This thesis presents theoretical and experimental investigations of atmospheric refraction and diffraction of sound over curved surfaces. The main contributions of this work are as follows: The development of an alternative method for calculating the influence of wind on sound propagation in the presence of a ground of finite impedance. The development of numerical models to calculate sound propagation due to monopole and dipole sources over cylindrical or spherical convex and concave surfaces of finite impedance. Laboratory measurements of sound propagation over curved surfaces and comparisons with the proposed theoretical and numerical models. The exploration of the theory for surface wave contributions in an upward refracting atmosphere in the light of obtained experimental data and observation of the surface waves above a convex surface. Experimental and theoretical investigations of the effectiveness of a barrier in the presence of sound speed gradients.

No description available.

This thesis reports a study of the flowering response of heather, <i>Calluna vulgaris</i> (L.) Hull and of experimental procedures designed to modify the time of onset of that process, with particular reference to year-round production of the flowering plant, in line with recent expansion in the European and British pot plant industries. Microscopic apical examinations were employed throughout to identify and monitor development of floral primordia. Research concentrated on flowering responses to photoperiodic stimuli, provided by various lighting regimes, including fluorescent and tungsten sources, differing in spectral composition and irradiance intensities. <i>Calluna</i> clearly required long day lighting for both floral initiation and development. This response was shown to be influenced by temperature conditions, with higher temperatures promoting flowering. Various changing-temperature regimes were also investigated. Reduced-temperature storage of plants with floral buds was successfully employed as a method of delaying flowering time. Influences of cultivar and seasonal flowering type were also investigated. Results indicated that seasonal flowering sequences were maintained under artificial lighting conditions; so that later flowering types required longer periods of lighting. Evidence suggested a cultivar-dependent sensitivity to irradiance intensity. This information was incorporated in an evaluation of costs incurred during photoperiodic induction, and from this an economic protocol for production of flowering <i>Calluna</i> was compiled; commercial viability being an integral part of the overall study. The minimum plant size capable of floral induction was investigated and related to different modes of propagation; in both macro- and micro-propagated plants flowering occurred soon after root development. Seedlings, however, had to pass through a juvenile phase. The limited micropropagation study revealed that adventitious shoot production involved transitory tissue rejuvenation.

No description available.

Adventitious rooting in stem cuttings of Eucalyptus grandis Hill ex Maid. was thought to be influenced by a putative inhibitor. In previous studies it has been usual to infer the presence of putative rooting inhibitors and promoters from the mung bean bioassay, but the possibility was raised that treatment responses in this assay could be mediated more by the concentration of the treatment solution than by the chemical identity of the solute. This appeared to be so: several solutes, including hydrochloric acid and common salt, were found to promote the rooting of mung bean cuttings when present in the treatment solution at an apparently injurous concentration. The concept of promoters and inhibitors of adventitious rooting, as constituted at present, was considered to be an unfavourable approach for further studies. Stem cuttings must contain a morphogen, broadly defined, which operates the 'switch' from stem to adventitious root. The leaves and buds of E.grandis stem cuttings did not appear to be sole sources of a morphogen (as is often assumed), but nevertheless the activity of the leaves and buds was good for rooting. This activity was reflected in the pattern of root emergence. A slight preponderance emerged from the leaf trace sectors of the stem, suggesting that the leaves and buds cause a morphogen (of unknown origin) to circulate in the cutting. The existence of a vascular morphogen was confirmed and it proved to be very mobile in the stem, suggesting that it is well distributed circumferentially at the base of the cutting rather than confined to the leaf trace sectors. It appeared to be super-abundant at the base of easy-to-root cuttings, but it was not possible to tell to what extent the morphogen was rendered accessible to the sites where roots initiate. In general, the rate of efflux from the transporting tissues, the rate of attenuation of the morphogen after efflux, and the number of potential sites for root initiation must interact on a small scale to determine rooting ability. The relative prominence of these groups of factors would be expected to vary with circumstances, for example at different locations within a single stem cutting, so the traditional concept of a limiting morphogen ('rhizocaline') is unhelpful in its simplest form. Nevertheless, the rhizocaline concept provides a starting point towards a more comprehensive view of adventitious rooting, which is required in order to predict and improve rooting ability. This view remains a remote objective because many of the factors which could be important have recieved very little attention and will be difficult to elucidate. / Thesis (Ph.D.)-University of Natal, Pietermaritzburg, 1988.

Thesis (Ph. D.)--Ohio University, March, 1982. / Title from PDF t.p.

Thesis (M.S.)--Ohio University, March, 1980. / Title from PDF t.p.

Dissertation (Ph.D.)--Auburn University, 2006. / Abstract. Vita. Includes bibliographic references.

Thesis (Ph. D.)--University of California, (Davis), 1952. / Degree granted in Plant Pathology. Includes bibliographical references (leaves 69-71). Also available via the World Wide Web. (Restricted to UC campuses).

Thesis (M.S.)--University of Wisconsin--Madison, 1965. / Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 44-48).