A complete record from colonization to extinction reveals density dependence and the importance of winter conditions for a population of the silvery blue, Glaucopsyche lygdamus.

Butterflies in the family Lycaenidac are often the focus of conservation efforts. However, our understanding of lycaenid population dynamics has been limited to relatively few examples of long-term monitoring data that have been reported. Here, factors associated with population regulation are investigated using a complete record of a single population of the silvery blue, Glaucopsyche lygdamus Doubleday (Lepidoptera: Lycaenidae). Adults of G. lygdamus were first observed in an annual grassland near Davis, California, in 1982 and were last seen in 2003. Relationships between inter-annual variation in abundance and climatic variables were examined, accounting for density dependent effects. Significant effects of both negative density dependence and climatic variation were detected, particularly precipitation and temperature during winter months. Variation in precipitation, the strongest predictor of abundance, was associated directly and positively with butterfly abundance in the same year. Winter temperatures had a negative effect in the same year, but had a lagged, positive effect on abundance in the subsequent year. Mechanistic hypotheses are posed that include climatic effects mediated through both larval and adult plant resources

Product Market Competition and Human Resource Practices: An Analysis of the Retail Food Sector

The rise of super-centers and the entry of Wal-Mart into food retailing have dramatically altered the competitive environment in the industry. This paper explores the impact of such changes on the labor market practices of traditional food retailers. We use longitudinal data on workers and firms to construct new measures of compensation and employment, and examine how these measures evolve within and across firms in response to changes in product market structure. An additional feature of the analysis is to combine rich case study knowledge about the retail food industry with the new matched employer-employee data from the Census Bureau.

Romantic Relationship Quality and Psychosocial Adjustment in Mid-Adolescence

Committed romantic relationships are central to the well-being of adults. The onset of these romantic relationships occurs during adolescence, but much remains unknown about the manner in which adolescent relationships mimic or differ from those present in adulthood. Survey data were collected to investigate whether adolescents demonstrate the same gender differences in “withdrawal-and-aggression” vs. “tend-and-befriend” patterns of behavior in low-quality romantic relationships as those observed in adulthood. We hypothesized that (a) relationship quality would be associated with interpersonal measures of psychological adjustment (bullying and excessive reassurance-seeking); (b) boys would be distressed by the absence of positive relationship qualities and the presence of negative relationship qualities whereas girls would be distressed by the presence of negative qualities, and (c) boys would demonstrate bullying behavior as a measure of maladaptive function whereas girls would demonstrate excessive reassurance-seeking behavior. Hierarchical regression results indicated that the absence of positive qualities in a romantic relationship is associated with higher levels of self-reported excessive reassurance seeking for girls only, and the presence of negative qualities in a romantic relationship is associated with higher levels of peer-reported bullying for boys and girls. Results are discussed and related to findings from the adolescent and adult romantic relationship literature. Implications, limitations, and future directions are presented.Bachelor of Scienc

Product Market Competition and Human Resource Practices: An Analysis of the Retail Food Sector

The rise of super-centers and the entry of Wal-Mart into food retailing have dramatically altered the competitive environment in the industry. This paper explores the impact of such changes on the labor market practices of traditional food retailers. We use longitudinal data on workers and firms to construct new measures of compensation and employment, and examine how these measures evolve within and across firms in response to changes in product market structure. An additional feature of the analysis is to combine rich case study knowledge about the retail food industry with the new matched employer-employee data from the Census Bureau.supermarkets, human resource practices, competition, internal labor market, wage growth, Labor and Human Capital, Marketing,

Decomposing the Sources of Earnings Inequality: Assessing the Role of Reallocation

This paper exploits longitudinal employer-employee matched data from the U.S. Census Bureau to investigate the contribution of worker and firm reallocation to changes in earnings inequality within and across industries between 1992 and 2003. We find that factors that cannot be measured using standard cross-sectional data, including the entry and exit of firms and the sorting of workers across firms, are important sources of changes in earnings distributions over time. Our results also suggest that the dynamics driving changes in earnings inequality are heterogeneous across industries.inequality, linked employer-employee data, sorting

Excellence in Supervision: Listening to Our Students

This essay reports on research, using quantitative and qualitative methods, to better understand the experience of students in relationship to their supervisors and experience of field education

Decomposing the Sources of Earnings Inequality Assessing the Role of Reallocation

This paper uses matched employer-employee data from the Longitudinal Employer Household Dynamics database to investigate the contribution of worker and firm reallocation to within industry changes in wage inequality between 1992 and 2003. We find that the entry and exit of firms and the sorting of workers and firms based on underlying worker "skills" are important determinants of changes in industry earnings distributions over time. Our results suggest that the underlying dynamics of earnings inequality are complex and are due to factors that cannot be measured in standard crosssectional data.