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Articles 3961 - 3990 of 4106

Full-Text Articles in Physical Sciences and Mathematics

Equilibrium Properties Of Short Field-Reversed Configurations, Ross L. Spencer, M. Tuszewski Nov 1986

Equilibrium Properties Of Short Field-Reversed Configurations, Ross L. Spencer, M. Tuszewski

Faculty Publications

Some features of short field-reversed configuration (FRC) equilibria relevant to transport and stability are studied numerically and analytically. It is shown that magnetic field curvature effects significantly increase the FRC magnetization for plasma elongations epsilon is less than or equal to 4.

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Pinuxylon Woolardii Sp. Nov., A New Petrified Taxon Of Pinaceae From The Miocene Basalts Of Eastern Oregon, William D. Tidwell, Lee R. Parker, Vaughn K. Folkman Nov 1986

Pinuxylon Woolardii Sp. Nov., A New Petrified Taxon Of Pinaceae From The Miocene Basalts Of Eastern Oregon, William D. Tidwell, Lee R. Parker, Vaughn K. Folkman

Faculty Publications

Specimens of the new species Pinuxylon wollardii have been collected from Miocene strata near Kurkee, OR. These petrified specimens are unique in that, due to weathering, individual tracheids and ray cells can be separated for detailed SEM studies. This species is characterized by its high number of ray cells; numerous rays; large resin ducts which are commonly paired; primarily uniseriate pitting, two to five (usually three) small, oval or cirular pinoid pits per crossfield; and smooth walls on its transverse (ray) tracheids. The latter character relates this species to taxa in the subgenus Haploxylon of Pinus. Pinuxylon woolardii is most …

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Asymmetry In The Magnetoconductance Of Metal Wires And Loops, A. D. Benoit, S. Washburn, C. P. Umbach, R. B. Laibowitz, Richard A. Webb Oct 1986

Asymmetry In The Magnetoconductance Of Metal Wires And Loops, A. D. Benoit, S. Washburn, C. P. Umbach, R. B. Laibowitz, Richard A. Webb

Faculty Publications

Universal conductance fluctuations in wires and Aharonov-Bohm oscillations in loops are not symmetric about H=0. The observation of asymmetry in the periodic oscillations is possible when the phase-coherence length of the wave function is comparable to the separation of the voltage probes. In both cases, four-probe measurements yield resistances which depend on lead configuration. The asymmetries appear like Hall voltages, and are consistent with Onsager's relations.

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Sequence Alignment With Matched Sections, Jerrold R. Griggs, Philip J. Hanlon, Michael S. Waterman Oct 1986

Sequence Alignment With Matched Sections, Jerrold R. Griggs, Philip J. Hanlon, Michael S. Waterman

Faculty Publications

In molecular biology, two finite sequences are compared by displaying one sequence written over another in an alignment. The number of alignments of two sequences is related to the Stanton-Cowan numbers. This paper gives asymptotics for the number of alignments of two sequences of length n with matching sections of size at least b.

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Considerations Of Temperature Stability In A Cylindrical Plasma, S. Neil Rasband, Yao-Hui Xu Aug 1986

Considerations Of Temperature Stability In A Cylindrical Plasma, S. Neil Rasband, Yao-Hui Xu

Faculty Publications

A variational formulation is used to consider thermal equilibrium and stability for a cylindrical plasma modeled by dissipative magnetohydrodynamics. The parameter dependence of equilibrium solutions and their stability is followed using homotopy techniques. Solution branches and their connections are studied in relation to the applied fields.

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Observation Of Resonant Tunneling In Silicon Inversion Layers, A. B. Fowler, G. L. Timp, J. J. Wainer, Richard A. Webb Jul 1986

Observation Of Resonant Tunneling In Silicon Inversion Layers, A. B. Fowler, G. L. Timp, J. J. Wainer, Richard A. Webb

Faculty Publications

Measurements of the temperature and carrier-density dependence of the strongly localized conductance of short silicon inversion layers are reported. At the lowest temperatures we observe well-isolated, large conductance peaks whose width and temperature dependence are only consistent with resonant tunneling and are inconsistent with Mott hopping. Several new features are observed which we believe may be the result of Coulomb interactions.

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Identification Of Fibroblasts As A Major Site Of Albumin Catabolism In Peripheral Tissues, Jeffrey L. Strobel, Susan G. Cady, Thomas K. Borg, Louis Terracio, John W. Baynes, Suzanne R. Thorpe Jun 1986

Identification Of Fibroblasts As A Major Site Of Albumin Catabolism In Peripheral Tissues, Jeffrey L. Strobel, Susan G. Cady, Thomas K. Borg, Louis Terracio, John W. Baynes, Suzanne R. Thorpe

Faculty Publications

Rat serum albumin has been labeledw ith dilactitollZ5I- tyramine,( 12‘I-DLT) a radioactive tracer which remains entrappedw ithin lysosomes following cellular uptake and degradation of the carrier protein. Similar kinetics of clearance from the rat circulation were observed for albumin labeled conventionally with lZsI or 12‘I-DLT-albumin, both proteinhsa ving circulating half-lives of -2.2 days. In contrast, the recovery of whole body radioactivity had half-lives of -2.2 and 5.1 days, respectively, for the two protein preparations, indicating substantial retention of degradation products derived from catabolism of ”‘I-DLT-albumin. Measurement of total and acid-soluble radioactivity in tissues 2 or 4 days after injection of …

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Interaction Effects Among Two-Dimensional Electrons And Holes, S. Washburn, Richard A. Webb, E. E. Mendez, L. L. Chang, L. Esaki Jun 1986

Interaction Effects Among Two-Dimensional Electrons And Holes, S. Washburn, Richard A. Webb, E. E. Mendez, L. L. Chang, L. Esaki

Faculty Publications

We report large logarithmic corrections to the conductivity of two-dimensional electrons and holes in GaSb-InAs-GaSb double heterostructures. From ∼ 40 mK to 1 K, the conductivity increased with the logarithm of the temperature but with a slope as much as 30 times larger than estimated from the theories of weak localization and carrier interaction. The discrepancy apparently results from electron-hole interactions not included in the theory.

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Algebraic Geometry For Computer-Aided Geometric Design, Thomas W. Sederberg, Ronald N. Goldman Jun 1986

Algebraic Geometry For Computer-Aided Geometric Design, Thomas W. Sederberg, Ronald N. Goldman

Faculty Publications

Classical algebraic geometry has been virtually ignored in computer-aided geometric design. However, because it deals strictly with algorithms, it is really more suited to this field than is modern algebraic geometry, which introduces abstractions far removed from the algorithmic nature of computer-aided design. This tutorial examines resultants, curve implicitization, curve inversion, and curve intersection. Discussion follows a series of examples simple enough for those with only a modest algebra background to follow.

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Arnoldia Kuesii, A New Juvenile Fernlike Plant From The Lower Permian Of New Mexico, William D. Tidwell, Sidney Ash Jun 1986

Arnoldia Kuesii, A New Juvenile Fernlike Plant From The Lower Permian Of New Mexico, William D. Tidwell, Sidney Ash

Faculty Publications

A nearly complete juvenile fernlike plant is described here from Lower Permian rocks of New Mexico. The fossil consists of a horizontal rhizome with roots, a short thick upright aerial branch, and a tuft of dimorphic leaves. It is assigned to Arnodia kuesii gen. et sp. n. and appears to be the first juvenile fernlike plant known from the Upper Paleozoic. Abundant palynomorphs and other plant fossils associated with the fossil indicate that it is Early Permian in age.

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On The Atomic Decomposition Of H^1 And Interpolation, Robert Sharpley May 1986

On The Atomic Decomposition Of H^1 And Interpolation, Robert Sharpley

Faculty Publications

© 1986 by American Mathematical Society

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Identification Of N Epsilon-Carboxymethyllysine As A Degradation Product Of Fructoselysine In Glycated Protein, Mahtab U. Ahmed, Suzanne R. Thorpe, John W. Baynes Apr 1986

Identification Of N Epsilon-Carboxymethyllysine As A Degradation Product Of Fructoselysine In Glycated Protein, Mahtab U. Ahmed, Suzanne R. Thorpe, John W. Baynes

Faculty Publications

The chemistry of Maillard or browning reactionosf glycated proteins was studied using the model compound, Nu-formyl-W-fructoselysine(f FL), an analog of glycated lysine residues in protein. Incubation of fFL (15 mM) at physiological pH and temperature in 0.2 M phosphate buffer resulted in formation of lVcarboxymethyllysine (CML) in about 40% yield after 15 days. CML was formed by oxidative cleavage of fFL between C-2 and C-3 of the carbohydrate chain and erythronic acid (EA) was identified a s , the split product formed in the reaction. Neither CML nor EA was formed from fFL under a nitrogen atmosphere. The rate of …

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Nonexistence Of Stable Harmonic Maps To And From Certain Homogeneous Spaces And Submanifolds Of Euclidean-Space, Ralph Howard, S Walter Wei Mar 1986

Nonexistence Of Stable Harmonic Maps To And From Certain Homogeneous Spaces And Submanifolds Of Euclidean-Space, Ralph Howard, S Walter Wei

Faculty Publications

Call a compact Riemannian manifold M a strongly unstable manifold if it is not the range or domain of a nonconstant stable harmonic map and also the homotopy class of any map to or from M contains elements of arbitrarily small energy. If M is isometrically immersed in Euclidean space, then a condition on the second fundamental form of M is given which implies M is strongly unstable. As compact isotropy irreducible homogeneous spaces have "standard" immersions into Euclidean space this allows a complete list of the strongly unstable compact irreducible symmetric spaces to be made.

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Direct Observation Of Ensemble Averaging Of The Aharonov-Bohm Effect In Normal-Metal Loops, C. P. Umbach, C. Van Haesendonck, R. B. Laibowitz, S. Washburn, Richard A. Webb Jan 1986

Direct Observation Of Ensemble Averaging Of The Aharonov-Bohm Effect In Normal-Metal Loops, C. P. Umbach, C. Van Haesendonck, R. B. Laibowitz, S. Washburn, Richard A. Webb

Faculty Publications

Aharonov-Bohm magnetoconductance oscillations have been measured in series arrays of 1, 3, 10, and 30 submicron-diameter Ag loops. At constant temperature, the amplitude of the h/e oscillations is observed to decrease as the square root of number of loops, while the amplitude of h/2e conductance oscillations, measured in the same samples, is independent of the number of series loops. This is direct confirmation of the ensemble averaging properties of h/e oscillations in multiloop systems. The amplitude of the h/e oscillations is in good agreement with recent calculations.

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Nonequilibrium Fluctuations Studied By A Rarefied Gas Simulation, Alejandro Garcia Jan 1986

Nonequilibrium Fluctuations Studied By A Rarefied Gas Simulation, Alejandro Garcia

Faculty Publications

A dilute gas under a constant heat flux is studied with use of a Monte Carlo simulation based on the Boltzmann equation. Results for several spatial correlation functions of equal-time fluctuations are reported and compared qualitatively with previous fluctuating hydrodynamics calculations for liquids.

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Multivariate Rational Approximation, Ronald A. Devore, Xiang Ming Yu Jan 1986

Multivariate Rational Approximation, Ronald A. Devore, Xiang Ming Yu

Faculty Publications

No abstract provided.

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Interconnected Reproductive And Vegetative Remains Of Populus (Salicaceae) From The Middle Eocene Green River Formation, Northeastern Utah, William D. Tidwell, Steven R. Manchester, David L. Dilcher Jan 1986

Interconnected Reproductive And Vegetative Remains Of Populus (Salicaceae) From The Middle Eocene Green River Formation, Northeastern Utah, William D. Tidwell, Steven R. Manchester, David L. Dilcher

Faculty Publications

A new specimen from the Middle Eocene Evacuation Creek Member of the Green River Formation in northeastern Utah shows a twig with several leaves of Populus wilmattae Crockrell and a fruiting raceme attache. This specimen establishes for the first time the type of fruits borne by P. wilmattae and provides additional characters with which to assess its taxonomic and evolutionary status. An associated seed shows attached placental hairs like those of extant species of Populus. The Green River fossil differs from extant Populus species in having basically palmate leaf venation and in bearing its fruiting axis on a young twig. …

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Sequences In Power Residue Classes, Duncan A. Buell, Richard H. Hudson Jan 1986

Sequences In Power Residue Classes, Duncan A. Buell, Richard H. Hudson

Faculty Publications

Using A. Weil’s estimates the authors have given bounds for the largest prime P0 such that all primes P > P0 have sequences of quadratic residues of length m. For m ≤ 8 the smallest prime having m consecutive quadratic residues is ≡ 3(mod 4) and P0 ≡ 1 (mod 4). The reason for this phenomenon is investigated in this paper and the theory developed is used to successfully uncover analogous phenomena for rth power residues, r ≥ 2, r even.

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Reply To Comment On "Subduction Of The Caribbean Plate And Basement Uplifts In The Overriding South American Plate", James N. Kellogg, William E. Bonini Dec 1985

Reply To Comment On "Subduction Of The Caribbean Plate And Basement Uplifts In The Overriding South American Plate", James N. Kellogg, William E. Bonini

Faculty Publications

No abstract provided.

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Temperature Dependence Of The Normal-Metal Aharonov-Bohm Effect, S. Washburn, C. P. Umbach, R. B. Laibowitz, Richard A. Webb Oct 1985

Temperature Dependence Of The Normal-Metal Aharonov-Bohm Effect, S. Washburn, C. P. Umbach, R. B. Laibowitz, Richard A. Webb

Faculty Publications

The amplitude of h/e periodic oscillations in the magnetoresistance of very small normal-metal (Au) rings, as well as the harmonic h/2e, have been studied as a function of temperature. The amplitudes depend on the temperature T roughly as T-1/2, as expected from the averaging of conduction channels in the absence of inelastic scattering, but may not be entirely consistent with this model. At the lowest T, the size of the fluctuations in the conductance is about ΔG∼e2/h, as predicted recently.

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Glycation Of Amino Groups In Protein, Nancy G. Watkins, Suzanne R. Thorpe, John W. Baynes Sep 1985

Glycation Of Amino Groups In Protein, Nancy G. Watkins, Suzanne R. Thorpe, John W. Baynes

Faculty Publications

Ribonuclease A has been used as a model protein for studying the specificity of glycation of amino groups in protein under physiological conditions (phosphate buffer, pH 7.4, 37 “C). Incubation of RNase with glucose led to an enhanced rate of inactivation of the enzyme relative to the rate of modification of lysine residues, suggesting preferential modification of active site lysine residues. Sites of glycation of RNase were identified by amino acid analysis of tryptic peptides isolated by reverse-phase high pressure liquid chromatography and phenylboronate affinity chromatography. Schiff base adducts were trapped with Na- BH&N and the a-amino group of Lys-1 …

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Inequalities Relating Sectional Curvatures Of A Submanifold To The Size Of Its 2nd Fndamental Form And Applications To Pinching Theorems For Submanifolds, Ralph Howard, S Walter Wei Aug 1985

Inequalities Relating Sectional Curvatures Of A Submanifold To The Size Of Its 2nd Fndamental Form And Applications To Pinching Theorems For Submanifolds, Ralph Howard, S Walter Wei

Faculty Publications

No abstract provided.

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A Generalized Molien Function For Field Theoretical Hamiltonians, Jeffrey W. Felix, Dorian M. Hatch Jul 1985

A Generalized Molien Function For Field Theoretical Hamiltonians, Jeffrey W. Felix, Dorian M. Hatch

Faculty Publications

A generating function, or Molien function, the coefficients of which give the number of independent polynomial invariants in G, has been useful in the Landau and renormalization group theories of phase transitions. Here a generalized Molien function for a field theoretical Hamiltonian (with short-range interactions) of the most general form invariant in a group G is derived. This form is useful for more general renormalization group calculations. Its Taylor series is calculated to low order for the FGamma-2 representation of the space group R[3 bar]c and also for the l=1 (faithful) representation of SO(3).

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Observation Of H/E Aharonov-Bohm Oscillations In Normal-Metal Rings, Richard A. Webb, S. Washburn, C. P. Umbach, R. B. Laibowitz Jun 1985

Observation Of H/E Aharonov-Bohm Oscillations In Normal-Metal Rings, Richard A. Webb, S. Washburn, C. P. Umbach, R. B. Laibowitz

Faculty Publications

Magnetoresistance oscillations periodic with respect to the flux h/e have been observed in submicron-diameter Au rings, along with weaker h/2e oscillations. The h/e oscillations persist to very large magnetic fields. The background structure in the magnetoresistance was not symmetric about zero field. The temperature dependence of both the amplitude of the oscillations and the background are consistent with the recent theory by Stone.

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Effects Of Dissipation And Temperature On Macroscopic Quantum Tunneling, S. Washburn, Richard A. Webb, R. F. Voss, S. M. Faris Jun 1985

Effects Of Dissipation And Temperature On Macroscopic Quantum Tunneling, S. Washburn, Richard A. Webb, R. F. Voss, S. M. Faris

Faculty Publications

Measurements of the tunneling rate Γ out of the zero-voltage state for several Nb edge junctions with differing shunt capacitances are described. At zero temperature, increasing the shunt capacitance lowers Γ in agreement with dissipative calculations of the macroscopic-quantum-tunneling rate. As temperature increases, ln[Γ(T)/Γ(0)]∝T2 as recently predicted.

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Origin Of The Peaked Structure In The Conductance Of One-Dimensional Silicon Accumulation Layers, Richard A. Webb, A. Hartstein, J. J. Wainer, A. B. Fowler Apr 1985

Origin Of The Peaked Structure In The Conductance Of One-Dimensional Silicon Accumulation Layers, Richard A. Webb, A. Hartstein, J. J. Wainer, A. B. Fowler

Faculty Publications

We have made extensive studies of the temperature, gate voltage, and electric field dependences of the conductance peaks in small silicon inversion layers in order to distinguish between resonant-tunneling models and a hopping model. We find that many of the peaks are consistent only with a hopping model, whereas some could be consistent with an early resonant-tunneling model. None of our structure is consistent with resonant tunneling if the recent formulation of Stone and Lee is correct.

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Uses And Abuses Of Wastewater Injection Wells In Hawaii, F. L. Peterson, June Ann Oberdorfer Mar 1985

Uses And Abuses Of Wastewater Injection Wells In Hawaii, F. L. Peterson, June Ann Oberdorfer

Faculty Publications

During the past two decades in Hawaii, more than 500 injection wells for the disposal of domestic sewage wastewater have been constructed and operated. Thus far, contamination of potable groundwater supplies has not been a problem. Many of the injection wells, however, have not performed as designed, and aquifer clogging and reduced injection capacity have produced numerous well failures resulting in public health, legal, and financial problems. Factors most commonly responsible for the well problems have been unfavorable hydrogeology, underdesign of injection well capacity, poor effluent quality, and lack of injection well maintenance. Detailed study of clogging mechanisms in the …

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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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Flora Of The Lower Cretaceous Cedar Mountain Formation Of Utah And Colorado; Part Iii, Icacinoxylon Pittiense N. Sp., William D. Tidwell, Gregory F. Thayn, W. L. Stokes Feb 1985

Flora Of The Lower Cretaceous Cedar Mountain Formation Of Utah And Colorado; Part Iii, Icacinoxylon Pittiense N. Sp., William D. Tidwell, Gregory F. Thayn, W. L. Stokes

Faculty Publications

Icacinoxylon pittiense, a new species of angiospermous wood from the Lower Cretaceous Cedar Mountain Formation of Utah is described and compared with similar fossil and modern woods. It is distinguished from other species of Icacinoxylon by its thick-walled fiber-tracheids with their walls making up at least 50% of the total diameter of the cells, conspicuous bordered pits with obliquely crossing extended apertures on both the tangential and radial walls of its fiber-tracheids, scalariform perforation plates with as few as four or greater than 30 bars, transitional opposite to scalariform pitting on its vessel walls, thick-walled ray cells, and distinct sheath …

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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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