583 research outputs found

    Retos y oportunidades de la implantación de los bancos de agua en España

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    Con el fin de conseguir una buena gobernanza del agua, que trate de alcanzar un equilibrio entre los objetivos de eficiencia económica y sostenibilidad ambiental, durante las últimas décadas se ha potenciado el uso de instrumentos económicos para una mejor gestión de la demanda de los recursos hídricos, dada la dificultad de seguir aumentando la oferta de los mismos. En este contexto, este trabajo se centra en los bancos de agua como mecanismo de mercado que aporta la necesaria flexibilidad institucional en la asignación de los recursos hídricos entre los diferentes usuarios. La investigación realizada en este sentido ha permitido desarrollar una tipología de los bancos de agua que actualmente operan a nivel mundial en base a sus características operativas. Esta caracterización ha permitido igualmente realizar un análisis crítico de las experiencias de bancos de agua implementadas hasta la fecha, con el fin poder valorar el desempeño de este instrumento económico para la mejora de la gestión pública del agua. La investigación llevada a cabo revela que los bancos de agua son un instrumento útil para la gestión de los recursos hídricos, aportando sugerencias para la mejora de su implementación operativa en España mediante la correspondiente reforma de la Ley de Aguas.Ministerio de Economía y Competitividad (MINECO) AGL2013-48080-C2-1-RFondo Europeo de Desarrollo Regional (FEDER) AGL2013-48080-C2-1-

    The variation of the fine structure constant: testing the dipole model with thermonuclear supernovae

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    The large-number hypothesis conjectures that fundamental constants may vary. Accordingly, the space-time variation of fundamental constants has been an active subject of research for decades. Recently, using data obtained with large telescopes a phenomenological model in which the fine structure constant might vary spatially has been proposed. We test whether this hypothetical spatial variation of alpha, which follows a dipole law, is compatible with the data of distant thermonuclear supernovae. Unlike previous works, in our calculations we consider not only the variation of the luminosity distance when a varying alpha is adopted, but we also take into account the variation of the peak luminosity of Type Ia supernovae resulting from a variation of alpha. This is done using an empirical relation for the peak bolometric magnitude of thermonuclear supernovae that correctly reproduces the results of detailed numerical simulations. We find that there is no significant difference between the several phenomenological models studied here and the standard one, in which alpha does not vary spatially. We conclude that the present set of data of Type Ia supernovae is not able to distinguish the standard model from the dipole models, and thus cannot be used to discard nor to confirm the proposed spatial variation of alpha.Peer ReviewedPostprint (published version

    The age-metallicity relation from a sample of white dwarf-main sequence binarie

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    The age-metallicity relation (AMR) is a fundamental observational constraint for un-derstanding how the Galactic disc formed and evolved chemically in time. However, there is not yet an agreement on the observational properties of the AMR, primarily due to the difficulty inobtaining accurate ages for individual field stars. We have started an observational campaign for providing new observational input by using wide white dwarf-main sequence (WDMS) binaries.WDs are natural clocks and can be used to derive accurate ages. Metallicities can be obtained from the MS companions. Since the progenitors of WDs and the MS stars were born at the sametime, WDMS provide a unique opportunity to constrain in a robust way the properties of the AMR. We present the AMR derived from analysing a pilot sample of 23 WDMS and provide clear evidence for the lack of correlation between age and metallicity at young and intermediate ages.Peer ReviewedPostprint (published version

    Una Estrategia Pedagógica para la enseñanza del Lenguaje Visual en estudiantes de Artes y Diseño Gráfico

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    El proyecto alude a un conjunto de actividades que expresaron el dominio de una competencia, en donde el profesor aprendió mediante la observación de alternativas didácticas a fortalecer las debilidades del proceso de enseñanza-aprendizaje en el área de la pedagogía del lenguaje visual

    Impact of power ultrasound on the quality of fruits and vegetables during dehydration

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    Trabajo presentado en el 2015 International Congress on Ultrasonics, celebrado los días 10 a 14 de mayo de 2015 en Metz, FranciaTo date, most of dehydrated vegetables and fruits are obtained by convection preceded or not by a pre-treatment. In general, their quality is low due to the physical modi- fications, loss of vitamins, polyphenols and carbohydrates and Maillard reaction (MR). MR can originate a remarkable loss of nutritional value due to the involvement of lysine. To improve the final quality of these products, one of the alternatives is the application of power ultrasound (US). US produces mechanical effects, such as cavitation, microstream and formation of microscopic channels which facilitate the mass transport and so, the removal of water from the food. The synergistic effect of US and temperature allows carrying out dehydration at low temperatures and short times. In the present work, the influence of power US on the quality of fruits and vegetables during the pre-treatment and drying was evaluated. Chemical indicators such as pectinmethyl esterase and peroxidase enzymes, vitamin C, carbohydrates, proteins, polyphenols and 2-furoylmethylamino acids was studied. In addition, rehydration capacity, leaching losses, shrinkage and organoleptic characteristics of the final product was assessed. During blanching, similar leaching losses and enzyme inactivation were found in low temperature and prolonged conventional treatments and in US processes, but with a significant reduction in the time for the latter. Application of US in the drying of carrots and strawberries provided high-quality end-products. The quality was better as compared to marketed products and superior or equivalent to samples obtained in a convective dryer, and, in some indicators, similar to that of freeze-dried samples.Peer reviewe

    The initial–final mass relationship of white dwarfs in common proper motion pairs and open clusters

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    We have studied white dwarfs in common proper motion pairs (CPMPs) to improve the semi-empirical initial–final mass relationship of white dwarfs. In this contribution, we re- port new results obtained from spectroscopic observations of both members of several CPMPs composed of a F, G or K type star and a DA white dwarf.Peer Reviewe

    Disposable Electrochemical Biosensor Based on the Inhibition of Alkaline Phosphatase Encapsulated in Acrylamide Hydrogels

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    The present work describes the development of an easy-to-use portable electrochemical biosensor based on alkaline phosphatase (ALP) as a recognition element, which has been immobilized in acrylamide-based hydrogels prepared through a green protocol over disposable screen-printed electrodes. To carry out the electrochemical transduction, an electroinactive substrate (hydroquinone diphosphate) was used in the presence of the enzyme and then it was hydrolyzed to an electroactive species (hydroquinone). The activity of the protein within the matrix was determined voltammetrically. Due to the adhesive properties of the hydrogel, this was easily deposited on the surface of the electrodes, greatly increasing the sensitivity of the biosensor. The device was optimized to allow the determination of phosphate ion, a competitive inhibitor of ALP, in aqueous media. Our study provides a proof-of-concept demonstrating the potential use of the developed biosensor for in situ, real-time measurement of water pollutants that act as ALP inhibitors.This research was funded by Ministerio de Ciencia e Innovación (projects PID2019-105923RB-I00, PDC2021-120884-I00, European Union NextGenerationEU PRTR-C17.I1) and Generalitat Valenciana (project GVA-THINKINAZUL/2021/015 and PROMETEO/2018/087)

    FIRI - a Far-Infrared Interferometer

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    Half of the energy ever emitted by stars and accreting objects comes to us in the FIR waveband and has yet to be properly explored. We propose a powerful Far-InfraRed Interferometer mission, FIRI, to carry out high-resolution imaging spectroscopy in the FIR. This key observational capability is essential to reveal how gas and dust evolve into stars and planets, how the first luminous objects in the Universe ignited, how galaxies formed, and when super-massive black holes grew. FIRI will disentangle the cosmic histories of star formation and accretion onto black holes and will trace the assembly and evolution of quiescent galaxies like our Milky Way. Perhaps most importantly, FIRI will observe all stages of planetary system formation and recognise Earth-like planets that may harbour life, via its ability to image the dust structures in planetary systems. It will thus address directly questions fundamental to our understanding of how the Universe has developed and evolved - the very questions posed by ESA's Cosmic Vision.Comment: Proposal developed by a large team of astronomers from Europe, USA and Canada and submitted to the European Space Agency as part of "Cosmic Vision 2015-2025

    Los retos del país y los aportes de la Contaduría Pública

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    El presente escrito pretende demostrar la importancia que la investigación debe tener en una profesión como la Contaduría Pública para facilitar el desarrollo de cualquier tipo de organización tanto pública como privada; y cómo ésta (la investigación) puede ser factor decisivo para asumir con responsabilidad y solidez los retos que la sociedad actual le impone al profesional de esta área
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