1,148 research outputs found

    Sustainable Planning of Land Use Changes in farming areas under ecological protection

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    Land use has been changing in the last decades because of agricultural intensification and land abandonment which implies deterioration in the optimum habitat structure and quality. Habitat degradation and loss, resulting from changes in land use remain significant drivers of biodiversity loss. These trends are widely recognised and have forced national and international agencies to identify protected sites for natural areas with high biodiversity value. Special Protection Areas (SPAs) are natural zones particularly relevant for nature conservation. Regional planning is bound to play an increasing role in nature conservation policies because much biodiversity is located in farming areas outside natural parks. Agriculture in the Mediterranean Basin has always been highly dependent on rainfed crops, cereal, vine and olive. Vine growing plays an important role not only from the economic point of view, but also environmentally as a permanent plant cover in terms of preventing erosion, managing land and water resources in a sustainable way, defending against desertification an settling population in rural areas. A Geographic Information System (GIS) was used to implement a decision tool system to analyse the feasibility of new proposals to upgrade traditional vineyards in Castilla-La Mancha, Spain. The study focuses on the sustainability of current farming practices in Special Protection Areas for Steppe Land Birds. This paper presents a model to quantify the resulting habitat fragmentation basing on infrastructure facilities, leading to mapping areas where to apply restriction measures to prevent physical destruction of the habita

    Welbeck estate. Desde las entrañas de la tierra John Cavendish-Scott-Bentinck, 5th Duque de Portland (1800-1879)

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    Esta es la historia de una ciudad transformada desde las entrañas de la tierra, un más allá donde las leyes de la razón quedan en suspenso. Una especie de “otra naturaleza”, entendida como un inmaterial desconocido con el que reflexionar sobre la hipótesis de que toda ciudad contiene en sus dobleces un mundo natural. Este ensayo es un posicionamiento, un dialogo en torno a esta singular relación entre ciudad y naturaleza; una reflexión sobre la forma en que las cosas ocurren en el espacio, y aquellas que suceden en el tiempo. Espacios y tiempos desdoblados y plegados sobre sí mismos, como inmateriales con los que el 5th duque construyó esta fascinante escenografía en la que representar su propia vida.The life of the 5th Duke of Portland is the story of the obsession with finding a spot of quiet, a zone free of worry, a place to feel safe. Perhaps he found there, in that natural and unfolded space of the visible world, the forces to overcome his difficulty, to understand the scale of space; that is, the way in which others establish relationships of similarity, distance or closeness with oneself. Following his appointment as heir to this immense state, almost immediately began a series of investments of an unprecedented scale, which have been considered, technically and conceptually, pioneers in the domestic and landscape transformations of the nineteenth century. Welbeck Estate is a double city, one visible and the other hidden, one in surface, constructed with physical materials; the other less obvious, submerged between shadows and natural substances, flows, energies, scales, processes and senses.This is the story of a city transformed from the bowels of the earth, beyond where the laws of reason are suspended. A kind of “other nature”, understood as an immaterial unknown with which to reflect on the way things happen in space, and those that happen in time. Spaces and times unfolded and folded over themselves, as materials with which the 5th Duke built this fascinating scenery in which to represent his own life

    GWpilot: Enabling multi-level scheduling in distributed infrastructures with GridWay and pilot jobs

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    Current systems based on pilot jobs are not exploiting all the scheduling advantages that the technique offers, or they lack compatibility or adaptability. To overcome the limitations or drawbacks in existing approaches, this study presents a different general-purpose pilot system, GWpilot. This system provides individual users or institutions with a more easy-to-use, easy-toinstall, scalable, extendable, flexible and adjustable framework to efficiently run legacy applications. The framework is based on the GridWay meta-scheduler and incorporates the powerful features of this system, such as standard interfaces, fair-share policies, ranking, migration, accounting and compatibility with diverse infrastructures. GWpilot goes beyond establishing simple network overlays to overcome the waiting times in remote queues or to improve the reliability in task production. It properly tackles the characterisation problem in current infrastructures, allowing users to arbitrarily incorporate customised monitoring of resources and their running applications into the system. This functionality allows the new framework to implement innovative scheduling algorithms that accomplish the computational needs of a wide range of calculations faster and more efficiently. The system can also be easily stacked under other software layers, such as self-schedulers. The advanced techniques included by default in the framework result in significant performance improvements even when very short tasks are scheduled

    Disentangling the metallicity and star formation history of HII galaxies through tailor-made models

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    We present a self-consistent study of the stellar populations and the ionized gas in a sample of 10 HII galaxies with, at least, four measured electron temperatures and a precise determination of ionic abundances following the "direct method". We fitted the spectral energy distribution of the galaxies using the program STARLIGHT in order to quantify the contribution of the underlying stellar population to EW(Hbeta), which amounts to about 10% for most of the objects. We then studied the Wolf-Rayet stellar populations detected in seven of the galaxies. The presence of these populations and the corrected EW(Hbeta) values indicate that the ionizing stellar populations were created following a continuous star formation episode of 10 Myr duration, hence WR stars may be present in all of objects even if they are not detected in some of them. The derived stellar features, the number of ionizing photons and the relative intensities of the strongest emission lines were used as input parameters to compute tailored models with the photoionization code CLOUDY. Our models are able to y reproduce their thermal and ionization structure as deduced from their collisionally excited emission lines and, hence, no abundance discrepancy factors are implied for this kind of objects. Only the electron temperature of S+ is overestimated by the models, pointing to the possible presence of outer shells of diffuse gas in these objects. This kind of geometrical effects can affect the determination of the equivalent effective temperature of the ionizing cluster using calibrators which depend on low-excitation emission lines.Comment: 20 pages, 12 figures, MNRAS (in press

    Heat transfer with phase change in a shell and tube latent heat storage unit

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    Paper presented to the 10th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Florida, 14-16 July 2014.Concerning thermal energy storage, latent heat thermal energy storage is particularly attractive technique because it provides a high energy storage density. The development of a latent heat thermal energy storage system therefore involves first the understanding of heat transfer in the phase change materials (PCM) when they undergo solid-to-liquid phase transition in the required operating temperature range, and second, the design of the container for holding the PCM and the formulation of the phase change problem. The paper presents a study on the heat transfer mode of a PCM stored in a horizontal cylindrical shell and tube heat exchanger, being the PCM placed inside the tubes. For this purpose, an experimental bench has been developed to test the heat transfer process, coupled with a Ground-Source Heat Pump (GSHP), controlled by a computer program developed to manage the coupled GSHP+PCM system. The aim is to compute the heat transfer of the installation during the loading, storage and downloading energy processes. More precisely, the interest is to check experimentally to what extent some common hypothesis used for heat transfer calculations are valid or not. In particular: (i) Comparison between the radial and the axial heat transfer through the wall of the PCM tube; (ii) The temperature distribution of the heat transfer fluid in the central and peripheral locations; (iii) The heat transfer rate between the container and the ambient temperature. Results indicate that density gradients could occur during energy exchange between the heat transfer fluid and the PCM when melting or solidification are taking place, leading to modification of central flow with respect to peripheral flow. Also, the temperature gradients recorded in the axial direction during the change of phase were very small compared with those of that of the radial direction, indicating essentially a two-dimensional heat transfer mode.dc201

    High resolution spectroscopy of the BCD galaxy Haro 15: II. Chemodynamics

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    We present a detailed study of the physical properties of the nebular material in four star-forming knots of the blue compact dwarf galaxy Haro 15. Using long-slit and echelle spectroscopy obtained at Las Campanas Observatory, we study the physical conditions (electron density and temperatures), ionic and total chemical abundances of several atoms, reddening and ionization structure, for the global flux and for the different kinematical components. The latter was derived by comparing the oxygen and sulphur ionic ratios to their corresponding observed emission line ratios (the η\eta and η\eta' plots) in different regions of the galaxy. Applying the direct method or empirical relationships for abundance determination, we perform a comparative analysis between these regions. The similarities found in the ionization structure of the different kinematical components implies that the effective temperatures of the ionizing radiation fields are very similar in spite of some small differences in the ionization state of the different elements. Therefore the different gaseous kinematical components identified in each star forming knot are probably ionized by the same star cluster. However, the difference in the ionizing structure of the two knots with knot A showing a lower effective temperature than knot B, suggests a different evolutionary stage for them consistent with the presence of an older and more evolved stellar population in the first.Comment: 21 pages, 6 figures, 8 tables, accepted by MNRA

    Influence of environmental factors on the reproductive cycle of the eared ark Anadara notabilis (Röding, 1798) in Northeastern Venezuela

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    5 figuras, 2 tablasThe reproductive cycle of the eared ark Anadara notabilis and its relationship with environmental factors was evaluated every 15 days between March 2004 and February 2005 at the northern part of the Peninsula de Araya, Venezuela. Environmental factors measured included temperature, salinity, chlorophyll a, and total seston, including the particulate organic matter and particulate inorganic matter fractions. Adult specimens were collected using a net drag and then randomly selected to estimate wet live biomass and dry biomass of soft body tissues. Gonad samples were processed with histological analysis to determine sex ratio, developmental stages, and variations of follicle size. Reproduction in A. notabilis was continuous throughout the year, with spawning peaks occurring in June and October, coinciding with the lowest water temperatures. In March, September, and November 2004, specimens attained the highest dry biomass values, whereas lowest dry biomass occurred in June and October 2004. Stepwise regression analyses demonstrated that temperature and particulate organic matter values are the main modulators of reproductive events. When temperature decreased, dribble spawning was detected in this species, possibly inducing a survival strategy whereby the spawning period is extended to increase reproductive successPeer reviewe

    Integral field spectroscopy of nitrogen overabundant blue compact dwarf galaxies

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    We study the spatial distribution of the physical properties and of oxygen and nitrogen abundances in three Blue Compact Dwarf Galaxiess (HS 0128+2832, HS 0837+4717 and Mrk 930) with a reported excess of N/O in order to investigate the nature of this excess and, particularly, if it is associated with Wolf-Rayet (WR) stars We have observed these BCDs by using PMAS integral field spectroscopy in the optical spectral range (3700 - 6900 {\AA}), mapping their physical-chemical properties, using both the direct method and appropriate strong-line methods. We make a statistical analysis of the resulting distributions and we compare them with the integrated properties of the galaxies. Our results indicate that outer parts of the three galaxies are placed on the "AGN-zone" of the [NII]/H{\alpha} vs. [OIII]/H{\beta} diagnostic diagram most likely due to a high N/O combined with the excitation structure in these regions. From the statistical analysis, it is assumed that a certain property can be considered as spatially homogeneous (or uniform) if a normal gaussian function fits its distribution in several regions of the galaxy. Moreover, a disagreement between the integrated properties and the mean values of the distribution usually appears when a gaussian does not fit the corresponding distribution. We find that for Mrk 930, the uniformity is found for all parameters, except for electron density and reddening. The rotation curve together with the H{\alpha} map and UV images, reveal a perturbed morphology and possible interacting processes. The N/O is found to be constant in the three studied objects at spatial scales of the order of several kpc so we conclude that the number of WR stars estimated from spectroscopy is not sufficient to pollute the ISM and to produce the observed N/O excess in these objectsComment: 17 pages, 14 figures, accepted for publication in Astronomy & Astrophysic

    La autopercepción del esfuerzo y recuperación en el arbitraje profesional español: un estudio de caso

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    El propósito de este estudio es conocer la percepción de esfuerzo y recuperación de un árbitro profesional perteneciente a la máxima catego- ría del fútbol español. Para ello, se han analizado 17 partidos de la primera división del fútbol español (Liga BBVA) durante la temporada 2012-13 en los que fue designado como árbitro principal. Conjuntamente, se preten- de comprobar la inuencia de la dicultad de cada encuentro sobre estos parámetros, categorizada según la clasicación previa de los equipos. Para el análisis de la percepción de esfuerzo se han empleado las escalas RPE (Rating Perceived Exertion) de Borg y la escala CR10 de Borg modicada (Category scales with Ratio properties) mientras que, para la percepción de la recuperación, se ha empleado la escala TQR (Total Quality Recovery). Los valores promedio obtenidos muestran que la percepción del esfuerzo realizado durante el arbitraje, con independencia de la escala empleada y la dicultad de los encuentros, es de “duro” (CR10, 5,8 ± 1,3; RPE, 14,6 ± 0,9). La percepción de la recuperación, transcurridas 24 horas del encuen- tro, es percibida como “razonable” (13,7 ± 0,8).
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