The controversy regarding commercial thinning continues to intensify as pine plantation acreage in the south increases. This controversy has caused industrial and nonindustrial landowners to re-examine the economic returns from their plantation investments. This study was undertaken to develop investment guidelines for the management of loblolly pine plantations. Computer simulation was used to evaluate the effect on present value that four future price/market scenarios, three management regimes, and three mechanized thinning systems can have on current thinning investments. When the economic returns from thinning are compared with a no-thin management regime, simulation results indicate that long-term investment advantages favor thinning only slightly, regardless of the future price/market scenario assumed. This slight difference suggests that individual forest product companies may find other reasons such as wood flow, tax advantages, and future product requirements of their manufacturing facilities to be overriding factors for engaging in commercial thinning. Generally, short-run cost and production differences between thinning systems are more significant than the long-term investment effects. Consequently, the type of mechanized thinning system employed has a negligible impact on the total investment. / Ph. D.

The purpose of this study was to identify factors which influenced Virginia Superintendents in Region-Study Group VI between 1978 and 1982 to continue or to vacate the position of superintendent. The population for the study included 29 cases: 19 were classified as continuing superintendents and 10 were classified as non-continuing. The Region of Study included 12 counties and 7 cities. The focus is on the examination of turnover in this geographical region. In carrying out the purpose, the study examined the following research questions: (a) What factors, as perceived by the continuing superintendent, were responsible for or contributed to the decision to continue in the same position? (b) What factors, as perceived by the non-continuing superintendent, were responsible for or contributed to the decision to vacate the position? This descriptive research study used case study methodology to investigate the pertinent factors that influenced the decisions of superintendents in Region-Study Group VI to continue or to vacate their positions of leadership in Virginia School Systems. The study utilized personal confidential interviews as the primary method of data collection. An Interview Guide was developed as the data gathering instrument. Questions were designed to focus on major areas of responsibility of a superintendent. In addition to job competency factors, social, political, personal, community and system demographic factors were examined. A model was designed to check these factors against perceptions of job satisfaction. Data which could be quantified were key-punched for analysis. The chi square test was applied. Factors which appeared to be statistically significant from the chi square analysis of continuing and non-continuing categories included: Community Factors, Social Factors, Job Competencies--Board Relations, Business and Fiscal Management, Curriculum and Instruction, and student Personnel Services. Areas of the interview which could not be easily quantified were reported in narrative form with case specific data. The following case specific information was reported as reasons for staying on the job by the continuing superintendents: (a) positive board relations, (b) community support, (c) challenge and prestige of leadership, (d) personal preference for a particular commit. Case specific information reported by non-continuing superintendents as reasons for changing jobs or termination included: (a) unsatisfactory board relations, (b) health, (c) to avoid community conflict, (d) retirement age, (e) role of change agent, and (f) professional growth--the challenge of a larger school district. / Ed. D.

Job satisfaction has been the subject of a great deal of research by a variety of professional disciplines. However, in school psychology, more speculation than empirical data exists on the topic. Although speculation in the profession has suggested a relatively high degree of job dissatisfaction among school psychologists, a 1982 nationwide study of members of The National Association of School Psychologists failed to substantiate the claims of such speculation. The population of school psychologists in Virginia was chosen for the present study. The study was designed to answer the following four research questions: 1. What are the overall levels of job satisfaction among school psychologists in Virginia? 2. What degree of satisfaction do Virginia school psychologists express with each of 20 subfactors of job satisfaction? 3. What is the relationship between overall levels of job satisfaction and selected demographic variables? 4. How does the job satisfaction of Virginia school psychologists compare with school psychologists nationally? Data were collected via mailed surveys using a demographic data form and a modified form of the Minnesota Satisfaction Questionnaire {MSQ). Four hundred and thirty-nine school psychologists were initially mailed survey materials, and a response rate of 87.36% was obtained. Of this total, two hundred and sixty-seven met the requirements necessary to be included in data analysis. Frequency counts of modified MSQ responses revealed that 84.27% of the school psychologists indicated that they were either satisfied or very satisfied with their jobs. Subscale means and 95% confidence intervals on the modified MSQ indicated that Virginia school psychologists were satisfied with 18 of the 20 subfactors of job satisfaction measured. Only the scales of school system policies and practices, and advancement had means and confidence intervals which fell completely within the dissatisfied range. Multiple regression procedures were used to determine the relationships between overall job satisfaction scores and demographic variables. Three significant predictors of job satisfaction emerged: membership in the Virginia Association of School Psychologists (positively related), membership in the National Education Association (negative related), and contract length (negatively related). This model explained 9.25% of the total variance and overall job satisfaction scores. Analysis of variance procedures were used to compare the job satisfaction of Virginia school psychologists with that of a national sample of school psychologists. Results indicated that Virginia school psychologists were more satisfied with their job security but less satisfied with their compensation, than were their national counterparts. Results of multi-group comparisons of covariance structures available in the computer program LISREL indicated that for the demographic variables studied with the exception of age, no differences existed between Virginia school psychologists and the national sample regarding the relationship of that variable with total job satisfaction scores. Several implications were drawn from the results of the study leading to recommendations for school psychologists, trainers and employers of school psychologists, and professional school psychology organizations. The recommendations focused on development of advancement opportunities for school psychologists, methods for reducing dissatisfaction associated with school system policies and practices, and topics for additional research. / Ed. D.

The major purpose of this study was to test Erik Erikson's epigenetic concept that the achievement of a reasonable sense of ego identity during adolescence is a prerequisite to the establishment of intimate relationships in adulthood. The sample consisted of 400 couples. Their names were drawn from a population of 1600 names which had been compiled from twelve church directories. The adjusted sample was 378 couples of which 88 chose to participate by returning completed questionnaires. The participants were typically white, well educated, well employed, in first marriages and fairly consistent in religious attendance. The project questionnaire was completed by both marital partners. It consisted of two scales and demographic questions. The Ego Identity Scale as developed by Rasmussen (1961) was used to measure the degree of identity obtained by all participants. The Personal Assessment of Intimacy in Relationships as developed by Olson and Schaefer (1981) was used to measure the degree of perceived intimacy on five dimensions within dyadic relationships. The hypotheses tested were designed to examine Erikson's epigenetic theory. Briefly, it was hypothesized that (1) spouses would have similar levels of ego identity development; (2) the identity of one spouse would be related to the intimacy of the other; (3) an individual's ego identity would be related to his/her achieved intimacy; and (4) demographic variables would not be found to influence ego identity. Husband and wife models were also compared. The ego identity scores of spouses were found to be related; no relationship was found between the ego identity of one spouse and the perceived intimacy of the mate; a significant relationship was found to exist between an individual's degree of ego identity development and his/her perceived level of intimacy across five intimacy dimensions; and demographic variables were not found to influence ego identity development. Interesting similarities and differences were found between husband and wife models. Generally, results reinforced Erikson's epigenetic concept. Further research was suggested to differentiate between male and female models and to assess the effectiveness of various therapeutic interventions by levels of couple identity development. / Ph. D.

This dissertation is a study of the development of property rights in the coal industry as defined by Federal legislation. Previous analyses have argued that property rights develop efficiently and have employed a neoclassical model to study this development in the political market. This study asserts that the neoclassical model is inappropriate for analyzing the political market. This study concentrates on the coal industry, analyzing the historical events surrounding development of the property rights structure. A price theoretic approach is employed to determine whether changes in the property rights structure results in greater efficiency for the coal industry. The evidence provided in the study does not support use of the neoclassical model. The model is too constrained and does not allow the inclusion of nonmarket factors in the analysis. / Ph. D.

The problem of identifying three dimensional objects from their two dimensional perspective projections is an important one in computer vision. A segmentation procedure is described here to extract features from a simulated image, then a matching procedure which finds the three dimensional objects in the picture is discussed. An image: a photograph taken by a camera with fixed focal length, is given, and a three dimensional wire frame object model is also given. Each object in the model is composed of planar arcs. The arc is bounded by connected line segments or conics. The input image is a simulated photographs of some objects of our model, the problem is to identify what these objects are. The two dimensional data structure we derived from image are equations of each planar arc. The data stored in the database are equations of the boundary pieces of the three dimensional object. Our aim is to find the match between the given three dimensional data structure and the two dimensional data structure. The method used here is a numerical analysis nonlinear optimization. / Ph. D.

Test and measurement bias in special education diagnosis has been well documented. Boys, linguistic and ethnic minorities, and children with behavior problems are among those overrepresented in several handicap categories, including speech impairment. Recent evidence indicates that variables associated with test interpretation or diagnostician background (non-measurement factors) may be better predictors of diagnostic bias. This study investigated the ability of non-measurement factors to predict the diagnostic decisions made for 345 speech impaired children enrolled in Head Start. Computer Assisted Telephone Interviews and Case File Review were used to collect data about (1) child characteristics, (2) diagnostic criteria, and (3) diagnostician background. Hierarchical regression procedures were used to test the predictive power of these three blocks of variables and of specific variables within each block. The diagnostician's rating of articulation severity was the criterion variable. The test score was the best predictor of articulation severity rating; non-measurement factors were not found to be effective predictors of the articulation component of speech diagnosis. There was some indication, however, that non-measurement factors may be related to the language component of speech assessment. Further investigation of the language severity rating and of other non-measurement factors was suggested. / Ph. D.

Recently, the number of digital imaging systems incorporated into information display applications, such as military and industrial aerial reconnaissance, has increased rapidly. These imaging systems provide considerable flexibility for the processing and enhancement of information that otherwise might be unnoticed in conventional imaging systems. Many of the digital enhancement techniques, however, have not been subjected to systematic evaluations to examine their influence upon operationally relevant human task performance. This paper reports the findings of a segment of an ongoing research program designed to establish a digital image database, to standardize a set of experimental procedures of obtaining human performance data, and to relate these performance measures to various image display conditions. The image database consists of low-altitude aerial scenes of various military and. civilian installations. Original transparencies were digitized with a microdensitometer to generate the image database for magnetic tape storage. The digitized images were then degraded by blur and noise to simulate various levels of system resolution and system signal-to-noise ratio, respectively. Two experimental tasks were developed to assess the effects of digital image quality upon human performance characteristics of interest to the military reconnaissance community. An information extraction task required the human observers to answer a series of questions pertaining to the essential elements of information with each image. A subjective rating task required observers to estimate the extent of image interpretability. Using military photointerpreters as subjects, studies were conducted to assess the effects of image degradations (blur and noise) and image enhancement/restoration processing on human performance. The studies employed high-resolution, black-and-white CRT monitors to display the digital images. Results indicated that both blur and noise image degradations impaired interpretability of the imagery and that several enhancement/restoration processing techniques substantially improved interpretability of the imagery. These results provide useful information for users of digital imaging systems and for researchers to aid future developments of digital image processes. / Ph. D.

A degenerated three-dimensional finite element based on the total Lagrangian, incremental, formulation of a three-dimensional layered anisotropic medium is developed, and its use in the geometrically nonlinear, static as well as dynamic, analysis of layered composite plates and shells is demonstrated via several example problems. For comparison purposes, a two-dimensional finite element based on the Sanders shell theory with the von Karman (nonlinear) strains is also presented. The elements have the following features: • Geometrically linear and nonlinear analysis • Static and transient analyses • Natural vibration (linear) analyses • Plates and shell elements • Arbitrary loading and boundary conditions • Arbitrary lamination scheme and lamina properties The element can be used, with minor changes, in any existing general purpose programs. The 3-D dimensional degenerated element has computational simplicity over a fully three-dimensional element, and the element accounts for full geometric nonlinearities in contrast to the 2-dimensional elements based on the Sanders shell theory. As demonstrated via numerical examples, the deflections obtained by the 2-D shell element deviate from those obtained by the 3-D element for deep shells. Further, the 3-D element can be used to model general shells that are not necessarily doubly-curved. For example, the twisted plates can not be modeled using the 2-D shell element. Of course, the 3-D degenerated element is computationally more demanding than the 2-D shell theory element for a given problem. In summary, the present 3-D element is an efficient element for the analysis of layered composite plates and shells undergoing large displacements and transient motion. / Ph. D.

Much of the prior research on the psychosocial aspects of end stage renal disease (ESRD) has focused solely on the individual, without considering the family's role in patient adjustment. Little research has been conducted on the contextual elements of the patient's adjustment to renal failure and dialysis. It was the purpose of this study to assess the effect of family relationships on a patient's health locus of control as a measure of adjustment to ESRD. Health locus of control was hypothesized to be dependent on the family relationship variables of cohesiveness, adaptability and independence; as well as a communications variable measuring incongruent communications. From the general context of the double bind a path model was constructed to estimate the associations among the variables. Data was collected and analyzed on 91 ESRD patients from four dialysis treatment centers and a sample of Continuous Ambulatory Perotineal Dialysis patients. The results of this research suggest that the double bind theory may be an excellent explanatory paradigm for patient adjustment to chronic illness. It was found that the greater the perceived paradox in family communications the more likely the patient was to subscribe to an externally oriented health locus of control. The family relationship variables were found to be indirect predictors of health locus of control, acting through the family communications process. / Ph. D.