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https://www.readbyqxmd.com/read/28208410/local-equilibria-and-state-transfer-of-charged-classical-particles-on-a-helix-in-an-electric-field
#1
J Plettenberg, J Stockhofe, A V Zampetaki, P Schmelcher
We explore the effects of a homogeneous external electric field on the static properties and dynamical behavior of two charged particles confined to a helix. In contrast to the field-free setup which provides a separation of the center-of-mass and relative motion, the existence of an external force perpendicular to the helix axis couples the center-of-mass to the relative degree of freedom leading to equilibria with a localized center of mass. By tuning the external field various fixed points are created and/or annihilated through different bifurcation scenarios...
January 2017: Physical Review. E
https://www.readbyqxmd.com/read/28174454/effect-of-short-term-fatigue-induced-by-high-intensity-exercise-on-the-profile-of-the-ground-reaction-force-during-single-leg-anterior-drop-jumps
#2
Saya Watanabe, Junya Aizawa, Manabu Shimoda, Mitsuhiro Enomoto, Tomomasa Nakamura, Atushi Okawa, Kazuyoshi Yagishita
[Purpose] Fatigue may be an important contributing factor to non-contact anterior cruciate ligament injuries in sports. The purpose of this study was to evaluate the effects of controlled lower limb fatigue, induced by a short-term, high-intensity exercise protocol, on the profile of the ground reaction force during landings from single-leg anterior drop-jumps. [Subjects and Methods] Twelve healthy males, 18 to 24 years old, performed single-leg anterior drop-jumps, from a 20 cm height, under two conditions, 'fatigue' and 'non-fatigue'...
December 2016: Journal of Physical Therapy Science
https://www.readbyqxmd.com/read/28157574/anatomical-masking-of-pressure-footprints-based-on-the-oxford-foot-model-validation-and-clinical-relevance
#3
Claudia Giacomozzi, Julie A Stebbins
Plantar pressure analysis is widely used in the assessment of foot function. In order to assess regional loading, a mask is applied to the footprint to sub-divide it into regions of interest (ROIs). The most common masking method is based on geometric features of the footprint (GM). Footprint masking based on anatomical landmarks of the foot has been implemented more recently, and involves the integration of a 3D motion capture system, plantar pressure measurement device, and a multi-segment foot model. However, thorough validation of anatomical masking (AM) using pathological footprints has not yet been presented...
December 23, 2016: Gait & Posture
https://www.readbyqxmd.com/read/28121458/effects-of-practice-variability-on-spinal-manipulation-learning
#4
Andrée-Anne Marchand, Laura Mendoza, Claude Dugas, Martin Descarreaux, Isabelle Pagé
OBJECTIVE: To evaluate the effects of practice variability on chiropractic students' capacity to deliver spinal manipulations (SMs) of a targeted peak force. METHODS: Forty students participated in an experimental session including either a variable or a constant practice protocol of 45 SMs. SMs were delivered on a computer-connected device that recorded force-time profiles. Ten SMs with a target peak force of 350-N were performed before practice, immediately following practice, and 2 days later...
January 25, 2017: Journal of Chiropractic Education
https://www.readbyqxmd.com/read/28043054/dynamic-plantar-pressure-distribution-strength-capacity-and-postural-control-after-lisfranc-fracture-dislocation
#5
Alexander T Mehlhorn, Markus Walther, Tayfun Yilmaz, Lennart Gunst, Anja Hirschmüller, Norbert P Südkamp, Hagen Schmal
Substantial progress has been made in the operative treatment of Lisfranc fractures, however, the prognosis remains poor. We hypothesized that Lisfranc injuries change the postural control and muscle strength of the lower limb. Both are suggested to correlate with the clinical outcome and quality of life. 17 consecutive patients suffering from a Lisfranc fracture dislocation were registered, underwent open reduction and internal fixation and were followed-up for 50.5±25.7months (Mean±SDM). Biomechanical analysis of muscle strength capacities, postural control and plantar pressure distribution was assessed >6 month postoperatively...
December 19, 2016: Gait & Posture
https://www.readbyqxmd.com/read/28002178/effect-of-different-onset-thresholds-on-isometric-mid-thigh-pull-force-time-variables
#6
Thomas Dos'Santos, Paul A Jones, Paul Comfort, Christopher Thomas
Various thresholds have been used to identify the onset of contraction during isometric mid-thigh pull (IMTP) however, no agreed onset threshold exists for this assessment. The purpose of this study was to compare relative body weight (BW) and arbitrary onset thresholds to a criterion onset threshold 5 SD of BW for IMTP force-time variables; force at each threshold, peak force (PF), time-specific force values (100, 150 and 200 ms) and rate of force development (RFD) during 0-100 ms, 0-150 ms, 0-200 ms. Academy rugby league players (n = 9, age: 18...
December 8, 2016: Journal of Strength and Conditioning Research
https://www.readbyqxmd.com/read/27991615/impact-of-foot-progression-angle-modification-on-plantar-loading-in-individuals-with-diabetes-mellitus-and-peripheral-neuropathy
#7
Ericka N Merriwether, Mary K Hastings, Kathryn L Bohnert, John H Hollman, Michael J Strube, David R Sinacore
AIMS: To determine if participants can reduce foot progression angle (FPA), and if FPA reduction decreases regional plantar stresses and forces in individuals with diabetes. METHODS: Design: Three-group cross-sectional design with repeated measures. subjects: twenty-eight participants either with diabetes mellitus (DM), diabetes and peripheral neuropathy with (DMPN+NPU) or without a prior history of ulceration (DMPN-NPU) were studied. Intervention: Participants were first instructed to walk over a 3...
January 2016: Edorium J Disabil Rehabil
https://www.readbyqxmd.com/read/27924387/visual-perceptual-mismatch-in-robotic-surgery
#8
Ahmad Abiri, Anna Tao, Meg LaRocca, Xingmin Guan, Syed J Askari, James W Bisley, Erik P Dutson, Warren S Grundfest
BACKGROUND: The principal objective of the experiment was to analyze the effects of the clutch operation of robotic surgical systems on the performance of the operator. The relative coordinate system introduced by the clutch operation can introduce a visual-perceptual mismatch which can potentially have negative impact on a surgeon's performance. We also assess the impact of the introduction of additional tactile sensory information on reducing the impact of visual-perceptual mismatch on the performance of the operator...
December 6, 2016: Surgical Endoscopy
https://www.readbyqxmd.com/read/27909471/contact-force-and-atrial-fibrillation-ablation
#9
REVIEW
Ullah W, Schilling Rj, Wong T
Catheters able to measure the force and vector of contact between the catheter tip and myocardium are now available. Pre-clinical work has established that the degree of contact between the radiofrequency ablation catheter and myocardium correlates with the size of the delivered lesion. Excess contact is associated with steam pops and perforation. Catheter contact varies within the left atrium secondary to factors including respiration, location, atrial rhythm and the trans-septal catheter delivery technology used...
February 2016: Journal of Atrial Fibrillation
https://www.readbyqxmd.com/read/27875498/a-murine-model-of-robotic-training-to-evaluate-skeletal-muscle-recovery-after-injury
#10
Stefano Lai, Alessandro Panarese, Ross Lawrence, Michael L Boninger, Silvestro Micera, Fabrisia Ambrosio
PURPOSE: In vivo studies have suggested that motor exercise can improve muscle regeneration after injury. Nevertheless, pre-clinical investigations still lack reliable tools to monitor motor performance over time and to deliver optimal training protocols to maximize force recovery. Here, we evaluated the utility of a murine robotic platform to (i) detect early impairment and longitudinal recovery after acute skeletal muscle injury and (ii) administer varying intensity training protocols to enhance forelimb motor performance...
November 21, 2016: Medicine and Science in Sports and Exercise
https://www.readbyqxmd.com/read/27871100/biomechanical-response-of-military-booted-and-unbooted-foot-ankle-tibia-from-vertical-loading
#11
Frank A Pintar, Michael B Schlick, Narayan Yoganandan, Liming Voo, Andrew C Merkle, Michael Kleinberger
A new anthropomorphic test device (ATD) is being developed by the US Army to be responsive to vertical loading during a vehicle underbody blast event. To obtain design parameters for the new ATD, a series of non-injurious tests were conducted to derive biofidelity response corridors for the foot-ankle complex under vertical loading. Isolated post mortem human surrogate (PMHS) lower leg specimens were tested with and without military boot and in different initial foot-ankle positions. Instrumentation included a six-axis load cell at the proximal end, three-axis accelerometers at proximal and distal tibia, and calcaneus, and strain gages...
November 2016: Stapp Car Crash Journal
https://www.readbyqxmd.com/read/27821946/relation-between-muscle-fiber-conduction-velocity-and-exerted-dynamic-characteristics-of-muscular-tension-in-patients-with-hemiplegia-caused-by-stroke
#12
Kenichi Murakami, Hiroyuki Fujisawa, Makoto Suzuki, Yoichiro Sato, Kentaro Sakurai, Chie Abe
[Purpose] The aim of this study was to clarify the relationships among muscle fiber conduction velocity, time-force characteristics of muscle force production, and voluntary movement in patients with hemiplegia. [Subjects and Methods] The participants in the present study were 13 patients with hemiplegia. Muscle fiber conduction velocity, deep temperature of muscles and muscle thickness were measured for the tibialis anterior, and a time force curve was obtained from dorsiflexion of the ankle and lower thigh girth (maximum, minimum) for both sides...
October 2016: Journal of Physical Therapy Science
https://www.readbyqxmd.com/read/27811299/a-general-relationship-links-gait-mechanics-and-running-ground-reaction-forces
#13
Kenneth P Clark, Laurence J Ryan, Peter G Weyand
The relationship between gait mechanics and running ground reaction forces is widely regarded as complex. This viewpoint has evolved primarily via efforts to explain the rising edge of vertical force-time waveforms observed during slow human running. Existing theoretical models do provide good rising-edge fits, but require more than a dozen input variables to sum the force contributions of four or more vague components of the body's total mass (mb). Here, we hypothesized that the force contributions of two discrete body mass components are sufficient to account for vertical ground reaction force-time waveform patterns in full (stance foot and shank, m1=0...
January 15, 2017: Journal of Experimental Biology
https://www.readbyqxmd.com/read/27749730/a-comparison-of-catch-phase-force-time-characteristics-during-clean-derivatives-from-the-knee
#14
Paul Comfort, Robert Williams, Timothy J Suchomel, Jason P Lake
The aim of this study was to compare load-absorption force-time characteristics of the clean from the knee (CK), power clean from the knee (PCK) and clean pull from the knee (CPK). Ten collegiate athletes (age 27.5 ± 4.2 years; height 180.4 ± 6.7 cm; mass 84.4 ± 7.8 kg), performed three repetitions each of the CK, PCK and CPK with 90% of their 1RM power clean on a force platform. The CK load-absorption duration (0.95 ± 0.35 s) was significantly longer compared to the CPK (0.44 ± 0.15 s; p < 0.001, d = 2...
September 27, 2016: Journal of Strength and Conditioning Research
https://www.readbyqxmd.com/read/27688433/contraction-mode-itself-does-not-determine-the-level-of-mtorc1-activity-in-rat-skeletal-muscle
#15
Satoru Ato, Yuhei Makanae, Kohei Kido, Satoshi Fujita
Resistance training with eccentric contraction has been shown to augment muscle hypertrophy more than other contraction modes do (i.e., concentric and isometric contraction). However, the molecular mechanisms involved remain unclear. The purpose of this study was to investigate the effect of muscle contraction mode on mammalian target of rapamycin complex 1 (mTORC1) signaling using a standardized force-time integral (load (weight) × contraction time). Male Sprague-Dawley rats were randomly assigned to three groups: eccentric contraction, concentric contraction, and isometric contraction...
October 2016: Physiological Reports
https://www.readbyqxmd.com/read/27669195/load-absorption-force-time-characteristics-following-the-second-pull-of-weightlifting-derivatives
#16
Timothy J Suchomel, Jason P Lake, Paul Comfort
The purpose of this study was to compare the load absorption force-time characteristics of weightlifting catching and pulling derivatives. Twelve resistance-trained men performed repetitions of the hang power clean (HPC), jump shrug (JS), and hang high pull (HHP) on a force platform with 30, 45, 65, and 80% of their one repetition maximum (1RM) HPC. Load absorption phase duration, mean force, and work were calculated from the force-time data. The HHP produced a significantly longer load absorption phase duration compared to the HPC (p < 0...
September 21, 2016: Journal of Strength and Conditioning Research
https://www.readbyqxmd.com/read/27669194/vertical-and-horizontal-impact-force-comparison-during-jump-landings-with-and-without-rotation-in-ncaa-division-1-male-soccer-players
#17
John R Harry, Leland A Barker, John A Mercer, Janet S Dufek
There is a wealth of research on impact force characteristics when landing from a jump. However, there are no data on impact forces during landing from a jump with an airborne rotation about the vertical axis. We examined impact force parameters in the vertical and horizontal axes during vertical jump (VJ) landings and vertical jump landings with a 180-degree rotation (VJR). Twenty-four Division 1 male soccer players performed three VJ and VJR landings on a dual-force platform system. Paired-samples t-tests (α=0...
September 22, 2016: Journal of Strength and Conditioning Research
https://www.readbyqxmd.com/read/27658963/selected-plantar-pressure-characteristics-associated-with-the-skating-performance-of-national-in-line-speed-skaters
#18
Wen-Lan Wu, Hsiu-Tao Hsu, I-Hua Chu, Feng-Hua Tsai, Jing-Min Liang
In order to help coaches analyse the techniques of professional in-line speed skaters for making the required fine adjustments and corrections in their push-off work, this study analysed the specific plantar pressure characteristics during a 300-m time-trial test. Fourteen elite in-line speed skaters from the national team were recruited in this study. The total completion time of the 300-m time-trial test, duration of each skating phase, and plantar pressure distribution were measured. The correlation between plantar pressure distribution and skating performance was assessed using Pearson correlation analyses...
September 23, 2016: Sports Biomechanics
https://www.readbyqxmd.com/read/27630422/correlations-between-sagittal-plane-kinematics-and-landing-impact-force-during-single-leg-lateral-jump-landings
#19
Junya Aizawa, Shunsuke Ohji, Hideyuki Koga, Tadashi Masuda, Kazuyoshi Yagishita
[Purpose] The correlations of peak vertical ground reaction force and sagittal angles during single-leg lateral jump-landing with noncontact anterior cruciate ligament injury remain unknown. This study aimed to clarify the correlations between kinematics and impact force during lateral jump-landing. [Subjects and Methods] Twenty active males were included in the analysis. A sagittal-view movie camera and force plate were time synchronized. Trunk and lower extremity sagittal angles were measured 100 ms before initial contact and at peak vertical ground reaction force...
August 2016: Journal of Physical Therapy Science
https://www.readbyqxmd.com/read/27627026/a-novel-approach-for-extracting-viscoelastic-parameters-of-living-cells-through-combination-of-inverse-finite-element-simulation-and-atomic-force-microscopy
#20
Fanan Wei, Haitao Yang, Lianqing Liu, Guangyong Li
Dynamic mechanical behaviour of living cells has been described by viscoelasticity. However, quantitation of the viscoelastic parameters for living cells is far from sophisticated. In this paper, combining inverse finite element (FE) simulation with Atomic Force Microscope characterization, we attempt to develop a new method to evaluate and acquire trustworthy viscoelastic index of living cells. First, influence of the experiment parameters on stress relaxation process is assessed using FE simulation. As suggested by the simulations, cell height has negligible impact on shape of the force-time curve, i...
September 14, 2016: Computer Methods in Biomechanics and Biomedical Engineering
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