VictorJuiz/thesis huggingface dataset:
Evaluating the Use of Optical Gas Imaging Cameras for Above Ground Facilities

Natural gas is the largest primary energy source in the United States. Reliance on natural gas is only increasing as its role in electricity systems becomes more significant and that of coal diminishes. While this has air quality and health benefits over the use of coal, the global warming potential of methane - the primary component of natural gas - cannot be ignored. In order to mitigate methane leaks, periodic leak detection and repair programs are required in the United States. Various different technologies exist to detect and/or quantify methane leaks. Studying them and evaluating their performance is an important step in evaluating equivalence in emissions reductions between technologies.
In this study, we evaluate the performance of two optical gas imaging cameras. The first is the FLIR GF320, an infrared camera, which we coupled with the Providence Photonics QL320 to enable it to quantify methane leaks. The second is the Rebellion Photonics mini-GCI, a hyperspectral imaging camera, which provides automated alerts when a leak is detected. Experiments to test the two systems were carried out at the Methane Emissions Technology Evaluation Center in Fort Collins, Colorado over two weeks. We tested both technologies at a variety of leak size and imaging distance combinations. In order to better simulate real-world conditions, we also tested the performance of the two systems in the presence of different types of interference. For the first technology, we evaluate the quantification performance and for the second, the detection performance.
We report performance metrics at different distances, interference scenarios and leak sizes in the case of Rebellion. The two technologies differ in terms of automation, detection and quantification capabilities, imaging distance and minimum observable leak size. Quantification accuracy of the FLIR + Providence system was poor. Machine learning algorithms may be able to improve the quantification accuracy in this kind of system. The Rebellion Photonics mini-GCI had a high false positive rate under most conditions and might benefit from adjusting its sensitivity to allow some smaller leaks to go undetected while issuing fewer false positives. Different types of interference had either no effect or a negative effect on the performance of each technology. More data points are needed to gain tighter confidence intervals around the statistics presented.

Keywords:  Stanford University
School of Earth Energy &amp; Environmental Sciences
methane
detection
quantification
Thesis
Advisor: Brandt Adam
“Every Day, Every Moment Concerned about Their Safety:” An Exploration across Contexts of Early Childhood Educators’ Safety-Related Identities

Contemporary scholarship and existing state policy have identified health and safety as essential elements of high-quality early childhood education (ECE). The perceptions of ECE teachers with regard to safety, however, remain largely unknown. Sociological and psychological understandings of identity figuring suggest that these ECE teachers’ beliefs are shaped by the contexts of their work. Through in-depth qualitative interviews, this grounded theory study explores how six early childhood teachers, working in three different types of preschool centers in the San Francisco Bay Area, perceive their safety-related professional roles (termed safety-related identities) within the context of their centers. Thematic analysis of interviews revealed 20 distinct safety-related identities that span child physical, emotional, and health safety, as well as teacher safety responsibilities. After triangulating interview findings with safety-related documentation across centers, the teachers in this study appear to have both common and unique safety understandings. With safety understood as a constant priority in their practice, all teachers were found to hold multiple safety-related identities at any given time, describing multi-tasking or negotiating between those identities to accommodate the diverse expectations of their work. These commonalities are noteworthy in and of themselves, while the divergences point to contextualized organizational priorities, teachers’ diverse personal experiences, and varying socioeconomic compositions across the neighborhoods studied. In light of these findings, implications and recommendations are provided for early childhood teacher educators and policymakers to consider how to better prepare the ECE workforce for the provision of high-quality safety in practice.

Keywords: preschool teachers
early childhood education
teacher beliefs
teacher role
child safety
teacher well-being
Stanford Graduate School of Education International Education Policy Analysis
Thesis
Evolution in the Portrayal of Chinese Forces in Chinese War Films

The main research questions this thesis aims to answer would be “How has the portrayal of Chinese forces evolved and changed in Chinese war films?” This question came about as stark differences can be noticed between Chinese war films produced before and after the 1980s. As the Chinese state had a large role in the Chinese film industry before the 1980s, the themes and character portrayal of war films had to align more with the state’s intention. Many pre 1980s war films centered around the glorification of Chinese victory and had a strong focus on Maoist ideology. However, Mao’s death in 1976 and China’s decision to undergo reform and opening in 1978 removed the priority for ideals such as socialism and nationalism to be propagated to the masses. Instead, there was an increased focus on the liberalization of the film industry in order for Chinese films to compete internationally and with other studios, such as Hollywood, especially in the post 1990s period. Hence, directors had a larger say in portraying the central message of the film, leading to war films being used as a backdrop for the exploration of the individual and their relationships. This thesis asserts that while pre 1980s war films were centered around Maoist ideology, portraying loyal and sacrificial soldiers, post 1980s movies were much more concerned with individual stories and the exploration of the individual’s thoughts and feelings. This argument will be laid out in 3 chapters.

Keywords:  Stanford Global Studies
Stanford Global Studies
East Asian Studies
Chinese war films
Chinese forces
Thesis
Advisor: Ma Jean
Evolution of the charge density wave state in the rare-earth tritellurides under uniaxial stress and disorder

Materials with strong electron correlations often exhibit a complex interplay between competing or coexisting ordered phases, such as charge order, magnetism, and superconductivity. Model systems which isolate just one of these components, however, can provide a practical path for navigating this complexity. This dissertation provides detailed studies of the behavior of the rare-earth tritellurides (RTe3 where R=Y, La-Nd, Sm, Gd-Tm) a candidate model system under two different perturbations, namely uniaxial stress and disorder. First, however, I present the results of analytical and numerical modeling of heat flow in measurements of the AC elastocaloric effect (AC-ECE), a new experimental tool that I use to investigate the title compounds. My work demonstrates that the details of the frequency-dependent sensitivity in AC-ECE measurements are highly nontrivial, and I present both intuitive explanations of these effects as well as a quantitative match with experiment. I apply the AC-ECE technique to explore the effects of in-plane uniaxial stress on the CDW transitions in both ErTe3 and TmTe3. A combination of AC-ECE measurements, together with in-plane and out-of-plane elastoresistivity measurements, clearly detects changes in the critical temperatures, transport anisotropy, and thermodynamic quantities as a function of strain. Finally, I describe the transport, thermodynamic, and scattering characteristics of single crystals of PdxErTe3, in which neutral Pd atoms intercalated between the Te bilayers act as a weak random potential. This work has established RTe3 as a model system for studying the interplay of unidirectional CDW formation, in-plane uniaxial stress, disorder, and superconductivity. Further investigation of the inter-relation of these effects could have direct bearing on a range of other material systems of current interest

Keywords: Applied Physics.
Advisor: Fisher Ian R. (Ian Randal) 
Hwang Harold Yoonsung
Kivelson Steven
Evolutionary genomics of malaria hosts and parasites

Malaria caused by the replication of Plasmodium falciparum parasites within human red blood cells (RBCs) remains a leading cause of human death by infectious disease. Over several thousand years, high childhood mortality from malaria has produced strong selection for human resistance, mostly via genetic RBC diseases like sickle cell anemia. On much shorter timescales, anti-malarial drugs have also imposed strong selection on genetic drug resistance in malaria parasites. Therefore, the ultimate goal of malaria elimination can be served by developing treatments and drug policies in the context of the evolution of both malaria hosts and parasites. This dissertation explores the history of genetic adaptation in malaria in three parts. First, I use laboratory experiments to demonstrate that natural, 'healthy' variation in human RBCs has substantial effects on P. falciparum growth rate. This identification of novel, protective alleles and phenotypes that are not strongly deleterious may help lead to new malaria therapies. However, I find little evidence that subtle protective variation has experienced positive selection in Africa. Second, I explore the stronger possibility of host adaptation over deeper time scales using ~9,000 protein sequences from 24 species of mammals infected by Plasmodium or related blood parasites. I find that mammalian proteins linked to malaria in the literature have experienced ~3 times more positive selection in the last 100 million years than proteins that have not. Widespread, non-deleterious host adaptation to malaria is therefore possible, but perhaps not on timescales relevant to humans. Finally, I combine new data and historical records from the west African country of Angola to document the extremely rapid evolution of genetic drug resistance in P. falciparum parasites over the last 20 years. This result suggests that changes in drug administration are badly needed in Angola, where malaria deaths are on the rise. An evolutionary approach to the biological control of malaria will allow for the development of therapies that remain efficacious over time

Keywords: Biology.
Advisor: Petrov Dmitri Alex
Egan Elizabeth S.
Mordecai Erin
Pritchard Jonathan (Jonathan K.)
Ex vivo expanded allogeneic iNKT cells as adoptive immunotherapy for cancer

Immunotherapy using the adoptive transfer of selected cell populations is a promising approach to treat hematologic malignancies. Further, this approach may have merit in combination with hematopoietic stem cell transplant (HSCT), which is an established therapy, though with some limitations, such as cancer relapse and graft-versus-host disease (GVHD). Invariant natural killer T (iNKT) cells are a subset of innate lymphocytes with antitumor effects and immunoregulatory properties yet without GVHD induction potential. Preclinical studies have demonstrated that iNKT cell expansion and proliferation upon adoptive transfer requires cytokine support through signaling induced by cytokines of the gamma-chain family, particularly interleukin-2 (IL-2). In order to investigate the antitumor potential of murine iNKT cells, iNKT cells expanded ex vivo with IL-2 and IL-15 were cultured with a murine lymphoma cell line in vitro as well as tested in a lymphoma tumor model in vivo. While cytotoxicity was observed in vitro, the effects of the iNKT alone were not sufficient to rescue the mice in vivo. Therefore, to potentially enhance the biological activity of iNKT cells, we explored a cytokine-cytokine receptor complex to transduce onto the iNKT cells. The complex consisted of an engineered orthogonal IL-2 receptor-β (ortho-IL-2Rβ) that pairs with an orthogonal IL-2 (ortho-IL-2), which preferentially expands the transduced effector immune cells while avoiding toxicities associated with IL-2 administration. The successful generation of this product establishes the opportunity to investigate the effects of the engineered IL-2 cytokine-cytokine receptor complex on the cytotoxic capacity of iNKT cells. Collectively, these results demonstrate the great potential of iNKT cells to act as an antitumor adoptive transfer therapy.

Keywords:  Department of Biology
Biology
Adoptive Transfer Therapy
Invariant Natural Killer T Cells
Antitumor Potential
Interleukin-2
Transduction
Thesis
Advisor: Negrin Robert
Cyert Martha
Examining personalized feedback as a tool to teach learning strategies

How do we teach learners to use effective cognitive strategies for learning? We tested the efficacy of two instructional methods: (1) providing learners with personalized feedback on strategy effectiveness, and (2) scaffolding learners' strategy use. In a series of online experiments with adults in the United States, we tested whether these instructional methods were effective in teaching a proven memorization strategy. We observe the impact of these instructional methods on learners' beliefs about the target strategy's effectiveness relative to a common lure, learners' choice to enact the strategy, and their resulting performance on a memory quiz. One contribution of this research is a methodological one: we demonstrate the technological affordances of an online learning environment for dynamic delivery of strategy instruction and process-based measurement of strategy choice. In addition, this research sheds light on potential instructional approaches to help learners trust and adopt effective learning strategies, and could have implications for teaching people to choose normatively desirable behaviors more broadly

Keywords: Education.
Advisor: Schwartz Daniel L. 
Landay James A.
Wieman C. E. (Carl Edwin)
Examining Rural Hospital Closures and Their Impact on Mortality Rates in the US

Over the course of the past 10 years, there have been a significant number of hospital closures in rural and urban areas that have changed the landscape of American health care delivery. This paper uses data from 2012 to 2016 to examine the impact those closures have had on mortality outcomes. Particular focus is dedicated to rural hospital closures, due to the already worse mortality rates in rural counties in America as well as the potentially greater impact of closures in these more geographically isolated regions. The study finds that rural hospital closures are associated with a 10.86% increase in mortality due to AMI, and a 8.91% increase in mortality due to stroke. The impact of urban hospital closures is less than half that of rural closures. The study also finds that the share of deaths in rural counties occurring in out-of-county hospitals as well as the share of residential deaths increases in the wake of closure, suggesting that an increased distance to nearest hospital and further barriers to emergency care may be driving this relationship.

Keywords: health care
hospitals
hospital closures
mortality
health outcomes
rural health
health policy
Thesis
Examining the role of microglia in niemann-pick type C

Neurodegenerative diseases are ultimately fatal, complex, age-related diseases of the central nervous system, for which there are no reliable disease-modifying therapies. Multiple parallel lines of study have identified microglia, the immune effectors of the brain, as potential regulators in many neurodegenerative diseases. While the majority of neurodegenerative diseases are restricted to the aging population, genetic defects can illicit similar diseases in children, as is the case for many lysosomal storage diseases. Niemann-Pick Type C (NP-C) is a rare lysosomal storage disease characterized by progressive degeneration of cerebellar Purkinje neurons in childhood and early adolescence. Microglia in NP-C undergo many characteristic neurodegenerative changes including massive lysosomal accumulation and morphological disturbances. Despite this, there is limited research on NP-C microglia and their function in disease progression. In this thesis, we deeply dissect the function of microglia in NP-C. Utilizing RNA-seq, we define a transcriptional signature of microglia over the course of disease progression. We also examine the functional impact of microglia in NP-C. Transplantation of microglia into a naive brain is able to incite a reactive brain environment, a novel finding that shows that microglia actively alter their brain environment and are not latent bystanders

Advisor: Wyss-Coray Anton 
Andreasson Katrin
Monje-Deisseroth Michelle
Wernig Marius
Expanding transitional justice processes to include social and economic justice : the cases of Peru and Colombia

Relying on interview data and analysis of legal archives, this dissertation reconstructs the socio-legal history of the emergence of transitional justice measures addressing Social and Economic Dimensions of Political Violence (SEDPoV)—various forms of inequalities that are root causes, mechanisms, or consequences of internal armed conflicts—in Peru and Colombia. These two case studies suggest that the transitional justice field has increasingly expanded to develop transitional justice models oriented towards social justice outcomes. Additionally, the dissertation provides an analysis of the combination of factors leading to the inclusion of measures addressing SEDPoV in the Colombian and Peruvian transitional justice processes. Although power of local elites, political opportunities such as regime change, social mobilization, and international norm entrepreneurs are also factors fostering the emergence of transitional justice, this dissertation identifies the emergence of domestic transitional justice bureaucracies as a fundamental factor fostering transitional justice measures. My analysis expands our understanding of the determinants of the emergence of transitional justice measures

Keywords: Law JSD.
Advisor: Martinez Jenny S. 
Weiner Allen S. 
Hensler Deborah R.
Expansive care theory : can messages of inspiring expectations and broad regard promote students' identity safety and academic success?

In this dissertation, I present Expansive Care Theory, which suggests that instructors can create conditions for student success by conveying two messages: 1) "I have high expectations for you to learn and grow, and want to support you in that growth" (inspiring expectations) and 2) "I regard you as a full person, with a range of identities, values, and interests" (broad regard). Past work has suggested that students who perceive either one of these messages from their teachers have improved academic performance (e.g., wise feedback and values-affirmation interventions, respectively). However, these messages have rarely been understood in terms of students' perceptions of teacher practices, nor combined under an integrated theoretical framework. In Chapter 1, I review past literature to propose these two messages can alleviate social identity threat and bolster teacher-student relationships, and in combination can create emergent feelings of care and support in the classroom, which in turn improve academic outcomes. In Chapter 2, I present initial evidence that these messages are most effective in improving students' positive expectations of the classroom and teacher when provided in combination. In Chapters 3-5, I focus on broad regard, and suggest that the practices and resources that educators use to engage students may be more effective to the extent that they explicitly convey broad regard to students. In Chapter 3, I show that values affirmation interventions—which ask students to reflect on their values and have been conceptualized as working primarily within students' individual psychology—are enhanced when these activities are framed in terms of teachers' broad regard for students. In Chapter 4, I examine advising relationships in college, and find undergraduate students view advisors as more helpful when they ask broad regard questions about students' lives compared to questions that are more narrowly focused on students' academic success. In Chapter 5, I examine how office hours are represented to college students. I present a novel randomized-controlled intervention and pre-registered replication, finding that when office hours are represented by course instructors in terms of broad regard—as an opportunity for discussing anything on the student's mind and learning about the student's life—first-generation and underrepresented minority students earn higher grades. I conclude with Chapter 6, suggesting future directions to further refine this theory and understand its potential for practical application in educational settings and beyond

Keywords: Crum, Alia degree committee member.
Psychology.
Advisor: Walton Gregory M. (Gregory Mariotti)
Dweck Carol S.
Exploring low-power ubiquitous sensing using RF backscatter

This thesis explores how RF backscatter can serve as an indispensable tool for designing low-power sensor networks. Low-power techniques allow sensors to be deployed where there is insufficient power or communication infrastructure for traditional sensor nodes. RF backscatter communication consumes an order of magnitude less power than even Bluetooth Low Energy. This dissertation presents three projects that advanced the state-of-the-art in sensing systems that harness RF backscatter. The first two projects, FreeRider and BackCam, describe systems that can backscatter commodity WiFi signals. Instead of having to invest in special-purpose transceivers, we can harness WiFi radios that are already ubiquitous. FreeRider is a backscatter communication platform designed to operate on top of existing ISM-band networks, like 802.11 WiFi. BackCam~\cite{backcam} extends this work by adding a camera sensor to the tag and implementing an edge-based control system. Using RF backscatter makes communication cheap, which allows us to push image processing to the edge. The next project, RayTag, demonstrates how pairing backscatter tags with radars makes the target signal 100-10,000x stronger in amplitude compared to the strongest clutter signal. This allows for simultaneous detection and identification of multiple targets, which is useful for a variety of sensing applications. To demonstrate the potential of RayTag, I show that deploying backscatter tags underground can be used to accurately measure soil moisture. Though I focus on the evaluation of sensing soil moisture, RayTag is not a single-purpose sensing system. Rather, RayTag can be used to enhance a number of existing sensing tasks (e.g. localization) or enable entirely new applications. To that end, this thesis also presents detailed evaluations beyond underground contexts, as well as multiple examples of constructing link budgets. This dissertation further explores a renewable power source for underground backscatter tags. Many backscatter communication systems can harvest their operating power via RF, but this is not practical for underground systems because wet soil attenuates RF too much for harvesting circuits to operate. One potential source of energy are microbes in the soil. Microbial fuel cells (MFCs), sometimes also known as mud or soil batteries, accept electrons that are a byproduct of redox reactions catalyzed by electrogenic microbes naturally occurring in soil. This creates a potential difference across the cathode and anode, which provides a low-cost renewable source of power. In the future, this could allow underground backscatter tags to have an indefinite lifetime

Keywords: Electrical Engineering.
Advisor: Katti Sachin
Arbabian Amin 
Winstein Keith