VictorJuiz/thesis huggingface dataset:
Large-eddy simulation of span-periodic and three-dimensional shock/turbulent boundary layer interactions [electronic resource]
Keywords: Aeronautics and Astronautics.

Shock-turbulent boundary layer interaction (STBLI) remains a critical phenomena in the design and performance of supersonic and hypersonic vehicles. This investigation utilizes high-fidelity large-eddy simulation (LES) to better understand the physics involved in compression ramp STBLI. Specifically, streamwise oriented counter-rotating vortices in the recovery region and low frequency unsteadiness of the shock are explored in detail. A parametric variation on ramp angle is performed to explore the behavior of STBLI at a wide range of interaction strengths. An assessment of wall-modeled LES using a simple equilibrium wall-model for compression ramp STBLI at high Reynolds number is performed and deficiencies in the model are explored in detail. A first-of-its-kind LES calculation of a compression ramp STBLI with flow confining aerodynamic fences is performed to explore the three-dimensional aspects of this configuration including changes in the low frequency unsteadiness near the fences.
Laser field control of 1,3-cyclohexadiene isomerization [electronic resource]
Keywords: Physics.

Conical Intersections play a crucial role in quantum molecular dynamics, especially in polyatomic molecules where they are ubiquitous due to large degrees of freedom. We have explored the effects of light fields on conical intersections and multidimensional nonadiabatic dynamics in 1,3-cyclohexadiene (CHD). These experiments have demonstrated control of the photoinduced isomerization dynamics of CHD to 1,3,5-hexatriene in the presence of an ultrafast laser pulse. We have found that the laser field maximally suppresses isomerization if it is both polarized parallel to the excitation dipole and present 50 fs after the initial photoabsorption, at the time when the system is expected to be in the vicinity of a conical intersection that mediates this structural transition. A modified ab initio multiple spawning method was developed that showed that the laser induces a resonant coupling between the excited state and the ground state, i.e., a light-induced conical intersection. These calculations explain both the optimal timing of the control, and the photochemical process behind it.
Learning Belonging in the Classroom: The Experience of Mexican-Heritage Students in California's Central Valley
Keywords:  Department of Anthropology
Anthropology
education
language
Spanish
cultural citizenship
belonging
Thesis

This paper is the result of a research project that explores how a sample of Mexican-heritage students situated themselves in the dual language program at a California public elementary school, in which students received roughly half their daily instruction in English and the other half in Spanish. These 48 students were part of a student body in which more than 95% of students were Latino and 100% of students were considered “socioeconomically disadvantaged” by the state. Close ethnographic study through classroom observation, interaction with students, and staff interviews illuminate how students experienced finding a sense of belonging (or not) at school, with emphasis on two areas of their background: beliefs regarding the role of parents in the education experience and language use. Spanish-speaking students generally formed relationships with peers who shared the same primary language. Although the school as an institution and the staff as representatives of the school vocalized support of family involvement and Spanish as an academic or public language, day-to-day interactions did not necessarily guarantee that this message or standard of belonging was upheld. Rather, it was in connections with peers of similar backgrounds that students found acceptance. This belonging is situated in the context of a broader cultural citizenship, and implications for the individual extend to future negative social or economic effects of students not having their "right to belong" upheld by a public institution that represents the dominant national community.
Legislation and anticipation: Consequences for the measurement of the minimum wage employment effect
Keywords:  Department of Economics
Stanford Department of Economics
minimum wage
legislation
employment
lead effects
teenagers
Thesis

When Congress or a state legislature passes a minimum wage increase, there is often a period of several months between the passage of the increase and its implementation. During this period, employers know the level of the current binding minimum wage, but they also know the level of the minimum wage at a defined future date. Although this “future wage,” as I call it, is not yet binding, employers may take action to decrease their employment in anticipation of the coming increase. Using monthly CPS data from California, Oregon and Washington in the years 1994- 2014, I estimate the effect of both the current minimum wage and the future wage, when it exists, on the teen employment-population ratio. I divide the observations into two regimes: a “limbo” period during which there is a future wage, and a “normal” period during which there is not. I find that while a strong correlation exists between the minimum wage and teen employment in the normal regime, this correlation disappears in the limbo regime when a future wage exists. This indicates that although employers make employment decisions based on the current wage when no future wage exists, it is not clear whether they continue to do so when a future wage is present.
Leveraging socioemotional goals to increase physical activity in older adults [electronic resource]
Keywords: Psychology.

Physical inactivity is prevalent among Americans, particularly in older citizens, so much so that it poses a major threat to public health. My research examined two potential reasons for low levels of activity in older adults grounded in motivation: first, older adults may be inactive because they do not accrue benefits in valued domains, and second, interventions may be ineffective because they do not align with older adults' goals. Reasoning from socioemotional selectivity theory, I predicted that older adults would be motivated to engage in physical activity to the extent that it was perceived and experienced as an emotionally meaningful or satisfying activity. I posited that if older adults do not experience meaningful benefits from physical activity in the short-term, they are unlikely to maintain physical activity. To examine this possibility, I designed Studies 1 and 2 to test how physical activity influences emotional experience and cognitive performance in younger and older adults, first in a controlled, experimental setting (Study 1), then in daily life (Study 2). Findings from both studies suggest that older and younger adults experience comparably potent benefits from physical activity. I reasoned from these findings that experiencing benefits from physical activity could support maintenance of physical activity in older adults, and, therefore, initiation of physical activity, rather than maintenance, may be a key barrier to increasing physical activity in older adults. Because interventions aimed at initiating physical activity have met with limited success, particularly in older adults, the second aim of this research was to test whether interventions could be tailored to motivate younger and older adults to be more active. In Studies 3 and 4, I approached this question using values affirmation (Study 3) and an incentives framework (Study 4), in order to test the effects of reducing threat surrounding physical activity participation through socioemotional goals, and the efficacy of incentivizing physical activity through socioemotional goals. Findings from Study 3 indicated that older and younger adults responded positively and comparably to an intervention that emphasized personal values to promote physical activity. Similarly, findings from Study 4 indicated that older adults were comparably responsive to goal-based incentives as younger adults, although, once initiated, older adults better maintained the increase in physical activity relative to younger adults. Together, findings from these four studies suggest that older adults may benefit from goals-based interventions aimed at promoting and maintaining physical activity.
Libidinal engineers [electronic resource] : three studies in cybernetics and its discontents
Keywords: Art and Art History.

Libidinal Engineers offers a cultural history of automatic control in North American avant-garde media cultures of the Cold War. It tells the story of how three artists worked through the implications of Cold War "closed world" discourses of control and communication, their disastrous application in the "technowar" in Vietnam, and in the lived condition of "control societies." The dissertation follows this trajectory by means of three dilating rings: from instruments to delimited environments to lived conditions. First, I examine an instrument of automatic control, the Camera Activating Machine in Michael Snow's now-canonical La région centrale (1971) and its heretofore unknown relation to discourses of Cold War surveillance, in particular technologies of the Early Warning Line and anxieties of representation. Second, I address a delimited environment of multimedia assemblage, Carolee Schneemann's Meat System 1: Electronic Activation Room (1970), and how it appropriated both the discourse and devices of automatic control, such as human intrusion detectors, as a means to foreground issues of sexuality and gender immanent to media cultures of the Vietnam War. Finally, I introduce an examination of the lived conditions of technocratic determination, formulated in Tom Sherman's performance Hyperventilation (1970) and his construction of the part-instruments, part-sculptures Orgone Energy Accumulator (1972) and Faraday Cage (1972), where Sherman explores the darker side of American counterculture's techno-utopia and the coextensive character of control and communication on terms of not only cybernetics but a longer history of discourses of mind control. Based in new, in-depth archival research, I examine the interrelation of technologies and discourses of national defense and artistic experiments in film, video, and multimedia design. Emphasis is placed on terms of desire and affect. I focus especially on cybernetics, defined as "control and communication in the human and machine, " a discourse originating in the defense industries of World War II and scientific research in fields of physics, mathematics, and engineering. Drawing upon primary sources such as patent records, declassified wartime reports, and operating manuals, I assert artists' engagement with the mechanical basis of cybernetics in mechanical and electrical engineering, insisting upon a necessary shift from the prevailing focus upon metaphors of feedback to the hardware by which feedback was materially constituted: servomechanisms, the technology of automatic control.
Life cycle design of polypropylene fiber reinforced cement-based composites [electronic resource]
Keywords: Civil and Environmental Engineering.

Fiber reinforcement is now used for concrete applications globally to reduce shrinkage and temperature cracking, control crack widths, and provide structural reinforcement. A number of fiber types are used which include metallic fibers, polymeric fibers, and natural fibers. Of the natural fibers, asbestos fibers are used in developing countries due to their low cost and high strength as a reinforcement material in a cementitious matrix. However, asbestos has documented human health impacts which can be severe in developing countries. Polypropylene (PP) is a thermoplastic polymer that has found wide adoption for concrete fiber reinforcement. Its use has been for control of shrinkage and temperature cracking rather than as structural reinforcement of fiber reinforced concrete (FRC) due to its low bond strength in cementitious matrices. The hydrophobic nature of PP leads to low chemical bonding between fibers and the surrounding cementitious matrix. Polarity control through additive copolymerization shows substantive promise in modifying the hydrophobicity of PP to be more hydrophilic. Leveraging this hydrophilic nature, modified PP fibers can be used to structurally reinforce cementitious matrices through formation of a stronger bond with the surrounding cementitious matrix. This thesis presents a novel material design methodology which leverages multi-scale modelling and experimental testing to develop a more sustainable replacement for asbestos fiber cement roofing tiles in developing countries. At micron-scale, single fiber pullout tests are used to determine the chemical and frictional bond strength of untreated and treated PP fibers in a cement matrix. At the millimeter-scale the composite response is analytically modelled to predict bridging stress versus crack width relationships. This response is used to determine the flexural behavior of structural roofing tiles. At the meter-scale (and kilometer-scale of distribution chains), life cycle assessment models are created to quantify the social, environmental, and economic impacts of the new composites. These are used for material composite design at all scales. Ultimately, a polypropylene-based fiber for reinforcing concrete will be created using life cycle assessment as a guiding design tool and with the ability to displace harmful asbestos reinforced concretes in developing countries.
Linking human genetic variation to population level phenotypic diversity and individual disease susceptibility [electronic resource]
Keywords: Genetics.

Following major efforts to assemble and annotate the human genome, a present challenge for human genomics is the functional interpretation of genetic variation in human health. This dissertation provides insights to the technical and molecular challenges of interpreting genomic variation, and presents successful case studies leveraging cross-disciplinary approaches. Chapter 2 characterizes gene expression variation and the resulting phenotypic impact in lymphoblastoid cell lines obtained across seven populations from the Human Genome Diversity Project. Chapter 3 clinically interprets an individual patient's cancer genome, identifies a novel putative driver mutation, and proposes a targeted therapeutic route. Chapter 4 explores a non-BRCA multi-generational familial pedigree with early-onset breast cancer and identifies a putative causal mutation. Together, these chapters present attempts to establish new approaches and methods to incorporate and assess the functional impact of genetic variation on human phenotypes and disease.
Look at That: Faunal Sightings and Tourist Satisfaction in the Peruvian Amazon
Keywords:  Department of Anthropology
ecotourism
Anthropology
Stanford
ecolodge
Amazon
rainforest
conservation
development
sustainable
ecotour
south america
economic
tourism
environment
tourist satisfaction
fauna
Thesis

Ecotourism is an increasingly popular conservation/development strategy being used throughout the tropics. Scholars have shown the positive impact of community run ecotourism lodges throughout Central and South America on conservation efforts, community empowerment, and economic stability within the region. To increase the popularity of ecolodges and by extension their conservation benefits, this research seeks to understand the motivation behind tourists’ expectations for and satisfaction of ecotourism vacations. Previous studies on tourism show the importance of promotional materials and pre-determined destination image on tourist satisfaction. This study is novel in applying this lens to an ecotourism venue. The impact of promotional materials, portrayals of the rainforest by the media and viewings of wild fauna on tourists’ overall satisfaction are investigated. Using Rainforest Expeditions’ ecolodge Refugio Amazonas in Peru as a case study, data collection on tourists’ expectations, observations on tourists’ reactions to charismatic wildlife sightings and ratings of varying trail experience are used to understand tourists’ overall ecotour satisfaction.
Results support the hypotheses that tourist motivations for attending the ecolodge as well as their predetermined destination image created a highly correlated relationship between charismatic faunal sightings and tour satisfaction. Materials promoting the lodge have been found to be over-selling the experience resulting in lowered overall satisfaction, especially for those tourists who expected “an adventure of a lifetime.” I also found that popular cultural portrayals of the rainforest did impact tourists’ expectations and resulted in lower satisfaction ratings when an abundance of primates, exotic birds and jaguars were not experienced. Overall, tourist satisfaction was largely dependent on sighting of charismatic fauna throughout their time in the rainforest due to expectations before arrival. This study has led to many concrete steps tropical ecolodges can take to modify promotional materials, increase the frequency of sightings and use popular rainforest media portrayals to increase tourist satisfaction.
Looking like a Roman, looking like a Greek [electronic resource] : viewing as cultural performance in the late republic and early empire
Keywords: Classics.

This dissertation explores the cultural conundrum captured in Horace's much-quoted aphorism: Graecia capta ferum victorem cepit; Greek art in Rome potentially signals both captive Greece and captivated Rome. Whether plundered or purchased, a Greek masterpiece on display might proclaim Rome's geopolitical and economic ascendancy, or the Romans' own sophistication, but it might also act as compelling evidence of Greece's artistic superiority. I focus on two bodies of evidence for how viewers responded to this semantic instability: Greek and Latin ekphrastic poems written in response to Greek artworks on display in Rome (Chapters 1 and 2); and wallpaintings inscribed with Greek and Latin texts from Rome, Assisi, Pompeii, and Ostia (Chapters 3 and 4). I argue that these ekphrastic texts and inscribed images showcase strategic answers to the question of how to look at Greek art through the eyes of a captor rather than a captive. Ranging from elite texts and grand residences, to the taverns frequented by non-elites, my case studies trace the cultural coding of visualities across the strata of Roman society. The project sheds light on the entanglement of art, empire, and identity in the Graeco-Roman world, demonstrating that viewing was one of the cultural practices through which Greekness and Romanness came to be defined.
Machine learning for model uncertainties in turbulence models and Monte Carlo integral approximation [electronic resource]
Keywords: Aeronautics and Astronautics.

While computational fluid dynamics (CFD) is playing an ever-increasing role in the design process, physical experiments are still required for final verification. There is a demand for certification through simulation, but there is a gap in predictive quality. Reynolds-averaged Navier-Stokes flow simulations have known deficiencies, especially for high Reynolds number flows with turbulent transition and separation, and higher fidelity Large Eddy Simulations (LES) and Direct Numerical Simulations (DNS) are not generally affordable. Quantification and reduction of uncertainty in simulation results is necessary, and yet it is rare for error bounds to be returned by a simulation, and progress towards more accurate turbulent closures in RANS models seems to have stalled. Today, however, the community is better equipped than ever to address this challenge. The rise in data science has driven the creation of tools and techniques to analyze and synthesize massive data sets. Most importantly, the data needed for statistical inference is available; computational budgets allow for RANS calculations on a number of input conditions and design settings, LES advances to increasingly complex geometries, and DNS continues to expand its Reynolds-number range. This dissertation harnesses data-driven approaches to address issues of uncertainty in predictive tools. First, the dissertation explores creating accurate models from data by replicating the behavior of a known model. Computational data is collected from the Spalart-Allmaras turbulence model, a neural network algorithm is trained on this data, and the learned model is re-embedded within a CFD flow solver. The robustness and accuracy of this procedure is explored as influenced by loss function choice, feature selection, and training data. Next, the dissertation considers model uncertainty in low-fidelity models. High-fidelity data from DNS of combustion (using finite-rate chemistry) are used to augment the low-fidelity flamelet progress variable-based RANS approach (FPVA). Supervised learning approaches are used to construct two error models, one for the local inaccuracies in the model and a second addressing the spatial correlation of these errors. These uncertainty models are combined to estimate the uncertainty in the FPVA model. Finally, a methodology is presented for quantifying the effects of input uncertainty on an output variable of interest. This is done by constructing an approximate model of the system using available data samples, and then using this as a control variate to reduced the squared estimation error in the output. Results are presented which demonstrate improved accuracy for a wide range of problem dimensions, function types, and sampling types. Taken together, these approaches indicate the potential of data-driven techniques to identify and reduce uncertainties in complex flow simulations.
Machine learning meets mammalian learning [electronic resource] : statistical tools for large-scale calcium imaging and the study of changing neural codes
Keywords: Electrical Engineering.

In this thesis, I describe my work creating computational and statistical tools for neuroscience, and the application of these tools to the study of how neural coding changes with learning. In particular, I apply these tools to study several facets of the dynamics of place cells in hippocampal area CA1. First, I describe a Bayesian decoding method for predicting an animal's position in a room solely from his brain imaging data. I use this method to demonstrate retention of spatial information despite changes in place coding population. Further, I demonstrate that place coding ensemble turnover resembles a random process that nevertheless contains significant information about the time of the experience. Secondly, I introduce and validate a method for extracting neural images and fluorescence traces from large-scale calcium imaging movies. I use this method to study the relationship between the place-coding properties of nearby cells in area CA1. Lastly, I apply these decoding and cell extraction methods to the study of how place cells change during learning. I find that there is significant refinement in the place code, and that the neural spatial information is correlated with the animal's ability to navigate. This final demonstration is consistent with the hypothesis that improved fidelity of the internal place-coding map underlies the animal's navigational learning. Taken together, the tools in this thesis are advancements that contribute to the ability of neuroscientists to process and glean meaning from large datasets, a challenge that is presently at the forefront of the field.