30 research outputs found

    Propulsion system tests on a full scale Centaur vehicle to investigate 3-burn mission capability of the D-lT configuration

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    Propulsion system tests were conducted on a full scale Centaur vehicle to investigate system capability of the proposed D-lT configuration for a three-burn mission. This particular mission profile requires that the engines be capable of restarting and firing for a final maneuver after a 5-1/2-hour coast to synchronous orbit. The thermal conditioning requirements of the engine and propellant feed system components for engine start under these conditions were investigated. Performance data were also obtained on the D-lT type computer controlled propellant tank pressurization system. The test results demonstrated that the RL-10 engines on the Centaur vehicle could be started and run reliably after being thermally conditioned to predicted engine start conditions for a one, two and three burn mission. Investigation of the thermal margins also indicated that engine starts could be accomplished at the maximum predicted component temperature conditions with prestart durations less than planned for flight

    Coal and Climate Change

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    This overview adopts a critical social science perspective to examine the state of play and potential futures for coal in the context of climate change. It introduces key trends in coal consumption, production and trade, before appraising the relevant literature. Finding surprisingly little literature directly focussed on coal and climate change compared with related fields, it appraises existing work and highlights key areas for future work. In addition to established bodies of work on the situated politics of coal and the political economy of coal, new work calling for demand side policies to be supplemented with supply side policies highlights the increasing importance of how normative contestations drive debates over coal, suggesting that future work needs to engage not only much more directly with climate change as an issue, but particularly with the place of coal in a just transition. Because of coal’s mammoth contribution to climate change and the complex political economy which drives its production and consumption, it is likely that coal will remain at the centre of difficult questions about the relationship between climate action and development for some time

    FIRST ASTRONOMICAL IMAGES SHARPENED WITH ADAPTIVE OPTICS USING A SODIUM LASER GUIDE STAR M. Lloyd-Hart, J. R. P. Angel, T. D. Groesbeck, T. Martinez, B. P. Jacobsen, B. A. McLeod

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    Adaptive optics with a sodium resonance laser guide star was used at the Multiple Mirror Telescope (MMT) in 1996 April to image the core of the globular cluster M13 (NGC 6205). A 23 field was recorded in the K s -band with image resolution of 0.51, when the uncorrected resolution was 0.72. Global tilt, not sensed by the laser, was measured from the image motion of a star 35 from the center of the field. Despite this separation, the star profiles do not vary significantly across the image. Many more stars fainter than K s = 17.5 can be identified in the corrected image. The 0.5 imaging capability here demonstrated, though not reaching the performance of existing faster, higher-order systems with natural star wave-front sensors, is significant because it can be generally realized for very faint objects under normal observing conditions. This characteristic will carry over to higher order laser-based systems, making them very powerful. Our current 0.5 resolution is much larger than the d..

    Comparing Reported Dietary Supplement Intakes between Two 24-Hour Recall Methods: The Automated Self-Administered 24-Hour Dietary Assessment Tool and the Interview-Administered Automated Multiple Pass Method

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    BACKGROUND: The Automated Self-Administered 24-hour Dietary Assessment Tool (ASA24) includes a highly standardized multipass web-based recall that, like the Automated Multiple Pass Method (AMPM), captures detailed information about dietary intake using multiple probes and reminders to enhance recall of intakes. The primary distinction between ASA24 and AMPM is that the ASA24 user interface guides participants, thus removing the need for interviewers. OBJECTIVE: The objective of this study was to compare dietary supplement use reported on self-administered (ASA24-2011) vs interviewer-administered (AMPM) 24-hour recalls. DESIGN: The Food Reporting Comparison Study was an evaluation study designed to compare self-reported intakes captured using the self-administered ASA24 vs data collected via interviewer-administered AMPM recalls. Between 2010 and 2011, 1081 women and men were enrolled from three integrated health care systems that belong to the National Cancer Institute-funded Cancer Research Network: Security Health Plan Marshfield Clinic, Wisconsin; Henry Ford Health System, Michigan; and Kaiser Permanente Northern California, California. Quota sampling was used to ensure a balance of age, sex, and race/ethnicity. Participants were randomly assigned to four groups, and each group was asked to complete two dietary recalls: group 1, two ASA24s; group 2, two AMPMs; group 3, ASA24 first and AMPM second; and group 4, AMPM first and ASA24 second. Dietary supplements were coded using the 2007-2008 National Health and Nutrition Examination Survey Dietary Supplement Database. Analyses used the two one-sided tests, known as TOST, to assess equivalence of reported supplement use between methods. RESULTS: Complete 24-hour dietary recalls that included both dietary and supplement intake data were available for 1076 participants (507 men and 569 women). The proportions reporting supplement use via ASA24 and AMPM were 46% and 43%, respectively. These proportions were equivalent, with a small effect size of less than 20%. There were two exceptions in subgroup analyses: reported use among those 40 to 59 years of age and reported use by non-Hispanic black subjects were higher for ASA24 than AMPM. CONCLUSIONS: This study provides evidence that there is little difference in reported supplement use by mode of administration (ie, interview-administered vs self-administered recall)
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