1970-1979 Theses (MU)
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Item Birds of south central Canadian Habitat Islands : a biogeographic survey of distribution and abundance(University of Missouri--Columbia, 1979) Mulkey, Stephen S.; Faaborg, John R."As a concept and a biological unit of study, the island could be ranked with the cell as a prime mover in the biological sciences. Starting with the theory of evolution, islands have functioned as microcosms for the study of complex and wide-ranging phenomena. Within the last twenty years, renewed interest in islands has come about as the result of the elaboration of the theory of island biogeography (MacArthur and Wilson 1963, 1967). Inherent in the theory is the concept that principles determined in a smaller, biologically simplified unit could be analogously applied to more integrated systems. It is the goal of this study to test the hypotheses concerning oceanic and continental island faunas on a less isolated, more complex unit: the temperate mainland habitat island. In this study I define an habitat island as a discrete community of predominantly one ecosystem type surrounded by an area of habitat inhospitable to the members of such a community."--Introduction.Item Application of dynamic linear programming to an eight-year machinery selection model(University of Missouri--Columbia, 1970) Muchow, Jeffrey P.; Harshbarger, C. E."American agriculture has encountered a fascinating parade of change in recent years as characterized by the highly commercialized, specialized, and mechanized age sur rounding the agricultural community. Modern farm operators are participants in this dynamic environment and are faced with new challenges requiring skillful management techniques and expert decision capabilities. More specifically, the task involves a continual examination of resource efficiency and prudent planning of the overall farm business organization. Complex decisions of such magnitude are demanded of a technologically changing industry. The increasing mechanization in modern agriculture, while undoubtedly easing some physical tasks, does little to simplify management problems. Economic analysis of management problems associated with mechanization has traditionally been static in nature, thus ignoring the problems encountered with the time variable in our dynamic environment. Introduction of the time element can have an enormous impact upon the solution of these problems relative to the timing of decisions made over a planning horizon. Farm managers are interested in an organization of enterprises which maximizes income over a series of years. A decision implemented in one year is dependent upon the availability of resources, and its impact may determine the allocation of resources and ultimate farm plans which are feasible in future years. Hence, static analysis can only compare the optimality of situations occurring in two different time periods. Unfortunately, the procedure is unable to analyze or specify the economic decisions incurred during the interim time period. Application of dynamic models to management problems associated with increasing mechanization in a commercial type of agri culture can incorporate time as a decision variable and concentrate on maximizing a stream of income over time for the farm operator."-Introduction.Item Parathyroid function in the box turtle, Terrapene carolina triunguis(University of Missouri--Columbia, 1973) Magliola, Lawrence; Breitenbach, Robert P."A fundamental component of the concept of homeostasis is that the functional integrity of a cell is dependent upon maintaining the relative constancy of its internal environment. Since all cell membranes are more or less permeable to a variety of organic and inorganic constituents, the cells are, not surprisingly, closely dependent upon the properties of the solution which surrounds them. Two of these properties, the relative and the absolute concentration of ions in solution, are of special significance in mineral metabolism. Seen from the perspective of evolution, extracellular mineral regulation was achieved by a modification and amplification of more primitive processes involved in intracellular homeostasis."--Introduction.Item Isolation of resistant mutants of Escherichia coli to the photodynamic action of various dyes(University of Missouri--Columbia, 1971) Hafner, Jerry Lynn"Photodynamic action is the action on cells or photooxidation of molecules by visible light in which a photosensitizer and oxygen are necessary. The photosensitizer is commonly a dye. The basic principle behind photodynamic action is energy transfer. Energy from light is transferred to a sensitizer, causing a shift of an electron to an energy level higher than normal. This energy is then transferred to a susceptible biological material causing a disruption of its structure or function. This activity differs from a simple chemical reaction in that the sensitizer alone will have no effect on the biological system; the activity is light dependent. Similarly, it is not simply a radiation action because the light in itself is not detrimental as would be ultraviolet or X-radiation. The studies reported here deal with the ability of a number of different dyes to act as photosensitizers. To determine effect, the growth rate of the organism, when placed in a particular dye plus light and air, was compared to the growth rate with no dye present. Further, if a dye was an effective photosensitizer and caused a decrease in growth rate, then it may be possible to isolate a mutant strain resistant to the photodynamic action of the dye. Isolation of such mutants was attempted for those dyes which were photosensitizers. Mutants which are resistant to ultra-violet radiation have been useful in studies of the mechanisms of action of the light and also investigations on repair of UV damage. Photodynamic resistant mutants may have a corresponding use in the study of photodynamic action."--Introduction.Item An economic analysis of urban migrant diets in northeast Brazil(University of Missouri--Columbia, 1977) Amoni, David; Blase, MelvinNutrition has traditionally been considered a residual of economic development rather than an integral component. Direct nutritional policies have, at best, been discounted while in some countries they are conspicious by their absence. Many countries have concentrated on intensive capital investments for industrialization and agricultural development. This has created an internal dichotomy resulting from disequilibrated economic development and welfare distribution. While recent development efforts have been increasingly devoted toward those bypassed by the development process, e.g., the small farmer, many developing countries continue dualistic economic characteristics.