4,375 research outputs found
Loss of diversity in the community of small mammals of Doñana National Park (SW Spain): another effect of the local climate change ?
Doñana National Park is an important wetland located in the southwest Spain forming part of the Mediterranean Basin, a "biodiversity hotspot" especially vulnerable to climate change. In this study, we investigate changes in diversity and abundance occurred between 1978 and 2016 in the community of small mammals of Doñana and their relationship with local climate changes. Capture-mark-recapture methods were carried out for a total of 16 years, unevenly distributed over four decades. Our findings show a consistent loss of diversity and abundance decline in the community of small mammals. Eliomys quercinus and Rattus rattus have almost disappeared from the area and Apodemus sylvaticus has sharply reduced its abundance parallel to the progressive increase of Mus spretus. Such a process is worrying for conservation as small mammals represent, after rabbits, the most important prey for carnivores and raptors in Doñana. The detected changes could be at least partially explained by the progressive increase in local temperature observed during the study period. In line with this, the species that have suffered a greater decline are those of Eurasian origin and northern distribution as is the case for E. quercinus and R. rattus while the current dominant species, M. spretus, proceeds from Africa and has a Mediterranean distribution. A non-exclusive alternative is that the extreme rarefaction of rabbits may have caused a trophic cascade effect enhancing predation by carnivores and raptors towards gradually smaller species.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech
Uso de indicadores para evaluar medidas de regulación en la pesquería del pulpo en Yucatán dada la interacción de flotas
Mineralogical and textural characterization of Tartessian ceramics from Ategua (Córdoba, Spain)
El cerro de Teba situado en la Depresión del Guadalquivir, provincia de Córdoba (España), constituye uno de los yacimientos
arqueológicos más interesantes de la época tartésica. En la falda de la colina de Ategua, se han encontrado restos prerromanos
(precoloniales, tartesicos e ibéricos) con algunas estructuras de enterramiento y una gran riqueza de piezas cerámicas.
Cerámicas de época tartésica hechas a torno (fases II y III “orientalizantes”) son las que se estudian en este trabajo. Se ha
estudiado la mineralogía, composición química y la textura de estas piezas para obtener información sobre el posible origen
de las materias primas utilizadas en la fabricación de las cerámicas. Algunos minerales así como los restos de fósiles son
propios de ciertos ambientes, y su detección en las cerámicas permite abordar el origen de las materias primas con que se
elaboraron las piezas. Determinar el origen es siempre uno de los objetivos que se plantea en este tipo de estudios, ya que los
datos sobre las piezas y el entorno ayudan a abordar el problema de la autóctonía o aloctonía de las cerámicasTeba hill, located in the Guadalquivir depression (Córdoba, Spain), is one of the most interesting archaeological deposits from
the Tartessian period. A number of pre-Roman (pre-colonial, Tartessian and Iberian) remains including some burial structures
and a wealth of ceramic pieces have been found on the skirt of the Ategua hill.
In this work, have been studied wheel-thrown ceramic pieces from Phases II and III (orientalizing).
The mineralogical
characteristics, chemical composition and texture of the pieces were used to identify the potential origin of the raw materials
used in their production. Some minerals are as well as fossil remains in fact typical of specific environments, so their presence
in a ceramic piece can help trace the origin of its components. Elucidating the origin of such materials is a common objective
in these studies since accurate information obtained from ceramic pieces and their environment can help one determine
whether they are autochthonous or allochthonous
Mean curvature of spacelike submanifolds in a Brinkmann spacetime
Several geometric properties of complete spacelike submanifolds, with codimension at least two, in a Brinkmann spacetime are shown from natural assumptions involving the mean curvature vector field \mcv of the spacelike submanifold. Especially, we get sufficient conditions that assure that a spacelike submanifold is contained in a leaf of the foliation of the Brinkmann spacetime defined by the orthogonal vectors to the parallel lightlike vector field. When this vector field is the gradient of a smooth function, a characterization of arbitrary codimension spacelike submanifolds contained in a leaf of this foliation is given. In the case of plane fronted wave spacetimes, relevant examples of Brinkmann spacetimes that generalize pp-waves spacetimes, several uniqueness results for codimension two spacelike submanifolds are obtained. In particular, it is proven that any compact codimension two spacelike submanifold with \mcv=0 in a plane fronted spacetime wave must be a (totally geodesic) front of wave.The first author has been partially supported by MINECO/FEDER project MTM2015-65430-P, Fundaci\'on S\'eneca project 19901/GERM/15 and research grant 19783/FPI/15 from Fundaci\'on S\'eneca, the second and the third authors by Spanish MINECO and ERDF project MTM2016-78807-C2-1-P and Andalusian and ERDF project A-FQM-494-UGR1
Contextual intelligence and expertise in soccer
Para los entrenadores la inteligencia en el juego es uno de los intangibles que predicen el éxito en la competición. De ahí que el objetivo de este estudio fuera analizar la percepción que jugadores de fútbol de diferente nivel de pericia tenían de su inteligencia para el juego. Se aplicó el Cuestionario de Inteligencia Contextual en el Deporte (ICD) que evalúa tres dimensiones: Inteligencia Anticipatoria, Inteligencia Táctica e Inteligencia Competitiva. En este estudio participaron 690 jugadores de fútbol de diferente nivel competitivo. Los resultados mostrarion que a medida que aumentaba el nivel competitivo se incrementaba la percepción de los jugadores sobre su inteligencia contextual. Este estudio confirma el papel que para los jugadores posee el sentirse competentes para solucionar los problemas tácticos de su deporte y que este sentimiento aumenta con su nivel de competencia.Coaches consider that game intelligence is one of the main elements that can predict success in competition. The objective of this study was to analize the perceptions that soccer players of different level of expertise had about their intelligence in the field. The Contextual Intelligence Questionnaire (ICD) was applied to a sample of spanish soccer players. This instrument evaluate three dimensions: Anticipatory intelligence, Tactical Intelligence and Competitive Intelligence. Six hundred and ninety of spanish soccer players of different level of expertise, participated in this study. Results showed that this self-perception increased with the level of players. This study confirmed the relevance of feeling able of solving tactical problems in the game, and how this feeling increase with the level of expertise.El presente estudio se pudo llevar a cabo gracias a la ayuda a la investigación concedida por la Cátedra Real Madrid- Universidad Europea de Madrid en su convocatoria 201
Binder chemistry – Low-calcium alkali-activated materials
Early developments in the developments of low-calcium (including calcium-free) alkali-activated binders were led by the work of Davidovits in France, as noted in Chap. 2. These materials were initially envisaged as a fire-resistant replacement for organic polymeric materials, with identification of potential applications as a possible binder for concrete production following relatively soon afterwards [1]. However, developments in the area of concrete production soon led back to more calcium-rich systems, including the hybrid Pyrament binders, leaving work based on the use of low-calcium systems predominantly aimed at high-temperature applications and other scenarios where the ceramic-like nature of clay-derived alkali-activated pastes was beneficial. Early work in this area was conducted with an almost solely commercial focus, meaning that little scientific information was made available with the exception of a conference proceedings volume [2], several scattered publications in other conferences, and an initial journal publication [3]. Academic research into the alkaline activation of metakaolin to form a binder material led to initial publications in the early 1990s [4, 5], and the first description of the formation of a strong and durable binder by alkaline activation of fly ash was published by Wastiels et al. [6-8]. With ongoing developments in fly ash activation, which offers more favourable rheology than is observed in clay-based binders, interest in low-calcium AAM concrete production was reignited, and work since that time in industry and academia has led to the development of a number of different approaches to this problem. A review of the binder chemistry of low-calcium AAM binder systems published in 2007 [9] has since received more than 350 citations in the scientific literature, indicating the high current level of interest in understanding and utilisation of these types of gels
Marginally Trapped Surfaces in the Nonsymmetric Gravitational Theory
We consider a simple, physical approach to the problem of marginally trapped
surfaces in the Nonsymmetric Gravitational Theory (NGT). We apply this approach
to a particular spherically symmetric, Wyman sector gravitational field,
consisting of a pulse in the antisymmetric field variable. We demonstrate that
marginally trapped surfaces do exist for this choice of initial data.Comment: REVTeX 3.0 with epsf macros and AMS symbols, 3 pages, 1 figur
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