In the literature on postural control, many investigators have studied the movements of the body in one or several tasks and used the fixation task to provide baseline data to better understand their results (e.g., Kapteyn et al., 1983 ; Raymakers, Samson, & Verhaar, 2005 ). In this fixation task
Cameron Coates, Priya Goeser, Camille Coates-Clark and Mark Jenkins
The objectives of this work were to explore a methodology that combines static and dynamic finite element (FE) analysis, linear elastic fracture mechanics (LEFM) and experimental methods to investigate a worst-case scenario in which a previously damaged bone plate system is subjected to an impact load. Cadaver ulnas with and without midshaft dynamic compression plates are subjected to a static three-point bend test and loaded such that subcritical crack growth occurs as predicted by a hybrid method that couples LEFM and static FE. The plated and unplated bones are then unloaded and subsequently subjected to a midshaft transverse impact test. A dynamic strain-based FE model is also developed to model the midshaft transverse impact test. The average value of the impact energy required for failure was observed to be 10.53% greater for the plated set. There appears to be a trade-off between impact damage and impact resistance when ulnas are supported by fixation devices. Predictions from the dynamic FE model are shown to corroborate inferences from the experimental approach.
Thomas Hausegger, Christian Vater and Ernst-Joachim Hossner
different levels of motor expertise in French boxing (kickboxing). Besides expertise differences in decision making, they found that expert boxers mostly fixated on the opponent’s head, whereas less skilled boxers often fixated on the opponent’s arms and fists. In addition, experts’ fixations were longer
Oscar Martel, Juan F. Cárdenes, Gerardo Garcés and José A. Carta
Anterior cruciate ligament (ACL) reconstruction is one of the most important aspects of knee surgery. For this purpose, several fixation devices have been developed, although the interference screw is the most frequently used. The most typical biomechanical test of these devices consists of placing them in a testing machine and subjecting them to a pull-out test. However, insufficient attention has been paid to the influence of the displacement test rate on the mechanical properties of the fixation system. The aim of this study is to compare the influence of the crosshead rate in the biomechanical test of two different devices for the fixation of ACL tendon grafts. One hundred in vitro tests were performed using porcine tibiae and bovine tendons. The fixation devices used were (1) an interference screw and (2) a new expansion device. All ACL reconstructions were subjected to pull-out test to failure. Five crosshead rates were employed in a range from 30 mm/min to 4000 mm/min. Statistical analyses of the results show that, for the two devices, the rate has a significant effect on both maximum force and stiffness. Moreover, the new expansion device showed lesser dependency on the crosshead rate than the interference screw.
Melissa R. Taylor, Erin E. Sutton, Wiebke S. Diestelkamp and Kimberly Edginton Bigelow
The goal of this study was to examine the effects of 3 factors and their interactions on posturography: a period of time to become accustomed to the force platform before the initiation of data collection, presence of a visual fixation point, and participant talking during testing. The postural stability of 30 young adults and 30 older adults was evaluated to determine whether any observed effects were confounded with age. Analysis of variance techniques were used to test all possible combinations of the 3 factors. We hypothesized that all 3 factors would significantly affect postural stability. For both participant groups, the results suggest that a period of time to become accustomed to the force platform before the initiation of data collection and a visual fixation point significantly affect postural control measures, while brief participant talking does not. Despite this, no significant interactions existed suggesting that the effects of these factors, which may occur in clinical testing, do not depend on each other. Our results suggest that inconsistencies in posturography testing methods have the potential to significantly affect the results of posturography, underscoring the importance of developing a standardized testing methodology.
David Brown, Kyle Sanders, Drew Farrar, Joshua Newton, Adam J. Thompson and Andrew T. Doyle
Carrie B. McCloskey
Edited by Joe J. Piccininni
David O. Draper, J. Chris Castel and Dawn Castel
Melissa Hunfalvay and Nicholas Murray
, & Williams, 1999 ), cognition ( Williams & Grant, 1999 ), and long-term memory ( Reina et al., 2004 ). Past researchers have found that experts compared with novices have fewer fixations of longer duration (e.g., Perez, Mendez, Manzano, & Collado, 2013 ; Piras, Pierantozzi, & Squatrito, 2014 ), which
Aaron Manzanares, Ruperto Menayo and Francisco Segado
on perceptual-cognitive expertise ( Mann, Williams, Ward, & Janelle, 2007 ) describes the visual strategy of skilled athletes, stating that they have fewer fixations but with longer durations. This statement about the visual strategy of a skilled athlete is supported by several authors ( Ávila