526 research outputs found

    Cooperative Simulation Tool with the Energy Management System for the Storage of Electricity Surplus through Hydrogen

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    The INGRID project aims at demonstrating the effective usage of safe, high-density, solid-state hydrogen storage systems for power supply and demand balancing within active power distribution grids with high penetration of intermittent Distributed Generation (Renewable Energy Sources in particular.) The INGRID simulator is divided in two main blocks: the first one represents the Energy Management System, the second one includes the Green Energy Storage System (water electrolyzer, hydrogen solid-storage systems and fuel cell) created to simulate the plant. This paper describes the modules of INGRID simulator and the transient responses of the system for an energy management system virtual according to the power prediction of renewable energy sources, hydrogen demand and the power demand of electric vehiclesEuropean Commission's FP

    Peatlands in the Toledo Mountains (central Spain): characterisation and conservation status.

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    We have limited knowledge about the biodiversity and vulnerability of peatlands in the lower-altitude mountains of the Iberian Peninsula, largely because peatlands have not been routinely differentiated from other habitat types in Spain. Understanding is now developing about the ecology of peatlands in central Spain, but they are already under severe threat of conversion and degradation. In this article we describe the results of a field survey and literature review study to characterise and describe the current condition of peatlands in the Toledo Mountains in terms of their typology, the representation of habitat types protected by European (EU) designations, threats, endangered plant species, and conservation status. Our results suggest that the principal threats are overgrazing by domestic animals and ungulates (red deer and wild boar), fire, expansion of cereal crops, drying-out and erosion. Disturbance is most severe in areas that are not protected by nature conservation designations, where peatlands are especially vulnerable to damage arising from human activities

    Vulnerability and resilience of high-mountain pine forests of the Gredos range (Ávila, Spanish Central System): two thousand years of socio-ecological dynamics

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    RESUMEN: En este trabajo se presenta el análisis palinológico de la turbera de Pozo de la Nieve, localizada en el Parque Natural del Valle de Iruelas (Ávila), un área de alto valor sociocultural dentro de la Sierra de Gredos (Sistema Central). Con el objetivo de relacionar los cambios en el paisaje con la explotación de los recursos naturales y eventos climáticos, en primer lugar se han realizado 7 dataciones radiocarbónicas que sitúan el inicio del registro sedimentario ca. 240 cal BC. Los datos polínicos indican la existencia de un denso pinar altimontano dominado por Pinus sylvestris/nigra desde la Segunda Edad de Hierro hasta el periodo islámico. A partir del periodo cristiano las actividades antrópicas se intensifican, especialmente la ganadería en la Edad Contemporánea, lo cual conlleva la progresiva desaparición del pinar de alta montaña y el desarrollo de pastizales mediante el manejo del fuego, situación que culmina con el desarrollo del paisaje actual dominado por piornales pirófilos.ABSTRACT: We present the palynological study of Pozo de la Nieve peat bog, located in a very valuable socio-cultural placement within the Iruelas Valley Natural Park (Gredos range, Iberian Central System). We have focused in relating landscape changes to natural resources management and climatic events. Firstly, we carried out seven radiocarbon dates suggesting the origin of this record ca. 240 cal BC. The palynological data show the existence of dense high-mountain pine woodlands dominated by Pinus sylvestris/nigra from the Late Iron Age to the Muslim period. Later, from the Christian period, anthropogenic activities have intensified, especially livestock grazing in the Contemporary Age. Its consequences are the progressive disappearance of highmountain pine forests and the extension of grasslands by means of fire, which has shaped current landscape dominated by broom communities.Este trabajo ha sido financiado por el proyecto Desirè-HAR2013-43701-P (Plan Nacional I+D+I, Ministerio de Economía y Competitividad de España). Sebastián Pérez Díaz está financiado por el Programa Estatal de Promoción del Talento y su Empleabilidad en I+D+i en la modalidad Juan de la Cierva-Incorporación. Mónica Ruiz Alonso está financiada por el Programa Estatal de Promoción del Talento y su Empleabilidad en I+D+i en la modalidad Juan de la Cierva-Formación

    Photoelectric Properties of MOS-like Structures with Twofold SRO Films

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    AbstractThe optical properties of silicon rich oxide (SRO) have been deeply studied because, between other reasons, they emit an intense photoluminescence (PL) from visible to the near infrared range when excited with UV light. MOS-like structures with SRO film as the active layer have shown an enhanced conductivity under different illumination conditions. In this paper, MOS-like structures with double SRO layer were fabricated in order to have a barrier to isolate the silicon substrate from the active SRO layer. Results show that all structures have a higher current when light shines on them than that obtained under dark conditions. A possible application of this photo-effect can be used to increase the response of photodetectors and silicon solar cells

    Paleobiogeografía de Abies spp.y Cedrus atlantica en el Mediterráneo occidental (Península Ibérica y Marruecos)

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    RESUMEN: Las especies mediterráneas incluidas en el género Abies, y Cedrus atlantica presentan en la actualidad unas áreas de distribución muy limitadas.En este trabajo, se describen el origen y las rutas migratorias seguidas por Abies pinsapo, A. marocana, A. tazaotana y Cedrus atlantica, desde los inicios del Terciario hasta la actualidad, así como las posibles causas que han llevado a sus poblaciones a su estado actual de aislamiento y peligro de extinción. Abies y Cedrus habrían alcanzado el Mediterráneo Occidental junto con otros elementos de la flora arctoterciaria entre el Eoceno Medio (45 Ma) y el Oligoceno (30 Ma). Posteriormente, experimentaron procesos de especiación hasta fechas relativamente recientes, en los que la apertura del estrecho de Gibraltar (5.33 Ma) habría jugado un papel esencial. A lo largo de las glaciaciones-deglaciaciones del Cuaternario, abetos y cedros mediterráneos habrían permanecido en refugios montañosos del sur de la península ibérica y del norte de África. A pesar de presentar cierta expansión y migración altitudinal coincidiendo con el óptimo térmico del Holoceno Medio, estas especies han sufrido un notable decliveposterior de sus poblaciones, como consecuencia del incremento de la aridez y del impacto de las actividades humanas. El desarrollo de las estrategias de conservación más adecuadas requiere una mejor información sobre la respuesta de estas especies a las distintas perturbaciones, para lo cual resulta indispensable conocer su evolución a lo largo del tiempo. El registro fósil, tanto de macrorrestos como de polen junto a diversos estudios genéticos contribuyen a evaluar su resiliencia y vulnerabilidad.ABSTRACT: The Mediterranean species included in the genus Abies, and Cedrus atlantica show very limited distribution ranges at present. In this work, we outline the origin and migratory routes followed by Abies pinsapo, A. marocana, A. tazaotana and Cedrus atlantica, from the beginning of the Tertiary to the present, as well as the likely causes which have led their populations to their current state of isolation and danger of extinction. Abies and Cedrus would have reached the Western Mediterranean along with other elements of the arctotertiary flora between the Middle Eocene (45 Ma) and the Oligocene (30 Ma). They subsequently underwent speciation processes until relatively recent times, among which the opening of the Strait of Gibraltar (5.33 Ma) would have played an essential role. Mediterranean firs and cedars would have stayed in Southeastern Iberian and North African mountainous refugia during Quaternary glaciations-deglaciations. Despite a noticeable expansion and altitudinal migration in the Mid-Holocene thermal optimum, these species have experienced a further remarkable decline, as a result of the increasing aridity and pressure of human activities. The development of the most appropriate conservation strategies requires the best information on the response of these species to diverse disturbances, thus the knowledge on their temporal evolution becomes essential. The fossil record, both macrorests and pollen, contributes, along with diverse genetic studies, to assessing their resilience and vulnerability

    Charge disproportionation in YNiO3_{3} : ESR and susceptibility study

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    We present a study of the magnetic properties of YNiO3_{3} in the paramagnetic range, above and below the metal-insulator (MI) transition. The dc susceptibility, χdc\chi_{dc} (measured up to 1000 K) is a decreasing function of T for T>T >150 K (the N\'{e}el temperature) and we observe two different Curie-Weiss regimes corresponding to the metallic and insulator phases. In the metallic phase, this behaviour seems to be associated with the small ionic radius of Y% 3+^{3+}. The value of the Curie constant for T<< TMI_{MI} allows us to discard the possibility of Ni3+^{3+} localization. An electron spin resonance (ESR) spectrum is visible in the insulator phase and only a fraction of the Ni ions contributes to this resonance. We explain the ESR and χdc\chi _{dc} behaviour for T << TMI_{MI} in terms of charge disproportionation of the type 2Ni% ^{3+}\to Ni2+^{2+}+Ni4+,^{4+}, that is compatible with the previously observed structural transition across TMI_{MI}.Comment: 10 pages, 4 figures, submitted to Phys. Rev.

    Seis mil años de gestión y dinámica antrópica en el entorno del Parque Natural de los Collados del Asón (Cordillera Cantábrica Oriental)

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    El conocimiento acerca de la evolución de los espacios de montaña resulta ser una problemática de gran interés tanto desde el punto de vista paleoambiental como en relación con las ocupaciones humanas. En este trabajo analizamos la composición y evolución de la vegetación de la turbera de Sotombo, en las cercanías del Parque Natural de los Collados del Asón (Cantabria) en los últimos 6000 años, a través del estudio de pólenes, esporas y microfósiles no polínicos, apoyados por una serie de 8 dataciones radiocarbónicas. Los principales resultados señalan en el inicio de la secuencia el dominio de los bosques caducifolios junto con pinares ca. 5926-2418 cal BP. A partir de este momento se evidencia claramente la antropización del paisaje, en fechas contemporáneas a la expansión de los hayedos. Con posterioridad (desde ca. 596 cal BP) se inicia el desarrollo de las praderas montanas que dominan el paisaje actual.ABSTRACT. The knowledge about the evolution of the mountain areas is a very interesting issue from the palaeoenvironmental stand point, but also from the archaeological view in relation with human occupations. In this paper we analyze the composition and evolution of the vegetation of the peat bog of Sotombo, located in the vicinity of the Collados del Asón Natural Park (Cantabria) over the last 6000 years, through the study of pollens, spores and non-pollen palynomorphs, with the support of 8 AMS radiocarbon dates. The main results point the dominance of deciduous forests with pines between ca. 5926-2418 cal BP. From this moment is clearly evident the anthropogenic activities, in contemporary to the expansion of the beech forests. Subsequently (from ca. 596 cal BP) starts the development of mountain meadows, that dominate the current landscape.Los autores agradecen a los organismos e instituciones que han favorecido el desarrollo de este trabajo, especialmente a la Dirección General de Montes de la Consejería de Desarrollo rural, Ganadería, Pesca y Biodiversidad del Gobierno de Cantabria, por su apoyo financiero y por la ayuda logística a través de la Guardería de Montes y Biodiversidad, y al Plan Nacional I+D+I, CSO2009-14116-CO3-02

    Clostridioides difficile-associated diarrhea in surgical service patients in Mexico

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    Introduction: Clostridium difficile is the first cause of healthcare-associated diarrhea in developed countries. In recent years the incidence of C. difficile infection (CDI) has increased worldwide. There is not much information on the topic in Mexico, and little is known about the risk factors for the infection in patients that are hospitalized in surgical services. Materials and methods: A case-control study was conducted that compared the epidemiologic findings and risk factors between surgical patients with PCR-confirmed CDI, surgical patients with diarrhea and a negative PCR test, and surgical patients with no diarrhea. The statistical analysis was carried out using the SPSS version 22.0 program. Results: The majority of the surgical patients with CDI belonged to the areas of neurosurgery, cardiac surgery, orthopedics, and general surgery. A total of 53% of the CDI cases were associated with the hypervirulent CD NAP1/027 strain. The presence of mucus in stools (OR: 1.5, p = 0.001), fever (OR: 1.4, p = 0.011), leukocytes in stools (OR: 3.2, p < 0.001), hospitalization within the past twelve weeks (OR: 2.0, p < 0.001), antibiotic use (OR: 1.3, p = 0.023), and ceftriaxone use (OR: 1.4, p = 0.01) were independent risk factors for the development of CDI
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