443 research outputs found

    Discovery of the Putative Pulsar and Wind Nebula Associated with the TeV Gamma-ray Source HESS J1813-178

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    We present a Chandra X-ray observation of G12.82-0.02, a shell-like radio supernova remnant coincident with the TeV gamma-ray source HESS J1813-178. We resolve the X-ray emission from the co-located ASCA source into a point source surrounded by structured diffuse emission that fills the interior of the radio shell. The morphology of the diffuse emission strongly resembles that of a pulsar wind nebula. The spectrum of the compact source is well-characterized by a power-law with index Gamma approx 1.3, typical of young and energetic rotation-powered pulsars. For a distance of 4.5 kpc, consistent with the X-ray absorption and an association with the nearby star formation region W33, the 2-10 keV X-ray luminosities of the putative pulsar and nebula are L(PSR) = 3.2E33 ergs/s and L(PWN) = 1.4E34 ergs/s, respectively. Both the flux ratio of L(PWN)/L(PSR) = 4.3 and the total luminosity of this system predict a pulsar spin-down power of Edot > 1E37 ergs/s, placing it within the ten most energetic young pulsars in the Galaxy. A deep search for radio pulsations using the Parkes telescope sets an upper-limit of approx 0.07 mJy at 1.4 GHz for periods >~ 50 ms. We discuss the energetics of this source, and consider briefly the proximity of bright H2 regions to this and several other HESS sources, which may produce their TeV emission via inverse Compton scattering.Comment: 7 pages, 6 figure, Latex, emulateapj style. To appear in the Astrophysical Journa

    High-redshift Cool-core Galaxy Clusters Detected via the Sunyaev-Zel'dovich Effect in the South Pole Telescope Survey

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    We report the first investigation of cool-core properties of galaxy clusters selected via their Sunyaev-Zel'dovich (SZ) effect. We use 13 galaxy clusters uniformly selected from 178 deg2 observed with the South Pole Telescope (SPT) and followed up by the Chandra X-ray Observatory. They form an approximately mass-limited sample (>3 × 10^(14) M_☉ h^(–1)_(70)) spanning redshifts 0.3 0.5 cool-core clusters, including two strong cool cores. This rules out the hypothesis that there are no z > 0.5 clusters that qualify as strong cool cores at the 5.4σ level. The fraction of strong cool-core clusters in the SPT sample in this redshift regime is between 7% and 56% (95% confidence). Although the SPT selection function is significantly different from the X-ray samples, the high-z c_(SB) distribution for the SPT sample is statistically consistent with that of X-ray-selected samples at both low and high redshifts. The cool-core strength is inversely correlated with the offset between the brightest cluster galaxy and the X-ray centroid, providing evidence that the dynamical state affects the cool-core strength of the cluster. Larger SZ-selected samples will be crucial in understanding the evolution of cluster cool cores over cosmic time

    A GLIMPSE into the Nature of Galactic Mid-IR Excesses

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    We investigate the nature of the mid-IR excess for 31 intermediate-mass stars that exhibit an 8 micron excess in either the Galactic Legacy Infrared Mid-Plane Survey Extraordinaire or the Mid-Course Space Experiment using high resolution optical spectra to identify stars surrounded by warm circumstellar dust. From these data we determine projected stellar rotational velocities and estimate stellar effective temperatures for the sample. We estimate stellar ages from these temperatures, parallactic distances, and evolutionary models. Using MIPS [24] measurements and stellar parameters we determine the nature of the infrared excess for 19 GLIMPSE stars. We find that 15 stars exhibit Halpha emission and four exhibit Halpha absorption. Assuming that the mid-IR excesses arise in circumstellar disks, we use the Halpha fluxes to model and estimate the relative contributions of dust and free-free emission. Six stars exhibit Halpha fluxes that imply free-free emission can plausibly explain the infrared excess at [24]. These stars are candidate classical Be stars. Nine stars exhibit Halpha emission, but their Halpha fluxes are insufficient to explain the infrared excesses at [24], suggesting the presence of a circumstellar dust component. After the removal of the free-free component in these sources, we determine probable disk dust temperatures of Tdisk~300-800 K and fractional infrared luminosities of L(IR)/L(*)~10^-3. These nine stars may be pre-main-sequence stars with transitional disks undergoing disk clearing. Three of the four sources showing Halpha absorption exhibit circumstellar disk temperatures ~300-400 K, L(IR)/L(*)~10^-3, IR colors K-[24]< 3.3, and are warm debris disk candidates. One of the four Halpha absorption sources has K-[24]> 3.3 implying an optically thick outer disk and is a transition disk candidate.Comment: 17 figures. Accepted for publication in Ap

    The Blanco Cosmology Survey: Data Acquisition, Processing, Calibration, Quality Diagnostics and Data Release

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    The Blanco Cosmology Survey (BCS) is a 60 night imaging survey of \sim80 deg2^2 of the southern sky located in two fields: (α\alpha,δ\delta)= (5 hr, 55-55^{\circ}) and (23 hr, 55-55^{\circ}). The survey was carried out between 2005 and 2008 in grizgriz bands with the Mosaic2 imager on the Blanco 4m telescope. The primary aim of the BCS survey is to provide the data required to optically confirm and measure photometric redshifts for Sunyaev-Zel'dovich effect selected galaxy clusters from the South Pole Telescope and the Atacama Cosmology Telescope. We process and calibrate the BCS data, carrying out PSF corrected model fitting photometry for all detected objects. The median 10σ\sigma galaxy (point source) depths over the survey in grizgriz are approximately 23.3 (23.9), 23.4 (24.0), 23.0 (23.6) and 21.3 (22.1), respectively. The astrometric accuracy relative to the USNO-B survey is 45\sim45 milli-arcsec. We calibrate our absolute photometry using the stellar locus in grizJgrizJ bands, and thus our absolute photometric scale derives from 2MASS which has 2\sim2% accuracy. The scatter of stars about the stellar locus indicates a systematics floor in the relative stellar photometric scatter in grizgriz that is \sim1.9%, \sim2.2%, \sim2.7% and\sim2.7%, respectively. A simple cut in the AstrOmatic star-galaxy classifier {\tt spread\_model} produces a star sample with good spatial uniformity. We use the resulting photometric catalogs to calibrate photometric redshifts for the survey and demonstrate scatter δz/(1+z)=0.054\delta z/(1+z)=0.054 with an outlier fraction η<5\eta<5% to z1z\sim1. We highlight some selected science results to date and provide a full description of the released data products.Comment: 23 pages, 23 figures . Response to referee comments. Paper accepted for publication. BCS catalogs and images available for download from http://www.usm.uni-muenchen.de/BC

    Predicting disease progression in behavioral variant frontotemporal dementia

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    Introduction: The behavioral variant of frontotemporal dementia (bvFTD) is a rare neurodegenerative disease. Reliable predictors of disease progression have not been sufficiently identified. We investigated multivariate magnetic resonance imaging (MRI) biomarker profiles for their predictive value of individual decline. Methods: One hundred five bvFTD patients were recruited from the German frontotemporal lobar degeneration (FTLD) consortium study. After defining two groups ("fast progressors" vs. "slow progressors"), we investigated the predictive value of MR brain volumes for disease progression rates performing exhaustive screenings with multivariate classification models. Results: We identified areas that predict disease progression rate within 1 year. Prediction measures revealed an overall accuracy of 80% across our 50 top classification models. Especially the pallidum, middle temporal gyrus, inferior frontal gyrus, cingulate gyrus, middle orbitofrontal gyrus, and insula occurred in these models. Discussion: Based on the revealed marker combinations an individual prognosis seems to be feasible. This might be used in clinical studies on an individualized progression model

    Balanced Crystalloids versus Saline in Critically Ill Adults — A Systematic Review with Meta-Analysis

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    BACKGROUND: The comparative efficacy and safety of balanced crystalloid solutions and saline for fluid therapy in critically ill adults remain uncertain. METHODS: We systematically reviewed randomized clinical trials (RCTs) comparing the use of balanced crystalloids with saline in critically ill adults. The primary outcome was 90-day mortality after pooling data from low-risk-of-bias trials using a random-effects model. We also performed a Bayesian meta-analysis to describe the primary treatment effect in probability terms. Secondary outcomes included the incidence of acute kidney injury (AKI), new treatment with renal replacement therapy (RRT), and ventilator-free and vasopressor-free days to day 28. RESULTS: We identified 13 RCTs, comprising 35,884 participants. From six trials (34,450 participants) with a low risk of bias, the risk ratio (RR) for 90-day mortality with balanced crystalloids versus saline was 0.96 (95% confidence interval [CI], 0.91 to 1.01; I2 = 12.1%); using vague priors, the posterior probability that balanced crystalloids reduce mortality was 89.5%. The RRs of developing AKI and of being treated with RRT with balanced crystalloids versus saline were 0.96 (95% CI, 0.89 to 1.02) and 0.95 (95% CI, 0.81 to 1.11), respectively. Ventilator-free days (mean difference, 0.18 days; 95% CI, −0.45 to 0.81) and vasopressor-free days (mean difference, 0.19 days; 95% CI, −0.14 to 0.51) were similar between groups. CONCLUSIONS: The estimated effect of using balanced crystalloids versus saline in critically ill adults ranges from a 9% relative reduction to a 1% relative increase in the risk of death, with a high probability that the average effect of using balanced crystalloids is to reduce mortality

    Co-location as a catalyst for service innovation : a study of Scottish health and social care

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    Academic literature and policy on co-location of local public services focus on the cost benefits. Other benefits and outcomes of co-location, including service innovations benefiting users, are under-conceptualized. This paper suggests a framework for evaluating co-location as a learning environment for innovation, drawing on new case studies of five Community Health Partnerships in Scotland charged with more closely coordinating health and social care. We conclude that partnerships using co-location are benefiting from additional service innovations

    Play at work, learning and innovation

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    Suggesting a virtuous triangle constituting public service innovation of new governances, innovation and learning, the paper examines how and why a particular mode of learning occurs: that of play. Having identified an absence of research literature on play as a catalyst for new ideas in public services, the paper argues that the diversified nature of public services and disciplinary intermixing offers fertile ground for playing with new service ideas. Our conception of play avoids functional interpretations, such as Amabile or individualizing the results of play and instead draws upon Vygotsky’s social learning theory to conceptualize play as a group activity from which new ideas emerge and suggest a new framework for understanding purposive play at work and the contribution it can make to public service innovation

    The therapeutic potential of attentional bias modification training for insomnia: study protocol for a randomised controlled trial.

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    The efficacy of attentional bias modification (ABM) as a treatment for anxiety and depression has been extensively studied with promising results. Despite some evidence of sleep-related attentional biases in insomnia, only a small number of studies, yielding mixed results, have examined the application of ABM in insomnia. This study specifically aims to determine whether ABM can reduce (i) the presence of an attentional bias for sleep-related threatening words; (ii) insomnia symptom severity; (iii) sleep onset latency; and (iv) pre-sleep cognitive arousal amongst individuals with insomnia compared to a non-treatment control group of individuals with insomnia. We propose a randomised controlled trial of 90 individuals from the general population who meet the criteria for Insomnia Disorder. Following an initial examination for the presence of a sleep-related attentional bias using the dot-probe paradigm, participants will be randomised to an online attentional bias modification training condition, or to a standard attentional bias task (non-treatment) control condition. Both conditions will be delivered online by a web platform. All participants allocated to the non-treatment control group will be offered ABM training once the study is complete. The primary outcome will be the attentional bias indices of vigilance and disengagement and self-reported insomnia symptoms, sleep onset latency and pre-sleep cognitive arousal. Attentional bias and insomnia symptoms will be assessed at baseline (day 1) and post-treatment (2 days after the final training session: day 9). Insomnia symptoms will be again assessed at follow-up (day 16). Secondary outcomes include examining whether sleep associated monitoring and worry are related to a sleep-related attentional bias in insomnia, and whether such reports reduce following ABM. All main analyses will be carried out on completion of follow-up assessments. The trial is supported by the Department of Psychology, Sociology and Politics at Sheffield Hallam University. This study will extend the research base examining the efficacy of attentional bias modification for insomnia. ISRCTN ( ISRCTN11643569 , registered on 5 June 2018)
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