In the United States, there exist both overt and covert barriers limiting some students' access to high-quality schools, creating systematic inequities that affect labor market outcomes. Insurmountable challenges in dismantling these barriers have led policymakers to explore the capacity for school choice reforms as a means to improve student outcomes. The decentralized nature of public education in the United States has allowed for wide experimentation across states and districts, but the heterogeneous implementation of policies has also generated mixed results and many open questions. This dissertation contains three essays that aim to tackle some of these open questions. In chapter 2, I outline a conceptual framework that provides some structure for subsequent chapters. The purpose of this chapter is present a benchmark model where the typical benefits that motivate contemporary school choice reforms materialize. The contributions of this chapter are to generate an empirically-oriented model at the cost of several simplifying assumptions. Other models in the literature take an opposite approach, but the primary contributions of this dissertation are empirical so I opt for an empirically-oriented theoretical framework. I link this model to the subsequent chapters in two ways. First, a key statistic that summarizes families' expected welfare gains from the program is an important covariate for the empirical analysis in Chapter \ref{sec:empiricalchapter}. Second, some of the simplifying assumptions regarding perfect information and preferences receive cursory treatment in Chapter \ref{sec:empiricalchapter} and are the focal point of a field experiment discussed in Chapter \ref{sec:experimentchapter}. In chapter 3, co-authored work with Caitlin Kearns, I study how the demand and supply for school quality can evolve in response to a policy---the Zones of Choice (ZOC) program--that changed the underlying choice and competitive structure that families and schools face. The contributions of this chapter are to provide empirical evidence tackling the questions surrounding access, competition and student-school match quality. I find that the achievement among students enrolled in ZOC schools increases, with gains sufficiently large to eliminate eleventh-grade achievement gaps that existed in the years before the policy expansion. I distinguish between effects driven by parents choosing schools that best suit their children's needs and competitive effects induced by the policy, and find most of the student gains are driven by general improvements in school quality as measured by school value-added. The lack of improvements in student-school match quality are in part due to the homogeneous set of students within each zone, eliminating the scope for improvements in student-school match quality based on observable student characteristics. I find evidence that schools exposed to more competition (as captured by a statistic derived in Chapter \ref{sec:modelchapter}) improved more, providing suggestive evidence for a competitive effects story. I then provide suggestive evidence that parent's selected schools in a way that incentivized schools to compete on quality, a finding that contrasts a growing body of evidence suggesting otherwise. The highly segregated nature of each zone of choice can maybe explain differences with the past literature. In settings where parents can use race or income to proxy for school quality, they will do so, but in segregated neighborhoods parents will use other proxies that are correlated with school effectiveness. This presents a tradeoff present in the ZOC setting: short-run gains in terms of reductions in within-district inequality in exchange for potentially negative long-run effects through the entrenchment of school segregation in the district. Information and preferences are the focal point of Chapter 4, where I report the findings from a field experiment I conducted in Fall 2019. My contribution is to study parental preferences through an information provision experiment, linking the information provision literature with another growing body of research studying parents' preferences for schools. By distributing information to students' households I address the information channel, and in addition provide settings where some parents are perfectly informed about both school and peer quality, allowing me to study relative preferences for peer and school quality. In addition, I explore the role that social interactions play in determining schooling decisions. I corroborate my findings from Chapter \ref{sec:empiricalchapter} by showing that parents not receiving any information tend to place higher weight on school quality than peer quality. Among parents receiving information, I first document evidence that their most-preferred schools changed in terms of quality and peer composition. I then provide evidence showing that the information campaign led to increases in relative preferences for school value-added, suggesting information campaigns can produce changes in choices that affect school quality. Through various avenues, I provide evidence of large and salient treatment spillovers, indicating substantial interactions between parents. The prevalent role of social interactions could introduce disadvantages to groups with less informed networks in this and other settings.

This dissertation is a phenomenological anthropology of intersubjectivity in the design of healthcare architecture. Based on 12 months of ethnographic fieldwork with architectural designers in the San Francisco Bay Area, this dissertation details how architectural designers derive and enact their understandings of the healthcare professionals and patients for whom they design. Since the 1960s, many architects have taken up an orientation toward design that I herein refer to as “Methodological User-Centricity” (MUC). The premise is simple: better design hinges on better empirical knowledge of the people being designed for, and that knowledge is best acquired by what are often social-science-inspired methods. One of the most influential encapsulations of this orientation in design today (in architecture and beyond) is “empathy”. The healthcare architects in this ethnographic study believed “empathic” knowledge of “users”—including patients, doctors, nurses—was essential to improving healthcare, and sought to develop this understanding of occupants through games, interviews, and other methods for learning about users’ needs, values, and experiences. Situated in this context, this dissertation examines the background premises and methods through which these architectural designers enact their specific forms of constituting others and intervening in the built environment on their behalf. Working from data running the gamut of architectural activities from initial stages of user research and conceptualization, to completion and retrospective evaluation by both designers and end-users, the dissertation analyzes the diverse modalities of experience by which members of architectural project teams orient themselves to users’ needs and possibilities. In doing so, the dissertation approaches architecture as a polymorphous response to others, one ultimately rooted in manifold forms intersubjectivity and degrees of social understanding. Nevertheless, this dissertation also presents a critical analysis of unintentional shortcomings arising through unequal user representation in architectural designers’ research with healthcare institutions.

Described in this dissertation work are the paths, dead-ends and detours involved in eventually securing an enantiospecific formal synthesis of (+)-7,20-diisocyanoadociane (DICA) via Corey’s dione, a project spanning early 2012 to early 2016. Highlighted is the isolation and biological background to DICA and isocyanoterpenes in general, in addition to the prior synthetic art for the preparation of cycloamphilectane and isocycloamphilectanes. Initial attempts at an entry into the DICA framework included a polyene cyclization, Diels–Alder/aldol condensation and reductive enone coupling strategy. Although these routes were unsuccessful they served as essential evolutionary precursors to the eventual completion of Corey’s dione. Efforts to utilize Swaminathans oxy-Cope/transannular Michael cascade to construct the perhydropyrene scaffold of DICA led to a structural reassignment. Further mechanistic investigations into this reaction elucidated that the transannular Michael reaction was in fact under kinetic control. A phenanthrenone reduction route led to an unexpected stereochemical outcome that could be useful for predictive control of either cis or trans outcomes. An enantiospecific formal synthesis of DICA was eventually secured through a dihydronaphthalene reduction. A general approach to multiple C7-isocyano(iso)cycloamphilectanes is also discussed.

Our computers, phones, and other smart devices are running a vast and ever increasing amount of software. This provides us with many capabilities that we make use of throughout our everyday lives. However, it also brings with it a large attack surface, wherein vulnerabilities could lie. A single vulnerability in any component could be maliciously exploited to gain access to private information or cause damage. This weakness is compounded by the imbalance between attackers and those who secure software; defenders must eliminate all of the vulnerabilities to have secure software, whereas an attacker may only need one vulnerability to be able to craft an exploit. Of course, all of this software cannot be audited, checked for bugs, and made secure manually; effective automated techniques are needed.

One of the most common causes of insecure software is memory corruption vulnerabilities.Memory corruption is frequently found in unsafe languages, such as C and C++, and can take many forms. Currently, the main methods of finding memory corruption are fuzzing and static analysis. However, both of these have major weaknesses that prevent finding many of the bugs present in modern software. The goal of my research is to improve upon the available techniques to make them more capable of finding bugs in real-world programs. To this end, the first work of my PhD identifies a key weakness in fuzzers---that they are impeded by difficult checks, such as string comparisons or magic numbers. With this in mind, we designed a new tool that combines fuzzing with symbolic execution, such that it can now solve for difficult checks and be able to continue fuzzing beyond them.

Of course, finding bugs is only one part of the problem. In my next work, I worked on a novel application of symbolic execution to hot-patch vulnerable devices. Many IoT devices are not created with any built-in mechanism to update, and could be an easy target for attackers should a vulnerability be discovered. My research allows such devices to be automatically patched in event that a code execution vulnerability is found, without any support needed from the device itself.

In the final two projects of my PhD, I identify fundamental properties of fuzzers and use these to create new paradigms of fuzzing, which can find more vulnerabilities.One work formalizes how fuzzers find new inputs to mutate. Then, using this formalization, I design new strategies for fuzzing, which show improved capabilities for finding bugs. The last work I present here is a new technique for fuzzing JavaScript engines, called \emph{Token-Level Fuzzing}. Instead of mutating individual bytes, Token-Level Fuzzing mutates entire tokens, replacing them with another valid token. Using this technique, we are able to find bugs which no other published fuzzer has found. I hope the techniques presented here can bring automated bug finding a step forward and be further built upon, as we try to eliminate memory corruption vulnerabilities.

In this thesis, I show that we can leverage the structure of binary programs and the essential properties of the data which they process to improve the effectiveness of vulnerability discovery based on fuzzing.