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Geodynamic evolution of the Pacific margin of West Antarctica based on apatite thermochronology
Get PDFThe West Antarctic continent formed during most of the Palaeozoic and Mesozoic era by accretion of crustal blocks to form the palaeo-Pacific margin of Gondwana. In the mid Cretaceous, Gondwana break-up was associated with a major change from convergence to extension along the palaeo-Pacific margin, which opened the West Antarctic rift system (WARS) and the Southern Pacific Ocean by separating Zealandia from West Antarctica. Further disintegration of Gondwana led to the separation of West Antarctica from South America by opening of the Drake Passage and the development of the Scotia Sea. Thus, Gondwana break-up and ensuing tectonic movements brought geographic isolation to Antarctica and potentially favoured the onset of glaciation. Extensive ice-cover of West Antarctica is itself one of the main challenges when trying to better constrain the geodynamic evolution since Gondwana break-up that remains poorly understood. This study focussed on western Marie Byrd Land (MBL) and the Thurston Island area which both form parts of the conjugate continental margins of Zealandia. Further investigation was carried out in the area of the South Orkney Islands and Elephant Island group (southern Scotia Sea). To comprehensively reconstruct the thermo-tectonic evolution of the upper 2-5 km of the crust, the main methods utilised in this study were apatite fission track (AFT) and apatite (U-Th-Sm)/He (AHe) thermochronology. Thermal history modelling of both AFT and AHe data was also carried out. For a better understanding of the geodynamic history, selected samples were analysed by means of U-Pb zircon geochronology and hornblende thermobarometry. The oldest thermochronological record was obtained from Carboniferous to Early Cretaceous (meta)igneous rocks of the Thurston Island area. Their AFT ages of 145-92 Ma and AHe ages of 112-43 Ma were integrated in thermal models and show episodes of cooling and reheating since the Late Palaeozoic. These episodes refer to exhumation and back-arc basin development between the Permian and the Early Cretaceous along the active paleo-Pacific margin. They also record exhumation during Early to mid Cretaceous basin inversion associated with magmatism and crustal thickening. Extension-related exhumation from 95 to 70 Ma occurred in response to the rifting between Zealandia and West Antarctica and from 75 to 60 Ma to activity along the Bellingshausen-Antarctic Plate boundary. Final exhumation since the Late Eocene was most-likely caused by activity of the WARS. Western MBL samples were mostly taken from the mid Cretaceous Byrd Coast Granite suite. These samples yield AFT and AHe ages of 105-68 Ma and thermal models are compatible with rapid tectonic exhumation from 105 to 95 Ma during WARS-extension. This was followed by a phase of exhumation between 95 and 80 Ma in response to rifting and breakup between Zealandia and West Antarctic. The southern-most samples record exhumation from 80-60 Ma due to faulting in the Ross Sea region. Slow cooling during the Late Cretaceous-Early Cenozoic corresponds with the formation of the West Antarctic erosion surface and relative tectonic quiescence. Late Cenozoic WARS rifting, MBL-dome uplift, and onset of glaciation appears to have had little effect on erosion processes in western MBL. Pre-mid Cretaceous sedimentary and metamorphic samples of the South Orkney Islands yield AFT ages of 77-54 Ma and AHe ages of 61-5 Ma. These ages, interpreted with the help of thermal history models record Late Cretaceous-Early Cenozoic margin-wide uplift and erosion of high-standing topography. Relatively slow exhumation since the Late Eocene was associated with the opening of the Powell Basin. Metamorphic and igneous samples from the Elephant Island group reveal AFT and AHe ages of 30-23 Ma and 6-2 Ma. A diorite and a granodiorite samples yield U-Pb zircon ages of 28 and 10 Ma. The geo- and thermochronological ages and the identified cooling episodes probably refer to two periods of major plate reorganisations in the southern Scotia Sea. First, intrusion and exhumation during the Oligocene occurred probably in response to inception of the Shackleton Fracture Zone and the West Scotia Ridge. Second, rapid tectonic exhumation in the Late Miocene/Pliocene occurred due to cessation of two spreading ridges coupled with the opening of the Bransfield Strait
Japanese Brazilians in Hamamatsu City : An Ethnographic Study on the Second Generation
Get PDFAt the end of the 1980s, the Brazilians of Japanese descent were officially allowed to enter Japan as unskilled workers, solving the country's labor shortages. Since then, as a new ethnic minority group, they are facing many issues in this host society. Despite the vast research on this ethnic return migration, known as the Dekasegi Movement, little is known about its young generation. Therefore, the purpose of this ethnographic study is the analysis of the current situation of the Japanese Brazilians in Hamamatsu City with a focus on their second generation. Fieldwork was conducted in order to portray this minority group from different perspectives. The empirical findings demonstrate the way these young people have been perceived and presented in this transnational context, confirming their stigmatization as the children of immigrants. Moreover, such a negative perception has influenced the way they see themselves, thereby limiting their perspectives, and creating many uncertainties and challenges for the future. In conclusion, this study suggests further research on the meaning of Japaneseness , which still reinforces narratives of pure blood and nationality, dominating public consciousness and influencing not only views and attitudes towards foreigners, but also the formulation, analysis, and review of migration policies in Japan
Improving an optimal estimation algorithm for surface and atmospheric parameter retrieval using passive microwave data in the Arctic
Get PDFIn this study we present improvements on an integrated retrieval method for atmospheric and surface parameters in the Arctic. The instrument used is the Advanced Microwave Scanning Radiometer - Earth Observing System (EOS) (AMSR-E) radiometer on board NASAa s Aqua satellite. The core of the method is a forward model which can ingest bulk data for seven geophysical parameters to reproduce the brightness temperatures observed by a passive microwave radiometer. The method inverts the forward model and produces ensembles of the seven parameters: wind speed, integrated water vapor, liquid water path, sea and ice temperature, sea ice concentration and multi-year ice fraction. The method is constrained using numerical weather prediction data in order to retrieve a set of geophysical parameters that best fit the measurements. An iterative method minimizes the cost function and finds the optimal ensemble of the seven parameters that best match the observed brightness temperatures
Balancing between Here and There : A Relational Perspective on Migrants Lives between Place Attachment and Mobility
Get PDFIn this paper I present the central results of a research project on the nexus of place attachment and mobility of highly qualified international migrants. Based on empirical data obtained from narrative interviews with highly qualified international migrants and ethnographic interviews with informants from the scene, I show that repeatedly migrating people develop forms of place attachment at their temporary places of residency which can be understood as a mode of stabilising and homogenising hybrid identities; here, constituting spaces and integrating objects as constitutive components in their practices of staying and moving are key. Today, we observe a, in qualitative terms significant, group of highly qualified people who repeatedly cross national borders in their professional lives. This has societal consequences, grasped for example by Zygmunt Bauman (e.g. 1996, 1997, 1998, 2003, 2005) with his description of so-called tourists and vagabonds as key social figures. Building on this conceptually helpful dichotomy of voluntary versus forced migration, I focus on those tourists and ask how they balance between transnational mobility and localized place attachment. My data show that the interviewees develop specific social and spatial practices to establish local ties and an identity which is stable enough to withstand the repeated changes of relocation and, connected with this, repeated processes of uprooting and regrounding (Ahmed et al. 2003). Here, objects play a key role for both mobility and place attachment, suggesting a relational perspective (Callon 1986, Latour 2007) on the nexus of place attachment and mobility
Kunst und Leben: Kindheitserinnerungen eines Filmemachers
Get PDFIn dem Film Jacquot de Nantes (1991) widmet sich die Regisseurin Agnes Varda der Kindheit und Jugend ihres Mannes, des Musicalregisseurs Jacques Demy. Die nicht-lineare Erzählform verwebt drei Stränge miteinander - Episoden der Kindheit, Dokumente der Gegenwart des alten Jacques Demy und Zitate seiner Filme - und reflektiert damit den Prozess des Erinnerns, aber auch der ästhetischen Filmbildung. Der Artikel analysiert am Beispiel von Jacquot de Nantes Kindheit als eine Kategorie der Erinnerung, in der sich Gegenwart und Vergangenheit überlagern, Kindheit und Erwachsensein gegenseitig bedingen: Wie wird die Kindheit hier als biografische Erfahrung und als Prozess des Erinnerns dargestellt? Was sagt uns der Film über ästhetische Bildung? Wie überlagern sich die Blicke des Kindes (das erlebt) und des Erwachsenen (der erinnert)? Dabei wird auch herausgearbeitet, wie der Film in seiner formalen Gestaltung die gegenläufigen Prozesse der Bildung und der Erinnerung als Durchdringung körperlich-sinnlicher und semiotischer-intertextueller Aspekte veranschaulicht
Multiple Testing under Copula Dependency Structures
Get PDFThe key to multiple testing is to respect the dependencies between the marginal hypotheses tests. Any dependency structure can be modeled by so-called copula functions. This makes copulas an interesting tool in multiple testing. In particular, it is possible to explicitly utilize the dependency structure of the data. This leads to the sub-class of copula-based multiple tests. One family of non-parametric copula estimators is constituted by Bernstein copulas. We extend previous statistical results regarding bivariate Bernstein copulas and study their impact on multiple tests. A related topic is the estimation of the proportion of true null hypotheses pi 0. It is a well known result in multiple hypothesis testing that this proportion is not identified under general dependencies. However, it is possible to estimate pi 0 if structural information about the dependency structure among the p-values is available
Auslegung und Konstruktion einer Schleudergussanlage zur Herstellung von Paraffintreibsätzen für die studentische Rakete ZEpHyR 2
Get PDFAm ZARM an der Universität Bremen wird derzeit eine Hybridrakete, die ZEpHyR 2, entwickelt, die mit Flüssigsauerstoff und Paraffin betrieben werden soll. Dafür müssen Paraffintreibsätze hergestellt werden. Die vorhandene Schleudergussanlage zur Herstellung von Paraffintreibsätzen ist mittlerweile veraltet, zu klein und sehr wartungsintensiv. Deswegen soll in der vorliegenden Bachelorarbeit eine neue Schleudergussanlage ausgelegt und konstruiert werden. Das Ziel ist, dass die neue Anlage möglichst keine Defizite der vorhandenen Anlage aufweist und Paraffintreibsätze ohne Lufteinschlüsse und mit einem gleichmäßigen Port für die ZEpHyR 2 herstellt, damit das Abbrennen des Paraffintreibsatzes möglichst gleichmäßig abläuft. Hierfür wurde die vorhandene Anlage genau analysiert und es wurden anhand der gründlichen Analyse und Auslegung mehrere Konzepte erarbeitet sowie die letzten beiden miteinander verglichen. Im Endkonzept wird die neue Schleudergussanlage vorgestellt
Die Netzwerk-Balanced Scorecard als Instrument zur Erfolgsmessung von kooperativer Destinationsentwicklung
Get PDFHacking Cultural Heritage : the Hackathon as a Method for Heritage Interpretation
Get PDFHackathons were originated from both the evolution of and revolution caused by personal computers. Initially, they have been implemented as a collaborative method for solving computer-related problems or conceptualizing new possibilities based on specific infrastructures. Only later on, when Cultural Institutions had undergone intensive digitization, Hackathons started to be part of their repertoire. Because of the special nature of Cultural Institutions, Hackathons for Cultural Heritage cannot be understood in the same way as their counterparts happening in a purely engineering domain. Problem solving and conceptualization through collaborative programming are entangled with the significance of the content matter they intend to deal with: the institutionsa collections. Based on these considerations, this thesis aims at explaining the underlying principles, interactions, and infrastructures of the Hackathon as a method for Heritage Interpretation. Moreover, the thesis also proposes a Fast-speed IT Platform, which was designed within the context of the Two-speed IT infrastructure, where a foundational, stable, and slow infrastructure is complemented by an additional creative, experimental, and agile infrastructure, which is capable of promptly responding to the needs of communities. The platform is an effort to implement strategies for interpreting, recontextualizing, and telling stories with Digital Collections. In addition, the platform aims at mitigating problems concerning technical knowledge that is usually required for taking advantage of the affordances of Digital Collections as a creative material
