550 research outputs found

    Timing of detachment faulting in the Bullfrog Hills and Bare Mountain area, southwest Nevada: Inferences from 40Ar/39Ar, K-Ar, U-Pb and fission track thermochronology

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    Crustal extension in the Bullfrog Hills and Bare Mountain area of southwest Nevada is associated with movement along a regional detachment fault. Normal faulting in the upper plate and rapid cooling (denudation) of the lower plate were coeval with Miocene silicic volcanism and with west-northwest transport along the detachment fault. A west-northwest progression of tilting along upper plate normal faults is indicated by ages of the volcanic rocks in relation to angular unconformities. Near the breakaway, tilting in the upper plate occurred between 12.7 and 11.6 Ma, continued less strongly past 10.7 Ma, and was over by 8.2 Ma. Ten to 20 km west of the breakaway, tilting occurred between 10.7 and 10.33 Ma, continued less strongly after 10.33 Ma, and was over by 8.1 Ma. The cooling histories of the lower plate metamorphic rocks were determined by thermochronologic dating methods: K-Ar and Ar-40/(39)A on muscovite, biotite, and hornblende, Ar-40/(39)A on K-feldspar, U-Pb on apatite, zircon, and sphene, and fission track on apatite, zircon, and sphene. Lower plate rocks 10 km west of the breakaway cooled slowly from Early Cretaceous lower-amphibolite facies conditions through 350+/-50 degrees to 300+/-50 degrees C between 57 and 38 Ma, then cooled rapidly from 205+/-50 degrees to 120+/-5O degrees C between 12.6+/-1.6 and 11.1+/-1.9 Ma. Lower plate rocks 20 km west of the breakaway cooled slowly from Early Cretaceous upper-amphibolite facies conditions through 500+/-50 degrees C at 78-67 Ma, passed through 350+/-50 degrees to 300+/-50 degrees C between 16.3+/-0.4 and 10.5+/-0.3 Ma, then cooled rapidly from 285+/-50 degrees to 120+/-50 degrees C between 10.2 and 8.6 Ma. Upper plate tilting and rapid cooling (denudation) of the lower plate occurred simultaneously in the respective areas. The early slow-cooling part of the lower plate thermal histories was probably related to erosion at the Earth's surface, which stripped off about 9 km of material in 50 to 100 m.y. The results indicate an initial fault dip greater than or equal to 30 degrees and a 12 mm yr(-1) west-northwest migration of the locus of rapid tilting in the upper plate

    The ANTARES Optical Beacon System

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    ANTARES is a neutrino telescope being deployed in the Mediterranean Sea. It consists of a three dimensional array of photomultiplier tubes that can detect the Cherenkov light induced by charged particles produced in the interactions of neutrinos with the surrounding medium. High angular resolution can be achieved, in particular when a muon is produced, provided that the Cherenkov photons are detected with sufficient timing precision. Considerations of the intrinsic time uncertainties stemming from the transit time spread in the photomultiplier tubes and the mechanism of transmission of light in sea water lead to the conclusion that a relative time accuracy of the order of 0.5 ns is desirable. Accordingly, different time calibration systems have been developed for the ANTARES telescope. In this article, a system based on Optical Beacons, a set of external and well-controlled pulsed light sources located throughout the detector, is described. This calibration system takes into account the optical properties of sea water, which is used as the detection volume of the ANTARES telescope. The design, tests, construction and first results of the two types of beacons, LED and laser-based, are presented.Comment: 21 pages, 18 figures, submitted to Nucl. Instr. and Meth. Phys. Res.

    Western men and Eastern arts: The significance of Eastern martial arts disciplines in British men's narratives of masculinity

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    Previous Western sociological research on Eastern martial arts has identified a tension between ‘traditional’ Eastern forms of practice and ‘modernized’ Western methods of training and competition. In particular, the ‘sportization’ of Eastern styles, where combat-centred arts based upon moral philosophies have transformed more or less into competitive activities following Western models of rationalized sport, has been an important theme. However, it is also suggested that Eastern martial arts hold special significance in the West for their seemingly esoteric nature. In this regard, such martial arts are considered significant because they are not ‘sports’, but rather disciplines, with fairly different connotations for practitioners. Drawing on interview data, this paper explores how Western practitioners of Eastern martial arts articulate this difference, principally by examining the place of martial artistry in British men's narratives of masculinity. Comparing themselves favourably to assumed, typical visions of Western sporting masculinity, such men draw upon the imagined uniqueness of their martial arts to construct a sense of moral superiority over other men. In so doing, they contribute to a rejection of what they believe to be ‘mainstream’ sporting Western masculinity, thus indicating the role that ‘alternative’ visions of physical culture can play in men's active constructions of gender

    Foundations of Black Hole Accretion Disk Theory

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    This review covers the main aspects of black hole accretion disk theory. We begin with the view that one of the main goals of the theory is to better understand the nature of black holes themselves. In this light we discuss how accretion disks might reveal some of the unique signatures of strong gravity: the event horizon, the innermost stable circular orbit, and the ergosphere. We then review, from a first-principles perspective, the physical processes at play in accretion disks. This leads us to the four primary accretion disk models that we review: Polish doughnuts (thick disks), Shakura-Sunyaev (thin) disks, slim disks, and advection-dominated accretion flows (ADAFs). After presenting the models we discuss issues of stability, oscillations, and jets. Following our review of the analytic work, we take a parallel approach in reviewing numerical studies of black hole accretion disks. We finish with a few select applications that highlight particular astrophysical applications: measurements of black hole mass and spin, black hole vs. neutron star accretion disks, black hole accretion disk spectral states, and quasi-periodic oscillations (QPOs).Comment: 91 pages, 23 figures, final published version available at http://www.livingreviews.org/lrr-2013-

    A theoretical model of inflammation- and mechanotransduction- driven asthmatic airway remodelling

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    Inflammation, airway hyper-responsiveness and airway remodelling are well-established hallmarks of asthma, but their inter-relationships remain elusive. In order to obtain a better understanding of their inter-dependence, we develop a mechanochemical morphoelastic model of the airway wall accounting for local volume changes in airway smooth muscle (ASM) and extracellular matrix in response to transient inflammatory or contractile agonist challenges. We use constrained mixture theory, together with a multiplicative decomposition of growth from the elastic deformation, to model the airway wall as a nonlinear fibre-reinforced elastic cylinder. Local contractile agonist drives ASM cell contraction, generating mechanical stresses in the tissue that drive further release of mitogenic mediators and contractile agonists via underlying mechanotransductive signalling pathways. Our model predictions are consistent with previously described inflammation-induced remodelling within an axisymmetric airway geometry. Additionally, our simulations reveal novel mechanotransductive feedback by which hyper-responsive airways exhibit increased remodelling, for example, via stress-induced release of pro-mitogenic and procontractile cytokines. Simulation results also reveal emergence of a persistent contractile tone observed in asthmatics, via either a pathological mechanotransductive feedback loop, a failure to clear agonists from the tissue, or a combination of both. Furthermore, we identify various parameter combinations that may contribute to the existence of different asthma phenotypes, and we illustrate a combination of factors which may predispose severe asthmatics to fatal bronchospasms

    Modelling of the effect of ELMs on fuel retention at the bulk W divertor of JET

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    Effect of ELMs on fuel retention at the bulk W target of JET ITER-Like Wall was studied with multi-scale calculations. Plasma input parameters were taken from ELMy H-mode plasma experiment. The energetic intra-ELM fuel particles get implanted and create near-surface defects up to depths of few tens of nm, which act as the main fuel trapping sites during ELMs. Clustering of implantation-induced vacancies were found to take place. The incoming flux of inter-ELM plasma particles increases the different filling levels of trapped fuel in defects. The temperature increase of the W target during the pulse increases the fuel detrapping rate. The inter-ELM fuel particle flux refills the partially emptied trapping sites and fills new sites. This leads to a competing effect on the retention and release rates of the implanted particles. At high temperatures the main retention appeared in larger vacancy clusters due to increased clustering rate

    EFSA NDA Panel (EFSA Panel on Dietetic Products, Nutrition and Allergies), 2013. Scientific Opinion on Dietary Reference Values for vitamin C

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    Experiences of expressing and storing colostrum antenatally: A qualitative study of mothers in regional Western Australia

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    This qualitative study explored the experiences and breastfeeding outcomes of a group of mothers who expressed colostrum in the antenatal period. In-depth interviews were conducted over the telephone with 12 women who had attended a unique antenatal lactation clinic appointment at 37 weeks’ gestation. Seven main response themes were identified. Most women reflected positively upon their attendance and reported that the experience of expressing colostrum allowed them to become familiar with their breasts and gave them a sense of security by having a supply of colostrum stored for possible use after birth. The main negative emotions reported were a sense of embarrassment at expressing the colostrum, particularly in front of another person, the difficulties with expressing colostrum and in one instance, the physical pain associated with the process. Antenatal expression of colostrum may improve maternal breastfeeding confidence. Further research using long-term records will determine whether this practice improves breastfeeding outcomes

    Young carers in England: Findings from the 2018 BBC survey on the prevalence and nature of caring among young people

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    Background. Many young people are involved in caring for parents, siblings, or other relatives who have an illness or disability. The aim of this study was to estimate the prevalence of caring by young people in England.Method. A national survey of 925 English young people was conducted using the 18-item survey version of the Multidimensional Assessment of Caring Activities Checklist for Young Carers (MACA-YC18).Results. Around 7% of young people were identified as doing a high amount of caring activity, and 3% a very high amount. Most frequently, caring by a young person is for a mother or a sibling, with a physical disability. Caring activity consisted mostly of domesticactivities, household management, and emotional care.Conclusion. This study provides the most up to date and methodologically sophisticated survey data on the prevalence of young caring in England, with implications for policy and practice
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