Ab initio many-body calculation of excitons in solid Ne and Ar

Absorption spectra, exciton energy levels and wave functions for solid Ne and Ar have been calculated from first principles using many-body techniques. Electronic band structures of Ne and Ar were calculated using the GW approximation. Exciton states were calculated by diagonalizing an exciton Hamiltonian derived from the particle-hole Green function, whose equation of motion is the Bethe-Salpeter equation. Singlet and triplet exciton series up to n=5 for Ne and n=3 for Ar were obtained. Binding energies and longitudinal-transverse splittings of n=1 excitons are in excellent agreement with experiment. Plots of correlated electron-hole wave functions show that the electron-hole complex is delocalised over roughly 7 a.u. in solid Ar.Comment: 6 page

Coupling/decoupling between translational and rotational dynamics in a supercooled molecular liquid

We use molecular dynamics computer simulations to investigate the coupling/decoupling between translational and rotational dynamics in a glass-forming liquid of dumbbells. This is done via a careful analysis of the $\alpha$-relaxation time $\tau_{q^{*}}^{\rm C}$ of the incoherent center-of-mass density correlator at the structure factor peak, the $\alpha$-relaxation time $\tau_{2}$ of the reorientational correlator, and the translational ($D_{t}$) and rotational ($D_{r}$) diffusion constants. We find that the coupling between the relaxation times $\tau_{q^{*}}^{\rm C}$ and $\tau_{2}$ increases with decreasing temperature $T$, whereas the coupling decreases between the diffusivities $D_{t}$ and $D_{r}$. In addition, the $T$-dependence of $D_{t}$ decouples from that of $1/\tau_{2}$, which is consistent with previous experiments and has been interpreted as a signature of the "translation-rotation decoupling." We trace back these apparently contradicting observations to the dynamical heterogeneities in the system. We show that the decreasing coupling in the diffusivities $D_{t}$ and $D_{r}$ is only apparent due to the inadequacy of the concept of the rotational diffusion constant for describing the reorientational dynamics in the supercooled state. We also argue that the coupling between $\tau_{q^{*}}^{\rm C}$ and $\tau_{2}$ and the decoupling between $D_{t}$ and $1/\tau_{2}$, both of which strengthen upon cooling, can be consistently understood in terms of the growing dynamic length scale.Comment: revised manuscript, to appear in Phys. Rev. Let

Psychiatrische Versorgungsepidemiologie

Zusammenfassung: Psychiatrische Versorgungsepidemiologie untersucht die Situation der Versorgung von Menschen mit psychischen Erkrankungen unter Alltagsbedingungen. Psychiatrische Versorgungsstrukturen in Deutschland haben sich in den letzten Jahrzehnten weg von stationärer Behandlung mit teilweise mehrmonatiger Aufenthaltsdauer hin zu dezentralen teilstationären und ambulanten Angeboten entwickelt. Derzeit hat sich die Verschiebung von Behandlungskapazitäten zwischen den Settings stabilisiert und der Schwerpunkt der Versorgungsplanung liegt mehr auf der Entwicklung von möglichst flächendeckenden Strukturen zur Vernetzung der oftmals noch fragmentierten und streng an den Sektorgrenzen orientierten Versorgungslandschaft. Der Versorgungsbedarf hängt mit einer Vielzahl Faktoren wie den epidemiologischen Daten der Bevölkerung, der Inanspruchnahme und den gesundheitspolitischen Rahmenbedingungen zusammen. Ob die derzeitigen Versorgungsstrukturen den aktuellen Bedarf abdecken und den Qualitätsansprüchen genügen, ist aufgrund der spärlichen Datenlage und dem Mangel an Referenzmaßstäben nur schwer zu beurteilen. Ein substanzieller Ausbau psychiatrischer Versorgungsforschung in den kommenden Jahren ist hierfür grundlegend erforderlic

Irreversibility on the Level of Single-Electron Tunneling

We present a low-temperature experimental test of the fluctuation theorem for electron transport through a double quantum dot. The rare entropy-consuming system trajectories are detected in the form of single charges flowing against the source-drain bias by using time-resolved charge detection with a quantum point contact. We find that these trajectories appear with a frequency that agrees with the theoretical predictions even under strong nonequilibrium conditions, when the finite bandwidth of the charge detection is taken into account

Magnetic Miniband Structure and Quantum Oscillations in Lateral Semiconductor Superlattices

We present fully quantum-mechanical magnetotransport calculations for short-period lateral superlattices with one-dimensional electrostatic modulation. A non-perturbative treatment of both magnetic field and modulation potential proves to be necessary to reproduce novel quantum oscillations in the magnetoresistance found in recent experiments in the resistance component parallel to the modulation potential. In addition, we predict oscillations of opposite phase in the component perpendicular to the modulation not yet observed experimentally. We show that the new oscillations originate from the magnetic miniband structure in the regime of overlapping minibands.Comment: 6 pages with 4 figure

Local prediction of turning points of oscillating time series

For oscillating time series, the prediction is often focused on the turning points. In order to predict the turning point magnitudes and times it is proposed to form the state space reconstruction only from the turning points and modify the local (nearest neighbor) model accordingly. The model on turning points gives optimal prediction at a lower dimensional state space than the optimal local model applied directly on the oscillating time series and is thus computationally more efficient. Monte Carlo simulations on different oscillating nonlinear systems showed that it gives better predictions of turning points and this is confirmed also for the time series of annual sunspots and total stress in a plastic deformation experiment.Comment: 7 pages, 5 figures, 2 tables, submitted to PR