Dissertation Defense Announcements

Candidate Name: Hamad Alsaleh
 March 30, 2022  10:30 AM
Location: https://uncc.zoom.us/j/99864152046

In recent years, social media have dramatically improved the dissemination speed of information, which also includes health misinformation. To date, most of the computational approaches to addressing this problem have focused on detecting and flagging misinformation content. However, the majority of these approaches have overlooked many important aspects of health misinformation, such as the behavior of evidence sources and the sharing decisions of social media users. To address the limitations, this dissertation research develops an evidence-based approach to detecting health misinformation and to intervening user sharing intention on social media sites. This work takes on a new perspective regarding health misinformation by understanding user stance (i.e., for, against, neutral) due to their motivation of influencing others. Moreover, this research investigates arguments that combine both stance and evidence for assessing the credibility of health information for the very first time. Our analysis of evidence distribution in health information tweets shows that 70% of tweets contain source-based evidence, which provides the foundation for proposing an evidence-based approach to misinformation detection. Based on these results, we built argument detection models to identify stance positions within arguments. Our results demonstrate the importance of evidence-based features in identifying the stance within arguments on social media sites. Drawing on the evidentiality theory, information credibility heuristics, and consistency heuristics, we propose a research model that seeks to explain health misinformation detection and sharing behavior with evidence-based interventions. To test the research model, we designed and developed eleven types of evidence-based digital nudges and used them to conduct user experiments. The empirical results demonstrate that our nudge design improves credibility assessment of health misinformation. This dissertation makes several research contributions. First, it extends an evidentiality theory and credibility cognitive heuristics provided by health experts to analyze the types of evidence included in health-related user-generated content Second, it presents an evidence-based schema for categorizing evidence in user-generated content. Third, it uses evidentiality theory as the kernel theory to guide the design of digital nudges. In particular, it illustrates how evidence-based design artifacts can be used to support augmented intelligence for mitigating the spread of health-related misinformation on social media sites. Finally, it combines cognitive heuristics to the design of digital nudges. Specifically, it uses information credibility and consistency heuristics to analyze user-generated content on social media sites. The outcomes of this research have significant implications for augmenting users’ assessment of health information credibility and enabling timely intervention of misinformation on social media sites.

Candidate Name: Taichun Piao
Title: Corporate Finance
 March 25, 2022  2:00 PM
Location: Zoom meeting

I have the following three essays in the dissertation:
1. "Does Executive Compensation Duration Generate Different Risk Incentives? Evidence on Corporate Hedging?" coauthored with Jun Chen and Dolly King.
2. "Putable Bonds, Risk-Shifting Problems, and Information Asymmetry," coauthored with Xinde Zhang and Dolly King.
3. "Shareholder-Creditor Conflict and Hedging Policy: Evidence from Mergers between Lenders and Shareholders," coauthored with Yongqiang Chu, Dolly King, and Chen Shen.

Candidate Name: Boya Jin
Title: Superlens imaging and light concentration in mesoscale photonics: design and implementation
 March 29, 2022  11:30 AM
Location: Grigg 133

Progress in nanofabrication made possible development of metamaterials and nanoplamonics two decades ago. The area of mesoscale photonics where the characteristic dimensions of spherical, pyramidal or other building blocks are on the order of several wavelengths remained relatively less studied. However, the optical properties of such structures are extremely interesting due to their ability to create tightly focused beams, so-called “photonic nanojets”, and to resonantly trap light inside their building blocks. In this dissertation, we focus on two main applications of such structures. It is proposed to use dielectric microcons for concentrating light on photodetector focal plane arrays (FPAs) and it is proposed to use contact high-index dielectric microspheres (also termed ball lenses) for improving resolution in cellphone-based microscopy.
We proposed and developed three designs of silicon (Si) microconical arrays which can be used as light concentrators for integration with FPAs operating in mid-infrared (MWIR) region. Such structures can be fabricated by anisotropic wet etching of Si. The spectral and angular dependencies of power enhancement factors (PEFs) provided by such high-index (n~3.5) Si microcones are calculated using finite-difference time-domain modeling. In addition, we observed and studied resonant trapping of photons inside such microcones which can lead to their applications in multispectral imaging devices with a large angle-of-view (AoV).
It is shown that similar microconical light concentrators formed by low-index materials (n = 1.6) which can be fabricated by Nanoscirbe or by plastic injection molding. It is demonstrated that PEFs ~100 times can be achieved in such structures with optimized geometry. It was demonstrated a good agreement of our numerical modeling results with the experiments performed previously on structures with a suboptimal geometry.
We proposed a novel label-free cellphone microscopy assisted by high index contact ball lenses. Resolution of the cellphones is limited by the pixilation of the images. Previous microoptics-based imaging solutions provided insufficient magnification and suffered from spherical aberrations and pincushion distortion. In our work, it is shown that use of ball lenses with n~2 specially designed to provide maximal magnification values (up to 50 times) allows to reduce the role of pixilation and reach diffraction limited resolution values of ~600 nm based on rigorous resolution quantification criteria. It is demonstrated that dispersion properties of the ball lens material significantly influence the magnification in such cellphone imaging. It is shown a semi-quantitative agreement of observed magnification with a simplified geometrical optics model. We demonstrated imaging of various biomedical samples by using proposed cellphone microscopy. It is shown that it can be used as a compact and inexpensive replacement of conventional microscopes to diagnose diseases such as melanoma in vivo without invasive biopsy.
To extend FoV, we assembled centimeter-scale arrays of ball lenses using either micromanipulation or air suction through microhole arrays obtained by laser burning or micromachining. It was found this technology allows obtaining ordered arrays for sufficiently large (>300 μm) ball lenses, but assembling smaller microspheres can in principle be also achieved in future work. It was demonstrated that such microspherical arrays can be used as: a) superresolution coverslips with wide FoV (after embedding in plastic), and b) retroreflectors with ultranarrow reflection cone and highly dispersive properties.

Candidate Name: Meg Alexandra García
Title: Examining the Relationship of Number of Multiracial Siblings, Sibling Phenotype Similarity, and Sibling Relationship Quality with Multiracial Identity Development
 March 29, 2022  11:00 AM
Location: COED 246 - Please email mgarci48@uncc.edu for Zoom link.

Although the multiracial population is currently the fastest growing racial group in the United States, little remains known about their identity and mental wellness. The purpose of this study was to investigate factors that progress multiracial identity development. More specifically, this study examined the relationship of number of multiracial siblings, sibling phenotype similarity, and sibling relationship quality with the multiracial identity development of multiracial adults. A total sample of 563 multiracial participants were recruited from across the United States and completed an online survey involving self-report questions. The outcome variable of multiracial identity development was measured using the Multiracial Identity Integration Scale. Number of multiracial siblings was measured by a single item on the demographic questionnaire, sibling phenotype similarity was measured by an 11-item scale that the researcher created, and sibling relationship quality was measured by the Lifespan Sibling Relationship Scale. A multiple linear regression analysis and one-way analysis of variance were utilized by the researcher to examine the relationship of the predictor variables with multiracial identity development. The results indicated that none of the predictor variables were found to significantly influence multiracial identity development. Implications of this study include the need for a noticeable increase in research on this identity, counselor trainings and teachings on this population, and the awareness of negative stereotypes about this population still embedded in mental health research and practice. This study provides a starting place for future studies to build upon when investigating multiracial siblings and factors that influence multiracial identity development.

Candidate Name: Jessica Mitchell Cline
 March 29, 2022  2:30 PM
Location: Zoom

To determine how secondary, Math I teachers understand student engagement in the classroom setting by exploring their lived experiences, the researcher utilized a constructivist paradigm to frame the phenomenological multiple case studies of one
southwestern North Carolina school district. The intent of the researcher was to describe the understanding of the phenomenon of classroom engagement from the perspectives of high school Math 1 teachers. The researcher engaged in conversations with a purpose
which is characterized by Burgess (1984) as a conversational dialogue that is achieved through active engagement by the interviewer and interviewee around a relevant issue.
Research regarding engagement began in the early 1980’s. The topic of engagement has become increasingly popular in education and psychological research due to its emphasis on explaining student behaviors (van Uden, Ritzen, & Pieters, 2013). Multiple definitions and variables within the research have emerged in attempts to articulate a single definition of classroom engagement (Azevado, 2015). Yet, a widely agreed upon definition and measurement of engagement still does not exist.
The findings presented emphasize participants’ understanding of the importance of Cooper’s (2011) Classroom Engagement Framework’s “Connective Teaching” as the foundational point of entry to engaging students within the Math 1 classroom setting.
Furthermore, the findings present the unique challenges faced by Math 1 teachers as they teach primarily freshmen who need to learn content as well as skills for success within the Math 1 classroom and in high school.

Candidate Name: Robert Michael Bickmeier
Title: The Development and Validation of a Measure of the Experience of Dirty Work
 April 01, 2022  2:00 PM
Location: Join Zoom Meeting https://uncc.zoom.us/j/96200300568?pwd=cjJCdVowZHplSy81QVNoUytjV0lkQT09

Dirty work is socially constructed as tainted on one or more domains (physical: dangerous, dirty, or associated with death; moral: underhanded or in contradiction to prevailing norms; social: in association with stigmatized others or done in subservience), and it shapes dirty workers’ perceptions and experiences of their identities. The processes through which the perception of taint shapes identities and associated outcomes (e.g., identity ambivalence, isolation) and the effects of the magnitude of dirt are not fully understood. To understand these processes, the present study describes the development of a tool to measure the dirt of dirty work. First,the author developed a series of item to assess the content domain of dirty work based on a literature review supported by open-ended responses describing work perceptions from dirty workers. In the subsequent studies, the author reduced the item pool by a series of exploratory factor analyses (EFA). Then, the author tested the overall model fit across two separate samples via confirmatory factor analysis (CFA) and identified a three-factor model. Finally, the author gathered validity evidence through convergent and discriminatory validity analyses: the pattern of correlations generally provided convergent validity evidence with the respective covariates, and the data tentatively supported the measure’s ability to discriminate among forms of taint by occupation in a one-way MANOVA.

Candidate Name: Christine H. Weiss
Title: Teacher Practices, Beliefs, and Conceptual Understanding of Mathematics: A Phenomenological Case Study of Teachers Instructing Mathematically Gifted and Promising Students
 April 04, 2022  12:30 PM
Location: UNC Charlotte campus

Students in the United States are not achieving in mathematics as indicated on the NAEP (2019) exams and other measurements of student achievement (OECD, 2019; O’Dwyer, Wang, & Shields, 2015; NCES, 2019). Mathematically gifted and promising students are especially impacted by this phenomenon, though it is not exactly known what factors contribute to successful teachers of these students. This phenomenological case study focused on the beliefs, instructional practices, and conceptual understanding of mathematics of five teachers in a public charter school for gifted students. Data sources collected included semi-structured interviews, classroom observations, and questionnaires based on Swan’s (2006) practices and beliefs research with effective mathematics teachers. Two theories of giftedness served as the theoretical lens for this study: Renzulli’s Three-Ring Model (1978) and Gagné’s Differentiated Model of Giftedness and Talent (1985) to better understand these phenomena. Using an interpretive phenomenological analysis several themes emerged in response to each research question. Findings for instructional practices indicated that teachers used both student-centered and teacher-centered practices and consistently utilized differentiated groupings. Additionally, teacher participants believe that gifted students possess both positive traits and challenges and specifically for math, believe that sense-making is key, and math is a subject students should enjoy. Teachers’ conceptual understanding of mathematics is guided by their ongoing practice, the curriculum, and math experiences prior to teaching. These findings indicate the importance of ongoing training and professional development in mathematics and gifted education, as well as the recruitment and retention of teachers who possess a strong conceptual understanding of mathematics, a passion for the subject, and a student-centered approach to teaching.
Keywords: mathematically gifted, instructional practices, beliefs, teachers’ conceptual understanding of mathematics

Candidate Name: Melissa R. Medaugh
 March 25, 2022  1:00 PM
Location: Zoom: https://uncc.zoom.us/j/91753379241?pwd=T3kxQ1RvSEd3TGIyY0oxZnJKTnlQdz09

To understand why some innovation-driven portfolio firms benefit more from venture capital (VC) funding than others, I explore the salient phenomenon of founder CEO exit. Integrating institutional logics and psychological contracts theories, I propose a meso-level theoretical framework that identifies and explains how an institutional logic of new venture professionalization shapes suboptimal founder CEO exit strategy in portfolio firms. Founder CEO exits may enhance institutional legitimacy, while also fostering contentious relational dynamics that undermine trust and cooperation between founders and venture capitalists; spill over to affect observers; and contribute to a negative sociopolitical climate within portfolio firms. I derive and test hypotheses about the paradoxical effects of founder CEO exit on portfolio firm performance over time and likelihood of failure, including how the conditions of exit – namely, the timing and nature of the exit event – influence those outcomes. I use growth modeling and logistic regression to analyze a unique panel data set of 182 high-technology portfolio firms, founded 1990-2010. Despite mixed empirical results, I found overall support for my proposition: Rigid implementation of founder CEO exit strategy in portfolio firms may improve some short-term metrics of performance (i.e., valuation), while imperiling other longer-term outcomes (i.e., profitability and odds of survival).

Candidate Name: Jimmeka Lashonda Anderson
Title: Incidents in the life of a cyber girl: Exploring Instagram as a potential counterspace for Black girls' literacy practices
 April 07, 2022  12:00 PM
Location: Zoom

Although research has been done to explore social media as a safe space for Black girls (Womack, 2013), there is limited research that assesses social media as a counter space for Black girls’ literacies. According to The Associated Press-NORC Center for Public Affairs Research (2017), Black teens are the largest users of Instagram and SnapChat. While broader research has looked at Black girls' literacies and digital literacies among this population (Price-Dennis, 2016), there is limited research that has explored the literacy practices of Black girls specifically in the digital space they predominantly use, Instagram. Most importantly, the need to explore the elements of literacy that engage Black girls in non-formal academic spaces in which they utilize excessively may provide context for application in academic curriculum. This research study explores whether Instagram may provide a potential counterspace for Black girls' literacies and the ways in which they practice literacy through the examination of digital posts, online observations, and interviews with two adolescent Black girls.
Keywords: Instagram, Counterspace, Black Girls, Literacy, Social Media

Candidate Name: Charlotte Hancock
 March 21, 2022  11:00 AM
Location: Virtual

This quantitative study examined the awarding of the Seal of Biliteracy (SoBL) in North Carolina public schools. Specifically, the study explored through a multiple logistic regression if the intersectionality of race, language, and class was related to whether a district did or did not award students the SoBL. The dependent variable of total student enrollment was also included. Additionally, within districts found to award the SoBL, this study examined through a multiple linear regression if the variables of race, language, and class related to the rate of graduating seniors who received the SoBL recognition. Total student enrollment was also included as a dependent variable. Results from the multiple logistic regression revealed that total student enrollment, while controlling for language, race, and class was related to whether a district did or did not award the SoBL. Within districts that awarded the SoBL, results from the multiple linear regression revealed that while controlling for race, class, language, and total student enrollment, class was negatively related to the rate of seniors who received the SoBL while language was positively related. Results are discussed through the theoretical framework of critical race theory, and salient recommendations are provided for the future.