Now showing items 1-20 of 224

    • Climatic And Biogeochemical Effects Of A Galactic Gamma-Ray Burst 

      Melott, Adrian L., Thomas, Brian C., Hogan, Daniel P., Ejzak, Larissa M., and Jackman, Charles H.,
      It is likely that one or more gamma-ray bursts within our galaxy have strongly irradiated the Earth in the last Gy. This produces significant atmospheric ionization and dissociation, resulting in ozone depletion and ...
    • Atmospheric Consequences of Cosmic Ray Variability in the Extragalactic Shock Model 

      Murray, Michael J., Melott, Adrian L., Krejci, Alex J., Medvedev, Mikhail V., Wilson, Graham W., and Murray, Michael J.
      It has been suggested that galactic shock asymmetry induced by our galaxy's infall toward the Virgo Cluster may be a source of periodicity in cosmic ray exposure as the solar system oscillates normal to the galactic plane, ...
    • Ozone Abundance In A Nitrogen-Carbon Dioxide Dominated Terrestrial Paleoatmosphere 

      Thomas, Brian C., Melott, Adrian L., Martin, Larry D., and Jackman, Charles H.
      We compute the ozone distribution for a model terrestrial paleoatmosphere in which the present oxygen abundance is largely replaced by carbon dioxide, which we argue is a reasonable working assumption. In principle, the ...
    • Modeling Atmospheric Effects Of The September 1859 Solar Flare 

      Thomas, Brian C., Jackman, Charles H., and Melott, Adrian L.
      We have modeled atmospheric effects, especially ozone depletion, due to a solar proton event which probably accompanied the extreme magnetic storm of 1-2 September 1859. We use an inferred proton fluence for this event as ...
    • Quantifying The Bull's Eye Effect 

      Thomas, Brian C., Melott, Adrian L., Feldman, Hume A., and Shandarin, Sergei F.
      We have used N-body simulations to develop two independent methods to quantify redshift distortions known as the Bull's Eye effect (large scale infall plus small scale virial motion). This effect depends upon the mass ...
    • Superluminous Supernovae No Threat From Eta Carinae 

      Thomas, Brian C., Melott, Adrian L., Fields, Brian D., and Anthony-Twarog, Barbara J.
      Recently Supernova 2006gy was noted as the most luminous ever recorded, with a total radiated energy of -10(44) Joules. It was proposed that the progenitor may have been a massive evolved star similar to n Carinae, which ...
    • Terrestrial Consequences Of Spectral And Temporal Variability In Ionizing Photon Events 

      Thomas, Brian C., Ejzak, Larissa M., Melott, Adrian L., and Medvedev, Mikhail V.
      Gamma-Ray Bursts (GRBs) directed at Earth from within a few kpc may have damaged the biosphere, primarily through changes in atmospheric chemistry which admit greatly increased Solar UV. However, GRBs are highly variable ...
    • Terrestrial Ozone Depletion Due To A Milky Way Gamma-Ray Burst 

      Thomas, Brian C., Jackman, Charles H., Melott, Adrian L., Laird, Claude M., Stolarski, Richard S., Gehrels, Neil, Cannizzo, John K., and Hogan, Daniel P.
      Based on cosmological rates, it is probable that at least once in the last Gy the Earth has been irradiated by a gamma-ray burst in our Galaxy from within 2 kpc. Using a two-dimensional atmospheric model we have performed ...
    • A Lookup Table To Compute High Energy Cosmic Ray Effects on Terrestrial Atmospheric Chemistry 

      Thomas, Brian C., Melott, Adrian L., Atri, Dimitra, and Krejci, Alex J.
      A variety of events such as gamma-ray and supernovae may expose the Earth to an increased flux of high-energy cosmic rays, with potentially important effects on the biosphere. Existing atmospheric chemistry software does ...
    • Did A Gamma-Ray Burst Initiate The Late Ordovician Mass Extinction 

      Melott, Adrian L., Lieberman, B. S., Laird, Claude M., Medvedev, Mikhail V., Thomas, Brian C., Cannizzo, John K., Gehrels, Neil, and Jackman, Charles H.
      Gamma-ray bursts (GRBs) produce a flux of radiation detectable across the observable Universe. A GRB within our own galaxy could do considerable damage to the Earth's biosphere; rate estimates suggest that a dangerously ...
    • Does Nitrate Deposition Following Astrophysical Ionizing Radiation Events 

      Thomas, Brian C. and Honeyman, Michelle D.
      As diversity in amphibian species declines, the search for causes has intensified. Work in this area has shown that amphibians are especially susceptible to the combination of heightened UVB radiation and increased nitrate ...
    • Gamma-Ray Bursts And The Earth Exploration Of Atmospheric Biological Climatic And Biogeochemical Effects 

      Thomas, Brian C., Melott, Adrian L., Jackman, Charles H., Laird, Claude M., Medvedev, Mikhail V., Stolarski, Richard S., Gehrels, Neil, Cannizzo, John K., Hogan, Daniel P., and Ejzak, Larissa M.
      Gamma-Ray Bursts (GRBs) are likely to have made a number of significant impacts on the Earth during the last billion years. The gamma radiation from a burst within a few kpc would quickly deplete much of the Earth's ...
    • Gamma-ray Bursts and Terrestrial Planetary Atmospheres 

      Thomas, Brian C. and Melott, Adrian L.
      We describe results of modelling the effects on Earth-like planets of long-duration gamma-ray bursts (GRBs) within a few kiloparsecs. A primary effect is generation of nitrogen oxide compounds which deplete ozone. Ozone ...
    • Gamma-Ray Bursts As A Threat To Life On Earth 

      Thomas, Brian C.
      Gamma-ray bursts (GRBs) are likely to have made a number of significant impacts on the Earth during the last billion years. The gamma radiation from a burst within a few kiloparsecs would quickly deplete much of the Earth's ...
    • Late Ordovician Geographic Patterns of Extinction 

      Thomas, Brian C. and Melott, Adrian L.
      Based on the intensity and rates of various kinds of intense ionizing radiation events such as supernovae and gamma-ray bursts, it is likely that the Earth has been subjected to one or more events of potential mass extinction ...
    • In-Class Discussion Activity On The Nature of Science and Intelligent Design 

      Thomas, Brian C.
      In this paper I describe an in-class discussion activity aimed at helping elementary education majors in a physical science course think about issues surrounding the inclusion of "Intelligent Design" in public school science ...
    • Wind Power: It's The Right Thing to Do 

      Siehndel, Ray D.; Miller, Chris
      This paper examines a number of considerations, problems, solutions and costs associated with wind power. The legal, social and environmental positives outweigh the negatives that result in the conclusion of "why would ...
    • Revisiting Entity Choice for Small Business Owners 

      Clevenger, Novella; Hyatt, Venita R.
      Recent changes and proposed changes in federal tax laws may affect the important decision about which entity to choose when starting a small business. Reduction in the rate of tax on dividends to 15 percent has lessened ...
    • Corporate Inversion: A Symbol of a Changing Paradigm of Corporate Behavior? Balancing Global Competitiveness, Fiduciary Duty, and Ethical Behavior 

      Clevenger, Novella; Crumpacker, Martha; Siehndel, Ray D.
      Global competitiveness is affecting U.S. companies in a variety of ways. one is tax policy. U.S. federal tax policy in a global environment causes many U.S.-based companies to operate at a disadvantage to some foreign ...
    • Examining the Mediating Relationship of "Play" on Ritual Enduring Involvement 

      McGinnis, Lee; Gentry, James W.
      The focus of this study is the examination of the effects of perceived sacredness of a particular consumer ritual on consumers' level of "play" and enduring involvement. In this study, the sociological concept ...