Nafion has been the mostly used perfluorosulfonated proton exchange membrane (PEM) in fuel cell. Although a number of problems remain to be resolved on the application of Nafion as a PEM, a less expensive alternative PEM has not been found mainly because of its high proton conductivity. Therefore, much effort has been invested to modify it or find a better and inexpensive material. The exploration of the methods to counter degradation and aging of Nafion is also an important direction of research. In this work, the behavior of PEG in Nafion is investigated with solid state NMR spectroscopy. A series of samples with different PEG sizes and concentrations in Nafion was prepared and the variable temperature proton spectra and longitudinal relaxation times (T1) were measured on two spectrometers. Some interesting findings were made, e.g., the 1H chemical shift of water in concentrated PEG solution decrease while its T1 increase, the higher the concentration of PEG, the larger the increase (of water 1H chemical shift) or decrease (of water 1H T1). These findings provide valuable information on further improving the performance of Nafion in proton conductivity and durability.

The design of reinforced concrete structures for extreme events requires accurate predictions of the ultimate rotational capacity of critical sections, which is dictated by the failure mechanisms of shear, hoop fracture, low-cycle fatigue and longitudinal bar buckling. The purpose of this research is to develop a model for the full compressive behavior of longitudinal steel including the effects of bar buckling. A computational algorithm is developed whereby experimental data can be rigorously modeled. An analytical model is developed from rational mechanics for modeling the complete compressive stress-strain behavior of steel including local buckling effects. The global buckling phenomenon is then investigated in which trends are established using a rigorous computational analysis, and a limit analysis is used to derive simplified design and analysis equations. The derived buckling models are incorporated into wellestablished sectional analysis routines to predict full member behavior, and the application of these routines is demonstrated via an incremental dynamic analysis of a ten-storey reinforced concrete building. The buckling models and the sectional analysis routine compare favorably with experimental data. Design recommendations and topics for further research are presented.

This research, aimed at advancing the theory of environmental hazard adjustment processes by contrasting households from three cities in a high seismic hazard area with households from three other cities in a moderate seismic hazard area. It identified seven types of stakeholders namely, the risk area residents and their families (primary group), the news media, employers, and friends (secondary group), and federal, state, and local governments (tertiary group), and explained why they are relevant to the adoption of seismic hazard adjustments. It also addressed three key attributes— knowledge, trustworthiness, and responsibility for protection—ascribed to these multiple stakeholders and the relationships of these stakeholder attributes with risk perception, hazard intrusiveness, hazard experience, gender, resource adequacy, fatalism and hazard adjustment adoption. It was specifically concerned with the effects of nested interactions due to trust and power differentials among the seven stakeholders, with the self reported adoption of 16 earthquake protective measures at two points in time (1997 and 1999). Some of the key findings indicate that risk perception, gender, fatalism, city activity in earthquake management and demographic characteristics did not significantly predict hazard adjustment adoption. However, all stakeholder characteristics had significant positive correlations with risk perception and hazard adjustment, implying a peripheral route for social influence. Hazard intrusiveness, hazard experience, and stakeholder knowledge, trustworthiness, and responsibility affected the increased adoption of hazard adjustments by households. Particularly important are the peer groups’ (employers, friends and family) knowledge, trustworthiness and responsibility. These findings suggest, hazard managers cannot count only on the federal, state, and local government advisories put out through the news media to affect community decisions and thereby households’ decisions to take protective actions. Instead, hazard managers need to shift focus and work through peer group networks such as service organizations, industry groups, trade unions, neighborhood organizations, community emergency response teams, faith-based organizations, and educational institutions to increase the knowledge, trustworthiness and responsibility of all in the peer group. This will assure higher household hazard adjustment adoption levels, thus facilitating a reduction in post disaster losses and recovery time.

A robust literature documents numerous negative implications of neuroticism for romantic relationships. The current study was the first to demonstrate necessary information regarding how couples can protect against these implications. Given the role of negative affect in the association between neuroticism and relationship difficulties, and given the role of sex in reducing negative affect, the current 8-wave longitudinal study of 72 newlywed couples tested the prediction that sexual frequency would moderate the association between neuroticism and marital satisfaction. Lagged multilevel modeling analyses supported this prediction. Specifically, although neuroticism was negatively associated with changes in marital satisfaction among spouses engaging in less frequent sex over the prior 6 months, neuroticism was unrelated to changes in satisfaction among spouses reporting more frequent sex over the prior 6 months. These findings join others in highlighting the importance of considering the broader context of the relationship to developing a complete understanding of relationship development.

Thesis--University of Michigan. / eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (v. 2, leaves 476-496).

Thesis (Ph. D.)--University of Washington, 2002. / Vita. Includes bibliographical references (p. 133-141).

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Several research studies have examined the link between working memory ability and behavior problems in youth. Research suggests that children with working memory deficits demonstrate lower levels of attention and higher levels of hyperactivity, physical aggression, and other behavior problems. The purpose of this research was to determine the effects of developmental trajectories of working memory on the developmental trajectories of behavior problems. Results suggested that developmental increases in working memory did not lead to developmental decreases in behavior problems. Results from this study suggested that internalizing and externalizing behavior problems increase over the course of childhood. Several variables did lead to developmental change in behavior problems in children. Children who had lower initial levels of working memory increased in internalizing behaviors less than children with higher initial working memory ability. Also, high socioeconomic status led to smaller increases in internalizing and externalizing behavior, high Peabody Picture Vocabulary Test (PPVT) scores led to larger increases in internalizing and externalizing behavior, and high PPVT scores led to larger decreases in inattentive and hyperactive behavior. Results are discussed in reference to current theories about working memory and behavior problems. / text

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In longitudinal studies, observational units (commonly referred to as individuals) drawn from some population of interest are followed prospectively over time, and measurements from each individual are taken repeatedly at different points in time with the ultimate goal of characterizing the important features of the population. Longitudinal data naturally arise in many areas of study, where the characterization of the population may be achieved by investigating the effects of covariates on a response. Two or more correlated responses from each individual are also common in longitudinal studies, giving rise to multivariate longitudinal data. For example, the National Longitudinal Survey of Children and Youth (NLSCY) is a long-term study to observe the development of Canadian children. In this survey, measurements about factors influencing a child's social, emotional and behavioral development are collected over time; anxiety and aggression reported for each child in this study may be considered as two response variables to characterize the emotional and behavioral development of children. Since in longitudinal studies, information is collected repeatedly from each individual over time, the occurrence of an event at a particular time point may increase/decrease the likelihood of the occurrence of another event in future. Failure to take into account this phenomenon in analyzing longitudinal data may lead to erroneous conclusion. Moreover, repeated responses (e.g., anxiety and aggression) from an individual may exhibit correlation over time. Separate analyses of such multivariate longitudinal responses ignore this correlation, and as a result, cannot reveal the potential association among the responses which could be of paramount importance in many applications. Therefore, analysis of multivariate longitudinal data requires substantial extension of the standard longitudinal methods. In this thesis, we describe a methodology based on the transition models for multivariate longitudinal binary data to address the transitional behavior between two states characterized by binary responses for two different responses (i.e., two processes). Transitional analysis of multivariate longitudinal binary data can address the longitudinal association within processes and enable marginal interpretation of covariate effects. In addition, estimation and inference of the association between the processes can also be achieved via such models. We illustrate this approach with an application to the NLSCY data, where anxiety and aggression (two correlated responses) are modeled as a function of covariates (gender, depression of person most knowledgeable, number of siblings and family status) to identify their effects on behavioral development of Canadian children. In addition, the extent and direction of the association between two responses are estimated. Gender of the child is found statistically significant for both directions of transition, i.e., from low to high and high to low, of aggression. On contrary, gender of the child is found statistically not significant for both transitions of anxiety. Meanwhile, depression of person most knowledgeable is found marginally significant in the high to low direction for aggression. For association parameters, all four directions of associations between anxiety and aggression are found statistically significant.