8,265 research outputs found

    Muon Detection of TeV Gamma Rays from Gamma Ray Bursts

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    Because of the limited size of the satellite-borne instruments, it has not been possible to observe the flux of gamma ray bursts (GRB) beyond GeV energy. We here show that it is possible to detect the GRB radiation of TeV energy and above, by detecting the muon secondaries produced when the gamma rays shower in the Earth's atmosphere. Observation is made possible by the recent commissioning of underground detectors (AMANDA, the Lake Baikal detector and MILAGRO) which combine a low muon threshold of a few hundred GeV or less, with a large effective area of 10^3 m^2 or more. Observations will not only provide new insights in the origin and characteristics of GRB, they also provide quantitative information on the diffuse infrared background.Comment: Revtex, 12 pages, 3 postscript figures, uses epsfig.st

    Development and psychometric assessment of the basic resuscitation skills self-efficacy scale

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    Background: Nurses are usually the first responders to an in-hospital cardiac arrest. As bystanders, nurses are expected to master some basic resuscitation skills. Self-efficacy levels are a key component in the acquisition of basic resuscitation skills. Aim: To develop, test and validate a self-efficacy scale that accurately measures nursing students’ confidence levels in their capabilities when responding to a cardiac arrest. Methods: This study enrolled a conveniently recruited sample of 768 nursing students from two different universities in Europe. The Basic Resuscitation Skills Self-Efficacy Scale (BRS-SES) was developed and its psychometrics established. Content validity, criterion validity, discriminant validity, and internal consistency were assessed. Performing item-analysis, principal component analysis and known group analysis evaluated construct validity. Results: Principal component analysis revealed the three-subscale structure of the final 18-item BRS-SES. A Cronbach’s alpha of 0.96 for the overall measure demonstrated the internal consistency of the BRS-SES. Data also evidenced discriminant ability of the BRS-SES and known-group analysis showed its high sensitivity and specificity. Conclusion: The BRS-SES showed good psychometric properties for measuring self-efficacy in basic resuscitation skills that nursing students, as future first responders to an in-hospital cardiac arrest, will be expected to master. Implications for practice: The BRS-SES is a validated tool that could have a positive impact on the training of basic resuscitation skills and, therefore, on patients’ outcomes

    Estudio biométrico de la abeja melífera (Apis mellifera, Linneo 1758) (Hymenoptera, Apidae) de la isla de La Palma del Archipiélago Canario. II. Ángulos y longitudes de las alas.

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    The honey bees (A. mellifera L.) from the island of La Palma constitute a morphological group within which differences related to the geographical location of the apiaries are difficult to distinguish, probably due to the buying and selling of hives among beekeepers, and also to the migratory style of bee-keeping practised on the island. We have also studied the possible relationship of these bees with A. m. intermissa, which is distributed throughout the north of Africa, and with A. m. iberica in the Iberian Peninsula. Our results indicate that these bees are probably the result of a cross between these two races followed by selection of the best genotypes adapted to the environmental conditions.Las abejas meliferas (A. mellifera L.) oriundas de la isla de La Palma constituyen un grupo morfológico, en el que no podemos apreciar diferencias relacionadas con la localización geográfica de los colmenares; probablemente esto sea debido a las prácticas de compra-venta de colmenas entre los apicultores, y a la transhumancia practicada dentro de la isla. También hemos estudiado la posible relación de parentesco de estas abejas con la raza que se distribuye por el norte de África (A. m. intermissa), o con la que se localiza en la Península Ibérica (A. m. iberica). Los resultados obtenidos nos indican que probablemente estos animales sean el resultado de un proceso cruce entre las dos razas, y posterior selección de los genotipos mejor adaptados a unas determinadas condiciones ambientales

    Evolvability meets biogeography: evolutionary potential decreases at high and low environmental favourability

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    This is the author accepted manuscript. The final version is available from the Royal Society via the DOI in this record.Understanding and forecasting the effects of environmental change on wild populations requires knowledge on a critical question: Do populations have the ability to evolve in response to that change? However, our knowledge on how evolution works in wild conditions under different environmental circumstances is extremely limited. We investigated how environmental variation influences the evolutionary potential of phenotypic traits. We used published data to collect or calculate 135 estimates of evolvability of morphological traits of European wild bird populations. We characterised the environmental favourability of each population throughout the species’ breeding distribution. Our results suggest that the evolutionary potential of morphological traits decreases as environmental favourability becomes high or low. Strong environmental selection pressures and high intra-specific competition may reduce species’ evolutionary potential in low and high favourability areas, respectively. This suggests that species may be least able to adapt to new climate conditions at their range margins and at the centre. Our results underscore the need to consider the evolutionary potential of populations when studying the drivers of species distributions, particularly when predicting the effects of environmental change. We discuss the utility of integrating evolutionary dynamics into a biogeographical perspective to understand how environmental variation shapes evolutionary patterns. This approach would also produce more reliable predictions about the effect of environmental change on population persistence and therefore on biodiversity.We acknowledge funding from the Spanish Ministerio de Economía y Competitividad (grants CGL2012-34685, CGL2015-70639-P, and CGL2016-76173-P) and thanks to the ERA-Net BiodivERsA, with the national funder FCT (Project: BIODIVERSA/0003/2011). AE has a contract funded by the project 1098/2014 (Organismo Autónomo Parques Nacionales, Spain)

    Langevin dynamics of the Lebowitz-Percus model

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    We revisit the hard-spheres lattice gas model in the spherical approximation proposed by Lebowitz and Percus (J. L. Lebowitz, J. K. Percus, Phys. Rev.{\ 144} (1966) 251). Although no disorder is present in the model, we find that the short-range dynamical restrictions in the model induce glassy behavior. We examine the off-equilibrium Langevin dynamics of this model and study the relaxation of the density as well as the correlation, response and overlap two-time functions. We find that the relaxation proceeds in two steps as well as absence of anomaly in the response function. By studying the violation of the fluctuation-dissipation ratio we conclude that the glassy scenario of this model corresponds to the dynamics of domain growth in phase ordering kinetics.Comment: 21 pages, RevTeX, 14 PS figure
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