Harmonic maps into loop spaces eliminate of compact Lie groups

We study harmonic maps from Riemann surfaces M to the loop spacesΩG of compact Lie groups G,using the twistor approach.We conjecture that harmonic maps of the Riemann sphere CP~1 intoΩG are related to Yang-Mills G-fields on R~4.     

Resveratrol Tetramers from the Roots of Ampelopsis sinica

Various biological activities of stilbenoids have been described, such as antifungal and antibacterial activities1, antihepatotoxic activity2-4, anti-HIV activity5. Stilbenoids mainly existed in Vitaceae, Diperocarpaceae, Gnetaceae, Cyperaceae, Leguminase1. Many oligostilbenes have been isolated from Vitaceaeous plants. But, there was no report on the stilbenoids in Ampelopsis sinica (Miq.) W. T. Wang which was traditionari- ly used to treat arthritis6. In our study on the constituen…     

Some open combinatorial problems in the design of stated choice experiments

Stated choice experiments are widely used in many areas and the optimal allocation of options to choice sets can make a substantial difference to the cost of running such an experiment. In this paper we describe some open problems in the design of optimal stated choice experiments.     

Investigation of capillary electrophoresis-laser induced fluorescence as a tool in the characterization of sewage effluent for fluorescent acids: determination of salicylic acid

The investigation of emerging contaminant issues is a proactive effort in environmental analysis. As a part of this effort, sewage effluent is of current analytical interest because of the presence of pharmaceuticals and their metabolites and personal care products. The environmental impact of these components is still under investigation but their constant perfusion into receiving waters and their potential effect on biota is of concern. This paper examines a tool for the characterization of sewage effluent using capillary electrophoresis-laser induced fluorescence (CE-LIF) with a frequency-doubled laser operated in the ultraviolet (UV). Fluorescent acidic analytes are targeted because they present special problems for techniques such as gas chromatography-mass spectrometry (GC-MS) but are readily accessible to CE-LIF. As an example of the application of this tool, salicylic acid is determined near the 100 ng/L (7 x 10(-10) M) level in sewage effluent. Salicylic acid is a metabolite of various analgesics. Relatively stable in the environment, it is a common contaminant of municipal sewage systems. Salicylic acid was recovered from freshly collected samples of the effluent by liquid-liquid extraction. Confirmation of identity was by electron ionization GC-MS after conversion of the salicylic acid to the methyl ester by means of trimethylsilyldiazomethane. CE-LIF in the UV has revealed more than 50 individual peaks in the extract and a background response that suggests a large and indeterminate number of additional compounds are present. These data together with complementary techniques provide information on the complexity and components in these effluent streams.     

An analysis and comparison of the time accuracy of fractional‐step methods for the Navier–Stokes equations on staggered grids

Fractional‐step methods solve the unsteady Navier–Stokes equations in a segregated manner, and can be implemented with only a single solution of the momentum/pressure equations being obtained at each time step, or with the momentum/pressure system being iterated until a convergence criterion is attained.The time accuracy of such methods can be determined by the accuracy of the momentum/pressure coupling, irrespective of the accuracy to which the momentum equations are solved. It is shown that the time accuracy of the basic projection method is first‐order as a result of the momentum/pressure coupling, but that by modifying the coupling directly, or by modifying the intermediate velocity boundary conditions, it is possible to recover second‐order behaviour. It is also shown that pressure correction methods, implemented in non‐iterative or iterative form and without special boundary conditions, are second‐order in time, and that a form of the non‐iterative pressure correction method is the most efficient for the problems considered. Copyright © 2002 John Wiley & Sons, Ltd.     

The direct spectropolarimetric titration of palladium(II) ion with d-(-)-1,2-propylenediaminetetraacetic acid

A direct spectropolarimetric titration of palladium(II) at 40°C with the optically active ligand D-(—)-1,2-propylenediaminetetraacetic acid (D(—)PDTA) is described. The optical rotation is monitored with a modified photoelectric polarimeter, and both the palladium-D(—)PDTA complex and the titrant serve as optically active indicators. End-points are obtained by extrapolations. The proposed titration is compared with the visual back-titration method.     

Dualizations and Antipodes

Because an exact pairing between an object and its dual is extraordinarily natural in the object, ideas of R. Street apply to yield a definition of dualization for a pseudomonoid in any autonomous monoidal bicategory as base; this is an improvement on Day and Street, Adv. in Math. 129 (1997), Definition 11, p. 114. We analyse the dualization notion in depth. An example is the concept of autonomous (which, usually in the presence of a symmetry, also has been called rigid or compact) monoidal category. The antipode of a quasi-Hopf algebra H in the sense of Drinfeld is another example obtained using a different base monoidal bicategory. We define right autonomous monoidal functors and their higher-dimensional analogue. Our explanation of why the category Comod _f (H) of finite-dimensional representations of H is autonomous is that the Comod _f operation is autonomous and so preserves dualization.     

Luminescence of exciton in GeS

The luminescence of one free and four bound excitons has been investigated in the layer compound GeS. Up to six phonon replicas of the bound excitons are observable. The energies of these phonons are in reasonable agreement with Raman- and IR reflectivity measurements. The luminescence is highly anisotropic and is only seen in the polarization E ∥ a which confirms that the transitions E ∥ b are forbidden. Measurements with E ∥ c were inconclusive because of the difficulties in the sample preparation. Time resolved measurements revealed decay times between 20 nsec and 1.5 μsec for the different bound excitons. One exciton has been identified as bound to a Si impurity. This is the first observation of intentional doping of GeS. Thermal dissociation energies for the bound excitons lie between 6.5 and 20 meV.