19 research outputs found
Bogoliubov Coefficients of 2D Charged Black Holes
We exactly calculate the thermal distribution and temperature of Hawking
radiation for a two-dimensional charged dilatonic black hole after it has
settled down to an "equilibrium" state. The calculation is carried out using
the Bogoliubov coefficients. The background of the process is furnished by a
preexisting black hole and not by collapsing matter as considered by Giddings
and Nelson for the case of a Schwarzschild black hole. Furthermore, the
vanishing of the temperature and/or the Hawking radiation in the extremal case
is obtained as a regular limit of the general case.Comment: 9 pages, 1 eps figur
Charged black holes in quadratic gravity
Iterative solutions to fourth-order gravity describing static and
electrically charged black holes are constructed. Obtained solutions are
parametrized by two integration constants which are related to the electric
charge and the exact location of the event horizon. Special emphasis is put on
the extremal black holes. It is explicitly demonstrated that in the extremal
limit, the exact location of the (degenerate) event horizon is given by \rp =
|e|. Similarly to the classical Reissner-Nordstr\"om solution, the
near-horizon geometry of the charged black holes in quadratic gravity, when
expanded into the whole manifold, is simply that of Bertotti and Robinson.
Similar considerations have been carried out for the boundary conditions of
second type which employ the electric charge and the mass of the system as seen
by a distant observer. The relations between results obtained within the
framework of each method are briefly discussed
Statistical Mechanics of Nonuniform Magnetization Reversal
The magnetization reversal rate via thermal creation of soliton pairs in
quasi-1D ferromagnetic systems is calculated. Such a model describes e.g. the
time dependent coercivity of elongated particles as used in magnetic recording
media. The energy barrier that has to be overcome by thermal fluctuations
corresponds to a soliton-antisoliton pair whose size depends on the external
field. In contrast to other models of first order phase transitions such as the
phi^4 model, an analytical expression for this energy barrier is found for all
values of the external field. The magnetization reversal rate is calculated
using a functional Fokker-Planck description of the stochastic magnetization
dynamics. Analytical results are obtained in the limits of small fields and
fields close to the anisotropy field. In the former case the hard-axis
anisotropy becomes effectively strong and the magnetization reversal rate is
shown to reduce to the nucleation rate of soliton-antisoliton pairs in the
overdamped double sine-Gordon model. The present theory therefore includes the
nucleation rate of soliton-antisoliton pairs in the double sine-Gordon chain as
a special case. These results demonstrate that for elongated particles, the
experimentally observed coercivity is significantly lower than the value
predicted by the standard theories of N\'eel and Brown.Comment: 21 pages RevTex 3.0 (twocolumn), 6 figures available on request, to
appear in Phys Rev B, Dec (1994
Modeling quark-hadron duality for relativistic, confined fermions
We discuss a model for the study of quark-hadron duality in inclusive
electron scattering based on solving the Dirac equation numerically for a
scalar confining linear potential and a vector color Coulomb potential. We
qualitatively reproduce the features of quark-hadron duality for all potentials
considered, and discuss similarities and differences to previous models that
simplified the situation by treating either the quarks or all particles as
scalars. We discuss the scaling results for PWIA and FSI, and the approach to
scaling using the analog of the Callan-Gross relation for y-scaling.Comment: 38 pages, 21 figure
Reducing the environmental impact of surgery on a global scale: systematic review and co-prioritization with healthcare workers in 132 countries
Background
Healthcare cannot achieve net-zero carbon without addressing operating theatres. The aim of this study was to prioritize feasible interventions to reduce the environmental impact of operating theatres.
Methods
This study adopted a four-phase Delphi consensus co-prioritization methodology. In phase 1, a systematic review of published interventions and global consultation of perioperative healthcare professionals were used to longlist interventions. In phase 2, iterative thematic analysis consolidated comparable interventions into a shortlist. In phase 3, the shortlist was co-prioritized based on patient and clinician views on acceptability, feasibility, and safety. In phase 4, ranked lists of interventions were presented by their relevance to high-income countries and low–middle-income countries.
Results
In phase 1, 43 interventions were identified, which had low uptake in practice according to 3042 professionals globally. In phase 2, a shortlist of 15 intervention domains was generated. In phase 3, interventions were deemed acceptable for more than 90 per cent of patients except for reducing general anaesthesia (84 per cent) and re-sterilization of ‘single-use’ consumables (86 per cent). In phase 4, the top three shortlisted interventions for high-income countries were: introducing recycling; reducing use of anaesthetic gases; and appropriate clinical waste processing. In phase 4, the top three shortlisted interventions for low–middle-income countries were: introducing reusable surgical devices; reducing use of consumables; and reducing the use of general anaesthesia.
Conclusion
This is a step toward environmentally sustainable operating environments with actionable interventions applicable to both high– and low–middle–income countries
Reliability of the English version of the painDETECT questionnaire
Background: The painDETECT questionnaire (PD-Q) has been used widely for the identification of neuropathic pain (NeP); however, the reliability of the English version of the PD-Q has never been investigated. Objective: This study aimed to determine the reliability of the PD-Q pre- (T0) and immediately post- (T1) clinical consultation and at one-week follow-up (T2). Methods: We recruited 157 patients attending a Neurosurgery Spinal Clinic and Pain Management Department. Minor changes to PD-Q instructions were made to facilitate patient understanding; however, no changes to individual items or scoring were made. Intraclass correlation coefficients (ICCs) were used to assess the reliability of PD-Q total scores between T0–T1 and T0–T2; weighted kappa (κ) was used to assess the agreement of PD-Q classifications (unlikely NeP, ambiguous, likely NeP) between all time-points. To ensure stability of clinical pain, patients scoring ≤2 or ≥6 on the Patient Global Impression Scale (PGIC) at T2 were excluded from the T0–T2 analysis. Results: Accounting for missing data and exclusions (change in PGIC score), data for 136 individuals (mean [SD] age: 56.8 [15.2]; 54% male) was available, of whom n = 129 were included in the T0–T1 and n = 69 in the T0–T2 comparisons. There was almost perfect agreement between the PD-Q total scores at T0–T1 time-points (ICC 0.911; 95% CI: 0.882–0.941) and substantial agreement at T0–T2 (ICC 0.792; 95% CI: 0.703–0.880). PD-Q classifications demonstrated substantial agreement for T0–T1 (weighted κ: 0.771; 95% CI: 0.683–0.858) and for T0–T2 (weighted κ: 0.691; 95% CI: 0.553–0.830). Missing data was accounted in 13% of our cohort and over 42% of our patients drew multiple pain areas on the PD-Q body chart. Conclusion: The English version of the PD-Q is reliable as a screening tool for NeP. The validity of the questionnaire is still in question and has to be investigated in future studies
Perceptions of Top-Level Judo Coaches on Training and Performance
The main goal of this project was to assess top-level judo coaches' perceptions on two capital elements in coaching: training and competition management. 41 experienced, high-level coaches from Europe, Asia and America agreed to participate. An open-ended questionnaire was selected as the assessment instrument. The two main topics (training and competition) were divided in two areas: methodology and access to high-level performance, and combat strategies and coaches' roles and tasks during combat, respectively. Results showed that in order to access high-level performance, judo training must consider the most effective techniques in competition, judokas must develop their special technique and they must work on physical, technical, tactical and psychological aspects. Regarding competition, combat strategy is determined by the opponent, and coaches must provide precise information to their judokas, focusing on their grip and body alignment