1,846 research outputs found
Noncommutative Black Holes and the Singularity Problem
A phase-space noncommutativity in the context of a Kantowski-Sachs
cosmological model is considered to study the interior of a Schwarzschild black
hole. Due to the divergence of the probability of finding the black hole at the
singularity from a canonical noncommutativity, one considers a non-canonical
noncommutativity. It is shown that this more involved type of noncommutativity
removes the problem of the singularity in a Schwarzschild black hole.Comment: Based on a talk by CB at ERE2010, Granada, Spain, 6th-10th September
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Bio-mechanical risk factors for uterine prolapse among women living in the hills of west Nepal: A case-control study.
OBJECTIVE:To investigate whether heavy load carrying, wearing a patuka, and body position at work are risk factors for uterine prolapse among Nepali women. METHODS:Community-based case-control study of 448 women (170 cases of uterine prolapse; 278 controls) aged 18-60 years in Kaski district, Nepal was conducted. Women diagnosed with uterine prolapse were cases. Two controls were recruited for each case, frequency-matched by residential area and age. Multivariate logistic regression was used to investigate associations between outcome and exposures. RESULTS:No association of heavy load carrying with uterine prolapse was observed; women who never used a patuka had lower odds of uterine prolapse (odds ratio = 0.18, 95% confidence interval = 0.05-0.71). Women working in a sitting position had higher odds than those working in a standing position (odds ratio = 2.94, 95% confidence interval = 1.74-4.96), as did women who mainly worked in a bending position (odds ratio = 2.45, 95% confidence interval = 1.12-5.34). Housewives were more prone to uterine prolapse than women engaged in farming (odds ratio = 2.13, 95% confidence interval = 1.31-3.47). CONCLUSION:Using a patuka, occupation, and body position during work were all associated with uterine prolapse. No association was found with heavy load carrying, although that might be attributable to the cross-sectional nature of study recruitment
Entropic Gravity, Phase-Space Noncommutativity and the Equivalence Principle
We generalize E. Verlinde's entropic gravity reasoning to a phase-space
noncommutativity set-up. This allow us to impose a bound on the product of the
noncommutative parameters based on the Equivalence Principle. The key feature
of our analysis is an effective Planck's constant that naturally arises when
accounting for the noncommutative features of the phase-space.Comment: 12 pages. Version to appear at the Classical and Quantum Gravit
On the Integrability of the Bukhvostov-Lipatov Model
The integrability of the Bukhvostov-Lipatov four-fermion model is
investigated. It is shown that the classical model possesses a current of
Lorentz spin 3, conserved both in the bulk and on the half-line for specific
types of boundary actions. It is then established that the conservation law is
spoiled at the quantum level -- a fact that might indicate that the quantum
Bukhvostov-Lipatov model is not integrable, contrary to what was previously
believed.Comment: 11 pages, 1 figure, LaTeX2e, AMS; new references adde
Anak Krakatau triggers volcanic freezer in the upper troposphere
Volcanic activity occurring in tropical moist atmospheres can promote deep convection and trigger volcanic thunderstorms. These phenomena, however, are rarely observed to last continuously for more than a day and so insights into the dynamics, microphysics and electrification processes are limited. Here we present a multidisciplinary study on an extreme case, where volcanically-triggered deep convection lasted for six days. We show that this unprecedented event was caused and sustained by phreatomagmatic activity at Anak Krakatau volcano, Indonesia during 22-28 December 2018. Our modelling suggests an ice mass flow rate of similar to 5x10(6)kg/s for the initial explosive eruption associated with a flank collapse. Following the flank collapse, a deep convective cloud column formed over the volcano and acted as a 'volcanic freezer' containing similar to 3x10(9)kg of ice on average with maxima reaching similar to 10(10)kg. Our satellite analyses reveal that the convective anvil cloud, reaching 16-18km above sea level, was ice-rich and ash-poor. Cloud-top temperatures hovered around -80 degrees C and ice particles produced in the anvil were notably small (effective radii similar to 20 mu m). Our analyses indicate that vigorous updrafts (>50m/s) and prodigious ice production explain the impressive number of lightning flashes (similar to 100,000) recorded near the volcano from 22 to 28 December 2018. Our results, together with the unique dataset we have compiled, show that lightning flash rates were strongly correlated (R=0.77) with satellite-derived plume heights for this event
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