Imaging and photometry of U Antliae and AQ Andromedae using the Herschel space telescope

Die vorliegende Magisterarbeit beinhaltet die Beobachtungsauswertung und die Datenreduktion zweier Asymptotic Giant Branch (AGB) Sterne, U Ant und AQ And, welche mithilfe des Herschel Weltraumteleskops aufgezeichnet wurden. Die Ergebnisse dieser Datenreduktion werden mit der Modellierung in DUSTY verglichen, welche den Strahlungstransport in staubigen Umgebungen rund um Sterne simuliert. Mit den Ergebnissen ist es möglich, Rückschlüsse über die aktuelle und anschließende Entwicklung der Sterne zu ziehen. Im ersten Teil erhält der interessierte Leser eine Einleitung zu AGB-Sternen und ihren Eigenschaften. Dadurch erkennt der Leser, wie wichtig es ist, die Entwicklung dieser Spätstadien-Objekte zu studieren. Das Herschel Weltraumteleskop ist im Kapitel 2 beschrieben und besonderes Augenmerk ist auf das SPIRE Instrument gelegt. Ein eigenes Kapitel erläutert die technischen Eigenschaften sowie die Reduktion der Objekte für SPIRE. Das Reduktionskapitel präsentiert in großem Umfang die Datenstruktur, das Map-making sowie den Quellcode, um den Leser bei nachfolgenden Arbeiten zu unterstützen. Kapitel 3 “Science Objects” stellt die wichtigen Eigenschaften und Merkmale von beiden Objekten, U Ant und AQ And, dar. Zusätzlich gibt es eine Publikationsübersicht, die dem Leser eine Zusammenfassung der Publikationen mit Schwerpunkt “detached shell”- Beobachtung gibt. Das abschließende Kapitel befasst sich mit den Ergebnissen von der Beobachtung und der Modellierung von U Ant und AQ And. Die Ergebnisse der Beobachtung und die Aperturphotometrie befinden sich in einem separaten Kapitel. Schlussendlich sind die Resultate der Modellierung in einem Kapitel zusammengefasst und werden im Kapitel “Conclusion and interpretation” diskutiert.In this master thesis the observation evaluation and data reduction of two Asymptotic Giant Branch (AGB) stars, U Ant and AQ And, observed with the Herschel space telescope, is presented. The results from the data reduction will be compared with the modeling in DUSTY, which simulates the radiation transport in dusty environments around stars. With these results it is possible to draw conclusions about the current and subsequent evolution of the stars. The first part gives the interested reader an introduction to AGB-stars and their properties. So the reader will know, why it is important to study the evolution of these late-stage-objects. The Herschel space telescope is described in chapter 2, with special focus on the SPIRE instrument. A dedicated chapter outlines the technical functionality and data reduction part of the objects for SPIRE. The reduction process chapter presents in extended scope the data structure, the map-making as well as the final source code to support the reader’s subsequent workings. Chapter 3 “Science Objects” introduces the important properties and features of both science objects, U Ant and AQ And. In addition an overview of publications about (detached) shell-detection is given. The final chapter outlines the results of U Ant and AQ And from the observations and the modeling. The final maps from the observation as well as the aperture photometry can be found in a separate chapter. Furthermore the modeling outcomes are summed up in one chapter per object and are discussed in chapter “Conclusion and interpretation”

Determination of the corrosion progress of zirconium oxide containing refractories based on the natural intrinsic gamma radiation of the material

The determination of the corrosion progress of refractory blocks is interesting for the operation of glass furnace tanks under safety and economic aspects. The measuring principle, based on the very small natural radiation of impurities of the zirconium raw materials for refractory production, has been known since the beginning of the seventies of the last century and could now be developed through improvements of measuring technology and sensors. Smaller changes to a laboratory test setup from medical technology were made both in the hardware and the software, to enable measurements of the intrinsie radiation of fused-cast AZS refractory materials in hot and dusty environment on glass melting furnaces during operation. Α measuring schedule was developed and calibrating measurements were carried out with blocks of different zirconia content. First practical tests were made on cold glass furnaces. The final adaptation of the equipment was done with measurements on operating glass furnaces. The measurements of the corrosion progress and/or the residual thickness of refractory blocks based on the natural intrinsic gamma radiation could be done with the expected accuracy and can be used to support the operator of glass melting tanks

Beyond backscattering: Optical neuroimaging by BRAD

Optical coherence tomography (OCT) is a powerful technology for rapid volumetric imaging in biomedicine. The bright field imaging approach of conventional OCT systems is based on the detection of directly backscattered light, thereby waiving the wealth of information contained in the angular scattering distribution. Here we demonstrate that the unique features of few-mode fibers (FMF) enable simultaneous bright and dark field (BRAD) imaging for OCT. As backscattered light is picked up by the different modes of a FMF depending upon the angular scattering pattern, we obtain access to the directional scattering signatures of different tissues by decoupling illumination and detection paths. We exploit the distinct modal propagation properties of the FMF in concert with the long coherence lengths provided by modern wavelength-swept lasers to achieve multiplexing of the different modal responses into a combined OCT tomogram. We demonstrate BRAD sensing for distinguishing differently sized microparticles and showcase the performance of BRAD-OCT imaging with enhanced contrast for ex vivo tumorous tissue in glioblastoma and neuritic plaques in Alzheimer's disease