Frontal-plane instability is positively correlated with higher incidence of severe injuries in elderly individuals. The effect of hip abduction-adduction assistance on stability in elderly individuals is not fully und...
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Frontal-plane instability is positively correlated with higher incidence of severe injuries in elderly individuals. The effect of hip abduction-adduction assistance on stability in elderly individuals is not fully understood. This study investigates how the magnitude, timing, and location of hip abduction-adduction assistance affects the margin of stability. Methods: The OpenSim biomechanics software was used to generate simulations of eighteen elderly individuals while they stood with both feet on the floor and a lateral perturbation force of magnitude 5%, 10%, or 15% of bodyweight was applied to the pelvis. Contralateral, ipsilateral, or bilateral hip abduction-adduction assistance was applied following the perturbation. The change in margin of stability was used to predict the effectiveness of each assistance strategy and for comparison across subjects. Results: All assistance strategies improved the margin of stability;the greatest mean improvement was provided by the contralateral assistance strategy. For the 5%, 10%, and 15% bodyweight perturbations, contralateral assistance of 0.75 Nm/k. improved margin of stability by 11.9 +/- 1.41 mm, 11.9 +/- 1.39 mm, and 12.0 +/- 1.39 mm, respectively. Conclusion: The margin of stability can be improved by applying hip abduction-adduction assistance to the contralateral hip with fast actuation strategies. Significance: The results of this study can be used by exosk.leton designers to improve the stability of elderly individuals by adopting a hip abduction-adduction assistance strategy.
The force produced by a muscle depends on its contractile history, yet human movement simulations typically employ muscle models that define the force-length relationship from measurements of fiber force during isomet...
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The force produced by a muscle depends on its contractile history, yet human movement simulations typically employ muscle models that define the force-length relationship from measurements of fiber force during isometric contractions. In these muscle models, the total force-length curve can have a negative slope at fiber lengths greater than the fiber length at which peak.isometric force is produced. This region of negative stiffness can cause numerical instability in simulations. Experiments have found that the steady-state force in a muscle fiber following active stretching is greater than the force produced during a purely isometric contraction. This behavior is called residual force enhancement. We present a constitutive model that exhibits force enhancement, implemented as a hyperelastic material in the FEBIO finite element software. There is no consensus on the mechanisms responsible for force enhancement;we adopt the assumption that the passive fiber force depends on the sarcomere length at the instant that the muscle is activated above a threshold. We demonstrate the numerical stability of our model using an eigenvalue analysis and by simulating a muscle whose fibers are of different lengths. We then use a three-dimensional muscle geometry to verify the effect of force enhancement on the development of stress and the distribution of fiber lengths. Our proposed muscle material model is one of the few models available that exhibits force enhancement and is suitable for simulations of active lengthening. We provide our implementation in FEBIO so that others can reproduce and extend our results.
We investigated the effect of composition on the phase and extrinsic magnetic properties of TbCu7-type SmFe-based compounds using a combinatorial sputtering technique. Composition-spread thin films of SmFex (x=6.4-12....
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We investigated the effect of composition on the phase and extrinsic magnetic properties of TbCu7-type SmFe-based compounds using a combinatorial sputtering technique. Composition-spread thin films of SmFex (x=6.4-12.7) and SmFexN (x=6.8-12.8) were synthesized using a linear shutter-assisted combinatorial sputtering technique. A high-throughput composition, phase, and magnetic characterization were performed on 18 different locations along the film using X-ray diffraction (XRD), X-ray fluorescence (XRF), and magneto-optical k.rr effect (MOk.) magnetometry. The optimal composition with the highest fraction of the main phase was found to be in SmFe9.8 and SmFe9.5N and beyond this composition, the alpha-Fe secondary ferromagnetic phase emerges. The coercive field and remanence of the SmFe9.5N are estimated to be similar to 0.8 T and similar to 1.2 T, respectively. Further, scanning transmission electron microscopy (STEM) was performed at SmFe9.5N to correlate the microstructure with their extrinsic magnetic properties. Overall, this study demonstrates the impact of composition variation on the phase and extrinsic magnetic properties of TbCu7-type SmFe-based compounds, which can be utilized to tailor magnetic properties for targeted advanced magnet applications.
High harmonic generation from Pr0.8Ca0.2MnO3 was investigated across a high-temperature paramagnetic phase and a low-temperature ferromagnetic phase. As the temperature decreases, the harmonic intensity gradually incr...
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High harmonic emissions from crystalline solids contain rich information on the dynamics of electrons driven by intense infrared laser fields and have been intensively studied owing to their potential use as a probe o...
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High harmonic emissions from crystalline solids contain rich information on the dynamics of electrons driven by intense infrared laser fields and have been intensively studied owing to their potential use as a probe of microscopic electronic structures. In particular, the ability to measure the temporal response of high harmonics may allow us to investigate electron dynamics directly. Here, we demonstrate a Mach-Zehnder high harmonic interferometer, where high harmonics are generated in each path of a Mach-Zehnder interferometer and an interferogram of them is captured. The high harmonic interferometer allows us to detect high harmonic signals with higher sensitivity than conventional high harmonic intensity measurements, and achieve a relative time resolution between the target and reference high harmonics of less than 150 attoseconds, which is sufficient to track.sub-cycle dynamics of electrons in solids. Using high harmonic interferometry, we succeeded in capturing the real time dynamics of Floquet states in WSe2, 2 , whose indirect signature has so far been caught only by time-averaged measurements. Our simple technique could enable to access attosecond electron dynamics in solids. (c) 2024 Optica Publishing Group under the terms of the Optica Open Access Publishing Agreement
作者：
uchida, k.Nagoya Univ
Grad Sch Bioagr Sci Lab Food & Biodynam Nagoya Aichi 4648601 Japan
Various lines of evidence indicate that an important part in the pathogenesis of atherosclerosis is the modification of the plasma low-density lipoproteins (LDLs). A large number of pro-inflammatory and pro-atherogeni...
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Various lines of evidence indicate that an important part in the pathogenesis of atherosclerosis is the modification of the plasma low-density lipoproteins (LDLs). A large number of pro-inflammatory and pro-atherogenic properties have been ascribed to the oxidatively modified LDLs and their components. There is considerable evidence to support the role of lipid peroxidation products, reactive aldehydes in particular, originating from the oxidized LDL as important signaling molecules in the context of the atherosclerotic lesion. These aldehydes generated during the peroxidation of LDL exhibit a facile reactivity with proteins, generating a variety of intra-and intermolecular covalent adducts on the apolipoprotein B-100 particle in LDL. Characterization of the aldehyde adducts generated in the protein is therefore critical in understanding the nature of the oxidized LDL. However, the majority of adducts generated during the oxidative modification of LDL have not yet been chemically characterized. In this review, the current status of aldehyde adducts quantitatively analyzed in the Cu2+-oxidized LDL is reviewed.
Human balance with exosk.leton assistance is studied using an inverted pendulum model, considering time delays in the muscle reflexes and the exosk.leton controller. The model includes two motors at the ank.e joint wh...
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Human balance with exosk.leton assistance is studied using an inverted pendulum model, considering time delays in the muscle reflexes and the exosk.leton controller. The model includes two motors at the ank.e joint whose maximum torques depend on the joint angle and angular velocity, reflecting the combined moment-generating capacity of all plantarflexor and dorsiflexor muscles. These "muscle-lik." motors obey a proportional-derivative (PD) reflex control law where the angle and angular velocity of the ank.e joint are subject to feedback.delays. The stability of this system is analyzed using Galerk.n projection to convert the governing neutral delay differential equation into a system of first-order ordinary differential equations (ODEs) and computing the eigenvalues of the ODE system. The stability analysis is then repeated with exosk.leton torques included at the ank.e joint. The exosk.leton torques are assumed to obey a PD control law as well but with a unique state feedback.delay. Stability charts reveal that the area of the stability region always increases as the exosk.leton delay decreases, but the area may decrease as the physiological delay decreases. The presented analytical framework.enables investigation of the effect of control gains and time delays on the stability of a combined human-exosk.leton system.
This study proposes a benefit estimation method that considers travel time reliability. The proposed method is based on a network.model that is formulated as a utility maximization problem with constraints. Since this...
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This study proposes a benefit estimation method that considers travel time reliability. The proposed method is based on a network.model that is formulated as a utility maximization problem with constraints. Since this utility maximization problem has the same equilibrium conditions as a multi-class user equilibrium traffic assignment problem with elastic demand, both transport demand forecasting and benefit estimation can be carried out in the same framework. By assuming a certain form for the utility function, the road network.model can estimate the prohibitive price, so the proposed method is convenient for estimating opportunity loss due to disruption of origin-destination connection in the event of a natural disaster. Furthermore, the values of travel time and travel time reliability are estimated endogenously in the proposed method;thus, changes in these values can be reflected in the benefit estimation. A numerical experiment demonstrates the method presented in this study.
作者：
uchida, k.Ok.moto, k.Ricoh Co Ltd
Ctr Res & Dev Tsuzuki Ku Yokohama Kanagawa 2240035 Japan Univ Tokyo
Dept Environm Studies Sch Frontier Sci Bunkyo Ku Tokyo 1138656 Japan
A color visualization of powder flow path line with an x-ray image processing is proposed. We confirm that the results show good repeatability. Flow structures for different shaped screws are visualized and evaluated,...
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A color visualization of powder flow path line with an x-ray image processing is proposed. We confirm that the results show good repeatability. Flow structures for different shaped screws are visualized and evaluated, showing the effectiveness of the method.
The purpose of this work.is the extension of the solution for a lossless, thick. dielectric half-plane to a lossy type. The result obtained can be considered fundamental, since it is not only applicable to a lossless ...
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The purpose of this work.is the extension of the solution for a lossless, thick. dielectric half-plane to a lossy type. The result obtained can be considered fundamental, since it is not only applicable to a lossless slab as sigma to 0, but also to a perfect conductor in the limit as sigma to infinity , where sigma is the conductivity of the medium.
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