31,331 research outputs found

    Spacelab software development and integration concepts study report, volume 1

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    The proposed software guidelines to be followed by the European Space Research Organization in the development of software for the Spacelab being developed for use as a payload for the space shuttle are documented. Concepts, techniques, and tools needed to assure the success of a programming project are defined as they relate to operation of the data management subsystem, support of experiments and space applications, use with ground support equipment, and for integration testing

    Space station integrated propulsion and fluid systems study

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    This Databook addresses the integration of fluid systems of the Space Station program. It includes a catalog of components required for the Space Station elements fluid systems and information on potential hardware commonality. The components catalog is in four parts. The first part lists the components defined for all the fluid systems identified in EP 2.1, Space Station Program Fluid Systems Configuration Databook. The components are cross-referenced in three sections. Section 2.1 lists the components by the fluid system in which they are used. Section 2.2 lists the components by type. Section 2.3 lists by the type of fluid media handled by the component. The next part of the catalog provides a description of the individual component. This section (2.4) is made up of data retrieved from Martin Marietta Denver Aerospace component data base. The third part is an assessment of propulsion hardware technology requirements. Section 2.5 lists components identified during the study as requiring development prior to flight qualification. Finally, Section 2.6 presents the results of the evaluation of commonality between components. The specific requirements of each component have been reviewed and duplication eliminated

    Space station integrated propulsion and fluid system study: Fluid systems configuration databook

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    This databook contains fluid system requirements and system descriptions for Space Station program elements including the United States and International modules, integrated fluid systems, attached payloads, fluid servicers and vehicle accommodation facilities. Separate sections are devoted to each of the program elements and include a discussion of the overall system requirements, specific fluid systems requirements and systems descriptions. The systems descriptions contain configurations, fluid inventory data and component lists. In addition, a list of information sources is referenced at the end of each section

    Interpretation of x-ray-absorption dichroism experiments

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    A rule is derived to use x-ray magnetic circular dichroism spectra to extract the magnetic moment of the conduction-band states with j= l -1/2 separately from those with j= l + 1/2 as a function of energy. This quantity is straightforward to determine from the electronic band structure. The rule is illustrated with an application to pure iron and to the random substitutional alloy Fe_{80}CO_{20}

    High Accuracy Fuel Flowmeter, Phase 1

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    Technology related to aircraft fuel mass - flowmeters was reviewed to determine what flowmeter types could provide 0.25%-of-point accuracy over a 50 to one range in flowrates. Three types were selected and were further analyzed to determine what problem areas prevented them from meeting the high accuracy requirement, and what the further development needs were for each. A dual-turbine volumetric flowmeter with densi-viscometer and microprocessor compensation was selected for its relative simplicity and fast response time. An angular momentum type with a motor-driven, spring-restrained turbine and viscosity shroud was selected for its direct mass-flow output. This concept also employed a turbine for fast response and a microcomputer for accurate viscosity compensation. The third concept employed a vortex precession volumetric flowmeter and was selected for its unobtrusive design. Like the turbine flowmeter, it uses a densi-viscometer and microprocessor for density correction and accurate viscosity compensation

    Five Principles for Vertical Merger Enforcement Policy

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    There seems to be consensus that the Department of Justice’s 1984 Vertical Merger Guidelines do not reflect either modern theoretical and empirical economic analysis or current agency enforcement policy. Yet widely divergent views of preferred enforcement policies have been expressed among agency enforcers and commentators. Based on our review of the relevant economic literature and our experience analyzing vertical mergers, we recommend that the enforcement agencies adopt five principles: (i) The agencies should consider and investigate the full range of potential anticompetitive harms when evaluating vertical mergers; (ii) The agencies should decline to presume that vertical mergers benefit competition on balance in the oligopoly markets that typically prompt agency review, nor set a higher evidentiary standard based on such a presumption; (iii) The agencies should evaluate claimed efficiencies resulting from vertical mergers as carefully and critically as they evaluate claimed efficiencies resulting from horizontal mergers, and require the merging parties to show that the efficiencies are verifiable, merger-specific and sufficient to reverse the potential anticompetitive effects; (iv) The agencies should decline to adopt a safe harbor for vertical mergers, even if rebuttable, except perhaps when both firms compete in unconcentrated markets; (v) The agencies should consider adopting rebuttable anticompetitive presumptions that a vertical merger harms competition when certain factual predicates are satisfied. We do not intend these presumptions to describe all the ways by which vertical mergers can harm competition, so the agencies should continue to investigate vertical mergers that raise concerns about input and customer foreclosure, loss of a disruptive or maverick firm, evasion of rate regulation or other threats to competition, even if the specific factual predicates of the presumptions are not satisfied

    Screening of a HUVEC cDNA library with transplant-associated coronary artery disease sera identifies RPL7 as a candidate autoantigen associated with this disease.

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    A HUVEC cDNA library was screened with sera from two patients who had developed transplant-associated coronary artery disease (TxCAD) following cardiac transplantation. A total of six positive clones were isolated from a primary screen of 40 000 genes. Subsequent DNA sequence analysis identified these to be lysyl tRNA synthetase, ribosomal protein L7, ribosomal protein L9, beta transducin and TANK. Another gene whose product could not be identified showed homology to a human cDNA clone (DKFZp566M063) derived from fetal kidney. Full-length constructs of selected genes were expressed as his-tag recombinant fusion proteins and used to screen a wider patient base by ELISA to determine prevalence and association with TxCAD. Of these ribosomal protein L7 showed the highest prevalence (55.6%) with TxCAD sera compared to 10% non-CAD

    Cost-reflective pricing: empirical insights into irrigators’ preferences for water tariffs

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    © 2017 The Authors. The Australian Journal of Agricultural and Resource Economics published by John Wiley & Sons Australia, Ltd on behalf of Australasian Agricultural and Resource Economics Society Inc. Using prices to improve the efficiency with which water resources are allocated is now widely accepted in principle if somewhat difficult to achieve in practice. Whilst there are some technical difficulties associated with full-cost recovery in irrigation, the lack of political will to tackle reform remains a significant impediment. This article reports the results of an empirical investigation into farmers’ preferences for changes to water prices and tariff structures. We conclude that some of the preferences of farmers are conducive to price reform. We also find evidence that public subsidy of infrastructure in irrigation is not always aligned with the preferences of farmers

    The Heumann-Hotzel model for aging revisited

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    Since its proposition in 1995, the Heumann-Hotzel model has remained as an obscure model of biological aging. The main arguments used against it were its apparent inability to describe populations with many age intervals and its failure to prevent a population extinction when only deleterious mutations are present. We find that with a simple and minor change in the model these difficulties can be surmounted. Our numerical simulations show a plethora of interesting features: the catastrophic senescence, the Gompertz law and that postponing the reproduction increases the survival probability, as has already been experimentally confirmed for the Drosophila fly.Comment: 11 pages, 5 figures, to be published in Phys. Rev.
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