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Biomedical subjects

J L Gilbert

Publications and source records attributed to J L Gilbert.

13 recordsLinked to original sources
PubMed1992

A computer-based biomechanical analysis of the three-dimensional motion of cementless hip prostheses.

A computer-based mathematical technique was developed to measure and completely describe the migration and micromotion of a femoral hip prosthesis relative to the femur. This technique utilized the mechanics of rigid-body motion analysis and apparatus of seven linear displacement transducers to measure and describe the complete three-dimensional motion of the prosthesis during cyclic loading. Computer acquisition of the data and custom analysis software allowed one to calculate the magnitude and direction of the motion of any point of interest on the prostheses from information about the motion of two points on the device. The data were also used to replay the tests using a computer animation technique, which allowed a magnified view of the three-dimensional motion of the prosthesis. This paper describes the mathematical development of the rigid-body motion analysis, the experimental method and apparatus for data collection, the technique used to animate the motion, the sources of error and the effect of the assumptions (rigid bodies) on the results. Selected results of individual test runs of uncemented and cemented prostheses are presented to demonstrate the efficacy of the method. The combined effect of the vibration and electrical noise resulted in a resolution of the system of about 3-5 microns motion for each transducer. Deformation effects appear to contribute about 3-15 microns to the measurement error. This measurement and analysis technique is a very sensitive and powerful means of assessing the effects of different design parameters on the migration and micromotion of total joint prostheses and can be applied to any other case (knee, dental implant) where three-dimensional relative motion between two bodies is important.

Biomechanical Phenomena↗
PubMed1990

Temporal clause comprehension in fluent and nonfluent aphasics.

Ten fluent and ten nonfluent aphasics participated in this study. Their ability to comprehend before and after clauses which mirrored the order of occurrence and those which did not mirror the order of events was investigated. Results indicate that type of aphasia was not a significant variable related to comprehension but that sentence type was a significant variable. Aphasics' comprehend before clauses better than after clauses. Nonfluent aphasics were able to comprehend those temporal clauses that mirror the order of occurrence better than those that do not. Order of mention was not a significant factor related to comprehension in the fluent group.

Adult↗
PubMed1987

[Endomorphines in schizophrenia].

The biological enigma of schizophrenia has led, on the basis of thin evidence, to widen the field of clinical research to a study of endomorphines in this disease. Too many different methods of measuring the levels of opiate peptides in the CSF have been used so that it is not possible to analyse the results statistically. Clinical trials of agonists and antagonists to the opiate receptors have once again emphasised the biochemical heterogeneity of schizophrenics but have not allowed any confirmation that the endorphinical system plays any part in the genesis or symptomatology of schizophrenia. The presence of sub-groups who respond positively to experimental treatment can lead to the hope, despite the uncertainties of their mode of pharmacological action, to the next advance in the routine treatment of schizophrenia.

Clinical Trials as Topic↗