46,752 research outputs found
Ising analogue to compact-star matter
By constructing an Ising analogue of compact-star matter at sub-saturation
density we explored the effect of Coulomb frustration on the nuclear liquid-gas
phase transition. Our conclusions is twofold. First, the range of temperatures
where inhomogeneous phases form expands with increasing Coulomb-field strength.
Second, within the approximation of uniform electron distribution, the limiting
point upon which the phase-coexistence region ends does not exhibit any
critical behaviour. Possible astrophysics consequences and thermodynamical
connections are discussed.Comment: 4 pages, 3 figure
From energy-density functionals to mean field potentials: a systematic derivation
In this paper we present a systematic method to solve the variational problem
of the derivation of a self-consistent Kohn-Sham field from an arbitrary local
energy functional. We illustrate this formalism with an application in nuclear
physics and give the general mean field associated to the widely used Skyrme
effective interaction
Shot noise in semiclassical chaotic cavities
We construct a trajectory-based semiclassical theory of shot noise in clean
chaotic cavities. In the universal regime of vanishing Ehrenfest time \tE, we
reproduce the random matrix theory result, and show that the Fano factor is
exponentially suppressed as \tE increases. We demonstrate how our theory
preserves the unitarity of the scattering matrix even in the regime of finite
\tE. We discuss the range of validity of our semiclassical approach and point
out subtleties relevant to the recent semiclassical treatment of shot noise in
the universal regime by Braun et al. [cond-mat/0511292].Comment: Final version, to appear in Physical Review Letter
First-principles study of lattice instabilities in Ba_xSr_(1-x)TiO_3
Using first-principles calculations based on a variational density functional
perturbation theory, we investigate the lattice dynamics of solid solutions of
barium and strontium titanates. Averaging the information available for the
related pure compounds yields results equivalent to those obtained within the
virtual crystal approximation, providing frequencies which are a good
approximation to those computed for a (111) ordered supercell. Using the same
averaging technique we report the evolution of the ferroelectric and
antiferrodistortive instabilities with composition.Comment: 9 pages, 2 figures, Proceedings for Fundamental Physics of
Ferroelectrics, Aspen (CO), Feb. 13-20, 200
Avoiding the polarization catastrophe in LaAlO3 overlayers on SrTiO3(001) through a polar distortion
A pronounced uniform polar distortion extending over several unit cells
enables thin LaAlO3 overlayers on SrTiO3(001) to counteract the charge dipole
and thereby neutralize the "polarization catastrophe" that is suggested by
simple ion-counting. This unanticipated mechanism, obtained from density
functional theory calculations, allows several unit cells of the LaAlO3
overlayer to remain insulating (hence, fully ionic). The band gap of the
system, defined by occupied O states at the surface and unoccupied Ti 3d
states at the interface in some cases 20 \AA distant, decreases with
increasing thickness of the LaAlO3-film before an insulator-to-metal transition
and a crossover to an electronic reconstruction occurs at around five
monolayers of LaAlO3.Comment: 5 pages, 4 figures, submitted for publicatio
Macroeconomic and fiscal impact of the risk capital allowance
The study, produced in response to a request made by the federal government, examines the economic impact of the risk capital allowance. More particularly, it assesses the extent to which the objectives of the law of 22 June 2005 introducing an allowance for risk capital in the Belgian corporation tax system have been achieved. The study gives a brief presentation of the measures introduced by this law. It analyses the influence of these measures on the financial structure of corporations, their effect on the Belgian coordination centres – whose beneficial tax regime will soon be abolished – and their macroeconomic impact particularly investment and employment. Their budgetary implications on the basis of both macroeconomic and microeconomic data is then examined.corporation tax in Belgium, tax allowance, risk capital, coordination centres
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Validation of a Clinical Scoring System for Outcome Prediction in Dogs with Acute Kidney Injury Managed by Hemodialysis.
BackgroundA scoring system for outcome prediction in dogs with acute kidney injury (AKI) recently has been developed but has not been validated.HypothesisThe scoring system previously developed for outcome prediction will accurately predict outcome in a validation cohort of dogs with AKI managed with hemodialysis.AnimalsOne hundred fifteen client-owned dogs with AKI.MethodsMedical records of dogs with AKI treated by hemodialysis between 2011 and 2015 were reviewed. Dogs were included only if all variables required to calculate the final predictive score were available, and the 30-day outcome was known. A predictive score for 3 models was calculated for each dog. Logistic regression was used to evaluate the association of the final predictive score with each model's outcome. Receiver operating curve (ROC) analyses were performed to determine sensitivity and specificity for each model based on previously established cut-off values.ResultsHigher scores for each model were associated with decreased survival probability (P < .001). Based on previously established cut-off values, 3 models (models A, B, C) were associated with sensitivities/specificities of 73/75%, 71/80%, and 75/86%, respectively, and correctly classified 74-80% of the dogs.Conclusions and clinical relevanceAll models were simple to apply and allowed outcome prediction that closely corresponded with actual outcome in an independent cohort. As expected, accuracies were slightly lower compared with those from the previously reported cohort used initially to develop the models
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