1,825 research outputs found

    Copernicus observations of Betelgeuse and Antares

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    Copernicus observations of the M-supergiants, alpha Ori and alpha Sco, are presented. The MgII h and k resonance lines are strongly in emission in both stars. The k line is highly asymmetric in both stars but the h line is symmetric. Upper limits for several other resonance lines are given for alpha Ori. The possibility is explored that the k line asymmetry is caused by overlying resonance lines of MnI and FeI formed in the cool circumstellar gas shells around these stars. Observations of the MnI 4030-4033 A lines are used to show that circumstellar shell absorption is too weak to explain the asymmetry. It is suggested that the absorption occurs in a cool turbulent region between the base of the circumstellar shell and the top of the chromosphere

    Els alumnes de segon grau de formació professional fan pràctiques a les empreses

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    Can pollen provision mitigate competition interactions between three phytoseiid predators of Tetranychus urticae under future climate change conditions?

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    Biological control can be severely disrupted by hot and dry environmental conditions associated with climate change. These conditions may alter the food web configuration of arthropod communities through their effects on species interactions. They could disrupt the competition between the phytoseiid predators Euseius stipulatus, Neoseiulus californicus, and Phytoseiulus persimilis, which are the key natural enemies of Tetranychus urticae in citrus in Spain. Because the provision of alternative food could compensate for such a situation, we studied in laboratory conditions whether pollen supply could modify competition among these predatory species under different climatic conditions. Our results show that access to high-quality pollen may enhance the performance of E. stipulatus and N. californicus. However, when the phytoseiids considered in our study were forced to compete, pollen provision had contrasting effects depending on the competing pair. Overall, climate change did not affect predation when pollen was available. Predation, though, was lower than expected except when the competing pair was P. persimilis and E. stipulatus. Therefore, pollen provision can partially mitigate the adverse effects of climate change on some of the biological parameters of the three main predators of T. urticae when competing in the system. This has important implications for the future success of biological pest control.Funding for open access charge: CRUE-Universitat Jaume IThe authors thank M. Piquer (UJI) and Arcadi Sanz (UJI) for technical assistance, J. Calvo (KOPPERT BS, Spain) for supplying N. californicus, M.V Ibáñez-Gual (UJI) for statistical advice, and C. Rodriguez-Saona for comments on an earlier version of the manuscript. PUB received a predoctoral grant from MCINN (EEBB-I-14-08555)

    Switcher-random-walks: a cognitive-inspired mechanism for network exploration

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    Semantic memory is the subsystem of human memory that stores knowledge of concepts or meanings, as opposed to life specific experiences. The organization of concepts within semantic memory can be understood as a semantic network, where the concepts (nodes) are associated (linked) to others depending on perceptions, similarities, etc. Lexical access is the complementary part of this system and allows the retrieval of such organized knowledge. While conceptual information is stored under certain underlying organization (and thus gives rise to a specific topology), it is crucial to have an accurate access to any of the information units, e.g. the concepts, for efficiently retrieving semantic information for real-time needings. An example of an information retrieval process occurs in verbal fluency tasks, and it is known to involve two different mechanisms: -clustering-, or generating words within a subcategory, and, when a subcategory is exhausted, -switching- to a new subcategory. We extended this approach to random-walking on a network (clustering) in combination to jumping (switching) to any node with certain probability and derived its analytical expression based on Markov chains. Results show that this dual mechanism contributes to optimize the exploration of different network models in terms of the mean first passage time. Additionally, this cognitive inspired dual mechanism opens a new framework to better understand and evaluate exploration, propagation and transport phenomena in other complex systems where switching-like phenomena are feasible.Comment: 9 pages, 3 figures. Accepted in "International Journal of Bifurcations and Chaos": Special issue on "Modelling and Computation on Complex Networks

    Results of the meteorological model WRF-ARW over Catalonia, using different parameterizations of convection and cloud microphysics

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    The meteorological model WRF-ARW (Weather Research and Forecasting - Advanced ResearchWRF) is a new generation model that has a worldwide growing community of users. In theframework of a project that studies the feasibility of implementing it operationally at the Mete-orological Service of Catalonia, a verification of the forecasts produced by the model in severalcases of precipitation observed over Catalonia has been carried out. Indeed, given the impor-tance of precipitation forecasts in this area, one of the main objectives was to study the sensitivityof the model in different configurations of its parameterizations of convection and cloud micro-physics. In this paper, we present the results of this verification for two domains, a 36-km gridsize and one of 12 km grid size, unidirectionally nested to the previous one. In the externaldomain, the evaluation was based on the analysis of the main statistical parameters (ME andRMSE) for temperature, relative humidity, geopotential and wind, and it has been determinedthat the combination using the Kain-Fritsch convective scheme with the WSM5 microphysicalscheme has provided the best results. Then, with this configuration set for the external domain,some forecasts at the nested domain have been done, by combining different convection andcloud microphysics schemes, leading to the conclusion that the most accurate configuration isthe one combining the convective parameterization of Kain-Fritsch and the Thompson micro-physics scheme

    The moderating effects of mindful eating on the relationship between emotional functioning and eating styles in overweight and obese women

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    The aim of the current study was to examine the moderating effect of mindful eating on the relationship between emotional functioning and eating styles in overweight and obese women. One hundred and eighty four overweight and obese adult women (BMI 30.12\u2009\ub1\u20093.77 kg/m2) were assessed with the Difficulties in Emotion Regulation Scale, the Positive and Negative Affect Schedule, the Three Factor Eating Questionnaire and the Mindful Eating Scale. Mindful eating significantly moderated several of the relationships between emotional functioning and eating styles. When mindful eating techniques are included as part of an intervention for overweight or obese individuals, it is even more important that those interventions should also include techniques to reduce emotion dysregulation and negative affect

    The irreducible unitary representations of the extended Poincare group in (1+1) dimensions

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    We prove that the extended Poincare group in (1+1) dimensions is non-nilpotent solvable exponential, and therefore that it belongs to type I. We determine its first and second cohomology groups in order to work out a classification of the two-dimensional relativistic elementary systems. Moreover, all irreducible unitary representations of the extended Poincare group are constructed by the orbit method. The most physically interesting class of irreducible representations corresponds to the anomaly-free relativistic particle in (1+1) dimensions, which cannot be fully quantized. However, we show that the corresponding coadjoint orbit of the extended Poincare group determines a covariant maximal polynomial quantization by unbounded operators, which is enough to ensure that the associated quantum dynamical problem can be consistently solved, thus providing a physical interpretation for this particular class of representations.Comment: 12 pages, Revtex 4, letter paper; Revised version of paper published in J. Math. Phys. 45, 1156 (2004
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