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Surface tension behavior of superspreading and non-superspreading trisiloxane surfactants
No full textOne parameter frequently considered to be relevant for superspreading of trisiloxane surfactants is surface tension kinetics. In the scientific literature, some experimental results reported for trisiloxane surfactants are in contradiction with fundamental concepts of surfactant monomer diffusion. Therefore, maximum bubble pressure tensiometry has been used to determine dynamic surface tension (DST) of two types of trisiloxane surfactants: superspreader and non-superspreader. Results show that both surfactants behave similarly at concentrations below critical micelle concentration (CMC), as expected. The CMC curves, as determined by drop shape analysis, confirmed that the more hydrophilic non-superspreader has a higher CMC as compared to the more hydrophobic superspreader. Accordingly, the lower surfactant monomer concentration of the superspreader results in a higher DST than the non-superspreader at the same surface age. So, in contrary to claims in the literature, there is nothing mysterious or unexpected concerning the surface tension behavior of trisiloxane surfactants
Temporally consistent sequence-to-sequence translation of cataract surgeries
No full textPurpose: Image-to-image translation methods can address the lack of diversity in publicly available cataract surgery data. However, applying image-to-image translation to videos—which are frequently used in medical downstream applications—induces artifacts. Additional spatio-temporal constraints are needed to produce realistic translations and improve the temporal consistency of translated image sequences.
Methods: We introduce a motion-translation module that translates optical flows between domains to impose such constraints. We combine it with a shared latent space translation model to improve image quality. Evaluations are conducted regarding translated sequences’ image quality and temporal consistency, where we propose novel quantitative metrics for the latter. Finally, the downstream task of surgical phase classification is evaluated when retraining it with additional synthetic translated data.
Results: Our proposed method produces more consistent translations than state-of-the-art baselines. Moreover, it stays competitive in terms of the per-image translation quality. We further show the benefit of consistently translated cataract surgery sequences for improving the downstream task of surgical phase prediction.
Conclusion: The proposed module increases the temporal consistency of translated sequences. Furthermore, imposed temporal constraints increase the usability of translated data in downstream tasks. This allows overcoming some of the hurdles of surgical data acquisition and annotation and enables improving models’ performance by translating between existing datasets of sequential frames
On Modified Halpern and Tikhonov–Mann Iterations
No full textWe show that the asymptotic regularity and the strong convergence of the modified Halpern iteration due to T.-H. Kim and H.-K. Xu and studied further by A. Cuntavenapit and B. Panyanak and the Tikhonov–Mann iteration introduced by H. Cheval and L. Leuştean as a generalization of an iteration due to Y. Yao et al. that has recently been studied by Boţ et al. can be reduced to each other in general geodesic settings. This, in particular, gives a new proof of the convergence result in Boţ et al. together with a generalization from Hilbert to CAT(0) spaces. Moreover, quantitative rates of asymptotic regularity and metastability due to K. Schade and U. Kohlenbach can be adapted and transformed into rates for the Tikhonov–Mann iteration corresponding to recent quantitative results on the latter of H. Cheval, L. Leuştean and B. Dinis, P. Pinto, respectively. A transformation in the converse direction is also possible. We also obtain rates of asymptotic regularity of order O(1/n) for both the modified Halpern (and so in particular for the Halpern iteration) and the Tikhonov–Mann iteration in a general geodesic setting for a special choice of scalars
Application of nickel-doped graphene nanotubes to modified GCE as a sensitive electrochemical sensor for the antipsychotic drug clozapine in spiked human blood serum samples
No full textClozapine (CLZ) is one of the most vital medications for managing schizophrenia, and the timely measurement of CLZ levels has been recognized as an obstacle to the wider use of CLZ. Herein, for the first time, nickel-doped graphene nanotubes (Ni@GRNT) were used to construct an electrochemical CLZ sensor by drop coating Ni@GRNT suspension on a glassy carbon electrode. The Ni@GRNT was synthesized and characterized using X‐ray diffraction, scanning electron microscopy, and energy-dispersive X-ray spectroscopy. The electrochemical behavior and influence of different physicochemical factors of sensing electrodes were investigated by using cyclic voltammetry, EIS technique, and differential pulse voltammetry techniques. Also, the catalytic rate constant (kcat) and the transfer coefficient (α) were calculated. The modified electrode illustrated satisfactory linear range, detection limit (LOD), reusability, and reproducibility results. At optimal experimental conditions, measurements can be performed at a broad linear dynamic range of 0.3 nmol L⁻¹–60.0 μmol L⁻¹ CLZ and with a LOD of 0.1 nmol L⁻¹. The sensitivity value was estimated to be 3.06 μA µmol L⁻¹ cm⁻². Ultimately, this platform was successfully used for CLZ sensing in spiked human blood serum and tablet samples with an accuracy of > 93%
Stabilization of spline bases by extension
No full textWe present a method to stabilize bases with local supports by means of extension. It generalizes the known approach for tensor product B-splines to a much broader class of functions, which includes hierarchical and weighted variants of polynomial, trigonometric, and exponential splines, but also box splines, T-splines, and other function spaces of interest with a local basis. Extension removes elements that cause instabilities from a given basis by linking them with the remaining ones by means of a specific linear combination. The two guiding principles for this process are locality and persistence. Locality aims at coupling basis functions whose supports are close together, while persistence guarantees that a given set of globally supported functions, like certain monomials in the case of polynomial splines, remain in the span of the basis after extension. Furthermore, we study how extension influences the approximation power and the condition of Gramian matrices associated with the basis, and present a series of examples illustrating the potential of the method
Risikotechnologien in europäischen Mediendiskursen : Der korpuslinguistische Zugriff am Beispiel „Biotechnologie“
Get PDFIn diesem Beitrag wird exemplarisch vorgeführt, wie sprachstatistische Verfahren, die im Rahmen der sog. „Korpuslinguistik“ entwickelt werden, im Bereich der Risikoforschung eingesetzt werden können. Es wird gezeigt, wie einzelne Technologien in Medientexten als Risiken thematisiert werden und was daraus jeweils für die Konzeptualisierung von „Risiko“ folgt. Korpuslinguistische Verfahren ermöglichen einen großflächigen Zugriff auf sprachliche Ordnungsmuster, die mit der entsprechenden Heuristik als Spuren begrifflich gefasster Perspektiven auf Sachverhalte interpretiert werden können. Beispielhaft werden im folgenden Beitrag Korpusdaten zur Wahrnehmung von Grüner Gentechnik als Risikotechnologie aus der deutschen, englischen und italienischen Presse dargestellt. Dabei zeigt sich, dass der Risikobegriff jeweils Eigenheiten aufweist, die sich in einer je spezifischen Überlagerungssituation von nationalen Bewertungstraditionen und der je thematischen Technologie formieren. Durch den Einsatz der Korpuslinguistik lassen sich kollektive Einstellungen und Denkmuster zu Risiken nicht nur erahnen und am Einzelfall zeigen, sondern in ihrem Ausmaß und ihrer gesellschaftlichen Relevanz im Wortsinne ermessen. Auf diese Weise lassen sich verlässliche Daten über die Einstellung öffentlicher Akteure zu Risikotechnologien erheben und als Basis für gesellschaftliche, wissenschaftliche und politische Beratungen fruchtbar machen
Introducing the double validation metric for radar sensor models
No full textIn automated vehicles, environment perception is performed by various sensor types, such as cameras, radars, lidars, and ultrasonics. Simulation models of these sensors, as required in virtual validation methods, are available in various degrees of detail. However, proving the validity of such models is a subject of research. New metrics and methods for credibility assessment of simulation are needed to standardize the validation process in the future. The so-called double validation metric (DVM) has shown advantages and allows an intuitive interpretability of the validation results. The DVM has so far only been applied to lidar sensor models. In this paper, an extension to the DVM is introduced, which is called the DVM Map. A static measurement scenario is conducted in reality and transferred into simulation. The novel method is demonstrated on the obtained real and simulated radar sensor data. In this simple scenario special focus is put on the position accuracy of GNSS reference sensors. Therefore, their impact on the result of sensor model validation is discussed. The paper shows that the method provides a more detailed and accurate validation in comparison to the state of the art of a radar simulation, revealing previously undetected simulation errors. Errors due to the environment model, signal propagation, and signal processing are separated and satellite imagery is used for intuitive visualization of the results. This method is a complementary tool to existing validation techniques to improve the interpretability and judging the trustworthiness of radar simulations
Uptake of substances into living mammalian cells by microwave induced perturbation of the plasma membrane
Get PDFDelivering foreign molecules and genetic material into cells is a crucial process in life sciences and biotechnology, resulting in great interest in effective cell transfection methods. Importantly, physical transfection methods allow delivery of molecules of different chemical composition and are, thus, very flexible. Here, we investigated the influence of microwave radiation on the transfection and survival of mammalian cells. We made use of an optimized microwave-poration device and analyzed its performance (frequency and electric field strength) in comparison with simulations. We, then, tested the effect of microwave irradiation on cells and found that 18 GHz had the least impact on cell survival, viability, cell division and genotoxicity while 10 GHz drastically impacted cell physiology. Using live-cell fluorescence microscopy and image analysis, we tested the uptake of small chemical substances, which was most efficient at 18 GHz and correlated with electric field strength and frequency. Finally, we were able to obtain cellular uptake of molecules of very different chemical composition and sizes up to whole immunoglobulin antibodies. In conclusion, microwave-induced poration enables the uptake of widely different substances directly into mammalian cells growing as adherent cultures and with low physiological impact
Soil Indigenous Microbes Interact with Maize Plants in High-Arsenic Soils to Limit the Translocation of Inorganic Arsenic Species to Maize Upper Tissues
Get PDFArsenic (As) is a toxic metalloid that can enter the food chain through uptake by plants from soils followed by production of plant-based food. While soil–plant transfer of As in crops, especially rice, is relatively well studied, the role of soil microbes in As translocation in maize is not well understood. We performed a greenhouse pot experiment with maize plants grown at different soil As levels to study the role of soil microbes on uptake of different As species by maize. Three soil treatments with varying disturbance of the soil microbes (native soil, sterilized soil, and sterilized soil reconditioned with soil indigenous microbes) were intersected with three levels of As in soils (0, 100 and 200 mg kg⁻¹ spiked As, aged for 8 weeks) in a greenhouse experiment, where maize was grown for 5 months. Compared to uncontaminated soils, maize in high-As soils tended to accumulate more As in stems and less in leaves and grains, proportionally. Arsenic levels in stems were increased in sterilized soils due to the disturbance of the microbiome. The sterilization effects caused a phosphorus and manganese deficiency, leading to a higher As uptake in plants, that increased with rising As levels and resulted in a lower total dry biomass of the plants. In summary, this study highlights the role of soil indigenous microbes in limiting the uptake and translocation of inorganic As into maize. Compared to rice, cultivating maize plants in high-As soils is recommended
Safe hierarchical model predictive control and planning for autonomous systems
Get PDFPlanning and control for autonomous vehicles usually are hierarchically separated. However, increasing performance demands and operating in highly dynamic environments requires a frequent re-evaluation of the planning and tight integration of control and planning to guarantee safety, performance, and reliability. We propose an integrated hierarchical predictive control and planning approach to tackle this challenge. The planner and controller are based on repeated solutions of moving horizon optimal control problems. To increase flexibility and feasibility, the planner can choose different low-layer controller modes for increased flexibility and performance instead of using a single controller with a large safety margin for collision avoidance under uncertainty. Planning is based on simplified system dynamics and safety, yet flexible operation is ensured by constraint tightening based on a mixed-integer linear programming formulation. A cyclic horizon tube-based model predictive controller guarantees constraint satisfaction for different control modes and disturbances. Examples of different modes are slow-speed movement with high precision and fast-speed movements with large uncertainty bounds. Allowing for different control modes reduces conservatism, while the hierarchical decomposition of the problem reduces the computational cost and enables real-time implementation. We derive conditions for recursive feasibility to ensure constraint satisfaction and obstacle avoidance to guarantee safety and compatibility between the layers and modes. Simulation results illustrate the efficiency and applicability of the proposed hierarchical strategy