THE RETURNS TO AGRICULTURAL RESEARCH IN MAINE: THE CASE OF A SMALL NORTHEASTERN EXPERIMENT STATION

Estimates of the marginal internal rate of return to expenditures for research by the Maine Agricultural Experiment Station are presented. Estimates are performed using ridge regression under an array of specifications, including alternative functional forms, lag structures, costs of public funds, and variable specifications. The results are consistent with many previous results that imply an underinvestment in agricultural research.Research and Development/Tech Change/Emerging Technologies,

Possible Effects of a Cosmological Constant on Black Hole Evolution

We explore possible effects of vacuum energy on the evolution of black holes. If the universe contains a cosmological constant, and if black holes can absorb energy from the vacuum, then black hole evaporation could be greatly suppressed. For the magnitude of the cosmological constant suggested by current observations, black holes larger than $\sim 4 \times 10^{24}$ g would accrete energy rather than evaporate. In this scenario, all stellar and supermassive black holes would grow with time until they reach a maximum mass scale of $\sim 6 \times 10^{55}$ g, comparable to the mass contained within the present day cosmological horizon.Comment: LaTex, 9 pages, accepted to Physics Letters

REIT Stock Repurchases: Completion Rates, Long - Run Returns, and the Straddle Hypothesis

This study of real estate investment trusts (REITs) analyzes three possible explanations for the stock price reaction to a repurchase announcement and the subsequent repurchase behavior of managers under each hypothesis. Two of the hypotheses, the signaling hypothesis and the exchange option hypothesis, are established in the existing literature; the third hypothesis is a modification of the exchange option hypothesis. The exchange option hypothesis is extended to allow for additional flexibility in management decisions. This extended exchange option hypothesis is termed the ‘‘straddle’’ hypothesis because it provides management with both a call and put option. The empirical analyses show the straddle hypothesis is a more robust explanation of changes in shares outstanding in the postannouncement period than the alternative explanations.

Relativistic Effects in Extrasolar Planetary Systems

This paper considers general relativistic (GR) effects in currently observed extrasolar planetary systems. Although GR corrections are small, they can compete with secular interactions in these systems and thereby play an important role. Specifically, some of the observed multiple planet systems are close to secular resonance, where the dynamics is extremely sensitive to GR corrections, and these systems can be used as laboratories to test general relativity. For the three-planet solar system Upsilon Andromedae, secular interaction theory implies an 80% probability of finding the system with its observed orbital elements if GR is correct, compared with only a 2% probability in the absence of GR. In the future, tighter constraints can be obtained with increased temporal coverage.Comment: Accepted for publication in International Journal of Modern Physics D; this paper received ``Honorable Mention'' in the 2006 Essay Competition of the Gravity Research Foundation; 9 pages including 1 figur

HYDRAULIC RESPONSE TO EMULSIFIED VEGETABLE OIL BIOSTIMULATION: IN-SITU TEST IN A HIGHLY HETEROGENOUS URANIUM CONTAMINATED AQUIFER

The purpose of this study was to determine if the injection of emulsified vegetable oil (EVO) to remediate a uranium-contaminated aquifer can result in a reduction in hydraulic conductivity. The secondary purpose was to determine if there was evidence of a “memory effect,” a phenomenon where the second time an electron donor is injected, the environment responds to it faster. This has been observed at many remediation sites. A previously treated (2009) uranium contaminated aquifer at Y-12 National Security Complex located in Oak Ridge, Tennessee, was injected with EVO to determine whether hydraulic conductivity changes and to assess the effectiveness of EVO treatment for reducing dissolved uranium. Acetate was monitored in downgradient wells as an indicator of biodegradation. On December 13, 2017, a 20% EVO and groundwater mixture was injected within the Y-12 FRC Area 2 site. Periodic measurements of hydraulic conductivity and dissolved uranium concentration were taken from a control wells, three injection wells, and four down-gradient wells for 134 days. During the experiment, hydraulic conductivity in the injection wells decreased by up to two orders of magnitude but only up to one order of magnitude in half of the down-gradient monitoring wells located 2.5 to 11 m away. Dissolved uranium concentrations significantly decreased in the injection wells, but not in the monitoring well directly down-gradient of injection because dissolved uranium concentrations increased by day 78 and surpassed pre-injection concentrations due to oxidation of reduced uranium in those wells. Acetate concentrations indicated an accelerated response to EVO compared to the 2009 study results. However, this was the only evidence of “memory response.” The results of this study show that injecting EVO can have unintended consequences related to hydraulic conductivity, which can reduce EVO effectiveness or even cause bioremediation using EVO to fail. The effects of EVO interacting with aquifer media and injection well spacing should be carefully considered to minimize changes in preferential flow, limit oxidation of reduced uranium, and maximize the effectiveness of the treatment