An atomic force microscope (AFM) was used to measure surface forces between a glass sphere and a flat fused silica plate under a number of conditions. Hydrophobic surfaces exhibiting contact angles ranging from 0 to 109° were prepared by reacting silica with octadecyltrichlorosilane (OTS). Contact angles, AFM images, and infrared transmission spectra showed that OTS forms clusters on the silica surface. The presence of water in the reaction was shown to greatly influence the formation of these clusters. Forces were measured between surfaces coated with identical (symmetric) and different (asymmetric) amounts of OTS to determine contributions from hydrophobic forces. The results showed that the hydrophobic force parameters of the asymmetric interactions, K132, can be predicted from those of the symmetric interactions, K131 and K232, using a geometric mean combining rule. Asymmetric force measurements were conducted between a hydrophobized glass sphere and a bare silica plate in dodecylamine hydrochloride (DARCl) solutions as a function of pH in an effort to simulate the forces involved in bubble-particle interactions for the quartz-amine flotation system. The appearance of the hydrophobic force in these measurements correlates well with the pH range of maximum flotation recoveries for quartz-amine flotation system. / Ph. D.

An efficient design formulation for feedforward Active Structural Acoustic Control (ASAC) systems for complex structures and disturbances is presented. The approach consists in a multi-level optimization procedure. The upper level part is carried out in the modal domain, where the optimum modal control forces and modal error sensor components which minimize the total radiated power are obtained. These optimum modal parameters are then used in a set of lower level optimization problems to find the physical characteristics of the actuators and sensors to be implemented. In this work, the developed formulations are demonstrated in three systems of increasing complexity. First, a simply supported plate excited by at a single frequency is presented. The study of this relatively simple case serves as a benchmark for more complex systems permitting the evaluation of the performance of the design approach. Then, the formulation is implemented for the case of a simply supported cylinder under multiple frequency excitations. In this case numerical techniques are used to obtain the structural and acoustic responses showing the capabilities of the formulations to be implemented to complex structures. In both cases (i.e., the simply supported plate and cylinder), the results show that the optimum configurations yield significant reductions in the total radiated acoustic power depending on the number of control channels and allowed control effort. Moreover, it is demonstrated that the proposed design approach gives a clear insight into the relative contributions of the modes to the sound field providing a better understanding of how they have to be controlled in order to minimize sound radiation. Finally, the design approach is validated in an experimental arrangement for the attenuation of sound radiation from and enclosed box structure under a realistic periodic disturbance. Up to 36dB of attenuation in the acoustic power is obtained in the experiment demonstrating the effectiveness of the proposed design approach for practical applications. / Ph. D.

A comprehensive study including modeling and control of aeroelastic instabilities in free flying aircraft with flexible wings has been completed. The structural model of the wing consists of a trapezoidal composite plate rigidly attached to a fuselage with rigid-body degrees of freedom. Both quasi-steady and quasi-static aerodynamic strip theories were used to analyze several different flutter mechanisms for a variety of low aspect ratio wing configurations. The most critical flutter mechanism was found to be body-freedom flutter, a coupling of aircraft pitching and wing bending motions, for wings in a forward-sweep configuration. In addition, a modal approximation to the flutter eigenvalue problem was used to substantially reduce computation cost, making the resulting model very attractive for use in larger multiobjective design packages. Composite ply angle tailoring was investigated as a passive method of increasing the body-freedom flutter airspeed of an aircraft model. In addition, wing mounted piezoelectric sensor and induced-strain actuator patches were used in conjunction with active feedback control laws to increase the airspeed at which body-freedom flutter occurs. Two control laws were tested, coupled and independent modal position feedback, to delay frequency coalescence and thus increase the flutter airspeed. / Ph. D.

The purpose of this study was to investigate how Virginia Polytechnic Institute and State University (VT, Virginia Tech or VPI&SU) had complied with Title IX from 1972-1992. The case study investigated the governing process of the institution’s progression of Title IX compliance. The study explored one prominent question: How had VT complied with Title IX from 1972-1992. Three subquestions relevant to the discussion of gender included: (a) How had VT performed in the three prong test of Title IX? (b) During the period 1972-1992, how did VT adhere to the compliance of the thirteen components of Title IX? and (c) What were the governing processes of VT towards Title IX in both written documentation and verbal interviews. The instrumentation of the study was two-fold. The first stratum was to review court cases that were relevant to Title IX. In reporting these cases, a "brief type" system was utilized. The brief of each case included the following: citation, topic, relief sought, issues, facts, finding of the trial, finding of the appellate court, reasoning, and significance. A case study methodology was used in researching VT Athletic Department compliance with Title IX. Documentation to support the Title IX case study included athletic department correspondence, Athletic Department Title IX studies, University related correspondence, and printed documentation. The outcome of the study revealed VT’s governing process towards Title IX during the twenty year period. The move towards compliance was based upon the philosophy of the athletic director as well as the president of the university. Prior to 1987 and the passage of the Civil Rights Restoration Act, VT athletics was a corporation and not a department within the university. Also, athletics was not held accountable for Title 1X compliance since athletics did not receive direct federal funding. After the passing of the Civil Rights Restoration Act, all departments were liable for Title IX compliance. In 1992, the VT athletic department was equitable in meeting the following thirteen components: interests and abilities, equipment and supplies, opportunity to receive and compensation of tutoring, housing and dining facilities, and recruitment of student athletes. / Ph. D.

The Occupational Stress Inventory (OSI) and an Individual Data Form (IDF) provided information about the levels of occupational stress, psychological strain, and coping resources for a random selection of 414 professional counselors licensed by the state of Virginia (LPC). The return rate was 77.3% (n=320), and the number of responses used for analysis was 258. The IDF provided a general description of the LPCs. Most of the respondents were white (n=248) and married (76%) and averaged 47.23 years old. There were 154 females and 104 males. The majority (72.5%) were parents and the mode for number of children was two (32.94%). The LPCs averaged 15 years experience and had been licensed an average of 8.86 years. The most often reported practice setting was private practice, either individual (20.5%) or with group affiliation (17.4%). The majority (91.7%) of the LPCs worked with clients and averaged doing so 4.2 days per week. The average number of daily client sessions was 4.78. The maximum number of client sessions per day averaged 7.45. Most of the clients (60.59%) were self-referred for counseling. Overall T-scores on the OSI were in the average range for stress, strain, and coping. Demographic variables found to be significant for levels of occupational stress included gender, primary work setting, weekly work hours, number of days per week clients were seen, average and maximum daily client sessions, and whether the clients were self- referred or legally mandated to attend counseling. Levels of psychological strain were significantly different depending on the LPCs' age, gender, marital status, primary work setting, and whether stress-related treatment had been sought. Primary work setting, number of days each week clients were seen, and whether the LPCs had sought stress-related treatment significantly influenced coping resources. Various subscales of the OSI were found to be significant for each of the domains of stress, strain, and coping depending upon the level of the demographic variables. The only variables found to have significance for levels of stress, strain, and coping was practice setting. Implications for the profession and recommendations for future research are made. / Ph. D.

The purpose of this study was to determine if a relationship existed between school board members' religious and political leanings and their attitudes on selected education issues in which members of the Christian Right are active. The research questions for this study were, (1) Do school board members perceive themselves as religiously conservative or liberal? (2) Do school board members perceive themselves as politically conservative or liberal? (3) What are school board members' attitudes on education issues dealing with separation of church and state and school choice? (4) Is there a relationship between school board members' perceived religious leanings and their attitudes on these education issues? (5) Is there a relationship between school board members' perceived political leanings and their attitudes on these education issues? Members of the Christian Right have identified several education issues in which they are active. These issues include separation of church and state and school choice. They are working in political arenas to define their positions and develop political and educational strategies to achieve those positions. Like other groups, members of the Christian Right are dissatisfied with the current condition of public education and the results of restructuring efforts of America's public schools. Descriptive research methodology was utilized in this study. A stratified, random sample of school board member subscribers to The American School Board Journal was identified, and subsequently surveyed through the use of a mailed survey. Sixteen percent of the population of 36, 619 were surveyed. A total of 6,135 surveys were mailed to subscribers of The American School Board Journal. The response rate for the questionnaires was 20.3% (1,247 of the 6,135 surveys were analyzed in this study). The data clearly show that the school board members who responded to the survey perceived themselves as religiously conservative and politically conservative. As a group, school board members did not necessarily reflect educational positions espoused by members of the Christian Right. For example, in the area of separation of church and state, less than one-third of the respondents agreed that America needed a constitutional amendment allowing prayer in public schools. In the area of school choice, almost two-thirds of the respondents agreed that school choice plans will widen economic and racial gaps between schools. However, when examining the responses which reflect the positions of the Christian Right pertaining to the identified education issues, those who perceived themselves as religious conservatives, and to a greater extent, those who perceived themselves as political conservatives, clearly reflected those positions. The data show that there is a relationship between a school board member's perceived religious leaning and their attitudes on the selected education issues, and there is a stronger relationship between a school board member's political leaning and their attitudes on the selected education issues. / Ed. D.

African trypanosomiasis is one of the most important hemoprotozoan diseases affecting both humans and livestock in sub-Saharan Africa. A blunted erythropoietin (Epo) response has been proposed as one possible mechanism that contributes to the nonresponsive anemia in trypanosome-infected cattle. The overall objective of this study was to examine the pathophysiologic role of Epo in the anemia associated with Trypanosoma congolense infection in cattle at the molecular and cellular levels. Bovine Epo cDNA from N’Dama cattle (Bos taurus) and Boran cattle (Bos indicus) was isolated by polymerase chain reaction (PCR) amplification and by screening of a bovine kidney cDNA library. Using in situ hybridization, Epo mRNA was detected in interstitial fibroblast-like cells in the kidney of an anemic calf (created by phlebotomy). Epo mRNA was also detected in the spleen from the anemic calf and the spleen of a 19 week old bovine fetus using quantitative PCR assay. The bovine Epo cDNA was expressed in three different expression systems: bacterial, vaccinia virus (VV), and Chinese Hamster Ovary (CHO) cells. The recombinant bovine Epo (rbovEpo) expressed in CHO cells was more biologically active than that expressed in the other systems. The purified rbovEpo was used to develop a hybridoma secreting high affinity monoclonal antibodies to rbovEpo. Competitive reverse transcription and the PCR (RT/PCR) were used to compare the concentrations of Epo mRNA in the kidney during chronic and acute infection with T. congolense in trypanotolerant (N’Dama) and trypanosusceptible (Boran) cattle. The Boran cattle were more anemic, with packed cell volumes (PCV) ranging between 14-21% while N'Dama cattle had PCV values between 19-36%. Surprisingly, the increases in Epo mRNA did not vary significantly in the kidneys from the two breeds. However, the amount of Epo receptor transcripts in bone marrow during acute infection of N’Damas was significantly (P <0.05) higher than that detected in the marrows of Borans. These findings suggest that Boran cattle are incapable of eliciting an appropriate Epo response for their degree of anemia. Negative regulators of Epo gene expression, such as IL-1α and β, TNFα and IFNγ were expressed in the kidneys from chronically infected Boran cattle at significantly (p < 0.05) higher concentration than in the kidneys from chronically infected N’Dama cattle. Furthermore, during acute infection with 7. congolense the concentration of IFNγ mRNA in the kidney from Borans was significantly higher - as were the mRNAs of IL1α and β, and IFNγ - in the bone marrow from Boran cattle compared to that from N’Dama cattle (p < 0.05). Nucleotide sequence analysis of the 3’ untranslated region (UTR) of the N’Dama and Boran Epo cDNA sequences revealed a polymorphism. Also a single position mutation of Try ——> His close to a unique phosphoserine motif was identified on the predicted peptide sequence of Epo receptor in Boran cattle. These may contribute to the differences in the erythropoietic response observed in the two breeds of cattle. These are the first observations that link a genetic marker (Epo and EpoR polymorphism) to a phenotypic criterion (PCV) for trypanotolerance of cattle. / Ph. D.

Portfolio, from the Latin words meaning "to carry and leaf," originally referred to a case in which to carry paper or drawings. This concept has now expanded to include a collection of like items (stocks or artist’s portfolio) into the realm of education, self directed assessment, and career development consideration. The original idea of the career portfolio was to integrate the National Career Development Guidelines (1989) into a comprehensive career guidance program. Get A Life (1992), a career portfolio developed by the National Occupational Information Coordinating Committee and the Maine Occupational Information Coordinating Committee, was field-tested in 1992. The ultimate success of Get A Life led to the development of the Life Work Portfolio. This product which targeted adults was pilot tested in 1995. Even though the Life Work Portfolio underwent a pilot study prior to publication, this study was the first to look at the Life Work Portfolio in depth, under controlled conditions. The Spring Semester 1996 orientation classes of New River Community College in Dublin, Virginia, were used for this study. Two groups of nontraditional students (ages 23 and up) and two groups of traditional students (ages 18-22) were selected on a volunteer basis (n=26). One nontraditional and one traditional group participated in a structured group setting and completed the Life Work Portfolio in a series of four 1-1½ hour sessions, one per week for four consecutive weeks. One nontraditional and one traditional group completed the Life Work Portfolio in an unstructured setting with help available upon request for a period of four weeks. All participants took part in a focus group at the end of four weeks to elicit responses related to the usefulness of the Life Work Portfolio. Participants completed the Life Work Portfolio Project User Reaction Form and McDaniels Career Transitions Considerations (MCTC) at the end of the fourth session. A descriptive analysis of the portfolios was completed by each participant. Results of the study indicate that the Life Work Portfolio provides a viable tool for traditional and nontraditional students at New River Community College in gathering information, skill identification, goal setting, enhancing self-confidence, and other issues related to successful career transitions. The Life Work Portfolio provided the appropriate structure for the process of lifespan career development to be understood and acted upon. / Ph. D.

A pilot-induced oscillation (PIO) is a dynamic coupling between pilot and aircraft that produces undesired oscillations as a result of attempted pilot control of the vehicle. Present day methods that are intended to predict which aircraft are susceptible to PIO deal primarily with the linear dynamics associated with both the pilot and vehicle. These methods are incapable of handling multiple dynamic effects. An analysis method that is able to handle several dynamic effects simultaneously, including nonlinearities arbitrarily located in both the pilot and vehicle models, is offered. The new unified analysis method draws from recent advances in pilot modeling, stability robustness analysis, and multivariable describing function analysis to solve the problem of identifying aircraft with PIO tendencies. The method handles simultaneous dynamic characteristics as well as nonlinear effects. Control surface rate limiting is one nonlinear effect that is known to contribute to many PIO occurrences. An example analysis of the M2-F2 lifting body is used to demonstrate how several individual dynamic effects can be analyzed simultaneously to predict aircraft PIO susceptibility. In this case, the combined effect of five separate nonlinearities and two linear parameter variations are studied. While the PIO tendency of the M2-F2 is most likely caused by poor flying qualities, a unified PIO analysis shows exactly which dynamic elements couple with the pilot dynamics to cause oscillations. The analysis results show the PIO amplitude and frequency that occurred during flight testing and piloted simulation of the M2-F2 can be accurately predicted assuming a Modified Optimal Control Model of the human pilot and simultaneous limiting in the pilot command and roll feedback channels. / Ph. D.

Marketers frequently use autobiographical memories ads to induce persuasion. However, the few existing studies of autobiographical memories ads have produced inconsistent results regarding their persuasive impact. Moreover, there is little empirical support for the presumed process by which autobiographical memories ads work (i.e., episodic self-referencing). Similar to previous studies, the current study found scant evidence of episodic self-referencing. This study recharacterized self-referencing using the more general term "self-focus". In addition, this study suggested that a schema-based process can better explain the persuasive process in autobiographical memories ads rather than priming a specific episode from one's life. To test these competing explanations (episodic self-referencing vs. schema-based), an experiment was conducted that exposed participants to a Florida vacation package ad either for a spring (schema-consistent) or a Thanksgiving (schema-inconsistent) break. The ad either made no explicit reference to the self (product-focus-ad) or made a reference to a past break experience (self- focus-ad). There were three different versions of the self-focus-ad. Participants in the Self-focus-ad condition simply viewed the ad. Participants in the Self-focus-ad Pre-essay condition wrote an essay on a past break experience prior to viewing the ad. Participants in the Self-focus-ad Post-essay wrote the essay after viewing the ad. The presentation order of two primary dependent measures (product evaluation and cognitive response) was also manipulated. Participants provided product evaluation ratings on the Florida college vacation package. The cognitive response measure was a thought listing task on the advertised product. A computer presented all stimuli and recorded participants' responses. In general, the results support a schema-based process rather than episodic self-referencing in explaining the persuasive impact of autobiographical memories ads when the product evaluation measure preceded the cognitive response measure. A consistent schema-match produced a higher product evaluation than an inconsistent schema-match. Additionally, increasing self-focus after viewing the ad forced participants to contrast their past experience with the ad, resulting in a lower product evaluation. The results suggest that the persuasive mechanism underlying autobiographical memories ads can be better characterized by self-focus and self-relevance rather than by self-referencing of a past event. Implications for persuasion and advertising are discussed. / Ph. D.