809 research outputs found
Sequences of dipole black rings and Kaluza-Klein bubbles
We construct new exact solutions to 5D Einstein-Maxwell equations describing
sequences of Kaluza-Klein bubbles and dipole black rings. The solutions are
generated by 2-soliton transformations from vacuum black ring - bubble
sequences. The properties of the solutions are investigated. We also derive the
Smarr-like relations and the mass and tension first laws in the general case
for such configurations of Kaluza-Klein bubbles and dipole black rings. The
novel moment is the appearance of the magnetic flux in the Smarr-like relations
and the first laws.Comment: 26 pages, 1 figur
Significance of herpesvirus immediate early gene expression in cellular immunity to cytomegalovirus infection
Interstitial pneumonia linked with reactivation of latent human cytomegalovirus due to iatrogenic immunosuppression can be a serious complication of bone marrow transplantation therapy of aplastic anaemia and acute leukaemia1. Cellular immunity plays a critical role in the immune surveillance of inapparent cytomegalovirus infections in man and the mouse1−7. The molecular basis of latency, however, and the interaction between latently or recurrently infected cells and the immune system of the host are poorfy understood. We have detected a so far unknown antigen in the mouse model. This antigen is found in infected cells in association with the expression of the herpesvirus 'immediate early' genes and is recognized by cytolytic T lymphocytes (CTL)8. We now demonstrate that an unexpectedly high proportion of the CTL precursors generated in vivo during acute murine cytomegalovirus infection are specific for cells that selectively synthesize immediate early proteins, indicating an immunodominant role of viral non-structural proteins
Hydrodynamics of a 5D Einstein-dilaton black hole solution and the corresponding BPS state
We apply the potential reconstruction approach to generate a series of
asymptotically AdS (aAdS) black hole solutions, with a self-interacting bulk
scalar field. Based on the method, we reproduce the pure AdS solution as a
consistency check and we also generate a simple analytic 5D black hole
solution. We then study various aspects of this solution, such as temperature,
entropy density and conserved charges. Furthermore, we study the hydrodynamics
of this black hole solution in the framework of fluid/gravity duality, e.g. the
ratio of the shear viscosity to the entropy density. In a degenerate case of
the 5D black hole solution, we find that the c function decreases monotonically
from UV to IR as expected. Finally, we investigate the stability of the
degenerate solution by studying the bosonic functional energy of the gravity
and the Witten-Nester energy . We confirm that the degenerate solution
is a BPS domain wall solution. The corresponding superpotential and the
solution of the killing spinor equation are found explicitly.Comment: V2: 23 pages, no figure, minor changes, typos corrected, new
references and comments added, version accepted by JHE
Pathologies in Asymptotically Lifshitz Spacetimes
There has been significant interest in the last several years in studying
possible gravitational duals, known as Lifshitz spacetimes, to anisotropically
scaling field theories by adding matter to distort the asymptotics of an AdS
spacetime. We point out that putative ground state for the most heavily studied
example of such a spacetime, that with a flat spatial section, suffers from a
naked singularity and further point out this singularity is not resolvable by
any known stringy effect. We review the reasons one might worry that
asymptotically Lifshitz spacetimes are unstable and employ the initial data
problem to study the stability of such systems. Rather surprisingly this
question, and even the initial value problem itself, for these spacetimes turns
out to generically not be well-posed. A generic normalizable state will evolve
in such a way to violate Lifshitz asymptotics in finite time. Conversely,
enforcing the desired asymptotics at all times puts strong restrictions not
just on the metric and fields in the asymptotic region but in the deep interior
as well. Generically, even perturbations of the matter field of compact support
are not compatible with the desired asymptotics.Comment: 36 pages, 1 figure, v2: Enhanced discussion of singularity, including
relationship to Gubser's conjecture and singularity in RG flow solution, plus
minor clarification
Charting the landscape of N=4 flux compactifications
We analyse the vacuum structure of isotropic Z_2 x Z_2 flux
compactifications, allowing for a single set of sources. Combining algebraic
geometry with supergravity techniques, we are able to classify all vacua for
both type IIA and IIB backgrounds with arbitrary gauge and geometric fluxes.
Surprisingly, geometric IIA compactifications lead to a unique theory with four
different vacua. In this case we also perform the general analysis allowing for
sources compatible with minimal supersymmetry. Moreover, some relevant examples
of type IIB non-geometric compactifications are studied. The computation of the
full N=4 mass spectrum reveals the presence of a number of non-supersymmetric
and nevertheless stable AdS_4 vacua. In addition we find a novel dS_4 solution
based on a non-semisimple gauging.Comment: Minor corrections and references added. Version published in JHE
SU(7) Unification of SU(3)_C*SU(4)_W* U(1)_{B-L}
We propose the SUSY SU(7) unification of the SU(3)_C* SU(4)_W* U(1)_{B-L}
model. Such unification scenario has rich symmetry breaking chains in a
five-dimensional orbifold. We study in detail the SUSY SU(7) symmetry breaking
into SU(3)_C* SU(4)_W* U(1)_{B-L} by boundary conditions in a Randall-Sundrum
background and its AdS/CFT interpretation. We find that successful gauge
coupling unification can be achieved in our scenario. Gauge unification favors
low left-right and unification scales with tree-level \sin^2\theta_W=0.15. We
use the AdS/CFT dual of the conformal supersymmetry breaking scenario to break
the remaining N=1 supersymmetry. We employ AdS/CFT to reproduce the NSVZ
formula and obtain the structure of the Seiberg duality in the strong coupling
region for 3/2N_c<N_F<3N_C. We show that supersymmetry is indeed broken in the
conformal supersymmetry breaking scenario with a vanishing singlet vacuum
expectation value.Comment: 25 pages, 1 figure
Exploring the equity of GP practice prescribing rates for selected coronary heart disease drugs: a multiple regression analysis with proxies of healthcare need
Background
There is a small, but growing body of literature highlighting inequities in GP practice prescribing rates for many drug therapies. The aim of this paper is to further explore the equity of prescribing for five major CHD drug groups and to explain the amount of variation in GP practice prescribing rates that can be explained by a range of healthcare needs indicators (HCNIs).
Methods
The study involved a cross-sectional secondary analysis in four primary care trusts (PCTs 1–4) in the North West of England, including 132 GP practices. Prescribing rates (average daily quantities per registered patient aged over 35 years) and HCNIs were developed for all GP practices. Analysis was undertaken using multiple linear regression.
Results
Between 22–25% of the variation in prescribing rates for statins, beta-blockers and bendrofluazide was explained in the multiple regression models. Slightly more variation was explained for ACE inhibitors (31.6%) and considerably more for aspirin (51.2%). Prescribing rates were positively associated with CHD hospital diagnoses and procedures for all drug groups other than ACE inhibitors. The proportion of patients aged 55–74 years was positively related to all prescribing rates other than aspirin, where they were positively related to the proportion of patients aged >75 years. However, prescribing rates for statins and ACE inhibitors were negatively associated with the proportion of patients aged >75 years in addition to the proportion of patients from minority ethnic groups. Prescribing rates for aspirin, bendrofluazide and all CHD drugs combined were negatively associated with deprivation.
Conclusion
Although around 25–50% of the variation in prescribing rates was explained by HCNIs, this varied markedly between PCTs and drug groups. Prescribing rates were generally characterised by both positive and negative associations with HCNIs, suggesting possible inequities in prescribing rates on the basis of ethnicity, deprivation and the proportion of patients aged over 75 years (for statins and ACE inhibitors, but not for aspirin)
Evaluating Retinal Function in Age-Related Maculopathy with the ERG Photostress Test
PURPOSE. To evaluate the diagnostic potential of the electroretinogram (ERG) photostress test and the focal cone ERG in age-related maculopathy (ARM).
METHODS. The cohort comprised 31 patients with ARM and 27 age-matched control subjects. The ERG photostress test was used to monitor cone adaptation after intense light adaptation. Focal 41- and 5-Hz cone ERGs were recorded monocularly (central 20°) to assess steady state retinal function. Univariate analysis identified electrophysiological parameters that differed between groups, and receiver operating characteristic (ROC) curves were constructed to assess their diagnostic potential. Logistic regression analysis determined the diagnostic potential of a model incorporating several independent predictors of ARM.
RESULTS. The rate of recovery of the ERG photostress test was reduced (recovery was slower) in subjects with ARM. The parameter exhibited good diagnostic potential (P = 0.002, area under ROC curve = 0.74). The implicit times of the 5-Hz (a-wave, P = 0.002; b-wave, P < 0.001) and the 41-Hz (P < 0.001) focal cone ERGs were increased, and the 41-Hz focal cone ERG amplitude (P = 0.003) and focal to full-field amplitude ratio (P = 0.001) were reduced in the ARM group. Logistic regression analysis identified three independent predictors of ARM, including the rate of recovery of the ERG photostress test.
CONCLUSIONS. Early ARM has a marked effect on the kinetics of cone adaptation. The clinical application of the ERG photostress test increases the sensitivity and specificity of a model for the diagnosis of ARM. Improved assessment of the functional integrity of the central retina will facilitate early diagnosis and evaluation of therapeutic interventions
Thermodynamics and Instabilities of a Strongly Coupled Anisotropic Plasma
We extend our analysis of a IIB supergravity solution dual to a spatially
anisotropic finite-temperature N=4 super Yang-Mills plasma. The solution is
static, possesses an anisotropic horizon, and is completely regular. The full
geometry can be viewed as a renormalization group flow from an AdS geometry in
the ultraviolet to a Lifshitz-like geometry in the infrared. The anisotropy can
be equivalently understood as resulting from a position-dependent theta-term or
from a non-zero number density of dissolved D7-branes. The holographic stress
tensor is conserved and anisotropic. The presence of a conformal anomaly plays
an important role in the thermodynamics. The phase diagram exhibits homogeneous
and inhomogeneous (i.e. mixed) phases. In some regions the homogeneous phase
displays instabilities reminiscent of those of weakly coupled plasmas. We
comment on similarities with QCD at finite baryon density and with the
phenomenon of cavitation.Comment: 62 pages, 13 figures; v2: typos fixed, added reference
Prevalence and predictors of complementary and alternative medicine use among people with coronary heart disease or at risk for this in the sixth Tromsø study: a comparative analysis using protection motivation theory
Background
Engagement in healthy lifestyle behaviors, such as healthy diet and regular physical activity, are known to reduce the risk of developing coronary heart disease (CHD). Complementary and alternative medicine (CAM) is known to be associated with having a healthy lifestyle. The primary aim of this study was to examine the prevalence and predictors of CAM use in CHD patients, and in those without CHD but at risk for developing CHD, using Protection Motivation Theory (PMT) as a guiding conceptual framework.
Method
Questionnaire data were collected from 12,981 adult participants in the cross-sectional sixth Tromsø Study (2007–8). Eligible for analyses were 11,103 participants who reported whether they had used CAM or not. Of those, 830 participants reported to have or have had CHD (CHD group), 4830 reported to have parents, children or siblings with CHD (no CHD but family risk), while 5443 reported no CHD nor family risk of CHD. We first compared the patterns of CAM use in each group, and then examined the PMT predictors of CAM use. Health vulnerability from the threat appraisal process of PMT was assessed by self-rated health and expectations for future health. Response efficacy from the coping appraisal process of PMT was assessed as preventive health beliefs and health behavior frequency.
Results
Use of CAM was most commonly seen in people with no CHD themselves, but family risk of developing CHD (35.8%), compared to people already diagnosed with CHD (30.2%) and people with no CHD nor family risk (32.1%). All four of the PMT factors; self-rated health, expectations for future health, preventive health beliefs, and the health behavior index – were predictors for CAM use in the no CHD but family risk group.
Conclusion
These findings suggest that people use CAM in response to a perceived risk of developing CHD, and to prevent disease and to maintain health
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