VictorJuiz/thesis huggingface dataset:
Competitive intelligence [electronic resource] : drivers and consequences of executives' attention to competitors in enterprise software
Keywords: Management Science and Engineering.

In this dissertation, I investigate executives' attention to competitors and the implications for firm innovation. Using a hand-collected dataset on competition, innovation, and executive experience in the full population of public U.S. enterprise infrastructure software firms, I examine attention to competitions in three empirical papers. In the first paper, I show that attending to competitors that activate opportunity-based rather than threat-based views of competition has a positive relationship with product innovation. In the second paper, I show that executives are more attentive to competitors at the periphery of an industry when the experience of the executive team amplifies (i.e. mirrors) the experience of the CEO. In the third paper, I use social network analysis to show that personal similarities between CEOs can influence competition between firms. As a whole, my dissertation suggests that executives can be strategic in how they think about competition, with tangible benefits for firm performance.
Computational modeling of the brain [electronic resource] : development, health, and disease
Keywords: Mechanical Engineering.

The brain is our most complex yet least understood organ, and many questions remain as to its development and the intricate relation between form and function. The characteristic wrinkling of the human brain is the result of both biological and mechanical processes during development, so it is crucial to incorporate soft tissue mechanics in our quest to address relevant developmental and medical questions. A major challenge in modeling the mechanical processes that influence brain development is the significant difference between traditional engineering materials and soft, growing biological tissues. In particular, it is not possible to natively model growth, or the addition of mass, using the traditional finite element method. In response to this challenge, this thesis elaborates on the applicability of computational tools and theoretical frameworks to the modeling of soft, growing materials. Combining the theory of finite growth, continuum mechanics, and finite element analysis allows for the incorporation of biological phenomena in FE simulations; helps distinguish between the behavior of soft, growing materials and their stiffer, non-growing counterparts; and enables the quantification of experimental and clinical data for validation. Beyond continuing work on the physiological and pathological development of the brain, these computational and theoretical advances on the modeling of soft, growing materials lead to many possibilities for future work on other soft tissues.
Comrade Companion: Building Veterans' Socio-Emotional Confidence
Keywords: Graduate School of Education
Learning Design &amp; Technology
Veteran Affairs
Socio-Emotional Learning
Traumatic Brain Injury
Post Traumatic Stress Disorder
Thesis

From 2010 to 2015, over 320,000 US troops suffered from traumatic brain injury (TBI), which results in declines in cognitive, behavioral and affective functioning and may be intertwined with post-traumatic stress disorder (PTSD). Comrade Companion is a semi-anonymous, gamified platform that allows collaboration amongst military veterans with mild TBI and PTSD to share and reflect on personal experiences in a peer-to-peer mentorship model. The goal is to address socio-emotional challenges that these military veterans may encounter, to create a supportive community amongst them, and to simultaneously build their personal socio-emotional confidence.
Constitutional Engineering: Studying Promotions and Revocations of Religious Freedom in Thailand
Keywords:  Program in International Relations
international relations
Thailand
constitutions
ethnic conflict
religious freedom
honors thesis
Stanford University
Thesis

Thailand has promulgated twenty constitutions and experienced more coups—eleven successful coups and seven attempted coups—than any other country since its conversion to a parliamentary monarchy in 1932. Does this pattern of coup transitions suggest that constitutional efficacy is weak in Thailand, or have constitutions been written and rewritten with the goal of directing policy? This thesis aims to answer this question through studying promotions and revocations of religious freedom in Thai constitutions. Through analyzing Thailand’s twenty constitutions and studying other observable indicators such as change in GDP and geo-strategic threats, this paper finds that there is no political logic behind promotions and revocations of religious freedom in Thai constitutions, thereby suggesting that constitutional provisions have little or no effect on policy towards religious freedom.
Constructing scattering amplitudes from their formal properties [electronic resource]
Keywords: Physics.

Scattering amplitudes in quantum field theory encode the probability of configurations of incoming and outgoing particles scattering into each other, as well as particle masses and decay rates. Traditionally they have been calculated using Feynman diagrams, but this method generally proves too computationally intensive to allow for the calculation of higher-loop contributions, which are relevant for making predictions in particle physics experiments and to our understanding of quantum field theory itself. As a step in the direction of filling this computational gap, this dissertation presents an improved bootstrap method for computing scattering amplitudes in the planar limit of maximally supersymmetric Yang-Mills theory. This method does away with Feynman diagrams altogether, and instead uses knowledge of the symmetries and analytic properties of scattering amplitudes, in conjunction with an understanding of the mathematical form these amplitudes take in general and special kinematics, to uniquely determine them at high loop orders. In particular, it makes use of the fact that amplitudes in this theory are expressible in terms of generalized polylogarithms for seven and fewer particles. The first part of this dissertation focuses on six-particle kinematics, where previously-unappreciated algebraic constraints on these amplitudes are described that restrict both their double derivatives and their double discontinuities. Alongside previously-understood constraints, these properties are used to uniquely determine all six-particle amplitudes in this theory through five loops. These explicit results are then used to provide analytic and numerical evidence for a recently-conjectured positivity property these amplitudes are thought to have in certain kinematic regions. In the second part of this dissertation, it is shown that these methods straightforwardly generalize to seven-particle kinematics, where they in fact prove to be even more restrictive than in six-particle kinematics. In particular, a smaller set of constraints is shown to be sufficient to determine specific seven-point amplitudes at three and four loops, up to integration constants. While the results presented in this thesis are confined to the planar limit of maximally supersymmetric Yang-Mills theory, these bootstrap methods are expected to prove useful even in theories without supersymmetry.
The consumer's code of virtue [electronic resource]
Keywords: Business.

This dissertation examines how people navigate their consumption environments to maintain an image of themselves as good and virtuous in everyday life. It comprises an introduction, two empirical chapters, and a theoretical chapter. In the introduction, I provide a literature review on the similarities and potential differences between vice and virtue in interpersonal (i.e., moral) and intrapersonal (i.e., traditional self-control) contexts. In Chapter 1, I argue that people are motivated to experience appropriate negative affect in response to negatively valenced moralized stimuli (e.g., a documentary about the effects of bullying). Consequently, consumers are more reluctant to repair their moods by engaging in hedonic consumption after being exposed to negatively valenced moralized (vs. nonmoralized) stimuli. Furthermore, in social media contexts, such as Twitter, people feel more uncomfortable when hedonic, frivolous content follows negative moralized (vs. nonmoralized) content. These findings challenge emotion regulation research on hedonic motivation to increase positive and decrease negative affect, as well as judgment and decision making literature on preferences for sequences of events that improve over time. In Chapter 2, I argue that people can manipulate social norms around them to justify their own behavior. I examine this phenomenon in the context of indulgence. I demonstrate that for indulgent (vs. non-indulgent) consumption, people feel more justified when others match their behavior than when they engage in that behavior alone, and they therefore are more likely to encourage their friends to match their behavior. Chapter 3 addresses the broad set of strategies that consumers use to reduce dissonance when their behavior threatens to violate their code of virtue. I argue that, rather than relying on psychological strategies to reduce dissonance, they can use behavioral strategies to change their circumstances to avoid dissonance altogether. I discuss a variety of such strategies, and organize them in a framework reflecting the degree of self-protection they confer. I provide evidence that these self-protecting strategies can backfire when they are challenged, and that depending on them can be risky and come at a cost.
Contact Engineering n-Type Molybdenum Ditelluride Transistors
Keywords: Pop, Eric
Electrical Engineering
2D Materials
TMDs
MoTe2
Thesis

Atomically-thin transistors based on transition metal dichalcogenides (TMDs) such as MoS2 and WSe2 have demonstrated significant current modulation, moderate carrier mobilities, and high drive currents down to nanometer-scale gate lengths. TMDs are thus becoming a candidate for scaling CMOS to ultra-short, sub-10 nm channels. Of the TMDs, MoTe2 is still largely unexplored, despite that in monolayer thickness (~0.7 nm) it demonstrates a direct optical band gap of ~1.1 eV, nearly identical to that of bulk silicon. This moderate band gap suggests that MoTe2 may be a suitable candidate for low-power CMOS.
However, it is presently difficult to produce n- and p-type transistors from the same type of TMD, which limits their practical applications. This is partly due to lack of stable doping and partly due to strong Femi level pinning at the TMD-metal contacts.
In this work, we investigate contacts to MoTe¬2 transistors with seven different metals from low to high workfunction (Sc, Ag, Ti, Cr, Au, Ni, and Pt) and extract their respective Schottky barriers in a consistent fashion for the first time. We demonstrate that while all bare metals form some type of ambipolar contact to MoTe2, metal-insulator-semiconductor (MIS) contacts with a single layer of hexagonal boron nitride (h-BN) de-pin the Fermi level of the metal contact, allowing us to achieve the first reported unipolar electron current in MoTe2.
To gain insight into the origin of ambipolar contact pinning to MoTe2, we investigate Ag- and Sc-MoTe2 interfaces. We performed X-ray Photoelectron Spectroscopy (XPS) to uncover that AgxTey and ScxTey compounds were forming at the respective interfaces. These interfacial compounds may largely determine the band alignment.
To prevent chemical reactions at the contact and to de-pin the Fermi-level, we formed MIS contacts by transferring a single layer of h-BN between Sc metal and the MoTe2. Sc was chosen due to its low workfunction (~3.5 eV) to provide good alignment to the MoTe2 conduction band. Thus, we achieved unipolar transistor behavior in a 170 nm channel length MoTe2 device, with ~80 μA/µm electron current and ~105 ON/OFF current ratio at 1 V drain bias.
This is an important result because it demonstrates that monolayer h-BN de-pins the Fermi level and affords unipolar behavior in our MIS-contacted MoTe2 transistors. This study furthers our understanding of metal-TMD contacts and demonstrates a practical route for de-pinning the Fermi level and preventing surface reactions, towards selective, unipolar TMD contacts.
The continuous adjoint method for multi-fidelity hypersonic inlet design [electronic resource]
Keywords: Aeronautics and Astronautics.

Hypersonic air-breathing propulsion systems offer greater efficiency through use of atmospheric oxygen rather than on-board compressed oxidizer tanks, for applications including access to space and hypersonic cruise but require significant further development. The high cost of wind tunnel and flight testing motivates the increased use of computer simulations and motivates advancements to these simulation techniques. A number of the challenges remaining in aerospacecraft design and simulation-based design techniques including gradient-based optimization and uncertainty quantification can be addressed by improving on methods of gradient computation. This dissertation focuses on developments towards generalizing a particular method of evaluating sensitivities and gradients (the continuous adjoint method) to a wider range of functions and multi-fidelity flowpath models. The primary contributions of this work are: the development of the continuous adjoint for a generalized outflow-based functional, a framework that utilizes this generalized functional to find the surface sensitivity for objectives defined external to the CFD volume and enabling multi-fidelity flowpath design, a multi-objective adjoint implementation that utilizes the principle of superposition to combine already-implemented functionals, and optimization studies utilizing these methods on a hypersonic inlet modeled using a multi-fidelity flowpath, including a three-dimensional viscous inlet.
Control for high frequency rendering on impedance type haptic devices [electronic resource]
Keywords: Mechanical Engineering.

Robotic haptics is a growing field that uses specially designed robotic devices as force-reflecting, human-computer interfaces in a variety of applications, from 3D modeling and gaming to telerobotic controllers and surgical simulation. While many types of haptic devices have been prototyped and studied, small, back-drivable, desktop devices such as the 3D Systems Phantoms and Force Dimension Omegas are by far the most common due to their commercial availability, relatively low cost, safety, and ease of use. However, stable and accurate rendering of high frequency signals on these impedance type haptic devices remains a challenge. Traditional control techniques rely on digital closed loop position feedback, which is not well suited to handling the high frequencies inherent in rigid contact simulation and the display of vibrations, transients, and textures. Further, the complex high frequency dynamics of the device act to distort and couple high frequency, multi-degree-of-freedom signals. In this dissertation, three control strategies are presented that improve the performance of impedance type devices at high frequencies, particularly during rigid contact simulation. The first utilizes a high bandwidth current loop at the motor amplifier level to add significant impedance to the device by leveraging the motor dynamics. This enables much higher stiffness rigid contacts, but requires a new high-level control framework for practical implementation. The second strategy layers on top of existing controllers and aims to provide a perception of rigid contact by stopping a user's momentum as quickly as possible through use of an impulse-generating switching controller. Finally, distortion and cross-coupling of high frequency signals are improved through a deconvolution-based, multi-DOF haptic device equalizer.
Convolutional Neural Networks for Phase Prediction in Deep Tissue Microscopy
Keywords:  Department of Physics
Adaptive Optics
Artificial Intelligence
Neural Network
Convolutional Neural Network
Guidestar
Thesis

Adaptive optics have the potential to improve the resolution of optical imaging in deep tissue up to the diffraction limit. We study neural networks as a possible tool to help improve the convergence rate of adaptive optics systems by predicting the wavefront phase error from an abberated PSF.
Adaptive optics systems have proved successful in correcting aberrations produced by atmospheric conditions in astronomy imaging. In this setting artificial guide stars and wavefront sensors which can be used to reconstruct spatial phase variation in the signal wavefront. In deep tissue, given a comparable guide star “particle”, wavefront sensors fail to accurately measure phase error due to the highly scattering nature of the tissue. Thus, alternative strategies to optimize the array positions of the deformable mirror are necessary.
It has previously been shown that a stochastic gradient descent method which randomly permutes the degrees of freedom of the mirror can optimize to an improvement of 2-5x peak intensity. However this process is time consuming (necessitating between 600 and 3000 camera integrations to find an optimal array position). We would like to train a neural network to predict phase distortions directly from distorted PSF images.
In this thesis we show a proof of concept by predicting Zernike and Kolmogorov phase screens from corresponding PSF images. We further show that convolutional neural network architectures appear superior to fully-connected neural network architectures in phase prediction. Finally, we demonstrate a system for the mass collection of data to train a neural network based on real biological tissue. This study represents the first research conducted to use neural networks for adaptive optics for microscopy, and the first research to use convolutional neural networks for any type of adaptive optics.
Cortical electrophysiology of human episodic memory [electronic resource]
Keywords: Electrical Engineering.

In any given day, we encounter events or episodes that are more memorable (better encoded) than others. The memorability of a given event can be experimentally measured by the degree of difficulty (speed, confidence, accuracy) in which that episode is brought back to mind (retrieval). Through lesion and animal model studies we have gained a core understanding of what parts of the brain are involved in these behavioral processes. However, the temporal dynamics and cortical spatial specificity of memory encoding and retrieval mechanisms remain a debated topic in neuroscience. Furthermore, much of our knowledge comes from correlational and indirect measures of brain activity. In Chapter 2 of my work, we leveraged direct recordings from the human cortical surface to study memory processes at a spatial and temporal resolution that remains rare in humans. When participants were tasked to recognize previously presented stimuli, we observed a temporal cascade of activity in the left parietal region of the brain. The intraparietal sulcus (IPS) traverses the parietal lobe and shows greater activity for previously seen items starting ~300ms after probe onset and returns to baseline 200ms before a memory decision is made. On the other hand, a more dorsal region, the superior parietal lobe (SPL), while initially active for both old and new stimuli, remains active through the behavioral response only for new stimuli. These observed cortical temporal dynamics advance theoretical models of the different roles of these parietal regions in remembering. In Chapter 3 of my work, I focused on investigating the causal role of oscillatory activity in the cortex for memory formation. A prevalent theory posits that opposing phases of the theta rhythm should promote states of optimal encoding or retrieval. However, direct evidence for these theorized effects remains scarce. In my work, we induced the theta rhythm in the dorsal prefrontal cortex through transcranial alternating current stimulation. Employing a closed-loop protocol, to-be-learned stimuli were presented at specific phases of the stimulated theta oscillation. Memory for the presented stimuli was later probed, and we analyzed remembered and forgotten stimuli as a function of encoding stimulation phase. Consistent with the theory, we found that memory strength is modulated by phase, such that stronger memories are aligned to
Counting the Czars: Extra-Bureaucratic Appointees in American Foreign Policy
Keywords: Center for International Security and Cooperation
bureaucratic politics
the presidency
foreign policy
Thesis

Though the term “White House Czar” has been frequently used in popular media to refer to any high-level executive branch official created outside the regular bureaucracy, the title has rarely been treated with analytic precision, nor connected to the broader literature on presidential power. “Czars” have now been part of the American political system for a century. However, there has been little scholarship seeking to explain when and why presidents resort to them, particularly in foreign affairs. This thesis seeks to fill the gap, examining three potential factors that could explain the patterns of czar creation over the past hundred years: presidential management style, opposition party control of the Senate (divided government), and the external threat environment that presidents confront. I find that while a competitive management style does potentially increase the number of czars a president appoints, there exists little evidence that divided government drives a president to work outside the standard bureaucratic process. I also find that the specific cause that drives czar proliferation more than any other is fighting simultaneous wars, as was the case during World War Two and after 9/11. This finding suggests that President Trump and his successors will utilize these extra- bureaucratic appointments to implement foreign policy primarily based on their management style and the nature of the problems they encounter, regardless of congressional opposition. It also suggests that further research should be conducted to explore the efficacy of these czars, as they are likely to remain a source of controversy and influence well into the future.