14,284 research outputs found

    Development of phase-change coatings for use as variable thermal control surfaces Final report

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    Phase change coatings for use as variable thermal control surface

    Development of phase-change coatings for use as variable thermal control surfaces Final report, 8 Mar. 1967 - 8 Mar. 1968

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    Development of phase-change coatings for thermal control of spacecraft surface

    Direct Observation of the Fourth Star in the Zeta Cancri System

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    Direct imaging of the zeta Cnc system has resolved the fourth star in the system, which is in orbit around zeta Cnc C. The presence of the fourth star has been inferred for many years from irregularities in the motion of star C, and recently from C's spectroscopic orbit. However, its mass is close to that of C, making its non-detection puzzling. Observing at wavelengths of 1.2, 1.7, and 2.2 microns with the adaptive-optics system of the CFHT, we have obtained images which very clearly reveal star D and show it to have the color of an M2 star. Its brightness is consonant with its being two M stars, which are not resolved in our observations but are likely to be in a short-period orbit, thereby accounting for the large mass and the difficulty of detection at optical wavelengths, where the magnitude difference is much larger. The positions and colors of all four stars in the system are reported and are consistent with the most recent astrometric observations.Comment: 7 pages including 3 tables, 1 figure; To appear in PAS

    The reduced cost of providing a nationally recognised service for familial hypercholesterolaemia

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    OBJECTIVE: Familial hypercholesterolaemia (FH) affects 1 in 500 people in the UK population and is associated with premature morbidity and mortality from coronary heart disease. In 2008, National Institute for Health and Care Excellence (NICE) recommended genetic testing of potential FH index cases and cascade testing of their relatives. Commissioners have been slow to respond although there is strong evidence of cost and clinical effectiveness. Our study quantifies the recent reduced cost of providing a FH service using generic atorvastatin and compares NICE costing estimates with three suggested alternative models of care (a specialist-led service, a dual model service where general practitioners (GPs) can access specialist advice, and a GP-led service).METHODS: Revision of existing 3?year costing template provided by NICE for FH services, and prediction of costs for running a programme over 10?years. Costs were modelled for the first population-based FH service in England which covers Southampton, Hampshire, Isle of Wight and Portsmouth (SHIP). Population 1.95 million.RESULTS: With expiry of the Lipitor (Pfizer atorvastatin) patent the cost of providing a 10-year FH service in SHIP reduces by 42.5% (£4.88 million on patent vs £2.80 million off patent). Further cost reductions are possible as a result of the reduced cost of DNA testing, more management in general practice, and lower referral rates to specialists. For instance a dual-care model with GP management of patients supported by specialist advice when required, costs £1.89 million.CONCLUSIONS: The three alternative models of care are now <50% of the cost of the original estimates undertaken by NICE

    Numerical calculations of a high brilliance synchrotron source and on issues with characterizing strong radiation damping effects in non-linear Thomson/Compton backscattering experiments

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    A number of theoretical calculations have studied the effect of radiation reaction forces on radiation distributions in strong field counter-propagating electron beam-laser interactions, but could these effects - including quantum corrections - be observed in interactions with realistic bunches and focusing fields, as is hoped in a number of soon to be proposed experiments? We present numerical calculations of the angularly resolved radiation spectrum from an electron bunch with parameters similar to those produced in laser wakefield acceleration experiments, interacting with an intense, ultrashort laser pulse. For our parameters, the effects of radiation damping on the angular distribution and energy distribution of \emph{photons} is not easily discernible for a "realistic" moderate emittance electron beam. However, experiments using such a counter-propagating beam-laser geometry should be able to measure such effects using current laser systems through measurement of the \emph{electron beam} properties. In addition, the brilliance of this source is very high, with peak spectral brilliance exceeding 102910^{29} photons\,s1^{-1}mm2^{-2}mrad2(0.1^{-2}(0.1% bandwidth)1)^{-1} with approximately 2% efficiency and with a peak energy of 10 MeV.Comment: 11 figures, 11 page

    Trust economics feasibility study

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    We believe that enterprises and other organisations currently lack sophisticated methods and tools to determine if and how IT changes should be introduced in an organisation, such that objective, measurable goals are met. This is especially true when dealing with security-related IT decisions. We report on a feasibility study, Trust Economics, conducted to demonstrate that such methodology can be developed. Assuming a deep understanding of the IT involved, the main components of our trust economics approach are: (i) assess the economic or financial impact of IT security solutions; (ii) determine how humans interact with or respond to IT security solutions; (iii) based on above, use probabilistic and stochastic modelling tools to analyse the consequences of IT security decisions. In the feasibility study we apply the trust economics methodology to address how enterprises should protect themselves against accidental or malicious misuse of USB memory sticks, an acute problem in many industries

    A Planetary Companion to gamma Cephei A

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    We report on the detection of a planetary companion in orbit around the primary star of the binary system γ\gamma Cephei. High precision radial velocity measurements using 4 independent data sets spanning the time interval 1981--2002 reveal long-lived residual radial velocity variations superimposed on the binary orbit that are coherent in phase and amplitude with a period or 2.48 years (906 days) and a semi-amplitude of 27.5 m s1^{-1}. We performed a careful analysis of our Ca II H & K S-index measurements, spectral line bisectors, and {\it Hipparcos} photometry. We found no significant variations in these quantities with the 906-d period. We also re-analyzed the Ca II λ\lambda8662 {\AA} measurements of Walker et al. (1992) which showed possible periodic variations with the ``planet'' period when first published. This analysis shows that periodic Ca II equivalent width variations were only present during 1986.5 -- 1992 and absent during 1981--1986.5. Furthermore, a refined period for the Ca II λ\lambda8662 {\AA} variations is 2.14 yrs, significantly less than residual radial velocity period. The most likely explanation of the residual radial velocity variations is a planetary mass companion with MM sin ii = 1.7 MJupiterM_{Jupiter} and an orbital semi-major axis of a2a_2 == 2.13 AU. This supports the planet hypothesis for the residual radial velocity variations for γ\gamma Cep first suggested by Walker et al. (1992). With an estimated binary orbital period of 57 years γ\gamma Cep is the shortest period binary system in which an extrasolar planet has been found. This system may provide insights into the relationship between planetary and binary star formation.Comment: 19 pages, 15 figures, accepted in Ap. J. Includes additional data and improved orbital solutio

    How Do Quantitative And Qualitative Factors Influence The Selection Of Comparable, Competitive, And Aspirant Groups Under The Proposed AACSB Accreditation Maintenance Process?

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    The AACSB Blue Ribbon Committee on Accreditation Quality was “formed to do a thorough review of AACSB International's accreditation standards and procedures and to propose changes appropriate for global quality leadership in the next decade...” Within the proposal from the Blue Ribbon Committee is a change from a reaffirmation process with a site visit every ten years to a maintenance program resulting in a team visit in the sixth year of the cycle. Under the old standards applicants were required to submit “to the appropriate accreditation committee chair, in care of the AACSB International office, five nominations for each team role; i.e., five names for chair, five names for advisor, five for member, and if accounting accreditation were applicable, five names for vice-chair and five names for accounting advisor.” The proposed standards include a team selection process whereby the “applicant submits three comparison groups selected from members of the Accreditation Council... AACSB International will develop an on-line system to assist the applicant to identify potential comparison schools, officially select schools for each comparison group, and continuously maintain comparison group listings in an AACSB International database. Some information is currently available. The on-line service, www.aacsb.edu/knowledgeservices, offers advanced search functions that produce institution lists based on optionally selected criteria.” This AACSB provided information as well as information from other sources constitutes the basis for the recommended comparison group selection process
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