1,709 research outputs found

    The LSND and MiniBooNE Oscillation Searches at High Δm2\Delta m^2

    Get PDF
    This paper reviews the results of the LSND and MiniBooNE experiments. The primary goal of each experiment was to effect sensitive searches for neutrino oscillations in the mass region with Δm2∼1\Delta m^2 \sim 1 eV2^2. The two experiments are complementary, and so the comparison of results can bring additional information with respect to models with sterile neutrinos. Both experiments obtained evidence for νˉμ→νˉe\bar \nu_\mu \rightarrow \bar \nu_e oscillations, and MiniBooNE also observed a νμ→νe\nu_\mu \rightarrow \nu_e excess. In this paper, we review the design, analysis, and results from these experiments. We then consider the results within the global context of sterile neutrino oscillation models. The final data sets require a more extended model than the simple single sterile neutrino model imagined at the time that LSND drew to a close and MiniBooNE began. We show that there are apparent incompatibilities between data sets in models with two sterile neutrinos. However, these incompatibilities may be explained with variations within the systematic error. Overall, models with two (or three) sterile neutrinos seem to succeed in fitting the global data, and they make interesting predictions for future experiments.Comment: Posted with permission from the Annual Review of Nuclear and Particle Science, Volume 63. \c{opyright} 2013 by Annual Reviews, http://www.annualreviews.or

    Extravehicular activities limitations study. Volume 1: Physiological limitations to extravehicular activity in space

    Get PDF
    This report contains the results of a comprehensive literature search on physiological aspects of EVA. Specifically, the topics covered are: (1) Oxygen levels; (2) Optimum EVA work; (3) Food and Water; (4) Carbon dioxide levels; (5) Repetitive decompressions; (6) Thermal, and (7) Urine collection. The literature was assessed on each of these topics, followed by statements on conclusions and recommended future research needs

    Effect of Rotor- and Stator-Blade Modifications on Surge Performance of an 11-Stage Axial-Flow Compressor. I - Original Production Compressor of XJ40-WE-6 Engine

    Get PDF
    An investigation to increase the compressor surge-limit pressure ratio of the XJ40-WE-6 turbojet engine at high equivalent speeds was conducted at the NACA Lewis altitude wind tunnel. This report evaluates the compressor modifications which were restricted to (1) twisting rotor blades (in place) to change blade section angles and (2) inserting new stator diaphragms with different blade angles. Such configuration changes could be incorporated quickly and easily in existing engines at overhaul depots. It was found that slight improvements in the compressor surge limit were possible by compressor blade adjustment. However, some of the modifications also reduced the engine air flow and hence penalized the thrust. The use of a mixer assembly at the compressor outlet improved the surge limit with no appreciable thrust penalty

    Applying Formal Verification Methods to Pure Rule-Based Programs

    Get PDF
    Reliability, defined as the guarantee that a program satisfies its specifications, is an important aspect of many applications for which rule-based expert systems are suited. Verification refer to the process used to determine the reliability of the rule-based program. Because past approaches to verification are informal, guarantees of reliability cannot fully be made without severely restricting the system. On the other hand, by constructing formal specifications for a program and showing the program satisfies those specifications, guarantees of reliability can be made. This paper presents an assertional approach to the verification of rule-based programs. The proof logical needed for verification is adopted from one already in use by researchers in concurrent programming. The approach involves using a language called Swarm, and requires one to express program specifications as assertions over the Swarm representation of the program. Among models the employ rule-based notation, Swarm is the first to have an axiomatic proof logic

    Bili Inhibits Wnt/β-Catenin Signaling by Regulating the Recruitment of Axin to LRP6

    Get PDF
    BACKGROUND: Insights into how the Frizzled/LRP6 receptor complex receives, transduces and terminates Wnt signals will enhance our understanding of the control of the Wnt/ss-catenin pathway. METHODOLOGY/PRINCIPAL FINDINGS: In pursuit of such insights, we performed a genome-wide RNAi screen in Drosophila cells expressing an activated form of LRP6 and a beta-catenin-responsive reporter. This screen resulted in the identification of Bili, a Band4.1-domain containing protein, as a negative regulator of Wnt/beta-catenin signaling. We found that the expression of Bili in Drosophila embryos and larval imaginal discs significantly overlaps with the expression of Wingless (Wg), the Drosophila Wnt ortholog, which is consistent with a potential function for Bili in the Wg pathway. We then tested the functions of Bili in both invertebrate and vertebrate animal model systems. Loss-of-function studies in Drosophila and zebrafish embryos, as well as human cultured cells, demonstrate that Bili is an evolutionarily conserved antagonist of Wnt/beta-catenin signaling. Mechanistically, we found that Bili exerts its antagonistic effects by inhibiting the recruitment of AXIN to LRP6 required during pathway activation. CONCLUSIONS: These studies identify Bili as an evolutionarily conserved negative regulator of the Wnt/beta-catenin pathway

    Book Reviews

    Get PDF
    • …
    corecore