Bulletin of the American Physical Society
Annual Meeting of the Four Corners Section of the APS
Volume 58, Number 12
Friday–Saturday, October 18–19, 2013; Denver, Colorado
Session G1: Poster Session (6:00 - 7:30 pm) |
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Chair: Shane Larson, Northwestern Unversity Room: 3rd Floor Foyer |
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G1.00001: Spatailly Resolved Fluorescence Correlation Spectroscopy for Monitoring Biomolecular Dynamics Farshad Abdollah-Nia, Kevin Whitcomb, Martin Gelfand, Alan van Orden Two-beam Fluorescence Correlation Spectroscopy has been used to examine the diffusion, flow, and reaction rates of various ions and biological molecules, such as DNA, RNA, and proteins. Two laser beams were focused to form femtoliter probe regions in a capillary through which the analyte solution flowed continuously under the influence of an applied electric field or mechanical pressure. This poster introduces the theoretical and experimental concepts behind this technique, and presents some example results obtained by this group. [Preview Abstract] |
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G1.00002: Collective Excitations in Quasi-2D Condensates Andrew Barentine, Dan Lobser, Heather Lewandowski, Eric Cornell Quantum gases confined to lower dimensions exhibit remarkable physical properties such as the Berezkinskii-Kosterlitz-Thouless transition or the Tonks-Girardeau gas. Confinement effects in a quasi-2D condensate are predicted to shift the frequency of certain collective excitations, in particular the monopole mode. In our experiment, quasi-2D condensates are created by loading a 3D condensate into a 1D optical lattice, collective modes are then parametrically driven by modulating the strength of the trap. We have characterized a potential source of systematic error associated with a cross dimensional anharmonicity in the trap. This so called ``anharmonic shear'' also allows us to separate and simultaneously image each individual layer in the lattice. [Preview Abstract] |
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G1.00003: The behavior of Neutral Densities between 45 and 90 km Determined from Rayleigh Lidar Observations above Logan, Utah David Barton, Vincent Wickwar, Leda Sox, Joshua Herron A Rayleigh-scatter lidar operated at the Atmospheric Lidar Observatory (ALO; 41.7$^{\circ}$ N, 111.8$^{\circ}$ W), part of CASS on the campus of Utah State University (USU), and collected extensive data between 1993 and 2004. From the Rayleigh lidar photon-count returns relative densities throughout the mesosphere, from 45 to 90 km, were determined. Using these relative densities three density climatologies were derived, each using a different density normalization at 45 km. The first normalized the relative densities to a constant; the second normalized them to the NRL-MSISe00 empirical model, which has a strong semiannual component; and the third normalized them to the CPC analyses model, which has a strong annual component. In each case the density profile for every night of a composite year was found by averaging the nighttime density profiles in a 31-day by 11-year window centered on that day. Despite the different normalizations, many common features were found in the seasonal behavior of the densities. One is a large seasonal variation maximizing in June at $\sim$70 km. Another, above 80 km was a large shift in the maximum to earlier in the year. While these relative densities provide much useful information about mesospheric behavior, the current lidar upgrade will add an absolute. [Preview Abstract] |
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G1.00004: Progress Towards Real-Time Radiation Measurements on Aircraft L. Duane Bell, W. Kent Tobiska, Robert W. Schunk, Donald D. Rice The Space Weather Center (SWC) at Utah State University has created a team to deploy and obtain radiation effective dose rate data from dosimeters flown on commercial aircraft. The objective is to improve the accuracy of radiation dose and dose rate estimates for commercial aviation flight crews. There are two general sources of radiation exposure for flight crews: (1) the ever-present, background galactic cosmic rays (GCR), which originate outside the solar system, and (2) the solar energetic particle (SEP) events (or solar cosmic rays), which are associated with solar flares and coronal mass ejections lasting for several hours to days with widely varying intensity. The Automated Radiation Measurements for Aviation Safety (ARMAS) project is making substantial progress, currently implementing dosimeters flown in commercial aircraft to provide and improve sample data collected for the Nowcast of Atmospheric Ionizing Radiation for Aviation Safety (NAIRAS) estimates. We report on the results of our flights and the calibrations of the dosimeters. [Preview Abstract] |
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G1.00005: Coarse-graining systems biology models with Information Geometry Dane Bjork, Mark Transtrum Microscopically, biological signaling pathways can be very complex, involving a large number of bio-chemical reactions organized to perform specific cellular functions. In spite of the immense complexity of these systems when modeled at the bio-chemical level, systems often have an elegant simplicity when modeled at a more abstract, coarse-grained level. For example, numerous chemical reactions may coordinate to form an effective feedback loop. Understanding and modeling the relationship between the microscopic components and the macroscopic function is an important, challenging problem that is central to systems biology. Using information geometry, we systematically coarsen models from the bio-chemical level into effective models of the emergent biology. The coarse-grained models remain written in terms of the the microscopic parameters but vividly illustrate the emergent control mechanisms, such as feedback loops, that control the system. [Preview Abstract] |
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G1.00006: Power law structure of the ISM: HI, CO and IR fractal dimension analysis in nearby galaxies Lorraine Bowman, Dave Westpfahl, Juergen Ott The properties of turbulence in galaxies are a fundamental part of our understanding of the ISM as a complex and dynamic system. Turbulence can be probed by analyzing the fractal dimension of contours of the gas. The fractal dimension of an object is linked to its change of detail with change of scale. Any structure with non-integer fractal dimension obeys a power law. The Things (HI), Heracles (CO) and Sings (IR) surveys share a common galaxy sample from which six galaxies was selected based on their orientation in order to avoid any inclination effects. For each galaxy, the HI, 70 micron IR and CO intensity distribution maps and proton maps (obtained by converting the CO to H2 and adding the HI) were analysed.The fractal dimension of contours for each map were found to have overall different trends and different averages over intensity. This hints that the the turbulence has different effects, and likely different causes in the various constituents of the ISM. In particular, the dust phase (70 microns IR) and the gas phases (HI and CO) have different fractal dimensions. We discuss here the meaning of these results. [Preview Abstract] |
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G1.00007: Standardized AGN Fields for Photometric Reverberation Mapping Carla June Carroll, Michael D. Joner We present standardized Johnson/Cousins BVR photometry for comparison stars in the fields of several Active Galactic Nuclei. Our targets are part of a larger project using reverberation mapping techniques to determine the internal structure of the active region and to estimate the mass of the central black hole. We plan to present standard stars for fields including Zw 229-015, KA 1858, Mrk 817, Mrk 50, and NGC 4051. The next step will be to produce well standardized light curves for the active galaxies. All data for this project have been secured using the 0.91-meter telescope at the BYU West Mountain Observatory. [Preview Abstract] |
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G1.00008: Influence of Externally-applied Magnetic Fields on initial Ultracold Plasma Expansion Rates Wei-Ting Chen, Jacob Roberts Ultracold plasma expansion is influenced by the application of external magnetic fields even at the relatively small field magnitude of 0.1 mT. We present recent measurements of the short-time acceleration in ultracold plasma expansion under the influence of such applied magnetic fields. The observation of this acceleration has implications for electron diffusion rates in the ultracold plasmas, and has implications for efficient loading of ultracold plasmas into trap potentials. [Preview Abstract] |
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G1.00009: Diverse Light Emissions from Epoxy Due to Energetic Electron Bombardment Justin Christensen, Justin Dekany, J.R. Dennison Dielectric materials subjected to energetic electron fluxes can emit light in several forms. We have observed three distinct types of emissions: (i) short-duration (\textless\ 1 ms), high-intensity electrostatic discharge (ESD) or ``arc'' events; (ii) intermediate-duration, high-intensity events which begin with a bright arc followed by an exponential decay of intensity ($\sim$ 10 to 100 se decay constant), termed ``flares''; and (iii) long-duration, low-intensity emission, or cathodoluminescence, that continues as long as the electron flux is on. These events were studied for bulk samples of bisphenol/amine epoxy, using an electron gun with varying current densities (0.3 to 5 nA-cm$^{-2})$ and energies (12 to 40 keV) in a high vacuum chamber. Light emitted from the sample was measured with high-sensitivity visible and near-infrared video cameras. We present results of the spatial and temporal extent for each type of event. We also discuss how absolute spectral radiance and rates for each type of these events are dependent on incident electron current density, energy, and power density and on material type, temperature, and thickness. Applications of this research to spacecraft charging and light emissions are discussed. [Preview Abstract] |
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G1.00010: How Certain is the Heisenberg Uncertainty Relation? Jacob J. Collings, Jean-Francois S. Van Huele Since Heisenberg introduced the relation \(p_1 q_1 \sim h\) in 1927 (Zeitschrift f\"{u}r Physik, 43, 172), great effort has been made to refine this expression and better understand its meaning. At least two completely different interpretations of Heisenberg's original relation have been developed; namely, an uncertainty (or indeterminacy) principle and an error-disturbance relation. In this contribution we emphasize the difference between these two manifestations of Heisenberg's original relation: on the one hand, a lower bound for the product of the standard deviations of non-commuting operators, and on the other hand, the intrinsic error and disturbance that occur in the measurements of complementary observables. It is especially this last relation that is currently the subject of debate. We review the concepts behind certain proposed useful reformulations of this relation and the experimental evidence for their validity. We illustrate the different relations with concrete examples using spin measurements. [Preview Abstract] |
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G1.00011: Analytical modeling of line shapes in multidimensional spectroscopy Rebecca Conrad, Mark Siemens Two-dimensional coherent spectroscopy (2DCS) is a powerful tool that has provided new insight into decoherence dynamics and coherent energy transport in biological and nanostructured materials. In order to determine physical properties from experimental 2D spectra, comparisons must be made to calculations based on the Optical Bloch Equations (OBEs). In this work, analytical and graphical models were produced to discover more about the connection between fundamental physical properties of materials and spectroscopic line shapes. We used the Projection-Slice theorem of Fourier transforms to simplify the calculation by rotating the solution to the OBEs to a diagonal/cross-diagonal space, which enabled an analytical solution. In contrast to numerical computational models used in the past to simulate solutions to the OBEs, our analytical representation is much more efficient, and therefore provides a faster and more direct way to analyze experimental data. [Preview Abstract] |
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G1.00012: FalconSAT-7: A CubeSat Deployable Solar Telescope Thomas Dickinson The United States Air Force Academy's Department of Physics is building FalconSAT-7, a membrane solar telescope. The primary optic is a photon sieve -- a diffractive element consisting of billions of tiny holes in a polymer sheet. Due for launch in 2015, FalconSAT-7 will serve as a pathfinder for future missions in lightweight, high-resolution, space-based surveillance. [Preview Abstract] |
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G1.00013: Study of ion transport in sodium/proton antiporter proteins by molecular dynamics simulations David Dotson, Chiara Lee, David Drew, Alexander Cameron, Oliver Beckstein Na+/H+ antiporters serve a vital role in cell homeostasis. New crystallographic X-ray structures for two antiporters exhibit two different conformations: a cytoplasmic-open one (NhaA from Escherichia coli) and a periplasmic-open one (NapA from Thermus thermophilus). NhaA and NapA show low sequence identity but high structural similarity, including a set of highly conserved residues at the sites considered to be vital for transport. The way in which these transporters operate at the molecular scale remains largely undetermined, but using molecular dynamics computer simulations to study the interaction of Na+ ions with the transport proteins affords us new insights. We identify likely ion binding sites in the inward and outward facing conformations, noting that Na+ binding is dependent on the protonation state of a conserved aspartate residue. We also identify a conserved salt bridge that can be destabilized by Na+ binding. Taken together, the combination of structural and simulation data suggests a new model for ion binding and transport for this class of antiporter. [Preview Abstract] |
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G1.00014: Seeing the Cosmos at 1440 MHz Gregory Erickson Hydrogen is the most plentiful element in the universe. Relaxation of energetic excited states of H emit light; the most intense emission is at a wavelength of 21 cm. This wavelength is much too long for detection in the visible part of the spectrum, so a radio telescope must be used to study these emissions. For this reason, construction and troubleshooting of a radio telescope is underway at Utah State University to study the universe at this 1440 MHz frequency. We present the design of the instrument, along with a status report of its construction and testing. Once the telescope is fully functional, a map of the sky will be acquired to determine the accuracy of the instrument and other experiments can then be underway. [Preview Abstract] |
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G1.00015: Physics of Superluminal Communication and Estakhr Relativistic Omega Factor Ahmad Reza Estakhr Superluminal communication is a process by which one might send information at FTL (Faster Than Light). I try to developed this idea in detail and with mathematical rigor. The velocity of particle (information) is represented by the group velocity $v_g$. if $v_g\ge c$ then $\gamma=\frac{-i}{\sqrt{\frac{v_g^2}{c^2}-1}}=-i\Omega$ that which means $\gamma$ (Lorentz factor) is an imaginary number (at $v_g\ge c$), that can be written as a real number multiplied by imaginary unit $i$, which is defined by its property $i^2=-1$. and this is $\Omega=\frac{1}{\sqrt{\frac{v_g^2}{c^2}-1}}$ Estakhr Omega factor. then kinetic energy of FTL particle is Complex number $k=E-E_o=-E_o(i\Omega+1)$. we still use Lorentz Symmetry, $\gamma^2-\gamma^2\beta^2=1$ which means faster than light is particle-like, $i^2\Omega^2-i^2\Omega^2\beta^2=\Omega^2\beta^2-\Omega^2=1$. The phase velocity can be found from $v_{ph}=\frac{c^2}{v_g}$, this shows that the phase velocity of FTL particle is less than the speed of light $v_{ph}=\frac{c^2}{v_g\ge c}\le c$. which means that speed of material particles can exceed $c$ but finally, the product of the group and phase velocities is equal to $c^2$, in general: if $v_g\le c$ then $v_{ph}\ge c$, if $v_g\ge c$ then $v_{ph}\le c$, if $v_g=c$ then $v_{ph}=c$ i.e., $v_{g}v_{ph}=c^2$. [Preview Abstract] |
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G1.00016: Competition enhances stochasticity in biochemical reactions Taylor Firman, Kingshuk Ghosh We investigate the complex interplay between competition and stochasticity using coupled complexation reactions, (i) $A + B \leftrightarrow AB$ and (ii) $A + C \leftrightarrow AC$, as the model system, a reaction scheme common in biology. Within the master equation formalism, we compute the exact distribution of the number of complexes to analyze equilibrium fluctuations of several observables, which reveals that the presence of competition from one reaction can enhance fluctuation in the other. We provide quantitative estimates of this enhancement for different combinations of rate constants and reactant molecule quantities typical to biology. We notice that fluctuations can be significant even when two of the reactant molecules (say $B$ and $C$) are infinite in number, maintaining a fixed stoichiometry, while the other reactant ($A$) is finite. This is purely due to the coupling mediated via resource sharing and is in stark contrast to the single reaction scenario, where large numbers of one component ensure zero fluctuation. These observations indicate that averages can be a poor representation of the system, hence analysis that is purely based on averages such as mass action laws can be potentially misleading in such noisy biological systems. [Preview Abstract] |
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G1.00017: Molecular Gas in the Andromeda Galaxy Benjamin Gerard, Jeremy Darling, Nikta Amiri We present results from an Andromeda Galaxy (M31) survey of star-forming regions based on 24 $\mu$m luminosity for H$_{2}$O masers, NH$_{3}$ (1,1) and NH$_{3}$ (2,2) lines, and Hydrogen recombination lines (H66$\alpha$). Although five H$_{2}$O masers were detected in the initial survey of 206 regions towards M31, we do not detect additional masers in a follow up survey of 300 similar compact 24 $\mu$m regions. We do not detect NH$_{3}$ (1,1), NH$_{3}$ (2,2), or H66$\alpha $ lines in any of the 506 regions. The typical rms noise for 3.3 km s$^{-1}$ channels in individual spectra is 2.5 mJy. Additionally, averaging all 506 spectra, shifted to the correct radial velocity, yields no detection for H$_{2}$O, NH$_{3}$ (1,1), NH$_{3}$ (2,2), or H66$\alpha $. The typical rms noise for 3.3 km s$^{-1}$ channels in stacked spectra is 0.13 mJy. The non-detection of NH$_{3}$ provides an upper limit on NH$_{3}$ column density and corresponding dense gas fraction. In calculating this upper limit, we use both Herschel infrared continuum data and CO integrated line data to independently determine the mean molecular gas mass of each region and corresponding upper limits on the dense gas fraction. [Preview Abstract] |
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G1.00018: Frequency stabilization of a silicon magneto-optical trap repump laser Jonathan Gilbert, Samuel Ronald, Siu Au Lee, William Fairbank The primary goal of this research is to trap a single silicon atom in a magneto-optical trap. The trapped atom can be photoionized and used as a deterministic ion source. This allows for the possibility of precise implantation of a single Si$^{+}$ ion into a suitable substrate, leading to a scalable production process for solid-state quantum computers. Silicon has a $^3$P$_2$-$^3$D$_3$$^{\mathrm{o}}$ cooling transition at 221.7 nm with a weak branching transition to the $^1D_2$ metastable state. To close the cooling cycle it is necessary to excite the atom from the metastable state back to the $^3D_3$$^{\mathrm{o}}$ level using a 256.26 nm repump laser. This wavelength is generated through frequency quadrupling an external cavity diode laser. Since the repump transition wavelength has not been measured accurately, but is calculated from measurements of other stronger transitions, it will be necessary to scan this laser over the range of uncertainty. Frequency stabilization of the repump laser over a tuning range is achieved by locking the second harmonic beam at 512 nm to an $^{129}$I$_2$ hyperfine peak using an acousto-optic modulator to provide the frequency offset and modulation. The absolute frequency of various $^{129}$I$_2$ peaks in the region of interest were calibrated by comparing to $^{127}$I$_2$ spectra obtained through saturated absorption spectroscopy, using a 75 MHz free spectral range interferometer as a reference scale. [Preview Abstract] |
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G1.00019: Line Scribe Defect Characterization through Electroluminescence Isaac Gonzalez, Tyler McGoffin Electroluminescence (EL) occurs when light is emitted from a material in response to a current through the material. Under forward bias, a photovoltaic device will exhibit this property. Using a CCD camera, we can collect spatially resolved information on the performance of a device. This technique can also be used with photovoltaic modules. In this poster, we will focus specifically on issues within the monolithic interconnects of full scale CIGS modules. Using varied magnifications and injection current densities and comparing these EL images to their optical counterparts allows us to diagnose these problem areas. Different combinations of partial, overlapping, and/or incomplete scribing can produce defects, and in turn, different signal responses. [Preview Abstract] |
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G1.00020: Emergent error correction in distributed controller networks David Griffin, David Peak Sparsely connected networks of sensor/controller-units have been successfully implemented in transportation and electric power systems, factory automation, and robotics applications. Usually, such distributed networks lack a central controller capable of globally coordinating unit activity; the tasks they perform, therefore, have to emerge from dynamics associated with how the units communicate. To investigate physical constraints on such communication, we studied a simple model in which the target task was to convert all controller outputs to the same on/off state in a specified time after start-up. The initial configuration of states in the network was determined by allowing each unit to respond independently to what it sensed (perhaps incorrectly) its environmental input to require. The uniform target configuration was assumed to consist of the unit state that was initially in the majority. The architecture of our network was a square array of units with communication between nearest neighbors only. We found communication rules for synchronously updating controller-unit states (in discrete time steps) that competently performed the target task with high accuracy despite strong initial disagreement between units and random persistence of incorrect unit state. Interestingly, the competent rules asymmetrically interrogate only two of a unit's four nearest neighbors (depending on what its own state is) at each time step. Our goal is to apply insights gained from this study to try to understand the structure and function of controller-like networks found in multicellular biological organisms. [Preview Abstract] |
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G1.00021: Structure and Morphology of Gold Nanoparticles Revealed with the Aid of Coherent X-Ray Diffraction James Hanson, Kate Page, S. Manna, R. Herder, O.G. Shpyrko, Eric Fullerton, Edwin Fohtung Exceptional optoelectronic properties with applications in plasmonics, biosensing, and cancer therapy have been manifested by transition metal nanostructures. New nanostructure synthesis techniques have enabled precise control over the sizes/shapes of metal nanoparticles, leading to exotic morphologies that cannot be properly characterized using standard techniques. The optical response of these nanoparticles is size/shape dependent and locally variable. This sensitivity to morphology makes precise control over the growth of these nanoparticles and knowledge of their external/internal structures essential. One example is five-fold-twinned decahedral and icosahedral Au nanoparticles; which are strained as a result of their geometry. We present a detailed analysis of the local structure of a single Au nanoparticle by mapping the strain field from Coherent X- ray Bragg diffraction patterns. Our results confirm the presence of a disclinations within the structures consistent with the commonly accepted strain model, we however observe shear gradients. A comparison of the retrieved strain fields with finite-element calculations demonstrates the effects of elastic anisotropy on the strain state of these particles. [Preview Abstract] |
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G1.00022: Domain Morphology of Co/Pt Ferromagnetic Thin Films Kelsey Hatch I work with Co/Pt ferromagnetic thin films. The films are made of 50 bi-layers of Co and Pt. This layering causes the magnetic domains within the Co layers to align perpendicular to the film. My goal is to better understand the magnetic domain morphologies of Co/Pt thin films in the presence of a magnetic field. I apply magnetic fields of various strengths to a sample with a Vibrating Sample Magnetometer (VSM). The sample's domain depends on its magnetic history, which creates a hysteresis loop when plotting the magnetic domain vs the field applied. After each application I use Magnetic Force Microscopy (MFM) to map the domains of the sample at remnance. The hysteresis causes domains to develop differently for different field strengths, resulting in domains that appear either maze-like or bubbly. By analyzing the MFM images I am able to correlate field strength to the domain morphology. [Preview Abstract] |
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G1.00023: Microwave pulse compression utilizing nonlinear spin waves in magnetic thin films Pasdunkorale Janantha, Boris Kalinikos, Mingzhong Wu Narrow microwave pulses are desired for many microwave applications. In this presentation, a novel pulse compressor is proposed. The pulse compression is realized through soliton-associated techniques which are widely known and used in optics to compress optical pulses. The experiments used yttrium iron garnet thin films as the dispersive nonlinear media to compress microwave pulses. The operational frequency is in the GHz range and could be tuned by varying the bias magnetic field. Compression rates of up to 7 times were observed. Due to the simplicity and tunability of the configuration, the compressor has a promising future for potential applications in radar and telecommunication systems. [Preview Abstract] |
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G1.00024: Detection of Water Masers Toward YSOs in the LMC Adam Johanson, Victor Migenes We present results from a search for water maser emission toward three regions of massive star formation in the Large Magellanic Cloud (LMC). Six water maser spots were detected toward two of the regions, including one region with no known previous emission. Four of the maser spots are found to be associated with massive young stellar objects (YSOs). One maser spot appears to identify a previously unknown massive YSO. Another maser spot is associated only with a filament due to local enhancement of the interstellar medium. We argue that this may be the first extragalactic maser associated with a low-mass YSO. The third region hosts a newly discovered 22 GHz continuum source, also associated with a massive YSO. This illustrates the usefulness of masers as probes of the star formation process, both at a local and galactic scale. [Preview Abstract] |
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G1.00025: Micro-variability of AGN Markarian 421 Jeremy Judge Several Active Galactic Nuclei (AGN) have been observed in collaboration with the international group of scientists, VERITAS. These AGN are modeled as super massive black holes in the centers of young galaxies, and have a history of flares in the very high energy gamma-ray range. The presentation will concentrate on the micro-variability of the brightness of a single object, Markarian 421, over the course of select nights over several months. These observations were made in the optical spectrum, using yellow, red, and blue filters. Micro-variability observations are crucial because they give us important clues as to the mass, size, and radiation mechanism (including high energy particle jets). [Preview Abstract] |
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G1.00026: Increased X-ray Yield from Femtosecond Laser Irradiation of Vertically Aligned Nanostructures David Keiss, Amanda Townsend, Clayton Bargsten, Reed Hollinger, Mike Purvis, Chris Benton, Jorge Rocca, A. Pukhov, A. Prieto, V. Shlyaptsev Our purpose is to demonstrate a novel approach for converting optical laser energy pulses into bright picosecond x-ray pulses at a high conversion efficiency. In order to do this, a high contrast, femtosecond Ti:saph laser is used to irradiate vertically aligned nanostructure targets. This allows for the volumetric heating of the nanowire structure, creating multi-KeV temperature, near solid density plasmas with increased X-ray yields due to the greatly decreased cooling lifetime to hydrodynamic lifetime ratio-- a key component in conversion efficiency. Using a set of 12 filtered Si diodes and a bent Mica crystal spectrometer, we monitored the x-ray yield and spectra in different regions on a shot by shot basis. We have measured a conversion efficiency of 5{\%} for hv\textgreater 900eV in 2 pi radians for Au wires irradiated with pulses of 5x10\textasciicircum 18Wcm\textasciicircum -2.~ [Preview Abstract] |
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G1.00027: Critical Field and Temperature of a Frustrated Antiferromagnetic Ising Model in the Mean Field Approximation Richard Krantz A long-ranged, one-dimensional, antiferromagnetic Ising model on a two-sublattice Maximally Even (ME) lattice has been developed in the Mean Field Approximation (MFA). Douthett and Krantz [1996] and Krantz, Douthett, and Doty [1998] have shown that an alternative distribution of sites on a one-dimensional lattice, a so-called Maximally Even (ME) Distribution, can be used to describe unusual magnetic orderings of antiferromagnetic Ising systems. When the magnetization of the ``down'' lattice approaches zero the lattice makes a transition to the paramagnetic state. The magnetic field at which this occurs is the critical field. In the limit of zero applied magnetic field the temperature at which the net magnetization of the lattice goes to zero, the so-called critical temperature, can also be evaluated. Both the critical field and the critical temperature depend on: 1) the structure of the lattice -- the distribution of up and down lattice sites, 2) the number of neighboring interactions accounted for, and 3) the strength of the interaction between neighboring spins. The traditional Ising model is limited to only near-neighbor pairings. This work demonstrates that modeling a one-dimensional antiferromagnetic Ising lattice as a two-sublattice ME lattice in the MFA allows us to describe the critical field and critical temperature of frustrated one-dimensional spin systems in terms of long-ranged spin interactions and the distribution of up and down lattice sites. [Preview Abstract] |
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G1.00028: Mother's Day Gift from the Sun: Modeling the Response of the Ionosphere to X-Class Solar Flares Maggie Lewis, Jan J. Sojka, Michael David, Robert Schunk, Joseph B. Jensen, Michael Nicolls, Tom Woods, Frank Eparvier The following study was performed to better understand the effects of solar flares on the Earth's ionosphere, focusing on the large X class solar flares that occurred over Mother's Day weekend 2013. NASA's EVE instrument aboard the Space Dynamics Observatory (SDO) satellite measures the irradiance spectrum of the Sun continuously, and data is available in real-time. The sunlight causes ionization of nitrogen and oxygen atoms and molecules in the upper atmosphere thus creating the ionosphere. The important part of the solar spectrum for this ionization is the X-ray and ultraviolet light. The X-class solar flares occur in from solar eruptions that increase the X-ray irradiance by over a 1000 times normal. Using the data collected by EVE to fuel the Time Dependent Ionospheric Model (TDIM), a model of how the ionosphere reacts and changes with regards to Sun's light is simulated. The TDIM models of the ionospheric composition and behavior are then compared to empirical measurements of the ionosphere made by the Poker Flats Incoherent Scatter Radar (PFISR). The PFISR radar is located near Fairbanks, Alaska and operated continually such that a detailed history of how the ionosphere is responding to solar variations is obtained. These variations include the response to the short duration, 30 to 60 minute, X-class flares. [Preview Abstract] |
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G1.00029: Sputtering Growth and Ferromagnetic Resonance Characterization of Nanometer-Thick Yttrium Iron Garnet films Tao Liu, Houchen Chang, Yiyan Sun, Michael Kabatek, Mingzhong Wu, Vincent Vlaminck, Axel Hoffmann, Longjiang Deng High-quality nanometer-thick epitaxial yttrium iron garnet (YIG) films have been grown on gadolinium gallium garnet substrates by magnetron sputtering. The films had a thickness range of 5 to 30 nm and exhibited same crystalline orientation as the GGG substrates. The surface roughness of smooth films can be as small as 0.1 nm, which was very close to the roughness of GGG substrate. The ferromagnetic resonance (FMR) profiles can be fitted nicely with Lorentzian functions, but not with Gaussian functions. This indicated that the films had high uniformity. The FMR linewidth were in the range of 6 to10 Oe at 9.48 GHz and varied with both the sputtering and annealing conditions, as well as the crystalline structure of the GGG substrate. For films with very smooth surfaces, the FMR linewidth increased linearly with frequency and the damping constant was about 0.001. In contrast, for films with big grains on the surface, the linewidth-frequency response was strongly nonlinear. [Preview Abstract] |
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G1.00030: Time Dependent Conductivity of Low Density Polyethylene Phil Lundgreen The time independent conductivity of Low Density Polyethylene (LDPE) is useful in determining rates of conductivity based on intrinsic properties of a material. A simple, yet elegant, parallel plate capacitor setup allowed for data collection which extended beyond 170 hours. Through precise measurements the different stages of charge distribution were determined to the level of 300E-16 A. Through the use of data analysis programs the dielectric constant and dispersion constant were both determined for LDPE and then compared with a simple, macroscopic, first-principles model to determine the quality of the fit. [Preview Abstract] |
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G1.00031: Development Of Gas-Electron Multiplier Based Time Projection Chamber in MAMI Crystal Ball Mathew Mehrian, Oliver Steffen, Martin Wolfes, Wolfgang Gradl, William Briscoe Equipment development project looking for a faster and more reliable replacement for the multiwire proportional chamber (MWPC) charged particles tracking system in the MAMI Crystal Ball in Mainz, Germany. With the gas electron multiplier (GEM) based time projection chamber (TPC) you will be able to perform a whole series of experiments that require higher beam rates and better resolution. One such experiment is the search for the f0 and a0 mesons. [Preview Abstract] |
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G1.00032: Optical properties of Sm doped CeO$_{2}$ thin films produced by liquid solution deposition K.N Mitchell, C.A Rodriguez, T. Willett-Gies, Y. Li, S. Zollner Cerium(IV) oxide (CeO$_{2}$ or ceria) is a transparent, insulating oxide of the rare earth metal cerium. Ceria is an ionic conductor with applications in fuel cells, as a catalyst, or photovoltaic water splitting (hydrogen production). The films studied here were produced by liquid solution deposition followed by annealing. Additionally we investigate the effect of Sm doping (up to 20{\%}) of ceria. The rare earth metal samarium usually forms a sesquioxide Sm$_{2}$O$_{3}$. Therefore, doping ceria with Sm is expected to lead to the formation of oxygen vacancies, which enhances the ionic conductivity of ceria. Our ellipsometry spectra can be described very well in the transparent region (below 3 eV) using a Tauc-Lorentz dispersion model for ceria. Once the thickness parameters have been determined, we obtain the optical constants of CeO$_{2}$:Sm using a basis spline expansion. As expected from Kramers-Kronig consistency, we find a significant reduction of the height of the main absorption peak at 4 eV. The direct band gap, however, remains at 3.7 eV, independent of Sm content. We will also report XRD, AFM, and Raman results for our Sm-doped ceria films. [Preview Abstract] |
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G1.00033: Winter Climatology of Short-Period Polar Mesospheric Gravity Waves Observed Over Poker Flat Research Range, Alaska (65$^{\mathrm{o}}$N, 147$^{\mathrm{o}}$ W) Michael Negale, Kim Nielsen, Mike Taylor, Dominique Pautet, Margit Dyrland Short-period gravity wave observations over the Arctic region are few and their impact on the Arctic mesosphere lower thermosphere region via momentum deposition is of high interest. The Mesospheric Airglow Imaging and Dynamics project was initiated in January 2011 to investigate the presence and dynamics of these waves over the interior of Alaska. Observations were made from Poker Flat Research Range (PFRR) using an all-sky imager. This site provides an exceptional opportunity to establish a long-term climatology of short-period gravity waves in the Arctic Region. We present summary measurements of prominent gravity waves over two consecutive winters and compare their characteristics with recent observations at Resolute Bay, Canada (75$^{\mathrm{o}}$ N), ALOMAR Station, Norway (69$^{\mathrm{o}}$ N), Svalbard (78$^{\mathrm{o}}$ N), and Rothera Station (76$^{\mathrm{o}}$ S). The wave parameters measured at PFRR were found to be similar to the other high-latitude sites, except for the wave headings. The waves at PFRR exhibited dominant eastward motion, while the other observations reported westward motion. To investigate this wave directionality, we look at the effects of critical level filtering. [Preview Abstract] |
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G1.00034: Infrared and Visible Dielectric Properties of (LaAlO$_{3}$)$_{0.3}$ (Sr$_{2}$AlTaO$_{6}$)$_{0.7}$ Timothy Nunley, Travis Willett-Gies, Stefan Zollner LSAT (LaAlO$_{3}$)$_{0.3}$ (Sr$_{2}$AlTaO$_{6}$)$_{0.7}$ is a crystal with a perovskite structure that has a good lattice match for many oxide materials and could replace LaAlO$_{3}$ and SrTiO$_{3}$ substrates. We measured the pseudo-dielectric function of LSAT from 0.6 to 6.3 eV using spectroscopic ellipsometry. The dielectric function was then modeled allowing us to obtain the optical band gap of 4.9eV. A transmission series was also taken in vacuum from 77 K to 600 K in 25 K steps showing that the change in the band gap of LSAT is inversely proportional to the change in temperature. Transmission measurements were also taken in air at room temperature allowing us to calculate and plot the absorption coefficient as a function of photon energy. Fourier-transform infrared (FTIR) ellipsometry was also performed from 250 to 8000 cm$^{-1}$. The dielectric function in this range was then modeled using a factorized dispersion model containing transverse (TO) and longitudinal (LO) optical phonon energies and independent broadenings for each mode. Five TO phonons were found at 284, 392, 444, 663, and 756 cm$^{-1}$. There were five corresponding LO phonons located at 355, 434, 551, 753, and 788 cm$^{-1}$. A possible strong TO mode located at 150 cm$^{-1}$ is below our spectral range. [Preview Abstract] |
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G1.00035: Low Band Gap Small Molecule Acceptors for Organic Photovoltaics David P. Ostrowski, Unsal Koldemir, Alan Sellinger, Sean E. Shaheen Organic photovoltiacs (OPVs) have demonstrated solar power conversion efficiencies in the regime of 10-12{\%} from several classes of materials, including conjugated polymers and small-molecules. Of note, in each of the classes, the electron-accepting molecule is based on C$_{60}$. While C$_{60}$ is a very effective electron-acceptor and transporter, it has several non-optimal properties, including low optical absorption strength in the visible spectrum as well as the difficulty required to tune its optoelectronic properties through changes in chemical composition or substituents. Here we present results on a family of small molecule acceptors based on a core unit of benzothiodiazole (BT). The optoelectronic properties, specifically optical band gap and Lowest Occupied Molecular Orbital (LUMO), of these small molecules are readily tunable through addition of substituent groups onto the BT core. A library of these small molecule acceptors has been synthesized with broad absorbance bands of roughly 200 nm, which vary in peak absorbance from 400 nm to 640 nm. Additionally, the higher energy LUMO level of these materials, 0.3 eV higher than the C$_{60}$ derivatives, results in OPVs with open-circuit voltages (V$_{\mathrm{oc}})$ close to 1 V. The studies presented investigate overall device performance and compare the efficiencies of the two mechanisms for charge generation: channel 1 (light absorbed in donor with sequential electron transfer to acceptor molecule) and channel 2 (light absorbed in the acceptor with sequential hole transfer to donor molecule). [Preview Abstract] |
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G1.00036: Puzzling Results from a new Spacecraft Plasma Sensor Experiment Steven Owens Current space plasma sensors require multiple high voltage power supplies and a spinning spacecraft to acquire a full reading of the surrounding plasma. These requirements drive the cost of launching space plasma sensors higher, decreasing their true effectiveness (no launches means no data). To resolve this issue, a new design for plasma spectrometers is needed. Such a device must be capable of taking ultrafast measurements using only one high voltage power supply. One solution, designed by Los Alamos National Laboratory, is called the 2-Pi Plasma Spectrometer, or 2PiS. During the first phase of the project, a prototype was built to compare proof of concept against simulated data. Testing the prototype produced an odd result: the prototype performed better than the simulation predicted. To understand why this occurred and to exploit the problem in the future, the background theory was tested in the simulation. After the equations proved to be correct, internal parts of the 2PiS were skewed from perfect in a simulation to see what effect this would have. While skewing the plates does have some effect, no single skew could cause the difference seen in the data. [Preview Abstract] |
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G1.00037: Asymmetric disk heating in an extreme binary, epsilon Aurigae: a useful tool for unveiling a system's unknowns Richard Pearson Epsilon Aurigae is a 27-year eclipsing binary system consisting of a large, warm F0 star and a hidden companion inside a semi-grey, opaque disk. The evolutionary state (and hence, the characteristics of the system components) is not well-defined due to a large uncertainty in the determined distance. By using the observed disk temperatures, I attempt to resolve the distance discrepancy by analytic and numeric means. Both methods require investigation of the disk properties. Examination of disk temperatures in epsilon Aurigae creates a blueprint for a novel way of determining dust properties and other characteristics of additional dusty systems. This is another tool for extracting information from systems with limited known quantities. I am grateful to the estate of William Herschel Womble for the support of astrophysics at the University of Denver. [Preview Abstract] |
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G1.00038: Atomic Oxygen Modification of the Nanodielectric Surface Composition of Carbon-Loaded Polyimide Composites Kelby Peterson, JR Dennison Black Kapton is a nanodielectric composite of carbon particles (100-500 nm) embedded in an insulating polyimide polymer matrix (100-5000 nm depth). Analysis of this nanodielectric composite has been done via optical imaging, scanning electron microscopy, and energy-dispersive x-ray analysis in order to gain insight into its nanodielectric properties. The insulating polyimide is known to be inert and impervious to strong bases and acids, but is affected by atomic oxygen exposure. We have observed changes in the surface structure and relative carbon-polymer concentrations in MISSE-6 samples that were exposed to the low earth orbit environment for 18 months outside the International Space Station. The MISSE-6 sample tray arrangement permitted studies of the effects due to varied atomic oxygen exposure. MISSE samples received maximum atomic oxygen exposure on the ram side with decreased exposure on the wake and shielded sides, respectively. Early observations suggest that the atomic oxygen modifications reduce the polymer matrix on the surface, whilst the carbon-loaded regions remain largely unaffected by the exposure. Affects of the surface modifications on spacecraft charging and cathodoluminescence will be discussed. [Preview Abstract] |
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G1.00039: Optical Properties of Bulk Nickel as a Function of Temperature Laura Pineda, Stefan Zollner Nickel is a silvery-white metal, element number 28 in the first row of the transition metals. It is ferromagnetic below the Curie temperature (TC=630 K), i.e., it retains a net magnetization in the absence of a magnetic field. When heated above the Curie temperature, it becomes paramagnetic and loses its magnetization. The literature reports a distinct change in the slope of the DC electrical resistivity of nickel versus temperature near the Curie transition. Similarly, a change in the optical reflectivity of nickel has been reported at TC. We therefore used spectroscopic ellipsometry to measure the complex refractive index of nickel with very high precision from 77 to 800 K. In our data for n(T), we find deviations from linearity near 150 K and near 590 K. The refractive index also changes again at even higher temperatures. We believe that our data are affected by two factors: (1) The native oxide on the Ni surface disintegrates above 700 K, leading to a change in the surface condition of our sample. (2) The optical constants also change near the Curie temperature. Work is in progress to separate the two observed phenomena. [Preview Abstract] |
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G1.00040: Functionalizing Carbon Nanotube Forests with 1,5-diaminonaphthalene Benjamin Pound, T.C. Shen Carbon Nanotube (CNT) Forests are vertically grown carbon nanotubes. They can be as tall as millimeters, with radii from less than one nanometer (single-walled) to tens of nanometers (multi-walled). Their high surface area to volume ratio provides a unique material system for biosensor applications. However, the CNT surface does not provide covalent bonding sites to many antibodies of interest. One approach is to attach linker molecules with aromatic rings via $\pi $-stacking to the CNT surface and activating the linker molecules to bind covalently to specific antibody molecules. Unfortunately, the conventional solution-based functionalization approach often leads to collapse of the CNT forest and hence a significant loss of binding sites. In this presentation we report our study of depositing 1,5-diaminonaphthalene on CNT forest by a vapor deposition method. We characterize the amount of deposition by fluorescence spectra. We plan to pattern CNT forest to further enhance the surface coverage by varying the geometry of CNT forest columns. [Preview Abstract] |
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G1.00041: Satellite and Ground-Based Measurements of Mesospheric Temperature Variability over Cerro Pachon, Chile (30.3$^{\circ}$ S) Jonathan Pugmire, Michael Taylor, Yucheng Zhao, P. Dominique Pautet, James Russell Observations of mesospheric OH (6,2) rotational temperatures by the Utah State University Mesospheric Temperature Mapper (MTM) located at the Andes Lidar Observatory, Cerro Pachon, Chile (30.3$^{\circ}$ S, 70.7$^{\circ}$ W) reveal a large range of nightly variations induced by atmospheric gravity waves and tides, as well as strong seasonal oscillations. This study investigates MTM temperature variability over the past 4 years comprising over 800 nights of high-quality data and compares the results with MTM measurements from Maui, Hawaii (2001-2005) and coincident mesospheric temperature measurement by the SABER instrument on the NASA TIMED satellite. [Preview Abstract] |
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G1.00042: Investigating Proto-Planetary Nebulae through Angular Differential Imaging Rebecca Rattray, Toshiya Ueta Studying the Proto-Planetary Nebula (PPN) stage of a star's life sheds light on the critical mass-loss mechanism that leads to the morphological change from spherically symmetric to axisymmetric circumstellar material. However, when studying material very faint in reflection so close to a star, the brightness of the star itself becomes prohibitive. Therefore, in order to study the circumstellar material more effectively, it is necessary to block out the central star. The method of Angular Differential Imaging (ADI), used in this research, creates a better characterization of the point-spread-function (PSF) of the central star for more effective subtraction than previous PSF subtraction techniques. ADI has successfully been used to verify extrasolar planets, but this is one of the first attempts at adopting ADI techniques for extended structures as opposed to point sources. In this study, ADI techniques were applied to PPN observations to better study the most recent mass-loss histories of PPNs. Data for the PPNs were taken at the Near Infrared Coronographic Imager (NICI) at Gemini South between March and September 2012. New details on the circumstellar structure of 6 PPNs will be presented. [Preview Abstract] |
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G1.00043: Correlating cell morphology and stochastic gene expression using fluorescence spectroscopy and GPU-enabled image analysis Evan Shapiro, Evan Perillo, Douglas Shepherd Biological processes at the microscopic level appear stochastic, requiring precise measurement and analytical techniques to determine the nature of the underlying regulatory networks. Single-molecule, single-cell studies of gene expression have provided insights into how cells respond to external stimuli. Recent work has suggested that macroscopic cell properties, such as cell morphology, are correlated with gene expression. Here we present single-cell studies of a signal-activated gene network: Interleukin 4 (IL4) RNA production in rat basophil leukemia (RBL) cells during the allergic response. We fluorescently label individual IL4 RNA transcripts in populations of RBL cells, subject to varying external stimuli. A custom super-resolution microscope is used to measure the number of fluorescently labeled IL4 transcripts in populations of RBL cells on a cell-by-cell basis. To test the hypothesis that cell morphology is connected genotype, we analyze white light images of RBL cells and cross-reference cell morphology with IL4 RNA levels. We find that the activation of RBL cells, determined by white-light imaging, is well correlated with IL4 mRNA expression. [Preview Abstract] |
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G1.00044: Probing Ancient Mass Loss with AKARI's Extended Thermal Dust Emission Objects Rachael Tomasino, Toshiya Ueta We present the results from the calibration and analysis of 166 far-IR extended thermal dust emission objects that were observed with AKARI's FIS detector. The primary goal is to map the circumstellar shells of evolved stars in detail to excavate the ancient history of dusty mass loss. After establishing an extended aperture photometry method, we characterized the flux dependent slow transient response correction factors for each of the four wavelength bands. Using the new correction factors for extended (far-IR) emission, we present the photometric values that were calculated for the entire data set and also report our work on morphology characterization of the extended dust shells. [Preview Abstract] |
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G1.00045: Bright X-ray Sources from Ultra-high Density Matter in Volumetrically Heated Nanowire Arrays Amanda Townsend, Reed Hollinger, Clayton Bargsten, Michael Purvis, David Keiss, Chris Benton, Amy Prieto, Alexander Pukhov, V.N. Shlyaptsev, Jorge Rocca Trapping femtosecond laser pulses of relativistic intensity within ordered nanowire arrays results in the volumetric heating of matter to multi-KeV, near solid density plasmas. Using high contrast pulses of 60fs FWHM duration from a frequency doubled Ti:Saph laser, we irradiated arrays of 55nm and 80nm diameter Au and Ni targets with 12{\%} of solid density at intensities of 5x10$^{18}$ Wcm$^{-2}$. We observed strong He-like line emission that surpassed the characteristic K-a emission by an order of magnitude. The Au nanowire spectrum displayed strong Au M-shell emission with unresolved 4-3 lines from ions ranging from Co-like to Ga-like Au. Filtered photodiode measurements show a $\sim$ 100x emission increase with respect to smooth solid targets for photon energies \textgreater 9keV. [Preview Abstract] |
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G1.00046: Analysis of interface node dynamics in \textit{Drosophila} during germ-band extension Timothy Vanderleest, Ashley Motlong, Marissa Kuhl, Todd Blankenship, Dinah Loerke Tissue elongation is a fundamental morphogenetic process crucial to embryogenesis and organogenesis in vertebrates and invertebrates. One widely studied example of tissue elongation is \textit{Drosophila} germ-band extension (GBE) in which an initially hexagonal array of cells approximately doubles in length along the anterior-posterior (AP) axis. This process is driven by cell intercalation where interfaces between cells along the AP axis fully contract to a common vertex and interfaces form between dorsal-ventral neighboring cells. The current model holds that intercalation is caused by anisotropic tension mediated by actomyosin contractility. Using automated computational image segmentation we have tracked the motion of cells during GBE with high spatial and temporal resolution, which includes the tracking of interfaces and interface vertices. Through cross correlation analysis on the motion of vertices of contracting AP interfaces we have found that vertex behavior is not correlated and, in fact, display independent displacements. These results are inconsistent with a tension-based model in which supracellular actomyosin networks drive coordinated node behaviors. [Preview Abstract] |
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G1.00047: Ultracold plasma expansion rate dependence on non-neutrality Craig Witte, Jacob Roberts Ultracold plasmas are formed by photoionizing a collection of laser cooled atoms. Once formed, these plasmas expand. This expansion is driven by both the thermal energy of the plasma electrons, as well as electrostatic energy owing to non-neutrality. Both the parameters can be experimentally controlled with a significant degree of independence. Combining previous work,\footnote{F. Robicheaux and James D. Hanson, Simulation of the Expansion of an Ultracold Neutral Plasma, Phys. Rev. Lett. {\bf 88}055002, (2002).}$^,$\footnote{D Vrinceanu, G S Balaraman, and L A Collins, The King model for electrons in a finite-size ultracold plasma, J. Phys. A: Math. Theor.{\bf 41} 425501 (2008).} we have developed a theoretical model designed to investigate the dependence of ultracold plasma expansion on the degree of non-neutrality of these plasmas in a parameter range relevant to experiments. We find that variations of the plasma neutrality produce non-negligible changes in predicted electron temperature evolution and plasma expansion rate. Such behavior needs to be taken into account for an accurate interpretation of ultracold plasma parameters relevant to experimental measurements. [Preview Abstract] |
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G1.00048: Detecting cosmic ray electrons in the tracking region of space borne instruments Aaron Worley, Jonathan Ormes Cosmic Ray Electrons (CREs) contribute only $\sim$ 1{\%} to the total number of particles we observe here on Earth and are of current interest because of the recently discovered rising fraction of positrons as measurements approach 1 TeV. We review our recent progress in particle identification (PID) methods using dedicated information from the tracking region of a space bourne detector. Our primary focus is the identification of CREs in the Fermi Large Area Telescope and the Calorimetric Electron Telescope, current and future missions respectively. The impact of including a dedicated PID algorithm in the tracker to improve the efficiency and rejection power of the detectors above will also be discussed. [Preview Abstract] |
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G1.00049: Plasma sheath effects in the sampler and skimmer cones of the ICP-MS Matthew Zachreson, Ross Spencer In the ICP-MS, plasma neutrality and the associated issue of the plasma potential are governed by what happens in the plasma sheath. Plasma sheaths can generally be described by two model types: collisional, where the Debye length is long compared to the mean free path; and collisionless, where the mean free path is long compared to the Debye length. In the sampler cone, the Debye length is .3 micrometers, while the ion mean free path is 5 micrometers, nearly in the collisionless regime. In the skimmer cone, the Debye length is 2 micrometers, while the ion mean free path is 400 micrometers, well into the collisionless regime. Doing a full calculation with the Direct Simulation Monte Carlo algorithm, FENIX, would involve simulating electron physics, performing electrostatic field calculations, and resolving the small Debye length, all of which are computationally expensive. To approximate sheath formation in the sampler and skimmer, a forced ion flux model is made by first estimating the number of ions per second that should recombine at the wall using a simple, planar, collisionless sheath model, and then forcing the ions near the wall to have that flux by modifying their velocities each time step. The ion loss through the sheath results in a steep drop in the ion density at the nozzle wall which both diffuses and is sheared by the nozzle flow. Another plasma effect is that the sheath inhibits electron flow to the wall, greatly reducing thermal conduction to the wall. This means that the electron temperature of the plasma in the nozzle is hardly affected by the presence of the metal wall. In particular, setting the electron temperature equal to the wall temperature at the wall is inappropriate. [Preview Abstract] |
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G1.00050: Beyond Exoplanets: Taking advantage of Kepler Object of Interest fields after the presence or absence of an exoplanet has been documented Pamela Lara Since the Kepler Mission made public its data on planet-candidates we have observed a few Objects of Interest -KOI- with our 0.9 m telescope at West Mountain Observatory to confirm or reject their nature as planets. Most of our chosen targets were found not to be planets. However, the data acquired need not be discarded since other bodies in the fields may present interesting light curves deserving of further investigation and study. This is the case for one of our KOI candidates, which turned out to be an eclipsing binary system. While performing differential photometry with stars in the field, I found a contact eclipsing binary that was not in the Kepler data base. In this poster I will present data on the new contact binary and discuss other interesting variable objects I have found in the Kepler field of view. This research was performed while participating in the Physics and Astronomy REU program at Brigham Young University during the summers of 2012 and 2013. [Preview Abstract] |
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