Parent Stars of Extrasolar Planets. XI. Trends with Condensation Temperature Revisited

We report the results of abundance analyses of new samples of stars with planets and stars without detected planets. We employ these data to compare abundance-condensation temperature trends in both samples. We find that stars with planets have more negative trends. In addition, the more metal-rich stars with planets display the most negative trends. These results confirm and extend the findings of Ramirez et al. (2009) and Melendez et al. (2009), who restricted their studies to solar analogs. We also show that the differences between the solar photospheric and CI meteoritic abundances correlate with condensation temperature.Comment: 7 pages, 11 figures; to be published in MNRA

One-loop partition function of three-dimensional flat gravity

In this note we point out that the one-loop partition function of three-dimensional flat gravity, computed along the lines originally developed for the anti-de Sitter case, reproduces characters of the BMS3 group.Comment: 8 pages. v2: Minor misprints corrected, reference [10] updated. Published in JHE

Regenerative fuel cell study for satellites in GEO orbit

The results of a 12 month study to identify high performance regenerative hydrogen-oxygen fuel cell concepts for geosynchronous satellite application are summarized. Emphasis was placed on concepts with the potential for high energy density and passive means for water and heat management to maximize system reliability. Both polymer membrane and alkaline electrolyte fuel cells were considered, with emphasis on the alkaline cell because of its high performance, advanced state of development, and proven ability to operate in a launch and space environment. Three alkaline system concepts were studied. Results indicate that using near term technology energy densities between 46 and 52 watt-hour/lb can be achieved at efficiencies of 55 percent. Using advanced light weight cell construction which was achieved in experimental cells, composite tankage material for the reactant gases and the reversible stack concept, system energy densities of 115 watt-hours/lb can be projected

Hybrid R&D

We develop a model of R&D competition and collaboration in which individual firms carry out independent in-house research and also undertake joint research projects with other firms. We examine the impact of collaboration on in-house research and explore the circumstances under which a hybrid organization of R&D which combines the two is optimal for firms and society. We find that investments in independent research and in joint research are complementary: an increase in the number of joint projects also increases in-house research. Firm profits are highest under a hybrid organization if the number of firms is small (less than 5) while they are highest with pure in-house research if the number of firms is large (5 or more). However, social welfare is maximized under a hybrid organization of R&D in all cases. Our analysis also yields new results on the role of cooperative R&D. We find that non-cooperative decision making by firms leads to larger R&D investments and higher social welfare than fully cooperative decision making. However, a hybrid form of decision making where there is bilateral cooperation in joint projects and non-cooperative decision making in in-house research yields the highest level of welfare in concentrated industries.

AUGER-HiRes results and models of Lorentz symmetry violation

The implications of AUGER and HiRes results for patterns of Lorentz symmetry violation (LSV) are examined, focusing on weak doubly special relativity (WDSR). If the Greisen-Zatsepin-Kuzmin (GZK) cutoff is definitely confirmed, the mass composition of the highest-energy cosmic-ray spectrum will be a crucial issue to draw precise theoretical consequences from the experimental results. Assuming that the observed flux suppression is due to the GZK mechanism, data will allow in principle to exclude a significant range of LSV models and parameters, but other important possibilities are expected to remain open : Lorentz breaking can be weaker or occur at a scale higher than the Planck scale, unconventional LSV effects can fake the GZK cutoff, threshold phenomena can delay its appearance... Space experiments appear to be needed to further test special relativity. We also examine the consequences of AUGER and HiRes data for superbradyons. If such superluminal ultimate constituents of matter exist in our Universe, they may provide new forms of dark matter and dark energy.Comment: Talk given at the CRIS (Cosmic Ray International Seminar), La Malfa, September 15-19, 2008. To be published in the Proceeding

Master of Science

thesisThe Cambrian Mount Simon Sandstone has been targeted as a major reservoir for CO2 storage in the Illinois Basin. The Mount Simon Sandstone's geologic setting, mature quartz to arkosic composition, reservoir thickness, and generally low permeability of the overlying Eau Claire Formation seal make it an attractive candidate for long-term storage potential of carbon dioxide. Injection of CO2 has been shown to cause a range of chemical alterations that may causes dissolution of existing minerals and precipitation of secondary phases that can alter the porosity and permeability of the reservoir. This study focuses on conducting detailed microscopic analysis of compositionally and texturally dissimilar Mount Simon Sandstone samples from the Illinois Basin that were experimentally exposed to CO2-rich brines for 6 months at the National Energy and Technology Laboratory in collaboration with the Indiana Geological Survey. Our objective is to examine the experimental samples to determine how porosity texture and mineral abundance influence the types of reactions that occur with CO2 injection at various scales. Petrographic and geochemical analysis coupled with Geochemist Workbench's REACT module demonstrates how porosity and permeability amounts strongly influence rates of mineral precipitation and dissolution that occur over the observed 6-month and projected 1000-year period. These results, which represent the compositional and textural heterogeneities in the formation, provide a set of criterion for evaluating CO2 injection sites and long-term storage potential in the formation

Transient [3,3] Cope rearrangement of 3,3-dicyano-1,5-dienes: computational analysis and 2-step synthesis of arylcycloheptanes.

A simple and modular route to arylcycloheptene scaffolds is reported. The two-step route from Knoevenagel adducts and allylic electrophiles is made possible through the design of a Cope rearrangement that utilizes a "traceless" activating group to promote an otherwise thermodynamically unfavorable transformation. Experimentally, the [3,3] rearrangement occurrs transiently at room temperature with a computed barrier of 19.5 kcal mol-1, which ultimately allows for three-component bis-allylation. Ring-closing metathesis delivers the arylcycloheptane and removes the activating group. This report describes the design and optimization of the methodology, scope and mechanistic studies, and computational analysis