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A Delisle

Publications and source records attributed to A Delisle.

5 recordsLinked to original sources
PubMed2002

Handling missing marker coordinates in 3D analysis.

The use of mathematical formulations to retrieve missing data is not usually implemented as an automated computer procedure. The purpose of this paper is to present a simple mathematical formulation that can be used to retrieve the coordinates of markers hidden during a task. A strategy based on the smoothness of the variation of distance between points is devised, which leads to an automated computer procedure for retrieving hidden skin markers or missing joint coordinates (missing 3D points). This approach has the advantage of not being restricted to the usual rigid-body assumption.

Algorithms↗
PubMed1997

Effect of pelvic tilt on lumbar spine geometry.

The purpose of this study was to use a noninvasive method to determine the effect of pelvic tilt on the lumbar spine geometry in the sagittal plane. Five healthy male subjects were instructed in performing active forward and backward pelvic tilt manoeuvres in the standing position. The lumbar spine geometry (severity of lordosis, pelvis and lumbar vertebrae orientations) was estimated with a lumbar spine geometric model. The voluntary backward pelvic tilt succeeded in reducing the depth of the lumbar spine curvature, but the forward tilt did not change it. Both pelvic tilt manoeuvres influenced the absolute orientations of the lower lumbar vertebrae and the relative orientations of some lumbar vertebrae. Interestingly, the L5/S1 joint showed was little affected by the pelvic tilt manoeuvres.

Adult↗
PubMed1996

Handgrip and Box Tilting Strategies in Handling: Effect on Stability and Trunk and Knee Efforts.

The purpose of this study was to evaluate the effect of four handgrip-box tilting strategies (right, left, backward, and no tilt of the box) on trunk and knee efforts, body posture, and the stability of 14 participants with limited experience in handling. The tasks consisted of transferring a low-lying box placed in front of the participant to a shelf of the same height at the participant's left. It was hypothesized that tilting the box could reduce trunk and knee efforts as well as body asymmetry, and improve stability. A tridimensional dynamic rigid body model was used to estimate the triaxial net muscular moment magnitudes at the trunk (L5/Sl) and at the knees. An approach to quantify the participants' dynamic stability was also included. Finally, 5 angles were computed to characterize body asymmetries. The results showed that tilting the box affected specific trunk efforts, but did not succeed in reducing trunk asymmetric efforts. However, the tilts were executed in a single direction, and it may be possible that combined tilts of the box could help reduce trunk asymmetric efforts. Tilting the box had little effect on knee loadings, and the left tilt strategy reduced participants' stability. This study showed the importance of considering the position of the box when assessing the risks encountered in asymmetrical handling.

Journal Article↗
PubMedDate not supplied

[3-wheeled and 4-wheeled all-terrain vehicles: unstable and dangerous vehicles].

We present the results of a questionnaire completed by 526 victims of accidents involving three- and four-wheeled all-terrain vehicles. All victims were treated at the emergency departments of 10 regional hospitals in Quebec. In 70% of cases, the vehicles overturned. Two thirds of victims were injured in accidents without collision, typically involving overturns on level ground or hills. We suggest accident reconstruction research as a means of identifying engineering solutions as one element in an injury control approach.

Accidents↗