Other Physics Commons^™

Horizon Content Knowledge And Its Integration Into Physics Education Research: Case Study Analysis On Physical Science And Physics Teachers, Trevor A. Robertson

Electronic Theses and Dissertations

Teachers focused on just one year of instruction may neglect what students need most– a coherent structure of learning across disciplines that advances students’ understanding. The topic of coherence has been a major motivator for education research, including investigations in student- teacher interactions, epistemological beliefs, and large-scale curricular reform. One framework of knowledge, horizon content knowledge (HCK), can aid in describing the knowledge a teacher needs to see beyond their own instruction and provide a coherent structure for students.

While horizon content knowledge exists in one of the most widely adopted teacher frameworks of knowledge in mathematics, mathematical knowledge for …

Domain Wall Saddle Point Morphology In Ferroelectric Triglycine Sulfate, C. J. Mccluskey, A. Kumar, Alexei Gruverman, I. Luk’Yanchuk, J. M. Gregg

Alexei Gruverman Publications

Ferroelectric domain walls, across which there is a divergence in polarization, usually have enhanced electrical conductivity relative to bulk. However, in lead germanate, head-to-head and tail-to-tail walls are electrically insulating. Recent studies have shown that this is because, when oppositely oriented domains meet, polar divergence is obviated by a combination of domain bifurcation and suspected local dipolar rotation. To explore the uniqueness, or otherwise, of this microstructure, we have used tomographic piezoresponse force microscopy to map three-dimensional domain morphologies in another uniaxial ferroelectric system: triglycine sulfate. This mapping reveals an abundance of domain wall saddle points, which are characteristic of …

Extending The Lifetime Of Optically Stimulated Dosimeters For Use In Output Checks At Iroc- Houston, Hayden Scott

Dissertations & Theses (Open Access)

Purpose: Optically Stimulated Luminescent Dosimeters (OSLDs) are a prominent form of in-vivo dosimeter used both in clinics as well as for the audits of radiological
equipment at the Imaging and Radiation Oncology Core (IROC)-Houston. These
dosimeters have a recommended dose limit of 10 Gy due to a change in signal response with dose. To assist with the OSLD operation at IROC-Houston, evaluating the signal response of these dosimeters with IROC’s methodologies offers the potential to extend the dose limit past 10 Gy, improve the efficiency of handling OSLDs, and reduce the cost and time spent on commissioning OSLDs.
Methods: The …

Fabrication, Measurements, And Modeling Of Semiconductor Radiation Detectors For Imaging And Detector Response Functions, Corey David Ahl

Doctoral Dissertations

In the first part of this dissertation, we cover the development of a diamond semiconductor alpha-tagging sensor for associated particle imaging to solve challenges with currently employed scintillators. The alpha-tagging sensor is a double-sided strip detector made from polycrystalline CVD diamond. The performance goals of the alpha-tagging sensor are 700-picosecond timing resolution and 0.5 mm spatial resolution. A literature review summarizes the methodology, goals, and challenges in associated particle imaging. The history and current state of alpha-tagging sensors, followed by the properties of diamond semiconductors are discussed to close the literature review. The materials and methods used to calibrate the …

Computational Modeling Of Superconductivity From The Set Of Time-Dependent Ginzburg-Landau Equations For Advancements In Theory And Applications, Iris Mowgood

Computational and Data Sciences (PhD) Dissertations

A full review of the research conducted and published during my PhD studies in Computational and Data Sciences at Chapman University, under the advisement of Dr. Armen Gulian, are presented. Using the set of time-dependent Ginzburg-Landau (TDGL) equations with inclusion of the interference current and the non-equilibrium phonon term, we modeled the dynamics of superconductors in various theory revealing states and practical purposes. A review of the history and phenomenon of superconductivity, including modern applications, is introduced. The Josephson effect and associated Josephson junction are discussed for comparison to our analogous results with the 1-D superconducting wire. The mathematics of …

Response Of The Isothermal Mode Grüneisen Tensor Across Phase Boundaries, Jasmine K. Hinton

UNLV Theses, Dissertations, Professional Papers, and Capstones

The assumptions for the 1912 Grüneisen parameter are reviewed, particularly in the cases of anisotropy, high temperatures, and across phase boundaries. Two main case studies are shown: β-Sn, and Cd. The main techniques of this work involve resistively heated diamond anvil cells with both optical Raman spectroscopy and x-ray diffraction. It is found in Sn that the isothermal mode Grüneisen tensor along increasing isotherms diverges from the single-valued temperature aggregate at the onset of melt, and this is proposed to use as a method of exploring melt phase boundaries in other systems. This method is examined once again on another …

Simulating Radial Ring Structure With An Ambipolar Elsasser (Am) Bump In Non-Ideal Magnetohydrodynamics Of Protoplanetary Disks, Aleksey S. Mohov

UNLV Theses, Dissertations, Professional Papers, and Capstones

Rings are one of the most ubiquitous substructures observed in protoplanetary disks. They are known to be a robust site for planetesimal formation; thus we look for mechanisms that can originate stable rings. From chemical modelling of snow lines, we expect a bump in the Ambipolar Diffusion (AD) Elssaser number (Am) in the radial direction. We use the Athena++ code to model the non-ideal Magentohydrodynamics (MHD) behavior of an Am bump. We explore a parameter space of Gaussian bumps with Am = 5, 1, 0.5 peak strength and σ = 0.25, 1, 5. The Gaussian profile is inserted into the …

Stoichiometric Determination Of Hydride Materials At Extreme Conditions, Gregory Alexander Smith

UNLV Theses, Dissertations, Professional Papers, and Capstones

Hydrogen was predicted to be a high-temperature superconductor at near-megabar conditions in 1968,[1] but only recently was been experimentally observed.[2] This is due to the extraneous metrological constraint of requiring 5 megabars of pressure to stabilize. A more practical approach for synthesis of high-temperature superconductors has been pro-posed through the use of hydride compounds. Recently, a surge of rare earth hydrides have achieved critical superconducting transition temperatures (T_C ) close to room temperature.[3, 4, 5, 6] However, due to limitations of the necessary instrumentation to achieve megabar pressures, many techniques traditionally used to measure stoichiometry are unavailable.Three works presented in …

Characterization Of 2d Quantum Materials Using Ai And Large-Scale Quantum Data Collection, Apoorva Bisht

Computer Science and Computer Engineering Undergraduate Honors Theses

2D materials like hexagonal boron nitride, graphene, and tungsten diselenide are widely utilized for studying their unique mechanical and opto-electronic properties to exploit them to make transistors and fabricating a variety of other devices. All these applications require that the 2D materials used be of specific uniform thickness. Until very recently, this process has been largely manual and tedious. However, few applications exploit the characteristic color-to-thickness correspondence of these near-transparent materials. To continue this effort, in this work we create a large-scale dataset for three different materials (hBN, graphene, and WSe$_2$) to train and test an image segmentation model along …

The Safe And Effective Clinical Deployment Of Artificial Intelligence Tools, Kelly Nealon

Dissertations & Theses (Open Access)

18 million new cancer cases are diagnosed each year. Roughly half of these patients will be treated with radiation therapy, a complex technique that requires an interdisciplinary team of clinical staff and expensive equipment to be delivered safely. Cancer centers in Low- and Middle-Income Countries (LMIC) have an especially difficult time meeting the demands of radiation therapy as the complexity of treatment techniques increase, with only 37% of patients in these regions having access to the care they need. Artificial Intelligence (AI) based tools are being developed to simplify the treatment planning and quality assurance processes to increase the number …

Joint Constraints On Kepler-36 From Kepler And New Keck-Hires Data, Nicholas Juliano

UNLV Theses, Dissertations, Professional Papers, and Capstones

I analyze new HIRES Radial Velocity (RV) data in conjunction with transit mid-times and uncertainties from the full 17 quarters of Kepler data to reassess the orbital parameters of the Kepler-36 system. Six additional RV measurements were taken by the Keck-HIRES spectrograph from September 21, 2021 to October 11, 2021. I carry out a differential evolution Markov Chain Monte Carlo-based (DEMCMC) analysis to infer improved orbital elements for the two known planets in the system. Leveraging additional information provided by the new RV measurements, I extend this DEMCMC analysis to a possible three-planet configuration. I explore the likelihood of a …

Treatment Planning Automation For Rectal Cancer Radiotherapy, Kai Huang

Dissertations & Theses (Open Access)

Background

Rectal cancer is a common type of cancer. There is an acute health disparity across the globe where a significant population of the world lack adequate access to radiotherapy treatments which is a part of the standard of care for rectal cancers. Safe radiotherapy treatments require specialized planning expertise and are time-consuming and labor-intensive to produce.

Purpose:

To alleviate the health disparity and promote the safe and quality use of radiotherapy in treating rectal cancers, the entire treatment planning process needs to be automated. The purpose of this project is to develop automated solutions for the treatment planning process …

Monoenergetic Neutrinos From Wimp Annihilations In Jupiter, George French

Undergraduate Honors Theses

Several important lines of evidence point to the existence of dark matter, but it has not yet been experimentally detected. There are several proposed candidates for what dark matter is like, the most popular being weakly interacting massive particles (WIMPs). It has been well-established in the literature that WIMPs would be captured by the Sun after scattering off of atomic nuclei to a velocity lower than the escape velocity. Over time, many WIMPs would be captured and begin to annihilate in the solar core; this would result in the production of kaons that decay at rest into monoenergetic 236 MeV …

Pion Detection For The Moller Parity-Violating Electron Scattering Experiment, Michael Tristan Hurst

Undergraduate Honors Theses

The MOLLER Experiment at Jefferson Lab intends to make a precise measurement of the weak charge of the electron through parity-violating electron scattering. To achieve the level of precision required for the experiment, background rates of events other than electron-electron scattering must be known. Working with data from Monte-Carlo simulations created using a GEANT4 simulation package, I show that the combined signal from two existing detector subsystems of the MOLLER experiment allow for particle identification between electron and pion events. I worked to optimize an additional ‘Pion Exit Scintillator’ which improves the ability to distinguish particle identity at the cost …

Studies Of The Ionosphere-Thermosphere Responses To Multi-Scale Energy Deposition Processes, Haonan Wu

All Dissertations

The Ionosphere-Thermosphere (I-T) system is greatly affected by the magnetospheric energy deposition from above and subjected to forcing from the lower atmosphere simultaneously. A central problem in studying the coupled I-T system is to analyze the multi-scale processes naturally embedded in both ways. Magnetospheric energy input such as auroral precipitation and electric field demonstrates multi-scale structures during magnetic storms, resulting in multi-scale I-T responses when deposited into the I-T system. To better quantify the multi-scale aurora and electric field, we developed a new data assimilation model based on a multi-resolution Gaussian process model to synthesize empirical models and observational data …

An Investigation Into The Physical Properties Governing The​ Coupled Harmonic Oscillator​, Ethan Taylor, Jj Rivera

ATU Research Symposium

The coupled harmonic oscillator is an extremely important model in physics - especially in the field of solid state physics where the forces that tie atoms to their equilibrium positions are much stronger than their inter-atomic coupling forces. Given a coupled spring-mass system, we want to theoretically determine and then experimentally verify the normal frequencies involved in coupled harmonic oscillation. To do so, a coupled spring-mass system was built using an air track, carts, and PASCO motion detectors, the normal frequencies were theoretically calculated, and then we experimentally verified these normal frequencies with 4 trials: Symmetric, Antisymmetric, and two Mixed …

One-Dimensional And Two-Dimensional Simulations Of Helical Homopolymers: A Comparative Analysis Of Energy Stabilization And Efficiency​, Nathan Roberts, Matthew Hooks

Scholars Week

The purpose of our work is to analyze the results of a two-dimensional parallel tempering Monte Carlo simulation of a coarse-grained helical homopolymer. The two-dimensional simulation allows Hamiltonian exchanges across both temperature and torsion values, while the one-dimensional simulation exclusively exchanges across temperature values. The genesis of each simulation is defined by a randomly configured polymer; as time progresses, randomly generated movements of monomers decrease the structure’s energy until equilibrium is reached. Equilibrium is determined by finding the absolute minimum of the data series, computing the mean of all remaining data, and finding the intersection between the rolling average and …

An Analysis Of Energy Production And Efficiency In Various Longbow Archery Models, Hannah Mcpherson

Honors Projects

An analysis of the energy production and efficiency of three lab-tested longbow models is undertaken. The first model, which is constructed to not allow flexing of limbs and which uses a frictionless cart and track in place of an arrow, demonstrated an efficiency of 50% +/- 40%. The second model, which is constructed similarly to the first with the exception of a wooden dowel now being used as an arrow-like object, demonstrated an efficiency of 13% +/- 3%. The last model, a 3D printed longbow with flexible limbs using the wooden dowel as an arrow-like object, demonstrated an efficiency of …

Carbon Dioxide-Induced Corrosion Of Aisi 4140 Steel In Acidified Artificial Geothermal Brine, Anawati Anawati, Rayhan Izzat, Riene Kaelamanda Pragitta, Rafli Ihsan Hernandi

Makara Journal of Science

Carbon dioxide (CO₂)-induced corrosion often occurs in the structural materials of geothermal industry. The presence of CO₂ influences the formation of various corrosion products. This research investigates the effect of dissolved CO₂ in acidic brines on the corrosion behavior of AISI 4140 steel at atmospheric pressure. The brines were the standard brine, Ca-free brine, and high-salinity brine. The corrosion behavior was studied using electrochemical and immersion tests. A cyclic polarization test showed that the corrosion rate was higher in dissolved CO₂ brine than in non-CO₂ brine, and an immersion test demonstrated a similar result. …

High-Frequency Diode Effect In Superconducting Nb3Sn Microbridges, Sara Chahid, Serafim Teknowijoyo, Iris Mowgood, Armen Gulian

Mathematics, Physics, and Computer Science Faculty Articles and Research

The superconducting diode effect has recently been reported in a variety of systems and different symmetry-breaking mechanisms have been examined. However, the frequency range of these potentially important devices still remains obscure. We investigated superconducting microbridges of Nb3Sn in out-of-plane magnetic fields; optimum magnetic fields of ∼10 mT generate ∼10% diode efficiency, while higher fields of ∼15–20 mT quench the effect. The diode changes its polarity with magnetic field reversal. We documented superconductive diode rectification at frequencies up to 100 kHz, the highest reported as of today. Interestingly, the bridge resistance during diode operation reaches a value that is a …