PubMed Health⌕ Search

Biomedical subjects

A Cappozzo

Publications and source records attributed to A Cappozzo.

32 records · Page 2Linked to original sources
PubMed1983

Comparative evaluation of techniques for the harmonic analysis of human motion data.

Four mathematical techniques for the estimation of the Fourier coefficients of pseudoperiodic non-exact discrete functions were submitted to comparative evaluation. These techniques were devised within the following basic procedures: (1) numerical harmonic analysis applied either directly or after redistribution of the data points through some interpolation procedure, so that they be evenly spaced in time and exactly fit on cycle period; (2) fitting of the empirical data with an analytical model followed by the calculation of the Fourier integrals of this model. The evaluation was carried out with special reference to the use of these techniques for processing human motion photogrammetric data. The following criteria were used: (1) accuracy of the Fourier coefficient estimates, (2) capability of yielding information about this accuracy, (3) a priori information needed regarding the statistical properties of the experimental error, (4) factors concerning implementation in digital computers. Practical information was obtained for the non-specialist user with regard to the choice of one technique among the several possible in particular circumstances.

Fourier Analysis↗
PubMed1983

The forces and couples in the human trunk during level walking.

The intersegmental force and couple exchanged between upper and lower body across a transverse section passing through the fourth lumbar vertebra were estimated during level walking on a straight line at speeds ranging from 0.99 to 2.23 ms-1. This was done using 3-D kinematic information relative to the head, upper limbs, and upper torso, obtained through a stereophotogrammetric technique, and the relevant inertial parameters obtained using anthropometric measurements and estimation techniques provided in the literature. Twenty walking cycles of five normal adult male subjects were analysed. The intersegmental force and couple components are presented as referenced to both a laboratory and pelvic set of axes. Using these results some considerations are made concerning the variations which the overall trunk muscles effort undergoes because of mean walking speed changes. The muscular action on the trunk is inferred from the intersegmental couple components. The various factors that contribute to the build-up of the intersegmental force and couple are analysed and their relative importance assessed.

Biomechanical Phenomena↗
PubMed1982

Low frequency self-generated vibration during ambulation in normal men.

An assessment was made of the upper body low frequency steady-state vibration in five normal male subjects during level walking in a straight line. Speed of progression ranged from 0.99 to 2.35 m/s. Through a stereophotogrammetric technique, a three-dimensional measurement of the linear displacement of the longitudinal axis of the trunk and head was done. The relevant accelerations were obtained by double differentiation and described both in the time and frequency domains. The data were compared with those available on the biodynamic properties of body tissues and on the subjective response of humans to externally generated whole-body vibration. The comparison yielded a consistent indication of the characteristics of the vibration stimulus to which the human body may be adapted. As walking speed approached its maximum, the vertical acceleration spectrum increased in magnitude and shifted critically close to frequencies at which body organs are known to undergo resonance. A coordinated movement of the trunk with respect to the pelvis helped to reduce to a minimum the value of the acceleration to which the head was submitted in the antero-posterior direction and to shift the relevant spectrum towards the lower frequencies.

Biomechanical Phenomena↗
PubMed1982

Angular displacements in the upper body of AK amputees during level walking.

The angular displacements of the longitudinal axis of the trunk, and of the latero-lateral axes of pelvis and shoulder girdle were measured in five normal subjects and four AK amputees during level walking at different speeds. Amputees used single axis prostheses with the SACH foot. Spatial measurements were carried out in three dimensions by means of a photogrammetric technique. The time functions of the target angles underwent harmonic analysis. Based on the Fourier coefficients, comparison was made between normal subjects' and amputees' angular displacements. Relevant findings permitted the identification of compensatory mechanisms adopted by amputees at trunk level as well as the assessment of the relationship between these latter mechanisms and those put into action at lower limb level.

Amputation, Surgical↗
PubMed1977

Evaluation of hip arthroprostheses by means of body environment simulators.

Laboratory tests carried out by means of body environment simulators have proved to be very important for the evaluation of endoprostheses potentially useful for implantation. The present paper examines the problems connected with the design of such a simulator. The results obtained with an initial, very primitive simulator concerning the outlines of the phenomena of wear, corrosion, and friction and some wear properties of commercially available hip endoprostheses are presented. From these results, the motivation that led to the design of a more advanced simulator is presented. This latter simulator is also described.

Corrosion↗