Eldorado - Repositorium der TU Dortmund

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Aktuellste Veröffentlichungen

Design of optimal concentrations for in vitro cytotoxicity experiments
(2024-11-16) Schürmeyer, Leonie; Peng, Chen; Albrecht, Wiebke; Brecklinghaus, Tim; Baur, Pauline; Hengstler, Jan G.; Schorning, Kirsten
Concentration-dependent cytotoxicity experiments are frequently used in toxicology. Although it has been reported that an adequate choice of concentrations improves the quality of the statistical inference substantially, a recent literature review of three major toxicological journals has shown that the corresponding methods are rarely used in toxicological practice. In this study the performance of different sets of concentrations, also called designs, are analyzed, while the overall goal is to promote the advantages of optimal design procedures and to present a user-friendly guideline for planning new cytotoxicity concentration-response experiments. We compare the frequently used log-equidistant design to a Bayesian design, which is constructed by methods of optimum design theory. Using both a dense data set of concentration-cytotoxicity data of valproic acid (VPA) and regular assay data of 104 substances, the performance of the different designs is analyzed in two scenarios, where detailed previous knowledge on VPA is available or not. The results show that it is critical to apply a specific design strategy to determine optimal concentrations for cytotoxicity testing. In particular, the Bayesian design technique with and without incorporating pre-existing knowledge of a specific test substance resulted in a more precise statistical inference than the other used designs. Finally, we present a guideline for upcoming experiments and an accessible user-friendly Shiny app (see http://shiny.statistik.tu-dortmund.de:8080/app/occe).
Light-driven modulation of proximity-enhanced functionalities in hybrid nano-scale systems
(2025-08-07) Benini, Mattia; Parlak, Umut; Bork, Sophie; Strohsack, Jaka; Leven, Richard; Gutnikov, David; Mertens, Fabian; Zhukov, Evgeny; Rakshit, Rajib Kumar; Bergenti, Ilaria; Droghetti, Andrea; Shumilin, Andrei; Mertelj, Tomaz; Dediu, Valentin Alek; Cinchetti, Mirko
Advancing quantum information and communication technology requires smaller and faster components with actively controllable functionalities. This work presents an all-optical strategy for dynamically modulating magnetic properties via proximity effects controlled by light. We demonstrate this concept using hybrid nanoscale systems composed of C₆₀ molecules proximitized to a cobalt metallic ferromagnetic surface, where proximity interactions are particularly strong. Our findings show that by inducing excitons in the C60 molecules with resonant ultrashort light pulses, we can significantly modify the interaction at the Cobalt/C60 interface, leading to a remarkable 60% transient shift in the frequency of the Co dipolar ferromagnetic resonance mode. This effect, detected via a specifically designed time-resolved Magneto-Optical Kerr Effect (tr-MOKE) experiment, persists on a timescale of hundreds of picoseconds. Since this frequency shift directly correlates with a transient change in the anisotropy field—an essential parameter for technological applications—our findings establish a new material platform for ultrafast optical control of magnetism at the nanoscale.
On the representation of piecewise quadratic functions by neural networks
(2025-09-09) Teichrib, Dieter; Schulze Darup, Moritz
Neural networks (NNs) are commonly used to approximate functions based on data samples, as they are a universal function approximator for a large class of functions. However, choosing a suitable topology in terms of depth, width and activation function for NNs that allow for low error approximations is a non-trivial task. For the approximation of continuous piecewise affine (PWA) functions, this task has been solved by showing that for every PWA function, there exist NNs with rectified linear unit (relu) and maxout activation that allow an exact representation of the PWA function. This connection between PWA functions and NNs has led to some valuable insights into the representation capabilities of NNs. Moreover, the connection was used in control for approximating the PWA optimal control law of model predictive control (MPC) for linear systems. We show that a similar connection exists between NNs and continuous piecewise quadratic (PWQ) functions by deriving topologies for NNs that allow an exact representation of arbitrary PWQ functions with a polyhedral domain partition. Furthermore, we demonstrate that the proposed NNs can efficiently approximate the PWQ optimal value function for linear MPC.
The FIFA 11 + Referees program improves knee proprioception in female futsal referees
(2025-09-17) Khosravi rad, Fatemeh; Zarei, Mostafa; Hosseini, Seyed Mohammad; Asgari, Mojtaba
While the FIFA 11 + Referees program (the 11 + Referees) is the only structured injury prevention program for referees, its effects on injury-related risk factors among referees remain underexplored. This study investigated the effects of the 11 + Referees on knee joint proprioception and dynamic balance. Thirty four female referees from the Tehran Premier Futsal League voluntarily participated and were randomly assigned to either a control group (n = 17) or the 11 + Referees group (n = 17). All participants underwent a baseline assessment including knee joint proprioception at angular velocities of 15°/s, 45°/s, and 60°/s, and position sense, as well as dynamic balance. Subsequently, the intervention group performed the 11 + Referees program three times weekly for 8 weeks, while the control group performed general warm-ups. Post-intervention, the same test battery was administered, and changes were analyzed to identify the program’s effects on the measures understudied. Significant improvements were observed in knee joint proprioception at 15°/s (F = 18.19, p < 0.001, η²=0.44), 45°/s (F = 4.07, p = 0.056, ηp²=0.15), and 60°/s (F = 6.63, p = 0.017, η²=0.22) in the intervention group. However, dynamic balance did not show significant improvement (F = 0.79, p = 0.38, η²=0.033). In conclusion, an eight-week application of the 11 + Referees enhanced knee joint proprioception in female referees with large effect sizes, but had no significant effect on dynamic balance. Improvements in proprioception may be attributed to neuromuscular adaptations resulting from regular program use. The absence of balance improvement could be due to the short intervention period and the hard futsal court surface, which may limit the effectiveness of certain balance exercises. Future studies should explore the program's effects on other injury risk factors and injury rates.
A reliable in vitro rumen culture system and workflow for screening anti-methanogenic compounds
(2025-12-01) Laric, Philip P.; Mortazavi, Armina; Wegrzyn, Ewa; Simon, Kathrin; Rittel, Pauline S.; Trefz, Florian M.; Sabass, Benedikt
Arguably the biggest man-made challenge of the century is halting climate change. Livestock’s methane (CH4) emissions, a greenhouse gas with a higher global warming potential than carbon dioxide (CO2), represent a prime target for reducing anthropogenic impact. While the reduction of enteric methane emissions through feed additives has been demonstrated, potent and affordable compounds inhibiting methanogenesis in ruminants are not yet well established. Reliable methods for reproducible cultivation of the rumen microbiome in the laboratory are an essential tool for the study of methanogenesis. We have developed a versatile setup that allows for the cultivation of the ruminal microbiome in a benchtop configuration and combines, miniaturizes, and improves existing systems. The design is based on standard laboratory equipment, including bottles, serological pipettes, tubing, and Luer-Lock valves. The apparatus enables long-term cultivation of primary cultures extracted from the rumen of slaughtered cattle. We describe rumen content acquisition, preparation, the cultivation procedure, and demonstrate the system’s performance. The efficacy of the system is demonstrated through the administration of various concentrations of state-of-the-art methanogenesis inhibitors. These inhibitors include lyophilized Asparagopsis taxiformis (AT), bromoform (BF), iodoform (IF), 3-nitrooxypropanol (3-NOP), rapeseed oil, and BF dissolved in rapeseed oil, with maximum CH4 reductions of 96.29% (p = 5.00E-05, Cohen’s d = 30.29), 98.22% (p = 2.88E-05, d = 23.07), 96.26% (p = 1.03E-05, d = 30.29), 74.63% (p = 8.88E-05, d = 13.32), 28.96% (p = 0.001, d = 3.99), and 98.51% (p = 4.18E-06, d = 39.94), respectively, in comparison to the negative control. The gas production dynamics in our setup align with previously published results, which supports the validity of the system. Compared to conventional methodologies, the described setup offers enhanced versatility and ease of use. Furthermore, Fourier-transform-infrared-spectroscopy is implemented in a novel and low-cost approach for quantifying CH₄ and CO₂ in the headspace gas. Together, these methodological advances provide an accessible and reproducible platform for long-term in vitro rumen cultivation for the screening of anti-methanogenic additives.