Yes / This article examines the entrepreneurial persistence of opportunity-motivated entrepreneurs in Ghana. Specifically, it develops a theoretical model focusing on the relationships among perceived institutional support, entrepreneurial persistence and small venture performance, including how entrepreneurial networks condition the relationship between institutional support and entrepreneurial persistence. Using time-lagged data from 373 opportunity-motivated entrepreneurs leading small ventures in Ghana, we find broad support for our hypotheses. The insights from our study provide an integrative understanding of the relationships among perceived institutional support, entrepreneurial persistence and venture performance in an adverse environment. Theoretical and practical implications are discussed.

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This mixed methods research study used a QUAN-QUAL Model to examine the impact that various factors have on student persistence to graduation in postsecondary education. A documentary research approach was used to collect secondary or existing data from the student information system for first-time full-time freshmen in the Fall 2008 Cohort who graduated within six years. The size of the sample for the quantitative inquiry was 211. A correlational research design was employed to determine if a significant relationship existed between the dependent variables—Persistence to Graduation within Six Years (YEAR) and Final GPA at Time of Degree Completion (FIN GPA)—and the independent variables, Financial Aid Awarded (FINAID), High School GPA (HSGPA), ACT Composite Score (ACT COMP), SAT Combined Score (SAT COMB), First-Year First-Semester GPA (FYFS GPA), First-Year Cumulative GPA (FY GPA), Adjusted Gross Income (AGI), and On-Campus or Off-Campus Housing (ON-OFF CAMP). Descriptive statistical analyses were used to describe, summarize, and interpret the data collected. A case study research approach was used to gain an in-depth understanding into the real-life experiences of a small group of students who did not graduate within six years and who were still persisting toward degree attainment. The Graduation: Survey of Undergraduate Persistence questionnaire was distributed to the participants to gain a holistic understanding of the impact that family, faculty, peers, financial resources, and other environmental influences had on their experiences while persisting toward a college degree. Four questionnaires were completed and returned, followed by three in-depth interviews. The findings from the survey and interviews on the role of financial aid supported the quantitative findings on the relationship between financial aid awarded and persistence to graduation. In the quantitative data analysis, persistence to graduation within six years was significant and positively related to the number of occurrences of financial aid awarded. As the number of financial aid occurrences decreased, the number of years to graduate decreased. Alternatively, an increase in the number of financial aid occurrences resulted in an increase in years to graduate. Postsecondary educational leaders and P-12 educational leaders can utilize the study in forming partnerships to foster collaboration and a “move to action” in preparing students to do college-level course work upon graduating from high school.

Submitted by FERNANDO GASPAROTTO DA SILVA null (fernando.gaspt@hotmail.com) on 2017-09-13T20:17:28Z No. of bitstreams: 1 Gasparotto da Silva, F. - Estrutura e estabilidade de módulos de persistência.pdf: 1909578 bytes, checksum: 4ee1ae3d4306638fe4afbf721614e688 (MD5) / Approved for entry into archive by Luiz Galeffi (luizgaleffi@gmail.com) on 2017-09-15T13:38:44Z (GMT) No. of bitstreams: 1 silva_fg_me_sjrp.pdf: 1909578 bytes, checksum: 4ee1ae3d4306638fe4afbf721614e688 (MD5) / Made available in DSpace on 2017-09-15T13:38:44Z (GMT). No. of bitstreams: 1 silva_fg_me_sjrp.pdf: 1909578 bytes, checksum: 4ee1ae3d4306638fe4afbf721614e688 (MD5) Previous issue date: 2017-08-14 / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / O intuito deste trabalho é de integrar os aspectos aplicado e teórico da Homologia Persistente, uma ferramenta popular da Topological Data Analysis (TDA). Para isso, são apresentados e demonstrados os resultados fundamentais da teoria embasada na topologia algébrica que permitem o desenvolvimento de algoritmos e paradigmas computacionais para obter diagramas de persistência. Dessa forma, iniciaremos explorando como decodificar as informações contidas em um módulo de persistência, entendendo os conceitos de multiconjuntos, módulos de persistência e cálculos Quiver. Em seguida, o caminho contrário será explorado, onde os dados são codificados em diagramas de persistência a fim de extrair suas características topológicas, aprofundando os conceitos de funções de Morse, Homologia Persistente, diagramas de persistência, dualidade e simetria, bem como estabilidade. Por último, encerramos demonstrando duas possíveis aplicações da teoria no âmbito computacional no campo da Biologia. / The goal of this work is to integrate applied and theoretical aspects of Persistence Homology, a popular tool in Topological Data Analysis (TDA). For this, we present and prove fundamental theoretical results based on algebraic topology, which allow us to develop algorithms and computational paradigms to obtain persistence diagrams. In this way, we start exploring how to decode the information contained in a persistence module, understanding the concepts of multiset, persistence modules and Quiver alculations. Then, the opposite path will be explored, where the data are encoded in persistence diagrams in order to extract their topological characteristics, going deep into the concepts of Morse functions, persistent homology, persistence diagrams, duality and symmetry, as well as stability. Finally, we conclude with two possible applications, one from computational theory, and the second one in the field of biology. / CNPq: 135622/2015-8

Human cytomegalovirus (HCMV) coexists indefinitely in infected individuals through a poorly characterized latent infection in hematopoietic cells. We previously demonstrated a requirement for UL138 in promoting a latent infection in CD34+ hematopoietic progenitor cells (HPCs). UL138 is encoded on three co-terminal transcripts of, 1.7-, 2.7-, and 3.6-kilobases. Interestingly, the UL138 protein product (pUL138) is necessary but insufficient for HCMV latency. The mechanisms by which pUL138 contributes to the latent infection are unknown, however other viral determinants are required for the latent infection. We identified 3 novel proteins pUL133, pUL135, and pUL136 encoded on the UL138 transcripts. Similar to pUL138, pUL133, pUL135, and pUL136 are Golgi localized type I transmembrane proteins expressed with early kinetics during productive infection. We have named these UL138 related proteins, CLAMPs for HCMV Latency Associated Membrane Proteins. Through a systematic immunoprecipitation analysis, we identified interactions between the CLAMPs and characterized an interaction between pUL133 and pUL138. Further, we mapped the interacting region to a specific domain in the C-terminal, cytosolic tail of pUL138. Additionally, we show that each of the CLAMPs has the ability to self-associate. The localization of the CLAMPs to the Golgi suggests that these proteins likely promote HCMV latency through a novel mechanism involving Golgi functions. Additionally, through a Y2H screen of a human bone marrow cDNA library, we identified an interaction between pUL138 and the heat shock protein 40 (Hsp40) variant MRJ. We confirmed this interaction in mammalian cells and mapped the pUL138 region responsible for this interaction to a domain in the cytoplasmic tail of pUL138. We also demonstrated additional MRJ interactions with pUL133 and pUL136. Importantly, pUL138 specifically interacts with Hsp40 variants during productive infection. Preliminary data suggest that HCMV infection up regulates MRJ mRNA expression and recombinant viruses lacking pUL138 show a disproportionate up regulation of MRJ. pUL138 is the first HCMV protein demonstrated to promote a latent infection. While the mechanisms by which pUL138 contributes to latency remain unknown, the interaction with other CLAMPs and with MRJ, suggest that pUL138 may cooperate with other CLAMPs to modulate the cellular stress response at the Golgi to promote HCMV latency.

This qualitative study examined the experiences of 20 African American men who graduated from predominately White institutions in one mid-Atlantic state between the years of 2001 and 2011 with doctoral degrees in Education or in a Humanities and Sciences field. Interviews were conducted to gather the lived experiences of the African American men in their own voices. The study addressed the following research questions: 1. Why do African American men persist to doctoral degree completion? 2. How do African American men perceive their doctoral student experience? A descriptive model that presents the internal and external factors revealed in the study is provided. Five main internal factors that contribute to the persistence of African American men in doctoral programs: personal refinement, academic refinement, professional refinement, motivation, and effective coping mechanisms were revealed. Three major external factors, support systems, positive relationships with the advisor/chair and committee, and financial support. In addition, the impact of the participants’ racial identity was explored and yielded both negative and positive effects on the doctoral student experience. Based upon the results, recommendations are offered for universities and departments, advisors and faculty, and future and current African American male doctoral students to aid them in persistence to degree completion.

The presence of volatile methylsiloxanes (VMS) in the environment has raised concerns among environmental chemists and regulators about their persistence and the risks they may pose to the environment. This thesis explores the partitioning and persistence of VMS in aquatic environments. In Paper I, we reported new measurements of the organic carbon/water (KOC) and dissolved organic carbon/water (KDOC) partition ratios of three cyclic volatile methylsiloxanes (cVMS) and of three polychlorinated biphenyls (PCBs), which were used as reference chemicals. We combined new measurements with existing data to construct polyparameter linear free energy relationships (PP-LFER) that describe the KOC and KDOC of diverse sets of chemicals. The findings suggest that cVMS do not conform to single-parameter regressions that relate the chemicals’ KOC to their octanol/water partition ratio (KOW). PP-LFERs can accurately describe the KOC and KDOC of cVMS but only if cVMS are included in their training sets. In Paper II, we studied the effect of salinity on the KOC and KDOC of three cVMS, two linear volatile methylsiloxanes (lVMS) and three PCBs. We also evaluated the predictive power of the PP-LFERs constructed in Paper I by testing them on the newly measured KOC values of lVMS. The KOC and KDOC increased with increasing salinities similarly to those of the PCBs. PP-LFERs that were trained with datasets that included siloxanes could predict the KOC and KDOC of other siloxanes more accurately than PP-LFERs without siloxanes in the training set. In Paper III, we evaluated the effect of temperature on the KOC of VMS and we compared our measurements of the enthalpy of sorption to organic carbon (ΔHOC) to existing measurements of the enthalpy of phase change between octanol and water (ΔHOW). Due to the scarcity of ΔHOC data in the literature it is common practice in modeling calculations to use ΔHOW instead when correcting for temperature changes. The KOC of cVMS increased with decreasing temperatures. Moreover, our results indicate that ΔHOC and ΔHOW may be intrinsically different and hence replacing ΔHOC with ΔHOW in modeling calculations could lead to substantial errors, especially for VMS. In Paper IV, we explored the environmental fate of VMS in aquatic environments using multimedia models. In particular, we assessed the differences that may occur in calculations of persistence due to (i) the reported KOC measurements of VMS differing by one log unit (ii) the influence of salinity on KOC, and (iii) the differences in the reported ΔHOC and ΔHOW measurements of VMS. The calculated residence times for decamethylcyclopentasiloxane (D5) in a site-specific scenario for a Norwegian fjord receiving siloxanes in wastewater ranged from 200 to 1000 days, and demonstrated that the selection of KOC values can result in substantially different calculated persistence. Future partitioning measurements of VMS in the real environment and mass-balance modeling studies in aquatic environments combined with field measurements could help us to deepen our understanding about their persistence and to assess the risks VMS may pose to the environment. / <p>At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 1: Manuscript. Paper 3: Submitted.</p>

Research has suggested that persistence in the face of challenges plays an important role in learning. However, recent work on wheel-spinning—a type of unproductive persistence where students spend too much time struggling without achieving mastery of skills—has shown that not all persistence is uniformly beneficial for learning. For this reason, Study 1 used educational data-mining techniques to determine key differences between the behaviors associated with productive persistence and wheel-spinning in ASSISTments, an online math learning platform. This study’s results indicated that three features differentiated between these two modes of persistence: the number of hints requested in any problem, the number of bottom-out hints in the last eight problems, and the variation in the delay between solving problems of the same skill. These findings suggested that focusing on number of hints can provide insight into which students are struggling, and encouraging students to engage in longer delays between problem solving is likely helpful to reduce their wheel-spinning. Using the same definition of productive persistence in Study 1, Study 2 attempted to investigate the relationship between productive persistence and grit using Duckworth and Quinn’s (2009) Short Grit Scale. Correlational results showed that the two constructs were not significantly correlated with each other, providing implications for synthesizing literature on student persistence across computer-based learning environments and traditional classrooms.

Chronic infections are often attributed to bacterial biofilms. These biofilms are extremely tolerant to antimicrobial treatment due to the presence of dormant persister cells. Whilst a number of persister genes and pathways have been identified, it is likely that others remain. Investigating persistence of S. Typhimurium was therefore undertaken. A csp null mutant of Salmonella enterica sv. Typhimurium, lacking all six cold shock protein (CspA) paralogues was previously constructed (Hutchinson 2005). At 10°C, this strain is unable to divide, but remains viable for several weeks. However it remains capable of growth at 37°C and thus is conditionally dormant. Using this strain, the link between dormancy and persistence was investigated. Treatment of stationary phase planktonic cultures with fluoroquinolones revealed persister cells in SL1344. In contrast the csp null mutant was completely eliminated by treatment at 37°C; this could be prevented by cspC or cspE expression, implicating a role for cspA paralogues in persistence. Cold shock (10°C) substantially increased persister levels, although csp null cultures remained hypersensitive. Chloramphenicol pre-treatment also reduced elimination of the csp null mutant, linking translation with the persister phenotype. Mutations in 5 genes affecting chromosomal structure and function were investigated, 3 of which (hns, hfq, rpoS) were found to reduce persister levels, suggesting a possible role for DNA supercoiling in persistence. Plasmid topologies in the csp null mutant were highly supercoiled compared to SL1344, a phenotype prevented by cspC or cspE expression. Altered supercoiling is therefore proposed as a mechanism for fluoroquinolone sensitivity in the csp null mutant. Persister levels were also characterised in biofilms of SL1344 and the csp null mutant. In contrast to stationary phase planktonic cultures, the CspA paralogues did not appear to play a role in biofilm persistence under the experimental conditions tested. However, the study revealed a novel role for CspA paralogues in pellicle formation at the air-liquid interface. A plasmid library was used to identify chromosomal regions capable of rescuing the planktonic persister phenotype of the csp null mutant. One region which delayed fluoroquinolone elimination of the csp null mutant, contained components of the hpa gene cluster, replicated in 11 isolates. This locus is involved in hydroxyphenylacetate (HPA) catabolism, indicating a possible role of cellular metabolism in the persistence. Overall this study has revealed novel information about antibiotic persistence in S. Typhimurium and the involvement of the CspA paralogues. These results provide an important foundation for further investigations and contribute towards knowledge of the complex processes of dormancy, persistence and biofilm formation in bacteria.