Public school districts in the United States that completed feasibility studies on year-round schools during the last ten years were the population for this study. These districts were divided into three categories--those that did not implement a year-round program, those that implemented a Restricted Model, and those that implemented a Full-Scale Model--to study their characteristics. Both a Restricted and a Full-Scale Model of year-round schools required at least 220 days during the calendar year for attendance of students. Only the Full-Scale Model required the number of students enrolled in a school from its own attendance area not to vary more than ten percent at any time during the school year; the Restricted Model permitted the enrollment to vary more than ten percent. One-hundred seventeen school districts were surveyed by questionnaire to determine if differences in their characteristics had value for predicting into which of the three categories they would fall. This study indicated that the most important predictor of whether or not a district implemented year-round schools was the attitude of teachers, administrators, parents, students, and business/industry toward implementation. It also indicated that more Full-Scale Models of year-round programs were implemented in elementary schools and more Restricted Models were implemented at the secondary level. Other characteristics of the school districts could not be used to predict their implementation category. A list of the 117 districts categorized into three implementation groups, a list of 53 districts with studies in progress, a description of the investigation, and suggestions for further study are included. / Ph. D.

The effects of solvent, base strength, nature of halide, number of equivalents of base, and number of equivalents of halide on the course of C-alkylation of 2,4-oxazolidinedione and 5-phenyl-2,4-oxazolidinedione were investigated. The highest isolated yield (49%) of 5-benzyl-5-phenyl-2,4-oxazolidinedione was obtained using 2.1 equivalents of lithium amide in liquid ammonia followed by alkylation with 1.1 equivalents of benzyl chloride. Although the yield of 5-benzyl-5-phenyl-2,4-oxazolidinedione using lithium diisopropylamide in THF-hexane-HMPA was only 39% (determined by pmr analysis), the addition of HMPA as a co-solvent had a beneficial effect on the ratio of 5-phenyl-2,4-oxazolidinedione to the benzyl derivative. The addition of HMPA as a co-solvent in the ethylation of 5-phenyl-2,4- oxazolidinedione using lithium diisopropylamide in THF-hexane increased the yield of the ethyl derivative by 60% over that obtained in the absence of HMPA. Using potassium amide in liquid ammonia, lithium amide in liquid ammonia, lithium diisopropylamide in THF-hexane, or lithium diisopropylamide in THF-hexane-HMPA failed to produce 5-benzyl-2,4-oxazolidinedione in a significant yield. Several attempts were made to form the dianion of oxindole and selectively alkylate it at the 3-position without the interference of dialkylation at that position. No evidence was obtained which indicated that the dianion had been successfully formed, and the major products afforded from these attempts were the 3,3-dialkyl derivatives of oxindole. / M.S.

Forty-seven cottontail rabbits, Sylvilagu floridanus, were used in a 2 x 2 factorial experiment to determine the effects of parasite reduction on host physiology. Rabbits were treated with insecticide-generating collars (Sergeant's Sentry Dog Collar) and a broad spectrum antihelminth drug (Tramisol, American Cyanamid) to reduce parasite burdens. Rabbits were confined in 4 one-quarter acre outdoor enclosures during the treatment period. Thirty-one rabbits were recovered at the end of the treatment period. Data from these rabbits and 10 wild rabbits were analyzed. Treatment with insecticide-generating collars resulted in complete elimination of ectoparasites from rabbits which received this treatment. The two groups of rabbits which received treatment with the drug Tramisol had a significant reduction (p<.05) in the number of nematode parasites recovered. Reduction of nematode numbers was accompanied by significant changes in the generalized blood picture. Total serum protein, serum globulin fraction, lymphocyte percentage, and monocyte percentage were significantly (p<.05) reduced and neutrophil percentage was significantly increased (p<.05) in drug treated groups. A simple correlation analysis was conducted between parasite burdens and select physiological measurements. A highly significant (p<.001) correlation of 0.57 was found between parasite burden and basophil percentage. A highly significant (p<.01) correlation of -0.57 was found between eye lens weights and the presence of Cuterebra maggots. A significant (p<.05) correlation of 0.33 was found between serum corticoid levels and numbers of ticks recovered. These results indicate that parasites may, under some conditions, operate as a limiting factor to cottontail rabbit populations. / M.S.

Gross rainfall and throughfall were measured in an uneven-aged, mixed deciduous forest in western Virginia from August 6, 1972 to June 19, 1973. Storms were grouped according to leafy (growing) season and leafless (dormant) season for analysis of gross rainfall and throughfall. Average leafy season throughfall was 78.2 percent of gross rainfall, and leafless season throughfall was 81.86 percent. Regression of throughfall on gross rainfall explained approximately 99 percent of variation in throughfall. Variations in throughfall were also related to storm characteristics, irregularities of vegetative cover, and different concentrations of throughfall at single sampling positions. Coefficients of variation decreased with increasing amounts of gross rainfall. Throughfall amounts increased with decreasing canopy density over plots. However, an analysis of variance showed no significant differences of mean throughfall among plots. Throughfall caught in several gauges exceeded gross rainfall in 36 of 40 storms. This phenomenon was more pronounced in the leafy season. There was relatively little difference in throughfall between seasons. Soil moisture was determined on two dates. No correlation could be demonstrated between soil moisture distribution and throughfall under the forest canopy. The results, however, were inconclusive, owing to the small number of samples taken. / M.S.

The purpose of this study was to examine the differences and similarities in sex-role perception within the framework of marriage for three age groups: high school, college, and adult. The Marriage Role Expectation Inventory was administered to 259 high school students, 116 college students, and 100 adults. Items on the Inventory were into sub-scales in seven behavior areas: authority, homemaking, care of children, personal characteristics, social participation, education, employment and support. There were statistically significant between the high school group and the other two groups, but there were no significant differences between the college and adult groups. This indicates a trend toward a less equalitarian view of male-female roles in marriage for the high school students. In addition to having a lower mean score, the high school group scored statistically significantly lower than the college and adult groups in all seven subscale areas. The hypothesis tested, that husband/wife role preferences, Traditional versus Equalitarian, will vary independently of: age group, sex the respondents, and educational level of the respondents, was partially rejected. Part (a) of the hypothesis was rejected because the age of the respondents appeared to have a direct relation to the scores on the MREI. Part (b), concerning sex of the respondents, was supported even though the high school males scored statistically significantly lower than the high school females. Educational level was the variable for Part (c) and again the hypothesis was supported. The high school students' mean score was lower than the more highly educated groups', but the adults with a fairly comparable education scored essentially as high as their peers with college degrees. According to this study, the equalitarian view of male-female roles in marriage tends to predominate, but young, high school aged males appear to desire a more traditional arrangement. / M. S.

The purpose of this research was to investigate the relationship between college students knowledge of contraceptive devices and techniques and their attitudes tovra.rd premarital sexual permissiveness. This study also examined background variables of the respondents to determine if they might innuence the relationship between knowledge of contraceptive devices and techniques and attitudes toward premarital sexual permissiveness. The sample was composed of 392 students currently enrolled in two colleges in Virginia. A questionnaire was developed using Reiss' (1964) premarital sexual permissiveness scale, items measuring knowledge of contraceptive devices and techniques devised by the investigator, and items gathering information on background variables. The relationship between knowledge of contraceptive devices and techniques and attitudes toward premarital sexual permissiveness was influenced by each of the following background variables: race, sex, religious denomination, and college major. Also males were found to be more permissive than females while knowledge of contraception was highest among white females followed by white males, black females and black males respectively. / M.S.

Largely as an outgrowth of the promotional efforts of a single man--an industrialist and publisher, John H. Perry, Jr.--a proposal called the National Dividend Plan has received considerable attention. The Plan involves a proposed constitutional amendment which would prohibit the corporate income tax rate from exceeding fifty percent of net income; make corporation dividends nontaxable income to the recipient; and redistribute funds raised by the corporate income tax to those persons ·voting in the last preceding national election in equal amol.Ults on a per capita basis. This study represents an investigation into the implications of the Perry proposal by considering each of its most significant provisions. The proposal has a significant impact on federal government revenues and expenditures. Projected federal budget data for the two decades of the 1970s and 1980s permits examination of these effects. The Plan acts to entrench a less than highly desirable form of taxation, the corporate income tax, however at the same time it tends to rejuvenate the profit motive. The National Dividend Plan may be used to substitute, wholly or in part, for numerous federal functions; for example, the income security program. The provision for the nontaxability of dividends may have numerous repercussions in the way individuals and corporations allocate their portfolios. Finally, the distribution of funds to persons voting in the last preceding national election implies that the new voting population would be younger, poorer, less educated, less white, less suburban, and less employed. Fair evaluation of the National Dividend Plan package requires a clear realization of the existing situation. Thus, the question for the reader is:"Does the National Dividend Plan, considered from a perspective of political and economic feasibility, act to improve the well-being of our society at a reasonable cost or not?" This study does not attempt to answer this question, however, it will aid the reader in evaluating the Plan and answering this question for himself. / Ph. D.

Integral measurements with a ³He spectrometer have been made to test the validity of the differential data of the ENOF/B-II files for thorium, natural uranium and heavy water. The experimental measurements of fast neutron spectra have been in two lattices of thorium metal and D₂O, a cylindrical array of close-packed natural uranium metal slugs in air, a D₂O sphere and cylinder, and a cylinder of thorium nitrate. A ²³⁵U fission disc, irradiated by a beam of thermal neutrons from the V.P.I. & S.U. reactor. provided a fast neutron source. Neutron leakage spectra were taken over the energy range between 100 keV and l.65 MeV. The spectrometer was calibrated using neutrons from the ³H(p,n)³He reaction in a Van de Graaff accelerator. Experimental results were compared with leakage spectra calculated. with the multigroup transport code, ANISN. For the thorium metal and D₂O lattices and for the D₂O sphere and cylinder, agreement between calculated and measured spectra was attained confirming the validity of the ENDF/B-II cross-sections and pointing to the usefulness of the ³He spectrometer for fast neutron leakage spectra determinations. For the natural uranium assembly, the calculated leakage spectrum between about 0.743 MeV and 1.65 MeV was significantly below the measured spectrum. This discrepancy supports a recent suggestion by H. Alter of Atomics International that the ENOF/B-II data files contain significant errors in the transport cross-sections for ²³⁸U and that the suspect data are in need of closer examination and revision. As a further test of the applicability of the calculational procedures and ²³⁸U cross-sections, transport analysis using the ANISN code was applied to predict the central spectrum of the Japanese Atomic Research Institute (JAERI) I-5 fast assembly. These calculations were compared with the results of published ³He spectrometer measurements of the fast neutron spectrum for this 20% enriched uranium assembly. The results of the comparison reveal a measured spectrum slightly harder than the spectrum determined by the calculations using ENDF/BII cross-section data, and gives further evidence to support the conclusions regarding the suspect ²³⁸U data files. / Ph. D.

The motivating idea behind the thesis is the study of the relationship of the degrees of the vertices of a graph and the structure of a graph. To each graph (indirected, without multiple edges) one can associate a graphical sequence by arranging the degrees of the vertices in their natural order. Conversely, an arbitrary sequence of numbers is graphical if it is a graphical sequence for some graph. In the first chapter general properties of graphical sequences are studied. We give conditions under which a sequence can be lengthened or shortened and have the property of being graphical be preserved. The concept of a 'transfer' is introduced to show how all realizations of a graphical sequence can be obtained from a given realization. Also in chapter one we show how graphical sequences can be used to characterize concepts like 'connected', 'block' and 'arbitrarily traceable'. If a graphical sequence has one 'realization' up to isomorphism then the sequence and the graph are called simple. Since simple graphs are determined up to isomorphism by the degrees of the vertices it is hoped that simple graphs will reveal in some measure the effect of the degree sequence on the structure of a graph. Thus, in chapter two, we attempt to characterize simple graphs--the central problem of the thesis. Simple trees, simple disconnected graphs, and simple graphs with cut points and no pendant vertices are characterized. (This means that characterizing simple blocks will solve the problem). Probably the most useful result is that a connected, simple graph must be of radius ≤ two and diameter ≤ three The third chapter is devoted to the problem of counting the number of non-isomorphic realizations of a given graphical sequence. Generating functions are used and several interesting special cases are given. These latter are in turn used to establish certain bounds on the number of realizations for sequences of a given length. / Ph. D.

Physisorption of argon, krypton, and nitrogen on Pyrex and iron was studied by a static technique in a constant volume system, in the temperature range 77.4 to 90.2°K and in the pressure range 10⁻⁹ to 10⁻⁴ torr. Analyses via Electron Spectroscopy for Chemical Analysis (ESCA), Scanning Electron Microscopy (SEM), and Neutron Activation Analysis (NAA) were made to characterize the solid sample surfaces. Both Pyrex and iron surfaces were degreased with ethylene dichloride. The iron surface was further cleaned using the Diversey process. Both surfaces were given a mild bake in vacuum. A modified Dubinin-Radushkevich-Polanyi (D-R-P) theory was used for interpreting the experimental results. This theory assumes that the adsorbed phase is not necessarily liquid-like and is a function of adsorption temperature. Comparisons were made between the modified and the original theories and it was found that the modified theory had a wider applicability and gave better data correlation for all five systems in the present study. It was found that the Dubinin-Radushkevich (D-R) parameter B, and the limiting (maximum) adsorption energy, (π/4)^½ (B), ^-½ of all systems were primarily dependent on the adsorbate. A correlation between the limiting mean adsorption energy and the polarizability of adsorbate was made. From the D-R parameter, N_m, it was found that the effect of the Diversity process on iron was to increase the surface area. Isotherms of the argon/Pyrex system showed that Henry's Law behavior was reached at low coverages and high temperatures. Isosteric heats of adsorption were calculated for all systems. Isosteric heat versus coverage curves indicated that the Pyrex surface was heterogeneous and the iron surface was less heterogeneous. The magnitude of isosteric heats also indicated that all three gases were physisorbed on the Pyrex and iron. Work function measurements were taken simultaneously with the adsorption isotherm measurements. The results were marginal but confirmed that nitrogen was physisorbed on iron. Water contact angles on Pyrex and iron surfaces were also measured. It was found that the contact angle was very sensitive to the surface contamination and that ordinary laboratory air may contaminate the sample surface very rapidly. A finite water contact angle on Pyrex was found instead of a zero contact angle as is generally used in many works. / Ph. D.