A phase-space asymptotic approach to wave propagation in homogeneous dispersive and dissipative media is discussed which has several advantages by comparison to conventional techniques, such as the stationary phase method, ordinary ray tracing, etc. This approach, which is based on the wave-kinetic theory [1,2], is used to examine in detail three types of one-dimensional canonic dispersive and dissipative media: cubic dispersive and quadratic dissipative, cubic dispersive and quartic dissipative, quintic dispersive and quartic dissipative. Purely dissipative media are also investigated. The analysis is also carried out using standard Fourier techniques for comparison purposes. For an arbitrary medium, exact solutions are impossible. Approximations must be made which give rise to new basic functions defined in integral form. The method of steepest descents [3], the WKB method [4], the method of dominant balance [4] and the FORMAC73 language [5] are utilized to find asymptotic series for these functions. / M.S.

The synthesis of ion containing copolymers by emulsion copolymerization of polar vinyl monomers with ionic vinyl monomers has been studied. The copolymerization of n-butyl acrylate with sodium-pstyrene sulfonate proved to be particularly rapid. With the proper choice of chain transfer agent soluble polymers with enhanced rubbery plateaus have been synthesized. The best conditions for the polymerizations were a reaction temperature of 70°C and reaction times up to 8 hours with TWEEN 20 used as the emulsifier. Analysis of the copolymer composition by UV spectroscopy, and potentionmetric titration was not possible due to the vastly different solubility characteristics of the components of this system. This prevented the use of homopolymer blends as standards for these techniques. The study of the copolymerization kinetics of this system was very difficult due to the coagulation of the polymer latex. The rate of copolymerization was nevertheless shown to be very rapid. The synthesis of the sulfonated styrene monomer by a literature procedure led to the formation of a covalent sulfonamide instead of the desired ionic sulfonate. This product was substantiated by l_H and 13_C NMR infrared, mass spectral, and melting point data. Study of the physical properties of these polymers by differential scanning calorimetry and thermal mechanical analysis showed them to have only a low temperature acrylate glass transition with an enhanced rubbery plateau due to the ionic pseudo crosslinking. Stress-strain measurements showed that this pseudo crosslinking gives enhanced tensile properties (modulus, tensile strength) in the ion-containing polymers. / M.S.

Vertical and lateral contrast in thermal conductivity produce refracted isotherms and anomalies in heat flow. For simple steady-state heat conduction, three models of rift basins with various fault attitudes (vertical, high-angle, and listric) and a thermal conductivity ratio of 1:2, basin material:country rock, are analyzed numerically using the computer program CCC which utilizes the Integrated Finite Difference Method. The isotherms are refracted near the contrast in thermal conductivity and heat flow anomalies are present on both sides of the fault. An analytical solution for the temperature distribution across a vertical fault is found by representing the contact as two plates in perfect thermal contact and solving Laplace's equation in two dimensions. The normalized heat flow is calculated for the models and is also approximated by an empirically derived equation. The equation for normalized heat flow can be derived from the analytical solution to Laplace’s equation. From the analytical solution for the temperature distribution, the maximum and minimum heat flow near a thermal conductivity contrast is determined from the average thermal gradient and the conductivities of the rocks. The analytical solution also yields an equation which when solved iteratively can be used to estimate the distance to the fault. The analytical and numerical results shows excellent agreement. A linear equation which represents the horizontal normalized heat flow distribution is empirically derived. This equation is based on the distance from the fault, the minimum heat flow in the basin and the horizontal change in normalized heat flow. The minimum normalized heat flow for listric faulting is found to lower in value than for the vertical and high-angle fault models. If a heat flow determination is lower than the calculated minimum heat flow, the fault attitude is different from vertical. The linear equation for heat flow is simple enough for field use. Thermal equilibrium data can supplement interpretation of structure as deduced from other geological and geophysical data sets. / M.S.

Several photosynthetic inhibitors were screened for relative photosynthetic reduction on leaves of greenhouse-grown peach trees. The most effective were 8% Vapor Gard, 10M diurcn, 10⁻³M ABA, and 10⁻³M terbacil, all of which reduced net photosynthesis (Pn) rates by 50% or more by 1 day after treatment without causing excessive phytotoxicity. Of these 4 treatments, terbacil at 10⁻³M gave the most consistent effects; treated leaves re-established near normal Pn rates within a week of treatment. At 1, 3, and 7 days after treatment with terbacil at 10⁻³M, Pn rates were 1.1, 9.0, and 16.6 mgCO₂ dm⁻² hr⁻¹ , respectively, compared with a pretreatment rate of 19.7. Terbacil was applied as limb treatments to bearing peach trees in the field to determine fruit thinning activity. Treatments were: single applications of 1000 or 2000 ppm, double applications a week apart of 1000 ppm, or 2000 followed by 1000 ppm. All treatments significantly reduced fruit number. Fruit drop was 73 to 90% on treated limbs compared to 20% on non-thinned check limbs. Only the single 1000 ppm treatment resulted in fruit size similar to the hand-thinned check, however, all treatments increased fruit size over the non-thinned checks. / M.S.

A series of experiments was conducted to determine the effect of light, auxin, carbohydrate levels, mineral nutrients and rooting on the net photosynthetic (Pn) rate of unrooted Ilex crenata Thunb. 'Helleri' cuttings. Optimal photosynthetic activity occurred at PAR levels of about 600 micro-Einsteins m⁻² sec⁻¹. The emergence of roots increased the Pn rate. High plant carbohydrate levels were correlated to lower Pn rates while higher Pn rates were correlated to lower CHO levels. These relationships may be indicative of source-sink interactions on the Pn rate of Helleri holly cuttings. An exogenous basal application of indolebutyric acid (IBA) contributed to an increase in cutting Pn, as was the case with the addition of mineral nutrients. / M.S.

Ultrasonic transducers with concentric annular ring electrodes can be used to generate various circularly symmetric acoustic field profiles. These transducers can also electronically simulate a circular phased array and generate a focused ultrasonic beam. A model which predicts the acoustic transducer output for a given scaled voltage input has been developed. Several transducers have been designed using this model. Special attention has been given to the unique case of the two-dimensional radially Gaussian amplitude profile. Fabrication techniques for these transducers have been developed and are discussed. A microprocessor-based data acquisition system is described which will characterize the two-dimensional transducer profile as well as the propagation profile along one radial axis. Example tests of some of these transducers are presented. / M.S.

Maintenance of pregnancy in the ewe depends on progesterone synthesized by the ovaries during the first third of gestation and by the placenta during the last two-thirds of gestation. There have been few investigations of in vitro synthesis of progesterone by the ovine placenta or of mechanisms controlling placental steroidogenesis. Weekly blood samples were collected from ten gestating ewes that were sacrificed for collection of placental tissue on either day 80 (n=5) or day 115 (n=5) of gestation. All blood samples were analyzed for progesterone by radioimmunoassay. Immediately after each ewe was sacrificed, cotyledons were collected from different areas of each placenta, minced, and incubated in 2 ml of culture medium for either .5, 1, or 2 h. Minced tissue (100 mg) was incubated either in the presence or absence of pregnenolone and the tissue was subject to addition of either human Chorionic Gonadotropin (hCG), 3’, 5', cyclic adenosine monophosphate (cAMP), luteinizing hormone-releasing hormone (LHRH) or no additional treatment. Progesterone concentration in the medium after incubation were determined by radioimmunoassay. The temporal pattern of in vivo progesterone synthesized during gestation exhibited a biphasic increase with elevations occurring between days 70 and 80, and 95 and 115 of gestation. The difference in progesterone concentration in incubation medium after incubation of placental tissue collected on day 80 or day 115 of gestation was similar in magnitude to the difference in plasma progesterone concentrations of samples collected on those days. At day 80 and 115 of gestation, in vitro progesterone concentrations were 8.4 and 15.3 ng/ml, respectively, while in vivo progesterone concentrations at day 80 and 115 were 7.2 and 12.5 ng/ml, respectively. Progesterone accumulation in the medium of placental tissue collected at 115 days of gestation was greater than concentrations of progesterone in tissue collected at 80 days of gestation (P<.01). HCG had no effect on progesterone accumulation in the incubation medium; however, cAMP and LHRH significantly affected progesterone concentrations when pregnenolone was added to the medium of tissue collected on day 115. Cyclic AMP significantly increased progesterone concentrations in the medium after 2 h of incubation over that of tissue incubated alone (354.1 vs 402.6 ng/g). Mean progesterone concentrations in the medium of tissue incubated with LHRH were lower than control incubations after 1 h (288.8 vs 355.6 ng/g) and 2 h (306.1 vs 354.1 ng/g) of incubation. / M.S.

A constant-strain wear test apparatus was built and used to test polyethyleneterephthalate. The results of the constant-strain wear tests were compared to results from a constant-strain fatigue test. The results of the wear test showed that the polymer did not fatigue below the surface where the distortion energy was calculated to be a maximum. Instead, the polymer fatigued in an interfacial region at the surface due to stress concentrations resulting from surface irregularities, inhomogeneities, and localized adhesive forces. The adhesive forces were seen to increase as the number of cycles of the test increased eventually becoming the dominant frictional force. / M.S.

Ph. D.

Ovipositors of female leafminers were examined microscopically to locate and describe types of sensory receptors present. Two basic types were found: trichoid sensilla and basiconic sensilla. These receptors are believed to function as mechano- and chemoreceptors to evaluate the suitability of a host plant for feeding, oviposition, and subsequent larval development. Two greenhouse experiments were conducted to evaluate the effects of photoperiod and application of plant growth regulators on two factors: 1) feeding and oviposition site selection and 2) spatial distribution of feeding and oviposition sites on individual chrysanthemum plants. In the photoperiod experiment, leafminers fed and oviposited more intensely on chrysanthemums grown under short days (SD) than on plants grown under long days (LD). Densities of feeding punctures and larval mines on chrysanthemums grown under SD was positively related to leaf height on the plant, and negatively related to leaf trichome density. Spatial distribution of feeding and oviposition sites within plants under LD was variable, and no specific pattern of preference was discerned. An experiment to determine the effect of plant growth regulators on site selection by female leafminers revealed no significant differences (P > 0.05) in feeding and oviposition densities on chrysanthemums treated with plant growth regulators napthalene napthaleneacetic acid, gibberellic acid, and daminozide. / Master of Science