265 research outputs found
Novelâand âNeuââTherapeutic Possibilities for Heart FailureââEditorials published in the Journal of the American College of Cardiologyreflect the views of the authors and do not necessarily represent the views of JACCor the American College of Cardiology.
Intersecting D3-branes and Holography
We study a defect conformal field theory describing D3-branes intersecting
over two space-time dimensions. This theory admits an exact Lagrangian
description which includes both two- and four-dimensional degrees of freedom,
has (4,4) supersymmetry and is invariant under global conformal
transformations. Both two- and four-dimensional contributions to the action are
conveniently obtained in a two-dimensional (2,2) superspace. In a suitable
limit, the theory has a dual description in terms of a probe D3-brane wrapping
an AdS_3 x S^1 slice of AdS_5 x S^5. We consider the AdS/CFT dictionary for
this set-up. In particular we find classical probe fluctuations corresponding
to the holomorphic curve wy=c\alpha^{\prime}. These fluctuations are dual to
defect fields containing massless two-dimensional scalars which parameterize
the classical Higgs branch, but do not correspond to states in the Hilbert
space of the CFT. We also identify probe fluctuations which are dual to BPS
superconformal primary operators and to their descendants. A
non-renormalization theorem is conjectured for the correlators of these
operators, and verified to order g^2.Comment: 46 pages, 5 figures, Latex, minor corrections to section 4.2, version
published in Phys. Rev.
Near-Ultraviolet Properties of a Large Sample of Type Ia Supernovae as Observed with the Swift UVOT
We present ultraviolet (UV) and optical photometry of 26 Type Ia supernovae
(SNe~Ia) observed from March 2005 to March 2008 with the NASA {\it Swift}
Ultraviolet and Optical Telescope (UVOT). The dataset consists of 2133
individual observations, making it by far the most complete study of the UV
emission from SNe~Ia to date. Grouping the SNe into three subclasses as derived
from optical observations, we investigate the evolution of the colors of these
SNe, finding a high degree of homogeneity within the normal subclass, but
dramatic differences between that group and the subluminous and SN 2002cx-like
groups. For the normal events, the redder UV filters on UVOT (, ) show
more homogeneity than do the bluer UV filters (, ). Searching for
purely UV characteristics to determine existing optically based groupings, we
find the peak width to be a poor discriminant, but we do see a variation in the
time delay between peak emission and the late, flat phase of the light curves.
The UV light curves peak a few days before the band for most subclasses (as
was previously reported by Jha et al. 2006a), although the SN 2002cx-like
objects peak at a very early epoch in the UV. That group also features the
bluest emission observed among SNe~Ia. As the observational campaign is
ongoing, we discuss the critical times to observe, as determined by this study,
in order to maximize the scientific output of future observations.Comment: Accepted to Astrophysical Journa
A multi-stage genome-wide association study of bladder cancer identifies multiple susceptibility loci.
We conducted a multi-stage, genome-wide association study of bladder cancer with a primary scan of 591,637 SNPs in 3,532 affected individuals (cases) and 5,120 controls of European descent from five studies followed by a replication strategy, which included 8,382 cases and 48,275 controls from 16 studies. In a combined analysis, we identified three new regions associated with bladder cancer on chromosomes 22q13.1, 19q12 and 2q37.1: rs1014971, (P = 8 Ă 10â»ÂčÂČ) maps to a non-genic region of chromosome 22q13.1, rs8102137 (P = 2 Ă 10â»ÂčÂč) on 19q12 maps to CCNE1 and rs11892031 (P = 1 Ă 10â»â·) maps to the UGT1A cluster on 2q37.1. We confirmed four previously identified genome-wide associations on chromosomes 3q28, 4p16.3, 8q24.21 and 8q24.3, validated previous candidate associations for the GSTM1 deletion (P = 4 Ă 10â»ÂčÂč) and a tag SNP for NAT2 acetylation status (P = 4 Ă 10â»ÂčÂč), and found interactions with smoking in both regions. Our findings on common variants associated with bladder cancer risk should provide new insights into the mechanisms of carcinogenesis
Hospital variation in transfusion and infection after cardiac surgery: a cohort study
<p>Abstract</p> <p>Background</p> <p>Transfusion practices in hospitalised patients are being re-evaluated, in part due to studies indicating adverse effects in patients receiving large quantities of stored blood. Concomitant with this re-examination have been reports showing variability in the use of specific blood components. This investigation was designed to assess hospital variation in blood use and outcomes in cardiac surgery patients.</p> <p>Methods</p> <p>We evaluated outcomes in 24,789 Medicare beneficiaries in the state of Michigan, USA who received coronary artery bypass graft surgery from 2003 to 2006. Using a cohort design, patients were followed from hospital admission to assess transfusions, in-hospital infection and mortality, as well as hospital readmission and mortality 30 days after discharge. Multilevel mixed-effects logistic regression was used to calculate the intrahospital correlation coefficient (for 40 hospitals) and compare outcomes by transfusion status.</p> <p>Results</p> <p>Overall, 30% (95 CI, 20% to 42%) of the variance in transfusion practices was attributable to hospital site. Allogeneic blood use by hospital ranged from 72.5% to 100% in women and 49.7% to 100% in men. Allogeneic, but not autologous, blood transfusion increased the odds of in-hospital infection 2.0-fold (95% CI 1.6 to 2.5), in-hospital mortality 4.7-fold (95% CI 2.4 to 9.2), 30-day readmission 1.4-fold (95% CI 1.2 to 1.6), and 30-day mortality 2.9-fold (95% CI 1.4 to 6.0) in elective surgeries. Allogeneic transfusion was associated with infections of the genitourinary system, respiratory tract, bloodstream, digestive tract and skin, as well as infection with <it>Clostridium difficile</it>. For each 1% increase in hospital transfusion rates, there was a 0.13% increase in predicted infection rates.</p> <p>Conclusion</p> <p>Allogeneic blood transfusion was associated with an increased risk of infection at multiple sites, suggesting a system-wide immune response. Hospital variation in transfusion practices after coronary artery bypass grafting was considerable, indicating that quality efforts may be able to influence practice and improve outcomes.</p
Cosmological parameters from CMB and other data: a Monte-Carlo approach
We present a fast Markov Chain Monte-Carlo exploration of cosmological
parameter space. We perform a joint analysis of results from recent CMB
experiments and provide parameter constraints, including sigma_8, from the CMB
independent of other data. We next combine data from the CMB, HST Key Project,
2dF galaxy redshift survey, supernovae Ia and big-bang nucleosynthesis. The
Monte Carlo method allows the rapid investigation of a large number of
parameters, and we present results from 6 and 9 parameter analyses of flat
models, and an 11 parameter analysis of non-flat models. Our results include
constraints on the neutrino mass (m_nu < 0.3eV), equation of state of the dark
energy, and the tensor amplitude, as well as demonstrating the effect of
additional parameters on the base parameter constraints. In a series of
appendices we describe the many uses of importance sampling, including
computing results from new data and accuracy correction of results generated
from an approximate method. We also discuss the different ways of converting
parameter samples to parameter constraints, the effect of the prior, assess the
goodness of fit and consistency, and describe the use of analytic
marginalization over normalization parameters.Comment: Quintessence results now include perturbations. Changes to match
version accepted by PRD. MCMC code and data are available at
http://cosmologist.info/cosmomc/ along with a B&W printer-friendly version of
the pape
Cosmic microwave anisotropies from BPS semilocal strings
We present the first ever calculation of cosmic microwave background CMB
anisotropy power spectra from semilocal cosmic strings, obtained via
simulations of a classical field theory. Semilocal strings are a type of
non-topological defect arising in some models of inflation motivated by
fundamental physics, and are thought to relax the constraints on the symmetry
breaking scale as compared to models with (topological) cosmic strings. We
derive constraints on the model parameters, including the string tension
parameter mu, from fits to cosmological data, and find that in this regard BPS
semilocal strings resemble global textures more than topological strings. The
observed microwave anisotropy at l = 10 is reproduced if Gmu = 5.3x10^{-6} (G
is Newton's constant). However as with other defects the spectral shape does
not match observations, and in models with inflationary perturbations plus
semilocal strings the 95% confidence level upper bound is Gmu<2.0x10^{-6} when
CMB data, Hubble Key Project and Big Bang Nucleosynthesis data are used (c.f.
Gmu<0.9x10^{-6} for cosmic strings). We additionally carry out a Bayesian model
comparison of several models with and without defects, showing models with
defects are neither conclusively favoured nor disfavoured at present.Comment: 15 pages, 13 figures. Minor correction of numerical results, matches
published versio
Predicting Hemolytic Uremic Syndrome and Renal Replacement Therapy in Shiga Toxin-producing Escherichia coli-infected Children.
BACKGROUND: Shiga toxin-producing Escherichia coli (STEC) infections are leading causes of pediatric acute renal failure. Identifying hemolytic uremic syndrome (HUS) risk factors is needed to guide care.
METHODS: We conducted a multicenter, historical cohort study to identify features associated with development of HUS (primary outcome) and need for renal replacement therapy (RRT) (secondary outcome) in STEC-infected children without HUS at initial presentation. Children agedeligible.
RESULTS: Of 927 STEC-infected children, 41 (4.4%) had HUS at presentation; of the remaining 886, 126 (14.2%) developed HUS. Predictors (all shown as odds ratio [OR] with 95% confidence interval [CI]) of HUS included younger age (0.77 [.69-.85] per year), leukocyte count â„13.0 Ă 103/ÎŒL (2.54 [1.42-4.54]), higher hematocrit (1.83 [1.21-2.77] per 5% increase) and serum creatinine (10.82 [1.49-78.69] per 1 mg/dL increase), platelet count \u3c250 \u3eĂ 103/ÎŒL (1.92 [1.02-3.60]), lower serum sodium (1.12 [1.02-1.23 per 1 mmol/L decrease), and intravenous fluid administration initiated â„4 days following diarrhea onset (2.50 [1.14-5.46]). A longer interval from diarrhea onset to index visit was associated with reduced HUS risk (OR, 0.70 [95% CI, .54-.90]). RRT predictors (all shown as OR [95% CI]) included female sex (2.27 [1.14-4.50]), younger age (0.83 [.74-.92] per year), lower serum sodium (1.15 [1.04-1.27] per mmol/L decrease), higher leukocyte count â„13.0 Ă 103/ÎŒL (2.35 [1.17-4.72]) and creatinine (7.75 [1.20-50.16] per 1 mg/dL increase) concentrations, and initial intravenous fluid administration â„4 days following diarrhea onset (2.71 [1.18-6.21]).
CONCLUSIONS: The complex nature of STEC infection renders predicting its course a challenge. Risk factors we identified highlight the importance of avoiding dehydration and performing close clinical and laboratory monitoring
Proof of impact and pipeline planning: directions and challenges for social audit in the health sector
Social audits are typically observational studies, combining qualitative and quantitative uptake of evidence with consultative interpretation of results. This often falters on issues of causality because their cross-sectional design limits interpretation of time relations and separation out of other indirect associations
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