Master of Science / Department of Agricultural Economics / Terry Griffin / Farmers and agricultural lenders often seek the ability to identify positive or negative characteristics to improve farm operations. Determining these characteristics has been the goal of many research studies. More often than not, a unique set of uncontrollable events was credited for contributing the majority of one farm’s success relative to their peers. The goal of this study was to evaluate the assumption that farmers can control their financial persistence defined as remaining in their current financial category, based upon a farm’s debt to asset ratio (D/A), and net farm income per acre (NFI acre⁻¹). Financial categories give agricultural producers a concrete answer to the question of one farm’s ability to maintain their financial persistence during market downturns and poor growing conditions and include Favorable, Marginal Income, Marginal Solvency, and Vulnerable. Farmers across the United States are subject to many uncontrollable variables (temperature, precipitation, market volatility, land value fluctuations, interest rates) leaving them vulnerable to agricultural market downturns, such as the one that began in 2014. Seasonal cash inflows and outflows of farms and their profitability create a difficult situation for farmers and agricultural lenders alike to predict the future. Identifying and estimating the likelihood of financial persistence has become an area of interest for farmers, their advisors, and their financial lenders. Currently, agricultural lenders rely on loan assessment techniques, such as net present values and loss-based methods. These techniques fail to account for the unique and often long-term investment nature of farming. If an additional method for identifying at-risk farms or at least understanding the likelihood of persistence in farms could be found, it would provide an insight into the riskiness of lending to a farm and provide agricultural lenders with an additional analysis tool. The dynamic nature of farm financials and the ever-changing variables of farming limit traditional statistical methods. Considering the difficulty associated with predicting farm default rates due to the complexity of the question, a secondary approach is possible. This study utilized an approach in determining farm financial persistence by estimating the Markov Chain probabilities of four financial categories ranging from Favorable, solvent with positive income to Vulnerable, an insolvent and negative income financial position. Kansas Farm Management Association (KFMA) data from 1993 to 2014 were used to estimate the probability of transitioning between financial categories. This thesis combines transition probabilities of Kanas farms and a multinomial logit model (MNL) to identify farm characteristics of significance. The matrix of probabilities generated, when interpreted, provide information about Kansas farms and their probability of financial persistence, and the MNL model allows for insights into favorable or un-favorable farm characteristics. Farms were found to transition easily between financial categories that had the same debt to asset ratio (D/A), but different net farm income per acre (NFI acre⁻¹, positive or negative) indicating that farm income is more easily changed than farm D/A ratios. Farms in the Favorable category (D/A < 0.4, + NFI acre⁻¹) had the largest probability of financial persistence at 0.83, whereas Vulnerable farms (D/A > 0.4, - NFI acre⁻¹) were most likely to transition to the Marginal Solvency category (D/A > 0.4, + NFI acre⁻¹) with a probability of transitioning of 0.55 versus the probability of remaining in the Vulnerable category of 0.33. It was also found that crop mixture and age were not statistically significant in the MNL model, but gross profit margin and a farm’s percentage of owned land out of total crop acres were statistically significant in explaining why farms were in each category.

abstract: Persistence theory provides a mathematically rigorous answer to the question of population survival by establishing an initial-condition- independent positive lower bound for the long-term value of the population size. This study focuses on the persistence of discrete semiflows in infinite-dimensional state spaces that model the year-to-year dynamics of structured populations. The map which encapsulates the population development from one year to the next is approximated at the origin (the extinction state) by a linear or homogeneous map. The (cone) spectral radius of this approximating map is the threshold between extinction and persistence. General persistence results are applied to three particular models: a size-structured plant population model, a diffusion model (with both Neumann and Dirichlet boundary conditions) for a dispersing population of males and females that only mate and reproduce once during a very short season, and a rank-structured model for a population of males and females. / Dissertation/Thesis / Ph.D. Mathematics 2014

This qualitative study addressed the experiences of African American males attending a predominantly White university as undergirded by the social integration aspects of Tinto's model of academic and social integration. The methodology was case study. Sixteen semi-structured interviews were held with currently enrolled seniors to capture the lived experiences of their reasons for attending college as well as major influences that contributed to their persistence decisions. The results revealed emerging themes of positive and negative family influence, religious beliefs, and a sense of self-efficacy as instrumental factors for the students' persistence. The level of social integration tended to differ by the age classification (traditional college-going versus non-traditional college student) and by the level of parental education. The components of the social integration model, as developed by Tinto contributed little to the sample's persistence decisions when compared to the themes presented during the interviews. Three observations emerged from the data: (1) The experiences of the non-traditional aged participants were different from the traditional aged college student experiences; (2) Although the participants experienced varying levels of social integration, for most of the 16 students, their persistence decisions were influenced more by their positive and negative relationships with family, religious beliefs, and sense of self-efficacy than by their interactions with peers and faculty and involvement in extracurricular activities; (3) the responses of the participants enriched and broadened the scope of Tinto's model as well as the current literature pertaining to persistence.

An increasing number of students are selecting for-profit universities to pursue their education (Snyder, Tan & Hoffman, 2006). Despite this trend, little empirical research attention has focused on these institutions, and the literature that exists has been classified as rudimentary in nature (Tierney & Hentschke, 2007). The purpose of this study was to investigate the factors that differentiated students who persisted beyond the first session at a for-profit university. A mixed methods research design consisting of three strands was utilized. Utilizing the College Student Inventory, student’s self-reported perceptions of what their college experience would be like was collected during strand 1. The second strand of the study utilized a survey design focusing on the beliefs that guided participants’ decisions to attend college. Discriminant analysis was utilized to determine what factors differentiated students who persisted from those who did not. A purposeful sample and semi-structured interview guide was used during the third strand. Data from this strand were analyzed thematically. Students’ self-reported dropout proneness, predicted academic difficulty, attitudes toward educators, sense of financial security, verbal confidence, gender and number of hours worked while enrolled in school differentiated students who persisted in their studies from those who dropped out. Several themes emerged from the interview data collected. Participants noted that financial concerns, how they would balance the demands of college with the demands of their lives, and a lack of knowledge about how colleges operate were barriers to persistence faced by students. College staff and faculty support were reported to be the most significant supports reported by those interviewed. Implications for future research studies and practice are included in this study.

The purpose of this study was to examine the relationship between participation in a retention program designed to promote academic and social integration and the persistence rates of first generation, low-income college students at an urban, public multiethnic university. Archival data were collected from the university’s Office of Institutional Research and the retention program office and included SAT/ACT scores, GPA, gender, ethnicity, and program participation data. A total of 292 first-generation, low-income students who were admitted to the university in the summer of 1999 were identified for the study. A group of 166 students were selected for the comparison group because they had not participated in the retention program; 126 students had participated in the retention program. Three major research questions guided this study: (a) Are there differences in persistence rates and other academic characteristics of underprepared, low-income, first generation college students who participate and do not participate in the retention program?; (b) Does involvement in the retention program predict student persistence of first generation low-income, underprepared students?, and (c) Can predictors of GPA be identified for students in the retention program using program and descriptive variables? A series of logistic regression analyses were conducted to assess the relationship between various retention services and the persistence and graduation rates of participants. The results showed that there were statistically significant relationships between participation and non-participation in the retention program and having higher GPAs and higher graduation and persistence rates. Of the four program features, participation in tutoring, workshops, and social events were found to be predictors of graduation. College GPA was also found to be a predictor of graduation for all students. The results also showed that women were more likely to graduate than men.

This research explores the effect that earning professional certificates has on student confidence, motivation, and persistence. For this study, the focus is the student motivation and persistence of nontraditional students who seek to earn a bachelor's degree despite considerable obstacles and challenges. Specifically, this study evaluates the matriculation rates between two cohorts of students who participated in the online PathwayConnect program. The first cohort was encouraged to complete the program and apply for an online bachelor's degree program at BYU-Idaho. The second cohort was also encouraged to apply to an online program, but only after earning a professional certificate in their desired focus of study. The study found that matriculation rates for students who earned a certificate increased over those who followed a traditional path. The research suggests that earning a certificate provided a lift in student confidence and motivation as the significant contributing factors to the positive change.

How do we persist over time: What conditions need to be fulfilled for us to remain the same person from one moment to the next? Two theories have dominated the debate for a longtime: the physical and psychological approaches, which are centred on sameness of body and sameness of psychology, respectively. This thesis will focus on a third theory, the phenomenal approach, which defines persistence as the sameness of consciousness. That is, what is required for persistence is a continuous stream of consciousness. In part 1, I will present and analyse two different arguments that advocate for the phenomenal approach and I will also offer criticism for each argument individually. In part 2 I will present criticism that is directed to both arguments and the view as a whole. I will argue that the phenomenal approach to personal identity over time is an intuitive and convincing alternative at first glance but after deeper analysis it is an inadequate and unsatisfactory argument for personal persistence. Both arguments defend the capacity for consciousness as the condition for persistence but neither is able to define what has the capacity for consciousness and how it could persist without consciousness in a meaningful way.

Guanosine tetraphosphate (ppGpp) is a bacterial signaling molecule involved in activating the stringent response, a cellular reaction to environmental stress that downregulates cell division and metabolism processes to conserve nutrients. The stringent response is implicated in some instances of antibiotic persistence, so broadening the current understanding of ppGpp signaling is useful. This thesis seeks to generate a ppGpp biosensor that will bind ppGpp and emit fluorescent light in its presence, which will allow for improved research into the pathways and functions of the signaling molecule. To generate a novel ppGpp biosensor, I converted a biosensor previously used to detect cyclic di-GMP (a different signaling molecule) to contain a binding site transformed to now bind specifically with ppGpp. The genetic sequence for the cyclic di-GMP binding site was replaced with the ppGpp hydrolase domain which has a specific affinity for ppGpp; however, hydrolase activity would provide unwanted breakdown of the ppGpp, so it is mutated further to neutralize hydrolase activity. The desired outcome of this thesis results in a biosensor with a binding site that has a specific and sufficient binding affinity for the ppGpp molecule. Using this, we can determine how ppGpp levels are regulated in bacteria under conditions of stress, and how this signaling molecule is related to the survival of bacteria in response to antibiotic treatment.

Using 12 years of monthly sweep-net data from 9-12 permanent sampling stations, we evaluated the variability and stability of the dragonfly assemblage in Bays Mountain Lake (northeastern Tennessee, USA). To do this, we adopted the view that a stable assemblage (i.e. one capable of recovering quickly from disturbances) should have low variability (i.e. high persistence of taxa, relatively constant densities, and high rank concordance), except with disturbances more intense and frequent than those in this system. Moreover, a stable assemblage should contain populations that exhibit density dependence and should tend to remain within a restricted range of densities (boundedness), shifting toward a narrow density interval between generations (attraction). To test some specific predictions derived from these views, we analyzed 12-year sequences of larval population sizes just before the onset of emergence for the 13 dominant dragonfly taxa in the lake. Most but not all of the 13 dominant taxa persisted during the 12-year period. Variabilities of taxon densities, measured as standard deviations across generations of log-transformed population sizes, were representative of the broad range for other invertebrates but somewhat higher than those of terrestrial vertebrates. There were fewer than three significant abundance trends over the 12-year period, and rank concordance between generations was high (W=0.716). Density dependence was detected among some of the dragonfly density sequences by five different methods. Using techniques presented in the companion paper, we found strong indications of both boundedness and attraction in the whole assemblage. We conclude tentatively that an assemblage consisting of at least 11 of the 13 dominant dragonfly taxa at Bays Mountain Lake has low-to-moderate variability and is stable, but that the complete 29-species assemblage is probably not stable at the scale of this single lake. We emphasize the need for coupling such long-term descriptive analyses with studies of responses to experimental disturbances.

The obligate intracellular bacterium Chlamydia trachomatis requires iron in order to complete its developmental cycle. Addition of an iron-chelating drug, Desferal (deferoxamine mesylate), to infected cell culture causes Chlamydia to enter persistence. Here, we explore the ability of a stably-transfected cell line with inducible over-expression of the eukaryotic iron efflux protein ferroportin to starve C. trachomatis serovar E for iron. Ferroportin-induced iron removal is perhaps a more direct method of removing iron from the intracellular compartment versus exposure to an exogenous chemical chelator. Following induction, ferroportin-green fluorescent protein (Fpn-GFP) was detected in the plasma membrane, and cells expressing Fpn-GFP remained viable throughout the timescale required for Chlamydia to complete its developmental cycle. Following Fpn-GFP induction in infected cells, chlamydial infectivity remained unchanged, indicating chlamydiae were not in persistence. Ferritin levels indicate only a small decrease in cellular iron following Fpn-GFP expression relative to cultures exposed to Desferal. These data indicate that expression of Fpn-GFP in chlamydiae-infected cells is not capable of reducing iron below the threshold concentration needed to cause chlamydiae to enter persistence.