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Observation And Control Of Photoemission And Electric Field Enhancement Of Plasmonic Antennas Through Photoemission Electron Microscopy, Christopher M. Scheffler

Dissertations and Theses

Photoemission electron microscopy (PEEM) is an imaging method which uses electrons excited through the photoelectric effect to characterize a sample surface with nanometer-level resolution. In PEEM, a high intensity laser excites electrons from the surface of the material and electron optics are used to form an image from the intensity and spatial distribution of the photoemission from the sample. The goal of this research was to study and maximize light confinement, which was accomplished using plasmonic nanostructures. Surface plasmons represent oscillations in the electron density of a material and can occur along the transition interface between a metal and a …

Full Pattern Analysis And Comparison Of The Center Fed And Offset Fed Cassegrain Antennas With Large Focal Length To Diameter Ratios For High Power Microwave Transmission, Derek W. Mantzke

Theses and Dissertations

High power microwaves (HPM) have been a topic of research since the Cold War era. This paper will present a comparison between two Cassegrain-type antennas: the axially, or center fed, and the offset fed. Specifically, the 10 GHz operating frequency will be investigated with large focal length to diameter () ratios. Beam patterns which encompass the entire radiation pattern will be included for data validation and optimization. The simulations will follow a design of experiments factorial model to ensure all possible combinations of prescribed parameters are included, including an analysis of variance (ANOVA) study to find parameter influence on the …

Symmetry-Inspired Analysis Of Biological Networks, Ian Leifer

Dissertations, Theses, and Capstone Projects

The description of a complex system like gene regulation of a cell or a brain of an animal in terms of the dynamics of each individual element is an insurmountable task due to the complexity of interactions and the scores of associated parameters. Recent decades brought about the description of these systems that employs network models. In such models the entire system is represented by a graph encapsulating a set of independently functioning objects and their interactions. This creates a level of abstraction that makes the analysis of such large scale system possible. Common practice is to draw conclusions about …

Molecular Beam Epitaxy Of Antiperovskite Oxides, H. Nakamura, H. Takagi, D. Huang

Physics Faculty Publications and Presentations

Antiperovskites, or inverse perovskites, have recently emerged as a material class with a plethora of promising electronic properties. This Perspective describes the molecular beam epitaxy (MBE) growth of oxide antiperovskites Sr₃PbO and Sr₃SnO. We show that MBE offers great potential in regard to not only growing antiperovskites with high structural quality but also providing a means for seamless integration with advanced characterization techniques, including x-ray photoelectron spectroscopy, low-energy electron diffraction, reflection high-energy electron diffraction, and scanning tunneling microscopy, to facilitate the analyses of their intrinsic properties. The initial results point toward the feasibility of atomically controlled …

Artificial Atoms From Cold Bosons In One Dimension, Fabian Brauneis, Timothy G. Backert, Simeon I. Mistakidis, Mikhail Lemeshko, Hans Werner Hammer, Artem G. Volosniev

Physics Faculty Research & Creative Works

We Investigate The Ground-State Properties Of Weakly Repulsive One-Dimensional Bosons In The Presence Of An Attractive Zero-Range Impurity Potential. First, We Derive Mean-Field Solutions To The Problem On A Finite Ring For The Two Asymptotic Cases: (I) All Bosons Are Bound To The Impurity And (Ii) All Bosons Are In A Scattering State. Moreover, We Derive The Critical Line That Separates These Regimes In The Parameter Space. In The Thermodynamic Limit, This Critical Line Determines The Maximum Number Of Bosons That Can Be Bound By The Impurity Potential, Forming An Artificial Atom. Second, We Validate The Mean-Field Results Using The …

Silverrush. Xii. Intensity Mapping For Ly Α Emission Extending Over 100-1000 Comoving Kpc Around Z ∼2-7 Laes With Subaru Hsc-Ssp And Chorus Data, Shotaro Kikuchihara, Yuichi Harikane, Masami Ouchi, Yoshiaki Ono, Takatoshi Shibuya, Ryohei Itoh, Ryota Kakuma, Akio K. Inoue, Haruka Kusakabe, Kazuhiro Shimasaku, Rieko Momose, Yuma Sugahara, Satoshi Kikuta, Shun Saito

Physics Faculty Research & Creative Works

We conduct intensity mapping to probe for extended diffuse Lyα emission around Lyα emitters (LAEs) at z ∼2-7, exploiting very deep (∼26 mag at 5σ) and large-area (∼4.5 deg2) Subaru/Hyper Suprime-Cam narrowband (NB) images and large LAE catalogs consisting of a total of 1540 LAEs at z = 2.2, 3.3, 5.7, and 6.6 obtained by the HSC-SSP and CHORUS projects. We calculate the spatial correlations of these LAEs with ∼1-2-billion-pixel flux values of the NB images, deriving the average Lyα surface brightness (SBLyα ) radial profiles around the LAEs. By carefully estimating systematics such as fluctuations of sky background and …

Using Differential Equations To Model A Cockatoo On A Spinning Wheel As Part Of The Scudem V Modeling Challenge, Miles Pophal, Chenming Zhen, Henry Bae

Rose-Hulman Undergraduate Mathematics Journal

For the SCUDEM V 2020 virtual challenge, we received an outstanding distinction for modeling a bird perched on a bicycle wheel utilizing the appropriate physical equations of rotational motion. Our model includes both theoretical calculations and numerical results from applying the Heaviside function for the swing motion of the bird. We provide a discussion on: our model and its numerical results, the overall limitations and future work of the model we constructed, and the experience we had participating in SCUDEM V 2020.

Waves And Oscillations In A Sunspot: Observations And Modeling Of Noaa Ar 12470, Yi Chai

Dissertations

Waves and oscillations are important solar phenomena not only because they can propagate and dissipate energy in the chromosphere, but also because they carry information about the structure of the atmosphere in which they propagate. Among these phenomena, the one of the most interesting ones occurs in the sunspot umbra. In this area, continuously propagating magnetohydrodynamic (MHD) waves generated from below the photosphere create the famous 3-minute sunspot umbral oscillations that affect the line profile of spectral lines due to temperature, density, and velocity changes of the plasma in the region. In the past decades, numerous observations and models have …

Nondestructive Evaluation Of 3d Printed, Extruded, And Natural Polymer Structures Using Terahertz Spectroscopy And Imaging, Alexander T. Clark

Dissertations

Terahertz (THz) spectroscopy and imaging are considered for the nondestructive evaluation (NDE) of various three-dimensional (3D) printed, extruded, and natural polymer structures. THz radiation is the prime candidate for many NDE challenges due to the added benefits of safety, increased contrast and depth resolution, and optical characteristic visualization when compared to other techniques. THz imaging, using a wide bandwidth pulse-based system, can evaluate the external and internal structure of most nonconductive and nonpolar materials without any permanent effects. NDE images can be created based on THz pulse attributes or a material’s spectroscopic characteristics such as refractive index, attenuation coefficient, or …

Numerical Methods For Optimal Transport And Optimal Information Transport On The Sphere, Axel G. R. Turnquist

Dissertations

The primary contribution of this dissertation is in developing and analyzing efficient, provably convergent numerical schemes for solving fully nonlinear elliptic partial differential equation arising from Optimal Transport on the sphere, and then applying and adapting the methods to two specific engineering applications: the reflector antenna problem and the moving mesh methods problem. For these types of nonlinear partial differential equations, many numerical studies have been done in recent years, the vast majority in subsets of Euclidean space. In this dissertation, the first major goal is to develop convergent schemes for the sphere. However, another goal of this dissertation is …

Periodic Fast Multipole Method, Ruqi Pei

Dissertations

Applications in electrostatics, magnetostatics, fluid mechanics, and elasticity often involve sources contained in a unit cell C, centered at the origin, on which periodic boundary condition are imposed. The free-space Green’s functions for many classical partial differential equations (PDE), such as the modified Helmholtz equation, are well-known. Among the existing schemes for imposing the periodicity, three common approaches are: direct discretization of the governing PDE including boundary conditions to yield a large sparse linear system of equations, spectral methods which solve the governing PDE using Fourier analysis, and the method of images based on tiling the plane with copies of …

Type I Error Rate Controlling Procedures For Multiple Hypotheses Testing, Beibei Li

Dissertations

This dissertation addresses several different but related topics arising in the field of multiple testing, including weighted procedures and graphical approaches for controlling the familywise error rate (FWER), and stepwise procedures with control of the false discovery rate (FDR) for discrete data. It consists of three major parts.

The first part investigates weighted procedures for controlling the FWER. In many statistical applications, hypotheses may be differentially weighted according to their different importance. Many weighted multiple testing procedures (wMTPs) have been developed for controlling the FWER. Among these procedures, two weighted Holm procedures are commonly used in practice: one is based …

Developing A Natural Language Processing Approach For Analyzing Student Ideas In Calculus-Based Introductory Physics, Jon M. Geiger, Lisa M. Goodhew, Tor Ole B. Odden

Honors Projects

Research characterizing common student ideas about particular physics topics has made a significant impact on university-level physics teaching by providing knowledge that supports instructors to target their instruction and by informing curriculum development. This work utilizes a Natural Language Processing algorithm (Latent Dirichlet Allocation, or LDA) to categorize student ideas, with the goal of significantly expediting the process of categorizing student ideas. We preliminarily test the LDA approach by applying the algorithm to a collection of introductory physics student responses to a conceptual question about circuits, specifically attending to whether it is useful for characterizing conceptual resources, or student ideas …

Dynamics Of Polymer Melts And Polymer Nanocomposites Studied By Broadband Dielectric Spectroscopy, Mengchun Wu

LSU Doctoral Dissertations

Materials based on polymers and polymeric nanocomposites have properties advantageous for many applications. In many cases, the physical behavior is connected to molecular motion. Polymers are macromolecules in which both fast local motions and slower chain relaxations may contribute to the material properties. Answering fundamental questions on the molecular dynamics is challenging, because of the existence of many different processes and the strong temperature dependence of the processes. An investigation covering a broad window over many orders of magnitude in the time scale is needed. Hence, dielectric spectroscopy is an appropriate tool to enhance fundamental understanding. This dissertation pays special …

Statistical Characteristics Of High-Frequency Gravity Waves Observed By An Airglow Imager At Andes Lidar Observatory, Alan Z. Liu, Bing Cao

Publications

The long-term statistical characteristics of high-frequency quasi-monochromatic gravity waves are presented using multi-year airglow images observed at Andes Lidar Observatory (ALO, 30.3° S, 70.7° W) in northern Chile. The distribution of primary gravity wave parameters including horizontal wavelength, vertical wavelength, intrinsic wave speed, and intrinsic wave period are obtained and are in the ranges of 20–30 km, 15–25 km, 50–100 m s−1, and 5–10 min, respectively. The duration of persistent gravity wave events captured by the imager approximately follows an exponential distribution with an average duration of 7–9 min. The waves tend to propagate against the local background winds and …

Tailored Resonant Waveguide Gratings For Augmented Reality, Matt Markowitz, Michele Cotrufo, You Zhou, Karl Stensvad, Craig Schard, Adam C. Overvig, Andrea Alù

Advanced Science Research Center

We explore the use of tailored resonant waveguide gratings (RWG) embedded in a glass-like matrix as angularly tolerant tri-band reflection filters under oblique excitation. Through inverse design we optimize 1D grating structures to support multi-frequency narrow- band resonances in an otherwise transparent background, ideally suited for augmented reality applications. In particular, we show theoretically and experimentally that a single RWG can be tailored to provide reflection levels larger than 50% under p-polarized excitation at three distinct wavelengths of choice, over a narrow bandwidth and within a substantial angular range around 58° incidence, while simultaneously eliminating ghost reflections from the glass/air …

In-Phantom Film Measurements Of Two Treatment Planning Systems For Single-Fraction Spine Sbrt, Michael J. Taylor

LSU Master's Theses

Purpose: Treatment planning accuracy for spine stereotactic body radiation therapy (SBRT) varies depending on the dose calculation algorithm utilized in the treatment planning system (TPS). This project compared the end-to-end accuracy between spine SBRT plans calculated in a convolution-superposition based TPS (TPS_CS) and Monte Carlo based TPS (TPS_MC) with radiochromic film measurements. The hypothesis was that TPS_MC would calculate the dose gradient in the critical region between the vertebral body and the spinal cord more accurately than TPS_CS.

Methods: Single-fraction spine SBRT treatments following RTOG 0631 and local institutional guidelines were planned in …

Event-Based Imaging Polarimeter, Michael R. Hawks, Michael L. Dexter

Faculty Publications

The design and initial experimental results from an event-based, rotating-polarizer, imaging polarimeter are presented. The speed of division-of-time imaging systems is traditionally constrained by the frame rate of the focal plane sensor and the need to sample several polarization angles during rotation. The asynchronous event reporting of event-based cameras (EBCs) frees these constraints but introduces challenges. The Stokes vectors used to describe polarization are based on irradiance, but EBCs are inherently change-detection systems that struggle to estimate irradiance. Two methods of estimating the polarization state without first recovering irradiance images are presented and compared. The DAVIS 346 sensor enables simultaneous …

Simulating Photo-Disintegration Of 137cs Radioactive Waste Using Various Energies Of Gamma Photons, Hassanain H. Alkazzaz, Asia H. Al-Mashhadani, Kamal H. Lateef

Karbala International Journal of Modern Science

In this study, the possibility of using gamma-ray in photo-disintegration method was examined so that it can be used in the remediation of 137Cs radionuclides waste materials by nuclear transmutation to convert long-lived nuclides to other isotopes nuclides, which are shorter half-life (or stable), by different photo-nuclear reaction channels (γ,n), (γ,2n), (γ,p), (γ, a), (γ,d). A simulation code has been written using MATLAB for conducting calculations of reduction and residual. The results showed that gamma-ray fluxes below 1017 [cm-2 s-1] are not adequate to perform effective incinera-tion of 137Cs, and as for gamma flux of 1018 [cm-2 s-1] it showed …

Distributed X-Ray Sources For X-Ray Imaging And Small Animal Flash Irradiator, Yuewen Tan

Arts & Sciences Graduate Student Theses and Dissertations

Emerging distributed x-ray source technology enables new designs for x-ray imaging systems. The multi-pixel thermionic emission X-ray (MPTEX) source, a distributed x-ray source developed in our lab, was assembled and tested. With a multi-row CdTe photon-counting detector, forty-eight x-ray fan beams of MPTEX source were able to cover a 25-cm cross-sectional and 8-cm axial field of view. Tetrahedron-beam x-ray imaging techniques using MPTEX source were demonstrated.Ultra-high dose rate radiotherapy or FLASH radiotherapy (RT) potentially can reduce normal tissue toxicity in radiation treatments. A compact irradiator that can deliver FLASH-RT treatments similar to conventional RT treatments is needed for preclinical studies. …

Artificial Intelligence, Controls, And Sensor Fusion For Optimization And Modeling Of Space Missions And Particle Accelerators, Reza Pirayeshshirazinezhad

Mechanical Engineering ETDs

This PhD dissertation is devoted to developing artificial intelligence (AI) applications for space missions and particle accelerators considering constraints on the computational resources. The space mission studied in this research, the Virtual Telescope for X-ray Observations (VTXO), is the mission exploiting 2 6U-CubeSats operating in a precision formation. The goal of the VTXO project is to develop a space-based, X-ray imaging telescope with high angular resolution precision. VTXO space mission is designed and the mission is optimized to increase the performance of the mission. Trajectory optimization with AI, hybrid control, control algorithms, and high performance computing are all used to …

Monitoring Bacteria Cultures Using Near Infrared (Nir) Binary Spectronephelometry (Bsn), Raman Spectra And Principal Component Analysis (Pca), Steven Ortiz

Dissertations - ALL

Current noninvasive methods cannot continuously and simultaneously monitor the concentrations of cells and media components that define the state of native bacterial cultures, because of changing turbidity. A new technique, binary spectronephelometry (BSN) has the same or better sensitivity and precision for population monitoring as optical density at 600nm (OD600), while simultaneously measuring metabolic processes. The BSN algorithm uses laser induced emission to probe mildly turbid media i.e., propagation of light occurs in the single scattering regime. A BSN "training set" associates a grid of elastic emission measurements, comprising Rayleigh and Mie scattering, and inelastic emission measurements, comprising fluorescence and …

Probing Lepton Flavour Universality With $\Bz \To \Kstarz \Taup \Taum$, Aravindhan Venkateswaran

Dissertations - ALL

Neutral current $\bquark \to \squark ll$ processes have long been known to be precise probes of physics beyond the Standard Model. A pattern of anomalies seen in $\bquark \to \squark \mup \mun$ and in $\bquark \to \cquark \tau \nu$ data has hinted at the violation of lepton flavour universality. Effective field theories which attempt to find an explanation for these anomalies predict sizeable enhancements to the rate of $\bquark \to \squark \taup \taum$ currents. We use $pp$ collision data collected by the LHCb detector to estimate a sensitivity of $\BF(\Bz \to \Kstarz \taup \taum) < 1.5 \times 10^{-3}$ at 95\% C.L.

Exploring The Solar System Through Space And Time Via Laboratory Investigations Of Extraterrestrial Material, Kainen Lee Utt

Arts & Sciences Graduate Student Theses and Dissertations

This dissertation reports the results of laboratory studies of lunar soil samples, gas-to-solid filamentary enstatite grains from a likely-cometary interplanetary dust particle (IDP), and exogenous clasts in the CH3 chondrite Acfer 182 that likely originated from a differentiated basaltic planetesimal. These studies were performed using multi-instrument analyses involving high-resolution scanning and transmission electron microscopy (SEM/TEM) techniques, nanoscale secondary ion mass spectrometry (NanoSIMS), synchrotron infrared nanospectroscopy (SINS), electron probe microanalysis (EPMA), and Raman spectroscopy. The results of these analyses are used to examine space weathering phenomena, energetic processing and radial transport in the protoplanetary disk, and the origins of igneous inclusions …

Correlation Functions Of The Anharmonic Oscillator: Numerical Verification Of Two-Loop Corrections To The Large-Order Behavior, Ludovico T. Giorgini, Ulrich D. Jentschura, Enrico M. Malatesta, Giorgio Parisi, Tommaso Rizzo, Jean Zinn-Justin

Physics Faculty Research & Creative Works

Recently, the large-order behavior of correlation functions of the O(N)-anharmonic oscillator has been analyzed by us [L. T. Giorgini et al., Phys. Rev. D 101, 125001 (2020)PRVDAQ2470-001010.1103/PhysRevD.101.125001]. Two-loop corrections about the instanton configurations were obtained for the partition function, the two-point and four-point functions, and the derivative of the two-point function at zero momentum transfer. Here, we attempt to verify the obtained analytic results against numerical calculations of higher-order coefficients for the O(1), O(2), and O(3) oscillators, and we demonstrate the drastic improvement of the agreement of the large-order asymptotic estimates and perturbation theory upon the inclusion of the two-loop …

An Interdisciplinary Approach To Understanding Volcanoes And Their Processes, Katherine Cosburn

Physics & Astronomy ETDs

To better understand volcanoes and their processes is important from both a fundamental science perspective and for hazard monitoring purposes. The complexity and limitations we face in pursuing such a science are numerous and this dissertation explores how an interdisciplinary approach combining physics, computer science, and volcanology can address this complexity in a straightforward and meaningful way. This is achieved through various modelling techniques across three studies: (1) a first-order analytic modelling of stratovolcano topographic shape, (2) the use of a Bayesian joint inversion on gravity and novel cosmic-ray muon measurements for imaging flat-lying subsurface density anomalies, and (3) the …

Bio-Based Antibacterial Packaging From Decorated Bagasse Papers With Natural Rosin And Synthesised Go-Ag Nanoparticles, Mohamed Morsy

Nanotechnology Research Centre

No abstract provided.

Direct Simulation And Reduced-Order Modeling Of Premixed Flame Response To Acoustic Modulation, Zheng Qiao

Theses and Dissertations

This dissertation introduces a general, predictive and cost-efficient reduced-order modeling (ROM) technique for characterization of flame response under acoustic modulation. The model is built upon the kinematic flame model–G-equation to describe the flame topology and dynamics, and the novelties of the ROM lie in i) a procedure to create the compatible base flow that can reproduce the correct flame geometry and ii) the use of a physically-consistent acoustic modulation field for the characterization of flame response. This ROM addresses the significant limitations of the classical kinematic model, which is only applicable to simple flame configurations and relies on ad-hoc models …

Insights Into Molecular Recognition And Reactivity From Molecular Simulations Of Protein-Ligand Interactions Using Md And Qm/Mm, Jerrano L. Bowleg

Theses and Dissertations

In this thesis, we have employed two computational methods, molecular dynamics (MD) and hybrid quantum mechanics/molecular mechanics (QM/MM) MD simulations with umbrella sampling (US), to gain insights into the molecular mechanism governing the molecular recognition and reactivity in several protein-ligand complexes. Three systems involving protein-ligand interactions are examined in this dissertation utilizing well-established computational methodologies and mathematical modeling. The three proteins studied here are acetylcholinesterase (AChE), butyrylcholinesterase (BChE), and peptidyl-prolyl cis-trans isomerase NIMA-interacting 1 (PIN1). These enzymes are known to interact with a variety of ligands. AChE dysfunction caused by organophosphorus (OP) chemicals is a severe hazard since AChE is …

The Interaction Of Topological Defects In Anisotropically-Elastic Nematic Liquid Crystals, Carter J. Swift

Macalester Journal of Physics and Astronomy

Topological defects are very well understood so long as the medium in which they exist is isotropically-elastic. They lead to director fields which are easy to calculate and superpose linearly so that a system with any number of defects is analytically treatable. They also have an interaction which is simple in form and can be accurately described by the Peach-Koehler force. In an anisotropically-elastic medium, however, such defects are very poorly understood outside of the single-defect case which was solved by Dzyaloshinskii. In this project, numerical and approximate analytical techniques are applied in order to better understand the interaction between …