Ultra-broadband phase-matching ultrashort-laser-pulse measurement techniques

In the past several decades the technology for the creation and use of ultrashort pulses has progressed tremendously. Now, it is possible to generate laser pulses as short as a few femtoseconds in duration, and such pulses have been used for a wide range of applications. In addition, the means of measuring these pulses has progressed so rapidly. However, despite recent great advances in ultrashort-pulse measurement techniques, much remains to be done. In particular, pulse-measurement devices have relatively small wavelength-tuning ranges, and the phase-match is problematic for the pulses with a wide bandwidth such as supercontinuum. In this thesis, I will demonstrate a new pulse measurement technique which can phase-match ultra-broad bandwidth of super-continuum using transient grating frequency-resolved-optical-gating (TG FROG). Also, I will demonstrate a simplified device which can measure the UV ultra-short pulse using transient grating process, one of the third-order nonlinearity and can cover from UV to IR with the same arrangement.Ph.D.Committee Chair: Trebino, Rick; Committee Member: Adibi, Ali; Committee Member: Buck, John; Committee Member: First, Phillip; Committee Member: Raman, Chandr

Access Affordance of Mobile Technology in e-Commerce: Change of Purchase Time Dispersion

The portability of a mobile device and the ubiquity of mobile Internet provide e-market users with more opportunities of access to e-commerce sites throughout a day. In this paper, we examine the access affordance of mobile technologies by analyzing the changes in purchase time dispersion of e-marketplace users after their adoption of mobile channel. By analyzing a large archival dataset including transactions in the mobile and online channels, we find that (1) a user’s purchase time becomes more dispersed throughout a day after the mobile channel adoption, and (2) the impact of the mobile channel adoption on the purchase time dispersion is significantly different across different user groups. These findings present strong empirical evidences of access affordance of the mobile channel and how the affordance is realized across e-market users

TET3 plays a critical role in white adipose development and diet-induced remodeling

Maintaining healthy adipose tissue is crucial for metabolic health, requiring a deeper understanding of adipocyte development and response to high-calorie diets. This study highlights the importance of TET3 during white adipose tissue (WAT) development and expansion. Selective depletion of Tet3 in adipose precursor cells (APCs) reduces adipogenesis, protects against diet-induced adipose expansion, and enhances whole-body metabolism. Transcriptomic analysis of wild-type and Tet3 knockout (KO) APCs unveiled TET3 target genes, including Pparg and several genes linked to the extracellular matrix, pivotal for adipogenesis and remodeling. DNA methylation profiling and functional studies underscore the importance of DNA demethylation in gene regulation. Remarkably, targeted DNA demethylation at the Pparg promoter restored its transcription. In conclusion, TET3 significantly governs adipogenesis and diet-induced adipose expansion by regulating key target genes in APCs

Impaired Inflammatory Responses in Murine Lrrk2-Knockdown Brain Microglia

LRRK2, a Parkinson's disease associated gene, is highly expressed in microglia in addition to neurons; however, its function in microglia has not been evaluated. Using Lrrk2 knockdown (Lrrk2-KD) murine microglia prepared by lentiviral-mediated transfer of Lrrk2-specific small inhibitory hairpin RNA (shRNA), we found that Lrrk2 deficiency attenuated lipopolysaccharide (LPS)-induced mRNA and/or protein expression of inducible nitric oxide synthase, TNF-α, IL-1β and IL-6. LPS-induced phosphorylation of p38 mitogen-activated protein kinase and stimulation of NF-κB-responsive luciferase reporter activity was also decreased in Lrrk2-KD cells. Interestingly, the decrease in NF-κB transcriptional activity measured by luciferase assays appeared to reflect increased binding of the inhibitory NF-κB homodimer, p50/p50, to DNA. In LPS-responsive HEK293T cells, overexpression of the human LRRK2 pathologic, kinase-active mutant G2019S increased basal and LPS-induced levels of phosphorylated p38 and JNK, whereas wild-type and other pathologic (R1441C and G2385R) or artificial kinase-dead (D1994A) LRRK2 mutants either enhanced or did not change basal and LPS-induced p38 and JNK phosphorylation levels. However, wild-type LRRK2 and all LRRK2 mutant variants equally enhanced NF-κB transcriptional activity. Taken together, these results suggest that LRRK2 is a positive regulator of inflammation in murine microglia, and LRRK2 mutations may alter the microenvironment of the brain to favor neuroinflammation

Sense of co-accomplishment in collaborative work as threshold in establishing a sense of community in an online course

textThis study explored students’ sense of community in an online collaborative learning environment, focusing on the factors influencing students’ sense of community, the relationships among the factors, and the influences of a sense of community. The setting of this study was a graduate-level online course on Computer Supported Collaborative Learning in which all course activities were conducted collaboratively through online communications. Data were collected from multiple sources including participants’ electronic messages posted in public areas of the computer conferencing system, transcripts of online chats, interviews with the participants, participants’ written reflections on their learning process, and an instrument measuring students’ sense of community. Data were analyzed using the coding procedures for developing grounded theory proposed by Strauss and Corbin (1998). Results of the data analysis indicated that students established their sense of community by experiencing a sense of coaccomplishment through collaboration. Results also indicated that the factors influencing students’ sense of community related to three dimensions: group interaction, course context, and individual differences. Students’ sense of community was influenced primarily by the outcomes of interactions with group members, such as group members’ behaviors showing consideration for others, responding to their contributions, and contributing to the group collaboration. Factors related to the course context, such as the collaborative nature of the course, the technology used for the course, and the instructor’s role, influenced students’ sense of community by either facilitating or interfering with the group interactions. In addition, some factors resulting from individual differences in backgrounds and characteristics, such as personalities and attitudes toward collaborative learning, were critical for students to develop a sense of community. Once a sense of community was established, students developed a sense of camaraderie with their group members, felt more comfortable in working together, developed a greater sense of responsibility, and developed trust in their group members. The consequences of a sense of community, in turn, influenced the factors that promoted a sense of community when the students engaged in the next collaborative task.Curriculum and Instructio

Total synthesis of (+)-tedanolide

This dissertation describes the synthetic studies culminating in the Smith total synthesis of (+)-tedanolide, a potent cytotoxic marine macrolide. Chapter one provides an introduction to the tedanolide family of natural products. Specifically, the isolation, structure elucidation, and biological activity of the tedanolides are discussed. Furthermore, a review of relevant synthetic work by other groups towards the tedanolides is summarized.* Chapter two provides a critical analysis of our synthetic approach to the (+)-tedanolide (1) and describes the synthesis of two major subtargets: (1) the common advanced C(1)-C(11) dithiane (−)- 26 for both (+)-tedanolide (1) and (+)-13-deoxytedanolide (2), via the iterative Evans syn-aldol reaction and stereocontrolled union of fragment (+)-21 and bidirectional linchpin (−)-22; (2) the C(12)-C(23) epoxide (+)- 178 via the efficient and highly convergent union of fragment (+)- 220 and (+)-221.* Chapter three describes the construction of the carbon framework of tedanolide (1) via the union of the dithiane linchpin (−)-26 with the requisite epoxide (+)-178, and the completion of the total synthesis of (+)-tedanolide (1).* *Please refer to dissertation for diagrams

Total synthesis of (+)-tedanolide

This dissertation describes the synthetic studies culminating in the Smith total synthesis of (+)-tedanolide, a potent cytotoxic marine macrolide. Chapter one provides an introduction to the tedanolide family of natural products. Specifically, the isolation, structure elucidation, and biological activity of the tedanolides are discussed. Furthermore, a review of relevant synthetic work by other groups towards the tedanolides is summarized.* Chapter two provides a critical analysis of our synthetic approach to the (+)-tedanolide (1) and describes the synthesis of two major subtargets: (1) the common advanced C(1)-C(11) dithiane (−)- 26 for both (+)-tedanolide (1) and (+)-13-deoxytedanolide (2), via the iterative Evans syn-aldol reaction and stereocontrolled union of fragment (+)-21 and bidirectional linchpin (−)-22; (2) the C(12)-C(23) epoxide (+)- 178 via the efficient and highly convergent union of fragment (+)- 220 and (+)-221.* Chapter three describes the construction of the carbon framework of tedanolide (1) via the union of the dithiane linchpin (−)-26 with the requisite epoxide (+)-178, and the completion of the total synthesis of (+)-tedanolide (1).* *Please refer to dissertation for diagrams

Interdisciplinary perspectives on narcissistic personality traits of preachers in the South Korean context

Thesis (MTh)--Stellenbosch University, 2020.ENGLISH ABSTRACT: Preaching does not exclude the unique qualities of individual preachers, but rather actively reflects them. If a preacher suffers from problems that arise from his/her personality, the problems will also have an effect on the preaching. Since preaching is not just a transfer of knowledge, it is important for the preacher to have a relational authenticity with other elements of the preaching: God, the text, the congregation, and the preacher him/herself. Hence, focusing on the preacher’s narcissistic personality associated with this relational authenticity, this research hypothesizes that the preacher’s narcissistic personality or behavior has negative effects on the preaching. This research as an interdisciplinary study between psychology and homiletics for the understanding the preacher’s narcissistic issue in the South Korean context constitutes three parts. Firstly, the historical review of narcissism in three psychological fields - clinical theories, personality/society psychology, and psychiatry - is conducted for the comprehensive understanding of the concept of narcissism. Secondly, it examined some cultural factors that have considerable relevance to the preacher’s narcissistic issues in the South Korean context. Lastly, drawing on the perspective of Kohut’s self psychology and Cilliers’ understanding of preaching as a theological integration of the four voices – the voices of God, the text, the preacher, and the congregation – this research analyzed the (mainly negative) influences of a preacher’s narcissistic personality on the preaching.AFRIKAANSE OPSOMMING: Prediking sluit nie die unieke eienskappe van individuele predikers uit nie, maar weerspieël dit eerder aktief. Indien 'n prediker probleme ondervind wat vanuit sy/haar persoonlikheid afkomstig is, sal die probleme ook 'n invloed op die prediking hê. Aangesien prediking nie net 'n oordrag van kennis is nie, is dit belangrik dat die prediker relasionele egtheid handhaaf met betrekking tot ander elemente van die prediking: met God, die teks, die gemeente en die prediker self. As gevolg van die fokus op die narcistiese kwessies van die prediker, dui hierdie navorsing dus daarop dat die narcistiese persoonlikheid of gedrag van die prediker negatiewe gevolge vir die prediking inhou. Die navorsing, wat uit drie dele bestaan, behels 'n interdissiplinêre studie tussen sielkunde en homiletiek om die narcistiese aangeleentheid van die prediker in die Suid-Koreaanse konteks te verstaan. Die drie afdelings daarvan voorsien ‘n historiese oorsig van narcisme in drie psigologiese areas. Eerstens word die historiese oorsig van narcisme binne drie sielkundige terreine – kliniese teorieë, persoonlikheids-/ samelewingspsigologie en psigiatrie – onderneem vir ‘n omvattende begrip van die konsep van narcisme. Tweedens word 'n aantal kulturele faktore wat aansienlik relevant is vir die narcistiese kwessies van die prediker in die Suid-Koreaanse konteks ondersoek. Laastens word die (hoofsaaklik negatiewe) invloede van die narcistiese persoonlikheid van die prediker op die prediking aan die hand van Kohut se selfpsigologie en Cilliers se begrip van die prediking as 'n teologiese integrasie van vier stemme – van God, die teks, die prediker en die gemeente – geanaliseer.Master

Factors Influencing Learning Satisfaction of Migrant Workers in Korea with E-learning-Based Occupational Safety and Health Education

Background: E-learning-based programs have recently been introduced to the occupational safety and health (OSH) education for migrant workers in Korea. The purpose of this study was to investigate how the factors related to migrant workers' backgrounds and the instructional design affect the migrant workers' satisfaction with e-learning-based OSH education. Methods: The data were collected from the surveys of 300 migrant workers who had participated in an OSH education program. Independent sample t test and one-way analysis of variance were conducted to examine differences in the degree of learning satisfaction using background variables. In addition, correlation analysis and multiple regression analysis were conducted to examine relationships between the instructional design variables and the degree of learning satisfaction. Results: There was no significant difference in the degree of learning satisfaction by gender, age, level of education, number of employees, or type of occupation, except for nationality. Among the instructional design variables, “learning content” (β = 0.344, p < 0.001) affected the degree of learning satisfaction most significantly, followed by “motivation to learn” (β = 0.293, p < 0.001), “interactions with learners and instructors” (β = 0.149, p < 0.01), and “previous experience related to e-learning” (β = 0.095, p < 0.05). “Learning environment” had no significant influence on the degree of learning satisfaction. Conclusion: E-learning-based OSH education for migrant workers may be an effective way to increase their safety knowledge and behavior if the accuracy, credibility, and novelty of learning content; strategies to promote learners' motivation to learn; and interactions with learners and instructors are systematically applied during the development and implementation of e-learning programs

Transit Ridership Evaluation Using Aggregate-Level Causal Analyses of Subway Mode Shares in Seoul, South Korea

Adequate evaluations of transit system efficiency in direct connection with environmental concerns and the economic aspects of the city are critical for development of a better system. This paper presents an evaluation framework by comparing the subway mode shares of 25 districts in Seoul, South Korea. In this effort, causal relationships between the inherent conditions of the district and the resultant mode shares were identified on the basis of regression models with independent variables indicating the system supply level. The expected mode shares from the regression model and the actual shares were then compared as a way to identify districts displaying relatively higher or lower subway mode shares. These processes revealed key influential factors affecting subway mode share and suggest that the system supply level is strongly related to mode share and that ridership increases may be achieved by providing convenient access to stations. The implications of this study are expected to shed light on potential policy actions to improve transit ridership, particularly for those districts with relatively lower levels of ridership