Theses and Dissertations

This thesis conducted an evaluation of the performance and return on investment of a 2 x 6m, simple design greenhouse, as a climate control technology. Specifically, differences in internal microclimate conditions between a greenhouse treatment plot, and sun and shaded control plots were assessed and related to observed differences in crop yields across these plots. Growing conditions and productivity of two crops, tomato and swiss chard, which were grown over summer and winter growing seasons, respectively, were compared. It was found that the greenhouse was associated with improved growth conditions (as measured by the R-Index) for both crops but resulted in higher productivity only for tomatoes. Return on investment and food security impacts from the scaling of greenhouse agriculture were also explored.

Prior research has established a relation between parenting behaviors and symptoms of child psychopathology, and this association may be influenced by both genetic and environmental factors. Gene-environment correlation, or the influence of a child’s genes on the environment they receive, represents one possible mechanism through which genes and environment combine to influence child outcomes. This study examined evocative gene-environment correlation in the relation between parenting and symptoms of child psychopathology in a sample of 676 twins (51.5% female, 58.5% Caucasian, 23.7% Hispanic/Latinx, primarily middle class, MAge=8.43, SD=.62) recruited from Arizona birth records. Using univariate ACE twin biometric models, genetic influences were found to moderately contribute to internalizing symptoms (A=.47, C=.25, E=.28), while externalizing (A=.86, E=.14) and ADHD (A=.84, E=.16) symptoms were found to be highly heritable. The genetic influences for positive (C=.54, E=.46) and negative (C=.44, E=.56) parenting were smaller and found to be nonsignificant. The correlations between parenting and types of psychopathology were examined and bivariate Cholesky decompositions were conducted for statistically significant correlations. Negative parenting was moderately positively correlated with externalizing and ADHD symptoms; the relation between externalizing symptoms and negative parenting was found to be due to shared genetics, whereas the relation between negative parenting and ADHD symptoms was due to the shared environment. The mixed results regarding the role of gene environment correlation in relations between parenting and child psychopathology indicate that further research on the mechanisms of this relation is needed.