Spin-Boson Hamiltonian and Optical Absorption of Molecular Dimers

An analysis of the eigenstates of a symmetry-broken spin-boson Hamiltonian is performed by computing Bloch and Husimi projections. The eigenstate analysis is combined with the calculation of absorption bands of asymmetric dimer configurations constituted by monomers with nonidentical excitation energies and optical transition matrix elements. Absorption bands with regular and irregular fine structures are obtained and related to the transition from the coexistence to a mixing of adiabatic branches in the spectrum. It is shown that correlations between spin states allow for an interpolation between absorption bands for different optical asymmetries.Comment: 15 pages, revTeX, 8 figures, accepted for publication in Phys. Rev.

Self-directed passive-aggressive behaviour as an essential component of depression: findings from two cross-sectional observational studies

Background: The self-control model of depression suggests depressive symptoms to derive from distorted self-monitoring, dysfunctional self-evaluation and reduced self-reward as well as increased self-punishment. Building on this model a relationship between self-directed passive-aggressive behaviour, that is, harmful inactivity, and depression has been assumed. This association has been supported by a recent study in an inpatient sample. However, it remains unclear if patients with depressive disorders report more self-directed passive-aggressive behaviour than patients without depressive disorders and if self-directed passive aggression mediates the associations between distorted selfmonitoring and dysfunctional self-evaluation with depressive symptoms. Methods: Study 1 compared self-directed passive-aggressive behaviour levels between 220 psychotherapy outpatients with (n=140; 67.9% female; Mage=40.0) and without (n=80; 65.0% female; Mage=36.2) depressive disorders. Diagnoses were made based on the Structured Clinical Interview for DSM-IV. Study 2 examined self-directed passiveaggressive behaviour as a mediator of the relationship between distorted self-monitoring and dysfunctional selfevaluation and self-reported depressive symptoms in 200 undergraduate Psychology students. Results: Compared to outpatients without depressive disorders, outpatients with depressive disorder reported signifcantly more self-directed passive aggression (d=0.51). Furthermore, Study 2 verifed self-directed passiveaggressive behaviour as a partial mediator of the relationship between dysfunctional attitudes (abcs=.22, 95%-CI: .14, .31), attributional style (abcs=.20, 95%-CI: .13, .27), ruminative response style (abcs=.15, 95%-CI: .09, .21) and depressive symptoms. Conclusion: Self-directed passive-aggressive behaviour partially mediates the association between distorted selfmonitoring and dysfunctional self-evaluation with depressive symptoms. Future longitudinal studies need to examine a potential causal relationship that would form a base to include interventions targeting self-directed passive-aggressive behaviour in prevention and treatment of depression. Trial registration: Both studies were preregistered at the German Clinical Trials Register (DRKS00014005 and DRKS00019020)

Transport and dynamics on open quantum graphs

We study the classical limit of quantum mechanics on graphs by introducing a Wigner function for graphs. The classical dynamics is compared to the quantum dynamics obtained from the propagator. In particular we consider extended open graphs whose classical dynamics generate a diffusion process. The transport properties of the classical system are revealed in the scattering resonances and in the time evolution of the quantum system.Comment: 42 pages, 13 figures, submitted to PR

Classical dynamics on graphs

We consider the classical evolution of a particle on a graph by using a time-continuous Frobenius-Perron operator which generalizes previous propositions. In this way, the relaxation rates as well as the chaotic properties can be defined for the time-continuous classical dynamics on graphs. These properties are given as the zeros of some periodic-orbit zeta functions. We consider in detail the case of infinite periodic graphs where the particle undergoes a diffusion process. The infinite spatial extension is taken into account by Fourier transforms which decompose the observables and probability densities into sectors corresponding to different values of the wave number. The hydrodynamic modes of diffusion are studied by an eigenvalue problem of a Frobenius-Perron operator corresponding to a given sector. The diffusion coefficient is obtained from the hydrodynamic modes of diffusion and has the Green-Kubo form. Moreover, we study finite but large open graphs which converge to the infinite periodic graph when their size goes to infinity. The lifetime of the particle on the open graph is shown to correspond to the lifetime of a system which undergoes a diffusion process before it escapes.Comment: 42 pages and 8 figure

One-dimensional quantum chaos: Explicitly solvable cases

We present quantum graphs with remarkably regular spectral characteristics. We call them {\it regular quantum graphs}. Although regular quantum graphs are strongly chaotic in the classical limit, their quantum spectra are explicitly solvable in terms of periodic orbits. We present analytical solutions for the spectrum of regular quantum graphs in the form of explicit and exact periodic orbit expansions for each individual energy level.Comment: 9 pages and 4 figure

Pre-rehabilitation sense of coherence as a predictor of symptom change after rehabilitation

Sense of coherence (SOC) constitutes the key component of salutogenesis theory. It reflects individuals' confidence that their environment is comprehensible and manageable and that their lives are meaningful. Research demonstrates a strong cross-sectional relationship between SOC and mental health. However, little is known about SOC's temporal stability and its potential to predict changes in psychopathological symptom severity in different settings. The goal of the current study was to address this gap. The sample of the two-wave longitudinal study consists of 294 patients receiving inpatient psychotherapeutic (and psychopharmacological) treatment for various psychological disorders at a German psychosomatic rehabilitation clinic. SOC (Antonovsky, Social Science & Medicine, 1993, 36, 725-733) and outcome measures (i.e., general mental health problems, depression and anxiety symptoms) were assessed within two days of arrival and at the end of rehabilitation (week 5/6). SOC was significantly enhanced after treatment whereas psychopathological symptoms were significantly reduced. Regression analyses revealed that pre-treatment SOC was a significant negative predictor of post-treatment symptom severity for all outcome measures even after controlling for pre-treatment symptoms. The current findings provide first evidence that SOC is a significant unique predictor of symptom change. Future studies need to further investigate longitudinal associations between SOC and mental health outcomes in different settings

FlashCam: A fully digital camera for CTA telescopes

The future Cherenkov Telescope Array (CTA) will consist of several tens of telescopes of different mirror sizes. CTA will provide next generation sensitivity to very high energy photons from few tens of GeV to >100 TeV. Several focal plane instrumentation options are currently being evaluated inside the CTA consortium. In this paper, the current status of the FlashCam prototyping project is described. FlashCam is based on a fully digital camera readout concept and features a clean separation between photon detector plane and signal digitization/triggering electronics.Comment: In Proceedings of the 2012 Heidelberg Symposium on High Energy Gamma-Ray Astronomy. All CTA contributions at arXiv:1211.184