VictorJuiz/thesis huggingface dataset:
Synthesis and Chemical Modification of Boron Nitride and Graphene Aerogels and Related Nanostructures

Aerogels based on boron nitride and graphene can integrate macroscopic amounts of nanomaterial into a single, relatively open, multifunctional structure. Such aerogels possess the textural properties typical of aerogels including high surface area, high porosity, and low density. Most importantly, they are capable of retaining a number of the extraordinary properties of their nanomaterial building blocks. For example, boron nitride-based aerogels are electrically insulating while graphene aerogels are highly electrically conductive. These properties make the aerogels particularly promising for a variety of applications in supercapacitors, batteries, catalysis, gas sensing, gas storage, polymer composites, and water treatment. However, in order to optimize their performance in these applications, chemical modification is usually necessary./n/nThis dissertation explores chemical modification of graphene and boron nitride aerogels with the goal of being able to introduce targeted chemical modifications in order to improve the performance of the aerogel for specific applications. Additionally, the synthesis of new classes of aerogels is investigated./nExamples of chemical modification of graphene aerogels are the introduction of chemical dopants like boron, or the controlled formation of defects, often called defect-engineering (Chapter 3). These types of chemical modifications are particularly advantageous for highly sensitive and selective NO2 detection. New compositions of aerogels with electronic properties predicted to be intermediate between graphene and BN are possible by synthesizing boron carbon nitride aerogels (Chapter 4). Two chemically and electronically disparate materials can also be coupled to one another by the formation of multifunctional core-shell hybrids. Chapter 5 discusses the synthesis of photocatalytic graphitic carbon nitride shells on top of graphene aerogels cores for photocatalytic applications. In addition to chemical modification, physical modification is an approach to control the macroscopic properties of graphene and boron nitride aerogels. Chapter 6 explores density-tuning of graphene and boron nitride aerogels in order to tune the thermal conductivity for polymer composite applications./nIn addition to aerogels based on 2D nanomaterials, 1D nanomaterials can also serve as aerogel building blocks. Chapter 7 discusses a new approach to synthesize aerogels based on 1D nanofibers of an organic semiconductor, as well as a treatment method to convert them into carbon nanofiber aerogels. Lastly, Chapter 8 discusses the functionalization of BN nanostructures including BN aerogels, BN nanotubes, and BN nanosheets in order to improve the interfacial interactions between BN nanofillers and host polymer matrices in polymer composites for thermal interface materials.

Advisor: Zettl, Alex
Alivisatos, A. Paul
Media/Fetish: A Postcolonial Archeology of New Media and Africa

Media/Fetish analyzes the history of media technologies in anglophone West Africa with a special emphasis on Ghana from the early twentieth century to the present. Each chapter examines representations of a different media technology—gramophones, cinema, television, and mobile phones—at the time when they were new. Through an engagement with African studies, critical race theory, and postcolonial studies, Media/Fetish addresses a recurring deficiency in the history and theory of new media. By reorienting the emphasis from historical moments of invention, which tacitly privilege Euro-American ontologies of new media, to the analysis of the meanings of media technologies once they are adopted and adapted, Media/Fetish shows how the world is structured by new media use in Accra as much as it is by new media design in Silicon Valley. I argue that media have, in part, been made “new” by their discursive relationship to racialized development narratives. Be it the colonial civilizing mission to bring Western knowledge to Africans through mobile cinema or the promise of black uplift through the formation of Ghana’s national television, race has been crucial to global theories of new media.

Advisor: Doane, Mary Ann
Multilevel Pathways to Patient-Centered Care

Patient-centered care represents a paradigm shift for healthcare as the field undergoes massive restructuring to align health services delivery systems with the health of the patient as conceptualized by the biopsychosocial model rather than the biomedical model. As paradigm shifts cannot be implemented in a piecemeal manner, members within healthcare organizations are at risk of initiative fatigue. To understand how to facilitate the implementation of patient-centered care, this dissertation consists of three papers addressing factors that impact patient-centered care at macro, meso, and micro levels. The first paper, “Patient-Centered Culture at Physician Practices During Interconnected Changes in Ownership, Size, and Specialty Mix,” was the first large, longitudinal study to simultaneously assess the effects of changes in size, ownership, and specialty mix on practices’ use of strategies to improve responsiveness to patients using difference-in-difference regression. Increases in practice size, rather than changes in ownership or specialty mix, were associated with decreased patient responsiveness. The implication is that modular organization designs may mitigate the risk of decreased patient-centeredness when practices transition ownership from physicians to systems. The second paper, “Primary Care Team Participation and Patients’ Experience of Chronic Illness Care,” uses hierarchical linear regression to examine the relationship between participatory communication among interprofessional primary care team members and patients’ experiences of chronic illness care. Rather than a synergistic relationship as hypothesized, the results indicate that more participatory communication among team members does not translate into better patients’ experiences of chronic illness care. For the third paper, “Patient Activation as a Pathway to Shared Decision-making among Adults with Diabetes or Cardiovascular Disease,” cross lagged panel models are used to estimate asymmetries in the bidirectional relationship of patient activation and patients’ experiences of shared decision-making among adults with diabetes and/or cardiovascular disease. Patient activation has a much stronger impact on patients’ experiences of shared decision-making than the reverse. The implication is that primary care practices should target shared decision-making interventions at activated patients, while prioritizing patient activation among patients with low activation. In conclusion, patient-centered healthcare might be best conceptualized as a complex adaptive system. People must be empowered to make decisions when their local circumstances are too complex for centralized control and information must be shared in the process to ensure efficient adaptation. The primary role of healthcare organizations in such a context is to establish guiding principles and enabling structures. Practice and research implications are discussed within this framework of healthcare as a complex adaptive system.

Advisor: Shortell, Stephen M
Essays in Macroeconomics: Monetary Policy in a Recessionary Environment.

In this dissertation I study recessionary environments in general, placing a special emphasis on the steps that can be taken by policy makers to alleviate the negative consequences of recessions. After the Great Recession, most advanced economies had a prolonged period of low growth and high unemployment that is slowly subsiding. Several economists have proposed the possibility that the economy has entered a regime of "secular stagnation" where demand factors and the Zero Lower Bound lead to persistently low growth. Given the current worldwide decline in interest rates, secular stagnation is a looming risk that should be taken seriously, as it would have a significant impact on welfare. All chapters of this dissertation relate to these issues. The first chapter provides a general motivation of the topic and discusses the relationships between the remaining chapters. In the second chapter, "Going Negative at the Zero Lower Bound", I investigate whether negative rates can provide an antidote against the ZLB, granting monetary authorities more room to perform expansionary policy and combat demand-induced low growth. In the third chapter, "The Cyclical Sensitivity in Estimates of Potential Output", I study whether potential output really decreases permanently after prolonged recessions, or if, in contrast, this is a byproduct of a faulty computation of potential output. I also study whether some structural VAR methodologies can avoid these shortcomings. In the fourth chapter, "Neo-Keynesian Trade", I build a dynamic model that unifies a detailed trade pattern across regions and sectors with monetary non-neutrality. The nominal friction, a downwardly rigid wage, can lead to unemployment in the face of a negative shock if the monetary authority is unwilling or unable to inflate the economy, and this effect can vary substantially across regions depending on their industrial composition. Overall, the evidence in this dissertation indicates that policy makers should do more to combat slow growth, and that they have tools to do so.

Advisor: Gorodnichenko, Yuriy
Combinatorial and Algorithmic Aspects of Hyperbolic Polynomials

We explore connections between hyperbolic polynomials and computer science problems involving optimization and counting. Specifically we investigate the following diverse set of topics, all of which are connected through the modern study of hyperbolic polynomials:/n\textbf{Independent Sets}. To count independent sets of graphs, we study a multivariate generating polynomial for independence sets and prove generalizations of results of Chudnovsky and Seymour relating to real-rootedness of the polynomials./n\textbf{Differential Operators}./nIn the study of spectral graph theory and spectral discrepancy theory, the classical additive convolution is used to study the effect differential operators have on the roots of real rooted polynomials. We refine some existing tools for studying the movement of max root under differential operators and establish some conjectures for controlling the inner roots./n/n\textbf{Finite Difference Operators}. Lamprecht studies a/n$q-$extension of the classical multiplicative convolution which abstracts classical results. We extend the study of such generalizations by considering a finite-mesh preserving generalization of the classical additive convolution./n\textbf{Membership Algorithm}. We initiate a conversation around developing algorithms to solve fundamental tasks in this field by establishing an exact arithmetic polynomial time algorithm to determine whether a given bivariate polynomial is real-stable. By the characterization theorem of Br{\"a}nd{\'e}n and Borcea this is equivalent to an algorithm for testing whether a given linear transformation $T: \R_d[x] \to \R[x]$ sends real rooted polynomials to real rooted polynomials./n\textbf{Convex Optimization Complexity}. Given a hyperbolic polynomial one can do convex optimization over its hyperbolicity cone. The exact algorithmic relationship between semidefinite programming and hyperbolic programming is an open question. In an attempt to further motivate complexity questions between these two primitives we give a random family of polynomials which require exponentially sized approximate semidefinite representations for their hyperbolicity cones.

Advisor: Srivastava, Nikhil
Sharp and Practical Performance Bounds for MCMC and Multiple Testing

With the greater adoption of statistical and machine learning methods across science and industry, a greater awareness of the need to align statistical theory ever more closely with the demands of applications is developing. One recurring theme within this process is the re-examination of basic questions and core assumptions through the lens of modern mathematical statistics. This thesis targets two such basic questions in two different contexts: posterior simulation using Markov chain Monte Carlo (MCMC), on the one hand; and multiple hypothesis testing, on the other. For MCMC, we analyze convergence in terms of the expectations of a limited number of query functions, rather than the entire posterior. We show both theoretically and via simulations that the resultant theory predicts the required chain length more sharply than global convergence criteria. Furthermore, we provide match- ing lower bounds that show our bounds are essentially optimal in their dependence on chain parameters and target accuracy. For multiple testing, we provide the first general framework for establishing the optimal tradeoff between false positives (measured by the False Discovery Rate, or FDR) and false negatives (measured by the False Non-discovery rate, or FNR). We begin by proving some of the first non-asymptotic results available on this topic – initially in the context of Gaussian-like test statistics. We then go on to develop the more general framework. The latter applies to test statistics with essentially arbitrary analytic forms and dependence, recovers previous results as special cases, and yields numerically simulable lower bounds that can be evaluated in almost any model of interest.

Advisor: Jordan, Michael I
Methodologies for the evaluation of nuclear waste management strategies and applications to advanced fuel cycles

One of the unresolved hurdles facing present and future nuclear energy systems is waste management. Recent efforts to identify promising fuel cycles have attempted to value waste management through metrics reflecting intrinsic characteristics of the wastes rather than the environmental impacts, risks, and challenges involved in their disposal. This dissertation applies three waste management models to a broad set of fuel cycle options to explore the relationship between fuel cycle characteristics and waste disposal. First, long-lived fission product inventory is used as a proxy for repository performance, avoiding the computational expense and complexity of a full performance assessment. Second, the attractiveness for diversion and recovery of fissile materials from waste streams for potential proliferation is evaluated using a figure of merit, which values the quality of the material and its retrievability. Finally, repository area and surface storage requirements are determined based on thermal constraints for waste disposal in three geologic environments./nThese models are used to analyze fuel cycle options taken from the Fuel Cycle Evaluation and Screening (FCES) study. A Python package has been developed to characterize waste streams using FCES data including mass balances, discharged fuel composition(s), and details about fuel cycle technologies such as reactor type and reprocessing method. The package extends the FCES mass flow calculations to include waste package loading for spent fuels and waste loading fraction for high-level wastes. Benchmarking against FCES metric results demonstrates good agreement./nThe long-lived fission product inventory is shown to be sensitive to reactor thermal efficiency — because reactors that are less efficient are required to produce more fissions — and to the extent of recycling, because the recycled fissile material generally has greater long-lived fission product yield than enriched uranium. Specific fission product isotopes demonstrate sensitivity to fuel isotope, neutron spectrum, and residence time. Fissile material in all waste streams is shown to become attractive for recovery from waste as the self-protecting dose rate decays, but the time before that occurs is longer for high-level wastes that concentrate highly radioactive nuclides. Because high-level wastes are more dilute in fissile material, more waste packages need to be intercepted to obtain usable quantities of fissile material. The area and storage time requirements are shown to be highly sensitive to thermal properties and constraints of repository design. Fuel cycles recycling long-term heat-generating transuranic isotopes in fast reactors perform well, whereas those that utilize limited- recycling of actinides perform poorly. Parametric analysis of waste package and waste form loading with respect to these metrics demonstrates opportunities for the integration of fuel cycle operations and waste management.

Advisor: Fratoni, Massimiliano
Unraveling the Contribution of Morphological Awareness to Reading: A Longitudinal Analysis of Word-Level Outcomes for Latent Profiles of Young Readers

Theories of English literacy development assume that both phonological awareness and morphological awareness are metalinguistic skills involved in word identification. While there is robust empirical evidence supporting the key role of phonological awareness in reading, there is a smaller – though growing - body of empirical evidence suggesting morphological awareness makes a unique contribution to word identification. Much of the morphological awareness research has focused on its contribution to decoding in general; analysis of its specific role in the identification of different word types (i.e., morphologically complex words compared to non-morphologically complex words; real words compared to pseudowords) is inconsistent and limited. This study aims to fill this gap by examining Grade 2 students’ accuracy reading a variety of word types, controlling for morphological awareness, phonological awareness, and verbal cognitive ability. Results suggest that morphological awareness contributes to the recognition of morphologically complex and non-morphologically complex real words, but not to pseudowords. Also crucial to the field of morphological awareness research is a more developed understanding of the reader. Latent profile analysis was used to empirically determine unique student profiles of phonological and morphological awareness ability. Reading outcomes (e.g., decoding accuracy and reading comprehension) were analyzed longitudinally for each profile, across Grades 2-4, a critical developmental period when learning to read. Students in the morphologically dominant group and the phonologically dominant group performed similarly across time on all outcome measures. Students with commensurate development of these skills outperformed the other two groups on all measures at all time points, suggesting both skills are needed for higher levels of reading achievement during elementary school grade levels. Because many students struggle learning to read, this finding is useful in identifying the different skill profiles that are more or less at-risk for future reading outcomes.

Advisor: Cunningham, Anne
Bui, Yvonne
Biochemical characterization of the KSHV late gene transcriptional activator complex

In the beta- and gammaherpesviruses, a specialized complex of viral transcriptional activators (vTAs) coordinate to direct expression of virus-encoded late genes, which are critical for the production of infectious virions. The vTAs in Kaposi’s sarcoma-associated herpesvirus (KSHV) are ORF18, ORF24, ORF30, ORF31, ORF34, and ORF66. While the general organization of the vTA complex has been mapped, the individual roles of these proteins, and how they coordinate to activate late gene promoters, remains largely unknown. Thus, we set out to determine the roles of ORF18, which is a highly interconnected vTA component and of ORF24, which is a putative structural and functional TATA-binding protein (TBP) mimic./nWe first performed a comprehensive mutational analysis of the conserved residues in ORF18. The mutants were largely selective for disrupting the interaction with ORF30 but not the other three ORF18 binding partners: ORF31, ORF34, and ORF66. Furthermore, disrupting the ORF18-ORF30 interaction weakened the vTA complex as a whole, and an ORF18 point mutant that failed to bind ORF30 was unable to complement an ORF18 null virus. Thus, contacts between individual vTAs are critical, as even small disruptions in this complex result in profound defects in KSHV late gene expression. These findings underscore how individual interactions between the late gene transcription components are critical for both the stability and function of the complex./nNext, we examined the mechanism by which ORF24 binds RNA polymerase II (Pol II). Previous work in our lab found that ORF24 is a modular protein that binds to viral late gene promoters through its central TBP-like domain. Residues in the N-terminus of ORF24 bind and recruit human Pol II to activate the expression of late genes. We found that ORF24 interacts directly with the heptapeptide repeats of the carboxy terminal domain of Pol II, suggesting that ORF24 may be involved in bringing Pol II to sites of active viral late gene transcription. Collectively, our data highlight how KSHV (and likely other gamma and betaherpesviruses) direct robust transcription of late genes via a unique and streamlined mechanism of pre-initiation complex assembly.

Advisor: Glaunsinger, Britt A
Methods for the Detection of the Epoch of Reionization

The Epoch of Reionization is one of the last unexplored eras of our Universe's history. Beginning about a billion years after the Big Bang, this epoch is characterized by the births of the first stars and galaxies, whose light subsequently altered the nature of the gas surrounding them. There are several experiments aiming to detect the phase transition of this gas as it changes from neutral hydrogen to ionized hydrogen. Such a detection would open a wealth of information about our early Universe, revealing details about the nature of the first luminous sources and the evolution of structure formation./nInterferometers such as the Precision Array for Probing the Epoch of Reionization (PAPER) and the Hydrogen Epoch of Reionization Array (HERA) seek to measure the 21 cm signal from neutral hydrogen and map its evolution over spatial and temporal scales. A detection of reionization, however, is a difficult measurement. Though the 21 cm signal is a powerful 3D probe of the intergalactic medium, it is easily buried underneath bright foreground signals and instrumental systematics. A clean detection of reionization is ambitious and requires analysis methods that maximize data sensitivity and increase confidence in results./nThe work presented in this thesis addresses many of the key challenges that face the current field of 21 cm cosmology. This includes algorithms to locate contaminated data, methods to ensure accurate power spectrum measurements, and techniques for removing unwanted systematics while preserving the reionization signal. These developments serve as the foundation of the latest 21 cm measurements from the PAPER-64 and PAPER-128 arrays, whose results lie near the forefront of the field. These methods are also fundamental to HERA and future experiments, as they provide a strong foundation for the continued exploration of our cosmic dawn.

Advisor: Parsons, Aaron