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Drawing Democracies: Redistricting in America
No full textThis dissertation investigates the institutions which underly the drawing of districts in the United States. State, legislative, and local districts in the United States are redrawn following each decennial census. These districts define constituencies for the decade, which in turn define the partisan, racial, and ideological makeup of elected officials in legislatures and on councils across the country. Here, I present a series of studies which explore when and how institutions constrain and improve the redistricting process.
The first study replicates and extends the standard analyses analyzing the effectiveness of redistricting commissions. Redistricting commissions are the default reform to redistricting processes to limit the ability of partisans to influence districting plans. Here, I explain how most of these studies incorrectly analyze data on redistricting plans by treating districts within or across years as independent. As such, previous research has overstated the impact of enacting redistricting commissions.
The second study, which is coauthored with Cory McCartan, Tyler Simko, Shiro Kuriwaki, and Kosuke Imai, measures the degree of partisan gerrymandering in the 2020 cycle. We use a new dataset of redistricting simulations for all 50 states to establish district-level manipulations of redistricting outcomes. Primarily, we show that partisan gerrymandering is widespread, where plans have partisan biases in most states. Yet, Democrats and Republicans gerrymander at similar rates, which results in only a small national bias. Even so, gerrymandering reduces competition across the board, which in turn reduces the responsiveness of the House to changes in voter preferences.
The third study explores the relationship between map drawers, the courts which oversee them, and written redistricting rules. Many states have adopted explicit redistricting rules in the form of laws and constitutional amendments which guide and constrain the redistricting process. Due to recent changes in federal following Rucho v. Common Cause in 2019, state courts hold final control over most of these rules. I exploit differences in rules across states to demonstrate that map drawers typically follow written rules within each state. State courts are more likely to intervene when there are written rules, even for a fixed amount of bias in a plan. Finally, when state courts chose to intervene, they decreased the bias of adopted plans.
The fourth study, which is coauthored with Cory McCartan, Tyler Simko, Emma Ebowe, Michael Zhao, and Kosuke Imai, evaluates the causal effect of reducing the leeway that partisan actors have over the redistricting process. Here, we develop a formal model which maps onto the possible steps in any given redistricting process. We apply this model to 2010 and 2020 redistricting processes. The differences in equilibria across time become the treatment variable in a continuous differences-in-differences-in-differences model. We demonstrate that the bundles of reforms which decrease partisan leeway cause a decrease in partisan bias and an increase in political competitiveness. Further, through counterfactual policy analyses, we show that fully independent processes result in larger changes than more typical, constrained reforms.
The final study, coauthored with Cory McCartan, introduces a relative measure of electoral fairness which incorporates both counterfactuals and individual characteristics to solve the issues absolute measures face. Most work to evaluate redistricting plans has focused on absolute measures of partisan gerrymandering, such as the efficiency gap or partisan symmetry. Absolute measures are unable to account for legal criteria in map drawing and pre-existing political geography. Further, existing methods cannot separate partisan effects from racial effects, especially in places where race and party are highly correlated. We demonstrate that this relative approach to fairness captures standard partisan gerrymanders and can be applied to both racial and ideological gerrymandering.Governmen
Production of Ovarian Cell Types from Human Pluripotent Stem Cells
No full textThe ovary is the central organ of female reproduction, and understanding it is crucial for improving women’s health and treating infertility. However, studies of human ovarian development are limited by technical and ethical challenges in accessing ovarian tissue, especially during fetal stages. Therefore, engineering stem cell-based models of the human ovary in vitro has the potential to rapidly advance the study of human reproduction by enabling experiments that would not otherwise be possible. Furthermore, if the full process of human oogenesis can be re-created in vitro starting from pluripotent stem cells, this would be a transformative therapy for millions of people around the world who are infertile due to a lack of eggs. Although in vitro oogenesis has recently been achieved in mice, this has not yet been successful for humans, largely due to a lack of methods for producing the necessary ovarian cell types.
In this dissertation, I present my work on directing the differentiation of human induced pluripo- tent stem cells (hiPSCs) into ovarian cell types in vitro, including granulosa-like, oogonia-like, and mei- otic cells. My overall approach has centered on using computational tools and multiplexed screens to identify key regulatory factors that drive the formation of a cell type of interest. In Chapter 1, I discuss the production of granulosa-like cells and their application in forming ovarian organoids. In Chapter 2, I showcase a method for the rapid generation of oogonia-like cells with erasure of DNA methy- lation. In Chapter 3, I describe my latest work on directly initiating meiosis from hiPSCs. Overall, these methods establish in vitro models of various aspects of ovarian development that will be useful to researchers in the field, and may serve as the basis for future therapies such as in vitro oogenesis.Chemistry and Chemical Biolog
Inference of Intervention Impact and Epidemic Intensity for Infectious Diseases
No full textOutbreaks of SARS-CoV-2, HIV, and other infectious pathogens have a profound impact on public health globally. Public health surveillance, defined as “ongoing systematic collection, analysis, and interpretation of health data,” serves two primary purposes in informing public health decisions: Evaluating the impact of infectious disease interventions and estimating epidemic intensity.
In Chapter 2, we use surveillance data to estimate vaccine-preventable COVID-19-associated deaths among unvaccinated individuals in the United States. We estimated that hundreds of thousands of deaths could have been directly prevented through vaccination among unvaccinated adults during the 15-month study period. In Chapter 3, we examine the commonly held assumption that due to the indirect effects of vaccination in preventing transmissions, vaccination could have prevented more outcomes overall across the entire population than could have directly among unvaccinated individuals (or that vaccination has prevented more outcomes overall than it has directly among the vaccinated individuals). We demonstrate that the direct impact of vaccination among vaccinated (or unvaccinated) individuals is a lower bound on overall impact across all individuals when indirect effects are non-negative. Using simulations, we illustrate how this lower bound may fail under common vio¬lations to assumptions on time-invariant vaccine efficacy, pathogen properties, or behavioral parameters.
In Chapter 4, we explore key considerations when using routinely collected data on HIV diagnosis and status ascertainment among pregnant women attending antenatal care (ANC) as a sentinel population to monitor HIV incidence trends in the population at large in generalized HIV epidemic settings. However, ancillary factors—such as those related to fertility, non-disclosure of status awareness, and testing patterns outside of ANC—may also influence trends in ANC surveillance measures, even though incidence remain unchanged. Using simulations and data from a recent study as an example, we demonstrated that trends in ANC surveillance measures may be explained by changes in these ancillary factors, leading to biased incidence estimates if unaccounted. Our findings highlight the importance of accounting for these ancillary factors when interpreting trends in the ANC measures to infer incidence trends. In addition, we show that when incidence is low, a modest, unaccounted change in non-disclosure proportion produce trends in the new diagnoses rate similar to those caused by a large decrease in incidence. Therefore, true new diagnoses should be distinguished from non-disclosing re-tests for the new diagnoses rate to be a more useful measure for estimating incidence trend.Population Health Science
Animated Materiality: The Impact of Architectural Materials, Motion, and Perceived Control on Psychophysiological Symptoms of Stress and Anxiety
No full textThis dissertation emphasizes the critical role of architectural materiality on health by investigating how the perceptual qualities of materials modulate cognitive and physiological symptoms of stress, with a particular focus on individuals with heightened anxiety sensitivity. While architecture often engages questions of space, form, and sustainability, it has yet to fully address how material perception operates on a subconscious level to influence well-being. In response, this work proposes that materials, particularly when activated through movement, rhythm, and multisensory patterning, can become powerful agents in shaping emotional and physiological experience.
Employing an interdisciplinary methodological framework that integrates virtual reality (VR), wearable biometric sensors, and programmable material prototypes, this research systematically quantifies psychophysiological responses while enriching them through qualitative analysis. Three empirical studies were conducted to evaluate the extent to which material perception, specifically; texture, naturalness, color, and rhythmic motion, shapes cognitive appraisal and autonomic recovery during moments of stress.
Findings reveal that natural materials, especially wood, consistently reduce physiological stress markers, while materials animated with rhythmic motion most effectively support parasympathetic recovery, as indicated by lowered electrodermal activity (EDA) and increased heart rate variability (HRV). Unexpectedly, participants who were given control over material behavior during stress experienced diminished recovery and more negative subjective reports, highlighting the cognitive load that perceived agency may impose in emotionally heightened states. Across all studies, a disconnect emerged between subjective preference and physiological response, suggesting that embodied experience often speaks more clearly through the body than through conscious awareness.
The research and methodological contributions in this dissertation offer not only notable potential for advancing the discipline but also raise critical questions about the complexities of instinctual responses, cultural associations, and multisensory interpretations that lie at the heart of what distinguishes materiality from material. These results support the development of animated materiality as both a conceptual framework and design strategy, one that reimagines materials as dynamic, perceptually rich agents capable of responding meaningfully to human states. This shift calls for a rigorous and ongoing exploration of how the synergy of technology, perceptual science, and historical context can be mobilized to address the pervasive mental strain of our time. Ultimately, this work underscores the profound responsibility, and opportunity, architects and designers have to create spaces that not only alleviate stress but also foster resilience and enhance the human condition in meaningful and lasting ways.Advanced Studies Progra
Introduction to Persistent Intervals
No full textWe give an accessible introductory exposition on the concept of persistence intervals from topological data analysis. By carefully crafting numerous examples as well as adopting pedagogical tricks that minimize the direct use of topological tools, we are able to give an efficient, highly readable presentation of the standard theory of persistence intervals that only requires linear algebra as a prerequisite. This is principally an expository thesis, but we also make some minor extensions to the existing literature by giving some basic insights on the nature of local and global barcodes (going a bit beyond what is stated in the conclusion of [LM15]), as well as by showing that the clearing and compression optimizations in [BKR14] can be used to simplify certain aspects of the parallelization algorithm in [LM15] in the case of a simplicial cover of size two.Computer Scienc
Mechanics of Soft-Rigid Interactions: From Wearable Robots to Stingray Skeletons
No full textAcross robots and biological organisms, both rigid and soft materials are frequently encountered, providing either strength/precision or adaptability/safety, respectively. In nature, materials of different stiffnesses are frequently coupled together, producing highly capable "hybrid-stiffness" structures that leverage the benefits of each material in tandem. In robotics, however, most systems are either fully rigid or fully soft, leaving a vast, largely unexplored regime of hybrid-stiffness mechanisms in the middle. This dissertation seeks to study the rigid/soft interactions that are critical to this regime, looking at two particular model systems: a soft wearable robot to assist the shoulder joint (which is heavily influenced by interactions with the rigid-body kinematics of the human shoulder complex) and batoid fish pectoral fins (which comprise an intricate arrangement of rigid skeletal elements embedded within soft muscular tissue).
In the first part of the dissertation, an experimental procedure was developed to characterize the mechanical performance of the shoulder assistance robot in-situ on the human body. Unlike prior characterization techniques that were limited to benchtop settings, this procedure captures the rich rigid-soft interactions between the device and the human body. Significant differences in behavior are noted between these boundary conditions, motivating the importance of studying wearable robots in their actual on-body setting. The results from this investigation then motivated the second portion of the dissertation, investigating and predicting the mechanical hysteresis exhibited by these devices on the body. The proposed modeling framework can reliably predict on-body hysteresis using minimal data collected on each individual wearer, and was demonstrated to outperform existing models from the literature.
In the final portion of the dissertation, the rigid-soft interactions of batoid fish pectoral fin skeletons were studied. The skeletal geometry was parameterized, and variations in these parameters across the fins of three model species were studied. Finite element modeling was then employed to map these geometric parameters onto effective material properties. It was found that the skeleton served primarily to stiffen the in-plane membrane response of the fin while softening the out-of-plane bending response. Moreover, the spatial variations in skeletal geometry led to spatial modulation of the bending properties, with increased compliance observed in regions that exhibit exaggerated bending motions.
These projects involved a combination of experimental characterization, data-driven reduced-order modeling, and physics-informed numerical simulation. Each of these efforts contributes toward the long-term goal of designing highly capable hybrid-stiffness robots that exceed the capabilities of systems constructed with fully rigid or fully soft materials, alone. By studying the rigid-soft interactions of these two models model systems, this dissertation represents an initial step toward this eventual vision.Engineering and Applied Sciences - Engineering Science
The Design of Public Health Insurance Programs and the Welfare of Low-Income Groups
No full textThis dissertation investigates how the structure and incentives of the U.S. health insurance system affect access to care and health outcomes for low-income populations. While public and private insurance expansions have increased coverage, many individuals remain underserved due to fragmentation in insurance responsibility, incentives for selecting the healthiest individuals, and gaps in geographic access to providers. I address these issues through three empirical chapters.
The first chapter examines how fragmented financial responsibility affects insurers’ incentives to provide preventive care. I study a policy change in New York’s Medicaid program that, beginning in 2012, made private Medicaid plans financially responsible for all newborns, including very low birth weight infants previously covered by the public plan. Once they became responsible for covering these costly newborns, private Medicaid plans increased their investment in prenatal care services designed to reduce low birth weight deliveries and neonatal costs. These effects were especially pronounced among enrollees with a high ex-ante risk, suggesting that fragmentation had both efficiency and equity consequences.
The second chapter, co-authored with Tim Layton and Mark Shepard, evaluates a 2017 Medicare Advantage policy that increased payments to insurers for enrolling low-income dual-eligible beneficiaries. Using administrative claims and plan-level data, we find that while payments increased by nearly \$900 per low-income enrollee annually, insurers made only modest improvements to benefit offerings and showed no clear gains in quality or enrollment. In the context of a system characterized by generous over-payments—such as that of Medicare Advantage—our findings suggest that further increasing subsidies may be insufficient to meaningfully change insurer behavior in favor of low-income populations.
The third chapter, co-authored with Amanda Su, studies whether access to Federally Qualified Health Centers (FQHCs) substitutes for formal insurance coverage. Leveraging staggered FQHC openings across counties, we find that FQHCs improve health outcomes—as shown by reductions in all-cause mortality—without reducing insurance enrollment. These findings suggest that physical proximity to care enhances the effectiveness of insurance and serves as an essential complement to coverage.
Together, these chapters highlight that improving healthcare for low-income populations requires more than expanding coverage; it requires better alignment of incentives, simplified insurance structures, and greater investment in the infrastructure that connects people to care.Health Polic
Essays on the Political Economy of the United States
No full textThis dissertation consists of three essays about the contemporary and 20th-century political economy of the United States. A theme throughout is the combination of new or forgotten sources of data to study long-standing questions in economics and political science, and all three chapters pay special attention to issues of measurement and causal inference.
The first essay studies political sorting in the labor market. Merging voter file data and online résumés to create a panel of 34.5 million people, we show that Democrats and Republicans choose distinctive career paths and employers. This leads to marked segregation at the workplace: a Democrat or Republican's coworker is 10% more likely to share their party than expected based on local partisan shares. Then, we ask whether segregation arises because jobs shape workers' politics or because workers' politics shape their job choices. To study the first, we use a quasi-experimental design leveraging the timing of job transitions. We find that uncommitted workers do adopt the politics of their workplace, but not workers who were already registered Democrats or Republicans. To study the second, we measure the intensity of workers' preferences for politically compatible jobs using two survey experiments motivated by the observational data. Here, we find that the median Democrat or Republican would trade off 3% in annual wages for an ideologically congruent version of a similar job.
The second essay asks how childhood environment shapes political behavior. We measure young voters’ participation and party affiliation in nationally comprehensive voter files and reconstruct their childhood location histories based on their parents’ addresses. We compare outcomes of individuals who moved between the same origin and destination counties but at different ages. Those who spend more time in the destination are more influenced by it: growing up in a county where their peers are 10 percentage points more likely to become Republicans makes them 4.7 percentage points more likely to become Republican themselves upon entering the electorate. The effects are of similar magnitude for Democratic partisanship and turnout. These exposure effects are primarily driven by teenage years, and they persist but decay after the first election.
The third essay focuses on the 400,000 Black men who were drafted into the National Army during World War I, where they toiled in segregated units and received little formal training. Leveraging novel variation from the WWI draft lottery and millions of digitized military and NAACP records, we document the pioneering role these men played in the early civil rights movement. Relative to observably similar individuals from the same draft board, Black men randomly inducted into the Army were significantly more likely to join the nascent NAACP and to become prominent community leaders in the New Negro era. Corroborating historical accounts about the catalyzing influence of institutional racism in the military, we show that increased civic activism was driven by soldiers who experienced the most discriminatory treatment while serving their country.Economic
The effect of urban greenspace on the surrounding community’s mental health. Did the long-term closure of East River Park effect the psychological well-being of its closest neighbors?
No full textThere is much empirical evidence that supports a connection between Subjective Well-Being (SWB) and exposure to nature. There is further evidence that urban environments tend to cause stress and increase negative affect (NA) and decrease positive affect (PA) and that green spaces tend to increase PA and decrease NA, making the need for greenspace within urban environments all the more palpable. This study takes the case of East River Park’s (ERP) extended closure (for the purpose of increasing flood protection due to extreme weather) and compares local residents’ feelings about the park in its open condition and in its closed and under construction condition. This study found that, following the trend of other similar research, PA increased and NA decreased in the park’s open condition, and the opposite was true in the park’s closed/under construction condition. Direct questions about mental health revealed that 86% of polled residents thought that the closure effected the community’s mental health and of those, 85.4% believed that effect was negative. Finally, in qualitative analyses 96% of participants highlighted emotions related to PA when discussing their experience when the park was open and 90% of residents discussed emotions reflecting NA when the park was closed.Extension Studie
Erzählweisen des Vergessens. Ellipsen im Roman von Theodor Fontane bis W. G. Sebald
No full textThis dissertation, Erzählweisen des Vergessens: Ellipsen im Roman von Theodor Fontane bis W.G. Sebald, examines the interconnections of forgetting and narrative structures in major works of German prose fiction from c. 1870–2001. I understand forgetting as an absence hinting at a hidden presence, a definition that complicates our understanding of meaning-making in texts. Typically, a present sign, for example a word, brings to mind something absent, whereas here, an omission acts as a sign of something present. Engaging with methodologies from cultural memory studies, narratology, and philosophy, I argue that the way forgetting creates meaning is akin to the way an ellipsis works: an omission is marked and subsequently filled by contextual cues. As a critical textual expression of forgetting, the ellipsis produces meaning in a text by illuminating the repressed aspects of cultural memory, the unspeakable, and societal trauma. I demonstrate that elliptical forgetting allows late realist texts by Fontane and Raabe to participate in a veiled antisemitic discourse, rendering “the Jew” the constitutive “Other” of the German nation-state around 1900. I also show how elliptical forgetting conveys the traumatic war experience of the Great War through experimental form, disrupting linear time in Alfred Döblin’s works, and how W. G. Sebald strategically employs forgetting to address both the trauma of the Holocaust and the failures of German memory politics. As yet there has been no such analysis of forgetting as a specific characteristic of narration itself, and this work shows how elliptical forgetting links memory politics and aesthetics, ultimately enabling literature to partake in key discussions of memory politics.Germanic Languages and Literature