@phdthesis{Kopf2008, author = {Kopf, Markus}, title = {Zeeman-Doppler Imaging of active late-type stars}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-37387}, school = {Universit{\"a}t Potsdam}, year = {2008}, abstract = {Stellare Magnetfelder spielen eine wichtige Rolle bei der Entstehung und Entwicklung von Sternen. Leider entziehen sie sich aber, aufgrund ihrer großen Entfernung zur Erde, einer direkten Beobachtung. Dies gilt zumindest f{\"u}r derzeitige und in naher Zukunft zur Verf{\"u}gung stehende Instrumente. Um aber beispielsweise zu verstehen, ob Magnetfelder durch einen Dynamoprozess generiert werden oder {\"U}berbleibsel der Sternentstehung sind, ist es zwingend erforderlich, die Oberfl{\"a}chenstruktur und die zeitliche Entwicklung von stellaren Feldern zu untersuchen. Gl{\"u}cklicherweise haben wir mit der Dopplerverschiebung sowie der Polarisation von Licht Mittel zur Verf{\"u}gung, um indirekt die Magnetfeldtopologie entfernter Sternen zu rekonstruieren, wenn auch nur die schnell rotierender. Die auf den beiden genannten Effekten basierende Rekonstruktionsmethode ist unter dem Namen Zeeman-Doppler Imaging (ZDI) bekannt. Sie stellt eine leistungsf{\"a}hige Methode dar, um aus rotationsverbreiterten Stokes Profilen schnell rotierender Sterne Oberfl{\"a}chenkartierungen der Temperatur und Magnetfeldverteilung zu erstellen. Durch das ZDI konnten in den vergangenen Jahren die Magnetfeldverteilungen zahlreicher Sterne rekonstruiert werden. Diese Methode stellt allerdings sehr hohe Anforderungen sowohl an die Instrumentierung als auch an die Rechenleistung und ist deshalb h{\"a}ufig mit zahlreichen Annahmen und N{\"a}herungen verbunden. Ziel dieser Arbeit war es, Methoden f{\"u}r ein ZDI zu entwickeln, das darauf ausgelegt ist, zeitaufgel{\"o}ste spektropolarimetrische Daten von aktiven sp{\"a}ten Sternen zu invertieren. Es sollte also insbesondere den komplexen und lokalen Magnetfeldstrukturen dieser Sterne Rechnung getragen werden. Um die Orientierung und St{\"a}rke solcher Felder zuverl{\"a}ssig rekonstruieren zu k{\"o}nnen, sollte die Inversion im Stande sein, alle vier Stokes-Komponenten einzubeziehen. Ferner war vorgesehen auf vollst{\"a}ndigen polarisierten Strahlungstransportmodellierungen aufzubauen. Dies erm{\"o}glicht eine simultane und selbstkonsistente Temperatur- und Magnetfeld-Inversion, die damit dem komplexen Zusammenspiel zwischen Temperatur und Magnetfeld gerecht wird. Schließlich sollte die Anwendung eines neu zu entwickelnden ZDI Programms auf Stokes I und V Beobachtungen von II Pegasi (kurz: II Peg) erste Magnefeldkarten dieses sehr aktiven Sterns liefern. Um den hohen Rechenaufwand, der mit der Inversionsmethode einhergeht, besser bew{\"a}ltigen zu k{\"o}nnen, wurde zun{\"a}chst eine schnelle Approximationsmethode f{\"u}r den polarisierten Strahlungstransport entwickelt. Sie basiert auf einer Hauptkomponentenanalyse (PCA) sowie auf k{\"u}nstlichen Neuronalen Netzen. Letztere approximieren den funktionalen Zusammenhang zwischen atmosph{\"a}rischen Parametern und den zugeh{\"o}rigen lokalen Stokes Profilen. Inverse Probleme sind potentiell schlecht gestellt und erfordern in der Regel eine Regularisierung. Der entwickelte Ansatz verwendet eine lokale Entropie, die auf die Besonderheiten bei der Rekonstruktion lokalisierter Magnetfeder eingeht. Ein weiterer neuartiger Ansatz befasst sich mit der Rauschreduktion polarimetrischer Beobachtungsdaten. Er macht sich die Hauptkomponentenanalyse zu Nutze, um mit Hilfe einer Vielzahl beobachteter Spektrallinien, einzelne Linien mit drastisch vergr{\"o}ßertem Signal-zu-Rausch-Verh{\"a}ltnis wieder zu geben. Diese Methode hat gegen{\"u}ber anderen Multi-Spektrallinien-Verfahren den Vorteil, nach wie vor eine Inversion auf der Basis einzelner Spektrallinien durchf{\"u}hren zu k{\"o}nnen. Schließlich wurde das Inversionsprogramm iMap entwickelt, das die zuvor genannten Methoden implementiert. Detaillierte Testrechnungen demonstrieren die Funktionsf{\"a}higkeit und Genauigkeit der schnellen Synthese-Methode und weisen einen Zeitgewinn von nahezu drei Gr{\"o}ßenordnungen gegen{\"u}ber der konventionellen Strahlungstransportberechnung auf. Desweiteren untersuchen wir den Einfluss der verschiedenen Stokes Komponenten (IV bzw. IVQU) auf die Zuverl{\"a}ssigkeit, ein bekanntes Magnetfeld zu rekonstruieren. Damit belegen wir die Zuverl{\"a}ssigkeit unseres Inversionsprogrammes und zeigen dar{\"u}ber hinaus auch Einschr{\"a}nkungen von Magnetfeldinversionen im allgemeinen auf. Eine erste Inversion von Stokes I und V Profilen von II Peg liefert zum ersten Mal f{\"u}r diesen Stern simultan Temperatur- und Magnetfeldverteilungen.}, language = {en} } @book{Lang2008, author = {Lang, Thilo}, title = {Institutional perspectives of local development in Germany and England : a comparative study about regeneration in old industrial towns experiencing decline}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-37346}, publisher = {Universit{\"a}t Potsdam}, year = {2008}, abstract = {This research is about local actors' response to problems of uneven development and unemployment. Policies to combat these problems are usually connected to socio-economic regeneration in England and economic and employment promotion (Wirtschafts- und Besch{\"a}ftigungsf{\"o}rderung) in Germany. The main result of this project is a description of those factors which support the emergence of local socio-economic initiatives aimed at job creation. Eight social and formal economy initiatives have been examined and the ways in which their emergence has been influenced by institutional factors has been analysed. The role of local actors and forms of governance as well as wider regional and national policy frameworks has been taken into account. Socio-economic initiatives have been defined as non-routine local projects or schemes with the objective of direct job creation. Such initiatives often focus on specific local assets for the formal or the social economy. Socio-economic initiatives are grounded on ideas of local economic development, and the creation of local jobs for local people. The adopted understanding of governance focuses on the processes of decision taking. Thus, this understanding of governance is broadly construed to include the ways in which actors in addition to traditional government manage urban development. The applied understanding of governance lays a focus on 'strategic' forms of decision taking about both long term objectives and short term action linked to socio-economic regeneration. Four old industrial towns in North England and East Germany have been selected for case studies due to their particular socio-economic background. These towns, with between 10.000 and 70.000 inhabitants, are located outside of the main agglomerations and bear central functions for their hinterland. The approach has been comparative, with a focus on examining common themes rather than gaining in-depth knowledge of a single case. Until now, most urban governance studies have analysed the impacts of particular forms of governance such as regeneration partnerships. This project looks at particular initiatives and poses the question to what extent their emergence can be understood as a result of particular forms of governance, local institutional factors or regional and national contexts.}, language = {en} } @misc{BaerHenney2009, type = {Master Thesis}, author = {Baer-Henney, Dinah}, title = {On natural and probabilisic effects during acquisition of morphophonemic alternations}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-36819}, school = {Universit{\"a}t Potsdam}, year = {2009}, abstract = {The acquisition of phonological alternations consists of many aspects as discussions in the relevant literature show. There are contrary findings about the role of naturalness. A natural process is grounded in phonetics; they are easy to learn, even in second language acquisition when adults have to learn certain processes that do not occur in their native language. There is also evidence that unnatural - arbitrary - rules can be learned. Current work on the acquisition of morphophonemic alternations suggests that their probability of occurrence is a crucial factor in acquisition. I have conducted an experiment to investigate the effects of naturalness as well as of probability of occurrence with 80 adult native speakers of German. It uses the Artificial Grammar paradigm: Two artificial languages were constructed, each with a particular alternation. In one language the alternation is natural (vowel harmony); in the other language the alternation is arbitrary (a vowel alternation depends on the sonorancy of the first consonant of the stem). The participants were divided in two groups, one group listened to the natural alternation and the other group listened to the unnatural alternation. Each group was divided into two subgroups. One subgroup then was presented with material in which the alternation occurred frequently and the other subgroup was presented with material in which the alternation occurred infrequently. After this exposure phase every participant was asked to produce new words during the test phase. Knowledge about the language-specific alternation pattern was needed to produce the forms correctly as the phonological contexts demanded certain alternants. The group performances have been compared with respect to the effects of naturalness and probability of occurrence. The natural rule was learned more easily than the unnatural one. Frequently presented rules were not learned more easily than the ones that were presented less frequently. Moreover, participants did not learn the unnatural rule at all, whether this rule was presented frequently or infrequently did not matter. There was a tendency that the natural rule was learned more easily if presented frequently than if presented infrequently, but it was not significant due to variability across participants.}, language = {en} } @book{SmirnovWeidlichMendlingetal.2009, author = {Smirnov, Sergey and Weidlich, Matthias and Mendling, Jan and Weske, Mathias}, title = {Action patterns in business process models}, publisher = {Universit{\"a}tsverlag Potsdam}, address = {Potsdam}, isbn = {978-3-86956-009-0}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-33586}, publisher = {Universit{\"a}t Potsdam}, pages = {19}, year = {2009}, abstract = {Business process management experiences a large uptake by the industry, and process models play an important role in the analysis and improvement of processes. While an increasing number of staff becomes involved in actual modeling practice, it is crucial to assure model quality and homogeneity along with providing suitable aids for creating models. In this paper we consider the problem of offering recommendations to the user during the act of modeling. Our key contribution is a concept for defining and identifying so-called action patterns - chunks of actions often appearing together in business processes. In particular, we specify action patterns and demonstrate how they can be identified from existing process model repositories using association rule mining techniques. Action patterns can then be used to suggest additional actions for a process model. Our approach is challenged by applying it to the collection of process models from the SAP Reference Model.}, language = {en} } @phdthesis{MeyerLucht2009, author = {Meyer-Lucht, Yvonne}, title = {Does variability matter? Major histocompatibility complex (MHC) variation and its associations to parasitism in natural small mammal populations}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-36419}, school = {Universit{\"a}t Potsdam}, year = {2009}, abstract = {The adaptive evolutionary potential of a species or population to cope with omnipresent environmental challenges is based on its genetic variation. Variability at immune genes, such as the major histocompatibility complex (MHC) genes, is assumed to be a very powerful and effective tool to keep pace with diverse and rapidly evolving pathogens. In my thesis, I studied natural levels of variation at the MHC genes, which have a key role in immune defence, and parasite burden in different small mammal species. I assessed the importance of MHC variation for parasite burden in small mammal populations in their natural environment. To understand the processes shaping different patterns of MHC variation I focused on evidence of selection through pathogens upon the host. Further, I addressed the issue of low MHC diversity in populations or species, which could potentially arise as a result from habitat fragmentation and isolation. Despite their key role in the mammalian evolution the marsupial MHC has been rarely investigated. Studies on primarily captive or laboratory bred individuals indicated very little or even no polymorphism at the marsupial MHC class II genes. However, natural levels of marsupial MHC diversity and selection are unknown to date as studies on wild populations are virtually absent. I investigated MHC II variation in two Neotropical marsupial species endemic to the threatened Brazilian Atlantic Forest (Gracilinanus microtarsus, Marmosops incanus) to test whether the predicted low marsupial MHC class II polymorphism proves to be true under natural conditions. For the first time in marsupials I confirmed characteristics of MHC selection that were so far only known from eutherian mammals, birds, and fish: Positive selection on specific codon sites, recombination, and trans-species polymorphism. Beyond that, the two marsupial species revealed considerable differences in their MHC class II diversity. Diversity was rather low in M. incanus but tenfold higher in G. microtarsus, disproving the predicted general low marsupial MHC class II variation. As pathogens are believed to be very powerful drivers of MHC diversity, I studied parasite burden in both host species to understand the reasons for the remarkable differences in MHC diversity. In both marsupial species specific MHC class II variants were associated to either high or low parasite load highlighting the importance of the marsupial MHC class II in pathogen defence. I developed two alternative scenarios with regard to MHC variation, parasite load, and parasite diversity. In the 'evolutionary equilibrium' scenario I assumed the species with low MHC diversity, M. incanus, to be under relaxed pathogenic selection and expected low parasite diversity. Alternatively, low MHC diversity could be the result of a recent loss of genetic variation by means of a genetic bottleneck event. Under this 'unbalanced situation' scenario, I assumed a high parasite burden in M. incanus due to a lack of resistance alleles. Parasitological results clearly reject the first scenario and point to the second scenario, as M. incanus is distinctly higher parasitised but parasite diversity is relatively equal compared to G. microtarsus. Hence, I suggest that the parasite load in M. incanus is rather the consequence than the cause for its low MHC diversity. MHC variation and its associations to parasite burden have been typically studied within single populations but MHC variation between populations was rarely taken into account. To gain scientific insight on this issue, I chose a common European rodent species. In the yellow necked mouse (Apodemus flavicollis), I investigated the effects of genetic diversity on parasite load not on the individual but on the population level. I included populations, which possess different levels of variation at the MHC as well as at neutrally evolving genetic markers (microsatellites). I was able to show that mouse populations with a high MHC allele diversity are better armed against high parasite burdens highlighting the significance of adaptive genetic diversity in the field of conservation genetics. An individual itself will not directly benefit from its population's large MHC allele pool in terms of parasite resistance. But confronted with the multitude of pathogens present in the wild a population with a large MHC allele reservoir is more likely to possess individuals with resistance alleles. These results deepen our understanding of the complex causes and processes of evolutionary adaptations between hosts and pathogens.}, language = {en} } @phdthesis{Regel2008, author = {Regel, Stefanie}, title = {The comprehension of figurative language : electrophysiological evidence on the processing of irony}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-33376}, school = {Universit{\"a}t Potsdam}, year = {2008}, abstract = {Diese Dissertation untersucht das Verstehen figurativer Sprache, im Besonderen die zeitliche Verarbeitung von verbaler Ironie. In sechs Experimenten wurde mittels ereignis-korrelierter Potentiale (EKP) die Gehirnaktivit{\"a}t beim Verstehen ironischer {\"A}ußerungen im Vergleich zu entsprechenden nicht-ironischen {\"A}ußerungen gemessen und analysiert. Dar{\"u}berhinaus wurde der Einfluss verschiedener sprachbegleitender Hinweisreize, z.B. von Prosodie oder der Verwendung von Satzzeichen, sowie außersprachlicher Hinweisreize, wie bspw. pragmatischen Wissens, auf das Ironieverstehen untersucht. Auf Grundlage dieser Ergebnisse werden verschiedene psycholinguistische Modelle figurativer Sprachverarbeitung, d.h. 'standard pragmatic model', 'graded salience hypothesis', sowie 'direct access view', diskutiert.}, language = {en} } @phdthesis{Bange2009, author = {Bange, Sebastian}, title = {Transient optical and electrical effects in polymeric semiconductors}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-36314}, school = {Universit{\"a}t Potsdam}, year = {2009}, abstract = {Classical semiconductor physics has been continuously improving electronic components such as diodes, light-emitting diodes, solar cells and transistors based on highly purified inorganic crystals over the past decades. Organic semiconductors, notably polymeric, are a comparatively young field of research, the first light-emitting diode based on conjugated polymers having been demonstrated in 1990. Polymeric semiconductors are of tremendous interest for high-volume, low-cost manufacturing ("printed electronics"). Due to their rather simple device structure mostly comprising only one or two functional layers, polymeric diodes are much more difficult to optimize compared to small-molecular organic devices. Usually, functions such as charge injection and transport are handled by the same material which thus needs to be highly optimized. The present work contributes to expanding the knowledge on the physical mechanisms determining device performance by analyzing the role of charge injection and transport on device efficiency for blue and white-emitting devices, based on commercially relevant spiro-linked polyfluorene derivatives. It is shown that such polymers can act as very efficient electron conductors and that interface effects such as charge trapping play the key role in determining the overall device efficiency. This work contributes to the knowledge of how charges drift through the polymer layer to finally find neutral emissive trap states and thus allows a quantitative prediction of the emission color of multichromophoric systems, compatible with the observed color shifts upon driving voltage and temperature variation as well as with electrical conditioning effects. In a more methodically oriented part, it is demonstrated that the transient device emission observed upon terminating the driving voltage can be used to monitor the decay of geminately-bound species as well as to determine trapped charge densities. This enables direct comparisons with numerical simulations based on the known properties of charge injection, transport and recombination. The method of charge extraction under linear increasing voltages (CELIV) is investigated in some detail, correcting for errors in the published approach and highlighting the role of non-idealized conditions typically present in experiments. An improved method is suggested to determine the field dependence of charge mobility in a more accurate way. Finally, it is shown that the neglect of charge recombination has led to a misunderstanding of experimental results in terms of a time-dependent mobility relaxation.}, language = {en} } @phdthesis{Nikolovski2009, author = {Nikolovski, Nino}, title = {Pectin: New insights from an old polymer through pectinase-based genetic screens}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-35255}, school = {Universit{\"a}t Potsdam}, year = {2009}, abstract = {Pectic polysaccharides, a class of plant cell wall polymers, form one of the most complex networks known in nature. Despite their complex structure and their importance in plant biology, little is known about the molecular mechanism of their biosynthesis, modification, and turnover, particularly their structure-function relationship. One way to gain insight into pectin metabolism is the identification of mutants with an altered pectin structure. Those were obtained by a recently developed pectinase-based genetic screen. Arabidopsis thaliana seedlings grown in liquid medium containing pectinase solutions exhibited particular phenotypes: they were dwarfed and slightly chlorotic. However, when genetically different A. thaliana seed populations (random T-DNA insertional populations as well as EMS-mutagenized populations and natural variations) were subjected to this treatment, individuals were identified that exhibit a different visible phenotype compared to wild type or other ecotypes and may thus contain a different pectin structure (pec-mutants). After confirming that the altered phenotype occurs only when the pectinase is present, the EMS mutants were subjected to a detailed cell wall analysis with particular emphasis on pectins. This suite of mutants identified in this study is a valuable resource for further analysis on how the pectin network is regulated, synthesized and modified. Flanking sequences of some of the T-DNA lines have pointed toward several interesting genes, one of which is PEC100. This gene encodes a putative sugar transporter gene, which, based on our data, is implicated in rhamnogalacturonan-I synthesis. The subcellular localization of PEC100 was studied by GFP fusion and this protein was found to be localized to the Golgi apparatus, the organelle where pectin biosynthesis occurs. Arabidopsis ecotype C24 was identified as a susceptible one when grown with pectinases in liquid culture and had a different oligogalacturonide mass profile when compared to ecotype Col-0. Pectic oligosaccharides have been postulated to be signal molecules involved in plant pathogen defense mechanisms. Indeed, C24 showed elevated accumulation of reactive oxygen species upon pectinase elicitation and had altered response to the pathogen Alternaria brassicicola in comparison to Col-0. Using a recombinant inbred line population three major QTLs were identified to be responsible for the susceptibility of C24 to pectinases. In a reverse genetic approach members of the qua2 (putative pectin methyltransferase) family were tested for potential target genes that affect pectin methyl-esterification. The list of these genes was determined by in silico study of the pattern of expression and co-expression of all 34 members of this family resulting in 6 candidate genes. For only for one of the 6 analyzed genes a difference in the oligogalacturonide mass profile was observed in the corresponding knock-out lines, confirming the hypothesis that the methyl-esterification pattern of pectin is fine tuned by members of this gene family. This study of pectic polysaccharides through forward and reverse genetic screens gave new insight into how pectin structure is regulated and modified, and how these modifications could influence pectin mediated signalling and pathogenicity.}, language = {en} } @article{Ette2001, author = {Ette, Ottmar}, title = {The scientist as Weltb{\"u}rger}, series = {HIN : Alexander von Humboldt im Netz ; international review for Humboldtian studies}, volume = {II}, journal = {HIN : Alexander von Humboldt im Netz ; international review for Humboldtian studies}, number = {2}, publisher = {Universit{\"a}tsverlag Potsdam}, address = {Potsdam}, issn = {2568-3543}, doi = {10.18443/10}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-34546}, pages = {41 -- 62}, year = {2001}, language = {en} } @phdthesis{Stefer2009, author = {Stefer, Susanne}, title = {Late Pleistocene-Holocene sedimentary processes at the active margin of South-Central Chile : marine and lacustrine sediment records as archives of tectonics and climate variability}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-33731}, school = {Universit{\"a}t Potsdam}, year = {2009}, abstract = {Active continental margins are affected by complex feedbacks between tectonic, climate and surface processes, the intricate relations of which are still a matter of discussion. The Chilean convergent margin, forming the outstanding Andean subduction orogen, constitutes an ideal natural laboratory for the investigation of climate, tectonics and their interactions. In order to study both processes, I examined marine and lacustrine sediments from different depositional environments on- and offshore the south-central Chilean coast (38-40°S). I combined sedimentological, geochemical and isotopical analyses to identify climatic and tectonic signals within the sedimentary records. The investigation of marine trench sediments (ODP Site 1232, SONNE core 50SL) focused on frequency changes of turbiditic event layers since the late Pleistocene. In the active margin setting of south-central Chile, these layers were considered to reflect periodically occurring earthquakes and to constitute an archive of the regional paleoseismicity. The new results indicate glacial-interglacial changes in turbidite frequencies during the last 140 kyr, with short recurrence times (~200 years) during glacial and long recurrence times (~1000 years) during interglacial periods. Hence, the generation of turbidites appears to be strongly influenced by climate and sea level changes, which control on the amount of sediment delivered to the shelf edge and therewith the stability of the continental slope: more stable slope conditions during interglacial periods entail lower turbidite frequencies than in glacial periods. Since glacial turbidite recurrence times are congruent with earthquake recurrence times derived from the historical record and other paleoseismic archives of the region, I concluded that only during cold stages the sediment availability and slope instability enabled the complete series of large earthquakes to be recorded. The sediment transport to the shelf region is not only driven by climate conditions but also influenced by local forearc tectonics. Accelerating uplift rates along major tectonic structures involved drainage anomalies and river flow inversions, which seriously altered the sediment supply to the Pacific Ocean. Two examples for the tectonic hindrance of fluvial systems are the coastal lakes Lago Lanalhue and Lago Lleu Lleu. Both lakes developed within former river valleys, which once discharged towards the Pacific and were dammed by tectonically uplifted sills at ~8000 yr BP. Analyses of sediment cores from the lakes showed similar successions of marine/brackish deposits at the bottom, covered by lacustrine sediments on top. Dating of the transitions between these different units and the comparison with global sea level curves allowed me to calculate local Holocene uplift rates, which are distinctly higher for the upraised sills (Lanalhue: 8.83 ± 2.7 mm/yr, Lleu Lleu: 11.36 ± 1.77 mm/yr) than for the lake basins (Lanalhue: 0.42 ± 0.71 mm/yr, Lleu Lleu: 0.49 ± 0.44 mm/yr). I hence considered the sills to be the surface expression of a blind thrust associated with a prominent inverse fault that is controlling regional uplift and folding. After the final separation of Lago Lanalhue and Lago Lleu Lleu from the Pacific, a constant deposition of lacustrine sediments preserved continuous records of local environmental changes. Sequences from both lakes indicate a long-term climate trend with a significant shift from more arid conditions during the Mid-Holocene (8000 - 4200 cal yr BP) to more humid conditions during the Late Holocene (4200 cal yr BP - present). This trend is consistent with other regional paleoclimatic data and interpreted to reflect changes in the strength/position of the Southern Westerly Winds. Since ~5000 years, sediments of Lago Lleu Lleu are marked by numerous intercalated detrital layers that recur with a mean frequency of ~210 years. Deposition of these layers may be triggered by local tectonics (i.e. earthquakes), but may also originate from changes in the local climate (e.g. onset of modern ENSO conditions). During the last 2000 years, pronounced variations in the terrigenous sediment supply to both lakes suggest important hydrological changes on the centennial time-scale as well. A lower input of terrigenous matter points to less humid phases between 200 cal yr B.C. - 150 cal yr A.D., 900 - 1350 cal yr A.D. and 1850 cal yr A.D. to present (broadly corresponding to the Roman, Medieval, and Modern Warm Periods). More humid periods persisted from 150 - 900 cal yr A.D. and 1350 - 1850 cal yr A.D. (broadly corresponding to the Dark Ages and the Little Ice Age). In conclusion, the combined investigation of marine and lacustrine sediments is a feasible method for the reconstruction of climatic and tectonic processes on different time scales. My approach allows exploring both climate and tectonics in one and the same archive, and is largely transferable to other active margins worldwide.}, language = {en} } @misc{Krahe1992, author = {Krah{\´e}, Barbara}, title = {Coping with rape : a social psychological perspective}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-33973}, year = {1992}, abstract = {Content Social stereotypes and responsibility attributions to victims of rape Atributing responsibillty to rape victims: a German study Rape myth acceptance and responsibility judgments: a British study Police officers' definitions of rape A study on cognitive prototypes of rape Conclusion References}, language = {en} } @phdthesis{Biewald2008, author = {Biewald, Anne}, title = {A dynamic life cycle model for Germany with unemployment uncertainty}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-33111}, school = {Universit{\"a}t Potsdam}, year = {2008}, abstract = {This work analyzes the saving and consumption behavior of agents faced with the possibility of unemployment in a dynamic and stochastic life cycle model. The intertemporal optimization is based on Dynamic Programming with a backward recursion algorithm. The implemented uncertainty is not based on income shocks as it is done in traditional life cycle models but uses Markov probabilities where the probability for the next employment status of the agent depends on the current status. The utility function used is a CRRA function (constant relative risk aversion), combined with a CES function (constant elasticity of substitution) and has several consumption goods, a subsistence level, money and a bequest function.}, language = {en} } @phdthesis{Bickel2008, author = {Bickel, Steffen}, title = {Learning under differing training and test distributions}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-33331}, school = {Universit{\"a}t Potsdam}, year = {2008}, abstract = {One of the main problems in machine learning is to train a predictive model from training data and to make predictions on test data. Most predictive models are constructed under the assumption that the training data is governed by the exact same distribution which the model will later be exposed to. In practice, control over the data collection process is often imperfect. A typical scenario is when labels are collected by questionnaires and one does not have access to the test population. For example, parts of the test population are underrepresented in the survey, out of reach, or do not return the questionnaire. In many applications training data from the test distribution are scarce because they are difficult to obtain or very expensive. Data from auxiliary sources drawn from similar distributions are often cheaply available. This thesis centers around learning under differing training and test distributions and covers several problem settings with different assumptions on the relationship between training and test distributions-including multi-task learning and learning under covariate shift and sample selection bias. Several new models are derived that directly characterize the divergence between training and test distributions, without the intermediate step of estimating training and test distributions separately. The integral part of these models are rescaling weights that match the rescaled or resampled training distribution to the test distribution. Integrated models are studied where only one optimization problem needs to be solved for learning under differing distributions. With a two-step approximation to the integrated models almost any supervised learning algorithm can be adopted to biased training data. In case studies on spam filtering, HIV therapy screening, targeted advertising, and other applications the performance of the new models is compared to state-of-the-art reference methods.}, language = {en} } @book{OPUS4-3143, title = {Conceptual architecture patterns : FMC-based representations}, editor = {Gr{\"o}ne, Bernhard and Keller, Frank}, isbn = {978-3-935024-98-3}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-33173}, publisher = {Universit{\"a}t Potsdam}, year = {2004}, abstract = {This document presents the results of the seminar "Coneptual Arachitecture Patterns" of the winter term 2002 in the Hasso-Plattner-Institute. It is a compilation of the student's elaborations dealing with some conceptual architecture patterns which can be found in literature. One important focus laid on the runtime structures and the presentation of the patterns. 1. Introduction 1.1. The Seminar 1.2. Literature 2 Pipes and Filters (Andr{\´e} Langhorst and Martin Steinle) 3 Broker (Konrad H{\"u}bner and Einar L{\"u}ck) 4 Microkernel (Eiko B{\"u}ttner and Stefan Richter) 5 Component Configurator (Stefan R{\"o}ck and Alexander Gierak) 6 Interceptor (Marc F{\"o}rster and Peter Aschenbrenner) 7 Reactor (Nikolai Cieslak and Dennis Eder) 8 Half-Sync/Half-Async (Robert Mitschke and Harald Schubert) 9 Leader/Followers (Dennis Klemann and Steffen Schmidt)}, language = {en} } @book{OPUS4-3141, title = {Java language conversion assistant : an analysis}, editor = {Richter, Stefan and Henze, Stefan and B{\"u}ttner, Eiko and Bach, Steffen and Polze, Andreas}, publisher = {Universit{\"a}tsverlag Potsdam}, address = {Potsdam}, isbn = {978-3-937786-10-0}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-33151}, publisher = {Universit{\"a}t Potsdam}, pages = {166}, year = {2004}, abstract = {This document is an analysis of the 'Java Language Conversion Assistant'. Itr will also cover a language analysis of the Java Programming Language as well as a survey of related work concerning Java and C\# interoperability on the one hand and language conversion in general on the other. Part I deals with language analysis. Part II covers the JLCA tool and tests used to analyse the tool. Additionally, it gives an overview of the above mentioned related work. Part III presents a complete project that has been translated using the JLCA.}, language = {en} } @book{GroeneKnoepfelKugeletal.2004, author = {Gr{\"o}ne, Bernhard and Kn{\"o}pfel, Andreas and Kugel, Rudolf and Schmidt, Oliver}, title = {The Apache Modeling Project}, isbn = {978-3-937786-14-8}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-33147}, publisher = {Universit{\"a}t Potsdam}, year = {2004}, abstract = {This document presents an introduction to the Apache HTTP Server, covering both an overview and implementation details. It presents results of the Apache Modelling Project done by research assistants and students of the Hasso-Plattner-Institute in 2001, 2002 and 2003. The Apache HTTP Server was used to introduce students to the application of the modeling technique FMC, a method that supports transporting knowledge about complex systems in the domain of information processing (software and hardware as well). After an introduction to HTTP servers in general, we will focus on protocols and web technology. Then we will discuss Apache, its operational environment and its extension capabilities— the module API. Finally we will guide the reader through parts of the Apache source code and explain the most important pieces.}, language = {en} } @book{MeyerKuropka2005, author = {Meyer, Harald and Kuropka, Dominik}, title = {Requirements for service composition}, publisher = {Universit{\"a}tsverlag Potsdam}, address = {Potsdam}, isbn = {978-3-937786-81-0}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-33096}, publisher = {Universit{\"a}t Potsdam}, pages = {27}, year = {2005}, abstract = {1 Introduction 2 Use case Scenario 3 General Composition Requirements 4 Functional Requirements of Service Composition 5 Non-Functional Requirements 6 Conclusion}, language = {en} } @book{LinckelsMeinel2005, author = {Linckels, Serge and Meinel, Christoph}, title = {An e-librarian service : natural language interface for an efficient semantic search within multimedia resources}, publisher = {Universit{\"a}tsverlag Potsdam}, address = {Potsdam}, isbn = {978-3-937786-89-6}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-33088}, publisher = {Universit{\"a}t Potsdam}, pages = {40}, year = {2005}, abstract = {1 Introduction 1.1 Project formulation 1.2 Our contribution 2 Pedagogical Aspect 4 2.1 Modern teaching 2.2 Our Contribution 2.2.1 Autonomous and exploratory learning 2.2.2 Human machine interaction 2.2.3 Short multimedia clips 3 Ontology Aspect 3.1 Ontology driven expert systems 3.2 Our contribution 3.2.1 Ontology language 3.2.2 Concept Taxonomy 3.2.3 Knowledge base annotation 3.2.4 Description Logics 4 Natural language approach 4.1 Natural language processing in computer science 4.2 Our contribution 4.2.1 Explored strategies 4.2.2 Word equivalence 4.2.3 Semantic interpretation 4.2.4 Various problems 5 Information Retrieval Aspect 5.1 Modern information retrieval 5.2 Our contribution 5.2.1 Semantic query generation 5.2.2 Semantic relatedness 6 Implementation 6.1 Prototypes 6.2 Semantic layer architecture 6.3 Development 7 Experiments 7.1 Description of the experiments 7.2 General characteristics of the three sessions, instructions and procedure 7.3 First Session 7.4 Second Session 7.5 Third Session 7.6 Discussion and conclusion 8 Conclusion and future work 8.1 Conclusion 8.2 Open questions A Description Logics B Probabilistic context-free grammars}, language = {en} } @book{HuCordelMeinel2006, author = {Hu, Ji and Cordel, Dirk and Meinel, Christoph}, title = {A virtual machine architecture for creating IT-security laboratories}, publisher = {Universit{\"a}tsverlag Potsdam}, address = {Potsdam}, isbn = {978-3-939469-13-1}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-33077}, publisher = {Universit{\"a}t Potsdam}, pages = {50}, year = {2006}, abstract = {E-learning is a flexible and personalized alternative to traditional education. Nonetheless, existing e-learning systems for IT security education have difficulties in delivering hands-on experience because of the lack of proximity. Laboratory environments and practical exercises are indispensable instruction tools to IT security education, but security education in con-ventional computer laboratories poses the problem of immobility as well as high creation and maintenance costs. Hence, there is a need to effectively transform security laboratories and practical exercises into e-learning forms. This report introduces the Tele-Lab IT-Security architecture that allows students not only to learn IT security principles, but also to gain hands-on security experience by exercises in an online laboratory environment. In this architecture, virtual machines are used to provide safe user work environments instead of real computers. Thus, traditional laboratory environments can be cloned onto the Internet by software, which increases accessibilities to laboratory resources and greatly reduces investment and maintenance costs. Under the Tele-Lab IT-Security framework, a set of technical solutions is also proposed to provide effective functionalities, reliability, security, and performance. The virtual machines with appropriate resource allocation, software installation, and system configurations are used to build lightweight security laboratories on a hosting computer. Reliability and availability of laboratory platforms are covered by the virtual machine management framework. This management framework provides necessary monitoring and administration services to detect and recover critical failures of virtual machines at run time. Considering the risk that virtual machines can be misused for compromising production networks, we present security management solutions to prevent misuse of laboratory resources by security isolation at the system and network levels. This work is an attempt to bridge the gap between e-learning/tele-teaching and practical IT security education. It is not to substitute conventional teaching in laboratories but to add practical features to e-learning. This report demonstrates the possibility to implement hands-on security laboratories on the Internet reliably, securely, and economically.}, language = {en} } @book{HagedornSchoebelUflackeretal.2007, author = {Hagedorn, Benjamin and Sch{\"o}bel, Michael and Uflacker, Matthias and Copaciu, Flavius and Milanovic, Nikola}, title = {Proceedings of the fall 2006 workshop of the HPI research school on service-oriented systems engineering}, publisher = {Universit{\"a}tsverlag Potsdam}, address = {Potsdam}, isbn = {978-3-939469-58-2}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-33052}, publisher = {Universit{\"a}t Potsdam}, pages = {Getr. Z{\"a}hlung}, year = {2007}, abstract = {1. Design and Composition of 3D Geoinformation Services Benjamin Hagedorn 2. Operating System Abstractions for Service-Based Systems Michael Sch{\"o}bel 3. A Task-oriented Approach to User-centered Design of Service-Based Enterprise Applications Matthias Uflacker 4. A Framework for Adaptive Transport in Service- Oriented Systems based on Performance Prediction Flavius Copaciu 5. Asynchronicity and Loose Coupling in Service-Oriented Architectures Nikola Milanovic}, language = {en} } @book{NienhausGoochDoellner2006, author = {Nienhaus, Marc and Gooch, Bruce and D{\"o}llner, J{\"u}rgen Roland Friedrich}, title = {Visualizing movement dynamics in virtual urban environments}, publisher = {Universit{\"a}tsverlag Potsdam}, address = {Potsdam}, isbn = {978-3-939469-52-0}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-33065}, publisher = {Universit{\"a}t Potsdam}, pages = {7}, year = {2006}, abstract = {Dynamics in urban environments encompasses complex processes and phenomena such as related to movement (e.g.,traffic, people) and development (e.g., construction, settlement). This paper presents novel methods for creating human-centric illustrative maps for visualizing the movement dynamics in virtual 3D environments. The methods allow a viewer to gain rapid insight into traffic density and flow. The illustrative maps represent vehicle behavior as light threads. Light threads are a familiar visual metaphor caused by moving light sources producing streaks in a long-exposure photograph. A vehicle's front and rear lights produce light threads that convey its direction of motion as well as its velocity and acceleration. The accumulation of light threads allows a viewer to quickly perceive traffic flow and density. The light-thread technique is a key element to effective visualization systems for analytic reasoning, exploration, and monitoring of geospatial processes.}, language = {en} } @phdthesis{Brune2009, author = {Brune, Sascha}, title = {Landslide generated tsunamis : numerical modeling and real-time prediction}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-32986}, school = {Universit{\"a}t Potsdam}, year = {2009}, abstract = {Submarine landslides can generate local tsunamis posing a hazard to human lives and coastal facilities. Two major related problems are: (i) quantitative estimation of tsunami hazard and (ii) early detection of the most dangerous landslides. This thesis focuses on both those issues by providing numerical modeling of landslide-induced tsunamis and by suggesting and justifying a new method for fast detection of tsunamigenic landslides by means of tiltmeters. Due to the proximity to the Sunda subduction zone, Indonesian coasts are prone to earthquake, but also landslide tsunamis. The aim of the GITEWS-project (German-Indonesian Tsunami Early Warning System) is to provide fast and reliable tsunami warnings, but also to deepen the knowledge about tsunami hazards. New bathymetric data at the Sunda Arc provide the opportunity to evaluate the hazard potential of landslide tsunamis for the adjacent Indonesian islands. I present nine large mass movements in proximity to Sumatra, Java, Sumbawa and Sumba, whereof the largest event displaced 20 km³ of sediments. Using numerical modeling, I compute the generated tsunami of each event, its propagation and runup at the coast. Moreover, I investigate the age of the largest slope failures by relating them to the Great 1977 Sumba earthquake. Continental slopes off northwest Europe are well known for their history of huge underwater landslides. The current geological situation west of Spitsbergen is comparable to the continental margin off Norway after the last glaciation, when the large tsunamigenic Storegga slide took place. The influence of Arctic warming on the stability of the Svalbard glacial margin is discussed. Based on new geophysical data, I present four possible landslide scenarios and compute the generated tsunamis. Waves of 6 m height would be capable of reaching northwest Europe threatening coastal areas. I present a novel technique to detect large submarine landslides using an array of tiltmeters, as a possible tool in future tsunami early warning systems. The dislocation of a large amount of sediment during a landslide produces a permanent elastic response of the earth. I analyze this response with a mathematical model and calculate the theoretical tilt signal. Applications to the hypothetical Spitsbergen event and the historical Storegga slide show tilt signals exceeding 1000 nrad. The amplitude of landslide tsunamis is controlled by the product of slide volume and maximal velocity (slide tsunamigenic potential). I introduce an inversion routine that provides slide location and tsunamigenic potential, based on tiltmeter measurements. The accuracy of the inversion and of the estimated tsunami height near the coast depends on the noise level of tiltmeter measurements, the distance of tiltmeters from the slide, and the slide tsunamigenic potential. Finally, I estimate the applicability scope of this method by employing it to known landslide events worldwide.}, language = {en} } @misc{Haakh2009, type = {Master Thesis}, author = {Haakh, Harald Richard}, title = {Cavity QED with superconductors and its application to the Casimir effect}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-32564}, school = {Universit{\"a}t Potsdam}, year = {2009}, abstract = {Diese Diplomarbeit untersucht den Casimir-Effekt zwischen normal- und supraleitenden Platten {\"u}ber einen weiten Temperaturbereich, sowie die Casimir-Polder-Wechselwirkung zwischen einem Atom und einer solchen Oberfl{\"a}che. Hierzu wurden vorwiegend numerische und asymptotische Rechnungen durchgef{\"u}hrt. Die optischen Eigenschaften der Oberfl{\"a}chen werden dann aus dielektrischen Funktionen oder optischen Leitf{\"a}higkeiten erhalten. Wichtige Modellen werden vorgestellt und insbesondere im Hinblick auf ihre analytischen und kausalen Eigenschaften untersucht. Es wird vorgestellt, wie sich die Casimir-Energie zwischen zwei normalleitenden Platten berechnen l{\"a}sst. Fr{\"u}here Arbeiten {\"u}ber den in allen metallischen Kavit{\"a}ten vorhandenen Beitrag von Oberfl{\"a}chenplasmonen zur Casimir-Wechselwirkung wurden zum ersten mal auf endliche Temperaturen erweitert. F{\"u}r Supraleiter wird eine analytische Fortsetzung der BCS-Leitf{\"a}higkeiten zu rein imagin{\"a}ren Frequenzen, sowohl innerhalb wie außerhalb des schmutzigen Grenzfalles verschwindender mittlerer freier Wegl{\"a}nge vorgestellt. Es wird gezeigt, dass die aus dieser neuen Beschreibung erhaltene freie Casimir-Energie in bestimmten Bereichen der Materialparameter hervorragend mit der im Rahmen des Zwei-Fluid-Modells f{\"u}r den Supraleiter berechneten {\"u}bereinstimmt. Die Casimir-Entropie einer supraleitenden Kavit{\"a}t erf{\"u}llt den Nernstschen W{\"a}rmesatz und weist einen charakteristischen Sprung beim Erreichen des supraleitenden Phasen{\"u}bergangs auf. Diese Effekte treten ebenfalls in der magnetischen Casimir-Polder-Wechselwirkung eines Atoms mit einer supraleitenden Oberfl{\"a}che auf. Es wird ferner gezeigt, dass die magnetische Dipol-Wechselwirkung eines Atomes mit einem Metall sehr stark von den dissipativen Eigenschaften und insbesondere von den Oberfl{\"a}chenstr{\"o}men abh{\"a}ngt. Dies f{\"u}hrt zu einer starken Unterdr{\"u}ckung der magnetischen Casimir-Polder-Energie bei endlichen Temperaturen und Abst{\"a}nden oberhalb der thermischen Wellenl{\"a}nge. Die Casimir-Polder-Entropie verletzt in einigen Modellen den Nernstschen W{\"a}rmesatz.{\"A}hnliche Effekte werden f{\"u}r den Casimir-Effekt zwischen Platten kontrovers diskutiert. In den entsprechenden elektrischen Dipol-Wechselwirkungen tritt keiner dieser Effekte auf. Die Ergebnisse dieser Arbeit legen nahe, das bekannte Plasma-Modells als Grenzfall eines Supraleiters bei niedrigen Temperaturen (bekannt als London-Theorie) zu betrachten, statt als Beschreibung eines normales Metalles. Supraleiter bieten die M{\"o}glichkeit, die Dissipation der Oberfl{\"a}chenstr{\"o}me in hohem Maße zu steuern. Dies k{\"o}nnte einen experimentellen Zugang zu den optischen Eigenschaften von Metallen bei niedrigen Frequenzen erlauben, die eng mit dem thermischen Casimir-Effekt verkn{\"u}pft sind. Anders als in entsprechenden Mikrowellen-Experimenten sind hierbei die Energien und Impulse unabh{\"a}ngige Gr{\"o}ßen. Die Messung der Oberfl{\"a}chenwechselwirkung zwischen Atomen und Supraleitern ist mit den heute verf{\"u}gbaren Atomfallen auf Mikrochips m{\"o}glich und der magnetische Anteil der Wechselwirkung sollte spektroskopischen Techniken zug{\"a}nglich sein}, language = {en} } @book{WistWollowski2007, author = {Wist, Dominic and Wollowski, Ralf}, title = {STG decomposition : avoiding irreducible CSC conflicts by internal communication}, isbn = {978-3-940793-02-7}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-32968}, publisher = {Universit{\"a}t Potsdam}, year = {2007}, abstract = {Inhalt: 1 Introduction 2 Basic Definitions 3 Achieving SI Implementability by Internal Communication 4 Towards a Structural Method 5 Examples 6 Conclusions and Future Work}, language = {en} } @book{PolyvyanyySmirnovWeske2008, author = {Polyvyanyy, Artem and Smirnov, Sergey and Weske, Mathias}, title = {Reducing the complexity of large EPCs}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-32959}, publisher = {Universit{\"a}t Potsdam}, year = {2008}, abstract = {Inhalt: 1 Introduction 2 Motivation and Goal 3 Fundamentals 4 Elementary Abstractions 5 Real World Example 6 Conclusions}, language = {en} } @book{MeinelSackBross2008, author = {Meinel, Christoph and Sack, Harald and Bross, Justus}, title = {Erster Deutscher IPv6 Gipfel}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-32865}, publisher = {Universit{\"a}t Potsdam}, year = {2008}, abstract = {Inhalt: KOMMUNIQU{\´E} GRUßWORT PROGRAMM HINTERGR{\"U}NDE UND FAKTEN REFERENTEN: BIOGRAFIE \& VOTRAGSZUSAMMENFASSUNG 1.) DER ERSTE DEUTSCHE IPV6 GIPFEL AM HASSO PLATTNER INSTITUT IN POTSDAM - PROF. DR. CHRISTOPH MEINEL - VIVIANE REDING 2.) IPV6, ITS TIME HAS COME - VINTON CERF 3.) DIE BEDEUTUNG VON IPV6 F{\"U}R DIE {\"O}FFENTLICHE VERWALTUNG IN DEUTSCHLAND - MARTIN SCHALLBRUCH 4.) TOWARDS THE FUTURE OF THE INTERNET - PROF. DR. LUTZ HEUSER 5.) IPV6 STRATEGY \& DEPLOYMENT STATUS IN JAPAN - HIROSHI MIYATA 6.) IPV6 STRATEGY \& DEPLOYMENT STATUS IN CHINA - PROF. WU HEQUAN 7.) IPV6 STRATEGY AND DEPLOYMENT STATUS IN KOREA - DR. EUNSOOK KIM 8.) IPV6 DEPLOYMENT EXPERIENCES IN GREEK SCHOOL NETWORK - ATHANASSIOS LIAKOPOULOS 9.) IPV6 NETWORK MOBILITY AND IST USAGE - JEAN-MARIE BONNIN 10.) IPV6 - R{\"U}STZEUG F{\"U}R OPERATOR \& ISP IPV6 DEPLOYMENT UND STRATEGIEN DER DEUTSCHEN TELEKOM - HENNING GROTE 11.) VIEW FROM THE IPV6 DEPLOYMENT FRONTLINE - YVES POPPE 12.) DEPLOYING IPV6 IN MOBILE ENVIRONMENTS - WOLFGANG FRITSCHE 13.) PRODUCTION READY IPV6 FROM CUSTOMER LAN TO THE INTERNET - LUTZ DONNERHACKE 14.) IPV6 - DIE BASIS F{\"U}R NETZWERKZENTRIERTE OPERATIONSF{\"U}HRUNG (NETOPF{\"U}) IN DER BUNDESWEHR HERAUSFORDERUNGEN - ANWENDUNGSFALLBETRACHTUNGEN - AKTIVIT{\"A}TEN - CARSTEN HATZIG 15.) WINDOWS VISTA \& IPV6 - BERND OURGHANLIAN 16.) IPV6 \& HOME NETWORKING TECHINCAL AND BUSINESS CHALLENGES - DR. TAYEB BEN MERIEM 17.) DNS AND DHCP FOR DUAL STACK NETWORKS - LAWRENCE HUGHES 18.) CAR INDUSTRY: GERMAN EXPERIENCE WITH IPV6 - AMARDEO SARMA 19.) IPV6 \& AUTONOMIC NETWORKING - RANGANAI CHAPARADZA 20.) P2P \& GRID USING IPV6 AND MOBILE IPV6 - DR. LATIF LADID}, language = {en} } @book{OPUS4-3118, title = {Proceedings of the 2. Ph.D. retreat of the HPI Research School on Service-oriented Systems Engineering}, editor = {Meinel, Christoph and Polze, Andreas and Weske, Mathias and D{\"o}llner, J{\"u}rgen Roland Friedrich and Hirschfeld, Robert and Naumann, Felix and Giese, Holger and Plattner, Hasso}, publisher = {Universit{\"a}tsverlag Potsdam}, address = {Potsdam}, isbn = {978-3-940793-42-3}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-32887}, publisher = {Universit{\"a}t Potsdam}, pages = {Getr. Z{\"a}hlung}, year = {2008}, abstract = {Contents 1. Styling for Service-Based 3D Geovisualization Benjamin Hagedorn 2. The Windows Monitoring Kernel Michael Sch{\"o}bel 3. A Resource-Oriented Information Network Platform for Global Design Processes Matthias Uflacker 4. Federation in SOA - Secure Service Invocation across Trust Domains Michael Menzel 5. KStruct: A Language for Kernel Runtime Inspection Alexander Schmidt 6. Deconstructing Resources Hagen Overdick 7. FMC-QE - Case Studies Stephan Kluth 8. A Matter of Trust Rehab Al-Nemr 9. From Semi-automated Service Composition to Semantic Conformance Harald Meyer}, language = {en} } @phdthesis{Zimmermann2009, author = {Zimmermann, Alexander}, title = {Rainfall redistribution and change of water quality in tropical forest canopies : patterns and persistence}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-32556}, school = {Universit{\"a}t Potsdam}, year = {2009}, abstract = {Motivations and research objectives: During the passage of rain water through a forest canopy two main processes take place. First, water is redistributed; and second, its chemical properties change substantially. The rain water redistribution and the brief contact with plant surfaces results in a large variability of both throughfall and its chemical composition. Since throughfall and its chemistry influence a range of physical, chemical and biological processes at or below the forest floor the understanding of throughfall variability and the prediction of throughfall patterns potentially improves the understanding of near-surface processes in forest ecosystems. This thesis comprises three main research objectives. The first objective is to determine the variability of throughfall and its chemistry, and to investigate some of the controlling factors. Second, I explored throughfall spatial patterns. Finally, I attempted to assess the temporal persistence of throughfall and its chemical composition. Research sites and methods: The thesis is based on investigations in a tropical montane rain forest in Ecuador, and lowland rain forest ecosystems in Brazil and Panama. The first two studies investigate both throughfall and throughfall chemistry following a deterministic approach. The third study investigates throughfall patterns with geostatistical methods, and hence, relies on a stochastic approach. Results and Conclusions: Throughfall is highly variable. The variability of throughfall in tropical forests seems to exceed that of many temperate forests. These differences, however, do not solely reflect ecosystem-inherent characteristics, more likely they also mirror management practices. Apart from biotic factors that influence throughfall variability, rainfall magnitude is an important control. Throughfall solute concentrations and solute deposition are even more variable than throughfall. In contrast to throughfall volumes, the variability of solute deposition shows no clear differences between tropical and temperate forests, hence, biodiversity is not a strong predictor of solute deposition heterogeneity. Many other factors control solute deposition patterns, for instance, solute concentration in rainfall and antecedent dry period. The temporal variability of the latter factors partly accounts for the low temporal persistence of solute deposition. In contrast, measurements of throughfall volume are quite stable over time. Results from the Panamanian research site indicate that wet and dry areas outlast consecutive wet seasons. At this research site, throughfall exhibited only weak or pure nugget autocorrelation structures over the studies lag distances. A close look at the geostatistical tools at hand provided evidence that throughfall datasets, in particular those of large events, require robust variogram estimation if one wants to avoid outlier removal. This finding is important because all geostatistical throughfall studies that have been published so far analyzed their data using the classical, non-robust variogram estimator.}, language = {en} } @book{HerschelNaumann2008, author = {Herschel, Melanie and Naumann, Felix}, title = {Space and time scalability of duplicate detection in graph data}, isbn = {978-3-940793-46-1}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-32851}, publisher = {Universit{\"a}t Potsdam}, year = {2008}, abstract = {Duplicate detection consists in determining different representations of real-world objects in a database. Recent research has considered the use of relationships among object representations to improve duplicate detection. In the general case where relationships form a graph, research has mainly focused on duplicate detection quality/effectiveness. Scalability has been neglected so far, even though it is crucial for large real-world duplicate detection tasks. In this paper we scale up duplicate detection in graph data (DDG) to large amounts of data and pairwise comparisons, using the support of a relational database system. To this end, we first generalize the process of DDG. We then present how to scale algorithms for DDG in space (amount of data processed with limited main memory) and in time. Finally, we explore how complex similarity computation can be performed efficiently. Experiments on data an order of magnitude larger than data considered so far in DDG clearly show that our methods scale to large amounts of data not residing in main memory.}, language = {en} } @book{PolyvyanyySmirnovWeske2008, author = {Polyvyanyy, Artem and Smirnov, Sergey and Weske, Mathias}, title = {The triconnected abstraction of process models}, publisher = {Universit{\"a}tsverlag Potsdam}, address = {Potsdam}, isbn = {978-3-940793-65-2}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-32847}, publisher = {Universit{\"a}t Potsdam}, pages = {17}, year = {2008}, abstract = {Contents: Artem Polyvanny, Sergey Smirnow, and Mathias Weske The Triconnected Abstraction of Process Models 1 Introduction 2 Business Process Model Abstraction 3 Preliminaries 4 Triconnected Decomposition 4.1 Basic Approach for Process Component Discovery 4.2 SPQR-Tree Decomposition 4.3 SPQR-Tree Fragments in the Context of Process Models 5 Triconnected Abstraction 5.1 Abstraction Rules 5.2 Abstraction Algorithm 6 Related Work and Conclusions}, language = {en} } @phdthesis{Popov2008, author = {Popov, Anton}, title = {Three-dimensional thermo-mechanical modeling of deformation at plate boundaries : case study San Andreas Fault System}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-31875}, school = {Universit{\"a}t Potsdam}, year = {2008}, abstract = {It has always been enigmatic which processes control the accretion of the North American terranes towards the Pacific plate and the landward migration of the San Andreas plate boundary. One of the theories suggests that the Pacific plate first cools and captures the uprising mantle in the slab window, and then it causes the accretion of the continental crustal blocks. The alternative theory attributes the accretion to the capture of Farallon plate fragments (microplates) stalled in the ceased Farallon-North America subduction zone. Quantitative judgement between these two end-member concepts requires a 3D thermomechanical numerical modeling. However, the software tool required for such modeling is not available at present in the geodynamic modeling community. The major aim of the presented work is comprised basically of two interconnected tasks. The first task is the development and testing of the research Finite Element code with sufficiently advanced facilities to perform the three-dimensional geological time scale simulations of lithospheric deformation. The second task consists in the application of the developed tool to the Neogene deformations of the crust and the mantle along the San Andreas Fault System in Central and northern California. The geological time scale modeling of lithospheric deformation poses numerous conceptual and implementation challenges for the software tools. Among them is the necessity to handle the brittle-ductile transition within the single computational domain, adequately represent the rock rheology in a broad range of temperatures and stresses, and resolve the extreme deformations of the free surface and internal boundaries. In the framework of this thesis the new Finite Element code (SLIM3D) has been successfully developed and tested. This code includes a coupled thermo-mechanical treatment of deformation processes and allows for an elasto-visco-plastic rheology with diffusion, dislocation and Peierls creep mechanisms and Mohr-Coulomb plasticity. The code incorporates an Arbitrary Lagrangian Eulerian formulation with free surface and Winkler boundary conditions. The modeling technique developed is used to study the aspects influencing the Neogene lithospheric deformation in central and northern California. The model setup is focused on the interaction between three major tectonic elements in the region: the North America plate, the Pacific plate and the Gorda plate, which join together near the Mendocino Triple Junction. Among the modeled effects is the influence of asthenosphere upwelling in the opening slab window on the overlying North American plate. The models also incorporate the captured microplate remnants in the fossil Farallon subduction zone, simplified subducting Gorda slab, and prominent crustal heterogeneity such as the Salinian block. The results show that heating of the mantle roots beneath the older fault zones and the transpression related to fault stepping, altogether, render cooling in the slab window alone incapable to explain eastward migration of the plate boundary. From the viewpoint of the thermomechanical modeling, the results confirm the geological concept, which assumes that a series of microplate capture events has been the primary reason of the inland migration of the San Andreas plate boundary over the recent 20 Ma. The remnants of the Farallon slab, stalled in the fossil subduction zone, create much stronger heterogeneity in the mantle than the cooling of the uprising asthenosphere, providing the more efficient and direct way for transferring the North American terranes to Pacific plate. The models demonstrate that a high effective friction coefficient on major faults fails to predict the distinct zones of strain localization in the brittle crust. The magnitude of friction coefficient inferred from the modeling is about 0.075, which is far less than typical values 0.6 - 0.8 obtained by variety of borehole stress measurements and laboratory data. Therefore, the model results presented in this thesis provide additional independent constrain which supports the "weak-fault" hypothesis in the long-term ongoing debate over the strength of major faults in the SAFS.}, language = {en} } @phdthesis{Kristen2009, author = {Kristen, Iris}, title = {Investigations on rainfall variability during the late Quaternary based on geochemical analyses of lake sediments from tropical and subtropical southern Africa}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-32547}, school = {Universit{\"a}t Potsdam}, year = {2009}, abstract = {This thesis presents investigations on sediments from two African lakes which have been recording changes in their surrounding environmental and climate conditions since more than 200,000 years. Focus of this work is the time of the last Glacial and the Holocene (the last ~100,000 years before present [in the following 100 kyr BP]). One important precondition for this kind of research is a good understanding of the present ecosystems in and around the lakes and of the sediment formation under modern climate conditions. Both studies therefore include investigations on the modern environment (including organisms, soils, rocks, lake water and sediments). A 90 m long sediment sequence was investigated from Lake Tswaing (north-eastern South Africa) using geochemical analyses. These investigations document alternating periods of high detrital input and low (especially autochthonous) organic matter content and periods of low detrital input, carbonatic or evaporitic sedimentation and high autochthonous organic matter content. These alternations are interpreted as changes between relatively humid and arid conditions, respectively. Before c. 75 kyr BP, they seem to follow changes in local insolation whereas afterwards they appear to be acyclic and are probably caused by changes in ocean circulation and/or in the mean position of the Inter-Tropical Convergence Zone (ITCZ). Today, these factors have main influence on precipitation in this area where rainfall occurs almost exclusively during austral summer. All modern organisms were analysed for their biomarker and bulk organic and compound-specific stable carbon isotope composition. The same investigations on sediments from the modern lake floor document the mixed input of the investigated individual organisms and reveal additional influences by methanotrophic bacteria. A comparison of modern sediment characteristics with those of sediments covering the time 14 to 2 kyr BP shows changes in the productivity of the lake and the surrounding vegetation which are best explained by changes in hydrology. More humid conditions are indicated for times older than 10 kyr BP and younger than 7.5 kyr BP, whereas arid conditions prevailed in between. These observations agree with the results from sediment composition and indications from other climate archives nearby. The second lake study deals with Lake Challa, a small, deep crater lake on the foot of Mount Kilimanjaro. In this lake form mm-scale laminated sediments which were analyses with micro-XRF scanning for changes in the element composition. By comparing these results with investigations on thin sections, results from ongoing sediment trap studies, meteorological data, and investigations on the surrounding rocks and soils, I develop a model for seasonal variability in the limnology and sedimentation of Lake Challa. The lake appears to be stratified during the warm rain seasons (October - December and March - May) during which detrital material is delivered to the lake and carbonates precipitate. On the lake floor forms a dark lamina with high contents of Fe and Ti and high Ca/Al and low Mn/Fe ratios. Diatoms bloom during the cool and windy season (June - September) when mixing down to c. 60 m depth provides easily bio-available nutrients. Contemporaneously, Fe and Mn-oxides are precipitating which cause high Mn/Fe ratios in the light diatom-rich laminae of the sediments. Trends in the Mn/Fe ratio of the sediments are interpreted to reflect changes in the intensity or duration of seasonal mixing in Lake Challa. This interpretation is supported by parallel changes in the organic matter and biogenic silica content observed in the 22 m long profile recovered from Lake Challa. This covers the time of the last 25 kyr BP. It documents a transition around 16 kyr BP from relatively well-mixed conditions with high detrital input during glacial times to stronger stratified conditions which are probably related to increasing lake levels in Challa and generally more humid conditions in East Africa. Intensified mixing is recorded for the time of the Younger Dryas and the period between 11.4 and 10.7 kyr BP. For these periods, reduced intensity of the SW monsoon and intensified NE monsoon are reported from archives of the Indian-Asian Monsoon region, arguing for the latter as a probable source for wind mixing in Lake Challa. This connection is probably also responsible for contemporaneous events in the Mn/Fe ratios of the Lake Challa sediments and in other records of northern hemisphere monsoon intensity during the Holocene and underlines the close interaction of global low latitude atmospheric circulation.}, language = {en} } @misc{OPUS4-3083, title = {Renaissance Linguistics Archive (1.0)}, editor = {Tavoni, Mirko and Flood, John and Lardet, Pierre and Haßler, Gerda and Damis-Sch{\"a}fer, Christine and Van Hal, Toon}, isbn = {978-3-940793-99-7}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-32068}, pages = {3605}, year = {2009}, abstract = {The bibliographic project 'Renaissance Linguistics Archive' (R.L.A.) aimed at establishing a comprehensive database of secondary sources covering the linguistics ideas developed by Renaissance scholars in Europe. The database project, founded in 1986 by Mirko Tavoni (Pisa) and in 1994 transferred to Gerda Haßler (Potsdam), resulted so far in three print-outs, each of them counting 1000 records. It is the aim of this website to publish the results of the collective efforts undertaken thus far (R.L.A. 1.0, 1986-1999).}, language = {en} } @phdthesis{Grimbs2009, author = {Grimbs, Sergio}, title = {Towards structure and dynamics of metabolic networks}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-32397}, school = {Universit{\"a}t Potsdam}, year = {2009}, abstract = {This work presents mathematical and computational approaches to cover various aspects of metabolic network modelling, especially regarding the limited availability of detailed kinetic knowledge on reaction rates. It is shown that precise mathematical formulations of problems are needed i) to find appropriate and, if possible, efficient algorithms to solve them, and ii) to determine the quality of the found approximate solutions. Furthermore, some means are introduced to gain insights on dynamic properties of metabolic networks either directly from the network structure or by additionally incorporating steady-state information. Finally, an approach to identify key reactions in a metabolic networks is introduced, which helps to develop simple yet useful kinetic models. The rise of novel techniques renders genome sequencing increasingly fast and cheap. In the near future, this will allow to analyze biological networks not only for species but also for individuals. Hence, automatic reconstruction of metabolic networks provides itself as a means for evaluating this huge amount of experimental data. A mathematical formulation as an optimization problem is presented, taking into account existing knowledge and experimental data as well as the probabilistic predictions of various bioinformatical methods. The reconstructed networks are optimized for having large connected components of high accuracy, hence avoiding fragmentation into small isolated subnetworks. The usefulness of this formalism is exemplified on the reconstruction of the sucrose biosynthesis pathway in Chlamydomonas reinhardtii. The problem is shown to be computationally demanding and therefore necessitates efficient approximation algorithms. The problem of minimal nutrient requirements for genome-scale metabolic networks is analyzed. Given a metabolic network and a set of target metabolites, the inverse scope problem has as it objective determining a minimal set of metabolites that have to be provided in order to produce the target metabolites. These target metabolites might stem from experimental measurements and therefore are known to be produced by the metabolic network under study, or are given as the desired end-products of a biotechological application. The inverse scope problem is shown to be computationally hard to solve. However, I assume that the complexity strongly depends on the number of directed cycles within the metabolic network. This might guide the development of efficient approximation algorithms. Assuming mass-action kinetics, chemical reaction network theory (CRNT) allows for eliciting conclusions about multistability directly from the structure of metabolic networks. Although CRNT is based on mass-action kinetics originally, it is shown how to incorporate further reaction schemes by emulating molecular enzyme mechanisms. CRNT is used to compare several models of the Calvin cycle, which differ in size and level of abstraction. Definite results are obtained for small models, but the available set of theorems and algorithms provided by CRNT can not be applied to larger models due to the computational limitations of the currently available implementations of the provided algorithms. Given the stoichiometry of a metabolic network together with steady-state fluxes and concentrations, structural kinetic modelling allows to analyze the dynamic behavior of the metabolic network, even if the explicit rate equations are not known. In particular, this sampling approach is used to study the stabilizing effects of allosteric regulation in a model of human erythrocytes. Furthermore, the reactions of that model can be ranked according to their impact on stability of the steady state. The most important reactions in that respect are identified as hexokinase, phosphofructokinase and pyruvate kinase, which are known to be highly regulated and almost irreversible. Kinetic modelling approaches using standard rate equations are compared and evaluated against reference models for erythrocytes and hepatocytes. The results from this simplified kinetic models can simulate acceptably the temporal behavior for small changes around a given steady state, but fail to capture important characteristics for larger changes. The aforementioned approach to rank reactions according to their influence on stability is used to identify a small number of key reactions. These reactions are modelled in detail, including knowledge about allosteric regulation, while all other reactions were still described by simplified reaction rates. These so-called hybrid models can capture the characteristics of the reference models significantly better than the simplified models alone. The resulting hybrid models might serve as a good starting point for kinetic modelling of genome-scale metabolic networks, as they provide reasonable results in the absence of experimental data, regarding, for instance, allosteric regulations, for a vast majority of enzymatic reactions.}, language = {en} } @phdthesis{Michalk2009, author = {Michalk, Daniel M.}, title = {An appraisal of a new method for the full-vector reconstruction of the Earth's magnetic field - applied to volcanic rocks from Mexico}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-31868}, school = {Universit{\"a}t Potsdam}, year = {2009}, abstract = {Das Magnetfeld der Erde wird durch Konvektionsstr{\"o}mungen im elektrisch leitf{\"a}higen, fl{\"u}ssigen eisenreichen {\"a}ußeren Erdkern erzeugt. Eine drastische Auspr{\"a}gung der dynamischen Prozesse im {\"a}ußeren Erdkern sind sowohl Polarit{\"a}tswechsel {\"u}ber geologische Zeitr{\"a}ume, als auch geomagnetische Feldexkursionen (kurze Umpolungen). Letztere sind in geologischen Archiven h{\"a}ufig unzureichend dokumentiert. F{\"u}r ein verbessertes Verst{\"a}ndnis {\"u}ber die Entwicklung des Erdmagnetfeldes in geologischer Vergangenheit ben{\"o}tigen wir Informationen {\"u}ber die Geometrie des gesamten Vektorfeldes, wof{\"u}r neben der Bestimmung der Feldrichtungen auch die Bestimmung der absoluten Pal{\"a}ointensit{\"a}t und des Alters notwendig ist. Insbesondere Vulkanite bieten die M{\"o}glichkeit, Daten {\"u}ber die Richtung und vor allem auch die Intensit{\"a}t des Erdmagnetfeldes zur Zeit ihrer Platznahme zu gewinnen. Bisweilen ist eine genaue Charakterisierung der Entwicklung des Erdmagnetfeldes in Zeit und Raum schwer m{\"o}glich, was sich in erster Linie auf den generellen Mangel an Pal{\"a}ointensit{\"a}tsdaten zur{\"u}ckf{\"u}hren l{\"a}sst. Ein Grund hierf{\"u}r ist, dass die meisten Methoden zur absoluten Pal{\"a}ointensit{\"a}tsbestimmung, auf Modifikationen der Thellier Methode basieren, welche nur auf magnetische Minerale im Einbereichs-Dom{\"a}nenzustand anwendbar ist und zudem hohe Ausschussraten liefert. Eine alternative Methode zur Bestimmung der absoluten Pal{\"a}ointensit{\"a}t ist die k{\"u}rzlich entwickelte „multispecimen parallel differential pTRM" (MS) Methode, welche im Vergleich zur Thellier Methode den Vorteil hat, dass sie theoretisch unabh{\"a}ngig ist vom Dom{\"a}nenzustand der magnetischen Minerale und somit auf alle Vulkanite anwendbar ist. Ein Schwerpunkt dieser Arbeit lag darauf, neue Informationen {\"u}ber das Auftreten und gegebenfalls die globale G{\"u}ltigkeit von geomagnetischen Feldexkursionen zu gewinnen. Hierf{\"u}r wurden etwa 75 Lavafl{\"u}sse des Transmexikanischen Vulkang{\"u}rtels f{\"u}r pal{\"a}omagnetische Studien beprobt. Eine Korrelation der mittleren Pal{\"a}orichtungen von 56 mexikanischen Laven mit einer um Feldexkursionen erg{\"a}nzten geomagnetischen Polarit{\"a}tszeitskala, lieferte Hinweise auf 4 Exkursionen. Ein bedeutendes Ergebnis dieser Arbeit sind ann{\"a}hrend komplett inversen Richtungen zweier Laven der Brunhes Chron. Dies gibt einen Hinweis darauf, dass diese Exkursionen kurze Zeitintervalle inverser Polarit{\"a}t mit globaler G{\"u}ltigkeit repr{\"a}sentieren k{\"o}nnten. Ein weiterer Schwerpunkt der vorliegenden Arbeit war, die neue MS Methode auf ihre Anwendbarkeit und Genauigkeit hin zu testen. Hierf{\"u}r wurden Pal{\"a}ointensit{\"a}tsexperimente an 11 historischen Laven aus Mexiko und Island durchgef{\"u}hrt. Ein Vergleich der Pal{\"a}ointensit{\"a}ten mit Daten von magnetischen Observatorien ergab, dass die MS Methode einen generellen Trend zur {\"U}bersch{\"a}tzung der Pal{\"a}ointensit{\"a}t aufweisst, welcher anhand von komplementierenden gesteinsmagnetischen Daten mit magnetischen Mineralen im Mehrbereichsteilchen-Zustand in Verbindung gebracht werden konnte. Diese Beobachtung liefert demnach einen ersten Beweis daf{\"u}r, dass die MS Methode m{\"o}glicherweise nicht wie urspr{\"u}nglich angenommen unabh{\"a}ngig vom Dom{\"a}nenzustand der Tr{\"a}germinerale ist. Im weiteren wurde eine Komplementierung der Richtungsdaten mexikanischer Laven durch absolute Pal{\"a}ointensit{\"a}tsbestimmungen angestrebt. Hierf{\"u}r wurde die MS Methode herangezogen und zum ersten Mal in großem Umfang auf Vulkanite mit Altern von bis zu 3,5 Millionen Jahre angewendet. Ein Vergleich mit Rekonstruktionen des Dipol-Momentes, welche auf den Daten der gegenw{\"a}rtigen globalen Pal{\"a}ointensit{\"a}tsdatanbasis basieren, ergaben, dass diese MS Daten mit hoher statistischer Wahrscheinlichkeit im Mittel etwa 30\% h{\"o}her sind. Die generell zu hohen Pal{\"a}onintensit{\"a}ten nach der MS Methode bekr{\"a}ftigen daher die Ergebnisse von historischen Laven dieser Arbeit, sowie anderer experimenteller Studien an synthetischen Proben, bei denen {\"U}bersch{\"a}tzungen von MS Pal{\"a}ointensit{\"a}ten von bis zu 30\% festgestellt wurden. Der Process, aus dem diese {\"U}bersch{\"a}tzung der Pal{\"a}ointensit{\"a}t resultiert ist eine Asymetrie des Entmagnetisierungs- und Remagnetisierungsprozesses heisst, dass ein effektives Entmagnetisieren w{\"a}hrend der Remagnetisierung im angelegten Laborfeld erfolgt. Diese Asymetrie scheint besonders bei pseudo-Einbereichsteilchen ausgepr{\"a}gt zu sein. Es wird allerdings davon ausgegangen, dass diese {\"U}bersch{\"a}tzung nicht gr{\"o}ßer ist, als was man bei einem Thellier Experiment an Proben mit {\"a}hnlicher magnetischer Korngr{\"o}ße erwarten w{\"u}rde.}, language = {en} } @phdthesis{Zamagni2009, author = {Zamagni, Jessica}, title = {Responses of a shallow-water ecosystem to the early Paleogene greenhouse environmental conditions : evolution of Larger Foraminifera and coral communities from the Northern Tethys}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-31853}, school = {Universit{\"a}t Potsdam}, year = {2009}, abstract = {Modern anthropogenic forcing of atmospheric chemistry poses the question of how the Earth System will respond as thousands of gigatons of greenhouse gas are rapidly added to the atmosphere. A similar, albeit nonanthropogenic, situation occurred during the early Paleogene, when catastrophic release of carbon to the atmosphere triggered abrupt increase in global temperatures. The best documented of these events is the Paleocene-Eocene Thermal Maximum (PETM, ~55 Ma) when the magnitude of carbon addition to the oceans and atmosphere was similar to those expected for the future. This event initiated global warming, changes in hydrological cycles, biotic extinction and migrations. A recently proposed hypothesis concerning changes in marine ecosystems suggests that this global warming strongly influenced the shallow-water biosphere, triggering extinctions and turnover in the Larger Foraminifera (LF) community and the demise of corals. The successions from the Adriatic Carbonate Platform (SW Slovenia) represent an ideal location to test the hypothesis of a possible causal link between the PETM and evolution of shallow-water organisms because they record continuous sedimentation from the Late Paleocene to the Early Eocene and are characterized by a rich biota, especially LF, fundamental for detailed biostratigraphic studies. In order to reconstruct paleoenvironmental conditions during deposition, I focused on sedimentological analysis and paleoecological study of benthic assemblages. During the Late Paleocene-earliest Eocene, sedimentation occurred on a shallow-water carbonate ramp system characterized by enhanced nutrient levels. LF represent the common constituent of the benthic assemblages that thrived in this setting throughout the Late Paleocene to the Early Eocene. With detailed biostratigraphic and chemostratigraphic analyses documenting the most complete record to date available for the PETM event in a shallow-water marine environment, I correlated chemostratigraphically for the first time the evolution of LF with the δ¹³C curves. This correlation demonstrated that no major turnover in the LF communities occurred synchronous with the PETM; thus the evolution of LF was mainly controlled by endogenous biotic forces. The study of Late Thanetian metric-sized microbialite-coral mounds which developed in the middle part of the ramp, documented the first Cenozoic occurrence of microbially-cemented mounds. The development of these mounds, with temporary dominance of microbial communities over corals, suggest environmentally-triggered "phase shifts" related to frequent fluctuations of nutrient/turbidity levels during recurrent wet phases which preceding the extreme greenhouse conditions of the PETM. The paleoecological study of the coral community in the microbialites-coral mounds, the study of corals from Early Eocene platform from SW France, and a critical, extensive literature research of Late Paleocene - Early Eocene coral occurrences from the Tethys, the Atlantic, the Caribbean realms suggested that these corals types, even if not forming extensive reefs, are common in the biofacies as small isolated colonies, piles of rubble or small patch-reefs. These corals might have developed 'alternative' life strategies to cope with harsh conditions (high/fluctuating nutrients/turbidity, extreme temperatures, perturbation of aragonite saturation state) during the greenhouse times of the early Paleogene, representing a good fossil analogue to modern corals thriving close to their thresholds for survival. These results demonstrate the complexity of the biological responses to extreme conditions, not only in terms of temperature but also nutrient supply, physical disturbance and their temporal variability and oscillating character.}, language = {en} } @phdthesis{ElSaadany2009, author = {El-Saadany, Mohamed Abdel Meged Marawan}, title = {Protective effect of dietary antioxidants and plant extracts on acute inflammation and hepatotoxicity in vitro}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-31585}, school = {Universit{\"a}t Potsdam}, year = {2009}, abstract = {Dietary antioxidants are believed to play an important role in the prevention and treatment of a variety of diseases associated with oxidative stress. Although there is a wide range of dietary antioxidants, the bulk of the research to date has been focused on the nutrient antioxidants vitamin C, E, and carotenoids. Certain relatively uncommon antioxidants such as lipoic acid (LA), and phenolic compounds such as (-)-epicatechin (EC), (-)-epigallocatechin (EGC), (-)-epicatechin gallate (ECG), and (-)-epigallocatechin gallate (EGCG), have not been extensively investigated although they may exert greater antioxidant potency than that of carotenoids and vitamins. Extracts from selected plants and plant byproducts may represent rich sources for one or more of such antioxidants and therefore exhibit higher effects than a single antioxidant due to the synergistic effects produced between such antioxidants. However, in the last decade a number of epidemiological, animal and in vitro studies have suggested a protective and therapeutic potency of these antioxidants in a broad range of diseases such as cancer, diabetes, atherosclerosis, cataract and acute and chronic neurological disorders. Inflammation, the response of the host toward any infection or injury, plays a central role in the development of many chronic diseases. Several evidences demonstrated the rise of different types of cancer from sites of inflammation. This suggests that active oxygen species and some cytokines generated in the inflamed tissues can cause injury to DNA and ultimately lead to carcinogenesis. Diethylnitrosamine (DEN) is one of the most important environmental carcinogens, present in a variety of foods, alcoholic beverages, tobacco smoke and it can be synthesized endogenously. In addition to the liver it can induce carcinogenesis in other organs like kidney, trachea, lung, esophagus, fore stomach, and nasal cavity. Several epidemiological and laboratory studies indicate that nitroso compounds including DEN may induce hyperplasia and chronic inflammation which is closely associated with the development of hepatocellular carcinoma. Despite increasing evidence on the potential of antioxidants in modulating the etiology of chronic diseases, little is known about their role in inflammation and acute phase response (APR). Therefore the aim of the present work was to study the protective effect of water and solvent extracts of eight plant and plant byproducts including green tea, artichoke, spinach, broccoli, onion and eggplant, orange and potato peels as well as eight antioxidants agents including EC, EGC, ECG, EGCG, ascorbic acid (AA), acetylcysteine (NAC), α-LA, and alpha-tocopherol (α-TOC) toward acute inflammation induced by interleukin-6 (IL-6) and hepatotoxicity induced by DEN in vitro. The negative acute phase proteins (APP), transthyretin (TTR) and retinol-binding protein (RBP) were used as inflammatory biomarkers analyzed by ELISA, whereas neutral red assay was used for evaluating the cytotoxicity. All experiments were performed in vitro using human hepatocarcinoma cell line (HepG2). Additionally the antioxidant activity was measured by TEAC and FRAP assays, phenolic content was measured by Folin-Ciocalteu and characterized by HPLC. Moreover, the microheterogeneity of TTR was detected using immunoprecipitation assay combined with SELDI-TOF MS. Results of present study showed that HepG2 cells provide a simple, sensitive in vitro system for studying the regulation of the negative APP, TTR and RBP under free and inflammatory condition. IL-6, a potent proinflammatory cytokine, in a concentration of 25 ng/ml was able to reduce TTR and RBP secretion by approximately 50-60\% after 24h of incubation. With exception of broccoli and water extract of onion which showed pro-inflammatory effects in this study, all other plant extracts, at specific concentrations, were able to elevate TTR secretion in normal condition and even under treatment of IL-6 where the effect was quite lower. Green tea followed by artichoke and potato peel exhibited the highest elevation in TTR concentration which reached 1.1 and 2.5 folds of control in presence and absences of IL-6 respectively. In general Plant extracts were ordered according their anti-inflammatory potency as following: in water extracts; green tea > artichoke > potato peel > orange peel > spinach > eggplant peel, where in solvent extracts; green tea > artichoke > potato peel > spinach > eggplant peel > onion > orange peel. The antiinflammatory effect of water extracts of green tea, artichoke and orange peel were significantly higher than their corresponding solvent extracts whereas water extracts of eggplant-, potato peels and spinach showed lower effect than their solvent extracts. On the other hand α-LA followed by EGCG and ECG exhibited the highest elevation in TTR concentration compared to other antioxidants. The relation between the anti-inflammatory potential and antioxidants activity and phenolic content for the investigated substances was generally weak. This may suggest the involvement of other mechanisms than antioxidants properties for the observed effect. TTR secreted by HepG2 cells has a molecular structure quite similar to the purified standard and serum TTR in which all the three main variants are contained including native, S-cystinylated and Sglutathionylated TTR. Interestingly, a variant with molecular mass of 13453.8 + 8.3 Da has been detected only in TTR secreted by HepG2. Among all investigated antioxidants and plant extracts, six substances were able to elevate the native preferable TTR variant. The potency of these substances can be ordered as following α-LA > NAC > onion > AA > EGCG > green tea. A weak correlation between elevation on TTR and shifting to the native form was observed. Similar weak correlation has also been observed between antioxidants activity and elevation in native TTR. Although DEN was able to induce cell death in a concentration dependent manner, it requires considerably higher concentrations for its effects especially after 24h. This may be attributed to a lack in cytochrome P450 enzymes produced by HepG2. At selected concentrations some antioxidants and plant extracts significantly attenuate DEN cytotoxicity as following: spinach > α-LA > artichoke > orange peel > eggplant peel > α-TOC > onion > AA. Contrary all other substances especially green tea, broccoli, potato peel, and ECG stimulate DEN toxicity. In conclusion, this study demonstrated that selected antioxidants and plant extracts may attenuate the inflammatory process, not only by their antioxidants potency but also by other mechanisms which remain unclear. They may also play a vital role on stabilizing the tetramic structure of TTR and thereby prevent amyloidosis diseases. Lipoic acid represents in this study unique function against inflammation and hepatotoxicity. Despite the protective effect demonstrated by investigated substances, attention should also be given to the pro-oxidant and potential cytotoxic effects produced at higher concentrations.}, language = {en} } @phdthesis{Durek2008, author = {Durek, Pawel}, title = {Comparative analysis of molecular interaction networks : the interplay between spatial and functional organizing principles}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-31439}, school = {Universit{\"a}t Potsdam}, year = {2008}, abstract = {The study of biological interaction networks is a central theme in systems biology. Here, we investigate common as well as differentiating principles of molecular interaction networks associated with different levels of molecular organization. They include metabolic pathway maps, protein-protein interaction networks as well as kinase interaction networks. First, we present an integrated analysis of metabolic pathway maps and protein-protein interaction networks (PIN). It has long been established that successive enzymatic steps are often catalyzed by physically interacting proteins forming permanent or transient multi-enzyme complexes. Inspecting high-throughput PIN data, it has been shown recently that, indeed, enzymes involved in successive reactions are generally more likely to interact than other protein pairs. In this study, we expanded this line of research to include comparisons of the respective underlying network topologies as well as to investigate whether the spatial organization of enzyme interactions correlates with metabolic efficiency. Analyzing yeast data, we detected long-range correlations between shortest paths between proteins in both network types suggesting a mutual correspondence of both network architectures. We discovered that the organizing principles of physical interactions between metabolic enzymes differ from the general PIN of all proteins. While physical interactions between proteins are generally dissortative, enzyme interactions were observed to be assortative. Thus, enzymes frequently interact with other enzymes of similar rather than different degree. Enzymes carrying high flux loads are more likely to physically interact than enzymes with lower metabolic throughput. In particular, enzymes associated with catabolic pathways as well as enzymes involved in the biosynthesis of complex molecules were found to exhibit high degrees of physical clustering. Single proteins were identified that connect major components of the cellular metabolism and hence might be essential for the structural integrity of several biosynthetic systems. Besides metabolic aspects of PINs, we investigated the characteristic topological properties of protein interactions involved in signaling and regulatory functions mediated by kinase interactions. Characteristic topological differences between PINs associated with metabolism, and those describing phosphorylation networks were revealed and shown to reflect the different modes of biological operation of both network types. The construction of phosphorylation networks is based on the identification of specific kinase-target relations including the determination of the actual phosphorylation sites (P-sites). The computational prediction of P-sites as well as the identification of involved kinases still suffers from insufficient accuracies and specificities of the underlying prediction algorithms, and the experimental identification in a genome-scale manner is not (yet) doable. Computational prediction methods have focused primarily on extracting predictive features from the local, one-dimensional sequence information surrounding P-sites. However the recognition of such motifs by the respective kinases is a spatial event. Therefore, we characterized the spatial distributions of amino acid residue types around P-sites and extracted signature 3D-profiles. We then tested the added value of spatial information on the prediction performance. When compared to sequence-only based predictors, a consistent performance gain was obtained. The availability of reliable training data of experimentally determined P-sites is critical for the development of computational prediction methods. As part of this thesis, we provide an assessment of false-positive rates of phosphoproteomic data.}, language = {en} } @phdthesis{Francke2009, author = {Francke, Till}, title = {Measurement and modelling of water and sediment fluxes in meso-scale dryland catchments}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-31525}, school = {Universit{\"a}t Potsdam}, year = {2009}, abstract = {Water shortage is a serious threat for many societies worldwide. In drylands, water management measures like the construction of reservoirs are affected by eroded sediments transported in the rivers. Thus, the capability of assessing water and sediment fluxes at the river basin scale is of vital importance to support management decisions and policy making. This subject was addressed by the DFG-funded SESAM-project (Sediment Export from large Semi-Arid catchments: Measurements and Modelling). As a part of this project, this thesis focuses on (1) the development and implementation of an erosion module for a meso-scale catchment model, (2) the development of upscaling and generalization methods for the parameterization of such model, (3) the execution of measurements to obtain data required for the modelling and (4) the application of the model to different study areas and its evaluation. The research was carried out in two meso-scale dryland catchments in NE-Spain: Ribera Salada (200 km²) and Is{\´a}bena (450 km²). Adressing objective 1, WASA-SED, a spatially semi-distributed model for water and sediment transport at the meso-scale was developed. The model simulates runoff and erosion processes at the hillslope scale, transport processes of suspended and bedload fluxes in the river reaches, and retention and remobilisation processes of sediments in reservoirs. This thesis introduces the model concept, presents current model applications and discusses its capabilities and limitations. Modelling at larger scales faces the dilemma of describing relevant processes while maintaining a manageable demand for input data and computation time. WASA-SED addresses this challenge by employing an innovative catena-based upscaling approach: the landscape is represented by characteristic toposequences. For deriving these toposequences with regard to multiple attributes (eg. topography, soils, vegetation) the LUMP-algorithm (Landscape Unit Mapping Program) was developed and related to objective 2. It incorporates an algorithm to retrieve representative catenas and their attributes, based on a Digital Elevation Model and supplemental spatial data. These catenas are classified to provide the discretization for the WASA-SED model. For objective 3, water and sediment fluxes were monitored at the catchment outlet of the Is{\´a}bena and some of its sub-catchments. For sediment yield estimation, the intermittent measurements of suspended sediment concentration (SSC) had to be interpolated. This thesis presents a comparison of traditional sediment rating curves (SRCs), generalized linear models (GLMs) and non-parametric regression using Random Forests (RF) and Quantile Regression Forests (QRF). The observed SSCs are highly variable and range over six orders of magnitude. For these data, traditional SRCs performed poorly, as did GLMs, despite including other relevant process variables (e.g. rainfall intensities, discharge characteristics). RF and QRF proved to be very robust and performed favourably for reproducing sediment dynamics. QRF additionally excels in providing estimates on the accuracy of the predictions. Subsequent analysis showed that most of the sediment was exported during intense storms of late summer. Later floods yielded successively less sediment. Comparing sediment generation to yield at the outlet suggested considerable storage effects within the river channel. Addressing objective 4, the WASA-SED model was parameterized for the two study areas in NE Spain and applied with different foci. For Ribera Salada, the uncalibrated model yielded reasonable results for runoff and sediment. It provided quantitative measures of the change in runoff and sediment yield for different land-uses. Additional land management scenarios were presented and compared to impacts caused by climate change projections. In contrast, the application for the Is{\´a}bena focussed on exploring the full potential of the model's predictive capabilities. The calibrated model achieved an acceptable performance for the validation period in terms of water and sediment fluxes. The inadequate representation of the lower sub-catchments inflicted considerable reductions on model performance, while results for the headwater catchments showed good agreement despite stark contrasts in sediment yield. In summary, the application of WASA-SED to three catchments proved the model framework to be a practicable multi-scale approach. It successfully links the hillslope to the catchment scale and integrates the three components hillslope, river and reservoir in one model. Thus, it provides a feasible approach for tackling issues of water and sediment yield at the meso-scale. The crucial role of processes like transmission losses and sediment storage in the river has been identified. Further advances can be expected when the representation of connectivity of water and sediment fluxes (intra-hillslope, hillslope-river, intra-river) is refined and input data improves.}, language = {en} } @inproceedings{OPUS4-2990, title = {Optimality theory and minimalism : interface theories}, editor = {Broekhuis, Hans and Vogel, Ralf}, publisher = {Universit{\"a}tsverlag Potsdam}, address = {Potsdam}, isbn = {978-3-940793-61-4}, issn = {1616-7392 print}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-27577}, pages = {212}, year = {2009}, abstract = {The papers contained in this issue share the insight that the different components of the grammar sometimes impose conflicting requirements on the grammar's output, and that, in order to handle such conflicts, it seems advantageous to combine aspects from minimalist and OT modelling. The papers show that this can be undertaken in a multiplicity of ways, by using varying proportions of each framework, and offer a broad range of perspectives for future research.}, language = {en} } @book{BeckerGieseNeumann2009, author = {Becker, Basil and Giese, Holger and Neumann, Stefan}, title = {Correct dynamic service-oriented architectures : modeling and compositional verification with dynamic collaborations}, organization = {System Analysis and Modeling Group}, isbn = {978-3-940793-91-1}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-30473}, publisher = {Universit{\"a}t Potsdam}, year = {2009}, abstract = {Service-oriented modeling employs collaborations to capture the coordination of multiple roles in form of service contracts. In case of dynamic collaborations the roles may join and leave the collaboration at runtime and therefore complex structural dynamics can result, which makes it very hard to ensure their correct and safe operation. We present in this paper our approach for modeling and verifying such dynamic collaborations. Modeling is supported using a well-defined subset of UML class diagrams, behavioral rules for the structural dynamics, and UML state machines for the role behavior. To be also able to verify the resulting service-oriented systems, we extended our former results for the automated verification of systems with structural dynamics [7, 8] and developed a compositional reasoning scheme, which enables the reuse of verification results. We outline our approach using the example of autonomous vehicles that use such dynamic collaborations via ad-hoc networking to coordinate and optimize their joint behavior.}, language = {en} } @misc{Mulansky2009, type = {Master Thesis}, author = {Mulansky, Mario}, title = {Localization properties of nonlinear disordered lattices}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-31469}, school = {Universit{\"a}t Potsdam}, year = {2009}, abstract = {In this thesis, the properties of nonlinear disordered one dimensional lattices is investigated. Part I gives an introduction to the phenomenon of Anderson Localization, the Discrete Nonlinear Schroedinger Equation and its properties as well as the generalization of this model by introducing the nonlinear index α. In Part II, the spreading behavior of initially localized states in large, disordered chains due to nonlinearity is studied. Therefore, different methods to measure localization are discussed and the structural entropy as a measure for the peak structure of probability distributions is introduced. Finally, the spreading exponent for several nonlinear indices is determined numerically and compared with analytical approximations. Part III deals with the thermalization in short disordered chains. First, the term thermalization and its application to the system in use is explained. Then, results of numerical simulations on this topic are presented where the focus lies especially on the energy dependence of the thermalization properties. A connection with so-called breathers is drawn.}, language = {en} } @phdthesis{Fritz2008, author = {Fritz, Thomas}, title = {Emotion investigated with music of variable valence : neurophysiology and cultural influence}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-29114}, school = {Universit{\"a}t Potsdam}, year = {2008}, abstract = {Music is a powerful and reliable means to stimulate the percept of both intense pleasantness and unpleasantness in the perceiver. However, everyone's social experiences with music suggest that the same music piece may elicit a very different valence percept in different individuals. A comparison of music from different historical periods suggests that enculturation modulates the valence percept of intervals and harmonies, and thus possibly also of relatively basic feature extraction processes. Strikingly, it is still largely unknown how much the valence percept is dependent on physical properties of the stimulus and thus mediated by a universal perceptual mechanism, and how much it is dependent on cultural imprinting. The current thesis investigates the neurophysiology of the valence percept, and the modulating influence of culture on several distinguishable sub-processes of music processing, so-called functional modules of music processing, engaged in the mediation of the valence percept.}, language = {en} } @phdthesis{Lahti2007, author = {Lahti, Makreeta}, title = {Security cooperation as a way to stop the spread of nuclear weapons? : Nuclear nonproliferation policies of the United States towards the Federal Republic of Germany and Israel, 1945-1968}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-31459}, school = {Universit{\"a}t Potsdam}, year = {2007}, abstract = {In my dissertation on 'Security Cooperation as a Way to Stop the Spread of Nu-clear Weapons? Nuclear Nonproliferation Policies of the United States towards the Federal Republic of Germany and Israel, 1945-1968', I study the use of security assistance as nonproliferation policy. I use insights of the Structural Realist and the Rational Institutionalist theories of International Relations to explain, respectively, important foreign policy goals and the basic orientation of policies, on the one hand, and the practical workings and effects of security cooperation on states' behavior, on the other hand. Moreover, I consider the relations of the United States (US) with the two states in light of bargaining theory to explain the level of US ability to press other states to its preferred courses of action. The study is thus a combination of theory proposing and testing and historic description and explanation. It is also policy-relevant as I seek general lessons regarding the use of security cooperation as nonproliferation policy. I show that the US sought to keep the Federal Republic of Germany (FRG) from acquiring nuclear weapons in order to avoid crises with Moscow and threats to the cohesion of NATO. But the US also saw it as necessary to credibly guarantee the security of the FRG and treat it well in order to ensure that it would remain satisfied as an ally and without own nuclear weapons. Through various institutionalized security cooperation schemes, the US succeeded in this - though the FRG did acquire an option to produce nuclear weapons. The US opposed Israel's nuclear weapon ambitions in turn because of an expectation that Arab states' reactions could otherwise result in greater tension and risks of escalation and a worse balance-of-power in the area. But as also a US-Israel alliance could have led to stronger Arab-Soviet ties and thus a worse balance-of-power, and as it was not in US in-terest to be tied to Israel's side in all regional issues, the US was not prepared to guarantee Israel's security in a formal, credible way like it did in West Germany's case. The US failed to persuade Israel to forgo producing nuclear weapons but gradually, an opaque nu-clear status combined with US arms sales that helped Israel to maintain a conventional military advantage over Arabs emerged as a solution to Israel's security strategy. Because of perceptions that Israel and the FRG had also other options than cooperation with the US, and because the US ability to punish them for unwanted action was limited, these states were able to offer resistance when the US pressed its nonproliferation stance on them.}, language = {en} } @phdthesis{Frey2009, author = {Frey, Simone K.}, title = {Investigations on extra- and intracellular retinol-binding proteins}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-31428}, school = {Universit{\"a}t Potsdam}, year = {2009}, abstract = {The fat-soluble vitamin A, which is chemically referred to retinol (ROH), is known to be essential for the process of vision, the immune system but also for cell differentiation and proliferation. Recently, ROH itself has been reported to be involved in adipogenesis and a ROH transport protein, the retinol-binding protein 4 (RBP4), in insulin resistance and type 2 diabetes. However, there is still considerable scientific debate about this relation. With the increasing amount of studies investigating the relation of ROH in obesity and type 2 diabetes, basic research is an essential prerequisite for interpreting these results. This thesis enhances the knowledge on this relation by reviewing ROH metabolism on extra- and intracellular level. Aim 1: In the blood stream ROH is transported in a complex with RBP4 and a second protein, transthyretin (TTR), to the target cells. The levels of RBP4 and TTR are influenced by several factors but mainly by liver and kidney function. The reason for that is that liver and the kidneys are the sites of RBP4 synthesis and catabolism, respectively. Interestingly, obesity and type 2 diabetes involve disorders of the liver and the kidneys. Therefore the aim was to investigate factors that influence RBP4 and TTR levels in relation to obesity and type 2 diabetes (Part 1). Aim 2: Once arrived in the target cell ROH is bound to cellular retinol-binding protein type I (CRBP-I) and metabolised: ROH can either be stored as retinylesters or it can be oxidised to retinoic acid (RA). By acting as a transcription factor in the nucleus RA may influence processes such as adipogenesis. Therefore vitamin A has been postulated to be involved in obesity and type 2 diabetes. CRBP-I is known to mediate the storage of ROH in the liver, but the extra-hepatic metabolism and the functions of CRBP-I are not well known. This has been investigated in Part 2 of this work. Material \& Methods: RBP4 and TTR levels were investigated by ELISA in serum samples of human subjects with overweight, type 2 diabetes, kidney or liver dysfunction. Molecular alterations of the RBP4 and TTR protein structure were analysed by MALDI-TOF mass spectrometry. The functions of intracellular CRBP-I were investigated in CRBP-I knock-out mice in liver and extra-hepatic tissues by measuring ROH levels as well as the levels of its storage form, the retinylesters, using reverse phase HPLC. The postprandial uptake of ROH into tissues was analysed using labelled ROH. The mRNA levels of enzymes that metabolize ROH were examined by real-time polymerase chain reaction (RCR). Results: The previous published results showing increased RBP4 levels in type 2 diabetic patients could not be confirmed in this work. However, it could be shown that during kidney dysfunction RBP4 levels are increased and that RBP4 and TTR levels are decreased during liver dysfunction. The important new finding of this work is that increased RBP4 levels in type 2 diabetic mice were increased when kidney function was decreased. Thus an increase in RBP4 levels in type 2 diabetes may be the effect of a reduced kidney function which is common in type 2 diabetes. Interestingly, during severe kidney dysfunction the molecular structure of RBP4 and TTR was altered in a specific manner which was not the case during liver diseases and type 2 diabetes. This underlines the important function of the kidneys in RBP4 metabolism. CRBP-I has been confirmed to be responsible for the ROH storage in the liver since CRBP-I knock-out mice had decreased ROH and retinylesters (the storage form of ROH) levels in the liver. Interestingly, in the adipose tissue (the second largest ROH storage tissue in the body) ROH and retinylesters levels were higher in the CRBP-I knock-out compared to the wild-type mice. It could be shown in this work that a different ROH binding protein, cellular retinol-binding protein type III, is upregulated in CRBP-I knock-out mice. Moreover enzymes were identified which mediate very efficiently ROH esterification in the adipose tissue of the knock-out mice. In the pancreas there was a higher postprandial ROH uptake in the CRBP-I knock-out compard to wild-type mice. Even under a vitamin A deficient diet the knock-out animals had ROH and retinylesters levels which were comparable to wild-type animals. These results underline the important role of ROH for insulin secretion in the pancreas. Summing up, there is evidence that RBP4 levels are more determined by kidney function than by type 2 diabetes and that specific molecular modifications occur during kidney dysfunction. The results in adipose tissue and pancreas of CRBP-I knock-out mice support the hypothesis that ROH plays an important role in glucose and lipid metabolism.}, language = {en} } @phdthesis{Skrabania2008, author = {Skrabania, Katja}, title = {The multifarious self-assembly of triblock copolymers : from multi-responsive polymers and multi-compartment micelles}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-30764}, school = {Universit{\"a}t Potsdam}, year = {2008}, abstract = {New ABC triblock copolymers were synthesized by controlled free-radical polymerization via Reversible Addition-Fragmentation chain Transfer (RAFT). Compared to amphiphilic diblock copolymers, the prepared materials formed more complex self-assembled structures in water due to three different functional units. Two strategies were followed: The first approach relied on double-thermoresponsive triblock copolymers exhibiting Lower Critical Solution Temperature (LCST) behavior in water. While the first phase transition triggers the self-assembly of triblock copolymers upon heating, the second one allows to modify the self-assembled state. The stepwise self-assembly was followed by turbidimetry, dynamic light scattering (DLS) and 1H NMR spectroscopy as these methods reflect the behavior on the macroscopic, mesoscopic and molecular scale. Although the first phase transition could be easily monitored due to the onset of self-assembly, it was difficult to identify the second phase transition unambiguously as the changes are either marginal or coincide with the slow response of the self-assembled system to relatively fast changes of temperature. The second approach towards advanced polymeric micelles exploited the thermodynamic incompatibility of "triphilic" block copolymers - namely polymers bearing a hydrophilic, a lipophilic and a fluorophilic block - as the driving force for self-assembly in water. The self-assembly of these polymers in water produced polymeric micelles comprising a hydrophilic corona and a microphase-separated micellar core with lipophilic and fluorophilic domains - so called multi-compartment micelles. The association of triblock copolymers in water was studied by 1H NMR spectroscopy, DLS and cryogenic transmission electron microscopy (cryo-TEM). Direct imaging of the polymeric micelles in solution by cryo-TEM revealed different morphologies depending on the block sequence and the preparation conditions. While polymers with the sequence hydrophilic-lipophilic-fluorophilic built core-shell-corona micelles with the core being the fluorinated compartment, block copolymers with the hydrophilic block in the middle formed spherical micelles where single or multiple fluorinated domains "float" as disks on the surface of the lipophilic core. Increasing the temperature during micelle preparation or annealing of the aqueous solutions after preparation at higher temperatures induced occasionally a change of the micelle morphology or the particle size distribution. By RAFT polymerization not only the desired polymeric architectures could be realized, but the technique provided in addition a precious tool for molar mass characterization. The thiocarbonylthio moieties, which are present at the chain ends of polymers prepared by RAFT, absorb light in the UV and visible range and were employed for end-group analysis by UV-vis spectroscopy. A variety of dithiobenzoate and trithiocarbonate RAFT agents with differently substituted initiating R groups were synthesized. The investigation of their absorption characteristics showed that the intensity of the absorptions depends sensitively on the substitution pattern next to the thiocarbonylthio moiety and on the solvent polarity. According to these results, the conditions for a reliable and convenient end-group analysis by UV-vis spectroscopy were optimized. As end-group analysis by UV-vis spectroscopy is insensitive to the potential association of polymers in solution, it was advantageously exploited for the molar mass characterization of the prepared amphiphilic block copolymers.}, language = {en} } @book{RolfesSteinbrinkUhl2009, author = {Rolfes, Manfred and Steinbrink, Malte and Uhl, Christina}, title = {Townships as attraction : an empirical study of township tourism in Cape Town}, publisher = {Universit{\"a}tsverlag Potsdam}, address = {Potsdam}, isbn = {978-3-940793-79-9}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-28947}, publisher = {Universit{\"a}t Potsdam}, pages = {60}, year = {2009}, abstract = {Since the end of the Apartheid international tourism in South Africa has increasingly gained importance for the national economy. The centre of this PKS issue's attention is a particular form of tourism: Township tourism, i.e. guided tours to the residential areas of the black population. About 300,000 tourists per year visit the townships of Cape Town. The tours are also called Cultural, Social, or Reality Tours. The different aspects of township tourism in Cape Town were subject of a geographic field study, which was undertaken during a student research project of Potsdam University in 2007. The text at hand presents the empirical results of the field study, and demonstrates how townships are constructed as spaces of tourism.}, language = {en} } @book{GieseHildebrandt2009, author = {Giese, Holger and Hildebrandt, Stephan}, title = {Efficient model synchronization of large-scale models}, publisher = {Universit{\"a}tsverlag Potsdam}, address = {Potsdam}, isbn = {978-3-940793-84-3}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-29281}, publisher = {Universit{\"a}t Potsdam}, pages = {27}, year = {2009}, abstract = {Model-driven software development requires techniques to consistently propagate modifications between different related models to realize its full potential. For large-scale models, efficiency is essential in this respect. In this paper, we present an improved model synchronization algorithm based on triple graph grammars that is highly efficient and, therefore, can also synchronize large-scale models sufficiently fast. We can show, that the overall algorithm has optimal complexity if it is dominating the rule matching and further present extensive measurements that show the efficiency of the presented model transformation and synchronization technique.}, language = {en} } @unpublished{LyTarkhanov2007, author = {Ly, I. and Tarkhanov, Nikolai Nikolaevich}, title = {The cauchy problem for nonlinear elliptic equations}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-30228}, year = {2007}, abstract = {This paper is devoted to investigation of the Cauchy problem for nonlinear elliptic equations with a small parameter.}, language = {en} } @phdthesis{Koehler2009, author = {K{\"o}hler, Andreas}, title = {Recognition and investigation of temporal patterns in seismic wavefields using unsupervised learning techniques}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-29702}, school = {Universit{\"a}t Potsdam}, year = {2009}, abstract = {Modern acquisition of seismic data on receiver networks worldwide produces an increasing amount of continuous wavefield recordings. Hence, in addition to manual data inspection, seismogram interpretation requires new processing utilities for event detection, signal classification and data visualization. Various machine learning algorithms, which can be adapted to seismological problems, have been suggested in the field of pattern recognition. This can be done either by means of supervised learning using manually defined training data or by unsupervised clustering and visualization. The latter allows the recognition of wavefield patterns, such as short-term transients and long-term variations, with a minimum of domain knowledge. Besides classical earthquake seismology, investigations of temporal patterns in seismic data also concern novel approaches such as noise cross-correlation or ambient seismic vibration analysis in general, which have moved into focus within the last decade. In order to find records suitable for the respective approach or simply for quality control, unsupervised preprocessing becomes important and valuable for large data sets. Machine learning techniques require the parametrization of the data using feature vectors. Applied to seismic recordings, wavefield properties have to be computed from the raw seismograms. For an unsupervised approach, all potential wavefield features have to be considered to reduce subjectivity to a minimum. Furthermore, automatic dimensionality reduction, i.e. feature selection, is required in order to decrease computational cost, enhance interpretability and improve discriminative power. This study presents an unsupervised feature selection and learning approach for the discovery, imaging and interpretation of significant temporal patterns in seismic single-station or network recordings. In particular, techniques permitting an intuitive, quickly interpretable and concise overview of available records are suggested. For this purpose, the data is parametrized by real-valued feature vectors for short time windows using standard seismic analysis tools as feature generation methods, such as frequency-wavenumber, polarization, and spectral analysis. The choice of the time window length is dependent on the expected durations of patterns to be recognized or discriminated. We use Self-Organizing Maps (SOMs) for a data-driven feature selection, visualization and clustering procedure, which is particularly suitable for high-dimensional data sets. Using synthetics composed of Rayleigh and Love waves and three different types of real-world data sets, we show the robustness and reliability of our unsupervised learning approach with respect to the effect of algorithm parameters and data set properties. Furthermore, we approve the capability of the clustering and imaging techniques. For all data, we find improved discriminative power of our feature selection procedure compared to feature subsets manually selected from individual wavefield parametrization methods. In particular, enhanced performance is observed compared to the most favorable individual feature generation method, which is found to be the frequency spectrum. The method is applied to regional earthquake records at the European Broadband Network with the aim to define suitable features for earthquake detection and seismic phase classification. For the latter, we find that a combination of spectral and polarization features favor S wave detection at a single receiver. However, SOM-based visualization of phase discrimination shows that clustering applied to the records of two stations only allows onset or P wave detection, respectively. In order to improve the discrimination of S waves on receiver networks, we recommend to consider additionally the temporal context of feature vectors. The application to continuous recordings of seismicity close to an active volcano (Mount Merapi, Java, Indonesia) shows that two typical volcano-seismic events (VTB and Guguran) can be detected and distinguished by clustering. In contrast, so-called MP events cannot be discriminated. Comparable results are obtained for selected features and recognition rates regarding a previously implemented supervised classification system. Finally, we test the reliability of wavefield clustering to improve common ambient vibration analysis methods such as estimation of dispersion curves and horizontal to vertical spectral ratios. It is found, that in general, the identified short- and long-term patterns have no significant impact on those estimates. However, for individual sites, effects of local sources can be identified. Leaving out the corresponding clusters, yields reduced uncertainties or allows for improving estimation of dispersion curves.}, language = {en} } @unpublished{CalvoSchulze2005, author = {Calvo, D. and Schulze, Bert-Wolfgang}, title = {Edge symbolic structures of second generation}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-29940}, year = {2005}, abstract = {Operators on a manifold with (geometric) singularities are degenerate in a natural way. They have a principal symbolic structure with contributions from the different strata of the configuration. We study the calculus of such operators on the level of edge symbols of second generation, based on specific quantizations of the corner-degenerate interior symbols, and show that this structure is preserved under compositions.}, language = {en} } @book{OPUS4-2806, title = {Armenia : a human rights perspective for peace and democracy; human rights, human rights education and minorities}, editor = {Mihr, Anja and Mkrtichyan, Artur and Mahler, Claudia and Toivanen, Reetta}, isbn = {978-3-937786-66-7}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-29740}, publisher = {Universit{\"a}t Potsdam}, year = {2005}, abstract = {I. Human Rights and Democratic Movements in Armenia - Human Rights as an "Attractor" of Europeanization Processes of Transcaucasian "Neither War nor Peace Societies" (Artur Mkrtichyan) - Human Rights Defender's Office Armenia (Larisa Alaverdyan) - The Factor of Human Rights Protection as Criteria for the Development in the Social System (Hovhannes Hovhannisyan) - Two Priorities and Two Suggestions in Leading the Way to Human Rights Protection (Gevork Manoukian) - Intrastate Mechanisms of the Protection of Human Political Rights and Freedoms in Armenia (Ashot A. Alexanyan) - The Future of Democracy in Armenia: Institutional and Mass Beliefs Perspectives (Alexander Markarov) II. Human Rights and Education in Armenia - Human Rights in the System of Civic Education Values (Valery Poghosyan) - The Role of Academic Knowledge in Maintaining Tolerance (Ani Muradyan) - Rights of a Child or Duties of Adults...? (Mira Antonyan) - The Right to Education for Children with Special Needs: Inclusive Education in Armenia (Marina Hovhannissyan) - Human Rights Awareness and UNDP Evaluation in Armenia (Kristina Henschen) - Human Rights Education in Armenia - A Base Line Study (Litit Umroyan; Lucig Danielian) III. Human Rights and Minorities in Armenia - Human Rights, Minorities and Human Rights Education in Armenia: An External Perspective (Claudia Mahler; Anja Mihr; Reetta Toivanen) - Minorities and Identity in Armenia (Tatevik Margaryan) - Legal and Real Opportunities for the National Minorities Residing on the Territory of the Republic of Armenia (Hranush Kharatyan)}, language = {en} } @phdthesis{Mergenthaler2009, author = {Mergenthaler, Konstantin K.}, title = {The control of fixational eye movements}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-29397}, school = {Universit{\"a}t Potsdam}, year = {2009}, abstract = {In normal everyday viewing, we perform large eye movements (saccades) and miniature or fixational eye movements. Most of our visual perception occurs while we are fixating. However, our eyes are perpetually in motion. Properties of these fixational eye movements, which are partly controlled by the brainstem, change depending on the task and the visual conditions. Currently, fixational eye movements are poorly understood because they serve the two contradictory functions of gaze stabilization and counteraction of retinal fatigue. In this dissertation, we investigate the spatial and temporal properties of time series of eye position acquired from participants staring at a tiny fixation dot or at a completely dark screen (with the instruction to fixate a remembered stimulus); these time series were acquired with high spatial and temporal resolution. First, we suggest an advanced algorithm to separate the slow phases (named drift) and fast phases (named microsaccades) of these movements, which are considered to play different roles in perception. On the basis of this identification, we investigate and compare the temporal scaling properties of the complete time series and those time series where the microsaccades are removed. For the time series obtained during fixations on a stimulus, we were able to show that they deviate from Brownian motion. On short time scales, eye movements are governed by persistent behavior and on a longer time scales, by anti-persistent behavior. The crossover point between these two regimes remains unchanged by the removal of microsaccades but is different in the horizontal and the vertical components of the eyes. Other analyses target the properties of the microsaccades, e.g., the rate and amplitude distributions, and we investigate, whether microsaccades are triggered dynamically, as a result of earlier events in the drift, or completely randomly. The results obtained from using a simple box-count measure contradict the hypothesis of a purely random generation of microsaccades (Poisson process). Second, we set up a model for the slow part of the fixational eye movements. The model is based on a delayed random walk approach within the velocity related equation, which allows us to use the data to determine control loop durations; these durations appear to be different for the vertical and horizontal components of the eye movements. The model is also motivated by the known physiological representation of saccade generation; the difference between horizontal and vertical components concurs with the spatially separated representation of saccade generating regions. Furthermore, the control loop durations in the model suggest an external feedback loop for the horizontal but not for the vertical component, which is consistent with the fact that an internal feedback loop in the neurophysiology has only been identified for the vertical component. Finally, we confirmed the scaling properties of the model by semi-analytical calculations. In conclusion, we were able to identify several properties of the different parts of fixational eye movements and propose a model approach that is in accordance with the described neurophysiology and described limitations of fixational eye movement control.}, language = {en} } @book{OPUS4-2793, title = {Proceedings of the 3rd Ph.D. Retreat of the HPI Research School on Service-oriented Systems Engineering}, editor = {Meinel, Christoph and Plattner, Hasso and D{\"o}llner, J{\"u}rgen Roland Friedrich and Weske, Mathias and Polze, Andreas and Hirschfeld, Robert and Naumann, Felix and Giese, Holger}, publisher = {Universit{\"a}tsverlag Potsdam}, address = {Potsdam}, isbn = {978-3-940793-81-2}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-29148}, publisher = {Universit{\"a}t Potsdam}, pages = {Getr. Z{\"a}hlung}, year = {2009}, abstract = {Design and Implementation of service-oriented architectures imposes a huge number of research questions from the fields of software engineering, system analysis and modeling, adaptability, and application integration. Component orientation and web services are two approaches for design and realization of complex web-based system. Both approaches allow for dynamic application adaptation as well as integration of enterprise application. Commonly used technologies, such as J2EE and .NET, form de facto standards for the realization of complex distributed systems. Evolution of component systems has lead to web services and service-based architectures. This has been manifested in a multitude of industry standards and initiatives such as XML, WSDL UDDI, SOAP, etc. All these achievements lead to a new and promising paradigm in IT systems engineering which proposes to design complex software solutions as collaboration of contractually defined software services. Service-Oriented Systems Engineering represents a symbiosis of best practices in object-orientation, component-based development, distributed computing, and business process management. It provides integration of business and IT concerns. The annual Ph.D. Retreat of the Research School provides each member the opportunity to present his/her current state of their research and to give an outline of a prospective Ph.D. thesis. Due to the interdisciplinary structure of the Research Scholl, this technical report covers a wide range of research topics. These include but are not limited to: Self-Adaptive Service-Oriented Systems, Operating System Support for Service-Oriented Systems, Architecture and Modeling of Service-Oriented Systems, Adaptive Process Management, Services Composition and Workflow Planning, Security Engineering of Service-Based IT Systems, Quantitative Analysis and Optimization of Service-Oriented Systems, Service-Oriented Systems in 3D Computer Graphics, as well as Service-Oriented Geoinformatics.}, language = {en} } @book{Iro2009, author = {Iro, Andrea}, title = {The UN Peacebuilding Commission : lessons from Sierra Leone}, publisher = {Universit{\"a}tsverlag Potsdam}, address = {Potsdam}, isbn = {978-3-940793-77-5}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-29599}, publisher = {Universit{\"a}t Potsdam}, pages = {109}, year = {2009}, abstract = {"The UN Peacebuilding Commission - Lessons from Sierra Leone" by political scientist Andrea Iro is an assessment of the United Nations Peacebuilding Commission (PBC) and the United Nations Peacebuilding Fund (PBF) by analysing their performance over the last two years in Sierra Leone, one of the first PBC focus countries. The paper explores the key question of how the PBC/PBF's mandate has been translated into operational practice in the field. It concludes that though the overall impact has been mainly positive and welcomed by the country, translating the general mandate into concrete activities remains a real challenge at the country level.}, language = {en} } @phdthesis{Oenel2008, author = {{\"O}nel, Hakan}, title = {Electron acceleration in a flare plasma via coronal circuits}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-29035}, school = {Universit{\"a}t Potsdam}, year = {2008}, abstract = {The Sun is a star, which due to its proximity has a tremendous influence on Earth. Since its very first days mankind tried to "understand the Sun", and especially in the 20th century science has uncovered many of the Sun's secrets by using high resolution observations and describing the Sun by means of models. As an active star the Sun's activity, as expressed in its magnetic cycle, is closely related to the sunspot numbers. Flares play a special role, because they release large energies on very short time scales. They are correlated with enhanced electromagnetic emissions all over the spectrum. Furthermore, flares are sources of energetic particles. Hard X-ray observations (e.g., by NASA's RHESSI spacecraft) reveal that a large fraction of the energy released during a flare is transferred into the kinetic energy of electrons. However the mechanism that accelerates a large number of electrons to high energies (beyond 20 keV) within fractions of a second is not understood yet. The thesis at hand presents a model for the generation of energetic electrons during flares that explains the electron acceleration based on real parameters obtained by real ground and space based observations. According to this model photospheric plasma flows build up electric potentials in the active regions in the photosphere. Usually these electric potentials are associated with electric currents closed within the photosphere. However as a result of magnetic reconnection, a magnetic connection between the regions of different magnetic polarity on the photosphere can establish through the corona. Due to the significantly higher electric conductivity in the corona, the photospheric electric power supply can be closed via the corona. Subsequently a high electric current is formed, which leads to the generation of hard X-ray radiation in the dense chromosphere. The previously described idea is modelled and investigated by means of electric circuits. For this the microscopic plasma parameters, the magnetic field geometry and hard X-ray observations are used to obtain parameters for modelling macroscopic electric components, such as electric resistors, which are connected with each other. This model demonstrates that such a coronal electric current is correlated with large scale electric fields, which can accelerate the electrons quickly up to relativistic energies. The results of these calculations are encouraging. The electron fluxes predicted by the model are in agreement with the electron fluxes deduced from the measured photon fluxes. Additionally the model developed in this thesis proposes a new way to understand the observed double footpoint hard X-ray sources.}, language = {en} } @phdthesis{Parra2008, author = {Parra, Mauricio}, title = {Cenozoic foreland-basin evolution in the northern Andes : insights from thermochronology and basin analysis in the Eastern Cordillera, Colombia}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-29333}, school = {Universit{\"a}t Potsdam}, year = {2008}, abstract = {The modern foreland basin straddling the eastern margin of the Andean orogen is the prime example of a retro-arc foreland basin system adjacent to a subduction orogen. While widely studied in the central and southern Andes, the spatial and temporal evolution of the Cenozoic foreland basin system in the northern Andes has received considerably less attention. This is in part due to the complex geodynamic boundary conditions, such as the oblique subduction and accretion of the Caribbean plates to the already complex interaction between the Nazca and the South American plates. In the Colombian Andes, for example, a foreland basin system has been forming since ~80 Ma over an area previously affected by rift tectonics during the Mesozoic. This setting of Cenozoic contractile deformation superposed on continental crust pre-strained by extensional processes thus represents a natural, yet poorly studied experimental set-up, where the role of tectonic inheritance on the development of foreland basin systems can be evaluated. However, a detailed documentation of the early foreland basin evolution in this part of the Andes has thus far only been accomplished in the more internal sectors of the orogen. In this study, I integrate new structural, sedimentological and biostratigraphic data with low-temperature thermochronology from the eastern sector of the Colombian Andes, in order to provide the first comprehensive account of mountain building and related foreland basin sedimentation in this part of the orogen, and to assess as to what extent pre-existent basement anisotropies have conditioned the locus of foreland deformation in space and time. In the Medina Basin, along the eastern flank of the Eastern Cordillera, I integrated detailed structural mapping and new sedimentological data with a new chronostratigraphic framework based on detailed palynology that links an eastward-thinning early Oligocene to early Miocene syntectonic wedge containing rapid facies changes with an episode of fast tectonic subsidence starting at ~30 Ma. This record represents the first evidence of topographic loading generated by slip along the principal basement-bounding thrusts in the Eastern Cordillera to the west of the basin and thus constrains the onset of mountain building in this area. A comprehensive assessment of exhumation patterns based on zircon fission-track (ZFT), apatite fission-track (AFT) analysis and thermal modelling reveals the location of these thrust loads to have been located along the contractionally reactivated Soapaga Fault in the axial sector of the Eastern Cordillera. Farther to the east, AFT and ZFT data also document the onset of thrust-induced exhumation associated with contractional reactivation of the main range-bounding Servita Fault at ~20 Ma. Associated with this episode of orogenic growth, peak burial temperature estimates based on vitrinite reflectance data in the Cenozoic sedimentary record of the adjacent Medina Basin documents earlier incorporation of the western sector of the basin into the advancing fold and thrust belt. I combined these new thermochronological data with published AFT analyses and known chronologic indicators of brittle deformation in order to evaluate the patterns of orogenic-front migration in the Andes of central Colombia. This spatiotemporal analysis of deformation reveals an episodic pattern of eastward migration of the orogenic front at an average rate of 2.5-2.7 mm/yr during the Late Cretaceous-Cenozoic. I identified three major stages of orogen propagation. First, following initiation of mountain building in the Central Cordillera during the Late Cretaceous, the orogenic front propagate eastward at slow rates (0.5-3.1 mm/yr) until early Eocene times. Such slow orogenic advance would have resulted from limited accretionary flux related to slow and oblique (SW-NE-oriented) convergence of the Farallon and South American plates during that time. A second stage of rapid orogenic advance (4.0-18.0 mm/yr) during the middle-late Eocene, and locally of at least 100 mm/yr in the middle Eocene, resulted from initial tectonic inversion of the Eastern Cordillera. I correlate this episode of rapid orogen-front migration with an increase in the accretionary flux triggered by acceleration in convergence and a rotation of the convergence vector to a more orogen-perpendicular direction. Finally, stagnation of the Miocene deformation front along former rift-bounding reactivated faults in the eastern flank of the Eastern Cordillera led to a decrease in the rates of orogenic advance. Post-late Miocene-Pliocene thrusting along the actively deforming front of the Eastern Cordillera at this latitude suggests averaged Miocene-Holocene orogen propagation rates of 1.2-2.1 mm/yr. In addition, ZFT data suggest that exhumation along the eastern flank of the orogen occurred at moderate rates of ~0.3 mm/yr during the Miocene, prior to an acceleration of exhumation since the Pliocene, as suggested by recently published AFT data. In order to evaluate the relations between thrust loading and sedimentary facies evolution in the foreland, I analyzed gravel progradation in the foreland basin system. In particular, I compared one-dimensional Eocene to Pliocene sediment accumulation rates in the Medina basin with a three-dimensional sedimentary budget based on the interpretation of ~1800 km of industry-style seismic reflection profiles and borehole data tied to the new chronostratigraphic framework. The sedimentological data from the Medina Basin reveal rapid accumulation of fluvial and lacustrine sediments at rates of up to ~ 0.5 mm/yr during the Miocene. Provenance data based on gravel petrography and paleocurrents reveal that these Miocene fluvial systems were sourced by Upper Cretaceous and Paleocene sedimentary units exposed to the west, in the Eastern Cordillera. Peak sediment-accumulation rates in the upper Carbonera Formation and the Guayabo Group occur during episodes of gravel progradation in the proximal foredeep in the Early and Late Miocene. I interpreted this positive correlation between sediment accumulation and gravel deposition as the direct consequence of thrust activity in the Servita-Lengup{\´a} Fault. This contrasts with current models relating gravel progradation to episodes of tectonic quiescence in more distal portions of foreland basin systems and calls for a re-evaluation of tectonic history interpretations inferred from sedimentary units in other mountain belts. In summary, my results document a late Eocene-early Miocene eastward advance of the topographic loads associated with the leading edge of deformation in the northern Andes of Colombia. Crustal thickening of the Eastern Cordillera associated with initiation of thrusting along the Servit{\´a} Fault illustrates that this sector of the Andean orogen acquired ~90\% of its present width already by the early Miocene (~20 Ma). My data thus demonstrate that inherited crustal anisotropies, such as the former rift-bounding faults of the Eastern Cordillera, favour a non-systematic progression of foreland basin deformation through time by preferentially concentrating accommodation of slip and thrust-loading. These new chronology of exhumation and deformation associated with specific structures in the Colombian Andes also constitutes an important advance towards the understanding of models for hydrocarbon maturation, migration and trap formation along the prolific petroleum province of the Llanos Basin in the modern foredeep area.}, language = {en} } @phdthesis{Thieken2009, author = {Thieken, Annegret}, title = {Floods, flood losses and flood risk management in Germany}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-29164}, school = {Universit{\"a}t Potsdam}, year = {2009}, abstract = {Die vorliegende Habilitation besch{\"a}ftigt sich mit verschiedenen Aspekten des Hochwasserrisikos in Deutschland. In zw{\"o}lf Artikeln werden neue wissenschaftliche Erkenntnisse {\"u}ber Hochwassergefahren, {\"u}ber Faktoren, die Hochwassersch{\"a}den beeinflussen, sowie {\"u}ber effektive private Vorsorgemaßnahmen pr{\"a}sentiert. So wird die jahreszeitliche Verteilung von Hochwasser in ganz Deutschland gezeigt. Weiterhin werden m{\"o}gliche Auswirkungen des Klimawandels auf Abflussverh{\"a}ltnisse und H{\"a}ufigkeiten von Hochwasserereignissen am Beispiel des Rhein-Einzugsgebietes abgesch{\"a}tzt. Ferner wird am Niederrhein simuliert, welche Auswirkungen Deichbr{\"u}che haben k{\"o}nnen. Hochwassersch{\"a}den stehen im zweiten Teil der Arbeit im Fokus: Nach dem August-Hochwasser 2002 wurden ca. 1700 Privathaushalte telefonisch befragt. Damit konnten die Einfl{\"u}sse verschiedener Faktoren, wie der {\"U}berflutungsdauer oder der Verunreinigung des Hochwassers mit {\"O}l, auf die H{\"o}he von finanziellen Sch{\"a}den quantifiziert werden. Daraus ist zum einen ein neues Modell entstanden, mit dem Hochwassersch{\"a}den großr{\"a}umig berechnet werden k{\"o}nnen. Zum anderen konnten Hinweise f{\"u}r die Verbesserung der privaten Vorsorge abgeleitet werden. Beispielsweise zeigte sich, dass versicherte Haushalte schneller und besser entsch{\"a}digt werden als Nicht-Versicherte. Ebenfalls wurde deutlich, dass verschiedene Bev{\"o}lkerungsgruppen, wie Mieter und Hauseigent{\"u}mer, unterschiedliche M{\"o}glichkeiten haben, Vorsorge zu betreiben. Dies ist zuk{\"u}nftig in der Risikokommunikation zu ber{\"u}cksichtigen. In den Jahren 2005 und 2006 waren Elbe und Donau wiederum von Hochwasser betroffen. Eine erneute Befragung von Privathaushalten und Beh{\"o}rden erm{\"o}glichte, die Verbesserung des Hochwasserrisikomanagement und der Vorsorge am Beispiel der Stadt Dresden zu untersuchen. Viele Methoden und Erkenntnisse dieser Arbeit sind in der wasserwirtschaftlichen Praxis anwendbar und tragen somit zur Verbesserung der Hochwasserrisikoanalyse und des Risikomanagements in Deutschland bei.}, language = {en} } @phdthesis{Boerner2009, author = {B{\"o}rner, Hans Gerhard}, title = {Exploiting self-organization and functionality of peptides for polymer science}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-29066}, school = {Universit{\"a}t Potsdam}, year = {2009}, abstract = {Controlling interactions in synthetic polymers as precisely as in proteins would have a strong impact on polymer science. Advanced structural and functional control can lead to rational design of, integrated nano- and microstructures. To achieve this, properties of monomer sequence defined oligopeptides were exploited. Through their incorporation as monodisperse segments into synthetic polymers we learned in recent four years how to program the structure formation of polymers, to adjust and exploit interactions in such polymers, to control inorganic-organic interfaces in fiber composites and induce structure in Biomacromolecules like DNA for biomedical applications.}, language = {en} } @phdthesis{Schmitz2008, author = {Schmitz, Michaela}, title = {The perception of clauses in 6- and 8-month-old German-learning infants : influence of pause duration and the natural pause hierarchy}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-29078}, school = {Universit{\"a}t Potsdam}, year = {2008}, abstract = {The present dissertation focuses on the question whether and under which conditions infants recognise clauses in fluent speech and the role a prosodic marker such as a pause may have in the segmentation process. In the speech signal, syntactic clauses often coincide with intonational phrases (IPhs) (Nespor \& Vogel, 1986, p. 190), the boundaries of which are marked by changes in fundamental frequency (e.g., Price, Ostendorf, Shattuck-Hufnagel \& Fong, 1991), lengthening of the final syllable (e.g., Cooper \& Paccia-Cooper, 1980) and the occurrence of a pause (Nespor \& Vogel, 1986, p. 188). Thus, IPhs seem to be reliably marked in the speech stream and infants may use these cues to recognise them. Furthermore, corpus studies on the occurrence and distribution of pauses have revealed that there is a strong correlation between the duration of a pause and the type of boundary it marks (e.g., Butcher, 1981, for German). Pauses between words are either non-existent or short, pauses between phrases are a bit longer, and pauses between clauses and at sentence boundaries further increase in duration. This suggests the existence of a natural pause hierarchy that complements the prosodic hierarchy described by Nespor and Vogel (1986). These hierarchies on the side of the speech signal correspond to the syntactic hierarchy of a language. In the present study, five experiments using the Headturn preference paradigm (Hirsh-Pasek, Kemler Nelson, Jusczyk, Cassidy, Druss \& Kennedy, 1987) were conducted to investigate German-learning 6- and 8-month-olds' use of pauses to recognise clauses in the signal and their sensitivity to the natural pause hierarchy. Previous studies on English-learning infants' recognition of clauses (Hirsh-Pasek et al., 1987; Nazzi, Kemler Nelson, Jusczyk \& Jusczyk, 2000) have found that infants as young as 6 months recognise clauses in fluent speech. Recently, Seidl and colleagues have begun to investigate the status the pause may have in this process (Seidl, 2007; Johnson \& Seidl, 2008; Seidl \& Cristi{\`a}, 2008). However, none of these studies investigated infants' sensitivity to the natural pause hierarchy and especially the sensitivity to the correlation between pause durations and the respective within-sentence clause boundaries / sentence boundaries. To address these questions highly controlled stimuli were used. In all five experiments the stimuli were sentences consisting of two IPhs which each coincided with a syntactic clause. In the first three experiments pauses were inserted either at clause and sentence boundaries or within the first clause and the sentence boundaries. The duration of the pauses varied between the experiments. The results show that German-learning 6-month-olds recognise clauses in the speech stream, but only in a condition in which the duration of the pauses conforms to the mean duration of pauses found at the respective boundaries in German. Experiments 4 and 5 explicitly addressed the question of infants' sensitivity to the natural pause hierarchy by inserting pauses at the clause and sentence boundaries only. Their durations were either conforming to the natural pause hierarchy or were being reversed. The results of these experiments provide evidence that 8-, but not 6-month-olds seem to be sensitive to the correlation of the duration of pauses and the type of boundary they demarcate. The present study provides first evidence that infants not only use pauses to recognise clause and sentence boundaries, but are sensitive to the duration and distribution of pauses in their native language as reflected in the natural pause hierarchy.}, language = {en} } @phdthesis{Li2008, author = {Li, Yanhong}, title = {Phase separation in giant vesicles}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-29138}, school = {Universit{\"a}t Potsdam}, year = {2008}, abstract = {Giant vesicles may contain several spatial compartments formed by phase separation within their enclosed aqueous solution. This phenomenon might be related to molecular crowding, fractionation and protein sorting in cells. To elucidate this process we used two chemically dissimilar polymers, polyethylene glycol (PEG) and dextran, encapsulated in giant vesicles. The dynamics of the phase separation of this polymer solution enclosed in vesicles is studied by concentration quench, i.e. exposing the vesicles to hypertonic solutions. The excess membrane area, produced by dehydration, can either form tubular structures (also known as tethers) or be utilized to perform morphological changes of the vesicle, depending on the interfacial tension between the coexisting phases and those between the membrane and the two phases. Membrane tube formation is coupled to the phase separation process. Apparently, the energy released from the phase separation is utilized to overcome the energy barrier for tube formation. The tubes may be absorbed at the interface to form a 2-demensional structure. The membrane stored in the form of tubes can be retracted under small tension perturbation. Furthermore, a wetting transition, which has been reported only in a few experimental systems, was discovered in this system. By increasing the polymer concentration, the PEG-rich phase changed from complete wetting to partial wetting of the membrane. If sufficient excess membrane area is available in the vesicle where both phases wet the membrane, one of the phases will bud off from the vesicle body, which leads to the separation of the two phases. This wetting-induced budding is governed by the surface energy and modulated by the membrane tension. This was demonstrated by micropipette aspiration experiments on vesicles encapsulating two phases. The budding of one phase can significantly decrease the surface energy by decreasing the contact area between the coexisting phases. The elasticity of the membrane allows it to adjust its tension automatically to balance the pulling force exerted by the interfacial tension of the two liquid phases at the three-phase contact line. The budding of the phase enriched with one polymer may be relevant to the selective protein transportation among lumens by means of vesicle in cells.}, language = {en} } @phdthesis{Gressel2008, author = {Gressel, Oliver}, title = {Supernova-driven turbulence and magnetic field amplification in disk galaxies}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-29094}, school = {Universit{\"a}t Potsdam}, year = {2008}, abstract = {Supernovae are known to be the dominant energy source for driving turbulence in the interstellar medium. Yet, their effect on magnetic field amplification in spiral galaxies is still poorly understood. Analytical models based on the uncorrelated-ensemble approach predicted that any created field will be expelled from the disk before a significant amplification can occur. By means of direct simulations of supernova-driven turbulence, we demonstrate that this is not the case. Accounting for vertical stratification and galactic differential rotation, we find an exponential amplification of the mean field on timescales of 100Myr. The self-consistent numerical verification of such a "fast dynamo" is highly beneficial in explaining the observed strong magnetic fields in young galaxies. We, furthermore, highlight the importance of rotation in the generation of helicity by showing that a similar mechanism based on Cartesian shear does not lead to a sustained amplification of the mean magnetic field. This finding impressively confirms the classical picture of a dynamo based on cyclonic turbulence.}, language = {en} } @phdthesis{Yin2009, author = {Yin, Chunhong}, title = {The interplay of nanostructure and efficiency of polymer solar cells}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-29054}, school = {Universit{\"a}t Potsdam}, year = {2009}, abstract = {The aim of this thesis is to achieve a deep understanding of the working mechanism of polymer based solar cells and to improve the device performance. Two types of the polymer based solar cells are studied here: all-polymer solar cells comprising macromolecular donors and acceptors based on poly(p-phenylene vinylene) and hybrid cells comprising a PPV copolymer in combination with a novel small molecule electron acceptor. To understand the interplay between morphology and photovoltaic properties in all-polymer devices, I compared the photocurrent characteristics and excited state properties of bilayer and blend devices with different nano-morphology, which was fine tuned by using solvents with different boiling points. The main conclusion from these complementary measurements was that the performance-limiting step is the field-dependent generation of free charge carriers, while bimolecular recombination and charge extraction do not compromise device performance. These findings imply that the proper design of the donor-acceptor heterojunction is of major importance towards the goal of high photovoltaic efficiencies. Regarding polymer-small molecular hybrid solar cells I combined the hole-transporting polymer M3EH-PPV with a novel Vinazene-based electron acceptor. This molecule can be either deposited from solution or by thermal evaporation, allowing for a large variety of layer architectures to be realized. I then demonstrated that the layer architecture has a large influence on the photovoltaic properties. Solar cells with very high fill factors of up to 57 \% and an open circuit voltage of 1V could be achieved by realizing a sharp and well-defined donor-acceptor heterojunction. In the past, fill factors exceeding 50 \% have only been observed for polymers in combination with soluble fullerene-derivatives or nanocrystalline inorganic semiconductors as the electron-accepting component. The finding that proper processing of polymer-vinazene devices leads to similar high values is a major step towards the design of efficient polymer-based solar cells.}, language = {en} } @book{Nosova2008, author = {Nosova, Olga}, title = {Statistical analysis of regional integration effects}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-29106}, publisher = {Universit{\"a}t Potsdam}, year = {2008}, abstract = {The paper studies the regional integration as the unique process which depends on the degree of cooperation and interchange among regions. The generalisation of existing approaches for regional integration has been classified by the criterions. The data of the main economic indicators have been analysed. The economic analysis proves the differences in production endowments, the asymmetry in fixed capital investment, the disproportional income, and foreign direct investment distribution in 2001 - 2005 in Ukrainian regions. Econometric modelling depicts the existence of the division for the industrial regions with high urbanisation and backward agrarian regions in the Ukraine, the industrial development disparities among regions; the insufficient infrastructure (telecommunications, roads, hotels, services and etc.), the low labour productivity in industrial sector, and insufficient regional trade.}, language = {en} } @phdthesis{Zhang2008, author = {Zhang, Bo}, title = {Magnetic fields near microstructured surfaces : application to atom chips}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-28984}, school = {Universit{\"a}t Potsdam}, year = {2008}, abstract = {Microfabricated solid-state surfaces, also called atom chip', have become a well-established technique to trap and manipulate atoms. This has simplified applications in atom interferometry, quantum information processing, and studies of many-body systems. Magnetic trapping potentials with arbitrary geommetries are generated with atom chip by miniaturized current-carrying conductors integrated on a solid substrate. Atoms can be trapped and cooled to microKelvin and even nanoKelvin temperatures in such microchip trap. However, cold atoms can be significantly perturbed by the chip surface, typically held at room temperature. The magnetic field fluctuations generated by thermal currents in the chip elements may induce spin flips of atoms and result in loss, heating and decoherence. In this thesis, we extend previous work on spin flip rates induced by magnetic noise and consider the more complex geometries that are typically encountered in atom chips: layered structures and metallic wires of finite cross-section. We also discuss a few aspects of atom chips traps built with superconducting structures that have been suggested as a means to suppress magnetic field fluctuations. The thesis describes calculations of spin flip rates based on magnetic Green functions that are computed analytically and numerically. For a chip with a top metallic layer, the magnetic noise depends essentially on the thickness of that layer, as long as the layers below have a much smaller conductivity. Based on this result, scaling laws for loss rates above a thin metallic layer are derived. A good agreement with experiments is obtained in the regime where the atom-surface distance is comparable to the skin depth of metal. Since in the experiments, metallic layers are always etched to separate wires carrying different currents, the impact of the finite lateral wire size on the magnetic noise has been taken into account. The local spectrum of the magnetic field near a metallic microstructure has been investigated numerically with the help of boundary integral equations. The magnetic noise significantly depends on polarizations above flat wires with finite lateral width, in stark contrast to an infinitely wide wire. Correlations between multiple wires are also taken into account. In the last part, superconducting atom chips are considered. Magnetic traps generated by superconducting wires in the Meissner state and the mixed state are studied analytically by a conformal mapping method and also numerically. The properties of the traps created by superconducting wires are investigated and compared to normal conducting wires: they behave qualitatively quite similar and open a route to further trap miniaturization, due to the advantage of low magnetic noise. We discuss critical currents and fields for several geometries.}, language = {en} } @phdthesis{Oey2008, author = {Oey, Melanie}, title = {Chloroplasts as bioreactors : high-yield production of active bacteriolytic protein antibiotics}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-28950}, school = {Universit{\"a}t Potsdam}, year = {2008}, abstract = {Plants, more precisely their chloroplasts with their bacterial-like expression machinery inherited from their cyanobacterial ancestors, can potentially offer a cheap expression system for proteinaceous pharmaceuticals. This system would be easily scalable and provides appropriate safety due to chloroplasts maternal inheritance. In this work, it was shown that three phage lytic enzymes (Pal, Cpl-1 and PlyGBS) could be successfully expressed at very high levels and with high stability in tobacco chloroplasts. PlyGBS expression reached an amount of foreign protein accumulation (> 70\% TSP) that has never been obtained before. Although the high expression levels of PlyGBS caused a pale green phenotype with retarded growth, presumably due to exhaustion of plastid protein synthesis capacity, development and seed production were not impaired under greenhouse conditions. Since Pal and Cpl-1 showed toxic effects when expressed in E. coli, a special plastid transformation vector (pTox) was constructed to allow DNA amplification in bacteria. The construction of the pTox transformation vector allowing a recombinase-mediated deletion of an E. coli transcription block in the chloroplast, leading to an increase of foreign protein accumulation to up to 40\% of TSP for Pal and 20\% of TSP for Cpl-1. High dose-dependent bactericidal efficiency was shown for all three plant-derived lytic enzymes using their pathogenic target bacteria S. pyogenes and S. pneumoniae. Confirmation of specificity was obtained for the endotoxic proteins Pal and Cpl-1 by application to E. coli cultures. These results establish tobacco chloroplasts as a new cost-efficient and convenient production platform for phage lytic enzymes and address the greatest obstacle for clinical application. The present study is the first report of lysin production in a non-bacterial system. The properties of chloroplast-produced lysins described in this work, their stability, high accumulation rate and biological activity make them highly attractive candidates for future antibiotics.}, language = {en} } @inproceedings{Guenzel2008, author = {G{\"u}nzel, Stephan}, title = {The space-image}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-24561}, year = {2008}, abstract = {In recent computer game research a paradigmatic shift is observable: Games today are first and foremost conceived as a new medium characterized by their status as an interactive image. The shift in attention towards this aspect becomes apparent in a new approach that is, first and foremost, aware of the spatiality of games or their spatial structures. This rejects traditional approaches on the basis that the medial specificity of games can no longer be reduced to textual or ludic properties, but has to be seen in medial constituted spatiality. For this purpose, seminal studies on the spatiality of computer games are resumed and their advantages and disadvantages are discussed. In connection with this, and against the background of the philosophical method of phenomenology, we propose three steps in describing computer games as space images: With this method it is possible to describe games with respect to the possible appearance of spatiality in a pictorial medium.}, language = {en} } @inproceedings{MuellerCoppockLiebeetal.2008, author = {M{\"u}ller, Petra and Coppock, Patrick and Liebe, Michael and Mersch, Dieter and Bogost, Ian and Bartle, Richard and Juul, Jesper and L{\o}vlie, Anders Sundnes and Pohl, Kirsten and Schrape, Niklas and Hoffstadt, Christian and Nagenborg, Michael and Liboriussen, Bjarke and Meldgaard, Betty Li and G{\"u}nzel, Stephan and Ljungstr{\"o}m, Mattias and Jennett, Charlene and Cox, Anna L. and Cairns, Paul and Mukherjee, Souvik and Pinchbeck, Dan and Glash{\"u}ttner, Robert}, title = {Conference proceedings of The Philosophy of Computer Games 2008}, editor = {G{\"u}nzel, Stephan and Liebe, Michael and Mersch, Dieter}, publisher = {Universit{\"a}tsverlag Potsdam}, address = {Potsdam}, isbn = {978-3-940793-49-2}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-20072}, pages = {341}, year = {2008}, abstract = {This first volume of the DIGAREC Series holds the proceedings of the conference "The Philosophy of Computer Games", held at the University of Potsdam from May 8-10, 2008. The contributions of the conference address three fields of computer game research that are philosophically relevant and, likewise, to which philosophical reflection is crucial. These are: ethics and politics, the action-space of games, and the magic circle. All three topics are interlinked and constitute the paradigmatic object of computer games: Whereas the first describes computer games on the outside, looking at the cultural effects of games as well as on moral practices acted out with them, the second describes computer games on the inside, i.e. how they are constituted as a medium. The latter finally discusses the way in which a border between these two realms, games and non-games, persists or is already transgressed in respect to a general performativity.}, language = {en} } @phdthesis{Foerster2008, author = {F{\"o}rster, Saskia}, title = {An analysis of hydraulic, environmental and economic impacts of flood polder management at the Elbe River}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-27260}, school = {Universit{\"a}t Potsdam}, year = {2008}, abstract = {Flood polders are part of the flood risk management strategy for many lowland rivers. They are used for the controlled storage of flood water so as to lower peak discharges of large floods. Consequently, the flood hazard in adjacent and downstream river reaches is decreased in the case of flood polder utilisation. Flood polders are usually dry storage reservoirs that are typically characterised by agricultural activities or other land use of low economic and ecological vulnerability. The objective of this thesis is to analyse hydraulic, environmental and economic impacts of the utilisation of flood polders in order to draw conclusions for their management. For this purpose, hydrodynamic and water quality modelling as well as an economic vulnerability assessment are employed in two study areas on the Middle Elbe River in Germany. One study area is an existing flood polder system on the tributary Havel, which was put into operation during the Elbe flood in summer 2002. The second study area is a planned flood polder, which is currently in the early planning stages. Furthermore, numerical models of different spatial dimensionality, ranging from zero- to two-dimensional, are applied in order to evaluate their suitability for hydrodynamic and water quality simulations of flood polders in regard to performance and modelling effort. The thesis concludes with overall recommendations on the management of flood polders, including operational schemes and land use. In view of future changes in flood frequency and further increasing values of private and public assets in flood-prone areas, flood polders may be effective and flexible technical flood protection measures that contribute to a successful flood risk management for large lowland rivers.}, language = {en} } @phdthesis{RianoPachon2008, author = {Ria{\~n}o-Pach{\´o}n, Diego Mauricio}, title = {Identification of transcription factor genes in plants}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-27009}, school = {Universit{\"a}t Potsdam}, year = {2008}, abstract = {In order to function properly, organisms have a complex control mechanism, in which a given gene is expressed at a particular time and place. One way to achieve this control is to regulate the initiation of transcription. This step requires the assembly of several components, i.e., a basal/general machinery common to all expressed genes, and a specific/regulatory machinery, which differs among genes and is the responsible for proper gene expression in response to environmental or developmental signals. This specific machinery is composed of transcription factors (TFs), which can be grouped into evolutionarily related gene families that possess characteristic protein domains. In this work we have exploited the presence of protein domains to create rules that serve for the identification and classification of TFs. We have modelled such rules as a bipartite graph, where families and protein domains are represented as nodes. Connections between nodes represent that a protein domain should (required rule) or should not (forbidden rule) be present in a protein to be assigned into a TF family. Following this approach we have identified putative complete sets of TFs in plant species, whose genome is completely sequenced: Cyanidioschyzon merolae (red algae), Chlamydomonas reinhardtii (green alga), Ostreococcus tauri (green alga), Physcomitrella patens (moss), Arabidopsis thaliana (thale cress), Populus trichocarpa (black cottonwood) and Oryza sativa (rice). The identification of the complete sets of TFs in the above-mentioned species, as well as additional information and reference literature are available at http://plntfdb.bio.uni-potsdam.de/. The availability of such sets allowed us performing detailed evolutionary studies at different levels, from a single family to all TF families in different organisms in a comparative genomics context. Notably, we uncovered preferential expansions in different lineages, paving the way to discover the specific biological roles of these proteins under different conditions. For the basic leucine zipper (bZIP) family of TFs we were able to infer that in the most recent common ancestor (MRCA) of all green plants there were at least four bZIP genes functionally involved in oxidative stress and unfolded protein responses that are bZIP-mediated processes in all eukaryotes, but also in light-dependent regulations. The four founder genes amplified and diverged significantly, generating traits that benefited the colonization of new environments. Currently, following the approach described above, up to 57 TF and 11 TR families can be identified, which are among the most numerous transcription regulatory families in plants. Three families of putative TFs predate the split between rhodophyta (red algae) and chlorophyta (green algae), i.e., G2-like, PLATZ, and RWPRK, and may have been of particular importance for the evolution of eukaryotic photosynthetic organisms. Nine additional families, i.e., ABI3/VP1, AP2-EREBP, ARR-B, C2C2-CO-like, C2C2-Dof, PBF-2-like/Whirly, Pseudo ARR-B, SBP, and WRKY, predate the split between green algae and streptophytes. The identification of putative complete list of TFs has also allowed the delineation of lineage-specific regulatory families. The families SBP, bHLH, SNF2, MADS, WRKY, HMG, AP2-EREBP and FHA significantly differ in size between algae and land plants. The SBP family of TFs is significantly larger in C. reinhardtii, compared to land plants, and appears to have been lost in the prasinophyte O. tauri. The families bHLH, SNF2, MADS, WRKY, HMG, AP2-EREBP and FHA preferentially expanded with the colonisation of land, and might have played an important role in this great moment in evolution. Later, after the split of bryophytes and tracheophytes, the families MADS, AP2-EREBP, NAC, AUX/IAA, PHD and HRT have significantly larger numbers in the lineage leading to seed plants. We identified 23 families that are restricted to land plants and that might have played an important role in the colonization of this new habitat. Based on the list of TFs in different species we have started to develop high-throughput experimental platforms (in rice and C. reinhardtii) to monitor gene expression changes of TF genes under different genetic, developmental or environmental conditions. In this work we present the monitoring of Arabidopsis thaliana TFs during the onset of senescence, a process that leads to cell and tissue disintegration in order to redistribute nutrients (e.g. nitrogen) from leaves to reproductive organs. We show that the expression of 185 TF genes changes when leaves develop from half to fully expanded leaves and finally enter partial senescence. 76\% of these TFs are down-regulated during senescence, the remaining are up-regulated. The identification of TFs in plants in a comparative genomics setup has proven fruitful for the understanding of evolutionary processes and contributes to the elucidation of complex developmental programs.}, language = {en} } @misc{Flassig2008, type = {Master Thesis}, author = {Flassig, Robert Johann}, title = {Dusty ringlets in Saturn's ring system}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-27046}, school = {Universit{\"a}t Potsdam}, year = {2008}, abstract = {Recently, several faint ringlets in the Saturnian ring system were found to maintain a peculiar orientation relative to Sun. The Encke gap ringlets as well as the ringlet in the outer rift of the Cassini division were found to have distinct spatial displacements of several tens of kilometers away from Saturn towards Sun, referred to as heliotropicity (Hedman et al., 2007). This is quite exceptional, since dynamically one would expect eccentric features in the Saturnian rings to precess around Saturn over periods of months. In our study we address this exceptional behavior by investigating the dynamics of circumplanetary dust particles with sizes in the range of 1-100 µm. These small particles are perturbed by non-gravitational forces, in particular, solar radiation pres- sure, Lorentz force, and planetary oblateness, on time-scales of the order of days. The combined influences of these forces cause periodical evolutions of grains' orbital ec- centricities as well as precession of their pericenters, which can be shown by secular perturbation theory. We show that this interaction results in a stationary eccentric ringlet, oriented with its apocenter towards the Sun, which is consistent with obser- vational findings. By applying this heliotropic dynamics to the central Encke gap ringlet, we can give a limit for the expected smallest grain size in the ringlet of about 8.7 microns, and constrain the minimal lifetime to lie in the order of months. Furthermore, our model matches fairly well the observed ringlet eccentricity in the Encke gap, which supports recent estimates on the size distribution of the ringlet material (Hedman et al., 2007). The ringlet-width however, that results from our modeling based on heliotropic dynamics, slightly overestimates the observed confined ringlet-width by a factor of 3 to 10, depending on the width-measure being used. This is indicative for mechanisms, not included in the heliotropic model, which potentially confine the ringlet to its observed width, including shepherding and scattering by embedded moonlets in the ringlet region. Based on these results, early investigations (Cuzzi et al., 1984, Spahn and Wiebicke, 1989, Spahn and Sponholz, 1989), and recent work that has been published on the F ring (Murray et al., 2008) - to which the Encke gap ringlets are found to share similar morphological structures - we model the maintenance of the central ringlet by embedded moonlets. These moonlets, believed to have sizes of hundreds of meters across, release material into space, which is eroded by micrometeoroid bombardment (Divine, 1993). We further argue that Pan - one of Saturn's moons, which shares its orbit with the central ringlet of the Encke gap - is a rather weak source of ringlet material that efficiently confines the ringlet sources (moonlets) to move on horseshoe-like orbits. Moreover, we suppose that most of the narrow heliotropic ringlets are fed by a moonlet population, which is held together by the largest member to move on horseshoe-like orbits. Modeling the equilibrium between particle source and sinks with a primitive balance equation based on photometric observations (Porco et al., 2005), we find the minimal effective source mass of the order of 3 · 10-2MPan, which is needed to keep the central ringlet from disappearing.}, language = {en} } @inproceedings{OPUS4-2516, title = {Finite-state methods and natural language processing : 6th International Workshop, FSMNLP 2007 Potsdam, Germany, september 14 - 16 ; revised papers}, editor = {Hanneforth, Thomas and W{\"u}rzner, Kay-Michael}, publisher = {Universit{\"a}tsverlag Potsdam}, address = {Potsdam}, isbn = {978-3-940793-57-7}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-23812}, pages = {225}, year = {2008}, abstract = {Proceedings with the revised papers of the FSMNLP (Finite-state Methods and Natural Language Processing) 2007 Workshop in Potsdam}, language = {en} } @phdthesis{Weikl2007, author = {Weikl, Thomas R.}, title = {Transition states and loop-closure principles in protein folding}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-26975}, school = {Universit{\"a}t Potsdam}, year = {2007}, abstract = {Proteins are chain molecules built from amino acids. The precise sequence of the 20 different types of amino acids in a protein chain defines into which structure a protein folds, and the three-dimensional structure in turn specifies the biological function of the protein. The reliable folding of proteins is a prerequisite for their robust function. Misfolding can lead to protein aggregates that cause severe diseases, such as Alzheimer's, Parkinson's, or the variant Creutzfeldt-Jakob disease. Small single-domain proteins often fold without experimentally detectable metastable intermediate states. The folding dynamics of these proteins is thought to be governed by a single transition-state barrier between the unfolded and the folded state. The transition state is highly instable and cannot be observed directly. However, mutations in which a single amino acid of the protein is substituted by another one can provide indirect access. The mutations slightly change the transition-state barrier and, thus, the folding and unfolding times of the protein. The central question is how to reconstruct the transition state from the observed changes in folding times. In this habilitation thesis, a novel method to extract structural information on transition states from mutational data is presented. The method is based on (i) the cooperativity of structural elements such as alpha-helices and beta-hairpins, and (ii) on splitting up mutation-induced free-energy changes into components for these elements. By fitting few parameters, the method reveals the degree of structure formation of alpha-helices and beta-hairpins in the transition state. In addition, it is shown in this thesis that the folding routes of small single-domain proteins are dominated by loop-closure dependencies between the structural elements.}, language = {en} } @techreport{PetersenKirchner2008, type = {Working Paper}, author = {Petersen, Hans-Georg and Kirchner, Markus}, title = {Education return and financing}, issn = {1864-1431}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-26969}, year = {2008}, abstract = {The paper sheds some light on the education returns in Germany in the post war period. After describing higher education in Germany the current stand of higher education financing within the single states is presented. In six states tuition fees will be introduced in 2007/08 and discussions are going on in even some more. In the second part of the paper an empirical analysis is done using longitudinal data from the German social pension system. The analysis over the whole lifecycle renders results which proof that the higher education advantages are quite remarkable and might be a justification for more intensified financing by tuition fees. But all this has to be embedded into an encompassing strategy of tax and social policy, especially to prevent a strengthened process of social selection, which would be counterproductive for an increased and highly qualified human capital in Germany.}, language = {en} } @phdthesis{Tirok2008, author = {Tirok, Katrin}, title = {Predator-prey dynamics under the influence of exogenous and endogenous regulation : a data-based modeling study on spring plankton with respect to climate change}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-24528}, school = {Universit{\"a}t Potsdam}, year = {2008}, abstract = {Understanding the interactions of predators and their prey and their responses to environmental changes is one of the striking features of ecological research. In this thesis, spring dynamics of phytoplankton and its consumers, zooplankton, were considered in dependence on the environmental conditions in a deep lake (Lake Constance) and a shallow marine water (mesocosms from Kiel Bight), using descriptive statistics, multiple regression models, and process-oriented dynamic simulation models. The development of the spring phytoplankton bloom, representing a dominant feature in the plankton dynamics in temperate and cold oceans and lakes, may depend on temperature, light, and mixing intensity, and the success of over-wintering phyto- and zooplankton. These factors are often correlated in the field. Unexpectedly, irradiance often dominated algal net growth rather than vertical mixing even in deep Lake Constance. Algal net losses from the euphotic layer to larger depth were induced by vertical mixing, but were compensated by the input from larger depth when algae were uniformly distributed over the water column. Dynamics of small, fast-growing algae were well predicted by abiotic variables, such as surface irradiance, vertical mixing intensity, and temperature. A simulation model additionally revealed that even in late winter, grazing may represent an important loss factor of phytoplankton during calm periods when losses due to mixing are small. The importance of losses by mixing and grazing changed rapidly as it depended on the variable mixing intensity. Higher temperature, lower global irradiance and enhanced mixing generated lower algal biomass and primary production in the dynamic simulation model. This suggests that potential consequences of climate change may partly counteract each other. The negative effect of higher temperatures on phytoplankton biomass was due to enhanced temperature-sensitive grazing losses. Comparing the results from deep Lake Constance to those of the shallow mesocosm experiments and simulations, confirmed the strong direct effect of light in contrast to temperature, and the importance of grazing already in early spring as soon as moderate algal biomasses developed. In Lake Constance, ciliates dominated the herbivorous zooplankton in spring. The start of ciliate net growth in spring was closely linked to that of edible algae, chlorophyll a and the vertical mixing intensity but independent of water temperature. The duration of ciliate dominance in spring was largely controlled by the highly variable onset of the phytoplankton bloom, and little by the less variable termination of the ciliate bloom by grazing of meta-zooplankton. During years with an extended spring bloom of algae and ciliates, they coexisted at relatively high biomasses over 15-30 generations, and internally forced species shifts were observed in both communities. Interception feeders alternated with filter feeders, and cryptomonads with non-cryptomonads in their relative importance. These dynamics were not captured by classical 1-predator-1-prey models which consistently predict pronounced predator-prey cycles or equilibria with either the predator or the prey dominating or suppressed. A multi-species predator-prey model with predator species differing in their food selectivity, and prey species in their edibility reproduced the observed patterns. Food-selectivity and edibility were related to the feeding and growth characteristics of the species, which represented ecological trade-offs. For example, the prey species with the highest edibility also had the highest maximum growth rate. Data and model revealed endogenous driven ongoing species alternations, which yielded a higher variability in species-specific biomasses than in total predator and prey biomass. This holds for a broad parameter space as long as the species differ functionally. A more sophisticated model approach enabled the simulation of a continuum of different functional types and adaptability of predator and prey communities to altered environmental conditions, and the maintenance of a rather low model complexity, i.e., low number of equations and free parameters. The community compositions were described by mean functional traits --- prey edibility and predator food-selectivity --- and their variances. The latter represent the functional diversity of the communities and thus, the potential for adaptation. Oscillations in the mean community trait values indicated species shifts. The community traits were related to growth and grazing characteristics representing similar trade-offs as in the multi-species model. The model reproduced the observed patterns, when nonlinear relationships between edibility and capacity, and edibility and food availability for the predator were chosen. A constant minimum amount of variance represented ongoing species invasions and thus, preserved a diversity which allows adaptation on a realistic time-span.}, language = {en} } @phdthesis{Lisec2008, author = {Lisec, Jan}, title = {Identification and characterization of metabolic Quantitative Trait Loci (QTL) in Arabidopsis thaliana}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-25903}, school = {Universit{\"a}t Potsdam}, year = {2008}, abstract = {Plants are the primary producers of biomass and thereby the basis of all life. Many varieties are cultivated, mainly to produce food, but to an increasing amount as a source of renewable energy. Because of the limited acreage available, further improvements of cultivated species both with respect to yield and composition are inevitable. One approach to further progress in developing improved plant cultivars is a systems biology oriented approach. This work aimed to investigate the primary metabolism of the model plant A.thaliana and its relation to plant growth using quantitative genetics methods. A special focus was set on the characterization of heterosis, the deviation of hybrids from their parental means for certain traits, on a metabolic level. More than 2000 samples of recombinant inbred lines (RILs) and introgression lines (ILs) developed from the two accessions Col-0 and C24 were analyzed for 181 metabolic traces using gas-chromatography/ mass-spectrometry (GC-MS). The observed variance allowed the detection of 157 metabolic quantitative trait loci (mQTL), genetic regions carrying genes, which are relevant for metabolite abundance. By analyzing several hundred test crosses of RILs and ILs it was further possible to identify 385 heterotic metabolic QTL (hmQTL). Within the scope of this work a robust method for large scale GC-MS analyses was developed. A highly significant canonical correlation between biomass and metabolic profiles (r = 0.73) was found. A comparable analysis of the results of the two independent experiments using RILs and ILs showed a large agreement. The confirmation rate for RIL QTL in ILs was 56 \% and 23 \% for mQTL and hmQTL respectively. Candidate genes from available databases could be identified for 67 \% of the mQTL. To validate some of these candidates, eight genes were re-sequenced and in total 23 polymorphisms could be found. In the hybrids, heterosis is small for most metabolites (< 20\%). Heterotic QTL gave rise to less candidate genes and a lower overlap between both populations than was determined for mQTL. This hints that regulatory loci and epistatic effects contribute to metabolite heterosis. The data described in this thesis present a rich source for further investigation and annotation of relevant genes and may pave the way towards a better understanding of plant biology on a system level.}, language = {en} } @phdthesis{Beyvers2008, author = {Beyvers, Stephanie}, title = {Selective excitation of adsorbate vibrations on dissipative surfaces}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-25516}, school = {Universit{\"a}t Potsdam}, year = {2008}, abstract = {The selective infrared (IR) excitation of molecular vibrations is a powerful tool to control the photoreactivity prior to electronic excitation in the ultraviolet / visible (UV/Vis) light regime ("vibrationally mediated chemistry"). For adsorbates on surfaces it has been theoretically predicted that IR preexcitation will lead to higher UV/Vis photodesorption yields and larger cross sections for other photoreactions. In a recent experiment, IR-mediated desorption of molecular hydrogen from a Si(111) surface on which atomic hydrogen and deuterium were co-adsorbed was achieved, following a vibrational mechanism as indicated by the isotope-selectivity. In the present work, selective vibrational IR excitation of adsorbate molecules, treated as multi-dimensional oscillators on dissipative surfaces, has been simulated within the framework of open-system density matrix theory. Not only potential-mediated, inter-mode coupling poses an obstacle to selective excitation but also the coupling of the adsorbate ("system") modes to the electronic and phononic degrees of freedom of the surface ("bath") does. Vibrational relaxation thereby takes place, depending on the availabilty of energetically fitting electron-hole (e/h) pairs and/or phonons (lattice vibrations) in the surface, on time-scales ranging from milliseconds to several hundreds of femtoseconds. On metal surfaces, where the relaxation process of the adsorbate via the e/h pair mechanism dominates, vibrational lifetimes are usually shorter than on insulator or semiconductor surfaces, in the range of picoseconds, being also the timescale of the IR pulses used here. Further inhibiting factors for selectivity can be the harmonicity of a mode and weak dipole activities ("dark modes") rendering vibrational excitation with moderate field intensities difficult. In addition to simple analytical pulses, optimal control theory (OCT) has been employed here to generate a suitable electric field to populate the target state/mode maximally. The complex OCT fields were analyzed by Husimi transformation, resolving the control field in time and energy. The adsorbate/surface systems investigated were CO/Cu(100), H/Si(100) and 2H/Ru(0001). These systems proved to be suitable models to study the above mentioned effects. Further, effects of temperature, pure dephasing (elastic scattering processes), pulse duration and dimensionality (up to four degrees of freedom) were studied. It was possible to selectively excite single vibrational modes, often even state-selective. Special processes like hot-band excitation, vibrationally mediated desorption and the excitation of "dark modes" were simulated. Finally, a novel OCT algorithm in density matrix representation has been developed which allows for time-dependent target operators and thus enables to control the excitation mechanism instead of only the final state. The algorithm is based on a combination of global (iterative) and local (non-iterative) OCT schemes, such that short, globally controlled time-intervals are coupled locally in time. Its numerical performance and accuracy were tested and verified and it was successfully applied to stabilize a two-state linear-combination and to enforce a successive "ladder climbing" in a rather harmonic system, where monochromatic, analytical pulses simultaneously excited several states, leading to a population loss in the target state.}, language = {en} } @phdthesis{HernandezGarcia2008, author = {Hernandez Garcia, Hugo Fernando}, title = {Multiscale simulation of heterophase polymerization : application to the synthesis of multicomponent colloidal polymer particles}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-25036}, school = {Universit{\"a}t Potsdam}, year = {2008}, abstract = {Heterophase polymerization is a technique widely used for the synthesis of high performance polymeric materials with applications including paints, inks, adhesives, synthetic rubber, biomedical applications and many others. Due to the heterogeneous nature of the process, many different relevant length and time scales can be identified. Each of these scales has a direct influence on the kinetics of polymerization and on the physicochemical and performance properties of the final product. Therefore, from the point of view of product and process design and optimization, the understanding of each of these relevant scales and their integration into one single model is a very promising route for reducing the time-to-market in the development of new products, for increasing the productivity and profitability of existing processes, and for designing products with improved performance or cost/performance ratio. The process considered is the synthesis of structured or composite polymer particles by multi-stage seeded emulsion polymerization. This type of process is used for the preparation of high performance materials where a synergistic behavior of two or more different types of polymers is obtained. Some examples include the synthesis of core-shell or multilayered particles for improved impact strength materials and for high resistance coatings and adhesives. The kinetics of the most relevant events taking place in an emulsion polymerization process has been investigated using suitable numerical simulation techniques at their corresponding time and length scales. These methods, which include Molecular Dynamics (MD) simulation, Brownian Dynamics (BD) simulation and kinetic Monte Carlo (kMC) simulation, have been found to be very powerful and highly useful for gaining a deeper insight and achieving a better understanding and a more accurate description of all phenomena involved in emulsion polymerization processes, and can be potentially extended to investigate any type of heterogeneous process. The novel approach of using these kinetic-based numerical simulation methods can be regarded as a complement to the traditional thermodynamic-based macroscopic description of emulsion polymerization. The particular events investigated include molecular diffusion, diffusion-controlled polymerization reactions, particle formation, absorption/desorption of radicals and monomer, and the colloidal aggregation of polymer particles. Using BD simulation it was possible to precisely determine the kinetics of absorption/desorption of molecular species by polymer particles, and to simulate the colloidal aggregation of polymer particles. For diluted systems, a very good agreement between BD simulation and the classical theory developed by Smoluchowski was obtained. However, for concentrated systems, significant deviations from the ideal behavior predicted by Smoluchowski were evidenced. BD simulation was found to be a very valuable tool for the investigation of emulsion polymerization processes especially when the spatial and geometrical complexity of the system cannot be neglected, as is the case of concentrated dispersions, non-spherical particles, structured polymer particles, particles with non-uniform monomer concentration, and so on. In addition, BD simulation was used to describe non-equilibrium monomer swelling kinetics, which is not possible using the traditional thermodynamic approach because it is only valid for systems at equilibrium. The description of diffusion-controlled polymerization reactions was successfully achieved using a new stochastic algorithm for the kMC simulation of imperfectly mixed systems (SSA-IM). In contrast to the traditional stochastic simulation algorithm (SSA) and the deterministic rate of reaction equations, instead of assuming perfect mixing in the whole reactor, the new SSA-IM determines the volume perfectly mixed between two consecutive reactions as a function of the diffusion coefficient of the reacting species. Using this approach it was possible to describe, using a single set of kinetic parameters, typical mass transfer limitations effects during a free radical batch polymerization such as the cage effect, the gel effect and the glass effect. Using multiscale integration it was possible to investigate the formation of secondary particles during the seeded emulsion polymerization of vinyl acetate over a polystyrene seed. Three different cases of radical generation were considered: generation of radicals by thermal decomposition of water-soluble initiating compounds, generation of radicals by a redox reaction at the surface of the particles, and generation of radicals by thermal decomposition of surface-active initiators "inisurfs" attached to the surface of the particles. The simulation results demonstrated the satisfactory reduction in secondary particles formation achieved when the locus of radical generation is controlled close to the particles surface.}, language = {en} } @phdthesis{Doyle2007, author = {Doyle, Timothy F.}, title = {The role of context in meaning and understanding}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-20691}, school = {Universit{\"a}t Potsdam}, year = {2007}, abstract = {In this work the concept of 'context' is considered in five main points. First, context is seen as always necessary for an adequate explication of the concepts of meaning and understanding. Context always plays a role and is not merely brought into consideration when handling a special class of statements or terms, or when there is doubt and clarification is necessary. Second, context cannot be completely reduced to some system of representation. The reason for this is the presence of humans, which is always an important component of a context. Humans experience situations in ways that are not always reducible to symbolic representation. Third, contexts are in principle open. In normal cases they cannot be determined or described in advance. A context is not to be equated with a set of information. Fourth, we understand the parameters of a context pragmatically, which is why we are not led into doubt or even to meaning skepticism by the open nature of a context. This pragmatic knowledge belongs to the category of an ability. Fifth, contexts are, in principle, accessible. This denies the idea that some contexts are incommensurable. There are a number of pragmatic ways of accessing unfamiliar contexts. Some of these are here examined in light of the so-called 'culture wars' in the U.S.A.}, language = {en} } @phdthesis{Ide2008, author = {Ide, Andreas Hans Peter}, title = {Self-Structuring of functionalized micro- and mesoporous organosilicas using boron-silane-precursors}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-23717}, school = {Universit{\"a}t Potsdam}, year = {2008}, abstract = {The structuring of porous silica materials at the nanometer scale and their surface functionalization are important issues of current materials research. Many innovations in chromatography, catalysis and electronic devices benefit from this knowledge. The work at hand is dedicated to the targeted design of functional organosilica materials. In this context a new precursor concept based on boron-silanes is presented. These precursors combine the properties of a structure directing group and a silica source by covalent borane linkage. Formation of the precursor is easily realized by a sequential two-step hydroboration, firstly on bis(triethoxysilyl)ethene, and secondly on an unsaturated structure directing moiety such as alkenes or polymers. The so prepared precursors self-organize when hydrolysis of their inorganic moiety takes place via an aggregation of their organic side chains into hydrophobic domains. In this way, the additional use of a surfactant as a template is not necessary. Chemical cleavage of these moieties (e.g. by ammonolysis or oxidative saponification) yields an organosilica where all functionalities are exclusively located at the pore wall and therefore accessible. The accessibility of the functionalities is a vital point for applications and is not necessarily granted for common silica functionalization approaches. Further advantages of the boron-silane concept are the possibility to introduce a variety of surface functionalities by heterolytic cleavage of the boron linker and the control of the pore morphology. For that purpose the covalent linkage of different alkyl groups and polymers was studied. Another aspect is the access to chiral boron silane precursors yielding functionalized mesoporous organosilica with chiral functionalities exclusively located at the pore walls after condensation and removal of the structure directing moiety. These materials possess great potential for applications documented by preliminary investigations on chiral resolution of a racemic mixture by HPLC and asymmetric catalysis. In the course of this work valuable insights into the targeted structuring and surface functionalization of organosilicas were gained. A promising outlook for further investigations is the extension of this concept by altering the structure directing moieties of the precursor. That way the morphology of the final organosilica might be controlled by for example mesogens. Furthermore, the use of the boron linker enables the introduction of multiple functionalities into organosilicas, making the obtained material unique in its performance.}, language = {en} } @phdthesis{Bahrke2008, author = {Bahrke, Sven}, title = {Mass spectrometric analysis of chitooligosaccharides and their interaction with proteins}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-20179}, school = {Universit{\"a}t Potsdam}, year = {2008}, abstract = {Chitooligosaccharides are composed of glycosamin and N-acetylglycisamin residues. Gel permeations chromatography is employed for the separation of oligomers, cation exchange chromatography is used for the separation of homologes and isomers. Trideuterioacetylation of the chitooligosaccharides followed by MALDI-TOF mass spectrometry allowes for the quantitation of mixtures of homologes. vMALDI LTQ multiple-stage MS is employed for quantitative sequencing of complex mixtures of heterochitooligosaccharides. Pure homologes and isomers are applied to biological assays. Chitooligosaccahrides form high-affinity non-covalent complexes with HC gp-39 (human cartilage glycoprotein of 39 kDa). The affinity of the chitooligosaccharides depends on DP, FA and the sequence of glycosamin and N-acetylglycosamin moieties. (+)nanoESI Q TOF MS/MS is used for identification of a high-affinity binding chitooligosaccharide of a non-covalent chitinase B - chitooligosaccharide complex. DADAA is identified as the heterochitoisomer binding with highest affinity and biostability to HC gp-39. Fluorescence based enzyme assays confirm the results.}, language = {en} } @phdthesis{Wrzus2008, author = {Wrzus, Cornelia}, title = {Similarity in personal relationships : associations with relationship regulation between and within individuals}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-20158}, school = {Universit{\"a}t Potsdam}, year = {2008}, abstract = {People engage in a multitude of different relationships. Relatives, spouses, and friends are modestly to moderately similar in various characteristics, e.g., personality characteristics, interests, appearance. The role of psychological (e.g., skills, global appraisal) and social (e.g., gender, familial status) similarities in personal relationships and the association with relationship quality (emotional closeness and reciprocity of support) were examined in four independent studies. Young adults (N = 456; M = 27 years) and middle-aged couples from four different family types (N = 171 couples, M = 38 years) gave answer to a computer-aided questionnaire regarding their ego-centered networks. A subsample of 175 middle-aged adults (77 couples and 21 individuals) participated in a one-year follow-up questioning. Two experimental studies (N = 470; N = 802), both including two assessments with an interval of five weeks, were conducted to examine causal relationships among similarity, closeness, and reciprocity expectations. Results underline the role of psychological and social similarities as covariates of emotional closeness and reciprocity of support on the between-relationship level, but indicate a relatively weak effect within established relationships. In specific relationships, such as parent-child relationships and friendships, psychological similarity partly alleviates the effects of missing genetic relatedness. Individual differences moderate these between-relationship effects. In all, results combine evolutionary and social psychological perspectives on similarity in personal relationships and extend previous findings by means of a network approach and an experimental manipulation of existing relationships. The findings further show that psychological and social similarity have different implications for the study of personal relationships depending on the phase in the developmental process of relationships.}, language = {en} } @misc{Meyer2007, type = {Master Thesis}, author = {Meyer, Eike}, title = {Democracy promotion by the European Union in Morocco within the framework of the European Neighbourhood Policy}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-19591}, school = {Universit{\"a}t Potsdam}, year = {2007}, abstract = {The intention of this master-thesis is a critical assessment of the European Union´s (EU) approach to external democracy promotion in Morocco. The study follows a comparative approach and compares the approach pursued by the EU within the framework of the European Neighbourhood Policy (ENP), incepted in 2004, with the approach that it had developed up until then under the framework of the Euro-Mediterranean Partnership (EMP). The comparison is done with the intention to analyse, to what degree it is justified to speak of a new impetus for democratisation through the ENP in partner countries. The analysis takes into consideration the range of possible instruments for external democracy promotion in the categories „diplomacy", „conditionality" and „positive instruments". For the comparison of democracy promotion under the EMP and the ENP it is suggested to compare the implemented measures in respect to three distinct dimensions: As a first dimension, instruments of democracy promotion are analysed with respect to the focus on indirect vs. direct instruments, e.g. those which aim at establishing socio-economic preconditions favourable to successful democratisation, vs. those which immediately intervene in the processes of political reform. As a second dimension, it is asked whether there has been a shift in the democracy promotion approach on a continuum between consensual cooptation and coercive intervention. As a third dimension, finally, it is analysed whether the approach has undergone a general intensification of efforts, e.g. whether the approach to democracy promotion has become a more active one. The analysis in this master-thesis comes to the conclusion that since the inception of the ENP the EU is indeed pursuing a slightly more direct and certainly a more active approach to democracy promotion in Morocco, while no significant change can be observed in comparison to the strictly partnership-oriented and consensual approach of the EMP. It can be argued that, under the ENP, relations to Morocco have indeed become somewhat more "political", although at the same time they are still not pro-actively oriented at a political liberalisation of the political regime. Reforms promoted by the EU in Morocco are modest and largely in line with the reform agenda of the Morrocan government itself - e.g. a still largely authoritarian monarchy. Concrete reform steps directed at an opening of the political space, which is largely reserved to the king and its administration, are neither demanded nor supported by democracy promotion instruments, also under the ENP.}, language = {en} } @phdthesis{Muschalla2008, author = {Muschalla, Beate}, title = {Workplace-related anxieties and workplace phobia : a concept of domain-specific mental disorders}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-20048}, school = {Universit{\"a}t Potsdam}, year = {2008}, abstract = {Background: Anxiety in the workplace is a special problem as workplaces are especially prone to provoke anxiety: There are social hierarchies, rivalries between colleagues, sanctioning through superiors, danger of accidents, failure, and worries of job security. Workplace phobia is a phobic anxiety reaction with symptoms of panic occurring when thinking of or approaching the workplace, and with clear tendency of avoidance. Objectives: What characterizes workplace-related anxieties and workplace phobia as domain-specific mental disorders in contrast to conventional anxiety disorders? Method: 230 patients from an inpatient psychosomatic rehabilitation center were interviewed with the (semi-)structured Mini-Work-Anxiety-Interview and the Mini International Neuropsychiatric Interview, concerning workplace-related anxieties and conventional mental disorders. Additionally, the patients filled in the self-rating questionnaires Job-Anxiety-Scale (JAS) and the Symptom Checklist (SCL-90-R)measuring job-related and general psychosomatic symptom load. Results: Workplace-related anxieties occurred together with conventional anxiety disorders in 35\% of the patients, but also alone in others (23\%). Workplace phobia could be found in 17\% of the interviewed, any diagnosis of workplace-related anxiety was stated in 58\%. Workplace phobic patients had significantly higher scores in job-anxiety than patients without workplace phobia. Patients with workplace phobia were significantly longer on sick leave in the past 12 months (23,5 weeks) than patients without workplace phobia (13,4 weeks). Different qualities of workplace-related anxieties lead with different frequencies to work participation disorders. Conclusion: Workplace phobia cannot be described by only assessing the general level of psychosomatic symptom load and conventional mental disorders. Workplace-related anxieties and workplace phobia have an own clinical value which is mainly defined by specific workplace-related symptom load and work-participation disorders. They require special therapeutic attention and treatment instead of a "sick leave" certification by the general health physician. Workplace phobia should be named with a proper diagnosis according to ICD-10 chapter V, F 40.8: "workplace phobia".}, language = {en} } @misc{Trapp2007, type = {Master Thesis}, author = {Trapp, Matthias}, title = {Analysis and exploration of virtual 3D city models using 3D information lenses}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-13930}, school = {Universit{\"a}t Potsdam}, year = {2007}, abstract = {This thesis addresses real-time rendering techniques for 3D information lenses based on the focus \& context metaphor. It analyzes, conceives, implements, and reviews its applicability to objects and structures of virtual 3D city models. In contrast to digital terrain models, the application of focus \& context visualization to virtual 3D city models is barely researched. However, the purposeful visualization of contextual data of is extreme importance for the interactive exploration and analysis of this field. Programmable hardware enables the implementation of new lens techniques, that allow the augmentation of the perceptive and cognitive quality of the visualization compared to classical perspective projections. A set of 3D information lenses is integrated into a 3D scene-graph system: • Occlusion lenses modify the appearance of virtual 3D city model objects to resolve their occlusion and consequently facilitate the navigation. • Best-view lenses display city model objects in a priority-based manner and mediate their meta information. Thus, they support exploration and navigation of virtual 3D city models. • Color and deformation lenses modify the appearance and geometry of 3D city models to facilitate their perception. The presented techniques for 3D information lenses and their application to virtual 3D city models clarify their potential for interactive visualization and form a base for further development.}, language = {en} } @phdthesis{Gebauer2008, author = {Gebauer, Denis}, title = {A novel view on the early stage of crystallization}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-19818}, school = {Universit{\"a}t Potsdam}, year = {2008}, abstract = {This thesis provides a novel view on the early stage of crystallization utilizing calcium carbonate as a model system. Calcium carbonate is of great economical, scientific and ecological importance, because it is a major part of water hardness, the most abundant Biomineral and forms huge amounts of geological sediments thus binding large amounts of carbon dioxide. The primary experiments base on the evolution of supersaturation via slow addition of dilute calcium chloride solution into dilute carbonate buffer. The time-dependent measurement of the Ca2+ potential and concurrent pH = constant titration facilitate the calculation of the amount of calcium and carbonate ions bound in pre-nucleation stage clusters, which have never been detected experimentally so far, and in the new phase after nucleation, respectively. Analytical Ultracentrifugation independently proves the existence of pre-nucleation stage clusters, and shows that the clusters forming at pH = 9.00 have a proximately time-averaged size of altogether 70 calcium and carbonate ions. Both experiments show that pre-nucleation stage cluster formation can be described by means of equilibrium thermodynamics. Effectively, the cluster formation equilibrium is physico-chemically characterized by means of a multiple-binding equilibrium of calcium ions to a 'lattice' of carbonate ions. The evaluation gives GIBBS standard energy for the formation of calcium/carbonate ion pairs in clusters, which exhibits a maximal value of approximately 17.2 kJ mol^-1 at pH = 9.75 and relates to a minimal binding strength in clusters at this pH-value. Nucleated calcium carbonate particles are amorphous at first and subsequently become crystalline. At high binding strength in clusters, only calcite (the thermodynamically stable polymorph) is finally obtained, while with decreasing binding strength in clusters, vaterite (the thermodynamically least stable polymorph) and presumably aragonite (the thermodynamically intermediate stable polymorph) are obtained additionally. Concurrently, two different solubility products of nucleated amorphous calcium carbonate (ACC) are detected at low binding strength and high binding strength in clusters (ACC I 3.1EE-8 M^2, ACC II 3.8EE-8 M^2), respectively, indicating the precipitation of at least two different ACC species, while the clusters provide the precursor species of ACC. It is proximate that ACC I may relate to calcitic ACC -i.e. ACC exhibiting short range order similar to the long range order of calcite and that ACC II may relate to vateritic ACC, which will subsequently transform into the particular crystalline polymorph as discussed in the literature, respectively. Detailed analysis of nucleated particles forming at minimal binding strength in clusters (pH = 9.75) by means of SEM, TEM, WAXS and light microscopy shows that predominantly vaterite with traces of calcite forms. The crystalline particles of early stages are composed of nano-crystallites of approximately 5 to 10 nm size, respectively, which are aligned in high mutual order as in mesocrystals. The analyses of precipitation at pH = 9.75 in presence of additives -polyacrylic acid (pAA) as a model compound for scale inhibitors and peptides exhibiting calcium carbonate binding affinity as model compounds for crystal modifiers- shows that ACC I and ACC II are precipitated in parallel: pAA stabilizes ACC II particles against crystallization leading to their dissolution for the benefit of crystals that form from ACC I and exclusively calcite is finally obtained. Concurrently, the peptide additives analogously inhibit the formation of calcite and exclusively vaterite is finally obtained in case of one of the peptide additives. These findings show that classical nucleation theory is hardly applicable for the nucleation of calcium carbonate. The metastable system is stabilized remarkably due to cluster formation, while clusters forming by means of equilibrium thermodynamics are the nucleation relevant species and not ions. Most likely, the concept of cluster formation is a common phenomenon occurring during the precipitation of hardly soluble compounds as qualitatively shown for calcium oxalate and calcium phosphate. This finding is important for the fundamental understanding of crystallization and nucleation-inhibition and modification by additives with impact on materials of huge scientific and industrial importance as well as for better understanding of the mass transport in crystallization. It can provide a novel basis for simulation and modelling approaches. New mechanisms of scale formation in Bio- and Geomineralization and also in scale inhibition on the basis of the newly reported reaction channel need to be considered.}, language = {en} } @phdthesis{Fischer2008, author = {Fischer, Anna}, title = {"Reactive hard templating" : from carbon nitrides to metal nitrides}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-19777}, school = {Universit{\"a}t Potsdam}, year = {2008}, abstract = {Nanostructured inorganic materials are routinely synthesized by the use of templates. Depending on the synthesis conditions of the product material, either "soft" or "hard" templates can be applied. For sol-gel processes, usually "soft" templating techniques are employed, while "hard" templates are used for high temperature synthesis pathways. In classical templating approaches, the template has the unique role of structure directing agent, in the sense that it is not participating to the chemical formation of the resulting material. This work investigates a new templating pathway to nanostructured materials, where the template is also a reagent in the formation of the final material. This concept is described as "reactive templating" and opens a synthetic path toward materials which cannot be synthesised on a nanometre scale by classical templating approaches. Metal nitrides are such kind of materials. They are usually produced by the conversion of metals or metal oxides in ammonia flow at high temperature (T > 1000°C), which make the application of classical templating techniques difficult. Graphitic carbon nitride, g-C3N4, despite its fundamental and theoretical importance, is probably one of the most promising materials to complement carbon in material science and many efforts are put in the synthesis of this material. A simple polyaddition/elimination reaction path at high temperature (T = 550°C) allows the polymerisation of cyanamide toward graphitic carbon nitride solids. By hard templating, using nanostructured silica or aluminium oxide as nanotemplates, a variety of nanostructured graphitic carbon nitrides such as nanorods, nanotubes, meso- and macroporous powders could be obtained by nanocasting or nanocoating. Due to the special semi-conducting properties of the graphitic carbon nitride matrix, the nanostructured graphitic carbon nitrides show unexpected catalytic activity for the activation of benzene in Friedel-Crafts type reactions, making this material an interesting metal free catalyst. Furthermore, due to the chemical composition of g-C3N4 and the fact that it is totally decomposed at temperatures between 600°C and 800°C even under inert atmosphere, g-C3N4 was shown to be a good nitrogen donor for the synthesis of early transition metal nitrides at high temperatures. Thus using the nanostructured carbon nitrides as "reactive templates" or "nanoreactors", various metal nitride nanostructures, such as nanoparticles and porous frameworks could be obtained at high temperature. In this approach the carbon nitride nanostructure played both the role of the nitrogen source and of the exotemplate, imprinting its size and shape to the resulting metal nitride nanostructure.}, language = {en} } @phdthesis{Imranulhaq2008, author = {Imran ul-haq, Muhammad}, title = {Synthesis of fluorinated polymers in supercritical carbon dioxide (scCO₂)}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-19868}, school = {Universit{\"a}t Potsdam}, year = {2008}, abstract = {For the first time stabilizer-free vinylidene fluoride (VDF) polymerizations were carried out in homogeneous phase with supercritical CO₂. Polymerizations were carried out at 140°C, 1500 bar and were initiated with di-tert-butyl peroxide (DTBP). In-line FT-NIR (Fourier Transform- Near Infrared) spectroscopy showed that complete monomer conversion may be obtained. Molecular weights were determined via size-exclusion chromatography (SEC) and polymer end group analysis by 1H-NMR spectroscopy. The number average molecular weights were below 104 g∙mol-1 and polydispersities ranged from 3.1 to 5.7 depending on DTBP and VDF concentration. To allow for isothermal reactions high CO₂ contents ranging from 61 to 83 wt.\% were used. The high-temperature, high-pressure conditions were required for homogeneous phase polymerization. These conditions did not alter the amount of defects in VDF chaining. Scanning electron microscopy (SEM) indicated that regular stack-type particles were obtained upon expansion of the homogeneous polymerization mixture. To reduce the required amount of initiator, further VDF polymerizations using chain transfer agents (CTAs) to control molecular weights were carried out in homogeneous phase with supercritical carbon dioxide (scCO₂) at 120 °C and 1500 bar. Using perfluorinated hexyl iodide as CTA, polymers of low polydispersity ranging from 1.5 to 1.2 at the highest iodide concentration of 0.25 mol·L-1 were obtained. Electrospray ionization- mass spectroscopy (ESI-MS) indicates the absence of initiator derived end groups, supporting livingness of the system. The "livingness" is based on the labile C-I bond. However, due to the weakness of the C-I bond perfluorinated hexyl iodide also contributes to initiation. To allow for kinetic analyses of VDF polymerizations the CTA should not contribute to initiation. Therefore, additional CTAs were applied: BrCCl3, C6F13Br and C6F13H. It was found that C6F13H does not contribute to initiation. At 120°C and 1500 bar kp/kt0.5~ 0.64 (L·mol-1·s-1)0.5 was derived. The chain transfer constant (CT) at 120°C has been determined to be 8·10-1, 9·10-2 and 2·10-4 for C6F13I, C6F13Br and C6F13H, respectively. These CT values are associated with the bond energy of the C-X bond. Moreover, the labile C-I bond allows for functionalization of the polymer to triazole end groups applying click reactions. After substitution of the iodide end group by an azide group 1,3 dipolar cycloadditions with alkynes yield polymers with 1,2,3 triazole end groups. Using symmetrical alkynes the reactions may be carried out in the absence of any catalyst. This end-functionalized poly (vinylidene fluoride) (PVDF) has higher thermal stability as compared to the normal PVDF. PVDF samples from homogeneous phase polymerizations in supercritical CO₂ and subsequent expansion to ambient conditions were analyzed with respect to polymer end groups, crystallinity, type of polymorphs and morphology. Upon expansion the polymer was obtained as white powder. Scanning electron microscopy (SEM) showed that DTBP derived polymer end groups led to stack-type particles whereas sponge- or rose-type particles were obtained in case of CTA fragments as end groups. Fourier-Transform Infrared spectroscopy and wide angle X-ray diffraction indicated that the type of polymorph, α or β crystal phase was significantly affected by the type of end group. The content of β-phase material, which is responsible for piezoelectricity of PVDF, is the highest for polymer with DTBP-derived end groups. In addition, the crystallinity of the material, as determined via differential scanning calorimetry is affected by the end groups and polymer molecular weights. For example, crystallinity ranges from around 26 \% for DTBP-derived end groups to a maximum of 62 \% for end groups originating from perfluorinated hexyl iodide for polymers with Mn ~2200 g·mol-1. Expansion of the homogeneous polymerization mixture results in particle formation by a non-optimized RESS (Rapid Expansion from Supercritical Solution) process. Thus, it was tested how polymer end groups affect the particles size distribution obtained from RESS process under controlled conditions (T = 50°C and P = 200 bar). In all RESS experiments, small primary PVDF with diameters less than 100 nm without the use of liquid solvents, surfactants, or other additives were produced. A strong correlation between particle size and particle size distribution with polymer end groups and molecular weight of the original material was observed. The smallest particles were found for RESS of PVDF with Mn~ 4000 g·mol-1 and PFHI (C6F13I) - derived end groups.}, language = {en} } @phdthesis{Rehak2008, author = {Rehak, Katrin}, title = {Pliocene-Pleistocene landscape evolution in south-central Chile : interactions between tectonic, geomorphic, and climatic processes}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-19793}, school = {Universit{\"a}t Potsdam}, year = {2008}, abstract = {Landscapes evolve in a complex interplay between climate and tectonics. Thus, the geomorphic characteristics of a landscape can only be understood if both, climatic and tectonic signals of past and ongoing processes can be identified. In order to evaluate the impact of both forcing factors it is crucial to quantify the evolution of geomorphic markers in natural environments. The Cenozoic Andes are an ideal setting to evaluate tectonic and climatic aspects of landscape evolution at different time and length scales in different natural compartments. The Andean Cordillera constitutes the type subduction orogen and is associated with the subduction of the oceanic Nazca Plate beneath the South American continent since at least 200 million years. In Chile and the adjacent regions this convergent margin is characterized by active tectonics, volcanism, and mountain building. Importantly, along the coast of Chile megathrust earthquakes occur frequently and influence landscape evolution. In fact, the largest earthquake ever recorded occurred in south-central Chile in 1960 and comprised a rupture zone of ~ 1000 km length. However, on longer time scales beyond historic documentation of seismicity it is not well known, how such seismotectonic segments have behaved and how they influence the geomorphic evolution of the coastal realms. With several semi-independent morphotectonic segments, recurrent megathrust earthquakes, and a plethora of geomorphic features indicating sustained tectonism, the margin of Chile is thus a key area to study relationships between surface processes and tectonics. In this study, I combined geomorphology, geochronology, sedimentology, and morphometry to quantify the Pliocene-Pleistocene landscape evolution of the tectonically active south-central Chile forearc. Thereby, I provide (1) new results about the influence of seismotectonic forearc segmentation on the geomorphic evolution and (2) new insights in the interaction between climate and tectonics with respect to the morphology of the Chilean forearc region. In particular, I show that the forearc is characterized by three long-term segments that are not correlated with short-lived earthquake-rupture zones that may. These segments are the Nahuelbuta, Tolt{\´e}n, and Bueno segments, each recording a distinct geomorphic and tectonic evolution. The Nahuelbuta and Bueno segments are undergoing active tectonic uplift. The long-term behavior of these two segments is manifested in form of two doubly plunging, growing antiforms that constitute an integral part of the Coastal Cordillera and record the uplift of marine and river terraces. In addition, these uplifting areas have caused major changes in flow directions or rivers. In contrast, the Tolt{\´e}n segment, situated between the two other segments, appears to be quasi-stable. In order to further quantify uplift and incision in the actively deforming Nahuelbuta segment, I dated an erosion surface and fluvial terraces in the Coastal Cordillera with cosmogenic 10Be and 26Al and optically stimulated luminescence, respectively. According to my results, late Pleistocene uplift rates corresponding to 0.88 mm a-1 are faster than surface-uplift rates averaging over the last 5 Ma, which are in the range of 0.21 mm a-1. This discrepancy suggests that surface uplift is highly variable in time and space and might preferably concentrate along reverse faults as indicated by a late Pleistocene flow reversal. In addition, the results of exposure dating with cosmogenic 10Be and 26Al indicate that the morphotectonic segmentation of this region of the forearc has been established in Pliocene time, coeval with the initiation of uplift of the Coastal Cordillera about 5 Ma ago, inferred to be related to a shift in subduction mode from erosion to accretion. Finally, I dated volcanic clasts obtained from alluvial surfaces in the Central Depression, a low-relief sector separating the Coastal from the Main Cordillera, with stable cosmogenic 3He and 21Ne, in order to reveal the controls of sediment accumulation in the forearc. My results document that these gently sloping surfaces have been deposited 150 to 300 ka ago. This deposition may be related to changes in the erosional regime during glacial episodes. Taken together, the data indicates that the overall geomorphic expression of the forearc is of post-Miocene age and may be intimately related to a climatic overprint of the tectonic system. This climatic forcing is also reflected in the topography and local relief of the Central and Southern Andes that vary considerably along the margin, determined by the dominant surface process that in turn is eventually controlled by climate. However, relief also partly reflects surface processes that have taken place under past climatic conditions. This emphasizes that due care has to be exercised when interpreting landscapes as mirrors of modern climates.}, language = {en} } @misc{Paun2007, type = {Master Thesis}, author = {Paun, Christopher}, title = {Democratization and police reform}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-19487}, school = {Universit{\"a}t Potsdam}, year = {2007}, abstract = {This paper compares police reforms during democratization in Poland, Hungary, and Bosnia-Herzegovina. It analyses the changes to the structure of the democratic control of the police in each reform, paying special attention to the decentralization versus centralization aspect of it. The research question of this paper is: Why are some states decentralizing the democratic control of the police, while others are centralizing it, both with the aim of democratization? The theoretical background of this study are theories about policy diffusion and policy transfer. Therefore this study can be categorized as part of two different research areas. On the one hand, it is a paper from the discipline of International Relations. On the other hand, it is a paper from the discipline of Comparative Politics. The combined attention to international and national factors influencing police reform is reflected by the structure of this paper. Chapter 3 examines police structures and police reforms in established democracies as possible role models for new democracies. Chapter 4 looks at international and transnational actors that actively try to influence police reform. After having examined these external factors, three cases of police reform in new democracies are examined in chapter 5.}, language = {en} } @phdthesis{Lantuit2008, author = {Lantuit, Hugues}, title = {The modification of arctic permafrost coastlines}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-19732}, school = {Universit{\"a}t Potsdam}, year = {2008}, abstract = {The arctic region is undergoing the most rapid environmental change experienced on Earth, and the rate of change is expected to increase over the coming decades. Arctic coasts are particularly vulnerable because they lie at the interface between terrestrial systems dominated by permafrost and marine systems dominated by sea ice. An increased rise in sea level and degradation of sea-ice as predicted by the Intergovernmental Panel on Climate Change in its most recent report and as observed recently in the Arctic will likely result in greater rates of coastal retreat. An increase in coastal erosion would result in dramatic increases in the volume of sediment, organic carbon and contaminants to the Arctic Ocean. These in turn have the potential to create dramatic changes in the geochemistry and biodiversity of the nearshore zone and affect the Arctic Ocean carbon cycle. To calculate estimates of organic carbon input from coastal erosion to the Arctic Ocean, current methods rely on the length of the coastline in the form of non self-similar line datasets. This thesis however emphasizes that using shorelines drawn at different scales can induce changes in the amount of sediment released by 30\% in some cases. It proposes a substitute method of computations of erosion based on areas instead of lengths (i.e. buffers instead of shoreline lengths) which can be easily implemented at the circum-Arctic scale. Using this method, variations in quantities of eroded sediment are, on average, 70\% less affected by scale changes and are therefore a more reliable method of calculation. Current estimates of coastal erosion rates in the Arctic are scarce and long-term datasets are a handful, which complicates assessment and prognosis of coastal processes, in particular the occurrence of coastal hazards. This thesis aims at filling the gap by providing the first long-term dataset (1951-2006) of coastal erosion on the Bykovsky Peninsula, North-East Siberia. This study shows that the coastline, which is made of ice-rich permafrost, retreated at a mean annual rate of 0.59 m/yr between 1951and 2006. Rates were highly variable: 97.0 \% of the rates observed were less than 2 m/yr and 81.6\% were less than 1m/yr. However, no significant trend in erosion could be recorded despite the study of five temporal subperiods within 1951-2006. The juxtaposition of wind records could not help to explain erosion records either and this thesis emphasizes the local controls on erosion, in particular the cryostratigraphy, the proximity of the Peninsula to the Lena River Delta freshwater plume and the local topographical constraints on swell development. On ice-rich coastal stretches of the Artic, the interaction of coastal dynamics and permafrost leads to the occurrence of spectacular "C-shaped" depressions termed retrogressive thaw slumps which can reach lengths of up to 650 m. On Herschel Island and at King Point (Yukon Coastal Plain, northern Canada), topographical, sedimentological and biogeochemical surveys were conducted to investigate the present and past activity of these landforms. In particular, undisturbed tundra areas were compared with zones of former slump activity, now stabilized and re-vegetated. This thesis shows that stabilized areas are drier and less prone to plant growth than undisturbed areas and feature fundamentally different geotechnical properties. Radiocarbon dating and topographical surveys indicated until up to 300 BP a likely period of dramatic slump activity on Herschel Island, similar to the one currently observed, which led to the creation of these surfaces. This thesis hypothesizes the occurrence of a ~250 years cycle of slump activity on the Herschel Island shoreline based on the surveyed topography and cryostratigraphy and anticipates higher frequency of slump activity in the future. The variety of processes described in this thesis highlights the changing nature of the intensity and frequency of physical processes acting upon the arctic coast. It also challenges current perceptions of the threats to existing industry and community infrastructure in the Arctic. The increasing presence of humans on Artic coasts coupled with the expected development of shipping will drive an increase in economical and industrial activity on these coasts which remains to be addressed scientifically.}, language = {en} } @article{Fanselow2007, author = {Fanselow, Gisbert}, title = {The restricted access of information structure to syntax}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-19713}, year = {2007}, abstract = {This paper sketches the view that syntax does not directly interact with information structure. Therefore, syntactic data are of little help when one wants to narrow down the interpretation of terms such as "focus", "topic", etc.}, language = {en} } @article{Fery2007, author = {F{\´e}ry, Caroline}, title = {Information structural notions and the fallacy of invariant correlates}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-19692}, year = {2007}, abstract = {In a first step, definitions of the irreducible information structural categories are given, and in a second step, it is shown that there are no invariant phonological or otherwise grammatical correlates of these categories. In other words, the phonology, syntax or morphology are unable to define information structure. It is a common mistake that information structural categories are expressed by invariant grammatical correlates, be they syntactic, morphological or phonological. It is rather the case that grammatical cues help speaker and hearer to sort out which element carries which information structural role, and only in this sense are the grammatical correlates of information structure important. Languages display variation as to the role of grammar in enhancing categories of information structure, and this variation reflects the variation found in the 'normal' syntax and phonology of languages.}, language = {en} } @article{EndrissHinterwimmer2007, author = {Endriss, Cornelia and Hinterwimmer, Stefan}, title = {Direct and indirect aboutness topics}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-19640}, year = {2007}, abstract = {We propose a definition of aboutness topicality that not only encompasses individual denoting DPs, but also indefinites. We concentrate on the interpretative effects of marking indefinites as topics: they either receive widest scope in their clause, or they are interpreted in the restrictor of an overt or covert Q-adverb. We show that in the first case they are direct aboutness topics insofar as they are the subject of a predication expressed by the comment, while in the second case they are indirect aboutness topics: they define the subject of a higher-order predication - namely the set of situations that the respective Q-adverb quantifies over.}, language = {en} } @article{Kasimir2006, author = {Kasimir, Elke}, title = {On 'nicht...sondern...' (contrastive 'not...but...')}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-19537}, year = {2006}, abstract = {This article presents an analysis of German nicht...sondern... (contrastive not...but...) which departs from the commonly held view that this construction should be explained by appeal to its alleged corrective function. It will be demonstrated that in nicht A sondern B (not A but B), A and B just behave like stand-alone unmarked answers to a common question Q, and that this property of sondern is presuppositional in character. It is shown that from this general observation many interesting properties of nicht...sondern... follow, among them distributional differences between German 'sondern' and German 'aber' (contrastive but, concessive but), intonational requirements and exhaustivity effects. sondern's presupposition is furthermore argued to be the result of the conventionalization of conversational implicatures.}, language = {en} } @article{vandeVijverSennemaZimmer–Stahl2006, author = {van de Vijver, Ruben and Sennema, Anke and Zimmer-Stahl, Anne}, title = {An analysis of pitch and duration in material used to test L2 processing of words}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-19583}, year = {2006}, abstract = {The material reported on in this paper is part of a set of experiments in which the role of Information Structure on L2 processing of words is tested. Pitch and duration of 4 sets of experimental material in German and English are measured and analyzed in this paper. The well-known finding that accent boosts duration and pitch is confirmed. Syntactic and lexical means of marking focus, however, do not give the duration and the pitch of a word an extra boost.}, language = {en} } @article{SchmitzHoehleMuelleretal.2006, author = {Schmitz, Michaela and H{\"o}hle, Barbara and M{\"u}ller, Anja and Weissenborn, J{\"u}rgen}, title = {The recognition of the prosodic focus position in German-learning infants from 4 to 14 months}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-19566}, year = {2006}, abstract = {The aim of the present study was to elucidate in a study with 4-, 6-, 8-, and 14-month-old German-learning children, when and how they may acquire the regularities which underlie Focus-to-Stress Alignment (FSA) in the target language, that is, how prosody is associated with specific communicative functions. Our findings suggest, that 14-month-olds have already found out that German allows for variable focus positions, after having gone through a development which goes from a predominantly prosodically driven processing of the input to a processing where prosody interacts more and more with the growing lexical and syntactic knowledge of the child.}, language = {en} } @article{EndrissHinterwimmer2006, author = {Endriss, Cornelia and Hinterwimmer, Stefan}, title = {Quantificational Variability Effects with plural definites}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-19512}, year = {2006}, abstract = {In this paper we compare the behaviour of adverbs of frequency (de Swart 1993) like usually with the behaviour of adverbs of quantity like for the most part in sentences that contain plural definites. We show that sentences containing the former type of Q-adverb evidence that Quantificational Variability Effects (Berman 1991) come about as an indirect effect of quantification over situations: in order for quantificational variability readings to arise, these sentences have to obey two newly observed constraints that clearly set them apart from sentences containing corresponding quantificational DPs, and that can plausibly be explained under the assumption that quantification over (the atomic parts of) complex situations is involved. Concerning sentences with the latter type of Q-adverb, on the other hand, such evidence is lacking: with respect to the constraints just mentioned, they behave like sentences that contain corresponding quantificational DPs. We take this as evidence that Q-adverbs like for the most part do not quantify over the atomic parts of sum eventualities in the cases under discussion (as claimed by Nakanishi and Romero (2004)), but rather over the atomic parts of the respective sum individuals.}, language = {en} } @article{HellmuthSkopeteas2007, author = {Hellmuth, Sam and Skopeteas, Stavros}, title = {Information structure in linguistic theory and in speech production : validation of a Cross-Linguistic data set}, publisher = {Universit{\"a}tsverlag Potsdam}, address = {Potsdam}, isbn = {978-3-939469-72-8}, issn = {1866-4725}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-19450}, pages = {141 -- 186}, year = {2007}, abstract = {The aim of this paper is to validate a dataset collected by means of production experiments which are part of the Questionnaire on Information Structure. The experiments generate a range of information structure contexts that have been observed in the literature to induce specific constructions. This paper compares the speech production results from a subset of these experiments with specific claims about the reflexes of information structure in four different languages. The results allow us to evaluate and in most cases validate the efficacy of our elicitation paradigms, to identify potentially fruitful avenues of future research, and to highlight issues involved in interpreting speech production data of this kind.}, language = {en} } @article{KueglerSkopeteasVerhoeven2007, author = {K{\"u}gler, Frank and Skopeteas, Stavros and Verhoeven, Elisabeth}, title = {Encoding information structure in Yucatec Maya}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-19469}, year = {2007}, abstract = {The aim of this paper is to outline the means for encoding information structure in Yucatec Maya. Yucatec Maya is a tone language, displaying a three-fold opposition in the tonal realization of syllables. From the morpho-syntactic point of view, the grammar of Yucatec Maya contains morphological (topic affixes, morphological marking of out-of-focus predicates) and syntactic (designated positions) means to uniquely specify syntactic constructions for their information structure. After a descriptive overview of these phenomena, we present experimental evidence which reveals the impact of the nonavailability of prosodic alternatives on the choice of syntactic constructions in language production.}, language = {en} }