2,412 Works

Neural and Computational Representations of Decision Variables

Daniel Ciarán McNamee
These studies explore how, where, and when representations of variables critical to decision-making are represented in the brain. In order to produce a decision, humans must first determine the relevant stimuli, actions, and possible outcomes before applying an algorithm that will select an action from those available. When choosing amongst alternative stimuli, the framework of value-based decision-making proposes that values are assigned to the stimuli and that these values are then compared in an abstract...

A Report on the Geology of a Portion of the Whittier Hills, Southern California

Stanley William Lohman
The area described in this report occupies a block of approximately 20 square miles, the northwest corner of which is 10 miles east of the center of Los Angeles. (See Figure 1) The southwest corner of the area is occupied by the city of Whittier. The area is situated at the intersection of four quadrangles, including the southeast corner of the El Monte Quadrangle, the southwest corner of the Puente Quadrangle, the northwest corner of...

Fuels and Materials from Sunlight and Water

Bryan Michael Hunter
The urgency to develop new technologies that harness energy and natural feedstocks in a sustainable fashion has never been more apparent. With global power consumption growing at an exponential rate, only one resource is truly capable of powering the planet: the sun. Sunlight is reliable, clean, and free. Significant resources have been pledged to develop and refine solar energy devices that convert photons into electricity (i.e. photovoltaics), but the sun’s intermittency and the poor overlap...

Structural Studies in the Whipple Mountains, Southeastern California

Luis Emmett Kemnitzer
The rocks of the Whipple Mountains include a basement complex of pre-Cambrian age overlain by middle Tertiary volcanics and sedimentary. These are unconformably overlain by flat-lying Pleistocene and recent beds. The broad structural feature of the mountains is a faulted dome, elongated roughly east-west. The dome is out lined on the north and northeast flanks by an arcuate fault which dips away from the mountains. The northeast area of the mountains is broken into southwest-tilted...

Device Architecture for Improved Redox Couple Mass Transport in Silicon Microwire Photoelectrodes and Electrical Contacts to Silicon Microwire Photovoltaics

Andrew Chengsi Meng
Applications of silicon microwires to solar energy conversion are investigated in this thesis, which is divided into two chapters. In the first chapter, silicon microwires are investigated as photoelectrodes in photoelectrochemical cells. The mass transport limitations of redox couple is studied in these liquid junction solar cells, and a device architecture proposed and successfully demonstrated to improve device performance. This work was recently published in the Proceedings of the National Academy of Sciences and is...

Controls on the Sulfur Isotopic Composition of Carbonate-Associated Sulfate

Theodore Michael Present
Sulfate in the modern ocean has a homogenous concentration and sulfur isotopic composition. It is well-mixed because rivers and mantle degassing deliver small amounts relative to its mass in the ocean. A similar small amount of sulfate is removed as biologic, sedimentary, and hydrothermal processes oxidize and reduce sulfur, carbon, and iron. These sulfur fluxes may have changed along with the carbon and oxygen cycles during ancient evolutionary, extinction, climatic, and tectonic transitions. The changing...

Terahertz Time Domain Spectroscopy of Amino Acids and Sugars

Matthew James Kelley
A time-domain spectrometer for use in the terahertz (THz) spectral range was designed and constructed. Due to there being few existing methods of generating and detecting THz radiation, the spectrometer is expected to have vast applications to solid, liquid, and gas phase samples. In particular, knowledge of complex organic chemistry and chemical abundances in the interstellar medium (ISM) can be obtained when compared to astronomical data. The THz spectral region is of particular interest due...

Aerodynamics of Vertical-axis Wind Turbines in Full-scale and Laboratory-scale Experiments

Daniel Borsodi Araya
Within a wind farm, multiple turbine wakes can interact and have a substantial effect on the overall power production. This makes an understanding of the wake recovery process critically important to optimizing wind farm efficiency. Vertical-axis wind turbines (VAWTs) exhibit features that are amenable to dramatically improving this efficiency. However, the physics of the flow around VAWTs is not well understood, especially as it pertains to wake interactions, and it is the goal of this...

Plasma oscillations and radio noise from the disturbed sun. A field analysis of the M type backward wave oscillator

Roy Walter Gould
I. Plasma Oscillations and Radio Noise from the Disturbed Sun. Many investigators have suggested that plasma oscillations in the solar corona may be the source of large bursts of radio noise in the meter wavelength region. Two aspects of this problem are considered in this report: (a) the excitation of plasma oscillations by directed beams of charged particles, and (b) the conversion of energy in the longitudinal plasma oscillations to transverse electromagnetic waves by means...

Spectral Exterior Calculus and Its Implementation

Dzhelil Sabahatin Rufat
Preserving geometric, topological and algebraic structures at play in partial differential equations has proven to be a fruitful guiding principle for computational methods in a variety of scientific fields. However, structure-preserving numerical methods have traditionally used spaces of piecewise polynomial basis functions with local support to interpolate differential forms. When solutions are known to be smooth, a spectral treatment is often preferred instead as it brings exponential convergence. While recent works have established spectral variants...

Nuclear Scattering of High Velocity Electrons. Part I: Nuclear Scattering of High Velocity Electrons. Part II: Reflection of Electrons from Solid Surfaces

Henry Victor Neher
Part I. The results reported in this thesis may be summarized as follows: 1. Nuclear scattering by thin foils has been extended from 80,000 to 145,000 volts. 2. A more critical criterion for single scattering by thin foils is obtained which depends on the shape of the curve connecting ρ, the amount of scattering, with the angle. 3. Secondary electrons are eliminated by applying high equivalent stopping potentials. 4. Dependence of scattering on energy of...

Stable and Radiogenic Isotope Studies of Iron-oxides as Paleoenvironmental and Tectonic Archives

Hayden Bryce Dutcher Miller
Geochemical records of continental weathering environments are limited despite their critical value to understanding how past climates functioned. This thesis seeks to address this limitation by drawing together innovative lines of research in geochronology, stable isotope geochemistry, and chemical weathering. Two distinct projects are described; each project designed to provide new insight into the paleoenvironmental and tectonic history of continental weathering environments. These projects, though distinct in their methods and samples, are unified by their...

Self-Gluing Formula of the Monopole Invariant and its Application on Symplectic Structures

Gahye Jeong
Seiberg-Witten theory has been an important tool in studying a class of 4-manifolds. Moreover, the Seiberg-Witten invariants have been used to compute for simple structures of symplectic manifolds. The normal connected sum operation on 4- manifolds has been used to construct 4-manifolds. In this thesis, we demonstrate how to compute the Seiberg-Witten invariant of 4-manifolds obtained from the normal connected sum operation. In addition, we introduce the application of the formula on the existence of...

Prototyping Diverse Synthetic Biological Circuits in a Cell-Free Transcription-Translation System

Shaobin Guo
Synthetic biological circuits are the foundation for the ultimate goals of controlling cells and building artificial cells from the ground up. To get closer to these goals in a more efficient way, we utilize a cell-free transcription-translation system to help perfect biological circuits for the simplicity, freedom, and convenience that the system offers. In this thesis, we demonstrate three distinct aspects of biological circuits in a cell-free transcription-translation system: circuit dynamics, phosphorylation, and membrane proteins....

How Single Cells Sense Smad3 Signal

Christopher Lee Frick
Animal cells possess the remarkable ability to send, receive, and respond to molecular signals. Accurate processing of these signals is essential for the development and maintenance of complex cell fates and organization. The regulation of cell behavior in response to signal is mediated by signal transduction pathways, which are highly conserved protein-protein interaction networks. Recent work has shown that the activation of biomolecular networks is highly sensitive to natural cellular variation in protein levels, making...

Towards High Performance Robotic Actuation

Nikola-Zlatkov Georgiev
The main objective of this thesis is to enable development of high performance actuation for legged, limbed and mobile robots. Due to the fact that such robots need to support their own weight, their actuators need to be light weight, compact and efficient. Furthermore, a dynamics analysis, shows that the actuators' design may have significant impact on a robot's dynamics sensitivity. These consideration motivate improvements in all actuator design aspects. First, the application-specific design of...

Characterization of Adaptor Binding and Substrate Processing by VCP/p97

Emily E. Blythe
Valosin-containing protein (VCP/p97) is an essential AAA+ ATPase that is critical to numerous important cellular pathways, such as ER-associated degradation. p97 works in concert with a repertoire of adaptor proteins to extract ubiquitylated proteins from membranes or complexes and, often, target them for degradation by the protesome. The nature of the p97 system—dependent upon a complex network of accessory proteins and targeted to substrates that are unstable and heterogeneous—makes the mechanism of substrate processing challenging...

Applications of the Enantioselective Allylic Alkylation Toward the Synthesis of Complex Natural Products

Steven Anthony Loskot
The Stoltz group, and moreover the synthetic community at large, has long been interested in the development of methods for the synthesis of enantioenriched all-carbon quaternary stereocenters. This thesis present three projects all unified by the development and use of the palladium-catalyzed decarboxylative allylic alkylation to synthesize enantioenriched all-carbon quaternary stereocenter containing cyclopentanones as well as the natural product total synthesis.

Statistical Methods for Gene Differential Expression Analysis of RNA-Sequencing

Lynn Yi
RNA-Sequencing ("RNA-Seq") is performed to measure gene expression, often to ask the question of what genes are differentially expressed across various biological conditions. Statistical methods have been used to model RNA-Seq quantifications in order to determine differential expression, and have traditionally be divided into gene-level methods and transcript-level methods. There has been little attempt to connect the statistical divide, although transcript expression and gene expression are biologically inextricably linked. In this thesis, we provide a...

Probing the Roles of Receptor Structure, Drug-Receptor Interactions, and Receptor Crosstalk in Ligand-Gated Ion Channel Function

Walrati Limapichat
Ligand-gated ion channels are multi-subunit transmembrane proteins that play crucial roles in synaptic transmission in the nervous system. These include the Cys-loop receptor superfamily, the ionotropic glutamate receptor (iGluR) family, and the purinergic P2X receptor family. Binding of specific neurotransmitters at the ligand-binding site triggers a series of conformational changes that ultimately leads to ion channel opening. This dissertation describes three molecular-scale functional studies on these receptors. The first project (Chapter 2) describes structure-function studies...

Earth-Abundant Zinc-IV-Nitride Semiconductors

Naomi Cristina Coronel
This investigation is motivated by the need for new visible frequency direct bandgap semiconductor materials that are abundant and low-cost to meet the increasing demand for optoelectronic devices in applications such as solid state lighting and solar energy conversion. Proposed here is the utilization of zinc-IV-nitride materials, where group IV elements include silicon, germanium, and tin, as earth-abundant alternatives to the more common III-nitrides in optoelectronic devices. These compound semiconductors were synthesized under optimized conditions...

Copper Carbazolides in Photoinduced C–N Couplings

Jun Myun Ahn
Photoinduced, copper-catalyzed reactions of organohalides have emerged in recent years as a powerful tool to construct a wide array of C–N bonds, which are prevalent in organic materials and polymers, pharmaceuticals, natural products, and ligands in transition metal catalysts. Described herein is the study and applications of copper complexes ligated by carbazole and its derivatives in photoinduced, copper-catalyzed C–N bond-constructing transformations. Various areas of synthetic inorganic and organic chemistry are explored, including in-depth mechanistic elucidation,...

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