Comparison of Models of Critical Opacity in the Quark-Gluon Plasma

In this work we discuss two methods of calculation of quark propagation in the quark-gluon plasma. Both methods make use of the Nambu-Jona-Lasinio model. The essential difference of these calculations is the treatment of deconfinement. A model of confinement is not included in the work of Gastineau, Blanquier and Aichelin [hep-ph/0404207], however, the meson states they consider are still bound for temperatures greater than the deconfinement temperature T_c. On the other hand, our model deals with unconfined quarks and includes a description of the q(bar)q resonances found in lattice QCD studies that make use of the maximum entropy method (MEM). We compare the q{bar)q cross sections calculated in these models.Comment: 7 pages and 4 figures RevTe

Debt and Risk Preference: A Household Level Analysis

We explore the relationship between risk preference and the level of unsecured debt at the household level within the context of a two period theoretical framework, which predicts that debt is a function of risk aversion. We test the predictions of our theoretical framework for a sample of households drawn from the U.S. Panel Study of Income Dynamics (PSID) and the U.S. Survey of Consumer Finances (SCF). Using a sequence of questions from the 1996 PSID and the 1989 to 2004 SCF, we construct measures of risk preference allowing us to explore the implications of interpersonal differences in risk preference for the accumulation of unsecured debt at the household level. Our empirical findings, which accord with our theoretical priors, suggest that risk preference is an important determinant of the level of unsecured debt acquired at the household level with risk aversion serving to reduce the level of unsecured debt accumulated by households

Software for the grouped optimal aggregation technique

The grouped optimal aggregation technique produces minimum variance, unbiased estimates of acreage and production for countries, zones (states), or any designated collection of acreage strata. It uses yield predictions, historical acreage information, and direct acreage estimate from satellite data. The acreage strata are grouped in such a way that the ratio model over historical acreage provides a smaller variance than if the model were applied to each individual stratum. An optimal weighting matrix based on historical acreages, provides the link between incomplete direct acreage estimates and the total, current acreage estimate

Composite engines for application to a single-stage-to-orbit vehicle

Seven composite engines were designed for application to a reusable single-stage-to-orbit vehicle. The engine designs were variations of the supercharged ejector ramjet engine. The resulting performance, weight, and drawings of each engine form a data base for establishing a potential of this class of composite engine to various missions, including the single-stage-to-orbit application. The impact of advanced technology in the design of the critical fan turbine was established