24,114 research outputs found

    Shuttle Ground Operations Efficiencies/Technologies Study (SGOE/T). Volume 5: Technical Information Sheets (TIS)

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    The Technology Information Sheet was assembled in database format during Phase I. This document was designed to provide a repository for information pertaining to 144 Operations and Maintenance Instructions (OMI) controlled operations in the Orbiter Processing Facility (OPF), Vehicle Assembly Building (VAB), and PAD. It provides a way to accumulate information about required crew sizes, operations task time duration (serial and/or parallel), special Ground Support Equipment (GSE). required, and identification of a potential application of existing technology or the need for the development of a new technolgoy item

    Shuttle Ground Operations Efficiencies/Technologies (SGOE/T) study. Volume 2: Ground Operations evaluation

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    The Ground Operations Evaluation describes the breath and depth of the various study elements selected as a result of an operational analysis conducted during the early part of the study. Analysis techniques used for the evaluation are described in detail. Elements selected for further evaluation are identified; the results of the analysis documented; and a follow-on course of action recommended. The background and rationale for developing recommendations for the current Shuttle or for future programs is presented

    Shuttle Ground Operations Efficiencies/Technologies (SGOE/T) study. Volume 1: Executive summary

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    Methods and technolgoy were defined to reduce the overall operations cost of a major space program. Space Shuttle processing at Kennedy Space Center (KSC) was designed as the working model that would be the source of the operational information. Methods of improving efficiency of ground operations were assessed and technology elements that could reduce cost identified. Emphasis is on: (1) specific technology items and (2) management approaches required to develop and support efficient ground operations. Prime study results are to be recommendations on how to achieve more efficient operations and identification of existing or new technology that would make vehicle processing in both the current program and future programs more efficient and, therefore, less costly

    Effect of Concomitant 3-Hydroxy-3-Methyl-Glutaryl-CoA Reductase Inhibitor Therapy on Creatine Phosphokinase Levels and Mortality Among Patients Receiving Daptomycin: Retrospective Cohort Study.

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    IntroductionThe prescribing information for daptomycin recommends discontinuing statin therapy during receipt of daptomycin. The literature supporting this recommendation is sparse. The objectives of this study were to examine the impact of 3-hydroxy-3-methyl-glutaryl-CoA (HMG-CoA) reductase inhibitors (statins) on creatine phosphokinase (CPK) elevations and mortality among patients receiving daptomycin therapy.MethodsA retrospective cohort study was performed among daptomycin recipients in the Upstate New York Veterans' Healthcare Administration from September 15, 2003 to July 1, 2013. Inclusion criteria were: (1) daptomycin for ≥48 h, (2) availability of baseline CPK value and (3) >1 CPK level measurement taken while on therapy. The following were extracted from medical records: demographics, comorbidities, laboratory data, medication history (daptomycin, statins and concomitant drugs known to increase CPK), Acute Physiology and Chronic Health Evaluation (APACHE)-II score and vital status at 30 days. The exposure of interest was use of statins. The primary outcome was CPK elevation defined as a CPK value ≥3 times the upper limit of normal (ULN) if baseline CPK was normal, and ≥5 times ULN if baseline CPK was elevated. The secondary outcome was death within 30 days of commencing daptomycin.ResultsA total of 233 patients were included in this analysis. Among these patients, 53 received concomitant statin therapy. Most baseline clinical characteristics were similar between statin recipients and non-recipients. Five (2.1%) patients experienced a CPK elevation; 3/53 (5.7%) were statin recipients and 2/180 (1.1%) received daptomycin alone (p = 0.08). All patients with CPK elevations had normal baseline CPK values. No effect modification was observed by use of other concomitant medications known to increase CPK values. Death was observed more frequently among statin non-recipients (17.2%) than recipients (9.4%).ConclusionsAmong patients receiving daptomycin, no significant difference was observed in frequency of CPK elevation between statin recipients and non-recipients

    XLV. Osmotic pressure from the standpoint of the kinetic theory

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    The Bootstrap Approach to Predicting Airplane Flight Performance

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    The Bootstrap Approach (TBA) to fight performance is, for fixed-pitch propeller-driven airplanes, a set of simple formulas in nine aircraft parameters-four from brief flight tests-plus the variables of aircraft weight and air density. The formulas are derivable from the empirically supported linearity of the propeller polar. TBA outputs include five full-throttle or gliding V-speeds (Vx Vy Vm Vbg Vmd) and a common version of long range cruise speed (VLRC) as well as, for any air speed, thrust, drag, rate of climb (thereby service ceiling) or descent, and flight path angle. Knowledge of engine speed (RPM) and fuel consumption rate allows calculation of (partial-throttle) speeds Vbr for best range and Vbe for best endurance. An extension of TBA to airplanes with constant-speed propellers substitutes two different propeller parameters and suggests a general propeller chart. Though based on empirical graphs rather than formulas, this extension easily incorporates partial-throttle operation

    Predicting uncertainty in sediment transport and landscape evolution - the influence of initial surface conditions

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    © 2015. Numerical landscape evolution models were initially developed to examine natural catchment hydrology and geomorphology and have become a common tool to examine geomorphic behaviour over a range of time and space scales. These models all use a digital elevation model (DEM) as a representation of the landscape surface and a significant issue is the quality and resolution of this surface. Here we focus on how subtle perturbations or roughness on the DEM surface can produce alternative model results. This study is carried out by randomly varying the elevations of the DEM surface and examining the effect on sediment transport rates and geomorphology for a proposed rehabilitation design for a post-mining landscape using multiple landscape realisations with increasing magnitudes of random changes. We show that an increasing magnitude of random surface variability does not appear to have any significant effect on sediment transport over millennial time scales. However, the random surface variability greatly changes the temporal pattern or delivery of sediment output. A significant finding is that all simulations at the end of the 10,000 year modelled period are geomorphologically similar and present a geomorphological equifinality. However, the individual patterns of erosion and deposition were different for repeat simulations with a different sequence of random perturbations. The alternative positions of random perturbations strongly influence local patterns of hillslope erosion and evolution together with the pattern and behaviour of deposition. The findings demonstrate the complex feedbacks that occur even within a simple modelled system

    Letters to the Editor

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