VictorJuiz/thesis huggingface dataset:
Experiment sample sizes on influence diagrams [electronic resource]

In many decision situations there are opportunities to gather additional information before making some of the decisions, but the choice of which experiments to conduct with limited resources of time and money can be even less intuitive than the original decision problem. For example, a pharmaceutical company can conduct trials to observe the risks and benefits of new treatments, an oil company can perform seismic studies before drilling wells, or a manufacturer can operate a pilot plant before investing in a new production process. This dissertation explores the available experiments in a decision context and how many of each should be acquired, weighing the costs of the experiments against their potential benefits. The solution methodology developed to answer these research questions is inspired by the preposterior analysis from Raiffa and Schlaifer's seminal "Applied Statistical Decision Theory". They use a Gaussian model to approximate both the decision maker's prior beliefs and likelihood of experimental observations about a single binary uncertainty. This work extends their method to multiple multinomial uncertainties, represented by an influence diagram, for which there can be many different possible experiments. The methodology first considers a general decision problem with finite alternatives and states, a decision maker with constant absolute risk aversion, and a linear sampling cost. Computing the value of experimentation of one uncertain variable in such a problem is at least exponential in the number of states of that variable. Therefore, an approximate expression is derived for the value of experimentation as a function of the number of samples acquired based on a Gaussian approximation to the sample information. Determining an optimal sample size for the approximate value of experimentation is shown to be tractable with numerical methods. The methodology is extended to general finite-prospect influence diagrams containing multiple uncertainties where the decision maker chooses sample sizes for several experiments simultaneously. The resulting approximation for the value of experimentation has similar properties to the single uncertainty case which makes analysis tractable for many practical problems. Policies can be derived for both parallel and sequential experimentation, and they are shown to be close to the exact optimal policies in problems where the exact solutions can be determined.

Keywords: Management Science and Engineering.
Advisor: Shachter Ross D. primary advisor. Thesis advisor
Howard Ronald A. (Ronald Arthur)
Van Roy Benjamin advisor. Thesis advisor
Explaining the unexpected [electronic resource] : sense-making and the perpetuation of gender stereotypes

This project explores individuals' affective motivations to perpetuate macrolevel beliefs. Specifically, I argue that as individuals constantly process and interpret social information, they strive to align their social realities with pre-existing cultural stereotypes in an effort to make sense of the world around them and ensure smooth and seamless social interaction. I refer to this process as sense-making. Using gender as one instantiation of sense-making, I point to two sense-making strategies by which stereotype maintenance occurs in the face of inconsistent information. First, I posit that attribution processes allow individuals to "explain away" stereotype-inconsistent information. Consequently, I argue that successes and failures by low-status individuals (e.g. women) generate different patterns of attributions than do similar successes and failures by high-status individuals (e.g. men). Second, I draw on GSS analysis and in-depth interviews and show how women who hold gender egalitarian ideologies but do not self-identify as feminists are able to reconcile this inconsistent information through the adaptation processes of redefinition and contextualization. I argue that through attribution and adaptation processes, individuals reinstate traditional cultural meanings into their otherwise more progressive social realities. Thus, I suggest that these processes may be partly responsible for the persistence of gender stereotypes despite the significant progress in economic and social realities.

Keywords: Sociology.
Advisor: Correll Shelley Joyce primary advisor. Thesis advisor
Ridgeway Cecilia L. primary advisor. Thesis advisor
Grusky David B. advisor. Thesis advisor
Exploiting speech structure for noise estimation in single channel speech enhancement [electronic resource]

When a speaker's voice is mixed with background noise, the noise can be a nuisance and greatly affect the overall perceived quality and intelligibility of the underlying speech. The ability to enhance noisy speech has strong implications for cell phones, teleconference systems, hearing aids and automatic speech recognition systems. In many applications we are constrained by having only a single microphone input of the noisy speech. Having to estimate the underlying clean speech without additional noise references makes the single channel speech enhancement problem challenging. Most single channel speech enhancement methods (e.g., spectral subtraction, Wiener filter, short time spectral amplitude estimator) require an accurate estimate of the background noise. The majority of prior work on background noise estimation assumes that noise is stationary or at least slowly varying with respect to speech. This, however, makes it difficult to reduce noise in more realistic environments where the background noise is non-stationary. In this dissertation we address two approaches to estimating the background noise by exploiting knowledge on the underlying speech structure. We first present a statistical model that incorporates the harmonic structure in voiced speech. By observing in-between the harmonics of voiced speech, a more accurate estimate of the back- ground noise can be obtained. The second approach trains a dictionary from clean speech to capture the formant structures of speech. The noise is detected using an outlier framework, where the noisy input is compared with an entry in the dictionary. By taking advantage of how the speech is structured, the noise estimate can be updated more promptly, and we can thus reduce the noise under non-stationary and more realistic environments.

Keywords: Electrical Engineering.
Advisor: Smith Julius O. (Julius Orion) primary advisor. Thesis advisor
Widrow Bernard
Schafer Ronald W.
Expression signature-guided functional genomics for gene discovery in non-small cell lung cancer [electronic resource]

Lung cancer is the deadliest cancer worldwide. Survival rates for the most common histological subtype, non-small cell lung cancer (NSCLC), have remained 15% over the past several decades. New molecular understandings and treatments are required to advance NSCLC patient care. Here we use several gene expression-based methods to uncover novel dependencies within NSCLC. First, we use cross-species functional genomics to identify TCEB1 (Elongin C) as a novel synthetic lethal partner with mutant KRAS. Secondly, we use gene expression meta-analysis to identify PTK7 as a survival gene in a subset of lung adenocarcinoma, the major type of NSCLC. Our work demonstrates the utility of analyzing gene expression data sets to expose functionally relevant genes within NSCLC, which may lead to effective therapies.

Advisor: Sweet-Cordero Eric primary advisor. Thesis advisor
Butte Atul J. advisor. Thesis advisor
Giaccia Amato J. advisor. Thesis advisor
Pollack Jonathan D.
Extraordinary power enhancement from nanoaperture vertical cavity surface emitting lasers for near-field applications [electronic resource]

Near-field optical microscopy requires extremely high optical fields in proximity to the object being probed. The high optical field can be use to manipulate objects, make high definition inscriptions in the case of lithography, or to facilitate enzymatic reactions in biological systems. However, when light propagates through conventional circular or square shaped apertures, the power-throughput decays as the fourth power of the aperture size. A vast diversity of unconventionally-shaped apertures are presented. These C-, L-, and bowtie-shaped apertures exhibit extra-ordinary enhancement in both power transmission and near-field intensity that can be one million times greater than the conventional circular- or square-shaped apertures. They can also be iterated into a fractal-structure resulting in many interesting optical properties or can be further enhanced with plasmonic rings. Near-field scanning optical microscope (NSOM) images capable of sub-diffraction-limited resolution were confirmed by the optical near-field spot size. Furthermore, experiments using electron-energy loss spectroscopy (EELS) with sub-nanometer resolution revealed the near-field spot-size and the plasmon energy ranges of the nanoapertures. These unconventional apertures and arrays of apertures were incorporated into vertical cavity surface emitting lasers (VCSELs); this integrated near-field device demonstrated a power density of 50mW/[micrometers]2, five times larger than the power density required for high-density optical recording. Finally, a novel architecture that combines a VCSEL with an NSOM-like tip (VCSEL nanoscope) into an integrated device is presented. The VCSEL nanoscope can serve as a powerful device to manipulate and probe the nanoscale such as single molecule manipulation and detection, high throughput wafer defect detection and near-field coupling to waveguides for optical interconnects.

Keywords: Applied Physics.
Advisor: Harris J. S. (James Stewart)
Byer R. L. (Robert L.)
Vuckovic Jelena advisor. Thesis advisor
Fabrication and electrical properties of topological insulator thin films [electronic resource]

Topological insulators are a special category of materials that are insulating in the bulk but have robust conducting surface states. As an ideal candidate for low power electronics, spintronic and quantum computation, topological insulators have been actively studied both theoretically and experimentally in the past couple of years. To achieve high quality thin films of topological insulators and understand their properties thoroughly is a critical step towards all potential applications. In this dissertation, I will introduce methods to fabricate high quality topological insulator Bi2Se3 thin films using both pulsed laser deposition (PLD) and molecular beam epitaxy (MBE) with a radio frequency (RF) cracker cell. Using PLD, bilayers of topological insulator Bi2Se3 and insulating ferromagnet EuS were fabricated. Weak localization of the surface states was observed at the interface under the Curie temperature of EuS, as a direct evidence of the proximity effect. Using MBE with the RF cracker cell, high quality ultrathin Bi2Se3 films were successfully grown. Analysis of the magneto-resistance of those ultrathin samples measured at low temperature shows both the characteristic weak antilocalization from the surface states and the weak localization from the quantized bulk states, in good agreement with theoretical predictions. With our abilities to add various dopants during the deposition, and to deposit high quality thin films of different materials other than topological insulators, in both the MBE and PLD systems, we are excited to see the door to more interesting structures and fascinating physics opening in front of us.

Keywords: Applied Physics.
Advisor: Kapitulnik Aharon primary advisor. Thesis advisor
Beasley Malcolm advisor. Thesis advisor
Doniach S. advisor. Thesis advisor
Fast algorithms and imaging in strongly-scattering media [electronic resource]

In recent years, wave propagation in heterogeneous media has given rise to much academic interest. Indeed, both theory and experiments have demonstrated the vast array of physical phenomena, and the technical potential offered by such media. Examples include sub-wavelength imaging, filtering and beam shaping as well as cloaking. Computational results on the other hand are scarcer. The reason for this lies in the high computational cost associated with the solution of such problems. In the present dissertation, I developed an efficient algorithm allowing for the computational study and understanding of acoustic wave phenomena in highly heterogeneous media beyond the scope of current tools. This is done through the introduction of a new hybrid fast algorithm based on the Fast Multipole Method (FMM) and related ideas. I also use this new tool in order to investigate a phenomenon known as super-resolution, where energy is focused beyond the diffraction limit through time-reversal by adding small scatterers in the vicinity of a point source. I validated the concept through numerical experiments, and put forward some theoretical explanations based on the theory of homogenization for hyperbolic systems. In the final chapters of the dissertation, the reader will find a description of fast algorithms from a more general perspective through the introduction of a general black-box fast algorithm. The method is based on expansions of integral kernels through short exponential sums. Two schemes leading to such expansions are presented: one based on the Cauchy integral formula for analytic kernels, and the other based on a novel kind of quadrature called approximate Gaussian quadratures.

Advisor: Darve Eric primary advisor. Thesis advisor
Papanicolaou George primary advisor. Thesis advisor
Ryzhik Leonid advisor. Thesis advisor
Fast algorithms for dense numerical linear algebra and applications [electronic resource]

Large-dense matrices arise in numerous applications: Boundary integral equations for elliptic partial differential equations, covariance matrices in statistics, inverse problems, radial basis function interpolation, density functional theory, multi-frontal solvers for sparse linear systems, etc. As the problem size increases, large memory requirements — scaling as O(N^2) — and extensive computational time to perform matrix algebra— scaling as O(N^2) or O(N^3) — make computations impractical. The need for fast dense numerical linear algebra is hence of utmost significance. Most of the dense matrices arising out of applications can be efficiently represented by hierarchical matrices, which are data sparse representations of certain class of dense matrices. The thesis discusses innovative algorithms for hierarchical matrices and provides a novel paradigm for constructing fast direct solvers. The thesis also presents application of these algorithms to inverse problems and filtering in the context of seismic imaging.

Advisor: Darve Eric primary advisor. Thesis advisor
Kitanidis P. K. (Peter K.) advisor. Thesis advisor
Ying Lexing advisor. Thesis advisor
Fast and accurate PET image reconstruction on parallel architectures [electronic resource]

Positron Emission Tomography (PET) has become an invaluable modality for in vivo imaging of molecular signatures of disease. The reconstruction algorithm for PET and the resulting image quality, however, have been limited by the large scale nature of the inverse problem, prohibiting sophisticated statistical algorithms from being used in practice. This work addresses the challenges in PET image reconstruction using state-of-the-art techniques in parallel computing, computer graphics, image processing, and convex optimization. More specifically, we reformulate the image reconstruction algorithm so that it can run efficiently on the massively parallel architecture of the Graphics Processing Unit (GPU). Memory access patterns and execution controls are optimized to maximize device resource utilization. Furthermore, strategies for extending the parallel processing to a cluster of GPUs is developed, taking the inter-node communication overhead into consideration. Finally, the drastic reduction of the computational cost enables practical applications of three methods for image quality and accuracy improvement, including using Point Spread Function (PSF) for resolution modeling, utilizing Compton scattered events in the detectors, and combining multiple reconstructions to achieve higher Signal-to-Noise Ratio (SNR) in motion correction tasks. Experiments show that the proposed methods are able to improve image quality and accuracy while reducing execution time. Part of the work has been integrated into the next generation Philips Time-of-Flight (ToF) PET systems.

Keywords: Electrical Engineering.
Advisor: Levin Craig primary advisor. Thesis advisor
Nishimura Dwight George advisor. Thesis advisor
Xing Lei advisor. Thesis advisor
Fear and loathing in imperial Japan [electronic resource] : the cultures of Korean peril, 1919-1923

This dissertation explores the cultures of colonial terror in imperial Japan's metropole. Concomitant to attempts to discursively contain new resistance from colonized Korean subjects after World War I, narratives of conspiracy and terrorism featuring "treacherous Koreans" (futei Senjin) captivated Japan's imperial imagination through state discourse, tabloid journalism, pulp detective novels, travel writing, leftist literature, and popular rumor. This heralded an interwar era of "Korean Peril" in metropolitan print culture, rife with fictional and actual outbreaks of paranoia and violence. By examining the figuration of Korean Peril, this dissertation proposes that, although colonial vocabularies and narrative tropes worked to fix identities and manage the fear and violence attendant to imperial expansion, the process of popular narration frequently drew attention to the ironic gaps and ambivalent contradictions of Japan's approach to colonial empire. Chapter I documents the rise of Korean Peril in Japanese print as it mutated from an official construct of containment and differentiation into a stereotyped discourse of ethnic terror criminalizing all Korean subjects in sensational newspaper reporting. Chapter II considers how Korean Peril was progressively deformed in the process of exploiting the comingled terror and delight evoked by uncanny Korean figures within the unstable genre of Japanese tantei shōsetsu. These generic experiments ended with ambivalent and even unintentionally subversive twists. Chapters III and IV turn to critique and counter-narration of the discursive demonization of Korean rebels, in order to chart the new spaces that both Japanese and Korean writers used to debate and re-signify the terminology of colonial identity and resistance. In the realm of literary counter-discourse, anti-travelogues by the leftist writer Nakanishi Inosuke tread a fine line between complicity and subversion as they parodied both the colonizer's fear of the colonized and the genres of Korean Peril. Finally, Chapter V juxtaposes narratives and images that aimed to ironically reconstruct the 1923 post-earthquake "Korean Panic, " an explosion of communal violence that led to the murders of thousands of Korean residents of Japan, by treating the farcical trope of mistaken identity as a form of national self-critique.

Keywords: East Asian Languages and Cultures.
Advisor: Reichert Jim (James Robert) primary advisor. Thesis advisor
Carter Steven D. advisor. Thesis advisor
Levy Indra A. advisor. Thesis advisor
Federal R&D: Analyzing the Shift From Basic and Applied Research Toward Development

United States Federal Government research and development spending has shifted in recent years away from basic and applied research and toward development spending. Development is later in the product creation cycle and typically performed by private firms. A 2008 spike in development grants to private firms meant to combat the recession caused the increase, but the level going to private firms has only continued to rise after the recession ended and during the recovery. This paper examines potential explanations for this sudden and sustained increase. I present the economic theory regarding the positive externalities of research and development spending, and argue that basic research provides the largest spillover benefit externalities and is the most under selected in the private market equilibrium. Therefore, economic theory suggests that government focus a greater portion of its spending on basic research, and reverse the recent trend of increasing development grants to the private sector. Spillover benefits of development research have been largely internalized by patent policy that provides monopoly power to firms with innovative products, but intellectual property rights cannot internalize the larger and more powerful basic research externalities because basic research affects many markets. The private sector will never stop funding development research, so I argue that government should allocate more funds to the undervalued basic research fields to help correct the market failure.

Keywords:  Department of Economics
Stanford Department of Economics
United States
federal research and development spending
private firms
Thesis
Advisor: Taylor John
Federal Work-Study versus Off-Campus Jobs: Does the type of job matter for post-graduate outcomes?

The Federal Work-Study (FWS) Program was established as part of the Economic Opportunity Act of 1964 to help students find part-time employment to cover the cost of their tuition. Today, the U.S. government allocates nearly $1 billion in FWS funds for students in 3,000 institutions around the country. Even though the FWS program is large, it has not been studied comprehensively because of difficulties finding exogenous variation that explains endogenous work decisions. To overcome this issue, I exploit differences in FWS availability and FWS availability relative to other job opportunities at comparable institutions to instrument for FWS participation and hours worked in school. I find some evidence that FWS participation improves academic and post-graduation outcomes.

Keywords:  Department of Economics
Stanford Department of Economics
Work-study
employment
post-graduate outcomes
job quality
Thesis
Advisor: Hoxby Caroline
Fictions of destruction [electronic resource] : post-1945 narrative and disaster in the collective imaginary

In "Fictions of Destruction" I analyze post-1945 narratives that engage with the thematics and aesthetics of mass-scale destruction. The dissertation is based on the thesis that since the explosion of the atomic bombs, a shared imaginary of mass-scale disaster has developed that exhibits a set of concerns particular to the "Nuclear Age, " even while branching out into ecological, scientific and other possible sources of world-destruction. I first redefine the collective imaginary as a product of the oscillating, give-and-take relationship between cultural media and the individual's experience of the world, particularly with the advancement of mass communication technologies. I then give a comparative study of North American narrative fiction, particularly in the U.S., that hone in on issues related to the experience of temporality. These include the trope of the broken road as a move away from the rhetoric of progress and enlightenment and instead toward the impending downfall of modernity; the heightened awareness of risk and how it changes perceptions of futurity; what tropes of disaster fiction such as ephemera, wastelands, and bunkers reveal regarding historicity and possible futures; and how survivor character types illustrate the oscillation between hope and despair through their positions along the spectrum between stasis and action. In addition to its basis in comparative literary studies, this dissertation engages with a variety of disciplines in the humanities such as philosophy, cultural studies, film and media studies and history. Source materials include novels, short stories, graphic narratives, film, television and gaming.

Keywords: Comparative Literature.
Advisor: Gumbrecht Hans Ulrich primary advisor. Thesis advisor
Saldívar Ramón primary advisor. Thesis advisor
Eshel Amir advisor. Thesis advisor
Heise Ursula K. advisor. Thesis advisor