3,470 research outputs found
Ultraspinning instability of anti-de Sitter black holes
Myers-Perry black holes with a single spin in d>5 have been shown to be
unstable if rotating sufficiently rapidly. We extend the numerical analysis
which allowed for that result to the asymptotically AdS case. We determine
numerically the stationary perturbations that mark the onset of the
instabilities for the modes that preserve the rotational symmetries of the
background. The parameter space of solutions is thoroughly analysed, and the
onset of the instabilities is obtained as a function of the cosmological
constant. Each of these perturbations has been conjectured to represent a
bifurcation point to a new phase of stationary AdS black holes, and this is
consistent with our results.Comment: 22 pages, 7 figures. v2: Reference added. Matches published versio
Continuity, Deconfinement, and (Super) Yang-Mills Theory
We study the phase diagram of SU(2) Yang-Mills theory with one adjoint Weyl
fermion on R^3xS^1 as a function of the fermion mass m and the compactification
scale L. This theory reduces to thermal pure gauge theory as m->infinity and to
circle-compactified (non-thermal) supersymmetric gluodynamics in the limit
m->0. In the m-L plane, there is a line of center symmetry changing phase
transitions. In the limit m->infinity, this transition takes place at
L_c=1/T_c, where T_c is the critical temperature of the deconfinement
transition in pure Yang-Mills theory. We show that near m=0, the critical
compactification scale L_c can be computed using semi-classical methods and
that the transition is of second order. This suggests that the deconfining
phase transition in pure Yang-Mills theory is continuously connected to a
transition that can be studied at weak coupling. The center symmetry changing
phase transition arises from the competition of perturbative contributions and
monopole-instantons that destabilize the center, and topological molecules
(neutral bions) that stabilize the center. The contribution of molecules can be
computed using supersymmetry in the limit m=0, and via the
Bogomolnyi--Zinn-Justin (BZJ) prescription in the non-supersymmetric gauge
theory. Finally, we also give a detailed discussion of an issue that has not
received proper attention in the context of N=1 theories---the non-cancellation
of nonzero-mode determinants around supersymmetric BPS and KK
monopole-instanton backgrounds on R^3xS^1. We explain why the non-cancellation
is required for consistency with holomorphy and supersymmetry and perform an
explicit calculation of the one-loop determinant ratio.Comment: A discussion of the non-cancellation of the nonzero mode determinants
around supersymmetric monopole-instantons in N=1 SYM on R^3xS^1 is added,
including an explicit calculation. The non-cancellation is, in fact, required
by supersymmetry and holomorphy in order for the affine-Toda superpotential
to be reproduced. References have also been adde
Cytological Aspects of Pleural, Peritoneal and Pericardial Fluids From Patients With Systemic Lupus Erythematosus
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/74778/1/j.1365-2303.1992.tb00014.x.pd
Ultraspinning instability: the missing link
We study linearized perturbations of Myers-Perry black holes in d=7, with two
of the three angular momenta set to be equal, and show that instabilities
always appear before extremality. Analogous results are expected for all higher
odd d. We determine numerically the stationary perturbations that mark the
onset of instability for the modes that preserve the isometries of the
background. The onset is continuously connected between the previously studied
sectors of solutions with a single angular momentum and solutions with all
angular momenta equal. This shows that the near-extremality instabilities are
of the same nature as the ultraspinning instability of d>5 singly-spinning
solutions, for which the angular momentum is unbounded. Our results raise the
question of whether there are any extremal Myers-Perry black holes which are
stable in d>5.Comment: 19 pages. 1 figur
Off-hours admission and mortality in two pediatric intensive care units without 24-h in-house senior staff attendance
To compare risk-adjusted mortality of children non-electively admitted during off-hours with risk-adjusted mortality of children admitted during office hours to two pediatric intensive care units (PICUs) without 24-h in-house attendance of senior staff. Prospective observational study, performed between January 2003 and December 2007, in two PICUs without 24-h in-house attendance of senior staff, located in tertiary referral children's hospitals in the Netherlands. Standardized mortality rates (SMRs) of patients admitted during off-hours were compared to SMRs of patients admitted during office hours using Pediatric Index of Mortality (PIM1) and Pediatric Risk of Mortality (PRISM2) scores. Office hours were defined as week days between 8:00 a.m. and 6:00 p.m., with in-house attendance of senior staff, and off-hours as week days between 6:00 p.m. and 8:00 a.m., Saturdays, Sundays and public holidays, with one resident covering the PICU and senior staff directly available on-call. Of 3,212 non-elective patients admitted to the PICUs, 2,122 (66%) were admitted during off-hours. SMRs calculated according to PIM1 and PRISM2 did not show a significant difference with those of patients admitted during office hours. There was no significant effect of admission time on mortality in multivariate logistic regression with odds ratios of death in off-hours of 0.95 (PIM1, 95% CI 0.71-1.27, p = 0.73) and 1.03 (PRISM2, 95% CI 0.76-1.39, p = 0.82). Off-hours admission to our PICUs without 24-h in-house attendance of senior staff was not associated with higher SMRs than admission during office hours when senior staff were available in-house
Parents' experiences of care offered after stillbirth: An international online survey of high and middle-income countries
BACKGROUND: Stillbirth, the death of a baby before birth, is associated with significant psychological and social consequences that can be mitigated by respectful and supportive bereavement care. The absence of high-level evidence to support the broad scope of perinatal bereavement practices means that offering a range of options identified as valued by parents has become an important indicator of care quality. This study aimed to describe bereavement care practices offered to parents across different high-income and middle-income countries. METHODS: An online survey of parents of stillborn babies was conducted between December 2014 and February 2015. Frequencies of nine practices were compared between high-income and middle-income countries. Differences in proportions of reported practices and their associated odds ratios were calculated to compare high-income and middle-income countries. RESULTS: Over three thousand parents (3041) with a self-reported stillbirth in the preceding five years from 40 countries responded. Fifteen countries had atleast 40 responses. Significant differences in the prevalence of offering nine bereavement care practices were reported by women in high-income countries (HICs) compared with women in middle-income countries (MICs). All nine practices were reported to occur significantly more frequently by women in HICs, including opportunity to see and hold their baby (OR = 4.8, 95% CI 4.0-5.9). The widespread occurrence of all nine practices was reported only for The Netherlands. CONCLUSIONS: Bereavement care after stillbirth varies between countries. Future research should look at why these differences occur, their impact on parents, and whether differences should be addressed, particularly how to support effective communication, decision-making, and follow-up care
The emotional movie database (EMDB): a self-report and psychophysiological study
Film clips are an important tool for evoking
emotional responses in the laboratory. When compared
with other emotionally potent visual stimuli (e.g., pictures),
film clips seem to be more effective in eliciting emotions
for longer periods of time at both the subjective and
physiological levels. The main objective of the present
study was to develop a new database of affective film clips
without auditory content, based on a dimensional approach
to emotional stimuli (valence, arousal and dominance). The
study had three different phases: (1) the pre-selection and
editing of 52 film clips (2) the self-report rating of these
film clips by a sample of 113 participants and (3) psychophysiological
assessment [skin conductance level
(SCL) and the heart rate (HR)] on 32 volunteers. Film clips
from different categories were selected to elicit emotional
states from different quadrants of affective space. The
results also showed that sustained exposure to the affective
film clips resulted in a pattern of a SCL increase and HR
deceleration in high arousal conditions (i.e., horror and
erotic conditions). The resulting emotional movie database
can reliably be used in research requiring the presentation
of non-auditory film clips with different ratings of valence,
arousal and dominance.Portuguese Foundation for Science and Technology with individual grants
(SFRH/BD/41484/2007 and SFRH/BD/64355/2009
Evanescent light-matter Interactions in Atomic Cladding Wave Guides
Alkali vapors, and in particular rubidium, are being used extensively in
several important fields of research such as slow and stored light non-linear
optics3 and quantum computation. Additionally, the technology of alkali vapors
plays a major role in realizing myriad industrial applications including for
example atomic clocks magentometers8 and optical frequency stabilization.
Lately, there is a growing effort towards miniaturizing traditional
centimeter-size alkali vapor cells. Owing to the significant reduction in
device dimensions, light matter interactions are greatly enhanced, enabling new
functionalities due to the low power threshold needed for non-linear
interactions. Here, taking advantage of the mature Complimentary
Metal-Oxide-Semiconductor (CMOS) compatible platform of silicon photonics, we
construct an efficient and flexible platform for tailored light vapor
interactions on a chip. Specifically, we demonstrate light matter interactions
in an atomic cladding wave guide (ACWG), consisting of CMOS compatible silicon
nitride nano wave-guide core with a Rubidium (Rb) vapor cladding. We observe
the highly efficient interaction of the electromagnetic guided mode with the
thermal Rb cladding. The nature of such interactions is explained by a model
which predicts the transmission spectrum of the system taking into account
Doppler and transit time broadening. We show, that due to the high confinement
of the optical mode (with a mode area of 0.3{\lambda}2), the Rb absorption
saturates at powers in the nW regime.Comment: 10 Pages 4 Figures. 1 Supplementar
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