Doctoral Dissertations (Winter 2014 to Present)

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New submissions to the University of Delaware Doctoral Dissertations collection are added as they are released by the Office of Graduate & Professional Education. The Office of Graduate & Professional Education deposits all dissertations from a given semester after the official graduation date.

Doctoral dissertations from 1948 to present are also available online through Dissertations & Theses @ University of Delaware. Check DELCAT Discovery to locate print or microform copies of dissertations that are not available online.


More information is available at Dissertations & Theses.

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Recent Submissions

Now showing 1 - 5 of 2007
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    What's the problem (and does it matter)?: Exploring the relationship between educators' problem-framing and external research use
    (University of Delaware, 2022) Tilley, Katherine
    This paper documents an investigation into the nature of the relationship between problem-framing and reported engagement with external research evidence in school-based decision-making. This study serves as an important first attempt to explore and describe this potential relationship and its implications for the use of research in schools. Situated within the context of a larger knowledge utilization research center, the current study uses qualitative and quantitative data from 1,343 K-12 educators collected during the large-scale administration of the Survey of Evidence in Education for Schools (SEE-S). Specifically, the study is guided by the following research questions: 1) What are the problems schools addressed in recent decisions and how are those problems understood by individuals working within those schools? 2) What is the relationship between problem-frame and the likelihood of the respondent indicating that research was used in the decision-making process? ☐ The study employed an a priori coding framework to distinguish types of problem-frames, followed by subsequent binary logistic regression analyses to assess the potential relationship between problem-frame type and the likelihood of a respondent indicating that external research was used in a decision-making process. Results suggest that school-based practitioners are facing a wide array of problems and that they understand these problems in diverse ways. Additionally, results of regression analyses provide evidence for the relationship between problem-frame type and reported external research use in decision-making. Specifically, seven problem-frame types were found to have a statistically significant relationship with reported external research use. These findings have implications for how the education research and policy communities understand school-based decision-making and problem-solving and the role that research may play.
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    Diversifying Delaware's teacher pipeline: a descriptive study of the University of Delaware College of Education and human development's Teachers of Tomorrow Program
    (University of Delaware, 2022) Taylor, Deandra S.
    This Education Leadership Portfolio (ELP) focuses on addressing the increasing need for more racial diversity in the Delaware teacher workforce. It is a multi-dimensional effort to meet the increasing need for and supply of teachers of color in the state. Therefore, the scope of this ELP centers around the University of Delaware (UD) College of Education and Human Development’s (CEHD) Teachers of Tomorrow (ToT) Program. This program was created as a diversity initiative tasked with doubling the number of underrepresented students from Delaware enrolled in a teacher education program at the university. ☐ Terms such as “students of color” and “minority” are used interchangeably to refer to students who self-identify as African American, Hispanic/Latino, Asian, Native American, and/or of more than one race. Likewise, the term “teachers of color” is used to refer to teachers from the same previously stated backgrounds. The term “underrepresented” is used to refer to students from a racial/ethnic minority group, who are low-income, or are males interested in pursuing a degree in early childhood or elementary teacher education. ☐ The improvement goals for this ELP were three-fold. The first goal was to evaluate the ToT Program to determine if it could serve as a promising resource to help boost recruitment efforts geared toward gaining more students of color into the field of teacher education. To address the first improvement goal, existing program data were used to evaluate the program’s potential as a viable resource for recruiting future teachers of color. ☐ The second goal was to develop a deeper understanding about what influences students in general, and students of color specifically, regarding their decision to pursue a career in teaching. To accomplish the second improvement goal, a mixed methods study was conducted on students’ perceptions of the ToT Program and general factors that influenced their post-secondary decisions. ☐ The third goal was to raise awareness regarding efforts to racially diversify the Delaware teacher pipeline. To address this goal, I took several opportunities to share my research with broader audiences, to help increase the visibility of the ToT Program and recruitment efforts to diversify the Delaware teacher pipeline. ☐ Findings from the ELP shed a positive light on the perceived influence the ToT program had on its participants and further insight is given regarding what is important to students of color. Recommendations are provided to the program staff to suggest ways to further enhance the program.
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    Patterns and processes governing greenhouse gas emissions from tidal salt marsh soils
    (University of Delaware, 2022) Capooci, Margaret
    Coastal vegetated ecosystems, such as tidal salt marshes, mangrove forests, and seagrass beds, store large amounts of carbon and thereby have been referred to as “blue carbon” ecosystems. These ecosystems also release carbon in the form of carbon dioxide (CO2) and methane (CH4), as well as other climate-active trace gases such as nitrous oxide (N2O), carbon disulfide (CS2), and dimethylsulfide (DMS). There is high uncertainity about the production and emissions of these gases from salt marsh soils, as well as their spatiotemporal variability. Knowledge about soil trace gas fluxes is important for calculating budgets, calibrating models, and assessing the viability of marshes as natural climate solutions. This dissertation focuses on better understanding the patterns and processes that govern greenhouse (GHG; CO2, CH4, N2O) and sulfur-based gas (CS2, DMS) fluxes from soils in a Mid-Atlantic temperate tidal salt marsh. Fluxes were measured using a variety of chamber techniques, coupled with biophysical and biogeochemical measurements. ☐ The first study presented in this dissertation investigates the effect of storm-surge salinity changes on GHG fluxes from tidal salt marsh soils, with the goal of understanding how fluxes respond to and recover from salinity changes. A flow-through mesocosm experiment was coupled with automated GHG flux and pore water chemistry measurements. Decreases in salinity contributed to an increase in GHG fluxes. Throughout the experiment, the role of different biogeochemical processes in producing GHG fluxes changed over time. This underscores the complex nature of the production and emission of GHG, particularly during extreme events. Once salinity returned to the initial conditions, CH4 and N2O fluxes returned to baseline within 15 days, illustrating that tidal salt marshes are resilient ecosystems. ☐ The second study sought to better quantify CO2 fluxes, as well as identify its main biophysical drivers using long-term, continuous data collected in the field. Hourly averages of CO2 flux were collected at two sites for ~20 months, as well as manual CO2 flux data to assess spatial variability. This study comprises of the first long-term datasets of soil CO2 flux measurements from a salt marsh. Although seasonal patterns of CO2 fluxes were found, there were no consistent diel patterns. The main biophysical driver of CO2 flux was air temperature, but other drivers such as water level, salinity, PAR, and NDVI played roles. Manual measurements collected every two weeks underestimated the annual flux, highlighting the need for high-frequency data to calculate annual budgets more accurately. ☐ The third study built upon the questions about biophysical drivers and measurement techniques posed in the second chapter to include CH4, N2O, CS2, and DMS. Continuous, automated chambers were deployed for ~72 hours throughout the year to obtain high-temporal frequency data to assess how gas fluxes changed throughout the day and over tidal cycles. No consistent diel patterns were found, but rather CH4, N2O, CS2, and DMS fluxes were highly variable with frequent pulse emissions. Likewise, when continuous measurements were compared to discrete (during daytime, at low tide) measurements for these four gases, discrepancies arose due to high temporal variability. However, both continuous and discrete measurements of CO2 provided similar information regarding the mean and distribution of CO2 fluxes, providing support for the use of discrete measurements of CO2 for budgets. ☐ The fourth study sought to better understand CH4 production and fate in tidal salt marsh soils. The continuous, automated measurements of CH4 and CO2 performed in the third study were coupled with measurements of soil CH4 and CO2 gas concentrations, stable and radioisotopes, pore water and organic carbon chemistry, and microbial community composition. CH4 was found to be produced by two pathways: hydrogenotrophic and methylotrophic methanogenesis, the latter of which can produce CH4 in the presence of sulfate reduction. Once produced, data showed that CH4 can take a variety of pathways: diffusion into the atmosphere, CH4 oxidation, and lateral transport to the tidal creek. The findings showed that CH4 production and fate is biogeochemically heterogeneous and that each process involved varied in importance over the growing season. ☐ Overall, this dissertation provided key insights into the spatiotemporal variability of greenhouse and sulfur-based fluxes from tidal salt marsh soils, as well as the processes that produce these gases. The findings from these studies will provide better insights for scientists and policymakers on the role salt marshes have in the carbon cycle as well as provide better GHG estimates for evaluating whether salt marshes are a net carbon sink.
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    Efficient and scalable cloudlet placement approaches for edge computing in next-generation networks
    (University of Delaware, 2022) Bhatta, Dixit
    Emerging applications with low-latency requirements such as real-time analytics, immersive media applications, and intelligent virtual assistants have rendered Edge Computing as a critical computing infrastructure. Since large data centers cannot be placed everywhere, placing cloudlets nearby the users provides an effective solution to these requirements. Existing studies have explored the cloudlet placement problem in a homogeneous scenario with different goals such as latency minimization, load balancing, energy efficiency, and placement cost minimization. However, placing cloudlets in a highly heterogeneous deployment scenario considering the next-generation networks and IoT applications is still an open challenge. ☐ The goal of this dissertation is to specifically tackle strategic placement of cloudlets to reduce costs associated with providing edge services (deployment cost, energy consumption) as well as improving metrics important to the users such as coverage, service stability, and access latency. These problems are significantly challenging because the cloudlets have limited capacities whereas users have dynamic demands. Moreover, both users and cloudlets can be heterogeneous. As we move into next-generation networks and IoT, the placements need to be done in even denser and highly heterogeneous scenarios. Another challenging aspect is the continuous user mobility. These several placement challenges in edge computing systems are hence addressed by mathematically modeling diverse placement scenarios based on real-life constraints. However, the complexities of these problems make the mathematical models inherently NP-hard, even with the simplifying assumptions. As a result, the core of the research lies at solving these problems by designing efficient and scalable solution approaches.
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    "Chains that have kept me bound have been broken free": exploring narratives of self-forgiveness within prison walls
    (University of Delaware, 2022) Demarest, Megan Terry
    An abundance of research exists detailing the benefits of engaging in interpersonal forgiveness across various domains of life (e.g., personal, health, relationships), yet less is known about the implications of intrapersonal forgiveness, specifically in the aftermath of a crime. In fact, self-forgiveness research within criminology is in its infancy. Recent findings problematize this omission by offering promising suggestive evidence of the potential value of forgiving the self, including increased wellbeing, attribution of responsibility, and a commitment to future prosocial behavior (Jenkins, 2018). However, theoretical ambiguity persists regarding potential linkages between self-forgiveness, identity, and human agency following the commission of criminal acts (Suzuki & Jenkins, 2020). As a result, the current study significantly contributes to the conversation surrounding self-forgiveness among those formally involved in the criminal justice system through its investigation of the following questions: how do individuals articulate the process of self-forgiveness?; how do individuals articulate the factors that influence self-forgiveness?; how, if at all, does identity (e.g., race, gender, class) influence the self-forgiveness process?; and how, if at all, do theoretical identity frameworks inform our understanding of self-forgiveness? Written narratives are analyzed to garner a deeper understanding of self-forgiveness processes experienced by criminal justice-involved persons. Findings provide deeper insight into the healing aspects of self-forgiveness, while also illuminating how self-forgiveness can inform correctional practices and policies.