Description: The activity of plant 9-lipoxygenases (LOXs) influences the outcome of Arabidopsis thaliana interaction with pathogen and insects. Evidence provided here indicates that in Arabidopsis, 9-LOXs facilitate infestation by Myzus persicae, commonly known as the green peach aphid (GPA), a sap-sucking insect, and infection by the fungal pathogen Fusarium graminearum. in comparison to the wild-type plant, lox5 mutants, which are deficient in a 9-lipoxygenase, GPA population was smaller and the insect spent less time feeding from sieve elements and xylem, thus resulting in reduced water content and fecundity of GPA. LOX5 expression is induced rapidly in roots of GPA-infested plants. This increase in LOX5 expression is paralleled by an increase in LOX5-synthesized oxylipins in the root and petiole exudates of GPA-infested plants. Micrografting experiments demonstrated that GPA population size was smaller on plants in which the roots were of the lox5 mutant genotype. Exogenous treatment of lox5 mutant roots with 9-hydroxyoctadecanoic acid restored water content and population size of GPA on lox5 mutants. Together, these results suggest that LOX5 genotype in roots is critical for facilitating insect infestation of Arabidopsis. in Arabidopsis, 9-LOX function is also required for facilitating infection by F. graminearum, which is a leading cause of Fusarium head ...

Description: The field of strategic management addresses challenges that firms encounter in an attempt to remain competitive. The ability to explain variation in firm success through examination of knowledge flows has become a prominent focus of research in the strategic management literature. Specifically, researchers have sought to further examine how firms convert knowledge, a phenomenon conceptualized as absorptive capacity. Absorptive capacity is the firm’s ability to acquire, assimilate, transform, and exploit knowledge. Few studies have captured the richness and multi-dimensionality of absorptive capacity, and it remains to be understood how the dimensions of the phenomenon convert knowledge. Furthermore, how absorptive capacity influences the firm remains to be understood. To address these research gaps, this dissertation seeks to (1) determine how absorptive capacity converts knowledge, and (2) determine how absorptive capacity influences firm capabilities. The research questions are investigated using structural modeling techniques to analyze data collected from software-industry firms. The findings offer contributions to the absorptive capacity and capability literatures. For example, absorptive capacity is hypothesized to consist of complex relationships among its internal dimensions. However, findings of this study suggest the relationships among the dimensions are linear in nature. This finding is in line with the theoretical foundations of and ...

Description: Despite socioeconomic disadvantages, less acculturated Mexican Americans tend to exhibit better mental health than their more acculturated counterparts. However, in the case of older Mexican American adults, research has demonstrated the opposite to be true (Gonzalez, Haan, & Hinton, 2001). A variable of interest potentially responsible for this difference is social support. Thus, the current study proposed to investigate the mediation and moderation effects that social support has on the relationship between acculturation and depression in older Mexican American adults age 60 or older. Data from the Health and Retirement Study (HRS) was analyzed. Results showed that the mediating effect of contact with one’s children (-.109*) and the moderating effect of total social support and contact with one’s children (-.127*; -.103*) were statistically significant in the relationship between acculturation and depression. Although these effects are small they may still hold important implications for better understanding this population.

Description: This research is a descriptive analysis answering the question, what measures are currently taken by the leadership―boards of trustees and superintendents of schools―of Texas school districts to prevent embezzlement? The research perspective utilized was quantitative with a descriptive, cross-sectional design. Data collection was accomplished through a survey with questions constructed from the most commonly recommended strategies discovered through the review of literature. The survey was distributed to the 1031 superintendents of school districts in Texas via email. The response rate was 33% or 339 returned surveys. The data set created concentrates on the four most common preventive measures: policy and procedure, management, auditing, and ethics. These measures are considered as they function to interrupt the principles of the fraud triangle. Comparisons were completed regarding region, district size, superintendent tenure and superintendent experience. Policy adoption was found to be extremely widespread. Procedures written to fully implement policy were less prevalent. Review of management practices found problems concerning credit cards, personnel evaluations, and password access to multiple computer finance recordkeeping systems concentrated in one employee. External auditing programs were universal due to statutory mandate but internal auditors and internal audit committees were few. Ethics training for business office personnel existed but with ...

Description: Alpine zooplankton are exposed to a variety of stressors in their natural environment including ultraviolet radiation. Physiological coping mechanisms such as the accumulation of photoprotective compounds provide these zooplankton protection from many of these stressors. Elevated levels of carotenoid compounds such as astaxanthin have been shown to help zooplankton survive longer when exposed to ultraviolet radiation presumably due to the strong antioxidant properties of carotenoid compounds. This antioxidant capacity is important because it may ameliorate natural and anthropogenic stressor-induced oxidative stress. While previous researchers have shown carotenoid compounds impart increased resistance to ultraviolet radiation in populations of zooplankton, little work has focused on the toxicological implications of PAH induced phototoxicity on zooplankton containing high levels of carotenoid compounds. This thesis discusses research studying the role that carotenoid compounds play in reducing PAH induced phototoxicity. By sampling different lakes at elevations ranging from 9,500' to 12,700' in the front range of the Colorado Rocky Mountains, copepod populations containing different levels of carotenoid compounds were obtained. These populations were then challenged with fluoranthene and ultraviolet radiation. Results discussed include differences in survival and levels of lipid peroxidation among populations exhibiting different levels of carotenoid compounds, and the toxicological and ecological implications of ...