There is a critical need for materials with very high dielectric constant to be integrated in the next generation of 64- and 256-Mb ULSI DRAMs. Materials in the Pb-based perovskite family have high relative permittivities and have consequently attracted a world wide attention. Cubic Lead Lanthanum Titanate (PLT) is one of the prime candidates in this respect and its structure and properties in the thin film form were investigated in the present study, for potential application in the ULSI DRAMs. Thin films of Lead Lanthanum Titanate corresponding to 28 atomic percentage of lanthanum were prepared by metalorganic decomposition (MOD) process. Solutions were prepared from lead acetate, lanthanum acetate and titanium iso-propoxide and thin films were then spin-coated from these solutions on PtlTilSi0₂/Si and sapphire substrates. The films were fabricated from two solutions of different compositions. The composition of the first solution was determined assuming that the incorporation of La³⁺ in the PbTi0₃ structure gives rise to A-site or Pb vacancies whereas for the composition of the other solution the creation of B-site or Ti vacancies was assumed. The effect of excess lead on the structure and the properties was also studied for 0% to 20% of excess PbO. The x-ray diffraction patterns of all films at room temperature indicated a cubic structure with lattice constant of 3.92 A. Optical and electrical measurements showed that the films made assuming B-site vacancies had better properties. In general, excess PbO was found to improve the optical as well as the electrical properties of films. However, in films with Bsite vacancies this improvement occurred only up to 5-10% of excess PbO, while higher PbO additions had a deleterious effect. The films had high resistivity, good relative permittivity, low loss, very low leakage current density, and high charge storage density. A type-B film with 10 % excess Pb had a permittivity of 1336 at 100 kHz. It also had a charge storage density at room temperature of around 16.1 μC/cm² at a field of 200 kV/cm and no sign of polarization loss or breakdown was observed up to 10¹⁰ cycles under the accelerated degradation breakdown test. / Master of Science

The response of foals to the stress of weaning was examined in terms of a behavioral protocol and the responses of plasma ascorbate, serun1 cortisol, and the serum cortisol response to an ACTH challenge. Behavior scores (1 to 10) as an index of stress were assigned to each foal daily, with high scores indicating less stress and better adjustment. The experimental plan was a 2 X 2 factorial of pre-weaning diet and stall weaning method. Foals were raised on pasture supplemented with hay and a pelleted concentrate (PHC) or pasture supplemented with hay only (PH). Foals were placed in stalls singly or in pairs for weaning. Gender influences were also examined. The foals exhibited characteristic behavioral and physiological responses to the social dislocative stress of weaning. Behavior scores were lower in paired than in single foals (p = .008) and tended to be lower in PH than PHC foals (p = .15). No differences in post-weaning plasma ascorbate concentrations were found among treatments. Responses of serum cortisol to an ACTH challenge were lower in PH than PHC foals (p = .001) and in paired than single foals (p = .058), and lower responses were taken to represent adrenal depletion arising from stress. Behavior scores were positively correlated with the response of serum cortisol to ACTH. Both behavioral data and the serum cortisol response to ACTH indicate that foals were better able to cope with weaning stress when supplemented with concentrate prior to weaning and when weaned singly. / Master of Science

Bioindicators were used to assess degradation to fish resident to the Clinch River drainage. Species studied were rock bass (<i>Ambloplites rupestris</i>), northern hogsucker (<i>Hypentelium nigricans</i>) and striped shiner (<i>Luxilus chrysocephalus</i>). The data were collected in parallel with a study of the index of biotic integrity (IBI) on fish communities also in the Clinch River drainage. Sites selected for this study were identical to those used for IBI. Data obtained from fish sampled at relatively pristine sites (i.e., high IBI) were used as references to be compared with data obtained from fish sampled at sites suspected of human impact (low IBI). Results demonstrated variable bioindicator response to degraded sites. While bioindicators were elevated at certain sites, others were not significantly different from corresponding reference values. Furthermore, results showed a number of correlations between certain bioindicators and IBI and several IBI components, implying a possible relationship between these initial individual-level responses (biondicators) and eventual longer term population- and community-level effects (i.e., IBI and its components). However, these results also varied between impacted sites. Future field application of bioindicators in the presence of such a multiplicity of potential stressors was discussed. / Master of Science

Most work in knowledge acquisition and manipulation has focused on expert systems. Expert systems solve one kind of problem: heuristic classification. This thesis extends some advances in knowledge engineering to a broader class of problem: design. Design is examined as a generic activity, found in many fields of professional practice. A theoretical framework is developed that supports the refinement of design from high-level concepts through implementation. This framework includes a computational model that is shown to be completely general (Turing-equivalent). Therefore, the theory and model are suitable for representing any design project. They are applied specifically to software development. Practical support for software designers is offered in a prototype software design system. Existing work in automated knowledge acquisition is used to transfer knowledge about a design from the designer to the automated tool. Consistent support for refinement of design choices at any level of detail makes design a maintainable activity. This opens new possibilities for automated code generation, automated maintenance, and the nlore effective management of software at a higher-level design representation. / Master of Science

The study of human-environment interactions by geography is traditionally conceptualized as the "man-land" theme in geographic analysis. Feminists and other post-structuralists criticize that conceptualization. Following those critiques, this study evaluates ecofeminism as a possible alternative to a "man-land" formulation. Ecofeminism is presented and analyzed as a school of thought that also studies human-environment interactions. Vandan Shiva's discourse and treatment of Chipko provide the central ecofeminist case study. The thesis elucidates ecofeminism's sensitivity to the geographic concept of place in order to determine whether or not ecofeminism is adequate as a geographic theory. Analysis of Vandana Shiva's texts reveals that ecofeminism universalizes and fails to accommodate the geographic concept of place. / Master of Science

The design, performance, and analysis of a soil vapor extraction system to identify zones most conductive to air transport and quantify kair in sequential soil layers is presented. A multi-level extraction well, with alternating solid and screened sections, was utilized to characterize multi-layered media. The field site, located in the Carolina Slate Belt within the physiographic region known as the Piedmont, is comprised of alternating layers of different soil types of varying kair, including thin bands of clay, silt, and sand. The pneumatic test consisted of one multi-level extraction well and four multi-level pressure monitoring wells. Screen locations were based on previous site characterization. Vapors were extracted at one screen while pressure, temperature, and volumetric flow rate were monitored using a computer data acquisition system. Data was analyzed by both steady-state and transient solution techniques using pressure drawdown versus time data collected at various locations. Results from vapor extraction tests indicate that the multi-level approach is advantageous when dealing with heterogenous media, since the most permeable layer was identified. Transient and steady-state solutions indicate that a k_air= 2.0 X 10⁻⁷ cm² is representative of the located permeable layer within the subsurface. Vacuum system, formation, and extraction well characteristics are evaluated to determine pressure as a function of volumetric flow rate. / Master of Science

Periodic gratings in waveguides act as frequency selective mirrors making them very useful as spectral filters for wavelength division multiplexing applications and as end mirrors for narrow linewidth lasers. A study of the spectral characteristics of both single and double gratings in planar dielectric waveguides is presented. The analysis of light propagation in a planar dielectric waveguide with sinusoidal boundary perturbations is carried out using coupled-mode theory. Power reflection and transmission coefficients are calculated for single gratings as well as two gratings of the same period and depth but arbitrary lengths and separated by a specified distance. The spectral response is examined for several cases. The influence of grating period, depth, and length in the single-grating case as well as separation of the gratings in the case of a double grating is investigated. Numerical results for example cases are presented. The results of this study are valuable for designing grating devices which are becoming increasingly attractive to broadband fiber-optic communication systems. / Master of Science

A micro mechanical finite element model to compute the overall instantaneous stiffness of fiber-reinforced composites in elastic-plastic response is presented. The model is applicable to a periodic diamond array of elastic circular fibers embedded in an elastoplastic matrix subjected to a plane stress loading. This model enforces symmetry and anti-symmetry conditions isolating the smallest unit cell and should greatly increase the speed of doing "built-inn micromechanics within a larger finite element program because of the small number of degrees of freedom (12 to 14 d.o.f.). The matrix plastic behavior is modeled using the endochronic theory without a yield surface. Various off-axis elastoplastic characteristics predicted by the mini grid for a boron/aluminum composite are presented. Comparison with experimental data and a fine grid finite element solution shows very good agreement and demonstrates the effectiveness of the mini model presented. / Master of Science

Performance of three carbohydrate-based fat replacers (pectin, gum, and oat fiber) in a southern-style baking powder biscuit was evaluated at substituted levels of 33%, 66%, and 100%. Objectives and sensory tests were conducted on all samples. Results were compared to the control for the determination of significant differences at (p<0.05). Overall objective test results suggested that there was an increase in the degree of expansion as the level of fat replacement increased. Significantly (p<0.05) softer crusts and crumbs were observed with the fat replaced variations. All fat-substituted biscuits had significantly (p<0.05) higher moisture contents. Upon 24 and 48 hours of storage, staling was observed in all variations with the 100% variations having the most staling. There was a significant (p<0.05) caloric reduction as the level of fat replacement increased. However, this was an over-estimation of the calories provided upon human utilization. Also, the Land and b values of the crust color significantly (p<0.05) decreased with fat sUbstitution. The QDA results indicated that the panelists observed the degree of browning, cell size, dryness, and tenderness significantly (p<0.05) decreased whereas, perceived cohesiveness significantly (p<0.05) increased as the level of fat replacement increased. Bitterness also increased as the fat replacement level increased. The general population with an Appalachian influence "moderately liked" the control and oat-based 33% and 66% variations which were selected on the basis of the QDA results. Overall, the fat substituted variations with the most desirable characteristics were the pectin and oat-based 33% biscuits. The 100% variations would be the most beneficial in caloric reduction, however, their attributes would not be representative of an "ideal" Southern-style baking powder biscuit. / Master of Science

A novel in-situ stress measurement technique to study the formation kinetics of multi component oxide thin films was developed and was applied to PbTiO₃. Single phase PbTi 0₃ thin films were formed from the reaction between films in the deposited PbO ITi0₂ multilayer. The film stoichiometry was accurately controlled by depositing individual layers of the required thickness. Development of film stresses associated with the formation of the product layer at the PbO/Ti0₂ interface of the multilayers was used to monitor growth rate of the PbTiO₃ layer. It was found that growth of the PbTiO₃ phase obeyed the parabolic law and the effective activation energy was estimated to be 108 kJ/mole. It is believed that the mechanism of this reaction was dominated by grain boundary diffusion of the participating cations. / Ph. D.