Bulletin of the American Physical Society
Spring 2012 Meeting of the APS Ohio-Region Section
Volume 57, Number 4
Friday–Saturday, April 13–14, 2012; Columbus, Ohio
Session C1: Poster Session (5:00-6:30PM) |
Hide Abstracts |
Chair: Gordon Aubrecht, Ohio State University Room: Physics Research Building Atrium |
|
C1.00001: On the Exact Solution Explaining the Accelerate Expanding Universe According to General Relativity Dmitri Rabounski A new method of calculation is applied to the frequency of a photon according to the travelled distance. It consists in solving the scalar geodesic equation (equation of energy) of the photon, and manifests gravitation, non-holonomity, and deformation of space as the intrinsic geometric factors affecting the photon's frequency. The solution obtained in the expanding space of Friedmann's metric manifests the exponential cosmological redshift: its magnitude increases, exponentially, with distance. This explains the accelerate expansion of the Universe registered recently by the astronomers. According to the obtained solution, the redshift reaches the ultimately high value $z \,{=}\, e^{\pi} \, {-}\, 1 \,{=}\, 22.14$ at the event horizon. The paper has been published in \textit{Progress in Physics}, 2012, v.2, L1--L6. [Preview Abstract] |
|
C1.00002: The effects of Improved Photometric Redshifts of Luminous Red Galaxies from SDSS in a Three-Point Galaxy Correlation Function Ashley Parker, Deborah Bard, Ann Bragg This research seeks to examine the implications of improved photometric redshift determinations when they are used in a three dimensional galaxy correlation function. We utilized the toolkit for multivariate analysis (TMVA) to determine photometric redshifts with improved accuracy for 45,399 Luminous Red Galaxies (LRG) from Data Release 8 (DR8) of the Sloan Digital Sky Survey (SDSS) with redshifts of $z < 0.87$ lying in a contiguous area of sky. The current SDSS photometric redshift determination method does not discriminate between blended and non-blended data when it determines the photometric redshift of a given galaxy. Considerably more accurate photometric redshift determinations were found, for the case of the blended and non-blended galaxies being treated separately. Photometric redshifts produced using this improved method are hypothesized to lead to increased accuracy of the galaxy correlation function. [Preview Abstract] |
|
C1.00003: Weakly driven, damped optomechanical cavity QED system Andrew Jacobs, James Clemens We investigate a weakly driven optical cavity containing a single two-level atom with an oscillating end mirror or a suspended dielectric membrane which is free to oscillate in response to radiation pressure. We calculate the probe spectrum and the photon and phonon statistics for the intracavity field and the oscillating mass with the optomechanical coupling treated quantum mechanically. [Preview Abstract] |
|
C1.00004: Epidemic spreading on scale-free networks with dynamic centrality Douglas Hoblet, Scott Hill Viruses have a vanishing epidemic threshold when they spread across a static scale-free network: in the thermodynamic limit, the virus will persist indefinitely on the network no matter how low its contagion rate. In this presentation, we explore the epidemic threshold of a virus on a dynamic scale-free network under the condition of \emph{dynamic centrality}, in which the virus is constrained to one of a rotating series of scale-free subnetworks with varying central ``hubs.'' Using simulations, we compare the epidemic threshold of the dynamic state to that of the static scale-free network as the network increases in size. [Preview Abstract] |
|
C1.00005: Monte Carlo simulations to investigate the response of RNA molecules to applied tension forces Dan Le, Jutta Luettmer-Strathmann In many viruses, genetic information is encoded in single-stranded ribonucleic acid (RNA) molecules. These molecules are very long chains with an interesting secondary structure that is still difficult to predict from the sequence of bases along the chain. In this work, we perform Monte Carlo Simulation of a simple model for RNA molecules under an applied tension force. We determine force-extension curves under equilibrium conditions for tension forces applied to different segments of the chain and investigate the relationship between the mechanical response and the secondary structure of the chain. [Preview Abstract] |
|
C1.00006: Brewster Angle Microscopy Study of Model Stratum Corneum Lipid Monolayers at the Air-Water Interface Ellen Adams, Alex Champagne, Joseph William, Heather Allen As the first and last barrier in the body, the stratum corneum (SC) is essential to life. Understanding the interactions and organization of lipids within the SC provides insight into essential physiological processes, including water loss prevention and the adsorption of substances from the environment. Langmuir monolayers have long been used to study complex systems, such as biological membranes and marine aerosols, due to their ability to shed light on intermolecular interactions. In this study, lipid mixtures with varying cholesterol and cerebroside ratios were investigated at the air/water interface. Surface tension measurements along with Brewster angle microscopy (BAM) images were used to examine the lipid phase transitions. Results indicate that cholesterol and cerebrosides form miscible monolayers, exhibiting ideal behavior. BAM images of a singular, uniform collapse phase also suggest formation of a miscible monolayer. [Preview Abstract] |
|
C1.00007: Interrogation of $Co_xZn_yNi_z Fe_2O_4$ ferrite nanoparticles for insight into specific power loss for medical hyperthermia Zafrullah Jagoo, Gregory Kozlowski, Zafer Turgut, Evgeny Rebrov Magnetic nanoparticles (MNPs) have shown to be viable candidates as heat sources for magnetic hyperthermia under an alternating magnetic field. The present work investigates heating characteristics of sol-gel processed ferro-magnetic $Co_xZn_yNi_zFe_2O_4$ (ferrite) nanoparticles with different magnetic properties. The nanoparticles were irradiated by a radio-frequency magnetic field through a 5-turns coil using a 1.2 kW heating system with variable frequency in the 295-315 kHz range and a maximum current output of 100 A. Higher specific power losses were measured for nanoparticles that had lower coercivities. The advantage of having a high specific power loss for clinical applications is that a minute amount of nanoparticle has to be introduced in the body to adequately destroy malignant tumor cells.\\[4pt] \begin{tabular}{|c|c|c|c|c|c|} \hline {Name} & {Grain Size} & {M$_r$} & {M$_s$} & {H$_c$} & {SPL$_{100A}$}\\ &(nm) & (emu/g) & (emu/g) & (Oe) & (W/g$^2$)\\ \hline Ni$_{0.5}$Zn$_{0.5}$Fe$_2$O$_4$ & 48.7 & 2.85 & 47.5 & 42.2 & 84 $\pm$ 2\\ Co$_{0.4}$Ni$_{0.4}$Zn$_{0.2}$Fe$_2$O$_4$ & 46 & 3.29 & 26.2 & 75.3 & 28 $\pm$ 3\\ NiFe$_2$O$_4$ & 42.9 & 3.47 & 14.8 & 146 & 17.0 $\pm$ 0.5\\ CoFe$_2$O$_4$ & 34.5 & 7.01 & 22.2 & 626 & 0.64 $\pm$ 0.05\\\hline \end{tabular} [Preview Abstract] |
|
C1.00008: Pulmonary surfactant and macrophages studied at the air/liquid interface revealed by Brewster angle microscopy (BAM) Dana-Marie Telesford, Heather Allen, Tracy Carlson, Larry Schlesinger The alveolus is lined with a complex mixture of lipids and proteins called pulmonary surfactant (PS) that lower surface tension at the alveolar air/liquid interface. The surface area of the lung for a 70 kg adult human at total lung capacity is $\sim $70 m$^{2}$. The large surface area and the direct exposure to the environment with every inhalation make this organ more susceptible to invasion by viruses, bacteria, and small particles. The most abundant cell recovered in human lung lavage is the alveolar macrophage which accounts for 85{\%} of the total. The primary function of the alveolar macrophage is to defend the lung against invasion, but also in the clearance of surfactant components in the lung. Quintero and Wright,$^{1}$ in an in vitro study observing alveolar macrophage metabolism of two lipid components dipalmitoyl phosphatidylglycerol (DPPG) and dipalmitoyl phosphatidylcholine (DPPC), noted that DPPG was removed at a faster rate. The mechanism by which this process takes place is not fully understood and our aim is to investigate the interactions of macrophages with different lipids using Brewster angle microscopy. Preliminary studies suggest that THP-1 differentiated macrophages do not significantly perturb DPPC and DPPG monolayers and research utilizing alveolar macrophages is underway. The effect of PS SP-A and SP-D is also discussed. [Preview Abstract] |
|
C1.00009: Macrophages interaction with pulmonary surfactant using coherent anti-Stokes Raman scattering (CARS) microscopy Minette Ocampo, Dana Marie Telesford, Heather Allen Alveolar pulmonary surfactant, composed mostly of phospholipids, is essential for maintenance of normal lung function. However, increased production of lung surfactant can lead to many pulmonary inflammatory disorders. Alveolar macrophages are responsible for the degradation of the surfactant and exhibit increased lipid uptake in inflamated lungs. Owing to their limited clearance capability, excessive accumulation of surfactant may impair their phagocytic function. In this study, the interaction of the macrophages with different lipid components was studied using coherent anti-Stokes Raman scattering (CARS) microscopy. CARS microscopy, a nonlinear vibrational technique which combines spectroscopy and microscopy, allows noninvasive characterization and imaging of chemical species without preparation or labeling. A monolayer of THP-1 macrophages and palmitic acid-d$_{31}$ on phosphate buffer solution was transferred to a coverslip using the Langmuir-Blodgett method and then imaged using CARS by mapping the CH$_{2}$ stretch signal of the lipid membrane of the macrophage and C-D stretch signal from palmitic acid-d$_{31}$. Preliminary results showed CARS images of the macrophage on the solid substrate and thermal degradation of the sample due to long exposure to high laser power. A contrast image is expected to be observed by mapping the CH$_{2}$ and C-D signals, which can show the lipid interaction and phagocytosis of the macrophage. [Preview Abstract] |
|
C1.00010: Interaction of Electric Fields with Vascular Cells Toloo Taghian, Abdul Sheikh, Daria Narmoneva, Andrei Kogan Electrical stimulation has been shown to be effective in improving healing rate of the non-healing or slow-healing wounds, a significant high-cost clinical issue. In order to optimize this process, identifying the mechanisms underlying the interaction of vascular cells with electric field (EF) is of interest. We have developed a 3D model of the cultured cells to simulate EF distribution in the cell membrane. The electrical stimulation of cells has been performed using our novel device that generates EF without any contact between electrodes and cells. The results indicate that cells respond to EF by releasing a specific growth factor (PlGF) which is important for blood vessel growth during wound healing. [Preview Abstract] |
|
C1.00011: Feasability of atomic identification of adsorbates with a scanning tunneling microscope XiaoYue Ni, Craig Howald A study of the feasibility of using a scanning tunneling microscope (STM) to detect differences between individual molecules or atoms adsorbed on a metal surface is reported. For a manageable model, the current through a one-dimensional metal-vacuum-metal junction is numerically simulated. The effect of an additional molecule on the sample is modeled as a modification of the vacuum potential barrier. Because the tunnel current is used to sense the distance to the sample, the value of the tunneling current has no absolute significance. Therefore we investigate how tunneling current varies with applied bias (tip-sample voltage) and with displacement of the tip relative to the sample for a given setpoint current at the largest applied bias. With varying strengths of the molecule's perturbation to the vacuum potential, maximum differences in tunneling currents are found. These can be compared to experimental noise in scanning tunneling microscope current to determine the smallest differences in potential that a given microscope can resolve. [Preview Abstract] |
|
C1.00012: Effects of Deposition Parameters on the Properties of Single Crystal ZnO Films Andrew Smith, Michael McMaster, Nagaraju Velpukonda, Joshua Petrus, Tom Oder We present the results from investigation of the effects of deposition parameters on the properties of sputter-deposited ZnO films. The films were deposited on sapphire substrates using radio frequency magnetron sputtering from a high purity ZnO solid target. Parameters investigated were the substrate temperature during deposition, which was varied from 25 \r{ }C to 600 \r{ }C; the deposition gas pressure varied from 5 mTorr to 40 mTorr and the gas flow rate varied from 5 to 30 standard cubic centimeter per minute (sccm). After post-deposition annealing in N$_{2}$ at 900 \r{ }C for 5 min, the films were characterized using photoluminescence spectroscopy, X-ray diffraction (XRD) and Atomic force microscopy measurements. The optimum conditions consisted of heating the sapphire substrates in O$_{2}$ prior to deposition, and depositing the film at a substrate temperature of 300 \r{ }C, a gas pressure of 10 mTorr and a gas flow rate of 20 sccm. The near band edge luminescence spectra had peaks with narrow line widths as small as 8.59 meV and are attributed to radiative recombination of bound excitons. The XRD 2$\theta $-scans had peaks at 34.4\r{ } with the best full-width-at-half-maximum value of 0.10\r{ }. [Preview Abstract] |
|
C1.00013: Picosecond transient Rayleigh scattering spectroscopy: probing band structure and carrier dynamics of single semiconductor nanowires Howard Jackson, Mohammad Montazeri, Aaron Wade, Melodie Fickensher, Leigh Smith, Jan Yarrison-Rice, Qian Gao, H. Tan, C. Jagadish We present picosecond pump-probe measurements of Rayleigh scattering from GaAs nanowires which show that these differential spectra are sensitive indicators of both the density and temperature of electron-hole pairs in a single nanowire. The probe pulse measures the change in the Rayleigh scattering as a function of time after excitation by the pump pulse. Because the Rayleigh scattered signal depends sensitively on both the real and imaginary parts of the dielectric response, these measurements provide direct insight into the nonlinear changes induced by both many body effects and state filling. Measurements on high quality single core-shell GaAs/AlGaAs nanowires were carried out at low temperature. Maps of the differential Rayleigh scattering spectra as a function of time are generated and interpreted using a semi-phenomenological model of these nonlinear effects. We show that both the photoexcited carrier density and the carrier temperature as a function of time can be directly obtained from the transient Rayleigh scattering data. [Preview Abstract] |
|
C1.00014: Conformation of a Lennard-Jones polymer in explicit solvent Yuting Ye, Mark Taylor The conformation of a polymer chain is solution is coupled to the local structure of the surrounding solvent and can undergo large changes in response to variations in solvent density and temperature. The many-body effects of solvent on the structure of an n-mer chain can be formally mapped to an exact n-body solvation potential. These potentials map the chain-solvent system to a single chain, thereby dramatically reducing the computational complexity of the polymer chain-in-solvent problem. We have recently shown that a pair-decomposition of this n-body potential is valid for short Lennard-Jones (LJ) chains in explicit LJ solvent [1]. Here we use these short chain results to construct solvation potentials for long chains. We present results for the size and intramolecular structure of LJ chains up to length n=400 in LJ solvent at state points spanning the solvent phase diagram (including vapor, liquid, and super-critical regions). In comparison with simulation results for the corresponding full chain-in-solvent system, our solvation potential approach is found to be quantitatively accurate for a wide range of solvent conditions and chain lengths.\\[4pt] [1] M.P. Taylor and S.R. Adhikari, J. Chem. Phys. 135, 044903 (2011). [Preview Abstract] |
|
C1.00015: Electrochemical analysis of hydrogen equilibrium near the inversion temperature Daniel Warren, Craig Howald In this work we examine the non-ideality of the equilibrium between dissolved hydrogen ions and molecular hydrogen gas through a temperature range spanning the maximum inversion temperature of hydrogen. A pressure cell with a methanol solution, an aluminum electrode, and a platinum electrode is used to measure the approach to equilibrium. This is accomplished by simultaneously monitoring current flow between the electrodes and pressure changes for varying driving potentials as a function of temperature. [Preview Abstract] |
|
C1.00016: Preliminary Investigations of Wind Potential at Marietta College William Vance, Dennis Kuhl Marietta College received a grant to build a wind turbine on campus for educational purposes, as a demonstration of alternative energy production, and to promote new energy systems minors. We report on an investigation of the potential wind energy profile on Marietta College's campus and preliminary wind tunnel studies of variations in shroud design for a shrouded horizontal axis wind turbine. Anemometers were placed in three locations on the campus and wind velocity data was logged for several months. The data provides average wind speeds as well as prevailing wind directions. A wind tunnel was constructed to test shrouded wind turbines. A shrouded wind turbine with a diffuser and flange can maximize the wind speed through a turbine, thus maximizing its power output. This paper sets the stage for future projects to further develop the turbine models' geometry that will maximize power output. [Preview Abstract] |
|
C1.00017: Partition function zeros and phase transitions of a square-well polymer Pyie Phyo Aung, Taylor Mark The zeros of the canonical partition functions for flexible square-well polymer chains have been computed for chains up to length 256 for a range of square-well diameters. We have previously shown that such chain molecules can undergo a coil-globule and globule-crystal transition as well as a direct coil-crystal transition [1]. Here we show that each of these transitions has a well-defined signature in the complex-plane map of the partition function zeros. The freezing transitions are characterized by nearly circular rings of uniformly spaced roots, indicative of a discontinuous transition. The collapse transition is signaled by the coalescence of roots onto an elliptical horse-shoe segment pinching down towards the positive real axis. For sufficiently small square-well diameter the elliptical collapse ring merges with the circular freezing ring yielding the direct coil-crystal transition. The root density of all rings increases with increasing chain length and the leading roots move towards the positive real axis, implying a divergence of the specific heat in the thermodynamic limit (as originally proposed by Yang and Lee).\\[4pt] [1] M.P. Taylor, W. Paul, and K. Binder, J. Chem. Phys. \textbf{131}, 114907 (2009). [Preview Abstract] |
|
C1.00018: Helping teachers in middle and high school to do self-evaluations of teaching Jennifer Esswein, Gordon Aubrecht, Bill Schmitt Formative assessments can allow teachers to immediately understand what is and is not working in their classrooms for the purpose of changing how they teach various content. We encouraged teachers who are participating in a project funded through the Ohio Department of Education to do real formative assessments as an application for the development of formative assessments in the classroom in a rurally located, city high-needs district in the state of Ohio. The authors wrote formative assessments (CFAs) for the teachers in differing categories. Teachers had the opportunity to provide feedback, the CFAs were changed if necessary, and then they analyzed the CFA at the both the beginning and the end of the quarter. The emphasis in the analysis was on what student thinking as expressed in writing reveals. The pretests reveal what students think at the beginning, giving the teacher an idea of what ideas might already exist, right or wrong; the posttest should reveal to the teacher whether the instruction succeeded. The final quarter of the year, we asked the teachers themselves to draft assessments for their classes. Results indicate changes not only in the way teachers view their pedagogical approaches, but also in how teachers consider student personal epistemologies. [Preview Abstract] |
|
C1.00019: Local structure in hard-sphere chain-molecule fluids Sambid Wasti, Mark Taylor The conformation of a polymer chain in solvent is coupled to the local structure of the solvent environment. For hard-sphere systems, a monomeric solvent acts to compress a flexible hard-sphere-solute chain and, for a dense system, the local solvent structure is imprinted onto the chain. Here we use Monte Carlo simulation, including bond-rebridging moves, to study the size and conformation of a hard sphere chain in a hard-sphere solvent as a function of both solvent density and solvent diameter. We also study the structure of a hard-sphere-chain solute in a hard-sphere-chain solvent. In the case of a 5-mer chain in 5-mer solvent we show that the effects of solvent can be mapped to a set of two-body solvation potentials. Following our previous work on hard-sphere chains in monomeric solvent [1], we explore the application of these short chain potentials to the study of longer chain-molecule fluids. \\[4pt] [1] M.P. Taylor and S. Ichida, J. Polym. Sci. B: Polym. Phys. 45, 3319 (2007). [Preview Abstract] |
|
C1.00020: Longitudinal Waves in Strongly Coupled Two-ring Dust Chains W.L. Theisen, T.E. Sheridan A strongly coupled two-ring dust chain of micron sized particles is created experimentally in an R-F generated plasma. The two rings with different radii are confined in a circular potential well and longitudinal dust lattice waves are transmitted along the chain. The dispersion relation is measured and compared to theory. [Preview Abstract] |
|
C1.00021: Two-dimensional diffusion in a self-heated dusty plasma Donald J. Pleshinger, T.E. Sheridan We investigate self diffusion in a dusty plasma using the Dusty Ohio Northern University experimenT (DONUT). A two-dimensional liquid of about 100 dust particles is formed at the center of, and heated by, a toroidal gas of dust particles confined in the surrounding annular potential well. The motions of individual dust particles are recorded, allowing particle trajectories to be directly observed. The mean-squared displacement is found to increase linearly with time, in agreement with diffusion theory. Dependence of the diffusion coefficients and probability distribution functions on temperature will be presented. [Preview Abstract] |
|
C1.00022: Configuration phase transitions in small Debye clusters T.E. Sheridan We consider the configuration phases of a dusty plasma consisting of $n \le 10$ identical particles confined in a two-dimensional biharmonic well. The ground state configuration depends on three parameters: $n$, the Debye screening parameter $\kappa$ and the well anisotropy $\alpha^2$. Changes in any of these parameters are predicted to cause continuous or discontinuous transitions between qualitatively distinct ground state configurations. We have experimentally measured ground state configurations as the well anisotropy is varied. Both continuous and discontinuous structure transitions are observed. Experimental results show good agreement with model predictions. [Preview Abstract] |
|
C1.00023: Modeling of the photonic crystal waveguide modes with the FDTD method Buddhi Rai The electromagnetic modes are investigated using a simple 1D implementation of the FDTD numerical algorithm to a model of 1D photonic crystal (layered media). The fields $E_{z}$ and $H_{y}$ are simulated along the $\hat x$-axis, the propagation direction. Source implementation and the effects of various boundary conditions such as ABC, Mur on TF/SF fields are investigated. Of particular focus in this paper is, for example, on investigating the guided and/or radiation modes at a stop band frequency of the photonic crystal formed of linear and Kerr nonlinear media. Such structures exhibit interesting transmission and reflection properties that make them suitable for optical devices with frequency/wavelength tunable characteristics. [Preview Abstract] |
|
C1.00024: Femur bone strength in \textit{Tyrannosaurus rex}: A study of sexual dimorphism Scott Lee \textit{Tyrannosaurus rex} is the iconic species of a fearsome predator and is held in fascination by virtually everyone. Like many other species, \textit{Tyrannosaurs rex} displayed sexual dimorphism with the females larger than the males. The femur bones of 14 fossil specimens were examined to determine if the maximum running abilities were significantly different for the two genders. No significant difference is observed. [Preview Abstract] |
|
C1.00025: Parameterized Special Theory of Relativity Florentin Smarandache We have parameterized Einstein's thought experiment with atomic clocks, supposing that we know neither if the space and time are relative or absolute, nor if the speed of light is ultimate speed or not. We have obtain a Parameterized Special Theory of Relativity (1982). Our PSTR generalized not only Einstein's Special Theory of Relativity (1905), but also our \underline {Absolute Theory of Relativity} (1982), and has introduced \underline {three more possible Relativities} (1982) to be studied in the future. Afterwards, we extended our research considering not only constant velocities but constant accelerations too. [Preview Abstract] |
Follow Us |
Engage
Become an APS Member |
My APS
Renew Membership |
Information for |
About APSThe American Physical Society (APS) is a non-profit membership organization working to advance the knowledge of physics. |
© 2024 American Physical Society
| All rights reserved | Terms of Use
| Contact Us
Headquarters
1 Physics Ellipse, College Park, MD 20740-3844
(301) 209-3200
Editorial Office
100 Motor Pkwy, Suite 110, Hauppauge, NY 11788
(631) 591-4000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 20045-2001
(202) 662-8700