron una hipertrigliceridemia en el 16.7% del grupo sobrepeso, mientras que el 46.7% del grupo delgado y el 90% del grupo sobrepeso mostraron hipercolesterolemia. El 20 y 50% de los canes del grupo delgado y sobrepeso, respectivamente, registraron valores de hipertensión arterial. Los niveles de triglicéridos y colesterol fueron significativamente superiores en el grupo sobrepeso (p&lt;0.05), mientras que no hubo diferencias en los valores de la presión arterial sistólica. Se encontró una asociación entre los caninos delgados y con sobrepeso con las variables triglicéridos y colesterol

Low-temperature spin excitations in frustrated ZnCr2O4 probed by high-field thermal conductivity

The magnetoelastic excitations of spin frustrated ZnCr2O4 are studied by the magnetic field dependence of the thermal conductivity k down to 50 mK. Above the first-order magnetostructural transition at TN,S≈ 12.5 K, spin fluctuations are strongly coupled to acoustic phonons, leading to a glasslike dependence of k(T), up to Θ CW. In the symmetry broken phase below TN,S, k shows a dominant magnetic contribution even at the lowest temperatures probed in this work. Application of a magnetic field above 2.5 T destabilizes the spin-bond structure, leading to a sudden increase and a nonconventional temperature dependence of the thermal conductivity. The possibility of the coexistence of gapped and gapless excitations in this magnetic phase is discussedThis work was partially supported by MAT2010-16157 (Ministerio de Economía y Competitividad, Spain) and by the DFG via TRR 80 (Augsburg-Munich). Z.Y.Z. and X.F.S. acknowledge support from the National Natural Science Foundation of China, the National Basic Research Program of China (Grant Nos. 2009CB929502 and 2011CBA00111), and the Fundamental Research Funds for the Central Universities (Program No. WK2340000035). V.Z. acknowledges Los Alamos National Lab Directed Research Project 2010000043DRS