A statistical model to estimate refractivity turbulence structure constant C sub n sup 2 in the free atmosphere

A computer program has been tested and documented (Warnock and VanZandt, 1985) that estimates mean values of the refractivity turbulence structure constant in the stable free atmosphere from standard National Weather Service balloon data or an equivalent data set. The program is based on the statistical model for the occurrence of turbulence developed by VanZandt et al. (1981). Height profiles of the estimated refractivity turbulence structure constant agree well with profiles measured by the Sunset radar with a height resolution of about 1 km. The program also estimates the energy dissipation rate (epsilon), but because of the lack of suitable observations of epsilon, the model for epsilon has not yet been evaluated sufficiently to be used in routine applications. Vertical profiles of the refractivity turbulence structure constant were compared with profiles measured by both radar and optical remote sensors and good agreement was found. However, at times the scintillometer measurements were less than both the radar and model values

Computational investigations of low-discrepancy point sets

The quasi-Monte Carlo method of integration offers an attractive solution to the problem of evaluating integrals in a large number of dimensions; however, the associated error bounds are difficult to obtain theoretically. Since these bounds are associated with the L2 discrepancy of the set of points used in the integration. Numerical calculations of the L2 discrepancy for several types of quasi-Monte Carlo formulae are presented

Appraisal of an iterative method for bound states

Iterative method for calculating bound state eigenvalues and properties of radial Schroedinger equatio

The Efficacy and Toxicity of Bupropion in the Elderly

Bupropion is an antidepressant with excellent tolerability and few side effects or drug interactions. These characteristics suite it well for use both in the elderly and in the medically ill. However, early reports of seizures with bupropion therapy in patients with bulimia limited its use. The pharmacology, efficacy, toxicity, and side effect profile of both the immediate release (IR) and the recently available sustained release (SR) formulations of bupropion are reviewed. Bupropion SR is associated with a reduced seizure incidence (0.1%) compared to that found with the IR formulation (0.4%). Recent reports, however, demonstrate that the half-life of bupropion is prolonged in the elderly and that the elderly accumulate bupropion metabolites. Potential toxic effects, including seizures and psychosis, may result from high bupropion plasma levels and the accumulation of bupropion metabolites in the elderly or in those with impaired renal or liver function. Clinical reports in the elderly demonstrate that lower (75-225 mg/day) doses of bupropion are associated with fewer side effects and equal efficacy to that found with higher doses. Bupropion is a good antidepressant choice for the elderly and the medically ill, provided additional precautions, including the use of low doses, are taken. Bupropion should either be avoided or be used with extreme caution in anyone who is at increased risk of seizures or who has a history of psychosis or an eating disorder

Measurement of vertical velocity using clear-air Doppler radars

A new clear air Doppler radar was constructed, called the Flatland radar, in very flat terrain near Champaign-Urbana, Illinois. The radar wavelength is 6.02 m. The radar has been measuring vertical velocity every 153 s with a range resolution of 750 m almost continuously since March 2, 1987. The variance of vertical velocity at Flatland is usually quite small, comparable to the variance at radars located near rough terrain during periods of small background wind. The absence of orographic effects over very flat terrain suggests that clear air Doppler radars can be used to study vertical velocities due to other processes, including synoptic scale motions and propagating gravity waves. For example, near rough terrain the shape of frequency spectra changes drastically as the background wind increases. But at Flatland the shape at periods shorter than a few hours changes only slowly, consistent with the changes predicted by Doppler shifting of gravity wave spectra. Thus it appears that the short period fluctuations of vertical velocity at Flatland are alsmost entirely due to the propagating gravity waves

Finite Density QCD in the Chiral Limit

We present the first results of an exact simulation of full QCD at finite density in the chiral limit. We have used a MFA (Microcanonical Fermionic Average) inspired approach for the reconstruction of the Grand Canonical Partition Function of the theory; using the fugacity expansion of the fermionic determinant we are able to move continuously in the ($\beta -\mu$) plane with $m=0$.Comment: 3 pages, LaTeX, 3 figures, uses espcrc2.sty, psfig. Talk presented by A. Galante at Lattice 97. Correction of some reference

A new class of random number generators required for advanced computer architectures. Revision 1

This is the final report of a three-year, Laboratory-Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). The advent of ever more powerful computers allows one to run Monte Carlo computations of unprecedented length. Currently used random number generators (RNGs) do not have the cycle length necessary for these computations. It is possible to cycle completely through most RNGs used on workstations in a few minutes computations. Even having a long period may not qualify a RNG as suitable. We are developing tests that will allow us to develop high quality RNGs for use in long computations

A new class of random number generators required for advanced computer architectures

This is the final report of a three-year, Laboratory-Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). The advent of ever more powerful computers allows one to run Monte Carlo computations of unprecedented length. Currently used random number generators (RNGs) do not have the cycle length necessary for these computations. It is possible to cycle completely through most RNGs used on workstations in a few minutes computations. Even having a long period may not qualify a RNG as suitable. The authors are developing tests that will allow them to develop high quality RNGs for use in long computations

Closing the gap between palaeontological and neontological speciation and extinction rate estimates.

Measuring the pace at which speciation and extinction occur is fundamental to understanding the origin and evolution of biodiversity. Both the fossil record and molecular phylogenies of living species can provide independent estimates of speciation and extinction rates, but often produce strikingly divergent results. Despite its implications, the theoretical reasons for this discrepancy remain unknown. Here, we reveal a conceptual and methodological basis able to reconcile palaeontological and molecular evidence: discrepancies are driven by different implicit assumptions about the processes of speciation and species evolution in palaeontological and neontological analyses. We present the "birth-death chronospecies" model that clarifies the definition of speciation and extinction processes allowing for a coherent joint analysis of fossil and phylogenetic data. Using simulations and empirical analyses we demonstrate not only that this model explains much of the apparent incongruence between fossils and phylogenies, but that differences in rate estimates are actually informative about the prevalence of different speciation modes