1,733 research outputs found

    Constant threshold correction to electrically charged dilatonic black holes

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    We investigate the effect of a constant threshold correction to a general non-extreme, static, spherically symmetric, electrically charged black hole solution of the dilatonic Einstein-Maxwell Lagrangian, with an arbitrary coupling β\beta between the electromagnetic tensor and the dilaton field. For a small β\beta, an exact analytical solution is obtained. For an arbitrary β\beta, a close form solution, up to first order in the threshold correction, of the metric and the dilaton are presented. In the extremal limit, the close form solution is reduced to an exact analytical form.Comment: LaTex with RevTex, 8 page

    Anisotropic finite-size scaling analysis of a three-dimensional driven-diffusive system

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    We study the standard three-dimensional driven diffusive system on a simple cubic lattice where particle jumps along a given lattice direction are biased by an infinitely strong field, while those along other directions follow the usual Kawasaki dynamics. Our goal is to determine which of the several existing theories for critical behavior is valid. We analyze finite-size scaling properties using a range of system shapes and sizes far exceeding previous studies. Four different analytic predictions are tested against the numerical data. Binder and Wang's prediction does not fit the data well. Among the two slightly different versions of Leung, the one including the effects of a dangerous irrelevant variable appears to be better. Recently proposed isotropic finite-size scaling is inconsistent with our data from cubic systems, where systematic deviations are found, especially in scaling at the critical temperature.Comment: 12 pages, 14 PS figures, RevTeX; extensively revise

    Analysis of symmetrical components of harmonics for three phase power systems

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    Includes bibliographical references.Harmonic distortion of three phase power systems is caused by large amounts of electric power consumers using power electronic installations (e.g. drives and rectifiers). It has a number of undesirable consequences and has become an increasingly important problem with the rapid growth and ready availability of the power electronic devices and installations. A famous mathematical technique called "symmetrical components" was used to model the fundamental components of three phase systems. This method was extended to various harmonics. The aim of this thesis is to measure both the magnitude and phase angles of various harmonics which exist in three phase power systems, and to express them in symmetrical components. A digital electronics and microprocessor-based instrument was designed and constructed using the novel signal modulation technique called "+1 and -1" which was developed by the author of this thesis. This instrument was employed to achieve the above objectives

    Non-Perturbative States in Superstring Theories

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    Massless BPS-saturated states in toroidally compactified heterotic string were discussed first. Then, I constructed a large class of BPS-saturated states of toroidally compactified type II string theories. They were parametrized by four independent parameters. Both orthogonal and non-orthogonal intersections of non-perturbative states in the corresponding ten dimensional theories were discussed. Phenomenologically, I considered the string effect in the form of threshold corrections on dilatonic charged black holes, and the superpotential of N=1 supergravity theoryComment: Dissertation (1997

    Severe Spastic Contractures and Diabetes Mellitus Independently Predict Subsequent Minimal Trauma Fractures Among Long-Term Care Residents

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    Design This was a longitudinal cohort study of prospectively collected data. Participants were followed from March 2007 to March 2016 or until death. Setting A 300-bed long-term care hospital in Hong Kong. Participants All long-term care residents who were in need of continuous medical and nursing care for their activities of daily living. Measurements Information on patients' demographic data, severe contracture defined as a decrease of 50% or more of the normal passive range of joint movement of the joint, and severe limb spasticity defined by the Modified Ashworth Scale higher than grade 3, medical comorbidities, functional status, cognitive status, nutritional status including body mass index and serum albumin, past history of fractures, were evaluated as potential risk factors for subsequent MTF. Results Three hundred ninety-six residents [148 males, mean ± standard deviation (SD), age = 79 ± 16 years] were included for analysis. The presence of severe contracture was highly prevalent among the study population: 91% of residents had at least 1 severe contracture, and 41% of residents had severe contractures involving all 4 limbs. Moreover, there were a significant proportion of residents who had severe limb spasticity with the elbow flexors (32.4%) and knee flexors (33.9%) being the most commonly involved muscles. Twelve residents (3%) suffered from subsequent MTF over a median follow-up of 33 (SD = 30) months. Seven out of these 12 residents died during the follow-up period, with a mean survival of 17.8 months (SD = 12.6) after the fracture event. The following 2 factors were found to independently predict subsequent MTF in a multivariate Cox regression: bilateral severe spastic knee contractures (hazard ratio = 16.5, P < .0001, confidence interval 4.8–56.4) and diabetes mellitus (hazard ratio = 4.0. P = .018, confidence interval 1.3–12.7). Conclusions Severe spasticity and contractures are common morbidities in long-term care residents, and bilateral severe spastic knee contractures and diabetes mellitus are 2 independent predictors of subsequent MTF. Spasticity management and prevention of contractures, combined with educational programs for caregivers to identify the high-risk residents and apply proper handling techniques during routine care, may be helpful in reducing the risk of MTF in long-term care residents. Further large-scale longitudinal studies are needed to confirm these findings.published_or_final_versio
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