VictorJuiz/thesis huggingface dataset:
Deformed D1D5 CFT: a holographic probe of quantum gravity

One of the big unsolved questions in gravity research is the black hole information problem. This problem, which pits the unitarity of quantum field theory against smooth classical spacetime, must have a solution in a complete theory of quantum gravity. This thesis will explore aspects of one approach to this problem in the context of string theory. The approach imagines black hole microstates as string theoretic objects. We look at a prototype system, the D1D5 system, and exploit holography to examine the dual conformal field theory (CFT). Specifically, we examine the CFT deformed from the free orbifold point, dual to a very stringy bulk, using a twisted operator that will take us towards the point with the supergravity description. The effects of twisted operators in the CFT are key to understanding physical processes such as emission and thermalization in black hole microstates. We will propose a component twist method for examining the effects of bare twist operators for higher twists in the continuum limit. Our method builds higher twists from simple 2-cycle twists, whose effects are known. We will find that, in this limit, the coefficients describing general states will follow a conjectured general functional form. We then explore the deformed CFT directly by examining operator mixing for untwisted operators. We will exploit the operator product expansion on the covering space, where twist operators of the orbifold are resolved. We use this to examine the mixing of a general supergravity operator, specifically examine the dilaton, and finish with the mixing of a non-supersymmetric candidate operator. We conjecture that this method could be extended to include twisted operators. We will also examine the mixing of the non-supersymmetric candidate operator by examining three point functions. To automate the lengthy and repetitive computations, we wrote a Mathematica package to compute correlation functions and OPEs in the D1D5 CFT. We will explain some of the main functions of this package and how it can be applied to computations. Finally, we will end with a short discussion on future directions.

Keywords: black holes
conformal field theory
high energy physics
holography
quantum gravity
string theory
Advisor: Peet, Amanda W
Reading Between the Bits: Uncovering New Insights in Data for Efficient Processor Design

Three emerging trends pose challenges to the design of efficient processors. First, applications are executing on strictly energy-constrained hardware due to the rise of IoT and mobile computing. Traditional architectures expend a great deal of energy providing exactness despite the approximate applications that often run on these systems. Second, data sets are growing to enormous proportions due to the rapid gathering of user information in modern devices. We can no longer rely on data being readily available in on-chip computer storage. Third, active chip area is diminishing at smaller technology nodes due to power density limitations in process technology scaling. We can no longer fully utilize all on-chip hardware resources simultaneously. Our research tackles these challenges by recognizing that they stem from fundamental gaps in the way that data is contextualized in hardware. The goal of a processor is to process real-world information; yet in modern computers, hardware perceives data as nothing more than bits. Can the hardware tell if an integer is purely numerical or if it will be used as a memory address later? Can it tell that two elements are adjacent in a multidimensional data structure even though they are not stored contiguously? Can it tell if contiguous data elements will be accessed at the same time or accessed independently? Traditionally, hardware cannot interpret data bits on their own; it only interprets data bits by how instructions use them. It lacks an understanding of what information is encoded in the bits (functional context), where that information is located (spatial context), and when that information is needed (temporal context). Our research fills these gaps in data context to address the three challenges, recognizing that 1) functional context enables approximation for greater efficiency under tight energy constraints; 2) spatial context demystifies patterns and correlations to more efficiently and concisely process massive data sets; and 3) temporal context infers the criticality of data to allow for better utilization of precious on-chip resources.

Keywords: approximate computing
computer architecture
Advisor: Enright Jerger, Natalie
A miniaturized microfluidic cytometer platform for point-of-care blood testing applications

In recent years, microfluidic lab-on-a-chip devices have made tremendous progress. Many new features, new processes and fabrication methodologies have been proposed and realized in the last two decades. In the field of clinical diagnostics, however, there still lack devices and products that truly utilize microfluidic lab-on-a-chip technologies. My thesis is focused on developing a novel blood testing platform that can be commercialized as a point-of-care diagnostic tool using microfluidics and optical detection technologies. Access to laboratory quality blood testing has been difficult and sometimes prohibitive for many populations around the world, which lead to increased mortality, morbidity and healthcare cost. In this work, I research and developed a particle imaging and detection system using microfluidics to control sample motion. The system used fluorescence based detection methodology. A novel image analysis algorithm is proposed and implemented to detect and track particles captured by the optical detector. My thesis investigates the fluidic design, on-chip fluidic control, optical detection system and particle/cell counting algorithm. The overall system is designed to be capable of commercialized as a point-of-care portable blood analysis system deployed in remote health settings. In addition, CD4 T cell counting, which is the current gold standard in HIV/AIDS disease monitoring, is used as an example assay developed on the platform. A microfluidic chip, that can complete the cell counting analysis within 15 minutes directly from a single finger prick blood sample is designed, fabricated and characterized. This work also studies the sample preparation steps required for the cell counting assay and the impact of various system parameters. The system described in this thesis highlights a portable blood testing platform that can be further developed and commercialized as a clinical tool for cell, protein and nucleic acid based laboratory tests conducted at point-of-care. The outcome of this work demonstrates the feasibility and utility of such system or product in medical diagnostics in remote health settings.

Keywords: CD4
flow cytometry
global health
lab on a chip
microfluidics
point of care
Advisor: Aitchison, Stewart
The Costs, Benefits, and Efficiency of Air Quality Regulation

Air pollution poses serious risks to public health. Combatting it sensibly requires credible empirical estimates of the relevant costs and benefits. The intent of this thesis is to provide such estimates. Chapter 1 examines the value of reducing emissions from power plants, an important source of air pollution in several countries. Within a model of health, consumption, production, power generation, and resource extraction, I derive a 'sufficient statistics' formula for the change in social welfare due to a small reduction in emissions. The formula simplifies to a comparison of marginal benefits (in terms of reduced mortality risk, monetized using the value of a statistical life) and the marginal cost of abatement. I estimate these inputs using quasi-experimental variation induced by the Clean Air Interstate Rule, a policy that capped power plant emissions in the United States. Results indicate that further reducing those emissions would be worthwhile. Chapter 2 re-examines the effect of a county's regulatory status under the US Clean Air Act on the change in its air pollution concentration, the 'first-stage' underlying causal estimates of the benefits of reducing air pollution in several studies. Using data thought no longer to exist, I find that one of the commonly-used measurement approaches -- a regression-discontinuity estimator -- is invalid. The other commonly-used approach -- a difference-in-differences estimator -- delivers inflated estimates of the effects of regulation on air pollution. These findings suggest that the literature substantially understates the benefits of reducing air pollution. Chapter 3, joint with Robert McMillan, provides causal estimates of the effects of sustained exposure to severe air pollution on mortality risk. Our research design is based on the 'smoke control' provisions of the UK's Clean Air Act of 1956, which granted local authorities power to address emissions from the domestic chimney. We find that smoke control caused significant reductions in air pollution in areas that implemented it relative to those that did not. Our 2SLS estimates, which combine this exogenous variation in air quality improvements with local mortality data, indicate a significant reduction in probability of death. They are relevant when calculating air pollution's costs in coal-burning middle-income countries today.

Keywords: air quality regulation
Clean Air Interstate Rule
long-term exposure to air pollution
sufficient statistics
UK Clean Air Act
US Clean Air Amendments of 1970
Advisor: McMillan, Robert
Metal-containing and Metal-free systems for small molecule activation

The objective of this thesis is to investigate small molecule activation with metal-containing and metal-free systems. Chapter 2 describes a tri-aryl benzene ligand scaffold for multimetallic N2 activation. A RuCp* complex was synthesized and characterized by NMR and X-ray crystallography. It offered an easy entry to understanding of the ligand coordination environment. Additionally, several multi-iron complexes were also obtained even though they were not the desired products. However, they still demonstrated the feasibility of using this ligand to effect multimetallic chemistry. Chapters 3 to 5 describe a series of compounds with charge-separation feature. These compounds could not only bind CO2 reversibly, but also catalyze the hydroboration of CO2 with a wide borane scope. In Chapter 3, a possible intermediate from the catalytic cycle was isolated and it partly revealed the mechanism of the catalytic reaction.

Advisor: Song, Datong
Photothermal and Photochemical Nanostructured Catalyst Engineering Towards Efficient Solar Fuel Production

With global energy demand rising alongside the advancement of climate change, the conversion of greenhouse gas carbon dioxide into value-added chemicals and fuels is attracting increasing attention. The crux for the successful development of this promising technology is the exploration and discovery of highly active, selective, and stable catalyst materials. Herein we demonstrate that the reverse water gas shift (RWGS) reaction can be driven by Nb2O5 nanorod-supported Pd nanocrystals, without external heating, using visible and near infrared (NIR) light. By measuring the dependence of the RWGS reaction rates on the intensity and spectral power distribution of filtered light incident on the nanostructured Pd@Nb2O5 catalyst, we determine the RWGS reaction to be initiated by heat generated from thermalized charge carriers in the Pd nanocrystals that are excited by inter-band and intra-band absorption of visible and NIR light. We also demonstrate that the catalytic activity and selectivity of CO2 reduction to CO and CH4 products can be systematically tailored, by varying the size of the Pd nanocrystals, to acheive champion turnover frequencies (0.61 sâ 1) and efficient conversion of solar energy to stored chemical energy. The remarkable control over the catalytic performance of Pd@Nb2O5 stems from a combination of photothermal, electronic, and size effects. The insight gleaned from this detailed experimental-theoretical study provides a blueprint for how to tailor the performance metrics of earth-abundant, low-cost metal-metal oxide (M@M'Ox) analogues. Finally, we report a lattice strain and defect controlled strategy that enables the high-performance of low-cost photocatalystic materials. Lattice compressed ultrafine nonstoichiometric indium oxide dots, In2O3-x(OH)y, grown on the surface of niobium pentoxide nanorods were fabricated; the optimized hybrid structure exhibits 44-fold increase in efficiency compared with pristine In2O3-x(OH)y, along with extremely long-term operational stability, potentially originating from the increased number of active oxygen vacancies, prolonged excited-state lifetimes, and enhanced photo-generated carrier energies.

Keywords: CO2 conversion
niobium oxide nanostructure
palladium catalysts
Photothermal catalyst
solar fuels
tunable selectivity
Advisor: Ozin, Geoffrey
Perovic, Doug
Enhanced Column Filtration for Arsenic Removal from Water: Polymer-Templated Iron Oxide Nanoparticles Immobilized on Sand via Layer-by-Layer Deposition

Arsenic is ubiquitous in water sources around the world and is highly toxic. While precipitation and membrane filtration techniques are successfully implemented in developed cities, they are unsuitable for rural and low-resource settings lacking centralized facilities. This thesis presents the use of ultra-small iron oxide (Fe2O3) nanoparticles functionalized on sand granules for use as a house-hold scale adsorption filter. Water-stable Îą-Fe2O3 (hematite) nanoparticles (

Keywords: Arsenic
Discrete Gradient Surfaces
Iron Oxide
Nanoparticles
Polyelectrolyte Multilayer
Water Filtration
Advisor: Goh, M. Cynthia
BUILDING HEALTHIER RELATIONSHIPS WITHIN COMMUNITIES: THE CRITICAL EXAMINATION OF GUYANESE PERSPECTIVES ON ADOLESCENT DATING VIOLENCE AND ITS PREVENTION

Dating in adolescence is an experience that has been thought to provide positive opportunities to learn and enhance social and interpersonal skills. However, some adolescents are exposed to physical, psychological, sexual, and economic forms of violence in their dating relationships, which can lead to poor health outcomes for both perpetrators and victims regardless of gender, race, or class. To prevent such negative outcomes, adolescents as well as their communities need community-specific opportunities to discuss and tackle dating violence. While adolescent dating violence research has increased internationally, there remains a paucity of information for the Caribbean region. For this reason, I completed a critical exploratory qualitative study in Guyana, a country that has the highest reported incidence of domestic violence for the Caribbean. The aim of my study was to provide a contextualized understanding of the phenomenon, by examining how discourses on race, gender, age, and class shape perspectives on adolescent dating violence and its prevention. A postcolonial feminist lens guided this study and data collection included 6 key informant interviews and 8 focus group discussions with parents, teachers, school officials, and adolescents at a public secondary school. Students who attended this school were from low-to-middle income families in the city of Georgetown and surrounding areas. In total, the study had 36 participants (5 boys and 8 men; 10 girls and 13 women). Three key findings emerged: 1) community perspectives on dating violence are primarily shaped by dominant discourses on respectability, colonial discourses on gender norms, family, and education, resulting in dating being unacceptable during adolescence; 2) Current authoritarian interpersonal relationships between adults and adolescents limit the possibility of engaging in conversations on dating violence; 3) Adolescents are yearning for more information on dating relationships, however, parents and teachers lack institutional and social support to promote healthy relationships and environments, which leads to frustration and fatigue. I suggest that a more effective way of addressing adolescent dating violence in Guyana is to approach it as a community issue. This approach includes continuously questioning dominant discourses and social systems in Guyanese society and creating more opportunities for people to relate to each other in ways that promote less authoritarian interactions in the current environment.

Keywords: Adolescents
Caribbean
Dating Violence
Health Promotion
Intersectionality
Postcolonial Feminism
Advisor: Gastaldo, Denise
Applications of Renormalization to Irrationally Indifferent Complex Dynamics

This thesis comprises of two main results which are proved using renormalization techniques. For the first result, we show that a quadratic polynomial with a fixed Siegel disc of bounded type rotation number is conformally mateable with the basilica polynomial f_B(z) := z^2-1. For the second result, we study sufficiently dissipative complex quadratic HĂŠnon maps with a semi-Siegel fixed point of inverse golden-mean rotation number. Gaidashev and Yampolsky showed that the Siegel disks of such maps are bounded by topological circles. We investigate the geometric properties of such curves, and demonstrate that they cannot be smooth.

Keywords: Complex dynamics
Dynamical systems
Renormalization
Advisor: Yampolsky, Michael
Work-Family Enrichment Training: Promoting Transferability of Resources across Life Domains

The goal of this work was to examine intentional resource transfer across work and family roles. This was accomplished by devising and evaluating a work-family enrichment training program designed to enhance the transfer of resources acquired in the work role to improve outcomes in the family role. The first phase of this work established the need for enrichment training by drawing on boundary theories (Ashforth, Kreiner, Fugate, 2000). Findings from 261 employees across two experiments indicated that negative interrelations between work and family roles were more prominent than positive interrelations, that is, individuals perceived the work-family interface in more negative terms than positive terms. Individuals also reported higher conflict, but not enrichment, between their work and family roles than between within-work or within-family roles. These findings support the need for promoting work-family enrichment through training initiatives. The second phase of this work drew from social cognitive theory (Bandura, 1986) and involved the development and evaluation of a work-to-family enrichment training, based on Greenhaus and Powellâ s (2006) enrichment theory and interpersonal capitalization theory (e.g., Ilies, Keeney, Scott, 2011). The program was administered to 163 administrative employees at a large North American university using a pre-post experimental design. Consistent with the hypotheses, findings indicated that, compared to a control training, the enrichment training increased development-based enrichment from work to family (the beneficial transfer of skills, knowledge and values). Further, the effect of the training on both development-based and affect-based enrichment (the transfer of positive affect) was mediated by enrichment self-efficacy. This effect was moderated by initial social-emotional work resources, such that the training was more effective for individuals perceiving a relatively low level of such resources. Finally, as hypothesized, enrichment self-efficacy and enrichment sequentially mediated the effect of the training on two remote outcomes: work-family pride and job satisfaction. This work advances enrichment theory by demonstrating that human agency can facilitate resource transfer across roles. From a practical perspective, this study is the first to develop and test a work-family enrichment training, which can serve as a tool for individuals and organizations to increase awareness and boost performance and satisfaction.

Keywords: training
work-family enrichment
work-family enrichment self-efficacy
work-family intervention
Advisor: McCarthy, Julie M.
Novel Phases from the Interplay of Topology and Strong Interactions

In recent years, topology has become increasingly prevalent in condensed matter physics. It has allowed us to understand, and even predict, a variety of striking and remarkable physical phenomena. The study of strongly interacting systems has similarly lavished us with a diverse range of exotic phases and unconventional transitions, many of which are still poorly understood. In this thesis we will explore the interplay between topology and interactions in an effort to uncover new and novel phases. First we study how interactions impact the quantum phase transition between a topologically non-trivial phase and a trivial phase. The combination of interactions and the low-energy degrees of freedom associated with the transition leads to the emergence of a dome of lattice-symmetry breaking nematic order. Such behaviour is reminiscent of a number of strongly correlated electronic systems. We move on to study the strongly interacting limit of one of the earliest and best-known non-interacting topological phases, Haldane's model of a Chern insulator. Recently realized with ultracold atoms in a shaken optical lattice, the model has a non-trivial topological invariant associated with its band structure. In the strongly interacting limit the spin degrees of freedom are all that survive and we find a rich phase diagram of magnetically ordered phases, using a combination of both classical and quantum techniques. Supplementing the model with an additional term we can `quantum-melt' one of these ordered states to produce a disordered, liquid state that we positively identify as a chiral spin liquid, a highly entangled state of matter with fractionalised excitations. We generalise this mechanism to other two dimensional lattices, uncovering a possible unifying framework with which to understand the emergence of chiral spin liquids in lattice spin models. Finally, motivated by groundbreaking experiments in the ultracold atoms community, we investigate a model of two-component bosons with an artificial spin-orbit coupling. The interplay between the lattice, interactions and spin-orbit coupling produces a variety of unusual superfluid phases. Using a novel Monte Carlo technique we reveal the finite temperature phase diagram that appears close to the Mott transition.

Keywords: Artificial Gauge Fields
Exact Diagonalization
Monte Carlo
Quantum Spin Liquids
Strongly Correlated Systems
Topological Phases
Advisor: Paramekanti, Arun