7,009 research outputs found

    The Implications of Galaxy Formation Models for the TeV Observations of Current Detectors

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    This paper represents a step toward constraining galaxy formation models via TeV gamm a ray observations. We use semi-analytic models of galaxy formation to predict a spectral distribution for the intergalactic infrared photon field, which in turn yields information about the absorption of TeV gamma rays from extra-galactic sources. By making predictions for integral flux observations at >200 GeV for several known EGRE T sources, we directly compare our models with current observational upper limits obtained by Whipple. In addition, our predictions may offer a guide to the observing programs for the current population of TeV gamma ray observatories.Comment: 6 pages, 11 figures, to appear in the proceedings of the 6th TeV Workshop at Snowbird, U

    A Vector-Integration-to-Endpoint Model for Performance of Viapoint Movements

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    Viapoint (VP) movements are movements to a desired point that are constrained to pass through an intermediate point. Studies have shown that VP movements possess properties, such as smooth curvature around the VP, that are not explicable by treating VP movements as strict concatenations of simpler point-to-point (PTP) movements. Such properties have led some theorists to propose whole-trajectory optimization models, which imply that the entire trajectory is pre-computed before movement initiation. This paper reports new experiments conducted to systematically compare VP with PTP trajectories. Analyses revealed a statistically significant early directional deviation in VP movements but no associated curvature change. An explanation of this effect is offered by extending the Vector-Integration-To-Endpoint (VITE) model (Bullock and Grossberg, 1988), which postulates that voluntary movement trajectories emerge as internal gating signals control the integration of continuously computed vector commands based on the evolving, perceptible difference between desired and actual position variables. The model explains the observed trajectories of VP and PTP movements as emergent properties of a dynamical system that does not precompute entire trajectories before movement initiation. The new model includes a working memory and a stage sensitive to time-to-contact information. These cooperate to control serial performance. The structural and functional relationships proposed in the model are consistent with available data on forebrain physiology and anatomy.Office of Naval Research (N00014-92-J-1309, N00014-93-1-1364, N0014-95-1-0409

    NHS reforms and the working lives of midwives and physiotherapists

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    From 2000 the NHS was subjected to a series of far reaching reforms, the purposes of which were to increase the role of the primary care sector in commissioning and providing services, promote healthier life styles, reduce health inequality, and improve service standards. These were seen as requiring a greater leadership role from health professionals, closer and more cooperative working between health professionals, and between health professionals, social services, and community and other service providers. The project surveyed a random sample of midwives and physiotherapists to investigate their perceptions of the effectiveness of the reforms, and their effects on working lives. The predominant perception was that NHS reforms had negatively affected the funding of their services; and had done little to improve service quality, delivery or organisation. Although the potential existed for the reforms to improve services, the necessary resources and required staffing were not made available and the objectives of the reforms were only partially secured by intensifying of work. The downside of this was a deterioration of the sociopsychological wellbeing of midwives and physiotherapists, especially the former, exacerbating the shortage of skilled and experienced. Shortage of staff and the associated increased work burdens were demoralising and demotivating; morale and job satisfaction declined, and job insecurity and labour turnover increased

    A shared environment for microcomputer system development

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    A timeshared microcomouter monitor for Intel b 6 microprocessor systems development has been described. Running on the Sycor 440 Clustered Terminal Processina System* the monitor provides a virtual environment comoosed of a console device* eight floorv disk drives* and an b y m i c roorocessor for up to four concurrent users. Virtual floppy disk files on a five meaabvte movable-head disk provide the system's primary auxiliary storaoe medium. Three different levels of access protection are available for these virtual flopoy disk images. A command 1 a n a u a q e processor has been included to support nn-line modification of the virtual environment. System recovery in the event of a hardware or software failure is also supported by the monitor.http://archive.org/details/sharedenvironmen00browCaptain, United States Marine CorpsLieutenant, United States NavyApproved for public release; distribution is unlimited
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