VictorJuiz/thesis huggingface dataset:
Atom-interferometric test of the equivalence principle and observation of a quantum system in curved spacetime
Keywords: Physics.

The theory of general relativity is based on the equivalence principle, which states that all gravitational effects vanish in any local measurement. This principle is the best-understood aspect of gravity and has been tested with high precision in classical experiments. However, there is no widely-accepted quantum theory of gravity, and the nature of the relationship between gravity and quantum mechanics is one of the most significant open problems in physics. We study the interaction of gravity with quantum systems in a light-pulse atom interferometer, which uses lasers to measure atomic positions and accelerations. The sensitivity of the interferometer is increased by utilizing large-momentum-transfer pulse sequences and a free-fall time of up to 2 s, made possible by the 10 m scale of the apparatus. The frequencies and angles of each interferometer pulse are optimized to suppress kinematic phase gradients by several orders of magnitude. We use this system to test the equivalence principle between 85Rb and 87Rb, finding no violation at the level of 10^-12 g. With a resolution of up to 1.4 x 10^-11 per shot, we demonstrate the highest relative acceleration sensitivity yet obtained in a laboratory setting. In addition, by operating the interferometer in a gradiometer configuration, we perform the first observation of a single quantum system in curved spacetime. Finally, we propose an experiment to observe gravitational time dilation with an atom interferometer
Attending to all we elicit : student skepticism of dialogic practices and stances
Keywords: Education.

The way teachers organize classroom talk matters for the way students make sense of texts. Dialogic teaching (Alexander, 2004), a pedagogical approach that centers on student talk and sensemaking, represents a promising, albeit rare (Nystrand, 1997), alternative to instruction that is dominated by the teacher's voice. Beyond a few exceptions (Christoph & Nystrand, 2001; Aukerman et al., 2008), studies rarely offer detailed accounts of how teachers negotiate dialogic relationships with students. This dissertation offers one such account, documenting how I, as a practitioner- researcher (Cochran-Smith & Lytle, 1993), enacted dialogic teaching with a group of seventh graders in a series of small-group text discussions. In my first findings chapter, I explore how students' contestation of my revoicings (O'Connor & Michaels, 1993) challenged pre-conceived notions of how dialogic talk moves function with students. My second findings chapter focused on how students responded to one another's claims to be textual authorities (Aukerman, 2007). My findings suggest that dialogic teaching not only involves responding to the highly contingent nature of students' textual interpretations, but also to their interpretations of the relational aspects of this teaching, particularly the power imbued in these relationships. It also suggests that student criticality is not always text-centric, but can be directed at the pedagogical context - and is sometimes voiced in-the-moment of instruction. Thirdly, my findings suggest that student criticality was not the sole possession of individual students, but was something that emerged in dialogue, a collective critical awareness of how my dialogic pedagogy was sought to position students
An automatic feeding system for the African killifish reveals effects of dietrary restriction on lifespan and allows automatic assessment of reward-based learning behavior
Keywords: Biology.

The African turquoise killifish, Nothobranchius furzeri, is an exciting new vertebrate model for aging studies. However, a significant challenge for any new model is control over its diet in space and time. To overcome this issue, I created an automated and networked fish feeding system. This system is designed to be transferable, open-source, and built from widely-available components. Compared to manual feeding, this automated feeding system is considerably more precise and flexible. As a proof-of-concept for the feeding schedule flexibility of these automated feeders, I defined an optimal feeding regimen for growth and fertility for the African killifish, which I call "ad libitum" feeding, and a dietary restriction regimen where both feeding timing and quantity are reduced. I show that this ad libitum feeding regimen significantly increases growth in males and fertility in male/female pairs as compared to dietary restriction. However, I show that an overfeeding regimen which I also define increases growth while decreasing fertility compared to ad libitum feeding. I showed that the defined dietary restriction regimen robustly extends lifespan when compared to ad libitum feeding in males but not in females. I fit a Gompertz distribution to the survival curves of males fed either an ad libitum diet or a dietary restricted regimen and find that lifespan extension by dietary restriction results in a significant reduction in the "Rate of Aging" parameter. Combining this automatic feeding system with a video camera also allowed me to create an associative conditioning assay, which I validated using manual scoring. I then proceeded to implement an automatic scoring pipeline which allows for a high-throughput integrative measure of fitness and agrees with the manual scoring approach. The ability to precisely control feeding in the killifish opens new areas to explore lifespan dynamics, dietary interventions, drug delivery, and behavior in a high-throughput manner previously impossible with traditional vertebrate aging model organisms
Autonomy, intimacy, and the law
Keywords: Political Science.

Inspired by the "Me Too" movement in the end of the second decade of the 21st century, this dissertation is an attempt to articulate a grounding theory for the value of human sexuality through the lens of personal autonomy. It derives a concept of "sexual autonomy" from the value of sex and sexuality in human life and argues that autonomy grounds the value of intimate expression and provides a framework for its proper regulation. As a foundational value, autonomy underpins and explains the notion of "consent", which defines contemporary understandings of sexual assault. The first two chapters of this dissertation develop the connection between the value of sexuality in human life, with the notion of sexual autonomy as a version of personal autonomy. Subsequent chapters examine the practical implications of this understanding of sexual autonomy for legal and social reform of the regulation of the sexual sphere
Auto-play : the automation of performance action, writing, and control
Keywords: Theater and Performance Studies.

This dissertation discusses a series of artists who, throughout the twentieth and early twenty-first centuries, have attempted to automate theatrical processes. Offering a model of "automaticity" as disintermediation and opacity, encompassing the traditions of both automatism and automation, I argue that thinkers of the theater have long juxtaposed automaticity with theatricality. However, as my case studies demonstrate, the automatic and the theatrical can indeed be integrated. Abstract action has been mechanized, dances have been computationally scored, and backstage control has been automated. I analyze performance practices of artists from the avant-garde canon, from experimental margins, and from the commercial mainstream: central figures include Raymond Roussel, László Moholy-Nagy, Jeanne Beaman, Analívia Cordeiro, Frederick Bentham, and Robert Wilson. Throughout, I explore the liberal and neoliberal politics of automaticity, consider the images of femininity and blackness attached to the automatic, and conclude that the conjunction of automaticity and theatricality is dominant within contemporary stage practice and social relations
Avian-inspired rudderless flight with morphing wings and tails
Keywords: Mechanical Engineering.

Winged aircraft typically have vertical tails and rudders for directional stability and control, but removing these vertical tails could enable flight performance improvements through weight and drag reduction. Previous approaches to rudderless flight have compromised drag, weight, or maneuverability. In contrast, birds can articulate and morph their wings and tails, continuously adjusting aerodynamic geometry for unparalleled flight performance, all with no vertical tail surface. We explore mechanisms for rudderless bird flight in two flight regimes: flapping and gliding, which are vastly unique in their aerodynamics. For flapping flight, we developed a wind tunnel study that measured the passive yaw dynamics of small ornithopters, inspired by birds that navigate 45 degree crosswinds with ease. Our results demonstrate a passive yaw sideslip suppression mechanism available to flapping wings for the first time, which can be sufficient as a flapping wing vehicle's only static directional stability mechanism for yaw stability. For gliding flight at lower angles of attack, however, birds must use a different strategy. To study how wing and tail morphing may be used for rudderless bird flight, we developed a new class of soft feathered aerial robots that underactuate feathers to generate biomimetic bird wing and tail morphing. Our experiments and analysis show how the underactuation mechanism used in these vehicles are remarkably high-bandwidth and aeroelastically stable. Through wind tunnel and flight tests, we demonstrate how birds can use finger motion to steer precisely, or wrist motion to steer coarsely in flight. We also found that without a vertical tail, many bird planforms are dynamically unstable but can use lateral tail tilt to stabilize yaw rates for stable flight. We culminate this research with a comprehensive morphing wing and tail robot composed of 52 feathers underactuated by 8 active degrees of freedom, and use it to show how birds can synergize their wing and tail morphing degrees of freedom to achieve robust flight in turbulence and aggressive maneuvers, all with inexpensive and relatively low performance actuators. We envision this work to inspire future aerial robot designs that are more stable, efficient, and maneuverable, all while remaining simple to actuate and control
Barometer falling : weather, risk, and the meteorological imagination in Bangladesh
Keywords: Anthropology.

Given its topography and deltaic landscape, Bangladesh has long been characterized as uniquely susceptible to climate change. But this vision of Bangladesh's population and landscape being particularly vulnerable to the ravages of climate is, paradoxically, nothing new. Weather-borne ecological disasters are historically recurrent hazards. Heralded as a "laboratory for development, " Bangladesh and its precursors, East Pakistan and East Bengal, were subject to massive landscape interventions in the coastal zone as colonial and postcolonial regimes attempted to control riverine incursion into villages. State attempts to manage weather and reorganize terrain have consistently catalyzed other vulnerabilities. Through multi-sited ethnographic fieldwork with state meteorologists and with multi-religious and multi-caste farming communities, this dissertation analyzes the modes by which Bangladeshis make sense of changing ecologies. I highlight the tensions between the environment, conceived of broadly, and various attempts to govern it. This dissertation explores the intersection of climate change as a newly emergent form of risk, against a dense history of dealing with multiple forms of risk, ecological and otherwise. By examining the consolidation of the Indian Meteorological Department in Calcutta in the 1860s and 70s, contemporary practices of forecasting at the Bangladesh Meteorological Department, the implementation and unraveling of development projects in southwest Bangladesh, and the way rural residents utilize networks of gossip and collective speculation, I show that the negotiation of risks coheres together the social across my field sites. This dissertation concludes with a discussion of what I call the meteorological imagination
Bayesian structural learning in decision analysis
Keywords: Management Science and Engineering.

This work presents a method of using data to facilitate the creation of influence diagrams as part of model generation. The problem that motivates this dissertation is a bottom-up modeling approach of Decision Analysis that uses expert interviews to define variables, distinctions and capture the relations between the variables that reflect the current state of information about the decision situation. Creation and parameterization of the model defined in such way is a lengthy and error-prone process that poses a significant challenge in real-life applications. The proposed method of using Bayesian Structural Learning assumes the presence of some prior data on the problem and bootstraps relevance diagrams from such dataset. This novel approach assumes a structured coordination between machine learning methods and human experts, and in return offers extended opportunities in model generation while avoiding the common pitfalls stemming from the difficulties of eliciting conditional probabilities. We demonstrate the workings of this method using synthetic and real-life examples, and describe how to take full advantage of artificial intelligence algorithms -- including unsupervised learning with neural networks -- to facilitate work in the decision modeling phase
Bd in the Bay Area: Characterizing Batrachochytrium dendrobatidis Prevalence in Anurans by Physiology, Climate, and Local Environment
Keywords: Batrachochytrium dendrobatidis
chytridiomycosis
anurans
Bay Area
California
frogs
habitat
environment
Rana draytonii
Earth Systems
Thesis

Batrachochytrium dendrobatidis (Bd) is a parasitic waterborne fungus that has recently decimated frog populations worldwide. This Bd-induced loss of frogs has caused harm to both human and natural systems, and is considered a top priority within conservation science. However, the dynamics of Bd are still not fully understood, especially in different geographies and climates. The proportion of frogs infected with Bd –known as the infection prevalence– can vary by physiology, season, and habitat, even within a given region. One ecologically important location where frog Bd prevalence is still unknown is the San Francisco Bay Area. In this honors thesis, I begin to characterize Bd infection prevalence in the Bay Area’s frogs by exploring how the proportion of frogs infected differs by species, sex, age, body condition, month, and habitat type. The diversity of environments across Stanford University-owned lands serve as the focal region of this study. From 2013 to 2019, frogs across this region were captured and non-invasively tested to diagnose infection. My results suggest that the overall Bd infection prevalence is 21.7% within these Bay Area frogs. Among the five species studied, vulnerable Rana draytonii had the lowest infection prevalence (9.62%). Surprisingly, the invasive species Lithobates catesbeianus, known elsewhere to readily contract Bd, also had a low infection prevalence relative to other species studied. Bd-positive frogs exhibited lower mass to body length ratio, a proxy for general health, than their Bd-negative counterparts. When grouped by life stage, tadpoles were least often infected by Bd, with a prevalence of just 1.49%. When comparing habitat type, the lowest infection prevalence was in undeveloped pools (3.64%), followed by semi-urban creeks. Dammed reservoirs demonstrated the highest infection prevalence (69.23%) followed by highly developed ponds and ditches, but were not statistically significant. These findings lay the groundwork for further study and have the potential to inform targeted conservation efforts for the Bay Area’s at-risk species.
Behavior of metastable nanomaterials
Keywords: Materials Science and Engineering.

The interplay between structure and function is a central pillar of materials science. Developing and understanding methods for manufacturing new materials is key to engineering devices with desired performance. In this thesis, we explore the control of surface properties in nonequilibrium shapes and phases of metallic nanomaterials. First, we look at a simple system of copper nanoparticles. Here we demonstrate a schema for varying the shape of particles in inert gas condensation. We report one of the first syntheses of (100) face-centered cubic nanocubes made through this vapor phase method and show through both experiment and molecular dynamics modeling that shape is primarily modulated by atomic deposition rate. In the second part of the thesis we move away from the simple copper case and look at mixing two components to engineer functionality. Silver is a cheaper, more earth-abundant alternate to platinum for catalyzing the alkaline oxygen reduction reaction; however, its performance is still lagging. We show that by mixing silver and copper together, we can obtain a thin film catalyst whose activity is greater than the sum of its parts for Cu-rich compositions. In this work, we leverage x-ray diffraction and x-ray absorption spectroscopy to study the phase behavior of this Cu-Ag bimetallic system. We show that these catalysts are two-phase materials with increased metastable solid solubility in the constituent phases, from which the minority, Ag-rich phase provides the enhanced activity
Beyond the test score : the role of attendance and social-emotional learning in education
Keywords: Education.

Non-cognitive skills, or skills not measurable using standardized assessments, are important for student success and predictive of short- and long run outcomes. This dissertation is comprised of three papers examining the role of two non-cognitive skills in education: student attendance and social-emotional learning skills. The first paper examines the negative effects of secondary school student absences on short- and long-run outcomes. The second paper reports the results of a randomized experiment incentivizing student attendance in secondary schools. The third paper examines changes in student social-emotional skills due to English Learner reclassification using a regression discontinuity analysis. Results imply that absences are risky behaviors that have dynamic effects in the short and long run; symbolic awards for attendance can send the wrong signals, backfire and demotivate the target behavior; and reclassification into mainstream learning settings is an effective way to improve academic confidence among former English Learners. Evidence from this dissertation may inform readers of the significance of non-cognitive skills in schooling, as both inputs and outputs in the educational production function
Biodiversity monitoring, earth observations and the ecology of scale
Keywords: Biology.

Climate change, agricultural expansion, and population growth are dramatically altering ecosystem structure, function, and community composition worldwide. Yet our ability to measure, monitor, and forecast biodiversity change—crucial for mitigating it—remains limited. Until recently, global biodiversity monitoring systems seemed far-fetched. The sheer amount of data that would be required to map the variation in genes, species, communities, and ecosystems that comprises biodiversity is enormous, to say nothing of mapping change over time. Until recently, ecology was perceived as a data-scarce discipline, with field plots and species occurrence records sparsely and opportunistically collected, and access fragmented among research groups. But several advances in the past decade—the deployment of hundreds of earth observing sensors, the consolidation and standardization of open ecological data, and increased access to open software and computing resources—have significantly reduced the ecological data gap that biodiversity monitoring systems needed to bridge. What should we make of all this new information? Right now, the data alone are insufficient for monitoring purposes. Ecological data are subject to taxonomic, geographical, or recency biases, and satellites do not record measurements in ecological units; they're often in units of energy. But a framework that links these disparate data types—discrete, spatially-explicit species data and continuous, feature-rich, and regularly-updated earth observations imagery—could be used to precisely map species locations and habitat across large extents over time. In this dissertation, I demonstrate how concepts of pattern and scale in ecology could be used to design such a framework, as these concepts apply to both ecological and to earth observations analyses. Following a literature review of the scale-dependent challenges to linking field and earth observations data, I describe two scale-explicit machine learning approaches to species mapping: classifying species identities for individual tree crowns in high resolution airborne earth observations data, and mapping the niches and distributions of two mosquito arbovirus vectors, Aedes aegypti and Ae. albopictus, using low resolution satellite data. The tree species modeling approach identified crowns with $> 90\%$ accuracy, enabling precision species mapping over large areas. The mosquito modeling approach identified novel drivers of the spatial distributions for these arbovirus vectors, revealing that resource constraints (i.e., access to blood meals) play a central role in determining distribution patterns for these globally invasive species. These applications span several orders of biological magnitude, mapping some of the largest (trees) and smallest (mosquitoes) terrestrial macro-organisms across landscape and continental extents. This work advances the conceptual and technical basis for deploying satellite-based biodiversity monitoring systems using ecological scaling principles