VictorJuiz/thesis huggingface dataset:
Secure Computing using Certified Software and Trusted Hardware

Building applications that ensure confidentiality of sensitive data is a non-trivial task. Such applications constantly face threats due to vulnerabilities in the application's code, or infrastructure attacks due to malicious datacenter insiders and exploits in the lower computing layers (i.e. OS, hypervisor, BIOS, firmware) that the application relies upon./nThis dissertation presents a novel approach for developing and verifying applications with provable confidentiality guarantees, even in the presence of such privileged adversaries. Our primary defense against infrastructure attacks is the use of trusted primitives such as Intel SGX enclaves, for isolating sensitive code and data within protected memory regions; enclaves are inaccessible to all other software running on the machine (i.e. OS, hypervisor, etc.), thus removing these large software layers from the trusted computing base (TCB). A central question addressed by this thesis is how the trusted hardware primitives can be used safely to build the trusted components of modern applications with provable guarantees. Prior experience suggests that even expert developers write unsafe programs that leak sensitive data due to programming errors and side channel attacks. To address this problem, this thesis makes contributions in formal threat models, modeling and specification of trusted platforms, and techniques to verify confidentiality properties of enclave programs./nFirst, this thesis formalizes adversary models, an abstract, interface-level model of trusted platforms (including Intel SGX and MIT Sanctum), and formal semantics of enclave execution. This formal framework is required for reasoning about a program's behavior in the presence of a privileged adversary. Next, this thesis presents tools and techniques for certifying confidentiality (at the binary level), a property that we decompose into the following desiderata: 1) lack of explicit leak of secrets via enclave's outputs, 2) protection against certain side-channel leaks --- we only remove leaks via page-level memory access pattern, which is a new channel for privileged adversaries. For both desiderata, we develop verification tools and evaluate them on application's binaries including Map-Reduce programs from the Microsoft VC3 system, SPEC benchmarks, and several machine learning algorithms.

Advisor: Seshia, Sanjit A
Targeted Maximum Likelihood Estimation for Evaluation of the Health Impacts of Air Pollution

The adverse effects of air pollution on human life is of serious concern for today’s society. Two population groups that are especially vulnerable to air pollution are pregnant women and their growing fetuses, and the focus of this thesis is to study the effects of air pollution on these populations. In order to address the methodological limitations in prior research, we quantify the impact of air pollution on various adverse pregnancy outcomes, utilizing machine learning and novel causal inference methods. Specifically, we utilize two semi-parametric, double robust, asymptotically efficient substitution estimators to estimate the causal attributable risk of various pregnancy outcomes of interest. Model fitting via machine learning algorithms helps to avoid reliance on misspecified parametric models and thereby improve both the robustness and precision of our estimates, ensuring meaningful statistical inference. Under assumptions, the causal attributable risk that we estimate translates to the absolute change in adverse pregnancy outcome risk that would be observed under a hypothetical intervention to change pollution levels, relative to currently observed levels. The estimated causal attributable risk provides a quantitative estimate of a quantity with more immediate public health and policy relevance.

Advisor: Petersen, Maya
Estimating Causal Effects of Occupational Exposures

Estimates of the risk of occupational exposures are typically based on observational workplace studies that are subject to bias due to the healthy worker survivor effect (HWSE), a ubiquitous process that results in the healthiest workers accruing the most exposure. This body of work is concerned with the estimation of causal effects of occupational exposures from observational workplace studies, in the context of the HWSE./nWe estimate the effect of cumulative exposure to straight, soluble, and synthetic metalworking fluids (MWFs) on the incidence of colon cancer in the United Autoworkers-General Motors (UAW-GM) cohort. We use longitudinal targeted minimum loss-based estimation (TMLE) to compute the 25-year risk difference if always exposed above compared to if always exposed below an exposure cutoff while at work. Exposure cutoffs were selected a priori at the median of exposed person-years among colon cancer cases. Risk differences are 0.038 (95% CI = 0.022 to 0.054), 0.002 (95% CI = -0.016 to 0.019), and 0.008 (95% CI = 0.002 to 0.014) for straight, soluble, and synthetic MWFs, respectively. By control of the time-varying confounding on the casual pathway that characterizes the HWSE, TMLE estimated effects that were undetectable in earlier reports./nMost workers in UAW-GM were hired decades before the reporting of incident cancers began. Incident cancers that occurred before the start of reporting were left filtered. We show that if ignored, left filtering can lead to downward bias in exposure effect estimates. Further, we propose a novel delayed-entry adjusted Kaplan-Meier estimator that controls for time-varying confounding, and permits delayed risk-set entry. The estimator results in little bias in simulated datasets when the outcome is sufficiently rare./nIn addition to dynamic (realistic) interventions that assign exposure according to workers' employment status, causal contrasts can be defined under static (etiologic) interventions that additionally prevent leaving work. Causal effect estimates of the two classes of interventions can differ substantially. While ideally the choice of intervention would be driven by the research question, in practice it may be dictated by the available data. Furthermore, when estimates of the long-term etiologic effects of occupational exposures are not available, guidelines for exposure limits may be based on studies that estimated effects of realistic interventions. In a simulation study we investigate the conditions under which the two effect measures are comparable, and identify factors that drive the differences between the two.

Advisor: Eisen, Ellen A
Complementary 4D-Flow and CFD Analysis Methods for Investigating Pathological Hemodynamics

The pathology of many cardiovascular diseases is believed to be heavily tied to local hemodynamics. A positive feedback loop of remodeling and unhealthy flow conditions can lead to blood vessel abnormalities, such as aneurysms, stenoses, and plaques. Doctors use medical imaging techniques to visualize vascular disease within patients. However, while treatments based on these images for some diseases have been well-established, there is room for improvement. Many treatment decisions are based on simplified criteria and incomplete data and our understanding behind the pathophysiology of many of these diseases remains woefully incomplete. A stronger grasp of the relationship between disease and hemodynamics can help clinicians plan better treatment outcomes or help prevent some complications from occurring./n4D-Magnetic Resonance (MR) Imaging can be a powerful tool for quantifying the flow field within the cardiovasculature, but remains difficult to integrate for clinical use due to the involving process required to convert noisy magnetic resonance image data from a set of symbols to an easily digestible image. Treatment decisions are based on standardized practices, but no standardization for the processing and interpretation of 4D-MR images exist. Computational Fluid Dynamics (CFD) can simulate patient hemodynamics with much finer temporal and spatial resolution than 4D-MR. However, computational methods must still use boundary conditions obtained from imaging data, which means CFD results can only be as accurate as the images they are based upon. Additionally, the logistics of performing CFD, which require extensive training and time, is a strong barrier against its adoption in a clinical setting./nThis thesis presents a model for using in vivo (live) and simulated flow data as complementary methods to explore potential mechanisms of pathophysiology and aid the treatment of cardiovascular diseases. We developed pipelines for processing 4D-MR images and for building patient-specific CFD simulations. We first attempted to measure the experimental error in 4D-Flow MRI within a cerebral aneurysm phantom and explored how that error might propagate into CFD results based on those MR measurements. We used those results to predict how this sensitivity would affect the treatment of aneurysms based on their hemodynamics. We then used both 4D-MR and CFD methods to characterize a rarely explored vascular territory, the cerebral venous outflow tract (CVOT). 4D-Flow MR was used to categorize geometries and flows in the CVOT. CFD was used to investigate a potential association between flow and symptoms in a subcategory of internal jugular vein geometries.

Advisor: Saloner, David
Three Essays on Chinese Population

How can we interpret the demographic behaviors in Chinese society, whose culture is quite different from the West? To what extent can these behaviors be explained with existing theoretical frameworks? Or do we need to modify these frameworks or even create new ones? To shed lights on these questions, I conducted three quantitative studies using Chinese data samples. Each study investigates a specific question. Using the Great Famine as a natural experiment, the first essay examines the causal link between education at young ages and cognitive abilities in elder life. I find that the unexpected occurrence of famine deprived millions of educational opportunities at that time, which in turn resulted in long-term consequences for mental health and cognition. The second essay also focuses on the cognitive functions of elder adults in China through a discussion about the role of political connections, measured with a dummy variable indicating whether at least one of each respondent’s children is politically employed. The empirical results confirm the beneficial effect of having a cadre child, which partially works through the channel of encouraging social interaction. In the last essay, I examine how a girl’s educational attainment is associated with her given name. The given name may reveal the expectations of parents and also affect girls’ self-aspirations. By constructing three quantitative indices for each given name based on its relative frequency in different groups, I show that girls with a more educated, urban, male-sounding name are more likely to attend junior high school.

Advisor: Lee, Ronald D
Facilitating Decision Making through Attribute Matching

Across 11 studies, the authors demonstrate a novel framing effect, attribute matching, whereby matching a salient attribute of a decision frame with that of a decision’s options facilitates decision making. This attribute matching is shown to increase decision confidence and, ultimately, consensus estimates by increasing feelings of metacognitive ease. In Study 1, participants choosing the more attractive of two faces or rejecting the less attractive face reported greater confidence in and perceived consensus around their decision. Study 2 extended this finding from valence to calorie judgments, whereas Studies 3-5 extended the effect to different post-decision attitudes. Study 6 found decision ease mediates these changes in confidence and consensus estimates. Consistent with a misattribution account, when participants were warned to this external source of ease in Study 7, the effect disappeared. Studies 8-10 rule out alternative accounts, such as response substitution and language effects. The final study demonstrates attribute matching in a more realistic context. The paper concludes with a discussion of related psychological constructs as well as potential downstream consequences.

Advisor: Nelson, Leif D.
Polarimetric Studies of the Long Duration Gamma-Ray Burst GRB 160530A with the Compton Spectrometer and Imager

Gamma-ray bursts (GRBs) are highly luminous flashes of gamma-rays that last from hundreds of milliseconds up to hundreds of seconds, peak in the soft gamma-ray band 0.1 MeV to 1 MeV, represent ultra-relativistic motion, and originate from cosmological distances. Despite thousands of observations of GRB prompt emission, and hundreds of observations of GRB afterglows, many details pertaining to the nature of gamma-ray bursts remain elusive. A wide variety of models exist that describe the progenitors, central engines, emission mechanism, geometric structure, and magnetization of GRBs. Polarization measurements of the GRB prompt emission are believed to give essential clues where spectral and temporal observations fall short./nThe Compton Spectrometer and Imager (COSI) is a balloon borne Compton polarimeter, imager, and spectrometer sensitive in the 0.2 MeV to 5 MeV band. One of COSI's main science goals is measuring the polarization of astrophysical gamma-ray sources, including GRBs. Polarimetric measurements with a Compton polarimeter are possible due to the sensitivity of the Compton scattering cross section upon the orientation of the photon's electric field vector. We verified COSI's polarimetric capabilities in the laboratory using partially polarized and unpolarized beams, and compared the measurements to simulations. Overall, the measurements reflect the simulations closely, and we were able to place upper limits on the systematic error on the polarization level of 3% - 4%./nIn May of 2016, COSI took flight from Wanaka, New Zealand aboard a NASA Super Pressure Balloon. COSI continuously telemetered science data for 46 days before landing in Southern Peru. On May 30, 2016, COSI clearly detected the long duration gamma-ray burst GRB 160530A. We performed a polarization analysis of this GRB using both a standard method (SM) and a maximum likelihood method (MLM). The measured polarization level was below the 99\% confidence minimum detectable polarization level (MDP) using both analysis methods (MDP = 72.3% +/- 0.8% for the SM, and MDP = 57.5% +/- 0.8% for the MLM), so we claim a non-detection of polarization for this GRB. Using the MLM, we placed a 90% confidence upper limit of 46% on the polarization level. GRBs with polarization levels higher than 46% have been reported in the literature, and so this result will be useful in future meta-analyses that consider the statistical distribution of polarization levels across the GRB population.

Advisor: Boggs, Steven
Enter Audience: Forms of Theatrical Spectatorship in Modernist Writing

The early twentieth century saw rapid changes in the technologies and concepts of perception, from the development of phenomenology and the emergence of film to the fracture of Renaissance perspective in painting and the avant-garde’s vitalization of simultaneity, durée and multimedia. At the center of all these innovations stood the spectator. For modernists like Marcel Proust, Wyndham Lewis, Gertrude Stein, James Joyce, and Samuel Beckett, I argue, the theater offered the paradigmatic space to articulate systems of perception, where the spectator could participate in a virtual network of formal and social relations embedded in the collective audience. My project demonstrates that the proliferation of quasi-theatrical narrative prose in the twentieth century intended to script this network of spectators into a spectacle for the reader’s gaze. Embedding theatrical forms into literary text, these authors preserved the capacity of the spectator to synthesize diverse elements into virtual systems, while they attempted to ground those systems in an audience that stood as a concrete figure for collective experience. The audience becomes a unique perceptual body and system. Indeed this emergent collective sensorium synthesizes the interaction between drama, narrative, and painting into a “virtual theater,” imagining a theatrical practice not restricted to the theater’s physical space. My dissertation, Enter Audience: Forms of Theatrical Spectatorship in Modernist Writing, argues that these perceptual systems, articulated by the modernist quasi-theatrical text, conceptualize not only the variegated ways that audience perceptions constructively and destructively interfere like propagating waves, but also how they construct the operations of social forces and proffer them to the analysis of the reader.

Advisor: Blanton, C. D.
Novel Reading: Pedagogies of Form in George Eliot and Thomas Mann

This dissertation examines the intersection of novel form and questions of education in the novels of George Eliot and Thomas Mann. While each of the novels I consider structures its plot around the formative experiences of a young protagonist, whose development thereby constitutes both the arc of the story and the stakes of the novel, I argue that their concern with pedagogy extends beyond the diegetic representation of education to the form of the novel itself, in ways that are both continuous and in tension with some of their more obvious didactic workings. These novels put forth an implicit argument for the way that a novel can itself contribute to the formation of its readers: namely, by teaching them to be readers of novels, through a novelistic practice that sees form as pedagogical and pedagogy as formal. My first chapter traces the conjunction of form, formation, and the work of the novel in both the eighteenth-century German concept of Bildung, in which I locate the network of ideas that become crucial to my reading of Eliot and Mann’s pedagogy of form, and in Christoph Martin Wieland’s Geschichte des Agathon, Jane Austen’s Northanger Abbey, and Johann Wolfgang von Goethe’s Wilhelm Meisters Lehrjahre, which I read as forerunners of the self-reflexive novelistic practice that Eliot and Mann exemplify. Chapters two and three examine the way Eliot’s formal pedagogy informs and also challenges the explicitly stated realist projects of her novels. I argue that both Felix Holt, the Radical and Middlemarch displace the type of education that they initially seem to center— the political reform espoused by the eponymous Felix and the modes of book learning valued by Middlemarch’s scholars— in favor of modes of formation that they link to the novelistic, such as the sentimental and sympathetic lessons of their female protagonists, the novels’ own plotting, and the work of recognition and interpretation that they demand of both their heroine and reader. In privileging such acts of readerly formation, the novels don’t, however, put forth a monolithic definition of novel form but instead underscore the multiple, often contradictory modalities through which their own form moves and whose different demands they teach their reader to negotiate. In turning to Thomas Mann in chapter four, I examine Der Zauberberg’s explicit commentary on form in its meditation on the possibilities of Bildung in post-World War I Europe, and I argue that the “middle” way that its protagonist espouses serves as a description of both the novel’s own form and the pedagogic practice it represents and seeks to enact. An afterword to the dissertation suggests that such a middle space becomes synonymous with a model of novel reading that grows out of this intersection of novel form and pedagogy in Eliot and Mann’s work.

Advisor: Lucey, Michael
Random Matrices and the Sum-of-Squares Hierarchy

We study the Sum-of-Squares semidefinite programming hierarchy via the lens of average-case problems./nThe Sum-of-Squares Hierarchy is a formulaic family of convex relaxations to polynomial optimization problems, which allows one to trade runtime for accuracy in a smooth manner. The Hierarchy has been studied since the early 2000’s, both from the perspective of optimization and control and as a proof system. In the past five years, the Hierarchy has become a focus of intensive study in the theory of computation community. This is because recent results give us reason to hope that Sum-of-Squares algorithms may refute important/nconjectures on hardness of approximation. However, our understanding of the guarantees of the Hierarchy remains relatively incomplete./nIn this dissertation, we present three results which make modest progress towards understanding the power and limitations of the Sum-of-Squares Hierarchy; all three works use average-case problems as a lens for the Sum-of-Squares algorithms, by enabling us to use/nrandom matrix theory as a tool in the analysis./nFirst, we analyze the performance of the Hierarchy for strongly refuting random constraint satisfaction problems (CSPs). We obtain a full characterization of the Sum-of-Squares Hierarchy for strong refutation of random CSPs, and give new subexponential-time strong/nrefutation algorithms for CSPs with super-linear density./nNext, we give impossibility results for solving the planted clique problem via a Sum-of-Squares algorithm, demonstrating that the degree-4 Sum-of-Squares algorithm cannot distinguish graphs which contain a planted clique from uniformly random graphs./nFinally, even in the asymptotically polynomial-time regime, the Sum-of-Squares algorithm is often prohibitively slow. We show that for average-case problems, polynomial-time Sum-of-Squares algorithms can often be replaced with fast spectral algorithms, which run in linear or near-linear time in the input size.

Advisor: Raghavendra, Prasad
Rao, Satish