Magnetic Field Evolution in Merging Clusters of Galaxies

We present initial results from the first 3-dimensional numerical magnetohydrodynamical (MHD) simulations of magnetic field evolution in merging clusters of galaxies. Within the framework of idealized initial conditions similar to our previous work, we look at the gasdynamics and the magnetic field evolution during a major merger event in order to examine the suggestion that shocks and turbulence generated during a cluster/subcluster merger can produce magnetic field amplification and relativistic particle acceleration and, as such, may play a role in the formation and evolution of cluster-wide radio halos. The ICM, as represented by the equations of ideal MHD, is evolved self-consistently within a changing gravitational potential defined largely by the collisionless dark matter component represented by an N-body particle distribution. The MHD equations are solved by the Eulerian, finite-difference code, ZEUS. The particles are evolved by a standard particle-mesh (PM) code. We find significant evolution of the magnetic field structure and strength during two distinct epochs of the merger evolution.Comment: 21 pages, 7 figures, Figure 2 is color postscript. Accepted for publication in Ap

Thoracic endovascular aneurysm repair, race, and volume in thoracic aneurysm repair

BackgroundVolume-based disparities in surgical care are often associated with poorer results in African American patients. We examined the effect of treatment patterns and outcomes, by race, for isolated thoracic aortic aneurysm (TAA).MethodsUsing Medicare claims (1999-2007), we studied all patients undergoing repair of TAAs, via open surgery or thoracic endovascular aneurysm repair (TEVAR). We studied 30-day mortality and complications by race, procedure type, and hospital volume.ResultsWe studied 12,573 patients who underwent open TAA repair (4% of whom were black) and 2732 patients who underwent TEVAR (8% of whom were black). In open repair, black patients had higher 30-day mortality than white patients (18% vs 10%; P < .001), while mortality rates were similar with TEVAR (8% black vs 9% white; P = .56). For open repair, black patients were more likely to undergo surgery at low-volume hospitals, where overall operative mortality was highest (14% at very low-volume hospitals, 7% at very high-volume hospitals; P < .001). However, for TEVAR, black patients were not more likely to undergo repair at low-volume hospitals, and mortality differences were not evident across volume strata (9% at very low-volume hospitals, 7% at very high-volume hospitals; P = .328). Multivariable analyses adjusting for age, sex, race, comorbidity, and volume confirmed that increased perioperative mortality was associated with black race for open surgery (OR, 2.0, 95% CI, 1.5-2.5; P < .001) but not TEVAR (OR, 0.9, 95% CI, 0.6-1.5; P = .721).ConclusionsWhile racial disparities in surgical care have a significant effect on mortality with open thoracoabdominal aortic aneurysm repair, black patients undergoing TEVAR obtain similar outcomes as white patients. New technology can limit the effect of racial disparities in surgical care

Global systematic review and ecological analysis of HIV in people who inject drugs:National population sizes and factors associated with HIV prevalence

Background People who inject drugs (PWID) are at elevated risk of HIV infection. Data on population sizes of PWID living with HIV are needed to inform the implementation of prevention, treatment and care programs. We estimated national population sizes of people who recently (past 12 months) injected drugs living with HIV and evaluated ecological associations with HIV prevalence in PWID. Methods We used national data on the prevalence of injecting drug use and of HIV among PWID, derived from systematic reviews, to estimate national population sizes of PWID living with HIV. Uncertainty was estimated using Monte Carlo simulation with 100,000 draws. We extracted data on sample characteristics from studies of HIV prevalence among PWID, and identified national indicators that have been observed or hypothesised to be associated with HIV prevalence in PWID. We used linear regression to evaluate associations between these variables and HIV prevalence in PWID. Results Four countries comprised 55% of the estimated global population of PWID living with HIV: Russia (572,500; 95% uncertainty interval (UI) 235,500–1,036,500); Brazil (462,000; 95% UI 283,500–674,500); China (316,500; 95% UI 171,500–493,500), and the United States (195,500; 95% UI 80,000–343,000). Greater anti-HCV prevalence and national income inequality were associated with greater HIV prevalence in PWID. Conclusion The countries with the largest populations of PWID living with HIV will need to dramatically scale up prevention, treatment and care interventions to prevent further increases in population size. The association between anti-HCV prevalence and HIV prevalence among PWID corroborates findings that settings with increasing HCV should implement effective interventions to prevent HIV outbreaks. The association between income inequality and HIV among PWID reinforces the need to implement structural interventions alongside targeted individual-level strategies

Homozygosity for a missense mutation in the 67 kDa isoform of glutamate decarboxylase in a family with autosomal recessive spastic cerebral palsy: parallels with Stiff-Person Syndrome and other movement disorders

Background Cerebral palsy (CP) is an heterogeneous group of neurological disorders of movement and/or posture, with an estimated incidence of 1 in 1000 live births. Non-progressive forms of symmetrical, spastic CP have been identified, which show a Mendelian autosomal recessive pattern of inheritance. We recently described the mapping of a recessive spastic CP locus to a 5 cM chromosomal region located at 2q24-31.1, in rare consanguineous families. Methods Here we present data that refine this locus to a 0.5 cM region, flanked by the microsatellite markers D2S2345 and D2S326. The minimal region contains the candidate gene GAD1, which encodes a glutamate decarboxylase isoform (GAD67), involved in conversion of the amino acid and excitatory neurotransmitter glutamate to the inhibitory neurotransmitter γ-aminobutyric acid (GABA). Results A novel amino acid mis-sense mutation in GAD67 was detected, which segregated with CP in affected individuals. Conclusions This result is interesting because auto-antibodies to GAD67 and the more widely studied GAD65 homologue encoded by the GAD2 gene, are described in patients with Stiff-Person Syndrome (SPS), epilepsy, cerebellar ataxia and Batten disease. Further investigation seems merited of the possibility that variation in the GAD1 sequence, potentially affecting glutamate/GABA ratios, may underlie this form of spastic CP, given the presence of anti-GAD antibodies in SPS and the recognised excitotoxicity of glutamate in various contexts

Complexity in the genetic architecture of leukoaraiosis in hypertensive sibships from the GENOA Study

<p>Abstract</p> <p>Background</p> <p>Subcortical white matter hyperintensity on magnetic resonance imaging (MRI) of the brain, referred to as leukoaraiosis, is associated with increased risk of stroke and dementia. Hypertension may contribute to leukoaraiosis by accelerating the process of arteriosclerosis involving penetrating small arteries and arterioles in the brain. Leukoaraiosis volume is highly heritable but shows significant inter-individual variability that is not predicted well by any clinical covariates (except for age) or by single SNPs.</p> <p>Methods</p> <p>As part of the Genetics of Microangiopathic Brain Injury (GMBI) Study, 777 individuals (74% hypertensive) underwent brain MRI and were genotyped for 1649 SNPs from genes known or hypothesized to be involved in arteriosclerosis and related pathways. We examined SNP main effects, epistatic (gene-gene) interactions, and context-dependent (gene-environment) interactions between these SNPs and covariates (including conventional and novel risk factors for arteriosclerosis) for association with leukoaraiosis volume. Three methods were used to reduce the chance of false positive associations: 1) false discovery rate (FDR) adjustment for multiple testing, 2) an internal replication design, and 3) a ten-iteration four-fold cross-validation scheme.</p> <p>Results</p> <p>Four SNP main effects (in <it>F3</it>, <it>KITLG</it>, <it>CAPN10</it>, and <it>MMP2</it>), 12 SNP-covariate interactions (including interactions between <it>KITLG </it>and homocysteine, and between <it>TGFB3 </it>and both physical activity and C-reactive protein), and 173 SNP-SNP interactions were significant, replicated, and cross-validated. While a model containing the top single SNPs with main effects predicted only 3.72% of variation in leukoaraiosis in independent test samples, a multiple variable model that included the four most highly predictive SNP-SNP and SNP-covariate interactions predicted 11.83%.</p> <p>Conclusion</p> <p>These results indicate that the genetic architecture of leukoaraiosis is complex, yet predictive, when the contributions of SNP main effects are considered in combination with effects of SNP interactions with other genes and covariates.</p

Photometric and Spectroscopic Observations of SN 1990E in NGC 1035: Observational Constraints for Models of Type II Supernovae

We present 126 photometric and 30 spectral observation of SN 1990E spanning from 12 days before B maximum to 600 days past discovery. These observations show that SN 1990E was of type II-P, displaying hydrogen in its spectrum, and the characteristic plateau in its light curve. SN 1990E is one of the few SNe II which has been well observed before maximum light, and we present evidence that this SN was discovered very soon after its explosion. In the earliest spectra we identify, for the first time, several N II lines. We present a new technique for measuring extinction to SNe II based on the evolution of absorption lines, and use this method to estimate the extinction to SN 1990E, Av=1.5+/-0.3 mag. From our photometric data we have constructed a bolometric light curve for SN 1990E and show that, even at the earliest times, the bolometric luminosity was falling rapidly. We use the late-time bolometric light curve to show that SN 1990E trapped a majority of the gamma rays produced by the radioactive decay of 56Co, and estimate that SN 1990E ejected 0.073 Mo of 56Ni, an amount virtually identical to that of SN 1987A. [excerpt

The Long-Baseline Neutrino Experiment: Exploring Fundamental Symmetries of the Universe

The preponderance of matter over antimatter in the early Universe, the dynamics of the supernova bursts that produced the heavy elements necessary for life and whether protons eventually decay --- these mysteries at the forefront of particle physics and astrophysics are key to understanding the early evolution of our Universe, its current state and its eventual fate. The Long-Baseline Neutrino Experiment (LBNE) represents an extensively developed plan for a world-class experiment dedicated to addressing these questions. LBNE is conceived around three central components: (1) a new, high-intensity neutrino source generated from a megawatt-class proton accelerator at Fermi National Accelerator Laboratory, (2) a near neutrino detector just downstream of the source, and (3) a massive liquid argon time-projection chamber deployed as a far detector deep underground at the Sanford Underground Research Facility. This facility, located at the site of the former Homestake Mine in Lead, South Dakota, is approximately 1,300 km from the neutrino source at Fermilab -- a distance (baseline) that delivers optimal sensitivity to neutrino charge-parity symmetry violation and mass ordering effects. This ambitious yet cost-effective design incorporates scalability and flexibility and can accommodate a variety of upgrades and contributions. With its exceptional combination of experimental configuration, technical capabilities, and potential for transformative discoveries, LBNE promises to be a vital facility for the field of particle physics worldwide, providing physicists from around the globe with opportunities to collaborate in a twenty to thirty year program of exciting science. In this document we provide a comprehensive overview of LBNE's scientific objectives, its place in the landscape of neutrino physics worldwide, the technologies it will incorporate and the capabilities it will possess.Comment: Major update of previous version. This is the reference document for LBNE science program and current status. Chapters 1, 3, and 9 provide a comprehensive overview of LBNE's scientific objectives, its place in the landscape of neutrino physics worldwide, the technologies it will incorporate and the capabilities it will possess. 288 pages, 116 figure