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Memory modules for a cognitive architecture to execute complex manipulation tasks for Personal Service Robots
No full textThis work presents an approach to improving the autonomy of robots. This is done by adding cognitive features with the aim of allowing these robots to be used in homes or care facilities with little supervision. Specifically, my approach is to build knowledge-processing memory modules capable of acquiring, retrieving, storing and updating knowledge. Using modules that simulate memory allows robots to process knowledge and perform better in human environments. In particular, this work focuses on Personal Service Robots executing complex manipulation actions embedded into everyday tasks.
I aim to use techniques of learning from human examples to enable robots to perform everyday tasks in household environments. A human activity recognition system for demonstrations from a Virtual Reality environment was implemented to record and analyze those examples. This system is capable of segmenting trajectories and events into actions and sub-actions. These are stored in a hierarchical data structure called episodes, used by the memory modules to give the robot insight into how to execute such actions.
Also, this research developed knowledge-processing memory modules to extend a cognitive architecture. These memory modules are part of Long Term and Short Term Memory. This architecture is transferable to diverse robotic platforms. It was tested in five robots from different vendors and body configurations. This shows that the knowledge can be used depending on the robot’s necessities and capabilities. The memory modules allow the robot to decide whether and how to adapt actions. This way, the robots can perform complex manipulation actions similar to humans.
The experiments in this work were performed in a simulated kitchen environment. There, the five robots performed actions embedded in the cooking tasks. The results show an improvement in the action execution success by eleven percent and a similar percentage reduction in the time required to perform the tasks.
This work draws inspiration from linguistics, psychology, neuroscience, cognitive science and computer science to create Knowledge Bases. They contain concepts from natural sciences, actions, skills, objects, robotic platform capabilities and experience
Arbeit in der Logistik. Eine regionale Analyse zu den Auswirkungen der Digitalisierung auf Beschäftigungs- und Qualifizierungschancen
No full textMethodological aspects of emulating target trials for causal evaluation of cancer screening programs using health claims data
No full textCancer screening affects cancer-related outcomes by detection at an early – possibly even pre-cancerous – stage, thereby enabling timely treatment initiation or removal of precursors. Ideally, efficacy of cancer screening programs should be assessed in randomized controlled trials before population-wide implementation. In the absence of trial evidence,
or when interest lies in real-world effectiveness, observational data must be used to assess the effectiveness of existing programs. However, limitations of observational study designs and data sources must be addressed.
Issues relating to unclear research questions or incorrect temporal alignment of study
design elements have been identified as a common source of major bias in non-interventional research in recent years. Target trial emulation has been proposed as a framework to formulate clear and precise estimands by defining the study protocol of a hypothetical target trial that would answer the research question at hand and emulating said target trial as best as possible using observational data.
As part of this thesis, I developed a detailed study design for the evaluation of the German mammography screening program regarding its effect on breast cancer-related mortality. Furthermore, I conducted an extensive, realistic simulation study to assess the potential of residual immortal time bias due to the coarse granularity of discrete time available in the underlying database. Next, I emulated a target trial to assess the causal effect of screening colonoscopy on the incidence of colorectal cancer. Differing effectiveness by site of the tumor was reported in previous observational studies on screening colonoscopy. I showed in the present thesis that previous observational studies overestimated the effect of screening colonoscopy and that the difference by site was largely a result of design-induced bias. I extended the initial study design to more complex settings with a sustained no screening strategy and to strategies incorporating the quality of colonoscopy. Finally, I conducted substantive sensitivity analyses tailored to the specific study design and research question, e.g. concerning residual confounding bias, strengthening confidence in the validity of findings
Sartori mud volcano in the Calabrian Accretionary Prism, Mediterranean Sea - Reconstruction of the past ~56 ka of mud extrusion activity
No full textThis cumulative doctoral thesis has been written at the Faculty of Geosciences at the University of Bremen (Germany) and was funded by the Deutsche Forschungsgemeinschaft (DFG). The data analyzed in this PhD have been acquired at the research expeditions M112, POS499, POS515 and SO278 between 2014 and 2020.
The data used in this thesis are all focusing on the morphology, recent activity and eruption history of Sartori mud volcano, located in the Calabrian Accretionary Prism within the central Mediterranean Sea. In seven chapters including three manuscripts, which are either published, submitted or in a draft version, this thesis reconstructs the past ~56 ka of mud extrusion activity of Sartori mud volcano. The analyzes are based on high-resolution multi-parameter studies of geochemical, geophysical and sedimentological data resulting in reconstructions of individual mud eruption phases of the mud volcano
The diatom holobiont in a changing Arctic Ocean
No full textInteractions between diatoms and bacteria are crucial for marine ecosystem functioning and the global climate as they largely govern primary production in marine systems and drive global biogeochemical cycles. Zooming in on the immediate surroundings of a diatom cell, a microhabitat for a diverse and overall mutualistic bacterial community can be found that enables reciprocal exchanges of metabolites benefiting both the diatom and its associated bacteria, which together form a discrete ecological unit – the holobiont. This thesis aims to improve our understanding of how diatom holobionts adapted to occupy Arctic or temperate niches and to which extent diatom-associated bacterial microbiomes help to adapt their host under environmental conditions relevant to climate change and associated climate change-mediated poleward range shifts. The main objectives are to (I) experimentally quantify the response of Arctic and temperate diatoms to abiotic factors that characterize their biogeographic separation and thereby identify potential bottlenecks for adaptation of Arctic diatoms and poleward range shifts of their temperate relatives; (II) determine the net effect of the bacterial microbiome on Arctic and temperate diatom growth under multi-driver settings of these factors to understand its role in host adaptation; (III) unravel how abiotic conditions affect diatom-associated bacterial microbiome community composition and the underlying hostmicrobiome interactions (IV) develop a methodological strategy to understand diatommicrobiome community dynamics on the single- (host-) cell level to enable necessary speciesspecific (in-situ) information of natural diatom microbiomes in the future
Macroscopic and microscopic perspectives on habitat-forming Antarctic hexactinellid sponges
No full textSponges of the class Hexactinellida, commonly known as glass sponges, are conspicuous members of the Antarctic benthos. They grow to considerable sizes and can form dense aggregations on the continental shelf of the Southern Ocean. These sponge grounds are associated with a high biodiversity as the large barrel-shaped hexactinellid sponges provide a complex three-dimensional structure and various micro-habitats for other animals. Their role as habitat-forming species has been well established, but other aspects of their biology remain largely unexplored. This thesis investigates Antarctic hexactinellid sponges from different perspectives that have previously been understudied or neglected. It presents new insights on their in-situ identification, their microbiomes, and their relevance for pelagic top predators.
Ecological studies on Antarctic benthos regularly use seafloor imaging for in-situ observations of habitats and communities. However, in-situ species identification of Antarctic hexactinellid sponges has often been problematic due to unprecise species descriptions focusing on microscopic skeletal spicules while disregarding external macroscopic features, as well as several taxonomic changes. Therefore, the first objective of this thesis was to develop a practical and reliable macroscopic approach to image-based species identification of the common hexactinellid sponges of the Antarctic shelf, comprising Anoxycalyx (Scolymastra) joubini and eight currently accepted species of the genus Rossella.
In order to identify diagnostic macroscopic characteristics of each species, I combined the examination of trawl-collected sponges, previous species descriptions, and a large collection of in-situ photographs and videos. Manuscript I describes all aspects of the external morphology of each species, accounting for their morphological variability and identifying species-specific characteristics. Special emphasis is put on the differentiation of species that have been mixed up in the past. The manuscript shows that each species in fact has unique macroscopic features that can be used to distinguish them in situ and without expert taxonomic knowledge. This provides a basis for species-specific observations on Antarctic hexactinellids in image-based studies.
The second objective of this thesis was to elucidate the role of Antarctic hexactinellid sponges as habitat on different scales beyond the direct macroscopic associations. Therefore, I investigated them from a microscopical perspective and from a top predator’s perspective. It is well known that sponges can host a variety of symbiotic microorganisms in their tissue. The sponge-associated microbial communities are species-specific and tightly coupled with their host regarding metabolic processes, chemical defense, and health. However, the microbial associations of Antarctic hexactinellids have barely been investigated before. Even less explored is the relevance of hexactinellid sponges for pelagic megafauna like seals or other top predators, despite descriptions of various fish species using them as habitat and nursery ground.
In order to describe the microbiomes of Antarctic hexactinellids and to compare them to those of Antarctic demosponges and deep-sea sponges from other regions, I have sampled deep-water hexactinellid and demosponge specimens for inclusion in two studies. Their microbial communities were analyzed by 16S rRNA gene sequencing and generation of amplicon sequence variants (ASVs). In addition, histological and ultrastructural analyses were conducted for several sponges. Manuscript II provides a detailed description of the microbiomes of Antarctic hexactinellids and demosponges in relation to sponge histology. All sponges were characterized as low microbial abundance sponges, but the denser the sponge tissue, the higher was the number of hosted microbes. Furthermore, the microbial community composition in hexactinellids and demosponges was significantly different. Although the hexactinellids showed a lower microbial richness than the demosponges, their microbiome comprised a higher percentage of class-specific ASVs. Manuscript III integrates these findings into a global analysis of deep-water sponge microbiomes. It shows that hexactinellid sponges in general have a characteristic microbiome distinct from that of demosponges. Compared to sponges from other regions, the Antarctic hexactinellids were among the species with the lowest microbial richness. Taken together, both studies show that Antarctic hexactinellid sponges host unique microbial communities.
Scaling up to a wider ecosystem context, Manuscript IV describes a previously unknown interaction of Weddell seals with Antarctic hexactinellid sponges. In a study on the foraging behavior of female Weddell seals during lactation period using animal-borne video recorders, several seals were found to investigate the cavities of large hexactinellid sponges, presumably searching for prey. This behavior was observed for the first time and it is currently unknown how widespread it is. All sponges in the videos were identified as Rossella cf. racovitzae, but other hexactinellid species may likewise serve as foraging ground for seals.
Overall, this thesis shows that the role of Antarctic hexactinellid sponges as habitat extends beyond the well-described associations of benthic fauna and that their relations with other organisms are more complex and diverse than previously recognized. They also host specific microbial communities and are relevant as foraging habitat for Antarctic top predators. Both aspects require further dedicated research to elucidate their ecological implications. As demonstrated in this thesis, changing perspectives may help to further broaden our understanding of the various roles of hexactinellid sponges in Antarctic marine ecosystems
Actionable Knowledge Graphs - how daily activity applications can benefit from embodied web knowledge
No full textThis Thesis proposes a five-step methodology for creating actionable knowledge graphs that follows existing knowledge engineering standards but links object knowledge to environment and action knowledge to enable various applications in daily environments, on different agents. The methodology is exemplary applied in two scenarios with different foci to create a product knowledge graph and a food cutting knowledge graph. The product knowledge graph aims at enabling omni-channel applications in unknown environments. It therefore contains product-related knowledge that is used by different agents such as smartphone, smart glass and robot, which aim at providing shopping assistance in a retail store. In order to provide user assistance like routing a customer to a searched product on different devices such as robot or smartphone, this scenario focuses on accessing relevant Web knowledge about products in a retail store that is linked to precise, reliable and agent-independent environment information. The food cutting knowledge graph aims at enabling robots to execute task variations of cutting actions. Here, the idea is to access Web knowledge to enable a robot to autonomously perform a range of cutting tasks. Therefore, this scenario focuses on how object information can influence action execution, how the needed knowledge can be acquired from the Web and how it can be modelled in a knowledge graph in such a way that a robot can use it to execute tasks. The methodology is validated by showcasing various applications that are enabled by the two exemplary knowledge graphs. The applications range from smartphone applications for shopping assistance that highlight interesting product features or route to a searched product over smart glass applications like shopping assistance and a recipe application to robot applications for shopping assistance and execution of cutting task variations on different fruits and vegetables
Immersive Medical VR Training Simulators with Haptic Feedback
No full textVirtuelle Realität und haptisches Feedback sind Technologien, die die medizinischen Ausbildung, insbesondere in den Bereichen der Orthopädie und Zahnmedizin, revolutionieren werden. Diese neuartigen Technologien ermöglichen die Erschaffung virtueller Trainingssimulatoren, welche eine risikofreie Umgebung zu der Verbesserung der Fähigkeiten von medizinische Auszubildende. Damit präsentieren solche Simulatoren eine Lösung für die ethischen Dilemmas, die häufig mit patientenbasierten Ausbildungsmethoden verbunden sind. Die Herausforderung besteht jedoch darin, Simulatoren zu entwickeln, die nicht nur immersiv, sondern auch realistisch und effektiv in der Übertragung von gelernten Fähigkeiten von virtuellen auf reale Szenarien sind.
Diese Dissertation präsentiert ein bahnbrechendes modulares System für VR-basierte Physiksimulation mit haptischem Feedback, das entwickelt wurde, um diesen Herausforderungen zu begegnen. Es integriert kontinuierliche, realistische Kraftrückkopplung mit sechs Freiheitsgraden und Materialabtrag, welche eine authentische Interaktion mit virtuellen anatomischen Strukturen und Werkzeugen gewährleistet. Zentral für dieses System sind neuartige Algorithmen für Kollisionserkennung, Kraftrendering und eine volumetrische Darstellung, welche gemeinsam den Realismus und die Leistung von VR-haptischen Simulatoren auf ein beispielloses Niveau verhelfen. Diese Algorithmen wurden in eine Bibliothek implementiert, welche im Zusammenhang mit einer Vielzahl von Game-Engines, Haptikgeräten und virtuellen Werkzeugen verwendet werden kann.
Praktische Anwendungen dieser neuartigen Simulationsbibliothek wurden durch die Entwicklung von zwei modernen medizinischen Ausbildungssimulatoren demonstriert: einem für die totale Hüftendoprothese und einem anderen für zahnmedizinische Eingriffe, mit Fokus auf Wurzelbehandlung und Kariesentfernung. Diese Simulatoren werden durch weitere innovative Funktionen, wie automatischer VR-Registrierung, Klangsynthese basierend auf Materialentfernung, VR-Zoom und genauem Eye-Tracking, verbessert. Diese Zusatzfunktionen tragen zu einem noch immersiveren Trainingserlebnis bei. Bei rigorosen Tests haben diese Simulatoren einen signifikanten Lerneffekt gezeigt, der es den Studenten ermöglicht, die in einer virtuellen Umgebung erlernten Fähigkeiten nahtlos auf reale medizinische Verfahren zu übertragen.
Der Hüftchirurgiesimulator wurden von 18 Orthopäden erprobt, welche das System im aktuellen Zustand kollektiv als bereits nützlich bewerten. Außerdem gaben die Experten an, dass sie es Medizinstudenten und sogar Assistenzärzten empfehlen mit dem Simulator zu üben. Der Zahnmedizinsimulator wurde innerhalb von zwei Experimenten mit einer größeren Anzahl von Zahnmedizinstudenten (40 und 30) evaluiert. Die tatsächlichen Fähigkeiten der Zahnmedizinstudenten wurden dafür vor und nach dem Training durch unabhängige Experten beurteilt. Die Datenauswertung hat ergeben, dass eine signifikanter Lernfortschritt, gemessen an tatsächlichen Fähigkeiten, festgestellt wurde, welcher auf das Training mit meinem VR-Simulator zurückzuführen ist. Das erste Experiment lieferte außerdem aufschlussreiche Daten darüber, wie spezifische technologische Aspekte von VR in Head-Mounted Displays die Lerneffektivität und die Übertragbarkeit der Ausbildung beeinflussen. Meine Ergebnisse zeigen, dass die Überlagerung von realen und virtuellen Werkzeugen, sowie Stereoskopie, entscheidend dafür sind, um den Lerneffekt und die Nutzbarkeit von VR-Simulatoren zu verbessern. Darüber hinaus hat das zweite Experiment neue Perspektiven auf das Trainingsverhalten von Zahnmedizinstudenten eröffnet, insbesondere in Bezug auf die Nutzung von indirekter Sicht und deren Zusammenhang mit Leistung und Lerneffektivität. Diese Erkenntnisse wurden auch ermöglicht, durch die Konzeption von neuartigen Metriken für indirekte Sicht in komplexen, beidhändigen Tätigkeiten.
Durch das Erweitern der Möglichkeiten von VR- und haptischer Technologie in der medizinischen Ausbildung leistet diese Dissertation einen bedeutenden Beitrag zum Forschungsfeld und bietet fortschrittliche Werkzeuge, die ermöglichen, die Art und Weise, wie medizinische Fachkräfte ausgebildet werden, zu revolutionieren.
Die entwickelten Simulatoren machen die Ausbildung nicht nur effizienter und effektiver, sondern eröffnen auch neue Forschungsfelder in der medizinischen Bildung, mit dem letztendlichen Ziel, die Patientenversorgung und Behandlungsergebnisse zu verbessern
Die Moschee in der Schule. Kompetenzförderung durch Entdeckendes Lernen - eine Moscheeerkundung in der Grundschule
No full textDie Moschee für Schüler*innen?! Diese Monographie bietet Vorschläge für den
kompetenzorientierten Unterricht mit Fokus auf eine Moscheeerkundung und reflektiert die Moschee als Lernort für Schüler:innen. Im Rahmen des Religionsunterrichts ist der Besuch von Sakralräumen besonders relevant. In den letzten Jahrzehnten wurden didaktische Ansätze für Sakralbauten vor allem für Kirchen erarbeitet. Die Erschließung von Sakralbauten außerhalb christlicher Traditionen ist hingegen unterrepräsentiert.
Durch die Verbindung von didaktischer Theorie mit religionsunterrichtlicher Anwendung und deren Beforschung im Kontext des Bremer Religionsunterrichts wird der grundlegenden Frage nachgegangen, inwiefern die Moschee als außerschulischer Lernort in den Unterricht integriert werden kann. Für die Konzeption einer entsprechenden Unterrichtseinheit, die den Besuch einer Moschee rahmt, werden kirchenraumpädagogische Überlegungen mit allgemeindidaktischer Forschung verknüpft. Dabei fließen Erkenntnisse zu den Zieltaxanomien nach Benjamin Bloom, den
Choreographien des Unterrichts nach Fritz Oser sowie Überlegungen zu Betrachtungsweisen von Moscheen, die diese als multifunktionale Versammlungsorte verstehen, ein.
Anhand dieser vielschichtigen Perspektiven auf Moscheen wird nicht nur eine Unterrichtseinheit zum Entdeckenden Lernen dargelegt, sondern zudem Vorschläge für Moscheeerkundungen eröffnet und somit didaktisches Material zur kompetenzorientierten Gestaltung des überkonfessionellen Religionsunterrichts in der Grundschule angeboten.13
Spatial heterogeneity and seasonal evolution of surface properties and radiative fluxes of Arctic sea ice
No full textIn recent years, the Arctic sea ice has experienced a significant decline, characterised by the smaller extent, longer melt season, and a shift from thick multi-year ice to thinner first-year ice. As a result, more solar radiative energy is deposited into the Arctic sea ice and the ocean underneath, further enhancing sea ice melt and ocean heat. When the Arctic is transitioning from melt onset to freeze onset, the sea ice surface spatial variability becomes stronger, altering the spatial distribution of radiative energy deposition. Understanding the seasonal evolution and spatial variability of solar radiative fluxes is a key step to broadening our knowledge of the changing Arctic sea ice.
In this thesis, I investigate the year-round changes in solar radiative fluxes within the Arctic sea ice, both temporally and spatially. I examine the changes in optical properties during the Multidisciplinary drifting Observatory for the Study of Arctic Climate expedition (MOSAiC) in 2020. This thesis utilises a wide range of sensors and platforms, ranging from long-term continuous point measurement, to weekly under-ice mapping of light field, and to ice-floe size parameterization. This thesis highlights the spatial variability of the solar radiative fluxes of Arctic sea ice: under the same atmospheric condition and located on the same ice floe, different locations show highly variable evolution. The largest variability is in the middle of the melt season, due to the changing melt pond coverage and status. The sea ice types and surface conditions are crucial for the sea ice energy budget, thus further controlling the melting process.
This thesis provides a comprehensive 3-dimensional view of the sea ice radiative fluxes and improves the parameterization of sea ice optical properties. Also, by investigating the effects of spatial surface variability, which is a function of time and area, this thesis guides future observations of the new Arctic sea ice regime. This study bridges in-situ observation to floe-size parameterisation, advances our understanding of the upscaling of solar radiative energy fluxes both onto and through the Arctic sea ice, and deepens our understanding of the impact of sea ice heterogeneity on the large-scale energy budget of the melting Arctic sea ice