VictorJuiz/thesis huggingface dataset:
Visual cortical circuitry for building word representations [electronic resource]

Reading is the remarkable human ability to decode the sounds and meaning of language from an intricate combination of strokes of ink. This perceptual capacity is tolerant to changes in size, font, and other visual features of text. Transformations of the neural representation between many neural modules, including primary visual cortex (V1), other retinotopically organized areas, and language regions, are necessary for successful reading. An important focus of previous work has been on characterizing word representations in ventral occipito-temporal cortex, in particular in a left-hemisphere region known as the visual word form area (VWFA). To better understand the transformations occurring between V1 and the VWFA, we measured (using functional magnetic resonance imaging, fMRI) and perturbed (using transcranial magnetic stimulation) neural responses in several visual areas while subjects read words defined by atypical visual features (Chapter 2). We show that VWFA responses are invariant to the visual features that define word stimuli, and we show how flexible neural circuitry accounts for these abstract representations. While these studies contribute to understanding the VWFA's inputs, the inner organization of the VWFA remains unexplored. We describe experiments that use fMRI and electrocorticography (ECoG) in the human brain to show that the VWFA is sensitive to visual field position, and that together with a homologous right-hemisphere region, its inner organization encompasses a retinotopic map (Chapter 3). Information about abstract word forms is in turn transferred from the VWFA to language areas of the brain. This transfer occurs via large white-matter bundles that can be measured with diffusion imaging (DTI). We compare data from a severely dyslexic individual to a group of control subjects and show that the individual's deficits are due to a missing arcuate fasciculus, one of the major pathways important for reading and language (Chapter 4). This set of experiments ties together several fields of neuroscientific inquiry, including early visual processing, complex visual object representations, and language. Ultimately, if we are to understand how spots of light are transformed into sounds and meaning, we must unravel the smaller transformations that occur within all these components of the reading circuitry.

Keywords: Neurosciences.
Advisor: Wandell Brian A. primary advisor. Thesis advisor
Newsome William T. advisor. Thesis advisor
Parvizi Josef advisor. Thesis advisor
Wagner Anthony David advisor. Thesis advisor
Volcanic Stratigraphy of Massacre Rim, Northwest Nevada: Changing Mantle Sources of Mid- to-Late-Tertiary Basalts

At Massacre Rim in Washoe County, NV, exposures of volcanic strata dating from the Oligocene through the Pliocene are present. This stratigraphic succession includes at the lowest exposed level the rhyolitic 26-ma Fortynine Mountain ignimbrite and mafic lavas and associated phreatomagmatic deposits. These Oligocene units are overlain by the 16-ma Summit Lake Tuff and an alkali olivine basalt of presumed mid-Miocene age. Overlying all of them are low-K olivine tholeiitic lavas that have been dated regionally to ~10-0.5 Ma. Though thin, the low-K olivine tholeiite lavas cover an extensive area, blanketing the landscape in northwestern Nevada with flat to shallowly dipping sheets that form broad tablelands.

Keywords:  Department of Geological and Environmental Sciences
School of Earth Energy &amp; Environmental Sciences
stratigraphic groups
Nevada
Thesis
Advisor: Mahood Gail A.
Egger Anne E.
Voting with Bidirectional Elimination

Two important criteria for judging the quality of a voting algorithm are strategy-proofness and Condorcet efficiency. While, according to the Gibbard-Satterthwaite theorem, we can expect no voting mechanism to be fully strategy proof, many Condorcet methods are quite susceptible to compromising, burying, and bullet voting. In this paper I propose a new algorithm which I call “Bidirectional Elimination,” a composite of Instant Runoff Voting and the Coombs Method, which offers the benefit of greater resistance to tactical voting while nearly always electing the Condorcet winner when one exists. A program was used to test IRV, the Coombs Method, and Bidirectional Elimination on tens of billions of social preferences profiles in combinations of up to ten voters and ten candidates. I offer mathematical proofs that this new algorithm meets the Condorcet criterion for up to 4 voters and N candidates, or M voters and up to 3 candidates; beyond this, results from the program show that Bidirectional Elimination offers a significant advantage over both IRV and Coombs in approaching Condorcet efficiency.

Keywords:  Department of Economics
Stanford Department of Economics
Voting
tactical voting
Condorcet criterion
instant runoff voting
Coombs Method
Thesis
Advisor: Levin Jonathan
Water access, hand hygiene, and child health in sub-Saharan Africa [electronic resource]

Diarrhea is a leading cause of under-five child mortality in sub-Saharan Africa, where one in eight children dies before reaching the age of five. Only 31% of the sub-Saharan Africa population has access to improved sanitation facilities, and 60% have access to improved water supply. This dissertation attempts to better understand how water access and hand hygiene affect diarrheal disease transmission in sub-Saharan Africa, with a particular focus on households with young children using non-networked water supplies. First, the relationship between household access to water and child health is quantified using data on over 100,000 households from 26 countries in sub-Saharan Africa. Having to walk further to fetch water is found to be associated with child diarrhea, low height and weight, and under-five mortality. Next, field studies from Tanzania provide evidence of the role that hand hygiene plays in transmission of fecal contamination and illness. High levels of fecal bacteria on mothers' and children's hands are found to be correlated to household water quality and child illness. Third, an observational study identifies particular household activities that cause increased hand contamination. A final investigation explores the potential for waterless hand sanitizer to improve hand hygiene in highly contaminated environments with limited access to water supply.

Advisor: Boehm Alexandria primary advisor. Thesis advisor
Davis Jenna (Professor)
Miller Norman
Welfare fraud, citizenship, and resistance [electronic resource] : Israeli women's attitudes towards workfare ideology

This article exposes the political dimensions of welfare fraud by investigating--in the context of the Israeli post welfare reform of 2003--how 49 Israeli women who live on welfare justify welfare fraud. I find that women's justifications cannot be fully explained by traditional non-compliance theories that view welfare fraud as an individual, private, criminal activity that solely reflects on the fraudster's moral character or desperate need. Instead, women's justifications for welfare fraud are better understood as a socio-political struggle for inclusion and deservedness--as a clash between poor women's and the state's competing conceptions of citizenship along the lines of women's unpaid care work. My main finding points to the fact that women differentiate welfare fraud from other forms of illegal acts, which they condemn, based on their sense that they are morally entitled to receive state support. Hence, it reveals that women's justifications for welfare fraud contain a collective political claim. In addition to a collective ideology, the women's fraudulent acts are also maintained through a "culture of resistance". Hence, I show that unlike the traditional view of welfare fraud, women's fraudulent behavior bears social and political meaning and significance. Nevertheless, I also demonstrate that such form of resistance is inevitably limited in its ability to promote structural change due to the power dynamics it is embedded in.

Keywords: Law.
Advisor: Hensler Deborah R.
England Paula advisor. Thesis advisor
Marshall Lawrence C.
Rhode Deborah L. advisor. Thesis advisor
When does gender matter? Gender segregation in the professions of medicine, teaching and law [electronic resource]

In this dissertation, I investigate when and why gender segregation occurs in the professions of medicine, law and teaching. Drawing on social psychological perspectives on gender and theories on career development, I posit that segregation patterns differ across these three occupational contexts due to differences in gender valence of jobs and structures of career process. Specifically, I argue that early career choices are more gender-segregated in the highly gendered context of medicine and teaching, while the extent of gender segregation may vary (and increase) more substantially over time in the less structured contexts of teaching and law. Using data from professional organizations and government sources, I analyzed careers of a cohort of doctors, lawyers and teachers from their entry into their professions in 1991-1994 to 10-17 years after entry. Consistent with my hypotheses, doctors and teachers displayed highly gender-different aspirations than lawyers, and whereas the level of gender segregation remained fairly constant for doctors, it fluctuated somewhat for teachers and increased substantially for lawyers, particularly after the first six years of work. Analysis of 39 in-depth interviews further suggests that job choices among doctors and teachers reflect deeply held gendered ideas about people and work, whereas job choices among lawyers are seen as series of adjustments to organizational contexts, adjustments that usually differ for women and men. In total, these findings make the case for a more detailed view of intra-occupational gender segregation, one that places gender processes within the occupational context. In proposing a context-driven paradigm for studying gender inequality, this study brings the occupation to the center of the investigation, and argues for a more expansive view of gender segregation that takes into account the meanings and structures that delineate career decision-making and the constraints on the process.

Keywords: Sociology.
Advisor: Grusky David B. primary advisor. Thesis advisor
Ridgeway Cecilia L. advisor. Thesis advisor
Snipp C. Matthew advisor. Thesis advisor
Why are Some Diversified U.S. Equity Funds Less Diversified Than Others? A Study on the Industry Concentration of Mutual Funds

Some diversified U.S. equity fund managers hold investments concentrated in one or a few specific industries. This paper investigates why some fund managers hold more concentrated portfolios. Using data on actively managed U.S. mutual funds from 2003 to 2010, I find that managers of more concentrated funds have their skills vary more across different industry sectors. Consequently, they earn a premium by overweighing their portfolios in industries they have comparative advantages in after controlling for risk and style differences using various benchmarks. My results also suggest that managers of more concentrated funds are more skilled, but also on average less responsive to macroeconomic opportunities. Finally, I find a manager’s choice of industry concentration is also influenced by her investment style and the size of her fund.

Keywords:  Department of Economics
Stanford Department of Economics
United States
equity fund managers
fund concentration
Thesis
Advisor: Harding Matthew C.
Wyner-Ziv coding of video [electronic resource]

For numerous video compression scenarios, encoding is performed on low-power or mobile devices. Examples of such systems include wireless video sensors for surveillance, wireless PC cameras and mobile phones. For these applications, encoding must be implemented at the camera where memory and computation are scarce and low power usage is essential. Current video compression standards, such as MPEG or H.264/AVC, exploit the redundancy among video frames at the encoder. Due to the interframe processing performed at the encoder, these compression schemes are less suitable for applications which require low-complexity encoders. The Slepian-Wolf theorem on distributed source coding and the Wyner-Ziv results on source coding with decoder side information suggest that we can achieve efficient compression by exploiting the source statistics only at the decoder. Motivated by these theoretical results, a Wyner-Ziv video codec is developed. In this compression scheme individual frames are encoded independently, but decoded conditionally on adjacent reconstructed frames. Independently encoding the frames leads to low computation and memory requirements at the encoder, while the interframe processing at the decoder allows for efficient compression. As a building block for the Wyner-Ziv video codec, a practical scheme for compression with decoder side information based on turbo codes is presented. This coding technique performs close to the Slepian-Wolf bound and allows for rate-adaptivity and joint source-channel decoding. The Wyner-Ziv video codec is implemented in the pixel domain and the transform domain. Simulation results show that this video compression scheme achieves better rate-distortion performance than conventional low-complexity encoding schemes. To further improve the performance of the Wyner-Ziv video codec, two extensions are presented. Specifically, we implement hash-based motion estimation at the receiver. This allows the system to effectively estimate the motion at the decoder. We also extend the system to Wyner-Ziv coding of the residual images of a video sequence. With this scheme, the encoder uses a simple reference frame to calculate the residual while the decoder performs more sophisticated motion-compensation to generate side information for conditional decoding.

Keywords: Electrical Engineering
Advisor: Girod Bernd primary advisor. Thesis advisor
Goldsmith Andrea
Weissman Tsachy advisor. Thesis advisor
X-ray spectroscopy and scattering study on aqueous solutions of small organic molecules [electronic resource]

Water interacts with molecules through many different ways. Polarity of the solute molecule plays a very important role in inter-molecular interactions in aqueous solutions of organic molecules. Techniques of X-ray spectroscopy and scattering have been developed since last decade to investigate the hydrogen bond (H-bond) structures in liquid water and solutions. This thesis summarizes the results of studies by those techniques on interactions between water and apolar (hydrophobic effects) or polar groups (dipole interaction and H-bond ) of small organic molecules. Size dependence of hydrophobic effects were studied in amphiphilic (CnH2n+1)4NBr solutions as the size of cations grows with n increasing from 1 to 4. Oxygen K-edge X-ray absorption measuring the H-bond structure of water in 1 molality amphiphilic solutions shows crossover of hydrophobic hydration by relating the change in the Hbond structure to a corresponding temperature change and small angle x-ray scattering demonstrates the crossover of hydrophobic interaction by associating diffraction peaks to cation contact pairs. The difference in the temperature effects on interaction between cations further strengthens the hypothesis of the crossover of hydrophobic effects in the solution by XAS and SAXS at room temperature. The aqueous solution of MeCN is explored to demonstrate how water interacts with polar solutes. Both hydrogen bond and dipole interaction between the two species are present in the solution resulting micro-heterogenity or density fluctuation as confirmed by small angle X-ray scattering. However, it is found that dipole interaction between water and MeCN is dominant at interface by oxygen K-edge X-ray absorption in combination with density functional theory calculations, which show changes due to interfacial water directly interacting with MeCN.

Keywords: Applied Physics.
Advisor: Doniach S. primary advisor. Thesis advisor
Nilsson Anders
Lindenberg Aaron Michael advisor. Thesis advisor
The zero-pole transformation noise reduction technique for ultra low-noise charge amplifiers [electronic resource]

This research focuses on the design of ultra low-noise charge amplifiers for use in sensor and photo-detector systems. Charge amplifiers are used in the front-end design of systems that have an input signal in the form of charge or a current pulse. A charge amplifier is used to convert the incoming charge or current to a voltage for further processing. The noise level of a charge amplifier determines the minimum signal that can be measured by the system, as well as its resolution. The objective of this research is to define the optimal flow for the design of a low-noise charge amplifier. The work introduces a zero-pole transformation technique that lowers the noise level of charge amplifiers without introducing much complexity or requiring substantial extra area. A zero-pole transformation charge amplifier has been designed in 0.18 [mu]m CMOS technology and fabricated by National Semiconductor. The theory of the zero-pole transformation technique is validated by the experimental design, the measured results agreeing well with the expected noise reduction based on the theories developed for the proposed method. The experimental zero-pole transformation charge amplifier shows a reduction in 40% in its input-referred noise compared to a basic charge amplifier. The minimum input-referred noise level achieved in the proposed charge amplifier is 102ENC (equivalent noise charge).

Keywords: Electrical Engineering
Advisor: Murmann Boris primary advisor. Thesis advisor
Wooley Bruce A.
Vleugels Katelijn advisor. Thesis advisor
1-D chalcogenide nanomaterials for electronics [electronic resource] : phase-change memory and topological insulators

Chalcogenides are ubiquitous in academia and industry. We focus on chalcogenides for phase-change memory and topological insulators. Phase change memory (PCM) utilizes the resistivity contrast between the crystalline and amorphous phases of certain chalcogenides to store information. Industry is making progress in PCM, which could someday compete with flash memory due to its superior scalability, fast switching and high endurance. In contrast, the field of topological insulators is very young. Topological insulators, bulk insulators with conductive surface states, have attracted great attention since their discovery five years ago. They have exotic properties and are exciting for both fundamental studies and potential applications. Our studies of chalcogenide nanomaterials for PCM and topological insulators provided new insights into these fascinating materials. We developed a method to switch PCM cells inside a transmission electron microscope (TEM), allowing direct correlation of electrical behavior with structural changes. Using this technique, we found that the electrical behavior of Ge2Sb2Te3 lateral phase-change cells depends strongly on the highly variable microstructure of the amorphous domain. In search of new PCM materials, we developed the VLS synthesis of GeTe and Sb2Te3 phase-change nanowires. In situ TEM observation of these nanowires revealed a new switching mechanism via the opening and closing of voids. We also synthesized single-crystalline topological insulator nanoribbons, whose large surface to bulk conduction ratio increases the relative contribution of the surface states. We successfully measured Aharonov-Bohm oscillations in the nanoribbons, thereby observing one of the first electrical signatures of the topological states in this material system.

Keywords: Materials Science and Engineering
Advisor: Cui Yi
Goldhaber-Gordon David
McIntyre P. (Paul)
A Mathic Touch - Using Touch-Screen Computers in Collaborative Algebra-1 Problem Solving

This project aimed to develop a math collaborative tool that works on a Tablet-PC, iPad or other touch-screen device. It focused on middle school algebra students amongst whom collaboration is often hindered by several factors. These include lack of collective focus, waiting for one person to speak, explain or write at a time, group and individual power dynamics as well as uneven platform to present ideas to entire group because of these dynamics. The tool consist of a native application that allows students to engage in conversation during problem solving while logging the process and making it visible to both the students and the teacher. The teacher can then decide on how best to assist individual groups.
The project was motivated by my daily encounter with problem solving amongst young learners who are adopting and using modern technology to complete many daily tasks, but also lack learning applications to match the technologies. The design process involved the user-centered approach and constantly checked with the students and teachers for whom the tool is intended. An initial design study involved assessment of students’ collaboration in two situations; one where collaboration was necessary to complete the task while in the second, collaboration was desirable, but not necessary. The assessment during this study involved the comparison of comprehension levels and grasp of underlying features – surface and deep, of patterns used in the puzzle.

Keywords: math
collaboration
touch-screen
engagement
mobile apps
Thesis
A Metropolis Sampling Method to Assess Uncertainty of Seismic Impedance Inverted from Seismic Amplitude Data

Inversion for geomodeling from data measurement is often ill-posed due to the large model dimension and the sparse, limited, and indirect data measurement, and the solution of the ill-posed inversion is a Posterior Probability Density (PPD) of the models. It is not feasible to represent the PPD due to its large number of dimensions. However one could sample the PPD to assess uncertainty of a modeling property. In this study, a Metropolis sampling method was applied to assess uncertainty of seismic impedance from seismic amplitude data for four synthetic case studies, one base case with single geological scenario and three cases with two geological scenarios, and results were compared to Rejection sampling and Sampling within tolerance.

Keywords:  Department of Energy Resources Engineering
School of Earth Energy &amp; Environmental Sciences
Thesis
Advisor: Caers Jef
A Microvisual Investigation of Viscously Unstable Displacement for CO2 Injection

Increasing concentration of CO2 in the atmosphere has been recognized as the major cause for global warming. Urgent need to reduce green house gas has lead to numerous researches in carbon storage and capture, or CO2 sequestration. Storage of CO2 in deep saline aquifers has received significant attention due to its large capacity and available sites. Understanding CO2 flooding mechanisms and microscopic reservoir events is necessary for predicting storage capacity and mitigation effect of CO2 injection. This research focuses on understanding unstable multiphase flow mechanisms that are relevant for CO2 injection in porous media. Specifically, the effect of favorable and unfavorable viscosity ratio, capillary number, and gravitational forces on the flow dynamics in CO2 injection processes is investigated. The experimental work employs analogous fluid pairs for drainage and imbibition experiments in silicon micromodels. The experimental data are analyzed through image analysis and high-resolution numerical simulation. Current macroscopic and pore-scale results both show a stable displacement under favorable viscosity and density conditions and the presence of fingering and a “sparkly” front under unfavorable viscosity condition. The image analysis results show a larger viscosity ratio leads to poor sweep efficiency for drainage experiments. The initial simulation results confirm the findings for stable drainage displacement. The comparison of finger pore lengths for unstable displacements with previous literature sources shows a consistency between the macroscopic observations and the pore-scale trends.

Keywords:  Department of Energy Resources Engineering
School of Earth Energy &amp; Environmental Sciences
Thesis
Advisor: Kovscek Anthony R.
Castanier Louis