37,280 research outputs found

    O\u27er the Far Blue Mountain

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    O\u27er the far blue mountain,O\u27er the white sea foam,Come thou long parted one,Back to thy home.When the bright fire shineth,Sad looks thy place;While the true heart pineth,Missing thy face.O\u27er the far blue mountain,O\u27er the white sea foam,Come thou long parted one,Come to thy home.Ah!Ah!Music is sorrowfulSince thou art gone,Sisters are mourning thee,Come to thine own.Hark! how lone voices callBack to thy rest,Come to thy Fathers hall,Thy Mothers breast.O\u27er the far blue mountain,O\u27er the white sea foam,Come thou long parted one,Come to thy home.Ah!Ah

    The Phase-Space Density Profiles of Cold Dark Matter Halos

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    We examine the coarse-grained phase-space density profiles of a set of recent, high-resolution simulations of galaxy-sized Cold Dark Matter (CDM) halos. Over two and a half decades in radius the phase-space density closely follows a power-law, ρ/σ3∝r−α\rho/\sigma^3 \propto r^{-\alpha}, with α=1.875\alpha = 1.875. This behaviour matches the self-similar solution obtained by Bertschinger for secondary infall in a uniformly expanding universe. On the other hand, the density profile corresponding to Bertschinger's solution (a power-law of slope r2α−6r^{2\alpha-6}) differs significantly from the density profiles of CDM halos. We show that isotropic mass distributions with power-law phase-space density profiles form a one-parameter family of structures controlled by Îș\kappa, the ratio of the velocity dispersion to the peak circular velocity. For Îș=α=1.875\kappa=\alpha=1.875 one recovers the power-law solution ρ∝r2α−6\rho \propto r^{2\alpha-6}. For Îș\kappa larger than some critical value, Îșcr\kappa_{cr}, solutions become non-physical, leading to negative densities near the center. The critical solution, Îș=Îșcr\kappa =\kappa_{cr}, has the narrowest phase-space density distribution compatible with the power-law phase-space density stratification constraint. Over three decades in radius the critical solution is indistinguishable from an NFW profile. Our results thus suggest that the NFW profile is the result of a hierarchical assembly process that preserves the phase-space stratification of Bertschinger's infall model but which ``mixes'' the system maximally, perhaps as a result of repeated merging.Comment: 16 pages, 4 figures; submitted to The Astrophysical Journa

    Anomalous low temperature specific heat of He-3 inside nanotube bundles

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    Helium atoms and hydrogen molecules can be strongly bound inside interstitial channels within bundles of carbon nanotubes. An exploration of the low energy and low temperature properties of He-3 atoms is presented here. Recent study of the analogous He-4 system has shown that the effect of heterogeneity is to yield a density of states N(E) that is qualitatively different from the one-dimensional (1D) form of N(E) that would occur for an ideal set of identical channels. In particular, the functional form of N(E) is that of a 4D gas near the very lowest energies and a 2D gas at somewhat higher energies. Similar behavior is found here for He-3. The resulting thermodynamic behavior of this fermi system is computed, yielding an anomalous form of the heat capacity and its dependence on coverage.Comment: 11 pages, 6 figure

    The genomics of neonatal abstinence syndrome

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    Significant variability has been observed in the development and severity of neonatal abstinence syndrome (NAS) among neonates exposed to prenatal opioids. Since maternal opioid dose does not appear to correlate directly with neonatal outcome, maternal, placental, and fetal genomic variants may play important roles in NAS. Previous studies in small cohorts have demonstrated associations of variants in maternal and infant genes that encode the Ό-opioid receptor (OPRM1), catechol-O-methyltransferase (COMT), and prepronociceptin (PNOC) with a shorter length of hospital stay and less need for treatment in neonates exposed to opioids in utero. Consistently falling genomic sequencing costs and computational approaches to predict variant function will permit unbiased discovery of genomic variants and gene pathways associated with differences in maternal and fetal opioid pharmacokinetics and pharmacodynamics and with placental opioid transport and metabolism. Discovery of pathogenic variants should permit better delineation of the risk of developing more severe forms of NAS. This review provides a summary of the current role of genomic factors in the development of NAS and suggests strategies for further genomic discovery

    ECONOMIC FEASIBILITY OF BIODIESEL PRODUCTION IN NORTH DAKOTA

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    The U. S. biodiesel industry is rapidly expanding due to energy production concerns, environmental concerns, and recent legislation. The most common type of biodiesel in the United States is derived from soybean oil. Soybeans are a major crop in North Dakota and could easily supply a 5 million gallon per year biodiesel facility. Potential market segments of a biodiesel facility in North Dakota include agriculture, construction, and state fleet sectors based on current diesel use. However, with existing technology and no subsidy, biodiesel operation and investment costs for a North Dakota facility are not competitive with petroleum diesel. Using soybean oil prices of 17 cents to 25 cents per pound, the per gallon cost of producing diesel in southeastern North Dakota ranges between 2.02and2.02 and 2.64, while the wholesale price for regular diesel is $0.91. The cost of producing biodiesel is highly dependent on the price and availability of soybean oil. While biodiesel production technology is feasible and fairly simple, producing biodiesel in North Dakota is not economically feasible at least in the foreseeable future.biodiesel, soybeans, economic feasibility, Resource /Energy Economics and Policy,

    ECONOMIC FEASIBILITY OF BIODIESEL PRODUCTION IN NORTH DAKOTA

    Get PDF
    The U. S. biodiesel industry is rapidly expanding due to energy production concerns, environmental concerns, and recent legislation. The most common type of biodiesel in the United States is derived from soybean oil. Soybeans are a major crop in North Dakota and could easily supply a 5 million gallon per year biodiesel facility. Potential market segments of a biodiesel facility in North Dakota include agriculture, construction, and state fleet sectors based on current diesel use. However, with existing technology and no subsidy, biodiesel operation and investment costs for a North Dakota facility are not competitive with petroleum diesel. Using soybean oil prices of 17 cents to 25 cents per pound, the per gallon cost of producing diesel in southeastern North Dakota ranges between 2.02and2.02 and 2.64, while the wholesale price for regular diesel is $0.91. The cost of producing biodiesel is highly dependent on the price and availability of soybean oil. While biodiesel production technology is feasible and fairly simple, producing biodiesel in North Dakota is not economically feasible at least in the foreseeable future.biodiesel, soybeans, economic feasibility, Resource /Energy Economics and Policy,
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