2,708 research outputs found

    Metric Subregularity and the Proximal Point Method

    Get PDF
    We examine the linear convergence rates of variants of the proximal point method for finding zeros of maximal monotone operators. We begin by showing how metric subregularity is sufficient for linear convergence to a zero of a maximal monotone operator. This result is then generalized to obtain convergence rates for the problem of finding a common zero of multiple monotone operators by considering randomized and averaged proximal methods.Comment: 14 page

    Spectroscopy from 2 to 200 keV

    Get PDF
    The astrophysical processes responsible for line and continuum emission in the spectra range 2 keV to 200 keV are examined from the viewpoint of designing a spectrometer which would operate in this regime. Phenomena considered include fluorescent line radiation in X-ray binaries, magnetically shifted iron lines and cyclotron emission from neutron star surfaces, line emission from cosmically abundant elements in thermal plasmas, and nuclear deexcitation lines in fresh nucleosynthetically produced matter. An instrument consisting of a approximately 10 sq cm array of planar germanium detectors surrounded by a large sodium-iodide anticoincidence shield is described and projected background rates and sensitivities are considered. A sample observing program for a two-day shuttle-based mission is included as an example of the wide range of scientific questions which could be addressed by such an instrument

    Inequality and Procedural Justice in Social Dilemmas

    Get PDF
    This study investigates the influence of resource inequality and the fairness of the allocation procedure of unequal resources on cooperative behavior in social dilemmas. We propose a simple formal behavioral model that incorporates conflicting selfish and social motivations. This model allows us to predict how inequality influences cooperative behavior. Allocation of resources is manipulated by three treatments that vary in terms of procedural justice: allocating resources randomly, based on merit, and based on ascription. As predicted, procedural justice influences cooperation significantly. Moreover, gender is found to be an important factor interacting with the association between procedural justice and cooperative behavior.

    Long-Term X-ray Monitoring of 1E 1740.7-2942 and GRS 1758-258

    Full text link
    We report on long-term observations of the Galactic-bulge black hole candidates 1E 1740.7-2942 and GRS 1758-258 with the Rossi X-Ray Timing Explorer. 1E 1740.7-2942 has been observed 77 times and GRS 1758-258 has been observed 82 times over the past 1000 days. The flux of each object has varied by no more than a factor of 2.5 during this period, and the indices of the energy spectra have varied by no more than 0.4. The power spectra are similar to other black-hole candidates: flat-topped noise, breaking to a power law. Each object has exhibited a brightening that lasted for several months, and we have a found a time lag between the photon power-law index and the count rate. In both sources, the spectrum is softest during the decline from the brightening. This behavior can be understood in the context of thin-disk and advection-dominated accretion flows coexisting over a wide range of radii, with the implication that both sources have low-mass companions and accrete via Roche-lobe overflow.Comment: Accepted for publication in The Astrophysical Journa

    XTE J1739-302: An Unusual New X-ray Transient

    Get PDF
    A new x-ray transient, designated XTE J1739-302, was discovered with the Proportional Counter Array (PCA) on the Rossi X-ray Timing Explorer (RXTE) in data from 12 August 1997. Although it was the brightest source in the Galactic Center region while active (about 3.0 x 10^-9 ergs/cm2/s from 2 to 25 keV), it was only observed on that one day; it was not detectable nine days earlier or two days later. There is no known counterpart at other wavelengths, and its proximity to the Galactic Center will make such an identification difficult due to source confusion and extinction. The x-ray spectrum and intensity suggest a giant outburst of a Be/neutron star binary, although no pulsations were observed and the outburst was shorter than is usual from these systems.Comment: 11 pages incorporating 6 figures, AAStex; accepted for The Astrophysical Journal, Part 2 (Letters

    A coded aperture imaging system optimized for hard X-ray and gamma ray astronomy

    Get PDF
    A coded aperture imaging system was designed for the Gamma-Ray imaging spectrometer (GRIS). The system is optimized for imaging 511 keV positron-annihilation photons. For a galactic center 511-keV source strength of 0.001 sq/s, the source location accuracy is expected to be + or - 0.2 deg

    A comparison of the illness beliefs of people with angina and their peers: a questionnaire study

    Get PDF
    BACKGROUND: What people believe about their illness may affect how they cope with it. It has been suggested that such beliefs stem from those commonly held within society . This study compared the beliefs held by people with angina, regarding causation and coping in angina, with the beliefs of their friends who do not suffer from angina. METHODS: Postal survey using the York Angina Beliefs Questionnaire (version 1), which elicits stress attributions and misconceived beliefs about causation and coping. This was administered to 164 people with angina and their non-cohabiting friends matched for age and sex. 132 people with angina and 94 friends completed the questionnaire. RESULTS: Peers are more likely than people with angina to believe that angina is caused by a worn out heart (p <0.01), angina is a small heart attack (p = 0.02), and that it causes permanent damage to the heart (p <0.001). Peers were also more likely to believe that people with angina should take life easy (p <0.01) and avoid exercise (p = 0.04) and excitement (p <0.01). CONCLUSIONS: The beliefs of the peer group about causation and coping in angina run counter to professional advice. Over time this may contribute to a reduction in patient concordance with risk factor reduction, and may help to create cardiac invalids

    AROUSING FEAR IN DENTAL HEALTH EDUCATION * , †

    Full text link
    Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/65851/1/j.1752-7325.1965.tb00484.x.pd

    Formal change impact analyses for emulated control software

    Get PDF
    Processor emulators are a software tool for allowing legacy computer programs to be executed on a modern processor. In the past emulators have been used in trivial applications such as maintenance of video games. Now, however, processor emulation is being applied to safety-critical control systems, including military avionics. These applications demand utmost guarantees of correctness, but no verification techniques exist for proving that an emulated system preserves the original system’s functional and timing properties. Here we show how this can be done by combining concepts previously used for reasoning about real-time program compilation, coupled with an understanding of the new and old software architectures. In particular, we show how both the old and new systems can be given a common semantics, thus allowing their behaviours to be compared directly
    corecore