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Results 451 - 500 of 778
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Lysack J T - - 2000
An apparatus is described that enables the application of continuous pure moment loads to multi-segment spine specimens. This loading apparatus allows continuous cycling of the spine between specified flexion and extension (or right and left lateral bending) maximum load endpoints. Using a six-degree-of-freedom load cell and three-dimensional optoelectronic stereophotogrammetry, characteristic ...
Debski R E - - 2000
The development of effective treatment and reconstruction procedures for injuries to the soft tissues around the acromioclavicular (AC) joint relies on a comprehensive understanding of overall joint function. The objective of this study was to determine the magnitude and direction of the in situ forces in the AC capsular and ...
Prajapati R T - - 2000
Regulation of mechanical force on and by connective tissues is increasingly regarded as a critical factor in understanding their function. The aim of this study was to identify quantifiable characteristics of external loading to which fibroblasts were sensitive. Specific patterns of uniaxial tensile loading were applied to fibroblast populated collagen ...
Azangwe G - - 2000
Anterior cruciate ligament (ACL) rupture is a major clinical problem leading to instability and degeneration of the knee joint. The problem is compounded by the limited ability of the ACL to heal when ruptured. The existing knowledge regarding the way the ACL ruptures is limited, and this investigation is an ...
LeRoux M A - - 2000
The mechanical properties and microstructure of articular cartilage from the canine tibial plateau were studied 12 weeks after total medial meniscectomy. The organization of the birefringent collagen network was measured with quantitative polarized light microscopy to determine the thickness and the degree of organization of the superficial and deep zones. ...
Chow J W - - 2000
The purpose of this study was to examine how resistance load influenced the kinematic characteristics and the activity of selected muscles (flexor and extensor carpi radialis, biceps brachii, triceps brachii, antero-middle and postero-middle deltoids, pectoralis major, and upper trapezius) during maximum effort racing wheelchair stroking using 3D videographic and surface ...
Chadwick E K - - 2000
Meaningful testing of stab resistant body armour requires the use of realistic body tissue simulants. A device for the determination of the force-displacement behaviour of materials in high impact loading situations has been developed for the testing of such simulants. Force measurement is achieved with the use of electrical foil ...
Nightingale R W - - 2000
Cervical spine injuries continue to be a costly societal problem. Future advancements in injury prevention depend on improved physical and computational models which, in turn, are predicated on a better understanding of the responses of the neck during dynamic loading. Previous studies have shown that the tolerance of the neck ...
Wang J L - - 2000
STUDY DESIGN: A study using a validated viscoelastic finite-element model of a L2-L3 motion segment to identify the load sharing among the passive elements at different loading rates. OBJECTIVE: To enhance understanding concerning the role of the loading rate (i.e., speed of lifting and lowering during manual material handling tasks) ...
Smith S L - - 2000
Two wear tests were conducted using the Durham Hip Joint Wear Simulator to investigate the effects of simplified motion and loading on ultra-high molecular weight polyethylene (UHMWPE) acetabular cup wear rates. Bovine serum was used as a lubricant and a gravimetric technique was used to measure wear. The first wear ...
Urban J P - - 2000
The focus of work on mechanotransduction in cartilage has changed markedly over the last 10 years. At the beginning of the decade, the interest lay in determining the net response of cartilage plugs, almost always as 35S-sulphate or 3H-proline incorporation, to a variety of external loads, with the focus on ...
Kawakami M - - 1999
The aim of this paper is to explore and present a proposal for a new work system for the aged worker. The method of research used to establish the system was to observe, record, and measure the actions of sitting workers performing assembly operations on electrical products. An evaluation index ...
Vernazza-Martin S S Laboratory of Neurobiology and Movements, CNRS, 31, chemin Joseph Aiguier, F-13402 Marseille Cedex 20, - - 1999
The aim of the present investigation was to study the adaptation of the kinematic synergy responsible for equilibrium control during upper trunk movements to a 10-kg load added to the subject's shoulders. Five adult subjects were asked to bend their upper trunk forward to an angle of 35 degrees and ...
Lung C Y - - 1999
The relative motion of 3 different bipolar endoprostheses was evaluated in vitro. A paired fresh acetabulum was frozen at 0 degrees C and defrosted 12 hours before the experiment. Three bipolar endoprostheses were evaluated: UNIQHIP system (United Orthopedics), UHR system (Osteonics), and AML system (Depuy). The surface roughness and spherical ...
Johnson C H - - 1999
The closed kinetic chain effects of peroneus longus (PL) activity on the medial column of the foot were investigated in seven fresh-frozen cadaver specimens using a three-dimensional radiowave tracking system. Specimens, consisting of the distal half of the leg and the intact ankle and foot, were mounted on a nonmetallic ...
Fetscher A E - - 1999
The bilobed stigma of many species in the order Scrophulariales closes in response to touch by an animal pollinator. In hummingbird-pollinated bush monkey flower, Mimulus aurantiacus (Scrophulariaceae), closure is rapid, occurring within seconds of tactile stimulus. We investigated the proximate causes of stigma closure and subsequent reopening in M. aurantiacus, ...
Magnissalis E A - - 1999
Observations in the field of lower limb prosthetic rehabilitation have shown that several transfemoral prostheses show signs of wear on some components of the knee unit. This is thought to be a result of severe loading developed during activities associated with kneeling. Some prostheses may have failed due to repetitive ...
Debski R E - - 1999
The passive properties of the rotator cuff have been shown to provide some stability during anterior-posterior (AP) translation. However, the relative importance of the rotator cuff to joint stability remains unclear. The purpose of this study was to quantify the force contributions of the rotator cuff and of capsuloligamentous structures ...
Debski R E - - 1999
The purpose of this study was to use an analytical approach to determine the forces in the glenohumeral ligaments during joint motion. Predictions from the analytical approach were validated by comparing them to experimental data. Using a geometric model, the lengths of the four glenohumeral ligaments were determined during anterior-posterior ...
Reilly G C - - 1999
During locomotion, the anterior cortex of the equine radius is loaded predominantly in tension, the posterior predominantly in compression. The anterior cortex is relatively strong in tension, the posterior in compression. We investigated the pattern of failure of specimens from the two cortices using laser scanning confocal microscopy. All specimens ...
Ridgel A L - - 1999
The ability to detect changes in load is important for effective use of a leg in posture and locomotion. While a number of limb receptors have been shown to encode increases in load, few afferents have been demonstrated to signal leg unloading, which occurs cyclically during walking and is indicative ...
Ling W - - 1999
OBJECTIVES: To compare the effects of the soft cushion setting with those of the hard cushion setting of a Biodex II isokinetic dynamometer on peak velocity and peak torque with six loads at 23 preset speeds. DESIGN: Mixed within- and between-groups, repeated-measures design. SETTING: Research laboratory of a physical therapy ...
Carpentier A - - 1999
This study analyses the relative contribution of the triceps surae and tibialis anterior (TA) muscles to tension development with reference to voluntary plantarflexion at two articular positions of the knee joint (extended and flexed at 90 degrees) for various inertial loads. Subjects were instructed to perform plantarflexions at various sub-maximal ...
Löw A - - 1999
Event-related potentials were recorded during a delayed matching-to-sample design from 17 volunteers (5 f) using high-resolution (65 channels) EEG-recordings. In the two-stimulus paradigm, the 500-ms stimulus S1 comprised a visual pattern of two diamonds differing in size, angular rotation and location; in the delay period, Working Memory (WM) load was ...
Cordey J - - 1999
A loading model permitting the application of relevant loads to the diaphysis and constructed on the basis of current knowledge of the biomechanics of the femur will be presented. This model takes into account the force acting through the ilio-tibial tract in the frontal plane and the forces acting on ...
Powers W J - - 1999
Odors are generated primarily as the result of manure storage but also result from animal housing and manure application. Effective odor control is dependent upon implementation of strategies that are complementary to management practices. Some systems use a deep pit or a holding tank for manure storage. In such systems, ...
Charteris J - - 1998
Load-bearing over variable distances at diverse speeds constitutes a major component of manual materials handling activities that persist as ergonomic concerns even in the most technologically advanced societies. The mechanisms of slipping and tripping relate in part to the way pedal segments approach or leave the walking surface. To demonstrate ...
Belda P M - - 1998
The quality of force measurement in an eccentric tabletting machine equipped with piezo-electric load washers mounted under pre-stress at the upper and lower punches, and the reliability of their calibration in situ and under working conditions were carefully investigated, since this tabletting machine is used as an 'analytical instrument' for ...
Milner T E TE Institut de réadaptation de Montréal, Canada. - - 1998
Damping characteristics of the musculoskeletal system were investigated during rapid voluntary wrist flexion movements. Oscillations about the final position were induced by introducing a load with the characteristics of negative damping, which artificially reduced the damping of the wrist. Subjects responded to increases in the negatively damped load by stronger ...
Ji J - - 1998
OBJECTIVE: An event-related potential (ERP) correlate of visual short-term memory (VMP) has been identified in our laboratory. This study aims to determine how stimulus load modulates recognition processing of digits. METHODS: ERPs were recorded from 117 healthy right-handed subjects during a delayed matching-to-sample paradigm, using number stimuli that were either ...
Wierzbicka M M - - 1998
The purpose of this study was to investigate whether the central nervous system (CNS) motor program subserving most-rapid voluntary force pulse generation is modified according to the level of agonist muscle load maintained prior to the pulse. Five normal subjects produced most-rapid force pulses to a target of 20% maximum ...
Sharkey Neil A. - - 1998
OBJECTIVE: This study was undertaken to evaluate the performance of a new dynamic laboratory model of the stance phase of gait. DESIGN: Five cadaver feet were repetitively tested in the apparatus. BACKGROUND: Typical biomechanical investigations of cadaver feet simply place a static load on the tibia. The present system was ...
Hooper David M. - - 1998
OBJECTIVE: To better understand the loads placed on the spine during asymmetric lifting. DESIGN: Analysis of variance was used to test the effects of asymmetry (0, 45, 90 degrees ), event (up, down, min and max), and trial (first and second) on applied spine moments and resulting EMG signals in ...
Arbogast K B - - 1998
Traumatic damage to the brainstem occurs frequently when the brain skull complex experiences injurious loading especially during those traumatic situations that produce diffuse axonal injury (DAI). DAI has been shown to be dependent on load direction and correlated with regional tissue deformation in response to rotational inertial loads. Possible mechanisms ...
Serrien D J DJ Department of Kinesiology, K.U. Leuven, Heverlee, - - 1998
Two-limb coordination of homologous and non-homologous effectors was examined during isofrequency (1:1) and multifrequency (2:1) conditions. The coordination patterns involved flexion and extension movements in the sagittal plane and were performed under unloaded and single-limb (right arm) loaded conditions. Previous studies suggested that the lower degree of 1:1 synchronization observed ...
Broom N D - - 1998
The physicochemically derived swelling stress in articular cartilage plays a crucial role in determining the pattern of stress sharing between the exudable fluid and the 'solid' components comprising its matrix. This pattern of stress sharing in turn influences the manner in which cartilage consolidates or deforms in compression via the ...
Lindahl O A - - 1998
A spring loaded tactile sensor with displacement sensing has been evaluated for non-invasive assessment of physical properties, stiffness and elasticity, of human skin in vivo. The tactile sensor consists of a peizoelectric vibrator (61 kHz) with a vibration pickup, electronics and PC with software for measurement of the change in ...
Abu-Hassan M I - - 1998
Disc-shaped specimens are frequently tested in order to establish an understanding of the properties of ceramic material. In this study three-dimensional finite element stress analysis has been used to investigate the loading characteristics of this shape of specimen and the effect of incorporating scratches and voids into its structure. The ...
Markolf K L - - 1998
Custom-designed miniature load-cells were inserted into the distal end of the ulna and the proximal end of the radius in ten fresh-frozen forearms from cadavera. The forces transmitted through the bones at these sites were measured under 134 newtons of constant axial load that was applied through the metacarpals as ...
Inoue H - - 1998
To evaluate the mechanical effect of the direction of facet load on the isthmus stresses of the lower lumbar neural arch, stress analyses were performed by using three-dimensional finite element models of isolated L4 and L5 vertebrae with particular emphasis on accurate discretization of the posterior elements. The bilateral symmetric ...
Hardy M - - 1998
The anatomic architecture of connective tissue is dependent on the stresses associated with motion. Immobilization results in stress deprivation, causing structural changes in the tissue matrix. The structural changes that occur are due to the remodeling of tissue to its new resting length while being held immobile. The goal of ...
Zhou B H - - 1998
The ability of the cat's ankle joint to track various input signals when controlled by electrically elicited motor unit recruitment, firing rate and antagonist muscle coactivation was examined. Pseudo-random, sinusoidal and staircase signals were used to control the soleus and tibialis anterior muscles isometrically and with a 250-g pendulum. Tracking ...
Pidcoe P E - - 1998
Past approaches for inducing protective stepping to preserve standing balance in humans have either lacked the flexibility of control over the initial conditions of falling, or involved considerable mass which limits mobility of the system. This report describes the design and function of a stepper motor closed-loop waist-pull system for ...
Baratta R V - - 1998
Models of skeletal muscle based on its response to sinusoidal stimulation have been in use since the late 1960s. In these methods, cyclic excitation at varying frequencies is used to determine force or muscle length amplitude and phase as functions of excitation frequency. These functions can then be approximated by ...
Fathallah F A - - 1998
STUDY DESIGN: An electromyogram-assisted free-dynamic lifting model was used to quantify the patterns of complex spinal loads in subjects performing various lifting tasks. OBJECTIVES: To assess in vivo the three-dimensional complex spinal loading patterns associated with high and low risk lifting conditions that matched those observed in industrial settings. SUMMARY ...
Sugi H - - 1998
Although a contracting muscle regulates its energy output depending on the load imposed on it ("Fenn effect"), the mechanism underlying the load-dependent energy output remains obscure. To explore the possibility that the mechanical efficiency, with which chemical energy derived from ATP hydrolysis is converted into mechanical work, of individual myosin ...
Wren T A - - 1998
The geometric and material properties of tendons and ligaments change during growth and development. While some of the changes occur in the absence of mechanical loading, normal development requires the mechanical stimulus provided by normal physical activity. We have developed an analytical framework for quantitatively describing changes in uniaxial tendon ...
Kaigle A - - 1998
The dynamic axial stiffness of the L2-3 motion segment subjected to vibratory loading under intact and injured states of the intervertebral disc was studied using an in vivo porcine model. Three groups of animals with the following states of the intervertebral discs were studied: intact disc, acutely injured disc, and ...
Sharma M - - 1998
A finite element (FE) based scheme for modeling facet articulation in a spinal motion segment is proposed. The algorithm presented models the facet articulation as a nonlinear progressive contact problem. This algorithm is used to perform a nonlinear FE analysis of a complete L3-L4 motion segment. The role of facets ...
Beebe D J - - 1998
This paper presents a silicon-based force sensor packaged in a flexible package and describes the sensors performance on human subjects. The sensing element consists of a circular silicon diaphragm (200-micron thick with a 2-mm radius) over a 10-micron sealed cavity with a solid Torlon dome providing force-to-pressure transduction to the ...
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