480 research outputs found

    Multiple, solid evidence support that Austropotamobius italicus is not native to Spain

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    Climate Change or Land Use Dynamics: Do We Know What Climate Change Indicators Indicate?

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    Different components of global change can have interacting effects on biodiversity and this may influence our ability to detect the specific consequences of climate change through biodiversity indicators. Here, we analyze whether climate change indicators can be affected by land use dynamics that are not directly determined by climate change. To this aim, we analyzed three community-level indicators of climate change impacts that are based on the optimal thermal environment and average latitude of the distribution of bird species present at local communities. We used multiple regression models to relate the variation in climate change indicators to: i) environmental temperature; and ii) three landscape gradients reflecting important current land use change processes (land abandonment, fire impacts and urbanization), all of them having forest areas at their positive extremes. We found that, with few exceptions, landscape gradients determined the figures of climate change indicators as strongly as temperature. Bird communities in forest habitats had colder-dwelling bird species with more northern distributions than farmland, burnt or urban areas. Our results show that land use changes can reverse, hide or exacerbate our perception of climate change impacts when measured through community-level climate change indicators. We stress the need of an explicit incorporation of the interactions between climate change and land use dynamics to understand what are current climate change indicators indicating and be able to isolate real climate change impacts

    Los peces continentales de la provincia de Cádiz

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    La ictiofauna continental de la provincia de Cádiz está constituida por 18 especies, de las que 12 son autóctonas y cinco autóctonas estrictamente de agua dulce. Esto significa que más del 50% de las especies de peces estrictamente dulceacuícolas que habitan la provincia son introducidas. Ello contrasta con que de las cinco autóctonas tres son prácticamente endémicas de las cuencas gaditanas (cachuelo, colmilleja y fartet serán descritas en un futuro próximo como nuevas especies para la ciencia). Es decir, la ictiofauna gaditana posee un elevado grado de endemicidad y por tanto un valor de conservación igualmente alto. Esto contrasta con la delicada situación que atraviesan estas mismas especies. Considerados en conjunto, los cursos de agua que surcan la provincia de Cádiz poseen el mayor valor de conservación, basado en los peces, de todos los de la mitad meridional de España. De entre todos ellos destaca el Hozgarganta, que está considerado como el río mejor conservado de toda España, en cuanto al valor de su ictiofauna se refiere. La ictiofauna típica de un río gaditano estaría formada por tres especies: barbo, boga y cachuelo. Estas especies se distribuyen de manera muy desigual a lo largo del curso de los ríos y dentro de tramos específicos tienden a agruparse configurando distribuciones también heterogéneas. Las razones de esta desigual distribución no son bien conocidas, si bien al menos parcialmente, pudieran estar relacionadas con la degradación de los ríos por las actividades humanas. Entre los peces gaditanos más amenazados se encuentra el fartet. Esta especie posee unos requerimientos ecológicos muy estrictos que le obligan a ocupar ambientes muy precisos y escasos. En apariencia esta especie, que necesita de medios acuáticos permanentes, no tolera bien la presencia de otros peces por lo que está obligada a ocupar ambientes extremos donde no puede sobrevivir ninguna otra especie. La conservación de los fartets ha de hacerse a la luz de esta circunstancia. La ictiofauna que habitó en la antigua laguna de La Janda es hoy casi un enigma. Sin embargo, estudios recientes han puesto de manifiesto que en el bajo Barbate aún existe una comunidad diversa y muy productiva que apunta a que en La Janda podría haber existido una comunidad más rica aún y al menos igualmente productiva. También los pequeños cursos de agua del entorno de Tarifa poseen una ictiofauna peculiar, si bien muy amenazada por la fragilidad de estos pequeños ecosistemas

    Dependability assessment of by-wire control systems using fault injection

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    This paper is focused on the validation by means of physical fault injection at pin-level of a time-triggered communication controller: the TTP/C versions C1 and C2. The controller is a commercial off-the-shelf product used in the design of by-wire systems. Drive-by-wire and fly-by-wire active safety controls aim to prevent accidents. They are considered to be of critical importance because a serious situation may directly affect user safety. Therefore, dependability assessment is vital in their design. This work was funded by the European project `Fault Injection for TTA¿ and it is divided into two parts. In the first part, there is a verification of the dependability specifications of the TTP communication protocol, based on TTA, in the presence of faults directly induced in communication lines. The second part contains a validation and improvement proposal for the architecture in case of data errors. Such errors are due to faults that occurred during writing (or reading) actions on memory or during data storage.Blanc Clavero, S.; Bonastre Pina, AM.; Gil, P. (2009). Dependability assessment of by-wire control systems using fault injection. Journal of Systems Architecture. 55(2):102-113. doi:10.1016/j.sysarc.2008.09.003S10211355

    A New Methodology for Assessing the Interaction between the Mediterranean Olive Agro-Forest and the Atmospheric Surface Boundary Layer

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    Historically, the olive grove has been one of the most emblematic ecosystems in Mediterranean countries. Currently, in Andalusia, Spain, the land under olive grove cultivation exceeds 1.5 million hectares, approximately 17% of the regional surface. Its exploitation has traditionally been based on the use of the available land and heterogeneous plantations, with different species adapted to southern Mediterranean climatic conditions, and to the management of the traditional olive cultivation culture. The objective of this work is to characterize the mechanical behavior of the atmospheric surface boundary layer (SBL) (under neutral stability) interacting with different olive grove configurations. Experimental tests were carried out in the Boundary Layer Wind Tunnel (BLWT) of the Andalusian Institute for Earth System Research (IISTA), University of Granada. Three representative configurations of olive groves under neutral atmospheric conditions were tested. The wind flow time series were recorded at several distances and heights downwind the olive plantation models with a cross hot wire anemometry system. Herein, this paper shows the airflow streamwise, including the mean flow and the turbulent characteristics. The spatial variability of these two mechanical magnitudes depends on, among others, the size, the agro-forest length, the layout of the tree rows, the porosity, the tree height, the crown shape and the surface vegetation cover. The aerodynamic diameter and Reynolds number for each agro-forest management unit are proposed as representative variables of the system response, as these could be related to olive grove management. The plantation, in turn, conforms to a windbreak, which affects the microclimate and benefits the elements of the ecosystem. Detailed knowledge of these variables and the interaction between the ecosystem and the atmosphere is relevant to optimize the resources management, land use and sustainability of the overall crop. Thus, this paper presents preliminary work to relate atmospheric variables to environmental variables, some of which could be humidity, erosion, evapotranspiration or pollen dispersion.“Proyectos de Investigación Precompetitivos para Jóvenes Investigadores” from the University of Granad

    Bulk Wave Dissipation in the Armor Layer of Slope Rock and Cube Armored Breakwaters

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    The authors wish to acknowledge Thomas Lykke Andersen for allowing performing laboratory tests in the wave flume of Aalborg University.The objective of this research is to analyze the interaction of the incident wave train with a mound breakwater (specifically, dissipation in the armor layer) and to quantify the performance of the structure built with different types and sizes of armor units. The generalized Π -Buckingham theorem is invoked to choose a complete set of independent variables that govern the principal interaction processes. The analysis is based on two sets of experimental data obtained in the wave flume of IISTA, University of Granada, and in the wave flume of Aalborg University. The bulk dissipation depends on the product of the relative water depth and the incident wave steepness, (h/L)(HI/L), the relative size of the armor diameter, Da/HI, the relative thickness, e/L, the shape and specific placement criterion, the characteristics of the porous core, B∗/L, D50,p/L, and the slope angle of the breakwater. For a given breakwater, the product of (h/L)(HI/L) can be used to identify and quantify three hydrodynamic performance regimes: reflective, dissipative and transitional, based on the prevalent interaction processes. Moreover, the dimensional analysis provides a functional relationship between the stability parameter and the bulk dissipation. For two mound breakwaters, one built with cubes of Da=49.6 mm and the other one with rocks of Da=44.0 mm, the bulk dissipation is almost similar over the entire range of (h/L)(HI/L). These results could be useful for the assimilation of data obtained in different wave flumes, the optimization of the breakwater design and to revise the notional permeability parameter.Spanish Ministry of Economy and Business (project "Integrated verification of the hydrodynamic and structural behaviour of a breakwater and its implications on the investment project-VIVALDI") BIA2015-65598-P"Programa Iberoamericano de Ciencia y Tecnologia para el Desarrollo", CYTED (project "Protection of coastal urban fronts against global warming-PROTOCOL") 917PTE0538Junta de Andalucía TEP-209Spanish Ministry of Education, Culture and Sports FPU14/0357

    Invariants of Turbulence Reynolds Stress and of Dissipation Tensors in Regular Breaking Waves

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    A series of measurements in a flume with a particle-tracking system in three dimensions applied to breaking waves is used to analyse the structure of turbulence with a full set of variables that usually are available only in numerical simulations. After extracting turbulence, in addition to the standard analysis aiming to quantify the fluxes, i.e., the time-average and the phase-average levels of turbulence and vorticity (details are given in two former papers), a more in-depth description of the structure of turbulence Reynolds stress tensor is given, focussing on the invariants evolution in time and in the vertical. A relation between the components of the Reynolds stress tensor and of the dissipation tensor is depicted. This relation is finalised to possible models of turbulence in breaking waves

    EU's conservation efforts need more strategic investment to meet continental commitments

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    The European Union (EU) has made significant conservation efforts in the last two decades, guided by the Birds and Habitats Directives, currently under evaluation. Despite these efforts a large proportion of priority species are still in unfavorable condition and continue declining. For this reason, a thoughtful review of the implementation of conservation efforts in Europe is needed to identify potential causes behind this poor effectiveness. We compiled information on the distribution of all conservation funds under the LIFE‐Nature, the main financial tool for conservation in Europe. We found that LIFE‐Nature has not adequately covered continental conservation needs. The majority of funds have been directed toward nonthreatened species or regions of low conservation priority. Given the limited resources available, two key aspects are in urgent need for revision and improvement. First, the distribution of funds should be guided by continental and global conservation needs and planned at the EU scale. Second, new mechanisms are required to set conservation priorities in a dynamic fashion, rather than relying on fixed lists (i.e., the Directives’ Annexes) that may rapidly become outdated. These improvements would require new mechanisms to set priorities and redistribution of conservation efforts, supported by adequate policy and a more effective top‐down control on investment.V.H. and M.C. were supported by two Ramón y Cajal contracts funded by the Spanish Ministry of Science and Innovation (RYC‐2013‐13979 and RYC‐2010‐06431, respectivey)
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