VictorJuiz/thesis huggingface dataset:
Faster fidelity for better design [electronic resource] : a scalable model order reduction framework for steady aerodynamic design applications

This thesis proposes a framework for building and leveraging Reduced Order Models (ROMs) for industrial-scale steady-state nonlinear Computational Fluid Dynamics (CFD) applications involving shape parameters. This framework is enabled by four distinct contributions. First, a local ROM framework is matured for steady applications, with an emphasis on consistent affine approximations. Second, a suitable approach for handling parametric geometry is proposed, utilizing volumetric deformation techniques to morph a body-fitted mesh. Third, a robust solution strategy is proposed for predictive steady-state CFD applications. Finally, the full framework is implemented in a high-performance computing environment, and can scale to large applications. The numerical experiments in this work represent the first demonstrations of predictive ROMs for realistic nonlinear CFD applications. In these experiments, the proposed ROM framework is shown to predict integrated forces with accuracy similar to simple data-fit approaches, and is shown to predict distributed quantities with better accuracy than simple data-fit approaches.

Keywords: Aeronautics and Astronautics.
Advisor: Farhat Charbel primary advisor. Thesis advisor
Alonso Juan José
Jameson Antony
Fear Conditioning in Siberian Hamsters: Circadian Effects and Sex Differences

Circadian modulation of contextual and cued fear conditioning (FC) has been investigated in mice, but not in the Siberian hamster, Phodopus sungorus. This study tested whether measuring locomotor activity suppression, a validated index of fear in rodents, during FC reveals a circadian rhythm to FC performance, both in hippocampal and non-hippocampal dependent memory tasks. Animals were exposed to a series of tones followed by footshocks during the first two days of training, then tested for their cued recollection of the tone in a novel environment two days later. Locomotion and activity state were continuously measured via video during testing. Our data suggest that both contextual and cued memory ability are stronger during the light phase than the dark, as indicated by a greater increase in inactivity measurements during the light. Therefore, there exists a significant circadian rhythm in P. sungorus contextual and cued FC, although the latter’s rhythm only manifests itself after several exposures to the tone. On the whole, there were few appreciable sex differences, with the exception of the Inactive Events and Bouts measurements for contextual FC. These results verify the robustness of FC and the inactivity measurement as an evaluation of learning and memory in P. sungorus.

Keywords:  Department of Biology
Biology
circadian
rhythm
fear
conditioning
hippocampus
amygdala
learning
memory
neurobiology
locomotor
activity
tone
Siberian
hamster
Phodopus
sungorus
Thesis
Advisor: Heller Craig
Fernald Russell
Financial crises, firms' innovation and the macroeconomy [electronic resource]

This dissertation analyzes the interaction between financial crises and firms' innovation, its macroeconomic consequences and the implications for economic policy. The first chapter, "The Financing of Ideas and the Great Deviation", studies the macroeconomic impact of financial shocks through their negative effect on intangible capital investment, using a panel dataset of Spanish manufacturing firms. The second chapter, "How Destructive is Innovation?", is co-authored with Chang-Tai Hsieh and Peter J. Klenow. It quantifies the contribution of different innovation channels to aggregate economic growth, matching a growth model to statistical moments on establishment dynamics in the U.S. The final chapter, "Macroprudential Policy with Liquidity Panics", is co-authored with Alonso Villacorta. It shows how financial panics can appear endogenously due to precautionary cash accumulation by firms, and how this changes the optimal macroprudential policy.

Keywords: Economics.
Advisor: Klenow Peter J. primary advisor. Thesis advisor
Schneider Martin (Professor of economics) primary advisor. Thesis advisor
Bloom Nick
Piazzesi Monika advisor. Thesis advisor
Financial reporting quality and voluntary disclosure [electronic resource]

This thesis is comprised of two essays that explore how investors' uncertainty over financial reporting quality influences firms' voluntary disclosures. I consider two shocks that cause investors to assign a higher likelihood of restatement and examine how managers respond using voluntary disclosures. Managers inform stakeholders of the firm through mandatory disclosures (e.g. financial statements) and voluntary disclosures (e.g. earnings forecasts, conference calls, press releases). Financial reporting quality represents the extent to which financial statements faithfully reflect the underlying economics of the firm, and therefore, how much stakeholders can learn from these mandatory disclosures alone. The focus of this thesis is on how managers use voluntary channels to inform stakeholders following shocks to investors' expectations of financial reporting quality.

Keywords: Business.
Advisor: McNichols Maureen
Marinovic Iván advisor. Thesis advisor
Piotroski Joseph D. (Joseph David) advisor. Thesis advisor
Finding needles in a haystack [electronic resource] : molecular similarity and machine learning for drug discovery applications

We are in the midst of a machine learning revolution. From self-driving cars to clinical diagnostics, machine learning promises to change the way we live our lives and make decisions. Applied to drug discovery, machine learning enables us to build upon existing experimental data and more effectively explore the vastness of chemical space for new therapeutics. In particular, virtual screening allows us to evaluate many more compounds and biological targets than we can test experimentally, helping to identify starting points for further development. In this dissertation, I present several applications of machine learning to drug discovery. Much of the work presented here focuses on multitask neural networks---variants of the models that have transformed computer vision and beaten some of the world's best Go players. Applications of these models to ligand-based virtual screening demonstrate improvements over standard machine learning methods such as random forest and logistic regression. I also describe neural network models built on simple encodings of the molecular graph, moving beyond traditional fingerprint-based screening methods to a richer and more flexible input representation.

Keywords: Structural Biology.
Advisor: Pande Vijay primary advisor. Thesis advisor
Altman Russ advisor. Thesis advisor
Das Rhiju
Fine-grained recognition [electronic resource] : data, recognition, and application

Fine-grained recognition refers to the task in computer vision of automatically differentiating similar object categories from one another, e.g. species of birds, types of cars, breeds of dogs, or varieties of aircraft. Applications are numerous: beyond simply being able to describe the world in more detail, fine-grained recognition can be used for improved scene understanding, studying society, and even analyzing biodiversity. Unfortunately, fine-grained recognition is extremely challenging. Even acquiring data is difficult due to the expertise required in annotation, and differences between categories can still be extremely subtle and formidable to learn. In this work, I will describe the efforts I have made toward tackling fine-grained recognition. These include four projects aimed at improving automatic recognition of fine-grained categories, which look at both the data and recognition algorithms used. I also describe an application of fine-grained recognition in understanding society from images. Finally, I present a work looking at finer-grained natural language descriptions of images.

Advisor: Li Fei Fei
Ermon Stefano advisor. Thesis advisor
Savarese Silvio advisor. Thesis advisor
Firm strategy in early-stage ecosystems [electronic resource]

Many industries consist of networks of interdependent firms that offer discrete products or services that together comprise a valuable solution. Within these networks, often termed ecosystems, firms depend on one another to create value, but simultaneously compete with one another to capture value. Prior research on ecosystems has generally examined firm strategy in established ecosystems, in which the identity and relationships between firms and components are known. Less is known about firm strategy in early-stage ecosystems, which are those that are in an early state of emergence or evolution. This dissertation addresses this gap through three linked studies. The first is an inductive multiple-case study of five firms in the nascent US residential solar ecosystem as it emerged from 2007 to 2014. The second is a formal mathematical model that examines how the level of competition (ecosystem vs. component) affects firms' ability to create and capture value in nascent ecosystems. The third moves from nascent to evolving ecosystems, and presents a cooperative game theory model that examines how and when firms can collaboratively resolve technological constraints that inhibit their ability to jointly create and capture value. Together, the studies in this dissertation offer rich theory regarding how firms can succeed in early-stage ecosystems, despite the uncertainty and ambiguity that characterizes these settings. Overall, this research contributes to the literatures on strategy, organizations theory, and entrepreneurship.

Keywords: Management Science and Engineering.
Advisor: Eisenhardt Kathleen M. primary advisor. Thesis advisor
Eesley Charles advisor. Thesis advisor
Katila Riitta advisor. Thesis advisor
Flat optics based on dielectric gradient metasurfaces [electronic resource]

Metasurfaces provide unprecedented control over light propagation by imparting local, space-variant phase changes on incident electromagnetic waves. They have contributed to the replacement of bulky optical components with ultrathin planar elements. They can also improve the performance of conventional optical elements and facilitate the creation of optical components with new functionalities. We first describe the operating principles and the experimental demonstration of dielectric gradient metasurface optical elements (DGMOEs) that capitalize on the development of high-index dielectric optical antenna and Pancharatnam-Berry phase optical elements. In particular, we illustrate how ultrathin gratings, lenses, and axicons, operating in transmission mode in the visible spectrum, can be realized by patterning a 100-nm-thin Si layer into a dense arrangement of judiciously arranged nanostructures. Additionally, we build on the knowledge obtained from the development of shared-aperture phased array antennas and Si-based gradient metasurfaces to fabricate various multifunctional metasurfaces capable of achieving multiple distinct functions within a single surface. In particular, we demonstrate that interleaving of multiple optical elements can be accomplished without reducing the aperture of each sub-element. Multifunctional optical elements constructed from a Si-based gradient metasurface are realized, including polarization-independent metasurfaces and axial and color separating metasurface lenses. We also demonstrate multi-wavelength color imaging with high spatial resolution using an axial multifunctional metasurface. Finally, an optical imaging functionality with simultaneous color separation is obtained using a color separating metasurface. Lastly, we develop a multiplexed metasurface lens array based on multi-functional dielectric gradient metasurfaces to replace the conventional microlens array in light-field imaging applications. The multiplexed metasurface lens arrays allow simultaneous 3D imaging at a high spatial resolution, which overcomes the trade-off between spatial and angular resolutions when using a conventional microlens array constructed from a series of lenslets with a small aperture size. These Si-based gradient metasurfaces offer facile integration with electronics and can be manufactured using mature semiconductor fabrication techniques. They open up a myriad of opportunities in the fields of optical communications, advanced computational imaging and display systems.

Keywords: Electrical Engineering.
Advisor: Brongersma Mark L. primary advisor. Thesis advisor
Fan Shanhui
Miller D. A. B. advisor. Thesis advisor
The formation and evolution of a neural code for rewarding memories [electronic resource]

Memories of rewarding episodes can be vivid and contain detail that lasts a lifetime. The mammalian hippocampus is essential for the formation of episodic memory, but how it supports the privileged encoding and long-term retention of memories for rewarding events is poorly understood. Hippocampal CA1 pyramidal cells exhibit place fields at a higher prevalence around reward locations, however, it has been unknown how CA1 representations of rewarding experiences form and evolve over the timescales of long-term memory formation. We used a head-mounted miniature fluorescence microscope to track the calcium dynamics of > 10,000 CA1 pyramidal cells expressing the calcium indicator GCaMP6m as freely behaving mice learned to perform a reward-motivated spatial task over 9 consecutive days. The CA1 ensemble showed progressive refinement as the mice learned the association between place and reward. We observed the formation of a place field over-representation of the rewarded location, the magnitude of which increased with learning. Selective recruitment, remapping and stabilization of cells at the reward location supported the formation and maintenance of this over-representation. Ensemble decoding of the mouse's position from the population of imaged neural activity suggested that both the preponderance of place fields and narrower field widths contributed to better representational accuracy of the reward location. These results suggest that long-term refinements to the over-representation of rewarded locations may support reward-associated spatial memory.

Keywords: Applied Physics.
Advisor: Schnitzer Mark Jacob
Ganguli Surya
Wagner Anthony David advisor. Thesis advisor
Forms of poetic attention [electronic resource]

The notion of "poetic form" is as old and familiar as the study of poetry itself, an unquestioned shorthand for "how poems work." But what exactly is formed in a poem? At its core, I argue, poetry is an event of attention generated in the acts of reading and writing. This dissertation offers a systematic exploration of this premise, analyzing how poems compose attention and how attention in turn constitutes poetry's primary material. In doing so, the project also theorizes the process of attention-making itself: its objects, coordinates, and variables. I focus primarily on the American twentieth century, augmenting this modern focus with examples drawn from earlier and nonwestern poets, such as Sappho, Al-Khansa', and William Shakespeare. Making explicit the centrality of attention to poetic experience, this dissertation develops a method and terminology for identifying the dynamics of poetic attention and distinguishes this specifically poetic attention from other varieties of attention. Part One focuses on the dynamics of "transitive" attention, or modes of attention that take an object. Drawing on attention studies in phenomenology, psychology, and cognitive science, I identify five essential dynamic coordinates of transitive attention: intentionality, interest, selectivity, spatiotemporal remove, and apprehension. I demonstrate this process through an exploration of four primary categories of transitive attention: desire (reading Shakespeare, Emily Dickinson, and Robert Hass), contemplation (George Oppen, Wallace Stevens, and Rolf Dieter Brinkmann), recollection (Geoffrey Hill, Anne Carson, and Theresa Hak Kyung Cha), and imagination (William Wordsworth, Rainer Maria Rilke, and John Burnside). In each case, I constellate several close readings to unfold the complexity of each mode. In Part Two, I turn to the dynamics of "intransitive" attention, exploring how poetic attention functions when, aside from the formal object that is the poem itself, there is no central object of focus. As in Part One, I begin by parsing the dynamic coordinates of intransitive attention, which include intentionality, the presence or absence of an indirect object, scope, temporal inflection, and subjectivity. I then identify and explore four applied modes: vigilance (reading Stéphane Mallarmé and Friedrich Hölderlin), resignation (Arthur Rimbaud and Charles Wright), idleness (Joan Retallack, Frank O'Hara, and A.R. Ammons), and boredom (Charles Bukowski, Thom Gunn, and T.S. Eliot). This research makes explicit what has been an unspoken intuition among poets and critics alike for centuries: that poetry is at its core an event of attention, that it forms and is formed by attention, that this poetic attention is of human value, and that it might be cultivated—sharpened, sensitized, quickened, refined—through the practice of reading and writing poetry.

Keywords: Comparative Literature.
Advisor: Greene Roland
Gumbrecht Hans Ulrich primary advisor. Thesis advisor
Eshel Amir advisor. Thesis advisor
Landy Joshua
For-profit vs. nonprofit [electronic resource] : strategies of competition and collaboration in the continuing care industry

Few changes in the organization of healthcare in the United States have stimulated more interest and alarm than the rise of a new form of entrepreneurism -- Investor-owned, for-profit organizations that provide health services as a business. Although ours is a predominantly capitalistic society, there have long been concerns about the possible adverse or pernicious effects of profit motivations in healthcare. The majority of the previous empirical studies comparing performance between for-profit and nonprofit healthcare providers suggested that nonprofit providers were superior. However, few studies focus specifically on the continuing care providers. In this dissertation, I first examine the impact of ownership status ─ for-profit vs. nonprofit ─ on occupancy rate, price, and quality of service in the continuing care industry through an empirical study in California. In this empirical study, I collect data from the California Department of Social Services (CDSS) and on-site interviews in 26 Continuing Care Retirement Communities (CCRCs) in California. In the second part of this dissertation, I set up a two-sided market framework to model the competition between for-profit and nonprofit CCRCs. CCRCs serve as platforms that link together residents on one side and service providers on the other side. By highlighting this two-sided market structure, my model provides new insights to understand the increase in for-profit CCRC's market shares observed in the last decade in the US. Also, the modeling results can help the management in for-profit and nonprofit CCRCs better understand their different strategic positions and assist in their decision-making for market competition and collaboration. In the final chapter of the dissertation, I investigate how these lessons learned from the senior care industry in the U.S. can be adapted to the different cultural and social backgrounds in developing countries such as China, which is emerging as an aging society and has recently started planning and building its senior care infrastructure.

Keywords: Management Science and Engineering.
Advisor: Tse Edison primary advisor. Thesis advisor
Katila Riitta advisor. Thesis advisor
Weyant John P. (John Peter) advisor. Thesis advisor
Fragmentation of media tasks on a laptop computer [electronic resource] : moment-by-moment analysis of task-switching and writing performance

Traditional media activities -- watching a movie, listening to a song, reading a news story, writing an essay -- have typically included a one-to-one mapping of media activity and media device. Modern digital technologies, however, have altered the context in which the majority of media content is experienced: today much of our mediated lives are spent on one or two devices -- laptops, tablets, smart phones -- that centralize and permit rapid switching between a wide variety of content. Activities that were once completed -- and studied -- in isolation are now fragmented and re-woven in a form of media multitasking that takes place on a single screen, engaged in a context very different from traditional modes and likely to influence processing of message content and performance on mediated tasks. The present field study includes a two-stage approach to better understanding the process, not just the outcomes, of completing media tasks in the modern context of interwoven experiences of different content. The first stage is an exploration of this behavior while working on writing tasks, through direct monitoring of media use over an extended period in natural settings. The second stage sought to evaluate how writing task performance is impacted by the fragmentation inherent to laptop computer use, testing hypotheses about task performance derived from the psychological literature on cognitive task-switching. Results revealed that writing tasks are completed in short bursts of time (median = 51 seconds) and small blocks of composition (median = 10 words added or removed in a single burst), with writing sessions consisting of jumbled sequences of time spent writing, time spent on content relevant to the task at hand, and time spent on wholly unrelated media stimuli. The impact of this process on writing performance is moderated by several structural and content-related parameters (e.g., duration of writing segments, time away from the document, frequency of switches, relatedness of content accessed prior to a writing segment, and interactions between these factors), and dependent upon the metric of performance considered (e.g., readability of writing, words added, active editing while writing, deletion of previously written text). Implications for writing strategy and instruction, as well as the need for modern effects researchers to observe media use in its full, fragmented context, are discussed.

Keywords: Communication.
Advisor: Reeves Byron
Bailenson Jeremy advisor. Thesis advisor
Hamilton James
Schwartz Dan
Framing Marlow: The Limits of Glamour and Obscurity in Joseph Conrad's Adventure Novellas

This thesis examines Joseph Conrad's modernist subversion of the typical nineteenth century adventure narrative, focusing on Conrad's criticism of the obscurity and glamour of adventure. The thesis brings in insights from modern sociological and political framework theories to examine the frame narrative structures of two of Conrad's novellas: Youth (1898) and Heart of Darkness (1899). The thesis propels against arguments of multiple Conrad critics by sourcing Conrad's modernism to the frame narrative structures of his novellas, rather than his use of obscure language.

Keywords:  Department of English
Joseph Conrad
Conrad
modernism
adventure
obscurity
glamour
frame
frame narrative
English
Stanford University
Stanford
Thesis
Advisor: Jarvis Claire
McGurl Mark