Local scale-invariance in ageing phenomena

Many materials quenched into their ordered phase undergo ageing and there show dynamical scaling. For any given dynamical exponent z, this can be extended to a new form of local scale-invariance which acts as a dynamical symmetry. The scaling functions of the two-time correlation and response functions of ferromagnets with a non-conserved order parameter are determined. These results are in agreement with analytical and numerical studies of various models, especially the kinetic Glauber-Ising model in 2 and 3 dimensions.Comment: Invited talk; spring meeting of the german physical society, Regensburg the 8th of March 2004, 12 pages, style file

Shake-up Processes in Intersubband Magneto-photoabsorption of a Two-Dimensional Electron Gas

I theoretically study shake-up processes in photoabsorption of an interacting low-density two-dimensional electron gas (2DEG) in magnetic fields. Such processes, in which an incident photon creates an electron-hole pair and simultaneously excites one electron to one of the higher Landau levels, were observed experimentally [D.R. Yakovlev et al., Phys. Rev. Lett. 79, 3974 (1997)] and were called combined exciton-cyclotron resonance (ExCR). The recently developed theory of ExCR [A.B. Dzyubenko, Phys. Rev. B 64, 241101 (2001)] allows for a consistent treatment of the Coulomb correlations, establishes the exact ExCR selection rules, and predicts the high field features of ExCR. In this work, I generalize the existing theory of high-field ExCR in the 2DEG to the case when the hole is excited to higher hole Landau levels.Comment: 4 pages, 3 figures; Proceedings NGS-11 (June 2003, Buffalo, NY, USA

Charged Excitons in the Quantum Hall Regime

We review our recent optical experiments on two-dimensional electron systems at temperatures below 1 K and under high magnetic fields. The two-dimensional electron systems are realized in modulation-doped GaAs-AlGaAs single quantum wells. Via gate electrodes the carrier density of the two-dimensional electron systems can be tuned in a quite broad range between about 1×10^{10} cm^{-2} and 2×10^{11} cm^{-2}. In dilute two-dimensional electron systems, at very low electron densities, we observe the formation of negatively charged excitons in photoluminescence experiments. In this contribution we report about the observation of a dark triplet exciton, which is observable at temperatures below 1 K and for electron filling factors <1/3, i.e., in the fractional quantum Hall regime only. In experiments where we have increased the density of the two-dimensional electron systems so that a uniform two-dimensional electron system starts to form, we have found a strong energy anomaly of the charged excitons in the vicinity of filling factor 1/3. This anomaly was found to exist in a very narrow parameter range of the density and temperature, only. We propose a model where we assume that localized charged excitons and a uniform Laughlin liquid coexist. The localized charged exciton in close proximity to the Laughlin liquid leads to the creation of a fractionally-charged quasihole in the liquid, which can account for the experimentally observed anomaly

gg-factor and static quadrupole moment of 135^{135}Pr, 105^{105}Pd, and 187^{187}Au in wobbling motion

The $g$-factor and static quadrupole moment of the nuclides $^{135}$Pr, $^{105}$Pd, and $^{187}$Au in the wobbling motion are investigated in the particle-rotor model as functions of the total spin $I$. The $g$-factor of $^{105}\mathrm{Pd}$ increases with increasing $I$, due to the negative gyromagnetic ratio of a neutron valence-neutron. This behavior is in contrast to the decreasing $g$-factor of the other two nuclides, $^{135}$Pr and $^{187}$Au, which feature a valence-proton. The static quadrupole moment $Q$ depends on all three expectation values of the total angular momentum. It is smaller in the yrast band than in the wobbling band for the transverse wobblers $^{135}$Pr and $^{105}$Pd, while larger for the longitudinal wobbler $^{187}$Au.Comment: 6 pages, 4 figure

Psychologische Prädiktoren für das Auftreten einer Major Depression und einer PTBS nach schweren Unfällen

Theoretischer Hintergrund/Fragestellung: Ziel unserer prospektiven Studie war die Identifikation von Prädiktoren für das Auftreten einer Depression im ersten halben Jahr nach einem Unfall. Methode: Es wurden 52 Unfallpatienten untersucht. Die Ersterhebung erfolgte innerhalb der ersten sechs Wochen nach dem Unfall. Ergebnisse: Depressive Patienten gaben kurz nach dem Unfall eine geringere Lebenszufriedenheit und soziale Unterstützung an und berichteten häufiger über psychische Störungen und traumatische Erlebnisse vor dem Unfall als Nicht-Depressive. Außerdem litten sie zum Zeitpunkt der Ersterhebung häufiger unter psychischen Störungen und fühlten sich durch die psychischen Symptome stärker beeinträchtigt. Schlussfolgerung: Die Ergebnisse legen nahe, dass Patienten mit einem Risiko für die Entwicklung einer Depression bereits kurz nach einem Unfall identifiziert werden können

Onset and maintenance of psychiatric disorders after serious accidents

The purpose of this study was to prospectively investigate the onset, course, and remission of psychiatric disorders in the first 6months after a serious accident for consecutive patients in a hospital emergency department. Participants were 58 patients aged 18-65 who were assessed shortly after attending a hospital emergency department and were followed up 6months afterwards. Patients were interviewed with regard to past and current psychiatric history using different instruments (e.g. SCID for DSM-IV). Prior to their accidents, 35% of all subjects had experienced one or more psychiatric disorders (lifetime prevalence). Shortly after the accident, the incidence of Acute Stress Disorder (7%), subsyndromal Acute Stress Disorder (12%), and adjustment disorder (1.5%) was increased as a reaction to the accident. At this time, 29% of all patients suffered from an acute psychiatric disorder. Six-months after the accident, 10% of the subjects met criteria for Major Depression, 6% for PTSD, 4% for subsyndromal PTSD, and 1.5% for Specific Phobia as newly developed disorders. The course of the psychiatric disorders shows that those patients who met criteria for any psychiatric diagnosis shortly after the accident ran a much higher risk for developing new or comorbid psychiatric disorders in the futur