24 research outputs found
A way to estimate the heavy quark thermalization rate from the lattice
The thermalization rate of a heavy quark is related to its momentum diffusion
coefficient. Starting from a Kubo relation and using the framework of the heavy
quark effective theory, we argue that in the large-mass limit the momentum
diffusion coefficient can be defined through a certain Euclidean correlation
function, involving color-electric fields along a Polyakov loop. Furthermore,
carrying out a perturbative computation, we demonstrate that the spectral
function corresponding to this correlator is relatively flat at small
frequencies. Therefore, unlike in the case of several other transport
coefficients, for which the narrowness of the transport peak makes analytic
continuation from Euclidean lattice data susceptible to severe systematic
uncertainties, it appears that the determination of the heavy quark
thermalization rate could be relatively well under control.Comment: 17 pages. v2: clarifications and references added, published versio
Black Holes in Cascading Theories: Confinement/Deconfinement Transition and other Thermal Properties
We present numerical evidence for a transition between the Klebanov-Strassler
background and a solution describing a black hole in the class of cascading
solutions in the chirally restored phase. We also present a number of
properties of this solution, including the running of the coupling constant,
the viscosity to entropy ratio and the drag force on a quark moving in this
background.Comment: 34 pages, 7 figures. Version to be published by JHE
Projected impacts of increased uptake of source control mitigation measures on agricultural diffuse pollution emissions to water and air
The authors gratefully acknowledge the funding provided by Defra project LM0304; Phase 2 of the Avon Demonstration Test Catchment. The DTC farm survey data were collected in conjunction with the Avon (Defra project WQ0211), Wensum (Defra project WQ0212) and Eden (Defra project WQ02010) DTC programmes. The Environment Agency kindly provided access to national GIS layers. The authors thank the experts included in the elicitation exercise for current implementation of source control measures
Prophylactic Use of Implantable Cardioverter-Defibrillators in the Prevention of Sudden Cardiac Death in Dialysis Patients
BACKGROUND: Patients with end-stage renal disease who are undergoing dialysis are reported to be at high risk of sudden cardiac death (SCD), and to date, no therapy has been shown to be effective in reducing this risk. The feasibility and value of prophylactic implantable cardioverter-defibrillator (ICD) implantation to prevent SCD is uncertain. METHODS: We conducted the ICD2 trial (Implantable Cardioverter-Defibrillator in Dialysis Patients), a prospective, randomized, controlled study investigating the value and safety of ICD implantation to prevent SCD in 200 patients on dialysis with a left ventricular ejection fraction â„35%, after adequate screening and optimization of other treatments. The primary end point was SCD. Secondary end points were all-cause mortality and ICD-related complications. RESULTS: The trial was stopped as per the recommendation of the data and safety monitoring board for futility reasons after inclusion of 188 patients, 97 in the ICD group and 91 in the control group. The median duration of follow-up was 6.8 years (interquartile range, 3.8-8.8 years). SCD occurred in 19 of 188 cases (10.1%), 11 of 97 in the ICD group and 8 of 91 in the control group. The cumulative SCD incidence at 5 years was 9.7% (95% CI, 3.3%-16.2%) in the ICD group and 7.9% (95% CI, 1.7-14.0%) in the control group, resulting in a hazard ratio of 1.32 (95% CI, 0.53-3.29; P=0.55). Overall, 99 of 188 patients died (52.7%), 52 in the ICD group and 47 in the control group. Five-year survival probability was 50.6% (95% CI, 39.8%-61.5%) in the ICD group and 54.5% (95% CI, 43.0-66.0%) in the control group, resulting in a hazard ratio of 1.02 (95% CI, 0.69-1.52; P=0.92). Among 80 patients who received an ICD, 25 adverse events related to ICD implantation occurred. CONCLUSIONS: In a well-screened and well-treated population undergoing dialysis, prophylactic ICD therapy did not reduce the rate of SCD or all-cause mortality, which remained high. CLINICAL TRIAL REGISTRATION: URL: http://www.controlled-trials.com . Unique identifier: ISRCTN20479861