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The fate of fucoidan in the ocean
No full textRising carbon dioxide levels and the goals of the Paris Agreement have intensified the focus on carbon removal strategies. Blue carbon ecosystems, including mangroves, salt marshes, seagrass meadows and macroalgae are key to carbon sequestration due to their ability to store large amounts of carbon in their biomass. Unlike rooted plants, algae release dissolved organic carbon over their mucilage layer, with up to 50% of brown algae exudates consisting of fucoidan, a complex polysaccharide.
This thesis confirms the active release of fucoidan by six brown algae species. Globally, up to 0.1 Gt of fucoidan carbon is exuded annually, equivalent to 0.367 Gt of carbon dioxide. Fucoidan resists microbial degradation, aggregates and is transported to and stored inside coastal ecosystems. This research highlights the collective storage of
carbon by coastal vegetated ecosystems and emphasises that algal-derived polysaccharides are promising candidates for carbon sequestration
Digital Transformation Mindset - Haltungswandel als Kern des digitalen Zeitalters
No full textWährend das Konzept des Digital Mindset in der Literatur bereits Aufmerksamkeit gefunden hat, bleibt die Frage, wie Menschen und Organisationen digitale Transformation als dynamischen Prozess erleben und gestalten können, bislang weitgehend unbeantwortet. Diese Studie führt den Begriff des Digital Transformation Mindset (DTM) ein – verstanden als Haltung, die es ermöglicht, kontinuierlich auf technologische Veränderungen zu reagieren, tiefgreifende Einsichten (Insights) zu gewinnen und Transformation aktiv mitzugestalten. Auf Basis qualitativer Interviews und Beobachtungen auf dem Camino de Santiago sowie begleitender Workshops mit Führungskräften und Studierenden wird gezeigt, dass Transformation auf fünf miteinander verflochtenen Ebenen verläuft: Struktur, Transformation, Emotion, Wahrnehmung und Kognition. Besonders hervor tritt die Rolle von Aha-Momenten, die im Zusammenspiel von Wahrnehmungen und Emotionen entstehen und kognitive Durchbrüche ermöglichen. Aufbauend auf diesen Ergebnissen formuliert die Studie Handlungsempfehlungen auf individueller und organisationaler Ebene, die zeigen, wie ein Digital Transformation Mindset nicht nur entwickelt, sondern auch langfristig in Organisationen verankert werden kann – als Schlüssel, um die digitale Zukunft aktiv zu gestalten
Modular task modeling and creation of high-level building blocks for implementing complex robot applications
No full textComponent-based frameworks for the development of robot control software provide tools to support software development and define a common component interface for the software created in this framework. This has a significant impact on robot programming: while the tools increase developer productivity, the common component interface increases software reusability. As a result, roboticists can now benefit from an extensive collection of software components.
In a component-based software framework, the robot's behavior is defined by the selection of individual components, their configuration and the connections between the components. The reuse of software components significantly reduces development work, particularly in the development of general algorithms. For robot systems that have to be able to handle a wide range of applications with numerous behaviors and algorithmic approaches, current software frameworks lack the flexibility to ensure the necessary variability in robot control, which hinders the realization of versatile robot systems.
Model-driven software development enables the realization of development processes in which recurring development tasks are automated through model transformation pipelines. The use of domain-specific languages makes it possible to design complex software systems in a more efficient and accessible way.
This work investigates methods for the model-driven development of robot controllers. The focus is on the specification and execution of modular robot applications that combine a variety of different control paradigms and algorithms and can be adapted to different robot systems or application scenarios.
A software ecosystem is presented, consisting of (a) a software system for modeling and executing robot controllers that are freely reconfigurable and interchangeable at the robot's runtime, (b) a high-level task modeling and execution environment that allows the integration of multiple behavior description paradigms into a common framework, and (c) a meta-modeling environment for creating high-level integration building blocks that can be adapted to different robot systems or tasks.
After an introduction to the general research area and the technological foundations, the individual proposed technologies are presented. The underlying model representations and domain-specific languages are explained and the implementation of the software systems based on them is presented. Each software system is evaluated and discussed individually, whereby practical validation tests with real robot systems, dedicated performance measurements and theoretical considerations regarding the limits and performance of the software are made The evaluation confirms the applicability of the software for the intended application area of reconfigurable robot controllers and for the integration of complex control systems. In addition, open issues are identified and extensions of the proposed software are discussed for possible future work
Synthesis and characterization of ɣ-, β-, and δ-phases of bismuth oxide
No full textDie Polymorphie von Bi2O3 ist thermisch getrieben, wobei die Hochtemperatur δ-Phase die vielversprechendste für die Verwendung als Festoxid-Elektrolyt in der Brennstoffzellentechnologie darstellt. Das Hauptziel dieser Arbeit ist es, die δ-Phase bei Umgebungsbedingungen zu stabilisieren, indem Bi3+ durch andere Kationen ersetzt wird. Diese Dissertation konzentriert sich auf die Synthese verschiedener Bi3+-substituierter Serien und die Untersuchung der strukturellen Beziehungen zwischen den Phasen, mit besonderem Augenmerk auf die Unordnung in der δ-Phase.
Der Effekt von anionischen und kationischen Fehlstellen sowie dem einsamen Elektronenpaar von Bi3+ auf strukturelle Modifikationen wird durch den Austausch von Bi3+ mit In3+-Kationen (Kapitel 3) [1] untersucht. Eine Reihe von Sillenit-Verbindungen mit der Formel Bi12(Bi3+4/5-3xIn3+5x□1/5-2x)O19.2+3x□0.8-3x (x = 0,03 - 0,27) wird synthetisiert, um zu verstehen, wie sich die In3+-Substitution auf die Eigenschaften des Materials auswirkt. Die Festkörpersynthese wird verwendet, und die Proben werden durch Röntgenbeugung (XRD), Raman-Spektroskopie, UV/Vis diffuse Reflexion und thermogravimetrische Analyse charakterisiert. Die Röntgenpulverdaten zeigen, dass für x = 0,03 - 0,08 phasenreine Proben erhalten werden, während In2O3 für x > 0,08 als Nebenphase erscheint. Der Gitterparameter verringert sich mit zunehmender In3+ Konzentration, was darauf hinweist, dass die kleineren In3+ Kationen Bi3+ ersetzen. Die einsamen Elektronenpaare von Bi3+ und Kationen-Fehlstellen verändern die Bindungslängen und Raman-Spektren zeigen eine Phononenverhärtung bei reduzierten Fehlstellen. Die Bandlücke nimmt mit steigendem In-Gehalt zu, und zusätzliche Absorptionsbänder werden für x = 0,03 - 0,08 beobachtet. Stärkere In-O Bindungen verbessern die thermische Stabilität, was durch thermogravimetrische Daten bestätigt wird. Der Austausch von Bi3+ mit Lanthanoid-Kationen (Kapitel 4) eignet sich für die Bildung der δ-Phase bei verschiedenen Substitutionslevel, wobei die Bildung vom Kationenradius abhängt. Es wird eine Serie hochsymmetrischer δ-(Bi1-xMx)2O3-Phasen, mit M = Y, Gd, Tb, Dy, Ho, Er, Tm, Yb und Lu, mittels der Festkörpersynthesemethode synthetisiert, dabei reicht x von 0,05 bis 0,25. Rietveld-Verfeinerungen der Röntgenbeugungsdaten werden verwendet, um jede Probe zu charakterisieren. Die Art des M3+-Kations und die Zusammensetzung (x) beeinflussen erheblich die Transformation von der niedrigsymmetrischen β-Phase zur hochsymmetrischen δ-Phase. Der Austausch von Bi3+ durch kleinere M3+-Kationen verringert den Gitterparameter. Raman-Spektren bestätigen das Vorhandensein der δ-Phase und zeigen charakteristische Merkmale wie Bandverbreiterung und Blauverschiebungen. Die direkte Bandlücke erreicht 2,75(4) eV, mit zusätzlichen Absorptionsbändern, die auf anionische Defekte hinweisen. Die thermische Stabilität wird durch Veränderungen der Bi/M–O-Bindungsstärke erklärt, wobei ein endothermer Peak auf Ordnungs-Unordnungs-Übergänge in der δ-Phase hinweist. Die komplexen strukturellen Modifikationen in der δ-Phase werden weiter untersucht, indem Bi3+ mit Cr3+ und Ta5+-Kationen (Kapitel 5) substituiert wird. Zwei Serien werden untersucht: die Cr-Serie (x = 0,15 bis 0,30) und die Ta-Serie (x = 0,05 bis 0,30). Während der Synthese bei 1273 K wird Cr3+ zu Cr6+ oxidiert, was zu einem gemischten Oxidationszustand führt, der durch Röntgenphotoelektronenspektroskopie identifiziert wird. Die Cr-Serie zeigt eine stabile δ-Phase mit konstantem Gitterparameter, während die Ta-Serie mit zunehmendem x von der β-Phase zur δ-Phase übergeht. Raman-Spektroskopie und Rietveld-verfeinerte Röntgenbeugungsdaten bestätigen die Phasen. Die Bandlückenenergie beträgt 2,27(2) eV für die Cr-Serie und 2,93(2) eV für die Ta-Serie bei x = 0,25. Defektbezogene Absorptionsbänder zeigen Sauerstofffehlstellen in beiden Serien und bestätigen damit die strukturellen Modifikationen in der δ-Phase
Leitfaden zur Umsetzung der kommunalen Wärmeplanung für BürgerInnen
No full textDas Forschungsprojekt „KoWaP-Pro“ untersucht ordnungsrechtliche, prozessbezogene und maßnahmenbezogene Ansätze für die Umsetzungsphase der Wärmepläne. Das Projekt wird durch das 7. Energieforschungsprogramm des BMWE gefördert. Im Rahmen des Projekts sind zahlreiche Publikationen zu ausgewählten Aspekten der Umsetzung der kommunalen Wärmeplanung entstanden. Dieser Leitfaden ist einer von drei akteursspezifischen Leitfäden zur Umsetzung der kommunalen Wärmeplanung, die für Kommunen, Energieversorgungsunternehmen und BürgerInnen erstellt wurden
Ecophysiology of Red Sea Corals in Response to Carbon and Nitrogen Availabilities
No full textCarbon (C) and nitrogen (N) are essential for coral health, growth and energy production. Yet, maintaining a balanced availability of these elements is critical, as both deficiencies and excesses can have negative consequences for coral survival. This thesis explores how key Red Sea coral taxa, including reef-forming hard corals and a dominant soft coral species, respond to C and N availability, providing insights into their ecophysiology and resilience to environmental challenges such as nutrient pollution. Research Question 1 explored the ecophysiological responses of Red Sea corals to natural C fluxes, as detailed in Chapters 2 and 4. Chapter 2 showed that Xenia umbellata’s physiology was negatively impacted by the absence of heterotrophic food, reducing pulsation rates, symbiont density, and mitotic index, though the coral compensated by increasing symbiont chlorophyll-a content. Water flow had no significant effect, likely due to its pulsation-driven flow regulation. Chapter 4 revealed that azooxanthellate corals like Tubastraea coccinea exhibited significantly higher denitrification rates than zooxanthellate species, as denitrifiers utilised environmental C (e.g., DOC), instead of relying solely on photosynthates. High DOC availability (in addition to other environmental and physiological factors) was identified as one of the key drivers of denitrification in Acropora spp., Millepora dichotoma and Tubastrea coccinea, highlighting the role of C in N cycling processes in corals. These findings emphasise the critical role of both autotrophic and heterotrophic strategies in corals' responses to natural variations in C availability and its influence on biogeochemical processes like denitrification. Research Question 2 investigated the ecophysiological responses of Xenia umbellata to excess C availability under eutrophic conditions, as explored in Chapter 3. The study found that excess organic matter (OM) at 20 mg C L-1, provided as dissolved organic matter (DOM) had no negative effect on coral ecophysiology. However, particulate organic matter (POM) in the form of phytoplankton and zooplankton, caused significant damage, including impaired feeding tentacles, reduced pulsation rates, and increased mortality. The severity of these effects was primarily linked to POM dosage, rather than particle size, highlighting X. umbellata’s vulnerability to coastal eutrophication, where excess POM can harm its ecophysiology. Research Question 3 explored the ecophysiological responses of Red Sea corals to natural fluctuations in N availability, addressed in Chapter 4. High ammonium levels drive denitrification in Acropora spp., as ammonium supports nitrification and nitrate production, a key substrate for denitrifying bacteria. Unexpectedly, T. coccinea showed elevated denitrification under low nitrate availability, likely due to co-occurring N2 fixation and denitrification, characteristic of oligotrophic Red Sea conditions. These results emphasize that coral responses to N fluxes are highly species-specific and influenced by local nutrient dynamics, underscoring the need to consider both biological and environmental variability when assessing coral reef resilience. This thesis highlights Xenia umbellata’s adaptability to low C availability and variable flow but reveals its vulnerability to excess C inputs, exposing soft corals to anthropogenic threats. Species with higher heterotrophic capacities may better withstand inorganic N pollution, potentially driving shifts toward heterotrophic-dominated reefs with significant biodiversity and ecosystem implications. This thesis offers critical insights into the physiological responses of Red Sea corals to ambient and excess nutrient levels, helping to predict reef resilience and shifts in community composition. The findings provide a basis for targeted management strategies to mitigate nutrient-related stress, especially in light of expanding coastal development projects in the Central Red Sea region
Preparing and documenting ethnographic data for archiving and subsequent use - an overview for researchers
No full textThis working paper is aimed at social and cultural anthropologists, and ethnologists but also at researchers from other disciplines who work with ethnographic approaches. It provides information on the possibilities of making research data accessible for further use at the Qualiservice Research Data Center and outlines the necessary preparatory steps.QS-WP-8-202
The impact of low-frequency anthropogenic noise on macroinvertebrates of the North Sea
No full textAnthropogenic underwater noise is by no means a novel pollutant and with the ever-increasing volume of marine traffic as well as other offshore human activities such as wind energy and natural resource extraction, the oceanic ambient sound levels are set to continue rising. While research on anthropogenic noise effects on marine mammals and fish spans over half a century, similar research for marine invertebrates has only started gaining traction in the last one to two decades. Consequently, marine invertebrates remain critically understudied in this regard. These organisms are crucial ecosystem components due to their roles in influencing sediment dynamics, benthic production, and constituting key prey for higher trophic levels among others. The few published studies to date highlight that anthropogenic noise can negatively affect invertebrate behavior as well as physiology. Considering the multitude of vital roles invertebrates play in their respective ecosystems and the continuously rising sound levels in the ocean, more exploratory research is urgently needed.
This thesis investigated the effect of anthropogenic, continuous low-frequency noise (CLFN) on invertebrate model systems from different benthic communities typical of the North Atlantic coasts. The overarching objective was addressed through five controlled laboratory experiments, each examining the potential implications of CLFN within a distinct biotope. These implications were explored through the effects of CLFN on key behaviors and/or physiological parameters involved in model systems from respective benthic communities. Experimental findings were put into context by quantifying the sound levels and vessel prevalences of a typical nearshore environment in which the different communities may be found.
Infaunal communities are composed of invertebrates that live within the seafloor sediment. These invertebrates continuously disrupt the sediment they inhabit through activities such as burrowing and ventilating and thereby influence local sediment dynamics and biogeochemistry. Chapter 2 & 3 investigated how CLFN affects the sediment reworking and bioirrigation activities of four macrobenthic invertebrates. Chapter 2 demonstrated that added noise reduced burrowing by the amphipod crustacean Corophium volutator. The bivalve Macoma balthica exhibited a potential stress response while the polychaete Arenicola marina showed greater variability in irrigation rates. Chapter 3 further revealed that added noise reduced the ventilation (and thus, bioirrigation) rate and disrupted the ventilation pattern of the polychaete Lanice conchilega. These findings demonstrate how bioturbation, a crucial benthic process, can be impacted by anthropogenic noise. If sustained, outward-rippling effects on the local sediment dynamics and biogeochemistry may be possible.
Mesograzing communities are characterized by small, herbivorous invertebrates that live among and graze on macrophyte assemblages. Not only do these mesograzers control macrophyte growth and assemblage structure through their grazing, but they also facilitate the transfer of primary production. Chapter 4 investigated how CLFN affected the metabolism and energy pathways of two crustacean mesograzers. The amphipod Gammarus locusta exhibited greatly reduced oxygen consumption rates with no changes in metabolic enzyme activities while the isopod Idotea balthica appeared robust to CLFN in these aspects. Chapter 5 further investigated how CLFN affected the feeding performance and habitat choice as well as the metabolism and energy pathways of the amphipod Marinogammarus marinus. Added noise reduced feeding rate and overall consumption of algal material and elevated the activity of an enzyme often used to estimate respiratory rate, suggesting increased oxygen consumption and metabolism. These findings indicate the potential interference of CLFN with processes integral to the top-down control of macrophyte growth by mesograzers, which may result in ecosystem-wide shifts such as community restructuring depending on effect severity.
Mussel bed communities are formed when mussels aggregate using byssal threads on hard substrate. These beds provide biogenic substrate for other organisms, thereby constituting biodiversity hotspots to the neighboring communities. Chapter 6 investigated how CLFN, as well as the interactive effect of noise and predator cues, affect the byssal thread production of blue mussels of the Mytilus edulis complex. Mytilus produced more threads in the presence of predator cues, but were ostensibly robust against CLFN in this aspect. This might explain how blue mussels so successfully colonize inherently disturbed habitats such as artificial hard substrates, indicating their continued persistence as well as expansion with offshore man-made structures.
The North Sea island of Helgoland, a nature reserve rich in marine biodiversity, is surrounded by human activity. Documenting and analyzing the local sound levels are thus pivotal for marine conservation management in evaluating the anthropogenic impacts in this ecologically significant region. Chapter 7 investigated the ambient sound pressure levels and the contribution of vessels near Helgoland by deploying a hydrophone for more than a year. Overall, the surveyed site was quieter than other sites documented across the North Sea. Of the months analyzed, vessel events occurred at prevalences of up to 18% and raised the ambient sound levels by an estimated mean of 5.5 dB (4.6 dB median). The very shallow depths, however, compromise sound propagation, which meant that vessel noise from the nearby shipping lane was likely already fairly attenuated upon reaching the recorder. Sound levels inside the shipping lane are expected to be much higher during events and the impacts on fauna more severe. Given that the experimental noise treatments used in this thesis were quieter than vessels typical of the area based on source levels, the results of the experiments described in Chapters 2-6 possibly even underestimate the potential impacts found directly inside shipping lanes.
This thesis demonstrates how CLFN impacts different benthic biotopes through its effects on behaviors that drive essential ecosystem processes, as well as on physiological parameters integral to the homeostasis of the invertebrates performing these behaviors. The findings underscore the importance of understanding the influence of noise on entire ecosystems and not only on the organism-level. This thesis also indicates that the impact of anthropogenic CLFN in very shallow systems typical of continental shelf regions may be more localized than that in the open ocean, accentuating the need for effect testing across a gradient of sound levels. These considerations will be essential for predicting realistic impacts of noise pollution on our changing oceans moving forward
On the concept of communication in the face of artificial conversational agents
No full textThere are, as of course well known in the philosophy of communication, several conceptualisations of the phenomenon of communication throughout media and communications research. Examples include the intersubjective sharing of experience, or intersubjective sharing of understanding, and many conceptualisations boil down to James Careys oft-cited distinction between a ritual and a transmission approach to communication. Many, if not most, of these conceptualisations presuppose two “morally autonomous selves”, as John Durham Peters has pointed out. With the rapid spread of Communicative AI (ComAI), this perception needs to be re-evaluated. Much mediated conversation today occurs, not between humans, but between humans and machines, and there is a rapidly growing body of research that suggests new ways of conceptualising these communicative relations. Still, most communication theory suggest the social to be an important ingredient in communication. The paper will discuss some social situations in which ComAI has been implemented, and the implications this might have for our understanding of the concept of communication.4
Multiphase numerical modeling and investigation of heat transfer during quenching of metallic specimen by means of water jets
No full textThe necessity of advanced efficient materials for engineering applications such as structural, aerospace, automotive etc., is expanding. To improve the usage characteristics for instance hardness, strength, heat treatment utilizing the water jet quenching process has been conventionally adopted by metal industries. To achieve this, metal plates are heated and rapidly cooled with water jets or array of jets. During this process, the spatial and temporal thermal history in the material based on the process control parameters determines the resulting material properties of the metal plate. Since the metal plate is quenched from a very high surface temperature, this creates immense temperature gradients within the plate, which may lead to distortion and even cracking. In addition, for applications such as direct chill casting and hot rolling, the metal plate traverses under the water jets, escalating the process complexity. Due to the Leidenfrost effect, the challenge is to establish a controlled heat transfer where the water contacts with the hot surface (wetting), which is particularly hindered by the strong vapor generation at the hot surface. The heat transfer is dominated by boiling heat transfer (film, transient, nucleate boiling). Therefore, a thorough investigation of the spatial and temporal heat transfer of this conjugate heat transfer process is necessary to identify the relevant process control parameters. In this thesis, the quenching of a hot metal plate with circular water jets (full jet) is investigated for stationary as well as moving plates. The impact of the nozzle arrangement in groups or fields with the configurations such as inline and staggered on boiling heat transfer is analyzed for stationary plate quenching. The plate materials investigated are aluminum alloy (AA6082) and stainless steel (1.4828), where the quenching fluid is normal tap water at room temperature. To address this conjugate heat transfer problem, a two-phase numerical model based on the Euler-Euler approach has been developed to simulate the full quenching of both the stationary and the moving metal plate, where water acts as a continuous phase and the water vapor as a dispersed phase. To model the phase transfer during quenching (water/water vapor), the source and sink terms of the corresponding conservation equations for mass, momentum and energy are modified accordingly. The model for the translational motion of the metal plate has been realized by adopting the concept of a sliding mesh. Experiments are performed to validate the developed numerical models in a two-way approach by means of high-speed and infrared imaging considering the hydrodynamic and thermodynamic perspectives. This validated numerical model can provide the relevant hydrodynamic and thermodynamic engineering parameters directly from the impinging side of the plate such as wetting front propagation, heat flux, HTC (heat transfer coefficient), cooling curve etc., which cannot be easily obtained from conventional experiments. The influence of process control parameters on the boiling heat transfer during quenching is analyzed numerically by varying the jet Reynolds number, plate velocity, plate material, plate thickness, plate initial temperature and subcooling, providing a detailed insight into the hydrodynamic and thermodynamic behavior during the jet quenching of a metal plate in the heat treatment process