Recent Submissions
Longitudinal and transverse muscle stiffness change differently with knee osteoarthritis and do not align with stiffness sensation
(2025) Dieterich, Angela V.; Skerl, Katrin; Paskali, Filip; Gizzi, Leonardo; Azan, Mehrin; Carvalho, Gabriela F.; Kohl, Matthias; Haueise, Andreas
Knee osteoarthritis (OA) is a prevalent joint condition associated with disability, pain, and stiffness in the muscles surrounding the knee. Myofascial and massage techniques are employed to alleviate these symptoms. Unclear is whether muscle stiffness is measurably increased in the painful muscles, and how measured muscle stiffness relates to perceived stiffness, pain, and functional impairment. Given muscle anisotropy, stiffness changes may occur in the longitudinal plane parallel to muscle fibers or perpendicularly in the transverse plane. Shear wave velocity (SWV) was measured in both scanning planes in 21 individuals with diagnosed knee OA, 21 sex- and age-matched controls, and 20 young controls , focusing on the gastrocnemius medialis and vastus lateralis muscles under four conditions: (a) resting state, (b) holding the shank against gravity, (c) double-leg stance, and (d) single-leg stance. Median stiffness measures, the ratio of longitudinal-to-transverse stiffness, and the ratio of single-leg stance-to-baseline stiffness were compared between groups using the Kruskal- Wallis and Pairwise Asymptotic Wilcoxon rank sum tests. Correlations with the Knee Injury and Osteoarthritis Outcome Score and the Tampa Scale of Kinesiophobia were examined. Longitudinal stiffness of the gastrocnemius medialis muscle was significantly lower in the OA group at double-leg (P = 0.033) and single-leg stance (P = 0.019), with tendencies toward lower median stiffness in both muscles across most tasks. Transverse stiffness of the vastus lateralis muscle was significantly higher in the OA group at baseline (P = 0.027), with tendencies toward higher median stiffness in both muscles across most tasks. Significant moderate to excellent correlations support the clinical relevance of both longitudinal and transverse stiffness measurements. Measured and perceived stiffness were not correlated. Study results suggest that knee OA may differentially affect muscle stiffness in the longitudinal and transverse planes and that transverse stiffness measures may have clinical relevance.
Benchmarking pre-trained language models for schema-agnostic entity resolution
(2024) Bothmann, Jan
Data integration is a process in which data from different sources are brought together to create a unified picture of the data. A vital aspect of this integration is Entity Resolution, which tries to identify elements that correspond to the same entity across multiple datasets. The complexity of ER tasks can vary significantly, as data exhibits different characteristics and levels of structuredness, which can influence the difficulty of the task.
In this thesis, we evaluate how current state-of-the-art Entity Resolution systems perform when dealing with semi-structured data. To do this, several semi-structured ER benchmarks covering data from various domains were created for evaluation. Additionally, to explore how different data characteristics or other influencing factors impact the performance of matching systems, we developed the Benchmark Creator. This tool allows us and other users to generate benchmarks where data exhibits specific characteristics that may influence the complexity of the ER task.
We used Ditto, Sudowoodo and the GPT4o-mini model to evaluate performance on the newly created benchmarks. Our evaluation reveals that Ditto and the GPT4o-mini model can effectively perform schema-agnostic ER on semi-structured data.
Camera-based mobile applications for movement screening in healthy adults : a systematic review
(2025) El-Rajab, Inaam; Klotzbier, Thomas J.; Korbus, Heide; Schott, Nadja
Background: In recent years, the proliferation of mobile applications in the health and fitness sector has been rapid. Despite the enhanced accessibility of these systems, concerns regarding their validation persist, and their accuracy remains to be thoroughly evaluated compared to conventional motion analysis methodologies. Furthermore, there is a paucity of evidence regarding real-time feedback and movement quality assessment. Consequently, this systematic review aims to evaluate the current state of camera-based mobile applications for movement screening in healthy adults, focusing on specific types of movement.
Methods: A systematic literature search was conducted in four databases - PubMed, ScienceDirect, Web of Science, and IEEE Xplore - covering the period from 2000 to 2024. The search strategy was based on key terms related to four main concepts: screening, mobile applications, cameras, and physical activity. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines were followed. The study was registered a priori on PROSPERO (Registration ID: CRD42023444355) to ensure transparency and prevent selective reporting of outcomes.
Results: Of the 2,716 records initially identified, eight studies met the specified inclusion criteria. The studies were primarily concerned with fitness exercises, gait analysis, and sport-specific movements. Some studies demonstrated high reliability compared to gold standard systems, while others reported technical limitations such as camera positioning and data interpretation issues. Feedback mechanisms varied, with many applications lacking personalized real-time correction.
Conclusion: Despite the potential of smartphone-based movement screening applications, particularly their accessibility and affordability, challenges remain regarding accuracy and user feedback. Precise measurements comparable to established methods are crucial for application-oriented camera-based movement screening. Equally important are improving real-time feedback, expanding the types of movement that can be assessed, and ensuring broad applicability across different populations and environments to ensure sustainable use of application-based movement screening.
Methods: A systematic literature search was conducted in four databases - PubMed, ScienceDirect, Web of Science, and IEEE Xplore - covering the period from 2000 to 2024. The search strategy was based on key terms related to four main concepts: screening, mobile applications, cameras, and physical activity. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines were followed. The study was registered a priori on PROSPERO (Registration ID: CRD42023444355) to ensure transparency and prevent selective reporting of outcomes.
Results: Of the 2,716 records initially identified, eight studies met the specified inclusion criteria. The studies were primarily concerned with fitness exercises, gait analysis, and sport-specific movements. Some studies demonstrated high reliability compared to gold standard systems, while others reported technical limitations such as camera positioning and data interpretation issues. Feedback mechanisms varied, with many applications lacking personalized real-time correction.
Conclusion: Despite the potential of smartphone-based movement screening applications, particularly their accessibility and affordability, challenges remain regarding accuracy and user feedback. Precise measurements comparable to established methods are crucial for application-oriented camera-based movement screening. Equally important are improving real-time feedback, expanding the types of movement that can be assessed, and ensuring broad applicability across different populations and environments to ensure sustainable use of application-based movement screening.
Salivary cortisol and alpha-amylase as stress markers to evaluate an individualized music intervention for people with dementia : feasibility and pilot analyses
(2024) Hillebrand, Mareike Christina; Sindermann, Cornelia; Montag, Christian; Wuttke, Alexandra; Heinzelmann, Rebecca; Haas, Heidrun; Wilz, Gabriele
Objectives: We investigated salivary biomarkers of stress, more specifically, cortisol and alpha-amylase, to evaluate effects of individualized music listening (IML) in people with dementia.MethodParticipants were N = 64 nursing home residents with dementia (meanage = 83.53 ± 7.71 years, 68.8% female). Participants were randomly assigned to either listening to their favorite music every other day for a period of six weeks (intervention), or standard care (control). Using the Saliva Children`s Swab (SCS), saliva was collected before, after, and 20 min after IML sessions at the beginning and end of the intervention period for the analysis of salivary alpha-amylase and cortisol.
Results: Using the SCS was feasible in people with dementia. Nevertheless, there was no effect of IML on salivary stress markers.
Discussion: Although using SCS was feasible, active patient engagement is required. Future studies need to corroborate findings in larger samples.
Trial registration: German Clinical Trials Register: DRKS00015641, ISRCTN registry: ISRCTN59052178.
Results: Using the SCS was feasible in people with dementia. Nevertheless, there was no effect of IML on salivary stress markers.
Discussion: Although using SCS was feasible, active patient engagement is required. Future studies need to corroborate findings in larger samples.
Trial registration: German Clinical Trials Register: DRKS00015641, ISRCTN registry: ISRCTN59052178.
Totally geodesic submanifolds and polar actions on Stiefel manifolds
(2024) Gorodski, Claudio; Kollross, Andreas; Rodríguez-Vázquez, Alberto
We classify totally geodesic submanifolds of the real Stiefel manifolds of orthogonal two-frames. We also classify polar actions on these Stiefel manifolds, specifically, we prove that the orbits of polar actions are lifts of polar actions on the corresponding Grassmannian. In the case of cohomogeneity one actions we are able to obtain a classification for all real, complex and quaternionic Stiefel manifolds of k-frames.
Realization of alkaline-earth circular Rydberg qubits in optical tweezer arrays
(2024) Hölzl, Christian; Pfau, Tilman (Prof. Dr.)
Individually controlled neutral atoms in arrays of optical tweezers have enabled rapid advances in the development of quantum computers and simulators over the last years. The finite lifetime of highly excited Rydberg atoms, which provide the interactions between the individual atoms, fundamentally limits the coherence times and gate fidelities of these machines. Circular Rydberg states are a promising candidate to overcome those limitations since their maximum angular momentum allows them to be protected from decay.
In this work, I will report on the design and setup of a room-temperature quantum simulator based on circular Rydberg states of strontium atoms trapped in an optical tweezer array. With this setup, the tweezer-trapped circular Rydberg state qubits are realized in an alkaline-earth atom for the first time.
A sophisticated electrode structure stabilizes the qubit states against black-body-radiation and enables the creation of the longest lived Rydberg states ever observed in a room-temperature setup.
How do ML practitioners perceive explainability? : an interview study of practices and challenges
(2024) Habiba, Umm-e-; Habib, Mohammad Kasra; Bogner, Justus; Fritzsch, Jonas; Wagner, Stefan
Explainable artificial intelligence (XAI) is a field of study that focuses on the development process of AI-based systems while making their decision-making processes understandable and transparent for users. Research already identified explainability as an emerging requirement for AI-based systems that use machine learning (ML) techniques. However, there is a notable absence of studies investigating how ML practitioners perceive the concept of explainability, the challenges they encounter, and the potential trade-offs with other quality attributes. In this study, we want to discover how practitioners define explainability for AI-based systems and what challenges they encounter in making them explainable. Furthermore, we explore how explainability interacts with other quality attributes. To this end, we conducted semi-structured interviews with 14 ML practitioners from 11 companies. Our study reveals diverse viewpoints on explainability and applied practices. Results suggest that the importance of explainability lies in enhancing transparency, refining models, and mitigating bias. Methods like SHapley Additive exPlanations (SHAP) and Local Interpretable Model-Agnostic Explanation (LIME) are frequently used by ML practitioners to understand how models work, while tailored approaches are typically adopted to meet the specific requirements of stakeholders. Moreover, we have discerned emerging challenges in eight categories. Issues such as effective communication with non-technical stakeholders and the absence of standardized approaches are frequently stated as recurring hurdles. We contextualize these findings in terms of requirements engineering and conclude that industry currently lacks a standardized framework to address arising explainability needs.
Namibia and Germany: Two perspectives on strengths and struggles for a sustainable development
(Stuttgart : University of Stuttgart, Centre for Higher Education and Lifelong Learning, 2025) Braun, Thorsten; Gashi, Anita
A collection of essays written by students and researches during the 2024 seminar "Namibia and Germany: Two Perspectives on Strengths and Struggles for Sustainable Development", organized by the Center for Higher Education and Lifelong Learning at the University of Stuttgart and the SDG-Campus (www.sdg-campus.de). The essays reflect on sustainability challenges with focus on Namibian-German relations.
Zero-waste sand formworks for lightweight concrete structures
(2025) Kovaleva, Daria; Sobek, Werner (Prof. Dr. Dr. E.h. Dr. h.c.)
To address the growing urgent need to reduce resource consumption, embodied energy, and waste in construction, this thesis presents a new method for the zero-waste production of lightweight concrete structures using water-soluble sand formwork. The application of lightweight construction principles allows the creation of efficient and expressive structures with minimal material consumption and, consequently, an ecological footprint. Due to its ability to take any conceivable shape, concrete provides architects and engineers with virtually unlimited design freedom and is ideal for putting these principles into practice. However, despite the wide availability of design solutions known since the middle of the 20th century, lightweight concrete structures are still not widely used due to the lack of adequate sustainable production methods. This often involves formwork manufacturing, which is still labor-intensive and wasteful and accounts for over two-thirds of the production budget. Digital production methods, such as additive and subtractive manufacturing, enable highly precise creation of geometrically complex objects. However, their broader application in formwork production is limited by their narrow specialization in the types of geometry produced, the generation of waste during processing, and the use of toxic and non-recyclable formwork materials. Therefore, the emergence of a flexible and environmentally friendly formwork method suitable for producing geometrically complex structures is necessary for the broader application of lightweight construction with concrete.
Offering a comprehensive approach to the above-described problem, this thesis proposes a novel zero-waste technology to produce lightweight concrete structures using additive manufacturing of a specially developed water-soluble sand and binder mixture. The powder-bed-based 3D printing of granular materials gives the greatest freedom in terms of geometric complexity, while the water-soluble nature of the formwork material mix allows it to be fully recycled after casting and reused in further production cycles. Following the overall goal of promoting lightweight concrete construction, this technology also has an inverse effect on designing lightweight structures. It makes it possible to realize structural morphologies that would be inefficient or even impossible to produce with conventional formwork methods. The water solubility of the formwork material allows the creation of structures with geometrically complex external shapes and internal configurations. This enables not only improved structural performance but also the integration of other functional elements, such as MEP systems, acoustic and thermal insulation.
The work on the thesis includes the conceptualization of a closed-loop production cycle, the creation of an automated manufacturing process based on 3D printing of sand molds with a specially developed material mix, and the development of necessary accompanying CAD-CAM tools. The proposed technology is validated in the production of formworks for lightweight concrete structures of various scales, from small-scale prototypes to architectural demonstrator.
RepEnTools : an automated repeat enrichment analysis package for ChIP-seq data reveals hUHRF1 Tandem-Tudor domain enrichment in young repeats
(2024) Choudalakis, Michel; Bashtrykov, Pavel; Jeltsch, Albert
Background. Repeat elements (REs) play important roles for cell function in health and disease. However, RE enrichment analysis in short-read high-throughput sequencing (HTS) data, such as ChIP-seq, is a challenging task.
Results. Here, we present RepEnTools , a software package for genome-wide RE enrichment analysis of ChIP-seq and similar chromatin pulldown experiments. Our analysis package bundles together various software with carefully chosen and validated settings to provide a complete solution for RE analysis, starting from raw input files to tabular and graphical outputs. RepEnTools implementations are easily accessible even with minimal IT skills (Galaxy/UNIX). To demonstrate the performance of RepEnTools , we analysed chromatin pulldown data by the human UHRF1 TTD protein domain and discovered enrichment of TTD binding on young primate and hominid specific polymorphic repeats (SVA, L1PA1/L1HS) overlapping known enhancers and decorated with H3K4me1-K9me2/3 modifications. We corroborated these new bioinformatic findings with experimental data by qPCR assays using newly developed primate and hominid specific qPCR assays which complement similar research tools. Finally, we analysed mouse UHRF1 ChIP-seq data with RepEnTools and showed that the endogenous mUHRF1 protein colocalizes with H3K4me1-H3K9me3 on promoters of REs which were silenced by UHRF1. These new data suggest a functional role for UHRF1 in silencing of REs that is mediated by TTD binding to the H3K4me1-K9me3 double mark and conserved in two mammalian species.
Conclusions. RepEnTools improves the previously available programmes for RE enrichment analysis in chromatin pulldown studies by leveraging new tools, enhancing accessibility and adding some key functions. RepEnTools can analyse RE enrichment rapidly, efficiently, and accurately, providing the community with an up-to-date, reliable and accessible tool for this important type of analysis.