@phdthesis{Konon2018, author = {Konon, Alexander}, title = {Essays on career choice under risk and ambiguity}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-416466}, school = {Universit{\"a}t Potsdam}, pages = {x, 250, xxxv}, year = {2018}, abstract = {This dissertation consists of five self-contained essays, addressing different aspects of career choices, especially the choice of entrepreneurship, under risk and ambiguity. In Chapter 2, the first essay develops an occupational choice model with boundedly rational agents, who lack information, receive noisy feedback, and are restricted in their decisions by their personality, to analyze and explain puzzling empirical evidence on entrepreneurial decision processes. In the second essay, in Chapter 3, I contribute to the literature on entrepreneurial choice by constructing a general career choice model on the basis of the assumption that outcomes are partially ambiguous. The third essay, in Chapter 4, theoretically and empirically analyzes the impact of media on career choices, where information on entrepreneurship provided by the media is treated as an informational shock affecting prior beliefs. The fourth essay, presented in Chapter 5, contains an empirical analysis of the effects of cyclical macro variables (GDP and unemployment) on innovative start-ups in Germany. In the fifth, and last, essay in Chapter 6, we examine whether information on personality is useful for advice, using the example of career advice.}, language = {en} } @phdthesis{Wulff2018, author = {Wulff, Alexander}, title = {Essays in macroeconomics and financial market imperfections}, doi = {10.25932/publishup-42995}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-429956}, school = {Universit{\"a}t Potsdam}, pages = {X, 142}, year = {2018}, abstract = {This dissertation consists of four self-contained papers that deal with the implications of financial market imperfections and heterogeneity. The analysis mainly relates to the class of incomplete-markets models but covers different research topics. The first paper deals with the distributional effects of financial integration for developing countries. Based on a simple heterogeneous-agent approach, it is shown that capital owners experience large welfare losses while only workers moderately gain due to higher wages. The large welfare losses for capital owners contrast with the small average welfare gains from representative-agent economies and indicate that a strong opposition against capital market opening has to be expected. The second paper considers the puzzling observation of capital flows from poor to rich countries and the accompanying changes in domestic economic development. Motivated by the mixed results from the literature, we employ an incomplete-markets model with different types of idiosyncratic risk and borrowing constraints. Based on different scenarios, we analyze under what conditions the presence of financial market imperfections contributes to explain the empirical findings and how the conditions may change with different model assumptions. The third paper deals with the interplay of incomplete information and financial market imperfections in an incomplete-markets economy. In particular, it analyzes the impact of incomplete information about idiosyncratic income shocks on aggregate saving. The results show that the effect of incomplete information is not only quantitatively substantial but also qualitatively ambiguous and varies with the influence of the income risk and the borrowing constraint. Finally, the fourth paper analyzes the influence of different types of fiscal rules on the response of key macroeconomic variables to a government spending shock. We find that a strong temporary increase in public debt contributes to stabilizing consumption and leisure in the first periods following the change in government spending, whereas a non-debt-intensive fiscal rule leads to a faster recovery of consumption, leisure, capital and output in later periods. Regarding optimal debt policy, we find that a debt-intensive fiscal rule leads to the largest aggregate welfare benefit and that the individual welfare gain is particularly high for wealth-poor agents.}, language = {en} } @phdthesis{Grunert2018, author = {Grunert, Bianca}, title = {Entwicklung von Markierungsreagenzien f{\"u}r die bildgebende Diagnostik}, doi = {10.25932/publishup-42283}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-422830}, school = {Universit{\"a}t Potsdam}, pages = {155}, year = {2018}, abstract = {Die intrazellul{\"a}re Markierung mit geeigneten Reagenzien erm{\"o}glicht ihre bildgebende Darstellung in lebenden Organismen. Dieses Verfahren (auch „Zell-Tracking" genannt) wird in der Grundlagenforschung zur Entwicklung zellul{\"a}rer Therapien, f{\"u}r die Erforschung pathologischer Prozesse, wie der Metastasierung, sowie f{\"u}r Therapiekontrollen eingesetzt. Besondere Bedeutung haben in den letzten Jahren zellul{\"a}re Therapien mit Stammzellen erlangt, da sie großes Potential bei der Regeneration von Geweben bei Krankheiten wie Morbus Parkinson oder Typ-1-Diabetes versprechen. F{\"u}r die Entwicklung einer zellul{\"a}ren Therapie sind Informationen {\"u}ber den Verbleib der applizierten Zellen in vivo (Homing-Potential), {\"u}ber ihre Zellphysiologie sowie {\"u}ber die Entstehung m{\"o}glicher Entz{\"u}ndungen notwendig. Das Ziel der vorliegenden Arbeit war daher die Synthese von Markierungsreagenzien, die nicht nur eine effiziente Zellmarkierung erm{\"o}glichen, sondern einen synergistischen Effekt hinsichtlich des modalit{\"a}ts{\"u}bergreifenden Einsatzes in den bildgebenden Verfahren MRT und Laser-Ablation(LA)-ICP-MS erlauben. Die MRT-Bildgebung erm{\"o}glicht die nicht invasive Nachverfolgung markierter Zellen in vivo und die LA-ICP-MS die anschließende ex vivo Analytik zur Darstellung der Elementverteilung (Bioimaging) in einer Biopsieprobe oder in einem Gewebeschnitt. F{\"u}r diese Zwecke wurden zwei verschiedene Markierungsreagenzien mit dem kontrastgebenden Element Gadolinium synthetisiert. Gadolinium eignet sich aufgrund seines hohen magnetischen Moments hervorragend f{\"u}r die MRT-Bildgebung und da es in Biomolek{\"u}len nicht nat{\"u}rlich vorkommt, konnten die Reagenzien gleichermaßen f{\"u}r die Zellmarkierung und das Bioimaging mit der LA-ICP-MS untersucht werden. F{\"u}r die Synthese eines makromolekularen Reagenzes wurde das kommerziell verf{\"u}gbare Dendrimer G5-PAMAM {\"u}ber bifunktionelle Linker mit dem Chelator DOTA funktionalisiert, um anschließend Gadolinium zu komplexieren. Ein zweites, nanopartikul{\"a}res Reagenz wurde {\"u}ber eine Solvothermal-Synthese erhalten, bei der Ln:GdVO4-Nanokristalle mit einer funktionellen Polyacryls{\"a}ure(PAA)-H{\"u}lle dargestellt wurden. Die Dotierung der Ln:GdVO4-PAA Nanokristalle mit verschiedenen Lanthanoiden (Ln=Eu, Tb) zeigte ihre prinzipielle Multiplexf{\"a}higkeit in der LA-ICP-MS. Beide Markierungsreagenzien zeichneten sich durch gute Biovertr{\"a}glichkeiten und r1-Relaxivit{\"a}ten aus, was zudem ihr Potential f{\"u}r Anwendungen als pr{\"a}klinische „blood-pool" MRT-Kontrastmittel belegte. Die Untersuchung der Zellmarkierung erfolgte anhand einer Tumorzelllinie und einer Stammzelllinie, wobei beide Zellarten erfolgreich intrazellul{\"a}r mit beiden Reagenzien markiert wurden. Nach der Zellmarkierung veranschaulichte die in vitro MRT-Bildgebung von Zell-Phantomen eine deutlichere Kontrastverst{\"a}rkung der Zellen nach der Markierung mit den Nanokristallen im Vergleich zum kommerziellen Kontrastmittel Magnevist®. Die hohe Effizienz der Zellmarkierung mit den Nanokristallen und die damit verbundenen hohen Signalintensit{\"a}ten in einer einzelnen Zelle erlaubten beim Bioimaging mit der LA-ICP-MS, Messungen bis zu einer Aufl{\"o}sung von 4 µm Laser Spot Size. Nach der Zellmarkierung mit den DOTA(Gd3+)-funktionalisierten G5-PAMAM Dendrimeren waren hingegen Aufnahmen mit der LA-ICP-MS nur bis zu einer Aufl{\"o}sung von 12 µm Laser Spot Size m{\"o}glich. Insgesamt waren die Ln:GdVO4-PAA Nanokristalle mit gr{\"o}ßerer Ausbeute und kosteng{\"u}nstiger herstellbar als die DOTA(Gd3+)-funktionalisierten G5-PAMAM Dendrimere und zeigten zudem eine effizientere Zellmarkierung. Die Ln:GdVO4-PAA Nanokristalle erscheinen somit f{\"u}r das Zell-Tracking als besonders vielversprechend. Darauf aufbauend wurden die Nanokristalle zur Etablierung der Antik{\"o}rper-Konjugation ausgew{\"a}hlt, was sie f{\"u}r die molekulare in vivo Bildgebung sowie f{\"u}r die Immuno-Bildgebung von Gewebeschnitten oder Biopsie-Proben mit der LA-ICP-MS anwendbar macht.}, language = {de} } @phdthesis{Schulze2018, author = {Schulze, Sven}, title = {Entwicklung und Charakterisierung optischer Biosensorplattformen basierend auf photonischen Kristallen und Faser-Bragg-Gitter}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-422139}, school = {Universit{\"a}t Potsdam}, pages = {xviii, 149, A-23, B-2, C-8}, year = {2018}, abstract = {In dieser Arbeit steht die Entwicklung einer Sensorplattform f{\"u}r biochemische Anwendungen, welche auf einem optischen Detektionsprinzips beruht, im Vordergrund. W{\"a}hrend der Entwicklung wurden zwei komplement{\"a}re Konzeptideen behandelt, zum einen ein Sensor, der auf photonischen Kristallen und Wellenleiterstrukturen basiert und zum anderen einen faserbasierten Sensor, der chemisch modifizierte Faser-Bragg-Gitter enth{\"a}lt. Das optische Detektionsprinzip in beiden Sensorideen ist die resultierende Brechungsindex{\"a}nderung als messbare physikochemische Kenngr{\"o}ße. Das aus der Natur bekannte Ph{\"a}nomen der photonischen Kristalle, das u. a. bei Opalen und bei Schmetterlingen zu finden ist, wurde bereits 1887 von Lord Rayleigh beschrieben. Er beschrieb die optischen Eigenschaften von periodischen mehrschichtigen Filmen, welche als vereinfachtes Modell eines eindimensionalen photonischen Kristalls verstanden werden k{\"o}nnen. Die Periodizit{\"a}t der Brechungsindex{\"a}nderung resultiert in einem optischen Filter f{\"u}r Frequenzen in einem bestimmten spektralen Bereich, weshalb dann dort keine Lichtausbreitung mehr m{\"o}glich ist. Wird dieses System aber durch eine Defektstelle in der Brechungsindexperiodizit{\"a}t gest{\"o}rt, sodass daraus zwei perfekt periodische Systeme entstehen, ist die Lichtausbreitung f{\"u}r eine bestimmte Frequenz dennoch m{\"o}glich. In der Folge resultiert daraus ein schmalbandiges Signal im Transmissionsspektrum. Die erlaubte Frequenz ist dabei u. a. abh{\"a}ngig vom Brechungsindexunterschied des periodischen Systems, d.h. Ver{\"a}nderung des Brechungsindexes einer Schicht f{\"u}hrt zu einer spektralen Verschiebung der erlaubten Frequenz, dadurch kann dieses Sensorkonzept f{\"u}r biochemische Sensorik ausgenutzt werden [1]. Diese Entwicklung des auf photonischen Kristallen basierenden Sensors war eine Kooperation mit dem Industriepartner „Nanoplus GmbH". In der Doktorarbeit wurden Simulationen und praktischen Arbeiten zur Designentwicklung des Sensors und die Arbeiten an einem ersten Modellaufbau f{\"u}r die biochemischen Anwendungen durchgef{\"u}hrt. F{\"u}r den faserbasierten Sensor wurden Faser-Bragg-Gitter in den Faserkern hineingeschrieben. Hill et al. entdeckten 1978, dass solche Gitterstrukturen genau wie photonische Kristalle als optische Filter fungieren [2]. Die Gitter bestehen dabei aus {\"A}nderungen des Brechungsindexes im Faserkern. Im Laufe der n{\"a}chsten vierzig Jahren wurden verschiedene Einschreibetechniken und Gitterstrukturen entwickelt, weshalb die Eigenschaften der jeweiligen Gitterstrukturen variieren. Eine solche Gitterstruktur sind u. a. die Faser-Bragg-Gitter, deren Gitterperiode, d. h. die Abst{\"a}nde der Brechungsindexmodifikationen, sich im Nanometer- bis Mikrometerbereich befinden. Aufgrund der kleinen Gitterperiode wird eine r{\"u}ckw{\"a}rtsf{\"u}hrende Welle im Kern f{\"u}r eine bestimmte Frequenz bzw. Wellenl{\"a}nge, der Bragg-Wellenl{\"a}nge, erzeugt. Im Endeffekt resultiert daraus ein schmalbandiges Signal sowohl im Transmissionsspektrum, als auch im Reflexionsspektrum. Die Resonanzwellenl{\"a}nge ist dabei proportional zu der Gitterperiode und dem effektiven Brechungsindex, welcher vom Brechungsindex des Kerns und des kernumgebenen Materials abh{\"a}ngig ist. Letztlich eignet sich diese Technik f{\"u}r physikochemische Sensorik. Im Rahmen dieser Arbeit wurden die Gitter mit Hilfe einer relativen neuen Herstellungsmethode in die Fasern geschrieben [3]. Anschließend stand die Entwicklung eines Biosensors im Vordergrund, wobei zun{\"a}chst ein Protokoll zum {\"A}tzen der Faser mit Flusss{\"a}ure entwickelt worden ist, dass das System sensitiv zum umgebenen Brechungsindex macht. Am Ende wurde ein Modellaufbau realisiert, indem ein Modellsystem, hier die Detektion vom C-reaktiven Protein mittels spezifischen einzelstr{\"a}ngigen DNS-Aptameren, erfolgreich getestet und quantifiziert worden ist. 1 Mandal, S.; Erickson, D. Nanoscale Optofluidic Sensor Arrays. Opt. Express 2008, 16 (3), 1623-1631. 2 Hill, K. O.; Fujii, Y.; Johnson, D. C.; Kawasaki, B. S. Photosensitivity in Optical Fiber Waveguides: Application to Reflection Filter Fabrication. Appl. Phys. Lett. 1978, 32 (10), 647-649. 3 Mart{\´i}nez, A.; Dubov, M.; Khrushchev, I.; Bennion, I. Direct Writing of Fibre Bragg Gratings by Femtosecond Laser. Electron. Lett. 2004, 40 (19), 1170.}, language = {de} } @phdthesis{Jaeger2018, author = {Jaeger, David}, title = {Enabling Big Data security analytics for advanced network attack detection}, doi = {10.25932/publishup-43571}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-435713}, school = {Universit{\"a}t Potsdam}, pages = {XVII, 201, XXXIII}, year = {2018}, abstract = {The last years have shown an increasing sophistication of attacks against enterprises. Traditional security solutions like firewalls, anti-virus systems and generally Intrusion Detection Systems (IDSs) are no longer sufficient to protect an enterprise against these advanced attacks. One popular approach to tackle this issue is to collect and analyze events generated across the IT landscape of an enterprise. This task is achieved by the utilization of Security Information and Event Management (SIEM) systems. However, the majority of the currently existing SIEM solutions is not capable of handling the massive volume of data and the diversity of event representations. Even if these solutions can collect the data at a central place, they are neither able to extract all relevant information from the events nor correlate events across various sources. Hence, only rather simple attacks are detected, whereas complex attacks, consisting of multiple stages, remain undetected. Undoubtedly, security operators of large enterprises are faced with a typical Big Data problem. In this thesis, we propose and implement a prototypical SIEM system named Real-Time Event Analysis and Monitoring System (REAMS) that addresses the Big Data challenges of event data with common paradigms, such as data normalization, multi-threading, in-memory storage, and distributed processing. In particular, a mostly stream-based event processing workflow is proposed that collects, normalizes, persists and analyzes events in near real-time. In this regard, we have made various contributions in the SIEM context. First, we propose a high-performance normalization algorithm that is highly parallelized across threads and distributed across nodes. Second, we are persisting into an in-memory database for fast querying and correlation in the context of attack detection. Third, we propose various analysis layers, such as anomaly- and signature-based detection, that run on top of the normalized and correlated events. As a result, we demonstrate our capabilities to detect previously known as well as unknown attack patterns. Lastly, we have investigated the integration of cyber threat intelligence (CTI) into the analytical process, for instance, for correlating monitored user accounts with previously collected public identity leaks to identify possible compromised user accounts. In summary, we show that a SIEM system can indeed monitor a large enterprise environment with a massive load of incoming events. As a result, complex attacks spanning across the whole network can be uncovered and mitigated, which is an advancement in comparison to existing SIEM systems on the market.}, language = {en} } @phdthesis{SanchezGarcia2018, author = {S{\´a}nchez Garc{\´i}a, Mar{\´i}a Clemencia}, title = {El parlache como elemento evocador de la oralidad ficcional en la novela Rosario Tijeras, de Jorge Franco}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-415297}, school = {Universit{\"a}t Potsdam}, pages = {xxi, 283}, year = {2018}, abstract = {El objetivo de este trabajo es investigar c{\´o}mo se evoca la realidad del habla en la novela Rosario Tijeras, del colombiano Jorge Franco, y sus traducciones al alem{\´a}n y al ingl{\´e}s. En esta novela negra, el autor recurre a un lenguaje coloquial llamado parlache, t{\´i}pico de un sector socioecon{\´o}mico marginal de Medell{\´i}n, y cuya influencia se ha extendido a todos los {\´a}mbitos de la ciudad y del pa{\´i}s. El estudio se centrar{\´a} en la descripci{\´o}n de la variaci{\´o}n diat{\´o}pica y diastr{\´a}tica en la ficci{\´o}n; concretamente, de las expresiones t{\´i}picas del parlache. Con ello se pretende determinar la contribuci{\´o}n de ciertos recursos ling{\"u}{\´i}sticos t{\´i}picos de esta variedad del espa{\~n}ol a la construcci{\´o}n de un di{\´a}logo hablado veros{\´i}mil. Adem{\´a}s, se estudiar{\´a} c{\´o}mo se reexpresa este «colorido local» en la evocaci{\´o}n de la oralidad en las traducciones. Se intentar{\´a}n determinar, por tanto, las divergencias de traducci{\´o}n y profundizar en la descripci{\´o}n de la variaci{\´o}n ling{\"u}{\´i}stica (diat{\´o}pica y diastr{\´a}tica) en la traducci{\´o}n literaria.}, language = {es} } @phdthesis{Fabian2018, author = {Fabian, Jenny}, title = {Effects of algae on microbial carbon cycling in freshwaters}, doi = {10.25932/publishup-42222}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-422225}, school = {Universit{\"a}t Potsdam}, pages = {90}, year = {2018}, abstract = {Microbial processing of organic matter (OM) in the freshwater biosphere is a key component of global biogeochemical cycles. Freshwaters receive and process valuable amounts of leaf OM from their terrestrial landscape. These terrestrial subsidies provide an essential source of energy and nutrients to the aquatic environment as a function of heterotrophic processing by fungi and bacteria. Particularly in freshwaters with low in-situ primary production from algae (microalgae, cyanobacteria), microbial turnover of leaf OM significantly contributes to the productivity and functioning of freshwater ecosystems and not least their contribution to global carbon cycling. Based on differences in their chemical composition, it is believed that leaf OM is less bioavailable to microbial heterotrophs than OM photosynthetically produced by algae. Especially particulate leaf OM, consisting predominantly of structurally complex and aromatic polymers, is assumed highly resistant to enzymatic breakdown by microbial heterotrophs. However, recent research has demonstrated that OM produced by algae promotes the heterotrophic breakdown of leaf OM in aquatic ecosystems, with profound consequences for the metabolism of leaf carbon (C) within microbial food webs. In my thesis, I aimed at investigating the underlying mechanisms of this so called priming effect of algal OM on the use of leaf C in natural microbial communities, focusing on fungi and bacteria. The works of my thesis underline that algal OM provides highly bioavailable compounds to the microbial community that are quickly assimilated by bacteria (Paper II). The substrate composition of OM pools determines the proportion of fungi and bacteria within the microbial community (Paper I). Thereby, the fraction of algae OM in the aquatic OM pool stimulates the activity and hence contribution of bacterial communities to leaf C turnover by providing an essential energy and nutrient source for the assimilation of the structural complex leaf OM substrate. On the contrary, the assimilation of algal OM remains limited for fungal communities as a function of nutrient competition between fungi and bacteria (Paper I, II). In addition, results provide evidence that environmental conditions determine the strength of interactions between microalgae and heterotrophic bacteria during leaf OM decomposition (Paper I, III). However, the stimulatory effect of algal photoautotrophic activities on leaf C turnover remained significant even under highly dynamic environmental conditions, highlighting their functional role for ecosystem processes (Paper III). The results of my thesis provide insights into the mechanisms by which algae affect the microbial turnover of leaf C in freshwaters. This in turn contributes to a better understanding of the function of algae in freshwater biogeochemical cycles, especially with regard to their interaction with the heterotrophic community.}, language = {en} } @phdthesis{SaadHassanin2018, author = {Saad Hassanin, Alshaimaa}, title = {Dynamic coronal mass ejection process and magnetic reconnection}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-419626}, school = {Universit{\"a}t Potsdam}, pages = {xix, 113}, year = {2018}, abstract = {The Sun is the nearest star to the Earth. It consists of an interior and an atmosphere. The convection zone is the outermost layer of the solar interior. A flux rope may emerge as a coherent structure from the convection zone into the solar atmosphere or be formed by magnetic reconnection in the atmosphere. A flux rope is a bundle of magnetic field lines twisting around an axis field line, creating a helical shape by which dense filament material can be supported against gravity. The flux rope is also considered as the key structure of the most energetic phenomena in the solar system, such as coronal mass ejections (CMEs) and flares. These magnetic flux ropes can produce severe geomagnetic storms. In particular, to improve the ability to forecast space weather, it is important to enrich our knowledge about the dynamic formation of flux ropes and the underlying physical mechanisms that initiate their eruption, such as a CME. A confined eruption consists of a filament eruption and usually an associated are, but does not evolve into a CME; rather, the moving plasma is halted in the solar corona and usually seen to fall back. The first detailed observations of a confined filament eruption were obtained on 2002 May 27by the TRACE satellite in the 195 A band. So, in the Chapter 3, we focus on a flux rope instability model. A twisted flux rope can become unstable by entering the kink instability regime. We show that the kink instability, which occurs if the twist of a flux rope exceeds a critical value, is capable of initiating of an eruption. This model is tested against the well observed confined eruption on 2002 May 27 in a parametric magnetohydrodynamic (MHD) simulation study that comprises all phases of the event. Very good agreement with the essential observed properties is obtained, only except for a relatively poor matching of the initial filament height. Therefore, in Chapter 4, we submerge the center point of the flux rope deeper below the photosphere to obtain a flatter coronal rope section and a better matching with the initial height profile of the erupting filament. This implies a more realistic inclusion of the photospheric line tying. All basic assumptions and the other parameter settings are kept the same as in Chapter 3. This complement of the parametric study shows that the flux rope instability model can yield an even better match with the observational data. We also focus in Chapters 3 and 4 on the magnetic reconnection during the confined eruption, demonstrating that it occurs in two distinct locations and phases that correspond to the observed brightenings and changes of topology, and consider the fate of the erupting flux, which can reform a (less twisted) flux rope. The Sun also produces series of homologous eruptions, i.e. eruptions which occur repetitively in the same active region and are of similar morphology. Therefore, in Chapter 5, we employ the reformed flux rope as a new initial condition, to investigate the possibility of subsequent homologous eruptions. Free magnetic energy is built up by imposing motions in the bottom boundary, such as converging motions, leading to flux cancellation. We apply converging motions in the sunspot area, such that a small part of the flux from the sunspots with different polarities is transported toward the polarity inversion line (PIL) and cancels with each other. The reconnection associated with the cancellation process forms more helical magnetic flux around the reformed flux rope, which leads to a second and a third eruption. In this study, we obtain the first MHD simulation results of a homologous sequence of eruptions that show a transition from a confined to two ejective eruptions, based on the reformation of a flux rope after each eruption.}, language = {en} } @phdthesis{Choi2018, author = {Choi, Youngeun}, title = {DNA origami structures as versatile platforms for nanophotonics}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-421483}, school = {Universit{\"a}t Potsdam}, pages = {125}, year = {2018}, abstract = {Nanophotonics is the field of science and engineering aimed at studying the light-matter interactions on the nanoscale. One of the key aspects in studying such optics at the nanoscale is the ability to assemble the material components in a spatially controlled manner. In this work, DNA origami nanostructures were used to self-assemble dye molecules and DNA coated plasmonic nanoparticles. Optical properties of dye nanoarrays, where the dyes were arranged at distances where they can interact by F{\"o}rster resonance energy transfer (FRET), were systematically studied according to the size and arrangement of the dyes using fluorescein (FAM) as the donor and cyanine 3 (Cy 3) as the acceptor. The optimized design, based on steady-state and time-resolved fluorometry, was utilized in developing a ratiometric pH sensor with pH-inert coumarin 343 (C343) as the donor and pH-sensitive FAM as the acceptor. This design was further applied in developing a ratiometric toxin sensor, where the donor C343 is unresponsive and FAM is responsive to thioacetamide (TAA) which is a well-known hepatotoxin. The results indicate that the sensitivity of the ratiometric sensor can be improved by simply arranging the dyes into a well-defined array. The ability to assemble multiple fluorophores without dye-dye aggregation also provides a strategy to amplify the signal measured from a fluorescent reporter, and was utilized here to develop a reporter for sensing oligonucleotides. By incorporating target capturing sequences and multiple fluorophores (ATTO 647N dye molecules), a reporter for microbead-based assay for non-amplified target oligonucleotide sensing was developed. Analysis of the assay using VideoScan, a fluorescence microscope-based technology capable of conducting multiplex analysis, showed the DNA origami nanostructure based reporter to have a lower limit of detection than a single stranded DNA reporter. Lastly, plasmonic nanostructures were assembled on DNA origami nanostructures as substrates to study interesting optical behaviors of molecules in the near-field. Specifically, DNA coated gold nanoparticles, silver nanoparticles, and gold nanorods, were placed on the DNA origami nanostructure aiming to study surface-enhanced fluorescence (SEF) and surface-enhanced Raman scattering (SERS) of molecules placed in the hotspot of coupled plasmonic structures.}, language = {en} } @phdthesis{Bazhenova2018, author = {Bazhenova, Ekaterina}, title = {Discovery of Decision Models Complementary to Process Models}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-410020}, school = {Universit{\"a}t Potsdam}, year = {2018}, abstract = {Business process management is an acknowledged asset for running an organization in a productive and sustainable way. One of the most important aspects of business process management, occurring on a daily basis at all levels, is decision making. In recent years, a number of decision management frameworks have appeared in addition to existing business process management systems. More recently, Decision Model and Notation (DMN) was developed by the OMG consortium with the aim of complementing the widely used Business Process Model and Notation (BPMN). One of the reasons for the emergence of DMN is the increasing interest in the evolving paradigm known as the separation of concerns. This paradigm states that modeling decisions complementary to processes reduces process complexity by externalizing decision logic from process models and importing it into a dedicated decision model. Such an approach increases the agility of model design and execution. This provides organizations with the flexibility to adapt to the ever increasing rapid and dynamic changes in the business ecosystem. The research gap, identified by us, is that the separation of concerns, recommended by DMN, prescribes the externalization of the decision logic of process models in one or more separate decision models, but it does not specify this can be achieved. The goal of this thesis is to overcome the presented gap by developing a framework for discovering decision models in a semi-automated way from information about existing process decision making. Thus, in this thesis we develop methodologies to extract decision models from: (1) control flow and data of process models that exist in enterprises; and (2) from event logs recorded by enterprise information systems, encapsulating day-to-day operations. Furthermore, we provide an extension of the methodologies to discover decision models from event logs enriched with fuzziness, a tool dealing with partial knowledge of the process execution information. All the proposed techniques are implemented and evaluated in case studies using real-life and synthetic process models and event logs. The evaluation of these case studies shows that the proposed methodologies provide valid and accurate output decision models that can serve as blueprints for executing decisions complementary to process models. Thus, these methodologies have applicability in the real world and they can be used, for example, for compliance checks, among other uses, which could improve the organization's decision making and hence it's overall performance.}, language = {en} } @phdthesis{Antić2018, author = {Antić, Andreas}, title = {Digitale {\"O}ffentlichkeiten und intelligente Kooperation}, publisher = {Universit{\"a}tsverlag Potsdam}, address = {Potsdam}, isbn = {978-3-86956-431-9}, doi = {10.25932/publishup-41096}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-410964}, school = {Universit{\"a}t Potsdam}, pages = {ii, 454}, year = {2018}, abstract = {Um die gegenw{\"a}rtige Transformation der {\"O}ffentlichkeit im digitalen Zeitalter erfassen zu k{\"o}nnen, ist in der {\"O}ffentlichkeitstheorie eine erweiterte Perspektive notwendig, die nicht nur den massenmedialen Diskurs, sondern auch die Ver{\"a}nderung sozialer Praktiken und institutioneller Strukturen in den Blick nimmt. Das Ziel dieses Buches besteht darin, die Grundlagen einer solchen Perspektive auf die Theorie digitaler {\"O}ffentlichkeiten zu entwickeln. Im vorgeschlagenen Ansatz wird {\"O}ffentlichkeit im Anschluss an John Dewey als Prozess verstanden. In seiner prozessualen und funktionalen Bestimmung von {\"O}ffentlichkeit liegt eine besondere Originalit{\"a}t, die seinen Ansatz von anderen {\"O}ffentlichkeitskonzeptionen unterscheidet. Das Buch liefert sowohl eine systematische Rekonstruktion und Interpretation der Philosophie John Deweys als auch einen Vorschlag zur gesellschaftstheoretischen Deutung des digitalen Wandels.}, language = {de} } @phdthesis{vonNordheim2018, author = {von Nordheim, Danny}, title = {Dielectric non-linearities of P(VDF-TrFE) single and multilayers for memory applications}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-421778}, school = {Universit{\"a}t Potsdam}, pages = {XVI, 109}, year = {2018}, abstract = {Poly(vinylidene fluoride-trifluoroethylene) (P(VDF-TrFE)) ferroelectric thin films of different molar ratio have been studied with regard to data memory applications. Therefore, films with thicknesses of 200 nm and less have been spin coated from solution. Observations gained from single layers have been extended to multilayer capacitors and three terminal transistor devices. Besides conventional hysteresis measurements, the measurement of dielectric non-linearities has been used as a main tool of characterisation. Being a very sensitive and non-destructive method, non-linearity measurements are well suited for polarisation readout and property studies. Samples have been excited using a high quality, single-frequency sinusoidal voltage with an amplitude significantly smaller than the coercive field of the samples. The response was then measured at the excitation frequency and its higher harmonics. Using the measurement results, the linear and non-linear dielectric permittivities ɛ₁, ɛ₂ and ɛ₃ have been determined. The permittivities have been used to derive the temperature-dependent polarisation behaviour as well as the polarisation state and the order of the phase transitions. The coercive field in VDF-TrFE copolymers is high if compared to their ceramic competitors. Therefore, the film thickness had to be reduced significantly. Considering a switching voltage of 5 V and a coercive field of 50 MV/m, the film thickness has to be 100 nm and below. If the thickness becomes substantially smaller than the other dimensions, surface and interface layer effects become more pronounced. For thicker films of P(VDF-TrFE) with a molar fraction of 56/44 a second-order phase transition without a thermal hysteresis for an ɛ₁(T) temperature cycle has been predicted and observed. This however, could not be confirmed by the measurements of thinner films. A shift of transition temperatures as well as a temperature independent, non-switchable polarisation and a thermal hysteresis for P(VDF-TrFE) 56/44 have been observed. The impact of static electric fields on the polarisation and the phase transition has therefore been studied and simulated, showing that all aforementioned phenomena including a linear temperature dependence of the polarisation might originate from intrinsic electric fields. In further experiments the knowledge gained from single layer capacitors has been extended to bilayer copolymer thin films of different molar composition. Bilayers have been deposited by succeeding cycles of spin coating from solution. Single layers and their bilayer combination have been studied individually in order to prove the layers stability. The individual layers have been found to be physically stable. But while the bilayers reproduced the main ɛ₁(T) properties of the single layers qualitatively, quantitative numbers could not be explained by a simple serial connection of capacitors. Furthermore, a linear behaviour of the polarisation throughout the measured temperature range has been observed. This was found to match the behaviour predicted considering a constant electric field. Retention time is an important quantity for memory applications. Hence, the retention behaviour of VDF-TrFE copolymer thin films has been determined using dielectric non-linearities. The polarisation loss in P(VDF-TrFE) poled samples has been found to be less than 20\% if recorded over several days. The loss increases significantly if the samples have been poled with lower amplitudes, causing an unsaturated polarisation. The main loss was attributed to injected charges. Additionally, measurements of dielectric non-linearities have been proven to be a sensitive and non-destructive tool to measure the retention behaviour. Finally, a ferroelectric field effect transistor using mainly organic materials (FerrOFET) has been successfully studied. DiNaphtho[2,3-b:2',3'-f]Thieno[3,2-b]Thiophene (DNTT) has proven to be a stable, suitable organic semiconductor to build up ferroelectric memory devices. Furthermore, an oxidised aluminium bottom electrode and additional dielectric layers, i.e. parylene C, have proven to reduce the leakage current and therefore enhance the performance significantly.}, language = {en} } @phdthesis{SchulteUmberg2018, author = {Schulte-Umberg, Ulf}, title = {Die langobardischen Hofkirchen in Capua}, doi = {10.25932/publishup-48109}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-481099}, school = {Universit{\"a}t Potsdam}, pages = {VII, 427}, year = {2018}, abstract = {Im historischen Zentrum der mittelalterlichen Stadt Capua hat sich mit den drei Kirchen S. Salvatore „Maggiore" a Corte, S. Giovanni a Corte und S. Michele a Corte eine Gruppe von Sakralbauten erhalten, die nicht nur durch ihre {\"u}bereinstimmende namentliche Attribution einen Zusammenhang mit dem langobardischen F{\"u}rstenhof der Stadt offenbaren, sondern auch durch die r{\"a}umliche Disposition im urbanistischen Gef{\"u}ge. Im vorliegenden Buch wird die {\"u}berkommene Bausubstanz einer grundlegenden Analyse unterzogen, um herauszuarbeiten, welche Bestandteile den {\"a}ltesten Bauphasen zuzuordnen sind und somit als langobardenzeitlich angesprochen werden k{\"o}nnen. Eine ausf{\"u}hrliche Untersuchung der zugeh{\"o}rigen Bauplastik erg{\"a}nzt gleichwertig diesen ersten Teil. Die Kontextualisierung der Ergebnisse hilft dabei, ein Bild von der Kunst und Architektur des in S{\"u}ditalien an Monumenten eher armen 10. Jahrhunderts zu generieren und erlaubt R{\"u}ckschl{\"u}sse auf den geistigen Hintergrund, vor dem die drei Hofkirchen entstanden sind.}, language = {de} } @phdthesis{Kirchner2018, author = {Kirchner, Moritz}, title = {Der neueste Geist des Kapitalismus}, doi = {10.25932/publishup-41498}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-414985}, school = {Universit{\"a}t Potsdam}, pages = {520}, year = {2018}, abstract = {Der neueste Geist des Kapitalismus beschreibt das heutige Mobilisierungs- und Rechtfertigungsregime, welches uns immer wieder dazu bringt, unsere Arbeitskraft zu verwerten und uns t{\"a}glich ins kapitalistische Hamsterrad zu begeben. Der alte Geist des Kapitalismus, nach dem Fleiß, Disziplin und Sparsamkeit zum gesellschaftlichen Aufstieg f{\"u}hren, tr{\"a}gt l{\"a}ngst nicht mehr. Auch reine Selbstverwirklichung, der Anspruch auf Flexibilit{\"a}t und flache Hierarchien reicht nicht mehr aus, um insbesondere gut qualifizierte Menschen zur Arbeit zu motivieren. Der neueste Geist des Kapitalismus hingegen ist das Produkt der tiefen Subjektivierung und Verinnerlichung des Neoliberalismus. Es geht um best{\"a}ndige berufliche und private Optimierung sowie ein umfassendes Nutzendenken. Gl{\"u}cklich zu sein, ist nicht mehr nur eine Option, sondern es gibt den normativen Anspruch, gl{\"u}cklich sein zu sollen. Das Leistungsprinzip wird aktiv bejaht und Leistungsgerechtigkeit eingefordert. Die Bew{\"a}ltigung von Komplexit{\"a}t wird zum Metathema. Der Anspruch auf Distinktion, insbesondere auch gegen{\"u}ber „Minderleisten" nimmt zu. Die Welt wird zunehmend durch die Brille von Zahlen und Statistiken betrachtet, und Key Performance Indicators werden zu st{\"a}ndigen Wegbegleitern. Das Leben wird, verst{\"a}rkt durch die sozialen Netzwerke, zunehmend zu einer performativen B{\"u}hne, die zugleich dem Networking dient. In der Konsequenz der best{\"a}ndigen Optimierung wird es jedoch immer schwerer, zur Ruhe zu kommen. Dieser neueste Geist des Kapitalismus, dieser umfassende Optimierungsanspruch, hat jedoch gravierende Konsequenzen. Zu den manifesten Pathologien des neuesten Geistes geh{\"o}ren gestiegene Raten von Depressionen, Burn-out und Angstst{\"o}rungen. Gesellschaftlich spreizt sich die soziale Schere immer mehr anhand der F{\"a}higkeit, Komplexit{\"a}t bew{\"a}ltigen zu k{\"o}nnen, was viele Verlierer und prek{\"a}re Gewinner produziert. Daher wird dieser neueste Geist des Kapitalismus sozialkritisch, k{\"u}nstlerkritisch und ideologiekritisch hinterfragt. Die Rolle der Gewerkschaften als der Zentralinstitution der Sozialkritik, die ein tats{\"a}chliches Gegengewicht zum neuesten Geist des Kapitalismus bieten kann, wird kontrovers diskutiert. Und es wird aufgezeigt: chillen ist die neue Subversion.}, language = {de} } @phdthesis{Fliesser2018, author = {Fließer, Michael}, title = {Der Einfluss unterschiedlicher Indikatoren des sozio{\"o}konomischen Status auf R{\"u}ckenschmerz}, doi = {10.25932/publishup-42345}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-423455}, school = {Universit{\"a}t Potsdam}, pages = {84}, year = {2018}, abstract = {Obwohl der sozio{\"o}konomische Status (SES) eine in der Sozialepidemiologie h{\"a}ufig gebrauchte Variable darstellt, ist seine Verwendung mit methodischen Problemen verkn{\"u}pft: Seine latente Struktur f{\"u}hrt dazu, dass sich verschiedene M{\"o}glichkeiten der Operationalisierung er{\"o}ffnen. Diese reichen von klassischen Ungleichheitsindikatoren wie Bildung, Einkommen oder Berufsposition, {\"u}ber multidimensionale oder {\"u}ber Nachbarschaftsmerkmale konstruierte Indizes, bis hin zu subjektiven Statuseinsch{\"a}tzungen. Problematisch ist dies insofern, als verschiedene Indikatoren auf unterschiedlichen theoretischen Konstrukten beruhen und unterschiedliche Schlussfolgerungen erlauben. In dieser Arbeit wird deshalb in einem ersten Schritt anhand eines systematischen Reviews zum Zusammenhang von SES und R{\"u}ckenschmerzen {\"u}berpr{\"u}ft, welche Indikatoren in wissenschaftlichen Publikationen eingesetzt werden und wie die Auswahl begr{\"u}ndet wird. Das Ergebnis zeigt eine klare Pr{\"a}ferenz f{\"u}r klassische Indikatoren (Bildung, Einkommen und Berufsposition). Erl{\"a}utert wurde die jeweilige Auswahl allerdings nur in einem geringen Prozentsatz der untersuchten Artikel, obwohl die unterschiedlichen Studienergebnisse nahelegen, dass der gew{\"a}hlte Indikator einen Einfluss auf den gefundenen Zusammenhang aus{\"u}ben k{\"o}nnte. Deshalb wurde in einem weiteren Schritt {\"u}berpr{\"u}ft, wie unterschiedliche SES-Indikatoren mit der Verbesserung von R{\"u}ckenschmerzen nach einer Rehabilitation (Studie 1) und der Neuentstehung von R{\"u}ckenschmerzen (Studie 2) zusammenh{\"a}ngen. Außerdem wurde untersucht, ob ein einfaches Modell den Zusammenhang von SES und Gesundheit so darstellen kann, dass a priori abzusch{\"a}tzen ist, wie hoch der Einfluss unterschiedlicher Indikatoren auf einen bestimmten Gesundheitsoutput sein k{\"o}nnte. Es zeigt sich, dass sich der errechnete Zusammenhang zwischen den verschiedenen Indikatoren und chronischen R{\"u}ckenschmerzen erheblich unterscheidet: F{\"u}r Menschen, die bereits wegen R{\"u}ckenschmerzen in Rehabilitation waren, erwiesen sich Bildung und Berufsposition als {\"a}hnlich einflussreiche Einflussfaktoren, w{\"a}hrend f{\"u}r das Einkommen kein bedeutender Zusammenhang festgestellt werden konnte. F{\"u}r die Neuentstehung chronischer R{\"u}ckenschmerzen zeigte sich die Berufsposition als wichtigster Indikator, gefolgt von Bildung, w{\"a}hrend f{\"u}r Einkommen kein signifikanter Zusammenhang gefunden werden konnte. Folglich bestimmt die Wahl des Indikators die H{\"o}he des festgestellten Zusammenhangs stark mit. Unterschiedliche Indikatoren d{\"u}rfen deshalb nicht als austauschbar betrachtet werden und es muss bei jeder Forschungsfrage genau {\"u}berlegt werden, welcher Indikator f{\"u}r die jeweilige Fragestellung am besten verwendet werden kann. Das vorgeschlagene theoretische Modell kann dabei als Unterst{\"u}tzung dienen.}, language = {de} } @phdthesis{Holl2018, author = {Holl, Anna Katharina}, title = {Deficits in theory of mind and executive function as risk factors for conduct problems from middle childhood to early adolescence - a longitudinal perspective}, doi = {10.25932/publishup-45991}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-459915}, school = {Universit{\"a}t Potsdam}, pages = {292}, year = {2018}, abstract = {In this thesis, deficits in theory of mind (ToM) and executive function (EF) were examined in tandem and separately as risk factors for conduct problems, including different forms and functions of aggressive behavior. All three reported studies and the additional analyses were based on a large community sample of N = 1,657 children, including three waves of a longitudinal study covering middle childhood and the transition to early adolescence (range 6 to 13 years) over a total of about three years. All data were analyzed with structural equation modeling. Altogether, the results of all the conducted studies in this thesis extend previous research and confirm the propositions of the SIP model (Crick \& Dodge, 1994) and of the amygdala theory of violent behavior (e.g., Blair et al., 2014) besides other accounts. Considering the three main research questions, the results of the thesis suggest first that deficits in ToM are a risk factor for relational and physical aggression from a mean age of 8 to 11 years under the control of stable between-person differences in aggression. In addition, earlier relationally aggressive behavior predicts later deficits in ToM in this age range, which confirms transactional relations between deficits in ToM and aggressive behavior in children (Crick \& Dodge, 1994). Further, deficits in ToM seem to be a risk factor for parent-rated conduct problems cross-sectionally in an age range from 9 to 13 years. Second, deficits in cool EF are a risk factor for later physical, relational, and reactive aggression but not for proactive aggression over a course of three years from middle childhood to early adolescence. Habitual anger seems to mediate the relation between cool EF and physical, and as a trend also relational, aggression. Deficits in emotional and inhibitory control and planning have a direct effect on the individual level of conduct problems under the control of interindividual differences in conduct problems at a mean age of 8 years, but not on the trajectory of conduct problems over the course from age 8 to 11. Third, when deficits in cool EF and ToM are studied in tandem cross-sectionally at the transition from middle childhood to early adolescence, deficits in cool EF seem to play only an indirect role through deficits in ToM as a risk factor for conduct problems. Finally, all results hold equal for females and males in the conducted studies. The results of this thesis emphasize the need to intervene in the transactional processes between deficits in ToM and in EF and conduct problems, including different forms and functions of aggression, particularly in the socially sensible period from middle and late childhood to early adolescence.}, language = {en} } @phdthesis{Smith2018, author = {Smith, Taylor}, title = {Decadal changes in the snow regime of High Mountain Asia, 1987-2016}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-407120}, school = {Universit{\"a}t Potsdam}, pages = {xiii, 142}, year = {2018}, abstract = {More than a billion people rely on water from rivers sourced in High Mountain Asia (HMA), a significant portion of which is derived from snow and glacier melt. Rural communities are heavily dependent on the consistency of runoff, and are highly vulnerable to shifts in their local environment brought on by climate change. Despite this dependence, the impacts of climate change in HMA remain poorly constrained due to poor process understanding, complex terrain, and insufficiently dense in-situ measurements. HMA's glaciers contain more frozen water than any region outside of the poles. Their extensive retreat is a highly visible and much studied marker of regional and global climate change. However, in many catchments, snow and snowmelt represent a much larger fraction of the yearly water budget than glacial meltwaters. Despite their importance, climate-related changes in HMA's snow resources have not been well studied. Changes in the volume and distribution of snowpack have complex and extensive impacts on both local and global climates. Eurasian snow cover has been shown to impact the strength and direction of the Indian Summer Monsoon -- which is responsible for much of the precipitation over the Indian Subcontinent -- by modulating earth-surface heating. Shifts in the timing of snowmelt have been shown to limit the productivity of major rangelands, reduce streamflow, modify sediment transport, and impact the spread of vector-borne diseases. However, a large-scale regional study of climate impacts on snow resources had yet to be undertaken. Passive Microwave (PM) remote sensing is a well-established empirical method of studying snow resources over large areas. Since 1987, there have been consistent daily global PM measurements which can be used to derive an estimate of snow depth, and hence snow-water equivalent (SWE) -- the amount of water stored in snowpack. The SWE estimation algorithms were originally developed for flat and even terrain -- such as the Russian and Canadian Arctic -- and have rarely been used in complex terrain such as HMA. This dissertation first examines factors present in HMA that could impact the reliability of SWE estimates. Forest cover, absolute snow depth, long-term average wind speeds, and hillslope angle were found to be the strongest controls on SWE measurement reliability. While forest density and snow depth are factors accounted for in modern SWE retrieval algorithms, wind speed and hillslope angle are not. Despite uncertainty in absolute SWE measurements and differences in the magnitude of SWE retrievals between sensors, single-instrument SWE time series were found to be internally consistent and suitable for trend analysis. Building on this finding, this dissertation tracks changes in SWE across HMA using a statistical decomposition technique. An aggregate decrease in SWE was found (10.6 mm/yr), despite large spatial and seasonal heterogeneities. Winter SWE increased in almost half of HMA, despite general negative trends throughout the rest of the year. The elevation distribution of these negative trends indicates that while changes in SWE have likely impacted glaciers in the region, climate change impacts on these two pieces of the cryosphere are somewhat distinct. Following the discussion of relative changes in SWE, this dissertation explores changes in the timing of the snowmelt season in HMA using a newly developed algorithm. The algorithm is shown to accurately track the onset and end of the snowmelt season (70\% within 5 days of a control dataset, 89\% within 10). Using a 29-year time series, changes in the onset, end, and duration of snowmelt are examined. While nearly the entirety of HMA has experienced an earlier end to the snowmelt season, large regions of HMA have seen a later start to the snowmelt season. Snowmelt periods have also decreased in almost all of HMA, indicating that the snowmelt season is generally shortening and ending earlier across HMA. By examining shifts in both the spatio-temporal distribution of SWE and the timing of the snowmelt season across HMA, we provide a detailed accounting of changes in HMA's snow resources. The overall trend in HMA is towards less SWE storage and a shorter snowmelt season. However, long-term and regional trends conceal distinct seasonal, temporal, and spatial heterogeneity, indicating that changes in snow resources are strongly controlled by local climate and topography, and that inter-annual variability plays a significant role in HMA's snow regime.}, language = {en} } @phdthesis{Schwahn2018, author = {Schwahn, Kevin}, title = {Data driven approaches to infer the regulatory mechanism shaping and constraining levels of metabolites in metabolic networks}, doi = {10.25932/publishup-42324}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-423240}, school = {Universit{\"a}t Potsdam}, pages = {109}, year = {2018}, abstract = {Systems biology aims at investigating biological systems in its entirety by gathering and analyzing large-scale data sets about the underlying components. Computational systems biology approaches use these large-scale data sets to create models at different scales and cellular levels. In addition, it is concerned with generating and testing hypotheses about biological processes. However, such approaches are inevitably leading to computational challenges due to the high dimensionality of the data and the differences in the dimension of data from different cellular layers. This thesis focuses on the investigation and development of computational approaches to analyze metabolite profiles in the context of cellular networks. This leads to determining what aspects of the network functionality are reflected in the metabolite levels. With these methods at hand, this thesis aims to answer three questions: (1) how observability of biological systems is manifested in metabolite profiles and if it can be used for phenotypical comparisons; (2) how to identify couplings of reaction rates from metabolic profiles alone; and (3) which regulatory mechanism that affect metabolite levels can be distinguished by integrating transcriptomics and metabolomics read-outs. I showed that sensor metabolites, identified by an approach from observability theory, are more correlated to each other than non-sensors. The greater correlations between sensor metabolites were detected both with publicly available metabolite profiles and synthetic data simulated from a medium-scale kinetic model. I demonstrated through robustness analysis that correlation was due to the position of the sensor metabolites in the network and persisted irrespectively of the experimental conditions. Sensor metabolites are therefore potential candidates for phenotypical comparisons between conditions through targeted metabolic analysis. Furthermore, I demonstrated that the coupling of metabolic reaction rates can be investigated from a purely data-driven perspective, assuming that metabolic reactions can be described by mass action kinetics. Employing metabolite profiles from domesticated and wild wheat and tomato species, I showed that the process of domestication is associated with a loss of regulatory control on the level of reaction rate coupling. I also found that the same metabolic pathways in Arabidopsis thaliana and Escherichia coli exhibit differences in the number of reaction rate couplings. I designed a novel method for the identification and categorization of transcriptional effects on metabolism by combining data on gene expression and metabolite levels. The approach determines the partial correlation of metabolites with control by the principal components of the transcript levels. The principle components contain the majority of the transcriptomic information allowing to partial out the effect of the transcriptional layer from the metabolite profiles. Depending whether the correlation between metabolites persists upon controlling for the effect of the transcriptional layer, the approach allows us to group metabolite pairs into being associated due to post-transcriptional or transcriptional regulation, respectively. I showed that the classification of metabolite pairs into those that are associated due to transcriptional or post-transcriptional regulation are in agreement with existing literature and findings from a Bayesian inference approach. The approaches developed, implemented, and investigated in this thesis open novel ways to jointly study metabolomics and transcriptomics data as well as to place metabolic profiles in the network context. The results from these approaches have the potential to provide further insights into the regulatory machinery in a biological system.}, language = {en} } @phdthesis{Luehe2018, author = {L{\"u}he, Josefine}, title = {Das Zusammenspiel von Geschlecht und sozialer Herkunft im Bildungserfolg und in den beruflichen Aspirationen}, doi = {10.25932/publishup-42887}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-428870}, school = {Universit{\"a}t Potsdam}, pages = {198}, year = {2018}, abstract = {Studien zum Bildungserfolg in Deutschland weisen auf verschiedene Ungleichheitsdimensionen hin. So wurde wiederholt ein enger Zusammenhang zwischen der sozialen Herkunft und dem schulischen Bildungserfolg dokumentiert. Des Weiteren stellen auch Geschlechterunterschiede im Bildungserfolg einen vielfach berichteten und sowohl wissenschaftlich als auch gesellschaftlich diskutierten Befund dar. Der großen Anzahl an Studien, die sich jeweils einer dieser Ungleichheitsdimensionen widmen, steht jedoch ein Forschungsbedarf bez{\"u}glich des systematischen Wissens {\"u}ber die Wechselwirkung von Geschlecht und sozialer Herkunft im Bildungserfolg gegen{\"u}ber. Vor diesem Hintergrund hat die vorliegende Arbeit zum Ziel, das Zusammenspiel von Geschlecht und sozialer Herkunft zu untersuchen, wobei sie von zwei {\"u}bergeordneten Fragestellungen geleitet wird, die im Rahmen von vier Teilstudien untersucht werden.Erstens wurde das Zusammenspiel von Geschlecht und sozio{\"o}konomischem Status (SES) in unterschiedlichen Facetten des Bildungserfolges sowie in den Berufsaspirationen analysiert (Teilstudien 1-3). Zweitens wurde untersucht, inwiefern die elterlichen Geschlechterrollenvorstellungen mit den Schulleistungen ihres Kindes assoziiert sind. Vor diesem Hintergrund wurde ebenso der Zusammenhang zwischen den elterlichen Geschlechterrollenvorstellungen und Merkmalen des famili{\"a}ren Hintergrundes analysiert (Teilstudie 4). Zusammenfassend betrachtet weisen die Ergebnisse der Teilstudien auf eine Wechselwirkung von Geschlechtszugeh{\"o}rigkeit und sozialer Herkunft im Bildungserfolg sowie in den beruflichen Aspirationen hin, auch wenn die entsprechenden Effekte eher klein ausfallen. Entgegen der gesellschaftlichen Konnotation von Mathematik als „Jungenfach" stellen die Befunde damit beispielsweise einen Hinweis darauf dar, dass die vielfach zitierten Geschlechterunterschiede in den mathematischen Kompetenzen nicht als „naturgegeben" sondern beeinflussbar verstanden werden k{\"o}nnen. Damit untermauern die Ergebnisse die unter anderem im Rahmen verschiedener Theorien herausgestellte Bedeutsamkeit des Sozialisationskontextes f{\"u}r die Entwicklung der F{\"a}higkeiten und Ziele von Jungen und M{\"a}dchen sowie die im internationalen Vergleich gezeigte Variabilit{\"a}t von Geschlechterunterschieden in Schulleistungen.}, language = {de} } @phdthesis{Hein2018, author = {Hein, Friederike}, title = {Das Recht auf Familiennachzug im Ausl{\"a}nderrecht}, doi = {10.25932/publishup-43264}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-432642}, school = {Universit{\"a}t Potsdam}, pages = {170}, year = {2018}, abstract = {Die Arbeit besch{\"a}ftigt sich mit den aktuellen Regelungen des deutschen Aufenthaltsrechts in Bezug auf die M{\"o}glichkeiten des Familiennachzuges. Es werden Schwachstellen der aktuellen Regelungen aufgezeigt, Ursachen, Rechtfertigungsgr{\"u}nde und m{\"o}gliche L{\"o}sungsans{\"a}tze betrachtet. Schwerpunkt der Betrachtung sind die Konflikte, welche sich unter dem Begriff der Inl{\"a}nderdiskriminierung zusammenfassen lassen. Hierzu wird das Ph{\"a}nomen der Inl{\"a}nderdiskriminierung untersucht und die im Kontext des Familiennachzuges hierzu ergangene Rechtsprechung des EuGH betrachtet. Dabei gilt das Hauptaugenmerk der Figur des grenz{\"u}berschreitenden Bezuges, welche der EuGH im Ergebnis mittlerweile aufgel{\"o}st hat. Als Ergebnis dieses Abschnittes der Arbeit wird festgestellt, dass eine Unterscheidung von Nachzug zu Deutschen oder zu Unionsb{\"u}rgern gegen Gleichheitss{\"a}tze verst{\"o}ßt und aufzuheben ist. Weiterhin betrachtet die Arbeit verschiedene alternative Lebensmodelle neben der klassischen verschiedengeschlechtlichen Ehe. In Bezug auf gleichgeschlechtliche Lebensgemeinschaften werden auch nach Einf{\"u}hrung der „Ehe f{\"u}r alle" weitere Schwachstellen verortet, die vor allem darauf fußen, dass Nachzugsrechte vom Bestehen eines Instituts abh{\"a}ngen, welches in großen Teilen der Welt nicht gibt. In Hinblick auf nichtehelichen Lebensgemeinschaften wird hingegen die geltende Rechtslage als ausreichend betrachtet. Zuletzt betrachtet die Arbeit Ehemodelle, welche im deutschen Recht nicht vorgesehen und anerkannt sind. Dies sind die Zwangs-, Kinder- und Mehrehe. Es wird beleuchtet, wie das deutsche Recht und insbesondere das Aufenthaltsrecht mit diesen Ehen umgeht und welcher Zweck mit den bestehenden Regelungen verfolgt wird. W{\"a}hrend der Gesetzgeber den Schutz der Opfer solcher Eheschließungen vor Augen hatte, kommt die Untersuchung zu dem Ergebnis, dass vielmehr eine weitere Gef{\"a}hrdung eintritt, welche nur zu vermeiden w{\"a}re, wenn auch diese Ehemodelle zun{\"a}chst anerkannt w{\"u}rden und den Opfern im Inland sodann Hilfe angeboten w{\"u}rde. Insgesamt stellt die Arbeit gravierende M{\"a}ngel in menschenrechtlicher Hinsicht im bestehenden Recht des Familiennachzugs fest und schl{\"a}gt eine generelle Neuordnung vor. Die betrachteten Regelungen entsprechen dem Regelungsstand im Juli 2018.}, language = {de} } @phdthesis{Mielke2018, author = {Mielke, Jahel}, title = {Coordination on Green Investment}, doi = {10.25932/publishup-42745}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-427459}, school = {Universit{\"a}t Potsdam}, pages = {viii, 209}, year = {2018}, abstract = {To reach its climate targets, the European Union has to implement a major sustainability transition in the coming decades. While the socio-technical change required for this transition is well discussed in the academic literature, the economics that go along with it are often reduced to a cost-benefit perspective of climate policy measures. By investigating climate change mitigation as a coordination problem, this thesis offers a novel perspective: It integrates the economic and the socio-technical dimension and thus allows to better understand the opportunities of a sustainability transition in Europe. First, a game theoretic framework is developed to illustrate coordination on green or brown investment from an agent perspective. A model based on the coordination game "stag hunt" is used to discuss the influence of narratives and signals for green investment as a means to coordinate expectations towards green growth. Public and private green investment impulses - triggered by credible climate policy measures and targets - serve as an example for a green growth perspective for Europe in line with a sustainability transition. This perspective also embodies a critical view on classical analyses of climate policy measures. Secondly, this analysis is enriched with empirical results derived from stakeholder involvement. In interviews and with a survey among European insurance companies, coordination mechanisms such as market and policy signals are identified and evaluated by their impact on investment strategies for green infrastructure. The latter, here defined as renewable energy, electricity distribution and transmission as well as energy efficiency improvements, is considered a central element of the transition to a low-carbon society. Thirdly, this thesis identifies and analyzes major criticisms raised towards stakeholder involvement in sustainability science. On a conceptual level, different ways of conducting such qualitative research are classified. This conceptualization is then evaluated by scientists, thereby generating empirical evidence on ideals and practices of stakeholder involvement in sustainability science. Through the combination of theoretical and empirical research on coordination problems, this thesis offers several contributions: On the one hand, it outlines an approach that allows to assess the economic opportunities of sustainability transitions. This is helpful for policy makers in Europe that are striving to implement climate policy measures addressing the targets of the Paris Agreement as well as to encourage a shift of investments towards green infrastructure. On the other hand, this thesis enhances the stabilization of the theoretical foundations in sustainability science. Therefore, it can aid researchers who involve stakeholders when studying sustainability transitions.}, language = {en} } @phdthesis{Cheng2018, author = {Cheng, Xiao}, title = {Controlled solvent vapor annealing of block copolymer films}, doi = {10.25932/publishup-42417}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-424179}, school = {Universit{\"a}t Potsdam}, pages = {X, 166}, year = {2018}, abstract = {This project was focused on exploring the phase behavior of poly(styrene)187000-block-poly(2-vinylpyridine)203000 (SV390) with high molecular weight (390 kg/mol) in thin films, in which the self-assembly of block copolymers (BCPs) was realized via thermo-solvent annealing. The advanced processing technique of solvent vapor treatment provides controlled and stable conditions. In Chapter 3, the factors to influence the annealing process and the swelling behavior of homopolymers are presented and discussed. The swelling behavior of BCP in films is controlled by the temperature of the vapor and of the substrate, on one hand, and variation of the saturation of the solvent vapor atmosphere (different solvents), on the other hand. Additional factors like the geometry and material of the chamber, the type of flow inside the chamber etc. also influence the reproducibility and stability of the processing. The slightly selective solvent vapor of chloroform gives 10\% more swelling of P2VP than PS in films with thickness of ~40 nm. The tunable morphology in ultrathin films of high molecular weight BCP (SV390) was investigated in Chapter 4. First, the swelling behavior can be precisely tuned by temperature and/or vapor flow separately, which provided information for exploring the multiple-parameter-influenced segmental chain mobility of polymer films. The equilibrium state of SV390 in thin films influenced by temperature was realized at various temperatures with the same degree of swelling. Various methods including characterization with SFM, metallization and RIE were used to identify the morphology of films as porous half-layer with PS dots and P2VP matrix. The kinetic investigations demonstrate that on substrates with either weak or strong interaction the original morphology of the BCP with high molecular weight is changed very fast within 5 min, and the further annealing serves for annihilation of defects. The morphological development of symmetric BCP in films with thickness increasing from half-layer to one-layer influenced by confinement factors of gradient film thicknesses and various surface properties of substrates was studied in Chapter 5. SV390 and SV99 films show bulk lamella-forming morphology after slightly selective solvent vapor (chloroform) treatment. SV99 films show cylinder-forming morphology under strongly selective solvent vapor (toluene) treatment since the asymmetric structure (caused by toluene uptake in PS blocks only) of SV99 block copolymer during annealing. Both kinds of morphology (lamella and cylinder) are influenced by the film thickness. The annealed morphology of SV390 and SV99 influenced by the combination of confined film and substrate property is similar to the morphology on flat silicon wafers. In this chapter the gradients in the film thickness and surface properties of the substrates with regard to their influence on the morphological development in thin BCP films are presented. Directed self-assembly (graphoepitaxy) of this SV390 was also investigated to compare with systematically reported SV99. In Chapter 6 an approach to induced oriented microphase separation in thick block copolymer films via treatment with the oriented vapor flow using mini-extruder is envisaged to be an alternative to existing methodologies, e.g. via non-solvent-induced phase separation. The preliminary tests performed in this study confirm potential perspective of this method, which alters the structure through the bulk of the film (as revealed by SAXS measurements), but more detailed studies have to be conducted in order to optimize the preparation.}, language = {en} } @phdthesis{Richter2018, author = {Richter, Rico}, title = {Concepts and techniques for processing and rendering of massive 3D point clouds}, doi = {10.25932/publishup-42330}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-423304}, school = {Universit{\"a}t Potsdam}, pages = {v, 131}, year = {2018}, abstract = {Remote sensing technology, such as airborne, mobile, or terrestrial laser scanning, and photogrammetric techniques, are fundamental approaches for efficient, automatic creation of digital representations of spatial environments. For example, they allow us to generate 3D point clouds of landscapes, cities, infrastructure networks, and sites. As essential and universal category of geodata, 3D point clouds are used and processed by a growing number of applications, services, and systems such as in the domains of urban planning, landscape architecture, environmental monitoring, disaster management, virtual geographic environments as well as for spatial analysis and simulation. While the acquisition processes for 3D point clouds become more and more reliable and widely-used, applications and systems are faced with more and more 3D point cloud data. In addition, 3D point clouds, by their very nature, are raw data, i.e., they do not contain any structural or semantics information. Many processing strategies common to GIS such as deriving polygon-based 3D models generally do not scale for billions of points. GIS typically reduce data density and precision of 3D point clouds to cope with the sheer amount of data, but that results in a significant loss of valuable information at the same time. This thesis proposes concepts and techniques designed to efficiently store and process massive 3D point clouds. To this end, object-class segmentation approaches are presented to attribute semantics to 3D point clouds, used, for example, to identify building, vegetation, and ground structures and, thus, to enable processing, analyzing, and visualizing 3D point clouds in a more effective and efficient way. Similarly, change detection and updating strategies for 3D point clouds are introduced that allow for reducing storage requirements and incrementally updating 3D point cloud databases. In addition, this thesis presents out-of-core, real-time rendering techniques used to interactively explore 3D point clouds and related analysis results. All techniques have been implemented based on specialized spatial data structures, out-of-core algorithms, and GPU-based processing schemas to cope with massive 3D point clouds having billions of points. All proposed techniques have been evaluated and demonstrated their applicability to the field of geospatial applications and systems, in particular for tasks such as classification, processing, and visualization. Case studies for 3D point clouds of entire cities with up to 80 billion points show that the presented approaches open up new ways to manage and apply large-scale, dense, and time-variant 3D point clouds as required by a rapidly growing number of applications and systems.}, language = {en} } @phdthesis{Alhajturki2018, author = {Alhajturki, Dema}, title = {Characterization of altered inflorescence architecture in Arabidopsis thaliana BG-5 x Kro-0 hybrid}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-420934}, school = {Universit{\"a}t Potsdam}, pages = {109}, year = {2018}, abstract = {A reciprocal cross between two A. thaliana accessions, Kro-0 (Krotzenburg, Germany) and BG-5 (Seattle, USA), displays purple rosette leaves and dwarf bushy phenotype in F1 hybrids when grown at 17 °C and a parental-like phenotype when grown at 21 °C. This F1 temperature-dependent-dwarf-bushy phenotype is characterized by reduced growth of the primary stem together with an increased number of branches. The reduced stem growth was the strongest at the first internode. In addition, we found that a temperature switch from 21 °C to 17 °C induced the phenotype only before the formation of the first internode of the stem. Similarly, the F1 dwarf-bushy phenotype could not be reversed when plants were shifted from 17 °C to 21 °C after the first internode was formed. Metabolic analysis showed that the F1 phenotype was associated with a significant upregulation of anthocyanin(s), kaempferol(s), salicylic acid, jasmonic acid and abscisic acid. As it has been previously shown that the dwarf-bushy phenotype is linked to two loci, one on chromosome 2 from Kro-0 and one on chromosome 3 from BG-5, an artificial micro-RNA approach was used to investigate the necessary genes on these intervals. From the results obtained, it was found that two genes, AT2G14120 that encodes for a DYNAMIN RELATED PROTEIN3B and AT2G14100 that encodes a member of the Cytochrome P450 family protein CYP705A13, were necessary for the appearance of the F1 phenotype on chromosome 2. It was also discovered that AT3G61035 that encodes for another cytochrome P450 family protein CYP705A13 and AT3G60840 that encodes for a MICROTUBULE-ASSOCIATED PROTEIN65-4 on chromosome 3 were both necessary for the induction of the F1 phenotype. To prove the causality of these genes, genomic constructs of the Kro-0 candidate genes on chromosome 2 were transferred to BG-5 and genomic constructs of the chromosome 3 candidate genes from BG-5 were transferred to Kro-0. The T1 lines showed that these genes are not sufficient alone to induce the phenotype. In addition to the F1 phenotype, more severe phenotypes were observed in the F2 generations that were grouped into five different phenotypic classes. Whilst seed yield was comparable between F1 hybrids and parental lines, three phenotypic classes in the F2 generation exhibited hybrid breakdown in the form of reproductive failure. This F2 hybrid breakdown was less sensitive to temperature and showed a dose-dependent effect of the loci involved in F1 phenotype. The severest class of hybrid breakdown phenotypes was observed only in the population of backcross with the parent Kro-0, which indicates a stronger contribution of the BG-5 allele when compared to the Kro-0 allele on the hybrid breakdown phenotypes. Overall, the findings of my thesis provide a further understanding of the genetic and metabolic factors underlying altered shoot architecture in hybrid dysfunction.}, language = {en} } @phdthesis{Behrens2018, author = {Behrens, Ricarda}, title = {Causes for slow weathering and erosion in the steep, warm, monsoon-subjected Highlands of Sri Lanka}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-408503}, school = {Universit{\"a}t Potsdam}, pages = {ix, 107, XXIV}, year = {2018}, abstract = {In the Highlands of Sri Lanka, erosion and chemical weathering rates are among the lowest for global mountain denudation. In this tropical humid setting, highly weathered deep saprolite profiles have developed from high-grade metamorphic charnockite during spheroidal weathering of the bedrock. The spheroidal weathering produces rounded corestones and spalled rindlets at the rock-saprolite interface. I used detailed textural, mineralogical, chemical, and electron-microscopic (SEM, FIB, TEM) analyses to identify the factors limiting the rate of weathering front advance in the profile, the sequence of weathering reactions, and the underlying mechanisms. The first mineral attacked by weathering was found to be pyroxene initiated by in situ Fe oxidation, followed by in situ biotite oxidation. Bulk dissolution of the primary minerals is best described with a dissolution - re-precipitation process, as no chemical gradients towards the mineral surface and sharp structural boundaries are observed at the nm scale. Only the local oxidation in pyroxene and biotite is better described with an ion by ion process. The first secondary phases are oxides and amorphous precipitates from which secondary minerals (mainly smectite and kaolinite) form. Only for biotite direct solid state transformation to kaolinite is likely. The initial oxidation of pyroxene and biotite takes place in locally restricted areas and is relatively fast: log J = -11 molmin/(m2 s). However, calculated corestone-scale mineral oxidation rates are comparable to corestone-scale mineral dissolution rates: log R = -13 molpx/(m2 s) and log R = -15 molbt/(m2 s). The oxidation reaction results in a volume increase. Volumetric calculations suggest that this observed oxidation leads to the generation of porosity due to the formation of micro-fractures in the minerals and the bedrock allowing for fluid transport and subsequent dissolution of plagioclase. At the scale of the corestone, this fracture reaction is responsible for the larger fractures that lead to spheroidal weathering and to the formation of rindlets. Since these fractures have their origin from the initial oxidational induced volume increase, oxidation is the rate limiting parameter for weathering to take place. The ensuing plagioclase weathering leads to formation of high secondary porosity in the corestone over a distance of only a few cm and eventually to the final disaggregation of bedrock to saprolite. As oxidation is the first weathering reaction, the supply of O2 is a rate-limiting factor for chemical weathering. Hence, the supply of O2 and its consumption at depth connects processes at the weathering front with erosion at the surface in a feedback mechanism. The strength of the feedback depends on the relative weight of advective versus diffusive transport of O2 through the weathering profile. The feedback will be stronger with dominating diffusive transport. The low weathering rate ultimately depends on the transport of O2 through the whole regolith, and on lithological factors such as low bedrock porosity and the amount of Fe-bearing primary minerals. In this regard the low-porosity charnockite with its low content of Fe(II) bearing minerals impedes fast weathering reactions. Fresh weatherable surfaces are a pre-requisite for chemical weathering. However, in the case of the charnockite found in the Sri Lankan Highlands, the only process that generates these surfaces is the fracturing induced by oxidation. Tectonic quiescence in this region and low pre-anthropogenic erosion rate (attributed to a dense vegetation cover) minimize the rejuvenation of the thick and cohesive regolith column, and lowers weathering through the feedback with erosion.}, language = {en} } @phdthesis{Stolle2018, author = {Stolle, Amelie}, title = {Catastrophic Sediment Pulses in the Pokhara Valley, Nepal}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-413341}, school = {Universit{\"a}t Potsdam}, pages = {XVII, 173}, year = {2018}, abstract = {Fluvial terraces, floodplains, and alluvial fans are the main landforms to store sediments and to decouple hillslopes from eroding mountain rivers. Such low-relief landforms are also preferred locations for humans to settle in otherwise steep and poorly accessible terrain. Abundant water and sediment as essential sources for buildings and infrastructure make these areas amenable places to live at. Yet valley floors are also prone to rare and catastrophic sedimentation that can overload river systems by abruptly increasing the volume of sediment supply, thus causing massive floodplain aggradation, lateral channel instability, and increased flooding. Some valley-fill sediments should thus record these catastrophic sediment pulses, allowing insights into their timing, magnitude, and consequences. This thesis pursues this theme and focuses on a prominent ~150 km2 valley fill in the Pokhara Valley just south of the Annapurna Massif in central Nepal. The Pokhara Valley is conspicuously broad and gentle compared to the surrounding dissected mountain terrain, and is filled with locally more than 70 m of clastic debris. The area's main river, Seti Khola, descends from the Annapurna Sabche Cirque at 3500-4500 m asl down to 900 m asl where it incises into this valley fill. Humans began to settle on this extensive fan surface in the 1750's when the Trans-Himalayan trade route connected the Higher Himalayas, passing Pokhara city, with the subtropical lowlands of the Terai. High and unstable river terraces and steep gorges undermined by fast flowing rivers with highly seasonal (monsoon-driven) discharge, a high earthquake risk, and a growing population make the Pokhara Valley an ideal place to study the recent geological and geomorphic history of its sediments and the implication for natural hazard appraisals. The objective of this thesis is to quantify the timing, the sedimentologic and geomorphic processes as well as the fluvial response to a series of strong sediment pulses. I report diagnostic sedimentary archives, lithofacies of the fan terraces, their geochemical provenance, radiocarbon-age dating and the stratigraphic relationship between them. All these various and independent lines of evidence show consistently that multiple sediment pulses filled the Pokhara Valley in medieval times, most likely in connection with, if not triggered by, strong seismic ground shaking. The geomorphic and sedimentary evidence is consistent with catastrophic fluvial aggradation tied to the timing of three medieval Himalayan earthquakes in ~1100, 1255, and 1344 AD. Sediment provenance and calibrated radiocarbon-age data are the key to distinguish three individual sediment pulses, as these are not evident from their sedimentology alone. I explore various measures of adjustment and fluvial response of the river system following these massive aggradation pulses. By using proxies such as net volumetric erosion, incision and erosion rates, clast provenance on active river banks, geomorphic markers such as re-exhumed tree trunks in growth position, and knickpoint locations in tributary valleys, I estimate the response of the river network in the Pokhara Valley to earthquake disturbance over several centuries. Estimates of the removed volumes since catastrophic valley filling began, require average net sediment yields of up to 4200 t km-2 yr-1 since, rates that are consistent with those reported for Himalayan rivers. The lithological composition of active channel-bed load differs from that of local bedrock material, confirming that rivers have adjusted 30-50\% depending on data of different tributary catchments, locally incising with rates of 160-220 mm yr-1. In many tributaries to the Seti Khola, most of the contemporary river loads come from a Higher Himalayan source, thus excluding local hillslopes as sources. This imbalance in sediment provenance emphasizes how the medieval sediment pulses must have rapidly traversed up to 70 km downstream to invade the downstream reaches of the tributaries up to 8 km upstream, thereby blocking the local drainage and thus reinforcing, or locally creating new, floodplain lakes still visible in the landscape today. Understanding the formation, origin, mechanism and geomorphic processes of this valley fill is crucial to understand the landscape evolution and response to catastrophic sediment pulses. Several earthquake-triggered long-runout rock-ice avalanches or catastrophic dam burst in the Higher Himalayas are the only plausible mechanisms to explain both the geomorphic and sedimentary legacy that I document here. In any case, the Pokhara Valley was most likely hit by a cascade of extremely rare processes over some two centuries starting in the early 11th century. Nowhere in the Himalayas do we find valley fills of comparable size and equally well documented depositional history, making the Pokhara Valley one of the most extensively dated valley fill in the Himalayas to date. Judging from the growing record of historic Himalayan earthquakes in Nepal that were traced and dated in fault trenches, this thesis shows that sedimentary archives can be used to directly aid reconstructions and predictions of both earthquake triggers and impacts from a sedimentary-response perspective. The knowledge about the timing, evolution, and response of the Pokhara Valley and its river system to earthquake triggered sediment pulses is important to address the seismic and geomorphic risk for the city of Pokhara. This thesis demonstrates how geomorphic evidence on catastrophic valley infill can help to independently verify paleoseismological fault-trench records and may initiate re-thinking on post-seismic hazard assessments in active mountain regions.}, language = {en} } @phdthesis{Witt2018, author = {Witt, Tanja Ivonne}, title = {Camera Monitoring at volcanoes}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-421073}, school = {Universit{\"a}t Potsdam}, pages = {viii, 140}, year = {2018}, abstract = {Basaltic fissure eruptions, such as on Hawai'i or on Iceland, are thought to be driven by the lateral propagation of feeder dikes and graben subsidence. Associated solid earth processes, such as deformation and structural development, are well studied by means of geophysical and geodetic technologies. The eruptions themselves, lava fountaining and venting dynamics, in turn, have been much less investigated due to hazardous access, local dimension, fast processes, and resulting poor data availability. This thesis provides a detailed quantitative understanding of the shape and dynamics of lava fountains and the morphological changes at their respective eruption sites. For this purpose, I apply image processing techniques, including drones and fixed installed cameras, to the sequence of frames of video records from two well-known fissure eruptions in Hawai'i and Iceland. This way I extract the dimensions of multiple lava fountains, visible in all frames. By putting these results together and considering the acquisition times of the frames I quantify the variations in height, width and eruption velocity of the lava fountains. Then I analyse these time-series in both time and frequency domains and investigate the similarities and correlations between adjacent lava fountains. Following this procedure, I am able to link the dynamics of the individual lava fountains to physical parameters of the magma transport in the feeder dyke of the fountains. The first case study in this thesis focuses on the March 2011 Pu'u'O'o eruption, Hawai'i, where a continuous pulsating behaviour at all eight lava fountains has been observed. The lava fountains, even those from different parts of the fissure that are closely connected, show a similar frequency content and eruption behaviour. The regular pattern in the heights of lava fountain suggests a controlling process within the magma feeder system like a hydraulic connection in the underlying dyke, affecting or even controlling the pulsating behaviour. The second case study addresses the 2014-2015 Holuhraun fissure eruption, Iceland. In this case, the feeder dyke is highlighted by the surface expressions of graben-like structures and fault systems. At the eruption site, the activity decreases from a continuous line of fire of ~60 vents to a limited number of lava fountains. This can be explained by preferred upwards magma movements through vertical structures of the pre-eruptive morphology. Seismic tremors during the eruption reveal vent opening at the surface and/or pressure changes in the feeder dyke. The evolving topography of the cinder cones during the eruption interacts with the lava fountain behaviour. Local variations in the lava fountain height and width are controlled by the conduit diameter, the depth of the lava pond and the shape of the crater. Modelling of the fountain heights shows that long-term eruption behaviour is controlled mainly by pressure changes in the feeder dyke. This research consists of six chapters with four papers, including two first author and two co-author papers. It establishes a new method to analyse lava fountain dynamics by video monitoring. The comparison with the seismicity, geomorphologic and structural expressions of fissure eruptions shows a complex relationship between focussed flow through dykes, the morphology of the cinder cones, and the lava fountain dynamics at the vents of a fissure eruption.}, language = {en} } @phdthesis{Khalil2018, author = {Khalil, Sara}, title = {Boundary Value Problems on Manifolds with Singularities}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-419018}, school = {Universit{\"a}t Potsdam}, pages = {10, 160}, year = {2018}, abstract = {In the thesis there are constructed new quantizations for pseudo-differential boundary value problems (BVPs) on manifolds with edge. The shape of operators comes from Boutet de Monvel's calculus which exists on smooth manifolds with boundary. The singular case, here with edge and boundary, is much more complicated. The present approach simplifies the operator-valued symbolic structures by using suitable Mellin quantizations on infinite stretched model cones of wedges with boundary. The Mellin symbols themselves are, modulo smoothing ones, with asymptotics, holomorphic in the complex Mellin covariable. One of the main results is the construction of parametrices of elliptic elements in the corresponding operator algebra, including elliptic edge conditions.}, language = {en} } @phdthesis{Sakowski2018, author = {Sakowski, Fabian}, title = {Bodennutzung in der New Economic Geography}, series = {Potsdamer Schriften zur Raumwirtschaft}, journal = {Potsdamer Schriften zur Raumwirtschaft}, number = {7}, publisher = {Universit{\"a}tsverlag Potsdam}, address = {Potsdam}, isbn = {978-3-86956-426-5}, issn = {2190-8702}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-413737}, school = {Universit{\"a}t Potsdam}, pages = {xiv, 290}, year = {2018}, abstract = {Mit der New Economic Geography (NEG) kann die Verteilung von Unternehmen und Arbeitskr{\"a}ften auf Regionen modellhaft diskutiert werden. In diesem Beitrag wird untersucht, welche r{\"a}umlichen Verteilungen der mobilen Arbeitskr{\"a}fte und Unternehmen in einem NEG-Modellansatz resultieren, wenn die Gr{\"o}ße einer Region und damit der ihr zur Verf{\"u}gung stehende Boden, die zu {\"u}berwindende Distanz f{\"u}r den G{\"u}tertransport innerhalb der Regionen, sowie Bodennutzungskonkurrenzen zwischen Wohnen, Industrie und Landwirtschaft ber{\"u}cksichtigt werden. Auch wird der Frage nachgegangen, welche Wohlfahrtswirkungen hierbei resultieren.}, language = {de} } @phdthesis{Genderjahn2018, author = {Genderjahn, Steffi}, title = {Biosignatures of Present and Past Microbial Life in Southern African Geoarchives}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-410110}, school = {Universit{\"a}t Potsdam}, pages = {XI, 166, xxii}, year = {2018}, abstract = {Global climate change is one of the greatest challenges of the 21st century, with influence on the environment, societies, politics and economies. The (semi-)arid areas of Southern Africa already suffer from water scarcity. There is a great variety of ongoing research related to global climate history but important questions on regional differences still exist. In southern African regions terrestrial climate archives are rare, which makes paleoclimate studies challenging. Based on the assumption that continental pans (sabkhas) represent a suitable geo-archive for the climate history, two different pans were studied in the southern and western Kalahari Desert. A combined approach of molecular biological and biogeochemical analyses is utilized to investigate the diversity and abundance of microorganisms and to trace temporal and spatial changes in paleoprecipitation in arid environments. The present PhD thesis demonstrates the applicability of pan sediments as a late Quaternary geo-archive based on microbial signature lipid biomarkers, such as archaeol, branched and isoprenoid glycerol dialkyl glycerol tetraethers (GDGTs) as well as phospholipid fatty acids (PLFA). The microbial signatures contained in the sediment provide information on the current or past microbial community from the Last Glacial Maximum to the recent epoch, the Holocene. The results are discussed in the context of regional climate evolution in southwestern Africa. The seasonal shift of the Innertropical Convergence Zone (ITCZ) along the equator influences the distribution of precipitation- and climate zones. The different expansion of the winter- and summer rainfall zones in southern Africa was confirmed by the frequency of certain microbial biomarkers. A period of increased precipitation in the south-western Kalahari could be described as a result of the extension of the winter rainfall zone during the last glacial maximum (21 ± 2 ka). Instead a period of increased paleoprecipitation in the western Kalahari was indicated during the Late Glacial to Holocene transition. This was possibly caused by a southwestern shift in the position of the summer rainfall zone associated to the southward movement of the ITCZ. Furthermore, for the first time this study characterizes the bacterial and archaeal life based on 16S rRNA gene high-throughput sequencing in continental pan sediments and provides an insight into the recent microbial community structure. Near-surface processes play an important role for the modern microbial ecosystem in the pans. Water availability as well as salinity might determine the abundance and composition of the microbial communities. The microbial community of pan sediments is dominated by halophilic and dry-adapted archaea and bacteria. Frequently occurring microorganisms such as, Halobacteriaceae, Bacillus and Gemmatimonadetes are described in more detail in this study.}, language = {en} } @phdthesis{Klimczak2018, author = {Klimczak, Franziska}, title = {Bildlichkeit und Metaphorik in sp{\"a}tmittelalterlichen Fastnachtspielen des 15. Jahrhunderts}, isbn = {978-3-86956-408-1}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-397320}, school = {Universit{\"a}t Potsdam}, pages = {208}, year = {2018}, abstract = {Die Dissertation untersucht die Sexualmetaphorik im N{\"u}rnberger Fastnachtspiel des 15. Jahrhunderts und w{\"a}hlt als Textgrundlage die Ausgabe der N{\"u}rnberger Fastnachtspiele von Adelbert von Keller als einzig vollst{\"a}ndige Sammlung. Anliegen der Dissertation ist es, die Einzigartigkeit des Wortschatzes des Fastnachtspiels herauszuarbeiten, indem mit Fokus auf die Bildhaftigkeit und die Metaphorik der obsz{\"o}nen Redeweise {\"u}ber deren Aussage- und Wirkkraft im historischen Fastnachtspielkontext reflektiert wird. Wie die Metapher gezielt tabuisierte, intime Inhalte zum Zwecke der Komik legitimiert, wird erst theoretisch ergr{\"u}ndet und dann in einer Interpretation der sprachlichen Gestaltung von Sexualit{\"a}t und Obsz{\"o}nit{\"a}t mit Blick auf den soziokulturellen Hintergrund des N{\"u}rnberger Fastnachtspiels kritisch reflektiert. In einer interdisziplin{\"a}ren Ann{\"a}herung werden zun{\"a}chst sowohl Erkenntnisse und Theorien aus der Fastnachtspiel- und Mittelalterforschung als auch theoretische Ans{\"a}tze aus der Metaphorologie und der Komikforschung zusammengetragen und diskutiert. Im Rahmen des breitgef{\"a}cherten, wissenschaftlichen Diskurses zu den Fastnachtspielen wird das N{\"u}rnberger Fastnachtspiel aus inhaltlicher, funktionaler, genderbezogener, kulturgeschichtlicher und sprachlicher Perspektive beleuchtet, um ein besseres Verst{\"a}ndnis der Sprache des Fastnachtspiels zu erlangen. Im n{\"a}chsten Schritt werden das mittelalterliche Ehe- und Familienleben und die soziale und rechtliche Stellung von Mann und Frau analysiert, indem theologisch-normativer und literarischer Ehediskurs einander gegen{\"u}bergestellt und gattungsspezifisch untersucht werden. So k{\"o}nnen Logiken und Verfahrensweisen in der mittelalterlichen Alltags-, Glaubens- und Rechtspraxis aufgedeckt werden. Dadurch ist es m{\"o}glich, die Inszenierungen des K{\"o}rpers im Fastnachtspiel einzusch{\"a}tzen, die die mittelalterliche Sexualmoral verhandeln und so mannigfaltige Bilder und Vorstellungen von Mann und Frau entwerfen. Anschließend wird in der Diskussion relevanter Metapherntheorien ergr{\"u}ndet, wie die metaphorische Sprache dabei den obsz{\"o}nen Inhalten gleichzeitig die T{\"u}r {\"o}ffnet und sie auf Distanz h{\"a}lt. Bei der Betrachtung poststrukturalistischer, erkenntnistheoretischer, kognitiver, semantischer und philosophischer Theorien zur Beschreibung der Arbeits- und Wirkweise der Metapher erweisen sich insbesondere analogieorientierte und funktionale Ans{\"a}tze als gewinnbringend, weil sie die Kontextualisierung der Metapher als bindend voraussetzen und sie als komplexes, metakognitives Ph{\"a}nomen diskutieren, das auf Interaktions- und {\"U}bertragungsprozessen beruht. Sodann werden die vielf{\"a}ltigen Anl{\"a}sse, sozialen Formen und Funktionen des Lachens in der mittelalterlichen Gesellschaft n{\"a}her in den Blick genommen, um den komisch-derbsinnlichen Duktus der Fastnachtspiele nachvollziehen zu k{\"o}nnen. Mit der Bewusstmachung wiederkehrender Elemente und Muster des Komischen kann der Unterhaltungswert der Fastnachtspielsprache exemplarisch verdeutlicht werden. Die sich anschließende umfassende Interpretation der Fastnachtspiele wird methodisch angeleitet durch die Theorie der bildlichen Rede von Hans Georg Coenen. Er bleibt mit seinen Analogiedefinitionen der klassischen Rhetorik verpflichtet und unterscheidet unter anderem „kreative", „konventionalisierte" und „lexikalisierte" Metaphern. Bei der außerordentlichen Vielfalt sexualmetaphorischer Ausdrucksweisen liegt der Fokus auf den Darstellungen der Geschlechtsorgane von Mann und Frau und dem Koitus. Die Verfasserin gelangt zu folgenden Ergebnissen: Die Metapher sorgt durch ihre bildgestaltende Vermittlung jeweils daf{\"u}r, dass der sexuelle Inhalt darstellbar wird, ohne jedoch in unmissverst{\"a}ndlicher Direktheit auf den Betrachter zu treffen. Ob sie mit ihren allt{\"a}glichen, meist b{\"a}uerlichen Bildmotiven f{\"u}r die Schamsph{\"a}re {\"u}ber- oder untertreibt, abwertet oder aufwertet, verh{\"u}llt oder entlarvt - in jedweder Form und Gestalt kann die Metapher den sexuellen Inhalt {\"a}sthetisieren. Weil sie ihn unter neuer oder anderer Perspektive betrachtet, entr{\"u}ckt sie ihn formal. Damit erscheint das Sprechen {\"u}ber Sexualit{\"a}t in der metaphorischen Rede wie auf Abstand gerechtfertigt und das Ausmaß bzw. {\"U}bermaß der Inszenierung von Sexualit{\"a}t im Fastnachtspiel {\"u}berhaupt erst m{\"o}glich. H{\"a}ufig werden Bilder vom Penis als Esel, von der Vagina als Wiese und vom Koitus als Speerkampf entworfen. Die Metapher stellt damit gewohnte Vorstellungen von Mann und Frau mitsamt den normativ gesetzten Erwartungen und Strukturen im Eheleben auf den Kopf. Das kann als obsz{\"o}n und unanst{\"a}ndig, aber auch als am{\"u}sant empfunden worden sein und heute noch empfunden werden. Immer bleibt die Metapher dabei ambigue. In ihrer mehrkanaligen Wirkweise, ihrer innovativen Kraft und auch in ihrer Widerspr{\"u}chlichkeit liegen ihre dichterische Begabung und ihre Qualit{\"a}t zur Komisierung. Damit stellt sich die kunstfertige Sprache des Fastnachtspiels der K{\"o}rperlichkeit der Spielinhalte entgegen. Die Dissertation demonstriert das innovative, normkritische Potenzial der Fastnachtspielsprache, die sie als eine Poetik der Ambiguit{\"a}t lesbar und als einen Schatz an vielf{\"a}ltigen und differenzierten Ausdrucksweisen f{\"u}r die Schamsph{\"a}re wertsch{\"a}tzbar macht. Damit leistet die Arbeit einen wichtigen Beitrag zur sprach- und literaturwissenschaftlichen Analyse des N{\"u}rnberger Fastnachtsspiels und zu einem differenzierteren Verst{\"a}ndnis von dessen kulturgeschichtlicher Bedeutung.}, language = {de} } @phdthesis{Codutti2018, author = {Codutti, Agnese}, title = {Behavior of magnetic microswimmers}, doi = {10.25932/publishup-42297}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-422976}, school = {Universit{\"a}t Potsdam}, pages = {iv, 142}, year = {2018}, abstract = {Microswimmers, i.e. swimmers of micron size experiencing low Reynolds numbers, have received a great deal of attention in the last years, since many applications are envisioned in medicine and bioremediation. A promising field is the one of magnetic swimmers, since magnetism is biocom-patible and could be used to direct or actuate the swimmers. This thesis studies two examples of magnetic microswimmers from a physics point of view. The first system to be studied are magnetic cells, which can be magnetic biohybrids (a swimming cell coupled with a magnetic synthetic component) or magnetotactic bacteria (naturally occurring bacteria that produce an intracellular chain of magnetic crystals). A magnetic cell can passively interact with external magnetic fields, which can be used for direction. The aim of the thesis is to understand how magnetic cells couple this magnetic interaction to their swimming strategies, mainly how they combine it with chemotaxis (the ability to sense external gradient of chemical species and to bias their walk on these gradients). In particular, one open question addresses the advantage given by these magnetic interactions for the magnetotactic bacteria in a natural environment, such as porous sediments. In the thesis, a modified Active Brownian Particle model is used to perform simulations and to reproduce experimental data for different systems such as bacteria swimming in the bulk, in a capillary or in confined geometries. I will show that magnetic fields speed up chemotaxis under special conditions, depending on parameters such as their swimming strategy (run-and-tumble or run-and-reverse), aerotactic strategy (axial or polar), and magnetic fields (intensities and orientations), but it can also hinder bacterial chemotaxis depending on the system. The second example of magnetic microswimmer are rigid magnetic propellers such as helices or random-shaped propellers. These propellers are actuated and directed by an external rotating magnetic field. One open question is how shape and magnetic properties influence the propeller behavior; the goal of this research field is to design the best propeller for a given situation. The aim of the thesis is to propose a simulation method to reproduce the behavior of experimentally-realized propellers and to determine their magnetic properties. The hydrodynamic simulations are based on the use of the mobility matrix. As main result, I propose a method to match the experimental data, while showing that not only shape but also the magnetic properties influence the propellers swimming characteristics.}, language = {en} } @phdthesis{Kraft2018, author = {Kraft, Frederik}, title = {Be Creative, Now!}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-414009}, school = {Universit{\"a}t Potsdam}, pages = {VII, 230}, year = {2018}, abstract = {Purpose - This thesis set out to explore, describe, and evaluate the reality behind the rhetoric of freedom and control in the context of creativity. The overarching subject is concerned with the relationship between creativity, freedom, and control, considering freedom is also seen as an element of control to manage creativity. Design/methodology/approach - In-depth qualitative data gathered from at two innovative start-ups. Two ethnographic studies were conducted. The data are based on participatory observations, interviews, and secondary sources, each of which included a three months field study and a total of 41 interviews from both organizations. Findings - The thesis provides explanations for the practice of freedom and the control of creativity within organizations and expands the existing theory of neo-normative control. The findings indicate that organizations use complex control systems that allow a high degree of freedom that paradoxically leads to more control. Freedom is a cover of control, which in turn leads to creativity. Covert control even results in the responsibility to be creative outside working hours. Practical implications - Organizations, which rely on creativity might use the results of this thesis. Positive workplace control of creativity provides both freedom and structure for creative work. While freedom leads to organizational members being more motivated and committing themselves more strongly to their and the organization's goals, and a specific structure also helps to provide the requirements for creativity. Originality/value - The thesis provides an insight into an approach to workplace control, which has mostly neglected in creativity research and proposes a modified concept of neo-normative control. It serves to provide a further understanding of freedom for creativity and to challenge the liberal claims of new control forms.}, language = {en} } @phdthesis{Pavleski2018, author = {Pavleski, Stefan}, title = {Arbeitslosigkeit in S{\"u}dosteuropa im Kontext der EU-Integration}, series = {Potsdam Economic Studies}, journal = {Potsdam Economic Studies}, number = {7}, publisher = {Universit{\"a}tsverlag Potsdam}, address = {Potsdam}, isbn = {978-3-86956-421-0}, issn = {2196-8691}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-404287}, school = {Universit{\"a}t Potsdam}, pages = {xxi, 263}, year = {2018}, abstract = {Diese Arbeit besteht aus drei Aufs{\"a}tzen. Der erste Aufsatz („Die Arbeitsmarktpolitik in S{\"u}dosteuropa: Von der Transformation bis zur EU-Integration") er{\"o}rtert die wirtschaftlichen und politischen Rahmenbedingungen in S{\"u}dosteuropa und die damit einhergehenden Entwicklungen auf den jeweiligen Arbeitsm{\"a}rkten seit 1991. Im Fokus steht dabei der Einfluss der Arbeitslosigkeit (als systemunabh{\"a}ngiges Problem) auf den EU-Integrationsprozess in den jugoslawischen Nachfolgestaaten und Albanien. Welchen Einfluss haben der qualifikatorische und regionale Mismatch auf die Arbeitslosigkeit in Kroatien? Um diese Frage zu beantworten, wird im zweiten Kapitel dieser Arbeit („Arbeitslosigkeit im Transformationsprozess: Qualifikatorischer und regionaler Mismatch in Kroatien") der Mismatch sowohl statisch mit Mismatch-Indikatoren als auch dynamisch im Rahmen der Matching-Funktion er{\"o}rtert. Unter Anwendung von Paneldaten f{\"u}r neun Berufsgruppen und 21 Regionen im Zeitraum zwischen Januar 2004 und Juni 2015 wird in diesem Kapitel mithilfe von Fixed-Effects-Modellen dieser Einfluss gesch{\"a}tzt. F{\"u}hrt die Anpassung der Arbeitslosenversicherungsgesetze an die EU-Standards zu einer Verbesserung der Arbeitsmarktergebnisse in den Staaten S{\"u}dosteuropas? Mit Hilfe von Paneldaten f{\"u}r den Zeitraum 1996-2014 wird f{\"u}r f{\"u}nf s{\"u}dosteurop{\"a}ische Staaten (Albanien, Kroatien, Mazedonien, Montenegro und Serbien) dieser Einfluss im Rahmen eines Differenz-in-Differenzen-Modells im dritten Aufsatz („Unvollst{\"a}ndige Integration: Eine Differenz-in-Differenzen-Analyse der s{\"u}dosteurop{\"a}ischen Arbeitsm{\"a}rkte") gesch{\"a}tzt.}, language = {de} } @phdthesis{Ma2018, author = {Ma, Siyuan}, title = {Analysis of Teukolsky equations on slowly rotating Kerr spacetimes}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-414781}, school = {Universit{\"a}t Potsdam}, pages = {vi, 89}, year = {2018}, abstract = {In this thesis, we treat the extreme Newman-Penrose components of both the Maxwell field (s=±1) and the linearized gravitational perturbations (or "linearized gravity" for short) (s=±2) in the exterior of a slowly rotating Kerr black hole. Upon different rescalings, we can obtain spin s components which satisfy the separable Teukolsky master equation (TME). For each of these spin s components defined in Kinnersley tetrad, the resulting equations by performing some first-order differential operator on it once and twice (twice only for s=±2), together with the TME, are in the form of an "inhomogeneous spin-weighted wave equation" (ISWWE) with different potentials and constitute a linear spin-weighted wave system. We then prove energy and integrated local energy decay (Morawetz) estimates for this type of ISWWE, and utilize them to achieve both a uniform bound of a positive definite energy and a Morawetz estimate for the regular extreme Newman-Penrose components defined in the regular Hawking-Hartle tetrad. We also present some brief discussions on mode stability for TME for the case of real frequencies. This says that in a fixed subextremal Kerr spacetime, there is no nontrivial separated mode solutions to TME which are purely ingoing at horizon and purely outgoing at infinity. This yields a representation formula for solutions to inhomogeneous Teukolsky equations, and will play a crucial role in generalizing the above energy and Morawetz estimates results to the full subextremal Kerr case.}, language = {en} } @phdthesis{Kegeles2018, author = {Kegeles, Alexander}, title = {Algebraic foundation of Group Field Theory}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-421014}, school = {Universit{\"a}t Potsdam}, pages = {124}, year = {2018}, abstract = {In this thesis we provide a construction of the operator framework starting from the functional formulation of group field theory (GFT). We define operator algebras on Hilbert spaces whose expectation values in specific states provide correlation functions of the functional formulation. Our construction allows us to give a direct relation between the ingredients of the functional GFT and its operator formulation in a perturbative regime. Using this construction we provide an example of GFT states that can not be formulated as states in a Fock space and lead to math- ematically inequivalent representations of the operator algebra. We show that such inequivalent representations can be grouped together by their symmetry properties and sometimes break the left translation symmetry of the GFT action. We interpret these groups of inequivalent representations as phases of GFT, similar to the classification of phases that we use in QFT's on space-time.}, language = {en} } @phdthesis{Gidion2018, author = {Gidion, Gunnar}, title = {Akustische Resonatoren zur Analyse und Kontrolle von schwingungsf{\"a}higen Systemen am Beispiel von Streichinstrumenten und Dielektrischen Elastomeraktoren}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-411772}, school = {Universit{\"a}t Potsdam}, pages = {190}, year = {2018}, abstract = {Die Klangeigenschaften von Musikinstrumenten werden durch das Zusammenwirken der auf ihnen anregbaren akustischen Schwingungsmoden bestimmt, welche sich wiederum aus der geometrischen Struktur des Resonators in Kombination mit den verwendeten Materialien ergeben. In dieser Arbeit wurde das Schwingungsverhalten von Streichinstrumenten durch den Einsatz minimal-invasiver piezoelektrischer Polymerfilmsensoren untersucht. Die studierten Kopplungsph{\"a}nomene umfassen den sogenannten Wolfton und Schwingungstilger, die zu dessen Abschw{\"a}chung verwendet werden, sowie die gegenseitige Beeinflussung von Bogen und Instrument beim Spielvorgang. An Dielektrischen Elastomeraktormembranen wurde dagegen der Einfluss der elastischen Eigenschaften des Membranmaterials auf das akustische und elektromechanische Schwingungsverhalten gezeigt. Die Dissertation gliedert sich in drei Teile, deren wesentliche Ergebnisse im Folgenden zusammengefasst werden. In Teil I wurde die Funktionsweise eines abstimmbaren Schwingungstilgers zur D{\"a}mpfung von Wolft{\"o}nen auf Streichinstrumenten untersucht. Durch Abstimmung der Resonanzfrequenz des Schwingungstilgers auf die Wolftonfrequenz kann ein Teil der Saitenschwingungen absorbiert werden, so dass die zu starke Anregung der Korpusresonanz vermieden wird, die den Wolfton verursacht. Der Schwingungstilger besteht aus einem „Wolft{\"o}ter", einem Massest{\"u}ck, welches auf der Nachl{\"a}nge der betroffenen Saite (zwischen Steg und Saitenhalter) installiert wird. Hier wurde gezeigt, wie die Resonanzen dieses Schwingungstilgers von der Masse des Wolft{\"o}ters und von dessen Position auf der Nachl{\"a}nge abh{\"a}ngen. Aber auch die Geometrie des Wolft{\"o}ters stellte sich als ausschlaggebend heraus, insbesondere bei einem nicht-rotationssymmetrischen Wolft{\"o}ter: In diesem Fall entsteht - basierend auf den zu erwartenden nicht-harmonischen Moden einer massebelasteten Saite - eine zus{\"a}tzliche Mode, die von der Polarisationsrichtung der Saitenschwingung abh{\"a}ngt. Teil II der Dissertation befasst sich mit Elastomermembranen, die als Basis von Dielektrischen Elastomeraktoren dienen, und die wegen der Membranspannung auch akustische Resonanzen aufweisen. Die Ansprache von Elastomeraktoren h{\"a}ngt unter anderem von der Geschwindigkeit der elektrischen Anregung ab. Die damit zusammenh{\"a}ngenden viskoelastischen Eigenschaften der hier verwendeten Elastomere, Silikon und Acrylat, wurden einerseits in einer frequenzabh{\"a}ngigen dynamisch-mechanischen Analyse des Elastomers erfasst, andererseits auch optisch an vollst{\"a}ndigen Aktoren selbst gemessen. Die h{\"o}here Viskosit{\"a}t des Acrylats, das bei tieferen Frequenzen h{\"o}here Aktuationsdehnungen als das Silikon zeigt, f{\"u}hrt zu einer Verminderung der Dehnungen bei h{\"o}heren Frequenzen, so dass {\"u}ber etwa 40 Hertz mit Silikon gr{\"o}ßere Aktuationsdehnungen erreicht werden. Mit den untersuchten Aktoren konnte die Gitterkonstante weicher optischer Beugungsgitter kontrolliert werden, die als zus{\"a}tzlicher Film auf der Membran installiert wurden. {\"U}ber eine Messung der akustischen Resonanzfrequenz von Elastomermebranen aus Acrylat in 1Abh{\"a}ngigkeit von ihrer Vorstreckung konnte in Verbindung mit einer Modellierung des hyperelastischen Verhaltens des Elastomers (Ogden-Modell) der Schermodul bestimmt werden. Schließlich wird in Teil III die Untersuchung von Geigen und ihrer Streichanregung mit Hilfe minimal-invasiver piezoelektrischer Polymerfilme geschildert. Es konnten am Bogen und am Steg von Geigen - unter den beiden F{\"u}ßen des Stegs - jeweils zwei Filmsensoren installiert werden. Mit den beiden Sensoren am Steg wurden Frequenzg{\"a}nge von Geigen gemessen, welche eine Bestimmung der frequenzabh{\"a}ngigen Stegbewegung erlaubten. Diese Methode erm{\"o}glicht damit auch eine umfassende Charakterisierung der Signaturmoden in Bezug auf die Stegdynamik. Die Ergebnisse der komplement{\"a}ren Methoden von Impulsanregung und nat{\"u}rlichem Spielen der Geigen konnten dank der Sensoren verglichen werden. F{\"u}r die Nutzung der Sensoren am Bogen - insbesondere f{\"u}r eine Messung des Bogendrucks - wurde eine Kalibrierung des Bogen-Sensor-Systems mit Hilfe einer Materialpr{\"u}fmaschine durchgef{\"u}hrt. Bei einer Messung w{\"a}hrend des nat{\"u}rlichen Spielens wurde mit den Sensoren am Bogen einerseits die {\"U}bertragung der Saitenschwingung auf den Bogen festgestellt. Dabei konnten außerdem longitudinale Bogenhaarresonanzen identifiziert werden, die von der Position der Saite auf dem Bogen abh{\"a}ngen. Aus der Analyse dieses Ph{\"a}nomens konnte die longitudinale Wellengeschwindigkeit der Bogenhaare bestimmt werden, die eine wichtige Gr{\"o}ße f{\"u}r die Kopplung zwischen Saite und Bogen ist. Mit Hilfe des Systems aus Sensoren an Bogen und Steg werden auf Grundlage der vorliegenden Arbeit Studien an Streichinstrumenten vorgeschlagen, in denen die Bespielbarkeit der Instrumente zu den jeweils angeregten Steg- und Bogenschwingungen in Beziehung gesetzt werden kann. Damit k{\"o}nnte nicht zuletzt auch die bisher nicht vollst{\"a}ndig gekl{\"a}rte Rolle des Bogens f{\"u}r Klang und Bespielbarkeit besser beurteilt werden}, language = {de} } @phdthesis{Buschmann2018, author = {Buschmann, Stefan}, title = {A software framework for GPU-based geo-temporal visualization techniques}, doi = {10.25932/publishup-44340}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-443406}, school = {Universit{\"a}t Potsdam}, pages = {viii, 99}, year = {2018}, abstract = {R{\"a}umlich-zeitliche Daten sind Daten, welche sowohl einen Raum- als auch einen Zeitbezug aufweisen. So k{\"o}nnen beispielsweise Zeitreihen von Geodaten, thematische Karten die sich {\"u}ber die Zeit ver{\"a}ndern, oder Bewegungsaufzeichnungen von sich bewegenden Objekten als r{\"a}umlich-zeitliche Daten aufgefasst werden. In der heutigen automatisierten Welt gibt es eine wachsende Anzahl von Datenquellen, die best{\"a}ndig r{\"a}umlich-zeitliche Daten generieren. Hierzu geh{\"o}ren beispielsweise Verkehrs{\"u}berwachungssysteme, die Bewegungsdaten von Menschen oder Fahrzeugen aufzeichnen, Fernerkundungssysteme, welche regelm{\"a}ßig unsere Umgebung scannen und digitale Abbilder wie z.B. Stadt- und Landschaftsmodelle erzeugen, sowie Sensornetzwerke in unterschiedlichsten Anwendungsgebieten, wie z.B. der Logistik, der Verhaltensforschung von Tieren, oder der Klimaforschung. Zur Analyse r{\"a}umlich-zeitlicher Daten werden neben der automatischen Analyse mittels statistischer Methoden und Data-Mining auch explorative Methoden angewendet, welche auf der interaktiven Visualisierung der Daten beruhen. Diese Methode der Analyse basiert darauf, dass Anwender in Form interaktiver Visualisierung die Daten explorieren k{\"o}nnen, wodurch die menschliche Wahrnehmung sowie das Wissen der User genutzt werden, um Muster zu erkennen und dadurch einen Einblick in die Daten zu erlangen. Diese Arbeit beschreibt ein Software-Framework f{\"u}r die Visualisierung r{\"a}umlich-zeitlicher Daten, welches GPU-basierte Techniken beinhaltet, um eine interaktive Visualisierung und Exploration großer r{\"a}umlich-zeitlicher Datens{\"a}tze zu erm{\"o}glichen. Die entwickelten Techniken umfassen Datenhaltung, Prozessierung und Rendering und erm{\"o}glichen es, große Datenmengen in Echtzeit zu prozessieren und zu visualisieren. Die Hauptbeitr{\"a}ge der Arbeit umfassen: - Konzept und Implementierung einer GPU-zentrierten Visualisierungspipeline. Die beschriebenen Techniken basieren auf dem Konzept einer GPU-zentrierten Visualisierungspipeline, in welcher alle Stufen -- Prozessierung,Mapping, Rendering -- auf der GPU ausgef{\"u}hrt werden. Bei diesem Konzept werden die r{\"a}umlich-zeitlichen Daten direkt im GPU-Speicher abgelegt. W{\"a}hrend des Rendering-Prozesses werden dann mittels Shader-Programmen die Daten prozessiert, gefiltert, ein Mapping auf visuelle Attribute vorgenommen, und schließlich die Geometrien f{\"u}r die Visualisierung erzeugt. Datenprozessierung, Filtering und Mapping k{\"o}nnen daher in Echtzeit ausgef{\"u}hrt werden. Dies erm{\"o}glicht es Usern, die Mapping-Parameter sowie den gesamten Visualisierungsprozess interaktiv zu steuern und zu kontrollieren. - Interaktive Visualisierung attributierter 3D-Trajektorien. Es wurde eine Visualisierungsmethode f{\"u}r die interaktive Exploration einer großen Anzahl von 3D Bewegungstrajektorien entwickelt. Die Trajektorien werden dabei innerhalb einer virtuellen geographischen Umgebung in Form von einfachen Geometrien, wie Linien, B{\"a}ndern, Kugeln oder R{\"o}hren dargestellt. Durch interaktives Mapping k{\"o}nnen Attributwerte der Trajektorien oder einzelner Messpunkte auf visuelle Eigenschaften abgebildet werden. Hierzu stehen Form, H{\"o}he, Gr{\"o}ße, Farbe, Textur, sowie Animation zur Verf{\"u}gung. Mithilfe dieses dynamischen Mappings wurden außerdem verschiedene Visualisierungsmethoden implementiert, wie z.B. eine Focus+Context-Visualisierung von Trajektorien mithilfe von interaktiven Dichtekarten, sowie einer Space-Time-Cube-Visualisierung zur Darstellung des zeitlichen Ablaufs einzelner Bewegungen. - Interaktive Visualisierung geographischer Netzwerke. Es wurde eine Visualisierungsmethode zur interaktiven Exploration geo-referenzierter Netzwerke entwickelt, welche die Visualisierung von Netzwerken mit einer großen Anzahl von Knoten und Kanten erm{\"o}glicht. Um die Analyse von Netzwerken verschiedener Gr{\"o}ßen und in unterschiedlichen Kontexten zu erm{\"o}glichen, stehen mehrere virtuelle geographische Umgebungen zur Verf{\"u}gung, wie bspw. ein virtueller 3D-Globus, als auch 2D-Karten mit unterschiedlichen geographischen Projektionen. Zur interaktiven Analyse dieser Netzwerke stehen interaktive Tools wie Filterung, Mapping und Selektion zur Verf{\"u}gung. Des weiteren wurden Visualisierungsmethoden f{\"u}r verschiedene Arten von Netzwerken, wie z.B. 3D-Netzwerke und zeitlich ver{\"a}nderliche Netzwerke, implementiert. Zur Demonstration des Konzeptes wurden interaktive Tools f{\"u}r zwei unterschiedliche Anwendungsf{\"a}lle entwickelt. Das erste beinhaltet die Visualisierung attributierter 3D-Trajektorien, welche die Bewegungen von Flugzeugen um einen Flughafen beschreiben. Es erm{\"o}glicht Nutzern, die Trajektorien von ankommenden und startenden Flugzeugen {\"u}ber den Zeitraum eines Monats interaktiv zu explorieren und zu analysieren. Durch Verwendung der interaktiven Visualisierungsmethoden f{\"u}r 3D-Trajektorien und interaktiven Dichtekarten k{\"o}nnen Einblicke in die Daten gewonnen werden, wie beispielsweise h{\"a}ufig genutzte Flugkorridore, typische sowie untypische Bewegungsmuster, oder ungew{\"o}hnliche Vorkommnisse wie Fehlanfl{\"u}ge. Der zweite Anwendungsfall beinhaltet die Visualisierung von Klimanetzwerken, welche geographischen Netzwerken in der Klimaforschung darstellen. Klimanetzwerke repr{\"a}sentieren die Dynamiken im Klimasystem durch eine Netzwerkstruktur, die die statistische Beziehungen zwischen Orten beschreiben. Das entwickelte Tool erm{\"o}glicht es Analysten, diese großen Netzwerke interaktiv zu explorieren und dadurch die Struktur des Netzwerks zu analysieren und mit den geographischen Daten in Beziehung zu setzen. Interaktive Filterung und Selektion erm{\"o}glichen es, Muster in den Daten zu identifizieren, und so bspw. Cluster in der Netzwerkstruktur oder Str{\"o}mungsmuster zu erkennen.}, language = {en} } @phdthesis{VillatoroLeal2018, author = {Villatoro Leal, Jos{\´e} Andr{\´e}s}, title = {A combined approach for the analysis of biomolecules using IR-MALDI ion mobility spectrometry and molecular dynamics simulations of peptide ions in the gas phase}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-419723}, school = {Universit{\"a}t Potsdam}, pages = {133}, year = {2018}, abstract = {The aim of this doctoral thesis was to establish a technique for the analysis of biomolecules with infrared matrix-assisted laser dispersion (IR-MALDI) ion mobility (IM) spectrometry. The main components of the work were the characterization of the IR-MALDI process, the development and characterization of different ion mobility spectrometers, the use of IR-MALDI-IM spectrometry as a robust, standalone spectrometer and the development of a collision cross-section estimation approach for peptides based on molecular dynamics and thermodynamic reweighting. First, the IR-MALDI source was studied with atmospheric pressure ion mobility spectrometry and shadowgraphy. It consisted of a metal capillary, at the tip of which a self-renewing droplet of analyte solution was met by an IR laser beam. A relationship between peak shape, ion desolvation, diffusion and extraction pulse delay time (pulse delay) was established. First order desolvation kinetics were observed and related to peak broadening by diffusion, both influenced by the pulse delay. The transport mechanisms in IR-MALDI were then studied by relating different laser impact positions on the droplet surface to the corresponding ion mobility spectra. Two different transport mechanisms were determined: phase explosion due to the laser pulse and electrical transport due to delayed ion extraction. The velocity of the ions stemming from the phase explosion was then measured by ion mobility and shadowgraphy at different time scales and distances from the source capillary, showing an initially very high but rapidly decaying velocity. Finally, the anatomy of the dispersion plume was observed in detail with shadowgraphy and general conclusions over the process were drawn. Understanding the IR-MALDI process enabled the optimization of the different IM spectrometers at atmospheric and reduced pressure (AP and RP, respectively). At reduced pressure, both an AP and an RP IR-MALDI source were used. The influence of the pulsed ion extraction parameters (pulse delay, width and amplitude) on peak shape, resolution and area was systematically studied in both AP and RP IM spectrometers and discussed in the context of the IR-MALDI process. Under RP conditions, the influence of the closing field and of the pressure was also examined for both AP and RP sources. For the AP ionization RP IM spectrometer, the influence of the inlet field (IF) in the source region was also examined. All of these studies led to the determination of the optimal analytical parameters as well as to a better understanding of the initial ion cloud anatomy. The analytical performance of the spectrometer was then studied. Limits of detection (LOD) and linear ranges were determined under static and pulsed ion injection conditions and interpreted in the context of the IR-MALDI mechanism. Applications in the separation of simple mixtures were also illustrated, demonstrating good isomer separation capabilities and the advantages of singly charged peaks. The possibility to couple high performance liquid chromatography (HPLC) to IR-MALDI-IM spectrometry was also demonstrated. Finally, the reduced pressure spectrometer was used to study the effect of high reduced field strength on the mobility of polyatomic ions in polyatomic gases. The last focus point was on the study of peptide ions. A dataset obtained with electrospray IM spectrometry was characterized and used for the calibration of a collision cross-section (CCS) determination method based on molecular dynamics (MD) simulations at high temperature. Instead of producing candidate structures which are evaluated one by one, this semi-automated method uses the simulation as a whole to determine a single average collision cross-section value by reweighting the CCS of a few representative structures. The method was compared to the intrinsic size parameter (ISP) method and to experimental results. Additional MD data obtained from the simulations was also used to further analyze the peptides and understand the experimental results, an advantage with regard to the ISP method. Finally, the CCS of peptide ions analyzed by IR-MALDI were also evaluated with both ISP and MD methods and the results compared to experiment, resulting in a first validation of the MD method. Thus, this thesis brings together the soft ionization technique that is IR-MALDI, which produces mostly singly charged peaks, with ion mobility spectrometry, which can distinguish between isomers, and a collision cross-section determination method which also provides structural information on the analyte at hand.}, language = {en} } @phdthesis{Engelhardt2018, author = {Engelhardt, Jonathan}, title = {40Ar/39Ar geochronology of ICDP PALEOVAN drilling cores}, doi = {10.25932/publishup-42953}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-429539}, school = {Universit{\"a}t Potsdam}, pages = {xxi, 338}, year = {2018}, abstract = {The scientific drilling campaign PALEOVAN was conducted in the summer of 2010 and was part of the international continental drilling programme (ICDP). The main goal of the campaign was the recovery of a sensitive climate archive in the East of Anatolia. Lacustrine deposits underneath the lake floor of 'Lake Van' constitute this archive. The drilled core material was recovered from two locations: the Ahlat Ridge and the Northern Basin. A composite core was constructed from cored material of seven parallel boreholes at the Ahlat Ridge and covers an almost complete lacustrine history of Lake Van. The composite record offered sensitive climate proxies such as variations of total organic carbon, K/Ca ratios, or a relative abundance of arboreal pollen. These proxies revealed patterns that are similar to climate proxy variations from Greenland ice cores. Climate variations in Greenland ice cores have been dated by modelling the timing of orbital forces to affect the climate. Volatiles from melted ice aliquots are often taken as high-resolution proxies and provide a base for fitting the according temporal models. The ICDP PALEOVAN scientific team fitted proxy data from the lacustrine drilling record to ice core data and constructed an age model. Embedded volcaniclastic layers had to be dated radiometrically in order to provide independent age constraints to the climate-stratigraphic age model. Solving this task by an application of the 40Ar/39Ar method was the main objective of this thesis. Earlier efforts to apply the 40Ar/39Ar dating resulted in inaccuracies that could not be explained satisfactorily. The absence of K-rich feldspars in suitable tephra layers implied that feldspar crystals needed to be 500 μm in size minimum, in order to apply single-crystal 40Ar/39Ar dating. Some of the samples did not contain any of these grain sizes or only very few crystals of that size. In order to overcome this problem this study applied a combined single-crystal and multi-crystal approach with different crystal fractions from the same sample. The preferred method of a stepwise heating analysis of an aliquot of feldspar crystals has been applied to three samples. The Na-rich crystals and their young geological age required 20 mg of inclusion-free, non-corroded feldspars. Small sample volumes (usually 25 \% aliquots of 5 cm3 of sample material - a spoon full of tephra) and the widespread presence of melt-inclusion led to the application of combined single- and multigrain total fusion analyses. 40Ar/39Ar analyses on single crystals have the advantage of being able to monitor the presence of excess 40Ar and detrital or xenocrystic contamination in the samples. Multigrain analyses may hide the effects from these obstacles. The results from the multigrain analyses are therefore discussed with respect to the findings from the respective cogenetic single crystal ages. Some of the samples in this study were dated by 40Ar/39Ar on feldspars on multigrain separates and (if available) in combination with only a few single crystals. 40Ar/39Ar ages from two of the samples deviated statistically from the age model. All other samples resulted in identical ages. The deviations displayed older ages than those obtained from the age model. t-Tests compared radiometric ages with available age control points from various proxies and from the relative paleointensity of the earth magnetic field within a stratigraphic range of ± 10 m. Concordant age control points from different relative chronometers indicated that deviations are a result of erroneous 40Ar/39Ar ages. The thesis argues two potential reasons for these ages: (1) the irregular appearance of 40Ar from rare melt- and fluid- inclusions and (2) the contamination of the samples with older crystals due to a rapid combination of assimilation and ejection. Another aliquot of feldspar crystals that underwent separation for the application of 40Ar/39Ar dating was investigated for geochemical inhomogeneities. Magmatic zoning is ubiquitous in the volcaniclastic feldspar crystals. Four different types of magmatic zoning were detected. The zoning types are compositional zoning (C-type zoning), pseudo-oscillatory zoning of trace ele- ment concentrations (PO-type zoning), chaotic and patchy zoning of major and trace element concentrations (R-type zoning) and concentric zoning of trace elements (CC-type zoning). Sam- ples that deviated in 40Ar/39Ar ages showed C-type zoning, R-type zoning or a mix of different types of zoning (C-type and PO-type). Feldspars showing PO-type zoning typically represent the smallest grain size fractions in the samples. The constant major element compositions of these crystals are interpreted to represent the latest stages in the compositional evolution of feldspars in a peralkaline melt. PO-type crystals contain less melt- inclusions than other zoning types and are rarely corroded. This thesis concludes that feldspars that show PO-type zoning are most promising chronometers for the 40Ar/39Ar method, if samples provide mixed zoning types of Quaternary anorthoclase feldspars. Five samples were dated by applying the 40Ar/39Ar method to volcanic glass. High fractions of atmospheric Ar (typically > 98\%) significantly hampered the precision of the 40Ar/39Ar ages and resulted in rough age estimates that widely overlap the age model. Ar isotopes indicated that the glasses bore a chorine-rich Ar-end member. The chlorine-derived 38Ar indicated chlorine-rich fluid-inclusions or the hydration of the volcanic glass shards. This indication strengthened the evidence that irregularly distributed melt-inclusions and thus irregular distributed excess 40Ar influenced the problematic feldspar 40Ar/39Ar ages. Whether a connection between a corrected initial 40Ar/36Ar ratio from glasses to the 40Ar/36Ar ratios from pore waters exists remains unclear. This thesis offers another age model, which is similarly based on the interpolation of the temporal tie points from geophysical and climate-stratigraphic data. The model used a PCHIP- interpolation (piecewise cubic hermite interpolating polynomial) whereas the older age model used a spline-interpolation. Samples that match in ages from 40Ar/39Ar dating of feldspars with the earlier published age model were additionally assigned with an age from the PCHIP- interpolation. These modelled ages allowed a recalculation of the Alder Creek sanidine mineral standard. The climate-stratigraphic calibration of an 40Ar/39Ar mineral standard proved that the age versus depth interpolations from PAELOVAN drilling cores were accurate, and that the applied chronometers recorded the temporal evolution of Lake Van synchronously. Petrochemical discrimination of the sampled volcaniclastic material is also given in this thesis. 41 from 57 sampled volcaniclastic layers indicate Nemrut as their provenance. Criteria that served for the provenance assignment are provided and reviewed critically. Detailed correlations of selected PALEOVAN volcaniclastics to onshore samples that were described in detail by earlier studies are also discussed. The sampled volcaniclastics dominantly have a thickness of < 40 cm and have been ejected by small to medium sized eruptions. Onshore deposits from these types of eruptions are potentially eroded due to predominant strong winds on Nemrut and S{\"u}phan slopes. An exact correlation with the data presented here is therefore equivocal or not possible at all. Deviating feldspar 40Ar/39Ar ages can possibly be explained by inherited 40Ar from feldspar xenocrysts contaminating the samples. In order to test this hypothesis diffusion couples of Ba were investigated in compositionally zoned feldspar crystals. The diffusive behaviour of Ba in feldspar is known, and gradients in the changing concentrations allowed for the calculation of the duration of the crystal's magmatic development since the formation of the zoning interface. Durations were compared with degassing scenarios that model the Ar-loss during assimilation and subsequent ejection of the xenocrystals. Diffusive equilibration of the contrasting Ba concentrations is assumed to generate maximum durations as the gradient could have been developed in several growth and heating stages. The modelling does not show any indication of an involvement of inherited 40Ar in any of the deviating samples. However, the analytical set-up represents the lower limit of the required spatial resolution. Therefore, it cannot be excluded that the degassing modelling relies on a significant overestimation of the maximum duration of the magmatic history. Nevertheless, the modelling of xenocrystal degassing evidences that the irregular incorporation of excess 40Ar by melt- and fluid inclusions represents the most critical problem that needs to be overcome in dating volcaniclastic feldspars from the PALEOVAN drill cores. This thesis provides the complete background in generating and presenting 40Ar/39Ar ages that are compared to age data from a climate-stratigraphic model. Deviations are identified statistically and then discussed in order to find explanations from the age model and/or from 40Ar/39Ar geochronology. Most of the PALEOVAN stratigraphy provides several chronometers that have been proven for their synchronicity. Lacustrine deposits from Lake Van represent a key archive for reconstructing climate evolution in the eastern Mediterranean and in the Near East. The PALEOVAN record offers a climate-stratigraphic age model with a remarkable accuracy and resolution.}, language = {en} }