Two methods, one for the identification and one for the control implementation of distributed-parameter systems are presented. The methods are designed to identify and control the actual distributed system, without resorting to discretization. They are implemented using discrete sensors and actuators. The identification process is carried out in two steps. First, the eigensolution of the distributed system is identified. The lowest frequencies and associated eigenfunctions are identified using an extension of a time-domain approach developed for discrete systems. The extension to distributed systems is carried out in this dissertation. To this end, the sensors output is interpolated to identify the eigenfunctions. Next, the parameters contained in the equations of motion are identified. The motion of distributed-parameter systems is described in terms of partial differential equations, so that these parameters are in general continuous functions of the spatial variables. For vibrating systems, these parameters ordinarily represent the mass, stiffness and damping distributions. These distributions are expanded in terms of finite series of known functions of the spatial variables multiplied by undetermined coefficients. Then, using the identified eigensolution and assuming that the general nature of the equation of motion is known, use is made of the least squares method, in conjunction with the eigenfunctions orthogonality to compute the undetermined coefficients, thus identifying the actual distributed system. The control system design is based on the concept of independent modal-space control. Implementation of the independent modal-space control method requires that the number of actuators be equal to the number of controlled modes. Because the actuators are discrete elements, control spillover into the uncontrolled modes is experienced. The effect of control spillover is to pump part of the energy imparted to the distributed system into the uncontrolled modes. It is shown that when the independent modal-space control method is used, the energy required to control the controlled modes does not depend on the actuators locations, so that the placement of the actuators does not represent a serious problem, as it can for coupled controls. A new concept in extracting modal coordinates from the system output, namely modal filters, is introduced. Modal filters extract the modal quantities from the sensors data by interpolating the output of the sensors to obtain continuous displacement patterns and by performing certain weighted integrations over the distributed domain. If the interpolation functions are chosen following the same guidelines as in the finite element method, the integrations can be carried out as offline computations, which facilitates the control implementation. It is shown that when modal filters are used, control of the actual distributed system is possible and no spatial discretization is necessary. In addition, observation spillover, a possible significant problem when observers are used, is eliminated. Two numerical examples are presented to illustrate the identification and control methods. The methods described in this dissertation are in terms of vibrating systems, with special emphasis on large flexible structures. However, these methods are applicable to any distributed-parameter system. / Ph. D.

Based on pretreatment levels of anxiety, 21 involuntarily confined forensic psychiatric patients were assigned to one of three experimental conditions: stress management training, stress discussion, or no treatment control. Measures of anxiety, physical health, mood, adherence to "irrational beliefs" hypothesized by Ellis (1962) to be related to dysphoric emotions, and a measure of hospital ward adjustment were collected before and after treatment. Subjects originally assigned to the waiting list control group later received exposure to either the stress management training condition or the stress discussion condition. Measures of nonspecific treatment effects generally showed that both group treatments generated equivalent treatment credibilities. The self-report measures of mood and physical health demonstrated that exposure to the stress management training condition resulted in pre to posttreatment improvement, while exposure to the stress discussion condition did not. Also, subjects exposed to the stress management training condition decreased their endorsement of "irrational beliefs," while subjects exposed to stress discussion condition did not. Neither condition resulted in reduced pre to posttreatment changes in state or trait anxiety or improved ward adjustment. It was concluded overall that the stress management training procedure was a moderately effective stress reduction technique for forensic psychiatric patients. Directions for future research are presented as interpretive limitations of the present results. / Ph. D.

There were two primary purposes of this study. The first purpose was to describe and compare the sex role identical and vocational interests of enrollees in traditional and nontraditional displaced homemaker proqrams. The second purpose was to deteraine if sex ro1e identity and vocational interests changed from the beginning to the end of the program cycle. The secondary purposes of this study included (a) a description of the sex role identity of instructors in displaced homemaker programs and a determination of change of sex role identity from the beginning to the end of the program cycle, as well as (b) the establishment of demographic profiles of enrollees and instructors. The sample consisted of 35 enrollees and 10 instructors in four displaced homemaker programs in Virginia. The instruments used in this study were the BEM Inventory and Self-Directed Search. Program information and demographic information on enrollees and instructors was also collected. Descriptive analysis was used for the study. It can be concluded that there was a significant difference in the sex role identity of enrollees in traditional and nontraditional displaced homemaker programs both before and after program activities. Therefore, sex role identity was a significant variable for these selected displaced homemaker programs enrollees. However, due to the small sample, generalizability to the population of displaced homemakers is only speculative. In addition, the data suggested that while most enrollees did not change in their sex role identity from the beginning to the end of the program cycle, those enrollees who did change were enrolled in nontraditional programs and tended to move toward more sex-type roles. As indicated in the literature, strongly sex-typed attitudes may impair the enrollees’ ability to perform in nontraditional occupational settings where flexibility is desirable if not necessary. No significant difference was found in the sex role identity of instructors in traditional and nontraditional programs at either the pre- or posttest stage. Therefore, sex role identity was not a variable determining instructor involvement with a traditional or nontraditional displaced homemaker program. Sex role identity of 40 percent of the instructors moved toward less sex-typed roles form the beginning to the end of the program cycle suggesting an increased flexibility in role. The androgynous role of these instructors could provide a role model which may encourage enrollees to consider a wider range of behavioral and career options. The data suggested that a significant difference in vocational interests existed only at the posttest stage. Thus, it may be concluded that program enrollment may not be contingent upon vocational interest but rather may be dependent upon program availability. In addition, the data suggested that while most enrollees did not change in their vocational interests from the beginning to the end of the program cycle, those enrollees who did change were in traditional displaced homemaker programs. Change in category of vocational interests remained within those occupational areas typically considered feminine. Data on all enrollees indicated a wider distribution of vocational interests at the posttest stage. The career exploration component included in all programs may have attributed to the increased range of vocational interests expressed by enrollees. / Ed. D.

Three experiments were carried out to explore the effects of magnesium deficiency on the activities of the hepatic gluconeogenic enzymes. In Experiment I rats were fed, ad libitum, diets adequate (control) or deficient in magnesium for 12 days. One half of the rats from each treatment group were then fasted for 24 hours. The remaining rats were allowed to eat. The rats were subsequently sacrificed and the following parameters were measured: blood glucose and plasma magnesium, liver magnesium and protein, and the activities of liver glucose-6-phosphatase (G6Pase), fructose 1, 6-bisphosphatase (FDPase), and phosphoenolpyruvate carboxykinase (PEPCK). In Experiments II and III rats were meal-fed diets adequate or deficient in magnesium; in addition, a group of rats was pair-fed to the magnesium-deficient group to test for the effects of anorexia. After 17 days the rats were fasted for 20 hours then sacrificed. The parameters measured in Experiment I were again assessed except liver FDPase and G6Pase were not measured in Experiment III. Feeding a diet deficient in magnesium to the rat produced symptoms characteristic of the deficient state. These symptoms included hyperemia, skin lesions, anorexia, decreased weight gain, and decreased plasma magnesium levels. Anorexia accounted for part, but not all of the decreased weight gain. The concentration of magnesium in the liver of the magnesium-deficient rat was unchanged relative to control values. In the fasted rat, relative to the fed rat, the activities of liver glucose-6-phosphatase (G6Pase) and phosphoenolpyruvate carboxykinase (PEPCK) were increased while that of FDPase was decreased. The response to fasting was similar in magnesium deficient and control rats. In the magnesium-deficient rat, relative to the control rat, the activities of G6Pase and FDPase were unchanged, while that of PEPCK was increased. Anorexia was not responsible for the changes in the activity of PEPCK. Since magnesium was not lost from the liver in magnesium deficiency a direct action of this cation on the activity of PEPCK appears untenable. Magnesium is involved in the secretion of insulin, glucagon, epinephrine and corticosterone. These hormones all affect the gluconeogenic enzymes. A change in the circulating level of one or more of these hormones may be responsible for the effects of magnesium depletion on PEPCK. / Ph. D.

I investigated the Aufwuchs accumulation process on glass slides (chlorophyll, adenosine triphosphate, and diatoms) in experimental streams near Glen Lyn VA (Phase I) and in Stroubles Creek near Blacksburg VA (Phase II). Depopulation experiments carried out during Phase I supported my hypothesis that accumulation rates are greater in reference than in depopulated streams. The effects of depopulation on Aufwuchs biomass accumulation disappeared in about two weeks indicating the rapidity of recovery from short-term catastrophic events. Variability anong replicate slides was generally lower after shorter submergence times than after longer times. In disturbance frequency experiments carried out during Phase I, Aufwuchs accumulation depended on the frequency of copper disturbance. Accumulation was faster in the low stress streams (LSS) than in the high stress streams (HSS) • Resistance of Aufwuchs conununities to an additional Cu disturbance was greater in HSS than in LSS. Resilience of Aufwuchs biomass to the additional disturbance was lower in the LSS than in HSS. Stress resistance tended to be an inverse function of community age and to be greater in HSS than in LSS. Diatom species and diversity were greater in LSS than in HSS. In Stroubles Creek I tested the effect 6f five factors on the Aufwuchs accumulation process and found biomass accumulation was greater in summer than in fall, in riffles than in pools, and in open than in shaded sites. Accumulation differences were not significantly different between upstream and downstream locations or between depopulated and reference areas. Biomass accumulation rates decreased inversely with submergence time. Biomass variability tended to be lower for shorter submergence times and in riffles than in pools. The autotrophic ratio decreased with submergence time. Diatom species number and diversities increased with submergence time. / Ph. D.

Historically, the quantity of hardwood lumber supplied and demanded has fluctuated from year to year while the price of hardwood lumber has trended with the wholesale price index. During the 1970's, production and usage of hardwood lumber trended downward while price increased by over 100 percent. The series of events which occurred during the 1970's, caused industrial users of hardwood lumber to express concern over current and future availability and price of higher grade lumber. Currently, little economic information is available which can explain the behavior of the hardwood lumber market. Furthermore, the lack of such information inhibits the optimal allocation of capital, labor and other resources employed by producers and users of hardwood lumber. The general objective of this study was to provide economic information concerning the production, usage and price of hardwood lumber. Three specific objectives were undertaken in this study: (1) To identify factors affecting hardwood lumber production usage and price, and to measure the impacts of changes in these factors; (2) To identify factors affecting wood furniture manufacturers' demands for hardwood lumber of various species, and to measure the impacts of changes in these factors; and (3) To predict future production, usage and price of hardwood lumber under four different scenarios. Major implications resulting from fulfillment of the first objective were that wage rates and price of output of lumber demanders are the most influential factors in the production and usage of hardwood lumber. Exports of domestically produced lumber were found to influence hardwood lumber price, however, the long-run affects of a change in exports is smaller than the short-run affects. The price of hardwood stumpage was also found to affect the production, usage and price of hardwood lumber; but, the magnitude which stumpage price affects the hardwood lumber market is small when compared to the affects of wage rates and output prices. A major implication of the analysis of wood furniture manufacturers lumber demands was that these manufacturers have a very inelastic demand for lumber as a whole but, their demands for lumber of individual species are much more price elastic. Demand for open grained lumber such as oak and hickory appeared to be more price elastic than the demand for closed grained lumber such as cherry and mahogany. One exception to this rule was the demand for maple lumber which appears to be more price elastic than the demand for any other lumber. Projections revealed little change in production and usage hardwood lumber relative to traditional levels, if the moderate inflation which existed during the mid 1960's and early 1970's is experienced over the next 25 years. Projections also indicate that lumber production and usage will decrease by 50 percent, if the high rate of inflation experienced in 1980 continues over the next 25 years. / Ph. D.

For the most part, women are still employed in traditionally female occupations which require little or no mathematics training. The presence and seeming acceptance of confined, low-status occupations for women represent an enormous loss of economic and intellectual potential for the individual woman and for society as a whole. This study examines the effects of various background, high school, and socio-psychological factors on the mathematics-related attainment of Hispanic, black, and white women. To estimate the contribution of the factors in explaining the variance in mathematics-related attainment, the following variables are considered in a structural equations model: socioeconomic status; high school experience, composed of the number of high school mathematics and science courses, and curriculum; high school achievement, including a mathematics ability score, high school class rank, and academic self-concept; psychological self-concept; perceived college influence of parents, teachers/counselors, and peers; educational and occupational expectations; mathematics-related college experience; sex-role orientation; and family status. The data are provided by the National Longitudinal Study of the High School Class of 1972 (NLS), a longitudinal nationwide survey which follows the progress of high school students to adulthood. Questionnaires were administered to the subjects in 1972, 1973, 1974, and 1976; the overall response rate was 85%. The sample consists of all women who declared a college major for at least two years between 1972 and 1976 (an average of 146 Hispanic, 543 black, and 2918 white women). Descriptive analyses provide group profiles; path analysis techniques are used to compare the influence each of the variables has within and across the three groups. Results indicate that the model explains 46%, 49%, and 52% of the variance for Hispanics, blacks, and whites, respectively; however, the components of the model operate differently for each group. For Hispanic women, educational expectations exert the greatest influence, followed by mathematics-related experience, high school experience, and significant others' perceived college influence. Mathematics-related experience has the greatest total effect for black women, followed by high school experience, high school achievement, and educational expectations; family status has a significant negative direct effect. Mathematics-related experience is also first for whites women, whereas educational expectations is second, high school achievement is third, and socioeconomic status is fourth: additionally, sex-role orientation has a significant direct effect. It is suggested that intervention programs should be designed to address the varying needs of each group of college-bound women and to increase the level of mathematics so that all women, and thus society, can realize their educational and occupational potential. / Ph. D.

Walleyes from several geographic areas have been stocked in Claytor Lake since 1940. Fish presently in the reservoir may have originated from the stocking of Kansas, Nebraska, or Pennsylvania walleyes, or may possibly be descended from a native New River walleye strain. Recent stockings (1974, 1975, 1977, 1979) utilized walleye fingerlings of primarily Kansas origin. A biochemical genetic approach was used to evaluate the present stock structure of Claytor Lake walleyes. Electrophoretic phenotypes for skeletal muscle malate dehydrogenase (MDH) and parvalbumin were identified (using starch and polyacrylamide gel electrophoresis techniques, respectively) for 217 walleyes from three Claytor Lake sites. MDH-B² allelic frequency was significantly higher in stocked than in unstacked cohorts. Muscle parvalbumin frequencies were independent of cohort, but were dependent upon collection site and sex. Parvalbumin-a allelic frequency was higher in male than female walleyes from Claytor Lake. Sex of Claytor Lake walleyes was dependent upon both collection site and cohort, with unstocked cohorts containing more female fish than the stocked cohorts (independence. G-tests). At least two genetically distinct stocks of walleyes presently survive in Claytor Lake. Allelic frequencies of Claytor Lake walleyes were compared (heterogeneity G-test and STP) to those of 428 walleyes collected from Kansas, Nebraska, and Pennsylvania in an effort to identify existing Claytor Lake stocks and to evaluate the effectiveness of recent stockings. Phenotypic frequencies for both MDH and muscle parvalbumin conformed to expected Hardy-Weinberg proportions in samples from all geographic areas, confirming assumptions of genetic control by two co-dominant alleles. Kansas, Nebraska, and Pennsylvania walleyes were different from one another, as were stocked and unstocked Claytor Lake cohorts. Unstocked Claytor Lake cohorts were similar to Nebraska walleyes. Stocked Claytor Lake cohorts were different from all three brood fish sources, probably because stocked cohorts contain both stocked Kansas fish and fish originating from natural reproduction by some other stock in Claytor Lake (probably Nebraska fish). Based on allelic frequency differences between stocked and unstocked cohorts, the stocking of Kansas fingerlings in Claytor Lake during 1975 - 1978 contributed approximately 53 percent of the recruitment to those cohorts in years during which stocking occurred, and approximately 36 percent of the total recruitment to the 1975 - 1978 cohorts. The effectiveness of the present Claytor Lake stocking program is similar to that reported for other walleye stocking programs. Based on 1975 replacement costs for walleye fingerlings, each stocked walleye caught by a Claytor Lake angler during 1976 - 1978 cost approximately $14.78. Low levels of angler harvest may make the continuation of a fingerling walleye stocking program on the reservoir economically unjustifiable. Multiple genetic stocks of walleyes can exist in a relatively small reservoir ecosystem, particularly in mainstream impoundments where very diverse habitats are often spatially isolated due to the large size of these reservoirs. The existence of these multiple stocks is an important consideration for effective management. Particular management strategies may not impact all genetic stocks in the reservoir equally (particularly if they are spatially isolated), and therefore may not produce the desired or expected results if the population is treated as being homogeneous. / Ph. D.

The effectiveness of preoperative relaxation training and preparatory information, separately and in combination, on postoperative pain was examined with respect to surgical patients' coping style (avoidance-sensitization). Subjects were 64 patients undergoing elective cholecystectomy or hysterectomy (abdominal or vaginal) in a large private hospital. Experimenters were advanced clinical psychology graduate students and trained undergraduate research assistants. On the afternoon prior to surgery, patients were contacted, completed an interview that was used to assess their coping style in the surgical situation (Cohen & Lazarus, 1973), and completed the state anxiety portion of the State-Trait Anxiety Inventory. Patients also completed the Pain Rating Index and the Present Pain Index of the McGill Pain Questionnaire. At this point in the preoperative session, patients were presented with materials and/or information corresponding to the group to which they were assigned. Treatments consisted of training in the Benson relaxation technique, receiving information about procedures and specific sensations they would experience, or a combination of relaxation training and information-imparting. Controls talked briefly with the experimenter of feelings about surgery and experiences in the hospital. Patients in all groups were revisited on the second (counting the day after surgery as the first postoperative day) and fourth postoperative days, and again completed the pain measures and the state anxiety measure. Patients were also encouraged to practice the relaxation technique, instructed concerning procedures and sensations they had yet to experience, both, or neither, depending on the group to which they were assigned. After each patient was discharged, his/her medical records were examined and the number and type of analgesics administered during the postoperative period, from the day of surgery until discharge, was tabulated. Preoperative interviews were rated according to coping style and patients were divided into two groups, sensitizers and avoiders. Data were analyzed in a 2 x 4 analysis of covariance. Results indicated that there were no main effects for treatment. It is possible that the treatments provided in this study were too brief to provide an adequate test of their effectiveness for patients in general. There were no significant main effects for coping style, although sensitizers generally reported more pain and received more analgesics than avoiders. An avoidant method of coping appeared to be an adequate method of adjustment to elective surgery and did not result in poorer recovery, as previous authors have suggested. Significant effects on postoperative pain were primarily a function of the interaction between treatment and coping style. Sensitizers reported less pain with relaxation training alone than sensitizers in any of the other groups. This effect was apparently owing to the anxiety-reducing nature of the technique and the fact that it encourages redirection of attention, away from discomforts. Avoiders reported low levels of pain and anxiety with no treatment. However, of the treatments provided, relaxation plus information did reduce some indices of pain below that of avoider controls. Finally, information-imparting did not appear to be beneficial for either sensitizers or avoiders. It was suggested that specific information may contribute to further sensitization to discomforts for sensitizers and conflict with avoidant processes of coping in avoiders. It was also suggested that more extensive preoperative preparation of sensitizers may be necessary to promote habituation to the discomforts of surgery. / Ph. D.

A high performance liquid chromatographic (HPLC) system consisting of an acetonitrile/phosphate buffer, a Spherisorb ODS column, and UV detector was used to separate the B₆ compounds pyridoxol, pyridoxal, pyridoxamine, and 4'-deoxypyridoxine. A gas chromatography (GC) equipped with a ⁶³Ni electron capture (EC) detector was used to separate the N-methyl-bis-trif luoroacetamide derivatives of the B₆ compounds on a l.54m x 2mm i.d. glass column packed with 10% SP2100 on Supelcoport 90-100 mesh at 125°C and an inlet pressure of 40 psig. Clean and successful separations of all the B₆ forms were obtained by HPLC and GC-EC. Total B₆ values as determined by HPLC and GC-EC for all 3 foods were higher than the corresponding total B₆ values as determined by S. uvarum assay. Several of the B₆ vitamer values for foods obtained by GC-EC agree with corresponding values obtained by HPLC. The HPLC method seemed to be the most satisfactory of the 3 methods for the quantitation of B₆ vitamers in foods and has the following advantages: increased sensitivity, method simplicity, and good precision. / Ph. D.