Bulletin of the American Physical Society
2019 Annual Spring Meeting of the APS Ohio-Region Section
Volume 64, Number 7
Friday–Saturday, March 29–30, 2019; The College of Wooster in Wooster, Ohio
Session C01: Poster Session |
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Room: Ruth W. Williams Hall 140 |
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C01.00001: Correlation of hatchling mass and egg volume in extant birds from $\textit{Archilochus colubris}$ to $\textit{Struthio camelus}$ Scott Lee, Max Cooley, Joshua Thomas, Richard Irving Observations suggest that the birds hatch when they are near the maximum size that can be contained in their egg. In order to test this hypothesis, we have measured the volume of eggs of nineteen bird species from \textit{Archilochus colubris} (the ruby-throated hummingbird) to \textit{Struthio camelus} (the ostrich). The hatchling mass of these birds vary by more than three orders of magnitude. The volume of the eggs were measured by using scaled pictures of the eggs. The OpenCV library, and a custom python code was used to detect the edges of the eggs. We assumed the images were taken at right angles to the eggs, and that the eggs have cylindrical symmetry around the long axis. The points along the edges of the egg were fit with a polynomial to avoid resolution-induced calculation issues. The surface area and volume were calculated as if the points were a solid of revolution. Our method reproduces the volumes of ellipsoids with known dimensions with errors of less than 1{\%}. The hatchling mass is found to depend on the egg volume via a power law with an exponent of 1.01 (standard deviation $=$ 0.04), in support of the hypothesis. This relationship predicts a hatchling mass of 8.0 kg for the extinct \textit{Aepyornis maximus} (the giant elephant bird), the largest known bird for which intact eggs exist. [Preview Abstract] |
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C01.00002: Effects of high hydrostatic pressure on cellular respiration monitored using phasor analysis of UV-excited autofluorescence Martin Heidelman, Andrew I. Rodriguez, Max Kreider, Paul Urayama Pressure is known to affect many biological systems, including the structure and function of cellular membranes. Processes relying on membrane function, such as oxidative phosphorylation and cellular respiration, are sensitive to pressure. Here, we present results involving the real-time spectroscopic monitoring of cellular metabolism at high hydrostatic pressure (up to 40 MPa) using a micro-perfusion system capable of switching between two fluid reservoirs without depressurization. UV-excited cellular autofluorescence from reduced nicotinamide adenine dinucleotide (NADH) serves as the optical biomarker for the metabolic state of the sample with biophysical information contained in the spectral shape and intensity of the autofluorescence signal. Spectral shape is quantified using spectral phasor analysis. First, the cell's metabolic response to high pressure alone is characterized by cycling the pressure of the sample and examining the spectroscopic change. Results suggest that pressure-induced respiratory inhibition departs from a two-component behavior upon pressure cycling. Next, we compare this to chemically-induced respiratory inhibition (e.g., using ethanol and cyanide), allowing the effects of pressure to be further investigated. [Preview Abstract] |
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C01.00003: Study on the Physical and Biochemical Properties of Natural Antioxidant Polyphenols Hayoung Kyung, Chaewon Seo Recent studies have shown that oxidative stress, caused by an excess of the Reactive Oxygen Species (ROS) such as superoxide anion and hydrogen peroxide in the skin, is involved in the pathogenesis of this dermal disease. Epidemiological studies have shown ultraviolet (UV) radiation causes excessive induction of inflammation and oxidative stress. This causes, in turn, skin diseases including premature aging of the skin and gene damage, which is directly linked with skin cancers. In this paper, to inhibit or retard the process of these harmful chain reaction in the UV-exposed skin, study on the chemoprevention using chemopreventive agents, such as plant polyphenols that can inhibit the process was conducted. The chemical and physical properties of the polyphenols that may be useful for skin diseases associated with solar UV radiation-induced inflammation and oxidative stress were analyzed. Using computational programs, various information was extracted about molecules of polyphenols with functional groups. Optimization energies (kJ/mol) of the molecules were found and used to determine the characteristics and stability of the molecules while dipole moments (D) were used to determine the reactivity of the molecules. [Preview Abstract] |
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C01.00004: Propagation of light-sensitive reaction-diffusion waves in inhomogeneously illuminated systems Daniel Blaikie, Spencer Kirn, Niklas Manz The propagation dynamics of reaction-diffusion (RD) waves in illuminated quasi-2-dimensional systems was investigated, using various light-sensitive chemical Belousov-Zhabotinsky (BZ) reactions. Illuminating the BZ waves from below with visible light with a checkerboard pattern was used to change the light intensity in a repeating pattern, thus changing the speed of the light-sensitive waves. In our system, BZ waves slow down at higher illumination levels. Using a Ruthenium based catalyst, a light-sensitive BZ solution was made and absorbed by a filter paper to create the quasi-2D system. As the wave propagated over the checkerboard pattern of the illuminated system, the changes in speed would cause the wave to curve forward (dark area) and backward (bright area). The curvature should alternate and increase the overall speed of the wave as shown numerically by Schebesch and Engel in Phys.~Rev.~E \textbf{60}(6) 1999. We used various catalysts, light intensities, illumination patterns, and BZ-component concentrations to determine how different excitation waves propagate through non-homogeneous excitation pattern. [Preview Abstract] |
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C01.00005: Bioimaging Analysis Using Physical and Computational Simulations Richard Kyung, Seung Jun Lee Magnetic Resonance Imaging is a commonly used technique that produces an image of the subject’s anatomy through radio waves, magnetism and computers. The data for the image is first transmitted into a k-space diagram, which is changed into an image through the Fourier Transformation. In the paper, various filter functions were tested using the a computer program as low pass filters. All types of functions showed their distinct features and were compared to one another. Finally, taking many factors into account, an efficient new filter was proposed and tested. While filters were applied on the full K-space in order to find a most efficient filter, which can be used to produce best MRI image, a nonconventional approach was used in the image analysis. Original MRI image domain was transformed into k-space using Fourier Transform to determine an efficient filter that will produce optimal image. The proposed filters were different from the rectangular (square) function, Gaussian function, and circle function, but trial and error were done on the new filter to have all the advantages or properties of the old functions. [Preview Abstract] |
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C01.00006: Optical and Dielectric Constants of Organic-Inorganic Metal Halide Perovskites Thin Films Travis Maenle, Khagendra Bhandari Understanding of the complex dielectric function (refractive index) of MAPbI$_{\mathrm{3}}$ (CH$_{\mathrm{3}}$NH$_{\mathrm{3}}$PbI$_{\mathrm{3}})$ perovskite thin film is essential for designing photovoltaic devices, light emitting diodes and lasers. Keeping this in mind, the complex dielectric functions of MAPbI$_{\mathrm{3}}$ thin films at room temperature are investigated using optical reflectance spectra of perovskite thin films. The optical reflectance spectra are measured over the energy range of 1.24 eV to 4.13 eV. The phase $\theta (\omega )$ of the reflected wave is computed using the Kramers-Kronig dispersion relation between the real and imaginary parts of the complex function. Our results show that the absorption coefficient ($\alpha )$, refractive indices (n,$\kappa )$, real and imaginary components of the dielectric constants ($\varepsilon _{\mathrm{1}}$, $\varepsilon_{\mathrm{2}})$ of the MAPbI$_{\mathrm{3}}$ thin films are basically independent of the thicknesses of the films. We also compare $\alpha $ with experimentally calculated result. Our results agree well with previously reported results of the absorption coefficient and are consistent with Kramers-Kronig transformations. [Preview Abstract] |
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C01.00007: Spectral Stability of Gravitationally Interacting Rods Carlos Owusu-Ansah, John Linder We investigate the spectral stability of equilibrium configurations of two line-masses (slashes or rods) interacting via gravity. The Euler-Lagrange formalism provides the equations of motion. We determine the positions, orientations and angular velocities of the slashes at their equilibrium configurations. All equilibrium solutions are checked using the equations of motion. The spectral stability of each equilibrium configuration is determined by linearizing the equations of motion about the equilibrium configurations and analyzing the path of the slashes when they are perturbed. We illustrate the parameter values that cause equilibrium configurations to be spectrally stable. [Preview Abstract] |
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C01.00008: Speckle Interferometry of Close Visual Binary Star Systems Darin Mumma Roughly two-thirds of all stars in the observable universe are binary stars. Among these, close visual binary systems are those binaries whose apparent angular separation is between 1 and 10 arcseconds. Previously, these systems could only be analyzed with ordinary optical techniques that require large (3 meters or more) telescopes to resolve. This requirement has placed visual binary observations well out of reach of independent observatories, and interest in other fields cause the largest telescopes to overlook these stars. Thus, disregarded by independent and international astronomers alike, a plethora of these stars are waiting to be discovered and characterized. In this project, we intend to apply speckle interferometry, together with Fourier Analysis, to better resolve these stars. Although speckle interferometry has been used with interferometric binaries (0.2--0.3 arcsecond separation) with great success, we seek to apply this method to visual binaries in order to create a low-cost, standardized process that will be accessible to future research students$-$even those just entering astronomy research. Early results demonstrate that we can successfully resolve stars to within 4 arcseconds, with improvement achievable by using a red filter, greater magnification, and a shorter exposure time for our camera. We intend to implement these features to improve our camera's calibration and, separately, to expand the functionality of our binary catalogue data retrieval program. [Preview Abstract] |
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C01.00009: Long Slit Spectroscopy of the Nearby Galaxy NGC 300 Jarrod Johns, Jason Pinkney We present long slit spectroscopy of the nearby (1.9 Mpc) spiral galaxy NGC 300 from the Magellan I 6.5m Telescope. This galaxy is interesting because it is essentially bulgeless (type SA(s)d) but with a nuclear star cluster. We measured steller kinematics and gas kinematics along 4 PAs which cross the nuclear cluster. The spectral resolution is, unfortunately, not high enough to measure the small velocity dispersion accurately. The line of sight velocities suggest very little rotation in the stellar disk even along the major axis. They also show a velocity rise at the central star cluster suggesting a small motion relative to the disk. We measure gas kinematics from the weak [OIII] 500.7 nm line and see erratic velocities near the nucleus. [Preview Abstract] |
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C01.00010: New gas kinematics for the pseudobulge galaxy NGC 1291 Justin Chapman, Jason Pinkney We present new stellar and gas kinematics for the (R)SB(s)0/a galaxy NGC 1291 derived from long-slit spectroscopy taken with a Magellan 6.5-m telescope. Previously published stellar kinematics exist. This galaxy is of interest as it has an outer ring and both an outer bar and an inner bar. Also, it is a prototypical "pseudobulge". Pseudobulges differ from classical bulges in that they have supposedly formed out of gas inflow from the disk of the galaxy over an extended time period. Our gas kinematics are not what we would expect from this hypothesis. They show a very asymmetric rotation compared to the stellar component, i.e., the gas is decoupled from the stars. [Preview Abstract] |
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C01.00011: A search for galaxies with nuclear gas disks for observation by the JWST Alexander Lutheran, Jason Pinkney Studying the kinematics of the gas within galaxies allows one to determine the mass of the central supermassive black hole. High resolution images and long slit spectra are needed in order to start this process and the James Web Space Telescope (JWST) will play a crucial role in making the needed observations in the near future (2021 launch). The Near Infrared Spectrograph (NIRSpec) on the JWST has several suitable modes for gas kinematics. The most promising is the IFU (Integral Field Unit) with the G235H grating. We list emission lines that are produced by nuclear gas and also fall in the range of the best grating modes (G140H, G235H). Next we present a mosaic of optimal targets for the JWST. Starting with large surveys, we limited our results to early-type galaxies observed by the Hubble Space Telescope (HST) that have a detected nuclear dust disk, as dust disks imply the presence of a gas disk. We score and rank a refined list of over 30 galaxies, taking into consideration the dust morphology, distance, stellar velocity dispersion (used to calculate the black hole’s sphere of influence), detection of emission lines, and quality of existing data. [Preview Abstract] |
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C01.00012: Unmagnetized Rotating Yukawa Ring in a Dusty Plasma Matt Sibila, William Theisen A strongly coupled unmagnetized 1-D dust ring interacting through a Yukawa potential is created experimentally. Radial confinement is provided by a groove with a center pedestal. The dust particles rotate within the ring shaped potential well even though drag forces are present and there is no readily identifiable driving force. The rotation rate of the ring is measured and possible driving forces for rotation are examined. [Preview Abstract] |
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C01.00013: Improving the Forecasting of The Drivers of Severe Space Weather Megan Fisher, David Falconer, Ronald Moore, Sanjiv Tiwari The Sun produces large flares and coronal mass ejections (CMEs) that endanger astronauts. MAG4 is a large-database forecasting technique for forecasting an active regions (ARs) next day production rate of major flares from an ARs free energy proxy and short-term previous flare productivity. The free-energy proxy is measured from an HMI vector magnetogram. MAG4 presently uses a deprojected HMI vector magnetogram to estimate what the MDI AR line-of-sight magnetogram would look like, then applies the proxy measured from that to forecasting curves derived from MAG4s large database of MDI AR line-of-sight magnetograms and histories of major-flare production of 3,000 ARs. We quantify the improvements in MAG4s major-flare forecasting performance that result from using HMI forecasting curves instead of using MDI forecasting curves. We make a forecasting curve from the control sample and then use that curve to make a forecast for each AR magnetogram in the experimental sample. These forecasts are then compared to the observed major-flare productivity of the experimental-sample ARs and the Heidke skill score is calculated. From histogram of the differences in the Heidke scores, we find an increase in Heidke score of over 0.1 from using HMI forecasting curves, improving accuracy 10\%. [Preview Abstract] |
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C01.00014: Study of On-Si GeSn Gain Spectrum and Amplified Spontaneous Emission Zairui Li, James Gallagher, Imad Agha, José Menéndez, John Kouvetakis, Jay Mathews Molecules (from 2-20 $\mu $m) and atmospheric transmission (transmission windows of 3-5 $\mu $m and 8-13 $\mu $m) can experience strong characteristic vibrational transitions at mid-infrared spectral region. Which attract many researches on developing Mid Infrared lasers play an important role on spectroscopy, materials processing, chemical and biomolecular sensing, security and industry. The recent success in epitaxial growth of GeSn on-Si brings new development path on Mid Infrared. Si-based laser could also dramatically reduce costs for telecom components. High-performance computing will require advances in technology, and optical interconnects are one key component to increasing computing power. In this presentation, experimental results of amplified spontaneous emission of optical pumped GeSn waveguides within the IR range, will be presented to show a promising further of developing on-Si Mid Infrared laser. We will also show an experimental characterization of Ge and GeSn optical gain spectrum with pump probe system. This will help further understanding the material properties about optical emission of Ge and GeSn alloy leads to an enhancement and add progress on the development of on-Si GeSn Infrared laser. [Preview Abstract] |
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C01.00015: Enhancing a Solar Energy Teaching Lab David Erzen, Dennis Kuhl The purpose of this project was to improve a solar energy laboratory in an intro-level Energy Systems course taught at Marietta College. Current literature and physics faculty were consulted to develop enhancements allowing for further scientific inquiry. The lab handout was improved with the necessary information for students to contextualize the lab. The investigations included analyzing the power curve of a photovoltaic cell, the effect on power output due to temperature, and the effect on power output due to tilt angle. Improvements included the implementation of computer data logging allowing for larger, continuous data sets, and the construction of a measuring instrument that allowed students to adjust the tilt angle of a solar panel while keeping the axis of rotation constant. Generally, students with all different academic backgrounds appeared to be receptive to these modifications, synthesizing the content of the experiment for later practical use. [Preview Abstract] |
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C01.00016: Bridging biology, physics and research through high school -- university outreach Jeremy Rummer, Sam Speaks, Kaitlyn Flanigan, Nya Feinstein, Christopher Pierce, Eric Mumper, Brian Lower, Steven Lower, Ratnasingham Sooryakumar An outreach program for high school teachers and students and the Ohio State University has been created through support from the National Science Foundation. In this program, participants learn to use magnetic trapping devices to isolate and enrich magnetotactic bacteria (MTB) from environmental samples and study the underlying physics that describes these organisms and their propulsion. With input from associated faculty and graduate students from the Departments of Physics and Earth Sciences at Ohio State, the high school teachers develop interactive STEM curricula that use MTB as a platform for their own students. Teachers also learn to use their own magnetic traps and portable magnetic systems developed for this type of outreach. This portable unit runs on a standard electrical outlet (or a car battery) and uses a handheld Xbox controller for real time bacteria manipulation as well as projecting images of student - collected swimming MTB onto a screen. These activities use a fun, familiar device, like an Xbox controller to create connections between varying ``difficult'' concepts in biology (e.g. cellular structure, molecular genetics) and physics (e.g. magnetism, thermal motion, Archimedes' principle). An update on the activities and progress over the past year and a half will be presented. [Preview Abstract] |
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C01.00017: Optical Properties of Reactive Magnetron Sputtered Aluminum Nitride for use in Hyperbolic Metamaterials Rachel Adams, Said Elhamri, Hadley Smith, Madelyn Hill, Zachery Biegler, Kurt Eyink, Amber Reed Incorporating single photon emitters into practical applications is currently restricted by their low efficiency; this efficiency can be enhanced by coupling single photon emitters with plasmonic nanostructures. Hyperbolic metamaterials (HMMs) of metallic and dielectric nitrides are promising plasmonic nanostructures in the visible to near-IR range due to high temperature applications. Dielectric materials such as aluminum nitride (AlN) are of interest for creating HMMs when layered with a metallic material. In this work, the effects of growth parameters—nitrogen gas fraction, gas ion flux to metal neutral flux ratio, substrate temperature, and sputter power—on the microstructure, surface morphology, and optical properties of AlN are investigated. The AlN films in this study were deposited using reactive controllably unbalanced magnetron sputtering. X-ray diffraction was used to characterize the crystallinity and atomic force microscopy was used to determine the surface morphology of the films. The optical properties were determined by spectroscopic ellipsometry. [Preview Abstract] |
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C01.00018: Evaluating the effectiveness of a cleaning procedure of Au(111) surfaces using a residual gas analyzer Xuan Zhu, Craig Howald In order to perform atomic scale measurements on surfaces, for example with scanning tunneling and atomic force microscopes, it is important to have atomically clean surfaces. We investigate using a residual gas analyzer for determining the effectiveness of cleaning procedures. In particular, we used cycles of argon ion sputtering and annealing with a resistive heater to clean the surface of Au(111) samples. Differences in the measured partial pressures of different masses within the chamber during the sputtering and annealing procedures reveal changes in the sample cleanliness. [Preview Abstract] |
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C01.00019: Effect of Pd-based Nanoparticles on the Structural Properties of Electrospun Titania Nanofibers Daniel Isaacs, Nenad Stojilovic, Maja Scepanovic, Mirjana Grujic-Brojcin, Laila Shahreen, George Chase Electrospun titania nanofibers coated with PdO nanoparticles show promise for applications in catalyst support structures, for the reduction of NO and CO gases. The catalytic and optical properties of these flexible ceramic nanostructures can be tailored by controlling experimental conditions. In this project we investigate how Pd concentration within the electrospinning solution affects the anatase-to-rutile phase transition of the composite nanofibers. Structural properties are studied using X-rays diffraction (XRD) system and Raman spectroscopy whereas surface morphology was monitored using electron microscopy. [Preview Abstract] |
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C01.00020: Synthesis of Gallium Oxide Nanowires Kaleb Slaatthaug We have synthesized gallium oxide (GaO$_{\mathrm{2}})$ nanowires by depositing gallium onto a gold-covered silicon wafer at high temperatures. This is done by having a flow of N$_{\mathrm{2}}$ gas, kept above atmospheric pressure, pass through a tube furnace at 1000 C through an evaporated gallium sample, allowing the gallium to condense onto the wafer. When the system is held at low pressure, however, no synthesis occurs. [Preview Abstract] |
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C01.00021: ABSTRACT WITHDRAWN |
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C01.00022: Effect of match types on the fire propagation speeds in a match stick array Abigail Ambrose, Niklas Manz We investigated the slope effect on the propagation speed of fire fronts, using 3D-printed match stick array models with angles between $0^\circ$ and $45^\circ$, different conditions for the distance between neighboring match heads, and several match types of the same brand. We discovered different fire font propagation speeds for the planar, horizontal case with $\theta = 0^\circ$ for different match types (same dimensions but different chemical composition of the match head). These correlations also had an effect on the slope-speed relationship when testing the fire propagation in our three models: i) constant distance between the match heads along the horizontal axis ($x$-model), ii) constant distance between the match heads along the vertical axis ($z$-model), and iii) constant distance between the match heads along the slope ($r$-model). [Preview Abstract] |
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C01.00023: Optical sensor for normal force distribution Mengyue Sun The adhesion strategies in biological systems have been widely studied and have been a great source of bio-inspirations for human adhesive technologies. For practical applications of these adhesives at macro scales, it is crucial to understand the distribution of stresses at interface of adhesive system. we develop an optical sensor based on “frustrated total internal reflection (FTIR)” optics. In theory of FTIR, if an object is placed within tiny distance from the total internal reflected interface, some light will pass through the interface, so the camera can receive the signal. According to this method, we can measure tiny deformation from soft materials such as PDMS, and calculate the tensile stress based on deformation, thus this optical sensor is much more sensitive than the other biological sensors. Our sensor is composed of dove prism, 532nm laser beam light source, and several mirrors. The dove prism is used to achieve the FTIR at the interface between glass and PDMS thin film. According to calibration, our setup can measure distance in range of 0nm to 300nm accurately, and after applying pressure on the PDMS film, we did see signal but some improvements need to be made in future work. [Preview Abstract] |
(Author Not Attending)
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C01.00024: Study on the Process of Irregular Ocean Wave Generation Using Physical and Computational Analysis Hajin Kim, Henry H. Kang In the oceanography and ocean engineering study, various idealized spectra is used to obtain the wave properties such as wave amplitude and frequency. The actual ocean wave motion analysis is not so simple when the turbulence in the wind generate random fluctuations at the sea surface. More delicate and comprehensive numerical and computational studies are needed to perform the study of the marine waves. The wind creates small wavelets and these short waves continue to grow to become big waves. The waves finally deform their shape with low frequencies and low energy. In this study, two-parameter wave spectral formulation, dispersion relation and spectral density functions were used to find wave amplitude and to show the process of wave generation. Considering the wave equation with a random phase angle, this research focused on the prediction of the wind-generated irregular waves since the wave elevation in the random fluctuations presents a stochastic behavior. Various wind speeds as input data were tested to find relevant wave amplitudes. Wave amplitudes of fully developed wind-generated seas in the North Atlantic Ocean were obtained using linear theory, which employs superposition of a large number of monochromatic waves. [Preview Abstract] |
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C01.00025: Single-photon routing in many-emitter waveguide quantum electrodynamics Bibandhan Poudyal, Nathan kravitz, Ashwin Mishra, Imran Mirza Single-photon routing had seen a tremendous amount of research activity in the past decade due to its applicability in quantum information processing and on-chip quantum computing. The problem of single-photon routing in two single modes of waveguides coupled with a quantum emitter has already been studied [Phys. Rev. A 94, 063817 (2016)]. The focus of this study is to investigate how the presence of many emitters will influence the single-emitter version of photon routing scheme. The results of this work may find applications in quantum circuitry and many-body physics in optical systems. [Preview Abstract] |
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C01.00026: Dissipation effects to the disintegration of a multiply-charged quantum vortex Yucong Cai, Ikaika McKeague-McFadden, E. Carlo Samson Using 2D numerical simulations based on the Gross-Pitaevskii equation (GPE), we study the quantum vortices created by a blue-detuned optical beam that is dragged across a highly oblate Bose-Einstein condensate (BEC) in a spiral trajectory. The dependence of the generated vorticity to the beam’s optical power and to the trajectory parameters was analyzed. Dissipation was introduced to the simulations by adding a phenomenological damping term to the GPE. We explored how dissipation affects the vortex dynamics after ramping off the optical beam, wherein we observed spatial clustering of vortices, co-rotating vortices, and regular arrangement of vortices prior to break up. The break up dynamics of the giant vortex exhibited a transition from a symmetric configuration of single vortices to a disordered arrangement. The observed dissipation effects may help understand the role of thermal/background atoms to the onset of turbulence in BECs. [Preview Abstract] |
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C01.00027: Numerical Simulations of the Fast Adiabatic Transport of an Ultracold Quantum System Junjiang Li We study numerically the spatial transport of the ultracold atoms at very short time intervals without loss of fidelity. In many quantum technologies, one often needs to transport a quantum system through space rapidly while preserving fidelity. Among the many protocols designed to address this, shortcuts to adiabaticity (STA) is of special interest as it is incredibly robust against different kinds of quantum systems. However, its implementation requires an auxiliary potential be provided over a large region of space, which can be difficult to satisfy experimentally. One of the specific goals is to determine the relationship between the minimum transfer time and the minimum range of the auxiliary potential. To that end, we studied the behavior of Bose-Einstein condensates being transported by the STA protocol by numerically solving the Gross-Pitaevskii equation. Specifically, we are investigating the correlation between transport times and the necessary spatial extent of the auxiliary potential for a coherent transport. Preliminary results show an inverse correlation, which implies a limit on how fast a system can be transported when this protocol is implemented in experiments. We evaluate the performance of this fast transport protocol using experimentally feasible parameters. [Preview Abstract] |
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C01.00028: Quantifying Nitrogen-Vacancy Center Density in Diamond using Magnetic Resonance Morgan Hamilton, Carola Purser, Isaac Rampersaud, Arfaan Rampersaud, P. Chris Hammel Biologists have recently begun to use nanodiamonds as bright, florescent biomarkers. Florescence originates in transitions between the atomic-like, electronic energy levels of nitrogen-vacancy (NV) defects, composed of a nitrogen substitution adjacent to a carbon lattice vacancy. Engineering brighter nanodiamonds generally requires higher concentrations of NV centers, but quantifying these concentrations via optical measurements alone is prone to complications from surface termination, other defect concentrations, nanodiamond size, etc. Here, we aim to quantify NV densities from the intensity of their zero-field magnetic resonance absorption, centered at 2.87 GHz. To this end, we designed and characterized a tunable microwave cavity. For given cavity dimensions, Mathematica code was developed to visualize the resonant modes and calculate their resonant frequencies. From this a magnetic resonance cavity could be designed, and it was demonstrated that the measured resonance frequency matches the theoretical value very well as a function of the cavity length. Coupling from a coaxial microwave line to the cavity was enabled using a loop antenna. By modifying the inductance of the loop, the quality factor of the cavity was enhanced by a factor of three. We thus demonstrated a tunable microwave cavity that can be made to resonate with NV spins. Future work will involve incorporating the cavity in a magnet to measure the microwave absorption amplitude. [Preview Abstract] |
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C01.00029: Controllable negative differential resistance on charge transport through DNA molecules Yong Joe A double-stranded DNA molecule subject to a perpendicular gating electric field and a small mechanical strain exhibits a negative differential resistance (NDR) in its current-voltage (I-V) characteristics. Using an advanced two-dimensional tight-binding model including hopping integrals for the next nearest-neighbors, we implement perturbative strain- and tilted angle-dependent DNA helix conformation in conjunction with the theories of Slater-Koster and linear elasticity. The degree of NDR can be tuned by adjusting the tilt angle and mechanical strain of the DNA. This effect arises because of a surface charge distribution near the contacts due to the normal component of the electric field and structural change of the DNA molecule due to the strain. It is shown that enhancement of NDR peak current and a large peak-to-valley ratio of NDR are achieved by an increase of the tilt angle and stretching strain. Finally, a series of step-like current jumps without NDR features are exhibited in the weak DNA-lead coupling regime. This disappearance of NDR stems from the fact that reduced conduction through metal electrodes with a sufficiently small tunneling rate compensates the current drop. [Preview Abstract] |
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C01.00030: Structure and dynamics of a Ag-doped chalcogenide glass: an \textbf{\textit{ab initio}} study Dale Igram, Horacio Castillo, David Drabold The vibrational properties of a ternary glassy chalcogenide material, Ag$_{\mathrm{20}}$Ge$_{\mathrm{28}}$Se$_{\mathrm{52}}$, are analyzed. The vibrational density of states and atomic participation ratios calculations revealed that Se atoms are a major contributor across the vibrational spectrum. The abrupt change and plateau of the stretching character may be due to vibrational contribution changes and a difference in the rate of change for the Ge and Se atoms, respectively. The divergence of the perpendicular phase quotient is due to the rocking motion of a Ge-Ge compound. A1 breathing modes of the corner-sharing tetrahedra showed that these breathing modes are non-local and involve the mixing of modes of different symmetry resulting in two bands of A1 breathing modes. [Preview Abstract] |
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C01.00031: The key ingredient in order finding: quantum Fourier transform through examples Bradley Lockhart, Mellita Caragiu This work is the outcome of our consulting several quantum computing books and articles in an attempt to find works that achieve a balance between technical detail and expository quality. It is part of our effort of putting together an introduction to particular core ideas of quantum computing theory that is also accessible to undergraduates. The main theme considered here is the quantum Fourier transform as an essential ingredient in obtaining the period of a sequence of natural numbers (otherwise known as order finding). The issue arises in Shor's algorithm of factoring large numbers, a task that it is believed that quantum computers would perform with a much higher efficiency than classical ones. [Preview Abstract] |
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C01.00032: Discrete Tree Based Fire Simulation Joseph Theiss, Niklas Manz Using a cell-based model with a quasi-physical simulation, we simulated the mechanics of heat transfer and buoyancy to observe a fire's geometry and calibrate it to measured values for further testing. We then simulated the results of a fire spread through 4 to 6 trees of constant separation placed on varying slopes to observe the effects of slope on fire propagation. We find that simple fire spread can be characterized by three factors: tree height, tree separation, and slope. Tree height was measured over 5 variations, tree separation was measured over 9, and slope was measured over the range of –90 to 90 degrees in 5 degree increments. Tree separation and tree height both showed to be dependent on regular functions: exponential and linear respectfully. Slope was determined to be a multi-part piecewise function. Further, fire front velocity was highly dependent on the ability and rate of fire to propagate downward on trees, up until a critical angle based on flame geometry. [Preview Abstract] |
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C01.00033: Disruption and Recovery of Reaction-Diffusion Wavefronts Colliding with Obstacles Niklas Manz, Rebecca Glaser, Nathaniel J. Smith, Vincent W.H. Hui, John F. Lindner We study the damage to and restoration of planar reaction-diffusion wavefronts colliding with convex obstacles in narrow two-dimensional channels using finite-difference numerical integration of the Tyson-Fife reduction of the Oregonator model of the Belousov-Zhabotinsky reaction. We characterize the obstacles' effects on the wavefront shape by plotting wavefront delay versus time. Due to the curvature dependent wavefront velocities, the initial planar wavefront (or iso-concentration line) is restored after a relaxation period that can be characterized by a power-law. We find that recovery times are insensitive to obstacle concatenation or to the upstream obstacle shape but are sensitive to the downstream shape, with a vertical back side causing the longest disruption. Delays vary cyclically with obstacle orientations. The relaxation power-laws confirm that larger obstacles produce larger wavefront delays and longer recovery times, and for a given area larger obstacle width-to-length ratios produce longer delays. Possible applications include elucidating the effect of inhomogeneities on wavefront recovery in cardiac tissue. [Preview Abstract] |
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C01.00034: An overview of discrete dipole approximation by means of Graphics Processing Unit, Fast Fourier Transform, and Complex Conjugate Gradient in MATLAB Masoud Shabaninezhad Navrood, Muaaz Gul Awan, Guda Ramakrishna In this work, we review discrete dipole approximation (DDA) as a numerical method to calculate the optical properties of arbitrary shaped metallic nanoparticles (NPs). In this method, the target particle will be divided into N-cubes which each one representing a point dipole with polarizability of $\alpha_{\mathrm{i}}$ that interacts with the electric field of the incident light and N-1 other dipoles. We discuss polarizability function, induced dipoles and dipole interaction matrix, and consequently we explained how to calculate absorption, scattering, and extinction efficiencies, field enhancement around single nanoparticle and hot spot in the dimer structures. To calculate dipole moments, Fast Fourier Transform (FFT) and Biconjugate Gradient (BCG) along with their corresponding numerical aspects have been reviewed to accelerate the computation time and to reduce the required memory. In the end, we applied a graphic processing unit (GPU) algorithm to reduce the time and required computational memory. By applying GPU, the simulation significantly reduced in compare to CPU. It is worth mentioning that all of the codes is developed by our group in MATLAB software. [Preview Abstract] |
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C01.00035: Characterization of Ultraviolet ZnO Photodetector Sage Edwards, Tom Oder An ultraviolet photodetector was fabricated based on zinc oxide semiconductor films. A pair of ohmic contact metals, comprising of Ti and Au was deposited by magnetron sputter deposition followed by annealing at 200 $^{\mathrm{o}}$C in oxygen for 60 seconds. The gap between the two ohmic contact strips was 0.8 mm. Characterization of the sensor's photoresponsivity was implemented by focusing an incident broadband beam of light from a lamp into a monochromator. The light from the monochromator was then focused to the sample which formed part of a balanced Whetstone bridge circuit. The photodetector was found to have a steep responsivity from around 380 nm, which is in the UV range. Significant persistent photoconductivity was also observed during photoresponsivity measurements. [Preview Abstract] |
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C01.00036: Avalanche Dynamics and Angle of Repose of a Cohesive, Conical Bead Pile David Morrow, Susan Lehman Slip avalanches on a slowly driven pile are investigated experimentally using a 3D conical pile built from uniform 3~mm steel beads. Beads are added to the pile by dropping them onto the apex one at a time; avalanche size is measured through changes in pile mass. To better understand the dynamic motion of individual avalanches, we investigated the changes in the angle of repose of the bead pile. By adding a uniform magnetic field from a set of Helmholtz coils, we are able to control the cohesion between the beads. Measurements of the change in angle of repose caused by large avalanches were taken at three different cohesion levels. The change in angle of repose was studied as a function of both the size of the avalanche as well as the cohesion of the pile. We find that increased cohesion tends to also increase the change in the angle of repose, even comparing avalanches of the same size. To further understand the avalanche dynamics, we use video analysis of the surface of the pile to characterize the surface activity of the pile. The relationship between the surface activity of an avalanche and the change in the angle of repose is under investigation. [Preview Abstract] |
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C01.00037: Effect of Electron-electron Scattering on Linear Conductivity for Graphene-like Band Structure Ben Yu-Kuang Hu, Fereshteh Memarian We study theoretically the effect of electron-electron scattering on the electrical conductivity of two-dimensional materials with linear bands such as graphene, both with and without a perpendicular magnetic field. The Boltzmann transport equation was utilized, where phonon and impurity scattering are modeled using the relaxation-time approximation. In graphene-like materials with linear bands, for a constant relaxation time, the conductivity decreases as the temperature increases from absolute zero. Furthermore, in linear band materials, the electron-electron scattering also decreases the conductivity. This is in contrast to parabolic band materials, where the conductivity for a constant relaxation time does not depend on temperature or the electron-electron scattering rate. We also investigate the magneto-conductance for linear band materials in the absence and presence of electron-electron scattering. [Preview Abstract] |
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C01.00038: Modeling the Thermal Conductivity of Hybrid Perovskites Matthew S. Slodov, Jeffrey S. Dyck, Robert Stanek, Anton Kovalsky, Clemens Burda Hybrid perovskites are crystals with a specific structure made up of both organic and inorganic components. These crystals have shown potential to make more efficient solar cells, but their physical properties are not well understood. The properties of these crystals were studied through modeling their thermal conductivity as a function of temperature. The Debye model for thermal conductivity was used as a basis for the modeling. Specifically, the perovskites Methylammonium Lead Iodide, Bromide, and Chloride (MAPbX$_{\mathrm{3}}$, X $=$ I, Br, Cl) and their physical properties of point defects, Umklapp phonon scattering, and grain boundary size were studied. From the samples provided, MAPbI$_{\mathrm{3}}$ had the most point defects, and MAPbBr3 had the greatest Umklapp scattering. More research is required to better understand these perovskites and implement them in technology. We gratefully acknowledge John Carroll University in supporting this research. [Preview Abstract] |
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C01.00039: Characterization and Photoconductivity Measurements of Methylammonium Lead Iodide Perovskite Thin Films David R. Sprenger, Jeffrey S. Dyck, Robert Stanek, Clemens Burda Methylammonium lead iodide is a material with highly desirable photoconductive properties, making it very efficient for use in solar panels. Thin films of methylammonium lead iodide were prepared by spin-coating solutions of lead(II) iodide and methylammonium iodide onto a glass slide, followed by annealing on a hot plate in inert atmosphere. X-ray diffraction and electron microscope data showed the films were of moderate quality. The photoconductive properties in vacuum of the films were characterized under illumination by white light, in addition to narrow-spectrum red and blue light from high power light emitting diodes. The current-voltage characteristics were verified to be Ohmic. The electrical resistance versus light intensity and wavelength trends were compared to various models of photoconduction. We gratefully acknowledge support from John Carroll University and the Ferro Corporation. [Preview Abstract] |
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