1,031 research outputs found

    Late-time expansion in the semiclassical theory of the Hawking radiation

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    We give a detailed treatment of the back-reaction effects on the Hawking spectrum in the late-time expansion within the semiclassical approach to the Hawking radiation. We find that the boundary value problem defining the action of the modes which are regular at the horizon admits in general the presence of caustics. We show that for radii less that a certain critical value rcr_c no caustic occurs for all values of the wave number and time and we give a rigorous lower bound on such a critical value. We solve the exact system of non linear equations defining the motion, by an iterative procedure rigorously convergent at late times. The first two terms of such an expansion give the O(ω/M)O(\omega/M) correction to the Hawking spectrum.Comment: 17 pages, 1 figure, LaTex, typos corrected, one intermediate formula adde

    Toda Fields on Riemann Surfaces: remarks on the Miura transformation

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    We point out that the Miura transformation is related to a holomorphic foliation in a relative flag manifold over a Riemann Surface. Certain differential operators corresponding to a free field description of WW--algebras are thus interpreted as partial connections associated to the foliation.Comment: AmsLatex 1.1, 10 page

    The Complex Langevin method: When can it be trusted?

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    We analyze to what extent the complex Langevin method, which is in principle capable of solving the so-called sign problems, can be considered as reliable. We give a formal derivation of the correctness and then point out various mathematical loopholes. The detailed study of some simple examples leads to practical suggestions about the application of the method.Comment: 14 pages, including several eps figures and tables; clarification and minor corrections added, to appear in PR

    Measurement of motherinfant interactions and the home environment in a European setting: preliminary results from a cross-cultural

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    Background: Infant development is adversely affected in the context of postnatal depression. This relationship may be mediated by both the nature of early motherinfant interactions and the quality of the home environment. Aim: To establish the usefulness of the Global Ratings Scales of MotherInfant Interaction and the InfantToddler version of the Home Observation for the Measurement of the Environment (ITHOME), and to test expected associations of the measures with characteristics of the social context and with major or minor depression. Method: Both assessments were administered postnatally in four European centres; 144 mothers were assessed with the Global Ratings Scales and 114 with the ITHOME. Affective disorder was assessed by means of the Structured Clinical Interview for DSMIV Disorders. Results: Analyses of motherinfant interaction indicated no main effect for depression but maternal sensitivity to infant behaviour was associated with better infant communication, especially for women who were not depressed. Poor overall emotional support also reduced sensitivity scores. Poor support was also related to poorer ITHOME scores, but there was no effect of depression. Conclusions: The Global Ratings Scales were effectively applied but there was lessCIHR184pub152

    Trunk Control And Standing Tolerance Of A Patient With Paraparesis As A Result Of Transverse Myelitis And Mycotic Aneurysm Rupture: A Case Report

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    Background and Purpose: Transverse myelitis (TM) is a rare condition in which the spinal cord becomes inflamed resulting in pain, paraparesis or paraplegia, impaired sensation, and/or impaired autonomic function. Approximately two-thirds recover with mild to moderate symptoms, but one-third are left with severe and disabling symptoms. Cerebral mycotic aneurysm (CMA) rupture is a brain injury due to a burst artery resulting in diminished blood supply to the brain. There is literature on beneficial physical therapy (PT) intervention progressions following brain injury, such as bed mobility strategies and pre-gait activities, but there is little published on PT for impairments as a result of concurrent TM and CMA ruptures. The purpose of this case report was to describe the PT interventions provided to a patient with paraparesis as a result of TM and multiple CMA ruptures to progress toward achieving his goals of standing and ambulating with a standard walker and bilateral knee-ankle-foot-orthoses (KAFOs). Case Description: The 28-year-old male patient had been seen for two years at an outpatient clinic with an accredited brain injury program. The patient encountered several barriers throughout his rehabilitation, such as repairs to his KAFOs and low bone mineral density, which resulted in a decrease in standing tolerance over time. Outcomes: The Brain Injury Assessment Tool (BIAT) and manual muscle testing were used to document changes throughout the patient’s period of care. No significant changes were observed. Discussion: This patient, despite minimal improvements over a two-year period, may have the potential to increase his trunk control and standing tolerance if he has an extended period of time with no barriers to his rehabilitation

    Deformation Theory of Holomorphic Vector Bundles, Extended Conformal Symmetry and Extensions of 2D Gravity

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    Developing on the ideas of R. Stora and coworkers, a formulation of two dimensional field theory endowed with extended conformal symmetry is given, which is based on deformation theory of holomorphic and Hermitian spaces. The geometric background consists of a vector bundle EE over a closed surface Σ\Sigma endowed with a holomorphic structure and a Hermitian structure subordinated to it. The symmetry group is the semidirect product of the automorphism group Aut(E){\rm Aut}(E) of EE and the extended Weyl group Weyl(E){\rm Weyl}(E) of EE and acts on the holomorphic and Hermitian structures. The extended Weyl anomaly can be shifted into an automorphism chirally split anomaly by adding to the action a local counterterm, as in ordinary conformal field theory. The dependence on the scale of the metric on the fiber of EE is encoded in the Donaldson action, a vector bundle generalization of the Liouville action. The Weyl and automorphism anomaly split into two contributions corresponding respectively to the determinant and projectivization of EE. The determinant part induces an effective ordinary Weyl or diffeomorphism anomaly and the induced central charge can be computed.Comment: 49 pages, plain TeX. A number of misprints have been correcte

    On Holomorphic Factorization in Asymptotically AdS 3D Gravity

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    This paper studies aspects of ``holography'' for Euclidean signature pure gravity on asymptotically AdS 3-manifolds. This theory can be described as SL(2,C) CS theory. However, not all configurations of CS theory correspond to asymptotically AdS 3-manifolds. We show that configurations that do have the metric interpretation are parameterized by the so-called projective structures on the boundary. The corresponding asymptotic phase space is shown to be the cotangent bundle over the Schottky space of the boundary. This singles out a ``gravitational'' sector of the SL(2,C) CS theory. It is over this sector that the path integral has to be taken to obtain the gravity partition function. We sketch an argument for holomorphic factorization of this partition function.Comment: 32+1 pages, no figures; (v2) one reference added, a statement regarding priorities modified; (v3) presentational changes, an important sign mistake correcte

    Chern-Simons States at Genus One

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    We present a rigorous analysis of the Schr\"{o}dinger picture quantization for the SU(2)SU(2) Chern-Simons theory on 3-manifold torus×\timesline, with insertions of Wilson lines. The quantum states, defined as gauge covariant holomorphic functionals of smooth su(2)su(2)-connections on the torus, are expressed by degree 2k2k theta-functions satisfying additional conditions. The conditions are obtained by splitting the space of semistable su(2)su(2)-connections into nine submanifolds and by analyzing the behavior of states at four codimension 11 strata. We construct the Knizhnik-Zamolodchikov-Bernard connection allowing to compare the states for different complex structures of the torus and different positions of the Wilson lines. By letting two Wilson lines come together, we prove a recursion relation for the dimensions of the spaces of states which, together with the (unproven) absence of states for spins\s>{_1\over^2}level implies the Verlinde dimension formula.Comment: 33 pages, IHES/P

    Demographic patterns and outcomes of patients in level I trauma centers in three international trauma systems

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    Introduction: Trauma systems were developed to improve the care for the injured. The designation and elements comprising these systems vary across countries. In this study, we have compared the demographic patterns and patient outcomes of Level I trauma centers in three international trauma systems. Methods: International multicenter prospective trauma registry-based study, performed in the University Medical Center Utrecht (UMCU), Utrecht, the Netherlands, John Hunter Hospital (JHH), Newcastle, Australia, and Harborview Medical Center (HMC), Seattle, the United States. Inclusion: patients =18 years, admitted in 2012, registered in the institutional trauma registry. Results: In UMCU, JHH, and HMC, respectively, 955, 1146, and 4049 patients met the inclusion criteria of which 300, 412, and 1375 patients with Injury Severity Score (ISS) > 15. Mean ISS was higher in JHH (13.5; p < 0.001) and HMC (13.4; p < 0.001) compared to UMCU (11.7). Unadjusted mortality: UMCU = 6.5 %, JHH = 3.6 %, and HMC = 4.8 %. Adjusted odds of death: JHH = 0.498 [95 % confidence interval (CI) 0.303-0.818] and HMC = 0.473 (95 % CI 0.325-0.690) compared to UMCU. HMC compared to JHH was 1.002 (95 % CI 0.664-1.514). Odds of death patients ISS > 15: JHH = 0.507 (95 % CI 0.300-0.857) and HMC = 0.451 (95 % CI 0.297-0.683) compared to UMCU. HMC = 0.931 (95 % CI 0.608-1.425) compared to JHH. TRISS analysis: UMCU: Ws = 0.787, Z = 1.31, M = 0.87; JHH, Ws = 3.583, Z = 6.7, M = 0.89; HMC, Ws = 3.902, Z = 14.6, M = 0.84. Conclusion: This study demonstrated substantial differences across centers in patient characteristics and mortality, mainly of neurological cause. Future research must investigate whether the outcome differences remain with nonfatal and long-term outcomes. Furthermore, we must focus on the development of a more valid method to compare systems
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