Population Processes with Immigration

The paper contains the complete analysis of the Galton-Watson models with immigration, including the processes in the random environment, stationary or non-stationary ones. We also study the branching random walk on $Z^d$ with immigration and prove the existence of the limits for the first two correlation functions

Can Supersymmetry Naturally Explain the Positron Excess?

It has often been suggested that the cosmic positron excess observed by the HEAT experiment could be the consequence of supersymmetric dark matter annihilating in the galactic halo. Although it is well known that evenly distributed dark matter cannot account for the observed excess, if substantial amounts of local dark matter substructure are present, the positron flux would be enhanced, perhaps to the observed magnitude. In this paper, we attempt to identify the nature of the substructure required to match the HEAT data, including the location, size and density of any local dark matter clump(s). Additionally, we attempt to assess the probability of such substructure being present. We find that if the current density of neutralino dark matter is the result of thermal production, very unlikely ($\sim 10^{-4}$ or less) conditions must be present in local substructure to account for the observed excess.Comment: Version accepted by Physical Review

Spectrum, Winter 1992

Spectrum was a newsletter for students, faculty, staff and alumni of the Henry M. Goldman School of Dental Medicine, published from 1983-1992

Tidal Destruction of The First Dark Microhalos

We point out that the usual self-similarity in cold dark matter models is broken by encounters with individual normal galactic stars on sub-pc scale. Tidal heating and stripping must have redefined the density and velocity structures of the population of the Earth-mass dark matter halos, which are likely to have been the first bound structures to form in the Universe. The disruption rate depends strongly on {\it galaxy types} and the orbital distribution of the microhalos; in the Milky Way, stochastic radial orbits are destroyed first by stars in the triaxial bulge, microhalos on non-planar retrograde orbits with large pericenters and/or apocenters survive the longest. The final microhalo distribution in the {\it solar neighborhood} is better described as a superposition of filamentry microstreams rather than as a set of discrete spherical clumps in an otherwise homogeneous medium. We discuss its important consequences to our detections of microhalos by direct recoil signal and indirect annihilation signal.Comment: 13 pages, 3 figures, Astrophysical Journal, accepte

Benchmarking Utility Clean Energy Deployment: 2014

This report assembles data from more than 10 sources, including state Renewable Portfolio Standard (RPS) annual reports, U.S. Securities and Exchange Commission 10-K filings and Public Utility Commission reports, to show how 32 of the largest U.S. investor-owned electric utility holding companies stack up on renewable energy and energy efficiency

Staying on Course: Three Year Results of the National Guard Youth ChalleNGe Evaluation

Evaluates the effectiveness of a quasi-military residential and mentoring program that aims to place high school dropouts in employment, education, or military service and improve outcomes including indicators of health, lifestyle, and delinquency

Effect of Aquathol K on Hydrilla verticillata (L.F.) Royle

A recently synthesized herbicide Aquathol K was tested on the water weed Hydrilla verticil. Results from the laboraoty tests indicated that Aquathol K with concentrations ranging from 1.0 mg/l to 2.0 mg/l can kill this weed. EVidently, 100% injury was achieved within 10 days for the plants treated with the highest concentration., 2. 0 mg/l of Aquathol K. The rate of 100% injury was recorded much slower with 1.0 mg/l. With lower concentration O.Smg/1 and 0.1 mg/l, 100% injury was never achieved within 25 days. Therefore, the herbicide was not very effective at lower concentrations