Dissertation Defense Announcements

Candidate Name: Pramesh Subedi
Title: Semiparametric Additive Hazards Models with Missing Covariates
 April 14, 2021  2:15 PM
Location: Online via Zoom
Abstract:

In this paper, we have applied case cohort study design to semiparametric additive hazard models to study the effect of covariates on failure times. We have considered the phase one covariates to have both time varying and constant effect on failure time while phase two covariates have constant effect. We have applied Augmented Inverse Probability Weighted (AIPW) method to estimate the model
parameters and compared the result with widely adopted Inverse Probability Weighted (IPW) method. Our simulation study shows that AIPW estimation is more consistent than IPW estimation method. The method is applied to analyze the RV144 vaccine trial data to assess whether immune response and behavioral risk level has effect on HIV-1 infection.



Candidate Name: Melissa Miller Sykes
Title: TEACHING THE TEACHERS: A CASE STUDY OF INSTRUCTIONAL LEADER PROFESSIONAL DEVELOPMENT
 April 12, 2021  11:00 AM
Location: Zoom Meeting
Abstract:

The purpose of this qualitative study was to explore professional development from the perspective of instructional leaders to identify if the assumptions of Knowles’s (1990) Adult Learning Theory were present in the planning and implementation of continuing education. A qualitative case study research design was utilized, and the research setting was dependent on the participants and the locations in which they were contracted to conduct continuing education sessions with teachers. The instructional leaders were committed to plan and present professional development at three different suburban schools surrounding a city in the Southeastern United States. The participants in the study were instructional leaders and educational consultants with at least 10 years of experience who work across school districts with multiple elementary, middle, and high school sites in suburban and urban districts. Data sources included two rounds of interviews, observations of planned and implemented professional development, and document analysis of staff development materials. The data was analyzed using thematic analysis that included within-case and cross-case investigation.



Candidate Name: Ping Mao
Title: The development of Chinese overseas joint venture universities and their role in Chinese higher education
 April 16, 2021  9:30 AM
Location: Zoom
Abstract:

This dissertation investigates a newly emerging phenomenon in Chinese higher education in which a Chinese university partners with an overseas university to open a new university campus in China which began in 2004. This form of university was established in the context of economic growth and education reform in Chinese society. It has brought a change to the rebuilding of nonpublic higher education in China since the late 1980s. It also reinforces the emphasis on internationalization and diversification of higher education set by Chinese government for the 21st century. However, as a joint venture in higher education, this form of education is still unknown to many education scholars with respect to its formation mechanisms and motivations. Moreover, given the changing landscape of Chinese higher education, the current status and future prospects of this type of university are worthy of study considering its benefits as well as challenges for Chinese and the global higher education development. What is more, the social, economic, and policy implications of these universities are even more enormous than its education perspective.
This dissertation is an exploratory case study involving intensive interviews with seven administrators and nine students from four institutions in this study along with content analysis of mission statements and school documents involving all nine institutions in this group. Findings suggest that the emergence of joint venture universities is consistent with the growing trend of globalization and internationalization in worldwide higher education development. Motivations and goals of institutions in pursuing this cooperation may vary among countries. China’s governmental involvement in this kind of education signifies a new trend in higher education collaboration that incorporates governmental interest in political, economic, and global pursuits rather than focusing on the education per se. Thus, this type of joint venture universities is neither public nor private. An unexpected finding is that the emergence of this form of education did not improve education inequality existing in Chinese higher education due to geographical location but reinforce the reproduction of inequality. Also, the small number of special joint venture universities in China seem to aim more for advancing China’s international goals to engage on the global stage, foster China’s active globalization efforts, and prepare Chinese students to be academically and socially ready for globalization. These findings thus have substantial implications for policymakers in relevant areas and help them in policymaking decisions.



Candidate Name: Kumar Arumugam
Title: Implementation and Evaluation of Optical and Stylus Based Profiling Techniques for Surface Metrology
 April 09, 2021  12:30 PM
Location: MEES conference room, Duke 324
Abstract:

A unifying theme of this thesis is the implementation and characterization of point probes for surface metrology. The implementations include two optical non-contact profiling methods; fiber-based Fabry-Perot interferometry and Confocal microscopy.

Even though Fiber-based Fabry-Perot interferometers are suitable for measuring surface texture in confined space, literature describing its implementation and limitations of this technique are scarce. To explore these knowledge gaps an experimental facility has been built and the feasibility for surface height measurements is validated by measuring two sinusoidal reference surfaces with heights of 1 μm and 1.5 μm and wavelengths of 100 μm and 50 μm respectively.

A second part of this thesis is to implement a flexure-based vertical scanning of an objective lens used for Confocal microscopy to increase the bandwidth of height detection and, therefore, surface scanning speeds. A sinusoidal reference sample is designed and manufactured, which is later measured using a confocal microscope prototype built using a 60X objective lens. A flexure to house the lens stack to provide a surface height scanning range of 10 μm is also designed and fabricated.

A third part of this thesis involves characterizing a stylus-based contact profiler for measuring areal form of freeform optics. Typically, for non-contact optical probes, the probe axis must be orthogonal to the curvature of the part being measured. This is not required for a stylus profiler. Reference objects such as optical flats, prisms, and spheres are measured using the stylus profiler and these measurements are compared with results from a Fizeau interferometer. From these measurements, vertical error of the X scanning carriage, side loading on the stylus probe due to the surface slope of the part being measured are estimated. A geometrical model of the profiler has been developed and used in a Monte Carlo simulation that predicts an uncertainty in the areal form measurements of less than 100 nm PV for a 100 mm measurement aperture.



Candidate Name: Qiuyu Chen
Title: REPRESENTATION LEARNING OF IMAGE RECOGNITION: DIVERSITY, ASPECT RATIO, INVARIANCE, AND COMPOSITION
 April 12, 2021  9:00 AM
Location: Zoom
Abstract:

Deep neural networks (DNN) are proved to be effective and improve the performance dramatically in various kinds of computer vision tasks. The end-to-end learning manner in training DNN consistently shows the powerful modeling ability and consequently mitigates the dedicated efforts for expert feature engineering. On the other hand, it raises the issue that how to improve the black-box network with better representation (feature) learning especially when the learned representations and classifiers are tied together in the manner of supervised learning. In this work, representation learning is studied in four perspectives of different fields, i.e. diversity in ensemble learning, aspect ratio in image aesthetics assessment, invariance in identification task, and composition in color attribute recognition.

In light of analyzing the bottleneck of black-box network and designing better representation learning for target tasks, we introduce that: (a) Ensemble learning relies on the diversity of the complementary neural networks, in both feature representations and classifier representations. A diverse representation learning method, namely learning-difficulty-aware embedding, is proposed to adaptively reconcile learning attentions for different categories by training a series of networks with diversified representations sequentially; (b) Widely-adopted data augmentation method in image recognition deteriorates aspect ratios, which is an important factor in image aesthetics assessment. An aspect ratio representation learning method, namely adaptive fractional dilated convolution, is proposed to explicitly preserve the learning representation related to aspect ratios by adjusting the receptive fields adaptively and natively; (c) Identification tasks, e.g. person re-identification, aim at learning representations that are robust to interfering variances, e.g. lighting variances, view variances, pose variances. An invariance representation learning method, namely anchor loss, is proposed to train a robust feature extractor, which distills the identity-related representations while disentangling and removing interfering variances by global supervision under local mini-batch training; (d) Color recognition is entangled with compositional representation in both visual perception and language attentions. A compositional learning module with attention to key colors is proposed to learn better color representations. Besides, another compositional learning method, namely classifier as descriptor, is proposed for long-tail color recognition by incorporating the rich knowledge in classifier representations to remove the bias from bias-trained
model.

Through extensive experiments and thorough analysis, we demonstrate some novel insights about the impacts of four factors, i.e. diversity, receptive field, invariance, and composition. Several methods are proposed to learn better representations for those factors, achieving state-of-the-art results in different tasks.



Candidate Name: Xi Mo
Title: Essays in Empirical Asset Pricing
 April 06, 2021  11:00 AM
Location: Zoom


Candidate Name: Felicia Dangerfield-Persky
Title: FACTORS AFFECTING GRADES: AN EXAMINATION OF NORTH CAROLINA SCHOOL PERFORMANCE GRADES
 April 14, 2021  11:00 AM
Location: Virtual via Zoom
Abstract:

This quantitative study explores the potential school-level and school district-level factors associated with North Carolina school performance grades in K-5 elementary schools. The desire was to examine if any of the school- or school district-level factors were associated with the outcome variable of North Carolina school performance grades. This study used the data from the North Carolina school report cards and Civil Rights Data Collection from the 2015 – 2016 school year. The sample had 1096 schools and 92 school districts. A hierarchical linear model was created with the overall school performance grade as the outcome variable and the sixteen school level predictors and thirteen school district predictors. Results indicated that twelve out of sixteen school-level variables were statistically significant. One out of thirteen school district-level variables were statistically significant and two additional variables approached significance. Recommendations for improving student achievement were provided for United States policymakers, university education programs, North Carolina policymakers, local governments, school districts, and schools. These recommendations are presented as opportunities to ensure equitable educational practices and outcomes for all students.



Candidate Name: Edward Lee
Title: Is the Usage of Wearable Devices Worth it? A Study of Perceived Risks and Fashion on Intention of Adopting Wearable Technology
 April 06, 2021  3:00 PM
Location: Zoom
Abstract:

Wearable technology became popular not only in the consumer market, but also in the field of academic research. Studies related to smart wearables have increased dramatically during recent years. However, personal safety perspectives of wearable devices have not been adequately addressed in the literature so far. There have been debates regarding the potential health risk of using wireless technology and batteries from wearable devices. Regardless of the actual health risks from wearable devices, these controversial debates could affect and form users’ perceptions toward purchasing and using the technology. The uniqueness of wearable devices is that they are not only considered as technical devices, but also considered as fashion items. By adding perceived risk and fashnology (combination of fashion and technology) constructs to the Unified Theory of Acceptance and Use of Technology 2 (UTAUT2), this study examines how perceived risks and fashion-related perceptions influence a consumer’s intention to purchase and use wireless earbuds. Based on survey data from a sample group of 205 respondents, Perceived Health Risk, Perceived Fashionability, and wearable comfort have a significant impact on a consumer’s intention to purchase wireless earbuds. These results fill in the gap of wearable technology literature and provide a reason why Perceived Health Risk should be studied more for future research. In addition, practitioners should make sure they produce wearable devices that are safe, fashionable, and comfortable to wear.



Candidate Name: MD Akram Hossain
Title: APE2 IS A CRITICAL REGULATOR OF THE DNA DAMAGE RESPONSE TO MAINTAIN GENOME INTEGRITY IN MAMMALIAN CELLS
 April 09, 2021  3:00 PM
Location: Virtual Meeting via Zoom
Abstract:

The maintenance of genome integrity and fidelity is essential for the proper function and survival of all organisms. Recent studies have revealed that APE2 is required for the activation of an ATR-Chk1 DNA damage response (DDR) pathway in response to oxidative stress and a defined DNA single-strand break (SSB) in Xenopus laevis egg extracts. However, it remains unclear whether APE2 is a general regulator of DDR pathway and what the biological significance of APE2 is in mammalian cells. Here, I provide evidence using mammalian cultured cell lines including human pancreatic cancer cells that APE2 is important for ATR DDR pathway activation in response to different stressful conditions including oxidative stress, DNA replication stress, and DNA double-strand breaks. Fluorescence microscopy analysis shows that APE2-knock-down (KD) leads to enhanced γH2AX foci and increased micronuclei formation. In addition, a small molecule compound is identified as APE2 inhibitor that specifically compromises the binding of APE2 to ssDNA, its 3′-5′ exonuclease activity, and the defined SSB-induced ATR Chk1 DDR pathway in Xenopus egg extracts. Notably, cell viability assays demonstrate that APE2-KD or APE2 inhibitor sensitizes pancreatic cancer cells to chemotherapy drugs. Overall, APE2 is proposed as a general regulator for DDR pathway in genome integrity maintenance in mammalian cells.



Candidate Name: Leslie W. Schmidt
Title: “Seeing it in action is more beneficial than learning about it in school”: A multi-case of clinical experiences and culturally responsive literacy instruction
 April 14, 2021  12:00 PM
Location: Zoom
Abstract:

This multiple case study explored the characteristics of clinical experiences that support preservice teachers' understandings of culturally responsive literacy in elementary classrooms. In particular, this study focused on capturing the voices and perspectives of three preservice teachers through semi-structured interviews, observations, and the collection of artifacts such as literacy lesson plans, journal entries, and photographs. Findings suggest that preservice teachers generally understand culturally responsive teaching as: (a) using a variety of diverse texts; (b) building a learning community that honors students’ cultures, (c) maintaining high expectations for all students; and (d) teachers knowing their students in order to connect the course content to their lives, cultures, and interests based on their coursework and experiences in the clinical setting. Data also showed that clinical educators are the most influential characteristic of preservice teachers’ understandings of culturally responsive literacy and being in the classroom setting is more influential than only learning about culturally responsive teaching through university coursework. Findings also indicate that preservice teachers are developing superficial understandings of culturally responsive teaching, suggesting implications for teacher education and preparation.