Holonomy groups,complex structures andD=4 topological Yang-Mills theory

We study conditions for the existence of extended supersymmetry in topological Yang-Mills theory. These conditions are most conveniently formulated in terms of the holonomy group of the underlying manifold, on which the topological Yang-Mills theory is defined. For irreducible manifolds we find that extended supersymmetries are in 1–1 correspondence with covariantly constant complex structures. Therefore, the topological Yang-Mills theory on any Kähler manifold possesses one additional supersymmetry and on any hyper Kähler manifold there are three additional supersymmetries. The Donaldson map, which plays a crucial role in the construction of the topological invariants, is generalized for Kähler manifolds, thus providing candidates for new invariants of complex manifolds.     

Nonscalarized multiobjective global optimization

A new approach to multiobjective optimization is presented which is made possible due to our ability to obtain full global optimal solutions. A distinctive feature of this approach is that a vector cost function is nonscalarized. The method provides a means for the solution of vector optimization problems with nonreconcilable objectives.This work was supported by the Natural Sciences and Engineering Research Council of Canada, Grant No. A3492.     

Uncertainty principles as embeddings of modulation spaces

A class of new uncertainty principles is derived in the form of embeddings of Fourier-Lebesgue spaces into modulation spaces. These embeddings provide practical, sufficient conditions for a function to belong to a modulation space. Counterexamples based on the properties of Gabor expansions demonstrate that the embeddings are optimal.     

Molekular- und Zusammensetzungsheterogenit?t der Copolymerisate der Methacryls?ure mit Styrol

Ohne Zusammenfassung     

Coherently controlled molecular junctions

Within a generic model, we discuss the possibility of coherent control of charge fluxes in unbiased molecular junctions. The control is induced by resonances between the Rabi frequency due to a pumping laser field and internal characteristic frequencies of pre-designed molecular donor-bridge-acceptor complexes. Two models are considered: a coherently controlled molecular charge pump and a molecular switch. The study generalizes previous consideration of light induced current [M. Galperin and A. Nitzan, Phys. Rev. Lett. 95, 206802 (2005)] and of a molecular electron pump [R. Volkovich and U. Peskin, Phys. Rev. B 83, 033403 (2011)] and accounts for the coherently driven charge transport in an unbiased molecular junction with symmetric coupling to leads. Numerical examples demonstrate the feasibility of the control mechanism for realistic junctions parameters.     

Conducting properties of In2O3:Sn thin films at low temperatures

Electrical conductivity, Hall effect and magnetoresistance of In₂O₃:Sn thin films deposited on a glass substrates at different temperatures and oxygen pressures, have been investigated in the temperature range 4.2–300 K. The observed temperature dependences of resistivity for films deposited at 230 °C as well as at nominally room temperatures were typical for metallic transport of electrons except temperature dependence of resistivity of the In₂O₃:Sn film deposited in the oxygen deficient atmosphere. The electrical measurements were accompanied by AFM and SEM studies of structural properties, as well as by XPS analysis. It is established that changes of morphology and crystallinity of ITO films modify the low-temperature behavior of resistivity, which still remains typical for metallic transport. This is not the case for the oxygen deficient ITO layer. XPS analysis shows that grown in situ oxygen deficient ITO films have enhanced DOS between the Fermi level and the valence band edge. The extra localized states behave as acceptors leading to a compensation of n-type ITO. That can explain lower n-type conductivity in this material crossing over to a Mott-type hopping at low temperatures. Results for the low temperature measurements of stoichiometric ITO layers indicate that they do not show any trace of metal-to-insulator transition even at 4.2 K. We conclude that, although ITO is considered as a highly doped wide-band gap semiconductor, its low-temperature properties are very different from those of conventional highly doped semiconductors.     

A second moment closure model for MHD turbulence

A second moment turbulence closure model of the type used before for flows with density stratification, frame rotation and streamline curvature is augmented to describe MHD flows with small magnetic Reynolds number. It is shown that all three configurations of the constant unidirectional magnetic field (longitudinal, transverse and azimuthal) suppress the components of the Reynolds stress tensor as well as turbulence energy. Criterions are derived for the extinction of 3-D turbulence based on magnetic Richardson numbers. Monin-Obukhov type similarity theory is developed for MHD turbulent flows. The combined effect of longitudinal magnetic field and spanwise rotation is considered. A discussion is presented on the extra strains exerted by the electromagnetic force compared to the effects of buoyancy, frame rotation and streamline curvature.

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Zusammenfassung Ein Turbulenzmodell mit Schlieung zweiter Ordnung, das bisher für Strömungen mit Dichteschichtung, rotierenden Bezugssystem und gekrümmten Stromlinien benutzt wurde, wird hier zur Beschreibung von MHD-Strömungen mit kleiner magnetischer Reynoldszahl erweitert. Es wird gezeigt, da alle drei Anordnungen eines konstanten, in einer Richtung verlaufenden Magnetfeldes (longitudinal, transversal und azimuthal) sowohl die Komponenten des Reynoldsschen Schubspannungstensors als auch die turbulente Energie reduzieren. Es werden Kriterien für die Auslöschung der 3D-Turbulenz abgeleitet, die auf der magnetischen Richardsonzahl beruhen, Für turbulente MHD-Strömungen wird eine Ähnlichkeitstheorie vom Monin-Obukhov Typ entwickelt. Der kombinierte Effekt von longitudinalen Magnetfeld und Rotation senkrecht zur Strömungsrichtung wird betrachtet. Die durch die elektromagnetische Kraft bewirkte zusätzliche Deformation wird im Vergleich zu den Effekten von Auftrieb, Rotation des Bezugssystems und Krümmung der Stromlinien diskutiert.