A severely defocused incoherent system has isolated zeros in its optical transfer function(OTF); therefore, an exact inverse filtering cannot be performed. It has been established that, by using an annular aperture in an optical system, the depth of focus can be extended. Isolated zeros in the OTF can therefore be avoided by choosing an annular aperture with a proper radius ratio. However, in the process of increasing the depth of focus of the system, this method results in a loss of image contrast. An annular pass filter can be used to restore this loss in contrast. A simple hybrid optical/digital image processing system in which a TV camera is coupled with an annular aperture is considered. The annular-pass filtering to compensate for the loss of contrast is performed by a digital computer. The experimental results are presented. / M.S.

The rapid proliferation of microprocessor based products has increased the need of Microcomputer Development Systems. The IBM PC's software architecture is modified to make it an Intel Series III compatible development system. Universal development interface (UDI) is used to allow all Intel languages and object modules to execute on the IBM PC. The development languages available are the 8086/8088 assembly language, with F0RTRAN-86 and Pascal-86 as the high level languages. The exact working and operating procedures of the software development tools, like an assembler, compiler, linker, locater, hex to object converter and a debugger are explained in detail. Mathematical support is either through an 8087 or its emulator. Detailed explanation of high level language program execution is given, including the run time support needed. A serial loader program is also available to downline load programs from the IBM PC development system to other target machines, like the SDK-86 single board computer. / M.S.

Catalase and superoxide dismutase, but not peroxidase activity was detected in cell-free extracts of Mycobacterium avium, M. intracellulare and M. scrofulaceum (MAIS). The M. scrofulaceum isolates had the highest catalase activity, while both M. avium and M. intracellulare had significantly lower activities. The percentage of catalase activity remaining, after exposing cell-free extracts from late log grown cells to 53°C for 50 minutes allowed differentiation among all three species. Polyacrylamide gel electrophoresis of crude extracts demonstrated two bands of catalase activity in both M. avium and M. intracellulare extracts and four bands of activity in M. scrofulaceum extracts. These bands differed in their susceptibility to heat inactivation and inhibition by 3-amino-1,2,4-triazole. M. scrofulaceum strains, but not M. avium and M. intracellulare, demonstrated extracellular catalase activity. The susceptibility to H₂O₂ of 6 M. avium strains, differing in catalase activity and cell permeability, were tested. At a concentration of 0.02% H₂O₂, all M. avium strains were resistant, while differences in susceptibility were seen at 0.08% H₂O₂. Strains of low extract catalase activity and high H₂O₂ permeability were most susceptible. The superoxide dismutase activities of the MAIS strains tested were similar and no species-specific differences could be discerned. Electrophoresis of crude extracts demonstrated a single band of activity for each of the MAIS strains. Extracellular superoxide dismutase activity was detected in four of six MAIS strains. The metal type of MAIS superoxide dismutase was indirectly determined by inactivation with KCN, NaN₃ and H₂O₂. / M.S.

In this thesis, a stochastic model was utilized to predict the water content and sediment deposition characteristics in the Mazar Reservoir in Ecuador. The results obtained were compared with those reported in the project's feasibility study. The methodology used in this study was based on the assumption that annual water inflow can be taken as a random variable and annual water contents in the reservoir form an independent series of first-order, homogeneous Markov Chains. The available stream flow records indicated that normal and log-normal probability distributions would adequately characterize the annual water inflows. Using Moran's storage theory, expected values of the reservoir water contents were calculated for consecutive years until the storage probability transition matrix operation yielded a stationary condition. Annual amounts of sediment deposition in the reservoir were determined as the difference between annual sediment inflows and outflows. Two different scenarios were applied to calculate the annual sediment inflows. In the first scenario, based on the deterministic sediment rating equations, the resulting sediment rates were assigned the same probabilities as the water inflows. In the second scenario, the annual sediment rates were also considered as random variables normally distributed around the mean values. The results obtained indicated that a stochastic model, such as the one employed in this study, can be effectively used to predict sediment deposition in a reservoir to complement the predictions obtained with deterministic methods, and can even yield a more reliable spectrum of results that can be associated with various confidence levels, particularly when the data on actual sediment measurements is scarce. / M.S.

The research was performed to determine factors associated with weight loss maintenance. Factors examined included: a) physical characteristics, b) eating habits, c) self-motivation level and d) activity level. Subjects included 19 overweight females who had participated in a nutrition and exercise program held at Virginia Polytechnic Institute and State University. Two separate groups of subjects were contacted and interviewed. Group 1 (n=11) participants in a six week treatment program, consisting of a very low calorie (530 kcal) liquid diet, and a supervised exercise program corresponding to 60% VO₂ max for 30-40 min., 3 times/week. Group 2 ( n=8) consisted of an eight week treatment program, consisting of mild caloric restriction (1200-1500 kcal/day), and a supervised exercise program corresponding to 70% VO₂max for 30-40 min. Group 1 was 12 months post formal treatment and group 2 6 months. A questionnaire was developed and administered to the subjects. The first three sections were multiple choice concentrating on eating habits, behavior modification techniques, and self-motivation level (SMI). The last section was an interview session ascertaining information on activity levels. Of the factors examined, four were found to be prevalent for both groups: skipping breakfast and a strong appetite in the evening showed higher average weight gains, preplanning meals and higher self-motivation levels produced a lower average weight gain. Group 1 showed lower average weight gains for those individuals who joined another program and ate 3 meals a day. Group 2 showed individuals who had higher activity levels had lower average weight gains. Due to the low incidence of maintenance of weight loss, it appears necessary to emphasize maintenance strategies during treatment sessions. Also it appears necessary to individualize treatment for subjects due to the range of self-motivation levels. Booster sessions and/or continued treatment may be helpful for those exhibiting a low motivation trait. / M.S.

The investigation of structure-property behavior of extruded cast films prepared from blends of thermotropic liquid crystalline copolyesters with polyethylene terephthalate (PET). Data were obtained which showed not only the temperature dependence of the moduli and stress-strain behavior but also the orientation effects that must be prevalent in order to explain the differences between the moduli measured parallel and perpendicular to the extrusion direction. Only at high liquid crystal polymer (LCP) compositions is the modulus particularly increased. The modulus enhancement with lower LCP content and utilization of process variables are discussed. Specifically, the extruder gear pump speed did not enhance Young's modulus at the same LCP content as extensively as did the effect of extruder screw speed. Also a study to synthesize and characterize new segmented copolymers that could produce unusual film properties are discussed. The approach involved the synthesis of high Tg (220 C) isotropic poly (aryl ether sulfone) oligomers of varying segment molecular weights. The thermal and mechanical studies of the copolymers have been carried out to probe the potential of these copolymers for signs of liquid crystalline character and to note their ability to thermally crystallize as well as to crystallize by solvent or strain inducement. Along these lines, thermal analysis, polarizing hot-stage microscopy, wide angle x-ray scattering and mechanical testing were utilized in this investigation / Master of Science

The use of wilderness rangers to educate visitors on Without-A-Trace camping and wilderness ethics at trailheads is a common management practice, but little is known about how such contacts affect the visitors' wilderness experiences. The purpose of this study was to determine whether Shining Rock Wilderness visitors perceived trailhead contacts as light-handed or heavy-handed and the factors which caused them to perceive the contact the way they did. It also determined whether or not the visitors felt that site conditions in the wilderness were getting better or worse. On-site questionnaires were administered to visitors as they left the area. A majority felt the trailhead contact was a light-handed way to manage wilderness use. The visitors felt that the contact did not take away their freedom to choose how, when or where to recreate. The rangers were perceived as friendly, knowledgeable, and non-authoritarian. The condition of Shining Rock Wilderness was perceived to be relatively free of site impacts. There were no significant differences in the visitors' perceptions of the ranger or the contact due to the sex or experience of the ranger or the sex, age, or experience of the visitors. Implications for wilderness management and research are discussed. / M.S.

The problem examined is an infinite anisotropic layer with a through crack at arbitrary orientation, subjected to uniform in-plane remote loading. The purpose of this study is to gain a better understanding of several theoretical models for predicting the direction of crack propagation and the level of load causing crack extension, and to present a new model for predicting the critical load. The discussed models are particularly examined in detail with regard to the physical parameters affecting the results. Comparison is made with available experimental results. It is shown that the normal stress ratio theory provides good agreement with experimental crack growth direction, independent of physical parameters, and that the newly proposed traction ratio theory predicts well the critical load causing crack extension. / M.S.

There are algorithms for finding zeros or fixed points of nonlinear systems of (algebraic) equations that are globally convergent for almost all starting points, i.e., with probability one. The essence of all such algorithms is the construction of an appropriate homotopy map and then tracking some smooth curve in the zero set of this homotopy map. The augmented Jacobian matrix algorithm is part of the software package HOMPACK, and is based on an algorithm developed by W.C. Rheinboldt. The algorithm exists in two forms-one for dense Jacobian matrices, and the other for sparse Jacobian matrices. / M.S.

Findings of higher incidence of depression among females have spurred research examining differences in the etiology and maintenance of male and female depression. A variety of differences have been identified including behavioral, cognitive, and environmental responses. Recently, increasing attention has been directed toward the importance of social interactional factors in depression. However, this research has been contradictory and inconclusive. The purposes of the current investigation were to further explore social interactional factors using face-to-face interactions between depressed and nondepressed individuals and to explore the applicability of a social interactional model to observed differences in male and female depression. Depressed and nondepressed subjects were assigned to interact with same or opposite sex partners. The twenty minute interactions were videotaped and scored by a behavioral coding system. Subjects completed questionnaires concerning perceptions of their partner and the interaction. Results indicated that depressed and nondepressed subjects behaved similarly during the interactions. However, depression was associated with fewer initiations and more somatic complaints. Depressed subjects reported improved mood following interactions. No differences were found between males' and females' self-report of depression. However, males reported greater negative affect before and after interactions. Partner impressions differed based upon group placement. Females interacting with females were viewed most positively while males interacting with males were viewed most negatively. Sex, and not depression status, appeared to account for these differences. Implications are discussed in terms of support for behavioral and cognitive theories and alterations of the social interactional model. / M.S.