2,815 research outputs found

    Theory of winds in late-type evolved and pre-main-sequence stars

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    Recent observational results confirm that many of the physical processes which are known to occur in the Sun also occur among late-type stars in general. One such process is the continuous loss of mass from a star in the form of a wind. There now exists an abundance of either direct or circumstantial evidence which suggests that most (if not all) stars in the cool portion of the HR diagram possess winds. An attempt is made to assess the current state of theoretical understanding of mass loss from two distinctly different classes of late-type stars: the post-main-sequence giant/supergiant stars and the pre-main-sequence T Tauri stars. Toward this end, the observationally inferred properties of the wind associated with each of the two stellar classes under consideration are summarized and compared against the predictions of existing theoretical models. Although considerable progress has been made in attempting to identify the mechanisms responsible for mass loss from cool stars, many fundamental problems remain to be solved

    The risk matrix : drug-related deaths in prisons in England and Wales, 2015-2020

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    Aims: This article explores the factors contributing to drug-related deaths in English and Welsh prisons between 2015-2020. Methods: Based on content analysis of all Prison and Probation Ombudsman ‘other non-natural’ fatal incident investigation reports, descriptive statistics were generated. Qualitative analysis explored the circumstances surrounding deaths and key risk factors. Results: Most deaths were of men, whose mean age was 39 years. Drug toxicity was a main factor in causing death, exacerbated by underlying physical health conditions and risk-taking behaviours. A variety of substances were involved. New psychoactive substances became more important over time. A high proportion had recorded histories of substance use and mental illness. During this period, the prison system was under considerable stress creating dangerous environments for drug-related harm. Conclusion: This study highlights the process of complex interaction between substances used, individual characteristics, situational features and the wider environment in explaining drug-related deaths in prisons. Implications for policy and practice are discussed

    Infrequent small bowel intestinal bacterial overgrowth in malnourished Zambian children.

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    There is evidence that children with malnutrition have an increased frequency of small intestinal bacterial overgrowth (SIBO) due to impaired gastric acidity, impaired intestinal motility, and dysbiosis. Children with malnutrition respond to antibiotic therapy but it is not clear if this effect is mediated by treatment of SIBO. We set out to determine the frequency of SIBO in children of varying nutritional status in a poor community in Lusaka, Zambia. Hydrogen breath testing, following a dose of 1g/kg oral glucose, was used to determine the presence of SIBO amongst the study participants. Forty nine children, 45 of whom had varying degrees of malnutrition, completed a full series of observations at 15, 30 and 60 minutes. Four children (8%) had a rise of 10ppm from baseline, consistent with SIBO. No correlation with nutritional status was observed. In this small study of Zambian children, SIBO was infrequent and unrelated to nutritional status

    Mode identification in rapidly rotating stars

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    Context: Recent calculations of pulsation modes in rapidly rotating polytropic models and models based on the Self-Consistent Field method have shown that the frequency spectrum of low degree pulsation modes can be described by an empirical formula similar to Tassoul's asymptotic formula, provided that the underlying rotation profile is not too differential. Aims: Given the simplicity of this asymptotic formula, we investigate whether it can provide a means by which to identify pulsation modes in rapidly rotating stars. Methods: We develop a new mode identification scheme which consists in scanning a multidimensional parameter space for the formula coefficients which yield the best-fitting asymptotic spectra. This mode identification scheme is then tested on artificial spectra based on the asymptotic formula, on random frequencies and on spectra based on full numerical eigenmode calculations for which the mode identification is known beforehand. We also investigate the effects of adding random frequencies to mimic the effects of chaotic modes which are also expected to show up in such stars. Results: In the absence of chaotic modes, it is possible to accurately find a correct mode identification for most of the observed frequencies provided these frequencies are sufficiently close to their asymptotic values. The addition of random frequencies can very quickly become problematic and hinder correct mode identification. Modifying the mode identification scheme to reject the worst fitting modes can bring some improvement but the results still remain poorer than in the case without chaotic modes

    Technical Design Report for PANDA Electromagnetic Calorimeter (EMC)

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    This document presents the technical layout and the envisaged performance of the Electromagnetic Calorimeter (EMC) for the PANDA target spectrometer. The EMC has been designed to meet the physics goals of the PANDA experiment. The performance figures are based on extensive prototype tests and radiation hardness studies. The document shows that the EMC is ready for construction up to the front-end electronics interface

    Predicting total reaction cross sections for nucleon-nucleus scattering

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    Nucleon total reaction and neutron total cross sections to 300 MeV for 12C and 208Pb, and for 65 MeV spanning the mass range, are predicted using coordinate space optical potentials formed by full folding of effective nucleon-nucleon interactions with realistic nuclear ground state densities. Good to excellent agreement is found with existing data.Comment: 10 pages, 4 figure

    Consequences of sexual harassment in sport for female athletes

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    Sexual harassment research was first undertaken in the workplace and educational settings. Research on sexual harassment in sport is scarce but has grown steadily since the mid-1980s. Even so, very little is known about the causes and/or characteristics and/or consequences of sexual harassment in sport settings. This article reports on the findings from interviews with 25 elite female athletes in Norway who indicated in a prior survey (N =572) that they had experienced sexual harassment from someone in sport. The consequences of the incidents of sexual harassment that were reported were mostly negative, but some also reported that their experiences of sexual harassment had had no consequences for them. “Thinking about the incidents”, a “destroyed relationship to the coach”, and “more negative view of men in general” were the most often negative consequences mentioned. In addition, a surprising number had chosen to move to a different sport or to drop out of elite sport altogether because of the harassment

    Technical Design Report for the PANDA Micro Vertex Detector

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    This document illustrates the technical layout and the expected performance of the Micro Vertex Detector (MVD) of the PANDA experiment. The MVD will detect charged particles as close as possible to the interaction zone. Design criteria and the optimisation process as well as the technical solutions chosen are discussed and the results of this process are subjected to extensive Monte Carlo physics studies. The route towards realisation of the detector is outlined

    Pulsation modes in rapidly rotating stellar models based on the Self-Consistent Field method

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    Context: New observational means such as the space missions CoRoT and Kepler and ground-based networks are and will be collecting stellar pulsation data with unprecedented accuracy. A significant fraction of the stars in which pulsations are observed are rotating rapidly. Aims: Our aim is to characterise pulsation modes in rapidly rotating stellar models so as to be able to interpret asteroseismic data from such stars. Methods: The pulsation code developed in Ligni\`eres et al. (2006) and Reese et al. (2006) is applied to stellar models based on the self-consistent field (SCF) method (Jackson et al. 2004, 2005, MacGregor et al. 2007). Results: Pulsation modes in SCF models follow a similar behaviour to those in uniformly rotating polytropic models, provided that the rotation profile is not too differential. Pulsation modes fall into different categories, the three main ones being island, chaotic, and whispering gallery modes, which are rotating counterparts to modes with low, medium, and high l-|m| values, respectively. The frequencies of the island modes follow an asymptotic pattern quite similar to what was found for polytropic models. Extending this asymptotic formula to higher azimuthal orders reveals more subtle behaviour as a function of m and provides a first estimate of the average advection of pulsation modes by rotation. Further calculations based on a variational principle confirm this estimate and provide rotation kernels that could be used in inversion methods. When the rotation profile becomes highly differential, it becomes more and more difficult to find island and whispering gallery modes at low azimuthal orders. At high azimuthal orders, whispering gallery modes, and in some cases island modes, reappear.Comment: 16 pages, 11 figures, accepted for publication in A&
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