Bulletin of the American Physical Society
Spring 2010 Meeting of the Ohio Section of the APS
Volume 55, Number 4
Friday–Saturday, April 30–May 1 2010; Flint, Michigan
Session P1: Poster Session (4:00-6:00PM) |
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Room: Campus Center Fifth Floor |
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P1.00001: Metamodel based optimization of material parameters in a finite element simulation of tensile tests Justin Brown, Cavendish McKay We determine the optimum set of parameters for simulating a tensile test of a sample of Zytel\textregistered \ nylon resin in a finite element model. Using manufacturer supplied data and initial tensile measurements as starting data, we use a metamodel based optimization scheme to iteratively improve the choice of parameters. The commercial finite element solver {\sc LS-DYNA} and optimization package LS-Opt are used to assess the quality of the material parameter choice. A map of the response surface is presented to illustrate some challenges with the metamodel based approach. [Preview Abstract] |
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P1.00002: Stability and convergence of a finite element simulation of a tensile test Ezekiel Hadley, Cavendish McKay We study the effects of element formulation, size, and resolution on the rate of convergence and computational cost of a finite element simulation of a tensile test involving thin strips of plastic resin. We find that tetrahedral elements outperform hexahedral elements both in terms of rate of convergence as well as computational cost, even though the overall element count is higher in the tetrahedral mesh. Resolution requirements for convergence are significantly different in the directions parallel to and across the applied tension. Simulations using the commercial finite element solver {\sc LS-DYNA} show both convergence and performance results to be consistent across four different material definitions, and over a large range of material parameters. Some discussion of instabilities associated with the extreme aspect ratio of our test samples will also be included. [Preview Abstract] |
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P1.00003: Solar Cells for High Temperature Environments in Space Geoffrey Landis Future NASA missions into regions close to the sun will require power systems to operate in high temperature, high light-intensity environments. Some of the missions are: \begin{itemize} \item Solar Probe Plus \item Mercury probes \item Venus probes \end{itemize} Approaches to solar array design include developing improved high-temperature solar cells, reducing incident intensity to limit temperature, and use of cooling to minimize the temperature. Each of these missions has different challenges. Solar Probe Plus, a mission to the outer corona of the sun, will operate from 1 AU inward to 9.5 solar radii from the sun, nearly three orders of magnitude in incident intensity. Probes to the surface of Mercury experience a solar intensity of 10 kW/m$^{2}$ with temperature ranging from 425$^{\circ}$C at noon to -175$^{\circ}$C at night; while Mercury orbital missions are subject to incident solar radiation, reflected sunlight, and thermal IR radiated from the planet's surface. Venus presents the greatest challenge to photovoltaic operation, with surface temperature of 450$^{\circ}$C, low intensity sunlight, and a corrosive environment. [Preview Abstract] |
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P1.00004: Polymer Electrolyte Membrane Fuel Cell with Vertically Aligned Carbon Nanotube Electrode Ann Call, Gabriel Goenaga, Junbing Yang, Di-Jia Liu Carbon nanotubes (CNTs) have been considered a promising material for various applications, including polymer electrolyte membrane fuel cells (PEMFCs). There have been a number of reports on CNT based membrane electrode assembly (MEA) in PEMFC, but CNTs in these electrodes are oriented randomly and the advantages associated with the structural properties of CNTs were not fully utilized. We report here our evaluation of MEA made of catalyst decorated, vertically aligned carbon nanotube (ACNT) layers. For comparison, a commercial MEA prepared through conventional ink-based process was tested under similar conditions. Improved performance was observed for ACNT-based MEA, particularly at high current region, suggesting enhancement in mass transport and improved water management. [Preview Abstract] |
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P1.00005: Investigating the Intracluster Dynamics of h and chi Persei Chad Byers, Ann Bragg The two young open clusters h and chi Persei are in close proximity to each other and are of roughly the same age. While h and chi Persei are extremely similar, high mass stars are more centrally concentrated in h Persei than in chi Persei. This difference raises questions about the dynamical timescales of and primordial conditions within the clusters. Radial velocity measurements would help distinguish which of these two effects is most likely responsible for the observed mass segregation. This poster presentation will demonstrate the need for such observations, characterize the needed observations, and outline preparations currently underway to obtain the observations. [Preview Abstract] |
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P1.00006: The black hole and gas disk in NGC 4552 Peter Kircher, Jason Pinkney We present kinematics and photometry of the Elliptical galaxy NGC 4552. This is part of a program to directly measure the masses of supermassive black holes in galaxies. Our photometry is derived from V and I band CCD images from the ground and from the Hubble Space Telescope (HST). We find that fitting the 2D surface brightness distribution with parametric Sersic models does not match the light profile as well as standard ellipse fitting. The combined (HST+ground) light profile is used to find the enclosed mass profile of the galaxy. The stellar line of sight velocity distribution is measured from CaII absorption lines at 8498, 8542, and 8662 {\AA} in ground-based long-slit spectroscopy. The stellar velocity dispersion is about 300 km/s, which predicts a black hole mass of about $7\times10^8 M_{Sun}$. Our HST spectra of the H$\alpha$-emitting ionized gas shows ordered motion and hints of a Keplerian rotation curve. We model the system as a thin, inclined disk of gas rotating in the galaxy + black hole potential. The measured gas kinematics are best reproduced by models which include a large, central black hole mass. [Preview Abstract] |
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P1.00007: Induction heating and controlled drug release from thermosensitive magnetic microgels R. Regmi, S.R. Bhattarai, C. Sudakar, A.S. Wani, R. Cunninghum, P.P. Vaishnava, R. Naik, D. Oupicky, G. Lawes Poly-N-isopropyl acrylamide (PNIPAM) is a biocompatible thermosensitive polymer that exhibits reversible volume phase transition from a hydrophilic coil to hydrophobic globule at the lower critical solution temperature (LCST) of 32 $^{\circ}$C. To stimulate conformational change we introduced magnetite nanoparticles (size $\sim $12 nm) in the PNIPAM matrix. The PNIPAM/magnetite nanoparticles composite was then exposed to an alternating magnetic field at a frequency of 380 kHz to induce heating in the nanoparticles by Neel and Brownian relaxations. We report \textit{in vitro} controlled release of anti-cancer drug mitoxantrone which was loaded into PNIPAM/magnetite nanoparticles composite, driven solely by the heating induced by the external magnetic field. We found that the drug released reached 4{\%} in only 4 minutes of heating to 50 $^{\circ}$C. We also present results on dielectric and magnetic anomalies near the LCST of the PNIPAM-Fe$_{3}$O$_{4}$ composite. [Preview Abstract] |
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P1.00008: Detection of benign epithelia, prostatic intraepithelial neoplasia, and cancer regions in radical prostatectomy tissues using Raman spectroscopy Suneetha Devpura, Jagdish S. Thakur, Ratna Naik, Fazlul H. Sarkar, Wael A. Sakr, Vaman M. Naik In this study we have investigated Benign Epithelia (BE), Prostatic Intraepithelial Neoplasia (PIN), adenocarcinoma, and different Gleason scores in human prostate bulk tissues using Raman spectroscopy. A careful investigation of the data shows that two main differences in the Raman spectral features of BE, PIN, and cancerous tissues: ($i)$ a strong variations in the band intensities of certain bands, (\textit{ii}) shift in certain band positions. In order to quantify these variations, Raman data were further analyzed using chemometric methods of Principal Component Analysis (PCA) and Discriminant Function Analysis (DFA). The PCA and DFA clearly separated the data into three main distinct pathological groups representing BE, PIN, and cancerous state in tissue. Similarly the analysis of the Raman data of tissues with different Gleason scores shows that the data can be categorized into three distinct groups representing Gleason scores 6, 7, and 8. The results of this study demonstrate that Raman spectroscopy can diagnose different stages of the prostate cancer. [Preview Abstract] |
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P1.00009: Raman spectral analysis of wet-spun films of CaDNA with varying amounts of CaCl$_{2}$ as a function of relative humidity M. Schwenker Smith, Scott Lee, Allan Rupprecht Raman spectroscopy has been used to probe the amount of DNA in the B conformation in wet-spun films of CaDNA which contain varying amounts of CaCl$_{2}$ as a function of relative humidity. This determination is made by measuring the relative intensity of the B-form marker band at about 834 cm$^{-1}$. Our experiments show that CaDNA is in the B conformation from 98{\%} relative humidity (rh) down to 75{\%} and is disordered at lower humidities. Interestingly, a maximum in the relative amount of B-DNA is observed near 80{\%} rh. [Preview Abstract] |
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P1.00010: Modifying phase transitions and spin structure of Ni$_{3}$V$_{2}$O$_{8}$ through transition metal doping Akila Kumarasiri, Parashu Kharel, Ambesh Dixit, Gavin Lawes Ni$_{3}$V$_{2}$O$_{8}$ is a Kagome staircase material which has attracted considerable interest in recent years as it provides an excellent platform for studying the spin structure in geometrically frustrated materials. We have studied the effects of transition metal doping on the magnetic phase transitions of powder Ni$_{3}$V$_{2}$O$_{8}$ through dielectric, heat capacity and AC susceptibility measurements. (Ni$_{1-x}$M$_{x})_{3}$V$_{2}$O$_{8}$ (M = Zn, Cu and Co) powder samples were prepared using a standard metal-organic solution synthesis. We have mainly focused on the two phase transitions at T$_{H}$ = 9.2 K and T$_{L}$ = 6.3 K in undoped Ni$_{3}$V$_{2}$O$_{8}$. On doping with non magnetic Zn, the system acts similar to spin dilution where the transition temperature is suppressed linearly with the Zn fraction. However, spin 1/2 Cu and spin 3/2 Co doping shows significant deviation from simple site dilution. The Co:Ni$_{3}$V$_{2}$O$_{8}$ system has a crossover at moderate Co fraction where the system changes into a Co$_{3}$V$_{2}$O$_{8}$ type spin structure. Cu doping completely suppresses at least one phase transition at a relatively low Cu fraction. We also find that the Ni$_{3}$V$_{2}$O$_{8}$ spin structure is fairly robust and remains largely unaffected by introducing a few percent of a dopant, unlike the Co$_{3}$V$_{2}$O$_{8}$ spin structure, which is very sensitive to doping. [Preview Abstract] |
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P1.00011: Continuum Elasticity Modeling and Nonlinear Effects during Epitaxially Strained Island Evolution Champika Gigiriwala Gamage, Zhi-Feng Huang The formation of surface nanostructures such as islands or quantum dots during strained film epitaxy has attracted continuing great interest. One of the underlying mechanisms has been attributed to the occurrence of morphological instability of the strained film, for which the coupling between film/substrate misfit strains, film deposition rate and growth temperature plays a major role. In this research we focus on the nonlinear evolution of strained surface nanostructures during epitaxy, via constructing a continuum elasticity model based on the 2nd order perturbation theory. The resulting nonlinear evolution equation for film morphology, which also incorporates some realistic factors such as wetting effects, yields a long-wavelength, dynamic description of surface islands or quantum dots. The morphological properties of the growing film and the self-organization process of the coherent surface islands are examined, with the dependence on various material parameters and growth conditions identified. [Preview Abstract] |
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P1.00012: A dusty plasma 1-ring to rule them all T.E. Sheridan, James C. Gallagher One-dimensional and quasi-one-dimensional strongly-coupled dusty plasma rings have been created experimentally in the DONUT (Dusty ONU experimenT) apparatus. Longitudinal (acoustic) and transverse (optical) dispersion relations for the 1-ring were measured and found to be in very good agreement with the theory for an unbounded straight chain of particles interacting through a Yukawa (i.e., screened Coulomb or Debye-H\"uckel) potential. These rings provide a new system in which to study one-dimensional and quasi-one-dimensional physics. [Preview Abstract] |
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P1.00013: Investigation of acoustic pulses in one-dimensional dusty plasma James C. Gallagher, T.E. Sheridan We have studied the excitation and propagation of acoustic pulses in a one-dimensional dusty plasma with $n=65$ particles and a lattice constant $a=1.12 \pm 0.07$ mm. Pulses were launched by applying a 100-mW laser pulse to one end of the chain for laser pulse durations from 0.10 to 2.0 s. We observe large-amplitude damped acoustic waves that propagate for a significant distance. The measured acoustic speed is $c = 15.5 \pm 0.2$ mm/s independent of the laser pulse duration, indicating that the pulse propagation is wave-like rather than solitonic. [Preview Abstract] |
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P1.00014: Positron Lifetime Spectroscopy Jacob Martin, Herbert Jaeger We have assembled a positron lifetime spectrometer using two scintillation detectors in a slow-fast coincidence configuration. The decay of $^{22}$Na serves as a convenient source of positrons. Positron energies are sufficiently high that positrons penetrate into the bulk of the surrounding material under study. A 1275 keV gamma ray emitted less than 10 ps following the positron decay serves as the lifetime start signal, while the detection of a 511 keV annihilation gamma signals the end of life of the positron. The first version of our spectrometer employs NaI scintillators that have good detection efficiencies but with time resolution of several nanoseconds are not particularly suitable for measuring sub-nanosecond lifetimes of positrons in metals. Recently we have replaced the NaI detectors with ones employing plastic scintillators, which offer a time resolution of better than 1 ns. First results of measurements performed with this apparatus will be discussed. [Preview Abstract] |
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P1.00015: Investigation of the Quenching Mechanism of a Fluorescence Process Yi Wang, Debra Egolf, Dennis Kuhl The properties and behavior of an electronic excited state were investigated experimentally. The goal was to determine whether, upon interaction with a series of molecules Q, (i.e., 1,2,4-trimethoxybenzene, 1,4-dimethoxybenzene, naphthalene), the fluorescent states of 9,10-dicyanoanthracene and 9-cyanoanthracene are quenched via an electron transfer process. A Stern-Volmer investigation enables evaluation of the rate constant, k$_{q}$, for quenching of the cyanoanthracene excited state. Then a Rehm-Weller plot of k$_{q}$ vs. Gibbs energy of electron transfer, $\Delta $G$_{et}$, allows determination of the Gibbs energy of activation, $\Delta $G$_{et}^{\cdot}$, and the rate constant, k$_{et}$, for the electron transfer process. UV-visible and fluorescence spectroscopy, cyclic voltammetry, laser-based kinetic analyses, and computer modeling were used in this investigation. Now that the electron transfer process previously reported for these chemical systems has been validated using our methods, future investigations will involve manipulation of various experimental parameters (i.e., anthracene sustituents, solvent polarity, etc.). [Preview Abstract] |
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P1.00016: Dielectric properties of TiO$_{2}$ and Zr-doped TiO$_{2}$ thin films Chandra Thapa, Sudakar Chandran, Sahana M.B., Vaman Naik, Karur Padmanabhan, Ratna Naik The leakage current and photocatalytic performance of TiO$_{2}$ can be improved by properly doping Ti with other transition metal cations. For example, Zr$^{4+}$ doping for Ti$^{4+}$ can significantly improve the desired properties. We have studied the properties of pure TiO$_{2}$ and Zr-doped TiO$_{2}$ thin films prepared by MOD technique and annealed from 650 to 950$^{\circ}$C. Both XRD and Raman spectra show TiO$_{2}$ to be mostly in anatase form below the annealing temperature of 850$^{\circ}$C and in rutile phase above 850$^{\circ}$C. However, the Zr doping does not lead to rutile phase formation. We have studied I-V characteristics and frequency dependence of dielectric constants of pure and Zr-doped TiO$_{2}$ in the frequency range of 100Hz--1MHz. We find an improvement in leakage current with increasing annealing temperature from 650 to 950$^{\circ}$C for both TiO$_{2}$ and Zr-doped TiO$_{2}$, but no appreciable improvement in the leakage current upon Zr doping. The dielectric constant of pure TiO$_{2}$ films improves from 30 to 80 with increasing annealing temperature, whereas that of Zr-doped TiO$_{2}$ is independent of annealing temperature and its value is $\sim$50 at 30 kHz. This may be attributed to the persistence of anatase phase of TiO$_{2}$ over wide range of annealing temperatures for Zr-doping. These properties and their implications for different applications will be discussed. [Preview Abstract] |
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P1.00017: Calculation of Positron Binding Energies and Implications for Feshbach-Resonant Positron-Uracil Annihilation Indika Wanniarachchi, Caroline Morgan Here we investigate by first-principles calculations the possible role of vibrational Feshbach resonances in enhancing positron annihilation for low-energy positron beams incident on uracil, a base found in RNA. Geometries, vibrational polarizabilities, and dipole moments for uracil and 5-halouracils are calculated with density functional theory, DFT-B3LYP with a 6-31G+(d, p) basis set, and are used to determine positron-uracil and positron-5-halouracil binding energies. The energy of the Feshbach resonances is then determined by the law of energy conservation. Experimental work on positron interactions with uracil and 5-halouracils in conjunction with the theoretical work reported here is underway. [Preview Abstract] |
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P1.00018: Space Inside a Liquid Sphere Transforms into De Sitter Space by Hilbert Radius Dmitri Rabounski, Larissa Borissova Consider space inside a sphere of incompressible liquid, and space surrounding a mass-point. Metrics of the spaces were deduced in 1916 by Karl Schwarzschild. 1) Our calculation shows that a liquid sphere can be in the state of gravitational collapse (g$_{00}$~=~0) only if its mass and radius are close to those of the Universe (M~=~8.7$\times $10$^{55}$~g, a~=~1.3$\times $10$^{28}$~cm). However if the same mass is presented as a mass-point, the radius of collapse r$_{g}$ (Hilbert radius) is many orders lesser: g$_{00}$~=~0 realizes in a mass-point's space by other conditions. 2)~We considered a liquid sphere whose radius meets, formally, the Hilbert radius of a mass-point bearing the same mass: a~=~r$_{g}$, however the liquid sphere is not a collapser (see above). We show that in this case the metric of the liquid sphere's internal space can be represented as de Sitter's space metric, wherein $\lambda $~=~3/a$^{2}$~$>$~0: physical vacuum (due to the $\lambda $-term) is the same as the field of an ideal liquid where $\rho _{0}$~$<$~0 and p~=~-$\rho _{0 }$c$^{2}$~$>$~0 (the mirror world liquid). The gravitational redshift inside the sphere is produced by the non-Newtonian force of repulsion (which is due to the $\lambda $-term, $\lambda $~=~3/a$^{2}$~$>$~0); it is also calculated. [Preview Abstract] |
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P1.00019: Investigating the effective hydrodynamic size of dextran coated iron oxide nanoparticles Prem Vaishnava, Vikas Gumber, Rajesh Regmi, Correy Black, Ambesh Dixit, Vaman Naik, Chandran Sudakar, Ratna Naik, Gavin Lawes We report synthesis and functionalization of magnetite nanoparticles by coating with dextran having 5, 15-20, 60-90, and 670 kDa molecular weights. The hydrodynamic radii of the functionalized nanoparticles suspended in water measured by dynamic light scattering technique assuming the bulk value for viscosity, were 91, 100, 106, and 132 nm, respectively. By measuring the ac magnetic loss, we determined the effective sizes to be 105, 113, 122, and 136 nm, respectively. The sizes measured by these techniques are approximately twice as large as expected given the iron oxide nanoparticle size and surfactant molecular chain length, at least for the lower molecular weight dextran. Comparing the results of hydrodynamic sizes studies, we conclude that the effective viscosity for the coated nanoparticles may be different than the bulk viscosity of the carrier liquid. [Preview Abstract] |
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P1.00020: Production and Electrical Characterization of Graphene Nanoribbons from Pristine Graphite in Solution Cheng Ling, Gabriel Setzler, Jin Jin, Seungsoo Kim, Hyeun Joong Yoon, Mark Ming-Cheng Cheng, Zhixian Zhou We have produced graphene nanoribbons by sonicating pristine graphite in solution. Atomic force microscopy (AFM) was used to characterize individual graphene Nanoribbons deposited onto Si/SiO2 substrates. Monolayer and few layer graphene nanoribbons were observed. Field effect transistor devices of individual nanoribbons were fabricated, and their electrical transport properties were measured. Possible mechanisms of graphene nanoribbon formation and electrical transport data on graphene nanoribbon devices will be discussed. [Preview Abstract] |
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P1.00021: The Electron Affinity of Indium and the Fine Structure of In$^{-}$ Measured using Infrared Photodetachment Threshold Spectroscopy C.W. Walter, Y. Li, D.J. Matyas, D.J. Carman, N.D. Gibson The binding energies of the fine structure levels of the indium negative ion (In$^{-})$ have been measured using infrared photodetachment threshold spectroscopy. The relative cross section for neutral atom production was measured with a crossed ion-beam-laser-beam apparatus over selected photon energy ranges between 300 -- 670 meV. An $s$-wave threshold was observed due to the opening of the In$^{-}$ (5$p^{2} \quad ^{3}P_{0})$ to In (5$p$ $^{2}P_{1/2})$ ground-state to ground-state transition, yielding an accurate value for the electron affinity of In. Thresholds were also observed for detachment from the J=1 and J=2 excited fine structure levels of In$^{-}$, permitting accurate determination of the fine structure splittings of the negative ion. [Preview Abstract] |
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P1.00022: The Spread and Absorption of Chemicals on Military Relevant Materials Sara Ketterer, Debra Pratt, Homayun Navaz, Michael Herman, Yuri Sikorski, Ali Zand The spread of chemicals in the environment poses great danger to natural ecosystems. The rate and the diameter of chemical spread on various surfaces were measured. These spread properties were correlated to the surface roughness as well as viscosity and surface tension of liquid chemical. Surface Imagery was obtained using optical and traditional profilometers. The roughness measurements were used along with rate of spread to develop a mathematical model. ESEM (Environmental scanning electron microscope) was utilized to understand how the chemicals adsorb to the surface of the paints. This investigation seeks to determine how surface and chemical properties affect the spread. The results of our investigation will be presented. [Preview Abstract] |
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P1.00023: Experimental Investigation of Light Induced Atomic Desorption Timothy Uher, Paul Voytas, Elizabeth George We are investigating the phenomenon of light induced atomic desorption (LIAD). In this effect, alkali atoms which are adsorbed onto nanoporous coatings can be ejected, or desorbed, by the shining of non-coherent light. In our setup, we use a glass cell that is coated with polydimethylsiloxane (PDMS) and filled with Rubidium vapor. As atoms get desorbed from the coating, the vapor density will increase. We can quantify the magnitude of the effect by monitoring the vapor density. This is done by measuring the transmission through the cell of a diode laser beam on resonance with a Rb spectral line. We are able to determine ratios of the vapor density with the desorbing lamp on and off and measure time scales to reach equilibria. The laser is able to be locked onto resonance of a spectral line of either the $^{87}$Rb or $^{85}$Rb isotopes. From this, we can mathematically model the effect and find how the effect depends on desorbing light intensity, temperature, and vapor densities of the different isotopes. Current results will be presented. [Preview Abstract] |
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P1.00024: Dinosaur dynamics in the Jurassic Era Scott Lee Dinosaurs were fascinating animals and elicit much excitement in the classroom. Analysis of fossilized dinosaur trackways permits one to estimate the locomotion speeds and accelerations of these extinct beasts. Such analysis allows one to apply Newton's laws of motion to examples from the Jurassic Era. [Preview Abstract] |
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P1.00025: Python Graphical User Interface (GUI) for Control of the Levitated Dipole Experiment David Jacome, Darren Garnier, Paul Woskov, Jay Kesner The Levitated Dipole Experiment (LDX) is used to study the confinement properties of plasmas in a magnetic dipole field. In LDX a superconducting coil is levitated for up to 3 hours within a large vacuum chamber to produce the confining dipole field. The plasma experiments take place during this time, with $\sim$10 second plasma shots, one shot every $\sim$5 min. MDSplus software is used to run the experiment and store the data. The software is currently controlled by command line operations. Since levitation time is limited, it's important to maximize efficiency and accuracy of experimental operations. Here, we present a Graphical User Interface (GUI) to efficiently control the operation of the experiment. The need for a GUI that integrates the MDSplus data cycle, cell access control, and routine experimental parameter controls is necessary. The GUI program provides a simple method for monitoring and setting experiment parameters. Python is used as the primary language to run the commands. A program called XRCed distributed by wxPython works as a visual tool. [Preview Abstract] |
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P1.00026: Preliminary investigation of single-file diffusion in complex plasma rings W.L. Theisen, T.E. Sheridan Particles in one-dimensional (1D) systems cannot pass each other. However, it is still possible to define a diffusion process where the mean-squared displacement (msd) of an ensemble of particles in a 1D chain increases with time $t$. This process is called single-file diffusion. In contrast to diffusive processes that follow Fick's law, ${\rm msd}\propto t$, single-file diffusion is sub-Fickean and the msd is predicted to increase as $t^{1/2}$. We have recently created 1D dusty (complex) plasma rings in the DONUT (Dusty ONU experimenT) apparatus. Particle position data from these rings will be analyzed to determine the scaling of the msd with time and results will be compared with predictions of single-file diffusion theory. [Preview Abstract] |
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P1.00027: Room temperature ferromagnetism and spin polarization in Cr doped InN thin films Ambesh Dixit, C. Sudakar, P. Thapa, R. Panguluri, V. Naik, R. Naik, J.S. Thakur, B. Nadgorny, G. Lawes Understanding the development of ferromagnetism in transition metal doped semiconductors is a topic of great current interest. We studied the properties of chromium doped InN thin films fabricated by RF sputtering (In$_{1-x}$Cr$_{x}$N, where x= 0, 0.02 and 0.05) on c-sapphire substrates as a possible dilute magnetic semiconductor. We carried out detailed structural, optical, electrical, and magnetic characterization of these samples to investigate the interplay of these different materials properties. These films are found to be polycrystalline without any secondary impurity phases. Optical and electrical measurements indicate that these films are highly degenerate and have a carrier concentration of $\sim $ 10$^{20}$ cm$^{-3}$. Most significantly, we find that these films show room temperature ferromagnetism. We present evidence for intrinsic magnetic properties through measurements of the spin polarization. The results are discussed in the context of carrier mediated ferromagnetism. [Preview Abstract] |
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P1.00028: \textit{In vivo} decomposition study of coated magnesium alloys Desiree White, Tyler Piersma, David LeCronier, Xingguo Cheng, Montserrat Rabago-Smith In the last decade, magnesium has resurged as an important biomaterial. Its mechanical properties are very similar to natural bone, and it degrades in vivo to non toxic substances. Unfortunately, corrosion of pure magnesium \textit{in vivo} is rapid, thus coated alloys that decrease its corrosion could be used as implants in orthopedics. This presentation will describe the degradation results in cell cultures and in rats. [Preview Abstract] |
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P1.00029: \textit{In vitro} decomposition study of coated magnesium alloys Tyler Piersma, Desiree White, Xinggou Cheng, Montserrat Rabago-Smith, David LeCronier In the last decade, magnesium has resurged as an important biomaterial. It's mechanical properties are very similar to natural bone, and it degrades in vivo to non toxic substances. Unfortunately, corrosion of pure magnesium \textit{in vivo} is rapid, thus coated alloys that decrease it's corrosion could be used as implants in orthopedics. This presentation will describe the degradation results in a simulated body fluid (SBF). [Preview Abstract] |
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P1.00030: Digital Receptor Image Quality Evaluation:~Effect of Different Filtration Schemes Simon Murphy, Olav Christianson, Maxwell Amurao, Ehsan Samei The International Electrotechnical Commission provides a standard measurement methodology to provide performance intercomparison between imaging systems. Its formalism specifies beam quality based on half value layer attained by target kVp and additional Al filtration. Similar beam quality may be attained more conveniently using a filtration combination of Cu and Al. This study aimed to compare the two filtration schemes by their effects on image quality in terms of signal-difference-to-noise ratio, spatial resolution, exposure index, noise power spectrum, modulation transfer function, and detective quantum efficiency. A comparative assessment of the images was performed by analyzing commercially available image quality assessment phantom and by following the IEC 62220-3 formalism. [Preview Abstract] |
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P1.00031: Haunted Quantum Entanglement: Two Scenarios Douglas Snyder Two haunted quantum entanglement scenarios are proposed that are very close to the haunted measurement scenario in that: 1) the entity that is developing as a which-way marker is effectively restored to its state prior to its being fixed as a w-w marker, and 2) the entity for which the developing w-w marker provides information is restored to its state before it interacted with the entity which subsequent to the interaction begins developing as a w-w marker. In the hqe scenarios, the loss of developing w-w information through 1 relies on the loss of a developing entanglement. In scenario 1, the photon initially emitted in one of two micromaser cavities and developing into a w-w marker is effectively lost through the injection of classical microwave radiation into both of the microwave cavities after the atom initially emits the photon into one of the micromaser cavities, exits the cavity system, and before this atom reaches the 2 slit screen. The atom is restored in both of the two new scenarios to its original state before it emitted a photon by an rf coil situated at the exit of the micromaser cavity system. In scenario 2, the cavity system and everything from the atom source forward to the cavity system is enclosed in an evacuated box. After the atom that emits the photon exits the cavity system and before it reaches the 2 slit screen, the cavity system opens (and the photon escapes in the evacuated box) and then the box is opened and the photon escapes into the environment. [Preview Abstract] |
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P1.00032: Digital Simulation of Thunder from Three-Dimensional Lightning James Dunkin, Daniel Fleisch The physics of lightning and its resultant thunder have been investigated by many people, but we still don't have a full understanding of the governing processes. In this study, we have constructed a three-dimensional model of lightning using MATLAB$^{\mbox{{\textregistered}}}$ software, and used N-waves as postulated by Ribner and Roy to synthesize the resultant thunder signature. In addition, we have taken an FFT of the thunder signature, and compared the time-domain waveform and frequency spectrum to recordings of thunder taken over the summer of 2009. This analysis is done with the goal of further understanding the processes of thunder production. [Preview Abstract] |
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