349 Works

Insights into the Mechanism of Asparagine-Linked Glycosylation: Kinetic Studies with Substrates and Inhibitors

Tamara Lynn Hendrickson
Investigations into the mechanism of action of oligosaccharyl transferase (OT), the enzyme that catalyzes the first committed step in the biosynthesis of all asparagine-linked glycoproteins, were conducted. Research focused on kinetic studies with small reactive molecules and tripeptide substrates and inhibitors; these experiments were designed to specifically probe the OT active site. Commercially available chemical modification agents were used to identify a reactive cysteine residue in or near the oligosaccharide binding site. Based on this...

TCCON data from Nicosia, Cyprus (CY), Release GGG2014.R0

C. Petri, M. Vrekoussis, C. Rousogenous, T. Warneke, J. Sciare & J. Notholt
The Total Carbon Column Observing Network (TCCON) is a network of ground-based Fourier Transform Spectrometers that record direct solar absorption spectra of the atmosphere in the near-infrared. From these spectra, accurate and precise column-averaged abundances of atmospheric constituents including CO2, CH4, N2O, HF, CO, H2O, and HDO, are retrieved. This data set contains observations from the TCCON station at Nicosia, Cyprus (CY).

Seismic Waveform Modeling of Natural Hazards and Sharp Structural Boundaries

Voon Hui Lai
Seismic waveform modeling is a powerful tool for seismologists to learn about the Earth’s dynamics, either how a natural hazard evolves with time, or the long-term deformation process governed by fine-scale structures along boundaries inside the Earth. Knowing that the recorded seismograms reflect the cumulative effects of the source, the earth structure, and the instrument response, I carefully study the characters of the seismograms such as the arrival time, amplitude, frequency content, and multipathing, for...

Resistance is Futile: Physical Science, Systems Biology and Single-Cell Analysis to Understanding the Plastic and Heterogeneous Nature of Melanoma and Their Role in Non-Genetic Drug Resistance

Yapeng Su
Melanoma is the most deadly form of skin cancer due to its great metastatic potential. Targeted therapy that inhibits the BRAF-V600E driver mutation has shown impressive initial responses in melanoma patients. However, drug resistance, as the universal phenomenon for any cancer therapy, always limits treatment efficacy and compromises outcomes. As the early-step of resistance development, non-genetic mechanisms enable cancer cells to transition into a drug-resistant state in as early as a few days after drug...

Radiation from an Electric Dipole in an Anisotropic Cold Plasma

Hans H. Kuehl
The general expression for the far-zone dyadic Green's function in an anisotropic medium is presented. The radiation of an electric dipole in a cold plasma is considered. Expressions for the far-zone radiation from a dipole for the case of weak magnetic field and low plasma density are derived. Expressions are also obtained for the case of an infinite magnetic field.

High-Cycle Dynamic Cell Fatigue with Applications on Oncotripsy

Erika Figueroa-Schibber
The method of oncotripsy (from Greek, onco- meaning "tumor" and –tripsy "to break") exploits aberrations in the material properties and morphology of cancerous cells to target them selectively using tuned low-intensity pulsed ultrasound. Compared to other noninvasive ultrasound treatments that ablate malignant tissue, oncotripsy has the capability of targeting unhealthy tissue with minimal damage to healthy cells in the ablation process. We propose a model of oncotripsy that follows as an application of cell dynamics,...

Mechanistic Studies of Alkane Activation by Platinum(II) Complexes

Shannon Scot Stahl
Currently, there is considerable interest in alkane oxidation reactions catalyzed by transition metal complexes. Chapter 1 reviews many of the recent advances in this field involving electrophilic late transition metals. The C-H activation step appears to dictate both the rate and selectivity of these reactions. Unfortunately, however, very little is known about the mechanism of this step. In chapter 2, mechanistic studies of the protonolysis of several alkylplatinum(II) complexes [(tmeda)PtMeCl, (tmeda)Pt(CH2Ph)Cl, (tmeda)PtMe2, and trans(PEt3)2Pt(CH3)Cl] are...

Geological Evolution of Two Crustal Scale Shear Zones: Part I: The Rand Thrust Complex, Northwestern Mojave Desert, California. Part II: The Magdalena Metamorphic Core Complex, North Central Sonora, Mexico

Jonathan Alan Nourse
The geology and structure of two crustal scale shear zones were studied to understand the partitioning of strain within intracontinental orogenic belts. Movement histories and regional tectonic implications are deduced from observational data. The two widely separated study areas bear the imprint of intense Late Mesozoic through Middle Cenozoic tectonic activity. A regional transition from Late Cretaceous-Early Tertiary plutonism, metamorphism, and shortening strain to Middle Tertiary extension and magmatism is preserved in each area, with...

Quantum Correlations, Certifying Quantum Devices, and the Quest for Infinite Entanglement

Andrea Wei Coladangelo
Quantum information has the potential to disrupt the present computational landscape. Much of this potential rests on the existence of efficient quantum algorithms for classically intractable problems and of quantum cryptographic protocols for tasks that are provably impossible to realize classically. At the heart of many quantum advantages is one of the most counterintuitive features of quantum mechanics, known as entanglement. The central motivating question of this thesis is the following: if quantum devices will...

Resonance Cones and Mode Conversion in a Warm Magnetized Bounded Plasma

Crockett Lane Grabbe
The warm plasma resonance cone structure of the quasistatic field produced by a gap source in a bounded magnetized slab plasma is determined theoretically. This is initially determined for a homogeneous or mildly inhomogeneous plasma with source frequency lying between the lower hybrid frequency and the plasma frequency. It is then extended to the complicated case of an inhomogeneous plasma with two internal lower hybrid layers present, which is of interest to radio frequency heating...

LIGO Virgo strain data from GW190412 event

On the Index of Refraction of Spatially Periodic Plasma

C. H. Papas
A knowledge of the change produced in the index of refraction of a uniform plasma by the spontaneous generation of coagula or inhomogeneities is essential to the use of electromagnetic waves as a diagnostic tool. The general problem is a difficult one to handle, but certain non-trivial cases are mathematically tractable. One of these, which is also of some practical import, occurs when the inhomogeneities are periodically distributed throughout the plasma. Here this special case...

Nanophotonic Phenomena in Dielectric Photonic Crystals

Ryan Cecil Ng
Photonic crystals are periodic optical nanostructures with varying dielectric constant that allow light flow to be controlled and manipulated much in a similar way to electrons within a semiconductor crystal. These nanostructures tend to have a spatially varying refractive index on the order of the wavelength of light to be manipulated. 1D and 2D photonic crystals have already garnered significant attention in the realm of thin-film optics, while 3D photonic crystals have been thus far...

Shock Compression of Molybdenum Single Crystals to High Stresses

Tomoyuki Oniyama
To investigate the role of crystal anisotropy and the impact stress on the shock induced elastic-plastic deformation of BCC single crystals at high stresses, molybdenum single crystals were shock compressed along [100], [111], and [110] orientations. A series of plate impact experiments were conducted with various impact stresses (23 - 190 GPa) along each orientation. Along the [100] and [111] orientations, two-wave structure - an elastic shock wave trailed by a plastic shock wave -...

Calibration and Study of the Contoured Nozzle of the T5 Free-Piston Hypervelocity Shock Tunnel

Bernard Rousset
A pitot pressure survey of the contoured nozzle of the T5 shock tunnel was performed over a wide range of reservoir conditions and in the region of the exit plane of the nozzle. A rake of thirteen pitot probes was used for this purpose. The survey includes an investigation of the repeatability of the facility and an analysis of the accuracy of the measurements. The features of the pitot pressure distribution across the exit plane...

Mechanical Characterization of Damage and Failure in Polymeric Foams and Glass/Epoxy Composites

Theresa Hiromi Kidd
The mechanical characterization including evolution of damage and failure of foams and composites are becoming increasingly important, as they form the basic components of sandwich structures. Sandwich structures consist of two faceplates that surround a core material. In many modern applications, faceplates and cores are typically comprised of composite materials and polymeric foam, respectively. Knowledge of the failure behavior of these individual components is necessary for understanding the failure behavior and design of sandwich structures....

Simulations and Analysis of Two- and Three-Dimensional Single-Mode Richtmyer-Meshkov Instability using Weighted Essentially Non-Oscillatory and Vortex Methods

Marco Latini
An incompressible vorticity-streamfunction (VS) method is developed to investigate the single-mode Richtmyer-Meshkov instability in two and three dimensions. The initial vortex sheet (representing the initial shocked interface) is thickened to regularize the limit of classical Lagrangian vortex methods. In the limit of smaller thickness, the initial velocity converges to the velocity of a vortex sheet. The vorticity on the Cartesian grid follows the vorticity evolution equation augmented by the baroclinic vorticity production term (to capture...

Mechanisms of Phenazine-Mediated Extracellular Electron Transfer by Pseudomonas aeruginosa

Scott Harrison Saunders
Extracellular electron transfer (EET), the process whereby cells access electron acceptors or donors that reside many cell lengths away, enables metabolic activity by microorganisms, particularly under oxidant-limited conditions that occur in multicellular bacterial biofilms. Although different mechanisms underpin this process in individual organisms, a potentially widespread strategy involves extracellular electron shuttles, redox-active metabolites that are secreted and recycled by diverse bacteria. Here, I first review general aspects of the electron shuttling strategy, such as the...

Pronouns

Kelly Roach
No abstract.

Force Field Development in Protein Design

Eric Stafford Zollars
Protein design requires the rapid evaluation of very large numbers of equations during the course of a calculation. These equations must represent the important contributors to protein stability in simple and accurate terms. Some physical phenomena are relatively easy to model such as van der Waals forces. Electrostatics and solvation in a protein environment are forces that are more difficult to adequately capture. Additionally, the balance of the terms used must be determined in order...

Expression of the Genes Encoding the Cytoskeletal Proteins Vimentin and Protein 4.1

John J. Ngai
The investigations presented in this thesis represent an effort to understand the regulated expression of cytoskeletal proteins in differentiating cell systems. Vimentin is an intermediate filament protein whose expression is regulated during the differentiation of a variety of cell types. I have isolated DNA probes specific for chicken vimentin and utilized them for the study of vimentin gene regulation. The single chicken vimentin gene encodes multiple mRNAs that differ in the lengths of their 3'...

Ubiquitin-Proteasome System at the Synapse

Baris Bingol
Each neuron in the mammalian central nervous system makes up to ten thousand synaptic connections with other neurons yet is able to regulate the strength of individual connections locally. Synaptic enhancement or depression induced at one location on the dendritic arbor does not spread through out the entire neuron. This means neurons must be able to regulate the complement and concentration of the synaptic proteins locally, near synapses. The local concentration of synaptic proteins is...

Weight Enumerators and Gray Maps of Linear Codes over Rings

Bahattin Yildiz
The main focus in this thesis is linear codes over rings. In the first part, we look at linear codes over Galois rings, and using the homogeneous weight, we improve upon Wilson's results about the prime power that divides the coefficients of the homogeneous weight enumerators of these codes. We also prove that our results are best possible. Our results about homogeneous weight enumerators of linear codes over Galois rings generalize the results that we...

1. Tidal Synchronization of the Rotation of Early Main Sequence Stars in Close Binaries. 2. The Rings of Uranus: Results of the 1978 April 10 Occultation. 3. On the Resonance Theory of the Rings of Uranus

Philip David Nicholson
Part 1: The rotational synchronization of an early type main sequence star in a close binary system has been attributed to radiative damping of the dynamical component of the tide raised in the star by its companion (Zahn, 1975, 1977). An investigation of the dynamical tide is presented here, which includes the heretofore neglected effects of stellar rotation. Foremost among these effects is the splitting of the tidal response into a set of modes whose...

A Model for Stress-Driven Diffusion in Polymers

Robert William Cox
Penetration of solvents into polymers is sometimes characterized by steep concentration gradients that move into the polymer and last for long times. The behavior of these fronts cannot be explained by standard diffusion equations, even with concentration dependent diffusion coefficients. The addition of stress terms to the diffusive flux can produce such progressive fronts. Model equations are proposed that include solvent flux due to stress gradients in addition to the Fickian flux. The stress in...

Registration Year

  • 2020
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  • California Institute of Technology
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