The Earth mantle convects on a global scale, coupling the stress field at every point to every other location at an instant. This way, any change in the buoyancy field has an immediate impact on the convection patterns worldwide. At the same time, mantle convection couples to processes at scales of a few kilometers or even a few hundred meters. Dynamic topography and the geoid are examples of such small-scale expressions of mantle convection. Also, the depth of phase transitions varies locally, with strong influences on the buoyancy, and thus the global stress field. In order to understand these processes dynamically it is essential to resolve the whole mantle at very high numerical resolutions. At the same time, geodynamicists are trying to answer new questions with their models, for example about the rheology of the mantle, which is most likely highly nonlinear. Also, due to the extremely long timescales we cannot observe past mantle states, which calls for simulations backwards in time. All these issues lead to an extreme demand in computing power. To cater to those needs, the physical models of the mantle have to be matched with efficient solvers and fast algorithms, such that we can efficiently exploit the enormous computing power of current and future high performance systems. Here, we first give an extensive overview over the physical models and introduce some numerical concepts to solve the equations. We present a new two-dimensional software as a testbed and elaborate on the implications of realistic mineralogic models for efficient mantle convection simulations. We find that phase transitions present a major challenge and suggest some procedures to incorporate them into mantle convection modeling. Then we give an introduction to the high-performance mantle convection prototype HHG, a multigrid-based software framework that scales to some of the fastest computers currently available. We adapt this framework to a spherical geometry and present first application examples to answer geodynamic questions. In particular, we show that a very thin and very weak asthenosphere is dynamically plausible and consistent with direct and indirect geological observations.

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Feb 08, 2016

The mitochondria of non-bilaterian metazoans display a staggering diversity of genome organizations and also a slow rate of mtDNA evolution, unlike bilaterians, which may hold a key to understand the early evolution of the animal mitochondrion. Octocorals are unique members of Phylum Cnidaria, harboring several atypical mitochondrial genomic features, including a paucity of tRNA genes, various genome arrangements and the presence of novel putative mismatch repair gene (mtMutS) with various potential biological roles. Thus octocorals represents an interesting model for the study of mitochondrial biology and evolution. However, besides its utility in molecular phylogenetics, the mtDNA of octocorals is not studied from the perspective of DNA repair, oxidative stress response or gene expression; and there is a general lack of knowledge on the DNA repair capabilities and role of the mtMutS gene, response to climate-change, and mtDNA transcription in absence of interspersed tRNA genes of octocoral mitochondrial genome. In order to put the observed novelties in the octocoral mitochondria in an evolutionary and an environmental context, and to understand their potential functions and the consequences of their presence in conferring fitness during climate change induced stress, this study was undertaken. This dissertation aims to explore the uniqueness and diversity of octocoral mtDNA from an environmental as well as an evolutionary perspective. The thesis comprises five chapters exploring various facets of octocoral biology. The introductory section provides basic information and elaborates on the importance of studying non-bilaterian mitochondria. The first chapter sets the base for subsequent gene expression studies. Octocorals are extensively studied from a taxonomic and phylogenetic point of view. However, gene expression studies on these organisms have only recently started to appear. To successfully employ the most commonly used gene expression profiling technique i.e., the quantitation real-time PCR (qPCR), it is necessary to have an experimentally validated, treatment-specific set of stably expressed reference genes that will support for the accurate quantification of changes in expression of genes of interest. Hence, seven housekeeping genes, known to exhibit constitutive expression, were investigated for expression stability during simulated climate-changed (i.e. thermal and low-pH) induced stress. These genes were validated and subsequently used in gene expression studies on Sinularia cf. cruciata, our model octocoral. The occurrence of a mismatch repair gene, and the slow rates of mtDNA evolution in octocoral mitogenome calls for further investigations on the potential robustness of octocoral mitochondria to the increased oxidative stress. The second chapter presents a mitochondrion-centric view of climate-change stress response by investigating mtDNA damage, repair, and copy number dynamics during stress. The changes in gene expression of a set of stress-related nuclear, and mitochondrial genes in octocorals were also monitored. A robust response of octocoral mitochondria to oxidative mtDNA damage was observed, exhibiting a rapid recovery of the damaged mtDNA. The stress-specific regulation of the mtMutS gene was detected, indicating its potential involvement in stress response. The results highlight the resilience potential of octocoral mitochondria, and its adaptive benefits in changing oceans. The tRNA genes in animal mitochondria play a pivotal role in mt-mRNA processing and maturation. The influence of paucity of tRNA genes on transcription of the mitogenome in octocorals has not been investigated. The third chapter steps in the direction to understand the mitogenome transcription by investigating the nature of mature mRNAs. Several novel features not present in a “typical” animal mt-mRNAs were detected. The majority of the mitochondrial transcripts were observed as polycistronic units (i.e. the mRNA carrying information for the synthesis of more than one protein). 5’ and 3’ untranslated regions were delineated for most protein-coding genes. Alternative polyadenylation (APA) of mtMutS gene and long non-coding RNA (lncRNA) for ATP6 were detected and are reported for the first time in non-bilaterian metazoans providing a glimpse into the complexity and uniqueness of mtDNA transcription in octocorals. The mismatch repair (MMR) mechanism plays a crucial role in mutation avoidance and maintenance of genomic integrity. Its occurrence in animal mitochondria remains equivocal. Octocorals are the only known animals to posses an mtDNA-encoded MMR gene, the mtMutS, speculated to have self-contained DNA repair capability. In order to gain knowledge of the MMR activity in the octocoral mitochondria MMR assays using the octocoral mitochondrial fraction is necessary. A prerequisite for this assay is the availability of an MMR-substrate, which is a DNA fragment, usually a plasmid, containing the desired mismatch lesion (i.e. a heteroduplex) and a nicked strand. However, the methods to prepare such a substrate are time consuming and technically demanding. Chapter four describes two convenient and flexible strategies that can be used in parallel to prepare heteroduplex MMR substrate using a common plasmid and routine molecular biology techniques. This method should aid in MMR investigations in general, helping to advance this field of research. The mtMutS gene mentioned above is a bacterial homolog, predicted to have been horizontally transferred to the octocoral mitogenome. However, unlike the bacterial mutS, which is extensively studied, protein expression studies of the octocoral mtMutS gene are lacking. To investigate the biological role of the mtMutS protein, in vitro, and to gain knowledge on its structure and function, the expression of the gene in a bacterial host is necessary. The fifth chapter discusses the characteristics of the mtMutS protein, the efforts to express it in E. coli and some necessary precautions to be taken while working with the expression of such mtDNA-encoded proteins for the research in future. This dissertation elucidates and contributes to the understanding of the unexplored complexity of non-bilaterian mitochondria. It deals for the first time with DNA repair, gene expression and gene function, encompassing an integrative analysis of DNA, RNA and proteins to achieve its goals. This study forms the basis for many future investigations on the molecular mitochondrial biology of octocorals as well as other non-bilaterians, augmenting the understanding of the evolution of animal mitochondria, and also its role in cellular and organismal homeostasis in the context of environmental change.

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Dec 21, 2015

Someday in 2007, the world population reached a historical landmark: for the first time in human history, more than half of the world´s population was urban. A stagnation of this urbanization process is not in sight, so that by 2050, already 70 percent of humankind is projected to live in urban settlements. Over the last few decades, enormous migrations from rural hinterlands to steadily growing cities could be witnessed coming along with a dramatic growth of the world’s urban population. The speed and the scale of this growth, particularly in the so called less developed regions, are posing tremendous challenges to the countries concerned as well as to the world community. Within mega cities the strongest trends and the most extreme dimensions of the urbanization process can be observed. Their rapid growth results in uncontrolled processes of fragmentation which is often associated with pronounced poverty, social inequality, socio-spatial and political fragmentation, environmental degradation as well as population demands that outstrip environmental service capacity. For the majority of the mega cities a tremendous increase of informal structures and processes has to be observed. Consequentially informal settlements are growing, which represent those characteristic municipal areas being subject to particularly high population density, dynamics as well as marginalization. They have quickly become the most visible expression of urban poverty in developing world cities. Due to the extreme dynamics, the high complexity and huge spatial dimension of mega cities, urban administrations often only have an obsolete or not even existing data basis available to be at all informed about developments, trends and dimensions of urban growth and change. The knowledge about the living conditions of the residents is correspondingly very limited, incomplete and not up to date. Traditional methods such as statistical and regional analyses or fieldwork are no longer capable to capture such urban process. New data sources and monitoring methodologies are required in order to provide an up to date information basis as well as planning strate¬gies to enable sustainable developments and to simplify planning processes in complex urban structures. This research shall seize the described problem and aims to make a contribution to the requirements of monitoring fast developing mega cities. Against this background a methodology is developed to compensate the lack of socio-economic data and to deduce meaningful information on the living conditions of the inhabitants of mega cities. Neither social science methods alone nor the exclusive analysis of remote sensing data can solve the problem of the poor quality and outdated data base. Conventional social science methods cannot cope with the enormous developments and the tremendous growth as they are too labor-, as well as too time- and too cost-intensive. On the other hand, the physical discipline of remote sensing does not allow for direct conclusions on social parameters out of remote sensing images. The prime objective of this research is therefore the development of an integrative approach − bridging remote sensing and social analysis – in order to derive useful information about the living conditions in this specific case of the mega city Delhi and its inhabitants. Hence, this work is established in the overlapping range of the research topics remote sensing, urban areas and social science. Delhi, as India’s fast growing capital, meanwhile with almost 25 million residents the second largest city of the world, represents a prime example of a mega city. Since the second half of the 20th century, Delhi has been transformed from a modest town with mainly administrative and trade-related functions to a complex metropolis with a steep socio-economic gradient. The quality and amount of administrative and socio-economic data are poor and the knowledge about the circumstances of Delhi’s residents is correspondingly insufficient and outdated. Delhi represents therefore a perfectly suited study area for this research. In order to gather information about the living conditions within the different settlement types a methodology was developed and conducted to analyze the urban environment of the mega city Delhi. To identify different settlement types within the urban area, regarding the complex and heterogeneous appearance of the Delhi area, a semi-automated, object-oriented classification approach, based on segmentation derived image objects, was implemented. As the complete conceptual framework of this research, the classification methodology was developed based on a smaller representative training area at first and applied to larger test sites within Delhi afterwards. The object-oriented classification of VHR satellite imagery of the QuickBird sensor allowed for the identification of five different urban land cover classes within the municipal area of Delhi. In the focus of the image analysis is yet the identification of different settlement types and amongst these of informal settlements in particular. The results presented within this study demonstrate, that, based on density classes, the developed methodology is suitable to identify different settlement types and to detect informal settlements which are mega urban risk areas and thus potential residential zones of vulnerable population groups. The remote sensing derived land cover maps form the foundation for the integrative analysis concept and deliver there¬fore the general basis for the derivation of social attributes out of remote sensing data. For this purpose settlement characteristics (e.g., area of the settlement, average building size, and number of houses) are estimated from the classified QuickBird data and used to derive spatial information about the population distribution. In a next step, the derived information is combined with in-situ information on socio-economic conditions (e.g., family size, mean water consumption per capita/family) extracted from georeferenced questionnaires conducted during two field trips in Delhi. This combined data is used to characterize a given settlement type in terms of specific population and water related variables (e.g., population density, total water consumption). With this integrative methodology a catalogue can be compiled, comprising the living conditions of Delhi’s inhabitants living in specific settlement structures – and this in a quick, large-scaled, cost effective, by random or regularly repeatable way with a relatively small required data basis.The combined application of remotely sensed imagery and socio-economic data allows for the mapping, capturing and characterizing the socio-economic structures and dynamics within the mega city of Delhi, as well as it establishes a basis for the monitoring of the mega city of Delhi or certain areas within the city respectively by remote sensing. The opportunity to capture the condition of a mega city and to monitor its development in general enables the persons in charge to identify unbeneficial trends and to intervene accordingly from an urban planning perspective and to countersteer against a non-adequate supply of the inhabitants of different urban districts, primarily of those of informal settlements. This study is understood to be a first step to the development of methods which will help to identify and understand the different forms, actors and processes of urbanization in mega cities. It could support a more proactive and sustainable urban planning and land management – which in turn will increase the importance of urban remote sensing techniques. In this regard, the most obvious and direct beneficiaries are on the one hand the governmental agencies and urban planners and on the other hand, and which is possibly the most important goal, the inhabitants of the affected areas, whose living conditions can be monitored and improved as required. Only if the urban monitoring is quickly, inexpensively and easily available, it will be accepted and applied by the authorities, which in turn enables for the poorest to get the support they need. All in all, the listed benefits are very convincing and corroborate the combined use of remotely sensed and socio-economic data in mega city research.

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Nov 04, 2015

Sponges are simple animals that mostly inhabit the marine ecosystem. The role of sponges in the marine ecosystem and the potential of their bioactive compounds for the pharmaceutical industry have already been reviewed. Because of the extensive investigations of sponges within those two disciplines, marine ecology and chemistry, sponges are among the best-studied Metazoa. Likewise, sponges have been selected as animal models for investigating the origin of the multicellularity because sponges have a simple body structure and physiology (e.g., lack of nervous and circulatory organs). Due to their diversity and abundance in the tropics, particularly in the Indo-Pacific, sponges have also attracted taxonomists, systematists and ecologists to assess their diverseness and their phylogenetic and phylogeographic relationships. Resolving those research questions is difficult, because sponges are categorised as comparatively character poor taxa. By using only conservative taxonomy or systematics, the sponge diversity might therefore be underestimated. Inevitably, sponge biologists have to employ molecular methods as additional tools. In this research, molecular tools were used in order to analyse the taxonomy, phylogeny and phylogeographic relationships of selected sponge species. Xestospongia testudinaria & Neopetrosia exigua (Family Petrosiidae, Order Haplosclerida) were selected because of their conspicuousness in the Indo-Pacific coral reef ecosystems, whereby Xestospongia testudinaria is prominently known as the Indo-Pacific giant barrel sponge. Additionally, the order Haplosclerida has been described as an example of sponge order that has been examined systematically for a number of years and displays major discrepancy between morphology and molecular phylogenies. Molecular data suggests that the order needs revision at all taxonomic levels, which is the cause for further conflicts between taxonomists and systematists. In my research I focused mostly on sponge samples that originated from South East Asia or the Indo-Australian Archipelago (IAA). This region represents one of the best-explored marine regions in the Indo-Pacific. The aim of my research is to discover to what extent molecular tools are suitable to detect a phylogenetic signal, a phylogeographical break or a genotypic difference in the two selected sponge taxa. Several markers from the mitochondrial (mtDNA), ribosomal (rRNA) and nuclear (nucDNA) have been utilised. The 3' partition of the cytochrome oxidase subunit 1 (I3-M11 of cox1) from the mtDNA could be used to detect a genetic structure in Xestospongia testudinaria in a geographical narrow scale study of < 200 km2 in Lembeh, North Sulawesi, Indonesia (Chapter 6) and throughout the Indo-Pacific despite limitations in the sample datasets (Chapter 2). In addition, the presence of a species complex in X. testudinaria was detected with the aid of phylogenetic reconstructions from a concatenation of mtDNA sequences (I3-M11 of cox1 and the Adenosine Triphosphate Synthase F0 subunit 6 / ATP6), and a nucDNA marker, the Adenosine Triphosphate Synthase β subunit intron (ATPS-β intron) (Chapter 6). At the same time, the presence of a species complex in X. testudinaria was recognised in a broader scale study of the Indo-Australian Archipleago (IAA) (Chapter 3). As a result, selected mtDNA and nucDNA markers in this thesis are useful for the investigation of the taxonomical status and phylogeographical relationships of X. testudinaria. A phylogeographical break in the IAA region due to the Pleistocene low sea level and Holocene recolonisation events (Chapter 3) could not be recovered among X. testudinaria in a phylogeographical analysis. Similarly, overlapping I3-M11 cox1 haplotypes between X. testudinaria, X. muta and X. bergquistia were recovered. This might be due to the presence of ancient polymorphisms on the barrel sponge mtDNA markers. Molecular tools are also used to help identifying my second selected sponge species (Chapter 4). The use of selected cox2 mtDNA and 28S rRNA markers contributed significantly to the identification of. Neopetrosia exigua used to be a congeneric of X. testudinaria. During my examinations of self-collected and holotype specimens I discovered that the species named N. exigua bears a wrong name. For this reason, a taxonomical revision is suggested and, more importantly, according to my findings and the principle of priority in the ICZN (International Code of Zoological Nomenclature) I use the species name ‘chaliniformis’ instead of the species name ‘exigua’. Furthermore, the use of selected nucDNA marker, the Lysidyl Aminoacyl Transfer RNA Synthetase (LTRS) intron, also contributes to the detection of phylogeographical breaks in N. chaliniformis of the IAA (Chapter 5). In a nutshell, the success of unravelling sponge taxonomies, phylogenies, and phylogeographic relationships always depends on the suitability of the utilised molecular markers and the significance of environmental influences on the sponges. Haplosclerid sponges possess limited morphological features. These hurdles create several problems, e.g. difficulties with taxa delimitation and unresolved phylogeography relationships. Even though the application of molecular techniques generated some limitations and obstacles in these studies, it has already contributed significantly to a better understanding of the phylogenies, phylogeographic relationships and taxonomical problems of X. testudinaria and N.chaliniformis, the species I selected for my research.

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Oct 20, 2015

Explosive volcanism is one of the most catastrophic material failure phenomena. During magma ascent, fragmentation produces particulate magma, which, if deposited above the glass transition of the interstitial melt, will sinter viscously. In-conduit tuffisites, conduit wall breccias and ash deposited from exceptionally hot pyroclastic flows are scenarios in which sintering by viscous flow is possible. Therefore, understanding the kinetics of sintering and the characteristic timescales over which magma densifies are critical to understanding the degassing timeframe in conduits and deposits. Viscous sintering is accompanied by a recovery of material strength towards that of a pore-free, dense magma. Understanding damage mechanisms and seismic behaviour prior to failure of sintered volcanic products are also crucial for the application of micromechanical models and material failure forecasting laws. Powdered standard glass and industrial glass beads have been used to explore sintering mechanisms at ambient pressure conditions and temporal evolution of connected and isolated pore-structure. I observe that sintering under low axial stress is essentially particle size, surface tension and melt viscosity controlled. I found that the timescales over which the bulk density approaches that of a pore-free melt at a given temperature is dependent on the particle-contact surface area, which can be estimated from the particle shape, the packing type and the initial total porosity. Granulometric constraint on the starting material indicates that the fraction of finer particles controls the rate of sintering as they cluster in pore spaces between larger particles and have a higher driving force for sintering due to their higher surface energy to volume ratio. Consequently, the resultant sample suite has a range of microstructures because the viscous sintering process promotes a fining of pores and a coarsening of particles. In a volcano, newly formed sintering material will then further contribute to magma-plugging of the conduit and its mechanical properties will affect magma rupture and its associated precursory signals. This consideration permitted me to explore the effect of sintering on the stress required for dynamic macroscopic failure of synthesised samples and assess the ability of precursory microseismic signals to be used as a failure forecast proxy at conditions relevant to shallow volcanic conduits. To this end, the samples were subjected to mechanical tests under a constant rate of deformation and at a temperature in the region of the material glass transition. A dual acoustic emission rig was employed to track the occurrence of brittle fracturing. The monitored acoustic dataset was then exploited to systematically assess the accuracy of the failure forecasting method as a function of heterogeneity (cast as porosity) since it acts as nucleating site for fracture propagation. The pore-emanating crack model describes well the peak stress at failure in the elastic regime for these materials. I show that the failure forecast method predicts failure within 0-15% error at porosities >0.2. However, when porosities are 100%. I interpret these results as a function of the low efficiency with which strain energy can be released in the scenario where there are few or no heterogeneities from which cracks can propagate. These observations shed light on questions surrounding the variable efficacy of the failure forecast method applied to active volcanoes. In particular, they provide a systematic demonstration of the fact that a good understanding of material properties is required. Thus I wish to emphasise the need for a better coupling of empirical failure forecasting models with mechanical parameters, such as failure criteria for heterogeneous materials, and point to the implications of this for a broad range of material-based disciplines.

1s

Sep 23, 2015

This dissertation explores the effects of pressure on the magnetic remanence of iron-nickel and iron-silicon alloys relevant to the solid inner cores of the terrestrial planets and Earth’s moon. The Earth’s inner core likely comprises mostly pure iron in a hexagonal close packed (hcp) structure. Experiments on pure iron powder and foil were carried out up to 21 GPa at room temperature. The most important conclusion from this work is that either hcp-iron is ferromagnetic or that a poorly understood, intermediate hcp phase of iron is ferromagnetic. It was also determined that the results must be corrected for magnetic shape anisotropy, which is related either to the original sample material (foil) or how the bulk sample volume changes shape due to increasing oblateness of the chamber during pressurization. Fe-Ni alloys in the face centered cubic (fcc) phase with compositions around Fe64Ni36, called Invar, exhibit near-null thermal expansion, making them useful for technological applications. Models explaining the Invar effect evoke magnetovolume effect that compensate for thermal expansion. Previous work suggested that the Curie temperature of Fe64Ni36 decreases 35 K per GPa, which predicts that around 5 GPa, Fe64Ni36 will turn paramagnetic. Our experiments on Fe64Ni36 found a marked decrease in magnetization between 5-7 GPa, consistent with former studies, but that it remains ferromagnetic until 16 GPa. The magnetic remanence of low Ni Invar alloys increases faster with pressure than for other body-centered-cubic compositions due to the higher magnetostriction of the low Ni Invar metals. Experimental results on body centered cubic (bcc) Fe-Ni alloys match well with those for pure iron-- again leading to the conclusion that either an intermediate hcp phase, or that the hcp phase itself, is ferromagnetic. The ubiquitous enhancement in magnetization under pressure, or during pressure release, of the Fe-Ni and Fe-Si alloys is associated with strain-induced martensitic effects. Finally, a defocused laser heating technique was developed to measure the Curie temperature in diamond or moissanite anvil cells. Preliminary results on titanomagnetite (Fe2.4Ti0.6O4) are broadly consistent with previous work.

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Jul 17, 2015

Bereits zu Beginn des 20. Jahrhunderts entwickelte Alfred Wegener seine allgemein bekannte Rekonstruktion der Kontinente, indem er die Fragmente kontinentaler Kruste durch Schließung der großen Ozeane entlang ihrer heutigen Küstenlinien zusammenfügte, so dass alle Kontinente zu einer Landmasse vereint waren. Den resultierenden Superkontinent nannte er "Pangäa" (Wegener, 1920). In dieser Rekonstruktion liegen sich Nord- und Südamerika gegenüber und Nordwestafrika grenzt an die Südostküste Nordamerikas. Lange Zeit nahm man an, dass die Paläogeographie dieses Superkontinents sich im Laufe seiner Existenz nicht bedeutend verändert hat, sondern dass die Kontinente sich im Jura im Wesentlichen aus der gleichen Konfiguration heraus voneinander gelöst haben, zu der sie sich ursprünglich im Paläozoikum zusammengefunden hatten. In der Tat gibt es vielfältige geologische, paläontologische und geophysikalische Hinweise dafür, dass Wegeners Pangäa-Konfiguration von der späten Trias bis in den frühen Jura Bestand hatte. In den späten Fünfzigerjahren des vergangenen Jahrhunderts entwickelte sich mit der Paläomagnetik eine Methode, die es ermöglicht, die Bewegungen der Kontinente über das Alter des ältesten bekannten Ozeanbodens hinaus zu rekonstruieren. Aufgrund des Dipolcharakters des Erdmagnetfeldes gilt das jedoch nur für die Rekonstruktion von paläogeographischen Breitenlagen, die Lage bezüglich der Längengrade kann mit Hilfe des Erdmagnetfeldes nicht eindeutig bestimmt werden. Eine nicht unerhebliche Anzahl paläomagnetischer Studien hat gezeigt, dass Wegeners Pangäarekonstruktion, auch Pangäa A genannt, mit globalen paläomagnetischen Daten in prä-triassischer Zeit nicht kompatibel ist. Zwingt man die Nord- und Südkontinente Pangäas, Laurasia und Gondwana für diese Zeit in die Pangäa A Konfiguration, so ergibt die auf paläomagnetischen Daten basierende paläogeographische Rekonstruktion ein signifikantes Überlappen kontinentaler Krustenanteile (siehe z. B. Van der Voo (1993); Muttoni et al. (1996, 2003) und darin zitierte Werke). Ein solches Überlappen lässt sich jedoch mit grundlegenden geologischen Prinzipien nicht vereinen. Im Lauf der Jahrzehnte wurden vielfältige alternative prä-triassische paläogeographische Pangäarekonstruktionen erstellt, die im Einklang mit den paläomagnetischen Daten sind. Der Hauptunterschied im Vergleich dieser Rekonstruktionen zur klassischen Pangäa A Konfiguration liegt in der Lage der Südkontinente relativ zu den Nordkontinenten. Um den kontinentalen Überlapp zu vermeiden, werden die Südkontinente unter Beibehaltung ihrer Breitenlage um ca. 30 Längengrade relativ zu den Nordkontinenten weiter im Osten platziert, so dass Nordwestafrika gegenüber Europa zu liegen kommt (Pangäa B, Irving (1977)). Da - wie erwähnt - der Dipolcharakter des Erdmagnetfeldes keine Aussagen über die Position der Kontinente bezüglich der Längengrade zulässt, ist dies mit den paläomagnetischen Daten vereinbar. Die alternativen Konfigurationen müssen jedoch alle vor dem Auseinanderbrechen Pangäas im Jura wieder in die für diesen Zeitraum allgemein akzeptierte Wegener-Konfiguration zurückgeführt werden. Dies geschieht - wiederum im Einklang mit den paläomagnetischen Daten - unter Beibehaltung der Breitenlage der Kontinente entlang einer postulierten kontinentalen dextralen Scherzone. Der Versatz von 2000 bis 3000 km fand laut Muttoni et al. (2003) in einem Zeitraum von ca. 20 Ma im frühen Perm statt. Dadurch ergibt sich eine entsprechend hohe Versatzrate von 10 bis 15 cm/a. Diese Arbeit befasst sich im Rahmen mehrerer paläomagnetischer Studien mit der Suche nach dieser großen Scherzone, deren Existenz seit Jahrzehnten umstritten ist. Der große Versatz wurde vermutlich von mehreren Störungssegmenten aufgenommen, die eine mehrere hundert Kilometer breite diffuse und segmentierte Scherzone bildeten. Paläogeographische Rekonstruktionen legen nahe, dass die Scherzone unter Anderem den Bereich des heutigen Mittelmeerraumes umfasst hat (Arthaud and Matte, 1977). Die Tizi-N'-Test-Verwerfung und ihre westliche Fortsetzung, die Süd-Atlas-Störung, sowie Verwerfungen entlang der nördlichen Pyrenäen und innerhalb des Armorikanischen Massivs (Bretagne) bilden demnach die Hauptblattverschiebungssysteme, die die Scherzone begrenzen. Krustenblöcke, die in entsprechend großen Störungssystemen liegen, können um vertikale Achsen rotieren (Nelson and Jones (1987) und darin zitierte Werke). Diese Rotationen können mit Hilfe der Paläomagnetik quantifiziert werden. Kapitel 1 leitet in die vorstehend beschriebene Problematik ausführlich ein und beleuchtet insbesondere die einzelnen Abschnitte dieser Arbeit. Somit wird deutlich, wie die Ergebnisse der Studien, aus denen sich die vorliegende Arbeit zusammensetzt, aufeinander aufbauen und einen konsistenten Lösungsansatz für die eingangs beschriebene Diskrepanz zwischen den Polwanderkurven Laurasias und Gondwanas entwickeln. Kapitel 2 beschreibt eine paläomagnetische Studie, die im Toulon-Cuers Becken, Südfrankreich durchgeführt wurde. Das Toulon-Cuers Becken entstand während einer Phase der Extension im südlichen variszischen Gürtel Europas, und ist sukzessive mit Sedimenten verfüllt worden. Außer mächtigen permo-triassischen Sedimentpaketen finden sich hier auch Laven und Pyroklastika als Produkte eines extensionsgetriggerten Vulkanismus, die ebenfalls Gegenstand der hier durchgeführten Studie sind. Die Ergebnisse der Untersuchungen können sehr gut mit bereits vorhandenen Literaturdaten in Einklang gebracht werden und zeigen, dass es zur fraglichen Zeit durchaus Bewegungen zwischen klar definierten Krustenblöcken gab, die Zeugen einer generellen Mobilität der Kruste in diesem Bereich sind. Es handelt sich hierbei um Blockrotationen um vertikale Achsen, so wie sie im Spannungsfeld einer kontinentalen Transformstörung zu erwarten sind. Dabei werden Rotationen im und gegen den Uhrzeigersinn dokumentiert, woraus eine komplexe Geometrie und Anordnung der Krustenblöcke abgeleitet werden kann. Hieraus wird ein tektonisches Modell entwickelt, welches mit gängigen Modellen (siehe McKenzie and Jackson (1983) in Nelson and Jones (1987)) in Einklang gebracht wird. Die triassischen paläomagnetischen Daten aus dem Gebiet belegen im Gegensatz dazu keine Rotationen und legen daher den Schluss nahe, dass die Krustenmobilität in dem Bereich zu Beginn des Mesozoikums zum Erliegen gekommen war. Somit belegt diese Studie deutlich, dass es im von Muttoni et al. (2003) postulierten zeitlichen Rahmen Hinweise für eine generelle Mobilität innerhalb Pangäas gibt. Unter Berücksichtigung dieser Ergebnisse wurde die folgende Studie an magmatischen Ganggesteinen ("Dykes") in Sardinien (Italien) durchgeführt, um die laterale räumliche Dimension der Scherzone besser abschätzen zu können. Kapitel 3 stellt die Ergebnisse dieser Studie vor. Die Dykes treten schwarmförmig auf und sind in einem Zeitraum zwischen 298 ± 5Ma und 270 ± 10Ma in den Korsika-Sardinien-Batholith intrudiert (Atzori and Traversa, 1986; Vaccaro et al., 1991; Atzori et al., 2000). Zusätzlich zu den Rotationen, die auch hier mittels paläomagnetischer Daten nachgewiesen werden konnten, gibt die Orientierung der einzelnen Dykeschwärme Aufschluss über das tektonische Spannungsfeld, das während der Platznahme der Dykes vorherrschte. Diese kombinierten Ergebnisse bestätigen und ergänzen die Ergebnisse der vorhergehenden Studie in Südfrankreich. Ergänzend zu den Untersuchungen an den Ganggesteinen Sardiniens werden Daten von permischen Sedimenten und Vulkaniten präsentiert, die in verschiedenen Regionen Sardiniens beprobt wurden (Kapitel 4). Die paläomagnetischen Daten belegen, dass Sardinien in mindestens zwei Krustensegmente zerlegt war, welche relativ zueinander und auch relativ zur europäischen Polwanderkurve rotiert sind. Auch hier wiederholt sich das Muster von Rotationen im und gegen den Uhrzeigersinn. In dieser Studie werden die Ergebnisse aus den vorangehenden Kapiteln sowie aus der weiterführenden Literatur zusammengefasst, so dass ein zeitlich und räumlich verfeinertes Bild der Krustenblöcke im westlichen Mittelmeerraum zur Zeit des frühen Perm entsteht. Durch die verbesserte Definition der Geometrie der einzelnen Blöcke kann das in Kapitel 2 beschriebene tektonische Modell bestätigt werden. Kapitel 5 befasst sich abschließend mit dem zeitlichen Rahmen der Aktivität entlang der fraglichen Scherzone. Ausgehend von der Annahme, dass sich die Kontinente im Jura bereits in einer Pangäa A Konfiguration befunden haben, sollten die paläomagnetischen Daten von jurassischen Gesteinen keine Hinweise auf Scherbewegungen geben. Hierzu wird eine Studie an jurassischen Sedimenten Sardiniens vorgestellt. Die paläomagnetischen Daten der untersuchten Krustensegmente belegen, dass es in post-jurassischer Zeit in Sardinien keine Blockrotationen der einzelnen Segmente relativ zueinander gab und Sardinien somit ab jener Zeit als tektonisch einheitlicher Block behandelt werden muss. Des Weiteren zeigen die paläomagnetischen Pole, die aus den paläomagnetischen Richtungen für eine Referenzlokalität berechnet wurden, keine signifikante Abweichung von der Polwanderkurve des europäischen Kontinents nach Besse and Courtillot (2002). Diese Kohärenz der paläomagnetischen Daten bestätigt die weithin akzeptierte Beobachtung, dass sich Pangäa zur Zeit des Jura bereits in der Wegener Konfiguration (Pangäa A) befunden hat und untermauert die Aussagekraft paläomagnetischer Studien in diesem Zusammenhang. Zugleich kann anhand dieser Daten ausgeschlossen werden, dass die alpidische Orogenese die Ursache für bedeutende Krustenblockrotationen in dieser Region gebildet hat. Die Ergebnisse der oben genannten Studien werden in dieser Arbeit zusammengeführt. Im Verbund mit Daten aus der Literatur untermauern sie, dass es zwischen dem frühen Perm und der frühen Trias entlang eines ausgedehnten Gürtels, der mindestens vom französischen Zentralmassiv über Südfrankreich bis nach Korsika- Sardinien reichte, bedeutende Krustenbewegungen in Form von Blockrotationen innerhalb Pangäas gab. Die vorliegende Synthese schafft somit ein konsistentes Bild der generellen Krustenmobilität zwischen den nördlichen Teilen Pangäas (Laurasia) und den Südkontinenten (Gondwana). Der durch die präsentierten Studien abgesteckte zeitliche Rahmen korreliert mit den Abschätzungen von Muttoni et al. (2003) zur Transformation zwischen verschiedenen Pangäakonfigurationen. Diese Arbeit bestätigt außerdem, dass das mittlere Perm eine Zeit großräumiger Reorganisation der kontinentalen Platten war, die von anhaltender magmatischer Aktivität begleitet war (Deroin and Bonin, 2003; Isozaki, 2009). Anhand der hier vorgestellten neuen Daten in Kombination mit bereits bekannten paläomagnetischen Daten aus der Region ergibt sich ein klares Muster von Rotationen im und gegen den Uhrzeigersinn von einzelnen störungsbegrenzten Krustenblöcken. Diese Arbeit belegt, dass die Paläomagnetik ein hervorragendes Instrument zur Quantifizierung jener Krustenblockrotationen ist, die oftmals die einzigen verbleibenden Indizien für ehemals großräumige Scherzonen bieten, nachdem die Störungen selbst aufgrund vielfältiger Prozesse nicht mehr aufgeschlossen sind (Umhoefer, 2000). Die tektonischen Modelle von McKenzie and Jackson (1983) in der Interpretation nach Nelson and Jones (1987) werden als Erklärungsgrundlage für die beobachteten Rotationen herangezogen und erweitert.

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Jul 08, 2015

Biological carbonate hard tissues, such as the shell of the bivalve Mytilus edulis, are composites of biopolymers and minerals. M. edulis has two distinct layers, the outer layer consists of fibrous calcite and the inner layer is composed of nacreous aragonite. Close to the interface between nacreous aragonite and fibrous calcite, a 1-2 micrometer wide zone exists that consists of granular aragonite. Aragonite granules and tablets as well as calcite fibrous are embedded into matrix biopolymers. In order to understand the composite nature of these hard tissues, biomimetic experiments using hydrogels were carried out. Hydrogels are able to model biogenic matrix environments due to their ability to confine space and to determine diffusion rates, local concentrations and supersaturation of the solutes. Hydrogels have local crystallization microenvironment that is distinguished from that in solution by confinement of solutes in the hydrogel pores. However, hydorgels only mimic biological extracellular matrices to some extent as the hydrogel fiber organization lacks any order, unlike it is in the case of the cholesteric liquid phase, e. g. chitin. The hydrogel strength is adjustable by changing its solid content. It further increases local hydrogel fiber co-aligments that to some extent will mimic organic matrices in biological hard tissues. Different kinds of hydrogels were used to study calcite crystallization (silica, agarose, gelatin). As each hydrogel has different characteristics, hydrogels can act differently in promoting or inhibiting crystallization. Hydrogels have an ability to mechanically impede the growth of a crystal depending on the strength of the hydrogel. Gelatin hydrogel is a poly-peptide material derived from natural collagen through hydrolytic degradation. The hyrolitic degradation breaks the triple-helix structure of collagen into single-strand molecules. Gelatin contains both acidic and basic amino acids with isoelectric point values near ∼5 and with predominance of acidic moieties. Agarose hydrogel is a linear polysaccharide extracted from marine red algae. It consists of beta-1,3 linked D-galactose and alpha-1,4 linked 3,6-anhydro-alpha-L-galactose residues. Gelatin and agarose hydrogels are composed of a fibrous structure that have varying mesh void dimensions depending on the hydrogel solid content. Hydrogel with 2.5 wt % gelatin solid content exerts less pressure against the growing calcite crystal aggregate than a hydrogel with 10 wt % gelatin solid content. Silica hydrogel does not exert strong pressure against the growing calcite crystal aggregate due to its nature as it is composed of minute (less than 20 nm) sized spherical particles that do not appear to form a network. The hydrogel strength together with the growth rate of the crystal defines the amount of incorporated hydrogel into the growing calcite crystal aggregate such that a strong hydrogel will incorporate more gel into the calcite crystal than a weak hydrogel. Calcite grown in Mg-free silica hydrogels has a rhombohedral shape and is elongated on the c-axis. It grows as dumbbell-shaped aggregates in the presence of Mg. Silica hydrogel either Mg-free or Mg-bearing does not give a major influence on the co-orientation of the obtained crystal aggregate. Calcite grown in Mg-free agarose has two morphologies: rhombohedron-shaped calcite crystals and calcite radial aggregates. Calcite grown in Mg-bearing agarose has sheaf-like and peanut like morphologies. The presence of Mg in agarose influences the co-orientation of calcite crystals within calcite Mg-bearing agarose composites. The calcite/Mg-free agarose composite has several large crystal subunits while the calcite/Mg-bearing agarose composite shows a spherulitic microstructure. In the case of gelatin hydrogel, the precipitate consists of calcite aggregates that have a variety of features i.e. the formation of mosaic crystals and mesocrystal-like subunits in one aggregate, the formation of aggregates with a fan-like distribution of the c-axis orientation and the formation of spherulitic aggregates. The formation of aggregates with different characteristic in the subunits can be explained as a result of a combination between local differences in gelatin matrix arrangement and physicochemical conditions such as the change in Mg/Ca ratio, pH, saturation, etc. The development of a fan-like distribution of the c-axes orientation in the calcite aggregate subunits can be explained as a result of Mg intrasectorial zoning. A different degree of Mg incorporation in different growth steps will accumulate misfit strain in the lattice. This misfit strain could be released through the formation of dislocations at regular intervals, such that small-angle boundaries develop. This growth further leads to the extreme split growth and the formation of fan-like and spherulitic crystal aggregates. The etching experiments of calcite/hydrogel composites reveal the structure of the incorporated hydrogel within the calcite crystals and aggregates. In the case of Mg-bearing silica hydrogel more silica hydrogel is incorporated into the calcite crystal than in the case of Mg-free silica hydrogel. Thick hydrogel membranes are observed when Mg-free gelatin and agarose hydrogels are used. These membranes do not occur when Mg is present. The formation of these membranes in Mg-free gelatin and agarose hydrogels is a result of an accumulation of the hydrogel fibers that are driven back by growing crystals or aggregates. The stiffness of the gelatin and agarose hydrogel fibers increase as Mg is added into the hydrogel. The hydrogel becomes stiffer and exerts more pressure against the growing aggregates. No hydrogel membranes are observed in aggregates grown in Mg-bearing gelatin and in agarose hydrogels. On the basis of biopolymer and mineral composites, gypsum (CaSO4)/cellulose fiber composites were prepared. The purpose of the addition of cellulose fiber to gypsum was to create a composite with a high ecological value and interesting mechanical properties such as high Young’s modulus, high bending strength and high compression strength. The cellulose fiber affects the mechanical property of the composites depending on the fiber characteristics, e.g. the nature of the cellulose (natural or synthetic), water retention value, degree of swelling, etc. Lyocell fiber, a synthetic fiber, is found to be able to increase the Young’s modulus of the final composite.

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May 26, 2015

Problem. More than ever, some of the biggest challenges to society involve governance of natural resources. From large-scale resource systems such as the rain forest and oceans to small-scale systems such as lakes or alpine pastures, cooperative efforts are required to ensure sustainable and yet productive use of natural resources. In Switzerland, the management of alpine pastures has for centuries been predominantly organized by local governance institutions, avoiding an overuse of the scarce resources. During the past decade, the use and maintenance of common property pastures (CPP) is declining, leading to land abandonment and forest regrowth. However, CPP provide significant services to the mountain regions, such as additional grazing grounds, assets for the tourism industry, protection from soil erosion, water run-off and landslides, and high biodiversity. These services are currently threatened by reduced use and maintenance of the CPP. Research Aims. The research presented herein aims for a better understanding of social-ecological interactions driving the use of CPP to provide policy recommendations for the sustainable governance of CPP. Methods. To generate a holistic understanding of the variables driving CPP use, this research used multiple methods to investigate CPP use in Grindelwald, Switzerland as a social-ecological system (SES). The research was structured in 4 modules. First, qualitative methods were applied to analyze institutional change in the governance of CPP. Second, regression models were built from survey data to better understand farmers’ land-use decision. Third, an analysis of the ecological system was conducted bases on land-cover statistics. Forth, a systems dynamics model of the local SES was built and combined with formative scenario analysis to investigate potential future developments of CPP use. Results. The outcomes of the different modules suggest that: First, local governance systems originally designed to prevent overuse of CPP are able to adapt to problems of declining use and maintenance of CPP by altering a set of rules. Second, farmers’ use of CPP depend on personal attributes, including farm size, norms, and dependence on the resource. Furthermore, the analysis suggests that high local demand and prices for alpine cheese are a central factor in the sustainable use of CPP. Third, the land-cover analysis showed that afforestation occurs in Grindelwald at a relatively moderate pace and defines the area most prone to afforestation and bush encroachment. Fourth, the simulation model allows for the display of complex social-ecological interactions, showing that afforestation tendencies are likely to continue, although at different pace depending on the scenario setting. Conclusion. This research provides a better understanding of CPP use through the analysis of the subsystem characterizing the SES. It showed how the general framework for analyzing social-ecological systems can be operationalized using a broad set of methods. It thereby contributed and advanced central themes within the study of the commons such as institutional analysis, users’ behavior in cooperative dilemmas, and modeling of SES. The integration of the findings from different modules into a simulation provided insights about the effects of different policies on the sustainability of the SES, and thereby demonstrated why particular policy blueprints will rather accelerate than counteract the problem of CPP abandonment.

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Apr 30, 2015

The Central Asian Orogenic Belt (CAOB) is one of the world's largest accretionary orogens, which was active during most of the Paleozoic. In recent years it has again moved into focus of the geological community debating how the acrreted lithospheric elements were geographical arranged and interacting prior and/or during the final amalgamation of Kazakhstania. In principal two families of competing models exist. One possible geodynmaic setting is based on geological evidence that a more or less continuous giant arc connecting Baltica and Siberia in the early Paleozoic was subsequently dissected and buckled. Alternatively an archipelago setting, similar to the present day south west Pacific was proposed. This thesis collates three studies on the paleogeography of the south western part of the CAOB from the early Paleozoic until the latest Paleozoic to earliest Mesozoic. It is shown how fragments of Precambrian to early Paleozoic age are likely to have originated from Gondwana at high southerly paleolatitudes (~500 Ma), which got then accreted during the Ordovician (~460 Ma), before this newly created terrane agglomerate (Kazakhstania) migrated northwards crossing the paleo-equator. During the Devonian and the latest Early Carboniferous (~330 Ma) Kazakhstania occupied a stable position at about ~30°N. At least since this time the area underwent several stages of counterclockwise rotational movements accompanying the final amalgamation of Eurasia (~320 - ~270 Myr). This overall pattern of roughly up to 90° counterclockwise bending was replaced by internal relative rotational movements in the latest Paleozoic, which continued probably until the early Mesozoic or even the Cenozoic. In Chapter 2 a comparison of declination data acquired by a remagnetization process during folding in the Carboniferous and coeval data from Baltica and Siberia lead to a documentation and quantification of rotational movements within the Karatau Mountain Range. Based on this results it is very likely that the rotational reorganization started in the Carboniferous and was active until at least the early Mesozoic. Additionally, the data shows that maximal declination deviation increases going from the Karatau towards the Tianshan Mountains (i.e. from North to South). This observation supports models claiming that Ural mountains, Karatau and Tianshan once formed a straight orogen subsequently bent into a orocline. The hinge of this orocline is probably hidden under the sediments of the Caspian basin. In chapter 3 we show that inclination shallowing has affected the red terrigenous sediments of Carboniferous age from the North Tianshan. The corrected inclination values put this part of the Tianshan in a paleolatitude of around 30°N during Carboniferous times. These results contradict previously published paleopositions of the area and suggest a stable latitudinal position between the Devonian and the Carboniferous. Chapter 4 presents paleomagnetic data from early Paleozoic rocks from within the North Tianshan. They imply a second collisional accretion event of individual terranes in the Ordovician. To further constrain the dimensions of these early Paleozoic terranes, chapter 5 presents a compilation of all available paleomagnetic data from the extended study region of southern Kazakhstan and Kyrgyzstan. Apart from a broad coherence of paleolatitudes of all studies at least since the Ordovician and the exclusive occurrence of counterclockwise declination deviations, no areas with the same rotational history can be detected. Also a clear trend caused by oroclinal bending can not be observed. We conclude that first order counterclockwise oroclinal bending, shown in chapter 2, resulted in brittle deformation within the mountain belt and local block rotations. In order to improve our understanding of intra-continental deformation a study combining the monitoring of recent deformation (Global Positioning System, GPS) with a paleomagnetic study of Cenozoic age in the greater vicinity of the Talas-Ferghana fault has been undertaken in chapter 6. The major task was to distinguish between continuous versus brittle deformation. As it turned out the GPS signal indicates rather continuous and consistent counterclockwise rotational movements of the order of ~2° per Myr. This is in contrast to our paleomagnetic results, where even within fault bounded areas the error intervals of the rotations do always overlap. This indicates that a pure block model seems not appropriate even to explain Cenozoic paleomagnetic data. If this means that also Paleozoic rocks have been affected by complex recent deformation, and that the Paleozoic rotational pattern has been obscured by this, can not be decided based on the present data set. It means, however, that interpreting Paleozoic rotational data from this area has to be done with great caution.

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Apr 29, 2015

The scientific investigation of the solid Earth's complex processes, including their interactions with the oceans and the atmosphere, is an interdisciplinary field in which seismology has one key role. Major contributions of modern seismology are (1) the development of high-resolution tomographic images of the Earth's structure and (2) the investigation of earthquake source processes. In both disciplines the challenge lies in solving a seismic inverse problem, i.e. in obtaining information about physical parameters that are not directly observable. Seismic inverse studies usually aim to find realistic models through the minimization of the misfit between observed and theoretically computed (synthetic) ground motions. In general, this approach depends on the numerical simulation of seismic waves propagating in a specified Earth model (forward problem) and the acquisition of illuminating data. While the former is routinely solved using spectral-element methods, many seismic inverse problems still suffer from the lack of information typically leading to ill-posed inverse problems with multiple solutions and trade-offs between the model parameters. Non-linearity in forward modeling and the non-convexity of misfit functions aggravate the inversion for structure and source. This situation requires an efficient exploitation of the available data. However, a careful analysis of whether individual models can be considered a reasonable approximation of the true solution (deterministic approach) or if single models should be replaced with statistical distributions of model parameters (probabilistic or Bayesian approach) is inevitable. Deterministic inversion attempts to find the model that provides the best explanation of the data, typically using iterative optimization techniques. To prevent the inversion process from being trapped in a meaningless local minimum an accurate initial low frequency model is indispensable. Regularization, e.g. in terms of smoothing or damping, is necessary to avoid artifacts from the mapping of high frequency information. However, regularization increases parameter trade-offs and is subjective to some degree, which means that resolution estimates tend to be biased. Probabilistic (or Bayesian) inversions overcome the drawbacks of the deterministic approach by using a global model search that provides unbiased measures of resolution and trade-offs. Critical aspects are computational costs, the appropriate incorporation of prior knowledge and the difficulties in interpreting and processing the results. This work studies both the deterministic and the probabilistic approach. Recent observations of rotational ground motions, that complement translational ground motion measurements from conventional seismometers, motivated the research. It is investigated if alternative seismic observables, including rotations and dynamic strain, have the potential to reduce non-uniqueness and parameter trade-offs in seismic inverse problems. In the framework of deterministic full waveform inversion a novel approach to seismic tomography is applied for the first time to (synthetic) collocated measurements of translations, rotations and strain. The concept is based on the definition of new observables combining translation and rotation, and translation and strain measurements, respectively. Studying the corresponding sensitivity kernels assesses the capability of the new observables to constrain various aspects of a three-dimensional Earth structure. These observables are generally sensitive only to small-scale near-receiver structures. It follows, for example, that knowledge of deeper Earth structure are not required in tomographic inversions for local structure based on the new observables. Also in the context of deterministic full waveform inversion a new method for the design of seismic observables with focused sensitivity to a target model parameter class, e.g. density structure, is developed. This is achieved through the optimal linear combination of fundamental observables that can be any scalar measurement extracted from seismic recordings. A series of examples illustrate that the resulting optimal observables are able to minimize inter-parameter trade-offs that result from regularization in ill-posed multi-parameter inverse problems. The inclusion of alternative and the design of optimal observables in seismic tomography also affect more general objectives in geoscience. The investigation of the history and the dynamics of tectonic plate motion benefits, for example, from the detailed knowledge of small-scale heterogeneities in the crust and the upper mantle. Optimal observables focusing on density help to independently constrain the Earth's temperature and composition and provide information on convective flow. Moreover, the presented work analyzes for the first time if the inclusion of rotational ground motion measurements enables a more detailed description of earthquake source processes. The complexities of earthquake rupture suggest a probabilistic (or Bayesian) inversion approach. The results of the synthetic study indicate that the incorporation of rotational ground motion recordings can significantly reduce the non-uniqueness in finite source inversions, provided that measurement uncertainties are similar to or below the uncertainties of translational velocity recordings. If this condition is met, the joint processing of rotational and translational ground motion provides more detailed information about earthquake dynamics, including rheological fault properties and friction law parameters. Both are critical e.g. for the reliable assessment of seismic hazards.

1s

Jul 10, 2014

Remote sensing has become an essential tool to improve data collection and spatial analysis in the geosciences. Identification of passive margin structures that are exposed along the Egyptian coast of the Red Sea, and their control on landforms has been hampered by limited data resolution and restricted access to this arid and inaccessible region. A major challenge lies in distinguishing features in the landscape that formed due to long-term tectonic activity and erosion from those features that modified the landscape recently. The goals of this thesis were to determine to what degree the study area is currently tectonically active, and what major hazards might affect the touristically developing coastal region. This study deals with the structural and geomorphological evolution of the rift-related structures and their impact on the sediment distribution and landforms variation in the northern Quseir area. In such a remote desert area, field and remote morphostructural analysis are needed to understand the structural and geomorphological evolution. The current study is mainly based on high-resolution QuickBird image analysis and field investigation. Field mapping was limited to one season, owing to acute safety concerns in the Eastern Desert. In the study area, the pre-rift stratigraphy includes Pan-African basement rocks overlain by pre-rift clastic and carbonate successions that range in age from Cambrian to Eocene. Syn-rift clastic and carbonate rocks range in age from Late Oligocene to recent and show depositional patterns controlled by fault systems. The field area exposes a section of a tectonically uplifted, amagmatic sedimentary sequence, which formed due to passive-margin-related rifting of the Red Sea: the Mesozoic and Tertiary sedimentary units that fill the 7-km wide coastal strip are perfectly exposed as tilted fault blocks. The results of my field mapping and structural analysis show that the fault architecture of the area is dominated by a large NW-SE-striking fault system. A series of SE-dipping normal faults are consistent in cross-section with listric fault geometry, rooting into an E-dipping detachment at depth. Our mapping also revealed that left-steps in at least one of the major NS- striking faults are accommodated by a flower structure, but not by SW-NE-oriented cross faults as previously proposed in a neighboring area. Thus seismic activity is more likely to occur on the large NW-striking normal faults, leading to potentially larger Magnitude earthquakes than previously recognized in the area. The left-step may act as a barrier to rupture propagation and should be examined in more detail. The northwestern Red Sea coast is part of the straight coastal segment that is generally characterized as seismically inactive. However, during the geological field mapping, I found evidence for Plio-/Pleistocene vertical coastal uplift, likely due to earthquake-related coastal and offshore faulting. Pliocene marine deposits emerged recently due to sea level-drop and earthquake-related uplift. Even the presence of up to five distinct Pleistocene coral terraces implies that at least some of the coastal uplift was seismogenic, because terraces of the same age can be found at different elevations along strike. Presumably, some of the seawarddipping, N-S-striking normal faults are active today, despite the lack of recent instrumental seismicity. These findings imply long recurrence intervals for active faults in the northern Quseir area. These results differ from previously published results for the adjacent Quseir-Um Gheig sub-basin area, were E-W-striking strike-slip faults were mapped to offset the N-Sstriking faults, and had been inferred as earthquake-generating faults by Abd El-Wahed et al. (2010). Based on our mapping, we postulate that the large rift-parallel normal faults are seismogenic. Drainage network evolution within the study area is often structurally controlled and the nature of these controls was examined in this study. The Wadi Siatin stream channel network is classified in a relatively simple way, based on the high-resolution satellite data, with dendritic, and rectangular considered the most fundamental channel geometries. It was possible to distinguish the different morphological elements of the network, as well as the anomalies that affect the patterns. This analysis revealed, in the northern Red Sea area basins, the existence of old structures whose successive reactivations have left their mark on the drainage network. Comparison of joint systems direction with the directions of the main trunk stream channel of Wadi Siatin shows that the channel is highly affected by tectonic jointing. First-order channels follow easily erodable faults. Investigations concerning the relationship of stream-flow orientation with geological structure in the Wadi Siatin Basin shows that, generally, the least influenced flows are those of first-order which are governed simply by the valley side slopes on which they developed. However, in certain geological and geomorphological situations, there are clear exceptions to this generalization. Certainly, locally, geological control of these small streams may be even higher than in many streams of higher order. In the peripheral parts of the Basin, expansion of drainage into the available space has obviously been easiest along lines of weakness and, as a consequence of this, streams of the first order come to exhibit a high degree of adjustment to the underlying structure. The maximum structural control is reached by the streams of the third order. Towards the higher orders, the influence of local structure becomes weaker.

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Jun 11, 2014

The study deals with the two main problems in geographical education: How to inform students about a spatial practicing learning and teaching and how to evaluate this form of learning in comparison to theoretical non spatial forms of learning. The classic form of spatial learning is the outdoor excursion. But there are some new and actual alternatives when realizing the former intended aims of a spatial learning, so for instance didactical pathways, field trips or field works, but also the new way of geocaching and learning by GPS when dealing with the themes of orientation or finding out points of geographic importance for explaining the genetic processes. The necessary skills can be combined to improve the success of learning and to maximize the motivation. The base of this motivation behavior is the existence of a hide and seek-game as a modern version of a scavenger hunt. This motivates the students and is furthermore the attraction of Geocaching. Methodical skills can also be trained very automatically during this search. The GPS devices are of common use in the daily life and its use may increase much more in the fu-ture and in geographical use, too. Nowadays the literature about this theme is merely descriptive and thematically reduced to the function of orientation. The first study describing the learning suc-cess of using GPS devices and Geocaches in geography class had been made by NEEB. She tested the variation of the competence of orientation in different old classes when examining the use of GPS devices and Geocaches. Even though GPS devices and Geocaches are very efficient for instructing the students’ competence of orientation there may be the question, in what forms and circumstances the learning can be done. The time and effort necessary to generate a didactical and educational trail has to be justified against the background of the achieved learning effect. Educational trails need students, walking outside of the schools, looking for information along teaching paths and learning by the results. This active experienced learning leads to a better understanding of the environment, the outdoor circumstances and the people living in this area. You can structure such educational trails by Geopoints, this means points of a special geographic interest. Geocaches can structure such paths didactically. These structuring points are GEOpoints. The tasks at such Geopoints are structured didactical as well. GPS devices and Geocaches are complementing one another. They fulfill an important function in geographic orientation and the respective local information. Two important ministries in Germany (Bavaria, Baden-Württemberg) demand the use of extra¬curri-cu¬lar educational objectives in geography education. This means: visiting locations outside of the school and using the advantages of a fully learning by excursions. Neurobiology supports the idea that pupils completing the educational trail will learn much more and efficiently than students in “normal” classes: Indeed: A successful contextualization of modern geomedia stimulates the motivation. Geocaches are suitable for didactical structuration and motivation. A better and more comprehensive addressing to all senses will lead to a better sustainability. When testing the advantage of excursional learning comparing the same themes with a classical learning at school you have to differ within the students capacity of learning and the cognitive and methodical competence. For 17years aged students the theme of “Umgestaltung von Flusslandschaften“ (rearrangements of fluvial topography) was chosen because using this example of anthropogenic rearrangements of the Rheinaue wetlands near Karlsruhe shows the interdependency between human and environment was in the direct neighborhood of the students. Therefore the excursion could be realized very good without long transports. The “Nördlinger Ries” between the Swabian and the Franconian Jura is an impact-crater of world-wide importance. This location had been chosen for Students of grade 5 (10 years old students). The themes to work out were: The typical elements of the Swabian Jura (karst formation, hydrogeology, typical vegetation) and the special forms of the impact tectonics. The sustainability of educational trails using GPS had been evaluated by the answers of 441 ques-tionnaires. In grade 5 a multiple-choice-test had to be answered while grade 11 had to answer open questions in complete sentences. The influence of the teachers on the overall result is being kept low through the random selection, the number of the comparison groups and the teaching manuals. The overall results of these questionnaires show that the students of grade 5 which completed the educations trail achieved 11% higher scores in areas of the cognitive performance compared to the students who experienced classical learning at school. In grade 11 the students who completed the educational trail received 5% higher scores. Both differences in the results are significant and show a magnitude of effect, which is high in certain items. Consequently, the study has proven that educational trails evocate better cognitive performances than classical learning at school. The current state of research suggests that the development of environmental trails from teachers for teachers is not sustainable because the teachers don’t have the time to refine environmental trails didactically. The experience while creating the educational trails and the feedback of the participant teachers showed that teachers should cooperate for creating educational trails. The strain for each single person is reduced and the regularly use of the educational trails can be assured.

1s

Jun 04, 2014

Seismische Tomographie ist die eindrücklichste und intuitivste Methode, Informationen über das tiefe Erdinnere, von der Kruste bis an die Kern-Mantel-Grenze zu erlangen. Die von entfernten Erdbeben aufgezeichneten Bodenbewegungen werden mit den für ein einfaches Erdmodell vorhergesagten verglichen, um ein verbessertes Modell zu erhalten. Dieses dreidimensionale Modell kann dann geodynamisch oder tektonisch interpretiert werden. Durch die Entwicklung leistungsfähiger Computersysteme kann die Ausbreitung seismischer Wellen mittlerweile im gesamten messbaren Frequenzbereich simuliert werden, sodass dieses gesamte Spektrum der Tomographie zur Verfügung steht. Die vorliegende Arbeit beschäftigt sich mit der Verbesserung der Wellenformtomographie. Zum einen wird die Nutzbarkeit eines komplexen Typs seismischer Wellen, der in der Mantelübergangszone zwischen 410 und 660 km Tiefe gestreuten triplizierten Wellen ge-zeigt. Diese Wellen versprechen eine erheblich bessere Auflösung der geodynamisch wichtigen Diskontinuitäten zwischen oberem und unterem Mantel als bisher verwendete teleseismische Wellen. Zum anderen wird der nichtlineare Einfluss des Erdbebenmodells auf die Wellenformtomographie untersucht. Mittels Bayesianischer Inferenz werden Wahrscheinlichkeitsdichten für die Herdparameter des Erdbebens, wie Tiefe, Momententensor und Quellfunktion bestimmt. Dazu wird zuvor ein Modell der Messunsicherheit und des Modellierungsfehlers in der Herdinversion bestimmt, das bis dato nicht vorlag. Dabei zeigt sich im Weiteren, dass der Effekt der Unsicherheit im Herdmodell eine nichtlineare und bisher weitgehend ignorierte Feh-lerquelle in der seismischen Tomographie ist. Dieses Ergebnis ermöglicht es, die Varianz seismischer Laufzeit- und Wellenformmessungen sowie die Kovarianz zwischen einzelnen Messstationen zu bestimmen. Die Ergebnisse dieser Arbeit können in Zukunft erheblich dazu beitragen, die Unsicherheiten der seismischen Tomographie quantitativ zu bestimmen, um eventuell vorhandene Artefakte zu zeigen und damit geologischen Fehlinterpretationen tomographischer Ergebnisse vorzubeugen.

1s

Apr 16, 2014

Summary Problem. Pesticides play an important role in the agricultural production but their misuse affect the health of farmers and workers who manipulate such toxic substances. In the field of occupational hygiene, researches have been working in finding out the most appropriate method to estimate the human exposure in order to assess the risk and therefore to take the due decisions to improve the processes in the pesticide management and to reduce the health risk. Goals. The goal of this research was focused in creating a model for human exposure assessment specially for farming systems in developing countries by (i) evaluating the available models for human exposure assessment developed in industrialized countries, (ii) measuring the exposure in the study areas of potato and flower farming systems in Colombia, and (iii) proposing a pesticide flow model to estimate quantitatively the human exposure. Methods. The research was organized in three phases by using different methods, namely (i) evaluation of previous models of human exposure assessment (by means of a Multi-Criteria and Sensitivity Analysis); (ii) quantification of dermal exposures in Vereda La Hoya (by applying the Whole Body Dosimetry, Luminiscence Spectrometry and Tracer Method); and (iii) the development of a pesticide flow model for the human exposure assessment (by applying the Material Flow Analysis method). This model was built with dermal exposure measurements obtained in the study area of greenhouse flower crops in Sabana de Bogotá, Colombia. Results. DERM, DREAM, PHED and RISKOFDERM were selected as the most appropriate models to be applied in farming systems in developing countries as their determinants are relevant for the assessment of pesticide use and all the processes involved during the pesticide management. Afterwards these four models were applied to assess the dermal exposure in the case study of Vereda La Hoya and their determinants were compared with the characteristics of the study area, DREAM and DERM were found as the most appropriate models to assess the dermal exposure in these study areas. However, because some relevant determinants are still absent, the accuracy of these models could be improved if these are included. When comparing the final model assessment of dermal exposure in the study area, DREAM was found as the model that assesses more accurately the dermal exposure in this study area. In the study area of Vereda La Hoya, Colombia was found that the application was the activity with the highest PDE. Even though lower body parts (thighs and legs) were the most exposed, these body parts also showed the highest level of protection because of the work clothing. The ADE was high for arms and upper back due to the lack of adequate work clothing covering the complete arm and the direct contact of the upper back with the spills on the sprayer tank. Furthermore, it was found that Metamidophos is the most toxic pesticide used in Vereda La Hoya. Farmers may reduce significantly the health risk by using adequate work clothing made of appropriate fabrics that covers the whole body including the arms, cleaning properly all the pesticide residues left on the sprayer before each application, and avoiding the modification of nozzles using only nozzles with the standard discharge. The proposed pesticide flow model helps to identify the patterns of pesticide distribution on the body, the level of protection given by personal protective equipment and the estimates of potential and actual dermal and inhalation exposure. This information can be used to determine the health risk level by comparing the model estimates with the AEOL reference values for each pesticide. In addition, the model makes it possible to easily identify the activities or body parts that have high levels of exposure. This is useful in identifying improvements that will decrease the exposure during pesticide management. Because it is not feasible to measure directly the dermal exposure in all study areas, this model might help to obtain a quick estimation which could help stakeholders and authorities to make further decisions. Conclusions. This research evaluated in depth the available models for human exposure assessment, so assessors can decide which model is the most appropriate according to the characteristics of the study area in which the model is going to be applied and furthermore this research suggested improvements in the models in order to increase the estimation accuracy. This research also contributes in the proposal of a new model for human exposure based on the material flow analysis methodology studying the pesticide fractioning during the pesticide management in a certain interval of time. With this model quantitative estimations of human exposure are obtained which facilitate the risk assessment and the implementation of measures to improve the safety during the pesticide management and to decrease the risk. The proposed model also demonstrates the feasibility of applying the material flow analysis methodology in the field of human exposure, obtaining a tool that helps to understand the mechanisms of distribution of the pesticide in the farming system based on the processes involved and the flows between these processes.

1s

Feb 07, 2014

In order to increase our understanding of magma mixing processes and their impact on the geochemical evolution of silicate melt we present in the following works, the first set of experiments performed using natural basaltic and rhyolitic melts. In particular, we investigate the interplay of physical dynamics and chemical exchanges between these two melts using time-series mixing experiments performed under controlled, chaotic, dynamical conditions. The variation of major and trace elements is studied in detail by electron microprobe (EMPA) and Laser Ablation ICP-MS (LA-ICP-MS) and the time-evolution of chemical exchanges during mixing is investigated. Using the concentration variance as a proxy to measure the rate of chemical element homogenization in time, a model to quantify chemical element mobility during chaotic mixing of natural silicate melts is proposed. The morphology of mixing patterns at different times is quantified by measuring their fractal dimension and an empirical relationship between mixing time and morphological complexity is derived. The complexity of mixing patterns is also compared to the degree of homogenization of chemical elements during mixing and empirical relationships are established between the fractal dimension and the variation of concentration variance of chemical elements in time. Finally we discuss the petrological and volcanological implications of this work.

1s

Jan 14, 2014

The evolution of the vertebral column is marked by profound morphological changes that have a strong impact on organismal biology. The vital functions of the axial skeleton range from protecting the neural structures through sustaining the body posture to physiological aspects such as breathing. Archosaurs (crocodiles, birds and dinosaurs), as a group, display a striking variety of body plans and vertebral morphologies. This dissertation aims to contribute to the understanding of the pattern and the genetic basis for the evolution of the vertebral column in archosaurs. The transdisciplinary project comprises five chapters. Framed by a general introduction (chapter 1) and the conclusion (chapter 5), the second chapter considers, from a morphofunctional point of view, the question of (1) why differences in the vertebral column evolved. The present thesis revealed a strong link between the digitally simulated flexion pattern of the presacral vertebral column and the axial movements of modern archosaurs during related activities such as feeding and locomotion: this correlation allowed the inference of the feeding range and locomotor options in the extinct archosaur Plateosaurus. This long-necked dinosaur was primarily adapted as mid-level browser, obtaining food that was at or above the horizontal level of its head. There is currently no evidence to unambiguously interpret the locomotion style of Plateosaurus. The morphofunctional analysis supported both a quadrupedal and a bipedal posture. The third chapter addresses, from a molecular biology point of view, the question (2) of how modern taxa develop their vertebral columns. It provides insights into the genetic basis for the embryonic development of the vertebral column in modern archosaurs, which includes the highly conserved Hox genes. The Hox gene expression pattern was detected in the Nile crocodile (Crocodylus niloticus) via whole-mount in situ hybridisation experiments. Hox paralog genes 4 and 5 are expressed in the cervical region of the crocodile. The anterior expression limit of HoxC-6 marks the cervicothoracic transition. The expression of Hox paralog genes 7 and 8 is restricted to the dorsal series. The same Hox genes are expressed along the anteroposterior body axis of crocodiles, chickens and mice, but the pattern of expression is different. The comparative analysis revealed two general processes that are accompanied by evolutionary differences in the axial skeleton: 1) expansion and condensation as well as 2) a shift of genetic activity corresponding to different vertebral counts. The strong association between the anterior limits of the expression of specific Hox genes and the borders between morphological regions of the vertebral axis in a variety of vertebrate species stimulated the work presented in the fourth chapter. It considers the question (3) of whether we can infer that the development of the vertebral column took place in extinct animals. The direct correlation between vertebral Hox code and quantifiable vertebral morphology shows that the genetic code is deducible from vertebral morphology in modern crocodiles, chickens and mice. Applying these findings to the fossil relative Plateosaurus revealed that the hypothetical Hox code for the dinosaur would be generally similar to the crocodilian Hox gene expression pattern, but with the variation that the anterior region is expanded, as in birds. The integrative analysis (morphology, genes and fossils) of the vertebrae greatly enhanced our knowledge of evolutionary processes and provided valuable information about the possible reasons, genetic basis and pattern for evolutionary changes of the vertebral column in extant and extinct archosaurs.

1s

Dec 20, 2013