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Critical torque

Hyunglae Lee, Elliott J Rouse, Hermano Igo Krebs
The human ankle joint plays a critical role during walking and understanding the biomechanical factors that govern ankle behavior and provides fundamental insight into normal and pathologically altered gait. Previous researchers have comprehensively studied ankle joint kinetics and kinematics during many biomechanical tasks, including locomotion; however, only recently have researchers been able to quantify how the mechanical impedance of the ankle varies during walking. The mechanical impedance describes the dynamic relationship between the joint position and the joint torque during perturbation, and is often represented in terms of stiffness, damping, and inertia...
2016: IEEE Journal of Translational Engineering in Health and Medicine
M V Rasna, K P Zuhail, U V Ramudu, R Chandrasekar, Surajit Dhara
We study the dynamics of electric field driven multiaxis electro-orientation of birefringent microsheets in both the isotropic and nematic phases of a liquid crystal. For a fixed direction of applied field in the isotropic phase, there are two critical fields above which the microsheets show two orientations. In the nematic phase, it shows three rotations in both planar and homeotropic cells. These orientations are observed at varying voltages and wide time scales and are explained based on the competing effect of the electric, elastic, and viscous torques...
September 2016: Physical Review. E
E Eisenriegler, T W Burkhardt
We consider the fluctuation-induced interaction of two thin, rodlike particles, or "needles," immersed in a two-dimensional critical fluid of Ising symmetry right at the critical point. Conformally mapping the plane containing the needles onto a simpler geometry in which the stress tensor is known, we analyze the force and torque between needles of arbitrary length, separation, and orientation. For infinite and semi-infinite needles we utilize the mapping of the plane bounded by the needles onto the half plane, and for two needles of finite length we use the mapping onto an annulus...
September 2016: Physical Review. E
Lorena Maldonado-Camargo, Carlos Rinaldi
We report observations of breakdown of the Stokes-Einstein relation for the rotational diffusivity of polymer-grafted spherical nanoparticles in polymer melts. The rotational diffusivity of magnetic nanoparticles coated with poly(ethylene glycol) dispersed in poly(ethylene glycol) melts was determined through dynamic magnetic susceptibility measurements of the collective rotation of the magnetic nanoparticles due to imposed time-varying magnetic torques. These measurements clearly demonstrate the existence of a critical molecular weight for the melt polymer, below which the Stokes-Einstein relation accurately describes the rotational diffusivity of the polymer-grafted nanoparticles and above which the Stokes-Einstein relation ceases to apply...
October 11, 2016: Nano Letters
Marco Schieppati, Jean Louis Honeine, Manh-Cuong Do, Oscar Crisafulli
OBJECTIVE: The critical action for gait initiation involves lifting of the swing leg while shifting the centre of mass (CoM) of the body over the stance leg. This action is made possible by the initial displacement of the centre of pressure (CoP) in the direction of the swing leg. We hypothesised that the CoP displacement requires a coordinated action of the swing-leg abductor muscles and of the dorsiflexor muscles of the stance leg. MATERIAL/PATIENTS AND METHODS: Nine subjects initiated gait starting from three different initial stance widths (small, medium, wide)...
September 2016: Annals of Physical and Rehabilitation Medicine
Z Yan, J Jin, W J Feng
In this paper, a model of torque dependence of critical current in a Bi2223/Ag composite concentric cylinder is analyzed. Based on the hypothesis of planar section and elastic linear strengthening constitutive theory, the relation between torque and shear strain is firstly obtained. Then a linear weakening relation between critical current density and shear strain are put forward. Finally the effects of the applied torque together with the mechanical properties of superconducting core on the degradation behavior of critical current are calculated and discussed...
2016: SpringerPlus
Vegard Flovik, Ferran Macià, Erik Wahlström
The collective dynamics in populations of magnetic spin torque oscillators (STO) is an intensely studied topic in modern magnetism. Here, we show that arrays of STO coupled via dipolar fields can be modeled using a variant of the Kuramoto model, a well-known mathematical model in non-linear dynamics. By investigating the collective dynamics in arrays of STO we find that the synchronization in such systems is a finite size effect and show that the critical coupling-for a complete synchronized state-scales with the number of oscillators...
2016: Scientific Reports
Jiahao Han, Yuyan Wang, Feng Pan, Cheng Song
Antiferromagnet (AFM) spintronics with reduced electrical current is greatly expected to process information with high integration and low power consumption. In Pt/FeMn and Ta/FeMn hybrids, we observe significant resistance variation (up to 7% of the total resistance) manipulated by 10(5) A/cm(2) dc current. We have excluded the contribution of isotropic structural effects, and confirmed the critical role of the spin Hall injection from Pt (or Ta) to FeMn. This electrical current-manipulated resistance (i...
2016: Scientific Reports
Hossein Rouhani, Milos R Popovic, Michael Same, Ya Qi Li, Kei Masani
Modeling the muscle response to functional electrical stimulation (FES) is an essential step in the design of closed-loop controlled neuroprostheses. This study was aimed at identifying the dynamic response of ankle plantar-flexors to FES during quiet standing. Thirteen healthy subjects stood in a standing frame that locked the knee and hip joints. The ankle plantar-flexors were stimulated bilaterally through surface electrodes and the generated ankle torque was measured. The pulse amplitude was sinusoidally modulated at five different frequencies...
August 17, 2016: Medical Engineering & Physics
V Vanhoorne, L Janssens, J Vercruysse, T De Beer, J P Remon, C Vervaet
HPMC is a popular matrix former to formulate tablets with extended drug release. Tablets with HPMC are preferentially produced by direct compression. However, granulation is often required prior to tableting to overcome poor flowability of the formulation. While continuous twin screw granulation has been extensively evaluated for granulation of immediate release formulations, twin screw granulation of controlled release formulations including the dissolution behavior of the formulations received little attention...
September 25, 2016: International Journal of Pharmaceutics
Marco Laubacher, Efe A Aksöz, Stuart Binder-Macleod, Kenneth J Hunt
Spatially distributed sequential stimulation (SDSS) has demonstrated substantial power output and fatigue benefits compared to single electrode stimulation (SES) in the application of functional electrical stimulation (FES). This asymmetric electrode setup brings new possibilities but also new questions since precise placement of the electrodes is one critical factor for good muscle activation. The aim of this study was to compare the power output, fatigue and activation properties of proximally versus distally placed SDSS electrodes in an isokinetic knee extension task simulating knee movement during recumbent cycling...
June 13, 2016: European Journal of Translational Myology
Woosun Jang, Kisung Kang, Aloysius Soon
Many different forms of mechanical and structural deformations have been employed to alter the electronic structure of various modern two-dimensional (2D) nanomaterials. Given the recent interest in the new class of 2D nanomaterials - phosphorene, here we investigate how the rotational strain-dependent electronic properties of low-dimensional phosphorene may be exploited for technological gain. Here, using first-principles density-functional theory, we investigate the mechanical stability of twisted one-dimensional phosphorene nanoribbons (TPNR) by measuring their critical twist angle (θc) and shear modulus as a function of the applied mechanical torque...
August 4, 2016: Nanoscale
Nicole C Dabbs, Christopher D Black, John C Garner
Determining muscle contractile properties following exercise is critical in understanding neuromuscular function. Following high intensity training, individuals often experience exercise induced muscle damage (EIMD). The purpose of this investigation was to determine the effect of whole-body vibration (WBV) on muscle contractile properties following EIMD. Twenty-seven females volunteered for 7 sessions and were randomly assigned to a treatment or control group. Muscle contractile properties were assessed via voluntary torque (VT), peak twitch torque (TT), time to reach peak torque, half relaxation time of twitch torque, percent activation (%ACT), rate of rise (RR), rate of decline (RD), mean and peak electromyography during maximum voluntary isometric contraction...
October 2016: Journal of Electromyography and Kinesiology
Maurizio Vannoni, Idoia Freijo Martín, Harald Sinn
One of the classical devices used to tune a mirror on an X-ray optical setup is a mechanical bender. This is often designed in such a way that the mirror is held with clamps on both ends; a motor is then used to put a torque on the clamps, inducing a cylindrical shape of the mirror surface. A mechanical bender with this design was recently characterized, to bend a 950 mm-long mirror up to a radius of curvature of 10 km. The characterization was performed using a large-aperture Fizeau interferometer with an angled incidence setup...
July 2016: Journal of Synchrotron Radiation
Yupeng Ren, Yi-Ning Wu, Chung-Yong Yang, Tao Xu, Richard Harvey, Li-Qun Zhang
Ankle movement training is important in motor recovery post stroke and early intervention is critical to stroke rehabilitation. However, acute stroke survivors receive motor rehabilitation in only a small fraction of time, partly due to the lack of effective devices and protocols suitable for early in-bed rehabilitation. Considering the first few months post stroke is critical in stroke recovery, there is a strong need to start motor rehabilitation early, mobilize the ankle, and conduct movement therapy. This study seeks to address the need and deliver intensive passive and active movement training in acute stroke using a wearable ankle robotic device...
June 22, 2016: IEEE Transactions on Neural Systems and Rehabilitation Engineering
Jennifer A Nichols, Michael S Bednar, Wendy M Murray
The utility of biomechanical models and simulations to examine clinical problems is currently limited by the need for extensive amounts of experimental data describing how a given procedure or disease affects the musculoskeletal system. Methods capable of predicting how individual biomechanical parameters are altered by surgery are necessary for the efficient development of surgical simulations. In this study, we evaluate to what extent models based on limited amounts of quantitative data can be used to predict how surgery influences muscle moment arms, a critical parameter that defines how muscle force is transformed into joint torque...
2016: PloS One
Brice Gabrielle, Emmanuel Gomez, Jean-Pierre Korb
We present improved analyses of rheometric torque measurements as well as (1)H double-quantum (DQ) nuclear magnetic resonance (NMR) buildup data on polymer networks of industrial compounds. This latter DQ NMR analysis allows finding the distribution of an orientation order parameter (Dres) resulting from the noncomplete averaging of proton dipole-dipole couplings within the cross-linked polymer chains. We investigate the influence of the formulation (filler and vulcanization systems) as well as the process (curing temperature) ending to the final polymer network...
June 23, 2016: Journal of Physical Chemistry. B
Yanjun Xu, Yumeng Yang, Kui Yao, Baoxi Xu, Yihong Wu
Extensive efforts have been devoted to the study of spin-orbit torque in ferromagnetic metal/heavy metal bilayers and exploitation of it for magnetization switching using an in-plane current. As the spin-orbit torque is inversely proportional to the thickness of the ferromagnetic layer, sizable effect has only been realized in bilayers with an ultrathin ferromagnetic layer. Here we demonstrate that, by stacking ultrathin Pt and FeMn alternately, both ferromagnetic properties and current induced spin-orbit torque can be achieved in FeMn/Pt multilayers without any constraint on its total thickness...
2016: Scientific Reports
Lyndon Koens, Eric Lauga
The drag anisotropy of slender filaments is a critical physical property allowing swimming in low-Reynolds number flows, and without it linear translation is impossible. Here we show that, in contrast, net rotation can occur under isotropic drag. We first demonstrate this result formally by considering the consequences of the force- and torque-free conditions on swimming bodies and we then illustrate it with two examples (a simple swimmers made of three rods and a model bacterium with two helical flagellar filaments)...
April 2016: Physical Review. E
Taoming Liu, M Cenk Çavuşoğlu
This paper presents algorithms for selection of needle grasp and for selection of entry ports of robotic instruments, for autonomous robotic execution of the minimally invasive surgical suturing task. A critical issue for automatic execution of surgical tasks, such as suturing, is the choice of needle grasp for the robotic system. Inappropriate needle grasp increases operating time requiring multiple regrasps to complete the desired task. In robotic minimally invasive surgery, the entry port that the surgical robot goes through into the patient's body has a significant role on the performance of the robot...
April 2016: IEEE Transactions on Automation Science and Engineering: a Publication of the IEEE Robotics and Automation Society
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