VictorJuiz/thesis huggingface dataset:
MBA Job Placement And Stock Market Performance
Keywords:  Department of Economics
Stanford Department of Economics
Abnormal Returns
Human Capital
Risk Modeling
Corporate Investment
Job Placement
Thesis

Firms that hire MBA graduates from two prominent MBA programs, consistently ranked in the top 10, exhibit abnormally high risk-adjusted stock returns in months leading up to hiring. This paper tests three factors that could explain this phenomenon: self-selection of the MBA graduate, selfselection of hiring firms, and underestimation of risk in firms undergoing expansion. The paper finds the most likely causes of the phenomenon to be the self-selection of hiring firms and the underestimation of firm risk as measured by market beta.
Measurements and technology for long-term neural prosthetic systems [electronic resource]
Keywords: Electrical Engineering

Cortical brain-machine interfaces, or BMIs, is a relatively new field with the potential to provide many different clinical treatments, particularly for fully paralyzed patients. In these applications, multichannel electrode arrays are implanted into motor cortical areas in order to extract useful control signals. My research focuses on taking proof-of-concept academic BMI systems, and solving the engineering challenges that currently prevent them from being used in a clinical setting. These challenges include running a BMI for more than a few hours or a single day, and finding ways to minimize the size, cost, and operational complexity of the complete system. This dissertation includes an analysis of neuron stability over long timescales. I will show that the relationship between neurons in motor cortices and behavior remains stationary over time despite substantial noise, which could mitigate some concerns about long-term BMI performance. I will also discuss the development of HermesC, a wireless system for recording multichannel neural data from freely moving primates. This device dramatically reduces the size and cost of current recording technology for real-time neural prosthetic systems, and could be useful for human clinical trials. It may also enable neural prosthetic studies with animals in a less constrained setting. Combining traditional neural recordings with overnight wireless neural recordings, I will also show that there are substantial changes in neural waveforms from single neurons across days. However, the quality of neural decodes (the extraction of useful control signals) is only slightly improved by sorting individual units rather than using simple threshold crossings. This may enable long term BMI operation because multiunit neural "hash" on electrode arrays tends to persist for a long time, perhaps years, after single neuron signals have declined due to various tissue responses. In fact, other recent work from this project has demonstrated high performance neural decodes using only threshold crossings on arrays ~2.5 years after implantation.
Measurements of B -> V gamma decays [electronic resource]
Keywords: Physics

Observational evidence and theoretical motivation have led us to the conclusion that our current understanding of the universe is incomplete. While new physics is expected to exist above the electroweak scale, its influence can be detected by experiments that operate below this scale. The Babar experiment has recorded approximately 432 fb-1 of data at the center of mass energy of 10.58 GeV, which corresponds to the Y(4S) mass. One of the physics programs is studying radiative decays of the B meson. These decays primarily proceed through loop diagrams, and thus influences of new particles may be detectable. In this thesis, I present results of the measurements of the branching fractions, CP asymmetry, and isospin asymmetry of B -> K* gamma. Results are also presented for the measurements of the branching fractions of B -> rho(omega) gamma. Finally, a search for the decay of B -> phi gamma is given.
Measurements of direct CP violation and constraint on the CKM triangle in B->K*pi decays [electronic resource]
Keywords: Physics

We constrain the apex of the Cabibbo-Kobayashi-Maskawa unitarity triangle with measurements of B-> K*pi amplitudes from analyses of B0-> K+pi-pi0 and B0-> K_Spi+pi- decays. This constraint is consistent with the world average. The B0-> K+pi-pi0 decay mode is reconstructed from a sample of 454 million B0B0bar events collected by the BABAR detector at SLAC. We measure direct CP violation in B0-> K*+pi- decays at the level of 3 sigma when measurements from both B0-> K+pi-pi0 and B0-> K_Spi+pi- decays are combined.
Measuring Japan's nursery quality within the UNCRC framework [electronic resource] : international standards for young children's social services and their implications for Japan
Keywords: Law.

In response to mounting concerns regarding the decline in birthrate in Japan and the increasing aged population, center-based daycare has assumed an important role in Japanese society. In order to tackle the issues of low birthrate and longevity, demand for policies that encourage women to both participate in the workforce and have children is greater than ever. Since 1997, this perceived need has brought about a policy transformation in Japan's postwar system of approved nursery centers (i.e., nursery facilities that meet the national daycare quality standards), which had—until then—operated measures entirely under the control of the municipalities, as part of the child welfare policy of the Japanese government. In order to respond to the urgent need for daycare services and facilities, the government has instigated a policy of privatization throughout its nursery centers system and has relaxed many of the regulations in the field of daycare services provision. However, in the course of the privatization of public nursery centers, the government has been widely regarded as prioritizing "capacity (quantity)" concerns over "quality" concerns when constructing its policies. Because the nursery centers system has undergone legal reform and because quality concerns are on the rise, both researchers and administrative officers have come to recognize how important it is to define and measure quality nursery daycare. With this issue in mind, this study proposes an approach to assess the quality of Japan's nursery daycare against international standards, particularly from the standpoint of a state party's obligations under the 1989 United Nations Convention on the Rights of the Child (UNCRC). The following research questions are central to this study: To what extent does Japan comply with international standards on daycare quality? Are there international standards that Japan should be permitted exemptions from, and if exemptions are appropriate, what is the rationale for such exemptions? This study is the first detailed examination of Japan's nursery daycare policies under the framework of the UNCRC written in English. The introduction of a daycare quality assessment method to Japan—one that is based on international standards—serves as a useful basis both for the smooth formulation and implementation of nursery policies that ensure daycare provisions (in terms of quantity and quality) and to provide a benchmark against which reasonable judicial rulings can be made on the basis of the "the best interests of the child, " one of the core principles in the UNCRC. Furthermore, it will also help provide some insights into how stakeholders of nursery daycare in OECD countries are able to ensure that daycare quality takes children's best interests into account while also considering the historic, cultural, and social contexts of respective countries.
Mechanisms for delivering hydrogen from ammonia-borane via protons, hydrides, and a dative bond [electronic resource]
Keywords: Chemical Engineering

The hydrogen economy is a hypothetical replacement for the world's reliance on fossil fuels. Concerns over carbon dioxide and global warming have driven research into creating reliable systems to utilize hydrogen as a vehicular fuel. Because molecular hydrogen is a gas, storage at practical densities is a major problem for its utilization. One highly promising material for hydrogen storage is ammonia-borane (AB), or NH3BH3. AB has a high weight percent hydrogen (~20%) and its protic (N-H) and hydridic (B-H) hydrogens appear ripe for dehydrogenation. However, reversible release of H2 from AB requires fine control over dehydrogenation mechanisms. Using ab initio simulations, we elucidate the fundamental mechanisms involved in removing hydrogen from AB. Herein, we investigate mechanisms for the dehydrogenation of AB by homogeneous catalysis and thermolysis. We show that unexpected active catalysts and experimentally unobservable intermediates are key aspects of this chemistry. Furthermore, the effects of solvent and dynamics are vital to understanding product distributions. Finally, two-hydrogen transfer is highlighted as a fascinating chemistry involving the simultaneous transfer of protic and hydridic hydrogen.
Mechanisms of deep brain stimulation revealed by optogenetic deconstruction of diseased brain circuitry [electronic resource]
Keywords: Neurosciences.

Deep brain stimulation (DBS) is a powerful therapeutic option for intractable movement and affective disorders (Parkinson's disease or PD, tremor, dystonia, Tourette syndrome, chronic pain, obsessive compulsive disorder, depression, bipolar). The benefits of DBS are immediate and dramatic, manifested as instantaneous improvements in motor function in the case of PD patients. However, due to the nonspecificity of electrical stimulation, DBS has variable efficacy and can lead to serious side effects. The mechanisms behind the effects of DBS are still highly controversial and there is tremendous interest from both neuroscience and clinical communities to understand and improve DBS. We have developed a novel technology based on two microbial opsins, Channelrhodopsin (ChR2) and Halorhodopsin (NpHR), that allows to directly and specifically control the activity of distinct cell-types with high temporal precision in well defined brain regions, therefore allowing us to overcome the lack of specificity of electrical DBS. This study provides the first investigation of the role of specific cell types in ameliorating PD symptoms addressed by effective DBS treatment. The focus of the thesis was twofold: (1) to develop and optimize optogenetic technologies (molecular and hardware) for safe and effective use in behaving mammals; and (2) to employ the above developed optogenetic toolkit to deconstructing diseased brain circuitry, with focus on Parkinson's disease. The framework and technological toolbox presented here can be employed across many brain circuits to selectively control individual components and therefore systematically deconstruct intact and disordered brain processes.
Mechanistic insights towards new reactions and materials [electronic resource]
Keywords: Chemistry

Catalysis is the enabling science of polymer synthesis, and new catalytic mechanisms yield new materials. The developement of organocatalysts for polymer synthesis has, particularly in the last decade, spawned an impressive array of new catalysts, processes and mechanistic insights. While the focus of most recent research in organocatalysis has concentrated on enantioselective synthesis of small molecules, organocatalysis offers a number of opportunities in polymer synthesis and was among the earliest methods of catalyzing the synthesis of polyesters. The enthalpy of ring opening of cyclic esters or carbonates drives the majority of organocatalyic polymerization reactions catalyzed by a still-evolving array of organocatalysts. Organocatalysts are thought to effect polymerization of cyclic esters by several mechanisms. Some proceed via a monomer activated mechanism whereby the catalyst activates the cyclic ester towards transesterification to the polymer chain. Others operate by an alcohol activation mechanism where the alcoholic end group of the growing polymer chain is activated to induce transesterification. Some are thought to be operative by a combination of these mechanisms. The unique reactivity offered by organocatalysts has provided access to precisely controlled macromolecular architectures and well-defined (co)polymers including a wide array of functionality. The notion that rate must be sacrificed to implement organocatalysts is fading with the discovery of transesterification organocatalysts that rival in reaction rate even the most active metal-containing catalysts. Cyclopentadienyl ruthenium complexes with quinaldic acid-type ligands are robust allylation catalysts in alcoholic solvents, but they are sensitive to dissolved oxygen, requiring reactions to be conducted in an inert atmosphere. Moving from alcoholic to neat aqueous solvents decreases the rate of deallylation but allows the reaction to be conducted in air without loss of catalyst activity over the course of the reaction. These complexes are also effective for the formation of allyl ethers, allowing the synthesis of poly(2,5-dihydrofuran) from the condensation polymerization of 2-cis-butene-1,4-diol. This material was previously deemed inaccessible via traditional polycondensation catalysts.
Mechanobiology of aortic disease in animal models [electronic resource]
Keywords: Bioengineering.

The aorta is the largest blood vessel in the body, responsible for carrying blood from the heart directly to most major organs and ending at the iliac arteries which feed the lower extremities. This elastic vessel provides much of the vascular system's compliance and is composed of a heterogeneous mixture of smooth muscle cells, collagen, and elastin. The general purpose of our work has been to use in vivo imaging to determine abdominal aortic dynamics in a variety of healthy and diseased cases. First, a cross-species analysis in mice, rats, rabbits, pigs and humans showed with M-mode ultrasound that infrarenal abdominal aortic motion was similar in animals and humans, regardless of aortic size. Greater anterior than posterior wall motion was observed and aortic wall displacement increased linearly with diameter. Next, cardiovascular abnormalities in a recently developed mouse model for Williams-Beuren Syndrome (WBS) were investigated. WBS is a rare genetic disorder caused by a heterozygous 1.5-megabase deletion, which typically includes the elastin gene. In this study, we showed that Wbs mice have hypertension, reduced in vivo cyclic strain, and fragmented medial elastin sheets - all characteristics similar to human WBS. These data provide insight into the genotype-phenotype relationship between elastin levels, aortic stiffness, and the cardiovascular abnormalities associated with WBS and other microdeletion syndromes. Finally, the biomechanical influences on murine models of abdominal aortic aneurysms (AAA), a pathological dilation of the abdominal aorta, were investigated using magnetic resonance imaging. From this work, we showed that the location of aneurysm development may be correlated with the location of maximum abdominal aortic curvature in angiotensin II-induced murine AAAs. This model consistently forms abdominal aneurysms with repeatable leftward vessel expansion above the renal arteries. Our work has shown that this leftward saccular shape is likely influenced by leftward suprarenal aortic curvature and motion. Histological analysis provided evidence for degradation of medial elastin at one focal location on the left side of the vessel, with a majority of animals also developing an adventitial hematoma at a similar circumferential location. Conversely, elastase-induced infrarenal murine AAAs do not form in a location of high vessel curvature and do not expand in one general direction. This work will help to further our understanding of the role mechanics may play in AAA formation, progression, and eventual rupture.
Mediated transcendence [electronic resource] : realism and revelation in Russian Fiction, 1863-1898
Keywords: Slavic Languages and Literatures

"Mediated Transcendence: Realism and Revelation in Russian Fiction, 1863-1898" investigates the relationship between literary form and transcendence in representative texts of the Russian Realist tradition. The author identifies scenes of literary transcendence, spanning transformative religious and psychological experiences, as epiphanies, which display a unique confluence of content and form -- at once a narrative event, in the life of the character, and a locus of literary devices. The project proceeds from the premise that the ineffable content of epiphany exceeds the verisimilar parameters of literary realism, and even the semiotic capacity of prose language. In response to this representational problem, the authors analyzed elaborate narrative and poetic strategies for the purposes of framing transcendence, augmenting discursive representation with performative presentation. Beginning with Tolstoy's model of the literary epiphany in War and Peace in the introduction, the dissertation subsequently explores the theme and forms of transcendence in Fyodor Dostoevsky's "The Idiot, " Nikolai Leskov's "The Sealed Angel, " and selected stories of Anton Chekhov. Incorporating elements of theology, phenomenology, and critical theory, these individual readings reveal the aesthetic nature of visionary experience, and the way such experience is conveyed by the appropriately aesthetic means and potential of the literary text. In challenging notions of the empirical and positivist biases of Realism, the dissertation reevaluates the historical position of the movement, indicating its formal and theoretical debt to Romanticism, as well as its subsequent influence on Modernism.
Mental time lines across the world [electronic resource] : how do people think about time in Hebrew, Mandarin, and English?
Keywords: Psychology

Across cultures people rely on space to represent time. However, the particular spatial layout created to represent time differs across cultures, and is affected by different sources of culturo-linguistic experience. In the studies described in this dissertation I focus on two such sources of information; reading directionality and spatial metaphors. First, I show that Hebrew and English speakers consistently arrange temporal sequences in a way that is congruent with their writing directionality, left to right for English speakers, and right to left for Hebrew speakers. Moreover, making judgments about earlier and later events with a key orientation that is incongruent with one's writing directionality (e.g, 'right' for earlier events in the English speaking group) creates interference, and produces slower responses. I then compare English and Mandarin speakers, to see whether the way speakers of these languages think about time reflects the way they habitually talk about it. In Mandarin, vertical metaphors of time are used more frequently and systematically than they are in English. Accordingly, the findings suggest that Mandarin speakers are faster to make temporal order judgments when the 'earlier' key is positioned on top of the 'later' key. English speakers do not show that congruency effect. Overall, the findings presented in this work suggest that culturally specific spatial representations are accessed automatically when people think about time, even in non-linguistic tasks, for temporal sequences that are not usually laid out in space in a particular directionality, and even when space is implicit to the task.
Method for removing hydrogen sulfide from sour-gas and converting it to hydrogen and sulfuric acid [electronic resource]
Keywords: Aeronautics and Astronautics

A method for removing hydrogen sulfide from a sour-gas stream is investigated and found to be promising. The method oxidizes hydrogen sulfide to sulfuric acid by reducing aqueous bromine to hydrobromic acid in solution. Sulfuric acid is concentrated to eliminate its bromine content prior to being removed from the system, while the remaining hydrobromic acid solution is electrolyzed to regenerate aqueous bromine and produce hydrogen. The aqueous bromine solution does not react with hydrocarbon components common to natural gas including methane and ethane. This allows the process to both sweeten sour-gas and convert its hydrogen sulfide content to sulfuric acid in a single step. Specific reactor conditions were found to produce sulfur instead of sulfuric acid. Hydrobromic acid electrolysis requires less than half the energy required by water electrolysis and is an inherently flexible load that can shed or absorb power to balance supply and demand. Thus the electrolysis of hydrobromic acid may provide a route to produce inexpensive hydrogen and improve the electric grid.
Methods and applications of topological data analysis [electronic resource]
Keywords: Mathematics

The focus of this dissertation is the development of methods for topological analysis as well as the application of topological tools to real world problems. The first half of the dissertation focuses on an algorithm for de-noising high-dimensional data for topological data analysis. This method significantly extends the applicability of many topological data analysis methods. In particular, this method extends the use of persistent homology, a generalized notion of homology for discrete data points, to data sets that were previously inaccessible because of noise. The second half of this dissertation focuses on a method for using topology to simplify complex chemical structures and to define a metric to quantify similarity for use in screening large databases of chemical compounds. This method has shown very promising initial results in locating new materials for efficiently separating carbon dioxide from the exhaust of coal-burning power plants.
Methods for the wafer-scale encapsulation of MEMS [electronic resource]
Keywords: Mechanical Engineering

The packaging of microelectromechanical systems (MEMS) is one of the most important design considerations in taking a product from a research environment to a commercial application. It must not only provide a suitably clean and stable environment for the device, but it should also withstand any harsh post-processing steps (such as wafer dicing and wire bonding) needed to integrate the device into its final system. As a result, the cost of packaging is typically a large portion of the overall cost of any commercial MEMS product. Addressing these needs for electrostatic silicon MEMS, this work describes the development of multiple wafer-scale encapsulation techniques that allow for a wide range of devices to be fabricated in a single fabrication process. Expanding on the thin film, 'epi-seal' encapsulation technique developed jointly by Stanford University and Bosch, a packaging method was developed that makes use of a thick sacrificial oxide deposition and subsequent planarization to allow for large lateral deflection structures side-by-side with proven narrow gap devices, such as tuning fork resonators. In an effort to further increase the capabilities of wafer-scale encapsulation, a process combining fusion wafer bonding and epitaxial reactor sealing was also developed. Unlike many packaging techniques using wafer bonding, the overall package size is only slightly bigger than the device itself and results in a stable, clean environment for the device. The final encapsulated part consists of a single crystal silicon structure free of native oxide inside a single crystal silicon cap layer. In addition, this encapsulation can support numerous process variations, such as oxide-coated composite device structures and the first MEMS devices packaged at the wafer scale using the surface migration of silicon atoms.