Data from 946 Angus and 351 Simmental females were used to quantify relationships between calfhood and early-life traits of females with fertility in the first two breeding seasons, and with calf production in the first, in three and in eleven years of life. These traits were used to develop prediction equations for fertility using logistic regression methodology. For productive performance, three methodologies were compared: least squares, ridge regression and principal components regression. For heifers of both breeds, fertility was associated with birth date, weaning weight ratio and weaning-yearling relative growth rate (RGR). The only calfhood trait that consistently affected fertility in the second breeding season was birth weight of the cow. Fertility of first parity Simmentals was also associated with birth-yearling RGR. First calving season traits explained a higher proportion of variation in second breeding season fertility than calfhood traits of the cow. Among these traits, calving date, calving ease score and sex of the calf were the most important. The combination of birth date and weaning-yearling RGR produced the best models to predict heifer fertility for both breeds. Fertility in the second breeding season was best predicted for Angus cows when calving date, calving ease score and sex of the calf were used as regressors. For Simmental cows, fertility in the second breeding season was best predicted from birth weight of the calf and calving ease score. The regression of weaning weight of the first calf on pre-selected calfhood traits was used to evaluate models produced by least squares, ridge regression and principal components regression. Although biased, the regression coefficient estimates produced by ridge and principal components regression had smaller variances than estimates obtained from least squares. Between the two alternatives to least squares, ridge regression produced better results than principal components regression. Ridge and least squares regression were quite similar in their regression coefficient estimates, in prediction sum of squares (PRESS)-like statistics and, to a lesser extent, in conceptual predictive criteria (C_p)-like statistics. For prediction, the performance of models produced by least squares and by ridge regression were very similar. For analyses of the production traits, least squares regression models for all possible combinations of pre-selected regressor variables were fit. Birth date of the female was negatively associated with the weaning weight of the first calf, and with number of calves weaned, total weaning weight of calves produced and average weaning weight of calves in the first three years of productive life. Age of the dam affected early-life production traits of daughters, as well as the average weaning weight of calves produced per year of productive life and calf survival in eleven years. Heavier females at birth tended to produce smaller number of calves and lower calf weaning weight through their lives than females lighter at birth. Overall female productivity was consistently more positively associated with yearling than with weaning growth traits. Among traits observed in the first calving season, calving date, calving ease score, sex and weaning weight of the calf were associated with subsequent production. Weaning weight of the first calf was always positively associated and it was the most important variable to predict female production, except for survival rate. Prediction equations for production in three years included birth date, birth weight of the female, calving ease in the first parturition, sex of the calf and weaning weight of the first calf. This latter variable was the only one useful to predict production in eleven years. Average calf weaning weights in the first three years of production were best predicted using yearling weight ratio or weaning-yearling ADG and first calf weaning weight. Models including age of the female’s dam best predicted weaning weight of calves per year of productive life in eleven years and calf survival. / Ph. D.

The single fiber pull-out test was employed to experimentally model the failure of an embedded optical fiber in neat resin. The objective was to evaluate load transfer between resin and fiber through the evaluation of the sensitivity of the single fiber pull-out test to the physical parameters of the polymer matrix. This was accomplished first by appropriately interpreting the load versus extension trace, second by determining the effect of fiber coating and embedding resin on the load carrying ability of the single fiber composite, third by characterizing the fiber/coating/resin system with respect to the physical parameters of the polymer and the failure mechanism of the composite as the cure temperature was varied, and fourth, by correlating the independent parameters of the polymer and fracture data. For the first time, the load versus extension trace generated by such experiments was thoroughly interpreted and mathematically modeled. To this end, the embedding resin was physically characterized through the determination of the glass transition temperature, T_g, the relative change in volume with sample preparation and thus the resulting normal pressure exerted on the embedded fiber by the resin material. The experimental fracture data was quantified by determining the strain energy release rate, SERR, for initiation of crack propagation and, with the consideration of friction, its continuation, as well as the interfacial shear stress, τ, of the bond, and τ associated with debonding and sliding. Based on a series of experiments of varying material parameters, a model material system was chosen: a polyimide coated fiber embedded in uncatalyzed tetraglycidyl-4-4'-diaminodiphenylmethane with 4,4’-diaminodiphenylsulfone. Cure temperatures, T_cure, of 150, 177, 230 and 250°C were employed. The average critical strain energy release rates increased from the 150 to 177 to 230°C sample sets, then decreased for the 250°C sample set. Since the T_g of the fully cured resin is 260°C, these results support the hypothesis of increasing residual stress as a function of T_cure for cure in the vitreous state. In regards to the 250°C cure data set, since T_cure was within T_g - 30°C the internal pressures due to crosslinking were minimized due to cure in a rubber-like state. The residual pressure, independently determined from both the resin characterization and fracture data, increased by a factor of 2.4 with a temperature increase from 150 to 230°C for the two hour cure period. The strain energy release rate and sliding interfacial shear stress of pull-out increased by a factor of 2.54 and 2.1, respectively. The coefficient of friction remained statistically constant at 0.6. Based on this work, it is concluded that the single fiber pull-out test is sensitive to fiber/matrix interactions via the physical parameters of the material system. Also, the failure response of the single fiber composite can be predicted for well characterized matrices. / Ph. D.

Shear zones which deform margins of amphibolite boudins in the Cheyenne Belt, SE Wyoming, record a full strain transition from relatively undeformed amphibolite which has relict igneous textures to mylonitic amphibolite with a strongly developed L-S tectonic fabric. The strain transition is marked by the rotation of amphibole and plagioclase aggregates into parallelism with the shear zone boundary and progressive grain size reduction. These observations indicate that strain magnitude increases across the shear zone. Detailed petrologic and microstructural analysis of a single amphibolite shear zone has been conducted in order to: 1) document the petrologic and microstructural evolution of the shear zone and 2) investigate the interrelationships between mechanical and chemical processes associated with shear zone formation. Amphibolites throughout the shear zone consist of amphibole + plagioclase with only minor amounts of quartz + chlorite + epidote + sphene + ilmenite. Within the relatively undeformed amphibolite, amphibole and, to a lesser extent, plagioclase has wide compositional variation. Amphibole compositions vary from actinolitic hornblende to magnesio-hornblende which involves increases in Al, Fe, Na and K contents and decreases in Si and Mg. Plagioclase compositions vary from Angp in cores of plagioclase grains to Anjo within grain boundary domains. With increasing strain magnitude across the shear zone variation of amphibole composition decreases and become predominantly magnesio-hornblende. Plagioclase compositions also decrease in range although grain boundary domains still have higher albite content. The observed variation of amphibole compositions indicate that shear zone formation occurred during prograde metamorphism although compositional changes may also be a function of changing grain boundary fluid composition. These petrologic data indicate that shear zone metamorphism was in part controlled by the magnitude of strain during deformation. Scanning electron microscope back-scattered images and color enhanced X-ray compositional maps indicate that compositional variation in plagioclase and amphibole occurs along margins of highly angular grains of various sizes. These textural observations have been interpreted to indicate that chemical reactions occurred by a dissolution and reprecipitation processes following or during cataclastic deformation. Transmission electron microscope (TEM) images show local zones of high dislocation density adjacent to microcracks suggesting that work hardening may have been an important processes during cataclasis. Alternatively, microcracks may have acted as source for development of dislocations. The importance of deformation in assisting shear zone chemical processes is evidenced by: 1) the observation of new mineral overgrowth along grain boundaries and 2) TEM images of amphibole which show that actinolitic hornblende has a high defect density whereas magnesio-hornblende overgrowths are relatively defect free. This observation suggests that strain energy associated with dislocations may have contributed to the chemical process. Thermodynamic modelling of reaction progress within the shear zone using the Gibbs Method indicates that observed modal and compositional changes can occur isothermally if strain energy is added to the system. Increases in reaction progress with deformation may have also been due to increases in fluid infiltration or diffusion due to grain size reduction. The general conclusion of this study is that in order to apply petrologic, geochemical and isotopic data to understanding geochemical and tectonic processes, microstructural information on the magnitude of strain and the type of deformation mechanism must be evaluated, quantitatively if possible. / Ph. D.

Soybean cultivars (Glycine max (L.) Merr.), "Dare", "Williams" and "Essex", with differential sensitivity to ozone (O₃) based on visible injury were exposed once to 0.20 µl⁻¹ O₃ and/or 0.70 µl 1⁻¹ sulfur dioxide (SO₂) for 4 hr. The cv Dare was considered sensitive, cv Williams intermediate and cv Essex tolerant to O₃. Cultivars exposed to filtered air served as controls. Gas exchange measurements were conducted and antioxidant metabolites (reduced and oxidized glutathione: GSH, GSSG; reduced and oxidized ascorbate: AA, dHAA) concentrations and enzymes (glutathione reductase: GRase; ascorbate peroxidase: APase; superoxide dismutase: SOD) activities were analyzed. Gas exchange rates of all cultivars were significantly inhibited by pollutants exposure. The cv Essex maintained significantly higher net photosynthesis (Pn) at the end of 03 exposure, during the SO₂ exposure and in the first 2 hr of O₃/SO₂ fumigation. During O₃/SO₂ exposure, the estimated pollutant fluxes were 50% and integrated doses were 25-30% of O₃ or SO₂ when fumigated singly. During O₃ fumigation, cv Dare exhibited a higher O₃ flux and integrated O₃ dose. However, cv Essex showed a higher O₃/SO₂ peak flux in O₃/SO₂ fumigation. The cv Williams showed the lowest pollutant flux in all treatments. Ozone fumigation imposed a substantial, but statistically insignificant, effect on some antioxidant components. Relative to the controls, O₃ exposure resulted in increases of GRase and SOD activity in cv Dare. In cv Williams, decreases of GSSG and SOD total activity and increase of dHAA were observed. Decreases of AA and SOD activity and increases of GSSG, dHAA and APase activity in cv Essex were found. The SO₂ exposure resulted in increases of glutathione, particularly GSSG, in all cultivars. The cv Dare responded with increases in AA, APase specific activity and SOD activity. In cv Williams, AA and SOD specific: activity increased and APase activity decreased. Decline of SOD activity in cv Essex was found after SO₂ exposure. The O₃/SO₂ fumigation resulted in increases of glutathione, particularly GSSG, and GRase activity, in all cultivars. Declines of dHAA and SOD activity in cv Williams were found. The cv Essex responded with a decline of AA and increases of dHAA and specific activity of APase and SOD. Ozone and SO₂, singly or in combination, inhibited gas exchange rates in all cultivars, however, cv Essex was the least affected. Stomatal conductance was inhibited greater by O₃ than by SO₂ fumigation. Conversely, Pn was suppressed more by SO₂ than by O₃. The O₃/SO₂ fumigation, however, suppressed Pn and Cs substantially and to a greater extent than individual pollutants. Under the pollutant dose and fumigation profile used in these studies, no consistent responses of different antioxidant components to O₃ and/or SO₂ correlated with differential sensitivity of these soybean cultivars as determined from foliar symptomology. / Ph. D.

The problem in this study was to ascertain the demographic characteristics and the tasks performed by elementary assistant principals in the Commonwealth of Virginia. Additionally, this study sought to ascertain how elementary assistant principals were assigned to their positions, what their career aspirations were, what training had contributed most to their success, what their greatest hindrance had been, how their tasks had been assigned to them, and the changes they had seen in the position in the past as well as what changes they anticipated in the future. The Elementary Assistant Principals survey was mailed to elementary assistant principals in the Commonwealth of Virginia. Three-hundred and four questionnaires were mailed and two-hundred and six were returned. Seventy-four percent of the respondents returned the questionnaires. The findings in this study reveal that elementary assistant principals in the Commonwealth of Virginia are typically middle aged males and they are involved in many of the tasks generally associated with elementary administration. The primary tasks of the assistant principals were in student discipline, student transportation, textbook inventories and administering the schools special education program. Elementary assistant principals in the Commonwealth of Virginia were least likely to be involved in tasks related to the school’s financial activities. Fifty task items were distributed across six functional categories including: community relations, curriculum and instruction, staff and personnel, student activities, school management, and student services. Conclusions based on the results of this study indicate the importance of the principal in the training assistant principals through on-the-job training. A critique of this research study, as well as recommendations for further study are also included. / Ph. D.

This research addresses the question, can dispositional complements to situational self-congruity and situational functional congruity be identified? Self-image congruence research, which establishes a background for the situational impact of image and function-laden information, is reviewed. A theoretical rationale for developing dispositional measures is based on the interactionist paradigm in personality psychology combined with self-congruity theory and Blake and Mouton's orientation to tasks vs. people. It was hypothesized that the dispositional measures of self-congruity and functional congruity would moderate the relationship between situational self-congruity and functional congruity and the adoption of a brand of credit card. Results supporting this hypothesis would provide evidence of the nomological validity of the dispositional measures. A 2 x 2 x 2 x 2 factorial experimental design involving situational self-congruity, situational functional congruity, dispositional self-congruity and dispositional functional congruity was operationalized with ads for the Sierra Club credit card providing image and/or function-laden cues. Manipulation checks in the form of situational evaluations and behavioral measures in the form of credit card adoption were ascertained. Pretests were conducted to generate and refine items for the dispositional scale and to initially assess reliability and validity. Subsequently, a main study was conducted involving 320 students from two universities. The results show that the dispositional measures are highly reliable. Dispositional measures were also shown to have discriminant validity, however, the tests of nomological validity indicated that these measures may not be valid. This study emphasizes the importance of considering the coaction of situational and dispositional factors in understanding behavior. Limitations of the study, future research, and managerial implications of the findings are discussed. / Ph. D.

Finite state test theory models the response behavior of an examinee and establishes the relationship between the ability of the examinee and the observed responses on a multiple-choice test. In finite state modeling, various assumptions about item characteristics and the examinees’ response strategies are made to estimate an examinee ability, and willingness to guess. Twelve sets of plausible assumptions about identifiability of distractors and examinee guessing strategies were adopted and the corresponding finite state models were actualized. Three consequences of the adoption of the 12 sets of assumptions were investigated: 1) the extent to which the resulting ability estimates rank ordered the examinees similarly, 2) variation in the magnitude of ability estimates and the estimated willingness to guess across the 12 models, and 3) the extent to which conclusions about examinees subgroups would differ according to the model employed. Also, conventional number-right scores were compared with the finite state scores with respect to the three outcomes just listed. All scoring methods rank ordered the examinees essentially the same. The magnitude of the finite state scores varied considerably across models mainly due to differing assumptions about the identifiability of distractors. Differing assumptions about examinee guessing strategy had surprisingly little effect on the magnitude of the ability estimates, though estimates of willingness to guess varied consistently according to the assumed strategies. Conclusions about group differences also varied across the models as a result of differing assumptions about both item characteristics and examinee guessing strategies. / Ph. D.

Two studies were conducted to evaluate the effects of varying dietary sources of rumen available carbohydrate (RAC) and rumen available protein (RAP) on milk yield and milk composition, nutrient flow to the duodenum, ruminal and total tract nutrient digestibilities, and ruminal pH, ammonia-N, and VFA concentrations in lactating cows. The first study was a response surface design utilizing nine dietary combinations of RAC and RAP. The response surfaces of all milk variables were saddle-shaped. Because of the saddle-shaped surfaces, an optimum combination of RAP and RAC for milk production variables was not obvious from the limited range of RAC and RAP used in this study. Ridge analysis of the saddle surfaces predicted maximum milk yield when dietary RAC was below 69 % of the DM and RAP below 60% of CP in alfalfa-corn silage based diets. In the second study, four cannulated (ruminal and duodenal) cows were utilized in a 4x4 Latin square design. Four of the nine original diets were selected to provide the largest range of RAC and RAP. Nutrient flow, digestiblities and ruminal parameters were evaluated. Although the in situ incubations indicated that rates of DM, CP, and NDF degradabilities differed among diets, no effects on overall ruminal pH and total VFA concentrations were detected. Additionally, DM, OM, NDF, ADF, and N flows to the duodenum were not affected by dietary treatment. Nonmicrobial N flow was greater for the barley-based diet, yet microbial flow was not different. The differences in rates of availability determined by in situ methods were not large enough to illicit a measurable difference in nutrient digestion and utilization. Additionally, the data implied that none of the diets were limiting in RAC and RAP for vigorous microbial activity. Fat-corrected (3.5%) milk production was greatest (P<.05) when alfalfa-corn silage based diets contained supplements providing intermediate (69 % RAe) carbohydrate availability (corn and barley) and low (60 % RAP) ruminal protein availability (BM and SBM). The increase in fat-corrected milk was consistent with the predicted milk production response in the previous study when RAP exceeded 62% of CP. However, the ruminal parameters, nutrient flow, and nutrient digestibility measurements did not adequately explain the increased milk production when diets contained increased concentrations of BM. / Ph. D.

The purpose of this study was to explore the influence of the Navy Junior Reserve Officer Training Corps (NJROTC) program on cadets in the program and to determine the extent to which it was effective in achieving its stated goals of promoting patriotism, discipline, leadership, respect for authority, and knowledge of the U.S. Navy. The study specifically sought to address the question of why high school students join and remain in NJROTC, and the sub-questions of what aspects of the NJROTC program are associated with participation; what are the characteristics of high school students who participate in NJROTC; what experiences prior to involvement in NJROTC are associated with participation; and what aspects of NJROTC are associated with intent to remain as participants. A 49-item survey instrument was designed, content validated, and administered to 223 NJROTC cadets in three Virginia high schools. Descriptive statistics and Chi Square analysis were used to answer the research questions. Primary results indicated that joining NJROTC was associated more with personal contacts (friends, teachers, and school administrators) than with broad based Navy efforts such as radio and magazine advertising. Cadets indicated NJROTC involvement was associated with improved grades, better self concept, increased desire for leadership, maturity, and awareness of need for community service. The highest portion of cadets were clustered in lower grades (9th and 10th) and apparent attrition was most pronounced in the urban school with high minority enrollment. Over 40% of the respondents indicated plans to engage in a military career after graduation. / Ed. D.

The effects of dietary folic acid supplementation on serum folate status, conceptus development and reproductive performance in gilts and sows was investigated in a series of experiments. The specific objectives of the study were to: 1) to study the serum folates profile following rapid consumption of a single meal containing different levels of supplemental folic acid; 2) to study the effects of maternal folic acid supplementation on conceptus survival, growth and development prior to mid-gestation in gilts and sows; and 3) to study the effects of multiple levels of dietary folic acid supplementation on sow reproductive performance over four successive parities. In the first experiment (Chapter III), gilts fed a single, rapidly consumed meal, had a rapid increase in serum folates concentration during the first hour postprandial. Within eight hours after feeding, serum folates in the gilts had returned to near prefeeding levels. The results also suggest that supplementing the diet with increasing levels of folic acid over a range of 0 to 4 ppm results in more rapid postprandial uptake and elimination of folic acid from general circulation. In the second experiment (Chapter IV), supplementing the diet of first parity and third parity breeding sows with 2 ppm folic acid had no effect on litter size at day 45 of gestation. However, several measurements associated with placental and fetal growth were increased with folic acid supplementation. Results of a fifth parity trial with four levels of supplemental folic acid were variable and inconclusive. The implications of increased placental and fetal growth up to day 45 of gestation in the first and third parity sows is discussed. In the third experiment (Chapter V), a decline in serum folate concentration in pregnant sows from mating to mid- to late gestation was clearly demonstrated. Supplementing the sow's diet with folic acid over a range of 0 to 4 ppm resulted in a linear increase in serum folate concentration at mating, during gestation and at weaning. However, under the conditions of this experiment, folic acid supplementation had no significant effect on sow reproductive performance. / Ph. D.