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Tunable Electrical and Fatigue Performance of Carbon Nanotube-Embedded Bottlebrush Elastomers via Compositional Control
No full textBottlebrush elastomers (BBEs) are promising for flexible and wearable electronics due to their mechanical resilience. Incorporating conductive nanofillers such as carbon nanotubes (CNTs) enables the tuning of their electrical properties. This work studies the electrical properties of CNT–bottlebrush elastomer composites by varying polydimethylsiloxane (PDMS)/crosslinker ratios and CNTs loadings. Building on established synthesis methods, this study investigates how compositional changes affect conductivity, sensitivity, and fatigue behavior. Our results show a composition-dependent trade-off between electrical and mechanical fatigue performance, offering insights into tailoring these composites to meet specific performance requirements in next-generation soft electronics
Can Hydrogen Be Produced Cost-Effectively from Heavy Oil Reservoirs?
No full textThe potential for hydrogen production from heavy oil reservoirs has gained significant attention as a dual-benefit process for both enhanced oil recovery and low-carbon energy generation. This study investigates the technical and economic feasibility of producing hydrogen from heavy oil reservoirs using two primary in situ combustion gasification strategies: cyclic steam/air and CO<sub>2</sub> + O<sub>2</sub> injection. Through a comprehensive analysis of technical barriers, economic drivers, and market conditions, we assess the hydrogen production potential of each method. While both strategies show promise, they face considerable challenges: the high energy demands associated with steam generation in the steam/air strategy, and the complexities of CO<sub>2</sub> procurement, capture, and storage in the CO<sub>2</sub> + O<sub>2</sub> method. The novelty of this work lies in combining CMG-STARS reservoir simulations with GoldSim techno-economic modeling to quantify hydrogen yields, production costs, and oil&ndash;hydrogen revenue trade-offs under realistic field conditions. The analysis reveals that under current technological and market conditions, the cost of hydrogen production significantly exceeds the market price, rendering the process economically uncompetitive. Furthermore, the dominance of oil production as the primary revenue source in both methods limits the economic viability of hydrogen production. Unless substantial advancements are made in technology or a more cost-efficient production strategy is developed, hydrogen production from heavy oil reservoirs is unlikely to become commercially viable in the near term. This study provides crucial insights into the challenges that must be addressed for hydrogen production from heavy oil reservoirs to be considered a competitive energy source
Essays in Labor Economics and the Economics of Education
No full textThe dissertation consists of two papers on the economics of education and labor economics. In the first paper, I estimate the impact of school closures on students. School closures are a widespread and persistent issue in the US, displacing hundreds of thousands of students each year due to demographic shifts, outmigration, and performance-based policies. Although closures are often justified as a means to provide access to better-resourced schools, they frequently cause disruption and backlash, particularly among disadvantaged communities. Using Texas administrative data and a difference-in-differences approach, this study examines both short- and long-term effects of public school closures from 1998 to 2015. I find that closures—mostly driven by demographic and financial pressures—lead to immediate declines in test scores and increases in absences and disciplinary actions, especially among secondary students and those from economically disadvantaged families. While test scores tend to recover, behavioral disruptions persist. In the long run, closures reduce high school graduation, college enrollment, and employment rates, and lead to a drop in earnings by the mid-20s. This study highlights the need for caution in using closure as an education policy tool. In the second paper, I examine the labor market implications of the gender reversal in educational attainment. Women have overtaken men in educational attainment in the US and many developed countries, reversing a long-standing gender gap. While earlier research attributes this reversal to higher psychic costs in education for men, this paper formally explores the implications of gender differences in psychic costs of schooling on education, skills, and wages using Becker's human capital framework. Introducing behavioral measures as a proxy for psychic costs, the study shows that women have consistently lower psychic costs, which explains one-third of the gender education gap. However, this sorting results in a reversal of the gender gap in cognitive skills when conditioning on education—women have lower cognitive skills than men at the same educational level. While non-cognitive traits (e.g., behavior) do not directly affect wages beyond education, cognitive skills have strong labor market returns, and their unequal distribution across genders due to differential educational sorting amplifies the gender wage gap. Controlling for these skills reduces the wage gap by 7–12\%. The findings highlight the potential problems associated with gender comparisons at the same educational level, particularly when various skills are not available
Essays on Trade and China's Economy
No full textThis dissertation consists of two essays on trade and China’s economy. In the first essay, motivated by China’s recent economic slowdown, the relocation of labor-intensive industries, and an aging population, this paper examines how demographic forces shape China’s economic growth and trade patterns. Empirical analysis indicates that countries with a larger working-age population share experience higher productivity growth and a higher investment share of GDP. Building on these findings, I develop and calibrate an overlapping generations trade model with three key features: age-varying abilities to generate ideas that drive knowledge accumulation, age-varying saving behaviors affecting capital accumulation, and an Eaton-Kortum trade framework that includes both Heckscher-Ohlin and Ricardian comparative advantage. By comparing the baseline stationary equilibrium to a hypothetical one where China’s fertility and survival rates align with those of the rest of the world, I find that a higher fertility rate leads to higher productivity levels in the final year and results in greater consumption, as more workers generate more ideas. In contrast, a lower survival rate results in reduced productivity while also increasing consumption, driven by a decrease in desired savings due to the shorter lifespan. Overall, productivity is primarily driven by fertility, while capital per person is largely driven by the survival rate, as it affects desired savings. In the second essay, I investigate the decline in China’s trade share of GDP since 2007. To understand the underlying causes, I develop a multi-sector, multi-region Ricardian trade model to quantify the forces driving changes in China’s trade share of GDP from 2002 to 2015. The model features three main types of time-varying shocks: productivity shocks, trade cost shocks, and labor mobility cost shocks. These shocks affect China’s trade through comparative advantage and specialization. I calibrate the model and conduct structural accounting decompositions. The results indicate that changes in productivity and trade costs for both China and foreign regions together account for about 87% of the change in China’s trade share of GDP. From 2002 to 2007, the decrease in China’s international trade costs and the growth in foreign productivity were the main factors driving the increase in trade share. From 2007 to 2015, China’s productivity growth became the primary factor reducing the trade share. Moreover, in contrast to the earlier period, China’s international trade cost changes also contributed to the decline in its trade share
Validation of the Sensal Health MyAideTM Smart Dock Medication Adherence Device
No full textBackground: Electronic monitoring adherence devices (EAMDs) are increasingly being utilized in various healthcare settings to track medication adherence. Objective: To determine the accuracy of the Sensal Health MyAide&trade; Smart Doc in capturing dose removal from the vial, specifically the time of dose removal and the number of pills removed for each actuation of the device. Methods: This validation study compares the device&rsquo;s recording of dose withdrawals from a prescription vial by simulated patients against reference documentation reported using MS Forms by the participants. Three participants completed a 4-day study consisting of two non-consecutive 1 h sessions per day encompassing six actuations from the prescription vial to be captured by the Sensal Health MyAide&trade; Smart Dock after their informed consent was obtained. Statistical analysis included percent agreement and Cohen&rsquo;s kappa assessing agreement between user-reported data and electronic measurement data recorded by the MyAide&trade; Smart Dock. Outcome measures included confirmation of the specific user, time of dose removal (&plusmn;1 min), and the number of pills withdrawn. Results: Three subjects were recruited to provide data for a total of 144 actuations. The study found perfect 100% agreement across the number of pills withdrawn and specific users withdrawing the pills and 99% agreement for the time of administration. The Cohen&rsquo;s kappa values for the outcome measures were 1.00 (95%CI [1.00, 1.00]) for the number of pills dispensed and specific user and 0.993 (95%CI [0.990, 0.996]) for the time of administration. Conclusions: This study found that the Sensal Health MyAide&trade; Smart Dock can accurately record the time of administration, the number of pills dispensed, and the identity of the user dispensing the pills
Effects of Hydrocodone Rescheduling on Pain Management Practices Among Older Breast Cancer Patients
No full textHydrocodone, a commonly prescribed opioid, was rescheduled from Schedule III to Schedule II in October 2014, imposing stricter prescribing regulations. While prior studies have examined its effects in general populations, its impact on breast cancer patients remains unclear. We evaluated changes in pain management among older women with early-stage breast cancer following this policy change. Using SEER-Medicare data from 2011&ndash;2019, we identified a retrospective cohort of 52,792 women aged &ge;66 years. We assessed trends in the use of hydrocodone, non-hydrocodone opioids, NSAIDs, and antidepressants before and after rescheduling. Hydrocodone use declined from 55% to 40%, while non-hydrocodone opioid use increased from 43% to 50%. Multivariable logistic regression adjusted for demographic and clinical factors confirmed a significant decrease in hydrocodone use (AOR: 0.81, 95% CI: 0.75&ndash;0.86) and an increase in non-hydrocodone opioid use (AOR: 1.25, 95% CI: 1.21&ndash;1.30). Hydrocodone dosage also declined, while non-hydrocodone opioid dosages remained stable. No significant changes were observed in NSAID or antidepressant use. These findings suggest that hydrocodone rescheduling significantly altered opioid prescribing patterns, reducing hydrocodone use and prompting a shift toward alternative opioids. Further research is warranted to evaluate the appropriateness and outcomes of such shifts in cancer pain management
The Untapped Potential of Ascon Hash Functions: Benchmarking, Hardware Profiling, and Application Insights for Secure IoT and Blockchain Systems
No full textHash functions are fundamental components in both cryptographic and non-cryptographic systems, supporting secure authentication, data integrity, fingerprinting, and indexing. While the Ascon family, selected by the National Institute of Standards and Technology (NIST) in 2023 for lightweight cryptography, has been extensively evaluated in its authenticated encryption mode, its hashing and extendable-output variants, namely Ascon-Hash256, Ascon-XOF128, and Ascon-CXOF128, have not received the same level of empirical attention. This paper presents a structured benchmarking study of these hash variants using both the SMHasher framework and custom Python-based simulation environments. SMHasher is used to evaluate statistical and structural robustness under constrained, patterned, and low-entropy input conditions, while Python-based experiments assess application-specific performance in Bloom filter-based replay detection at the network edge, Merkle tree aggregation for blockchain transaction integrity, lightweight device fingerprinting for IoT identity management, and tamper-evident logging for distributed ledgers. We compare the performance of Ascon hashes with widely used cryptographic functions such as SHA3 and BLAKE2s, as well as high-speed non-cryptographic hashes including MurmurHash3 and xxHash. We assess avalanche behavior, diffusion consistency, output bias, and keyset sensitivity while also examining Ascon-XOF&rsquo;s variable-length output capabilities relative to SHAKE for applications such as domain-separated hashing and lightweight key derivation. Experimental results indicate that Ascon hash functions offer strong diffusion, low statistical bias, and competitive performance across both cryptographic and application-specific domains. These properties make them well suited for deployment in resource-constrained systems, including Internet of Things (IoT) devices, blockchain indexing frameworks, and probabilistic authentication architectures. This study provides the first comprehensive empirical evaluation of Ascon hashing modes and offers new insights into their potential as lightweight, structurally resilient alternatives to established hash functions
Robust Parameter Designs Constructed from Hadamard Matrices
No full textThe primary objective of robust parameter design (RPD) is to determine the optimal settings of control factors in a system to minimize response variance while achieving a desirable mean response. This article investigates fractional factorial designs constructed from Hadamard matrices of orders 12, 16, and 20 to meet RPD requirements with minimal runs. For various combinations of control and noise factors, rather than recommending a single &ldquo;best&rdquo; design, up to the top ten good candidate designs are identified. All listed designs permit the estimation of all control-by-noise interactions and the main effects of both control and noise factors. Additionally, some nonregular RPDs allow for the estimation of one or two control-by-control interactions, which may be critical for achieving optimal mean response. These results provide practical options for efficient, resource-constrained experiments with economical run sizes
Increasing Parents’ Knowledge of Activities for Their Youth with Intellectual Disabilities (ID)
No full textBackground: Parents of youth with intellectual disabilities (ID) need to find community and recreational activities that engage them mentally, physically, and psychologically. These activities, if attended regularly can have an impact on their child’s life in ways that parents may not recognize as important but find that overtime, their consistent attendance can support them in their integration into the community on their journey to adulthood. Purpose: This research aimed to determine if activities provided by the Families CAN program are making a difference in the lives of youth with ID through their continuous attendance at events and activities. It investigated the type of events and activities that youth with ID utilized the most from 2020-2023 and determine what future activities parents want their youth with ID to participate in. Further analysis of this program examined how parents rated the quality of information and services provided from 2020-2023. Finally, parents described their experiences based on their interactions with staff and their satisfaction with the program. Method: The two research methods utilize mixed methods descriptive analysis. Data was collected from de-identified archival files of activities attended and surveys of parents from this local community organization. The summarization of the events and activities were categorized into Family, Social, and Work Experiences. Results: Research Question One found that youth with ID attended more Family Unity Experiences than Social and Work Experiences. Research Question Two found that parent responders wanted social recreational and fitness programs for their youth with ID in addition to wanting more educational programs for themselves. Research Question Three found that parent respondents rated the quality of the information and services with excellent ratings. Research Question Four revealed that parent responders described their experiences through positive statements about the Families CAN program based on their interactions with staff and their satisfaction with the program. Conclusion: The findings showed that youth with ID attended more engagement activities that provided Family Unity Experiences, which benefited the entire family. Receiving positive satisfaction reports from parents is important to a program’s success; however, parents should recognize the benefits of their child’s attendance in these programs, which give children skills and provide a foundation to support them in their journey to adulthood
Upholding Gender Equity: Title IX Coordinators' Experiences Supporting Pregnant and Parenting Postsecondary Students
No full textBackground: This study employs narrative inquiry and the Contexts for College Change framework to explore the experiences of Title IX coordinators (TIXCs) at fouryear public U.S. institutions in supporting pregnant and parenting students (PPS). Purpose: While Title IX mandates protections, accommodations, and institutional support for PPS, implementation varies. Prior research identified macro-level institutional factors influencing PPS support such as enrollment size and U.S. region, but little is known about the micro-level experiences of administrators working directly with PPS. Methods: I conducted seven semi-structured interviews with TIXCs from four distinct types of four-year public institutions. I analyzed the data thematically and presented findings through vignettes and cross-narrative themes. Results: TIXCs perceive their role in PPS support as advocacy for students, institutional compliance, and defending educational rights. Their approaches are shaped by implicit and explicit factors within four contexts of college change: campus, higher education, external stakeholders, and society. Seven key themes emerged: (1) PPS awareness shaped by personal experience, (2) identity-driven motivation and approaches, (3) support, (4) campus norms, (5) resource availability, (6) policy challenges, and (7) emotional strain. Conclusion: The findings illuminate the complexities of TIXCs’ experiences in supporting PPS. Positioned at the intersection of policy and practice, TIXCs are pivotal in advocating for PPS rights and advancing gender equity in education. These insights offer valuable guidance for strengthening institutional practices that promote PPS retention and degree completion