"Der guote sundaere" Gregorius als christlicher Ödipus : Mythenrezeption in Thomas Manns Roman "Der Erwählte"

Als Hartmann von Aue vor gut 800 Jahren seine Version der Gregoriuslegende niederschrieb, mag ihm der Ödipusmythos bekannt gewesen sein, aus der Perspektive eines mittelalterlichen Gelehrten war dieser jedoch ein Überbleibsel aus einer vorchristlichen und damit gottesfernen Zeit und eher über den Umweg der christlichen Allegorese interessant. Wahrscheinlicher ist es hingegen, dass für ihn die Legende vom heiligen Papst eine historisch wahre, die Allmacht Gottes unter Beweis stellende Geschichte war. Thomas Mann versteht Hartmanns Gregorius hingegen in Folge seiner Beschäftigung mit den mythologischen Ursprüngen der europäischen Kultur als Variante des Ödipusdramas Sophokles’ und versucht in dem Erwählten die antiken Quellen zum einen auf einer literaturhistorischen Ebene freizulegen, zum anderen jedoch auch im Rahmen der psychoanalytischen Theorie zu interpretieren. Im Folgenden wird diesem Interpretationsansatz anhand der Differenzen der Textfassungen nachgegangen, um die Frage zu erörtern, welche Elemente des Ödipusmythos Thomas Mann aus der Gregoriuslegende herausgearbeitet hat. ..

Optically and electrically controllable adatom spin-orbital dynamics in transition metal dichalcogenides

We analyze the interplay of spin-valley coupling, orbital physics and magnetic anisotropy taking place at single magnetic atoms adsorbed on semiconducting transition-metal dichalcogenides, MX$_2$ (M = Mo, W; X = S, Se). Orbital selection rules turn out to govern the kinetic exchange coupling between the adatom and charge carriers in the MX$_2$ and lead to highly orbitally dependent spin-flip scattering rates, as we illustrate for the example of transition metal adatoms with $d^9$ configuration. Our ab initio calculations suggest that $d^9$ configurations are realizable by single Co, Rh, or Ir adatoms on MoS$_2$, which additionally exhibit a sizable magnetic anisotropy. We find that the interaction of the adatom with carriers in the MX$_2$ allows to tune its behavior from a quantum regime with full Kondo screening to a regime of "Ising spintronics" where its spin-orbital moment acts as classical bit, which can be erased and written electronically and optically.Comment: 6 pages, 4 figure

Coulomb interaction and phonons in doped semiconducting and metallic two-dimensional materials

Two-dimensional (2D) materials present a rapidly developing field of research with sometimes highly unusual and uniquely two-dimensional physics. Starting with graphene, many recent studies have investigated 2D materials, with results for properties encompassing such different topics as Dirac electrons, charge ordering, and superconductivity. To get closer to a predictive theory of the phases of 2D materials, this thesis systematically tackles the previously unclear problem of the Coulomb interaction and its influence on the electronic and many-body properties, with the focus on transition metal dichalcogenides (TMDCs). While this influence can be quite strong due to the low dimensionality and the corresponding reduced screening, there is so far no comprehensive understanding of the Coulomb interaction in 2D, its effects, and the possibilities for engineering it. Furthermore, the interplay between electron-electron interaction, electron-phonon interaction, and screening is far from being fully understood. The goal of this thesis is to improve on this by providing a description of the Coulomb interaction for the example of the TMDCs as well as to develop a material-systematic database on the basis of ab-initio calculations for electrons and phonons. We use Density Functional Theory to describe the electronic structure, Density Functional Perturbation Theory for the phonons and the electron-phonon interaction, and the Random Phase Approximation to obtain Coulomb matrix elements. In addition to both semiconducting and metallic TMDCs, we look at functionalized graphene C8H2. The first step is a quantification of the Coulomb interaction and the screening in the TMDCs along with calculations for the plasmonic spectra, which turn out to be highly susceptible to environment and doping. Secondly, we discuss the influence of the interaction on different many-body instabilities and find a small suppression of superconducting order in semiconducting TMDCs, depending again on doping and the dielectric environment, while the magnetic order in metallic TMDCs is enhanced. If we further include the phonons, we see that superconductivity is predicted to be a global phenomenon in the doped semiconducting TMDCs and C8H2, and that charge density waves at different wave vectors are supposedly occurring in all TMDCs

Expression des 5-HT1A-Rezeptors als Parameter für die retrospektive Belastungseinschätzung in Nagermodellen

Experimentelle und klinische Daten suggerieren einen Einfluss von serotonerger Neurotransmission auf die Stressantwort sowie die Anfallsschwelle bei Patienten mit Epilepsie und Epilepsie-assoziierten psychiatrischen Komorbiditäten. Möglicherweise eignet sich die 5-HT1A-Rezeptorexpression als Biomarker für die Belastungseinschätzung in Tiermodellen. In μPET-Studien unserer Arbeitsgruppe konnte in Stress- und Epilepsiemodellen ein erhöhtes Bindungspotential des 5-HT1A-Rezeptor-Liganden [18F]MPPF bei Ratten nachgewiesen werden. Ursächlich dafür kann die Erhöhung der Rezeptorexpression oder eine Reduktion der extrazellulären Serotoninkonzentration, und dadurch Reduktion der kompetitiven Hemmung durch den endogenen Liganden, sein. Auf Basis dieser Ergebnisse sollte untersucht werden, ob die potentielle Nutzung der 5-HT1A-Rezeptorexpression als Biomarker zur Belastungseinschätzung in Nagermodellen bestätigt werden kann. Unter Anwendung stereologischer Prinzipien wurde die 5-HT1A-Rezeptorexpression in immunhistochemisch gefärbten Gehirngewebeschnitten von Ratten aus einem Restraint-Stressmodell sowie zwei Post-Status-Epilepticus-Modellen quantifiziert. Die Auswahl der untersuchten Gehirnregionen erfolgte auf Grundlage der μPET-Studienergebnisse. Es wurden das Septum und verschiedene Subregionen des Hippocampus untersucht. Die Quantifizierung der 5-HT1A-Rezeptorexpression zeigte eine reduzierte optische Dichte in der CA3-Region im elektrischen Post-Status-Epilepticus-Modell und in der CA1-Region im Restraint-Stressmodell. In dem chemischen Post-Status-Epilepticus-Modell zeigte die Analyse keine Unterschiede zwischen den experimentellen Gruppen. Modellspezifisch wies eine Korrelationsanalyse auf eine Verbindung zwischen der 5-HT1A-Rezeptorexpression und einigen der μPET-Daten sowie Anfalls- und Verhaltensparametern hin. Zusammenfassend sprechen die vorliegenden Ergebnisse gegen eine ausgeprägte Veränderung der 5-HT1A-Rezeptorexpression in den untersuchten Gehirnregionen. Die erhobenen Daten legen nahe, dass die zuvor gezeigten Veränderungen der Bindung des μPET-Tracers auf eine Reduktion des endogenen Serotonins zurückzuführen ist. DieExperimental and clinical data suggest an impact of serotonergic neurotransmission on stress response and seizure susceptibility in patients with epilepsy, as well as on epilepsy- associated comorbidities. 5-HT1A receptor expression is a potential biomarker candidate for severity assessment in animal models. In μPET studies, previously completed by our group, an increased binding potential of the 5-HT1A receptor ligand [18F]MPPF was shown in stress and epilepsy models in rats. The reason for an increased binding potential could be an enhanced 5-HT1A receptor expression or reduced endogenous serotonin levels and therefore a reduction of the competitive inhibition by the endogenous ligand. Based on these results, the potential use of the 5-HT1A receptor expression as a biomarker candidate for severity assessment in animal models was evaluated. Applying stereologic principles, the 5-HT1A receptor expression was quantified in immunohistochemically stained rat brain sections. These were derived from two post-status epilepticus models and one restraint stress model. Selection of the regions of interest was based on μPET results. Septum and subregions of the hippocampus were analysed. Immunohistochemically based quantification showed a reduced optical density in the hippocampal CA3 subregion in the electrical post-status epilepticus model and in the hippocampal CA1 subregion in the restraint stress model. In the chemical post-SE model, expression rates were comparable in all brain regions of interest. Model specific correlations indicated a potential link of 5-HT1A receptor expression with μPET data, as well as ictogenesis, seizure and behavioural parameters. In conclusion, the results obtained in this study do not indicate widespread alterations of the receptor expression in the examined brain regions. In regard of previously assessed μPET data, the results indicate reduced serotonin levels rather than enhanced receptor density as an explanation for changes in [18F]MPPF binding. The correlation analysis points to a potential connection between 5-HT1A receptor expression and ictogenesis, seizure termination and behavioural patterns. Since these findings are model-specific, the generalizability should be further evaluated in future studies using other models and species

Coulomb interaction and phonons in doped semiconducting and metallic two-dimensional materials

Two-dimensional (2D) materials present a rapidly developing field of research with sometimes highly unusual and uniquely two-dimensional physics. Starting with graphene, many recent studies have investigated 2D materials, with results for properties encompassing such different topics as Dirac electrons, charge ordering, and superconductivity. To get closer to a predictive theory of the phases of 2D materials, this thesis systematically tackles the previously unclear problem of the Coulomb interaction and its influence on the electronic and many-body properties, with the focus on transition metal dichalcogenides (TMDCs). While this influence can be quite strong due to the low dimensionality and the corresponding reduced screening, there is so far no comprehensive understanding of the Coulomb interaction in 2D, its effects, and the possibilities for engineering it. Furthermore, the interplay between electron-electron interaction, electron-phonon interaction, and screening is far from being fully understood. The goal of this thesis is to improve on this by providing a description of the Coulomb interaction for the example of the TMDCs as well as to develop a material-systematic database on the basis of ab-initio calculations for electrons and phonons. We use Density Functional Theory to describe the electronic structure, Density Functional Perturbation Theory for the phonons and the electron-phonon interaction, and the Random Phase Approximation to obtain Coulomb matrix elements. In addition to both semiconducting and metallic TMDCs, we look at functionalized graphene C8H2. The first step is a quantification of the Coulomb interaction and the screening in the TMDCs along with calculations for the plasmonic spectra, which turn out to be highly susceptible to environment and doping. Secondly, we discuss the influence of the interaction on different many-body instabilities and find a small suppression of superconducting order in semiconducting TMDCs, depending again on doping and the dielectric environment, while the magnetic order in metallic TMDCs is enhanced. If we further include the phonons, we see that superconductivity is predicted to be a global phenomenon in the doped semiconducting TMDCs and C8H2, and that charge density waves at different wave vectors are supposedly occurring in all TMDCs