Now showing items 1-10 of 20
Existence and Regularity Results of a Ferroelectric Phase-Field Model
In this thesis, we investigate the existence and regularity results of a ferroelectric phase-field model, which is a state-of-the-art model arising in recent years from the engineering area for the ferroelectric study.
High-Speed 1.55 µm Quantum Dot Lasers with Electronically Coupled Quantum Well - Dot Active Regions
The expansion of long-distance data communication at a wavelength of 1.55 µm calls for larger data transfer rates. Consequently, an improvement of emission and modulation properties of lasers emitting in this wavelength region is of high interest. The utilization of so-called tunnel-injection (TI) structures in InP-based quantum dot (QD) lasers is promising to fulfill this task. The aim of this thesis was the realization and analysis of TI structures in the lattice matched InP material system and incorporation into ...
Gold Surface Nanostructuring with Ultrashort Laser Pulses - Study of Non-equilibrium Effects
Laser material interaction and structure formation in metals under controlled ultrashort laser pulse conditions are discussed in this work. A novel approach is presented describing the exact amount of energy deposited by a laser pulse in a gold surface, applicable under a variety of structuring conditions. The presented model is validated by a new introduced broad-band pump-probe reflectivity measurement method. A technique also applicable to investigate other phenomenas where 20 fs resolution combined with an octave ...
InP - based quantum dots for telecom wavelengths ranges
Long-distance quantum communication applications require sources of single photons, emitting at telecom wavelengths (around 1550 nm) with minimum attenu-ation losses of silica fiber. Semiconductor self-assembled InAs/InP-based quantum dots (QDs) are possible candidates to reach this spectral region. One of the challenges on the way is a QD asymmetry, which limits the fidelity of entangled photons. Therefore, morphological and optical properties of QDs should be improved in order to achieve the necessary quality and ...
BamB facilitates folding of outer membrane protein A (OmpA) via interactions of its β-propeller with the membrane surface and via a conformation change induced by phosphatidylglycerol
A sufficient folding and insertion of OMPs into the OM of Gram-negative bacteria requires the conserved β-barrel assembly machinery (BAM) complex. The present thesis concerns the structural properties and folding behavior of the lipoprotein BamB and describes its relevance in the synchronized mechanism of membrane insertion and folding of the β-barrel protein OmpA. Furthermore, specific binding sites in BamB involved in the interaction to the lipid membrane or the periplasmic domain of BamA (PD-BamA) were identified ...
Die Physiologie des Wirts-Parasitsystems pathogener Pilze des Eschentriebsterbens
In der vorliegenden Arbeit wurde versucht, die optimalen Wachstumsbedingungen des Pilzes H. fraxineus (Haupterreger des Eschentriebsterbens) zu ermitteln. Dafür wurden drei Wachstumsversuche (Nährmedium, pH-Wert und Temperatur) an 25 Pilzstämmen durchgeführt. • Die Ergebnisse des Nährmediumwachstumsversuches zeigten, dass Maismehl Agar Medium (MmA) die schnellste Kultivierung des Pilzes förderte und als das optimale Nährmedium gelten kann (im Vergleich mit den anderen sechs geprüften Nährmedien). • Der pH-Wert-Versuch ...
1.55 μm Quantum Dot Lasers for Telecommunication
The thesis at hand investigates the suitability of quantum dot (QD) material for use in long-distance coherent communication. The thesis was written in the frame of the SASER project MONOLOP that is aiming for a compact, monolithically integrated light source with a tunable wavelength covering the C+-band and narrow spectral linewidth below 500 kHz. The thesis reviews the theoretical background of quantum dot material based on the InP material system and distributed feedback (DFB) lasers with lateral gratings as ...
Phylogenetische und morphologische Untersuchungen der Gattung Palifer (Hymenochaetales, Basidiomycota)
The Hyphodontia s.l. genus Palifer has only been phylogenetically examined by one available ribosomal ITS and LSU sequence from GenBank. This Palifer verecundus sequence indicates a position of Palifer among Xylodon. During the studies for the presented master thesis 15 new ITS and 11 LSU sequences have been generated including Palifer gamundiae, P. hjortstamii, P. wrightii, and P. verecundus. The most successful combination of primer pairs was ITS5/ITS2 and ITS3/ALR0 for ITS amplification. The LSU region was amplified ...
Role of neurotransmitter GABA in the brain of the Madeira cockroach Rhyparobia maderae with focus on the circadian system
All living things are subject to biological rhythms. Circadian rhythms are generated by internal clocks which influence many biochemical and physiological processes, as well as various behaviors of an organism. These oscillators are synchronized by external "Zeitgeber" signals such as light-dark changes, temperature changes, as well as social contacts. Different studies identified the accessory medulla (AME), small neuropil at the ventromedian edge of the medulla, as the circadian pacemaker center of the cockroach ...