This modelling study aims to gain an improved understanding of the processes that determine the water vapour budget in the stratosphere by means of the investigation of water isotope ratios. At first, a separate hydrological cycle has been introduced into the chemistry-climate model EMAC, including the water isotopologues HDO and H218O and their physical fractionation processes. Additionally, an explicit computation of the contribution of methane oxidation to HDO has been incorporated. EMAC simu...
Jun 03, 20140
In dieser Arbeit untersuche ich den Einfluss massiver Quantenfelder auf einen reinen de Sitter Hintergrund. Nach einer kurzen Zusammenfassung der neuesten Entwicklungen zu diesem Thema gebe ich eine Einführung in die klassische Geometrie von de Sitter Räumen. Darin behandle ich die physikalischen Eigenschaften und die verschiedenen Koordinatensysteme, die unterschiedliche Teile des de Sitter Raumes bedecken. Im anschließenden Kapitel wiederhole ich die Quantenfeldtheorie freier Skalarfelder au...
Jun 03, 20140
May 28, 20140
Der Beitrag der Luftfahrt am gesamten anthropogenen Strahlungsantrieb beträgt 3-8 %. Mit steigendem Luftverkehrsaufkommen um etwa 5 % jährlich wächst dieser Beitrag stetig an. Kondensstreifenzirren machen den größten Anteil an der Klimawirkung des Luftverkehrs aus. Die Ergebnisse der bisherigen Studien sind aber noch mit großen Unsicherheiten versehen. Mit dem Ziel einer realistischeren Darstellung von Kondensstreifenzirren und genaueren Validierungsmöglichkeiten der Kondensstreifenzirren-Parame...
May 15, 20140
In kühlen Sternen wie der Sonne wird die nuklear erzeugte Energie aus dem Inneren an die Oberfläche transportiert. Diese kann dann in den freien Weltraum entfliehen, und so können wir das Sternenlicht letztlich beobachten. Die theoretische Modellierung des photosphärischen Übergangsbereiches – vom konvektiven zum radiativen Energietransport – ist aufgrund der inhärenten dreidimensionalen (3D) Natur der Konvektion und der komplexen, nicht-linearen und nicht-lokalen Interaktionen des Strahlungsfel...
May 14, 20140
May 09, 20140
The chemical compositions of the stars and gas in galaxies play a significant role in all their key evolutionary processes, from gas cooling, through star formation, to the production of new heavy elements that are released back into the gas as stars die in supernova explosions. A theoretical explanation of the production of elements heavier than helium (known simply as `metals' in astrophysics) in stars and its distribution throughout galaxies has been developing since the first postulation of ...
May 07, 20140
Die Untersuchung der Moduli Räumen von N = (2,2) Superkonformen Feldtheorien und der allgemeineren N = (2,2) Supersymmetrischen Quanten Feldtheorien ist ein langjähriges und vielseitiges Forschungsgebiet. Diese Dissertation konzentriert sich auf gewisse allgemeine Aspekte des erwähnten Studiums, und stellt Entwicklungen von allgemeinen Methoden im Rahmen der Topologischen String Theorie dar. Die vorliegende Arbeit besteht aus zwei Teilen. Der erste Teil befasst sich mit Aspekten der geschlossene...
Apr 30, 20140
Apr 28, 20140
Micromegas are high-rate capable, high-resolution micro-pattern gaseous detectors. Square meter sized resistive strip Micromegas are foreseen as replacement of the currently used precision tracking detectors in the Small Wheel, which is part of the forward region of the ATLAS muon spectrometer. The replacement is necessary to ensure tracking and triggering performance of the muon spectrometer after the luminosity increase of the Large Hadron Collider beyond its design value of $10^{34}$\,cm$^{-2...
Apr 28, 20140
Germanium detectors are a choice technology in fundamental research. They are suitable for the search for rare events due to their high sensitivity and excellent energy resolution. As an example, the GERDA (GERmanium Detector Array) experiment searching for neutrinoless double beta decay is described. The observation of this decay would resolve the fundamental question whether the neutrino is its own antiparticle. Especially adapted detector technologies and low background rates needed to detect...
Apr 14, 20140
Apr 11, 20140
This thesis unifies several studies, which all are dedicated to the subject of statistical data analysis in radio astronomy and radio astrophysics. Radio astronomy, like astronomy as a whole, has undergone a remarkable development in the past twenty years in introducing new instruments and technologies. New telescopes like the upgraded VLA, LOFAR, or the SKA and its pathfinder missions offer unprecedented sensitivities, previously uncharted frequency domains and unmatched survey capabilities. Ma...
Apr 10, 20140
Apr 09, 20140
Feb 27, 20140
Two analyses searching for squarks and gluinos which decay into final states with multiple jets, an isolated electron or muon and a large missing transverse energy are presented. Both rely on data taken by the ATLAS detector in pp collisions at a center-of-mass energy of 8 TeV at the LHC during 2012. The first analysis uses a subset of 5.8 fb-1 of this dataset, the other analysis uses the full statistics of 20.3 fb-1. Both analysis share the same methods regarding the triggers and the background...
Feb 26, 20140
Feb 26, 20140
Why do we exist? CP violation is an integral part of this question as its understanding is crucial to explain the matter-antimatter asymmetry observed in our universe. Several experiments were designed and carried out to precisely measure CP violation, especially in the B meson system where large asymmetries where predicted and found. With Belle II and LHCb, two new experiments are going to improve the existing measurements. Belle II will be based on the very successful Belle experiment at the K...
Feb 25, 20140
In dieser Arbeit wird ein schnelles Strahlungsmodell im sichtbaren Spektralbereich erstellt. Ausgehend vom von einem meteorologischen Modell berechneten Zustand der Atmosphäre ergibt dieses Strahlungsmodell die Strahldichte am oberen Rand der Atmosph äre, die ein Satellit messen würde, wenn die Atmosphäre tatsächlich so aussehen würde (synthetisches Satellitenbild). Der Vergleich mit einem tatsächlichen Satellitenbild gibt Hinweise über mögliche Fehler des meteorologischen Modells. Mehrere Forsc...
Feb 24, 20140
We present a study of the galaxy populations in massive galaxy clusters selected by their Sunyaev–Zel’dovich Effect (SZE) signatures. Selection via the SZE is approximately mass- limited where the mass limit varies only slightly with redshift, making it an ideal selection method for studying the evolution of the galaxy content of clusters. We begin by introducing the SZE, the South Pole Telescope (SPT), and the larger research project in which this Thesis is embedded. We then present the core ga...
Feb 24, 20140
One of the most fundamental correlations between the properties of galaxies in the local Universe is the so-called morphology-density relation (Dressler 1980). A plethora of studies utilizing multi-wavelength tracers of activity have shown that late type star forming galaxies favour low density regions in the local Universe (e.g. G´omez et al. 2003). In particular, the cores of massive galaxy clusters are galaxy graveyards full of massive spheroids that are dominated by old stellar populations. ...
Feb 24, 20140
Feb 21, 20140
The work presented here focuses on the investigation and further development of simple mass estimators for early-type galaxies which are suitable for large optical galaxy surveys with poor and/or noisy data. We consider simple and robust methods that provide an anisotropy-independent estimate of the galaxy mass relying on the stellar surface brightness and projected velocity dispersion profiles. Under reasonable assumptions a fundamental mass-anisotropy degeneracy can be circumvented without inv...
Feb 21, 20140
Feb 12, 20140
The search for exo-planets is currently one of the most exiting and active topics in astronomy. Small and rocky planets are particularly the subject of intense research, since if they are suitably located from their host star, they may be warm and potentially habitable worlds. On the other hand, the discovery of giant planets in short-period orbits provides important constraints on models that describe planet formation and orbital migration theories. Several projects are dedicated to discover an...
Feb 10, 20140
Feb 07, 20140
Das Gebiet der Nichtgleichgewichtsdynamik stark korrelierter Quantensysteme beinhaltet eine Vielzahl interessanter Fragestellungen, erweist sich dabei allerdings oftmals als schwer zugänglich für gängige numerische und analytische mathematische Methoden. In den letzten Jahren hat sich durch die experimentelle Realisierung gut kontrollierbarer quantenmechanischer Systeme die Möglichkeit eröffnet, Experimente als Quantensimulatoren für das Verhalten komplexer Vielteilchensysteme zu benutzen. Ultra...
Jan 30, 20140
The majority of stars in the universe has formed in disc galaxies with masses similar to that of the Milky Way. Ab-initio cosmological hydrodynamical simulations of the formation and evolution of galaxies in a Lambda Cold Dark Matter universe have long suffered from serious problems in correctly modelling the star-formation history and structure of disc galaxies. We first use idealized semi-cosmological simulations to gain a better understanding of processes leading to problems in disc formation...
Jan 29, 20140
Semiconducting single-walled carbon nanotubes (CNTs) exhibit a chirality depended band structure of a one-dimensional lattice. Due to the radiative recombination of excitons CNTs emit photoluminescence in the near and mid infrared ranges depending on the tube diameter. Excitons are subject to diffusion along the tube before radiative recombination. Thereby they probe sites that give rise to spin-flips or non-radiative decay, or, at cryogenic temperatures, they localize in zero-dimensional quantu...
Jan 27, 20140
Jan 27, 20140
