University of Konstanz
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Computer vision in animal behaviour : Markerless approaches for fine-scaled behaviour quantification in birds
No full textAnimals interact with the world through their behaviour. Over the last few decades, technological advancements have provided new ways for animals to be monitored and measured, offering novel insights into the study of animal behaviour. One such advance is the popularization of computer vision methods to measure the position, outline, posture, and behaviour of animals. While these methods have developed at an exponential rate over the last decade, uptake of methods for applications in animal behaviour is still limited, due to various challenges and obstacles that might have prevented computer vision innovations to be directly applied to biological studies. To overcome these challenges and better bridge the two fields, this thesis proposed a generalized framework for computer vision projects in animal behaviour applications, and demonstrated the key opportunities that can facilitate collaboration. Within this framework, the role of the "computer vision practitioner" was emphasized, whose main goal is to implement computer vision pipelines, but also oversees the whole research process.
As a demonstration of how this framework can be implemented, this thesis presented two main lines of research. The first is the development of multi-animal, markerless 3D posture estimation methods for fine-scaled behavioural quantification in birds, with the primary aim of measuring head rotation to estimate gaze and attention. To achieve this goal, Chapter 1 presented 3D-POP, a large scale 2D-3D posture dataset in pigeons, and Chapter 2 presented 3D-MuPPET, a framework for multi-animal 3D posture estimation in captivity and the wild. This was the first demonstration of 3D posture estimation for more than 4 individual animals simultaneously, providing a novel framework for fine-scaled, markerless tracking of animal movement and behaviour. The system was extended in Chapter 3, 3D-SOCS, which proposed a synchronized camera system deployed in the wild for 3D posture estimation of great tits. Finally, Chapter 4 proposed a way of evaluating computer vision models based on its performance for the final application using application-specific metrics, through case studies in gaze estimation of pigeons and abundance estimation of chimpanzees. Taken together, the first part of this thesis presented a series of pioneering methods for markerless 3D posture estimation of animals, opening the doors for fine-scaled behavioural tracking across study systems and species.
The second part of the thesis aimed to solve the problem of automating behavioural coding in long-term study systems. Chapter 5 presented CHIRP, a task-diverse dataset of Siberian Jays in the wild, supporting action recognition, re-identification, posture estimation, segmentation, object detection, and trajectory tracking. By introducing a novel application-specific benchmark for extracting biologically meaningful measures, the dataset provided a way for computer vision innovations to be directly tested in the context of the final application. Finally, Chapter 6 proposed YOLO-Behaviour, a robust framework for behavioural quantification from videos, demonstrated over 5 different case studies. Collectively, the second part of the thesis laid a foundation for both individual recognition and behavioural annotation from videos, highlighting the value of automating manual annotation, especially in long-term study systems, creating increased sample size for hypothesis testing.
Through two lines of research, this thesis proposes that by identifying key synergies and opportunities between the two fields, collaboration between computer vision and biology can be substantially accelerated and improved, with emphasis on the important role of "computer vision practioners". The thesis concluded by formulating these interdisciplinary challenges and opportunities, towards a future where computer vision innovation can contribute to novel data collection procedures across animal systems. With careful collaboration and development, computer vision has the potential to revolutionize the study of animal behaviour, while also transforming fields such as conservation, animal welfare, and beyond.publishe
Interfacial and Crystalline Gauche OCH<sub>2</sub>–CH<sub>2</sub>O Layers in Biodegradable and Recyclable Polyethylene-like Polyesters Detected by Nuclear Magnetic Resonance
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Singlet-Triplet and Exchange-Only Flopping-Mode Spin Qubits
No full textSemiconductor-based spin qubits embedded into a superconducting microwave cavity constitute a fast-progressing and promising platform for realizing fast and fault-tolerant qubit control with long-range two-qubit coupling. The flopping-mode spin qubit consists of a single electron in a double quantum dot; it combines a charge qubit with a spin qubit. With its strong and tunable cavity coupling, the flopping-mode qubit is proven to be well suited for low-power qubit control and cavity-mediated long-range quantum gates. The singlet-triplet (ST) and exchange-only (EO) qubits are multielectron realizations that go without broadband control and are protected from some types of noise, but are challenging to couple to each other and to microwave cavities. We combine the flopping-mode concept with the ST and EO qubits and propose two new flopping-mode qubits that consist of three (four) quantum dots, occupied by two (three) electrons near the (1,0,1) ↔(0,1,1) [(1,0,1,1) ↔(0,1,1,1)] charge transition. The two-electron system augments the ST0 spin qubit with a charge qubit that interacts transversally and longitudinally with a cavity. Both couplings are highly tunable, and the longitudinal coupling distinguishes the flopping-mode ST qubit from the regular flopping-mode qubit. The longitudinal coupling allows for nondissipative universal control similar to superconducting transmon qubits. The EO flopping-mode qubit comprises four dots occupied by three electrons and opens a new possibility to perform two-qubit gates for EO qubits that are challenging to perform directly with the exchange coupling. We use input-output theory to provide means of extracting the coupling strengths from cavity transmission data.publishe
Effort and boredom shape our experience of time
No full textSituations change over time, and so does our experience of them. For example, a task may initially feel engaging but can, over time, become monotonous and boring. Similarly, as processing demands increase or one’s momentary capabilities decline, the same task can feel more or less effortful. The dynamics of these task-induced sensations matter because boredom and perceived effort shape behavior by driving optimization of resource utilization. Time is among the most fundamental resources to which people tend to be acutely sensitive across contexts. Here, we propose that the sensations of boredom and effort influence how the passing of time is experienced. Specifically, both states are linked to changes in interoception—the perception of internal bodily signals—which is known to play a key role in time perception. This proposal offers a framework for understanding how fundamental regulatory sensations, such as boredom and effort, shape temporal experience through interoceptive mechanisms. We highlight the insular cortex as a potential hub mediating the effects of interoceptive signals on time perception, integrating feelings of boredom and effort, and their influence on the experience of time.publishe
Investigating the functional aspects of the AZUL domain of the ubiquitin ligase E6AP
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Public Health Spending in Africa : Cyclicality, Asymmetries, and COVID-19
No full textThe COVID-19 pandemic has renewed the global focus on the role of public health spending, particularly in developing regions where fiscal space is mostly limited. Many African countries have started reassessing the health sector as a core economic resilience component. This study examines how government health expenditure responds to macroeconomic fluctuations in African countries. Attention was given to asymmetries between positive and negative periods of GDP growth and the impact of COVID-19 on these dynamics. The analysis uses annual data from 45 African economies from 2000 to 2022 and applies a panel NARDL framework to capture nonlinear and dynamic relationships. The sample is further disaggregated into low-income and middle-income groups. The results from the full sample indicate a procyclical pattern of health spending, where expenditure rises during economic expansions, but it discloses an acyclical relationship during recessions. Further analysis reveals that health spending in low-income countries follows a similar procyclical trend, while middle-income countries exhibit a countercyclical response to positive and negative growth shocks. Inflation consistently reduces health spending across the sample. The COVID-19 period has altered the cyclical pattern of health expenditure, at least in the short-run, especially for low-income countries. These findings highlight the need for more resilient and countercyclical fiscal strategies in the health sector, specifically during economic downturns, to ensure sustained investment.publishe
Zinc and Cobalt Coordination Polymers Based on the Redox-Active Linker 4,4′-(Phenazine-5,10-diyl)dibenzoate : Structures and Electrochemical Properties
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Topological Harmonic Generation of Nonlinear Optical Skyrmions
No full textSkyrmions are quasi-particles with a topologically stable structure, having widespread relevance in fields like condensed matter physics, plasmonics, and photonics. Initially proposed to describe baryons and atomic nuclei, they have since been extensively studied in spintronic devices for their unique magnetic properties. Recently, the exploration of optical skyrmions generation and their interaction of matters has attracted wide interest in optics and photonics. Previous studies have been mostly limited in the linear optical regime. The nonlinear interaction and topological transformation of optical skyrmions with matters has not been well explored. In this work, we report the second and third nonlinear harmonic generation driven by optical skyrmions by interacting with crystals possessing different rotational symmetries. We demonstrate the nonlinear transformation of optical skyrmions with different topological charges in solids. The nonlinear optical harmonic skyrmions are formed with coherent superpositions of higher-order skyrmions, allowing conversions between skyrmions and anti-skyrmions. A quantum urn model is introduced to explain the generation of low-order and high-order harmonic skyrmions. This work presents the nonlinear interaction of the topological light fields with crystalline symmetry and provides novel insights into the efficient generation and robust control of the harmonics of skyrmions. It has implications on the application of secure communication, precise metrology, and quantum information.publishe
Modeling and Mechanistic Study of Polyethylene Chain Cleavage during Ball Milling
No full textMechanochemical conversion of polyethylene (PE) and polypropylene was shown to produce monomers and is thus interesting for chemical polymer recycling. As these polymers make up more than 50% of the worldwide polymer production, studying their conversion during ball milling is especially relevant. However, fundamental knowledge on the effect of crystallinity, degree of polymerization, entanglement and temperature on the conversion is lacking due to the difficulty in producing polyolefins with controlled chain length and dispersity. Here we synthesize PE by a controlled chain growth polymerization and study its degradation during ball milling at cryogenic conditions, at room temperature (RT), with and without air, and using either steel or zirconia grinding spheres. Resulting molecular weight distributions are fitted using a statistical chain cleavage model suggesting a statistical Gaussian distribution of chain cleavage probability around the middle of the chain. This is likely because if the chains are fixed in an entanglement or crystal at two points, they cannot slip out and force can act on them leading to cleavage. That the chain is fixed at both sides of a possible cleavage location is most likely if the cleavage location is in the center of the chain. Chain cleavage is also promoted when entangled domains exist that link crystalline regions. A micelle grown single crystal ultrahigh molecular weight PE without entanglements was milled and its molar mass decreased much less compared to the same sample that was annealed to create entanglements. However, in contrast to previous studies and common expectations, the initial molar mass of the polymer, the degree of crystallinity and the brittleness of the sample did not have a measurable influence on chain cleavage. While the decrease in molar mass was faster at cryogenic conditions compared to RT, nuclear magnetic resonance (NMR) results suggest that this is due to a suppression of radical recombination rather than the higher brittleness of the material below its glass transition temperature (∼−120 °C). Similarly, the number of permanent scissions increased by up to 2.6 times under air compared to nitrogen atmosphere, especially in combination with steel milling spheres. NMR spectra of the milled samples suggest that the reaction of mechanochemically formed chains with air suppresses recombination.publishe
Existential boundaries : Jaspers on the interminable struggle with our finitude
No full textIn his later work on philosophical faith, Jaspers argues that acknowledging the limits of knowledge can be releasing. However, in his works on boundary situations, when he discusses the boundaries of life and action, he claims that acknowledging these boundaries can provide existential elucidation, but not peace of mind. In this essay, I explore the concept of epistemic and practical boundaries,
demonstrating that these notions are absolute metaphors whose meaning is revealed only through a practical-existential understanding. I interpret Jaspers’ concept of existential elucidation as such an understanding and argue that acknowledging epistemic and practical boundaries can be releasing, but is an everlasting process.publishe