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Education policy in Senegal: global transformation processes, IOs’ influence and cultural spheres
No full textThis paper gives a historical perspective of the Senegalese education system and how different global transformations, namely French colonization, the impact of Islam as a cultural sphere and the influence of International Organizations, have affected the inclusiveness and scope of services of the states' policies on education. The author argues that although the impact of the French colonization is extremely apparent, Senegal is slowly finding its way into building a Senegalese schooling system that reflects the realities of the different communities more than before, through inclusion of local languages in the curriculum, and modernizing Islamic schools to reach more students, thus increasing the inclusiveness and scope of services provided to cover a larger population.Deutsche Forschungsgemeinschaft (DFG)4
Physics-based data-driven simulation of debinding failure and sintering deformation in metal binder jetting
No full textDebinding failure, sintering distortions are two of the main challenges in manufacturing of intact and dimensionally precise components with metal binder jetting technology. In the current research, the challenges are addressed by developing physics-based data-driven numerical simulations.
Using thermos-optical observations it is demonstrated that debinding failure occurs when the binder is burnt-off from the green parts which lead to the strength reduction of the components. Through a design of experiment on self-stressing samples, it is resulted that stress on the specimens and the print direction are important factors which may affect debinding failure. A simulation-based Weibull model is developed to consider stress and print direction of the samples to predict he failure probability of green parts during debinding. The collected data from the design of experiment are used to fit the parameters of the simulation-based Weibull model. Validation evidence shows that the developed model is able to predict the failure probability of green parts. Furthermore, the model is detect the failure-prone zones with an acceptable accuracy.
The creep-like behavior of sintering deformations can be captured by a rate-dependent material model. Therefore, a phenomenological thermo-elasto-viscoplastic material model in the scheme of finite element method can simulate the thermal, elastic and viscoelastic deformations of sintering bodies in a component scale. The aforementioned material model is calibrated for metal binder jetting technology with dilatometry, Dynamic Differential Calorimetry, Laser Flash Analysis, metallographic analysis, and thermos-optical measurements. The validation studies reveals that without considering the characteristics of MBJ green parts such as density variations and anisotropy, the required industrial-acceptable tolerances cannot be achieved by simulations. Using a data-driven approach and with a wider range of experimental data, the material model is developed in a generic format with the ability to adopt for new manufacturing parameters. The experimental study enabled the estimation of porosity-dependent anisotropy, thermal expansion coefficient, and viscosity. Moreover, with the data-driven approach, the green part properties such as density variations and dimensions can be predicted and fed into the material model. The predicted deformations from the data-driven material model have a good agreement with the validation data.
Taking advantage of the data-driven numerical simulation and by introducing a compensation algorithm, sintering deformations of a given geometry are iteratively calculated and reversed to prepare a compensated configuration of the geometry. The presented approach results in manufacturing of MBJ parts with international tolerance grade of 14. Moreover, an experimental-based compensation technique is developed which takes use of previously calculated deformation vectors from numerical simulations and scan data of as-sinter configuration. Measuring the deviation between the as-sinter and the target geometry with the help of the normalized deformation vectors from simulations considers the physics of deformation and enables manufacturing of MBJ parts with a higher accuracy, achieving an international tolerance grade of 13
Comparing photorealism in game engines for synthetic maritime computer vision datasets
No full textComputer vision for real-world applications faces data acquisition challenges, including accessibil- ity, high costs, difficulty in obtaining diversity in scenarios or environmental conditions. Synthetic data usage has surged as a solution to these obstacles. Leveraging game engines for synthetic dataset creation effectively enriches training datasets with increased diversity and richness. The choice of game engine, pivotal for generating photorealistic simulations, significantly influences synthetic data quality.
This thesis aims to compare Unreal Engine’s and Unity Engine’s capabilities in generating synthetic maritime datasets to support ship recognition applications. To this end, the real-world maritime dataset ShipSG has been replicated in the corresponding game engines to recreate the same scenarios. To this end, a true-to-scale 3D model of the Doppelschleuse was crafted using Blender, aiming to reproduce the scenery of the ShipSG images. This model is further used in the corresponding game engines, along with 3D models of different vessels, to recreate these scenarios in rendered synthetic datasets.
The performance of the generated synthetic datasets is benchmarked against the real-world ShipSG dataset using the YOLOv8 model for ship segmentation. The comparison includes an assessment of performance differences between manually annotated synthetic datasets and those with auto-generated annotations by Unity Engine. Additionally, the comparison investigates ef- fects, such as sunlight presence and lens distortion, to find the configuration that most enhances performance when using YOLOv8. The dataset generated using Unity engine with manual annota- tions, both with and without lens distortion, provided the best accuracy in ship recognition (mAP of 72.3%). Both were used to augment the ShipSG dataset to train YOLOv8. The configuration with lens distortion provides the highest mAP increase, of 0.4% compared with YOLOv8 perfor- mance on ShipSG when no synthetic data is used (76.5% vs 76.9%). This evidence underscores that utilizing game engines can effectively support and enhance ship recognition tasks.
This thesis demonstrates the potential of synthetic datasets to augment real-world maritime data, highlights the importance of detailed and accurate 3D modelling, and systematically provides a methodology to select the most fitting game engine for the generation of photorealistic images to enhance maritime computer vision applications
Fish community dynamics in a cold temperate tidal lagoon in the Wadden Sea, in relation to changes in environmental conditions
No full textThe thesis investigated the effects of long-term and seasonal changes in environmental conditions on fish communities in the Wadden Sea. Using a monthly fish monitoring dataset from 2007 to 2019, a total of 55 fish species were recorded, including 8 new observations of Lusitanian, boreal, and Atlantic species, while four species from earlier surveys (1989-1995) were no longer present. The fish community was dominated by 22 species, which accounted for over 95% of the total abundance. These species exhibited three distinct trends: dome-shaped, increasing, or decreasing, influenced by winter temperatures which impacted recruitment. The analysis revealed seasonal groupings based on species’ temperature preferences, affecting their migration patterns. Warming autumn temperatures delayed cod (Gadus morhua) immigration and whiting (Merlangius merlangus) emigration into the Wadden Sea.
Environmental factors, primarily water temperature, salinity, and chlorophyll a, explained 18% of fish community variation on a seasonal basis and 10% on an inter-annual basis. Species richness was higher at 5°C and 15°C, reflecting seasonal immigration and emigration patterns. However, species diversity was negatively correlated with water temperature, as Atlantic herring (Clupea harengus) and small sand eel (Ammodytes tobianus) dominated the summer, and whiting dominated autumn.
Species richness declined with increasing water depth, as more species migrated to intertidal habitats during high tide. Evenness increased with water depth near seagrass meadows and bivalve beds, while pelagic species entered deep tidal channels during high tide.
Fifteen young-of-the-year YOY fish species were observed at various developmental stages, with most supplied from the North Sea. Environmental factors significantly explained 39% of YOY fish variations. Clupea harengus had two cohorts (autumn and spring hatched), while Nilsson’s pipefish (Syngnathus rostellatus) had one cohort spawned within the Wadden Sea
Drivers of Pleistocene to Holocene sea-level changes in the Southwestern Atlantic
No full textGlobal mean sea levels have been rising since the last century; this trend is expected to continue as the planet faces a warmer future. However, the rate and magnitude of this rise remain subject to debate, making decisions about land use and coastal management difficult. Sea level changes are not linear. In fact, they are driven by an intricate relationship between eustatic (i.e., global), isostatic, and local factors through time. Therefore, there is a clear need for precise and accurate data covering various spatiotemporal scales. Quaternary sea-level records offer valuable data to improve our understanding of these complex sea-level dynamics and enhance the predictions of future sea-level scenarios. In particular, interglacial records provide sea-level variability data under warm climate conditions. Marine Isotope Stage 5 (~125 to 80 ka) represents the most recent interglacial period when the Earth's climate was warmer than the pre-industrial, and the sea level was higher than today, leaving geological and biological traces of rising sea levels around the world. Especially, the southwestern Atlantic is considered a hot spot for past sea-level dynamics due to the abundance and preservation of sea-level indicators. This dissertation aims to provide an overview of the state-of-the-art of sea-level research in this broad region, provide context on the accuracy of published data from the Pleistocene to the Holocene interglacials, discuss the uncertainties surrounding them, and propose new methodological approaches to improve the interpretations
The effect of acute warming on protein turnover and oxygen demand in stenothermal and eurythermal eelpouts
No full textThe increase in CO2 in the atmosphere due to the burning of fossil fuels is the main cause of climate change and thus global warming. Climate change has fundamental consequences for all organisms, including marine life. Ectothermal organisms, such as fish, are particularly affected, since their body temperature is equal to their environment. Fish have adapted to diverse temperature conditions depending in different climatic regions and thus exhibit a range of temperature adaptations. Fish in polar regions, such as Antarctic fish species, are adapted to constantly cold temperatures, while fish in temperate regions are adapted to seasonal temperature fluctuations and can survive in wide temperature windows.
Thermal adaptation can be investigated by acclimating fish to certain temperatures over a long period (long-term acclimation) or during acute temperature changes (acute warming). This study investigates the differences and similarities in thermal adaptions of stenothermal and eurythermal fish during acute warming events. For this comparison, the closely related eelpout species Pachycara brachycephalum from the Southern Ocean and Zoarces viviparus from the North Sea were selected as experimental animals. During these experiments, water temperature was increased from 0°C to 10°C at a rate of 2°C day-1 for P. brachycephalum. For Z. viviparus, the temperature was increased from 4°C to 22°C at a rate of 3°C day-1. Isotopically labelled phenylalanine was injected intraperitonially at several temperature levels (P. brachycephalum: 0, 2, 4, 6, 8 and 10°C; Z. viviparus: 4, 10, 13, 16, 22°C) and after 1.5- and 3-hours gill and white muscle tissues were sampled. Protein synthesis rate was determined in both tissue types and protein degradation analyzed in the muscle by measuring cathepsin D activity and via untargeted metabolic profiling using NMR (nuclear magnetic resonance). Furthermore, oxygen consumption was measured during acute warming to draw conclusions about energy requirements.
In P. brachycephalum, the rate of protein synthesis in white muscle did not change with increasing temperature. In contrast, the protein synthesis rate in Z. viviparus increased up to 16°C and then decreased slightly at 22°C. Comparing the two species at a common temperature (4 and 10°C), the protein synthesis rate in P. brachycephalum was 2-3-times higher, while the activity of cathepsin D was 10 times higher in white muscle. Both the rate of protein synthesis in the gills and whole animal oxygen demand increased exponentially in both species and no differences were found between the species when compared at a common temperature.
In conclusion, these data suggest that protein synthesis in P. brachycephalum is cold-compensated and is maintained at a high rate at low temperatures. The protein synthesis rate in the white muscle of Z. viviparus only reached that of P. brachycephalum near its thermal optimum. This cold adaptation may enable P. brachycephalum to survive in the world's coldest ocean. In contrast, Z. viviparus responds very quickly to temperature differences, which occur regularly in the North Sea
Unexpected Gender Stereotypes in AI-generated Stories: Hairdressers Are Female, but so Are Doctors
No full textWe investigated gender bias in short stories generated by ChatGPT by generating stories about characters with specifed occupations and analyzing the gender assigned to these characters. On the one hand, stereotypes about professions typically associated with women are strongly reinforced, with almost all of the characters in these stories being female, well beyond what would be expected based on human biases. On the other hand, among occupations that humans typically associate with men, the generated stories reinforce these stereotypes in some cases (particularly blue-collar occupations), while reversing them to be strongly stereotypically female in other cases (notably highly regarded professions such as doctors, scientists, attorneys, or astronauts).11512
Green transition and the role of smart specialisation in Europe - an empirical examination
No full textThe thesis is rooted in the spheres of regional innovation, and green transition, using the European instrument of smart specialisation as a practical example for quantititive analysis. The individual chapters strive to address the topic of regional innovation and sustainability from different angles by exploiting new data sources and applying new analytical methods. One chapter focuses on an analysis of the role of environmental sustainability in both regional innovation and smart specialisation research by applying a bibliometric approach. The second article focuses on interregional cooperation in environmental innovation in Europe by constructing cooperation networks based on data on Horizon 2020 research projects. The third article takes the circular economy as an example of a regional policy for environmental sustainability and develops a novel index to quantify regional performance in this regard. The fourth article constructs an econometric model on basis of patent data to demonstrate that this regularly used data can still reveal new information on the factors that determine regional green specialisations. The chapters recognise the call for novel metrics for inform policies and strategies and in each case discuss the policy implications of the respective findings. Among the central findings are a crucial role of innovation for a successful transition, the differentiated picture painted by analysing the regional rather than national or supra-national levels, and a need for adaptation of existing policy instruments