Bulletin of the American Physical Society
10th Annual Meeting of the Northwest Section of APS
Volume 53, Number 6
Thursday–Saturday, May 15–17, 2008; Portland, Oregon
Session C1: Poster Session (5:00 p.m.-6:00 p.m.) |
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Chair: Kara Keeter, Idaho State University Room: Templeton Fields Dining Hall |
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C1.00001: Nonlinear Stability Analyses of Optical Pattern Formation in an Atomic Sodium Vapor Ring Cavity. David Wollkind The development of spontaneous stationary equilibrium patterns induced by the injection of a laser pump field into a purely absorptive two-level atomic sodium vapor ring cavity is investigated by means of various weakly nonlinear stability analyses applied to the appropriate governing evolution equation for this optical phenomenon. In the quasi-equilibrium limit for its atomic variables the mathematical system modeling that phenomenon can be reduced to a single modified Swift-Hohenberg nonlinear partial differential time-evolution equation describing the intracavity field on an unbounded two-dimensional spatial domain. Diffraction of radiation can induce transverse patterns consisting of stripes, squares, and hexagonal arrays of bright spots or honeycombs in an initially uniform plane wave configuration. Then these theoretical predictions are compared with both relevant experimental evidence and existing numerical simulations from some recent nonlinear optical pattern formation studies. [Preview Abstract] |
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C1.00002: Experimental Realization of an Optical One-Way Barrier for Neutral Atoms Tao Li, Jeremy Thorn, Elizabeth Schoene, Daniel Steck We demonstrate an asymmetric optical potential barrier for ultracold $^{87}$Rb atoms using laser light tuned near the $D_2$ optical transition, which could be a promising general method of laser cooling and trapping applicable to atoms and molecules not amenable to standard laser-cooling techniques. In addition, the one-way barrier, where atoms impinging on one side are transmitted but reflected from the other, is a literal realization of Maxwell's demon. In our experiment, atoms are confined to a far-detuned dipole trap consisting of a single focused Gaussian beam, which is divided near the focus by the barrier. The one-way barrier consists of two focused laser beams oriented almost normal to the dipole-trap axis. The first beam is tuned to have a red (blue) detuning from the $F = 1\rightarrow F'$ ($F = 2 \rightarrow F'$) hyperfine transitions, and thus presents a barrier only for atoms in the $F = 2$ ground state, while letting $F = 1$ atoms pass. The second beam pumps the atoms to $F = 2$ on the reflecting side of the barrier, thus producing the asymmetry. We study experimentally the reflection and transmission dynamics of ultracold atoms in the presence of the one-way barrier. [Preview Abstract] |
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C1.00003: Electromagnetically induced transparency in rubidium: An advanced undergraduate laboratory Shannon Mayer, Abraham Olson Electromagnetically induced transparency (EIT) can be used to modify the optical response of an atomic medium to a resonant laser field. In EIT, a non-resonant pump laser beam can result in the reduction of absorption of a weak, resonant probe laser beam, provided the fields are coherently coupled by a common state. EIT provides a unique means of coherently controlling photons and has potential applications in fields ranging from quantum computing to telecommunications. In this advanced laboratory we describe the theory and experiment for investigating ladder-type EIT in rubidium gas. The theoretical absorption profile of a weak probe laser beam tuned across the 5S 1/2 to 5P 3/2 transition (780.2 nm) is modeled in the presence of a strong coupling laser beam tuned to the 5P 3/2 to 5D 5/2 transition (776.0 nm) and the absorption transparency window is characterized. Using grating-feedback diode lasers, we observe EIT experimentally in rubidium gas and compare the results to the theoretical model. Applications of EIT to high-resolution two-photon spectroscopy are also discussed. This laboratory uses much of the same equipment as the saturated absorption experiment commonly performed on the D2 line in rubidium, so it is easily implemented in laboratories with the equipment to conduct that experiment. [Preview Abstract] |
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C1.00004: Multiscale Modeling of Polymer Liquids Ivan Lyubimov, Marina Guenza For polymer systems, the time and length scales where relevant phenomena take place encompass a large range. Theoretical approaches and computer simulations are limited. The effective way to investigate polymer systems is to coarse-grain and apply multiscaling procedure. Using the Ornstain-Zernike relation we derived an analytical way to coarse-grain the structure of polymer liquids (homopolymer melts, block copolymers, and polymer mixtures) to the different length scales. The effective pair potential between coarse-grained units is an input to the mesoscale computer simulation. Outputs from the united atom simulation and mesoscale simulation are combined in an original multiscale procedure providing information at all length scales of interest, which substantially saves computational time. Rescaling the output of mesoscale simulations allow us to describe the dynamics of a system in the complete range of timescales of interest. [Preview Abstract] |
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C1.00005: Rubidium Cloud Size in a Magneto-Optical Trap A. Chatwin-Davies, T. Kong, J. A. Behr, A. Gorelov, M. Pearson Preparations for a search for exotic 20 - 556 keV-mass particles emitted during the nuclear 2-body decay of $^{86}$Rb confined in a magneto-optical trap (MOT) are underway at TRIUMF. Such emissions would correspond to a peak in the recoil momentum distribution at a momentum lower than that caused by 556 keV $\gamma$ emission. The stable isotope $^{85}$Rb is being used to optimize the experimental apparatus since its atomic hyperfine splitting is similar to that of $^{86}$Rb, producing similar laser cooling properties. The size of the cloud of trapped atoms directly affects the achievable momentum resolution of the recoil and must hence be minimized. A Doppler-limited model for cloud size ignoring cooling beyond that generated by the photon scattering force is presented and compared with experimental data. Analysis suggested reducing the intensity and red-detuning from resonance of the trapping light from optimal values for atom collection. We also better balanced the power in the trapping beams. Recent data in disagreement with a Doppler-limited theory indicate sub-Doppler cooling mechanisms (J. Dalibard and C. Cohen-Tannoudji, J. Opt. Soc. Am. B 6, 2023 (1989)) are now at work. A cloud full width at half-maximum of less than 0.25 mm has since been achieved. [Preview Abstract] |
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C1.00006: Chaos Synchronization and Communication using Optoelectronic Time-Delay Feedback Circuits Christopher May, Lucas Illing We investigate experimentally a chaos communication scheme that is based on the synchronization of two optoelectronic circuits. Oscillations with frequencies of up to 10 GHz are generated in a single circuit by means of time-delayed and amplified feedback to a laser-pumped optoelectronic Mach-Zehnder modulator that serves as the nonlinearity. By varying the pump-laser power the device dynamics can be tuned from simple periodic to highly chaotic oscillations. Synchronization is achieved by unidirectionally coupling two circuits via a fiber-optic link and by matching them through fine-tuning the pump-laser powers and Mach-Zehnder bias voltages. Using these synchronized optoelectronic circuits we demonstrate communication by adding a message signal to the transmitter and successfully retrieving it from the chaotic carrier signal at the receiver. [Preview Abstract] |
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C1.00007: Fabrication of Barium Ferrite Thick Films Wei Jiang Yeh, Carla Blengeri-Oyarce, Sundeep Pillamari, Jnana Manoj Appikonda, Laura Diaz, Yanko Kranov, David McIlroy During recent years the need for high quality self-biased barium ferrite (BaFe$_{12}$O$_{19})$ thick films had been increasing due to its chemical stability, anisotropy and oriented hexagonal M-type ferrites. Our goal is to fabricate barium ferrite thick films to be incorporated in self-biased microwave devises. Different methods such as sputtering, pulse laser deposition, CVD and modified liquid phase deposition have been used for thick film deposition with limited or no success for thickness above 300$\mu $m. Excessive residual stresses of BaM films deposited with the previous methods and/or their low coercivity are the main problems targeted by this project. We present a low cost solution using BaFe$_{12}$O$_{19}$ nanopowder mixing with epoxy. The mix is placed on alumina substrates to fabricate 500$\mu $m thick films of BaM, resulting thick films with good magnetic properties such as a 4$\pi $Ms between 2.000 to 2.500 Gauss and a coercivity of 3800 to 4000 Oe. In addition, we have integrated the barium ferrite thick films into microwave devises and successfully deposited their contact lines for their testing and use. [Preview Abstract] |
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C1.00008: Energetic Neutral Atom Production due to Charge Exchange at Mars Erena Friedrich An energetic neutral atom (ENA) is formed in a charge exchange process where an energetic ion picks up an electron from a neutral particle. Mars, having no notable global intrinsic magnetic field, cannot shield the neutral particles in its atmosphere from the flow of energetic solar wind protons. Consequently, an extensive production of energetic hydrogen atoms (H-ENAs) occurs. In this study a 3D hybrid (kinetic ions, fluid electrons) quasi-neutral particle-in-cell (PIC) plasma simulation is being developed to investigate the production of H-ENAs due to collisions with atomic oxygen (O) and neutral nitrogen molecules (N$_{2})$ in the transition region of the Martian near-space environment. In order to better study the interaction between Mars' exosphere and ionosphere, multi-species reactions such as ionization by photons, electron recombination and charge exchange are self-consisitently included in the simulation model. The major ions included are exospheric solar wind protons and the planetary O$_{2}^{+}$, CO$_{2}^{+}$, O$^{+}$, and N$_{2}^{+ }$ions. The motion of the precipitating particles in the atmosphere is followed, and collisions with atmospheric ions and neutrals (O, CO$_{2}$, N$_{2})$ are governed by a Monte Carlo ``collision-by-collision'' algorithm. What is presented is a ``work in progress'' as we work towards our goal of computing the flux of escaping H-ENAs due to charge exchange with O and N$_{2}$. [Preview Abstract] |
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C1.00009: Hunting for Higgs at Fermilab D{\O}: Use of Multivariate Analysis Technique in Data Analysis Rakshya Khatiwada, Michael Pogwizd, Pushpa Bhat Theorized by Peter Higgs, the Higgs boson still awaits to be discovered. It is believed to ultimately complete the current standard model which excludes gravity. There has been ongoing research on Higgs boson in High Energy laboratories like Fermilab and CERN. Data is the limiting factor in today's context so an effective way of analyzing data is necessary. The primary goal of this research was to compare the Multivariate Data Analysis technique to the conventional method of data analysis using simulated Higgs boson data. Our results show that the Multivariate Analysis technique is an improvement over the conventional method of data analysis, accurately and efficiently separating data from the background signal. In the future, it has a potential to be a major tool of data analysis whether it be in the field of Physics or other areas of research. [Preview Abstract] |
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C1.00010: Liquid Argon Calorimetry for ATLAS Alan Robinson This summer, the largest collaborative physics project since the Manhattan project will go online. One of four experiments for the Large Hadron Collider at CERN in Geneva, ATLAS, employs over 2000 people. Canadians have helped design, construct, and calibrate the liquid argon calorimeters for ATLAS to capture the products of the high energy collisions produced by the LHC. From an undergraduate's perspective, explore how these calorimeters are made to handle their harsh requirement. From nearly a billion proton-proton collisions a second, physicists hope to discover the Higgs boson and other new fundamental particles. [Preview Abstract] |
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C1.00011: Optical Properties Measurements of Linear Alkylbenzene Charles Taylor Building on the success of the Sudbury Neutrino Observatory (SNO) experiment, the SNO+ collaboration is planning to replace the inner heavy-water volume with a liquid scintillator called linear alkylbenzene (LAB). Using the existing array of 9600 PMTs together with a lower energy threshold and higher light yield will allow SNO+ to probe new physics. Located in SNOLAB, currently the deepest underground lab in the world, SNO+ aims to have unique capabilities including detection of pep and CNO solar neutrinos. Complementing the solar neutrino programme, SNO+ will also offer competitive sensitivity on a relatively short time scale to neutrinoless double-beta decay with the addition of neodymium (Nd) to the target volume. The optical properties of LAB are currently under investigation. ISU has built a setup to measure the absorption over two meters, and also to measure the perpendicular scattering at intervals along the two-meter length. Geometry corrections will be made and the results will be compared to Monte Carlo simulations. [Preview Abstract] |
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C1.00012: ALPHA, Mass Generation and Quantum Information Shantilal Goradia The generation of Planck energy 10E19 Gev/Planck time during the observable age of the universe (10E60 Planck times) would generate 10E79 Gev. 10E79 Gev approximates the energy of the baryon number, implying an increase of the baryon number by 10E19/Planck time. What is the source of energy for this mass generation? The ALPHA implicated as negative entropy in [1] must create vacuum energy. Vacuum energy is negative energy. Nature must balance negative energy by generating positive energy (mass), implying ALPHA balances the increasing entropy of the visible universe and generates baryonic mass. Additionally, the successful cloning of the sheep Dolly, and observed molecular blinking dots in biochemistry support the binary BITS of ON and OFF states in [1]. Vindicating Hermite's 1873 mathematical linkage of the base of natural logarithm to transcendentality will implicate natural log based ALPHA in [1] as connected to consciousness. [1] Goradia S: www.arXiv.org/pdf/physics/0210040v3. [Preview Abstract] |
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C1.00013: Patterns in the Long Term Behavior of Eclipsing Binary Star System 44i-Bootis Caitlin Byrd-Fisher, Jeanine Fallen Bailey, Thomas Olsen Previously, we have assembled data on the binary star system 44i Bootis, collected by our group and others over nearly a century, concerning the timing of its primary eclipses. These have been previously modeled by an ephemeris equation, assuming a constant orbital period. We have previously shown that the system is slowing down a uniform rate. We present data demonstrating a small sinusoidal trend in the remaining differences between eclipse time observations and calculations (an O-C diagram). We sought to model the cause of this variation by the gravitational interaction of a planet orbiting the binary star pair. Such a planet would necessarily be a brown dwarf of 0.0475 solar masses, with a semi-major axis of 10.729 AU. We are examining the stability of such an orbit. We also present initial data for the binary star system VW Cephei. [Preview Abstract] |
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C1.00014: Characterization of CaMn$_{2}$O$_{4}$ By X-Ray Magnetic Linear Dichroism Johnathon Holroyd, Harshawardhan Bhatkar, Elke Arenholz, Ben White, John Neumeier, Yves Idzerda Perovskite manganite such as La$_{x}$Ca$_{(1-x)}$MnO$_{3}$ (LCMO) have recently drawn attention for their useful electronic and magnetic properties such as Colossal Magnetoresistance. It has been shown that under stress, LCMO thin films show changes in La and Ca concentrations near the interface. One potential impurity under La depleted conditions is antiferromagnetic CaMn$_{2}$O$_{4}$. In order to better understand the range of properties available within LCMO systems, it is important to be able to identify and characterize CaMn$_{2}$O$_{4}$ within LCMO thin films. X-ray absorption spectroscopy (XAS) and X-ray magnetic linear dichroism (XMLD) are well suited to this task due to their element specificity, sensitivity, and ability to characterize the measure the magnetic properties of antiferromagnetic systems. XAS and XMLD were measured on high quality single crystals of CaMn$_{2}$O$_{4}$. These spectra are distinguished from CaMnO$_{3}$ and demonstrate antiferromagnetic structure. [Preview Abstract] |
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C1.00015: Controlled Growth of Organic Semiconductor Films Using Liquid Crystal Solvents Kevin Bufkin, Brooks Ohlson, Ben Hillman, Brad Johnson, David Patrick Interest in using organic semiconductors in applications such as large area displays, photovoltaic devices, and RFID tags stems in part from their prospects for enabling significantly reduced manufacturing costs compared to traditional inorganic semiconductors. However many of the best performing prototype devices produced so far have involved expensive or time-consuming fabrication methods, such as the use of single crystals or thin films deposited under high vacuum conditions. We present a new approach for growing low molecular weight organic crystalline films at ambient conditions based on a vapor-liquid-solid growth mechanism using thermotropic nematic liquid crystal (LC) solvents. Tetracene is deposited via atmospheric-pressure sublimation onto substrates coated by a LC layer oriented using rubbed polyimide, producing films that are highly crystalline, with large grain sizes, and possessing macroscopic uniaxial orientation. This poster will describe the growth mechanism, discuss the effects of processing conditions such as LC layer thickness, substrate temperature and flux rate, and compare the results to a model of deposition-diffusion aggregation accounting for the finite thickness of the solvent layer. [Preview Abstract] |
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C1.00016: Synthesis and characterization of nanostructured cobalt-zinc ferrites Eric Montoya, Aaron Patz, Dan Shaw, Takele Seda \noindent Research in the area of nanomaterials has been increasing in the past few decades. Differing from their bulk phase counterparts, the properties of these nanomaterials are highly size dependent. Such materials promise to be of great importance: from high frequency applications to aided drug delivery to the study of quantum effects on the macro scale [quantum dots]. Synthesis of $\rm{Co}_{1-y}\rm{Zn}_y\rm{Fe}_2O_4$ nanoparticles was achieved through microemulsion techniques, where `y' ranges from 0 to 1 and was used to determine the relative concentration of Co and Zn cations in the spinel structure. XRD estimates that the particle size ranged from 10 to 20 nanometers. Vibrating SM and $^{57}$Fe M\"{o}ssbauer spectroscopy were used to study the magnetic and electronic properties of these nanomaterials. Our preliminary results suggest there are small but significant magnetic interactions between the particles. These interactions can be explained in terms of surface effects and in part the agglomeration of the particles. [Preview Abstract] |
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C1.00017: Chaotic Taylor Vortex Formation in Modified Taylor-Couette Flow in Systems of Varying Lengths Modeled by Reaction-Diffusion Equations Yunjie Zhao, Andrew Halmstad, Thomas Olsen, Richard Wiener Previously, we have observed a period-doubling cascade to chaos in Modified Taylor-Couette Flow with Hourglass Geometry\footnote{Richard J. Wiener \textit{et al}, Phys. Rev. E \textbf{55}, 5489 (1997).}. Such behavior has been modeled by The Reaction-Diffusion equation \footnote{H. Riecke and H.-G. Paap, Europhys. Lett. \textbf{14}, 1235 (1991).}. In the experiment, chaotic formation of Taylor-Vortex pair formation was restricted to a very narrow band about the waist of the hourglass. We examine the dependence of the range of locations in which vortex pair formation occurs. We compare to previous calculations and consider intermediate length systems as well. We find doubling the length to be sufficient to generate spatially chaotic behavior. [Preview Abstract] |
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C1.00018: Use of Multifractal Analysis to Characterize Chaotic Behavior of Laminar and Turbulent Regimes in Modified Taylor-Couette Flow Adam Kowalski, Yunjie Zhao, Thomas Olsen, Richard Wiener Previously we have presented basic fractal dimensional analyses\footnote{J. A. Glazier \& A. Libchaber, IEEE Trans. On Circuits and Systems \textbf{35-7}, 790 (1988).}$^,$\footnote{T. Halsey, M. H. Jensen, L. P. Kadanoff, I. Procaccia, \& B. I. Shraiman, Phys. Rev. A \textbf{33}, 1141 (1986).} of the irregular generation of new Taylor Vortex Pairs in Taylor-Couette flow with hourglass geometry\footnote{A. Kowalski, T. Olsen, \& R. Wiener, Bull. Am. Phys. Soc. \textbf{52-17}, 225 (2007).}. Our continued multifractal analysis of the system in both laminar and turbulent regimes allows us to now present more thorough insights into the physical system, and to further compare these two regimes. [Preview Abstract] |
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C1.00019: Conversion of an air conditioning unit to a heat pump Tim Vaughan, Don Schnitzler Energy usage and its environmental impact continue to be growing areas of concern globally. Space conditioning accounts for a large percentage of energy consumption annually as billions of dollars are used to heat and cool residence and commercial areas. Heat pumps are efficient space conditioners due to their ability to transfer existing heat instead of creating heat. Increased heat pump usage, especially when teamed with renewable energy sources, is a viable environmentally friendly option in the future. Interestingly, heat pumps function on the same basis as everyday refrigerators and air conditioners, yet unlike air conditioners, they have the ability to both heat and cool. In this project, an air conditioning unit has been successfully converted to a working air source heat pump. The project demonstrates the operation of a heat pump. The thermodynamics of heat pumps and methods for measuring heat pump efficiency are discussed. [Preview Abstract] |
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C1.00020: A physical model for microtubule polymerization Vahid Rezania, Jack A. Tuszynski In this work we propose a microscopic model to study the polymerization of microtubules (MTs). Starting from fundamental reactions during MT's assembly and disassembly processes, we systematically derive a nonlinear system of equations that determines the dynamics of microtubules in 3D. We found that the dynamics of a MT is mathematically expressed via a cubic-quintic nonlinear Schrodinger (NLS) equation. Interestingly, the generic 3D solution of the NLS equation exhibits linear growing and shortening in time as well as temporal fluctuations about a mean value which are qualitatively similar to the dynamic instability of MTs observed experimentally. By solving equations numerically, we have found spatio-temporal patterns consistent with experimental observations. [Preview Abstract] |
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C1.00021: Diffusion Tensor Imaging in Rat Spinal Cord In-Vivo Zeinab Al-Rekabi Diffusion Tensor Imaging (DTI), an MRI technique based on probing the structure of tissues at a microscopic level is used to determine regional values of Fractional Anisotropy (FA) and mean diffusivity (D$_{av})$ of excised and in-vivo rat spinal cords. Two pulse sequences: Spin Echo (SE) and Echo Planar Imaging (EPI) are optimized to provide the best image quality, signal-to-noise ratio (SNR) and the greatest spatial resolution at reasonable acquisition times in the rat spinal cord. The study was conducted using a 7T BRUKER BioSpec MRI animal scanner. In the ex-vivo experiments images with the spatial resolution of 100 $\mu $m and the SNR of 1.938 $\pm$ 0.010 were acquired in 2 minutes. After optimization both methods were applied in-vivo. The values of FA and D$_{av}$ acquired in this study showed good correlation with the literature values. Furthermore, results from these studies should provide the necessary baseline data for serial DTI in injured spinal cord in future studies. [Preview Abstract] |
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C1.00022: Superhydrophobic Behavior on Nano-structured Surfaces Daniel Schaeffer Superhydrophobic behavior is observed in natural occurrences and has been thoroughly studied over the past few years. Water repellant properties on uniform arrays of vertically aligned nano-cones were investigated to determine the highest achievable contact angle (a measure of water drop repellency), which is measured from the reference plane on which the water drop sits to the tangent line of the point at which the drop makes contact with the reference plane. At low aspect ratios (height vs. width of the nano-cones), surface tension pulls the water into the nano-cone array, resulting in a wetted surface. Higher aspect ratios reverse the effect of the surface tension, resulting in a larger contact angle that causes water drops to roll off the surface. Fiber drawing, bundling, and redrawing are used to produce the structured array glass composite surface. Triple-drawn fibers are fused together, annealed, and sliced into thin wafers. The surface of the composite glass is etched to form nano-cones through a differential etching process and then coated with a fluorinated self-assembled monolayer (SAM). Cone aspect ratios can be varied through changes in the chemistry and concentration of the etching acid solution. Superhydrophobic behavior occurs at contact angles $>$150\r{ } and it is predicted and measured that optimal behavior is achieved when the aspect ratio is 4:1, which displays contact angles $\ge $175\r{ }. [Preview Abstract] |
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C1.00023: T-matrix calculations of fractal black carbon atmospheric aerosol particle optical scattering Anna Smith, David Boness To better constrain global climate change computer models, and thereby to more fully understand the full extent of anthropogenic climate change, it is necessary to understand the physics of light scattering from those atmospheric aerosol particles that are caused by human activities. The IPCC AR4 report on the physical basis of climate change lists uncertainty in the effects of black carbon aerosol particles, caused by burning fossil fuels and organic matter, as one of the greatest uncertainties in current climate change understanding. This study hopes to increase the knowledge of how aerosols contribute to radiative forcing by using more realistic modeling of scattering properties. We use D. W. Mackowski's T- matrix code on fractal aggregates of uniform spherical monomers and compare this with fractal scattering predicted by the Raleigh-Debye-Gans approximation. The T-matrix code is checked for accuracy with one spherical particle as found with Mie theory. Scattering properties found using the T-matrix method are performed as a function of fractal dimension and number of monomers. Preliminary results will be presented. Future work will involve comparison with soot particle optical scattering measurements made at Seattle University. [Preview Abstract] |
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C1.00024: Electronic Realization Of Chaotic Systems Christopher Parker, Jeffrey Leiseth, Michael Braunstein, Sharon Rosell, Travis Petersen, Evan Masters, Eric Kangas The CWU chapter of the SPS is investigating electronic realizations of chaotic systems. Understanding the fundamental principles that govern this behavior is sought not only for its inherent educational value, but for its applications in physics, information theory, meteorology, biology and mathematics. J.C. Sprott has reported on a class of chaotic differential equations that can, in principle, be simply realized using discrete electronic components. These circuits can be used to investigate chaotic behavior in a simple system. We will present computational and experimental data collected from one simple chaotic circuit. Our computational results include eigenvalues and eigenvectors of the Jacobian, return maps, largest Lyapunov exponents and the numerical approximation of solutions to the differential equation utilized. Our data include output voltages at different points in the circuit representing the phase space behavior of the system. A comparison between the model and collected experimental data will be provided to analyze the realization of the nonlinear differential equation. [Preview Abstract] |
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C1.00025: Hyperspectral Image Compression Stephanie Wright, Dr. Agnieszka Miguel, Jason Ashbach Hyperspectral images gathered by satellites or aerial means provide a vast amount of data for geophysicists. A few applications include the exploration of minerals, research of land pollution, and military surveillance. NASA and other agencies are producing gigabytes of hyperspectral images which need to be transmitted and stored daily. As these images require high compression rates and preservation of data integrity, we are presented with an intriguing compression problem. In our research we investigate two compression algorithms: a near-lossless technique based on minimizing maximum absolute distortion (MAD) and a lossy based algorithm which minimizes mean squared error (MSE). Near-lossless algorithms provide high compression rates and a uniform distribution of error. Whereas MSE based algorithms yield high compression rates but a non-uniform distribution of error. Our goal is to determine which algorithm yields high compression rates and minimal data loss without modifying post processing of hyperspectral data. In order to compare these two compression algorithms and determine their effect on post processing we used ENVI's image processing tools. We classified the decompressed images for each algorithm and compared them to the classified original image. [Preview Abstract] |
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C1.00026: The Use of Inquiry Based Learning in Electricity and Magnetism Laboratories: Having Students Explore Charging by Induction. Steven Kreft, Andrew Boudreaux Traditionally, university physics is taught in a lecture dominated style in which students are expected to passively absorb ideas that are presented in class. During the laboratory component, students often verify formulas given to them and expect that instructors will provide answers to their questions. In the Physics Department at Western Washington University we have implemented inquiry based labs in our calculus based introductory course. In these labs, instructors do not give students answers, but use guiding questions to help students develop their own understanding. In this poster, we present an example of an inquiry activity in which students use previously learned concepts of charge, conductors, polarization and grounding to build their own understanding of charging by induction. The goal is to promote not only conceptual understanding, but also student abilities to engage in multiple step reasoning involving more then one concept. After giving a brief synopsis of the activity, some data will be presented as a preliminary assessment of the effect of inquiry instruction on student learning. [Preview Abstract] |
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C1.00027: The Influence of Segmental Impedance Analysis in Predicting Validity of Consumer Grade Bioelectrical Impedance Analysis Devices Andy Sharp, Jennifer Heath, Janet Peterson Consumer grade bioelectric impedance analysis (BIA) instruments measure the body's impedance at 50 kHz, and yield a quick estimate of percent body fat. The frequency dependence of the impedance gives more information about the current pathway and the response of different tissues. This study explores the impedance response of human tissue at a range of frequencies from 0.2 - 102 kHz using a four probe method and probe locations standard for segmental BIA research of the arm. The data at 50 kHz, for a 21 year old healthy Caucasian male (resistance of 180$\Omega \quad \pm $10 and reactance of 33$\Omega \quad \pm $2) is in agreement with previously reported values [1]. The frequency dependence is not consistent with simple circuit models commonly used in evaluating BIA data, and repeatability of measurements is problematic. This research will contribute to a better understanding of the inherent difficulties in estimating body fat using consumer grade BIA devices. \newline [1] Chumlea, William C., Richard N. Baumgartner, and Alex F. Roche. ``Specific resistivity used to estimate fat-free mass from segmental body measures of bioelectrical impedance.'' \underline {Am J Clin Nutr} 48 (1998): 7-15. [Preview Abstract] |
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C1.00028: Theoretical Multiblock Coarse-graining Approach for Homopolymer Melts Trevor Keiber A microscopic theory for coarse-graining homopolymer melts as an ensemble of connected soft-colloidal particles (blocks) has been developed, which effectively maps a polymer with many monomers to a chain of soft-core bound particles. The Ornstein-Zernike liquid-state integral equation was solved to provide a mesoscopic description of the system at the level of the block centers of mass. Analytical expressions for the intramolecular and intermolecular correlation functions were derived for an arbitrary number of blocks. The block-block correlation functions were used to derive the necessary intermolecular and intramolecular coarse-grained potentials for mesoscale computer simulations. [Preview Abstract] |
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