Comparison of the Gaia DR1 auxiliary quasar solution to recent ground based VLBI solutions for ICRF2 sources.

The present International Celestial Reference Frame (ICRF), the ICRF-3 is based on a catalogue of 4536 quasar positions obtained from Very Long Baseline Interferometry (VLBI) radio measurements. This radio frame is crucial for many applications, from measurements of Earth’s orientation in space to spacecraft navigation and measurements of sea-level rise. However, the deficit in ICRF source density in the South and lack of dedicated imaging campaigns in the South, to monitor structural changes, remain a big concern. These ICRF sources can exhibit spatially extended emission structures that can have a significant effect on astrometric VLBI measurements. The Celestial Reference Frame Deep South (CRDS) is a dedicated astrometric VLBI programme to observe Southern ICRF sources on a regular basis. In an effort to improve the situation in the South, these CRDS sessions have recently been optimized for VLBI imaging. In this thesis, I present VLBI images and source structure analysis results for southern ICRF sources observed in four of these CRDS sessions. For some of these sources, I present the very first high-resolution radio images. I also present results from source structure analysis and a corresponding assessment of astrometric quality, and I also present results from efforts to increase the ICRF source density in the South. / Mathematical Sciences / Ph. D. (Astronomy)

Die geodätischen Beobachtungsverfahren leisten auf verschiedene Weise Beiträge zur Erforschung des Systems Erde: Einerseits beobachten sie die rezenten Prozesse und ihre zeitlichen Variationen direkt, andererseit liefert sie die Grundlage für die konsistente Betrachtung aller Einflüsse in einem einheitlichen geometrischen und gravimetrischen Bezug. Das Projekt des Global Geodetic Observing System (GGOS) der Internationalen Assoziation für Geodäsie (IAG) soll die Voraussetzungen zur Vereinigung der verschiedenen geodätischen Beobachtungsverfahren, Modelle und Auswertemethoden mit dem Ziel schaffen, mit einem konsistenten Satz geodätischer Parameter ein hochgenaues Monitoring des Systems Erde zu ermöglichen. Die Realisierung geodätischer Bezugssysteme mit höchsten Genauigkeitsansprüchen ist in diesem Kontext eine zentrale Aufgabe des GGOS und Thema der vorliegenden Arbeit. In der derzeit üblichen Darstellung umfasst eine Realisierung des Terrestrischen Referenzsystems (TRS) Stationspositionen zu einer spezifischen Epoche und ihre linearen Änderungen mit der Zeit. In diesem Konzept führen alle nichtlinearen Stationsbewegungen zu residualen Abweichungen, die geowissenschaftlich interpretiert werden können. Der natürliche Ursprung eines globalen TRS, so auch des International Terrestrial Reference System (ITRS), liegt im Massezentrum des Systems Erde (CM). Mit Hilfe dynamischer Satellitenverfahren, wie GPS, lässt sich dieser Ursprung aus geodätischen Beobachtungen realisieren. In einem konsistenten Ausgleichungsansatz werden Satellitenbahnen, Stationspositionen und die in Kugelflächenfunktionen niedrigen Grades modellierte Auflastdeformation gemeinsam geschätzt. Die Grundlage der Realisierung des ITRS bilden in einem gemeinsamen Projekt der TU Dresden, der TU München und des GFZ Potsdam reprozessierte Beobachtungen eines über 200 Stationen umfassenden globalen GPS-Netzes des Beobachtungszeitraums 1994 bis 2007. Nach der Vorstellung der Grundprinzipien des GPS und seiner wesentlichen Fehlereinflüsse erfolgt die Beschreibung der Analyse der Beobachtungsdaten selbst. Sie umfasst die einheitliche Auswertung über den gesamten Zeitraum sowie Verbesserungen in der Modellierung der atmosphärischen Einflüsse und der Charakteristika der Sende- und Empfangsantennen sowie die Nutzung der Normalgleichungen zu Realisierung des ITRS. Der abgeleitete Terrestrische Referenzrahmen (TRF) wird Potsdam-Dresden-Reprocessing 2007 (PDR07) genannt. Zur Beurteilung der Genauigkeit und Zuverlässigkeit dieses TRF werden umfangreiche Analysen durchgeführt. So wird der PDR07 u.a. mit weiteren Realisierungen des ITRS, dem ITRF2000, dem ITRF2005 und den Realisierungen des International GNSS Service (IGS) IGb00 und IGS05, verglichen. Für eine Vielzahl geodynamischer Anwendungen werden GPS-Stationen in Messkampagnen beobachtet. Die hochgenaue Realisierung des ITRS in diesen regionalen GPS-Netzen ist für die geodynamische Interpretation der Ergebnisse zwingend erforderlich. Am Beispiel eines regionalen GPS-Netzes in der Antarktis wird untersucht, wie sich das ITRS in derartigen Netzen realisieren lässt und mit welcher Genauigkeit lineare Stationsbewegungen aus Kampagnenmessungen abgeleitet werden können. Im Anschluss werden die erhaltenen Bewegungsraten geodynamisch interpretiert: Aus den horizontalen Bewegungsraten wird die Bewegung der Antarktischen Kontinentalplatte im Konzept der Globaltektonik bestimmt und ihre innere Stabilität bewertet. Die vertikalen Stationsbewegungen werden genutzt, um Aussagen über rezente Krustendeformationen aufgrund glazialisostatischer Ausgleichsbewegungen und rezenter Massenvariationen des antarktischen Eises zu treffen. / The geodetic observation techniques contribute in several ways to the research of the system Earth: On the one hand they observe the recent processes and their variations in time directly, on the other hand they provide the basis for a consistent description of all effects in a consistent geometrical and gravimetrical reference. Within the project Global Geodetic Observing System (GGOS) of the International Association of Geodesy (IAG) the prerequisites for the combination of geodetic observation techniques, models and analysis strategies shall be created in order to enable a high accurate monitoring of the system Earth with consistent geodetic parameters. In this context the realization of geodetic reference systems with highest accuracy is a central task of the GGOS and subject of this thesis. At present, a common realization of the Terrestrial Reference System (TRS) consists of station positions according to a specific epoch and their linear changes with time. In this concept non-linear station motions yield to residual variations, which may be used for geoscientific interpretations. The natural origin of a global TRS, and this is also the case for the International Terrestrial Reference System (ITRS), is the center of mass of the system Earth (CM). This origin can be realized by observations of dynamic satellite techniques, such as GPS. In a consistent approach satellite orbits, stations positions and the lower degrees of harmonic surface mass load coefficients are estimated simultaneously. The ITRS is realized based on reprocessed observations of a global GPS network. In a joint effort TU Dresden, TU München and GFZ Potsdam analyzed the data of more than 200 stations of the observation time span 1994 to 2007. After an introduction to the basic principles of GPS and its major error sources the data analysis is described. This covers a homogeneous analysis over the entire period, improvements in atmosphere modeling and antenna phase center modeling as well as the usage of normal equations for the ITRS realization. The determined Terrestrial Reference Frame (TRF) is named Potsdam-Dresden-Reprocessing 2007 (PDR07). In order to assess the accuracy and stability of this TRF a variety of analyses is performed. For example, PDR07 is compared to other ITRS realizations, such as the ITRF2000, the ITRF2005 as well as the realizations of the International GNSS Service (IGS) IGb00 and IGS05. GPS campaign observations are often used to investigate geodynamic phenomena. The realization of the ITRS with highest accuracy in these regional GPS networks is essential for the geodynamic interpretation of the results. A regional GPS network in Antarctica is used to investigate the optimal way to realize the ITRS in such networks and the accuracy of linear station rates determined from campaign observations. Subsequently, the station rates are used for geodynamic interpretations: The horizontal station rates are used to determine the movement of the Antarctic Plate in the concept of global plate kinematics and to assess the inner stability of the Antarctic Plate. The vertical station rates are used to evaluate recent crustal deformations caused by glacial isostatic adjustment and recent mass changes of the Antarctic ice sheet.

Neste trabalho, propomos um conjunto de estratégias para enfrentar os obstáculos epistemológicos à aprendizagem da cinemática na Teoria da Relatividade Restrita. Tais estratégias são baseadas na proposta da noção de perfil conceitual de referencial (Ayala & Frezza, 2007) e visam promover uma interação cognitiva entre a Mecânica Newtoniana e Relativística. O perfil conceitual (Mortimer, 1995-2000) é um modelo para compreender a evolução conceitual em sala de aula. Para tais objetivos, foi desenvolvido um conjunto de ações em uma seqüência de aplicações de pré-testes e pós-testes com a finalidade de explicitar a concepção dos alunos sobre o aspecto a ser investigado e avaliar a evolução conceitual destes. A diferenciação entre as concepções dos alunos e aquelas cientificamente aceitas deu-se através da interpretação das concepções apresentadas, de discussões teóricas acerca do tema e da apresentação de animações construídas com o software Modellus. O público-alvo deste trabalho é formado por alunos de Licenciatura em Física, e o objetivo do mesmo é contribuir para a formação destes estudantes, futuros professores de Física. / In this work, we propose a set of strategies to face the epistemological obstacles to learning the kinematics in the Restricted Theory of Relativity. Such strategies are based on the proposal of the notion of conceptual profile of reference (Ayala & Frezza, 2007) and promote an interaction between cognitive Newtonian Mechanics and Relativistic Mechanics. The conceptual profile (Mortimer, 1995-2000) is a model for understanding the conceptual evolution of students in classroom. For these goals, we developed a set of actions in a sequence of applications of pre-tests and post-tests in order to explain the conception of students on the aspect to be investigated, and to assess your conceptual evolution. The differentiation between the students' conceptions and scientifically acceptable ones came through the interpretation of the concepts presented, theoretical discussions about the topic and the presentation of animations built with the software Modellus. The target of this work is formed by graduation students in Physics in order to contribute to your formation as future physics teachers.

Neste trabalho, propomos um conjunto de estratégias para enfrentar os obstáculos epistemológicos à aprendizagem da cinemática na Teoria da Relatividade Restrita. Tais estratégias são baseadas na proposta da noção de perfil conceitual de referencial (Ayala & Frezza, 2007) e visam promover uma interação cognitiva entre a Mecânica Newtoniana e Relativística. O perfil conceitual (Mortimer, 1995-2000) é um modelo para compreender a evolução conceitual em sala de aula. Para tais objetivos, foi desenvolvido um conjunto de ações em uma seqüência de aplicações de pré-testes e pós-testes com a finalidade de explicitar a concepção dos alunos sobre o aspecto a ser investigado e avaliar a evolução conceitual destes. A diferenciação entre as concepções dos alunos e aquelas cientificamente aceitas deu-se através da interpretação das concepções apresentadas, de discussões teóricas acerca do tema e da apresentação de animações construídas com o software Modellus. O público-alvo deste trabalho é formado por alunos de Licenciatura em Física, e o objetivo do mesmo é contribuir para a formação destes estudantes, futuros professores de Física. / In this work, we propose a set of strategies to face the epistemological obstacles to learning the kinematics in the Restricted Theory of Relativity. Such strategies are based on the proposal of the notion of conceptual profile of reference (Ayala & Frezza, 2007) and promote an interaction between cognitive Newtonian Mechanics and Relativistic Mechanics. The conceptual profile (Mortimer, 1995-2000) is a model for understanding the conceptual evolution of students in classroom. For these goals, we developed a set of actions in a sequence of applications of pre-tests and post-tests in order to explain the conception of students on the aspect to be investigated, and to assess your conceptual evolution. The differentiation between the students' conceptions and scientifically acceptable ones came through the interpretation of the concepts presented, theoretical discussions about the topic and the presentation of animations built with the software Modellus. The target of this work is formed by graduation students in Physics in order to contribute to your formation as future physics teachers.

Neste trabalho, propomos um conjunto de estratégias para enfrentar os obstáculos epistemológicos à aprendizagem da cinemática na Teoria da Relatividade Restrita. Tais estratégias são baseadas na proposta da noção de perfil conceitual de referencial (Ayala & Frezza, 2007) e visam promover uma interação cognitiva entre a Mecânica Newtoniana e Relativística. O perfil conceitual (Mortimer, 1995-2000) é um modelo para compreender a evolução conceitual em sala de aula. Para tais objetivos, foi desenvolvido um conjunto de ações em uma seqüência de aplicações de pré-testes e pós-testes com a finalidade de explicitar a concepção dos alunos sobre o aspecto a ser investigado e avaliar a evolução conceitual destes. A diferenciação entre as concepções dos alunos e aquelas cientificamente aceitas deu-se através da interpretação das concepções apresentadas, de discussões teóricas acerca do tema e da apresentação de animações construídas com o software Modellus. O público-alvo deste trabalho é formado por alunos de Licenciatura em Física, e o objetivo do mesmo é contribuir para a formação destes estudantes, futuros professores de Física. / In this work, we propose a set of strategies to face the epistemological obstacles to learning the kinematics in the Restricted Theory of Relativity. Such strategies are based on the proposal of the notion of conceptual profile of reference (Ayala & Frezza, 2007) and promote an interaction between cognitive Newtonian Mechanics and Relativistic Mechanics. The conceptual profile (Mortimer, 1995-2000) is a model for understanding the conceptual evolution of students in classroom. For these goals, we developed a set of actions in a sequence of applications of pre-tests and post-tests in order to explain the conception of students on the aspect to be investigated, and to assess your conceptual evolution. The differentiation between the students' conceptions and scientifically acceptable ones came through the interpretation of the concepts presented, theoretical discussions about the topic and the presentation of animations built with the software Modellus. The target of this work is formed by graduation students in Physics in order to contribute to your formation as future physics teachers.

Still increasing requirements are made on database systems, because users need to work with still more complex data. Because of the historical development of database systems, post-relational database systems are mainly used today. As follows from their name, post-relational database systems are built on relational database systems and expand them so that they are able to work with complex data. The vast majority of today's spatial database systems is based on post-relational databases. However, this work is trying to find a connection between object and spatial databases. The obtained knowledge is reflected in the implementation of the object database spatial extension.

Les éco-matériaux présentent un certain nombre de caractéristiques intéressantes comparativement à des solutions techniques ou architecturales classiques. Les critères de différenciation utilisés étaient jusqu’alors souvent liés à la préservation de l’environnement et de la santé. L’objectif de cette thèse est d’étudier les caractéristiques techniques, économiques et financières présentées par ces matériaux plus respectueux de l’environnement en regroupant des informations de référence sélectionnées au sein d’un référentiel proposé. La première partie de ce travail situe la thématique des éco-matériaux dans le contexte de la conception de bâtiments à qualité environnementale. Une deuxième partie précise la place des éco-matériaux au sein des systèmes de management de la qualité environnementale du bâti (SMQEB) internationaux et Européens. Le cahier des charges d’une méthode d’aide au choix d’éco-matériaux y est exposé. La troisième partie concerne la conception d’un outil d’aide à la prescription technique, économique et financière d’éco-matériaux. La dernière partie recentre sur un territoire d’étude la méthodologie élaborée et testée : la région Nord Pas de Calais. Un système constructif élaboré, un rampant de toiture, est utilisé comme base pour la comparaison d’un assemblage de solutions éco-construites et conventionnelles. Les critères techniques, économiques, financiers, environnementaux et de santé utilisés sont in fine traduits en ratio coûts / bénéfices / Eco-materials, have revealed a number of interesting characteristics compared with more traditional technical or architectural solutions. The criteria so far used to differentiate them were often related to the preservation of the environment or health. The main research objective has been to study the technical, economic and financial advantages of such more environmentally friendly materials by collecting selected referential information- assessment indicators and criteria- inside a proposed system of reference. The first part of my work has been devoted to identifying eco-materials in the broader context of the conception of high environmental quality buildings. The position of eco-materials in international and European Environmental Quality Management Systems for Buildings- SMQEB- has then been reviewed in a second part. The third part of this work has consisted in designing a technical, economic and financial prescription decision tool for eco –materials. In the final part, the main concern has been to implement this designed and tested methodology within the Nord Pas De Calais region. An elaborate construction system - a flat roof - has been selected to compare a set of eco-built solutions with more conventional ones. The technical, economic, financial, environmental and health criteria have in-fine been used in easily understood language: the cost/profit ratio

Diversity has, over the last few decades, become a burning issue on the agenda of most companies. Current diversity-related interventions are mainly based on behaviouristic and socio-cognitive approaches. In this research diversity was approached from the systems psychodynamic paradigm. The general aim was to gain an understanding of the diversity dynamics that manifests in an South African diversity experience. The literature review focussed on diversity in the workplace, on the group relations training model, and on the application of the group relations training model to diversity. Qualitative research was done by interviewing a sample of 15 delegates who attended the November 2000 Robben Island Diversity Experience. These unstructured interviews were used to obtain in-depth information about the participant's experience and the data was analysed hermeneutically. The emerging themes were `crossing the boundary, engage the new world, the ties that bind, being imprisoned, the struggle, the road to reconciliation, integration and healing, back to the future and the crucible'. It is recommended that South African organizations make more use of the systems psychodynamic approach to study the manifestations of diversity dynamics. The aim is not to replace the other approaches to diversity, but to add a perspective that can enhance awareness and sensitivity to the covert, unconscious and irrational forces that impact on diversity. / Industrial and Organisational Psycology / M. A.(Industrial and Organisational Psycology)

Diversity has, over the last few decades, become a burning issue on the agenda of most companies. Current diversity-related interventions are mainly based on behaviouristic and socio-cognitive approaches. In this research diversity was approached from the systems psychodynamic paradigm. The general aim was to gain an understanding of the diversity dynamics that manifests in an South African diversity experience. The literature review focussed on diversity in the workplace, on the group relations training model, and on the application of the group relations training model to diversity. Qualitative research was done by interviewing a sample of 15 delegates who attended the November 2000 Robben Island Diversity Experience. These unstructured interviews were used to obtain in-depth information about the participant's experience and the data was analysed hermeneutically. The emerging themes were `crossing the boundary, engage the new world, the ties that bind, being imprisoned, the struggle, the road to reconciliation, integration and healing, back to the future and the crucible'. It is recommended that South African organizations make more use of the systems psychodynamic approach to study the manifestations of diversity dynamics. The aim is not to replace the other approaches to diversity, but to add a perspective that can enhance awareness and sensitivity to the covert, unconscious and irrational forces that impact on diversity. / Industrial and Organisational Psycology / M. A.(Industrial and Organisational Psycology)