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Citizen science data reveals winter warming delays cherry bloom in the Pacific Northwest, USA
No full textWe monitored cherry bloom date on the University of Washington campus, Seattle, USA, in three flowering cherry species and cultivars to develop a predictive model for estimating bloom, and to quantify changes in bloom date in Somei-yoshino cherry (Prunus x yedoensis) between 1966 and 2024. We worked with citizen scientists to record bloom date, and for Prunus x yedoensis, bloom phases, using ArcGIS Field Maps between 2012 and 2024. We also examined newspaper archives to reconstruct the observed bloom date for Prunus x yedoensis prior to 2012. We used a published modeling framework to develop species- and cultivar-specific models to predict bloom. We observed different thresholds for chill and heat requirements across flowering cherry species and cultivars, and general congruence between observed and model-predicted bloom dates for each. Using the longer time series in Prunus x yedoensis, we observed that warmer winters slowed the accumulation of required chill units, while warmer springs led to required heat units accruing more rapidly. The net effect of warming winters and springs resulted in a delay in the bloom date of Prunus x yedoensis by ~2 days per decade between 1966 and 2024. Shifts in the bloom date of flowering plants could result in phenological asynchrony with pollinators, with cascading effects across ecosystems. Further research is needed to understand the complex responses of flowering plants to shifting climatic conditions
Mental Health in the Modern Workplace: An Exploration of Individual and Relational Consequences of Employee Depression
No full textThesis (Ph.D.)--University of Washington, 2025Employee mental health is an increasing topic of conversation and concern in today’s workplace. This dissertation consists of two chapters that explore employee mental health, specifically depression, as an important determinant of both individual and relational workplace consequences. In the first chapter, I seek to understand how remote work uniquely impacts employees who are experiencing depression. Results from three studies, using both archival and online panel data, found that remote work does not uniquely hinder a depressed employee’s interpersonal well-being, but had inconsistent detrimental impacts to their intrapersonal well-being. In the second chapter, I seek to understand how the coworker of a depressed employee is perceived by another coworker when they attempt to engage in—and involve others in—social support behaviors. Across three experiments using both online panel and field data sources, results highlighted the critical role of depression stigma in determining the extent to which social support behaviors are evaluated as empathetic and appropriate. This dissertation extends an understanding of the ways in which depression as a mental health condition is consequential to both the employee experiencing the condition, as well as their coworkers and surrounding climate
The Interplay of Dataset Characteristics in Automated Grammar Generation: A Study with the AGGREGATION System
No full textThesis (Master's)--University of Washington, 2025In this thesis, I investigate how linguists can effectively prepare Interlinear Glossed Text (IGT) data for use with the AGGREGATION grammar inference system, particularly under constraints such as limited time, sparse annotations, and variable corpus quality. AGGREGATION aims to automate the creation of precision Head-driven Phrase Structure Grammar (HPSG) grammars from IGT, but its output quality depends heavily on input structure and annotation consistency. To explore this, I develop a modeling framework to evaluate how structural and annotation-based features (such as affix ambiguity, type-stems ratio, and POS tag source) affect grammar quality across 75,000 grammar runs on 25 datasets. I use both linear mixed-effects models and XGBoost to identify predictors of four key metrics: coverage, ambiguity, morphological complexity, and inference time. Results show that smaller, structurally coherent datasets often outperform larger, noisier ones. Manual POS tags improve coverage and generalization but increase ambiguity, while automatic tags result in cleaner grammars with lower parse success. A case study on Meitei highlights how annotation quality interacts with language-specific features. This work offers practical guidance for preparing IGT data for grammar generation and proposes future improvements to AGGREGATION, including support for structure-aware sampling and multi-version grammar comparison
A Comparative Study of Brain Structural and Functional Connectivity: Graph Topology, Individual Fingerprinting, and Predictive Modeling
No full textThesis (Master's)--University of Washington, 2025Brain connectivity analyses using neuroimaging data provide insights into the structural and functional organization of the human brain. Several approaches have thus been proposed for modeling structural and functional connectivity, each with its own strengths and limitations. This thesis compares functional connectivity (FC) estimates derived based on correlation and partial correlation, evaluating their graph topology and performance in individual identification and prediction tasks, while also contrasting them with structural connectivity (SC) networks. We begin by estimating FC networks based on marginal and partial correlation and further explore low-order partial correlation graphs as an intermediate approach. Motivated by studies suggesting that brain structural hubs are closely related to functional activity, we also propose an alternative FC construction method by regressing out the temporal activity of SC hubs. Our analysis shows that SC emphasizes within-hemisphere connections and exhibits small-world properties, while FC consistently reveals strong interhemispheric connections, regardless of the methodology. However, other network properties vary depending on the estimation method used. Finally, we assess these networks’ abilities to capture individual-specific features through subject identification and behavioral prediction tasks. We observe that partial correlation-based FC network performs well in subject identification when the sample size is large, but its performance deteriorates sharply with smaller samples. Additionally, regardless of estimation method, FC networks consistently outperform SC in predicting behavioral variables, and combining both typically improves predictive accuracy, except for partial correlation-based FC. Sample size and number of scan sessions used in FC estimation also have a non-trivial impact on predictive performance. Our study highlights the methodological implications of FC estimation strategies for brain network analysis
Heatwaves and Herbicides: Exploring the Relationship Between Temperature and Glyphosate Exposure
No full textThesis (Master's)--University of Washington, 2025Among the implications of climate change, higher temperatures may increase exposure to and absorption of hydrophilic substances like glyphosate, a widely used herbicide in the U.S. and worldwide. This study aims to explore spatial co-exposures of heat and glyphosate across the United States using descriptive and interactive mapping, characterization of wet bulb globe temperatures in the United States, and with nationally representative data from NHANES. This innovative research contributes to a deeper understanding of the complex interplay between warming ambient temperatures and environmental health hazards, emphasizing the necessity of addressing these interconnected challenges in the context of a warming climate
Transsexual as Posthuman: Approaching Trans Studies’ “Narrative Problem” through Trans and Posthumanist Genres
No full textThesis (Master's)--University of Washington, 2025“Transsexual as Posthuman” uses critical and narrative frameworks for trans studies and trans narratives as critiqued in Andrea Long Chu and Emmett Harsin Drager’s 2019 article “After Trans Studies.” With a focus on the role of the transsexual figure in postmodernity—and the haunting of Sandy Stone’s neologism “posttranssexual” therein—I analyze how satire, genre blending, dystopia, and the tagline “writing optimism without hope” may drive trans narratives present and future. I also argue that these tactics intertwine not only with trans, but with decolonial and extinction narratives as well. With persistent reference back to my own MFA creative thesis project, Inside Waters: Killer Whale Stories, I also analyze these tactics in Emily Zhou’s “Gen Z trans” realistic fiction short story collection Girlfriends (2023) and Lousie Erdrich’s Indigenous feminist dystopia Future Home of the Living God (2017)
Online Communities’ Sensitivity to Unexpected Information: The Roles of Governance and "Cross-talk"
No full textThesis (Master's)--University of Washington, 2025To stay on-topic, online communities exclude unexpected information, i.e., content they have no prior knowledge of, whose on-topicness is uncertain. However, unexpected information is valuable because it can enhance community members’ understanding of the information and drive online communities to explore novel topics that enrich their discussions. Of course, online communities vary in their sensitivity to unexpected information. Utilizing a dataset comprising discussions in 3,238 active communities on Reddit, this study investigates the effects of online communities’ formal and informal structures on communities’ sensitivity to unexpected information. The results indicate a negative association between formal structures represented by community governance and sensitivity to unexpected information, while showing a generally positive relationship between informal structures represented by "cross-talk" (i.e., conversations within a discussion that exclude the initiator of the discussion) and sensitivity. The findings uncover how cross-talk and community governance correlate with online communities' sensitivity to unexpected information, illuminating the effects of the informal and formal structures of online communities
GraphQL vs. REST: Performance and Scalability Analysis for Serverless Applications
No full textThesis (Master's)--University of Washington, 2025This thesis presents a comprehensive performance, scalability, and cost comparison of GraphQL and Representational State Transfer (REST) APIs within the context of serverless computing. While REST is the conventional choice for API implementation, its architectural style which is designed for network-based applications, specifically client-server applications, can lead to inefficiencies, such as over-fetching and under-fetching, leading to potential performance and price penalties in pay-per-use serverless environments. This work investigates GraphQL as a flexible and efficient interface alternative for two distinct and representative serverless application use cases: a CPU-bound image processing pipeline and a data-intensive relational database application.For the CPU-bound pipeline, experimental results demonstrate that GraphQL reduces client-perceived Round Trip Time (RTT) by eliminating network latency associated with multiple client-to-server round trips required to orchestrate the workflow with REST. For the data-intensive workload, GraphQL implementations show content-dependent performance compared to REST, with Apollo demonstrating 25-67\% performance improvements over REST on most operations, but worse scalability than REST under very high workloads.
Collectively, these findings illustrate that GraphQL provides advantages for serverless applications. The nature of these advantages is context-dependent, from orchestrating tasks in multi-step CPU-bound workflows to data-fetching from a relational database, establishing GraphQL as a compelling architectural alternative for modern cloud-native applications
Practical Second Harmonic Nonlinear Electrochemical Impedance Spectroscopy for Lithium-Ion Batteries
No full textThesis (Ph.D.)--University of Washington, 2025Lithium-ion batteries (LIBs) are intrinsically nonlinear electrochemical devices with two highly reactive electrodes separated by microns. Understanding the complex chemical and physical interaction between, and within, electrodes of practical LIBs requires in-situ and non-destructive characterizations to advance the field. Electrochemical impedance spectroscopy (EIS) is widely used for this purpose, but the method relies on linear approximations of nonlinear processes, leading to loss of information and model degeneracy. Second harmonic nonlinear electrochemical impedance spectroscopy (2nd-NLEIS), when measured simultaneously with EIS, is shown to address the challenges of model degeneracy and loss of information found in EIS. In this work, we provide a practical pathway for characterizing LIBs using 2nd-NLEIS, from simplified physics-based models and experimental data validation methods to quantitative 2nd-NLEIS analysis strategies and open-source software tools. Simplified physics-based models for 2nd-NLEIS consider the nonlinear contribution from Butler-Volmer kinetics and Warburg-like solid-state transport and thermodynamics. Analytical theories for 2nd-NLEIS in planar (Randles circuit) and macro-homogeneous porous electrodes are examined to fill the gap between complex full-physics modeling and the needs for practical physical parameter extraction from experimental data. For experiments involving aged LiBs, transmission line models (TLMs) extended to include the second harmonic response provide the flexibility needed to describe complex core-shell particles in the aged cells. Extended TLMs capture the evolution of EIS and 2nd-NLEIS spectra as commercial NMC|C cells age.
We show that 2nd-NLEIS spectra comply with Kramers–Kronig (KK) relations, enabling data quality tests that evaluate the stationarity and causality of EIS, and through this work, 2nd-NLEIS experiments. A nonlinear measurement model (MM) test coupled with measured total harmonic distortion (THD) of less than 1% is shown to be a foundation for ensuring data quality and a suitable perturbation amplitude required for simultaneous EIS and 2nd-NLEIS analysis. The practical implementation of these strategies is included in nleis.py, an open-source Python package, to ensure the reproducibility of the simultaneous EIS and 2nd-NLEIS analysis.
EIS and 2nd-NLEIS have complementary parity signals. In a full-cell measurement, the full-cell EIS signal is from the sum of the two half-cell signals whereas full-cell 2nd-NLEIS signals arise from the difference between the two half-cell signals. The summative EIS signals are denoted positive parity whereas the subtractive nature of 2nd-NLEIS is denoted negative parity, and when fit simultaneously to a common physics-based model, enable the first definitive impedance-based quantification of the evolving charge transfer symmetry for the NMC cathode during aging. Combining differential voltage analysis with simultaneous EIS and 2nd-NLEIS analysis, we have successfully quantified the growth of asymmetric charge transfer, especially at low states of charge (SOC). By varying SOC, it was observed that the cathode approaches symmetric charge transfer at intermediate SOC (50% SOC). This phenomenon perfectly aligns with the direction of lattice strain reduction given the formation of Ni-rich rocksalt surface layers on NMC particles, providing a non-invasive probe to the surface reconstruction of NMC cathode.
The last piece of this thesis focuses on the real-world impact of the advancements in 2nd-NLEIS. The importance of considering asymmetric charge transfer in time domain application (i.e., SOC estimation) was demonstrated using the full physics pseudo-two-dimensional (P2D) model. We also generated 10228 pairs of unique EIS and 2nd-NLEIS spectra using the full-physics P2D model to support data science assisted parameter estimation and the determination of the domain of applicability for simplified models in the future
Growth of Reciprocal pseudo-Anosovs on Lattice Surfaces
No full textThesis (Ph.D.)--University of Washington, 2025Motivated by number theory, Reciprocal geodesics were first introduced by Sarnak [23], who studied theirasymptotic growth on the modular curve. Erlandsson-Souto [7] gave a geometric interpretation and gener-
alization of reciprocal geodesics and a dynamical proof of asymptotic counting results in the more general
setting of hyperbolic orbifolds H2/Γ where Γ is a lattice. We introduce the notion of reciprocal pseudo-Anosov
maps of translation surfaces and establish a correspondence between such maps and reciprocal geodesics.
We then show how to apply the Erlandsson-Souto results to compute the asymptotic growth for particular
families of highly symmetric surfaces known as lattice surfaces or Veech surfaces [26], and to in fact compute
the constants for the asymptotic growth of pseudo-Anosov maps on certain families of lattices surfaces, called
Bouw-M¨oller [5] and primitive square-tiled surfaces [24