16,578 research outputs found

    Comparative evaluation of predicted and measured performance of a 68-cubic meter truncated reverberant noise chamber

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    The performance of a medium size, truncated reverberation chamber is evaluated in detail. Chamber performance parameters are predicted, using classical acoustic theory, and are compared to results from actual chamber measurements. Discrepancies are discussed in relation to several available empirical corrections developed by other researchers. Of more practical interest is the confirmation of a recent theory stating that the present guide for the ratio of specimen volume to test chamber volume, approximately 10 percent, is overly conservative, and can be increased by a factor of at least 2 and possibly 3. Results and theoretical justification of these findings are presented

    Subthreshold micropulse laser versus standard laser for the treatment of central-involving diabetic macular oedema with central retinal thickness of <400\ub5: a cost-effectiveness analysis from the DIAMONDS trial

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    \ua9 Author(s) (or their employer(s)) 2023. Objectives To estimate the economic costs, health-related quality-of-life outcomes and cost-effectiveness of subthreshold micropulse laser (SML) versus standard laser (SL) for the treatment of diabetic macular oedema (DMO) with central retinal thickness (CRT) of <400\ub5. Design An economic evaluation was conducted within a pragmatic, multicentre, randomised clinical trial, DIAbetic Macular Oedema aNd Diode Subthreshold. Setting 18 UK Hospital Eye Services. Participants Adults with diabetes and centre involving DMO with CRT<400\ub5. Interventions Participants (n=266) were randomised 1:1 to receive SML or SL. Methods The base-case used an intention-to-treat approach conducted from a UK National Health Service (NHS) and personal social services (PSS) perspective. Costs (2019–2020 prices) were collected prospectively over the 2-year follow-up period. A bivariate regression of costs and quality-adjusted life-years (QALYs), with multiple imputation of missing data, was conducted to estimate the incremental cost per QALY gained and the incremental net monetary benefit of SML in comparison to SL. Sensitivity analyses explored uncertainty and heterogeneity in cost-effectiveness estimates. Results One participant in the SL arm withdrew consent for data to be used; data from the remaining 265 participants were included in analyses. Mean (SE) NHS and PSS costs over 24 months were \ua3735.09 (\ua3111.85) in the SML arm vs \ua31099.70 (\ua3195.40) in the SL arm (p=0.107). Mean (SE) QALY estimates were 1.493 (0.024) vs 1.485 (0.020), respectively (p=0.780), giving an insignificant difference of 0.008 QALYs. The probability SML is cost-effective at a threshold of \ua320 000 per QALY was 76%. Conclusions There were no statistically significant differences in EQ-5D-5L scores or costs between SML and SL. Given these findings and the fact that SML does not burn the retina, unlike SL and has equivalent efficacy to SL, it may be preferred for the treatment of people with DMO with CRT<400\ub5

    Casimir Effect in Hyperbolic Polygons

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    We derive a trace formula for the spectra of quantum mechanical systems in hyperbolic polygons which are the fundamental domains of discrete isometry groups acting in the two dimensional hyperboloid. Using this trace formula and the point splitting regularization method we calculate the Casimir energy for a scalar fields in such domains. The dependence of the vacuum energy on the number of vertexes is established.Comment: Latex, 1

    Association between rectal gonorrhoea and HIV incidence in men who have sex with men: a meta-analysis

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    Background: Incidence of rectal gonorrhoea (GC) has been hypothesised as a correlate of HIV exposure in prevention trials of men who have sex with men (MSM). High rectal GC incidence in MSM trials of new biomedical prevention drugs may provide supportive evidence for ongoing HIV risk. Empirical evidence of correlation between rectal GC and HIV incidence is needed to assess whether high rectal GC rates reliably correlate with high risk of HIV. // Methods: Rectal GC and HIV are routinely tested in sexual health clinics (SHCs) throughout England. Through routine surveillance data collected at visits to SHCs, we assessed HIV incidence and new rectal GC diagnoses in repeat visits by HIV-negative MSM between 2011 and 2018, predating widespread roll-out of pre-exposure prophylaxis. Meta-analysis regression assessed population-level association between HIV and rectal GC incidence over time. // Findings: Between 2011 and 2018, HIV and rectal GC incidence was assessed in 541 056 HIV-negative MSM attending SHCs in England. HIV incidence among MSM attending SHCs fell from 1.26/100 person-years (PYs) in 2011 to 0.28/100 PYs in 2018. Rectal GC rates increased from 3.5/100 PYs to 11.1/100 PYs over the same period. The rate of HIV incidence decreased by 22.3% for each percent increase in rectal GC (95% CI –30.8 to –14.7, p<0.001). // Interpretation: Among the population of MSM attending SHCs in England, rectal GC rates increased substantially while HIV incidence rates decreased between 2011 and 2018. HIV incidence likely decreased through expanded HIV testing, prompt antiretroviral treatment (ART) initiation and increased viral suppression in persons living with HIV, interventions that did not decrease rectal GC. Rectal GC may not be an ideal proxy for HIV incidence in trials, as HIV exposure risk is complex and context dependent, given effective HIV prevention interventions in MSM

    Vortices, Instantons and Branes

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    The purpose of this paper is to describe a relationship between the moduli space of vortices and the moduli space of instantons. We study charge k vortices in U(N) Yang-Mills-Higgs theories and show that the moduli space is isomorphic to a special Lagrangian submanifold of the moduli space of k instantons in non-commutative U(N) Yang-Mills theories. This submanifold is the fixed point set of a U(1) action on the instanton moduli space which rotates the instantons in a plane. To derive this relationship, we present a D-brane construction in which the dynamics of vortices is described by the Higgs branch of a U(k) gauge theory with 4 supercharges which is a truncation of the familiar ADHM gauge theory. We further describe a moduli space construction for semi-local vortices, lumps in the CP(N) and Grassmannian sigma-models, and vortices on the non-commutative plane. We argue that this relationship between vortices and instantons underlies many of the quantitative similarities shared by quantum field theories in two and four dimensions.Comment: 32 Pages, 4 Figure

    Soil carbon stock impacts following reversion of Miscanthus x giganteus and short rotation coppice willow commercial plantations into arable cropping

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    There are posited links between the establishment of perennial bioenergy, such as Short Rotation Coppice (SRC) willow and Miscanthus x giganteus, on low carbon soils and enhanced soil C sequestration. Sequestration provides additional climate mitigation, however, few studies have explored impacts on soil C stocks of bioenergy crop removal, thus the permanence of any sequestered C is unclear. This uncertainty has led some authors to question the handling of soil C stocks with carbon accounting e.g. through LCA. Here we provide additional data for this debate, reporting on the soil C impacts of the reversion (removal and return) to arable cropping of commercial SRC willow and Miscanthus across four sites in the UK, two for each bioenergy crop, with 8 reversions nested within these sites. Using a paired‐site approach, soil C stocks (0–1 m) were compared between 3 and 7 years after bioenergy crop removal. Impacts on soil C stocks varied, ranging from an increase of 70.16 ± 10.81 Mg C ha‐1 7 years after reversion of SRC willow to a decrease of 33.38 ± 5.33 Mg C ha‐1 3 years after reversion of Miscanthus compared to paired arable land. The implications for carbon accounting will depend on the method used to allocate this stock change between current and past land use. However, with, published life cycle assessment values for the lifetime C reduction provided by these crops ranging from 29.50 to 138.55 Mg C ha‐1, the magnitude of these changes in stock are significant. We discuss the potential underlying mechanisms driving variability in soil C stock change, including the age of bioenergy crop at removal, removal methods, and differences in the recalcitrant of the crop residues, and highlight the need to design management methods to limit negative outcomes

    Values of sexual behaviour in Central and Eastern Europe

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    Despite the profusion of social cognitive models for the prediction of sexual behaviour, we have only limited knowledge as to the role of individual values in predicting risky sexual activity. This study assessed the relationship between a recently developed value structure and sexual behaviour in the context of rising HIV infection in central and eastern Europe. Five hundred and three respondents (business people, doctors and nurses) from Estonia, Georgia, Hungary, Poland and Russia completed Schwartz’s Portrait Values Questionnaire and reported their condom use, partnership history and record of sexual disease. Results indicated that values had a moderate but consistent relationship with sexual behaviour, with riskier sexual activity reported by those high on Openness to Change, Hedonism and Self-Enhancement. These findings are discussed in the context of the need for culturally sensitive interventions in order to tackle the growing HIV epidemic in this region.This project was supported by a research grant from the Research Support Scheme operated by the Soros Foundation, Prague

    Scientific Opinion on the substantiation of health claims related to iron and formation of red blood cells and haemoglobin (ID 374, 2889), oxygen transport (ID 255), contribution to normal energy-yielding metabolism (ID 255), reduction of tiredness and fatigue (ID 255, 374, 2889), biotransformation of xenobiotic substances (ID 258), and activity of heart, liver and muscles (ID 397) pursuant to Article 13(1) of Regulation (EC) No 1924/2006

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    Following a request from the European Commission, the Panel on Dietetic Products, Nutrition and Allergies was asked to provide a scientific opinion on a list of health claims pursuant to Article 13 of Regulation (EC) No 1924/2006. This opinion addresses the scientific substantiation of health claims in relation to iron and formation of red blood cells and haemoglobin, oxygen transport, contribution to normal energy-yielding metabolism, reduction of tiredness and fatigue, biotransformation of xenobiotic substances and \u201cactivity of heart, liver and muscles\u201d. The scientific substantiation is based on the information provided by the Member States in the consolidated list of Article 13 health claims and references that EFSA has received from Member States or directly from stakeholders. The food constituent that is the subject of the health claims is iron. The Panel considers that iron is sufficiently characterised
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