No description available.

This thesis analyzes the wrist joint of the human hand by using a realistic threedimensional wrist model. Load distributions among carpal bones, forces on ligaments and joints were examined by using three-dimensional model. Wrist injuries and required surgical operations were examined with the model. The most crucial point of the study was that, using three-dimensional model of the wrist, hand surgeons would be able to predict results of surgical operation. Surgery planning may be done and mechanical results may be Evaluated on the wrist model.

The lack of detailed descriptions makes positive identification of individual bones of the human hand difficult. In some instances, labelled photographs and line diagrams depicting a few anatomical features are available in the literature while in other cases, unlabelled photographs and diagrams are provided. Textbooks generally describe each hand bone as having a head, shaft and base. The morphology of metacarpals is more commonly described than that of the phalanges. Thus, identification and siding of hand bones are rare, which excludes them from use in many forensic cases. Forensic anthropological studies also include the determination of demographic characteristics such as stature and sex. Parts of the human skeleton that are accurate predictors in determining stature and sex include the skull, pelvis, femur and tibia. Hand bones are often excluded from such studies due to their relatively small size and poor preservation. The aims of this study were firstly, to provide detailed morphological descriptions of metacarpals and phalangeal bones of the human hand; secondly, to develop regression formulae for stature using the hand bones and thirdly, to develop discriminant function formulae in which the hand bones can be used to determine the sex of an unknown individual. The study comprised 200 sets of hands of South African individuals. The results indicate that there are morphological features of individual bones of the human hand that can be used to identify and side them. Regression formulae have been devised whereby the length of a hand bone can be regressed to that of a long bone, which in turn can then be used to determine stature. The sexing accuracy, using the bones of the hand, is high for males and females. Average accuracies recorded were more than 80% in most cases, and more than 75% in all cases. Analyses of human hand bones can thus add valuable information when assessing skeletons of unknown individuals. / Thesis (PhD)--University of Pretoria, 2010. / Anatomy / unrestricted

La thématique de la thèse est très vaste. Sont présentées les grandeurs cinématiques locales ou régionales qui agissent sur le corps humain. La deuxième partie de la thèse décrit les méthodes optiques, par lesquelles on peut mesurer les vibrations produites par les machines-outils sur le système humain main-bras au cours de l'activité au travail. Dans la troisième partie sont donnés les effets négatifs des vibrations qui se produisent sur le système humain main-bras pendant l'exposition aux vibrations. La quatrième partie de cette thèse contient la base théorique des techniques optiques utilisées pour mesurer les vibrations. Le chapitre cinq présente la méthodologie d'expérimentation pour mesurer les vibrations. Les résultats des mesures sont indiqués dans le sixième chapitre de la thèse. Dans le chapitre sept on présente la modélisation mécanique et mathématique du système humain main-bras avec trois degrés de liberté et le dernier chapitre contient les conclusions finales. / In the first part of the doctoral thesis are presented the local and global kinematics sizes which are acting on the human body. This is followsed with the optical methods by which we can measure the vibrations produced by the machine-tools and them action on the human hand-arm system during the work activity. In the third part are given the effects of vibrations that occur on the hand-arm system during the exposure of vibrations. The fourth part of this thesis contains the theorical basis of optical techniques used for vibrations measurement. Chapter five presents the experimental methodology of vibrations measurement in comparition betsween the two methods: classical and optical. The results of measurement are given in chapter six of the thesis. In chapter seven is given the mechanical and mathematical modeling of human hand-arm system with three degrees of freedom and the eighth chapter contains the final conclusions, the personal contributions and the future research directions.

No description available.

The response patterns of human stretch receptors in the finger extensor muscles of the forearm were studied using the microneurography technique. Single-unit recordings were obtained from one-hundred and twenty-four afferents. A procedure was developed to classify the units in muscle spindle primary afferents, secondary afferents, and Golgi tendong organ afferents. The procedure allows an objective and reproducible classification on the basis of the afferents’ responses to a series of tests which individually are non-conclusive. It was demonstrated that maximal twitch contractions can be elicited in the finger extensor muscles of the forearm, without causing undue discomfort to the subjects, or hazarding the single-unit recording. The response of the units to this test allowed, in most cases but not always, a separation in muscle spindle and tendon organ afferents. Thus the test was not adequate for an unequivocal classification. Three discrete response parameters were extracted from ramp-and-hold stretches, viz. the presence or absence of an initial burst and a deceleration response, and prompt silencing at slow muscle shortening. The distributions of the parameters were significantly different among the three unit types. These parameters which were pair-wise independent constituted a set of considerable discriminative power. It was shown that human muscle spindles have about the same static position sensitivity to fractional muscle stretch as previously found in animals. Stretch sensitization was demonstrated by rapid, repeated stretches of the muscle which enhanced the réponse to subsequent slow stretches of muscle spindles. Sensitization was different with primary and secondary muscle spindle afferents whereas Golgi tendon organ afferents never displayed stretch sensitization. One-to-one driving with small-amplitude sinusoidal stretches superimposed on ramp-and- hold stretches was almost exclusively seen with primary muscle spindle afferents, whereas secondaries seldom and tendon organ afferents never displayed driving. The afferent responses during slowly increasing isometric contractions and rapid relaxations were analysed. An increased discharge rate on relaxation was common among spindle afferents whereas it was never seen in tendon organs afferents. Two separate groups of spindles afferents were found with regard to fusimotor recruitment. The largest group was recruited at rather low and variable contractile forces whereas the smaller group was not recruited at all. The proportions of the three unit types, spindle primary, spindle secondary, and Golgi tendon organ afferents were estimated from a preliminary classification and the distribution of the eight response features were analyzed for each class of afferents. On the basis of these estimates and the response pattern of the individual unit Bayes’ theorem was used to calculate the probabilities that the unit was a spindle primary, a spindle secondary, or a tendon organ afferent. Estimates indicate that about 19 out of 20 muscle afferents are correctly classified when all eight features are analyzed. / <p>Diss. (sammanfattning) Umeå : Umeå universitet, 1988, härtill 6 uppsatser.</p> / digitalisering@umu

During dexterous manipulation with the fingertips, forces are applied to objects' surfaces. To achieve grasp stability, these forces must be appropriate given the properties of the objects and the skin of the fingertips, and the nature of the task. It has been demonstrated that tactile sensors in the fingertips provide crucial information about both object properties and mechanical events critical for the control of fingertip forces, while in certain tasks vision may also contribute to predictions of required fingertip actions. This thesis focuses on two specific aspects of the sensory control of manipulation: (i) how individual fingers are controlled for grasp stability when people restrain objects subjected to unpredictable forces tangential to the grasped surfaces, and (ii) how tactile sensors in the fingertips encode direction of fingertip forces and shape of surfaces contacted by the fingertips. When restraining objects with two fingers, subjects adjust the fingertip forces to the local friction at each digit-object interface for grasp stability. This is accomplished primarily by partitioning the tangential force between the digits in a way that reflects the local friction whereas the normal forces at the involved digits are scaled by the average friction and the total load. The neural control mechanisms in this task rely on tactile information pertaining to both the friction at each digit-object interface and the development of tangential load. Moreover, these mechanisms controlled the force application at individual digits while at the same time integrating sensory inputs from all digits involved in the task. Microneurographical recordings in awake humans shows that most SA-I, SA-II and FA-I sensors in the distal phalanx are excited when forces similar to those observed during actual manipulation are applied to the fingertip. Moreover, the direction of the fingertip force influences the impulse rates in most afferents and their responses are broadly tuned to a preferred direction. The preferred direction varies among the afferents and, accordingly, ensembles of afferents can encode the direction of fingertip forces. The local curvature of the object in contact with the fingertip also influenced the impulse rates in most afferents, providing a curvature contrast signals within the afferent populations. Marked interactions were observed in the afferents' responses to object curvature and force direction. Similar findings were obtained for the onset latency in individual afferents. Accordingly, for ensembles of afferents, the order by which individual afferents initially discharge to fingertip events effectively represents parameters of fingertip stimulation. This neural code probably represents the fastest possible code for transmission of parameters of fingertip stimuli to the CNS.

This thesis is written as an essay, which considers sculpture outside of its definition as art object. Having as its goal finding an intrinsic definition of sculpture, the essay sets on a short journey meandering between ideas, historic precedents, and anecdotes. Among some of the discussed thing are: necessity, labor, leisure, Olduvai chopping stone tool, making, human hand, brain, body, pineal gland, third eye, speculation, materiality, Dixie cup, objecthood, sign, imagination, ENIAC, immateriality, myth, labor, leisure, storytelling, alien, alienation, destruction, creativity, genius, death, weed. The essay concludes that sculpture does not need a definition.

This thesis presents the preliminary work in the development of a biomimetic actuation mechanism for prosthetic and wearable robotic hand applications. This work investigates the use of novel artificial muscle technology, namely, shape memory alloys. The mechanism developed is based on the combination of compliant tendon cables and one-way shape memory alloy wires that form a set of agonist–antagonist artificial muscle pairs for the required flexion/extension or abduction/adduction of the finger joints. For the purpose of this thesis, an anthropomorphic four degree of freedom artificial testbed was developed with the same kinematic properties as the human finger. Hence, the size, appearance and kinematic architecture of the index finger were efficiently and practically mimicked. The biomimetic actuation scheme was implemented on the anthropomorphic artificial finger and tested, in an ad-hoc fashion, with a simple microcontroller-based pulse width modulated proportional derivation (PWD-PD) feedback controller. The tests were done to experimentally validate the performance of the actuation mechanism as emulating the natural finger’s joints movement. This thesis details the work done for the finger design process as well as the mechanisms and material used to achieve the actuation and control objectives. The results of the experiments done with the actuation platform are also presented.