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Analysis of Body Parameters' Effects on Various Gaits in Locusts
No full textThis study investigates the relationship between morphological parameters and gait patterns in Bombay locusts ( ). Locusts exhibit unique morphology characterized by enlarged hind legs that distinguish them from other insects. This morphological specialization correlates with distinctive gait patterns not observed in other insect species. We measured nine morphological parameters in 36 adult locusts (18 males, 18 females) and analyzed their locomotion using high speed cameras. Results demonstrated significant sexual dimorphism, with females exhibiting larger dimensions across all measured parameters. Gait analysis revealed that both sexes predominantly utilized multi cycle gaits, with males displaying single cycle gaits more frequently than females. Statistical analysis confirmed body size significantly influences locomotor behavior in locusts. These findings provide valuable insights for biomimetic robotic design and enhance our understanding of morphology dependent locomotion in biological systems
Accuracy evaluation of two markerless motion capture systems for measurement of upper extremities: Kinect V2 and Captiv
No full textMotion capturing is a promising method to assess working postures and human movements and, therewith, the risk of musculoskeletal injuries that could occur while performing manual tasks in industrial settings. To obtain a reliable risk assessment, the motion capture system used has to accurately measure body postures adopted by the worker during the task. This study evaluates the accuracy to measure joint angles of upper extremities of two different motion capture systems, namely the Microsoft Kinect V2 and the Captiv system, for angles of upper extremities. For this purpose, an experimental study was conducted involving 12 subjects performing preset static postures and basic movements, including elbow flexion, shoulder flexion, and shoulder abduction. In addition, to examine whether self‐occlusion or occlusion of body parts by work equipment has an impact on the accuracy of the Kinect V2, the subjects handled boxes during some of the tests. As a gold standard, a goniometer for static and an angle scale for dynamic exercises was used. The Captiv system shows high correlation coefficients ( r > .93) and small mean absolute errors (<5°) for all movements except for elbow flexion. The Kinect V2 has sufficient results for joint angles captured without occlusion as well, but the accuracy significantly decreases when occlusion occurs
The Unique Ankle Articulation of Avimimus: Examining Its Potential Existence Through Robotic Modeling
No full textPalaeognaths, including ostriches and emus, comprise many large, terrestrial birds and are regarded as model animals for biomechanical studies of extinct dinosaurs, particularly theropods. A distinctive biomechanical feature of palaeognaths is a specialized mechanism in the intertarsal joint (one of the ankle joints), known as the engage-disengage mechanism (EDM). This passive mechanism is defined by a locally unstable equilibrium that emerges at a certain degree of flexion. It serves as a boundary between two locally stable equilibria: full extension and full flexion. The mechanism is facilitated by cam-like articular surfaces, a type of mechanical element, and is thought to contribute to efficient locomotion in palaeognaths. Avimimus, a small theropod and a member of Oviraptorosauria, exhibits osteological features resembling the intertarsal joint structure of modern birds. These features include the fusion of the tarsal bones with the tibia to form the tibiotarsus, and the fusion of the metatarsals with the tarsal bones to form the tarsometatarsus. Consequently, Avimimus is considered one of the most suitable taxa for examining whether the passive mechanisms observed in the intertarsal joints of extant birds could have also been present in non-avian dinosaurs. In this study, we investigate the potential existence of the EDM in dinosaurian ankle joints by constructing a physical model based on Avimimus specimens
Simple Cellular Automaton Model for Understanding Caterpillar Swarm Locomotion
No full textSawfly larvae form a multi-layered swarm and move collectively, like a single large caterpillar. It is suggested that they achieve faster collective movement than individual locomotion by utilizing each other as moving walkways or escalators, the behavior called rolling swarm. However, the behavior remains largely unknown, with many aspects, such as aggregation mechanism and motor control, yet to be fully investigated. Understanding this collective mechanism provides valuable insights into animal swarm systems and establishing a design principle for soft swarm robots. This study investigated aggregation mechanisms underlying rolling swarm via mathematical modeling and simulations. We hypothesized that physical interactions between individual caterpillars help form a rolling swarm. Caterpillars riding on another seem to move faster, and the others being ridden on move slowly. This interaction causes a velocity differential between the upper and lower layers and contributes to aggregation. We developed a simple cellular automaton model to verify the hypothesis and succeeded in reproducing a similar behavior that enhanced speed and climbing ability over rough terrain. These results suggest that local information via physical interactions between individuals can form an adaptive swarm behavior
Spatiotemporal Measurement of Osmotic Pressures by FRET Imaging
No full textOsmotic pressures (OPs) play essential roles in biological processes and numerous technological applications. However, the measurement of OP in situ with spatiotemporal resolution has not been achieved so far. Herein, we introduce a novel kind of OP sensor based on liposomes loaded with water‐soluble fluorescent dyes exhibiting resonance energy transfer (FRET). The liposomes experience volume changes in response to OP due to water outflux. The FRET efficiency depends on the average distance between the entrapped dyes and thus provides a direct measure of the OP surrounding each liposome. The sensors exhibit high sensitivity to OP in the biologically relevant range of 0–0.3 MPa in aqueous solutions of salt, small organic molecules, and macromolecules. With the help of FRET microscopy, we demonstrate the feasibility of spatiotemporal OP imaging, which can be a promising new tool to investigate phenomena involving OPs and their dynamics in biology and technology
Studies on the validity of the reduced bending stiffness method for eccentrically stacked laminates
No full textThe reduced bending stiffness method is used in the framework of computational models for stringer stiffened panels. Here, the stringer foot is often stacked on top of the skin of the panel and leads to a stacked laminate with extensional bending stiffness coupling. The validity of the reduced bending stiffness method for the mentioned laminate type is investigated and assessed, as only unsymmetrical laminates without eccentricity have been considered in existing literature. In exemplary studies, the influence of the coupling effects is shown, which allows drawing conclusions on the error that is introduced in, e. g. closed‐form analytical approximate solutions for the buckling of stringer stiffened panels
Buckling analysis of elastically clamped laminated plates using third‐order shear deformation theory
No full textThis paper considers the buckling of transverse shear‐deformable orthotropic laminated plates under uniaxial compression, which is modeled with the third‐order shear deformation theory (TSDT). The consideration of transverse shear deformation is relevant for plates with small transverse shear stiffness or small length to thickness ratio. The supporting effect of the surrounding structure is represented by laterally attached rotational restraints. The present analysis approach uses a simple energy‐based formulation in the form of a Rayleigh‐quotient for which specific shape functions for the out‐of‐plane buckling deformations as well as for the rotational degrees of freedom are employed. A comparison of the results with the Lévy‐type solution shows that the analysis approach works with satisfying accuracy, thus making it suitable for engineering analysis of plates with arbitrary thickness especially when computational time and effort are essential factors
2-Deoxy-D-Glucose and ES-936 sensitize cancer- but not normal cells to both low- and high LET irradiation
No full textIntroduction: Metabolic differences of normal- and cancer cells represent an important target for the development of novel cancer treatment strategies. Given that radiotherapy constitutes one of the primary treatment modalities for solid cancers, the targeting of cancer cell metabolism to enhance their sensitivity to irradiation emerges as a promising approach. The utilization of glycolysis even under aerobic conditions in cancer cells presents a unique target to deprive cancer cells of energy and metabolites required not only for their rapid cell growth but also for the repair of irradiation induced DNA damage. Furthermore, cancer cells have been observed to exhibit elevated levels of reactive oxygen species and potentially react more sensitively to an induced disturbance of the redox balance, especially after irradiation mediated oxidative stress. Overall, interference with aerobic glycolysis and the oxidative stress response could potentiate the anti-proliferative and cytotoxic effects of cancer cell irradiation, while sparing normal cells.
Methods: To analyze the effect of inhibitors targeting the cellular metabolism and redox balance, normal fibroblast- and cancer cell lines were characterized using a Seahorse XFp metabolic analyzer, followed by Sulforhodamin B proliferation assays and flow cytometry based cell cycle analysis. Furthermore, NADP+/NADPH-, NAD(P)H- and ROS levels were determined using bioluminescent assays, Fluorescence Lifetime Imaging Microscopy (FLIM) and fluorescent microscopy. Radiosensitization of cell lines was assessed through clonogenic survival assays and analyses of DNA-repair efficiency via fluorescence microscopy.
Results: The present study demonstrates that the glycolytic inhibitor 2-deoxy-D-glucose and the NAD(P)H:quinone oxidoreductase inhibitor ES-936 can render cancer cells more sensitive to X-rays and densely ionizing radiation (high-linear energy transfer (LET) irradiation) like alpha-particles or heavy ions but do not affect normal fibroblasts. While inhibitor-treated and low-LET (X-ray) irradiated cancer cells exhibited a decreased clonal survival, an additional DNA repair defect was observed after high-LET irradiation.
Discussion: Our results imply that distinct mechanisms influence the clonal survival and DNA repair of irradiated, inhibitor-treated cancer cells in dependence of the LET. The findings of this study suggest that the combination of inhibitors targeting glycolysis and the redox balance may represent a promising strategy to enhance the sensitivity of cancer cells to both photon- and charged particle therapy
Solid-state polycyclotrimerization of diynes to porous organic polymers
No full textHerein, we report a solid-state polycyclotrimerization of 1,4-diethynylbenzene using mechanochemical activation in a ball mill, yielding a highly porous and hydrophobic hyperbranched polymer (HBP) with a specific surface area of up to 570 m² g⁻¹. The reaction, catalyzed by Fe(hmds)2 and conducted under solvent-free conditions, was optimized by varying milling time and frequency. This method enables the efficient synthesis of insoluble, porous organic polymers with high yields (up to 95%) and offers an environmentally friendly alternative to traditional solution-based polymerizations
