9,455 research outputs found

    Modeling Solar Lyman Alpha Irradiance

    Get PDF
    Solar Lyman alpha irradiance is estimated from various solar indices using linear regression analyses. Models developed with multiple linear regression analysis, including daily values and 81-day running means of solar indices, predict reasonably well both the short- and long-term variations observed in Lyman alpha. It is shown that the full disk equivalent width of the He line at 1083 nm offers the best proxy for Lyman alpha, and that the total irradiance corrected for sunspot effect also has a high correlation with Lyman alpha

    Fermi gas in harmonic oscillator potentials

    Full text link
    Assuming the validity of grand canonical statistics, we study the properties of a spin-polarized Fermi gas in harmonic traps. Universal forms of Fermi temperature TFT_F, internal energy UU and the specific heat per particle of the trapped Fermi gas are calculated as a {\it function} of particle number, and the results compared with those of infinite number particles.Comment: 8 pages, 1 figure, LATE

    Vitamin K catabolite inhibition of ovariectomy-induced bone loss: Structure–activity relationship considerations

    Get PDF
    The potential benefit of vitamin K as a therapeutic in osteoporosis is controversial and the vitamin K regimen being used clinically (45 mg/day) employs doses that are many times higher than required to ensure maximal gamma‐carboxylation of the vitamin K‐dependent bone proteins. We therefore tested the hypothesis that vitamin K catabolites, 5‐carbon (CAN5C) and 7‐carbon carboxylic acid (CAN7C) aliphatic side‐chain derivatives of the naphthoquinone moiety exert an osteotrophic role consistent with the treatment of osteoporosis

    Determining the Quark Mixing Matrix From CP-Violating Asymmetries

    Full text link
    If the Standard Model explanation of CP violation is correct, then measurements of CP-violating asymmetries in BB meson decays can in principle determine the entire quark mixing matrix.Comment: 8 pages (plain TeX), 1 figure (postscript file appended), DAPNIA/SPP 94-06, NSF-PT-94-2, UdeM-LPN-TH-94-18

    Exploring CP Violation with B_d -> D K_s Decays

    Full text link
    We (re)examine CP violation in the decays B_d -> D K_s, where D represents D^0, D(bar), or one of their excited states. The quantity sin2(2β+γ)\sin^2(2\beta + \gamma) can be extracted from the time-dependent rates for Bd(t)>Dˉ0KsB_d(t) -> {\bar D}^{**0} K_s and Bd(t)>D0KsB_d(t) -> D^{**0} K_s, where the D0D^{**0} decays to D()+πD^{(*)+}\pi^-. If one considers a non-CP-eigenstate hadronic final state to which both D(bar) and D^0 can decay (e.g. K+πK^+\pi^-), then one can obtain two of the angles of the unitarity triangle from measurements of the time-dependent rates for Bd(t)>(K+π)DKsB_d(t) -> (K^+\pi^-)_{D K_s} and Bd(t)>(Kπ+)DKsB_d(t) -> (K^-\pi^+)_{D K_s}. There are no penguin contributions to these decays, so all measurements are theoretically clean.Comment: 15 pages, LaTeX, no figure

    Adolescents care but don't feel responsible for farm animal welfare

    Get PDF
    Adolescents are the next generation of consumers with the potential to raise standards of farm animal welfare—to theirsatisfaction—if their preferences and concerns are translated into accurate market drivers and signals. There are no published data about adolescent views of farm animal welfare to allow meaningful design, implementation, and evaluation of educational strategies to improve consideration of—and behavior toward—farm animals. Knowledge of farm animal welfare, as well as beliefs and attitudes about farm animal welfare and behavioral intention relevant to it were determined in a sample of ukadolescents, using a survey incorporating an extended version of the theory of planned behavior and novel assessment tools. Our results indicate that adolescents have only a limited knowledge of welfare problems for farm animals and welfare-relevant product labels. Intentions to identify welfare standards for the animals from whom their food was derived were weak. Although they cared about farm animal welfare and agreed with fundamental principles—for example, the provision of space and the absence of pain and suffering—like adults they held limited belief in the power and responsibility that they possess through their choices as consumers; responsibility was often shifted to others, such as the government and farmers

    ANOMALOUS GAUGE BOSON INTERACTIONS

    Get PDF
    We discuss the direct measurement of the trilinear vector boson couplings in present and future collider experiments. The major goals of such experiments will be the confirmation of the Standard Model (SM) predictions and the search for signals of new physics. We review our current theoretical understanding of anomalous trilinear gauge boson self-interactions. If the energy scale of the new physics is 1\sim 1 TeV, these low energy anomalous couplings are expected to be no larger than O(102){\cal O}(10^{-2}). Constraints from high precision measurements at LEP and low energy charged and neutral current processes are critically reviewed.Comment: 53 pages with 17 embedded figures, LaTeX, uses axodraw.sty, figures available on request. The complete paper, is available at ftp://phenom.physics.wisc.edu/pub/preprints/1995/madph-95-871.ps.Z or http://phenom.physics.wisc.edu/pub/preprints/1995/madph-95-871.ps.Z Summary of the DPF Working Subgroup on Anomalous Gauge Boson Interactions of the DPF Long Range Planning Stud

    Fluid Mechanical and Electrical Fluctuation Forces in Colloids

    Full text link
    Fluctuations in fluid velocity and fluctuations in electric fields may both give rise to forces acting on small particles in colloidal suspensions. Such forces in part determine the thermodynamic stability of the colloid. At the classical statistical thermodynamic level, the fluid velocity and electric field contributions to the forces are comparable in magnitude. When quantum fluctuation effects are taken into account, the electric fluctuation induced van der Waals forces dominate those induced by purely fluid mechanical motions. The physical principles are applied in detail for the case of colloidal particle attraction to the walls of the suspension container and more briefly for the case of forces between colloidal particles.Comment: ReVTeX format, one *.eps figur

    Physisorption of Nucleobases on Graphene

    Get PDF
    We report the results of our first-principles investigation on the interaction of the nucleobases adenine (A), cytosine (C), guanine (G), thymine (T), and uracil (U) with graphene, carried out within the density functional theory framework, with additional calculations utilizing Hartree--Fock plus second-order Moeller-Plesset perturbation theory. The calculated binding energy of the nucleobases shows the following hierarchy: G > T ~ C ~ A > U, with the equilibrium configuration being very similar for all five of them. Our results clearly demonstrate that the nucleobases exhibit significantly different interaction strengths when physisorbed on graphene. The stabilizing factor in the interaction between the base molecule and graphene sheet is dominated by the molecular polarizability that allows a weakly attractive dispersion force to be induced between them. The present study represents a significant step towards a first-principles understanding of how the base sequence of DNA can affect its interaction with carbon nanotubes, as observed experimentally.Comment: 7 pages, 3 figure

    Direct measurement of quantum phase gradients in superfluid 4He flow

    Full text link
    We report a new kind of experiment in which we generate a known superfluid velocity in a straight tube and directly determine the phase difference across the tube's ends using a superfluid matter wave interferometer. By so doing, we quantitatively verify the relation between the superfluid velocity and the phase gradient of the condensate macroscopic wave function. Within the systematic error of the measurement (~10%) we find v_s=(hbar/m_4)*(grad phi)
    corecore