7,672 research outputs found

    The SKA view of the Neutral Interstellar Medium in Galaxies

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    Two major questions in galaxy evolution are how star-formation on small scales leads to global scaling laws and how galaxies acquire sufficient gas to sustain their star formation rates. HI observations with high angular resolution and with sensitivity to very low column densities are some of the important observational ingredients that are currently still missing. Answers to these questions are necessary for a correct interpretation of observations of galaxy evolution in the high-redshift universe and will provide crucial input for the sub-grid physics in hydrodynamical simulations of galaxy evolutions. In this chapter we discuss the progress that will be made with the SKA using targeted observations of nearby individual disk and dwarf galaxies.Comment: 22 pages, 4 figures, to appear as part of 'Neutral Hydrogen' in Proceedings 'Advancing Astrophysics with the SKA (AASKA14)', PoS(AASKA14)12

    Expected Large Synoptic Survey Telescope (LSST) Yield of Eclipsing Binary Stars

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    In this paper we estimate the Large Synoptic Survey Telescope (LSST) yield of eclipsing binary stars, which will survey ~20,000 square degrees of the southern sky during the period of 10 years in 6 photometric passbands to r ~ 24.5. We generate a set of 10,000 eclipsing binary light curves sampled to the LSST time cadence across the whole sky, with added noise as a function of apparent magnitude. This set is passed to the Analysis of Variance (AoV) period finder to assess the recoverability rate for the periods, and the successfully phased light curves are passed to the artificial intelligence-based pipeline EBAI to assess the recoverability rate in terms of the eclipsing binaries' physical and geometric parameters. We find that, out of ~24 million eclipsing binaries observed by LSST with S/N>10 in mission life-time, ~28% or 6.7 million can be fully characterized by the pipeline. Of those, ~25% or 1.7 million will be double-lined binaries, a true treasure trove for stellar astrophysics.Comment: 19 pages, 7 figures. Accepted to AJ, to appear in issue 142:2 (Aug 2011

    Depairing critical current achieved in superconducting thin films with through-thickness arrays of artificial pinning centers

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    Large area arrays of through-thickness nanoscale pores have been milled into superconducting Nb thin films via a process utilizing anodized aluminum oxide thin film templates. These pores act as artificial flux pinning centers, increasing the superconducting critical current, Jc, of the Nb films. By optimizing the process conditions including anodization time, pore size and milling time, Jc values approaching and in some cases matching the Ginzburg-Landau depairing current of 30 MA/cm^2 at 5 K have been achieved - a Jc enhancement over as-deposited films of more than 50 times. In the field dependence of Jc, a matching field corresponding to the areal pore density has also been clearly observed. The effect of back-filling the pores with magnetic material has then been investigated. While back-filling with Co has been successfully achieved, the effect of the magnetic material on Jc has been found to be largely detrimental compared to voids, although a distinct influence of the magnetic material in producing a hysteretic Jc versus applied field behavior has been observed. This behavior has been tested for compatibility with currently proposed models of magnetic pinning and found to be most closely explained by a model describing the magnetic attraction between the flux vortices and the magnetic inclusions.Comment: 9 pages, 10 figure

    Prevalence of Mental Health Disorder Symptoms and Rates of Help-seeking Among University-Enrolled, Black Men

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    Background. Black men in college represent a subgroup of emerging adults who are at increased risk of developing mental health disorders (MHDs), such as anxiety and depression. Such risk has been attributed to disproportionate experiences with everyday racial discrimination and high levels of psychological distress. Despite being at higher risk, university-enrolled, Black men are not utilizing mental health or health resources at optimal rates. The current evidence base describing prevalence of MHDs and health services utilization among Black men in college is limited. The present study addresses this by examining mental health prevalence among university-enrolled, Black men and their rates of health services utilization. Methods. We analyzed data (N ~ 2500) from a student survey, Spit for Science, a longitudinal, ongoing, research study at a mid-Atlantic, public university. Participants are given surveys in their freshman year and follow-up surveys every spring thereafter. Measures included: mental health disorders (depression and anxiety, as measured by the Symptom Checklist 90) and campus health service utilization (counseling center, health services, wellness center, and recreational sports). We conducted descriptive analyses to determine MHD symptom prevalence and utilization rates; Mann Whitney U tests to compare prevalence rates to White men and Black women; and, Chi-squared tests to compare rates of utilization among groups. Results. During their Freshman year, greater than 60% of students from each ethnic group reported at least one anxiety symptom and greater than 80% reported at least one depressive symptom. By senior year, reporting rates decreased significantly for Black men (49.6%) but remained high for White men (69.1%) and Black women (63%); p \u3c0.000. For depression, results were similar; however, only significant differences between Black men (72.7%) and Black women (87.1%); p\u3c0.000. Black men (20.4%), though reporting high levels of symptoms, still utilized counseling services at lower rates compared to White men (37.76%); p = 0.024. Conclusion. Findings suggest that Black men underutilize available campus health resources despite reporting one or more symptoms associated with anxiety and depression. Further research and prevention efforts are needed to improve help-seeking among this vulnerable population.https://scholarscompass.vcu.edu/gradposters/1077/thumbnail.jp

    The validity of the Spelling and Grammar Waiver as a reasonable accommodation in Leaving Certificate examinations in Ireland

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    In Ireland, dyslexic students can apply for reasonable accommodations in Leaving Certificate examinations. One such accommodation is the Spelling and Grammar Waiver (SGW). Questions have been raised regarding its validity, and it has been suggested that it gives an unfair advantage. Mock Leaving Certificate English paper scripts were collected from 31 dyslexic students who had been granted an SGW and 31 nondyslexic students who had not been granted any accommodations. All scripts were marked twice, eight weeks apart, by the same marker, once in the standard fashion and once with an SGW. Dyslexic students’ scripts marked with an SGW had a significantly higher mean score than when marked in the standard way, and it was similar to the mean unaccommodated score of nondyslexic students. However, nondyslexic students also received a similar boost in scores when accommodated. Two-way repeated measures ANOVA showed no “differential boost” for the dyslexic group, but a significant boost for both groups when accommodated. Results suggest that the SGW is not a valid accommodation but confers an advantage to those that have it. This study needs replication using larger numbers, with real Leaving Certificate scripts and examiners, and the reasons for the increase in scores also need investigation

    Observation and implications of the Epeak - Eiso correlation in Gamma-Ray Bursts

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    The availability of a few dozen GRB redshifts now allows studies of the intrinsic properties of these high energy transients. Amati et al. recently discovered a correlation between Epeak, the intrinsic peak energy of the νfν\nu f \nu spectrum, and Eiso, the isotropic equivalent energy radiated by the source. Lamb et al. have shown that HETE-2 data confirm and extend this correlation. We discuss here one of the consequences of this correlation: the existence of a 'spectral standard candle', which can be used to construct a simple redshift indicator for GRBs.Comment: Proceedings of the GRB 2003 Conference in SantaFe, 5 pages, 4 figure

    The School Sport Co-ordinator Programme: Changing the Role of the Physical Education Teacher?

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    Over the last decade or so, young people have increasingly become a focus of UK sport policy. Fuelled in part by concerns such as the increasing levels of childhood inactivity and obesity, and the lack of international success in sport, a plethora of policy initiatives aimed at young people have been developed. In April 2000, the government published its sport strategy document, A Sporting Future for All, pulling together all the threads of recent policies, and in it, restating its commitment to youth sport, sport in education, excellence and sport in the community. One such policy initiative, the School Sport Co-ordinator programme, is the focus of this paper. The School Sport Co-ordinator programme, currently being introduced into schools in England, is an initiative that involves two government departments (sport and education) and a number of other agencies, reflecting the government's current agenda to ensure 'joined up policy' thinking. It aims to develop opportunities for youth sport through co-ordinated links between PE and sport in schools, both within and outside of the formal curriculum, with those in local community sports settings. The essence of the School Sport Co-ordinator programme is to free up nominated teachers in schools from teaching to allow them time for development activities, specifically to encourage schools and community sports providers to work in partnership. This paper draws on data from an ongoing research project examining the implementation of one School Sport Co-ordinator partnership, 'northbridge'. Drawing on in-depth interviews, it explores the perceptions of the newly established School Sport Co-ordinators of their changing role. The paper highlights some of the initial tensions and challenges for them in their task of working across different educational and sporting contexts

    Blaming the victim, all over again: Waddell and Aylward's biopsychosocial (BPS) model of disability

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    The biopsychosocial (BPS) model of mental distress, originally conceived by the American psychiatrist George Engel in the 1970s and commonly used in psychiatry and psychology, has been adapted by Gordon Waddell and Mansell Aylward to form the theoretical basis for current UK Government thinking on disability. Most importantly, the Waddell and Aylward version of the BPS has played a key role as the Government has sought to reform spending on out-of- work disability benefits. This paper presents a critique of Waddell and Aylward’s model, examining its origins, its claims and the evidence it employs. We will argue that its potential for genuine inter-disciplinary cooperation and the holistic and humanistic benefits for disabled people as envisaged by Engel are not now, if they ever have been, fully realized. Any potential benefit it may have offered has been eclipsed by its role in Coalition/Conservative government social welfare policies that have blamed the victim and justified restriction of entitlements

    Mid-infrared spectra of late-type stars: Long-term evolution

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    Recent ground-based mid-infrared spectra of 29 late-type stars, most with substantial dust shells, are compared to ground-based spectra of these stars from the 1960s and 1970s and to IRAS-LRS spectra obtained in 1983. The spectra of about half the stars show no detectable changes, implying that their distributions of circumstellar material and associated dust grain properties have changed little over this time interval. However, many of the stars with strong silicate features showed marked changes. In nearly all cases the silicate peak has strengthened with respect to the underlying continuum, although there is one case (VY~CMa) in which the silicate feature has almost completely disappeared. This suggests that, in general, an oxygen-rich star experiences long periods of gradual silicate feature strengthening, punctuated by relatively rare periods when the feature weakens. We discuss various mechanisms for producing the changes, favoring the slow evolution of the intrinsic dust properties (i.e., the chemical composition or grain structure). Although most IRAS spectra agree well with ground-based spectra, there are a number of cases where they fall well outside the expected range of uncertainty. In almost all such cases the slopes of the red and blue LRS spectra do not match in their region of overlap.Comment: Accepted in ApJ, 20 pages, 5 figures, 1 tabl
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