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Prior research has indicated that posttraumatic stress disorder (PTSD) Criterion A2 (i.e., the stipulation that an individual must experience intense fear, helplessness, or horror during an event that threatened the life or physical integrity of oneself or others to be eligible for the PTSD diagnosis; Diagnostic and Statistical Manual of Mental Disorders, 4th, ed., text rev., DSM-IV-TR; APA, 2000) is not positively predictive of PTSD diagnostic status. However, the exact reason for the poor predictive validity is unclear. It may be that changing the operational definition of Criterion A2 (e.g., broadening the definition to include additional peritraumatic reactions) will improve its predictive validity. The current investigation attempted to answer this question, as well as examining several other aspects of the peritraumatic experience. Specifically, three studies were conducted. Study 1 examined whether the ability of the peritraumatic response to predict PTSD can be improved by reconstituting the operationalization of this experience. Study 2 investigated whether this new operationalization of the peritraumatic experience can differentiate between PTSD and other psychiatric disorders (i.e., Major Depressive Disorder, Substance Use Disorders). Study 3 explored how different methodologies for assessing responses to trauma cues (i.e., retrospective reports, self-report and psychophysiological data gathered from a laboratory-based trauma monologue) compare in their ability to predict PTSD. Two-hundred thirty four female crime victims (151 victims of rape; 83 victims of physical assault) were recruited as part of a National Institute of Mental Health (Dr. Patricia Resick, Principal Investigator) prospective longitudinal study designed to examine factors associated with recovery from a recent assault. Results indicated that, consistent with past literature, the three Criterion A2 variables (i.e., peritraumatic fear, helplessness, and horror) were not predictive of PTSD diagnostic status or PTSD symptom severity. However, peritraumatic anxiety was predictive of PTSD diagnostic status, and a dimensional variable assessing the dissociative emotions was predictive of PTSD symptom severity. The predictive utility of the peritraumatic experience was found to be unique to PTSD; although peritraumatic anxiety was predictive of PTSD diagnostic status, none was predictive of the other forms of psychopathology examined (i.e., MDD, Substance Use Disorders). Finally, results indicated that several of the peritraumatic responses were predictive of both self-reported distress and measures of arousal (i.e., amplitude of skin conductance responses) during a laboratory-based trauma monologue. However, the three sets of measures (i.e., peritraumatic responses, self-reported distress, and psychophysiological responses) were differentially predictive of PTSD. Limitations of the study, as well as implications of the findings, are discussed. / Psychology

One of the fundamental concerns of developmental psychology is the nature of continuity and change across development. The present study investigated the continuity of social competence across developmental periods, paying special attention to the transition from middle childhood to adolescence. Using a birth cohort of youths (277 males, 315 females), I examined the stability of social competence across developmental periods, assessed the relation between quality of early parenting and later competence, and tested how timing of pubertal maturation and school transition impact the stability of social competence, using both variable-centered and person-centered analyses. It was expected that social competence would be highly stable across development, but less stable across the transition to adolescence, and that higher quality parenting would predict greater competence among males and females. Furthermore, I expected that pubertal maturation and school transition would deflect trajectories of social competence over time, accentuating individual differences (e.g., socially competent youths would become more competent, whereas incompetent youths would become less competent). As expected, the nature of social competence was fairly stable from early childhood to adolescence, although there is evidence that social competence is less stable as youth transition from early childhood to middle childhood and from middle childhood to adolescence. Moreover, individuals with warm parenting evinced greater social competence across time. Consistent with my hypothesis, off-time pubertal maturation and school transition accentuated individual differences in social competence, increasing social competence among more competent youths, and further diminishing social competence among less competent youths. Finally, I find evidence that experiencing both off-time pubertal maturation and a school transition simultaneously incurred more risk for females, particularly among less competent females, than experiencing only off-time maturation or a school transition. / Psychology

Various approaches for discriminant analysis of longitudinal data are investigated, with some focus on model-based approaches. The latter are typically based on the modi ed Cholesky decomposition of the covariance matrix in a Gaussian mixture; however, non-Gaussian mixtures are also considered. Where applicable, the Bayesian information criterion is used to select the number of components per class. The various approaches are demonstrated on real and simulated data. / Thesis / Master of Science (MSc)

The objective of this research is to explore a methodology that can be used for testing and evaluating AVCS technologies, and, in particular, automatic headway control models for trucks operating on rural highways. The emphasis is put on the realization of vehicle headway control in the real world highway systems. System dynamics has been selected as the simulation tool for developing, testing and evaluating vehicle headway control models. The following behavior of human driver in a real world highway environment is studied and simulated. An automatic headway control model, Multiple-mode Vehicle Headway Control (MVHC) model, is developed for single lane, cars and trucks mixed flow control in a rural highway system. Using safety and motorist comfort as MOE criteria and the acceleration noise as the index of motorist comfort, some selected automatic headway control models are evaluated. This study demonstrated that simulation affords a means of modeling control processes with various certain and uncertain factors, and therefore, it plays a key role in the development of automatic headway control systems. / Ph. D.

The purpose of this study was to analyze commonly used indices of public school funding equity for the Commonwealth of Pennsylvania for the school years 1982-83 through 1992-93. The variables of market value of property, actual instructional expense (AlE), local plus state revenue (revenue), average daily membership (ADM) and weighted average daily membership (W ADM) were collected for five hundred similarly operated school districts. Equity statistics on the variables were generated using a program developed by Verstegen and Stevens (1991). The relationship between the equity statistics generated and legislative actions associated with school funding for the Commonwealth were analyzed. Additionally, an alternative method of funding schools in the Commonwealth was developed based on the 1992-93 school year data. In general, the statistics generated showed a decrease in equity of AIE and revenue distributions from the 1982-83 school year through 1989-90. The last few years studied indicated improvement in the distributions, with the primary source of improvement being a change in the method of state support for special education. The legislative efforts to improve overall support for school districts, especially those found at the less wealthy end of the wealth spectrum, were diminished by the funding formula methodology. This methodology has since been eliminated, and replaced with a guaranteed foundation level of funding, which is still hampered by political considerations. The system of funding public schools in the Commonwealth of Pennsylvania has changed dramatically in the last several years in an attempt to meet the educational mandate found in the constitution of the Commonwealth. The equity statistics and analyses presented here indicate that the system has fallen short of meeting that goal during the period studied. / Ph. D.

The purpose of this research is to evaluate the performance of new corrugated-type embossments developed by Vulcraft Research and Development for their 2VLI and 3VLI composite deck. Performance of deck with the proposed embossment types is compared with that of deck with the existing embossment type, resulting in the recommendation of which type to further investigate for production. The evaluation consists of uniformly loaded full-scale slab tests whose flexural strengths are compared with those given by different strength prediction methods that are alternatives to full-scale testing. The methods used in this study are the First Yield Method (Heagler 1992), the ASCE Appendix D Alternate Method (Standard 1992), and Widjaja's (1997) Iterative Method. Shear bond tests are also performed for deck with each embossment type to evaluate shear resistance specifically, and to provide shear bond data needed to perform the Iterative Method. / Master of Science