Chandra ACIS Survey of M33 (ChASeM33): The enigmatic X-ray emission from IC131

We present the first X-ray analysis of the diffuse hot ionized gas and the point sources in IC131, after NGC604 the second most X-ray luminous giant HII region in M33. The X-ray emission is detected only in the south eastern part of IC131 (named IC131-se) and is limited to an elliptical region of ~200pc in extent. This region appears to be confined towards the west by a hemispherical shell of warm ionized gas and only fills about half that volume. Although the corresponding X-ray spectrum has 1215 counts, it cannot conclusively be told whether the extended X-ray emission is thermal, non-thermal, or a combination of both. A thermal plasma model of kT_e=4.3keV or a single power law of Gamma=2.1 fit the spectrum equally well. If the spectrum is purely thermal (non-thermal), the total unabsorbed X-ray luminosity in the 0.35-8keV energy band amounts to L_X = 6.8(8.7)x10^35erg/s. Among other known HII regions IC131-se seems to be extreme regarding the combination of its large extent of the X-ray plasma, the lack of massive O stars, its unusually high electron temperature (if thermal), and the large fraction of L_X emitted above 2keV (~40-53%). A thermal plasma of ~4keV poses serious challenges to theoretical models, as it is not clear how high electron temperatures can be produced in HII regions in view of mass-proportional and collisionless heating. If the gas is non-thermal or has non-thermal contributions, synchrotron emission would clearly dominate over inverse Compton emission. It is not clear if the same mechanisms which create non-thermal X-rays or accelerate CRs in SNRs can be applied to much larger scales of 200pc. In both cases the existing theoretical models for giant HII regions and superbubbles do not explain the hardness and extent of the X-ray emission in IC131-se.Comment: 28 pages, 7 figures and 2 tables. Accepted for publication in ApJ. For a high resolution version of the paper see http://hea-www.harvard.edu/vlp_m33_public/publications.htm

Chandra ACIS Survey of M33 (ChASeM33): A First Look

We present an overview of the Chandra ACIS Survey of M33 (ChASeM33): A Deep Survey of the Nearest Face-on Spiral Galaxy. The 1.4 Ms survey covers the galaxy out to R \approx 18\arcmin (\approx 4 kpc). These data provide the most intensive, high spatial resolution assessment of the X-ray source populations available for the confused inner regions of M33. Mosaic images of the ChASeM33 observations show several hundred individual X-ray sources as well as soft diffuse emission from the hot interstellar medium. Bright, extended emission surrounds the nucleus and is also seen from the giant \hii regions NGC 604 and IC 131. Fainter extended emission and numerous individual sources appear to trace the inner spiral structure. The initial source catalog, arising from $\sim$~2/3 of the expected survey data, includes 394 sources significant at the $3\sigma$ confidence level or greater, down to a limiting luminosity (absorbed) of $\sim$1.6\ergs{35} (0.35 -- 8.0 keV). The hardness ratios of the sources separate those with soft, thermal spectra such as supernova remnants from those with hard, non-thermal spectra such as X-ray binaries and background active galactic nuclei. Emission extended beyond the Chandra point spread function is evident in 23 of the 394 sources. Cross-correlation of the ChASeM33 sources against previous catalogs of X-ray sources in M33 results in matches for the vast majority of the brighter sources and shows 28 ChASeM33 sources within 10\arcsec of supernova remnants identified by prior optical and radio searches. This brings the total number of such associations to 31 out of 100 known supernova remnants in M33.Comment: accepted for publication ApJS, full resolution images and complete tables available at http://hea-www.harvard.edu/vlp_m33_public

SN 2010jl: Optical to Hard X-ray Observations Reveal an Explosion Embedded In a Ten Solar Mass Cocoon

Some supernovae (SNe) may be powered by the interaction of the SN ejecta with a large amount of circumstellar matter (CSM). However, quantitative estimates of the CSM mass around such SNe are missing when the CSM material is optically thick. Specifically, current estimators are sensitive to uncertainties regarding the CSM density profile and the ejecta velocity. Here we outline a method to measure the mass of the optically thick CSM around such SNe. We present new visible-light and X-ray observations of SN 2010jl (PTF 10aaxf), including the first detection of an SN in the hard X-ray band using NuSTAR. The total radiated luminosity of SN 2010jl is extreme—at least 9 × 1050 erg. By modeling the visible-light data, we robustly show that the mass of the circumstellar material within ~1016 cm of the progenitor of SN 2010jl was in excess of 10 M☉. This mass was likely ejected tens of years prior to the SN explosion. Our modeling suggests that the shock velocity during shock breakout was ~6000 km s–1, decelerating to ~2600 km s–1 about 2 yr after maximum light. Furthermore, our late-time NuSTAR and XMM spectra of the SN presumably provide the first direct measurement of SN shock velocity 2 yr after the SN maximum light—measured to be in the range of 2000-4500 km s–1 if the ions and electrons are in equilibrium, and ≳2000 km s–1 if they are not in equilibrium. This measurement is in agreement with the shock velocity predicted by our modeling of the visible-light data. Our observations also show that the average radial density distribution of the CSM roughly follows an r–2 law. A possible explanation for the ≳10 M☉ of CSM and the wind-like profile is that they are the result of multiple pulsational pair instability events prior to the SN explosion, separated from each other by years

Real-Time Reverse Transcription–Polymerase Chain Reaction Assay for SARS-associated Coronavirus

A real-time reverse transcription–polymerase chain reaction (RT-PCR) assay was developed to rapidly detect the severe acute respiratory syndrome–associated coronavirus (SARS-CoV). The assay, based on multiple primer and probe sets located in different regions of the SARS-CoV genome, could discriminate SARS-CoV from other human and animal coronaviruses with a potential detection limit of <10 genomic copies per reaction. The real-time RT-PCR assay was more sensitive than a conventional RT-PCR assay or culture isolation and proved suitable to detect SARS-CoV in clinical specimens. Application of this assay will aid in diagnosing SARS-CoV infection

Vitamin D and Foot and Ankle Trauma: An individual or societal problem?

Background Vitamin D deficiency is a worldwide health concern. Hypovitaminosis D may adversely affect recovery from bone injury. The authors aimed to perform an audit of the Vitamin D status of patients in three centres in the United Kingdom presenting with foot and ankle osseous damage. Methods Serum 25-hydroxyvitamin-D (vitamin D) levels were obtained in patients presenting with imaging confirmed foot and ankle osseous trauma. Variables including age, gender, ethnicity, location, season, month, anatomical location and type of bone injury were recorded. Results 308 patients were included from three different centres. 66.6% were female. The average age was 47.7 (range; 10–85). The mean hydroxyvitamin-D levels were 52.0 nmol/L (SD 28.5). 18.8% were grossly deficient, 23.7% deficient, 34.7% insufficient and 22.7% within normal range. 351 separate bone injuries were identified of which 104 were categorised as stress reactions, 134 as stress fractures, 105 as fractures and 8 non-unions. Age, gender, anatomical location and fracture type did not statistically affect vitamin D levels. Ethnicity did affect Vitamin D levels: non-Caucasians mean levels were 32.4 nmols/L compared to Caucasian levels of 53.2 nmol/L (p = 0.0026). Conclusion Only 18.8% of our trauma patients had a normal Vitamin D level and 22.7% were grossly deficient. Patient age, gender, anatomical location and injury type did not statistically affect vitamin D levels. No difference between trauma and elective patients were found. Hypovitaminosis D is a problem of society in general rather than specific to certain foot and ankle injury patterns or particular patient groups sustaining trauma. Level of evidence 2b

Effects of antiplatelet therapy on stroke risk by brain imaging features of intracerebral haemorrhage and cerebral small vessel diseases: subgroup analyses of the RESTART randomised, open-label trial

Background Findings from the RESTART trial suggest that starting antiplatelet therapy might reduce the risk of recurrent symptomatic intracerebral haemorrhage compared with avoiding antiplatelet therapy. Brain imaging features of intracerebral haemorrhage and cerebral small vessel diseases (such as cerebral microbleeds) are associated with greater risks of recurrent intracerebral haemorrhage. We did subgroup analyses of the RESTART trial to explore whether these brain imaging features modify the effects of antiplatelet therapy

Search for CP Violation in the Decay Z -> b (b bar) g

About three million hadronic decays of the Z collected by ALEPH in the years 1991-1994 are used to search for anomalous CP violation beyond the Standard Model in the decay Z -> b \bar{b} g. The study is performed by analyzing angular correlations between the two quarks and the gluon in three-jet events and by measuring the differential two-jet rate. No signal of CP violation is found. For the combinations of anomalous CP violating couplings, ${\hat{h}}_b = {\hat{h}}_{Ab}g_{Vb}-{\hat{h}}_{Vb}g_{Ab}$ and $h^{\ast}_b = \sqrt{\hat{h}_{Vb}^{2}+\hat{h}_{Ab}^{2}}$, limits of \hat{h}_b < 0.59$and$h^{\ast}_{b} < 3.02$ are given at 95\% CL.Comment: 8 pages, 1 postscript figure, uses here.sty, epsfig.st

CD47 plays a critical role in T-cell recruitment by regulation of LFA-1 and VLA-4 integrin adhesive functions

CD47 plays an important but incompletely understood role in the innate and adaptive immune responses. CD47, also called integrin-associated protein, has been demonstrated to associate in cis with β1 and β3 integrins. Here we test the hypothesis that CD47 regulates adhesive functions of T-cell α4β1 (VLA-4) and αLβ2 (LFA-1) in in vivo and in vitro models of inflammation. Intravital microscopy studies reveal that CD47(−/−) Th1 cells exhibit reduced interactions with wild-type (WT) inflamed cremaster muscle microvessels. Similarly, murine CD47(−/−) Th1 cells, as compared with WT, showed defects in adhesion and transmigration across tumor necrosis factor-α (TNF-α)–activated murine endothelium and in adhesion to immobilized intercellular adhesion molecule 1 (ICAM-1) and vascular cell adhesion protein 1 (VCAM-1) under flow conditions. Human Jurkat T-cells lacking CD47 also showed reduced adhesion to TNF-α–activated endothelium and ICAM-1 and VCAM-1. In cis interactions between Jurkat T-cell β2 integrins and CD47 were detected by fluorescence lifetime imaging microscopy. Unexpectedly, Jurkat CD47 null cells exhibited a striking defect in β1 and β2 integrin activation in response to Mn(2+) or Mg(2+)/ethylene glycol tetraacetic acid treatment. Our results demonstrate that CD47 associates with β2 integrins and is necessary to induce high-affinity conformations of LFA-1 and VLA-4 that recognize their endothelial cell ligands and support leukocyte adhesion and transendothelial migration