11,664 research outputs found
Negative modes and the thermodynamics of Reissner-Nordstr\"om black holes
We analyse the problem of negative modes of the Euclidean section of the
Reissner-Nordstr\"om black hole in four dimensions. We find analytically that a
negative mode disappears when the specific heat at constant charge becomes
positive. The sector of perturbations analysed here is included in the
canonical partition function of the magnetically charged black hole. The result
obeys the usual rule that the partition function is only well-defined when
there is local thermodynamical equilibrium. We point out the difficulty in
quantising Einstein-Maxwell theory, where the so-called conformal factor
problem is considerably more intricate. Our method, inspired by hep-th/0608001,
allows us to decouple the divergent gauge volume and treat the metric
perturbations sector in a gauge-invariant way.Comment: 24 pages, 1 figure; v2 minor changes to fit published versio
Representation of Nelson Algebras by Rough Sets Determined by Quasiorders
In this paper, we show that every quasiorder induces a Nelson algebra
such that the underlying rough set lattice is algebraic. We
note that is a three-valued {\L}ukasiewicz algebra if and only if
is an equivalence. Our main result says that if is a Nelson
algebra defined on an algebraic lattice, then there exists a set and a
quasiorder on such that .Comment: 16 page
Estado Confusional Agudo após Corticoterapia Inalada
Background: The connection between corticotherapy and neuropsychiatric symptoms is
widely known, being one of the first questions
we need to assess when presenting with first
episode psychiatric symptoms or confusional
state.
Aims: To date, data on cases related to inhaled
corticotherapy and neuropsychiatric effects is
scarce. In this paper we describe a rare case in
a young woman.
Methods: The clinical case presented led us
to try to understand the data published on the
subject in order to discuss it in greater length.
Results and Conclusions: We present and
discuss a 27-year-old patient’s case, with no
previous psychiatric disease, who was admitted to our Psychiatric ward after the onset of
severe acute behavioural disturbance characterized by aggressiveness, visual and auditory
hallucinatory activity, misidentification and
altered conscience status. It was later found
that seven days earlier she had been prescribed
inhaled corticotherapy for a minor respiratory
infection. A few days after corticotherapy withdrawal, the clinical symptoms improved significantly.info:eu-repo/semantics/publishedVersio
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A submillimetre wavelength spectral line search of the Orion molecular cloud core
A submillimetre wavelength molecular line search of the Orion molecular cloud has been made covering a total of about 5 percent of the frequency range 342.8 - 358.6 GHz. This search, coupled with the authors' previous observations of submillimetre transitions in this cloud, has led to the detection of 22 transitions of 14 molecular species, of which 16 are reported here for the first time. No unidentified lines have been detected in the present search. Mapping observations have been obtained for several of the lines and, in the case of H2CO the authors have been able to compare the present data with that obtained from other telescopes, to estimate the density and abundance in the emitting region
Primary and secondary scintillation measurements in a xenon Gas Proportional Scintillation Counter
NEXT is a new experiment to search for neutrinoless double beta decay using a
100 kg radio-pure high-pressure gaseous xenon TPC. The detector requires
excellent energy resolution, which can be achieved in a Xe TPC with
electroluminescence readout. Hamamatsu R8520-06SEL photomultipliers are good
candidates for the scintillation readout. The performance of this
photomultiplier, used as VUV photosensor in a gas proportional scintillation
counter, was investigated. Initial results for the detection of primary and
secondary scintillation produced as a result of the interaction of 5.9 keV
X-rays in gaseous xenon, at room temperature and at pressures up to 3 bar, are
presented. An energy resolution of 8.0% was obtained for secondary
scintillation produced by 5.9 keV X-rays. No significant variation of the
primary scintillation was observed for different pressures (1, 2 and 3 bar) and
for electric fields up to 0.8 V cm-1 torr-1 in the drift region, demonstrating
negligible recombination luminescence. A primary scintillation yield of 81 \pm
7 photons was obtained for 5.9 keV X-rays, corresponding to a mean energy of 72
\pm 6 eV to produce a primary scintillation photon in xenon.Comment: 16 pages, 10 figures, accepted for publication in JINS
Classical diffusion in double-delta-kicked particles
We investigate the classical chaotic diffusion of atoms subjected to {\em
pairs} of closely spaced pulses (`kicks) from standing waves of light (the
-KP). Recent experimental studies with cold atoms implied an
underlying classical diffusion of type very different from the well-known
paradigm of Hamiltonian chaos, the Standard Map.
The kicks in each pair are separated by a small time interval , which together with the kick strength , characterizes the transport.
Phase space for the -KP is partitioned into momentum `cells' partially
separated by momentum-trapping regions where diffusion is slow. We present here
an analytical derivation of the classical diffusion for a -KP
including all important correlations which were used to analyze the
experimental data.
We find a new asymptotic () regime of `hindered' diffusion:
while for the Standard Map the diffusion rate, for , oscillates about the uncorrelated, rate , we find
analytically, that the -KP can equal, but never diffuses faster than,
a random walk rate.
We argue this is due to the destruction of the important classical
`accelerator modes' of the Standard Map.
We analyze the experimental regime , where
quantum localisation lengths are affected by fractal
cell boundaries. We find an approximate asymptotic diffusion rate , in correspondence to a regime in the Standard Map
associated with 'golden-ratio' cantori.Comment: 14 pages, 10 figures, error in equation in appendix correcte
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