Telemetering of biomedical data from unrestrained subjects requires a system to be compact, reliable and efficient. A survey of the existing multi-channel biomedical telemetry showed that most of the systems employ analogue or uncoded (digital) techniques of encoding biomedical signals. These techniques are less reliable, employ wider bandwidth and are difficult to implement compared to the coded (digital) techniques of modulation. A theoretical study of the coded techniques of modulation for encoding biomedical signals showed-that pulse code modulation, though more efficient, calls for extensive circuitry and makes it expensive and difficult to implement. Delta modulation and delta sigma modulation were found to be simpler, easier to implement and efficient.

The research presented in this thesis investigated the relationship between deposited fingerprints and body size. The application of the research is the prevention of artificial fingerprint usage to bypass existing biometric fingerprint systems, contributing to an increase in the strength of their security. An anthropometric survey of finger, hand and body size was conducted to investigate the relationship between body size and finger size (n=89). Body measurements were found to correlate well when grouped according to two groups, skeletal length dimensions including stature and limb lengths, and skeletal width dimensions, including limb breadths and depths. Correlations as high as 0.9 were found within these groups. Factors found influential upon correlation strength include gender and the proximity of the limbs: for example, finger length has a higher correlation with hand length than with stature.

Photoplethysmography, a technique to measure by optical means volume changes, has been known and applied for many years. One of its most popular applications is pulse oximetry, a non-invasive method to measure oxygen content in arterial blood. It is based on the principle of arterial blood volume changes due to heart contractions, known as systoles. Systolic pulsations appear on the arterial vascular system, while blood flow in veins does not normally present pulsations, especially at remote parts of the peripheral vascular system, such as the fingers. Therefore, pulse oximetry is only applicable to arteries as their pulsations allow for separation of the pulsatile components from the rest of the absorbing components. A novel non-invasive technique permits the measurement of venous oxygen saturation by introducing a series of pulsations in the veins thus allowing the separation of venous signal components for calculation of venous oxygen saturation. This thesis presents a theoretical model describing the mechanical coupling of arteries and veins and its effects in the accuracy of oxygen saturation measurement.

The aim of this research was to report the physiological demands of America's Cup yacht racing. The nature of racing was quantified, specifically the activity pattern and exercise intensity, and the anthropometric, and fitness characteristics of the athletes documented. This included physiological assessment (aerobic power and anaerobic power) of the athletes during' grinding' (standing arm-cranking) the primary activity of America's Cup sailing. The influence of crank velocity, crank length, crank-axle height and the role of the lower limbs were evaluated in order to determine the conditions for optimal power production during grinding. The acute thermoregulatory responses to racing were assessed, and the chronic responses to training in terms of upper respiratory infection (URI), salivary-immunoglobulin A (s-IgA) and subjective fatigue documented. The exercise intensity of racing was high, but intermittent, and influenced by how evenly matched the boats were and the role of the athlete.

No description available.

Synaptosomes (isolated nerve-endings) have been prepared from the rat cerebral cortex according to Bradford et al. (1975) and used to study the effects of anoxia and hypoxia on cerebral metabolism. Experiments using a Rank oxygen-electrode have shown that synaptosomes behave in a manner reflecting the presence of the intra-synaptosomal mitochondria when placed in a mitochondrial incubation medium, e.g. (1) they respond to the addition of ADP by increasing O2 consumption when supported by exogenous respiratory substrates such as glutamate and succinate, but not to the extent expected of pure mitochondria, (2) hjrpotonic shock reduces O2 consumption and does not improve the ADP response, (3) ADP stimulation is blocked by oligomycin which can be overcome by DNP, and (4) the presence of a Na+, K+-ATPase in the synaptosomal limiting membrane is indicated by increased O2 consumption on addition of Na+ which is reversed by ouabain. Synaptosomes behave in a similar manner in a hypoxic medium ([O2] 4muM) as in anair-saturated Krebs phosphate medium, e.g. (1) a critical O2 concentration of 4muM was found where O2 consumption became dependent on the PO2 below this concentration, regardless of the initial PO2 , and (2) glucose and bovine serum albumin stimulate O2 consumption though by different, independent means. Any pre-incubation of synaptosomes should be carefully considered as should the composition of the medium since they will determine the rate of O2 uptake. There is no evidence that anoxia and hypoxia alters the accumulation and distribution of long-chain fatty acids and the increased respiration and glycolysis in a Ca2+-free medium indicates the dependency of cerebral metabolism on the Ca2+ concentration in hypoxia. It is concluded therefore that other oxygen-dependent processes such as monoamine synthesis, are responsible for the behavioural and functional alterations occurring at degrees of hypoxia too mild to affect ATP production.

A novel form of nutritional ketosis has recently emerged, based on the consumption of a ketone ester, that has the potential to impact upon sports performance. Ketone bodies are not normally present in the diet in more than trace amounts and are only produced in significant quantities physiologically during times of extreme energetic stress, but appear to be a highly efficient fuel source. The presence of elevated levels of ketone bodies in the absence of calorie deficit is highly novel and represents a fascinating metabolic state both for the examination of substrate selection during exercise and for the potential to impact sports performance. This PhD programme examined the utility of nutritional ketosis in sport by exploring the evidence base for its impact upon exercise performance and examining the translation of this knowledge into interventions in the field during real world sports performance. Study 1 (Chapter 3) established guidelines for dosing by demonstrating that consuming a meal in close proximity to ketone ester dosing (within 30-minutes (F30) compared to 90-minutes (F90)) resulted in a lowering of the area under the curve for ketone body concentration in the 90-minutes post dose (AUC-BHB(0-90), F90 v F30: 260.7 ± 33.6 mmol/l ̊min v 201.9 ± 33.4 mmol/l ̊min; P < 0.05) and that reducing the carbohydrate content of the ketone ester drink (F4:1) resulted in an increased accumulation of circulating ketone bodies (AUC-BHB(0-90), F90 v F4:1: 260.7 ± 33.6 mmol/l ̊min v 311.4 ± 49.3 mmol/l ̊min; P < 0.05) . Study 2 (Chapter 4) showed that low-dose ketone ester consumption had no effect on long duration cycle performance (20km TT, KET v CHO: 1731.3 ± 113.0s v 1736.9 ± 114.2s; P=N.S.) in contrast to prior evidence for performance impact at higher doses, suggesting that there may be a threshold of nutritional ketosis required to confer ergogenic benefit. In study 3 (Chapter 5) the hormonal response to repeat sprint cycling performance was characterised with transient increases in both testosterone and the more potent androgen dihydrotestosterone (DHT) occurring in response to sprinting. This served as a backdrop to study 4 (Chapter 6) which examined the impact of nutritional ketosis on sprint performance and showed that ketone ester consumption impaired repeat sprint cycling performance (average sprint power, KET v CHO: 507.3 ± 73.3W v 518.1 ± 72.9W; P < 0.01) alongside a dampening of the hormonal response that correlated with the performance deficit (r = 0.538; P = 0.047). Finally study 5 (Chapter 7) explored the translation of these findings into field interventions in sport through a case study series demonstrating that dietary ketone ester consumption is achievable during sports training and competition, leading to sustained nutritional ketosis, but that this comes with a significant side effect profile, poor adherence by athletes (31% withdrew from trialling due to perceived side effects of the drink and 26% withdrew from trialling due to a perceived lack of efficacy) and equivocal effects on performance. This work provides novel insight into the metabolic effects of nutritional ketosis in highly trained athletes whilst also highlighting the importance of taking a wider psycho-physiological perspective when translating experimental findings into application for real world sports performance. When considering the potential utility of ketone ester consumption during exercise there may be a narrow window between efficacy and intolerance and much to be determined regarding the conditions under which nutritional ketosis can impact sports performance.

Le travail de cette thèse est né suite aux résultats récents que 77% des patients amputés du membre supérieur ont un membre fantôme mobile. L’équipe de chercheurs dans laquelle ce présent travail est fait a montré que les contractions musculaires associé au membre fantôme peuvent être utilisées pour le contrôle de prothèses. Cependant, (1) ce contrôle « basé fantôme » est pour l’instant validé en contexte de laboratoire, et (2) les phénomènes entourant les membres fantômes sont encore mal compris. Ce travail de thèse CIFRE a visé à élaborer des matrices d'électrodes fines afin de détecter les activités musculaires associées aux mouvements fantômes pour (1) les incorporer dans l’emboiture de la prothèse afin de pouvoir faire des tests avec des prothèses portées, et (2) d’explorer les présumées réorganisations neuromusculaires au niveau du membre résiduel. Ces objectifs ont amené à développer et tester des électrodes fines et sèches sur divers supports : le Kapton, le papier, le textile et le tattoo temporaire. Cette étude exhaustive de supports a été permise par l’utilisation couplée d’un polymère conducteur apprécié dans la littérature actuel, le PEDOT :PSS, pour la fabrication d’électrodes et d’une méthode de fabrication par jet de matière. Enfin, divers méthodes d'analyses des signaux électromyographiques ont été étudiées. Pour conclure, ces travaux ont permis de diversifier les techniques et matériaux de création d’électrodes sèches et permettront enfin les tests de contrôle basé « mouvement fantôme » de prothèses myoélectriques portées, ainsi que l’étude la réorganisation des jonctions neuromusculaires du membre résiduel après amputation du membre supérieur. / The present work has its origin in recent results showing that 77% of upper limb amputees declare having phantom limb mobility. The team conducting this project was able to develop a method of controlling myoelectric prostheses based on the muscle contractions linked to phantom limb mobility. However, (1) this phantom-based mode of control is only validated in a laboratory setup without actually wearing the prosthesis on the residual limb, and (2) while it seems possible to use phantom mobility, we are still far from understanding it’s neurophysiological origin. The present work aimed to develop matrices of thin dry electrodes in order to (1) allow the creation of an embedded prosthesis with phantom-mobility-based control, and (2) explore the possible reorganization of motor endplates in the residual limb. These goals leaded to the fabrication of electrodes on multiple substrates. Kapton, paper, Textile and temporary tattoos were invistigated. The possibility to work on such different substrates was permitted by a biocompatible conducting polymer, PEDOT:PSS, used for the fabrication of the electrodes, and the use of inkjet printing technology. The dry electrodes were characterized and compared to wet Ag/AgCl electrodes (containing conducting gel) commonly used in electrophysiological recordings. For the latter, algorithms for the detection of innervations zones, developed in the literature, have been studied. In conclusion, the present thesis contributed to the diversification of technics and materials used for the creation of dry electrodes, and now opens the study of reorganization of innervation zones in residual limb muscles after upper limb amputation.

La conduite automobile requiert la mobilisation des ressources cognitives et physiologiques. Ainsi, détecter si le conducteur est somnolent ou même prédire dans combien de temps il risque de le devenir sont des défis importants pour le développement de nouveaux systèmes d’aide à la conduite. La somnolence, état intermédiaire entre le sommeil et la veille, représente un état dégradé et affecte donc potentiellement les performances de conduite. Ces travaux s’intéressent à la modélisation de la somnolence au volant grâce à des réseaux de neurones artificiels (ANN) et à l’aide de mesures physiologiques (rythme cardiaque et respiratoire), comportementales (mouvement des paupières et de tête) et à l’activité et performances de conduite. La première étude a montré qu’un ANN peut détecter le niveau de somnolence compris entre 0 et 4 (alerte à extrêmement somnolent) avec une racine carrée de l’erreur quadratique moyenne (REQM) de 0,40, mais aussi prédire dans combien de temps un état dégradé risque d’arriver avec une REQM de 2,23 min. Le temps de conduite et les informations personnelles permettent d’accroître les performances. Puis, ces modèles ont été testés sur un nouveau conducteur, mais de mauvaises performances sont observés. Ainsi, Un ANN a été entraîné sur un ensemble de conducteurs, puis il a été adapté à un nouveau conducteur, jamais vu avant par le ANN, grâce à ces premières données d’enregistrement. Grâce à cette adaptation personnalisée du ANN, une amélioration des performances de 40 et 80% est observé pour la détection et la prédiction de la somnolence au volant respectivement. Cette adaptation est une première réponse au problème de la variabilité interindividuelle. / Driving a car is a requiring full mobilization of physiological and cognitive resources to maintain performance. Detecting when the driver is drowsy but also predicting when the driver’s operational state begins to degrade has become one ambitious challenge for the development of new Advanced Driving Assistance Systems. Drowsiness, the intermediate state between sleep and awake, represents an impaired state for driving and its potential effect on the driving performance. This work focuses on developing a driver drowsiness model by using artificial neural networks (ANN) and physiological measures (heart and respiratory rate and their variability), behavioral (eyelids and head movement) and driving and performance activity (speed, time-to-lane-crossing, speed, steering wheel angle, position on the lane). The first study shows that a model can detect the level of drowsiness between 0 and 4 (alert and extremely drowsy) with a root mean square error (RMSE) of 0.4 and also predict when the impaired state will occur with a RMSE of 2.23 min. The driving time and personal information can enhance the performance. These models were then tested on a different participant, but in this case, we observe poor generalization performance. We then tested a personalized adaptation of this ANN, where the ANN was trained on a group of drivers and then adapted to a new driver. With this personalized adaptation of the ANN, we observe a performance improvement of 40% and 80% for the detection and the prediction of driver drowsiness respectively. This personalized adaptation process to the first data recorded is an initial response to the problem of inter-individual variability.

No description available.