84 research outputs found
The Near-Horizon Limit of the Extreme Rotating d=5 Black Hole as a Homogenous Spacetime
We show that the spacetime of the near-horizon limit of the extreme rotating
d=5 black hole, which is maximally supersymmetric in N=2,d=5 supergravity for
any value of the rotation parameter j in [-1,1], is locally isomorphic to a
homogeneous non-symmetric spacetime corresponding to an element of the
1-parameter family of coset spaces SO(2,1)x SO(3)/SO(2)_j in which the subgroup
SO(2)_j is a combination of the two SO(2) subgroups of SO(2,1) and SO(3).Comment: Some points clarified and misprints corrected. Version to be
published in Classical and Quantum Gravit
Geometric Construction of Killing Spinors and Supersymmetry Algebras in Homogeneous Spacetimes
We show how the Killing spinors of some maximally supersymmetric supergravity
solutions whose metrics describe symmetric spacetimes (including and H-waves) can be easily constructed using purely geometrical and
group-theoretical methods. The calculation of the supersymmetry algebras is
extremely simple in this formalism.Comment: misprints corrected and references added. Version to appear in
Classical and Quantum Gravit
Thin-shell wormholes with a generalized Chaplygin gas in Einstein-Born-Infeld theory
We construct spherically symmetric thin-shell wormholes supported by a
generalized Chaplygin gas in Born-Infeld electrodynamics coupled to Einstein
gravity, and we analyze their stability under radial perturbations. For
different values of the Born-Infeld parameter and the charge, we compare the
results with those obtained in a previous work for Maxwell electrodynamics. The
stability region in the parameter space reduces and then disappears as the
value of the Born-Infeld parameter is modified in the sense of a larger
departure from Maxwell theory.Comment: 9 pages, 6 figures; v2: improved versio
The Risk of Malignant Degeneration of Müllerian Derivatives in PMDS: A Review of the Literature
Persistent Müllerian Duct Syndrome (PMDS) is a rare autosomal recessive disorder of sex development characterized by the presence of fallopian tubes, uterus and upper one-third of the vagina in individuals with XY genotype and normal male phenotype. The main complications of PMDS are infertility and the rare risk of malignant degeneration of both testicular and Müllerian derivatives. We report the case of a 49-year-old man who, during repair of an incisional hernia, was incidentally found to have a uterine-like structure posterior to the bladder. In the past at the age of 18 months, he had undergone bilateral orchidopexies for bilateral cryptorchidism. The intraoperative decision was to preserve the uterine-like structure and make a more accurate diagnosis postoperatively. Evaluation revealed an XY chromosome and imaging consistent with PMDS. The patient was informed about the risk of neoplastic transformation of the residual Müller ducts and was offered surgical treatment, which he declined. Subsequent follow-up imaging studies, including testicular and pelvic ultrasound, were negative for findings suggestive of malignant testicular and Mullerian derivative degeneration. A review of the international literature showed that, when a decision is taken to remove the Mullerian derivatives, laparoscopy and especially robotic surgery allow for the successful removal of Müllerian derivatives. Whenever the removal of these structures is not possible or the patient refuses to undergo surgery, it is necessary to inform the patient of the need for adequate follow-up. Patients should undergo regular pelvic imaging examination and MRI might be a better method for that purpose
Análisis y recomendaciones al sistema administrativo de la Universidad de El Salvador volumen II
La finalidad de este Informe es la de exponer, de un modo integral y objetivo, los diversos pormenores de la investigación científica efectuada en doce diferentes sistemas componentes del quehacer administrativo de la Universidad de El Salvado
Análisis y recomendaciones al sistema administrativo de la Universidad de El Salvador volumen I
La finalidad de este Informe es la de exponer, de un modo integral y objetivo, los diversos pormenores de la investigación científica efectuada en doce diferentes sistemas componentes del quehacer administrativo de la Universidad de El Salvador
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Cause of Death and Predictors of All-Cause Mortality in Anticoagulated Patients With Nonvalvular Atrial Fibrillation : Data From ROCKET AF
M. Kaste on työryhmän ROCKET AF Steering Comm jäsen.Background-Atrial fibrillation is associated with higher mortality. Identification of causes of death and contemporary risk factors for all-cause mortality may guide interventions. Methods and Results-In the Rivaroxaban Once Daily Oral Direct Factor Xa Inhibition Compared with Vitamin K Antagonism for Prevention of Stroke and Embolism Trial in Atrial Fibrillation (ROCKET AF) study, patients with nonvalvular atrial fibrillation were randomized to rivaroxaban or dose-adjusted warfarin. Cox proportional hazards regression with backward elimination identified factors at randomization that were independently associated with all-cause mortality in the 14 171 participants in the intention-to-treat population. The median age was 73 years, and the mean CHADS(2) score was 3.5. Over 1.9 years of median follow-up, 1214 (8.6%) patients died. Kaplan-Meier mortality rates were 4.2% at 1 year and 8.9% at 2 years. The majority of classified deaths (1081) were cardiovascular (72%), whereas only 6% were nonhemorrhagic stroke or systemic embolism. No significant difference in all-cause mortality was observed between the rivaroxaban and warfarin arms (P=0.15). Heart failure (hazard ratio 1.51, 95% CI 1.33-1.70, P= 75 years (hazard ratio 1.69, 95% CI 1.51-1.90, P Conclusions-In a large population of patients anticoagulated for nonvalvular atrial fibrillation, approximate to 7 in 10 deaths were cardiovascular, whereasPeer reviewe
Composition, Elastic Property and Packing Efficiency Predictions for Bulk Metallic Glasses in Binary, Ternary and Quaternary Systems
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