What is OPUS?
Siegen University Library provides a free of charge repository named OPUS Siegen (OPUS = Online PUblication Server) with the purpose to publish, archive and retrieve electronical documents produced at the University of Siegen.
What will you find here?
You will find Open-Access-Publications from all faculties of Siegen University and from the "universi" publishing house. The University Library applies acknowledged quality standards and offers support for publishing your documents.
How to participate?
For uploading documents, sign on to OPUS via Shibboleth using your ZIMT-Account.
Recently published
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Publication Open Access Der narzisstische Sozialcharakter als treibende Kraft für die Professionalisierung von Lehrkräften(2026)The increasing strain on teachers is reflected in high rates of sick leave as well as forfeit income due to reduced working hours and the wide-ranging use of early retirement arrangements. The potential of pedagogical professionalism to play a protective role in this context has, however, rarely been addressed so far. This PhD thesis addresses this issue. It examines what pedagogical professionalism must look like today in order for teachers to cope with current challenges in a way that promotes learning, is appropriate, and takes their own health into account. To this end, the contemporary social character is first analyzed, which, can be characterized as narcissistic due to prevailing societal conditions. This facilitates that corresponding dispositions may be passed on to students, for example in the form of appealing and widely disseminated narratives. As a result the narcissistic social character may lead to challenges in everyday school life. Dealing with these in a way that promotes learning therefore requires a modern form of pedagogical professionalism that takes these premises into account. The thus developed argumentation is then related to the status quo by means of case studies, making it possible to identify both resources and developmental potential within the current state of pedagogical professionalism.Source Type:3 4 - Some of the metrics are blocked by yourconsent settings
Publication Open Access Medienepistemologie sympoietischer Weltbezüge. Zur Kritik eines ikonisch-humanistischen Anthropozentrismus(2026)The article examines the epistemic conditions of human world relations in the Anthropocene by adopting a media-philosophical perspective on the interplay between anthropocentrism, visuality, and the medial figurations of epistemic premises. It departs from the diagnosis of a disrupted communication between humans and their environment(s), a disruption rooted in a humanistically grounded anthropocentric worldview. This worldview manifests not only in practices of distancing objectification and universalization but also in medial forms through which “world” becomes visible and thinkable. Using the Blue Marble—NASA’s popular photograph of Earth—as a case study, the article analyzes how an icon of planetary wholeness stabilizes the epistemic architecture of a quasi-cosmic observer standpoint. The image generates a normative holism that brackets the processual, conflictual, and situated character of terrestrial relations, thereby reproducing a hierarchical relation between observer and observed. In the objectification and utilitarian reduction of the Earth, the same circular logic of control is reiterated—one that has contributed to the ecological disruptions characteristic of the Anthropocene. Against this iconic totalization, the article proposes a sympoietic approach that foregrounds the participation of non-human actors in world-making and conceptualizes media as instruments for rendering their forces and agencies perceptible. Media are thus understood as partial, relational, and processual actors. A media epistemology of sympoietic world relations makes it possible to conceive mediality beyond the ideals of a god-like observer position: as a situated, dependent, and co-produced mode of being-in-the-world. In doing so, the article sketches an epistemic model that does not seek to transcend the centrality of the human in thought, but rather aims to situate human existence within the relational entanglements between humans and their environment(s).5 2 - Some of the metrics are blocked by yourconsent settings
Publication Open Access Bridging the Gap: Assessing the Realism of Simulators in Human-Computer Interaction(2025-11-07)The "Automation Paradox" in safety-critical domains shifts human operators into supervisory roles, degrading their skills while still requiring them to act as the ultimate cognitive failsafe during critical events. This necessitates new methods to monitor the operator's cognitive state, but research is hampered by a "fidelity gap". High-fidelity simulators are often inaccessible, while accessible low-fidelity tools may not produce generalizable results, creating a need for a new approach to simulator-based research. This dissertation addresses this gap by proposing and validating the concept of psychophysiological realism, a criterion for simulator validity based on whether an environment feels real to an operator's cognitive and autonomic nervous systems. The core methodological contribution is a framework for instrumenting accessible simulation platforms with multimodal sensor suites, turning them into valid scientific instruments for assessing operator state and behavior. The research progressed through four empirical studies. First, the approach's feasibility was established by instrumenting a web-based emergency dispatch simulator (LstSim), showing it could capture psychophysiological responses to stress. This method was then validated by correlating objective respiration data, which increased by 13.08% under high load, with subjective NASA-TLX workload scores, confirming the simulator could reliably measure cognitive load. The framework's scalability was subsequently demonstrated by successfully generalizing the methodology to an Air Traffic Control (ATC) simulation with an expanded, integrated sensor suite. Finally, to assess behavioral fidelity, a study comparing cyclist movement in a virtual reality (VR) simulator to the real world empirically quantified a "fidelity gap". It revealed that while core biomechanics transferred well, significant divergences emerged in higher-order control strategies and emotional responses. Collectively, this research delivers an integrated and validated methodology that connects the objective measurement of an operator's cognitive state within a simulator to the quantitative assessment of that environment's behavioral fidelity. The framework provides the sensory input for developing intelligent adaptive interfaces, enables more rigorous, state-aware training, and supports an evidence-based approach to designing cognitively ergonomic systems in safety-critical domains.Source Type:2 27 - Some of the metrics are blocked by yourconsent settings
Publication Open Access Design, Synthesis, and Biological Evaluation of a Modular Polymer-based Platform for Antimicrobial Photodynamic Therapy(2025-12-01)The emergence of antibiotic-resistant bacteria, particularly in respiratory infections, presents an urgent need for alternative therapeutic approaches. This thesis describes the development of polymer-based antimicrobial photodynamic therapy systems designed specifically for treating Pseudomonas aeruginosa respiratory infections. Two complementary synthetic strategies were employed to create functional polymeric materials incorporating photosensitizers and other active ingredients (biofilm-disrupting agents). The first approach involved post-polymerization modification of active ester polymers, enabling controlled incorporation of both ruthenium complexes and phenalenone derivatives as photosensitizers. The second strategy utilized direct free radical polymerization of photosensitizer-containing monomers alongside functional comonomers. Both approaches successfully yielded water-soluble polymers intended for nebulization-based delivery. Compared to free photosensitizers, these polymer-based systems offer advantages including enhanced local drug concentration through multivalent presentation and improved solubility, addressing key limitations of conventional photosensitizers. Comprehensive biological evaluation highlighted various properties of the polymers designed with identification of structure-activity relationships. Some of these materials can effectively inactivate and/or eliminate both planktonic bacteria and biofilms upon visible light illumination, with activity maintained in physiologically relevant conditions. Notably, certain polymers also showed enhanced efficacy in high-salt environments representative for respiratory infections such as cystic fibrosis. The materials exhibited excellent biocompatibility with human bronchial epithelial cells and maintained their structural integrity and antimicrobial activity through nebulization, supporting their potential for therapeutic applications. This work establishes a promising platform for treating respiratory infections through controlled, light-activated antimicrobial activity, offering advantages over conventional antibiotic treatments while maintaining compatibility with clinical delivery methods.Source Type:4 5 - Some of the metrics are blocked by yourconsent settings
Publication Open Access Design, Simulation and Measurements of Graphene-based THz Antennas for Future 6G Communications(2025)The terahertz (THz) frequency band is among the key technologies being investigated for future 6G communication systems. Over the past years, wireless communications have increasingly used higher frequency bands in pursuit of greater bandwidth and integration capabilities. This technological advancement has facilitated the emergence of short-range applications, including data kiosks, wireless chip interconnects, and intra-body networks, electronic components placed within the body to monitor health. Additionally, because passive devices are smaller at higher frequencies, it is possible to fit more antennas into the same area, resulting in arrays that produce increasingly focused beams. Given the significant spreading losses and molecular absorption at this frequency range, THz communications are particularly well-suited for short-range applications where spatial limitations are key or extremely high bandwidth is necessary. Moreover, the THz and millimeter wave (mm-wave) wireless communications for intra-chip and chip-to-chip connections can enhance the already constrained wired interconnects within computing packages, helping to alleviate communication bottlenecks in future computing platforms that may contain hundreds or thousands of processors in a single package. Adopting compact antennas and transceivers as wireless interconnects within computing packages will lead to low-latency and reconfigurable communication pathways, reducing the complexity of the dense wired interconnect network. The main problem with the current wireless network inside chips is the size of the antenna. Reducing the size of a metallic antenna to just a few micrometers leads to poor performance due to the low conductivity of the metal at these small dimensions, and using such small antennas would require very high frequencies, around hundreds of THz, which are not suitable for radio frequency (RF) wireless communications due to issues with signal loss and transceiver design. Hence, technological advances in antenna development are essential for implementing future communication systems at THz frequencies. Thus, graphene-based antennas appear as the ideal complement to traditional metallic antennas due to their potential for smaller dimensions and frequency tunability in the THz range. Graphene antennas operating at THz frequencies are smaller than their metallic counterparts functioning at the same frequency, thereby advancing the boundaries of integration further. The research, design, and investigation of THz graphene-based antennas are the focus of this thesis. This work addresses the graphene material characteristics and plasmonic behaviors directly related to a functioning THz graphene-based antenna. Moreover, three different graphene-based antenna types, with different working principles, operating at THz frequencies are investigated, i.e. two different types of photoconductive antennas (graphene dipole and graphene patch antennas), and an electronic antenna (graphene patch and graphene stack patch antennas). Theoretical explanations regarding the principles of THz emission of each antenna type are presented, as well as descriptions regarding the measurement systems utilized to characterize these antennas. Studies regarding antenna emission are made by electromagnetic (EM) simulations and proper measurements. The further investigation of antenna frequency tuning and antenna efficiency in the THz range is based on simulations varying important graphene antenna characteristics. The measurements show not only THz emission from the graphene-based antennas but also the THz emission tuning of the antennas based on an electrostatic bias. Additionally, a THz graphene antenna array is studied by means of simulations. Finally, the challenges and feasibility of having efficient THz graphene-based antennas are discussed, and possible future development steps are suggested.12 729
