# Physics Commons™

Articles 1 - 30 of 300

## Full-Text Articles in Physics

Giant Suppression Of Flux-Flow Resistivity In Heavy-Ion Irradiated Tl2Ba2Ca2Cu3O10 Films: Influence Of Linear Defects On Vortex Transport, R.C. Budhani, M. Suenaga, Sy_Hwang Liou Dec 1992

#### Giant Suppression Of Flux-Flow Resistivity In Heavy-Ion Irradiated Tl2Ba2Ca2Cu3O10 Films: Influence Of Linear Defects On Vortex Transport, R.C. Budhani, M. Suenaga, Sy_Hwang Liou

##### Si-Hwang Liou Publications

A large shift of the onset of flux-flow resistivity and the irreversibility line Hirr (T) to higher temperatures is observed in Tl2Ba2Ca2Cu3O10 films containing linear defects created by Ag+21 ion irradiation. The Hirr(T), which has a characteristic ssL shape in highly anisotropic Tl and Bi based cuprates, becomes more like that of YBa2Cu3O7 in the presence of these defects. The Jc at 77 K also shows a large increase as a result of flux localization at the defects. The transport data ...

The Elastic Moduli Of Simple Two-Dimensional Isotropic Composites: Computer Simulation And Effective Medium Theory, K. A. Snyder, E. J. Garboczi, Anthony Roy Day Dec 1992

#### The Elastic Moduli Of Simple Two-Dimensional Isotropic Composites: Computer Simulation And Effective Medium Theory, K. A. Snyder, E. J. Garboczi, Anthony Roy Day

##### Anthony Roy Day

An algorithm, combining digital-image with spring network techniques, has been developed that enables computation of the elastic moduli of random two-dimensional multiphase composites. This algorithm is used to study the case of isotropic, randomly centered, overlapping circular inclusions in an isotropic elastic matrix. The results of the algorithm for the few-inclusion limit, as well as the case where both phases have the same shear moduli, agree well with the exact results for these two problems. The case where the two phases have the same Poisson’s ratio, but different Young’s moduli, is also studied, and it is shown that ...

The Weakest Bond: Experimental Observation Of Helium Dimer, Fei Luo, George C. Mcbane, Geunsik Kim, Clayton F. Giese, W. Ronald Gentry Dec 1992

#### The Weakest Bond: Experimental Observation Of Helium Dimer, Fei Luo, George C. Mcbane, Geunsik Kim, Clayton F. Giese, W. Ronald Gentry

##### Peer Reviewed Articles

Helium dimer ion was observed after electron impact ionization of a supersonic expansion of helium with translational temperature near 1 mK. The dependence of the ion signal on source pressure, distance from the source, and electron kinetic energy was measured. The signal was determined to arise from ionization of neutral helium dimer.

Translational Correlations In The Vortex Array At The Surface Of A Type-Ii Superconductor, M. Cristina Marchetti, David R. Nelson Dec 1992

#### Translational Correlations In The Vortex Array At The Surface Of A Type-Ii Superconductor, M. Cristina Marchetti, David R. Nelson

##### Physics

We discuss the statistical mechanics of magnetic flux lines in a finite-thickness slab of type-II superconductor. The long wavelength properties of a flux-line liquid in a slab geometry are described by a hydrodynamic free energy that incorporates the boundary conditions on the flux lines at the sample's surface as a surface contribution to the free energy. Bulk and surface weak disorder are modeled via Gaussian impurity potentials. This free energy is used to evaluate the two-dimensional structure factor of the flux-line tips at the sample surface. We find that surface interaction always dominates in determining the decay of translational ...

Rigid Chiral Membranes, Philip C. Nelson, Thomas Powers Dec 1992

#### Rigid Chiral Membranes, Philip C. Nelson, Thomas Powers

##### Department of Physics Papers

Statistical ensembles of ﬂexible two-dimensional ﬂuid membranes arise naturally in the description of many physical systems. Typically one encounters such systems in a regime of low tension but high stiﬀness against bending, which is just the opposite of the regime described by the Polyakov string. We study a class of couplings between membrane shape and in-plane order which break 3-space parity invariance. Remarkably there is only one
such allowed coupling (up to boundary terms); this term will be present for any lipid bilayer composed of tilted chiral molecules. We calculate the renormalization-group behavior of this relevant coupling in a simpliﬁed ...

Explosion Of A Liquid Film In Contact With A Pulse-Heated Solid Surface Detected By The Probe-Beam Deflection Method, P.T. Leung, Andrew C. Tam, Nhan Do, Leander Klees, Wing P. Leung Dec 1992

#### Explosion Of A Liquid Film In Contact With A Pulse-Heated Solid Surface Detected By The Probe-Beam Deflection Method, P.T. Leung, Andrew C. Tam, Nhan Do, Leander Klees, Wing P. Leung

##### Physics Faculty Publications and Presentations

The threshold for explosive vaporization of a liquid layer on an opaque solid surface heated by an ultraviolet excimer pulsed laser is studied by a photoacoustic probe-beam deflection method. The probe beam traverses the liquid in the vicinity of the laser-heated liquid-solid interface. Below the explosion threshold, photoacoustic generation in the solid occurs only through a thermoelastic mechanism, which results mainly in shear waves that do not couple well into the liquid. Above the explosion threshold, photoacoustic pulses in the solid are also produced by explosive recoil, hence producing longitudinal pulses in the solid that couple well into the liquid ...

Calculation Of The Residual Resistivity And The Thermoelectric Power Of Sp Impurities In Silver, Thomas Vojta, Ingrid Mertig, Rudolf Zeller Dec 1992

#### Calculation Of The Residual Resistivity And The Thermoelectric Power Of Sp Impurities In Silver, Thomas Vojta, Ingrid Mertig, Rudolf Zeller

##### Physics Faculty Research & Creative Works

We present ab initio calculations for the residual resistivity and the thermopower of sp impurities in silver. The calculations are based on density-functional theory and the Korringa-Kohn-Rostoker Greens-function method. The linearized Boltzmann equation is solved by means of a Fermi-surface harmonic expansion to calculate the residual resistivity, taking into account the anisotropic electronic properties of the dilute alloy. The thermoelectric power was obtained from the energy dependence of the residual resistivity by means of Mott's formula. The results are in satisfying agreement with highly precise experimental results and confirm experimentally obtained deviations from a quadratic dependence on the valence ...

Intrinsic Loss In Infrared Optical Fibers, Prapassorn Tantiphanwadi Dec 1992

#### Intrinsic Loss In Infrared Optical Fibers, Prapassorn Tantiphanwadi

##### All Graduate Theses and Dissertations

Recently, in communication system, fiber optics has become a most interesting development tool as a transmission medium. It first appeared as a feasible transmission medium in 1970. The reason for the development in fiber optics comes from the overwhelming advantage in technology and economy compared to wires and coaxial links. For technology progress, typically, optical fiber has a wide transmission band-width (0.1-1000 GHz), lower loss per unit length (0.15 – 5 dB km ^-1[1]), and does not allow electromagnetic interference. For example, signal transmitted over commercial silica-based fiber must be reamplified every 10 to 50 kilometers, whereas signals ...

Measurements Of Νw2 And R=Σl/Σt From Inelastic Electron-Aluminum Scattering Near X=1, P E. Bosted, A Lung, L Andivahis, L M. Stuart, J Alster, R G. Arnold, C C. Chang, F S. Dietrich, W Dodge, R Gearhart, J Gomez, K A. Griffioen, R S. Hicks, C E. Hyde-Wright, C Keppel, S E. Kuhn, J Lichtenstadt, R A. Miskimen, Gerald Alvin Peterson Nov 1992

#### Measurements Of Νw2 And R=Σl/Σt From Inelastic Electron-Aluminum Scattering Near X=1, P E. Bosted, A Lung, L Andivahis, L M. Stuart, J Alster, R G. Arnold, C C. Chang, F S. Dietrich, W Dodge, R Gearhart, J Gomez, K A. Griffioen, R S. Hicks, C E. Hyde-Wright, C Keppel, S E. Kuhn, J Lichtenstadt, R A. Miskimen, Gerald Alvin Peterson

##### Gerald Alvin Peterson

Cross sections for inclusive electron scattering from aluminum have been measured at both forward and backward angles in the kinematic region near x =1 and 1.75 & Q & 7 (GeV/c) . The forward-angle data are in good agreement with a recent calculation. Both the data and the calculation show scaling behavior for F2(g, Q~)=vs(g, Q2) at high Q for fixed values of the Nachtmann variable g. The ratio R =oL /trr has been extracted for 1.75 &Q &5 (GeV/c) and is found to decrease with Q2 to a value consistent with zero at the highest ...

Vibrational Excitations In Percolation: Localization And Multifractality, Armin Bunde, H. Eduardo Roman, Stefanie Russ, Amnon Aharony, A. Brooks Harris Nov 1992

#### Vibrational Excitations In Percolation: Localization And Multifractality, Armin Bunde, H. Eduardo Roman, Stefanie Russ, Amnon Aharony, A. Brooks Harris

##### Department of Physics Papers

We discuss localized excitations on the incipient infinite percolation cluster. Assuming a simple exponential decay of the amplitudes ψi in terms of the chemical (minimal) path, we show theoretically that the ψ’s are characterized by a logarithmically broad distribution, and display multifractal features as a function of the Euclidean distance. The moments of ψi exhibit novel crossover phenomena. Our numerical simulations of fractons exhibit a nontrivial distribution of localization lengths, even when the chemical distance is fixed. These results are explained via a generalization of the theory.

Modeling Sio Maser Emission From Late-Type Stars, Philip B. Lockett, Moshe Elitzur Nov 1992

#### Modeling Sio Maser Emission From Late-Type Stars, Philip B. Lockett, Moshe Elitzur

##### Physics and Astronomy Faculty Publications

We have performed a thorough study of both radiative and collisional pumping of the SiO masers around late-type stars, carefully considering the combined and separate actions of each type of pump in order to gauge its effectiveness. We find that collisional pumping is severely underestimated when the model calculations use a small number (less than about 18) of rotational levels in each vibrational state. We have developed a procedure that corrects this problem and gives results that are nearly independent of the number of levels utilized in the calculations. We recognize, but do not solve, an important problem that afflicts ...

Non-Relativistic Qcd For Heavy Quark Systems, Simon Catterall, F. R. Devlin, I. T. Drummond, R. R. Horgan, A. D. Simpson Nov 1992

#### Non-Relativistic Qcd For Heavy Quark Systems, Simon Catterall, F. R. Devlin, I. T. Drummond, R. R. Horgan, A. D. Simpson

##### Physics

We employ a nonrelativistic version of QCD (NRQCD) to study heavy quark-antiquark bound states in the lowest approximation without fine structure. We use gluon configurations on a 16^3 by 48 lattice at beta=6.2 from the UKQCD collaboration. For quark masses in the vicinity of the b we obtain bound state masses for S, P and both types of D wave. We also detect signals for two types of hybrids (quark,antiquark,gluon states). The results are sufficiently accurate to confirm that the values of the D wave mass from both lattice D waves coincide indicating that the ...

Characterization Of Boron Carbide Thin Films Fabricated By Plasma Enhanced Chemical Vapor Deposition From Boranes, Sunwoo Lee, John Mazurowski, G. Ramseyer, Peter A. Dowben Nov 1992

#### Characterization Of Boron Carbide Thin Films Fabricated By Plasma Enhanced Chemical Vapor Deposition From Boranes, Sunwoo Lee, John Mazurowski, G. Ramseyer, Peter A. Dowben

##### Peter Dowben Publications

We have fabricated boron carbide thin films on Si(111) and other substrates by plasma-enhanced chemical-vapor deposition (PECVD). The PECVD of boron carbides from nido-cage boranes, specially nido-pentaborane(9) (B5H9), and methane ( CH4) is demonstrated. The band gap is closely correlated with the boron to carbon ratio and can range from 0.77 to 1.80 eV and is consistent with the thermal activation barrier of 1.25 eV for conductivity. We have made boron carbide by PECVD from pentaborane and methane that is sufficiently isotropic to obtain resistivities as large as 1010 ...

Novel Results For Quasiclassical Linear Transport In Metallic Multilayers, Horacio E. Camblong Nov 1992

#### Novel Results For Quasiclassical Linear Transport In Metallic Multilayers, Horacio E. Camblong

##### Physics and Astronomy

We analyze the linear transport behavior of metallic multilayers via the Kubo formula for a Hamiltonian with zero-range spin-dependent potentials. We find a direct connection between the Boltzmann and the Kubo approaches. Our two-point transport theory validates the quasiclassical approach for multilayered structures and introduces a new treatment of interfaces via angle-dependent coherent transmission coefficients.

Direct Picosecond Measurement Of Photoinduced Cooper Pair Breaking In Lead, John F. Federici, Benjamin I. Greene, Peter N. Saeta, Douglas R. Dykaar, F. Sharifi, R. C. Dynes Nov 1992

#### Direct Picosecond Measurement Of Photoinduced Cooper Pair Breaking In Lead, John F. Federici, Benjamin I. Greene, Peter N. Saeta, Douglas R. Dykaar, F. Sharifi, R. C. Dynes

##### All HMC Faculty Publications and Research

We report on a direct kinetic measurement of Cooper-pair breaking in superconducting lead. A 100-fs pulse of visible light was used to excite a thin-film lead sample, while the Cooper-pair density was optically probed using an ultrashort pulse of broadband far-infrared radiation. Subsequent to the absorption of the visible light, a rapid (ps) change in the far-infrared optical transmission was observed, corresponding to the breaking of Cooper pairs and the collapse of the superconducting gap.

Analysis Of Several Modified Webb Type Models Of Chemotherapy Treatment, Philip Edward Patterson Nov 1992

#### Analysis Of Several Modified Webb Type Models Of Chemotherapy Treatment, Philip Edward Patterson

##### ETD Collection for AUC Robert W. Woodruff Library

We consider modified versions of a cell population model for periodic chemotherapy treatment of tumors. These models contain both proliferating and quiescent cells, and treats the transitions between the two types of cells. Our models are defined by replacing the loss term function, μ(t, c), in Webb's model by a constant. This corresponds to having a constant infusion of the drug rather than having a periodic chemotherapy treatment. We compare our results with those of Webb who shows that shorter periods of treatment are advantageous.

Renormalization-Group Study Of The Standard Model And Its Extensions: The Standard Model, H. Arason, Diego Castano, B. Kesthelyi, S. Mikaelian, E. J. Piard, P. Ramond, B. D. Wright Nov 1992

#### Renormalization-Group Study Of The Standard Model And Its Extensions: The Standard Model, H. Arason, Diego Castano, B. Kesthelyi, S. Mikaelian, E. J. Piard, P. Ramond, B. D. Wright

##### Chemistry and Physics Faculty Articles

In this paper we present a comprehensive analysis of the running of all the couplings of the standard model to two loops, including threshold effects. Our purpose is twofold—to determine what the running of these parameters may indicate for the physics of the standard model and to provide a template for the study of its extensions up to the Planck mass.

Katz Model Prediction Of Caenorhabditis Elegans Mutagenesis On Sts-42, Francis A. Cucinotta, John W. Wilson, Robert Katz, Gautam Badhwar Nov 1992

#### Katz Model Prediction Of Caenorhabditis Elegans Mutagenesis On Sts-42, Francis A. Cucinotta, John W. Wilson, Robert Katz, Gautam Badhwar

##### Robert Katz Publications

The Katz track structure model has been applied to describe recessive lethal mutagenesis in the nematode Caenorhabditis elegans after exposure to heavy ions. Based on models of the cosmic-ray environment and heavy-ion transport, mutation rates for the International Microgravity Laboratory 1 (IML-1) experiment on the Space Transportation System 42 (STS-42) are predicted and the results are discussed.

A Technique For The Evaluation Of Double Excitation Of Atoms By Fast Protons And Antiprotons, Jack C. Straton, James H. Mcguire, Zheng Chen Nov 1992

#### A Technique For The Evaluation Of Double Excitation Of Atoms By Fast Protons And Antiprotons, Jack C. Straton, James H. Mcguire, Zheng Chen

##### Physics Faculty Publications and Presentations

A technique for evaluating cross sections for two-electron excitation in collisions of atoms with fast particles of charge ZP is presented. The atomic wave function is approximated by a sum of pair products of one-electron wave functions, with the coefficients chosen by diagonalizing the fully correlated twoelectron Hamiltonian. Thus spatial correlation is included in both the asymptotic and scattering regions by using these configuration-interaction (Cl) wave functions for initial, intermediate, and final states. Use of CI wave function also allows the first-order contributions to be expressed in closed, analytical form. Both the energy-conserving and energy-nonconserving parts of the second-order amplitude ...

A Mössbauer Effect Study Of The Microscopic Magnetic Properties Of Nd2Fe17 And Nd2Fe17N2.6, Gary J. Long, Oran Allan Pringle, Fernande Grandjean, K. H. J. Buschow Nov 1992

#### A Mössbauer Effect Study Of The Microscopic Magnetic Properties Of Nd2Fe17 And Nd2Fe17N2.6, Gary J. Long, Oran Allan Pringle, Fernande Grandjean, K. H. J. Buschow

##### Chemistry Faculty Research & Creative Works

The Mössbauer spectra of Nd2Fe17 and Nd 2Fe17N2.6 have been measured at various temperatures between 78 and 295 K and analyzed with a model that is based on the Wigner-Seitz cell environment of each iron site, the orientation of the magnetization, and the magnetic moments as determined from either neutron-diffraction measurements or band-structure calculations. Upon nitrogenation of Nd2Fe17, the weighted average isomer shift increases from 0.060 to 0.164 mm/s and further the isomer shifts of the four crystallographically distinct sites increase in agreement with the increase ...

Exact Enumeration And Scaling For Fragmentation Of Percolation Clusters, Boyd F. Edwards, M. F. Gyure, M. V. Ferer Nov 1992

#### Exact Enumeration And Scaling For Fragmentation Of Percolation Clusters, Boyd F. Edwards, M. F. Gyure, M. V. Ferer

##### All Physics Faculty Publications

The fragmentation properties of percolation clusters yield information about their structure. Monte Carlo simulations and exact cluster enumeration for a square bond lattice and exact calculations for the Bethe lattice are used to study the fragmentation probability as(p) of clusters of mass s at an occupation probability p and the likelihood bs′s(p) that fragmentation of an s cluster will result in a daughter cluster of mass s′. Evidence is presented to support the scaling laws as(pc)∼s and bs′s(pc)=sg(s′/s), with φ=2-σ given ...

Linear Theory Of Non-Neutral Plasma Equilibrium In A Tilted Magnetic Field, Ross L. Spencer, Grant W. Hart Nov 1992

#### Linear Theory Of Non-Neutral Plasma Equilibrium In A Tilted Magnetic Field, Ross L. Spencer, Grant W. Hart

##### Faculty Publications

A linear perturbation expansion has been found that allows the rapid and accurate calculation of the response of a non-neutral plasma to a tilted magnetic field. The results of the calculation have been found to agree with previous three-dimensional equilibrium calculations, and also to agree with Keinigs' [Phys. Fluids 24, 860 (1981)] calculation of zero-frequency resonances caused by magnetic field errors. This expansion also allows the perturbed velocity to be calculated. It is speculated that this perturbed flow may be related to the enhanced radial transport in a non-neutral plasma with a tilted magnetic field.

Variationally Stable Treatment Of Two- And Three-Photon Detachment Of H- Including Electron-Correlation Effects, Chih-Ray Liu, Bo Gao, Anthony F. Starace Nov 1992

#### Variationally Stable Treatment Of Two- And Three-Photon Detachment Of H- Including Electron-Correlation Effects, Chih-Ray Liu, Bo Gao, Anthony F. Starace

##### Anthony F. Starace Publications

A variationally stable, adiabatic hyperspherical treatment of two- and three-photon detachment of H- is presented. Results are compared with analytic predictions of a zero-range potential model of H-. Detailed comparisions are made also with other theoretical results which include the effects of electron correlations. We predict analytically (and demonstrate numerically) an extreme sensitivity of the theoretical predictions to any errors in the value of the electron affinity employed. In an Appendix we show that the low-intensity limit of the Keldysh treatment [Sov. Phys. JETP 20, 1307 (1965)] of detachment of an electron bound in a zero-range potential agrees with the ...

#### Quantitative Measurement Of Pyrolysis And Combustion Species Concentration By Molecular-Beam-Sampling-Mass-Spectrometry, Xian Zhong

##### Theses

A molecular-beam-sampling apparatus utilizing both a time-of-flight mass spectrometer with vacuum ultraviolet (VUV) photoionization and a quadrupole mass spectrometer with electron impact ionization is described. These systems are used to analyze reactants and products, as well as reactive intermediates, from flow tube experiments at reduced pressures and elevated temperatures. It is shown that the quadrupole signal sensitivity can be predicted using literature cross sections which are based upon the atom hybridization within the various molecules. Measurements of the VUV photoionization sensitivity for stable species led to development of a group additivity approach to predict cross sections. This approach was extended ...

Use Of Raman Spectroscopy In Characterizing Soft X-Ray Multilayers: Tools In Understanding Structure And Interfaces, Ming Cai, Qi Wang, David D. Allred, Larry V. Knight, Dorian M. Hatch, A. Reyes-Mena, Guizhong Zhang Oct 1992

#### Use Of Raman Spectroscopy In Characterizing Soft X-Ray Multilayers: Tools In Understanding Structure And Interfaces, Ming Cai, Qi Wang, David D. Allred, Larry V. Knight, Dorian M. Hatch, A. Reyes-Mena, Guizhong Zhang

##### Faculty Publications

Our group is studying the structure and interfaces of soft x-ray multilayers by various techniques including x-ray diffraction and Raman spectroscopy. Raman spectroscopy is particularly useful since it is sensitive to the identity of individual bonds and thus can potentially characterize the abruptness of interfaces in multilayers. Blocking interfacial mixing is very important in achieving and maintaining high reflectivity. We report our studies of the as-deposited and postannealed structure of Mo/Si and W/C multilayers. The Mo/Si system is probably the most widely studied multilayer currently because of its potential applications for soft x-ray projection lithography for the ...

Haze-Free Polymer Dispersed Liquid-Crystals Utilizing Linear Polarizers, John L. West, David S. Fredley, J. Craig Carrell Oct 1992

#### Haze-Free Polymer Dispersed Liquid-Crystals Utilizing Linear Polarizers, John L. West, David S. Fredley, J. Craig Carrell

##### Chemistry & Biochemistry Publications

Polymer dispersed liquid crystal(PDLC) light shutters are scattering in the OFF state and transparent in the ON state for normally incident light. PDLC shutters appear hazy in the ON state when viewed at oblique angles as a result of light scattering. The haze is caused by the effective increase in the refractive index of the liquid crystal. However, only one polarization of the incident radiation is scattered. Therefore, PDLC shutters with a linearly polarized sheet on the incident surface are haze‐free for an entire viewing plane. While addition of a polarizer reduces transmission through the PDLC to less ...

Symmetry Breaking In A Generalized Skyrme Model, Joseph Schechter Oct 1992

#### Symmetry Breaking In A Generalized Skyrme Model, Joseph Schechter

##### Physics

We first outline the calculations of the neutron-proton mass difference and of the axial singlet matrix element (relevant to the "proton spin" puzzle) in a generalized Skyrme model of pseudoscalars and vectors. These two calculations are, perhaps surprisingly, linked to each other and furthermore are sensitive to some fine details of symmetry breaking in the effective meson Lagrangian. This provides a motivation for us to examine these symmetry breaking terms more closely. We find a qualitatively new feature in the symmetry breaking pattern of the vector meson system and discuss its significance. (Talk at Workshop on "Baryons as Skyrme Solitons ...

Effective Hadron Dynamics: From Meson Masses To The Proton Spin Puzzle, Joseph Schechter, A Subbaraman, H. Weigel Oct 1992

#### Effective Hadron Dynamics: From Meson Masses To The Proton Spin Puzzle, Joseph Schechter, A Subbaraman, H. Weigel

##### Physics

We construct a three flavor chiral Lagrangian of pseudoscalars and vectors with special emphasis on the symmetry breaking terms. Comparing tree level two and three point functions with experiment allows us to first, fix the parameters of the model (including the light quark mass ratios) and second, to predict m(K^{*+})-m(K^{*\circ}),\, \Gamma(K^*\rightarrow K\pi) and \Gamma(\phi\rightarrow K {\overline K}). The last mentioned quantities come out reasonably well, in contrast to an ordinary" SU(3) treatment. For this purpose we need second order" symmetry breakers involving the vector fields analogous to those needed for ...

Stars Classified As Constant In The General Catalog Of Variable Stars, Edward G. Schmidt, John R. Chab, Darwin E. Reiswig Oct 1992

#### Stars Classified As Constant In The General Catalog Of Variable Stars, Edward G. Schmidt, John R. Chab, Darwin E. Reiswig

##### Edward Schmidt Publications

Photometric observations have been made of 16 stars classified as constant, CST or CST:, in the General Catalog of Variable Stars. One star, U Tauri, was found to be a rapid irregular variable and three others may vary at a low level. In two cases, FV Delphini and FP Geminorum, the star identified as the variable on published finding charts is not variable but a nearby star did vary. It is suggested that the wrong stars were marked on the charts but the possibility remains that the variables may have exhibited constancy during earlier observations.

Interaction Of Profiled Light With Contrapropagating Acoustic Waves: Fourier Transform Approach, Partha P. Banerjee, Chen-Wen Tarn, Jaw-Jueh Liu Oct 1992

#### Interaction Of Profiled Light With Contrapropagating Acoustic Waves: Fourier Transform Approach, Partha P. Banerjee, Chen-Wen Tarn, Jaw-Jueh Liu

##### Electrical and Computer Engineering Faculty Publications

A straightforward Fourier-transform approach is employed to investigate acousto-optic interaction between an input optical beam with arbitrary profile and contrapropagating cw sound in the Bragg regime. The process can be analyzed in terms of the simultaneous scattering of light by the two sound waves in the interaction region. Analytic expressions for the equivalent transfer functions are obtained and the scattered light profiles are plotted.