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Advances in Proximal Inference for Continuous Exposures, Estimation of Ill-Posed Regression, and Non-Inferiority Assessment in Active-Controlled Trials
No full textThesis (Ph.D.)--University of Washington, 2025This dissertation advances proximal inference methods for continuous exposures and ill-posed regression problems, alongside non-inferiority assessment in active-controlled trials.An introduction to the topics is provided in Chapter 1. Chapter 2 develops a unifying framework for non-inferiority evaluation in active-controlled trials, where placebo arms are unavailable, enabling systematic comparison of existing methods in terms of type I error, power, and robustness to transportability misspecifications. Chapter 3, motivated by the analysis of immune correlates of protection in COVID-19 vaccine trials, extends the proximal inference framework to identify and estimate the mean outcome under modified treatment policies, enabling causal analysis of continuous exposures in the presence of unmeasured confounding. Chapter 4 addresses the challenge of estimating ill-posed nuisance functions in proximal inference and related settings, developing a novel finite-sample analysis of kernel-based regularized adversarial stabilized estimators and establishing conditions under which debiased, influence-function-based one-step estimators for a broad class of estimands, achieve root-n consistency and asymptotic normality. Together, these contributions support more robust inference in complex causal problems with unmeasured confounding or design constraints
Living on Winter’s Edge: Snow Ecology of Large Mammals in Northern Ecosystems
No full textThesis (Ph.D.)--University of Washington, 2025Climate change is rapidly reshaping snowpacks around the world, with dramatic impacts on wildlife. My dissertation explored the role of snow in shaping predator–prey relationships and movement ecology, focusing on large mammals in the northern United States of America and Canada. Chapter 2 used winter fieldwork to quantify how specific snow properties influence the sink depths of tracks made by predators (bobcats, cougars, coyotes, and wolves) and their sympatric ungulate prey (caribou, deer, moose). Using generalized additive models, breakpoint regression, and animal morphology, I found that near-surface snow density is the most significant predictor of sink depth, with different thresholds for predators and prey. I identified "danger zones" where snow conditions impede ungulates’ movement more than predators, providing a framework to predict the impacts of climate-driven snow changes on predator–prey dynamics. Chapter 3 applied an entirely different methodological approach to investigate whether these danger zones factor into apex predator habitat selection. Using GPS collar data for cougars, wolves, mule deer, and white-tailed deer, I found that snow depth and density significantly affect predator movement, with predators selecting for areas with either shallow or with deep, dense snow. Kill-site investigations for cougar-killed deer indicated similar snow preferences. In Chapter 4, I examined winter movements from an ungulate perspective, using GPS collared data from five moose populations across their entire latitudinal range. I found that, even in winter, high temperatures cause moose to adjust behavioral patterns and alter habitat selection, potentially forgoing foraging opportunities in favor of thermal refuge. These changes were most dramatic in southern moose and may be a contributing factor to recent moose range contraction along their southern margins. Finally, Chapter 5 integrated physically based snow modeling with climate projections to predict how changing snowpacks will alter predator–prey interactions. I focused on two apex predators, cougars and wolves, and their primary prey, mule deer and white-tailed deer, under two mid-century climate change scenarios (SSP2-4.5 and SSP5-8.5). My results showed significant declines in snow-mediated advantages for predators, with a reduction in both the duration and extent of snowpack conditions that favor predator movement (as identified in Chapter 3). These changes are expected to have disproportionate impacts on apex predators, potentially leading to shifts in predator home ranges, prey densities, and ecosystem dynamics. Collectively, these chapters underscore the profound effects of climate-driven changes in snowpack dynamics on large carnivore and ungulate behavior, with potential for significant shifts in predator–prey interactions across the Northern Hemisphere
Temperature spikes and marine heatwaves trigger rapid larval development in Pisaster ochraceus (Echinodermata: Asteroidea)
No full textIn the North Pacific, marine heatwaves (MHWs) have been increasing in intensity, frequency, and duration, and have resulted in large ecological shifts in the rocky intertidal. The sea star Pisaster ochraceus, a keystone species in the rocky intertidal, has seen declines of up to 90% associated with MHWs. This study focused on the effect of MHWs and temperature “spikes” on the larval stage of P. ochraceus. Larvae were reared in control ambient (CA) temperatures of 11.0-16.0℃, constant control (CC) temperatures 11.0-11.7 (±1℃), and MHW temperatures that rose to a maximum of 20°C (±1℃) over a 12-day period and remained high for 40 days before returning to ambient conditions. Morphological measurements and development of larvae from each treatment were obtained once a week. Linear regression and PCA analysis were conducted to summarize and visualize the morphological data. Linear regression revealed strong correlations between total length and total width and stronger correlations between total length and preoral process length for CA and MHW treatments. PCA showed that at 15 days post fertilization (dpf) and 22 dpf, the morphological space occupied by MHW larvae differed significantly from both control treatments, while the two control groups (CA and CC) were similar. By 29 dpf, the morphological space occupied by larvae in all three treatments diverged significantly. The separation of CC larvae in morphological space from CA larvae was evident. Spicule formation and the appearance of brachiolar arms and adhesive disk appeared much earlier for MHW larvae than for larvae in the control treatments (CA and CC). This study shows that both MHWs and temperature spikes can trigger rapid larval growth and development, potentially impacting settlement through their effects on the development of critical juvenile structures
Impacts of the COVID-19 Pandemic on the Social/Emotional Development of Children and Adolescents
Get PDFMaster 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
Impacts of the Religious Right Agendas on LGBTQ+ Students
Get PDFMaster of Education (MEd)This paper examines the impact of the religious right's policy activism on the health and well-being of LGBTQ+ students. It also explores how educators can collaborate with advocacy groups and how state policies can ensure that each district implements LGBTQ+ inclusive curricula uniformly. Gender identities are particularly vulnerable in 2025, and culture wars are intensifying. I aim to identify modifiable factors that can promote positive school environments throughout our state and ensure that inclusive curricula are equitably distributed across districts. Three key themes were identified: LGBTQ+ underrepresentation in curricula, policies related to LGBTQ+ student protections, parental rights, and backlash bills, and disparities in student health outcomes among LGBTQ+ students compared to their cisgender peers. The paper then explores how state-level practices can be aligned with research and discusses the implications for future research and transformed practice
Listening Between the Lines: Dialogic Listening in Transracial Adoptive Families
No full textThesis (Master's)--University of Washington, 2025This article asserts that dialogic listening is an effective skill for the co-creation of understanding and connection within transracial adoptive family units. I analyze and explore this listening style within the parameters of a case study. This case study dissects a conversation observed between a twenty-six-year-old black man and his eighty-one-year-old adoptive white father regarding topics surrounding identity and racial negotiation. The dialogue from this interaction creates the perfect opportunity to explore how the concept of Dialogic listening is essential in listening through difference. Dialogic listening calls for open-mindedness and mutual respect. It also emphasizes deep engagement where all parties not only work to understand the context, but the emotions and experiences behind those contexts. Many adoptive families face unique communication challenges such as cultural, racial, and intergenerational differences can be amplified as the children begin to question what it means to discover their identities outside of their adoptive family unit. In many of these situations the adoptive parents and children, especially around social issues and identity, encounter exchanges that are complex and emotionally charged. Dialogic listening allows the family members to move from basic level understanding to engaging with the deeper narratives that shape their views
Incremental Cost of Hepatitis C Screening, Diagnosis and Treatment among People Who Inject Drugs in Kenya
Get PDFThesis (Master's)--University of Washington, 2025Hepatitis C virus infection is a global public health threat, and has potential to progress to chronic liver disease, liver cancer and preventable deaths, if left untreated. Among people who use injecting drugs, the prevalence of HCV is 52% globally and 13-40% in Kenya, which is higher than in the general population, where the prevalence is 0.7% globally and 0.9% in Kenya. Injectable drug use accounts for 1 in 3 HCV related deaths globally. While Direct Acting Antiviral treatment has been known to eradicate the virus by 95%,15 only 23% people were diagnosed with the virus and 5% initiated treatment globally, by 2020. In Africa, of 10% diagnosed with the virus, 0.4% initiated treatment. In Kenya, there is limited data of the proportion of people diagnosed with the virus and initiated on treatment. Additionally, there is a dearth of cost data for screening, diagnosis and treatment among people who inject drugs in Kenya. This was the first cost study with the largest cohort of people who inject drugs treated in Kenya. The two aims of the study were: 1. To estimate the annual incremental costs, using a micro-costing approach and payer (Ministry of Health) perspective over 5-year time horizon and 2. To determine human and other resources use by analyzing monitoring and evaluation data from time and motion surveys and health care provider interviews. The study analyzed secondary data collected from 123 clients who underwent screening, diagnosis and treatment in 8 needle syringe program and methadone treatment centers in Kenya. The total annual incremental costs were 398 and the biggest cost drivers were personnel, 83 (21%). The overall time taken for screening, diagnosis and treatment was 55 min (IQR 40, 103), out of which screening took the longest time, 20 min (18, 42). With an understanding of these costs, there is need for scale up these services to increase access to this priority population. Provision of treatment by the Ministry of Health and focus on this population, provides a valuable opportunity for Hepatitis C virus micro-elimination
Protein Design at Library Scale
Get PDFThesis (Ph.D.)--University of Washington, 2025Recent advances in de novo protein design have made it increasingly feasibleto create proteins with novel functions, driven by rapid progress in both com-
putational modeling and high-throughput experimentation. Modern tools can
explore vast sequence-structure spaces and evaluate biomolecular interactions,
while experimental assays can now screen billions of variants in parallel. Yet, a
key limitation remains: our current predictive models still struggle to capture the
complex physical and dynamical factors that underlie enzyme function. My the-
sis addresses this gap by developing an integrated experimental–computational
framework for enzyme design that couples large-scale protein library construc-
tion with data-driven model development. I design and test extensive libraries
of enzyme variants to both optimize catalytic activity and generate training data
for next-generation predictors of protein function. Ultimately, this approach ad-
vances our ability to connect sequence, structure, and function
Analysis of the Mechanically Choked Ram Accelerator
No full textThesis (Master's)--University of Washington, 2025The ram accelerator is a hypervelocity launch concept which uses a ramjet-like propulsive cycle to accelerate a projectile to hypersonic velocities. Research surrounding this technology has thus far been primarily focused on the thermally choked mode of operation, which relies on acceleration to sonic conditions of subsonic flow after the diffuser via constant area heat addition in order to bind the end of the combustion zone. However, early work suggested the possibility of using a nozzle to mechanically choke the flow, allowing the flow to be accelerated to greater than Mach one at the exit. Numerical work done with this mode demonstrated a substantial increases in thrust, sometimes double the non-dimensional thrust produced by the thermally choked mode at the same non-dimensional heat release value. Additionally, due to the mode’s ability to have the flow exit supersonically, the mode’s flight Mach number was shown to be able to exceed the Chapman-Jouguet detonation velocity, expanding the operable Mach number range. In order to validate these claims, a set of projectiles was manufactured and fired in the University of Washington’s ram accelerator laboratory. Over the course of these experiments the projectile showed a consistent and meaningful increase in both thrust and acceleration as compared to their thermally choked counterparts by an average of 50.1% and 20.5% respectively. This was in spite of increased mass accrued from the tail sections. The mode showed difficulty in starting in the first baffled tube when entering below 900 ms and showed consistent structuralfailure between 1150 - 1200 ms . Due to system limitations, these results were only shown through the baffled tube section of the system, and railed tube operation, which would be needed to fully validate theoretical claims, was unable to be successfully achieved. Regardless, the test series showed promising results and further testing will be required to validate the mode’s effectiveness as compared to theory
Psychosocial Support Needs and Preferences Among Family Caregivers of ICU Patients with Severe Acute Brain Injury: A Qualitative Thematic Analysis
No full textThesis (Master's)--University of Washington, 2025Family caregivers of patients with severe acute brain injury (SABI) are at risk for clinically significant chronic emotional distress, including depression, anxiety, and posttraumatic stress. Existing psychosocial interventions for caregivers of intensive care unit (ICU) patients are not tailored to the unique needs of caregivers of patients with SABI, do not demonstrate long-term efficacy, and may increase caregiver burden. In this study, we explored the needs and preferences for psychosocial services among SABI caregivers to inform the development and adaptation of interventions to reduce their emotional distress, during and after their relative's ICU admission. In this multicenter, longitudinal, qualitative study, we conducted semi-structed interviews with SABI caregivers at two time points: during their relative's ICU admission (n=30) and 2-months later (n=20). We analyzed qualitative data using a hybrid of inductive and deductive analytic techniques. We recruited family caregivers of patients with SABI from 14 U.S. neuroscience ICUs. We conducted interviews over live video. Our convenience sample of SABI caregivers (n=30) was recruited through referral by medical teams and nursing staffs across participating neuroscience ICUs. Caregivers included spouses, children, parents, and siblings to patients with SABI. We identified themes and subthemes related to participants' preferences for 1) the content of psychosocial support services, and 2) the delivery and implementation of psychosocial support services. Findings revealed a significant unmet need for psychosocial support around the time of ICU discharge and 2 months later, including: information to understand their loved one's condition and guide difficult decision-making, education regarding how best to communicate with the patient's care team and other family members, and emotional and behavioral coping skills. Our findings provide specific recommendations to justify and inform the development and adaptation of psychosocial support services for SABI caregivers in the ICU and post-discharge