VictorJuiz/thesis huggingface dataset:
Learning and Analyzing Representations for Meta-Learning and Control

While artificial learning agents have demonstrated impressive capabilities, these successes are typically realized in narrowly defined problems and require large amounts of labeled data. Our agents struggle to leverage what they already know to generalize to new inputs and acquire new skills quickly, abilities quite natural to humans. To learn and leverage the structure present in the world, we study data-driven abstractions of states and tasks. We begin with unsupervised state representation learning, in which the goal is to learn a compact state representation that discards irrelevant information but preserves the information needed to learn the optimal policy. Surprisingly, we find that several commonly used objectives are not guaranteed to produce sufficient representations, and demonstrate that our theoretical findings are are reflected empirically in simple visual RL domains./nNext, we turn to learning abstractions of tasks, a problem typically studied as meta-learning. Meta-learning is an approach to endow artificial agents with this capability that leverages a set of related training tasks to learn an adaptation mechanism that can be used to acquire new skills from little supervision. We adopt an inference perspective that casts meta-learning as learning probabilistic task representations, framing the problem of learning to learn as learning to infer hidden task variables from experience. Leveraging this viewpoint, we propose meta-learning algorithms for diverse applications: image segmentation, state-based robotic control, and robotic control from sensory observations. We find that an inference approach to these problems constitutes an efficient and practical choice, while also revealing deeper connections between meta-learning and other concepts in statistical learning.

Advisor: Levine, Sergey
Acculturation Strategies and Educational Outcomes of Chinese American Children of Immigrants

In this study, I examined whether Berry’s (1997) acculturation strategies would be found in a sample of 258 Chinese American adolescents who are children of immigrants (CIs) and whether these strategies were associated with educational outcomes. I conducted separate latent profile analyses (LPA) on participants’ American and Chinese orientation in each of the three behavioral acculturation domains (language proficiency, social relationships, and media use). I also conducted LPA on the composite scores of participants’ Chinese and American orientations which combined all of the domains to see whether there were differences when analyzing acculturation by domain or combined as a composite. I found six different profiles (integrated, assimilated, marginalized, moderately separated, strongly separated, and ambivalent), but they were not all represented in every acculturation domain. I found practically significant differences in GPA (i.e., Hedges’ g > 0.41), educational expectations, and perceived competence among the profiles in the three acculturation domains and the composite analysis. Generally, participants with the integrated and assimilated profiles often reported the more favorable academic achievement outcomes, and the other profiles were associated with different educational outcomes depending on the domain examined. The results demonstrate the complexity of Chinese American CIs’ acculturation processes and can inform future acculturation research on this population.

Advisor: Worrell, Frank C.
Carbon Dioxide Reduction at Organic-Metal Interfaces

Chapter 1 – The rising levels of CO2 in the atmosphere necessitate further investigation into methods of converting CO2 into more valuable products. In this chapter, we introduce the chemistry of CO2 conversion, particularly via electrocatalytic methods, and the strategies and considerations involved in selectively reducing CO2 to desirable products./nChapter 2 – We describe the effects of the CO2 reduction device on the observed product selectivity and the method used herein to evaluate the performance of metallic catalysts./nChapter 3 – We develop a predictive framework to understand how organic modifiers on a Cu surface influence the selectivity of the CO2 reduction reaction at the metallic surface. This study of a series of polymeric and molecular modifiers indicates that protic species enhance selectivity for H2, hydrophilic species enhance formic acid formation, and cationic hydrophobic species enhance CO selectivity. The relationship between these structural features of the modifiers and the changes in selectivity yields insights into how these modifiers influence catalytic behavior. We hypothesize that the hydrophilic/hydrophobic modifiers influence the binding strength of surface hydrides, which yield formic acid or H2. This study demonstrates how the selectivity of a single metallic surface may be tuned to favor formic acid or CO simply by changing the properties of the added organic modifier and may aid in the future implementation of organic structures in CO2 reduction devices./nChapter 4 – The study of cationic ammonium salts on a Ag surface allows a closer investigation of how these salts influence CO formation. The trends observed with these ammonium salts indicate that the selectivity-determining factor is not the hydrophilicity/phobicity, but rather the length of the longest hydrocarbon substituent. This correlation suggests that the ordering of the ammonium salts at the Ag surface plays a key role in obtaining improved CO selectivity. We discuss possible mechanisms by which these ordered ammonium salts may influence the formation of CO. The emergence of the organization of these organic modifiers as an important parameter demonstrates that strategic design of these modifiers requires an understanding of not only the mechanism, but also of ancillary features of the organic species that impact their ability to influence surface processes.

Advisor: Toste, F. Dean
“Comique et Laid”: Bitter Laughter and Dystopia in Francophone Caribbean and Urban Literatures

In spite of the flashy, highly consumable traits that have earned it considerable success in the last two decades, the work of literary dystopias is complex, engaging nothing less than the past, the present and the future. It is easy to forget that beyond the stunning special effects of its cinematographic productions, or the suspenseful, page-turning poetics of its literary expressions—in short, beyond its undeniable entertainment value—the dystopian genre, in its most recent iteration, aims above all to shake the world out of the dangerous complacency of late-stage capitalism. There exists a tension between the genre’s extravagant aesthetics and the latent threats it wishes to signal. Onscreen or on the page, protagonists vie for their physical lives in ostentatiously dangerous situations. These are metaphors for other, often invisible yet very real threats, including social death and cultural death are such threats. My dissertation explores specifically how authors of francophone expression seek to represent the experience of minoritized subjects by utilizing dystopian tropes that render these invisible threats visible./nI take as a point of departure that the République universelle française continues to be animated by a utopian ethos inherited from a perennial humanist tradition. Still in search of an essential, universal understanding of both Frenchness and humanity, it struggles to relate to those among its citizens whose ontological particularities resist its homogenizing impulses. In its new postcolonial iteration, France seems to envision itself as having achieved utopia: it purports to be a good place. But for those who do not comfortably fit within these ideological walls, this utopia is perceived as a dystopia: a bad place. To be sure, it is a soft dystopia, one that operates on lower frequencies, which allows it to continue to pass as a utopia. My dissertation contends that the presence of dystopian tropes in the literary and cinematographic works I explore exposes the République universelle française for what it is. Fictional dystopia emerges out of and unmasks its real-word, underhanded alter ego./nThe frequent presence of laughter alongside these dystopian tropes is striking, and calls for close consideration. How can one laugh in the face of cultural death? What is the function of this laughter? Does it serve to soften the moral indictment of the Republic? Does it serve to render the critique more vitriolic, tipping it toward the satirical? Does it constitute a self-soothing gesture for the writer or the artiste? Can this laughter also be complicit? Can it be the sign of the surrender of the self to the powerful appeal of utopia? The search for answers to these questions has brought the present work to the intersection of postcolonial critique, utopian/dystopian studies and laughter theory.

Advisor: Britto, Karl A.
Peace Agreements as Counterinsurgency

Peace agreements are heralded as tools for ending civil war. However, exclusive peace agreements, accords that include only a subset of a conflict's warring parties, are unlikely to bring an end to a civil conflict. I argue that exclusive peace agreements serve a purpose beyond conflict resolution. Exclusive peace agreements are a counterinsurgency strategy./nCombatting more than one rebel group strains governments’ military abilities by dividing resources across multiple wars. Governments that would otherwise be able to defeat a rebel group may be unable to do so when tied down by multiple insurgencies. Based on this logic, and in contrast to the literature on spoilers in peace processes, I argue that the threat posed by other insurgent groups increases the likelihood that a government and rebel group sign an exclusive negotiated settlement. Exclusive peace agreements allow governments to consolidate military resources into the fight against the remaining insurgency. Exclusive peace agreements can further strengthen a government's counterinsurgency capabilities by including provisions for military power-sharing that transform conflict adversaries into war-fighting allies./nTo test this hypothesis, I analyze all multiparty civil wars from 1975-2013. In support of the theory, I find that the threat posed by other rebel groups is positively correlated with the likelihood that a government and rebel group sign an exclusive peace accord. I then use a case study of civil war in the Southern Philippines to bring to light the mechanisms that undergird these correlations. In line with the theory, the threat posed by other rebel groups jump-started stalled peace talks with Moro insurgent groups. I also find that exclusive peace agreements were successful mechanisms for incorporating rebel soldiers into the government's fight against other rebel groups.

Advisor: Mattes, Michaela
Cosmic Cartography: Mapping the Universe for Next-Generation Dark Energy Voyages

Mapping the distribution of matter and light in the Universe is key to unlocking some of its most fundamental secrets. What drives the acceleration of cosmic expansion? Does Einstein's Theory of General Relativity fail on very large scales, requiring a new model of gravity to account for an accelerating expansion? Or is there some exotic and invisible form of "dark energy" that dominates the composition of our Universe? Beginning with the Dark Energy Spectroscopic Instrument (DESI), a series of next-generation galaxy surveys will revolutionize our understanding of dark energy, providing an unprecedented wealth of data to solve these and other cosmic mysteries. Several major challenges directly determine the ultimate success of ambitious missions such as DESI: how tightly systematic sources of error and contamination can be controlled, how well the biases and properties of the galaxy samples can be understood, and how accurately their positions can be mapped. This thesis presents contributions I have made towards addressing these challenges and doing early science with DESI, for which I received "Builder Status" by the DESI Collaboration. Approximately two-thirds of this thesis are devoted to performing the first major analysis of the systematics and clustering of DESI samples selected from deep imaging. In the final part of this thesis, I present a cross-correlation between DESI galaxies and the lensing of the cosmic microwave background, one of the most significant detections of this type of signal to date, from which I further characterize the DESI samples and also study how the accuracy of their positions impacts science goals. In addition to enabling future cosmology with DESI, the methodologies and frameworks developed in this thesis have broader applications in future dark energy experiments and, more generally, cosmological studies using deep imaging data.

Advisor: White, Martin J
Design, Fabrication, and Characterization of a High-Frequency Microwave Cavity for HAYSTAC

The nature of dark matter is one of the most outstanding mysteries in science today. Possibilities for its composition range from black holes to heavy particles that can be detected by their collisions with atomic nuclei to light particles that act like a coherent field. Sensitive experiments have not yet been able to detect dark matter. A case can be made that the most promising dark matter candidate is the axion, which was invented to solve the strong charge-parity problem in the standard model of particle physics. If the axion exists, it could be produced in abundance and constitute a major component of dark matter./nIn the presence of a magnetic field, axions will be converted to an oscillating electromagnetic field with a frequency approximately corresponding to the axion mass. We can detect this electromagnetic field as a power excess spectrally coincident with the resonance of a microwave cavity. Each microwave cavity can provide good sensitivity in the search for axions over a limited frequency range, but we must consider new technologies to probe the full axion parameter space in a reasonable amount of time. Both as a testbed for innovative cavity and amplifier concepts and as a data pathfinder for higher frequencies, the Haloscope at Yale Sensitive to Axion Cold dark matter (HAYSTAC) was the first cavity experiment to use a dilution refrigerator and commission a squeezed-state receiver to circumvent the Standard Quantum Limit. The HAYSTAC Phase I and II cavity is a cylinder with an internal rod that rotates off-center and tunes the mode-of-interest resonance frequency between 3.4 and 5.8 GHz in a volume of 1.5 L. Recent theoretical work favors axions between 4 and 12 GHz./nI examined various cavity designs to access higher frequencies in this range and determined that a seven-rod cavity design would be optimal with a volume of 1.7 L for a frequency range between approximately 5.5 and 7.5 GHz. I designed this seven-rod cavity, constructed it, and characterized it in detail for use on HAYSTAC. My cavity design allows access to this well-motivated axion mass range with high sensitivity by increasing accessible frequencies without sacrificing performance. This seven-rod concept can be extended to higher frequencies.

Advisor: van Bibber, Karl A
Philosophy and Methodology of Psychological Measurement for Social-Emotional Skills

Operationalism, representationalism, and pragmatism are three major philosophies of measurement in psychology and education. These philosophies play important roles in designing and conducting measurements, as well as interpreting results. When measurement results are available, validity evidence plays important roles in supporting the plausibility of interpretation of measurement results and the appropriateness of use of measurement results. This paper focuses on discussing the nature and concepts of the philosophies and validity. Having this done, an integrative framework is described, called the construct modeling approach, in which the three philosophies and validity are situated to serve the complex reality in the fields. The assessment of Thai community attachment (TCA) is used to demonstrate how the framework works./nThe assessment began with creating a developmental structure of community attachment, called the TCA construct map, to show five levels of the attribute, ranging from Receiving as the lowest level, to Complying, Accepting, Valuing, then Expanding as the highest level. Community attachment in Thai society can be described into three content domains, including (a) National, Religion, and King (NRK), (b) Thainess, and (c) Thai Citizenship. This yielded a three-dimensional structure of community attachment. Then, the developmental structure was situated in the three dimensions; that is, three construct maps of community attachment were developed—the NRK, Thainess, and Thai Citizenship construct maps./nSituational TCA items were created and assigned to grade 9th students in Thailand. Student scores or measurement results were intensively investigated in order to provide validity evidence to support the plausibility of score interpretation and the appropriateness of score use.The results showed that when the construct modeling approach was used as the integrative framework, a well-designed measurement can be systematically established, and that measurement procedure empirically relates to the three underlying philosophies as well as its measurement results are supported with several validity evidence. Moreover, the integrative framework also provides useful information for the revision of the TCA assessment.

Advisor: Wilson, Mark
Electronic transport in atomically precise graphene nanoribbons

Advancements in on-surface materials synthesis have led to the development of atomically precise graphene nanoribbons (GNRs). Bottom-up synthesized GNRs have promising electronic properties for high performance field effect transistors (FETs) and ultra-low power devices such as tunneling FETs. However, the short length, wide band gap, and random orientation of GNRs have impeded the fabrication of devices with the expected performance and switching behavior. In this dissertation, progress towards integration of bottom-up synthesized GNRs into electronic devices is presented. The understanding of GNR growth and band structure is surveyed and analyzed with a focus on the implications on device yield and performance. The development of a device fabrication strategy for on-surface synthesized materials is shown, with a focus on the fabrication of high on-current and high on-off ratio 9-atom wide GNR FETs. Furthermore, device fabrication is developed for FETs with parallel arrays of GNRs transferred from single crystal Au(788), which greatly improves device yield. Finally, theoretical charge transport in GNR heterostructures is employed to demonstrate exotic device behavior such as ultra-sharp switching and negative differential resistance. The path towards state-of-the-art GNR-based logic circuits is charted in this work.

Advisor: Bokor, Jeffrey
Computational Models of Learning and Hierarchy

The aim of this thesis is to create precise computational models of how humans create and use hierarchical representations when solving complex problems. In the process, the thesis aims to understand human learning more generally, and investigates the method of computational modeling itself. The main result of the thesis is that hierarchical reinforcement learning --the layering of multiple reinforcement-learning processes at different levels of abstraction-- provides a precise and comprehensive model of human behavior in complex tasks, and has the promise to explain how hierarchical representation can be created when interacting with a problem. Our investigation of human learning shows that learning proceeds differently at different ages, and suggests that different stages of life might be optimized to solve different problems. Our investigation of computational modeling reveals that even though computational models are powerful tools for compressing complex datasets into a small number of model parameters, these parameters are not generic and task-independent, as commonly believed. Instead, model parameters should be interpreted as maximally-compact behavioral measures that are fundamentally tied to task context.

Advisor: Collins, Anne GE
Political Spirituality and the Idea of México: From the Bourbon Reforms in New Spain to Mexican Independence (1740-1821)

This dissertation investigates how discourses and practices of political spirituality contributed to forming an idea of México as a national entity in the early nineteenth century. During the struggles for Novohispanic Independence from 1810 to 1821, there was little consensus on what the new nation would be named. Writers, historians, and political figures used names such as “Anáhuac,” “América,” “la América Mexicana,” and “El Imperio Mexicano,” each conveying different political ambitions. The dissertation tracks the emergence of the idea of ‘México’ in texts produced during the era of the Bourbon Reforms in New Spain and the period of the Novohispanic insurgency. Against the analysis of the prominent symbols and cultural tropes pertaining to México as mythical or ideological construct, I argue instead for the centrality of political spirituality, which in my account designates the means of finding novel ways of governing oneself and others and discerning different ways of articulating what is true or false. Political spirituality, I argue further, enabled the emergence of new subject formations such as the ‘Americano’ insurgent and of the independent ‘Mexicano.’ Along with forming subjects, political spiritualities subtended the transformations of concepts that would allow those subjects to recognize and affirm the idea of México./nThis interdisciplinary inquiry brings together studies of political history, religion, the history of ideas, and philosophical anthropology. Approaching the emergence of the idea of Mexico through the lens of political spirituality allows me to draw on contemporary theories of the proper name and the concept as a way to tie spiritual practices to material conditions, discursive frameworks, and practical exigencies. This project contributes to a body of historical scholarship on the role of religion and religious discourse in the emergence of the Mexican nation and state. By exploring spirituality as a practice that is not intrinsically religious, this project seeks to shed light on different ways in which spiritual discourses and practices produce material effects. The dissertation represents an initial step toward a fuller genealogy of the idea of Mexico, its potentialities, promises, and limitations.

Advisor: Esmeir, Samera