200 research outputs found

    The Coester Line in Relativistic Mean Field Nuclear Matter

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    The Walecka model contains essentially two parameters that are associated with the Lorentz scalar (S) and vector (V) interactions. These parameters are related to a two-body interaction consisting of S and V, imposing the condition that the two-body binding energy is fixed. We have obtained a set of different values for the nuclear matter binding energies at equilibrium densities. We investigated the existence of a linear correlation between BNB_N and ρ0\rho_0, claimed to be universal for nonrelativistic systems and usually known as the Coester line, and found an approximate linear correlation only if V?SV?S remains constant. It is shown that the relativistic content of the model, which is related to the strength of V?SV?S, is responsible for the shift of the Coester line to the empirical region of nuclear matter saturation.Comment: 7 pages, 5 figure

    Facilitating Building Information Modelling (BIM) using Integrated Project Delivery (IPD): A UK perspective

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    The Construction industry is a major player in the UK economy and is in need of continuous improvement. In an attempt to do so, in 2011 the UK government made Building Information Modelling (BIM) level 2 a mandate for all public projects by 2016. Integrated Project Delivery (IPD) is a project delivery approach closely attributed to BIM. However, it does not seem to have received proportionate level of attention and uptake in the UK

    High Resilience of Seed Dispersal Webs Highlighted by the Experimental Removal of the Dominant Disperser

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    The pressing need to conserve and restore habitats in the face of ongoing species loss [1, 2] requires a better understanding of what happens to communities when species are lost or reinstated [3, 4]. Theoretical models show that communities are relatively insensitive to species loss [5, 6]; however, they disagree with field manipulations showing a cascade of extinctions [7, 8] and have seldom been tested under field conditions (e.g., [9]). We experimentally removed the most abundant seed-dispersing ant species from seed dispersal networks in a Mediterranean landscape, replicating the experiment in three types of habitat, and then compared these communities to un-manipulated control communities. Removal did not result in large-scale changes in network structure. It revealed extensive structural plasticity of the remaining community, which rearranged itself through rewiring, while maintaining its functionality. The remaining ant species widened their diet breadth in a way that maintained seed dispersal, despite the identity of many interactions changing. The species interaction strength decreased; thus, the importance of each ant species for seed dispersal became more homogeneous, thereby reducing the dependence of seed species on one dominant ant species. Compared to the experimental results, a simulation model that included rewiring considerably overestimated the effect of species loss on network robustness. If community-level species loss models are to be of practical use in ecology or conservation, they need to include behavioral and population responses, and they need to be routinely tested under field conditions; doing this would be to the advantage of both empiricists and theoreticians

    Dietary protein, growth, nutrient utilization and body composition of juvenile blackspot seabream, Pagellus bogaraveo (Brunnich)

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    When considering new marine species for Mediterranean aquaculture, blackspot seabream emerges as a potential candidate. However, there are scarce data on the nutritional requirements and optimal growth conditions of this species. A 12-week feeding trial was conducted to evaluate the effects of dietary protein on growth, nutrient utilization and body composition of blackspot seabream (23 g). Five isolipidic diets (12%) with graded levels of protein (20-60%) were distributed, twice a day, to duplicate groups of fish, until satiation. Growth increased significantly with increasing dietary protein up to 40%, but higher protein levels induced a similar daily growth index (1.4). Feed conversion ratio (FCR) decreased with increasing levels of dietary protein (4.2-1.6). No significant differences were detected in protein of whole body blackspot seabream among treatments, but fat percentage decreased with increasing dietary protein. Dry matter and energy digestibility showed a concomitant increase with the reduction in dietary wheat meal, attaining maximal values with high protein diets. These results suggested that the most favourable values for growth and FCR are obtained with diets containing 40% protein. However, the excessive lipid deposition reveals that more nutritional studies are necessary before the species can be established in aquaculture

    Screening the Pathogen Box for Identification of New Chemical Agents with Anti-Fasciola hepatica Activity

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    Fascioliasis is an infectious parasitic disease distributed globally and caused by the liver fluke Fasciola hepatica or F. gigantica. This neglected tropical disease affects both animals and humans, and it represents a latent public health problem due to the significant economic losses related to its effects on animal husbandry. For decades, triclabendazole has been the unique anti-Fasciola drug that can effectively treat this disease. However, triclabendazole resistance in fascioliasis has more recently been reported around the world, and thus, the discovery of novel drugs is an urgent need. The aim of this study was to investigate the fasciocidal properties of 400 compounds contained in the Pathogen Box. The first stage of the screening was carried out by measuring the fasciocidal activity on metacercariae at a concentration of 33 mu M each compound (the standard dose). Subsequently, the activities of the most active compounds (n = 33) at their 50% inhibitory concentration (IC50) values against metacercariae were assayed, and the results showed that 13 compounds had IC(50)s of 50%. Four hit compounds were selected on the basis of their predicted nontoxic properties, and the IC50 values obtained for adult worms were <10 mu M; thus, these compounds represented the best fasciocidal compounds tested here. A cytotoxicity assay on four types of cell lines demonstrated that three compounds were nontoxic at their most active concentration. In conclusion, three hit compounds identified in this proof-of-concept study are potential candidates in the discovery of new fasciocidal drugs. Further studies are warranted

    MOGEDA : Modelo Genérico de Desensamblado Automático

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    El desensamblado de productos es la clave del proceso de reciclado. En este artículo se plantea el modelado del proceso de desensamblado automático de productos. Se estudian, tanto los requerimientos necesarios para poder abordar el proceso de forma automática, como las herramientas necesarias para poderlo llevar a cabo: base de conocimiento basada en modelos y técnicas de reconocimiento y localización tridimensional de objetos mediante visión artificial.Tanto los trabajos realizados como los futuros están enmarcados en el proyecto de la CICYT “Sistema Robotizado de Desensamblado Automático basado en Modelos y Visión Artificial” (TAP1999-0436)

    VISUAL : herramienta para la enseñanza práctica de la visión artificial

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    En este artículo se presenta un enfoque práctico para la enseñanza de la visión artificial en la asignatura de “Robots y Sistemas Sensoriales” impartida por el área de Ingeniería de Sistemas y Automática en la Universidad de Alicante. En primer lugar, se describe la herramienta VISUAL que ha sido desarrollada por miembros del grupo de Automático, Robótica y Visión Artificial y que permite al alumno especificar un algoritmo de procesamiento de imágenes mediante un esquema gráfico formado por un conjunto de diferentes módulos básicos de procesamiento. Así, la herramienta VISUAL proporciona un interfaz para la visión artificial de manejo intuitivo, al mismo tiempo que permite desarrollos de algoritmos fácilmente comprensibles gracias a su escalabilidad y modularidad, posibilitando realizar etapas de procesamiento claramente definidas. Además, se comentan algunos de los experimentos prácticos propuestos y desarrollados haciendo uso de VISUAL y destinados al reconocimiento y localización de objetos para su posterior manipulación con un robot

    Virtual remote laboratory for teaching of computer vision and robotics in the University of Alicante

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    Comunicación presentada en IBCE'04, Second IFAC Workshop on Internet Based Control Education, 5-7 septiembre 2004, Grenoble, FranciaIn this article, we describe the virtual and remote laboratory for computer vision and robotics education at the University of Alicante (Spain). Its aims are to provide access for all the students to the available robotic and computer vision equipments, generally limited, due to its high cost
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