VictorJuiz/thesis huggingface dataset:
Water quality in dynamic redox environments : coupled hydrologic-biogeochemical controls on metal contaminant mobility

Rising population and changing climate threaten to amplify the risks posed by metal contaminants to our freshwater resources. Altered hydrologic cycles and increased demand for freshwater will shift biogeochemical conditions in soils and sediments, potentially transforming metal contaminants from stationary (solid) phases to mobile forms, which are subject to transport and human consumption. Often, redox processes control partitioning of metal contaminants, whether by changing the redox state of the metal itself, or by transforming the metal host(s). In soils and sediments, these redox processes are commonly driven by hydrologic conditions. My research seeks to understand how redox-associated biogeochemical processes arising from and coupled to hydrologic conditions impact metal contaminant partitioning and mobilization. I employ a combination of experimental, spectroscopic, field and modeling approaches to study the partitioning of U, Pb and Cd to solid and dissolved phases in dynamic redox environments. In my first chapter, I find that the calcium-uranyl-carbonato species kinetically limit U(VI) reduction by Fe(II)(aq), thereby impeding transformation of U from a soluble form to an insoluble form. In my second chapter, I show that the stability of Pb in a range of bonding environments limits dissolved Pb concentrations in contaminated floodplain sediments, despite redox-driven dissolution of Pb hosts. In my third chapter, I reveal that soil redox conditions influence the metal-binding properties of dissolved organic matter, leading to increased complexation of Cd by soft ligands in reduced environments. Finally, in my fourth chapter, I find that the impacts of beaver dams on hyporheic biogeochemical activity dwarfs that of seasonal hydrologic dynamics. Overall, my work both furthers our understanding of the biogeochemical cycles of U, Pb, and Cd and deepens our understanding of how changes in hydrology couple with biogeochemical redox processes to determine water quality

Keywords: Earth System Science.
Advisor: Fendorf Scott
Francis Christopher
Nico Peter
Waves, turbulence, mud, and worms : sediment transport and boundary layer dynamics in an estuary

Cohesive sediment transport is a ubiquitous geophysical process that affects coastal erosion management and the prediction of nutrient and contaminant fluxes in the environment. These phenomena are often simulated in numerical sediment transport models, but fundamental questions remain regarding how to best parameterize the small-scale physical processes that cause, and result from, erosion of cohesive sediment from the bed. This research leverages advances in acoustic Doppler velocimetry to elucidate (a) the combined role of waves and currents in exerting stresses on a sediment bed, (b) the erosive response to those stresses, and (c) the feedback effects on the flow in the form of sediment-induced stratification. These analyses are based on data collected during three one-month-long field deployments on the shallow shoals of South San Francisco Bay. From those observations, we found that biological roughness elements protruding from the sediment bed resulted in a mean velocity profile qualitatively similar to that found in canopy shear mixing layers. The near-bed momentum flux was often dominated by a wave component, which was generated by interactions between the wavy flow and the rough bed. This enhanced roughness was capable of increasing the bottom drag coefficient by up to a factor of three relative to measurements over smoother sediment beds. In terms of erosion, we found that waves were much more effective than tidal turbulence at eroding sediment, though this varied depending on the relative water depth and extent of bed armoring. Finally, we found that sediment-induced stratification could reduce bottom drag by suppressing near-bed turbulent momentum fluxes, though turbulent sediment fluxes remained unaffected. In summary, this work presents a novel view of the governing physical processes at the sediment-water interface, and the results can be applied towards parameterizing boundary layer dynamics and erosion in numerical sediment transport models

Advisor: Monismith Stephen Gene 
Fringer Oliver B. (Oliver Bartlett) 
Koseff Jeffrey Russell
“We all have our feet in the same Basque soil”: The Depoliticization of Basque Cuisine in American Media from 1980-2010

The Basque Country in Spain rose to global prominence in the post-Franco area for two very different reasons: for its culinary explosion and excellence and for the terrorist activities of the Basque separatist group, E.T.A. American media covered both movements, but used divergent rhetorical methods to do so, effectively creating two versions of the Basque Country in the American imagination: one highly political, and one seemingly apolitical, sometimes even appearing just pages apart from each other. However, previous research has found that food served as a vehicle by which to preserve Basque nationalism in the face of Franco’s oppression, as food is deeply embedded in and important to the Basque culture. Through this research, I seek to answer the question of how this sharp line between culture and politics was created in American media, exploring how journalism, especially related to food and travel, handles times political strife in areas that are otherwise alluring to their audience. Through a content analysis of newspaper articles from major American media outlets from 1980-2010, I found that the rhetorical methods used by the American media effectively depoliticized Basque food and culture, ensuring that the political tension never complicated the cultural appeal, despite the centrality of Basque culture in the political struggle. Each decade accomplished this through strategies that built on the previous: first, by rigorous separation of food and politics, then by focusing on worldwide cultural markers to overshadow any mentions of politics, and finally, by using the voice of Basque chefs to cultivate the image of the apolitical Basque person. This resulted in an incomplete picture and understanding of the Basque Country from either perspective.

Keywords: Science Technology and Society
Basque
media
Basque cuisine
food journalism
travel journalism
content analysis
Thesis
Advisor: Mullaney Thomas
Wearable multi-analyte sweat sensor and novel sweat rate sensor using novel resonance-based static pressure piezoelectronic sensor

Personalized Medicine is the future of health care and requires continuous monitoring of various physiological parameters for making medical decisions. Sweat is an important means of non-invasive continuous monitoring of such physiologically important molecules and proteins. In this thesis, I present technologies which are significant steps in the making of a wearable sweat measuring device which can work on a population. I present three technologies: 1. A wearable sweat sensing platform which allows non-invasive real-time monitoring of glucose, lactate, sodium and potassium in sweat and skin temperature. 2. A novel sweat rate sensor based on hygroscopic amplification and piezoelectric transduction and 3. Novel Piezoelectric static pressure sensors based on resonance which are used in the sweat rate sensor. Typically, piezoelectric sensors are said to not be able to measure static pressures, but here I demonstrate that it is possible using resonance coupling

Keywords: Electrical Engineering.
Advisor: Davis Ronald W.
Horowitz Mark (Mark Alan)
Howe Roger Thomas
The welfare Eeffects of macroeconomic trends in markdowns and technology

This dissertation consists of three essays on market power and technology. The first chapter assesses how changes in market power and technology have contributed to the decline of the share of national income paid out to workers. In particular, I jointly quantify the impact of markups, markdowns, and technology on the decline of the German labor share. I find that markdowns have steepened significantly over the last two decades. The estimated markdown trend explains more than half of the observed decline of the German labor share. A downward trend in the production elasticity of labor, consistent with factor substitution away from labor, accounts for the remainder. I find that markups have remained stable over the last two decades. I assess the welfare consequences of the observed markdown trend using a heterogeneous firm general equilibrium model. I find that the growing markdown wedge has been associated with consumption equivalent welfare losses of 2.9%. The second essay examines the economic implications of one particular technology, namely the technology to sell goods and services online. This chapter is jointly written with Liran Einav, Pete Klenow, Ben Klopack, Jon Levin, Larry Levin and Wayne Best. E-commerce represents a rapidly growing share of consumer spending in the U.S. We use transaction-level data on credit and debit cards from Visa, Inc. between 2007 and 2017 to quantify the resulting consumer surplus. We estimate that e-commerce spending reached 8% of consumption by 2017, yielding consumers the equivalent of a 1% permanent boost to their consumption, or over $1,000 per household per year. While some of the gains arose from avoiding travel costs of buying from local merchants, most of the gains stemmed from substituting to merchants available online but not locally. Higher income cardholders gained more, as did consumers in more densely populated counties. The third essay contributes to the methodological literature on the estimation of production technology. I assess the identification of Cobb-Douglas production functions in the presence of cross-sectional input price heterogeneity. I show that identification depends crucially on i) whether input prices are observed and ii) whether firms are price takers in the input market. I derive sufficient conditions for identification in the different environments and discuss when prices and lagged quantities are valid instruments. I find that lagged input quantities are generally not valid instruments for current quantities, even in the presence of cross-sectional price variation. Identification is especially challenging when prices are not observed, but can be restored if the exact input price process is known

Keywords: Economics.
Advisor: Klenow Peter J.
Bloom Nick
Einav Liran
"What do you wonder?" Developing and exploring the construct of teacher-curiosity about young children's mathematical thinking

Much research on mathematics teaching views the teacher as inquiring into students' thinking. It is therefore important to understand teachers' curiosity, which may guide such inquiry. This study develops a novel conceptual framework of teacher-curiosity, which is applied to a professional learning intervention for in-service TK-1 teachers, focusing on the early math activity of Counting Collections. Following the intervention participants expressed a greater desire to learn about student thinking, and their reflections helped identify multiple aspects of practice on which teacher-curiosity may have an effect. These findings suggest that teacher-curiosity may provide a generative lens for research and teacher-education to support teachers' inquiry

Keywords: Education.
Advisor: Stipek Deborah J.
Borko Hilda 
Callan Eamonn 
Langer-Osuna Jennifer
What is to be Done? A Landscape Analysis of Fintech Policy in Vietnam

Vietnam's economy is booming. Similar to most other ASEAN nations, the majority of the population of Vietnam is still unbanked. Trying to tackle this problem, Vietnam’s FinTech industry is on the rise due to strong economic growth, rising banking penetration, and increasing internet and smartphone users. The Vietnamese government has issued regulatory initiatives to foster its FinTech ecosystem and promote a cashless society. Despite such regulatory developments, the field of FinTech does not have a full legal framework. The ambiguity, lack of transparency, and especially contradiction among different legal regulations limit FinTech growth. In order to shed light on the potential impacts of ambiguity of FinTech regulation in Vietnam's emerging market economy, this paper conducts a landscape analysis of current FinTech policy with a focus on electronic payments and lending areas. Additionally, this paper provides insights into how FinTech startup companies are currently being regulated and discusses strategies that the government might wish to pursue going forward. The growing FinTech scene in Vietnam is playing a dominant role in economic development. A deeper understanding of the role of FinTech policy frameworks can be useful to government officials, investors, financial institutions, and FinTech startup founders.

Keywords:  Public Policy Program
Stanford University
Humanities and Sciences
Public Policy Program
FinTech
Policy
Regulation
E-payments
P2P Lending
Vietnam
Thesis
Advisor: Duffie Darrell
When Legislation Isn't Enough: How Systemic Underfunding and State Sanctioned Impunity Allow High Rates of Violence Against Women and Feminicide to Continue in Brazil

In the last few decades, feminist activists and women’s rights advocates have gained much ground in the effort to combat violence against women. Significant conventions for women’s rights have been widely adopted and ratified by their target states, such as the United Nation’s Convention on the Elimination of All Forms of Discrimination Against Women and the Organization of American States’ Inter-American Convention on the Prevention, Punishment, and Eradication of Violence Against Women. Despite ratifying both conventions, it took the Brazilian government many years and a conviction by the Inter-American Commission on Human Rights to finally act on its commitments. In 2006, Brazil passed the Maria da Penha Law on Domestic and Family Violence, which typified the many forms this violence could take and created comprehensive mechanisms for its reduction and prevention. Then, in 2015, Brazil passed the Feminicide Law, which defined feminicide for the first time and recognized it as a heinous crime, consequently increasing sentences for perpetrators. Notwithstanding its adoption of such comprehensive and elaborate legislation, rates of violence against women, particularly domestic violence and feminicide, remain alarmingly high throughout Brazil. This work argues that the Brazilian State is complicit in the continued violation of women’s human rights in the country. Through its systemic underfunding and defunding of violence against women programs and organizations as well as the sanctioned culture of impunity that it creates through this underfunding, the State allows and perpetuates violence against women within Brazil.

Keywords: violence against women
feminicide
femicide
gender-based violence
CEDAW
Belém do Pará Convention
Maria da Penha
Brazil
impunity
underfunding
government
Stanford University
Center for Latin American Studies
Thesis
Where have all the coups gone?

Between 1960-1980, the world saw at least ten coups a year, but today coups are extremely rare, shocking events. Why have military coups been facing a global decline? While a rich existing literature on civil-military relations provides numerous explanations for why hostilities might arise between a government and its military, these studies fail to account for why there might be changes over time. Using a multi-methods approach, my dissertation examines how both international and domestic factors explain this dramatic change. I begin by drawing on findings from the existing coup literature to explore conventional explanations for this phenomenon. Conventional explanations are those that might plausibly explain the decline given what is already known about the conditions that lead to coups. These include hypotheses pertaining to the end of the Cold War, democratization, decolonization, and coup-proofing. Upon demonstrating that these conventional explanations are insufficient for explaining the global temporal trend, I introduce two original theories. I first examine changes to covert intervention via coups by the United States and the Soviet Union during the Cold War and argue that both major powers' decisions to move away from supporting coups in part explain the decline. Second, I look at how changes in the domestic political system and civil-military relations has led to changes in the manner by which autocrats exit from office — away from coups and in favor of negotiated settlements with the military and other elites. These findings taken together suggest that the decline in coups does not necessarily indicate improved civil-military relations

Keywords: Political Science.
Advisor: Fearon James D.
Haber Stephen H.
Schultz Kenneth
Tomz Michael
Who “Speaks” For Autism and Who is “M[I]SS[I]NG”? Examining Autism Narratives and Advocacy in the Era of Genomics

Autism spectrum disorder (ASD) is a neuropsychiatric diagnosis defined by social and behavioral traits. The geneticization of ASD is connected to the historical developments of advocacy and biotechnology that collectively led up to the present era of autism genomics in the United States. Divisions within the autism community have evolved from the vast diversity of the autistic experience, including the emergence of the Neurodiversity movement spearheaded by self-advocates challenging autism genomics research and neurotypical representations of autism. This thesis addresses two key questions: (1) How do non-autistic persons develop their lived experiences into “autism narratives” that inform their understanding of autism as a medical impairment and/or personal identity? (2) How do these autism narratives shape their perceptions of autism genomics and neurodiversity? To collect primary data to construct these narratives, I conducted semi-structured interviews with individuals occupying at least one of three roles in the autism community: researchers, family members, and/or service professionals (n = 14). Data were thematically analyzed using the analytic frameworks offered from James Baldwin’s insights on identity, representation, and privilege, which I call “reflexivity.” This thesis builds upon scholarship in medical anthropology, disability studies, and science and technology studies to conceptualize autism advocacy and autism genomics research. Autism narratives form spectrums of their own, reflecting neurotypical participants’ views on the perceived utility of autism genomics research as well as their experiences occupying specific personal and professional roles in the autism community. Furthermore, autism narratives create spaces positioned between the social and medical models of disability by operating at the junctions of precision medicine, medical needs, and social perceptions.

Keywords: Science Technology and Society
Disability
Autism
Narrative
Precision Medicine
Medical Anthropology
Disability Studies
Autism Genomics
Autism Genetics
Autism Advocacy
Autism Representation
Thesis
Advisor: Fullwiley Duana
Sato Kyoko
Wireless control of small electronic tags using air-coupled ultrasound

In the more than 130 years since the first experimental confirmation of radiofrequency (RF) electromagnetic waves, RF waves have been used with increasing effectiveness to improve wireless connectivity. In fact, the total number of wirelessly connected devices is now greater than the total human population, suggesting that people-to-people connectivity is no longer the chief driver of advances in wireless systems. Instead, there is now an assortment of niche applications that, when combined, are going to be increasingly important if the upward trend in the number of wireless systems is to continue into the trillions of devices. To enable this trend to continue, the design of wireless devices will need to be fundamentally rethought; there will need to be a new class of devices that are centimeter-sized or smaller, wirelessly controlled, and either rechargeable or battery-free. In this work, we present the use of air-coupled ultrasound for the control of small wireless devices that meet the criteria given above. The primary advantages of ultrasound over RF derive from its low wave speed in air (allowing operation at low frequencies and small wavelengths simultaneously), while secondary advantages stem from how the emission of ultrasound is regulated (a single intensity limit without transmitter power or gain restrictions). We describe three proof-of-concept projects in which we have leveraged these advantages to build state-of-the-art wireless systems. Common to these projects is the use of a millimeter-sized charge-biased ultrasonic transducer first reported in 2012 that allows for self-sufficient high-sensitivity operation in a small form factor. The first project we describe is an exploration of ultrasonic wireless power delivery to millimeter-sized tags. Our simulation-based case study, validated by measurements of wireless power recovery, shows that ultrasound is effective for transferring small amounts of power to small tags out to several meters away from a reader. Next, we detail the design of our ultrasonic wake-up receiver, which leverages a custom CMOS chip to achieve competitive sensitivity and power consumption while having the smallest footprint among all published RF and acoustic solutions. Finally, we present our work on the combined use of RF and ultrasound for the localization of small, battery-free tags; measurements with a proof-of-concept system show sub-decimeter accuracy out to several meters away from a reader, with future work predicted to achieve sub-cm accuracy for cm-sized tags over the same range. Overall, this work demonstrates that air-coupled ultrasound can be effectively harnessed to move toward a trillion-device reality

Keywords: Electrical Engineering.
Advisor: Arbabian Amin 
Khuri-Yakub Butrus T.
Lee Thomas H.
X-ray spectroscopy of dilute metalloproteins with a transition-edge sensor

Proteins are some of the most complex and finely tuned molecules found in chemistry, responsible for critical tasks such as oxygen delivery, photosynthesis, or nitrogen fixation in cells. Although proteins are mostly composed of hydrogen, carbon, nitrogen, and oxygen, the active site is often a metal. Hemoglobin, responsible for carrying oxygen to the cells, utilizes iron to bond to O2. In order to understand these proteins, it is critical to understand the behavior of the bonding electrons of the metal center. Core-level X-ray spectroscopy is a set of techniques that can yield deep insight into electronic structure. By exciting electrons to the unoccupied orbitals, we can probe the oxidation state, symmetry, and spin of a target element. However, for the most important proteins, the signal of interest is faint, and the samples prone to damage upon exposure to X-rays. New instruments are required that can collect data more quickly and with less noise, so that proteins and other challenging samples can be measured. In this thesis, I present the development of a new instrument for X-ray spectroscopy at the Stanford Synchrotron Radiation Lightsource (SSRL), based on superconducting transition-edge sensors (TES). First, I will describe the capabilities of this detector, and show that it fills a substantial gap in the experimental capabilities of present X-ray instruments. Then I will detail a series of X-ray spectroscopy experiments that I performed with the TES. Using this instrument, I measured both extremely dilute and extremely damage-sensitive samples. This experience allowed us to obtain the first undamaged soft X-ray spectrum of oxyhemoglobin. This spectrum has allowed us to constrain the electronic structure of hemoglobin. Finally, I describe future instruments that will make such measurements more routine

Keywords: Physics.
Advisor: Irwin Kent
Church Sarah Elizabeth
Gaffney Kelly