Entropy of Bogoliubov automorphisms of the canonical anticommutation relations

We compute the entropyh _A ( _U ) in the sense of Connes, Narnhofer and Thirring of Bogoliubov automorphisms _U of the CAR-algebra with respect to invariant quasifree states _A with 0A1 having pure point spectrum.Supported in part by a grant from the National Science Foundation     

Laser-supported detonation waves and material processing with pulsed CO2 lasers

Summary The processing of metals with short CO₂ laser pulses is strongly influenced by an air-breakdown plasma (LSD-wave). Material removal is possible only if the duration of this LSD-wave can be kept short compared with the length of the laser pulse. A simple model for the calculation of is developed allowing the derivation of an analytic formula and leading to good agreement with experimental data.

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Zusammenfassung Die Bearbeitung von Metallen mit kurzen CO₂-Laserpulsen wird von einem Air-Breakdown-Plasma (LSD-Welle) stark beeinflusst. Materialabtragung ist nur dann möglich, wenn die Dauer dieser LSD-Welle wesentlich kürzer ist als die gesamte Pulslänge. Es wird ein einfaches Modell für die Berechnung von entwickelt. Daraus lässt sich ein analytischer Ausdruck herleiten. Die Resultate stehen in guter Uebereinstimmung mit experimentellen Daten.

     

Simultaneous determination of ondansetron and tropisetron in human plasma using HPLC with UV detection

A rapid and sensitive HPLC method for the simultaneous quantitation of ondansetron and tropisetron, two serotonin (5-HT) receptor antagonists frequently used in treatment and prevention of nausea and emesis, is described. The procedure involves liquid-liquid extraction of human plasma with dichloromethane coupled with reversed-phase HPLC and UV detection. The lower limits of quantification (LOQ) were 0.62 ng/mL for ondansetron and 1.25 ng/mL or tropisetron. Intra- and inter-assay coefficients of variation ranged from 1.5 to 7.5% and 5.3 to 13.7%, respectively. The sensitivity and precision were sufficient for determination of plasma concentrations after therapeutic administration of both drugs and the method can be used for the estimation of pharmacokinetic parameters.     

Entropy of some automorphisms of theII 1-factor of the free group in infinite number of generators

Summary LetL(F ) be theII ₁-factor defined by the free groupF in infinite number of generators. It is shown that for a class of automorphisms ofL(F ) arising from bijections of the set of generators ofF on itself, and including the free shift, the entropy is zero.Oblatum 15-III-1992     

Take the Right Catalyst: Palladium-Catalyzed C-C, C-N, and C-O Bond Formation on Chloroarenes

Unreactive chloroarenes have been outwitted: The key to successful C-C, C-N, and C-O bond formation on chloroarenes is the development and optimization of suitable catalysts. Electron-rich alkylphosphanes are mandatory as ligands in these palladium-catalyzed reactions.     

The even CAR-algebra

It is shown that the even CAR-algebra over a separable Hilbert space is *-isomorphic to the CAR-algebra.