The RELAP5-3D (version bt) computer program was used to assess a GE level swell experiment. The primary goal of the new assessment models was to faithfully represent the experimental facility and instrumentation. In developing the new models, a non-physical representation of the vessel heads in a previous assessment was found. This distortion resulted in predictions that closely matched the experimental data, but were in error. The new assessment also highlighted an instability in the calculation of interfacial drag. To explore this issue, analyses were performed using three different interfacial drag correlations appropriate for large diameter pipes and/or vessels. The results of this study show that the Kataoka-Ishii correlation, which is currently used in RELAP5-3D, compares most favorably with the experimental data. Additionally, a numerical instability was uncovered with the analysis performed using the Gardner correlation and was traced to the calculation of bubble diameter in the bubbly flow regime.

The authors evaluated the sensitivity of a habitat model and a source-sink population model to spatial uncertainty in landscapes with different statistical properties and for hypothetical species with different habitat requirements. Sequential indicator simulation generated alternative landscapes from a source map. Their results showed that spatial uncertainty was highest for landscapes in which suitable habitat was rare and spatially uncorrelated. Although, they were able to exert some control over the degree of spatial uncertainty by varying the sampling density drawn from the source map, intrinsic spatial properties (i.e., average frequency and degree of spatial autocorrelation) played a dominant role in determining variation among realized maps. To evaluate the ecological significance of landscape variation, they compared the variation in predictions from a simple habitat model to variation among landscapes for three species types. Spatial uncertainty in predictions of the amount of source habitat depended on both the spatial life history characteristics of the species and the statistical attributes of the synthetic landscapes. Species differences were greatest when the landscape contained a high proportion of suitable habitat. The predicted amount of source habitat was greater for edge-dependent (interior) species in landscapes with spatially uncorrelated(correlated) suitable habitat. A source-sink model demonstrated that, although …

The calculation of QCD corrections to the width difference {Delta}{Lambda} in the B{sub s}meson system is presented. The next-to-leading order corrections reduce the dependence on the renormalization scale significantly and allow for a meaningful use of hadronic matrix elements from lattice gauge theory. At present the uncertainty of the lattice calculations limits the prediction of {Delta}{Lambda}. The presented work has been performed in collaboration with Martin Beneke, Gerhard Buchalla, Christoph Greub and Alexander Lenz.

In the literature, one often finds calculations of (e,e{prime}p) reactions at GeV energies using the factorization approach. Factorization implies that the differential cross section can be written as the product of an off-shell electron-proton cross section and a distorted missing momentum distribution. While this factorization appears in the non-relativistic plane wave impulse approximation, it is broken in a more realistic approach. The main source of factorization breaking are final state interactions. In this paper, sources of factorization breaking are identified and their numerical relevance is examined in the reaction {sup 2}H(e,e{prime}p) for various kinematic settings in the GeV regime. The results imply that factorization should not be used for precision calculations, especially as unfactorized calculations are available.