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Retention, mental health, and scalable treatment programs for youth living with HIV: An exploration of social and behavioral influences
No full textThesis (Ph.D.)--University of Washington, 2025Background: Adolescents and young adults living with HIV (AYLHIV) are at higher risk of negative health outcomes including disengagement from care, viral non-suppression, depression, and anxiety. This additional risk may be partially explained by the substantial changes in relationship structures, cognitive functioning, and independent self-management of HIV that occur throughout adolescence, but age-specific data is scarce. Understanding the demographic, social, and behavioral correlates of poor AYLHIV outcomes can inform tailored prevention programs and identify AYLHIV who could most benefit from interventions. As we seek to scale up evidence-based interventions to support youth engagement in care, stakeholder perspectives and priorities are necessary to identify implementation strategies with the highest likelihood of success.Methods: Chapters 1 and 2 of this dissertation used longitudinal survey data from the Data-informed Stepped Care study (DiSC; NCT05007717; MPIs: Drs. John-Stewart, Kohler, Agot). This cluster randomized clinical trial enrolled a cohort of 1,904 AYLHIV to evaluate the impact of a data-driven tool (the DiSC intervention) that tailored AYLHIV health services to youth needs. Chapter 1 aimed to identify demographic, social, behavioral, and care-related correlates of non-retention (missed visits and loss-to-follow-up [LTFU]) among AYLHIV while Chapter 2 assessed prevalence, longitudinal patterns, and correlates of depression and anxiety among AYLHIV using generalized mixed effects Poisson regressions. In Chapter 3, we conducted a workshop using the Nominal Group Technique (NGT) to guide a stakeholder workshop to prioritize implementation strategies to support scale-up and sustainability of the DiSC intervention.
Results: In Chapter 1, higher resilience and satisfaction with clinic were associated with lower risk of missed visits. Among males, satisfaction with clinic was associated with lower risk of missed visits while higher stigma was associated with increased risk. Among females, resilience was associated with lower risk. Having no living parents was associated with higher LTFU risk. In Chapter 2, prevalence of at least mild depressive and anxiety symptoms were 8.3% and 3.7% respectively, with significant declines over follow-up (p<0.001). Older age was associated with depression and anxiety. Previous experience of violence was associated with depression and anxiety across subgroups. Stigma was associated with higher prevalence of depression and anxiety, and associations varied by age and gender subgroup and stigma constructs. Personal experiences of stigma and perceived public stigma were most strongly associated with depression. Correlates of anxiety were similar to depression with differences in subgroups of age, gender, and mode of HIV acquisition. In Chapter 3, highly prioritized strategies included prioritization of AYLHIV with mental health and viral suppression challenges, improving provider training and resources, and continuous quality improvement meetings throughout stepped care scale-up. The majority of participants (82.5%) felt that appropriate strategies were identified. Workshop modifications (two-day format, implementation science education) were viewed particularly favorably in qualitative evaluations.
Conclusions: Older AYLHIV had the most retention and mental health challenges. Correlates of non-retention, depression, and anxiety vary substantially between strata of gender, age, and mode of HIV acquisition, highlighting the need for tailored strategies to address retention and mental health disorders among AYLHIV. Interventions targeting resilience-building, stigma reduction, and increasing satisfaction with care may be beneficial to improve outcomes for AYLHIV. Workshop stakeholders also identified a set of 10 implementation strategies that may improve uptake and use of the DiSC intervention among AYLHIV care and treatment implementers across Kenya. Future work is needed to evaluate strategy implementation and effectiveness and may consider incorporation of tailored interventions identified above
Impacts of giant cloud condensation nuclei on precipitation formation in marine low clouds
No full textThesis (Master's)--University of Washington, 2025Precipitation in low clouds strongly affects cloud responses to aerosol perturbations, thereby impacting aerosol radiative forcing of climate, a significant but indeterminate contribution to uncertainty in future warming. The onset of drizzle formation in marine low clouds may be influenced by the presence of coarse-mode sea salt aerosols with dry diameters exceeding 1 um. These particles can, under some circumstances, act as giant cloud condensation nuclei (GCCN) that benefit from rapid condensational growth to a size that initiates collision-coalescence. Aircraft-based in-situ observations of cloud microphysical properties and aerosol size distributions from the Aerosol-Cloud-Meteorology Interactions Over the Western Atlantic Experiment (ACTIVATE) are analyzed from January to June 2022. ACTIVATE focused on making detailed in situ microphysical measurements of aerosols and clouds using a low-flying research aircraft. The western Atlantic region is ideal for this study due to its location in the midlatitudes, where diverse cloud types can be observed under varying meteorological conditions. Unlike many aerosol-cloud interaction studies focused on subtropical regions, ACTIVATE’s emphasis on the midlatitudes provides a unique opportunity to examine aerosol impacts on precipitation formation in an area characterized by complex cloud structures and dynamic atmospheric processes. Observations from a cloud aerosol spectrometer (CAS) and a cloud droplet probe (CDP) in clear air from just below the cloud base are used to quantify size distributions of haze droplets. Clear-sky conditions for accurate interpretation of the size distributions are identified by strictly filtering for liquid water content below 0.0025 g/m³ to remove contamination from cloud droplets and total precipitation number concentration below 100 particles per cubic meter (#/m³), as measured by a two-dimensional stereo probe. These thresholds ensure that the size distributions measure haze droplets without cloud or drizzle droplet contamination. Haze droplet size distributions reveal modest correlations with near surface-level wind speeds when averaged together into wind speed bins, a result consistent with other recent studies. This is seen by a strong correlation coefficient between wind speed and total concentration of R =0.90 for the CAS and R =0.84 for the CDP. And consequently, I conclude, as near surface wind speed increases, the production of giant cloud condensation nuclei increases.
Observed GCCN distributions and cloud thicknesses are used to drive simulations with an explicit microphysics parcel model, exploring the conditions under which the observed range of GCCN induces a first-order impact on precipitation rates. Analysis of droplet size distributions using a 1-dimensional kinematic super-droplet cloud model (PySDM) demonstrates that even the addition of a small number of GCCN accelerates the onset of drizzle and increases drizzle rate in the marine boundary layer. This effect was analyzed under conditions with liquid water paths similar to those in the thicker parts of low cloud fields over the Western Atlantic region. Similarly, analysis with observationally derived rainwater content as a function of total concentration and liquid water content for high and low GCCN concentrations reveals an increased ratio of condensate in precipitation drops to that in cloud drops for flights with higher measured concentrations of GCCN. These results suggest that GCCN can meaningfully influence precipitation in marine low clouds
Towards a conceptual model for the management and conservation of Dungeness crab in the South Puget Sound
No full textThesis (Master's)--University of Washington, 2025Despite continued fishery closures as of 2018, significant declines in the abundance of Dungeness crab have been documented within the South Basin of Puget Sound, prompting an urgent need to understand the vulnerability of Dungeness crab to climate change and anthropogenic effects within the inland waters of the Salish Sea. An expert focus group and regional literature review were used to identify direct and indirect stressors on the Dungeness crab population in South Puget Sound. In this severely data-limited system, expert knowledge is used to provide the best available science to address critical resource management decisions. The goal of this project was the co-production of a conceptual model of the drivers of Dungeness crab abundance in South Puget Sound to inform research and management priorities, identify local knowledge gaps, and support future qualitative modeling efforts. Based on the results of the literature review and expert focus group discussions, the main drivers of Dungeness crab abundance appear to be the overlapping effects of climate change and eutrophication on dissolved oxygen, water temperature, and ocean acidification
Pediatric Dentist Experiences with Caregiver Radiograph and Imaging Refusal
No full textThesis (Master's)--University of Washington, 2025Purpose: This study investigated pediatric dentists’ experiences with caregiver radiograph and imaging refusal and how dentists manage it in clinic. Methods: American Academy of Pediatric Dentistry (AAPD) members were recruited by email from October 2024 to November 2024 to complete an online Research Electronic Data Capture (REDCap) survey on experiences with caregivers who refuse radiographs (intraoral, extraoral, and bitewing) and cone beam computed tomography (CBCT) imaging; bitewing radiograph refusal management; lead shielding practices; and provider and practice characteristics. Bivariate analyses were completed using the Chi-square test to identify practice-level characteristics associated with refusal (α=0.05). Results: Of the 8,342 invited participants, 695 completed the survey (8.3%). Substantial percentages of responding pediatric dentists reported radiograph and CBCT refusal to be a big or medium-sized problem (intraoral=23.2%; extraoral=12.1%; bitewing=21.7%; CBCT=9.0%). Pediatric dentists in private practice were significantly more likely to report radiograph refusal as a big problem than those in community health center/public health clinic or hospital/university settings (P-values50% Medicaid-enrolled children reported having significantly fewer caregivers who refused radiographs (P-values<.05); there was no difference in CBCT refusal by % Medicaid (P=.42). Dentists believed caregivers who refused immunizations and those who refused fluoride were most likely to refuse bitewing radiographs. Most dentists (81.0%) used lead shielding, for whom the most common reason was that it increased caregiver acceptance of radiographs (73.6%). Conclusions: Radiograph and CBCT imaging refusal are significant clinical challenges, which highlights the importance of developing chairside strategies that pediatric dentists can use to help caregivers make decisions about radiographs and imaging for their children
Can Sidewalk and Crosswalk Availability Strengthen Association Between Physical Activity and National Walkability Index
No full textThesis (Master's)--University of Washington, 2025The majority of U.S. adults do not meet the recommended amount of weekly physical activity. Urban design researchers have studied micro and macro scale features to understand if physical activity, mainly walking, can be bolstered with different initiatives. These studies have resulted in mixed findings. We used a large cross-sectional sample spanning the U.S. from the INSPACE collaborative to quantify the association between neighborhood context, as measured by sidewalk availability, crosswalk availability, and the National Walkability Index, and accelerometer measured physical activity. We set thresholds for moderate to vigorous physical activity and averaged them by day to generate the outcome measure. We estimated the association between context and activity using linear regression to adjust for individual-level age and sex and neighborhood-level income. When using a threshold dependent on age, location of device, and type of device, we found that on average an increase in sidewalk availability by 10% increased mean MVPA per day by approximately 0.63 minutes (95% robust CI: 0.06-1.2). The significance of this relationship held when adjusting for the National Walkability Index. However, when we performed a sensitivity analysis with an age-agnostic threshold, the association between neighborhood context and physical activity weakened whereas the age parameter strongly predicted physical activity. We uncovered an association between sidewalk availability and physical activity; however this could be an artifact of our age-dependent threshold defining moderate to vigorous physical activity per day. Nonetheless, our findings suggest further research on micro scale features may better illuminate determinants of neighborhood walking
Healthcare Utilization and Cost Burden Associated with Depression among Patients with Alzheimer’s Disease - A Retrospective Cohort Analysis
No full textThesis (Master's)--University of Washington, 2025Background: Alzheimer’s disease (AD) is the most common cause of dementia in the United States. Patients with AD have increased use of healthcare services, including more frequent high-cost events like hospitalizations and emergency department (ED) visits, compared to cognitively normal individuals. Neuropsychiatric symptoms are more common in individuals with AD than in the general population. Many patients exhibit symptoms consistent with depression, such as mood changes, social withdrawal, apathy, and suicidal ideation. Additionally, individuals with AD and comorbid depression tend to show more severe neuropathological changes, including greater accumulation of tau, amyloid, and vascular pathology, compared to those without depression. Depression and its related symptoms in AD patients contribute to greater caregiver burden, higher fall risk, and a greater likelihood of requiring costly interventions such as skilled nursing care and early institutionalization. To our knowledge, no studies have looked at the associated healthcare burden of comorbid depression among patients with AD. Objective: In this study, we compared AD patients with depression to AD patients without depression with respect to patient characteristics, healthcare resource utilization, and costs to characterize the healthcare burden.
Methods: We performed a retrospective cohort study using MarketScan® health insurance claims data. AD patients with depression within three years of AD diagnosis and AD patients without depression were identified between January 1st, 2017, and December 31st, 2022, and followed for up to one year after their depression or proxy diagnosis. AD controls were matched 6:1 to AD with depression cases. The primary outcomes of interest were all-cause healthcare resource utilization and expenditures during the follow-up period.
Results: In the 12-month follow-up, patients with AD and comorbid depression had substantially higher healthcare costs and utilization compared to those without depression. Adjusted models showed significantly higher total costs (+11,623, $14,554) and greater utilization, including more ED visits, office visits, drug claims, inpatient days, and hospital admissions, all of which were statistically significant.
Conclusion: The results of this study suggest that the financial burden following depression diagnosis in AD patients is substantial. These findings highlight the need for more effective treatments that can mitigate the resource use and economic burden in the management of depression among this vulnerable population. There is a clear unmet need for properly managing depression in patients with underlying AD
Associations of Serum Neurofilament Light Chain Concentration with Able Life and Healthy Life in Older Adults: The Cardiovascular Health Study
No full textThesis (Master's)--University of Washington, 2025Serum neurofilament light chain (NfL) is a sensitive biomarker of brain injury, which has been increasingly used to prognosticate and monitor disease activity and treatment response in neurological diseases. Neural injury impacts the ability to live independently and maintain long-term health. These analyses aimed to examine the association of serum NfL concentrations with able life and healthy life among older adults. We used data from the Cardiovascular Health Study (CHS), a longitudinal cohort study of adults aged 65 and older. Eligible participants in our analyses were free of stroke or transient ischemic attack (TIA) and had serum NfL measured. Over 13 years of follow-up, outcomes were years of life (YOL), years of able life (YAL), years of healthy life (YHL), YAL/YOL%, and YHL/YOL%. “Able” was defined by independence in activities of daily living (ADLs), and “healthy” was defined by self-reported health status. Associations of serum NfL with each outcome were assessed using linear regression and spline linear regression models. A total of 1,957 participants (mean age 77.8) were included. In the fully adjusted linear model, each doubling of NfL concentration was associated with 1.0 fewer YOL, 1.2 fewer YAL, 0.9 fewer YHL, 4.9% lower YAL/YOL% and 3.1% lower YHL/YOL%. Spline analysis showed the strongest associations at NfL concentration of 19.7–33.8 pg/mL (between the 25th-75th percentiles), where each doubling of NfL concentration was associated with 11.2% lower YAL/YOL% and 9.5% lower YHL/YOL%. Although women lived longer than men, they spent a smaller proportion of follow-up able and healthy. Serum NfL concentration might serve as a valuable predictor of able and healthy life among older adults free of stroke or TIA. The goal of incorporating this biomarker into routine examination would be to enable earlier interventions to preserve ADLs and extend both able and healthy life expectancy
The Role of Neighborhood Opportunity in Early Childhood Asthma and Differences by Urbanicity
No full textThesis (Master's)--University of Washington, 2025IntroductionAsthma is a prevalent chronic condition among children in the United States, with children in Washington state accounting for 20% of the state’s estimated 600,000 asthma cases. Neighborhood environments during the sensitive developmental period of infancy can influence respiratory health, yet their role in the etiology of childhood asthma remains underexplored. The Childhood Opportunity Index (COI) offers a comprehensive measure of neighborhood-level structural, environmental, and socioeconomic factors. This study examined associations between COI scores during infancy with early childhood (4-6 years) asthma and wheeze, and whether these associations varied by urbanicity.
Methods
We analyzed data from 457 children enrolled in the ECHO PATHWAYS-GAPPS cohort across two Washington state sites: Seattle and Yakima. Neighborhood opportunity was assessed using COI scores categorized into very low/low, moderate, and high/very high opportunity; sensitivity analyses used continuous scores scaled to the interquartile range (IQR). Asthma and wheeze outcomes were measured at the 4-6 year child visit via caregiver-reported validated questionnaires. Multivariable logistic regression estimated adjusted odds ratios (aORs) and 95% confidence intervals (CIs). Models were adjusted for child sex, maternal race/ethnicity, maternal education, maternal age at delivery, maternal history of asthma, study site, and household smoker. An interaction model tested for effect modification by urbanicity (recruitment site).
Results
Of the 457 participants, 207 caregivers were recruited from birthing centers at a hospital in Yakima and 250 from two Seattle hospitals. Most children (n=365; 79.9%) lived in neighborhoods classified as moderate and high/very high opportunity. Asthma and wheeze were reported in 11.5% and 12.6% of participants, respectively. No statistically significant associations were observed between overall COI and either outcome. Domain-specific analyses did not reveal strong associations, though estimates generally indicated increased odds of asthma and wheeze as neighborhood opportunity improved. No evidence of effect modification by urbanicity was found for asthma (p=0.519) and wheeze (p=0.802).
Conclusions
Neighborhood opportunity during infancy was not found to be associated with asthma or wheeze in early childhood (ages 4-6 years), and associations did not vary by urbanicity. Patterns of elevated odds in more opportune environments may reflect greater access to healthcare and caregiver engagement with diagnostic resources, rather than true differences in disease burden. Findings diverge from prior literature, highlighting the complexity of neighborhood influences on early respiratory health
Electrification of On-Demand Transportation: A Comparative Analysis of Individual Perceptions on the Electrification of Taxis and TNCs
No full textThesis (Master's)--University of Washington, 2025This thesis explores the divergent pathways of electric vehicle (EV) adoption within San Francisco’s on-demand transportation sector, focusing on taxis and Transportation Network Companies (TNCs) such as Uber and Lyft. As cities advance aggressive climate mandates, electrifying high-mileage urban fleets is both a technical opportunity and a policy challenge. Drawing on six semi-structured interviews with key stakeholders and a spatial analysis of EV charging infrastructure, this study examines how individual perceptions, regulatory structures, and institutional support influence electrification trajectories. Findings reveal that while TNCs have made significant progress, enabled by corporate incentives, flexible ownership models, and regulatory alignment, the taxi industry faces more acute barriers, including limited infrastructure access, financial constraints, and skepticism toward policy support. Thematic coding highlights contrasts in agency, awareness, and trust, with taxi stakeholders frequently citing fragmented communication and operational inflexibility as key deterrents. Spatial analysis further demonstrates infrastructural inequities that compound these challenges. This research contributes to a growing body of literature framing electrification not only as a technological transition but as a reflection of institutional capacity, governance design, and the perceived legitimacy of change. The thesis concludes with planning recommendations that emphasize differentiated policy tools, equity-centered infrastructure investment, and the need for more inclusive communication strategies to ensure a just and comprehensive transition to zero-emission on-demand mobility
Crural Indices in Neandertals and Modern Humans: Implications for Limb Proportions, Environment, and Body Size Variation
No full textThesis (Ph.D.)--University of Washington, 2025This dissertation investigates the functional and adaptive significance of Neandertal limb morphology by integrating comparative anatomy, biomechanical modeling, and methodological validation. The crural index (CI)— a ratio of tibial to femoral length— served as a key metric for exploring thermoregulatory and terrain-related adaptations.In Chapter 3, CI values were analyzed across 21 modern human populations and multiple Neandertal individuals. Neandertals exhibited lower average CIs than modern humans, consistent with cold-adapted body forms, but fell within the observed range of modern variation. Chapter 4 modeled center of mass (CoM) shifts on sloped terrain and found that Neandertal limb proportions and trunk morphology produced a lower and more posterior CoM than in modern humans. These differences became more pronounced on inclines, suggesting biomechanical advantages for locomotion in rugged environments. Chapter 5 validated the use of external anatomical landmarks to estimate skeletal limb lengths using CT data from over 100 individuals. While femoral and tibial lengths showed strong agreement between external and skeletal measurements (R² > 0.97), crural index values derived from external landmarks exhibited only moderate correlation (R² = 0.60), highlighting limitations in ratio-based proxies.
Together, these findings support a multifactorial model of Neandertal adaptation involving both climatic and biomechanical selective pressures. They also emphasize the importance of methodological rigor when using external measurements in evolutionary analyses. This work contributes a refined framework for interpreting postcranial morphology in both fossil and modern human populations