1,367 research outputs found
An Efficient Representation of Euclidean Gravity I
We explore how the topology of spacetime fabric is encoded into the local
structure of Riemannian metrics using the gauge theory formulation of Euclidean
gravity. In part I, we provide a rigorous mathematical foundation to prove that
a general Einstein manifold arises as the sum of SU(2)_L Yang-Mills instantons
and SU(2)_R anti-instantons where SU(2)_L and SU(2)_R are normal subgroups of
the four-dimensional Lorentz group Spin(4) = SU(2)_L x SU(2)_R. Our proof
relies only on the general properties in four dimensions: The Lorentz group
Spin(4) is isomorphic to SU(2)_L x SU(2)_R and the six-dimensional vector space
of two-forms splits canonically into the sum of three-dimensional vector spaces
of self-dual and anti-self-dual two-forms. Consolidating these two, it turns
out that the splitting of Spin(4) is deeply correlated with the decomposition
of two-forms on four-manifold which occupies a central position in the theory
of four-manifolds.Comment: 31 pages, 1 figur
Spin Calogero Particles and Bispectral Solutions of the Matrix KP Hierarchy
Pairs of matrices whose commutator differ from the identity by a
matrix of rank are used to construct bispectral differential operators with
matrix coefficients satisfying the Lax equations of the Matrix KP
hierarchy. Moreover, the bispectral involution on these operators has dynamical
significance for the spin Calogero particles system whose phase space such
pairs represent. In the case , this reproduces well-known results of
Wilson and others from the 1990's relating (spinless) Calogero-Moser systems to
the bispectrality of (scalar) differential operators. This new class of pairs
of bispectral matrix differential operators is different than
those previously studied in that acts from the left, but from the
right on a common eigenmatrix.Comment: 16 page
Individualised therapy of angiotensin converting enzyme (ACE) inhibitors in stable coronary artery disease: overview of the primary results of the PERindopril GENEtic association (PERGENE) study
In patients with stable coronary artery disease (CAD) without overt heart failure, ACE inhibitors are among the most commonly used drugs as these agents have been proven effective in reducing the risk of cardiovascular events. Considerable individual variations in the blood pressure response to ACE inhibitors are observed and as such heterogeneity in clinical treatment effect would be likely as well. Assessing the consistency of treatment benefit is essential for the rational and cost-effective prescription of ACE inhibitors. Information on heterogeneities in treatment effect between subgroups of patients could be used to develop an evidence-based guidance for the installation of ACE-inhibitor therapy. Obviously, therapy should only be applied in those patients who most likely will benefit. Attempts to develop such treatment guidance by using clinical characteristics have been unsuccessful. No heterogeneity in risk reduction by ACE inhibitors has been observed in relation to relevant clinical characteristics. A new approach to such ‘guided-therapy’ could be to integrate more patient-specific characteristics such as the patients’ genetic information. If proven feasible, pharmacogenetic profiling could optimise patients’ benefit of treatment and reduce unnecessary treatment of patients. Cardiovascular pharmacogenetic research of ACE inhibitors in coronary artery disease patients is in a formative stage and studies are limited. The PERGENE study is a large pharmacogenetic substudy of the EUROPA trial, aimed to assess the achievability of pharmacogenetic profiling. We provide an overview of the main results of the PERGENE study in terms of the genetic determinants of treatment benefit and blood pressure response. The main results of the PERGENE study show a pharmacogenetic profile related to the treatment benefit of perindopril identifying responders and non-responders to treatment
Anisotropic Drag Force from 4D Kerr-AdS Black Holes
Using AdS/CFT we investigate the effect of angular-momentum-induced
anisotropy on the instantaneous drag force of a heavy quark. The dual
description is that of a string moving in the background of a Kerr-AdS black
holes. The system exhibits the expected focussing of jets towards the impact
parameter plane. We put forward that we can use the connection between this
focussing behavior and the angular momentum induced pressure gradient to
extrapolate the pressure gradient correction to the drag force that can be used
for transverse elliptic flow in realistic RHIC. The result is recognizable as a
relativistic pressure gradient force.Comment: 22 pages and 4 figure
Fast cavity-enhanced atom detection with low noise and high fidelity
Cavity quantum electrodynamics describes the fundamental interactions between
light and matter, and how they can be controlled by shaping the local
environment. For example, optical microcavities allow high-efficiency detection
and manipulation of single atoms. In this regime fluctuations of atom number
are on the order of the mean number, which can lead to signal fluctuations in
excess of the noise on the incident probe field. Conversely, we demonstrate
that nonlinearities and multi-atom statistics can together serve to suppress
the effects of atomic fluctuations when making local density measurements on
clouds of cold atoms. We measure atom densities below 1 per cavity mode volume
near the photon shot-noise limit. This is in direct contrast to previous
experiments where fluctuations in atom number contribute significantly to the
noise. Atom detection is shown to be fast and efficient, reaching fidelities in
excess of 97% after 10 us and 99.9% after 30 us.Comment: 7 pages, 4 figures, 1 table; extensive changes to format and
discussion according to referee comments; published in Nature Communications
with open acces
Secondary Prevention of Suicide
Leo Sher and colleagues discuss recent research on interventions to prevent secondary suicide and discuss the additional research that is needed
New Horizons for Black Holes and Branes
We initiate a systematic scan of the landscape of black holes in any
spacetime dimension using the recently proposed blackfold effective worldvolume
theory. We focus primarily on asymptotically flat stationary vacuum solutions,
where we uncover large classes of new black holes. These include helical black
strings and black rings, black odd-spheres, for which the horizon is a product
of a large and a small sphere, and non-uniform black cylinders. More exotic
possibilities are also outlined. The blackfold description recovers correctly
the ultraspinning Myers-Perry black holes as ellipsoidal even-ball
configurations where the velocity field approaches the speed of light at the
boundary of the ball. Helical black ring solutions provide the first instance
of asymptotically flat black holes in more than four dimensions with a single
spatial U(1) isometry. They also imply infinite rational non-uniqueness in
ultraspinning regimes, where they maximize the entropy among all stationary
single-horizon solutions. Moreover, static blackfolds are possible with the
geometry of minimal surfaces. The absence of compact embedded minimal surfaces
in Euclidean space is consistent with the uniqueness theorem of static black
holes.Comment: 54 pages, 7 figures; v2 added references, added comments in the
subsection discussing the physical properties of helical black rings; v3
added references, fixed minor typo
Can We Really Prevent Suicide?
Every year, suicide is among the top 20 leading causes of death globally for all ages. Unfortunately, suicide is difficult to prevent, in large part because the prevalence of risk factors is high among the general population. In this review, clinical and psychological risk factors are examined and methods for suicide prevention are discussed. Prevention strategies found to be effective in suicide prevention
include means restriction, responsible media coverage, and general public education, as well identification methods such as screening, gatekeeper training, and primary care physician education. Although the treatment for preventing suicide is difficult, follow-up that includes pharmacotherapy, psychotherapy, or both may be useful. However, prevention methods cannot be restricted to the individual. Community, social, and policy interventions will also be essentia
Preventing recurrence of thromboembolic events through coordinated treatment in the District of Columbia
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/87024/1/j.1747-4949.2011.00654.x.pd
AdS_3/LCFT_2 - Correlators in Cosmological Topologically Massive Gravity
For cosmological topologically massive gravity at the chiral point we
calculate momentum space 2- and 3-point correlators of operators in the
postulated dual CFT on the cylinder. These operators are sourced by the bulk
and boundary gravitons. Our correlators are fully consistent with the proposal
that cosmological topologically massive gravity at the chiral point is dual to
a logarithmic CFT. In the process we give a complete classification of
normalizable and non-normalizeable left, right and logarithmic solutions to the
linearized equations of motion in global AdS_3.Comment: 39 pages + appendices, 1 eps figure, v2: minor changes in text in
4.1.2, corrected typo in (2.31
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