This thesis investigates all-optical switching and domain wall (DW) dynamics in GdFe ferrimagnetic alloys following femtosecond laser excitation. Advanced magnetic imaging techniques, including photoemission electron microscopy (PEEM) and Kerr microscopy, are used to capture the magnetic behavior of the sample. The study examines single-pulse all-optical toggle switching, where the magnetization of the films is reversed by a single p-polarized laser pulse, independent of the initial magnetization direction. Specifically, we investigate the mechanisms behind deviations from deterministic toggle switching, especially near magnetic domain walls. The study reveals that non-deterministic switching arises from intrinsic factors, such as domain wall elasticity and laser-induced motion related to the sample itself, as well as extrinsic factors, like laser pulse variations, which depend on the setup. Further, double pulse excitation experiments probe the fastest toggle-switching frequency, where two laser pulses with an adjustable time delay between them excite the sample. By using different fluence ratios of the pulses as a function of the time delay, the experiments explore the role of fluence in re-switching. It was found that re-switching occurs within a time delay between 4 and 40 ps after the first pulse, with optimal conditions when the first pulse is just above the single-pulse switching threshold and the fluence of the second pulse is 0.5–0.7 times that of the first pulse. Atomistic spin dynamic simulations support these findings, offering insights into cooling dynamics where re-switching requires that electron and lattice temperatures equilibrate. We also investigated the behavior of the sample at time delays of 2 ps or less between pulses, following double-pulse switching at two temperatures, one below (70K) and one above (room temperature) the magnetic compensation temperature. Findings indicate that the threshold fluence required to induce multi-domain formation or demagnetization varies with the sample’s initial temperature, with more deterministic toggle switching observed at the lower temperature of 70K. Notably, the switching probability rises drastically at these short time delays, where the second pulse significantly amplifies the effect of the first, even if one or both pulses are below the threshold fluence of single pulse switching. Additionally, we examine DW motion in GdFe thin films with an in-plane easy axis under laser excitation. Depending on the DW’s position relative to the laser spot, either entropic torque or magnon spin transfer torque may dominate the motion. Although we did not identify a single, consistent direction of DW movement, it is evident that for DW motion, the DWmust be located within the (σx) region of the laser spot. Together, these findings advance our understanding of high-speed, energy-efficient magnetic switching and DW control, with promising implications for ultrafast magnetic storage technologies.

The increasing need to reduce atmospheric CO₂ emissions has driven interest in the electrochemical CO₂ reduction reaction (CO₂RR) as a sustainable approach for converting CO₂ into valuable chemicals. However, the development of efficient electrocatalysts for CO2RR to target products remains challenging due to the high overpotential and low selectivity. This thesis explores the design and performance of copper (Cu)-based foam electrocatalysts, with an emphasis on their potential to enhance the electrochemical conversion of CO₂ into multi-carbon products, such as ethanol and ethylene. In addition to developing robust electrocatalysts for efficient CO2RR, the goal was to follow the composition and structural transformations of the catalysts and reaction intermediates under operating conditions using operando spectroscopies, complemented by ex-situ methods. Operando X-ray absorption spectroscopy (XAS) revealed that bulk oxidation state transitions in oxide-derived Cu (OD-Cu) catalysts occur over tens of minutes, with kinetic trapping of subsurface oxygen species. In contrast, surface-enhanced Raman spectroscopy (SERS) indicated rapid oxide-to-metal transitions on the catalyst surface within seconds. Surface adsorbed hydroxides and carbon-containing intermediates were identified, suggesting their role in facilitating *CO adsorption and enhancing multi-carbon selectivity. A morphology-control strategy was implemented to optimize alcohol selectivity. Introducing NaCl during electrodeposition altered the OD-Cu structure, significantly improving faradaic efficiency for alcohol production. Enhanced electrochemical surface area per Cu atom promoted co-adsorption of *OH and *CO, favoring ethanol formation. The foam catalyst design was extended to bimetallic Cu-In and Cu-Sn systems to further modulate CO₂RR selectivity. Depending on the Cu-to-M (In or Sn) ratio, these catalysts preferentially produced CO or formate. XAS and SERS analyses revealed that Cu-In and CuSn catalysts undergo dynamic structural transformations, with surface copper oxides converting into mixed hydroxides and carbonates before reduction. Despite differences in composition, specific Cu-M ratios resulted in similar CO₂RR selectivity, highlighting the role of secondary metals in tuning catalytic performance. In conclusion, a combination of bulk- and surface sensitive operando spectro-electrochemical techniques have been employed to investigate and compare the changes in oxidation state and surface species of different Cu-based foam catalysts via electrochemical operation. This thesis provides valuable insights into reaction mechanisms and suggests potential strategies for further enhancing the electrochemical performance of Cu-based catalysts.

This dissertation examines the variations in bidding strategies and outcomes among different types of bidders in public takeovers, with a focus on private equity firms, public strategic buyers, and private strategic buyers. Drawing on a dataset of European public takeovers from 2005 to 2022, the study analyzes key deal characteristics, including toeholds, premium payments, irrevocable commitments, competition, hedge fund activism, and deal success rates.

The results demonstrate clear distinctions between bidder types. Strategic bidders exhibit a structural advantage over private equity bidders, as they are more likely to secure toeholds, offer higher premiums driven by synergies, and encounter less competition and hedge fund activism. Despite these advantages for strategic bidders, private equity firms achieve comparable success rates due to their extensive deal-making expertise, which allows them to negotiate effectively during the pre-offer phase.

While the differences between public and private strategic bidders are more nuanced, meaningful distinctions exist. Public strategic companies are considerably more likely to acquire toeholds before a deal announcement. In contrast, private strategic companies offset this disadvantage by offering higher premiums; however, in the absence of toeholds, the premium disparity diminishes. Notably, private strategic companies demonstrate slightly higher success rates in completing takeover attempts.

Netzwerke der Zugehörigkeit knüpfen. Konzeptionen nachbarschaftlichen Lebens in ausgewählten Stadtvierteln in Khartum und Omdurman Diese Arbeit befasst sich mit Konzeptionen von Nachbarschaft in städtischen Gebieten in Khartum und Omdurman, Sudan. Das gemeinschaftsbildende Potenzial in diesen Vierteln, ein starker Glaube an gemeinsames Handeln und die Anerkennung von und Erfahrungen mit Unterschiedlichkeit durch die Menschen, wurden während der Feldforschung zu zentralen Themen. Ziel der empirischen Studie war es, das eigene Verständnis und die Vorstellungen der Menschen von „Gemeinsamkeit" und „Zugehörigkeit" zu untersuchen. Zu diesem Zweck wurden sowohl gesellschaftliche Normen, historische Bezüge sowie kulturell-religiöse Bindungen erfasst. Aus der Vielfalt der Perspektiven ergibt sich ein Konzept der sudanesischen Nachbarschaft. Meine theoretische Auseinandersetzung mit den Begriffen Zugehörigkeit, Lokalität, Raum und Nachbarschaft stützt sich auf die Migrations-, Stadtforschungs- und Erinnerungsforschung. Die Grundannahme ist, dass sowohl der Ort als auch die sozialen Beziehungen für eine Nachbarschaft gleichermaßen wichtig sind. Die auf der Grundlage der Grounded Theory gewonnenen empirischen Ergebnisse zeigen, dass Zugehörigkeit durch soziale Prozesse entsteht, die durch lokale Praktiken gestärkt und stabilisiert werden: Gegenseitige Hilfe, Teilen, Respekt, Gleichheit und Gegenseitigkeit sind in den untersuchten Nachbarschaften besonders relevante Normen. Diese nachbarschaftlichen Praktiken haben eine starke integrative Wirkung auf dieses sozioökonomische Netzwerk mit ausgeprägten traditionellen Strukturen. Die Arbeit dokumentiert eine Reihe solcher Praktiken und beschreibt ihre Wirkung auf das Individuum. In „Sandugs" erhalten Frauen Zugang zu Kapital und damit zu unabhängiger wirtschaftlicher Tätigkeit, während gleichzeitig ein Raum für gegenseitige Beteiligung und Einflussnahme geschaffen wird. Die Prozesse der „Judiya" ermöglichen es, Familien- und Nachbarschaftskonflikte konstruktiv und schlichtend zu bearbeiten, wobei die Unabhängigkeit der Akteure betont wird. Beides ist Teil einer Identitätskonstruktion, in der Lokalität und Zugehörigkeit auf der Grundlage von Konzepten des „Sudaneseness" ausgehandelt werden. Die Menschen stellen ihr Handeln, um Stabilität und Schutz für ihre Nachbarschaft zu schaffen, in den Kontext kultureller Ideale, sie verstehen und beschreiben ihr nachbarschaftliches Verhalten als inhärent „sudanesisch". Diese traditionellen Konzeptionen von gegenseitiger nachbarschaftlicher Unterstützung und Zusammensein bilden eine starke lokale Struktur in den Nachbarschaften. Eine andere lokale Struktur ergibt sich durch die „lokalen Komitees". Sie stellen die untere Verwaltungsebene des Staates dar. Seit 2011 versuchte das Regime von Al Bashir, seine Macht und die Kontrolle über die politischen Unruhen zu erhalten, indem es die Überwachungsmaßnahmen massiv ausbaute. Dazu bediente es sich auch dieser "lokalen Ausschüsse". Seit den Aufständen von 2013 wurden jedoch parallel klandestine „Widerstandskomitees" in den Stadtvierteln gebildet, um diejenigen zu schützen, die an den Protesten teilnahmen. In den folgenden Jahren übernahmen diese Widerstandskomitees immer mehr Versorgungs- und Betreuungsaufgaben. Ihr Motto „Wir passen auf, wir kümmern uns, wir leisten Widerstand" (We watch, we care, we resist) spiegelte den sudanesischen Nachbarschaftsgeist wider, den ich während meiner zweijährigen Feldforschung von 2014-2016 beobachtet und dokumentiert habe. Während der Revolution 2019 spielten diese Nachbarschaftsnetzwerke erneut eine wichtige Rolle bei der Unterstützung des zivilen Widerstands. Im Jahr 2023 gaben sie den Anstoß zur „Revolutionären Charta zur Errichtung der Volksmacht". Schlüsselwörter: Nachbarschaft, Zugehörigkeit, Lokalität, Widerstand, Sudaneseness

Microbial communities developing on glacier and ice sheet surfaces decrease snow and ice albedo and enhance melting. The associated loss of global ice masses changes the proglacial landscapes worldwide and contribute to global sea-level rise. This is very pronounced in the Arctic, where the temperature increases four time faster than the global average. The loss of snow and ice also corresponds to an increased presence of pigmented microbial communities that bloom annually. The drivers of these blooms and the ecological relationships between the microbes inhabiting these environments, the pigmented microalgae and other microorganisms, remain misunderstood. Furthermore, snow and ice have been under-investigated as habitats supporting life, particularly regarding the ecological niches they offer through the seasonal shifts experienced in glacier ecosystems. These shifts include daily to seasonal freeze-thaw cycles, extreme light or darkness, nutrient limitations, dry conditions in winter or the abundance of liquid water in the summer. The overall diversity of such pigmented microbes and the habitat specific processes has been studied over the past decades. However, prior to my Ph.D., only sparse information was available about the ecological dynamics in supraglacial microbial communities, and their potential effects on the evolution of glacier and ice sheet surfaces under climate change are still unknown. Gaining such knowledge is crucial for the development of global models to help predict the evolution of glaciers and ice sheet biomes, and better understand their environmental implications. Additionally, quantifying changes in snow and ice habitat structure and assessing the interactions between microbial species are vital for understanding the survival strategies of microorganisms in these extreme conditions. Such knowledge can ultimately be used for astrobiological purposes, as glaciers are considered terrestrial analog systems for extraterrestrial life on cold planets and moons. To address some of the above set out questions, I combined genomic and visualization techniques and investigated the ecology of supraglacial microbial communities in the presented thesis. My work spans from the global scale, in which I assessed the biogeographical drivers shaping supraglacial microbial communities’ composition worldwide, to the single cell or mineral particle microscopic scale, where I assessed the 2D and 3D architecture of microbes and minerals on and in the ice. Specifically, in the first part, I utilized 16S, 18S and ITS rRNA gene amplicon sequencing of my own samples collected in Greenland, Iceland and Svalbard, and integrated these with data available in public repositories or shared by collaborators to create a dataset covering the Arctic, Antarctica, as well as continental glaciers worldwide. I unveiled a first global biogeographical pattern, and explored large-scale and local drivers that affect the composition and dynamics of supraglacial microbial communities. Diving deeper into the local and environmental influences, I then further investigated the specific ecological shifts in community composition, dynamics, and complexity across the snowline on the Greenland Ice Sheet by combining the genomic data from 19 supraglacial sub-habitats with their associated nutrient, ionic and carbon contents. My research revealed the existence of a global glacier core microbiome composed of both generalist and cold-specialized taxa such as Hymenobacter, Acidiphilium, Polaromonas, and Parafrigoribacterium. I showed that large-scale factors such as latitude and distance-decay partly explained microbial variability on glaciers worldwide. However, it also became clear that these were less important in defining the composition and diversity of glacier microbial communities, compared to local parameters, including sampling site, habitat, and sub-habitat. Clear ecological transitions were observed across the ever-moving snowline during the melt season on the Greenland Ice Sheet. These were characterized by an increase in bacterial diversity, dissolved organic carbon content, and a shift in community dynamics. Above and at the snowline, co-occurrence networks in white snow, red snow, and white ice showed that communities were predominantly driven by stochastic processes. In contrast, the sub-habitats below the snowline such as dark ice and black cryoconite holes exhibited more complex interactions and negative relationships, their dynamics responding to deterministic processes. A second trust of my work was focused on microscopic and tomographic analyses. I investigated the spatial and structural variations in ice core samples and assessed the influences of the ice architecture on the ecology of microbial communities. For this purpose, I studied the surface features of summer ice samples using a workflow that I developed spanning different scales of cryogenic microscopic approaches. Ice surfaces and their particulates were imaged in the field itself using a hand-held microscope. Ice patches displaying glacier ice algae were subsequently sampled, those samples preserved and transported frozen to the home-laboratory, where they were imaged with a stereoscopic microscope in a climate chamber, and a high-resolution cryo-scanning electron microscope (cryo-SEM). In addition, I employed conventional and synchrotron based cryo-computed tomography to evaluate the 3D distribution of mineral-biological aggregates and the pore structure in ice cores, collected either from below a 1.4 m snow cover or from the top bare surface ice, or weathering crust, in summer. The detailed analysis of these ice cores revealed substantial seasonal variations in ecological niches, with only a minor fraction of biological-mineral aggregates, considered as hotspots of biodiversity, having access to atmospheric inputs through the percolating channels in the winter ice. This underscores the necessity for supraglacial microorganisms to adapt to the harsh and arid conditions of the Arctic winter. This study presents a preliminary explanation for the dominance of taxa like Hymenobacter and Acidiphilium, capable of degrading organic matter under anoxic conditions, in glacier environments all over the world. Moreover, the cryo-SEM imaging highlighted the adaptive strategies of glacier ice algae communities. I could document the tendency of Ancylonema sp glacier ice algae to form chains loosely attached to ice crystal edges, an observation that suggests an evolutionary advantage for wind dispersion or enhanced photosynthetic drive. Importantly, my research highlights the existing biases in our understanding of glacier ecosystems, particularly emphasizing the disproportionate focus on the "Three Poles", while noting that continental glaciers, especially those in South America, remain significantly understudied. This discrepancy extends to the sampling of glacier habitats, where cryoconite holes have been investigated much more compared to the other sub-habitats. My thesis addresses this gap by contributing 221 new samples representing various sub-habitats from the glaciers of Svalbard and the Greenland ice sheet, thereby enriching the global sampling database. Moreover, my data underscore the critical role of sample collection and processing methods as variables that will affect amplicon sequencing outcomes, further stressing the imperative need for more standardized protocols that would facilitate better comparisons between studies and across glacier microbiomes. Overall, my work provides a new understanding about the ecology of supraglacial microbial communities, elucidating their drivers, their adaptation to the extreme conditions they thrive in, and the potential ecological shifts worldwide as glaciers melt and the bare ice area on ice sheet margins will more and more extend inland due to climate change.

To achieve membrane homeostasis, eukaryotic cells employ a complex protein machinery that orchestrates cargo flow between the Golgi apparatus, the plasma membrane and different classes of endosomes. Adaptor proteins facilitate selection, enrichment, and transport of various secretory and endocytic cargoes. Post-Golgi adaptor protein complexes (APs) as well as Golgi-localized, gamma-ear containing, ADP-ribosylation factor binding proteins (GGAs) are recruited to membranes by the small GTPase ARF1. Once on the membrane they bind cargoes and accessory factors, and according to classical models, drive the formation of small clathrin-coated vesicular transport intermediates to promote bidirectional transport between the Golgi and endosomes. The recent discovery of tubular, ARF1-positve transport intermediates decorated by clathrin, made us rethink the classical long-range vesicular model and brought us to investigate the function of these compartments in post-Golgi trafficking. In this work, I re-evaluated the localization and the function of different post-Golgi adaptor proteins in the context of tubular ARF1-transport intermediates. By combining CRISPR-Cas9 gene editing with interactome mapping and advanced imaging techniques, including live-cell confocal and stimulated emission depletion (STED) microscopy as well as correlative lightelectron microscopy, I discovered that ARF1 compartments are a novel class of tubulovesicular endosomal compartments. Importantly, the majority of non-endocytic clathrin and different adaptors including AP-1, AP-3 and GGAs localize to segregated nanodomains on ARF1 compartments. Settling a debate in the field, I observed that clathrin is only recruited to AP-1- but not AP-3-nanodomains. AP-1-nanodomains are found at the interface of ARF1 compartments and recycling endosomes and AP-1 knock-out (KO) causes the formation of long aberrant tubules possessing the identity of both compartments and disrupts cargo flow. These findings suggest that AP-1 mediates short-range transport from ARF1 compartments to recycling endosomes, possibly via a kiss-and-run mechanism rather than promoting longrange vesicular transport. Furthermore, I observe transient interaction of AP-1- and GGAnanodomains on ARF1 compartments and interactome analysis shows that AP-1 binds most of its cargoes only in the absence of GGAs. Thus, GGAs could act as switch in AP-1-mediated cargo sorting by regulating cargo-AP-1 interaction. Taken together, in this work I re-envision the mechanisms of adaptor-mediated cargo-transport and expand our understanding of how proteins are transferred between organelles. AP-1mediated cargo hand-over from newly described ARF1 compartments to recycling endosomes, redefines the role for AP-1 in post-Golgi transport. My data and recent literature suggest that post-Golgi communication occurs via transient interactions between compartments of a tubulovesicular endosomal network. In addition, I present an alternative model for the role of GGAs in AP-1-mediated protein sorting, where GGAs control which cargoes are sorted by AP-1.

The use of fossil based energy sources over the last two centuries has played a huge role in the upliftment of human society. Per-capita energy consumption and population have both been sharply increasing, leading to an ever increasing demand for energy. The current reliance on fossil-based energy has come at the expense of our environment as is seen by the rising CO2 greenhouse gas levels, which pose a threat to society as we know it. Curbing CO2 emissions by closing the anthropogenic carbon cycle and electrifying processes that release CO2 and other greenhouse gases is going to be essential going forward. Recent technological and engineering advancements have led to alternative non-fossil based renewable energy sources that are sustainable, cyclical and do not create an imbalance in the existing natural carbon cycles. Using these renewable energy sources (electrifying) to power the transportation and industrial sectors besides just being a primary energy source is also crucial to remove dependence on fossil-based energy.

Electrochemical CO2 conversion to produce hydrocarbons is a CO2 negative approach that provides alternative pathways to synthesize chemicals and energy dense fuels, essential for both industry and society. As this approach relies only on electrical power, it is an important field of research that could be a cornerstone of a fully electric grid of the future. The ability to access/synthesize chemicals and fuels with the primary energy input being renewable electricity could help decarbonize the chemical sector. While a promising technology, this approach still has to overcome some technological hurdles to reach industrial applicability. Increasing the scale, stability and selectivity whilst overcoming energy losses is the main scientific challenge. We conducted a study to benchmark three different carbon conversion approaches across various performance and operational parameters. We compared plasma based approaches and two electrochemical approaches, high-temperature (HT) electrolysis and low-temperature (LT) electrolysis. Our bench-marking study indicated to us that whilst HT-electrolysis was the most power efficient approach to synthesize CO from CO2 its inability to access larger hydrocarbons made LT-electrolysis a more viable approach for such compounds.

While initial research in the LT-electrolysis field focused on catalyst development recent studies have highlighted the crucial role of the catalytic microenvironment on the performance of electrochemical cells. In this thesis we mainly investigate the role of different microenvironment constituents on the performance of electrolysers operated with commercial Cu catalysts. These micro-environmental parameters were investigated for electrochemical approaches to convert both CO2 and CO to value added C2+ products. The initial part of the work focused on understanding the impact of electrolyte ions on the performance (stability, activity) of CO2 electrolysers. Here we were able to highlight the role of unintended cation crossover from the anode to the cathode. Lowering electrolyte ion concentration (anolyte) led to lower cation concentration and a change in the selectivity of zero-gap gas diffusion electrode (GDE) CO2 electrolysers. It was observed that for lower electrolyte concentrations the primary product formed was carbon monoxide (CO) as opposed to ethylene C2H4, which was predominantly formed at higher electrolyte concentrations. These electrolyte concentration studies were then replicated for two other electrolyser configurations (catholyte-flow GDEs and H-cells), where it was found that the different electrolysers were impacted differently on changing the electrolyte concentration. The catholyte-flow electrolysers showed a lesser impact of electrolyte concentration on product selectivity.

Next, we evaluated the impact of ionomers on the performance of CO2 electrolysers by systematically varying the ionomer amount in the catalyst layer. Ionomers are typically used for their role as binders and also ion conducting species. Through our experiment in the catholyte-flow GDE electrolysers it was observed that incorporation of an ionomer (Nafion) led to drastic shift in selectivity from C2H4 to CO. On the incorporation of Nafion we were able to selectively reduce CO2 to CO on copper (Cu) based catholyte-flow GDEs with faradaic efficiencies (FE) reaching upto 90\%. These experiments were also repeated for two other electrolyser configurations and here as well a dependence on the electrolyser configuration was found.

To assess if CO2 and CO behaved similarly, we conducted experiments with replicate Cu GDEs and it was observed that to facilitate meaningful CO reduction currents, an ionomer was crucial. We hypothesize that this is due to the vastly lower solubility of CO in aqueous solutions in comparison to CO2.This result highlighted the necessity of ionomers for CO reduction and was a crucial milestone for further CO reduction studies.

Besides altering the catalytic microenvironment, we also wanted assess the impact of a second element (Sn/In) on the behaviour of Cu catalysts. A composition dependent selectivity trend was observed where for Cu rich catalysts (low Sn or In amounts) predominantly CO was formed and on increasing the amount of Sn/In the selectivity switched towards formate indicating synergistic effects in bimetallic catalyst systems.

Over the course of this work we highlighted crucial interfacial microenvironment parameters that affected the behaviour of Cu based electrolysers for both electrochemical CO2and CO conversion. Having gained a better insight into the interfacial parameters affecting the electrolyser performance the future challenges are to incorporate non Cu based catalysts that are more selective towards a given product.

Photo-excited nanodiamonds can efficiently emit electrons due to their negative electron affinity, making them promising candidates for photoinduced electron injection into liquid water. The emitted electron can become solvated, enabling high-energy redox reactions. This study investigates the initial photoexcitation and charge-transfer dynamics using adamantane–water clusters as a model system. The charge-transfer mechanism involves excitons, which feature HOMO-to-LUMO transitions from adamantane to water. Water structures with disrupted hydrogen bonding and large dipole moments stabilize the photoexcited electron. Similar charge-transfer process in bulk water is confirmed through molecular dynamics and LR-TDDFT simulations. The exciton properties are benchmarked using DFT, LR-TDDFT, and many-body perturbation theory (GW/BSE). Amino functionalization of adamantane is further explored as a promising material design strategy to reduce the energy gap of adamantane and enhance charge transfer. Nevertheless, excessive modification can reduce electron emission. Overall, this work clarifies how nanodiamond surface properties govern photoexcitation-driven charge transfer and electron solvation in liquid water.

Copy number variation (CNV) refers to the variation in the number of copies of a DNA segment in the genome, which can influence regions of one or a few genes up to a whole chromosome. CNVs which provide cells with survival and growth advantages are retained through natural selection and are frequently observed across various types or subtypes of cancer. These CNVs can serve as important clinical biomarkers for cancer stratification.

Different techniques, including karyotyping, fluorescence in situ hybridization, array comparative genomic hybridization, single nucleotide polymorphism array, and next-generation sequencing, have been used to characterize CNV profiles. The resolution of CNV detection has increased from chromosomal-level in karyotyping to kilobase pair level in next-generation sequencing. CNV biomarkers are identified after analyzing samples of the same cancer type or subtype. The identified CNV biomarkers reciprocally provide advanced guidelines of cancer classification, enhance the diagnostic accuracy, and improve treatment of patients.

However, the application of these CNV biomarkers to rapid, particularly intraoperative, tumor assessments within the timeframe of neurosurgical procedures has remained elusive due to the protracted duration of conventional CNV characterization methods. The recent development of nanopore sequencing has enabled the real-time interpretation of the nucleotides and methylation status of DNA and RNA molecules. However, it is still a challenge to obtain the real-time CNV profiles that can improve diagnosis and treatment decisions in the operating room due to the lack of sensitive and reliable CNV detections.

In this thesis, we propose a statistical framework, called CNVisor, designed for rapid CNV detection from nanopore sequencing within one hour of biopsy to provide accurate CNV profiles and reliable CNV ranges, informing critical intraoperative decisions. The proposed method is applied to eight brain tumor patients during surgery and can enhance the current real-time glioma classifier based on methylation profiles. Moreover, CNVisor's compatibility with low sequencing coverage can facilitate non-invasive and precise cancer diagnostics through the CNV analysis of liquid biopsies from cerebrospinal fluid where only limited amount of DNA can be obtained. CNVs are also frequently observed in induced pluripotent stem cells (iPSCs) . We utilize the proposed method to evaluate the genome integrity of iPSCs obtained from the fibroblasts of northern white rhinos (\Ceratotherium simum cottoni), in which the iPSCs will be used for in vitro gametogenesis, i.e., an assisted reproductive technology with the potential to rescue this functionally extinct species.

We address the following geometric question: for a given \( d \geq 1 \) and a given \( k \geq 1 \), what is the smallest number \( N \) such that there exists a continuous map \( f \colon \mathbb R^d \to \mathbb R^N \) with the property that, for any points \( (x_1, \ldots, x_k) \in \mathbb R^d \) their images \( (f(x_1), \ldots, f(x_k)) \in \mathbb R^N \) are linearly independent? A map satisfying this condition is known as \emph{\( k \)-regular}. Naturally, one can pose an analogous question for the case where the target space is \( \mathbb C^N \) and the images are \( \mathbb C \)-linearly independent.

This question appeared in the work of Karol Borsuk in the 1950s. In the 1970s, Frederick R. Cohen and David Handel translated the problem of finding lower bounds for \( N \) into a question about the (non-)existence of vector bundles over the \emph{space of \( k \) distinct points in \( \mathbb R^d \)}, thereby initiating the use of algebraic topology to tackle the problem. This approach has since been developed by various authors. In this thesis, we also work on the side of algebraic topology to improve the existing lower bounds for $N$.

More specifically, in this thesis, we are working to show that certain real or complex vector bundles must necessarily be of rank at least $N-k$. This achieved by demonstrating that the largest index of a non-zero characteristic class - Stiefel--Whitney in the real case and reduced mod-$p$ Chern in the complex case - must be at least $N-k$. To be able to reason about these characteristic classes, in Section 2, we study in detail the cohomology rings in which they reside. Then in Section 3 we review the constructions of the vector bundles that we would like to study and review known results about their characteristic classes. In Section 4, we describe potential approaches for obtaining the lower bounds and provide several computations that improve upon existing results.

Lastly, to facilitate our computations, we make certain simplifications by transitioning to a more tractable cohomology ring. A natural question arises: is there potential to obtain even better bounds by working in the original ring? We provide a partial answer to this question in Section 5. By employing an approach existing in the literature for working in characteristic 2, we show in Section 5 that, when the characteristic is odd and \( d \) is odd, the map of cohomology rings is injective. Consequently, the transition to a simpler ring in these cases still produces the best bounds that can be achieved using the method of Cohen and Handel.

Hintergrund: Angesichts der wachsenden und zunehmend diversen Bevölkerungsgruppe in unserer Gesellschaft, die am Lebensende eine hospizliche und palliative Versorgung benötigt, besteht ein wachsender Bedarf an Wissen zu den damit verbundenen Übergängen. Verfügbare Studien zu Fragen des Übergangs liegen überwiegend aus westlich geprägten Staaten vor, in denen es – bei aller individueller Variabilität – eine breit geteilte Auffassung von Palliative Care gibt. Trotz allem muss davon ausgegangen werden, dass sich die Ergebnisse und Erfahrungen der Forschung aus anderen Ländern aufgrund der teils sehr unterschiedlichen Versorgungsstrukturen bzw. Gesundheitssysteme nur begrenzt auf die Situation in Deutschland übertragen lassen. Zudem ist offen, welche Rolle soziale und kulturelle Dimensionen im Übergang in die Hospiz- und Palliativversorgung bzw. bei der Inanspruchnahme von Versorgungsangeboten am Lebensende für Menschen mit und ohne Migrationshintergrund spielen, insbesondere fehlen Erkenntnisse zu den Erfahrungen von Betroffenen und Mitarbeiter:innen aus den unterschiedlichen Settings der Hospiz- und Palliativversorgung. Methode: Den theoretischen Rahmen für die qualitative Untersuchung bilden die subjektorientierte Übergangsforschung und das Konzept der sozialen Repräsentationen. Für eine möglichst umfassende Sicht auf Übergänge am Lebensende im Kontext der Hospiz- und Palliativversorgung werden unterschiedliche Settings der Versorgung und Perspektiven der beteiligten Akteur:innen in die Untersuchung einbezogen. Das episodische und das Expert:inneninterview werden als Methoden der Datenerhebung trianguliert. Die Datengrundlage bilden 22 episodische Interviews mit Patient:innen sowie An- und Zugehörigen mit und ohne Migrationshintergrund sowie 20 Expert:inneninterviews mit Mitarbeiter:innen unterschiedlicher Berufsgruppen. Die Daten wurden mit dem Ziel einer fall- und fallgruppenübergreifenden Analyse von Deutungs- und Handlungsmustern thematisch kodierend analysiert. Ergebnisse: Der Übergang in die Hospiz- und Palliativversorgung ist ein Prozess, der durch Phasen der Liminalität (Pause vor dem letzten Akt und des Angekommenseins) sowie des Vertrautwerdens mit der Bühne des letzten Akts strukturiert ist, der für die An- und Zugehörigen sowie für die Mitarbeiter:innen mit dem Tod der Patient:innen endet. Dieser Prozess ist einbettet in ein komplexes Bedingungsgefüge, in den Ärzte und Ärzt:innen, Koordinator:innen an den Schnittstellen der Versorgung sowie Pflegekräfte in den Netzwerken der HPV als Gatekeeper sowie Zu- und Angehörige als sogenannte Sozialisationshelfer:innen eingebunden und bedeutsam sind. Auf Basis dieser Ergebnisse wurden Thesen entwickelt, die die unterschiedlichen Perspektiven der Untersuchung aufgreifen und die Vielschichtigkeit bestimmter Phänomene im Übergangsprozess in ihrer Konsequenz verdeutlichen. Dazu gehören unter anderem Umgangsweisen der Mitarbeiter:innen mit herausfordernden Situationen, Formen der pflegerischen Begleitung durch die An- und Zugehörigen sowie die Bedeutung des Hospizes als Sterbeort als Option für die Patient:innen. Dabei werden relevante Unterschiede und Gemeinsamkeiten im Hinblick auf einen Migrationshintergrund der Patient:innen sowie der An- und Zugehörigen aufgezeigt, die auf die Heterogenität der russischsprachigen Migrant:innen verweisen, aus der sich zum einen Gemeinsamkeiten mit Personen ohne einen Migrationshintergrund in den Vorstellungen zu einem Übergang in die HPV, zum Beispiel im Hinblick auf die Vereinbarkeit von Sterbebegleitung, familiärer Sorgearbeit und Erwerbsarbeit, zeigen. Zum anderen werden Unterschiede im Hinblick auf eine bedürfnisorientierte Versorgung deutlich, die für Menschen mit Migrationshintergrund unter anderem aufgrund von Sprachbarrieren beeinträchtigt sein kann. Abschließend wird veranschaulicht, dass die Begegnungen der unterschiedlichen Akteur:innen im Prozess des Übergangs in einem Spannungsfeld zwischen einem Aushalten und einem Haltgeben durch die beteiligten Akteur:innen geprägt sind. Diskussion: Die vorliegende Untersuchung verdeutlicht, dass der Übergangsprozess an seinen Schnittstellen, hier als „Breaking points“ bezeichnet, maßgeblich von den sich begegnenden Akteur:innen und ihren jeweiligen Vorstellungen für den weiteren Verlauf abhängen. Dabei zeigt sich für den Kontext der Hospiz- und Palliativversorgung, dass konzeptionelle Überlegungen zu „Palliative Care“ und „Hospiz“ nicht immer das passende Skript für die Gestaltung der Versorgung in der Praxis darstellen. Die sich zeigenden Sollbruchstellen werden in der Praxis entlang der sich zeigenden Vorstellungen der Patient:innen sowie der An- und Zugehörigen weitgehend überwunden. Sich in diesen Zusammenhängen zeigende Variationen von Verläufen im Übergangsprozess sollten Eingang in weitere konzeptionelle theoretische Überlegungen finden, beispielsweise im Hinblick auf Entscheidungsfindungen im Prozess. Implikationen für weitere Forschung zeigen sich unter anderem zur Bedeutung der „unit of care“ von Patient:innen sowie Zu- und Angehörigen, um beispielsweise Veränderungsprozesse im Hinblick auf das Verständnis von familiärer Sorge am Lebensende zu untersuchen und die damit einhergehenden vielfältigen Bedürfnisse für die Praxis sichtbar zu machen. Darüber hinaus ist nach wie vor offen, wie eine frühe Integration der HPV in die Versorgung von schwerkranken und sterbenden Patient:innen gelingen kann. Dabei sollten stärker die Möglichkeiten für eine informierte Vorbereitung als auf eine dezidierte Vorausplanung des letzten Akts des Lebens gesetzt werden.

Die ED stellt einen Komplex verschiedener entwicklungsbedingter Gelenkpathologien dar, die einzeln oder in Kombination auftreten können, und nicht jedem dysplastischen Gelenk liegt dasselbe Erkrankungsmuster zugrunde. Die Biomechanik dysplastischer Gelenke ist unvollständig geklärt, aber es konnte bereits gezeigt werden, dass erkrankte Gelenke Veränderungen in der intraartikulären Kontaktmechanik und Kraftübertragung aufweisen. Infolgedessen gestaltet sich die Entscheidungsfindung in Bezug auf die Therapie dieses Krankheitskomplexes schwierig und die derzeit verfügbaren chirurgischen Interventionsmöglichkeiten liefern variierende Ergebnisse mit z. T. hohen Komplikationsraten. Um die für den jeweiligen Patienten wirksamste Therapie ermitteln zu können, wäre es von Vorteil, die individuelle Gelenkmechanik des Patienten im erkrankten Zustand (Ist-Zustand) reproduzieren und charakterisieren zu können sowie eine Vorhersage über die Gelenkmechanik nach einem operativen Eingriff (Soll-Zustand) machen zu können. Neben computergestützten Simulationen stellen biomechanische Testungen an synthetischen patientenspezifischen Gelenkreplikaten als Ersatz für das native Gelenk eine nicht invasive Möglichkeit zur Erfassung und Quantifizierung der individuellen Gelenkmechanik dar.

Ziel dieser Pilotstudie war die Validierung 3D-gedruckter Gelenkreplikate als Ersatz für das äquivalente native Ellbogengelenk in Bezug auf intraartikuläre Kontaktflächen der humeroulnaren Artikulation. Zur Erfassung und anschließenden Quantifizierung intraartikulärer Kontaktareale wurden biomechanische Belastungsversuche unter Anwendung einer Abdruck-Technik an Ellbogengelenken kaniner Kadaver sowie an den entsprechenden 3D-gedruckten Gelenkreplikaten durchgeführt. Es wurden Silikonabdrücke generiert unter der Annahme, dass in Bereichen, an denen die humero-ulnaren Gelenkflächen Kontakt haben, Silikonmasse weggedrückt wird und somit silikonfreie Areale, also Kontaktareale, entstehen und in Bereichen fehlenden Kontaktes kein Silikon weggedrückt wird. Die Testungen wurden an drei Kadavergelenken und drei synthetischen Gelenkreplikaten, die mittels SLA-Druck aus Kunstharz gefertigt worden waren, durchgeführt. Die im 90° Winkel in eine Materialprüfmaschine eingespannten Präparate wurden jeweils mit 50 N, 100 N und 200 N belastet. Die Kontaktmuster wurden nacheinander mithilfe eines Kontrastmittel-Deckfarben-Gemisches auf die jeweilige ulnare Gelenkfläche transferiert und die Knochen- bzw. Plastikmodelle mit den jeweils transferierten Kontaktmuster mittels CT digitalisiert. Anhand der CT-Daten wurden digitale 3D-Rekonstruktionen generiert. Im Gegensatz zu den Knochenkontakten, die eine klare Abgrenzung zwischen Kontakt (kein Silikon) und fehlendem Kontakt (Silikonschicht) zeigten, wiesen die Plastikkontakte aufgrund der fehlenden, für Knorpel typischen viskoelastischen Eigenschaften ein zentrales freies Silikonareal und eine Ausdünnung des Silikons in Form einer dünnhäutigen Silikonmembran in der Peripherie der Kontaktareale auf. Die Plastikkontakte wurden deshalb zweifach validiert, indem der ursprüngliche Plastikkontakt als auch der Plastikkontakt nach Abtragen der dünnhäutigen Silikonmembran (nachbearbeiteter Plastikkontakt) ausgewertet wurde. Um die Kontaktmuster von Knochenmodell und Plastikmodell quantitativ vergleichend beurteilend zu können, wurden die digitalisierten Knochen- bzw. Plastikkontakte extrahiert und auf die ulnare Gelenkfläche (Referenzgelenkfläche) der digitalen 3D-Rekonstruktion des nativen Knochenmodells (STL-Modell), das für die jeweilige Versuchsreihe als Vorlage für den 3D-Druck diente, projiziert. Das dazu erforderliche Alignment der jeweiligen In-silico-Modelle erfolgte mithilfe von 3D-Registrierungstechniken. Anschließend wurden die auf die Referenzgelenkfläche projizierten Kontaktmuster mithilfe eines eigens dafür geschriebenen Python-Skripts in die Referenzgelenkfläche integriert und zu einem digitalen Objekt vereint. Die Kontaktmuster wurden visuell beurteilt und quantitativ ausgewertet.

Allen Knochen- und Plastikgelenken gemein waren Kontaktbereiche am Proc. anconeus sowie am medialen Koronoid, die sich mit steigender Belastung ausdehnten und konfluierten. Mit zunehmender Last erfolgte eine Größenzunahme der Knochen- und Plastikkontakte, wobei die Größe der Kontaktfläche am Plastikmodell stets kleiner war als am Knochenmodell. Als Maß für die Übereinstimmung der Kontaktmuster wurden folgende Scores berechnet: Sørensen-Dice-Koeffizient und ein Contact-Patch-Agreement-Score, die neben der Größe auch die Topografie der Kontaktareale berücksichtigen, Intraklass-Korrelationskoeffizient sowie ein Single-Observer-Score. Alle Scores fielen für die überarbeiteten Plastikkontakte stets höher aus als für die ursprünglichen Plastikkontakte, was auf eine bessere Übereinstimmung zwischen überarbeiteten Plastikkontakten und Knochenkontakten schließen lässt. Bei den überarbeiteten Plastikkontakten konnte zudem eine stete Zunahme der Score-Werte von ICC [0,54 (50 N); 0,69 (100 N); 0,71 (200 N)], Sørensen-Dice-Koeffizient [0,49 (50 N); 0,68 (100 N); 0,72 (200 N)] und Single-Observer-Score [5,7 (50 N); 6,7 (100 N); 7,5 (200 N)] mit steigender Belastung festgestellt werden, was für eine zunehmend bessere Übereinstimmung von Knochen- und Plastikkontakt mit Lastzunahme spricht. Von allen Scores wies der Agreement-Score bei allen Belastungsstufen die beste Übereinstimmung zwischen Knochen- und Plastikkontakten auf und liegt für die überarbeiteten Plastikkontakte bei 0,65 (50 N), 0,77 (100 N) und 0,76 (200 N).

Zusammenfassend lässt sich sagen, dass 3D-gedruckte Gelenkreplikate des kaninen Ellbogengelenks in der Lage sind die Topografie der intraartikulären Kontaktareale analog zum Originalgelenk abzubilden, wobei die Plastikkontakte kleiner ausfallen als die Knochenkontakte. Zur exakteren Replikation von Kontaktmustern an synthetischen Gelenkmodellen sind weitere Studien erforderlich, die den Einsatz anderer Segmentationstechniken und Druckmaterialien bzw. 3D-Druckverfahren evaluieren und eine Optimierung des Surface-Finish anstreben.

Die vorliegende Dissertation untersucht mittels eines ontologischen und kontextuellen Ansatzes die mesopotamischen Darstellungen von Menschen und ihrer Sozialkörper auf Bildwerken der Frühdynastischen und Akkad-Zeit. Der Sozialkörper umfasst hierbei den menschlichen Körper mitsamt sämtlichen Modifikationen und sozialen Überformungen, welche durch Quellen der visuellen Kultur überliefert sind. Ausgehend von dem Hintergrund einer heterarchischen Sozialstruktur mesopotamischer Gesellschaften und der Analyse der mesopotamischen Ontologie sind die Darstellungen systematisch nach soziokulturellen, politischen und ontologischen Aspekten untersucht worden. Hierfür wurde ein umfangreiches Bildkorpus zusammengestellt, welches alle gängigen Bildmedien der untersuchten Epochen miteinbezieht. Die mesopotamische Ontologie konnte anhand des Aufbaus der Sozialkörperdarstellungen und verschiedener philologischer Quellen als Analogismus (nach Descola 2013) identifiziert werden. Damit war es möglich, die ikonographisch und teils materiell kompositen Darstellungen von Sozialkörpern mit dem kompositen Personenkonzept in einem kohärenten Modell zu vereinen. Dieses erklärt nicht nur die Verbindung zwischen Bild (alan / ṣalmum) und Person, obwohl beide gleichzeitig verschiedene Entitäten sind, sondern auch z. B. die Rolle der me als Essenzen, die als Bestandteile in Entitäten und verschiedenen Objekten manifestiert sein können. Zu letzteren gehören u. a. auch bestimmte Gewänder, Kopfbedeckungen oder Frisuren. Das Bildkorpus von Menschendarstellungen wurde sowohl anhand von Typologien der Einzelelemente als auch ihrer Kombination in Sozialkörpertypen erschlossen. Anhand dieser konnte das Aufkommen einzelner Elemente als auch der Sozialkörpertypen nach Titeln, Berufsgruppen, Handlungsfeldern und sozialem Status analysiert werden. Der Befund zeigt, dass viele Gruppen unterschiedliche Sozialkörpertypen umfassen können und somit unterschiedliche soziale Ränge ausdrücken. So zeigt auch der Textbefund, dass z. B. Beamt:innen in größeren Tempeln einen anderen sozialen Rang als diejenigen kleinerer Heiligtümer innehatten, auch wenn sie dieselben Titel trugen. Diese Befunde verweisen auf eine heterarchische Sozialstruktur mesopotamischer Gesellschaften, die auf einem Beziehungsgeflecht aus verschiedenen Groß- (Tempel, Palast, Eliten) und Kleinhaushalten basierte. Damit verbunden sind auch verschiedene Szenentypen, wie die Bankettszenen, nicht primär „kultisch“ (u. a. heilige Hochzeit, Tempelfeste) zu deuten, sondern zeigen das gemeinsame Trinken (Kommensalität) als einen zentralen Handlungsraum für Mikropolitik, indem sie idealisierte Haushalte, ihre verschiedenen Grade an sozialer Differenzierung und diakritische Elemente darstellen. In den Bildern sind keine fixierten Ikonographien von Herrschern oder anderen Personengruppen auszumachen. Die Variabilität der Sozialkörper resultiert neben regionalen und diachronen Unterschieden aus einer aktiven Konstruktion, die bewusst Differenzierungen und Ambivalenzen einsetzt. Über bestimmte Elemente (z. B. Gewänder, Frisuren, Kopfbedeckungen) können Analogien zwischen Menschen und anderen Entitäten (Gottheiten, Helden) konstruiert werden, welche zeigen, dass man die Grenzen zwischen ihnen nicht kategorisch zog, sondern dass alle Entitäten in einem kontinuierlichen Kosmos graduell voneinander differenziert wurden. Damit ist es möglich, dass z. B. Herrscher und Priester:innen sich dem Göttlichen über bestimmte Elemente, die auch bei Gottheiten auftreten, annähern konnten. Die vorliegende Arbeit untersucht, wie Bilder ihren ontologischen und soziopolitischen Rahmen nutzen und manipulieren, um neuen Sinn und eigene Realitäten zu erschaffen. Sie beleuchtet den Analogismus mesopotamischer Prägung und die essenzlogischen Verbindungen zwischen Entitäten anhand der Darstellungen menschlicher Sozialkörper. In einer detaillierten Auseinandersetzung mit den Konstruktionen von Sozialkörpern wurden verschiedenste Aspekte wie sozialer Rang/Status, Gender (graduell abgestufte Formen von Maskulinitäten und Femininitäten, non-binäre Genderkategorien), regionale Unterschiede, diachroner Wandel, kulturelle Stereotypisierungen oder Materialität der Bildträger anhand der Darstellungen von Herrschern, verschiedenen Priester:innen, Tempelverwaltern, Beamt:innen, Schreiber:innen, Menschen in Bankett- und Verehrungsszenen, Musikant:innen, Bauern, Hirten, Fischern, Sklav:innen, Gefangenen, Feinden und anderen unter Einbeziehung ihres soziokulturellen Kontexts tiefergehend analysiert.

Katastrophenvorsorge ist unerlässlich, um Leben zu retten, Schäden zu begrenzen und wirtschaftliche Stabilität in Krisenzeiten zu sichern. Diese Arbeit fokussiert sich auf die Entwicklung eines resilienten, dezentralen IT-System (Informationstechnologie-System), welche die Vernetzung und Koordination zwischen den vielfältigen Akteuren im Katastrophenschutz erheblich verbessert. Während derzeit Informationen oft mühsam manuell gesammelt werden, ermöglicht diese Architektur einen effizienten, digitalen Austausch, der die Zusammenarbeit zwischen Einsatzkräften, Behörden und der Bevölkerung optimiert. Durch umfassende Anforderungsanalysen und die Anwendung moderner Entwicklungsmethoden wurde eine flexible Softwarearchitektur entworfen, die sich als Anwendungsfall zu Evaluierung des Systems auf die Koordination spontaner Freiwilligeneinsätze spezialisiert. Die Lösung umfasst ein webbasiertes Dashboard und mobile Apps, welche in einem realistischen Szenario getestet wurden. Die Ergebnisse zeigen eine hohe Akzeptanz und Zufriedenheit unter den Nutzenden, was die praktische Anwendbarkeit und den Nutzen des Systems unterstreicht. Dieses System bietet ein Modell, das auf verschiedene Szenarien und Stakeholder angepasst werden kann.

Iron-carbon interactions in soils play a crucial role in global carbon cycles, especially in the (sub-)Arctic regions, which are experiencing significant hydrological changes due to climate warming. In Iceland, such soils are exposed to seasonal water table fluctuations. The soils are derived from intense weathering of basaltic rocks, which contain high iron content. Upon seasonal waterlogging, these soils react and form short-range ordered (SRO) iron (oxyhydr)oxides and crystalline iron carbonates (siderite). These two iron phases have been suggested as potential sinks for the prevalent dissolved organic carbon (OC) and dissolved inorganic carbon (DIC), respectively. However, prior to my PhD work, very little was known about the fate of SRO iron (oxyhydr)oxides and their role in OC cycling under dynamic geochemical conditions, such as seasonal waterlogging. Similarly, although siderite has been assumed to be vulnerable to oxidation, the mechanisms behind its formation and its stability under varying redox changes were not well understood. To bridge these knowledge gaps, I conducted a comprehensive study that first targeted field observations and the detailed characterization of Icelandic soils. The prime redox horizon in these soils was used for microcosm experiments where seasonal waterlogging was mimicked experimentally, and solutions and solids were analysed as a function of time. Finally, at the most detailed scale, I used complex laboratory and synchrotron-based analyses to examine the interaction between iron nanoparticles and carbon moieties to assess the molecular-level processes. Through field characterization of Icelandic soil horizons (oxic, anoxic, redox-fluctuating), I demonstrated that redox fluctuations significantly influence the protection of OC by SRO iron (oxyhydr)oxides, particularly in highly weathered horizons. Sequential iron extraction and spectroscopic analyses demonstrated that SRO iron (oxyhydr)oxides, abundant in redoxfluctuating horizons (90.9 mg g⁻¹), initially stabilize OC. However, these iron phases were prone to reductive dissolution, which released the initially stabilized carbon. Despite the presence of reactive SRO iron phases, OC depletion occurred due to oxidative depolymerization of complex biomolecules into low-molecular-weight (LMW) OC. This, in turn, was easily degraded by microbes, as documented via 16S rRNA sequencing work. Under fluctuating water table conditions, this change in OC behaviour was also accompanied by losses in silica (Si), aluminum (Al) and phosphorus (P). However, only 2 wt.% of the total soil carbon was lost in the dynamic redox-zone, while the remainder could be attributed to the formation of siderite which accounted for 56% of the total iron in the redox horizon. To elucidate the conditions favorable for siderite formation and the mechanisms behind its stabilization, I combined chemical, mineralogical, and microbiological characterization and could show that siderite did not form through direct precipitation but rather through the bioreduction of SRO iron phases, coupled with microbial OC utilization. Specifically, under reducing condition, large quantities of SRO iron oxides served as precursors that provided the needed Fe2+ and was accompanied by a significant OC depletion in the redox-active horizont. 16S rRNA analysis identified a previously under-studied iron-reducing bacterium, Candidate Sva0485, as thriving in the anoxic zone. To experimentally investigate how and why siderite persisted in the redox horizon, I conducted redox-cycling incubation experiments in which I monitored the mineralogical and geochemical transformations. My results demonstrated that siderite remained stable throughout multiple redox cycles. These findings underscore the potential of siderite as a stable inorganic carbon reservoir, especially under dynamic environmental conditions. Finally, I experimentally investigated what controlled the observed carbon loss from the SRO phases, by following the interactions between an organic phosphate (OP) and a synthetic SRO ferrihydrite. By combining conventional laboratory and synchrotron-based X-ray absorption spectroscopy (XAS) methods, I was able to reveal that OP disrupted Fe(III) polymerization, reducing the ferrihydrite surface area from 300 to 3 m2 g-1 and shifting Fe–P pair bonding from a bidentate binuclear (2C) to a monodentate mononuclear (1V) geometry. Under reducing conditions, the decrease in size of the formed ferrihydrite units enhanced both the organic phosphate and the iron mobility. These findings have important implications for nutrient cycling in Arctic soils experiencing frequent hydrological shifts. In summary, through my doctoral research, I advanced our understanding of iron-carbon dynamics in Icelandic soils that change fast under climatic change. These findings emphasize the vulnerability of iron-organic carbon associations to climatic hydrologic shifts, while highlighting the potential of siderite as a stable inorganic carbon reservoir for climate mitigation strategies in basaltic soils. The research also has broader implications for estimating carbon stocks and greenhouse gas emissions in the (sub-)Arctic regions.

Climate is an important modulator of erosion, which, in combination with tectonic uplift, shapes the surface of the Earth. In cold regions, landscape evolution is dominated by processes associated with the presence or absence of ice. One process, “frost-cracking,” has been shown to be a particularly efficient means of weathering rock, though the link between frost-cracking and erosion is not well-constrained, particularly for the cold, bedrock hillslopes which characterise high-alpine regions. This thesis evaluates the sensitivity of bedrock hillslope erosion rates to temperature using a suite of novel geochemical proxies: combined in-situ He-3, C-14, and Be-10 in quartz. The first scientific study presents results from a 1D numerical model of in-situ cosmogenic Be-10, C-14, and He-3 concentrations, which is used to explore the suitability of these three proxies for quantifying erosion rates in areas undergoing non-steady state erosion. The results from this work suggest that even in stochastically eroding settings, Be-10-derived erosion rates of amalgamated samples can be used to estimate long-term erosion rates; that infrequent large events can lead to bias, which can be identified using C-14; and that the concentration of He-3 relative to that of Be-10, and the palaeothermometric interpretations derived from it, are unaffected by erosional stochasticity. The second scientific study builds off the theoretical considerations presented in the previous chapter and tests the feasibility of actually employing the Be-10-C-14-He-3 system at the Aiguille du Midi in the central Mont Blanc massif. The results presented herein do not suggest a correlation between frost-cracking and erosion rates, with relatively high frost-cracking rates occurring in both rapidly and slowly-eroding surfaces, suggesting that other mechanisms must be responsible for the eventual evacuation of material from the hillslope. The final chapter expands the theoretical work of the modelling and initial field study to sites across the European Alps, wherein 27 new hillslope erosion rates are presented, inferred from cosmogenic nuclide concentrations in samples collected from bedrock hillslopes of varying lithology, hillslope angle, hillslope aspect, elevation, and relief. Results from this work suggest that bedrock temperature alone is not the rate-limiting factor setting erosion rates in these hillslopes, in contrast to previous studies suggesting that frost-cracking dictates rates of erosion in bedrock hillslope landscapes. A final summarising assessment is provided, as well as an outline for future work.

This dissertation is a biography of Meir Poppers (1628-1662), a traveling kabbalist of the seventeenth century. Through a study of Poppers’ life and writings, I show how Lurianic kabbalah – the most influential form of Jewish esoteric knowledge since the early modern period – circulated in manuscripts between Ottoman Palestine and East-Central Europe. In five chapters, I reconstruct Poppers’ initial travels from his birthplace of Kraków to Jerusalem to study kabbalah. I show how his economic and cultural contexts shaped his intellectual development. I describe his teachers and his own autograph manuscripts. The study then follows Poppers’ return journey to Kraków (via Damascus and Istanbul) to circulate Lurianic texts. He eventually went back to Jerusalem (via Lviv and Istanbul) where he died. The dissertation uses the theories and methods of the history of knowledge and manuscript studies to shed light on the global history of early modern kabbalah.

The oviduct is a pivotal and central reproductive organ that provides the finely tuned micromilieu for gametes’ maturation and early embryonic development. In vitro models of primary oviductal epithelium cells, derived from human clinical samples or food industry byproducts, not only comply with the 4Rs (replacement, reduction, refinement, and rehabilitation) framework for addressing ethical concerns on animal experimentation but also build a platform for functional experimental science. Culture conditions, such as media, have been optimised to allow for the investigation of oviduct functions. Since 5% CO2 and atmospheric O2 are the standard conditions for the vast majority of cell cultures, the actual O2 availability for the cells in the cultures and its comparability with the physiological conditions informing a specific cell environment have often been neglected variables in cell culture procedures. In the oviduct, O2 levels range from 4 to 10%, varying among mammalian species. Additionally, maternal stress and/or elevated glucocorticoid levels are associated with impaired fertility in both humans and animals. Gametes and embryos are particularly vulnerable to the environment in which they develop, especially in stressful conditions. Although previous studies have shown that reproductive performances were impaired due to the elevation of cortisol, the direct actions of physiological cortisol on oviduct epithelial cells have been elucidated less well. This study therefore aimed to explore the potential effects of O2 and cortisol on the oviduct epithelium. First, the effect of O2 tension on the oviduct epithelium was investigated using an established air-liquid interface (ALI) culture model based on primary porcine oviduct epithelial cells (POEC). The O2 levels in the incubator were set to 5% or 18% O2 during culture, representing physiological and supraphysiological conditions, respectively. Both conditions were applied with two different media regimes and cells were cultured for approximately 4 weeks in the respective conditions. Regardless of the O2 tensions or media conditions, the cultured cells developed a differentiated epithelial monolayer containing both ciliated and secretory cells. The supraphysiological level of O2 (18%) enhanced the differentiation and ciliogenesis in POEC. Notably, O2 tensions dramatically affected the production and content of the apical fluid, altered cellular composition, and influenced the expression of key oviductal function genes in POEC. Secondly, to explore the long-term effect of physiological stress-induced cortisol levels on the oviduct epithelium, an in vitro ALI model based on primary bovine oviduct epithelial cells (BOEC) was used, with basolateral administration of cortisol for 3 weeks after differentiation.   Chronic exposure to cortisol significantly disrupted the architectural integrity of the oviduct epithelium. In addition to activating glucocorticoid signalling genes, cortisol also considerably reduced gene expression associated with oviduct functionality, apoptosis, and inflammation in BOEC. Moreover, the expression of the gene HSD11B2, coding for a cortisol-metabolising enzyme which converts bioactive cortisol to inactive cortisone, was downregulated dramatically, suggesting that the oviduct was less capable of metabolising cortisol under constant treatment. To summarise, differential O2 exposure using the ALI system mimics physiological conditions, providing valuable insights into how oviduct epithelial cells adapt to their environment and maintain homeostasis. The use of both one- and/or two-step media regimes resulted in high-quality outcomes in the oviduct epithelial cells (OEC) study, underscoring the critical role of O2 levels in cell culture. Maintaining physiologically representative conditions is essential not only for the health and longevity of cell culture but also for improving reproducibility. The BOEC study results indicated that chronic exposure to cortisol impairs oviduct epithelium functions at multiple levels, including adverse effects on cellular integrity and gene regulation. This indicates that stress-induced perturbation of the oviduct potentially impairs fertility. Comparing the effect of chronic physiological cortisol on the oviduct epithelium in pigs and cattle revealed species-specific responses, particularly in the regulation of HSD11B2, indicating differing capabilities for metabolising cortisol. These findings highlight the importance of finely tuned oviduct regulation as a prerequisite for creating the microenvironment essential for gamete maturation, fertilisation and embryo development.

The oral mucosa is a crucial physical barrier in the oral cavity, protecting underlying tissues from microbial invasion, physical and chemical stimuli. This barrier function is maintained by the stratified oral epithelium and tight junction proteins. When this barrier is compromised, oral diseases such as periodontitis and oral lichen planus can occur, which are often associated with elevated levels of inflammatory markers, including IL-6, IL-8, TNFα and IL-1ß. In addition to its protective function, the oral epithelium also acts as a barrier to topical drugs, reducing their efficacy. Nanocarriers, such as core-multishell nanocarriers (CMS-NCs), offer a promising approach to improve drug delivery across the oral mucosa.

This study investigated cellular events in oral inflammation and the potential of CMS nanocarriers as a topical anti-inflammatory treatment for oral mucosa. Both 2D and 3D cell culture systems were used as research models. Characterization of the 3D model showed properties very similar to in vivo conditions, including a tissue architecture of multilayered epithelium and lamina propria with fibroblasts, tight junction formation and cell differentiation. Treatment of the models with TNFα induced inflammation, as evidenced by increased levels of IL-6 and IL-8, and led to enhanced claudin-1 expression, which in turn improved membrane integrity. In addition, wound healing was accelerated by TNFα. These results suggest a protective role of epithelial cells in the early phase of inflammation. Furthermore, activation of the ERK/MAPK signaling by TNFα contributed to IL-8 secretion, highlighting a potential target therapeutic target to reduce oral inflammation.

This study further examined the application of CMS nanocarriers as a topical anti-inflammatory treatment for the oral mucosa using dexamethasone-loaded CMS nanocarrier (Dx-CMS). Using an enzyme-linked immunosorbent assay (ELISA), Dx-CMS was shown to reduce IL-6 and IL-8 secretion more efficiently than ethanolic dexamethasone solution or dexamethasone-containing cream. However, CMS nanocarriers showed reduced adhesion in the presence of saliva, highlighting the need to improve their mucoadhesive properties. Mussel-inspired catechol functionalization is a promising approach to overcome this limitation. Using CMS nanocarriers coupled or loaded with fluorescent dyes, it was shown that CMS nanocarrier with 8% catechol content (CMS-C0.08) exhibited better mucoadhesive properties than the non-functionalized CMS nanocarrier. Furthermore, the anti-inflammatory activity of dexamethasone-loaded CMS-C0.08 (Dx-CMS-C0.08) was evaluated and compared to the dexamethasone-loaded non-functionalized CMS nanocarrier (Dx-CMS). Both Dx-CMS and Dx-CMS-C0.08 showed comparable anti-inflammatory effect when applied to the 3D oral mucosal model for 24 and 48 h. However, when applied dynamically on cell monolayers, which reflects the dynamic environment of the oral mucosa and the practical application in the treatment, Dx-CMS-C0.08 exhibited a better anti-inflammatory effect than Dx-CMS.

Overall, this study provides valuable insights into the cellular mechanisms of oral inflammation and highlights the potential of catechol-functionalized CMS nanocarrier, particularly CMS-C0.08, as an effective topical drug delivery system to improve the treatment of oral inflammatory diseases. Finally, this study highlights the importance of the human 3D model, which is able to better simulate in vivo conditions compared to conventional 2D cell culture systems and could serve as an important alternative to animal models in further investigations.

The transition from solitary individuals to societies is considered a major evolutionary transition. An insect society, or colony, is a complex system composed of many interdependent nestmates through whose interactions emerge a certain level of order and robustness. In a termite colony, order and robustness can be considered to be synonymous with division of labour and a social immune system, respectively. How these emergent properties evolved remains a major unanswered question in evolutionary biology. Here, I aim to tackle this topic from a genomic and transcriptomic perspective. First, I engaged in the sequencing of over 47 genomes of termites and cockroaches in order to generate a previously lacking basis of fundamental genomic knowledge, increasing the number of high-quality termite genomes by six-fold. Using this foundation, I first investigated how genomic traits evolved over termite phylogeny, and linked multifaceted patterns of gene and genome evolution to major shifts in termite diet and symbiosis. Secondly, I explored the genomic and genetic bases of sociality by comparing genomes and gene expression patterns across 29 near-chromosome quality cockroaches and termite genomes sampled along a broad spectrum of social complexity, including termite lineages representing convergent transitions towards bifurcated development and true worker phenotypes. Alongside global genomic signatures of selection, I examined patterns of gene family expansion and contraction at key ecological and social transitions. Comparative analysis of differentially expressed genes and co-expression networks are then conducted to search for evidence of conservation and co-option in the termite “genetic toolkit” and to gain insight into the evolutionary origins of termite division of labour. Thirdly, I investigated the evolution of termite immune genes and their relationship with social and ecological traits. I analyzed the evolution of 34 immune gene families and characterized the major components of four canonical immune pathways. I discuss how the evolution of certain immune gene families may have enabled social immunity to evolve and be maintained. Finally, I bring together these two emergent properties, sociality and social immunity, alongside their genomic basis to discuss their commonalities and potential interdependency, and by using sociality in termites as a case study, I consider the potential of a general molecular mechanism for the emergence of evolutionary innovation.