La capacité de Brucella suis, un microorganisme strictement aérobique, a s'adapter aux taux d'oxygène faible est un processus essentiel pour la virulence et la persistance bactérienne. Le manque d'oxygène est une condition hostile à laquelle les bactéries sont confrontées lors de la pénétration de l'hôte et pour établir leur niche replicative et la phase de persistance. Cette bactérie possède plusieurs mécanismes par laquelle elle s'adapte à cette condition. Elle peut utiliser un régulateur transcriptionel de la famille de FnrN dépendant de l'oxygène, deux cytochromes oxydases de haute affinité pour l'oxygène et une voie complète de denitrification pour résister au manque d'oxygène. Ce travail a démontré que la respiration oxydative et la denitrification peuvent être simultanément utilisés par B. suis sous microaerobiosis. RegBA, un système à deux composants chez B. suis, a été aussi identifié nécessaire dans l'adaptation bactérienne au manque d'oxygène. Ce dernier a été démontré à coordonner le contrôle des systèmes respiratoires précédemment évoqués. Un schéma de régulation global chez B. suis des voies respiratoires par le régulateur transcriptionel RegA a été suggéré : lors de la variation de l'état redox, la cytochrome bd oxidase jouerait un rôle dans la transmission d'un signal à RegB le senseur de la histidine kinase. De plus, RegA a été identifié essentiel pour la persistance de B. suis in vivo chez la souris dans les organes avec des teneurs faible en oxygène. RegA est supposé être impliqué dans l'installation de la phase de persistance bactérienne durant l'infection chronique. Cette étude a aussi identifié le rôle potentiel de RegA dans la régulation de nombreux gènes impliqués durant la phase de persistance. En utilisant une analyse transcriptomique, comparant les taux d'hybridation chez les souches sauvage et muté dans un modèle in vitro qui imite les conditions d'une infection chronique correspondant a un manque de nutriment et d'oxygène, 447 gènes avec un taux d'hybridation ≥ 2, ont été détectés réguler par RegA. Chez la souche sauvage, 45% et 55 % des gènes étaient régulés et réprimés par RegA chez la souche sauvage, respectivement. 14% des résultats du transcriptome a été choisi pour la validation génétique par RT-qPCR. RegA induit l'expression de gènes impliqués dans le métabolisme d'énergie y compris des gènes de la respiration oxidative, ce qui confirme qu'il interagit dans l'adaptation bactérienne au manque d'oxygène. RegA réprime des gènes impliqués dans la réplication d'ADN, la biogenèse de l'enveloppe et la division cellulaire, de même certains gènes dans le métabolisme d'énergie, ce qui suggère son effet sur la multiplication et l'adaptation bactérienne à l'hypoxie qui existe durant la phase de persistance. RegA a été démontré a réprimer les facteurs de virulence l'operon virB ainsi que son régulateur VjbR. De plus, cette étude a évalué le rôle de deux gènes BR1614 et BR1510 régulés par RegA et impliqués dans le métabolisme des acides gras. Dans les expériences in vivo chez la souris ont démontré que les deux gènes sont essentiels pour la survie, la multiplication et la persistance bactérienne. En conclusion, RegA régule, directement et indirectement, l'expression de gènes qui codent pour la traduction, la transcription, la production d'énergie et la conversion, la réparation d'ADN et de protéine. Ces résultats suggèrent un rôle majeur pour RegA dans la persistance bactérienne pendant la brucellose. 12% du génome de B. suis est sous le contrôle de RegA ce qui indique qu'il est un régulateur global comme son PrrA d'homologue dans Rhodobacter sphearoides. / The capacity of Brucella suis, a strictly aerobic microorganisms, to adapt to low oxygen level is of high importance as it is a required and an essential process for bacterial establishment of virulence and persistence. Oxygen deficiency is a hostile condition to which bacteria are faced when they penetrate the host and reach their replicative niche as well as the persistence phase. This bacterium possesses several mechanisms that answer remarkably to this condition. It can use an oxygen-dependent transcriptional regulator of the FnrN family, two high-oxygen-affinity terminal oxidases, and a complete denitrification pathway to resist various conditions of oxygen deficiency. This work has demonstrated that the oxidative respiration and denitrification can be simultaneously used by B. suis under microaerobiosis. RegBA, a two component systems in B. suis, was also identified to be necessary in bacterial adaptation to oxygen deficiency as it was demonstrated to coordinate the control of the respiratory systems mentioned previously. A scheme for global regulation of B. suis respiratory pathways by the transcriptional regulator RegA was suggested: under redox variation, the cytochrome bd ubiquinol oxidase would play a role in the transmission of a signal to the histidine sensor kinase RegB. RegA in addition was found to be essential for B. suis persistence in vivo in mice within low oxygenated organs. RegA is thus assumed to be involved in the establishment of bacterial persistence during chronic infections. This study also investigated the potential control of RegA in the regulation of numerous genes during the persistence phase. By using a microarray assay comparing wild-type and ∆regA mutant strains, in an in vitro model that mimic the conditions of a chronic infection corresponding to nutrient and oxygen deficiency, 447 genes with a cutoff of the level of hybridization intensities ≥2, were detected regulated by RegA. In the wild-type strain, 45% and 55 % of the genes were up-regulated and down-regulated in wildtype strain, respectively. 14% of the microarray results were selected for genetic validation by RT-qPCR. RegA induced the expression of some genes involved in energy metabolism including the oxidative respiratory genes confirming that it interacts in bacterial adaptation to oxygen deficiency. RegA down-regulated genes involved in DNA replication, cellular division cell envelope biogenesis as well as certain genes in energy metabolism suggesting its impact on bacterial multiplication and adaptation to hypoxia as it enters into the persistence phase. RegA was also found to down-regulate virulence factors such as the virB operon as well as its regulator VjbR. Moreover, this study evaluated the role of two genes BR1614 and BR1510 regulated by RegA and found implicated in fatty acid metabolism. In vivo experiments in mice demonstrated that both genes are required for bacterial survival, multiplication and persistence. In conclusion, RegA was found to regulate, directly and indirectly, the expression of genes that encode for functions in translation, general transcription, energy production and conversion, repair of DNA and protein which represent its high importance and major role in bacterial persistence during brucellosis. 12% of the genome of B. suis is under the control of RegA which makes it a global regulator such as his homologue PrrA in Rhodobacter sphearoides.

Primarily using data from the 2010 European Social Survey, we analyze intergenerational educational persistence in 20 European countries, studying cross-country and cross-cluster differences in intergenerational mobility; the role of gender in determining educational persistence across generations; and changes in the degree of intergenerational persistence over time. We find that persistence is highest in the Southern and Eastern European countries, and lowest in the Nordic countries. While intergenerational persistence in the Nordic and Southern countries has declined over time, it has remained relatively steady in the rest of Europe. Further, we find evidence of differences in intergenerational persistence by gender, with mothers' education being a stronger determinant of daughters' (instead of sons') education and fathers' education a stronger determinant of the education of their sons. Finally we see that for most clusters differences over time are largely driven by increasing mobility for younger women. (authors' abstract) / Series: Department of Economics Working Paper Series

Master of Science / Department of Special Education, Counseling and Student Affairs / Doris Wright Carroll / This study reviews the development of distance education, adult students and specifically looks at the reasons for online course withdrawal. The study specifically examines personal and course-related reasons distance students withdraw from courses. Online students who withdrew from a course were invited to complete a course withdrawal survey to provide additional information about why they withdrew. Students reported balance between coursework and work/family commitments most frequently as the primary reason for course withdrawal. Results indicated that students withdrawing because of work/family reasons have higher intentions of re-enrolling in the future. Faculty and staff response time was another reason reported for course withdrawal. A perceived delay in communication was related to course withdrawal. Results are discussed further and implications are addressed.

The purpose of this dissertation was to capture the voice of the Louisiana Native American students who attend Louisiana institutions of higher education. Native Americans are the least represented minority in colleges. More have entered college in recent years, yet they continue to leave college at a high rate. It is important to understand what motivates Native students to attend college and what keeps them in college. When an understanding of their persistence is achieved, strategies can be implemented to assist others. Research questions that prompted inquiry relate to a Louisiana Native American perspective. All of the research questions ask about the higher education experience and support the primary question: How can the higher education experiences of Native Americans be explained in models of persistence? This dissertation reviews the literature concerning persistence and departure of minority students. Development of ethnic identity is reviewed. The focus of this phenomenological qualitative research study was to examine the experiences of Native Americans during their collegiate journey. Twelve Native American students who attend five institutions of higher education in southern Louisiana were interviewed with open ended questions about their college experiences. Three participants were male and nine were female. Three tribal groups were represented: Choctaw-Apache, Coushatta and the United Houma Nation. Responses have been analyzed using the cultural model presented by Guiffrida (2006) and support the need for a cultural perspective, with the addition of the tribe as an influence. Students were satisfied overall with their experiences. Instances of stereotyping were present that made some students uncomfortable. Intrinsic motivation focused on competency and was frequently coupled with the sense of belonging. Extrinsic motivation came from tribal educational values which provided the cultural capital to pursue a degree. Intended application of the degree was most frequently tied back to the Indian community. Tribal influence was present from intention through to application of the degree. The responses of the participants in this study support a bicultural level and strong enculturation. A model of enculturation is proposed to address the participants' responses.

This study explored how undergraduate library student workers at an urban, 4-year public institution perceived their work experiences in an academic library as contributing to their social and academic integration in college. Tinto's (1993) model on student departure formed the basis for this study where academic and social integration work together to influence institutional commitments ultimately leading to the decision to remain or leave the college. Undergraduate library student workers from various library departments were interviewed and it is from these interviews that a deeper understanding of the phenomenon of an academic library's effect on undergraduate library student workers was gained. The study revealed that the undergraduate library student workers perceived experiencing many socially integrative and academically integrative experiences which they would not have had were they not employed in an academic library. After the data are discussed, the theoretical implications, policy implications, and suggestions for further research are offered.

The purpose of this study was to qualitatively describe the factors that influence the persistence rates of White undergraduate students attending HBCUs from the students' perspectives. Applying Tinto's Model of Student Departure (1975, 1993) as a lens for persistence, the overall aim in this study was to focus on the students' social and academic integration at the institution as well as their institutional experiences at the HBCU as it relates to their decision to persist or depart the HBCU. Through the participants"lived experiences", themes emerged relative to their decision to persist at the institution. The themes were: the influences on relationships with faculty, quality of academic programs, lack of racism from faculty, staff, and peers, involvement in campus activities and organizations, and affordability. The reasons associated with White students' persistence can assist faculty members and administrators at HBCUs in developing and cultivating a culture that is conducive for a positive matriculation and progression process all the way until graduation. Persistence leads to degree completion and no matter the institutional type, all administrators want to increase the number of students graduating from their institutions.

This case study sheds light on successful matriculation practices which emerge from the combination of institutional efforts and student needs. In order to discern successful matriculation data was collected in the form of interviews, observations, and documents at a less selective college with a high rate of retention. Mortimer Adler College possesses unique qualities with respect to curriculum, student population, teaching styles, and student life which affect retention in both positive and negative ways. The institution utilizes a highly structured Great Books curriculum and does not utilize traditional grading and assessment methods. The methods of student socialization are also explored through interviews with faculty and administrators. The findings of this study reveal the qualities of Mortimer Adler College which both support and hinder student success. The study also gives insight to the views of students within this unique institutional setting, focusing on their needs and goals and how their perceptions of the institution impact retention. The review of practices at this institution combined with the perception of the student body allows for the examination of programs and practices employed by Mortimer Adler College which aid in improving and supporting high retention that may also be used at other institutions of higher education. Higher Education, Retention, Persistence, Great Books, Socialization, Faculty Student Relationships

First-year student retention has become a national priority for institutions of higher learning. Since 2004, retention of first-year college students has been on a steady decline. Due to recent the adoption of the Louisiana Granting Resources and Autonomy for Diplomas (GRAD) Act, college administrators in Louisiana are determined to increase first-year student retention, a key performance measure. Of the many factors known to support retention, student-faculty mentoring relationships are known to have a positive impact on college students’ experiences, including increased first-year student retention. However, there is less known about the role of academic advising combined with success coaching in retaining first-year college students. The purpose of this study is to understand first-year college students’ experiences with academic advising and success coaching. By conducting a case study, the researcher further understands the retention of first-year college students to the second year at a comprehensive research public university in Louisiana. The data collected from this study identifies current practices in first-year student retention to inform the current and future programs and services provided on campuses for first-year students.

There is a lack of literature that has investigated the relationships between stereotype threat, impostor phenomenon, and other related constructs on career development, particularly for women in STEM. While various resources (National Science Foundation, 2013; Sax, Kanny, Jacobs, Whang, Weintraub, & Hroch, 2016; US Department of Labor, 2014) have highlighted the gender gap and “leaky pipeline” in STEM, it is important to further investigate and understand why these phenomena occur and continue to persist. In this study, I used a mixed methods approach which used a quantitative SEM analyses and qualitative interview to further examine the paths between chilly climate, impostor phenomenon, stereotype threat, science self-efficacy, fear of failure, fear of success, academic major satisfaction, and persistence in STEM in a sample of undergraduate females. Several hypotheses were formed in order to better understand the mediation effects of these variables upon one another. Stereotype threat was found to be endorsed at a lesser rate than anticipated, while impostor phenomenon was endorsed at a higher rate. Science self-efficacy was also found to play an important role in the predicted relationships among variables, relating to both academic major satisfaction and persistence. These quantitative results were supported by data gathered in qualitative interviews. Implications for research and practice around concerns of impostor phenomenon, stereotype threat, and fears of failure and success are discussed.

The purpose of this study was to investigate differences between native and community college transfer students and identify factors that predicted upper-level biology course grade-point average and final overall grade-point average at a four-year institution in biological sciences. The results of this study indicated four-year institution persistence was not significantly related to gender, high school grade-point average, or ACT composite score. Persistence was significantly related to transfer status; whether the student was a native or community college transfer student with native students persisting at a higher rate at the four-year institution than community college transfer students. Furthermore, ACT composite score, high school grade-point average, final overall grade-point average, and upper level biology course grade-point average were significantly related to transfer status. Multiple regression analyses indicated high school grade-point average and ACT composite score were significantly predictive of upper-level biology course grade-point average while high school grade-point average, ACT composite score, and Pell eligibility were significantly predictive of final overall grade-point average.