4,695 research outputs found
Gamma ray lines from TeV dark matter
We calculate, using unitarity, a lower bound on the branching ratio
and , where is any halo
dark matter particle that has 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 and modes. We estimate the strength
of the monoenergetic 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
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
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
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
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.
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