Parallel information-based complexity

We develop the theory of information-based complexity from a parallel point of view. For a model of computation with p processors, each being capable of arithmetic operations and decisions, we analyze the complexity of function approximation, numerical integration, and solution of Fredholm integral equations. We obtain tight bounds on the complexity, considered as a function of three variables simultaneously: the number of processors, the required precision, and (in the case of approximation and integral equations) the number of points, in which the approximate solution is to be determined.     

Über die Bestimmung der Verzweigungspunkte eines hyperelliptischen Integrals aus seinen Periodizitätsmoduln mit Anwendungen auf die Theorie des Transformators

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Ein kurzer Beweis des Angelic-Satzes für stetige Funktionen auf web-kompakten Räumen

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Photoluminescence properties of Co-doped ZnO nanocrystals

We performed photoluminescence experiments on colloidal, Co²⁺-doped ZnO nanocrystals in order to study the electronic properties of Co²⁺ in a ZnO host. Room temperature measurements showed, next to the ZnO exciton and trap emission, an additional emission related to the Co²⁺ dopant. The spectral position and width of this emission does not depend on particle size or Co²⁺ concentration. At 8 K, a series of ZnO bulk phonon replicas appear on the Co²⁺-emission band. We conclude that Co²⁺ ions are strongly localized in the ZnO host, making the formation of a Co²⁺d-band unlikely. Magnetic measurements revealed a paramagnetic behaviour.