ESTIMATING LUMBAR SPINAL LOADS DURING A GOLF SWING USING AN EMG-ASSISTED OPTIMIZATION MODEL APPROACH

This study estimated the lumbar spinal loads at L4-L5 level during a golf swing using musculoskeletal modeling techniques. Data were collected from five college golfers. Four S-VHS camcorders and two force plates were used to obtain 3-D kinetics and kinematics of the golfer’s motion and 10 surface electrodes were used to record the activity of selected lower trunk muscles. The EMG-assisted optimization model was used to estimate lower trunk muscle forces. The results demonstrate that the L4-L5 motion segment is subjected to considerable compressive (4,300 N), antero-posterior (A/P) shear (882 N), and medio-lateral (M/L) shear loads (-252 N) during a golf swing. The repetitive changing direction of the shear load during a golf swing may increase the chance of fatigue fracture of pars interarticularis. The results also suggest that a golf swing with shortened backswing and follow-through may reduce the risk of back injury

SPEED AND STROKE CYCLE CHARACTERISTICS DURING THE 100-M RACE FOR PARAPLEGIC ATHLETES

The purpose of this preliminary study was to evaluate the speed changes and selected stroke cycle characteristics during the 100-m wheelchair race for paraplegic athletes. Four male and two female T4 and one male and 3 female T3 wheelchair racers served as the subjects. Two S-VHS camcorders (60 fields/s) were panned horizontally to cover the first and second 50 m of the 100-m race, respectively. The maximum speeds recorded ranged from 5.53 m/s to 7.66 m/s. The distance and time needed to reach the maximum speed ranged from 43.9 m and 11.2 s (a T4 female) to 82.2 m and 18.9 s (a T3 female), respectively. The subjects in this study have lower maximum speeds than able-bodied runners and they need longer distance and time to reach their maximum speeds when compared their able-bodied counterparts

AN EXAMINATION OF RETURN TO PLAY CRITERIA FOR KNEE STRENGTH 1Nl EXPERIENCED SOCCER PLAYERS

Clinicians often use isokinetic strength exercises in the rehabilitation of lower extremity injuries. Isokinetic testing scores are often used as criterion to determine the progression within a rehabilitation protocol as well as the suitability of the patient to return to sport participation. For example, Shelbourne, Klootwyk, and De Carlo (1995) suggested that once the anterior cruciate ligament (ACL) reconstructed extremity achieves 70% of the strength of the uninjured leg, the patient is allowed to engage in sport-specific activities and begin the progression toward competitive participation. A criterion like this would be a valid standard assuming no strength differences exist between limbs. Few bilateral differences in lower extremity strength exist in most sedentary individuals or athletes participating in bilaterally symmetrical lower extremity activities. However, soccer players usually have tendencies to use one leg more than the other for dribbling, shooting and performing long kicks. As a result, soccer can be characterized as an asymmetrical lower extremity activity. If bilateral strength differences exist, then appropriate adjustments should be made for return to activity standards. This study examined whether differences existed in isokinetic knee f1exion and extension strength between the dominant and non-dominant legs in experienced soccer players

Lifetime Extension of RF MEMS Direct Contact Switches in Hot-Switching Operations by Ball-Grid-Array (BGA) Dimple Design

Direct contact RF microelectromechanical systems switches have demonstrated excellent ultrawideband performance from dc to 100 GHz. However, they are prone to failures due to contact adhesion and arcing, particularly for pure-gold/pure-gold contacts. In this letter, we present a new contact design employing ball grid array (BGA) dimples that limit the effective contact area to a few tens of nanometers in diameter. We experimentally show the performance of the BGA dimple with pure-gold/pure-gold contacts and demonstrate RF power handling greater than 1 W during hot switching in excess of 100 million cycles.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/87268/4/Saitou10.pd

Validation of a Predictive Model for Survival in Patients With Advanced Cancer: Secondary Analysis of RTOG 9714.

BackgroundThe objective of this study was to validate a simple predictive model for survival of patients with advanced cancer.MethodsPrevious studies with training and validation datasets developed a model predicting survival of patients referred for palliative radiotherapy using three readily available factors: primary cancer site, site of metastases and Karnofsky performance score (KPS). This predictive model was used in the current study, where each factor was assigned a value proportional to its prognostic weight and the sum of the weighted scores for each patient was survival prediction score (SPS). Patients were also classified according to their number of risk factors (NRF). Three risk groups were established. The Radiation Therapy and Oncology Group (RTOG) 9714 data was used to provide an additional external validation set comprised of patients treated among multiple institutions with appropriate statistical tests.ResultsThe RTOG external validation set comprised of 908 patients treated at 66 different radiation facilities from 1998 to 2002. The SPS method classified all patients into the low-risk group. Based on the NRF, two distinct risk groups with significantly different survival estimates were identified. The ability to predict survival was similar to that of the training and previous validation datasets for both the SPS and NRF methods.ConclusionsThe three variable NRF model is preferred because of its relative simplicity

EFFECTS OF ANKLE STABILlZATION ON PUSH-OFF MECHANICS FROM A THREE-POINT STANCE IN FOOTBALL

The purpose of this investigation was to examine the effects of taping and bracing on push-off mechanics from a three-point football stance. Nineteen males were tested under three ankle stabilization conditions: braced, taped, and control. Participants performed five trials in each condition. Two 250Hz video cameras and a forceplate were used to collect data. A MANOVA with repeated measures revealed a significant main effect for condition. Post hoc analysis indicated that bracing and taping resulted in reduced minimum and maximum ankle angles and maximum angular velocity compared to the control. The horizontal velocity of the center of mass at takeofffor the tape condition was significantly lower than the control. Bracing and taping can have a negative effect on push-off mechanics

The Undergraduate programme in prosthetic dentistry, 1996- 97

Includes bibliographical references (p. 58-66)published_or_final_versio

Contact Physics Modeling and Optimization Design of RF-MEMS Cantilever Switches

RF MEMS direct-contact switches exhibit many advantages over the conventional semiconductor switches; however, existing drawbacks such as low power handling, high pull-in voltage and long switch opening time are most critical. This paper presents an optimization design for an RF-MEMS cantilever direct-contact switch to achieve maximum power handling capability, minimum pull-in voltage and switch opening time simultaneously. A 2-step optimization technique is proposed to achieve the optimal design to allow for a power handling capability of 130 mW, a pull-in voltage of 52 V, and a switch opening time 4.4 _s presented. The optimization results show that substantial room exists for improving the current designs of RF MEMS direct-contact switches.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/87255/4/Saitou72.pd

DIRECTIONAL CONTROL IN TENNIS SERVES PERFORMED BY ELITE PLAYERS

This study quantified the pre-and post-impact 3-D kinematics of the ball and racquet during the serves that landed at different locations performed by five male and four female professional tennis players. Data were collected during competition using two high-speed cameras (200 Hz). Two first serves .-one landed near the center line and the other near the side line --were analyzed for each subject. A 2 x 2 ANOVA (0 < .05) was performed for each parameter. The results indicate that the males had significantly greater post-impact ball and racquet velocities than their female counterparts. Though not statistically significant, the ball tended to travel to the left less during the toss and have lower post-impact velocity for serves that landed near the side line. Altering the toss might be one of the strategies used by players to control ball direction in the serve