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Effect of Splice Length and Creep on the Structural Response of Reinforced Concrete Columns Subjected to Pure Compressive Loading
No full textThesis (Master's)--University of Washington, 2025On June 24, 2021, the Champlain Towers South (CTS) condominiums in Surfside, Florida partially collapsed. A forensic investigation was launched by the National Institute of Standards and Technology (NIST) to determine the technical cause of the collapse and to use this understanding to recommend changes to building codes, standards, and practices. NIST contracted a structural engineering team at the University of Washington (UW) to perform multiple components of an experimental research program. This thesis focuses on the portion of the testing program aimed at determining the effect that lap splices and long-term loading have on the axial compressive response of reinforced concrete columns.Three full-scale column specimens were designed to simulate the structural elements from the CTS building. The column specimens were constructed, instrumented, and tested in axial compression at the UW Structural Engineering Testing Laboratory. One of the column specimens was loaded for 120 days prior to destructive testing to simulate the load that the building underwent for 40 years before the collapse occurred. The research program was especially important due to the limited amount of research previously conducted on concentrically loaded reinforced concrete columns with compression lap splices. None of the previous research programs included column specimens with geometry similar to what was seen in the CTS building. 6x12 in. (152x305 mm) companion cylinders were also cast and tested under sustained loading to learn more about the performance of the concrete in the column specimens.
The results from the experimental tests were shared with NIST to aid in their forensic investigation. Some additional observations were made: (1) introducing a compression lap splice decreased the axial compressive strength of the reinforced concrete columns tested and (2) long-term loading did not decrease the axial compressive strength of the reinforced concrete columns tested. When comparing the experimental creep and shrinkage of the companion cylinders to the ACI 209.2R-08 creep and shrinkage prediction models, it was found that the prediction models generally underestimated the creep and shrinkage of unsealed companion cylinders. While this research program unveiled some information about the axial compressive performance of reinforced concrete columns with lap splices and long-term loading, further research is required to improve the design of compression lap splices in reinforced concrete columns
Continuous Exposures and Inverse Problems in Causal Inference
No full textThesis (Ph.D.)--University of Washington, 2025This dissertation studies challenges that arise in causal inference with continuous exposures, with particular emphasis on the role of ill-posed inverse problems. Common causal estimands in continuous exposure settings are often difficult to interpret, challenging to estimate, or rely on strong and potentially unrealistic identification assumptions. The first project introduces and studies a class of stochastic interventions for continuous exposures that yield scientifically interpretable causal estimands which can be identified from observed data without reliance on the positivity assumption. We establish conditions for identification and propose and study an influence function-based estimator. The estimator’s performance is examined in simulations for both uncensored and right-censored outcomes, and the method is applied to the study of correlates of protection in an HIV vaccine trial. The second project considers a two-sample instrumental variable framework for causal inference when the exposure is observed with error. The causal estimand is formulated as a functional of a solution of an ill-posed integral equation, thus connecting the problem to recent work on statistical inverse problems. An estimating equations-based estimator is proposed, its asymptotic properties are studied, and its finite-sample performance is evaluated through simulations. The method is applied to data from the COVAIL study. The third project scrutinizes common assumptions used in the analysis of statistical inverse problems, which can be difficult to interpret in causal inference settings. These assumptions are explored using tools from microlocal and harmonic analysis, providing further insight into these assumptions and suggesting avenues for future work
Interplay of Demographic Factors, Behavioral Factors, and Chronic Disease Status with Diabetes and Tooth Loss
No full textThesis (Master's)--University of Washington, 2025Tooth loss is associated with type 2 diabetes, but the extent to which demographic, behavioral, and health factors influence this association remains unclear. To evaluate this association, the 2022 Behavioral Risk Factor Surveillance System (BRFSS) data for 26,152 Washington State adults who provided information on variables of interest was analyzed. Participant characteristics were summarized by frequencies and percentages overall and stratified by tooth loss and diabetes status. Two models were fit to assess the association between self-reported diabetes (yes/no) and tooth loss (none, 1–5 teeth lost, ≥6 teeth lost); a crude model and a fully adjusted multinomial logistic regression model to assess the association controlling for age, sex, race/ethnicity, education, income, insurance status, marital status, county, smoking status, obesity, and cardiovascular disease. An exploratory analysis restricted to adults aged ≥45 years used the same modeling approach. All analyses were conducted in R. Among participants, 11.6% reported diabetes; 28.3% lost 1–5 teeth, 12.5% lost ≥ 6 teeth, and 59.2% reported no tooth loss. In adjusted multinomial model of 17, 373 adults, diabetes was an independent predictor of losing ≥6 teeth (adjusted OR = 1.79; 95 % CI, 1.35–2.37; p < 0.001). Older age, lower household income, lack of private health insurance, unemployment, current or former smoking, and cardiovascular disease were also significantly associated with severe tooth loss. Conclusion: Greater tooth loss was significantly associated with diabetes. This association was impacted by age, income, employment, smoking, and cardiovascular disease status
How the Few Control the Many: or How to Save Money and Find Happiness by Recognizing Subtle Social Manipulation and Rejecting It
Get PDFT SOC 165 Introduction to Sociology: Developing the Sociological ImaginationThis presentation provides a brief look into the sociological factors which drive consumerism beyond healthy levels. It utilizes a highly synthesized approach so as to provide only enough information to prompt the reader into critical thought about personal and societal relationships with capitalism and over-consumption in the modern era
Development of a High Throughput Methodology of a Mechanoredox Free Radical Polymerization Procedure
No full textThesis (Master's)--University of Washington, 2025High-throughput methodologies are widely applied in polymer research because they enable the efficient exploration of large and complex design spaces. These approaches allow researchers to rapidly test and evaluate diverse reaction conditions, formulations, and polymer architectures. However, many existing high-throughput strategies face notable limitations, including a high degree of specialization that restricts broader applicability, low polymer yield that constrains downstream characterization, and reliance on solution-based reactions that may not be suitable for all systems. Ball mill mechanoredox polymerization is a novel radical based polymerization pathway that produces large volumes of polymers and is virtually solvent free, allowing for the access of unique polymer architectures. This workflow offers a way of producing ball mill mechanoredox polymers in a high throughput capacity. This workflow utilized the Science Jubilee automation platform with custom reaction hardware to produce up to 64 formulations at a time. Results from a polymerization campaign show this methods accuracy, precision, and viability to synthesis polymers in a high throughput manner
The role of glia and CED-1/MEGF10 in C. elegans models of Parkinson's disease
Get PDFThesis (Ph.D.)--University of Washington, 2025Parkinson's disease (PD) is marked by progressive dopamine neuron degeneration, but the phagocytic receptors and cells that clear dopamine neuron corpses are unknown. Further, while other cell types like glia, skin, and muscle are also affected in PD, their role in disease progression is unclear. In my thesis project, I found that astrocyte-like CEPsh glia are neurotoxic in C. elegans PD models by regulating the neuronal dopamine biosynthesis enzyme CAT-2/tyrosine hydroxylase. I also identified epithelia and muscle as the phagocytes for dopamine neuron corpses. They engulf by recognizing phosphatidylserine on necrotic-like neuron corpses via the conserved receptor CED-1/Draper/MEGF10. Loss of ced-1 protects from loss of dopamine neurons but does not protect against the impairment of associated dopaminergic behaviors. Altogether, my thesis work provides evidence for the involvement of glia, muscle, and epithelial cells as potential mediators of dopamine neuron degeneration. Thus, my thesis work suggests that PD may be a disease of multi-organ dysfunction and could inform future therapeutic interventions
Associations of clinical features with kidney tubular biomarker trajectories in individuals with type 1 diabetes
Get PDFThesis (Master's)--University of Washington, 2025BackgroundIdentification of risk factors of tubular injury and dysfunction among individuals with type 1 diabetes (T1D) may provide insight into the mechanisms underlying tubulointerstitial pathology and allow for improved kidney health prognostication and treatment. MethodsWe examined associations of clinical characteristics and drug interventions on tubular biomarker trends in two T1D cohorts: (1) the Renin Angiotensin System Study (RASS, n=283) including adults with early T1D and no clinical evidence of kidney disease, randomized to enalapril, losartan, or placebo; and (2) the Preventing Early Renal Loss in Diabetes Study (PERL, n=530) including adults with longstanding T1D and chronic kidney disease (CKD) or at risk of kidney disease progression, randomized to allopurinol or placebo. Biomarkers were measured at 3 time points (baseline, mid-trial, closeout) over 5 years follow-up in RASS and 3 years follow-up in PERL. Measurements included: KIM-1, sTNFR1, arginine-citrulline ratio in plasma; EGF, UMOD in timed urine; a composite tubular secretion score reflecting clearances of 8 proximal tubular secreted solutes. ResultsAt baseline, RASS participants had a mean age of 30 years and 47% were male, with mean diabetes duration 11 years, hemoglobin A1c (HbA1c) 8.6%, iohexol-derived glomerular filtration rate (iGFR) 128 ml/min/1.73m2, and albumin excretion rate (AER) 6 ug/min. PERL participants had a mean age of 51 years and 66% were male, with mean diabetes duration 35 years, HbA1c 8.2%, iGFR 68 ml/min/1.73m2, and AER 286 ug/min. We observed significant changes in tubular biomarkers across both cohorts, suggesting progressive tubular injury and dysfunction. We identified baseline HbA1c and AER as factors associated with changes in multiple tubular biomarkers. Higher baseline HbA1c was associated with faster rise in KIM-1 (4.8 pg/mL increase per year, [95% CI 2.3, 7.3]), slower decline in arginine-citrulline ratio (0.02 unit slower decrease per year, [95% CI 0, 0.03]), and faster decline in EGF in RASS (194.7 ug/day decrease per year, [95% CI 6.8, 382.7]), and with faster rise in sTNFR1 in PERL (27.6 pg/mL increase per year, [95% CI 18.8, 36.5]). Higher baseline urinary albumin excretion rate was associated with faster declines in EGF (346.1 ug/day decrease per year, [95% CI 65.3, 626.8]) in RASS , and with faster rise in sTNFR1 (18.1 pg/mL increase per year, [95% CI 14.8, 21.4]) and faster declines in EGF (139.8 ug/day decrease per year [95% CI 31.9, 247.7]) and tubular secretion score (0.2 unit decrease per year, [95% CI 0.1, 0.3]) in PERL. Age, sex, and baseline age, diabetes duration, SBP, iGFR, and randomization to intervention versus placebo had limited associations with tubular biomarker trajectories. ConclusionLongitudinal changes in tubular biomarkers reflect progressive tubulointerstitial injury and dysfunction across the course of T1D DKD and are influenced by baseline glycemia and albuminuria
Surgical Scene Understanding Towards Human-Centered Collaboration in Robotic Surgery
No full textThesis (Ph.D.)--University of Washington, 2025Robot-assisted minimally invasive surgery brings together the expertise of highly-skilled surgeons with the increased precision and dexterity of assistive robots. Surgical robots currently in deployment provide surgeons with enhanced visualization, filter out hand tremors, and incorporate data integration and analytics to facilitate improved patient care. Mostsurgical robots, however, are still constrained to being teleoperated by a surgeon, with limited advances towards integrating automation in the operating room. The use of automation in surgery has the potential to extend the current benefits of robotic surgery to integrate more consistent care by reducing variability. While studies have explored automating tasks
performed by a surgeon, the role of the first assistant during surgeries has often been underappreciated in the context of automation. However, this role is pivotal in ensuring the smooth progression of procedures, maintaining a clear surgical field, and providing critical support to the primary surgeon. To this end, offloading some sub-tasks performed by the first assistant to automated systems can reduce the risk of human error and optimize re- source allocation. Building on the viability of camera sensors as a reliable input, the goal of this thesis was to aid the development of an autonomous suction assistance tool by developing the infrastructure for surgical scene understanding. This work developed surgical segmentation models for efficient segmentation of binary, parts and instrument segmentation, established approaches for addressing the paucity of labeled data in surgical settings, and developed a framework to benchmark approaches to cooperative autonomy through the lens of an assistive suction tas
Analysis of the Vertebral Morphology of Pacific Sand Lance, Ammodytes personatus
No full textPacific sand lance (Ammodytes personatus) are small head-first burrowing fish distributed throughout the North Pacific Ocean. Despite lacking typical morphology of other burrowers, their elongate bodies allow for rapid burrowing through undulation. Vertebrae support full-body movements like swimming and bear the mechanical load for the axial skeleton. We hypothesize that structural changes in vertebrae, such as changes in mineralization and shape, enhance undulatory performance and help generate the forces needed for burial. We microCT scanned 22 sand lance (SL 33-95mm) to estimate the bone mineral density and used geometric morphometrics to characterize shape variation along the length of the fish and over ontogeny. We found sand lance vertebrae were 1.25 times denser near the head and tail regions compared to the middle. Additionally, the main drivers of vertebral shape variation were the prominence of the hemal spine and the angle of the neural and hemal spines relative to the centrum. These localized morphological increases in density and shifts in spine orientation may serve as additional support and points of force transmission for initiating and sustaining burial
Effects of Histotripsy on Bacterial Viability in Suspension
No full textThesis (Ph.D.)--University of Washington, 2025This dissertation explores the bactericidal effects of histotripsy, a cavitation-based focused ultrasound therapy, on two bacteria in suspension namely Escherichia coli and Staphylococcus aureus, for potential application in abscess treatment. Abscesses are localized encapsulated collections of pus and bacteria that present a clinical challenge. Histotripsy can non-invasively reduce the bacterial burden in the abscess by rupturing bacterial cell walls via intense cavitation. To understand histotripsy process on bacteria in suspension, two regimens of histotripsy (shock-scattering histotripsy and boiling histotripsy) were applied in vitro on bacterial suspensions at frequencies ranging from 0.81 MHz to 3.25 MHz, at 1% duty cycle, and bacterial viability was quantified by the plate count assay. Cavitation was quantified by passive cavitation detection, plane-wave B-mode imaging and high-speed photography. Results showed that both regimens reduced E. coli counts significantly. Cavitation cloud size in shock-scattering histotripsy quantified by high-speed photography strongly predicted the E. coli inactivation. Subsequently, plane-wave B-mode imaging was applied to estimate cavitation cloud size enabling the prediction of E. coli inactivation rates in future clinical studies. On the other hand, Staphylococcus aureus was resistant to histotripsy treatment. Efforts were made to obtain bactericidal activity by de-clumping S. aureus clusters into individual cells, treating smaller volumes, and combining histotripsy with heating, with negligible response. Finally, an investigation was conducted to determine the effect of bacterial shape and gram status on their resistance to histotripsy treatment