Bulletin of the American Physical Society
2012 Annual Fall Meeting of the APS Prairie Section
Volume 57, Number 14
Thursday–Saturday, November 8–10, 2012; Lawrence, Kansas
Session E1: Poster Session (5:30-6:30PM) |
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Room: Oread Hotel All Season's Den |
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E1.00001: Data throughput testing for the CMS pixel upgrade David Gier The Optical Hybrid converts a differential signal to an optical signal as part of the data readout chain for the CMS detector at the Large Hadron Collider at CERN. The current Analog Optical Hybrid must be updated to a Pixel Optical Hybrid which can run at the 400Mbps rate of the upcoming Pixel Detector upgrade. This project tests the optical hybrids by examining eye diagrams, simulating data streams from the detector and constructing bit error rate tester firmware. [Preview Abstract] |
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E1.00002: X-ray studies of the pixel readout for the CMS detector Jackson Young X-ray tests have been conducted on the silicon pixel particle detectors which are being used in the Compact Muon Solenoid experiment at the Large Hadron Collider. Using an X-ray box setup at the University of Kansas, a broad scope of tests from simple parameter effects to more complex multi stage tests have been performed. A fluorescence setup was made to allow the adjustment of incoming particle energy which allows one to calibrate the energy in the detectors. The trimming algorithm used to adjust the readout threshold for each pixel is also studied using X-rays. [Preview Abstract] |
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E1.00003: ABSTRACT WITHDRAWN |
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E1.00004: Astrophysical magnetic micro-turbulence: relation of diffusion of relativistic electrons to the emitted radiation spectra B. Keenan, M.V. Medvedev Kinetic (Weibel-type) instabilities are ubiquitous in astrophysical high-energy density environments, e.g., in relativistic collisionless shocks, reconnection of strong magnetic fields in neutron star and magnetar magnetospheres, interaction regions of relativistic winds from neutron stars with the interstellar medium, and so on. Such instabilities generate strong (sub-equibartition) magnetic fields which reside at small, sub-Larmor scales. Efficient electron acceleration to relativistic energies is not uncommon in such environments. Spectra of radiation emitted by these relativistic electrons, called jitter radiation, can deliver wealth of information about the internal structure of such ``Weibel turbulence.'' The small-scale fields simultaneously affect the particle transport via pitch-angle diffusion. Both effects are related and can be used to diagnose the astrophysical plasmas. Indeed, the radiation pattern is intimately related to the particle orbits and, thus, to the transport properties of the turbulence. We study such a relation between transport in and radiation from micro-scale turbulence via numerical simulations and analysis. [Preview Abstract] |
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E1.00005: Revisiting the Carrington Event: Updated modeling of atmospheric effects Brian Thomas, Keith Arkenberg, Brock Snyder The terrestrial effects of major solar events such as the Carrington white-light flare and subsequent geomagnetic storm of August-September 1859 are of considerable interest, especially in light of recent predictions that such extreme events will be more likely over the coming decades. Here we present results of modeling the atmospheric effects, especially production of odd nitrogen compounds and subsequent depletion of ozone, by solar protons associated with the Carrington event. This study combines approaches from two previous studies of the atmospheric effect of this event. We investigate changes in NOx compounds as well as depletion of O3 using a two-dimensional atmospheric chemistry and dynamics model. Atmospheric ionization is computed using a range-energy relation with four different proxy proton spectra associated with more recent well-known solar proton events. We find that changes in atmospheric constituents are in reasonable agreement with previous studies, but effects of the four proxy spectra used vary more widely than found by one of those studies. In particular, we find greater impact for harder proton spectra, given a constant total fluence. We report computed nitrate deposition values and compare to measured values in ice cores. [Preview Abstract] |
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E1.00006: Mass-Eigenstate Scattering and Conversion of Non-Relativistic Self-Interacting Flavor-Mixed Dark Matter Particles A. Ford, M.V. Medvedev Some Cold Dark Matter candidates are flavor-mixed particles. Recently, it has been shown that a collision (scattering) of two non-relativistic flavor-mixed particles, as in a self-interacting dark matter model, can cause the particles to experience mass eigenstate conversions, which in turn can ultimately lead to their escape from a trapping gravitational potential of a dark matter halo. Such a process has an important effect on the large scale structure formation and provides an elegant solution to several outstanding cosmological problems. Here we study elementary processes involving flavor-mixed particles -- elastic scatterings and conversions -- and calculate cross-sections of these processes under various conditions. Our results are of great importance for fundamental theory of the interaction of mixed particles and for understanding of the cosmological structure formation. [Preview Abstract] |
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E1.00007: Sub-nanoscale Resolution for Microscopy via Coherent Population Trapping and Coherent Population Oscillations Kishor Kapale, Girish Agarwal We present microscopy schemes to attain sub-nanoscale resolution based on two phenomena---coherent population trapping (CPT) and coherent population oscillation (CPO). The CPT based method uses three-level atoms coupled to amplitude modulated probe field and a spatially dependent drive field. Whereas, the CPO based schemes involve two-level atoms coupled to two optical fields slightly different in frequency. The modulation of the probe field (in CPT-based scheme) allows us to tap into the steep dispersion normally associated with electromagnetically induced transparency and offers an avenue to attain sub-nanometer resolution using just the optical fields. CPO-based schemes offer similar resolution as the CPT-based schemes but they are attainable in a larger class of materials. It is known that group velocity manipulations with the CPO effect have been observed in room temperature solids and biological samples as opposed to in atomic vapors and cold atomic gases in the case of CPT. This parallel allows us to extend our CPT-based work to CPO-based microscopy schemes and makes them attainable in much larger class of materials including solids and biological samples. [Preview Abstract] |
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E1.00008: Local Thermomechanical Analysis of a Microphase-Separated Thin Lamellar PS-b-PEO Film Reginald Rice We use atomic force microscopy (AFM) and hot tip AFM (HT-AFM) to thermophysically characterize a 30 nm thick film of poly(styrene-block-ethylene oxide), PS-b-PEO, and to modify its lamellar patterns having spacing of 39 $\pm$ 3 nm. AFM tip scans of the polymer film induce either abrasive surface patterns or nanoscale ripples, which depend upon the tip force, temperature, and number of scans. The evolution of the lamellar patterns is explained by the polymer film molecular structure and mode I crack propagation in the polymer combined with the stick-and-slip behavior of the AFM tip. The HT-AFM measurements at various tip-sample temperatures and scanning speeds yield several thermophysical quantities. [Preview Abstract] |
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E1.00009: Mechanical Unfolding of the NRR Domain from Human Notch 1 Ashim Dey, Katarzyna Malek, Nicoleta Ploscariu, Robert Szoszkiewicz Notch signalling in mammals is responsible for cellular processes related to embryonic development and tissue homeostasis. Problems in Notch signaling lead to many diseases, including T-cell acute lymphocytic leukemia and solid tumors in breast cancer. Exposure of the S2 site within an extracellular NRR domain of Notch is the key early event in Notch signaling. In this paper we use single molecule force-extension (FX) AFM force spectroscopy to investigate the role of mechanical force in unfolding the NRR domain from human Notch 1. We provide probability analysis of the NRR unfolding traces, which supports the sequential NRR unfolding model. Our FX AFM measurements provide us also with histogram of the N to C termini lengths related to conformational transitions within the NRR domain. By fitting multiple Gaussians to this histogram we detect four classes of events. Based on the related steered molecular dynamics (SMD) study, we associate the first two classes of events with the S2 site exposure. We obtain that their mean unfolding forces are 77.2 $\pm$ 60.4 pN and 82.2 $\pm$ 57.67 pN, respectively. These substantial molecular forces constitute a double protection barrier against any accidental S2 site exposure. [Preview Abstract] |
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E1.00010: Average Energy Approximation of the Ideal Bose-Einstein Gas and Condensate Don Lemons I introduce and use the average energy approximation according to which the particles of an ideal quantum gas all have the average energy of the system. For instance, if the N bosons that compose an ideal Bose-Einstein gas with energy E and volume V are each assumed to have the average energy E/N, the entropy is easily expressed in terms of the number of bosons N and the number of single-particle microstates n they can occupy. Because the entropy derived is a function of only N and n, and the latter is a function of the extensive variables, E, V, and N, this entropy describes all that can be known of the thermodynamics of this fluid system. In particular, the entropy recovers the Sakur-Tetrode entropy in the classical limit and at sufficiently low temperatures describes an unstable system. A thermodynamic stability analysis recovers the Bose-Einstein condensate and a two-phase region. Apart from numerical factors of order one, results are identical with those derived via standard, probabilistic methods. [Preview Abstract] |
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E1.00011: The Continuing Development of a Low-Cost Scanning Tunneling Microscope for High School and College Classrooms Brett Amen, Axel Enders, Mark Plano Clark We have been developing an inexpensive, room-temperature, atmospheric-pressure scanning tunneling microscope (STM) with atomic resolution for use in high school class rooms and undergraduate teaching laboratories. Because of a lack of consistency during coarse approach and withdrawal of the tip head using the inertial slip-stick design, we are developing a ``walker'' motion consisting of four linear piezo actuators moving independently under microcontroller control. In addition to improving the coarse motion, we also need more robust atomically sharp tips for scanning surfaces at atmospheric pressure. We are in the process of producing sharp~carbon fiber tips to make this STM an effective tool for the intended audience. [Preview Abstract] |
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E1.00012: Neutron scattering studies of glassy solid state Li electrolytes Leo Zella, Ali Zaidi, Munesh Rathore, Anshuman Dalvi, Saibal Mitra, Tom Heitmann We present characterizations, performed using two different neutron scattering techniques, on superionic materials that are good candidates for use as solid state electrolytes in next generation Li$^{+}$ ion batteries. The materials are glassy in nature and composed of a complex network of the following sub-units: Li$_{2}$O, Li$_{2}$SO$_{4}$, and 2NH$_{4}$H$_{2}$PO$_{2}$. This disordered structure is integral to its function in that it promotes Li$^{+}$ ion conduction while suppressing electron conduction, the necessary qualities of a good Li$^{+}$ electrolyte. We have implemented neutron diffraction to study the formation of crystallites upon heating of the material above 400$^{\circ}$ C. The crystallite formation is understood to be detrimental to the Li$^{+}$ ion mobility and, hence, is identified with a diminished performance in devices that require heating in their fabrication process. We have also used a triple-axis spectrometer to begin to separate out the diffuse scattering that results from the disordered structure of the material from the diffuse scattering that results from dynamic processes that occur in it. This is done by a comparative study of the energy resolved versus energy integrated scattering over the full available q-range. [Preview Abstract] |
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E1.00013: Seedling Detection in a Flatbed Scanner Image Acquisition System for Plant Growth Studies Brad R. Higgins, Tessa Durham Brooks, Christopher D. Wentworth Recent plant genome studies have made use of a low cost flatbed scanner image acquisition system to obtain a large number of image sequences showing growth of seedlings. This system has generated a significant database of images for growth studies of the model plant \textit{Arabidopsis thaliana} with varying genetic and environmental conditions. Analysis of image sequences must be automated due to the very large number of images that need to be studied. We have developed a processing algorithm and code that can identify individual seedlings and track them over time in a scanner image sequence. Our code can also remove unused parts of the image thereby saving hard drive storage requirements for the image database. The code was developed in Python using functions from the open source image processing library OpenCV. The code is available under an open source license. [Preview Abstract] |
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E1.00014: An Empirical Study of the Velocity Field for Arabidopsis Root Cells Amy E. Craig, Tracy Guy, Brad Higgins, Tessa Durham Brooks, Christopher D. Wentworth The velocity field of a plant's primary root describes the velocity of cells as a function of position measured with respect to the root apex. This field has a characteristic sigmoid shape in many plants that can be described empirically by a modified logistics function. In this study we measured the velocity field for root cells in \textit{Arabidopsis thaliana} for several different genotypes and environmental conditions using an inexpensive computer-based image acquisition and analysis system. Image analysis was done using open source software. We fit our data to the modified logistics function and determined whether there were statistically significant changes in model parameters depending on growing conditions. [Preview Abstract] |
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E1.00015: Excluded-volume effects of molecular vibrations in a one-dimensional gas James H. Taylor Some common thermodynamic properties are found for $N$ rod-like, vibrating molecules in 1D, where the length of each molecule oscillates with an amplitude determined by the molecule's internal vibrational energy. Properties are found via exact evaluation of the partition function, $Z$; to account for the different possible lengths of individual molecules, calculation of $Z$ includes integration over the internal phases describing the oscillations. For $N$ greater than 1 and large system length $L$, there is an increase in the average energy of the system at a given temperature---compared to that for molecules with fixed lengths---as well as in the entropy and isothermal compressibility; the pressure decreases, though, and there is a variable effect on the heat capacity. These alterations can be traced directly to an effective increase in the 1D volume available to the molecules, the changes being larger for higher energy states than for lower ones. The oscillations have minimal influence when $L$ is large compared to the combined length of all molecules, but dominate the behavior when the two lengths become comparable. [Preview Abstract] |
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E1.00016: High Altitude Ballooning: A Physics Experience For Undergraduate Students Timothy Stiles, Corbin Peterson, Gage DeCook, Patrick Crawford, Andrew Selep High altitude ballooning is a popular scientific activity for colleges and high schools. In this three week summer project, four undergraduate students designed and constructed a helium balloon that lofted a 3.0 kg payload to 26500 m. An Arduino Mega acted as flight computer, recording GPS position, temperature, atmospheric pressure and relative humidity during the three hour flight. The payload also carried a digital camera and GPS receiver/satellite phone to transmit locations. The payload was successfully recovered and the data analyzed by the students. This project was an ideal activity for students to learn about measurement and analysis of data and an introduction to atmospheric physics. [Preview Abstract] |
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