4,695 research outputs found

    Gamma ray lines from TeV dark matter

    Full text link
    We calculate, using unitarity, a lower bound on the branching ratio χχ→γγ\chi\chi\to \gamma\gamma and χχ→γZ\chi\chi\to \gamma Z, where χ\chi is any halo dark matter particle that has W+W−W^+W^- as one of the major annihilation modes. Examples of such particles are supersymmetric particles with a dominant Higgsino component, or heavy triplet neutrinos. A substantial branching ratio is found for the γγ\gamma\gamma and γZ\gamma Z modes. We estimate the strength of the monoenergetic γ\gamma ray lines that result from such annihilations in the Galactic or LMC halos. (Latex file; 2 compressed uuencoded postscript figures available by anonymous ftp from vanosf.physto.se in file pub/figures/lines.uu)Comment: 11 pages, USITP-94-03; PAR-LPTHE 94-0

    Production of butanol by fermentation in the presence of cocultures of clostridium

    Get PDF
    Sugars are converted to a mixture of solvents including butanol by a fermentation process employing a coculture of microorganisms of the Clostridium genus, one of said microorganisms favoring the production of butyric acid and the other of which converts the butyric acid so produced to butanol. The use of a coculture substantially increases the yield of butanol over that obtained using a culture employing only one microorganism

    Development of an infrared radiative heating model

    Get PDF
    Infrared radiative transfer solution algorithms used in global circulation models were assessed. Computation techniques applicable to the Ames circulation model are identified. Transmission properties of gaseous CO2, H2O, and O3 are gathered, and a computer program is developed, using the line parameter tape and Voight profile subroutine, which computes the transmission of CO2, H2O, and O3. A computer code designed to compute atmospheric cooling rates was developed

    Clumpy Neutralino Dark Matter

    Get PDF
    We investigate the possibility to detect neutralino dark matter in a scenario in which the galactic dark halo is clumpy. We find that under customary assumptions on various astrophysical parameters, the antiproton and continuum gamma-ray signals from neutralino annihilation in the halo put the strongest limits on the clumpiness of a neutralino halo. We argue that indirect detection through neutrinos from the Earth and the Sun should not be much affected by clumpiness. We identify situations in parameter space where the gamma-ray line, positron and diffuse neutrino signals from annihilations in the halo may provide interesting signals in upcoming detectors.Comment: 19 pages, 10 eps-figures (included), LaTeX, uses RevTe

    Demographics and the Political Sustainability of Pay-as-you-go Social Security

    Get PDF
    The net present value of costs and benefits from a pay-as-you-go social security system are negative for young people and positive for the elderly. If people all vote their financial self-interest, there will be a pivotal age such that those who are younger favor smaller social security benefits and those who are older will favor larger benefits. For persons of each age and sex, we estimate the expected present value gained or lost from a small permanent increase in the amount of benefits, where the cost of these benefits is divided equally among the population of working age. Assuming that everyone votes his or her long run financial self-interest, and calculating the number of voters in the population of each age and sex, we can determine whether there is majority support for an increase or a decrease in social security benefits. We use statistics on the age distribution and mortality rates for the United States to explore the sensitivity of political support for social security to alternative assumptions about the discount rate, excess burden in taxation, voter participation rates, and birth, death, and migration rates. We find that a once-and-for-all decrease in benefits would be defeated by a majority of selfish voters under a wide range of parameters. We also study the predicted majority outcomes of votes on changing the retirement age.
    • …
    corecore