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- Institut für Wirtschafts- und Verwaltungsinformatik (14)
- Mathematisches Institut (14)
Die vorliegende Dissertation unternimmt eine grundlegende Neubewertung des Werkes von Stefan Andres (1906–1970), der nach seiner Zeit als Bestsellerautor der Nachkriegsjahre weitgehend aus dem literarischen Kanon verschwunden ist. Entgegen der herkömmlichen Rezeption, die Andres oft auf seinen als nicht mehr zeitgemäß erachteten christlichen Humanismus oder auf seinen Ruf als Heimatdichter reduziert, weist die Arbeit nach, dass sein Œuvre eine hohe Modernität besitzt und komplexe Identitätsdiskurse sowie Alteritätserfahrungen verhandelt, die für die globalisierte Gesellschaft des 21. Jahrhunderts von hoher Relevanz sind.
Methodisches Rückgrat der Untersuchung ist die kontrapunktische Lektüre im Sinne Edward Saids, die durch das poststrukturalistisch geprägte Instrumentarium Homi K. Bhabhas erweitert wird. Im Zentrum stehen dabei Bhabhas Konzepte der Hybridität, des Dritten Raumes, der Mimikry und der Ambivalenz. Diese Theorien, die ursprünglich im Kontext kolonialer Machtverhältnisse entstanden sind, werden in dieser Arbeit erfolgreich auf die literarische Darstellung innereuropäischer und geschlechtsspezifischer Machtasymmetrien transferiert.
Anhand der Romane „Die unsichtbare Mauer“ (1934) und „Die Reise nach Portiuncula“ (1954) wird aufgezeigt, wie Andres binäre Oppositionen – etwa zwischen urbanem Zentrum und ruraler Peripherie – sowohl inszeniert als auch subversiv unterlaufen werden. In der Analyse des Romans „Die unsichtbaren Mauer“ wird der Bau der Dhrontalsperre als eine koloniale Situation gedeutet, in der technokratisches Wissen zur epistemischen Gewalt gegenüber einer marginalisierten Landbevölkerung wird. Beim Roman „Die Reise nach Portiuncula“
wird die metaphorische Afrikanisierung des italienischen Schauplatzes demaskiert, die dazu dient, die Protagonistin Assunta als exotisierte „Andere“ zu konstruieren und patriarchale Herrschaftsansprüche zu legitimieren. Die Arbeit belegt, dass die weiblichen Figuren bei Andres sich starren Stereotypen entziehen und sich durch Formen der „schlauen Höflichkeit“ oder gewaltsamen Widerstand zu handlungsstarken Subjekten entwickeln.
Abschließend zeigt die Dissertation, dass das Re-Reading von Stefan Andres durch die Brille der Postcolonial Studies nicht nur dessen Werk neu erschließt, sondern auch die Leistungsfähigkeit kulturtheoretischer Analysewerkzeuge für die Germanistik unter Beweis stellt. Damit leistet die Arbeit einen wesentlichen Beitrag zur aktuellen Debatte um die Erweiterung des literarischen Kanons und die Dekonstruktion eurozentrischer Wahrnehmungsmuster.
In order to support both the provision of clean drinking water and the preservation of biodiversity in aquatic ecosystems, a comprehensive scientific understanding of the identity, concentration, and behavior of anthropogenic pollutants in the aquatic environment is essential. Organic micropollutants constitute a large group of anthropogenic pollutants and originate from all areas of daily human life: pharmaceuticals are part of the daily routine for many people, pesticides are crucial for food production, and organic chemicals are used in the industrial production of paper, plastics, paints, and many other products. These micropollutants enter the water cycle, either in their parent form or as transformation products, where they can lead to potentially harmful effects. In addition to target methods, non-target approaches have been established as powerful tools for comprehensively investigating these compounds in the water cycle. Beyond the analytical challenges of instrumentally detecting these compounds, the prioritization and evaluation of the large datasets generated by non-target pose both chemical and data science challenges, forming the overarching theme of this work.
The work comprises three studies demonstrating the development and application of non-target screening (NTS) methodologies. In an NTS using high-performance liquid chromatography (HPLC) coupled with high-resolution mass spectrometry (QTOF-MS/MS), 112 samples from the river Nidda and seven of its tributaries were analyzed. On average, approximately 2700 signals, or features, were detected per sample. To filter these extensive data and prioritize unknown compounds, a method was first developed to reliably assign adducts, isotopologues, source fragments and other ionization products to a common component based on retention time and peak shape. In the next step, the prioritization of unknown compounds was achieved by highlighting features that were detected specifically at individual sites under investigation, but which were not typically considered to originate from municipal wastewater. This was accomplished by comparing the data from the Nidda river system with NTS data from municipal wastewater treatment plant effluents. Only the highlighted, Nidda-specific features were considered further. As a result, an average data prioritization of 7% across all samples was achieved, leading to the identification of nine compounds. Among these were the industrial compound Nylostab S-EED™, which had not been previously observed in the environment and three algal toxins, whose occurrence resulted from the algal bloom of a nearby water body.
In the second study, investigations focused on permanently cationic compounds in suspended particulate matter samples from the rivers Rhine and Saar. The data prioritization was based on the specific physicochemical properties of this substance group. Following extraction, a two-step procedure was applied, relying on interactions with strong ion exchangers and chromatography using deuterated solvents. This resulted in 5% of the detected NTS signals being labeled as potentially cationic compounds. Based on this, 22 compounds were identified, four of which were previously unknown. Trend analyses covering the period from 2005/2006 to 2018, along with an assessment of the ecotoxicological risks based on semi-quantitatively determined concentrations, suggest that identified compounds such as Basic Yellow 28 and Fluorescent Brightener 363 may have a high ecotoxicological relevance.
The third study focused on the analysis of samples from disconnected, inter-regional river systems. In collaboration with the local environmental authorities, a three-year study was conducted, analyzing 524 samples from 79 sites along rivers across Saxony. For this purpose, a method was developed that allowed for the characterization of sites based on five categories, considering both known and unknown compounds to assess their chemical contamination. The results were classified by calculating the modified z-scores within each category. The method was validated based on the results of target analysis in the same samples. As a result of the study, 13 sites were classified as anomalous due to high z-scores, as elevated levels of pharmaceuticals, industrial chemicals but also unclassified unknown compounds were detected. At two potentially industrially contaminated sites, the Münzbach and Dorfbach Oberschindmaas, nine compounds were identified and their concentrations were estimated using a 1-point calibration. For the compound hexa(methoxymethyl)melamine, a concentration in the range of 300 µg/L was determined, suggesting a considerable risk for the environment (risk quotient: 5.6).
Microplastics (MP) (1 μm to 5 mm) enter riverine environments in various ways. Point sources (e. g. industrial plants) can be differentiated from diffuse sources (e. g. erosion). Once MP has entered river systems, it underlies hydrodynamic processes and is finally transported towards the oceans. Due to fragmentation, MP particles decrease in size during transport. MP particles are highly heterogeneous considering density and shape, which makes spatially and temporally high resolved sampling difficult and thus hampers the quantification of annual loads in rivers. Within this thesis, we conducted a spatially and temporally high resolved monitoring in the River Rhine with the aim to quantify an annual MP load at our study site, Koblenz.
With a literature review we exposed that most studies present their results by means of particle number instead of particle mass. Also, many studies did not consider spatial nor temporal aspects within their sampling design. For the first time, we presented a compilation of global annual load values within river systems, partly using innovative methodological approaches to convert MP items to MP mass. Hereby, a correlation between catchment area and annual MP load could be detected. Global loads showed a large range (< 1 kg/y – 1533 t/y).
To estimate the annual MP load of the River Rhine at the study site Koblenz, we performed a temporally high resolved sampling using sedimentation boxes (SB, time-integrated samples over months) and a continuous flow centrifuge (CFC, discrete sampling). Via thermal degradation procedures, polymer concentration in mg/g was estimated for PP, PE, PS and PVC. Hereby, annual loads of 400 t (SB) and 60 t (CFC) were calculated. Deviation of both methods was more pronounced for polymers with lower density (PP and PE), whereas PVC loads were comparable. This led to further laboratory experiments, which showed that particle retention efficiency of the SB was varying with the particle’s properties. Thus, the SB sample might not be representative for the river’s conditions. Furthermore, the CFC had difficulties in retaining polymers with lower density (losses up to > 50 % were noticed). Nevertheless, the calculated MP loads do fit well into our compilation of global MP load values. An extensive quantification of retention efficiencies for several polymer types and particle sizes (SB) or an additional sampling step for the clearwater of the CFC for low-dense MP particles could lead to more robust MP concentration values in the future.
Depth-distributed sampling campaigns with a filter cascade and filter nets revealed strong density-dependant vertical gradients within the water column. These gradients were even apparent within the smallest particle size classes and thus were larger than a theoretical determination based on the Rouse number would have suggested. Both, filter cascade and filter net showed a positive correlation between river discharge and MP concentration. This correlation allows for a first speculation on MP sources within the River Rhine: The main source of MP seems, in congruence with suspended sediments, to be a diffuse entry which rises with rising water level. In contrast, a constant entry from a point source would lead to lower concentrations during flood events due to dilution.
Within this work we could point out that extensive research is needed considering the understanding of different sampling devices and their sampling efficiencies. First approaches for an improvement of these limitations have been shown. Still, a combination of sampling techniques is necessary to cover the portfolio of potential issues regarding MP research. For a more precise quantification of annual MP loads, standardisation of procedures on all working steps is urgently needed.
This study investigated the acquisition of skills by future maths teachers in Rhineland-Palatinate during
their final internship phase before entering the so-called `Vorbereitungsdienst´, a kind of in-depth in-
ternship/ practical training.
In order to record the students' learning progress, a pre/post-test approach was chosen in which the
participants each analysed five short teaching sequences in an online questionnaire and then answered
questions on mathematical argumentation. So the test reflected a central content of the internship,
the observation and reflection of maths lessons.
All video sequences were focussed on aspects of mathematical argumentation in the classroom. Ma-
thematical reasoning not only describes one of the general competences laid down in the educational
standards and curricula for the subject of mathematics, but also goes beyond the other general com-
petences in terms of its fundamental importance for mathematics lessons.
In the test group, a total of 54 trainees was surveyed at the beginning and at the end of their in-depth
internship in four internship periods in 2022 and 2023. The control group consisted of 28 student tea-
chers of mathematics, who were also surveyed twice at 3-week intervals without completing a school
placement in the meantime.
The collected data sets, which essentially consist of free text responses, were analysed using the qua-
litative content analysis method. In addition, the interpretative uncertainty that arises here was mini-
mised through backward testing. In this way, the quantity and quality of the video analysis as well as
the knowledge and understanding of mathematical argumentation could be determined and com-
pared for each respondent in both tests.
As a result, the study confirms previous findings regarding the perception of teaching by experts and
novices and also the fundamental increase in knowledge through practical phases. In addition the
study shows that both quantitative and qualitative response behaviour improved after the practical
training and the test participants were able to identify aspects of argumentation in the lesson excerpts
and justify their importance for good mathematics teaching. This was more successful in teaching si-
tuations that are not very dynamic than in teaching situations that are very dynamic, such as those
arising from conversational situations. In addition, a deeper understanding of the competence `ma-
thematical argumentation´ could be demonstrated after the internship and it could be seen that the
didactic knowledge and the ability to analyse videos correlate more strongly with each other in the
post-test than in the pre-test.
The effects described were only evident in the test group, but not in the control group without the
work placement.
Positron Emission Tomography (PET) is becoming more and more important in clinical routine
applications. One of the major limitations is the sensitivity to patient motion especially in the thorax
to periodic respiratory movement. Another open point of discussion is the method how to define the
tumor volume, especially when the precise knowledge of the tumor borders is important as in
radiation treatment planning. Therefore, in this work these two topics to improve quantification in
PET imaging have been addressed. First a new motion correction algorithm was implemented using
image deblurring including movement information of a 4D Computed Tomography (CT). This method,
which has the advantage of not increasing the PET acquisition time as other motion correction
techniques, was applied to phantom and patient data and showed promising result in improvement of lesion quantification. In phantom studies an improvement of up to 49% in lesion volume and in
patient studies of up to 33.3% could be demonstrated.
In the second part of this work, a new segmentation method based on textural parameters was
implemented and validated as well in phantom and patient data. In the latter a validation with
histopathological data was performed showing a very good performance of the new algorithms,
especially in larger lesions. Best result could be shown in phantom data and patient data for the
segmentation algorithm based in the local entropy.
In summary, two algorithms were implemented and validated which can improve quantification of
PET imaging furthermore
In recent decades, there has been a growing awareness in our society of the impor-
tance of medicines that are personalized to the needs of patients. This dissertation
contributes to the research on personalized dosage forms with controlled drug release.
The basis of our investigations is the simulation of the expected diffusion properties
of these personalized dosage forms using computer-aided statistical methods and the
subsequent adaptation of suitable models to experimentally obtained data. This
novel approach makes it possible to verify the parameters determined from exper-
imental data, such as the diffusion coefficient. A key finding is that, for instance,
the homogeneity of the sample, the precision of the measurement data collection
and the consideration of the measurement environment have a greater influence on
the validity of the diffusion coefficient than the choice of the diffusion model. The
experimental part of this thesis comprises the development and characterization of
drug-loaded polymer resins, the implant fabrication, and the pharmaceutical and
physical investigation of the polymer-drug implants. The formulation of polymer
resins and their suitability for 3D printing (3DP), as well as their use in pharmaceu-
tical applications, are extensively addressed. The release properties and, in partic-
ular, the polymer network’s mesh size influence on the active ingredient’s diffusion
rate in aqueous solution are studied. In addition, the production of polymer sam-
ples by means of UV photopolymerization in a molding process developed for this
purpose, as well as by using stereolithographic 3DP, are examined comparatively.
The polymerization process and the polymer properties resulting from the different
production methods are presented. The major findings from these studies include
the successful development of a polymer resin formulation whose release and swelling
properties are comprehensively demonstrated using a model drug. Furthermore, the
optimization of this resin for the use of the active pharmaceutical ingredient (API)
testosterone was achieved. A comparison of the two developed resin formulations
clearly shows the limitations and the possibilities of transferability of both systems.
In addition, the results concerning the release of API from the polymer, as well as
the diffusion of the solvent into the polymer and the resulting increase in the volume,
provide insight into the changed interfacial diffusion resistance in 3D printed poly-
mers compared to molded polymers. This work thus contributes to the development
of personalized drug forms and paves the way for the production of release-controlled
polymer resin implants for future follow-up work.
The rapid evolution of wireless communication technologies, particularly the introduction
of Fifth-Generation (5G) networks and the anticipated transition to Sixth-Generation (6G)
systems, ushers in a new era of connectivity, enabling transformative applications across
industrial automation, the Internet of Everything (IoE), and the Industrial Internet of Things
(IIoT). However, the exponential growth in the number of connected devices, stringent reliability
requirements, and increasing security challenges pose significant hurdles for current network
architectures. This dissertation addresses these challenges by proposing innovative frameworks
and mechanisms that enhance reliability, optimize resource utilization, and strengthen security
and trust management in next-generation mobile networks.
The first contribution of this dissertation focuses on reliability enhancements in 5G networks.
While existing mechanisms, such as Dual Connectivity (DC) and Network Function (NF)
redundancy, provide partial solutions, they do not fully resolve application-layer reliability
and dynamic server failover. To bridge this gap, this work introduces the Make-Before-Break-
Reliability (MBBR) and enhanced Make-Before-Break-Reliability (eMBBR) mechanisms. These
frameworks proactively establish redundant communication paths, ensuring seamless failovers
with minimal latency and service disruption. By extending reliability to the application layer
and integrating adaptive path selection and dynamic failover capabilities, these mechanisms
offer robust solutions for latency-sensitive and mission-critical applications.
The second major contribution addresses bandwidth optimization for industrial networks.
The black channel paradigm, widely adopted for industrial safety applications, relies heavily on
cyclic keep-alive messages to detect connection loss, leading to significant signaling overhead.
This dissertation proposes a novel solution leveraging 5G Channel State Information (CSI)
to replace cyclic messaging with real-time connection quality monitoring. By exposing CSI
metrics, such as Signal-to-Noise Ratio (SNR) and Channel Quality Indicator (CQI), to the
application layer, the proposed mechanism reduces bandwidth consumption while maintaining
the safety and reliability requirements of industrial networks.
Addressing the growing complexity of security requirements in IIoT, the third contribution
introduces the AF-based Security Framework (AERO) framework. This framework empowers
application providers to dynamically apply cryptographic mechanisms to the user plane,
overcoming the limitations of legacy protocols and eliminating the need for redundant security
layers. By ensuring backward compatibility and enabling both static and dynamic configuration
of user plane encryption, AERO enhances security while minimizing computational overhead
and reducing transmission delays.
The fourth and final contribution redefines trust management in mobile networks through
the SecUre deleGAtion of tRust (SUGAR) framework. Traditional trust models, which rely
on identity chips for each connected device, are becoming increasingly impractical in the
IoE era, where billions of devices require connectivity. The SUGAR framework introduces a
delegation-based trust model, allowing Parent Devices (PaDs) to delegate trust to multiple
Child Devices (ChDs) securely. This approach eliminates the need for individual identity chips,
significantly reducing costs and enhancing scalability. Integration with System-on-a-Chip
(SoC)-based identity enclaves further strengthens the security of trust credentials.
The findings of this dissertation offer substantial contributions to both academia and
industry. The proposed frameworks effectively address critical gaps in current 5G standards
and provide valuable contributions for developing the 6G framework. By enhancing reliability,
optimizing bandwidth, and redefining security and trust management, this dissertation provides
a comprehensive foundation for the design and deployment of next-generation mobile networks.
Furthermore, the solutions presented are adaptable to a wide range of applications, including
industrial automation, autonomous systems, and smart city infrastructures.
In conclusion, this dissertation represents a significant step toward realizing the full
potential of next-generation mobile networks. By addressing key challenges in reliability,
resource optimization, security, and trust management, the proposed frameworks pave the way
for scalable, secure, and efficient mobile ecosystems that are essential for the dynamic and
interconnected world of the future.
Improving patient care is an ongoing process, evolving from early evidence-based practices to modern AI-driven approaches. This thesis explores three key research directions aimed at improving clinical decisionmaking through AI. Adverse events, defined as negative and harmful outcomes that occur during medical care, present major challenges for hospitals. Most data-driven research using electronic health records relies on data from tertiary referral hospitals, but their patient population differs from those in hospitals of medium level of care. The first major contribution of this thesis is a data-driven Trigger Tool for predicting adverse events trained on data from a hospital of medium level of care. This tool uses a concise set of laboratory values measured within the first 24 hours of hospitalization. In addition to models using numerical features, we devised models using dichotomized features that indicate whether a laboratory value falls below or above a reference threshold. Our findings show that models using numerical features achieve high accuracy in predicting acute kidney injury and the COVID-19 associated adverse events in-hospital mortality and transfer to the ICU. Models using dichotomous features performonly slightly worse but offer better interpretability.
The second major contribution is the online-updateable AI model OptAB for selecting optimal antibiotics in sepsis patients. OptAB aims to minimize the sepsis-related organ failure score (SOFA-Score) while accounting for nephrotoxic and hepatotoxic side effects. OptAB relies on a hybrid neural network differential equation algorithm tailored to the special properties of patient data, including irregular measurements, missing values, and time-dependent confounding. Time-dependent confounding describes a dependence between time-varying covariates and treatment decisionsmade by physicians, often leading to biased treatment effect estimates. OptAB generates disease course forecasts for (combinations of ) the antibiotics vancomycin, ceftriaxone, and piperacillin/tazobactam and learns realistic treatment effects on the SOFA-Score and side effect indicative laboratory values. Results indicate that OptAB’s recommendations achieve faster efficacy than the administered antibiotics while reducing side effects.
The third major contribution is DoseAI, an online-updateable AI model that extends OptAB to optimize dosing regimens. DoseAI mitigates time-dependent confounding in dosage selection by minimizing the absolute spearman correlation between predicted and future treatment dosages. It forecasts disease progression under alternative dosing regimens and proposes optimal chemotherapy and radiotherapy dosing regimens for synthetic cancer patients. These regimens effectively reduce the tumor volume while adhering to varying maximum allowed weight loss constraints, used as a measure of toxicity.
Mathematiklehrkräfte sind bisher unzureichend auf die Digitalisierung des Mathematikunterrichts vorbereitet. Daher ist es notwendig bereits im Studium passende Lernangebote zur Entwicklung professioneller Kompetenzen für den Einsatz digitaler Mathematikwerkzeuge zu schaffen. Im Rahmen der vorliegenden Arbeit wird eine fachdidaktische Lehrveranstaltung für angehende Mathematiklehrkräfte der Sekundarstufen
konzipiert, um deren professionellen Kompetenzen mit Blick auf den Einsatz digitaler Mathematikwerkzeuge im Kontext der Leitidee Strukturen und funktionaler Zusammenhang zu fördern. Neben Werkzeugkompetenzen zur Nutzung der digitalen Mathematikwerkzeuge sollen die Kompetenzen zur Planung und Gestaltung von Mathematikunterricht entwickelt werden. Für das Themenfeld funktionale Zusammenhänge sind die beiden digitalen Mathematikwerkzeuge GeoGebra und Tabellenkalkulationsprogramm besonders relevant. Deren Potentiale für das funktionale Denken werden insbesondere in Bezug auf Darstellungsformen und Repräsentationswechsel sowie Lernschwierigkeiten thematisiert. Ergänzend zu den genannten Kompetenzen werden zudem Überzeugungen zum Einsatz digitaler Mathematikwerkzeuge in den Blick genommen. Diese haben einen erheblichen Einfluss darauf, ob die erworbenen Kompetenzen im eigenen Unterricht eingesetzt werden oder nicht.
Zur Ermittlung des Ist-Zustands bei Kompetenzen und Überzeugungen der angehenden
Mathematiklehrkräfte vor dem Besuch der Lehrveranstaltung wurden zwei Erhebungsinstrumente entwickelt und eingesetzt. Neben einem Fragebogen zur Selbsteinschätzung erfolgte die Datenerhebung mittels eines neu entwickelten Kompetenztests
im Sinne eines Leistungstests. Es zeigte sich, dass die professionellen Kompetenzen und Vorerfahrungen bei den Studierenden äußerst heterogen sind.
Um Rückschlüsse auf die Wirksamkeit der Lehrveranstaltung ziehen zu können, wurden die beiden Erhebungsinstrumente im Pre-Post-Design eingesetzt. Die Ergebnisse nach Besuch der Lehrveranstaltung lassen auf positive Effekte schließen. Gleichzeitig wird deutlich, dass eine einzelne Lehrveranstaltungen im Studium nicht ausreicht. Zudem besteht Bedarf an weiterer Forschung in diesem Bereich, insbesondere was die Untersuchung langfristiger Effekte und die Zusammenhänge zwischen den verschiedenen Kompetenzfacetten und Überzeugungen betrifft.
In view of the requirement that students (e.g. in Rhineland-Palatinate) from grade 7 onwards
have to work independently with dynamic geometry software (e.g. GeoGebra) and a
spreadsheet program, teachers have a special role in the integration of digital mathematics
toolsin mathematics lessons. For example this can be implemented, with regard to the guiding
idea L4 (Functional connection), since the use of digital mathematics tools is recommended to
promote functional thinking. Within the qualitive offensive for pre-service-teacher training,
which has been established by the Ministry of Education, the project MoSAiK provided a
Digital Research Workshop Multiple Representations in Mathematics Education using the
topic of elementary functions on secondary school level. On the one hand this workshop
examined tool skills of students in relation to the two softwares GeoGebra and spreadsheets
that apply for secondary schools, high schools and vocational schools. On the other hand
(technology-related) beliefs of the students were researched according to the function
concept.
For that reason a specific didactic workshop, which included on the one hand the fostering of
operating skills for the tools GeoGebra and spreadsheet and on the other hand the
subsequent planning and teaching of lessons had been conceived. Before and after attending
the workshop the operating and selection skills in both tools have been measured in a sample
of 55 students using a self-developed competency test. In addition, the sub-areas TK, TPK and
TCK of the TPACK-framework, self-efficacy beliefs and technology-related beliefs regarding
the advantages and disadvantages of using digital mathematics tools were collected using a
student questionnaire. The workshop intervention achieved a significant effect on the
development of the students' operating skills for both tools – GeoGebra and spreadsheet. The
results of a qualitative content analysis with quantitative elements show that in particular the
visualizing of functions and the checking of results were viewed as advantages of the digital
tools when teaching functional thinking. The most frequently cited disadvantage was a danger
to manual calculation methods. With regard to the time required, on the one hand, savings
were expected when using digital tools, but on the other hand, there were fears of high
expenditure if pupils do not have the necessary tool skills.
Mit der Demographischen Dividende (DD) wird ein wirtschaftlicher Vorteil beschrieben, der aus einer Verschiebung der Altersstruktur einer Gesellschaft hin zu einem höheren Anteil erwerbsfähiger Bevölkerung resultiert. Ursprünglich am Beispiel der so genannten ‚Tigerstaaten‘ Südostasiens entwickelt, gilt die DD als ein Modell für wirtschaftliches Wachstum durch Fertilitätsrückgänge. Die vorliegende Dissertation befasst sich diskursanalytisch mit der Verwendung des Konzepts in Entwicklungszusammenarbeit, Politikberatung und Bevölkerungsforschung sowie dessen Übertragung auf den Globalen Süden als ein leitendes Paradigma in der internationalen Entwicklungszusammenarbeit. Hierzu wurden teilstrukturierte Interviews mit Expertinnen und Experten geführt.
Die Debatte um die DD ist von uneinheitlichen Definitionen darüber geprägt, was die DD genau ist. Eine technisch-mathematische Perspektive sieht die DD als reine Folge der Altersstrukturverschiebung, während eine behavioristische Sicht zusätzlich die Auswirkungen individueller Faktoren wie Bildung, Emanzipation und wirtschaftlichen Handelns mit einbezieht. Ein Wachstumseffekt durch Altersstrukturverschiebungen wird im Globalen Südens voraussichtlich weniger stark ausfallen als in Südostasien. Gründe hierfür sind langsamere Fertilitätsrückgänge, geringere Arbeitsmarktanteile und unterschiedliche sozioökonomische Rahmenbedingungen. Hinzu kommt, dass heute die Prinzipien von sexueller und reproduktiver Gesundheit und Rechte (SRGR) zu respektieren sind, die während des südostasiatischen Wirtschaftswunders nicht etabliert waren. Dieses Leitbild wurde im Jahr 1994 auf der Konferenz für Bevölkerung und Entwicklung in Kairo hegemonial. Faktoren wie Bildung, soziale Sicherungssysteme, politische Stabilität und globale Abhängigkeiten sind jedoch ebenso entscheidend für den sozialen und wirtschaftlichen Fortschritt.
Entwicklungspolitische Programme propagieren vielfach Familienplanung als Schlüssel zur DD, doch stoßen diese Programme auch auf Kritik. Denn die Institutionen, welche den Diskurs um die DD dominieren, haben zum Teil eine problematische historische Verbindung zu eugenischen oder rassistischen Programmen, was der Glaubwürdigkeit ihrer Positionen schaden kann. Zudem werden die Programme in großen Teilen von eben diesen privaten Stiftungen und Initiativen mit fragwürdiger Historie finanziert, so dass die Macht über die Ausgestaltung derartiger Programme von staatlichen Akteurinnen und Akteuren hin zu privaten Akteuren verschoben wird. Die Interviews und die weiterhin verwendete Literatur zeigen auf, dass langfristige Investitionen in Bildung, Gesundheitsversorgung und soziale Sicherungssysteme größere und nachhaltigere wirtschaftliche Fortschritte bewirken als rein demographische Ansätze. Und trotz ihrer Einschränkungen bleibt die DD ein nützliches Konzept, sofern sie in einen breiteren Kontext eingebettet wird. Die Herausforderung besteht darin das Konzept so anzuwenden, dass es nicht nur in einem technokratischen Verständnis hegemonial wird, sondern dass die Verbindungen zwischen der Verschiebung von Bevölkerungsanteilen, Bildung, Stärkung des Gesundheitswesens und Wirtschafts- wie Arbeitsmarktpolitik verstanden werden.
The integration of the different stakeholder needs and environmental constraints is the key goal of requirements engineering. This demands collaborations between involved parties, to reach “understandability of the system”, what is particularly challenging for collaborations over different organisations. High quality requirements engineering is the key factor to address these challenges. Requirements are input to all development steps and carry the knowledge to exchange—requirements engineering is an overall life-cycle spanning and in its essence a knowledge management task.
The main goal of the T-Reqs framework presented in this thesis is to enable semantic interoperability and to sustain the knowledge by conceptualization of the requirements engineering process applied to European space projects. T-Reqs’ objective is to formally capture the information carried by the requirements to provide top-shelf inputs for the consecutive system and discipline-specific development tasks, in particular within model-based systems engineering. Emphasis is placed on the nature of relationships that exist among requirements and requirement documents. The T-Reqs formalism addresses the structuring of requirements as well as their potential reuse, e.g., in product line development or even between different projects. This implies an overall System Requirements Specification that is distributed in many specifications documents and involves requirements of different levels of abstractions from abstract goals to implementation details. This thesis especially focuses the specification and validation of such requirements documents.
The T-Reqs traceability model provides a means to trace not only individual requirements,
but also consider relations among views such as documents, taking into account the role
they play for stakeholders, especially in reuse. It is shown, how formalization of dependencies, such as for tailoring of standards, enables automated quality checks to facilitate reviews and enhance completeness and consistency of the overall specification.
Towards the structuring of requirements itself, different syntactic template systems aim to
increase the quality of requirement documentation. Within this thesis a comparative evaluation of these notations is conducted, supporting that claim and differentiating the strength and weaknesses of different approaches. Special emphasis is not only laid on documentation quality, but also the usefulness of these semi-formal notations for integration with model-based development methods. This is achieved through the representation of concepts, which can be managed in special contextualised glossaries.
Overall it can be shown that conceptualization of requirements engineering knowledge can support requirements engineering in different aspects and a holistic approach to integrate different tasks lays the foundation for semantic interoperability spanning organizations and life cycle phases.
The production and use of polymeric materials have been increasing continuously for
years. At the same time, the entry of microplastics (MP) – tiny particles resulting from the
wear and tear of these materials – into our environment is growing as well. By now,
awareness of MP has reached broad sections of the population and also research and
development on this field are similarly becoming increasingly important. However,
insufficient standardization and the lack of suitable analytical methods still make
recording and tracking of MP difficult, so that it remains largely unregulated. Mass-based
analytical methods are particularly advantageous for the establishment of legal
regulations. Apart from thermogravimetric methods, however, there are currently few
alternatives in this field. In this context, the use of nuclear magnetic resonance
spectroscopy (NMR), previously only qualitatively applied to MP, has now also been
examined for its quantitative benefits. This work deals with the current state of
quantitative NMR spectroscopy (qNMR) and tests possibilities for optimization and further
development for this purpose. Initially, the reduction of sample volumes and thus
minimized effort and measurement time of the method will be examined by combining
different polymer types into simultaneously measurable groups, as well as the suitability
of homopolymer calibrations for the detection of copolymers. Existing restrictions during
measurement will be adopted, and thus extractive procedures for sample preparation are
implemented. Finally, the influence of real environmental samples will be assessed, and
measures to reduce interfering factors will be taken in to account. As a result, the method
encompasses at least six polymer types, from PMMA, PS, BR, and PVC to PA and PET, as
well as separate approaches for polymers such as PAN and LDPE. A modular sample
preparation protocol, including extractive fractionation into measurement groups and a
chemical digestion method for matrix reduction, will be established and expanded to
include options for diffusion measurement and application to low-field instruments.
Practical application will be presented using real-world examples, such as freshwater
biofilms, as well as the use for quality control of certified reference materials.
Furthermore, initial insights into future development possibilities, like for the detection of
tire abrasion, will be provided.
The presence of synthetic chemicals in the environment can affect both ecosystems and
human health. In particular, the increasing contamination of the aquatic environment by
complex mixtures of anthropogenic trace substances has become a major global concern.
Once released into the environment, these compounds can undergo diverse
transformation processes to form a wide range of transformation products (TPs), which
are commonly unknown. Transformation inevitably alters the pattern of contamination and
exposure, as new substances are formed with frequently different physicochemical
properties, environmental behavior and toxicity in comparison to their precursor
compounds. For instance, TPs can exhibit significantly greater persistence and mobility in
the aquatic environment, posing a threat to both aquatic ecosystems and drinking water
resources. Therefore, TPs need to be considered in the risk assessment and authorization
process of chemicals. However, due to a combination of predictive, analytical, and
regulatory challenges, TPs currently remain largely unrecognized and unregulated. By
addressing these challenges, this thesis comprehensively characterizes the entry paths,
occurrence, fate, and (eco)toxicological relevance of selected TPs in the aquatic system in
Germany. These TPs have been largely overlooked in environmental studies and aquatic
monitoring programs for decades, despite their precursors being produced and used in
large quantities on a global scale.
The highly persistent and mobile substance trifluoroacetate (TFA) has garnered
significant attention in recent years due to its diverse sources, widespread occurrence in
the aquatic environment, and the lack of economically viable options to remove TFA from
contaminated waters. One of the most frequently discussed diffuse sources is the
formation of TFA in the atmosphere through the oxidation of volatile precursors and its
subsequent scavenging from the atmosphere by wet deposition. Despite the previously
reported occurrence of TFA in precipitation, the lack of recent and comprehensive data
has severely limited the understanding of the significance of wet deposition as a source of
TFA to the (aquatic) environment. Thus, in the present work, a nationwide field monitoring
campaign covering all precipitation events over a one-year sampling period was
conducted at eight sites across Germany. Samples were analyzed for TFA using ion
exchange chromatography (IC) coupled to negative-ion electrospray tandem mass
spectrometry (ESI-MS/MS). Of the analyzed samples, 16% exhibited TFA concentrations
≥ 1 μg/L. The precipitation-weighted average TFA concentration of 0.34 μg/L highlighted
that wet deposition alone is responsible for approximately 0.3 to 0.4 μg/L of TFA in
surface waters in Germany. The annual wet deposition fluxes ranged from 91 to
400 μg/m², with the highest fluxes observed in densely populated regions. The annual wet
deposition of TFA for Germany during the observation period was estimated to be 68 t.
The sampling revealed a pronounced seasonality, with the highest concentrations and wet
deposition fluxes of TFA observed in summer. Pearson correlation analyses indicated that
the transformation of TFA precursors in the troposphere is enhanced in summer due to
elevated concentrations of photochemically generated oxidants, primarily •OH, which
ultimately results in increased atmospheric TFA deposition. Overall, the study provided the
first published data on TFA in precipitation in Germany since 1995/96. The derived data
serves as a benchmark for future studies. In addition, it allows for the establishment of
mass balances and can be used to develop models to predict the loads of TFA entering
the aquatic environment from multiple sources.
The lack of robust historical data on the wet deposition fluxes of TFA also impeded long-
term trend analyses. Specifically, a postulated increase in atmospheric formation and
deposition of TFA due to substantial emission increases of numerous volatile TFA
precursors in recent decades remained unquantified. To address this knowledge gap,
archived plant samples were analyzed to evaluate the long-term temporal trends in the
atmospheric deposition of TFA in Germany. A robust and highly sensitive analytical
method for TFA in plant matrices was developed and validated. The method
encompassed a three-step sequential extraction procedure followed by the analysis of the
diluted sample extracts using IC-ESI-MS/MS. Subsequently, archived leaf samples of
various tree species and sampling sites from the German Environmental Specimen Bank
(observation period: 1989−2020) were analyzed for TFA. Statistical analysis revealed
significant (p < 0.05) positive trends in TFA concentrations in plant leaves, which is likely
the result of both phytoaccumulation and increasing emissions of gaseous TFA precursors
over the observation period. The concentrations increased by factors of up to 12 from
1989 to 2020. The highest concentrations (up to ∼1,000 μg/kg dry weight) were found in
Lombardy poplar leaves. Overall, the study presents the first trend analysis of TFA in biota
and raises awareness of the escalating atmospheric deposition of TFA over the past three
decades.
Sulfamate has previously been identified as a TP of the artificial sweeteners cyclamate
and acesulfame in wastewater and drinking water treatment. The preliminary results
indicated that sulfamate concentrations in wastewater treatment plant (WWTP) effluent
are substantially higher than those of other wastewater-borne contaminants. However,
despite its high global production and usage, no information was available on the sources,
occurrence, and environmental significance of sulfamate in the aquatic system in
Germany. To close this knowledge gap, a quantitative monitoring approach of different
urban water cycle compartments was conducted. Target analysis based on IC-ESI-MS/MS
revealed exceptionally high concentrations of sulfamate in wastewater (up to 1,900 μg/L),
surface water (up to 580 μg/L), and finished drinking water (up to 140 μg/L) in Germany.
Considering the limited data on short-term ecotoxicity, approximately 30% of the
sulfamate concentrations detected in groundwater and surface water samples exceeded
the derived predicted no-effect concentration (PNEC) of sulfamate. Therefore, the
potential impact of sulfamate on the aquatic ecosystem in Germany cannot be excluded.
Municipal WWTP effluent was identified as the primary source of sulfamate for the aquatic
system, as its concentrations correlated positively (r > 0.77) with the municipal wastewater
tracer carbamazepine in samples from different waterbodies. Ozonation and activated
sludge experiments demonstrated that sulfamate can be formed through chemical and
biological degradation of various precursors containing a sulfonamide group.
Nevertheless, the transformation of precursors to sulfamate in WWTPs and receiving
waters was found to be quantitatively insignificant, due to the substantial direct use of
sulfamic acid as a descaling agent in domestic and industrial applications. Laboratory
batch experiments, in conjunction with the findings from the sampling conducted at full-
scale waterworks, demonstrated that the commonly applied drinking water treatment
techniques, including ozonation and activated carbon filtration, are largely ineffective in
removing sulfamate. Bank filtration was identified as the only option to efficiently eliminate
sulfamate from contaminated raw water resources (removal: 62% to 99%). Overall, the
study presents the first comprehensive analysis of sulfamate in the urban water cycle and
suggests that there may be other high production volume inorganic chemicals that are
currently overlooked in environmental studies and monitoring programs.
Despite pantoprazole (PPZ) being one of the most widely prescribed human
pharmaceuticals globally, consistently low concentrations of this proton-pump inhibitor in
environmental water samples have been documented. This can be attributed to the
extensive metabolism of PPZ within the human body, with only minor amounts of the
parent compound being excreted. Since environmental monitoring and risk assessment
for regulatory purposes focus on the parent substances of pharmaceuticals, it was
assumed that the current environmental exposure associated with the use of PPZ is
considerably underestimated. In the presented thesis, 4′-O-demethyl-PPZ sulfide (M1)
was identified as the most relevant PPZ metabolite for environmental analysis. This was
achieved by applying reversed-phase high-performance liquid chromatography (RP-
HPLC) coupled to high-resolution mass spectrometry (HRMS) to urine samples of a PPZ
user, as well as to municipal wastewater. M1, which had not been investigated in previous
monitoring studies, was found to be ubiquitous in WWTP influent and effluent (max.:
3 μg/L, detention frequency: 100%) as well as in surface water (max.: 1.2 μg/L; detection
frequency: 97%) in Germany. Its average surface water concentration was approximately
30 times higher than that of the parent compound PPZ. Moreover, quantitative structure-
toxicity relationship (QSTR) modeling indicated a lower preliminary freshwater PNEC for
M1 (4.8 μg/L) compared to PPZ (28 μg/L). The analysis of archived suspended particulate
matter (SPM) samples from the Rhine at Koblenz revealed that the concentrations of M1
increased significantly from 2005 to 2015 and were positively correlated with the
prescription volume of PPZ. Conventional biological wastewater treatment was found to
be insufficient to remove M1 (average removal: 22%). Laboratory-scale experiments and
the analysis of samples taken after different treatment steps of an advanced full-scale
WWTP demonstrated that post-treatment with activated carbon as well as ozonation can
significantly improve the removal of M1 and PPZ during wastewater treatment, thereby
reducing their release to the aquatic environment. During ozonation, a rapid oxidation of
M1 was observed, accompanied by the formation of several ozonation products, which
were proposed for the first time. The identity of the main ozonation TPs of M1 was
confirmed through the synthesis of reference compounds. Their detection in samples
collected after the ozonation step of a full-scale WWTP demonstrated the transferability of
the laboratory-scale ozonation experiments. M1 was found to be sufficiently removed from
contaminated source waters (max. raw water concentration: 0.25 μg/L) by bank filtration
under different redox conditions (removal ≥ 80 %) and by other commonly applied
purification processes in drinking water production. In summary, this study revealed that
the environmental exposure and risk associated with the use of PPZ have been previously
underestimated, which likely extends to other human pharmaceuticals. Therefore, these
findings call for more sophisticated approaches to environmental monitoring and risk
assessment of pharmaceuticals that take TPs into account.
This thesis provides an in-depth understanding of the entry paths, occurrence, fate, and
environmental significance of selected TPs in the aquatic system in Germany. It
significantly advances our understanding of the introduction of TFA into the water cycle,
by characterizing the source of wet deposition and elucidating long-term temporal trends
of atmospherically deposited TFA. Additionally, the thesis gives comprehensive insights
into the formation, behavior, removability, and potential (eco)toxicological risks of
sulfamate, PPZ and its TPs. The thesis addresses key challenges in assessing and
integrating TPs into chemical management and presents solutions to overcome these
challenges. Finally, it highlights the urgent need for increased focus on TPs in research,
aquatic monitoring, and regulation to safeguard the environment and human health.
Age-structure changes are an intrinsic feature of the demographic transition from high mortality and
fertility to low mortality and fertility. Initially, the demographic transition increases the share of the
working-age population, creating opportunities for economic boosts through demographic dividends.
Particularly some Asian countries have benefited greatly from such demographic dividends in the past.
Overtime, however, the demographic transition leads to population ageing, which brings various
implications for economies and societies worldwide. In Asia, many countries are ageing rapidly, while
others continue to maintain a relatively young age structure. These differences may also be related to
migration. Migration is also often discussed as a possible policy response to counteract population
ageing. This thesis identifies global patterns in changes in the share of working-age population and
examines associated demographic factors. With a specific focus on Asian countries, it assesses the
impact of migration on population ageing in the past and its potential impact in the future.
All analyses in this thesis are based on data from the United Nations’ World Population Prospects 2022.
First, past, present and projected age-structure changes are analyzed in the context of demographic
dividends, covering 148 countries worldwide. Cluster analyses are conducted to identify patterns of
age-structure changes between 1950 and 2100, while linear regression models are used to detect
associations between these changes and relevant demographic factors. Second, the impact of
migration on past age-structure changes is assessed for the period 1990-2020 in 51 Asian countries
using decomposition analysis. An existing decomposition approach is extended to incorporate the
concept of prospective age, which accounts for differences in life expectancy when assessing
population ageing. Third, the potential impact of migration on population ageing between 2022 and
2050 is analyzed in eleven Asian countries by adopting the United Nations’ replacement migration
concept. In this analysis, both chronological and prospective indicators of population ageing are
applied.
The results underline the heterogeneity of global age-structure changes in the course of the
demographic transition. This underscores the need to take into account a country’s specific
demographic development when assessing its potential for a demographic dividend. The experience
of some Asian countries, where rapid fertility declines in the past have been followed by sharp
increases in the share of the working-age population, is only one of several global patterns. Differences
in age-structure changes are associated with differences in fertility, but also with migration and
population momentum – two factors that have so far received relatively little attention in the
discussion of demographic dividends. Focusing on Asian countries, this thesis reveals that differences
in population ageing across countries are at least partly driven by migration. However, the volume of
migration potentially required to offset population ageing over the next decades seems unrealistically
high in most countries. The results emphasize that migration can play a role in age-structure changes,
but population ageing can barely be halted by immigration alone. Thus, comprehensive policies seem
to be a key factor in ensuring further development in ageing countries in Asia and beyond.
In der Dissertation Freiheit und Werte bei Jean-Paul Sartre wird das Verhältnis zwischen
Freiheit und Werten in der Philosophie von Jean-Paul Sartre analysiert. Es wird untersucht, auf
welche Weise die existenzielle Freiheit des Menschen mit seinen moralischen und
außermoralischen Werten nach Sartre zusammenhängt. Ziel der Untersuchung ist es, einen
Beitrag zum Verständnis von Sartres Wertlehre sowie seiner Ethik der Authentizität zu leisten.
Grundlage für die Untersuchung bilden neben Sartres philosophischen Werken, seine
literaturtheoretischen sowie politisch-gesellschaftlichen Schriften. Ausgehend von einer
Analyse der existenziellen Freiheit bei Sartre wird der vielschichtige Zusammenhang zwischen
Freiheit und Werten bei Sartre analysiert und in den Gesamtkontext seiner Philosophie gestellt.
Die Dissertation zeigt, dass sich in Sartres Werk sowohl eine subjektivistische als auch eine
objektivistische Wertlehre ausmachen lässt. Während Sartre in vielen Passagen seines Werkes
die subjektivistische Position vertritt, dass alle moralischen und außermoralischen Werte auf
das bewertende Subjekt zurückgehen, präsentiert er an anderen Stellen seines Werkes den
moralischen Wert der Freiheit sowie den außermoralischen Wert des An-sich-für-sich.
Abgesehen von jenem Spannungsverhältnis macht die Untersuchung deutlich, dass der
moralische Wert der Freiheit für Sartre innerhalb seiner gesamten Philosophie von großer
Bedeutung ist. Eine Verwirklichung jenes Wertes ist nach Sartre nicht nur zentraler Bestandteil
einer engagierten Literatur, sondern auch für eine gerechte Gesellschaft wesentlich.
Eisenbahnunternehmen setzen Condition Monitoring Systeme (CMS) zur Überwachung ihrer Anlagen und Komponenten ein. CMS sind im Risikomanagement der Branche relevant, aber ihr Einsatz leidet unter einem Präventionsparadoxon: Sie werden oft erst nach Schäden oder Richtlinien eingeführt. CMS können auch den Instandhaltungsaufwand reduzieren. Bei den streckenseitigen WTMS tragen Infrastrukturbetreiber die Kosten, während Verkehrs-unternehmen den Nutzen durch effizientere Instandhaltung sehen. Um fundierte Geschäftsmodelle zu entwickeln, muss deshalb der Nutzen von CMS quantifiziert werden. Die Informationsqualität, einschließlich der Sensoren und der Symptomaussagekraft, beeinflusst diesen Nutzen. Diese Verbindung von Anwendungswert und Nutzen ist bisher unzureichend erforscht. Aufgrund dessen ist das Forschungsziel folgendermaßen gesetzt worden: Entwicklung eines systemdynamischen Modells und eines Verfahrens zur Erfassung des Informationswertes von Condition Monitoring Systems, anhand des Fallbeispiels der Radsatzlagerüberwachung im Eisenbahnverkehr.“
Das Forschungsziel dieser Arbeit umfasst als Erkenntnisziel das Verständnis der Zusammenhänge und Wechselwirkungen im CMS und dabei den Nutzen des Einsatzes der Systeme zu bewerten. Das Gestaltungsziel beinhaltet die Untersuchung der Eignung des systemdynamischen Verfahrens. Zur Erreichung dieser Ziele sollen folgende Forschungsfragen beantwortet werden:
1. Welche Ziele verfolgen die Eisenbahnorganisationen in Bezug auf den Betrieb ihrer Radsatzlager und inwiefern können die Informationen aus den Messdaten der heutzutage eingesetzten Radsatzlagerüberwachungssysteme zur Zielerreichung beitragen?
2. Lassen sich mit der systemdynamischen Vorgehensweise, die für die Bewertung von CMS relevanten Wechselwirkungen im Eisenbahnsystem abbilden?
3. Lässt sich anhand der systemdynamischen Vorgehensweise untersuchen, welche Informationen für die Erhöhung des Nutzens der Radsatzlagerüberwachungssysteme relevant sind?
Die Ergebnisse der Arbeit erwirken die Erkenntnis, dass die Methodik dazu geeignet ist, die relevanten Zusammenhänge und Wechselwirkungen darzustellen und mithilfe der Simulationsergebnisse relevante Instandhaltungsstrategien und der Nutzen von RDMT zu bewerten. Damit sind die Ergebnisse sowohl für die Forschung als auch für Entscheidungsträger in der Eisenbahnbranche relevant.
Water is the basis of all life, a biotope for a variety of organisms and an important component of the
natural balance. For this reason, it is essential to protect water from contamination by anthropogenic
organic micropollutants (MPs) and to develop various innovative strategies for the treatment and reuse
of wastewater. Conventionally biologically treated municipal wastewater contains many organic MPs
that pose a potential threat to aquatic ecosystems and drinking water resources. To date, the focus has
been on physicochemical processes such as activated carbon treatment or ozonation to improve the
removal of MPs in wastewater treatment plants (WWTPs), while knowledge of biological removal
processes and ways to optimize the biological removal of organic MPs is comparatively limited.
Especially in arid and semi-arid regions, treated wastewater is also an important resource for wastewater
reuse for irrigation or drinking water treatment. In consequence of increasing droughts due to climate
change, the reuse of treated wastewater is also increasingly being discussed in Germany. Often the water
is reused after targeted groundwater recharge, while concepts for optimizing the removal of MPs during
soil passages are still scare. In order to assess the potential and limitations of biological wastewater
treatment as well as targeted groundwater recharge for the removal of organic MPs, a better knowledge
of the biological biotransformation processes and the environmental conditions influencing them is
required. Microbial communities and their enzyme pools play a key role in these processes. However,
the influence of environmental conditions on the composition and functional characteristics of microbial
communities, and how this in turn affects the biotransformation potential of MPs with different
structural characteristics, has been little studied. In addition, knowledge about MP-biotransforming
bacteria is often derived from enrichment or even pure culture studies, which are not directly transferable
to the environment.
Against this background, this dissertation focuses on the systematic investigation of the
biotransformation of MPs in contact with activated sludge (simulation of biotransformation processes
in biological treatment stages of WWTPs) and filter materials (simulation of processes in groundwater
recharge systems) under defined laboratory conditions. The aim is to elucidate relationships between
the composition and functional characteristics of microbial communities, microbiologically determined
biotransformation processes and their optimal process conditions, as well as the chemical structure and
primary enzymatically catalyzed biotransformation reactions of MPs.
The first part of the work focuses on the composition of microbial communities and the
biotransformation of MPs depending on defined process parameters in five differently operated
wastewater reactors, divided into two reactor cascades at pilot scale and one full-scale WWTP. The first
cascade consisted of three reactors, the first of which served as a reference reactor with conventional
activated sludge (CAS) treatment. The following reactors operate under anoxic to anaerobic and strictly
anaerobic conditions, respectively. The other cascade consists of two reactors, the first anaerobic and the second aerobic, followed by a simplified vessel to prevent nitrate output, as half of the effluent was
recirculated to the first anaerobic reactor. All five reactors and the WWTP were analyzed for the
biotransformation of 33 MPs and the composition of the microbial community by LC-MS/MS and 16S
rRNA gene sequencing, respectively. The results showed a slight but significant improvement in the
overall biotransformation of MPs in the reactor cascades (about 20%) compared to the WWTP. In
particular, the biotransformation of compounds that are not or only slightly degradable (< 30%) in
conventional wastewater treatment, such as diatrizoate, venlafaxine and diclofenac, was significantly
improved (about 70%). Twelve of the 33 MPs showed an increase in biotransformation of at least 30%
compared to the reference reactor and the WWTP. In detail, the reactor cascade consisting of the
anaerobic pre-treatment showed three times more MPs than the reactor cascade with the anaerobic post-
treatment. Although the environmental conditions (nutrient availability and redox conditions) differed
considerably between the reactors, molecular analysis of the microbial community revealed a core
community of 143 genera, with 54% of the taxa belonging to the phylum Proteobacteria, with the beta
subdivision as the most dominant class. On the other hand, a specialized community consisting of 90
genera was identified that contributed most to the differences between the reactor communities. These
genera were shown to reflect the prevailing nutrient, redox and operating conditions of each treatment.
It was also found that the relative abundances of several genera of the specialized community correlated
with the biotransformation of certain MPs as well as with process parameters (especially redox
conditions). These genera may not necessarily be directly involved in the biotransformation of MPs, but
could be promising biological indicators for the establishment and control of operating conditions
favorable to the biotransformation of certain MPs. For the two reactor cascades analyzed, it was
concluded that the redox conditions as well as the carbon supply were essential factors for the
composition of the specialized community and the biotransformation of the MPs. In addition, the 16S
rRNA gene amplicon sequencing proved to be a complementary tool to confirm process conditions by
correlation. In conclusion, the efficiency of MP biotransformation in conventional WWTPs depends on
key parameters such as redox conditions, biodiversity or the presence of several genera of specialized
microbial communities identified as indicator organisms.
Against the background of previous knowledge that biofilms from moving bed biofilm reactors
(MBBRs), which have been used so far in a few WWTPs, are more efficient in biotransforming certain
MPs, the second study used laboratory batch experiments to investigate the extent to which the
biotransformation potential of carrier-attached biofilms and suspended sludge from hybrid MBBRs
differ between three WWTPs, and whether these differences were also reflected in the composition of
the bacterial communities. The 31 MPs investigated were grouped according to their biotransformation
rates and examined for relationships between the biotransformation behavior and the known primary
biotransformation reactions are discernible. In general, the study confirmed the potential of hybrid
MBBRs for improved biotransformation of a variety of MPs. This could be attributed to an increased
biotransformation potential of the carrier-attached biofilms, especially for oxidatively degradable substances such as trimethoprim, diclofenac and mecoprop. Correlation analyses showed statistically
significant relationships between the occurrence of certain bacterial genera (e.g. Acidibacter, Nitrospira
or Rhizomicrobium) and the biotransformation rates of certain MPs. Thus, some of the identified genera
were also discussed as suitable indicators for the biotransformation potential of suspended sludge or
carrier-attached biofilm.
In the third part of the work, the biotransformation of up to 78 MPs was investigated under different
redox and substrate conditions in a defined column system at laboratory scale as well as ex situ under
uniform incubation conditions by incubating the column filter material in batch experiments. MPs were
categorized based on their biotransformation behavior and how well these categories matched primary
transformation reactions known from the literature or predicted using the Eawag pathway prediction
system for modelling microbial biotransformation pathways. The column system investigated consisted
of two large columns filled with technical sand, an intermediate aeration and four smaller columns, all
connected in series. In the first column, characterized by a carbon-rich environment with high biomass
and strong oxygen depletion, 23 MPs were efficiently removed (>80% removal), while 19 substances
were better or exclusively removed under carbon-limited oligotrophic conditions in the columns after
re-aeration. While the MPs removed predominantly in the first column were mostly attributed to
biotransformation by comparatively ubiquitous and fast transformation reactions such as the oxidation
of alcohols or amide hydrolysis, the biotransformation of MPs removed more efficiently under the oxic
and oligotrophic conditions in the rear columns was characterized by slower transformation reactions
such as N-dealkylation of primary and secondary amines or the hydroxylation of aromatic rings. In
addition, several specific reactions described in the literature, such as the cleavage of C-Cl and C-O
bonds, could only be identified under oligotrophic conditions. The results suggest that conditions of
limited carbon availability may favor the development of alternative metabolic biotransformation
pathways. Furthermore, the observed association between system-specific MP removal and the expected
primary biotransformation reactions from the literature and prediction systems could serve as a basis for
accurately identifying the relevant enzymes in future studies, using metagenomic or metatranscriptomic
data.
Based on these considerations, molecular biological investigations were carried out in the fourth part of
this work by generating sequence-based data complementary to the biotransformation rate constants
during the batch experiments carried out in the third study. A first aim was to identify a statistical relation
between the microbial composition, the process conditions and the nutrient availability as well as the
biotransformation potential of 42 MPs depending on the biomass in the columns of the system.
Furthermore, the metabolic activities of the microbial communities of the first two columns of the
system were analyzed and the identified active enzymes were assigned to known metabolic pathways
and the activities were compared. In addition, the extent to which the biotransformation potential of the
columns was also reflected in the activity of enzymes that have been proven to belong to biotransformation pathways of MPs was investigated. To this end, modern sequencing methods were
used to generate data on the composition of the microbial community (16S rRNA gene sequencing) and
its actual activity in the form of expressed genes (metatranscriptome sequencing). The biotransformation
rates from the batch experiments of the third study were used by normalizing them with the gene copy
numbers (kbio), which were representative of the biomass. For half of the MPs, the highest normalized
kbio values were identified in the rear columns with increased carbon-limiting conditions. Furthermore,
most of the MPs investigated, such as sulfathiazole, sulfamethoxazole or rufinamide, showed an
improved biotransformation potential in these columns. The higher biotransformation potential under
carbon-limiting conditions was also confirmed by metatranscriptomic analysis, where an increased
metabolic capability and a higher functional activity to degrade MPs were observed in the carbon-
limiting column compared to the first nutrient-rich column. Taxonomic analysis revealed a decreasing
trend in biodiversity with a simultaneous increase in carbon-limiting conditions. Furthermore, the
microbial community differed depending on the nutrient and process conditions of the column materials
analyzed. However, within the carbon-limiting columns, the microbial community was similar and were
dominated by the genus Pseudomonas. By relating the biotransformation of MPs to the relative
abundance of taxa in the carbon-limiting columns, the genera of the phylum Acidobacteria and the
classes Alpha- and Gammaproteobacteria showed particularly high associations. In addition, four genera
showed a statistically positive correlation with the two structurally similar MPs sulfamethoxazole and
sulfathiazole.
Overall, no general improvement in biotransformation could be found for all MPs under the conditions
considered, with system- and condition-specific changes observed for individual compounds. However,
the studies indicated favorable environmental conditions for groups of MPs that showed increased
biotransformation linked with high abundant taxa, especially under carbon-limiting conditions and in
carrier-attached biofilms.
Within the scope of this work, new test methods were developed to determine the characteristic product properties of ladle well filler sands. Background is that up to now, there are no approved test methods for these product properties such as pourability, sintering behavior and infiltration behavior.
To substantiate this deficiency in testing methods, the general state-of-the-art testing methods of cohesionless bulk materials is presented and a variety of publications on ladle well filler sands are reviewed for their applied testing methodology.
The development of new test methods for the characterization of ladle well filler sands was based on test methods that were in part already standardized, such as the permeability measurement (infiltration) according to DIN 18130-1 from the field of geotechnics, the determination of the flow time with flow cups for coating materials (flowability) according to DIN EN ISO 2431:2011 and the monotonic heating method (MMH) according to ASTM E2584-20 for determining the thermal conductivity.
Since these test methods were not designed for examining free-flowing, non-cohesive bulk materials and therefore not for examining ladle well filler sand, it was necessary to adapt the parameters of the standardized test methods for use with well filler.
The parameters of the test methods mentioned (DIN 18130-1; DIN EN ISO 2431 and ASTM E2584-20) were checked for applicability and transferability to ladle well filler sand and new suitable parameters were added. The reproducibility of the results of the test methods was checked by a series of tests and the decisive influencing factors of ladle well filler sand on the results were determined.
The relevance of the results of the newly developed test methods was verified based on results from the European research project ILORA ("Improvement of Ladle Opening Rates", funded by the "Research Fund for Coal and Steel" RFCS, 2013-2016) and numerous publications with results from other research projects.
From the results of the newly developed test methods, key figures for the pourability, sintering behavior and infiltration behavior of ladle well filler sands were derived. The combination of these key figures was converted into a holistic analysis of ladle well filler sands, finally leading to an evaluation grid for well fillers. It is exactly that grid respectively network, that now allows for the first time to make qualified and reliable statements about the suitability for use of ladle well filler sands prior to industry application, which significantly facilitates the new development of such well fillers.
Microplastics (MP), i.e., plastic particles < 5 mm, are perceived as a threatening envi-
ronmental and human health issue. Growing public interest in this class of contaminants
requires standardized and harmonized methods for their quantification. While an abun-
dance of analytical methods (both particle-based and mass-based) for the detection of
microplastics is available, existing studies on the quantity of MP in the environment lack
comparability. Therefore, the aim of this work was to establish a fast, reliable screen-
ing method for the quantification of the most common synthetic polymers in complex
environmental samples.
This was accomplished by a two-step pressurized liquid extraction (PLE) followed by
analysis via pyrolysis coupled to gas chromatography and mass spectrometry (Py–GC–
MS). In the first extraction step, a large part of the organic matrix was removed with
methanol at 100 ∘C and 100 bar, followed by a second step with tetrahydrofuran at
185 ∘C and 100 bar to extract the polymers that were subsequently adsorbed to silica
gel and measured with Py–GC–MS. With the developed method, limits of quantification
in an environmentally relevant concentration range of 7–8 μg g−1 for the most common
thermoplastic polymers polyethylene (PE), polypropylene (PP), and polystyrene (PS)
were achieved.
In order to improve the robustness of the method, poly(styrene-d5) (PSd5) was initially
applied as internal standard. However, further analyses revealed a deuterium–hydrogen
exchange during Py–GC–MS measurement, which was catalyzed by the inorganic ma-
trix. This effect was thereupon systematically investigated and poly(4-fluorostyrene) was
established as a new, stable internal standard.
While the developed method enabled the quantification of PE, PP, and PS, several other
polymers had to be excluded. In particular, the quantification of poly(ethylene tereph-
thalate) (PET) proved challenging via Py–GC–MS. A variety of catalytic effects by the
inorganic matrix was revealed and systematically investigated, e.g., changes in pyrolysis
product distribution. Several different sample preparation approaches failed to resolve
these issues. PLE led to a depolymerization of PET which was also catalyzed by the
inorganic sample matrix.
After further optimization and reduction of false positives, the developed method has
the potential to be included in future standardized procedures for MP quantification. It
provides a fast, robust analysis of MP in complex samples, while also considering widely overlooked matrix effects. Potential quantification approaches for other polymers that are
not included in the developed method (e.g., tire wear particles, paint particles) are also
discussed in this thesis.
Invasive crayfish are a serious threat and ecosystem engineers that compete with native species for shelter and food resources, show combative interactions against native species, and negatively affect species diversity. In this work, I used two North American invasive crayfish species that have successfully spread across Europe spinycheek crayfish (Faxonius limosus) and signal crayfish (Pacifastacus leniusculus) as models to assess their potential Impacts on native benthic fish, stone loach (Barbatula barbatula) and bullhead (Cottus gobio), which are among the most common benthic fish in Europe. I have investigated the competition for shelter and agonistic interactions between these invasive crayfish species and the native benthic fish species under laboratory conditions have employed a multi-object tracking algorithm to monitor and visualize the fish's and crayfish's activity inside the experimental tank. Spinycheek and signal crayfish successfully displaced both benthic fish species from their shelter. Both crayfish species attected the behaviour of stone loach, reducing its activity and increasing its hiding outside the shelter. Although bullheads did not reduce shelter use, they displayed similar behavioural changes, if less intense, In addition, I demonstrated remarkable aggressive interactions by both crayfish species against stone loaches and bullheads. Further investigations were performed to assess how variations in crayfish density influence the structure of invertebrate communities. I conducted comparative analyses of community composition across nine stream sites with varying densities of signal crayfish in Wied Stream, Germany. These findings revealed a correlation between crayfish density and diversity and evenness of invertebrates, suggesting that signal crayfish pose a substantial threat to Invertebrate biodiversity
In conclusion, this thesis reveals that these invasive crayfish species not only compete with native biota for essential resources but also fundamentally alter the ecological dynamics of freshwater habitats. This thesis emphasises the urgent need to manage and mitigate the potential consequences of crayfish invasion and to preserve native aquatic ecosystems.
In sowohl den Kulturwissenschaften als auch den Kognitionswissenschaften haben sich neuere
Theorien etabliert, welche verstärkt die Verkörperung und Materialität unseres Denkens, Fühlens und
Handelns betonen. Diese Dissertation untersucht aus der Perspektive der philosophischen
Anthropologie, wie die ‚material culture studies‘ sowie die ‚embodied cognition‘-Forschungen
zusammengedacht werden können. Im Fokus liegt hier der Phänomenbereich der Musik: Denn nicht
nur spielen bei dieser eine Vielzahl von Gegenständen der materiellen Kultur eine zentrale Rolle
(Instrumente, Tonträger, etc.), sondern auch der Körper des hörenden oder musizierenden Subjekts.
Die philosophische Reflexion erfolgte vor allem aus der Perspektive des Enaktivismus, einer
spezifischen Strömung der ‚embodied cognition‘, ergänzt durch Konzepte und Ansätze aus den
Traditionen der Phänomenologie und des Pragmatismus. Diese wurden nicht nur herangezogen, um
zusammen mit dem enaktivistischen Denken auf der Sachebene die verkörperte Natur der Musik
darzustellen, sondern auch um die methodische Problemstellung zu behandeln: Der
phänomenologische Gedanke des Doppelaspekts von Leib und Körper (Fuchs) und die pragmatistische
Anthropologie der Artikulation (Jung) dienten eben dazu, das Zusammendenken von Kognitions- und
Kulturwissenschaften in Bezug auf Musik zu ermöglichen.
So ließen sich verschiedene Detailfragen zu den beiden größeren Themenkomplexen der
Wahrnehmung von und des Umgangs mit Musik(-kultur) beantworten, inklusive solche bezüglich der
Rolle des Affektiven und des Sozialen sowie nach der möglichen Ausdehnung von Kognition und Leib.
Zusätzlich ergab sich so auch eine exemplarische Demonstration der methodologischen Gedanken, da
diese Fragestellungen anhand der genannten Konzepte untersucht wurden und so deren Fruchtbarkeit
für das Verbinden von natur- und kulturwissenschaftlichen Forschungen dargelegt werden konnte.
Schülerinnen und Schülern eine wirkungsvolle Begegnung mit Literatur zu ermöglichen, stellt hohe Anforderungen an die Unterrichtsvorbereitung: Material muss ausgewählt und gestaltet, Lernaufgaben müssen vorbereitet und eingesetzt und Unterrichtsgespräche müssen antizipiert und moderiert werden. Gerade von Referendarinnen und Referendaren können die damit verbundenen Anforderungen als sehr herausfordernd – auch als überfordernd – empfunden werden.
Mit dem Ziel, den auszubildenden Lehrerinnen und Lehrern ein erstes handhabbares Instrumentarium zur Planung und Gestaltung des Literaturunterrichts an die Hand zu geben und ihnen dadurch zu frühen ‚Gelingenserfahrungen‘ zu verhelfen, wurde am Studienseminar für das Lehramt an Gymnasien in Koblenz ein Ausbildungsmodell entwickelt. Der Erörterung, wie die Implikationen dieses Modells auch auf den Literaturunterricht übertragen werden können, widmet sich die Dissertation.
Auf die verschiedenen Faktoren zur Steuerung des Unterrichts – die Phasierung der Stunde, die Formulierung von Lernaufgaben, die Darbietung des Materials und die Moderation der Unterrichtsgespräche – blickend, werden unterschiedliche Handlungsoptionen vorgestellt und didaktisch ausdifferenziert. Stichprobenuntersuchungen aus zwei Unterrichtsstunden – zu Rilkes Gedicht ‚Natur ist glücklich‘ (Klasse 9) und zu Bettina Wegners Lied ‚Gebote‘ (Klasse 12) – veranschaulichen und konkretisieren die Positionen.
Aus der Verbindung der didaktischen Überlegungen mit den empirischen Stichprobenuntersuchungen entsteht der Entwurf eines neu nuancierten Ausbildungsmodells für den hermeneutisch-diskursiven Literaturunterricht.
For most humanoid robots, falls are the predominant limiting factor affecting their applications and autonomy to move in irregular environmental conditions. A similar susceptibility to falls can also be observed in humans during various daily activities due to balance control deficits or neuromusculoskeletal disorders. Despite the remarkable adaptability of the human locomotor system, as well as recent developments in robotics, balance loss and falls persist. To gain new insights into the complex interactions between bipedal locomotion and balance loss, we linked humanoid robots and humans into humanoid systems and focused on the accurate monitoring of the locomotor segment’s kinematics. This is an essential component for detecting and assessing balance disturbances, thereby improving the robustness during bipedal locomotion. Therefore, this thesis focused on the development of an inertial measurement cluster for direct kinematic measurements of, i.e. omitting numerical differentiation, a mathematical process that greatly amplifies single noise. However, despite the aim to increase the resilience of the bipedal locomotion and thereby reduce the fall risk in humanoid systems, the methods applied in this thesis had to differ in addressing the detection and assessment of balance disturbances. Therefore, the thesis comprises three sets of studies concerning the fields of humanoid robotics, humans, and sensor uncertainty assessment. In the first theoretical study, we introduced the mathematical concept of the inertial measurement cluster with special emphasis on its impact on providing sensory feedback on detected situational loss of balance during bipedal locomotion in humanoid robots. This was achieved through a kinematics-driven framework based on robust inverse dynamics evaluation and the reduction of numerical differentiation in critical terms by directly measuring the angular acceleration vector. Subsequently, we proposed a sensor fusion algorithm to estimate both the magnitude and application line of externally applied forces on robots in theory. In the second set of studies about humans, we addressed the remote detection and assessment of trip and slip events. Therefore, the sensitivity of the proposed wearable sensor-framework system (inertial measurement cluster combined with an evaluation framework) to automatically detect balance disturbances was examined. We were able to automatically assess the balance recovery performance of individuals and resolved the well-known adaptation phenomena to repeated trip-like perturbations. Subsequently, we expanded the functional scope of the wearable sensor-framework system and provided evidence of its high accuracy in detecting and classifying balance disturbances during simulated activities of daily life. In the third set of studies, we established a multi-method framework to provide an experimental angular acceleration reference to objectively quantify the measurement uncertainty of the proposed inertial measurement cluster. Moreover, we confirmed the reference can serve as a measurement standard. Finally, based on the measurement standard, we proposed a concept for an adjustment routine to compensate for the deterministic errors of the inertial measurement cluster and confirmed a measurement uncertainty reduction. In conclusion, we established a sensor suitable for humans and humanoid robots, omitting numerical differentiation, and confirmed its significantly reduced measurement uncertainty. The proposed framework approaches based on the inertial measurement cluster were the key factors for the accurate detection of balance disturbances in humanoid robots as well as humans, highlighted by comparisons to conventional methods based on numerical differentiation. Consequently, the proposed sensor and frameworks have the potential to provide new insights into the causes of balance disturbances or factors that lead to insufficient reactive actions to prevent falls in humanoid robots and humans.
Feuerfestmaterialien nehmen in industriellen Prozessen, die hohe Temperaturen erfordern, eine maßgebliche Rolle ein. Eine vollständige Charakterisierung ihrer Eigenschaften ist erforderlich, um potentielle Defizite zu identifizieren und adäquate Struktur-Eigenschafts-Korrelationen prognostizieren zu können. Die vorliegende Arbeit evaluiert anhand von drei exemplarischen Anwendungsbeispielen die Eignung der Röntgen-Computertomographie (engl.: X-Ray Computertomography, XRT) als Analysemethode zur Untersuchung feuerfester Materialien. Der Schwerpunkt liegt hierbei auf Strategien zur Untersuchung des Gefüges hinsichtlich seiner Strukturen, Defekte sowie Porosität bzw. Porenverteilung und -morpho-logie und darüber hinaus auch auf der Analyse von Rissen. Die XRT ermöglicht die hochauflösende, zerstörungsfreie, dreidimensionale (3D) und reproduzierbare Untersuchung innerer und äußerer Strukturen des Körpers. Die im Rahmen dieser Arbeit durchgeführten Studien verdeutlichen, welches Potential sich insbesondere bei der Kombination der XRT mit konventionellen Methoden ergibt.
Analyse und Bewertung der Resilienz von Unternehmen und Geschäftsprozessen aus Ressourcensicht
(2025)
Companies can be affected by events that adversely impact their business operations. These events can originate from corporate environments or within companies themselves. The effects of these events may be quite diverse and can threaten the survival of companies in the worst case. To deal with events that can adversely impact business operations of companies, the concept of resilience can be used. The concept of resilience relates to the ability of companies to handle adverse circumstances. It encompasses different aspects from measuring to restoring and strengthening the resilience of companies. This dissertation deals with the concept of resilience within the corporate context. It considers the concept of resilience from a company and business process perspective and provides different research contributions for this contexts. From a company perspective, a concept and a model are presented that serve as the basis to analyse the resilience of companies. The concept shows essential elements that are important for considering the resilience of companies. The model outlines the range that can be used to analyse the resilience of companies. Furthermore, a corporate maturity model is introduced to assess the resilience of companies. It encompasses different attributes and resilience levels to determine and improve the resilience of compannies. From a business process perspective, a lifecycle and metrics for business process resilience are presented. The lifecycle shows different phases relating to resilience considerations of business processes. The metrics are used to measure the resilience of business processes.
Bacterial communication via chemical messengers, also called quorum sensing (QS), plays a major role in bioluminescence, pathogenicity and biofilm formation of bacteria. For humans, biofilm formation is undesired in areas as shipping, healthcare and water treatment because it hinders technical processes and there may be health risks for humans. To prevent the formation of unwanted biofilms (so-called biofouling), for example in shipping industry, different antifouling agents such as copper oxide are used. In water treatment, disinfectants such as sodium hypochlorite are used to reduce the occurrence of pathogens as well as build-up biofilms to ensure microbiologically safe water. Common antifouling agents in the marine industry are usually based on their toxicity and their release into the environment. These agents could be dangerous for the ecosystem and sustainable alternatives are needed. For this purpose, nanomaterials were developed which, according to the researcher’s hypothesis, influence the QS-system of Gram-negative bacteria and thus prevent biofouling. The hypothesis claims that the nanomaterials mimic the defence strategy of marine organisms with vanadium-bromoperoxidases (V-BrPO) and produce via a catalytic process reactive halogen species such as hypobromous acid. Reactive halogen species also play a major role in disinfection with e.g. sodium hypochlorite. The disinfecting effect is based on oxidation processes with biological material of the microorganism. But, also an influence on the QS system of Gram-negative bacteria was described, which has not yet been investigated in detail. In this thesis, the hypothesized influence of the developed nanomaterials and that of the disinfectant free active chlorine (FAC) on the QS-system of Gram-negative bacteria are investigated. The aim of this thesis was to expand the knowledge about QS molecules (QSM) with regard to degradation processes induced by reactive halogen species and how to analyse QSMs and their transformation products (TP). This allows better assessment at the level of bacterial communication of processes such as antifouling and disinfection. In order to study the communication of Gram-negative bacteria, liquid chromatography – tandem mass spectrometry (LC-ESI-MS/MS) was used to develop a sensitive and selective method for the quantification of QSMs N-acyl-homoserine lactones (AHL), which provide information about QS. Due to the high diversity of AHLs and their low concentrations in the environment a solid-phase extraction was developed and optimized for 34 AHLs. The validated method can measure AHLs in the low ng/L concentration range in several matrices such as surface water, treated wastewater or bacterial supernatants. AHLs were detected in river water (in total 5 AHLs) and treated wastewater (in total 3 AHLs), which shows that the developed method is satisfactory for the detection of environmental concentrations. Furthermore, an unanticipated variety of AHLs was detected in the bacterial supernatants of Pseudomonas aeruginosa (in total 8 AHLs), Phaeobacter gallaeciensis (in total 6 AHLs), and Methylobacterium mesophilicum (in total 15 AHLs). To our knowledge these AHLs have not been described in the literature for these bacterial cultures so far. Quantification of AHLs was performed using a standard addition method and concentrations up to 7.3±1.0 μg/L (3-Oxo-C12-AHL in the bacterial supernatant of P. aeruginosa) were determined. Batch experiments were performed with cerium dioxide nanocrystals (NC) and V-BrPO to investigate the antifouling effects and the proposed biomimetic action of the NCs. Additionally, free active bromine (FAB) was used to elucidate the influence of reactive halogen species on QSMs and the mechanism of both catalysts. The batch experiments were performed for three QSMs and the formation of brominated, hydrolysed and oxidized TPs was identified with high resolution mass spectrometry (HRMS). For N-β-ketocaproyl-homoserine lactone (3-Oxo-C6-AHL), N-cis-tetradec-9Z-enoyl-homoserine lactone (C14:1-AHL) and 2-heptyl-4-quinolone (HHQ) a fast degradation and moiety-specific transformations were observed. In total, 17 TPs were identified at different levels of confidence. In addition, the same TPs were observed in the batch experiments with FAB as in the batch experiments with NC and V-BrPO. This shows on the one hand that the used cerium dioxide NCs led to a biomimetic transformation behaviour for QSMs of Gram-negative bacteria as known for the enzymes V-BrPO. And on the other hand, the results of the FAB experiments indicate that the catalytic processes take place via the formation of reactive halogen species. Furthermore, the transformation pathways for the QS groups unsaturated AHLs and alkyl quinolones have not yet been described in the literature and the knowledge about their degradation could be expanded with this study. Reactive halogen species also play a major role in disinfection processes with FAC. Additionally, FAC is one of the most potent inhibitors of QS compared to other disinfectants. However, a profound knowledge of degradation mechanisms of QSMs is lacking as well as knowledge on a possible impact on QS-controlled processes such as pathogenicity or biofilm formation. Therefore, the degradation behaviour of six representative QSMs of Gram-negative bacteria with FAC was investigated. A complete primary degradation was observed for para-coumaroyl AHL (pC-AHL), C14:1-AHL, HHQ and 3-Oxo-C14-AHL. In our study the primary kinetics and transformation pathways were studied in detail for pC-AHL, C14:1-AHL and HHQ. The reaction order varied between 1.19 (±0.07) (pC-AHL) to 1.62 (±0.13) (HHQ) at pH 7.0, indicating that different reactive species (e.g. hypochlorous acid and dichlorine monoxide) are involved in the transformation. In batch experiments with varying pH, the first-order rate constants show different trends for the investigated QSMs. For C14:1-AHL and HHQ, the first-order rate constants decreased from pH 6.0 to pH 8.5, which was mainly caused by the decreasing concentration of the reactive species hypochlorous acid and dichlorine monoxide in this pH range. In contrast, a maximum of the first order rate constant was observed for pC-AHL at pH 8.5 ranging from pH 6.0 to 10. In addition to the concentrations of reactive species, the phenol/phenolate ratio strongly influenced the first-order rate constants for pC-AHL. In total, 29 TPs (pH = 7.0) were identified by LC-ESI-HRMS and the related transformation pathways were proposed. The impact of FAC on QS can be expanded to the QSM groups unsaturated AHLs, quinolones and coumaroyl AHLs. Furthermore, the observed reaction mechanisms can be transferred to structurally similar QSMs such as 2-heptyl-1-hydroxyquinolin-4(1H)-one (HQNO) to further understand QS-controlled processes during chlorination. Finally, an interdisciplinary approach with the cooperation partners (microbiology and synthetic chemistry) of the University of Mainz was carried out for a profound understanding of the antifouling effect of cerium dioxide NCs in bacterial cultures. The developed methods and the results of the degradation experiments obtained in the previous studies were used to elucidate the processes also in a more complex biological system. Gram-negative specific inhibition of the biofilm formation was observed for synthesised and characterised cerium dioxide NCs for five different bacterial cultures. Due to the different QSMs used by the bacterial species, an influence on the AHL-system of the Gram-negative bacteria was suspected. In bioassays (Agrobacterium tumefaciens), a reduced QS activity was determined for the experiments with cerium dioxide NCs and measurements of the bromide concentration indicated the consumption of bromide. However, the detected brominated TPs from the previous studies could not be observed with LC-ESI-HRMS and LC-ESI-MS/MS in liquid-liquid extracts of the bacterial supernatant. Further biological degradation processes are here suspected. However, using non-target approaches, the catalytical bromination of HQNO was observed, which can be associated with QS. The bromination was verified by an additional batch experiment with HQNO and cerium dioxide NCs. The repression of the Pseudomonas quinolone signal (PQS) production and biofilm formation in P. aeruginosa through the formed brominated HQNO on surfaces with coating (cerium dioxide NCs) indicates the non-toxic nature of this strategy. The results of this thesis provide a new insight into the occurrence of QSMs and their transformation in relation to halogenation. In addition, the mechanistic investigations on cerium dioxide NCs show the possible relevance of these transformation processes. This new knowledge can be an important basis for the development of new sustainable antifouling agents and possibly for a better understanding and optimisation of disinfection processes.
Die vorliegende Arbeit untersucht die Forschungsfrage Welche fachspezifischen Faktoren beeinflussen den Einsatz digitaler Medien in der sportlichen Lehre von rheinland-pfälzischen Sportlehrkräften und Lehrkräftebildner:innen? Grundlage der Untersuchung bildet das Will-Skill-Tool-Modell zur Technologieintegration von Knezek et al. (2003), das drei zentrale Einflussfaktoren differenziert: (1) Die individuellen Haltungen und Einstellungen der Lehrperson gegenüber digitalen Medien (Will), (2) die subjektiv wahrgenommenen digitalisierungsbezogenen Kompetenzen (Skill) und (3) der Zugang zu technischer Infrastruktur (Tool).
Im Rahmen der Studie wurden 55 problemzentrierte leitfadengestützte Interviews mit rheinland-pfälzischen Sportlehramtsstudierenden, Lehramtsanwärter:innen, Lehrkräften, Seminarleiter:innen des Unterrichtsfaches Sport und Hochschuldozierenden, welche in der universitären Ausbildung von Sportlehrkräften involviert sind, durchgeführt.
Die Ergebnisse zeigen, dass die Beteiligten digitale Medien maßvoll einsetzen, wobei der Schwerpunkt auf der Nutzung von Videos und der Entlastung der Lehrperson liegt. Die Befragten stehen dem Einsatz digitaler Medien in der sportlichen Lehre überwiegend positiv gegenüber, empfinden jedoch häufig ein Spannungsfeld zwischen Mediennutzung und einem potenziellen Verlust an Bewegungszeit. Die erforderlichen digitalisierungsbezogenen Kompetenzen sollen aus Sicht der Be-fragten das Lernen mit Medien als Unterrichtswerkzeuge unterstützen, während kritisch und reflexive Aspekte kaum thematisiert werden. Im Vergleich zu Schulen wird die technische Ausstattung von Sporthallen als verbesserungswürdig wahrgenommen, was den Medieneinsatz hemmt. Die COVID-19-Pandemie hatte laut den Befragten einen signifikanten Einfluss auf den Medieneinsatz, die persönlichen Einstellungen und die individuellen digitalisierungsbezogenen Kompetenzen.
Die Ergebnisse deuten darauf hin, dass der Medieneinsatz nicht mehr ausschließlich als abhängige Variable betrachtet werden kann, sondern selbst Einfluss auf die Aspekte Will und Skill ausübt. Die spezifische Betrachtung der Modellkategorien legt nahe, dass dem Aspekt Tool für die sportliche Lehre eine besondere Bedeutung zukommt. Handlungsempfehlungen zur Förderung eines nachhaltigen und effektiven Einsatzes digitaler Medien in der sportlichen Lehre umfassen die verbindliche Integration digitaler Medien in Fachcurricula, die Gestaltung niederschwelliger Fortbildungen, die adäquate Ausstattung von Sporthallen und den Ausbau von Unterstützungsstrukturen.
Gender disparities in STEM (Science, Technology, Engineering, and Mathematics) fields remain a significant challenge, with women often underrepresented. Spatial abilities, particularly mental rotation (MR), are crucial for success in STEM, yet significant gender differences in these skills persist. This research aims to explore the factors contributing to these differences, focusing on emotional reactivity, self-concept, anxiety, and their impact on performance in mathematical and spatial tasks among primary school children. This research synthesizes findings from three related studies involving N=303 primary school students, consisting of 146 girls and 155 boys with a mean age=8.70 (SD=1.11) years. Data were collected through standardized questionnaires assessing self-concept, spatial and maths anxiety, and preferences for STEM subjects. Cognitive performance was evaluated using a computerized, novel Mental Rotation Task (nMRT) incorporating gender-congruent and neutral stimuli and various maths tasks correlating with mental rotation. Physiological responses were measured using galvanic skin response (GSR) to assess the impact of emotional reactivity on task performance. All data were collected in the classroom environment to increase ecological validity and generalizability of findings. Across studies, girls demonstrated higher maths and spatial anxiety, lower maths self-concept, and a lower preference for maths as a STEM subject compared to boys. These factors were significantly associated with performance differences in both maths and MR tasks. Higher emotional reactivity, as evidenced by GSR, and increased response time were associated with better scores on difficult items, that is, abstract stimuli rotated in-depth. Emotional reactivity also affected maths task completion times, with girls demonstrating lower physiological arousal linked to shorter processing time. Gender, subject preference, math self-concept and anxiety levels emerged as significant predictors of task performance on both maths and spatial tasks. The results underscore the influence of self concept, anxiety and physiological responses on cognitive performance, highlighting significant gender differences. Girls demonstrated higher subjective anxiety and physiological arousal during maths tasks. However, in the same group, lower emotional reactivity and maths anxiety served as protective influences, leading to improved scores and shorter completion times. Moreover, girls and tweens demonstrated lower maths self-concept and preference for maths, indicating that stereotype effects are already impacting their interest during primary school. These findings suggest that psychological factors play a crucial role in learning outcomes, particularly in STEM subjects. This integrated research contributes to a deeper understanding of how psychological factors such as self-concept, subjective anxiety but also physiological arousal and subject preferences affect mathematical and spatial performance in primary school children. The findings have practical implications for educators and policymakers, advocating for the development of strategies to enhance self-concept, manage anxiety and support emotional regulation, particularly in girls, fostering a supportive learning environment that mitigates the impact of stereotype threat. Enhanced self-efficacy and reduced anxiety thereby increase the likelihood of their engagement with maths, subsequently improving their performance and expanding their future career options
in STEM fields.
Population genetics investigates genetic diversity and its changes within and between populations over space and time. Genetic diversity is important for fitness, adaptive capacity, and the survival of populations and is influenced by several factors, such as mutation, selection, genetic drift and gene flow. Copper butterflies (Lycaena) are suitable for analysing structures influencing population connectivity as they potentially form more or less closed populations. However, very little is known about their genetic diversity and what influences it. Therefore, this thesis (1) provides newly developed microsatellite markers and uses genetic markers (2) to investigate genetic diversity across four different Lycaena species in the European Alps and to determine (3) which geographic and species specific factors influence population structure, (4) which large- and small-scale structures impact the population structure, (5) how natural and anthropogenic structures influence the population structure within an Alpine valley, and (6) whether and how genetic diversity changes over time. It was shown that the postglacial relict species L. helle has a relatively high genetic diversity compared to the other three species investigated. This suggests that L. helle is still able to adapt to environmental changes. Low genetic diversity was found in L. tityrus subalpinus, although high gene flow was found within one population of this species. High mountain ridges and large river valleys can act as dispersal barriers for Copper butterflies and thus have an impact on population structures. Here, dispersal ability as a species-specific factor also plays an important role, as some barriers are less likely to affect the population structure in the more mobile species L. virgaureae. Furthermore, forests, ravines and roads, but not small rivers, represent dispersal barriers for L. tityrus subalpinus within an Alpine valley. Finally, over ten years, the genetic diversity of L. hippothoe eurydame has decreased, whereas that of L. helle has remained stable. Against the backdrop of increasing global changes, it is important to understand the genomic underpinning of population structure and adaptation as well as to investigate and monitor whether populations are able to adapt to changing environmental conditions.
The digital transformation of the public sector and the development of suitable implementation mechanisms are currently major challenges in the area of E-Government. While Germany is one of the leading countries in the private sector in terms of digital offerings, the digital transformation processes in the public sector are progressing only slowly. In particular, compared to other European countries, German administrations offer few digital and interoperable services, which prevents them from catching up with a government-wide dig-ital transformation.
The aim of this dissertation is to investigate the reasons for the slow progress of digital transformation in the public sector and to understand why Germany is not making significant progress in the digitization of administrative services compared to other European member states. Furthermore, it aims to gradually build a comprehensive understanding of why digital transformation is not being driven, supported or applied in the public sector and what positive or negative factors ultimately prevent cross-organizational exchange.
The focus of this dissertation is on organizational and interdisciplinary collaboration in socio-technical systems and its influence on the digital transformation of public administrations. The investigation of science and practice is based on the principles of qualitative social research and qualitative content analysis according to Mayring. Deductive categories are systematically derived and supplemented by further inductive categories along the empirical investigation in the five case studies.
The identified phenomena are analyzed in a scientific explanatory model and described with the help of the holistic approach and the actor-network theory. On this basis, solutions are developed that can either prevent or at least reduce the influencing factors. An interdiscipli-nary approach that combines theoretical foundations from business informatics, administrative informatics/e-government and organizational science not only creates a comprehensive understanding of the problem, but also develops approaches for the scientific description of informatics phenomena with the help of social constructivist approaches.
During the development phase of plastic components, simulations are being used to an increasing extent. Against the background of product requirements and the inevitable necessity of conserving resources, the expanded use of simulation tools is an essential part of the solution. Among available methods, but so far underutilized with respect to real-life processes, is the molecular dynamics simulation. By the use of this method it is possible to visualize the physical processes occurring on the microscopic level, as e.g. those that arise during plastics processing. This thesis examines how boundary conditions, which mimic the extrusion blow molding process, affect the behavior of polyethylene on the microscopic level. A mesoscopic model (coarse-graining) is applied to describe the polymer. Initially, this model is verified by determining material properties. The uniaxial tensile test is modeled on the micro-scale to identify parameters such as the elastic modulus, yield stress, and Poisson’s ratio. Additionally, thermal properties, particularly those characterizing the crystallization behavior, are identified. The objective of these investigations is the microscopic observation and quantification of effects that occur during dynamic stretching and crystallization processes. The calculated properties show good agreement with the experimental data, especially regarding the thermal parameters. Qualitatively, the stress-strain behavior is reproduced in alignment with experimentally observed results. However, the short time scale of the simulation models leads to micromechanical behavior that is more extreme than what is monitored on a macroscopic level. By extending the simulation models, biaxial stretching processes are simulated. These stretching processes resemble the situation during the inflation of the parison in the extrusion blow molding process. The examination of various cooling conditions, particularly by the use of mold constraints, is another focus of the investigations. The analysis of the biaxially stretched simulations reveals that disentanglement processes during stretching dominate the further development of polymer systems. It is possible to quantify the dynamics of crystallization processes depending on the degree of stretching and cooling conditions through various parameters (distribution of entanglement points, local orientations). The results indicate that coarse-grained molecular dynamics simulations are able to significantly enhance the micromechanical understanding of local events occurring during plastic processing.
Cross Cultural Adaptation of Design Thinking in Entrepreneurship Higher Education in Indonesia
(2024)
Entrepreneurship and entrepreneurship education have expanded together, and their conceptual and methodological challenges do not prevent the implementation of entrepreneurial education in educational contexts. The desire for a global workforce that can handle uncertainties and solve problems that cannot be solved by pure analytical inquiry drives the rapidly expanding number of educational programs and activities that are design-based. A growing number of educational programs for entrepreneurs increasingly incorporate design-based methods. However, design thinking-based theoretical assumptions may also be lacking. Despite growing academic interest in design thinking and entrepreneurship education, little is known about design thinking in higher entrepreneurship education, especially in Eastern nations. A Western teaching method, entrepreneurial design thinking may be adapted to many cultures. In this instance, the West has established entrepreneurship education as a respectable study subject and teaching practice in higher education over the past 40 years. The Eastern nations' occurrence varies, including Indonesia. Indonesia is an intriguing research subject since it has over 50% youth due to its abundant natural resources. However, it needs more opportunity-based entrepreneurs and requires assistance in implementing entrepreneurship education with a more innovative, design-based, and successful method. Entrepreneurial design thinking fulfills this demand. Indonesian students and teachers' norm-based attitudes and cultural mindsets towards a new western creative method may hinder entrepreneurial design thinking's acceptance. The literature review found that Indonesian university students are collaborative, compassionate, and practical, like design thinkers. However, they may also be risk-averse, self-restrained, and dependent on teachers as stereotypical Asians. Classroom space, educators' design thinking competence, and university or institution support are further barriers. Additional study into these challenges is needed to adapt design thinking to Indonesian entrepreneurial higher education culturally.
Based on the above research needs, the purpose of this research endeavor is to look into the cultural nuances of the design thinking technique for entrepreneurial higher education and postulate how it could be adapted to other cultures, especially in Indonesia. This thesis uses deductive and qualitative case-study research methods. In particular, the latter used thematic analysis (Braun & Clarke, 2006; Terry & Hayfield, 2021) as the data analysis technique to provide a means and tools for understanding from interviews, class observation, and literature studies. Since this thesis follows the constructivist-relativist research paradigm, it explores contextual and cultural differences in Indonesian entrepreneurship education and its potential and obstacles to adapt the Western teaching methodology of entrepreneurial design thinking in higher education. In summary, this study searches for elements that might aid or hinder the cross-cultural adaption of entrepreneurial design thinking. This research wants to understand how cross-cultural adaptability fits into entrepreneurial design thinking research, especially for Indonesia. This thesis aims to provide new theoretical insights and practical advice on adapting entrepreneurial design thinking from Western to Eastern cultures.
From the findings, this thesis concluded at least seven educational value differentials before adaptation from the exhaustive literature and case study evaluations. For Indonesian entrepreneurship higher education institutions to use entrepreneurial design thinking, they must consider educational culture, technological infrastructure, language, primary audience, learning and teaching style, reasoning patterns, and social-cultural environment. This study provides four practical adaptation recommendations: socialization, externalization, combination, and internalization. Finally, this research demonstrated that cross-cultural adaption of entrepreneurial design thinking in Indonesia might be difficult but worthwhile. This thesis' case study, "School of Business Management – Bandung Institute of Technology (SBM ITB)", showed that Indonesian entrepreneurial higher education might use design thinking as a teaching approach. All stakeholders must improve internally and publicly. Thus, this study recommended integrating most Indonesian higher education institutions' entrepreneurship teaching approaches with a "student-centered" approach that stresses business mentorship, uses design thinking tools and processes, and links them to students' entrepreneurial initiatives.
To summarize, this research contributes to the field since it draws on and combines the findings of several other fields of study, including entrepreneurial education, design thinking, and cross-cultural adaptation. This study stepped out of the "usual and proper" pedagogical ruts to investigate "non-human" cross-cultural adaptability. It has attempted to apply these ideas to a real-world, unique case study in a developing nation (in this case, Indonesia).
The political targets for CO2 reduction in industrial processes are leading to a technological change in the area of pig iron production. In future, pig iron will be produced by using the direct reduction process instead of the blast furnace process. Direct reduction plants are currently operated with natural gas, this is to be replaced by hydrogen in the future in order to meet the climate targets. Within this work, the influence of hydrogen-containing atmospheres on currently used refractory materials from the Al2O3-SiO2 system was investigated. An experiment was developed to simulate the corrosion of refractory materials in the laboratory under realistic test conditions. Taking into account the atmosphere, the temperature and the sample material, a variety of practical corrosion tests were carried out. By applying a comprehensive analysis strategy, relevant corrosion effects on the materials were subsequently described as a result of the gas composition. The test temperature was in the range of 716 °C < T < 1150 °C. Physical and chemical-mineralogical tests were used to investigate the corrosion effects. In addition, the intensity of the corrosion effects was evaluated based on the gas compositions used. Pure hydrogen atmospheres in particular led to strong gas corrosion, while the presence of water vapor inhibited the chemical reactions. The mixture of methane and hydrogen can create an aggressive H2 / CO atmosphere, which also can lead to the formation of solid carbon. This phenomenon changes the possible causes of damage to refractory material; the crystallization pressure of carbon inside the structure of the refractory can also contribute to material failure. Furthermore, the corrosion reactions could be described by coupling imaging analysis methods and element determination. It was shown that, in contrast to the general opinion in the state of the art, there was not exclusively a decrease in SiO2-amount. Several reactions took place in the investigated, industrially used materials, which led to the local chemical attack of SiO2 (silicate glass phase) and caused a parallel crystallization of cristobalite. The chemical attack of hydrogen on the silicate glass phase can be defined as the primary corrosion reaction in the range of 716 °C < T < 1150 °C in a pure hydrogen atmosphere. In addition, the reaction kinetics as a function of temperature were experimentally investigated and described. Based on these analyses, material properties can be defined that are particularly suitable for the future use of defined refractory qualities within reduction processes.
Die vorliegende Dissertation hat sich unter dem Titel >>„Woher soll ich denn vorher wissen, ob ich den Job liebe?“ – Eine qualitative Längsschnitt-Studie zur Differenzierung der Phasenstruktur vorliegender Modelle beruflicher Orientierung anhand von Jugendlichen aus drei kontrastierenden institutionellen Ausgangslagen<< dem Erkenntnisinteresse gewidmet, Modelle zur beruflichen Orientierung anhand eines ethnografischen Zugangs aus der Perspektive unterschiedlicher institutioneller Settngs weiterzuentwickeln, um der Komplexität gegenwärtiger Lebenswelten besser gerecht zu werden. Dabei wurde unter Betrachtung von Berufsorientierungsaspekten als Forschungsgegenstand sowie unter Betrachtung der Gestalt der Berufsorientierung als Forschungsfeld der Fragestellung nachgegangen, inwiefern sich das in der Debatte zentrale Sechs-Phasenmodell der Berufswahl nach Herzog et. al. (2006) im Licht ethnografischer Forschung, welche die Perspektiven Jugendlicher eines allgemeinbildenden Gymnasiums, eines beruflichen Gymnasiums sowie eines Freiwilligen Sozialen Jahres umfasst, ausdifferenzieren lässt. Dabei wurde die Grounded Theory-Methodologie als Forschungsstil zugrunde gelegt, der wiederum im Rahmen der Datenerhebung die Ethnografie, im Rahmen der Datenanalyse die Grounded Theory untergeordnet wurde.
Als zentrales Untersuchungsergebnis lässt sich zum einen aufführen, dass das bestehende Berufswahlmodell deutlich modifiziert, ausdifferenziert und folglich erweitert werden konnte. Mit dieser Erweiterung ist eine Spezifikation dahingehend verbunden, dass viele Komponenten und Ebenen hinzugekommen sind, die bei dem ursprünglichen Modell nicht bedacht waren, im Gegenzug jedoch auch solche Komponenten gestrichen und als irrelevant deklariert wurden, die sich anhand der Untersuchungsdaten nicht zu bestätigen wussten. So konnte ein Neun-Phasenmodell der Berufsorientierung in Gestalt eines Ablaufdiagramms
entstehen, das den Prozessverlauf beruflicher Orientierung anschaulich in Phasen eingebettet darzustellen vermag. Dabei ist es gelungen, das Modell derart auszugestalten, dass es institutionsübergreifend anwendbar und nicht lediglich auf eine bestimmte institutionelle Ausgangslage beschränkt ist. Zum anderen kann statuiert werden, dass das vorliegende neunphasige Modell vor allem Phasen der Orientierungslosigkeit und der Desorientierung, des Entscheidungsaufschubs, der Überprüfung und der Überbrückung sowie der Um- und Neuorientierung explizit zu nutzen weiß, um diejenigen Situationen zu berücksichtigen, die den beruflichen Orientierungsprozess der Untersuchungsteilnehmenden aus allen drei
institutionellen Ausgangslagen maßgeblich geprägt haben.
The goal of this PhD thesis is to investigate possibilities of using symbol elimination for solving problems over complex theories and analyze the applicability of such uniform approaches in different areas of application, such as verification, knowledge representation and graph theory. In the thesis we propose an approach to symbol elimination in complex theories that follows the general idea of combining hierarchical reasoning with symbol elimination in standard theories. We analyze how this general approach can be specialized and used in different areas of application.
In the verification of parametric systems it is important to prove that certain safety properties hold. This can be done by showing that a property is an inductive invariant of the system, i.e. it holds in the initial state of the system and is invariant under updates of the system. Sometimes this is not the case for the condition itself, but for a stronger condition it is. In this thesis we propose a method for goal-directed invariant strengthening.
In knowledge representation we often have to deal with huge ontologies. Combining two ontologies usually leads to new consequences, some of which may be false or undesired. We are interested in finding explanations for such unwanted consequences. For this we propose a method for computing interpolants in the description logics EL and EL⁺, based on a translation to the theory of semilattices with monotone operators and a certain form of interpolation in this theory.
In wireless network theory one often deals with classes of geometric graphs in which the existence or non-existence of an edge between two vertices in a graph relies on properties on their distances to other nodes. One possibility to prove properties of those graphs or to analyze relations between the graph classes is to prove or disprove that one graph class is contained in the other. In this thesis we propose a method for checking inclusions between geometric graph classes.
In international business relationships, such as international railway operations, large amounts of data can be exchanged among the parties involved. For the exchange of such data, a limited risk of being cheated by another party, e.g., by being provided with fake data, as well as reasonable cost and a foreseeable benefit, is expected. As the exchanged data can be used to make critical business decisions, there is a high incentive for one party to manipulate the data in its favor. To prevent this type of manipulation, mechanisms exist to ensure the integrity and authenticity of the data. In combination with a fair exchange protocol, it can be ensured that the integrity and authenticity of this data is maintained even when it is exchanged with another party. At the same time, such a protocol ensures that the exchange of data only takes place in conjunction with the agreed compensation, such as a payment, and that the payment is only made if the integrity and authenticity of the data is ensured as previously agreed. However, in order to be able to guarantee fairness, a fair exchange protocol must involve a trusted third party. To avoid fraud by a single centralized party acting as a trusted third party, current research proposes decentralizing the trusted third party, e.g., by using a distributed ledger based fair exchange protocol. However, for assessing the fairness of such an exchange, state-of-the-art approaches neglect costs arising for the parties conducting the fair exchange. This can result in a violation of the outlined expectation of reasonable cost, especially when distributed ledgers are involved, which are typically associated with non-negligible costs. Furthermore, the performance of typical distributed ledger-based fair exchange protocols is limited, posing an obstacle to widespread adoption.
To overcome the challenges, in this thesis, we introduce the foundation for a data exchange platform allowing for a fully decentralized fair data exchange with reasonable cost and performance. As a theoretical foundation, we introduce the concept of cost fairness, which considers cost for the fairness assessment by requesting that a party following the fair exchange protocol never suffers any unilateral disadvantages. We prove that cost fairness cannot be achieved using typical public distributed ledgers but requires customized distributed ledger instances, which usually lack complete decentralization. However, we show that the highest unilateral cost are caused by a grieving attack.
To allow fair data exchanges to be conducted with reasonable cost and performance, we introduce FairSCE, a distributed ledger-based fair exchange protocol using distributed ledger state channels and incorporating a mechanism to protect against grieving attacks, reducing the possible unilateral cost that have to be covered to a minimum. Based on our evaluation of FairSCE, the worst-case cost for data exchange, even in the presence of malicious parties, is known, which allows an estimate of the possible benefit and, thus, the preliminary estimate of economic utility. Furthermore, to allow for an unambiguous assessment of the correct data being transferred while still allowing for sensitive parts of the data to be masked, we introduce an approach for the hashing of hierarchically structured data, which can be used to ensure integrity and authenticity of the data being transferred.
Degenerative changes in the spine as well as back pain can be considered a common ailment. Incorrect loading of the lumbar spine structures is often considered as one of the factors that can accelerate degenerative processes, leading to back pain. For example, a degenerative change could be the occurrence of spinal stenosis following spondylolisthesis. Surgical treatment of spinal stenosis mainly focuses on decompressing the spinal canal with or without additional fusion through dorsal spondylodesis. There are differing opinions on whether fusion along with decompression provides potential benefits to patients or represents an overtreatment. Both conventional therapies and surgical methods aim to restore a “healthy” (or at least pain-free) distribution of load. Surprisingly little is known about the interindividual variability of load distribution in “healthy” lumbar spines. Since medical imaging does not provide information on internal forces, computer simulation of individual patients could be a tool to gain a set of new decision criteria for these cases. The advantage lies in calculating the internal load distribution, which is not feasible in in-vivo studies, as measurements of internal forces in living subjects are ethically and partially technically unfeasible. In the present research, the forward dynamic approach is used to calculate load distribution in multi-body models of individual lumbar spines. The work is structured into three parts: (I) Load distribution is quantified depending on the individual curvature of the lumbar spine. (II) Confidence intervals of the instantaneous center of rotation over time are determined, with which the motion behavior of healthy lumbar spines can be described. (III) Lastly, the effects of decompression surgeries on the load distribution of lumbar spines are determined.
The biodegradable polymers polylactic acid (PLA) and polyhydroxybutyrate (PHB) produced from renewable raw materials were coated with hydrogenated amorphous carbon layers (a-C:H) at different deposition angles with various thicknesses as part of this thesis. Similar to conventional polymers, biopolymers often have unsuitable surface properties for industrial purposes, e.g. low hardness. For some applications, it is therefore necessary and advantageous to modify the surface properties of biopolymers while retaining the main properties of the substrate material. A suitable surface modification is the deposition of thin a-C:H layers. Their properties depend essentially on the sp² and sp³ hybridization ratio of the carbon atoms and the content of hydrogen atoms. The sp²/sp³ ratio was to be controlled in the present work by varying the coating geometry. Since coatings at 0°, directly in front of the plasma source, contain a higher percentage of sp³ and indirectly coated (180°) a higher amount of sp², it is shown in this work that it is possible to control the sp²/sp³ ratio. For this purpose, the samples are placed in front of the plasma source at angles of 0, 30, 60, 90, 120, 150 and 180° and coated for 2.5, 5.0, 7.5 and 10.0 minutes. For the angles 0°, the layer thicknesses were 25, 50, 75 and 100 nm. The a-C:H layers were all deposited using radio-frequency plasma-enhanced chemical vapor deposition and acetylene as C and H sources after being pretreated with an oxygen plasma for 10 minutes. Following the O₂ treatment and the a-C:H deposition, the surfaces are examined using macroscopic and microscopic measurement methods and the data is then analyzed. The surface morphology is recorded using scanning electron microscopy and atomic force microscopy. In addition, data on the stability of the layer and the surface roughness can be collected. Contact angle (CA) measurements are used to determine not only the wettability, but also the contact angle hysteresis by pumping the drop volume up and down. By measuring the CA with different liquids and comparing them, the surface free energy (SFE) and its polar and disperse components are determined. The changes in barrier properties are verified by water vapor transmission rate tests (WVTR). The chemical analysis of the surface is carried out on the one hand by Fourier transform infrared spectroscopy with specular reflection and on the other hand by synchrotron-supported techniques such as near-edge X-ray absorption fine structure and X-ray photoelectron spectroscopy. When analyzing the surfaces after the O₂ treatment, which was initially assumed to serve only to clean and activate the surface for the a-C:H coating, it was found that the changes were more drastic than originally assumed. For example, if PLA is treated at 0° for 10 minutes, the roughness increases fivefold. As the angle increases, it decreases again until it returns to the initial value at 180°. This can be recognized to a lesser extent with PHB at 30°. For both polymers, it can be shown that the polar fraction of the SFE increases. In the WVTR, a decrease in permeability can be observed for PLA and an increase in the initial value for PHB. The chemical surface analysis shows that the O₂ treatment has little effect on the surface bonds. Overall, it can be shown in this work that the O₂ treatment has an effect on the properties of the surface and cannot be regarded exclusively as a cleaning and activation process. With direct a-C:H coating (at 0°), a layer failure due to internal stress can be observed for both PLA and PHB. This also occurs with PHB at 30°, but to a lesser extent. Permeability of the polymers is reduced by 47% with a five-minute coating and the layer at 10.0 minutes continues to have this effect despite cracks appearing. The application of a-C:H layers shows a dominance of sp³ bonds for both polymer types with direct coating. This decreases with increasing angle and sp² bonds become dominant for indirect coatings. This result is similar for all coating thicknesses, only the angle at which the change of the dominant bond takes place is different. It is shown that it is possible to control the surface properties by an angle-dependent coating and thus to control the ratio sp²/sp³.
How to begin? This short question addresses a problem that is anything but simple, especially when regarding something as sophisticated and multilayered as musical theatre. However, scholars of this vast research area have mostly neglected this question so far. This study analyses and compares the initial sections of late Victorian popular musical theatre and is therefore a contribution to several fields of research: the analysis of initial sections of musical theatre in general, the analysis of the music of popular musical theatre in particular, and therefore operetta studies. The 1890s are especially interesting times for popular musical theatre in London: The premiered works include the last collaborations of Gilbert and Sullivan as well as offshoots of Savoy opera; but the so-called ‘naughty nineties’ also saw the emergence of a new genre, musical comedy, which captured the late Victorian zeitgeist like no other. This new form of theatrical entertainment was carefully and consciously constructed and promoted as modern and fashionable, walking a fine line between respectability and mildly risqué excitement.
Because a deep understanding of the developments and new tendencies concerning popular musical theatre in the 1890s is crucial in order to interpret differences as well as similarities, the analyses of the opening numbers are preceded by a detailed discussion of the relevant genres: comic opera, musical comedy, musical play and operetta. Since the producers of the analysed works wanted to distance themselves from former and supposedly old-fashioned traditions, this book also considers influences from their British predecessors, but also from Viennese operetta and French opéra bouffe.
Nanoparticles are sensitive and robust systems; they are particularly reactive due to their large surface area and have properties that the bulk material does not have. At the same time, the production of nanoparticles is challenging, because even with the same parameters and conditions, the parameters can vary slightly from run to run. In order to avoid this, this work aims to develop a continuous synthesis in the microjet reactor for nanoceria. The aim is to obtain monodisperse nanoparticles that can be used in biosensors.
This work focuses on two precipitation syntheses with the intermediate steps of cerium carbonate and cerium hydroxide, as well as a microemulsion synthesis for the production of nanoceria. The cerium oxide nanoparticles are compared using different characterisation and application methods. The synthesised nanoparticles will be characterised with respect to their size, stability, chemical composition and catalytic capabilities, by electron microscopy, X-ray diffraction, Raman spectroscopy and photoelectron spectroscopy.
The biosensor systems to evaluate the nanoceria are designed to detect histamine and glucose or hydrogen peroxide, which are resulting from the oxidation of histamine and glucose. Hydrogen peroxide and glucose are detected by an electrochemical sensor and histamine by a colorimetric sensor system.
In der vorliegenden Dissertation mit dem Titel "Blickanalysen bei mentalen Rotationsaufgaben" wird eine Analyse der visuellen Verarbeitungsprozesse bei mentalen Rotationsaufgaben mittels Eye-Tracking-Technologie durchgeführt, um die zugrundeliegenden kognitiven Prozesse und Strategien, die bei der Lösung dieser Aufgaben angewandt werden, zu untersuchen. Ein Anliegen dieser Arbeit ist es, die Problemstellung zu adressieren, wie individuelle Unterschiede, insbesondere geschlechtsspezifische Differenzen in den Blickmustern, die visuelle Verarbeitung und Leistung bei mentalen Rotationsaufgaben beeinflussen. Hierzu wurden drei Studien durchgeführt, die nicht nur die Identifikation von Blickmustern und die Analyse der Leistungsunterschiede in Bezug auf Geschlecht umfassen, sondern auch die Korrelation zwischen Blickverhalten und Leistung untersuchen. Die Ergebnisse dieser Forschung bieten Einblicke in die Mechanismen der visuellen und kognitiven Verarbeitung bei mentalen Rotationsaufgaben und heben die Bedeutung des Eye-Tracking als Forschungsinstrument in der kognitiven Psychologie hervor, um ein umfassendes Verständnis der Einflussfaktoren auf räumliches Denken und Problemlösungsstrategien zu erlangen.
Classical music has played a central role in German music education since at least the second half of the 20th century. However, in more recent music pedagogical discourse, classical music remains a controversial topic. But what do music teachers think about classical music as a subject for music education? This topic has not yet been systematically researched in German-speaking music education.
In this qualitative-empirical study, eight semi-structured interviews were conducted to address the question of how music teachers perceive classical music in music education. The data was evaluated using the Grounded Theory Methodology. The theory developed from the study indicates that music teachers have varying objectives when using classical music in music education. However, they generally consider it unfamiliar to their students. To address this situation, music teachers develop various methods and strategies. These can be categorized into three approaches for dealing with the unfamiliarity of classical music: avoidance, reduction/relativization, and utilization.
The study's findings are contextualized within the framework of foreignness theory, music didactics, and transformational educational theory. This dissertation contributes to the field of music education in classical music, laying the groundwork for further theoretical, empirical, and didactic research.
Diese Dissertation widmet sich der inhaltsanalytischen, quantitativen Analyse der Kompilation Disney Princess durch die Anwendung der Theorie des male gaze von Laura Mulvey, welche sie in Visual Pleasure and Narrative Cinema (1975) sowie Afterthoughts on `Visual Pleasure and Narrative Cinema‘ inspired by King Vidor´s Duel in the Sun (1946) (1981) darstellte.
Die Autorin der Dissertation nutzt die quantitative Inhaltsanalyse nach Patrick Rössler, um die Filme der Kompilation Disney Princess aus den Jahren 1937 bis 2016 sowie den Film Die Eiskönigin (2013) auf die Darstellung der weiblich und männlich gelesenen Filmfiguren im Hinblick auf die Körperproportionen, den Grad ihrer Aktivität und den Umfang ihrer Präsenz sowie das Geschlecht der Filmmitarbeiter:innen zu untersuchen.
Focusing on the triangulation of detective fiction, masculinity studies and disability studies, "Investigating the Disabled Detective – Disabled Masculinity and Masculine Disability in Contemporary Detective Fiction" shows that disability challenges common ideals of (hegemonic) masculinity as represented in detective fiction. After a theoretical introduction to the relevant focal points of the three research fields, the dissertation demonstrates that even the archetypal detectives Dupin and Holmes undermine certain nineteenth-century masculine ideals with their peculiarities. Shifting to contemporary detective fiction and adopting a literary disability studies perspective, the dissertation investigates how male detectives with a form of neurodiversity or a physical impairment negotiate their masculine identity in light of their disability in private and professional contexts. It argues that the occupation as a detective supports the disabled investigator to achieve ‘masculine disability’. Inversing the term ‘disabled masculinity’, predominantly used in research, ‘masculine disability’ introduces a decisively gendered reading of neurodiversity and (acquired) physical impairment in contemporary detective fiction. The term implies that the disabled detective (re)negotiates his masculine identity by implementing the disability in his professional investigations and accepting it as an important, yet not defining, characteristic of his (gender) identity. By applying this approach to five novels from contemporary British and American detective fiction, the dissertation demonstrates that masculinity and disability do not negate each other, as commonly assumed. Instead, it emphasises that disability allows the detective, as much as the reader, to rethink masculinity.
Empirical studies in software engineering use software repositories as data sources to understand software development. Repository data is either used to answer questions that guide the decision-making in the software development, or to provide tools that help with practical aspects of developers’ everyday work. Studies are classified into the field of Empirical Software Engineering (ESE), and more specifically into Mining Software Repositories (MSR). Studies working with repository data often focus on their results. Results are statements or tools, derived from the data, that help with practical aspects of software development. This thesis focuses on the methods and high order methods used to produce such results. In particular, we focus on incremental methods to scale the processing of repositories, declarative methods to compose a heterogeneous analysis, and high order methods used to reason about threats to methods operating on repositories. We summarize this as technical and methodological improvements. We contribute the improvements to methods and high-order methods in the context of MSR/ESE to produce future empirical results more effectively. We contribute the following improvements. We propose a method to improve the scalability of functions that abstract over repositories with high revision count in a theoretically founded way. We use insights on abstract algebra and program incrementalization to define a core interface of highorder functions that compute scalable static abstractions of a repository with many revisions. We evaluate the scalability of our method by benchmarks, comparing a prototype with available competitors in MSR/ESE. We propose a method to improve the definition of functions that abstract over a repository with a heterogeneous technology stack, by using concepts from declarative logic programming and combining them with ideas on megamodeling and linguistic architecture. We reproduce existing ideas on declarative logic programming with languages close to Datalog, coming from architecture recovery, source code querying, and static program analysis, and transfer them from the analysis of a homogeneous to a heterogeneous technology stack. We provide a prove-of-concept of such method in a case study. We propose a high-order method to improve the disambiguation of threats to methods used in MSR/ESE. We focus on a better disambiguation of threats, operationalizing reasoning about them, and making the implications to a valid data analysis methodology explicit, by using simulations. We encourage researchers to accomplish their work by implementing ‘fake’ simulations of their MSR/ESE scenarios, to operationalize relevant insights about alternative plausible results, negative results, potential threats and the used data analysis methodologies. We prove that such way of simulation based testing contributes to the disambiguation of threats in published MSR/ESE research.
Sind Menschen von einer Pflegebedürftigkeit in Deutschland betroffen, so regelt der durch § 14 SGB XI festgeschriebene Pflegebedürftigkeitsbegriff den Zugang zu Leistungen der Pflegeversicherung. Der Pflegebedürftigkeitsbegriff ist dabei ein normativ gesetzter und basiert bislang nicht auf empirischen Studien aus dem Bereich der Pflege und der Pflegewissenschaft. Durch seine gesetzliche Fundierung lenkt er die Bedingungen und Strukturen, unter welchen Pflegeleistungen in Deutschland von Pflegefachpersonen erbracht werden. Weiterhin ist davon auszugehen, dass die Pflegefachpersonen durch ihre professionelle Sozialisierung einen fachlichen Fokus auf das Konstrukt der Pflegebedürftigkeit legen, welcher sich vom Pflegebedürftigkeitsbegriff unterscheidet und strukturell nicht in die Leistungsbemessung einfließt. Daraus ergeben sich Aspekte einer pflegerischen Unter- und Überversorgung.
Die vorliegende Ph.D.-Thesis verfolgt das Anliegen, die Herausforderungen des Pflegebedürftigkeitsbegriffs in Deutschland aufzuzeigen, indem die Aspekte der Pflegebedürftigkeit von Pflegefachpersonen im ambulanten Setting im Hinblick auf deren Interaktion mit pflegebedürftigen Menschen empirisch erfasst und zu einem theoretischen Konzept ausgearbeitet werden. Zur methodischen Bearbeitung des Forschungsinteresses werden problemzzentrierte Interviews mit ambulanten Pflegefachpersonen geführt, die mit Rückbezug auf den Symbolischen Interaktionismus nach Herbert Blumer unter methodologischen und methodischen Gesichtspunkten mittels einer Grounded Theory nach Kathy Charmaz sowie Juliet Corbin und Anselm Strauss erhoben und ausgewertet werden. Dabei kommt ein reflexives-konstruktivistisches Forschen und Schreiben als Konsequenz der epistemologisch-methodologischen Fundierung der Autorin zur Anwendung.
Die erarbeitete Theorie beschreibt die Herausforderungen der Pflegebedürftigkeit aus Sicht der befragten Pflegefachpersonen. So werden in der Kernkategorie Aushandlungsprozesse in den Bereichen Nähe und Distanz, Anwaltschaft und Verantwortungsüberlassung sowie Ethos und Technokratie beschrieben. Sämtliche Aspekte zeigen auf, inwiefern der gesetzliche Pflegebedürftigkeitsbegriff zu Herausforderungen innerhalb der pflegerischen Arbeit führt. Die Ph.D.-Thesis liefert mit ihren Ergebnissen einen Beitrag zur Einordnung und Relevanz pflegerischer Beziehungsarbeit im Hinblick auf herrschende Rahmenbedingungen der Pflegebedürftigkeit und zeigt auf, inwiefern sich Interaktion und Kommunikation der Akteur*innen vor dem Anspruch individueller Pflege und dem deutschen ambulanten Pflegesystem wechselseitig bedingen. Sie liefert damit einen professionell und empirisch begründeten Ansatz für die Einschätzung und Bearbeitung von pflegefachlich erlebter Pflegebedürftigkeit.
In the last years, the public interest in epidemiology and mathematical modeling of disease spread has increased - mainly caused by the COVID-19 pandemic, which has emphasized the urgent need for accurate and timely modelling of disease transmission. However, even prior to that, mathematical modelling has been used for describing the dynamics and spread of infectious diseases, which is vital for developing effective interventions and controls, e.g., for vaccination campaigns and social restrictions like lockdowns. The forecasts and evaluations provided by these models influence political actions and shape the measures implemented to contain the virus.
This research contributes to the understanding and control of disease spread, specifically for Dengue fever and COVID-19, making use of mathematical models and various data analysis techniques. The mathematical foundations of epidemiological modelling, as well as several concepts for spatio-temporal diffusion like ordinary differential equation (ODE) models, are presented, as well as an originally human-vector model for Dengue fever, and the standard (SEIR)-model (with the potential inclusion of an equation for deceased persons), which are suited for the description of COVID-19. Additionally, multi-compartment models, fractional diffusion models, partial differential equations (PDE) models, and integro-differential models are used to describe spatial propagation of the diseases.
We will make use of different optimization techniques to adapt the models to medical data and estimate the relevant parameters or finding optimal control techniques for containing diseases using both Metropolis and Lagrangian methods. Reasonable estimates for the unknown parameters are found, especially in initial stages of pandemics, when little to no information is available and the majority of the population has not got in contact with the disease. The longer a disease is present, the more complex the modelling gets and more things (vaccination, different types, etc.) appear and reduce the estimation and prediction quality of the mathematical models.
While it is possible to create highly complex models with numerous equations and parameters, such an approach presents several challenges, including difficulties in comparing and evaluating data, increased risk of overfitting, and reduced generalizability. Therefore, we will also consider criteria for model selection based on fit and complexity as well as the sensitivity of the model with respect to specific parameters. This also gives valuable information on which political interventions should be more emphasized for possible variations of parameter values.
Furthermore, the presented models, particularly the optimization using the Metropolis algorithm for parameter estimation, are compared with other established methods. The quality of model calculation, as well as computational effort and applicability, play a role in this comparison. Additionally, the spatial integro-differential model is compared with an established agent-based model. Since the macroscopic results align very well, the computationally faster integro-differential model can now be used as a proxy for the slower and non-traditionally optimizable agent-based model, e.g., in order to find an apt control strategy.
Leichte Sprache (LS, easy-to-read German) is a simplified variety of German. It is used to provide barrier-free texts for a broad spectrum of people, including lowliterate individuals with learning difficulties, intellectual or developmental disabilities (IDD) and/or complex communication needs (CCN). In general, LS authors are proficient in standard German and do not belong to the aforementioned group of people. Our goal is to empower the latter to participate in written discourse themselves. This requires a special writing system whose linguistic support and ergonomic software design meet the target group’s specific needs. We present EasyTalk a system profoundly based on natural language processing (NLP) for assistive writing in an extended variant of LS (ELS). EasyTalk provides users with a personal vocabulary underpinned with customizable communication symbols and supports in writing at their individual level of proficiency through interactive user guidance. The system minimizes the grammatical knowledge needed to produce correct and coherent complex contents by intuitively formulating linguistic decisions. It provides easy dialogs for selecting options from a natural-language paraphrase generator, which provides context-sensitive suggestions for sentence components and correctly inflected word forms. In addition, EasyTalk reminds users to add text elements that enhance text comprehensibility in terms of audience design (e.g., time and place of an event) and improve text coherence (e.g., explicit connectors to express discourse-relations). To tailor the system to the needs of the target group, the development of EasyTalk followed the principles of human-centered design (HCD). Accordingly, we matured the system in iterative development cycles, combined with purposeful evaluations of specific aspects conducted with expert groups from the fields of CCN, LS, and IT, as well as L2 learners of the German language. In a final case study, members of the target audience tested the system in free writing sessions. The study confirmed that adults with IDD and/or CCN who have low reading, writing, and computer skills can write their own personal texts in ELS using EasyTalk. The positive feedback from all tests inspires future long-term studies with EasyTalk and further development of this prototypical system, such as the implementation of a so-called Schreibwerkstatt (writing workshop)
In a world where language defines the boundaries of one's understanding, the words of Austrian philosopher Ludwig Wittgenstein resonate profoundly. Wittgenstein's assertion that "Die Grenzen meine Sprache bedeuten die Grenzen meiner Welt" (Wittgenstein 2016: v. 5.6) underscores the vital role of language in shaping our perceptions. Today, in a globalized and interconnected society, fluency in foreign languages is indispensable for individual success. Education must break down these linguistic barriers, and one promising approach is the integration of foreign languages into content subjects.
Teaching content subjects in a foreign language, a practice known as Content Language Integrated Learning (CLIL), not only enhances language skills but also cultivates cognitive abilities and intercultural competence. This approach expands horizons and aligns with the core principles of European education (Leaton Gray, Scott & Mehisto 2018: 50). The Kultusministerkonferenz (KMK) recognizes the benefits of CLIL and encourages its implementation in German schools (cf. KMK 2013a).
With the rising popularity of CLIL, textbooks in foreign languages have become widely available, simplifying teaching. However, the appropriateness of the language used in these materials remains an unanswered question. If textbooks impose excessive linguistic demands, they may inadvertently limit students' development and contradict the goal of CLIL.
This thesis focuses on addressing this issue by systematically analyzing language requirements in CLIL teaching materials, emphasizing receptive and productive skills in various subjects based on the Common European Framework of Reference. The aim is to identify a sequence of subjects that facilitates students' language skill development throughout their school years. Such a sequence would enable teachers to harness the full potential of CLIL, fostering a bidirectional approach where content subjects facilitate language learning.
While research on CLIL is extensive, studies on language requirements for bilingual students are limited. This thesis seeks to bridge this gap by presenting findings for History, Geography, Biology, and Mathematics, allowing for a comprehensive understanding of language demands. This research endeavors to enrich the field of bilingual education and CLIL, ultimately benefiting the academic success of students in an interconnected world.
The trends of industry 4.0 and the further enhancements toward an ever changing factory lead to more mobility and flexibility on the factory floor. With that higher need of mobility and flexibility the requirements on wireless communication rise. A key requirement in that setting is the demand for wireless Ultra-Reliability and Low Latency Communication (URLLC). Example use cases therefore are cooperative Automated Guided Vehicles (AGVs) and mobile robotics in general. Working along that setting this thesis provides insights regarding the whole network stack. Thereby, the focus is always on industrial applications. Starting on the physical layer, extensive measurements from 2 GHz to 6 GHz on the factory floor are performed. The raw data is published and analyzed. Based on that data an improved Saleh-Valenzuela (SV) model is provided. As ad-hoc networks are highly depended onnode mobility, the mobility of AGVs is modeled. Additionally, Nodal Encounter Patterns (NEPs) are recorded and analyzed. A method to record NEP is illustrated. The performance by means of latency and reliability are key parameters from an application perspective. Thus, measurements of those two parameters in factory environments are performed using Wireless Local Area Network (WLAN) (IEEE 802.11n), private Long Term Evolution (pLTE) and 5G. This showed auto-correlated latency values. Hence, a method to construct confidence intervals based on auto-correlated data containing rare events is developed. Subsequently, four performance improvements for wireless networks on the factory floor are proposed. Of those optimization three cover ad-hoc networks, two deal with safety relevant communication, one orchestrates the usage of two orthogonal networks and lastly one optimizes the usage of information within cellular networks.
Finally, this thesis is concluded by an outlook toward open research questions. This includes open questions remaining in the context of industry 4.0 and further the ones around 6G. Along the research topics of 6G the two most relevant topics concern the ideas of a network of networks and overcoming best-effort IP.
Organic binder mixtures and process additives have been used in refractory materials for a long time due to their property-improving effect. Coal tar pitches in particular can contain thousands of chemical compounds, of which especially polycyclic aromatic hydrocarbons (PAHs) are known to be carcinogenic and mutagenic and thus pose a risk to both the environment and human health. However, despite intensive research, the exact structure of these carbon mixtures is still not fully clarified. This is becoming an increasing problem, especially with regard to more stringent legal requirements arising from REACH, the European Chemicals Regulation for the Registration, Evaluation, Authorization and Restriction of Chemicals. Furthermore, the knowledge of the structural and chemical composition is also of great importance for optimal processing of the carbon mixtures to high-quality technical products. In the present work, an analytical strategy for the investigation of complex carbon mixtures containing PAHs is developed. Due to their complexity, a combination of different methods is used, including elemental analysis, solvent extraction, thermogravimetry, differential thermal analysis, raman and infrared spectroscopy as well as high-resolution mass spectrometry. In addition, a procedure for the evaluation of mass spectrometric data based on multivariate statistical methods such as hierarchical cluster analysis and principal component analysis is developed. The application of the developed analytical strategy to various industrially used carbon-based binder mixtures allowed the elucidation of characteristic properties, including aromaticity, molecular mass distribution, degree of alkylation and elemental composition. It was also shown that combining high-resolution time-of-flight mass spectrometry with multivariate statistical data analysis is a fast and effective tool for the classification of complex binder mixtures and the identification of characteristic molecular structures. In addition, the analytical strategy was applied to manufactured refractory products. Despite the small amount of the contained organic phase, characteristic structural features of each sample could be identified and extracted, which enabled an unambiguous classification of the refractory products.
Die Geometrie unseres Anschauungsraumes – die euklidische Geometrie – ist für einen allgemeinbildenden Mathematikunterricht elementar. Seitens der Mathematiklehrkraft stellt grundsätzlich ihr Fachwissen das Fundament des Unterrichtens dar. Als Teil ihres Professionswissens sollten Mathematiklehrkräfte prinzipiell über ein Fachwissen verfügen, das in Bezug zur akademischen Mathematik den unterrichtlichen Anforderungen der schulischen Mathematik gerecht wird.
Die im Rahmen der Dissertation entwickelte Theorie des metrisch-normalen euklidischen Raumes charakterisiert sich in ihrer perspektivischen Dualität, der mathematischen Stringenz eines axiomatisch-deduktiven Vorgehens auf der einen und der Berücksichtigung der fachdidaktischen Anforderungen an Mathematiklehrkräfte auf der anderen Seite; sie hebt sich darin von bestehenden Theorien ab.
With the increasing importance and urgency of climate change, companies are challenged to contribute to sustainable development, especially by younger generations. However, existing corporate contributions have been criticized as insufficient, which could be particularly caused by a lack of employee engagement in corporate sustainability. In this context, gamification has been proposed and increasingly investigated in recent years as a promising, innovative tool to motivate sustainable employee behaviors in the workplace. However, there are few studies and applicable gamification solutions that address more than one specific sustainability issue and thus take a holistic perspective on sustainable behaviors in the workplace. Moreover, previous research lacks a comprehensive understanding of how different gamification elements elicit specific psychological effects, how these manifest in behavioral changes, and how these, in turn, cumulatively result in measurable corporate outcomes. The path from gamification as ”input” to corporate sustainability as ”output” thus remains unexplored.
This dissertation fills this gap by conceptualizing, designing, and evaluating a holistic gamified intervention that supports employees in various sustainable behaviors in their daily activities. The project uses a design science research approach that closely involves employees in the incremental development of the solution. As part of the iterative design process, this dissertation presents six studies to extend the theoretical understanding of gamification for sustainable employee behaviors. First, a comprehensive review of existing research on gamification for sustainable employee behavior is provided, analyzing gamification designs and results of previous studies and outlining an agenda for further research (Study 1). Theoretical foundations of research on gamification, serious games, and game-based learning (Study 2) and empirical design principles for gamification and persuasive systems (Study 3) are then systematically reviewed as a basis for the successful design of gamified applications. Subsequently, empirical studies explore employees’ motivations for sustainable behavior and illuminate their expectations for design features (Study 4), and identify contextual challenges and design dilemmas when implementing gamification in an organizational context (Study 5). Finally, a quantitative field study (Study 6) explores how different gamification designs influence sustainable employee behavior and corporate sustainability in organizations. Based on the findings, this dissertation presents a comprehensive framework of gamification for sustainable employee behavior that incorporates design, individual behavior, and organizational perspectives. Finally, building on these insights, it provides practical recommendations for designing gamification to encourage sustainable employee behavior at work.
Bauxite is, among other raw materials, an important material for the production of refractories. However, the availability of refractory raw material grades is limited worldwide. As high iron contents have a negative influence on the temperature resistance of the refractory material produced, a maximum iron oxide content of 2 wt.-% in the bauxite is acceptable. This means that only native raw materials from a few deposits can be used. In order to counteract the problem of too high iron oxide contents in natural bauxites, the possibility of processing bauxite for the refractory industry by using an acid leaching process was to be investigated within the scope of this work. In previous studies on this topic, some investigations on iron leaching have already been carried out on individual bauxites. However, the resulting bauxite composition was mostly neglected in its entirety and only the influences of individual leaching parameters on the leaching result were investigated independently. Moreover, the results and procedures generated are not generally valid and cannot be transferred to bauxites of other chemical or mineralogical compositions.
In order to clarify the open questions in the processing of natural bauxites, leaching tests with hydrochloric acid were carried out on five different bauxites within this work. By using computerized statistical design of experiments, an individual model was generated for each bauxite to predict the optimal factor settings. The factors investigated were acid concentration, solid-acid ratio, leaching temperature, leaching time and grain fraction. The general planning method for bauxite processing developed in this context contains all necessary factors, useful factor settings and the effects to be considered during planning and evaluation. It could be shown that, based on this planning method, a significant, individual model can be created for each of the bauxites investigated, which predicts the optimal leaching settings for the corresponding bauxite. Furthermore, it was found that the transfer of an already created model to another bauxite of similar composition is possible. Based on the results obtained from the leaching tests and model fittings, in combination with further results on the structural analysis of the bauxites, insights into the leachability of various aluminium and iron minerals from bauxite could be gained.
To develop a sustainable acid leaching process, the possibility of regenerating the contaminated acid produced was also tested as an example. It was shown that liquid-liquid extraction can extract more than 99 % of the iron present in the solution and that the regenerated acid can then be reused for the leaching process.
Wie hingen Sprache und Gewalt im Nationalsozialismus zusammen? Ausgehend von der konstitutiven Sprachphilosophie des kanadischen Philosophen Charles Taylor untersucht die Dissertation die destruktive Wirkmacht der Sprache am Fall des Nationalsozialismus, der auf ungekannte Weise in die Sprache eingriff und damit Gewalt begünstigte, die bis heute ohnegleichen ist.
Im Rahmen des vorliegenden Promotionsprojekts wird untersucht, welche Körperideologien in den drei unterschiedlichen Sportfeldern Hochleistungs-, Gesundheits- sowie Erlebnis- bzw. Funsport gegeben sind und welchen gesellschaftswirksamen Einfluss diese Ideologien aufweisen. Im Rahmen der zentralen Forschungsfrage wird des Weiteren erforscht, welche diskursiven Mittel bei Körperideologien im Sportbereich eingesetzt werden, welche Formationen in Bezug auf den Gegenstand, welche Äußerungsmodalitäten, Begrifflichkeiten und Strategien dem Diskurs zugrundeliegen und wer als TrägerIn oder AdressatIn des Diskurses identifiziert werden kann. Außerdem steht die Fragestellung im Fokus, welche Bezüge zu anderen Diskursen bestehen und um welche Diskurse es sich dabei handelt. Körperideologien des Sports werden in diesem Zusammenhang als Vorstellungen von einem (idealen) Körper betrachtet, welche durch den Sport übertragen und in der Gesellschaft verbreitet werden. Dabei wird zunächst der Begriff der Ideologie theoretisch hergeleitet und definiert sowie im Hinblick auf die vorliegende Arbeit als Weltdeutung mit einem Anspruch auf Alleinvertretung aufgefasst. Des Weiteren wird die Gouvernementalitätstheorie von Foucault aufgegriffen und für die Identifizierung der Macht- und Herrschaftsstrukturen in Bezug auf die untersuchten Körperideologien herangezogen. Dabei geht es darum, inwieweit die durch den Sport übermittelten Körperideologien dazu geeignet sind, in einem gouvernementalitätstheoretischen Sinne Führung zur Selbstführung zu ermöglichen. In einer sportsoziologischen Hinsicht beinhaltet der Sport leistungsbezogene Eigenschaften, welche in auf Effektivität abzielenden wirtschaftlichen Prozessen eine grundlegende Voraussetzung darstellen. Im Rahmen der Studie werden für jeden der drei genannten Sportbereiche jeweils zwei Individualsportarten ausgewählt, bei welchen die fokussierten Körperideologien untersucht werden. Während im Bereich des Hochleistungssports Schwimmen und Biathlon und im Bereich des Gesundheitssports Nordic Walking sowie Pilates betrachtet werden, stellen Stand Up Paddling und Parkour die fokussierten Sportarten im Bereich des Fun- bzw. Erlebnissports dar. Für die vorliegende Untersuchung kommt das Verfahren der kritischen Diskursanalyse (KDA) von Jäger zur Anwendung, da dieses für die Rekonstruktion von ideologischen Diskursen geeignet erscheint. Hierfür werden aus den drei Sportbereichen sowohl Print- als auch Onlinepublikationen sondiert und anhand von Strukturanalysen hinsichtlich verschiedener formaler und inhaltlicher Charakteristika untersucht. Des Weiteren wird mit Hilfe der tiefergehenden Feinanalyse jeweils ein Artikel pro Sportart explorativ analysiert, um verschiedene Muster zu vorhandenen Körperideologien in den fokussierten Sportarten und Sportbereichen identifizieren und anhand ausgewählter Textstellen belegen zu können. Bei den Ergebnissen zeigt sich, dass der Körper in den Hochleistungssportarten Schwimmen und Biathlon als formbares Material bzw. als Instrument zur Erbringung sportlicher Höchstleistungen betrachtet und dargestellt wird. Auch im Gesundheitssport wird der Körper als form- bzw. trainierbar hervorgehoben, wobei hierbei die Gesundheit im Fokus steht und mit Schlankheit gleichgesetzt wird. Im Bereich des Fun- bzw. Erlebnissports zeigt sich bei der Sportart Stand Up Paddling der Körper ebenfalls als zu bearbeitendes Objekt. Dagegen wird bei der Sportart Parkour der angenommene Normalismus von Jugendlichkeit anhand der Ergebnisse widerlegt. Deutlich wird, dass als diskursives Mittel vor allem der Körper als formbares Material erscheint. Dabei stehen in Bezug auf die Äußerungsmodalitäten und Begrifflichkeiten der Diskurse vor allem das Leistungsmaximum, aber auch Schlankheit und Fitness im Fokus. Die identifizierten Diskurse sind an die gesamte Gesellschaft adressiert und werden zudem durch sich selbst getragen, wodurch sie nicht nur die Realität abbilden, sondern auch ein Eigenleben in der Form entwickeln, dass sie als Träger von Wissen fungieren.
Eltern spielen eine entscheidende Rolle bei der Inanspruchnahme von kultureller Bildung durch Kinder und Jugendliche. Häufig sind sie in die Organisation und Finanzierung der kulturellen Bildungsangebote involviert. Insbesondere in ländlichen Räumen kommt die Besonderheit hinzu, dass Eltern aufgrund größerer räumlicher Distanzen und einer unzureichenden Ausstattung des ÖPNV Begleitfahrten mit dem eigenen PKW durchführen müssen. Häufig werden ländliche Räume anhand objektivierbarer Daten als strukturschwach oder kulturarm beschrieben. Darüber, ob oder inwiefern das von ländlich lebenden Eltern ebenso gesehen wird, ist jedoch wenig bekannt.
Die vorliegende Dissertationsschrift gibt einen Einblick in die elterlichen Perspektiven auf kulturelle Bildung in ländlichen Räumen. Sie basiert auf offenen, qualitativen Leitfadeninterviews mit Eltern aus vier ländlichen Regionen Deutschlands, die diskursanalytisch und unter Zuhilfenahme von Kodierungspraktiken aus dem Kontext der Grounded Theory ausgewertet wurden.
In den Interviews zeigt sich eine Vielzahl an elterlichen Verständnissen und Positionierungsweisen zur kulturellen Bildung in ländlichen Regionen. Es stellt sich heraus, dass der elterliche Diskurs auf einem komplexen Zusammenspiel sozioökonomischer bzw. -kultureller Bedingungen, raumstruktureller Gegebenheiten und individueller Präferenzen hinsichtlich kultureller Bildung auf dem Land basiert.
Praktika als gängige Lehr-Lernformate in hochschulischen Kontexten setzen stets die Zusammenarbeit verschiedener Institutionen und Personen voraus, da Studierende mit einem Praktikum den Lernort der Universität verlassen und in einen beruflichen Handlungszusammenhang mit den zugehörigen organisationalen Strukturen versetzt werden. Praktika werden unter anderem als Elemente der Berufsorientierung gesellschaftliche Implikationen zugeschrieben. Als Format innerhalb eines hochschulischen Bildungsgangs sind sie darüber hinaus mit didaktischen Begründungen verbunden und durch die Beteiligung verschiedener Personen auch mit individuellen Interessen. Studierende sind während eines Praktikums in der Rolle als Praktikant*in in besonderer Weise individuell gefordert. Ergänzt werden diese Perspektiven durch die Betrachtung disziplinärer und professioneller Implikationen, die sich für Praktika erziehungswissenschaftlicher Studiengänge ergeben. Zusammenarbeit findet in Praktika zwischen Organisationen, in Organisationen und zwischen Personen statt. Der geringe Forschungsstand zu Perspektiven auf Fragen der Zusammenarbeit für in erziehungswissenschaftliche Studiengänge integrierte Praktika bietet den Anlass der Studie. Um die verschiedenen Perspektiven auf Praktika als Zusammenarbeit zu erheben, werden qualitative episodische Interviews sowohl mit den Studierenden und Lehrenden einer Universität, als auch mit für Praktika verantwortlichen Tätigen aus dem beruflichen Bereich durchgeführt, die nach der qualitativen inhaltlich strukturierenden Inhaltsanalyse ausgewertet werden. Aus der Auswertung der geführten Interviews mit den drei Akteur*innen-Gruppen ergibt sich ein Einblick darin, wie sich Zusammenarbeit zwischen pädagogisch tätigen Institutionen, Universitäten und Studierenden in und durch Praktika konkretisiert. Es werden beispielsweise Aspekte der Interaktionsbezogenen Dimensionen beschrieben, wie auftauchende Dilemmata, Resonanzen, Kulturen des Umgangs, Interessenslagen und Konstellationen von Akteur*innen. Diese werden ergänzt um Aspekte der Dimensionen mit Bezug zu Institutionen, Umwelt, Aufgaben und Personen. Die Interviewaussagen von drei interviewten Akteur*innen-Gruppen Studierende, Praxisanleiter*innen, universitäre Lehrende werden vergleichend anhand dieser Dimensionen betrachtet und als Ergebnisse dieser Studie dargestellt. Die Ergebnisse liefern Aussagen dazu, wie Zusammenarbeit in Praktika erziehungswissenschaftlicher Studiengänge von den beteiligten Akteur*innen-Gruppen wahrgenommen wird. Dies kann dazu beitragen die differierenden Perspektiven anschlussfähig zu machen für die didaktische und organisatorische Gestaltung von Praktika durch Institutionen wie Universitäten und Praktikumseinrichtungen, aber auch durch Initiative von Studierenden in der Rolle als Praktikant*innen während eines erziehungswissenschaftlichen Studiums. Auch für weitere Forschungsprojekte zum Zusammenwirken der Beteiligten in Praktika kann die Studie Anstöße bieten.
Antonio Lotti und seine liturgische Kirchenmusik – Vorstudien zu Biographie und Überlieferung
(2023)
Antonio Lotti (1667-1740) gehört zu den venezianischen Komponisten, die in der älteren wie der neueren Fachliteratur ein hohes Ansehen genießen, obwohl seine Werke bis heute nur wenig bekannt sind. Eine unklare Überlieferungslage, aber auch sachfremde ästhetische Postulate verzögerten jedoch die Auseinandersetzung mit Lottis Kompositionen. Erst in neuerer Zeit gab es ein verstärktes Interesse sowohl an seinen Opern und vokaler Kammermusik als auch an seiner Kirchenmusik.
In der vorliegenden Studie wird zunächst Lottis Biographie unter Einbeziehung neuer Quellenfunde auf dem aktuellen Stand des Wissens zusammenfassend dargestellt. Der zweite Teil bietet erstmals eine Identifikation von Lottis Buchstaben- und Notenschrift nach streng philologischen Kriterien. Angesichts des nicht mehr erhaltenen Nachlasses ist dieser Teil von besonderer Bedeutung, bietet er doch die unverzichtbare Basis zur weiteren Erforschung von Lottis Kirchenmusik, ihrer Überlieferung und Faktur.
In the last decade, policy-makers around the world have turned their attention toward the creative industry as the economic engine and significant driver of employments. Yet, the literature suggests that creative workers are one of the most vulnerable work-forces of today’s economy. Because of the highly deregulated and highly individuated environment, failure or success are believed to be the byproduct of individual ability and commitment, rather than a structural or collective issue. This thesis taps into the temporal, spatial, and social resolution of digital behavioural data to show that there are indeed structural and historical issues that impact individuals’ and
groups’ careers. To this end, this thesis offers a computational social science research framework that brings together the decades-long theoretical and empirical knowledge of inequality studies, and computational methods that deal with the complexity and scale of digital data. By taking music industry and science as use cases, this thesis starts off by proposing a novel gender detection method that exploits image search and face-detection methods.
By analysing the collaboration patterns and citation networks of male and female computer scientists, it sheds lights on some of the historical biases and disadvantages that women face in their scientific career. In particular, the relation of scientific success and gender-specific collaboration patterns is assessed. To elaborate further on the temporal aspect of inequalities in scientific careers, this thesis compares the degree of vertical and horizontal inequalities among the cohorts of scientists that started their career at different point in time. Furthermore, the structural inequality in music industry is assessed by analyzing the social and cultural relations that breed from live performances and musics releases. The findings hint toward the importance of community belonging at different stages of artists’ careers. This thesis also quantifies some of the underlying mechanisms and processes of inequality, such as the Matthew Effect and the Hipster Paradox, in creative careers. Finally, this thesis argues that online platforms such as Wikipedia could reflect and amplify the existing biases.
The diversity within amphibian communities in cultivated areas in Rwanda and within two selected, taxonomically challenging groups, the genera Ptychadena and Hyperolius, were investigated in this thesis. The amphibian community of an agricultural wetland near Butare in southern Rwanda comprised 15 anuran species. Rarefaction and jackknife analyses corroborated that the complete current species richness of the assemblage had been recorded, and the results of acoustic niche analysis suggested species saturation of the community. Surveys at many other Rwandan localities showed that the species recorded in Butare are widespread in cultivated and pristine wetlands. The species were readily distinguishable using morphological, bioacoustic, and molecular (DNA barcoding) features, but only eight of the 15 species could be assigned unambiguously to nominal species. The remaining represented undescribed or currently unrecognized taxa, including three species of Hyperolius, two Phrynobatrachus species, one Ptychadena species, and one species of Amietia. The diversity of the Ridged Frogs in Rwanda was investigated in two studies (Chapters III and IV). Three species of Ptychadena were recorded in wetlands in the catchment of the Nile. They can be distinguished by morphological characters (morphometrics and qualitative features) as well as by their advertisement calls and genetics. The Rwandan species of the P. mascareniensis group was shown to differ from the topotypic population as well as from other genetic lineages in sub-Saharan Africa and an old available name, P. nilotica, was resurrected from synonymy for this lineage. Two further Ptychadena species were identified among voucher specimens from Rwanda deposited in the collection of the RMCA, P. chrysogaster and P. uzungwensis. Morphologically they can be unambiguously distinguished from each other and the three other Rwandan species. A key based on qualitative morphological characters was developed, which allows unequivocal identification of specimens of all species that have been recorded from Rwanda. DNA was isolated from a Rwandan voucher specimen of P. chrysogaster, and the genetic analysis corroborated the species" distinct status.
A species of Hyperolius collected in the Nyungwe National Park was compared to all other Rwandan species of the genus and to morphologically or genetically similar species from neighbouring countries. Its distinct taxonomic status was justified by morphological, bioacoustic, and molecular evidence and it was described as a new species, H. jackie. A species of the H. nasutus group collected at agricultural sites in Rwanda was described as a new species in the course of a revision of the species of the Hyperolius nasutus group. The group was shown to consist of 15 distinct species which can be distinguished from each other genetically, bioacoustically, and morphologically.
The aerial performance, i.e. parachuting, of the Disc-fingered Reed Frog, Hyperolius discodactylus, was described. It represents a novel observation of a behaviour that has been known from a number of Southeast Asian and Neotropical frog species. Parachuting frogs, including H. discodactylus, exhibit certain morphological characteristics and, while airborne, assume a distinct posture which is best-suited for maneuvering in the air. Another study on the species addressed the validity of the taxon H. alticola which had been considered either a synonym of H. discodactylus or a distinct species. Type material of both taxa was re-examined and the status of H. alticola reassessed using morphological data from historic and new collections, call recordings, and molecular data from animals collected on recent expeditions. A northern and a southern genetic clade were identified, a divide that is weakly supported by diverging morphology of the vouchers from the respective localities. No distinction in advertisement call features could be recovered to support this split and both genetic and morphological differences between the two geographic clades are marginal and not always congruent and more likely reflect population-level variation. Therefore it was concluded that H. alticola is not a valid taxon and should be treated as a synonym of H. discodactylus.
On the recognition of human activities and the evaluation of its imitation by robotic systems
(2023)
This thesis addresses the problem of action recognition through the analysis of human motion and the benchmarking of its imitation by robotic systems.
For our action recognition related approaches, we focus on presenting approaches that generalize well across different sensor modalities. We transform multivariate signal streams from various sensors to a common image representation. The action recognition problem on sequential multivariate signal streams can then be reduced to an image classification task for which we utilize recent advances in machine learning. We demonstrate the broad applicability of our approaches formulated as a supervised classification task for action recognition, a semi-supervised classification task for one-shot action recognition, modality fusion and temporal action segmentation.
For action classification, we use an EfficientNet Convolutional Neural Network (CNN) model to classify the image representations of various data modalities. Further, we present approaches for filtering and the fusion of various modalities on a representation level. We extend the approach to be applicable for semi-supervised classification and train a metric-learning model that encodes action similarity. During training, the encoder optimizes the distances in embedding space for self-, positive- and negative-pair similarities. The resulting encoder allows estimating action similarity by calculating distances in embedding space. At training time, no action classes from the test set are used.
Graph Convolutional Network (GCN) generalized the concept of CNNs to non-Euclidean data structures and showed great success for action recognition directly operating on spatio-temporal sequences like skeleton sequences. GCNs have recently shown state-of-the-art performance for skeleton-based action recognition but are currently widely neglected as the foundation for the fusion of various sensor modalities. We propose incorporating additional modalities, like inertial measurements or RGB features, into a skeleton-graph, by proposing fusion on two different dimensionality levels. On a channel dimension, modalities are fused by introducing additional node attributes. On a spatial dimension, additional nodes are incorporated into the skeleton-graph.
Transformer models showed excellent performance in the analysis of sequential data. We formulate the temporal action segmentation task as an object detection task and use a detection transformer model on our proposed motion image representations. Experiments for our action recognition related approaches are executed on large-scale publicly available datasets. Our approaches for action recognition for various modalities, action recognition by fusion of various modalities, and one-shot action recognition demonstrate state-of-the-art results on some datasets.
Finally, we present a hybrid imitation learning benchmark. The benchmark consists of a dataset, metrics, and a simulator integration. The dataset contains RGB-D image sequences of humans performing movements and executing manipulation tasks, as well as the corresponding ground truth. The RGB-D camera is calibrated against a motion-capturing system, and the resulting sequences serve as input for imitation learning approaches. The resulting policy is then executed in the simulated environment on different robots. We propose two metrics to assess the quality of the imitation. The trajectory metric gives insights into how close the execution was to the demonstration. The effect metric describes how close the final state was reached according to the demonstration. The Simitate benchmark can improve the comparability of imitation learning approaches.
In the last decades, it became evident that the world is facing an unprecedented, human-induced global biodiversity crisis with amphibians being one of the most threatened species groups. About 41% of the amphibian species are classified as endangered by the IUCN, but even in amphibian species that are listed as "least concern", population declines can be observed on a local level. With land-use change and agrochemicals (i.e. pesticides), two of the main drivers for this amphibian decline are directly linked to intensive agriculture, which is the dominant landscape type in large parts of Europe. Thus, understanding the situation of amphibians in the agricultural landscape is crucial for conservation measures. In the present thesis, I investigated the effects of viticulture on amphibian populations around Landau in der Pfalz (Germany) in terms of habitat use, pesticide exposure, biometric traits as well as genetic and age structure. From the perspective of amphibians, land-use change means usually the destruction of habitats in agricultural landscapes, which often leads to landscape fragmentation. Thus, I followed the question if also vineyards lead to the fragmentation of the landscape and if pesticides that are frequently used in viticulture have to be considered as a factor too, so if there is a chemical landscape fragmentation. Using telemetry, I could show that common toads (Bufo bufo) can be found directly in vineyards, but that they tend to avoid them as habitat. Analysing the genetic structure of common frogs (Rana temporaria) revealed that vineyards have to be considered as a barrier for amphibians. To identify if pesticides contribute to the resulting landscape fragmentation, I conducted an arena choice experiment in the laboratory in which I found evidence for an avoidance of pesticide-contaminated soil. Such an avoidance could be one of the underlying reasons for a potential chemical landscape fragmentation. By combining telemetry data with information about pesticide applications from local wine growers, I could show that a large part of the common toads is likely to come in contact with pesticides. Further, I demonstrated that the agricultural landscape, probably due to the application of pesticides, can have negative effects on the reproduction capacity of common toads. By studying palmate newts (Lissotriton helveticus) I found that adult newts from agricultural ponds are smaller than those from forest ponds. As I did not find differences in the age structure and growth, these differences might be carry-over effects from earlier life stages. While agricultural ponds might be suitable habitats for adult palmate newts, the potential carry-over effect indicates suboptimal conditions for larvae and/or juveniles. I conclude that the best management measure for sustaining amphibians in the agricultural landscape would be a heterogeneous cultural landscape with a mosaic of different habitat patches that work without or at least a reduced amount of pesticides. Green corridors between populations and different habitats would allow migrating individuals to avoid agricultural and thus pesticide-contaminated areas. This would reduce the pesticide exposure risk of amphibians, while preventing the fragmentation of the landscape and thus the isolation of populations.
In der Biologie stellt das Zeichnen eine zentrale Arbeitstechnik dar. Viele Studien konnten auf einen positiven Effekt des Zeichnens für bestimmte Situationen hinweisen. Schülerinnen und Schüler müssen diese Technik jedoch zunächst erlernen. Hierbei können zahlreiche Schwierigkeiten auftreten, die die inhaltliche Auseinandersetzung gefährden. Jedoch wurden sowohl Schwierigkeiten im Umgang mit unterschiedlichen Repräsentationsformen als auch der Zeichenprozess bislang nur lückenhaft untersucht. Die Studie dieser Arbeit hat daher zum Ziel, (I) den Zeichenprozess auf der Ebene der Sichtstruktur zu beschreiben, (II) die manifesten Schwierigkeiten von Lernenden zu erfassen, auf die sie während der Konstruktion biologisch bedeutsamer Repräsentationsformen (Ablaufdiagramme, mikroskopische Zeichnungen) treffen, (III) und auf Grundlage der empirischen Befunde Schülertypen abzuleiten. Vor diesem Hintergrund waren 21 Schülerinnen und Schüler angehalten, jeweils ein Ablaufdiagramm auf Grundlage eines Texts und eine mikroskopische Zeichnung auf Grundlage eines Präparats zu konstruieren und dabei laut zu denken. Fragen zur Vorerfahrung sowie retrospektiv gestellte Fragen zum Vorgehen der Teilnehmenden umrahmten den videografisch dokumentierten Prozess. Die Ergebnisse zeigen, dass der Zeichenprozess mehr als zehn unterschiedliche Tätigkeiten umfassen kann, wobei die Kerntätigkeit des Zeichnens durchschnittlich nur rund ein Drittel des Prozesses ausmacht. Die Prozessstruktur zwischen Fällen variiert erheblich. Weiterhin konnten etwa 30 Schwierigkeiten bzw. Fehler identifiziert werden, die während der Konstruktion beider Repräsentationsformen auftreten. Diese können dabei sowohl einzelne als auch mehrere Tätigkeiten betreffen und zu Tätigkeitsabbrüchen führen. Schwierigkeiten stehen häufig in Verbindung mit Tätigkeiten, die außerhalb der Kerntätigkeit des Zeichnens liegen (z. B. Abgleich mit der Textgrundlage). Bezogen auf Ablaufdiagramme stellt das Verhältnis depiktional bzw. deskriptional dargestellter Textinformationen den Ausgangspunkt der Typisierung dar: Typ I: realistisch abbildend, II: alternierend abbildend und III: schriftorientiert abbildend. Für mikroskopische Zeichnungen war die Häufigkeit des Abgleichs mit dem Objekt grundlegend für die Typisierung: Typ I: oberflächlich abbildend, II: objektorientiert abbildend und III: undifferenziert detailliert abbildend. Die Studie liefert erstmals Kategoriensysteme, die es erlauben, die Prozessstruktur des Zeichnens sichtbar und zwischen Fällen vergleichbar zu machen sowie schwierigkeitsbezogenes Grundlagenwissen zur Konstruktion von Zeichnungen, basierend auf Texten und Beobachtungen. Die Übertragbarkeit der Befunde auf andere Repräsentationsformen ist an vielen Stellen denkbar. Die theoretisch fundierte Systematisierung von Schwierigkeiten kann von weiterführenden Untersuchungsansätze aufgegriffen werden und erlaubt die Verortung situationsangemessener Unterstützungsmaßnahmen.
This thesis was motivated by the need to advance the knowledge on the variability and dynamics of energy fluxes in lakes and reservoirs, as well as about the physical processes that regulate the fluxes at both the air and water side of the air-water interface.
In the first part, I re-examine how mechanical energy, resulting from its major source – the vertical wind energy flux - distributes into the various types of water motions, including turbulent flows and surface and internal waves. Although only a small fraction of the wind energy flux from the atmosphere is transferred to the water, it is crucial for physical, biogeochemical and ecological processes in lentic ecosystems. Based on extensive air- and water-side measurements collected at two small water bodies (< 10 km2), we estimated the energy fluxes and energy content in surface and in internal waves. Overall, the estimated energy fluxes and energy content agree well with results reported for larger water bodies, suggesting that the energetics driving the water motions in enclosed basins is similar, independently of the basin size. Our findings highlight the importance of the surface waves that receive the largest fraction of the wind energy flux, which strongly nonlinearly increases for wind speeds exceeding 3 m s-1. We found that the existing parameterization of the wave height as a function of wind speed and fetch length did not reproduce the measured wave amplitude in lakes. On average, the highest energy content was observed in basin-scale internal waves, together with high-frequency internal waves exhibiting seasonal variability and varies among the aquatic systems. During our analysis, we discovered the diurnal variability of the energy dissipation rates in the studied lake, suggesting biogenic turbulence generation, which appears to be a widespread phenomenon in lakes and reservoirs.
In the second part of the thesis, I addressed current knowledge gaps related to the bulk transfer coefficients (also known as the drag coefficient, the Stanton number and the Dalton number), which are of a particular importance for the bulk estimation of the surface turbulent fluxes of momentum, sensible and latent heat in the atmospheric boundary layer. Their inaccurate representation may lead to significant errors in flux estimates, affecting, for example, the weather and climate predictions or estimations of the near-surface current velocities in lake hydrodynamic models. Although the bulk transfer coefficients have been extensively studied over the past several decades (mainly in marine and large-lake environments), there has been no systematic analysis of measurements obtained at lakes of different size. A significant increase of the transfer coefficients at low wind speeds (< 3 m s-1) has been observed in several studies, but, to date, it has remained unexplained. We evaluated
the bulk transfer coefficients using flux measurements from 31 lakes and reservoirs. The estimates were generally within the range reported in previous studies for large lakes and oceans. All transfer coefficients increased substantially at low wind speeds, which was found to be associated with the presence of gusts and capillary waves (except the Dalton number). We found that the Stanton number is systematically higher than the Dalton number. This challenges the assumption made in the Bowen-ratio method, which is widely used for estimating evaporation rates from micrometeorological measurements. We found that the variability of the transfer coefficients among the lakes could be associated with lake surface area. In flux parameterizations at lake surfaces, it is recommended to consider variations in the drag coefficient and the Stanton number due to wind gustiness and capillary wave roughness while the Dalton number could be considered as constant at all wind speeds.
In the third part of the thesis, I address the key drivers of the near-surface turbulence that control the gas exchange in a large regulated river. As all inland waters, rivers are an important natural source of greenhouse gases. The effects of the widespread alteration and regulation of river flow for human demands on gas exchange is largely unknown. In particular, the near-surface turbulence in regulated rivers has been rarely measured and its drivers have not been identified. While in lakes and reservoirs, near-surface turbulence is mainly related to atmospheric forcing, in shallow rivers and streams it is generated by bottom friction of the gravity-forced flow. The studied large regulated river represents a transition between these two cases. Atmospheric forcing and gravity were the dominant drivers of the near-surface turbulence for a similar fraction of the measurement period. Based on validated scalings, we derived a simple model for estimating the relative contributions of wind and bottom friction to near-surface turbulence in lotic ecosystems with different flow depths. Large diel variability in the near-surface energy dissipation rates due to flow regulation leads to the same variability in gas exchange. This suggests that estimates of gas fluxes from rivers are biased by measurements performed predominantly during daytime.
In addition, the novelty in all the analyses described above is the use of the turbulent surface fluxes measured directly by the eddy-covariance technique – at the moment of writing, the most advanced method. Overall, this thesis is of a potential interest for a broad range of scientific disciplines, including limnology, micrometeorology and open channel hydraulics.
Inland waters play an active role in the global carbon cycle. They collect carbon from upstream landmasses and transport it downstream until it finally reaches the ocean. Along this path, manifold processing steps are evident, resulting in (permanent) retention of carbon by sediment burial as well as loss by evasion to the atmosphere. Constraining these carbon fluxes and their anthropogenic perturbation is an urgent need. In this context, attention needs to be set on a widespread feature of inland waters: their partial desiccation. This results in the emergence of formerly inundated sediments to the atmosphere, referred to as dry inland waters. One observed feature of dry inland waters are disproportional high carbon dioxide (CO2) emissions. However, this observation was so far based on local case studies and knowledge on the global prevalence and fundamental mechanisms of these emissions is lacking. Against this background, this thesis aims to provide a better understanding of the magnitude and mechanisms of carbon emissions from dry inland waters on the global and local scale and to assess the impact of dry inland waters on the global carbon cycle. The specific research questions of this thesis were: (1) How do gaseous carbon emissions from dry inland waters integrate into the global carbon cycle and into global greenhouse gas (GHG) budgets? (2) What effect do seasonal and long term drying have on the carbon cycling of inland waters? The thesis revealed that dry inland waters emit disproportional large amounts of CO 2 on a global scale and that these emissions share common drivers across ecosystems. Quantifying global reservoir drawdown and upscaling carbon fluxes to the global scale suggests that reservoirs emit more carbon than they bury, challenging the current understanding of reservoirs as net carbon sinks. On the local scale, this thesis revealed that both, heterogeneous emission pattern between different habitats and seasonal variability of carbon emissions from the drawdown area, needs to be considered. Further, this thesis showed that re-mobilization of buried carbon upon permanent desiccation of water bodies can explain the observed emission rates, supporting the hypothesis of a positive feedback-loop between climate change and desiccation of inland waters. Overall, the present thesis highlights the importance of adding emissions from dry inland waters as a pathway to the global carbon cycle of inland waters.
This study was conducted in Nyungwe National Park (NNP); a biodiversity hotspot Mountain rainforest of high conservation importance in Central Africa, but with little knowledge of its insect communities including butterflies, good indicators of climate change, and forest ecosystem health. The study aimed at availing baseline data on butterfly species diversity and distribution in NNP, for future use in monitoring climate change-driven shifts and the effects of forest fragmentation on the biodiversity of Nyungwe. Butterflies were collected seasonally using fruit-baited traps and hand nets along elevational transects spanning from 1700 m up to 2950 m of altitude. Two hundred forty-two species including 28 endemics to the Albertine Rift and 18 potential local climate change indicators were documented. Species richness and abundance declined with increasing elevation and higher seasonal occurrence was observed during the dry season. This was the first study on the spatial and temporal distribution of butterflies in NNP and further studies could be conducted to add more species and allow a depth understanding of the ecology of Nyungwe butterflies.
Genetically modified plants have been grown commercially for about 25 years. Bt plants, which contain genes from the bacterium Bacillus thuringiensis (Bt) and produce Cry proteins, are used particularly frequently. Risk assessment has long focused on the terrestrial environment. Only since the publication of Rosi-Marshall et al. in 2007 potential effects on the aquatic environment came into focus. The first part of this dissertation analyse the existing literature on lower-tier effect studies and fate studies examining the effects of GM plants on the aquatic environment. Potential effects on aquatic organisms are apparent. Some studies also demonstrate the entry of GM plant material into the aquatic environment and the leaching of toxins into the water.
The second part of the dissertation investigate the effects of Cry1Ab toxin on two species of caddisfly larvae (Chaetopterryx spec., Sericostoma spec.). Trichopterans are phylogenetically closely related to lepidopterans, which are often the target organisms of Cry toxins. In order to be able to create several concentrations, a new spiking method was used in which dissolved Cry1Ab toxin was applied on leaves of black alder (Alnus glutinosa). Effects were particularly evident at sublethal endpoints. The lipid content of Chaetopteryx spec. larvae was lower after twelve weeks with increasing Cry1Ab concentration. The reduction in lipid content may indicate an increase in energy requirements for repair mechanisms. Sericostoma spec. showed a slowdown in larval development at the highest Cry1Ab concentration after six weeks, which could lead to later emergence and thus effects on the food chain.
In the third part of the dissertation, the assessment of impacts of GM crops on the aquatic environment was investigated using higher-tier studies. Since higher-tier studies are already common with pesticides, these were compared to the higher-tier studies already conducted with GM crops. It is found that there is no standardization of higher-tier studies with GM crops, which is necessary for quality assurance and comparability of studies. In addition, there are great difficulties in establishing different test concentrations, which is necessary for the investigation of a dose-response relationship.
Overall, it is clear that there are still significant knowledge gaps of the effects of GM plants on the aquatic environment. Further studies are essential for a comprehensive and meaningful risk assessment.
Manmade dams have been constructed from centuries for multiple purposes, and in the past decades they have been constructed in a fast pace, with the hotspot in tropical and subtropical regions. However, studies that explore hydrodynamics in these areas are scarce and biased to the rich literature available for temperate regions. Lakes and reservoirs have the same controlling mechanisms for physical processes and primary production, hence, analyses that were initially conceptualized for lakes are frequently applied for reservoirs. Nevertheless, longitudinal gradients in reservoirs challenges the application of these approaches.
Degradation of water quality in reservoirs is a major concern, and it is expected to be aggravated with climate change. Therefore, studies that explore mechanisms controlling water quality are essential for the maintenance of these systems, especially in tropical and subtropical regions. The aim of this thesis is to comprehend the role of hydrodynamic processes in the fate of nutrients in reservoirs and its implications on water quality, in a subtropical region. With focus on the relevance of different density current patterns. For that, analyses combining field measurements and numerical simulations were performed in a medium to small size subtropical drinking water reservoir for a complete seasonal cycle. Measurements were conducted combining several approaches: traditional sampling, sensors in high temporal and spatial resolution, and remote sensing. Besides, hydrodynamic models were set up and calibrated to reproduce observations, and to simulate scenarios that assisted on the analysis.
Results showed that different flow paths of density currents did not influence on phytoplankton dynamics. At the regions where the main nutrient supply was the river inflow (upstream), the density currents did not vary, the euphotic zone usually covered the entire depth, and vertical mixing was observed on a daily basis, turning the flow path of the density currents irrelevant. At downstream regions, the remobilization of nutrients in the sediment was the main source for primary production. Even though density currents had a seasonal pattern in the downstream region, thermal stratification conditions were the driver for variations in chlorophyll-a concentrations, with peaks after vertical mixing. This mechanism had in its favor the frequent anoxic conditions in the hypolimnion that enhanced the dissolution of reactive phosphorus from the sediment. Anoxic conditions were easily reached because the sediment in the downstream area was rich in organic matter. Phytoplankton produced in the upstream area was transported by the density currents, and for this reason, large concentrations of chl-a was observed below the euphotic zone. Further, the extensive measurements of temperature, and flow velocities, together with the hydrodynamic models, provided insights about the hydrodynamics of reservoirs. For instance, that the relevant processes occurred along the longitudinal, and mixing conditions varied along it. The relevance of inflow conditions regarding the presence of structures such as forebays and pre-dams, and the degree of stream shading in the catchment was assessed. And turbulence and internal waves had different features than the documented for high latitudes. Those findings can assist on the management of reservoirs, based on the comprehension of the physical processes.
Der Arbeitsmarkt in Deutschland erlebt einen technologisch bedingten Strukturwandel. Durch Digitalisierung werden Tätigkeiten substituierbar, Berufsbilder und dafür benötigte Qualifikationsprofile wandeln sich. Für die Arbeitskräfte resultiert daraus ein Anpassungsdruck, sich zum Erhalt ihres Humankapitals bzw. ihrer Beschäftigungsfähigkeit weiterzubilden. Fraglich ist, inwieweit die Individuen diesen Druck wahrnehmen und mit entsprechenden Weiterbildungen reagieren. Um einen Erklärungsbeitrag zum Weiterbildungsverhalten der Arbeitskräfte in Bezug auf den technologischen Wandel zu leisten, widmet sich das Promotionsvorhaben der Forschungsfrage: „Inwieweit reagieren Arbeitskräfte bezüglich ihres Weiterbildungsverhaltens auf einen sich digitalisierungsbedingt wandelnden Arbeitsmarkt?“
This dissertation is dedicated to a new concept for capturing renunciation-oriented attitudes and beliefs — sufficiency orientation. Sufficiency originates in the interdisciplinary sustain-ability debate. In contrast to efficiency and consistency, sufficiency considers human behaviour as the cause of socio-ecological crises and strives for a reduction in consumption respecting the planetary boundaries. The present work places sufficiency in a psychological research context and explores it qualitatively and quantitatively. On the basis of five manuscripts, the overarching question pursued is to what extent sufficiency orientation contributes to socio-ecological transformation. Based on one qualitative study and five further quantitative studies, sufficiency orientation is investigated in different behavioural contexts that are of particular importance with regard to CO2 emissions. In addition, sufficiency orientation is linked to a wider range of psychologically relevant theories that help gain an overview of correlates and possible causes for the development of a sufficiency orientation.
Manuscript 1 uses expert interviews (N = 21) to develop a heuristic framework on a transformation towards societal sufficiency orientation including barriers and enablers, as well as ambiguities on such a change. The derived elements are interpreted in the light of the leverage points approach. This framework can serve as a heuristic for future research and to develop measures concerning sufficiency orientation.
As part of an online study (N = 648), Manuscript 2 examines the extent to which sufficiency orientation can be embedded in classic models for explaining pro-environmental intentions and behaviour (Theory of Planned Behaviour, Norm Activation Model), and showed a significant contribution to the explanation of intentions and behaviour in the field of plastic consumption.
Manuscript 3 reports two framing experiments (Study 1, N = 123, Study 2, N = 330) to investigate how pro-social justice sensitivity contributes to making sufficiency orientation more salient and promoting it. While sufficiency orientation and pro-social facets of justice sensitivity were positively related to each other, there was no effect of the framing intervention in the hypothesised direction. The results indicate that justice-related information at least in the presented manner is more likely to generate reactance.
Manuscript 4 presents an online study (N = 317) and targets the importance of sufficiency orientation for predicting actual greenhouse gas emissions in relation to flight behav-iour and policy support for the decarbonisation of mobility. In addition, the connection between sufficiency orientation and global identity is examined. It turns out that sufficiency orientation is superior to global identity in predicting actual emissions and decarbonisation policies. Contrary to expectations, sufficiency orientation and the form of global identity operationalised in the presented study shows a positive correlation and are compatible.
Manuscript 5 reports a reflective diary intervention (N = 252) that should lead to a short- and long-term increase in sufficiency orientation by satisfying basic psychological needs through induced self-reflection. For both groups with or without the intervention, sufficiency orientation increased slightly but significantly. Although no specific effect of the manipulation was found, basic psychological need satisfaction turns out to be the largest predictor for sufficiency orientation. Subjective well-being is positively associated with sufficiency orientation, while time affluence shows no clear associations in the study.
Overall, the results highlight the relevance of sufficiency orientation in relation to socio-ecological transformation and actual behavioural change. Sufficiency orientation is related to low-emission behaviour and support for political measures to decarbonize infrastructures. These results contribute to the discussion on the intention-behaviour gap in regard to impact-relevant behaviour, i.e. behaviour producing high emissions. The present findings suggest, that sufficiency orientation could be related to a strong intention-behavioural consistency. However, further research is needed to validate these results and improve the measurement of sufficiency orientation. Furthermore, the studies provided insights on correlates of sufficiency orientation: justice sensitivity, global identity, subjective well-being and left-wing liberal political ideologies are all found to be positively related to sufficiency orien-tation. Moreover, basic psychological need satisfaction was identified as a potential mechanism that can support the emergence of sufficiency orientation, however, causality remains unclear. From these findings, the work derives practical implications how to possibly strengthen sufficiency orientation on the micro, meso and macro levels of society.
Taken together, the dissertation provides important insights into a new and still developing concept, and shows its connectivity to psychological theories. However, future research is required in order to grasp more precisely the complexity of sufficiency orientation and to understand origins and predictors of sufficiency orientation. This work contributes to the interdisciplinary debate on socio-ecological transformation and points out that sufficiency orientation can serve to a future worth living as being related to reduced consumption.
Scientific experimentation in the special needs schools for pupils with intellectual disabilities
(2022)
Naturwissenschaftliches Experimentieren im Förderschwerpunkt geistige Entwicklung: An Schulen mit dem Förderschwerpunkt geistige Entwicklung führen Schülerinnen und Schüler nur selten naturwissenschaftliche Experimente durch. Doch auch diese Schülerschaft kann mit adressatengerechten Lernmaterialien Experimente durchführen, deren Gestaltungskriterien in dieser Studie ermittelt werden. Zudem wird in der Studie erfasst, wie sich die Schülerinnen und Schüler über ein Schuljahr in ihrer experimentellen Kompetenz weiterentwickeln.
Formen des Zugangs in der Jugendhilfe – zur Gestaltung von Zugängen zum System der Hilfen zur Erziehung Kindern, Jugendlichen und Erwachsenen in unterschiedlichen familiären Beziehungen und Lebenslagen stehen in Deutschland bei Bedarf und auf Wunsch öffentliche Hilfeleistungen rund um das Thema Erziehung zur Verfügung. Repräsentiert wird dieses Angebot als Rechtsanspruch öffentlicher Hilfe in der Regel durch die örtlichen Jugendämter. In Folge der Einführung des Sozialgesetzbuches VIII (Kinder- und Jugendhilfegesetz, jetzt: Kinder- und Jugendstärkungsgesetzt/KJSG) befassten sich wiederholt wissenschaftliche Erhebungen mit dem Nutzen und den Wirkungen der in den Hilfen zur Erziehung vorhandenen Angebote aus Sicht der Adressatinnen und Adressaten, also den Kindern, Jugendlichen und Eltern. Dem Rechtsanspruch mit dem Angebot auf die Hilfen zur Erziehung auf der einen Seite, stehen die Adressatinnen und Adressaten dieser Hilfen auf der anderen zunächst gegenüber. Im Fokus der damit einhergehenden Adressaten- und Adressatinnenforschung steht die Frage, wie Adressatinnen und Adressaten den Zugang zu diesen Hilfen in ihrem Alltagsleben erhalten und ggf. integrieren. Ziel dieser Arbeit ist es daher zu untersuchen, wie sich aus Sicht von Eltern mit Jugendhilfeerfahrung dieser Zugang gestaltet, wie sie ihre diesbezüglichen Erfahrungen einordnen und bewerten. Um sich die Lebenswelten und Sinnhorizonte der Eltern zu erschließen, erfolgte die Datenerhebung durch transkribierte narrative Interviews. Diese wurden mittels qualitativ inhaltsanalytischer Verfahren strukturiert und sequenziert untersucht, um relevante Kodes, Konzepte und Kategorien aus den Erzählungen herauszuarbeiten. Dabei stellte sich heraus, dass es den einen Zugang nicht gibt, im Weiteren auch kein einfaches Setting zwischen Angebot und Nachfrage vorliegt. Vielmehr zeigen sich unterschiedliche Zugangsformen und individuelle Faktoren, die einen Zugang begünstigen oder behindern können. Zentral sind hier vor allem die Wirkung Anderer in der Biografie der Eltern, gleich ob aus Familie oder auf Seiten der Fachkräfte sowie deren Haltungen und das Vorhandensein von Ressourcen wie z.B. Wissen. Für die Praxis der Sozialen Arbeit bedeutet dies, sich den zunächst fremden Lebenswelten
der Adressatinnen und Adressaten verstehend zu nähern und nicht außer Acht zu lassen, dass diese ihnen mit ihren Bildern, Ideen, Wünschen und Lebenserfahrungen gegenüber treten, welche wahrgenommen und verstanden werden wollen.
Ralf Schauf
Die Ukraine sieht seit dem Euromaidan im Jahr 2014 ihre Zukunft in einer stabilen Veran-kerung im westlichen Wertesystem. Für die EU ist die Ukraine ein priority partner und damit von besonderem Gewicht. Deshalb lag es folgerichtig im Interesse der EU, die Ukra-ine nach Kräften auf diesem Weg zu unterstützen.
Die wissenschaftliche Forschung zur EU-Demokratieförderung konzentrierte sich bis-her im Wesentlichen auf Staaten mit konkreter EU-Beitrittsperspektive. Sie kam zu dem Ergebnis, dass der Erfolg der Demokratieförderung maßgeblich von der Konditionierung eines EU-Beitritts getragen war. Damit konnte dieser Erfolg der EU als dominanter Träger der Demokratieförderung zugeordnet werden.
Mit dem Fokus auf Staaten ohne EU-Beitrittsperspektive entfällt diese Konditionie-rung. Auch weitere Akteure traten bei der Demokratieförderung hinzu, und die Wirksam-keit der Demokratieförderung kann nicht mehr der EU direkt zugeordnet werden. Es ent-stand also eine Forschungslücke, in welcher Weise jetzt die Wirksamkeit der EU-Demokratieförderung analysiert werden kann. Die vorliegende Studie greift diese For-schungslücke auf.
Zunächst wird analysiert, welcher Demokratiestatus der Ukraine und welche Defizite sich für den Untersuchungszeitraum ermitteln lassen. Im Anschluss erfolgt die Analyse der EU-Demokratieförderung auf der Grundlage einer eigens dafür entworfenen Definition von kohärenter Strategie, die eine statische und eine dynamische Dimension abbildet.
Die statische Dimension geht der Frage nach, ob die Zielsetzungen und Vorhaben der EU-Demokratieförderung auf die Demokratiedefizite zugeschnitten waren. Die dynami-sche Dimension des Transformationsprozesses beschäftigt sich mit der Frage, ob das jewei-lige Vorgehen den Prinzipien aus sozialkonstruktivistischer Perspektive folgte. Mit dieser sozialkonstruktivistischen Perspektive wird ein Weg aufgezeigt, wie man ohne eine EU-Beitritts-Konditionierung die Transformation demokratischer Werte und Normen erfolg-reich ausgestalten kann.
Das Ergebnis ist, dass die EU-Strategie der Demokratieförderung zwar mit ihren Ziel-setzungen und Vorhaben auf die Demokratiedefizite der Ukraine ausgerichtet war, aber auch, dass das Vorgehen in einem Fall nicht den Prinzipien aus sozialkonstruktivistischer Perspektive entsprach. Diesem Vorgehen lag keine kohärente EU-Strategie zugrunde.
Die Analyse auf der Ebene der Strategie lässt der EU-Demokratieförderung keine di-rekte Wirkung zuweisen, da auch andere Akteure eine Wirkung entfalten. Auf der Ebene eines konkreten Reformprojekts konnte dann der Nachweis geführt werden, dass die De-zen-tralisierungsreform direkt der EU zugeordnet werden kann, das Vorgehen den Prinzi-pien aus sozialkonstruktivistischer Perspektive folgt und eine positive Wirkung entfaltet.
Begünstigt wurde dieser Erfolg, da er sich auf demokratische Werte und Normen ab-stützen konnte, die in überdurchschnittlicher Ausprägung bereits vorhanden waren. Dar-über hinaus wurde aufgezeigt, dass dieses Projekt eine breit gefächerte potenzielle Wirkung auf den Reformprozess in Richtung Demokratie entfaltet.
Die Dissertation wurde am 14. Dezember 2021 abgeschlossen und an der Universität Koblenz-Landau eingereicht. Im Nachgang bietet ein „Postskript“ mit Datum September 2022 unter Berücksichtigung aktueller Entwicklungen eine Perspektive für weiterführende Forschungsfragen.
The decline of biodiversity can be observed worldwide and its consequences are alarming. It is therefore crucial that nature must be protected and, where possible, restored. A wide variety of different project options are possible. Yet in the context of limited availability of resources, the selection of the most efficient measures is increasingly important. For this purpose, there is still a lack of information. This pertains, as outlined in the next paragraph, in particular, to information at different scales of projects.
Firstly, there is a lack of information on the concrete added value of biodiversity protection projects. Secondly, there is a lack of information on the actual impacts of such projects and on the costs and benefits associated with a project. Finally, there is a lack of information on the links between the design of a project, the associated framework conditions and the perception of specific impacts. This paper addresses this knowledge gap by providing more information on the three scales by means of three empirical studies on three different biodiversity protection projects in order to help optimize future projects.
The first study “Assessing the trade-offs in more nature-friendly mosquito control in the Upper Rhine region” examines the added value of a more nature-friendly mosquito control in the Upper Rhine Valley of Germany using a contingent valuation method. Recent studies show that the widely used biocide Bti, which is used as the main mosquito control agent in many parts of the world, has more negative effects on nature than previously expected. However, it is not yet clear whether the population supports a more nature-friendly mosquito control, as such an adaptation could potentially lead to higher nuisance. This study attempts to answer this question by assessing the willingness to pay for an adapted mosquito control strategy that reduces the use of Bti, while maintaining nuisance protection within settlements. The results show that the majority of the surveyed population attaches a high value to a more nature-friendly mosquito control and is willing to accept a higher nuisance outside of the villages.
The second study “Inner city river restoration projects: the role of project components for acceptance” examines the acceptance of a river restoration project in Rhineland-Palatinate, Germany. Despite much effort, many rivers worldwide are still in poor condition. Therefore, a rapid implementation of river restoration projects is of great importance. In this context, acceptance by society plays a fundamental role, however, the factors determining such acceptance are still poorly understood. In particular, the complex interplay between the acceptance or rejection of specific project components and the acceptance of the overall project require further exploration. This study addresses this knowledge gap by assessing the acceptance of the project, its various ecological and social components, and the perception of real and fictitious costs as well as the benefits of the components. Our findings demonstrate that while acceptance of the overall project is generally rather high, many respondents reject one or more of the project's components. Complementary social project components, like a playground, find less support than purely ecological components. Overall, our research shows that complementary components may increase or decrease acceptance of the overall project. We, furthermore, found that differences in the acceptance of the individual components depend on individual concerns, such as perceived flood risk, construction costs, expected noise and littering as well as the quality of communication, attachment to the site, and the age of the respondents.
The third study “What determines preferences for semi-natural habitats in agrarian landscapes? A choice-modelling approach across two countries using attributes characterizing vegetation” investigates people's aesthetic preferences for semi-natural habitats in agricultural landscapes. The EU-Common Agricultural Policy promotes the introduction of woody and grassy semi-natural habitats (SNH) in agricultural landscapes. While the benefits of these structures in terms of regulating ecosystem services are already well understood, the effects of SNH on visual landscape quality is still not clear. This study investigates the factors determining people’s visual preferences in the context of grassy and woody SNH elements in Swiss and Hungarian landscapes using picture-based choice experiments. The results suggest that respondents’ choices strongly depend on specific vegetation characteristics that appear and disappear over the year. In particular, flowers as a source of colours and green vegetation as well as ordered structure and the proportion of uncovered soil in the picture play an important role regarding respondents’ aesthetic perceptions of the pictures.
The three empirical studies can help to make future projects in the study areas of biodiversity protection more efficient. While this thesis highlights the importance of exploring biodiversity protection projects at different scales, further analyses of the different scales of biodiversity protection projects are needed to provide a sound basis to develop guidance on identifying the most efficient biodiversity protection projects.
Instructor feedback on written assignments is one of the most important elements in the writing process, especially for students writing in English as a foreign language. However, students are often critical of both the amount and quality of the feedback they receive. In order to better understand what makes feedback effective, this study explored the nature of students’ assessments of the educational alliance, and how their receptivity to, perceptions of, and decisions about using their instructors’ feedback differed depending on how strong they believed the educational alliance to be. This exploratory case study found that students not only assessed the quality of the educational alliance based on goal compatibility, task relevance, and teacher effectiveness, but that there was also a reciprocal relationship between these elements. Furthermore, students’ perceptions of the educational alliance directly influenced how they perceived the feedback, which made the instructor’s choice of feedback method largely irrelevant. Stronger educational alliances resulted in higher instances of critical engagement, intrinsic motivation, and feelings of self-efficacy. The multidirectional influence of goal, task, and bond mean that instructors who want to maximize their feedback efforts need to attend to all three.
Social networks are ubiquitous structures that we generate and enrich every-day while connecting with people through social media platforms, emails, and any other type of interaction. While these structures are intangible to us, they carry important information. For instance, the political leaning of our friends can be a proxy to identify our own political preferences. Similarly, the credit score of our friends can be decisive in the approval or rejection of our own loans. This explanatory power is being leveraged in public policy, business decision-making and scientific research because it helps machine learning techniques to make accurate predictions. However, these generalizations often benefit the majority of people who shape the general structure of the network, and put in disadvantage under-represented groups by limiting their resources and opportunities. Therefore it is crucial to first understand how social networks form to then verify to what extent their mechanisms of edge formation contribute to reinforce social inequalities in machine learning algorithms.
To this end, in the first part of this thesis, I propose HopRank and Janus two methods to characterize the mechanisms of edge formation in real-world undirected social networks. HopRank is a model of information foraging on networks. Its key component is a biased random walker based on transition probabilities between k-hop neighborhoods. Janus is a Bayesian framework that allows to identify and rank plausible hypotheses of edge formation in cases where nodes possess additional information. In the second part of this thesis, I investigate the implications of these mechanisms - that explain edge formation in social networks - on machine learning. Specifically, I study the influence of homophily, preferential attachment, edge density, fraction of inorities, and the directionality of links on both performance and bias of collective classification, and on the visibility of minorities in top-k ranks. My findings demonstrate a strong correlation between network structure and machine learning outcomes. This suggests that systematic discrimination against certain people can be: (i) anticipated by the type of network, and (ii) mitigated by connecting strategically in the network.
Fungicide effects on the structure and functioning of leaf-associated aquatic fungal communities
(2022)
Aquatic hyphomycetes are a polyphyletic group of saprotrophic fungi growing abundantly on submerged leaf litter. In stream ecosystems shaped by allochthonous leaf litter inputs, they play a central functional role as decomposers and food source for other organisms. Fungicides pose a threat to aquatic hyphomycetes and their functions, since these substances are inherently toxic to fungi and contaminate surface waters around the world due to their widespread use in agricultural and urban landscapes. While fungicides’ potential to reduce fungal diversity are discerned, the extent of impacts on biodiversity-ecosystem functioning relationships (B EF) remains unclear. This is partly attributed to methodological constraints in the detection and quantification of single aquatic hyphomycete species within microbial leaf-associated communities. The primary aim of this thesis was, therefore, (1) to assess the ecotoxicological impacts of fungicides on B-EF relationships in aquatic hyphomycete communities. To facilitate this, subordinate aims were to (2) develop DNA-based biomolecular tools (i.e., qPCR assays) to detect and to quantify the biomass of different aquatic hyphomycete species in mixed cultures and (3) to investigate the mechanisms underlying B-EF relationships in the absence of chemical stressors.
In the course of this thesis, qPCR assays were developed for detection and species-specific biomass quantification of ten common aquatic hyphomycete species and successfully validated for application in eco( toxico )logical microcosm experiments. Via a systematic manipulation of fungal diversity, these assays allow the examination of B-EF relationships by assessments of deviations between observed and (monoculture-based) predicted activities in fungal mixed cultures. Taking advantage of these tools in a microcosm experiment, it was uncovered that leaf decomposition results from the additive activity of community members, even though functionally distinct species were present. Colonization dynamics are characterized by complex interactions. Colonization success of aquatic hyphomycetes is higher if co-occurring species are genetically and functionally distinct (i.e., complementary interactions). However, the co-occurrence of aquatic hyphomycete species does not necessarily result in a greater colonization success compared to monocultures, unless bacteria are present. Accordingly, the presence of other microbial groups such as bacteria may induce new fungal diversity-based feedback loops, which ultimately enable coexistence of aquatic hyphomycete species in the environment. Exposure to fungicides revealed substantial differences in sensitivities among aquatic hyphomycetes. The most productive species were able to cope with extremely high fungicide concentrations up to the mg/L-range. In assemblages containing these species, leaf decomposition was maintained under fungicide exposure. Yet, already at environmentally relevant fungicide concentrations, tolerant species displaced more sensitive ones, potentially affecting leaves’ nutritional quality for consumers. This thesis thus indicates that fungicide exposure poses a risk to stream food webs rather than the microbial leaf decomposition process per se.
Semantic Web technologies have been recognized to be key for the integration of distributed and heterogeneous data sources on the Web, as they provide means to define typed links between resources in a dynamic manner and following the principles of dataspaces. The widespread adoption of these technologies in the last years led to a large volume and variety of data sets published as machine-readable RDF data, that once linked constitute the so-called Web of Data. Given the large scale of the data, these links are typically generated by computational methods that given a set of RDF data sets, analyze their content and identify the entities and schema elements that should be connected via the links. Analogously to any other kind of data, in order to be truly useful and ready to be consumed, links need to comply with the criteria of high quality data (e.g., syntactically and semantically accurate, consistent, up-to-date). Despite the progress in the field of machine learning, human intelligence is still essential in the quest for high quality links: humans can train algorithms by labeling reference examples, validate the output of algorithms to verify their performance on a data set basis, as well as augment the resulting set of links. Humans —especially expert humans, however, have limited availability. Hence, extending data quality management processes from data owners/publishers to a broader audience can significantly improve the data quality management life cycle.
Recent advances in human computation and peer-production technologies opened new avenues for human-machine data management techniques, allowing to involve non-experts in certain tasks and providing methods for cooperative approaches. The research work presented in this thesis takes advantage of such technologies and investigates human-machine methods that aim at facilitating link quality management in the Semantic Web. Firstly, and focusing on the dimension of link accuracy, a method for crowdsourcing ontology alignment is presented. This method, also applicable to entities, is implemented as a complement to automatic ontology alignment algorithms. Secondly, novel measures for the dimension of information gain facilitated by the links are introduced. These entropy-centric measures provide data managers with information about the extent the entities in the linked data set gain information in terms of entity description, connectivity and schema heterogeneity. Thirdly, taking Wikidata —the most successful case of a linked data set curated, linked and maintained by a community of humans and bots— as a case study, we apply descriptive and predictive data mining techniques to study participation inequality and user attrition. Our findings and method can help community managers make decisions on when/how to intervene with user retention plans. Lastly, an ontology to model the history of crowd contributions across marketplaces is presented. While the field of human-machine data management poses complex social and technical challenges, the work in this thesis aims to contribute to the development of this still emerging field.
Currently, there are a variety of digital tools in the humanities, such
as annotation, visualization, or analysis software, which support researchers in their work and offer them new opportunities to address different research questions. However, the use of these tools falls far
short of expectations. In this thesis, twelve improvement measures are
developed within the framework of a design science theory to counteract the lack of usage acceptance. By implementing the developed design science theory, software developers can increase the acceptance of their digital tools in the humanities context.
The presented study was motivated by the dynamic phenomena observed in basic catalytic surface reactions, especially by bi- and tristability, and the interactions between these stable states. In this regard, three reaction-diffusion models were developed and examined using bifurcation theory and numerical simulations.
A first model was designed to extend the bistable CO oxidation on Ir(111) to include hydrogen and its oxidation. The differential equation system was analyzed within the framework of bifurcation theory, revealing three branches of stable solutions.
One state is characterized by high formation rates (upper rate state, UR), while the other two branches display low formation rates (lower rate (LR) \& very low rate (VLR) states).
The overlapping branches form the shape of a `swallowtail', the curve of saddle-node bifurcations forming two cusps. Increasing the temperature leads to a subsequent unfolding and hence decreases the system complexity.
A series of numerical simulations representing possible experiments was conducted to illustrate the experimental accessibility (or the lack) of said states. Relaxation experiments show partially long decay times. Quasistatic scanning illustrates the existence of all three states within the tristable regime and their respective conversion once crossing a fold.
A first attempt regarding the state dominance in reaction-diffusion fronts was done. While UR seems to dominate in 1D, a 2D time-evolution shows that LR invades the interphase between UR and VLR.
Subsequently, a generic monospecies mock model was used for the comprehensive study of reaction-diffusion fronts. A quintic polynomial as reaction term was chosen, derived by the sixth-order potential associated with the `butterfly bifurcation'. This ensures up to three stable solutions($u_{0}$,$u_{1}$,$u_{2}$), depending on the four-dimensional parameter space.
The model was explored extensively, identifying regions with similar behaviors.
A term for the front velocity connecting two stable states was derived, depending only on the relative difference of the states' potential wells.
Equipotential curves were found, where the front velocity vanishes of a given front. Numerical simulations on a two-dimensional, finite disk using a triangulated mesh supported these findings.
Additionally, the front-splitting instability was observed for certain parameters. The front solution $u_{02}$ becomes unstable and divides into $u_{01}$ and $u_{12}$, exhibiting different front velocities. A good estimate for the limit of the front splitting region was given and tested using time evolutions.
Finally, the established mock model was modified from continuous to discrete space, utilizing a simple domain in 1D and three different lattices in 2D (square, hexagonal, triangular).
For low diffusivities or large distances between coupling nodes, fronts can become pinned, if the parameters are within range of the equipotential lines. This phenomenon is known as propagation failure and its extent in parameter space was explored in 1D. In 2D, an estimate was given for remarkable front orientations respective to the lattice using a pseudo-2D approximation. Near the pinning region, front velocities differ significantly from the continuous expectation as the shape of the curve potential becomes significant. Factors that decide the size and shape of the pinning regions are the coupling strength, the lattice, the front orientation relative to the lattice, and the front itself. The bifurcation diagram shows a snaking curve in the pinning region, each alternating branch representing a stable or unstable frozen front solution. Numerical simulations supported the observations concerning propagation failure and lattice dependence.
Furthermore, the influence of front orientation on the front velocity was explored in greater detail, showing that fronts with certain lattice-dependent orientations are more or less prone to propagation failure. This leads to the possibility of pattern formation, reflecting the lattice geometry. An attempt to quantify the front movement depending on angular front orientation has shown reasonable results and good agreement with the pseudo-2D approach.
Die Studie thematisiert die Positionierung und Subjektivierung von Medienpädagog*innen im Diskurs um Gewaltdarstellungen in Computerspielen. Der sogenannte ‚Killerspiel‘-Diskurs in den Jahren 2001 bis 2016 stellt für medienpädagogische Fachkräfte ein Feld widersprüchlicher Handlungserwartungen dar, Gewaltdarstellungen in Computerspielen entweder als Problem wahrzunehmen und dieses zu bearbeiten oder Computerspiele als Chance zu begreifen. Als rele-vante Multiplikator*innen diskursiver Wissensbestände wurden deswegen für diese Studie Me-dienpädagog*innen interviewt, die an maßgeblichen Positionen in der Schnittstelle zwischen Wissenschaft und Praxis agieren und daher für viele Kolleg*innen deutungs- und praxisrelevan-tes Wissen generieren. Um die Ausrichtung dieses Wissens zu prüfen, wurde in dieser Studie die Frage gestellt, wie sich diese medienpädagogischen Fachkräfte, die korrigierend in Diskurse ein-greifen, positionieren und inwiefern (medien-)pädagogische Professionalität als Ressource und Grenze der Positionierung fungiert.
Um die Fragestellung zu beantworten wurden zwei empirisch analytische Untersuchungen durchgeführt. Zuerst wurde eine Sekundäranalyse bestehender Diskursanalysen zum ‚Killer-spiel‘-Diskurs durchgeführt, um die Subjektpositionen herauszuarbeiten, mit denen sich die Me-dienpädagog*innen auseinandersetzen mussten. In einem zweiten Schritt wurde eine qualitative Interviewstudie mit neun Medienpädagog*innen durchgeführt. Im Anschluss an die semi-narrativen Expert*inneninterviews wurden diese in einem dreistufigen Verfahren ausgewertet. Nach der deduktiven und induktiven Kategorienbildung in Anlehnung an die inhaltlich struktu-rierende Inhaltsanalyse, wurde im Rahmen einer Deutungsmusteranalyse das Deutungswissen der Medienpädagog*innen und der Sinnhorizont ihrer Intervention in den Diskurs feinanalytisch rekonstruiert. Zuletzt wurden drei biographische Fallanalysen durchgeführt, um die Relationie-rung zwischen Diskurs und (Berufs-)biographie zu diskutieren.
Im Rahmen der Sekundäranalyse des ‚Killerspiel‘-Diskurses konnte die bisher in Diskursanaly-sen rekonstruierte Differenzierung von Risiko- und Chancennarrativ erweitert werden. Durch die Abgrenzung jeweils zweier Deutungsmuster des Problemdiskurses (‚Gefahr‘ und ‚Risiko‘) und des Gegendiskurses (‚Optimierung von Lernchancen‘ und ‚Kultur‘) konnten dadurch Positionie-rungen in multiplen Konfliktfeldern sichtbar gemacht werden. So war es möglich die fachliche Positionierung der Medienpädagog*innen als Zwischenraum zu fassen, in dem sowohl Deutun-gen des Gegendiskurses als auch des Problemdiskurses eigenwillig miteinander relationiert wer-den. Die eigenwillige Aneignung diskursiver Problem- und Deutungsmuster verläuft bei den Medienpädagog*innen über unterschiedliche fachliche Schnittstellen und Kopplungen. Statt den Diskurs mit der eigenen Lebensgeschichte zu relationieren wird er mit der in Handlungsfeld-strukturen situierten fachlichen medienpädagogischen Praxis in Beziehung gesetzt. Dabei ist eine Pädagogisierung des Diskurses und eine Diskursivierung pädagogischer Handlungsfelder zu beobachten. Mittels mehrerer Pädagogiken werden diskursive Deutungsmuster transformiert und das medienpädagogische Handeln durch die Re-Interpretation medienpädagogischer Hand-lungsfelder im Sinnhorizont des Diskurses als Intervention in den Diskurs gerahmt. Gleichzeitig wird in einem ‚Opportunismus der Uneindeutigkeit‘ die Anschlussfähigkeit an Problemdeutun-gen durch die Selbstdarstellung als verantwortliche Problembearbeiter*innen gewahrt, wodurch die eigene Handlungsfähigkeit, die Legitimität des Handelns und der Zugang zu gesellschaftli-chen Ressourcen gesichert wird.
In den Fallanalysen zeigte sich, dass diese fachlichen Positionierungen nur dann einen Subjekti-vierungsprozess dokumentieren, wenn die Erzählbausteine des Diskurses (Deutungsmuster und diskursiver Konflikt) als Material für die eigene Selbsterzählung herangezogen und als Professi-onsverständnis re-artikuliert werden. Das Konfliktszenario wird dann über dessen öffentliche Thematisierung hinaus als berufsbiographisches Projekt formulierbar, was sich insbesondere da-rin zeigt, dass prospektive Zukunftsentwürfe weiterhin im Deutungs- und Konfliktspektrum des Diskurses verortet werden. Subjektivierung professioneller Akteure kann daher als über fachliche Positionierungen (als fachlich orientierte, kommentierende Auseinandersetzungen mit im Diskurs verhandelten Deutungsmustern und Wissensbeständen) hinausgehende Prozesse der Deutung des eigenen Professionalitätsverständnisses, die Ausbildung von Pädagogiken und die Veranke-rung berufsbiographischer Ziele im Horizont des Deutungsspektrum des Diskurses gefasst wer-den.
In der medienpädagogischen Professionsforschung können die Deutungsmuster und Subjektpo-sitionen des Diskurses als Professionalitätserwartungen analytisch Anwendung finden. Ihr Vor-teil gegenüber den hierfür auch herangezogenen Paradigmen der Medienpädagogik ist der Aktu-alitäts- und Gegenstandsbezug. Auch in anderen Themenbereichen (bspw. Mediensucht) können die Deutungsmuster des Diskurses sinnvoll Anwendung finden. Die Studie konnte zudem zei-gen, dass eine Subjektivierungsheuristik sinnvoll auf professionelle Akteure anwendbar ist, da fachliche Positionierungen von Subjektivierungen deutlich unterschieden werden können. Dafür wurde eine spezielle für professionelle Akteure konzipierte Subjektivierungsheuristik entworfen, die insbesondere den unterschiedlichen Funktionen diverser Wissensformen Rechnung tragen kann und in der Professionsforschung die Relevanz des diskursiven Wissens als relevanter Wis-sensform für professionelle Praxis herausstellt.
Agricultural intensification is leading to a severe decline in farmland biodiversity worldwide. The resulting landscape simplification through the expansion of monocultures and removal of non-crop habitats has a major impact on arthropod communities in agricultural landscapes. While arable fields are often highly disturbed and ephemeral habitats that are unsuitable for many species, non-crop habitats in agroecosystems can provide important refugia. The creation of non-crop habitats through agri-environmental schemes (AES) in intensive agricultural landscapes, such as the ‘Maifeld’ region in western Germany, is intended to mitigate the negative effects of agricultural intensification, although the effectiveness of these measures for nature conservation is still controversial. Therefore, this work focuses on the taxonomic and functional diversity of beetles (Coleoptera) and spiders (Araneida), being important providers of ecosystem services, between wheat fields and different non-crop habitats, namely grassy field margins adjacent to wheat and oilseed rape fields, small- and large-scale set-aside areas sown with wildflowers, and permanent grassland fallows. Arthropods were collected between 2019 and 2020 using pitfall traps and suction sampling. Land-use type influenced beetle and spider diversity in the study area, with significantly higher values in grassland fallows than wheat fields. Surprisingly, species diversity differed little among all non-crop habitats, but all harboured distinct species assemblages. In particular, large long-term grassland fallows showed the largest within-group variation of beetle and spider assemblages and represented important habitats, especially for habitat specialists and threatened species, likely due to their variable soil moisture and complex habitat structure. In contrast, the homogeneous arthropod assemblages of wheat fields exhibited lower trait richness and were dominated by a few predatory species adapted to such disturbed, man-made habitats. Interestingly, all conservation measures complemented each other in that they contributed in different ways to supporting beetles and spiders in agricultural landscapes. Even small-scale non-crop habitats and existing habitat boundaries in an agricultural matrix appear to be valuable habitats for farmland arthropods by enhancing taxonomic diversity. Field margins and small wildflower-sown patches can link isolated non-crop habitats and contribute to a heterogeneous agricultural landscape. Consequently, a combination of various small- and large-scale greening measures leads to increased compositional and configurational landscape heterogeneity, resulting in improved beetle and spider diversity. Considering the ongoing loss of farmland biodiversity worldwide, agri-environmental schemes should be promoted in the future, as they are particularly important for arthropod conservation in intensive agricultural landscapes such as the Maifeld region.
The present study deals with the synthesis of N-phenacylpyridinium salts and their use as photoinitiators for epoxy resins. The use and suitability of phenacyl salts as photoinitiators for epoxy resins has already been described in previous studies. The individual impact of the specific components on the rate constants of epoxy reaction has not been investigated in detail. Based on the structure of N-phenacylpyridinium salt the substances described in the present study were varied due to the exchange of counter ion and different substituents. Investigating the impact of the specific substituent with focus on the reaction of epoxy groups there is a dependence found for three main factors. First, depending on whether to use a phenyl or methyl group as substituent there was found an impact on the process of photolysis. Furthermore, concerning the dependences on the pyridine derivative and the counter ion, it was found that pyridine derivatives with electron withdrawing groups and counter ions, which can build strong acids, accelerate the rate constants of the epoxy reaction. Vice versa, pyridine derivatives with electron donating groups and counter ions, which can form weaker acids, decrease the rate constants.
The determined rate constants and the formulation of substances discussed in the present thesis in an adhesive formulation show the suitability of selected substances as photoinitiators for the polymerization of epoxy resins.
Diet-related effects of antimicrobials in aquatic decomposer-shredder and periphyton-grazer systems
(2022)
Leaf-associated microbial decomposers as well as periphyton serve as important food sources for detritivorous and herbivorous macroinvertebrates (shredders and grazers) in streams. Shredders and grazers, in turn, provide not only collectors with food but also serve as prey for predators. Therefore, decomposer-shredder and periphyton-grazer systems (here summarized as freshwater biofilm-consumer systems) are highly important for the energy and nutrient supply in heterotrophic and autotrophic stream food webs. However, both systems can be affected by chemical stressors, amongst which antimicrobials (e.g., antibiotics, fungicides and algaecides) are of particular concern. Antimicrobials can impair shredders and grazers not only via waterborne exposure (waterborne effect pathway) but also through dietary exposure and microorganism-mediated alterations in the food quality of their diet (dietary effect pathway). Even though the relevance of the latter pathway received more attention in recent years, little is known about the mechanisms that are responsible for the observed effects in shredders and grazers. Therefore, the first objective of this thesis was to broaden the knowledge of indirect antimicrobial effects in a model shredder and grazer via the dietary pathway. Moreover, although freshwater biofilm-consumer systems are most likely exposed to antimicrobial mixtures comprised of different stressor groups, virtually nothing is known of these mixture effects in both systems. Therefore, the second objective was to assess and predict diet-related antimicrobial mixture effects in a model freshwater biofilm-consumer system. During this thesis, positive diet-related effects of a model antibiotic on the energy processing and physiology of the shredder Gammarus fossarum were observed. They were probably triggered by shifts in the leaf-associated microbial community in favor of aquatic fungi that increased the food quality of leaves for the shredder. Contrary to that, a model fungicide induced negative effects on the energy processing of G. fossarum via the dietary pathway, which can be explained by negative impacts on the microbial decomposition efficiency leading to a reduced food quality of leaf litter for gammarids. For diet-related antimicrobial effects in periphyton-grazer systems, a model algaecide altered the periphyton community composition by increasing nutritious and palatable algae. This resulted in an enhanced consumption and physiological fitness of the grazer Physella acuta. Finally, it was shown that complex horizontal interactions among leaf-associated microorganisms are involved, making diet-related antimicrobial mixture effects in the shredder G. fossarum difficult to predict. Thus, this thesis provides new insights into indirect diet-related effects of antimicrobials on shredders and grazers as well as demonstrates uncertainties of antimicrobial mixture effect predictions for freshwater biofilm-consumer systems. Moreover, the findings in this thesis are not only informative for regulatory authorities, as indirect effects and effects of mixtures across chemical classes are not considered in the environmental risk assessment of chemical substances, but also stimulate future research to close knowledge gaps identified during this work.
Beim Zugang zur dualen Berufsausbildung haben Jugendliche und junge Erwachsene mit Migrationshintergrund schlechtere Chancen in eine betriebliche Berufsausbildung einzumünden. Vermehrt wird ein Forschungsbedarf thematisiert, der den Blick darauf richtet, wie die entsprechenden Auswahlentscheidungen in den Betrieben getroffen werden. Die Dissertation setzt an dieser Frage an und befasst sich mittels eines biographischen Zugangs mit den Personalentscheiderinnen und Personalentscheidern, den sogenannten Gatekeepern, in den Betrieben. Im Erkenntnisinteresse steht die Frage, ob und wie biographische Erfahrungen Bedeutung für Auswahlentscheidungen zugunsten zugewanderter junger Menschen haben.
To render the surface of a material capable of withstanding mechanical and electrochemical loads, and to perform well in service, the deposition of a thin film or coating is a solution. In this project, such a thin film deposition is carried out. The coating material chosen is titanium nitride (TiN) which is a ceramic material known to possess a high hardness (>10 GPa) as well as good corrosion resistance. The method of deposition selected is high power impulse magnetron sputtering (HiPIMS) that results in coatings with high quality and enhanced properties. Sputtering is a physical process that represents the removal or dislodgment of surface atoms by energetic particle bombardment. The term magnetron indicates that a magnetic field is utilized to increase the efficiency of the sputtering process. In HiPIMS, a high power is applied in pulses of low duty cycles to a cathode that is sputtered and that consists of the coating material. As result of the high power, the ionization of the sputtered material takes place giving the possibility to control these species with electric and magnetic field allowing thereby the improvement and tuning of coating properties. However, the drawback of HiPIMS is a low deposition rate.
In this project, it is demonstrated first that it is possible to deposit TiN coating using HiPIMS with an optimized deposition rate, by varying the magnetic field strength. It was found that low magnetic field strength (here 22mT) results in a deposition rate similar to that of conventional magnetron sputtering in which the average power is applied continuously, called also direct current magnetron sputtering (dcMS). The high deposition rate at low magnetic field strength was attributed to a reduction in the back attraction probability of the sputtered species. The magnetic field strength did not show noticeable influence on the mechanical properties. The proposed explanation was that the considered peak current density interval 1.22-1.72 A∙cm-2 does not exhibit dramatic changes in the plasma dynamics.
In a second part, using the optimized deposition rate, the optimized chemical composition of TiN was determined. It was shown that the chemical composition of TiN does not significantly influence the corrosion performance but impacts considerably the mechanical properties. It was also shown that the corrosion resistance of the coatings deposited using HiPIMS was higher than that of the coatings deposited using dcMS.
The third study was the effect of annealing post deposition on the properties of TiN coating deposited using HiPIMS. The hardness of the coatings showed a maximum at 400°C reaching 24.8 GPa. Above 400°C however, a lowering of the hardness was measured and was due to the oxidation of TiN which led to the formation of TiN-TiO2 composites with lower mechanical properties.
The coating microscopic properties such as crystal orientation, residual stresses, average grain size were determined from X-ray diffraction data and the roughness was measured using atomic force microscopy. These properties were found to vary with the magnetic field strength, the chemical composition as well as the annealing temperature.
The use of agricultural plastic covers has become common practice for its agronomic benefits such as improving yields and crop quality, managing harvest times better, and increasing pesticide and water use efficiency. However, plastic covers are suspected of partially breaking down into smaller debris and thereby contributing to soil pollution with microplastics. A better understanding of the sources and fate of plastic debris in terrestrial systems has so far been hindered by the lack of adequate analytical techniques for the mass-based and polymer-selective quantification of plastic debris in soil. The aim of this dissertation was thus to assess, develop, and validate thermoanalytical methods for the mass-based quantification of relevant polymers in and around agricultural fields previously covered with fleeces, perforated foils, and plastic mulches. Thermogravimetry/mass spectrometry (TGA/MS) enabled direct plastic analyses of 50 mg of soil without any sample preparation. With polyethylene terephthalate (PET) as a preliminary model, the method limit of detection (LOD) was 0.7 g kg−1. But the missing chromatographic separation complicated the quantification of polymer mixtures. Therefore, a pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) method was developed that additionally exploited the selective solubility of polymers in specific solvents prior to analysis. By dissolving polyethylene (PE), polypropylene (PP), and polystyrene (PS) in a mixture of 1,2,4-trichlorobenzene and p-xylene after density separation, up to 50 g soil became amenable to routine plastic analysis. Method LODs were 0.7–3.3 mg kg−1, and the recovery of 20 mg kg−1 PE, PP, and PS from a reference loamy sand was 86–105%. In the reference silty clay, however, poor PS recoveries, potentially induced by the additional separation step, suggested a qualitative evaluation of PS. Yet, the new solvent-based Py-GC/MS method enabled a first exploratory screening of plastic-covered soil. It revealed PE, PP, and PS contents above LOD in six of eight fields (6% of all samples). In three fields, PE levels of 3–35 mg kg−1 were associated with the use of 40 μm thin perforated foils. By contrast, 50 μm PE films were not shown to induce plastic levels above LOD. PP and PS contents of 5–19 mg kg−1 were restricted to single observations in four fields and potentially originated from littering. The results suggest that the short-term use of thicker and more durable plastic covers should be preferred to limit plastic emissions and accumulation in soil. By providing mass-based information on the distribution of the three most common plastics in agricultural soil, this work may facilitate comparisons with modeling and effect data and thus contribute to a better risk assessment and regulation of plastics. However, the fate of plastic debris in the terrestrial environment remains incompletely understood and needs to be scrutinized in future, more systematic research. This should include the study of aging processes, the interaction of plastics with other organic and inorganic compounds, and the environmental impact of biodegradable plastics and nanoplastics.
Agriculture requires a sustainable intensification to feed the growing world population without exacer-bating soil degradation and threatening soil quality. Globally, plastic mulching (PM) is increasingly used to improve crop growth and yields and consequently agronomic productivity. However, recent literature reported also critical aspects of PM for soil quality and showed contradictory outcomes. This might result from the numerous applications of PM in different climates across various crops, soils and agri-cultural techniques. Thus, a closer look is necessary on how PM influences soil processes under certain climate and cultivation conditions to obtain a comprehensive understanding of its effects, which is im-portant to evaluate PM in terms of a sustainable agriculture.
The aim of this PhD thesis was to understand how multiannual PM influences soil properties and pro-cesses under the temperate, humid Central European cultivation conditions and to evaluate the resulting consequences for soil quality. I designed a three-year field study to investigate the influence of PM (black polyethylene, 50 μm) on microclimate, structural stability, soil organic matter (SOM) and the concentrations of selected fungicides and mycotoxins in three soil layers (0–10, 10–30 and 30–60 cm) compared to straw mulching (SM). Both mulching types were applied in a drip-irrigated ridge-furrow system in strawberry cultivation.
PM shifted the soil microclimate to higher soil temperatures and lower soil moistures. The higher soil temperature seems thus to be the key factor for the increased crop growth and yields under the present humid climate. The reduced soil moisture under PM indicated that under PM the impeded rainfall infil-tration had a stronger effect on the water balance than the reduced evaporation. This indicate an ineffi-cient rainwater use in contrast to arid climates. PM changed the water cycling in the ridges from down-ward directed water flows to lateral water flows from furrows to ridges. This reduced nitrogen leaching in the topsoil (0–10 cm) in the strawberry establishment period. The plastic mulches avoided aggregate breakdown due to rapid soil wetting and excess water during rainfalls and thus maintained a loose and stable soil structure in the surface soil, which prevents soil compaction and made soil less prone to erosion. PM changed carbon fluxes and transformation so that a larger total and more stable SOM was observed. Thus, the higher belowground biomass productivity under PM compensated the impeded aboveground biomass input and the temperature-induced SOM decomposition. However, SM increased the labile and total SOM in the topsoil after the first experiment year and promoted microbial growth due to the aboveground biomass incorporation. PM reduced fungicide entry into soil compared to SM and reduced consequently the fungal biomass reduction and the biosynthesis of the mycotoxin deoxyni-valenol. The modified microclimate under PM did not increase mycotoxin occurrence. In this context, PM poses no risk for an increased soil contamination, impairing soil quality. This PhD thesis demon-strated that the PM effects on soil can vary depending on time, season and soil depth, which emphasizes the importance to include soil depth and time in future studies.
Compared to semiarid and arid regions, the PM effects found in this PhD thesis were small, absent or in another way. I attributed this to the fact that PM under humid climate reduced instead of increased soil moisture and that SM had due to straw und strawberry canopy a similar ‘covering effect’ as PM. Thus, generalizing the PM effects on soil across different climates seems hardly possible as they differ in type and extent depending on climate. A differentiated consideration is hence necessary to evaluate the PM effects on soil quality. I conclude that PM under temperate, humid climate might contribute to reduce soil degradation (e.g., SOM depletion, erosion, nutrient leaching, soil compaction and soil contamina-tion), which sustains soil quality and helps to enable a sustainable agricultural intensification. However, further research is necessary (1) to support my findings on a larger scale, longer time periods and across various soil and crop types, (2) to address remaining open questions and (3) to develop optimization to overcome the critical aspects of PM (e.g. macro- and microplastic waste in soil, mulch disposal).
For software engineers, conceptually understanding the tools they are using in the context of their projects is a daily challenge and a prerequisite for complex tasks. Textual explanations and code examples serve as knowledge resources for understanding software languages and software technologies. This thesis describes research on integrating and interconnecting
existing knowledge resources, which can then be used to assist with understanding and comparing software languages and software technologies on a conceptual level. We consider the following broad research questions that we later refine: What knowledge resources can be systematically reused for recovering structured knowledge and how? What vocabulary already exists in literature that is used to express conceptual knowledge? How can we reuse the
online encyclopedia Wikipedia? How can we detect and report on instances of technology usage? How can we assure reproducibility as the central quality factor of any construction process for knowledge artifacts? As qualitative research, we describe methodologies to recover knowledge resources by i.) systematically studying literature, ii.) mining Wikipedia, iii.) mining available textual explanations and code examples of technology usage. The theoretical findings are backed by case studies. As research contributions, we have recovered i.) a reference semantics of vocabulary for describing software technology usage with an emphasis on software languages, ii.) an annotated corpus of Wikipedia articles on software languages, iii.) insights into technology usage on GitHub with regard to a catalog of pattern and iv.) megamodels of technology usage that are interconnected with existing textual explanations and code examples.
Enterprise Collaboration Systems (ECS) werden zunehmend als Kernkomponenten des digitalen Arbeitsplatzes in Unternehmen eingesetzt, die mit der Implementierung dieser neuen Softwaregattung jeweils unterschiedliche Ziele für die innerbetriebliche Zusammenarbeit verfolgen. Diese Ziele werden in der Praxis oftmals nicht eindeutig genug formuliert. Der Einsatz von traditionellen Controlling-Kennzahlen mit dem Schwerpunkt auf Termineinhaltung und Kosten sind zudem ungeeignet, um die Realisierung des individuellen Nutzens von ECS zu messen. Diese Forschungsarbeit beschreibt die Entwicklung und Anwendung des Benefits Scorecards for Collaboration Platforms in Enterprises (SCoPE) Frameworks, das als ein Rahmenwerk für die kennzahlengestützte Nutzenmessung von ECS dient und an dem Goal-Question-Metrics-Approach der NASA sowie der Balance Scorecard von Kaplan & Norton angelehnt ist. Die Ergebnisse tragen zu einem breiteren Verständnis der kennzahlenbasierten Nutzenanalyse für ECS in Organisationen bei. Das Benefits-SCoPE-Framework wurde in enger Zusammenarbeit mit Experten aus 16 Anwenderunternehmen im Rahmen der Initiative IndustryConnect entwickelt. In einem design-orientierten Ansatz wurde ein ausgewählter Methodenmix angewandt, inklusive Experteninterview, Fokusgruppe, Workshop und Card Sorting. Der von Anwenderunternehmen erwartete Nutzen des ECS wird in spezifische, durch Kennzahlen beantwortbare Fragestellungen umformuliert und fragmentiert. Insgesamt konnten so 313 nutzenorientierte Fragen von drei Anwenderunternehmen identifiziert werden. Die durchgeführte Kategorisierung der Fragen verdeutlicht zum einen das gemeinsame Verständnis der Unternehmen hinsichtlich der entscheidenden Faktoren für die Nutzenrealisierung von ECS und zum anderen die Nutzen-ziele, die die Unternehmen durch den Einsatz des ECS anvisieren. Die Entwicklung und Erhebung von Kennzahlen zur quantitativen Beantwortung von ausgewählten Fragestellungen wird mit funktions-fähigen Prototypen auf einer operativen Kollaborationsplattform demonstriert, die seit mehr als sieben Jahren im Einsatz ist und mehr als 5.000 registrierte Benutzer aufweist. Die Kennzahlenentwicklung, die Auswahl der Datenerhebungsmethode, die Durchführung der Messung sowie die Interpretation der Messergebnisse werden im Framework durch die Verwendung von Benefits Scorecards unterstützt. Die individuelle Orchestrierung mehrerer Benefits Scorecards repräsentiert die Struktur eines Ordnungssystems zur ECS-Nutzenanalyse in Anwenderunternehmen und verdeutlicht das Vorgehen zur Erhebung der äquivalenten Daten.
The ongoing loss of species is a global threat to biodiversity, affecting ecosystems worldwide. This also concerns arthropods such as insects and spiders, which are especially endangered in agricultural ecosystems. Here, one of the main causing factors is management intensification. In areas with a high proportion of traditionally managed grassland, extensive hay meadows that are cut only once per year can still hold high levels of biodiversity, but are threatened by conversion into highly productive silage grassland. The Westerwald mountain range, western Germany, is such a region. In this thesis, I compare the local diversity of bees, beetles, hoverflies, leafhoppers, and spiders of five grassland management regimes along a gradient of land-use intensity. These comprise naturally occurring grassland fallows, three types of traditionally managed hay meadows, and intensively used silage grassland. By using three different sampling methods, I recorded ground-dwelling, flower-visiting, and vegetation-dwelling species. The results show that in most cases species richness and diversity are highest on fallows, whereas variation among different managed grassland types is very low. Also, for most sampled taxa, fallows harbour the most distinct species assemblages, while that of other management regimes are largely overlapping. Management has the largest effect on species composition, whereas environmental parameters are of minor importance. Long-term grassland fallows seem to be highly valuable for arthropod conservation, even in a landscape with a low overall land-use intensity, providing structural heterogeneity. In conclusion, such fallows should be subsidized agri-environmental schemes, to preserve insect and spider diversity.
Invasive species play increasing roles worldwide. Invasions are considered successful when species establish and spread in their exotic range. Subsequently, dispersal is a major determinant of species’ range dynamics. Mermessus trilobatus, native to North America, has rapidly spread in Europe via aerial dispersal. Here we investigated the interplay of ecological and evolutionary processes behind its colonisation success.
First, we examined two possible ecological mechanisms. Similar to other invasive invertebrates, the colonisation success of Mermessus trilobatus might be related to human-induced habitat disturbance. Opposite to this expectation, our results showed that densities of Mermessus trilobatus decreased with soil disturbance in grasslands suggesting that its invasion success was not connected to a ruderal strategy. Further, invasive species often escape the ecological pressures from novel enemies in their exotic ranges. Unexpectedly, invasive Mermessus trilobatus was more sensitive to a native predator than native Erigone dentipalpis during our predator susceptibility trials. This indicates that the relation between the invasive spider and its native predator is dominated by prey naïveté rather than enemy release.
The remaining three chapters of the thesis investigated the dispersal behaviour of this invasive species. Hitherto, studies of passive aerial dispersal used wind as the primary dispersal-initiating factor despite a recent demonstration of the effects of the atmospheric electric fields on spiders’ pre-dispersal behaviour. During our experiments, only the wind facilitated the flight, although electric fields induced pre-dispersal behaviour in spiders. Consequently, studies around passive aerial dispersal should control electric fields but use wind as a stimulating factor.
Rapidly expanding species might be disproportionately distributed in their exotic range, with an accumulation of dispersive genotypes at the leading edge of their range. Such imbalanced spatial segregation is possible when the dispersal behaviour of expanding species is heritable. Our results showed that the dispersal traits of Mermessus trilobatus were heritable through both parents and for both sexes with recessive inheritance of high dispersal ability in this species.
Following the heritability experiments, we documented an accelerated spread of Mermessus trilobatus in Europe and tested whether dispersal, reproduction or competing ability was at the source of this pattern. Our results showed that the accumulation of more mobile but not reproductive or competitive genotypes at the expansion front of this invasive species gave rise to an accelerated range expansion by more than 1350 km in under 45 years.
Invasive Mermessus trilobatus is inferior to native sympatric species with respect to competing ability (Eichenberger et al., 2009), disturbance tolerance and predation pressure. Nevertheless, the species successfully established in its exotic range and spread by accelerating its expansion rate. Rapid reproduction that balances the high ecological pressures might be the other potential mechanism behind its colonisation success in Europe and deserves further investigation.
Harvesting Season?
(2022)
Efforts to induce customers to buy groceries through the Internet have existed for around twenty years. Early on, the market structures of the digital grocery trade were still strongly fragmented and poorly coordinated. Due to the technological advancement in the past decade, the digital purchase of groceries has become more attractive. The adoption rate of these services varies greatly between different regions. In Germany in particular, the digital grocery trade is stagnating at a comparatively low level. In this regard, this dissertation analyzes both the retail-side market structures and the expectations and obstacles of German consumers.
The year 2020 connotes a turning point for the online grocery trade, as daily routines such as grocery shopping were subject to strict regulations imparted at a governmental level in order to reduce COVID-19 infections. At the same time, despite this opportunity, the digital grocery trade has not yet established itself nationwide in Germany. This can be attributed to a lack of investments, but also to inadequate digitization measures. A stronger synchronization between the digital and stationary offer, better integration of digital food services at a regional level as well as adapted, target group-appropriate digital solutions for the efficient breakdown of usage barriers will benefit service usage. The importance of stable food chains and distribution channels was illustrated by the COVID-19 pandemic. Further research should help to develop the digital food trade into a stable and sustainable supplementation of the stationary store.
Die Arbeit stellt eine Systematisierung der wissenschaftsphilosophischen Gedanken der klassischen Pragmatisten (Charles S. Peirce, William James, John Dewey) dar.
Deren Erfahrungstheorie sowie die Bestimmung des Verhältnisses von Theorie und Praxis bilden die Grundlage einer holistischen Wissenschaftsphilosophie.
Die exemplarische Anwendung auf klassische wissenschaftstheoretische Fragestellungen zeigt die Aktualität des Ansatzes.
Today’s agriculture heavily relies on pesticides to manage diverse pests and maximise crop yields. Despite elaborate regulation of pesticide use based on a complex environmental risk assessment (ERA) scheme, the widespread use of these biologically active compounds has been shown to be a threat to the environment. For surface waters, pesticide exposure has been observed to exceed safe concentration levels and negatively impact stream ecology leading to the question whether current ERA schemes ensure a sustainable use of pesticides. To answer this, the large-scale “Kleingewässer-Monitoring” (KgM) assessed the occurrence of pesticides and related effects in 124 streams throughout Germany, Central Europe, in 2018 and 2019.
Based on five scientific publications originating from the KgM, this thesis evaluated pesticide exposure in streams, ecological effects and the regulatory implications. More than 1,000 water samples were analysed for over 100 pesticide analytes to characterise occurrence patterns (publication 1). Measured concentrations and effects were used to validate the exposure and effect concentrations predicted in the ERA (publication 2). By jointly analysing real-world pesticide application data and measured pesticide mixtures in streams, the disregard of environmental pesticide mixtures in the ERA was evaluated (publication 3). The toxic potential of mixtures in stream water was additionally investigated using suspect screening for 395 chemicals and a battery of in-vitro bioassays (publication 4). Finally, the results from the KgM stream monitoring were used to assess the capability to identify pesticide risks in governmental monitoring programmes (publication 5).
The results of this thesis reveal the widespread occurrence of pesticides in non-target stream ecosystems. The water samples contained a variety of pesticides occurring in complex mixtures predominantly in short-term peaks after rainfall events (publications 1 & 4). Respective pesticide concentration maxima were linked to declines in vulnerable invertebrate species and exceeded regulatory acceptable concentrations in about 80% of agricultural streams, while these thresholds were still estimated partly insufficient to protect the invertebrate community (publication 2). The co-occurrence of pesticides in streams led to a risk underestimated in the single substance-oriented ERA by a factor of about 3.2 in realistic worst-case scenarios, which is further exacerbated by a high frequency at which non-target organism are exposed to pesticides (publication 3). Stream water samples taken after rainfall caused distinct effects in bioassays which were only explainable to a minor extent by the many analytes, indicating the relevance of unknown chemical or biological mixture components (publication 4). Finally, the regulatory monitoring of surface waters under the Water Framework Directive (WFD) was found to significantly underestimate pesticide risks, as about three quarters of critical pesticides and more than half of streams at risk were overlooked (publication 5).
Essentially, this thesis involves a new level of validation of the ERA of pesticides in aquatic ecosystems by assessing pesticide occurrence and environmental impacts at a scale so far unique. The overall results demonstrate that the current agricultural use of pesticides leads to significant impacts on stream ecology that go beyond the level tolerated under the ERA. This thesis identified the underestimation of pesticide exposure, the potential insufficiency of regulatory thresholds and the general inertia of the authorisation process as the main causes why the ERA fails to meet its objectives. To achieve a sustainable use of pesticides, the thesis proposes substantial refinements of the ERA. Adequate monitoring programmes such as the KgM, which go beyond current government monitoring efforts, will continue to be needed to keep pesticide regulators constantly informed of the validity of their prospective ERA, which will always be subject to uncertainty.
Eine Ursache des Insektenrückgangs ist die Abnahme der für Arthropoden wichtigen Lebensräume. Der kleinstrukturierte Obstanbau als Dauerkultur mit vielfältigen Strukturen (Bäume, Grünland, offener Boden) kann als Refugium wirken. Gerade Dauerkulturen, welche über viele Jahre bestehen bleiben, können einen großen ökologischen Wert für Insekten und Spinnentiere darstellen, wenn die negativen Einflüsse der Bewirtschaftung durch gezielte Maßnahmen minimiert werden. Im Gegensatz zu den gut untersuchten Streuobstwiesen liegen bisher nur wenige oder ungenaue Daten über die Arthropodenfauna in Erwerbsobstanlagen vor. Ziele dieser Arbeit sind eine genauere Erfassung der Arthropodenfauna in Erwerbsobstanlagen, Benennung der Einflussfaktoren und Erarbeitung einer indikatorgestützten Bewertungsmethode mit Entwicklung von Maßnahmen zur Förderung der Biodiversität. Es wurde eine intensive Erfassung der Insekten und Spinnentiere auf Basis von Individuenzahlen, Verteilung der Tiere auf Großgruppen, Artenzahlen der Käfer (inkl. Rote Liste) und Wanzen, deren Diversität und der sie beeinflussenden Faktoren auf vier Erwerbsobstflächen und einer Streuobstwiese als Referenzfläche in der Gemeinde Zornheim (Rheinland-Pfalz) untersucht. Mittels des erarbeiteten Bewertungsbogens wurden die Auswirkungen der fünf Faktorenkomplexe: Sonderstrukturen, Anlagenstruktur, Beschattung, Mahdregime und Einsatz von Pflanzenschutzmitteln auf die Arthropodenfauna erhoben und die auf der Fläche zu erwartende Biodiversität ermittelt. Die visuelle Darstellung der Einflussfaktoren mit Netzdiagrammen zeigt biodiversitätsbeeinträchtigende Faktoren und ermöglicht so Empfehlungen zur Aufwertung der Biodiversität. Die Bewertungsmethode kann nach Verifizierung im Rahmen von erfolgsorientierten Agrarumwelt- und Klimamaßnahmen (AUKM), zur Anerkennung von Kompensationsmaßnahmen (z.B. PIK) und zur Ermittlung des ökologischen Wertes (Ökosystemdienstleistung) von Obstanlagen genutzt werden. In modifizierter Form könnte es ebenfalls im Bereich der Flächenbewertung in Landschafts- und Bauleitplanung eingesetzt werden.