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Design and Radiometric Modeling of a Portable EEM Fluorescence Sensor for ppb-Level Detection of Pesticide Mixtures in Water
No full textThesis (Master's)--University of Washington, 2025According to the U.S. Geological Survey (USGS), pesticide contamination of American waters is widespread, with typical samples containing mixtures of 10 to 20 active compounds. Recent studies show that agricultural runoff and seasonal application patterns are two of the most common sources of this contamination. Environmental monitoring studies help improve understanding of the distribution and persistence of pesticides in natural water systems. Enhanced detection tools are critical for environmental monitoring studies that target data collection and the analysis of water quality data. Traditional pesticide measurement methods include solvent extraction and chromatographic separation, which introduce problems such as: 1) high cost per sample, 2) slow turnaround time, and 3) limited suitability for field deployment. Recent advancements in fluorescence spectroscopy have allowed for the development of various portable measurement techniques in different applications. However, environmental agencies are still using laboratory-based analysis rather than portable optical measurement tools, which demonstrates that there is significant room for improvement in this field. The detection of pesticides using excitation-emission matrix (EEM) fluorescence requires accurate photon throughput calculation using component-based or radiometric modeling techniques. This thesis is a study of the design, modeling, and validation of an EEM fluorescence system based on multi-wavelength excitation theory. The system was designed, modeled, and evaluated in pesticide detection applications using three representative compounds: zeta-cypermethrin, myclobutanil, and glyphosate. The compounds were tested at five concentration levels to characterize the system across different detection scenarios. When compared to model predictions, the experimental results showed detection limits of 10-100 ppb for strongly fluorescent pesticides, approximately one order of magnitude above predicted values due to lower LED power than modeled. Based on the results and validation from the radiometric model, the use of compact EEM fluorescence systems in portable applications has potential to improve the frequency and cost-effectiveness of pesticide screening
Essays on Housing Supply, Affordability, and Policy Incentives: Causal and Quantitative Approaches to Modeling Housing Market Dynamics and Policy Evaluation
No full textThesis (Ph.D.)--University of Washington, 2025This dissertation advances the economic understanding of a dual challenge confronting policymakers in many cities with high rent burdens: housing affordability and supply constraints. It provides empirical evidence on the effectiveness of housing policies in addressing these challenges through a combination of descriptive analyses and causal inference methods that exploit spatial and temporal variation in housing and related data. The empirical analyses employ advanced difference-in-differences research designs developed in recent econometric literature. Complementing the empirical work, the dissertation develops a quantitative urban model of affordable housing, augmented with simulation exercises, to examine how such policies redistribute households, housing development, and prices across space, and to evaluate the welfare implications of these redistributions. Future work will structurally estimate this model using empirical data to assess the effectiveness of alternative affordable housing policies in expanding supply and improving affordability. The first chapter examines inclusionary zoning (IZ) policies—an increasingly common tool in many cities that use subsidies and tax exemptions to incentivize the inclusion of income-restricted units in market-rate developments. Focusing on a long-running IZ program in Seattle, we study how such policies shape the spatial distribution of new housing and affect neighborhood outcomes. Although program requirements are uniform, variation in local market conditions generates heterogeneous responses from developers and landlords. Leveraging policy changes over time and detailed rental microdata, we identify a key trade-off: in higher-income neighborhoods, rent discounts for subsidized units are larger, but developer participation is more sensitive to reductions in policy generosity. IZ also lowers nearby rents in lower-income areas but raises them in higher-income areas, consistent with direct competition in the former and building-induced neighborhood changes in the latter. The second chapter develops a quantitative spatial equilibrium model of an urban housing market that allows for features uncovered in the first chapter. The model includes heterogeneous households and profit-maximizing developers to evaluate the general equilibrium effects of an inclusionary zoning policy. The model extends Ahlfeldt, Redding, Sturm, and Wolf (2015) by explicitly modeling developers’ building and participation decisions under endogenous amenities and heterogeneous housing quality. Developers choose whether to construct market-rate or MFTE housing and determine building intensity based on local market rents and program parameters. On the demand side, high- and low-skilled households select residential locations based on wages, amenities, and rents, with low-skilled households eligible for rationed MFTE units. Amenities evolve endogenously with neighborhood housing stock, generating feedback between development and residential demand. The model is closed with equilibrium conditions that ensure market clearing in market-rate housing, rationing in MFTE housing, and dynamic consistency in housing stock evolution. Simulations illustrate how the MFTE program can influence developer entry, clustering of new construction, and access to high-amenity locations for lower-income households, thereby providing a framework to quantify the welfare and spatial redistribution effects of affordable housing policy. The third chapter examines a growing source of pressure on rental housing supply in recent decades: the expansion of investment properties used for short-term vacation rentals. I exploit the economic shocks of the COVID-19 pandemic as a natural experiment to study how property owners reallocated investment homes between short-term rental (STR) markets, such as Airbnb, and long-term rental (LTR) markets. Before the pandemic, many homeowners increasingly used Airbnb to rent investment properties to tourists rather than residents, raising concerns about the platform’s impact on housing affordability in supply-constrained markets. Using a continuous difference-in-differences design, I estimate that a 1 percentage point (pp) greater exposure to pre-pandemic tourism demand led to a 1.2–2.1 pp decline in Airbnb listings on average. I also provide evidence that Airbnb hosts shifted to LTR markets, as reflected in short-run increases in LTR rents during 2020. The effects were strongest among owners of two- to three-bedroom properties in areas with higher ownership costs—such as mortgage payments and property taxes—suggesting possible heterogeneous responses driven by homeowner liquidity constraints or financial leverage
Multimodal Implementation Research on Primary Health Care Services in sub-Saharan Africa: Implementation Outcomes, Service Readiness and Costs
No full textThesis (Ph.D.)--University of Washington, 2025Primary health Care (PHC) serves as the cornerstone for achieving universal health coverage (UHC), one of the health-related targets in the 2030 Sustainable Development Goals (SDGs). PHC facility managers play a key role in ensuring quality of care by overseeing daily operations, managing human resources, and effectively implementing national PHC guidelines. This dissertation reports findings on implementation outcomes, service readiness, and costs through multimodal implementation research on strategies to improve PHC services in sub-Saharan Africa (sSA). Two of the three research Aims (Aims 2 and 3) are embedded within a district-based implementation and dissemination program in central Mozambique's PHC settings, called the Integrated District Evidence-to-Action (IDEAs) program for neonatal mortality reduction, implemented from 2016 to 2020. IDEAs applied a system-level Audit and Feedback (A&F) strategy that included three core components: routine facility and district readiness assessments, district-level biannual health facility performance review meetings, and targeted facility support through supportive supervision to help health facilities implement their micro-interventions developed during the biannual meetings. There were nine cycles of IDEAs. For Aim 1, this study synthesized implementation strategies and outcomes of evidence-based management interventions for PHC managers in sSA through a systematic review. Nine case studies from six countries—Ethiopia (3 studies), South Africa (2), and one each from Botswana, Kenya, Tanzania, and Zambia—were identified. The interventions included evidence-based training programs, peer-to-peer learning, electronic systems for monitoring management practices, and supportive supervision. Common implementation strategies included training and education, coaching and mentoring, knowledge sharing through learning collaboratives, interactive and continuous learning, and A&F using routine data. Interventions were implemented using more than one strategy. Acceptability was a consistent positive implementation outcome reported, with management effectiveness improving in areas such as financial and resource management, organizational climate, and human resource management.
For Aim 2, we assessed effectiveness of management training and IDEAs intervention on improving basic obstetric and neonatal service readiness in PHC facilities. We found that IDEAs intervention's effectiveness in enhancing service availability was highest when health facility managers in the intervention sites had received management training, with an average increase of 11.1 points out of 100 per year (95% CI: 0.7 to 21.5, p=0.037), after adjusting for potential confounders. Hence, capacitated PHC managers were better able to optimize a system-level A&F strategy to improve PHC services, bundling management training with A&F strategies could enhance effectiveness.
For Aim 3, a mixed costing approach (gross and microcosting) was used to estimate the cost of implementing IDEAs. We found the total cost of the program across 12 districts over five years (2016-2020), discounted to 2020 US dollars was USD 495,323 (23.8%) allocated to capital costs and 36,693; A&F meetings made up 8,255 (22.5%), with vehicle purchase as the main cost driver; Targeted support were divided into two parts, district focused and facility supervision. The performance review meetings occurred biannually, each lasting five days, resulting in a total of 10 days per year per district. The average hours spent per year attending A&F meetings for the seven key positions from health facilities, district and province was 2320 hours (80 hours per person annually per district), while five district staff conducting supervision spent a total of 240 hours per year (60 hours per person annually per district). We were not able to estimate staff hours for routine data collection since it was contracted to local agencies. This study provides new insights into the cost of implementing iterative system-level A&F strategies in low-income settings.
As demonstrated in this dissertation, we applied a multimodal implementation research approach — using evidence synthesis to improve health system coordination and management, strengthen management capacity, and incorporate economic evaluation — helped identify pathways for the systematic integration of national PHC guidelines, offering insights for improving PHC services. The key takeaway is that while implementation research is valuable for improving healthcare systems, there is a significant knowledge gap regarding what works for PHC management in sub-Saharan Africa and the costs associated with implementing a system-level A&F strategy. This dissertation aims to spread knowledge about strengthening health systems to improve primary healthcare and achieve universal health coverage
Discovering the potential of renewable energy from palm oil mill effluent: Environmental impacts, opportunities, and challenges in the development of biogas and bio-cng
No full textBackground: Indonesia, as the largest palm oil-producing country in the world, will also produce palm oil mill effluent (POME). POME production from palm oil processing is faced with many environmental problems from the release of emissions. The development of new renewable energy in Indonesia needs to be increased to reduce dependence on fossil energy and commit to reducing greenhouse gas emissions. The purpose of this study is to discuss the potential for new renewable energy from the utilization of POME biogas energy and how the environmental impacts are caused as well as the opportunities and challenges of developing EBT from POME. Methods: This research analysis method is LCA, and descriptive. Findings: Total CO2 emission (eq) of biogas production from POME is -24.62 Kg CO2 (eq), eutrophication is -0.2188 Kg PO43- (eq) and acidification is 0.00552 Kg SO2 (eq). Biogas production from POME in Jambi Province is not optimal and has not been used optimally, the process efficiency is low, and the profitability is low. Conclusion: There is a need for a concept to utilize biogas energy that does not only focus on electrical energy but also as a renewable energy source such as bio-CNG which has wider use. Novelty/Originality of this article: The novelty of this research lies in the comprehensive analysis of the utilization of Palm Oil Mill Effluent (POME) as a renewable energy source that is not only limited to electrical energy but also includes the potential conversion of POME into bio-CNG as a more flexible and sustainable alternative
Impacts of the COVID-19 Pandemic on the Social/Emotional Development of Children and Adolescents
No full textMaster of Education (MEd)This research explores the social/emotional and mental health impacts of the COVID-19 pandemic and the resulting lockdown and remote schooling policies on children and adolescents. Research from around the world regarding students from preschool to high school was examined. Four themes were identified: general impacts of the pandemic on all students, differences in the impacts based on the age of the students, patterns pertaining to socioeconomic status, and the ramifications for students with disabilities. The paper goes on to examine how practices at a specific action site (a Title 1 school in Western Washington) could be aligned with recommendations made in the research, and then explores implications for future research and transformed practice in the schools
Reimagining Search: Exploring the Past, Present, and Designing the Future
No full textThesis (Master's)--University of Washington, 2025Current search paradigms, while efficient for simple lookup tasks, fail to support the complex, contextual, and exploratory information-seeking behaviors that characterize human cognition. This thesis investigates how search interfaces might be redesigned to better align with natural human information-seeking patterns through spatial, social, and exploratory interaction paradigms.The research establishes three conceptual metaphors—library, marketplace, and Klondike—as a theoretical framework for understanding different dimensions of human search behavior. The library metaphor emphasizes spatial organization and adjacency relationships that enable serendipitous discovery. The marketplace metaphor highlights comparison processes and social dimensions of information evaluation. The Klondike metaphor addresses exploration of unknown territories where users cannot predict what they might find.
Through iterative design exploration, these metaphors were integrated into NEXPLORE, an augmented reality search application that demonstrates spatial navigation through contextually-relevant information environments. NEXPLORE transforms search from keyword-based retrieval into environmental interaction, where users can look at objects and naturally inquire about them through voice, gesture, and spatial navigation. The system demonstrates this integration through a restaurant search experience that seamlessly transitions between marketplace-style comparison, library-style exploration, and frontier-style environmental awareness.
The design employs a design-as-research methodology, treating prototyping as a form of inquiry that reveals insights about spatial search that could only emerge through experiencing alternative interaction paradigms. Key innovations include environmental context awareness that anticipates user needs, persistent spatial information organization that supports learning over time, and multimodal interaction that accommodates diverse cognitive styles.
This research contributes both theoretical frameworks for understanding human information-seeking behavior and practical demonstrations of how search interfaces can leverage spatial intelligence, contextual awareness, and natural interaction to create more intuitive and effective information experiences. The work points toward a future where finding information feels less like interrogating a database and more like exploring a rich, responsive environment
Sensory Experience Kit for Families at Woodland Park Zoo
No full textThesis (Master's)--University of Washington, 2025Everyone experiences fluctuations in sensory sensitivity—sometimes seeking more stimulation, other times needing less—but these shifts often go unnoticed. In outdoor spaces like zoos, fluctuating factors such as weather, crowds, and sensory input can make it especially hard for children to regulate how they feel and respond. The Sensory Experience Kit was created to help families visiting Woodland Park Zoo navigate sensory highs and lows, promoting comfort, focus, and deeper engagement with nature. The kit includes four themed booklets, a caregiver guide, and a sensory map. Each booklet is tied to a habitat and offers sensory-based activities organized into low, medium, and high intensity levels. Activities encourage children to engage through movement, touch, and observation. Kits are housed in Zoomazium, the zoo's play area for kids, and occasionally offered at the zoo entrance for wider reach. The project was shaped by a front-end evaluation with caregivers and a formative evaluation with families with target age group children. Feedback guided the design and refinement of accessibility, functionality, and content design. By recognizing sensory balance as a universal need, this project offers a more inclusive way to support children's well-being in nature-based environments. It also highlights the importance of tailoring sensory support to specific environments
The Future in Ruins: Leveraging Principles of Preservation to Reclaim Vacant Buildings as Public Space in Downtown Seattle
No full textThesis (Master's)--University of Washington, 2025Vacant buildings, deteriorating infrastructure, and shrinking public realms are symptoms of ongoing pandemic-era challenges and underfunded downtowns, contributing to broader crises of human disconnection and declining ecological networks. In Seattle, unreinforced masonry (URM) buildings embody this intersection of challenges, presenting seismic vulnerability and urban vacancy while offering unique opportunities for adaptive preservation and public space revitalization. This thesis reimagines preservation as a proactive, adaptive practice that moves beyond architectural integrity to embrace social, cultural, and ecological values. By integrating strategic deconstruction and on-site material reuse, preservation becomes a tool for regenerating urban “ruins” into community-rooted public spaces. Framed as a dynamic dialogue between past and future, this thesis proposes an approach that expands preservation practice beyond static artifact-guarding to an integrated, community-driven strategy that strengthens urban infrastructure across built, environmental, and social dimensions. Through this lens, former vacant sites are transformed into accessible public spaces that foster community cohesion, ecological health, and climate resilience. Applying this framework to a vacant URM building in Belltown, the thesis employs physical modeling and material analysis to develop design proposals that reimagine the site as a hybrid cultural-ecological ‘commons.’ This work offers a replicable model of adaptive preservation that leverages material continuity and spatial transformation to address urban challenges and promote more sustainable, equitable urban neighborhoods
Race, Reform, and Recalls: The Movements for and against “Progressive” Prosecutors
No full textThesis (Ph.D.)--University of Washington, 2025In the United States, prosecutors are locally elected and enjoy significant discretion at the front-end of the criminal legal system, including over charges, bail recommendations, and plea deals. Advocates for criminal legal reform have increasingly focused on the power of the prosecutor as a potential instrument of reform. The term “progressive prosecutor” is used to refer to those who are elected on campaign pledges to combat mass incarceration and its racial disparities while pursuing accountability for system harm and police violence. Progressive prosecutors have been elected in growing numbers since 2016, a timeframe scholars tie to Black Lives Matter (BLM). Existing research examines individual progressive prosecutor offices and their aggregate effects. This study marks the first known empirical investigation of the movements for and against progressive prosecutors. Through a novel prosecutor database, media data, and campaign finance archives, I analyze the actors, strategies, and goals in the contest over the power of prosecutors and their potential to advance reform.
The findings indicate that although progressives made gains at the ballot box and contributed to reform, their efforts have been stifled by highly organized and well-funded countermovements. I argue that these attacks on progressive prosecutors constitute novel movement repertoires – including extra-electoral challenges to remove elected officials from office or constrain their power outside of regularly scheduled elections – to thwart racial justice efforts following BLM. I show how these countermovements employ the language of law, order, and public safety reminiscent of earlier backlashes against racial justice in the United States, including following Reconstruction and the 1960s Civil Rights Movement. I also suggest that campaigns against progressive prosecutors provide templates for future efforts to oust officials with whom right-wing politicians and donors disagree. In this way, the movements for and against progressive prosecutors shed light not only on the potential and limits of current criminal legal reform efforts, but also on our contemporary era defined by racialized polarization and democratic contraction
Designing Huge Colloidal Quantum Dots for Scalable & Deterministic Placement of Single-Photon Emitters
No full textThesis (Ph.D.)--University of Washington, 2025Colloidal quantum dots (QDs) have been widely explored as light-emitting materials due to their tunable optical properties, high quantum yield, and solution-processability. In quantum photonics, individual QDs can serve as single-photon emitters that are critical for quantum technologies, including communication, computing, cryptography, and metrology, where discrete photons function as qubits. However, conventional emissive QDs, including Cd-, In-, Pb-, and Hgbased materials, typically have diameters below 10 nm due to the Bohr radius limitation and synthetic feasibility. Even with core/shell architectures, where materials like CdS or ZnS encapsulate the core QDs to enhance stability and emission, they rarely exceed 20 nm. This size constraint creates a fundamental challenge in integrating QDs into photonic devices, as optical cavities and resonant structures often have mode volumes on the micrometer scale, leading to poor spatial overlap and limiting efficient light-matter interaction. To address this size mismatch while maintaining desirable optical properties, this dissertation explores three complementary approaches. First, a machine learning framework is developed to refine CdSe and InP QD syntheses by extracting synthetic parameters from literature, addressing data inconsistencies, and predicting optimized reaction conditions. Using data augmentation and predictive modeling, this method enables precise control over emission wavelengths and sizes, complementing experimental efforts to design QDs with targeted properties (Chapter 3). Next, Chapter 4 explores silica encapsulation as a method to enlarge QDs and enhance their stability in air. By coating QDs with a protective silica shell, the particle size increases to around 90 nm. This enlargement enables deterministic patterning of emissive particles onto planar substrates while preserving single-photon emission. Finally, a stepwise CdS shelling strategy is introduced in Chapter 5 to synthesize colossal CdSe/CdS QDs with diameters exceeding 100 nm, significantly expanding the range of QD-based light emitters. Using electrohydrodynamic inkjet printing, these QDs are patterned into large arrays and deterministically positioned into nanobeam cavities for scalable quantum light sources. Beyond their advantages for particle placement, colossal QDs exhibit exceptional stability under ambient excitation, making them well-suited for studies requiring sustained high excitation conditions. Their large size also provides a platform for investigating nanocrystal growth mechanisms, as structural evolution can be directly visualized using electron microscopy with greater clarity than smaller QDs allow. Together, the approaches presented herein advance the synthesis and integration of QDs for scalable quantum photonics by combining data-driven synthesis optimization, silica shelling for size enlargement, and the development of colossal core/shell QDs. These approaches address key challenges in QD-based single-photon emitters and provide strategies for improving stability, deterministic placement, and scalability. Beyond photonics, the findings contribute to a deeper understanding of QD growth and stability, supporting their broader application in quantum information science and next-generation optoelectronics