No description available.

M.S.

The purpose of this study was to determine change in enrollment and completions in vocational programs in a phase-elective, non-graded, flexibly scheduled curriculum in Maury High School, Norfolk, Virginia, through comparison with the enrollment and completions in vocational education in a traditionally organized and scheduled curriculum in the same high school. The time period of the study was five years. The time series design was utilized to analyze data. The population consisted of 11,002 students who were enrolled at Maury High School from September, 1970, through June, 1975. The population ranged from a low of 1,920 students in 1974-75 to a high of 2,450 students in 1972-73. Students assigned to Maury High School who elected to pursue a vocational program at the Norfolk Technical Vocational Center (NTVC) were included in the study. Conclusions reached included: (1) initial implementation of a phase-elective, non-graded curriculum increased enrollment in vocational programs, (2) enrollment in vocational programs tended to decline after the initial implementation of a phase-elective, non-graded curriculum, (3) completions tended to decrease with the implementation of a phase-elective, non-graded curriculum, (4) enrollment and completion patterns seemed to be less stabilized in the phase-elective, non-graded curriculum program, and (5) the number of students selecting multi-period vocational courses tended to decrease. Recommendations included: (1) follow-up studies should be conducted by Norfolk Public Schools to develop patterns of student enrollment and completions of vocational programs in the phase-elective, non-graded curriculum, (2) this study should be replicated in other areas with comparable school size and student population in order to ascertain more explicitly the effects of a phase-elective, non-graded curriculum on the enrollment and completions in vocational programs, (3) a study should be made of student competencies developed in a phase-elective, non-graded curriculum as compared with a traditional curriculum, (4) further investigation should be undertaken to ascertain if the location of vocational courses away from the home school in a separate technical-vocational center has an effect on student enrollment, (5) corrective action should be taken by the Norfolk Public Schools to offset the decline in enrollment and completions at the Norfolk Technical Vocational Center from Maury High School, (6) emphasis should be placed on exploration and tryout of vocational programs early in the student's secondary program of studies, (7) intensified courses compatible with the phase-elective, non-graded curriculum organization would be developed, (8) changes in curriculum organization should enhance the enrollment and completions in vocational programs to reflect the current emphasis on job-entry skills, and (9) completion criteria should be reviewed by the Virginia State Department of of Education to permit more flexibility in vocational programming. / Ed. D.

M.S.

Glucocorticosteroids are drugs commonly used to suppress immune or inflammatory responses. The present study was done to evaluate the influence of glucocorticoids on immunity in fibrosarcoma-bearing mice. Effects of hydrocortisone-21-sodium succinate (HCS) on mitogen-induced lymphocyte proliferation were assessed. T cells from nontumor-bearing mice showed a 2-fold suppression of phytohemagglutinin (PHA) responsiveness with the addition of 0.1 µg HCS. However, T cells from mice with 3-4 week tumors did not demonstrate as great a suppression, if any. Kinetic studies during tumor growth demonstrated a decrease in HCS suppression of mitogen-induced DNA synthesis at 8-10 days post-tumor cell inoculation. RCS-treated cells from mice with 3-4 week tumors had a 2- fold increase in blastogenesis over untreated PHA controls. The role of macrophages and their involvement in the steroid sensitivity of the PHA response is unclear. Evidence reported here indicated that macrophages may be involved as mediators of steroid sensitivity and may therefore limit the extent of their suppressive and/or enhancing activity. In vivo administration of methylprednisolone acetate (MPA) demonstrated that steroids can interfere with the growth and progression of fibrosarcomas in their syngenic BALB/c hosts. The strongest delay in tumor appearance was observed when the steroid was administered 4-7 days post-tumor cell inoculation. It is assumed that after tumor cell inoculation, precursor cells of both suppressor and cytotoxic lymphocytes were entering a proliferative stage to form mature cells. These studies indicated that steroid suppression was directed against a suppressor T cell and possibly acts by preventing its differentiation. It is thought that this suppressor cell acts by inhibiting the lytic function of effector T cells. Thus, by eliminating suppressor T cells, the immune response is capable of eliciting strong anti-tumor immunity. / M.S.

Analytical expressions for the deflection surface of symmetrically loaded circular and annular plates resting on discrete point supports are derived. The formulation of the problem is based on classical small deflection plate theory. It is also assumed, in the formulation, that the supports are situated equal distances apart on a single concentric circle. There is no restriction placed on the number of supports or on the size of the support circle which could be as large as the plate itself or as small as the size of the hole of the annular plate. The singularity effects associated with the concentrated supports on the plate problems considered here are accounted for in the solution, by drawing an analogy from the Michell's solution to a clamped circular plate subjected to an eccentric point load. This procedure yields solutions in much more suitable form for practical numerical problems than other known methods. In the case of circular plates on multipoint supports, explicit solutions are given to a number of loading conditions. Solutions to a uniformly loaded circular plate on multipoint supports are compared with the published experimental results; the conclusions are favorable. From the numerical data obtained for a uniformly loaded circular plate on multipoint supports, a procedure is outlined for obtaining contour maps of deformed uniformly loaded plates with discrete supports on two support circles. Solutions to annular plates on multipoint supports are derived for the first time. By utilizing this result, design charts are drawn to indicate the optimum size of the support circle, which would produce least peak-to-peak displacements for any given size of hole, and a specified number of supports. Contour maps associated with annular plates on three point supports are also drawn to illustrate the influence of support circle on the displacements. It was found that when there are a fewer number of supports and/or the size of the hole is small, the magnitude of peak-to-peak displacements and the size of the optimum support circle are considerably different from the associated quantities when the support is a continuous ring. / Ph. D.

Two models of a Durkheimian explanation of crime rates were subjected to empirical test. One is the static model which posits that in a more complex society the crime rate ought to be higher. This proposition is based on the assumption that in more complex or organic societies the probability of anomie is greater which is reflected in the rate of crime. The research proposition of this model is that there is a direct relationship between the joint effects of the level of population size, population density, urbanization, the division of labor and the rate of crime. The other model, the change model, is concerned with how the transformation of societies influence social behavior. This model is based on the proposition that crime is more likely in those societies or communities in which a greater degree of structural change from mechanical to organic solidarity occurs. The basic research proposition of this model is that there is a direct relationship between the combined action of change in population size; population density, urbanization, the division of labor, and change in the rate of crime. Data concerning crime rates were provided by the Uniform Crime Reports Division of the Federal Bureau of Investigation and data concerning the independent variables were obtained from the United states Census Bureau volumes. The basic unit of analysis is the county, chosen largely because it encompasses both rural and urban dimensions of a society. Counties were selected according to the availability of the crime rate data. The total number of counties selected in this manner is 300. The basic statistical procedure used is multiple regression analysis. Finite first difference equations were used in testing the change model. The propositions were tested for four time periods: 1940, 1950, 1960, and 1910. The results indicate that the rate of property-theft offenses (i.e., auto theft, robbery, grand larceny) are best predicted by both static and change models. Both models also are most effective in predicting these rates of crime in the more urban counties. The indication, thus, is that the probability of anomie is greater in the more complex (i.e., organic) communities than in the less complex ones (i.e., mechanical). The main factors in the static model in predicting the crime rates are urbanization, population size, and population density, while in the change model population size and population density predominate. The division of labor has very little influence in either model. It is suggested that the models are only supported in part and that a reformulation of a Durkheimian explanation of crime rates is in order. This modification centers on the components of urban life which are more likely to foster an increase in crime. Communities which are smaller and less dense, homogeneous, and mechanical-based are apparently more solidary and as a result have a lower crime rate. It is proposed that this social solidarity is often eroded when such a community experiences an economic and industrial transition. / Ph. D.

An artificial larval medium for colonized Culicoides guttipennis was developed. Microorganisms in decaying leaf matter were present in the original laboratory diet. These were believed to be the main food of C. guttipennis larvae. This was verified by sterilizing the leaf matter to kill the organisms present. Larvae did not develop beyond the first instar in this medium, but adults were produced from non-sterilized leaf matter. The objective was to develop cultures of various microorganisms and find one that would be best for rearing C. guttipennis larvae in producing more adults. A simple hay-infusion medium inoculated with stump-hole microorganisms was found more effective than all other cultures screened in rearing the larvae. This culture consisted of stump-hole microorganisms inoculated fresh each week from stored stumphole contents. It was compared with the same culture containing stumphole microorganisms completely adapted to a laboratory environment. The former was better in rearing C. guttipennis larvae. A final experiment evaluated the incorporation of vermiculite as an artificial substrate. This proved successful in rearing larvae and producing large numbers of adults. This culture was superior over the larval rearing medium of decaying leaf matter. Development of a successful artificial larval medium for colonized C. guttipennis will aid in establishing other laboratory colonies of related Culicoides species. / Master of Science

I. Introduction. II. Production of Sanitary Milk. III. Milk as a Disease Distributor. IV. Pasteurization of Milk. V. Methods of Bacterial Count. VI. Intensive Study of Desirable and Undesirable Bacteriain Milk. VII. Conclusion. VIII. References / M.S.

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