The teacher dismissal process is of critical importance to educators involved in both administrative and teaching positions. The legal prerequisites, opinions, and cases have been frequently reviewed and presented in countless studies. This study was designed to examine the dismissal process from the perspective(s) of the participants involved in the procedure. The study investigated the question: Do commonalities exist surrounding the circumstances and personalities involved in teacher dismissal proceedings during the school years 1987-88, 1988-89, or 1989-90? The study consists of ten field studies randomly selected from Virginia school divisions indicating a teacher dismissal during the period school years 1987-90. Field interviews were conducted to develop each of the ten case studies. The data were analyzed in two ways. First, like job participants were compared across case studies to identify commonalities during their involvement in the teacher dismissal process. Secondly, a profile of these commonalities was developed to show a typical pattern of circumstances and personalities involved in the teacher dismissal process. The study revealed that eight of the ten cases were based on issues outside of classroom instructional problems. Six of the ten teachers facing dismissal were ethnic minorities. Nine of the ten superintendents and all ten of the principals in the study did not hire the teacher facing dismissal in the cases. Finally, none of the teachers facing dismissal in the case studies was an active participant in a plan for improvement or a work plan. / Ed. D.

The precombustion desulfurization of coal was investigated by photochemical methods and by the application of a novel pyrite depressant in froth flotation. Semiconductor photoelectrochemical catalysis was extensively examined. As much as 41% of the organic sulfur was removed and 72% overall desulfurization of micronized Illinois No. 2 coal was obtained. Zinc oxide, in colloidal suspension, produced a small increase in the overall desulfurization at longer reaction times when compared to direct photolysis. The major limiting factor in organic sulfur removal from coal appears to be accessibility rather than reactivity. Kinetic experiments conducted with the model organosulfur compound, dibenzothiophene, showed high photochemical reactivity with nearly complete conversion occurring in 5 minutes in a saturated solution at 25°C. Scanning electron microscopic examination of product coals showed empty casts in places once occupied by iron pyrite. Additionally, a novel process was developed for separating clean coal from metal sulfide minerals such as pyrite and marcasite. The process comprises depressing the metal sulfide minerals with a reagent resulting from the alkaline oxidation and polymerization of a polyphenol or a quinone, and selectively floating clean coal from the depressed metal sulfide minerals. The process was investigated using microflotation, conventional Denver cell flotation, and microbubble column flotation. Up to 90% pyritic sulfur rejection was achieved from a coal and coal pyrite synthetic mixture. The process efficiency is a function of pH with greater improvements generally occurring at acidic pH when compared with the results obtained in the absence of the quinonoid reagent. However, in the case of microbubble column flotation with micronized coals, the largest overall pyritic sulfur and ash rejection occurred under alkaline conditions. Data from x-ray photoelectron spectroscopy and calorimetry indicate the quinonoid reagent modified the surface properties of minerals by reversible adsorption. / Ph. D.

The range of polymeric materials containing the Si-O bond spans from the three-dimensional inorganic networks of silica (SiO₂), to linear high molecular weight polysiloxanes which display properties of both organic and inorganic materials. Part 1 of this dissertation describes the synthesis of three-dimensional inorganic SiO₂ networks and organic-inorganic hybrid networks using a low temperature solution technique known as the sol-gel process. During this process, hydrolysis and subsequent condensation of inorganic alkoxides (most often tetraethylorthosilicate, TEOS) in the presence of catalysts leads to the formation of three-dimensional SiO₂ networks. However, the strong acid or base catalysts typically employed in sol-gel reactions would also cause undesirable degradation of many organic modifiers, especially at higher temperatures required for the drying of the gels. A catalyst-free sol-gel process, based on tetramethyl orthosilicate (TMOS), the most reactive silicon tetra alkoxide in the series, was developed. The catalyst-free route provides an optimum reaction environment for the synthesis of organic-inorganic materials through copolymerization reactions. This concept will be exemplified by two organic-inorganic systems in which TMOS was used as the inorganic component while poly(dimethylsiloxane) and polyimide oligomers respectively, were employed as the organic component. The effect of such modifications on the surface and bulk properties of the inorganic SiO₂ networks was also investigated. Part 2 of this dissertation describes specific aspects associated with the synthesis of amine containing polysiloxane oligomers. A new molecular design which allows for independent control of molecular weight and amine functionalities was developed. The new synthesis involves anionic ring opening equilibrium copolymerization of the cyclic siloxane tetramer D₄ with a new cyclic siloxane monomer containing amine functionalities as pendant groups on silicon atoms. The effect of the bulky substituent {-CH₂CH(CH₃)CH₂NHCH₂CH₂NH₂} of the silicon atom on the position of thermodynamic equilibrium, and the extent of molecular weight and composition control in the linear polysiloxane oligomers was studied. / Ph. D.

Mating success and nutrient reserve effects on queen survival and nest initiation were examined with respect to the reproductive fitness of queens of the baldfaced hornet, Dolichovespula maculata. The sperm content of the Spermatheca was examined in queens of this hornet species and in queens of 10 other yellowjacket species collected in spring and summer of 1987, 1988 and 1989. Queens of the baldfaced hornet, D. maculata, were also analyzed for sperm content prior to nest initiation and during colony development. A regression model was employed to determine sperm utilization. Based on total cell counts and adult census, the sperm use efficiency of this species changed from approximately 90-100 sperm released per egg in the initial stages of colony development, to 2-3 sperm released per egg after 1000 eggs had been laid. Near the end of the season the predicted number of sperm released per egg was 0-1. The number of sperm in D. maculata males ranged from 2-2.5 million; a value considerably greater than the mean sperm number (20,223; ±4,669) found in mated spring queens (n=15). Nineteen (18.4%) of 103 yellowjacket queens analyzed in the spring seasons of 1987 and 1988 were uninseminated. The effects of mating success and sperm utilization on colony development are discussed. A significant regression of sperm content on colony size was also found for 8 species of yellowjacket. Queens of D. maculata were collected for studies of nutrient reserves before hibernation in the fall, during nest initiation, and after colonies had produced more than 2 worker broods. Fresh and dry weights were determined for all queens and a seasonal comparison of the energy reserves of lipids, sugar, and glycogen was performed on the thoracic and abdominal tagmata. Total nitrogen was also quantified to estimate protein changes by season. The results show that lipids accounted for 35% of the weight lost during hibernation, sugars 12%, and glycogen 6%. Total thoracic nitrogen remained constant throughout the year, whereas abdominal nitrogen was the same in the fall and spring queens but increased in the summer queens. The results from this study suggest that most queens which survive the winter and successfully initiate nests have similar energy reserve quantities. The implications of these findings to solitary foraging behavior are discussed. The eggs of D. maculata were examined in the spring and summer to quantify the energetic contributions provided by the queen. Mean egg weight was highest in the spring and decreased with progressive nest development. Both egg weight and energy reserves were variable among and within nests. The nutrient reserves for eggs in embryo nests, in order of importance, were lipid (22%), glucose (9.5%), and glycogen (5%). A 10-day egg incubation experiment demonstrated a mean loss of 83 ug dry weight; lipids could not completely account for the weight loss, either quantitatively or qualitatively. A study on egg developmental time failed to provide sufficient data; all eggs eventually died although embryonic larval movement was detected in 2 eggs after 16 days. The energetic contributions which a queen provides to the eggs are discussed with respect to foraging behavior and environmental influences. / Ph. D.

This research is about technology transfer from engineering to management. According to Kerlinger’s (1979) terminology, most practical management problems are formulated as engineering problems. So, it is legitimate to adapt general engineering techniques to solve those problems. In Industrial Dynamics, Forrester (1961) says “the practice of medicine or of engineering began as an empirical art representing only the exercise of judgment based on experience. The development of the underlying sciences was motivated by the need to understand better the foundation on which the art is rested.” Engineering evolved from an art after practitioners applied relationships explained by basic laws of nature. Engineers design and predict the performance of the systems they work with. At most, managers hope for acceptable performance; management is still much an art, whose practitioners study relationships based on data and observation. Therefore, the objective of this research is twofold: to establish the groundwork for a discipline of management systems engineering, and to provide one example of its application. A management system is any organizational position, its scope of authority, and its management tools. The Management System Model (MSM) describes a management system as the interaction between the manager, the operation, and the management tools (Kurstedt, Mendes, & Lee, 1988). Management systems engineering involves the specification, design, implementation and maintenance of management systems. The specification of a management system identifies the required performance characteristics in response to given events. The design is the prediction, with the aid of mathematical models, of the actual responses (outputs) to those events (inputs). The conceptual part of this research involves the development of mathematical models as fundamental tools to specify and design engineering systems. One significant contribution is the development of the conceptual framework and the demonstration of a quantitative analog for the MSM. The applied part of this research draws upon an emergency exercise in an industrial plant (the United States Department of Energy’s Feed Materials Production Center at Fernald, Ohio). An emergency is any event that threatens the integrity of people, environment, or assets. In the context of this research, emergency response is the set of actions required to neutralize or reduce the effects of the threatening event. An emergency exercise is the live simulation of the response to a dangerous situation in an industrial setting. The management system is composed of the plant management, the industrial plant where a simulated accident occurs, and the management tools used during the emergency. Specifically, the objective of the applied part is to show we can use a mathematical model to describe the dynamics of the emergency management system and make short-term predictions. The mathematical model is a control theory-based system estimator. The data to compare the model against is time series data generated from information portrayed to the plant management during the unfolding of the exercise. Therefore, this research describes a longitudinal study. The similarity between the data and the model results is apparent in graphical representations and statistically demonstrated through spectral cross-correlation analysis. So, another significant contribution is revitalizing the formal application of control theory to the study of management situations. / Ph. D.

The advantages and disadvantages of packed capillary columns for high performance liquid chromatography are examined. Historically, the advantages are smaller sample and phase consumption, enhancement in sensitivity, easy column synthesis, higher obtainable efficiency, and easier interfacing to other techniques. These points are explored through experiments in microbore ion chromatography, packed fused silica columns, and capillary zone electrophoresis. These studies also address the disadvantages of microscale HPLC which are stringent instrument design, brittle or weak columns, poor column stability, and the lack of commercial instrumentation. The results of these investigations indicate the following. First, the purported sensitivity enhancement is really attributable to solute focusing and not to column miniaturization. Second, column synthesis is still a difficult procedure that requires experience. Third, higher efficiencies are realized, especially when the column diameter to particle diameter ratio is optimized. Fourth, interfacing to other techniques is simplified because of the lower volumetric flow rates. Finally, the only real disadvantages are stringent instrument design and brittle columns in some instances. This thesis offers means for circumventing these difficulties. / Ph. D.

Two new methods for coding image sequences in video conferencing systems are developed in this dissertation. A simple 3-D gradient operator is developed to estimate motion in an image sequence on a pixel-by-pixel basis. A stochastic 3-D gradient operator is also developed for a gradient calculation which is more robust to the noise effects of the image sequence. These gradient operators are used to estimate motion in the next frame using information from three previous frames. The concept of tangent plane, which is perpendicular to the gradient vector, is introduced to guide searching for the motion vector. The simplified 3-d gradient motion estimation (GME) technique is compared to Netravali's pixel-recursive method with scalar quantization. It was found that performance of the GME technique is very close to that of Netravali' s technique with less computational complexity. To adapt the motion estimation techniques to vector quantization, two new supplementary methods of motion estimation using the pixel motion vectors from the motion estimator were studied. The methods use either the pixel motion vectors directly on the moving block (pixel motion estimation) or calculate the block motion vector from the pixel motion vectors (block motion estimation). For both methods, the differences between the prediction block and the moving block are vector quantized. / Ph. D.

E. coli 0157:H7 is an important foodborne pathogen, responsible for several outbreaks of hemorrhagic colitis where improperly cooked hamburger meat was thought to be the vehicle. Various time/temperature combinations were used to determine the optimum conditions of heat shock which would result in the greatest number of survivors to a 55°C heat treatment. The optimum conditions were 42°C for 5 minutes and were used throughout the study. Heat shock of aerobically grown cells resulted in an increase in the mean D value after a 55°C heat treatment by a factor of 2.1 over nonheat-shocked controls. Heat shock of anaerobically grown cells also resulted ina significant increase in mean D value over nonheat-shocked controls. Anaerobic growth itself resulted in an increase in the ability of the cells to survive the 55°C heat treatment when compared with aerobically grown cells. Both heat-shocked and anaerobically grown cells contained a protein corresponding to a sigma³² subunit of RNA polymerase which has been identified as the 71,000 Galton heat shock protein characteristic of E. coli cells. Anaerobic plating resulted in a significant increase in the mean D values of both aerobically grown and anaerobically grown cells. The largest increase in mean D values was observed in aerobically grown non-heat-shocked cells, which increased by a factor of 2.3 when plated anaerobically instead of aerobically. The activities of catalase and superoxide dismutase in aerobically grown and anaerobically grown cells were studied to determine the reason why anaerobic plating enhanced recovery of cells. The activities of both enzymes were eliminated after heat treatment at 55°C for 20 minutes, regardless of whether the cells were heat-shocked or not. The ability of heat shock and anaerobic growth to protect the cells from a subsequent heat treatment was tested by measuring the rate of release of cell materials during heating at 55°C. Heat-shocking and anaerobic growth resulted in even faster release of cell materials during heating than controls, suggesting that neither of these stresses protected the cells against the effects of heat. The effect of heat shock on cell injury was studied. Heat shock of aerobically grown cells resulted in the greatest difference in log number of cells between cells plated in nonselective medium vs. selective medium. Thus, more cells were injured if heat-shocked than if not heat-shocked. Heat-shocking of anaerobically grown cells also resulted in more injured cells than non-heat-shocked controls. / Ph. D.

The study of focal shift in focused beams using unapodized apertures has been well documented. However, not much work has been done on apodized apertures. In this thesis we use a Fourier-Optic approach to analyze the field distribution of a focused beam around the region of geometrical focus. The analytical formulation developed is general in nature as it is valid for any arbitrary aperture functions. This is then applied to some specific cases. Two cases of interest that are considered are the unapodized and the Gaussian apodized annular apertures. In order to study the intensity distributions around the geometrical focus, simulation results are presented using closed form analytical expressions and approximate integral forms. Specific emphasis is placed on the focal shift in the two apertures and on the effect of changing various parameters. A prognosis for future work using a-Modulation on Gaussian apodized annular apertures is also presented. / Master of Science

This thesis summarizes the results of an experimental study on transonic turbine blades in the presence of ejection of coolant in the direction of the flow from slots near the trailing edge. I t presents the effect of the trailing edge coolant ejection on the turbine blade aerodynamic efficiency.¹ The objective of this work is to contribute to the design of new turbine blades by giving loss data for cooled blades. Data were taken in the Virginia Polytechnic Institute & State University wind tunnel, which includes a two-dimensional transonic turbine cascade. The tunnel simulates supersonic discharge flows of turbine rotor blading in a linear cascade with trailing edges designed for ejection of cooling flow. Two blade designs, named Baseline and ULTRE, were tested. Experiments were performed on a transonic turbine cascade designed for a deflection of approximately 68 degrees and outlet Mach number of 1.14 for the Baseline blade and 1.2 for the ULTRE blade. Tests were carried out with CO₂ as coolant in order to ensure the proper simulation of the density ratio between coolant flow and main flow. Data were obtained for both the Baseline and ULTRE cascades with a good periodicity. The content of this thesis is limited to the aerodynamic aspects of coolant ejection. Heat transfer aspects are mentioned but not developed. The first part of this thesis reports on the theoretical considerations necessary for the understanding of the work done and describes the arrangement, instrumentation, and data acquisition system of the wind tunneL The second part of the thesis presents experimental results from tests carried out on both Baseline and ULTRE blades. The cascade tests cover an exit isentropic Mach number range of M2,it = 0.72 to 1.34 and four different ejection rates. 1 The efficiency being characterized by the total pressure loss in this work / Master of Science