1,691 research outputs found

    Chandra X-Ray Point Sources, including Supernova 1979C, in the Spiral Galaxy M100

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    Six x-ray point sources, with luminosities of 4×10382×1039ergss14 \times 10^{38} - 2 \times 10^{39} \rm ergs s^{-1} in the 0.4--7 keV band, were detected in Chandra observations of the spiral galaxy M100. One source is identified with supernova SN 1979C and appears to have roughly constant x-ray flux for the period 16--20 years after the outburst. The x-ray spectrum is soft, as would be expected if the x-ray emission is due to the interaction of supernova ejecta with circumstellar matter. Most of the other sources are variable either within the Chandra observation or when compared to archival data. None are coincident with the peak of the radio emission at the nucleus. These sources have harder spectra than the supernova and are likely x-ray binaries. M100 has more bright x-ray sources than typical for spiral galaxies of its size. This is likely related to active star formation occurring in the galaxy.Comment: accepted by the Astrophysical Journal, 7 page

    Does the arXiv lead to higher citations and reduced publisher downloads for mathematics articles?

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    An analysis of 2,765 articles published in four math journals from 1997 to 2005 indicate that articles deposited in the arXiv received 35% more citations on average than non-deposited articles (an advantage of about 1.1 citations per article), and that this difference was most pronounced for highly-cited articles. Open Access, Early View, and Quality Differential were examined as three non-exclusive postulates for explaining the citation advantage. There was little support for a universal Open Access explanation, and no empirical support for Early View. There was some inferential support for a Quality Differential brought about by more highly-citable articles being deposited in the arXiv. In spite of their citation advantage, arXiv-deposited articles received 23% fewer downloads from the publisher's website (about 10 fewer downloads per article) in all but the most recent two years after publication. The data suggest that arXiv and the publisher's website may be fulfilling distinct functional needs of the reader.Comment: Last updated May 02, 200

    Health-related Quality of Life in Pediatric Patients With Chronic Hepatitis B Living in the United States and Canada

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    OBJECTIVES: The aim of the study was to determine whether selected sociodemographic and hepatitis B virus (HBV)-specific clinical factors are associated with health-related quality of life (HRQoL) among pediatric patients chronically infected with HBV. METHODS: Children with chronic HBV enrolled in the Hepatitis B Research Network completed the Child Health Questionnaire at study entry. Caregivers of children 5 to <10 years completed the parent-reported form (CHQ-Parent Report Form); youth 10 to <18 years completed the child-reported CHQ-Child Report Form. We examined univariable associations of the Child Health Questionnaire scores with selected independent variables: sex, adoption status, maternal education, alanine aminotransferase (U/L), aspartate aminotransferase-to-platelet ratio index, and HBV-specific symptom count. RESULTS: A total of 244 participants (83 young children 5-<10 years, 161 youth 10-<18 years) were included, all HBV treatment-naïve. Among young children, increased alanine aminotransferase level was negatively associated with CHQ-Parent Report Form psychosocial summary t score (r = -0.28, P = 0.01). No other subscale comparisons for young children were statistically significant. Among youth, adoption was associated with better physical functioning and general health (P < 0.01). Higher maternal education was associated with better role/functioning-physical and -emotional scores (P < 0.05). Maternal education and adoption status were linked with adoption associated with higher maternal education. Increased symptom count in youth was associated with worse HRQoL in subscales measuring bodily pain, behavior, mental health, and self-esteem (P < 0.01). CONCLUSIONS: Although overall HRQoL is preserved in children with chronic HBV, some sociodemographic and HBV-related clinical factors were associated with impaired HRQoL in our pediatric patients at baseline. Measurement of HRQoL can focus resources on education and psychosocial support in children and families most in need

    WormBase: a multi-species resource for nematode biology and genomics

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    WormBase (http://www.wormbase.org/) is the central data repository for information about Caenorhabditis elegans and related nematodes. As a model organism database, WormBase extends beyond the genomic sequence, integrating experimental results with extensively annotated views of the genome. The WormBase Consortium continues to expand the biological scope and utility of WormBase with the inclusion of large-scale genomic analyses, through active data and literature curation, through new analysis and visualization tools, and through refinement of the user interface. Over the past year, the nearly complete genomic sequence and comparative analyses of the closely related species Caenorhabditis briggsae have been integrated into WormBase, including gene predictions, ortholog assignments and a new synteny viewer to display the relationships between the two species. Extensive site-wide refinement of the user interface now provides quick access to the most frequently accessed resources and a consistent browsing experience across the site. Unified single-page views now provide complete summaries of commonly accessed entries like genes. These advances continue to increase the utility of WormBase for C.elegans researchers, as well as for those researchers exploring problems in functional and comparative genomics in the context of a powerful genetic system

    Durability of Response in Children Treated with Pegylated Interferon alfa-2a +/- Ribavirin for Chronic Hepatitis C

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    Objectives: No long-term data have been published on the durability of response following pegylated interferon (PegIFN) treatment in children with chronic hepatitis C. This prospective, multicenter, long-term follow-up (LTFU) study aimed to assess long-term durability of sustained virological response (SVR), long-term safety and tolerability, and the association between IL28B genotype and treatment response, in children previously treated with PegIFN alfa-2a ± ribavirin (RBV) in the PEDS-C trial. Methods: A total of 93 patients were assessed for enrollment, and 38 enrolled in the study. Patients attended 2 study visits: 5 (mean 5.6, range 4.1–6.6) and 6 (6.6, 5.1–7.7) years after treatment cessation. Standardized medical history, physical examination, and laboratory testing were performed at these visits. Reminder telephone calls were conducted at 4 and 8 months after the initial visit. Results: The LTFU cohort was the representative of the original PEDS-C cohort because both baseline and treatment characteristics were comparable. Of the 38 participants, 21 achieved SVR (responders) during the PEDS-C trial and 17 had not (nonresponders). All 21 responders maintained undetectable hepatitis C virus RNA during the LTFU (4.4–7.0 years after achieving SVR) in contrast to the nonresponders who demonstrated persistent viremia. IL28B CC genotype was associated with SVR (67% vs 30% in non-CC, P = 0.028). Conclusion: Long-term durability of SVR is excellent following PegIFN alfa-2a treatment in children with chronic hepatitis C; SVR is higher in those with IL28B CC versus non-CC

    WormBase: a comprehensive resource for nematode research

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    WormBase (http://www.wormbase.org) is a central data repository for nematode biology. Initially created as a service to the Caenorhabditis elegans research field, WormBase has evolved into a powerful research tool in its own right. In the past 2 years, we expanded WormBase to include the complete genomic sequence, gene predictions and orthology assignments from a range of related nematodes. This comparative data enrich the C. elegans data with improved gene predictions and a better understanding of gene function. In turn, they bring the wealth of experimental knowledge of C. elegans to other systems of medical and agricultural importance. Here, we describe new species and data types now available at WormBase. In addition, we detail enhancements to our curatorial pipeline and website infrastructure to accommodate new genomes and an extensive user base
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