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Articles 1 - 30 of 488
Full-Text Articles in Physics
Reduced K+ Build-Up In T-Tubules Contributes To Resistance Of The Diaphragm To Myotonia, Jessica H. Myers, Kirsten Denman, Chris Dupont, Brent D. Foy, Mark M. Rich
Reduced K+ Build-Up In T-Tubules Contributes To Resistance Of The Diaphragm To Myotonia, Jessica H. Myers, Kirsten Denman, Chris Dupont, Brent D. Foy, Mark M. Rich
Physics Faculty Publications
Patients with myotonia congenita suffer from slowed muscle relaxation caused by hyperexcitability. The diaphragm is only mildly affected in myotonia congenita; discovery of the mechanism underlying its resistance to myotonia could identify novel therapeutic targets. Intracellular recordings from two mouse models of myotonia congenita revealed the diaphragm had less myotonia than either the extensor digitorum longus (EDL) or the soleus muscles. A mechanism contributing to resistance of the diaphragm to myotonia was reduced depolarization of the interspike membrane potential during repetitive firing of action potentials, a process driven by build-up of K+ in small invaginations of muscle membrane known as …
In-Situ Preparation Of Cofe2o4 Nanoparticles On Eggshell Membrane-Activated Carbon For Microwave Absorption, Hassan Soleimani, Jemilat Yetunde Yusuf, Lee Kean Chuan, Hojjatollah Soleimani, Mustapha Lutfi Bin Sabar, Andreas Öchsner, Zulkifly Abbas, Asmau Iyabo Balogun, Gregory Kozlowski
In-Situ Preparation Of Cofe2o4 Nanoparticles On Eggshell Membrane-Activated Carbon For Microwave Absorption, Hassan Soleimani, Jemilat Yetunde Yusuf, Lee Kean Chuan, Hojjatollah Soleimani, Mustapha Lutfi Bin Sabar, Andreas Öchsner, Zulkifly Abbas, Asmau Iyabo Balogun, Gregory Kozlowski
Physics Faculty Publications
This study explores the potential of using cobalt ferrite (CF) nanoparticles grown in situ on eggshell membranes (ESM) to mitigate the increasing problem of electromagnetic interference (EMI). A simple carbonization process was adopted to synthesize CF nanoparticles on ESM. The study further examines the composites' surface morphology and chemical composition and evaluates their microwave absorption performance (MAP) at X-band frequency. Results showed that the composite of CF and ESM - CESM@CF, exhibited a strong RL peak value of −39.03 mm with an optimal thickness of 1.5 mm. The combination of CF and ESM demonstrates excellent impedance matching and EM wave …
Direct Parameter Fitting Of Action Potentials In Skeletal Muscle Cells Which Include Longitudinal Segments, Tyme Suda
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Excitation of skeletal muscle cells triggers a large voltage spike known as an action potential (AP), leading to muscle contraction. Modeling of an AP is typically done using the method developed by scientists Hodgkin and Huxley (HH). In the HH method, voltage and time gated Na+ and K+ ionic currents are simulated, along with a positive “Leak” ionic current and capacitive current. Due to the complexity and the computational time required for simulation, direct fitting of HH parameters to experimental APs has rarely been attempted. A previous thesis at Wright State performed direct fitting for the case of a single …
A First Study Of The Effect Of Surface Roughness In Additive-Manufactured Copper At Thz Frequencies, Tomas Di Fulvio, Elliott R. Brown, Andrew J. Huebner, Michael A. Saville, Paul Sotirelis
A First Study Of The Effect Of Surface Roughness In Additive-Manufactured Copper At Thz Frequencies, Tomas Di Fulvio, Elliott R. Brown, Andrew J. Huebner, Michael A. Saville, Paul Sotirelis
Physics Faculty Publications
The surface roughness of additive-manufactured copper is characterized by profilometry, and its effect on the THz reflectance is measured at 600 GHz. A strong specular component is measured, as well as a non-specular component displaying fluctuations in the wings of the angular reflectance plot.
Submillimeter-Wave Cornea Phantom Sensing Over An Extended Depth Of Field With An Axicon-Generated Bessel Beam, Mariangela Baggio, Aleksi Tamminen, Joel Lamberg, Roman Grigorev, Samu-Ville Pälli, Juha Ala-Laurinaho, Irina Nefedova, Jean-Louis Bourges, Sophie X. Deng, Elliott R. Brown, Vincent P. Wallace, Zachary D. Taylor
Submillimeter-Wave Cornea Phantom Sensing Over An Extended Depth Of Field With An Axicon-Generated Bessel Beam, Mariangela Baggio, Aleksi Tamminen, Joel Lamberg, Roman Grigorev, Samu-Ville Pälli, Juha Ala-Laurinaho, Irina Nefedova, Jean-Louis Bourges, Sophie X. Deng, Elliott R. Brown, Vincent P. Wallace, Zachary D. Taylor
Physics Faculty Publications
The feasibility of a 220 - 330 GHz zero order axicon generated Bessel beam for corneal water content was explored. Simulation and experimental data from the 25-degree cone angle hyperbolic-axicon lens illuminating metallic spherical targets demonstrate a monotonically decreasing, band integrated, backscatter intensity for increasing radius of curvature from 7 - 11 mm, when lens reflector and optical axis are aligned. Further, for radii >= 9.5 mm, maximum signal was obtained with a 1 mm transverse displacement between lens and reflector optical axes arising from spatial correlation between main lobe and out of phase side lobes. Thickness and permittivity parameter …
Metal-To-Insulator Transition In An Anderson Insulator With Kondo Impurities, Weidong Zhang, Elliott R. Brown, Richard P. Mirin
Metal-To-Insulator Transition In An Anderson Insulator With Kondo Impurities, Weidong Zhang, Elliott R. Brown, Richard P. Mirin
Physics Faculty Publications
We report a voltage-controlled critical behavior observed in a GaAs epitaxial structure containing a dense array of ErAs nanoparticles. When fabricated with metal electrodes, the structure displays a voltage- and temperature-dependent metal-to-insulator transition and strong hysteresis in the current versus voltage and versus temperature characteristics, with critical temperatures as high as 77 K. Furthermore, we observed a diverging rms deviation of the electrical conductance with respect to the critical bias voltage, which further supports the existence of a phase transition. The insulating phase is governed by Efros-Shklovskii variable range hopping, and the conductance reduces beyond instrument limits as the temperature …
Electromagnetic Wave Absorption Of Coconut Fiber-Derived Porous Activated Carbon, Jemilat Yetunde Yusuf, Hassan Soleimani, Noorhana Yahya, Yekinni Kolawole Sanusi, Gregory Kozlowski, Andreas Öchsner, Lawal Lanre Adebayo, Fatai Adisa Wahaab, Surajudeen Sikiru, Bashiru Bolaji Balogun
Electromagnetic Wave Absorption Of Coconut Fiber-Derived Porous Activated Carbon, Jemilat Yetunde Yusuf, Hassan Soleimani, Noorhana Yahya, Yekinni Kolawole Sanusi, Gregory Kozlowski, Andreas Öchsner, Lawal Lanre Adebayo, Fatai Adisa Wahaab, Surajudeen Sikiru, Bashiru Bolaji Balogun
Physics Faculty Publications
In this study, porous carbon has been prepared through potassium hydroxide (KOH) activation of coconut fiber (CF) and subsequent carbonization in the presence of an inert gas. The activated carbons (AC) were prepared via carbonization of the precursor at different temperatures. Subsequently, their electromagnetic wave absorption (EMWA) performance was investigated at X-band frequency. The phase crystallinity, porous features, and degree of graphitization of the activated carbons were studied using XRD, nitrogen adsorption/desorption isotherm, and Raman spectroscopy, respectively. Using the BET method, the activated carbon prepared at 750 °C displayed a high specific surface area of 602.9 m2 g−1 and an …
Establishing A Machine Learning Framework For Discovering Novel Phononic Crystal Designs, Drew Feltner
Establishing A Machine Learning Framework For Discovering Novel Phononic Crystal Designs, Drew Feltner
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A phonon is a discrete unit of vibrational motion that occurs in a crystal lattice. Phonons and the frequency at which they propagate play a significant role in the thermal, optical, and electronic properties of a material. A phononic material/device is similar to a photonic material/device, except that it is fabricated to manipulate certain bands of acoustic waves instead of electromagnetic waves. Phononic materials and devices have been studied much less than their photonic analogues and as such current materials exhibit control over a smaller range of frequencies. This study aims to test the viability of machine learning, specifically neural …
The Role Of Action Potential Changes In Depolarization-Induced Failure Of Excitation Contraction Coupling In Mouse Skeletal Muscle, Xueyong Wang, Murad Nawaz, Chris Dupont, Jessica H. Myers, Steve R.A. Burke, Roger A. Bannister, Brent D. Foy, Andrew A. Voss, Mark M. Rich
The Role Of Action Potential Changes In Depolarization-Induced Failure Of Excitation Contraction Coupling In Mouse Skeletal Muscle, Xueyong Wang, Murad Nawaz, Chris Dupont, Jessica H. Myers, Steve R.A. Burke, Roger A. Bannister, Brent D. Foy, Andrew A. Voss, Mark M. Rich
Physics Faculty Publications
Excitation-contraction coupling (ECC) is the process by which electrical excitation of muscle is converted into force generation. Depolarization of skeletal muscle resting potential contributes to failure of ECC in diseases such as periodic paralysis, intensive care unit acquired weakness and possibly fatigue of muscle during vigorous exercise. When extracellular K+ is raised to depolarize the resting potential, failure of ECC occurs suddenly, over a narrow range of resting potentials. Simultaneous imaging of Ca2+ transients and recording of action potentials (APs) demonstrated failure to generate Ca2+ transients when APs peaked at potentials more negative than –30mV. An AP property that closely …
Investigation Of Thz Absorptive Signatures In Opioids, Weidong Zhang, Alexei Bykhovski, Elliott R. Brown
Investigation Of Thz Absorptive Signatures In Opioids, Weidong Zhang, Alexei Bykhovski, Elliott R. Brown
Physics Faculty Publications
We investigate the possibility of sensing opioid drugs, such as fentanyl, by their THz electromagnetic signatures. The methods include both computer modeling and experiments. Molecular dynamics simulations predict that fentanyl should display THz resonances, with several of them occurring below 1.0 THz; the lowest one is at around 0.337 THz (337 GHz). Spectroscopy measurements were conducted on oxycodone, which was used as a surrogate for fentanyl. They display vibrational absorption resonances between ∼1.4 and 1.6 THz.
The Effects Of An Ultrafast Pulsed Laser On Ybco Thin Film Circuit Transients, Matthew L. Rustad
The Effects Of An Ultrafast Pulsed Laser On Ybco Thin Film Circuit Transients, Matthew L. Rustad
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Terahertz (THz) frequency light has shown promise for a wide variety of applications due to its material characterization and imaging capabilities. Its nondestructive nature coupled with its submillimeter spatial resolution provides the most value for terahertz light as an imaging tool. The application of terahertz technology has been limited by a lack of novel and powerful sources. It has been shown that that Yttrium Barium Copper Oxide (YBCO), a type II superconductor, has certain properties that would allow YBCO to be an effective source for THz light. Recent microwave work has shown that when a persistent supercurrent is placed on …
Using Network Analysis To Contrast Three Models Of Student Forum Discussions, Hannah N. Benston
Using Network Analysis To Contrast Three Models Of Student Forum Discussions, Hannah N. Benston
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There is much research about how actors and events in social networks affect each other. In this research, three network models were created for discussion forums in three semesters of undergraduate general physics courses. This study seeks to understand what social network measures are most telling of a online forum classroom dynamic. That is, I wanted to understand more about things like what students are most central to the networks and whether this is consistent across different network models. I also wanted to better understand how students may or may not group together. What relationships (student to student, student to …
Experimental Measurement Of Sharp Thz Absorption Signatures From Nucleic Acid Solutions In Nanofluidic Channels, Elliott R. Brown, Edgar A. Mendoza
Experimental Measurement Of Sharp Thz Absorption Signatures From Nucleic Acid Solutions In Nanofluidic Channels, Elliott R. Brown, Edgar A. Mendoza
Physics Faculty Publications
We report on the room-temperature experimental measurement of THz absorption signatures in aqueous, double-stranded nucleic acid solutions confined to the submicron silica channels on fused quartz substrates using THz frequency-domain (photomixing) spectroscopy. Three sharp (i.e., strong and narrow) signatures, ~10–20 GHz FWHM, are observed in the shortest base pair sample—small interfering, double-stranded (ds) RNA—in the range of 800 GHz to 1.1 THz. Three similar signatures are also observed in a 50-bp dsDNA ladder sample. For a 1-kbp dsDNA ladder sample, the three are still evident, but are broadened and weakened. For a 48.5-kbp sample (λ-DNA), no prominent signatures are observed, …
Temperature Characterization Of Unipolar-Doped Electroluminescence In Vertical Gan/Aln Heterostructures, Weidong Zhang, Tyler A. Growden, Paul R. Berger, David F. Storm, David J. Meyer, Elliott R. Brown
Temperature Characterization Of Unipolar-Doped Electroluminescence In Vertical Gan/Aln Heterostructures, Weidong Zhang, Tyler A. Growden, Paul R. Berger, David F. Storm, David J. Meyer, Elliott R. Brown
Physics Faculty Publications
An electroluminescence (EL) phenomenon in unipolar-doped GaN/AlN/GaN double-barrier heterostructures—without any p-type contacts—was investigated from 4.2 K to 300 K. In the range of 200–300 K, the extracted peak photon energies agree with the Monemar formula. In the range of 30 to 200 K, the photon energies are consistent with A-exciton emission. At 4.2 K, the exciton type likely transforms into B-exciton. These studies confirm that the EL emission comes from a cross-bandgap (or band-to-band) electron-hole radiative recombination and is excitonic. The excitons are formed by the holes generated through interband tunneling and the electrons injected into the GaN emitter region …
Finite Different Time-Domain Simulation Of Terahertz Waves Propagation Through Unmagnetized Plasma, Aditha Srikantha Senarath
Finite Different Time-Domain Simulation Of Terahertz Waves Propagation Through Unmagnetized Plasma, Aditha Srikantha Senarath
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In order to support ongoing terahertz time-domain spectroscopic experiments involving plasma characterization, it is beneficial to simulate the interaction of THz pulses with varying plasma configurations. In this approach, a 1-D Finite Difference Time Domain (FDTD) model was constructed to simulate the interaction of terahertz radiation with a plasma medium. In order to incorporate the plasma properties into the simulation, a Z-transformation was applied. This model is capable of simulating the following properties of plasmas including electron density, collision frequency, and the interaction length of the plasma medium. The simulated model was characterized using terahertz time-domain spectroscopy. The effects of …
Flux Pinning Enhancements Of Yba2cu3o7-X With Nanosize Magnetic Additions, M. A. Sebastian, N. A. Pierce, I. Maartense, Gregory Kozlowski, T. J. Haugan
Flux Pinning Enhancements Of Yba2cu3o7-X With Nanosize Magnetic Additions, M. A. Sebastian, N. A. Pierce, I. Maartense, Gregory Kozlowski, T. J. Haugan
Physics Faculty Publications
Different methods of flux pinning are being tested world-wide to enhance critical currents (Ics) of high temperature superconductor YBa2Cu3O7-x (YBCO) coated conductors exposed to high magnetic fields. Magnetic materials are interesting to consider as flux pinning additions because of their potential for very strong pinning strength. To our knowledge, there have been limited demonstrations of magnetic pinning additions to YBCO conductors. This paper describes the study of different M magnetic phase additions to YBCO including M = BaFe12O19, La0.67Ca0.33MnO3, and other oxide phases. Nanosize additions were incorporated by depositing multilayer (M/YBCO)N films to minimize degradation of Tc, and testing volume …
Effects Of Growth Temperature On Electrical Properties Of Gan/Aln Based Resonant Tunneling Diodes With Peak Current Density Up To 1.01 Ma/Cm2, Evan M. Cornuelle, Tyler A. Growden, David F. Storm, Elliott R. Brown, Weidong Zhang, Brian P. Downey, Vikrant Gokhale, Laura B. Ruppalt, James G. Champlain, Prudhvi Peri, Martha R. Mccartney, David J. Smith, David J. Meyer, Paul R. Berger
Effects Of Growth Temperature On Electrical Properties Of Gan/Aln Based Resonant Tunneling Diodes With Peak Current Density Up To 1.01 Ma/Cm2, Evan M. Cornuelle, Tyler A. Growden, David F. Storm, Elliott R. Brown, Weidong Zhang, Brian P. Downey, Vikrant Gokhale, Laura B. Ruppalt, James G. Champlain, Prudhvi Peri, Martha R. Mccartney, David J. Smith, David J. Meyer, Paul R. Berger
Physics Faculty Publications
Identical GaN/AlN resonant tunneling diode structures were grown on free-standing bulk GaN at substrate temperatures of 760 ○C, 810 ○C, 860 ○C, and 900 ○C via plasma-assisted molecular beam epitaxy. Each sample displayed negative differential resistance (NDR) at room tem- perature. The figures-of-merit quantified were peak-to-valley current ratio (PVCR), yield of the device with room-temperature NDR, and peak current density (Jp). The figures-of-merit demonstrate an inverse relationship between PVCR/yield and Jp over this growth temperature series. X-ray diffraction and transmission electron microscopy were used to determine the growth rates, and layer thicknesses were used to explain the varying figures-of-merit. Due …
Development Of Embedded Atom Method Interatomic Potentials For Ge-Sn-Si Ternary And Constituent Binary Alloys For Modeling Material Crystallization, Sudip Acharya
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Group IV elements based nanoelectronics devices (mainly Si and Ge based devices) have been developed and improved over a long period of time and are the most influencing materials of semiconductor electronics, but due to their indirect bandgap their use in optoelectronics is limited. Alternatively, new Group IV alloys comprised of Ge, Si, and Sn semiconductor materials have emerged as attractive options for various electronic and optoelectronic applications. The binary and ternary alloys provide strain and energy bandgap engineering by controlling element content, a route for realizing direct-transition semiconductors, improvement in interface and defect properties, and a reduction of the …
One-Dimensional Kinetic Particle-In-Cell Simulations Of Various Plasma Distributions, Richard N. Vanderburgh
One-Dimensional Kinetic Particle-In-Cell Simulations Of Various Plasma Distributions, Richard N. Vanderburgh
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A one-dimensional kinetic particle-in-cell (PIC) MATLAB simulation was created to demonstrate the time-evolution of various plasma distributions. Building on previous plasma PIC programs written in FORTRAN and Python, this work recreates the computational and diagnostic tools of these packages in a more user- and educational-friendly development environment. Plasma quantities such as plasma frequency and species charge-mass ratios are arbitrarily defined. A one-dimensional spatial environment is defined by total length and number and size of spatial grid points. In the first time-step, charged particles are given initial positions and velocities on a spatial grid. After initialization, the program solves for the …
Evolution Of Electron Properties After Nanosecond Repetitively Pulsed Discharges In Air Measured By Thomson Scattering, Chase S. Murray
Evolution Of Electron Properties After Nanosecond Repetitively Pulsed Discharges In Air Measured By Thomson Scattering, Chase S. Murray
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This work was an investigation of nanosecond repetitively pulsed discharges in air by measuring the evolution of electron density and electron temperature between pulses using Thomson scattering of laser light. Bursts of repetitive pulses within several microseconds after the initial pulse were found to exhibit a coupling effect and create an even higher electron density than the initial pulse. The wide range of temperatures and densities of the electrons existing between pulses allow an opportunity to explore both the collective and non-collective regimes of Thomson scattering. By measuring electron density and temperature at a variety of times, an accurate description …
Characterization Of A Novel Terahertz Chemical Sensor, Daniel J. Tyree
Characterization Of A Novel Terahertz Chemical Sensor, Daniel J. Tyree
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A recently constructed novel analytical tabletop terahertz (THz) chemical sensor capable of detecting a wide range of gases with high sensitivity and specificity was characterized to assess its performance over a range of operational parameters. The sensor was designed with an objective of quantifying composition of exhaled human breath, where target concentrations span part per trillion (ppt) to part per billion (ppb) level of dilutions. The sensor utilizes terahertz rotational spectroscopy of sampled gases for quantification of dilutions. The sensor occupies a volume of ~ 2 ft3 and incorporates a coiled absorption cell, thermal desorption tubes, and all necessary electronic …
Methods For Registering And Calibrating In Vivo Terahertz Images Of Cutaneous Burn Wounds, Priyamvada Tewari, James Garritano, Neha Bajwa, Shijun Sung, Haochong Huang, Dayong Wang, Warren Grundfest, Daniel B. Ennis, Dan Ruan, Elliott Brown, Erik Dutson, Michael C. Fishbein, Zachary Taylor
Methods For Registering And Calibrating In Vivo Terahertz Images Of Cutaneous Burn Wounds, Priyamvada Tewari, James Garritano, Neha Bajwa, Shijun Sung, Haochong Huang, Dayong Wang, Warren Grundfest, Daniel B. Ennis, Dan Ruan, Elliott Brown, Erik Dutson, Michael C. Fishbein, Zachary Taylor
Physics Faculty Publications
A method to register THz and visible images of cutaneous burn wounds and to calibrate THz image data is presented. Images of partial and full thickness burn wounds in 9 rats were collected over 435 mins. = 7.25 hours following burn induction. A two-step process was developed to reference the unknown structure of THz imaging contrast to the known structure and the features present in visible images of the injury. This process enabled the demarcation of a wound center for each THz image, independent of THz contrast. Threshold based segmentation enabled the automated identification of air (0% reflectivity), brass (100% …
The Magnetocaloric Effect & Performance Of Magnetocaloric Materials In A 1d Active Magnetic Regenerator Simulation, Daniel Nicholas Bayer
The Magnetocaloric Effect & Performance Of Magnetocaloric Materials In A 1d Active Magnetic Regenerator Simulation, Daniel Nicholas Bayer
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Active magnetic regenerators (AMRs) operate according to the magnetothermal phenomenon known as the magnetocaloric effect (MCE), and are at the forefront of magnetic cooling technology. AMR simulations have been shown to be useful tools in predicting the performance of different magnetocaloric materials (MCMs) without the need to develop a physical prototype. In a search to determine the set of operational parameters which would maximize MCM performance, a 1D simulation of an AMR device has been developed in Matlab. Gadolinium, the most well-documented MCM, is used as a benchmark material to study the effects of varying certain operational parameters such as …
Sensitivity Limits Of Millimeter-Wave Photonic Radiometers Based On Efficient Electro-Optic Upconverters, Gabriel Santamaría Botello, Florian Sedlmeir, Alfredo Rueda, Kerlos Atia Abdalmalak, Elliott R. Brown, Gerd Leuchs, Sascha Preu, Daniel Segovia-Vargas, Dmitry V. Strekalov, Luis Enrique García Muñoz, Harald G.L. Schwefel
Sensitivity Limits Of Millimeter-Wave Photonic Radiometers Based On Efficient Electro-Optic Upconverters, Gabriel Santamaría Botello, Florian Sedlmeir, Alfredo Rueda, Kerlos Atia Abdalmalak, Elliott R. Brown, Gerd Leuchs, Sascha Preu, Daniel Segovia-Vargas, Dmitry V. Strekalov, Luis Enrique García Muñoz, Harald G.L. Schwefel
Physics Faculty Publications
Conventional ultra-high sensitivity detectors in the millimeter-wave range are usually cooled as their own thermal noise at room temperature would mask the weak received radiation. The need for cryogenic systems increases the cost and complexity of the instruments, hindering the development of, among others, airborne and space applications. In this work, the nonlinear parametric upconversion of millimeter-wave radiation to the optical domain inside high-quality (Q) lithium niobate whispering-gallery mode (WGM) resonators is proposed for ultra-low noise detection. We experimentally demonstrate coherent upconversion of millimeter-wave signals to a 1550 nm telecom carrier, with a photon conversion efficiency surpassing the state-of-the-art by …
Networks Identify Productive Forum Discussions, Adrienne L. Traxler, A. Gavrin, Rebecca Lindell
Networks Identify Productive Forum Discussions, Adrienne L. Traxler, A. Gavrin, Rebecca Lindell
Physics Faculty Publications
Discussion forums provide a channel for students to engage with peers and course material outside of class, accessible even to commuter and nontraditional populations. Forums can build classroom community and aid learning, but students do not always take up these tools. We use network analysis to compare three semesters of forum logs from an introductory calculus-based physics course. The networks show dense structures of collaboration that differ significantly between semesters, even though aggregate participation statistics remain steady. After characterizing network structure for each semester, we correlate students’ centrality—a numeric measure of network position—with final course grade. Finally, we use a …
Item-Level Gender Fairness In The Force And Motion Conceptual Evaluation And The Conceptual Survey Of Electricity And Magnetism, Rachel Henderson, Paul Miller, John Stewart, Adrienne L. Traxler, Rebecca Lindell
Item-Level Gender Fairness In The Force And Motion Conceptual Evaluation And The Conceptual Survey Of Electricity And Magnetism, Rachel Henderson, Paul Miller, John Stewart, Adrienne L. Traxler, Rebecca Lindell
Physics Faculty Publications
Gender gaps on the most widely used conceptual inventories created by physics education researchers have been extensively studied. Most of the research exploring the consistent gender gaps has been performed at the student level using the total evaluation score; less research has been performed examining these assessments at the item level and this research has been predominately restricted to the Force Concept Inventory (FCI). Many studies have identified subsets of FCI items as unfair to either men or women. An item is fair if men and women of equal ability in conceptual physics score equally on the item. This study …
High Power Generation Of Thz From 1550-Nm Photoconductive Emitters, A. Mingardi, W. D. Zhang, E. R. Brown, A. D. Feldman, T. E. Harvey, And R.P. Mirin
High Power Generation Of Thz From 1550-Nm Photoconductive Emitters, A. Mingardi, W. D. Zhang, E. R. Brown, A. D. Feldman, T. E. Harvey, And R.P. Mirin
Physics Faculty Publications
Two photoconductive emitters - one with a self-complementary square spiral antenna, and the other with a resonant slot antenna - were fabricated on a GaAs epilayer embedded with ErAs quantum dots. Driven with 1550 nm mode-locked lasers, ~117 μW broadband THz power was generated from the device with the spiral antenna, and ~1.2 μW from the device with resonant slot antenna. The optical-to-THz conversion is through extrinsic photoconductivity.
The Influence Of A Surface On Hysteresis Loops For Single-Domain Ferromagnetic Nanoparticles, Saad Alsari
The Influence Of A Surface On Hysteresis Loops For Single-Domain Ferromagnetic Nanoparticles, Saad Alsari
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The influence of surface effects on a hysteresis loop for single domain, ferromagnetic nanoparticles was examined. Theoretical equations were derived to describe the magnetic behavior of the domains and a MATLAB program was used to solve them. M-H curves were calculated for the case when a magnetic field is applied in the favorable magnetization direction (easy axis). In contrast, the calculations show there were no hysteresis loops when the magnetic field was applied perpendicular to the easy axis. Our studies showed how parameters of the surface such as a associated with saturation magnetization near the surface of nanoparticles and Ks …
Electromagnetic Properties Of Fractal Antennas, Jordan Jeffrey Ewing
Electromagnetic Properties Of Fractal Antennas, Jordan Jeffrey Ewing
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Finite element method analysis is used to conduct electromagnetic simulations to characterize fractal antennas. This work considers wire (1D) antennas such as the triadic Koch curve, zig zag, and quadratic Koch curve of varying heights, iterations, and cross-sectional areas. Carpet (2D) antennas, including the Sierpinksi carpet, of varying heights, iterations, and deterministic and stochastic iterations are analyzed. The antenna shapes were generated in MATLAB and then modeled with finite element analysis using COMSOL Multiphysics®. The focus of this study is to determine what role various fractal patterns and iterations have on the S11 return loss and far field radiation patterns. …
Gender Fairness Within The Force Concept Inventory, Adrienne L. Traxler, Rachel Henderson, John Stewart, Gay Stewart, Alexis Papak, Rebecca Lindell
Gender Fairness Within The Force Concept Inventory, Adrienne L. Traxler, Rachel Henderson, John Stewart, Gay Stewart, Alexis Papak, Rebecca Lindell
Physics Faculty Publications
Research on the test structure of the Force Concept Inventory (FCI) has largely ignored gender, and research on FCI gender effects (often reported as “gender gaps”) has seldom interrogated the structure of the test. These rarely crossed streams of research leave open the possibility that the FCI may not be structurally valid across genders, particularly since many reported results come from calculus-based courses where 75% or more of the students are men. We examine the FCI considering both psychometrics and gender disaggregation (while acknowledging this as a binary simplification), and find several problematic questions whose removal decreases the apparent gender …