Dissertationen/Habilitationen

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The role of agri-food related initiatives in sustainability transitions of agri-food systems
(2025) Elsner, Friederike
Agri-food systems both contribute to global environmental change and are simultaneously affected by its consequences. Thereby, human activity and interactions shape desired and undesired agri-food systems’ properties. The undesired properties of current agri-food systems result in environmental, social and economic costs. Sustainability transitions of such systems are influenced by changes in social relations and deeper structural mechanisms. Individuals and groups of individuals or initiatives engage in activities, taking actions for agri-food system change. The ways these initiatives engage in change reveal systems’ malfunctions and provide insights into potential solutions and strategically relevant entry points for fostering engagement. Moreover, the ways these initiatives engage in change offer insights into tensions, goal conflicts, collaborations and resource conditions under which the initiatives operate. Existing agri-food literature on initiatives often portrays these initiatives as bottom-up driven actors within the niche. However, as agri-food system sustainability transitions are ongoing transition processes and some global or supra-national agreements to sustainable development are set in place, it is worth questioning whether all transformative activities indeed remain confined to the niche level. Drawing on transition theory, this research elaborates on the functions of agri-food related initiatives (AFIs) and the activities they perform to realise their goals as well as the influencing factors in this endeavour. Thereby, this research builds on transformative social innovation and intermediary conceptualisations and elaborates on the necessary adaptations for agri-food system analysis. The multi-level perspective on socio-technical transitions (MLP) is used to structure the analysis of the activities taking place, the functions that are being fulfilled and the influencing factors being faced. A systematic review of 58 articles on the use of MLP in agri-food system sustainability transition research paves the way for this research’ empirical investigations. The empirical analysis relies on 22 semi-structured interview transcripts conducted with 17 AFIs engaged in making their local food system more sustainable from five territorial cases in Europe (Denmark, Germany, Italy, Poland) and Northern Africa (Morocco) and on survey data of Food Policy Groups (FPGs) (n = 260), as one specific group of AFIs, across United States, middle Europe (mainly Germany) and Australia. Data is analysed using a mixed-methods approach, applying qualitative coding and statistical measures. The results show that AFIs aim to contribute to bring about change by proposing mainly agri-food related social innovations and by intermediating in the context of changing practices and social relations. Thereby, their role is influenced by drivers and barriers but not so much by their relationship to government or their type of organisation (in particular for FPGs as AFIs). A cluster is derived structuring the socially innovative activities according to social interaction processes and agri-food fields. This cluster may inspire policymakers to foster enabling environments for AFIs and support informed decision making on the types of social innovations that future agri-food systems should incorporate. The analysis of the intermediary functions shows that AFIs (here especially FPGs) intermediate between actors at the interface of civil society, science, policy and practice and assume their role through nine intermediary functions. Whether the identified niche and intermediary functions and activities are sufficient for the social innovations to diffuse remains an open question within the scope of this thesis. However, the functions and activities can be compared to those functions that the literature suggests as essential for the diffusion of technological innovation systems. Based on this comparison, the necessary functions for agri-food related social innovation systems are derived which partly deviate from the functions of technological innovation systems. Future research could take this up and develop a conceptualisation on the functions necessary for the diffusion of social innovation systems, currently lacking in the literature. The AFIs operate in interaction with other system elements, which are perceived as either enabling or constraining to their activities. The drivers AFIs face seem to be more about social relations and people whereas the barriers tend to be more of a structural or processual nature, implying that a general societal acceptance of AFIs’ activities and functions seems to be present, facilitating and justifying structural changes. The analysis of challenges suggests that support mechanisms, especially funding schemes, should be tailored to the development of social innovations and funding should not only be granted to innovation development but also to their (long-term) implementation. The results indicate that role constellations within AFIs seem to matter when it comes to the actions an AFI focuses on, which could be further pursued in future research.
Sustainable livestock systems in Ethiopia: Assessment of the status quo and options for improvement with a focus on animal welfare, market systems, gender roles and human-wildlife conflict management
(2026-01) Sahile, Dagmawit Giref
This study brings together three strands of research to provide a holistic understanding of animal welfare challenges and opportunities in Ethiopia, focusing on farmers' willingness to engage in welfare initiatives, market-level welfare conditions, and traditional methods for managing human-wildlife conflict. Together, these findings offer critical insights for policy and program development aimed at improving both animal well-being and rural livelihoods. The first chapter explores farmers’ preferences and willingness to participate in voluntary animal welfare schemes using mixed logit models in preference and willingness to pay space to assess the relative importance of different attributes of animal welfare schemes on farm households’ participation. Results show that financial incentives are the most significant factor influencing participation. Farmers indicated a need for compensation equivalent to 11% of their annual livestock sales to participate in welfare programs. More demanding welfare improvements such as optimal welfare standards or improved training required significantly higher compensation, up to 25–26% of livestock sales per year. These findings underline the importance of aligning welfare improvements with tangible economic benefits to ensure farmer engagement. Policy recommendations include the development of flexible, farmer-oriented schemes that combine financial incentives with accessible training and community-based approaches. The second chapter assesses the state of animal welfare in three livestock markets: Addis Ababa (terminal), Adama (secondary), and Meki (local). The analysis reveals substantial variation in infrastructure and animal handling practices. While the terminal market offers relatively humane conditions and access to basic amenities such as water and shelter, the local and secondary markets lack such facilities and are characterized by poor handling practices, including forceful movement and lack of rest. These conditions contribute to animal stress and injury, undermining both welfare and market efficiency. Additionally, the study highlights gender inequalities in market participation, with women facing systemic barriers. To address these challenges, the study recommends investment in welfare-supportive infrastructure, implementation of enforceable national welfare standards, comprehensive training for handlers, and policies that actively promote gender inclusion. The third chapter focuses on human-wildlife conflict around Nech Sar National Park, analyzing the economic and social impact of livestock predation and crop damage. Households within 16 kilometers of the park suffer average annual losses of $76.78, which is approximately 77% of their annual income, due to wildlife incursions. While traditional guarding practices are widely used, most respondents viewed them as ineffective unless rigorously applied. Gender differences were also evident: male-headed households experienced greater cattle losses, while female-headed households were more affected by poultry predation which reflects differences between genders in species kept. The findings emphasize the need for a combination of modern and traditional strategies, including expanded buffer zones, improved fencing, gender-sensitive planning, and community engagement to reduce conflict and protect livelihoods. Taken together, these three studies provide a comprehensive picture of the multifaceted issues affecting animal welfare and rural livelihoods in Ethiopia. They underscore the importance of integrating financial incentives, infrastructure investment, gender equity, and local knowledge into national policy. By addressing the economic factors of farmers, improving market conditions, and supporting community-based conservation, Ethiopia can move toward more sustainable and inclusive animal welfare systems.
Schusstodesfälle aus dem Einzugsgebiet des Instituts für Rechtsmedizin Gießen: eine retrospektive Analyse der Jahre 2009 bis 2018
(2024) Wolf, Paula Marie
Die Untersuchung und Beurteilung von Schusstodesfällen stellt einen kleinen, aber be-deutsamen Anteil an der rechtsmedizinischen Arbeit dar, wobei eine interdisziplinäre Zusammenarbeit zur umfänglichen Aufarbeitung der Hintergründe erforderlich wird. Vergangene Studien zeigten regionale Unterschiede in Häufigkeiten und Arten von Schusstodesfällen. Unsere retrospektive Auswertung der im Zeitraum von 2009 bis 2018 am Institut für Rechtsmedizin Gießen durchgeführten 5400 Sektionen und Leichenschauen ergab 111 Todesfälle in Zusammenhang mit einem Schusswaffengebrauch. Es erfolgte eine weitere Analyse der allgemeinen Daten, demografischen Merkmale der Verstorbenen, Schussverletzungen, Todesumständen und -orten, verwendeten Waffen, weiterführenden Untersuchungen und etwaigen Tätern und Tathintergründen. Die 111 Schusstodesfälle entfielen auf etwa 24 % Homizide, 75 % Suizide sowie knapp 1 % Unfallgeschehen. Etwa 87 % der Schusstoten waren männlichen, etwa drei Viertel der Verstorbenen waren älter als 50 Jahre. Der häufigste Fundort war sowohl bei Homiziden als auch bei Suiziden das häusliche Umfeld. Das Vorliegen nur einer singulären Schussverletzung war führend, mehr als drei Schussverletzungen fanden sich nur in der Gruppe der Homizide. Die maximale Schussanzahl lag hier bei 17 Schussverletzungen. Langwaffen waren bei Viertel der Fälle zu finden, innerhalb der Homizide nur in 18 %. Die Kurzwaffen überwogen hier deutlich mit 71 %. Eine Beurteilung des Legalitätsstatus der Waffe war in etwa zwei Drittel aller Fälle möglich. Weiterführende Untersuchungen, wie eine postmortale Bildgebung oder forensisch- toxikologische Untersuchungen fanden in ausgewählten Fällen statt. Ein Vergleich mit Datenerhebungen aus rechtsmedizinischen Instituten in Deutschland und anderen Ländern zeigte überwiegend Gemeinsamkeiten hinsichtlich Geschlechts- und Altersverteilung der Verstorbenen. Unterschiede zeigten sich beispielsweise bei der Art der verwendeten Waffe oder auch bei den Einschusslokalisationen. Besondere Fälle in unserem Kollektiv, wie etwa Tötungen mit nachfolgender Selbsttötung oder kombinierte Suizide, zeigten die Notwendigkeit einer sorgfältigen, interdisziplinären Zusammenarbeit zur Beurteilungen und Einordnung der Taten und Hürden dieser auf. Es fiel zudem eine bemerkenswerte Diskrepanz zwischen der Anzahl hessenweit rechtsmedizinisch untersuchter Schusstodesfälle und der in der Todesursachenstatistik für den gleichen Zeitraum aufgeführten Fälle auf, die Fragen zum Procedere beim Umgang mit Schusstodesfällen aufwirft.
Accessing Arene-Fused Eight-Membered Carbo- and Heterocycles via Bidentate Lewis Acid Catalysis
(2025) Große, Michel
Eight-membered carbo- and heterocycles constitute unique structural elements not only found in a plethora of biologically active natural products and medicinally relevant synthetic compounds, but also in various functional molecules and materials. Especially arene-annulated cyclooctanoids have attracted increasing attention as they combine the properties of rigid aromatic structures and flexible cyclooctene-derived ring systems. However, entropic and enthalpic difficulties generally encountered in the synthesis of medium-sized rings have largely hampered the development of general synthetic methods to access these structures. In this thesis, new strategies for the synthesis of arene-annulated eight-membered carbo- and N-heterocycles were developed by employing a boron-based bidentate Lewis acid (BDLA) catalyst previously established in our group for facilitating inverse electron-demand Diels−Alder (IEDDA) reactions of phthalazines. The utilization of different cyclooctyne derivatives as highly reactive dienophiles gave rise to a series of cyclooctenes and cycloocta-1,5-dienes fused to substituted polycyclic aromatic hydrocarbons. X-ray crystallographic analysis and variable temperature NMR studies of selected derivatives provided valuable insights into the conformational behaviour of these polycyclic structures. Additionally, the same catalytic principle was employed to develop a one-step synthesis of arene-annulated eight-membered nitrogen heterocycles from phthalazines and Boc-protected 2-azetine as a strained alkene dienophile. Key to this transformation was the formation of a highly reactive o-quinodimethane intermediate that thermally rearranged in a 10π electrocyclic ring opening to yield the desired azocine structures. These mechanistic considerations were supported by the isolation and characterization of the main by-product, and final proof for the eight-membered ring structure was obtained via X-ray crystallographic analysis of a degradation product.
Eine retrospektive monozentrische Analyse der postoperativen Ergebnisse bei Patienten mit akuten und chronischen Pathologien des Aortenbogens im Hinblick auf die Mortalität im Krankenhaus und schwerwiegende postoperative Ereignisse
(2025) Tsobanoudi, Victoria
Ziel: Untersuchung der postoperativen Krankenhausmortalität und schwerwiegenden postoperativen Komplikationen (Sepsis, Multiorganversagen, postoperatives akutes Nierenversagen, neurologische Komplikationen und Herzrhythmusstörungen) durch eine retrospektive Datenanalyse von Patienten mit einer Aortendissektion oder einem Aortenaneurysma, die mittels Frozen-Elephant-Trunks (FET) behandelt wurden. Des Weiteren wurde die technische Entwicklung sowie Steigerung der chirurgischen Fertigkeiten der selektierten Operateure im Verlauf von 15 Jahren untersucht. Methode: Eine monozentrische retrospektive Datenanalyse des Patientenkollektivs bei einem akuten Aortensyndrom mit der operativen Versorgung mittels FET zwischen den Jahren 2008 und 2022 in der Kerckhoff Klinik in Bad Nauheim zur Untersuchung der o. g. primären, sekundären und tertiären Ziele. Das Patientenkollektiv besteht aus 145 Patienten, geteilt in zwei Gruppen (Ära 1: 2008 – 2017 mit 75 Patienten vs. Ära 2: 2018 – 2022 mit 70 Patienten). Ergebnisse: Die Untersuchung der primären Fragestellung dieser Arbeit zeigte eine Gesamtkrankenhausmortalität von 15% zwischen den Jahren 2008 bis 2022 und bestätige die Ergebnisse der bisherigen Studien in diesem Zusammenhang, die durchschnittlich eine Mortalität von ca. 17% aufwiesen. Im Rahmen der Analyse der sekundären Fragestellungen dieser Arbeit wurde als erstes das Auftreten einer Sepsis mit 5% und einer Mortalität von 71% aus dieser Gruppe der Patienten mit Sepsis verzeichnet. Des Weiteren lag die Entwicklung eines Multiorganversagens bei den Patienten mit einer Sepsis ebenfalls bei 71% und die Notwendigkeit einer Nierenersatztherapie bei 86%. Das Auftreten eines akuten Nierenversagens lag bei 25%. Die Untersuchung der neurologischen Komplikationen ergab eine Apoplex-Rate von 21%. Durch die operative Therapie konnte eine präoperative Organ-Malperfusionsrate von 24% des Gesamtkollektivs (n = 145) auf eine postoperative Malperfusionsrate von 6% reduziert werden. Bei 37% der Patienten des Gesamtkollektivs konnte ein postoperatives Vorhofflimmern diagnostiziert werden. Bei der Beantwortung der primären und sekundären Fragestellungen dieser Arbeit konnte festgestellt werden, dass die Etablierung der FET-Operationsmethode durch die selektierten Operateure keinen Einfluss auf die Operationsergebnisse im Verlauf der Zeit hatte. Fazit: Die Ergebnisse der retrospektiven Datenanalyse der Patienten der Kerckhoff Klinik korrelieren weitestgehend mit den Daten der bisherigen Studien, die sich ebenfalls mit den Krankheitsbildern des akuten Aortensyndroms und dem Aortenbogenersatz befasst haben.
Beleuchtung der Blackbox raumbezogener Entscheidungsfindung und darauf aufbauende methodische Weiterentwicklung: Alternativenbewertung und Alternativenabwägung beispielhaft am kommunalen Planungsprozess
(2025) Müller, Christin Juliana
Die kommunale Entscheidungsfindung mit der Bewertung und Abwägung von Alternativen ist kein geradliniger Prozess, sondern ein Balanceakt zwischen Vision, Verhandlung und Realität. Dabei ist die Entscheidungsfindung im informellen kommunalen Vorentwurf von Planungsprozessen innerhalb der Raumplanung ein multidimensionaler und dynamischer Prozess, der durch verschiedene Rahmenbedingungen sowie divergierende Interessen und eine hohe Komplexität geprägt ist. Die Kunst dieser Entscheidungsfindung zeigt sich nicht nur in der Wahl der Methode, sondern auch im Umgang mit ihren Grenzen. Die inhärenten Determinanten wie abweichende Zielvorstellungen, politische Interessen, unterschiedliche Vorgehensweisen und abweichende Planungsverständnisse begründen zentrale Herausforderungen und verlegen den Prozess in eine Blackbox. Die vorliegende Forschung untersucht anhand einer Mixed-Methods-Analyse, bestehend aus Fallstudien, Experimenten mit Studierenden, einer Fokusgruppe und einer bundesweiten Umfrage, wie raumbezogene Entscheidungsprozesse mit dem besonderen Fokus auf der Bewertung und der Abwägung von Alternativen in der kommunalen Raumplanung ablaufen und methodisch weiterentwickelt werden können. Dabei lautet die zentrale Forschungsfrage: „Wie erfolgt die Entscheidungsfindung in kommunalen Planungsverfahren, und welche Ansätze ermöglichen eine methodische Weiterentwicklung dieses Teilprozesses?“. Die theoretische Grundlage findet sich in der Entscheidungstheorie und der Darstellung von Planungsprozessen im Kontext der Raumplanung mit planungstheoretischen Ausführungen. Die Ergebnisse der im Rahmen dieser Arbeit beleuchteten Blackbox verdeutlichen, dass Entscheidungsprozesse im räumlichen Kontext essenziell durch die bestehenden inneren, äußeren und prozessualen Rahmenbedingungen beeinflusst werden und oft einen iterativen Charakter aufweisen sowie kommunikative Aushandlungsprozesse umfassen. Allen Prozessen ist eine mangelnde einheitliche Verständigung auf Begrifflichkeiten und Abläufe sowie ein Mangel an Transparenz inhärent. In der Analyse konnten drei Typen der Entscheidungsfindung identifiziert werden: die freie, die strukturierte und die diplomatische Entscheidungsfindung. Innerhalb dieser zeigen sich verschiedene Ausprägungen und teils auch Überschneidungen. Diese Typologie ermöglicht eine präzisere Systematisierung kommunaler Entscheidungsprozesse und bietet eine fundierte Basis für methodische Optimierungen. Die drei Typen werden in einem neu entwickelten raumbezogenen Entscheidungsfindungsmodell verortet und anhand dessen weiterentwickelt. Unabhängig ihres Potenzials für eine fundierte Entscheidungsfindung finden Planungsmethoden in der Praxis nur begrenzte Anwendung. Entscheidungsfindung wird nicht nur von einzelnen methodischen Ansätzen determiniert, sondern ist abhängig von der adäquaten Einbettung in die jeweiligen Rahmenbedingungen. Die vorliegende Arbeit schlägt dabei Weiterentwicklungsansätze mit strukturierendem Charakter hervor. Um den Anforderungen unterschiedlicher Planungskontexte gerecht zu werden und fundierte konsensfähige Entscheidungen zu ermöglichen, werden Handlungsempfehlungen für die Praxis aufgezeigt. Sie zeigen, dass eine methodische Schärfung und strukturelle Anpassung erforderlich sind, um Planungsentscheidungen zielgerichteter und transparenter zu gestalten. Außerdem beinhalten sie einen neu entwickelten raumbezogenen Entscheidungsfindungsfaktor zur Klassifizierung der Planungsprozesse; den Einsatz von Prozessoptimierungen und Projektmanagement, Datenverarbeitung sowie KI; die Betrachtung von Alternativen durch Wettbewerbsverfahren im kleinen Maßstab sowie eine Aushandlungsarena mit Verfahrensweisen zur Aushandlung.
Untersuchung der suppressiven Wirkung des Fibroblast Growth Factor Receptor Inhibitors Fexagratinib (AZD4547) auf den Verlauf einer experimentellen autoimmunen Enzephalomyelitis im Mausmodell
(2025) Gurski, Fynn
Einleitung: Multiple Sklerose (MS) ist eine autoimmune entzündlich-demyelinisierende Krankheit, die weltweite Inzidenz liegt bei rund 3 Millionen Menschen im mittleren Alter und weist eine meist progressiv verlaufende Symptomatik auf, die neben schweren motorischen Einschränkungen auch psychische Komplikationen beinhaltet. Im Rahmen vorausgegangener Untersuchungen zeigte sich eine mögliche Beteiligung der FGFR, VEGFR2 und CSF1R Signalwege an der Pathogenese der autoimmunen experimentellen Enzephalopathie (EAE), einem Modell für MS. Vorarbeiten mit dem selektiven FGFR-Inhibitor Infigratinib erzielten bereits gute Resultate und stellten die Frage nach einer wirkungsvolleren Substanz und einem Therapieregieme samt einer möglichen Dosierung für den Einsatz im Menschen. Versuchsansatz: Fexagratinib (AZD4547) ist ein Multikinase-Inhibitor für den FGFR1 und 2, VEGFR2 und CSF1R. In diesem Versuch wurde ab dem Zeitpunkt des Auftretens erster Symptome Fexagratinib in einer Dosierung von 6,25 bzw. 12,5 mg/kg über zehn Tage oral an EAE-induzierte Mäuse verabreicht. Die Wirksamkeit wurde jeweils in einer akuten Phase am Höhepunkt der Symptome (20 Tage p.i.) und in einer chronischen Phase der EAE (42 Tage p.i.) untersucht. Ziel war es, die Symptomlast und den Krankheitsprogress abzumildern und darüber hinaus neuroregenerative Prozesse wie die Remyelinisierung zu unterstützen. Ergebnisse: In der akuten Phase zeigte sich eine Reduktion schwerer Symptome von 89% bzw. 100% in der 6,25 und 12,5 mg Gruppe. In der chronischen Phase konnte niedrig dosiertes AZD4547 die Symptomatik um 68% reduzieren, in der Hochdosis-Gruppe wurden schwere Symptome erneut komplett verhindert. Immunhistochemisch zeigte sich eine signifikant reduzierte Entzündungsaktivität von T- und B-Lymphozyten sowie von Macrophagen/Microglia in Läsionen der weißen Substanz des Rückenmarks in beiden Phasen des Experiments. Gleichzeitig steigerte AZD4547 die Anzahl Myelin-produzierender Oligodendrozyten und ihrer Vorläuferzellen und erhöhte die Dichte myelinisierter Axone im Rückenmark. Fazit: Der Einsatz des Multikinase-Inhibitors Fexagratinib stellt eine potentiell gut wirksame neue Therapieoption zur Abmilderung krankheitsbezogener Symptome und der Verlangsamung des Krankheitsprogresses bei MS dar. Darüber hinaus unterstützt er die Remyelinisierung von Axonen und wirkt neuroregenerativ. Der Einsatz von Fexagratinib in einer klinischen Studie mit einer Äquivalenzdosis von 1 mg/kg im Menschen würde weitere wichtige Erkenntnisse zur Verträglichkeit und Wirksamkeit einer möglichen künftigen Anwendung bei MS-Patienten liefern.
The Impact of London Dispersion Interactions in Solution: Bring [a Molecular] Balance to the [LD] Force!
(2025) Schümann, Jan Michael
The contribution of London Dispersion (LD) to the intramolecular folding behavior of a cyclooctatetraene (COT)-based molecular balances in a variety of solvents was investigated. As part of this investigation, a well-defined system, represented by a tert-butyl dimer with an intramolecular distance of 2.44 Å was synthesized. The folding behavior of this molecular balance was then investigated in various solvents with increasing solvent polarizability (SP) to examine the contribution of London interactions. We showed that the free enthalpy of the isomerization reaction in each solvent follows approximately the same value. Gibbs free energy can be readily measured by determination of the ratio of 1,4- to 1,6-isomers. It was found that the entropy in each solvent system is responsible for the diminishing effect on ΔG values. The answer to the question of Yang et al. “How much does LD contribute to molecular recognition in solution?” is that “It depends!” The lowest ratio of 1,4- and 1,6-isomers was found in purely aliphatic solvents, this may indicate a compensating effect of dispersion interactions between the solvent and the balance. DMSO and chloroform clearly showed a preference for the 1,6-isomer. However, it became clear through additional energy decomposition analyzes (EDAs) that LD is the predominant force responsible for folding. The extension of the concept was investigated by the synthesis of adamantyl and diamantyl COT derivatives. The molecular balances still have an attractive distance of 2.4 Å for dispersion, but the polarizabilities and the expansion regarding the solvent accessible surface (SAS) of the substituents become significantly larger, which allows more interaction with the surrounding solvent. Longer aliphatic chain hydrocarbons (n-hexane, n-octane and n-dodecane) were therefore chosen as solvents to suit the growth of the derivatives. In collaboration with the Max-Planck Institute for Coal Research, computations at the highest level were carried out using implicit and explicit solvent models to determine the influence of the solvents on the folding behavior. The computational and experimental results lead to the conclusion that an adhesion occurs through the solvent and that the “rigid rotors” of the diamondoid derivatives make an exclusive contribution to the entropy. In every study, the folded derivative is always preferred.
Essays on Accounting – Compliance, Education and (Non-)Financial Reporting
(2025) Pleger, Alana Sarina
This dissertation addresses current issues in financial accounting and comprises four research papers structured into three sections: Compliance (Section A), Accounting Education (Section B), and Financial and Non-Financial Reporting (Section C).
The empirical study in Section A examines the effect of two control design elements on employees’ performance misreporting behavior. The experimental findings suggest that ethical considerations can be reintegrated into employees’ decision-making depending on the design of control elements, specifically the presence of detrimental effects on others and the level of control result transparency.
The research paper in Section B evaluates the animated video series “Bibi Bilanzierung” as an edutainment-based teaching tool. Using survey data and a field experiment, the study finds that the video-based teaching concept increases students’ motivation and exam performance in an introductory accounting course.
Section C comprises two normative research papers on financial and non-financial reporting. Research Paper C1 analyzes corporate pay transparency reports following the introduction of the German Transparency in Wage Structures Act and derives best-practice recommendations. Research paper C2 examines the substance-over-form principle in parent-subsidiary relationships within German group accounting. Overall, the dissertation provides empirical and conceptual insights into the effective design and implementation of accounting instruments across education, control systems, and corporate reporting.
Restoring semi-natural grasslands in Central Europe with plant material transfer – achievements, success factors, and knowledge transfer
(2025) Sommer, Leonhard
Since the industrial revolution, land use changes and intensification of use have drastically reduced the area of species-rich, semi-natural grasslands in Central Europe. Active restoration of these ecosystems is therefore necessary and increasingly demanded by legislation. One method to (re-)introduce target plant species is the transfer of seed-containing plant material cut from species-rich, semi-natural donor sites. Given the urgency of the restoration task, the aim of this thesis is to contribute to understanding the success factors of this method, particularly in practice. In a first study, 20 recipient sites of floodplain meadow restoration in Hesse, Germany, were revisited and investigated for vegetation composition in comparison to their corresponding donor sites 13-16 years after plant material transfer. To assess the potential for livestock feeding, biomass yield and energy contents were measured, too. In a second study, 41 recipient-donor site pairs from practical grassland restoration projects in different regions of Germany and Luxembourg spanning a broad moisture gradient were investigated. Vegetation was recorded, and soil analyses and information on restoration from the practice partners were used for success factor identification. In a third study, 33 practitioners of grassland restoration with plant material transfer were interviewed to compare their views on the topic to European scientific literature. All three studies underline the critical importance of abiotic site conditions supporting the target plant communities. A frequent long-term problem is too high productivity of recipient sites, particularly in floodplain meadows. Site conditions, along with competition for the introduced plant species, are strongly dependent on the previous state of recipient sites. Raw soils, e.g., obtained by topsoil removal, provide low-competitive, nutrient-poor conditions, often enhancing restoration success. Generally, competition for the introduced species is lowered by adequate soil preparation, whose effect may, however, diminish over time. Harvest time for the plant material is decisive for the pool of transferable target species, and supplementing this pool by additional introduction methods, such as sowing, is useful. For maintenance of restored grassland communities, appropriate low-intensive post-restoration management is necessary. Sufficient biomass yield and energy content enable integration in feeding rations for livestock, buffering the costs of management. Practitioner interviews revealed that overarching factors such as project organisation, trust-building, and experience strongly influence how well the previously mentioned conditions can be met. To support grassland restoration in the coming decades, a challenge increased by climate change, intense knowledge exchange between science and practice and among practitioners is advised.
Einfluss einer pulmonalen Ballonangioplastie bei Patienten mit chronisch thromboembolischer pulmonaler Hypertonie auf elektrokardiographische Parameter
(2025) Ley, Lukas Maximilian
Einleitung: Die chronisch thromboembolische pulmonale Hypertonie (CTEPH) ist der wichtigste Vertreter der Gruppe 4 der pulmonalen Hypertonie und tritt bei etwa 2-3% der Überlebenden einer Lungenembolie als Langzeitfolge auf. Eine der verfügbaren Therapiemöglichkeiten ist die pulmonale Ballonangioplastie (BPA). Die CTEPH kann mit typischen elektrokardiographischen Zeichen einhergehen, welche sich nach BPA bessern können. Material und Methoden: Die vorliegende Studie schloss von März 2014 bis Oktober 2020 retrospektiv 150 Patienten (53% Frauen, 47% Männer, medianes Alter: 64 Jahre) ein. Alle Patienten erhielten ein 12-Kanal-EKG und eine Rechtsherzkatheteruntersuchung vor, sowie sechs Monate nach BPA. Hauptziel der Studie war es, die Prävalenz elektrokardiographischer Pathologien bei der CTEPH und deren Veränderung nach BPA darzustellen. Ergebnisse: Die vorliegende Studie konnte bestätigen, dass typische elektrokardiographische Pathologien der CTEPH beobachtet werden, diese sich nach hämodynamisch erfolgreicher BPA zurückbilden und mit hämodynamischen Parametern korrelieren können. Besonders auffällig war der Hauptparameter "R V1, V2 + S I, aVL - S V1". Er korrelierte mit dem mittleren pulmonalarteriellen Druck (mPAP) und pulmonalvaskulären Widerstand (PVR, r-Werte: 0,372-0,519, p < 0,001). Zudem verbesserte sich dieser statistisch signifikant nach BPA (47% vs. 29%, p < 0,001). Bei Analyse der Subgruppen war zu beobachten, dass bei einer hämodynamisch schwereren CTEPH häufiger und deutlichere elektrokardiographische Pathologien zu detektieren waren und ein EKG bei Patienten mit milder CTEPH auch vollkommen unauffällig sein konnte. Schlussfolgerungen: Die Ergebnisse der vorliegenden Studie stimmen mit der aktuellen Studienlage überein. Trotz zahlreicher Vorteile kann das EKG aktuell nur Hinweise auf eine CTEPH liefern, da es diesem, vor allem in Anfangsstadien, an Sensitivität mangelt und es allein weder die CTEPH sicher diagnostizieren noch ausschließen kann. Weitere potenzielle Einsatzgebiete wie die Vorhersage der kardiopulmonalen Hämodynamik, die Kontrolle der Therapieeffektivität, die Unterstützung beim Treffen von Therapieentscheidungen, die Risikostratifizierung oder die CTEPH-Früherkennung sowie der Hauptparameter „R V1, V2 + S I, aVL - S V1” sollten in weiteren Studien genauer erforscht werden.
Deciphering Self-Assembly Mechanisms and Chemical Reactions of Organic Building Blocks on Metal Surfaces by Chemical Bond Imaging
(2025-09-24) Wiche, Miguel
In recent years, the novel field of on-surface synthesis has been established as one of the main tools for constructing customized, low-dimensional organic nanostructures via bottom-up approaches on atomically flat metal substrates. The self-assembly of the molecular precursors, a process that often serves as pre-step of the on-surface reaction, determines the precise local arrangement of atoms and bonds in neighboring molecules, thus playing a decisive role in product formation. Thereby, intermolecular interactions between hydrogen and fluorine atoms have proven to be a valuable tool to steer molecular alignments. In this work, the mainly unexplored intermolecular hydrogen-fluorine interaction is systematically investigated on inert Au(111) and reactive Cu(111) substrates, using a linear, unilaterally fluorinated 1,2,10,11,12,14-hexafluoropentacene molecule as a model system. In the combined scanning tunneling microscopy and chemical bond imaging study, the local arrangement of hydrogen and fluorine atoms in neighboring molecules is determined in the picometer range and angular variations of a few degrees. While on Au(111) the intermolecular interactions between the molecules are the main contributor to the self-assembly, the higher reactivity of Cu(111) results in different adsorption geometries and molecular arrangements. The highly precise self-assembly study provides new insights into the on-surface interaction of hydrogen and fluorine atoms, thereby highlighting its significance for the field of on-surface synthesis. An on-surface reaction that solely takes place using halogenated precursors is the on-surface Ullmann coupling reaction, which enables the formation of covalent carbon-carbon bonds with the underlying metal surface as a catalyst. However, when applying Ullmann coupling reaction steps, complex self-assembly mechanisms can occur when halogenated precursors interact with the metal surface. Further, cleaved halogens adsorbed on the surface may potentially inhibit the reaction steps. Hence, there is a growing demand for halogen-free precursors for on-surface reactions. Recently, it has been demonstrated that halogen-free (6)Cycloparaphenylene ((6)CPP) molecules are suited to thermally induce a ring-opening polymerization reaction for the synthesis of graphene and biphenylene nanoribbons of confined widths. However, the mechanism of the ring-opening polymerization and the use of cycloparaphenylenes as precursors have not been investigated sufficiently. To contribute to the fundamental understanding of this remarkable reaction, in this thesis we systematically investigate the influence of the ring strain, which decreases with increasing ring size, using a set of cycloparaphenylenes of different sizes ((6)CPP vs. (8)CPP vs. (10)CPP). Our results demonstrate that the ring-opening polymerization is facilitated when using smaller, highly strained cycloparaphenylenes. For larger molecules with lower strain energies, the initial ring-opening is hampered, leading to only partial polymerization for (8)CPP and no polymerization in case of (10)CPP. Additionally, dehydrogenation of individual phenyl rings in intact molecules is observed for (8)CPP and (10)CPP, which further impedes the polymerization reaction.
The Effects of DNA Repair Pathway Engineering on CRISPR-Mediated Genome Editing in Neuronal Cells
(2025) Alabudeeb, Fatimah
Inherited retinal dystrophies are a group of genetically and clinically heterogeneous disorders that vary in their clinical presentation and progression, possibly leading to blindness. So far, about 332 genes, most expressed in photoreceptors, have been identified to be associated with these diseases. The relatively new genome editing field, particularly CRISPR-Cas9 mediated genome editing technology, which introduces DNA double-strand breaks (DSBs) that are subsequently repaired by the cells' repair systems, has recently drawn much attention. The major repair pathways are non-homologous end-joining (NHEJ) and homology-directed repair (HDR). One of the main obstacles to its application in the retina is the limited knowledge of DNA repair in photoreceptors. This work aims to analyze the DNA repair mechanisms, improve CRISPR Cas9 genome editing efficacy by modulating and engineering the DNA repair pathways in mature neurons using the human inducible Neurogenin iPS (iNGN) cell line, and validate it as an in vitro model system. These cells are human-induced pluripotent stem cells that differentiate into mature neurons within 4 days. In addition, the iNGN TET3KO cell line was also investigated to determine the impact of the TET3 protein at various differentiation stages. To achieve this, the iNGN cell lines and a control cell line, HEK293T cells, were transfected with BRET reporter assay plasmid using Cas9 and the inducible Cas systems (iCas). Promoter optimizations were done by replacing the CMV promoter, which can be silenced and suppressed in certain cell types, with a sustained EF1α promoter. Applying the Cas9 system, iNGN WT and iNGN TET3KO cells were tested throughout the differentiation process. Moreover, the modifications of PARP1 protein levels using PARP1 overexpression or knockout plasmids were necessary to study its influence on the DNA repair pathways of different cell lines. The BRET reporter assay was the primary quantitative technique used. The results showed decreased frameshift rates for the undifferentiated iNGN using the iCas system compared to the Cas9 system, and along with failure to use its timing control advantage, the Cas9 system was mainly used for the remaining experiments. The undifferentiated iNGN TET3KO cells' frameshift rates, as well as at the beginning of differentiation, were significantly higher than iNGN WT ones. Furthermore, the frameshift rate results of the TET3KO overexpressed cells resembled those of iNGN WT cells. After PARP1 modulation, the frameshift rates of PARP1 downregulation were greater throughout the differentiation process of the iNGNs, regardless of the HDR template addition. Interestingly, the results of the iNGN TET3KO cells were higher than those of the WT cells. For future assessment, the generation and application of iNGNs TLR3 cell lines is essential to verify the results obtained using the BRET reporter assay at the genomic level.
Charakterisierung des Down-Syndrom-Zelladhäsionsmoleküls Dscam in der angeborenen Immunantwort von Manduca sexta (L.)
(2025) Speckmann, Martin
Die Spezifität angeborener Immunmechanismen wird entscheidend von genetischer Diversifizierung und selektiver Anpassung in der Evolution von Wirt-Mikroben-Interaktionen beeinflusst. Angeborene Immunantworten von Insekten werden demnach allgemein als effizient, jedoch bedingt durch Keimbahn-kodierte Mustererkennungsrezeptoren (PRR) als eingeschränkt spezifisch beschrieben. In Zusammenhang mit exklusiver molekularer Diversität des Down-Syndrom-Zelladhäsionsmoleküls (Dscam) bei Vertretern der Pancrustacea verdichten sich Belege, die für eine Funktion als hypervariabler, Pathogen-spezifischer PRR der Immunglobulin-Superfamilie sprechen. Obwohl experimentelle Daten erregerspezifische Dscam-Spleißformen in Hämozyten von Insekten und Krebstieren sowie deren Beteiligung an In-vitro-Phagozytose von Mikroorganismen zeigen, sind Genexpressionsmuster in Hämozyten und deren Relevanz im Rahmen angeborener Immunantworten in vivo noch größtenteils unbekannt. Anhand eines In-vivo-Modells bakterieller Stimulation und monoklonaler Antikörper für spezifische Hämozytentypen wurden die Genaktivität und das Proteinmuster von Manduca sexta Dscam (MsDscam) in zirkulierenden, larvalen Hämozyten charakterisiert. Trotz geringer quantitativer Veränderungen der relativen mRNA-Level konnte eine qualitative Veränderung des differenziellen Transkriptionsmusters von MsDscam in Zusammenhang mit Hämocoel-Injektion von fixierten E. coli K12 festgestellt werden. In Abwesenheit von Immunstimulation ist MsDscam-Transkript ausschließlich in einer seltenen Population sphärischer Hämozyten mit exzentrischen Zellkernen lokalisiert. Prophenoloxidase (proPO) enthaltende Oenozytoide mit gleichen morphologischen Eigenschaften fallen unabhängig als einzige Population in Zirkulation mit membranassoziiertem MsDscam-Muster auf. Nach E. coli-Injektion ist der prozentuale Anteil von Hämozyten mit aktiver MsDscam-Transkription hingegen signifikant um das Zehnfache erhöht (p < 0,001), darunter auch Subpopulationen von Plasmatozyten und granulären Zellen. Damit vermittelt diese Dissertation zum ersten Mal in zwei Jahrzehnten immunologischer Dscam-Forschung ein fundiertes Bild immunstatusabhängiger Genaktivität in drei distinkten Hämozytentypen. Zusätzlich ergeben sich kumulative Hinweise, die eher für funktionelle Relevanz von MsDscam im Rahmen einer zweiten Immunantwort sprechen als in der Akutphase-Immunantwort nach erstmaliger mikrobieller Stimulation. Dementsprechend liefert diese Arbeit erstmals eine Grundlage für die Analyse Dscam-basierter molekularer Diversität in proPO-produzierenden Hämozyten, was zu einem erweiterten Verständnis von Oenozytoide als immunologische Masterregulatoren in Manduca beitragen kann. Typspezifische Transkriptomanalyse von Manduca-Hämozyten in Homöostase und Immunstimulation kann somit nicht nur zur Validierung der Hypothese von funktioneller Relevanz von Dscam beim Immunpriming in Insekten, sondern auch zur Aufklärung der immer noch unbekannten Regulation zellulärer Dscam-Spleißsignaturen beitragen.
Microbes in bee-plant networks: Composition characterization and their ecological implications
(2025) Shi, Haoran
Honey bees are vital pollinators in ecosystems around the world, and microbes play key roles in connecting bees and plants. Collectively, microbes, bees and plants form intricate tripartite interactions networks. Through a co-evolution, many bee- and plant-associated microbes have developed functions that benefit their hosts, including promoting growth, enhancing pathogen resistance, and aiding digestion. Microbiome associated with different hosts tend to be specific, and within bee-microbe-plant networks, both beneficial and pathogenic microbes are dynamically transmitted among hosts. In the current study, honey bee corbicular samples were collected over a two-year period from beehives at Justus-Liebig-University Giessen. Corbicular pollen is able to reflect both microbes and plants encountered by honey bees during foraging activity. Plant and microbial communities in honey bee corbicular pollen were profiled using 16S rRNA gene and plant ITS2 metabarcoding. The results indicated that the corbicular pollen microbiome exhibited clear seasonal variations, and was affected by multiple environmental factors as well as choices of forage plants. Co-occurrence network analysis further revealed specific plant-microbe associations and identified several hub plant taxa that may serve as hotspots for microbial transmissions. Following this study, we characterized bacterial and fungal microbiome of flowers from a highly insect-visited hub plant, bramble (genus Rubus), using 16S rRNA gene and fungal ITS2 metabarcoding. The data showed that insect visitation increased microbial loads on flowers and enriched specific microbial groups including fermentative and pathogenic microbes, highlighting the role of bramble flowers as hotspots for microbial transmission. In addition, insect visitation altered floral microbiome structure, potentially through the introduction of several hub microbial taxa and by increasing the centralization of the microbial interaction networks. Honey bees were collected from beehives, and common bacterial, fungal and viral honey bee pathogens were screened. The expression levels of several immunity-related genes (defensin-1, lysozyme-like, vitellogenin, glucose oxidase) and the composition of the bee microbiome were examined to assess honey bee health status. Black queen cell virus (BQCV) was detected in almost all individuals, while Vairimorpha pathogens were only partially detected. Paenibacillus larvae, Melissococcus plutonius, Kashmir bee virus (KBV), Acute Bee Paralysis Virus (ABPV), Chronic bee paralysis virus (CBPV), Deformed Wing Virus (DWV), and Sacbrood bee virus (SBV) were not detected in the samples. The data indicated that BQCV and Vairimorpha infections had no significant impact on the expression of immunity-related gene. Since the microbiome composition was assessed at the hive level and BQCV was present in every hive, its potential influence on the microbiome remains to be further clarified. In addition, a bacterial isolate from birch pollen was phenotypically, genotypically, and chemotaxonomically characterized using a polyphasic approach. Based on 16S rRNA gene phylogeny and comparative genomic analysis, the isolate was identified as a novel species of the genus Robbsia. The bacterium was rod-shaped, non-motile, facultative anaerobic and grew optimally at 28 °C and pH 6–7. Unlike its closest relative Robbsia andropogonis, which is a known phytopathogen, the isolate exhibited no phytopathogenic traits such as flagellum formation, rhizobitoxine production, or induction of plant hypersensitive response. The proposed and accepted name of the isolate is Robbsia betulipollinis Bb-Pol-6T.
Multiparametrische MR-Bildgebung als nicht-invasiver Biomarker für Meniskus-Degenerationen beim Hund
(2025) Bunzendahl-Först, Lena
Die Osteoarthrose des Kniegelenkes ist sowohl beim Menschen, als auch beim Hund, unabhändig von der genauen Genese, ein weit verbreitetes Erkrankungsbild. Sie kann je nach Schweregrad zu deutlichen Einschränkungen in der Lebensqualität betroffener Patienten führen. Eine Heilung bzw. das Verhindern des Voranschreitens der Degenerationen ist nach aktuellem Stand nicht möglich. Behoben werden können im Bereich der Tiermedizin mehr oder weniger die auslösenden Faktoren, wie beisielsweise ein vorderer Kreuzbandriss oder eine Patellaluation beim Hund. Das Auftreten einer Osteoarthrose nach einer solchen Gelenkserkrankung zu verhindern, ist jedoch nicht möglich. Aktuelle Therapien können im besten Fall Symptome lindern und das Voranschreiten der Erkrankung verlangsamen. Die Menisken des Kniegelenkes spielen als mandarinenförmige Faserknorpelscheiben eine äußerst wichtige Rolle zur Gesunderhaltung des Gelenkes. Sie gleichen die Inkongruenz zwischen den Gelenkflächen des Femurs und der Tibia aus und minimieren Stoß- und Druckbelastungen. Aufgrund dieser anspruchsvollen mechanischen Funktion sind die Menisken häufig von Degenerationen betroffen. Meniskusschäden entstehen beispielsweise häufig im Zusammenhang mit einer Kreuzbandruptur und sie können das Entstehen bzw. das Ausmaß der Osteoarthrose stark beeinflussen. Daher kommt ihnen im Rahmen wissenschaftlicher Studien zur Pathogenese und Therapie der Arthrose eine wichtige Bedeutung zu. Zur Abklärung von Meniskusschäden ist die MRT v.a. in der Humanmedizin das Mittel der ersten Wahl. Als nicht invasive Technik ermöglicht sie eine sehr gute Darstellung der Menisken. Die konventionelle qualitative MR-Bildgebung weist jedoch Defizite auf, wenn es um die Darstellung mikrostruktureller Veränderungen der Menisken geht. Sie kann nur Pathologien detektieren, die zu morphologischen Veränderungen des Gewebes führen. Da aber gerade im Rahmen der Arthroseentstehung eine frühzeitige Erkennung die besten Aussichten auf eine erfolgreiche Therapie hat, kommen zunehmend MR-Sequenzen zum Einsatz, die (mikro-)strukturelle Veränderungen des Gewebes detektieren können. Auch für andere Anwendungsgebiete, wie z.B. die Überprüfung von verschiedenen therapeutischen Maßnahmen, kann diese Art der Bildgebung sinnvoll sein. Das Ziel dieser Studie war es, die T1-, T2-, T2*-Relaxationszeit und den Magnetisierungsransfer in Form der MTR und des MTsat als Biomarker für frühe Meniskusdegenerationen zu untersuchen. Dazu wurden in einem ex vivo Studiendesign die Menisken älterer Hunde mittels verschiedener MR-Kontraste untersucht. Im Anschluss erfolgte die histologische Untersuchung der Menisken zur Beurteilung von Zellularität, Kollagenorganisation, Kollagen-gehalt und Proteoglykangehalt. In der ersten Studie zur Untersuchung der T2-Relaxationszeit wurden 16 Gelenk von 8 mittelgroßen, älteren Hunden untersucht. Durchgeführt wurden die MRT-Untersuchung der Kniegelenke mit manueller Segmentierung der Menisken und deren anschließender histolgischer Untersuchung. Die T2-Relaxationszeit lag im Mittel bei 18,3ms. Die medialen Menisken wiesen im Mittel eine T2-Relaxationszeit von 17,7ms auf, die lateralen Menisken eine T2-Relaxationszeit von 19,0ms. Wir konnten keinen signifikanten Unterschied zwischen den medialen und lateralen Menisken feststellen. Außerdem fand sich keine Korrelation zwischen T2-Relaxation und Alter und Geschlecht der untersuchten Hunde. In der histologischen Untersuchung fanden wir einen signifikant höheren Degenerationsgrad in den medialen Menisken (Score 4,75 (medial) vs. 3,75 (lateral)). Zwischen den histologischen Ergebnissen und der T2-Relaxations der Menisken konnte keine signifikante Korrelation festgestellt werden. In der zweiten Studie musste aufgrund technischer Fehler ein Gelenk von der Auswertung ausgeschlossen werden. Es wurden somit ingesamt 30 Menisken von 15 Gelenken untersucht. Die Ergebnisse der histologischen Untersuchungen wurden von der vorangegangen Studie übernommen und um einige bildgebenden Parameter (T1, T2*, Magnetisierungstransfer) ergänzt. Auch hier konnten nur vereinzelt Zusammenhänge zwischen histologischen und bildgebenden Parametern gefunden werden. Die T1-Relaxation sank mit steigendem Proteoglykangehalt und stieg mit zunehmender Zellularität an. Die mittlere T1-Relaxation der medialen Menisken lag bei 517ms, die der lateralen Menisken bei 536ms. Die MTsat-Werte waren dahingegen in Menisken mit höherem Proteoglykanscore erhöht. Der Mittelwert von MTsat lag für die medialen Menisken bei 0,08ms und für die lateralen Menisken bei 0,08ms. Der Proteoglykan- und Kollagengehalt zeigten in unseren Ergebnissen einen gegensätzlichen Effekt auf MTsat zu haben. Um dies weitergehend betrachten zu können, wurde zusätzlich das Verhältnis von Kollagen- und Proteoglykanscore gebildet. Dabei zeigte sich, dass MTsat bei höherem „Kollagen-zu-Proteoglykan-Verhältnis“ signifikant niedriger war (p<0,002). Eine Korrelation zwischen dem histologischen Gesamtscore und den einzelnen MR-Parametern konnte auch hier nicht gefunden werden. Bei unabhängiger Analyse der medialen und lateralen Menisken konnte eine leichte negative Korrelation zwischen MTR und dem Histoscore der medialen Menisken gefunden werden. Diese Korrelation ist jedoch nur als Tendenz anzusprechen, da sie keine statistische Signifikanz erreichte (p=0,08). Desweiteren konnte gezeigt werden, dass MTR tendenziell niedriger in den medialen Menisken war (p=0,059). Die histologische Untersuchung der Menisken ergab einen signifikant höhren Proteoglykanscore der medialen Menisken bei zugleich größerer Variabiltät innerhalb der einzelnen Proben (p=0,006). Daraus könnte geschlossen werden, dass MTR indirekt mit dem Proteoglykanscore in Zusammenhang steht. Die Ergebnisse dieser Studien zeigen, dass grundsätzlich geringe histologische Veränderungen in den Menisken älterer, klinisch unauffälliger Hunde nachweisbar sind. Keiner der untersuchten MR-Kontraste wies eine hohe Spezifität oder Sensitivität bezüglich geringgradiger histologischer Meniskusveränderungen auf. Die gezeigten Zusammenhänge von MTsat und T1-Relaxationszeit mit dem Proteoglykangehalt bzw. der Zellularität sprechen dafür, dass einige dieser Parameter vielversprechende Kandidaten sein könnten, um mikrostrukturelle Gewebeveränderungen zu detektieren. Gleichzeitig zeigen die Studien aber auch, dass die Darstellung von geringgradigen Meniskusdegenerationen sehr herausfordernd ist. Die semi-quantitative Bildgebung muss v.a. im Bereich der Tiermedizin erst noch etabliert werden. Sie bietet jedoch grundsätzlich ein hohes Potential für die Früherkennung von strukturellen Meniskusveränderungen und kann somit sowohl in der Forschung als auch in der klinischen Anwendung wertvolle Informationen liefern.
Towards a deeper understanding of genetics of dermatitis digitalis in dairy cows through the consideration of housing characteristics, climate and barn emissions in alternative statistical modelling approaches
(2025) Sölzer, Niklas
Claw disorders are one of the main reasons for the culling of dairy cows. Due to the lameness that often follows in the herd, the feed intake and, not least, the milk yield of the affected animals decrease. These indirect costs are further increased by the also decreasing fertility of affected animals. In addition, there are the direct costs of veterinary treatment, medication and the need for more care of the lame animals. One of the most frequent claw disorders in this area, occurring worldwide, is dermatitis digitalis, usually better known as Mortellaro's disease. Dermatitis digitalis (DD) is a multifactorial disease in which both the housing environment and the genetics of the animals play a role. In recent years, several studies have been published to clarify the genetic background of claw disorders in general and DD in particular. In this context, genome-wide association studies (GWAS) have been conducted and potential candidate genes associated with claw disorders have been annotated. However, it is still unclear how specific environmental effects influence the estimation of variance components and GWAS. Climatic conditions in particular have changed in recent years and will continue to have an increasing impact on the productivity and welfare of cattle in the future. The Temperature-Humidity Index (THI) is a scientifically proven tool in this context. Heat stress (HS) for cattle begins at a THI > 68. The wide availability of data from weather stations near farms enables appropriate management. In order to identify possible correlations with claw health, SNP x heat stress (HS) interactions for claw disorders were analysed in the first part of this study. This showed that specific SNPs and their annotated candidate genes were only significant under HS or thermoneutral conditions. In the second part of this study, the aspect of interaction effects was taken up again. Here, SNP x housing system interactions were estimated for three DD traits in the housing systems of cubicle housing and compost bedded pack barn. However, very similar genetic parameters were found for the same traits in different environments. As well as negligible genotype x housing system interactions. This indicates that the housing system has only a minor effect on the genetic evaluation of a DD disease. Since cattle farming must adapt to the negative consequences of climate change, on the one hand, and is mentioned as a contributor to climate change, on the other, these aspects should also be reflected in the study design. Therefore, on the one hand, climate influences (wind speed, temperature and humidity) were recorded, and on the other hand, the emissions of ammonia, nitrous oxide, carbon dioxide and methane were measured in the barn. A special ‘climate gas trolley’ was built for this purpose. Using this, it was possible to measure the effects of climate and emissions at the same time in different areas of the barn. In the third part of this study, the effects of the housing environment, cow phenotypes and genomics were placed in an overall context. This approach has been used very rarely in animal breeding to date and not at all in relation to a DD disorder. Structural equation modelling (SEM) was used to address this issue. These models can incorporate both measurable and non-measurable variables into the analyses and have mostly been used in psychology until now. In this study, the models allow for the simultaneous consideration of environmental and genetic effects. The SEM showed that the housing environment has a greater influence on DD than genetic parameters, for example. In summary, the results of this study contribute to a better understanding of the genetic background of claw disorders in general and DD in particular. The results also provide an important contribution to a better understanding and further clarification of genotype-environment interactions. To provide a general introduction to the subject of the dissertation, Chapter 1 will take a closer look at the disease DD. On the one hand, the general course of the disease with its clinical symptoms, therapy and prevention is discussed, but on the other hand, economic aspects and the complexity of possible causes of the disease are also mentioned. The following part of the chapter deals with the housing systems of conventional cubicle housing and compost bedded housing. The chapter ends with various possibilities for modelling and the current knowledge on breeding for disease resistance. Chapter 2 aims at a deeper genomic analysis of the three claw disorders DD, hyperplasia interdigitalis (HYP) and Sole ulcer (SU), as well as their genetic association with other important breeding goal traits. Finally, possible SNP x heat stress interactions for claw disorders are analysed. The study design included 17,264 genotyped, first-lactating Holstein Friesian cows from 50 herds in northeast Germany. The heritabilities of the three claw disorders were estimated using linear and threshold models and were 0.04 and 0.08 for DD, 0.03 and 0.10 for SU and 0.03 and 0.23 for HYP. Genetic correlations estimated in bivariate linear models were consistently positive with the selected conformation traits. This indirectly indicates the need for selection on conformation traits to improve claw health. Genetic correlations with other breeding goal traits showed reduced fertility, poorer udder health and productivity in diseased cows. Genetic correlations were observed between the claw disorders, suggesting a closer genetic relationship. Furthermore, disease-specific candidate genes and genetic associations based on the surrounding SNPs were estimated, which in some cases differed from the genetic correlations. For the SNP x heat stress interactions, significant SNPs were identified on BTA 2,4,5,7,8,9,13,22,25 and 28. The results suggest gene-specific mechanisms for claw disorders only in specific environments. In Chapter 3, a detailed phenotypic characterisation of the claw disorder DD in the two housing environments (conventional cubicle barn and compost bedded pack barn) was carried out to determine possible genotype x housing system interactions. In total, the data set comprised 2,980 observations for the three traits DD-sick, DD-acute and DD-chronic from 1,311 Holstein-Friesian and 399 Simmental cows, 926 of these animals were available for the genomic studies. In total 899 cows were housed in the compost bedded pack barn (1,530 observations) and 811 were housed in the conventional cubicle barn (1,450 observations). The disease prevalence was higher in the cubicle barn than in the compost bedded pack barn. The heritabilities over the entire data set were 0.16 for DD-sick, 0.14 for DD-acute and 0.11 for DD-chronic. A slight increase in heritabilities and genetic variances was observed in the housing environment of the cubicle barn compared to the compost bedded pack barn. Genetic correlations between the same DD traits in the different housing environments were close to 0.80, indicating obvious genotype x housing system interactions. The genetic correlations between the three DD traits ranged from 0.58 to 0.81. The SNP main effects and SNP x housing system interactions were estimated using genome-wide association studies. Some common candidate genes were identified for DD-sick and DD-acute. The genes had direct or indirect effects on disease resistance or immunological processes. The genes ASXL1 and NOL4L were annotated for the SNP x housing system interactions for DD-sick and DD-acute. Chapter 4 analyses the effects of the environmental factors, cow phenotypes and genomics in more detail for the DD traits discussed in Chapter 3. The most relevant housing characteristics were analysed in linear models. The last-squares means for the infection probability were generally lower in the compost bedded pack barn than in the cubicle barn. The genome-wide association studies showed similar Manhattan plots for DD-sick and DD-acute and similar potential candidate genes in each case. Five SNPs were significantly associated with either DD-acute and DD-sick or with DD-chronic and DD-sick. These significant SNPs were then related to phenotypic and genetic estimated breeding values for the DD traits, as well as to production data and housing environmental factors in structural equation models. This showed that the housing environment had a greater influence on the risk of DD infection than genetic parameters, for example. Finally, some important aspects of this work are discussed again in chapter 5. In particular, genomic aspects of claw disorders, the influence of the housing environment and the economic weight of claw disorders in the total breeding value are considered here.
New Classes of Radial Basis Functions for Quasi-Interpolation
(2025) Ortmann, Mathis
Radial basis functions (RBFs) are considered an important tool in numerical mathematics for approximating functions based on scattered data. They are often used as an interpolation method. In this process, a system of linear equations has to be solved. The size of the linear system is determined by the number of interpolation points. As the number of interpolation points increases, the solution tends to become numerically unstable, which results in the approximation of the function based on the scattered data becoming inaccurate. One possible approach to avoid this problem is provided by quasi-interpolation using RBFs. Quasi-interpolation is an efficient approximation method that does not require a system of linear equations to be solved. Just like interpolation with RBFs, quasi-interpolation is applied in arbitrary dimensions. Since many problems in industry and science are based on the approximation of scattered data, efficient approximation is regarded as a central task. With a rapidly increasing amount of available data, quasi-interpolation is gaining importance compared to classical interpolation. To compute the quasi-interpolation, a RBF has to be selected in advance. The approximation quality is affected by the selected RBF. The determination of an optimal RBF for a given approximation problem is considered an open research challenge. In this work, two new classes of RBFs are presented that are used to improve approximation by quasi-interpolation. The quality of an approximation is determined by the approximation order. A statement about the approximation order is provided by the Strang and Fix conditions. For their application, the asymptotic behavior of the distributional Fourier transform of the RBF is required. In addition to the two new classes of RBFs, a new class of non-RBFs is also introduced for use in quasi-interpolation. The analysis of approximation orders between RBFs and non-RBFs is fundamentally distinguished, and new approaches for further non-RBFs in quasi-interpolation are opened up. The results are shown to yield excellent convergence properties with low computational effort. The theoretical results presented are verified by numerical examples.
Development of a novel conditional gene expression system in the global pest Drosophila suzukii
(2025) Jaffri, Syeda Azka Sehar
The invasive pest D. suzukii causes significant economic losses to soft fruit crops worldwide. This study aims to improve the Sterile Insect Technique (SIT), an ecofriendly pest management approach, by establishing the Q system in D. suzukii. The Q system provides regulated expression of any gene of interest and it allows the generation of transgenic lines with the ability to induce female-specific lethality. The objectives of this study were to isolate and characterize the endogenous pro-apoptotic and pre-embryonic genes of D. suzukii; to analyze gene expression profiles by RT-qPCR; to test the efficacy of pro-apoptotic genes, and embryonic promoters in S2 cells, both independently and in conjunction with Q system components; and to generate the transgenic D. suzukii strains carrying Q system elements for conditional lethality induction. The results of this study provide insights into the potential of pro-apoptotic genes and early embryonic promoter that can be used in conditional expression systems to control pest populations. Notably, transgenic lines of QUAS (the effector element) were successfully generated. However, the attempts to develop any transgenic lines with QF (the activation factor) were failed in D. suzukii. This may pose a very serious obstacle towards the viability of the Q system in this species.
Chromatic and luminance processing during eye movements in human early visual cortex
(2025) Zhang, Yuan
Human vision is not a passive process. Rather, our visual perception of the world emerges from a dynamic and adaptive interplay between sensory input and motor action, whereby perception continually guides movements, and these movements in turn reshape perceptual experience. Eye movements are essential for acquiring clear visual input in natural viewing. Despite substantial progress in understanding how eye movements are generated, controlled, and functionally organized, fundamental questions remain about how early visual processing is modulated by natural viewing behaviors, and how different types of eye movements influence neural mechanisms encoding color and luminance. This dissertation addresses these questions by combining precise neurophysiological measurement techniques with carefully controlled behavioral paradigms. Our eyes move frequently to keep objects of interest projected onto the fovea for a clear image. Among these movements, saccades are rapid, ballistic shifts of gaze that move the eyes from one location to another, while smooth pursuit keeps a moving target within the foveal region through continuous, slow eye rotations that closely match the target’s speed and direction. When the gaze is relatively stable and directed at a single point, the eye is in a state of fixation. These three types of eye movements are fundamental for acquiring visual information from the environment. Visual scenes are encoded by the L, M, and S cones in the retina and then relayed via three pathways: the magnocellular pathway (L+M, luminance), the parvocellular pathway (L–M, red-green opponency), and the koniocellular pathway (S–[L+M], blue-yellow opponency). These pathways transmit information in parallel up to the primary visual cortex (V1), where their signals are subsequently processed through partially distinct yet interacting cortical circuits (for reviews, see Gegenfurtner, 2003; S. H. C. Hendry & Reid, 2000; Nassi & Callaway, 2009). Given that V1 is the first cortical site where luminance and chromatic signals converge and begin to interact, a key unresolved question is how these signals are modulated by different types of eye movements during natural viewing. To explore the neural mechanisms underlying these processes, this thesis employed steady-state visual evoked potentials (SSVEPs) to track neural responses in the early visual cortex. SSVEPs are brain oscillations elicited by periodic visual stimulation (Adrian & Matthews, 1934; for review, see Norcia et al., 2015), originating primarily from V1 (Di Russo et al., 2007; Müller et al., 1997). SSVEPs possess high temporal resolution and exhibit narrowband spectral responses locked precisely to the stimulation frequency, making them highly resistant to eye movement artifacts (e.g., J. Chen et al., 2017a, 2017b; J. Chen, Valsecchi, et al., 2019). Those properties make SSVEPs a reliable tool for studying visual processing in the human early visual cortex during eye movements. In Study 1, we investigated the effect of chromatic (L–M) adaptation during prolonged fixation. Results showed that SSVEP responses to chromatic stimuli progressively decrease as stimulation duration increased, following an exponential decay with a half-life of approximately 20 seconds. In contrast, responses to luminance stimuli did not show any systematic adaptation. After characterizing this sustained visual adaptation, Study 2 then investigated transient modulations of visual cortical responses induced by saccadic eye movements. Results demonstrated comparable saccadic suppression effects on SSVEP responses to both chromatic (L–M) and luminance stimuli. Further modeling of contrast response functions revealed that saccades selectively reduced response gain without altering contrast gain, suggesting that visual attenuation involves a multiplicative mechanism operating similarly within both the parvocellular and magnocellular pathways. To enhance the quality of SSVEP data, the third study evaluated various EEG referencing methods and introduced the Laplacian reference as an optimal strategy for signal derivation. Results showed that the Laplacian reference significantly improved the signal-to-noise ratio (SNR) and reliability of neural measurements, while also being straightforward to implement across different experimental settings. Taken together, these findings underscore the critical role of eye movements in modulating both luminance and chromatic signals within the early visual cortex. This work demonstrates that perception is dynamically shaped by the continuous interplay between sensory input and oculomotor behavior, offering new insights into how active vision operates under natural viewing conditions.

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