University of Münster
Münstersches Informations und Archivsystem für Multimediale InhalteNot a member yet
10543 research outputs found
Sort by
Implementing Augmented Reality Models in the Classroom Environment Using Merge Cubes: A Quantitative Study of the Effects on Students’ Cognitive Load and Motivation
No full textThe present study investigates the extent to which the use of Merge Cubes as haptic AR tools in the classroom—realized in construction technology lessons at a vocational college as an exemplary case—influences the cognitive load and motivation of learners. A quasi-experimental field study was conducted using a questionnaire in a pre-post design including a control group at a vocational college in Germany (North Rhine-Westphalia). During the intervention phase, the students in the experimental group worked with materials such as textbooks and worksheets that were specifically expanded to include the Merge Cube AR learning tool, while the students in the control group only used conventional learning materials. In both the pre- and post-test, the cognitive load and motivation of the learners were recorded using questionnaires. The results indicate that the use of Merge Cubes can reduce cognitive load: the extraneous cognitive load of the experimental group decreased over the course of the intervention, whereas that for the control group increased significantly in comparison. In addition, the germane cognitive load increased slightly in the experimental group, whereas that for the control group decreased. With regard to the intrinsic motivation of the learners, both groups recorded an increase, although the difference between the two groups was not significant. Based on these results, further factors influencing the effect on learning and implications for the practical use of the Merge Cube in the classroom are discussed, the concrete validation of which requires further research
neuroWalknet, a controller for hexapod walking allowing for context dependent behavior
No full textDecentralized control has been established as a key control principle in insect walking and has been successfully leveraged to account for a wide range of walking behaviors in the proposed neuroWalknet architecture. This controller allows for walking patterns at different velocities in both, forward and backward direction—quite similar to the behavior shown in stick insects—, for negotiation of curves, and for robustly dealing with various disturbances. While these simulations focus on the cooperation of different, decentrally controlled legs, here we consider a set of biological experiments not yet been tested by neuroWalknet, that focus on the function of the individual leg and are context dependent. These intraleg studies deal with four groups of interjoint reflexes. The reflexes are elicited by stimulation of the femoral chordotonal organ (fCO) or groups of campaniform sensilla (CS). Motor output signals are recorded from the alpha-joint, the beta-joint or the gamma-joint of the leg. Furthermore, the influence of these sensory inputs to artificially induced oscillations by application of pilocarpine has been studied. Although these biological data represent results obtained from different local reflexes in different contexts, they fit with and are embedded into the behavior shown by the global structure of neuroWalknet. In particular, a specific and intensively studied behavior, active reaction, has since long been assumed to represent a separate behavioral element, from which it is not clear why it occurs in some situations, but not in others. This question could now be explained as an emergent property of the holistic structure of neuroWalknet which has shown to be able to produce artificially elicited pilocarpine-driven oscillation that can be controlled by sensory input without the need of explicit innate CPG structures. As the simulation data result from a holistic system, further results were obtained that could be used as predictions to be tested in further biological experiments
Noninvasive ventromedial prefrontal cortex stimulation can enhance and impair affective learning from rewarding and threatening stimuli
No full textThe ventromedial prefrontal cortex (vmPFC) is known as a central hub involved in affective learning from appetitive/aversive stimuli, as demonstrated in numerous studies examining affective stimuli. We used vmPFC-stimulation to test whether the concept of enhanced affective learning applies to enhanced inhibition of risky decisions and overgeneralized fear. Therefore, we modulated vmPFC-excitability noninvasively via transcranial direct current stimulation (tDCS) using excitatory, inhibitory, and sham stimulation. We re-analysed previously published behavioural and magnetoencephalography data trial-wise to test whether improved learning is the mechanism underlying modulated gambling/fear generalization. Following excitatory vs. sham stimulation, participants gambled more rationally and got better at discriminating safe from threatening stimuli, as indicated by interactions between tDCS and gambling/fear stimuli. Three-way interactions with trial-number suggest that these improvements developed during the experiment. In contrast, in the inhibitory group, these abilities deteriorated over the paradigm. The neural data dovetailed with behavioural effects, in that neural correlates of modulated learning after stimulation also developed over time. Our results indicate an association between vmPFC activity and the ability to learn from appetitive/aversive stimuli. As impaired affective learning is a driving mechanism in mental disorders, these findings identify excitatory vmPFC-tDCS as a potential treatment, especially in combination with psychotherapy
Retrospektive Analyse der megaendoprothetischen Rekonstruktionen von Knie und Hüfte nach periprothetischem Infekt
No full textDiese retrospektive Studie untersucht 150 Patienten, die nach periprothetischer Infektion des Knie- und/oder Hüftgelenks mit MUTARS®-Megaendoprothesen versorgt wurden. Analysiert wurden Komplikationen, Revisionsraten, das infektfreie sowie das amputationsfreie Implantatüberleben und das Risiko von Reinfektionen. Die häufigsten Ursachen für Implantatversagen waren Reinfektionen und Weichteilkomplikationen. Besonders beim totalen Femurersatz zeigte sich eine erhöhte Reinfektions- und Amputationsrate. Die Kaplan-Meier-Analyse verdeutlichte, dass das Langzeitergebnis durch ein komplexes Zusammenspiel mehrerer Faktoren beeinflusst wird. Insgesamt unterstreicht die Arbeit die hohe Komplexität der septischen Revisionsendoprothetik und die Notwendigkeit optimierter chirurgischer Strategien zur Verbesserung der klinischen Ergebnisse
Structured all-optical domain inversion in iron-doped lithium niobate
No full textRecently, a promising technique for all-optical domain inversion in photovoltaic lithium niobate by visible laser irradiation has been demonstrated. However, only Gaussian light beams have been used to induce the inversion process. Here, we successfully exploit this emergent technique with structured light to fabricate a variety of 2D domain patterns. We use amplitude-modulated continuous-wave visible laser light controlled by a spatial light modulator. Our analysis investigates the relationship between domain growth dynamics and exposure parameters. Domains are evaluated using 3D second-harmonic generation laser scanning microscopy, second-harmonic generation k-spectroscopy, and scanning electron microscopy. The results demonstrate that initial nanodomain growth aligns with crystallographic directions, while the final domain shapes are influenced by both the amplitude of the induction light field and the exposure duration. By controlling light exposure, we create uniform single and multiple spatially shaped domains with lateral extensions ranging from 300 nm to over 400 μm. The correlation between domain formation dynamics and second-harmonic nonlinear diffraction measurements indicates the effectiveness of this structuring method for shaping quasi-phase-matched optical processes
Zwischen Kooperation und Konkurrenz: Vernetzung der Akteur*innen der Wasserstoffindustrie, -politik und -wissenschaft in Deutschland
No full textWelche Netzwerke der Wasserstoffindustrie, der Politik und der Wissenschaft bestehen in Deutschland und welche Bedeutung messen die Beteiligten ihnen bei? Diese Frage stand im Zentrum einer quantitativen Befragung von 170 Stakeholderinnen und Stakeholdern aus der Wasserstoffindustrie, der Politik und der Wissenschaft. Das Arbeitspapier stellt die Ergebnisse dieser Untersuchung vor. Sie zeigen, dass regionale Netzwerke die Landschaft der Wasserstoffbranche in Deutschland prägen. Vernetzung wird vor allem wegen der Möglichkeiten zur Kooperation, zum Wissensaustausch und zur Steigerung der Reputation geschätzt, während praktische Vorteile wie die Personalgewinnung eine nachrangige Rolle spielen. Besonders relevant erscheint die Vernetzung in den Bereichen Infrastruktur, Sicherheit und Regulierung. Die Ergebnisse verdeutlichen, dass Netzwerke zu den zentralen Treibern der Wasserstofftransformation in Deutschland zählen.This study examines how actors from Germany’s hydrogen industry, politics and science are connected through networks and how they perceive their value. Drawing on a quantitative survey of 170 stakeholders, the analysis shows that regional networks dominate the German hydrogen landscape, while strategic initiatives enjoy disproportionate visibility and influence. Overall, membership is perceived as highly beneficial, particularly for cooperation, knowledge exchange and reputation building, whereas more practical benefits such as recruitment or direct problem solving play a minor role. Stakeholders also highlight future networking needs that go beyond technical development, stressing infrastructure, safety, regulatory frameworks and cross-sector integration as crucial fields. The findings suggest that networks are a key driver of the hydrogen transition in Germany, providing platforms for coordination, trust-building and strategic orientation in an emerging market
Co-expression and clinical utility of AR-FL and AR splice variants AR-V3, AR-V7 and AR-V9 in prostate cancer
No full textBackground: Androgen receptor (AR) splice variants (AR-Vs) have been discussed as a biomarker in prostate cancer (PC). However, some reports question the predictive property of AR-Vs. From a mechanistic perspective, the connection between AR full length (AR-FL) and AR-Vs is not fully understood. Here, we aimed to investigate the dependence of AR-FL and AR-V expression levels on AR gene activity. Additionally, we intended to comprehensively analyze presence of AR-FL and three clinically relevant AR-Vs (AR-V3, AR-V7 and AR-V9) in different stages of disease, especially with respect to clinical utility in PC patients undergoing AR targeted agent (ARTA) treatment. Methods: AR-FL and AR-V levels were analyzed in PC and non-PC cell lines upon artificial increase of AR pre-mRNA using either drug treatment or AR gene activation. Furthermore, expression of AR-FL and AR-Vs was determined in PC specimen at distinct stages of disease (primary (n = 10) and metastatic tissues (n = 20), liquid biopsy samples (n = 422), mCRPC liquid biopsy samples of n = 96 patients starting novel treatment). Finally, baseline AR-FL and AR-V status was correlated with clinical outcome in a defined cohort of n = 65 mCRPC patients undergoing ARTA treatment. Results: We revealed rising levels of AR-FL accompanied with appearance and increase of AR-Vs in dependence of elevated AR pre-mRNA levels. We also noticed increase in AR-FL and AR-V levels throughout disease progression. AR-V expression was always associated with high AR-FL levels without any sample being solely AR-V positive. In patients undergoing ARTA treatment, AR-FL did show prognostic, yet not predictive validity. Additionally, we observed a substantial clinical response to ARTA treatment even in AR-V positive patients. Accordingly, multivariate analysis did not demonstrate independent significance of AR-Vs in neither predictive nor prognostic clinical utility. Conclusion: We demonstrate a correlation between AR-FL and AR-V expression during PC progression; with AR-V expression being a side-effect of elevated AR pre-mRNA levels. Clinically, AR-V positivity relies on high levels of AR-FL, making cells still vulnerable to ARTA treatment, as demonstrated by AR-FL and AR-V positive patients responding to ARTA treatment. Thus, AR-FL and AR-V might be considered as a prognostic, yet not predictive biomarker in mCRPC patients
Empirical perspectives on deep learning:from scaling and generalization to new compute paradigms
No full textDie durch neue Rechentechnologien ermöglichte Skalierung künstlicher neuronaler Netze (ANNs) auf nie dagewesene Größen hat nicht nur zu quantitativen Verbesserungen geführt, sondern auch zu qualitativ neuen Phänomenen, die nur bei starker Überparametrisierung zu beobachten sind.
Mit traditionellen theoretischen Ansätzen lassen sich diese großen Modelle nur schwer erfassen.
Um dieses Problem anzugehen, werden in dieser Arbeit empirische Methoden angewandt, um die komplexe, scheinbar chaotische Dynamik großer ANNs zu untersuchen.
Es werden zwei empirische Ansätze vorgestellt, um Generalisierung in ANNs besser zu verstehen und zu verbessern.
Der erste Ansatz untersucht die Breite von Minima in der Loss-Landschaft von ANNs, während der zweite Ansatz die Speicherung einzelner Stichproben durch Vorhersagen zufällig generierter Labels untersucht.
Darüber hinaus haben sich Optische Neuronale Netze (ONNs) als vielversprechende Alternative zu herkömmlichen elektronischen digitalen Rechenarchitekturen herausgestellt.
In dieser Arbeit werden mehrere Strategien für die Implementierung von ONNs vorgeschlagen und es wird erörtert, wie die spezifischen physikalischen Beschränkungen von ONNs aus Sicht der Informatik neue Fragen aufwerfen.Enabled by new computing technologies, the scaling of Artificial Neural Networks (ANNs) to unprecedented sizes has led to more than just quantitative improvements - qualitatively new phenomena have emerged, observable only under heavy overparameterization.
Traditional theoretical approaches struggle to fully capture these large-scale models.
To address this issue, this thesis adopts empirical methods to investigate the complex, seemingly chaotic dynamics of large ANNs.
Two empirical approaches are presented to better understand and improve generalization.
The first approach examines the sharpness of minima in the loss landscape of ANNs, while the second investigates the memorization of individual samples utilizing predictions of randomly generated labels.
Additionally, Optical Neural Networks (ONNs) have emerged as a promising alternative to traditional electronic digital computing architectures.
This thesis proposes several strategies for implementing ONNs and discusses how the specific physical constraints of ONNs raise new questions from a computer science perspective
Energy functionals and symmetry:A cohomogeneity one approach to (poly)harmonic maps
No full textDiese Dissertation untersucht höhere Energie-Funktionale von Abbildungen zwischen Kohomogenität-1 Mannigfaltigkeiten.
Wir beginnen mit der Analyse äquivarianter harmonischer Abbildungen zwischen komplex-projektiven Räumen und finden kontinuierlich parametrisierte Familien von Lösungen. Wir untersuchen die Stabilität dieser Lösungen und deren Grenzkonfiguration.
Anschließend betrachten wir Untermannigfaltigkeiten, die als kritische Punkte höherer Energie-Funktionale auftreten, und konzentrieren uns auf polyharmonische isoparametrische Hopf-Hyperflächen in komplexen Raumformen. In diesem Zusammenhang konstruieren wir eine große Familie von -harmonischen Hyperflächen im positiv gekrümmten Fall und beweisen ein Nichtexistenzresultat für den negativ gekrümmten Fall.
Abschließend entwickeln wir einen systematischen Ansatz zur Konstruktion polyharmonischer Orbits in Kohomogenität-1 Mannigfaltigkeiten. Wir verwenden diesen Ansatz, um Metriken zu finden, welche biharmonische Orbits mit speziellen geometrische Eigenschaften zulassen.This thesis explores higher-order energy functionals within the setting of cohomogeneity-one manifolds, with a focus on understanding the structure and stability of solutions arising from these functionals.
We begin by examining equivariant harmonic maps between complex projective spaces, finding infinite families with uncountably many solutions. We delve into the stability properties of these solutions and examine their limiting configuration.
Following this, we examine submanifolds that emerge as critical points of higher energy functionals. We characterize polyharmonic isoparametric Hopf hypersurfaces in complex space forms. In this context, we identify a large family of -harmonic hypersurfaces in the positively curved case and establish a non-existence result for the negatively curved case.
In the final section, we present a systematic approach for constructing polyharmonic orbits, which allows us to identify metrics that support biharmonic orbits with distinctive geometric properties
