13,857 research outputs found

    Brans-Dicke supergravity and the Lambda naturalness problem

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    The successful ΛCDM\Lambda CDM cosmological model requires a small but nonzero Λ\Lambda which appears to have an unnaturally small value compared to the supersymmetry breaking scale, typically O(10−60)m3/24O(10^{-60}) m_{3/2}^4 for m3/2∼10TeVm_{3/2} \sim 10 TeV. We explore the possibility of solving this naturalness problem in a special class of no-scale supergravity models which arise from a supersymmetric version of Brans-Dicke gravity, in which the Volkov and Brans-Dicke multiplets may be identified. These may be embedded in compactified string models, with the Brans-Dicke scalar given by the combination of dilaton and compactification breathing modes which leaves the 4 dimensional gauge couplings fixed. Assuming that 4 dimensional physics has an approximate symmetry under changes in this mode broken only by couplings between the low energy and gravitational or string sectors, the main one loop contribution to Λ\Lambda cancels between Brans-Dicke and gravitational (conformal compensator) F terms, and the leading contributions to Λ\Lambda now appear to be O(m3/28mp−4)O(m_{3/2}^8 m_{p}^{-4)}, enabling a natural reconciliation between observational and particle physics estimates for Λ\Lambda. The Brans-Dicke scalar has a range O(m3/2−1)O(m_{3/2}^{-1}), lifting observational constraints on scalar gravity in this scenario

    String condensation and high energy graviton scattering

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    A simple model of the quantum mechanics of a nucleating particle in the recently proposed string condensation mechanism is presented. This is based on a universal mechanical gauge field related to the string condensate, which behaves as a kind of fluid. String condensation is conjectured to prevent the formation of closed horizons in situations of extreme compression and thereby enable unitarity to be preserved in ultra-Planckian high energy scattering. A comparison is made with graviton scattering in the Dvali N-portrait of black holes and the subsequent Hawking evaporation process is discussed in this context. This gives an update on further work done on the topic presented in the talk ‘String condensation: Nemesis of Black Holes’ at Planck 2015

    Cohort profile of the UK Biobank: diagnosis and characteristics of cerebrovascular disease

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    Purpose: The UK Biobank is a large-scale biomedical resource, containing sociodemographic and medical information, including data on a previous diagnosis of stroke or transient ischaemic attack (TIA). We described these participants and their medication usage. Participants: We identified participants who either self-reported or were identified from a nurse-led interview, having suffered a stroke or a TIA and compared them against participants without stroke ort TIA. We assessed their risk factor burden (sex, age, deprivation, waist to hip ratio (WHR), hypertension, smoking, alcohol intake, diabetes, physical exercise and oral contraception use (oral contraceptive pill, OCP)) and medication usage. Findings: to date We studied 502 650 people (54.41% women), 6669 (1.23%) participants self-reported a stroke. The nurse-led interview identified 7669 (1.53%) people with stroke and 1781 (0.35%) with TIA. Hypertension, smoking, higher WHR, lower alcohol consumption and diabetes were all more common in people with cerebrovascular disease (p<0.0001 for each). Women with cerebrovascular disease were less likely to have taken the OCP (p=0.0002). People with cerebrovascular disease did more exercise (p=0.03). Antithrombotic medication was taken by 81% of people with stroke (both self-report and nurse-led responders) and 89% with TIA. For self-reported stroke, 63% were taking antithrombotic and cholesterol medications, 54% taking antithrombotic and antihypertensive medications and 46% taking all 3. For the nurse-led interview and TIA, these figures were 65%, 54% and 46%, and 70%, 53% and 45%, respectively. Future plans: The UK Biobank provides a large, generalisable and contemporary data source in a young population. The characterisation of the UK Biobank cohort with cerebrovascular disease will form the basis for ongoing research using this data source

    Designing a Green Roof for Ireland

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    A model is presented for the gravity-driven flow of rainwater descending through the soil layer of a green roof, treated as a porous medium on a at permeable surface representing an efficient drainage layer. A fully saturated zone is shown to occur. It is typically a thin layer, relative to the total soil thickness, and lies at the bottom of the soil layer. This provides a bottom boundary condition for the partially saturated upper zone. It is shown that after the onset of rainfall, well-defined fronts of water can descend through the soil layer. Also the rainwater flow is relatively quick compared with the moisture uptake by the roots of the plants in the roof. In a separate model the exchanges of water are described between the (smaller-scale) porous granules of soil, the roots and the rainwater in the inter-granule pores

    Standardised library instruction assessment: an institution-specific approach

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    Introduction We explore the use of a psychometric model for locally-relevant, information literacy assessment, using an online tool for standardised assessment of student learning during discipline-based library instruction sessions. Method A quantitative approach to data collection and analysis was used, employing standardised multiple-choice survey questions followed by individual, cognitive interviews with undergraduate students. The assessment tool was administered to five general education psychology classes during library instruction sessions. AnalysisDescriptive statistics were generated by the assessment tool. Results. The assessment tool proved a feasible means of measuring student learning. While student scores improved on every survey question, there was uneven improvement from pre-test to post-test for different questions. Conclusion Student scores showed more improvement for some learning outcomes over others, thus, spending time on fewer concepts during instruction sessions would enable more reliable evaluation of student learning. We recommend using digital learning objects that address basic research skills to enhance library instruction programmes. Future studies will explore different applications of the assessment tool, provide more detailed statistical analysis of the data and shed additional light on the significance of overall scores

    Teaching Population Health: Innovations in the integration of the healthcare and public health systems

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    Population health is a critical concept in healthcare delivery today. Many healthcare administrators are struggling to adapt their organization from fee-for-service to value delivery. Payers and patients expect healthcare leaders to understand how to deliver care under this new model. Health administration programs play a critical role in training future leaders of healthcare organizations to be adaptable and effective in this dynamic environment. The purpose of this research was to: (a) engage current educators of health administration students in a dialogue about the best practices of integrating the healthcare and public health systems; (b) identify the content and pedagogy for population health in the undergraduate and graduate curricula; and (c) discuss exemplar population health curriculum models, available course materials, and curriculum integration options. Authors conducted focus groups of participants attending this educational session at the 2017 annual AUPHA meeting. Qualitative analysis of the focus group discussions was performed and themes identified by a consensus process. Study findings provide validated recommendations for population health in the health administration curriculum. The identification of key content areas and pedagogical approaches serves to inform health educators as they prepare future health administrators to practice in this new era of population health

    Entanglement without nonlocality

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    We consider the characterization of entanglement from the perspective of a Heisenberg formalism. We derive an original two-party generalized separability criteria, and from this describe a novel physical understanding of entanglement. We find that entanglement may be considered as fundamentally a local effect, and therefore as a separable computational resource from nonlocality. We show how entanglement differs from correlation physically, and explore the implications of this new conception of entanglement for the notion of classicality. We find that this understanding of entanglement extends naturally to multipartite cases.Comment: 9 pages. Expanded introduction and sections on physical entanglement and localit

    Plasma properties and Stokes profiles during the lifetime of a photospheric magnetic bright point

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    Aims: to investigate the evolution of plasma properties and Stokes parameters in photospheric magnetic bright points using 3D magneto-hydrodynamical simulations and radiative diagnostics of solar granulation. Methods: simulated time-dependent radiation parameters and plasma properties were investigated throughout the evolution of a bright point. Synthetic Stokes profiles for the FeI 630.25 nm line were calculated, which allowed the evolution of the Stokes-I line strength and Stokes-V area and amplitude asymmetries to also be investigated. Results: our results are consistent with theoretical predictions and published observations describing convective collapse, and confirm this as the bright point formation process. Through degradation of the simulated data to match the spatial resolution of SOT, we show that high spatial resolution is crucial for the detection of changing spectro-polarimetric signatures throughout a magnetic bright point's lifetime. We also show that the signature downflow associated with the convective collapse process is reduced towards zero as the radiation intensity in the bright point peaks, due to the magnetic forces present restricting the flow of material in the flux tube.Comment: 14 pages, 12 figures, accepted to A&

    Pedagogy: How to best teach population health to future healthcare leaders

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    Our healthcare system is moving from a fee-for-service reimbursement model to one that provides payment for improvements in three areas related to care: quality, coordination, and cost. Healthcare organizations must use a population health approach when delivering care under this new paradigm. Health administration programs play a critical role in training future leaders of healthcare organizations to be adaptable and effective in this dynamic environment. The purpose of this research was to: (1) engage health administration educators in a dialogue about population health and its relevance to healthcare administration education; (2) describe pedagogical methods appropriate for teaching population health skills and abilities needed for successful careers in our healthcare environment; and (3) identify current student learning outcomes that participants can tailor to utilize in their undergraduate and graduate health management courses. Authors conducted focus groups of participants attending this educational session at the 2018 annual AUPHA meeting. Qualitative analysis of the focus group discussions identified themes by a consensus process. Study findings provide validated recommendations for population health in the health administration curriculum. The identification of pedagogical approaches serves to inform educators as they prepare future health administrators to practice in this new era of healthcare delivery
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