28,840 research outputs found

    Effect of tail-fin span on stability and control characteristics of a Canard-controlled missile at supersonic Mach numbers

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    An experimental wind-tunnel investigation was conducted at Mach numbers from 1.60 to 3.50 to obtain the longitudinal and lateral-directional aerodynamic characteristics of a circular, cruciform, canard-controlled missile with variations in tail-fin span. In addition, comparisons were made with the experimental aerodynamic characteristics using three missile aeroprediction programs: MISSILE1, MISSILE2, and NSWCDM. The results of the investigation indicate that for the test Mach number range, canard roll control at low angles of attack is feasible on tail-fin configurations with tail-to-canard span ratios of less than or equal to 0.75. The conards are effective pitch and yaw control devices on each tail-fin span configuration tested. Programs MISSILE1 and MISSILE2 provide very good predictions of longitudinal aerodynamic characteristics and fair predictions of lateral-directional aerodynamic characteristics at low angles of attack, with MISSILE2 predictions generally in better agreement with test data. Program NSWCDM provides good longitudinal and lateral-directional aerodynamic predictions that improve with increases in tail-tin span

    Summary of Golden Measurements at a Μ\nu-Factory

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    The precision and discovery potential of a neutrino factory based on muon storage rings is summarized. For three-family neutrino oscillations, we analyze how to measure or severely constraint the angle ξ13\theta_{13}, CP violation, MSW effects and the sign of the atmospheric mass difference Δm232\Delta m^2_{23}. The appearance of ``wrong-sign muons'' at three reference baselines is considered: 732 km, 3500 km and 7332 km. We exploit the dependence of the signal on the neutrino energy, and include as well realistic background estimations and detection efficiencies. The optimal baseline turns out to be OO(3000 km).Comment: 7 pages, Latex2e, 5 eps figures, use package espfi

    Golden measurements at a neutrino factory

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    The precision and discovery potential of a neutrino factory based on muon storage rings is studied. For three-family neutrino oscillations, we analyse how to measure or severely constraint the angle ξ13\theta_{13}, CP violation, MSW effects and the sign of the atmospheric mass difference Δm232\Delta m^2_{23}. We present a simple analytical formula for the oscillation probabilities in matter, with all neutrino mass differences non-vanishing, which clarifies the subtleties involved in disentangling the unknown parameters. The appearance of ``wrong-sign muons'' at three reference baselines is considered: 732 km, 3500 km, and 7332 km. We exploit the dependence of the signal on the neutrino energy, and include as well realistic background estimations and detection efficiencies. The optimal baseline turns out to be O(3000{\cal O}(3000 km). Analyses combining the information from different baselines are also presented.Comment: 45 pages, Latex2e, 24 figures using epsfig.sty. An incorrect statement and a few misprints have been corrected. Results and conclusions are unchange

    Use of generic and condition-specific measures of health-related quality of life in NICE decision-making: systematic review, statistical modelling and survey.

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    © Queen’s Printer and Controller of HMSO 2014Background: The National Institute for Health and Care Excellence recommends the use of generic preference-based measures (GPBMs) of health for its Health Technology Assessments (HTAs). However, these data may not be available or appropriate for all health conditions. Objectives: To determine whether GPBMs are appropriate for some key conditions and to explore alternative methods of utility estimation when data from GPBMs are unavailable or inappropriate. Design: The project was conducted in three stages: (1) A systematic review of the psychometric properties of three commonly used GPBMs [EQ-5D, SF-6D and Health Utilities Index Mark 3 (HUI3)] in four broadly defined conditions: visual impairment, hearing impairment, cancer and skin conditions. (2) Potential modelling approaches to ‘map’ EQ-5D values from condition-specific and clinical measures of health [European Organisation for Research and Treatment of Cancer Quality-of-life Questionnaire Core 30 (EORTC QLQ-C30) and Functional Assessment of Cancer Therapy – General Scale (FACT-G)] are compared for predictive ability and goodness of fit using two separate data sets. (3) Three potential extensions to the EQ-5D are developed as ‘bolt-on’ items relating to hearing, tiredness and vision. They are valued using the time trade-off method. A second valuation study is conducted to fully value the EQ-5D with and without the vision bolt-on item in an additional sample of 300 people. Main outcome measures: Comparisons of EQ-5D, SF-6D and HUI3 in four conditions with various generic and condition-specific measures. Mapping functions were estimated between EORTC QLQ-C30 and FACT-G with EQ-5D. Three bolt-ons to the EQ-5D were developed: EQ + hearing/vision/tiredness. A full valuation study was conducted for the EQ + vision. Results: (1) EQ-5D was valid and responsive for skin conditions and most cancers; in vision, its performance varied according to aetiology; and performance was poor for hearing impairments. The HUI3 performed well for hearing and vision disorders. It also performed well in cancers although evidence was limited and there was no evidence in skin conditions. There were limited data for SF-6D in all four conditions and limited evidence on reliability of all instruments. (2) Mapping algorithms were estimated to predict EQ-5D values from alternative cancer-specific measures of health. Response mapping using all the domain scores was the best performing model for the EORTC QLQ-C30. In an exploratory analysis, a limited dependent variable mixture model performed better than an equivalent linear model. In the full analysis for the FACT-G, linear regression using ordinary least squares gave the best predictions followed by the tobit model. (3) The exploratory valuation study found that bolt-on items for vision, hearing and tiredness had a significant impact on values of the health states, but the direction and magnitude of differences depended on the severity of the health state. The vision bolt-on item had a statistically significant impact on EQ-5D health state values and a full valuation model was estimated. Conclusions: EQ-5D performs well in studies of cancer and skin conditions. Mapping techniques provide a solution to predict EQ-5D values where EQ-5D has not been administered. For conditions where EQ-5D was found to be inappropriate, including some vision disorders and for hearing, bolt-ons provide a promising solution. More primary research into the psychometric properties of the generic preference-based measures is required, particularly in cancer and for the assessment of reliability. Further research is needed for the development and valuation of bolt-ons to EQ-5D.UK Medical Research Council (MRC) as part of the MRC-NIHR methodology research programme (reference G0901486

    A Multiple System of Radio Sources at the Core of the L723 Multipolar Outflow

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    We present high angular resolution Very Large Array multi-epoch continuum observations at 3.6 cm and 7 mm towards the core of the L723 multipolar outflow revealing a multiple system of four radio sources suspected to be YSOs in a region of only ~4 arcsecs (1200 AU) in extent. The 3.6 cm observations show that the previously detected source VLA 2 contains a close (separation ~0.29 arcsecs or ~90 AU) radio binary, with components (A and B) along a position angle of ~150 degrees. The northern component (VLA 2A) of this binary system is also detected in the 7 mm observations, with a positive spectral index between 3.6 cm and 7 mm. In addition, the source VLA 2A is associated with extended emission along a position angle of ~115 degrees, that we interpret as outflowing shock-ionized gas that is exciting a system of HH objects with the same position angle. A third, weak 3.6 cm source, VLA 2C, that is detected also at 7 mm, is located ~0.7 arcsecs northeast of VLA 2A, and is possibly associated with the water maser emission in the region. The 7 mm observations reveal the presence of an additional source, VLA 2D, located ~3.5 arcsecs southeast of VLA 2A, and with a 1.35 mm counterpart. All these radio continuum sources have a positive spectral index, compatible with them being YSOs. We also propose that the high velocity CO emission observed in the region could be the superposition of multiple outflows (at least three independent bipolar outflows) excited by the YSOs located at the core, instead of the previous interpretations in terms of only one or two outflows.Comment: Accepted for publication in The Astrophysical Journal (2007 December 6
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