5,317 research outputs found

    VLT near-infrared spectra of hard serendipitous Chandra sources

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    We present near-infrared long-slit spectra of eight optically-dim X-ray sources obtained with ISAAC on the Very Large Telescope. Six of the sources have hard X-ray emission with a significant fraction of the counts emerging above 2 keV. All were discovered serendipitously in the fields of three nearby galaxy clusters observed with Chandra, and identified through near-infrared imaging. The X-ray fluxes lie close to the break in the source counts. Two of the sources show narrow emission lines, and a third has a broad line. One of the narrow line-emitting sources has a clear redshift identification at z=2.18, while the other has a tentative determination based on the highest redshift detection of He I 10830 at z=1.26. The remainder have featureless spectra to deep limiting equivalent widths of 20--60 angstroms and line flux approx= 5 x 10^{-17} erg/s/cm^2 in the K-band. High-quality J, H and Ks--band images of the sources were combined with archival optical detections or limits to estimate a photometric redshift for six. Two sources show complex double morphology. The hard sources have spectral count ratios consistent with heavily obscured AGN, while the host galaxy emits much of the optical and near-infrared flux. The most likely explanation for the featureless continua is that the line photons are being scattered or destroyed by optically-thick gas and associated dust with large covering fractions.Comment: Replaced in response to problems with the PDF version of Fig 4 at arxiv.org, but not at the mirror sites (lanl.gov, soton.ac.uk). No content change

    WISE view of Narrow-Line Seyfert 1 galaxies: mid-infrared color and variability

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    We present the color and flux variability analysis at 3.4 {\mu}m (W1-band) and 4.6 {\mu}m (W 2-band) of 492 narrow-line Seyfert 1 (NLSy1) galaxies using archival data from the Wide-field Infrared Survey Explorer (WISE). In the WISE color-color, (W1 - W2) versus (W2 - W3) diagram, ~58% of the NLSy1 galaxies of our sample lie in the region occupied by the blazar category of active galactic nuclei (AGN). The mean W1 - W2 color of candidate variable NLSy1 galaxies is 0.99±0.180.99 \pm 0.18 mag. The average amplitude of variability is 0.11±0.070.11 \pm 0.07 mag in long-term (multi-year) with no difference in variability between W1 and W2-bands. The W1 - W2 color of NLSy1 galaxies is anti-correlated with the relative strength of [O III] to H{\beta}, strongly correlated with continuum luminosity, black hole mass, and Eddington ratio. The long-term amplitude of variability shows weak anti-correlation with the Fe II strength, continuum luminosity and Eddington ratio. A positive correlation between color as well as the amplitude of variability with the radio power at 1.4 GHz was found for the radio-detected NLSy1 galaxies. This suggests non-thermal synchrotron contribution to the mid-infrared color and flux variability in radio-detected NLSy1 galaxies.Comment: 10 pages; Accepted for publication in MNRA

    An Evaluation of Risk Management Courses Offered in Engineering Management Programs

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    For this paper, the authors have surveyed a total of 22 engineering management (EM) programs in the United States (both accredited and non-accredited). The purpose of this study was to analyze the offering of risk management courses as part of the engineering management curriculum. The findings showed that the majority of the programs did not offer a single dedicated course on risk management and merely covered the topic as part of other courses such as project management. The authors have made recommendations that risk management should be included as a required part of the EM curriculum due to the higher prevalence of risk in today\u27s ever changing business environment

    Utility of Papanicolaou’s smears in the diagnosis of premalignant and malignant lesions of the cervix in a tertiary care centre of South Gujarat, India

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    Background: "Preventable but not prevented", this is the reality of cervical cancer today, at least in developing countries. 80% of all the cases of cervical cancer occur in these developing countries. In India, cervical cancer is the leading cause of cancer related deaths in women. The Papanicolaou test is simple, quick, and painless. It is capable of detecting cervical cancer at an early stage and is used widely in developed countries, where it has decreased both the incidence and mortality of cervical cancer. Objective of the study was conducted to determine the importance of conventional Pap smears for the diagnosis of inflammatory, premalignant and malignant lesions of the cervix.Methods: This cross-sectional study was conducted from January 2017 to June 2018 on 2000 women coming for a Pap smear examination in Government Medical College attached to New Civil Hospital, Surat. After doing Pap stain, all cases were reported as per the 2014 Bethesda system.Results: A total of 2000 cases of Pap smears were received out of which 1914(95.7%) cases were satisfactory for evaluation, 86(4.3%) cases were unsatisfactory. The frequency of epithelial abnormalities was 3.66%. The age group of 51-60 years showed the highest epithelial abnormalities. The frequency of epithelial abnormalities in asymptomatic women was 2.3%. Out of the 1844 cases, 103(5.6%) showed changes of atrophy, 1011(54.8%) cases showed inflammatory/reactive changes, whereas organisms were seen in 558(30.3%) cases.Conclusions: Pap smear happens to be an economical, safe and pragmatic diagnostic tool for early detection of cervical cancer

    Optical and near-infrared observations of hard serendipitous Chandra sources

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    We have been carrying out a successful observational programme targeted at finding the highly obscured quasars that are thought to be the main contributors to the hard X-ray background. Out of 56 sources so far studied with optical and near-infrared imaging and spectroscopy, we have found three definite and a further twelve possible Type II quasars. Few sources show significant line emission, suggesting that the line photons are depleted by the large columns of obscuring matter. The redshift distribution of our sources shows a distinct peak at z~1. The broad-band colours and magnitudes of the optical/near-infrared counterparts indicate that the light in these bands is dominated by the continuum of a massive bright galaxy.Comment: Astron. Nachr. in press, issue dedicated to the proceedings of the workshop "X-ray Surveys in the light of New Observatories", Sep. 2002, Santander, Spai

    An Unusual Case of Moraxella osleonsis Bacteremia in an Immunocompetent Patient With SARS-CoV-2 Infection.

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    Moraxella osleonsis (M.osleonsis ) is an organism that rarely presents with bacteremia in immunocompetent patients. We report a case of an immunocompetent 59-year-old male with a recent SARS-CoV-2 infection that developed M. osleonsis bacteremia. We believe that SARS-CoV-2 infection may have played a role in developing M. osleonsis bacteremia in this patient and may be one of the first reported cases of such bacteremia in a COVID-19 patient

    Structure of a tetrameric MscL in an expanded intermediate state

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    The ability of cells to sense and respond to mechanical force underlies diverse processes such as touch and hearing in animals, gravitropism in plants, and bacterial osmoregulation. In bacteria, mechanosensation is mediated by the mechanosensitive channels of large (MscL), small (MscS), potassium-dependent (MscK) and mini (MscM) conductances. These channels act as 'emergency relief valves' protecting bacteria from lysis upon acute osmotic down-shock. Among them, MscL has been intensively studied since the original identification and characterization 15 years ago. MscL is reversibly and directly gated by changes in membrane tension. In the open state, MscL forms a non-selective 3 nS conductance channel which gates at tensions close to the lytic limit of the bacterial membrane. An earlier crystal structure at 3.5 Å resolution of a pentameric MscL from Mycobacterium tuberculosis represents a closed-state or non-conducting conformation. MscL has a complex gating behaviour; it exhibits several intermediates between the closed and open states, including one putative non-conductive expanded state and at least three sub-conducting states. Although our understanding of the closed and open states of MscL has been increasing, little is known about the structures of the intermediate states despite their importance in elucidating the complete gating process of MscL. Here we present the crystal structure of a carboxy-terminal truncation mutant (Delta95–120) of MscL from Staphylococcus aureus (SaMscL(CDelta26)) at 3.8 Å resolution. Notably, SaMscL(CDelta26) forms a tetrameric channel with both transmembrane helices tilted away from the membrane normal at angles close to that inferred for the open state, probably corresponding to a non-conductive but partially expanded intermediate state

    Management of Pain in Children with Burns

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    Burn injuries are common in children under 10 years of age. Thermal injury is the most common mechanism of injury and scalds account for >60% of such injuries. All children with burns will experience pain, regardless of the cause, size, or burn depth. Undertreated pain can result in noncompliance with treatment and, consequently, prolonged healing. It is acknowledged that the monitoring and reporting of pain in children with burns has generally been poor. Due to the adverse physiological and emotional effects secondary to pain, adequate pain control is an integral and requisite component in the management of children with burns. A multidisciplinary approach is frequently necessary to achieve a robust pain relief. Key to successful treatment is the continuous and accurate assessment of pain and the response to therapy. This clinical review article discusses the essential aspects of the pathophysiology of burns in children provides an overview of pain assessment, the salient principles in managing pain, and the essential pharmacodynamics of commonly used drugs in children with burn injuries. Both pharmacological and nonpharmacological treatment options are discussed, although a detailed review of the latter is beyond the scope and remit of this article
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