Thesis (Ph. D.)--University of Texas at Austin, 2000. / Vita. Includes bibliographical references (leaves 195-208). Available also in a digital version from Dissertation Abstracts.

Thesis (Ph. D.)--University of Texas at Austin, 2000. / Vita. Includes bibliographical references (leaves 222-229). Available also in a digital version from Dissertation Abstracts.

Cell adhesion to a substrate or another cell plays an important role in the activities of the cell, such as cell growth, cell migration and cell signaling and communication with extracellular environment or other cells. The adhesion of the cell to the extracellular matrix also plays a vital role in life, as it involves in healing process of a wound and formation of the blood clot inside a vessel. The spread of cancer metastasis tumors inside the body is mostly dependent on the mechanisms of the cell adhesion. The current work is devoted to studying deformation and adhesion of the cell membrane mediated by receptors and ligands in order to enhance the existing models. In fact phospholipid molecules as the constructive units of the cell membrane grant sufficient in-plane continuity and fluidity to the cell membrane that it can be acceptably modeled as a continuum fluid medium. Therefore a two dimensional isotropic continuum fluid model is proposed in here for cell under implementation of membrane theory. In accordance to lack of sufficient study on direct effect of presence of receptors on membrane dilation, the developed model engages the intensity of presence of receptors with membrane deformation and adhesion. This influence is considered through introduction of spontaneous areal dilation. Another innovation is introduced regarding conception of receptor-ligand bonds formation such that a nonlinear constitutive relation is developed for binding force based on charge-induced dipole interaction, which is physically admissible. This relation becomes also enriched by considering one-to-one shielding phenomenon. Diffusion of the receptors is formulated along the membrane under the influence of receptor-receptor and receptor-ligand interactions. Then the presented models in this work are implemented to an axisymmetric configuration of a cell to study the deformation and adhesion of its membrane. Another target of this work is to clarify the impacts of variety of material, binding and diffusion constitutive factors on membrane deformation and adhesion and to declare a rational comparison among them. / Graduate / 0548 / 0346 / golestan@uvic.ca

The mechanical behaviour of cells is essential in ensuring continued physiological function, and deficiencies therein can result in a variety of diseases. Also, altered mechanical response of cells can in certain cases be an indicator of a diseased state, and even actively promoting progression of pathology. In this thesis, methods to model cell and cytoskeletal mechanics are developed and analysed. In Paper A, a constitutive model for the response of transiently cross-linked actin networks is developed using a continuum framework. A strain energy function is proposed and modified in terms of chemically activated cross-links. In Paper B, a finite element framework was used to assess the influence of numerous geometrical and material parameters on the response of cross-linked actin networks, quantifying the influence of microstructural properties and cross-link compliance. Also, a micromechanically motivated constitutive model for cross-linked networks in a continuum framework was proposed. In Paper C, the discrete model is extended to include the stochastic nature of cross-links. The strain rate dependence observed in experiments is suggested to depend partly on this. In Paper D, the continuum model for cross-linked networks is extended to encompass more composite networks. Favourable comparisons to experiments indicate the interplay between phenomenological evolution laws to predict effects in biopolymer networks. In Paper E, experimental and computational techniques are used to assess influence of the actin cytoskeleton on the mechanical response of fibroblast cells. The influence of cell shape is assessed, and experimental and computational aspects of cell mechanics are discussed. In Paper F, the filament-based cytoskeletal model is extended with an active response to predict active force generation.  Importantly, experimentally observed stiffening of cells with applied stress is predicted. / <p>QC 20151209</p>

No description available.

The aim of this current research was two-fold; one aim was to develop a deeper understanding of job insecurity and its association with safety voicing. The perception of job insecurity was specifically examined in relation to job insecurity and its association with safety voice. The second aim was to examine safety voice with possible antecedents based on past research. This involved investigating the proposition that safety voice falls within a safety severity concern continuum. This continuum suggests that the severity of the safety concern may play a role in an employee’s willingness to voice these concerns. A questionnaire was devised to investigate perceptions of 47 employees from a single organisation. This organisation is undergoing a planned future job redundancy process (within a few years as of 2014). Correlational and univariate analyses were used to investigate any associations and differences in means between the different measures. Results from this research found partial support for the hypothesis that perceived organisational support, safety climate, and perceived co-worker support were positively associated with safety voice. The hypothesis that higher job insecurity would be associated with lower safety voice concerns was tested, and was not found not to be statistically significant to support the idea. This dissertation offers a preliminary indication that safety voice varies according to severity, and that job insecurity may affect employees’ likelihood to voice safety concerns. Practical implications and directions for further research are discussed.

No description available.

No description available.

Thesis (Ph. D.)--Missouri University of Science and Technology, 2008. / Vita. The entire thesis text is included in file. Title from title screen of thesis/dissertation PDF file (viewed May 9, 2008) Includes bibliographical references (p. 71-73).

Thesis (Ph. D.)--Oregon State University, 1993. / Typescript (photocopy). Includes bibliographical references (leaves 88-91). Also available on the World Wide Web.