Thesis (M.S.)--Montana State University--Bozeman, 2007. / Typescript. Chairperson, Graduate Committee: Alexander V. Zale. Includes bibliographical references (leaves 93-103).

Thesis (M.S.)--Montana State University--Bozeman, 2007. / Typescript. Chairperson, Graduate Committee: Alexander V. Zale. Includes bibliographical references (leaves 84-96).

Diss. Uppsala : Sveriges lantbruksuniversitet, 2005.

Thesis (Ph. D.)--University of Wyoming, 2006. / Title from PDF title page (viewed on June 30, 2008). Includes bibliographical references (p. 96-98).

Thesis (M. Sc.)--University of Hong Kong, 1994. / "Individual workshop 1994 (Part time)." Maps in pocket. Includes bibliographical references.

Thesis (M.S.)--University of Wisconsin--Madison, 1967. / eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Thesis (M.S.)--Montana State University--Bozeman, 2005. / Typescript. Chairperson, Graduate Committee: Alexander V. Zale. Includes bibliographical references (leaves 70-78).

<p>The semicircular canals of the vestibular system detect angular head rotations and play a fundamental role in guiding motor reflexes during locomotor behaviors. While extensive research has documented the relationship between the semicircular canal shape (i.e. radius of curvature and canal length) and locomotor behaviors, levels of intraspecific variation in primates are relatively unknown. Predictive models using these metrics to reconstruct locomotion in extinct animals are generally based on one individual per species. Furthermore, the influence of body size and to a lesser degree brain size heavily influences overall canal morphology.</p><p>This study documents intraspecific variation in the size, shape and orientation of the semicircular canals in relation to changes in function, brain size, and body size via analysis of high resolution CT scans of large samples of extant primate species. I test the hypothesis that the extent of intraspecific variation differs across a sample of primates, reflecting the intensity of selective pressure on canal shape in species that require agility during locomotion. I also examine whether spatial constraints resulting from the size of the skull (reflected by the size of the brain) affect canal radii of curvature and canal orthogonality more strongly than observed agility during locomotion. </p><p>To this end, data was gathered from high-resolution CT images of museum specimens. For the comparative analysis, 14-matched pairs of adult extant primate species were selected that contrast in agility and brain size in closely related genera. CT images of these specimens were used to measure functional measures of canal sensitivity (e.g., canal radii of curvature, orthogonality). This data was used to test hypotheses concerning intraspecific and interspecific variation in semicircular canal functional morphology. This data was then combined with a larger mammalian dataset culled from the literature, to further test hypotheses relating to body-size and brain size dependent variation in individual canal metrics. </p><p>Evaluation of levels of intraspecific variation support the hypothesis put forth by Billet et al. (2012), that selection on canal morphology is relaxed in animals with slow locomotor behaviors, who are observed to have higher levels of intraspecific variation. Analyses of interspecific variation provides tentative support for the use of canal orthogonality in reconstructive models, most especially in canal angles that seem least effected by other constraints—brain size, etc. However, locomotor signals are complex and brain/skull interactions can potentially produce misleading results when reconstructing locomotor behaviors. This work highlights the importance of critically assessing comparative groups used for inferring behaviors in both extinct and extant animals.</p> / Dissertation

The objective of this study was to develop a numerical model which predicts the geometry of an optimal straight stable channel for a given set of conditions: (1) the submerged coefficient of static friction of the channel bed material, (2) lift-to drag ratio, (3) grain size of the bed material, (4) water discharge, and (5) longitudinal slope of the channel. The term optimal stable channel refers to a channel capable of transporting sediment along a flat bed but whose banks are barely stable, i.e., all particles lying in the bank region are on the verge of motion. In addition to the geometry of the optimal stable channel, the model determines the critical and actual stress distributions along the perimeter of the channel cross-section. The model is based on the turbulent diffusion concept, which takes into account the diffusion of downstream momentum from the center of the channel towards its banks, due to Reynolds stresses. This causes a redistribution of stress along the channel perimeter. The resulting shear stress decreases monotonically as the lateral distance from the center of the channel increases. With such a distribution, it is possible for the stress to be above critical in the flat bed region, and below or at critical in the bank region. Thus, it allows for the coexistence of a mobile bed and stable banks; a phenomenon commonly observed in natural streams and laboratory flumes but not possible to explain on the basis of the threshold channel theory. Special attention is given to the area in the vicinity of the junction of the bed and bank, because of a discontinuity in the curvature of the bank profile that exists right at the junction point. This discontinuity, or step function, has been ignored by other researchers, although it can significantly influence the shape of the bank profile. A dirac delta function is used here for the third derivative in order to remedy the problem. By numerically integrating the third derivative, the change in the step function at the junction point can be determined. Regime relations are proposed based on numerical model calculations. The results of the numerical model compare favorably with existing laboratory and field data. It was found that the banks of an optimal stable channel are closely described by a fifth degree polynomial, which differs from the cosine, exponential, and parabolic profiles suggested by earlier investigators. It was also determined that the geometry of a threshold channel differs from that of a wide channel. / Master of Science

Ossos, estruturas essenciais para a proteção de órgãos internos, estrutura corporal e suporte mecânico nos vertebrados, possuem uma complexa rede de canais (canais de Volkmann e Havers) responsáveis por nutrir as células do tecido. Entretanto a falta de estudos quantitativos leva a uma carência de medidas e parâmetros para a caracterização dessas estruturas. Utilizando computação gráfica, técnicas de processamento de imagens, e redes complexas descreveremos a obtenção, reconstrução, representação, e análise dessas redes de canais. Para isso, duas falanges distais, uma de um galo e uma de uma galinha, passaram por um processo de corte histológico, as lâminas resultantes foram fotografadas e as imagens tratadas até serem reconstruídas em 3D. Os volumes foram convertidos em redes complexas, o que permitiu o uso de métodos de análise consagrados pela literatura. As redes foram comparadas entre si e com a rede do trabalho desenvolvido por Matheus P. Viana et al. (1&ndash;3) usando análise de grau, posicionamento dos nós, detecção de comunidades, e ataques (em cascata e aleatórios). Três resultados se destacam: 1) as redes apresentam diviões predominantemente dicotômica dos canais; 2) as redes apresentam uma alta modularidade, indicando que áreas específicas desempenham funções específicas; e 3) as redes são particularmente resistentes a ataques em cascata. / Bones are essential for the protection of internal organs, for body structure, and for mechanical support in vertebrates, and present a complex network of channels (Havers and Volkmann channels) required to nourish tissue cells. However, the lack of quantitative studies leads to scarce parameters and measures to characterize these structures. By using computational graphic, image processing, and complex networks we will describe the acquisitation, reconstruction, representation, and analysis of these channel networks. Two distal phalanges (one from a hen and one from a rooster) were submitted to hystological section processing; the resulting slices were photographed and the images were treated before 3D reconstruction. The volumes were converted into complex networks which allow us to use methods of analysis widely accepted in literature. Networks were compared with each other and with the network obtained in the study by Viana et al. (1&ndash;3) using degree analysis, node positioning, community detection, and random and systematic attacks. Three results stand out: (i) the networks show a predominantly dichotomic division of channels; (ii) the networks show high modularity, indicating that specific areas perform specific functions; and (iii) the networks are particularly resistant to cascate attacks.