145 research outputs found

    Diseño de una estrategia didactica para propiciar el cambio conceptual sobre electrostatica en alumnos de secundaria

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    Muchos especialistas en didáctica de las ciencias se han cuestionado cuáles son las causas por las que los alumnos piensan que aprender ciencias es difícil y por qué enfrentan dicha dificultad. Algunos se han enfocado, en primer lugar, no al cómo se enseña ciencias, sino cómo aprenden los sujetos; encontrando que aprenden construyendo su propio conocimiento. Se presenta un proyecto donde se diseñó y probó una estrategia didáctica, para transformar las ideas previas de los alumnos de secundaria sobre electrostática, utilizando un enfoque del cambio conceptual que toma como punto de partida a la posición constructivista, y además nos muestra las dificultades de aprendizaje que tienen los alumnos acerca de este tema

    Collaborative hierarchy maintains cooperation in asymmetric games

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    The interplay of social structure and cooperative behavior is under much scrutiny lately as behavior in social contexts becomes increasingly relevant for everyday life. Earlier experimental work showed that the existence of a social hierarchy, earned through competition, was detrimental for the evolution of cooperative behaviors. Here, we study the case in which individuals are ranked in a hierarchical structure based on their performance in a collective effort by having them play a Public Goods Game. In the first treatment, participants are ranked according to group earnings while, in the second treatment, their rankings are based on individual earnings. Subsequently, participants play asymmetric Prisoner's Dilemma games where higher-ranked players gain more than lower ones. Our experiments show that there are no detrimental effects of the hierarchy formed based on group performance, yet when ranking is assigned individually we observe a decrease in cooperation. Our results show that different levels of cooperation arise from the fact that subjects are interpreting rankings as a reputation which carries information about which subjects were cooperators in the previous phase. Our results demonstrate that noting the manner in which a hierarchy is established is essential for understanding its effects on cooperation.A.A. gratefully acknowledges the financial support of the Swiss National Science Foundation under Grants No. P2LAP1-161864 and P300P1-171537. This work was also supported by the EU through FET-Proactive Project DOLFINS (contract no. 640772, A.S.) and FET-Open Project IBSEN (contract no. 662725, A.S.), and by the Ministerio de Econom a y Competitividad of Spain (grant no. FIS2015-64349-P, A.S.) (MINECO/FEDER, UE)

    Combination of X-ray crystallography, SAXS and DEER to obtain the structure of the FnIII-3,4 domains of integrin a6b4

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    Integrin alpha6beta4 is a major component of hemidesmosomes that mediate the stable anchorage of epithelial cells to the underlying basement membrane. Integrin alpha6beta4 has also been implicated in cell proliferation and migration and in carcinoma progression. The third and fourth fibronectin type III domains (FnIII-3,4) of integrin beta4 mediate binding to the hemidesmosomal proteins BPAG1e and BPAG2, and participate in signalling. Here, it is demonstrated that X-ray crystallography, small-angle X-ray scattering and double electron– electron resonance (DEER) complement each other to solve the structure of the FnIII-3,4 region. The crystal structures of the individual FnIII-3 and FnIII-4 domains were solved and the relative arrangement of the FnIII domains was elucidated by combining DEER with site-directed spin labelling. Multiple structures of the interdomain linker were modelled by Monte Carlo methods complying with DEER constraints, and the final structures were selected against experimental scattering data. FnIII-3,4 has a compact and cambered flat structure with an evolutionary conserved surface that is likely to correspond to a protein-interaction site. Finally, this hybrid method is of general application for the study of other macromolecules and complexes

    Known by the company we keep: `Triadic influence' as a proxy for compatibility in social relationships

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    Networks of social interactions are the substrate upon which civilizations are built. Often, we create new bonds with people that we like or feel that our relationships are damaged through the intervention of third parties. Despite their importance and the huge impact that these processes have in our lives, quantitative scientific understanding of them is still in its infancy, mainly due to the difficulty of collecting large datasets of social networks including individual attributes. In this work, we present a thorough study of real social networks of 13 schools, with more than 3,000 students and 60,000 declared positive and negative relations, including tests for personal traits of all the students. We introduce a metric -- the `triadic influence' -- that measures the influence of nearest-neighbors in the relationships of their contacts. We use neural networks to predict the relationships and to extract the probability that two students are friends or enemies depending on their personal attributes or the triadic influence. We alternatively use a high-dimensional embedding of the network structure to also predict the relationships. Remarkably, the triadic influence (a simple one-dimensional metric) achieves the highest accuracy at predicting the relationship between two students. We postulate that the probabilities extracted from the neural networks -- functions of the triadic influence and the personalities of the students -- control the evolution of real social networks, opening a new avenue for the quantitative study of these systems

    Systemic administration of a fibroblast growth factor receptor 1 agonist rescues the cognitive deficit in aged socially isolated rats.

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    Social isolation predominantly occurs in elderly people and it is strongly associated with cognitive decline. However, the mechanisms that produce isolation-related cognitive dysfunction during aging remain unclear. Here, we evaluated the cognitive, electrophysiological, and morphological effects of short- (4 weeks) and long-term (12 weeks) social isolation in aged male Wistar rats. Long-term but not short-term social isolation increased the plasma corticosterone levels and impaired spatial memory in the Morris water maze. Moreover, isolated animals displayed dampened hippocampal long-term potentiation in vivo, both in the dentate gyrus (DG) and CA1, as well as a specific reduction in the volume of the stratum oriens and spine density in CA1. Interestingly, social isolation induced a transient increase in hippocampal basic fibroblast growth factor (FGF2), whereas fibroblast growth factor receptor 1 (FGFR1) levels only increased after long-term isolation. Importantly, subchronic systemic administration of FGL, a synthetic peptide that activates FGFR1, rescued spatial memory in long-term isolated rats. These findings provide new insights into the neurobiological mechanisms underlying the detrimental effects on memory of chronic social isolation in the aged.pre-print507 K

    Primera cita de cocodrilos zifodontos en el Cenozoico de Asturias: Royo Gómez y los supuestos dientes de dinosaurio del Eoceno de Llamaquique

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    In 1928, José Royo Gómez mentioned the find of “two teeth similar to those of theropod dinosaurs from the Secondary” in the Eocene of Llamaquique (Oviedo Basin, Asturias). Royo Gómez was aware of the interest of the discovery, “because they would be the youngest remains found of these gigantic reptiles”. According to the hitherto unpublished documents preserved in the Archives of the Museo Nacional de Ciencias Naturales in Madrid, Royo Gómez photographed five teeth from Llamaquique in April 1932, which he regarded as belonging to theropods. The whereabouts of this material is currently unknown. However, the revision of the Llamaquique collection in the above mentioned museum has allowed to recover one labiolingually compressed and serrated tooth (ziphodont condition). We reject here that the tooth belongs to a theropod, and we assign it to a Mesoeucrocodylia indet. This is the first mention of the discovery of ziphodont crocodyliforms in the Paleogene of Asturias.En 1928, José Royo Gómez informó del hallazgo de “dos dientes idénticos a los de los Dinosaurios terópodos del Secundario” en el Eoceno de Llamaquique (Cuenca de Oviedo, Asturias). Royo Gómez era consciente del interés de este descubrimiento, “pues serían los restos más modernos que se conocerían de estos gigantescos reptiles”. Según la documentación conservada en el Archivo del Museo Nacional de Ciencias Naturales en Madrid, hasta ahora inédita, Royo Gómez fotografió en abril de 1932 cinco dientes de Llamaquique que él consideraba pertenecientes a terópodos. Este material se encuentra actualmente en paradero desconocido. No obstante, la revisión de la colección paleontológica de Llamaquique en el mencionado museo ha permitido recuperar un diente comprimido lateralmente y provisto de carenas denticuladas (condición zifodonta). Se descarta que el diente pertenezca a un terópodo, asignándose a un Mesoeucrocodylia indeterminado. Se trata de la primera mención del hallazgo de cocodrilos zifodontos en el Paleógeno de Asturias

    Effect of metal loading on the CO2 methanation: A comparison between alumina supported Ni and Ru catalysts

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    The hydrogenation of CO2 into CH4 from H2 produced by renewable energy is considered an interesting alternative in order to promote the development of such green energies. In the present work, the effect of Ni and Ru loadings on the catalytic performance of alumina-supported catalysts is studied for CO2 methanation reaction. All catalysts were prepared by wetness incipient impregnation, characterized by several techniques (N2-physisorption, CO2-TPD, XRD, H2-chemisorption, XPS and H2-TPR) and evaluated for CO2 methanation in a fixed bed reactor at GHSV=10,000 h−1 and W/FCO2 0 = 4.7 (g cat.) h mol−1. Characterization results showed that addition of increasing loadings of Ni and Ru lead to the formation of both CO2 adsorption and H2 dissociation active sites, which are necessary to carry out CO2 hydrogenation into methane. Easily reducible ruthenium was dispersed on γ-Al2O3 in form of large agglomerates, whereas Ni was better dispersed presenting a great interaction with the support. 12% Ni and 4% Ru resulted to be the optimal contents providing metal surfaces of 5.1 and 0.6m2 g−1, T50 values of 340 and 310 °C and activity being quite stable for 24 h-on-stream. In terms of turnover frequency (TOF), 4%Ru/Al2O3 catalyst was quite more efficient than 12%Ni/Al2O3, probably due to a greater ability of ruthenium to dissociate hydrogen. The apparent activation energies for alumina supported Ni and Ru were 129 and 84 kJ mol−1, respectively.The support from the Economy and Competitiveness Spanish Ministry (CTQ2015-67597-C2-1-R and CTQ2015-67597-C2-2-R MINECO-FEDER), the Basque Government (IT657-13 and IT1297-19) and the SGIker (Analytical Services) at the University of the Basque Country are acknowledged. One of the authors (AQ) also acknowledges University of the Basque Country by his PhD grant (PIF-15/351)

    NWCSAF GEO v2016 : new products, changes and improvements

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    Póster presentado en: 2016 EUMETSAT Meteorological Satellite Conference, 26-30 September 2016, Darmstadt, GermanyThe objective of the Nowcasting Satellite Application Facility (NWC SAF) is the generation of satellite derived products for their direct application to Nowcasting for targeted users. To achieve this goal, the NWC SAF team develops, maintains and distributes software packages that allows the users to generate, at their premises and for the user defined area, satellite derived products with a direct application to Nowcasting. The NWC SAF distributes two different software packages for GEO and LEO satellites. Current operational software package for GEO satellites is MSG v2013, distributed in 2013 and applicable to MSG data. Products generated with MSG v2013 include Cloud Products (Cloud Mask, Cloud Top Temperature and Height, Cloud Type, Cloud phase), Precipitation Products (Probability of Precipitation and Convective Rainfall Rate and Probability of Precipitation and Convective Rainfall Rate from Cloud Microphysics), High Resolution Winds (HRW), Water content and Instability Indices, Automatic Satellite Image Interpretation and detection and tracking of Rapidly Developing Convective Cells. A new software package, GEO v2016, has been distributed in November 2016. Main changes and improvements of GEO v2016 respect to previous operational SW package MSG v2013 are highlighted in this paper

    NWCSAF GEO v2016 : new products, changes and improvements

    Get PDF
    Ponencia presentada en: 2016 EUMETSAT Meteorological Satellite Conference, 26-30 September 2016, Darmstadt, GermanyThe objective of the Nowcasting Satellite Application Facility (NWC SAF) is the generation of satellite derived products for their direct application to Nowcasting for targeted users. To achieve this goal, the NWC SAF team develops, maintains and distributes software packages that allows the users to generate, at their premises and for the user defined area, satellite derived products with a direct application to Nowcasting. The NWC SAF distributes two different software packages for GEO and LEO satellites. Current operational software package for GEO satellites is MSG v2013, distributed in 2013 and applicable to MSG data. Products generated with MSG v2013 include Cloud Products (Cloud Mask, Cloud Top Temperature and Height, Cloud Type, Cloud phase), Precipitation Products (Probability of Precipitation and Convective Rainfall Rate and Probability of Precipitation and Convective Rainfall Rate from Cloud Microphysics), High Resolution Winds (HRW), Water content and Instability Indices, Automatic Satellite Image Interpretation and detection and tracking of Rapidly Developing Convective Cells. A new software package, GEO v2016, has been distributed in November 2016. Main changes and improvements of GEO v2016 respect to previous operational SW package MSG v2013 are highlighted in this paper
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