VictorJuiz/thesis huggingface dataset:
Essays on crime and discrimination [electronic resource]
Keywords: Economics

This dissertation consists of three essays. "The Visible Hand: Race and Online Market Outcomes" (with Luke C.D. Stein) considers the results of a year-long online field experiment testing the effects of a seller's race on market outcomes. We find that black sellers receive fewer offers and lower bids, but that results differ across market types. "The Effects of DNA Databases on Crime" provides the first rigorous empirical evidence of the impact of DNA databases on crime. By increasing the probability of catching repeat offenders, increasing the size of a state DNA database decreases several crime rates. Based on the individual-level analysis, this effect appears to be driven primarily by incapacitation, not deterrence. "Under the Cover of Darkness: The Effect of Daylight Saving Time on Violent Crime" (with Nicholas J. Sanders) tests the hypothesis that shifting an hour of daylight from (low-crime) morning hours to (high-crime) evening hours reduces violent street crime such as robbery. We find that robbery rates fall by about 36% during the treated hour, without a corresponding increase at other times.
Essays on dynamic mechanism design [electronic resource]
Keywords: Economics

This dissertation advocates dynamic mechanism design as a useful tool to tackle theoretical challenges in microeconomics and to solve real world institutional design problems. It is composed of two chapters. In the first chapter, I study durable goods sales with a dynamic population of buyers. My contribution is to devise a Multi-round Simultaneous Ascending Auction with Generalized Reserve Price (MSAAGR) to implement the efficient allocation, and to contrast MSAAGR with the standard uniform price auction to highlight the implication of population dynamics on the design of trading platforms. In the second chapter, I estalibsh the possibility of sustaining long-term cooperation in infinitely repeated private monitoring games with scarce signals. My contribution is to construct a novel Budget Mechanism with Cross-Checking (BMCC) which, by linking players' action choices over time, virtually implements the efficient outcome with a vanishing incentive cost as the horizon of the game grows and the players become increasingly patient.
Essays on financial market structure and design [electronic resource]
Keywords: Business.

In this doctoral dissertation, I study financial market structure and design, namely how institutional features of financial markets affect price discovery, liquidity, search behavior, efficiency, and welfare. This dissertation consists of three chapters. The first chapter studies dark pools and price discovery. Dark pools are equity trading systems that do not publicly display orders. Orders in dark pools are matched within the exchange bid-ask spread without a guarantee of execution. Because informed traders tend to have common information regarding the asset value, they are more likely to cluster on the heavy side of the market and therefore face a lower execution probability in the dark pool, relative to uninformed traders. Consequently, exchanges are more attractive to informed traders, whereas dark pools are more attractive to uninformed traders. Under natural conditions, adding a dark pool alongside an exchange concentrates price-relevant information into the exchange and improves price discovery. The second chapter offers a dynamic model of opaque over-the-counter markets. I build a theoretical model of OTC markets, in which a seller searches for an attractive price by visiting multiple buyers, one at a time. The buyers do not observe contacts, quotes, or trades elsewhere in the market. A repeat contact with a buyer reveals the seller's reduced outside options and worsens the price offered by the revisited buyer. When the asset value is uncertain and common to all buyers, a visit by the seller suggests that other buyers could have quoted unattractive prices and thus worsens the visited buyer's inference regarding the asset value. This chapter is now published at the Review of Financial Studies, Volume 25, Issue 4, April 2012. The third chapter studies settlement auctions for credit default swaps (CDS). This chapter is the joint work with Songzi Du, a fellow Doctoral Candidate at the Graduate School of Business, Stanford University. We find that the one-sided design of CDS auctions used in practice gives CDS buyers and sellers strong incentives to distort the final auction price, in order to maximize payoffs from existing CDS positions. Consequently, these auctions tend to overprice defaulted bonds conditional on an excess supply and underprice defaulted bonds conditional on an excess demand. We propose a double auction to mitigate this price bias. We find the predictions of our model on bidding behavior to be consistent with data on CDS auctions.
Essays on information in options markets [electronic resource]
Keywords: Business.

In the first chapter, my coauthor and I examine the information content of option and equity volumes when trade direction is unobserved. In a multimarket asymmetric information model, equity short-sale costs result in a negative relation between relative option volume and future firm value. In our empirical tests, firms in the lowest decile of the option to stock volume ratio (O/S) outperform the highest decile by 0.34% per week (19.3% annualized). Our model and empirics both indicate that O/S is a stronger signal when short-sale costs are high or option leverage is low. O/S also predicts future firm-specific earnings news, consistent with O/S reflecting private information. In the second chapter, I show that in many asset pricing models, the equity market's expected return is a time-invariant linear function of its conditional variance, which can be estimated from options markets. However, I show that when the relation between conditional means and variances is state-dependent, an observer requires the combined information in multiple variance horizons to distinguish among the states and thereby reveal the equity risk premium. Empirically, I show that while the VIX by itself has little predictive power for future S& P 500 returns, the VIX term structure predicts next-quarter S& P 500 returns with a 5.2% adjusted R-squared.
Essays on matching theory [electronic resource]
Keywords: Economics

This dissertation consists of four essays on matching theory. The first two essays, which are presented in Chapters 2& 3, investigate two different manipulation channels in school choice problems. The last two essays, which are presented in Chapters 5& 6, employ the hospital-intern matching market model. While I introduce and investigate a new manipulation tool in Chapter 5, the last essay studies the welfare effects of pre-arrangements.
Evaluating the Federal Food Assistance Safety Net: Do low-income individuals experience larger decreases in nutrient intakes during economic downturns than their wealthier counterparts?
Keywords:  Department of Economics
Stanford Department of Economics
Nutrition
low-income
food security
high unemployment
WIC
SNAP
Thesis

Low-income households often have less nutritious diets when compared to their wealthier counterparts due to decisions maximizing calories and minimizing costs. However, current research has not focused on whether gaps in nutritional intakes between different income groups have widened during periods of higher unemployment or whether food assistance programs protect the poor during these times. Using data from National Health and Nutrition Examination Survey and the Bureau of Labor Statistics ranging from 1999 to 2010, I conducted difference-in-difference tests to determine if low-income individuals experience a larger decrease in key nutrient levels and health indicators during economic downturns than richer counterparts. I found that higher periods of unemployment (proxy for worse economy) had mostly positive effects on adults living below 1.25 times the poverty level, as they increased total calories, fiber, vitamin C, vitamin E, magnesium, and potassium, while unfortunately elevating sugars, carbohydrates, and triglycerides. Interestingly, individuals above three times the poverty level had less protein, fiber, B vitamins, and other minerals during tougher economic periods, while the very wealthy tended to substitute towards unhealthier diets with more calories, fats, and sugars. Results for children also followed similar trends, as low-income groups improved key vitamin intakes while high-income groups moved towards more energy dense diets. A difference-in-difference-in-differences analysis showed that adult participation in the Women, Infants, and Children (WIC) program led to an increase in several key vitamins, cholesterol, and sodium; however, enrollment in the Supplemental Nutrition Assistance program (SNAP) was only shown to have indirect effects. With my preliminary results, I advocate an increase in WIC funding, a re-examination of SNAP, and a shift towards subsidizing more nutritious, healthy options.
Evidence for an excess of B -> D(*) Tau Nu decays [electronic resource]
Keywords: Applied Physics

Based on the full BaBar data sample, we report improved measurements of the ratios R(D(*)) = B(B -> D(*) Tau Nu)/B(B -> D(*) l Nu), where l is either an electron or a muon. These ratios are sensitive to new physics contributions in the form of a charged Higgs boson. We measure R(D) = 0.440 +- 0.058 +- 0.042 and R(D*) = 0.332 +- 0.024 +- 0.018, which exceed the Standard Model expectations by 2.0 sigma and 2.7 sigma, respectively. Taken together, our results disagree with these expectations at the 3.4 sigma level, which could be an indication of beyond-the-Standard- Model processes affecting these decays. We examine whether the excess in R(D) and R(D*) could be explained by a charged Higgs boson in the type II two-Higgs-doublet model, which describes the Higgs sector of the Minimal Supersymmetric model at tree level. We exclude this possibility in the full parameter space with a probability of at least 99.8%, or 3.1sigma significance. We also report the observation of the decay B -> D Tau Nu, with a significance of 6.8 sigma.
The evolution and demography of X-linked and GWAS SNPs [electronic resource]
Keywords: Genetics

Population geneticists have used genome-wide single nucleotide polymorphism (SNP) datasets to investigate the demographic history of humans and to identify regions of the human genome subject to selection. While some general statements can be made about genome as a whole, every genomic locus has its own evolutionary history. The work contained in this dissertation is aimed at elucidating this history for two particular SNP subsets. The first two chapters explore the effects of selection on the X chromosome. Chapter 1 presents evidence that the X chromosome is more frequently a target of selection than the autosomes and identifies regions of the chromosome where selection may have acted. Chapter 2 explores the evolutionary history of one of these regions in depth through haplotype analyses. Chapter 3 investigates the role of selection in the evolution of SNPs with phenotypic associations and finds evidence for selection on SNPs associated with pigmentation, blood pressure, autoimmune disease, and infectious disease susceptibility. Overall, this work as a whole reinforces the conclusion that natural selection acts unevenly throughout the genome and presents evidence for selection on two subsets of genome-wide SNP datasets: X-linked SNPs and SNPs with phenotypic associations.
Examining an unexpected protective role of amyloid-beta in experimental autoimmune encephalomyelitis [electronic resource]
Keywords: Neurology.

[Beta]-amyloid-42 (A[beta]42) and [beta]-amyloid-40 (A[beta]40), major components of senile plaque deposits in Alzheimer's disease (AD), are considered neurotoxic and pro-inflammatory. In Multiple Sclerosis (MS), A[beta]42 is upregulated in brain lesions and damaged axons. Here we found, unexpectedly, that treatment with either A[beta]42 or A[beta]40 peptides reduced motor paralysis and brain inflammation in four different models of experimental autoimmune encephalomyelitis (EAE) with attenuation of motor paralysis, reduction of inflammatory lesions in the central nervous system (CNS), and suppression of lymphocyte activation. A[beta]42 and A[beta]40 treatments were effective in reducing ongoing paralysis induced with adoptive transfer of either autoreactive Th1 or Th17 cells. High-dimensional 14-parameter flow cytometry of peripheral immune cell populations after in vivo A[beta]2 and A[beta]40 treatment revealed substantial modulations in the percentage of lymphoid and myeloid subsets during EAE. Major pro-inflammatory cytokines and chemokines were reduced in the blood following A[beta] peptide treatment. Protection conferred by A[beta] treatment did not require its delivery to the brain: adoptive transfer with lymphocytes from donors treated with A[beta]42 attenuated EAE in WT recipient mice and A[beta] deposition in the brain was not detected in treated EAE mice by immunohistochemical analysis. In contrast to the improvement in EAE with A[beta]-treatment, EAE was worse in mice with genetic deletion of the amyloid precursor protein. Therefore, in the absence of A[beta] there is exacerbated clinical EAE disease progression. Since A[beta]42 and A[beta]40 ameliorate experimental autoimmune inflammation targeting the CNS, we might now consider its potential anti-inflammatory role in other neuropathological conditions.
Experimental determination of rate constants for reactions of the hydroxyl radical with alkanes and alcohols [electronic resource]
Keywords: Mechanical Engineering

Over one quarter of the energy usage in the United States currently occurs in the transportation sector. Improvements in energy conversion efficiency and sustainability in transportation applications, therefore, can substantially contribute to improved energy security in our future. The design of advanced high-efficiency energy conversion devices for transportation applications can be facilitated with complex computer models of combustion processes. The development of these models requires a large experimental database to ensure accuracy of the computational predictions. This thesis discusses how experimental studies are utilized to create a database of rate constants for elementary reactions; these rate constants are integral components of any computational model of combustion chemistry. During a combustion process, the reaction of the hydroxyl (OH) radical, a highly reactive chemical intermediate, with a combustible fuel molecule is a major fuel consumption pathway under many combustion conditions. Thus, the rate constants for these types of reactions must be accurately known to develop a computational model that correctly describes the combustion chemistry. This thesis presents an experimental method for measuring rate constants in the reaction family of OH + Fuel -> Products using a shock tube reactor, laser diagnostics, and tert-butylhydroperoxide (TBHP) as an OH radical precursor. Important rate constant parameters describing subsequent reactions of TBHP decomposition are also studied. Current transportation fuels of interest in the combustion community include molecules in the alkane and butanol classes. Alkane molecules are a major component of many petroleum-derived fuels such as gasoline and jet fuel. Isomers of the butanol molecule are gaining popularity as a potential renewable alternative to gasoline because of their high energy density and the many known methods of production from biomass and agricultural byproducts. The rate constant measurement method is applied to the reaction of OH with three alkane molecules (n-pentane, n-heptane, and n-nonane) and four isomers of butanol (n-butanol, iso-butanol, sec-butanol, tert-butanol), and the results are reported in this thesis. Comparison of the rate constant results to estimation methods in the literature are presented, and, for several of the isomers of butanol studied, the measured data are also used to validate and/or suggest refinements to existing detailed kinetic mechanisms.
Experimental study of vacuum microplasma spraying [electronic resource]
Keywords: Mechanical Engineering

Vacuum plasma spraying (VPS) is an industrial process for depositing coatings of metal or ceramic in order to impart surface properties to an underlying part, or to build freestanding parts. High-value coatings of high melting point, oxidation-sensitive materials for applications such as aerospace components or biomedical implants are enabled by the vacuum process. Commercially available VPS systems operate at arc power levels of 40--120 kW and with deposition rates of 25¬--50 g/min. In recent years, the plasma spray community has developed interest in scaling down such systems to reduce the cost of small-scale applications and/or for novel applications enabled by lower deposition rates. The work of this dissertation is the first published account of vacuum microplasma spraying (VMPS), operating at arc power levels of 1--2 kW and deposition rates of 0.1--1 g/min. The dissertation documents the design, construction, and testing of the VMPS system, by means of decomposition into subprocesses. For subprocess 0 (powder delivery to the plasma jet), the work entailed development of a novel powder feeder. For subprocess 1 (arc discharge and nozzle flow), a supersonic plasma nozzle with internal powder injection was developed and tested. Flow, calorimetric, and pressure measurements in the nozzle are presented and incorporated into a thermodynamic model for the plasma generated by the arc discharge. For subprocess 2h (plasma--particle heat transfer), a novel "surrogate particle" heat transfer measurement was developed and used to evaluate heat transfer rates to sprayed particles. In conjunction with finite element modeling of convection and radiation to the particle, these experimental data were used to estimate required residence time for sprayed particles of various metals. For subprocess 2m (plasma--particle momentum transfer), a planar laser Mie scattering system was employed for imaging and tuning of particle trajectories, and a particle image velocimetry (PIV) system was used to determine particle velocities and residence times. Final recommendations include the use of smaller particle diameters in order to enhance melting behavior in these low-power plasma jets. The system is capable of depositing challenging, high-value metals and ceramics. With expected improvements from particle size reduction, it is prepared for advanced applications.
An experimental test of the effect of norm-referenced and criterion-referenced feedback on just world beliefs, motivation, and performance [electronic resource] : does social disadvantage matter?
Keywords: Education.

The just world beliefs, self-reported commitment to long-term academic goals, time spent studying, and change in performance after receiving norm-referenced, criterion-referenced, and control feedback were compared. Students from two high schools in Northern California serving lower middle and upper middle class populations respectively took a difficult math test and were provided with failure feedback based on either a norm-referenced, criterion-referenced, or non-referenced standard. Participants were offered an opportunity to study before they took a second difficult math test. For socially disadvantaged students (as indicated by mother's highest level of education), norm-referenced feedback resulted in significantly less time studying for the second test. In addition, a significant interaction between level of social disadvantage and type of feedback on change in performance is revealed. In particular, norm-referenced feedback is found to have a significant negative effect on the change in performance of disadvantaged students and a significant positive effect on the change in performance of advantaged students. While feedback type did not significantly affect student just world beliefs, a relationship between just world beliefs and time spent studying that is moderated by level of social disadvantage is revealed. The results add to the literature by generalizing findings from previous research to a different population and to different measures of just world beliefs and motivation suggesting a potential developmental component to the relationship between just world beliefs and motivation. The research also sheds new light on how norm-referenced feedback differentially affects student outcomes depending on level of social disadvantage.
Explicitly filtered large-eddy simulation [electronic resource] : with application to grid adaptation and wall modeling
Keywords: Mechanical Engineering

The governing equations for large-eddy simulation (LES) are derived from the application of a low-pass filter to the Navier-Stokes equations. LES has shown to be a tractable method for the computation of high Reynolds number turbulent flows, primarily because the filtration of the Navier-Stokes equations removes the small scales of motion that would otherwise impose prohibitive resolution requirements. The effect of the scales of motion that are smaller than the filter width on the large, resolved scales are then modeled. In practice, the filter used to derive the LES governing equation is not formally defined and instead, it is assumed that the discretization of LES equation will implicitly act as a low-pass filter. This study investigates an alternative derivation of the LES governing equations that requires the formal definition of the filtration operator, known as explicitly filtered LES. It is shown that decoupling the filtering operation from the underlying grid allows for the isolation of subgrid-scale (SGS) modeling errors from numerical discretization errors. In this grid-independent context, it is demonstrated that standard eddy viscosity models are inaccurate at coarse resolutions. By leveraging the definition of the filtering operator, an SGS model is subsequently derived from a low order perturbation of the explicitly filtered governing equations. LES of canonical wall bounded flows (e.g., channels and ducts) at coarse resolutions validate the improved accuracy of the proposed SGS model. Simulations of practical engineering configurations require the ability to handle complex geometries. Previous explicitly filtered LES calculations have been limited to structured grid discretizations because of the difficulty in constructing a low-pass filter on unstructured grids. The explicitly filtered framework and the proposed SGS model are extended for use in unstructured grid environments through the use of differential filters. Unstructured grids also provide the ability to locally increase resolution in regions of the flow where the SGS model is unable to accurately model the stress provided by the unresolved scales of motion. A novel adaptation technique is suggested where the mesh (and/or filter) is refined in regions of the flow where estimates of the SGS fluctuations are largest. An LES of a three-dimensional stalled diffuser is performed to demonstrate the efficacy of the SGS model based mesh refinement criteria and the capabilities of the differential filters on unstructured grids. Lastly, a dynamic wall boundary condition is derived from the differential filter for wall-modeled large-eddy simulation where the near wall turbulence is not resolved. This differential filter based wall model successfully predicts mean dynamics of both wall-bounded flows (channels) and separating flows in complex geometries (airfoil at near-stall conditions) without the prescription of any ad hoc coefficients or RANS/LES hybridization.