Other Physics Commons^™

Quantitative Study Of The Energy Changes In Voltage-Controlled Spin Crossover Molecular Thin Films, Aaron Mosey, Ashley S. Dale, Guanhua Hao, Alpha T. N’Diaye, Peter Dowben, Ruihua Cheng

Peter Dowben Publications

Voltage-controlled nonvolatile isothermal spin state switching of a [Fe{H2B(pz)₂}₂(bipy)] (pz=tris(pyrazol-1-1y)-borohydride, bipy=2,2’-bipyridine) film, more than 40 to 50 molecular layers thick, is possible when it is adsorbed onto a molecular ferroelectric substrate. Accompanying this high spin and low spin state switching, at room temperature, we observe a remarkable change in conductance, thereby allowing not only non-volatile voltage control of the spin state (“write”), but also current sensing of the molecular spin state (“read”). Monte Carlo Ising model simulations of the high spin state occupancy, extracted from x-ray absorption spectroscopy, indicate that the energy difference between the low …

Ferroelectric Domain Wall Memristor, James P. V. Mcconville, Haidong Lu, Bo Wang, Yueze Tan, Charlotte Cochard, Michele Conroy, Kalani Moore, Alan Harvey, Ursel Bangert, Long-Qing Chen, Alexei Gruverman, J. M. Gregg

Alexei Gruverman Publications

A domain wall-enabled memristor is created, in thin film lithium niobate capacitors, which shows up to twelve orders of magnitude variation in resistance. Such dramatic changes are caused by the injection of strongly inclined conducting ferroelectric domain walls, which provide conduits for current flow between electrodes. Varying the magnitude of the applied electric-field pulse, used to induce switching, alters the extent to which polarization reversal occurs; this systematically changes the density of the injected conducting domain walls in the ferroelectric layer and hence the resistivity of the capacitor structure as a whole. Hundreds of distinct conductance states can be produced, …

2d Confinement Of Thermal Gradients In Metallic Non-Local Spin Valves, Rachel K. Bennet

Electronic Theses and Dissertations

Non-local spin valves (NLSVs) are a valuable tool in the growing field of spintronics due to their unique ability to separate charge current from pure spin current. Their potential applications as read heads for hard-disk drives, as well as use as logic gates and other spin sensors, makes detailed understanding of their behavior under a wide range of operating conditions very important.

In this dissertation, I present results of extreme thermal engineering of the supporting substrate of NLSVs, which has a dramatic impact on the background signal of the device as well as contributions from thermal spin effects such as …

The Physics Ph.D. Program, University Of Arkansas, Semicentennial Celebration, Rajendra Gupta

Physics Faculty Publications and Presentations

The Ph.D. program in physics at the University of Arkansas was established in 1959. The Department celebrated the program's semicentennial on October 16, 2009 by organizing a symposium and a banquet honoring the faculty who played important roles in starting and nurturing the program. This booklet presents a brief history of the Ph.D. program and an archival record of the celebration.

The Design Of A New Vaginal Applicator For Direction Modulated Brachytherapy (Dmbt) Using Geant4 Monte Carlo Simulation Code, Moeen Meftahi

Theses and Dissertations

Purpose: Anisotropy of the 192Ir source causes a lack of dose coverage at the apex in HDR vaginal cylinder brachytherapy (VC BT). In this study, we took advantage of the GEANT4 Monte Carlo (MC) simulation code to design a new DMBT vaginal applicator so that it maintains the dose coverage of the current vaginal cylinder at periphery everywhere while improving the apex coverage. In addition, since current treatment planning systems (TPS) considers the whole environment as water according to TG43 formalism, based on the capability of the MC in the calculation of dose in the material, the effect of inhomogeneity …

Stacked Volume Holographic Gratings For Extending The Operational Wavelength Range In Led And Solar Applications, Sanjay Keshri, Julia Marín-Sáez, Izabela Naydenova, Kevin Murphy, Jesús Atencia, Daniel Chemisana, Sean Garner, María-Victoria Collados, Suzanne Martin

Articles

A novel stacking procedure is presented for volume phase holographic gratings (VPHGs) recorded in photopolymer material using Corning Willow Glass as a flexible substrate in order to achieve broader angular and spectral selectivity in a diffractive device with high efficiency for solar and LED applications. For the first time to our knowledge, we have shown a device designed for use with a white LED that has the same input and output angles and high efficiency when illuminated by different wavelengths. In this paper, two VPHGs were designed, experimentally recorded, and tested when illuminated at normal incidence. The experimental approach is …

Question 1: Coffee Consumption; Question 2: Active Volcanoes, Lawrence Weinstein

Physics Faculty Publications

This article presents questions related to Fermi which include how much coffee U.S. scientists consume daily, and how many active volcanoes there are in the world.

Optimizing Measurement Strengths For Qubit Quasiprobabilities Behind Out-Of-Time-Ordered Correlators, Razieh Mohseninia, José Raúl González Alonso, Justin Dressel

Mathematics, Physics, and Computer Science Faculty Articles and Research

Out-of-time-ordered correlators (OTOCs) have been proposed as a tool to witness quantum information scrambling in many-body system dynamics. These correlators can be understood as averages over nonclassical multitime quasiprobability distributions (QPDs). These QPDs have more information and their nonclassical features witness quantum information scrambling in a more nuanced way. However, their high dimensionality and nonclassicality make QPDs challenging to measure experimentally. We focus on the topical case of a many-qubit system and show how to obtain such a QPD in the laboratory using circuits with three and four sequential measurements. Averaging distinct values over the same measured distribution reveals either …

Detection Of Whale Acoustic Signals In The Northern Gulf Of Mexico Ladc-Gemm Database, Yingxue Gao

LSU New Orleans Theses and Dissertations

Low-pass Fourier filter, wavelet filter, as well as matched filter detection methods were used to detect baleen whale signals in northern Gulf of Mexico data collected by the Littoral Acoustic Demonstration Center (LADC) consortium. Some potential low frequency signals appeared on the matched filter output figure. The shape of the signals is in line with one of the typical signal shapes of fin whales--vertical down-sweeps with 18s-time interval. Another shape of the signals is in line with one of the call type shapes of Bryde's whales--down-sweeps with 7s-time interval. A high-pass Fourier filter was also used to find toothed whale …

Pressure Driven Electronic Band Gap Engineering In Tin(Iv)-O,N Compounds, Daniel Thomas Sneed

UNLV Theses, Dissertations, Professional Papers, and Capstones

The intrinsic link between long-range order, coordination geometry, and the electronic properties of a system must be understood in order to tailor function-specific materials. Although material properties are typically tailored using chemical dopants, such methods can cause irreversible changes to the structure, limiting the range of functionality. The application of high pressure may provide an alternative “clean” method to tune the electronic properties of semiconducting materials by tailoring their defect density and structure.

We have explored a number of optoelectronic relevant materials with promising characteristics, specifically Sn-(O,N) compounds which have been predicted to undergo pressure-mediated opening of their optical band …

Stability Of A Regular Black Holes Thin-Shell Wormhole In Reissner-Nordstrom - De Sitter Space-Time, A. Eid

Applications and Applied Mathematics: An International Journal (AAM)

The dynamics regular black holes thin shell wormhole with a phantom energy equation of state in Reissner-Nordstrom - De sitter space-time is studied using the Darmois-Israel formalism. A mechanical stability analysis is carried out by using the standard perturbation method. The stable and unstable static solution depends on the suitable value of parameters.

Cyclic Kite Configuration With Variable Mass Of The Fifth Body In R5bp, Abdullah A. Ansari, Ashraf Ali, Mehtab Alam, Rabah Kellil

Applications and Applied Mathematics: An International Journal (AAM)

This paper presents a numerical investigation on some characteristics and parameters related to the motion of an infinitesimal body with variable mass in five-body problem. The other four bodies are considered as primaries. The whole system forms a cyclic kite configuration and moves on a circle, the center of which is taken as the origin.We assume that the motion of the fifth infinitesimal body is affected by the other components of the system but it has no effect on their behavior. We started by setting the equations of motion of the fifth body by using Jeans’ law and Meshcherskii’s space-time …

Application Of Reduced Differential Transform Method For Solving Two-Dimensional Volterra Integral Equations Of The Second Kind, Seyyedeh R. Moosavi Noori, Nasir Taghizadeh

Applications and Applied Mathematics: An International Journal (AAM)

In this paper, we propose new theorems of the reduced differential transform method (RDTM) for solving a class of two-dimensional linear and nonlinear Volterra integral equations (VIEs) of the second kind. The advantage of this method is its simplicity in using. It solves the equations straightforward and directly without using perturbation, Adomian’s polynomial, linearization or any other transformation and gives the solution as convergent power series with simply determinable components. Also, six examples and numerical results are provided so as to validate the reliability and efficiency of the method.

Foreword To Relativizing Newton, Vernon L. Smith

Economics Faculty Books and Book Chapters

A foreword to Ramzi Suleiman's book Relativizing Newton.

The Variability Of High-Frequency Motions And Their Interactions With The Mesoscale On The Mississippi Shelf, Jordan Earls

Master's Theses

In this study, we examine the spatial and temporal variability of high-frequency and low-frequency motions across the Mississippi Shelf and how the high-frequency motions are modulated by low-frequency mesoscale motions. For this purpose, we use Acoustic Doppler Current Profiler (ADCP) measurements collected at nearshore (23 m), mid-shelf (60 m), and shelf break (88 m) stations. High-frequency motions are defined as motions with periods less than 36 hours, whereas mesoscale motions have larger periods. The collected datasets are analyzed through bandpass filtering, least square harmonic analysis, spectral analysis, and empirical orthogonal functions (EOF). We find that along-shelf barotropic mesoscale motions contain …

First-Principles Simulations Of Materials Under Extreme Conditions, Kien Nguyen Cong

USF Tampa Graduate Theses and Dissertations

The investigation of materials at extreme conditions of high pressure and temperature (high-PT), has been one of the greatest scientific endeavors in condensed mater physics, chemistry, astronomy, planetary, and material sciences. Being subjected to high-PT conditions, materials exhibit dramatic changes in both atomic and electronic structure resulting in an emergence of exceptionally interesting phenomena including structural and electronic phase transitions, chemical reactions, and formation of novel compounds with never-previously observed physical and chemical properties. Although new exciting experimental developments in static and dynamic compression combined with new diagnostics/characterization methods allow to uncover new processes and phenomena at high P-T conditions, …

Using Natural Phenomena To Study The Ionosphere, Joseph Benjamin Malins

Physics & Astronomy ETDs

This dissertation explores novel techniques for observing the ionosphere using natural signals. The ionosphere is a region of plasma hundreds of kilometers above the Earth that affects communication and remote sensing applications across the world. Traditional techniques for observing the ionosphere involve using man made radio signals, either to reflect the signal at HF frequencies or to pass several signals through the ionosphere and compare the difference the ionosphere makes in the signals. However, such techniques are limited by the ability of equipment to produce these signals and by the numerous laws and regulations governing transmission of signals in the …

Electromagnetic Analysis Of Bidirectional Reflectance From Roughened Surfaces And Applications To Surface Shape Recovery, Julian Antolin Camarena

Physics & Astronomy ETDs

Scattering from randomly rough surfaces is a well-established sub area of electrodynamics. There remains much to be done since each surface and optical processes that may occur in within the scattering medium, and countless other scenarios, is different. There are also illumination models that describe lighting in a scene on the macroscopic scale where geometrical optics can be considered adequate. Of particular interest for us is the intersection of the physical scattering theories and the illumination models. We present two contributions: 1) A minimum of two independent images are needed since any opaque surface can be uniquely specified in terms …

High Power And Optomechanics In Advanced Ligo Detectors, Terra Christine Hardwick

LSU Doctoral Dissertations

In September 2015, a new era of astronomy began with the first direct detection of grav- itational waves from a binary black hole coalescence. The event was captured by the Laser Interferometer Gravitational-wave Observatory, comprised of two long-baseline interferometers, one in Livingston, LA and one in Hanford, WA. At the time of the first detection, the interferometers were part way through an upgrade to an advanced configuration and were operating with a strain sensitivity of just better than 10⁻²³/Hz^1/2 around 100Hz. The full Advanced LIGO design calls for sensitivity of a few parts in 10⁻²⁴/Hz …

Planck's And Callendar's Blackbody Radiation Formulas And Their Fitness To Experimental Data, Max Tran

Publications and Research

In this paper, we compare the blackbody radiation density formula obtained with classical physics by Hugh L Callendar and the formula obtained by Max Planck using quantization of energy. We use R and Maxima to analyze their fitness on coordinating experimental data and indicate some limitations with experiments in this area.