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https://www.readbyqxmd.com/read/28622581/assessment-of-atherosclerotic-luminal-narrowing-of-coronary-arteries-based-on-morphometrically-generated-visual-guides
#1
Rolf F Barth, David A Kellough, Patricia Allenby, Luke E Blower, Scott H Hammond, Greg M Allenby, L Maximilian Buja
BACKGROUND AND AIMS: Determination of the degree of stenosis of atherosclerotic coronary arteries is an important part of postmortem examination of the heart, but, unfortunately, estimation of the degree of luminal narrowing can be imprecise and tends to be approximations. Visual guides can be useful to assess this, but earlier attempts to develop such guides did not employ digital technology. Using this approach, we have developed two computer-generated morphometric guides to estimate the degree of luminal narrowing of atherosclerotic coronary arteries...
May 30, 2017: Cardiovascular Pathology: the Official Journal of the Society for Cardiovascular Pathology
https://www.readbyqxmd.com/read/28619447/similar-movements-are-associated-with-drastically-different-muscle-contraction-velocities
#2
Daniel A Hagen, Francisco J Valero-Cuevas
We investigated how kinematic redundancy interacts with the neurophysiological control mechanisms required for smooth and accurate, rapid limb movements. Biomechanically speaking, tendon excursions are over-determined because the rotation of few joints determines the lengths and velocities of many muscles. But how different are the muscle velocity profiles induced by various, equally valid hand trajectories? We used an 18-muscle sagittal-plane arm model to calculate 100,000 feasible shoulder, elbow, and wrist joint rotations that produced valid basketball free throws with different hand trajectories, but identical initial and final hand positions and velocities...
May 31, 2017: Journal of Biomechanics
https://www.readbyqxmd.com/read/28601489/is-the-subscapularis-normal-after-the-open-latarjet-procedure-an-isokinetic-and-magnetic-resonance-imaging-evaluation
#3
Alexandre Caubère, Damien Lami, Pascal Boileau, Sébastien Parratte, Matthieu Ollivier, Jean-Noël Argenson
BACKGROUND: The Latarjet procedure is considered to be a violation of the subscapularis muscle. This study evaluated the postoperative status of the subscapularis through isokinetic and magnetic resonance imaging analysis after splitting. We hypothesized that compared with a healthy contralateral shoulder, there would be satisfactory recovery of subscapularis strength at the cost of some fatigability and some mild fatty infiltration. MATERIALS AND METHODS: This was a case-control retrospective study of patients who underwent a Latarjet procedure between January 2013 and January 2015...
June 7, 2017: Journal of Shoulder and Elbow Surgery
https://www.readbyqxmd.com/read/28572997/a-superlinear-iteration-method-for-calculation-of-finite-length-journal-bearing-s-static-equilibrium-position
#4
Wenjie Zhou, Xuesong Wei, Leqin Wang, Guangkuan Wu
Solving the static equilibrium position is one of the most important parts of dynamic coefficients calculation and further coupled calculation of rotor system. The main contribution of this study is testing the superlinear iteration convergence method-twofold secant method, for the determination of the static equilibrium position of journal bearing with finite length. Essentially, the Reynolds equation for stable motion is solved by the finite difference method and the inner pressure is obtained by the successive over-relaxation iterative method reinforced by the compound Simpson quadrature formula...
May 2017: Royal Society Open Science
https://www.readbyqxmd.com/read/28569046/training-improves-vibrotactile-spatial-acuity-and-intensity-discrimination-on-the-lower-back-using-coin-motors
#5
H Christiaan Stronks, Janine Walker, Daniel J Parker, Nick Barnes
Tactile vision substitution devices are assistive technologies for the blind that redirect visual information to the tactile sense. They typically include a tactile display that conveys visual information to the skin. Two important parameters that determine the maximum information bandwidth of tactile displays are the spatial acuity of the skin, and the ability of the user to discriminate between stimulus intensities. These two parameters were investigated by determining the two-point discrimination (TPD) threshold and the just-noticeable intensity difference (JND) using coin motors on the lower back...
June 1, 2017: Artificial Organs
https://www.readbyqxmd.com/read/28560493/three-dimensional-analysis-of-linear-vestibulo-ocular-reflex-in-humans-during-eccentric-rotation-while-facing-downwards
#6
Takao Imai, Yasumitsu Takimoto, Noriaki Takeda, Tomoko Okumura, Hidenori Inohara
When participants undergo eccentric rotation (ER), i.e., they are rotated while displaced from the axis of rotation, they undergo both rotational stimulation and linear acceleration, which induces both the angular vestibulo-ocular reflex (aVOR) and linear VOR (lVOR). During ER, the lVOR induced by tangential linear acceleration enhances the eye movement induced by aVOR. In this study, we attempted to measure aVOR and lVOR separately, while participants underwent ER while facing the ground in a dark room. We analyzed three-dimensional eye movements using a video-oculography system...
May 30, 2017: Experimental Brain Research. Experimentelle Hirnforschung. Expérimentation Cérébrale
https://www.readbyqxmd.com/read/28515976/the-acute-effects-of-concentric-versus-eccentric-muscle-fatigue-on-shoulder-active-repositioning-sense
#7
Guido Spargoli
PURPOSE/BACKGROUND: Shoulder proprioception is essential in the activities of daily living as well as in sports. Acute muscle fatigue is believed to cause a deterioration of proprioception, increasing the risk of injury. The purpose of this study was to evaluate if fatigue of the shoulder external rotators during eccentric versus concentric activity affects shoulder joint proprioception as determined by active reproduction of position. STUDY DESIGN: Quasi-experimental trial...
April 2017: International Journal of Sports Physical Therapy
https://www.readbyqxmd.com/read/28453556/characterization-of-interfragmentary-motion-associated-with-common-osteosynthesis-devices-for-rat-fracture-healing-studies
#8
Nicholaus Meyers, Matthias Sukopp, Rudolf Jäger, Malte Steiner, Romano Matthys, Bernd Lapatki, Anita Ignatius, Lutz Claes
Rat models are widely used in preclinical studies investigating fracture healing. The interfragmentary movement at a fracture site is critical to the course of healing and therefore demands definition in order to aptly interpret the experimental results. Estimation of this movement requires knowledge of the fixation stiffness and loading. The characteristic loading for the rat femur has been estimated, but the stiffness of fixation used in rat studies has yet to be fully described. This study aimed to determine the 6 degree of freedom stiffness of four commonly used implants, two external fixators (RatExFix and UlmExFix), a locking plate, and a locking intramedullary nail, in all degrees of freedom and estimate the interfragmentary movement under specific physiological loads...
2017: PloS One
https://www.readbyqxmd.com/read/28452832/shoulder-dynamic-control-ratio-and-rotation-range-of-motion-in-female-junior-elite-handball-players-and-controls
#9
Robert van Cingel, Bas Habets, Linn Willemsen, Bart Staal
OBJECTIVE: To compare glenohumeral range of motion and shoulder rotator muscle strength in healthy female junior elite handball players and controls. DESIGN: Cross-sectional case-control study. SETTING: Sports medical center. PARTICIPANTS: Forty elite female handball players and 30 controls active in nonoverhead sports participated in this study. MAIN OUTCOME MEASURES: Passive external rotator (ER), internal rotator (IR), and total range of motion (TROM) of the dominant and nondominant arm were examined with a goniometer...
April 27, 2017: Clinical Journal of Sport Medicine: Official Journal of the Canadian Academy of Sport Medicine
https://www.readbyqxmd.com/read/28414265/effectiveness-of-a-home-based-eccentric-exercise-program-on-the-torque-angle-relationship-of-the-shoulder-external-rotators-a-pilot-study
#10
Timothy L Uhl, Thomas Rice, Brianna Papotto, Timothy A Butterfield
CONTEXT: The role of the rotator cuff is to provide dynamic stability to the glenohumeral joint. Human and animal studies have identified sarcomerogenesis as an outcome of eccentric training indicated by more torque generation with the muscle in a lengthened position. OBJECTIVE: The authors hypothesized that a home-based eccentric-exercise program could increase the shoulder external rotators' eccentric strength at terminal internal rotation (IR). DESIGN: Prospective case series...
April 2017: Journal of Sport Rehabilitation
https://www.readbyqxmd.com/read/28315596/effects-of-hip-and-trunk-muscle-strengthening-on-hip-function-and-lower-limb-kinematics-during-step-down-task
#11
Vanessa Lara Araújo, Thales Rezende Souza, Viviane Otoni do Carmo Carvalhais, Aline Castro Cruz, Sérgio Teixeira Fonseca
BACKGROUND: Strengthening of the hip and trunk muscles has the potential to change lower limb kinematic patterns, such as excessive hip medial rotation and adduction during weight-bearing tasks. This study aimed to investigate the effect of hip and trunk muscles strengthening on hip muscle performance, hip passive properties, and lower limb kinematics during step-down task in women. METHODS: Thirty-four young women who demonstrated dynamic knee valgus during step-down were divided into two groups...
May 2017: Clinical Biomechanics
https://www.readbyqxmd.com/read/28293194/quantification-of-internal-stress-strain-fields-in-human-tendon-unraveling-the-mechanisms-that-underlie-regional-tendon-adaptations-and-mal-adaptations-to-mechanical-loading-and-the-effectiveness-of-therapeutic-eccentric-exercise
#12
REVIEW
Constantinos N Maganaris, Panagiotis Chatzistergos, Neil D Reeves, Marco V Narici
By virtue of their anatomical location between muscles and bones, tendons make it possible to transform contractile force to joint rotation and locomotion. However, tendons do not behave as rigid links, but exhibit viscoelastic tensile properties, thereby affecting the length and contractile force in the in-series muscle, but also storing and releasing elastic stain energy as some tendons are stretched and recoiled in a cyclic manner during locomotion. In the late 90s, advancements were made in the application of ultrasound scanning that allowed quantifying the tensile deformability and mechanical properties of human tendons in vivo...
2017: Frontiers in Physiology
https://www.readbyqxmd.com/read/28281302/compensation-of-corneal-oblique-astigmatism-by-internal-optics-a-theoretical-analysis
#13
Tao Liu, Larry N Thibos
PURPOSE: Oblique astigmatism is a prominent optical aberration of peripheral vision caused by oblique incidence of rays striking the refracting surfaces of the cornea and crystalline lens. We inquired whether oblique astigmatism from these two sources should be expected, theoretically, to have the same or opposite signs across the visual field at various states of accommodation. METHODS: Oblique astigmatism was computed across the central visual field for a rotationally-symmetric schematic-eye using optical design software...
May 2017: Ophthalmic & Physiological Optics: the Journal of the British College of Ophthalmic Opticians (Optometrists)
https://www.readbyqxmd.com/read/28261432/comparison-of-clinical-and-radiological-results-according-to-glenosphere-position-in-reverse-total-shoulder-arthroplasty-a-short-term-follow-up-study
#14
Chang Hyuk Choi, Sung Guk Kim, Jae Jun Lee, Byung Hoon Kwack
BACKGROUND: In a previous biomechanical study, eccentric glenospheres with more inferior position of the center of rotation were shown to improve range of motion and reduce the incidence of scapular notching after reverse total shoulder arthroplasty (RSA). The purpose of this study was to compare the clinical and radiological results of RSA using an eccentric glenosphere to those using a concentric glenosphere and to determine the usefulness of the eccentric glenosphere. METHODS: From 2009 to 2015, we performed a retrospective review of 20 consecutive patients who underwent RSA using a deltopectoral approach...
March 2017: Clinics in Orthopedic Surgery
https://www.readbyqxmd.com/read/28185809/hip-strength-and-range-of-motion-normal-values-from-a-professional-football-league
#15
Andrea B Mosler, Kay M Crossley, Kristian Thorborg, Rod J Whiteley, Adam Weir, Andreas Serner, Per Hölmich
OBJECTIVES: To determine the normal profiles for hip strength and range of motion (ROM) in a professional football league in Qatar, and examine the effect of leg dominance, age, past history of injury, and ethnicity on these profiles. DESIGN: Cross-sectional cohort study. METHODS: Participants included 394 asymptomatic, male professional football players, aged 18-40 years. Strength was measured using a hand held dynamometer with an eccentric test in side-lying for hip adduction and abduction, and the squeeze test in supine with 45° hip flexion...
April 2017: Journal of Science and Medicine in Sport
https://www.readbyqxmd.com/read/28159312/effects-of-anterior-offsetting-of-humeral-head-component-in-posteriorly-unstable-total-shoulder-arthroplasty-finite-element-modeling-of-cadaver-specimens
#16
Gregory S Lewis, William K Conaway, Hwabok Wee, H Mike Kim
A novel technique of "anterior offsetting" of the humeral head component to address posterior instability in total shoulder arthroplasty has been proposed, and its biomechanical benefits have been previously demonstrated experimentally. The present study sought to characterize the changes in joint mechanics associated with anterior offsetting with various amounts of glenoid retroversion using cadaver specimen-specific 3-dimensional finite element models. Specimen-specific computational finite element models were developed through importing digitized locations of six musculotendinous units of the rotator cuff and deltoid muscles based off three cadaveric shoulder specimens implanted with total shoulder arthroplasty in either anatomic or anterior humeral head offset...
February 28, 2017: Journal of Biomechanics
https://www.readbyqxmd.com/read/28140781/standard-and-short-rom-isokinetic-testing-comparative-analysis-in-identifying-submaximal-shoulder-external-rotator-effort
#17
Eduard Pujol, Joaquim Chaler, Laura Sucarrats, Inés López, Blanca Zeballos, Roser Garreta, Zeevi Dvir
An isokinetic-related parameter termed the difference between eccentric-concentric strength ratios at two distinct test velocities (DEC) based on 60° (standard) range of motion (RoM) has been proven to be highly efficient detecting feigned muscular efforts. This study aimed to verify whether a DEC derived from a much shorter test RoM (20°) was equally useful than a long RoM-derived one. Eighteen healthy men (32.4 ± 6.4 years old) took part in a study focusing on shoulder external rotation isokinetic strength...
January 31, 2017: Journal of Motor Behavior
https://www.readbyqxmd.com/read/28047829/th-ab-201-07-filmless-treatment-localization-qa-for-the-cyberknife-system
#18
J Gersh, M Noll
PURPOSE: Accuray recommends daily evaluation of the treatment localization and delivery systems (TLS/TDS) of the CyberKnife. The vendor-provided solution is a Winston-Lutz-type test that evaluates film shadows from an orthogonal beam pair (known as AQA). Since film-based techniques are inherently inefficient and potentially inconsistent and uncertain, this study explores a method which provides a comparable test with greater efficiency, consistency, and certainty. This test uses the QAStereoChecker (QASC, Standard Imaging, Inc...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28047456/mo-de-207a-06-ecg-gated-ct-reconstruction-for-a-c-arm-inverse-geometry-x-ray-system
#19
J M Slagowski, Dap Dunkerley
PURPOSE: To obtain ECG-gated CT images from truncated projection data acquired with a C-arm based inverse geometry fluoroscopy system, for the purpose of cardiac chamber mapping in interventional procedures. METHODS: Scanning-beam digital x-ray (SBDX) is an inverse geometry fluoroscopy system with a scanned multisource x-ray tube and a photon-counting detector mounted to a C-arm. In the proposed method, SBDX short-scan rotational acquisition is performed followed by inverse geometry CT (IGCT) reconstruction and segmentation of contrast-enhanced objects...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/27967273/eccentric-overload-training-in-team-sports-functional-performance-constant-bilateral-vertical-vs-variable-unilateral-multidirectional-movements
#20
Oliver Gonzalo-Skok, Julio Tous-Fajardo, Carlos Valero-Campo, César Berzosa, Ana Vanessa Bataller, José Luis Arjol-Serrano, Gerard Moras, Alberto Mendez-Villanueva
PURPOSE: This study analyzed the effects of two different eccentric overload training (EOT) programs, using a rotational conical-pulley, on functional performance in team-sports players. A traditional movement paradigm (i.e., squat) including several sets of one bilateral and vertical movement was compared to a novel paradigm including a different exercise in each set of unilateral and multidirectional movements. METHODS: Forty-eight amateur/semiprofessional team-sport players were randomly assigned to an EOT program including either the same bilateral-vertical (CBV, n=24) movement (squat) or different unilateral-multidirectional (VUMD, n=24) movements...
December 14, 2016: International Journal of Sports Physiology and Performance
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