157 research outputs found

    An inexpensive vehicle speed detector

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    Low-power minicomputer can plug into automobile cigarette lighter. It measures time it takes observed car to travel premeasured distance and provides immediate readout of speed. Potentially, detector could be manufactured for less than $200 per unit and would have very low maintenance cost

    Technique for improving hydrodynamic gyro bearings

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    Conical or spherical, spirally grooved grease bearings have an inclined surface which is machined inboard of the grooved surface. The indentation and inclined surface provide a reservoir for forced out lubricant, and when rotation begins, centrifugal force returns the lubricant to the grooved area

    A simple dead-reckoning navigational system

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    Simple navigation system is designed for vehicles operating in remote locations where it is not feasible to transport extensive equipment. System consists of four main components: directional gyrocompass to establish inertial direction; odometer to measure distance; signal processor to combine measured distance and direction; and sun compass to determine initial direction

    Paid Summer Research Opportunities with the Louisiana Biomedical Research Network

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    The Louisiana Biomedical Research Network Summer Research Program provides undergraduate and graduate students 4000to4000 to 6000 in support, including housing if needed, for summer research with LBRN investigators located at various institutions across the state. This presentation will summarize the program and the application process. Additional details can be found at: https://lbrn.lsu.edu/summer-research-program.htm

    Film calibration for the Skylab/ATM S-056 X-ray telescope

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    The sensitometry and film calibration effort for the Skylab/ATM S-056 X-ray telescope is summarized. The apparatus and procedures used are described together with the two types of flight film used, Kodak SO-212 and SO-242. The sensitometry and processing of the flight film are discussed, and the results are presented in the form of the characteristic curves and related data. The use of copy films is also discussed

    A Small-scale Wave Tank For Living Shoreline Extension And Outreach

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    Hardened structures, such as bulkheads and seawalls, are currently the primary choice of shoreline protection for waterfront property owners. However, hardened shorelines are known to enhance erosion and often promote the loss of intertidal habitat. Living shorelines are a collection of environmentally friendly construction techniques that serve as an alternative to hardened shorelines through the incorporation of natural materials, such as native plants. To enhance extension and outreach efforts related to the promotion of living shorelines, we created a small-scale, hands-on wave tank that demonstrates the benefits of natural and living shorelines relative to hardened structures. This interactive tool allows the audience to view the differences between natural, living, and hardened shorelines for both aesthetics and wave energy reduction

    ZFOURGE: Using Composite Spectral Energy Distributions to Characterize Galaxy Populations at 1<z<4

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    We investigate the properties of galaxies as they shut off star formation over the 4 billion years surrounding peak cosmic star formation. To do this we categorize 7000\sim7000 galaxies from 1<z<41<z<4 into 9090 groups based on the shape of their spectral energy distributions (SEDs) and build composite SEDs with R50R\sim 50 resolution. These composite SEDs show a variety of spectral shapes and also show trends in parameters such as color, mass, star formation rate, and emission line equivalent width. Using emission line equivalent widths and strength of the 4000\AA\ break, D(4000)D(4000), we categorize the composite SEDs into five classes: extreme emission line, star-forming, transitioning, post-starburst, and quiescent galaxies. The transitioning population of galaxies show modest Hα\alpha emission (EWREST40EW_{\rm REST}\sim40\AA) compared to more typical star-forming composite SEDs at log10(M/M)10.5\log_{10}(M/M_\odot)\sim10.5 (EWREST80EW_{\rm REST}\sim80\AA). Together with their smaller sizes (3 kpc vs. 4 kpc) and higher S\'ersic indices (2.7 vs. 1.5), this indicates that morphological changes initiate before the cessation of star formation. The transitional group shows a strong increase of over one dex in number density from z3z\sim3 to z1z\sim1, similar to the growth in the quiescent population, while post-starburst galaxies become rarer at z1.5z\lesssim1.5. We calculate average quenching timescales of 1.6 Gyr at z1.5z\sim1.5 and 0.9 Gyr at z2.5z\sim2.5 and conclude that a fast quenching mechanism producing post-starbursts dominated the quenching of galaxies at early times, while a slower process has become more common since z2z\sim2.Comment: Accepted for publication in The Astrophysical Journa

    Measurement of the half-life of the T=12\frac{1}{2} mirror decay of 19^{19}Ne and its implication on physics beyond the standard model

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    The 12+12+\frac{1}{2}^+ \rightarrow \frac{1}{2}^+ superallowed mixed mirror decay of 19^{19}Ne to 19^{19}F is excellently suited for high precision studies of the weak interaction. However, there is some disagreement on the value of the half-life. In a new measurement we have determined this quantity to be T1/2T_{1/2} = 17.2832±0.0051(stat)17.2832 \pm 0.0051_{(stat)} ±0.0066(sys)\pm 0.0066_{(sys)} s, which differs from the previous world average by 3 standard deviations. The impact of this measurement on limits for physics beyond the standard model such as the presence of tensor currents is discussed.Comment: 5 pages, 3 figures, 1 tabl

    Search for the Neutron Decay n\rightarrow X+γ\gamma where X is a dark matter particle

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    In a recent paper submitted to Physical Review Letters, Fornal and Grinstein have suggested that the discrepancy between two different methods of neutron lifetime measurements, the beam and bottle methods can be explained by a previously unobserved dark matter decay mode, n\rightarrow X+γ\gamma where X is a dark matter particle. We have performed a search for this decay mode over the allowed range of energies of the monoenergetic gamma ray for X to be a dark matter particle. We exclude the possibility of a sufficiently strong branch to explain the lifetime discrepancy with greater than 4 sigma confidence.Comment: 6 pages 3 figure
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