The facial pits characterizing the snake subfamily Crotalinae have been demonstrated to be important as thermoreceptors in detecting the presence of prey animals and in directing the stroke towards them. So specialized a receptor as the pit organ, if it is to survive, must be functionally effective. If this organ is important in locating prey under natural conditions it would be expected that if these pits were destroyed this importance would be reflected in growth rates, weight changes,, or survival. In twenty of forty snakes collected in the spring of 1963 the pits were destroyed by electric cautery. After weighing, measuring, and marking, the snakes were released at the point of capture. The growth of the recaptured cauterized and non-cauterized snakes was compared. In addition, controlled tests were made with the recaptured snakes, using live mice and light-proof boxes to determine the effectiveness of cautery. A significant statistical difference was found in the growth rates of the females, the cauterized snakes growing more slowly. No difference was found in the growth rates of the males. However, the controlled tests indicates the pits to be important to the males as well as to the females. Weight changes were too variable to reveal differences between normal and cauterized snakes and no difference in survival was evident between the two treatments. To overcome the effect of individual variation in growth rate further study is required of larger samples over a longer time period. / Science, Faculty of / Zoology, Department of / Graduate

This study examines the spatial evolution of the Eastern Pacific halibut fishery over the period 1888-1972 in terms of resource exploitation and vessel-port interaction and attempts to delineate the factors which brought about the observed patterns. Four distinct stages of development are identified: (1) a stage of spatial confinement and resource depletion characterized by corporate involvement and restricted vessel range, (2) a stage of spatial extension, company fleet decline, and independent fleet expansion, (3) a stage of spatial adjustment, quota control, and extreme competition, (4) a stage of further spatial extension, fleet decline, and maximum sustained yields. The spatial structure of the industry at each stage of development is shown to be a function of resource availability, fishing costs, and changes in halibut fleet behavior. The time-cost-distance factor between producing grounds and the landing/processing sector of the industry proved to be a critical factor in a fishery that was characterized by increased competition for annual quotas. Conceptual models of the industry's spatial structure have been developed to portray the major changes which occurred from one stage to the next. These in turn are further developed to conceptualize the evolution of the halibut fishery over the 1888-1972 period. / Arts, Faculty of / Geography, Department of / Graduate

The major purpose of this study was to examine the physiological basis of the differences in the early life histories of pink Oncorhynchus gorbuscha, chum O. keta, coho O. kisutch, chinook O. tshawytscha and sockeye O. nerka. To this end, the following working hypotheses were tested: (i) the embryo, alevin and fry of pink and chum salmon are euryhaline, whereas the same life stages of coho, chinook and sockeye are stenohaline and (ii) the euryhalinity of pink and chum is due not to high tissue tolerance but to their ability to regulate the osmotic and ionic concentrations in their blood, whereas the stenohalinity of coho, chinook and sockeye stems from their inability to osmoregulate and ion regulate. The results did not completely support these hypotheses. The LD₅₀ values and the osmoregulatory data obtained from embryos indicated that pink and chum are not euryhaline as hypothesized but like coho, chinook and sockeye embryos are stenohaline. However, pink and chum embryos showed significantly greater salinity resistance and osmoregulatory ability than embryos of the other species. The data obtained from alevins also did not support the working hypothesis for alevins of all five species were found to be stenohaline. But, as in the case for embryos, pink and chum alevins showed greater salinity resistance and osmoregulatory abilities than coho and sockeye alevins. This ability of pink and chum was correlated with better ionic regulation of sodium and chloride. Although chinook alevins survived considerably longer in 31.8 °/oo sea water than coho and sockeye alevins , their ability to osmoregulate and ion regulatewas not very different from that of coho and sockeye alevins. It was concluded, therefore, that the greater salinity resistance of chinook alevins was due to high tissue tolerance. Contrary to the results with embryos and alevins, the data obtained from fry supported the working hypotheses. The results showed that pink and chum were euryhaline and that this condition was due to their ability to osmoregulate and control the levels of sodium and chloride in the blood. Coho, chinook and sockeye fry were found to be stenohaline and were unable to regulate the osmotic and ionic concentrations in their blood. As in the case of alevins, chinook fry, due to higher tissue tolerance, manifested greater salinity resistance than coho and sockeye. When the data for all species of embryos and fry were grouped and compared to the alevins taken as a group, the LD₅₀ values of embryos and fry were found to be significantly greater than those of the alevins . The blood osmotic concentrations of embryos and fry exposed for the same duration in 31.8 °/oo sea water were significantly lower than the blood osmotic concentrations for alevins. It was included, therefore, that embryos and fry have greater salinity resistance than alevins because of the greater osmoregulatory ability of embryos and fry. On the basis of these results as well as information obtained from the literature, speculations were made on the phylogenetic relations within the genus Oncorhynchus. / Science, Faculty of / Zoology, Department of / Graduate

Triploidy was induced in rainbow trout, Salmo gairdneri Richardson, by heat shock (10 min at 26, 28 or 30°C, applied 1 min after fertilization at 10°C) and in pink salmon, Oncorhynchus gorbuscha Walbaum, and coho salmon, 0. kisutch Walb., by hydrostatic pressure shock (1, 2, 3 or 4 min at 69,000 kPa, applied 15 min after fertilization at 10.5°C). Triploid individuals were identified by the flow cytometric measurement of DNA content of erythrocytes stained with propidium iodide. Gonadosomatic index was reduced to a much greater extent in triploid females than males. Triploid ovaries remained very small, and contained virtually no oocytes. Triploid testes became quite large, but few cells developed beyond the spermatocyte stage. Triploid male rainbow trout had significantly lower spermatocrits than diploids, and their spermatozoa were aneuploid. Growth rates were the same for diploid and triploid rainbow trout, but triploid female pink salmon were smaller than maturing diploid females and diploid and triploid males of the same age. Triploid males of both species developed typical secondary sexual characteristics and had normal endocrine profiles for plasma sex steroids and plasma and pituitary gonadotropin, but their cycle was delayed by about one month. Triploid females developed no secondary sexual characteristics and showed no endocrine signs of maturation, even at the level of the pituitary. Vitellogenin synthesis was induced in immature diploid and triploid coho salmon by the weekly injection of 17β-estradiol. Plasma vitellogenin and pituitary gonadotropin levels were significantly elevated over levels of sham-injected fish, whereas plasma gonadotropin levels were slightly depressed. There was no significant difference between diploids and triploids for any of these results, indicating that normal vitellogenesis is not impaired by triploidy per se. It is concluded that triploids of both sexes are genetically sterile, but that only triploid females do not undergo physiological maturation. Triploid testes develop sufficiently for their steroidogenic cells to become active, which is not the case for triploid ovaries. The occasional cells that pass through the normal meiotic block develop to full maturity in triploid males but not in triploid females, probably due to the absence of the appropriate stimulus to initiate and maintain vitellogenesis. Although triploids of both sexes should make valuable tools for basic research on reproductive physiology, only the females will be useful for practical fish culture to avoid the economically detrimental effects of maturation in fish destined for human consumption. / Science, Faculty of / Zoology, Department of / Graduate

The purpose of this study is to examine the role and locations of “magnetic centers” which evolve, or are established , form the flow of information and the lines of authority on a university campus. It is believed that the certain individuals are centers of information, “magnetic centers,” and they draw messages from other individuals at all levels in the communications network of the structure of structures of an institution. By doing this they exert influence through a filtering process of the flow of information they receive and disseminate. These magnetic connectors may or may not be recognized by other individuals within the organization. Based on the assumption that there are certain individuals who could be classified as magnetic centers the following questions were considered: (1) Are there magnetic centers in the structure or structures of a university?; (2) Are these individuals magnetic centers established because of their position or because of other characteristics held in common?; (3) Are the centers permanent in the structure? If there is more than one structure, which structure appears to be more permanent?; (4) Which structure dominates in the number of recognized magnetic centers?; (5) Do the recognized magnetic centers have common procedures for getting information?; (6) Are there magnetic centers which are not recognized by other individuals in the structure or structures? Are there ascertainable reasons for their non-recognition?

No / An analysis of the geopolitics of Mongolia between the Great Powers of the Asia-Pacific.

A computer simulated model representing carbon dynamics within the eastern equatorial Pacific was developed. The three compartment model incorporated the physical, biological and chemical processes most significant to the region of study representing both "normal" and highly disruptive conditions. The events which interrupt the normal carbon dynamics are known as El Niño events. The most profound effects that the El Niño has on the eastern equatorial Pacific are anomalously high sea-surface temperatures and a weakening in the typically intense upwelling motion. It is during these periods that the equatorial Pacific has been thought as being a sink for carbon dioxide. The EPCM incorporated these extreme changes, as typified by sea-surface temperature and upwelling, in order to determine the levels of sensitivity of the model parameters to these adversive conditions. The EPCM suggests that variations in upwelling rates have a much greater effect on model parameters than a change in sea-surface temperatures. As well, it has been suggested that cooler temperatures limit zooplankton and phytoplankton parameters much more than warmer conditions. Lastly, it has been demonstrated that, according to the EPCM, the equatorial Pacific is always a source of carbon dioxide to the atmosphere. Net movement towards the atmosphere persists even during periods when upwelling is at its weakest, as simulated by the EPCM. / Thesis / Bachelor of Science (BSc)

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Earth and Planetary Sciences, 1981. / Microfiche copy available in Archives and Science / Vita. / Includes bibliographies. / by John Crowe. / Ph.D.

This thesis aims to address how the strategic partnership between Russia and China is affected by the absence of the Intermediate-Range Nuclear Forces Treaty, also known as the I.N.F. Treaty. Through historical evidence of the strategic partnership, along with various balancing theories, this thesis presents the argument that American abrogation of the I.N.F. Treaty would result in strengthened relations between Russia and China if the United States deploys intermediate-range nuclear weapons to the Pacific. Without U.S. deployment, however, the Russian-Sino strategic partnership will likely remain undisturbed. / Master of Arts / The purpose of this thesis is to examine the strategic partnership between Russia and China in the absence of the Intermediate-Range Nuclear Forces Treaty, also known as the I.N.F. Treaty. This thesis presents the argument that American abrogation of the I.N.F. Treaty would result in strengthened relations between Russia and China if the United States deploys intermediate-range nuclear weapons to the Pacific. Without U.S. deployment, however, the Russian-Sino strategic partnership will likely remain undisturbed.

In recent years we have seen increasing debate over the allocation of PNW water resources. In particular there are conflicts over using the river system for irrigation vs. electricity production. Denying the hydroelectric system water implies higher costs to electricity consumers as producers substitute more expensive nonhydro resources. This research looked at the impact of new irrigation on PNW electricity consumers. This was done under varying assumptions of demand response and farmer payments for pumping of irrigation water. The study also examined the difference between the current policy of allowing farmers to take all the water they need, and a policy in which withdrawals are limited in periods of low streamflow. Simulations were run to determine the amount of electricity production lost because of withdrawals. These results were then used in a series of simulations to estimate the economic impacts under the various assumptions and policies. It was found that irrigation caused losses to electricity consumers. In some cases this loss was on the order of $200/acre of irrigated land. The loss was significantly mitigated under the interruptible policy. Farmer payments for irrigation energy also reduced the loss to consumers. / Graduation date: 1985