Physical Sciences and Mathematics Commons^™

Nonparametric Bayesian Quantile Regression Via Dirichlet Process Mixture Models, Chao Chang

Arts & Sciences Electronic Theses and Dissertations

We propose new nonparametric Bayesian approaches to quantile regression using

Dirichlet process mixture (DPM) models. All the existing quantile regression methods

based on DPMs require the kernel density to satisfy the quantile constraint, hence the

kernel densities are themselves usually in the form of mixtures. One innovation of our

approaches is that we impose no constraint on the kernel, thus a wide range of densities

can be chosen as the kernels of the DPM model. The quantile constraint is satisfied by a

post-processing of the DPM by a suitable location shift. As a result, our proposed models

use simpler kernels …

Photometric Investigations Of Lunar Landing Sites And Silicic Regions Using Lro Narrow Angle Camera Images, Ryan Nicole Watkins

Arts & Sciences Electronic Theses and Dissertations

The reflectance properties of a planetary surface are related to the physical and compositional properties of that body. Photometry is a powerful method for determining differences in composition and regolith structure, and photometric data from orbital images coupled with soil sample data can greatly enhance our understanding of the regolith properties of our nearest neighbor, the Moon. At the time of writing, the United States has no operating missions on the Moon and no future plans to send robots or humans to study our nearest neighbor, so we must rely on remote sensing data to provide us with information about …

Wavelet Factorization And Related Polynomials, David Meyer

Arts & Sciences Electronic Theses and Dissertations

Our goal is exploring and better understanding factorizations of polyphase matrices for finite impulse response (FIR) filters. In particular, we focus on nearest neighbor factorizations discussed by Wickerhauser and Zhu that allow for efficient implementation of the discrete wavelet transform (DWT) for the algorithms of Daubechies and Sweldens and Mallat. Nearest neighbor lifting is a specific form of the general lifting scheme that improves the lifting algorithm by optimizing the number of efficient memory accesses. Nearest neighbor lifting factorizations are typically generated by implementing the Euclidean algorithm for Laurent polynomials, which introduces multiple choices of factorizations of a polyphase matrix …

Kinetic Analysis And Inhibition Studies Of Iron-Dependent Histone Demethylases, Barbara Gordon Cascella

Arts & Sciences Electronic Theses and Dissertations

The research presented herein focuses on the kinetics and inhibition of the KDM4 subfamily of Jumonji C (JmjC) domain-containing histone demethylases (HDMs). Belonging to the larger class of alpha-ketoglutarate (alpha-KG)-dependent, non-heme iron monooxygenases, the JmjC-HDMs remove methyl groups from mono-, di-, and tri-methylated histone lysine residues through an Fe(IV)-oxo-catalyzed hydroxylation reaction. JmjC-HDMs have been found to play integral roles in the maintenance of genomic integrity as well as in the regulation of transcription. Three KDM4 members were studied: the mixed H3K9/H3K36 demethylases KDM4A and KDM4C, and the pure H3K9 demethylase KDM4E. KDM4C is a hypoxia-inducible factor 1 (HIF-1) target gene …

Zinc And Copper Isotopic Fractionation During Planetary Differentiation, Heng Chen

Arts & Sciences Electronic Theses and Dissertations

Zinc and copper are two important transition metal elements that are widely involved in every stage of planetary formation and differentiation. Their isotopic ratios are robust tracers used to understand the origin of the Solar System, planetary formation and differentiation processes. In this thesis, I focus on their isotopic behaviors during magmatic processes. I report the Zn isotopic compositions of representative igneous rocks to determine potential isotopic fractionations associated with magmatic processes, and to estimate the bulk silicate Earth value. I report isotopic compositions of various groups of iron meteorites (samples of which represent the core of asteroids) and discuss …

Isotope Harvesting At Heavy-Ion Fragmentation Facilities, Tara Elise Mastren

Arts & Sciences Electronic Theses and Dissertations

Isotope harvesting from heavy-ion fragmentation facilities is a potential source of isotopes of interest for applications research. With the upgrade of the National Superconducting Cyclotron Laboratory (NSCL) to the Facility for Rare Isotope Beams (FRIB) usable quantities of many isotopes of interest will be produced and available for harvest from an aqueous beam dump. If available, these isotopes would be of interest to a broad range of applications such as medicine, geology, and stockpile stewardship. Preliminary experiments were performed at the NSCL in order to determine the feasibility of isotope harvesting at (FRIB).

A water target station that consisted of …

The Late Ordovician Biogeochemical Carbon Cycle, John Garrecht Metzger

Arts & Sciences Electronic Theses and Dissertations

The isotopic composition of the carbonate carbon (δ13Ccarb) is one of the best tools for understanding the biogeochemical carbon cycle through Earth history. δ13Ccarb is also used to chemostratigraphically correlate coeval strata. This dissertation has three main foci that all utilize δ13Ccarb as the common data type. The geologic interval investigated was the Late Ordovician (458-444 Ma) with emphasis on the Guttenberg δ13C excursion, a globally correlated, positive ~3 / event that is ~400 kyr in duration. In the first topic we evaluate post-depositional alteration (i.e., diagenesis) of δ13Ccarb signals. In the second topic, we make reconstructions of sea level …

Synthesis And Characterization Of Pbs Quantum Sheets Through Lamellar Assembly, And Updates To The Cdse Quantum Wire Synthesis, Paul James Morrison

Arts & Sciences Electronic Theses and Dissertations

This dissertation reports the novel synthesis of PbS quantum plates (QPs) via a reaction executed at low temperatures. The PbS QPs are grown in a template-assisted mechanism, with the first excitonic peak observed in the visible region of light at ~620 nm (2.0 eV), at an energy radically different than the band gap of bulk PbS (~3000 nm, 0.42eV). The large energy shift is due to the extremely thin dimension of these nanoplates, which is determined to be ~1 nm in thickness. Thickness measurements are made in a powder X-ray diffractometer (XRD) at low angles (between 2-15º 2θ). These measurements …

Study Of Ii-Vi Colloidal Semiconductor Magic-Size Nanoclusters And Crystalline Quantum Platelets, Yuanyuan Wang

Arts & Sciences Electronic Theses and Dissertations

The main objective of this project is to prepare and isolate the smallest, discrete, magic-size nanoclusters of cadmium selenide (CdSe) and to grow crystalline, wurtzite CdSe quantum platelets (QPs) at room temperature. The achievement of these goals enables us to provide a general synthesis of II-VI semiconductor magic-size nanoclusters and low-temperature routes to well-passivated nanocrystals having a range of compositions and morphologies.

The magic-size nanocluster (CdSe)13 is grown in a lamellar-bilayer soft template at room temperature. The results described in this thesis strongly suggest that [(CdSe)13(n-octylamine)13] is the most thermodynamically stable nanocluster and serves as a key intermediate in the …

Polyol Synthesis Of Silver Nanowires By Heterogeneous Nucleation And Mechanistic Aspects Influencing Its Length And Diameter, Waynie M. Schuette

Arts & Sciences Electronic Theses and Dissertations

Various additives are employed in the polyol synthesis of silver nanowires (Ag NWs), which are typically halide salts such as NaCl. A variety of mechanistic roles have been suggested for these additives. My research showed that the early addition of NaCl in the polyol synthesis of Ag NWs from AgNO3 in ethylene glycol results in the rapid formation of AgCl nanocubes, which induce the heterogeneous nucleation of metallic Ag upon their surfaces. Ag NWs subsequently grow from these nucleation sites. The conclusions are supported by studies using ex-situ generated AgCl nanocubes.

Additionally, the final mean silver nanowire diameter is found …

Applications Of Nonlinear Optimization, Yao Xie

Arts & Sciences Electronic Theses and Dissertations

We apply an interior point algorithm to two nonlinear optimization problems and achieve improved results. We also devise an approximate convex functional alternative for use in one of the problems and estimate its accuracy.

The first problem is maximum variance unfolding in machine learning. The traditional method to solve this problem is to convert it to a semi-definite optimization problem by defining a kernel matrix. We obtain better unfolding and higher speeds with the interior point algorithm on the original non-convex problem for data with less than 10,000 points.

The second problem is a multi-objective dose optimization for intensity modulated …

Tuning Electronic Correlation With Pressure, Gilberto Fernandes Lopes Fabbris

Arts & Sciences Electronic Theses and Dissertations

Strongly correlated electron systems display some of the most exotic ground states in condensed matter. In this thesis high pressure is used to tune the degree of electron correlations in systems of current interest. Their electronic and structural properties were investigated at high pressure using x-ray spectroscopy and scattering as well as transport techniques in a diamond anvil cell. The interplay between short- and long-range structural order, one-dimensional charge ordering, and superconductivity was studied in La_1.875Ba_0.125CuO₄. At ambient pressure, this material displays charge ordering at the onset of a low temperature structural phase transition, …

Comparison Of Conventional And Bayesian Analysis For The Ultrasonic Characterization Of Cancellous Bone, Amber Groopman

Arts & Sciences Electronic Theses and Dissertations

This dissertation investigates the physics underlying the propagation of ultrasonic waves in cancellous bone. Although quantitative ultrasound has the potential to evaluate bone quality even better than the current gold standard X-ray based modality, its clinical utility has been hampered by the incomplete understanding of the mechanisms governing the interaction between ultrasound and bone. Therefore, studies that extend the understanding of the fundamental physics of the relationship between ultrasound and trabecular bone tissue may result in improved clinical capabilities.

Ultrasonic measurements were carried out on excised human calcaneal specimens in order to study the effects of overlapping fast and slow …

X-Ray Polarimetry With X-Calibur, Qingzhen Guo

Arts & Sciences Electronic Theses and Dissertations

ABSTRACT

X-Ray Polarimetry with X-Calibur

by

Qingzhen Guo

Doctor of Philosophy in Physics, Washington University in St. Louis,

September, 2014. Professor Henric Krawczynski, Chair

X-ray polarimetry is a prime tool to investigate the unexplored compact sources and to provide crucial information that other techniques can not produce. By measuring the degree and orientation of the polarization of radiation from a cosmic source, unique inferences about the morphology and the magnetic field structure can be made.

Krawczysnki's group at Washington University is working on a uniquely sensitive scattering polarimeter, X-Calibur, to be used in the focal plane of a focusing X-ray …

The Impacts Of Climate Change On The World’S Economic, Political, And Demographic Structures, Dino Kanlic

Arts & Sciences Electronic Theses and Dissertations

Climate change will have negative impacts on the political, economic, and demographic structures of society. These include a rise in ethnic tensions in the Indian Sub Continent, massive immigration to Europe, regional economic collapse and political destabilization in Africa, the inundation of island nations and economic losses in the Americas among many other changes which will combine to destabilize humanity for generations. International affairs has failed to come up with a solution because global warming is a universal prevention focused problem that trades short term gains for long term losses. Global warming will be solved by the onset of grid …

Structural And Functional Study Of The Diheme Cytochrome C Subunit Of The Cytochrome Bc Complex In Heliobacterium Modesticaldum, Hair Yue

Arts & Sciences Electronic Theses and Dissertations

This dissertation is focused on the structural and functional study of the unique diheme cytochrome c subunit of the cytochrome bc complex in H. modesticaldum, and its application in determining the stoichiometry between H. modesticaldum's cytochrome bc complex and its reaction center. Heliobacterium modesticaldum is a gram positive, anaerobic, anoxygenic photoheterotrophic bacterium. Its cytochrome bc complex (Rieske/cyt b complex) has some similarities to cytochrome b6f complexes from cyanobacteria and chloroplasts, and also shares some characteristics of typical bacterial cytochrome bc1 complexes. One of the unique features of the heliobacterial cytochrome bc complex is the presence of a diheme cytochrome c …

Photosynthetic Chromophore Analogs And Biohybrid Antenna For Light Harvesting, Joseph William Springer

Arts & Sciences Electronic Theses and Dissertations

Photosynthetic chromophore analogs are studied, starting with simplified structures and systematically building complexity to elucidate overarching design principles. The general goals are to achieve an artificial light-harvesting system that exhibits broad spectral coverage, including extension well into the photon rich red and near-infrared portions of the solar spectrum. For example, the spectral properties of chlorophylls are primarily a consequence of the 13¹-oxophorbine base macrocycle, with further tuning provided by the dramatic difference in auxochromic effects of a given substituent at the 7- versus 3-position, consistent with Gouterman's four-orbital model.

While light-harvesting antennas in photosynthetic bacteria generally have near-quantitative …

A Study On The Structure And Photodetachment Dynamics Of Copper Based Molecular Anions Using Photoelectron Spectroscopy, Nicholas Stephen Holtgrewe

Arts & Sciences Electronic Theses and Dissertations

This dissertation represents a study of the effects of electron molecule interactions in the detachment and dissociation dynamics of copper based molecular anions. Results are presented on the photodetachment of small copper oxide CuO_n⁻ (n = 1, 2) and copper fluoride CuF _n⁻ (n = 1, 2) molecular anions. Effects of different resonances are explored using the photoelectron angular distributions (PADs) and the relative intensity variations in vibrational channel cross sections. The specific resonances studied include dipole bound resonances, in which the electric dipole moment of the neutral molecule captures the outgoing electron, and electronic Feshbach resonances, …

Various Geometric Aspects Of Condensed Matter Physics, Zhenyu Zhou

Arts & Sciences Electronic Theses and Dissertations

Geometric aspect of condensed matter has arouse a lot of interests in recent years. The idea of Berry phase is highly appreciated in various systems. We explored the geometric features of two specific electron systems, fractional quantum Hall (FQH) states and d-wave superconducting states. For FQH states, we propose a two body operator which generates the geometric change of Laughlin state in the guiding center degrees of freedom on torus. This operator therefore generates the adiabatic evolution between Laughlin states on regular tori and the quasi-one-dimensional thin torus limit. For d-wave superconducting model, we study the local and topological features …

Biological Applications Of Extraordinary Electroconductance And Photovoltaic Effects In Inverse Extraordinary Optoconductance, Lauren C. Tran

Arts & Sciences Electronic Theses and Dissertations

The Extraordinary Electroconductance (EEC) sensor has been previously demonstrated to have an electric field sensitivity of 3.05V/cm in a mesoscopic-scale structure fabricated at the center of a parallel plate capacitor. In this thesis, we demonstrate the first successful application of EEC sensors as electrochemical detectors of protein binding and biological molecule concentration. Using the avidin derivative, captavidin, in complex with the vitamin biotin, the change in four-point measured resistance with fluid protein concentration of bare EEC sensors was shown to increase by a factor of four in the presence of biomolecular binding as compared to baseline. Calculations for approximate field …

Assessing Optic Neuritis In A Mouse Model Of Multiple Sclerosis With Diffusion Mr Imaging, Chia-Wen Chiang

Arts & Sciences Electronic Theses and Dissertations

Optic neuritis (ON) is an early manifestation in patients of multiple sclerosis (MS), typically resulting in visual dysfunction. The inflammatory demyelination of the optic nerve in ON closely resembles pathologies of the rest of central nervous system (CNS) white matter in MS. Since accumulated axonal degeneration in MS was considered as the potential cause leading to permanent disability, correlating optic nerve pathology and visual function in ON could be a model system to investigate the relationship between functional outcome and neuropathology. It may also present a new way to reflect the disease progression in MS. Various MR techniques have been …

Effective 1d Language For Fractional Quantum Hall States, John Flavin

Arts & Sciences Electronic Theses and Dissertations

In the theory of the fractional quantum Hall effect, much attention is paid to the correspondence between fractional quantum Hall wave functions and conformal blocks in certain rational conformal field theories (CFT). This correspondence is powerful, enabling the calculation of the fractional statistics of a state that would be difficult if not impossible to calculate directly from the wave functions. But it is, in general, conjectural, remaining without microscopic justification in many cases of interest, and involves heavy mathematical machinery. We detail an alternative method to calculate Abelian and non-Abelian fractional statistics, the coherent state method. The method relies on …

Functional, Degradable Polyester Materials Synthesized From Poly(Epsilon-Caprolactone-Co-2-Oxepane-1,5-Dione): An Investigation Into The Derivatization, Self Assembly, And Degradation Behavior Of Poly(Epsilon-Caprolactone)-Based Materials, Rhiannon K. Iha

Arts & Sciences Electronic Theses and Dissertations

Biocompatible, degradable polymers possessing a high degree of complexity are an extremely desirable target for many applications. In order to further develop the range and utility of materials made from aliphatic polyesters, poly(epsilon-caprolactone-co-2-oxepane-1,5-dione) (P(CL-co-OPD)) was used as a polymeric precursor for the construction of a series of functional polyester-based materials. By taking advantage of the electrophilic ketone moieties characteristic of the OPD repeat unit, small molecule and polymer grafts were attached to the PCL backbone through the formation of both hydrazone and ketoxime ether linkages. This work has focused on both the synthesis and characterization of functional, degradable polyesters, including …

Hardy And Lipschitz Spaces On Unit Spheres, Leonardo Colzani

Arts & Sciences Electronic Theses and Dissertations

The main objective of this work is to develop a theory of Hardy spaces on the surface (SIGMA)(,N) of the unit ball B(,N+1) in (//R)('N+1), analogous to the maximal and atomic theory of Hardy spaces on (//R)('N), and to characterize the duals of these spaces as spaces of Lipschitz functions.