Trapped, Released, Transformed: How Minerals Shape the Cycling of Organic Matter in Soils

Soil organic carbon persistence arises from the intertwined effects of mineral surfaces, microbial activity, and the chemical structure of organic matter, which is further modulated by a soil´s boundary conditions. This dissertation addresses two linked questions: How do minerals govern soil organic matter adsorption and desorption, and how do these organo-mineral interactions feed back on microbial utilization and persistence of mineral-associated organic carbon? To probe these questions, calorimetry was combined with isotope tracing and mineral long-term field exposure studies. Isothermal titration calorimetry provided the first direct thermodynamic quantification of adsorption of organic acids to mineral surface, showing that salicylic acid and citric acids bind exothermically to goethite. Calorimetry adsorption experiments onto goethite with differing lattice defect densities uncovered intensified exothermic binding and a greater loss of entropy on minerals abundant with defects, highlighting that adsorption thermodynamics can differ even for a single mineral type substantially. To connect mineral control of organic matter sorption with its microbial fate, uniformly and carboxyl-radiocarbon labeled monomers were adsorbed onto kaolinite, illite and goethite in a set of batch sorption experiments and incubated in loamy and sandy arable topsoil. Despite strong inner-sphere complexation, a substantial share of ligand-bound carboxyl carbon was mineralized. At the molecular scale, microbial carbon use efficiency (CUE) of mineral-adsorbed monomers rose linearly with desorbability (i.e., the ratio of the amount desorbed to the amount sorbed) across all investigated compounds. Notably, CUE values were consistently lower for monomers bound to goethite than to the clay minerals. Taken together, these findings show that mineral surface properties and sorption-desorption dynamics can redirect metabolic allocation between biomass synthesis and respiratory loss. Recognizing that minerals alter nutrient availability in soil, the dissertations research extended to cover phosphorus dynamics as well. In incubation studies, goethite-amended soil´s strong immobilization of phosphate constrained microbial growth, which channeled metabolism toward higher respiration and lower CUE, while illite did not immobilize phosphorus, resulting in higher CUEs for mineral-adsorbed monomers. Conversely, studying phosphorus transport in forest ecosystems exposed that soil colloids rich in carbon and iron can deliver large quantities of bioavailable phosphorus into sinks mimicking plant roots. This demonstrates that organo-mineral associations can alternate between acting as phosphorus sinks and nutrient shuttles, depending on their saturation state and soil boundary conditions. Laboratory findings on mineral-associated organic matter cycling were further validated under field conditions investigating minerals buried in temperate grassland and forests for five years. Across all sites, goethite accrued nearly four times more carbon than illite, while the proportion of microbial biomass on mineral-associated organic carbon was higher on illite. Notably, carbon-, nitrogen-, and phosphorus-acquiring enzymes were significantly higher on goethite than illite or the surrounding soil, characteristic of microbial mining under nutrient limitations. Three overarching insights emerge. First, the amount of carbon stabilized on mineral surfaces is mineral-specific and further depends on molecular functionality and soil properties such as pH and phosphate accessibility, but no sorption-strength threshold dictates bioaccesibility. Second, microbial processing of mineral-associated organic carbon is inseparable from phosphorus cycling, both of which are mediated by mineral type. Third, oxides and clay minerals both contribute to the persistence of organic carbon, but via contrasting mechanisms. Illite´s nutrient-rich surfaces promote rapid turnover with high CUE that channels carbon into new biomass, whereas goethite traps larger amounts in forms less accessible to microbes, leaving the small bioavailable fraction prone to respiration. Together, these findings refine our understanding of how minerals govern organic matter turnover and nutrient availability in soil: their role is soil specific, affected by pH, nutrient availability, and land use.Deutsche Forschungsgemeinschaft (DFG); ROR-ID:018mejw64Sonstige Drittmittelgeber/-inne

Critical analysis of socio-natural dynamics driven by the agricultural commodity boom: the case of Hass avocado in northern Caldas, Colombia

This explanatory study investigates the expansion of Hass avocado plantations (HAP) and their transformative impact on the socio-natural dynamics in Salamina, Caldas, Colombia. The central research question—Why are Hass avocado plantations expanding and transforming the socio-natural dynamics in the Global South?—is addressed through a systematic approach grounded in interdisciplinary frameworks and methods. To address this overarching question, a robust theoretical framework was first developed to analyze the socio-natural interactions underlying these transformations. The study then employed four sub-questions to explore the issue systematically. The first sub-question examined the phenomenon from a Global South perspective, followed by two sub-questions focusing on the specifics of the Salamina case. The final sub-question recontextualized the findings within the broader global transformations of food systems, offering insights into the dynamics of these changes as part of a larger learning process. This interdisciplinary research is underpinned by Critical Realism, integrating theoretical and conceptual approaches from political ecology, critical resource geography, and critical political economy. A multilevel design was utilized to address the four sub-questions, employing tailored sub-designs for each. The study’s overarching objective was explanatory: not only to elucidate the socio-economic and environmental implications of HAP expansion but also to analyze the socio-historical, economic, and political structures enabling this phenomenon. Methodologically, a mixed-methods approach was employed through a sequential design, balancing qualitative and quantitative data collected and analyzed simultaneously before integration during interpretation. A single cross-sectional explanatory case study further deepened the analysis. Findings reveal a complex landscape of socio-economic and environmental dynamics in Colombia’s HAP sector. While the plantations have driven economic growth and employment in Salamina and Caldas, they have also introduced significant environmental and social challenges. Colombia faces a critical juncture where economic development must align with environmental sustainability and social responsibility. Policymakers, environmental agencies, and the agricultural community must act decisively to achieve this balance, leveraging the economic potential of Hass avocados while safeguarding ecological systems and cultural heritage. The development and enforcement of sustainable public policies will be essential to navigating this multifaceted challenge

Veränderung auditiv-subjektiver und objektiv-apparativer Stimmparameter vor und nach phonochirurgischen Eingriffen bei gutartigen Stimmlippenveränderungen – eine retrospektive Datenerhebung

Das Ziel dieser Arbeit war die, in Anlehnung an das Basis-Protokoll der ELS, multidimensionale Untersuchung der Stimmqualität zur Beurteilung einer Stimmverbesserung nach phonochirurgischer Intervention bei gutartigen Stimmlippenerkrankungen in einem Patientenkollektiv an der HNO-Universitätsklinik in Magdeburg. Hierfür wurden die Daten von 51 Patienten, die sich im Zeitraum von 2014 bis 2020 aufgrund einer Stimmstörung in operativer Behandlung befanden, ausgewertet. Es zeigte sich in der Gesamtgruppe eine signifikante Verbesserung sowohl der objektivapparativen, als auch der auditiv-subjektiven Stimmparameter. In den histologischen Subgruppen konnten für die Reinke-Ödeme und Polypen signifikante Ergebnisse erzielt werden, tendenzielle Verbesserungen zeigten sich auch in den anderen Subgruppen. Folglich scheint die operative Therapie gutartiger Stimmlippenveränderungen mittels Mikrolaryngoskopie nicht nur für den Operateur ein zufriedenstellendes Ergebnis zu erzielen, sondern auch für den Patienten, dessen Leidensdruck gesenkt und Lebensqualität gesteigert werden kann. Ähnliche Ergebnisse konnten auch in anderen Studien gefunden werden, um jedoch eine bessere Vergleichbarkeit zu schaffen, wäre die Vereinheitlichung der Stimmdiagnostik wünschenswert. Bei der epidemiologischen Auswertung des untersuchten Patientenkollektivs zeigten sich Reinke-Ödeme signifikant häufiger bei Frauen, während Polypen häufiger bei Männern zu finden waren. Rauchen als Risikofaktor bei der Entstehung von Reinke-Ödemen konnte bestätigt werden. Zusammenfassend ermöglicht die mikrolaryngoskopische Therapie von benignen Stimmlippenpathologien eine rasche Symptombesserung, wichtig in diesem Zusammenhang ist aber auch die Kontrolle der Risikofaktoren für einen anhaltenden Erfolg

Genetische Konnektivität von Wildschweinen in von der Afrikanischen Schweinepest betroffenen Gebieten

Der Genotyp II des Afrikanische Schweinepestvirus hat Europa noch fest im Griff. Epidemiologisch ist der Seuchenzug durch hohe Virulenz, hohen Letalität und hohe Tenazität bei geringer Kontagiosität geprägt. Die bisherigen Maßnahmen, wie die intensive Suche nach Kadavern, das Reduzieren der Wildschweinpopulation und das Errichten von Zäunen, scheinen die Ausbreitung zwar zu einzudämmen, können sie bislang aber nicht komplett unterbinden. Für eine optimale Kontrolle großflächiger Ausbreitung über Wildschweinpopulationen scheint es wichtig, die Konnektivität der Populationen untereinander zu kennen. Diese Konnektivität sollte in vorliegender Studie anhand der genetischen Differenzierung zwischen den Wildschweinpopulationen im Zielgebiet bestimmt werden. Dafür standen 1262 Wildschweine (davon 389 ASP-positiv) aus 31 Gebieten zur Verfügung. Die Probensammlung und DNA-Analyse erfolgte in Kooperation mit dem FLI, Riems. Die Genotypisierung erfolgte anhand von 12 Mikrosatelliten. Der Austausch zwischen den Populationen wurde auf Basis populationsgenetischer Kenngrößen und Bayes’scher Clusterverfahren bestimmt und quantifiziert. Das wichtigste Ergebnis war eine Differenzierung der nördlichen und südlichen Populationen entlang einer Linie von der Unteren- und Mittelelbe über Berlin und die A11 bis zur polnischen Grenze. In den beiden so getrennten Gebieten wiesen die untersuchten Populationen untereinander eine gute Konnektivität auf, insbesondere im Bereich Mecklenburg-Vorpommerns. Kleinere Barrierewirkungen ergaben sich aber auch innerhalb der südlichen Region. Durch die Kombination der genetischen Charakteristik der Wildschweine und der ASP-Viren konnte gezeigt werden, dass die Ausbrüche entlang der polnischen Grenze immer wieder durch Neueinträge über die Oder erfolgten, während die Ausbreitung parallel zur Oder und Neiße auf deutscher Seite nur eine lokale und untergeordnete Rolle spielte. Die Daten sprechen außerdem dafür, dass die Virusvarianten nicht auf deutscher Seite entstanden, sondern jeweils aus Polen eingetragen worden sind. ASP-Ausbrüche weiter westlich müssen durch direkte Virusverbreitung über den Menschen erfolgt sein. Hinweise auf eine Rolle von Wildschweinen konnten nicht festgestellt werden. Die populationsgenetischen Befunde, die genomischen Virusdaten und die Ausbreitungsdynamik der Viren belegen eine sehr langsame Ausbreitung innerhalb der Gebiete höchster genetischer Konnektivität und sprechen für einen hohen Infektionsdruck über die Oder und Neiße. Gleichzeitig zeigen sie die hohe Wirksamkeit der vor Ort angewandten Kontrollmaßnahmen

Reconstruction of the Sigma0 baryon in Ag+Ag collisions at sqrt(s_NN) =2.55 GeV with HADES

This work presents the experimental reconstruction of the Sigma0 baryon in – with respect to NN interactions – subthreshold Ag+Ag collisions at 1.58 AGeV kinetic beam energy measured with the HADES experiment. At the HADES experiment, which is located at GSI in Darmstadt, Germany, heavy ion collisions at moderate freeze-out temperatures and high baryon chemical potential are measured, analyzed, and evaluated in comparison with the existing data as well as theoretical predictions. This kinetic beam energy corresponds to a center of mass energy of sqrt(s_NN) = 2.55 GeV, which is the Lambda baryon production threshold in NN collisions. With only a small mass difference of Sigma0 to the Lambda baryon of 77 MeV/c^2, Sigma and Lambda baryons are the lightest strangeness containing baryons. Since all quantum numbers of the Sigma0 and the Lambda baryon are identical, their production mechanisms are expected to be very similar. Due to a different spin configuration of the valence quarks inside the Sigma0 , the Sigma0 is slightly more heavy and decays with nearly 100 % branching ratio into Lambda-photon. However, the reconstruction of the low-energy photon is challenging for most detectors, particularly when attempting to concurrently satisfy the requirements of Lambda reconstruction. For the beamtime of the analyzed Ag+Ag collisions, 15 billion events were recorded. The newly installed electromagnetic calorimeter enables photon reconstruction for HADES for the first time without relying on the previously used conversion method. Within the 0-40 % most central events, around 8000 Sigma0 baryons were reconstructed in the Lambda-photon channel with a significance of approximately 10. In addition to the newly installed electromagnetic calorimeter, the RICH was upgraded with newmulti-anode photomultipliers which strongly enhance reconstruction efficiency as well as lepton purity. These advantages were used for feasibility studies in the Lambda-e+e− decay channel. Hints for a signal were found that are consistent with the extracted signal from the Lambda-photon channel, but due to the small statistics, only a significance level of less than 3 was achieved. A full efficiency and acceptance correction was performed with a resulting multiplicity of 0.014 ± 0.002stat. ± 0.004sys. produced Sigma0 per event which corresponds to a Lambda/Sigma0 ratio at freeze-out of 3.2 ± 0.3stat. ± 0.6sys.. This represents the first measurement of this ratio for a subthreshold Sigma0 production in nucleus nucleus collisions. Comparing to the available world data of p+p collisions close to the Sigma0 production threshold, this ratio increases in p+p to values of 30 and higher. Even more, the measured ratio compares well to measurements in p+p far from threshold. This indicates that the NN threshold has no influence on the Sigma0 production for this energy. The Lambda-photon channel result is compared to statistical hadronization model fit as well as to several transport model predictions. The statistical model calculations are in good agreement to our measurement which endorses the possibility of hyperon production in a thermally equilibrated medium. In this case, the freezeout ratio is directly connected to the mass difference of two states with the same quantum numbers, resulting in a temperature estimation of the created matter by only measuring Lambda and Sigma0. From these measurements T=66 MeV is extracted, which compares well with fits of all hadrons with a statistical model

Properties Of Heavy-Light Four-Quark States From Functional Methods

In this work we study the properties – specifically mass spectra and internal structure – of exotic mesons in the charmonium and bottomonium energy regions. Most of these mesons are deemed candidates for four-quark states featuring two heavy and two light quarks. For our calculations, we employ the functional framework of Dyson-Schwinger and Bethe-Salpeter equations (DSEs and BSEs) using a four-quark formulation. We begin by solving the quark DSEs for different quark flavours and calculating mass spectra from several two-body meson and diquark BSEs. These results serve as input for the four-quark BSE, the central object of this work. Using a physically motivated Ansatz, we describe the heavy-light four-quark states in terms of all possible internal two-quark groupings and the attractive and repulsive forces between them. We compare the mass spectra obtained using only the attractive and the attractive plus repulsive components to experimental measurements or theoretical predictions. In this way, we are able to assess the importance of repulsive forces for our description. Furthermore, we are able to investigate the favoured internal structure of the four-quark states by calculating the contribution of each internal component to the total normalization. We observe that the inclusion of the repulsive forces leads to a much better agreement of our calculated mass spectra with the observed experimental spectra for the hidden-charm and hidden-bottom four-quark states. For the open-flavour four-quark states with total spin = 1, the effect of including the repulsive forces is found to be especially significant, rendering our masses for the $T_{bb}^-$, $T_{bb\bar{s}}^-$, $T_{bc}$, $T_{cc}(3875)^+$ in quantitative agreement with predictions from the literature. Regarding the internal structure, we see that most of the investigated hidden-flavour four-quark states are purely dominated by the respective lightest internal heavy-light meson-meson components. The $^{} = 1^{+−}$ , including the 1̄ (3900) and 1̄ (10610), and the 0−+ channel show a very different picture, however, with a strong tendency towards a dominant hadro-quarkonium component. In all cases, the contribution coming from the diquark-antidiquark pairings is almost negligible. For the open-flavour states, we observe an interesting trend when considering the binding energy of the states with respect to the lowest heavy-light meson-meson threshold. For very shallow bound states, e.g., $T_{cc}^+$, $T_{bc}$, the corresponding heavy-light meson-meson component is found to be dominating. However, the deeper the state is bound, e.g., $T_{bb\bar{s}}^-$ and $T_{bb}$ , the stronger the contribution coming from the diquark-antidiquark pairings becomes

Die Rolle von Ceramiden und assoziierten Faktoren in der Bildung von Coronavirus-induzierten replikativen Organellen

RNA viruses have evolved diverse strategies to re-program and exploit host cellular functions and molecules, including cellular lipids, to ensure efficient virus replication and production of infectious virus progeny. A conserved feature of plus-strand RNA virus replication is the formation of membranous microenvironments (replicative organelles, ROs) in virus-infected cells. RO formation is known to be initiated by virus-encoded membrane-associated nonstructural proteins and involves extensive remodeling of host cell membranes. This process is thought to involve cellular enzymes responsible for synthesizing and modifying specific lipids. In this study, I investigated the potential roles of specific cellular sphingolipids and enzymes acting on sphingolipids in the replication of different coronaviruses. The data revealed that, following infection, cellular ceramide species increase significantly, whereas sphingomyelin levels decreased, indicating an involvement of sphingomyelinases that convert sphingomyelin to ceramide. To verify this, I targeted the cellular sphingomyelinases using pharmacological and genetic approaches. I could provide evidence that neutral sphingomyelinase 2 (nSMase2) plays an essential role in an early phase (but not entry) of coronavirus replication in Huh-7-ACE2 cells. Furthermore, I was able to demonstrate a colocalization of neutral sphingomyelinase 2 and ceramide, but not sphingomyelin, with both infection-induced and genetically induced ROs. Ceramides and coronaviral ROs were found to colocalize in different cell systems used in this study. However, in another set of experiments, I also obtained data to suggest that the extent of specific sphingolipid deregulations and the role of nSMase2 in coronavirus infections may vary among different infection systems, depending on the cell type used. Taken together, this study strongly suggests that ceramides serve as crucial lipid building blocks in the formation of coronaviral ROs in different cell types, suggesting that inhibition of cellular ceramide production may represent a potential antiviral strategy against coronavirus infections. However, the mechanisms of ceramide generation or recruitment to specific intracellular sites seem to vary depending on the cell type used and, possibly, the baseline ceramide levels in these cell types. Further investigation is required to clarify these variations and their biological implications.Deutsche Forschungsgemeinschaft (DFG); ROR-ID:018mejw6

Das Symbol des Schlüssels in zeitgenössischen Kunstwerken und seine Rezeption in der frühkindlichen Bildung - eine Analyse ästhetischen Verhaltens zwischen deutschen und arabisch-israelischen Kindern

Die Dissertation untersucht, wie Kinder im frühen Alter symbolische Bedeutungsträger – insbesondere den Schlüssel – im Rahmen ästhetischer Bildungsprozesse wahrnehmen, deuten und gestalten. Auf der Grundlage einer qualitativ-empirischen Feldstudie mit bi-nationalem Vergleich (Deutschland – Israel) wird gezeigt, dass ästhetische Rezeptionsprozesse, insbesondere die Auseinandersetzung mit Kunstwerken und Objekten der materiellen Kultur, zu narrativen, körperlichen, sozialen und kulturell geprägten Ausdrucksformen führen. Die Ergebnisse zeigen, dass Kinder über symbolisches Verstehen, kreatives Gestalten und emotional-soziale Interaktionen eine tiefgreifende Form der Weltaneignung realisieren. Dabei sind sowohl universelle Aspekte wie Forschergeist (Neugier) und Selbstverortung erkennbar als auch kultur- und bildungssystemspezifische Unterschiede in Ausdrucksverhalten, im Symbolverständnis sowie im Umgang mit Kunst und Dingen. Der Schlüssel fungiert hierbei als zentrales Symbol für Zugang, Erinnerung und Identität. Die Studie leistet einen Beitrag zur Theoriebildung im Bereich der ästhetisch-kulturellen Bildung, der Symbolforschung und der materiellen Kultur in der frühen Kindheit und eröffnet neue Perspektiven für interkulturelle Bildungsprozesse

uniforum 38 (2025) Nr. 3

Wie sieht eine Allianz für Demokratie aus? Wie stellt sich die JLU für die Zukunft auf? Wie LOEWEnstark ist gemeinsame Forschung und wie breit sind die Themen gefächert? Wie wurde Gießen einst eine Brücke zur Freiheit und wie sind Studierende heute im Lern- und Erinnerungsort Notaufnahmelager aktiv? Wie überzeugen zwei Lehramtsstudentinnen mit einem Planspiel zum Thema One Health im Biologieunterricht? Diese und viele weitere Informationen rund um Ereignisse und Entwicklungen an der JLU lesen Sie in der aktuellen Ausgabe des uniforum

Farmers’ Adaptation Behavior to Climate Change: The Case of Central Colombia

Climate change poses significant challenges to agriculture, particularly for small-scale farmers who must continuously adapt to changing conditions to ensure food security and reduce rural poverty. These issues are especially critical in central Colombia, a region located between the Central and Western Andes Mountain ranges, where historical data indicate a rising frequency of extreme weather events, such as landslides and droughts, that affect rural livelihoods. Although the literature on adaptation to climate change has increased in recent years, to the best of our knowledge, there is not an integrated approach to studying farmers’ adaptive behavior in central Colombia. This thesis bridges this gap by systematically examining all the drivers of adaptive behavior and focusing on the financial, experiential, and cognitive factors that shape farmers’ adaptation decisions, using a three-step analytical approach. First, a Systematic Literature Review (SLR) was conducted to identify the key factors of adaptation decisions. A total of 179 drivers were identified and categorized by type, leading to the development of the Farmer-Farm-Financial-Situational-Experiential-Cognitive (3F-SEC) framework, which was published in the first article of this cumulative thesis titled “Drivers of farmers’ adaptive behavior to climate change: The 3F-SEC framework”. This framework provided the basis for studying the adaptive behavior of farmers in central Colombia across three types of drivers: financial, experiential, and cognitive. Given this, a mixed-method approach was designed to analyze the different aspects of farmers’ adaptive behavior, forming the empirical foundation for the second and third articles. A total of 12 villages were selected, with a sample of 360 farmers that were visited between November 2022 and March 2023. The research locations were selected according to their exposure to weather shocks: four villages that experienced landslides, four with recurrent droughts, and four with no reported events as reference villages. A structured questionnaire was administered alongside in-depth interviews with some of the farmers, allowing for a comprehensive understanding of the factors shaping their adaptation decisions. The second article, titled “The Role of Financial Literacy in Climate Mitigation: The Case of Central Colombia,” employs a mixed-methods approach, combining logit models with qualitative data from interviews. It examines farmers’ financial decisions in response to weather shocks, with a particular focus on the role of financial literacy in borrowing behavior. The findings reveal that financially literate farmers are more likely to seek loans following weather shocks. However, informal lending sources remained the dominant financial strategy due to easier access and distrust of formal financial institutions. The third article, titled “Farmers’ Climate Change Perceptions in Central Colombia: A Propensity Score Matching Approach Using Protection Motivation Theory and Psychological Distance,” compares farmers living in droughts and landslide-prone villages, assesses how direct exposure to these events influences climate change perceptions. The findings indicate that droughts significantly increased farmers’ awareness of climate change severity and vulnerability, while landslides had a more limited effect. Taken together, the findings of this thesis highlight the relevance of considering multiple behavioral drivers when analyzing adaptation decisions. From a policy perspective, adopting an integrated approach that considers different behavioral drivers may offer a more comprehensive understanding of farmers’ adaptative capacity to climate change. If the goal is to improve farmers’ access to formal credit, strengthening tailored financial literacy programs may help farmers navigate borrowing decisions. Similarly, integrating localized climate data into training on sustainable agricultural practices could support more informed decision-making, particularly in drought-prone regions. Additionally, communication strategies that draw on farmers’ direct experiences with extreme weather events may reinforce climate risk awareness. Ultimately, adopting a broader perspective that accounts for financial, experiential, and cognitive drivers can provide deeper insights into the complexities of farmers’ adaptive behavior in the face of climate change.Other third-party funder