TY - JOUR TI - Surface morphology and kinetic roughening of Ag on Ag(111) studied with scanning tunneling microscopy AU - Heyvaert, I. AU - Krim, J. AU - Van Haesendonck, C. AU - Bruynseraede, Y. T2 - Physical Review E - Statistical Physics, Plasmas, Fluids, and Related Interdisciplinary Topics AB - The topography of Ag grown on Ag(111) measured with scanning tunneling microscopy reveals three-dimensional, layered islands for film thicknesses below 500 \AA{}. For thicker Ag films, the layered structures can no longer be observed. The induced surface roughness increases with increasing film thickness and corresponds to the formation of self-similar surfaces with roughness exponents H close to 1 for thicknesses up to 5000 \AA{}. Our results are compared to the relevant theoretical models. \textcopyright{} 1996 The American Physical Society. DA - 1996/// PY - 1996/// DO - 10.1103/PhysRevE.54.349 VL - 54 IS - 1 SP - 349-353 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-0030193584&partnerID=MN8TOARS ER - TY - JOUR TI - Sliding friction of solid xenon monolayers and bilayers on Ag(111) AU - Daly, C. AU - Krim, J. T2 - Physical Review Letters AB - We have measured the force required to slide one- and two-atom-thick solid films of xenon along a Ag(111) surface, and observe that the friction associated with the bilayer is approximately 25% greater than that associated with the monolayer. Our result sheds new light on the nature of atomic-scale frictional energy dissipation mechanisms, and demonstrates how localized to an interface such mechanisms can be. DA - 1996/// PY - 1996/// DO - 10.1103/PhysRevLett.76.803 VL - 76 IS - 5 SP - 803-806 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-0000162657&partnerID=MN8TOARS ER - TY - JOUR TI - Friction and damping of Xe/Ag(111) AU - Daly, C. AU - Krim, J. T2 - Surface Science AB - We have measured the force required to slide molecularly thin xenon films along Ag(111), and observe that the friction associated with the sliding is highly sensitive to the xenon film's lattice spacing. Our result sheds light on the relative contributions of lattice vibrations (phonons) and electronic mechanisms to the total frictional energy dissipation. DA - 1996/// PY - 1996/// DO - 10.1016/S0039-6028(96)01027-8 VL - 368 IS - 1-3 SP - 49-54 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-0030412959&partnerID=MN8TOARS ER - TY - JOUR TI - Fractal scaling behavior of water flow patterns on inhomogeneous surfaces AU - Tomassone, M.S. AU - Krim, J. T2 - Physical Review E - Statistical Physics, Plasmas, Fluids, and Related Interdisciplinary Topics AB - We have analyzed the patterns formed by water flowing over an inhomogeneous incline and have found fractal scaling behavior in the downhill direction, with ${d}_{f}=1.35\ensuremath{-}1.45$. The observed behavior is consistent with recent theoretical predictions involving nonlinear fluid flow close to threshold conditions. DA - 1996/// PY - 1996/// DO - 10.1103/PhysRevE.54.6511 VL - 54 IS - 6 SP - 6511-6515 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-2342449048&partnerID=MN8TOARS ER - TY - JOUR TI - Adsorption isotherms and thermal fluctuations AU - Mecke, K. AU - Krim, J. T2 - Physical Review B - Condensed Matter and Materials Physics AB - The influence of thermal fluctuations on adsorption isotherms is calculated within the context of a self-consistent mean-field theory, and it is found that such fluctuations cannot be neglected in the analysis of adsorption data. This result arises from our observation that substrate-induced hindrance of thermal fluctuations can significantly alter the form of an adsorption isotherm, particularly in the thin-film regime (\ensuremath{\approx}0-5 nm) which is most commonly probed by adsorption experiments. Previous experiments involving room-temperature adsorption on flat surfaces have been reanalyzed, and the reported discrepancies with the Lifshitz theory of van der Waals forces are found to be much reduced when thermal fluctuations of the thickness of the adsorbed layer are taken into account. Recently published data for nitrogen adsorption on rough substrates have also been reanalyzed, and the thermal fluctuations are found to be more important for thin adsorbed layers than undulations of the film induced by the roughness of the substrate. The analysis reveals that, as long suspected, the scaling regime of asymptotic divergence has not yet been reached for film thicknesses remaining below 5 nm. DA - 1996/// PY - 1996/// DO - 10.1103/PhysRevB.53.2073 VL - 53 IS - 4 SP - 2073-2082 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-0000885117&partnerID=MN8TOARS ER - TY - JOUR TI - Adequacy of the lifshitz theory for certain thin adsorbed films AU - Panella, V. AU - Chiarello, R. AU - Krim, J. T2 - Physical Review Letters AB - We have employed a quartz crystal microbalance technique to study the thickness versus pressure dependence of a variety of thin (0--5 nm) liquid films (water, cyclohexane, nitrogen, krypton, and xenon) adsorbed on metal surfaces. We observe the Lifshitz theory of van der Waals forces to provide an excellent description of nitrogen adsorption, and an inadequate description of water adsorption, with the remaining gases spanning the two extremes. DA - 1996/// PY - 1996/// DO - 10.1103/PhysRevLett.76.3606 VL - 76 IS - 19 SP - 3606-3609 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-0000571525&partnerID=MN8TOARS ER - TY - JOUR TI - Friction at the atomic scale AU - Krim, Jacqueline T2 - Scientific American DA - 1996/// PY - 1996/// DO - 10.1038/scientificamerican1096-74 VL - 275 IS - 4 SP - 74-80 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-0030270665&partnerID=MN8TOARS ER - TY - JOUR TI - Atomic-scale origins of frictiont AU - Krim, J. T2 - Langmuir DA - 1996/// PY - 1996/// VL - 12 IS - 19 SP - 4564-4566 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-0001626306&partnerID=MN8TOARS ER - TY - CONF TI - Static Orientation of Nuclear Targets AU - Haase, D.G. AU - Gould, C.R. AU - Keith, C.D. AU - Seely, M.L. AU - Huffman, P.R. AU - Roberson, N.R. AU - Tornow, W. AU - Wilburn, W.S. T2 - Eighth International Conference on Polarized Target Materials and Techniques (TRIUMF) C2 - 1996/// C3 - Proceedings of the Eighth International Conference on Polarized Target Materials and Techniques (TRIUMF CY - Vancouver DA - 1996/// PY - 1996/// ER - TY - CONF TI - Calibrating Target Polarization in a Polarized Neutron-Polarized Proton Scattering Experiment AU - Seely, M.L. AU - Gould, C.R. AU - Haase, D.G. AU - Raichle, B.R. AU - Walston, J.R. AU - Roberson, N.R. AU - Tornow, W. AU - Wilburn, W.S. AU - Penttila, S.I. AU - Hoffman, G.W. T2 - Eighth International Conference on Polarized Target Materials and Techniques (TRIUMF) C2 - 1996/// C3 - Proceedings of the Eighth International Conference on Polarized Target Materials and Techniques (TRIUMF) CY - Vancouver DA - 1996/// PY - 1996/// ER - TY - CONF TI - Questions Regarding Microwave Induced Optical Nuclear Polarization AU - Seely, M.L. AU - Gould, C.R. AU - Haase, D.G. AU - Raichle, B.R. AU - Walston, J.R. AU - Roberson, N.R. AU - Tornow, W. AU - Wilburn, W.S. T2 - Eighth International Conference on Polarized Target Materials and Techniques (TRIUMF) C2 - 1996/// C3 - Proceedings of the Eighth International Conference on Polarized Target Materials and Techniques (TRIUMF) CY - Vancouver DA - 1996/// PY - 1996/// ER - TY - JOUR TI - A high-rate detection system to study parity violation with polarized epithermal neutrons at LANSCE AU - Knudson, J. N. AU - Bowman, J. D. AU - Crawford, B. E. AU - Delheij, P. P. J. AU - Frankle, C. M. AU - Gould, C. R. AU - Haase, D. G. AU - Iinuma, M. AU - Lowie, L. Y. AU - Masaike, A. AU - Masuda, Y. AU - Matsuda, Y. AU - Mitchell, G. E. AU - Penttila, S. I. AU - Postma, H. AU - Roberson, N. R. AU - Seestrom, S. J. AU - Sharapov, E. I. AU - Shimizu, H. M. AU - Stephenson, S. L. AU - Yen, Y. F. AU - Yuan, V. W. AU - Yoo, S. H. T2 - Journal of Neutron Research AB - We describe an apparatus for studies of parity violation in neuwn-nucleus scattering. This experiment requires longitudinally polarized neutrons from the Los Alamos Neutron Scattering Center over the energy range from 1 to l000 eV, the ability to rev DA - 1996/12/1/ PY - 1996/12/1/ DO - 10.1080/10238169608200086 VL - 4 IS - 1 SP - 209-213 J2 - GNER LA - en OP - SN - 1023-8166 UR - http://dx.doi.org/10.1080/10238169608200086 DB - Crossref ER - TY - JOUR TI - A solenoidal spectrometer for positron-electron pairs produced in heavy-ion collisions AU - Ahmad, I. AU - Austin, Sam.M. AU - Back, B.B. AU - Betts, R.R. AU - Calaprice, F.P. AU - Chan, K.C. AU - Chishti, A. AU - Chowdhury, P. AU - Conner, C. AU - Dunford, R.W. AU - Fox, J.D. AU - Freedman, S.J. AU - Freer, M. AU - Gazes, S.B. AU - Greenberg, J.S. AU - Greene, J.P. AU - Hallin, A.L. AU - Happ, Th. AU - Henderson, D. AU - Kaloskamis, N.I. AU - Kashy, E. AU - Kutschera, W. AU - Last, J. AU - Lister, C.J. AU - Liu, M. AU - Maier, M.R. AU - Mercer, D.M. AU - Mikolas, D. AU - Perera, P.A.A. AU - Rhein, M.D. AU - Roa, D.E. AU - Schiffer, J.P. AU - Trainor, T.A. AU - Wilt, P. AU - Winfield, J.S. AU - Wolanski, M. AU - Wolfs, F.L.H. AU - Wuosmaa, A.H. AU - Xu, G. AU - Young, A.R. AU - Yurkon, J.E. T2 - Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment AB - A new solenoidal spectrometer, designed to study the production mechanism of electrons and positrons in heavy-ion collisions, has been constructed at Argonne National Laboratory. The spectrometer uses a 300 G magnetic field to transport the leptons to two highly segmented silicon arrays that are centered on the solenoid axis, 1.2 m from the target. Positrons are identified by detecting their annihilation radiation with two arrays of position sensitive NaI(Tl) crystals that surround the silicon arrays. A novel design feature of the spectrometer is the ability to measure the angles of emission of the leptons relative to the solenoid axis. The measured response of the apparatus to electrons and positrons is in very good agreement with the calculated response obtained from Monte Carlo simulations. DA - 1996/2// PY - 1996/2// DO - 10.1016/0168-9002(95)00829-2 VL - 370 IS - 2-3 SP - 539-557 J2 - Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment LA - en OP - SN - 0168-9002 UR - http://dx.doi.org/10.1016/0168-9002(95)00829-2 DB - Crossref ER - TY - JOUR TI - Absolute measurement of dielectronic recombination forC3+in a known external field AU - Savin, D. W. AU - Gardner, L. D. AU - Reisenfeld, D. B. AU - Young, A. R. AU - Kohl, J. L. T2 - Physical Review A AB - An absolute measurement of the rate coefficient for dielectronic recombination (DR) of ${\mathrm{C}}^{3+}$, via the 2s-2p core excitation, in an external electric field of 11.4\ifmmode\pm\else\textpm\fi{}0.9(1\ensuremath{\sigma}) V ${\mathrm{cm}}^{\mathrm{\ensuremath{-}}1}$ is presented. An inclined-beam arrangement is used and the stabilizing photons at \ensuremath{\sim}155 nm are detected in delayed coincidence with the recombined ions. The full width at half maximum of the electron energy spread in the ion rest frame is 1.74\ifmmode\pm\else\textpm\fi{}0.22(1\ensuremath{\sigma}) eV. The measured DR rate, at a mean electron energy of 8.26\ifmmode\pm\else\textpm\fi{}0.07(1\ensuremath{\sigma}) eV, is (2.76\ifmmode\pm\else\textpm\fi{}0.75)\ifmmode\times\else\texttimes\fi{}${10}^{\mathrm{\ensuremath{-}}10}$ ${\mathrm{cm}}^{3}$ ${\mathrm{s}}^{\mathrm{\ensuremath{-}}1}$. The uncertainty quoted for the DR rate is the total uncertainty, systematic and statistical, at the 1\ensuremath{\sigma} level. In comparing the present results to theory, a semiempirical formula is used to determine which recombined ion states are ionized by the 4.65 kV ${\mathrm{cm}}^{\mathrm{\ensuremath{-}}1}$ fields in the final-charge-state analyzer and not detected. For the present results, any DR of the incident electrons into n levels greater than 44 is assumed to be field ionized in the final-charge-state analyzer. A more precise treatment of field ionization, which includes the lifetime of the ${\mathrm{C}}^{2+}$ ions before they are ionized and the time evolution and rotation of the fields experienced by the recombined ions, is needed before a definitive comparison between experiment and theory can be made. Our DR measurement, within the limits of that approach, agrees reasonably well with an intermediate coupling calculation that uses an isolated resonance, single-configuration approximation, but does not agree with pure LS-coupling calculations. \textcopyright{} 1996 The American Physical Society. DA - 1996/1/1/ PY - 1996/1/1/ DO - 10.1103/physreva.53.280 VL - 53 IS - 1 SP - 280-289 J2 - Phys. Rev. A LA - en OP - SN - 1050-2947 1094-1622 UR - http://dx.doi.org/10.1103/physreva.53.280 DB - Crossref ER - TY - JOUR TI - Laser-polarized muonic3He and a measurement of the induced pseudoscalar coupling AU - Bogorad, P. AU - Behr, J. AU - Brash, E. J AU - Cates, G. D. AU - Cummings, W. J. AU - Gorelov, A. AU - Hasinoff, M. D. AU - Hausser, O. AU - Hicks, K. AU - Holmes, R. AU - Huang, J. C. AU - Kumar, K. S. AU - Larson, B. AU - Lorentzon, W. AU - McCracken, J. AU - Middleton, H. AU - Michaux, P. AU - Saettler, E. AU - Siegel, D. AU - Souder, P. A. AU - Swenson, D. R. AU - Tupa, D. AU - Wang, X. AU - Young, A. T2 - Hyperfine Interactions DA - 1996/12// PY - 1996/12// DO - 10.1007/bf02227653 VL - 101-102 IS - 1 SP - 433-437 J2 - Hyperfine Interact LA - en OP - SN - 0304-3834 1572-9540 UR - http://dx.doi.org/10.1007/bf02227653 DB - Crossref ER - TY - RPRT TI - Determining and Interpreting Resistive Electric Circuits Test AU - Engelhardt, P. AU - Beichner, R. A3 - North Carolina State University DA - 1996/// PY - 1996/// M3 - Version 1.2 PB - North Carolina State University ER - TY - BOOK TI - The Test of Understanding Graphs–Kinematics AU - Beichner, R. A3 - Redish, E.F. DA - 1996/// PY - 1996/// M3 - CD-ROM Version 2.6 PB - North Carolina State University ER - TY - JOUR TI - gboson and systematics of theM1 scissors mode AU - Davis, E. D. AU - Diallo, A. F. AU - Barrett, B. R. T2 - Physical Review C AB - We discuss systematics of the M1 scissors mode within the interacting boson model when the g-boson degree of freedom is included explicitly and microscopically motivated choices of model parameters are adopted. We try to relate the M1 centroid energy to the energetics of deformation. We conclude that, with the introduction of a hexadecapole-hexadecapole interaction and a g-boson admixture in the ground state of only a few percent, we can obtain reasonable estimates of the M1 centroid energy, without invoking a Majorana interaction. If one takes seriously variations in microscopic estimates of boson g factors, then the summed M1 strength near midshell can be interpreted in terms of boson occupation numbers which saturate. \textcopyright{} 1996 The American Physical Society. DA - 1996/6/1/ PY - 1996/6/1/ DO - 10.1103/physrevc.53.2849 VL - 53 IS - 6 SP - 2849-2854 J2 - Phys. Rev. C LA - en OP - SN - 0556-2813 1089-490X UR - http://dx.doi.org/10.1103/physrevc.53.2849 DB - Crossref ER - TY - CONF TI - Theory of Group-IV Impurities in Wide Gap Nitrides AU - Boguslawski, P. AU - Bernholc, J. T2 - 23rd International Conference on the Physics of Semiconductors A2 - Scheffler, Matthias A2 - Zimmermann, Roland C2 - 1996/// C3 - 23rd International Conference on the Physics of Semiconductors : Berlin, Germany, July 21-26, 1996 CY - Berlin, Germany DA - 1996/// PY - 1996/7/21/ SP - 2889 PB - World Scientific ER - TY - CONF TI - Theory of Surfaces and Interfaces in Wide-Gap Nitrides AU - Rapcewicz, K.L. AU - Buongiorno Nardelli, M. AU - Chen, B. AU - Zhang, Z. AU - Bernholc, J. T2 - First Symposium on III-V Nitride Materials and Processes A2 - Moustakas, T.D. A2 - Dismukes, J.P. A2 - Pearton, S.J. C2 - 1996/// C3 - Proceedings of the First Symposium on III-V Nitride Materials and Processes CY - Los Angeles, California DA - 1996/// PY - 1996/5/6/ SP - 76-86 PB - Electrochemical Society SN - 1566771633 ER - TY - CONF TI - Ab Initio Simulations of Materials AU - Bernholc, J. AU - Boguslawski, P. AU - Brabec, C. AU - Biggs, E.L. AU - Maiti, A. AU - Roland, C. AU - Sullivan, D.J. AU - Wensell, M. AU - Yakobson, B. AU - Zhang, Q.-M. AU - Zhang, Z. T2 - Science and technology of atomically engineered materials conference A2 - Jena, P. A2 - Khanna, S.N. A2 - Rao, B.K. C2 - 1996/// C3 - Proceedings of the Science And Technology Of Atomically Engineered Materials CY - Richmond, Virginia DA - 1996/// PY - 1995/10/30/ SP - 193-200 PB - World Scientific Publishing Co. Pte. Ltd. SN - 0789814531320 ER - TY - JOUR TI - A Circumstellar Shell Model for the Cassiopeia A Supernova Remnant AU - Borkowski, Kazimierz AU - Szymkowiak, Andrew E. AU - Blondin, John M. AU - Sarazin, Craig L. T2 - The Astrophysical Journal AB - view Abstract Citations (63) References (29) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS A Circumstellar Shell Model for the Cassiopeia A Supernova Remnant Borkowski, Kazimierz ; Szymkowiak, Andrew E. ; Blondin, John M. ; Sarazin, Craig L. Abstract We model the Cassiopeia A supernova remnant in the framework of the circumstellar medium (C SM) interaction picture. In this model, the slow red supergiant wind of the supernova (SN) progenitor was swept into a dense shell by a fast stellar wind in the subsequent blue supergiant stage of the progenitor star. The supernova blast wave propagated quickly (≤ 100 yr) through the tenuous wind-blown bubble located within this shell and then slowed down in the dense (nH ∼15 cm-3) CSM shell. The shell was impulsively accelerated during this interaction stage; during the subsequent interaction with SN ejecta, the shell has been further accelerated to ∼2000 km s-1, the currently observed expansion rate. The comparison of our X-ray emission calculations with the ASCA spectrum suggests that about 8 Msun of X- material is present in Cas A. Most of this mass is located in the CSM shell and in the outlying red supergiant wind. The X-ray continuum and the Fe Kα line are dominated by the shell emission, but prominent Kα complexes of Mg, Si, and S must be produced by SN ejecta with strongly enhanced abundances of these elements. Our hydrodynamical models indicate that about 2 Msun of ejecta have been shocked. An explosion of a stellar He core is consistent with these findings. Publication: The Astrophysical Journal Pub Date: August 1996 DOI: 10.1086/177560 Bibcode: 1996ApJ...466..866B Keywords: ISM: SUPERNOVA REMNANTS; HYDRODYNAMICS; ISM: INDIVIDUAL NAME: CASSIOPEIA A; STARS: CIRCUMSTELLAR MATTER full text sources ADS | data products SIMBAD (1) HEASARC (1) DA - 1996/8// PY - 1996/8// DO - 10.1086/177560 VL - 466 SP - 866 KW - circumstellar matter KW - hydrodynamics KW - ISM, individual (Cassiopeia A) KW - supernova remnants ER - TY - JOUR TI - The Shaping of Planetary Nebulae: Asymmetry in the External Wind AU - Dwarkadas, Vikram V. AU - Chevalier, Roger A. AU - Blondin, John M. T2 - The Astrophysical Journal AB - view Abstract Citations (51) References (53) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS The Shaping of Planetary Nebulae: Asymmetry in the External Wind Dwarkadas, Vikram V. ; Chevalier, Roger A. ; Blondin, John M. Abstract We have modeled planetary nebulae (PNs) in the context of the interacting stellar winds model. If the two interacting winds have constant properties, the velocity of the PN shell tends toward a constant with time and the shape becomes self-similar. Additionally, if the velocity of the fast wind is much higher than the expansion velocity of the shell, the interior of the hot shocked bubble becomes isobaric. Using semi-analytical methods, complemented by hydrodynamic simulations, we have calculated the shapes of PNs in the self-similar stage. An asymmetric density profile is assumed for the slow outer wind. The asymmetry is modeled using different functions, which depend on the degree of asymmetry and the steepness of the density profile in the angular direction. We include the effects of the ambient wind velocity, which has not received much attention since the work of Kahn & West (1985). The fact that typical PN velocities (10-40 km s-1) are only marginally greater than typical red giant wind velocities (5-20 km s-1) indicates that this is an important parameter. The morphological appearance is a consequence of the density contrast, steepness of the density profile and velocity of the ambient medium; classification of PNs purely on the basis of the first two factors may be misleading. Moderate values of the density contrast result in a cusp at the equator. A higher density contrast coupled with a low velocity for the external medium gives rise to extremely bipolar nebulae. For large density contrasts and a significant value of the slow wind velocity, the surface density maximum of the shell shifts away from the equator, giving rise to peanut-shaped structures with pronounced equatorial bulges. If the external wind velocity is small compared to the expansion velocity of the nebula, the PNs tend to be more bipolar, even with a moderate density contrast. If the PN velocity is close to that of the external wind, the shape is relatively spherical. However, a velocity asymmetry in the external wind can lead to a bipolar shape if the equatorial velocity is sufficiently low. Our numerical simulations show that asymmetric PN shells are corrugated because of Kelvin-Helmholtz instabilities. They also indicate that several doubling times are needed to approach the self-similar state. A ratio of interior sound speed to shell velocity ≳10 is found to yield nebulae whose shapes match those given by the isobaric approximation. Publication: The Astrophysical Journal Pub Date: February 1996 DOI: 10.1086/176772 Bibcode: 1996ApJ...457..773D Keywords: HYDRODYNAMICS; ISM: BUBBLES; ISM: STRUCTURE; ISM: PLANETARY NEBULAE: GENERAL; STARS: MASS LOSS full text sources ADS | data products SIMBAD (12) DA - 1996/2// PY - 1996/2// DO - 10.1086/176772 VL - 457 SP - 773 KW - hydrodynamics KW - ISM, bubbles KW - ISM, structure KW - planetary nebulae, general KW - stars, mass loss ER - TY - JOUR TI - Axisymmetric Circumstellar Interaction in Supernovae AU - Blondin, John M. AU - Lundqvist, Peter AU - Chevalier, Roger A. T2 - The Astrophysical Journal AB - Multiwavelength observations of Type II supernovae have shown evidence of the interaction between supernovae and the dense slow winds from the red supergiant progenitor stars. Observations of planetary nebulae and the nebula around SN 1987A show that the slow winds from extended stars frequently have an axisymmetric structure with a high density in the equatorial plane. We have carried out numerical calculations of the interaction of a supernova with such an axisymmetric density distribution. For small values of the angular density gradient at the pole, the asymmetry in the interaction shell is greater than, but close to, that expected from purely radial motion. If the angular density gradient is above a moderate value, then the flow qualitatively changes and a protrusion emerges along the axis. For a power-law supernova density profile, the flow approaches a self-similar state in which the protrusion length is 2–4 times the radius of the main shell. The critical density gradient is larger for steeper density profiles of the ejecta. Most of our calculations are axisymmetric, but we have carried out a three-dimensional calculation to show that the protrusion is not a numerical artifact along the symmetry axis. For typical supernova parameters, the protrusions take ≳ several years to develop. The appearance of the shell with protrusions is similar to that observed in VLBI radio images of the remnant 41.9+58 in M82 and possibly of SN 1986J. We also considered the possibility of asymmetric ejecta and found that it had a relatively small effect on the asymmetry of the interaction region. DA - 1996/11// PY - 1996/11// DO - 10.1086/178060 VL - 472 IS - 1 SP - 257-266 KW - circumstellar matter KW - hydrodynamics KW - ISM, structure KW - shock waves KW - supernova, remnants KW - supernovae, general ER - TY - JOUR TI - Self-consistent Bayesian analysis of space-time symmetry studies AU - Davis, E.D. T2 - Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment AB - We introduce a Bayesian method for the analysis of epithermal neutron transmission data on space-time symmetries in which unique assignment of the prior is achieved by maximisation of the cross entropy and the imposition of a self-consistency criterion. Unlike the maximum likelihood method used in previous analyses of parity-violation data, our method is freed of an ad hoc cutoff parameter. Monte Carlo studies indicate that our self-consistent Bayesian analysis is superior to the maximum likelihood method when applied to the small data samples typical of symmetry studies. DA - 1996/2// PY - 1996/2// DO - 10.1016/0168-9002(95)00802-0 VL - 370 IS - 2-3 SP - 509-515 J2 - Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment LA - en OP - SN - 0168-9002 UR - http://dx.doi.org/10.1016/0168-9002(95)00802-0 DB - Crossref ER - TY - JOUR TI - Structural mechanics of carbon nanotubes: From continuum elasticity to atomistic fracture AU - Yakobson, B. I. AU - Brabec, C. J. AU - Bernholc, J. T2 - Journal of Computer-Aided Materials Design DA - 1996/8// PY - 1996/8// DO - 10.1007/bf01185652 VL - 3 IS - 1-3 SP - 173-182 J2 - J Computer-Aided Mater Des LA - en OP - SN - 0928-1045 1573-4900 UR - http://dx.doi.org/10.1007/bf01185652 DB - Crossref ER - TY - JOUR TI - Doping Properties of Amphoteric C, Si, and Ge Impurities in GaN and AlN AU - Boguslawski, P. AU - Bernholc, J. T2 - Acta Physica Polonica A AB - Electronic structure of substitutional group-IV impurities C, Si, and Ge in hexagonal GaN and AlN were studied by quantum molecular dynamics.Cis is a very shallow acceptor, and thus a promising p-type dopant.Both Si and Ge are excellent donors in GaN.However, in AlGaN alJoys the DX configurations are stable for a sufficiently high Al content, which quenches the doping efficiency.Electronic structure of nearest-neighbor Χcatiοn-ΧΝ pairs is also discussed. DA - 1996/10// PY - 1996/10// DO - 10.12693/aphyspola.90.735 VL - 90 IS - 4 SP - 735-738 J2 - Acta Phys. Pol. A LA - en OP - SN - 0587-4246 1898-794X UR - http://dx.doi.org/10.12693/aphyspola.90.735 DB - Crossref ER - TY - JOUR TI - Theory of Defects, Doping, Surfaces and Interfaces in Wide Gap Nitrides AU - Bernholc, J. AU - Boguslawski, P. AU - Briggs, E. L. AU - Nardelli, M. Buongiorno AU - Chen, B. AU - Rapcewicz, K. AU - Zhang, Z. T2 - MRS Proceedings DA - 1996/// PY - 1996/// DO - 10.1557/proc-423-465 VL - 423 J2 - MRS Proc. LA - en OP - SN - 0272-9172 1946-4274 UR - http://dx.doi.org/10.1557/proc-423-465 DB - Crossref ER - TY - JOUR TI - Real-space multigrid-based approach to large-scale electronic structure calculations AU - Briggs, E. L. AU - Sullivan, D. J. AU - Bernholc, J. T2 - Physical Review B AB - We describe a set of techniques for performing large scale ab initio calculations using multigrid accelerations and a real-space grid as a basis. The multigrid methods provide effective convergence acceleration and preconditioning on all length scales, thereby permitting efficient calculations for ill-conditioned systems with long length scales or high energy cutoffs. We discuss specific implementations of multigrid and real-space algorithms for electronic structure calculations, including an efficient multigrid-accelerated solver for Kohn-Sham equations, compact yet accurate discretization schemes for the Kohn-Sham and Poisson equations, optimized pseudopotentials for real-space calculations, efficacious computation of ionic forces, and a complex-wave-function implementation for arbitrary sampling of the Brillouin zone. A particular strength of a real-space multigrid approach is its ready adaptability to massively parallel computer architectures, and we present an implementation for the Cray-T3D with essentially linear scaling of the execution time with the number of processors. The method has been applied to a variety of periodic and nonperiodic systems, including disordered Si, a N impurity in diamond, AlN in the wurtzite structure, and bulk Al. The high accuracy of the atomic forces allows for large step molecular dynamics; e.g., in a 1-ps simulation of Si at 1100 K with an ionic step of 80 a.u., the total energy was conserved within 27 \ensuremath{\mu}eV per atom. \textcopyright{} 1996 The American Physical Society. DA - 1996/11/15/ PY - 1996/11/15/ DO - 10.1103/physrevb.54.14362 VL - 54 IS - 20 SP - 14362-14375 J2 - Phys. Rev. B LA - en OP - SN - 0163-1829 1095-3795 UR - http://dx.doi.org/10.1103/physrevb.54.14362 DB - Crossref ER - TY - JOUR TI - Amphoteric properties of substitutional carbon impurity in GaN and AlN AU - Bogusl/awski, P. AU - Briggs, E. L. AU - Bernholc, J. T2 - Applied Physics Letters AB - Electronic structure and formation energies of substitutional carbon impurities in hexagonal GaN and AlN were studied by quantum molecular dynamics. Substitutions on both cation and anion sites were considered. Ccation is a shallow donor, while CN is a shallow acceptor. A DX-like configuration is metastable for CGa and CAl0, and stable for CAl−. The solubility of carbon is excellent, but it is accompanied by efficient self-compensation of carbon acceptors by carbon donors. This is due to two factors: (i) the large energy gain induced by electron transfer from Ccation to CN, which is close to the band gap energy, and (ii) the large binding energy (∼1 eV) of nearest neighbor Ccation+-CN− pairs. DA - 1996/7/8/ PY - 1996/7/8/ DO - 10.1063/1.117934 VL - 69 IS - 2 SP - 233-235 J2 - Appl. Phys. Lett. LA - en OP - SN - 0003-6951 1077-3118 UR - http://dx.doi.org/10.1063/1.117934 DB - Crossref ER - TY - JOUR TI - Theory of Interfaces in Wide-Gap Nitrides AU - Nardelli, M. Buongiorno AU - Rapcewicz, K. AU - Briggs, E. L. AU - Bungaro, C. AU - Bernholc, J. T2 - MRS Proceedings DA - 1996/// PY - 1996/// DO - 10.1557/proc-449-893 VL - 449 J2 - MRS Proc. LA - en OP - SN - 0272-9172 1946-4274 UR - http://dx.doi.org/10.1557/proc-449-893 DB - Crossref ER - TY - JOUR TI - Electric field suppression of epileptiform activity in hippocampal slices AU - Gluckman, B.J. AU - Neel, E.J. AU - Netoff, T.I. AU - Ditto, W.L. AU - Spano, M.L. AU - Schiff, S.J. T2 - Journal of Neurophysiology DA - 1996/// PY - 1996/// VL - 76 IS - 6 SP - 4202-4205 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-0030473481&partnerID=MN8TOARS ER - TY - JOUR TI - Controlling chaos in high dimensions: Theory and experiment AU - Ding, M. AU - Yang, W. AU - In, V. AU - Ditto, W.L. AU - Spano, M.L. AU - Gluckman, B. T2 - Physical Review E - Statistical Physics, Plasmas, Fluids, and Related Interdisciplinary Topics DA - 1996/// PY - 1996/// VL - 53 IS - 5 SUPPL. A SP - 4334-4344 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-0001158240&partnerID=MN8TOARS ER - TY - JOUR TI - Scaling laws for spatiotemporal synchronization and array enhanced stochastic resonance AU - Lindner, J.F. AU - Meadows, B.K. AU - Ditto, W.L. AU - Inchiosa, M.E. AU - Bulsara, A.R. T2 - Physical Review E - Statistical Physics, Plasmas, Fluids, and Related Interdisciplinary Topics DA - 1996/// PY - 1996/// VL - 53 IS - 3 SP - 2081-2086 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-4243891810&partnerID=MN8TOARS ER - TY - CONF TI - Novel mapping storage architecture enabling tens of thousands of channels on a personal computer platform AU - Witkowski, Francis X. AU - Penkoske, Patricia A. AU - Plonsey, Robert AU - Kavanagh, Katherine M. AU - Giles, Wayne R. AU - Spano, Mark L. AU - Ditto, William L. C2 - 1996/// C3 - Annual International Conference of the IEEE Engineering in Medicine and Biology - Proceedings DA - 1996/// VL - 5 SP - 1885-1886 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-0030316054&partnerID=MN8TOARS ER - TY - JOUR TI - Stochastic resonance in a neuronal network from mammalian brain AU - Gluckman, B.J. AU - Netoff, T.I. AU - Neel, E.J. AU - Ditto, W.L. AU - Spano, M.L. AU - Schiff, S.J. T2 - Physical Review Letters DA - 1996/// PY - 1996/// VL - 77 IS - 19 SP - 4098-4101 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-0000325573&partnerID=MN8TOARS ER - TY - JOUR TI - The Axial anomaly in QCD at finite temperature AU - Schäfer, Thomas T2 - Phys.Lett.B AB - We study flavor mixing and the U(1)A anomaly in QCD at zero and finite temperature. Using the instanton liquid model, we show that the strength of the anomaly is essentially unchanged near the critical temperature for chiral symmetry restoration. We demonstrate that nevertheless chiral symmetry restoration has important consequences for the η and η′. In particular, the strange and non-strange components of the η unmix near Tc. The anomaly does not affect the strange eta, so we expect a light purely strange pseudoscalar near the phase transition. DA - 1996/8// PY - 1996/8// DO - 10.1016/S0370-2693(96)01324-X VL - 389 SP - 445-451 UR - http://inspirehep.net/record/422347 ER - TY - JOUR TI - The Interacting instanton liquid in QCD at zero and finite temperature AU - Schäfer, Thomas AU - Shuryak, Edward V. T2 - Phys.Rev.D AB - In this paper we study the statistical mechanics of the instanton liquid in QCD. After introducing the partition function as well as the gauge-field- and quark-induced interactions between instantons, we describe a method to calculate the free energy of the instanton system. We use this method to determine the equilibrium density and the equation of state from numerical simulations of the instanton ensemble in QCD for various numbers of flavors. We find that there is a critical number of flavors above which chiral symmetry is restored in the ground state. In the physical case of two light and one intermediate mass flavors, the system undergoes a chiral phase transition at $T\ensuremath{\simeq}125$ MeV. We show that the mechanism for this transition is a rearrangement of the instanton liquid, going from a disordered, random phase at low temperatures to a strongly correlated, molecular phase at high temperature. We also study the behavior of mesonic susceptibilities near the phase transition. DA - 1996/9// PY - 1996/9// DO - 10.1103/PhysRevD.53.6522 VL - 53 SP - 6522-6542 UR - http://inspirehep.net/record/399602 ER - TY - CONF TI - Progress in instanton liquid calculations AU - Schäfer, Thomas C2 - 1996/9// C3 - 3rd AUP Workshop on QCD: Collisions, Confinement, and Chaos DA - 1996/9// SP - 333-339 UR - http://inspirehep.net/record/40668 ER - TY - CONF TI - The Chiral phase transition AU - Schäfer, Thomas AB - I review the current understanding of the chiral phase transition in QCD, with particular emphasis on recent results in the instanton liquid model. C2 - 1996/8// C3 - Nucl.Phys.A DA - 1996/8// DO - 10.1016/S0375-9474(96)00339-9 VL - 610 SP - 13C-25C UR - http://inspirehep.net/record/421765 ER - TY - JOUR TI - Hadronic correlation functions in the interacting instanton liquid AU - Schäfer, Thomas AU - Shuryak, Edward V. T2 - Phys.Rev.D AB - In this paper we study hadronic correlation functions in the interacting instanton liquid model, both at zero and nonzero temperature $T$. At zero $T$ we investigate the dependence of the correlators on the instanton ensemble, in particular, the effect of the fermionic determinant. We demonstrate that quark-induced correlations between instantons are important, especially in the repulsive ${\ensuremath{\eta}}^{\ensuremath{'}}$ and $\ensuremath{\delta}$-meson channels. We also calculate a large number of mesonic and baryonic correlation functions as a function of temperature. We find three different types of behavior as $T\ensuremath{\rightarrow}{T}_{c}$. The vector channels $\ensuremath{\rho}$, ${a}_{1}$, $\ensuremath{\Delta}$ show a gradual melting of the resonance contribution and approach free quark behavior near the chiral phase transition. The light pseudoscalars and scalars $\ensuremath{\pi}$, $\ensuremath{\sigma}$ as well as the nucleon show stable resonance contributions, probably even surviving above ${T}_{c}$. Correlation functions in the heavy scalar channels ${\ensuremath{\eta}}^{\ensuremath{'}}$, $\ensuremath{\delta}$ are enhanced as $T\ensuremath{\rightarrow}{T}_{c}$. DA - 1996/12// PY - 1996/12// DO - 10.1103/PhysRevD.54.1099 VL - 54 SP - 1099-1111 UR - http://inspirehep.net/record/403852 ER - TY - PAT TI - Electrodeless High Intensity Discharge Lamp Energized By A Rotating Electric Field AU - P, Lapatovich Walter AU - J, Butler Scott AU - R, Bochinski Jason C2 - 1996/3/12/ DA - 1996/3/12/ PY - 1996/3/12/ UR - https://www.lens.org/002-705-717-176-285 ER - TY - PAT TI - Leistungskompensierte Kopplungsanordnung Für Elektrodenlose Entladungslampe AU - J, Butler Scott AU - P, Lapatovich Walter AU - R, Bochinski Jason C2 - 1996/7/4/ DA - 1996/7/4/ PY - 1996/7/4/ UR - https://www.lens.org/028-484-308-795-939 ER - TY - PAT TI - Power Balanced Coupling Structure For Electrodeless Discharge Lamp AU - J, Butler Scott AU - P, Lapatovich Walter AU - R, Bochinski Jason C2 - 1996/5/29/ DA - 1996/5/29/ PY - 1996/5/29/ UR - https://www.lens.org/019-178-207-347-641 ER - TY - PAT TI - Method For Operating An Electrodeless Hid Lamp And An Electrodeless Lamp System AU - P, Lapatovich Walter AU - J, Butler Scott AU - R, Bochinski Jason AU - H, Goss Harold C2 - 1996/6/26/ DA - 1996/6/26/ PY - 1996/6/26/ UR - https://www.lens.org/000-275-939-290-155 ER - TY - PAT TI - Method For Deflecting The Arc Of An Electrodeless Hid Lamp AU - P, Lapatovich Walter AU - J, Butler Scott AU - R, Bochinski Jason AU - H, Goss Harold C2 - 1996/4/16/ DA - 1996/4/16/ PY - 1996/4/16/ UR - https://www.lens.org/184-474-432-156-920 ER - TY - JOUR TI - Nano-Raman spectroscopy and imaging with a near-field scanning optical microscope AU - Jahncke, C.L. AU - Hallen, H.D. AU - Paesler, M.A. T2 - J. Raman Spectrosc. AB - Raman spectroscopy was performed using a near-field scanning optical microscope. This avoids the diffraction limit inherent in conventional optical microscopy techniques involving far-field optical components, and allows volumes significantly smaller than the cube of the wavelength to be investigated. The small sample volume coupled with the light-starved nature of the Raman effect itself makes such nano-Raman studies difficult. A near-field Raman microscope is described and results showing near-field effects in an investigation of Rb-doped KTP are presented. An image taken within a Raman feature demonstrates that nano-Raman imaging is indeed possible if the near-field instrument has considerable long-term stability, and that several unique aspects of the near-field data recommend this approach. DA - 1996/8// PY - 1996/8// DO - 10.1002/(SICI)1097-4555(199608)27:8<579::AID-JRS13>3.0.CO;2-4 VL - 27 IS - 8 SP - 579 - 86 N1 - – An invited paper RN - – An invited paper ER - TY - JOUR TI - Penetration of laterally quantized flux lamina into a superconducting wire network AU - Hallen, H.D. AU - Chang, A.M. AU - Miller, R. AU - Pfeiffer, L.N. AU - West, K. AU - Hess, H.F. T2 - Solid State Communications AB - Abstract We report direct, high resolution images of the magnetic field above a superconducting wire grid as applied flux penetrates into an initially empty state or into a state with half the plaquettes containing a magnetic quantum. We find two qualitatively different initial approaches to equilibrium: in wide structures for the former, or with long, linear structures for the latter case. In the approach to an empty state, we observe the formation of residual quasi-bound magnetic vortex/anti-vortex pairs. DA - 1996/// PY - 1996/// DO - 10.1016/0038-1098(96)00123-8 VL - 99 IS - 9 SP - 651 - 654 UR - http://dx.doi.org/10.1016/0038-1098(96)00123-8 KW - superconductors KW - scanning probe microscopy KW - flux pinning and creep ER - TY - CONF TI - Near-field Raman spectra: Surface enhancement, z-polarization, fiber Raman background and Rayleigh scattering AU - Jahncke, C.L. AU - Hallen, H.D. AB - Near-field optical microscopy (NSOM) is a technique that offers several advantages over conventional optical microscopy. We present evidence for a z-polarization component and a surface-enhancement effect in near-field Raman data. Observation of Raman scattering from the fiber probe and Rayleigh scattering may be used to determine probe quality. The sample studied is KTiOPO/sub 4/ (KTP) a nonlinear optical material, for which a comparison of near-field and far-field spectra is shown. C2 - 1996/// C3 - Conference Proceedings - Lasers and Electro-Optics Society Annual Meeting-LEOS CY - Boston, MA, USA DA - 1996/// DO - 10.1109/LEOS.1996.565182 VL - 1 SP - 176 - 177 UR - https://doi.org/10.1109/LEOS.1996.565182 ER - TY - CONF TI - Imaging of silicon carrier dynamics with near-field scanning optical microscopy AU - La Rosa, A.H. AU - Yakobson, B.I. AU - Hallen, H.D. C2 - 1996/// C3 - Materials Research Society Symposium - Proceedings CY - Boston, MA, USA DA - 1996/// DO - 10.1557/PROC-406-189 VL - 406 SP - 189 - 194 UR - https://doi.org/10.1557/PROC-406-189 ER - TY - JOUR TI - Test of Parity-Conserving Time-Reversal Invariance Using Polarized Neutrons and Nuclear Spin Aligned Holmium AU - Huffman, P. R. AU - Roberson, N. R. AU - Wilburn, W. S. AU - Gould, C. R. AU - Haase, D. G. AU - Keith, C. D. AU - Raichle, B. W. AU - Seely, M. L. AU - Walston, J. R. T2 - Physical Review Letters AB - A test of parity-conserving, time-reversal noninvariance (PC TRNI) has been performed in 5.9 MeV polarized neutron transmission through nuclear spin aligned holmium. The experiment searches for the T-violating fivefold correlation via a double modulation technique---flipping the neutron spin while rotating the alignment axis of the holmium. Relative cross sections for spin-up and spin-down neutrons are found to be equal to within $1.2\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}5}$ (80% confidence). This is a 2 orders of magnitude improvement compared to traditional detailed balance studies of time reversal, and represents the most precise test of PC TRNI in a dynamical process. DA - 1996/6/17/ PY - 1996/6/17/ DO - 10.1103/physrevlett.76.4681 VL - 76 IS - 25 SP - 4681-4684 J2 - Phys. Rev. Lett. LA - en OP - SN - 0031-9007 1079-7114 UR - http://dx.doi.org/10.1103/physrevlett.76.4681 DB - Crossref ER - TY - JOUR TI - Neutron resonances in 165-Holmium AU - Huffman, P. R. AU - Frankle, C. M. AU - Gould, C. R. AU - Haase, D. G. AU - Harvey, J. A. AU - Roberson, N. R. AU - Weston, L. W. T2 - Physical Review C AB - We report the results of a high-resolution study of neutron resonances below 500 eV in $^{166}\mathrm{Ho}$. We find nine previously unreported weak resonances at energies 24.79, 75.08, 119.98, 187.94, 210.86, 227.87, 235.94, 248.60, and 264.98 eV. Bayesian probability analysis of the widths indicates they are formed primarily by s-wave capture and are therefore negative-parity resonances. If they have measurable d-wave neutron widths, they are candidates for the fivefold correlation test of time reversal. \textcopyright{} 1996 The American Physical Society. DA - 1996/10/1/ PY - 1996/10/1/ DO - 10.1103/physrevc.54.2051 VL - 54 IS - 4 SP - 2051–2054 SN - 0556-2813 1089-490X UR - http://dx.doi.org/10.1103/physrevc.54.2051 ER - TY - JOUR TI - Measurements of the total cross section for the scattering of polarized neutrons from Polarized 3He AU - Keith, C. D. AU - Gould, C. R. AU - Haase, D. G. AU - Seely, M. L. AU - Huffman, P. R. AU - Roberson, N. R. AU - Tornow, W. AU - Wilburn, W. S. T2 - Physical Review C AB - Measurements of polarized neutron--polarized $^3$He scattering are reported. The target consisted of cryogenically-polarized solid $^3$He, thickness 0.04 atom/b and polarization 40%. The longitudinal and transverse total cross-section differences $\Delta\sigma_L$ and $\Delta\sigma_T$ were measured for incident neutron energies 2-8 MeV. The results are compared to phase-shift predictions based on four different analyses of n-$^3$He scattering. The best agreement is obtained with a recent R-matrix analysis of A=4 scattering and reaction data, lending strong suport to the $^4$He level scheme obtained in that analysis. DA - 1996/8/1/ PY - 1996/8/1/ DO - 10.1103/physrevc.54.477 VL - 54 IS - 2 SP - 477–486 SN - 0556-2813 1089-490X UR - http://dx.doi.org/10.1103/physrevc.54.477 ER - TY - PAT TI - Methods for monitoring and controlling deposition and etching using p-polarized reflectance spectroscopy AU - Bachmann, K. J. AU - Dietz, N. AU - Miller, A. E. C2 - 1996/// DA - 1996/// PY - 1996/// ER - TY - JOUR TI - Monte Carlo simulation and reference hypernetted chain equation results for structural, thermodynamic, and dielectric properties of polar heteronuclear diatomic fluids AU - Lombardero, M AU - Martin, C AU - Lomba, E AU - Lado, F T2 - JOURNAL OF CHEMICAL PHYSICS AB - We study fluids of heteronuclear two-center Lennard-Jones molecules with embedded point dipoles using both numerical simulation and integral equation theory. Extensive Monte Carlo simulations are performed for the structural, thermodynamic, and dielectric properties of two models of such fluids, with unusually long simulation runs to assure convergence of the dielectric constant. The results are used to test a generalization of a reference hypernetted chain approximation (RHNC-VM) used previously for nonpolar heteronuclear diatomics. Very good agreement is found between the two methods. We conclude that the RHNC-VM integral equation is a reliable method for studying both polar and nonpolar fluids of diatomic molecules. DA - 1996/5/1/ PY - 1996/5/1/ DO - 10.1063/1.471388 VL - 104 IS - 17 SP - 6710-6718 SN - 0021-9606 ER - TY - JOUR TI - Integral equation theory of polydisperse colloidal suspensions using orthogonal polynomial expansions AU - Lado, F T2 - PHYSICAL REVIEW E AB - A procedure is described for the calculation of the generalized pair distribution function g(r,\ensuremath{\sigma},${\mathrm{\ensuremath{\sigma}}}^{\ensuremath{'}}$), where \ensuremath{\sigma} is a molecular random variable with distribution f(\ensuremath{\sigma}), using generalized integral equations familiar from simple liquid theory. The method is based on expansions of all \ensuremath{\sigma}-dependent functions in the orthogonal polynomials ${\mathit{p}}_{\mathit{j}}$(\ensuremath{\sigma}) associated with the weight f(\ensuremath{\sigma}) and is computationally efficient. To illustrate the procedure, calculations are made for a charge-stabilized, polydisperse colloidal suspension with Schulz distribution of diameters \ensuremath{\sigma}. The method can be immediately generalized to fluids with internal degrees of freedom, for whichf(\ensuremath{\sigma}) must itself be self-consistently determined. \textcopyright{} 1996 The American Physical Society. DA - 1996/10// PY - 1996/10// DO - 10.1103/physreve.54.4411 VL - 54 IS - 4 SP - 4411-4419 SN - 1063-651X ER - TY - JOUR TI - The impact of video motion analysis on kinematics graph interpretation skills AU - Beichner, RJ T2 - AMERICAN JOURNAL OF PHYSICS AB - Video motion analysis software was used by introductory physics students in a variety of instructional settings. 368 high school and college students took part in a study where the effect of graduated variations in the use of a video analysis tool was examined. Post-instruction assessment of student ability to interpret kinematics graphs indicates that groups using the tool generally performed better than students taught via traditional instruction. The data further establishes that the greater the integration of video analysis into the kinematics curriculum, the larger the educational impact. An additional comparison showed that graph interpretation skills were significantly better when a few traditional labs were simply replaced with video analysis experiments. Hands-on involvement appeared to play a critical role. Limiting student experience with the video analysis technique to a single teacher-led demonstration resulted in no improvement in performance relative to traditional instruction. Offering more extensive demonstrations and carrying them out over an extended period of time proved somewhat effective. The greatest impact came from a combination of demonstrations with hands-on labs. The curricular modifications employed in the different classrooms and the methods used to evaluate them are discussed. DA - 1996/10// PY - 1996/10// DO - 10.1119/1.18390 VL - 64 IS - 10 SP - 1272-1277 SN - 0002-9505 ER - TY - JOUR TI - Relativistic material reference systems AU - Brown, JD AU - Marolf, D T2 - PHYSICAL REVIEW D AB - This work closes certain gaps in the literature on material reference systems in general relativity. It is shown that perfect fluids are a special case of DeWitt's relativistic elastic media and that the velocity-potential formalism for perfect fluids can be interpreted as describing a perfect fluid coupled to a fleet of clocks. A Hamiltonian analysis of the elastic media with clocks is carried out and the constraints that arise when the system is coupled to gravity are studied. When the Hamiltonian constraint is resolved with respect to the clock momentum, the resulting true Hamiltonian is found to be a functional only of the gravitational variables. The true Hamiltonian is explicitly displayed when the medium is dust, and is shown to depend on the detailed construction of the clocks. \textcopyright{} 1996 The American Physical Society. DA - 1996/2/15/ PY - 1996/2/15/ DO - 10.1103/physrevd.53.1835 VL - 53 IS - 4 SP - 1835-1844 SN - 0556-2821 UR - http://inspirehep.net/record/399454 ER - TY - JOUR TI - On variational principles for gravitating perfect fluids AU - Brown, J. D. T2 - Annals of Physics AB - The connection is established between two different action principles for perfect fluids in the context of general relativity. For one of these actions,S, the fluid four–velocity is expressed as a sum of products of scalar fields and their gradients (the velocity–potential representation). For the other action,S, the fluid four–velocity is proportional to the totally antisymmetric product of gradients of the fluid Lagrangian coordinates. The relationship betweenSandSis established by expressingSin Hamiltonian form and identifying certain canonical coordinates as ignorable. Elimination of these coordinates and their conjugates yields the actionS. The key step in the analysis is a point canonical transformation in which all tensor fields on space are expressed in terms of the Lagrangian coordinate system supplied by the fluid. The canonical transformation is of interest in its own right. It can be applied to any physical system that includes a material medium described by Lagrangian coordinates. The result is a Hamiltonian description of the system in which the momentum constraint is trivial. DA - 1996/// PY - 1996/// DO - 10.1006/aphy.1996.0049 VL - 248 SP - 1–33 ER - TY - JOUR TI - Nanomechanics of carbon tubes: Instabilities beyond linear response AU - Yakobson, BI AU - Brabec, CJ AU - Bernholc, J T2 - PHYSICAL REVIEW LETTERS AB - Carbon nanotubes subject to large deformations reversibly switch into different morphological patterns. Each shape change corresponds to an abrupt release of energy and a singularity in the stress-strain curve. These transformations, simulated using a realistic many-body potential, are explained by a continuum shell model. With properly chosen parameters, the model provides a remarkably accurate ``roadmap'' of nanotube behavior beyond Hooke's law. DA - 1996/4/1/ PY - 1996/4/1/ DO - 10.1103/PhysRevLett.76.2511 VL - 76 IS - 14 SP - 2511-2514 SN - 0031-9007 ER - TY - JOUR TI - Structural flexibility of carbon nanotubes AU - Iijima, S AU - Brabec, C AU - Maiti, A AU - Bernholc, J T2 - JOURNAL OF CHEMICAL PHYSICS AB - We report high resolution electron microscope (HREM) observations and atomistic simulations of the bending of single and multi-walled carbon nanotubes under mechanical duress. Single and multiple kinks are observed at high bending angles. Their occurrence is quantitatively explained by the simulations, which use a realistic many-body potential for the carbon atoms. We show that the bending is fully reversible up to very large bending angles, despite the occurrence of kinks and highly strained tube regions. This is due to the remarkable flexibility of the hexagonal network, which resists bond breaking and bond switching up to very high strain values. DA - 1996/2/1/ PY - 1996/2/1/ DO - 10.1063/1.470966 VL - 104 IS - 5 SP - 2089-2092 SN - 0021-9606 ER - TY - CHAP TI - Stimulated emission and gain measurements from InGaN/GaN heterostructures AU - Shmagin, I. K. AU - Muth, J. F. AU - Kolbas, R. M. AU - Krishnankkutty, S. AU - Keller, S. AU - Mishra, U. K. AU - DenBaars, S. P. T2 - III-V nitrides: Symposium held December 2-6, 1996, Boston, Massachusetts, U.S.A.(Materials Research Society symposia proceedings ; v. 449) CN - QC176.9 .M84 A14 1997 PY - 1996/// SP - 1209-1214 PB - Pittsburgh, Pa.: Materials Research Society ER - TY - CHAP TI - Quantum well heterostructure lasers AU - Kolbas, R. M. T2 - Properties of gallium arsenide (3rd ed.) (Datareviews series, no. 16) A2 - M. R. Brozel, A2 - Stillman, G. E. CN - TK7871.15.G3 P76 1996 PY - 1996/// SP - 887-905 PB - INSPEC ER - TY - CONF TI - Growth of bulk AIN and GaN single crystals by sublimation AU - Balkas, C. M. AU - Sitar, Z. AU - Zheleva, T. AU - Bergman, L. AU - Shmagin, I. K. AU - Muth, J. F. AU - Kolbas, R. M. AU - Nemanich, R. AU - Davis, R. F. C2 - 1996/// C3 - III-V nitrides: symposium held December 2-6, 1996, Boston, Massachusetts, U.S.A. (Materials Research Society symposia proceedings ; v. 449) CN - QC176.9 .M84 A14 1997 DA - 1996/// SP - 41-46 PB - Pittsburgh, Pa.: Materials Research Society ER -