Short-Term Dynamical Interactions Among Extrasolar Planets

We show that short-term perturbations among massive planets in multiple planet systems can result in radial velocity variations of the central star which differ substantially from velocity variations derived assuming the planets are executing independent Keplerian motions. We discuss two alternate fitting methods which can lead to an improved dynamical description of multiple planet systems. In the first method, the osculating orbital elements are determined via a Levenberg-Marquardt minimization scheme driving an N-body integrator. The second method is an improved analytic model in which orbital elements are allowed to vary according to a simple model for resonant interactions between the planets. Both of these methods can determine the true masses for the planets by eliminating the sin(i) degeneracy inherent in fits that assume independent Keplerian motions. We apply our fitting methods to the GJ876 radial velocity data (Marcy et al. 2001), and argue that the mass factors for the two planets are likely in the 1.25-2.0 rangeComment: 13 pages, including 4 figures and 3 tables Accepted by Astrophyiscal Journal Letter

A follow-up study of the social adjustment of referred children after group termination

Thesis (M.S.)--Boston Universit

Economic Growth and Threatened and Endangered Species Listings: A VAR Analysis

We conduct several analyses to examine the link between threatened and endangered species listings and macroeconomic activity. Preliminary tests using ordinary least squares are run on both time series data on the national level and cross sectional data at the state level. The analysis is then extended using vector autoregressive (VAR) techniques. VAR results, impulse response functions and variance decompositions are reported to shed more light on the causal relationships between threatened and endangered species, GDP and population. Our results indicate that there is little or no empirical evidence that GDP growth rates lead to changes in the number of threatened and endangered species listings. Key Words: Economic growth, endangered and threatened species, vector autoregression

A follow-up study of the social adjustment of referred children after group termination

Thesis (M.S.)--Boston Universit

Vibration

Physiological and biomechanical responses of humans to vibrations during manned space flight and threshold data on tolerances to various vibrational modes and condition

Stochastic Dominance, Entropy and Biodiversity Management

In this paper we develop a model of population dynamics using the Shannon entropy index, a measure of diversity that allows for global and specific population shocks. We model the effects of increasing the number of parcels on biodiversity, varying the number of spatially diverse parcels to capture risk diversification. We discuss the concepts of stochastic dominance as a means of project selection, in order to model biodiversity returns and risks. Using a Monte Carlo simulation we find that stochastic dominance may be a useful theoretical construct for project selections but it is unable to rank every case. Key Words: Stochastic Dominance, Entropy, Biodiversity Management

A GENERAL, DYNAMIC, SUPPLY-RESPONSE MODEL

Resource /Energy Economics and Policy,

Survival of Terrestrial Planets in the Presence of Giant Planet Migration

The presence of ``Hot Jupiters'', Jovian mass planets with very short orbital periods orbiting nearby main sequence stars, has been proposed to be primarily due to the orbital migration of planets formed in orbits initially much further from the parent star. The migration of giant planets would have profound effects on the evolution of inner terrestrial planets in these systems, and previous analyses have assumed that no terrestrial planets survive after migration has occurred. We present numerical simulations showing that a significant fraction of terrestrial planets could survive the migration process, eventually returning to circular orbits relatively close to their original positions. A fraction of the final orbits are in the Habitable Zone, suggesting that planetary systems with close-in giant planets are viable targets for searches for Earth-like habitable planets around other stars.Comment: 5 pages, 3 figures, emulateapj. ApJL in press, referee comments changes and edited for lengt