Physics Commons^™

Shadows Of A Schwarzschild Black Hole Surrounded By A Spherically Symmetric Dark Matter, Ahmad Ibrahim

Theses and Dissertations

In this thesis, using general relativity, the null geodesics and black hole shadow of a spherically symmetric configuration of a black hole (surrounded by a dark matter shell) are studied. First, the standard

results of the photon sphere of Schwarzschild de-Sitter black hole is revisited and analyzed more carefully. Secondly, using an ansatz (piecewise metric function) commonly used in the literature to describe the mass distribution of the spherically symmetric black hole - dark matter configuration, the null geodesics through vacuum and dark matter are analyzed. Assuming an observer located at a finite distance from the black hole outside the dark ...

Symmetries, Zero Modes And Light Transport In Non-Hermitian Photonics, Jose David Hernandez Rivero

Dissertations, Theses, and Capstone Projects

We approach some fundamental aspects of photonic dissipative systems treated by a non-Hermitian theory. Inspired by the possibilities provided by some major non-Hermitian symmetries, we study systematically the properties of the novel pseudochirality, pseudo-anti-Hermiticity, and supersymmetry. We analyze other aspect of photonics, the zero mode, which has a profound connection to non-Hermitian physics. We propose a scheme to realize a zero mode that exists even in the absence of symmetries. Finally, we approach light transport in non-Hermitian photonic systems, where the introduction of gain and loss can modify drastically the propagation speed of wavepackets.

Phase Transitions, Critical Phenomena, And Correlation Functions In The 2d Ising Model And Its Applications To Quantum Dynamics: A Tensor Network Approach, Sankhya Basu

Dissertations, Theses, and Capstone Projects

This thesis explores several aspects of the 2D Ising Model at both real and complex temperatures utilizing tensor network algorithms. We briefly discuss the importance of tensor networks in the context of forming efficient representations of wavefunctions and partition functions for quantum and classical many-body systems respectively, followed by a brief review of the tensor network renormalization algorithms to compute the one point and two point correlation functions. We use the Tensor Renormalization Group (TRG) to study critical phenomena and examine feasibility of accurate estimations of universal critical data for three critical points for three critical points in two dimensions ...

Optical Studies Of Wide Bandgap Photonic Materials, Nikesh Maharjan

Dissertations, Theses, and Capstone Projects

In this dissertation work, optical properties of wide bandgap materials such as hexagonal Boron Nitride (h-BN) and Zinc Oxide (ZnO) have been studied. Deep UV photoluminescence spectroscopy was employed to study the optical properties of bulk h-BN and powder crystals using a laser of wavelength 200 nm, which is the fourth harmonic of Ti:Sapphire laser as excitation source. The properties and chemical compositions of annealed and unannealed bulk h-BN were investigated. The PL spectra from h-BN samples annealed at 900 ºC in ambient air, had strong phonon assisted band edge emissions along with a sharp atomic-like emission line at ...

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 TPS_CS and ...

Implementation Of A Least Squares Method To A Navier-Stokes Solver, Jada P. Lytch, Taylor Boatwright, Ja'nya Breeden

Rose-Hulman Undergraduate Mathematics Journal

The Navier-Stokes equations are used to model fluid flow. Examples include fluid structure interactions in the heart, climate and weather modeling, and flow simulations in computer gaming and entertainment. The equations date back to the 1800s, but research and development of numerical approximation algorithms continues to be an active area. To numerically solve the Navier-Stokes equations we implement a least squares finite element algorithm based on work by Roland Glowinski and colleagues. We use the deal.II academic library , the C++ language, and the Linux operating system to implement the solver. We investigate convergence rates and apply the least squares ...

Contributions Of Vibrational Spectroscopy To Virology: A Review, Iqra Chaudhary, Naomi Jackson, Denise Denning, Luke O'Neill, Hugh Byrne

Articles

Vibrational spectroscopic techniques, both infrared absorption and Raman scattering, are high precision, label free analytical techniques which have found applications in fields as diverse as analytical chemistry, pharmacology, forensics and archeometrics and, in recent times, have attracted increasing attention for biomedical applications. As analytical techniques, they have been applied to the characterisation of viruses as early as the 1970s, and, in the context of the coronavirus disease 2019 (COVID-19) pandemic, have been explored in response to the World Health Organisation as novel methodologies to aid in the global efforts to implement and improve rapid screening of viral infection. This review ...

Editorial Board

Karbala International Journal of Modern Science

No abstract provided.

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 ...

Engineering Of A Multi-Epitope Subunit Vaccine Against Sasrs-Cov-2 Through The Viroinformatic Approach, Aamir Shehzada, Christijogo Sumartono, Jusak Nugraha, Helen Susilowatid, Andi Yasmin Wijayab, Hafiz Ishfaq Ahmad, Wiwiek Tyasningsih, Fedik Abdul Rantam

Karbala International Journal of Modern Science

The COVID-19 outbreak has infected millions of people worldwide, but no vaccine has been discovered to combat it efficiently. This research aims to design a multi-epitope vaccine using highly efficient B- and T-cell epitopes from the SARS-CoV-2 Surabaya isolate through a viroinformatic approach. First, the putative epitopes were linked together to develop tertiary structures and then docked with toll-like receptor 4 (TLR-4) that demonstrated a robust interaction with a low eigenvalue of 4.816138 e-06. Furthermore, the structure's high immunogenic response was observed and successfully cloned into the expression vector pET28a (+). This implies that the designed vaccine can prove ...

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 ...

Smart Grid Control: Demand Side Management In Household Refrigerators As A Tool For Load Shifting, Anogh Utkalika Zaman, James Doyle

Macalester Journal of Physics and Astronomy

With improved supply of renewable sources of energy the focus has shifted away from simply producing clean energy to efficient consumption of energy. Until cheaper methods of energy storage are developed, Demand Side Management (DSM) is the best option for maximising energy efficiency. This paper proposes a method of turning regular refrigerators into smart demand response fridges. First, we develop an algorithm that accounts for small fluctuations in price and switches the device for optimal performance and lowered running cost. Then, we use longer price fluctuations to predict suitable times for pre-cooling and investigate the reduction in price as a ...

Twisting Lasers With The Faraday Effect, Harrison Werrell

Macalester Journal of Physics and Astronomy

Our objective with this project was to create a system and procedure to quantify the magnetization of a material with polarized light by using the Faraday Effect, where the light is rotated according to the magnetization. This type of system has seen use in technologies such as magneto-optical drives and optical isolators, and is part of the study of optical materials, along with the similar MagnetoOptical Kerr Effect. Our system, specifically, is intended to be used as part of an advanced Physics Lab in the future. It uses an electromagnet to magnetize a sample, and a laser to observe the ...

Electrical Analysis Of A Pem Electrolysis Cell, Joey Wehrley, James Doyle

Macalester Journal of Physics and Astronomy

Polymer Electrolyte Membrane (PEM) electrolysis is a form of electrolysis that is heavily used in commercial capacities. It functions by using a membrane and an electric charge in order to perform electrolysis water, splitting it into its component parts - Hydrogen and Oxygen. These parts can then be used in a number of different applications, including reversing the electrolysis process to regenerate some energy in the form of electricity. During this experiment, multiple currents were run through a PEM cell, and voltages across the membrane were measured. It was found that a standard R/C charging model can be fit to ...

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 ...

Neutrino Oscillations In The Presence Of A Magnetic Field, Chinhsan Sieng

Macalester Journal of Physics and Astronomy

We calculate oscillation probabilities in the presence of an external magnetic field in a one-generation neutrino framework that includes both Majorana and Dirac mass terms. First, we write down the Euler-Lagrange equations and obtain a system of eight differential equations coupling together eight different neutrino states that can be distinguished by helicity, chirality, and particle/antiparticle-ness. We then solve this system of differential equations in various special cases, exhibiting different types of oscillations. When the magnetic field is in the direction of momentum, there are only four oscillation channels as helicity flip is forbidden. We observe that chirality flips are ...

The Impact Of Initial Abundances On Modeling The Weak S-Process, Lev S. Serxner

Macalester Journal of Physics and Astronomy

No abstract provided.

The Survey Of Hi In Extremely Low-Mass Dwarfs: New Results From Vla Imaging, Francesco Pecere, John M. Cannon, Damen Beverlin, Jackson Codd

Macalester Journal of Physics and Astronomy

We present new HI spectral line imaging of 19 galaxies in the “Survey of HI in Extremely Low-mass Dwarfs” (SHIELD) acquired for Large Program VLA/ 20A-330. Using the National Radio Astronomy Observatory’s Karl G. Jansky Very Large Array (VLA) in the C configuration, we produce images of the neutral interstellar medium (HI) on angular scales of 15 to 20 arcseconds (corresponding to physical resolutions of 200 to 1100 parsecs). The three-dimensional cubes probe the morphology and kinematics of the gas at a range of spatial and spectral resolutions. The cubes were collapsed to produce two-dimensional moment maps (representing HI ...

Hunting For Fast Radio Bursts From Messier 82: Exploring The Frb--Magnetar Connection, Susie Paine

Macalester Journal of Physics and Astronomy

Fast radio bursts (FRBs) are short-duration radio pulses of cosmological origin. Among the most common sources predicted to explain this phenomenon are bright pulses from a class of extremely highly magnetized neutron stars known as magnetars. In 2020, a Galactic magnetar produced an FRB-like burst, allowing researchers to constrain the Galactic magnetar burst rate. We assume that the magnetar burst rate scales with star formation rate and test an important prediction for similar bursts in nearby galaxies. Messier 82 (M82) has a star formation rate 40 times that of the Milky Way, implying that the magnetar burst rate would be ...

Finite-Difference-Time-Domain Simulation Of Ultrafast Experiments, Alpha Ma

Macalester Journal of Physics and Astronomy

The Finite-Difference-Time-Domain (FDTD) method is a numerical method that calculates electric fields or magnetic fields by interleaving them in space and time. Using a python package called “MEEP”, I was able to write optical simulations of ultrafast experiments, especially the Terahertz Pump-Probe experiments. The goal of this project was to use FDTD simulation to measure the transmission of an electro-magnetic pulse passing through a thin film of conducting material on a dielectric substrate in order to study the characteristic conductivity of potential solar cell materials.