4,478 research outputs found

    Proposed New Test of Spin Effects in General Relativity

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    The recent discovery of a double-pulsar PSR J0737-3039A/B provides an opportunity of unequivocally observing, for the first time, spin effects in general relativity. Existing efforts involve detection of the precession of the spinning body itself. However, for a close binary system, spin effects on the orbit may also be discernable. Not only do they add to the advance of the periastron (by an amount which is small compared to the conventional contribution) but they also give rise to a precession of the orbit about the spin direction. The measurement of such an effect would also give information on the moment of inertia of pulsars

    Ultraviolet Radiation from Evolved Stellar Populations: II. The Ultraviolet Upturn Phenomenon in Elliptical Galaxies

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    We present an analysis of the far-ultraviolet upturn phenomenon (UVX) observed in elliptical galaxies and spiral galaxy bulges. Our premise is that the UV radiation from these systems emanates primarily from extreme horizontal branch (EHB) stars and their progeny. We re-derive the broad-band UV colors 1500−V1500-V and 2500−V2500-V for globular clusters and elliptical galaxies from the available satellite data and investigate color-color and color-line strength correlations. We also provide the ingredients necessary for constructing models with arbitrary HB morphologies.Comment: uuencoded compressed postscript file, 60pp. (revisions on pp. 7,8,22,33,37 & 57

    Repression and Protest: The Limitations of Aggregation; Strategic Insights, v. 7 issue 2 (April 2008)

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    This article appeared in Strategic Insights, v.7 issue 2 (April 2008)Approved for public release; distribution is unlimited

    UV Properties of Galactic Globular Clusters with GALEX II. Integrated colors

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    We present ultraviolet (UV) integrated colors of 44 Galactic globular clusters (GGCs) observed with the Galaxy Evolution Explorer (GALEX) in both FUV and NUV bands. This data-base is the largest homogeneous catalog of UV colors ever published for stellar systems in our Galaxy. The proximity of GGCs makes it possible to resolve many individual stars even with the somewhat low spatial resolution of GALEX. This allows us to determine how the integrated UV colors are driven by hot stellar populations, primarily horizontal branch stars and their progeny. The UV colors are found to be correlated with various parameters commonly used to define the horizontal branch morphology. We also investigate how the UV colors vary with parameters like metallicity, age, helium abundance and concentration. We find for the first time that GCs associated with the Sagittarius dwarf galaxy have (FUV-V) colors systematically redder than GGCs with the same metallicity. Finally, we speculate about the presence of an interesting trend, suggesting that the UV color of GCs may be correlated with the mass of the host galaxy, in the sense that more massive galaxies possess bluer clusters.Comment: Accepted for publication by The Astronomical Journal. 36 pages, 9 figures, 1 tabl

    Change Is in the Air: The Hypoxic Induction of Phenotype Switching in Melanoma

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    Melanoma cells can switch from a highly proliferative, less invasive state to a highly invasive, less proliferative state, a phenomenon termed phenotype switching. This results in a highly heterogenous tumor, where a slow-growing, aggressive population of cells may resist tumor therapy, and it predicts tumor recurrence. Here we discuss the observation made by Widmer et al. that hypoxia may drive phenotype switching

    Quantum Zeno and Anti-Zeno Effects: An Exact Model

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    Recent studies suggest that both the quantum Zeno (increase of the natural lifetime of an unstable quantum state by repeated measurements) and anti-Zeno (decrease of the natural lifetime) effects can be made manifest in the same system by simply changing the dissipative decay rate associated with the environment. We present an exact calculation confirming this expectation

    Building capacity in waterbird and wetland monitoring in eastern Africa

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    The wetlands of eastern Africa support internationally important assemblages of plants and animals, and are a vital source of livelihood and water for many societies. The combined human population of Burundi, Djibouti, Eritrea, Ethiopia, Kenya, Rwanda, Sudan, Tanzania and Uganda is estimated to be about 200 million. The region has an area of about 5.6 million km2 of which only 4.5% is open water/wetlands. Wetland conversion to agriculture often provides only short-term benefits and can pose long-term problems. The ever-increasing human population density coupled with the scarce water resources in Africa have put African governments under increasing pressure to allow further exploitation and drainage of wetlands. Lack of sufficient up-to-date information to guide policy and development programmes for the respective Africa governments is considered as one of the causes for the continued loss and degradation of wetlands. To fill this information gap, it was recognized that a standardized system for monitoring wetland biodiversity and making the data and information available to governments and other stakeholders was required. In 2002, a project was implemented to build and maintain capacity in the monitoring of wetland biodiversity in eastern Africa and to provide the necessary information required for wetland conservation. This paper describes the capacity building process leading to: (1) the development of a wetlands database with query tools; (2) the provision of training in the use of the wetland monitoring database; (3) the launch of the Wetland Biodiversity Monitoring Scheme (WBMS) to provide data for use in wetland conservation and development of site management plans; and (4) training in the development of a wetland site management plan in each of the nine partner countries

    Treating Homeless Opioid Dependent Patients with Buprenorphine in an Office-Based Setting

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    CONTEXT Although office-based opioid treatment with buprenorphine (OBOT-B) has been successfully implemented in primary care settings in the US, its use has not been reported in homeless patients. OBJECTIVE To characterize the feasibility of OBOT-B in homeless relative to housed patients. DESIGN A retrospective record review examining treatment failure, drug use, utilization of substance abuse treatment services, and intensity of clinical support by a nurse care manager (NCM) among homeless and housed patients in an OBOT-B program between August 2003 and October 2004. Treatment failure was defined as elopement before completing medication induction, discharge after medication induction due to ongoing drug use with concurrent nonadherence with intensified treatment, or discharge due to disruptive behavior. RESULTS Of 44 homeless and 41 housed patients enrolled over 12 months, homeless patients were more likely to be older, nonwhite, unemployed, infected with HIV and hepatitis C, and report a psychiatric illness. Homeless patients had fewer social supports and more chronic substance abuse histories with a 3- to 6-fold greater number of years of drug use, number of detoxification attempts and percentage with a history of methadone maintenance treatment. The proportion of subjects with treatment failure for the homeless (21%) and housed (22%) did not differ (P=.94). At 12 months, both groups had similar proportions with illicit opioid use [Odds ratio (OR), 0.9 (95% CI, 0.5–1.7) P=.8], utilization of counseling (homeless, 46%; housed, 49%; P=.95), and participation in mutual-help groups (homeless, 25%; housed, 29%; P=.96). At 12 months, 36% of the homeless group was no longer homeless. During the first month of treatment, homeless patients required more clinical support from the NCM than housed patients. CONCLUSIONS Despite homeless opioid dependent patients' social instability, greater comorbidities, and more chronic drug use, office-based opioid treatment with buprenorphine was effectively implemented in this population comparable to outcomes in housed patients with respect to treatment failure, illicit opioid use, and utilization of substance abuse treatment

    Functional Stroke Symptoms: A Narrative Review and Conceptual Model

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    Stroke services have been reconfigured in recent years to facilitate early intervention. Throughout stroke settings, some patients present with functional symptoms that cannot be attributed to a structural cause. Emphasis on fast diagnosis and treatment means that a proportion of patients entering the care pathway present with functional symptoms that mimic stroke or have functional symptoms in addition to vascular stroke. There is limited understanding of mechanisms underlying functional stroke symptoms, how the treatment of such patients should be managed, and no referral pathway or treatment. Predisposing factors vary between individuals, and symptoms are heterogeneous: onset can be acute or insidious, and duration can be short-lived or chronic in the context of new or recurrent illness cognitions and behaviors. This article proposes a conceptual model of functional symptoms identified in stroke services and some hypotheses based on a narrative review of the functional neurological disorder literature. Predisposing factors may include illness experiences, stressors, and chronic autonomic nervous system arousal. Following the onset of distressing symptoms, perpetuating factors may include implicit cognitive processes, classical and operant conditioning, illness beliefs, and behavioral responses, which could form the basis of treatment targets. The proposed model will inform the development of theory-based interventions as well as a functional stroke care pathway
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