On Stable Parameter Estimation and Optimal Control in Epidemiology

A clear understanding of the actual infection rate is imperative for control and prevention of diseases. This knowledge is essential in formulating effective vaccination strategies and assessing the level of herd immunity required to contain the virus. In recent years, advanced regularization techniques have emerged as a powerful tool aimed at stable estimation of infectious disease parameters that are crucial for the design of adequate public health policies. This dissertation presents a theoretical and numerical study of a novel optimization procedure aimed to achieve a stable estimation of incidence reporting rates and time-dependent effective reproduction numbers using real data on new incidence cases, daily new deaths, and vaccination percentages. The iteratively regularized optimization algorithm introduced here is versatile and applicable to a wide range of data fitting problems constrained by various biological models, particularly those that need to account for under-reporting of cases. To support this, general nonlinear observation operators in real Hilbert spaces are used in the proposed convergence analysis. The theoretical findings are demonstrated through numerical simulations using the susceptible unvaccinated (S), susceptible vaccinated (V ), infected unvaccinated (Is), infected vaccinated (Iv), recovered (R), and deceased (D) compartmental model and real data from the Delta variant of the COVID-19 pandemic in different states of the US. In the second part of this dissertation, a biological model with a flexible choice of control strategies for an emerging virus is considered. In the model, the disease transmission is mitigated using both non-medical control (like social distancing and other behavioral changes) and the control by treatment with antiviral medication.Doctor of Philosophy (PhD)Mathematics and Statistic

Meaningful Media Experiences and Vaccination Message Communication: An Experimental Study with Vaccine-Hesitant Individuals

Guided by the eudaimonic media and the health persuasion literature, the current study explores how meaningful emotions elicited from entertainment media exposure decreases anti-vaccination attitudes among vaccine-hesitant individuals. Results of a between-subjects experiment (N = 409) showed that participants who viewed meaningful music videos (vs. neutral videos) and vaccination messages embedded in the user-generated comments reported more empathy, less reactance, and less anti-vaccination attitudes. Multigroup analysis revealed that this association was held for participants who were hesitant about whether they would get fully vaccinated, but not for participants who were determined to not get vaccinated. Theoretical and practical implications were discussed.Accepted manuscript version of an article published by Taylor & Francis in Yachin, M. & Duong, H. (2024). Meaningful media experiences and vaccination message communication: An experimental study with vaccine-hesitant individuals. Journal of Health Communication, 29(4), 274-283. https://doi.org/10.1080/10810730.2024.2339229</p

The Impact of Early Mental Health Education Based on Interventions Among College Students

The Impact of Early Mental Health Education Based on Interventions Among College Students Background: First-year college students have the potential to experience high stress, depression, and anxiety during their transition period from high school. The study examines whether exposure to an online mental health education program is associated with counseling service utilization. Methods: A retrospective cohort design compared counseling center service utilization among first-year students at two southeast public universities. One university requires students to complete an online mental health education program, compared with another public university without this requirement. T-tests were conducted to examine the difference in mean counseling service utilization between the students at the intervention and comparison campuses. Chi-square analyses were carried out to examine counseling service utilization concerning age, race, and gender. Results: The study sample included 1781 (total student records). Descriptive analysis revealed that students at the intervention campus (with the online Mental Health module) utilized counseling services at a higher level (≥3 visits), compared to the comparison campus (without the module). The mean number of sessions was higher at the intervention campus (mean = 3.99) than at the comparison campus (mean = 1.12), with a statistically significant difference (t (1380.18) = 20.71). Chi-square independence tests showed no significant associations between counseling utilization and race, age, and gender. Conclusion: The study's findings reveal that online mental health modules may be associated with increased counseling utilization. This research contributes to the growing body of literature on preventative mental health strategies in higher education and addresses gaps in knowledge about the early interventions and associated utilization of first-year students based on race, age, and gender.Doctor of Public Health (DrPH)Public Healt

Green Light: Investigating Cannabis-Related Public Health and Public Safety Shifts in the Era of Legalization

This dissertation investigates the impact of recreational cannabis legalization (RCL) on law enforcement, public safety, and public health through three interconnected studies. The first paper examines racial and age-related disparities in cannabis law enforcement during the era of legalization. It utilizes city-level data and modern analytical techniques to explore how shifts in policy have influenced arrest patterns across various demographic groups. The second paper explores the effect of state-level cannabis advertising restrictions on cannabis risk perception, initiation, and use among adolescents, young adults, and adults. By using a continuous indicator of marketing restrictiveness, this research assesses how variations in advertising regulations impact cannabis-related behaviors and perceptions across different age groups. The third paper revisits the impact of cannabis laws on cannabis-involved driving, employing updated data from the Fatal Accident Reporting System (FARS) to analyze trends in cannabis-related traffic fatalities. This study focuses on incidents with confirmed blood tests and several person-level covariates to offer a more accurate assessment of the impact of legalization on cannabis-involved crashes. The results of these studies provide a comprehensive analysis of RCL's consequences, revealing significant findings related to enforcement disparities, the effectiveness of marketing restrictions, and the impact on driving safety. These insights aim to inform policymakers on balancing public health, safety, and social equity in the evolving landscape of cannabis regulation.Doctor of Philosophy (PhD)Criminal Justic

Relationships between Body Mass Index, Adiposity Distribution and Treatment Outcomes among Patients with Tuberculosis from the Country of Georgia

The relationship of low BMI and an increase in BMI with TB treatment outcomes is not well characterized. Assessing adiposity distribution in addition to BMI may improve the characterization of the metabolic status of patients with TB. This dissertation aimed to determine the association of body composition with TB treatment outcomes among patients with TB. Study 1 aimed to assess the association of baseline BMI with TB treatment outcomes among adult patients with drug-resistant TB. We also examined whether these associations differed by baseline glycemic status. We used log-binomial models to estimate risk ratios (RR). Compared to individuals with normal BMI, patients with BMI2 were significantly more likely to remain sputum culture positive after two months of treatment (aRR=1.25; 95%CI: 1.06-1.49). The risk of non-conversion by month two was significantly higher among patients with low BMI and hyperglycemia than those with normal BMI and euglycemia (RR=1.54, 95% CI:1.23-1.92). The risk of poor TB treatment outcomes was significantly higher among patients with normal/high BMI and hyperglycemia than those with normal BMI and euglycemia (RR=1.28, 95% CI: 1.03-1.59). Study 2 assessed whether lack of weight gain during the initial months of treatment was associated with all-cause mortality. We used competing-risk Cox proportional hazard models to estimate hazard ratios (HR). Among adults with normal baseline BMI, weight loss compared to weight gain was associated with an increased risk of death during TB treatment (aHR=5.0; 95%CI 1.2, 19.9). Among adults with low baseline BMI, no change in BMI compared to an increase in BMI was associated with an increased rate of all-cause post-TB mortality (aHR=6.1; 95% CI: 1.5, 24.5). Study 3 aimed to determine the association between adiposity distribution (fat mass (FM)/fat-free mass (FFM)) and the prevalence of metabolic disorders among patients with drug-sensitive TB. We used multinomial logistic models to estimate odds ratios (OR). Initial high FM/FFM was significantly associated with hyperglycemia (aOR: 16.2; 95% CI: 1.5, 92.7). This dissertation studies provide valuable information that can be used to prioritize the development of targeted interventions that simultaneously address weight, adipose distribution, and metabolic disease among people with TB.Doctor of Philosophy (PhD)Public Healt

Two Centuries of Defining Moments for Black Women Higher Education Leaders in the United States

Black women have made significant strides in their representation in higher education leadership in the United States over the past two centuries. They have faced barriers, yet they have also made substantial contributions to the field. Historically, Black women remain at the forefront of the struggle for equal access to education, with many earning degrees, becoming educators, and founding higher education institutions. However, their leadership roles have often been marginalized and overlooked. Despite this, Black women have persevered and made advancements in higher education administration, but they continue to face obstacles in their career paths and leadership progression. The experiences of Black women higher education leaders, including the challenges they encounter and the strategies they employ to overcome them, can provide valuable insights for improving the retention and advancement of Black women leaders. Achieving gender equality in leadership positions in higher education is a matter of fairness, and it is essential to advancing the evolving higher education landscape.</p

Individual and Community Characteristics Associated with Recent Transmission of Tuberculosis in Rural Areas of the United States, 2011–2021

Problem: In the United States, social inequities are concentrated in rural areas, potentially increasing the risk for recent transmission (RT) of tuberculosis (TB), a precursor of TB outbreaks. Most TB cases occur among non-U.S.–born patients; however, little is known about TB in rural areas. This dissertation examined characteristics associated with RT in rural areas. Methods: TB cases with genotyping results reported to the National Tuberculosis Surveillance System during 2011–2021 were included if they occurred in areas classified as non-metropolitan (rural) by the National Center for Health Statistics. Community characteristics included county-level poverty (American Community Survey) and number of primary care physicians (PCP) per 100,000 (Health Resources and Services Administration). Hierarchical generalized linear models were constructed to estimate the relative association of individual and county characteristics with RT. Results: During 2011–2021, 7,607 rural U.S. residents were diagnosed with TB. Patients lived in counties with a mean of 20% (SD=7.0) of the population below poverty and 49 (SD=27) PCPs per 100,000. Most patients were male (66.0%), U.S.-born (63.8%), and identified as a racial or ethnic minority (74.1%). TB was attributed to RT for 847 (15.0%) of 5,633 cases with an RT designation. Most patients with TB attributed to RT lived in the U.S. Census South Region (65.6%), followed by the West (27.2%), Midwest (6.4%), and Northeast (0.8%); nearly all were U.S.-born (90.3%). County and patient characteristics, except age, differed significantly by region. In hierarchical models, U.S. birth (odds ratio=5.05, 95% CI: 3.62–7.04), racial/ethnic minority identification (1.54, [1.13–2.11]), incarceration (0.46, [0.26–0.80]), age (0.97, [0.97–0.98]), and county PCP ratio (0.99, [0.98–1.00], p=.02) were associated with RT, whereas homelessness, substance misuse, comorbidities, and county-level poverty were not. Conclusion: Unlike national epidemiology, most patients with TB in rural areas, and nearly all whose TB was attributed to RT, were U.S.-born. Healthcare providers in rural areas should consider TB as a potential diagnosis among symptomatic U.S.-born patients of racial or ethnic minority groups. More attention is needed to highlight the unique characteristics of patients with TB due to RT in rural areas.Doctor of Philosophy (PhD)Nursin

The Role of Occupational Therapy with Homeless or Ill-Housed Persons: Perception and Understanding of Occupational Therapy Among Parents and Staff at the Atlanta Children's Day Shelter

Background: People experiencing homelessness oftentimes face barriers that those who are not homeless rarely do. These barriers can range from having limited access to healthy foods and proper healthcare but can also entail experiencing mental illness and substance abuse disorders more frequently than people who have stable housing. There are many different research studies and articles concerning the cause of homelessness, the best interventions for those facing homelessness and so much more. However, there is little research on what occupational therapy, a healthcare profession that focuses on rehabilitating, establishing or maintaining the skills needed to participate in activities of daily living, can do for the lives of children experiencing homelessness. Objective: The purpose of this study was to explore the perceptions, understandings, and role that occupational therapy plays with homeless or ill-housed children in the Atlanta area by creating and implementing four different occupational therapy educational modules and presenting them to parents and teachers at the Atlanta Children’s Day Shelter. ACOTE Areas: The ACOTE areas most closely related to this capstone experience are centered around research, advocacy and most importantly, education. Educating the teachers and parents at the Atlanta Children’s Day Shelter about what occupational therapy is, how it can benefit their students/children and how to receive occupational therapy services was consistently at the forefront of this capstone experience. Additionally, providing parents/staff with up-to-date research and encouraging them to advocate for themselves and their students/children played a major role in the capstone student’s ability to make a lasting impact. Methods: The capstone student developed and presented four educational modules to the teachers and parents who were actively employed or had children actively enrolled at the day shelter. The topics of the educational modules were centered around the needs of the day shelter and how occupational therapy can transform to fit those needs. Each educational module was created in both a graphic handout version and whiteboard animation video format. To measure the effectiveness of the information provided, parents that participated were urged to complete anonymous surveys at the end of each module. The data from each survey was then analyzed into statistical deliverables. There were four additional smaller projects for implementing the capstone experience throughout outlined in further detail in “Project Design” section of paper. Results: The results from the anonymous surveys displayed clear trends pointing towards the parents having an inherent desire towards learning more occupational therapy and how it can be introduced into their children’s lives. Results for each individual modules and combined results are in the “Results” section of paper below. Conclusions and Relevance: Results from anonymous surveys, observed attitudes, willingness to learn, and questions asked during Parent Pods displays that parents experiencing homeless are truly interested in learning and implementing occupational therapy interventions in their children’s lives. Background research displays the effectiveness of occupational therapy intervention within the homeless adult population and the results from this capstone experience displays the need for more research and intervention efforts within the homeless or ill-housed pediatric population.Doctor of Occupational Therapy (OTD)Occupational Therap

Factors affecting Preparedness in Cybersecurity Risk Management among Small and Medium-Sized Enterprise (SME) Leaders

Small and medium-size enterprise (SME) leaders are ignoring the significance of cybersecurity risk management. The statistics for the number of SME organizations becoming victims of cyber-attacks increased significantly in 2025 and beyond. Although most SME leaders perceive themselves as non-targets, cybersecurity remains a key area of focus that all firms, regardless of their size, must confront. The area of concern or problem is that many SME organizations are operating without cybersecurity risk management and are at risk of a cyber-attack. The study's findings indicate that 42.5% of the 259 SME leader survey participants had not made an investment in cybersecurity. To investigate behavioral decisions in SME leaders, this study used the Behavioral Decision Theory (BDT) to understand the cognitive biases and heuristics that influenced the decision making of SME leaders. This was a quantitative study of 259 SME leaders residing in the United States that examined leader risk awareness, leader risk tolerance, and leader decision making (Melbourne Decision Making Questionnaire) to identify factors affecting preparedness in cybersecurity risk management. From a theoretical perspective, the findings expanded the understanding of decision leadership-making in cybersecurity preparedness by demonstrating that risk awareness plays a vital role in predicting preparedness. From a practical standpoint, the results can be used to guide on the activities through which leadership of SMEs can improve their preparedness in terms of cybersecurity.DB

Role of Arc Turnover in Tauopathies

Tauopathies are neurodegenerative disorders characterized by the deposition of aggregates of the microtubule-associated protein tau. Alzheimer’s disease (AD) is the most common type of tauopathy and dementia, with amyloid-beta pathology as an additional hallmark feature of the disease. Tau is localized at postsynaptic sites and can disrupt synaptic plasticity when knocked out or overexpressed. The activity-regulated cytoskeleton-associated protein (Arc), is an immediate early gene that plays a key role in synaptic plasticity, learning and memory. Arc has been implicated in AD pathogenesis, where it was found to regulate activity-dependent release of amyloid-beta (Ab). Given that high levels of Arc have been detected in an Ab mouse model and post-mortum cortical tissue from AD patients, we hypothesized that disruption of Arc turnover can participate in AD pathogenesis. We investigated the role of Arc turnover mediated by ubiquitination at lysines 268/269 in a middle-aged ArcKR mouse model where these sites are mutated to Arginine. In this model, we did not find abnormal accumulation of tau, Ab or b-amyloid plaques and no disruption in spatial learning. However, we did identify a relationship between tau overexpression and Arc stability, where overexpression of the 0N4R isoform of tau in primary hippocampal neurons led to Arc instability exclusively in neuronal dendrites. Tau-dependent reduction of Arc required proteasome activity yet was independent of Arc ubiquitination. Surprisingly, tau-induced Arc removal required the endophilin-binding domain of Arc, which is a domain that is essential for promoting the endocytosis of α‐amino‐3‐hydroxy‐5‐methyl‐4‐isoxazolepropionic acid (AMPA) receptors. This was coupled to increases in the expression of dendritic and somatic surface GluA1-containing AMPA receptors. Interestingly, these effects on Arc stability and GluA1 localization were not observed in the commonly studied tau mutant, P301L. We also show that endogenous tau has a physiological role in regulating Arc, where Arc levels are upregulated in the hippocampus of tau knockout (Tau KO) mice and in dendrites of primary hippocampal neurons. Our findings implicate specific variants of tau in regulating Arc stability and AMPA receptor targeting, which may in part explain deficits in synaptic plasticity that are observed in select types of tauopathies.Doctor of Philosophy (PhD)Neuroscience Institut