VictorJuiz/thesis huggingface dataset:
Welfare fraud, citizenship, and resistance [electronic resource] : Israeli women's attitudes towards workfare ideology
Keywords: Law.

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.
When does gender matter? Gender segregation in the professions of medicine, teaching and law [electronic resource]
Keywords: Sociology.

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.
Why are Some Diversified U.S. Equity Funds Less Diversified Than Others? A Study on the Industry Concentration of Mutual Funds
Keywords:  Department of Economics
Stanford Department of Economics
United States
equity fund managers
fund concentration
Thesis

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.
Wyner-Ziv coding of video [electronic resource]
Keywords: Electrical Engineering

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.
X-ray spectroscopy and scattering study on aqueous solutions of small organic molecules [electronic resource]
Keywords: Applied Physics.

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.
X-ray study of ice and water on surfaces and in aqueous solutions [electronic resource]
Keywords: Chemistry.

Since antiquity, water has been considered as the most important substance on Earth. In fact, the abundance of liquid water on this planet allowed for the emergence and evolution of life. At the molecular level, the structure of an individual water molecule may seem simple; however, the intermolecular interaction between water molecules in the form of hydrogen bonding gives rise to water's various properties that can be considered anomalous when compared to other liquids. In this dissertation, several synchrotron x-ray techniques were used to investigate water in its liquid and solid phases in terms of its structure in and interaction with different model systems that mimic the environments in which water is usually found in nature. First, the effect of ion solvation on the local structure of water was explored using x-ray absorption spectroscopy (XAS) and small angle x-ray scattering (SAXS). There is a charge density dependence of the ability of cations in the restructuring of the water molecules in their vicinity. The monovalent Na+ tends to weaken H-bonds between water molecules, while the divalent Mg2+ and trivalent Al3+ form stable, highly ordered, high-density hydration shells. Fluoride (F-) anion was found to act as a nucleation site for the formation of tetrahedral, low-density structures in liquid water due to its ability to form H-bonds with water, similar to the effect of temperature decrease. XAS spectra of alkali halide solutions confirm that all alkali cations break water-water H-bonds to a varying degree while Cl- and Br- have no distinguishable effect on water and I- tends to break H-bonds. Second, the structure of water confined in AOT reverse micelles was studied using x-ray Raman scattering spectroscopy (XRS), which shows spectral changes that are indicative of an increasing fraction of weakened/distorted H-bonds. Third, the effect of ice adsorption on the electronic structure of hydrophobic methyl-terminated Si(111) surface was studied by C 1s XAS. Despite macroscopic observations of hydrophobicity (i.e. the formation of three-dimensional ice clusters on the surface to maximize water-water H-bonding and minimize surface-water interaction), water molecules were found to directly interact with and increase the asymmetric character of the excited state orbitals of the methyl groups. Finally, x-ray photoelectron spectroscopy (XPS) and XAS were used to study the growth and structure of ice on Pt(111). Pt 4f and O 1s XPS spectra show that the crystalline ice prepared by isothermally heating amorphous ice on Pt(111) forms three-dimensional crystallites, and a significant area of the first monolayer on Pt(111) is exposed to vacuum even at relatively high total coverages. In addition, experimental data from XAS and infrared reflection absorption spectroscopy (IRAS) confirm that the free OH groups on the surface of ice give rise to the XAS pre-edge feature, but there are also contributions from disordered H-bonding in bulk ice, likely due to the presence of various phases of amorphous ice.
The zero-pole transformation noise reduction technique for ultra low-noise charge amplifiers [electronic resource]
Keywords: Electrical Engineering

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).
1-D chalcogenide nanomaterials for electronics [electronic resource] : phase-change memory and topological insulators
Keywords: Materials Science and Engineering

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.
A Mathic Touch - Using Touch-Screen Computers in Collaborative Algebra-1 Problem Solving
Keywords: math
collaboration
touch-screen
engagement
mobile apps
Thesis

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.
A Metropolis Sampling Method to Assess Uncertainty of Seismic Impedance Inverted from Seismic Amplitude Data
Keywords:  Department of Energy Resources Engineering
School of Earth Energy &amp; Environmental Sciences
Thesis

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

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.
A probabilistic framework for synapse localization and class discovery in the mouse whisker barrel cortex
Keywords: Computer Science.
Neural computation
Artificial intelligence
Neural circuitry
Hoefer Prize for Writing in the Major
Thesis

A thorough understanding of the brain's diverse molecular architecture and complex neural circuitry is critical to uncovering the mechanisms that underlie higher-level information processing. Synapses are an integral component of neural circuits because they propagate signals from one neuron to the next. However, because of the astounding multitude and diversity of synapses in the brain, a set of high-resolution, high-precision tools is necessary for extracting enough information from a tissue sample to recover its synaptic structure. To this end, many state-of- the-art molecular imaging methods, including array tomography, have recently focused their efforts on building large-scale datasets annotated with synaptic tissue markers. Manual processing of these images, however, is too time-intensive to be practical. Here, we present a computational method for synapse detection and classification that aims to locate and characterize all synapses in a mouse barrel cortex. Our technique uses a nonparametric Bayesian network to represent the underlying biological process in order to allow for flexibility in the total numbers of synapses and
synapse types that are found. Using this data-driven approach, we are able to detect subtle but significant patterns with implications for neuroscience research.
A Righteous Collusion: The Prisoner’s Dilemma and the Civil Rights Act
Keywords:  Department of Economics
Stanford Department of Economics
employment discrimination
American South
Civil Rights Act
prisoner’s dilemma
Thesis

Various attempts have been made to explain the sources of long-term discriminatory activity – behavior which does not seem to be profit-maximizing, and yet persists in the face of market competition. Research interest has focused on the effect of Title VII of the Civil Rights Act, and whether it has served to decrease employment discrimination or merely exposed firms to costly litigation. Following in the footsteps of Becker (1957), this paper develops a model of employment discrimination that arises as the result of consumer preference as opposed to employer or employee tastes. It predicts that many or all firms in a local industry will conspire to halt discriminatory activity simultaneously during periods of rising costs to discrimination, effectively forming a type of cartel. I perform an empirical test based on employment data collected in the period following the passage of the Civil Rights Act. The results provide suggestive evidence of the model’s validity, and confirm the importance of viewing the question of discrimination through a regional lens.
Achieving clarity on value [electronic resource]
Keywords: Management Science and Engineering.

Decision analysis is the pursuit of clarity of action, and lies at the intersection of action and thought. Before moving to clarity of action, we need to achieve clarity of thought on our values so that we can make decisions that are consistent with our deepest values. This dissertation focuses on helping decision-makers achieve such clarity by suggesting frameworks to discover, appreciate and communicate sources of value. Apart from the theoretical contributions, several case studies are presented to illustrate the use of such methods to achieve consistent valuation and aid mutual understanding on value.