51,168 research outputs found

    Influence of configuration details on the subsonic characteristics of a space shuttle orbiter design

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    An investigation was conducted in the Langley low-turbulence pressure tunnel of a model of a space shuttle orbiter design in order to determine the influence of minor configuration geometric details on the aerodynamic characteristics at subsonic speeds. A plane wing was tested with a small planform fillet; a twisted wing was tested with both a small and a large planform fillet. Tailored attitude-control propulsion-system wing-tip and body pods, trisegmented elevons, and canopy effects were also investigated. The tests were conducted at angles of attack from -3 deg to 24 deg for sideslip angles of 0 deg and 6 deg and at a Mach number of 0.25

    Electronic spectrum of crystalline antimony

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    Electronic spectrum of crystalline antimon

    Energy landscape and rigidity

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    The effects of floppy modes in the thermodynamical properties of a system are studied. From thermodynamical arguments, we deduce that floppy modes are not at zero frequency and thus a modified Debye model is used to take into account this effect. The model predicts a deviation from the Debye law at low temperatures. Then, the connection between the topography of the energy landscape, the topology of the phase space and the rigidity of a glass is explored. As a result, we relate the number of constraints and floppy modes with the statistics of the landscape. We apply these ideas to a simple model for which we provide an approximate expression for the number of energy basins as a function of the rigidity. This allows to understand certains features of the glass transition, like the jump in the specific heat or the reversible window observed in chalcogenide glasses.Comment: 1 text+3 eps figure

    Supporting research and development in ambulance services: research for better healthcare in prehospital settings

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    Background This paper discusses recent developments in research support for ambulance trusts in England and Wales and how this could be designed to lead to better implementation, collaboration in and initiation of high-quality research to support a truly evidence-based service. Method The National Ambulance Research Steering Group was set up in 2007 to establish the strategic direction for involvement of regional ambulance services in developing relevant and well-designed research for improving the quality of services to patients. Results Ambulance services have been working together and with academic partners to implement research and to participate, collaborate and lead the design of research that is relevant for patients and ambulance services. Conclusion New structures to support the strategic development of ambulance and prehospital research will help address gaps in the evidence for health interventions and service delivery in prehospital and ambulance care and ensure that ambulance services can increase their capacity and capability for high-quality research
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