722 research outputs found

    Analysis of fluorine addition to the vanguard first stage

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    The effect of adding fluorine to the Vanguard first-stage oxidant was anlyzed. An increase in specific impulse of 5.74 percent may be obtained with 30 percent fluorine. This increase, coupled with increased mass ratio due to greater oxidant density, gave up to 24.6-percent increase in first-stage burnout energy with 30 percent fluorine added. However, a change in tank configuration is required to accommodate the higher oxidant-fuel ratio necessary for peak specific impulse with fluorine addition

    X-ray Investigation of the Critical Exponent η in Argon

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    Measurements were made of the small-angle x-ray scattering intensity from argon near the critical point. After the scattering curves are corrected for all known effects except those resulting from irrelevant variables, a value of the critical exponent η=0.09±0.02 is obtained, while if a correction for the estimated effect of irrelevant variables is also made, η=0.03±0.03. The scattering data for argon therefore show that if irrelevant variables can be neglected, the critical exponent η for argon is in good agreement with the value obtained by Warkulwiz, Mozer, and Green from small-angle neutron scattering data for neon. These values of η, however, are clearly greater than those obtained by calculations using high-temperature expansions and renormalizationgroup techniques. On the other hand, if the effects of irrelevant variables are given by the estimate used in correcting the scattering data, the η value computed from the scattering curves agrees with the theoretical results

    How Phase-Breaking Affects Quantum Transport Through Chaotic Cavities

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    We investigate the effects of phase-breaking events on electronic transport through ballistic chaotic cavities. We simulate phase-breaking by a fictitious lead connecting the cavity to a phase-randomizing reservoir and introduce a statistical description for the total scattering matrix, including the additional lead. For strong phase-breaking, the average and variance of the conductance are calculated analytically. Combining these results with those in the absence of phase-breaking, we propose an interpolation formula, show that it is an excellent description of random-matrix numerical calculations, and obtain good agreement with several recent experiments.Comment: 4 pages, revtex, 3 figures: uuencoded tar-compressed postscrip

    Research Progress Reports: Fruit and Vegetable Processing and Technology Division, Department of Horticulture [1967]

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    Evaluation of snap bean varieties for processing / Wilbur A. Gould and William Hildebolt -- Evaluation of various grape cultivars for processing. I. Table wines ; Recommended fruit varieties for canning and freezing / J. F. Gallander -- Evaluation of tomato varieties for processing / W. A. Gould, J. R. Geisman, C. S. Parrott, J. H. McClelland and W. N. Brown -- The effect of different levels of sugar and acid on the quality of apple fruit juice blends / James Gallander and Harold Stammer -- Epidermal sloughing of snap beans as influenced by processing variables / William Hildebolt and W. A. Gould -- Effect of stannous chloride on the color of glass packed kraut / J. R. Geisman -- Proteins and enzymes in the apple fruit in relation to variety and maturation ; Proteins and enzymes in tomato fruits / Robert L. Clements -- Effect of food additives on quality of canned tomatoes / Wilbur A. Gould -- Effects of selective herbicides on the composition and quality of tomatoes / W. A. Gould, J. R. Geisman, E. K. Alban and John Deppen -- Trace levels of pesticide residues in agricultural commodities in marketing channels / W. A. Gould, J. R. Geisman, E. K. Alban, John Deppen, and P. van Pottlesberghe -- Removal of DDT residues by unit operations in preparing and processing spinach / J. R. Geisman, John Deppen and Benita Yao -- The use of chlorine dioxide in handling and holding mechanically harvested tomatoes / J. R. Geisman, Winston D. Bash, Edwin Schmidt, Jr., Linda Hamrick and W. A. Gould -- Effect of mechanical harvesting and handling of tomatoes on quality of canned tomatoes / Wilbur A. Gould, J. R. Geisman, Edwin Schmidt, Jr., John McClelland and W. N. Brow

    LSST Science Book, Version 2.0

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    A survey that can cover the sky in optical bands over wide fields to faint magnitudes with a fast cadence will enable many of the exciting science opportunities of the next decade. The Large Synoptic Survey Telescope (LSST) will have an effective aperture of 6.7 meters and an imaging camera with field of view of 9.6 deg^2, and will be devoted to a ten-year imaging survey over 20,000 deg^2 south of +15 deg. Each pointing will be imaged 2000 times with fifteen second exposures in six broad bands from 0.35 to 1.1 microns, to a total point-source depth of r~27.5. The LSST Science Book describes the basic parameters of the LSST hardware, software, and observing plans. The book discusses educational and outreach opportunities, then goes on to describe a broad range of science that LSST will revolutionize: mapping the inner and outer Solar System, stellar populations in the Milky Way and nearby galaxies, the structure of the Milky Way disk and halo and other objects in the Local Volume, transient and variable objects both at low and high redshift, and the properties of normal and active galaxies at low and high redshift. It then turns to far-field cosmological topics, exploring properties of supernovae to z~1, strong and weak lensing, the large-scale distribution of galaxies and baryon oscillations, and how these different probes may be combined to constrain cosmological models and the physics of dark energy.Comment: 596 pages. Also available at full resolution at http://www.lsst.org/lsst/sciboo

    Parent-of-origin-specific allelic associations among 106 genomic loci for age at menarche.

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    Age at menarche is a marker of timing of puberty in females. It varies widely between individuals, is a heritable trait and is associated with risks for obesity, type 2 diabetes, cardiovascular disease, breast cancer and all-cause mortality. Studies of rare human disorders of puberty and animal models point to a complex hypothalamic-pituitary-hormonal regulation, but the mechanisms that determine pubertal timing and underlie its links to disease risk remain unclear. Here, using genome-wide and custom-genotyping arrays in up to 182,416 women of European descent from 57 studies, we found robust evidence (P < 5 × 10(-8)) for 123 signals at 106 genomic loci associated with age at menarche. Many loci were associated with other pubertal traits in both sexes, and there was substantial overlap with genes implicated in body mass index and various diseases, including rare disorders of puberty. Menarche signals were enriched in imprinted regions, with three loci (DLK1-WDR25, MKRN3-MAGEL2 and KCNK9) demonstrating parent-of-origin-specific associations concordant with known parental expression patterns. Pathway analyses implicated nuclear hormone receptors, particularly retinoic acid and γ-aminobutyric acid-B2 receptor signalling, among novel mechanisms that regulate pubertal timing in humans. Our findings suggest a genetic architecture involving at least hundreds of common variants in the coordinated timing of the pubertal transition
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