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1993

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Full-Text Articles in Physics

Comparison Of Suppression Across Frequencies, Linda M. Thibodeau, Marc A. Fagelson Nov 1993

Comparison Of Suppression Across Frequencies, Linda M. Thibodeau, Marc A. Fagelson

Marc A. Fagelson

Although much research has focused on the temporal, spectral, and intensity relationships between a masker and a suppressor, there has been little attention directed towards relative amounts of suppression in different frequency regions. The purpose of this experiment was to compare the magnitude of suppression at 500 and 2000 Hz in two forward‐masking experiments with seven normal‐hearing persons. In the first experiment, the threshold for a 10‐ms probe was determined as the bandwidth of a 400‐ms masker increased from 0.05 to 1.6 times the probe frequency. Suppression was determined by observing a decrease in ...


Selected Topics On Dynamical Symmetry Breaking, Tonnis Ter Veldhuis Jul 1993

Selected Topics On Dynamical Symmetry Breaking, Tonnis Ter Veldhuis

Tonnis ter Veldhuis

No abstract provided.


Transverse Form Factors Of 117sn, H Baghaei, J Dubach, M B. Frodyma, R S. Hicks, R A. Miskimen, Gerald Alvin Peterson Jul 1993

Transverse Form Factors Of 117sn, H Baghaei, J Dubach, M B. Frodyma, R S. Hicks, R A. Miskimen, Gerald Alvin Peterson

Gerald Alvin Peterson

Transverse elastic and inelastic form factors for low-lying levels in 117Sn have been measured by 180° electron scattering in the momentum transfer range qeff=1.1–2.4 fm-1. The simple independent-particle model fails to account for these data, predicting form factors that are much too large. In better quantitative agreement with the data are the results of more detailed calculations that allow for configuration mixing of valence nucleons, as well as first-order core polarization. As in the similar case of 205Tl, these calculations successfully predict the presence of a deep diffraction minimum observed in the intermediate q region of ...


Apparent And True Feature Heights In Force Microscopy, Nancy Burnham Jul 1993

Apparent And True Feature Heights In Force Microscopy, Nancy Burnham

Nancy A. Burnham

In a force microscope, the stiffness of the cantilever beam convolutes with the tip‐sample interaction stiffness to influence the data in a systematic way. The analysis presented here relates the measured feature height to the true feature height in the variable force, constant force, and constant force gradient modes of operation. In this way, one can understand previously published data: the enhanced measured atomic corrugation observed in high resolution force microscopy images, its increase with load, and the improved resolution of lateral force images. The correct interaction stiffness can be obtained for use in surface force and mechanical properties ...


Ground-State Magnetization Density Of 89y, J E. Wise, J R. Calarco, J P. Connelly, S A. Fayans, F W. Hersman, J H. Heisenberg, R S. Hicks, W Kim, T E. Milliman, R A. Miskimen, Gerald Alvin Peterson May 1993

Ground-State Magnetization Density Of 89y, J E. Wise, J R. Calarco, J P. Connelly, S A. Fayans, F W. Hersman, J H. Heisenberg, R S. Hicks, W Kim, T E. Milliman, R A. Miskimen, Gerald Alvin Peterson

Gerald Alvin Peterson

Elastic electron scattering cross sections have been measured for 89Y at 180° for 0.72


Viscoelastic Properties Of A Bent And Straight Dimeric Liquid Crystal, Gregory A. Dilisi, Charles Rosenblatt, Anselm C. Griffin, Eugene M. Terentjev Apr 1993

Viscoelastic Properties Of A Bent And Straight Dimeric Liquid Crystal, Gregory A. Dilisi, Charles Rosenblatt, Anselm C. Griffin, Eugene M. Terentjev

Gregory A. DiLisi

Absolute values for the elastic constants and viscosities are reported in the nematic phase for two dimers based upon the monomer 4.4'-dipentyloxyphenylbenzoate. One dimer has an even number of methylene units in the spacer and, in consequence, is approximately straight in the all-trans conformation. The other dimer has one less methylene unit, and is therefore bent. We find that the ratio K33/K11 for the odd dimer is reduced relative to that for the even member of the series. Moreover, we find that the absolute elastic constants for the odd dimer are of order one-half that of the ...


Measurements Of Transverse Electron Scattering From The Deuteron In The Threshold Region At High Momentum Transfers, M Frodyma, R G. Arnold, D Benton, P E. Bosted, L Clogher, G Dechambrier, A T. Katramatou, J Lambert, A Lung, G G. Petratos, A Rahbar, S E. Rock, Z M. Szalata, B Debebe, R S. Hicks, A Hotta, Gerald Alvin Peterson Mar 1993

Measurements Of Transverse Electron Scattering From The Deuteron In The Threshold Region At High Momentum Transfers, M Frodyma, R G. Arnold, D Benton, P E. Bosted, L Clogher, G Dechambrier, A T. Katramatou, J Lambert, A Lung, G G. Petratos, A Rahbar, S E. Rock, Z M. Szalata, B Debebe, R S. Hicks, A Hotta, Gerald Alvin Peterson

Gerald Alvin Peterson

Deuteron electrodisintegration cross sections near 180' have been measured near breakup threshold for the four-momentum transfer squared Q' range 1.21—2.76 (GeV/c) . Evidence for a change of slope in the cross section near Q =1 (GeV/c ) has been obtained. The data are compared to nonrelativistic calculations, which predict a strong influence of meson-exchange currents. The data are also compared to a hybrid quark-hadron model ~ None of these calculations agrees with the data over the entire measured range of Q'. The ratio of inelastic structure functions W, (Q', E„~)/Wz(Q', E„~)is extracted from the present ...


Measurements Of The Electric And Magnetic Form Factors Of The Neutron From Q2=1.75 To 4.00 (Gev/C)2, A Lung, L M. Stuart, P E. Bosted, L Andivahis, J Alster, R G. Arnold, C C. Chang, F S. Dietrich, W R. Dodge, R Gearhart, J Gomez, K A. Griffioen, R S. Hicks, R A. Miskimen, Gerald Alvin Peterson Feb 1993

Measurements Of The Electric And Magnetic Form Factors Of The Neutron From Q2=1.75 To 4.00 (Gev/C)2, A Lung, L M. Stuart, P E. Bosted, L Andivahis, J Alster, R G. Arnold, C C. Chang, F S. Dietrich, W R. Dodge, R Gearhart, J Gomez, K A. Griffioen, R S. Hicks, R A. Miskimen, Gerald Alvin Peterson

Gerald Alvin Peterson

Quasielastic e-d cross sections have been measured at forward and backward angles. Rosenbluth separations were done to obtain RL and RT at Q2=1.75, 2.50, 3.25, and 4.00 (GeV/c)2. The neutron form factors GEn and GMn have been extracted using a nonrelativistic model. The sensitivity to deuteron wave function, relativistic corrections, and models of the inelastic background are reported. The results for GMn are consistent with the dipole form, while GEn is consistent with zero. Comparisons are made to theoretical models based on vector meson dominance, perturbative QCD, and QCD sum rules, as well ...


Organo-Soluble Segmented Rigid-Rod Polyimide Films Part 3: Effects Of Copolymer Composition On Thermal Expansivity And On Relaxation Processes, Stephen Z. D. Cheng Jan 1993

Organo-Soluble Segmented Rigid-Rod Polyimide Films Part 3: Effects Of Copolymer Composition On Thermal Expansivity And On Relaxation Processes, Stephen Z. D. Cheng

Stephen Z. D. Cheng

A series of copolyimides based on 3,3',4,4'-biphenyltetracarboxylic dianhydride (BPDA), pyromellitic dianhydride (PMDA) (1,2,4,5,-benzenetetracarboxylic dianhydride) and 2,2'-bis(trifluoromethyl) benzidene (PFMB) have been synthesized with varying BPDA-PFMB and PMDA-PFMB compositions. A systematic change in the linear coefficient of thermal expansion (CTE) and the glass-transition temperature (T(g)) is observed by changing the ratios of the BPDA-PFMB and PMDA-PFMB compositions. Both the CTEs and T(g)s have been found to follow the molar-additivity rules. Dynamic mechanical experiments manifest two relaxation processes above room temperature. A subglass beta relaxation, which is independent of ...


Burnham, Colton, And Pollock Reply, Nancy Burnham, Rj Colton, Hm Pollock Jan 1993

Burnham, Colton, And Pollock Reply, Nancy Burnham, Rj Colton, Hm Pollock

Nancy A. Burnham

It is not necessary to obtain permission to reuse this article or its components as it is available under the terms of the Creative Commons Attribution 3.0 License. This license permits unrestricted use, distribution, and reproduction in any medium, provided attribution to the author (s) and the published article's title, journal citation, and DOI are maintained. Please note that some figures may have been included with permission from other third parties. It is your responsibility to obtain the proper permission from the rights holder


Anomalies For Pedestrians, Br Holstein Dec 1992

Anomalies For Pedestrians, Br Holstein

Barry R Holstein

The subject of anomalies, i.e., quantum mechanical symmetry breaking, is addressed using only basic quantum mechanics. Examples from different areas of physics are examined


Study Of The Violation Of Parity In Nuclear Beta-Decay Via A Relative Beta-Polarization Measurement With Polarized In-107 Nuclei, N Severijns, R Prieels, M Allet, J Camps, P Demoor, J Deutsch, F Gimenonogues, Br Holstein, Bh King, O Naviliatcuncici, I Pepe, Pa Quin, P Schuurmans, R Siebelink, W Vanderpoorten, J Vanhaverbeke, L Vanneste, J Wouters Dec 1992

Study Of The Violation Of Parity In Nuclear Beta-Decay Via A Relative Beta-Polarization Measurement With Polarized In-107 Nuclei, N Severijns, R Prieels, M Allet, J Camps, P Demoor, J Deutsch, F Gimenonogues, Br Holstein, Bh King, O Naviliatcuncici, I Pepe, Pa Quin, P Schuurmans, R Siebelink, W Vanderpoorten, J Vanhaverbeke, L Vanneste, J Wouters

Barry R Holstein

No abstract provided.


Solvable Quantum Mechanical Examples Of Broken Supersymmetry, Asim Gangopadhyaya Dec 1992

Solvable Quantum Mechanical Examples Of Broken Supersymmetry, Asim Gangopadhyaya

Asim Gangopadhyaya

We construct several analytically solvable examples of broken supersymmetry in non-relativistic quantum mechanics. Our examples are motivated from known shape-invariant potentials obeying unbroken supersymmetry and are obtained from them via suitable mapping procedures.


Quantum Correlations And 3 Body Decays At A Phi-Factory, Jf Donoghue, Br Holstein, Af Perez Dec 1992

Quantum Correlations And 3 Body Decays At A Phi-Factory, Jf Donoghue, Br Holstein, Af Perez

Barry R Holstein

No abstract provided.


Phenomenographic Research And The Measurement Of Understanding: An Investigation Of Students' Conceptions Of Speed, Distance And Time, P Ramsden, Geoff Masters, Andrew Stephanou, E Walsh, E Martin Dec 1992

Phenomenographic Research And The Measurement Of Understanding: An Investigation Of Students' Conceptions Of Speed, Distance And Time, P Ramsden, Geoff Masters, Andrew Stephanou, E Walsh, E Martin

Prof Geoff Masters AO

No abstract provided.


Physics Students' Understanding Of Relative Speed: A Phenomenographic Study, Eleanor Walsh, Gloria Dall'alba, John Bowden, Elaine Martin, Ference Marton, Geoff Masters, Paul Ramsden, Andrew Stephanou Dec 1992

Physics Students' Understanding Of Relative Speed: A Phenomenographic Study, Eleanor Walsh, Gloria Dall'alba, John Bowden, Elaine Martin, Ference Marton, Geoff Masters, Paul Ramsden, Andrew Stephanou

Prof Geoff Masters AO

It is important that students of physics develop both quantitative and qualitative understanding of physical concepts and principles. Although accuracy and reliability in solving quantitative problems is necessary, a qualitative understanding is required in applying concepts and principles to new problems and in real-life situations. If students are not able to understand what underlies quantitative problem-solving procedures nor interpret the solution in physical terms, it is questionable whether they have developed an adequate understanding of physics. The research reported here is part of a larger phenomenographic study that is concerned with the assessment of physics students' understanding of some basic ...


Equivalence Theorem And Global Anomalies, John Donoghue, Jusak Tandean Dec 1992

Equivalence Theorem And Global Anomalies, John Donoghue, Jusak Tandean

John Donoghue

In the presence of some forms of global anomalies, the equivalence theorem, which relates the interactions of longitudinal gauge bosons to those of the Goldstone bosons, is not always valid. This can occur when the Goldstone sector contains an anomaly which is canceled in the gauge currents by the effects of a different sector of the theory. The example of the standard model without Higgs particles is used to illustrate this phenomena.


Quantum Correlations In Three Body Ö Decay, John Donoghue, Barry Holstein, Antonio Perez Dec 1992

Quantum Correlations In Three Body Ö Decay, John Donoghue, Barry Holstein, Antonio Perez

John Donoghue

The decays of neutral kaons produced in ~b decay, (~-~KLKs, exhibit interesting quantum mechanical interference. The effects of this phenomenon on searches for CP violation have been previously been worked out for two body decays where the decay amplitude is a simple constant. For three body modes, where the matrix element varies across the kinematically allowed region, the quantum correlations will enhance or cancel certain terms in the decay distribution. We work out the results for two interesting modes q)~(nn)(nnT) and ~b~(3n)(3n). In the former case, the quantum correlation allows the isolation of the direct emission ...


Photon-Photon Scattering, Pion Polarizability And Chiral Symmetry, John Donoghue, Barry Holstein Dec 1992

Photon-Photon Scattering, Pion Polarizability And Chiral Symmetry, John Donoghue, Barry Holstein

John Donoghue

Recent attempts to detect the pion polarizability via analysis of γγ → ππ measurements are examined. The connection between calculations based on dispersion relations and on chiral perturbation theory is established by matching the low energy chiral amplitude with that given by a full dispersive treatment. Using the values for the polarizability required by chiral symmetry, predicted and experimental cross sections are shown to be in agreement. 


Electromagnetic Self Energies Of Pseudoscalar Mesons And Dashen's Theorem, John Donoghue, Barry Holstein, Daniel Wyler Dec 1992

Electromagnetic Self Energies Of Pseudoscalar Mesons And Dashen's Theorem, John Donoghue, Barry Holstein, Daniel Wyler

John Donoghue

The calculation of the electromagnetic mass shifts of pi, K mesons is studied using a model incorporating chiral symmetry and vector dominance. Significant SU(3) breaking to Dashen s theorem is found, allowing a resolution of the long-standing discrepancy between the quark-mass ratio (md —m„)/I, found from g->3pi decay and that from the K+-K0 mass difference. 


Sliding Mode Control Of The Systems With Uncertain Direction Of Control Vector, Sergey V. Drakunov Dec 1992

Sliding Mode Control Of The Systems With Uncertain Direction Of Control Vector, Sergey V. Drakunov

Sergey V. Drakunov

No abstract provided.


Doping And Pressure Studies On Ybbipt, A. Lacerda, R. Movshovich, M. F. Hundley, Paul C. Canfield, D. Arms, G. Sparn, J. D. Thompson, Z. Fisk, N. E. Philips, H.-R. Ott Dec 1992

Doping And Pressure Studies On Ybbipt, A. Lacerda, R. Movshovich, M. F. Hundley, Paul C. Canfield, D. Arms, G. Sparn, J. D. Thompson, Z. Fisk, N. E. Philips, H.-R. Ott

Paul C. Canfield

The compound YbBiPt exhibits an extremely large low‐temperature C/T (γ∼8 J K−2 mol−1/Yb) which, if due solely to a renormalized effective mass, would make this material the heaviest correlated electron system known to date. In the Kondo model, the very large γ corresponds to a small characteristic energy scale that is expected to be pressure dependent. We have studied the effect of chemical pressure on YbBiPt single crystals by heat‐capacity measurements on Y and Lu‐doped samples. We have also made preliminary low‐temperature measurements under hydrostatic pressure of the heat capacity (300 ...