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Critical torque

Natalie R Janzen, Robert E Hight, Darshit S Patel, Jason A Campbell, Rebecca D Larson, Christopher D Black
Characterization of critical power/torque (CP/CT) during voluntary exercise requires maximal effort, making difficult for those with neuromuscular impairments. To address this issue we sought to determine if electrically stimulated intermittent isometric exercise resulted in a critical end-test torque (ETT) that behaved similar to voluntary CT. In the first experiment participants (n = 9) completed four bouts of stimulated exercise at a 3:2 duty cycle, at frequencies of 100, 50, 25 Hz, and a low frequency below ETT (Sub-ETT; ≤ 15 Hz)...
May 2, 2018: European Journal of Applied Physiology
Maarten M van Oene, Seungkyu Ha, Tessa Jager, Mina Lee, Francesco Pedaci, Jan Lipfert, Nynke H Dekker
Single-molecule manipulation techniques have provided unprecedented insights into the structure, function, interactions, and mechanical properties of biological macromolecules. Recently, the single-molecule toolbox has been expanded by techniques that enable measurements of rotation and torque, such as the optical torque wrench (OTW) and several different implementations of magnetic (torque) tweezers. Although systematic analyses of the position and force precision of single-molecule techniques have attracted considerable attention, their angle and torque precision have been treated in much less detail...
April 24, 2018: Biophysical Journal
Priyadarshini Thiyam, Prachi Parashar, K V Shajesh, Oleksandr I Malyi, Mathias Boström, Kimball A Milton, Iver Brevik, Clas Persson
The Casimir-Lifshitz torque between two biaxially polarizable anisotropic planar slabs is shown to exhibit a nontrivial sign reversal in its rotational sense. The critical distance a_{c} between the slabs that marks this reversal is characterized by the frequency ω_{c}∼c/2a_{c} at which the in-planar polarizabilities along the two principal axes are equal. The two materials seek to align their principal axes of polarizabilities in one direction below a_{c}, while above a_{c} their axes try to align rotated perpendicular relative to their previous minimum energy orientation...
March 30, 2018: Physical Review Letters
Wataru Koshibae, Naoto Nagaosa
An emergent topological particle in magnets, skyrmion, has several unique features distinct from the other magnetic textures such as domain wall, helical structure, and vortex. It is characterized by a topological integer called skyrmion number N sk , which counts how many times the directions of the magnetic moments wrap the unit sphere. This N sk gives the chiral nature of the skyrmion dynamics, and leads to the extremely small critical current density j c for the current-driven motion in terms of spin transfer torque effect...
April 20, 2018: Scientific Reports
Paulo Cesar do Nascimento Salvador, Kristopher Mendes de Souza, Ricardo Dantas de Lucas, Luiz Guilherme Antonacci Guglielmo, Benedito Sérgio Denadai
We hypothesized that prior exercise would attenuate the muscle fatigue accompanied by the VO2SC behavior during a subsequent very heavy (VH) intensity cycling exercise. Thirteen healthy male subjects performed tests to determine the critical power (CP) and W' and six square-wave bouts until 3 or 8 min, each at a work rate set to deplete 70 % W' in 8 min, with an maximal isokinetic effort (MIE) before and after the conditions without (VHCON) and with prior exercise (VHEXP), to measure the cycling peak torque decrement...
March 22, 2018: Applied Physiology, Nutrition, and Metabolism, Physiologie Appliquée, Nutrition et Métabolisme
Luke Kaplan, Athena Ierokomos, Praveen Chowdary, Zev Bryant, Bianxiao Cui
Long-distance axonal transport is critical to the maintenance and function of neurons. Robust transport is ensured by the coordinated activities of multiple molecular motors acting in a team. Conventional live-cell imaging techniques used in axonal transport studies detect this activity by visualizing the translational dynamics of a cargo. However, translational measurements are insensitive to torques induced by motor activities. By using gold nanorods and multichannel polarization microscopy, we simultaneously measure the rotational and translational dynamics for thousands of axonally transported endosomes...
March 2018: Science Advances
M Travis Byrd, Brian J Wallace, Jody L Clasey, Haley C Bergstrom
This study examined the contribution of lower body strength and isokinetic peak torque measures to the prediction of critical power (CP) and anaerobic work capacity (AWC). Fourteen recreationally trained males (mean ± SD age: 22.4 ± 2.5 yrs; height: 177.9 ± 7.7 cm; body mass: 84.2 ± 12.4 kg) with anaerobic training experience completed this study. The lower body strength measures included one repetition max (1RM) bilateral back squat [BSq], isokinetic peak torque at 30°·sec [PT30] and isokinetic peak torque at 240°·sec [PT240]) of the dominant leg...
February 27, 2018: Journal of Strength and Conditioning Research
Jan Gimsa
AC fields induce charges at the structural interfaces of particles or biological cells. The interaction of these charges with the field generates frequency-dependent forces that are the basis for AC-electrokinetic effects such as dielectrophoresis (DEP), electrorotation (ROT), electro-orientation, and electro-deformation. The effects can be used for the manipulation or dielectric single-particle spectroscopy. The observation of a particular effect depends on the spatial and temporal field distributions, as well as on the shape and the dielectric and viscoelastic properties of the object...
February 21, 2018: Electrophoresis
Susan M Linder, Anson B Rosenfeldt, Andrew S Bazyk, Mandy Miller Koop, Sarah Ozinga, Jay L Alberts
Background Individuals with stroke present with motor control deficits resulting in the abnormal activation and timing of agonist and antagonist muscles and inefficient movement patterns. The analysis of pedaling biomechanics provides a window into understanding motor control deficits, which vary as a function of workload. Understanding the relationship between workload and motor control is critical when considering exercise prescription during stroke rehabilitation. Objectives To characterize pedaling kinematics and motor control processes under conditions in which workload was systematically increased to an eventual patient-specific maximum...
May 2018: Topics in Stroke Rehabilitation
Mengxing Wang, Wenlong Cai, Kaihua Cao, Jiaqi Zhou, Jerzy Wrona, Shouzhong Peng, Huaiwen Yang, Jiaqi Wei, Wang Kang, Youguang Zhang, Jürgen Langer, Berthold Ocker, Albert Fert, Weisheng Zhao
Perpendicular magnetic tunnel junctions based on MgO/CoFeB structures are of particular interest for magnetic random-access memories because of their excellent thermal stability, scaling potential, and power dissipation. However, the major challenge of current-induced switching in the nanopillars with both a large tunnel magnetoresistance ratio and a low junction resistance is still to be met. Here, we report spin transfer torque switching in nano-scale perpendicular magnetic tunnel junctions with a magnetoresistance ratio up to 249% and a resistance area product as low as 7...
February 14, 2018: Nature Communications
Yohei Hamada, Manami Kitamura, Yasuhiro Yamada, Yoshinori Sanada, Takamitsu Sugihara, Saneatsu Saito, Kyaw Moe, Takehiro Hirose
A new method for evaluating the in situ rock strength beneath the seafloor is proposed and applied to the Nankai Trough accretionary prism. The depth-continuous in situ rock strength is a critical parameter for numerous studies in earth science, particularly for seismology and tectonics at plate convergence zones; yet, measurements are limited owing to a lack of drilled cores. Here, we propose a new indicator of strength, the equivalent strength (EST), which is determined only by drilling performance parameters such as drill string rotational torque, bit depth, and string rotational speed...
February 14, 2018: Scientific Reports
Jonathan D Gelber, Lonnie Soloff, Mark S Schickendantz
Overhead athletes subject their shoulders to extreme repetitive torque, compression, distraction, and translation stresses, resulting in adaptive changes of the soft tissues and osseous structures within and around the glenohumeral joint. These anatomic adaptations result in biomechanical enhancements, which improve performance. Understanding the difference between necessary and adaptive changes and pathologic findings is critical when making treatment decisions. Injuries to the shoulder of the overhead athlete can be generally classified into three groups: internal impingement, internal impingement with acquired secondary anterior instability, and primary anterior or multidirectional instability...
March 15, 2018: Journal of the American Academy of Orthopaedic Surgeons
Christopher M McAndrew, Avinesh Agarwalla, Adam C Abraham, Eric Feuchtbaum, William M Ricci, Simon Y Tang
BACKGROUND: Successful fracture fixation depends critically on the stability of the screw-bone interface. Maximum achievable screw torque reflects the competence of this interface, but it cannot be quantified prior to screw stripping. Typically, the surgeon relies on the patients' bone mineral density and radiographs, along with experience and tactile feedback to assess whether sufficient compression can be generated by the screw and bone. However, the local bone quality would also critically influence the strength of the bone-screw interface...
February 2018: Clinical Biomechanics
Takahide Kubota, Yusuke Ina, Zhenchao Wen, Koki Takanashi
Current perpendicular-to-plane (CPP) giant magnetoresistance (GMR) effects are of interest in a possible application of magnetic sensor elements, such as read-head of hard disk drives. To improve the junction performance, the interface tailoring effects were investigated for the Heulser alloy, Co₂Fe0.4 Mn0.6 Si (CFMS), based CPP-GMR junctions with an L 1 2 -Ag₃Mg ordered alloy spacer. Ultra-thin Fe or Mg inserts were utilized for the CFMS/Ag₃Mg interfaces, and CPP-GMR at low bias current density, J and the J dependence were evaluated for the junctions...
January 31, 2018: Materials
Mehdi Kordi, Campbell Menzies, Len Parker Simpson
PURPOSE: The curvature constant (W') and asymptote (critical power; CP) of the power-duration relationship are important parameters for explaining cycling performance. Short-duration endurance cycling events rely more heavily on the W'; however, the full mechanistic underpinning of this parameter is yet to be determined. Evidence suggests both muscle volume and muscle strength may contribute to the magnitude of W'. Therefore, the present study investigated the relationship between power-duration parameters (CP and W') and (1) anthropometric and (2) mechanical properties of thigh muscles in a sample of elite cyclists...
March 2018: European Journal of Applied Physiology
Paul T Morgan, Joanna L Bowtell, Anni Vanhatalo, Andrew M Jones, Stephen J Bailey
AIM: Acetaminophen is a commonly used medicine for pain relief and emerging evidence suggests that it may improve endurance exercise performance. This study investigated some of the physiological mechanisms by which acute acetaminophen ingestion might blunt muscle fatigue development. METHODS: Thirteen active males completed 60 × 3 s maximum voluntary contractions (MVC) of the knee extensors with each contraction separated by a 2 s passive recovery period...
March 2018: European Journal of Applied Physiology
Keitaro Matsukawa, Yuichiro Abe, Yoshihide Yanai, Yoshiyuki Yato
BACKGROUND: The sufficiency of screw anchoring is a critical factor for achieving successful spinal fusion; however, no reliable method for predicting pedicle screw fixation has been established. Recently, Hounsfield units (HU) obtained from computed tomography (CT) was developed as a new reliable tool to determine the bone quality. The purpose of the present study was to demonstrate the utility of regional HU measurement of the screw trajectory to predict the primary and long-term fixation strength of pedicle screws...
February 2018: Acta Neurochirurgica
W Grymonpré, G Verstraete, V Vanhoorne, J P Remon, T De Beer, C Vervaet
The concept of twin-screw melt granulation (TSMG) has steadily (re)-gained interest in pharmaceutical formulation development as an intermediate step during tablet manufacturing. However, to be considered as a viable processing option for solid oral dosage forms there is a need to understand all critical sources of variability which could affect this granulation technique. The purpose of this study was to provide an in-depth analysis of the continuous TSMG process in order to expose the critical process parameters (CPP) and elucidate the impact of process and formulation parameters on the critical quality attributes (CQA) of granules and tablets during continuous TSMG...
March 2018: European Journal of Pharmaceutics and Biopharmaceutics
J Matt McCrary, Bronwen J Ackermann, Mark Halaki
OBJECTIVES: Electromyographic (EMG) fatigue threshold (EMGFT ) is utilised as a correlate of critical power, torque, and force thresholds that establishes a theoretical exercise intensity-the power, torque, or force at which the rate of change of EMG amplitude (ΔEM¯G) is zero-below which neuromuscular fatigue is negligible and unpredictable. Recent studies demonstrating neuromuscular fatigue below critical thresholds raise questions about the construct validity of EMGFT . The purpose of this analysis is to evaluate the construct validity of EMGFT by aggregating ΔEM¯G and time to task failure (Tlim ) data...
November 11, 2017: Journal of Science and Medicine in Sport
Chang-Woo Cho, Jonathan Haiwei Yang, Noah F Q Yuan, Junying Shen, Thomas Wolf, Rolf Lortz
We investigate the magnetic phase diagram near the upper critical field of KFe_{2}As_{2} by magnetic torque and specific heat experiments using a high-resolution piezorotary positioner to precisely control the parallel alignment of the magnetic field with respect to the FeAs layers. We observe a clear double transition when the field is strictly aligned in the plane and a characteristic upturn of the upper critical field line, which goes far beyond the Pauli limit at 4.8 T. This provides firm evidence that a Fulde-Ferrell-Larkin-Ovchinnikov state exists in this iron-based KFe_{2}As_{2} superconductor...
November 24, 2017: Physical Review Letters
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