VictorJuiz/thesis huggingface dataset:
Multiple scattering reflection models theory, implementation and experimental analysis

Physically-based rendering (PBR) techniques have been widely used in photo-realistic and stylized image generation across film and real-time graphics. Along with physically based lighting models, microfacet-based reflection models developed using physical principles of surface reflectance form the foundation of PBR. While microfacet-based reflection models can represent light reflections on a wide range of rough surfaces, a major limitation of these models is that they only account for the single scattering of light, leading to energy loss and image darkening. Before PBR, artists used ad-hoc diffuse additions to compensate for this energy loss, but these types of fixes are difficult to use in PBR where any excess energy can cause images to blow out. Therefore, the broad adoption of PBR made this limitation even more pronounced for the application of microfacet BRDF models. In this thesis, we present two approaches to represent surface reflectance with multiple scattering effects. The first approach is the first closed form multiple scattering microfacet BRDF that leverages Zipin's classic paper which proves the number of reflections inside a specular v-groove structure is bounded. This solution improves upon the prior state-of-the-art multiple scattering BRDF by 10푥+ in terms of path-traced rendering convergence and performance. The second approach leverages advances in probabilistic distribution modeling using deep neural networks to develop a multiple scattering BRDF using Real-NVP. This is the first work to demonstrate the potential of normalizing flows for BRDF modeling and sample generation. In addition to presenting the theory and the implementation of these two models inside the PBR renderer, PBRT, we also present the first comprehensive experimental analysis comparing three state-of-the-art multiple scattering reflection models with the three most widely used single scattering reflection models (the GGX Smith, GGX V-groove and Cook Torrance BRDFs) using the MERL material database, a dataset with 100 measured isotropic materials with varying albedo, roughness and Fresnel index of refraction

Advisor: Hanrahan P. M. (Patrick Matthew)
James Doug L.
Marschner Steve
Multiscale solver for subsurface poromechanical problems

Solution of linear systems is often the bottleneck in large-scale subsurface modeling, especially when tightly coupled multiphysics systems are considered. Iterative linear solvers that are employed critically depend on efficient and scalable preconditioners to achieve robust convergence. The objective of this work is the development of scalable and efficient multilevel multiscale preconditioners targeting problems of geomechanics, single-phase flow and poromechanics on general polyhedral grids in one unified framework. We have developed a flexible unstructured coarsening framework that constructs a multilevel hierarchy of topological grid representations suitable for both nodal (finite-element) and cell-centered (finite-volume) discretizations. At every level, interpolation and restriction operators are defined by computing numerical basis functions using the Multiscale Restriction-Smoothed Basis (MsRSB) method, which has been additionally extended with a matrix filtering strategy designed to guarantee convergence of the smoothing iterations for problems that do not produce an M-matrix. We also develop a multiscale preconditioner for coupled poromechanical problems based on a combination of pressure and displacement basis functions and a block-triangular smoothing operator. Robustness and algorithmic scalability of the method are verified using a series of two and three-dimensional test cases including single-physics and coupled problems. In addition, this work describes an optimized parallel implementation of the proposed multiscale methods, its main computational kernels and data structures for representing the mesh hierarchy and multiscale operators. We investigate the performance and scalability of the developed multiscale solver and compare it to a state-of-the-art algebraic multigrid solver using a series of structured and unstructured grid test problems. Good weak and strong scaling is observed on up to 16 shared memory cores and 32 distributed memory nodes for a range of problems from 1 million to 140 million grid cells

Keywords: Energy Resources Engineering.
Advisor: Tchelepi Hamdi
Castelletto Nicola 
Tartakovsky Daniel
Multiwavelength Mitigation of Stellar Activity in Astrometric Planet Detection

Astrometry, referring to the measurement of stellar positions in the sky, has long been a promising technique for exoplanet detection. As the Earth orbits the Sun, for example, its gravitational pull causes the Sun to wobble with an amplitude of 0.65 milli solar radii. Exoplanets induce analogous reflex motion in their host stars, which can serve as astrometric signals. At its theoretical limits, astrometry would allow for the detection of planets smaller than previously observed by current exoplanet search methods. However, stellar activity may make these theoretical limits unreachable. Magnetic activity in the photosphere of a Sun-like star induces variability of order 0.5 milli solar radii in the position of the photocenter. This astrometric “jitter” creates a fundamental astrophysical noise floor preventing detection of lower mass planets at a single wavelength.
In this thesis, we investigate mitigation of this fundamental astrometric noise for Sun-like stars using correlations across wavelengths. To do so, we perform planet injection-and-recovery tests in five different wavelength passbands using astrometry simulations calibrated from solar data. We treat this problem in the limit of an ideal telescope to isolate the noise floor set by stellar activity. For a true solar analog and a planet at 1 au semi-major axis, we find the 6σ detection limit to be 0.01 Earth masses in the best single passband. We then show that combining information from pairs of passbands with highly correlated jitter but less motion in the redder band enables higher precision measurements of the common signal from the planet. Using this method improves detectable planet masses at 1 au by up to a factor of 10 at some wavelengths, and it sets the new 6σ detection limit across all passbands to 0.005 Earth masses. Given these results, we recommend that future astrometry missions consider proceeding with two or more passbands to progress towards astrometric planet detection by reducing noise due to stellar activity.

Keywords: Physics
Astrometry
Extrasolar planets
Extrasolar planets > Detection
Solar activity
Sunspots
Stellar activity
Starspots
Text
Thesis
Advisor: Macintosh Bruce
Graham Peter
Music, manuscripts, and missionaries in the early colonial Guatemalan Highlands

The Q'anjob'al and Chuj Mayans of Guatemala's Cuchumatán mountains fiercely resisted the Spanish colonial presence. From the earliest contact in 1525 to the late seventeenth century, chroniclers reported "imminent risk" to Spanish interlopers. And yet, those same Mayan communities embraced a European-style Catholic music tradition, as choristers, scribes, and composers. Local maestros documented and exchanged their repertoires, eventually leaving behind more than fifty volumes of music manuscripts. The same people who set "demon spirits" upon priests sang songs such as "De la sagrada Maria" (Of the sacred Mary). What power did music have that arms and scripture lacked? How did this group of remote and resistant villages become Central America's most robust center of Catholic choral music-making of its time? My dissertation picks up these questions through an examination of this "Huehuetenango collection" of manuscripts, of which only sixteen now survive. This project is the first major scholarly work dedicated to the historical context of this collection. With newly catalogued works and song analyses, this study brings to light material of an entire region of interconnected communities, recording local colonial-era language use, religious hierarchies, and social networks. I argue that the Huehuetenango collection offers rare evidence of early colonial lived experiences of the Q'anjob'al and Chuj Maya people and the Indigenization of a musico-religious tradition

Keywords: Music.
Advisor: Rodin Jesse
Greene Roland
Schultz Anna C.
"My other job" : volunteer content moderation as platform labor

Volunteer content moderation has been a crucial feature of virtual discussion spaces throughout the history of the social internet. Over the last decade, global social media companies have built out the infrastructure for volunteers to administer their own groups and communities. The social media platform Facebook, for example, reported that as of 2020, 70 million volunteers moderate discussion groups regularly used by 1.8 billion people worldwide. Despite its broad use by nearly a quarter of humanity, Facebook's structural opacity has unfortunately limited external access to conduct rigorous research of these spaces. In this dissertation, I examine volunteer moderation on Facebook from the theoretical perspective of the sociology of labor, incorporating insights from management studies and the field of communication. This research uses ethnographic methods and is designed around 41 in-depth interviews with volunteer Facebook admins and moderators who moderate groups that vary in both size and topic. I also introduce a new method for use in digital ethnography that I call over-the-shoulder observation. Analysis of these interviews, field notes, and notes from over-the-shoulder observation yielded important insights into the dynamics of Facebook-hosted group moderation, including a framework for understanding the work of moderation teams, an exploration of volunteer moderation as a route to capital accumulation, and an application of labor process theory to the moderator-platform relationship. More broadly, this dissertation reveals how volunteer moderators' work is shaped by the economics of the emerging platform ecosystem. I argue that the scholarly moderation literature must move beyond framing moderation practices simply through the lenses of normative ethics and effective user experience, and rather scholars must recognize that broader social and economic subjectivities of these actors shape how they make and understand moderation decisions

Keywords: Communication.
Advisor: Christin Angèle
Hancock Jeff
Turner Fred
Valentine Melissa (Melissa A.)
Myeloid cells in the tumor: a study on targeting myeloid-derived suppressor cells and activating macrophages for cancer immunotherapy

Colony stimulating factor-1 receptor (CSF1R) signaling is crucial for macrophage differentiation and survival. Inhibition of CSF1R through monoclonal antibodies and antagonists has been widely explored in preclinical studies due to its ability to deplete pro-tumorigenic tumor-associated macrophages. However, CSF1R inhibition has had limited clinical and therapeutic efficacy, necessitating the need for further investigation into the effects of CSF1R blockade on myelopoiesis in the tumor microenvironment. In this study, we report that deletion of CSF1R in an inducible knockout mouse model leads to the expansion of CXCR2+ granulocytic-myeloid derived suppressor cells (G-MDSCs) in both thioglycollate-induced peritonitis and tumorigenesis. Further, we demonstrate that targeting CXCR2+ G-MDSCs could increase macrophage programmed cell removal (PrCR), and combination with anti-CD47 monoclonal antibody treatment could serve as an effective therapeutic strategy for cancer treatment. Lastly, we begin a broader study on tumor clearance by macrophages through the lens of “eat me” signal calreticulin (Calr), ultimately revealing key molecular components of the mechanism of Calr secretion by macrophages for PrCR.

Keywords:  Department of Biology
Biology
Macrophages
Myeloid-derived suppressor cells
Tumor Immunology
Calreticulin
CD47
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Thesis
Advisor: Weissman Irving
Majeti Ravindra
Stearns Tim
Narratives of displacement : the spatialization of power in Chicanx/Latinx cultural production

My study centers around two main questions: 1) How have Latinx cultural producers imaginatively and tangibly intervened in the processes of gentrification and displacement? 2) What strategies have Latinx communities across diverse geographical contexts utilized to advance more equitable forms of social and spatial change? In Chapter One: "Placing Displacement and Dispossession: Reimagining Spatial Agency in Greater Los Angeles, " I begin with an analysis of Helena Maria Viramontes' Their Dogs Came with Them. In the wake of mass displacement during the 1960s, I argue, the built environment became defamiliarized, hostile terrain to the residents of East LA, particularly the pedestrians. I explore the creative strategies Viramontes' characters use to preserve their presence and survive their new social reality. I then turn to Héctor Tobar's The Barbarian Nurseries. I analyze Tobar's vision of Greater Los Angeles County as a site of pronounced social and economic inequality alongside an examination of the figure of the Latina domestic worker in the suburbs. In Chapter Two, "In Residence: Diasporic Memory-Work in Central American and Chicanx Cultural Activism" I examine of the gentrification of the Mission District of San Francisco, focusing specifically on the role of rising income inequality, rents, and home values in the demographic transformation of the neighborhood. I argue that the designation of Calle 24 Cultural District attempts to intervene directly in the gentrification process by utilizing urban planning strategies to contend with the loss of its traditionally working class Latinx culture. I then consider how Latinx residents' use cultural production to protest racial and ethnic stratification and heal from the violence of displacement. Among them, I explore Robert Lovato's memoir's assertion that the 1932 Matanza and 1980s civil war inform Salvadoreans' contemporary struggles with gang-violence and forced migration to the United States. I argue that Lovato's critical framework, "unforgetting" is a powerful tool for the writing of familial hemispheric history and seeking truth and reconciliation amongst legacies of violence. In Chapter Three: "Recovering Mexican Chicago— Literature as Historical Archive, " I consider poet José Olivarez's participation in spoken word spaces and his mentorship of youth as I highlight the way he writes against racial and ethnic inequality in contemporary Chicago. I contend that Olivarez's practice of Chicanx worldmaking in his poetry collection Citizen Illegal demonstrates the emancipatory potential of imagined communities where low-income people of color transform, on their own terms, the unjust social, economic, and cultural systems that structure our society. I then turn to Sandra Cisneros' Caramelo and House on Mango Street and describe them as active representations of "creative placemaking.".

Advisor: Moya Paula M. L.
Fishkin Shelley Fisher
Frank Zephyr L.
Saldívar José David
Natalie Cross' NSC ePortfolio

This document is an archive of an electronic portfolio (ePortfolio) produced as a capstone requirement for the Notation in Science Communication. In their ePortfolios, NSC students demonstrate how they have met the NSC learning outcomes. These learning portfolios detail students’ growth and development as scientists and science communicators rather than showcasing only their best work. ePortfolios are reviewed and approved by faculty, earning students a special designation on their official Stanford transcript that reflects their science communication acumen.

Keywords: Communication in science
Marine biology
Marine ecology
Marine animals
Climatic changes
Nature conservation
Information visualization
Mixed materials
Image
Text
Article
Essay
Geospatial data
Map
Photograph
Presentation slides
Remote sensing imagery
Report
Thesis
Essays
Cartographic dataset
Maps
Photographs
Remote-sensing images
Dataset
Advisor: Pittock Sarah
Fabbro-Johnston Deana
National Security and Academic Freedom: How American Universities Navigate Great Power Competition

How do American universities navigate the tension between national security and academic freedom that arises during periods of great power competition? To answer this question, I examine two time periods when intense rivalry between the US and its rival country drove the American government to scrutinize universities: from 1947 to 1957, which encapsulates the Second Red Scare, and from 2013 to present day, which covers US-China great power competition. Across these two case studies, I find reoccurring patterns in the threat perceptions and mitigating strategies of the US government, university administrators, and professors. US government officials express concerns that foreign rivals are taking advantage of the openness of American universities to steal research and to brainwash students. These threat perceptions have led the government to investigate faculty accused of ties to foreign rivals, create new laws and policies, and publicly communicate to university administrators to try and mitigate these concerns. Much of these government strategies achieve success by pressuring administrators into complying with the government’s goals or by deterring faculty from carrying out certain actions. Some university administrators and faculty, meanwhile, argue that the government’s increased involvement threatens the core values of their institutions, especially academic freedom. A few have publicly expressed these concerns in attempts to pressure the government to limit its policies. Many university administrators, however, choose to cooperate with the government to protect their funding or because they agree with the government’s perspective. To protect themselves, many faculty members also limit their behavior and censor their studies. These trends indicate that balancing national security and academic freedom represents a difficult issue, one for which the US government, university administrators, and faculty have failed to reach a satisfactory solution. Modern developments in dual use technology and globalization only exacerbate this tension. This thesis hopes to inspire greater communication between policymakers, university administrators, and university faculty so all sides understand one another’s concerns.

Keywords: Center for International Security and Cooperation
research security
academic freedom
China
Second Red Scare
university
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Thesis
Advisor: Stearns Dr. Tim
Vardi Dr. Gil-li
Natural experiments in economics

What happens when an entire town suddenly receives a huge wealth shock? For over a century, Spain has conducted a national lottery which often results in the random allocation of large cash windfalls to one town. Leveraging data on lottery ticket expenditures, we match winning towns to non-winning towns with equal winning probability. For towns that won in recent decades, consumption of durables increases while employment, businesses, and migration to the town decrease. An analysis of a century of winners reveals a stark and persistent population increase for towns that won after the Civil War. My results suggest a limited role for wealth shocks in spurring economic growth outside of large recessions. In chapter 2, I study the effect of parenthood on the lives of low-socioeconomic-status parents. My data consists of longitudinal, high frequency administrative records from a large urban U.S. county, covering housing, treatment for substance use disorder (SUD), enrollment in government assistance programs, and crime. Using an event study design, I find that new parenthood leads to increases in housing instability and government assistance use. New parenthood also decreases crime and increases take-up of treatment for substance use disorder. The effects of parenthood are heterogeneous by race and vulnerability to mental health disorders. In chapter 3, I examine the extent to which education is a valuable investment for academically marginal students. I ask this question in the context of the Dominican Republic, where schooling is mandatory until eighth grade and many students must decide between continuing on to high school or entering the labor force. I estimate the value of years of secondary education and high-school completion for low-performing students by exploiting the passing cutoffs on the eighth and twelfth grade national exams. I find that students who barely pass the exam in eighth grade complete more years of education, are more likely to enroll in college and experience higher earnings. A broad implication of these facts is that education has large and positive returns even for the lowest part of the ability distribution

Keywords: Economics.
Advisor: Hoxby Caroline Minter
Diamond Rebecca (Of Stanford University. Graduate School of Business)
Persson Petra
Negotiating equality at home : a historical study of informal intimate relationships in 20th century Colombia

This dissertation's main goal is to unearth the history of the legal changes that granted property rights protections to concubine women living in out-of-wedlock families in 20th century Colombia. Through the study of court cases, oral history interviews, newspapers, and legislative initiatives, I discover the agents of change, detail their strategies, and elucidate their losses and victories. I found that the absence of family law regulations deepened structural conditions of gender inequality in out-of-wedlock families, as control over property and economic means in informal relationships fell decidedly on men's side. Facing a total absence of Family Law protections, concubine women turned to the civil and labor courts to fight for their property. Therefore, the study of concubine women's fights reveals how these women attempted to alter the gendered order inside the family, rejecting the role of dependent and unpaid laborer. This dissertation sits at the intersection of legal history, family law, and feminist studies, and contributes to these distinct scholarly fields. First, I shed light on the urgency of studying the relationship between property and gender in informal intimate relationships as a separate study of the role of property within marriage. Second, I propose to add a level of complexity to the feminist critique of marriage. What I find with this research is that marriage is a double-edge sword as both an engine of women's oppression and a guarantor of certain property rights for women who enter it. Third, I propose a revision of the role of the Colombian feminist movement and its involvement with changes to Family Law

Keywords: Law JSD.
Advisor: Kessler Amalia D.
Banks Ralph Richard
Jaramillo Vélez Isabel Cristina
Rosenfeld Michael J.
Neither history nor story : common soldiers write the American Civil War

After the American Civil War Union and Confederate common soldiers wrote numerous memoirs, novels, and essay collections in an effort to influence how the war and their rank would be remembered. These have been largely neglected by scholars of American history and literature. This study recuperates these works as an important part of early debates over Civil War memory. Chapters consider common soldiers' attempts to shape sectional reconciliation, competition with their former officers in the Civil War literary field, and strategies for representing mass experience

Advisor: Jones Gavin Roger
Fishkin Shelley Fisher
Ruttenburg Nancy