8,423 research outputs found
Hawking radiation for non asymptotically flat dilatonic black holes using gravitational anomaly
The -dimensional scalar field action may be reduced, in the background
geometry of a black hole, to a 2-dimensional effective action. In the near
horizon region, it appears a gravitational anomaly: the energy-momentum tensor
of the scalar field is not conserved anymore. This anomaly is removed by
introducing a term related to the Hawking temperature of the black hole. Even
if the temperature term introduced is not covariant, a gauge transformation may
restore the covariance. We apply this method to compute the temperature of the
black hole of the dilatonic non asymptotically flat black holes. We compare the
results with those obtained through other methods.Comment: Latex file, 22 pages. Some discussions enlarged. New references.
Accepted for publication in the European Physical Journal
Neural Relax
We present an algorithm for data preprocessing of an associative memory
inspired to an electrostatic problem that turns out to have intimate relations
with information maximization
Clinical surveillance of thrombotic microangiopathies in Scotland, 2003-2005
The prevalence, incidence and outcomes of haemolytic uraemic syndrome (HUS) and thrombotic thrombocytopaenic purpura (TTP) are not well established in adults or children from prospective studies. We sought to identify both outcomes and current management strategies using prospective, national surveillance of HUS and TTP, from 2003 to 2005 inclusive. We also investigated the links between these disorders and factors implicated in the aetiology of HUS and TTP including infections, chemotherapy, and immunosuppression. Most cases of HUS were caused by verocytotoxin-producing Escherichia coli (VTEC), of which serotype O157 predominated, although other serotypes were identified. The list of predisposing factors for TTP was more varied although use of immunosuppressive agents and severe sepsis, were the most frequent precipitants. The study demonstrates that while differentiating between HUS and TTP is sometimes difficult, in most cases the two syndromes have quite different predisposing factors and clinical parameters, enabling clinical and epidemiological profiling for these disorders
Frustrated multiband superconductivity
We show that a clean multiband superconductor may display one or several
phase transitions with increasing temperature from or to frustrated
configurations of the relative phases of the superconducting order parameters.
These transitions may occur when more than two bands are involved in the
formation of the superconducting phase and when the number of repulsive
interband interactions is odd. These transitions are signalled by slope changes
in the temperature dependence of the superconducting gaps.Comment: 5 pages, 3 figure
Density-based mixing parameter for hybrid functionals
A very popular ab-initio scheme to calculate electronic properties in solids
is the use of hybrid functionals in density functional theory (DFT) that mixes
a portion of Fock exchange with DFT functionals. In spite of their success, a
major problem still remains, related to the use of one single mixing parameter
for all materials. Guided by physical arguments that connect the mixing
parameter to the dielectric properties of the solid, and ultimately to its band
gap, we propose a method to calculate this parameter from the electronic
density alone. This method is able to cut significantly the error of
traditional hybrid functionals for large and small gap materials, while
retaining a good description of structural properties. Moreover, its
implementation is simple and leads to a negligible increase of the
computational time.Comment: submitte
Crescimento de mudas de Didymopanax morototoni (Aublet.) Decne (morototó) em viveiro em diferentes misturas de solo.
bitstream/item/40427/1/Boletim-Pesquisa-57-CPATU.pd
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