231 Works

New Methods for the Study of Intramolecular and Solvent Dynamics

Aseem Mehta
Some of the fastest processes of relevance to chemical physicists occur on pico to femtosecond timescales. In the following chapters two of such fast processes axe investigated with novel theoretical methods to obtain insight into experimental observations at the molecular level. One of the major topics of interest in chemical physics has been about energy localization in polyatomic molecules. The "golden rule" formula states that the rate for the intramolecular relaxation of energy (IVR) that...

Controlling the Female Body: Obsession and Loss of Autonomy in Lolita and \"Berenice\"

Margaret Lee
[Introduction] Why are we so obsessed with the female body? From high school dress codes to impossible beauty standards in the media, society polices and sexualizes young women's bodies. Nabokov's Lolita, which follows the charming Humbert Humbert and his horrifying relationship with adolescent Lolita, explores this hyperfixation of female bodies, particularly young female bodies. Edgar Allan Poe clearly inspires Nabokov, from the confusing foreward, reminiscent of Poe's novel, The Narrative of Arthur Gordon Pym of...

The Chemistry of Europa and Venus, and Characterization of Earth-like Exoplanets

Jiazheng Li
This thesis contains three parts of work, including oxidant sources on Europa, sulfur chemistry on Venus, and the characterization of Earth-like exoplanets. In the first part, we build two chemical-transport models to study the various oxidant-generation processes that occur in both Europa’s atmosphere and surface ice. The atmospheric model focuses on the role that water plumes play in the formation of Europa’s ionosphere. The simulation results, which show that the ionization reactions are initiated by...

From Building Blocks to Theories: EFThedron and a Haagerup TFT

Tzu-Chen Huang
This thesis is dedicated to the study of certain building blocks of scattering amplitudes in (3+1)d Minkowskian spacetime and that of topological field theory in (1+1)d, together with the constraints which result from the properties of these building blocks. The first part of the thesis is concerned with the introduction of an on-shell formalism for massless and massive particles. We identify all possible three-point tensor structures compatible with the little group symmetry and overall mass...

Strategies and Tools for Machine Learning-Assisted Protein Engineering

Bruce James Wittmann
Proteins perform critical roles in a growing list of human-devised applications, and as demands for new applications arise, new proteins must be engineered to meet them. Machine learning-assisted protein engineering (MLPE) has recently arisen as a new philosophy of protein engineering, promising to overcome many of the limitations of existing engineering strategies. Despite its promise, however, as a relatively new approach to protein engineering, MLPE faces many challenges that hinder its routine application. This thesis...

Nonlinear Dynamics and Stability of Viscous Free-Surface Microcapillary Flows in V-Shaped Channels and on Curved Surfaces

Nicholas C. White
The last two decades have brought a revolution in miniaturization of space technology. Thanks to improved microelectronic sensors and MEMS devices, nanosatellites can perform communication and scientific studies previously limited to large satellites, significantly reducing the financial barriers to space access. But development of a reliable, long-running, small-scale propulsion system for orbital maneuvers remains a key challenge. One solution is the microfluidic electrospray propulsion (MEP) thruster under development at NASA's Jet Propulsion Laboratory (JPL). This...

Resolving Earthquake Source Complexities in the Heterogeneous Earth

Zhe Jia
While the commonly used simple assumptions of sources and structures allows useful first-order approximation of earthquakes, they are increasingly insufficient in characterizing the complex earthquake ruptures and the seismic wave propagations. In this thesis, I present studies that address both the source and structural complexities, as well as their interactions, using flexible parameterizations and ideas. For large earthquakes, I develop a subevent inversion framework to determine their spatiotemporal rupture complexities, and applied it to multiple...

Exploring Earth's Core-Mantle Boundary with Multi-Technique Approaches

Vasilije V. Dobrosavljevic
Earth's core-mantle boundary (CMB) is the most extreme interface of the planet's interior. It regulates the flow of heat out of the core and in doing so influences the two internal engines of our dynamic habitable planet: convection in the solid mantle and the magnetic geodynamo in the core. Seismic observations of the CMB have revealed a complex landscape of heterogeneous multi-scale structures that likely play key roles in Earth's internal dynamics and may hold...

Random Quantum Circuits and Their Simulation Complexity: An Analysis With Statistical Mechanics

Alexander M. Dalzell
Random circuit simulation, the task of replicating the output of a randomly chosen noiseless quantum computation, has been proposed as a path toward achieving quantum advantage: it is believed to be easy for quantum devices, but hard for classical ones. This thesis scrutinizes both sides of this belief. On the one hand, we investigate whether the task is classically hard—we find that, in certain non-trivial cases, it can actually be easy, complicating a potential general...

On the Variational Principles of Linear and Nonlinear Resolvent Analysis

Benedikt Barthel
Despite decades of research, the accurate and efficient modeling of turbulent flows remains a challenge. However, one promising avenue of research has been the resolvent analysis framework pioneered by McKeon and Sharma (2010) which interprets the nonlinearity of the Navier-Stokes equations (NSE) as an intrinsic forcing to the linear dynamics. This thesis contributes to the advancement of both the linear and nonlinear aspects of resolvent analysis (RA) based modeling of wall bounded turbulent flows. On...

The Effects of Confinement in Active Matter: the Casimir Effect, Partitioning, and Hindered Diffusion

Camilla Maria Kjeldbjerg
Active matter describes a class of materials for which constituent "particles" convert chemical energy into mechanical motion leading to self-propulsion (swimming). The origins of this swimming motion for both biological and synthetic constituents is a thriving area of research. However, here we focus on the physical properties and mechanics of the active matter systems. We model active particles using the active Brownian particle (ABP) model that is the simplest model that captures the essential physics,...

Charge and Heat Transport in Non-Metallic Crystals Using First-Principles Boltzmann Transport Theory

Peishi Cheng
Phonon-phonon and electron-phonon interactions underlie many fundamental transport properties like thermal conductivity and electrical mobility, and models of these properties provide information about the underlying microscopic interactions present in the materials. Many of these models use the Boltzmann transport equation where the choice of the expression for the collision integral is the most important and challenging aspect since it should capture all of the relevant interactions. In the past the expressions were semi-empirical, but in...

Applications of Genetically Engineered Bacillus subtilis in Biocatalysis and Functional Materials

Yue Hui
Bacillus subtilis is a gram-positive model bacterium that forms endospores as a response to nutrient limitation and other environmental stresses. The B. subtilis spore contains a dehydrated core, where the bacterial genome is safely stored, and multilayer proteinaceous coats, protecting the spore from various physical and chemical insults. Because of the outstanding resilience of the B. subtilis spore, it has attracted increasing interest for application in biotechnology. In this thesis, we demonstrate the utilization of...

Principles of Massively Parallel Sequencing for Engineering and Characterizing Gene Delivery

David Brown
The advent of massively parallel sequencing and synthesis technologies have ushered in a new paradigm of biology, where high throughput screening of billions of nucleid acid molecules and production of libraries of millions of genetic mutants are now routine in labs and clinics. During my Ph.D., I worked to develop data analysis and experimental methods that take advantage of the scale of this data, while making the minimal assumptions necessary for deriving value from their...

Single Neuron Correlates of Learning, Value, and Decision in the Human Brain

Tomas Gallo Aquino
In this thesis, I present several new results on how the human brain performs value-based learning and decision-making, leveraging rare single neuron recordings from epilepsy patients in vmPFC, preSMA, dACC, amygdala, and hippocampus, as well as reinforcement learning models of behavior. With a probabilistic gambling task we determined that human preSMA neurons integrate computational components of stimulus value such as expected values, uncertainty, and novelty, to encode an utility value and, subsequently, decisions themselves. Additionally,...

Interface Optimization for Improved Photovoltaic Devices

Rebecca Denise Glaudell
The wide band gaps and superior conductivity of ZnSₓSe₁₋ₓ semiconductors to amorphous Si suggest an alternative carrier-selective contact in silicon heterojunction solar cells. Electron-selective ZnSₓSe₁₋ₓ front contacts on p-type c-Si solar cells are explored by simulating in Sentaurus TCAD a large design parameter space informed by experimentally determined optoelectronic properties. Comparable performance to experimental and simulated p-SHJ reference devices is shown, with a champion simulated device efficiency of 20.8%. X-ray photoelectron spectroscopy is used to...

Innate Navigation: Magnetic Sensation and Maze Learning

Matthew H. Rosenberg
This thesis aims to advance the understanding of the neurobiology of navigation through the investigation of two topics: magnetic sensation and maze navigation. The central question of this work may be framed as follows: how do animals find their way to key resources that are necessary for survival? Three projects are presented to address this. Chapter II explores a sensory hypothesis that some animals may navigate long distances by directly sensing the earth’s magnetic field....

Mechanism and Function of Nascent Protein Modification in Bacteria

Chien-I Yang
Newly synthesized proteins undergo multiple modifications to ensure proper biogenesis and acquire their functions. N-terminal methionine excision (NME), mediated by the sequential actions of peptide deformylase (PDF) and methionine aminopeptidase (MAP), is an essential and the most prevalent N-terminal protein modification in the bacterial proteome. Despite the extensive studies on enzymatic catalysis, how NME impacts various cellular functions and how the enzymes achieve timing and selectivity under complex cellular conditions have been long-standing puzzles. In...

Automorphic L-Functions, Geometric Invariants, and Dynamics

Alexandre Perozim de Faveri
We address three different problems in analytic number theory. In the first part, we show that the completed L-function of a modular form has Ω(Tδ) simple zeros with imaginary part in [-T, T], for any δ < 2⁄27. This is the first power bound for forms with non-trivial level in this problem, where previously the best result was Ω(log log log T). Along the way, we also improve the corresponding bound in the case of...

Structural Basis of Antibody Recognition of Viruses

Shannon Esswein
The Zika epidemic in 2015-2016 and COVID-19 pandemic in 2019-2021 are the latest reminders of the enormous impact of viruses on the world. Zika, a flavivirus transmitted by mosquitos, can cause severe neurodevelopmental abnormalities including microcephaly in the newborns of the infected mothers. Vaccine design is complicated by concern that elicited antibodies may also recognize other epidemic-causing flaviviruses that share a similar envelope protein, such as dengue virus, West Nile Virus, and yellow fever virus....

New-to-Nature Selective C-H Alkylation Using Engineered Carbene Transferases

Juner Zhang
Synthetic methods to selectively convert C–H bonds, a prevalent motif in organic molecules, into functionalities can significantly accelerate the syntheses and derivatization of molecules. In the past decade, many enzymatic catalysts have emerged as greener, more selective, and more versatile alternatives to small-molecule catalysts for selective C–H functionalization reactions. In nature, enzymes only catalyze a limited set of C–H functionalization reactions that are useful for chemical synthesis, as the overwhelming majority of known C–H functionalization...

A Multi-Disciplinary Approach: How Aqueous Minerals Hold the Key to Understanding the Climate and Habitability of Terrestrial Planets

Eva L. Scheller
Understanding the interplay between geological processes and the climate within the ancient pasts of terrestrial planets holds the key to deciphering what makes terrestrial planets habitable. The climates of both Mars and Earth were drastically different in their ancient pasts. Liquid water once flowed on Mars ~3-4 Ga, creating fluvial valleys and aqueous minerals, until Mars dried out to the desert planet we know today. During the Pleistocene (~ 2.6 Ma – 11.7 ka) and...

Analytical Chemistry Investigations Toward Understanding the Mechanism of Nitrogenase from Azotobacter vinelandii and the Role of the 4Fe-4S Cluster of Dna2 from Saccharomyces cerevisiae

Siobhán Gaustad MacArdle
Iron sulfur clusters are ubiquitous metal cofactors that play a variety of roles in many enzymes important for health and the climate. The bacterial nitrogenase enzyme, which supports the growth of all organisms by converting atmospheric dinitrogen into ammonia, contains three different redox-active iron sulfur clusters that are central to its function. Dna2, found in all eukaryotes, is integral to genome maintenance and coordinates an iron sulfur cluster of unknown function. Many details of the...

Theory of Mathematical Optimization for Delegated Portfolio Management

Zijian Tao
We study the optimization problem of finding closed convex sets Γ ⊆ Rd containing the origin that minimize F(Γ) = ∑i=1k wi | θi/2 - pΓ(θi) | 2, where w1, ..., wk > 0, θ1, ..., θk in Rd are given, and pΓ(θi) are the closest points in Γ to θi, i = 1, ..., k. This problem is motivated by the topic of delegated portfolio management in finance. In Chapter 2, we will explore...

Between Seismic Speed and Glacial Pace: Cryoseismic Observation of Intermediate-Scale Processes at Lemon Creek Glacier, Alaska

Celeste Ritter Labedz
In this thesis, I present three studies in environmental seismology. First, I present an analysis of seismic tremor generated from subglacial water flow during the rapid drainage of an ice-marginal supraglacial lake, collected by an on-ice nodal seismic array. I find that seismic tremor indicates a partial pressurization of the subglacial hydrologic system that was not accompanied by the expected change in glacier surface velocity, suggesting that factors like glacier geometry play a significant role...

Registration Year

  • 2022

Resource Types

  • Text


  • California Institute of Technology