Bulletin of the American Physical Society
2005 Joint Spring Meeting of the Texas Sections of the APS, AAPT, and Zone 13 SPS
Thursday–Saturday, March 3–5, 2005; Nacogdoches, TX
Session AC: Poster Session |
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Sponsoring Units: TSF Chair: Robert Gruebel Room: Science Building 316 Hallway 2:30-4:00pm |
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AC.00001: The Power of Inverse Adding-Doubling (IAD) Method to Determine Optical Scattering and Absorption of Biological Media. Guang-Yin Swanland, Raylon Yow, Dhiraj Sardar The IAD method is a numerical approach to determine the optical properties of biological tissue samples by using the measurements of total diffuse reflectance and total diffuse transmittance in conjunction with the index of refraction and the thickness of a homogeneous slab of turbid medial. It can be used on slabs within or without slide glass, including slabs surrounded by a medium with a different index of refraction. The turbid slabs can have any optical thickness, albedo, or phase function. The IAD method obtains the optical properties of the slab by repeatedly using an adding-doubling method to solve the radiative transport equation until those derived properties are the closest match to the measured values. The IAD method has the advantages of accuracy and flexibility in regard to the sample. [Preview Abstract] |
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AC.00002: Electron microscopic studies of the charge-ordered structures of the bilayered colossal magnetoresistive (CMR) manganite La$_{2-2x}$Sr$_{1+2x}$Mn$_{2}$O$_{7}$ Zhiping Luo The charge-ordered structures in the bilayered colossal magnetoresistive (CMR) manganite La$_{2-2x}$Sr$_{1+2x}$Mn$_{2}$O$_{7, }$at the electronic doping levels of $x$=0.6 and $x$=0.67 respectively, have been proposed based on the \textit{in-situ} electron microscopic studies. In sharp contrast to the three-dimensional perovskite manganite, evidence of charge-ordered structures with bi-stripe models has been found. A new face-centered charge-ordered superstructure was observed at $x$=0.6. This structure is composed of bi-stripes of Mn$^{3+}$O$_{6}$ and paired Mn$^{4+}$O$_{6}$ rows alternatively stacking along the ordering direction, which is assembled from the building blocks of the charge-ordered phase at $x$=0.5. Taking into account of the systematic absence of reflections with the face-centered symmetry, its modulation vector was deduced as \textbf{q}=(1/10, 1/10, 0). Moreover, for another charge-ordered phase identified at $x$=0.67 with \textbf{q}=(1/6, 1/6, 0), again only the bi-stripe model fits the existing data over the Wigner-crystal model. [Preview Abstract] |
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AC.00003: Phase Identification for Cu-sheathed MgB$_{2}$ Superconducting wires Gan Liang, David Katz, Hui Fang, Kamel Salama, Zhongjia Tang X-ray diffraction (XRD) and SEM measurements have been performed for Cu-sheathed MgB$_{2 }$wires fabricated using ultra-fine Mg and B precursor and powder-in-tube method. Thirteen samples sintered at temperatures ranging from 450 \r{ }C to 875 \r{ }C, each for 5 minutes, were measured. It is found that MgB$_{2}$ phase can be formed in all these samples. From 400 \r{ }C to 550 \r{ }C, the fraction of the Mg$_{2}$Cu phase increases with sintering temperature while the Mg-phase decreases. Between 550 \r{ }C and 725 \r{ }C, the Mg$_{2}$Cu phase disappears, only MgB$_{2}$ and MgCu$_{2}$ phase co-exist. At or above 725 \r{ }C , MgB$_{2}$, MgB$_{4}$, and Mg$_{1+y}$Cu$_{32+\delta }$ phase coexist, and the fraction of the Mg$_{1+y}$Cu$_{32+\delta }$ phase increases with sintering temperature while the other two phases decrease. With the help of the measured XRD pattern for standard compound MgCu$_{2}$, the MgCu$_{2}$ phase in the Cu-sheathed MgB$_{2}$ wire samples can be clearly identified. We also for the first time identify a new phase, the Mg$_{1+y}$Cu$_{32+\delta }$ phase, in Cu-sheathed MgB$_{2}$ wires. The XRD results are analyzed together with SEM and current density ($J_{c})$ measurement results. [Preview Abstract] |
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AC.00004: AAPT - Calibration of a Radio Telescope Paul L. Fisher |
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AC.00005: AAPT - Einstein: His Predecessors and Successors Donald H. Kobe, Samuel E. Matteson AAPT abstract [Preview Abstract] |
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AC.00006: AAPT - QukckField Finite Element Method Software for Undergraduate Physics Education James R. Claycomb |
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AC.00007: AAPT - What is comPADRE? Using the AAPT's pre-college portion of the NSDL Project Cathy Mariotti Ezrailson, Bruce Mason, Thad Lurie AAPT abstract [Preview Abstract] |
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AC.00008: SPS - Electrochromic Blue Shift in Polymer Dispersed Liquid Crystal Cells Robert A. Ramsey, Suresh C. Sharma SPS abstract [Preview Abstract] |
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AC.00009: SPS - Hydrogen Spectroscopy of Hydrogen in Halfium Silcate Jose Martinez |
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AC.00010: SPS - Interplay of adsorbate ordering and step-step interactions on vicinal crystal surfaces Jennifer A. Zandstra, Michael J. Drake, Howard L. Richards SPS abstract [Preview Abstract] |
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AC.00011: SPS - Radio Interferometry of 1420 MHz at the Stephen F. Austin Observatory Andrew Wagers |
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