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Full-Text Articles in Physical Sciences and Mathematics

Understanding Students’ Global Interdependence In Science Instruction, Walter S. Smith Dec 2021

Understanding Students’ Global Interdependence In Science Instruction, Walter S. Smith

Journal of Global Education and Research

Multiple American educational organizations such as the National Education Association, Association for Supervision and Curriculum Development, and the Council of Chief State School Officers have advocated for globalizing the K-12 curriculum. The National Science Teaching Association (NSTA) in a position statement on international education and the Next Generation Science Standards have produced goals and standards for internationalizing the science curriculum by addressing topics such as climate change, environment, and disease that cross borders. In contrast to those pronouncements on the curriculum, this article views global science education through an instructional lens that focuses on a students’ global interdependence in science ...


Stay Calm And Focus On The Learning Outcomes: Tools For Taking Biophysical Chemistry Online, Maria Ballester, Brian L. Van Hoozen Jr., Arthur Sikora Aug 2021

Stay Calm And Focus On The Learning Outcomes: Tools For Taking Biophysical Chemistry Online, Maria Ballester, Brian L. Van Hoozen Jr., Arthur Sikora

Chemistry and Physics Faculty Articles

Course specific learning outcomes are an important tool to define the scope of a course and can be very helpful when designing experiments and assessments. With slight modification, these learning outcomes can serve as a guide when transitioning to the distance learning format especially in courses with a traditional lab. Here we present such an example for the biophysical chemistry course.


On-Chip Nanoscale Plasmonic Optical Modulators, Abdalrahman Mohamed Nader Abdelhamid Jun 2021

On-Chip Nanoscale Plasmonic Optical Modulators, Abdalrahman Mohamed Nader Abdelhamid

Theses and Dissertations

In this thesis work, techniques for downsizing Optical modulators to nanoscale for the purpose of utilization in on chip communication and sensing applications are explored. Nanoscale optical interconnects can solve the electronics speed limiting transmission lines, in addition to decrease the electronic chips heat dissipation. A major obstacle in the path of achieving this goal is to build optical modulators, which transforms data from the electrical form to the optical form, in a size comparable to the size of the electronics components, while also having low insertion loss, high extinction ratio and bandwidth. Also, lap-on-chip applications used for fast diagnostics ...


Clustering And Halo Abundances In Early Dark Energy Cosmological Models, A. Klypin, V. Poulin, F. Prada, J. Primack, M. Kamionkowski, V. Avila-Reese, A. Rodriguez-Puebla, P. Behroozi, D. Hellinger, Tristan L. Smith Jun 2021

Clustering And Halo Abundances In Early Dark Energy Cosmological Models, A. Klypin, V. Poulin, F. Prada, J. Primack, M. Kamionkowski, V. Avila-Reese, A. Rodriguez-Puebla, P. Behroozi, D. Hellinger, Tristan L. Smith

Physics & Astronomy Faculty Works

Cold Dark Matter with cosmological constant (ΛCDM) cosmological models with early dark energy (EDE) have been proposed to resolve tensions between the Hubble constant H0=100h km ṡ−1Ṁpc−1 measured locally, giving h ≈ 0.73, and H0 deduced from Planck cosmic microwave background (CMB) and other early-Universe measurements plus ΛCDM, giving h ≈ 0.67. EDE models do this by adding a scalar field that temporarily adds dark energy equal to about 10 per cent of the cosmological energy density at the end of the radiation-dominated era at redshift z ∼ 3500. Here, we compare linear and non-linear predictions of a ...


Skyrmions And Biskyrmions In Magnetic Films, Daniel Capic Jun 2021

Skyrmions And Biskyrmions In Magnetic Films, Daniel Capic

Dissertations, Theses, and Capstone Projects

Skyrmions have garnered significant attention in condensed matter systems in recent years. In principle, they are topologically protected, so there is a large energy barrier preventing their annihilation. Furthermore, they can exist at the nanoscale, be manipulated with very small currents, and be created by a number of different methods. This makes them attractive for use in potential computing applications. This work studies ferromagnetic skyrmions. In particular, it highlights our small contributions to the field of skyrmions in condensed matter systems, specifically in thin-film ferromagnets.


Development Of A Diamond Defect Quantum Sensing Platform For Probing Novel Quantum Magnetic Phases, Jeffrey Ahlers May 2021

Development Of A Diamond Defect Quantum Sensing Platform For Probing Novel Quantum Magnetic Phases, Jeffrey Ahlers

Senior Honors Papers / Undergraduate Theses

Nitrogen vacancy centers in diamond are highly effective quantum sensors due to their high spatial resolution and high magnetic field sensitivity. We present the construction of an optically detected magnetic resonance platform in order to facilitate the probing of magnetic phases in two-dimensional heterostructures. This includes the characterization of the required microwave voltage controlled oscillator and amplifier. In the presence of crystal strain, we measure ensemble nitrogen vacancy spin transitions with and without an applied magnetic field, and observe frequency shifts consistent with sample heating.


Characterization Of Landslide Processes From Radar Remote Sensing And Hydromechanical Modeling, Yuankun Xu May 2021

Characterization Of Landslide Processes From Radar Remote Sensing And Hydromechanical Modeling, Yuankun Xu

Earth Sciences Theses and Dissertations

Landsides are a natural geomorphic process yet a dangerous hazard which annually causes thousands of casualties and billions of property loss in a global scale. Understanding landslide motion kinematics from early initiation to final deposition is critical for monitoring, assessing, and forecasting landslide movement in order to mitigate their hazards. Landslides occur under diverse environmental settings and appear in variable types; however, all types of landslides can be mechanically attributed to shearing failure at the basal surface due to stress regime shift contributed by internal and/or external forcing. Typical internal factors include soil/rock weathering, whereas typical external triggering ...


Sampling Candidate Reionization Galaxies Using Spectral Energy Distribution Fitting, Nicholas J. Velikonja, Michael Rutkowski May 2021

Sampling Candidate Reionization Galaxies Using Spectral Energy Distribution Fitting, Nicholas J. Velikonja, Michael Rutkowski

Macalester Journal of Physics and Astronomy

The process of reionization is one of the major pieces of galaxy evolution which remain to be un- derstood. With new observational tools like JWST on the horizon, imaging reionization-era galaxies will soon be possible. However, because the ionizing radiation is absorbed by the neutral hydrogen it ionizes, observers need some other parameter by which to identify those galaxies capable of reionizing. The search for ionizing emission via related parameters is well underway, and has come up with some tentative correlations, yet a consistent indicator or set of indicators remains to be discovered. New data in the Low-Redshift Lyman Continuum ...


Laser-Excitation Spectroscopy Of Niobium Hydride And Tantalum Hydride, Siddhant Singh May 2021

Laser-Excitation Spectroscopy Of Niobium Hydride And Tantalum Hydride, Siddhant Singh

Macalester Journal of Physics and Astronomy

The experimental results presented in this paper shed light on some of the fundamental bonding characteristics of NbH and TaH. Six bands of niobium hydride and five weak bands of tantalum hydride were observed for the first time using laser excitation spectroscopy. The rotational assignments of observed bands were confirmed using dispersed fluorescence experiments for NbH and by checking the internal consistency of a global least squares fit for the weaker bands of TaH. For TaH, we were able to determine the term energies and molecular constants of each of its observed states to a high degree of accuracy by ...


Carrier Lifetime And Carrier Mobility Of Gaasn With Changing Nitrogen Concentration, Sun Gyu Park May 2021

Carrier Lifetime And Carrier Mobility Of Gaasn With Changing Nitrogen Concentration, Sun Gyu Park

Macalester Journal of Physics and Astronomy

In this work, we conducted Ultrafast Conductivity Measurements, using THz Spectroscopy to characterize the carrier mobility and the carrier lifetime of gallium arsenide nitride (GaAsN) thin films with a range of Nitrogen concentrations. The photoexcitation of semiconductor samples excites free charges by promoting electrons from the valence band to the conduction band. We then measure the change in conductivity by measuring the transmission of a THz electromagnetic pulse after photoexcitation and comparing with the signal that was measured without photoexcitation. The values of transmission are then converted into conductivity, from which we derive the carrier concentration and scattering time of ...


Automatic Leptonic Tensor Generation For Beyond The Standard Model (Bsm) Theories, Diego F. Lopez Gutierrez May 2021

Automatic Leptonic Tensor Generation For Beyond The Standard Model (Bsm) Theories, Diego F. Lopez Gutierrez

Macalester Journal of Physics and Astronomy

With the development of the Deep Underground Neutrino Experiment (DUNE) and Tokai-to-Hyper-Kamiokande (T2HK), we are entering the era of high-precision neutrino measurements. The colossal output of data from DUNE, plus the current data from several other neutrino experiments, will require a fast and efficient method of testing our BSM models in event generators. However, current methods for implementing a BSM theory in the event generators are prone to errors and time-consuming. We propose a novel program capable of automatically calculating the leptonic tensor for a given quantum field theory Lagrangian. This program is written in Python and utilizes the Universal ...


Model Of Electromagnetic Waves In An Axion-Induced Parity Symmetry Violation, Sarah Lipstone May 2021

Model Of Electromagnetic Waves In An Axion-Induced Parity Symmetry Violation, Sarah Lipstone

Macalester Journal of Physics and Astronomy

Axion particles have been postulated to resolve the strong CP problem in Quantum chromodynamics. The axion field may double as the inflaton field that produces cosmic inflation. In this project, we use a combination of analytical and numerical analysis to study how axion-induced parity symmetry violation affects the dynamics of electromagnetic waves.


Renewing The Paradigm: Simulating The Miso Region Electrical Grid Using Renewable Energy Generation With Implementation Of Long-Term Hydrogen Storage, Jackson C. Henningfield May 2021

Renewing The Paradigm: Simulating The Miso Region Electrical Grid Using Renewable Energy Generation With Implementation Of Long-Term Hydrogen Storage, Jackson C. Henningfield

Macalester Journal of Physics and Astronomy

The current electrical grid regime is not optimized to include renewable sources of power generation such as wind and solar. Electrical storage, as of now, is primarily established through the short-term generation and demand-meeting consumption leaving much of the grid susceptible to inefficiencies and power loss during natural events that leave grids out of commission. Delineating a new type of long-term storage, a hydrogen fuel cell, would ensure a reliable source of power to the masses regardless of the physical and climatic geography. The MISO region provides a perfect case study to introduce the ideas of diverse energy generation and ...


Electrical Grid Energy Storage Using Hydrogen: A Feasibility Study, Elizabeth M. Curtiss May 2021

Electrical Grid Energy Storage Using Hydrogen: A Feasibility Study, Elizabeth M. Curtiss

Macalester Journal of Physics and Astronomy

In this project, we studied the possibility of implementing hydrogen as energy storage. With the focus being on decarbonizing the grid, we looked at studies that were powered by renewable sources. In addition to utilizing renewable sources, we decided to study electrolysis as a way to produce hydrogen. Electrolysis is the splitting of water to obtain hydrogen and oxygen, which is a carbon free technique. Pulling from two different papers, we were able to construct an equation that modeled the levelized cost of producing hydrogen. We also calculated the levelized cost of a fuel cell too, with hydrogen as fuel ...


Particle Dynamics From The Method Of Nonlinear Realizations And Maxwell Group, Daniel S. Clark May 2021

Particle Dynamics From The Method Of Nonlinear Realizations And Maxwell Group, Daniel S. Clark

Macalester Journal of Physics and Astronomy

Professor Tonnis ter Veldhuis provides Macalester students with research opportunities in theoretical physics. In the Summer of 2020, a team of three students were introduced to the method of nonlinear realization of symmetries by studying Prof. Veldhuis’s prior research regarding an application of the method to membrane dynamics (1). Subsequent developments of this prior work involved research into torsion and riemann curvature tensors, as well as metric compatibility, highlighting the connection between symmetry and space-time structure. The foundation of this work was the D=4 Poincare algebra in the D=3 Lorentz group covariant form. After this introduction, each ...


Virtual Prototyping Of Liquid Lithium Divertor Concepts, Brennan Arnold May 2021

Virtual Prototyping Of Liquid Lithium Divertor Concepts, Brennan Arnold

Macalester Journal of Physics and Astronomy

A tokamak divertor must withstand power deposition in excess of 10 MW/m^2 in steady state and much higher in disruptions, enough to destroy nearly any material. In order to handle this extreme heat, there is some interest in using liquid metal flows to continually renew the divertor surface. In this paper, we examine an idea for a divertor with a porous surface that allows liquid lithium flowing through the divertor to percolate to the plasma facing surface. This idea is complicated by magnetohydrodynamic drag, where the stong magnetic fields in the tokamak cause the lithium to flow too ...


Modeling Gyrating Motion Using Mathematica, Jonathan Alvarado-Gomez May 2021

Modeling Gyrating Motion Using Mathematica, Jonathan Alvarado-Gomez

Macalester Journal of Physics and Astronomy

In this report I will describe a method of creating animations of gyrating objects in Mathematica [4]. There are 4 inputs to a function called trajectory, which are a time step, maximum time duration, initial force vector, and a 3x3 matrix that represents a tensor for the gyration of the object. I utilized the computer program Mathematica [4] to create 3D images of a gyrating object in the object frame of view. A collection of these images were put together in order to make an animation, which can be used as a tool for future researchers to investigate interesting paths ...


Spirals And Skyrmions In Antiferromagnetic Triangular Lattices, Wuzhang Fang, Aldo Raeliarijaona, Po-Hao Chang, Alexey Kovalev, Kirill Belashchenko May 2021

Spirals And Skyrmions In Antiferromagnetic Triangular Lattices, Wuzhang Fang, Aldo Raeliarijaona, Po-Hao Chang, Alexey Kovalev, Kirill Belashchenko

Faculty Publications, Department of Physics and Astronomy

We study realizations of spirals and skyrmions in two-dimensional antiferromagnets with a triangular lattice on an inversion-symmetry-breaking substrate. As a possible material realization, we investigate the adsorption of transition-metal atoms (Cr, Mn, Fe, or Co) on a monolayer of MoS2, WS2, or WSe2 and obtain the exchange, anisotropy, and Dzyaloshinskii-Moriya interaction parameters using first-principles calculations. Using energy minimization and parallel-tempering Monte Carlo simulations, we determine the magnetic phase diagrams for a wide range of interaction parameters. We find that skyrmion lattices can appear even with weak Dzyaloshinskii-Moriya interactions, but their stability is hindered by magnetic anisotropy. However, a weak easy ...


Inspection Of Electronics Components For Cryogenic Temperature Operation, Navaneeth Poonthottathil, Frank Krennrich, Amanda Weinstein, Jonathan Eisch, Leonard J. Bond, Dan Barnard, Zhan Zhang, Lucas Koester May 2021

Inspection Of Electronics Components For Cryogenic Temperature Operation, Navaneeth Poonthottathil, Frank Krennrich, Amanda Weinstein, Jonathan Eisch, Leonard J. Bond, Dan Barnard, Zhan Zhang, Lucas Koester

Aerospace Engineering Publications

Electronics operating at cryogenic temperatures play a critical role in future science experiments and space exploration programs. The Deep Underground Neutrino Experiment (DUNE) uses a cold electronics system for data taking. Specifically, it utilizes custom-designed Application Specific Integrated Circuits (ASICs). The main challenge is that these circuits will be immersed in liquid Argon and that they need to function for 20+ years without any access. Ensuring quality is critical, and issues may arise due to thermal stress, packaging, and manufacturing-related defects: if undetected, these could lead to long-term reliability and performance problems. This paper reports an investigation into non-destructive evaluation ...


Zeta Function Regularization And Its Relationship To Number Theory, Stephen Wang May 2021

Zeta Function Regularization And Its Relationship To Number Theory, Stephen Wang

Electronic Theses and Dissertations

While the "path integral" formulation of quantum mechanics is both highly intuitive and far reaching, the path integrals themselves often fail to converge in the usual sense. Richard Feynman developed regularization as a solution, such that regularized path integrals could be calculated and analyzed within a strictly physics context. Over the past 50 years, mathematicians and physicists have retroactively introduced schemes for achieving mathematical rigor in the study and application of regularized path integrals. One such scheme was introduced in 2007 by the mathematicians Klaus Kirsten and Paul Loya. In this thesis, we reproduce the Kirsten and Loya approach to ...


Designing Cryogenic Strain Device For 2d Materials, Jake Carter May 2021

Designing Cryogenic Strain Device For 2d Materials, Jake Carter

Mechanical Engineering Undergraduate Honors Theses

The Churchill lab working within the Physics Department at the University of Arkansas is working to create important quantum states including weak topological insulators (TIs) through the use of symmetry engineering and topological electronic states in two-dimensional (2D) crystals of WHM materials. Experimental results of these topological states have been obstructed due to the difficulty to perform controlled in situ strain. This project strives to create a mount to utilize a piezoelectric nanopositioner within cryostats achieving an in situ strain that creates the quantum states the lab is looking to observe. This report also examines the necessary equations to determine ...


Design And Control Of A Peristaltic Pump To Simulate Left Atrial Pressure In A Conductive Silicone Model, Jeremy Collins May 2021

Design And Control Of A Peristaltic Pump To Simulate Left Atrial Pressure In A Conductive Silicone Model, Jeremy Collins

Mechanical Engineering Undergraduate Honors Theses

According to the CDC, atrial fibrillation is responsible for more than 454,000 hospitalizations and approximately 158,000 deaths per year. A common treatment for atrial fibrillation is catheter ablation, a process in which a long flexible tube is guided through the femoral artery and to the source of arrhythmia in the heart, where it measures the electrical potential at various locations and converts problematic heart tissue to scar tissue via ablation. This paper details the design and control of a low-cost ($400) peristaltic pump system using repetitive control to replicate blood pressure in the left atrium in a conductive ...


The Effects Of Materials And Profiles Of Gratings On Diffraction Spectra, Brock Halling May 2021

The Effects Of Materials And Profiles Of Gratings On Diffraction Spectra, Brock Halling

Physics Capstone Projects

Diffraction patterns can be made either by transmitting or reflecting light from a grating which is an array of parallel lines (rulings) with a fixed periodicity. Elementary optical treatment of diffraction gratings only describes diffraction angles as a function of periodicity of the grating. However, we have observed that the profile and materials of the grating do affect the diffraction pattern. In this study, I investigated the correlation between the grating profiles obtained by scanning electron microscopy and the materials of the grating (polymer and silicon dioxide) and the spectra as a function of the diffraction angle. An optical spectrometer ...


Comparisons Of Mesospheric Temperatures Between 70 And 110 Km: Usu Lidar, Nasa's Timed Satellite, And The Msis2 Empirical Model, David M. Collins May 2021

Comparisons Of Mesospheric Temperatures Between 70 And 110 Km: Usu Lidar, Nasa's Timed Satellite, And The Msis2 Empirical Model, David M. Collins

Physics Capstone Projects

Earth’s atmosphere can be characterized by its temperature structure, dividing the atmosphere into natural discrete regions. The mesosphere (50 to ~100 km) has been the least studied. Rayleigh-scatter lidars (RSL) and rockets can obtain local, high-resolution measurements above one spot, while satellites looking almost horizontally obtain global measurements. These two methods of measuring atmospheric conditions are compared using the USU RSL and the SABER instrument on NASA’s TIMED satellite. These measurements were graphed to show four sets of temperatures from several sources in the atmospheric region 70 km to 110 km above USU. The results show similar temperatures ...


Curved Spacetime In The Causal Set Approach To Quantum Gravity, Ayush Dhital May 2021

Curved Spacetime In The Causal Set Approach To Quantum Gravity, Ayush Dhital

Honors Theses

Causal Set theory is an approach to quantum gravity. In this approach, the spacetime continuum is assumed to be discrete rather than continuous. The discrete points in a causal set can be seen as a continuum spacetime if they can be embedded in a manifold such that the causal structure is preserved. In this regard, a manifold can be constructed by embedding a causal set preserving causal information between the neighboring points. In this thesis, some of the fundamental properties of causal sets are discussed and the curvature and dimension information of Minkowski, de Sitter, and Anti-de Sitter spaces is ...


Developing Electron Beam Lithography At Nanoscale Device Laboratory, Din Pašić May 2021

Developing Electron Beam Lithography At Nanoscale Device Laboratory, Din Pašić

Physics Capstone Projects

At the Nanoscale Device Laboratory, we can routinely create patterns with a minimum linewidth of 800 nm using photolithography. However, to create photonic devices, the pattern size must be smaller than the wavelength of visible light (400 to 800 nm). Dedicated electron beam writers can achieve a sub-10 nm linewidth, but this system is beyond our reach. In this project, we plan to use a Nanometer Pattern Generation System connected to a Quanta 650 scanning electron microscope to perform e-beam lithography. After setting up a computer to run the NPGS system, and establishing communications with the SEM, we experimented with ...


Fundamental Aspects Of Black Holes, Jacob Fisher Ciafre May 2021

Fundamental Aspects Of Black Holes, Jacob Fisher Ciafre

All Graduate Plan B and other Reports

The literature study here seeks to present the foundations of black hole physics in General Relativity. The report includes a discussion of the Kerr black hole metric, black hole entropy, particle creation, the laws of black hole mechanics, and a bilinear mass formula for the Kerr-Newman black hole solution.


Simulation And Optimization Of Kinematics Measurements For The Moller Parity-Violating Electron-Electron Scattering Experiment, Lauren Carver May 2021

Simulation And Optimization Of Kinematics Measurements For The Moller Parity-Violating Electron-Electron Scattering Experiment, Lauren Carver

Undergraduate Honors Theses

This report describes the optimization of the sieve collimator that will be used for the MOLLER experiment at Jefferson Laboratory. The MOLLER experiment seeks to study the parity-violating asymmetry in electron-electron elastic scattering. For this project, Monte Carlo simulations were run using a GEANT4 simulation package, which includes the main geometry of the proposed experiment, and the essential physics reaction processes. A sieve collimator was added to the simulated geometry. This collimator has pin-hole openings to select scattered electrons at certain locations (radial and azimuthal positions) corresponding to specific scattering angles (theta, and phi). Analysis of the simulated data were ...


Composite Gravity In Curved Spacetime, Austin Batz May 2021

Composite Gravity In Curved Spacetime, Austin Batz

Undergraduate Honors Theses

This work presents the development of a quantum theory of gravity motivated by diffeomorphism-invariance and background-independence. A composite graviton state that satisfies the linearized Einstein’s field equations has been identified via perturbative expansion about a curved vacuum spacetime. The emergence of this gravitational interaction is discussed, as well as cancellation of tadpoles and treatment of ultraviolet divergences via dimensional regularization. In other words, the formalism of quantum field theory is used to identify a gravitational interaction as an emergent phenomenon rather than as a fundamental aspect of nature. The lattice is proposed as a candidate for a physical regulator ...


Topology Of The O(3) Non-Linear Sigma Model Under The Gradient Flow, Stuart Thomas, Christopher Monahan May 2021

Topology Of The O(3) Non-Linear Sigma Model Under The Gradient Flow, Stuart Thomas, Christopher Monahan

Undergraduate Honors Theses

Quantum field theory is an extraordinarily successful framework that describes phenomena in particle physics and condensed matter. The O(3) non-linear sigma model (NLSM) is a specific theory used in both of these fields, describing ferromagnets and acting as a prototype for the strong nuclear force. It features topologically stable configurations known as instantons which cannot continuously evolve to the ground state. The topological susceptibility is a parameter that describes this stability and is predicted to vanish in physical theories, however numerical simulations find that the topological susceptibility diverges in the continuum limit. This issue has motivated the application of ...