Joint statistics of acceleration and vorticity in fully developed turbulence

We report results from a high resolution numerical study of fluid particles transported by a fully developed turbulent flow. Single particle trajectories were followed for a time range spanning more than three decades, from less than a tenth of the Kolmogorov time-scale up to one large-eddy turnover time. We present results concerning acceleration statistics and the statistics of trapping by vortex filaments conditioned to the local values of vorticity and enstrophy. We distinguish two different behaviors between the joint statistics of vorticity and centripetal acceleration or vorticity and longitudinal acceleration.Comment: 8 pages, 6 figure

Design and Development of a SNAP-8 Mercury Pump Motor Assembly

Design and performance of mercury pump motor for SNAP 8 electrical generato

Effects of whey products on performance of weaned pigs

Three trials were conducted utilizing 458 pigs with an average age of 21 days to study the effects of adding whole whey, or partially delactosed whey from two sources in the diet of weaned pigs on growth, feed intake, and feed efficiency. Additionally, the optimum length of time to feed whole whey and the relationship of age at weaning and addition of whey to the diet were studied. The addition of whey to the diets increased performance of the pigs by 2 to 3 pounds at 8 weeks of age. Pigs fed 20% whole whey diets for 2 weeks performed similarly as those fed 20% whole whey for 5 weeks. No differer1ces were observed between pigs fed whole whey and partially delactosed whey diets. Partially delactosed whey from two different sources produced similar pig performance. Pigs weaned at 3 and 5 weeks performed similarly and out-performed those weaned at 2 weeks. Pigs fed 20% whole whey (weaned at 2, 3, 4, or 5 weeks) outperformed pigs fed the control diet.; Swine Day, Manhattan, KS, November 11, 198

Polyfluorene as a model system for space-charge-limited conduction

Ethyl-hexyl substituted polyfluorene (PF) with its high level of molecular disorder can be described very well by one-carrier space-charge-limited conduction for a discrete set of trap levels with energy $\sim$ 0.5 eV above the valence band edge. Sweeping the bias above the trap-filling limit in the as-is polymer generates a new set of exponential traps, which is clearly seen in the density of states calculations. The trapped charges in the new set of traps have very long lifetimes and can be detrapped by photoexcitation. Thermal cycling the PF film to a crystalline phase prevents creation of additional traps at higher voltages.Comment: 13 pages, 4 figures. Physical Review B (accepted, 2007

Gauged Six-dimensional Supergravity from Massive Type IIA

We obtain the complete non-linear Kaluza-Klein ansatz for the reduction of the bosonic sector of massive type IIA supergravity to the Romans F(4) gauged supergravity in six dimensions. The latter arises as a consistent warped S^4 reduction.Comment: Latex, 7 page

A Minimalist Turbulent Boundary Layer Model

We introduce an elementary model of a turbulent boundary layer over a flat surface, given as a vertical random distribution of spanwise Lamb-Oseen vortex configurations placed over a non-slip boundary condition line. We are able to reproduce several important features of realistic flows, such as the viscous and logarithmic boundary sublayers, and the general behavior of the first statistical moments (turbulent intensity, skewness and flatness) of the streamwise velocity fluctuations. As an application, we advance some heuristic considerations on the boundary layer underlying kinematics that could be associated with the phenomenon of drag reduction by polymers, finding a suggestive support from its experimental signatures.Comment: 5 pages, 10 figure

Variant N=(1,1) Supergravity and (Minkowski)_4 x S^2 Vacua

We construct the fermionic sector and supersymmetry transformation rules of a variant N=(1,1) supergravity theory obtained by generalized Kaluza-Klein reduction from seven dimensions. We show that this model admits both (Minkowski)_4 x S^2 and (Minkowski)_3 x S^3 vacua. We perform a consistent Kaluza-Klein reduction on S^2 and obtain D=4, N=2 supergravity coupled to a vector multiplet, which can be consistently truncated to give rise to D=4, N=1 supergravity with a chiral multiplet.Comment: Latex, 17 pages. Version appearing in Classical and Quantum Gravit