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.

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Teachers’ Orientations Toward and Interactions with Students’ Writing in High School Mathematics
Smith, Ethan Palmer
The purpose of this study is to investigate different aspects of teachers’ orientations toward students’ writing in high school mathematics. I used an embedded case study design (Yin, 2018) across the cases of three teachers whose instruction had previously been found to be dialogically focused – i.e., made use of high-level tasks, presented opportunities to share multiple representations or strategies, and included a focus on student discourse (Munter et al., 2015). I first interviewed each teacher to capture their described orientations toward writing in regard to math teaching and learning. I then conducted four observations of each teacher’s instruction to detail the types of interactions that they had with students’ writing. Finally, I conducted post-observations with each teacher to gain insight into their own interpretations of their observed lessons. My findings indicate that these teachers recognized writing as a tool to support student communication and reasoning, but that they situated writing as an embedded practice informed by their views on discourse and student self-efficacy. I also found that these participants enacted a range of interactions across different types of writing tasks, indicating that – while certain types of tasks may support more student-directed interactions – the teacher still plays a significant role as a facilitator of classroom discourse. This dissertation contributes to the field by suggesting approaches for better capturing factors that influence math teachers’ orientations toward writing, and by indicating how noticing activities that include multiple mediums of evidence of student thinking might help such teachers to adopt a stance of inquiry (van Es & Sherin, 2021) toward students’ writing.
Exploring the effects of the statewide implementation of an automated writing evaluation system among K-12 students
Huang, Yue
Automated writing evaluation (AWE) is a cutting-edge technology-based intervention designed to help teachers meet their challenges in writing classrooms and improve students’ writing proficiency. The fast development of AWE systems, along with the encouragement of technology use in the U.S. K–12 education system by the Common Core State Standards (CCSS), has led to increased adoption of AWE systems by schools and districts. However, implementation has largely outpaced research (Shermis et al., 2016; Xi, 2010), especially with regard to rigorous evaluations of AWE efficacy. This dissertation study aims to investigate the naturalistic statewide implementation of an AWE system known as Utah Compose (UC), and to rigorously explore the short-term and long-term effects of UC usage on students’ state test English Language Arts (ELA) performance using quasi-experimental designs. Specifically, this study employed descriptive analyses and hierarchical linear modeling (HLM) to understand the users and the usage of UC in Grades 3–11 across five school years from 2015 to 2019. To compare the effects of more-UC-usage on students’ ELA performance with the less-UC-usage and no-UC-usage in its single year of implementation in school year 2015, this study used propensity score weighting method. In addition, the inverse probability of treatment weighting (IPTW) method was adopted to examine the cumulative years of effects of UC implementation over four school years (2015–2018) on students’ ELA performance. Findings showed that UC had been widely used in the state for all years, but usage had varied across grades. Most UC users only utilized its main feature targeting writing prompts practices and did not use the other embedded features. The detailed usage of UC was determined by factors not only at the student level but also at the teacher and school levels. Regarding UC’s single year of effect, the results showed that students with greater UC usage performed better in ELA compared to their expected ELA scores if they had not been exposed to UC at all (effect size = 0.17) or if they had used UC less frequently (effect size = 0.11). Furthermore, English language learners, students in special education programs, and low-income students with greater UC usage benefitted more in ELA performance, but the improvements were not sufficient to close the performance gap between them and their peers. Additionally, there was a cumulative benefit to students who used UC repeatedly, but those cumulative effects decreased each year and peaked after three years of implementation. This study is the largest evaluation of AWE effects to date in terms of both its substantial sample size and scope. The findings regarding AWE’s usage and its causal effects on students’ ELA performance, which is a distal and important outcome at the state level, collectively have significant implications for policy and practice regarding large-scale AWE implementation.
OPTIMAL ADAPTIVE TREADMILL CONTROL TO MAXIMIZE PROPULSION DURING GAIT
Pariser, Kayla
The ability to predict who will benefit from which treatment and how to customize treatments to individuals is a grand challenge in the biomechanics community. In particular, due to the heterogeneity of the post-stroke population, selection of optimal rehabilitation protocols that maximize recovery of walking function often involves extensive trial and error, resulting in patient fatigue and increased healthcare costs. Treadmill-based gait training is commonly prescribed for post-stroke rehabilitation but yields mixed responses possibly due to the use of standardized approaches instead of customized protocols. The overall purpose of this dissertation was to understand and predict user responses to various treadmill training protocols to determine who will benefit from which protocol. This goal was accomplished through a combination of musculoskeletal modeling and simulation techniques and experimental gait analysis. In the first Aim we developed and evaluated the first predictive framework to estimate several common gait adaptations on a fixed-speed treadmill at a range of belt speeds. This proved the feasibility of combining musculoskeletal models and direct collocation optimal control methods to simulate gait on a treadmill. Although fixed-speed treadmill gait training can be a useful rehabilitation tool, adaptive treadmill control may provide a more similar training environment to community ambulation. In Aim 2 we sought to create a customizable adaptive treadmill controller to promote increased user propulsion, a common goal of post-stroke gait rehabilitation. We recruited and tested a cohort of 22 young healthy adults and the results show that we can customize an adaptive treadmill to target increased propulsion. To our knowledge this was the first experiment to demonstrate that an adaptive treadmill controller combining propulsion, spatiotemporal, and position-based control can be customized to target therapeutic outcomes such as increased propulsive force. Building on these experimental results, in Aim 3 we implemented the adaptive treadmill in the simulation framework by modifying the cost function to enable differential gains for propulsive impulse, step length, effort, and speed. We found that increasing the weight on the propulsive term in the simulated adaptive treadmill resulted in enhanced propulsion. Finally, in Aim 4 we incorporated unilateral weakness into the model with adaptive treadmill control to investigate responses of individuals with different post-stroke impairment levels. The predictive simulation results suggest that our modifications may improve the efficacy of the adaptive treadmill as a rehabilitation tool to increase paretic propulsion for stroke survivors with mild, moderate, and severe hemiparesis. Overall, the results of this dissertation represent an important step toward a comprehensive approach to designing custom treadmill-based therapeutic interventions for post-stroke gait rehabilitation. Future work should seek to further customize adaptive treadmill control through a human-in-the-loop optimization experiment and patient-specific models of stroke impairments.
EXAMINING NANOPARTICLE BASED SYSTEMS FOR APPLICATIONS IN MATERNAL/FETAL HEALTH
Irvin-Choy, N'Dea
The presence of pregnancy complications poses significant challenges for both the mother and the developing fetus, as available treatment options are limited due to safety and ethical considerations. Conditions like preeclampsia, fetal growth restriction (FGR), and placenta accreta exemplify pregnancy-induced disorders that lack effective remedies. As pregnancy progresses, these conditions worsen, leading to adverse consequences on the health of both the mother and the fetus. Consequently, emergency cesarean section delivery is often necessary, resulting in additional complications associated with premature birth for the newborns. Addressing the pressing need for enhanced maternal and fetal health during pregnancy, it is imperative to develop therapeutic advancements that can effectively treat pregnancy-related conditions while ensuring the well-being of the developing baby. In recent years, significant progress has been made in engineering nanocarrier systems for targeting various diseases, including cancers. The behavior of these nanocarriers in the body following systemic delivery is known to depend on factors such as size, shape, and surface chemistry. While researchers have harnessed this knowledge to develop powerful systems for treating ailments like cervical cancer, endometriosis, and HIV, the exploration of nanomedicine for pregnancy complications remains limited. The unique state of pregnancy introduces additional variables that influence NP distribution and design, including the dynamic physiology of the maternal reproductive system, the transport of nutrients and drugs through the placenta, and the development of the fetus. It is crucial to comprehend the impact of these factors on NP distribution to develop effective treatments that can support full-term pregnancies and improve the health of both mother and fetus. First, the biodistribution of gold-based nanoparticles (NPs) in pregnant mice was investigated following systemic delivery. Two different sizes of NPs, namely 15 nm gold nanoparticles and 150 nm diameter silica core/gold nanoshells coated with poly(ethylene) glycol (PEG), were intravenously administered to pregnant mice at gestational days (E)9.5 or 14.5. After twenty-four hours, the distribution of NPs in tissues was analyzed using inductively coupled plasma-mass spectrometry and silver staining of histological samples. The findings revealed a higher accumulation of NPs in the placentas compared to the embryos, with a greater delivery to these tissues observed at E9.5 than E14.5. Additionally, no adverse effects on fetal or placental weight were observed, indicating minimal short-term toxicity during early to mid-stage pregnancy. These results underscore the potential of further developing NPs as safe tools for targeted therapeutics delivery to reproductive tissues. The following study delved into the distribution of PEG-coated poly(lactic-co-glycolic) acid nanoparticles (PEG-PLGA NPs) in pregnant mice through vaginal delivery, as well as their short-term toxicity. Two types of NPs were employed: DiD-PEG-PLGA NPs loaded with fluorophores for cargo tracking, and Cy5-PEG-PLGA NPs incorporating tagged polymer for distribution analysis. DiD-PEG-PLGA NPs were administered on either gestational day (E)14.5 or 17.5, and after 24 hours, the distribution of cargo was examined in excised tissues and histological sections using fluorescence imaging. Interestingly, no variations in DiD distribution were found between the gestational periods. Therefore, Cy5-PEG-PLGA NPs were exclusively administered on E17.5 to assess polymer distribution in reproductive organs. The results showed the presence of Cy5-PEG-PLGA NPs in the vagina, placentas, and embryos, while DiD cargo was limited to the vagina. Furthermore, maternal, fetal, and placental weights remained unaffected by the NPs, indicating no immediate adverse effects on maternal or fetal growth. These findings suggest the potential of exploring vaginally delivered NP therapies for managing vaginal conditions during pregnancy. Lastly, the effectiveness of clindamycin-loaded PEG-PLGA nanoparticles (CLN-PEG-PLGA NPs) with different L:G ratios (50:50, 75:25, and 85:15) in inhibiting the growth of G. vaginalis, a pathogenic bacteria associated with bacterial vaginosis (BV) infections, was examined. G. vaginalis was cultured in suspension and on agar plates and treated with CLN-PEG-PLGA NPs of each L:G ratio. The growth of G. vaginalis was monitored using spectrophotometry or imaging at regular intervals over a 12-hour treatment period. The experiments demonstrated the effective inhibition of G. vaginalis growth in both suspension and on surfaces by CLN-PEG-PLGA NPs, irrespective of the L:G ratio. Interestingly, the bacterial growth inhibition did not significantly differ among the three L:G ratios, indicating that the ratio had minimal impact on short-term antibacterial treatment, likely due to similar total drug release from each formulation within the 12-hour period. While freely delivered clindamycin exhibited greater potency against G. vaginalis, it is important to note that CLN-PEG-PLGA NPs were able to decrease G. vaginalis growth in vitro. The foundational knowledge provided in this thesis holds utmost importance for the initial advancement of nanomedicines designed to address maternal-fetal health conditions. By incorporating the additional experiments mentioned earlier, researchers can assess the prolonged impacts of NP injections on pup development and growth. This comprehensive understanding will guide researchers in optimizing NP delivery and treatment efficacy while safeguarding the well-being of both the mother and the fetus. Such insights can aid in determining the most suitable administration routes, be it systemic or vaginal, to enhance NP delivery and promote successful treatment outcomes without compromising maternal or fetal health.
LARGE-SCALE RECONFIGURABLE SILICON PHOTONIC INTEGRATED CIRCUITS FOR RF PHOTONICS AND OPTICAL SIGNAL PROCESSING
Shawon, Md Jubayer
The demand for flexible wideband receivers that can be software-reconfigured for various bands and communication standards is paramount. However, implementing frequency-agile radio receivers faces significant challenges due to the limited frequency selectivity and tuning range of existing RF frontend solutions. Surface acoustic wave (SAW) filters, commonly used for off-chip filtering, are bulky, expensive, and inflexible. Researchers have explored alternative off-chip approaches such as MEMS switches and dual conversion receiver architectures, but these solutions often result in large size, weight, power and cost (SWaP-C), which is undesirable for both military and commercial wireless devices. Additionally, other solutions like RF MEMS or LTCC-based filters suffer from drawbacks such as large size, high voltage requirements, limited rejection for strong blockers, and limited tuning range. Active CMOS filters face limitations in tuning range and linearity, while mixer-first architectures using reciprocal mixing switches in nano-scale CMOS are constrained by losses and limited operating frequency. RF photonics, on the other hand, has emerged as a promising solution to overcome these challenges. It offers the advantages of large bandwidth and high tunability inherent to light. Traditional RF photonic systems have relied on discrete photonic components made of LiNbO3, which are costly, inefficient, and power-hungry. In contrast, silicon-based RF photonics leverages the mature CMOS processes developed in the semiconductor industry, enabling the integration of electronics with Photonic Integrated Circuits (PICs) on a large scale. Silicon photonics provides the potential for revolutionizing flexible wideband RF receivers by offering reliability, low manufacturing costs, and reduced energy consumption, all within a smaller form factor. However, achieving successful integration of Silicon Photonic Integrated Circuits (PIC) with RF electronics necessitates a cohesive design and verification platform capable of co-simulating both photonic and electronic circuits. The design tools for photonic integrated circuits (PICs) have evolved independently from electronic circuit simulation tools, resulting in a disconnection between these two domains. Bridging this gap is essential to enable efficient co-simulation of photonic circuits with interfacing electronic circuits. To address this, current work introduces a complex frequency chirp-based method for rapid frequency-domain simulation of PICs. The study investigates the trade-offs in selecting simulation parameters for achieving desired frequency response accuracy and simulation time, taking into account factors such as windowing and frequency chirp profile. The presented method can result in over 1000x improvement in simulation time of frequency sweeps of higher-order optical resonant circuits. In any flexible RF photonic system, the Electro-Optic (EO) modulator plays a crucial role as a key component, requiring both reconfigurability and high linearity. While traditional lithium niobate (LiNbO3) Mach-Zehnder Modulators (MZMs) have been widely used due to their superior linearity, silicon-based EO modulators have not achieved the same level of performance. To address this, the present work focuses on the experimental demonstration of a Ring Assisted Mach Zehnder Modulator (RAMZM) fabricated using a silicon photonic foundry process. This RAMZM modulator allows for linearization in the optical domain, and can be reconfigured to linearize around a user-specified center frequency and bias conditions, even in the presence of process, voltage, and temperature variations. The developed automatic reconfiguration algorithm, enabled by DACs, ADCs, TIAs, and digital configuration engine, linearizes the RAMZM modulator to achieve a spurious-free dynamic range (SFDR) exceeding 113 dB.Hz^2/3, assuming a shot-noise limited link. Moreover, a novel biasing scheme is introduced for RAMZMs, which significantly enhances the modulation slope efficiency, resulting in a tone gain of more than 13 dB compared to its standard operation. This reconfigurable electro-optic modulator can be seamlessly integrated into integrated RF photonic System-on-Chips (SoCs), offering the advantages of integration and cost-effectiveness. Furthermore, within a flexible RF photonic frontend, it is crucial for optical filters to have high tunability across a broad range of center frequencies and wide bandwidths. Additionally, these filters are expected to be frequency agile, meaning that their tunability and reconfigurability should be rapid and automatic. Therefore, this work demonstrates a software-configurable integrated optical filter capable of on-the-fly reconfiguration based on user specifications (filter topology, center frequency, bandwidth, and rejection). The digital configuration engine automatically reconfigures the filter with high fidelity even when process and temperature variations are present. The design is fabricated using AIM Photonics' Active SiP process, and I validated the reconfiguration algorithm for a second-order filter with 3dB bandwidth of 3 GHz, 2.2 dB insertion loss and >30 dB out-of-band rejection using only two reference laser wavelength settings. Moreover, in high-performance RF photonic systems, the incorporation of additional functionalities like optical mixing, true-time delay lines, frequency generation, and beamforming necessitates the use of dedicated silicon photonic IPs. Designing these Application-Specific Photonic Integrated Circuits (ASPICs) involves complex and time-consuming design cycles such as simulation, layout, fabrication, packaging, and testing, which require significant engineering effort and incur high costs. To address this challenge, the introduction of a general-purpose reconfigurable PIC holds the potential to revolutionize the field of integrated photonics, similar to the impact of electronic field-programmable gate arrays (FPGAs) in the electronics industry. Such a reconfigurable PIC would enable rapid design exploration and could cut the design cycle time from months to just a few hours. Therefore, in this work, general-purpose silicon photonics-enabled optical mesh structures have been designed and fabricated. These structures are large-scale mesh architecture fabricated using a CMOS-compatible SiP foundry process interfaced with on-chip monitors and an electronic hardware backend. A wide range of optical circuits is synthesized automatically within these meshes with the help of the electronic hardware backend.
Multiscale Rheological Constitutive Relations for Aggregating Suspensions
Jariwala, Soham
Aggregating colloidal suspensions can be encountered in many materials; examples include food products, biological fluids, printer inks, paints, and slurries. Describing the rheology of these suspensions remains challenging as their flow behavior directly connects to the mesoscale structure and aggregation kinetics. Transient flows in such suspensions show complex dynamics due to yield stress, viscoelasticity, and flow history dependence, i.e., thixotropy, and as a result can be classified as thixotropic elasto-viscoplastic (TEVP) materials. In the first part, an improved population balance-based rheological constitutive framework for polydisperse aggregating suspensions is derived by incorporating detailed models for orthokinetic and perikinetic aggregation and shear breakage processes. The framework accounts for critical properties such as dynamic arrest, viscoelasticity, kinematic hardening, thixotropy, and yield stress to generate a full range of TEVP responses. The model connects the rheological response to the structural descriptors such as the size distribution of agglomerates, mean sizes, fractal dimension and agglomerate volume fraction. Predictions are compared against a wide range of shear rheology measurements data for model thixotropic suspensions of fumed silica and carbon black, including large amplitude oscillatory shear (LAOS), as well as ultra-small angle neutron scattering under steady shear (Rheo-uSANS). A coarse-grained version of this model is also applied to understand blood rheology and we find that a population balance-based constitute model for blood is able to capture its characteristic transients for a wide range of physiologically relevant flow rates. The next contribution discusses how the combination of a population balance-based description of the aggregating particle microstructure and the use of nonequilibrium thermodynamics leads to the formulation of a model for fluid flow. The most significant contribution is the incorporation of specific measures of microstructure, such as moments of size distribution, into a thermodynamically consistent macroscopic continuum model of thixotropy and viscoelasticity. This approach enables a population balance-based model of the aggregation and breakage processes, as well as a conformation tensor-based viscoelastic description of the agglomerate network. The model is evaluated for shear and elongational flows offering consistent predictions for typical systems of aggregating particles. This first-principles, multiscale modeling approach resolves long-standing issues such as thermodynamic inconsistency and lack of connection to the fluid microstructure when describing the dynamics of aggregating suspensions. Furthermore, it has the potential to represent aggregating suspensions that are subjected to arbitrary three-dimensional flows. Finally, we extend the coarse-grained population balance-based constitutive model to include the ability to describe concentration inhomogeneities, which are often observed in particulate suspensions, in addition to the thixotropic effects. The description of the dynamics is further explored through numerical simulations of steady state and transient pressure-driven pipe flows. Although the capabilities of this modeling paradigm can be illustrated using these idealized flow simulations, additional microscopic theories, experimental measurements, and model refinement are needed for the full realization of this approach. The outcomes of this thesis establish a connection, for the first time, between the thermodynamically consistent modeling of rheological behavior of flow-sensitive aggregating suspensions at the continuum-level and a microscopically relevant, independently measured underlying microstructure. It simultaneously offers a systematic theoretical foundation to enable the development of more complex models that incorporate insights from novel experiments and microscopic simulations.
Rayleigh Criterion Applied to Radial Velocity Planet Searches
Ramirez Delgado, Victor Alejandro
The Rayleigh criterion determines the resolution limit of a periodogram, which is the minimum frequency separation required to barely resolve two sinusoids. Neglecting to consider the Rayleigh criterion may result in a false interpretation of a long-period signal or a spurious claim that two closely spaced periodogram peaks represent two distinct physical processes. This thesis demonstrates how the Rayleigh criterion can help astronomers avoid false positives caused by artifacts of uneven time intervals between observations. We use the Rayleigh criterion to show that the frequency separation between planet 55 Cncd and the stellar activity cycle is too small to distinguish the two phenomena based on published radial velocity data alone. We also demonstrate that the radial velocity signal of contested planet HD99492~c cannot be separated from zero frequency according to the Rayleigh criterion. Finally, we demonstrate that a cubic polynomial is a better fit to the long-term RV variability of Barnard's star than a sinusoid with a frequency that is statistically indistinguishable from zero. This work concludes that astronomers searching for periodic signals should consider the Rayleigh resolution criterion as part of their discovery validation.
Intimate Partner Violence and the Criminal Legal System
Derr, Kate
The paper examines the role of the criminal-legal system in relationships in which the participant experience intimate partner violence. The criminal-legal system has greatly expanded since the 1980s and disproportionately affects the Black community and other marginalized groups. This study analyzes the life histories of intimate partner violence (IPV) victims and offenders and their interaction with the criminal-legal system by using semi-structured interviews with 18 participants. Analysis of the interviews was conducted utilizing a Black feminist criminology framework to understand the interlocking nature of race, gender, and class and its effects on public policy effectiveness. My analysis uncovered three emerging themes among the research participants: IPV is one problem among many, victims were arrested when they sought help, and some women use the criminal-legal system to escape. This study found a relationship between criminal-legal system impact and multiple IPV relationships. Combined with the themes uncovered in this analysis, this research supports policy interventions that advocate for alternative methods to policing in intimate partner violence relationships, promote robust social safety nets, and provide expanded support to domestic violence programs that offer drug and alcohol addiction services, housing and job assistance, and mental health support.
A Tale of Energy-Burdened Cities: Connecting the Low-Income Housing Tax Credit to Energy Insecurity
Clase, Cara Marie
In the United States, urban areas are one of the most energy-insecure spaces with energy-cost-to-income ratios (i.e. energy burdens) as high as 25%. This is more than twice the 10% standard energy insecurity studies use to distinguish highly energy-burdened households. Impoverished, urban areas tend to have residents that live in older and less energy-efficient housing that requires more energy - and thus money - to operate. Examining financial and infrastructural variables of energy insecurity, this dissertation takes a deeper look at the exogenous variation in infrastructure created by the Low-Income Housing Tax Credit (LIHTC): a credit that incentivizes housing developers to build or renovate housing for low-income renters. Specifically, a two-way fixed effects regression model is used to investigate the impact of LIHTC housing supply on the energy burdens of urban PUMAs and ConsPUMAs. The analysis found that PUMAs with more LIHTC units, especially newly-built units, had a significantly negative relationship with energy cost and energy burden in multiple model specifications. Additionally, the analysis also found strong evidence that infrastructure-centered programs like the Weatherization Assistance Program have a significantly negative relationship with energy cost and burden.
SIMILAR MICROBIOME COMPOSITIONS OF NYMPHAL BLACKLEGGED TICKS (IXODES SCAPULARIS) INFECTED AND UNINFECTED WITH BORRELIA BURGDORFERI IN DELAWARE
Casey, Tyler
Pathogens can be influenced by their host’s microbiome, and this can have consequences for pathogen dynamics. Therefore, characterizing the microbiome of hosts, particularly vectors, may help explain pathogen transmission patterns and facilitate the development of novel transmission-blocking approaches. Borrelia burgdorferi is a bacterium that is transmitted by blacklegged ticks (Ixodes scapularis) in the eastern and upper midwestern United States and causes Lyme disease in humans. Borrelia burgdorferi has been hypothesized to be susceptible to exclusion from the midgut of blacklegged ticks by other bacteria, however, blacklegged tick microbiomes have not been characterized across the entire geographical range of the tick. Here we compare the microbiomes of nymphal blacklegged ticks infected and uninfected with B. burgdorferi collected at three sites across Delaware, a high-incidence state for Lyme disease. Infected and uninfected ticks did not differ in alpha diversity of their microbiomes and had similar microbiome compositions after removing B. burgdorferi from the analysis. Tick microbiomes varied among sampling locations in terms of both alpha and beta diversity, demonstrating that the tick microbiome can differ over small spatial scales. We also found at least one tick infected with the emerging pathogen B. miyamotoi. We compare our results to the growing literature of blacklegged tick microbiome studies and suggest that there is currently only limited evidence that tick microbiomes consistently influence the probability of ticks being infected with B. burgdorferi in nature.
NEUROBIOLOGICAL SEQUELAE OF CHILDHOOD MALTREATMENT: POTENTIAL MECHANISMS TO RISKY, IMPULSIVE AND SELF-DESTRUCTIVE BEHAVIORS
Bounoua, Nadia
Childhood maltreatment has been identified as a robust risk factor for a myriad of poor psychological and health outcomes. Despite these advancements, significant gaps in our understanding still remain regarding mechanisms through which maltreatment confers risk for psychosocial problems that persist across the lifespan. To address this, recent theoretical models have advocated for dimensional approaches that specify how unique dimensions of adversity relate to psychological processes and neurobiological alterations that may clarify the equifinality and multifinality of poor outcomes following exposure to adversity. Based on these theories, the overarching objective of this dissertation was to examine psychological and neurobiological correlates of Childhood Deprivation (e.g., neglect) and Threat (e.g., physical abuse) in adulthood. First, I provide an overview of the existing literature, and present preliminary results from three completed studies that served as a foundation for my proposed dissertation project. Informed by the National Institute of Mental Health’s Research Domain Criteria (RDoC), the specific aims of my dissertation project are to investigate how childhood maltreatment relates to risk-taking behaviors via: a) trait affective and motivational processes and b) brain activation during affectively-manipulated tasks of inhibitory control. Results provide initial support for dimensional models of childhood maltreatment. We found that childhood experiences of neglect and abuse were differentially associated with affective and inhibitory control processes observed at a behavioral and neural level. Specifically, findings suggest that disruptions in inhibitory control and both negative and positive processes are important in understanding self-regulation failure in the context of Childhood Deprivation, whereas negative affective processes appear to be particularly important in the context of Childhood Threat. Findings are discussed in the context of existing literature of childhood maltreatment, potential implications for clinical interventions, and areas for future research.
BERM MIGRATION AND MUNITIONS MOTION UNDER SCALED STORM EVENTS
Chapman, Emily
From the time of the First World War until 1970, unused munitions used to be disposed into the sea. A century later, these unused munitions are still becoming exposed onshore endangering the public and marine life. The migration and exposure of these unused munitions in the nearshore under extreme events is poorly understood. In the United States, coastal regions are home to about 128 million people or nearly 40% of the whole population. Coastal erosion will continue to worsen as storms intensify due to sea level rise driven by climate change. As a result of the erosion of natural beach defenses, infrastructure and populations close to coastal areas will endure flooding. It’s crucial to predict the migration of geomorphological features such as berms in order to understand the erosion processes. The goal of this study is to take an initial look at how to bring these two topics, berms and munitions, together by studying the processes that drive munitions of variable density to migrate and bury in the berm. A large-scale experiment at Institut national de la recherche scientifique (INRS) in Quebec City, Canada was conducted to study these processes. Mantoloking Beach, NJ and Hurricane Sandy were scaled to replicate the beach profile and wave conditions, respectively. One hundred fifty-five munitions of variable density were deployed for this experiment. Three cases from the experiment were analyzed for this study: a low-forcing case, a high-forcing case, and a longer-period wave case. In addition to the forcing conditions established during each case, the root mean square wave height was calculated to understand the hydrodynamics for each of the 3 cases. The force going into the swash zone was compared to the accretion and erosion found in the berm. The greater the force going in, the greater the accretion or erosion found in the berm. Less dense munitions had greater net migrations than their denser counterparts. Munitions deployed on the berm crest migrated onshore while the munitions starting on the berm face migrated offshore.
Whose voice is heard?: stakeholder participation in crisis decision-making teams in higher education institutions during COVID-19
(University of Delaware, 2023) Michaud, Michael Stephen
Many organizations across the United States were severely impacted by the COVID-19 pandemic, including institutions of higher education. Campus leaders needed to make decisions about closing campuses, increasing financial constraints, shifts in research, and changing class modalities. Past research shows that one preferred method for making decisions during an organizational crisis is using teams of decision-makers, although there has been little research focused on the composition of these teams. Others advocate for the inclusion of various stakeholders in the decision-making structure; however, it is not known how often stakeholders, including faculty, below-director-level staff, and students, are included in decision-making. This dissertation asks three questions: (1) What stakeholders are included on crisis decision-making teams at organizations of higher education during the COVID-19 pandemic? (2) What institutional factors influence stakeholder participation in crisis decision-making teams at organizations of higher education during the COVID-19 pandemic? (3) How were stakeholder voices included in decision-making teams during the COVID-19 decision-making process? The first phase, answering the first two research questions, utilizes a content analysis and survey of 150 US higher education institutions to investigate the inclusion of stakeholders in COVID-19 decision-making teams. Institutional data from the Carnegie Classification of Institutions of Higher Education was used to compare differences based on institution types and sizes. The results show about half of the decision-making teams included stakeholders. Faculty are the most likely to be included and students are the least likely. There is no statistically significant association between any institutional characteristic and stakeholder inclusion. Larger decision-making teams are more likely to include stakeholders than smaller teams. The second phase, answering the third research question, utilizes 20 semi-structured interviews of decision-making team members. Results show faculty are most likely to be included and considered in the decision-making process. While students are less likely to be included, there are ways for their perspectives to be included in decision-making. Staff member perspectives were the least included in decision-making. These findings are the first examination of stakeholder inclusion in higher education crisis decision-making and show that inclusion is limited, despite previous research showing the benefits. They serve as a foundation for future research and offer considerations for practitioners. ☐ The first phase, answering the first two research questions, utilizes a content analysis and survey of 150 US higher education institutions to investigate the inclusion of stakeholders in COVID-19 decision-making teams. Institutional data from the Carnegie Classification of Institutions of Higher Education was used to compare differences based on institution types and sizes. The results show about half of the decision-making teams included stakeholders. Faculty are the most likely to be included and students are the least likely. There is no statistically significant association between any institutional characteristic and stakeholder inclusion. Larger decision-making teams are more likely to include stakeholders than smaller teams. The second phase, answering the third research question, utilizes 20 semi-structured interviews of decision-making team members. Results show faculty are most likely to be included and considered in the decision-making process. While students are less likely to be included, there are ways for their perspectives to be included in decision-making. Staff member perspectives were the least included in decision-making. These findings are the first examination of stakeholder inclusion in higher education crisis decision-making and show that inclusion is limited, despite previous research showing the benefits. They serve as a foundation for future research and offer considerations for practitioners.
A Preliminary Evaluation of the Feasibility, Acceptability, and Health Behavior Outcomes of a Community-Based Group Health Coaching for Cancer Survivors Program: A Mixed Methods RE-AIM Study
Berzins, Nicole J.
In the United States, there are currently more than 18 million people living with and beyond cancer with that number expected to increase to 22 million by 2030. This growing population often experiences additional long-standing health challenges, including long-lasting side effects from treatment, an increased risk of cancer recurrence, and having or developing a comorbidity such as diabetes or cardiovascular disease. This can have impacts throughout the lifetime in both physical and mental health, as well as quality of life. It has been found that a substantial cancer burden may be prevented through behavioral lifestyle modifications, such as increasing physical activity, improving diet habits, improving duration and quality of sleep, and managing stress. However, adherence to these behaviors remains low. Health coaching, a process by which trained coaches help clients establish sustainable behavior changes that align with their strengths and values through client-centered interactions and goal setting, has been shown to be effective at eliciting improvements in the aforementioned behaviors in a variety of populations, including cancer patients and survivors. While typically delivered in a one-on-one format, it can be costly, requires more trained coaches, and is not time efficient to reach a large number of people. As such, health coaching in a group format has started to emerge, however, less is known about this mode as it is still in its early stages of development. Therefore, the purpose of this dissertation was to (1) explore existing group health coaching interventions targeting cancer survivors, specifically examining program composition and measured outcomes, (2) to develop and assess the feasibility and acceptability of a group health coaching program for cancer patients and survivors in a community-based setting using a videoconferencing platform, as well as to assess the preliminary effects of the program on a variety of behavioral lifestyle factors, and (3) to evaluate the program using the RE-AIM (Reach, Effectiveness, Adoption, Implementation, and Maintenance) framework. A scoping review of the literature was first conducted. A systematic search strategy was used between October 2021 and February 2023 to identify intervention studies focused on group health coaching with cancer patients and survivors. Seven studies met the criteria. These studies focused on physical activity, diet, weight loss, or some combination thereof utilizing group health coaching by itself or as one component of an exercise and/or diet intervention. There was a wide range of measured outcomes, which loosely grouped into: feasibility/acceptability; physical activity/exercise; body composition and biomarkers; diet; distress, quality of life, fatigue; and other. Overall, studies were found to be feasible and showed positive results for weight loss, diet, and quality of life. Findings for physical activity, distress, and fatigue were mixed. Additionally, variability was found in many of the group health coaching components. This review suggests group health coaching in the cancer patient and survivor population is still in the nascent stages. However, these studies were deemed highly feasible and satisfactory to the participants, and positive outcomes were associated with these interventions. Future research should consider expanding upon these findings with more robust studies. Guided by the findings of the scoping review, a community-based group health coaching program was developed. Six group health coaching sessions over a three-month period addressing the topics of stress management, physical activity, sleep, and diet were offered to cancer patients and survivors across the state of Delaware using a videoconferencing platform. Sessions were facilitated by health coaches trained through a National Board for Health and Wellness Coaching accredited training program. Data was collected using a convergent mixed methods approach. Surveys were sent pre- and post-intervention on topics including physical activity, eating habits, perceived stress, anxiety, depression, sleep, and quality of life, followed by post-program focus groups and in-depth interviews. Data on recruitment, attrition, attendance, fidelity, retention, safety, and barriers and facilitators to implementation were also assessed. Survey results were analyzed using repeated measures multilevel modeling. Inductive thematic analysis was used to analyze qualitative data. Overall, this intervention was considered feasible to implement and found acceptable by both participants and health coaches. A total of 26 participants attended an average of 74% of coaching sessions. Coaching participants also noted a moderate increase in total weekly physical activity minutes (p= 0.032, d=0.50). A small increase was seen in weekly moderate-vigorous physical activity frequency (p=0.045, d=0.39). Additionally, a moderate increase was found in functional wellbeing (p<0.001, d=0.50). This suggests group health coaching may be a feasible and acceptable way to promote behavior change in cancer patients and survivors, particularly for physical activity and functional wellbeing. The group health coaching program was then evaluated using the RE-Aim framework. The main outcomes of this study were mapped onto the five dimensions of RE-AIM. As mentioned, 26 participants attended an average of 74% of coaching sessions with an overall fidelity rate of 89.7%. Participants were more likely to be female, White, older, have a higher educational attainment, and have had breast cancer than the state population. The biggest adaptation included extending the time of sessions. The primary support to implementation included the use of NBHWC trained coaches while the primary barrier was the videoconferencing platform. While some challenges for recruitment and implementation were noted, the program will transition to a completely community-based project going forward. In summary, group health coaching with the cancer population was feasible to implement and found to be acceptable to cancer patients and survivors in the state of Delaware. It was successfully implemented within a community setting and may be particularly effective for changing physical activity levels and physical functioning scores. Provided in this format, the cancer patients and survivors are provided with peer support beyond what the coach alone can provide and allows for ongoing learning and connection with others, despite participants having different cancers and being in different places in their journey. Going forward, the program will be refined based on feedback from participants and coaches before being implemented within Cancer Support Community Delaware locations across the state.
Coastal Hydrodynamics and its Interaction with Structure and Sediment
Tsai, Benjamin
The rise in sea levels and the increase in extreme weather events due to climate change have emerged as significant issues for society. It is imperative to account for their effects when designing coastal structures and formulating resource management strategies. Rapid coastal morphodynamic changes during storms, such as beach erosion and scouring around critical infrastructure like bridge piers, are of particular interest. To address these concerns, this study employs advanced computational fluid dynamics techniques within a multi-phase flow framework, with the aim of deepening our understanding of complex physical processes. This research first evaluates the capability of turbulence-resolving simulations for a near-prototype scale wave flume experiment under random waves, investigating key processes during wave-swash interactions for two stages of beach profiles observed during a storm event. The findings indicate that large bottom shear stress (represented by the Shields parameter), horizontal pressure gradient (the Sleath parameters), and a robust turbulence-berm interaction (characterized by high turbulent kinetic energy directly contacting the bed) leading to significant sediment transport events are caused by intense interaction between backwash and incoming breaking waves. These results provide valuable insights into the underlying causes of berm erosion. This study proceeds to utilize the Eulerian two-phase model, SedFoam, to simulate the initiation of scour beneath a 2D pipeline and the subsequent backfilling process. It has been demonstrated via laboratory experiments that the seepage flow underneath the pipeline, called piping, initiates the scouring process. Previous simulations based on single-phase models required artificial adjustments to account for the onset of scour. In contrast, this study demonstrates the capability of the two-phase model in quantitatively simulating piping, validated through comparisons with a series of laboratory measurements. To further confirm the model’s capability to simulate the backfill process, we artificially descent the pipeline into the scour hole. This represents an idealized representation of the complex sinking process that occurs during scour. The resulting burial depth due to backfill aligns with predictions derived from empirical formulas. SedFoam is further applied to simulate wave-induced scour around a vertical cylinder. Through detailed model validation and grid convergence study, we provide evaluations for future scour simulations concerning the choice of turbulence modeling methods and grid resolutions. Specifically, a higher resolution and turbulence-resolving model, such as large-eddy simulation, is preferred to capture key vortices, namely the horseshoe vortex and lee-wake vortices. A higher resolution and turbulence-resolving model are also suggested for scour simulations, as they can predict a more accurate scour hole in both depth and width. For more efficient Reynolds-averaged simulation, the $k$-$\omega$ (2006) model yields reasonable predictions for scour hole depth development. However, it tends to over-predict the scour hole width. The present study establishes a simulation framework, based on a multi-phase flow methodology, for selected coastal applications. It is suggested that future research efforts focus on enhancing the modeling of dune erosion by integrating more extensive soil mechanics formulations. Additionally, improvements to wave runup and breaking predictions in regional-scale models are recommended.
Deep learning predictive modelling for electronic health records
(University of Delaware, 2023) Gupta, Mehak
With the digitization of health records over the last two decades there is a large amount of health records data collected electronically. This data provides unprecedented research opportunities to build clinical prediction models to estimate future health risks. Working with EHRs is known to be challenging due to their volume, different data types, and quality issues. The complex characteristics and quality issues in EHR can be listed as: 1) large feature space, 2) unequal lengths of medical histories, 3) a different number of observations (per patient), 4) irregular intervals between visits, and 5) missing values. Tackling these issues is the fundamental task to efficiently utilize the massive EHR data to build clinical prediction models. ☐ The non-linear complexity and temporal relationships in electronic health records (EHRs) limit the capability of traditional machine learning methods to perform clinical predictive tasks with high accuracy. In this work, we focus on using deep learning techniques to capture complex patterns in EHR data and address its data quality issues to build deep learning clinical prediction models with improved accuracy. We present a hybrid sequential deep learning model to capture static and longitudinal patterns in EHR data. To address missingness and irregular time intervals in EHR time-series data, we propose a model to interpolate and extrapolate values to perform concurrent imputation and prediction. We also propose a prediction model design to learn from different lengths of medical histories and provide the varying lengths of future time-series prediction. Lastly, we provide open source software with the collection of various cleaning, pre-processing, modeling, and evaluation techniques to build clinical prediction models using open-source EHR data. Our proposed models and techniques can be utilized for different disease prediction tasks using EHR data although we primarily focus on their application in childhood obesity prediction.
Deep Ocean Circulation Changes During the Mid-Pleistocene Transition
Symes, Emily
The Mid-Pleistocene Transition (MPT), occurring between ~1250 to 700 Ka (1.25 to 0.7 Ma) marks a fundamental change in Earth’s climate system when the glacial cyclicity of Earth changed from 41 to 100 Kyr. This observed change cannot be explained due to variations in solar insolation only suggesting changing internal climate dynamics might have driven the transition. The South Pacific represents the largest fraction of the Southern Ocean and hence an important target region for studying internal climate dynamics during the MPT. Here, we use sediment core U1541 (54˚13’S, 125˚25’W, 3604 m) collected during the International Ocean Discovery Program (IODP) Expedition 383 to investigate changes in deep ocean circulation and the role of these changes played in solidifying the conditions of the MPT. In this thesis, we present an authigenic Nd isotope (expressed as Nd) time series from Site U1541 from 1500 – 500 ka. Nd shifts can be interpreted as tracking changes in the mixing proportions of two water mass end members, unradiogenic Atlantic (Nd ~-13.5) and radiogenic Pacific sourced waters (PSW, Nd ~-4). In our record, the proportions of Atlantic and Pacific sourced water masses fluctuate across glacial cycles with glacials reflecting more Pacific source water, indicative of weakened Meridional Overturning Circulation (MOC). Across the MPT, we have observed three periods of increased PSW influence at ~1250 ka (Marine Isotope Stage (MIS) 38), ~900 ka (MIS 22), and ~650 ka (MIS 16) interpreted as periods of a more complete breakdown in MOC than other glacial periods. The ~1250 ka event predates previous findings which suggested ~900 ka was the first event of such magnitude. Comparison of our results with the ice volume (using  18Osw, a direct proxy of ice volume or sea level change) record for ODP 1123 (Elderfield et al., 2012) shows there is a strong correlation between the observed deep ocean circulation changes and global ice volume suggesting there is a mechanistic link between the two variables. We propose this link is a shift in the nature of Antarctic glaciers from terrestrial sourced to glaciomarine. The influx of freshwater into the surrounding oceans from melting iceberg off these glaciomarine glaciers can produce low density lenses of water near the Subantarctic front and has the potential to destabilize the water column producing perturbations in deep ocean circulation as observed in our record.
Residence Time and Salinity Impacts on Chromium Speciation and Mobility in Soils of Varying Iron and Manganese Oxide Contents
Sricharoenvech, Piyapas
Chromium (Cr) contamination in soils has inevitably become a threat to human health and the environment over several decades due to its excessive use in industries such as leather tanning, wood preservation, and stainless steel production. Chromium is a redox-reactive metal, predominantly present in two stable forms as Cr(III) and Cr(VI). Chromium(III) is less toxic and less mobile, while Cr(VI) is carcinogenic and can travel a great distance in the environment. The stability and toxicity of Cr are strongly related to its speciation, driven by several soil components (e.g., iron (Fe) oxides, organic matter, manganese (Mn) oxides) as well as environmental factors (e.g., redox conditions, porewater composition). Several studies have indicated that Cr mobility and availability decrease over time through aging. However, the long-term aging effect on Cr speciation and mobility in contaminated soils is still unclear, especially in soils containing high content of Mn oxides, which can persistently oxidize Cr(III) to the readily mobile Cr(VI). This is of particular concern, especially when most soil worldwide is currently threatened by global climate change. Increasing storms and rainfalls may enhance Cr leaching, while inundation and saltwater intrusion of contaminated coastal soils may mobilize Cr through changes in redox conditions and ion competition. A better understanding of how aging and water salinity impact Cr cycling is needed to predict long-term environmental effects and potential remediation strategies under the impacts of global climate change. The objectives of this work are (1) to determine the residence time effect on Cr speciation and stability in soils and (2) to investigate how Cr in contaminated soils responds to changes in water salinity and redox conditions. Throughout this work, a systematic characterization of soil samples (pre- and post-reactions) was conducted utilizing batch incubations, sequential extractions, and desorption experiments, as well as advanced spectroscopic tools (e.g., bulk and microfocused X-ray absorption techniques) to identify changes in solid-phase Cr speciation and mobility. Chapters 1 and 2 investigate residence time and water salinity impacts on Cr speciation and mobility in soils. Two soils with varying Fe and Mn contents were reacted with Cr(III) and Cr(VI), as in dissolved CrCl3 and K2CrO4, and allowed to age up to 180 days. Alkaline digestion and sequential extractions were utilized to identify changes in soil Cr(VI) concentrations and Cr partitioning, while bulk and microfocused X-ray absorption techniques were employed to determine shifts in Cr speciation and spatial distribution over time. The results indicated that the speciation of Cr in aged soils was strongly related to the added Cr oxidation state and the presence of Mn oxides, which oxidized Cr(III) to Cr(VI). The increase in more stable Cr phases was observed in all aged soils; however, the aging effect was more pronounced in low Mn soils (LM), in which soil Cr(VI) content decreased over time. The results also suggested the persistence of Cr(VI) in high Mn soils (HM). Reacting Cr-aged soils with artificial seawater resulted in extremely high Cr release (up to 12 mg L-1) in all Cr-aged soils, except Cr(III)-aged LM soils, possibly due to the presence of Cr(VI) outer-sphere complexes. Chromium(VI) remained in these sediments after seawater treatment, suggesting that Cr may be released in case of multiple cycles of exposures. Chapter 3 investigates Cr speciation and mobility in existing Cr-contaminated coastal urban soils impacted by water salinity and redox conditions. Chromium-contaminated soil samples were collected from a contaminated site in Wilmington, Delaware. Bulk and microfocused X-ray absorption near edge structure (XANES) spectroscopy and sequential extractions were utilized to determine Cr speciation and stability. In addition, desorption experiments and batch incubations were conducted to examine how Cr in these soils responds to changes in water salinity and redox conditions. The results revealed that, although the soils contained very high levels of Cr (up to 4320 mg kg-1), Cr mobility remained very low under non-flooded conditions due to the abundance of chromite (~52%) and Fe-Cr hydroxide coprecipitates (~44%). Chromium(II) was also identified in the soils by bulk and microfocused XANES, potentially derived from the waste materials at the sampling site. Seawater and anoxic conditions resulted in lower Cr release compared to freshwater and aerobic conditions. Three to eight times more Cr was released under aerobic conditions versus anaerobic conditions in the freshwater versus saltwater, respectively. This work improves an understanding of residence time and water salinity impacts on Cr speciation and mobility in Cr-contaminated soils and, more importantly, raises some concerns regarding a potential long-term health risk from Cr release due to sea level rise and global climate change. Further studies should focus on assessing how salinity and redox fluctuations impact Cr cycling and potential health hazards due to the potential Cr release from these contaminated soils.
Power Embodied: Pectoral Crosses in Early England and their Pre-Christian Background
Vause, Rachael
Far removed from the bodies they once adorned, and the graves from which they were unearthed, golden cross pendants, richly inlaid with garnets, sit behind glass in various museums in Great Britain. Like many museum objects, crosses from seventh-century England are disembodied from the people who wore them and from the context of their life as things. Bereft of contextual images from grave sites or excavations, both publications and museums tend to privilege the frontal, visual aspect of these pendants. This dissertation attempts to reconcile the duality between human and material culture and body and mind through a study of personal adornment. The people of fifth- and sixth-century England arrayed their bodies with jewelry that expressed status, heritage, and personal style and provided amuletic protection in life and in the grave. By the end of the seventh century, after the introduction of Christianity at the end of the sixth, jewelry all but disappeared from the cemetery record. Assessment of such changes to personal adornment, burial practices, or grave goods has focused on larger abstract concepts of political, social, or religious transition; less consideration has been given to the body as the primary driver of human action. Cognitive and phenomenological methodologies provide a new perspective in interpreting cultural changes like the transition from a non-Christian to a Christian paradigm. New concepts are internalized within the body, which includes the brain and its environment, rather than by a disembodied mind processing and acting autonomously. Through a case-study of the wearable cross, this dissertation will demonstrate the ability of embodied objects to change entrenched cultural notions about the mind/body relationship. This study begins with the engagement between jewelry and the wearer, including the bodily motivations for adornment, the affective properties of design and materials, and the effects on memory and recall. It then explores anxieties regarding protection from the supernatural in life and in death, as well as societal functions of personal adornment. With the penetration of the image and sign of the cross into seventh-century England, it will posit the translation of concerns for protection from pre-Christian amulets to the Christian cross. Additionally, it will examine the cognitive effects of Christian ritual as well as bodily interaction between cross pendants and their owners. Finally, it will demonstrate the eventual disappearance of the wearable cross from the cemetery record in the eighth century as suggestive of one of the first major shifts in attitudes toward the material world and the body. More than a mere replacement of amulets, the cross represents a sensorial need for contact between power-object and wearer as belief systems overlapped between the sixth and seventh centuries. This bodily relationship provides a richer understanding of the people of early medieval England and the glittering ornaments they carried with them in life and beyond.
USING EVALUATION TO DETERMINE THE EFFECTIVENESS OF THE LEADELAWARE PROGRAM AT CREATING AGRICULTURAL LEADERS IN THE STATE OF DELAWARE
Volk, Jennifer
The LEADelaware Program is a leadership development program for individuals working in the agricultural and natural resources fields in Delaware and has been in operation since 2005. This Education Leadership Portfolio (ELP) examines the problem of knowing too little about the effectiveness of the LEADelaware Program to date and the program’s current lack of capacity to perform evaluation functions. This ELP established two goals: 1) increased understanding of the effectiveness of the LEADelaware Program to date and 2) increased evaluation information for program improvement and an improved evaluation framework. To achieve Goal 1, three strategies were employed. First, to learn more about the problem, a literature review was conducted (Artifact 1). Then, to understand how program strategies led to the ultimate program goal, a logic model was developed for the program which created the foundation of an evaluation plan for this ELP (Artifact 2). To gather evidence on program effectiveness, data were gathered from five sources: program materials and summarized existing evaluation data (Artifact 3), past directors (Artifact 4), members of the Advisory Committee (Artifact 5), members of the Curriculum Committee (Artifact 6), and program alumni (Artifact 7). Qualitative and quantitative methods were used to gather data on program effectiveness and to develop recommendations for program improvement. Data gathered in Artifacts 3 through 7 provide evidence of program effectiveness related to the achievement of early program objectives. There was not, however, substantial evidence that the program achieved intermediate program objectives to use new knowledge, skills, and networks to collaboratively address agricultural issues. Additionally, evidence collected suggests that past program directors lacked the time to devote to the task of evaluation due the administrative structure of the program. To achieve Goal 2, two strategies were employed. First, the findings and recommendations from the five data collection artifacts (Artifact 3 through 7) were used to refine and revise a logic model for the LEADelaware Program. This logic model was subsequently used to update the evaluation matrix for the program going forward (Artifact 8). Additionally, a slide deck of recommendations on program improvement was prepared for consideration by the Advisory and Curriculum Committees. These recommendations were classified into seven categories: 1) program administration; 2) roles and functions of the Advisory Committee; 3) Curriculum Committee considerations (which includes agricultural content, leadership content, and leadership activities); 4) program components; 5) communication/ coordination; 6) target audience, application, and recruitment; and 7) embedded evaluation. The leaders at the University of Delaware College of Agriculture and Natural Resources (UDCANR) and Delaware Department of Agriculture (DDA), along with current co-directors and the Advisory and Curriculum Committees for the program are provided the recommendations within this ELP to facilitate program planning. Given this ELP’s information on effectiveness and recommendations for program improvement, stakeholders might consider developing a strategic plan for the LEADelaware Program. Given this ELP’s information on effectiveness and recommendations for program improvement, stakeholders should consider developing a strategic plan for the LEADelaware Program.

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