VictorJuiz/thesis huggingface dataset:
Development Assistance for Health as a Weapon Against Threats of Infectious Diseases: Evidence from aid for HIV and Tuberculosis
Keywords:  Department of Economics
Stanford Department of Economics
provider interest
aid allocation
development assistance for health
public health
Thesis

Prior research on allocation of development assistance (DAH) for health has focused primarily on recipient need, and not on provider interest. Provider interests, in the form of financial or welfare benefits, can influence donor behavior by affecting prioritization of goals or modifying aid amounts. Shiffman (2006) proposes that funding for HIV and tuberculosis have risen disproportionately because of their burden on industrialized countries, while funding for malaria – a tropical disease – has remained relatively low. Of many possible forms of provider interest, this paper focuses on the incentives of the donor states to protect the public health of its own residents by allocating DAH to the control of infectious diseases abroad. If this incentive does exist, I expect the DAH amount for a disease to increase with the domestic prevalence of the disease in the donor country. I use a multiple regression strategy to estimate the effect that prevalence has on DAH allocated per year to HIV and tuberculosis from 1990 to 2009. My analysis provides evidence that HIV and TB prevalence in donor country positively affects international health aid granted for those diseases.
Development of a diode laser sensor for measurement of mass flux in supersonic flow [electronic resource]
Keywords: Mechanical Engineering

Mass flux is one of the most critical parameters in the calculation of engine thrust and assessment of aeroengine performance. Conventional mass-flux measurements are facilitated with invasive temperature and pressure probes which tend to disturb the flow, generate shock structures, have limited lifetimes, and require frequent maintenance. In response, there is a growing opportunity for tunable diode laser (TDL) diagnostics, which can be deployed noninvasively with fast time response and high accuracy. The focus of this work is the development of a TDL mass-flux sensor based on water vapor absorption for deployment in a combustion-driven Mach 2.7 wind tunnel at NASA Langley. The 1f-normalized wavelength-modulation spectroscopy with second harmonic detection (WMS-2f/1f) technique was employed for its unique noise-rejection capability and increase in signal-to-noise ratio; this method was used to measure velocity with improved precision while simultaneously determining temperature. Density was inferred from an independent pressure measurement and the ideal gas law. The sensor temperature measurements were validated against thermocouple readings in a heated cell at Stanford to within 1%. Measurements of velocity were made in a low-speed wind tunnel with accuracy within 0.5m/s of a pitot probe reading; a reduction of 50% in the standard deviation of the velocity measurement was also observed by using optimized WMS-2f/1f. In addition, the influence of flow nonuniformity on line-of-sight (LOS) measurements is investigated by simulating path-integrated lineshapes from computational fluid dynamics (CFD) solutions. The results are quantified in order to develop a correction to the path-integrated measurements obtained in this work. The capstone mass-flux measurements were performed in the NASA Langley Direct-Connect Supersonic Combustion Test Facility isolator. Temporally resolved velocity data was corrected according to the nonuniformity analysis of path-integrated lineshapes, bringing the sensor velocity measurement within 0.25% of the value predicted by the facility code (4m/s in a 1630m/s flow). Temperature measurements were made with high precision (10K standard deviation in a 990K flow), and agreement with the predicted value was also within 1%. Mass-flux measurements had similar precision (standard deviation less than 1% of full scale) and accuracy (within 1% of predicted value). Finally, spatially resolved velocity and mass-flux data taken along both the height and width of the isolator were found to be in close agreement with the CFD solution. These results show that TDL mass-flux sensing based on WMS-2f/1f can produce temporally and spatially resolved measurements with high precision and accuracy in a supersonic flow, thus demonstrating the sensor's potential for future deployment in unknown mass-capture environments such as inlet models and flight tests.
The development of high-temperature stable amorphous metal alloy gates for the reduction of threshold voltage variability in short channel CMOS devices [electronic resource]
Keywords: Materials Science and Engineering

Polycrystalline metal gates have replaced polycrystalline silicon gates in complementary metal oxide semiconductor (CMOS) devices for high speed performance applications. This is because the decreased capacitance caused by the gate electrode depletion layer in polycrystalline silicon gates was a pressing concern for device performance and continued scaling. Metal gates do not have this depletion issue; however, work function tuning is an issue. Consequently, a focus in the metal gate area is placed on work function engineering and the effect of processing conditions on the effective work function. The first project in this thesis studies the effect oxygen on the work function of tungsten electrodes. It is found that the presence of the meta-stable A15 phase is correlated with oxygen concentration. It is hypothesized that the observed variation in work function is due to the incorporation of oxygen from the growth environment into the W layer at the SiO2/W interface. This work shows that stochastic fluctuations in processing conditions could also cause wafer-to-wafer variability, even in long channel devices. Another concern with metal gates is that due to their polycrystalline nature, device variability could become a problem as the gate dimensions are scaled down and become comparable to the grain size since work function can vary significantly with varying grain orientation. The main project in this thesis is to develop amorphous metal gates that have the potential to reduce work function variability with respect to polycrystalline gates in nano-scale MOS devices. Thus, high temperature stable amorphous Ta40W40Si10C10 gates were developed and it is also shown that when Ta40W40Si10C10 gate electrodes are integrated in long channel transistor devices, the effective channel mobility appears to be enhanced with respect to crystalline gates.
The development of miniaturized microscopes for in vivo neuronal imaging in freely moving mice [electronic resource]
Keywords: Mechanical Engineering

A central goal in neuroscience is to explain animal behavior in terms of causal cellular processes. It has been a longstanding challenge, however, to simultaneously track behavior and the cellular dynamics driving it. In this thesis, I discuss how a series of one- and two-photon fluorescence microscopes, based on gradient refractive index (GRIN) lenses, were developed to meet this challenge. The predominant difficulty in the design of these microscopes was how to take a traditional bench top microscope and shrink it to a size small enough for a mouse to easily carry on its head, a limit of 3 grams. We chose mice as our design target due to the wide availability of genetically modified mouse models for the study of cognitive functions, animal behaviors, and disorders of the nervous system. The earlier devices, relying on fiber optics to bring light to and from the animal, met with limited success but still provided useful insight in the development of the surgical techniques and analytical tools necessary for later successful experiments. In contrast, our latest system fully integrates the entire light pathway onto the head of mouse, eliminating many of the remaining roadblocks to truly freely-moving imaging. This device has enabled novel observations of both microcirculatory and neuronal calcium dynamics in the cerebellum of freely-moving mice at frame rates up to 100 Hz. As the genetic toolbox for mice continues to mature, these miniaturized microscopes will facilitate a wide set of future studies of how cellular function in the brain varies across different behavioral and physiological states.
Development of stable metal oxide electrodes for the conversion of electricity to chemical fuels [electronic resource]
Keywords: Chemistry

The conversion of renewable sources of electricity to molecular fuels is widely viewed as an important component of our future energy economy. To accomplish this, stable electrodes are necessary to perform electrochemical reactions of interest for extended periods of operation with high efficiency. In the first part of this thesis, a method to immobilize homogeneous catalysts to a metal oxide electrode through click chemistry on an attached p-azidophenyl phosphonic acid linker is presented. This strategy allows for a convergent approach to surface modification that results in stable attachments while allowing for facile charge transfer between the electrode and the immobilized catalyst. The deposition of p-azidophenyl phosphonic acid to the metal oxide surface and subsequent click with molecules of interest was investigated with Fourier transform infrared spectroscopy, electrochemistry and X-ray photoelectron spectroscopy. The electrochemical oxidation of water to supply the electrons need for fuel synthesis remains a challenge due to the lack of materials which can both efficiently remove four electrons and withstand the harsh oxidative conditions of the reaction. A novel type of dimensionally stable anode utilizing silicon as the base substrate and also as an in-situ photon collector has been developed. It uses a thin amount of titanium dioxide as a protective layer deposited by atomic layer deposition. A thin layer of physical vapor deposited iridium is used as the water oxidation catalyst. Results shown include water oxidation efficiency in both light and dark conditions and over a range of pH values with an emphasis on the operational stability and durability of the anodes.
Development of techniques for live cell RNA imaging [electronic resource]
Keywords: Chemistry

The development of live cell RNA imaging techniques will lead to the unraveling of many important biological processes. To achieve this goal, there have been three different strategies developed. They are the development of small molecule probes, nucleic acid probes, and green fluorescent protein (GFP) probes. In the following thesis, the pros and cons of each approach are discussed, followed by a proposal to resolve the limitations. In the small molecule case, a probe was developed that utilized a quenched sulforhodamine dye. It was designed so that its structure can be rationally modified from the initial lead compound. An aptamer sequence that activates the sulforhodamine probe with micro molar affinity was found by in vitro Systematic Evolution of Ligands by Exponential Enrichment (SELEX), followed by fluorescence screening in E.coli. The rational modification of the structure of the initial sulforhodamine probe resulted in an overall 33-fold increase in binding affinity compared to the initial lead compound. Instead of the chemical modification of the lead compound, the small molecule's cell permeability and binding affinity to the target could be improved by linking to cell penetrating peptides (CPP). A CPP is a short peptide sequence composed of poly arginine amino acids which shows excellent cell uptake and affinity to RNA. However, the use of the CPP-linked dye in live cell imaging has been limited by strong signals in the endosome region. An attempt was made to overcome this difficulty by linking a quencher molecule to the dye-CPP via a disulfide bond, which only breaks when it enters the cytosol. For the nucleic acid probe, the major problem was its low cell permeability and low signal-to-background ratio due to the low copy number of mRNA targets within the cell. We made mutant Hammerhead ribozymes and embedded them in a non-coding region of the GFP expression vector that can be transfected to mammalian cells. This modified Hammerhead ribozyme acts as a logic gate, and the signal is amplified by the expression of GFP in the presence of the target mRNA. In vitro and in vivo results are discussed. Finally, a fragmented GFP system, the fluorescence of which could be recovered by binding to a specific RNA tag, was developed. The major problem for the GFP-mediated RNA imaging system was the low signal-to-background ratio from the GFP probe that is not bound to the RNA tag. To find the non-fluorescent GFP, the GFP was truncated from the C-terminus such that it loses its fluorescence with minimum loss of amino acids. An RNA sequence that has high affinity to this GFP was found by in vitro SELEX. The subsequent E.coli screening found an RNA sequence that reactivates the fluorescence of the GFP probe.
The development of techniques for three-dimensional super-resolution fluorescence microscopy and their application to biological systems [electronic resource]
Keywords: Chemistry

Fluorescence microscopy is one of the most widely used tools in cell biology due its intrinsically high detection sensitivity coupled with the ability to genetically label proteins and other cellular structures with fluorescent tags. However, the resolution of fluorescence microscopy has historically been limited to about 200 nm laterally and 800 nm axially because of the diffraction limit of visible light. In the past five years, imaging below the diffraction limit ("super-resolution imaging") by localizing single fluorophores, one at a time (1-3), has opened a wide a variety of new biological systems for study. This Dissertation is a collection of both techniques for two and three dimensional super-resolution imaging as well as applications in bacterial and yeast imaging. References 1. Betzig E, et al (2006) Imaging intracellular fluorescent proteins at nanometer resolution. Science 313: 1642-1645. 2. Hess ST, Girirajan TPK & Mason MD (2006) Ultra-high resolution imaging by fluorescence photoactivation localization microscopy. Biophys J 91: 4258-4272. 3. Rust MJ, Bates M & Zhuang X (2006) Sub-diffraction-limit imaging by stochastic optical reconstruction microscopy (STORM). Nat Methods 3: 793-795.
Device technology for nanoscale III-V compound semiconductor field effect transistors [electronic resource]
Keywords: Electrical Engineering

As silicon CMOS technology reaches its fundamental scaling limits, alternative materials such as high mobility III-V compounds have proven to be strong contenders for extending high performance logic. However, most promising demonstrations of III-V FET/HEMTs have micron-scale source/drain spacing despite gate lengths on the nanometer scale. III-V semiconductor devices have historically relied on alloyed ohmic contacts which require large spacings to prevent shorting between the source and drain after alloying, where contacts can diffuse up to hundreds of nanometers. This severely limits the scalability of III-V logic technology. Non-alloyed contacts offer a practical route to greatly reduce the III-V device footprint for application in future technology nodes. In this dissertation, I demonstrate a route to non-alloyed contacts by shifting the pinned III-V Fermi level to reduce the metal/n-GaAs and metal/n-InGaAs Schottky barrier heights. The Fermi level is controlled by the insertion of thin dielectrics in a metal-insulator-semiconductor (MIS) contact structure. The MIS contact is studied across a wide range of metal and dielectric materials, and found to have great flexibility in the material selection. I will also discuss the use of bi-layer high-[kappa] dielectrics, and report results which show that despite an overall thicker dielectric, there is an additional reduction in the barrier height and contact resistance beyond that of a single dielectric MIS. This MIS contact is then integrated in an InGaAs MOSFET as a non-alloyed source/drain contact, though it can also be applied to Schottky Barrier FETs. I will conclude by discussing possible physical mechanisms of the observed barrier height reductions, by examining the effects of fixed charge and electronic dipoles.
A diagrammatic kinetic theory for describing long timescale correlations in dense, simple liquids in the overdamped limit [electronic resource]
Keywords: Chemistry

Starting from an exact diagrammatic theory for density correlations in dense, atomic fluids, we derive a set of graphical approximations to this theory that are consistent with a set of physical assumptions that define an overdamped limit of the dynamics of the system. The results of a simple one loop approximation to this theory are then compared with data from molecular dynamics simulations for a number of correlation functions of a simple Lennard-Jones fluid at a single, high density and a range of temperatures. For correlation functions that have most of their decay over times for which the overdamped theory is valid, the one loop approximation gives accurate results, except for coherent correlation functions at small wavevector, for which the overdamped theory is not expected to be accurate. Although the temperature range we studied included only temperatures at or above the liquid's triple point, it is our hope that the overdamped theory can ultimately be used to characterize the dynamics of supercooled liquids. This will certainly require going beyond the one loop approximation.
Directors’ and Officers’ Insurance: Ordinary Corporate Expense or Valuable Signaling Device?
Keywords:  Department of Economics
Stanford Department of Economics
corporate governance
D&amp;O insurance
premium
litigation risk
Thesis

After many years in which directors have used directors’ and officers’ (D&O) coverage to shield themselves from personal responsibility for corporate failure, directors at Enron and WorldCom have been forced to pay $31 million out of their own pockets to settle securities class action lawsuits stemming from two of the largest corporate governance scandals in U.S. history. These settlements have brought the question of director's liability to the foreground, generating interest in the extent to which a firm’s D&O liability coverage reveals valuable information regarding its quality of corporate governance. Since insurers are expected to perform a thorough examination of the directors for whom insurance protection is sought, there is reason to believe that poor governance increases litigation risk and thus the size of the insurance premium. Using a sample of D&O premiums gathered from the proxy statements of firms cross-listed in the U.S. and Canada, I find a significant negative relationship between D&O premiums and variables that proxy for the quality of firms’ governance structures. This association is robust to a number of alternate specifications. As further evidence that the D&O premium reflects the quality of a firm’s corporate governance, the proxies for weak governance are positively related to excess CEO compensation. Overall, these results suggest that the D&O premium can be a useful measure of the quality of a firm’s governance.
Discovery and synthesis of novel chloride transport protein inhibitors [electronic resource]
Keywords: Chemistry

CLC chloride channels and transporters play diverse physiological roles in processes ranging from regulating bone-density, muscle excitability, and blood pressure, to facilitating extreme-acid survival of pathogenic bacteria. Defects in CLC proteins cause human disorders in these processes. Small-molecule inhibitors of the CLCs would be useful as drugs for treating a variety of CLC-related human diseases and also to investigate CLC physiology. In addition, inhibitors are powerful tools for studying molecular mechanisms of Cl-- gating. Trapping channels or transporters in particular conformational states with high-affinity ligands could potentially advance our understanding of the structural basis for CLC activity. Despite their usefulness, specific small-molecule inhibitors for CLC proteins are scarce. To address this shortfall, we have exploited the 4,4'-diisothiocyanatostilbene-2,2'-disulfonic acid (DIDS) scaffold to develop two novel classes of CLC inhibitors. DIDS has been used as an anion-transport inhibitor for decades and was first used to inhibit CLCs over 30 years ago. However, experiments to determine the compound's mode of inhibition led us to discover that minor contaminants in the DIDS solutions inhibit CLC proteins more effectively than DIDS itself. The contaminants were found to derive from hydrolysis of the labile isothiocyanate moieties. The structures of five major hydrolysis products were determined by 1H NMR, HRMS analysis, and chemical synthesis to be DIDS-based polythioureas. These compounds bind directly to the CLC proteins, as evidenced by the fact that they inhibit purified, reconstituted ClC-ec1 and that inhibition of ClC-Ka can be prevented by the point mutation N68D. These polythioureas are the highest affinity inhibitors known for the CLCs and provide a new class of chemical probes for dissecting the molecular mechanisms of chloride transport. The second class of identified CLC inhibitors combines the DIDS core structure with alkyl chain carboxylic acids. The most potent inhibitor identified, 4,4'-octanamidostilbene-2,2'-disulfonic acid (OADS), inhibits ClC-ec1 with an apparent affinity of 29 [Mu]M. As a means to identify the inhibitor-binding site, we synthesized photo-reactive diazirine derivatives of OADS and showed that these photo-affinity reagents specifically inhibit ClC-ec1. Experiments to identify the binding site using 'top-down' mass spectrometry, in which the protein is cleaved into peptide fragments via electron-capture dissociation, have identified an intracellular binding region encompassing 76 amino acids, or 16% of the protein. Current efforts using protease digestion procedures are focused on further refinement of the binding region. Once located, protein/inhibitor interactions gleaned from the labeling of ClC-ec1 could allow us to rationally design more potent inhibitors of CLC transporters and channels.
Discovery of the two-neutrino double-beta decay of xenon-136 with EXO-200 [electronic resource]
Keywords: Physics

Recent neutrino oscillation measurements provide definitive evidence for non-zero neutrino masses. Oscillation measurements, however, only measure mass differences, not the absolute mass scale. Neutrinoless double-beta decay, a hypothetical nuclear transition, can probe the absolute neutrino mass scale. This process, if observed, would also imply that neutrinos are their own anti-particles and that lepton number is not a conserved quantity. The 200 kg Enriched Xenon Observatory (EXO-200) detector is currently taking data to search for the neutrinoless double-beta decay of Xe-136, with an expected half-life in excess of 10^25 years. Located at the Waste Isolation Pilot Plant (WIPP) near Carlsbad, New Mexico, the detector is filled with 200 kg of isotopically enriched liquid xenon. The analysis presented here describes the recent observation with EXO-200 of the two-neutrino double beta-decay of Xe-136. This is the rarest process ever directly observed with a half-life of 2.11+-0.21 x 10^21 years and provides important input to the measurement of the neutrinoless decay.