We give numerical benchmark results for particle transport in a randomly mixed binary medium, with the mixing statistics described as a homogeneous Markov process. A Monte Carlo procedure is used to generate a physical realization of the statistics, and a discrete ordinate numerical transport solution is generated for this realization. The ensemble averaged solution, as well as the variance, is obtained by averaging a large number of such calculations. Reflection and transmission results are given for several problems in both rod and planar geometry. In a separate development, two coupled transport equations are derived which formally describe transport in a random binary mixture for arbitrary mixing statistics. Closing these equations by approximating their coupling terms in a low order and intuitive way leads to a model for stochastic transport previously obtained via the master equation. The present derivation, based upon approximating exact equations, allows in principle the opportunity to develop more accurate models by making higher order approximations in the coupling terms.
A gas chromatographic (GC) method has been developed for determination of cholesterol in meats. The method involves (a) ethanolic KOH saponification of the sample material, (b) homogeneous-phase toluene extraction of the unsaponifiables, (c) derivatization of cholesterol to its trimethylsilylether, and (d) quantitation by GC-flame ionization detection using 5-α-cholestane as internal standard. This direct saponification method is compared with the current AOAC official method for determination of cholesterol in 20 different meat products. The direct saponification method eliminates the need for initial lipid extraction, thus offering a 30% savings in labor, and requires fewer solvents than the AOAC method. It produced comparable or slightly higher cholesterol results than the AOAC method in all meat samples examined. Precision, determined by assaying a turkey meat sample 16 times over 4 days, was excellent (CV = 1.74%). Average recovery of cholesterol added to meat samples was 99.8%.
'l'l~e SWYW EcoKI restriction endonuclease cleavage sites in bacteriophage P%d DNA have been mapped. The cleavage site map of circularly permut.ed P22 linear DNA is a circle. The positions of EcoRI sites in the early region of the P22 genomc were determined by comparing products of EcoRI digestion of maturtx liaear P22 chromosomes with the EcoRI cleavage fragments of DNA of three XimmP22 hybrid phages and a P22 deletion mutant. An EcoRI site in the late region was mapped by partial digestion of the P22 deletion mutant DNA. Since the P22 genes included in the himmP22 hybrid phages, and the genet.ic region missing in the P22 deletion mutant are known, some P22 genes can be positioned on this init,ial physical map of the P22 genome relative to EcoRI cleavage sites.
Strong hydrogen line radiation can significantly affect the ionization and energy balance in high-density, lowtemperature edge plasmas. A fully self-consistent one-dimensional simulation code integrating line radiation with edge plasma transport has recently been demonstrated. This code allows us to evaluate the use of approximate treatments of radiation effects that could potentially be incorporated into existing two-dimensional edge plasma codes. For a given approximation, we tabulate effective ionization, recombination and energy loss rates for hydrogen plasmas in a one-dimensional geometry as a function of electron density, temperature and position. The position is a simple parameterization corresponding to optical depth, with the correspondence dependent on plasma properties, including magnetic field. The parameterized values can differ by more than an order of magnitude from the optically thin values.We present one-dimensional edge plasma simulations using the parameterized tables and compare them to self-consistent simulations to investigate the validity of this approach, the effectiveness of the parameterization and the accuracy of the approximations used. We also present results using parameterized tables in a twodimensional code and discuss the validity of applying them in this manner.
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