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For many children and adolescents growing up in socioeconomic disadvantage, the conditions of everyday life are characterized by persistent exposure to risks and stressors, such as family turmoil, deviant peer groups, and unsafe neighborhoods. However, there has been little research that has directly examined such experiences in the everyday lives of low-income youth. As such, little is known about the effects of daily stressors, both in-the-moment and across developmental time, as well as which youth may be most susceptible to positive and negative experiences in daily life. This dissertation has two overarching aims: (1) to better understand how daily experiences affect adolescents' health and behavior, and (2) to test for characteristics that may help identify adolescents who are more sensitive to their daily environments than others. Chapter 1 reviews theory and research on the everyday environments of children living in socioeconomic disadvantage. It articulates a within-person framework for understanding how youth change in relation to themselves across changing environmental contexts, and discusses how mobile technologies may help researchers better understand the daily lives of low-income youth. Chapters 2 and 3 provide empirical examples informed by the within-person framework presented in Chapter 1, using mobile phones to repeatedly measure contextual triggers, daily stressors, affect, and behavior in the daily lives of 151 adolescents from low-socioeconomic status neighborhoods. Chapter 2 shows that adolescents were more likely to engage in problem behavior (antisocial behavior and substance use) on days when they did versus did not witness others using substances. Adolescents were especially likely to engage in problem behavior if exposure to others' substance use occurred in outside the home (i.e. in their schools, neighborhoods, or other contexts) versus inside the home. The effects of substance use exposure were stronger for adolescents with the DRD4-7R gene, suggesting a gene-environment interaction occurring in daily life. Chapter 3 shows that adolescents with genetic and behavioral markers (DRD4-7R and low levels of self-control) showed greater day-to-day variability in their affect and behavior as well as greater sensitivity to positive and negative experiences in daily life. The implications of these findings for research, theory, and intervention are discussed.

Today's applications need the functionality of the Grid to break freeof single resource limitations, and in turn, the Grid needs applications in order to properly evolve. Why then are there currently so few applications using grids? We describe some of the problems faced by application developers in moving to the Grid, and show how grid application frameworks should overcome these difficulties. Such frameworks will define the relationship between the Grid and applications, providing consistent abstract interfaces to grid operations and allowing applications to include these operations independently from their actual implementation. These user interfaces should be application focused, capturing the semantics of the underlying operations, then driving grid developmen tto support these needs. Building the right interfaces motivates a detailed classification of applications and operations for the grid, and we provide a simple taxonomy in this paper, outlining important new directions in which it should be extended. We describe the rationale and design of a Grid Application Toolkit in the GridLab project, which will provide a comprehensive language and implementation neutral framework for encapsulating grid operations that will greatly simplify and accelerate future grid application development.