633 research outputs found
Information measures of hydrogenic systems, Laguerre polynomials and spherical harmonics
AbstractFisher's information and Shannon's entropy are two complementary information measures of a probability distribution. Here, the probability distributions which characterize the quantum-mechanical states of a hydrogenic system are analyzed by means of these two quantities. These distributions are described in terms of Laguerre polynomials and spherical harmonics, whose characteristics are controlled by the three integer quantum numbers of the corresponding states. We have found the explicit expression for the Fisher information, and a lower bound for the Shannon entropy with the help of an isoperimetric inequality
Spinning Strings, Black Holes and Stable Closed Timelike Geodesics
The existence and stability under linear perturbation of closed timelike
curves in the spacetime associated to Schwarzschild black hole pierced by a
spinning string are studied. Due to the superposition of the black hole, we
find that the spinning string spacetime is deformed in such a way to allow the
existence of closed timelike geodesics.Comment: 5 pages, RevTex4, some corrections and new material adde
Configuration Complexities of Hydrogenic Atoms
The Fisher-Shannon and Cramer-Rao information measures, and the LMC-like or
shape complexity (i.e., the disequilibrium times the Shannon entropic power) of
hydrogenic stationary states are investigated in both position and momentum
spaces. First, it is shown that not only the Fisher information and the
variance (then, the Cramer-Rao measure) but also the disequilibrium associated
to the quantum-mechanical probability density can be explicitly expressed in
terms of the three quantum numbers (n, l, m) of the corresponding state.
Second, the three composite measures mentioned above are analytically,
numerically and physically discussed for both ground and excited states. It is
observed, in particular, that these configuration complexities do not depend on
the nuclear charge Z. Moreover, the Fisher-Shannon measure is shown to
quadratically depend on the principal quantum number n. Finally, sharp upper
bounds to the Fisher-Shannon measure and the shape complexity of a general
hydrogenic orbital are given in terms of the quantum numbers.Comment: 22 pages, 7 figures, accepted i
Stability of Closed Timelike Curves in Goedel Universe
We study, in some detail, the linear stability of closed timelike curves in
the Goedel metric. We show that these curves are stable. We present a simple
extension (deformation) of the Goedel metric that contains a class of closed
timelike curves similar to the ones associated to the original Goedel metric.
This extension correspond to the addition of matter whose energy-momentum
tensor is analyzed. We find the conditions to have matter that satisfies the
usual energy conditions. We study the stability of closed timelike curves in
the presence of usual matter as well as in the presence of exotic matter
(matter that does satisfy the above mentioned conditions). We find that the
closed timelike curves in Goedel universe with or whithout the inclusion of
regular or exotic matter are also stable under linear perturbations. We also
find a sort of structural stability.Comment: 12 pages, 11 figures, RevTex, several typos corrected. GRG, in pres
Hypovitaminosis D in dogs with spirocercosis
BACKGROUND : Spirocercosis in dogs is characterized by esophageal nodules that can undergo neoplastic transformation.
Hypovitaminosis D has been associated with neoplasia formation. We hypothesized hypovitaminosis D in neoplastic
spirocercosis and that it could be a risk factor for neoplastic transformation.
OBJECTIVE : To measure and compare vitamin D status, assessed by serum 25-hydroxyvitamin D [25(OH)D] concentrations
in non-neoplastic (n = 25) and neoplastic (n = 26) spirocercosis client-owned dogs and healthy dogs (n = 24).
ANIMALS : Twenty-five non-neoplastic dogs, 26 neoplastic dogs, and 24 healthy dogs.
METHODS : Fifty-one dogs were randomly selected from 119 dogs diagnosed with spirocercosis presenting to our hospital,
and further divided into non-neoplastic or neoplastic groups. Exclusion criteria included dogs less than 1 year old, with
concurrent diseases, received corticosteroids, or treated prophylactically for spirocercosis. Serum 25(OH)D concentration
was measured by high-performance liquid chromatography. Spirocercosis dogsâ appetites were graded and compared.
RESULTS : Serum 25(OH)D concentrations were significantly different among all groups (P < .001). 25-Hydroxyvitamin
D concentrations were significantly lower in neoplastic group (median 30.7 nmol/L [range 14.7â62.2]) compared to nonneoplastic
(median 52.7 nmol/L [range 19.1â129.7, P < .05]) and healthy groups (median 74.6 nmol/L [range 37.4â130.5,
P < .005]). 25-hydroxyvitamin D concentrations were significantly lower in non-neoplastic spirocercosis dogs compared
to healthy ones (P < .05). Neoplastic and non-neoplastic spirocercosis dogs had similar appetite scores (P = 1.0). 25-
Hydroxyvitamin D concentrations were not significantly different between dogs with normal (P = .087) and abnormal
(P = .125) appetites within neoplastic and non-neoplastic spirocercosis groups.
CONCLUSIONS AND CLINICAL IMPORTANCE : Further studies are warranted to determine potential use of vitamin D treatment
in spirocercosis and explore role of hypovitaminosis D in pathogenesis of malignant transformation.http://onlinelibrary.wiley.com/journal/10.1111/(ISSN)1939-1676hb2014mn201
The design and evaluation of travelling gun irrigation systems: enrolador software
Technical Paperinfo:eu-repo/semantics/publishedVersio
Growth responses and accumulation of soluble sugars in Inga marginata Wild. (Fabaceae) subjected to flooding under contrasting light conditions
Measurement of and charged current inclusive cross sections and their ratio with the T2K off-axis near detector
We report a measurement of cross section and the first measurements of the cross section
and their ratio
at (anti-)neutrino energies below 1.5
GeV. We determine the single momentum bin cross section measurements, averaged
over the T2K -flux, for the detector target material (mainly
Carbon, Oxygen, Hydrogen and Copper) with phase space restricted laboratory
frame kinematics of 500 MeV/c. The
results are and $\sigma(\nu)=\left( 2.41\
\pm0.022{\rm{(stat.)}}\pm0.231{\rm (syst.)}\ \right)\times10^{-39}^{2}R\left(\frac{\sigma(\bar{\nu})}{\sigma(\nu)}\right)=
0.373\pm0.012{\rm (stat.)}\pm0.015{\rm (syst.)}$.Comment: 18 pages, 8 figure
Planck 2015 results. XXVII. The Second Planck Catalogue of Sunyaev-Zeldovich Sources
We present the all-sky Planck catalogue of Sunyaev-Zeldovich (SZ) sources detected from the 29 month full-mission data. The catalogue (PSZ2) is the largest SZ-selected sample of galaxy clusters yet produced and the deepest all-sky catalogue of galaxy clusters. It contains 1653 detections, of which 1203 are confirmed clusters with identified counterparts in external data-sets, and is the first SZ-selected cluster survey containing > confirmed clusters. We present a detailed analysis of the survey selection function in terms of its completeness and statistical reliability, placing a lower limit of 83% on the purity. Using simulations, we find that the Y5R500 estimates are robust to pressure-profile variation and beam systematics, but accurate conversion to Y500 requires. the use of prior information on the cluster extent. We describe the multi-wavelength search for counterparts in ancillary data, which makes use of radio, microwave, infra-red, optical and X-ray data-sets, and which places emphasis on the robustness of the counterpart match. We discuss the physical properties of the new sample and identify a population of low-redshift X-ray under- luminous clusters revealed by SZ selection. These objects appear in optical and SZ surveys with consistent properties for their mass, but are almost absent from ROSAT X-ray selected samples
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