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Articles 34321 - 34350 of 36545

Full-Text Articles in Physical Sciences and Mathematics

The Pauli Operator Correction In The Effective Λn Interaction, Jaleh Owliaei Apr 1985

The Pauli Operator Correction In The Effective Λn Interaction, Jaleh Owliaei

Masters Theses

Hypernuclear structure calculations performed for 6ΛLi, 7ΛLi, and 16Λ0 have reproduced the 1Λ=1 levels inferred from the recent (k, Π) reactions. However the 1Λ=0, groundstate of 16Λ0 is overbound by 6 MeV in these calculations, indicating a density dependence in the effective ΛN interaction in the interior of the heavier system. In this work corrections to the 16Λ0 effective interaction are introduced in terms of a Brueckner-Goldstone G-matrix with a modified Pauli operator. The G-matrix of 16Λ0 derived from that of 6ΛLi …

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Resonant Electron Transfer And K-Shell Excitation Of Lithiumlike Projectiles In Collisions With Neutral Gas Targets, Carollyn Sloan Oglesby Apr 1985

Resonant Electron Transfer And K-Shell Excitation Of Lithiumlike Projectiles In Collisions With Neutral Gas Targets, Carollyn Sloan Oglesby

Masters Theses

No abstract provided.

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Problems Of Channel Correlation And Statistical Bias In Photon-Correlation Spectroscopy, Richard C. Haskell, Gary L. Pisciotta Apr 1985

Problems Of Channel Correlation And Statistical Bias In Photon-Correlation Spectroscopy, Richard C. Haskell, Gary L. Pisciotta

All HMC Faculty Publications and Research

Correlation between channels of the normalized photocount-rate correlation function g(2)(τ) becomes significant at high count rates and leads to a number of data-analysis problems. We derive an expression for channel correlation that is valid for a detector area of arbitrary extent and compare the theoretical predictions with measured values. A data-analysis procedure is demonstrated that employs the theoretical expression for channel correlation and provides a rigorous test of an assumed fitting function. The procedure facilitates the use of the cumulant method in determining the polydispersity of scatterers. An expression for the statistical bias of g(2) …

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Small-Angle Neutron Scattering Of (Er₀.₈Ho₀.₂)Rh₄B₄, Oran Allan Pringle, Herbert A. Mook, M. Brian Maple Apr 1985

Small-Angle Neutron Scattering Of (Er₀.₈Ho₀.₂)Rh₄B₄, Oran Allan Pringle, Herbert A. Mook, M. Brian Maple

Physics Faculty Research & Creative Works

The (Er1-xHox)Rh4B4 pseudoternary alloy system has a minimum in the phase boundary between the superconducting and ferromagnetic phases near x=0.3. This minimum has been identified as due to the competing magnetic anisotropies of Er and Ho. It has also been suggested that there could be a Lifschitz point near the minimum. Using the 30-m SANS camera at the National Center for Small-Angle Scattering Research at ORNL, we have observed a peak in the SANS pattern for (Er 0.8Ho0.2)Rh4B4 at Q=0.065 Å-1. This peak appears for …

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Lung Cancer Incidence In A Chinese High Background Area — Epidemiological Results And Theoretical Interpretation, Werner Hofmann, Robert Katz, Chunxiang Zhang Mar 1985

Lung Cancer Incidence In A Chinese High Background Area — Epidemiological Results And Theoretical Interpretation, Werner Hofmann, Robert Katz, Chunxiang Zhang

Robert Katz Publications

A survey of inhabitant exposures arising from the inhalation of radon and thoron daughters, and lung cancer mortality has been carried out in two adjacent areas in Guangdong province, China, designated as the "high background" and the "control" area. Annual exposure rates are 0.38 WLM/yr in the high background, and 0.16 WLM/yr in the control area, while age-adjusted mortality rates are 2.7 per 105 living people of all ages in the high background, and 2.9 per 105 in the control area. From this data we conclude that we are unable to determine the excess lung cancer rate over normal fluctuations …

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Self-Consistent Phases In Topological Particle Theory, Paul Finkler, C. Edward Jones Mar 1985

Self-Consistent Phases In Topological Particle Theory, Paul Finkler, C. Edward Jones

Paul Finkler Papers

To be a self-contained theory, topological particle theory should explain from the basis of its own stated framework of assumptions (nonlinear self-consistency equations, pole factorization, crossing symmetry, and Hermitian analyticity} all the mathematical properties and numerical values of scattering amplitudes. This paper attempts to move the theory in this direction by showing that the phases of the zero-entropy amplitudes in the theory are, in fact, determined by the above framework of assumptions except for trivial ambiguities that appear to have no physical consequences. This extends previous work on this subject and removes the need for certain extra assumptions. Once the …

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Derivation Of Discrete Invariances (T, C, And P) And The Connection Between Spin And Statistics In Topological Particle Theory, C. E. Jones, Paul Finkler Mar 1985

Derivation Of Discrete Invariances (T, C, And P) And The Connection Between Spin And Statistics In Topological Particle Theory, C. E. Jones, Paul Finkler

Paul Finkler Papers

For purely hadronic processes, the standard connection between spin and statistics as well as separate invariances under charge conjugation, parity, and time reversal are shown to be consequences of self-consistency in topological particle theory.

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Random-Field Critical Behavior And The Ginzburg Criterion, Miron Kaufman, Mehran Kardar Mar 1985

Random-Field Critical Behavior And The Ginzburg Criterion, Miron Kaufman, Mehran Kardar

Miron Kaufman

The Ginzburg criterion for crossover from classical to nonclassical critical behavior is derived in the presence of random fields. Experiments on dilute antiferromagnets in a field are examined, and the possibility of such a crossover is investigated. We also point out that the (necessarily) symmetric logarithmic divergence observed in birefringence measurements can be accompanied by a discontinuity, and a fitting form which allows for this and other corrections to scaling is proposed.

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Explicit Equations For The Polarizing Angles Of A High-Reflectance Substrate Coated By A Transparent Thin Film, R. M.A. Azzam Mar 1985

Explicit Equations For The Polarizing Angles Of A High-Reflectance Substrate Coated By A Transparent Thin Film, R. M.A. Azzam

Electrical Engineering Faculty Publications

Simple explicit equations are derived that determine the angles of incidence at which the parallel and perpendicular polarization components of light are extinguished on reflection from a transparent film coating a high-reflectance (metallic) substrate. The polarizing angles obtained from our approximate expressions are in excellent agreement with those determined by iterative numerical solution of the exact nonlinear equations that govern such angles. For the approximation to be valid, the intensity reflectance of the film-substrate interface, evaluated at the critical angle of the film-ambient interface, must exceed 0.5.

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Summary Abstract: Capacitance-Voltage Characteristics In Modulation Doped Heterojunction Fets, George B. Norris, David C. Look, W. Koop, J. Klem, H. Morkoç Mar 1985

Summary Abstract: Capacitance-Voltage Characteristics In Modulation Doped Heterojunction Fets, George B. Norris, David C. Look, W. Koop, J. Klem, H. Morkoç

Physics Faculty Publications

No abstract provided.

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Photoemission, Electronic Structure, And Magnetism In Vpd3, D.K. Misemer, S. Auluck, David J. Sellmyer, Sitaram Jaswal, A.J. Arko Mar 1985

Photoemission, Electronic Structure, And Magnetism In Vpd3, D.K. Misemer, S. Auluck, David J. Sellmyer, Sitaram Jaswal, A.J. Arko

David Sellmyer Publications

Electronic and magnetic states in the ordered compound VPd3 have been investigated with photoemission measurements and self-consistent band-structure calculations. The linear combination of muffin-tin orbitals method was used to study VPd3 in a hypothetical cubic crystal structure and the actual tetragonal crystal structure, and the calculations were performed for both paramagnetic and spin-polarized configurations. The results for the cubic structure are in agreement with earlier calculations, while the results from the tetragonal structure are in much better agreement with the photoemission and other measurements.

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A Birefringence Relaxation Determination Of Rotational Diffusion Of Magnetotactic Bacteria, Charles Rosenblatt, Richard B. Frankel, Richard P. Blakemore Mar 1985

A Birefringence Relaxation Determination Of Rotational Diffusion Of Magnetotactic Bacteria, Charles Rosenblatt, Richard B. Frankel, Richard P. Blakemore

Physics

The orientational relaxation of the magnetotactic bacterium Aquaspirillum magnetotacticum is observed by the decay of the optical birefringence upon switching off an aligning magnetic field. The data yield a rotational diffusion constant Dr ≅ 0.13 s1 and information about cell sizes that is consistent with optical microscopy data.

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Safety Evaluation Report Related To The Renewal Of The Operating License For The Triga Training And Research Reactor At The University Of Utah, United States Nuclear Regulatory Commission, Office Of Nuclear Reactor Regulations Mar 1985

Safety Evaluation Report Related To The Renewal Of The Operating License For The Triga Training And Research Reactor At The University Of Utah, United States Nuclear Regulatory Commission, Office Of Nuclear Reactor Regulations

Radioactive Materials

This Safety Evaluation Report for the application filed by the University of Utah (UU) for a renewal of operating license R-126 to continue to operate a training and research reactor facility has been prepared by the Office of Nuclear Reactor Regulation of the U.S. Nuclear Regulatory Commission. The facility is owned and operated by the University of Utah and is located on its campus in Salt Lake City, Salt Lake County, Utah. The staff concludes that this training reactor facility can continue to be operated by UU without endangering the health and safety of the public.

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Electron Doubly Differential Cross Section For 0.5-Mev H--He Detachment Collisions, Chang-Hwan Park, Anthony F. Starace, Joseph Macek Mar 1985

Electron Doubly Differential Cross Section For 0.5-Mev H--He Detachment Collisions, Chang-Hwan Park, Anthony F. Starace, Joseph Macek

Anthony F. Starace Publications

A comprehensive theoretical treatment is presented for the electron detachment cross section, differential in both electron momentum and direction, for collisions of 0.5-MeV H- projectiles on He targets. Our calculation, which assumes that the residual H atom is left in the 1s state, employs the usual first Born approximation as well as the closure approximation (in order to sum over all He target final states). Electron correlations within the H- system are treated in detail within the framework of the adiabatic hyperspherical coordinate approximation. In particular, for the first time for this collision process, angular correlations are included. The …

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Antireflecting And Polarizing Transparent Bilayer Coatings On Absorbing Substrates At Oblique Incidence, R. M.A. Azzam, Karim Javily Feb 1985

Antireflecting And Polarizing Transparent Bilayer Coatings On Absorbing Substrates At Oblique Incidence, R. M.A. Azzam, Karim Javily

Electrical Engineering Faculty Publications

The condition of zero reflection of p- and s-polarized light by a transparent bilayer on an absorbing substrate is derived in the form |gν(ø,Ni)| ≤ 1, where gν is a function of the angle of incidence ø, the refractive indices Ni(i = 0,1,2,3) of the system, and the polarization state ν (= p or s). As an application, the air-Si3N4-SiO2-Si system is considered at two laser wavelengths λ = 6328 and 3250 Å. The thicknesses of the two films of the bilayer and the …

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Single-Layer Antireflection Coatings On Absorbing Substrates For The Parallel And Perpendicular Polarizations At Oblique Incidence, R. M.A. Azzam Feb 1985

Single-Layer Antireflection Coatings On Absorbing Substrates For The Parallel And Perpendicular Polarizations At Oblique Incidence, R. M.A. Azzam

Electrical Engineering Faculty Publications

Explicit equations are derived that determine the refractive index of a single layer that suppresses the reflection of p- or s-polarized light from the planar interface between a transparent and an absorbing medium at any given angle of incidence. The required layer thickness and the system reflectance for the orthogonal unextinguished polarization also follow explicitly. This generalizes earlier work that was limited to normal incidence or to oblique incidence at dielectric—dielectric interfaces. Specific examples are given of p- and s-antireflection layers on Si and Al substrates at λ = 6328 Å at various angles of incidence.

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The Hydrogen Line Spectra Of Narrow-Line Radio Galaxies, Gary J. Ferland, Donald E. Osterbrock Feb 1985

The Hydrogen Line Spectra Of Narrow-Line Radio Galaxies, Gary J. Ferland, Donald E. Osterbrock

Physics and Astronomy Faculty Publications

We report the results of the first detection of Lyα in a narrow-line radio galaxy. Nearly simultaneous optical and UV observations of 3C 192 and 3C 223 allow the measurement of both Balmer and Lyman decrements. These line ratios are approximate functions of the interstellar reddening and of a parameter which is proportional to the amount of H I collisional excitation present. The reddening of 3C 192 is slightly larger than that due to our Galaxy, although 3C 223 may have a larger value. Both galaxies have intrinsic Balmer and Lyman decrements which are significantly steeper than case B, …

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Extinction Of The P And S Polarizations Of A Wave On Reflection At The Same Angle From A Transparent Film On An Absorbing Substrate: Applications To Parallel-Mirror Crossed Polarizers And A Novel Integrated Polarimeter, R. M.A. Azzam Feb 1985

Extinction Of The P And S Polarizations Of A Wave On Reflection At The Same Angle From A Transparent Film On An Absorbing Substrate: Applications To Parallel-Mirror Crossed Polarizers And A Novel Integrated Polarimeter, R. M.A. Azzam

Electrical Engineering Faculty Publications

The p- and s-polarized components of light can be suppressed on reflection at the same angle of incidence from an absorbing substrate coated by a transparent thin film if the wave is refracted in the film at 45° and the constraint Re[(ε2 - α)/(l -α)]1/2 = α + | ε2 - α| is satisfied, where 2α and ε2 are the ratios of dielectric constants of the film and substrate, respectively, to that of the ambient. For high-reflectance metal substrates (|ε2| » 1), α≈ 1, the ratio of film to ambient refractive index …

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Example Of A Group Action Determined Phase Transition, Jeffrey W. Felix, Dorian M. Hatch Feb 1985

Example Of A Group Action Determined Phase Transition, Jeffrey W. Felix, Dorian M. Hatch

Faculty Publications

The principles of the group action approach to structural phase transitions are outlined. It is assumed that all properties of the transition are determined by the action of a single physically irreducible represention of the space group of the more symmetric phase. We determine the isotropy groups using the image space of the representation. The free energy minima are determined to fourth order and to all orders using the results of Gufan and then compared. This theory is applied to Calcite (Roverline3c) to determine all possible continuous commensurate phase transitions.

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Schottky-Barrier Profiling Techniques In Semiconductors - Gate Current And Parasitic Resistance Effects, David C. Look Jan 1985

Schottky-Barrier Profiling Techniques In Semiconductors - Gate Current And Parasitic Resistance Effects, David C. Look

Physics Faculty Publications

The theory for obtaining mobility and carrier concentration profiles by the Hall-effect, magnetoresistance, and capacitance-conductance methods is developed in the relaxation-time approximation. This theory is then applied to semiconductors in which a Schottky barrier is used to control a depletion region. Particular emphasis is given to field-effect transistor structures which are ideally suited for geometric magnetoresistance measurements. A unique feature of the present model is the correction for finite gate (Schottky-barrier) current, which can be very important under forward-gate-bias conditions. The ability to use forward-bias makes the near-surface region more accessible. Also, parasitic resistance effects are treated. We apply these …

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Qcd Vacuum As A Chromomagnetic Superconductor: Microscopic Physics, V. Parameswaran Nair, C. Rosenzweig Jan 1985

Qcd Vacuum As A Chromomagnetic Superconductor: Microscopic Physics, V. Parameswaran Nair, C. Rosenzweig

Publications and Research

The compactness of the QCD gauge group leads to the existence of chromomagnetic monopole configurations. The interactions of these monopoles are studied using electric-magnetic duality as a guide. It is shown that the gluon-monopole interaction acquires an extra minus sign which tends to destabilize the monopole configurations. A model is presented which exploits this observation. We present a scenario where the monopoles condense, giving chromomagnetic superconductivity, via a first-order phase transition at a scale where the electric and magnetic charges are equal, i.e., α = 1/2 . In this vacuum medium gluons propagate like 1/k4 which is now seen …

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New Shubnikov-De Haas Effects In A Two-Dimensional Electron-Hole System, S. Washburn, Richard A. Webb, E. E. Mendez, L. L. Chang, L. Esaki Jan 1985

New Shubnikov-De Haas Effects In A Two-Dimensional Electron-Hole System, S. Washburn, Richard A. Webb, E. E. Mendez, L. L. Chang, L. Esaki

Faculty Publications

We report the temperature dependence of the Shubnikov–de Haas oscillations from a two-dimensional electron-hole system in GaSb-InAs-GaSb quantum wells at very low temperatures. The samples are double heterostructures containing separate electron and hole layers. The oscillations arising from the electron layer behave regularly with temperature. Additional oscillations, characterized by strong temperature dependence, and relatively large peak widths are believed to arise from the presence of hole layers.

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Two-Electron Qed Corrections In Helium-Like Ions, Gordon W. F. Drake, A. J. Makowski Jan 1985

Two-Electron Qed Corrections In Helium-Like Ions, Gordon W. F. Drake, A. J. Makowski

Physics Publications

The calculation of two-electron QED energy shifts in helium-like ions is discussed in order to correct a number of errors and misunderstandings which have appeared in the literature. New results are presented for the terms involving (r12-3) in the ground and low-lying excited states for ions up to Z=10. A detailed comparison is made with the high-precision measurement by Martin (1984) and a calculation by Hata (1984) for the 1s2p 1P1-1s2p 3P1 transition of helium.

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Lamb Shifts And Fine-Structure Splittings For The Muonic Ions - Li, - Be, And - B: A Proposed Experiment, Gordon W. F. Drake, L. L. Byer Jan 1985

Lamb Shifts And Fine-Structure Splittings For The Muonic Ions - Li, - Be, And - B: A Proposed Experiment, Gordon W. F. Drake, L. L. Byer

Physics Publications

Detailed calculations are presented for the energy splittings of the states 2s1/2-2p1/2 and 2s1/2-2p3/2 for the muonic ions - Li, - Be, and - B obtained by numerical integration of the Dirac equation. It is shown that there is severe cancellation between the vacuum polarization and finite nuclear size contributions to the energy differences, leading to transition frequencies which lie in the visible region of the spectrum. As a consequence of the cancellation, a measurement of the transition frequency would provide a sensitive probe of nuclear size and structure. The system - 7Li appears to offer particularly good possibilities for …

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Charge-Exchange Processes Of Hydrogen Ions With Hg Atoms At Kev Energies, A. Van Wijngaarden, J. Patel, K. Becker, Gordon W. F. Drake Jan 1985

Charge-Exchange Processes Of Hydrogen Ions With Hg Atoms At Kev Energies, A. Van Wijngaarden, J. Patel, K. Becker, Gordon W. F. Drake

Physics Publications

A search for the production of the 2p2 3Pe state of H- has been made by crossing a H-(1s2) ion beam of energies E<140 keV with a thermal Hg beam inside a static electric field. The formation of>H-(2p2) ions and their subsequent decay to neutral H(1s) results in a feature on the angular distribution of the neutral particles produced in electron loss of the ground-state H-(1s2) ions. The absence of such a feature sets an upper limit of 10-20 cm2 to the cross section for formation of the 2p2 3Pe state. Differential (with respect to angle) charge-transfer cross sections for scattering in the angular range 3°<<15°as well as the small-angle forward cross sections 10 and -10 for hydrogen ions passing through Hg vapor are presented. © 1985 The American Physical Society.

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Solution Of The Kondo Problem By Diagrammatic Methods, S. E. Barnes Jan 1985

Solution Of The Kondo Problem By Diagrammatic Methods, S. E. Barnes

Physics Articles and Papers

A self-consistent parquet approximation is shown to give exact results for the Kondo problem in the scaling limit.

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Mossbauer Spectroscopy Of Iron Biomineralization Products In Magnetotactic Bacteria, Richard B. Frankel, Georgia C. Papaefthymiou, Richard P. Blakemore Jan 1985

Mossbauer Spectroscopy Of Iron Biomineralization Products In Magnetotactic Bacteria, Richard B. Frankel, Georgia C. Papaefthymiou, Richard P. Blakemore

Physics

No abstract provided.

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Advances In Verification Technology, David W. Hafemeister Jan 1985

Advances In Verification Technology, David W. Hafemeister

Physics

The alleged limits of verification techniques have been used to justify lack of action at the negotiating table, but advances in computer science and optics should help dispel doubts about the verifiability of treaties

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Microaerobic Conditions Are Required For Magnetite Formation Within Aquaspirillum Magnetotacticum, R. P. Blakemore, K. A. Short, D. A. Bazylinski, Charles Rosenblatt, Richard B. Frankel Jan 1985

Microaerobic Conditions Are Required For Magnetite Formation Within Aquaspirillum Magnetotacticum, R. P. Blakemore, K. A. Short, D. A. Bazylinski, Charles Rosenblatt, Richard B. Frankel

Physics

The amount of magnetite (Fe3O4) within magnetosomes of the microaerophilic bacterium Aquaspirillum magnetotacticum varies with oxygen and nitrogen supply. The development of optical methods for directly measuring cell magnetism in culture samples has enabled us to quantitate bacterial Fe3O4 yields. We measured final cell yields, average cell magnetic moments, and magnetosome yields of growing cells. Cultures were grown with NO3-, NH4+, or both, in sealed, unshaken vials with initial headspace Po2 values ranging from 0 (trace) to 21 kPa.

More than 50% of cells had detectable …

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Motion Of A Plane Front During Crystallization, Alexander Umantsev Jan 1985

Motion Of A Plane Front During Crystallization, Alexander Umantsev

Chemistry and Physics Faculty Working Papers

Many authors have studied the growth rates of crystals with a plane front. It is known that, if the advance of the boundary is determined by deviation of its state from equilibrium, then various regimes can be realized in the system, depending on the external conditions. 1,2 However, they have not yet been obtained as different solutions of a single problem. In our work, the integral equation representing normal growth of a crystal is solved by means of an asymptotic expansion by the method of Laplace. In the second part we construct an algorithm for obtaining numerical solutions to the …

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