8,623 research outputs found

    Reducing the complexity of NASA's space communications infrastructure

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    This report describes the range of activities performed during the annual reporting period in support of the NASA Code O Success Team - Lifecycle Effectiveness for Strategic Success (COST LESS) team. The overall goal of the COST LESS team is to redefine success in a constrained fiscal environment and reduce the cost of success for end-to-end mission operations. This goal is more encompassing than the original proposal made to NASA for reducing complexity of NASA's Space Communications Infrastructure. The COST LESS team approach for reengineering the space operations infrastructure has a focus on reversing the trend of engineering special solutions to similar problems

    Description and calibration of the Langley Hypersonic CF4 tunnel: A facility for simulating low gamma flow as occurs for a real gas

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    The Langley Hypersonic CF4 Tunnel is a Mach 6 facility which simulates an important aspect of dissociative real-gas phenomena associated with the reentry of blunt vehicles, i.e., the decrease in the ratio of specific heats (gamma) that occurs within the shock layer of the vehicle. A general description of this facility is presented along with a discussion of the basic components, instrumentation, and operating procedure. Pitot-pressure surveys were made at the nozzle exit and downstream of the exit for reservoir temperatures from 1020 to 1495 R and reservoir pressures from 1000 to 2550 psia. A uniform test core having a diameter of circa 11 in. (0.55 times the nozzle-exit diameter) exists at the maximum value of reservoir pressure and temperature. The corresponding free-stream Mach number is 5.9, the unit Reynolds number is 4 x 10 to the 5th power per foot, the ratio of specific heats immediately behind a normal shock is 1.10, and the normal-shock density ratio is 12.6. When the facility is operated at reservoir temperatures below 1440 R, irregularities occur in the pitot-pressure profile within a small region about the nozzle centerline. These variations in pitot pressure indicate the existence of flow distrubances originating in the upstream region of the nozzle. This necessitates testing models off centerline in the uniform flow between the centerline region and either the nozzle boundary layer or the lip shock originating at the nozzle exit. Samples of data obtained in this facility with various models are presented to illustrate the effect of gamma on flow conditions about the model and the importance of knowing the magnitude of this effect

    Elevated cerebral spinal fluid biomarkers in children with mucopolysaccharidosis I-H.

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    Mucopolysaccharidosis (MPS) type-IH is a lysosomal storage disease that results from mutations in the IDUA gene causing the accumulation of glycosaminoglycans (GAGs). Historically, children with the severe phenotype, MPS-IH (Hurler syndrome) develop progressive neurodegeneration with death in the first decade due to cardio-pulmonary complications. New data suggest that inflammation may play a role in MPS pathophysiology. To date there is almost no information on the pathophysiologic changes within the cerebral spinal fluid (CSF) of these patients. We evaluated the CSF of 25 consecutive patients with MPS-IH. While CSF glucose and total protein were within the normal range, we found a significantly mean elevated CSF opening pressure at 24 cm H2O (range 14-37 cm H2O). We observed a 3-fold elevation in CSF heparan sulfate and a 3-8 fold increase in MPS-IH specific non-reducing ends, I0S0 and I0S6. Cytokine analyses in CSF of children with MPS-IH showed significantly elevated inflammatory markers including: MCP-1 SDF-1a, IL-Ra, MIP-1b, IL-8, and VEGF in comparison to unaffected children. This is the largest report of CSF characteristics in children with MPS-IH. Identification of key biomarkers may provide further insight into the inflammatory-mediated mechanisms related to MPS diseases and perhaps lead to improved targeted therapies

    Optimal 2,3-Trees

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    The 2,3-trees that are optimal in the sense of having minimal expected number of nodes visited per access are characterized in terms of their “profiles”. The characterization leads directly to a linear-time algorithm for constructing a K-key optimal 2,3-tree for a sorted list of K keys. A number of results are derived that demonstrate how different in structure these optimal 2,3-trees are from their “average” cousins

    Suzaku Observations of the Black Hole H1743-322 in Outburst

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    We observed the Galactic black hole candidate H1743-322 with Suzaku for approximately 32 ksec, while the source was in a low/hard state during its 2008 outburst. We collected and analyzed the data with the HXD/PIN, HXD/GSO and XIS cameras spanning the energy range from 0.7-200 keV. Fits to the spectra with simple models fail to detect narrow Fe XXV and Fe XXVI absorption lines, with 90% confidence upper limits of 3.5 eV and 2.5 eV on the equivalent width, respectively. These limits are commensurate with those in the very high state, but are well below the equivalent widths of lines detected in the high/soft state, suggesting that disk winds are partially state-dependent. We discuss these results in the context of previous detections of ionized Fe absorption lines in H1743-322 and connections to winds and jets in accreting systems. Additionally, we report the possible detection of disk reflection features, including an Fe K emission line.Comment: 16 pages, 4 figures, 4 tables. Accepted for publication in ApJ
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