324 research outputs found

    Tensions and Luscher Terms for (2+1)-dimensional k-strings from Holographic Models

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    The leading term for the energy of a bound state of k-quarks and k-antiquarks is proportional to its separation L. These k-string configurations have a Luscher term associated with their quantum fluctuations which is typically a 1/L correction to the energy. We review the status of tensions and Luscher terms in the context of lattice gauge theory, Hamiltonian methods, and gauge/gravity correspondence. Furthermore we explore how different representations of the k-string manifest themselves in the gauge/gravity duality. We calculate the Luscher term for a strongly coupled SU(N) gauge theory in (2+1) dimensions using the gauge/gravity correspondence. Namely, we compute one-loop corrections to a probe D4-brane embedded in the Cvetic, Gibbons, Lu, and Pope supergravity background. We investigate quantum fluctuations of both the bosonic and the fermionic sectors.Comment: 39 pages, reference added, same version to be published in JHE

    Implementing exercise in cancer care: study protocol to evaluate a community-based exercise program for people with cancer

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    Background Clinical research has established the efficacy of exercise in reducing treatment-related side-effects and increasing wellbeing in people with cancer. Major oncology organisations have identified the importance of incorporating exercise in comprehensive cancer care but information regarding effective approaches to translating evidence into practice is lacking. This paper describes the implementation of a community-based exercise program for people with cancer and the protocol for program evaluation. Methods/Design The Life Now Exercise program is a community-based exercise intervention designed to mitigate and rehabilitate the adverse effects of cancer and its treatment and improve physical and psychosocial wellbeing in people with cancer. Involvement in the program is open to people with any diagnosis of cancer who are currently receiving treatment or within 2 years of completing treatment. The 3-month intervention consists of twice weekly group-based exercise sessions administered in community exercise clinics under the supervision of exercise physiologists trained to deliver the program. Evaluation of the program involves measures of uptake, safety, adherence and effectiveness (including cost effectiveness) as assessed at the completion of the program and 6 months follow-up. Discussion To bridge the gap between research and practice, the Life Now Exercise program was designed and implemented to provide people with cancer access to evidence-based exercise medicine. The framework for program implementation and evaluation offers insight into the development of feasible, generalizable and sustainable supportive care services involving exercise. Community-based exercise programs specifically designed for people with cancer are necessary to facilitate adherence to international guidelines advising patients to participate in high-quality exercise

    Radiative transfer effects in primordial hydrogen recombination

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    The calculation of a highly accurate cosmological recombination history has been the object of particular attention recently, as it constitutes the major theoretical uncertainty when predicting the angular power spectrum of Cosmic Microwave Background anisotropies. Lyman transitions, in particular the Lyman-alpha line, have long been recognized as one of the bottlenecks of recombination, due to their very low escape probabilities. The Sobolev approximation does not describe radiative transfer in the vicinity of Lyman lines to a sufficient degree of accuracy, and several corrections have already been computed in other works. In this paper, the impact of some previously ignored radiative transfer effects is calculated. First, the effect of Thomson scattering in the vicinity of the Lyman-alpha line is evaluated, using a full redistribution kernel incorporated into a radiative transfer code. The effect of feedback of distortions generated by the optically thick deuterium Lyman-alpha line blueward of the hydrogen line is investigated with an analytic approximation. It is shown that both effects are negligible during cosmological hydrogen recombination. Secondly, the importance of high-lying, non overlapping Lyman transitions is assessed. It is shown that escape from lines above Ly-gamma and frequency diffusion in Ly-beta and higher lines can be neglected without loss of accuracy. Thirdly, a formalism generalizing the Sobolev approximation is developed to account for the overlap of the high-lying Lyman lines, which is shown to lead to negligible changes to the recombination history. Finally, the possibility of a cosmological hydrogen recombination maser is investigated. It is shown that there is no such maser in the purely radiative treatment presented here.Comment: 23 pages, 4 figures, to be submitted to PR

    Study Protocol - Alcohol Management Plans (AMPs) in remote indigenous communities in Queensland: their impacts on injury, violence, health and social indicators and their cost-effectiveness

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    BACKGROUND: In 2002/03 the Queensland Government responded to high rates of alcohol-related harm in discrete Indigenous communities by implementing alcohol management plans (AMPs), designed to include supply and harm reduction and treatment measures. Tighter alcohol supply and carriage restrictions followed in 2008 following indications of reductions in violence and injury. Despite the plans being in place for over a decade, no comprehensive independent review has assessed to what level the designed aims were achieved and what effect the plans have had on Indigenous community residents and service providers. This study will describe the long-term impacts on important health, economic and social outcomes of Queensland’s AMPs. METHODS/DESIGN: The project has two main studies, 1) outcome evaluation using de-identified epidemiological data on injury, violence and other health and social indicators for across Queensland, including de-identified databases compiled from relevant routinely-available administrative data sets, and 2) a process evaluation to map the nature, timing and content of intervention components targeting alcohol. Process evaluation will also be used to assess the fidelity with which the designed intervention components have been implemented, their uptake and community responses to them and their perceived impacts on alcohol supply and consumption, injury, violence and community health. Interviews and focus groups with Indigenous residents and service providers will be used. The study will be conducted in all 24 of Queensland’s Indigenous communities affected by alcohol management plans. DISCUSSION: This evaluation will report on the impacts of the original aims for AMPs, what impact they have had on Indigenous residents and service providers. A central outcome will be the establishment of relevant databases describing the parameters of the changes seen. This will permit comprehensive and rigorous surveillance systems to be put in place and provided to communities empowering them with the best credible evidence to judge future policy and program requirements for themselves. The project will inform impending alcohol policy and program adjustments in Queensland and other Australian jurisdictions.The study was funded by the National Health and Medical Research Council of Australia (NHMRC, Project Grant #APP1042532), with additional support from the Australian Primary Health Care Research Institute-funded Centre for Research Excellence for the Prevention of Chronic Conditions in Rural and Remote High Risk Populations at James Cook University & University Adelaide. Dr Caryn West is a National Health and Medical Research Council of Australia Early Career Research Post – Doctoral Fellow (NHMRC ECR, #APP1070931).Associate Professor Clough holds a NHMRC Career Development Award (#APP1046773)

    Alcohol management plans in Aboriginal and Torres Strait Islander (Indigenous) Australian communities in Queensland: community residents have experienced favourable impacts but also suffered unfavourable ones

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    Background: In Australia, 'Alcohol Management Plans' (AMPs) provide the policy infrastructure for State and Commonwealth Governments to address problematic alcohol use among Aboriginal and Torres Strait Islanders. We report community residents' experiences of AMPs in 10 of Queensland's 15 remote Indigenous communities.\ud \ud Methods: This cross-sectional study used a two-stage sampling strategy: N = 1211; 588 (48%) males, 623 (52%) females aged ≥18 years in 10 communities. Seven propositions about 'favourable' impacts and seven about 'unfavourable' impacts were developed from semi-structured interviews. For each proposition, one-sample tests of proportions examined participant agreement and multivariable binary logistic regressions assessed influences of gender, age (18–24, 25–44, 45–64, ≥65 years), residence (≥6 years), current drinking and Indigenous status. Confirmatory factor analyses estimated scale reliability (ρ), item loadings and covariances.\ud \ud Results: Slim majorities agreed that: AMPs reduced violence (53%, p = 0.024); community a better place to live (54%, 0.012); and children were safer (56%, p < 0.001). More agreed that: school attendance improved (66%, p < 0.001); and awareness of alcohol's harms increased (71%, p < 0.001). Participants were equivocal about improved personal safety (53%, p = 0.097) and reduced violence against women (49%, p = 0.362). The seven 'favourable' items reliably summarized participants' experiences of reduced violence and improved community amenity (ρ = 0.90).\ud \ud Stronger agreement was found for six 'unfavourable' items: alcohol availability not reduced (58%, p < 0.001); drinking not reduced (56%, p < 0.001)); cannabis use increased (69%, p < 0.001); more binge drinking (73%, p < 0.001); discrimination experienced (77%, p < 0.001); increased fines, convictions and criminal records for breaching restrictions (90%, p < 0.001). Participants were equivocal (51% agreed, p = 0.365) that police could enforce restrictions effectively. 'Unfavourable' items were not reliably reflected in one group (ρ = 0.48) but in: i) alcohol availability and consumption not reduced and ii) criminalization and discrimination.\ud \ud In logistic regressions, longer-term (≥ 6 years) residents more likely agreed that violence against women had reduced and that personal safety had improved but also that criminalization and binge drinking had increased. Younger people disagreed that their community was a better place to live and strongly agreed about discrimination. Current drinkers' views differed little from the sample overall.\ud \ud Conclusions: The present Government review provides an opportunity to reinforce 'favourable' outcomes while targeting: illicit alcohol, treatment and diversion services and reconciliation of criminalization and discrimination issues.\ud \u

    Brane decay of a (4+n)-dimensional rotating black hole: spin-0 particles

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    In this work, we study the `scalar channel' of the emission of Hawking radiation from a (4+n)-dimensional, rotating black hole on the brane. We numerically solve both the radial and angular part of the equation of motion for the scalar field, and determine the exact values of the absorption probability and of the spheroidal harmonics, respectively. With these, we calculate the particle, energy and angular momentum emission rates, as well as the angular variation in the flux and power spectra -- a distinctive feature of emission during the spin-down phase of the life of the produced black hole. Our analysis is free from any approximations, with our results being valid for arbitrarily large values of the energy of the emitted particle, angular momentum of the black hole and dimensionality of spacetime. We finally compute the total emissivities for the number of particles, energy and angular momentum and compare their relative behaviour for different values of the parameters of the theory.Comment: 24 pages, 13 figure

    An empirical approach to selecting community-based alcohol interventions:combining research evidence, rural community views and professional opinion

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    <p>Abstract</p> <p>Background</p> <p>Given limited research evidence for community-based alcohol interventions, this study examines the intervention preferences of rural communities and alcohol professionals, and factors that influence their choices.</p> <p>Method</p> <p>Community preferences were identified by a survey of randomly selected individuals across 20 regional Australian communities. The preferences of alcohol professionals were identified by a survey of randomly selected members of the Australasian Professional Society on Alcohol and Other Drugs. To identify preferred interventions and the extent of support for them, a budget allocation exercise was embedded in both surveys, asking respondents to allocate a given budget to different interventions. Tobit regression models were estimated to identify the characteristics that explain differences in intervention preferences.</p> <p>Results</p> <p>Community respondents selected school programs most often (88.0%) and allocated it the largest proportion of funds, followed by promotion of safer drinking (71.3%), community programs (61.4%) and police enforcement of alcohol laws (60.4%). Professionals selected GP training most often (61.0%) and allocated it the largest proportion of funds, followed by school programs (36.6%), community programs (33.8%) and promotion of safer drinking (31.7%). Community views were susceptible to response bias. There were no significant predictors of professionals' preferences.</p> <p>Conclusions</p> <p>In the absence of sufficient research evidence for effective community-based alcohol interventions, rural communities and professionals both strongly support school programs, promotion of safer drinking and community programs. Rural communities also supported police enforcement of alcohol laws and professionals supported GP training. The impact of a combination of these strategies needs to be rigorously evaluated.</p

    The on-orbit performance of the Orbiting Carbon Observatory-2 (OCO-2) instrument and its radiometrically calibrated products

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    The Orbiting Carbon Observatory-2 (OCO-2) carries and points a three-channel imaging grating spectrometer designed to collect high-resolution, co-boresighted spectra of reflected sunlight within the molecular oxygen (O_2) A-band at 0.765 microns and the carbon dioxide (CO_2) bands at 1.61 and 2.06 microns. These measurements are calibrated and then combined into soundings that are analyzed to retrieve spatially resolved estimates of the column-averaged CO_2 dry-air mole fraction, XCO_2. Variations of XCO_2 in space and time are then analyzed in the context of the atmospheric transport to quantify surface sources and sinks of CO_2. This is a particularly challenging remote-sensing observation because all but the largest emission sources and natural absorbers produce only small (< 0.25 %) changes in the background XCO_2 field. High measurement precision is therefore essential to resolve these small variations, and high accuracy is needed because small biases in the retrieved XCO_2 distribution could be misinterpreted as evidence for CO_2 fluxes. To meet its demanding measurement requirements, each OCO-2 spectrometer channel collects 24 spectra s^(−1) across a narrow ( 17 000), dynamic range (∼ 10^4), and sensitivity (continuum signal-to-noise ratio > 400). The OCO-2 instrument performance was extensively characterized and calibrated prior to launch. In general, the instrument has performed as expected during its first 18 months in orbit. However, ongoing calibration and science analysis activities have revealed a number of subtle radiometric and spectroscopic challenges that affect the yield and quality of the OCO-2 data products. These issues include increased numbers of bad pixels, transient artifacts introduced by cosmic rays, radiance discontinuities for spatially non-uniform scenes, a misunderstanding of the instrument polarization orientation, and time-dependent changes in the throughput of the oxygen A-band channel. Here, we describe the OCO-2 instrument, its data products, and its on-orbit performance. We then summarize calibration challenges encountered during its first 18 months in orbit and the methods used to mitigate their impact on the calibrated radiance spectra distributed to the science community
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