VictorJuiz/thesis huggingface dataset:
Constraints on a 2D CFT Dual to Weakly Curved AdS Gravity

An extremal CFT is a CFT whose spectrum matches that of pure gravity through the AdS/CFT correspondence. We examine the constraints imposed on the elliptic genus of an N = 2 extremal CFT for half odd integer values of 'm'. The integer case of 'm' has been previously studied. 'm' is a measure of the degrees of freedom of the theory, and it is half integrally quantized. We found that our CFT model with minimum content (i.e. only the vacuum module) did not satisfy the appropriate form requirements for an extremal polar polynomial. Thus, we conclude that we must add a minimal number of particle states to the bulk such that a ‘near extremal’ dual CFT exists.

Keywords:  Department of Physics
conformal field theory
AdS/CFT correspondence
elliptic genus
modular invariance
pure supergravity
Thesis
Advisor: Kachru Shamit
Hartnoll Sean
Constraints on subglacial conditions from mechanical models of ice stream processes [electronic resource]

Motivated by the hazard associated with Antarctica's contribution to sea level rise, we examine localized regions of fast flowing ice called ice streams. We explore several recent observations from the Antarctic Ice Sheet with the goal of constraining subglacial conditions and improving our mechanical understanding of these systems. Our strategy generally consists of comparing the predictions of simplified mechanical models with geophysical data. We first examine seismic signals arising from the resonant vibrations of water-filled subglacial and englacial fractures, as well as fractures in other geological systems. We then shift attention to the Whillans Ice Plain (WIP) sector of the West Antarctica Ice Sheet (WAIS). The WIP experiences tidally-modulated, twice daily slip events. These slip events bear a striking similarity to subduction zone slow slip events. Slip events are accompanied by seismic tremor, which we additionally use to constrain subglacial conditions. We use the occurrence of ice stream slow slip events and tremor as an opportunity to validate rate- and-state friction as a glacier sliding law. For this reason, this thesis constitutes a step towards a more detailed description of the strength of the ice-bed interface.

Keywords: Geophysics.
Advisor: Dunham Eric primary advisor. Thesis advisor
Beroza Gregory C. (Gregory Christian) advisor. Thesis advisor
Segall Paul
Suckale Jenny advisor. Thesis advisor
Consumers, interrupted [electronic resource] : the effect of interruptions on persuasion and decision making

Individuals experience a greater frequency of interruptions than ever before. In the current research, I find that interruptions provide opportunities for subjective cognitive experiences (e.g., curiosity, need for closure) to enter consumers' thought processes and shape their attitudes and decisions about products not only within the interrupted domain (Chapter 1) but also outside of it (Chapter 2). Chapter 1 reveals that interruptions that temporarily disrupt a persuasive message can increase consumers' processing of that message. As a result, consumers can be more persuaded by interrupted messages than they would be by the exact same messages delivered uninterrupted. In documenting this effect, the current research departs from past research illuminating the negative effects of interruptions, and delineates the mechanism through which and conditions under which momentary interruptions can promote persuasion. When consumers are prevented from returning to the interrupted information, Chapter 2 reveals that their unsatisfied desire to view the interrupted information manifests as a need for closure that reduces their processing of unrelated content. Together, this research illuminates the powerful impact that interruptions can have on consumer persuasion and decision-making.

Keywords: Business.
Advisor: Shiv Baba
Tormala Zakary L. primary advisor. Thesis advisor
Laurin Kristin
Contribution of halides to photochemical reactions in estuaries and coastal waters [electronic resource]

Photochemical reactions may serve to mediate natural processes and contaminant degradation in estuaries and oceans. While research into aquatic photochemistry has focused on freshwater-relevant pathways, the impact of high halide concentrations in saline waters—the primary characteristic distinguishing seawater from freshwater—on photochemical processes has received little attention. This dissertation characterizes how halides in seawater alter indirect photochemical reactions by (i) enabling the production of seawater-specific reactive intermediates such as halogen radicals and (ii) by impacting photoproduced reactive intermediates common between fresh and saline waters (e.g. excited triplet state dissolved organic matter, hydroxyl radical). This dissertation also discusses the implications of these altered photochemical processes for biogeochemical processes (e.g. the sulfur cycle) and contaminant degradation (e.g. algal toxins) in coastal and estuarine waters.

Keywords: Civil and Environmental Engineering.
Advisor: Mitch William A. primary advisor. Thesis advisor
Boehm Alexandria advisor. Thesis advisor
Luthy Richard G. advisor. Thesis advisor
A contribution to improve facies object modeling of meandering rivers depositional systems [electronic resource]

This work focuses on improving meandering river architecture in object-based modeling. Object-based modeling is used through the industry to replicate several depositional environments using defined geometries that intend to mimic reality. Meandering river environments, due to their specific and relatively well defined geobodies, are amongst the most represented by object modeling algorithms. Modeling of these systems is mostly controlled by the amount and distribution of its different constituent structures. Channel and levees facies are the main landforms characterized in the literature. These structures are represented by several commercial software often in an over simplistic geometrical form. Furthermore, other bodies pertaining to the meandering river architecture, such as point bars and splays are also not described properly or sometimes not even taken into account at all for modeling purposes. In this thesis, we propose an improved portrayal of meandering rivers not only with the inclusion of these additional landforms (point bars and splays) but by properly investigating and delineating its geometrical configurations and its inter-relation amongst these different arrangements. Application of the above proposed methodology is demonstrated through guided workflows.

Keywords: Energy Resources Engineering.
Advisor: Mukerji Tapan
Control of natural killer cell homeostasis by the aryl hydrocarbon receptor [electronic resource]

Natural killer (NK) cells are lymphocytes that recognize and eliminate infected or abnormal cells. Previously thought of as innate immune cells, emerging research has shown the ability of NK cells to have immunologic memory and mediate an enhanced response upon secondary exposure under certain conditions. This ability is heterogenous, with only subsets of NK cells having memory-like features. A liver resident population of NK cells, defined as CD49a+TRAIL+CXCR6+DX5-, has been found to have antigen-specific memory to hapten exposure. Little is known about the transcription factor regulation that differentiates these liver resident memory NK cells from their conventional counterparts. The aryl hydrocarbon receptor (AhR) was recently found to be uniquely expressed in this subset, and for this project, we sought to explore the importance of AhR in the biology of liver resident NK cells. We found that expression of AhR is required for proper maintenance of liver resident NK cells, and in its absence, hapten-specific memory is lost. Furthermore, we found that AhR is required to prevent over proliferation and exhaustion in response to cytokine activation. Finally, we identified several potential molecular targets of AhR which have homeostatic roles, including the ubiquitin ligase subunit ankyrin repeat and SOCS Box containing 2 (Asb2). Taken together, we show that AhR is important for the proper proliferation and survival of NK cells. The homeostatic role of AhR may be what allows for the long term survival of memory NK cells, and utilization of AhR ligands may provide a way to enhance therapeutic NK cells.

Advisor: Sunwoo John B.
Engleman Edgar G. advisor. Thesis advisor
Krams Sheri Michele advisor. Thesis advisor
Negrin Robert S. advisor. Thesis advisor
Control, performance and safety in programming languages [electronic resource]

Type safety and memory safety are the foundations of most modern programming languages. They assure that a large and important class of bugs simply cannot occur. When type and memory safety are combined with powerful mechanisms to control the functionality of code, such as module systems and monads, abstractions that may have otherwise required modifications to the language can be built. For example security mechanisms for both trusted and untrusted code, such as sandboxes and information flow control mechanisms, can be built and deployed as simple language-level libraries. However, all general purpose programming languages provide features that allow type and memory safety to be violated. For instance, Java has the sun.misc.Unsafe class, Go the unsafe package, and Haskell the System.IO.Unsafe module. These features exist for three reasons. First, they give developers greater control, for example, allowing interoperability with foreign code and hardware. Secondly, developers often use these unsafe features to implement higher performance code than they could otherwise, such as custom memory allocators. Finally, unsafe features are often exposed as an implementation artifact by the language and runtime system implementers, used by trusted parts of the standard library to implement safe abstractions for general consumption. These unsafe features are obviously useful and are widely used by developers, however, they cause three major problems. Firstly, they reintroduce all the possible bugs that type and memory safety remove, Secondly, they break a developer's and static analyzer's ability to reason cleanly about code. Third, they allow language abstractions to be violated, preventing security mechanism being implemented as simple libraries. This thesis explores solutions to the problem of allowing but controlling developer access to unsafe features in programming languages such that code can still be reasoned about and invariants enforced. It looks at it in two parts. First, we describe Safe Haskell, a language mechanism for controlling the use of unsafe features by developers. Secondly, we investigate the use of unsafe features and their use in violating memory safety for performance gains. We describe two novel language mechanisms, M3 and Blade, that open up the memory management subsystem of safe languages without giving up either memory or type safety.

Advisor: Mazières David (David Folkman)
Aiken Alexander advisor. Thesis advisor
Engler Dawson R. advisor. Thesis advisor
Controls on along-strike variations in stratigraphy and provenance of a successor foreland basin system, Jurassic-cretaceous evolution of the southern Patagonian Andes and the Magallanes-Austral Basin [electronic resource]

Sedimentary basins that develop adjacent to convergent plate margins are intrinsically linked to an array of tectonic processes, including those associated with subduction dynamics, crustal shortening, exhumation and topographic uplift, and lithospheric flexure. In turn, each of these processes help to govern the timing and nature in which sediment is transported from mountain belts to ocean basins. Thus, the stratigraphic fill of sedimentary basins is often the best available record for understanding the integrated evolution of convergent plate margins over geologic time scales. However, deciphering that record can be challenging in basin systems with complex histories that include multiple tectonic regimes, tectonic overprinting, and/or incomplete preservation of stratigraphy. This dissertation examines the influences that tectonic inheritance and predecessor basin history can have on the evolution of successor foreland basin systems. While previous workers have demonstrated the temporal influence of tectonic inheritance, this work assesses the spatial relationships by considering along-strike (orogen-parallel) variations in the timing of tectonic events (rifting, collision, basin initiation), stratigraphy and distribution of facies, and source area exhumation and sediment routing. The following four chapters explore the Jurassic--Cretaceous tectonic evolution of southern Patagonia, which consists of a two-part history that begins with the development of a predecessor backarc rift basin (the Rocas Verdes Basin) and is followed by a successor retroarc foreland basin system (the Magallanes--Austral Basin). Chapter 1 investigates the geochronology of rifting in the predecessor Rocas Verdes Basin from the northern (Austral) basin sector to assess the basin-scale, along-strike variability in relative timing and duration of Jurassic--Early Cretaceous rifting. Chapter 2 examines the distribution of deep-water facies and the relative timing of deposition that represents the transition to, and development of, foreland basin sedimentation in the Magallanes--Austral Basin. Chapter 3 explores the role of longitudinal vs. transverse sediment supply during the early evolution of the Magallanes--Austral foreland basin system. Finally, chapter 4 examines along-strike variations in the provenance, timing of deposition, and distribution of facies within a deep-water canyon channel system represented by the Upper Cretaceous (Turonian--Santonian) Cerro Toro Formation.

Keywords: Geological and Environmental Sciences.
Advisor: Graham S. A. (Stephan Alan)
Grove Marty
Lowe Donald R.
Convergence rates of a class of multivariate density estimators based on adaptive partitioning [electronic resource]

Density estimation is a fundamental problem in statistics. It is a building block for other statistical methods, such as classification, nonparametric testing, and data compression. In this dissertation, I focus on a non-parametric approach to multivarite density estimation, and study the asymptotic behavior of this approach under both frequentist and Bayesian settings. The estimated density function is obtained based on consideration of a sequence of approximating spaces to the space of densities. The approximating spaces consist of piecewise constant density functions supported by binary partitions with increasing complexity. The partition is learned by maximizing either the likelihood of the corresponding histogram on that partition, or the marginal posterior distribution of the partition under a suitable prior. We analyze the convergence rate of the maximum likelihood estimator and the posterior concentration rate of the Bayesian estimator, and conclude that for a relatively rich class of density functions the rate does not directly depend on the dimension. Another result has significant practical implications: We show that the Bayesian method can adapt to the unknown complexity of the density function, thus achieving an optimal convergence rate without any prior information. We also apply this method to several specific problems, including spatial adaptation, estimation of functions of bounded variation, and variable selection.

Keywords: Statistics.
Advisor: Wong Wing Hung primary advisor. Thesis advisor
Candès Emmanuel J. (Emmanuel Jean) advisor. Thesis advisor
Diaconis Persi advisor. Thesis advisor
Convex optimization for Monte Carlo [electronic resource] : stochastic optimization for importance sampling

In Monte Carlo simulations it is often essential that a method is accompanied by an appropriate variance reduction method. Reducing the variance of a Monte Carlo method is, at least conceptually, an optimization problem, and mathematical optimization has indeed been used as a theoretical and conceptual tool in this pursuit. However, traditional Monte Carlo methods have only used numerical optimization sparingly, and convex optimization even less. Numerical optimization is study of algorithms for finding a solution to an optimization problem, as opposed to the study of analytical solutions of an optimization problem. Convex optimization is the study of convex optimization problems, a subclass of optimization problems for which efficient algorithms for finding the global optimum exists. In this work we present a framework for using convex optimization for Monte Carlo. More specifically, we present a framework for using stochastic convex optimization for adaptive importance sampling, self-normalized importance sampling, and what-if simulations. The main idea is to perform importance sampling and numerical optimization simultaneously. In particular, the numerical optimization does not rely on blackbox optimization solvers, and this allows the computational cost of each iteration to remain cheap. Because the optimization is performed on a convex problem, we can establish convergence and optimality.

Keywords: Computational and Mathematical Engineering.
Advisor: Boyd Stephen P. primary advisor. Thesis advisor
Duchi John advisor. Thesis advisor
Owen Art B. advisor. Thesis advisor
Correlated X-ray Scattering of Metallic Nanoparticles at the Stanford Synchrotron Radiation Lightsource

This thesis reports on the results of a new method for interpreting x-ray scattering data as applied to silver and platinum nanoparticles. Correlated X-ray Scattering (CXS) is the subject of much interest due to the possibilities of imaging un-crystallized proteins. CXS can also give much more detailed information about the structure of nanoparticles than more traditional solution scattering x-ray techniques, and could thus be immensely helpful in industrial/technical studies. With their femtosecond pulses of high intensity x-rays, x-ray Free Electron Lasers (XFEL) are the obvious choice for CXS studies due to the large numbers of photons and short exposure times necessary for this technique. For applications, however, it is important to figure out when it is possible to use the much more common and cheaper, albeit less powerful, synchrotron x-ray sources. This experiment attempts to use the method of difference correlations on data from solutions of platinum and silver nanoparticles to see if meaningful and interesting data can be extracted using CXS with synchrotron radiation. It is shown that with proper filtering techniques it is possible to extract a CXS signal from nanoparticle data. From this signal the finer details of the internal structure of these nanoparticles were determined, including observation of twinning structures. Although it requires specific and careful sample preparation to a very high concentration, CXS is an extremely promising x-ray scattering technique with a wide variety of possible applications.

Keywords:  Department of Physics
Correlated X-ray Scattering
x-ray scattering
nanoparticles
Thesis
Advisor: Doniach Sebastian
Fox John
Coupling electrochemistry and desorption electrospray ionization mass spectrometry to observe transient electrochemical intermediates [electronic resource]

The observation of electrochemical reaction species directly after electrochemical generation has been a goal of electrochemists for years, and is a problem that has been approached using many different analytical techniques. The challenge in acquiring faster response times exists in transferring electrochemically generated species quickly from solution to the gas phase for MS detection. The development of DESI allows for analyses to be made on surfaces under atmospheric pressure and at room temperature with a sampling time on the order of milliseconds. In collaboration with Prof. Hao Chen, we present a new DESI-ECMS technique for the mass spectrometric detection of fleeting reaction intermediates in electrochemical reactions utilizing a "waterwheel" working electrode setup is presented here. This setup takes inspiration from DESI-MS to sample directly from the surface of a working electrode for in situ electrochemical mass spectrometric analysis in seeking shorter analysis timescales. A number of systems is presented here verifying the viability of the waterwheel for DESI-ECMS analysis to observe fleeting electrochemical intermediates.

Keywords: Chemistry.
Advisor: Zare Richard N. primary advisor. Thesis advisor
Dai Hongjie
Fayer Michael D. advisor. Thesis advisor
Coupling isotachophoresis to reaction and separation assays [electronic resource]

Molecular diagnostics are rapidly growing with applications in disease detection, genetic profiling, forensic investigation, and various research purposes. These techniques include PCR, sequencing, antibodies, and hybridization assays, and offer exquisite sensitivity and multiplexity. However, widespread adoption of molecular diagnostics is constrained by a number of key challenges. Assay times often take 16 hours or more, due to slow second order hybridization kinetics as well as time-consuming sample preparation methods. Furthermore, sample preparation itself is laborious, requiring manual intervention by highly-skilled personnel at several steps in the workflow. This dissertation discusses approaches that leverage isotachophoresis (ITP) and its coupling to at least one other assay step with an aim to significantly reduce analysis times and complexity of molecular detection assays. ITP is an electrokinetic technique which uses a heterogeneous buffer system to preconcentrate and separate ions based on their electrophoretic mobilities. In the first part of this dissertation, we present a simple analytical model to describe accumulation and reaction rates in ITP. This model is useful in the design of ITP experiments, and enables a user to make informed decisions regarding optimal sample placement in ITP assay design. In the second part of this dissertation, we describe a novel approach that leverages ITP to accelerate chemical reactions and also use an ionic spacer to separate reaction products. We first demonstrate this approach using synthetic DNA targets, and show high-sensitivity detection in a 10 min assay. We then extend this technique and use high-mobility probes to recruit typically non-focusing species (such as proteins) into ITP. We demonstrate this assay using C-reactive Protein (CRP) in buffer as well as in diluted serum. We also present a numerical and analytical model to describe ITP assays that involve non-focusing targets recruited into ITP. The last part of this dissertation shows how ITP purification can simplify sample preparation protocols and integrate with downstream analysis methods. We first show size-based RNA fractionation using ITP in a 10 min assay. We use a commercial electrophoresis system to analyze resulting sample fractions. Finally, we show how ITP purification can extend the applicability of recombinase polymerase amplification (RPA) to whole blood samples. We demonstrate lysis, purification, and detection of inactivated Listeria Monocytogenes cells from whole blood using ITP and RPA.

Keywords: Mechanical Engineering.
Advisor: Santiago Juan G. primary advisor. Thesis advisor
Marshall Lewis A.
Pruitt Beth advisor. Thesis advisor