12,576 research outputs found

    Dark Matter Constraints in Heterotic M-Theory with Five-Brane Dominance

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    The phenomenological implications of the M-theory limit in which supersymmetry is broken by the auxiliary fields of five-brane moduli is investigated. Assuming that the lightest neutralino provides the dark matter in the universe, constraints on the sparticle spectrum are obtained. Direct detection rates for dark matter are estimated.Comment: 10 pages, LaTeX file plus 8 EPS figure

    Net energy analysis of solar and conventional domestic hot water systems in Melbourne, Australia

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    It is commonly assumed that solar hot water systems save energy and reduce greenhouse gas emissions. Very rarely has the life-cycle energy requirements of solar hot water systems been analysed, including their embodied energy. The extent to which solar hot water systems save energy compared to conventional systems in Melbourne, Australia, is shown through a comparative net energy analysis. The solar systems provided a net energy saving compared to the conventional systems after 0.5 to 2 years, for electricity and gas systems respectively.<br /

    Orientation and solvatochromism of dyes in liquid crystals.

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    The orientation and solvatochromism of some dye molecules in a liquid crystal have been investigated. Interactions with the host and the structure of the dye molecule affect the macroscopic alignment of dichroic dye molecules in a liquid crystal: It was observed that some dye molecules show a large bathochromic shift of their absorption maxima in the liquid crystal host relative to the situation in isotropic solvents. It is suggested that this is due to the occurrence of a much weaker reaction field in the anisotropic, rigid host. These dye molecules show little or no apparent order in the anisotropic host despite the observation of a reduction in the electro optic switching time when the dye is present. The highest degree of macroscopic alignment was observed for a merocyanine compound, which showed the smallest solvatochromic shift in the liquid crystal host. These results are discussed in terms of the steric, dipolar and hydrogen bond interactions between the guest and the host

    Reconnaissance Study of Pleistocene Lake and Fluvial Deposits In and Near Ancestral Yellowstone Lake, Wyoming

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    Seven sequences of Pleistocene strata, five of them predominantly lacustrine, are described from outcrops north of Yellowstone Lake. These are (1) Turbid Lake sequence, 30–50 feet of white pumiceous claystone and tuff with carbonaceous partings and a distinctive compositional pattern of excesses and deficiencies of many elements; (2) Yellowstone Falls sequence, 75 feet or more of varved white claystone and tuff containing pollen and diatoms, overlain by gray conglomerate and sandstone; (3) Hayden Valley sequence, 200 feet or more of gray and white silt and claystone containing sparse diatoms; (4) Alum Creek sequence, 30 feet or more of bedded sand and gravel with lesser amounts of clay; (5) Mudkettle sequence, 150 feet or more of light gray to white, soft clay and claystone with lesser amounts of sandstone and conglomerate, moderately lithified in part, and containing some pollen and diatoms; (6) Astringent Creek Sand (newly named), a gray, commonly unlithified sand as much as 300 feet thick and containing abundant volcanic debris; and (7) Pelican Valley sequence, 120 feet or more of light gray to white, soft clay, silt, sand, and some pumice pebble conglomerate and shard beds; finer grained beds contain diatoms, pollen, and carbonaceous debris that has a radiocarbon date of 7,550 ±350 years. Other localized deposits with radiocarbon dates and abundant diatoms consist of white carbonaceous tuffaceous clay and sand with an age of 9,440±300 years, in Gibbon Canyon, and a gray and white carbonaceous clay, silt, and sand with an age of 3,750+300 years at Bannock Ford in Yellowstone Canyon. Slight arching of the Upper Basin Member of the Plateau Rhyolite caused the Yellowstone River to develop an antecedent course across it. Uplift of the Pelican Valley area during the last 7,500 years averaged about one foot in 50 years

    Reconnaissance Study of Pleistocene Lake and Fluvial Deposits In and Near Ancestral Yellowstone Lake, Wyoming

    Get PDF
    Seven sequences of Pleistocene strata, five of them predominantly lacustrine, are described from outcrops north of Yellowstone Lake. These are (1) Turbid Lake sequence, 30–50 feet of white pumiceous claystone and tuff with carbonaceous partings and a distinctive compositional pattern of excesses and deficiencies of many elements; (2) Yellowstone Falls sequence, 75 feet or more of varved white claystone and tuff containing pollen and diatoms, overlain by gray conglomerate and sandstone; (3) Hayden Valley sequence, 200 feet or more of gray and white silt and claystone containing sparse diatoms; (4) Alum Creek sequence, 30 feet or more of bedded sand and gravel with lesser amounts of clay; (5) Mudkettle sequence, 150 feet or more of light gray to white, soft clay and claystone with lesser amounts of sandstone and conglomerate, moderately lithified in part, and containing some pollen and diatoms; (6) Astringent Creek Sand (newly named), a gray, commonly unlithified sand as much as 300 feet thick and containing abundant volcanic debris; and (7) Pelican Valley sequence, 120 feet or more of light gray to white, soft clay, silt, sand, and some pumice pebble conglomerate and shard beds; finer grained beds contain diatoms, pollen, and carbonaceous debris that has a radiocarbon date of 7,550 ±350 years. Other localized deposits with radiocarbon dates and abundant diatoms consist of white carbonaceous tuffaceous clay and sand with an age of 9,440±300 years, in Gibbon Canyon, and a gray and white carbonaceous clay, silt, and sand with an age of 3,750+300 years at Bannock Ford in Yellowstone Canyon. Slight arching of the Upper Basin Member of the Plateau Rhyolite caused the Yellowstone River to develop an antecedent course across it. Uplift of the Pelican Valley area during the last 7,500 years averaged about one foot in 50 years

    A new microscopic nucleon-nucleon interaction derived from relativistic mean field theory

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    A new microscopic nucleon-nucleon (NN) interaction has been derived for the first time from the popular relativistic mean field theory (RMFT) Lagrangian. The NN interaction so obtained remarkably relate to the inbuilt fundamental parameters of RMFT. Furthermore, by folding it with the RMFT-densities of cluster and daughter nuclei to obtain the optical potential, it's application is also examined to study the exotic cluster radioactive decays, and results obtained found comparable with the successfully used M3Y phenomenological effective NN interactions. The presently derived NN-interaction can also be used to calculate a number of other nuclear observables.Comment: 4 Pages 2 Figure

    Densities of 5-15 micron interplanetary dust particles

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    We have measured the densities of about 100 5-15 micron stratospheric IDPs. Great care was taken to minimize selection bias in the sample population. Masses were determined using an absolute x-ray analysis technique with a transmission electron microscope, and volumes were found using scanning electron microscope imagery. Unmelted chondritic particles have densities between 0.5 and 6.0 g/cc. Roughly half of the particles have densities below 2 g/cc, indicating appreciable porosity, but porosities greater than about 70 percent are rare. IDPs with densities above 3.5 g/cc usually contain large sulfide grains. We find no evidence of bimodality in the unmelted particle density distribution. Chondritic spherules (melted particles) have densities near 3.5 g/cc, consistent with previous results for deep sea spherules
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