Thesis (Ph. D.)--Ohio state university, 1919. / "Published as no. 126 Psychological monographs, Princeton, N.J."

Thesis (Ph. D.)--University of Wisconsin--Madison, 1982. / Typescript. Vita. Includes bibliographical references (leaves 144-150).

Thesis--Wisconsin. / Vita. Includes bibliographical references (leaves 71-75).

Thesis (M.S.)--University of Wisconsin--Madison, 1973. / eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1980. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 161-165).

Thesis--University of Michigan. / Includes bibliographical references.

The overall objective of the work described in this Dissertation was to develop and verify a general reaction and diffusion model for non-catalytic reactions between gases and porous solids, particularly those relevant to the clean use of fossil fuels. Here, the internal pore structure of the solid was characterised by observing the kinetics in a regime limited only by intrinsic chemical reaction. It was hypothesised that a simple arbitrary function, f(X), determined from experimental measurements of rate vs. conversion in a kinetically-controlled regime, could be used in place of formal, mathematical pore models, to describe the evolution of pore structure during a reaction influenced by intraparticle mass transfer. The approach was used to study (i) the gasification of chars by CO2, where the only product was gaseous, (ii) the calcination of CaCO3 cycled between calcined and carbonated states, where the products were a gas and a solid, and (iii) the sulphation of virgin and sintered CaO by SO2, the only product being solid. Studies of calcination showed that, at least for limestones subjected to a history of cycling between the calcined and carbonated states, a correctly-determined f(X) could be applied to different sizes of particles at temperatures different to that at which f(X) was determined. Somewhat surprisingly, it was found that the f(X) determined from one, cycled, limestone was successful in predicting the conversion of other cycled limestones of different geological origin. It was concluded that the process of cycling between the calcined and carbonated states at the same process condition had significantly reduced the differences apparent in the pore structures of the different limestones when first calcined from the virgin materials. The experimentally-observed effects of pressure, concentration of CO2 and temperature described in the literature were explained successfully by the mathematical model. Finally, the study of sulphation explained satisfactorily (i) the reason for there being a maximum in the ultimate conversion of CaO to CaSO4 at a specific temperature, and (ii) the processes controlling the overall uptake of SO2 by sintered CaO, such as might be produced from a calcium-looping cycle for capturing CO2 from flue gases. For both the virgin and the cycled calcines, the ultimate conversion to CaSO4 seemed to be limited by the pore volume below 300 nm diameter. Two mechanisms were identified to explain why CaO cannot be fully sulphated to CaSO4. In summary, this work has demonstrated the applicability of the general reaction and diffusion model to gasification, calcination and sulphation reactions, and verified the f(X) approach for describing pore evolution during reaction.

5 normal subjects randomly selected from the entire grade 8 male population at Vancouver Technical Secondary School, and 5 retarded subjects from the special class at the same school were exposed to a series of 5 reaction time experiments involving a button press response to a series of stimulus lights, and varying in complexity from simple reaction time to an 8 choice situation. The object was to test the effect of the decision mechanism involvement on reaction time. It was hypothesized that the retardates would be significantly slower than the normals on the reaction time tasks, and that a linear equation would describe the best fitting line of the normals when the speed of response was plotted against the informational load of the stimulus, while a non-linear equation would best describe the retardates' scores. The result indicated that there was no significant difference between the mean values of the reaction time scores of the retarded and the normal groups, but a probability level of .075 was obtained. There was no statistically significant evidence to indicate which equation was the best fit to the retarded and normal scores; however, visual inspection indicated that the observed trends were in agreement with the prediction. It was concluded that although the evidence presented was not statistically significant, enough evidence has been presented to suggest that retardates do not react to a level of information beyond 2 bits in a linear fashion that typifies the normals, and that further research is required to ascertain the causal factor in the retardates' inability to react at a normal level on a reaction time task. / Arts, Faculty of / Psychology, Department of / Graduate

The dispersal behaviour of apterous pea aphids, Acyrthosipon pi sum (Harris) was studied in the laboratory and field. In the laboratory, aphids exhibited two types of behaviour while on the ground, after dropping from plants in response to predators. Most aphids showed a high frequency of turning and tended to return to the plant they left, while a smaller proportion walked in straight lines and did not return to the plant they left. Adults and older nymphs had the highest proportion of individuals which showed the second type of behaviour and adults showed the greatest tendency to disperse to plants more distant than the nearest available plants. Young instar aphids were less successful at locating a host than older nymphs and adults. Aphids were placed on the central bean seedlings within plots, inside large field cages. Adult coccinellids were released into two of the cages while the other cage remained predator-free. Aphids in the cages with predators frequently moved between plants, while aphids in the predator-free cage did not. Adult aphids colonized more plants and had a lower mortality while on the ground than all other instars. Aphids did not show a preferred dispersal direction and the distance dispersed by aphid nymphs was proportional to the density of aphids on the plant they left. The importance of emigrating apterae in the exploitation of new resources and the regulation of aphid populations is discussed. Bean plants infected with an aphid transmitted virus were transplanted into the central position of bean plots in the field cages. Aphids were placed on the central infected plants and adult coccinellids were released into two of the three cages for three days. Aphids frequently moved to other plants from the centre infected plant in the two cages with predators but not in the predator-free cage. When plants were examined two weeks later, significantly more plants were infected with virus in the cages with predators than in the predator-free cage. New virus infections were correlated with plants that were visited or colonized by aphids from the central infected plant. The influence of predators in the spread of aphid transmitted diseases is discussed. In laboratory experiments, pea aphids from Vancouver were presented with alarm pheromone from irritated conspecifics. Adult and fourth instar aphids responded to the pheromone by either dropping, running or backing up. Instars one, two and three responded to the pheromone only when a vibratory stimulus accompanied it. A high proportion of all instars responded to the double stimulus by dropping. When adult aphids from Vancouver and Kamloops were presented with alarm pheromone, the Kamloops adults exhibited a more conservative reaction to alarm pheromone. Kamloops adults also were more conservative about leaving their plant when confronted by a coccinellid predator. A hypothesis is presented, which accounts for the differences in escape reactions between instars and biotypes. The hypothesis takes into consideration predation risk, escape behaviour repertoire and survival on the ground. Pea aphid adults resisted heat paralysis longer than first instars when subjected to high temperature treatments. All aphids succumbed to paralysis sooner at 42°C than at 37.5°C, but there appeared to be no difference in aphid survival in dry compared to moist conditions at high temperatures. Kamloops aphids were not more resistant to high temperatures. / Land and Food Systems, Faculty of / Graduate

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