M. S.

No description available.

No description available.

1. The inheritance mechanism or resistance to lindane in the German cockroach, Blattella germanica (L.) was studied by determining the toxicity of lindane to the following populations ot cockroaches: a) lindane.resistant and non-resistant strains, b) the F1 and F2 progeny of reciprocal crosses between the two parental strains, c) the F1 and F2 progeny of backcrosses between the reciprocal cross F1 males. and resistant and non-resistant strain females, d) the progeny of pair matings within resistant and non-resistant strains and e) eight successive generation of a resistant strain isolated from further insecticide selection. 2. The method. employed in rearing the cockroaches and obtaining toxicological data on the different populations, as well as the genetical and statistical procedures, are described. 3. The toxicological data tor the mass matings are presented 1n the form of regression lines fitted by appropriate statistical analyses. 4. The toxicological data. for the pair matings, transformed into "indices of resistance," are presented in tabular form. 5.. Appropriate conclusions are drawn from the data to explain the inheritance mechanism of lindane resistance in the German cockroach. / Ph. D.

Present data are insufficient to permit final recommendations as to the best winter-green crop for geese of the sight crops studied. Italian rye grass appears, however, to have very good possibilities because of its good production of forage, its utilization and apparent high preference by geese coupled with a low preference by deer. It is also a relatively inexpensive field crop. Ladino clover is good as a second year crop for both geese and deer besides being economical to plant and maintain, but should be planted early to permit satisfactory first year utilization. Oats, on the refuges on which this investigation was conducted, appears a poor choice because of its high preference by deer and low goose preference. There is a need for additional investigation to permit the accumulation of more conclusive data. Presently reported results reflect limitations which might be overcome with additional investigation. / Master of Science

In this thesis an approximate method is developed which predicts the aerodynamic force on a cone-cylinder body in axially symmetric transonic now. The method places more emphasis on the physics of the now than on the mathematical rigors of solving the typical reduced non-linear transonic equation of motion. Under the assumption that the now is that of a steady, irrotational, inviscid, compressible gas, the body pressures are determined and the associated force defined. Recognizing that the transonic pressures are influenced by the character of the subsonic compressible pressures, which are obtained in this analysis through Gothert’s Rule, it is then mandatory that the incompressible case be defined with the best possible accuracy. Comparisons with experiments indicate that the classical method (axially distributed sources and sinks) does not provide this required accuracy. Thus the surface distributed vortex ring theory is used in the present analysis to obtain the incompressible body pressures. Gothert’s Rule, which represents a linear solution for the subsonic case, is known to be applicable up to a limit value of tree stream Mach number. An investigation is carried out herein to determine both the correct form of the rule and its limits of applicability. As a result of this investigation, it is concluded that the upper limit is the lower free stream critical Mach number. Also, at this Mach number, a solution is immediately available tor the lower limit of the transonic range of Mach number. In solving the transonic problem the law or stationarity of local Mach number is of fundamental importance. For an assumed isentropic flow over the body, and for sonic conditions being present at some point on the surface, the body pressures can be described in the ratio p_L/p*. Here p_L is the local surface pressure and p* is the sonic (body) pressure. Through the stationarity law, this ratio is recognized as an invariant for transonic speeds so long as the flow field remains essentially irrotational. Thus any change in local pressure is only a function of the free stream Mach number for any given body position. By this approach, the pressure distribution is defined for a range of Mach number from below to above the sonic stream value. The method is then capable of prediction for almost all of the transonic range of Mach number. It is only when the head shock baa significant curvature, causing the now adjacent to the body to be rotational, that the method fails. Though the procedure developed here is not capable of spanning the entire transonic range, it does provide a wider range of applicability than other known theories. Finally, for this problem, a correlation of transonic pressure drag data is formulated. This correlation is founded on physical interpretation and is not limited to the usual transonic similarity restrictions. In fact, to the author's knowledge, this is the first known such correlation tor axially symmetric flow covering the range of body sizes and Mach numbers considered in this investigation. In so far as is practicable the results obtained in this thesis have been compared to available experimental results. In particular, the drag data from this analysis compare closely with experimental transonic values. Experiment bears out the conclusion that the upper limit for linear theory is the lower critical tree stream Mach number. And, the pressures determined by the vortex ring theory agrees well with the low-speed experimental results obtained by the author. / Ph. D.

The primary purpose of this thesis is to discuss the protectionist policy of the first Republic of Ghana (1957-66). In particular it attempts to evaluate the performance of the key sectors of the economy under the policy using empirical and statistical data for the period and shortly thereafter. Such discussion is of paramount importance since it provides an insight into what future developmental and growth strategy needs to be adopted for Ghana. While avoiding the social, political and ideological discussions of the policy, the thesis provides an insight into the political atmosphere at the time and the ideological inclinations of the Leaders. The thesis begins by looking at the salient features of the economy of Ghana before independence. It then gives a brief background of protectionism in Ghana and the philosophy that led to its adoption. How the policy was implemented is also discussed. A theoretical background of the effects of protection and a sector by sector analysis and evaluation of the effects of protectionism in Ghana forms the substance of the thesis. While the focus of the discussion is on the first government of Ghana and its protectionist policy, an attempt is made to look at subsequent governments and their deviation, if any, from protectionism. An assessment of the policy arrived at the conclusion that while the leaders had been nationalistic about the policy, their adoption and implementation of the policy was nothing less than an economic blunder. / M.A.

The East River Mountain district. located in Tazewell and Bland counties. Virginia. is an area of approximately 80 square miles much of which is underlain by ferruginous sandstones of Clinton age. The extensive areas of outcrop of the ferruginous sandstone make large tonnages of the rock readily available for open-pit quarrying. Investigations show that within the area studied over 60 million tons of hematite were contained in the ferruginous sandstones present in the East River Mountain district. Thus these sandstones constitute a large potential for commercial iron ore if extraction is possible. In September of 1956 9 laboratory study of the ironbearing sandstones was inaugurated primarily to discover a commercially feasible method of beneficiating and concentrating the hematite contained in the sandstones. High-tension electrostatic, wet and dry magnetic. and ultrasonic methods of extraction were studied. Of these methods ultrasonic insonation of the ferruginous sandstone appears to hold the most promise for obtaining satisfactory concentrates of hematite from the sandstone. A marked upgrading of the hematite content was noted after the crushed iron-bearing sandstones were subjected to ultrasonic insonation at a frequency of 22 kilocycles. The ultrasonic treatment used to concentrate the hematite appears to be both adaptable and economical on a commercial scale. / Master of Science

This study was undertaken to determine the influence or seasonality on marketings, farm price and cash production cost of broilers in the 10-County Shenandoah Valley Area, The association between the seasonal pattern of broiler marketings and the seasonal variation in broiler prices and the relationship of seasonal variations in cash production cost to the seasonal movement of broiler marketings were also determined. Weekly, rather than monthly data were used in the construction of various seasonal indexes. / Master of Science

At least five million heifers are raised annually in the United States to maintain the dairy cattle population and provide for our future needs. These animals are in reality the very foundation of the dairy business and the prosperity of everyone connected with it are dependent, at least to a certain extent, upon how well and how economically these animals are produced. Any practice that might possibly increase the efficiency with which these animals are raised is certainly worthy of thorough study and consideration. In the past the livestockman has paid little attention to the effect that frequency of feeding may have on the efficiency with which his animals convert feed to milk, meat, and. eggs. This is surprising when one considers the feeding behavior of the animal in its native or unconfined state. In its wild state the animal took in food throughout the day and also undoubtedly at night. The quantity eaten and the frequency of intake was entirely dependent upon the desire of the animal and the availability of feed. This condition still exists to a very large extent in the case of the free-grazing animal. However, with the closely confined or hand-fed animal both the quantity of feed eaten and the frequency of intake are regulated according to the judgment of the husbandman. Since this is a definite change from the feeding habits of the animal in its native state, it is conceivable that some change in the efficiency of feed utilization, if not the overall physiology, of the animal has occurred as a result of domestication. Like the livestockman the research worker has considered frequency of feeding to have little or no influence on his research results. A limited amount of work (15, 70, 27) has demonstrated that frequency of feeding is important in livestock production. If additional work confirms these results, it will become necessary to interpret past feeding experiments in the light of these new findings and to give more attention to frequency of feeding in future nutritional research. Such information would be of considerable practical importance since it would be a comparatively simple matter to design automatic feeders which would feed animals at periodic intervals. The present study was initiated to obtain data on the differences in body weight gain, digestion coefficients, heart rate, rectal temperature, rumination time, and rate of passage of food of dairy heifers fed equalized intakes of feed two and ten times daily. / Master of Science