2,646 research outputs found
NUT-Charged Black Holes in Gauss-Bonnet Gravity
We investigate the existence of Taub-NUT/bolt solutions in Gauss-Bonnet
gravity and obtain the general form of these solutions in dimensions. We
find that for all non-extremal NUT solutions of Einstein gravity having no
curvature singularity at , there exist NUT solutions in Gauss-Bonnet
gravity that contain these solutions in the limit that the Gauss-Bonnet
parameter goes to zero. Furthermore there are no NUT solutions in
Gauss-Bonnet gravity that yield non-extremal NUT solutions to Einstein gravity
having a curvature singularity at in the limit . Indeed,
we have non-extreme NUT solutions in dimensions with non-trivial
fibration only when the -dimensional base space is chosen to be
. We also find that the Gauss-Bonnet gravity has extremal NUT
solutions whenever the base space is a product of 2-torii with at most a
2-dimensional factor space of positive curvature. Indeed, when the base space
has at most one positively curved two dimensional space as one of its factor
spaces, then Gauss-Bonnet gravity admits extreme NUT solutions, even though
there a curvature singularity exists at . We also find that one can have
bolt solutions in Gauss-Bonnet gravity with any base space with factor spaces
of zero or positive constant curvature. The only case for which one does not
have bolt solutions is in the absence of a cosmological term with zero
curvature base space.Comment: 20 pages, referrence added, a few typos correcte
Localizing gravity on exotic thick 3-branes
We consider localization of gravity on thick branes with a non trivial
structure. Double walls that generalize the thick Randall-Sundrum solution, and
asymmetric walls that arise from a Z_2-symmetric scalar potential, are
considered. We present a new asymmetric solution: a thick brane interpolating
between two AdS_5 spacetimes with different cosmological constants, which can
be derived from a ``fake supergravity'' superpotential, and show that it is
possible to confine gravity on such branes.Comment: Final version, minor changes, references adde
An integrated care pathway for menorrhagia across the primary–secondary interface : patients' experience, clinical outcomes, and service utilisation
Background: ‘‘Referral’’ characterises a significant area of interaction between primary and secondary care.
Despite advantages, it can be inflexible, and may lead to duplication.
Objective: To examine the outcomes of an integrated model that lends weight to general practitioner (GP)-led
evidence based care.
Design: A prospective, non-random comparison of two services: women attending the new (Bridges) pathway
compared with those attending a consultant-led one-stop menstrual clinic (OSMC). Patients’ views were
examined using patient career diaries, health and clinical outcomes, and resource utilisation. Follow-up was
for 8 months.
Setting: A large teaching hospital and general practices within one primary care trust (PCT).
Results: Between March 2002 and June 2004, 99 women in the Bridges pathway were compared with 94
women referred to the OSMC by GPs from non-participating PCTs. The patient career diary demonstrated a
significant improvement in the Bridges group for patient information, fitting in at the point of arrangements
made for the patient to attend hospital (ease of access) (p,0.001), choice of doctor (p = 0.020), waiting time
for an appointment (p,0.001), and less ‘‘limbo’’ (patient experience of non-coordination between primary
and secondary care) (p,0.001). At 8 months there were no significant differences between the two groups in
surgical and medical treatment rates or in the use of GP clinic appointments. Significantly fewer (traditional)
hospital outpatient appointments were made in the Bridges group than in the OSMC group (p,0.001).
Conclusion: A general practice-led model of integrated care can significantly reduce outpatient attendance
while improving patient experience, and maintaining the quality of care
Taub-NUT/Bolt Black Holes in Gauss-Bonnet-Maxwell Gravity
We present a class of higher dimensional solutions to Gauss-Bonnet-Maxwell
equations in dimensions with a U(1) fibration over a -dimensional
base space . These solutions depend on two extra parameters, other
than the mass and the NUT charge, which are the electric charge and the
electric potential at infinity . We find that the form of metric is
sensitive to geometry of the base space, while the form of electromagnetic
field is independent of . We investigate the existence of
Taub-NUT/bolt solutions and find that in addition to the two conditions of
uncharged NUT solutions, there exist two other conditions. These two extra
conditions come from the regularity of vector potential at and the fact
that the horizon at should be the outer horizon of the black hole. We
find that for all non-extremal NUT solutions of Einstein gravity having no
curvature singularity at , there exist NUT solutions in
Gauss-Bonnet-Maxwell gravity. Indeed, we have non-extreme NUT solutions in
dimensions only when the -dimensional base space is chosen to be
. We also find that the Gauss-Bonnet-Maxwell gravity has
extremal NUT solutions whenever the base space is a product of 2-torii with at
most a 2-dimensional factor space of positive curvature, even though there a
curvature singularity exists at . We also find that one can have bolt
solutions in Gauss-Bonnet-Maxwell gravity with any base space. The only case
for which one does not have black hole solutions is in the absence of a
cosmological term with zero curvature base space.Comment: 23 pages, 3 figures, typos fixed, a few references adde
Role of neuropeptides, hormones, and growth factors in regulating thymopoiesis in middle to old age
The deterioration in adaptive immunity and T-lymphocyte output and the narrowing of the T cell receptor repertoire with age are largely attributable to thymic involution. The loss of thymic function with age may be due to diminished numbers of early thymic progenitors and epithelial cells, and the loss of critical tropic factors within the thymic microenvironment. Here we review some of the recent literature demonstrating a role for neuropeptides, hormones, and growth factors that can influence thymopoiesis associated with stress and aging
qPrimerDepot: a primer database for quantitative real time PCR
Gene expression studies employing high throughput real time PCR methods require finding uniform conditions for optimal amplification of multiple targets, often a daunting task. We developed a primer database, qPrimerDepot, which provides optimized primers for all human and mouse RefSeq genes. These primers are designed to amplify desired templates under unified annealing temperature. For most intron-bearing genes, primers flank one of the largest introns thus minimizing background noise due to genomic DNA contamination. The qPrimerDepot database can be accessed at and
Relativistic Acoustic Geometry
Sound wave propagation in a relativistic perfect fluid with a non-homogeneous
isentropic flow is studied in terms of acoustic geometry. The sound wave
equation turns out to be equivalent to the equation of motion for a massless
scalar field propagating in a curved space-time geometry. The geometry is
described by the acoustic metric tensor that depends locally on the equation of
state and the four-velocity of the fluid. For a relativistic supersonic flow in
curved space-time the ergosphere and acoustic horizon may be defined in a way
analogous the non-relativistic case. A general-relativistic expression for the
acoustic analog of surface gravity has been found.Comment: 14 pages, LaTe
Applying the National Health Educator Competencies Update Project Model to Health Education
A brief overview of the six-year National Health Educator Competencies Update Project (CUP) research is provided as an introduction to a discussion of applications of the resulting CUP Hierarchical Model. Considerations for application of the model to the professional preparation, credentialing and professional development of health educators are explored. In addition, examples of the applicability of the CUP Hierarchical Model to three different work settings are presented at the Entry, Advanced 1, and Advanced 2 levels of professional practice. The benefits of being guided by a validated practice model are discussed with implications for future research endeavors
Colliding axisymmetric pp-waves
An exact solution is found describing the collision of axisymmetric pp-waves
with M=0. They are impulsive in character and their coordinate singularities
become point curvature singularities at the boundaries of the interaction
region. The solution is conformally flat. Concrete examples are given,
involving an ultrarelativistic black hole against a burst of pure radiation or
two colliding beam- like waves.Comment: 6 pages, REVTeX, some misprints are correcte
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