VictorJuiz/thesis huggingface dataset:
A study on the feasibility of lunar farside radio observations using a small satellite based telescope [electronic resource]
Keywords: Aeronautics and Astronautics

Radio astronomers have been able to observe extensively from 300 GHz to 100 MHz in the last sixty years, however observations at lower frequencies are sparse, mainly due to Earth-based interference and noise. There are intriguing scientific questions that have the potential to be answered by observing at these long wavelengths, especially in the field of cosmology, although solar physics, planetary studies, black hole physics, and the possibility of new discoveries are also exciting areas. This thesis looks at radio telescopes currently observing and proposed, and suggests that a lunar orbiting telescope mounted on a small satellite (such as a cubesat) could be a cost effective approach to answering some of these open questions. The specific goal of this study is to determine an orbit that would enable a small satellite to complete such a mission. Starting with analytical models developed in the literature that predict quasi-stable or 'frozen' orbits, high fidelity numerical simulations are run that narrow the orbital parameters to determine a satisfactory solution. The results show that a near circular, 28.5° inclination orbit at 150 km is stable enough over at least two, and up to five years in orbit, giving at least 6400 hours of quiet sky observation time. Finally, studies are performed to determine how accurate orbital insertion must be to meet requirements.
Studying zebrafish development and regeneration with chemical probes [electronic resource]
Keywords: Chemical and Systems Biology.

Embryonic development and tissue regeneration are regulated by complex genetic programs that are dynamically executed in a stereotypic manner, and deciphering these molecular mechanisms requires the ability to control gene function with spatial and temporal precision. Synthetic chemistry has been increasingly used to create reagents that can enable such genetic manipulations. In this thesis I describe the development and application of caged morpholino (cMO) oligonucleotides and small molecules to study zebrafish embryonic development and larvae tail regeneration. In Chapter 1, we survey how chemical tools and engineered proteins have been used to perturb developmental processes at the DNA, RNA, protein, and cellular levels. We discuss the design principles, experimental capabilities, and limitations of each method, as well as future challenges for the chemical and developmental biology communities. In Chapter 2, we describe optimized methods for the design and synthesis of hairpin cMO oligonucleotides incorporating a dimethoxynitrobenzyl (DMNB)-based bifunctional linker that permits cMO assembly in only three steps from commercially available reagents. Using this simplified procedure, we have systematically prepared cMOs with differing structural configurations and investigated how the in vitro thermodynamic properties of these reagents correlate with their in vivo activities. Through these studies, we have established general principles for cMO design and successfully applied them to several developmental genes. Our optimized synthetic and design methodologies have also enabled us to prepare a next-generation cMO that contains a bromohydroxyquinoline (BHQ)-based linker for two-photon uncaging. Collectively, these advances establish the generality of cMO technologies and will facilitate the application of these chemical probes in vivo for functional genomic studies. In Chapter 3, I first describe our genome-wide microarray analysis and whole-mount in situ hybridization studies that led us to the identification of 18 genes, including hyaluronan synthase 3 (has3), that were expressed during zebrafish larvae tail regeneration. I also report the functional studies of hyaluronan (HA) synthesis using small molecule inhibitor 4-methylumbelliferone (4-MU), in which we showed that 4-MU inhibited tail regeneration by preventing injury-induced cell proliferation. In addition, 4-MU also reduced the expressions of dlx5a and junbb, markers of the wound epithelium and blastema-like mesenchymal cells. We also illustrated that simultaneous dosing of Gsk3[beta] inhibitor BIO and 4-MU could rescue the 4-MU-induced regeneration defects. Our results indicated that the crosstalk between hyaluronan synthesis and Gsk3[beta] signaling played an important role in regulating tail regeneration.
Sub-harmonic generation of frequency combs for spectroscopy and quantum optics [electronic resource]
Keywords: Electrical Engineering

Extensive development of optical frequency combs, broadband coherent light sources with equidistant narrow spectral lines, in the near-infrared and visible has provided numerous opportunities in many fields, including frequency metrology, astronomy, attosecond sciences, and spectroscopy. The quest for extension of frequency comb techniques to the mid-infrared -- the molecular fingerprint spectral region -- continues with the promise of significant improvements in various applications related to molecular spectroscopy. This dissertation presents the results of a novel method for producing broadband mid-infrared frequency combs through sub-harmonic generation from commercially available near-infrared sources. Sub-harmonic generation occurs in a degenerate optical parametric oscillator (OPO) with salient features of (i) simplicity of the setup, (ii) low (< 100 mW) pump power requirement, (iii) potential for high (> 90%) conversion eciency and (vi) intrinsic phase and frequency locking to the pump. The resulting mid-infrared frequency comb is then broadened through supercontinuum generation by in-situ tapering of a chalcogenide fiber to cover the spectral range from 2.2 to 5 microns, desirable for molecular spectroscopy. Apart from its effectiveness in extension of the existing near-infrared frequency combs to the mid-infrared, sub-harmonic generation paves the way for quantum optical experiments in the frequency comb regime, because of the intriguing quantum behavior of OPOs at degeneracy. The coherence properties of such a frequency comb OPO are discussed, and the results of a novel all-optical post-precessing-free quantum random number generator are presented.
Superconductivity in reduced dimensions [electronic resource]
Keywords: Physics

This thesis covers three different superconducting systems. One dimensional aluminum rings, and two dimensional heterostructures of LaAlO3/SrTiO3 and ß-doped SrTiO3. In all cases we studied the magnetic response of these superconductors using a scanning SQUID microscope. In our study on 1D aluminum rings, we monitor the magnetic response of the persistent supercurrent to explore the impact of phase fluctuations on the ring's ability to screen magnetic fields. The physical parameters of the rings were designed to reduce the superconducting phase stiffness. We observe a suppression of the susceptibility signal below the critical temperature, which we attribute to a thermodynamic sampling of metastable states with different phase winding number, termed fluxoid fluctuations. We find our data is well descried by a simple theoretic model wich accounts for a thermodynamic sampling of fluxoid states. The next part of the thesis discusses two dimensional superconductors at the interface of complex sides. In LaAlO3/SrTiO3, we discovered nanoscale patches of magnetism coexisting with inhomogeneous superconductivity. We analyze the magnetic field from the magnetic patches and find it is not large enough to be responsible for the inhomogeneity observed in the superconductivity. Instead, we found that a landscape of isolated paramagnetic spins is the driving source of the inhomogeneity. The gate tunable nature of the LAO/STO interface provides an additional avenue for studying the superconductivity. Our measurements of the temperature dependence of the superfluid density, taken at different gate voltages, collapse to a single curve characteristic of a full superconducting gap. This indicates that superconductivity in this exotic system may be conventional in nature. Finally, we measured the temperature dependence of the superfluid density of ß-doped STO using two different techniques and show that it is also a conventional superconductor.
Supersymmetries in the early universe [electronic resource]
Keywords: Physics

This thesis studies the role of supersymmetry in early universe physics, with emphasis on dark matter phenomenology and cosmic inflation. Motivated by observational anomalies, the first half of the thesis proposes a new class of dark matter: composite nearly supersymmetric dark matter. To establish the constraints imposed by supersymmetry on non-relativistic bound states, a supersymmetric version of the hydrogen atom is studied in detail, and general features are emphasized. After discussing supersymmetry breaking and the interactions of supersymmetric bound states, a dark matter model, where interactions with the Standard Model communicate supersymmetry breaking, is developed. The second part of the thesis develops a class of single field inflation models within the framework of supergravity, which allows for functional freedom in choosing the shape of the potential. A relationship between inflaton stability and the Kähler potential is established. This model is then extended to include the matter fields of the visible sector, and supersymmetry breaking is induced using a phenomenological version of the KKLT model. Finally, reheating, and a solution of the cosmological moduli and graviton problem, are discussed.
Surface cleaning technology using non-newtonian fluids [electronic resource]
Keywords: Chemical Engineering

This dissertation explores the performance of a new particle removal technology using polymer solutions and jet flow. One effective approach involves the use of a water jet falling vertically on the substrate coated with a layer of the viscoelastic polymer solution, called the "rinsing flow." This work aimed to understand this particle removal process at both the macroscopic and the molecular levels. Experimental efforts were made to observe the effect of fluid rheology on the transient rinsing flow pro file. Then, factors that influence particle removal of a silica-glass model system were explored. The molecular interaction between the polymer coils and the model particle surface was also investigated. The combined results of these experiments revealed that the overall procedure achieved particle removal through a multi-stage process. Adhesion was decreased due to both the reduction of van der Waals interaction in liquid media as well as polymer adsorption onto the particles. Then, the high extensional viscosity of the polymer solution, coupled with the extensional flow component of the jet flow, were found to be the dominating factors in providing the hydrodynamic force to overcome the remaining adhesion and achieve particle detachment.
Synthetic studies on the potent voltage-gated sodium ion channel agonist batrachotoxin [electronic resource]
Keywords: Chemistry

Batrachotoxin (BTX) is a complex steroidal alkaloid that causes depolarization and persistent activation of voltage-gated sodium ion channels (Nav). These channels are large transmembrane proteins that are responsible for the rapid transmission of electrical impulses in neuronal cells. Much remains unknown about the structure and function of these integral proteins as well as the origins of the complex array of responses that batrachotoxin elicits when applied to Navs. Structure-function analysis has been limited due to the paucity of the natural product, whose primary source is endangered Colombian poison dart frogs, and the small number of available congeners and semi-synthetic analogues. Synthetic efforts were undertaken to construct batrachotoxin in a modular, convergent fashion that would facilitate access to both the natural product and analogs thereof. Construction of the C/D/E ring system was first targeted based on pharmacological data indicating that variations in this portion of the molecule dramatically reduced activity. A synthetic plan was successfully executed that capitalized on the latent symmetry of the D ring in order to maximize convergency. Key steps include a novel Mannich reaction, intramolecular C-ring closure from an unusual bis-acetal, and formation of the unique homomorpholine ring structure through intramolecular reductive amination or SN2 displacement. A furan moiety was purposefully introduced as a B-ring surrogate for use in subsequent Diels-Alder reactions with the goal of generating both BTX and novel A/B-ring analogs. Intermolecular benzyne-furan Diels-Alder reactions provided access to the pentacyclic ring system of BTX. When efforts to introduce the C19 angular methyl group through dearomatization processes proved unfruitful, a revised synthetic strategy was explored. Cyclohexallene, cyclohexyne, and cyclopropene dienophiles were found to undergo furan Diels-Alder reactions to furnish steroidal core structures. Together with the successful use of benzyne, these results demonstrate that highly-strained dienophiles can serve effectively in intermolecular Diels-Alder reactions with structurally advanced diene derivatives. Through these studies, CsF was found to be a uniquely effective promoter for in situ generation of strained dienophiles, which reacted in most cases to give high yields of the desired cycloadducts. Strategies outlined in this thesis toward the synthesis of batrachotoxin lay the foundation for the construction of both the natural product and other highly oxidized steroidal compounds. De novo chemical synthesis has enabled preparation of C/D/E ring BTX analogs, unique molecular probes that are now being used to elucidate the structure of the batrachotoxin binding site in voltage-gated sodium ion channels and to explore the remarkable effect of this natural product on channel function.
Targeting latent HIV [electronic resource] : the design, synthesis and evaluation of prostratin analogs
Keywords: Chemistry

The theme of this work is to utilize hypothesis driven synthetic manipulation to enhance our understanding of the biological effects of prostratin and its highly potent analogs, and to utilize this understanding for the improvement of the therapeutic properties thereof. Prostratin, a natural product activator of protein kinase C (PKC), is a molecule of interest for targeting latent HIV, the primary obstacle to HIV eradication in infected individuals on effective highly active antiretroviral therapy. Chapter one describes the current state of the HIV pandemic, therapeutic strategies, prospects for a cure, and clinical studies toward immune activation therapy. Chapter two is a seminal and complete analysis of the biological effects of prostratin, a natural product candidate for immune activation therapy. Chapter three presents the design, synthesis, and evaluation of highly potent analogs of prostratin via an efficient semi-synthetic route. Chapter four presents the design and synthesis of isotopically labeled prostratin analogs to be utilized in solid-state NMR studies probing the active conformation of the PKC/activator complex in its membrane associated state. Chapter five presents the design, synthesis, and evaluation of prodrugs of prostratin and prostratin analogs for the optimization of pharmacologic properties.
Taxation, natural resources, and representation [electronic resource]
Keywords: Political Science.

The thesis re-examines the links between the sources of government funding, representation, and accountability and analyzes whether and how the sources of a government's revenues are connected to the behavior of its political actors. Evidence is drawn from instances in which both sub-national and national governments experience large, exogenous changes in the origins of their funding due to the discovery or assignment of resource revenues. Contrary to claims in the existing literature that institutions are the result of resource abundance, the thesis proposes to view the quality of pre-existing institutions as the origin of natural resource dependence. Natural resource abundance translates into natural resource dependence only in the presence of poor institutions. In an empirical analysis using a panel of 98 oil- producing countries from 1918-2004, there is no evidence for the impact of crude oil production on the quality of political institutions. In a subnational analysis of Brazilian municipalities, the thesis provides evidence that access to non-tax resources allows governments to choose inefficient spending patterns and be less concerned about the well-being of its constituents. However, electoral accountability remains an accountability tool, though weakened, to mediate these negative effects, particularly by informed voters. In general, the effects of non-tax revenues such as resource income are found not to be uniform. Instead, they differ with the circumstances, including economic development, institutional environment, and geography.
Têtes de Turcs [electronic resource] : une étude comparée des représentations des grands seigneurs et des Turcs dans la France de L'Ancien Régime
Keywords: French & Italian.

The figure of "the Turk" entered the French literary scene in the sixteenth century but its presence increased from the early years of Louis XIV's reign. Thanks to a multiplication of trading contracts, political alliances, and diplomatic missions to Constantinople, citizens of the Ottoman Empire took rapid hold of the French imagination. It is commonly thought, especially in the wake of Edward Saïd's work, that this imagination had a vested interest in portraying "the Turk" as inferior, weak, and irrational. In fact, however, literary representations of Ottoman Turks in seventeenth century took a very different tack, presenting them in a manner almost identical to representations of a figure that was itself becoming increasingly exotic in the seventeenth century: that of the warrior noble/ Feudal lord. "The Turk" was in fact no more cruel, passionate or generous than the warrior noble; the warrior noble was no more fierce, strong, or heroic than "the Turk." In this dissertation we intend to demonstrate this connection, thus raising a crucial objection to Saïd's thesis, and also to investigate the reasons for the striking correlation in modes of representation for two human types we might expect to have been considered antithetical.
That is only a mirror..., a musical composition exploring the question of what constitutes identity in an environment saturated by reflected musical materials [electronic resource]
Keywords: Music

This dissertation is comprised of the musical composition "That Is Only A Mirror..." as well as this introductory paper that goes into a brief account of its thematic ideas and their compositional use. "That Is Only A Mirror..." is approximately 10 minutes in duration. It was composed for the New York-based new music group the Talea Ensemble and is scored for flute, oboe, Bb clarinet, Bb trumpet, trombone, percussion, piano, violin, viola, and cello. The piece is explores the question of what constitutes identity by inviting the comparison of nearly indistinguishable yet continually varied and recontextualized musical materials. Comparison and contextualization of simultaneous, sequential, and delayed placements of variously derived musical sound objects (i.e. musical materials) in time is the primary means of exploring this issue in the piece.
The Build America Bonds Program: Savings Opportunities and Efficiency Improvements from Subsidizing Taxable Municipal Debt
Keywords:  Department of Economics
Stanford Department of Economics
American Recovery and Reinvestment Act
Build America Bonds
BABs
Municipal Finance
Public Finance
Direct Subsidy
Stimulus Plan
Thesis

As a result of the 2008-2010 financial crisis, municipal borrowers (state and local governments, school districts, transit agencies, water utilities, etc.) faced increased borrowing costs and a risk-averse investor base that made it difficult to finance continued public spending, let alone fiscal stimulus. The Build America Bonds program was touted as a means to ease the credit crunch faced by municipal issuers through Federal interest subsidies on taxable municipal debt, providing an additional borrowing instrument alongside traditional tax-exempt municipal bonds. By allowing municipal borrowers subsidized access to taxable debt markets, the program was designed to lower borrowing costs, and draw new groups of investors (such as pension funds and 401(k) accounts) to municipal bonds that would not be attracted by the tax exemption structures of traditional municipal debt. This paper finds that the program met its objectives of lowering borrowing costs, as seen by an average yield savings of 69 basis points versus issuing in the tax exempt market, and attracting non-traditional investors, as indicated by low marginal tax rates for BAB investors. This paper argues that the Build America Bonds program was a success, and worthy of extension as a long-term alternative to tax exemption, although the subsidy proposed in President Obama’s 2013 Budget is overgenerous.
The effect of in-situ ocean acidification on the community structure of marine invertebrates with a focus on the gastropod Columbella rustica
Keywords: Stanford Biology Department
Ischia Island Italy
Castello Aragonese
ocean acidification
Columbella rustica.
Thesis

Laboratory experiments show that ocean acidification can be detrimental to the growth and calcification of many organisms at the species level. However, the effects of ocean acidification at the ecosystem-scale are less studied and harder to predict due to the diversity of responses of taxa. Areas with naturally high CO2 levels are becoming increasingly important in determining community level responses of ecosystems to ocean acidification. This study adds to previous work conducted along a natural acidification gradient caused by cool volcanic vents in Ischia, Italy. Researchers found an increase in tolerant crustacean taxa but were unable to separate this increase from habitat-dependent causes. To eliminate this confounding variable, benthic invertebrate communities were characterized using artificial substrate to standardize the habitat. The primary objective, to examine the processes underlying community reorganization of mobile invertebrates caused by ocean acidification, was achieved by sorting 18 samples collected along the gradient to the lowest taxonomic level possible. To assess the physiological consequences of acidification for the dominant gastropod species, the characteristics of the dominant gastropod in the system, Columbella rustica, were surveyed for differences in size, shell condition and shell and body weight between the ambient and low pH zones.
Our results highlight the differing responses of invertebrate taxa to ocean acidification, showing a general decrease in calcifying organisms at lower pH and an increase in those taxa that exhibit little to no calcification. When the habitat was held constant, the increasing abundance of crustacean taxa seen in previous studies at these vents (when the habitat varied with the pH) was not observed. These results suggest that the increased abundance of small crustacean grazers at extreme low pH reported in a previous study is likely associated with changes in the structural characteristics of the habitat and cannot be attributed to a direct benefit of low pH to these taxa. Preliminary results also indicate that calcifying gastropods can cope with increased acidity, but at a pH threshold, the snails lose their ability to cope with increasing acidity through adaptive mechanisms.