Thèse (M.Sc.)--Université Laval, 2001. / Bibliogr.: f. 129-144. Publié aussi en version électronique.

Thesis--Doctor of Public Health. The University of Michigan, School of Public Health, Department of Epidemiology. 1966. / Includes bibliographical references.

Thesis (M.S.)--Ohio State University, 1975. / Includes bibliographical references.

Tracking multiple articulated objects (such as a human body) and handling occlusion between them is a challenging problem in automated video analysis. This work proposes a new approach for accurately and steadily visual tracking people, which should function even if the system encounters occlusion in video sequences. In this approach, targets are represented with a Gaussian mixture, which are adapted to regions of the target automatically using an EM-model algorithm. Field speeds are defined for changed pixels in each frame based on the probability of their belonging to a particular person's blobs. Pixels are matched to the models using a fast numerical level set method. Since each target is tracked with its blob's information, the system is capable of handling partial or full occlusion during tracking. Experimental results on a number of challenging sequences that were collected in non-experimental environments demonstrate the effectiveness of the approach.

Magister Scientiae Dentium - MSc(Dent) / The controversy surrounding the role of malocclusion and orthodontic treatment in temporomandibular joint (TMJ) dysfunction led to this study. The purpose of this study was to establish the prevalence and compare the status of signs and symptoms of TMJ dysfunction in four groups of adolescents and young adults. The groups consisted of 14 persons with normal occlusions, 23 with untreated malocclusions, 20 with malocclusions currently undergoing treatment, and 18 with treated malocclusions. The Helkimo index was used to collect the TMJ dysfunction data. The results showed that the untreated malocclusion group had the most number of persons with signs and symptoms of dysfunction, but the differences between the groups in the distribution of persons according to the anamnestic and clinical dysfunction indices were not statistically significant. There were also no statistically significant differences in the distribution of signs and symptoms between boys and girls. According to anamnesis, the most frequently reported symptoms were joint sounds and headaches or neckaches occurring more than twice a week. Amongst the clinical signs and symptoms, the most commonly occurring were joint sounds on auscultation and muscle tenderness on palpation. In light of the small study sample and the absence of any substantial differences between the four groups, the role of malocclusion and orthodontic treatment in the aetiology of TMJ dysfunction remains obscure. / South Africa

Indiana University-Purdue University Indianapolis (IUPUI)

Indiana University-Purdue University Indianapolis (IUPUI) / The purpose of this study was to provide information concerning occlusion and related problems in cerebral palsied children. A group of 124 cerebral palsied children between the ages of 6 and 12 years were examined at the Cerebral Palsy Dental Clinic, Indiana University. The occlusion was evaluated according to Angle's classification. In addition, a recording was made of overjet, over-bite, open bite, cuspid relationships, crossbite and midline discrepancies. The examination included a clinical evaluation of the swallowing pattern of each child. The cerebral palsy classification and I.Q. scores were recorded for each cerebral palsied child after a comprehensive review of his medical record. These findings were compared with a control group of 141 similar aged non-cerebral palsied children examined at Indiana University, Pedodontic department. The cerebral palsied group had an average increased overjet of 0.8 mm. and an average decreased overbite of 0.5 mm., representing an upward and outward positioning of the maxillary anterior segment. Anterior open bite was present in a similar percentage of both groups, but in the cerebral palsied group the measurement recorded was more than twice as great as that recorded in the control group. Forty-four per cent of the cerebral palsied children exhibited bruxism, more than twice the percentage of cases recorded in the control group. The cerebral palsied children exhibited bruxism most frequently in the day time, and was most common in the athetoid group. Other measurements recorded were not significantly different between the two groups. From this study one can conclude that malocclusion and factors affecting occlusion are not found with greater frequency in cerebral palsied children.

Indiana University-Purdue University Indianapolis (IUPUI) / It is believed that a single force, regardless of its magnitude, tips a tooth around the same center of rotation. This is a histologic investigation of this concept; and an attempt to correlate clinical findings with early and late microscopic changes in the periodontium after light and heavy force application. Five Rhesus monkeys, 3-4 years of age, were used. In one, continuous forces of 40 and 600 gm. were to move a maxillary first bicuspid distally through an edentulous space, with the first molar serving as anchor for 47 days. Both teeth tipped equally toward each other. In four monkeys, light, continuous forces, 10 and 57 gm., and heavy forces, 100 and 200 gm., were used to move the two central incisors lingually over periods of 19, 62, and 66 days. The light force had to be maintained for a period of 4-6 weeks before changing the activation. The 10 gm. force did not move incisors after 19 or 62 days. The 57 gm. force moved the tooth faster than the heavy forces. Hyalinization of the periodontal membrane was recorded during the lag period, but not later. At later stages, the heavy force caused more root resorption than the lighter one. The moment/force ratio determines the center of rotation, not the single value of each. Single forces tipped teeth at the same center of rotation, regardless of their magnitude.

Indiana University-Purdue University Indianapolis (IUPUI) / The tongue in both man and animal has been considered through the ages to be a complex organ. It is a highly specialized combination of muscles and nerves and contains one of the five senses, the sense of taste. As H.B. Walter and L.F. Sayles stated in their book entitled: “Biology of the Vertebrates,” “The tongue serves many purposes. It is capable of great freedom of movement; it is a universal toothbrush, serves as a curry comb for fur-bearers, while animals like cats and dogs that lap up liquids use it as a spoon, it stands ready to receive the password of admittance from entering food, and in humans is essential for speech, respiration and swallowing.” Even though the tongue is a complex organ in its actions and structure, it is unlike most organs of the human body. Man has not concerned himself to a great extent over its history of development for many reasons. It is encased by the orbicularis oris complex and buccinator muscles and teeth, thereby making ease of observation of its actions and development difficult. Another factor which acts against its observation for its apparent constant mobility. Most postulations previously set forth concerning the action of the normal tongue have been unsupported by scientific data. Studies have been reported on abnormalities of the tongue and its associated surroundings, but little or no research on the normal tongue posture has been reported. Recently roentgenography has been used to study areas of the body not easily seen by the naked eye. In the infancy of roentgenography development, it was considered by several investigators that this would be an important means of studying the tongue and thus this study came into being.

The main goal of this research is the automatic construction of a computer model of 3D solid objects from a single range image. This research has many real world applications, including robotic environments and the inspection of industry parts. The most common methods for 3D-object extraction are based on stereo reconstruction and structured light analysis. The first approach encounters the difficulty of finding a correspondence of points between two images for the same scene, which involves intensive computations. The latter, on the other hand, has limitations and difficulties in object extraction, namely, inferring information about 3D objects from a 2D image. In addition, research in 3D-object extraction up to this point has lacked a thorough treatment of overlapped (occluded) objects. This research has resulted in a system that can extract multiple polyhedral objects from a single range image. The system consists of several parts: edge detection, segmentation, initial vertex extraction, occlusion detection, grouping faces into objects, and object representation. The problem is difficult especially when occluded objects are present. The system that has been developed separates occluded objects by combining evidence of several types. In the edge detection algorithm, noise reduction for range images is treated first by implementing a statistically robust technique based on the least median of squares. Three approaches to edge detection are presented. One that detects change in gradient orientation is a novel approach, which is implemented in the algorithm due to its superior performance, and the other two are extensions of work by other researchers. In general, the performance of these edge detection methods is considerably better than many others in the domain of range image segmentation. A hybrid approach (region-edge based) is introduced to achieve a robust solution for a single range image segmentation. The segmentation process depends on collaborating edge and region techniques where they give complementary information about the scene. Region boundaries are improved using iterative refinement. A novel approach for initial vertex extraction is presented to find the vertices of the polyhedral objects. The 3D vertex locations for the objects are obtained through an analysis of two-dimensional (2D) region shape and corner proximity, and the vertices of the polyhedra are extracted from the individual faces. There are two major approaches for dealing with occlusion. The first is an automatic identification of layers of 3D solid objects within a single range image. In this novel approach, a histogram of the distance values from a given range image is clustered into separate modes. Ideally, each mode of the histogram will be associated with one or more surfaces having approximately the same distance from the sensor. This approach works well when the objects are lying at different distances from the sensor, but when two or more objects are overlapped and lying at the same distance from the sensor, this approach has difficulty in detecting occlusion. The second approach for occlusion detection is considered the major contribution of this work. It detects occlusion of 3D solid objects from a single range image using multiple sources of evidence. This technique is based on detecting occlusion that may be present between each pair of adjacent faces associated with the estimated vertices of the 3D objects. This approach is not based on vertex and line labeling as other approaches are; it utilizes the topology and geometrical information of the 3D objects. After occlusion detection, faces are grouped into objects according to their adjacency relations and the absence or presence of occlusion between them. The initial vertex estimates are improved significantly through a global optimization procedure. Finally, models of the 3D objects are represented using the boundary representation technique that makes use of the region adjacency graph (RAG) paradigm. The experimental results of this research were obtained using real range images obtained from the CESAR lab at Oak Ridge National Laboratory. These images were obtained using a Perceptron laser range finder. These images contain single and multiple polyhedral objects, and they have a size of 512x512 pixels and a quantization of 12 bits per pixel. A quantitative evaluation of the construction algorithms is given. Part of this evaluation depends on the comparison between the results of the proposed segmentation technique and the ground truth database for these range images. The other part is to compare the results of the implemented algorithms with the results of other researchers, and it is found that the system developed here exhibits better performance in terms of the accuracy of the boundaries for the regions of the segmented images. A subjective comparison of the new edge detection methods with some traditional approaches is also provided for the set of range images. An evaluation of the new approach to occlusion detection is also presented. A recommendation for future work is to extend this system to involve images contain objects with curved surfaces. With some modifications to the multiple evidence-based approach of occlusion detection, the curved objects could be addressed. In addition, the model could be updated to include representation of the hidden surfaces for the 3D objects. This could be achieved by using multiple views for the same scene, or through assumptions such as symmetry to infer the shape of the hidden portion of the objects. / Ph. D.