An image system and surface singularity solutions for potential flow past an elliptical cylinder

The Milne-Thomson circle theorem is extended to give a simplegeneral expression for the image system in an elliptical cylinderintroduced into an otherwise specified unbounded potential flowwhich contains no singularities in the region to be occupiedby the ellipse. This image system is used to obtain an expressionfor the corresponding source-sink surface singularity distributionon the ellipse, thus providing new benchmark test cases forsource-sink solutions as obtained numerically by a panel method.Several typical examples are given to illustrate the generaltheoretical approach.     

Quantum pharmacological studies on antimalarial drugs

Summary Linear models for the relation between electronic structure and antimalarial activity of chloroquine drugs have been investigated, based on CNDO/2 molecular orbital calculations. The results indicate that changes in electron density on the atoms N1, N2, C4, C9, and C10 have the strongest influence on the pharmacological activity, so that these atoms can be assumed to form the main active center of these drugs. Correlations improve, if substitution on the nucleus of chloroquine and side chain variations are treated separately. The models found seem to be a useful tool for designing new drugs within the chloroquine series.

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Quantenchemisch-pharmakologische Untersuchungen von Antimalaria-Wirkstoffen

Zusammenfassung Auf der Basis von CNDO/2-Rechnungen wurden lineare Modelle für die Relation zwischen Elektronenverteilung und der Antimalaria-Aktivität von Chlorochinen untersucht. Es zeigte sich, daß Veränderungen in den Elektronendichten der Atome N1, N2, C4, C9 und C10 den stärksten Einfluß auf die pharmakologische Wirkung haben. Es kann somit angenommen werden, daß diese Atome die hauptsächlich aktiven Zentren der Verbindung sind. Die Korrelation wird verbessert, wenn die Substitution am Chlorochin-Kern und Variationen der Seitenketten separat behandelt werden. Die aufgefundenen Modellvorstellungen sollten ein nützliches Werkzeug zur gezielten Synthese neuer Wirkstoffe innerhalb der Chlorochin-Reihe darstellen.

     

On the numerical radius of matrices and its application to iterative solution methods

Uses of the numerical radius in the analysis of basic iterative solution methods, of the SOR method for quasi-Hermitian positive definite matrices (not being consistently ordered) and of maximal eigenvalues of symmetric positive definite matrices using incomplete block-matrix factorizations are presented.