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Neural function depends on precise wiring of axon during development. Previous studies have demonstrated that the erythropoietin producing hepatocellular carcinoma (Eph) family of tyrosine receptor kinases is crucial for the proper development of a number of neural circuits in the mammalian central nervous system (CNS). Mice lacking Eph receptors have been shown to exhibit deficits in pathways which include the thalamocortical, callosal, retinal and corticospinal tract. Due to the large number of Eph family members, the relative contribution of each receptor to axon pathfinding and neural function remains elusive. In this thesis, I have addressed the function of EphA4, EphB2 and EphB3 in the regulating the formation of interhemispheric projections within the forebrain and motor axon connections within the spinal cord using EphA4, EphB2 and EphB3and combinatorial null mice. To perform a detailed examination of the process of axon guidance regulated by these receptors within the forebrain, high resolution magnetic resonance imaging (MRI), immunofluorescence and in vivo stereotactic fluorescent labeling were performed. This work resulted in the development and validation of MRI-based analytic tools performed using EphB2 mutants which we have previously shown to exhibit specific morphologic defects in the anterior commissure (AC). Analysis of EphA4 null mice using high resolution MRI revealed for the first time that in addition to errors of midline crossing, loss of EphA4 activity results in a positional reorganization of the rostral AC. Results demonstrate that while EphB2 and A4 each regulate distinct aspects of guidance within ACpp, these receptors also operate cooperatively to control the guidance of axons in the pars anterior of the AC, a pathway not been previously implicated in Eph-mediated guidance. With respect to the spinal cord, mice deficient in EphB2 and EphA4 display prominent axon guidance errors in the medial subsets of the lateral motor column (LMCm); neurons which normally innervate ventral limb musculature. Finally, I have addressed the functional effect which Eph mutants exhibit with respect to motor behavior by examining a detailed set of motor coordination parameters

Axon guidance is the developmental process where developing neurons navigate their processes based on attractive and repulsive cues. C. elegans has been an instrumental model in the study of neurobiology with one of the key benefits being a relatively simple nervous system which comprises of only 302 neurons. The Eph Receptors are a canonical class of axon guidance molecules and in C. elegans there is only Eph receptor VAB-1. To understand axon guidance it is useful to study the mechanosensory neurons, and in particular a pair of neurons called the PLM (Posterior Lateral Microtubule). In this thesis I undertook a series of projects involving new techniques, and identified gene products that may interact with VAB-1 in the PLMs. I demonstrate that the use of the PLM Length and PLM/Body length ratio at the L1 stage offers an improved way of detecting axon guidance phenotypes. I show proof of concept that use of a light induced cell ablation technique can help study the developing nervous system. Further, I show that with the use of a tissue specific RNAi technique the role of lethal genes in axon guidance can be analyzed. Finally I conducted a screen that identified new effectors of the VAB-1 signal transduction pathway. / Thesis (Master, Biology) -- Queen's University, 2012-10-29 11:31:54.764

A near-optimal feedback guidance algorithm is applied to several different applications in the Circular-Restricted Three Body Problem and in proximity operations in LEO modeled by Keplerian motion. In both scenarios gravitational perturbations are introduced in order to assess the algorithm's robustness. Two forms of the guidance algorithm are studied: a zero-effort miss/zero-effort velocity feedback control law and a zero-effort miss/zero-effort velocity feedback control law augmented with a sliding mode. Both guidance laws have previously been applied to the problems of planetary landing, asteroid intercept, and close-proximity maneuvers near an asteroid. This study is motivated by the growing interest in spacecraft autonomy for proximity operations and in cases where a high frequency of open-loop commanded maneuvers is not practical. Results demonstrate that nominal zero-effort miss/zero-effort velocity feedback guidance is suboptimal in all test cases, but performance can be improved through the addition of waypoints and tuning of guidance law parameters. Additionally, the application of a sliding-mode is shown to overcome limitations introduced by gravitational perturbations in some instances.

Source: Dissertation Abstracts International, Volume: 40-09, Section: A, page: 4902. / Thesis (Ph.D.)--The Florida State University, 1979.

The present study attempted to investigate the interrelationships among Leisure Satisfaction, Job Satisfaction, and Perceived Quality of Life. There is little evidence of research in the literature that specifically addresses the contributions of Leisure Satisfaction and Job Satisfaction to overall Perceived Quality of Life. This investigation is different in that it utilized different methods and employed a different combination of instruments in examining the specific contributions of Leisure Satisfaction, Job Satisfaction, and a set of Demographic variables to overall Perceived Quality of Life. / The subjects consisted of 227 employees of an industrial plant engaged in the light manufacture of food products in the North Florida-South Georgia geographical area. The subjects consisted of 180 males (79.3%) and 47 (20.7%) females. Racially their composition was 170 whites (74.9%) and 57 blacks (25.1%). Over 60% of the subjects were in the 26-45 year old age category, while 78.9% were married. Seventy-four percent of the sample had a gross income from their job of $10,001-20,000 in 1981, while 52.4% had a high school education. There were 12 broad occupational levels of employees identified at the plant. they were as follows: executives, managers, supervisors, salesmen, bakers, shippers, truck drivers, clerical workers, mechanics, light machine operators, packers, and other workers. / The subjects were given a research packet containing a demographic questionnaire and three instruments to assess Leisure Satisfaction, Job Satisfaction, and Perceived Quality of Life. The instruments utilized were the Leisure Satisfaction Scale (LSS), the Job Descriptive Index (JDI), and the Life Quality Inventory (QL). The questionnaire consisted of 143 items including the seven demographic items. All three instruments evidenced adequate validity and high reliability. The sample was not randomly drawn. Participation in the study was voluntary. / Pearson Product-Moment Correlation coefficients and multiple regression analysis were the statistical methods employed to test the interrelationships and the contributions of the independent variables (Leisure Satisfaction, Job Satisfaction, and a set of demographic variables) to the dependent variable (Perceived Quality of Life). The Statistical Package for the Social Sciences (SPSS) Program was utilized to analyze all the data. / The results indicated a strong correlation between the overall scores on the Job Descriptive Index and the Life Quality Inventory. The multiple regression equation indicated that Job Satisfaction, as measured on the JDI, was the strongest predictor of overall QL scores, followed by the demographics put into the regression equation as dummies, and then followed by Leisure Satisfaction as measured on the LSS. / The main purpose of this descriptive study was to add baseline data to the body of knowledge in order to hypothesize and develop theoretical models of the Perceived Quality of Life. No attempt was made to generalize the results beyond the sample. / Source: Dissertation Abstracts International, Volume: 42-06, Section: A, page: 2512. / Thesis (Ph.D.)--The Florida State University, 1981.

This study compared the ratings of 21 male Myocardial Infarction victims with 24 male non victims regarding their behavior and attitudes related to selected proverbs. Both groups were comparable with respect to age, marital status, education, smoking habits, and exercise habits. Each group was administered the Rotan-Peterson Proverb Questionnaire composed of 35 proverbs that represented Type A, Type B and unclassified sayings according to a content analysis. Using a discriminate function analysis, the MI and Non MI groups responded differently to the total questionnaire and subsets of sayings in terms of frequency with which they behaved according to the sayings. There was no significant difference between the groups in terms of their attitudes toward their behavior relative to the proverbs. It was also found that there were five sayings in which the mean of the MI group was significantly different (p < .05) from the Non MIs. Four of the five were Type A sayings in terms of content. Implications of the findings are discussed. / Source: Dissertation Abstracts International, Volume: 42-10, Section: A, page: 4304. / Thesis (Ph.D.)--The Florida State University, 1981.

This study had several objectives: (1) To test whether or not postdivorce counseling was more effective than no counseling. (2) To determine if a structured group counseling modality or a structured individual counseling modality was more effective, as evaluated by increases in self-esteem and overall divorce adjustment. (3) To explore the role of selected contextual and demographic variables on divorce adjustment and self-esteem. / The sample was composed of subjects volunteering for postdivorce counseling. After stratifying for sex, 15 subjects were randomly assigned to group counseling; 10 to individual counseling and 12 to a "minimal contact" group. The sessions, both individual and group counseling, were conducted by the same two therapists, one male and one female. Together they served as a team of cotherapists when they met with the group, and individually they each counseled five subjects. The treatments groups met for an eight week period. A pretest-posttest design was employed with the Raschke Postdivorce Problems and Stress Scale used to measure divorce adjustment and the Rosenberg Self Esteem Scale utilized to measure self-esteem. / Analysis of covariance, with pretest scores as the covariate, revealed no significant differences among the three experimental groups in self-esteem improvement, but did indicate that treatment groups improved significantly more than did the "minimal contact" group on divorce adjustment. No significant differences in effectiveness were discovered between individual and group counseling on divorce adjustment or self-esteem. However, a trend favoring individual counseling for subjects having higher self-esteem was discovered. / Multiple regression analysis revealed that "having a spouse who later insisted on divorce" and "length of separation" were the most important variables in explaining divorce adjustment variance. Similarly, "income" and "first marriage ending in divorce" were the most important variables in explaining self-esteem variance. Contextual variables played a more important role in explaining divorce adjustment variance than self-esteem variance. / This study provides additional support for the effectiveness of short-term structured, individual and group treatment models to facilitate divorce adjustment, although therapists' clinical judgments regarding the most appropriate intervention modality must be made on a basis other than that of their relative therapeutic effectiveness. The clinical preference in the literature for a group modality with short-term, structured treatment models to facilitate divorce adjustment was not supported in this study. / Source: Dissertation Abstracts International, Volume: 42-12, Section: A, page: 5024. / Thesis (Ph.D.)--The Florida State University, 1982.

An analysis of existing theory, research, and practice in the fields both of psychosocial rehabilitation of chronic mental patients and of psychosocial interventions with older persons is presented in this study. Concepts and ideas are extracted from this literature and reformulated in a model of community-based psychosocial rehabilitation specifically tailored to the needs of older chronic mental patients. The model incorporates features of psychosocial rehabilitation such as the concept of a psychosocial center within a community, the importance of membership and of being needed, the expectation for maximum functioning, and the training, support, and opportunities for normalization necessary for such functioning. Companion concepts and themes from the gerontology literature are also included: the potential benefits of productivity and activity within the therapeutic milieu; the provision of opportunities for decision-making; the need for privacy and autonomy; and the importance of maximizing clients' feelings of control over their lives. Practical applications of the model are outlined, and implications for theory and practice are drawn. / Source: Dissertation Abstracts International, Volume: 42-12, Section: A, page: 5025. / Thesis (Ph.D.)--The Florida State University, 1982.

The purpose of this study was to investigate how mental health professionals perceive information in a budget reduction task and the influence of their perceptions on subsequent decision behavior. It was hypothesized that place of employment, level of employment, and the value placed upon information about a problem situation might all have an effect on choice behavior. Subjects (n = 95) were selected from Florida community mental health centers and State mental health hospitals. These mental health professionals were further classified into administrative, supervisory and direct service level positions. An instrument to measure the dependent variable, decision-behavior, was developed and pilot tested before being administered to the subjects. The instrument was a budget-reduction simulation task which presented a set of structured information that was conceptualized as falling into two information domains: rational-quantitative information and social-political information. Principal component analysis supported the existence of these information domains but indicated rational-quantitative information actually represented three underlying patterns of relationships: budget information, decision action plan information and agency descriptive/evaluative information. Place and level of employment were not found to account for a significant amount of the variance in decision-making behavior. The value placed upon the information presented in the budget reduction simulation did account for a significant amount of the variance in decision-making behavior (F(4, 90) = 2.67, p (LESSTHEQ) .04). It was also found that for community mental health staff, the higher the value placed on the budget information the greater the cut in the hospital budget; whereas, for hospital staff the higher the value placed on the budget information the lesser cut from the hospital budget. / This finding appears to indicate that as information becomes more neutral, it is easier for an individual to selectively attend or perceive information in a way consistent with his or her needs. / Source: Dissertation Abstracts International, Volume: 43-09, Section: A, page: 2891. / Thesis (Ph.D.)--The Florida State University, 1982.