12,240 research outputs found

    A 0535+26: Back in business

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    In May/June 2005, after 10 years of inactivity, the Be/X-ray binary system A 0535+26 underwent a major X-ray outburst. In this paper data are presented from 10 years of optical, IR and X-ray monitoring showing the behaviour of the system during the quiescent epoch and the lead up to the new outburst. The results show the system going through a period when the Be star in the system had a minimal circumstellar disk and then a dramatic disk recovery leading, presumably, to the latest flare up of X-ray emission. The data are interpreted in terms of the state of the disk and its interaction with the neutron star companion.Comment: Accepted for publication in MNRA

    Coagulation and fragmentation processes with evolving size and shape profiles : a semigroup approach

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    We investigate a class of bivariate coagulation-fragmentation equations. These equations describe the evolution of a system of particles that are characterised not only by a discrete size variable but also by a shape variable which can be either discrete or continuous. Existence and uniqueness of strong solutions to the associated abstract Cauchy problems are established by using the theory of substochastic semigroups of operators

    INTEGRAL deep observations of the Small Magellanic Cloud

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    Deep observations of the Small Magellanic Cloud (SMC) and region were carried out in the hard X-ray band by the INTEGRAL observatory in 2008-2009. The field of view of the instrument permitted simultaneous coverage of the entire SMC and the eastern end of the Magellanic Bridge. In total, INTEGRAL detected seven sources in the SMC and five in the Magellanic Bridge; the majority of the sources were previously unknown systems. Several of the new sources were detected undergoing bright X- ray outbursts and all the sources exhibited transient behaviour except the supergiant system SMC X-1. They are all thought to be High Mass X-ray Binary (HMXB) systems in which the compact object is a neutron star.Comment: 7 pages, 10 figures Accepted for publication in MNRA

    GEO debris and interplanetary dust: fluxes and charging behavior

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    In September 1996, a dust/debris detector: GORID was launched into the geostationary (GEO) region as a piggyback instrument on the Russian Express-2 telecommunications spacecraft. The instrument began its normal operation in April 1997 and ended its mission in July 2002. The goal of this work was to use GORID's particle data to identify and separate the space debris to interplanetary dust particles (IDPs) in GEO, to more finely determine the instrument's measurement characteristics and to derive impact fluxes. While the physical characteristics of the GORID impacts alone are insufficient for a reliable distinction between debris and interplanetary dust, the temporal behavior of the impacts are strong enough indicators to separate the populations based on clustering. Non-cluster events are predominantly interplanetary, while cluster events are debris. The GORID mean flux distributions (at mass thresholds which are impact speed dependent) for IDPs, corrected for dead time, are 1.35x10^{-4} m^{-2} s^{-1} using a mean detection rate: 0.54 d^{-1}, and for space debris are 6.1x10^{-4} m^{-2} s^{-1} using a mean detection rate: 2.5 d^{-1}. Beta-meteoroids were not detected. Clusters could be a closely-packed debris cloud or a particle breaking up due to electrostatic fragmentation after high charging.Comment: * Comments: 6 pages, 4 postscript figures, in Dust in Planetary Systems 2005, Krueger, H. and Graps, A. eds., ESA Publications, SP in press (2006). For high resolution version, see: http://www.mpi-hd.mpg.de/dustgroup/~graps/dips2005/GrapsetalDIPS2005.pd

    Profits, Costs, and the Changing Structure of Dairy Farming

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    U.S. dairy production is consolidating into fewer but larger farms. This report uses data from several USDA surveys to detail that consolidation and to analyze the financial drivers of consolidation. Specifically, larger farms realize lower production costs. Although small dairy farms realize higher revenue per hundredweight of milk sold, the cost advantages of larger size allow large farms to be profitable, on average, even while most small farms are unable to earn enough to replace their capital. Further survey evidence, as well as the financial data, suggest that consolidation is likely to continue.Dairy farming, economies of scale, economies of size, dairy farm structure, milk costs, Farm Management, Industrial Organization, Livestock Production/Industries,

    Pitfalls in the use of the lung colony assay to assess T-cell function in irradiated mice.

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    Mice depleted of T lymphocytes by thymectomy, whole-body irradiation and bone-marrow reconstitution showed a marked increase in susceptibility to the development of lung colonies after i.v. injection of cells of an immunogenic fibrosarcoma. However, a similar increase was observed in unthymectomized, irradiated and reconstituted mice that had recovered their T-cell function, as evidenced by rejection of allogeneic skin grafts. In both thymectomized and unthymectomized mice subjected to whole-body irradiation, the lung-colony-forming efficiency was high 1 day after irradiation, declined to a minimum at 7 days, and thereafter increased again, unless the animals were held in a pathogen-free environment. Reconstitution of T-cell-depleted mice with thymocytes and/or a thymic lobe graft tended to increase further, rather than reduce, lung-colony-forming efficiency. Induction of profound lymphopenia, by irradiation of the whole body except the thorax, did not significantly increase lung colony yields. These studies show that the lung colony assay is not a reliable method of assessing T-cell function in irradiated mice

    Distinct Illness Representation Profiles Are Associated with Anxiety in Women Testing Positive for Human Papillomavirus

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    Background: Testing positive for human papillomavirus (HPV) at cervical cancer screening has been associated with heightened anxiety. To date, the cognitive determinants of heightened anxiety remain unclear, making it difficult to design effective interventions. Purpose: This study investigated latent illness representation profiles in women testing positive for HPV with no abnormal cells (normal cytology) and explored associations between these profiles and anxiety. Methods: Women aged 24–66 (n = 646) who had tested HPV-positive with normal cytology at routine HPV primary screening in England completed a cross-sectional survey shortly after receiving their result. Results: Latent profile analysis identified three distinct profiles of illness representations (termed “adaptive,” “negative,” and “negative somatic”), which differed significantly in their patterns of illness perceptions. Hierarchal linear regression revealed that these latent illness representation profiles accounted for 21.8% of the variance in anxiety, after adjusting for demographic and clinical characteristics. When compared with adaptive representations (Profile 1), women with negative representations (Profile 2) and negative somatic representations (Profile 3) had significantly higher anxiety, with clinically meaningful between-group differences (mean difference [MD] = 17.26, confidence interval [CI]: 14.29–20.22 and MD = 13.20, CI: 9.45–16.96 on the S-STAI-6, respectively). Conclusion: The latent illness representation profiles identified in this study provide support for the role of negative beliefs contributing to anxiety in women testing HPV-positive with normal cytology. Characteristics specific to subgroups of highly anxious women (Profiles 2 and 3) could be used by policymakers to target information in routine patient communications (e.g., test result letters) to reduce unnecessary burden. Future research should adopt longitudinal designs to understand the trajectory of illness representations from HPV diagnosis through to clearance versus persistence
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