VictorJuiz/thesis huggingface dataset:
Eevee: Transforming Images to Bridge High-level and Low-level Understanding
Keywords:  Department of Computer Science
Computer Science
Stanford
Stanford Engineering
Stanford School of Engineering
Human-computer interaction
HCI
Image editing
Photo editing
Graphics
Computer Vision
Thesis

Images are central to communication, documentation, and a general understanding of the human world, and because their power so often arises from intangible subjectivities that currently elude computers, it is ever so vital that systems understand the world in the same way we do. People understand and think about images at a high level, but they’re currently constrained to work with images via low level tools and edit operations. We introduce a photo-editing system, Eevee, that can take a high level goal from a user and automatically translate it into a series of low level image edits, a step towards empowering people to interact with images at a higher semantic level. By situating our task within the domain of humorous memetic edits, building upon the notion of visual analogies to drive domain-shifting edits, and utilizing the objective knowledge afforded to us by modern computer vision technology (objects, their segmentations, their relationships, and their attributes), we produce a focused editing method that can link low level image syntax to high level image semantics.
Effect of constraint on mechanical behavior of polymer layers and membranes in energy applications
Keywords: Mechanical Engineering.

The role of mechanical constraint is well known in the mechanical behavior of engineering materials such as adhesive joints and alloys. However, in the case of polymer layers and membranes, the effect of mechanical constraint is not always understood. In particular, in energy technologies, device geometry is becoming increasingly complex but the role of mechanical constraint is not explored. In proton exchange membranes (PEM) fuel cells, the PEM is constrained by the adjacent current collector plates such that the membrane can only deform in the flow channel areas. I showed that the tearing energy decreases with increasing constraint associated with a smaller plastic zone and is much lower than the tearing energy with no constraint. In photovoltaics, the backsheet structure is a layered film where the tearing behavior of the individual layers does not necessarily represent the tearing behavior of the entire backsheet. I showed that such characteristic arises from the interaction between the individual layers during the tearing process, where one layer of the backsheet is mechanically constrained by its neighboring layers and the layers may debond from each other. Finally, I present the mechanism through which mechanical constraint enhances the stiffness of a novel polymer composite electrolyte for batteries. The composite electrolyte is composed of a silica aerogel monolith filled with a polymer electrolyte. When the voids of the aerogel are filled with the polymer, the polymer constrained the bending of the cell wall and effectively enhanced the stiffness of the composite. This work highlights the importance of considering the effects of mechanical constraint as it can lead to surprising effects on the mechanical and fracture properties of materials.
The effect of pressure on iron compounds and the implications for the earth's mantle and core
Keywords: Geological and Environmental Sciences.

Understanding the high-pressure behavior of iron and its various alloys is a fundamental step in gaining insight into the deep Earth. Iron is the most common transition metal within the mantle and is the primary element in the core. In order to explore the properties of iron compounds and alloys at high pressures, the conditions of the deep Earth were replicated in diamond anvil cells and the resulting changes were monitored by a various suite of synchrotron techniques. X-ray emission spectroscopy was used to monitor the spin state of the polymorphs of iron hydroxides up to 85 GPa. FeOOH has four polymorphs: goethite (alpha - FeOOH), akaganeite (beta - FeOOH), lepidocrocite (gamma - FeOOH), and a high-pressure phase, epsilon - FeOOH. The structural changes of these polymorphs as a function of pressure were examined using X-ray diffraction to generate equations of state for beta - FeOOH and gamma - FeOOH. Comparing the equation of state results for the beta and gamma phases with recently published data on the alpha and epsilon phases, the beta - FeOOH exhibits distinct behavior from the other three polymorphs, as it is significantly less compressible and does not undergo a spin transition. A systematic examination of these iron hydroxide polymorphs as a function of pressure provides insights into the relation between electronic spin transitions and structural transitions in these OH- and Fe3+ bearing phases that may have implications on understanding of the water content of the mantle. We collected a series of phonon excitation spectra using nuclear resonant inelastic x-ray scattering on 57Fe-enriched on various iron alloys, FeO, Fe3C, FeS and those with varying nickel content (Fe0.9Ni0.1, Fe0.8Ni0.2 and Fe0.7Ni0.3) at pressures up to 40 GPa at room temperature. The phonon density of states were used to extract each composition's force constant and  - factors in order to evaluate their individual effects on stable iron isotope fractionation. This work explores the effect of various light elements, the role of increasing nickel content and the effect of spin transitions on iron isotope fractionation. It provides insights into the potential records left by core formation during planetary differentiation. Radial X-ray diffraction was used in combination with nuclear resonant inelastic x-ray scattering to determine the bulk strength of two iron-nickel alloys (Fe0.88Ni0.12 and Fe0.8Ni0.2) at pressures up to 70 GPa. The results were then used to extrapolate to inner core pressures and temperature in order to evaluate the strength of the inner core. As shear strength is a measure of a material's resistance to flow, these results support dislocation creep as the dominant deformation mechanism in the Earth's inner core.
The effect of psychological pain on financial behaviors
Keywords: Business.

This dissertation comprehensively examines a crucial factor that underlies nearly every financial decision that consumers make—psychological pain. The first essay of the dissertation shows that while lacking ownership over a financial decision to spend amplifies the pain associated with losing money, it actually alleviates the pain associated with feeling financially irresponsible. The second essay of the dissertation demonstrates how psychological pain (to avoid losing one's savings) can spill over to another important financial behavior—the decision to invest one's savings. Specifically, this essay shows that when consumers incur more effort to build their savings, they become less willing to invest them. Finally, the third essay argues that the anticipation of future psychological pain can affect consumers' choice of how they pay (with cash or with card) and that they will strategically avoid repeating the painful experience of feeling that one is financially irresponsible by opting to pay with non-trackable payment methods such as cash instead of debit or credit cards.
The effectiveness of white-collar crime enforcement : evidence from the war on terror
Keywords: Business.

This paper studies the deterrent effect of criminal enforcement on white-collar criminal activities. Using the 9/11 terrorist attacks as a shock to the FBI's allocation of investigative resources and priorities, and variations in the Muslim population in the United States as a measure of geographic variations in the shock, I examine two questions: (1) Does the bureau's shift to counter-terrorism investigations after 9/11 lead to a reduction in the enforcement of laws targeting white-collar crime? (2) Does white-collar crime increase as a result of less enforcement? Using a difference-in-differences estimation approach, I find that there is a significantly greater reduction in white-collar criminal cases referred by FBI field offices that shift their investigative focus away from white-collar crime to counter-terrorism. I also find that areas overseen by FBI field offices that shift their attention from white-collar crime to counter-terrorism experience a significantly greater increase in wire fraud, illegal insider trading activities, and fraud within financial institutions.
Effects of Augmented Reality Projection Obstructions on Social Interactions Between Augmented Reality Headset Wearers and Non-Wearers
Keywords: Augmented reality
mixed reality
social interactions
social presence
Thesis

Augmented reality smart glasses have made attempts to enter the public sphere as a consumer product. These attempts have not been successful, and one of the reasons stems from negative interactions between people wearing the smart glasses and those not wearing them. One possible root cause of this negative interaction may be from augmented projections obscuring conversation participants visually. This paper seeks to explore why people may have negative interactions in these circumstances. We take measures of social presence, interpersonal attraction, and partner closeness, among others. After studying 96 pairs of participants, we found that when projections obscured a headset wearer’s partner, the headset wearer experiences less social presence than their partner. This has implications on the way we may perceive reality should smart glasses ever become a public consumer product.
Effects of bottom-up and top-down manipulations on visual object processing across the brain
Keywords: Psychology.

Object recognition is an incredibly important process in day to day life, and is accomplished by the human visual system automatically and effortlessly. However, this process is rarely done in isolation from goal-oriented behavior (or task) performed by the subject. Though much is known about the passive processing of objects in the visual system, far less is understood in both: (1) How tasks affect known responses to objects in visual cortex, and (2) How objects are represented in regions of higher cognition such as prefrontal cortex. Chapter I provides an overview of the existing knowledge regarding object recognition and visual processing of objects, the effects of task engagement on responses in high-level visual cortex, and what is currently known on representations of objects in prefrontal cortex. The study described in chapter II examined how the information content of object classes, or category representations, in different cortical regions changed across three qualitatively different tasks. Here we find that while responses in high-level visual cortex contain robust and task-general representations of visual categories, responses in prefrontal cortex are flexible and task-dependent, supporting their respective functional roles. The study in chapter III further dives into the effects of top-down signals, as well as bottom-up signals, in finer increments and in smaller (and independently derived) of the cortical expanses explored in the first study. The findings from this study reveal a far richer functional heterogeneity in high-level visual cortex than was previously assumed, capturing a diverse set of response profiles to bottom-up and top-down manipulations, as well as their interactions. In prefrontal cortex, no areas are engaged by purely bottom-up manipulation of stimulus, and only a small subset is engaged by the on-task condition, alluding to hypothesized mechanisms of attention. Together, these results expand what is known about the effects of task in high-level visual cortex, as well as the involvement of prefrontal cortex in object processing.
The effects of government policies on individual education, labor market and health outcomes
Keywords: Economics.

I examine the impacts of a state government policy in California, and two national South African government policies on individual outcomes. In Chapter 2 we find evidence that California's Paid Family Leave (PFL) program improved child health outcomes in kindergarten with the greatest improvements experienced among children from less advantaged backgrounds. Chapter 3 demonstrates that the additional income from the South African means-tested unconditional cash transfer program, the child support grant, increases enrollment among all female children and decreases work inside the home for older female adolescents. Lastly, in Chapter 4 I find that the South African need-based college loan program, NSFAS, significantly increased the probability of graduation, and reduced the time taken to complete the qualification among those who graduate. These findings suggest an important role for government intervention in reducing inequality and increasing intergenerational mobility.
Effects of Land Use and Land Cover Change (LULC) and Climate Change on Mosquito-Borne Disease Transmission in Colombia: An Integrated Spatiotemporal Approach
Keywords: MacDonald, Andy
Earth Systems
School of Earth
Energy &amp; Environmental Sciences
Thesis

Human modification of the natural environment continues to create conditions under which mosquito-borne diseases thrive. In this project, I identify associations between environmental change and the Zika epidemic in Colombia in 2016. Colombia had the second highest number of Zika cases in the Americas after Brazil, totaling over 100,000 suspected and confirmed cases. Zika is an arboviral disease transmitted by Aedes mosquitoes. Previous work has shown that transmission of Zika depends on elevation, forest cover, urban cover, temperature, and precipitation. However, the impacts of changes in these factors, rather than their current states, have yet to be studied. I used spatiotemporal remote sensing imagery to measure the changes in forest cover, urbanization, temperature, and precipitation in Colombia and built a regression model to assess their relationship with the presence and incidence of Zika transmission. For comparison, I also observed the impacts of these variables on other mosquito-borne diseases in Colombia, including dengue and chikungunya (also transmitted by Aedes mosquitoes) and malaria (transmitted by Anopheles mosquitoes). Forest loss was positively associated with the presence of Aedes-borne diseases, whereas forest gain was negatively associated with the incidence of Aedes-borne diseases. In some cases, the environmental drivers' states across space and rates of change across time showed opposite effects on disease
presence, which highlights the importance of assessing environmental drivers spatiotemporally. As highly detailed datasets on environmental change become more accessible, more eco-epidemiological analyses like this project can help to clarify the impacts of environmental change on human health.
Effects of Latency and Refresh Rate on Force Perception via Sensory Substitution by Force-Controlled Skin Deformation Feedback
Keywords:  Department of Mechanical Engineering
Stanford University Department of Mechanical Engineering CHARM Lab
Haptics and Interfaces
Thesis

Latency and refresh rate are known to adversely affect human force perception in bilateral teleoperators and virtual environments using kinesthetic force feedback, motivating the use of sensory substitution of force. The purpose of this study is to quantify the effects of latency and refresh rate on force perception using sensory substitution by skin deformation feedback. A force-controlled skin deformation feedback device was attached to a 3-degree-of-freedom kinesthetic force feedback device used for position tracking and gravity support. A human participant study was conducted to determine the effects of latency and refresh rate on perceived stiffness and damping with skin deformation feedback. Participants compared two virtual objects: a comparison object with stiffness or damping that could be tuned by the participant, and a reference object with either added latency or reduced refresh rate. Participants modified the stiffness or damping of the tunable object until it resembled the stiffness or damping of the reference object. We found that added latency and reduced refresh rate both increased perceived stiffness but had no effect on perceived damping. Specifically, participants felt significantly different stiffness when the latency exceeded 300 ms and the refresh rate dropped below 16.6 Hz. The impact of latency and refresh rate on force perception via skin deformation feedback was significantly less than what has been previously shown for kinesthetic force feedback.
The effects of upwelling-driven hypoxia on sea urchins in California current kelp forests
Keywords: Biology.

Global climate change is increasingly exposing marine organisms, communities, and ecosystems to a variety of physiologically stressful conditions. Understanding how organisms respond to realistic exposures to physiological stressors, and how these responses may scale up to population- and ecosystem-level impacts, is crucial to understanding and predicting the impacts of climate change. Most earlier experimental approaches to this problem have focused on assessing organism responses to constant levels of a single physiological stressor, but physiological stresses on marine organisms often occur at sublethal levels, with temporally variable exposure patterns, and in combination with other stressors. In this dissertation, I use sea urchins in California Current kelp forests as a model system to address questions about the roles of sublethal exposures, temporal exposure patterns, and multiple-stressor interactions in shaping organisms' and ecosystems' responses to upwelling-driven coastal hypoxia. By using a decade-long dataset of nearshore dissolved oxygen conditions from the Monterey Bay kelp forest as a basis for designing and interpreting laboratory experiments, I find that coastal hypoxia is most likely to impact kelp forest ecosystems via sublethal effects on the ecological roles of sea urchins, that longer-term patterns of exposure to sublethal hypoxia have potential impacts on sea urchin populations and kelp forest ecosystems, and that realistic combinations of multiple stressors produce interactive and unexpected responses in sea urchins. Taken together, the results of this dissertation suggest that sublethal exposures, temporal exposure patterns, and multiple-stressor interactions all modulate individual sea urchin responses to upwelling-driven hypoxia, with potential consequences for populations and ecosystems. More broadly, the results indicate that climate change experiments need to take these different aspects of realistic stressor exposure into account, in order to produce useful and informative results. To that end, the fourth chapter of this dissertation describes a low-cost, versatile experimental control system that other researchers and students can use to implement realistic, temporally variable experimental exposures to multiple stressors. Therefore, this dissertation contributes to both the conceptual and technical advancement of experimental climate change research in marine systems.
Efficient sequential reliability-based design optimization with adaptive kriging inverse reliability analysis
Keywords: Aeronautics and Astronautics.

In this thesis, new methods for reliability-based design optimization (RBDO) are presented. The Adaptive Kriging Inverse Reliability Analysis (AKIRA) algorithm and a multifidelity sequential RBDO algorithm are introduced and demonstrated on a complex multidisciplinary supersonic nozzle design problem. AKIRA demonstrates competitive performance with other reliability analysis algorithms while also benefiting from the solution of the inverse reliability analysis problem during RBDO. The proposed sequential RBDO algorithm mitigates the cost of solving the RBDO problem by decoupling the optimization and reliability analyses, thereby reducing its solution to a series of deterministic optimizations. The method is motivated by anchored decomposition, has guaranteed convergence inherited from trust region methods, and is shown in certain cases to be a generalization of existing sequential RBDO methods. It also derives enhanced efficiency by incorporating lower-fidelity models when available. The final demonstration of the proposed algorithms on an industrial-type problem, the supersonic nozzle, shows that the solution of RBDO problems for complex realistic engineering applications is well within reach.
Eigenvalues in multivariate random effects models
Keywords: Statistics.

We study principal component analyses in multivariate random and mixed effects linear models. These models are commonly used in quantitative genetics to decompose the variation of phenotypic traits into consistuent variance components. Applications arising in evolutionary biology require understanding the eigenvalues and eigenvectors of these components in high-dimensional multivariate settings. However, these quantities may be difficult to estimate from limited samples when the number of traits is large. We describe several phenomena concerning sample eigenvalues and eigenvectors of classical MANOVA estimators in the presence of high-dimensional noise, including dispersion of the bulk eigenvalue distribution, bias and aliasing of outlier eigenvalues and eigenvectors, and Tracy-Widom fluctuations at the spectral edges. A common theme is that the spectral properties of the MANOVA estimate for one component may be influenced by the other components. In the setting of a simple spiked covariance model, we introduce alternative estimators for the leading eigenvalues and eigenvectors that correct for this problem in a high-dimensional asymptotic regime.
Elucidating the Presence and Purpose of Competence and Progression in Primary Mammalian Cells
Keywords:  Department of Biology
Biology
cell cycle
competence
progression
cell growth
Thesis

Mammalian cells require the presence of growth factors in order to enter the cell cycle and divide. However, constant exposure to growth factors is not always required for cells to divide in tissue culture. In fact, giving cells two short pulses of growth factors eight hours apart is just as effective as giving cells constant growth factors in driving them into the cell cycle. This suggests that there are two time points within the G1 phase of the cell cycle during which growth factor stimulation is required. The first, competence, prepares the cell to respond to the second, progression. Progression causes the cell to continue through the restriction point and into the cell cycle. Whether competence and progression are present in primary human lung fibroblasts remains unclear. To characterize the presence of competence and progression in primary mammalian cells, we released primary human lung fibroblasts from serum starvation and measured cell cycle phase and cell size changes over time. In both constant and pulsed growth factor conditions cell cycle progression and cell growth were similar. Furthermore, we show that there is very little cell growth in the period of G1 between competence and progression. This suggests that providing a cell with a competence factor is not sufficient to induce the cell growth required for G1 exit.