445 research outputs found

    A search for radiative neutrino decay from supernovae

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    This document presents the data analysis procedures proposed for use with the COMPTEL instrument aboard the Compton Gamma Ray Observatory (GRO) in the search for radiative neutrino decay from supernovae. The proposed analysis methodology is an extension of a standard procedure used by the COMPTEL team in searching for a variety of source types. We have applied the procedures to a set of simulated data to demonstrate the feasibility of the method to this project

    Determination of Neutrino Mass Hierarchy and Theta_13 with a Remote Detector of Reactor Antineutrinos

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    We describe a method for determining the hierarchy of the neutrino mass spectrum and theta_13 through remote detection of antineutrinos from a nuclear reactor. This method utilizing a single, 10-kt scintillating liquid detector at a distance of 50-64 kilometers from the reactor complex measures mass-squared differences involving nu_3 with a one (ten) year exposure provided sin2(2theta_13)>0.05 (0.02). Our technique applies the Fourier transform to the event rate as a function of neutrino flight distance over energy. Sweeping over a relevant range of delta-m2 resolves separate spectral peaks for delta-m2_31 and delta-m2_32. For normal (inverted) hierarchy the absolute value of delta-m2_31 is greater (lesser) than the absolute value of delta-m2_32. This robust method requires a detector energy resolution of 3.5% divided by the square root of the scintillation energy.Comment: 6 pages, 7 figures, note added to original paper submitted 12 December 200

    A program of correlated observations using the EGRET instrument on GRO and the IMB neutrino detector

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    A reliable, real-time supernova monitoring system was devised using the IMB neutrino detector to serve as an 'early-warning' system for EGRET and other instruments on GRO. New methods and software were developed to allow the IMB monitoring computer in Cleveland to: recognize that a trigger burst had occurred; make a judgement on whether the burst was spurrious or an actual supernova; prepare brief summary files and 'quick-look' data so that a final disposition could be made by a trained scientist; and contact the 'watch' scientist via personal beeper in Baton Rouge. This system ran from Dec. 1990 to Apr. 1991, when the neutrino detector failed for unrelated reasons. In addition to the supernova system, high-energy neutrino data was prepared and formatted for comparison with EGRET gamma-ray data

    Anomalous TWTA output power spikes and their effect on a digital satellite communications system

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    Several 30 GHz, 60 W traveling wave tube amplifiers (TWTA) were manufactured for the NASA Lewis Research Center's High Burst Rate Link Evaluation Terminal Project. An unusual operating problem characterized by anomalous nonperiodic output power spikes, common to all of the TWTAs proved during testing to significantly affect the performance of a digitally-modulated data transmission test system. Modifications made to the TWTAs significantly curtailed the problem and allowed acceptable system performance to be obtained. This paper presents a discussion of the TWTA output power spike problem, possible causes of the problem, and the solutions implemented by the manufacturer which improved the TWTA performance to an acceptable level. The results of the testing done at NASA Lewis on the TWTAs both before and after the improvement made by Hughes are presented, and the effects of the output power spikes on the performance of the test system are discussed

    Facility for the evaluation of space communications and related systems

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    NASA Lewis Research Center's Communications Projects Branch has developed a facility for the evaluation of space communications systems and related types of systems, called the Advanced Space Communications (ASC) Laboratory. The ASC Lab includes instrumentation, testbed hardware, and experiment control and monitor software for the evaluation of components, subsystems, systems, and networks. The ASC lab has capabilities to perform radiofrequency (RF), microwave, and millimeter-wave characterizations as well as measurements using low, medium, or high data rate digital signals. In addition to laboratory measurements, the ASC Lab also includes integrated satellite ground terminals allowing experimentation and measurements accessing operational satellites through real space links

    Palmitoylation of Desmoglein 2 Is a Regulator of Assembly Dynamics and Protein Turnover.

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    Desmosomes are prominent adhesive junctions present between many epithelial cells as well as cardiomyocytes. The mechanisms controlling desmosome assembly and remodeling in epithelial and cardiac tissue are poorly understood. We recently identified protein palmitoylation as a mechanism regulating desmosome dynamics. In this study, we have focused on the palmitoylation of the desmosomal cadherin desmoglein-2 (Dsg2) and characterized the role that palmitoylation of Dsg2 plays in its localization and stability in cultured cells. We identified two cysteine residues in the juxtamembrane (intracellular anchor) domain of Dsg2 that, when mutated, eliminate its palmitoylation. These cysteine residues are conserved in all four desmoglein family members. Although mutant Dsg2 localizes to endogenous desmosomes, there is a significant delay in its incorporation into junctions, and the mutant is also present in a cytoplasmic pool. Triton X-100 solubility assays demonstrate that mutant Dsg2 is more soluble than wild-type protein. Interestingly, trafficking of the mutant Dsg2 to the cell surface was delayed, and a pool of the non-palmitoylated Dsg2 co-localized with lysosomal markers. Taken together, these data suggest that palmitoylation of Dsg2 regulates protein transport to the plasma membrane. Modulation of the palmitoylation status of desmosomal cadherins can affect desmosome dynamics

    Incidence of physician-diagnosed osteoarthritis among active duty United States military service members

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    The article of record as published may be found at http://dx.DOI.org/10.1002/art.30498To examine the incidence of osteoarthritis and the influence of demographic and occupational factors associated with this condition among active duty US service members between 1999 and 2008
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