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Essays in Economic History and Social Policy
No full textThis dissertation contains three chapters; the first two concern the economic history of education in the United States, and the third contemporary social policy. In the first chapter, I study inequality in college towns. I start with the observation that human capital institutions create social benefits that extend far beyond their physical reaches. However, the long-run equilibrium impact of such institutions on economic mobility and income segregation within the places they are located is less well understood. I establish the descriptive pattern that today, places with colleges have higher income segregation and lower economic mobility. To establish long-run causal effects, following Andrews (2023) I compare college placements with quasi-random runner-up towns in the historical college establishment process. I find that college establishments cause higher levels of contemporary income segregation but have little effect on economic mobility. As a mechanism, I show that college establishments cause larger growth in employment concentration in professional services.
In the second chapter, co-authored with Danielle Graves Williamson, we study establishments of all-white private schools in the mid-20th century South. Institutionalized backlash may be an important mediator of social progress. In the post-Brown v. Board (1954) U.S. South, white citizens established explicitly segregationist private schools. These “segregation academies” effectively impeded efforts to integrate schools, especially in rural areas (Williamson 2024). In this chapter, we study the consequences of this preservation of segregation on historical voting behavior and later racial attitudes in the Southeast. We argue that segregation academies entrenched a culture of racial division in places that otherwise would have made steps toward integration. Using difference-in-differences designs around the openings of segregation academies, we find a suggestive contemporaneous shift away from the Democratic party in treated counties emerging in the medium-run. Studying later retrospective racial attitudes, we find no accompanying shift in conservative racial attitudes, but an increase in racism. We discuss potential explanations to reconcile these patterns.
Finally, in the third chapter, co authored with Kelsey Pukelis and Alice Heath, we conduct a nationally-representative survey to study stigma in the context of the Supplemental Nutrition Assistance Program (SNAP). Stigma may reduce participation in social safety net programs and impose utility costs on individuals already receiving benefits. But who experiences stigma, how it affects participant decisions, and whether it can be reduced remain unclear. We find that stigma varies by political affiliation and SNAP participation status: Democrats report lower levels of stigmatizing beliefs than Republicans, and SNAP participants report lower levels of stigma than non-participants. Three randomized messaging interventions designed to reduce stigma have heterogeneous effects: they decrease stigma among Democrats and those with low expectations of judgment from others, increase stigma among Republicans, and have no effect on those with high expectations of judgment. One intervention that addresses a common zero-sum concern—that enrolling in SNAP prevents others from receiving benefits—increases interest in take-up among eligible non-participants while decreasing overall support for SNAP spending.Public Polic
Examining Extra-Classical Receptive Field Effects in the Long-Range Modulatory Feedback Model
No full textVisual perception research highlights the brain’s ability to dynamically interpret visual input through
classical (CRFs) and extra-classical receptive fields (ECRFs). While CRFs focus on localized visual
features, ECRFs provide contextual modulation critical for tasks like contrast normalization,
figure-ground segregation, and boundary detection. Despite their efficacy in object recognition,
feedforward deep neural networks (DNNs) lack mechanisms for context-dependent modulation, limiting
their biological plausibility.
This study investigates whether a biologically inspired long-range modulatory (LRM) feedback model
exhibits ECRF-like properties observed in biological vision. Using visual stimuli directly adapted from
Cavanaugh et al. (2002), which systematically varied in size, orientation, and spatial frequency, we
analyzed kernel activations across two processing passes: Pass 1 (feedforward) and Pass 2 (feedback).
Receptive field properties were quantified using metrics such as the Grating Summation Field (GSF) and
Suppression Index (SI) to assess center-surround interactions.
Results revealed that Pass 2 induced significant changes in spatial integration, including an expansion of
the excitatory summation field (higher GSF values) and increased suppression effects in the first
convolutional layer, resembling V1 feedback mechanisms. However, the second layer exhibited high
variability, with kernels responding inconsistently to feedback, ranging from suppression to
amplification, suggesting heterogeneous effects of modulation. Additionally, Pass 2 responses displayed
variable participation across kernels, with nonzero activations distributed unevenly compared to Pass 1,
which exhibited more uniform activation.Computer Scienc
The Learning Hypothesis on Spatial Receptive Field Remapping
No full textThe spatial pattern of grid cells changes due to information such as the location of rewards. Past research has discovered that after rats learn the location of rewards in a cheeseboard environment, their grid cells activate more near reward locations, distorting the grid pattern. However, it is unknown whether this distortion has any purpose at a population level. In this work, we use reinforcement learning (RL) theory to explain how changes in spatial activation patterns could be the result of the agent trying to optimize learning progress such as learning speed or convergence learning error. Here, we assume that distortions of the grid patterns correspond to changes in features in temporal difference (TD) learning. First, we show that with fixed features, parameters such as learning rate (η) and batch size (B) linearly change the TD learning convergence learning error. Specifically, the convergence learning error is proportional to O(η/B). Though this result depends on a Gaussian approximation when feature dimension is high, we demonstrate the linear scaling phenomenon on continuous complex environments such as MountainCar-v0. Second, we show that using an evolutionary method to adjust radial basis function features (place cell features) would evolve features that are centered near reward locations. Finally, we use experimental data from rats' medial entorhinal cortex (MEC) to show that the features after learning provide faster TD learning convergence speed and lower convergence error. These results support the theory that animals change their perceptions to optimize learning progress.Computer Scienc
Association of Diabetes with Changes in Blood Pressure & Heart Rate Variability during Hemodialysis: Insights from The Frequent Hemodialysis Network Daily Trial
No full textProject 1 Abstract
Title: Association of Diabetes with Changes in Blood Pressure during Hemodialysis:A Secondary Analysis of the Frequent Hemodialysis Network Daily Trial.
Introduction
Diabetes mellitus is a common cause of kidney failure and is often complicated by autonomic neuropathy, which may have implications for blood pressure (BP) homeostasis during hemodialysis (HD).
Methods
In this post hoc analysis of the Frequent Hemodialysis Network (FHN) Daily Trial, we used random effects Poisson and linear regression models to estimate the association of diabetes (versus not) with intra-dialytic hypotension (IDH) and peri-dialytic BP parameters, respectively. We tested for differential associations according to the randomized treatment (6/week vs 3/week HD) and pre-HD systolic BP.
Results
Of the 244 patients with intra-dialytic BP data, 100 (41%) had diabetes at baseline. The mean age was 51 ± 14 years; 39% were female. In adjusted models, diabetes (vs. not) was associated with a 93% higher risk of developing IDH (IRR 1.93; 95% CI 1.26, 2.95). There was no evidence that the randomized treatment assignment modified the association between diabetes and IDH (P-interaction=0.32), but more potent associations were noted among those with higher pre-HD systolic BP (P-interaction .001). Diabetes (vs. not) was associated with a lower adjusted nadir intra-HD BP (-4.2; 95%CI -8.3, -0.2 mmHg), but not with the pre- or post-HD systolic BP.
Conclusions
Among participants of the FHN Daily trial, patients with diabetes had a higher risk of intra-dialytic hypotension and lower nadir intra-HD systolic BP than patients without diabetes, even when undergoing HD up to 6 times per week.
Project 2 Abstract
Title: Association of Diabetes with Heart Rate Variability during Hemodialysis: Insights from the Frequent Hemodialysis Network Daily Trial.
Introduction
Autonomic dysfunction is common among patients with diabetes receiving hemodialysis (HD). We wished to explore the association of diabetes with heart rate variability (HRV; a surrogate of autonomic dysfunction) and whether HRV mediates the association of diabetes with intra-dialytic hypotension (IDH).
Methods
In this secondary analysis of the Frequent Hemodialysis Network Daily Trial, we performed: 1) random effects linear regression to estimate the association of diabetes with log-transformed low-frequency power [LF, proxy of sympathetic activity], high-frequency power [HF, proxy of parasympathetic activity], ratio of LF/HF (proxy for sympathovagal balance), and standard deviation of the normal-to-normal R-R interval [SDNN] measured at baseline and 12-months); 2) linear regression to explore the association of diabetes with changes in HRV parameters over 12 months. Models were adjusted for age, sex, designated race, height, access type, HD vintage, history of heart failure, pre-HD systolic BP, heart rate, ultrafiltration rate, hemoglobin, serum albumin, beta-blocker use, calcium channel blocker use, diuretic use, left ventricular mass, and randomized treatment assignment.
Results
Of the 198 patients without baseline atrial fibrillation, 82 (41%) had self-reported diabetes. In adjusted random effects models, diabetes (vs. no diabetes) was associated with lower SDNN –18% (95%CI –27, –9) on a per session basis. The presence of diabetes was not associated with differences in LF 7% (95%CI –20, 43), HF 10% (95%CI –10, 33), or LF/HF –4% (95%CI –19, 14). Diabetes (vs. no diabetes) was not associated with a change from baseline to 12 months in any HRV parameter. SDNN did not attenuate the observed association of diabetes with IDH.
Conclusions
Among participants in the FHN Daily Trial, diabetes (vs. no diabetes) was associated with 18% lower SDNN. The association of diabetes with IDH did not appear to be mediated by SDNN. The reasons for higher rates of IDH in patients with diabetes remain elusive.
Graduate Educatio
Management of Charge Carriers in Aqueous-Nonaqueous Phases and Interfaces in Electrochemical Systems for Energy Storage and Conversion
No full textThe escalating global impact of climate change, driven in large part by fossil fuel combustion and resultant CO₂ emissions, demands urgent innovation in sustainable energy systems. The rapid expansion of renewable energy sources — such as wind and solar — has intensified the need for energy technologies such as grid scale storage systems that can accommodate their inherent intermittency. Concurrently, breakthroughs in electrosynthesis have highlighted the potential of electrochemical systems to convert renewable electricity into valuable chemicals and fuels. In many of these applications, the efficient management of charge carriers, particularly protons and hydroxide ions, is essential for achieving high selectivity, energy efficiency, and operational longevity. The transport and control of ions and electrons across aqueous-nonaqueous and solid-liquid interfaces can further open up the opportunity of using electrochemistry in nonaqueous systems.
This dissertation presents a comprehensive investigation into the control and optimization of transport of protons, hydroxide ions, and ion-coupled electrons across aqueous and nonaqueous solutions and their interfaces to advance electrochemical technologies for sustainable energy storage and conversion.
In Chapter Two, a mild pH‐decoupling aqueous redox flow battery is developed with a practical pH recovery system. By separating the pH conditions of the negolyte and posolyte, the design achieves cell voltages well above 1.23 V. The crossover of proton/hydroxide ions is investigated to assure high Coulombic efficiency and long-term stability, which are essential for scalable grid energy storage.
Chapter Three introduces an electrochemical acid-base generator designed for decoupled carbon management. By minimizing the acid-base crossover, the system produces concentrated acid and base streams at high current efficiency and low energy cost. This device is applied to carbon capture scenarios — from simulated flue gas to direct air capture — demonstrating its potential for integrated decarbonization strategies.
In Chapter Four, we reveal that redox mediators that operate via proton-coupled electron transfer (PCET) can be explored to mediate electrochemical hydrogen storage or ion exchange.
Chapter Five extends the approach to electrosynthesis by leveraging interfacial PCET at aqueous-nonaqueous interfaces, bridging the aqueous electrochemistry and nonaqueous chemistry to electrifying nonaqueous synthesis. This work demonstrates how aqueous redox mediators can transfer proton-electron pairs as a charge-neutral fragment into/onto nonaqueous phases to drive selective chemical synthesis, exemplified by the electrification of industrial hydrogen peroxide production and nonaqueous organic hydrogenation, solving the long-existent challenge of achieving high current density and high efficiency during nonaqueous electrosynthesis.
Collectively, the studies establish a unified framework for managing charge carriers in electrochemical systems, offering key insights into interfacial transport phenomena and laying the groundwork for next‐generation, sustainable energy technologies. The innovations presented here promise to improve both the efficiency and economic viability of energy storage, carbon management, and electrosynthetic processes.Engineering and Applied Sciences - Engineering Science
La Lucha (The Fight): Strengthening Latine Students’ Sense of Belonging in Hamilton County Schools
No full textBy 2030, Latine students will account for 30% of all public schools enrollment in the United States (Jimenez, 2022). The lack of cultural awareness and ethnic representation among school staff, combined with the anti-immigrant rhetoric at the state, particularly in the Midwest and South, and federal level, threatens Latine students’ sense of belonging. A strong sense of belonging is critical to all students’ academic and social success, as shown by education theorists and practitioners. It is paramount to the future of the United States that Latine students are provided with the necessary support to experience belonging both inside and outside of schools.
This capstone examines my 10-month residency in Hamilton County Schools (HCS), exploring the complexities and opportunities in strengthening the sense of belonging for Latine students. The district’s Latine student population has tripled over the last twelve years. By collaborating with a steering committee and conducting empathy interviews, surveys, and focus groups, I examine how Latine middle and high school students—across diverse backgrounds, including U.S.-born and undocumented—experience belonging, or lack thereof, in HCS and the broader community. The data reveals three common themes experienced by some of the Latine students: bullying and discrimination within and across ethnic and racial groups, limited opportunities to celebrate their cultures, and, for linguistically diverse learners, difficulties engaging with classes due to the English-Only law, which mandates instruction be taught in English.
Grounded in research on belonging, child development, culturally responsive pedagogy, and human-centered design thinking, my strategic project led to the creation of community partner coordination, professional learning opportunities, policy protocols, and storytelling to address the rapidly changing sociopolitical environment. The recommendations emphasize advocating for undocumented students and support their college and career pathways over the next four years, alongside other key strategies. Finally, this contribution to the field concludes with a call to action and reflective questions for all individuals within the education sector to join la lucha (the fight) to nurture the culture, dreams, and voices of Latine students.Educatio
Enteroendocrine regulation of metabolism and innate immunity in Drosophila melanogaster
No full textDespite comprising a very small percentage of the total intestinal epithelium cell population, enteroendocrine cells (EECs) collectively form the largest endocrine organ in the body, secreting over 20 peptide hormones, or enteroendocrine peptides (EEPs), that regulate several physiological processes, including feeding behavior, metabolism, and immunity. Drosophila melanogaster, also known as the common fruit fly, shares structural and functional homology with the mammalian gastrointestinal tract and has therefore served as an excellent model organism to study intestinal physiology. My thesis work explores the role and regulation of the Drosophila EEP tachykinin (Tk) in the context of innate immunity and intestinal and systemic lipid metabolism. Previous work by the lab has established that activation of innate immune signaling in EECs induces expression of Tk and subsequent production of antimicrobial peptides (AMPs). In the first part of my thesis work, I discovered that, in addition to AMPs, Tk activates expression of Peritrophin-15a, a chitin-binding protein that is part of the protective peritrophic matrix (PM) that lines the intestinal epithelium. I further found that Peritrophin-15a is necessary for robust intestinal colonization by the pathogen V. cholerae and that, in addition to Drosophila, other arthropods that associate with V. cholerae in the environment express close structural homologs of Peritrophin-15a. Our findings suggest that V. cholerae might exploit activation of the host innate immune response and upregulation of Peritrophin-15a to increase adhesion to the intestinal surface of environmental arthropod hosts. Much like mammalian EECs, Drosophila EECs express nutrient transporters and G protein-coupled receptors (GPCRs) that sense intestinal nutrient status to regulate EEP production. In the second part of my thesis work, I found that the EEC-exclusive GPCR GulpR regulates expression of Tk and other EEPs. I also report that, through Tk, GulpR modulates utilization of systemic lipid stores when flies experience starvation but not infection stress. This suggests that activation of lipid mobilization in response to nutrient limitation and infection are regulated via different mechanisms. Overall, my thesis work identifies a GPCR that regulates expression of Tk and other EEPs in Drosophila, discovers additional roles of Tk in modulating innate immunity and metabolism, and identifies a protein produced by arthropods that may contribute to the survival and persistence of the human pathogen V. cholerae in the environment.Biological and Biomedical Science
The Sociology of Summer Camp: Examining Demographic Discrepancies in Perceived Student Outcomes Through the Organizational Context of Summer Programs
No full textIn the context of widening learning gaps and growing educational inequities, this thesis attempts to make sense of the responsibility placed on summer programs to reduce learning gaps. My thesis takes a step back to understand the organizational sociology of summer camp programs before zooming in to examine demographic discrepancies in perceived outcomes from a longitudinal case study. The goal of this research project is hence twofold. First, I theoretically frame the mechanisms within summer camp in the context of organizational sociology. Then, I quantitatively analyze demographic factors that impact the perceived outcomes of students from the Summer Urban Program (SUP) through the lens of this sociology of summer camp theoretical framework. In particular, I ask how do the demographics of counselors and students impact the perceived outcomes of students in the classroom at summer camp? How can theoretical understandings of summer camp mechanisms explain these impacts?
For this thesis, I explore race and gender as key demographics in a stepwise regression modeling approach, utilizing 2019-2023 data from SUP’s family surveys. I focus on Academic, SEL, Inside of Camp Interaction, and Outside of Camp Interaction outcome variables. My findings reveal that gender and racial match in the classroom do not have any effect on student learning outcome scores, at least through parent perceptions. Lower scores were identified for children with gender queer/nonbinary and male counselors and for Native American children. Asian/Pacific Islander counselor race and child race also had consistently lower outcome scores. Students with white counselors had higher scores than other racial categories for most outcomes. Other factors that correlated with higher scores were counselor expertise, child age, and child household income.Computer Scienc
Partisan Polarization in Local Politics
No full textA growing body of scholarship investigates the extent to which national partisan polarization filters down to the local level. There has been little evidence, however, on: (1) the size of the local partisan divide; (2) the extent to which it varies by policy issue; and (3) how these divides compare at the elite and the mass public levels. Using responses to questions about local policy preferences from nearly a decade of nationwide surveys of mayors and from 25,521 members of the public in 87 cities between 2020 and 2023, we uncover notable variation in local partisan polarization. We find substantial polarization across a number of local policy issue areas and less in others. Just as others have found at the national level, we find that elite partisan polarization is more substantial than it is among members of the public on nearly every policy issue for which we have directly comparable data. We also find, by using the subset of data for which we have mayors and their constituents answering identical questions, that mayors take positions aligned with their constituents’ about 61% of the time. While Democratic mayors align with their Democratic constituents more than with their Republican ones, and Republican mayors do the opposite, the differences are modest against the background of polarization in America. Together, these results reaffirm the pre-eminence of partisanship in the formation of public opinion, challenge a traditional consensus that local politics is apartisan, and establish scope conditions on when partisanship might shape the policy outputs of local government.Author's Origina
Characterizing retroactive jealousy: Evidence from network, machine learning, and qualitative approaches
No full textRetroactive jealousy is a distressing and poorly understood phenomenon characterized by intrusive thoughts, compulsive behaviors, and emotional distress in response to a romantic partner’s past relationships. This dissertation aims to advance understanding of retroactive jealousy through a series of empirical investigations spanning network analysis, machine learning, and computational linguistic approaches. In Study 1, we examine the symptom structure of retroactive jealousy and its relationship to obsessive-compulsive disorder (OCD), relationship OCD (ROCD), and borderline personality disorder (BPD). We find that retroactive jealousy symptoms do not form a strongly interconnected network, suggesting that the condition may not represent a coherent syndrome. In Study 2, we apply latent profile analysis to identify potential subtypes of retroactive jealousy based on behavioral strategies. Results reveal subtle differences in coping styles but limited evidence for stable or clinically distinct subtypes. In Study 3, we explore cognitive mechanisms associated with retroactive jealousy using open-ended responses analyzed through computational linguistics. We find that higher retroactive jealousy severity is associated with lower self-reported cognitive flexibility and greater use of certainty-related language, suggesting a role for rigid cognitive schemas. Drawing on work in the philosophy of mental illness, we also consider the possibility that retroactive jealousy reflects a historically and culturally situated expression of distress shaped by modern romantic ideals and digital media. Together, these studies suggest that retroactive jealousy may not be best conceptualized as a form of an existing disorder category, but rather as a culturally embedded cognitive-affective experience that raises broader questions about the nature of emergent psychopathology.Psycholog