67,709 research outputs found

    Ionization experiment

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    Mariner space probe ionization chamber and Geiger counter experiments on galactic radiation entering solar syste

    ERTS-1 investigation of wetlands ecology

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    The author has identified the following significant results. Data from aircraft can be used for large scale mapping where detailed information is necessary, whereas Landsat-1 data are useful for rapid mapping of gross wetland boundaries and vegetative composition and assessment of seasonal change plant community composition such as high and low growth forms of Spartina alterniflora, Juncus roemarianus, and Spartina cynosuroides. Spoil disposal and wetland ditching activities may also be defined. Wetland interpretation is affected by tidal stage; drainage patterns are more easily detected at periods of low water. Species discrimination is easier at periods of high water during the growing season; upper wetland boundaries in fresh water tidal marshes are more easily delineated during the winter months when marsh vegetation is largely dead or dormant. Fresh water discharges from coastal streams may be inferred from the species composition of contiguous wetlands

    Interpretation of wetlands ecology from ERTS

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    There are no author-identified significant results in this report

    Comparative utility of LANDSAT-1 and Skylab data for coastal wetland mapping and ecological studies

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    Skylab 190-A photography and LANDSAT-1 analog data have been analyzed to determine coastal wetland mapping potential as a near term substitute for aircraft data and as a long term monitoring tool. The level of detail and accuracy of each was compared. Skylab data provides more accurate classification of wetland types, better delineation of freshwater marshes and more detailed analysis of drainage patterns. LANDSAT-1 analog data is useful for general classification, boundary definition and monitoring of human impact in wetlands

    Vacuum polarization of scalar fields near Reissner-Nordstr\"{o}m black holes and the resonance behavior in field-mass dependence

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    We study vacuum polarization of quantized massive scalar fields ϕ\phi in equilibrium at black-hole temperature in Reissner-Nordstr\"{o}m background. By means of the Euclidean space Green's function we analytically derive the renormalized expression H_{H} at the event horizon with the area 4πr+24\pi r_{+}^{2}. It is confirmed that the polarization amplitude H_{H} is free from any divergence due to the infinite red-shift effect. Our main purpose is to clarify the dependence of H_{H} on field mass mm in relation to the excitation mechanism. It is shown for small-mass fields with mr+1mr_{+}\ll1 how the excitation of H_{H} caused by finite black-hole temperature is suppressed as mm increases, and it is verified for very massive fields with mr+1mr_{+}\gg1 that H_{H} decreases in proportion to m2m^{-2} with the amplitude equal to the DeWitt-Schwinger approximation. In particular, we find a resonance behavior with a peak amplitude at mr+0.38mr_{+}\simeq 0.38 in the field-mass dependence of vacuum polarization around nearly extreme (low-temperature) black holes. The difference between Scwarzschild and nearly extreme black holes is discussed in terms of the mass spectrum of quantum fields dominant near the event horizon.Comment: 24 pages, 1 figure Accepted in PR

    Skylab-EREP investigations of wetlands ecology

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    There are no author-identified significant results in this report

    Skylab - EREP investigations of wetlands ecology

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    There are no author-identified significant results in this report

    High-temperature bearing lubricants

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    Synthetic paraffinic oil lubricates ball bearings at temperatures in the 600 degrees F range. The lubricant contains antiwear and antifoam additives, is thermally stable in the high temperature range, but requires protection from oxygen

    The B-L/Electroweak Hierarchy in Smooth Heterotic Compactifications

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    E8 X E8 heterotic string and M-theory, when appropriately compactified, can give rise to realistic, N=1 supersymmetric particle physics. In particular, the exact matter spectrum of the MSSM, including three right-handed neutrino supermultiplets, one per family, and one pair of Higgs-Higgs conjugate superfields is obtained by compactifying on Calabi-Yau manifolds admitting specific SU(4) vector bundles. These "heterotic standard models" have the SU(3)_{C} X SU(2)_{L} X U(1)_{Y} gauge group of the standard model augmented by an additional gauged U(1)_{B-L}. Their minimal content requires that the B-L gauge symmetry be spontaneously broken by a vacuum expectation value of at least one right-handed sneutrino. In a previous paper, we presented the results of a renormalization group analysis showing that B-L gauge symmetry is indeed radiatively broken with a B-L/electroweak hierarchy of O(10) to O(10^{2}). In this paper, we present the details of that analysis, extending the results to include higher order terms in tan[beta]^{-1} and the explicit spectrum of all squarks and sleptons.Comment: 60 pages, 6 figure

    Heterotic Line Bundle Standard Models

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    In a previous publication, arXiv:1106.4804, we have found 200 models from heterotic Calabi-Yau compactifications with line bundles, which lead to standard models after taking appropriate quotients by a discrete symmetry and introducing Wilson lines. In this paper, we construct the resulting standard models explicitly, compute their spectrum including Higgs multiplets, and analyze some of their basic properties. After removing redundancies we find about 400 downstairs models, each with the precise matter spectrum of the supersymmetric standard model, with one, two or three pairs of Higgs doublets and no exotics of any kind. In addition to the standard model gauge group, up to four Green-Schwarz anomalous U(1) symmetries are present in these models, which constrain the allowed operators in the four-dimensional effective supergravity. The vector bosons associated to these anomalous U(1) symmetries are massive. We explicitly compute the spectrum of allowed operators for each model and present the results, together with the defining data of the models, in a database of standard models accessible at http://www-thphys.physics.ox.ac.uk/projects/CalabiYau/linebundlemodels/index.html. Based on these results we analyze elementary phenomenological properties. For example, for about 200 models all dimension four and five proton decay violating operators are forbidden by the additional U(1) symmetries.Comment: 55 pages, Latex, 3 pdf figure
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