1,325 research outputs found

    Neutrino flavor mixing with moments

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    The successful transition from core-collapse supernova simulations using classical neutrino transport to simulations using quantum neutrino transport will require the development of methods for calculating neutrino flavor transformations that mitigate the computational expense. One potential approach is the use of angular moments of the neutrino field, which has the added appeal that there already exist simulation codes which make use of moments for classical neutrino transport. Evolution equations for quantum moments based on the quantum kinetic equations can be straightforwardly generalized from the evolution of classical moments based on the Boltzmann equation. We present an efficient implementation of neutrino transformation using quantum angular moments in the free streaming, spherically symmetric bulb model. We compare the results against analytic solutions and the results from more exact multi-angle neutrino flavor evolution calculations. We find that our moment-based methods employing scalar closures predict, with good accuracy, the onset of collective flavor transformations seen in the multi-angle results. However in some situations they overestimate the coherence of neutrinos traveling along different trajectories. More sophisticated quantum closures may improve the agreement between the inexpensive moment-based methods and the multi-angle approach.Comment: Accepted in Physical Review

    Money and mental wellbeing : a longitudinal study of medium-sized lottery wins

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    One of the famous questions in social science is whether money makes people happy. We offer new evidence by using longitudinal data on a random sample of Britons who receive medium-sized lottery wins of between £1000 and £120,000 (that is, up to approximately US$ 200,000). When compared to two control groups – one with no wins and the other with small wins – these individuals go on eventually to exhibit significantly better psychological health. Two years after a lottery win, the average measured improvement in mental wellbeing is 1.4 GHQ points

    ‘We have to wait in a queue for our turn quite a bit’ Examining children’s physical activity during primary physical education lessons

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    The overall purpose of this study was to examine children’s physical activity (PA) during primary physical education (PE). This was achieved through the following two research objectives: (1) to measure children’s PA, lesson context and teacher promotion of PA during PE lessons; and (2) to explore teachers’ and children’s perspectives on PA levels during PE lessons. Evidence suggests that children’s PA during PE is below recommended levels and further research is required to understand the reasons why. Through a mixed method design, 138 children were observed using the System for Observing Fitness and Instruction Time, 80 children participated in group interviews, and 13 teachers were interviewed, across three primary schools in England. Findings indicated that the mean percentage of lesson time allocated to moderate to vigorous PA (MVPA) was 42.4% and the average lesson length was 35.3 minutes. Qualitative themes identified were: ‘knowledge and beliefs’; ‘teacher pedagogy’; and ‘teacher development’. The findings indicate that a change in perspective is needed, which includes a focus on PA during primary PE lessons. Intervention work is required that targets teachers’ knowledge and beliefs towards PE along with the development of effective teaching strategies. However, this needs to be grounded in an ecological approach which will allow researchers and schools to target the various levels of influence. It is strongly recommended that interventions are grounded in behaviour change theory, as this study indicates that sharing knowledge about pedagogical strategies to increase children’s MVPA does not necessarily produce changes in teachers’ behaviours

    The SDO Education and Outreach (E/PO) Program: Changing Perceptions One Program at a Time

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    The Solar Dynamics Observatory (SDO) Education and Public Outreach (E/PO) program began as a series of discrete efforts implemented by each of the instrument teams and has evolved into a well-rounded program with a full suite of national and international programs. The SDO E/PO team has put forth much effort in the past few years to increase our cohesiveness by adopting common goals and increasing the amount of overlap between our programs. In this paper, we outline the context and overall philosophy for our combined programs, present a brief overview of all SDO E/PO programs along with more detailed highlight of a few key programs, followed by a review of our results up to date. Concluding is a summary of the successes, failures, and lessons learned that future missions can use as a guide, while further incorporating their own content to enhance the public's knowledge and appreciation of NASA?s science and technology as well as its benefit to society

    The Solar Dynamics Observatory (SDO) Education and Outreach (E/PO) Program: Changing Perceptions One Program at a Time

    Get PDF
    We outline the context and overall philosophy for the combined Solar Dynamics Observatory (SDO) Education and Public Outreach (E/PO) program, present a brief overview of all SDO E/PO programs along with more detailed highlights of a few key programs, followed by a review of our results to date, conclude a summary of the successes, failures, and lessons learned, which future missions can use as a guide, while incorporating their own content to enhance the public's knowledge and appreciation of science and technology as well as its benefit to society

    Islet ÎČ-Cells Deficient in Bcl-xL Develop but Are Abnormally Sensitive to Apoptotic Stimuli

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    OBJECTIVE: Bcl-xL is an antiapoptotic member of the Bcl-2 family of proteins and a potent regulator of cell death. We investigated the importance of Bcl-xL for beta-cells by deleting the Bcl-x gene specifically in beta-cells and analyzing their survival in vivo and in culture. RESEARCH DESIGN AND METHODS: Islets with beta-cells lacking the Bcl-x gene were assessed in vivo by histology and by treatment of mice with low-dose streptozotocin (STZ). Islets were isolated by collagenase digestion and treated in culture with the apoptosis inducers staurosporine, thapsigargin, gamma-irradiation, proinflammatory cytokines, or Fas ligand. Cell death was assessed by flow cytometric analysis of subgenomic DNA. RESULTS: Bcl-xL-deficient beta-cells developed but were abnormally sensitive to apoptosis induced in vivo by low-dose STZ. Although a small proportion of beta-cells still expressed Bcl-xL, these did not have a survival advantage over their Bcl-xL-deficient neighbors. Islets appeared normal after collagenase isolation and whole-islet culture. They were, however, abnormally sensitive in culture to a number of different apoptotic stimuli including cytotoxic drugs, proinflammatory cytokines, and Fas ligand. CONCLUSIONS: Bcl-xL expression in beta-cells is dispensible during islet development in the mouse. Bcl-xL is, however, an important regulator of beta-cell death under conditions of synchronous stress. Bcl-xL expression at physiological levels may partially protect beta-cells from apoptotic stimuli, including apoptosis because of mediators implicated in type 1 diabetes and death or degeneration of transplanted islets

    Scientific publishing and the reading of science in nineteenth-century Britain: a historiographical survey and guide to sources

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    [FIRST PARAGRAPH] It is now generally accepted that both the conception and practices of natural enquiry in the Western tradition underwent a series of profound developments in the late eighteenth and early nineteenth century—developments which have been variously characterized as a ‘second scientific revolution’ and, much more tellingly, as the ‘invention of science’. As several authors have argued, moreover, a crucial aspect of this change consisted in the distinctive audience relations of the new sciences. While eighteenth-century natural philosophy was distinguished by an audience relation in which, as William Whewell put it, ‘a large and popular circle of spectators and amateurs [felt] themselves nearly upon a level, in the value of their trials and speculations, with more profound thinkers’, the science which was invented in the late eighteenth and early nineteenth century was, as Simon Schaffer has argued, marked by the ‘emergence of disciplined, trained cadres of research scientists’ clearly distinguished from a wider, exoteric public. Similarly, Jan Golinski argues that the ‘emergence of new instrumentation and a more consolidated social structure for the specialist community’ for early nineteenth-century chemistry was intimately connected with the transformation in the role of its public audience to a condition of relative passivity. These moves were underpinned by crucial epistemological and rhetorical shifts—from a logic of discovery, theoretically open to all, to a more restrictive notion of discovery as the preserve of scientific ‘genius’, and from an open-ended philosophy of ‘experience’ to a far more restrictive notion of disciplined ‘expertise’. Both of these moves were intended to do boundary work, restricting the community active in creating and validating scientific knowledge, and producing a passive public
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