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.

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There are three interrelated concepts of what medical students learn, which include the formal, informal, and hidden curriculum. Several researchers who have investigated notions of the hidden curriculum have demonstrated how the experiences of medical training entrenched in the hidden curriculum can have a profound impact on medical student adaptation. The most influential transitional stage in undergraduate medical education is the third-year clinical clerkship, when medical students transition from classroom learners into clinicians. The Northern Ontario School of Medicine’s (NOSM) clinical clerkship year consists of a mandatory eightmonths of living and working in rural and northern communities throughout Northern Ontario, and learning in the context of rural family practice. Informed by a social constructivist research paradigm, I explored how 12 third-year students described the challenges they had to manage and, in response, the strategies they employed to adapt to their clerkship. I elicited their experiences and perspectives to contribute to a rich understanding of how students at the NOSM describe developing processes of adaptation during the Comprehensive Community Clerkship. Data were collected between August 2011 and April 2012, including: a) pre-clerkship interviews and a demographic questionnaire, b) mobile methods in the form of ‘guided walks’ in the communities, and c) post-clerkship interviews. The quality of the data collection and analysis were enhanced through processes of methodological and interpretive rigour, representativeness and authenticity, rich description and contextual relevance, audit trail, and reflexivity. Through an inductive thematic analysis of the data, the findings provide a rich description of events experienced such as medical training in one’s hometown or a familiar community, iv transitions including adaptation to the clinical setting and to the medical profession, and the influence of the clerkship on career path, personal well-being, and empathy for patients. The findings serve to advance our understanding of how medical students describe developing processes of adaptation throughout a longitudinal integrated clerkship. Implications are considered for medical students, the NOSM, the clerkship communities, and medical schools nationally and internationally. I propose recommendations regarding the suitability of authentic methods in medical education research, and discuss the implications for rural and northern health research.

Social isolation and loneliness are problems that affect the quality of life of many older adults. As the proportion of older people increases in Canada and other nations, studying factors that could improve the quality of life of older people becomes even more crucial. Two studies were conducted drawing on longitudinal data (1996 and 2001) from the Aging in Manitoba Project (Study 1 N = 760) and the Successful Aging Study 2003 (Study 2 N = 228). The main objective of Study 1 was to identify the characteristics of older individuals who differed in their loneliness trajectories over time, allowing for a comparison of those who became lonely, overcame loneliness, were persistently lonely, and were persistently not lonely. A discriminant function analysis examined the social, demographic, physical, and psychological factors as potential discriminators of the loneliness trajectories. When compared to those who were neither lonely at time 1 or time 2, the most important discriminators of persistent loneliness were: living alone, being in poor health, and having low perceptions of control. These predictors were found to be more important than people’s friendships or social activities, highlighting the complexity of loneliness in later life. Study 2 examined the longitudinal relationships between loneliness, health, physical activity, and mortality, and tested Fredrickson’s Broaden and Build Theory that positive emotions (happiness) might serve to “undo” the detrimental effects of negative emotions like loneliness. Regression analyses showed that loneliness longitudinally predicted health, physical activity, and mortality, underscoring the importance of socioemotional variables to health. Moreover, happiness moderated the relationships between loneliness and physical activity and loneliness and mortality. Thus, in support of Fredrickson’s hypothesis, results suggested that happiness has the power to “undo” the detrimental effects of loneliness on physical activity and even on mortality. Being happy may indeed offset the negative consequences of being lonely. Based on these two studies, it was concluded that future interventions could target positive emotions, perceptions of control, and loneliness as ways of ultimately enhancing the lifespan, healthspan, and wellspan of older adults.

In a variety of military operations, a convoy of autonomous followers may need to traverse the leader's path without using Global Positioning System (GPS), lane markers/magnets and/or a vision-based vehicle-following system. This can be achieved by using Visual Teach and Repeat (VT and R), which provides an effective method for autonomous repeating of a previously driven path. This thesis describes the design of a distributed control system that uses the idea behind the VT and R method to allow a convoy of inter-communicable autonomous vehicles to follow a manually-driven lead vehicle's path with a desired inter-vehicle spacing, even when the leader is not in the camera view of the followers. The longitudinal controller is designed for addressing a 1D spacing problem and then combined with a path tracker for tracking a path in a 2D environment. The designed control model is tested in simulations.

In a variety of military operations, a convoy of autonomous followers may need to traverse the leader's path without using Global Positioning System (GPS), lane markers/magnets and/or a vision-based vehicle-following system. This can be achieved by using Visual Teach and Repeat (VT and R), which provides an effective method for autonomous repeating of a previously driven path. This thesis describes the design of a distributed control system that uses the idea behind the VT and R method to allow a convoy of inter-communicable autonomous vehicles to follow a manually-driven lead vehicle's path with a desired inter-vehicle spacing, even when the leader is not in the camera view of the followers. The longitudinal controller is designed for addressing a 1D spacing problem and then combined with a path tracker for tracking a path in a 2D environment. The designed control model is tested in simulations.

Background: The increased amount and diversification of migration flows to Europe are shaping new contexts forthe study of determinants of remittance-sending. Senegalese migration in Spain is one important case,because has increased its presence among other groups in the country and has different characteristics(e.g. younger age structure) compared to Senegalese migrants in Europe. This paper addresses aresearch challenge which can be framed in the three following aspects. First, it analyzes the migrant’sremittance behavior of a particular group of migrants in a specific national context. Second, itacknowledges remittances as transnational practices determined by factors related to incorporationinto host society and ties at origin. Thirdly, the paper provides a longitudinal approach which looks atmigration histories and changes in remittance-sending over time. Objective: The main objective of this paper consists on disentangling the way in which migrant’s remittancebehavior is affected by changes, over time, in individual characteristics (e.g. gender, education),economic integration, (e.g. employment status), and their ties at origin (e.g. family reunification).Thus, there are two research questions to be answered, namely: how are the trajectories of migrantremittances deployed since their arrival into Europe? And, how are these trajectories affected byindividual and family characteristics, as well as economic integration over time? Methodology: The paper is based on retrospective data from the Migration between Africa and Europe (MAFE) andthe Migrations Between Senegal and Spain (MESE) projects. The analysis of determinants ofremittance-sending is divided in two parts. First, a multivariate logistic regression which analyzes theodds of sending remittances (or logit) at any year since arrival into Europe is carried out. Secondly,event history analysis is used to explore the risk of initiating remittance-sending for the first time andthe risk of remittance-sending termination, respectively. In particular, a discrete-time logistic model isperformed to analyze these two processes. Results: Results indicate that despite having arrived relatively recently to Europe, lower educationalattainments and less access to the labour market, compared to other important destinations (e.g.France, Italy), the great majority of Senegalese migrants in Spain start sending remittances duringtheir first years of arrival. Once initiated, international money transfers are kept over time, as morethan two thirds of remitters maintain this economic flow over their stay. In this sense, empiricalevidence of this paper confirms remittances as an important aspect in South-North migration flows,both in terms of the proportion of migrants sending remittances and as a sustained transnationaleconomic practice.

The key to the co-rotational (CR) finite element is the separation between the rigid body motion and the deformational motion. It is this separation which makes it superior to other methods in the analysis of large displacement problems. Since the dynamic analysis of a guyed transmission line system contains large displacements from the vibration of the cable, it is considered appropriate to utilize the technique in the analysis. This thesis re-formulates and simplifies the CR method for such a purpose. Numerical tests show that the time step required for convergence in the present technique is ten times less than that is required for convergence in ANSYS. In the construction of the equation for the prediction of the longitudinal load factor (LLF) for the A402-M guyed transmission line due to cable break events, the tower is modelled using a simplified model of a detailed lattice tower. The simplified model considers latticed tower segment as an equivalent beam segment. The use of the simplified model enables to perform the broken wire dynamic analysis of the ten-span transmission line system within a day or two on a personal computer. Two initiating events are considered: all conductors on one arm break and all cables in one span break. Based on the analysis results, it is found that the LLFs for the all cables break event for the A402-M tower are 5% less than that calculated using the EPRI equation. It is therefore recommended that either the LLFs derived from the EPRI equation or from the proposed equation be used in the design of a guyed transmission tower for the broken wire event. The developed procedure can also be used to predict the LLF for the other type transmission line systems.