OPUS documents https://ubt.opus.hbz-nrw.de/index/index/ Thu, 16 Apr 2026 15:49:11 +0200 Thu, 16 Apr 2026 15:49:11 +0200 https://ubt.opus.hbz-nrw.de/frontdoor/index/index/docId/2820 Sea-ice leads play a key role in the climate system by facilitating heat and moisture exchanges between the ocean and atmosphere, as well as by providing essential habitats for marine life. This study presents new insights from a gap-filled monthly dataset on sea-ice leads in the Southern Ocean and a first comprehensive analysis of spatial patterns, seasonal variability, and long-term trends of wintertime (April to September) sea-ice leads over a 21-year period (2003–2023). Our findings reveal that leads are ubiquitous in the Southern Ocean and show distinct spatial patterns with maximum lead frequencies close to the coastline, over the shelf break, and close to seafloor ridges and peaks. We see a strong seasonal variability in lead occurrence, with lead frequencies peaking in mid-winter. Weak but significant trends in lead frequencies are shown for the presented period for individual regions and months. Rather small changes in lead occurrence over the 21 years suggest stable wintertime sea-ice compactness despite the observed strong fluctuations and recent anomalies in sea-ice extent. Expanding upon previous work of lead detection in Antarctic sea ice, this study provides first results on the long-term regional, seasonal, and inter-annual variability of sea-ice leads in the Southern Ocean and can thereby contribute to an improved understanding of air–sea-ice–ocean interactions in the climate system. It also underscores the need for further investigation into the individual contributions of atmospheric and oceanic drivers to sea-ice lead formation in the Antarctic. Sascha Willmes article https://ubt.opus.hbz-nrw.de/frontdoor/index/index/docId/2820 Thu, 16 Apr 2026 15:49:11 +0200 https://ubt.opus.hbz-nrw.de/frontdoor/index/index/docId/2779 Dieser Band enthält die schriftlichen Fassungen der Vorträge, die im Rahmen der Tagung „Wege zu einem starken und lebendigen Föderalismus“ gehalten wurden. Den Anlass für diese Veranstaltung bot das 25-jährige Jubiläum des Instituts für Rechtspolitik an der Universität Trier. Frank Decker; Peter M. Huber article https://ubt.opus.hbz-nrw.de/frontdoor/index/index/docId/2779 Thu, 09 Apr 2026 10:39:05 +0200 https://ubt.opus.hbz-nrw.de/frontdoor/index/index/docId/2801 Price indices play a vital role in economic measurement as they reflect price levels and measure price fluctuations. Price level measures are used with macroeconomic indicators to express them in real terms. These measures are also used to index wages, rents, and pensions. Furthermore, they are used as a reference for monetary policy conducted by central banks. Therefore, the provision of accurate price indices is one of the most important goals of National Statistical Institutes (NSIs), and numerous studies have been devoted to this goal. This cumulative dissertation also contributes to this goal. It contains four chapters, each of which represents a separate research. The first two studies are devoted to the treatment of seasonal products by using different price index methods. The first research is co-authored with Ken van Loon. The third research is dedicated to finding the most accurate method to make price predictions for missing products. The fourth research is focused on the treatment of products by using different price index methods when products’ quality characteristics are available. Botir Radjabov doctoralthesis https://ubt.opus.hbz-nrw.de/frontdoor/index/index/docId/2801 Fri, 30 Jan 2026 11:38:48 +0100 https://ubt.opus.hbz-nrw.de/frontdoor/index/index/docId/2765 Shoko Kariya article https://ubt.opus.hbz-nrw.de/frontdoor/index/index/docId/2765 Tue, 27 Jan 2026 11:29:04 +0100 https://ubt.opus.hbz-nrw.de/frontdoor/index/index/docId/2764 Yuho Hisayama article https://ubt.opus.hbz-nrw.de/frontdoor/index/index/docId/2764 Tue, 27 Jan 2026 11:28:30 +0100 https://ubt.opus.hbz-nrw.de/frontdoor/index/index/docId/2763 Harald Schwaetzer article https://ubt.opus.hbz-nrw.de/frontdoor/index/index/docId/2763 Tue, 27 Jan 2026 11:27:39 +0100 https://ubt.opus.hbz-nrw.de/frontdoor/index/index/docId/2762 Kazuhiko Yamaki article https://ubt.opus.hbz-nrw.de/frontdoor/index/index/docId/2762 Tue, 27 Jan 2026 11:26:39 +0100 https://ubt.opus.hbz-nrw.de/frontdoor/index/index/docId/2761 Pilar Bücker article https://ubt.opus.hbz-nrw.de/frontdoor/index/index/docId/2761 Tue, 27 Jan 2026 11:25:59 +0100 https://ubt.opus.hbz-nrw.de/frontdoor/index/index/docId/2760 Harald Schwaetzer article https://ubt.opus.hbz-nrw.de/frontdoor/index/index/docId/2760 Tue, 27 Jan 2026 11:25:24 +0100 https://ubt.opus.hbz-nrw.de/frontdoor/index/index/docId/2759 Der deutsch-japanische Band widmet sich dem in der neuen Phänomenologie, vor allem bei Schmitz und Böhme, diskutierten Begriff der Atmosphäre. Anders als die meisten eher systematisch orientierten Ansätze wählt der Band einen historischen Zugang. Dass historische Wurzeln bei Goethe liegen, mit dem Schmitz wie Böhme sich intensiv beschäftigt haben, ist bekannt. Bislang ist aber der Frage nach der Geschichte des Atmosphären-Begriffs und seiner Vorläufer wenig Aufmerksamkeit geschenkt worden. Der Band unternimmt es deswegen, eine Linie zu verfolgen, die von Goethe (Hisayama) und Novalis (Kariya) zu Kepler (Schwaetzer), der für beide eine wichtige Referenz war, und von da aus zu Nikolaus von Kues (Yamaki) und dessen Situierung in Mittelalter und Antike (Bücker) zurückgeht. Er will mit diesem exemplarischen historischen Zugang die systematische Fruchtbarkeit einer geistesgeschichtlichen Perspektive für die Entwicklung einer Philosophie der Atmosphäre zeigen. periodicalpart https://ubt.opus.hbz-nrw.de/frontdoor/index/index/docId/2759 Tue, 27 Jan 2026 10:18:48 +0100 https://ubt.opus.hbz-nrw.de/frontdoor/index/index/docId/2594 Dieter Lamping article https://ubt.opus.hbz-nrw.de/frontdoor/index/index/docId/2594 Mon, 26 Jan 2026 07:29:16 +0100 https://ubt.opus.hbz-nrw.de/frontdoor/index/index/docId/2785 Measuring the economic activity of a country requires high-quality data of businesses. In the case of Germany, this is not only required at national level, but also at federal state level and for different economic sectors. Important sources for high-quality business data are the business register and, among others, also 14 business surveys which are conducted by the Federal Statistical Office of Germany. However, the quality requirements of the Federal Statistical Office are in contrast to the interests of the businesses themselves. For them, answering to a survey's questionnaire is an additional cost factor, also known as response burden. A high response burden should be avoided, since it can have a negative impact on the quality of the businesses' responses to the surveys. Therefore, sample coordination can be used as a method to control the distribution of response burden while securing high-quality data. When applying already existing business survey coordination systems, developed by different statistical institutes, legal and administrative standards of German official statistics have to be taken into account. These standards consider different sampling fractions, rotation fractions, periodicity, and stratification of the aforementioned 14 business surveys. Therefore, the aim of this doctoral thesis is to check the existing business survey coordination systems for their applicability in the context of German official statistics and, if necessary, to modify them accordingly. These modifications include the introduction of individual burden indicators which aim to take the individual perception of response burden into account. For this purpose, several synthetic data sets have been created to test the application of the modified versions of the different business survey coordination systems through Monte Carlo simulation studies. These data sets include a large panel data set, reflecting the landscape of businesses in Rhineland-Palatinate and three smaller, synthetic data sets. The latter have been created with the help of the R package BuSuCo which has been developed within the scope of this thesis. The above mentioned simulation studies are evaluated based on different measures for estimation quality as well as for the concentration and distribution of response burden. Johannes Straubinger doctoralthesis https://ubt.opus.hbz-nrw.de/frontdoor/index/index/docId/2785 Thu, 18 Dec 2025 10:26:12 +0100 https://ubt.opus.hbz-nrw.de/frontdoor/index/index/docId/2786 Bilevel problems are optimization problems for which parts of the variables are constrained to be an optimal solution to another nested optimization problem. This structure renders bilevel problems particularly well-suited for modeling hierarchical decision-making processes. They are widely applicable in areas such as energy markets, transportation systems, security planning, and pricing. However, the hierarchical nature of these problems also makes them inherently challenging to solve, both in theory and in practice. In this thesis, we study different nonlinear problem settings for the nested optimization problem. First, we focus on nonlinear but convex bilevel problems with purely integer variables. We propose a solution algorithm that uses a branch-and-cut framework with tailored cutting planes. We prove correctness and finite termination of the method under suitable assumptions and put it into context of existing literature. Moreover, we provide an extensive numerical study to showcase the applicability of our method and we compare it to the state-of-the-art approach for a less general setting on suitable instances from the literature. Furthermore, we discuss challenges that arise when we try to generalize our approach to the mixed-integer setting. Next, we study mixed-integer bilevel problems for which the nested problem has a nonconvex and quadratic objective function, linear constraints, and continuous variables. We state and prove a complexity-theoretical hardness result for this problem class and develop a lower and upper bounding scheme to solve these problems. We prove correctness and finite termination of the proposed method under suitable assumptions and test its applicability in a numerical study. Finally, we consider bilevel problems with continuous variables, where the nested problem has a convex-quadratic objective function and linear constraints. We reformulate them as single-level optimization problems using necessary and sufficient optimality conditions for the nested problem. Then, we explore the family of so-called P-split reformulations for this single-level problem and test their applicability in a preliminary numerical study. Andreas Horländer doctoralthesis https://ubt.opus.hbz-nrw.de/frontdoor/index/index/docId/2786 Thu, 18 Dec 2025 10:25:20 +0100 https://ubt.opus.hbz-nrw.de/frontdoor/index/index/docId/2776 Die Arbeit untersucht den bundesdeutschen Diskurs zur europäischen Integration seit 1990 aus diskurslinguistischer Perspektive und versteht ihn als Aushandlungsraum europäischer Identitätskonstruktionen. Ausgangspunkt ist die Annahme, dass institutionelle Vertiefung und geografische Erweiterung der EU nicht allein als verrechtlichte Integrationsschritte zu begreifen sind, sondern stets auch identitätspolitische Dimensionen tragen. Ziel der Studie ist es, die sprachliche Konstituierung der EU als identitätspolitisches Referenzsystem sichtbar zu machen und damit eine diskurslinguistische Ergänzung zur interdisziplinären Integrationsforschung zu leisten. Auf Grundlage eines diachronen Korpus, das zentrale integrationspolitische Etappen und Krisenphasen umfasst, wird ein Mixed-Methods-Ansatz entwickelt, der korpusgeleitete Verfahren mit der hermeneutischen Annotation diskurslinguistischer Kategorien verbindet. Analysiert werden nicht nur lexikalisch-semantische Repräsentationen Europas, sondern vor allem diskursive Grundfiguren wie Einheit, Vielfalt, Eigenes und Fremdes sowie deren Verbindung zu politischen Sinnzuschreibungen. Die Ergebnisse zeigen, in welchem Maße sich im deutschen Diskurs ein stabiler identitätspolitischer Bezugspunkt zur EU herausgebildet hat, wie sich normative Leitbilder und funktionale Rationalitäten überlagern und wie europäische Integration sprachlich zwischen symbolischer Aufladung und strategischer Instrumentalisierung verhandelt wird. Erik Schröder doctoralthesis https://ubt.opus.hbz-nrw.de/frontdoor/index/index/docId/2776 Mon, 15 Dec 2025 13:56:31 +0100 https://ubt.opus.hbz-nrw.de/frontdoor/index/index/docId/2782 Extracellular enzymes in microbial communities play a central role in nutrient cycling and the degradation of (pollutant) substances in various natural and anthropogenic systems. Bound in aquatic biofilms, sludge aggregates, or even unbound at their interfaces, they are of great importance for both the environment and human health. In particular, in wastewater treatment plants and inland waters, hydrolytic activities influence the wide-reaching efficiency of nutrient removal and self-purification, thus contributing significantly to overall water quality. The main goal of this dissertation project was to investigate the factors that influence enzymatic activity and the health of microbial communities in activated sludge and river systems, particularly in relation to anthropogenic influences and natural environmental conditions. The aim was to contribute to a better understanding of the sensitivity of our freshwater ecosystems and to support the long-term preservation of water quality and ecological stability. The development and optimization of appropriate methods, as well as their testing and applicability, were the focal points. For this purpose, a fluorometric microplate assay was developed and adapted to determine both extracellular enzyme activities (EEAs) in activated sludge samples and in intact biofilms. Its suitability for field studies was subsequently tested. Inhibition and activity of selected hydrolases under different conditions were investigated to better understand the mechanisms and potential environmental risks posed by anthropogenic influences and seasonal fluctuations of hydrochemical and climatic parameters. The first phase of the doctoral thesis involved studies on the inhibition of alkaline phosphatase in activated sludge by oxyanions. Using the fluorometric microplate assay, the inhibitory effect was sensitively detected over a pH range of 7.0 to 8.5. IC50- and IC20-concentrations were calculated from modeled dose-response functions. It was found that vanadate and tungstate caused strong inhibitory effects, while molybdate moderately inhibited the enzyme. An increasing pH led to a reduction in the inhibitory effect of tungstate and molybdate. The inhibition effects of vanadate were not significantly affected by the pH. In municipal wastewater, the concentrations of such metal ions are usually low, but industrial wastewater may have pollutant loads that can significantly impact the removal of phosphorus-containing compounds, and thus the efficiency of treatment plants. In the second phase, an attempt was made to further adapt the developed methodology to investigate EEA and kinetics in intact freshwater biofilms. Four different types of bead materials (lava, glass, sintered quartz, and ceramics) fitting into a 96-well microplate were tested as carriers for biofilms on both the laboratory and field scale. The analysis included a total of seven hydrolases as representatives of key nutrient cycles such as phosphorus, carbon, and nitrogen: phosphatases, glucosidases, peptidases (two different types), and sulfatase. Experiments with increasing substrate concentrations led to classical kinetic profiles according to the Michaelis-Menten mechanism. This allowed for the prediction of the biofilm enzymes’ response to different substrate concentrations. Parameters such as Vmax and Km could be derived from the modeled curves. Ceramic beads are particularly suitable for long-term studies due to their high stability, while sintered quartz beads should be preferred for the use in stagnant media (material loss under turbulent conditions). Lava and glass beads, on the other and, proved suboptimal for uniform biofilm development due to their surface properties. The potential use of this fast and sensitive test for ecotoxicological or even human-toxicological studies was demonstrated by the effects of caffeine on the activity of PDE. The result of this part of the research represents a powerful tool for assessing environmental pollution and monitoring water quality. The high application potential was clearly highlighted in the final phase of the project. The goal here was to deepen the understanding of interactions between seasonal factors, anthropogenic influences, and biofilm processes in rivers by investigating EEA and biofilm parameters such as biomass and relating them to hydrochemical and climatic factors. Ceramic beads were exposed both upstream and downstream of a wastewater treatment plant discharge and sampled over a period of seven months. EEAs and biomass varied depending on the season and location, with higher microbial activity observed upstream in winter. Winter conditions led to the dilution of most nutrients as well as in an increse of dissolved oxygen. Nutrient concentrations analyzed downstream were significantly higher in the summer. Accumulation of nutrient or pollutants during the summer months cannot be excluded, which may have led to a general reduction in enzyme activities. Potential causes could be inhibitory effects on the enzymes, or a reduced enzyme activity due to a sufficiently high nutrient supply. In general, the sampling site upstream showed a more pronounced seasonal dynamics, with a significant proportion of the variance in biological parameters (activity and biomass) attributable to seasonal factors. A secondary component, likely reflecting the impact of the treatment plant discharge, explained another portion of the data variance. Regardless of the season, high correlations between biological parameters were observed upstream, while downstream the data were more decorrelated. This could be because the biofilms, under chronic stress, respond less dynamically to seasonal fluctuations. This dissertation illustrates that in addition to anthropogenic stress factors, seasonal fluctuations of hydrochemical and climatic parameters should also be considered in "stress downstream the pipe" studies. The selected methods are recommended for explaining and considering the data variance, as they highlight the complex interplay between microbial enzymatic activity, environmental factors, and pollutants in the activated sludge of wastewater treatment plants and also in aquatic systems. The novel bead assay could pave the way for the future standardization of effect-oriented studies on intact aquatic biofilms. Maria Riese doctoralthesis https://ubt.opus.hbz-nrw.de/frontdoor/index/index/docId/2782 Mon, 15 Dec 2025 13:36:28 +0100 https://ubt.opus.hbz-nrw.de/frontdoor/index/index/docId/2599 Perennial crops eliminate soil disturbance and reduce the amount of synthetic chemicals that are applied to the soil, improving soil biodiversity and food web structure. Additionally, perennial cropping is characterised by all year-round surface coverage which benefits soil biota in terms of habitat and food sources. Perennial intermediate wheatgrass (Thinopyrum intermedium, IWG) was domesticated and commercialised by The Land Institute in Kansas as Kernza® and serves as an example for these nature-based solutions. It develops an extensive root system that has a higher nutrient retention, possibly reducing nutrient runoff. It thereby follows a more resource-conservative strategy with improved belowground-oriented resource allocation in its root system. This may reduce the need for excessive fertiliser as the crop has a higher nitrogen efficiency, among other things. IWG promoted the earthworm community and its diversity, more specifically, the occurrence of epigeic species (litter inhabitants), since those species benefit from the increased soil coverage and elimination of disturbances in the soil. As IWG creates a dense and extensive root system, as shown by the increased occurrence of root-feeding nematodes, endogeic species (horizontal burrowers) are supported through the provision of a reliable food source. IWG was characterised as a mostly undisturbed system with a highly structured food web through nematode analysis, as expressed through the promotion of structure indicators, for example, that are sensitive to disturbances in the soil and are therefore supported under no-till management. The root microbiome is continuously being shaped by the host as the crop regrows from the roots each vegetation period. This creates a symbiotic relationship and a beneficial feedback loop for the crop. Resultantly, the root-endophytic microbiome under IWG had a higher network complexity, connectivity and stability compared to annual wheat. The regrowth from the roots for IWG requires increased nutrient and energy storage, which was indicated by increased starch values. Correspondingly, the longer residence time of the roots in the soil resulted in higher lignin values. Furthermore, the decomposition pathway was dominated by fungivorous nematodes which may correspond to stimulated nutrient cycling and a heterogeneous resource environment, as seen for low input systems. Overall, perennial wheat cultivation improved soil biodiversity already after an establishment of 3-6 years. As those benefits were present for all three countries, the varying soil and climate conditions do not seem to interfere with the positive effect of perennial wheat on the soil ecosystem, demonstrating a wide transferability and adaptability of the crop onto other study sites as well. Enhanced complexity and connectivity of the food web in comparison to annual wheat may indicate a resistance against abiotic stress, suggesting IWG cultivation as a viable option for a sustainable and resilient agriculture. The improvement in nutrient cycling and the resource-efficient cultivation strategy for IWG could enable cultivation on marginal land where annual crop cultivation is not possible as the soils are susceptible to erosion and nutrient runoff. This opens up new possibilities for agricultural cultivation on previously unused land, thus contributing to food security in the future. Alena Förster doctoralthesis https://ubt.opus.hbz-nrw.de/frontdoor/index/index/docId/2599 Mon, 15 Dec 2025 08:07:36 +0100 https://ubt.opus.hbz-nrw.de/frontdoor/index/index/docId/2774 The application of machine learning and deep learning methods to hydrological modelling has advanced significantly in recent years, offering alternatives to traditional conceptual and physically based approaches. Within the numerous algorithms, long short-term memory (LSTM) networks have proven themselves particularly useful for the task of streamflow modelling. This thesis provides a collection of publications that investigate the capabilities, limitations and interpretability of LSTM for the purpose of streamflow modelling and climate change impact assessment within the lowland Ems catchment in Northwest Germany. Within a comparative performance evaluation, LSTM and its predecessor, the recurrent neural network, demonstrate superior accuracy compared to the conceptual HBV model across various statistical performance metrics. However, a decline in performance was observed during low-flow conditions in certain sub-catchments. The evaluation of the flow duration curve revealed that the ML models more effectively capture the water balance, while HBV better represents streamflow dynamics. To enhance the interpretability of LSTM, six explainable artificial intelligence techniques were applied. These methods consistently identified seasonal patterns in the temporal relevance of hydroclimatic input data. In combination with an observed correlation between the internal LSTM states and catchment-scale soil moisture dynamics, the findings suggest that LSTM models are capable of implicitly learning the relevant hydrological processes. Following, the capabilities of LSTM to model climate change impact scenarios, particularly when they extend beyond historically observed climate conditions, are addressed. An ensemble of climate change projections is provided as hydroclimatic input to evaluate the performance of LSTMs and conceptual models. While all models reveal heterogeneous alterations in streamflow under future climate conditions, significant differences emerge based on the model type. Results provide evidence that LSTMs, in combination with the temperature-based Haude formula for estimating potential evaporation, work inadequately under altered climatic regimes, raising concerns about their applicability in long-term projections. The study also indicates the potential need to incorporate physical constraints into LSTM architectures to ensure model robustness and hydrological plausibility beyond the historical training range. Collectively, this thesis contributes important insights into the applicability and interpretability of LSTM models in streamflow modelling. Despite the presence of a physically realistic representation of soil moisture dynamics of the Ems catchment, no robust change signals for streamflow under climate change can be derived. Those results underscore the potential of LSTM model approaches for accurate streamflow simulation, however, they require us to always critically question LSTM results, particularly when they are applied outside the training range. Alexander Ley-Lützenkirchen doctoralthesis https://ubt.opus.hbz-nrw.de/frontdoor/index/index/docId/2774 Wed, 10 Dec 2025 11:30:32 +0100 https://ubt.opus.hbz-nrw.de/frontdoor/index/index/docId/2780 Die Verfügbarkeit von ortho-Phosphat (o-PO₄) trägt wesentlich zur Eutrophierung von Fließgewässern bei und gefährdet damit das Erreichen des „guten ökologischen Zustands“ gemäß der EU-Wasserrahmenrichtlinie. Da die kommunalen Kläranlagen zentrale Eintragsquellen darstellen, gewinnt die Reduktion von o-PO₄ an dieser Stelle an Bedeutung. Neben der chemischen Phosphorelimination bietet insbesondere die vierte Reinigungsstufe, primär zur Entfernung von Mikroschadstoffen konzipiert, einen Synergieeffekt mit potenziellen Phosphorentfernungsraten von bis zu 85 %. Zur Bewertung des Einflusses einer solchen Reinigungsstufe wurde ein Modell für ausgewählte saarländische Oberflächenwasserkörper (OWK) entwickelt, das den Trockenwetterfall als eutrophierungsrelevantes Szenario abbildet. Ein zentraler Bestandteil ist ein neu erarbeiteter Retentionsansatz, der biochemische und physikalische Prozesse wie Adsorption, Sedimentation und biologische Assimilation berücksichtigt. Auf Basis der Differenz zwischen emissionsseitig bilanziertem und gemessenem o-PO₄-Gehalt wurden für jeden OWK Verminderungsraten je Fließmeter abgeleitet und schließlich eine Gleichung zur Abschätzung der Retention in Abhängigkeit der Einzugsgebietsgröße formuliert. Die Validierung zeigt hinreichende Modellgenauigkeit, wenngleich negative Frachtdifferenzen in einigen Gewässern auf zusätzliche, nicht eindeutig quantifizierbare Einträge – etwa aus Landwirtschaft oder Kanalverlusten – hindeuten. Die Szenarienanalyse belegt, dass eine vierte Reinigungsstufe grundsätzlich zur Reduktion von o-PO₄ an den Messstellen beiträgt. Eine Unterschreitung des geltenden Orientierungswertes wird jedoch nur erreicht, wenn sämtliche Kläranlagen eines OWK nachgerüstet werden – und auch dann nur in einigen Fällen. Damit stellt die vierte Reinigungsstufe allein keine ausreichende Alternative zu den Maßnahmen des 3. Bewirtschaftungsplans des Saarlandes dar, kann jedoch als ergänzende Strategie zur Verringerung der Phosphoreinträge dienen. Nicolas Stoffels doctoralthesis https://ubt.opus.hbz-nrw.de/frontdoor/index/index/docId/2780 Wed, 10 Dec 2025 10:53:38 +0100 https://ubt.opus.hbz-nrw.de/frontdoor/index/index/docId/2773 Present-day air quality is known through dense monitoring and extensive pollu- tion control mechanisms. In contrast, knowledge of historical pollution, particularly before the industrial revolution, is accessible only through occasional reports of singular local events and through natural archives such as ice or sediment cores that record global-scale pollution. However, the regular local to regional pollution that most affects human life is hardly known. Historical sciences have argued both for and against significant air pollution in and around historic cities and manufacturing sites. For the Roman era, it has been hypothesized that air quality played a role in several patterns of action of the period. However, to the author's knowledge, there are no quantitative studies of Roman emissions. Using the results of modern experimental archaeology, this study attempts to quantify the emissions from Roman pottery kilns and their impact on surrounding human settlements. It is shown that although the pollution did not reach today's limits, it must have approached levels known to cause adverse health effects. A series of additional test simulations have been conducted to determine how these first results might be improved in the future. Clemens Drüe article https://ubt.opus.hbz-nrw.de/frontdoor/index/index/docId/2773 Mon, 01 Dec 2025 10:26:05 +0100 https://ubt.opus.hbz-nrw.de/frontdoor/index/index/docId/2767 Spatial microsimulation is an important tool for integrating geographical information into the evaluation of public policies and the analysis of social phenomena in urban regions. These models simulate the behavior and interaction between units of the region, such as individuals, households or firms, under specific conditions that may or not involve projections over time. This requires a representative base data set for their respective units. In this thesis, we focus on the geo-referencing step of the population in the construction of this data set, where we define the location of the individuals so that the allocation obtained is representative in relation to the population of the region. To do this, we consider the assignment of households to dwellings with specific coordinates by solving a maximum weight matching problem where side constraints are included so that the allocation obtained satisfies statistical structures intrinsic to the considered region. The model of this problem represents each feasible assignment of household to dwelling as a binary variable, which results in billions of variables for medium-sized municipalities such as the city of Trier, Germany. Therefore, standard solvers for mixed-integer linear optimization are not able to solve it due to their high time and memory consumption. Hence, we develop two approaches capable of producing high-quality allocations using a reasonable amount of computational resources, one based on specific decomposition algorithms, and the other characterized by the application of an approximation algorithm in the framework of Lagrangian relaxation of the side constraints. We theoretically explore the allocations obtained by both approaches and perform an extensive computational study using synthetic data sets and real-world data sets associated with the city of Trier. The results show that the developed methods are able to obtain near-optimal solutions using significantly less memory and time than the solver Gurobi, which enables them to tackle significantly larger instances, with approximately 100 000 households and dwellings. Furthermore, the allocations obtained for the real-world data sets correspond to a realistic population distribution, which strengthens the practical applicability of our methods. Lucas Moschen doctoralthesis https://ubt.opus.hbz-nrw.de/frontdoor/index/index/docId/2767 Thu, 27 Nov 2025 06:34:53 +0100 https://ubt.opus.hbz-nrw.de/frontdoor/index/index/docId/2723 Nel libro Dèi e Zangrèi il professor Pasquale Casile scandaglia con mirabile precisione scientifica e in tutta profondità gli abissi della memoria linguistica dei Greci di Calabria. Fornisce risposte valide ai quesiti: Chi sono gli Zangrèi? Sono gli ultimi Dionisiaci della storia e gli eredi diretti delle comunità orfico-pitagoriche della Magna Grecia? E perché vengono così chiamati anche i Catari di Sicilia? Pasquale Casile book https://ubt.opus.hbz-nrw.de/frontdoor/index/index/docId/2723 Thu, 13 Nov 2025 15:41:39 +0100 https://ubt.opus.hbz-nrw.de/frontdoor/index/index/docId/2607 Einige Forschungsergebnisse zeigen, dass emotionale Empfindungen kognitive Bereiche beeinflussen oder mit diesen im Zusammenhang stehen. Aufbauend auf den Ergebnissen wurden zwei Studien konzipiert. In Studie 1 wurde der Zusammenhang zwischen den Valenzen der dispositionalen emotionalen Empfindungen und der globalen Selbstbewertung des Gedächtnisses (Metagedächtnis) bei Lehramtsstudierenden (N = 218) untersucht. Die dispositionalen Empfindungen wurden mittels des deutschen Positive and Negativ Affect Schedule (PANAS) (Krohne, Egloff, Kohlmann & Tausch, 1996) und die globale Selbstbewertung des Gedächtnisses mit dem deutschen Squire Subjective Memory Questionnaire (SSMQ) (Wolf, 2017) erfasst. Angenommen wurde, dass die positive Valenz im Gegensatz zu der negativen Valenz im positiven Zusammenhang mit der höheren Gedächtniseinschätzung stehen. Die Ergebnisse bestätigen die Hypothesen. In Studie 2 wurde die aktuelle Valenz mittels des Open Affective Standardized Image Set (OASIS) (Kurdi, Lozano & Banaji, 2017) induziert, um Veränderungen des Metagedächtnisses und der tatsächlichen Gedächtnisleistung bei Lehramtsstudierenden (N = 44) zu untersuchen. Angenommen wurde, dass die positive Valenz positiv, die negative Valenz negativ und die neutrale Valenz nicht auf das Metagedächtnis und die Gedächtnisleistung wirkt. Weitere Zusammenhänge zwischen dem Metagedächtnis und der Gedächtnisleistung sowie der induzierten Valenz und der Gedächtnisleistung wurden angenommen. Die Messinstrumente aus Studie 1 blieben dieselben. Die Gedächtnisleistung wurde mittels eines sinnarmen Silbentests nach Ebbinghaus (1885) operationalisiert. Die Ergebnisse bestätigen die Hypothesen nicht. Die Emotionsinduktion hatte keinen Erfolg. Die Ergebnisse können damit nicht auf eine veränderte Valenz bezogen werden. Wie in Studie 1 zeigte sich ein Zusammenhang zwischen den dispositionalen Empfindungen und dem Metagedächtnis. Weitere explorative Ergebnisse, vor allem im Bezug auf das Geschlecht, wurden dargestellt. Die Ergebnisse sind bedeutsam für die Professionalisierung von Lehramtsstudierenden. Lena Franziska Pont doctoralthesis https://ubt.opus.hbz-nrw.de/frontdoor/index/index/docId/2607 Tue, 11 Nov 2025 07:47:22 +0100 https://ubt.opus.hbz-nrw.de/frontdoor/index/index/docId/2673 The dissertation is devoted to the construction and justification of three-point difference schemes of high order of accuracy for solving the Sturm-Liouville problem. A new algorithmic realization of the exact three-point difference scheme on a non-uniform grid has been developed. We show that to compute the coefficients of the exact scheme in an arbitrary grid node, it is necessary to solve two auxiliary Cauchy problems for the system of three linear ordinary differential equations of the first order. The coefficient stability of the exact three-point difference scheme is proved. If the Cauchy problems are solved numerically using any one-step method, we obtain the truncated three-point difference scheme. The accuracy estimate of three-point difference schemes was obtained and the algorithm for finding their solution was developed. We also developed a new algorithmic realization of the exact three-point difference scheme for the Sturm-Liouville problem with singularities at the ends of the interval. As in the case of the classical Sturm-Liouville problem, to find the coefficients of the exact three-point difference scheme, it is necessary to solve two auxiliary Cauchy problems for each grid node. The coefficient stability of the exact three-point difference scheme is proved. Since the Cauchy problems for the first and last grid nodes are singular, the Taylor series method has been developed to solve them. The accuracy estimate of truncated three-point difference schemes was obtained. To solve the difference scheme, the Newton's iterative method is used. Numerical experiments are presented which confirm the efficiency of the proposed approach. Nadiya Khomenko doctoralthesis https://ubt.opus.hbz-nrw.de/frontdoor/index/index/docId/2673 Tue, 11 Nov 2025 07:06:29 +0100 https://ubt.opus.hbz-nrw.de/frontdoor/index/index/docId/2606 Diese Studie untersucht die aktuelle Situation auf dem Wohnungsmarkt und die Wohnungspolitik in Rheinland-Pfalz. Sie zeigt, dass in den Städten hohe Mieten und Immobilienpreise, geringe Wohnflächen und eine starke Mietbelastung insbesondere einkommensschwacher Haushalte dominieren. Etwas anders gelagert stellt sich die Lange in den ländlichen Regionen dar: Zwar spielt Eigentum hier eine größere Rolle und der Wohnungsmarkt ist insgesamt entspannter, jedoch schränkt der kleine Mietwohnungsmarkt die Möglichkeiten für Haushalte mit geringem Einkommen erheblich ein. Zudem breiten sich Preissteigerungen zunehmend aus den Städten in umliegende ländliche Räume aus, insbesondere im Umland von Mainz, entlang des Rheins und im Umfeld von Luxemburg. Die in Rheinland-Pfalz angewandten wohnungspolitischen Instrumente – von Mietspiegel und Mietpreisbremse bis zur sozialen Wohnraumförderung – haben nur einen dämpfenden Effekt auf die Wohnungsmarktentwicklung, beheben aber nicht die strukturellen Ursachen der Wohnungsfrage. Insbesondere der Rückgriff auf private Investor:innen und zeitlich befristete Sozialbindungen erweisen sich als grundlegende Konstruktionsfehler. Für eine zukunftsfähige soziale Wohnungspolitik müssen Strukturen gefördert werden, die jenseits des Marktmechanismus agieren. Nur so kann eine verlässliche soziale Wohnraumversorgung umgesetzt werden. Kristin Brosch; Felix Krause; Nils Ludwig; Michael Mießner workingpaper https://ubt.opus.hbz-nrw.de/frontdoor/index/index/docId/2606 Wed, 15 Oct 2025 11:25:57 +0200 https://ubt.opus.hbz-nrw.de/frontdoor/index/index/docId/2590 Biodiversity is threatened by a wide range of anthropogenic activities. Monitoring offers critical insights into how and why biodiversity is changing, helping to identify effective measures for maintaining biodiversity and its ecosystem services. However, conventional biodiversity monitoring methods are labor-intensive, and standardized long-term monitoring series are scarce. DNA-based approaches like metabarcoding environmental DNA (eDNA) promise rapid, cost-efficient, and highly resolved community data. At the same time, scientists are looking for alternative data sources that can compensate for the lack of long-term monitoring data to study past biodiversity changes. This work explores the potential of the German Environmental Specimen Bank (ESB), a pollution monitoring archive, which appears particularly promising for retrospective biodiversity monitoring. Biota samples from different ecosystems across the country are collected and archived at an exceptional level of standardization. Sampling species act as natural eDNA samplers, accumulating genetic traces from surrounding organisms. The cryogenic storage at the ESB preserves any eDNA in the samples in its original state. In this thesis, Chapter I serves as an introductory chapter, outlining the general chances and challenges of metabarcoding for assessing biodiversity. Chapter II focuses on primer design and testing the utility of ESB sampling species like mussels and macroalgae for characterizing the surrounding community. Both chapters form the basis for Chapters III to V, which report the use of ESB time series to uncover sample-associated communities and the changes they undergo. Chapter III illustrates the value of these time series by revealing the invasion trajectory of an alien barnacle into German coastal waters and linking the process to climate change. Chapter IV forms the core of this thesis by presenting an expanded measurement of biodiversity change in ESB time series across different taxonomic groups and ecosystem types. Here, a gradual compositional change (turnover) is reported from bacterial, fungal, microeukaryotic, and metazoan communities tending to either spatial homogenization or differentiation. Observed trends are tested for significance using a dynamic model of community ecology based on the equilibrium theory of island biogeography. The model reveals significantly accelerated turnover rates across all taxonomic groups and ecosystems investigated, suggesting a common, anthropogenically induced driver of biodiversity change. Since these analyses most likely include DNA derived from dead as well as from living organisms, Chapter V aims to separate both groups by metabarcoding both DNA and less stable ribosomal RNA from mussel samples. Contrary to the hypothesis, RNA is detectable from both living endobionts and dietary taxa. However, it outcompetes DNA in detecting microeukaryotic biodiversity. In summary, this thesis demonstrates the outstanding potential of archived ESB samples for retrospective biodiversity monitoring, a resource that offers many further untapped opportunities for future biodiversity research at multiple scales. Isabelle Junk doctoralthesis https://ubt.opus.hbz-nrw.de/frontdoor/index/index/docId/2590 Tue, 23 Sep 2025 13:22:42 +0200