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.

The purpose of this study was to describe the profiles, functions, and career experiences of hospital nurse executives in the United States. A descriptive survey method was used. Data were collected from a random sampling of hospital nurse executives and chief executive officers. A self-developed questionnaire was mailed to 400 nurse executives and 300 chief executive officers. The response rate was 40% for the nurse executives and 51% for the chief executive officers. Descriptive statistics (frequencies and percentages) were used to report the findings. Results of the study revealed: 1. The profile of the hospital nurse executive was female, caucaSian, married with children, and between 41 and 50 years old. Nurse executives have more baccalaureate and master's degrees than the general nurse population. Seventy-seven percent of nurse executives have a master's degree in nursing and/or related fields. Nurse executives are in a transitional role from middle to top-level hospital management with title changes, additional responsibilities and increased compensation. 2. The functions of the nurse executive position rated as very important by nurse executives and chief executive officers were similar in the categories of finance, human resource, and nursing management, and less Similar in hospital/organizational management. Nurse executives were not satisfied with educational preparation in financial and hospital/organizational management. 3. The career path to the nurse executive position was identified as the traditional clinical pathway. The majority of nurse executives had worked in six or less institutions, had seven or more positions and had 13 years or more of work experience. Nurse executives stated major factors in career advancement were mentors, networking, education, management experience, strong interpersonal and communication skills, and clinical background. Nurse executives described their career planning as both internally and externally determined. Only a small number planned their careers, and over one-half were determined by the organization. Nurse executives perceived themselves as successful. Recommendations for further research were offered. / Ed. D.

Rapid advances in computer technology over the last few years and their integration into analytical instruments have led to tremendous increases in data collection rates. The need for tools to assist analytical chemists, and especially spectroscopists, in their task of interpreting such vast quantities of data is immediate. This work focuses on the development of an algorithm based on an alternative to the Fourier transform, the Hartley transform, for the qualitative and quantitative analysis of multi-component mixtures using Excitation Emission Matrices. The algorithm involves the reverse search of a compressed reference spectral library for the identification of possible components of the mixture and the method of Non-Negative Least Squares for the quantification of the components. A number of techniques for pre-processing of three dimensional fluorescence spectra along with several spectral encoding methods for the compression of the spectra were investigated. Both simulated and real data collected with a fluorescence spectrophotometer were used in this study. The algorithm proved capable of analyzing mixtures of five components with relative concentrations ratio of about 100:1 and significant spectral overlap. At the same time a compression ratio of about 10:1 for the spectra in the reference library was achieved. Finally, a library of three dimensional fluorescence spectra of some aromatic and poly-aromatic hydrocarbons was developed to be used with the algorithm. Such a library, along with the algorithm, provides a tool for the quick and simple qualitative and quantitative determination of mixtures of aromatic and poly-aromatic hydrocarbons. / Ph. D.

The inorganic chemistries of coal and petroleum differ because of their disparate geologic environments of formation, the physical state of the fuels, and the type and quantity of minerals and organic compounds in the fuels. Commercial coals typically contain 2 to 25% ash (average ~ 10%) while petroleums contain 0.003 to 0.07% ash (average ~ 0.01 %). Globally averaged, coal ash is dominated by Si, Fe, Ca, AI, and S, whereas petroleum ash contains significant quantities of V, Ni, S, Fe, Ca, Na, K, Mg, Si and AI. This larger number of important elements causes petroleum combustion slags to have more complex phase assemblages. The high vanadium contents of petroleum-based combustion feedstocks yield numerous crystalline V -oxides with stoichiometric amounts of Ca, Fe, Mg, AI, Ni andlor Na in the resulting slags. Slightly lower nickel contents yield abundant NiFe and Ni sulfides. The dominance of metals over silicon results in the formation of crystalline silicates following metal saturation of immiscible Si-rich glasses. High gasification temperatures (1200 - 1500°C) promote the development of equilibrial assemblages. Chemical variations between individual feedstock cokes coupled with nonuniform operational conditions result in three principal categories of petroleum coke slag; 1) sulfide dominant, 2) silica dominant, and 3) oxide dominant. Sulfide dominant slags are not necessarily derived from feedstocks with high sulfur contents, instead they appear to derive from feedstocks rich in chalcophile elements, predominantly Fe and Ni, by attracting sulfur otherwise lost by volatilization. Slagging additives can change the chemical categorization of resulting slags through phase modifications and the formation of new phases; this in tum can strongly alter the physical behavior of the slags. Compositionally diverse spinel oxides are the most common crystalline slag phase because of their wide thermal and compositional stability ranges, refractory nature, and rapid growth kinetics. Spinel compositions are strongly influenced by the inorganic chemistry of the feedstock, the composition of host phases, and the composition of additives. Coke slag spinels are generally enriched in AI, Fe, V, Mg, and Ni, and often contain Cr that is derived from reaction with refractory material. / Ph. D.

Subcarrier multiplexing (SCM) on lightwave systems is an important technique for the near term implementation of broadband services by both telecommunication and cable TV companies. With advance in opto-electronics technology in the mid-1980s, lightwave SCM systems can now be practically implemented to provide a carrier platform for both digital and analog signals and (for short distance applications) are presently more cost effective than time division multiplexed systems. AM SCM systems are particularly attractive for multichannel video signal transmission due to their compatibility with the National Television Systems Committee Amplitude Modulated Vestigial Sideband (NTSC AM-VSB) TV format. However, AM SCM systems are generally recognized to have a limited system capacity due to large carrier-to-noise ratio (CNR) and low nonlinear distortion requirements. This research dissertation contains a comprehensive study of the system capacity of such systems based on theoretical analysis, experiment, and simulation. The practical performance of lightwave AM SCM systems are limited by the laser diode threshold-nonlinearity and laser relative intensity noise, the photodiode shot noise, and the receiver thermal noise. The practical system performance is evaluated and compared with that of the theoretical performance limit. The analysis indicates that AM SCM systems have sufficient system capacity for typical CATV loop distribution and supertrunking systems. It is shown that previous reported limits are generally overly conservative. A sensitivity analysis identifies the critical performance limiting parameters and provides system designers with achievable system performance as device characteristics improve. For 1550 nm AM SCM systems employing erbium-doped fiber amplifiers (EDFA) operating on the 1300 nm single-mode-fiber of telephone networks, there are additional sources of nonlinear distortion and noise to be considered. The nonlinear distortion produced by laser-chirp and fiber-induced-dispersion and the noise produced by the EDFA can significantly degrade the system performance. The analysis shows that the maximum link distance is limited by the composite-second-order (CSO) distortion, and the maximum number of subscribers is limited by the EDFA excess fluctuation noise. / Ph. D.

Stage of maturity at harvest and relative seed size can affect seed vigor. Greenhouse and field studies were conducted to determine the effect of seed maturity on seed vigor, storability, and subsequent plant growth of four cultivars of snap bean (Topcrop, Provider Black, Provider White, and Cherokee Wax). Seeds harvested between physiological maturity (PM) and harvest maturity (HM) showed the highest seed vigor and storability. At PM, seed moisture content was about 55%. A drop in seed fresh weight and a pod color change from green to yellow appear to signal the stage of PM. Delaying harvest past HM reduced seed vigor. The three cultivars with colored seed coats showed higher seed vigor than Provider White. Climatic and weathering effects on maturity, vigor, and yield of Topcrop and Cherokee Wax seed were evaluated at three locations (L-I, L-2, and L-3) in Sri Lanka having different agro-climatic conditions. Seeds that developed and matured under cooler conditions (L-l) produced higher yields and had larger size, better color, and higher vigor. Seeds developed and matured faster under warmer conditions (L-3); however, seed vigor and yields were lower and seed vigor dropped prior to HM. Cherokee Wax was the most tolerant to field weathering. Seeds of Topcrop and Cherokee Wax were separated by weight into three seed sizes (small, medium, and large) and evaluated for crop performance in two plantings (12/90 and 3/91). Field emergence was higher from larger seeds in the second planting, where the soil conditions were more stressful. Seedlings and plants at the flowering stage were larger and pod yields higher from larger seeds. The cultivar x seed size interaction was significant for pod yield per plant. Topcrop showed no differences, while with Cherokee Wax, pod yield per plant increased with increase in seed size during both plantings. Seeds produced from small seeds were similar or higher in vigor, indicating that small seeds could be used for seed production purposes. The data from these experiments indicate that vigor in snap bean seeds can be optimized by harvesting at an early stage after PM and by grading to remove small seeds. / Ph. D.

Land disposal of municipal wastewater is considered ecologically acceptable and cost effective. The success of land treatment systems, however, requires proper functioning of all ecosystem components. The impact of municipal wastewater irrigation on the structure and function of an Appalachian hardwood forest in Virginia was investigated. Four irrigation rates (17.5, 35, 70, and 140 em yr⁻¹ ) were applied in this hardwood forest, and their effects on forest nutrient cycling were monitored for two years. Tree growth, seedling reproduction, tree mortality, species diversity, and N sequestering by vegetation were not changed significantly. Herbaceous ground cover increased due to irrigation, except for the 140 cm yr⁻¹ treatment where the heavy spray caused physical damage to the cover. Depending on the rate applied, the mature hardwood forest system sequestered only -3.4 to 8.2 kg N ha yr⁻¹ in the above ground biomass. Therefore, the fate of added N to the system became a function of N transformation processes in the soil. Nitrogen mineralization and nitrification increased as irrigation increased. Denitrification rates were not affected by irrigation; the process of denitrification did not constitute a significant N output from the forest system. The additional soil nitrate (N0₃) was left to leach because of the low assimilation by the plant/soil system and the low denitrification rate. Nitrogen storage decreased in the forest floor due to the increase in litter decomposition, and increased in the surface soil due to the increase in microbial N assimilation. Total soil N increased on the low irrigation sites and decreased on the high irrigation sites, indicating that high rates of irrigation stimulated N loss from the soil by enhancing soil N transformations. The health of the forest ecosystem was not adversely affected during this period, but the forest did not serve as a net sink for N. There was little opportunity for N sequestering in this mature hardwood forest. Without harvesting and regeneration, the system is likely to lose system N when wastewater is applied. When wastewater is applied to lands, N sequestering and denitrification should be maximized in order to minimize the pollution potential of N0₃ leaching to groundwater systems. / Ph. D.

This dissertation is concerned with the position and vibration control of flexible articulated space robots consisting of a rigid platform, two flexible arms, and a rigid end-effector carrying a payload, all components being serially connected through revolute joints. The mission is to carry a payload over a prescribed trajectory in the inertial space, while suppressing the elastic vibration of the arms and the rigid-body perturbations. The equations of motion governing the robot dynamics are derived by means of Lagrangian mechanics and they include actuator dynamics. Based on the assumption that the elastic deformations and the rigid-body perturbations are small relative to the nominal trajectory-following rigid-body motions, a perturbation approach is adopted to separate the equations into nonlinear rigid-body equations and linear perturbation equations. The nominal trajectory is planned to conserve the limited actuator resources and keep the platform attitude stationary, by eliminating the inherent kinematic redundancy of the manipulator. By assuming perfect sensing, i.e., all the states are completely accessible, two kinds of controls are designed in discrete-time. First, a feedforward control is designed to minimize the persistent disturbance resulting from the nominal motions. Next, a feedback control is synthesized based on the Linear Quadratic Regulator (LQR) theory with a prescribed degree of stability to make the system stable and further enhance the disturbance-rejection performances. These controls are subsequently applied to the case in which only the sensor outputs are available, and they are noisy. A finite number of sensors is assumed. A Kalman filter is designed to estimate the state on the assumption of zeromean Gaussian white plant and measurement noise. In the real situation, controls are applied to the original plant rather than the linearized model, so that the Linear Quadratic Gaussian (LQG) control combined with robustness recovery methods is tested on the plant. Due to difficulties in implementing a Kalman filter, a Maximum Likelihood Estimator (MLE) is proposed. A numerical example illustrates the approach. / Ph. D.

Techniques for shear property measurements for composite and isotropic materials were investigated. A new strain gage called the shear gage was conceived, designed, and tested for routine shear characterization on notched shear specimens. The shear gage integrates the shear strain in the entire test section of the losipescu and compact shear specimens. The result was consistent and accurate determination of the shear stress/strain response of materials. Prior knowledge of material properties or shear strain distributions were not required. Deficiencies in the losipescu shear test were automatically compensated when shear gages were placed on the two faces of the specimen. The shear gages were tested on composite and isotropic materials and produced higher accuracy and consistency than could be produced using current technology. Moir© interferometry was used to evaluate the ability of the shear gage to measure the average shear strains. The results from the evaluation program confirmed the attributes of the concept. / Ph. D.