1,199 research outputs found

    CARS Temperature Measurements in a Hypersonic Propulsion Test Facility

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    Nonintrusive diagnostic measurements were performed in the supersonic reacting flow of the Hypersonic Propulsion Test Cell 2 at NASA-Langley. A Coherent Anti-stokes Raman Spectroscopy (CARS) system was assembled specifically for the test cell environment. System design considerations were: (1) test cell noise and vibration; (2) contamination from flow field or atmospheric borne dust; (3) unwanted laser or electrically induced combustion (inside or outside the duct); (4) efficient signal collection; (5) signal splitting to span the wide dynamic range present throughout the flow field; (6) movement of the sampling volume in the flow; and (7) modification of the scramjet model duct to permit optical access to the reacting flow with the CARS system. The flow in the duct was a nominal Mach 2 flow with static pressure near one atmosphere. A single perpendicular injector introduced hydrogen into the flow behind a rearward facing step. CARS data was obtained in three planes downstream of the injection region. At least 20 CARS data points were collected at each of the regularly spaced sampling locations in each data plane. Contour plots of scramjet combustor static temperature in a reacting flow region are presented

    The cost-effectiveness of Cochlear implants in Swedish adults.

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    BackgroundResearch has shown unilateral cochlear implants (CIs) significantly improve clinical outcomes and quality of life in adults. However, only 13% of eligible Swedish adults currently use a unilateral CI. The objective was to estimate the cost-effectiveness of unilateral CIs compared to a hearing aid for Swedish adults with severe to profound hearing loss.MethodsA Markov model with a lifetime horizon and six-month cycle length was developed to estimate the benefits and costs of unilateral CIs from the Swedish health system perspective. A treatment pathway was developed through consultation with clinical experts to estimate resource use and costs. Unit costs were derived from the Swedish National Board of Health and Welfare and the Swedish Association of Local Authorities and Regions. Health outcomes were reported in terms of Quality Adjusted Life Years (QALYs).ResultsUnilateral CIs for Swedish adults with severe to profound hearing loss are likely to be deemed cost-effective when compared to a hearing aid (SEK 140,474 per QALY gained). The results were most sensitive to the age when patients are implanted with a CI and the proportion of patients eligible for CIs after triage.ConclusionsAn increase in the prevalence of Swedish adults with severe to profound hearing loss is expected as the population ages. Earlier implantation of unilateral CIs improves the cost-effectiveness among people eligible for CIs. Unilateral CIs are an efficacious and cost-effective option to improve hearing and quality of life in Swedish adults with severe to profound hearing loss

    Muon Catalyzed Fusion in 3 K Solid Deuterium

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    Muon catalyzed fusion in deuterium has traditionally been studied in gaseous and liquid targets. The TRIUMF solid-hydrogen-layer target system has been used to study the fusion reaction rates in the solid phase of D_2 at a target temperature of 3 K. Products of two distinct branches of the reaction were observed; neutrons by a liquid organic scintillator, and protons by a silicon detector located inside the target system. The effective molecular formation rate from the upper hyperfine state of μd\mu d and the hyperfine transition rate have been measured: λ~(3/2)=2.71(7)stat.(32)syst.μ/s\tilde{\lambda}_(3/2)=2.71(7)_{stat.}(32)_{syst.} \mu/s, and λ~(3/2)(1/2)=34.2(8)stat.(1)syst.μ/s\tilde{\lambda}_{(3/2)(1/2)} =34.2(8)_{stat.}(1)_{syst.} \mu /s. The molecular formation rate is consistent with other recent measurements, but not with the theory for isolated molecules. The discrepancy may be due to incomplete thermalization, an effect which was investigated by Monte Carlo calculations. Information on branching ratio parameters for the s and p wave d+d nuclear interaction has been extracted.Comment: 19 pages, 11 figures, submitted to PRA Feb 20, 199

    Safety, the Preface Paradox and Possible Worlds Semantics

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    This paper contains an argument to the effect that possible worlds semantics renders semantic knowledge impossible, no matter what ontological interpretation is given to possible worlds. The essential contention made is that possible worlds semantic knowledge is unsafe and this is shown by a parallel with the preface paradox

    Measurement of the Resonant dμtd\mu t Molecular Formation Rate in Solid HD

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    Measurements of muon-catalyzed dt fusion (dμt4He+n+μd\mu t \to ^4He+n+\mu^-) in solid HD have been performed. The theory describing the energy dependent resonant molecular formation rate for the reaction μt\mu t + HD [(dμt)pee]\to [(d\mu t)pee]^* is compared to experimental results in a pure solid HD target. Constraints on the rates are inferred through the use of a Monte Carlo model developed specifically for the experiment. From the time-of- flight analysis of fusion events in 16 and 37 μgcm2\mu g\cdot cm^{-2} targets, an average formation rate consistent with 0.897±\pm(0.046)stat±_{stat}\pm (0.166)syst_{syst} times the theoretical prediction was obtained.Comment: 4 pages, 5 figure

    A new implementation of high-throughput five-dimensional clone pooling strategy for BAC library screening

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    <p>Abstract</p> <p>Background</p> <p>A five-dimensional (5-D) clone pooling strategy for screening of bacterial artificial chromosome (BAC) clones with molecular markers utilizing highly-parallel Illumina GoldenGate assays and PCR facilitates high-throughput BAC clone and BAC contig anchoring on a genetic map. However, this strategy occasionally needs manual PCR to deconvolute pools and identify truly positive clones.</p> <p>Results</p> <p>A new implementation is reported here for our previously reported clone pooling strategy. Row and column pools of BAC clones are divided into sub-pools with 1~2× genome coverage. All BAC pools are screened with Illumina's GoldenGate assay and the BAC pools are deconvoluted to identify individual positive clones. Putative positive BAC clones are then further analyzed to find positive clones on the basis of them being neighbours in a contig. An exhaustive search or brute force algorithm was designed for this deconvolution and integrated into a newly developed software tool, FPCBrowser, for analyzing clone pooling data. This algorithm was used with empirical data for 55 Illumina GoldenGate SNP assays detecting SNP markers mapped on <it>Aegilops tauschii </it>chromosome 2D and <it>Ae. tauschii </it>contig maps. Clones in single contigs were successfully assigned to 48 (87%) specific SNP markers on the map with 91% precision.</p> <p>Conclusion</p> <p>A new implementation of 5-D BAC clone pooling strategy employing both GoldenGate assay screening and assembled BAC contigs is shown here to be a high-throughput, low cost, rapid, and feasible approach to screening BAC libraries and anchoring BAC clones and contigs on genetic maps. The software FPCBrowser with the integrated clone deconvolution algorithm has been developed and is downloadable at <url>http://avena.pw.usda.gov/wheatD/fpcbrowser.shtml</url>.</p
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