Bulletin of the American Physical Society
Annual Meeting of the Four Corners Section of the APS
Volume 59, Number 11
Friday–Saturday, October 17–18, 2014; Orem, Utah
Session F1: Poster Session |
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Room: Science Building Atrium |
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F1.00001: Comparing Two Methods Used in Calculating Acoustical Intensity Darren Torrie, Benjamin Christensen, Eric Whiting, Traci Neilsen, Kent Gee When measuring acoustical intensity the standard is usage of the finite difference method. This method however is not very reliable for high frequencies specifically above 2 kHz. A new method called the phase amplitude gradient estimator or PAGE method has been developed at BYU which in theory doesn't break down as frequencies increase. We have done several different intensity scan experiments that verify that the PAGE method is accurate and reliable at frequencies where the finite difference method fails. [Preview Abstract] |
(Author Not Attending)
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F1.00002: Metrology for Nanoscale Manufacturing Alexander Munoz The extension of optical techniques to the nanoscale is increasingly powerful because manufacturing requires fast, in-line, non-destructive metrology. As part of the NASCENT NSF Engineering Research Center led by the University of Texas at Austin, the focus of the effort is on the tools necessary for establishing manufacturing infrastructure required for process control of nanoscale printing. The initial exploration of scatterometry involved the use of a 244 nm laser to evaluate the zero-order reflectivity as a function of angle of incidence for two polarizations. Measurements of the wire-grid polarizer were then repeated with 405 nm to investigate the extensibility of scatterometry. In conjunction with the scatterometry data, rigorous coupled wave analysis simulations were used to determine the behavior of the reflectivity as a function of five critical dimensions. Varying the parameters led to the ability to fit the simulation curves to the experimental data, thus revealing the dimensions of the wire-grid polarizer. Grating profiles are established continuously allowing for the implementation of roll-to-roll manufacturing as envisioned by NASCENT. Scatterometry is a workhorse of Si lithography because of its fast, non-contact measurements at extreme sub-wavelength scales. [Preview Abstract] |
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F1.00003: Precision Measurements of Atomic Excited State Lifetimes Using Mode-Locked Femtosecond Lasers Jeremy Snell, Brian Patterson, Jerry Sell, Alina Gearba, Douglas Buchanan, Randy Knize Measurements of excited state atomic lifetimes provide a valuable test of atomic theory, allowing comparisons between empirical and calculated atomic matrix elements. However, as calculations have progressed, the most accurate direct lifetime measurements remain at the 0.1-0.2{\%} precision level, partly due to the nonlinearity and calibration in conventional timing electronics. We will present our progress toward precision excited state lifetime measurements in Rb where the timing is based upon the repetition rate of a mode-locked femtosecond laser. Our apparatus consists of counter-propagating atomic beams, which cross perpendicular to excitation and ionization laser beams. A chopped cw laser provides excitation to the relevant atomic state, while the output of a mode-locked laser is amplified and frequency-doubled to produce ionization pulses. We vary the delay between excitation and ionization by a multiple of the mode-locked laser period, resulting in an extremely accurate time base for future precision measurements. This presentation will highlight improvements to the apparatus aimed at reducing the error from the pileup of detected ion events. [Preview Abstract] |
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F1.00004: Exploring robust phase retrieval from noisy intensity interferometer measurements using a modern non-linear de-noising technique Elliot Myers, Peter Crabtree Various imaging techniques provide measurements proportional to Fourier magnitudes of an object, from which one attempts to form an image. One such technique is intensity interferometry, which measures the squared Fourier modulus. Intensity interferometry is a synthetic aperture approach known to obtain high spatial resolution information, and is effectively insensitive to degradations from atmospheric turbulence. These benefits are offset by an intrinsically low signal-to-noise (SNR) ratio. The fields of image processing and computer vision have produced advanced de-noising methods in recent years, such as BM3D and the bilateral filter. Here we explore the de-noising algorithm of Kovesi, as it was intentionally designed to be phase-preserving -- the quantity we aim to recover. Phase retrieval (PR) is designed to reconstruct an image from Fourier-plane magnitudes and object-plane constraints. In particular, we augment the relaxed averaged alternating reflections (RAAR) PR algorithm with the Kovesi de-noising method. We present simulated image reconstructions from the squared Fourier magnitude in the presence of significant noise --with and without the use of Kovesi de-noising as either a single pre-processing step, or an additional step within the RAAR iteration. Author info: C1C Elliot Myers (presenter), First Class Cadet at USAFA; Dr. Peter Crabtree -- research advisor at AFRL/RVBYC [Preview Abstract] |
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F1.00005: Analytically Evaluating Sums in Quantum and Statistical Physics Using Integral Transforms John Vastola Evaluating sums analytically is a problem that is easy to pose and to give approximate solutions to, but that is difficult to exactly solve in general. Many results that are known are byproducts of Fourier analysis, which requires guessing that a series corresponds to a function. A more systematic method of evaluating sums using integral transforms is proposed which can reproduce many results obtained using other techniques. In particular, representing polynomials as Laplace transforms gives some nontrivial exact results. Some applications of the method are demonstrated, and extensions of the method using integral representations of frequently appearing functions are suggested. One useful representation of the gamma function is supplied, and used to provide both well-known and more obscure results. Interestingly, the application of this integral representation to evaluating sums suggests the introduction of a novel integral transform, which itself can be used to evaluate sums. Some of the transform's properties are given, and its usefulness in other areas (like solving differential equations) is touched upon. Some physical problems involving the partition functions of statistical mechanics, and some infinite sums appearing in quantum mechanics, are considered. [Preview Abstract] |
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F1.00006: The effect of orbital dynamics on early Mars climate Gregory Colledge, John Armstrong In this research, we considered the impact of the orbital dynamics on the possibility of liquid water on Mars. The Nice II model of our solar system suggests that the giant gas planets migrated into positions of orbital resonance. Using an N-body simulator and a simple climate model, we put Jupiter and Saturn into various resonant orbits and observed the effects. We found that a 2:1 resonance had the highest chance of warming Mars enough to sustain liquid water on the surface. At the same time, liquid water would have been maintained on Earth. Future research efforts include observing the effects of the migration period, as well as the long term stability of the climates of Earth and Mars. [Preview Abstract] |
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F1.00007: FalconSAT-7--A deployable solar telescope Anita Dunsmore, Matthew McHarg The Physics Department at USAFA is the program integrator for FalconSat-7, an innovative mission to perform space-based imaging with a 0.2m diameter, photon-sieve telescope deployed from a 3U (10x10x30cm) CubeSat. The telescope will perform narrow-band imaging of the Sun's chromosphere at the hydrogen-alpha wavelength. The photon-sieve telescope relies on a new technology consisting of a deployable structure that supports an optical membrane called the photon sieve. The photon sieve is a flat diffractive element that consists of 2.5 billion holes, configured such that transmitted light is diffracted to a focal plane where a camera is located. As such, the technology is particularly promising as a means to achieve large optical primaries from compact, lightweight packages. We focus our discussion on the current status of the payload design and development to include the photon sieve, deployment system, optical bench, and payload electronics. [Preview Abstract] |
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F1.00008: Exploring Exomoon Habitability Using Python Geoffrey Warren Based on the life systems on Earth, one of the most basic limiting conditions for the existence of life on any celestial body is the existence of liquid water. ~There exist certain orbital boundaries around a star that can allow for these conditions on a planet. However, many stars have gas giants within these habitable zones that are not, by nature, suitable for life. This project explores the conditions that would allow for liquid water on a moon with a mass large enough to support an atmosphere and orbits around a gas giant within a star's habitable zone using a basic python-based climate model and orbital simulation. The scope of this project will eventually include the ability to use data from known star systems and simulate the optimal orbit of a life-supporting exomoon in that system. [Preview Abstract] |
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F1.00009: Developing a Low-cost NIR Imaging System to Introduce Students to Medical Imaging Techniques Ashleigh Wilson, Kim Nielsen At many institutions, the algebra-based introductory physics courses are populated with students specializing in biological fields such as preparation for medical or dental schools. While the main focus on the course is to provide the students with a solid conceptual understanding and solving problem skills in physics, the students often see little application towards their fields. This is particularly true in the traditional introductory physics laboratory experiments and demonstrations. As part of a summer research project, we explored the possibility of developing a low-cost NIR imaging system, which could be used in demonstrations, laboratory exercises, as well as student research projects. The use of infrared imaging in medical physics is an emerging technology with promising prospects, including thermography, biometry, and phlebotomy. For example, when using near infrared (NIR) light (700-1100 nm), vein imaging and mapping is possible. Due to the deoxidized nature of hemoglobin in veins, it exhibits strong absorption at a certain wavelength ($\sim$ 730 nm). Utilizing an array of different NIR wavelengths and a modified web camera, we successfully created a low-cost NIR imaging system capable of mapping out veins. This poster will present the instrument setup as well as show the preliminary results. Further potential use of this system will also be presented. [Preview Abstract] |
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F1.00010: Characterizing the Long-term Variability of X-ray binary 4U1705-44: Evidence for an Underlying Double-Welled Nonlinear Oscillator Rebecca Nichols 4U 1705-44 is a bright low mass x-ray binary (LMXB) containing a neutron star and a close, low mass companion. The Rossi X-ray Timing Explorer (RXTE) All-Sky Monitor obtained approximately 14 years of daily monitoring on 4U 1705-44 in the 2-20 keV energy range. Understanding the x-ray variability of 4U1705-44 is critical to the study of all low mas x-ray binaries because they share many of the same global characteristics in their high-amplitude transitions and non-periodic variability. After comparing the long-term light curve and phase space trajectories of 4U1705-44 to various nonlinear oscillators, the Duffing Oscillator was revealed to be a strong candidate to describe these systems. The parameters of the Duffing equation were optimized and six solutions sharing the same characteristics as 4U1705-44 were found. Striking commonalities were revealed via a phase-space analysis of both 4U1705-44 and the six Duffing solutions: the low-order driving period is no less than 87 days and spans up to 180 days, which is seen and highlighted in the power spectra, zero-crossings and close returns analysis of 4U1705-44. Furthermore, the driving frequency of all six Duffing solutions tend to converge to a range of 3.6 -- 4.5, corresponding to driving periods in the range from 130 to 175 days, in agreement with that found in 4U1705-44. Nonlinear analysis methods such as close returns and zero-crossings of the Duffing solutions also show the same trends. This strongly suggests that 4U1705-44 shares the same topological characteristics as the Duffing equation. [Preview Abstract] |
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F1.00011: Hermetic Nano-Bonding\texttrademark and Surface Characterization for Medical Implants and Marine and Air Sensors Ender Davis, Nicole Herbots, Shawn Whaley, Ross Bennett-Kennett, Robert Culbertson, Austin Causey, Rob Rhoades, Scott Drews, Clarizza Watson, J. ``Doc'' Bradley, David Sell, Peter Rez, Barry Wilkens Sodium percolation deteriorates diabetics' ``permanent'' glucose sensors in days. Nano-Bonding\texttrademark could allow them to last over two years. Nano-Bonding grows molecules between surfaces to create a hermetic bond, and has applications in single-device medical implants, marine and air sensors, solar panels, night vision goggles, and more. Nano-Bonding [1,2] uses $\beta $-cristobalite-like Si$_{2}$O$_{4}$H$_{4}$ on Si(100) as a precursor phase to cross-bond silica and Si across 20-30 nm-wide atomic terraces. Annealing occurs below 180 $^{\circ}$C under steam pressurization. The Herbots-Atluri process [1] nucleates precursor phases like Si$_{2}$O$_{4}$H$_{4}$, which react at low temperature. Si$_{2}$O$_{4}$H$_{4}$ reacts with hydrophilic, oxygen-deficient phases, forming cross-bonding inter-phases. Surfaces are characterized after each of these steps: forming the precursor phase, nano-contacting, Nano-Bonding, and de-bonding. Bonding strength correlates to topographies measured by Tapping Mode Atomic Force Microscopy, and 3 Liquid Contact Angle Analysis with the Van Oss theory. An atomistic model is proposed. [1] US patent 6,617,637 (2003), 7,581,365 (2010). [2] N. Herbots et al. Pub. No 13/259,278, PCT/US2010/033301 (2012). [Preview Abstract] |
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F1.00012: Constraints on Synchrotron Radiation from Dark Matter Annihilation in Dark Star Remnants David Stephens The particle nature of dark matter is currently one of the largest unanswered questions in astrophysics. To probe the properties of dark matter, we will look at the synchrotron flux from dark matter annihilation in dark star remnants. In the early universe, the presence of dark matter has been shown to delay the ignition of nuclear fusion during star formation, resulting in large ``dark stars'' that can collapse to black holes. Each of these black holes will be surrounded by a highly dense area of dark matter, where dark matter particles annihilate to produce charged particles. In turn, the charged particles interact with magnetic fields producing synchrotron radiation. By summing the synchrotron flux across the entire population of dark star remnants and taking redshift into account, the observable synchrotron flux today can be estimated. Specifically, we examine the synchrotron flux from Weakly Interacting Massive Particles (WIMPs) as the candidate for dark matter across two annihilation spectra, 150 GeV WIMPs to $W^+ W^- $ and 600 GeV WIMPs to $\tau^+\tau^-$. Comparing the predicted synchrotron flux to observation, constraints can be placed on dark star remnants as a source of dark matter annihilation and on the WIMP mass and annihilation cross section. [Preview Abstract] |
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F1.00013: Pair Distribution Function Analysis Applied to Multiply-Twinned Gold Nanoparticles Corinne Silkwood, Heinz Nakotte, Edwin Fohtung, Katharine Page, Hsui-Wen Wang, Graham King Pair distribution function (PDF) analysis is a statistically based method of structure determination which investigates the correlation of atomic positions within a sample. Motivated by electron microscope images of gold nanoparticles with non-crystallographic morphologies and the possibility of studying their structure with PDF analysis, three computer models were created. The particles exhibit five-fold symmetry inconsistent with a continuous crystal lattice and generally explained by multiple twinning of a tetrahedral subunit about a symmetry axis, with or without structural modification to the crystal lattice. In cubic structures, five-fold twinning results in a particle with a solid gap; small lattice deformations produce a spatially continuous particle with orthorhombic structure. These alternative geometries, and a hybrid configuration, were modeled. PDF data was simulated for the model particles with the objective of determining sensitivity to twinning and lattice distortion. The simulated data reflects structural characteristics of the models including deformations of lattice parameters on the order of tenths of Angstroms. Subsequent experimental PDF analysis of these particles showed agreement with a twinned cubic lattice model. [Preview Abstract] |
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F1.00014: Tunable Processing of Chalcogen-Hyperdoped Silicon Kaz Moffett, Randy Knize, Reni Ayachitula, Kimberly de La Harpe, Noah Blach, Daniel Weisz We will present studies on samples of chalcogen-hyperdoped silicon produced using a tunable process, allowing for the systematic variation of sulfur content within silicon. Hyperdoping silicon with sulfur leads to increased absorption in the infrared region, making it of interest for application in solar technology and infrared detection. Future work involves adapting this tunable method to be scalable and cost effective. [Preview Abstract] |
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F1.00015: A Dual-defect Model for Predicting Lifetimes for Polymeric Discharges from Accelerated Testing Allen Andersen, JR Dennison Electrostatic discharge (ESD) can cause catastrophic failures in electronic devices. Estimating the lifetime of dielectrics under prolonged high field exposure is a major design concern for applications including spacecraft, high voltage DC power transmission, and semiconductor electronics. Dielectric strengths listed in engineering handbooks are primarily based on cursory measurements with poor repeatability and tend to overestimate ESD fields in real applications. Standard measurements subject test samples to $\approx $500 V/s ramp rates until breakdown. We present the results of ESD studies in two prototypical polymer dielectrics using a ramp rate of $\approx $20 V/4s until breakdown, together with tests applying a static voltage and directly observing time-to-breakdown. Prior to ESD, transient current spikes, termed pre-arcs, were also observed. The results of these tests are explained in terms of a physics-based model of defect creation within the material from bond stress due to applied electric fields. A first order approximation is presented to develop an extended temperature- and ramp rate-dependent ESD model with both repairable and irreparable defect mechanisms. Repairable defects such as bond bending have energies on the order of thermal energies so that they can be readily repaired through thermal annealing; irreparable defects such as bond breaking have higher energies. We discuss how defect energies and densities, extracted from the results of accelerated laboratory tests, can be used to estimate fields with a satisfactory probability of material lifetimes of many years. [Preview Abstract] |
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F1.00016: Cathodoluminescence Events Coincident with Muon Detection Kenneth Zia, Justin Dekany, JR Dennison Samples of highly disordered insulating material were irradiated with 1 keV electron beams, resulting in three forms of light emission with differing duration: arcs (\textless 1 s duration), flares ($\sim$ 100 s), and cathodoluminescence (as long as beam is on). The arc and cathodoluminescence phenomena are well understood, while the flares are not. Flares were observed at intervals of $\sim$ 2 per hr. This is within a factor of 2 for the expected muon cross-section at an altitude of Logan, UT (1370 m) caused by high altitude cosmic rays. Based on this suggestive evidence, we have proposed incorporation of standard muon coincidence detection apparatus into our vacuum cathode luminescence test facility. Measurements of the muon cross-section zenith angle and angle-dependence will provide calibration of the muon detector. If muon evidence coincides with the flare events, this will provide definitive evidence of the flare origin. We will discover whether a correlation between flares of charged sample are caused by transitory muons which trigger discharge and subsequent recharging during our testing of space materials. [Preview Abstract] |
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F1.00017: Breakdown Analysis of Electrostatic Discharge Samuel Hansen, Allen Anderson, JR Dennison Material breakdown due to Electrostatic discharge (ESD) is the primary cause of spacecraft damage due to environment interactions in space. This occurs when the space plasma fluxes charge a craft to high voltages where insulating craft materials then break down. This failure allows current to flow freely through the material, this can damage or destroy onboard electrical systems. My project focuses on the effects of these breakdowns on suspect materials commonly used for electrical insulation in space. The USU Material Physics Group has performed ESD tests on hundreds of samples to date. The ESD damage sites of these samples have been analyzed for parameters including breakdown size, shape, location, thickness, and polymer type. The results have been recorded in an updatable ESD Quality Summary Table. Our table can be sorted internally, and is linked to the breakdown images. Initial trends within this data set are being indentified and sorted based on experimental parameters in order to locate more trends. This data will aid in predicting which materials are best suited for use in high voltage scenarios found in space charging events. [Preview Abstract] |
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F1.00018: Space Effects Survivability Testing Lisa Phillipps, JR Dennison, Kent Hartley, Robert Johnson, Justin Dekany, James Dyer A versatile test facility has been designed to study the effects of space environment fluxes and radiation damage on small scale materials samples, system components, and small satellites. Cost-effective long-duration testing for potentially environmental-induced modifications is increasingly more important as small satellite programs have longer mission lifetimes, expand to more harsh environments, make more diverse and sensitive measurements, minimize shielding to reduce mass, and utilize more compact and sensitive electronics. The facility simulates environmental components including the neutral gas atmosphere, the solar spectrum, electron plasma fluxes, and temperature. The UV/VIS/NIR solar spectrum is simulated using a class AAA Solar Simulator with up to four Suns light intensity. Far ultraviolet radiation is provided by Kr discharge line sources also with up to four Suns intensity. A low-energy electron flood gun provides a uniform, monoenergetic (20 eV-15 keV) electron flux. A medium-energy (20-100 keV), low-flux electron source uses filament-free photoemission. A Sr-90 $\beta $ radiation source produces a high-energy spectrum similar to the geosynchronous spectrum. A stable, uniform temperature range from 100-450 K is achieved using a cryogenic reservoir and resistance heaters. A data acquisition system periodically records the environmental conditions, photographs, UV/VIS/NIR reflectivity, IR absorptivity/emissivity, and surface voltage of the sample surface and in situ calibration standards in the chamber. [Preview Abstract] |
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F1.00019: Novel Bialkali Photocathodes for Ring Imaging Cherenkov Detectors at the EIC Gregory Ottino, Ashley Roach The Electron-Ion Collider (EIC) will be the next facility designed to explore the structure of the proton and of nuclei at the very smallest scales. Given that the EIC is at least ten years away, it is a good time to investigate new detector techniques that could be employed at such a facility. We have begun a program of research to investigate bialkali photocathodes (Gallium Arsenide or Gallium Arsenide Phosphate) for use with GEM or MCP electron multiplication systems which could be used in large-area Ring-Imaging Cherenkov (RICH) detectors at the EIC. The work on characterizing the quantum efficiency of these photocathodes is in its preliminary stages, and we will report on our progress to date. [Preview Abstract] |
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F1.00020: The Geometry Underlying Electromagnetism Scott Alsid, Mario Serna Geometry is often characterized by parallel transporting a vector along a closed path, where the curvature is proportional to the angle change after transport around the loop. This is the curvature used in General Relativity. This talk will explain how curvature relates to E{\&}M. In this talk, I will show three superficially different schools for manifesting this geometry to represent E{\&}M. I will describe how to make rigorous the ``rings'' used by Brian Green to depict Kaluza-Klein theory. I will describe how to visualize curvature of E{\&}M fields with Grassmanians using a technique developed with Prof Cahill in the 2000s. Last, I will connect these representations to work done at MIT on a hidden spatial geometry of Yang-Mills theory of which E{\&}M is a special case. We will also discuss the relationship between the Grassmanians of elementary electric field arrangements and the spin-less wave function of an electron with regards to a deeper meaning of Gauss's Law. [Preview Abstract] |
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F1.00021: The effect of finite impedance ground reflections on horizontal full-scale rocket motor firings Samuel K. Hord, Tracianne B. Neilsen, Kent L. Gee Ground reflections have a significant impact on the propagation of sound from a horizontal rocket firing. The impedance of the ground relies strongly on effective flow resistivity of the surface and determines the frequencies at which interference nulls occur. For a given location, a softer ground, with lower effective flow resistivity, shifts the location of interference nulls to lower frequencies than expected for a harder ground. The difference in the spectral shapes from two horizontal firings of GEM-60 rocket motors, over snowy ground, clearly shows this effect and has been modeled. Because of the extended nature of high energy launch vehicles, the exhaust plume is modeled as a partially correlated line source, with distribution parameters chosen to match the recorded data sets as best as possible. Different flow resistivity values yield reasonable comparisons to the results of horizontal GEM-60 test firings. [Preview Abstract] |
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F1.00022: Bone Lead Levels for Subjects in Utah Ethan Kendall, Michelle Arnold Lead is a toxin known to cause neurological damage. High levels of lead exposure can lead to heart disease, high blood pressure, renal disorders, birth defects, and an increased risk of delinquent behavior. Through the use of X-ray fluorescence (XRF) and gamma spectroscopy, lead concentration in subjects' right tibia and left calcaneus are measured. The relationship between lead concentration and demographics such as age, gender, height, weight, and years lived in Utah will be explored. [Preview Abstract] |
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F1.00023: Electron Impact Ionization of Neutral Particles Using Carbon Nanotubes Gregory Copeland, Gabriel Font-Rodriquez, Geoff McHarg, Elizabeth Mitchell, Tomek Kott We study the production of electrons using a thin two dimensional carbon nanotube array. We apply a potential of several hundred volts to the nanotube array to produce the electrons. We examine the electron current produced from the array as a function of applied voltage and the electron current versus time at one applied voltage. The electrons produced will be used in the detection of neutrals species in low Earth orbit by electron impact ionization of the neutral species followed by collection of the resulting ions. We theoretically investigate the predicted ionization rate and ion density as a function of electron current in a chamber with neutral particle densities appropriate to low Earth orbit. [Preview Abstract] |
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F1.00024: Recent Investigations of the Statistical Characteristics of Mesospheric Gravity Waves Over Antarctica Joseph R. Jepson, Mike J. Taylor, P.-Dominique Pautet The Antarctic Gravity Wave Instrument Network (ANGWIN) is a National Science Foundation (NSF) sponsored international program designed to develop and utilize a network of gravity wave observatories using existing and new instrumentation operated at several established research stations around the continent. The primary goal is to better understand and quantify gravity wave climatology and their effects on the upper atmosphere around the Antarctic continent. ANGWIN currently comprises research measurements from five nations (U.S., U.K., Australia, Japan, and Brazil) at seven international stations. Utah State University's Atmospheric Imaging Lab operates all-sky infrared and CCD imagers and an Advanced Mesospheric Temperature Mapper (AMTM) imager at Davis, Halley, Rothera, McMurdo, and South Pole research stations. In this poster we present an analysis of recent measurements of short-period mesospheric gravity waves imaged from Rothera Station (67.57 $^{\circ}$S, 68.12 $^{\circ}$W) on Adelaide Island. This camera has operated continuously at Rothera since 2006 and the new results combined together with coordinated measurements from the other sites will significantly improve our understanding of the large scale dynamics of gravity waves and their regional variability. Here we present image results from 2012. [Preview Abstract] |
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F1.00025: Ground to stratosphere \textit{in situ} ozone measurements for determining ozone sinks and sources Johnny Nikoloff, Erika Mueller, Jeffery Page, Ian Hardy, John E Sohl The Weber State University HARBOR program has been conducting balloon launches to collect \textit{in situ} atmospheric data from ground level to the lower stratosphere. A primary focus has been on improving the calibration process to meet the standards of the World Ozone and Ultraviolet Data Center. The results have allowed us to calibrate previous measurements and start the characterization of a solid state ozone sensor as part of a wide spectrum gas sensing package that is also under development. In an ideal atmosphere there would be no significant ozone concentrations except in the stratospheric ozone layer. In Utah's Uintah Basin we are detecting two additional layers. One at ground level and one near the tropopause. Ground level ozone is likely pollution from vehicle traffic, although extensive fracking activity might also be a contributor. The next layer is possibly due to commercial jet traffic, except that the layer is just above normal flight levels. This could be a shift caused by atmospheric turbulence. Utah's Salt Lake Basin has air quality problems involving ozone in the summer; some fraction of that ozone is related to Great Salt Lake (GSL). It is probable that a chemical process is taking place due to the high concentration above GSL of NaCl particles that may be reacting with UV light to create more ozone. Using the ozonesonde and/or the solid state ozone sensor might allow us to characterize the ozone source and sink behavior of GSL. Initial characterization of these sensors has been completed. [Preview Abstract] |
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F1.00026: Atomic Cross Sections and Photoelectron Secondary Ionization in the E- and F1-Layers of the Ionosphere Maggie Lewis, Jan Sojka The main driving force for the creation of the ionosphere is solar irradiance. High energy photons from the sun ionize neutral atoms in the atmosphere and create free photoelectrons. Not every photon-atom interaction will result in ionization. The likelihood of a photon ionizing an atom is described by the atomic cross sections. The rate of photoelectron production depends on the interaction cross section. The higher the energy of a photon, the greater the photoelectron energy will be. As such, high energy photons (UV and soft X-ray) emitted by the sun have a greater chance of ionizing and creating photoelectrons in the E-region and lower F1-region. If these free photoelectrons have a sufficient energy, they can cause additional ionizations. An energy of 35 eV is currently accepted to be the approximate value at which photoelectron secondary ionization can occur. The Time Dependent Ionospheric Model (TDIM) can simulate the ionosphere using solar irradiance data collected by NASA's Solar Dynamics Observatory (SDO) Extreme Ultraviolet Variability Experiment (EVE). By regarding the photoelectron secondary ionization energy as a free parameter, the accuracy of the 35 eV energy factor, along with other energy factors, can be examined at different altitudes. [Preview Abstract] |
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F1.00027: The impact on a physics-based model of the Earth's polar ionosphere resulting from uncertainties in the alignment of two empirical models David Hansen, Robert Schunk, Jan Sojka, Lie Zhu This presentation discusses the difficulties associated with the simultaneous use of two specific empirical models when modeling the Earth's polar ionosphere. In this study, the two empirical models were used to provide input that is required by a physics-based model of the Earth's polar ionosphere. However, there is uncertainty in how to align the two empirical models over the polar cap in a manner that adequately represents what is observed in nature. In this study it is shown that the uncertainty of aligning the two empirical models has a large impact on the physics-based model of the Earth's polar ionosphere. This study quantifies this impact and demonstrates the inadequacy of this procedure for forecasting applications. [Preview Abstract] |
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F1.00028: Suppressed concentration fluctuations in rat basophilic leukemia cell synapse: (indirect) evidence for large signaling complexes Rachel Drawbond, James Thomas, Kathrin Spendier The spatial extent of membrane receptor signaling complexes can be difficult to determine. Using a concentration fluctuation signature, we show an indirect way of determining the size of the IgE-Fc$\varepsilon $RI receptor signaling complex (IgE-RC) in rat basophilic leukemia (RBL) cells. This approach applies the concept that at high IgE-RC area fractions, randomly placed complexes cannot obey Poisson statistics, due to excluded area. When IgE-loaded RBL cells interact with a supported lipid bilayer (SLB) presenting binding ligands, IgE-RCs coalesce to form a large central patch called the mast cell synapse.~RBL cells labeled with varying concentrations of fluorescent and dark anti-DNP IgE settled onto SLBs with 25 mol{\%} DNP-lipid. Using TIRF microscopy, synaptic patches were imaged. At high fractions of fluorescent IgE, the spatial variance of the fluorescence fluctuations was observed to be suppressed, compared to the variance expected from Poisson statistics. Comparison of experiment to computer models suggest that the actual size of IgE-RC is at least two times larger than reported in literature, indicating that additional cytosolic or membrane proteins may associate with IgE-RCs. [Preview Abstract] |
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F1.00029: Strategies for Fluorescence Correlation with Photosensitive/Low-Yield Probes to Measure Receptor Dimerization Alexandria Doerfler, James Thomas Fluorescence Correlation Spectroscopy (FCS) is a well-established technique used to measure diffusion coefficients and concentrations of fluorescently labeled particles. If two distinct fluorescent labels are used with two detection channels, FCS can also measure particle-particle association, such as protein dimerization. Photobleaching adversely affects the measurement of associations: both the fluorescence signal and the fraction of dual-labeled receptor dimers are not stationary during the course of the measurement, but decay over time. We have adopted three strategies to deal with these difficulties. First, total internal reflection illumination is used to reduce background, allowing for dimmer illumination and lower count rates. Second, we make a direct measurement of photon counts in both channels (rather than using real-time correlation.) Third, a dynamic estimate of dimer concentration is made using very short measurement intervals (properly accounting for the large uncertainties in measurement) followed by fitting to a model that includes photobleaching effects.~The design and calibration of the microscope will be described, along with proof-of-principle model fitting. [Preview Abstract] |
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F1.00030: Wavelength Detection from Filtered Photodiodes Nils Otterstrom, Tyler Jones, Jarom Jackson, James Archibald, Dallin Durfee Filtered photodiodes show potential as an inexpensive and robust method for determining the wavelength of single frequency light. Photocurrents are measured digitally using externally controlled integration times to achieve the highest precision possible from the digital to analog converters on the photosensor chip. Using an algorithm we've developed and calibrated intensity curves, we can precisely calculate wavelength from the output of the different photodiodes. Limitations and possible improvements due to etaloning in the filters have been analyzed and effectively utilized, allowing the device to achieve remarkable precision with a stability of 0.01 nm over 70 hours. [Preview Abstract] |
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F1.00031: Power Line Error Analysis by Synchronizing Remote Signal Phase Measurements using High Precision Time-Stamped Telemetry Tim Wendler, Tyler Baker When an electrical utility crew wants to replace a section of high voltage electrical cable, phase references must be made on the old cable and transferred to the new cable. If these references are lost, or damage to the cable did not allow for references to be established, then the cable must be spliced and arbitrarily placed on an open, energized switch. The new cable is then energized and a phasing meter is used to find matching phases. The cable is then de-energized and the cables are moved to the appropriate locations on the switch. By adding an additional device to the phasing meter, a reading is taken of the phase and the device passes this reading as well as a high precision time-stamp wirelessly to a remote location where this reading can be compared against readings from other locations. This method will allow for positive identification of relative phases without the need of an initial energizing of the cable in question. This will save time, as well as reduce customer outages, prevent situations in which the spliced cable will not reach (i.e. the short cable must be moved to the long cables position on the switch), and lower the risk of a cross-phase fault. [Preview Abstract] |
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F1.00032: Violating the Uncertainty Principle: A Review Jacob J. Collings, Jean-Francois S. Van Huele We review the difference between two uncertainties: the \textit{preparation }uncertainty, which involves states and observables and the \textit{measurement} uncertainty, which also incorporates the evolution implied in a physical measurement process. We explore the proposed concepts of \textit{error} and \textit{disturbance}, which enter the measurement uncertainty and review recent experiments showing evidence for a violation of this \textit{measurement} uncertainty. We examine selected proposed reformulations of the measurement uncertainty relation and evaluate how closely they approach the experimental data. [Preview Abstract] |
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F1.00033: Teaching Vector Analysis to the Computer Rebecca Petrick, Charles Torre \textit{Differential Geometry }(DG) is a Maple software package which symbolically performs fundamental operations of calculus on manifolds, differential geometry, tensor calculus, Lie algebras, Lie groups, transformation groups, jet spaces, and variational calculus. In physics, DG has been used principally for research and educational activities in relativity and field theory. Using DG, we have developed a suite of commands for vector analysis in three dimensions. These commands allow one to easily compute the gradient, divergence, cross product, curl and Laplacian in \textit{any} three dimensional coordinate system, and even for curved three-dimensional geometries. We have built a digital library of the most popular 14 orthogonal coordinate systems in Euclidean space. Using this library, we have computed all the relevant vector operations, and corrected some errors in common literature. [Preview Abstract] |
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F1.00034: Self-replicating Structures in Dynamical Systems that Perform the Majority Task David Griffin, David Peak Collective dynamics in networks can perform complex tasks. An intensively studied toy example is the ``Majority Task,'' which is a simple model for aspects of emergent coordination and error correction in colonial organisms, social swarms, and communication networks. In the majority task spatially distributed units with two possible states are supposed to collectively evolve from a mixed initial state configuration to a uniform final configuration. When the task is performed correctly the final unit state is the one that was initially in the majority. These networks have no memory or central controllers, so the task is performed solely by unit-unit interactions. How this is accomplished and how it fails is not well understood. In the 2D version examined here, the units interact with only nearest neighbors through the very effective ``2DGKL'' dynamical rule. Rigorous studies of the evolution of 15x15 networks with approximately 50-50 irregular distributions of initial states, have discovered system-spanning, self-replicating structures that form early in the process. Units adjacent to self-replicating structures quickly become part of a larger self-replicating structure until the network reaches its final state. As a result, these structures can be used to predict the outcome of a network. The existence and significance of self-replicating structures is a new insight into the majority task and understanding how they form might be key to decoding and improving how the task is performed. [Preview Abstract] |
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F1.00035: Effect of x-rays of different wavelengths on the mortality of insects Ramaninder Brar, Jacob Urquidi Sterile Insect Technique (SIT) has been successfully used to eradicate insect populations. Different sterilization methods, ranging from chemo-sterilization to genetically modified male-sterile mosquito strains have been used, though sterilization with ionizing radiation from radioisotopes is the method of choice for effective sterilization for most species. Irradiating can result in high mortality rates and a decrease in competitiveness. New protocols for sterilization are needed to achieve a high percentage of sterility with few detrimental effects reducing breeding fitness. We have investigated the effect of x-rays of varying wavelengths on x-ray sterilized mosquito males. Our results suggest that wavelengths used during irradiation have a significant impact on males' longevity. The longer wavelength exposure delivered by the copper target shows a substantially steeper death rate than that delivered by the molybdenum target (shorter wavelength). We are currently studying the effect of different wavelengths of fluorescence-induced x-rays on insect mortality, and designing a simple, safe, economical x-ray device for SIT in remote areas. [Preview Abstract] |
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F1.00036: Solar Abundances in the Open Cluster M67 Parker Holzer The open cluster M67 has been one of the most studied star clusters in our galaxy, mostly because it is located fairly close to our Solar System and contains stars that are very similar to our Sun. However, there have been many disagreements over the solar composition of this cluster, and how abundant certain metals are in it. If we are to understand these abundances more fully we could further understand how this cluster formed, which would allow us to further understand the environment that our Sun was probable to have been formed in. The purpose of this project is to use many spectrum and stellar parameters recently derived by APOGEE to both measure the equivalent widths and metallicity of individual stars in M67. The anticipated outcome of this project is that we will get more precise measurements of the metal abundances, to more accurately understand their origin. [Preview Abstract] |
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F1.00037: Rejuvenated or Young? What is the Origin of These Ostensibly Old Stars? Dan Filler, Inese Ivans We have investigated a unique class of stars known as blue metal-poor (BMP) stars. These stars have been found in globular clusters (GC), where they are known as ``blue stragglers'' as well as in the halo of the Milky Way Galaxy (MW). There are two likely origins for these unlikely stars. In GCs, where stellar densities are 1000 times higher than the stellar density of the solar neighborhood, the crowded conditions lead to close encounters and stellar collisions, and in some cases, coalescence. The resulting more massive star is hotter and bluer. While this phenomenon explains the presence of blue stragglers, it does not account for the presence of BMP in the sparsely populated regions in the halo of the MW. It is possible that we are observing relatively younger stars that originated in dwarf galaxies captured by the MW. Stars in dwarf galaxies are often found to possess low abundances of elements formed in supernovae. In contrast, blue stragglers are often rich in elements produced by slow-neutron capture processes in intermediate mass stars. In this talk, I will present the status of this study: the stellar chemical compositions we have derived, the BMP categorizations, and the implications that these have on the construction/evolution of the stellar populations in the MW. [Preview Abstract] |
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F1.00038: Stomatal Physics Kathryn Sweet, Keith A. Mott, David Peak Stomata, microscopic pores on a leaf's surface, regulate the diffusion of CO2 from, and the diffusion of water vapor to, the air. As a result, stomata are responsible for fixing essentially all carbon in the biosphere and generating almost all water vapor in the atmosphere over landmasses. Despite their profound importance, exactly how stomata respond to temperature, light intensity, and ambient CO2 and humidity, is still a matter of active debate. Most research probing this question focuses on identifying and unraveling complicated biochemistry. Recent investigations in our laboratory, however, indicate that much of stomatal behavior can be understood in terms of a simple vapor phase physical model. Evidence supporting this claim includes: isolated stomata respond to changes in the surrounding humidity identically to how they respond in intact leaves; isolated stomata do not respond to changes in light or CO2, but when brought close to, though not in contact with, mesophyll cells (where photosynthesis occurs), they do respond to both; and isolated stomata open and close when exposed, respectively, to positive and negative vapor phase ions. Ongoing work using state-of-the-art high-resolution thermal imaging and confocal microscopy to further test the hypothesis that stomatal responses to environmental conditions are largely due to just vapor phase physics will be described. [Preview Abstract] |
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F1.00039: Thermal Analysis of Silicon-Carbide Power MOSFETs Dmitry Panin State-of-the-art, commercially available, Silicon-Carbide (SiC) Power MOSFETs were evaluated and tested for stability under different temperature, gate voltage, and drain voltage configurations. The operational characteristics of various outer space conditions, namely high elevated temperature and long accumulation time were simulated in order to prepare the transistors for space travel applications. Collected data showed that these transistors are quite temperature durable, requiring smaller heatsinks than traditional Si Power MOSFETs, making them a good candidate for spacecraft use, specifically for the PPU (Power Processing Unit) used to converts energy generated by a solar array for onboard high power electronics such as the ion drive, replacing conventional (Silicon) transistors which are less able to withstand high voltage {\&} high current burst scenarios at elevated temperatures. [Preview Abstract] |
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F1.00040: General Relativistic Effects on Kepler Systems Taylor Morgan, Jared Jay, David Neilsen The Kepler satellite has observed several extra-solar planetary systems. The masses of the planets are determined from their observed cross sectional area; and the density is inferred from a stability analysis of the planetary systems using Newtonian gravity. Using post-Newtonian equations, we explore how general relativistic effects alter the stability properties of planetary systems, and possible changes to the inferred masses of the Kepler planets. We also explore the chaotic nature of 3-body systems in general relativity. [Preview Abstract] |
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