17,980 research outputs found

    Collaborative research on V/STOL control system/cockpit display tradeoffs under the NASA/MOD joint aeronautical program

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    Summarized here are activities that have taken place from 1979 to the present in a collaborative program between NASA Ames Research Center and the Royal Aerospace Establishment (now Defence Research Agency), Bedford on flight control system and cockpit display tradeoffs for low-speed and hover operations of future V/STOL aircraft. This program was created as Task 8A of the Joint Aeronautical Program between NASA in the United States and the Ministry of Defence (Procurement Executive) in the United Kingdom. The program was initiated based on a recognition by both parties of the strengths of the efforts of their counterparts and a desire to participate jointly in future simulation and flight experiments. In the ensuing years, teams of NASA and RAE engineers and pilots have participated in each other's simulation experiments to evaluate control and display concepts and define design requirements for research aircraft. Both organizations possess Harrier airframes that have undergone extensive modification to provide in-flight research capabilities in the subject areas. Both NASA and RAE have profited by exchanges of control/display concepts, design criteria, fabrication techniques, software development and validation, installation details, and ground and flight clearance techniques for their respective aircraft. This collaboration has permitted the two organizations to achieve jointly substantially more during the period than if they had worked independently. The two organizations are now entering the phase of flight research for the collaborative program as currently defined

    A National Dialogue on Health Information Technology and Privacy

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    Increasingly, government leaders recognize that solving the complex problems facing America today will require more than simply keeping citizens informed. Meeting challenges like rising health care costs, climate change and energy independence requires increased level of collaboration. Traditionally, government agencies have operated in silos -- separated not only from citizens, but from each other, as well. Nevertheless, some have begun to reach across and outside of government to access the collective brainpower of organizations, stakeholders and individuals.The National Dialogue on Health Information Technology and Privacy was one such initiative. It was conceived by leaders in government who sought to demonstrate that it is not only possible, but beneficial and economical, to engage openly and broadly on an issue that is both national in scope and deeply relevant to the everyday lives of citizens. The results of this first-of-its-kind online event are captured in this report, together with important lessons learned along the way.This report served as a call to action. On his first full day in office, President Obama put government on notice that this new, more collaborative model can no longer be confined to the efforts of early adopters. He called upon every executive department and agency to "harness new technology" and make government "transparent, participatory, and collaborative." Government is quickly transitioning to a new generation of managers and leaders, for whom online collaboration is not a new frontier but a fact of everyday life. We owe it to them -- and the citizens we serve -- to recognize and embrace the myriad tools available to fulfill the promise of good government in the 21st Century.Key FindingsThe Panel recommended that the Administration give stakeholders the opportunity to further participate in the discussion of heath IT and privacy through broader outreach and by helping the public to understand the value of a person-centered view of healthcare information technology

    VO2 Reserve and the Minimal Intensity for Improving Cardiorespiratory Fitness

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    Purpose: The American College of Sports Medicine has stated that aerobic: training needs to occur at a minimum threshold intensity of 50% VO2max for most healthy adults and at 40% VO2max for those with a very low initial fitness. Recently, the concept of VO2 reserve (% VO2R, i.e., a percentage of the difference between maximum and resting VO2 has been introduced for prescribing exercise intensity, This analysis was designed to determine the threshold intensity for improving cardiorespiratory fitness expressed as %VO2R units. Methods: Previous studies in healthy subjects (N = 18) that evaluated the result, of training at low-to-moderate intensities (i.e., less than or equal to 60% VO2max) were identified. The original studies described the intensity of exercise variously as %VO2max, %HRR, %HRmax or as a specific HR value. In each case, the intensity was translated into %VO2R units. Results: Exercise training intensities below approximately 45% VO2R were consistently ineffective at increasing VO2max in studies that used subjects with mean initial VO2max values \u3e 40 mL.min-1 kg-1. In studies using subjects with mean initial VO2max values \u3c 40 mL.min-1.kg-1, no intensity A as found to be ineffective. For this latter group of subjects, the lowest intensities examined A ere approximately 30% VO2R. Conclusion: Although evidence for a threshold intensity was not strong, this analysis of training studies support the use of 45% VO2R as a minimal effective training intensity for higher fit subjects and 30% VO2R for lower fit subjects

    Technical characteristics of the OmniTRACS: The first operation mobile Ku-band satellite communications system

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    The techinical characteristics of the OmniTRACS system are described. The system is the first operational mobile Ku-band satellite communications system and provides two-way message and position determination service to mobile terminals using existing Ku-band satellites. Interference to and from the system is minimized by the use of special spread-spectrum techniques, together with low power and low data rate transmissions

    A selected history of expectation bias in physics

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    The beliefs of physicists can bias their results towards their expectations in a number of ways. We survey a variety of historical cases of expectation bias in observations, experiments, and calculations.Comment: 6 pages, 2 figure

    Electron heating mechanisms in dual frequency capacitive discharges

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    We discuss electron heating mechanisms in the sheath regions of dual-frequency capacitive discharges, with the twin aims of identifying the dominant mechanisms and supplying closed-form expressions from which the heating power can be estimated. We show that the heating effect produced by either Ohmic or collisionless heating is much larger when the discharge is excited by a superposition of currents at two frequencies than if either current had acted alone. This coupling effect occurs because the lower frequency current, while not directly heating the electrons to any great extent, strongly affects the spatial structure of the discharge in the sheath regions

    Intrinsic thermal vibrations of suspended doubly clamped single-wall carbon nanotubes

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    We report the observation of thermally driven mechanical vibrations of suspended doubly clamped carbon nanotubes, grown by chemical vapor deposition (CVD). Several experimental procedures are used to suspend carbon nanotubes. The vibration is observed as a blurring in images taken with a scanning electron microscope. The measured vibration amplitudes are compared with a model based on linear continuum mechanics.Comment: pdf including figures, see: http://www.unibas.ch/phys-meso/Research/Papers/2003/NT-Thermal-Vibrations.pd

    Effect of Sequence on the Conformation of DNA Holliday Junctions

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    Structures of the DNA sequences d(CCGGCGCCGG) and d(CCAGTACbr5UGG) are presented here as four-way Holliday junctions in their compact stacked-X forms, with antiparallel alignment of the DNA strands. Thus, the ACC-trinucleotide motif, previously identified as important for stabilizing the junction, is now extended to PuCPy, where Pu is either an adenine or guanine, and Py is either a cytosine, 5-methylcytosine, or 5-bromouracil but not thymine nucleotide. We see that both sequence and base substituents affect the geometry of the junction in terms of the interduplex angle as well as the previously defined conformational variables, Jroll (the rotation of the stacked duplexes about their respective helical axis) and Jslide (the translational displacement of the stacked duplexes along their respective helical axis). The structures of the GCC and parent ACC containing junctions fall into a distinct conformational class that is relatively undistorted in terms of Jslide and Jroll, with interduplex angles of 40-43°. The substituted ACbr5U structure, however, is more akin to that of the distorted methylated ACm5C containing junction, with Jslide (g2.3 Å) and a similar Jroll (164°) opening the major groove-side of the junction, but shows a reduced interduplex angle. In contrast, the analogous d(CCAGTACTGG) sequence has to date been crystallized only as resolved B-DNA duplexes. This suggests that there is an electronic effect of substituents at the pyrimidine Py position on the stability of four-stranded junctions. The single-crystal structures presented here, therefore, show how sequence affects the detailed geometry, and subsequently, the associated stability and conformational dynamics of the Holliday junction

    Extraordinary sensitivity of the electronic structure and properties of single-walled carbon nanotubes to molecular charge-transfer

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    Interaction of single-walled carbon nanotubes with electron donor and acceptor molecules causes significant changes in the electronic and Raman spectra, the relative proportion of the metallic species increasing on electron donation through molecular charge transfer, as also verified by electrical resistivity measurements.Comment: 15 pages, 5 figurre

    Colour vision deficiency among students in Lagos State, Nigeria

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    Background: Congenital colour vision defects are x-linked inherited, non-progressive and untreatable disorders that describe poor colour discrimination.Objective: To determine the prevalence of congenital colour vision deficiency among students in Lagos, Nigeria.Methods: A school-based cross-sectional, cluster sample study was conducted to test the colour vision of 2326 primary and high school students. Inclusion criteria were Snellen VA 20/20 or better and absence of known ocular pathologies. Colour vision deficiency (CVD) was evaluated with the Richmond-HRR colour vision test plates.Results: There were 1014 (43.6%) males and 1312 (56.4%) females with a mean age of 13.40 ± 2.40 years (range = 7−22 years). The prevalence of CVD was 58 (2.5%), which was higher in males 49 (4.8%) than females 9 (0.7%). The prevalence of congenitalCVD was significantly associated with males (p = 0.00), but not with females (p = 0.22). Of the 58 cases of CVD, 17 (0.7%) had protan deficiency, 38 (1.6%) had deutan deficiency and three (0.1%) were unclassified.Conclusion: The prevalence of congenital CVD among students in Lagos is comparable to findings in other parts of Nigeria but differs from other parts of the country. These results strengthen the need to establish school vision screening.Keywords: Colour vision deficiency, Richmond-HRR, prevalence, red-green defects, Nigeria
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