6,641 research outputs found

    Life history of plesionika edwardsi (crustacea, decapoda, Pandalidae) around the Canary Islands, Eastern central Atlantic

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    The life history of Plesionika edwardsi (Brandt, 1851) around the Canary Islands in the Eastern Central Atlantic was investigated, based on a total of 11 434 shrimps ranging in length between 8 and 40 mm carapacelength (CL). The species carries out seasonal migrations; they concentrate in deep water during winter, move shallower in summer and return to deep water again in autumn. Ovigerous females occur throughout the year, but a spawning peak was determined between April and September. The size at maturity for females was approximately 26 mm CL. Shrimp size generally increased with increasing water depth. The growth parameters for males were L‡ = 25.75 mm CL and K = 0.55 year-1, and L‡ = 28.28 mm CL and K = 0.66.year-1 for females. The species displays the typical reproductive pattern of tropical pandalids and is dioecious

    Top quark tensor couplings

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    We compute the real and imaginary parts of the one-loop electroweak contributions to the left and right tensorial anomalous couplings of the tbWtbW vertex in the Standard Model (SM). For both tensorial couplings we find that the real part of the electroweak SM correction is close to 10% of the leading contribution given by the QCD gluon exchange. We also find that the electroweak real and imaginary parts for the anomalous right coupling are almost of the same order of magnitude. The one loop SM prediction for the real part of the left coupling is close to the 3σ\sigma discovery limit derived from bsγb\rightarrow s \gamma. Besides, taking into account that the predictions of new physics interactions are also at the level of a few percents when compared with the one loop QCD gluon exchange, these electroweak corrections should be taken into account in order to disentangle new physics effects from the standard ones. These anomalous tensorial couplings of the top quark will be investigated at the LHC in the near future where sensitivity to these contributions may be achieved.Comment: 16 pages, 2 figure

    Creating low-cost soil maps for tropical agriculture using gaussian processes

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    On numerical simulation of powder compaction process: powder transfer modelling and characterisation

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    A numerical model for the powder transfer stage in powder metallurgy cold compaction processes, and the corresponding material characterisation procedure, are proposed. They have been designed on the basis of the following requirements: robust and consistent computational mechanics ingredients, reliability of the obtained results for practical processes in powder metallurgy and industrial viability in the sense that characterisation of any mixture doesn't require either much effort or much time of the enduser. The starting point is a previously developed numerical model for powder compaction, formulated in terms of the large plastic deformation theory, which requires calibration of four parameters controlling the evolution of the yield surface. This calibration, which had been successfully carried out in the past in a range of moderate to high densities, is now extended to very low densities in order to make numerical simulations able to deal with compaction processes involving relevant powder transfer stages. To circumvent the difficulties inherent to direct measurements of very low powder densities, a simple apparatus, which allows studying the powder motion in the chamber, has been designed to provide an indirect way of calibration. On this basis, a set of calibration experiments is proposed. The proposed methodology appears to be simple and industrially viable. Although in the work it is applied to the specific constitutive model used by the authors, it also appears available for other families of constitutive models for powder compaction. As a relevant result, this would allow the same constitutive model to be used, via only the appropriated material characterisation, for simulation of densification in powder transfer stages as well as in pure compaction stage

    A Semantic Web methodological framework to evaluate the support of integrity in thesaurus tools

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    12 p.With the Semantic Web, thesauri recover a relevant role supporting semantic searches and other added-value services. Thesaurus standards define what constructs a thesaurus can have and the integrity rules it must comply with. Thesaurus editors can be helped in their work if thesaurus tools offer them support for integrity, warning when integrity rules are violated and/or helping them to correct these mistakes. The most recent thesaurus standard is ISO 25964, which supersedes ISO 2788, evolving towards concept-based thesauri, better aligned with the Semantic Web approach than the term-based thesauri of ISO 2788. However, the W3C recommendation for KOS (Knowledge Organization System) representation in the semantic web context is SKOS, which is in fact prior to ISO 25964. This paper focuses on thesaurus integrity and the evolution from ISO 2788 to ISO 25964. Its effect on integrity issues is analyzed. A methodological proposal for evaluating integrity support in thesaurus tools, arising from the results of this work, is presented. Its target audience is professionals in charge of thesaurus edition. Besides being adapted to the most recent thesaurus standard, ISO 25964, it also includes the comparison of ISO standards with SKOS. The paper is completed with the presentation of the results of applying it to three thesaurus tools

    A geometric network model of intrinsic grey-matter connectivity of the human brain

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    Network science provides a general framework for analysing the large-scale brain networks that naturally arise from modern neuroimaging studies, and a key goal in theoretical neuro- science is to understand the extent to which these neural architectures influence the dynamical processes they sustain. To date, brain network modelling has largely been conducted at the macroscale level (i.e. white-matter tracts), despite growing evidence of the role that local grey matter architecture plays in a variety of brain disorders. Here, we present a new model of intrinsic grey matter connectivity of the human connectome. Importantly, the new model incorporates detailed information on cortical geometry to construct ‘shortcuts’ through the thickness of the cortex, thus enabling spatially distant brain regions, as measured along the cortical surface, to communicate. Our study indicates that structures based on human brain surface information differ significantly, both in terms of their topological network characteristics and activity propagation properties, when compared against a variety of alternative geometries and generative algorithms. In particular, this might help explain histological patterns of grey matter connectivity, highlighting that observed connection distances may have arisen to maximise information processing ability, and that such gains are consistent with (and enhanced by) the presence of short-cut connections

    Alimentación práctica del cerdo

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    The feed represent over 65% of production costs, so should be established as a priority. It is not enough that a diet meets the nutritional needs of pigs, the ration formulation must right with official regulations governing each country for the use and manufacture of feed. Also, the feed should be easy to preserve and supplying, taking into the wide variety to installations (feeders and drinkers) used in various stages of pigs. However, the fundamental objective of the formulation of a diet is that it contains the necessary nutrients in the correct proportions and balance, considering the physiological stage, weight, age, sex, genetic potential, health status, season and production objectives with a the legal constraints. Once accomplished the formulation, the next step will be insure preparing the feed under conditions that ensure the safety, traceability and lower cost of the same. To this challenge, is adding the need to the right with environmental regulations related to feed and animal welfare.La alimentación representan alrededor del 65% de los costes de producción, por ello debe establecerse como una prioridad. No es suficiente que una dieta cumpla con las necesidades nutricionales de los cerdos, la formulación debe obedecer las normativas oficiales que rigen en cada país para el uso y fabricación de alimentos. Asimismo, el alimento debe ser fácil de conservar y suministrar, asumiendo la gran variedad de instalaciones (comederos y bebederos) utilizadas en las distintas etapas de los cerdos. Sin embargo, el objetivo fundamental de la formulación de una dieta es que contenga los nutrientes necesarios en las cantidades correctas y equilibradas, considerando la etapa fisiológica, peso, edad, sexo, potencial genético, estado de salud, época del año, objetivos productivos y de producto final, así como las limitantes legales. Una vez cumplida la formulación, el siguiente paso es asegurar que ésta sea elaborada bajo condiciones que garanticen la inocuidad, trazabilidad y bajo costo de la misma. A este desafío, se añade la necesidad de cumplir con las normativas ambientales relacionadas con la alimentación y bienestar animal

    Biohydrogen production from diary processing wastewater by anaerobic biofilm reactors

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    Fermentative hydrogen production was studied in packed bed batch reactors to assess the influence of environmental factors over yield hydrogen production from dairy wastewater. Dried stems of Opuntia imbricata were used as substratum adding a pretreated mixed culture for biofilm formation. Experimental results showed that, yield hydrogen production was significantly affected by initial COD concentration, temperature and dairy wastewater pH. Maximum yield obtained was 12.73 mM H2/g CODc when initial COD concentration was 21.1 g COD, dairy wastewater pH with no adjustment (11.32) and room temperature of 16 ± 3°C. Methane production was completely inhibit at an initial pH of 4 at all temperature studied (final pH 4.06), meanwhile, with an initial pH of 11.32, with exception for 16°C, methanogenic activity was not completely inhibit when final pH was over 5, showing an increase in methane production of 0.35 to 0.75 g CH4/l for 35 to 55°C.Key words: Biofilm, dairy wastewater, hydrogen, Opuntia imbricat

    Las IDE como evolución natural de los SIG

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    La IDEE es un proyecto cooperativo, de autoría colectiva, en el que colaboran organismos e instituciones de los tres ámbitos de la Administración (general, regional y local), del entorno universitario y del sector privado. Esta impresionante oferta de información geográfica, junto con las funcionalidades que aportan las tecnologías de Infraestructuras de Datos Espaciales (IDE), permite vislumbrar un abanico de líneas de trabajo, todavía inexploradas, de gran interés para todos los especialistas, técnicos e investigadores que manejan o precisan de cartografía en su quehacer cotidiano, que veremos en el presente artículo
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