VictorJuiz/thesis huggingface dataset:
Ion penetration in conjugated polymers : connecting structural effects and electronic transport

Ionic liquids are increasingly employed as dielectrics to generate high charge densities and enable low-voltage operation with organic semiconductors. However, effects on structure and morphology of the active material are not fully known, particularly for permeable semiconductors such as conjugated polymers, in which ions from the ionic liquid can enter and electrochemically dope the semicrystalline film. To understand when ions enter, where they go, and how they affect the film, thin films of the archetypal semiconducting polymer, poly(3-hexylthiophene) (P3HT), are electrochemically doped with 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([EMIM][TFSI]), the archetypal ionic liquid. High-resolution, ex situ x-ray diffraction measurements and complete pole figures reveal changes with applied voltage, cycling, and frequency in lattice spacing, crystallite orientation, and crystallinity in the bulk and at the buried interface. Dopant ions penetrate the film and enter the crystallites at sufficiently high voltages and low frequencies. Upon infiltrating crystallites, ions permanently expand lamellar stacking and contract pi-stacking. Cycling amplifies these effects, but higher frequencies mitigate the expansion of bulk crystallites as ions are hindered from entering crystallites. Important metrics for electronic transport such as mobility and drain current ON/OFF ratio are also affected following patterns analogous to those seen for lattice spacing and crystallinity under two operating regimes. This mechanistic understanding of the structural effects of ion penetration will help develop models of the frequency and voltage impedance response of electrochemically doped conjugated polymers and advanced electronic applications.

Keywords: Materials Science and Engineering.
Advisor: Salleo Alberto
Appel Eric (Eric Andrew) 
Brongersma Mark L.
It Motivated Me More Than It Crushed Me: Children of Incarcerated Parents in a Highly Selective University

With over 2.7 million American children living with a parent absent to jail or prison, the rampancy of parental incarceration has become an insidious epidemic that disproportionately affects impoverished Black and Hispanic youth. While minimal research has examined these children at the elementary and secondary education levels, there has been no research to date about their experiences in institutions of higher education. In order to address this void and explore how educational systems can better adapt to the circumstances of parental incarceration to facilitate student achievement, this study employed a semi-structured, qualitative research design to examine the perceptions of twelve students with histories of parental incarceration at a highly selective university. Results suggest that the majority of the participants 1. perceived their parents’ incarceration as the impetus for their educational performance; 2. demonstrated an independence that has led to social isolation within educational environments; and 3. used their experiences with parental incarceration and its symptomatic adversities to inform their social impact career aspirations. This study suggests that these students’ narratives and their successes should not be used as models for other children of the incarcerated to strive for. Rather, the analysis reveals what exactly was burdened by these participants in order for them to attain academic excellence and how those burdens can be structurally displaced onto educational institutions. Finally, to begin to rectify the intergenerational effects of parental incarceration, this study suggests that there must be a commitment to addressing the historical sentiment, pervasive in the bedrock of American democracy, that deems poor families of color unworthy of remaining a family unit.

Keywords: parental incarceration
education
higher education
Stanford Graduate School of Education
Comparative Studies in Race and Ethnicty
Thesis
It Was Just Me and the Book: Understanding How Students Navigate the NYC School Choice Process

Although the New York City Public School system is a free choice system on paper, in reality access is limited by the complexity of the school choice process. The resulting inequality is disproportionately borne by low income students of color in New York City neighborhoods who face the sometimes tacit school choice procedures. This research aims to understand the range of experiences of low income Black and Latinx students in New York City in understanding and navigating the public school admissions system. In semi-structured interviews, I questioned seven students about their educational experience of selecting a high school in New York City and how those experiences were shaped by the levels of information or resources that were available to them. I focused on what kind of support the students received in their respective middle schools. Overall I found that students themselves develop a critique of systemic inequities and cultivate strategies for responding to these disparities. Additionally, the term “school choice” is deceptive since many students are unable to exercise choice. Thus, while schools are often popularly imagined as spaces of opportunity for upward socioeconomic mobility, they are in fact deeply reproductive contexts characterized by systematic disparity and exclusion.

Keywords: Graduate School of Education
school choice
New York City education
educational inequality
low income school
student choice
eighth grade
high school
public school
guidance counselor
high school
specialized high school
Thesis
Advisor: Rosa Jonathan Daniel
Jessica Alva was a MMIW advocate. Now she’s their latest rallying cry

Jessica Alva, 35 and mother of six, died on April 6, 2019. Her death has been ruled as a suicide by the San Francisco Office of the Medical Examiner, but her family believes she was a victim of domestic violence resulting in death. Her death is being investigated by the Special Victims Unit of the San Francisco Police Department. Alva is an Indigenous descendent of the Blackfeet and Chickasaw Tribes of the United States, as well as the Aztec and Yaqui Tribes of Mexico. If her family's suspicions are true, her story would be one example of a myriad of cases affections Native American communities known as the Missing and Murdered Indigenous Women (MMIW) movement, where data shows that Native women are being murdered and going missing at disproportionate rates.

Keywords:  Department of Communication
Brenner, R.B.
Stanford Journalism
Missing and Murdered Indigenous Women
MMIW
Thesis
Advisor: Migielicz Geri
Justice and work-family conflict

In recent years, scholars and activists have sought to make workplaces friendlier for employees with family responsibilities. Are such workplace changes requirements of justice, and if so, why? I argue that we should make these changes because lifestyles that mix work and family are valuable, and such lifestyles are harder to come by than they would have been if not for our history of gender injustice. The latter point, I claim, licenses an exception to the general liberal ban on promoting particular lifestyles. This exception is needed to make good on the promise of equal citizenship for women. My argument contrasts with the more familiar one that justifies family-friendly workplace policies because they further the equal representation of women in employment. The familiar argument falls short in two ways. First, there evidence that family-friendly workplace policies sometimes exacerbate the gendered division of labor (because women use them more than men). Secondly, achieving gender proportionality across social roles does not require changing those roles. If there is, in fact, a justice-based rationale for improving the fit between work and family life, we need one that appeals directly to the value of a mixed life and does not piggyback on the also worthy goal of ending the gendered division of labor. That is what I provide in this dissertation.

Keywords: Philosophy.
Advisor: Satz Debra 
Bidadanure Juliana 
Cohen Joshua
Keen to Screen: The European Union Response to Growing Chinese Investment

In March 2019, the European Union adopted a framework for screening foreign direct investments entering the EU. However, the framework fails to grant the European Commission the power to block investments that threaten security or public order, rendering the legislation essentially toothless. Why did the EU decide to pass a toothless regulation on investment screening? This thesis seeks to understand the EU’s motivations for adopting an impotent screening regulation. Using evidence from periodicals, public statements, and interviews with European bureaucrats, this thesis argues that the unparalleled risks associated with Chinese FDI compelled some Member States to push for screening at a European level. With an increasing amount of Chinese investment, particularly in strategic sectors like critical technology and infrastructure, countries like Germany began to comprehend the economic and security threats posed by Chinese FDI. Meanwhile, other states that benefitted from Chinese investment sought to keep Chinese capital flowing and therefore opposed investment screening. Some states also disapproved of screening because they thought this measure was protectionist and antithetical to the EU principle of open markets. To balance these differing stances on Chinese investment, the EU created an empty legislation that would meet the least amount of resistance in a vote. Furthermore, as a volatile turn in transatlantic relations took hold, the EU sought to assert its autonomy from both the rising power of China and its traditional ally the United States. The passage of the screening framework, despite its weaknesses, served as a signal of independence to the international community.

Keywords: Center for International Security and Cooperation
European Union
China
FDI
investment screening
Chinese investment
Thesis
Advisor: Crenshaw Martha
Crombez Christophe
Knowledge inequality

Never before has such a wealth of information been so immediately accessible to so many and yet the filtering demands so high. Information truly is power; who possesses it and wields it most effectively has profound consequences for inequality and human welfare. Are some groups systematically advantaged across all areas of factual knowledge? Or is there a knowledge division of labor, in which some groups specialize in certain areas? Rather surprisingly, we have no systematic accounting of who knows what. My dissertation provides a comprehensive description of knowledge in the United States. To accomplish this, I compiled data on 513 factual knowledge questions from 48 nationally representative surveys fielded between the years 2005 and 2015. The first paper, presented in Chapter 2, explores overall trends in the general knowledge of United States adults in 16 different domains. People know the most about current events and the least about economics. Chapter 3 explores demographic patterns in differential knowledge attainment, providing concrete evidence on the size of knowledge disparities by gender. Social expectations and socialization shape the knowledge acquired by men and women, with dramatic consequences for inequality. Finally, my third paper presents my method BINCONT (the Binned INcome CONtinuous Treatment), which allows researchers to impute estimates of missing binned income data that approximate a continuous distribution. My dissertation analyzes the social ecosystem of knowledge. I investigate many domains of factual knowledge from religion to language to science to war. I evaluate men's and women's command over factual knowledge in a wide variety of domains. I describe the present state of factual knowledge, and I present gendered patterns of inequalities. Overall, the project contributes to the field of knowledge inequality.

Keywords: Sociology.
Advisor: Correll Shelley Joyce 
Grusky David B. 
Burgard Sarah Andrea
Freese Jeremy 
Jackson Michelle Victoria
The Koroghlu epic in trans-imperial perspective : the story of the Ottoman and Safavid expansion and crises

This dissertation examines the epic of Koroghlu ("the blind man's son"), an oral tradition that spread through Eurasian lands during the early modern period. The epic contains a strong critique of imperial power and reflects the rapid imperial expansion of the previous century and the partitioning of Anatolia and Iran between the Ottomans and Safavids. The story also reflects the political, military, and social crises which followed this expansion, and which followed broader global patterns of empires during this era. By first describing the oral and performative manner in which the Koroghlu tradition circulated, along with other epics, and then analyzing the story according to the themes of space, time, and power, this dissertation shows how entangled the lands of Anatolia and Iran were during the early modern period. It also discusses the historical relevance of several important narrative themes in the epic in the 17th century context, including banditry, tribal politics, Turkoman identity, perceptions of Ottoman power, and the geographic notion of Anatolia (or "Rum") and Iran.

Keywords: History.
Advisor: Yaycioglu Ali 
Kollmann Nancy Shields
Rodrigue Aron
Label-free optical detection of bioelectric potentials using electrochromic thin films

Recording electrical signals from cells with electrode arrays is limited by the number of addressable cells, fixed recording sites, and incompatibility with optical tools. Herein, we overcome these limitations by recording field potentials using electrochromism to translate electrical signals into changes in optical absorbance. We use a prism-coupled attenuated total internal reflection laser setup to interrogate the small changes in color by examining the light intensity of a laser beam reflected by the film. We apply this label-free technique to genetically modified cells, human iPSC-derived cardiomyocytes, primary mouse hippocampal neurons, dorsal root ganglion neurons and organotypic hippocampal brain slices. This platform is a powerful method to study electrically active cells which are difficult to transfect since the field of vision can be redirected by stirring the laser onto to the desired region of interest.

Keywords: Chemistry.
Advisor: Cui Bianxiao 
Chidsey Christopher E. D. (Christopher Elisha Dunn)
Martinez Todd J. (Todd Joseph)
Lapsing while learning : how attentional fluctuations hinder memory formation

The human brain has a remarkable capacity for retaining the details of our everyday lives over long stretches of time. Part of what enables this feat is our ability to attend to certain details, while neglecting others. Our ability to stay focused on the world around us also wavers, and lapses of attention can contribute to which experiences we ultimately remember or forget. In this work, we build on decades of research into how attention during memory formation affects long-term outcomes. We do so by complementing a basic science approach with investigation of an emerging societal trend -- media multitasking, or habitually consuming multiple streams of media concurrently. Heavier media multitasking has been associated with an array of cognitive differences, including sustaining and directing attention, and forming short- and long-term memories. In Chapter 2, we leverage functional magnetic resonance imaging (fMRI) to measure the neural impact of distraction and its interactions with memory formation. We find a clear detriment to behavioral measures of memory performance, but neural findings suggest that internal distraction or mind blanking may play an important role as well. Specifically, heavy media multitaskers' poorer memory performance may be driven by a hyperactive "bottom-up" attentional network. Thus, in Chapter 3 we employ pupillometry to index attentional lapsing throughout a battery of sustained attention, working, and long-term memory tasks. We find two distinct patterns in our results: pupillary effects on long-term memory performance are associated with those predicting sustained attention task error rates, and media multitasking-related deficits in working memory performance can be accounted for by baseline pupil differences, response times indicating attentional lapses, and relative deficits in sleep duration. Collectively, these findings support the notion that attentional lapsing contributes to in-the-moment failures to encode experiences into lasting memories. Furthermore, individual differences in the ability to build memories of our everyday lives (such as those tracked by media multitasking) may be largely attributable to these lapses.

Keywords: Psychology.
Advisor: Wagner Anthony David 
Gardner Justin
Poldrack Russell A.
Large-scale neocortical dynamics and information processing underlying a sensory decision

Sensory perception is fundamentally limited by the coding accuracy of sensory neural ensembles. Although a substantial body of work suggests that populations of sensory neurons exhibit correlated fluctuations that may bound the precision of neural coding, the extent to which these fluctuations extend across multiple cortical areas and interact with sensory coding during active animal behavior remain poorly understood. To examine the impact of correlated fluctuations on information coding and communication across sensory cortical areas, we imaged the Ca2+ activity of > 21,000 individual neurons across 11 neocortical areas in mice performing a Go/No-Go visual decision-making task. Multiple neocortical areas accurately encoded the visual stimulus, as well as the animal's decision to respond. Our analysis also revealed positively correlated noise fluctuations across neural populations in multiple neocortical areas. The mean strength of these noise correlations varied as a function of time across the visual stimulus presentation, delay, and response periods of our decision-making assay. Notably, sensory cortical neurons generally exhibited noise fluctuations that were more positively correlated at the start of visual stimulation, but then less so as a decision-making trial proceeded. Our results reveal that 60% of the total power of cortical variability stems from correlated fluctuations of neural populations spanning multiple distinct cortical areas. The strongest cortical fluctuation was a decision-coding activity mode that encompassed all brain areas under observation. We also found several fluctuation modes that encoded visual stimulus information but were shared across fewer brain areas. Overall, our analyses suggest that information regarding sensory stimuli and perceptual decisions are processed and shared between cortical areas through mutually non-interfering orthogonal channels. The timing of informative activity in these channels suggests that sensory information is first processed through intercommunications between multiple sensory areas, followed by a propagation of the final decision to all cortical areas involved.

Keywords: Electrical Engineering.
Advisor: Schnitzer Mark Jacob
El Gamal Abbas A. 
Ganguli Surya
Laser shaping and streaking for x-ray free-electron lasers

Lasers have been a versatile tool in facilitating x-ray free-electron lasers in various components of the machine. At the beginning of photocathode injectors, the properties of the drive laser determine the initial distribution of the electrons. Laser heater has been widely used to modulate electron bunch energy spread in order to suppress collective instabilities arising from dispersive sections in the accelerator. Interaction between optical lasers and the electron beam can be used to manipulate the phase space of the electron bunch to produce desirable shapes in the x-ray emission. After the x-ray photons have been generated, optical lasers are used in synchronization with the x-ray pulse to study dynamics in atomic and molecular systems. Moreover, they can provide single-shot diagnosis of the x-ray pulse, such as laser streaking, to extract valuable information about the x-ray pulse itself and the dynamic system under analysis, which can be challenging to probe directly. In this work we examine laser applications specifically in the Linac Coherent Light Source (LCLS). In the first half of the thesis, we focus on laser shaping techniques applied to the injector drive laser and the laser heater, in both spatial and temporal domains. We further discuss ghost imaging as an application of laser shaping in accelerators and its potential to be used in other x-ray and electron imaging experiments. In the second half, we switch gear to laser streaking as a measurement tool for attosecond x-ray pulses. We discuss in detail the generation of attosecond x-ray pulses at LCLS and present exciting results of the first single-shot characterization of such extremely short pulses using laser streaking.

Keywords: Physics.
Advisor: Huang Zhirong
Bucksbaum Philip H. 
Raubenheimer Tor O.
LEADERSHIP DURING CONFLICT: WHERE CHARISMATIC LEADERSHIP FALLS SHORT

What is effective leadership during crisis? This thesis explores how leaders ought to best handle different forms of crisis, by examining how Elon Musk and Lee Iacocca respectively dealt with the crises at Tesla and Chrysler. Musk’s charismatic leadership, which incorporated narcissistic qualities and an inflated sense of confidence, led him astray when dealing with Tesla’s financial issues and driver fatalities. The public response to Musk’s decisions, as exemplified through stock changes, sheds light on the impact of Musk’s choices during the various crises he dealt with. Iacocca’s transformational leadership, in contrast, helped empower his subordinates to work together to mitigate the dire financial situation at Chrysler. The effectiveness of his approach is examined through production sales. These two case examples shed light on how leadership style influences crisis management, and when they can go wrong. 

Keywords:  Department of Communication
Leadership
conflict
Tesla
Chrysler
Stanford Department of Communications and Journalism
Thesis
Advisor: Pan Jennifer
Learning and exploring the compositional structure of 3D data

3D data arising either from scanning real objects with depth sensors or from modeling by designers have a unique characteristic — they represent the entire geometry of objects in a real world. As such, unlike 2D images containing only a projected view with occlusions and clutter, they directly enable understanding of how the objects are composed and structured in an actual physical space. In this dissertation, we present novel methodologies for learning the compositional structure of 3D data from a collection and study various downstream applications, enabled by this structure extraction. The main contributions are organized into three parts: shape decomposition, structure knowledge aggregation, and shape composition. In the decomposition part, we first discuss ideas for parsing raw scanned 3D data and segmenting them into multiple parts based on either their local geometry or topological structure. For solving the model estimation problems more robustly, we propose frameworks integrating supervised learning and optimization techniques, taking advantage of supervision while guaranteeing local optimality. In the knowledge aggregation part, we consider the case when the compositional structure (e.g., parts or keypoints) given for each 3D shape is inconsistent across the collection due to the difference in data sources. We introduce a neural network that can canonicalize the information defined on independent shapes, without any supervision through correspondences. Lastly, in the composition part, we show how a part-based representation of 3D objects can facilitate shape creation and editing. This representation allows efficient exploration over the shape variation space by fusing a discrete, combinatorial global structure space with a continuous local geometry space. Our methods also learn the part-level structure with unlabeled parts and discover their semantic relations both in a single object and across shapes based on contextual information.

Advisor: Guibas Leonidas J. 
James Doug L. 
Savarese Silvio