SpinC quantization in odd dimensions

We define and discuss an extension of the SpinC quantization concept to odd-dimensional manifolds. After that we describe its relation to (the usual) even-dimensional SpinC quantization and how its famous properties like "Quantization commutes with reduction" can be regained in odd dimensions. At the end, we analyze the situation on 3-manifolds and give some examples.Comment: 9 page

Rashba type spin-orbit splitting of quantum well states in ultrathin Pb films

A Rashba type spin-orbit splitting is found for quantum well states formed in ultrathin Pb films on Si(111). The resulting momentum splitting is comparable to what is found for semiconductor heterostructures. The splitting shows no coverage dependency and the sign of the spin polarization is reversed compared to Rashba splitting in the Au(111) surface state. We explain our results by competing effects at the two boundaries of the Pb layer

Controlling the effective mass of quantum well states in Pb/Si(111) by interface engineering

The in-plane effective mass of quantum well states in thin Pb films on a Bi reconstructed Si(111) surface is studied by angle-resolved photoemission spectroscopy. It is found that this effective mass is a factor of three lower than the unusually high values reported for Pb films grown on a Pb reconstructed Si(111) surface. Through a quantitative low-energy electron diffraction analysis the change in effective mass as a function of coverage and for the different interfaces is linked to a change of around 2% in the in-plane lattice constant. To corroborate this correlation, density functional theory calculations were performed on freestanding Pb slabs with different in-plane lattice constants. These calculations show an anomalous dependence of the effective mass on the lattice constant including a change of sign for values close to the lattice constant of Si(111). This unexpected relation is due to a combination of reduced orbital overlap of the 6p_z states and altered hybridization between the 6p_z and 6p_xy derived quantum well states. Furthermore it is shown by core level spectroscopy that the Pb films are structurally and temporally stable at temperatures below 100 K.Comment: 7 pages, 6 figure

Pflegerische Interventionen zur Vermeidung erneuter depressiver Episoden

In der Schweiz erkranken pro Jahr rund 7% der Bevölkerung erstmalig oder erneut an einer unipolaren Depression. Das Risiko einer erneuten depressiven Episode liegt bei 50% und erhöht sich bei jeder Episode. Während die medikamentöse Therapie sowie die Psychotherapie klar definiert und die Grundlagen erforscht sind, sind pflegerischen Interventionen zur Prävention erneuter depressiver Episoden erst ungenügend erfasst und erforscht. Für die Beantwortung der Fragestellung wurde eine systematisierte Literaturrecherche in den Datenbanken PubMed, CINAHL und PsyInfo durchgeführt. Die gefundenen Studien wurden anhand des EBN-Modells nach Raycroft-Malone analysiert. Fünf quantitative Studien wurden selektionierten, jeweils eine in den Themenbereichen Psychoedukation, Telemedizin, Selbsthilfemanagement und zwei Studien im Bereich E-Health geclustert. Klare Forschungsergebnisse lieferte nur die Studie im Bereich Selbsthilfemanagement. Hier mussten Betroffene selbständig ein SelbsthilfeBuch erarbeiten parallel zu einem telefonischen Einzel-Support. Um erneute depressive Episoden zu verhindern, müssen Interventionen gefunden werden, die nicht nur die Anzahl depressiver Episoden, sondern auch die alltägliche Symptomlast der Betroffenen reduzieren. Dazu müssen Forschungslücken im Bereich der Patientenzufriedenheit, der gesundheitlichen Risiken der Interventionen und der wirtschaftlichen Faktoren geschlossen werden

Defect healing at room temperature in pentacene thin films and improved transistor performance

We report on a healing of defects at room temperature in the organic semiconductor pentacene. This peculiar effect is a direct consequence of the weak intermolecular interaction which is characteristic of organic semiconductors. Pentacene thin-film transistors were fabricated and characterized by in situ gated four-terminal measurements. Under high vacuum conditions (base pressure of order 10E-8 mbar), the device performance is found to improve with time. The effective field-effect mobility increases by as much as a factor of two and mobilities up to 0.45 cm2/Vs were achieved. In addition, the contact resistance decreases by more than an order of magnitude and there is a significant reduction in current hysteresis. Oxygen/nitrogen exposure and annealing experiments show the improvement of the electronic parameters to be driven by a thermally promoted process and not by chemical doping. In order to extract the spectral density of trap states from the transistor characteristics, we have implemented a powerful scheme which allows for a calculation of the trap densities with high accuracy in a straightforward fashion. We show the performance improvement to be due to a reduction in the density of shallow traps <0.15 eV from the valence band edge, while the energetically deeper traps are essentially unaffected. This work contributes to an understanding of the shallow traps in organic semiconductors and identifies structural point defects within the grains of the polycrystalline thin films as a major cause.Comment: 13 pages, 13 figures, to be published in Phys. Rev.