VictorJuiz/thesis huggingface dataset:
Biomechanics of human stratum corneum [electronic resource] : dry skin conditions, tissue damage and alleviation
Keywords: Materials Science and Engineering

The outermost layer of human skin, the stratum corneum (SC), is subject daily to variable ambient moisture and temperature conditions as well as application of potentially damaging cleansing agents. The inevitable results of these exposures are "tightness" of the skin which is directly related to the buildup of tensile residual drying stresses in the SC layer. In this work, we first describe the application of the substrate curvature technique to quantitatively measure the magnitude of these stresses and their relationship to selected drying environments and times. The SC drying stresses were observed to be very sensitive to the relative humidity and temperature of the drying environment as well as harshness of the chemical treatment. There was a strong correlation with the SC drying stresses and the chemical potential of water in the drying environment. The evolution of drying stresses in SC is discussed in relation to the effects of hydration and damage caused by chemical treatments on the underlying SC structure. We also describe the application of the substrate curvature technique to characterize stresses in occlusive topical coatings. We then extend the substrate curvature technique to measure the combined effects of the coating applied to human stratum corneum (SC) where the overall drying stresses may have contributions from the coating, the SC and the interaction of the coating with the SC. We show how these separate contributions in the coating and SC layers can be differentiated. Using this methodology, we characterize the effect of a range of moisturizing treatments on the drying stresses in human stratum corneum. Following moisturizer treatment, the SC was observed to have distinctive stress profiles with drying time depending on the effectiveness of the treatment. The stress values of specimens treated with the humectant moisturizers were observed to increase and stabilize after a few hours in the drying environment where they remained relatively constant until the end of exposure to the drying environment whereas the stress values of specimens treated with the emollient treatments were observed to rise rapidly to a peak stress value and relax to a final stress value. The effect of moisturizing treatments on the SC drying stresses was rationalized in terms of SC water loss and the chemical state of the SC components. Finally, we employ a fracture mechanics approach to understand the implications of the drying stresses in SC as a mechanical driving force for damage propagation (e.g. cracking and chapping) in the tissue. The crack driving force G was found for several cracking configurations and compared with the intercellular delamination energy, Gc, which is a property of the tissue that provides a measure of the resistance to cracking. Using this approach, we demonstrate how damaging treatments enhance and moisturizing treatments alleviate the propensity for dry skin damage.
Body Language Animation Synthesis from Prosody
Keywords: Computer Science.
Human-computer interaction
Computer animation
Firestone Medal for Excellence in Undergraduate Research
Ben Wegbreit Prize for Best Undergraduate Honors Thesis in Computer Science
Thesis

Human communication involves not only speech, but also a wide variety of gestures and body motions. Interactions in virtual environments often lack this multi-modal aspect of communication. This thesis presents a method for automatically synthesizing body language animations directly from the participants’ speech signals, without the need for additional input. The proposed system generates appropriate body language animations in real time from live speech by selecting segments from motion capture data of real people in conversation. The selection is driven by a hidden Markov model and uses prosody-based features extracted from speech. The training phase is fully automatic and does not require hand-labeling of input data, and the synthesis phase is efficient enough to run in real time on live microphone input. The results of a user study confirm that the proposed method is able to produce realistic and compelling body language.
Capital Structure as a Form of Signaling: The Use of Convertible Bonds
Keywords:  Department of Economics
Stanford Department of Economics
Thesis

In the face of asymmetrical information in financial markets, outside investors must rely on the firms’ actions in order to gain information known only to firm insiders. Such actions can be construed as signals of firm quality or internal projections of success, and capital structure can serve as one such signal. This study uses a sample of 100 convertible bonds issued from 1990 to 2007 to examine the market’s reactions to changes in the capital structures of the firms. A more debt-like issuance is theorized to result in positive abnormal returns, while a more equity-like issuance should result in negative abnormal returns. I also intend to investigate whether the use of capital structure as signaling differs with firms of different sizes, since information asymmetries would not be the same. This paper finds that the conversion premium of newly issued convertible bonds has a positive, statistically significant effect on the firms’ abnormal returns in the 30- and 200-day periods around the date of issuance. This effect is larger for smaller firms than for larger firms. However, the conversion premium has a much smaller, insignificant effect during the 10-day period, which may be caused by errors in determining the correct date that the market learned of the issuance
Carbon nanotubes [electronic resource] : device physics, RF circuits, surface science, and nanotechnology
Keywords: Electrical Engineering

In this dissertation, we report on our research to advance the understanding and development of carbon nanotubes into a functional nanotechnology that will enable novel applications and products. Our research approach is interdisciplinary in nature involving progress on many fronts including material synthesis, device physics and compact modeling, circuits, and monolithic integration with silicon substrates for optimum performance and integration. Specifically, this dissertation reports new results advancing the science and technology of carbon nanotubes including: i) analytical development of the physics of CNTs providing direct insight into the electro-physical properties, ii) experimentally-verified analytical current-voltage and capacitance-voltage characteristics of CNTs facilitating circuit design and analysis, iii) elucidation of the material science of nanotube synthesis enabling large-scale synthesis of aligned growth, and iv) monolithic integration of CNTs and CMOS for hybrid nanotechnology for future nanoelectronics.
Cell identity and wiring specificity in the Drosophila olfactory system [electronic resource]
Keywords: Biology.

The brain is a complex organ formed from billions of neurons. There are thousands of types of neurons, each with a unique morphology, function, gene expression profile and pattern of connectivity. This structure poses a very interesting developmental challenge: how do neurons acquire unique identities and connect to specific partner neurons during development? The Drosophila antennal lobe presents an attractive genetic model system in which to investigate these questions. In the antennal lobe, olfactory receptor neuron (ORN) axons project to glomeruli where they synapse with their partner projection neuron (PN) dendrites. These connections are highly stereotyped, as ORNs expressing the same odorant receptor converge on the same glomerulus and all PNs of the same class send their dendrites to the same glomerulus. Cell surface molecules are known to be crucial to instructing this specific wiring during development, and a transcriptional code likely dictates which cells express a particular cell surface molecule. However, the identities of many of these cell surface molecules and transcription factors remain unknown, and it is possible that additional cell types also inform the specific wiring of PNs and ORNs. In this thesis, I present work that furthers our understanding of the development and function of the fly olfactory circuit. First, I discuss a detailed characterization of local interneurons in the antennal lobe, dramatically expanding our basic knowledge of the types of cells present during development as well as central to information processing in the antennal lobe. Second, I present my work on the transcription factor longitudinals lacking (lola) that plays a role both in fate determination and wiring specificity of olfactory projection neurons, the second order cells that relay olfactory information to higher brain centers. Finally, I present an analysis of the regulatory elements driving expression of the projection neuron marker GH146 as a first step in defining transcriptional regulatory modules and identifying factors that may direct fate and wiring decisions in PNs.
Chemical inhibitor studies of polo-like kinase 1 in late mitosis and cytokinesis [electronic resource]
Keywords: Biochemistry

During cell division, chromosome segregation must be coordinated with cell cleavage so that cytokinesis occurs after chromosomes have been safely distributed to each spindle pole. Polo like kinase 1 (Plk1) is an essential kinase that regulates spindle assembly, mitotic entry and chromosome segregation but because of its many mitotic roles it has been difficult to specifically study its post-anaphase functions. Small molecule inhibitors were used to block Plk1 activity at anaphase onset and demonstrate that Plk1 controls both spindle elongation and cytokinesis. Plk1 inhibited cells failed to assemble a contractile ring and contract the cleavage furrow due to a defect in Rho and Rho-GEF localization to the division site. Plk1 inhibition did not affect anaphase A chromosome to pole movement but blocked anaphase B spindle elongation. Anaphase B is thought to result from the coordinated activities of microtubule-sliding motors that drive the poles further apart and changes in spindle microtubule dynamics. Plk1 is unlikely to control anaphase B through regulation of a spindle kinesin because inhibition of known motor proteins failed to recapitulate the Plk1 depletion phenotype. Instead, Plk1 inhibition caused a significant decrease in microtubule growth rate during metaphase and early anaphase, indicating a role for Plk1 in regulating microtubule dynamics. Consistent with an inhibition of microtubule growth rate, Plk1 inhibition reduced the rate of poleward microtubule flux in metaphase spindles and caused a reduction in metaphase spindle length that could be reversed by microtubule stabilization with taxol. These data suggest a model in which Plk1 accelerates microtubule growth during mitosis to maintain spindle length and drive anaphase B spindle elongation.
China's Foreign Exchange Reserves: Balancing Consumption with Investments in Treasury Bonds and Sovereign Funds
Keywords:  Department of Economics
Stanford Department of Economics
asset allocation
consumption
foreign exchange reserves
optimization
sovereign wealth funds
Thesis

Economists have long been curious about China’s conservatism with regard to managing its foreign exchange reserves, which exceeded the $2 trillion mark in early 2009. Usually, having more funds means that one can afford to take more risk, but China has managed its huge foreign exchange reserves cautiously, hoarding much of its reserves in relatively safe, but low-yield Treasury bonds, while investing only a small fraction into sovereign wealth funds, whose expected returns are more promising, but riskier. This has led many economists to conclude that China has managed its reserves sub-optimally. But by conducting simulations, I quantify the nature of China’s dual challenge of achieving decent investment returns while maintaining optimal consumption levels. These simulations are based on previous analyses of university endowments, which share some key similarities with China’s foreign exchange reserves. The results suggest that China may be vulnerable to short-term and long-term negative shocks to its foreign exchange reserves. In the end, I conclude that owing to its need to minimize risk, China’s conservative approach to managing its reserves, although counterintuitive to many economists, is fundamentally rational.
Default Options and Non-Standard 401(K) Choice
Keywords:  Department of Economics
Stanford Department of Economics
behavioral
retirement
anchor
status quo
choice-based
framing
Thesis

As policy makers search for ways to boost savings rates, automatic enrollment 401(k) plans are gaining popularity among employers in the United States. Such plans enroll new hires into default 401(k) funds at a default contribution rate with the option to opt out. The growing field of Behavioral Economics, meanwhile, has begun to incorporate framing effects such as default options into economic modeling. These effects have important implications for public policy. This paper presents a model of 401(k) choice that accounts for non-standard responses to default contribution rates. The parameters of this model are estimated using maximum likelihood estimation. To infer the policy implications of the model, this paper adopts a generalized normative framework that defines welfare in terms of choice. The observed data generate a parameterization that is consistent with the notion that defaults influence contribution rates through both anchoring bias and status quo bias. Moreover, welfare gains from automatic enrollment may not be as large as previously thought.
Developing Iraq’s Oil Industry to Maximize Government Net Revenues
Keywords:  Department of Economics
Stanford Department of Economics
Iraq
oil
Majnoon
international oil company
Iraq National Oil Company
Thesis

This paper seeks to determine whether (1) nationalizing Iraq’s oil industry or (2) developing it through production-sharing agreements with international oil companies (IOCs) will generate the highest amount of net revenues for the Iraqi government. I propose to use the development of the Majnoon oil field in southern Iraq as a case study to answer this question. I consider a timeframe of forty years and construct the estimated revenues and costs associated with developing Majnoon under nationalization, comparing them to those associated with developing Majnoon under a PSA similar to that employed in Oman. I conclude that if the Iraqis believe that the Iraq National Oil Company (INOC) can be at least 87.5% as efficient as an IOC, then Majnoon would be more profitable under nationalization. If the INOC cannot be at least 75% as efficient, then Majnoon would be more profitable under a PSA. If the INOC’s relative efficiency is between 75%-87.5% (deemed the “Indecision Interval”), then Iraqi decision-makers must engage in further analysis to determine the profit-maximizing option. The case of Majnoon provides insights important for the decision-makers to consider when deciding on whether to nationalize Iraq’s oil industry or not.
Economic adaptation of immigrants [electronic resource] : a comparative approach
Keywords: Sociology.

Previous studies on the effects of the context of reception on immigrant economic attainment have generally relied on information from detailed case studies. Focusing simultaneously on the characteristics of immigrant groups and the receiving society, these studies provided valuable information on the experiences of immigrants. However, they produced strikingly different accounts of the dimensions of the context that affect labor market attainment. Defining group membership by the country of birth and using multilevel modeling, I address this problem by constructing a comprehensive and systematic account of the factors affecting immigrant integration. I use data from the 2000 U.S. Census, the 2001 Canadian Census, and the New Immigrant Survey in constructing a model that explains a substantial portion of the variance in assimilation across groups. Specifically, it explains 79% of the group-level variance in earnings upon entry to the U.S. and 61% of the group-level variance in post-migration earnings growth. The model allows me to asses whether integration is shaped mainly by ethnic community resources or by external factors. Results show that ethnic community resources are more important in shaping patterns of incorporation than external conditions. The prominent ethnic community factors identified in this research are group socioeconomic advantage and ethnic concentration. However, I show that, among immigrants, the effects of ethnic community resources on earnings growth and the college wage premium are smaller in the Canadian context due to the combined effects of the differences between the countries in integration and immigration policy.I supplement these findings with a description of those groups with especially unfavorable prospects for earnings advancement, allowing me to contribute to the long-standing debate in immigration literature about the reasons for group differences in economic integration. Specifically, immigrants from certain Latin American and South East Asian countries remain economically vulnerable due to limited relative levels of both initial earnings and earnings growth. I explain the dismal integration prospects of immigrants from those groups by highlighting their disadvantages relative to immigrants from other groups in terms of socioeconomic group location and social distance.
Effective scheduling algorithms for service and computing systems [electronic resource]
Keywords: Electrical Engineering

A number of dynamic stochastic optimization problems of current interest are difficult to solve from both a practical as well as theoretical perspective. These problems are often said to suffer from the 'curse of dimensionality'. Unfortunately, there are few, if any, general methodologies to address these high dimensional optimization problems; such problems tend to be considered on a case-by-case basis. This is in stark contrast to deterministic optimization, wherein there exists techniques for large well-studied families of tractable problems such as convex optimization for continuous problems and submodular optimization over matroids for combinatorial problems. This thesis takes a first step towards constructing such a framework for high dimensional stochastic optimization problems. The main approaches focus on reducing the time horizon over which to optimize and/or making systematic modeling reductions. The scheduling problems presented in this thesis fall under a broad, general class of dynamic stochastic optimization problems whose objectives can be classified as either profit maximization, cost minimization, or a tradeoff between cost and delay minimization. This thesis presents effective, near optimal solutions to a number of hard scheduling problems which have received considerable attention in their own right including, but not limited to, parallel server queues, multimedia broadcast scheduling, product line design, the Adwords assignment problem, and hospital Intensive Care Unit Scheduling. The focus of this thesis is on evaluating the performance of myopic and myopic-like heuristics. This thesis presents a general framework in which to consider a number of dynamic optimization problems. Problems which can be cast in this framework will inherit the performance guarantees of the presented simple, yet effective, heuristic policies.
Essays on consumer credit markets [electronic resource]
Keywords: Economics.

This dissertation studies the organization of consumer credit markets using a rich and novel dataset from a large subprime auto lender. Its primary goal is to develop empirical methods for analyzing markets with asymmetric information and to use these methods to better understand the behavior of subprime borrowers and lenders. The first chapter quantifies the importance of adverse selection and moral hazard in the subprime auto loan market and shows how different loan contract terms serve to mitigate these distinct information problems. The second chapter examines the impact of centralized credit scoring on lending outcomes, including the distribution of performance across dealerships within the firm. The third chapter studies borrower repayment behavior and quantifies the impact of ex post moral hazard on interest rates and the costs of default. Collectively, the three chapters provide a better understanding of the functioning of markets for subprime credit in the U.S. They also provide unique empirical evidence on the importance of asymmetric information and the value of screening, monitoring, and contract design in consumer credit markets in general.
Fast photoconductive materials for wideband A/D conversion and monolithic integration with CMOS [electronic resource]
Keywords: Materials Science and Engineering

All-electronic analog-to-digital converter (ADC) performance is limited by low input bandwidth and high aperture uncertainty. To benefit from the bandwidth and timing accuracy advantages of photonic devices, we investigated a photoconductive-sampling-based photonic A/D conversion system utilizing low-temperature-grown GaAs (LT-GaAs) metal-semiconductor-metal (MSM) photoconductive switches which were flip-chip-bonded with silicon-CMOS ADCs and demonstrated a two-channel prototype system with ~ 3.5 effective-number-of-bits of resolution over an input bandwidth up to 40 GHz and an estimated sampling jitter of less than 80 fs. We studied three material systems targeting the high-speed photoconductive switch application. First, for LT-GaAs films grown on GaAs substrates, we significantly improved the MSM switch performance by systematic optimization of LT-film growth and annealing conditions according to design-of-experiments (DOE) principles. The full-width at half-maximum switching window characterized by electro-optic sampling is ~ 2 ps. To enable monolithic integration of GaAs devices with finished Si IC chips, we studied low temperature growth of GaAs films, both on Si substrates and on SiO2 films. All the experiments, including film growth, annealing and device processing, were performed at temperatures safe for completed IC chips with final metallization and passivation layers. Testing results showed that the switch performance was comparable to or exceeded the reference LT-GaAs switches made on GaAs wafers which were used to fabricate the prototype ADC system. As a final proof of concept, we successfully integrated polycrystalline GaAs switches monolithically on a completely fabricated CMOS amplifier and achieved a functional optical receiver without modifying the underlying Si circuit performance. The beauty of this approach is its simplicity, minimum fabrication disturbance and greater applicability into other areas. We believe this to be the first successful demonstration of monolithic integration of GaAs devices on a fully completed Si chip, and most importantly, demonstrating fully functional and un-degraded performance.