60,426 research outputs found

    A ducted wind turbine simulation model for building simulation

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    Power production is shifting away from centralized generation plants to production of heat and power at the point of demand. A technology that may play a part in this shift is the ducted wind turbine (DWT). The emergence of small building integrated micro turbines opens up the possibility of utilizing the differential pressures occurring around buildings for local power production. This paper describes work to develop and test a simple mathematical model of a ducted wind turbine and its integration within a building simulation tool. A case study in which the simulation model will be used to analyse of the likely power output from a building incorporating ducted wind turbines within the façade is also presented

    Break-up fragments excitation and the freeze-out volume

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    We investigate, in microcanonical multifragmentation models, the influence of the amount of energy dissipated in break-up fragments excitation on freeze-out volume determination. Assuming a limiting temperature decreasing with nuclear mass, we obtain for the Xe+Sn at 32 MeV/nucleon reaction [J. D. Frankland et al., Nucl. Phys. A689, 905 (2001); A689, 940 (2001)] a freeze-out volume almost half the one deduced using a constant limiting temperature.Comment: 11 pages, 6 figure

    Translated Poisson approximation to equilibrium distributions of Markov population processes

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    The paper is concerned with the equilibrium distributions of continuous-time density dependent Markov processes on the integers. These distributions are known typically to be approximately normal, and the approximation error, as measured in Kolmogorov distance, is of the smallest order that is compatible with their having integer support. Here, an approximation in the much stronger total variation norm is established, without any loss in the asymptotic order of accuracy; the approximating distribution is a translated Poisson distribution having the same variance and (almost) the same mean. Our arguments are based on the Stein-Chen method and Dynkin's formula.Comment: 18 page

    Thigh fat and muscle each contribute to excess cardiometabolic risk in South Asians, independent of visceral adipose tissue.

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    OBJECTIVE: To compare fat distribution and associations between fat depots and cardiometabolic traits in South Asians and Europeans. METHODS: Five hundred and fourteen South Asians and 669 Europeans, aged 56-86. Questionnaires, record review, blood testing, and coronary artery calcification scores provided diabetes and clinical plus subclinical coronary heart disease (CHD) diagnoses. Abdominal visceral (VAT) and subcutaneous adipose tissue, thigh subcutaneous adipose tissue (TSAT), intermuscular and intramuscular thigh fat and thigh muscle were measured by CT. RESULTS: Accounting for body size, South Asians had greater VAT and TSAT than Europeans, but less thigh muscle. Associations between depots and disease were stronger in South Asians than Europeans. In multivariable analyses in South Asians, VAT was positively associated with diabetes and CHD, while TSAT and thigh muscle were protective for diabetes, and thigh muscle for CHD. Differences in VAT and thigh muscle only partially explained the excess diabetes and CHD in South Asians versus Europeans. Insulin resistance did not account for the effects of TSAT or thigh muscle. CONCLUSIONS: Greater VAT and TSAT and lesser thigh muscle in South Asians contributed to ethnic differences in cardiometabolic disease. Effects of TSAT and thigh muscle were independent of insulin resistance

    Quantitative Stability of Linear Infinite Inequality Systems under Block Perturbations with Applications to Convex Systems

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    The original motivation for this paper was to provide an efficient quantitative analysis of convex infinite (or semi-infinite) inequality systems whose decision variables run over general infinite-dimensional (resp. finite-dimensional) Banach spaces and that are indexed by an arbitrary fixed set JJ. Parameter perturbations on the right-hand side of the inequalities are required to be merely bounded, and thus the natural parameter space is l(J)l_{\infty}(J). Our basic strategy consists of linearizing the parameterized convex system via splitting convex inequalities into linear ones by using the Fenchel-Legendre conjugate. This approach yields that arbitrary bounded right-hand side perturbations of the convex system turn on constant-by-blocks perturbations in the linearized system. Based on advanced variational analysis, we derive a precise formula for computing the exact Lipschitzian bound of the feasible solution map of block-perturbed linear systems, which involves only the system's data, and then show that this exact bound agrees with the coderivative norm of the aforementioned mapping. In this way we extend to the convex setting the results of [3] developed for arbitrary perturbations with no block structure in the linear framework under the boundedness assumption on the system's coefficients. The latter boundedness assumption is removed in this paper when the decision space is reflexive. The last section provides the aimed application to the convex case

    Corporate social responsibility in a burgeoning industry: a stakeholder analysis

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    Purpose: The purpose of this paper is to investigate the extent and significance of involvement of craft brewery operators in their community through the lens of the stakeholder theory (ST). In addition, differences between forms of involvement and demographic characteristics of operators and breweries are examined. Design/methodology/approach: As many as 218 operators of predominantly micro-craft breweries across the USA participated in an online questionnaire designed to gather their perceptions. Findings: While paying taxes was participants’ main perceived form of contribution, providing an artisan-made product, the significance of the craft brewery as a community “hub”, and that of increasing the number of leisure alternatives also emerged. A further 52.8 per cent of participants indicated contributing US$100,000 or more to the community annually. Statistically significant differences were revealed, for instance, based on craft breweries’ production volume, and the level of financial contribution. Various associations between operators’ perceived contributions and the ST theses were established in regard to cooperative interests (descriptive), stakeholder management (instrumental), and moral principles (normative). Originality/value: First, by examining corporate social responsibility (CSR) in the craft brewing industry and among predominantly smaller firms, the study addresses two under-researched areas. Second, a refinement of the ST in the context of the craft brewing industry is proposed, highlighting the links between ST-based theses and the findings. Third, the study contributes to three different types of literature: micro and small business, craft brewing entrepreneurship, and CSR. © 2018, Emerald Publishing Limited

    Comments on scaling limits of 4d N=2 theories

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    We revisit the study of the maximally singular point in the Coulomb branch of 4d N=2 SU(N) gauge theory with N_f=2n flavors for N_f= 2, we find that the low-energy physics is described by two non-trivial superconformal field theories coupled to a magnetic SU(2) gauge group which is infrared free. (In the special case n=2, one of these theories is a theory of free hypermultiplets.) This observation removes a possible counter example to a conjectured a-theorem.Comment: 13 page

    Estimation of maximal oxygen consumption and heart rate recovery using the Tecumseh sub-maximal step test and their relationship to cardiovascular risk factors

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    BACKGROUND: Maximum aerobic capacity (VO2max) is associated with lower cardiovascular and total mortality. Step tests can be used to provide an estimate of (VO2max) in epidemiological or home-based studies. We compared different methods of estimation of VO2max and heart rate recovery and evaluated the relationship of these estimates with cardiovascular risk factors. METHODS: Data were analysed from 2286 participants in the Tecumseh Community Health Study (>16 y and <70 y) who performed a step test. VO2max was estimated from heart rate using three methods and the results compared. The magnitude of heart rate recovery (HRR) and the time constant of recovery based on different time intervals post-exercise were also estimated. RESULTS: Estimated VO2max showed good or poor agreement depending on the method used. VO2max correlated inversely with systolic blood pressure (SBP), body mass index (BMI), total cholesterol, blood glucose following a 100 g oral load (PLG) and Framingham risk score. In a multivariable model age sex, cigarette smoking, SBP, BMI and PLG were significantly inversely associated with VO2max. Correlations with risk factors were strongest for HRR measured over the first 30 s of recovery. Only the time constant calculated from the 3 min post-exercise period correlated significantly with risk factors. CONCLUSIONS: The Tecumseh step test can be used to provide estimates of VO2max and heart rate recovery. Estimated VO2max was inversely associated with higher systolic BP, higher BMI and worse glucose tolerance. Measurements of HRR over the first 30 s and the time constant calculate from the first 3 min of recovery correlate most closely with risk factors

    Ethnic Differences in Associations Between Blood Pressure and Stroke in South Asian and European Men.

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    It is unknown whether associations between blood pressure (BP) and stroke vary between Europeans and South Asians, despite higher stroke rates in the latter. We report findings from a UK cohort study of 1375 European and 1074 South Asian men, not receiving antihypertensive medication, aged 40 to 69 years at baseline (1988-1991). Assessment included BP, blood tests, anthropometry, and questionnaires. Incident stroke was established at 20 years from death certification, hospital and primary care records, and participant report. South Asians had higher systolic BP, diastolic BP, and mean arterial pressure than Europeans, and similar pulse pressure. Associations between systolic BP or diastolic BP and stroke were stronger in South Asians than Europeans, after adjustment for age, smoking status, waist/hip ratio, total/high-density lipoprotein-cholesterol ratio, diabetes mellitus, fasting glucose, physical activity, and heart rate (systolic BP: Europeans [odds ratio, 1.22; 95% confidence interval, 0.98-1.51], South Asians [1.56; 1.24-1.95]; ethnic difference P=0.04; diastolic BP: Europeans [0.90; 0.71-1.13], South Asians [1.68; 1.32-2.15]; P<0.001). Hemodynamic correlates of stroke risk differed by ethnicity: in combined models, mean arterial pressure but not pulse pressure was detrimentally associated with stroke in South Asians, whereas the converse was true for Europeans. The combination of hyperglycemia and hypertension appeared particularly detrimental for South Asians. There are marked ethnic differences in associations between BP parameters and stroke. Undue focus on systolic BP for risk prediction, and current age and treatment thresholds may be inappropriate for individuals of South Asian ancestry
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