The Telemetered Measurement of Strain on the Surface of a Maxillary Denture in Function

This paper describes the development of a biotelemeter for the measurement of the strain on the surface of a complete maxillary denture. A thick film hybrid circuit has been developed giving up to three channels of strain data from three separate semiconductor strain gauges. The telemeter has a volume of approximately 1.5 cm3 and has been incorporated into a maxillary denture to provide functional assessment of the denture. Recordings of surface strain in the denture have been made from a subject while chewing various foods and these are presented together with a simple analysis of them.

Influence of acute endurance activity on leg neuromuscular and musculoskeletal performance

PURPOSE

The purpose of this study was to investigate the effect of endurance activities designed to simulate the physiological demands of soccer match-play and training, on leg strength, electromechanical delay, and knee laxity.

METHODS

Eight recreational soccer players completed four exercise trials in random order: 1) a prolonged intermittent high intensity shuttle run (PHISR) which required subjects to complete a total distance of 9600 m in a form simulating the pattern of physical activity in soccer match-play (activity mode; rest-to-work intervals; approximately 90 min duration), 2) a shuttle-run (SR), (3) a treadmill run (TR) which required subjects to complete an equivalent distance at a running speed corresponding to 70% VO2max, and 4) a control condition consisting of no exercise.

RESULTS

Results from repeated measures ANOVA revealed significant condition (PHISR; SR; TR; control) by time (pre; mid; post) interactions for peak torque (PT: knee extension and flexion: 1.05 rad.s-1), EMD and anterior tibio-femoral displacement (TFD) (P < 0.05). Impairment to indices of knee joint performance was observed in PHISR, SR, and TR trials. The greatest decrement occurred in PHISR and SR trials (up to 44%). Knee extensor and flexor strength performance near to full knee extension (0.44 rad knee flexion) was not changed following the functionally-relevant endurance activities.

CONCLUSIONS

Even though strength performance near to full knee extension was preserved following acute endurance activities, the risk of ligamentous injury may be increased by concomitant impairment to EMD and anterior TFD.

Critical appraisal and further development of the methodology for open circuit calorimetry in neonates

A non-invasive technique for open circuit calorimetry based on a Vickers 79 incubator as the gas collection chamber was developed and evaluated. The technique, which involved drawing air from the incubator hood at 11 1/min for gas analysis, did not have a significant cooling effect on the infant and the noise levels within the incubator did not exceed current safety standards. A new technique for checking the calibration of the whole system was developed as the traditional alcohol burn method proved unsatisfactory. Either pure oxygen or carbon dioxide were fed into the incubator hood at controlled physiological rates using a calibrated throttling valve. Over a number of calibration checks the mean error of the system proved to be +/- 4.3% for oxygen and +/- 4.45% for carbon dioxide. Less than a fifth of this error was attributable to the pump and flow meter. When oxygen is introduced to the system at a constant physiological rate it takes 30 min for a plateau to be reached. Therefore it is recommended that this system is used when readings are to be taken in a steady state situation or data is to be cumulated over a long period of time such as in an energy balance study. A run in period of 30 min before collecting data is essential. It is recommended that a calibration check is performed before each study.

Mechano-electrical properties of bone

Bone has been shown to exhibit ferro-electric properties. The relationship between applied electric field and polarization shows a hysteresis character typical of this type of material. This implies a domain structure for the permanent dipoles present in bone. Attempts to demonstrate semi-conductor properties were unsuccessful although a change of electrical resistance with applied tensile strain was demonstrated. No effect on conductivity of bone with change of pH of the fluid in which it was immersed was shown and hence no confirmation of streaming potential effects was obtained.