Physical Sciences and Mathematics Commons^™

Polymeric Radiation Shielding For Applications In Space: Polyimide Synthesis And Modeling Of Multi-Layered Polymeric Shields, Clinton Cleveland Schiavone

Dissertations, Theses, and Masters Projects

No abstract provided.

A Tunable Electromagnetic Band-Gap Microstrip Filter, Greg A. Lancaster

Master's Theses

In high frequency design, harmonic suppression is a persistent struggle. Non-linear devices such as switches and amplifiers produce unwanted harmonics which may interfere with other frequency bands. Filtering is a widely accepted solution, however there are various shortcomings involved. Suppressing multiple harmonics, if desired, with traditional lumped element and distributed component band-stop filters requires using multiple filters. These topologies are not easily made tunable either. A new filter topology is investigated called Electromagnetic Band-Gap (EBG) structures.

EBG structures have recently gained the interest of microwave designers due to their periodic nature which prohibits the propagation of certain frequency bands. EBG …

Analysis Of Spark Versus Non-Spark Mediated Sr Calcium Leak Using A Langevin Description Of Stochastic Calcium Release, Xiao Wang, Seth H. Weinberg, Gregory D. Smith, Yan Hao, Eric A. Sobie

Arts & Sciences Articles

No abstract provided.

Unlocking The Secrets Of Al-Tobermorite In Roman Seawater Concrete, Marie D. Jackson, Sejung R. Chae, Sean R. Mulcahy, Cagla Meral, Rae Taylor, Penghui Li, Abdul-Hamid Emwas, Juhyuk Moon, Seyoon Yoon, Gabriele Vola, Hans-Rudolf Wenk, Paulo J.M. Monteiro

Geology Faculty Publications

Ancient Roman syntheses of Al-tobermorite in a 2000-year-old concrete block submerged in the Bay of Pozzuoli (Baianus Sinus), near Naples, have unique aluminum-rich and silica-poor compositions relative to hydrothermal geological occurrences. In relict lime clasts, the crystals have calcium contents that are similar to ideal tobermorite, 33 to 35 wt%, but the low-silica contents, 39 to 40 wt%, reflect Al³⁺ substitution for Si⁴⁺ in Q² (1Al), Q³ (1Al), and Q3 (2 Al) tetrahedral chain and branching sites. The Al-tobermorite has a double silicate chain structure with long chain lengths in the b [020] crystallographic direction, and …

Higher Algebraic K-Theory And Tangent Spaces To Chow Groups, Sen Yang

LSU Doctoral Dissertations

In this work, using higher algebraic K-theory, we provide an answer to the following question asked by Green-Griffiths in [13]: Can one define the Bloch-Gersten-Quillen sequence G_j on infinitesimal neighborhoods X_j so that Ker(G₁ &rarr G₀)= TG₀, Here TG₀ should be the Cousin resolution of TK_m(O_X) and X is any n-dimensional smooth projective variety over a field k, chark=0. Our main results are as follows. The existence of G_j is discussed in chapter 3, following [8] and [18]. The main theorems are theorem5.2.5, theorem 5.2.6 and theorem …

Vibrio Parahaemolyticus Interactions With Chitin In Response To Environmental Factors, Vanessa Molina

LSU Doctoral Dissertations

Vibrio parahaemolyticus is a naturally occurring chitinoclastic human pathogen that adsorbs to substrates, including chitinous copepods and oysters, as part of its ecology, a phenomenon that is important in its responses to changes in environmental factors such as temperature and salinity. Little is known about acute responses of V. parahaemolyticus when subjected to abrupt environmental changes such as those encountered during postharvest oyster treatments such as icing, exposure to mammalian host conditions, and transport via ballast water. The following in vitro studies investigated V. parahaemolyticus adsorption and gene expression as a function of substrate, temperature, and salinity as a model …

Model Sensitivity In Holographic Superconductors And Their Deconstructed Cousins, Joshua X. Erlich, Zhen Wang

Arts & Sciences Articles

Holographic models of superconductors successfully reproduce certain experimental features of high-temperature superconductors, such as a large gap-to-Tc ratio compared to that of conventional superconductors. By deconstructing the extra dimension of these holographic models, similar phenomenology is described by a class of models defined in the natural dimension of the superconducting system. We analyze the sensitivity of certain observables in holographic and deconstructed holographic superconductors to details of the extra-dimensional spacetime. Our results support the notion that certain quantitative successes of simple models of this type are accidental. However, we also find a certain universal relationship between superconducting observables.

Rock Glaciers In The Eastern Cascades, Washington, Mark Weidenaar

Undergraduate Honors Theses

The eastern portion of Washington State's Cascade Range is a place not previously examined for rock glaciers, due to proximity to the Pacific Ocean and its associated marine-influenced climate. The objectives of this study were to determine spatial, activity, and genesis patterns, and paleoclimatic implications of Eastern Cascade rock glaciers. Using Google Earth, I found 103 rock glaciers in the study area. Rock glaciers are more common further east of the Cascade crest and more north in latitude, with the largest concentrations occurring east of Lake Chelan (22) and in the Pasayten Wilderness (28) in the North Cascades. None were …

Effects Of Micro-Solvation On Room Temperature Ionic Liquids, Joseph Wellington Golden

Honors Theses

Room temperature ionic liquids (RTILs) have received much attention lately. These compounds are made completely of ions and are liquid at or near room temperature. These liquid salts have a number of unique properties that make them an interesting system to study. These properties include almost zero vapor pressure, thermal stability, large liquidus range, etc. Due to these properties and others, ionic liquids (ILs) have attracted much attention in the emerging field of green chemistry as potentially new solvents for many of the hazardous and volatile solvents currently in use. Moreover, the complex interactions of the anion and cation systems …

Cross Sections For The Ɣp → K*+Ʌ And Ɣp → K*+Σº Reactions Measured At Clas, K.P. Adhikari, M. J. Amaryan, C. E. Hyde, S. Koirala, M. Mayer, Clas Collaboration

Physics Faculty Publications

The first high-statistics cross sections for the reactions ɣp → K*+Ʌ and ɣp → K*+Σº were measured using the CLAS detector at photon energies between threshold and 3.9 GeV at the Thomas Jefferson National Accelerator Facility. Differential cross sections are presented over the full range of the center-of-mass angles, and then fitted to Legendre polynomials to extract the total cross section. Results for the K*+Ʌ final state are compared with two different calculations in an isobar and a Regge model, respectively. Theoretical calculations significantly underestimate the K*+Ʌ total cross sections between 2.1 and 2.6 GeV, but are in better agreement …

Geometry Effects On Multipole Components And Beam Optics In High-Velocity Multi-Spoke Cavities, C. S. Hopper, K. Deitrick, J. R. Delayen

Physics Faculty Publications

Velocity-of-light, multi-spoke cavities are being proposed to accelerate electrons in a compact light-source [1]. There are strict requirements on the beam quality which require that the linac have only small non-uniformities in the accelerating field. Beam dynamics simulations have uncovered varying levels of focusing and defocusing in the proposed cavities, which is dependent on the geometry of the spoke in the vicinity of the beam path. Here we present results for the influence different spoke geometries have on the multipole components of the accelerating field and how these components, in turn, impact the simulated beam properties.

Comparison Of Electromagnetic, Thermal And Mechanical Calculations With Rf Test Results In Rf Dipole Deflecting/Crabbing Cavities, H. Park, S. U. Silva, J. R. Delayen

Physics Faculty Publications

The current requirements of higher gradients and strict dimensional constraints in the emerging applications have required the designing of compact deflecting and crabbing rf structures. The superconducting rf-dipole cavity is one of the first novel compact designs with attractive properties such as higher gradients, higher shunt impedance and widely separated higher order modes. The recent tests performed on proof-of-principle designs of the rf-dipole geometry at 4.2 K and 2.0 K in a vertical test assembly have proven the designs to achieve higher gradients with higher intrinsic quality factors and easily processed multipacting conditions. The design frequency sensitivity to pressure (df/dp) …

Deep Exclusive Π+ Electroproduction Off The Proton At Clas, K. P. Adhikari, M. J. Amaryan, R. P. Bennett, G. E. Dodge, S. E. Kuhn, M. Mayer, C. S. Nepali, H. Seraydaryan, L. B. Weinstein, J. Zhang

Physics Faculty Publications

The exclusive electroproduction of π ⁺ above the resonance region was studied using the CEBAF Large Acceptance Spectrometer (CLAS) at Jefferson Laboratory by scattering a 6GeV continuous electron beam off a hydrogen target. The large acceptance and good resolution of CLAS, together with the high luminosity, allowed us to measure the cross section for the γ ^* p → nπ ⁺ process in 140 (Q ², x _B , t) bins: 0.16 < x _B < 0.58, 1.6 GeV² < Q ² < 4.5 GeV² and 0.1 GeV² < −t < 5.3 GeV². For most bins, the statistical accuracy is on the order of a …

Compact Superconducting Crabbing And Deflecting Cavities, Subashini De Silva

Physics Faculty Publications

Recently, new geometries for superconducting crabbing and deflecting cavities have been developed that have significantly improved properties over those the standard TM110 cavities. They are smaller, have low surface fields, high shunt impedance and, more importantly for some of them, no lower-order-mode with a well-separated fundamental mode. This talk will present the status of the development of these cavities.

Compact Accelerator Design For A Compton Light Source, Todd Satogata, Kirsten Deitrick, Jean Delayen, B.R.P. Gamage, K. Hernández-Chahín, C. Hopper, Geoffrey Krafft, Rocio Olave

Physics Faculty Publications

A compact electron accelerator suitable for Compton source applications is in design at the Center for Accelerator Science at Old Dominion University and Jefferson Lab. The design includes a KE=1.55 MeV low-emittance, optimized superconducting electron gun; a 23.45 MeV linac with multi-spoke 4.2 K superconducting cavities; and transport that combines magnetic longitudinal bunch compressor and transverse final focus. We report on the initial designs of each element, including end to end simulations with ASTRA and elegant, and expected beam parameters.

Multipole Expansion Of The Fields In Superconducting High-Velocity Spoke Cavities, R. G. Olave, Jean R. Delayen, C. S. Hopper

Physics Faculty Publications

Multi-spokes superconducting cavities in the high-beta regime are being considered for a number of applications. In order to accurately model the dynamics of the particles in such cavities, knowledge of the fields off-axis are needed. We present a study of the multipoles expansion of the fields from an EM simulation field data for two-spokes cavities operating at 325 MHz, β = 0.82, and 500 MHz, β = 1.

Arsenic And Phosphorus Biogeochemistry In The Ocean: Arsenic Species As Proxies For P-Limitation, Oliver Wurl, Louise Zimmer, Gregory A. Cutter

OES Faculty Publications

Arsenic and phosphorus are biochemically very similar, and hence arsenate (As⁵⁺) is toxic by interfering with the energy metabolism, in particular during P limitation. However, many phytoplankton detoxify As by reducing arsenate to arsenite (As³⁺), and/or methylating it to mono and dimethyl As. Such As detoxification becomes operative in oligotrophic waters when phosphate concentrations are below those for As; therefore, we evaluated the potential use of these detoxification products as indicators of P-limitation by measuring As speciation during the US GEOTRACES North Atlantic transect. The distribution of As³⁺ concentrations in surface waters is similar to …

Using Ammonium Pore Water Profiles To Assess Stoichiometry Of Deep Remineralization Processes In Methanogenic Continental Margin Sediments, David J. Burdige, Tomoko Komada

OES Faculty Publications

In many continental margin Sediments, a deep reaction zone exists which is separated from remineralization processes near the sediment surface. Here, methane diffuses upward to a depth where it is oxidized by downwardly diffusing sulfate. However, the methane sources that drive this anaerobic oxidation of methane (AOM) in the sulfate-methane transition zone (SMT) may vary among sites. In particular, these sources can be thought of as either (i) "internal" sources from in situ methanogenesis (regardless of where it occurs in the sediment column) that are ultimately coupled to organic matter deposition and burial, or (ii) "external" sources such as hydrocarbon …

Galaxy Inclination And Surface Brightness, Jordan C. Rozum, Shane L. Larson

Student Showcase

The distribution of spiral and bar galaxy inclination angles is expected to be uniform. However, analysis of several major galaxy catalogs shows this is not the case; galaxies oriented near edge-on are significantly more common in these catalogs. In an attempt to explain this discrepancy, we have developed a galaxy simulation code to compute the appearance of a spiral type galaxy as a function of its morphological parameters. We examine the dependence of observed brightness upon inclination angle by using smooth luminous mass density and interstellar medium (ISM) density distributions. The luminous mass component is integrated along a particular line …

Curds And Whey: Little Miss Muffit's Contribution To Multivariate Linear Regression, John Cameron Kidd

Undergraduate Honors Capstone Projects

A common multivariate statistical problem is the prediction of two or more response variables using two or more predictor variables. The simplest model for this situation is the multivariate linear regression model. The standard least squares estimation for this model involves regressing each response variable separately on all the predictor variables. Breiman and Friedman [1] show how to take advantage of correlations among the response variables to increase the predictive accuracy for each of the response variable with an algorithm they call Curds and Whey. In this report, I describe an implementation of the Curds and Whey algorithm in …

Delineation And Characterization Of The Furnace Brook Watershed In Marshfield, Massachusetts: Potential Impact Of Water Supply Extraction, Erik Croll

Undergraduate Review

The Furnace Brook watershed in Marshfield, Massachusetts supplies a coastal community of 25,132 residents with nearly 45% of its town water supply (Marshfield 2012a). As in many other coastal communities, development pressure in Marshfield has increased in recent years, creating a growing demand for freshwater extraction. It has been observed, however, that portions of the stream and Furnace Pond disappear entirely at certain times of year, generally between June and August, depending on the rate of groundwater extraction. This has created a conflict between protecting the designated wetland areas and meeting public pressure for water resources, even within what is …

The Effect Of Hydrochloric Acid Strength On The Nanometer-Scale Dissolution Topography Of Calcite Crystal Surfaces, Jennifer Fruzzetti

Undergraduate Review

The physico-chemical mechanisms by which rock-forming minerals dissolve in natural fluids are controlled by a number of environmental factors. In this study, we investigate dissolution mechanisms by observing how the nanometer-scale surface topography of calcite is affected by the acidity of etching solutions. Here we report atomic force microscope (AFM) observations of calcite crystal surfaces both before and after chemical etching for 10 seconds in 0.01%, 0.1%, and 1.0% HCl solutions. AFM observations show that unetched, freshly-cleaved calcite {10ī4} crystal surfaces are characterized by flat layers separated by steps oriented parallel to calcite cleavage planes. Calcite {10ī4} crystal surfaces etched …

Exploring Diagonals In The Calkin-Wilf Tree, Matthew Gagne

Undergraduate Review

For centuries, people have been interested in patterns. Even in that which appears random, humans have been trying to understand the underlying order of things. Mathematicians throughout time have studied many phenomena, including infinite sequences of numbers and have been able, at times, to see structure. Many have found the satisfaction, even joy, of discovering patterns in sequences. A typical way to describe this is by a recursive formula. A recursive definition defines a term in the sequence using the previous terms in the sequence. Even more satisfying than a recursive formula is a closed formula. With this, one can …

Modeling Plaque Aggregation On The Neuronal Network, Thomas Howard

Undergraduate Review

Alzheimer’s disease is a condition linked to plaque aggregation in the brain. Despite being the focus of many studies, current treatments are of questionable significance in the overall improvement of a patient’s condition. In recent years, computer models have been used to better understand complex biological systems and simulate the effects of various treatments. In the following paper we present a mathematical model studying the effects of plaque aggregation on the neuronal pathways of the human brain. To create our mathematical model we employ tools from the theory of dynamical systems and stochastic processes, and simulate the passage of a …

Computer Programming To Advance Gravitational Lensing, Alex Roche

Undergraduate Review

The purpose of this research was to create a computer code that would numerically test a Poisson equation relating the mass distribution of a lens galaxy cluster to weak gravitational shear. Einstein’s theory of general relativity predicts that space-time is bent by massive objects, and in weak gravitational lensing, galaxy clusters act as lenses. The observable result is that galaxies far behind the gravitational lens will appear slightly more elliptical than they actually are. The ellipticity of the background galaxies is quantifiable and is directly related to the weak gravitational shear, and the shear is used to determine the mass …

A Greener Disney, Cidalia Pina

Undergraduate Review

Disney brings nature and environmental issues to the forefront with its non-confrontational approach to programming meant for children. This opportunity raises awareness and is relevant to growing environmental concerns. However this awareness is just a cursory start, there is an imbalance in their message and effort with that of their carbon footprint. The important eco-messages that Disney presents are buried in fantasy and unrealistic plots. As an entertainment giant with the world held magically captive, Disney can do more, both in filmmaking and as a corporation, to facilitate a greener planet.

Galaxy Zoo : A Catalog Of Overlapping Galaxy Pairs For Dust Studies., William C. Keel, Anna M. Manning, Benne W. Holwerda, Massimo Mezzoprete, Chris J. Lintott, Kevin Schawinski, Pamela Gay, Karen L. Masters

Faculty Scholarship

Analysis of galaxies with overlapping images offers a direct way to probe the distribution of dust extinction and its effects on the background light. We present a catalog of 1990 such galaxy pairs selected from the Sloan Digital Sky Survey (SDSS) by volunteers of the Galaxy Zoo project. We highlight subsamples which are particularly useful for retrieving such properties of the dust distribution as UV extinction, the extent perpendicular to the disk plane, and extinction in the inner parts of disks. The sample spans wide ranges of morphology and surface brightness, opening up the possibility of using this technique to …

Part Qm: Quantum Mechanics, Konstantin Likharev

Essential Graduate Physics

Includes: Introduction; 1D Wave Mechanics; Higher Dimensionality Effects; Bra-ket Formalism; Some Exactly Solvable Problems; Perturbation Theories; Open Quantum Systems; Multiparticle Systems; Introduction to Relativistic Quantum Mechanics; Making Sense of Quantum Mechanics

References, Appendices & All Parts Merged, Konstantin Likharev

Essential Graduate Physics

Includes: Appendix MA: Selected Mathematical Formulas; Appendix CA: Selected Physical Constants; References; EGP merged file (all parts, appendices, and references)

Black Carbon Measurements Of Snow And Ice Using The Single Particle Soot Photometer: Method Development And An Ad 1852-1999 Record Of Atmospheric Black Carbon From A Mount Logan Ice Core, James Andrew Menking

All Master's Theses

Black carbon (BC), produced by the combustion of fossil and biofuels, warms the climate by absorbing solar radiation when in the atmosphere and by reducing the albedo of snow and ice when deposited. Measuring BC in snow and ice is important for estimating albedo reduction and developing historical records of BC concentration. Experiments were conducted to further develop a method for measuring BC in snow and ice using the Single Particle Soot Photometer (SP2). Results suggest the optimal procedures for sample storage, treatment, and nebulization, and analysis and calibration of BC concentrations measured using the SP2 coupled to a CETAC …