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Die vorliegende Arbeit befasst sich mit der Untersuchung von Wanderungsüberlegungen der Einwohner der Stadt Visaginas vor dem Hintergrund steigender ökonomischer Unsicherheit, bedingt durch die bevorstehende Schließung des Atomkraftwerkes 'Ignalina'. Visaginas befindet sich im Nordosten Litauens, in einer der strukturschwächsten Regionen des Landes. Von Mitte der 70er bis Ende der 80er Jahre entstand die Stadt als Wohnstätte für die Arbeiter des sich zu dieser Zeit ebenfalls im Bau befindlichen Atomkraftwerkes 'Ignalina' sowie für deren Angehörige. Noch heute ist die Stadt wirtschaftlich vom Kraftwerk abhängig: Nicht nur ist das staatliche Unternehmen der größte Arbeitgeber für die ca. 30.000 Einwohner, sondern darüber hinaus stellt auch die Mehrzahl der unabhängigen Firmen ihre Leistungen und Produktion in dessen Dienst. Auf Druck der Europäischen Union, welche bereits Ende der 90er Jahre aus sicherheitstechnischen Gründen die Schließung des Atomkraftwerkes forderte, beschloss die Regierung Litauens, das Atomkraftwerk stillzulegen. Am 1. Januar 2005 wird der Betrieb des ersten Reaktors eingestellt. Die endgültige Abschaltung ist bis zum Januar 2009 vorgesehen. Auf diese Weise wird der Stadt Visaginas, und damit verbunden vielen ihrer Einwohner, die wirtschaftliche Existenzgrundlage entzogen. Bedingt durch den Wegfall ihres Arbeitsplatzes wird ein Großteil der Einwohner gezwungen sein, sich nach Beschäftigungsalternativen umzuschauen. Da jedoch auch im Umland der Stadt keine ausreichenden Möglichkeiten bestehen, die freigesetzten Arbeitskräfte aufzufangen, wird für viele Betroffene die einzige Alternative darin liegen, Visaginas auf der Suche nach einem neuen Arbeitsplatz zu verlassen. Die Tatsache, dass der Großteil der heutigen Einwohner aus anderen Unionsrepubliken der damaligen Sowjetunion nach Visaginas kam und nur selten über gute Kenntnisse in der Landessprache Litauisch verfügt, stellt dabei ein besonderes Problem dar. Der Arbeit lag folgende zentrale Fragestellung zugrunde: Warum wandern unter gleichen strukturellen (vor allem ökonomischen) Rahmenbedingungen Menschen aus Visaginas ab, während andere dies nicht tun bzw. eine Abwanderung gar nicht in Erwägung ziehen? Betreuer/Gutachter: Prof. Wilfried Heller; Prof. Sebastian Lentz
The Dead Sea Transform (DST) is a prominent shear zone in the Middle East. It separates the Arabian plate from the Sinai microplate and stretches from the Red Sea rift in the south via the Dead Sea to the Taurus-Zagros collision zone in the north. Formed in the Miocene about 17 Ma ago and related to the breakup of the Afro-Arabian continent, the DST accommodates the left-lateral movement between the two plates. The study area is located in the Arava Valley between the Dead Sea and the Red Sea, centered across the Arava Fault (AF), which constitutes the major branch of the transform in this region. A set of seismic experiments comprising controlled sources, linear profiles across the fault, and specifically designed receiver arrays reveals the subsurface structure in the vicinity of the AF and of the fault zone itself down to about 3-4 km depth. A tomographically determined seismic P velocity model shows a pronounced velocity contrast near the fault with lower velocities on the western side than east of it. Additionally, S waves from local earthquakes provide an average P-to-S velocity ratio in the study area, and there are indications for a variations across the fault. High-resolution tomographic velocity sections and seismic reflection profiles confirm the surface trace of the AF, and observed features correlate well with fault-related geological observations. Coincident electrical resistivity sections from magnetotelluric measurements across the AF show a conductive layer west of the fault, resistive regions east of it, and a marked contrast near the trace of the AF, which seems to act as an impermeable barrier for fluid flow. The correlation of seismic velocities and electrical resistivities lead to a characterisation of subsurface lithologies from their physical properties. Whereas the western side of the fault is characterised by a layered structure, the eastern side is rather uniform. The vertical boundary between the western and the eastern units seems to be offset to the east of the AF surface trace. A modelling of fault-zone reflected waves indicates that the boundary between low and high velocities is possibly rather sharp but exhibits a rough surface on the length scale a few hundreds of metres. This gives rise to scattering of seismic waves at this boundary. The imaging (migration) method used is based on array beamforming and coherency analysis of P-to-P scattered seismic phases. Careful assessment of the resolution ensures reliable imaging results. The western low velocities correspond to the young sedimentary fill in the Arava Valley, and the high velocities in the east reflect mainly Precambrian igneous rocks. A 7 km long subvertical scattering zone reflector is offset about 1 km east of the AF surface trace and can be imaged from 1 km to about 4 km depth. The reflector marks the boundary between two lithological blocks juxtaposed most probably by displacement along the DST. This interpretation as a lithological boundary is supported by the combined seismic and magnetotelluric analysis. The boundary may be a strand of the AF, which is offset from the current, recently active surface trace. The total slip of the DST may be distributed spatially and in time over these two strands and possibly other faults in the area.
In recent years, there has been a dramatic increase in available compute capacities. However, these “Grid resources” are rarely accessible in a continuous stream, but rather appear scattered across various machine types, platforms and operating systems, which are coupled by networks of fluctuating bandwidth. It becomes increasingly difficult for scientists to exploit available resources for their applications. We believe that intelligent, self-governing applications should be able to select resources in a dynamic and heterogeneous environment: Migrating applications determine a resource when old capacities are used up. Spawning simulations launch algorithms on external machines to speed up the main execution. Applications are restarted as soon as a failure is detected. All these actions can be taken without human interaction. A distributed compute environment possesses an intrinsic unreliability. Any application that interacts with such an environment must be able to cope with its failing components: deteriorating networks, crashing machines, failing software. We construct a reliable service infrastructure by endowing a service environment with a peer-to-peer topology. This “Grid Peer Services” infrastructure accommodates high-level services like migration and spawning, as well as fundamental services for application launching, file transfer and resource selection. It utilizes existing Grid technology wherever possible to accomplish its tasks. An Application Information Server acts as a generic information registry to all participants in a service environment. The service environment that we developed, allows applications e.g. to send a relocation requests to a migration server. The server selects a new computer based on the transmitted resource requirements. It transfers the application's checkpoint and binary to the new host and resumes the simulation. Although the Grid's underlying resource substrate is not continuous, we achieve persistent computations on Grids by relocating the application. We show with our real-world examples that a traditional genome analysis program can be easily modified to perform self-determined migrations in this service environment.