Bulletin of the American Physical Society
20th Annual Meeting of the APS Northwest Section
Volume 64, Number 9
Thursday–Saturday, May 16–18, 2019; Western Washington University, Bellingham, Washington
Session E1: Poster Session I |
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Room: SMATE Lobby |
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E1.00001: Visualization and Modeling of Transcriptional Bursting By Live Cell Imaging Abigail Figueroa, Bryson Gray, John Martin, Michael Pool, Matthew Ferguson Recent high-resolution contact mapping has made it possible to see the 3D organization of the nucleus on an unprecedented length scale (at 1kb resolution)[1,2]. Since the average human gene is 12kb, this information is finally below a critical limit, and we are now in a position to understand the principles underlying epigenetic programming. One of the challenges of understanding the regulation of gene expression is developing tools and protocols that capture the complex spatiotemporal dynamics of these functions without compromising sampling rates, timescales, visibility of the sample, and all within a single living cell. The goal of our project is to develop a protocol for using 3D orbital tracking microscopy and in vivo RNA labeling to provide measurements of the cooperative binding of transcription factors and reprogramming of the human genome at a single active transcription site within a living cell. Using coarse grained modeling, GPU acceleration and Hi-C data, we intend to develop a dynamic model of the human genome to test an enhancer promoter looping model for transcriptional bursting and epigenetic regulation. [Preview Abstract] |
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E1.00002: A Minimal Model for Conical Splash Cups Using Conformal Mapping Aidan Schumann While most flowers use animals or wind to distribute seeds, splash-cup plants accelerate rain drops to ballistically fling their seeds through the air. Most splash cups have a conical shape---much like a cocktail glass---which, upon being hit by a rain drop, channels the water to send it out the other side at increased speeds. We present a minimal model to understand the effects of the conical geometry on the acceleration of the rain drop. We employ an Euler fluid with a conformal mapping to find the velocity field within the conical geometry. Our results imply that the primary effect of a steeper cup angle---outside of changing the launch angle---is to make the impact site effectively closer to the center of the cup. [Preview Abstract] |
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E1.00003: Predicting non-functional mutations in protein complexes Casey Beard, Jagdish Patel, James VanLeuvan, LuAnn Scott, Miller Craig, Holly Wichman, F. Marty Ytreberg Robust methods to predict the effects of mutation upon protein free energy have many important applications in understanding the consequences of real-time viral evolution. In our research, we seek to develop an effective computational approach for narrowing down the list of viable mutations. We have chosen the bacteriophage $\varphi $X174 as a model to develop this computational approach. Specifically, we focused on mutations within the spike protein, G, located on the viral capsid. Using snapshots generated via molecular dynamics simulations, we predicted the biophysical effects of all possible single mutations within the G protein using FoldX. FoldX has a semi-empirical scoring function that requires a minimum of computational resources, allowing calculation of all possible stability changes to binding and folding among the G pentamer, as well as the binding between protein G and the viral capsid protein, F. We then compared these calculated values to empirically-derived results for a subset of the mutations to protein G. Statistical analysis revealed a relationship between simulated free energy changes and the experimentally-determined viability of the mutation, allowing us to separate viable from nonviable mutants. [Preview Abstract] |
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E1.00004: Thermo-chemical Stability Analysis of Phytoncide Components Using Computational and Biochemical Simulations Hyunjin Chang, Isabella Baek, Richard Kyung Sophoraflavanone molecule is a volatile phytoncide that can be released into the atmosphere. Scientific efforts have focused on finding either naturally-made compounds that can be used as potential for treatment of chronic inflammatory disorders such as rheumatoid arthritis. Also it has been found to enhance the effect of currently used antibiotics by affecting the growth of antibiotic-resistant bacteria. Due to an its antibiotic-resistant bacteria, scientific efforts have focused on finding either naturally-made or genetically modified compounds that can treat and or prevent these harmful and sometimes deadly bacteria. Sophoraflavanone G, due to its use as a phytoncide, has been found to impact the growth of antibiotic-resistant bacteria and enhance the effect of currently used antibiotics. Since the antimicrobial potency and range of phytoncides vary greatly among species, bioactivity of antioxidant components of extracts from Sophora flavescens was studied. In this paper, the antioxidant activity of S. flavescens with different origins was evaluated by a computational chemical software which measures the optimized geometries and chemical properties of the modeled structures by using theoretical values and considering the molecules’ atomic properties. [Preview Abstract] |
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E1.00005: Angular Momentum in Fluids Robert Close Classical mechanics features three prominent independent conserved quantities: energy, momentum, and angular momentum. However, only the first two of these conservation laws are routinely applied to analysis of fluid motion. Conservation of angular momentum is neglected because no local representation of the conservation law has been available (${\rm {\bf r}}\times {\rm {\bf p}}$ is non-local). However, it has recently been shown that spin density, the field whose curl is equal to twice the momentum density, provides a local representation of angular momentum density. Spin density is uniquely defined as twice the vector potential resulting from Helmholtz decomposition of momentum density. Previous analysis of spin density in an ideal elastic solid yields the Dirac equation and all of the dynamical operators of relativistic quantum mechanics, including spin and orbital angular momentum. When applied to fluid dynamics, the spin density equation provides an independent constraint on the motion in addition to the Navier-Stokes momentum density equation. The equation of evolution of spin density completely determines incompressible motion, thereby simplifying calculation of the evolution of fluid motion from initial conditions. [Preview Abstract] |
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E1.00006: Multi-Grand, Multi-Canonical, Flat Histogram, Monte Carlo Simulations for the Square Well Fluid. Cade Trotter Currently micro-canonical at histogram simulations are used to give properties of the micro-canonical ensemble at all temperatures of a system with a constant number has recently developed a grand-canonical at histogram capable of giving thermodynamic properties at any number of atoms in a system with a given temperature. While both micro-canonical and grand-canonical work very well, we have combined the two methods to create a multi-grand, multi-canonical at histogram, Monte Carlo simulation. Our newly proposed method functions by allowing for a simulation to change in energy, and number of atoms at any temperature. By allowing for so many degrees of freedom we are able to produce the entire equation of state from just one simulation. [Preview Abstract] |
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E1.00007: Ground state phases of a quasi-2D BEC of rigid rotor molecules via Bogoliubov mean-field theory Nathaniel Chapman, Seth Rittenhouse, Brandon Peden We investigate the quadrupolar properties of the ground state and low-energy excitations of a Bose-Einstein condensate of rigid rotor molecules confined harmonically in two dimensions. A gradient field is applied that induces molecular quadrupole moments, and the molecules interact via quadrupole-quadrupole interactions. Via a Bogoliubov mean-field analysis, we identify a second-order phase transition between liquid-crystal-like uniaxial and biaxial nematic phases driven by the strength of the quadrupolar interactions and associated with the spontaneous symmetry-breaking of azimuthal symmetry in the plane. We investigate the stability of these phases by way of the dispersion relations of the low-energy excitations. [Preview Abstract] |
(Author Not Attending)
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E1.00008: Phase diagram and quantum oscillations of RAgSb2 R$=$(La, Gd) Anna Roche, Shua Sanchez, Jiun-Haw Chu Previous research suggests an association between~high-temperature~superconductivity and a quantum critical point arising from suppression of the magnetic and/or structural phase transitions~via chemical doping. Here, we explore a chemical doping sequence of~LaAgSb$_{\mathrm{2}}$ and GdAgSb$_{\mathrm{2}}$~to study a similar phase competition found in many~copper-based and~iron-based~high-temperature superconductors. Systematic measurements of the resistivity, susceptibility, and quantum oscillations are presented~for single-crystal samples of the~chemically substituted~RAgSb$_{\mathrm{2}}$~(R$=$Gd,La). Doping the parent compound LaAgSb$_{\mathrm{2}}$~with Gd explores the effect of~magnetic doping and~applying chemical pressure to~the crystal. La$_{\mathrm{1-x}}$Gd$_{\mathrm{x}}$AgSb$_{\mathrm{2~}}$exhibits charge density ordering around that is suppressed with increase Gd percentages, while Gd$_{\mathrm{1-x}}$Y$_{\mathrm{x}}$AgSb$_{\mathrm{2}}$~exhibits anti-ferromagnetic ordering that is suppressed with increasing Y percentages. Resistivity and susceptibility data are used to identify phase transition temperatures and create a temperature vs doping phase diagram for each chemical substitution family. These diagrams show a strong suppression of charge density waves with magnetic gadolinium doping and the appearance of an antiferromagnetic state, with no apparent coexistence of charge and magnetic ordering. Additionally, magnetic quantum oscillation data are presented showing the changes in the Fermi surface and effective mass with chemical doping. [Preview Abstract] |
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E1.00009: Adsorption Energies for Ten van der Waals Gases on a Zr-based Metal-Organic-Framework (MOF) Oscar Vilches, Graeme Vissers, Wei Zhang, Charles Campbell MOFs are relatively novel crystalline, high controlled porosity, very large adsorption specific area materials designed for use as catalyst support and applications to scientific and applied problems. We present measurements of adsorption isotherms of ten gases (H$_{\mathrm{2}}$, D$_{\mathrm{2}}$, Ne, N$_{\mathrm{2}}$, Ar, CO, CH$_{\mathrm{4}}$, Kr, Xe and C$_{\mathrm{2}}$H$_{\mathrm{6}})$ over a wide range of the appropriate temperatures on a Zr-based MOF$_{\mathrm{\thinspace }}$known as NU-1000 of specific area $\approx $2600 m$^{\mathrm{2}}$/gram. A first set of measurements$^{\mathrm{1}}$ was used to calculate the differential heat of adsorption over the entire monolayer range. A second set emphasized the four central atoms/molecules in the series (N$_{\mathrm{2}}$, CO, Ar and CH$_{\mathrm{4}})$ for coverages under 0.1 monolayer for which density functional calculations (DFT) of the enthalpy of adsorption at zero coverage showed considerable variations. The DFT results indicated several strong adsorption sites with energy differences amongst them large enough for experimental observation. Our results show remarkable qualitative and semi-quantitative agreement with the DFT calculations assuming a sequential filling of sites, from strongest to weaker energies.$^{\mathrm{2}}$ 1. W. Zhang et al., J. Am. Chem. Soc., 140, 328 (2018) 2. G. O. Vissers et al., J. Phys. Chem. C, (2019), in press. [Preview Abstract] |
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E1.00010: Bottom-Up Shape Engineering of Molecular Single-Crystals. Griffin Reed, Matthew Littleton, Haley Doran, David Patrick The ability to fabricate complex submicron-scale components from inorganic crystalline semiconductor materials such as c-Si enables countless modern technologies, from microelectromechanical systems to integrated circuits. For single-crystal molecular materials on the other hand, comparable approaches to defining micron- and submicron-scale structure are much less well developed, in part because weak intermolecular binding forces make molecular crystals vulnerable to damage by conventional techniques such as photolithography and energetic beam milling. Here we show how the same weak forces that are problematic for top-down patterning of molecular crystals can be exploited to enable controlled bottom-up growth, by leveraging shape plasticity. We describe a new approach to molecular single-crystal engineering based on bottom-up growth of single-crystals on sacrificial templates by vapor-liquid-solid (VLS) deposition. We demonstrate how these templates serve as molds for crystal formation, enabling growth of single-crystals with complex, even extraordinary shapes. The resulting new class of materials may help unlock functional features for molecular single-crystals via microstructural control over their photonic, thermal, charge transport, mechanical, and other fundamentally interesting and technologically valuable properties. Results are presented demonstrating a wide range of shape- and size-control modalities, including crystal topology, bounding perimeter shape, and nucleation position, for several families of small-molecule organic semiconductor and pharmaceutical compounds. [Preview Abstract] |
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E1.00011: Improved Dispersion of CuInS$_{\mathrm{\mathbf{2}}}$\textbf{/ZnS Quantum Dots in Poly(methylmethacrylate) for High Performance Luminescent Solar Concentrators}. Justin Doyle, Daniel Korus, Maya Noesen, Meredith Boxx, Kayla Koch, Yongjun Chen, Megan Plummer, David Rider, Stephen McDowall, David Patrick Luminescent solar concentrators (LSCs) use down-converting luminophores embedded in a waveguide to absorb sunlight and deliver high irradiance, narrowband output light for driving photovoltaic (PV) and other solar energy conversion devices. Achieving a technologically useful level of optical gain requires bright, broadly absorbing, large-Stokes-shift luminophores incorporated into low-loss waveguides, a combination that has long posed a challenge to the development of practical LSCs. With the recent introduction of a new generation of broadband, high-brightness, giant effective Stokes Shift phosphors based on materials such as CuInS$_{\mathrm{2}}$ and Mn:ZnSe nanocrystals (NCs), LSCs have come closer to commercial viability. However a key remaining challenge concerns incorporation of NCs into technologically-relevant waveguide materials, especially poly(methylmethacrylate), where aggregation occurs at even very low loadings, leading to unacceptable light-scattering losses. This poster describes a strategy for achieving uniform dispersion at even high NC loading, by substituting native NC ligands for diblock poly(styrene)-poly(methylmethacrylate) oligomeric ligands. Using this strategy we describe CuInS$_{\mathrm{2}}$/ZnS-based LSCs demonstrating outstanding performance as large-area, semitransparent concentrators suitable for use in energy-harvesting window layers and related applications. [Preview Abstract] |
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E1.00012: Formation enthalpy of a four-defect in GdAl$_{\mathrm{2}}$ Windy Olsen, Gary S Collins GdAl$_{\mathrm{2}}$ has the cubic Laves crystal structure. Indium solute atoms were previously observed to occupy both Gd- and Al-sites with site-fractions that varied in response to changes in composition or temperature [1]. Five Al-rich samples exhibited a transfer enthalpy for In of 0.343(7) eV between the two sublattices [1]. It was assumed in that study that the deviation from stoichiometry was sufficiently great that all point defects were structural and their mole fractions were independent of temperature. New analyses for other samples having compositions much closer to stoichiometry appear to show an equilibrium transfer enthalpy that is much smaller, close to 0.00 eV. The difference in enthalpies was shown in [1] to equal one-fourth of the activation enthalpy to form a thermally-activated combination of four elementary defects: 3 Al-vacancies and one Al-antisite atom on the Gd-sublattice. One can therefore infer a formation enthalpy of 4 x 0.34 eV$=$ 1.36 eV for the four-defect combination. [1] Matthew O. Zacate and Gary S. Collins, Phys. Rev. B69, 174202 (2004). [Preview Abstract] |
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E1.00013: Source self-absorption in PAC experiments Bryant Ward, Annesh Mukhopadhyay, Gary S Collins PAC experiments were carried out previously to measure the ratio of site-fractions of In solute atoms on Gd- and Al-sublattice in the intermetallic compound GdAl2 [1]. PAC is a spectroscopy measuring the time and angular correlation of two gamma-rays emitted successively in a nuclear decay. Spectra measured at relative angles of 180- and 90-degrees are then algebraically combined to determine a perturbation function that contains signals for solutes on both of the sublattices. However, for source samples having masses of 100 mg or greater, there is methodological disturbance to the perturbation function that mimics a signal for solutes on the Gd-sublattice. This is because coincidence counts measured at counter angles of 180-degrees are preferentially absorbed relative to 90-degrees. In order to obtain accurate values of site-fraction ratios, calculations are in progress to correct for this disturbance and will be reported at the meeting. [1] Matthew O. Zacate and Gary S. Collins, Phys. Rev. B69, 174202 (2004). [Preview Abstract] |
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E1.00014: Investigation of Surface Plasmon Resonance Biosensor Sensitivity Using Kretschmann ATR Theory MacKenzie Jewell, Sarah Clark, Valerie Beale, Karissa Langevin, Brad Johnson, Janelle Leger Surface plasmon resonance (SPR) is a phenomenon wherein an incident photon couples to charge density oscillations on a metal surface, exciting a surface plasmon polariton (SPP). SPPs are interface-confined modes that propagate along metal-dielectric waveguide structures. Attenuated total reflection (ATR) is the method by which a coupling prism is used to excite SPPs. Using ATR, a SPR biosensor monitors binding interactions at a metal surface in real time, as binding results in a shift in SPP excitation conditions. SPR biosensor performance is limited by the sensitivity of detection. Recent evidence suggests that sensitivity can be increased for SPPs with high propagation lengths. SPR biosensors require the Kretschmann ATR configuration, in which the metal film is exposed for monitoring. While Kretschmann ATR is often used experimentally, complete theoretical models for this configuration are lacking. In order to understand the relationship between SPP propagation and biosensor sensitivity, the complete electromagnetic theory must be developed. Here we discuss development of this theory and the correlation to experimental measurements. Our results show a positive correlation between SPP propagation lengths and biosensor sensitivity. [Preview Abstract] |
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E1.00015: Quasi-One-Dimensional Magnetism in Transition-Metal Antimony and Tantalum Oxides John J. Neumeier, Aaron B. Christian We have investigated the magnetic properties of transition metal oxides with the chemical formulae $A$Sb$_2$O$_6$ and $A$Ta$_2$O$_6$, where $A$ is a transition metal. The samples are single crystals that are grown using vapor transport or an optical-image furnace. They form layered structures with $A$-O-O-$A$ chains. The chains lie in the $a$-$b$ planes of the tetragonal structure. Neighboring chains along the $c$ axis alternate their orientation by 90$^\circ$. This unusual arrangement leads to poor magnetic coupling between the chains, and quasi-one-dimensional antiferromagnetism. The magnetic ordering is easily destroyed if the magnetic field applied perpendicular to the chains. Since this can only be achieved at most for half of the chains if the field is in the $a$-$b$ plane, two magnetic ordering temperatures can be observed. One outcome of this is an extremely unusual magnetocaloric effect. If rotated in constant magnetic field, the samples warm and cool. This presentation will discuss the crystal growth, measurements, the thermodynamics of the magnetocaloric effect, and unusual aspects of the physics of low-dimensional systems. [Preview Abstract] |
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E1.00016: Scalability and Function of Lithium Thionyl Chloride Batteries for Encoders in High-Degree-of-Freedom Robotic Systems Richard Stevens, Rene Maura, Eric Wolbrecht, Joel Perry Encoders are used to indicate the location of each component in robotic systems. Long-life, low-current batteries are used to provide power to encoders when motor drivers are powered down. In medical devices, correct encoder readout is critical to patient safety. Lithium Thionyl Chloride batteries are a common choice for maintaining encoder location integrity. This type of battery has a long shelf life and stable output voltage. Our specific application is a Bilateral Upper-extremity Exoskeleton for Simultaneous Assessment of Biomechanical and Neuromuscular Output (BLUE SABINO) that will measure bilateral aspects of motor intention and motor performance in the human arm. The system will have 30 degrees-of-freedom, 18 of which are controlled by Harmonic Drive motors using 17-bit encoders. The expectation of Harmonic Drive is to have an independent battery for each encoder. Our hypothesis is that, for large systems, a single battery might be used to power 10 or more encoders, reducing cost and maintenance, while maintaining the safety of the system. V-I curves for several different sizes and brands of batteries will be presented, along with projected lifetimes in example applications and specific current requirements by the encoder. [Preview Abstract] |
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E1.00017: Conductivity and Stability Analysis of Dielectrics Using Computational and Physical Calculations Jaemin Choung, Duong Dai Dinh, Richard Kyung Many of the researches around the world had been consistently looking for new energy source, but not as much as on the efficient storage of energy produced from these eco-friendly sources. This research considers how to increase the capacitance though inserting dielectrics to use it as a substantial tool for sustainable development. Also the Metal Organic Frameworks (MOFs), composed of inorganic metal joints and organic carbon linkers, are considered for the study since the MOFs are porous and have large spaces within them that can store charges for alternative energy sources. This research focuses on increasing capacity of batteries using different materials as dielectrics, differing the structure of capacitors, and various combinations of inorganic metal joints and organic carbon links in order to increase the maximum capacity of batteries that can store more energy with better efficiency. Computational physics, modeling and electron properties have been employed to figure out the stability and conductivity of the materials. Computer programming was used to optimize the movement of potential charges within capacitors in order to measure the maximum capacitance possible between capacitors and their change in geometry. [Preview Abstract] |
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E1.00018: Dynamic Relativity: How Extra Gravity Halos are Projected from Galactic Cores John Huenefeld Adding an inward dynamic to General Relativity provides the basis for ongoing space-time contraction within a gravitational field. Unlike Hubble expansion, this contraction field is non linear with distance and is dependent on the amount of concentrated matter generating the field. Rather than assuming additional mass to boost the orbital velocity of stars around a galactic core, this field acts to boost the acceleration of Newtonian gravity to achieve rotation curves consistent with observation. Using only the normal matter within the galaxy, it can be shown how Extra Gravity Halos (EGH), are generated by galactic nuclei. As the search for dark matter particles continues to bear no fruit, it becomes ever more important to consider alternatives. The gravity scale factor, which falls easily from the math, has just the right shape with radius to replicate the effects of assumed dark matter distributions. Not only do these contraction fields explain galaxy rotation curves, they also explain the Bullet Cluster, and Ultra Diffuse galaxies composed of either nearly all or nearly no dark matter. [Preview Abstract] |
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E1.00019: Improving Visualization Techniques for Nanohertz Gravitational Wave Searches Kyle Gersbach, Jeffrey Hazboun The complexity of modern computational modeling and simulation techniques in all areas of astrophysics has skyrocketed in recent years. The Bayesian modeling techniques used for gravitational-wave analyses by the North American Nanohertz Observatory for Gravitational waves (NANOGrav) incorporate 14+ years of pulsar timing data from over 70 pulsars. They use Markov Chain Monte Carlo (MCMC) sampling to numerically calculate likelihoods consisting of hundreds of parameters, often taking weeks to run a full analysis. \newline \newline In conjunction with the output of the NANOGrav data analysis suite, we visualize the in-progress MCMC sampling using an interactive plotting package in Python called Bokeh. Through this easy-to-use interface this software allows for real-time debugging and monitoring of Bayesian analysis, giving the user a chance to catch mistakes early on in weeks-long computations. This visualization especially benefits those with limited experience with the MCMC process. [Preview Abstract] |
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E1.00020: Data Quality Studies for the Laser Interferometer Gravitational-wave Observatory (LIGO) Sukhjit Kaur Massive objects in space such as black holes and neutron stars interacting with each other result in gravitational waves. Gravitational waves are curvature in the fabric of space-time and carry important information about their source. Though Albert Einstein first theorized the existence of gravitational waves, it was not until September 2015 that the first gravitational wave detection was made by the Laser Interferometer Gravitational-wave Observatory (LIGO). Since the first detection, many more successful detections have been made providing brand new insight to the universe. The LIGO interferometers are highly sensitive and can be disturbed by unwanted interference resulting in possibly contaminated data. Short duration transient noise events are known as glitches and are limiting to the sensitivity of the LIGO searches for gravitational-wave signals.~One of many ways LIGO scientists remedy this problem is using a citizen-science project called `Gravity Spy' launched on the `Zooniverse' platform. This project uses the participation of the general public to classify glitches in order to find the source of the glitch and thus rid the experiment of the noise. This all results in a cleaner data set that allows LIGO scientists to make confident and successful detections. [Preview Abstract] |
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E1.00021: Physics of Dark Energy Charles Sven Everything that we know about our Universe is the product of someone's mind, putting together their thoughts about observations into a creation that becomes the best explanation of that set of observed phenomenon that becomes one of the laws of physics. We have had our observational senses enhanced by the invention of microscopes, telescopes and everything in between allowing us to seek answers to deepest questions of the day including what is the Physics of Dark Energy? In that the current cosmological concept of our Universe's atoms were created from a `singleton' popping out of `nothing' is unsupported by physics and is not well received, that indicates that we need to study these atoms for a better explanation. In that light, here is assembled a number of pertinent facts when properly arranged, allows us to understand the physics of dark energy -- before, during, and after the Big Bang. . [Preview Abstract] |
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E1.00022: Instantaneous and Cumulative Star Formation in Moderate Redshift Galaxy Clusters Jacob Curtis, Kenneth Rines, Rose Finn, Alexey Vikhlinin Galaxy clusters provide a laboratory for determining the impact of environment on star formation in galaxies. Spitzer IRAC and MIPS photometry is used to measure stellar masses and star formation rates in a sample of 36 X-ray-selected clusters at moderate redshift. Statistical background subtraction is applied to IRAC photometry to construct luminosity functions. Using MIPS 24-micron imaging, mid-infrared sources are identified as candidate star-forming galaxies. Likely cluster members and instantaneous star formation rate are determined by IRAC and optical photometry. Specific star formation rates for the cluster galaxies are calculated and compared with field galaxies at similar redshifts. The cluster-averaged sSFR is also calculated. This study represents the largest sample of moderate redshift X-ray clusters to date and will provide insights into the evolution and efficiency of star formation in the cluster environment. [Preview Abstract] |
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E1.00023: A variable temperature virtual star for visual observing. Michael Braunstein Many visual observers, under appropriate conditions and albeit at low resolution, can qualitatively recognize the temperature sequence that is the basis of the MK stellar classification system. This is demonstrated by the well-known apparent color/temperature contrast of the binary star Albireo and a limited number of other bright, color-contrasting binary stars. We have developed a variable temperature virtual star, viewed through a telescope eyepiece, that permits an observer, in a manner similar to observing color-contrasting binary stars, to compare the color of a bright star to a virtual star whose apparent color can be varied corresponding to temperatures of the MK stellar classification system. The virtual star uses a pulse-width-modulated RGB LED, calibrated to vary in apparent color approximately along the Planck locus of the CIE color space, and coupled to an optical fiber which terminates at the focus of the telescope eyepiece. Preliminary results suggest that the virtual star is a qualitative, low resolution instrument which can be used to engage students in understanding the MK stellar classification system. [Preview Abstract] |
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E1.00024: Measuring the Effectiveness of a Peer Mentoring Program Samuel Steele Introductory level physics courses are important pre-requisites for college and university students. To insure the success of students in these courses at Montana State University (MSU), the Physics Department has established a Peer Mentoring Program (PMP) to support students taking their introductory physics courses. The peer-mentoring program consists of past students, or peer mentors, providing organized tutoring sessions to current students in a small group setting of six or less students. Groups meet twice a week for one hour sessions throughout the semester. Peer mentors are provided with weekly training on content, teaching techniques and information on what is currently being covered in class. A suite of materials developed at MSU, specifically for each of these courses, acts as resources for the peer mentor to use during sessions. To measure the effectiveness of the PMP, conceptual gains and shifts in attitudes of participating students was compared to the rest of the students enrolled in the courses. This was achieved by administering pre and post assessments using the Colorado Learning Attitudes About Science Survey and the Half Force Concept Inventory to the 1200 students taking introductory physics courses during the spring 2019 semester. End of the semester surveys were also collected from participants to provide additional information from participants in the PMP. [Preview Abstract] |
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E1.00025: Supporting and evaluating students’ written scientific explanations Margaret Ehrich, Tamar More We report on a study of students’ written scientific explanations (“narratives”) in the context of a general education physics course using the NextGen PET curriculum. Students wrote explanations several times during the course, given prompts with varying levels of scaffolding. We present a rubric for evaluating these written explanation for organization, completeness and correctness, a method for tracking these, preliminary data, and a discussion of the effectiveness of specific interventions. [Preview Abstract] |
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E1.00026: Applying the Energy Conservation Principle: Two Contrasting Reasoning Frames Luke Westbrook, Andrew Boudreaux The conservation principle is an important component of a model for energy. We have identified two frames, or approaches, that novices and experts seem to adopt when reasoning about energy conservation. The first, referred to as ``system-frame'' reasoning, involves defining a system, tracking energy inputs and outputs across the system boundary, and relating those transfers to an accumulation or depletion of the energy contained within the system. The second approach, ``energy-frame reasoning,'' involves identifying some initial amount of energy and ``following'' that energy as it transfers and transforms in a set of interactions, until that energy is fully accounted for. In this poster, we present examples of these reasoning approaches drawn from a set of interviews conducted with undergraduate physics majors. [Preview Abstract] |
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E1.00027: Student Understanding of Energy Concepts Across Disciplinary Boundaries Jessica Trottier, Alessandra Hughes, Brittany Moreno, Todd Haskell, Emily Borda, Sara Julin, Andrew Boudreaux In most undergraduate curricula, students are expected to have the ability to apply, or transfer, a learned concept to new coursework. In the sciences, students are often introduced to energy ideas with discipline-specific vocabulary and tasks which encourage compartmentalized, surface-level understandings of energy concepts. Our research investigates student transfer of energy ideas within a coherent science course series, where physics is the foundational course. Similar modeling tools and vocabulary are used in the classes to help students see energy as a unifying framework. We seek to identify and describe what transfer “looks like” in this idealized context by interviewing students enrolled in the next three science courses in the series. They are asked to describe and explain scientific phenomena they have not yet encountered, but to which it is possible to apply energy concepts from the prerequisite physics course. Our qualitative analysis focuses on the identification of the energy concepts students utilize during their reasoning process. We aim to better understand the resources students activate and the obstacles they encounter when attempting this transfer. [Preview Abstract] |
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E1.00028: ADHD Subtypes and Symptom Severity as Predictors of Motivation Intervention Outcomes. Yuya Xu This research project studies whether the ADHD subtype can predict the effectiveness of a motivational intervention for children with ADHD. The participants included parents and the 59 children aged 7-14 (mean age $=$ 10.13 years, female $=$ 28.8{\%}) officially diagnosed with ADHD. Children's ADHD diagnoses were determined by the parent report (ADHD C $=$ 21, ADHD IA $=$ 22, ADHD subtype not specified $=$ 16). Children participated in four small group motivational lessons where they were taught about growth mindset, neuroplasticity, coping strategies targeting frustration, and the potential of unique creative abilities of the individuals with ADHD. These lessons served to improve the children's beliefs about the malleability of the intelligence, personal self-efficacy and their emotional control abilities. At pre and post assessments, children completed two challenging tasks to evaluate their persistence --- a puzzle-building activity and a trivia questionnaire. Here we investigate whether children with ADHD combined type and children with ADHD predominantly inattentive type differed in their persistence from pre to post assessments. Analysis revealed no significant differences in persistence improvement between the ADHD-C and ADHD-IA groups on the puzzle task (p$=$.175) and the trivia task (p$=$.855), which suggests that ADHD subtype may not be a meaningful predictor of the effectiveness of motivational intervention. However, future analyses will account for missing data by using parents' reports on the BRIEF2 and Conners Parents Rating Scales which can be used to distinguish whether a child's symptoms are indicative of ADHD-C or ADHD-IA. Understanding whether ADHD subtype is predictor of intervention effectiveness will allow us to determine for whom the motivational intervention is most effective.. [Preview Abstract] |
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E1.00029: Establishing Norms of Behavior in Physics Courses Andrew Boudreaux, Regina Barber DeGraaff, Kevin Covey The practice of establishing explicit norms of behavior is becoming more common in college and university physics courses. Norms can support the active participation of students who might otherwise not participate, and serve as a foundation for an equitable, inclusive learning environment. In the Department of Physics and Astronomy at WWU, faculty and staff have been implementing a variety of approaches to engaging students in collaborative development of class norms. This work has been spurred in part by a recent, college-wide, NSF-supported project to advance student centered teaching practices (“Change at the Core”). This poster will describe norms, outline the potential benefits of explicitly establishing norms, and share some approaches to establishing norms in physics courses. [Preview Abstract] |
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