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Entwicklung und Evaluation von bioverfahrenstechnischen Kontexten und Bildungsmedien für das ingenieurs- und naturwissenschaftliche Umfeld
Get PDFUniversitäre Forschung schafft täglich neue innovative naturwissenschaftliche Erkenntnisse, die wesentliche Bedeutung für gesellschaftsrelevante Kontexte, wie Maßnahmen zum Klimaschutz oder neue medizinische Behandlungsmethoden, tragen. Für die Gesellschaft bleiben jedoch hinter diesen neuen Erkenntnissen und Methoden die fachlich relevanten Hintergründe oftmals unerklärt, wodurch Missstände entstehen können. Fachdidaktische Transferforschung soll diese resultierende Lücke zwischen universitärer Forschung und Gesellschaft beleuchten und Brückenelemente entwickeln. In Anlehnung dazu stehen die Konzeption und Evaluation von Bildungsangeboten zu forschungsorientierten Kontexten aus der Kooperation von Fachdidaktik und Fachwissenschaft im Fokus der vorliegenden Arbeit. Inwiefern moderne digitale Bildungsmedien, wie Augmented Reality (AR), Virtual Reality (VR) oder digitale Zwillinge, die dafür notwendige didaktische Reduktion der forschungsorientierten Themen und Visualisierung der komplexen fachlichen Zusammenhänge unterstützen, ist ebenso Gegenstand der im Folgenden dargestellten Forschungsarbeit. Ziel ist es das disziplinäre Silo-Denken im MINT-Bereich aufzubrechen und kontextualisiertes Lernen zu fördern, um theoretisches Wissen mit realen Problemlösungen fächerübergreifend zu verknüpfen. Die vorliegende Arbeit trägt mit den forschungsorientierten Bildungsangeboten zur Entwicklung hin zu einem attraktiven, motivierenden und praxisorientierten MINTUnterricht in der digitalen Welt bei, um gleichzeitig die zukünftigen Generationen für MINT zu begeistern und im Sinne der Nachhaltigkeitsziele die Qualität der Bildung zu steigern
Die Rolle von landwirtschaftlichen Betrieben bei der Erreichung der Sustainable Development Goals anhand eines Fallbeispiels aus Ägypten
Get PDFDie Rolle von landwirtschaftlichen Betrieben bei der Erreichung der Sustainable Development Goals anhand eines Fallbeispiels aus Ägypten. Enthält eine Länderstudie zu Ägypten und eine Fallstudie zu einem Demeter-Bauernhof in Ägypten. Als Methodik wird das Integrierende Nachhaltigkeitsdreieck nach Hauff angewandt
Cyclometallierte Iridium(III)-Komplexe mit N,N‘- und C,N-Donorliganden: Synthese, Charakterisierung und Anwendungen
Get PDFIn dieser Arbeit wird die Synthese bis- und tris-cyclometallierter Iridium(III)-Komplexe mit aminosubstituierten Bipyrimidin- und Pyridinylpyrimidinliganden ausgehend von Tetrakis(2-phenylpyridin-C,N)(-dichlorido)diiridium(III) vorgestellt. Beide Ligandentypen gehen mit dem Iridiumzentrum kinetisch begünstigt eine N,N‘-Koordination ein und bilden ionische zweifach cyclometallierte Komplexe. Die unbegünstigte C,N-Koordination dieser Liganden gelang über den intrinsisch basischen Tetrakis(2-phenylpyridin-C,N)(-dihydroxido)diiridium(III) und führte zu ungeladenen dreifach cyclometallierten Komplexen. Die Basizität dieses Komplexes konnte in der katalytischen Transferhydrierung von Ketonen belegt werden. Anschließend wurden die Struktur und photophysikalischen Eigenschaften der dargestellten bis- und tris-cyclometallierten Komplexe untersucht. Es konnte festgestellt werden, dass die dreifach cyclometallierten Ir(III)-Komplexe längerwelliges Licht bei längeren Phosphoreszenzlebensdauern und höheren Quantenausbeuten als ihre N,N‘-koordinierten Homologa aufweisen
Adaptoren und ikonische Gesten in Erzählungen: Eine multimodale Untersuchung der Referentialität in der Primarstufe
Get PDFDas Zusammenspiel von Körperbewegungen bzw. Gesten und Sprache in Erzählungen von Grundschülern steht im Fokus dieser Arbeit. In dieser multimodalen Untersuchung werden nicht nur syntaktische Strukturen und Muster untersucht, die Erzählungen ausmachen, sondern auch Körperbewegungen, die während einer Erzählung produziert werden. Die Erforschung von Erzählungen als multimodale und körperliche Handlungen steht im Fokus der Arbeit. Dabei werden gewonnene Erkenntnisse auch im Hinblick auf vorhandene Modelle, die die Multimodalität des Erzählens nicht berücksichtigen, überprüft, beispielsweise textgrammatische bzw. referentielle Effekte, die auch multimodal realisiert werden, und Kohäsionsgesten, die, unter Umständen mit sprachlichen kohäsionsstiftenden Mitteln korrelieren. Ein weiterer Schwerpunkt liegt in der Untersuchung der sprachlichen sowie gestischen Entwicklung von Kindern im Alter zwischen sechs und zehn Jahren. Hierbei wird gezeigt, dass verschiedene Erzählstimuli bzw. -anlässe auch zu unterschiedlichen Ergebnissen sowohl in der Quantität und Art der Gesten als auch in der Art der sprachlichen Konstruktion des textuellen Sinnzusammenhangs führen.This work focuses on the interplay between body movements or gestures and language in narratives told by primary school children. This multimodal study examines not only the syntactic structures and patterns that make up narratives, but also the body movements produced during a narrative. The research focuses on narratives as multimodal and physical actions. The findings are also examined in relation to existing models that do not take into account the multimodality of storytelling, for example, text-grammatical or referential effects that are also realised multimodally, and cohesion gestures that may correlate with linguistic means of creating cohesion. Another focus is the investigation of the linguistic and gestural development of children between the ages of six and ten. Here, it is shown that different narrative stimuli or occasions also lead to different results in terms of both the quantity and type of gestures and the type of linguistic construction of the textual context
Who supports the disadvantaged? How justice sensitivity, social identification, and political ideology shape solidarity-based action
Get PDFAs global challenges and humanitarian crises increase, the presence of injustice and inequality becomes ever-more apparent. This dissertation addresses the growing need to learn more about the drivers of support for disadvantaged groups. Using multiple pathways, this research focuses on four major factors, aiming to explore how justice sensitivity – a personality trait – and social identification – rooted in intergroup dynamics – both relate to solidarity-based action across various contexts, and to examine their relationship, as well as their interplay with intergroup emotions such as moral outrage and sympathy. Further, it aims to investigate the impact of political ideology, particularly liberalism, on attribution biases and their influence on emotional and behavioral responses when confronted with norm-violating behaviors by members of disadvantaged groups that one supports. Taken together, the findings indicate that justice sensitivity, particularly other-related justice sensitivity (JS-other), seems to be a reliable indicator of solidarity-based attitudes and behaviors. The significant role of social identification, especially on a superordinate level, is also supported, albeit with varying effects depending on the context. In an overall model, results suggest that individuals with higher JS-other tend to identify more strongly with higher levels of identification, which in turn leads to stronger intergroup emotions. These emotions then contribute to more solidarity-based action. Political ideology shapes how individuals attribute the causes of norm-violating behaviors, with liberals demonstrating a tendency to make lower dispositional attributions when the actor is a member of a disadvantaged group. While the severity of a norm-violation amplifies dispositional attributions, the ideological biases are found to persist. The findings aim to encourage individuals to reflect on their responses to injustice and to contribute to efforts that challenge social inequality. Ultimately, the insights gained here will be discussed in regard to suggesting theoretical as well as practical contributions for promoting more equal treatment across social groups
Beitrag zur experimentellen Ermittlung des Dämpfungsverhaltens von Faser-Kunststoff-Verbunden
Get PDFFür eine dynamische Auslegung von Faser-Kunststoff-Verbunden ist die Kenntnis der Dämpfungseigenschaften notwendig. Bedingt durch eine Vielzahl von Einflussfaktoren auf das Materialverhalten hat sich bisher keine standardisierte Versuchsmethode zur Ermittlung dieser Kennwerte durchgesetzt. Um diese Forschungslücke zu schließen adressiert die vorliegende Arbeit die Dämpfungsbestimmung durch unterschiedliche Versuchsmethoden. Hierzu werden mittels Dynamisch-Mechanischer Analyse und freien Ausschwingversuchen die Dämpfungseigenschaften von Faser-Kunststoff-Verbunden ermittelt. Geprüft werden
Verbundwerkstoffe mit einer duroplastischen und thermoplastischen Matrix, wodurch der Einfluss der Matrix untersucht wird. Zudem werden die Einflussfaktoren Faserorientierung, Belastung, Geometrie, Frequenz und Temperatur für eine umfassende Einordnung der jeweiligen Versuchsmethode analysiert. Aus einem abschließenden Vergleich beider Versuchsmethoden unter Berücksichtigung aller Einflussfaktoren werden Gestaltungshinweise für die Dämpfungsermittlung von Faser-Kunststoff-Verbunden abgeleitet.Knowledge of the damping properties is essential for the dynamic design of fibre-reinforced plastics. Due to the large number of factors influencing the material behaviour, no standardised test method has yet been established to determine these properties. In order to fill this research gap, the present work investigates the determination of damping using different test methods. The damping properties of fibre-reinforced plastics are determined using dynamic mechanical analysis and free vibration tests. Composites with a thermosetting and thermoplastic matrix are tested, whereby the influence of the matrix is investigated. Additionally, the influence of fibre orientation, load, geometry, frequency, and temperature are analyzed to provide a comprehensive classification of the respective test method. Finally, a comparison of the two test methods, taking into account all the influencing factors, is used to derive design guidelines for determining the damping of fibre-reinforced plastics
Establishing a novel platform for phycobiliprotein assembly
Get PDFA variety of organisms, including cyanobacteria, red algae and cryptophytes, perform oxygenic photosynthesis using chlorophyll-containing protein complexes and phycobiliproteins for light-harvesting. The most prominent phycobiliproteins described in literature assemble to macromolecular antenna complexes, called the phycobilisomes, to enhance oxygenic photosynthesis. Phycobiliproteins are categorized according their chromophore composition, with phycocyanins and allophycocyanins binding phycocyanobilin, while phycoerythrins can bind various bilins, such as 15,16-dihydrobiliverdin and phycoerythrobilin. Investigations of phycoerythrins often involves heterologous expression systems based on E. coli but only allow for biochemical characterization. In contrast, the utilization of expression systems in cyanobacteria, such as Synechocystis sp. PCC 6803, offer the opportunity to study phycoerythrins on a physiological level.
Consequently, this work aimed at providing a platform for heterologous phycoerythrin assembly using the cyanobacterium Synechocystis sp. PCC 6803, which naturally synthesizes allophycocyanin and phycocyanin with covalently attached phycocyanobilin. As a necessary prerequisite, phycoerythrobilin biosynthesis was established to provide the chromophore for phycoerythrin assembly. The impact of heterologous phycoerythrobilin production on the cellular physiology was assessed by growth curve experiments, oxygen evolution measurements as well as nutrient- and phycobiliprotein content determination. Despite a reduction in the growth rate, physiological effects were negligible. In addition, the influence of phycoerythrobilin formation on the biochemical properties of endogenous phycobiliproteins and its consequences for phycobilisome assembly were evaluated and show covalent attachment of phycoerythrobilin to CpcA of phycocyanin. The modified phycocyanin is unable to assemble into the phycobilisome complex leading to free cytosolic phycobiliproteins. Eventually, the remaining genes necessary for the assembly of the P. marinus MED4 phycoerythrin were introduced in Synechocystis sp. PCC 6803. Although in a rather low abundance, evidence for recombinant protein production is provided. However, proper assembly of the phycoerythrin was not confirmed in this study which motivates for further optimization strategies to increase the yield of target proteins.
In summary, this work demonstrates the amenability of Synechocystis sp. PCC 6803 to modifications in its biosynthetic phycobilin pathways by heterologously producing the chromophore phycoerythrobilin. Consequently, a promising foundation for the assembly of phycoerythrins is provided. Although proper phycoerythrin assembly was not confirmed in this study, the remaining challenges are most likely of technical nature. These findings still strengthen the potential of utilizing cyanobacteria as a platform for the biochemical and physiological evaluation of phycoerythrins from otherwise inaccessible oxygenic phototrophs. Consequently, using such a platform may strongly contribute to the understanding of the structure and the mechanism of accessory light-harvesting machineries contributing to oxygenic photosynthesis
Analysis of a Competitive Respiratory Disease System with Quarantine
Get PDFThe SARS-Cov2 pandemic once more showed that new respiratory diseases can be a burden for the society. On the other hand, there are long existing respiratory pathogens such as influenza or other influenza-like illnesses (ILI) in the population. This thesis studies competing a system of two competing respiratory diseases. The focus lies especially on non-pharmaceutical interventions
(NPIs) effects, such as quarantine efficacy and study the long-time behavior depending on cross immunity and co-infections. Mathematically the system is investigated towards critical points, disease threshold and multi-pathogen effects in the dynamics of each strain and their co-infections.
Besides, our examination includes identifying and analyzing the underlying determinants of the backward bifurcation phenomenon. We also incorporate empirical data on Influenza and SARS-CoV-2 to prove our findings in a realistic setup.
Our results suggest that effective quarantine measures are necessary for infection management, even when the quarantine reproduction numbers are below one. Under complete immunity, a strain with a quarantine reproduction number (average number of secondary cases made by an infected person under a quarantine control) of less than one may lead to extinction, while partial cross-immunity allows for its coexistence at a low level. The backward bifurcation shows the
capability of the model to accommodate the simultaneousness of the disease-free equilibrium with up to four endemic equilibria. Co-infections and imperfect quarantine actions pose significant challenges in containing outbreaks, sustaining the outbreak potential even with successful control of individual virus strains. The study also emphasizes the significance of age-structured
models in capturing the dynamics of influenza and SARS-CoV-2, surpassing traditional all-age group models. Again, our investigation delivers insights into the interplay between the influenza and SARS-CoV-2 transmission rates relations. This interaction remains consistently significant, especially in scenarios involving partial cross-immunity. Accordingly, our study suggests that comprehensive interventions targeting both pathogens (simultaneously) may be necessary for effectively curbing the spread of both infections in concurrent environments.Die SARS-CoV-2-Pandemie hat gezeigt, dass neue Atemwegserkrankungen eine Belastung für die Gesellschaft sein können. Andererseits gibt es lang bestehende Atemwegserreger wie Influenza
oder andere grippeähnliche Krankheiten (ILI) in der Bevölkerung. Diese Arbeit untersucht ein
System aus zwei konkurrierenden Atemwegserkrankungen. Besonders wird auf die Wirkung
nicht-pharmazeutischer Interventionen (NPI), wie die Wirksamkeit von Quarantänemaßnahmen,
und das Langzeitverhalten in Abhängigkeit von Kreuzimmunität und Co-Infektionen eingegangen.
Mathematisch wird das System im Hinblick auf kritische Punkte, Krankheitsschwellen
und Mehrfacherreger-Effekte in der Dynamik jedes Stammes und ihrer Co-Infektionen untersucht.
Darüber hinaus umfasst unsere Untersuchung die Identifizierung und Analyse der zugrunde liegenden Determinanten des Rückwärtsbifurkationsphänomens. Wir integrieren auch
empirische Daten zu Influenza und SARS-CoV-2, um unser Verständnis der Dynamik der Interaktionen zwischen mehreren Stämmen zu erweitern.
Unsere Ergebnisse deuten darauf hin, dass wirksame Quarantänemaßnahmen für das Infektionsmanagement notwendig sind, selbst wenn die Quarantäne-Reproduktionszahlen unter eins
liegen. Bei vollständiger Immunität kann ein Stamm mit einer Quarantäne-Reproduktionszahl
von weniger als eins zur Auslöschung führen, während teilweise Kreuzimmunität seine Koexistenz auf niedrigem Niveau ermöglicht. Die Rückwärtsbifurkation zeigt die Fähigkeit des Modells,
das gleichzeitige Vorhandensein des krankheitsfreien Gleichgewichts mit bis zu vier endemischen Gleichgewichten zu berücksichtigen. Dennoch stellen Co-Infektionen und unvollkommene
Quarantänemaßnahmen erhebliche Herausforderungen bei der Eindämmung von Ausbrüchen dar und halten das Ausbruchspotenzial aufrecht, selbst bei erfolgreicher Kontrolle einzelner Virus-Stämme. Die Studie betont auch die Bedeutung altersstrukturierter Modelle zur Erfassung der
Dynamik von Influenza und SARS-CoV-2, die herkömmliche Modelle für alle Altersgruppen übertreffen. Unsere Untersuchung liefert erneut Einblicke in das Zusammenspiel zwischen den
Übertragungsraten von Influenza und SARS-CoV-2. Diese Interaktion bleibt durchweg bedeutsam, insbesondere in Szenarien mit teilweiser Kreuzimmunität. Entsprechend legt unsere Studie
nahe, dass umfassende Interventionen, die auf beide Erreger gleichzeitig abzielen, notwendig sein
können, um die Verbreitung beider Infektionen in gleichzeitigen Umgebungen wirksam einzudämmen
Walking alone on empty streets: Reconsidering the effects of social isolation and loneliness on mental health
Get PDFWhen COVID-19 was declared a global pandemic by the World Health Organization (WHO), concerns quickly arose that restrictions on social contact and physical distancing could lead to a mental health crisis due to the potentially higher prevalence of social isolation and loneliness in the general population. These concerns were based on the belief that social isolation and loneliness pose significant risks to the mental health of people who experience them, commonly referred to as the causation hypothesis. Extensive research has linked both conditions to outcomes such as depression, anxiety, and suicide. However, evidence of causation has been limited because few studies have attempted to rule out alternative explanations for the observed associations. It is equally plausible that people experience social isolation or loneliness because of the presence of mental health problems (direct selection hypothesis) or because of stable characteristics that make them vulnerable to these problems (indirect selection hypothesis). Against this background, the purpose of this thesis is to improve our understanding of why social isolation and loneliness are associated with mental health problems. As an initial contribution, theoretical arguments for causation and selection have been reviewed and systematised into a broader set of mechanisms. Then, a brief review of empirical research to assess the extent to which previous studies distinguish between the three explanations has been presented. The review revealed that empirical evidence of the negative effects of social isolation and loneliness on mental health is not as clear-cut as often assumed. Finally, four empirical studies were conducted using advanced techniques of panel data analysis to rule out selection as an alternative explanation and to provide new evidence for the causation hypothesis. In addition, the empirical studies examined whether the conclusions regarding causation remained robust across multiple measurement approaches and broader sociodemographic groups (i.e., men and women, older and younger people). Overall, the results support the causation hypothesis and show that social isolation and loneliness are associated with worse mental health, even when selection is considered as a competing explanation. Convincing evidence of causation emerged across all sociodemographic groups, and measurement approaches did not affect the substantive conclusions. These findings have several practical implications. First, concerns about the COVID-19 pandemic triggering a mental health crisis by increasing the prevalence of social isolation and loneliness in the general population were well founded. Second, the critical importance of addressing social isolation and loneliness is highlighted by strong support for the causation hypothesis. Because of the continued high prevalence of social isolation and loneliness worldwide after the pandemic and their impacts on mental health, both conditions cause great human suffering and impose significant costs on health care systems
Wireless Low Power Edge Devices and Transient Computing Systems with Energy Harvesting
Get PDFSince the prediction of Gordon Moore in 1965, known as Moore’s Law [1], the in-
tegration density and performance of integrated circuits have increased continuously. As
a result, integrated circuits are enabling ever-new possibilities for decades and are being
used in more and more areas of applications. This led to a fast growing demand of micro-
electronic systems ranging from, e.g., edge devices for the Internet of Things (IoT) over
industrial control systems up to computationally intensive machine learning applications.
However, within the last years, the increased environmental awareness and the efforts
to create a more sustainable world have shed light on the darker side of this development:
The increasing energy demand for computing. In fact, the global demand for computa-
tional energy and battery capacity is increasing exponentially. In order to counteract this
development, experts call for fundamental changes in microelectronic systems design that
enable significantly better energy efficiencies of electronic devices [2]. Suggestions range
from an increased use of advanced computing platforms that allow for application-specific
hardware-software co-designs up to an improvement of edge computing capabilities to
gradually replace conventional computing. More radical proposals request for a consistent
utilization of renewable energy sources [3] or propose specific paradigm changes in com-
monly battery-powered application fields by calling for a battery-less internet of things [4].
This thesis proposes new design approaches for energy and environmentally friendly
embedded systems in different areas of application that are fit for the future. For the in-
dustrial area, this thesis addresses model predictive control (MPC) systems. A new op-
timization strategy for the resource-intensive MPC algorithms is demonstrated to enable
their implementation on low power and low-cost FPGAs. Regarding edge computing, new
design approaches are presented to improve the computing capabilities for mobile battery-
powered devices. These approaches enable ultra-low power communication security fea-
tures for IoT systems and present new precise time synchronization principles for wireless
sensor networks.
A clear emphasis of this thesis is on the improvement of embedded systems that are
solely powered by energy harvesting. Such battery-less systems are also known as inter-
mittent or transient computing systems, as they do not have a reliable energy basis. One of
the major issues that hamper the widespread use of this sustainable system concept is the
reactive nature of state-of-the-art transient computing approaches, i.e., the system is com-
pletely and utterly dependent on the transiency of its energy harvesting source. As a solu-
tion, this thesis proposes new hardware and software design methods towards a proactive
transient computing. These methods are dedicated to kinetic and thermal energy harvesting
technologies and enable a predictive and adaptive power loss management to pave the road
for yet infeasible applications fields