VictorJuiz/thesis huggingface dataset:
A Scarlet letter? [electronic resource] : institutional messages about academic probation can, but need not, elicit shame and stigma
Keywords: Education.

An important institutional and societal dilemma is how to notify people when they are not meeting performance standards, such as in placing people on a probationary status at school or work. A critical and underappreciated aspect of this dilemma, this dissertation suggests, is that people commonly understand themselves to be in relation with valued institutions that structure their lives. Notification that one is not meeting standards, especially when the notification comes from a valued institution itself, may place this relationship at risk. Insofar as the relationship is valued and experienced as a sense of belonging, notification may lead people to feel ashamed, be concerned that they are stigmatized, and ultimately withdraw from the context, even when that is not adaptive and not what institutional actors intend. Across nine studies, I examine these processes within the context of college students being placed on academic probation. College administrators overwhelmingly reported that they intend probation to both inform students of unsatisfactory performance and support them in remedying it. Students readily identified the first intention from typical probation notification letters but not the second. Consistent with the theory that placement on probation functions a threat to a valued relationship, students who had previously been placed on probation described the probation process as characterized by feelings of shame and stigma. They articulated experiencing worries about belonging and devaluation and identified the probation notification letter as a salient aspect of their experience. Is it inevitable that probation notification letters elicit high levels of shame and stigma? No. Across diverse student samples, "psychologically attuned" probation notification letters designed to explicitly address concerns about belonging and devaluation reduced students' feelings of shame, concerns about stigmatization, and intentions to withdraw from college relative to typical probation notification letters. Can psychologically attuned probation letters to also improve students' academic outcomes in addition to their psychological outcomes? A randomized field intervention with five cohorts of students being placed on probation yielded some, but inconsistent, evidence that they may. A design process to develop contextually specific psychologically attuned probation letters is discussed.
The scramble for political order [electronic resource] : state breakdown and armed group proliferation in civil war
Keywords: Political Science.

What explains the proliferation of armed groups during civil wars? Why do some civil wars become more fragmented than others? Many explanations for armed group fragmentation focus on characteristics of populations or armed groups themselves. In this dissertation I argue for the central importance of another variable: the strength of the state. All civil wars entail the loss of a state's monopoly on violence, but states can lose that monopoly in various ways. Variation in state strength across these different pathways into civil war largely determines the opportunity structure within which armed groups mobilize, and ultimately shapes the degree of fragmentation. State breakdowns—which encompass political paralysis and the collapse of security—are engines of fragmentation, and have a distinct logic from insurgency or conventional separatist wars. I develop and test aspects of the theory in three empirical sections. First, I explore the dynamics of state breakdown in Syria, leveraging a novel dataset compiled by The Carter Center of more than 3,000 YouTube videos announcing Syrian armed group formations. Second, I study the relationship between autocratic regime failures and armed group appearances in the universe of civil wars from 1946-2016 using the PRIO/UCDP Armed Conflict Dataset (ACD). Third, through a medium-N study of conflict episodes in modern Iraq, I contrast cases of state breakdown with cases of insurgency and conventional war.
Sculpting the electromagnetic spectrum for enhanced renewable energy generation [electronic resource]
Keywords: Applied Physics.

In two hours, the sun delivers enough energy to the earth to meet global needs for an entire year. But there's a catch: sunlight is distributed over a broad spectrum of frequencies. This poses a significant challenge for harvesting solar energy because most photovoltaic devices operate with high efficiency only over a narrow band of frequencies. As a result, high-energy sunlight is inefficiently used while low-energy sunlight isn't used at all! Indeed, this 'spectral mismatch' problem is the primary reason single-junction photovoltaic cells are fundamentally limited to efficiencies around 33%. In this thesis, I will describe ways to sculpt the electromagnetic spectrum so that we can make better use of traditionally wasted frequencies of light. First, I'll describe our model of spectral upconverters, materials that absorb unused low-energy photons and re-radiate high-energy photons back to a solar cell. Using a detailed balance analysis, these materials have been shown to increase maximum single-junction solar cell efficiencies from 33% to over 44%. We show that existing upconverters, which are limited by low efficiencies and narrow absorption bandwidths, can yield only marginal (< 0.5%) increases in cell efficiency. However, if the upconversion efficiency of these materials is improved, they could increase cell efficiencies by a few absolute percent, potentially enabling single-junction solar cells with efficiencies exceeding 30%. To this end, I'll describe the first experimental realization of a hot-carrier-mediated upconverter, capable of enabling high-efficiency solar upconversion in a tunable, solid-state device. Then, I'll shift to thermophotovoltaics, a technology that can harvest both excessively low- and high-energy solar photons, as well as capture waste heat from combustion and other existing high-temperature processes. Thermophotovoltaic systems rely on thermal emitter materials that need to retain good optical properties while operating at high temperatures, sometimes in excess of 1200 degrees C. However, the optical properties of most candidate emitter materials have not even been studied in this temperature range. To address this, I'll present work on the scalable fabrication of a promising refractory material: titanium nitride. Using a modified CMOS-industry-standard plasma-enhanced atomic layer deposition process, we demonstrate titanium nitride films and nanoparticles with a strong plasmonic response in the visible and near-infrared. Finally, I'll discuss how we use our custom-built ellipsometry setup to perform in-situ measurements of the temperature-dependent permittivity of titanium nitride, from 21 degrees C up to over 1200 degrees C. I'll describe how the optical permittivity, crystal structure, chemical composition, and surface morphology respond to these extreme conditions, demonstrating a highly robust thermal emitter material that may provide a foundation for next-generation renewable energy technologies.
Search of new physics with boosted higgs boson in hadronic final states with ATLAS detector [electronic resource]
Keywords: Physics.

The discovery of a Higgs boson at the Large Hadron Collider (LHC) confirms the validity of the Standard Model (SM) in the description of particle interactions at electroweak scale. However, radioactive corrections to the Higgs mass drives its value to the model's validity limit, indicating either extreme fine-tuning or the presence of new physics at higher energy scale. Since 2015, the LHC starts its Run 2 journey with unprecedented center of mass energy of 13 TeV. Along with increase in luminosity, this greatly extends the sensitivity of ATLAS experiment to heavy new particles at TeV scale. In particular, many new physics models beyond the Standard Model manifest themselves through significant coupling to the Higgs boson in decays of new particles to a Higgs boson and other SM particles. In this work, two searches for resonances decaying to either pair of Higgs bosons or a Higgs boson associated with another SM vector boson in all hadronic final states are presented using data collected by ATLAS during Run 2. Due to the heavy mass of new resonance, Higgs boson and W/Z boson can be boosted to large momentum, causing their decay products to be collimated. The dominant H-> bb decay mode also provides a clear signature through displaced vertices. A powerful boosted boson identification technique fully exploiting such jet substructure and heavy flavor information is therefore developed and used in both searches to suppress the dominant multijet backgrounds and largely enhance search sensitivity in particular for very high resonance mass. In the absence of significant excess, new exclusion limits are set on benchmark new physics models.
Seismic rotational data [electronic resource] : acquisition, processing and applications
Keywords: Geophysics.

Ground rotations as a result of seismic energy propagation are one of the least studied phenomena in seismology, despite the fact that medium rotations are inherent to elastic continuum theory, and have been known to exist for as long as seismic measurements have been made. However, the industry acquisition standard is to measure three components of translation on land, pressure in water, or both translations and pressure on the ocean bottom. There is no industry standard sensor that records seismic rotations. In this thesis I show how to add rotational data to the traditional seismic processing workflow. I conduct a field survey to show that rotations can be recorded using magnetometers. I combine translational and rotational land data and show that the integrated data can be used to separate wave modes, and thus attenuate strong surface wave modes that obscure reflection data. I also use a machine learning algorithm to automatically identify particular wave modes in combined translational and rotational data, and show that the rotations provide added features to the data which facilitate wavemode determination.
Seismotectonics of the central United States and probabilistic assessment of injection induced earthquakes [electronic resource]
Keywords: Geophysics.

I explore geomechanics of faults and fractures in the central United States. In chapter 2 I show the significant increase in earthquakes in Oklahoma, and it's relationship with saltwater disposal operations. I hypothesize that increased fluid pressure from injection unclamps Oklahoma faults. In chapter 3, I probabilistically explore the known faults in Oklahoma and assuming a pressure perturbation on each, I evaluate the probability of induced fault slip, given uncertainties in mechanics constrained from moment tensor inversion and confirmed with wellbore stress indicators. The result is a traffic light colored fault map. In chapter 4, this hypothesis is generalized into a graphical user interface and probabilistic geomechanics are combined with a radial flow hydrologic model to evaluate the probability that a known fault might exceed coulomb slip criteria. Chapter 5 moves away from induced seismicity to constrain stresses and look at natural fractures in the Piceance Basin, Colorado, exploring the potential for deviated drilling in the Mesaverde section, but fails to add to the case that this is warranted. Chapter 6 applies ambient noise tomography to the central and eastern US, exploring velocity and attenuation around the New Madrid fault zone.
Sense of motion [electronic resource] : tactile sensing for robotic locomotion
Keywords: Mechanical Engineering.

This thesis explores the design and use of tactile sensors to enable small mobile robots to better understand the world on which they are walking, running, and climbing. Our goal is to extend the capabilities of small, mobile robotic systems through the development and application of low-cost, light-weight, robust tactile sensors capable of measuring dynamic contact events and forces associated with locomotion. Specifically, we explore capacitive tactile sensor designs that enable the measurement of shear and normal forces with near equal sensitivity and dynamic performance. We demonstrate the use of these sensors on two robotic platforms. The first is a small hexapedal robot with hybrid wheel-legs that interface with a variety of rough outdoor terrains. The second is a miniature robot that uses bio-inspired controllable adhesives to maintain sustained and forceful contact with the world. In both cases we show that feedback from integrated tactile sensors enables these robots to identify key features of the surfaces on which they are traveling, leading to improved mobility and robust behavior.
Sensing and strategies for power distribution system situational awareness [electronic resource]
Keywords: Electrical Engineering.

A major challenge in power systems will be the integration of advanced technologies such as electric vehicles and rooftop photovoltaics. These technologies pose challenges in the system because they lead to highly variable and unpredictable bidirectional power flows. To integrate these technologies successfully, the power distribution systems must have considerable observability and controllability. Complete observability and controllability have been paradigms of the transmission system. Traditionally, power systems observability has relied on standard, synchronized industrial sensing technologies relying on dedicated Supervisory Control and Data Acquisition (SCADA) communication networks. This investment is justified for national security concerns of grid vulnerability. Distribution systems, on the other hand, have had very little investment in sensing and observability below the level of a regional substation. Deploying the transmission system observability paradigm is definitely possible, but is exceedingly expensive due to the sheer number of devices. On the other hand, many new devices and technologies are being deployed at the customer and utility side. Many of these technologies can sense local conditions on the system. Therefore, using the data from such devices along with advanced estimation methods can lead to increased observability. This leads to the overall focus of this dissertation, which addresses a timely and pertinent question: `How can we increase the observability of the distribution system in a cost effective manner?'. To answer this question, this thesis presents the following contributions. (1) A novel sensing modality that dramatically improves the accuracy of low cost line mounted voltage measurements. (2) A framework for distribution system situational awareness, relying on strategically aggregated smart meter forecasts combined with SCADA network data. (3) A family of simple data driven algorithms using this framework for real time network state estimation in the form of topology and outage detection. (4) A generalization of this framework to a larger set of data and applications, resulting in the Department of Energy Sunshot Initiative Supported: Visualization and Analytics for Distributed Energy Resources (VADER) research project.
Sequential color display for highly multiplexed in situ single-molecular detection [electronic resource]
Keywords: Applied Physics.

While much progress in high-throughput measurements of DNA, RNA and proteins has been made in vitro, our understanding of their dynamics within cells and tissues remains limited. By labeling each type of biomolecule with a unique color, in situ single-molecule visualization has allowed researchers to observe spatial context and copy numbers of those molecules within cells. However, utilizing one color per molecule is not enough for achieving a true multiplex analysis, as the number of colors is finite. To overcome this limitation, we developed a low-cost, highly accurate and rapid technology where each target DNA displays a specified color sequence via sequential hybridization of fluorescent DNA probes at several time points. Our sequential-color-display technology can be easily adapted to other DNA-based fluorescent detection methods to achieve highly multiplexed in situ detection of single DNA, RNA, and/or protein molecules in single cells. We were also able to combine our technology with a padlock-probe-based RNA detection method to detect multiple RNA species in situ with a 0.32% misidentification rate. The ability to measure genomic, transcriptional and proteomic variations in this manner may open an avenue to study the medical relevance of intercellular heterogeneity and intracellular molecular interactions. For example, this technique can be adapted to measure progression of cancers where malignant cells interact with nearby non-malignant cells, or diseases where infected or pathogenic cells interact with nearby healthy cells.
Sex-­Typed Facial Cues, Partisanship and Support for Trump
Keywords:  Department of Communication
Sex-typed facial cues
gender
politics
Stanford University Department of Communication
Donald Trump
Thesis

Voters make consequential assessments of politicians based on visual cues. Female Republican politicians are more likely to have stereotypically feminine facial features than their Democratic counterparts, and the relationship is strong enough that respondents can guess the political affiliation of the women with an accuracy that exceeded chance. I predicted that female, Trump-supporting Republicans holding office in 2016 would have the highest average of facial sex-typicality, followed by all female Republican elected officials. My prediction expected that female Democratic elected officials would have the relatively lowest score of sex-typicality. The averages of sex-typicality were suggestive that the hypothesis was correct, but the differences were statistically insignificant.
Should I Stay or Should I Retweet? Pro-ISIS Twitter Communities and Responses to American Decapitation Strategies
Keywords:  Center for International Security and Cooperation
Center for International Security and Cooperation
terrorism
social media
decapitation strategy
Thesis

Over 30,000 foreign fighters have joined the terrorist organization The Islamic State (ISIS). While foreign fighters are not a new phenomenon, many of these men and women were radicalized online over social media platforms. While terrorist organizations are increasingly using platforms such as Twitter and Facebook, the academic research on the topic is limited. This thesis seeks to answer the question: how to do Pro-ISIS communities on Twitter respond to the United States’ decapitation strategy. With a data set of 119,000 tweets, I use Machine Learning and a Naïve Bayes Classifier to examine changes in Jihadist sentiment within the Pro-ISIS Twitter community in the two weeks before and after three American decapitation strikes against ISIS leaders. Ultimately, I found that in cases where the target has a significant social media presence the number of Jihadist tweets within the community increases, whereas in the case where the target has no social media presence there is not a statistically significant difference in the number of Jihadist tweets within the community.
Sieves and iteration rules [electronic resource]
Keywords: Mathematics.

A sieve is a type of inclusion-exclusion inequality that comes up when bounding the size of number theoretic sets of interest. We explore iterative rules for improving sieve-theoretic bounds when the sifting dimension is slightly greater than one. We also prove some asymptotic results for a model problem introduced by Selberg, in which we pretend that all primes have the same size, and prove the NP-completeness of a decision variant of standard sieve-theoretic questions.
Silicon carbide and color center quantum photonics [electronic resource]
Keywords: Applied Physics.

Quantum photonics has demonstrated unprecedented ways of manipulating interaction of light and matter at the nanoscale. Using effects such as confinement of light to subwavelength volumes and the generation of hybridized light-emitter states, one can reduce power and increase speed in optical networks, manipulate quantum information, and sense biological parameters. A preference for narrow emission linewidths and long spin-coherence has drawn special interest to solid-state systems that incorporate color centers. These platforms hold a promise of novel cavity quantum electrodynamical effects, integrated photonics and spintronics. While a majority of color center findings has been obtained using the nitrogen-vacancy center in diamond, recent research efforts have focused on discovering new emitters in wide band gap substrates. Therein, silicon carbide has emerged as a color center host with outstanding optical properties. This thesis presents the development of silicon carbide and hybrid silicon carbide-diamond color center quantum photonic platforms, studied through modeling, nanofabrication, and confocal spectroscopy. This includes our pioneering demonstrations of high quality factor and small mode volume microresonators in cubic silicon carbide (3C-SiC), such as photonic crystal cavities at telecommunication wavelengths and microdisks in the visible and near infra-red. Next, we have developed a scalable and efficient photonic design for spintronics at the single emitter/quantum bit level implemented in hexagonal silicon carbide (4H-SiC). We have also utilized the refractive index similarity between diamond and silicon carbide to enhance silicon-vacancy and chromium center emission in nanodiamond. Finally, the thesis introduces the model of a nanocavity containing multiple color centers that exhibit collective cavity quantum electrodynamical effects, and discuss how this regime could be reached experimentally.
Silicon Valley restaurants innovate solutions for unique economic challenges
Keywords:  Stanford University
restaurant
Silicon Valley
economic pressure
tech companies
innovation
free cafeterias
Thesis

Typical restaurants in Silicon Valley struggle with rising labor costs, labor shortage, rent increases and fierce competitions with tech giants’ free cafeterias.
According to Zillow, a one-bedroom apartment in Silicon Valley costs more than $3,000 in 2017. Likewise, the rental prices for restaurants have been increasing over the years. According to Palo Alto’s Planning Department, the average monthly rental rate for retail in 2015 is roughly $10,000 per month for 2,000 square feet, a 20 percent increase from 2013.
These economic pressures have impacted Mid-Peninsula restaurant owners' ability to hire and retain quality staff. Meanwhile, tech giants like Facebook are hiring away full-service restaurants’ best chefs, line cooks, dishwashers and servers with wages, benefits and incentives that restaurant owners find hard to match.
At a time when costs of living and labor are high in Silicon Valley, some restaurants are trying to use cutting-edge technology and innovations to be successful in one of America’s most difficult restaurant scenes.