Doctor of Philosophy / Department of Diagnostic Medicine/Pathobiology / Ying Fang / Porcine reproductive and respiratory syndrome virus (PRRSV) causes a tremendous economic loss in swine industry worldwide. The capabilities to evade host immune responses and to establish persistent infection are the two hallmark features of PRRSV infection. In this dissertation, the research was mainly focused on investigating the novel mechanisms underlying PRRSV transmission and persistence. In chapter 2, the research was focused on an alternative pathway of PRRSV intercellular transmission. Our data showed that intercellular nanotube connections can be utilized for cell-to-cell spreading the core infectious viral machinery (viral RNA, certain replicases and structural proteins) of PRRSV. Live-cell movies tracked the intercellular transport of a recombinant PRRSV that expressed green fluorescent protein (GFP)-tagged nsp2 in a receptor-independent manner. The cytoskeleton proteins F-actin and myosin-IIA were identified as co-precipitates with PRRSV nanotube associated proteins. Drugs inhibiting actin polymerization or myosin-IIA activation prevented nanotube formations and viral clusters in virus-infected cells. These data lead us to propose that PRRSV utilizes the host cell cytoskeletal machinery inside nanotubes for efficient cell-to-cell spread. This form of virus transport represents an alternative pathway for virus spread, which is resistant to the host humoral immune response. In chapter 3, we further showed that PRRSV infection could induce the formation of nanotubes between infected and uninfected cells following a ROS-dependent nanotube formation model. Co-culturing PRRSV-infected cells with uninfected cells rescued PRRSV-induced cell death. Mitochondrion was observed transferring from uninfected to PRRSV-infected cells. Importantly, impaired formation of nanotube or defective mitochondrion was unable to rescue infected cells from apoptosis/necrosis. Certain PRRSV proteins were detected to associate with mitochondria and transport from infected to uninfected cells through TNTs. Our results suggest that TNTs-transfer of functional mitochondria rescued PRRSV-infected cells from apoptosis/necrosis in the early stage of infection. On the other hand, mitochondria could be utilized as a cargo to transport viral materials for spreading the infection. In chapter 4, a novel mechanism s of PRRSV persistent infection has been studied. In this study, a cellular model of persistent infection was established. Strand-specific quantitative RT-PCR and RNase I treatment analysis showed that double-stranded RNA (dsRNA) conformation existed in persistently infected cells. This data has been further confirmed in vivo by performing two independent PRRSV persistence studies. Immunohistochemistry analysis showed that viral dsRNAs were detected aggregating inside the germinal centers of tonsils and lymph nodes from PRRSV persistence pigs, but RNA array analysis further showed that dsRNA in lymphoid tissues had limited ability to stimulate host antiviral responses during persistent infection stage. These results suggest that the PRRSV dsRNA functions as a mediator for viral persistence. The viral dsRNA persistence in germinal centers of lymphoid tissues may reveal a novel mechanism for PRRSV to escape antiviral immune responses. In summary, this study investigated two novel pathogenic mechanisms of PRRSV infection, which could provide insights on the development of effective control strategies.

Two studies tested a theory of how trait self-esteem moderates behavioral and cognitive persistence in the face of failure. Three primary hypotheses were examined. First, that high self-esteem (HSE) individuals persist more than low self-esteem (LSE) individuals when their initial attempts to reach a goal fail, but subsequent or repeated failures lead HSE individuals to reduce behavioral persistence and pursue goal alternatives more quickly than LSE individuals. Second, that when no goal alternatives are available, HSE individuals behaviorally persist more than LSE individuals. Third, despite reductions in behavioral persistence, LSE individuals do not "give up" on the failed goal but continue to persist cognitively, in the form of aversive ruminations about the failed goal. In a factorial experiment, persistence was examined as a function of self-esteem, degree of failure, and the availability of goal alternatives. As hypothesized, HSE participants behaviorally persisted more than LSE participants after a single failure, but less after repeated failure. However, selfesteem differences in behavioral persistence did not emerge when goal alternatives were unavailable. Partial support was received for the hypothesis that LSE individuals engage in more ruminative persistence than HSE individuals-LSE participants showed higher levels of ruminative persistence on one of two measures of ruminative persistence. The findings regarding behavioral persistence were conceptually replicated, and the hypothesis regarding ruminative persistence received stronger support, in a longitudinal field study in which HSE and LSE participants initially listed their goals and reported on their behavioral and ruminative persistence regarding these goals 5 months later. HSE participants exhibited better calibration between perceptions of goal failure and behavioral pursuit than LSE participants, indicating that increasing perceptions of goal failure were associated with reductions in behavioral pursuit more for HSE than LSE participants. Although they reduced behavioral pursuit relative to HSE participants, LSE participants continued to persist cognitively, by ruminating about their goals more than HSE participants. Discussion focuses on the need to revise traditional views of HSE individuals that emphasize their tenacious persistence and views of LSE individuals that emphasize their tendency to give up in the face of failure. / Arts, Faculty of / Psychology, Department of / Graduate

Benzodiazepines are the most commonly prescribed group of psychotherapeutic pharmaceuticals on a global scale and have been on the market since the 1960s. Benzodiazepines remain in the aqueous effluent from sewage treatment plants and have been found in natural aquatic environments. The aim of this study was to investigate if there is benzodiazepines in natural sediment from Lake Ekoln situated downstream River Fyris in Uppsala, where previous studies have detected high concentrations in the water. The study tested following hypotheses: (1) benzodiazepines are accumulating in sediments; and (2) breakdown of benzodiazepines is slow in sediment resulting in them being preserved in sediments that are several years/decades old. An extraction method for sediment was developed followed by liquid chromatography-tandem mass spectrometry for analysis of oxazepam, alprazolam, clonazepam, flunitrazepam, diazepam and prazepam. All investigated benzodiazepines occurred in the sediment of Lake Ekoln; hence, in line with hypothesis 1, benzodiazepines are accumulating in natural sediments. Further, all benzodiazepines were found in the upper 10 cm of the sediment and oxazepam, clonazepam and diazepam was found at depth below 20 cm, corresponding to an age of more than 20 years indicating that benzodiazepines resists degradation processes in sediment and are persistent for decades as predicted by hypothesis 2. To my knowledge this is the first study demonstrating that benzodiazepines are accumulated and preserved in natural sediments.

Student retention in higher education has become a national problem. At a small midwestern university, the retention rate has been declining, and the freshman to sophomore retention rate was 64% in 2013. The purpose of this intrinsic case study was to investigate ways to improve student retention. Tinto's theory of integration was used to explore the students' and administrators' perceptions of the factors that contribute to poor student retention to graduation. This study analyzed 519 student exit-forms from 2012-2015, 6 semistructured interviews from a purposeful sample of 10 administrators, and an analysis of university archival data. A thematic analysis of the data was completed. The following themes emerged from the analysis: financial problems, academic concerns, and social concerns. Based on the research findings, a 3-day professional development workshop was developed for university administrators, faculty, and staff to help increase their knowledge of retention, reasons why students are not staying, and strategies to academically and socially integrate students into the campus community. The workshop included strategies and activities designed to increase student retention. This study provided administrators, faculty, and staff with strategies and resources to help increase student retention, which may lead to improved graduation rates and less time to graduate.

I coded a random sample of 266 movies to test whether previous researcher’s assertions that the media legitimizes unwanted courtship persistence (UCP) and minimizes stalking behavior is true. Consistent with their assertions, I found that the media does frequently depict stories of unwanted courtship persistence, and they were portrayed, on average, as acceptable. Although pursuers were generally portrayed positively, pursuers who engaged in UCP were more likely to be portrayed negatively than non-UCP pursuers. However, UCP pursuers were more successful than non-UCP pursuers in winning over their love interest. Using Cupach and Spitzberg’s (2004) Obsessional Relational Intrusion (ORI) scale, I found that pursuers engaged in an average of 7 ORI behaviors throughout their pursuit, and many behaviors were portrayed as acceptable, if not positively. Only harassment, coercion and threat, and aggression and violence were portrayed negatively. Implications are tied into Bushman and Anderson’s (2002) General Aggression Model.

Thesis advisor: Michael G. Pratt / Persistence, continuing effort in the face of challenges over time, can have clear benefits for creativity. At the same time, abandonment, stopping effort toward a course of action, is often necessary to help creators move forward towards their best ideas. Creative workers, and the organizations that employ them, thus face a dilemma between forces for persistence and forces for abandonment in developing ideas and projects, what I refer to as the persistence dilemma. Existing theory provides some clues about this dilemma (e.g. theories of motivation or escalation of commitment), but a lack of holistic theorizing leaves many questions outstanding. Through a longitudinal qualitative study of four organizations, I set out to explore how creative workers managed the persistence dilemma. I found that the organizational context shaped how project teams responded to the dilemma. Teams within the startups I studied managed the dilemma with a process focused on commitment. Leaders helped team members transform the ambivalence that resulted from the dilemma into commitment to the organizations core project. Teams in the established organization, by contrast, managed the dilemma with a process focused on balance. The organization focused on balancing forces for abandonment and forces for persistence since both were perceived as necessary and beneficial in their own way. My work has implications for understanding the persistence dilemma, as well as for theories of creativity more generally. / Thesis (PhD) — Boston College, 2021. / Submitted to: Boston College. Carroll School of Management. / Discipline: Management and Organization.

Community colleges across the country have continued to expand since the inception of Joliet<br />Junior College in 1901. The American Association of Community Colleges (AACC, 2010) reported that there are 1,173 community colleges in America, of which 987 are public institutions of higher learning. Additional statistics indicate that there are almost twelve million students enrolled in the community college system (AACC, 2010). Over the years many changes have occurred that affect who attends community college, no change more<br />significant than the focus on meeting the needs of a diverse population. Many unique characteristics, such as being of minority status, being financially disadvantaged, and being a first- generation American make up this diverse new student population. Another unique characteristic of the new student population is being of non-traditional age, which is defined as 25 years old or older (Bean & Metzner, 1985; Cohen & Brawer, 1989; Crosta, Calcagno, Jenkins, & Bailey 2006). Little empirical research has been conducted examining this new population of non-traditional students\' ability to complete their goals when selecting to attend community college, especially in the state of Virginia (Sorey, 2006). Through quantitative methodology, utilizing a cross-sectional design, the purpose of this study was to identify non-academic social and emotional factors that are related to the ability of nontraditional<br />students to persist towards their academic goals within the Virginia Community College System (VCCS). This study included a sample of 1694 students. Their responses to an<br />electronic survey questionnaire of non-traditional students within the VCCS were analyzed to provide descriptive data, correlations, and mean differences. The findings indicate that<br />participants in this study are dealing with multiple non-academic social and emotional factors<br />that may require readjustment in their lives. Further participants in this study perceived<br />themselves as being stressed. Finally, 12.9% of participants endorsed a moderate level of<br />psychological distress and 4.2% of participants endorsed a serious level of psychological distress. The positive correlation between perceived stress and psychological distress supports the need of additional resources, for non-traditional students at the community college level within the Commonwealth of Virginia. / Ph. D.

The purpose of the study was to identify factors that affect whether or not students persist in completion of the GED. Exploration of characteristics of participants that do/do not persist and obtain their GED not only assists the high school dropout, potential GED recipient, and GED program staff, but also society as a whole. More information was needed in order to effectively address issues that adversely affect students enrolled in GED programs at rural community colleges. Therefore, examination of the GED program’s student database contributed in finding factors that both help and impede student success. Factors identified were investigated in an effort to assist in the retention of future participants in the GED program. The subjects of this study consisted of 976 students enrolled in the GED program at a rural community college. The data utilized were archived data, so there was no direct contact with subjects. The data were provided by the GED staff via charts and spreadsheets of student files and records (i.e. demographic sheet information, entry tests-locator test or TABE test, pre-GED testing, exit tests-GED, etc.). A discriminant function analysis was utilized in this study. This was done by weighting the variables and combining them into discriminant functions that separate the groups maximally. The discriminating variables were considered as predictor variables and the group membership variables were considered as dummy criterion variables. Also, a quantitative, non-experimental design was employed to show the direction and magnitude of the relationships between independent variables. The essential features of the design were the abilities to find associations, relate variables, and make predictions. The variables of age, race, gender, employment, public assistance, rural, single parent, and entry/exit levels significantly discriminated into the following groups at a 59.5% rate of accuracy: (1) GED completion, (2) GED continuation, and (3) GED dropouts. Also, age, race, gender, entry level, and rural had a significant impact on persistence/GED completion. With respect to age, it was revealed that older participants were more apt to persist and complete the GED program. White and black participants completed at higher rates than Asian and Hispanic participants. While males completed at higher rates than females. Participants with higher entry levels (4, 5, and 6) completed the program at higher rates. The majority of rural participants completed the GED program.

Graduate student persistence rarely has been studied, yet it is a very important issue for many higher education constituents—including senior administrators, academic deans, faculty members, students, and families. In light of an alarming statistic that approximately 50% of all graduate students fail to complete their degree, there have been few studies to examine this phenomenon and no new models to explain the relationship between factors that influence graduate student persistence. This dissertation examined persistence by graduate students to degree using data from the National Center for Education Statistics' Baccalaureate and Beyond (B&B:93/97) Longitudinal Survey. First, I proposed a logical model of graduate student persistence using economic, academic, and non-academic variables. Then, I tested the model's ability to predict graduate student persistence to degree. Analyses were conducted to answer the following questions: 1. Does more than money matter in predicting graduate student persistence? 2. To what extent do economic, academic and non-academic factors included in the integrated model predict graduate student persistence? a) Does this differ by graduate student status (e.g., master's and doctoral)? If so, how? 3. Using the integrated model, does the likelihood of persisting in graduate school vary by race/ethnicity? If so, how? a) How do student aid and undergraduate debt influence the observed racial/ethnic group differences in persistence? The results of this study suggest that more than money matters when predicting graduate student persistence. The integrate model of graduate student persistence, developed for this study, is statistically significantly better at predicting graduate student persistence than a model that only includes economic factors. The integrated model tested to be most fit for predicting persistence among doctoral students. And, finally, using the model, the likelihood of persisting in graduate school varies by race/ethnicity. Student aid tends to improve one's chances of persisting in graduate school while undergraduate debt is associated with failing to persist in graduate school. / Ph. D.

This study identifies and discusses the academic activities and support services that second-year-engineering students perceived as having impacted their freshman year academic performance. Guided by Astin's (1984) student involvement theory, this investigation involved a total of 34 participants, and was conducted at a large land-grant university in the southeastern United States during the spring semester of the 1998/99 academic year. The following questions were addressed by this study: (1) Which academic activities do students consider as important to their academic performance? (2) Which academic support services do students consider as important to their academic performance? (3) Are there academic performance level-related differences in students' perceptions of the impact of various academic activities in which they are involved, relative to their academic performance? (4) Are there academic performance level-related differences in students' perceptions of impact of the academic support services they use, relative to their academic performance? (5) Are there gender-related differences in students' perceptions of the impact of various academic activities in which they are involved, relative to their academic performance? (6) Are there gender-related differences in students' perceptions of impact of the academic support services they use, relative to their academic performance? (7) Are there race-related differences in students' perceptions of the impact of various academic activities in which they are involved, relative to their academic performance? (8) Are there race-related differences in students' perceptions of impact of the academic support services they use, relative to their academic performance? The data for this study were gathered from 9 focus group interviews and from an accompanying open-ended questionnaire. The 34 participants were divided into groups according to their academic performance levels, gender and race. There were six unsuccessful academic performers with below 2.00 GPAs; 12 low academic performers with GPAs below 2.7 but not less than 2.00; and 14 high academic performers with GPAs of 2.7 and above. The racial and gender composition was: 25 White students, 9 Black students; and equal numbers of males and females (17 each). The criteria for participation were being a second-year, full-time student enrolled in the 1998/99 academic year. Data were analyzed through content analysis, constant comparative data analysis and supplemented by NUD*IST. The resulting findings demonstrate a link between academic involvement activities and academic performance. The academic involvement factors that students perceived as either positively or negatively impacting their freshman year academic performance were identified and categorized into three general themes: (1) effort and involvement, (2) peer interaction and (3) faculty interaction. Effort and involvement factors refer to the specific learning activities implemented and the academic support services students used during the freshman year. Peer interaction factors are the relationships and contacts with fellow students that were perceived as impacting academic performance. Faculty interaction refers to a student's contact with professors inside and outside of the classroom and the perceived impact of these interactions on academic performance. The critical factors identified for success in engineering include doing homework and completing assignments, making good use of one's time, using supportive programmatic resources, and receiving academic support from interacting with peers and faculty. Students who expend effort in these areas are more likely to perform at a higher academic performance level than those who do not. / Ph. D.