VictorJuiz/thesis huggingface dataset:
Quantifying Pacific Ocean nitrous oxide cycling using intramolecular isotope measurements and modeling
Keywords: Sustainability.
Earth System Science.

Nitrous oxide is one of the lesser-known greenhouse gases, yet its potential to warm the environment, on a per-molecule basis, is immense. Marine nitrous oxide production is concentrated in and around oxygen deficient zones, whose steep redox gradients allow for overlapping microbial processes that produce nitrous oxide. But the rates of these processes, and their relative importance in contributing to hotspots of nitrous oxide production, remain uncertain. This dissertation uses the intramolecular nitrogen isotopes (or isotopomers) of nitrous oxide to quantify its production in and around the eastern tropical North Pacific oxygen deficient zone. In Chapter 1, I find that high, near surface accumulations of nitrous oxide in this region are produced mainly by denitrification, with a smaller contribution from nitrification. In some core anoxic depths of the oxygen deficient zone, nitrous oxide cycling is not in steady state, while elsewhere, the isotopic content of nitrous oxide can be explained by denitrification with a positive site preference. In Chapter 2, I present a software package for isotopomer data processing and discuss the performance of this software. Ammonia-oxidizing archaea can produce nitrous oxide via a hybrid mechanism, so-called because it combines nitrogen derived from ammonium and nitrite to form nitrous oxide. In Chapter 3, I show that hybrid nitrous oxide production is inhibited by oxygen and reaches high yields at oxic-anoxic interfaces where ammonia oxidation is active. Integrating the information learned from these biogeochemical measurements, Chapter 4 presents a 1D advection-diffusion-reaction model constrained with nitrous oxide isotopomers to quantify nitrous oxide cycling in the eastern tropical North Pacific and test the sensitivity of that cycling to ocean deoxygenation and changes in organic matter export. Together, the results described in this dissertation show that nitrous oxide cycling in this region is a dynamic system that depends on low oxygen conditions and an organic matter source, conditions subject to change with ocean warming, deoxygenation, and increasing atmospheric N deposition. The constraints and parameters identified in this dissertation should provide a starting point for better implementations of nitrous oxide cycling in global biogeochemical models, making it possible to predict feedbacks between marine nitrous oxide cycling and climate change
Quantitative analysis of observed filamentation structure in high energy electron beam-plasma interaction
Keywords: Engineering.
Mechanical Engineering.

Filamentation instability is a primary candidate mechanism that contributes to the dynamics of collisionless shock. It is of great significance to study the dynamics in the shock front, since the filaments are populated there. This mechanism is responsible for various cosmological physics phenomena and high-energy density physics, such as inertial confinement reactions, gamma burst. This report presents the first experimental evidence of filamentation structure formed by relativistic electron beam-plasma interactions. This study, conducted at the Omega laser facility at the University of Rochester, focuses on dynamics of a hot electron beam interacting with uniform, slowly expanding plasma electrons. Drawing from an extensive literature review on theoretical and simulation studies of Filamentation instability in relativistic high-energy physics, the observations and analysis from this experiment reveal a filamentation structure with a spatial scale range from 0.150 - 0.350 nm. Its linear stage persists for 50 ps, which serves as its temporal scale. Diagnostic methods, including the Electron-Positron-Proton spectrometer and proton radiography, have been employed. Further analysis for retrieving the magnetic field strengthen has been reported as of the order of O(0.8) T. This findings identify the regime where electron Filamentation instability is ongoing and provide valuable data for future exploration.
The quantum anomalous Hall effect : uses in electrical metrology and understanding residual dissipation
Keywords: Humanities and Sciences.
Physics.

When a company manufactures and sells a resistor, they typically aim to traceably link its resistance value to a quantum Hall (QH) effect measurement. When a thin semiconductor is cooled to a low enough temperature and exposed to a large enough magnetic field, it exhibits zero longitudinal resistance and quantized Hall (transverse) resistance. This quantized resistance is a topological phenomenon, insensitive to sample details, and since 1990 has been used to define the ohm. Magnetic topological insulators exhibit the same resistance properties, but at zero magnetic field — this is the quantum anomalous Hall (QAH) effect. QAH materials offer significant advantages as possible replacements for QH resistance standards. Eliminating the need for large magnetic fields not only allows simplifying measurement infrastructure, but also allows a quantum resistance standard to be directly integrated with a Josephson voltage standard to produce a quantum current standard. However, all measurements of the QAH effect to date have observed non-zero longitudinal resistance despite quantization of the Hall resistance to h/e^2 (where h is Planck's constant and e the electron charge) being confirmed to within one part per billion. This residual dissipation is strongly temperature-dependent, lowering the temperature at which the QAH effect is well-quantized and thus limiting industrial applications. This dissertation will focus on our efforts to understand and find metrological applications for the QAH state of the canonical magnetic topological insulator — Cr-doped (Bi,Sb)2Te3. The nature of non-equilibrium dissipationless current flow in this system will be explored by comparing the measured potential profile in a QAH Hall bar to numerical simulations of the Poisson equation. Separately, residual dissipation will be studied by decoupling edge and bulk contributions using an annular geometry known as the Corbino disk. We will also show that despite their limitations, these materials are already useful within the field of electrical metrology. We will discuss how metrological measurements of resistance are made and highlight the construction of a novel quantum current sensor based on a single-cryostat combination of a QAH resistor with a programmable Josephson voltage standard.
Quantum chemistry and quantum simulation at scale : leveraging modern computing paradigms and hardware
Keywords: Humanities and Sciences.
Chemistry.

Quantum chemistry has strong connections to important technologies and applications like quantum computing, machine learning, chemical or materials design, and drug discovery. At the heart of these connections is an increase in high-performance computing (HPC) power, largely driven by accelerators like GPUs. Improving how quantum chemistry methods are formulated and implemented to use current and emerging computing power is therefore crucial. In this work, I focus on two directions: scaling quantum chemistry methods to distributed, GPU-accelerated hardware to enable studying large chemical systems, and using tensor network methods to simulate and study quantum circuits for quantum computing. The fast evaluation of electronic structure is essential for studying the dynamics of molecular systems, for reaction discovery, or for generating high quality training data for machine learning models. I develop a multi-node, multi-GPU implementation of the electron-repulsion integrals—the computational bottleneck in many electronic structure methods—using the task-based parallel programming language Regent. This allows performing a calculation that treats the entire green fluorescent protein (GFP) molecule (3000+ atoms) quantum mechanically with high parallel efficiency. I go on to parallelize across molecular systems by implementing a distributed client-server ab initio exciton model, and present results using this model to study the excited state dynamics of the LH2 light-harvesting protein complex. Quantum computers are a promising emerging technology, but while real quantum devices remain error-prone and composed of small numbers of qubits, classical simulations of quantum circuits are important for studying the behavior of quantum algorithms. Here I present work using a classical simulator built on tree tensor network methods to study quantum circuits. I discuss the benefits and relevance of approximate methods like tensor networks which represent a quantum state in a compressed form, and discuss insights on Shor's algorithm for integer factorization
Quantum control and characterization of phononic crystal cavities
Keywords: Humanities and Sciences.
Applied Physics.

The nonclassical behavior of mechanical objects is of both fundamental interest and potential technological utility. Mechanical resonators can be combined with superconducting microwave circuits to realize quantum technologies, acting as memories for computation and on-chip delay lines, with small footprints and large achievable coupling rates. The nonlinearity of the circuit enables quantum control of the mechanical mode, as well as nondemolition readout of the prepared mechanical states. This hybrid platform has seen great progress in recent years as both a flourishing technological avenue and as a platform to explore quantum behavior of mechanical motion. In this work, we describe a series of experiments which explore the versatile uses of a quantum acoustics platform built from piezoelectric nanomechanical resonators. First, we describe the design and experimental realization of a Purcell filter composed of lithium niobate Lamb-wave resonators. Next, we combine a superconducting transmon qubit with two phononic crystal resonators, also made of lithium niobate. We demonstrate full quantum control of the mechanical modes and perform quantum state tomography to extract the density matrices of the prepared states. In this effort, we also prepare and characterize a mechanical Bell-state between the two resonators, demonstrating a small-scale quantum acoustic processor. Last, using the same device, we use the qubit to perform phonon number-resolved detection of dissipation and dephasing of coherent states in the mechanical oscillator. We develop a model showing that the dissipation signatures are consistent with emission into a small ensemble of long-lived two-level system defects, thus elucidating the need for further refinement of fabrication techniques. Altogether, this dissertation represents an exploration of a wide range of different applications for a hybrid quantum acoustic platform
Quantum controlled cold scattering between simple atoms and diatoms
Keywords: Chemistry.

This thesis presents the experimental studies of quantum-controlled cold scattering of H2 isotopologues (HD, D2) with simple rare gas atoms (He, Ne) and diatom molecules D2. In these experiments, we prepare HD and D2 molecules in specific rovibrational levels (v = 2, 4, j = 2, 4) with defined alignments, and study their rotational inelastic scatterings of the state-prepared molecules at low collision temperatures. From a time-of-flight apparatus, we extract information about the angular distributions of the scattered products, therefore providing insights into the dynamics of the collision processes. By combining quantum-state control and low-energy scattering, we are able to interrogate the fundamental interactions between such simple atoms and diatoms at an unprecedented level of detail. The thesis is structured as follows. Chapter 1 serves as an introductory point of the subject. A brief overview of the development and progress of cold scattering is given, and various techniques to achieve cold relative temperatures as well as quantum state control are discussed. The purpose is mainly to situate our experimental techniques in the broad field, and to demonstrate the similarities and difficulties we face. Chapter 2 presents the theoretical treatment of the scattering problem. They serve as the necessary background for analyzing the data in later discussions, and sometimes provide direct comparisons. Chapter 3 focuses on the experimental setup we use to achieve quantum-controlled cold scattering. Many details are elucidated at length. In the next two chapters (Chapter 4, 5), various experimental results of rovibrationally excited HD/D2 with other scattering partners are presented and discussed. Chapter 4 describes the Δj = 2 inelastic scattering results of D2 (v = 2, 4, j = 2, 4) with rare gas atoms He and Ne, as well as the Δj = 1, 2 relaxations of HD (v = 4, j = 2). Chapter 5 includes the scattering results between a pair of state-prepared diatoms D2 (v = 2, j = 2). In these two chapters, theoretical comparisons are provided alongside the data where available. In the last chapter (Chapter 6), we conclude the thesis with more thoughts on the summary and outlook of the project. Although complete satisfactory agreements between theory and experiments have not been necessarily achieved for all of the studies we present, we hope such discussions would inspire more future works of this kind
Quantum dynamics of broadband nonlinear photonics : from phenomenology to function
Keywords: Humanities and Sciences.
Applied Physics.

In this thesis, we address the question of what new physics is expected to emerge as optical nonlinearity continues to increase towards the single-photon-level nonlinearity and how we can utilize the dynamics of photons in such a regime. In particular, we put special emphasis on broadband nonlinear photonics, where ultrashort pulses in nonlinear waveguides can provide significant enhancement of nonlinear coupling via tight three-dimensional field confinement. As such strong nonlinearity naturally leads to quantum features in broadband optical fields, the main aim of this thesis can be more precisely summarized as understanding the phenomenology of multimode nonlinear quantum dynamics of photons and engineering novel functions by leveraging the phenomenology
Quantum parametric oscillators coupled in time and frequency domains
Keywords: Humanities and Sciences.
Applied Physics.

This dissertation collects a sequence of case studies on the physics of coupled networks of quantum parametric oscillators. In the first part, we review the relevant formalism used to describe quantum parametric oscillators and quantum networks. In the second part, we examine a family of architectures based on time-multiplexed parametric oscillators, more widely known as coherent Ising machines for solving hard optimization problems. In the third part, we consider two case studies in frequency-multiplexed networks: a microwave architecture in which couplings can be arbitrarily synthesized, and an optical system in which the collective excitation of many frequency modes come together to form an ultrashort pulse. In the last part, we explore the quantum dynamics of ultrashort pulses of light undergoing traveling-wave parametric interactions
Quantum simulation using hybrid metal-semiconductor islands
Keywords: Humanities and Sciences.
Applied Physics.

Advancements in our control and understanding of quantum systems promise dramatic change in technology, potentially affecting fields of computation, sensing, and even power transmission. These grand possibilities are driven by new phenomena that emerge from strong quantum mechanical interactions between electrons in a material. One limitation to realizing these breakthroughs is that much of the exotic behavior present in quantum materials occur in conditions not suitable for practical applications, for example, very low temperatures or high pressures. Understanding why these novel properties emerge may provide insight into overcoming such limitations. One avenue to better our understanding is quantum simulation, in which a highly controllable experimental system is used to directly implement the physics of these quantum materials. In this thesis we build on a new approach to quantum simulation, using hybrid metal-semiconductor island nanostructures. The hybrid structure combines the advantages of both metal and semiconductor nanostructures -- sites that behave uniformly and couplings that are highly tunable. Each island can act as a single lattice site, with electrons that may interact with other lattice sites or a surrounding bath of conduction electrons. However, before scaling to lattices where the physics of bulk materials can be replicated, a crucial step is understanding how two such islands interact with each other. To probe the inter-island interaction, we build and study a two-island device, and find that the inter-island interaction arises from a Kondo-like screening of charge states acting as a pseudospin. When each island is also coupled to a single lead via a Kondo interaction, the resulting competition leads to a quantum critical point. We find that this is well described by a double charge Kondo model, and our transport measurements well match numerical renormalization group calculations. In particular, we study how critical behavior is destroyed following a particular universal scaling form when detuning from charge degeneracy, where criticality occurs
Race and Ethnicity and Prehospital Use of Opioid or Ketamine Analgesia in Acute Traumatic Injury
Keywords: Matheson, Loretta
Emergency Medicne
Emergency medical services
Trauma
Pain
Opioids
Analgesia
Text
Thesis

Importance: Racial and ethnic disparities in pain management have been characterized in many hospital based settings. Painful traumatic injuries are a common reason for 911 activations of the EMS (emergency medical services) system.
Objective: To evaluate whether, among patients treated by EMS with traumatic injuries, race and ethnicity are associated with either disparate recording of pain scores or disparate administration of analgesia when a high pain score is recorded.
Design, Settings, and Participants: This cohort study included interactions from 2019 to 2021 for US patients ages 14 to 99 years who had experienced painful acute traumatic injuries and were treated and transported by an advanced life support unit following the activation of the 911 EMS system. The data were analyzed in January 2023.
Exposures: Acute painful traumatic injuries including burns.
Main Outcomes and Measures: Outcomes were the recording of a pain score and the administration of a nonoral opioid or ketamine.
Results: The study cohort included 4 781 396 EMS activations for acute traumatic injury, with a median
(IQR) patient age of 59 (35-78) years (2 497 053 female [52.2%]; 31 266 American Indian or Alaskan
Native [0.7%]; 59 713 Asian [1.2%]; 742 931 Black [15.5%], 411 934 Hispanic or Latino [8.6%], 10 747
Native Hawaiian or other Pacific Islander [0.2%]; 2 764 499 White [57.8%]; 16 161 multiple races [0.3%]). The analysis showed that race and ethnicity was associated with the likelihood of having a pain score recorded. Compared with White patients, American Indian and Alaskan Native patients had the lowest adjusted odds ratio (AOR) of having a pain score recorded (AOR, 0.74; 95% CI, 0.71-0.76). Among patients for whom a high pain score was recorded (between 7 and 10 out of 10), Black patients were about half as likely to receive opioid or ketamine analgesia as White patients (AOR, 0.53; 95% CI,
0.52-0.54) despite having a pain score recorded almost as frequently as White patients.
Conclusions and Relevance: In this nationwide study of patients treated by EMS for acute traumatic injuries, patients from racial or ethnic minority groups were less likely to have a pain score recorded, with Native American and Alaskan Natives the least likely to have a pain score recorded. Among patients with a high pain score, patients from racial and ethnic minority groups were also significantly less likely to receive opioid or ketamine analgesia treatment, with Black patients having the lowest adjusted odds of receiving these treatments.
Racial misinformation : how Americans misperceive racial inequality
Keywords: Humanities and Sciences.
Political Science.

Racial inequality has been a fact of American life for as long as the country has existed, but as stubborn as it is, many Americans remain unaware of its pervasiveness. I find strong evidence that, across a host of issues, survey respondents underestimate racial inequality due to limited awareness of the conditions of white and black life in America. These misperceptions of inequality appear to be sincere. I find no evidence of expressive reporting in response to questions about the degree of racial inequality, although this could also be due to the political salience of these issues. If Americans' tendency to underestimate racial inequality is the result of poor information, it seems plausible that providing better information would cause them to be more supportive of racially liberal policies. Consistent with prior research, I find the opposite to be the case: in response to an informational intervention that increases their perception of the degree of racial economic inequality, respondents express substantially more conservative preferences over racial policy. Similarly, using historical data from the General Social Survey and administrative records, I find that when racial inequality rises, many Americans estimate lower levels of racial inequality and express more conservative preferences over racial policy. Among white Americans, this "racial boomerang effect" is driven by a subgroup of respondents who believe that racial inequality is the result of structural forces such as discrimination, but who are resistant to employing structural solutions to address racial inequality. In response to an informational intervention that increases their perception of the degree of racial inequality, these "conflicted structuralists," who experience cognitive distress because their attributions of racial inequality and preferred responses to racial inequality are at odds, and who ultimately resolve this cognitive distress in favor of less egalitarian policies, exhibit a shift towards conservative preferences over racial policy that is larger than the difference in level of support for conservative racial policies between white and black respondents.