Thesis (Ph. D.)--University of Chicago, Dept. of Biochemistry and Molecular Biology, December 2002. / Includes bibliographical references. Also available on the Internet.

Thesis (Ph. D.)--Universität Jena, 1911. / Vita. Includes bibliographical references (p. [37]-40).

Thesis (Ph. D.)--University of Missouri-Columbia, 2004. / Typescript. Vita. Includes bibliographical references (leaves 195-213). Also available on the Internet.

Thesis (Ph. D.)--University of Missouri-Columbia, 2004. / Typescript. Vita. Includes bibliographical references (leaves 195-213). Also available on the Internet.

The growth events which are responsible for the phototropic curvature of seedlings towards blue light were investigated by growth analysis of seedlings of Avena sativa L. Time-lapse video analysis of coleoptiles given equivalent unilateral or bilateral blue light stimuli showed that both the duration and fluence-rate of the light treatments affected the growth responses which were recorded. The results suggest that the growth responses in bilateral light occur simultaneously with the growth changes which cause phototropic curvature, although they do not appear to make any contribution to the magnitude of curvature. Seedlings were also subjected to continuous unilateral microbeam (1mm) irradiation of discrete zones, to investigate whether 'message' transmission occurs in phototropism. The growth changes which occur in response to this treatment were recorded over the whole length of a 20 mm seedling, but began at different times in different zones. It was concluded that there must be some kind of 'message' transmission following perception of a phototropic stimulus in Avena. The kinetics of the response showed that it was unlikely that transmission could be simply due to tissue light-piping from the position of the original light beam. Unilateral irradiation of a small zone at the base of a coleoptile resulted in negative curvature. This experiment provided some evidence for acropetal transmission of the phototropic signal. A study was also made on the effects of wounding on the growth of Avena seedlings. This led to a re-evaluation of the significance of the traumatropic response to unilateral wounding. The experiments showed that even a slight wound can have severe effects on the growth of a coleoptile. The results are discussed in relation to previous theories on the mechanism of traumatropic curvature.

Thesis (Ph. D.)--University of Missouri-Columbia, 2001. / Typescript. Vita. Includes bibliographical references (leaves 231-256). Also available on the Internet.

Thesis (Ph. D.)--University of Missouri-Columbia, 2001. / Typescript. Vita. Includes bibliographical references (leaves 231-256). Also available on the Internet.

Thesis (doctoral)--Université de Paris, 1958. / Includes bibliographical references (leaves 167-173).

No description available.

Waveguide architectures were inscribed within two different stimuli-responsive hydrogels capable of actuation. An electroactive hydrogel, which deforms when placed within an electric field, is demonstrated as a method for remote actuation and steering of light outputs. Lattices of waveguide with diameters on the microscale were embedded within hydrogel prisms, achieved through a nonlinear light propagation process known as self-trapping. This process is a result of balance between the natural divergence of light and self-focusing effects caused by an irreversible positive refractive index change during photopolymerization. Waveguiding structures are inscribed in the material because of this process. Square (2D) and near-cubic (3D) lattices were inscribed in hydrogel prisms, demonstrating the ability to remotely steer one or two light outputs simultaneously using an electric field. The overall optical effect is reminiscent of camouflaging techniques observed in marine creatures (ie. cephalopods). Additionally, a novel volumetric 3D printing technique previously demonstrated by the Saravanamuttu group was implemented to fabricate hydrogel cylinders capable of photothermal actuation. Coupling a thermoresponsive hydrogel material with a photoabsorber, areas irradiated by a light source are observed to contract. These contractions lead to the deflection of waveguiding cylinders towards the light source, reminiscent of the phototropic behaviours observed in particular plants (ie. sunflowers). The results of these studies provide insight for the fabrication of functional materials through nonlinear light propagation. Understanding these systems could provide knowledge for the fabrication of other stimuli-responsive materials with light-guiding properties. / Thesis / Master of Science (MSc)