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Selected Works

1986

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Articles 31 - 60 of 62

Full-Text Articles in Physical Sciences and Mathematics

Thermal Decomposition Of Silane, Mark S. Gordon, David R. Gano, J. Stephen Binkley, Michael J. Frisch Apr 1986

Thermal Decomposition Of Silane, Mark S. Gordon, David R. Gano, J. Stephen Binkley, Michael J. Frisch

Mark S. Gordon

The essential features of the potential energy surface for the thermal decomposition of silane have been calculated with extended basis sets, augmented by correlation corrections. It is predicted that the transition state for the molecular elimination lies 56.9 kcaljmol above silane. For the reverse reaction, the transition state is less than 2 kcal/mol above the separated fragments, silylene and molecular hydrogen, but 4.8 kcal/mol above a long-range potential well. In the latter, the silylene-H2 separation is 1.78 A, and the bond in H2 has stretched by more than 0.05 A. This indicates a significant electronic interaction between the fragments even …

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Theoretical Studies Of Reactions Of Silanimine (H2sinh) And Its Isomer Aminosilylene (Hsinh2), Thanh N. Truong, Mark S. Gordon Apr 1986

Theoretical Studies Of Reactions Of Silanimine (H2sinh) And Its Isomer Aminosilylene (Hsinh2), Thanh N. Truong, Mark S. Gordon

Mark S. Gordon

The structure and reactivity of unsaturated singlet silicon-nitrogen compounds is theoretically investigated. Ab initio calculations demonstrate that the planar silylene HSiNH2 is the global minimum on the SiNH3 surface, with the planar doubly bound species H2SiNH 18 kcaljmol higher in energy. The internal rotational barriers are computed to be 26.9 kcaljmol for HSiNH2 and 37.9 kcaljmol for H2SiNH. However, the barrier for the inversion of H2SiNH is only 5.6 kcaljmol, so that inversion is favored over rotation for this species. The isomerization connecting H2SiNH to HSiNH2 has a barrier of 60 kcaljmol. The transition-state structures, as well as the exothermicities …

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Predatory Prokaryotes: Predation And Primary Consumption Evolved In Bacteria, Lynn Margulis, Ricardo Guerrero, Carlos Pedrós-Alió, Isabel Esteve, Jordi Mas, David Chase Apr 1986

Predatory Prokaryotes: Predation And Primary Consumption Evolved In Bacteria, Lynn Margulis, Ricardo Guerrero, Carlos Pedrós-Alió, Isabel Esteve, Jordi Mas, David Chase

Lynn Margulis (1938 - 2011)

Two kinds of predatory bacteria have been observed and characterized by light and electron microscopy in samples from freshwater sulfurous lakes in northeastern Spain. The first bacterium, named Vampirococcus, is Gram-negative and ovoidal (0.6 μm wide). An anaerobic epibiont, it adheres to the surface of phototrophic bacteria (Chromatium spp.) by specific attachment structures and, as it grows and divides by fission, destroys its prey. An important in situ predatory role can be inferred for Vampirococcus from direct counts in natural samples. The second bacterium, named Daptobacter, is a Gram-negative, facultatively anaerobic straight rod (0.5 × 1.5 μm) with a single …

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Improvement Of Trace Aluminum Determination By Electrothermal Atomic Absorption Spectrophotometry Using Phosphoric Acid, Chris Craney, Kurt Swartout, F. Smith, C. West Feb 1986

Improvement Of Trace Aluminum Determination By Electrothermal Atomic Absorption Spectrophotometry Using Phosphoric Acid, Chris Craney, Kurt Swartout, F. Smith, C. West

Chris L. Craney

No abstract provided.

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Northern Hemisphere Surface Air Temperature Variations: 1851-1984, P. D. Jones, S. C. B.Raper, Raymond S. Bradley, H. F. Diaz, P. M. Kelly, T. M. L.Wigley Feb 1986

Northern Hemisphere Surface Air Temperature Variations: 1851-1984, P. D. Jones, S. C. B.Raper, Raymond S. Bradley, H. F. Diaz, P. M. Kelly, T. M. L.Wigley

Raymond S Bradley

A new compilation of monthly mean surface air temperature for the Northern Hemisphere for 1851-1984 is presented based on land-based meteorological station data and fixed-position weather ship data. This compilation differs from others in two ways. First, a considerable amount of new data, previously hidden away in archives, has been included, thus improving both spatial and temporal coverage. Second, the station data have been analyzed to assess their homogeneity. Only reliable or corrected station data have been used in calculating area averages. Grid point temperature estimates have been made by interpolating onto a 50 latitude by 100 longitude grid for …

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Electrochemical Reduction Of Alkyl Halides At Vitreous Carbon Cathodes In Dimethylformamide, James Cleary, Mohammed Mubarak, Kenneth Viera, Mark Anderson, Dennis Peters Jan 1986

Electrochemical Reduction Of Alkyl Halides At Vitreous Carbon Cathodes In Dimethylformamide, James Cleary, Mohammed Mubarak, Kenneth Viera, Mark Anderson, Dennis Peters

Mark R. Anderson

At vitreous carbon electrodes in dimethylformamide which contains tetramethylammonium perchlorate, cyclic voltammograms for 1-iododecane, 1-bromodecane, and 2-bromooctane consist of one irreversible reduction wave signaling formation of the alkyl carbanion, whereas voltammograms for 2-iodooctane, t-butyl bromide, and t-butyl iodide reveal stepwise generation of the alkyl radical and carbanion. Large-scale electrolysis of 1-iododecane at reticulated vitreous carbon yields decane, eicosane, 1-decene, and 1-decanol; the first two compounds arise, respectively, from reaction of decyl carbanions with a proton donor and with unreduced alkyl iodide, whereas the last two species are produced via chemical attack of hydroxide ion on 1-iododecane. Reduction of 1-bromodecane results …

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Electrochemistry Of 1,1,4,4-Tetraphenyl-1,3-Butadiene, 1,1,4,4-Tetraphenyl-1,2-Butadiene, And 1,1,4,4-Tetraphenyl-1-Butene In Dimethylformamide, Tsu-Yu Chen, Mark Anderson, Dennis Peters Jan 1986

Electrochemistry Of 1,1,4,4-Tetraphenyl-1,3-Butadiene, 1,1,4,4-Tetraphenyl-1,2-Butadiene, And 1,1,4,4-Tetraphenyl-1-Butene In Dimethylformamide, Tsu-Yu Chen, Mark Anderson, Dennis Peters

Mark R. Anderson

In dimethylformamide containing tetra-n-butylammonium perchlorate, 1,1,4,4-tetraphenyl-1-butene exhibits a single polarographic wave; preparative-scale reduction of the starting material produces 1,1,4,4-tetraphenylbutane.A polarogram for 1,1,4,4-tetraphenyl-1,3-butadiene consists of three waves. Large-scale electrolysis of 1,1,4,4-tetraphenyl-1,3-butadiene at potentials corresponding to either the first or second wave yields 1,1,4,4-tetraphenyl-1-butene in the absence of a proton donor and a mixture of 1,1,4,4-tetraphenyl-2-butene and 1,1,4,4-tetraphenyl-1-butene in the presence of excess glacial acetic acid. If 1,1,4,4-tetraphenyl-1,3-butadiene is electrolyzed at a potential on the third polarographic wave, one obtains 1,1,4,4-tetraphenylbutane in the absence of a proton donor but a mixture of 1,1,4,4-tetraphenyl-2-butene and 1,1,4,4-tetraphenylbutane in the presence of glacial acetic acid. …

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On The Quadratic Form N12 +N22 +N32 - N42 In Z4, Andrei Ludu Jan 1986

On The Quadratic Form N12 +N22 +N32 - N42 In Z4, Andrei Ludu

Andrei Ludu

No abstract provided.

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Linear Perturbations Of A Constant Coefficient Differential Equation Subject To Mild Integral Smallness Conditions, William Trench Jan 1986

Linear Perturbations Of A Constant Coefficient Differential Equation Subject To Mild Integral Smallness Conditions, William Trench

William F. Trench

No abstract provided.

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Measurements Of Electron Energy Distribution In An Argon Positive Column, Chin Oi Hoong Jan 1986

Measurements Of Electron Energy Distribution In An Argon Positive Column, Chin Oi Hoong

Chin Oi Hoong

The argon positive column plasma of a cold cathode glow discharge is studied using a pulsed single Langmuir Probe technique. It is observed thatthe energy distribution of the electrons in the posotive column is non-maxwellian at a gas pressure of 0.5 mbar. An increase in the gas pressure seems to make the distribution more Maxwellian.

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Pennsylvania's Implementation Of The Surface Mining Control And Reclamation Act: An Assessment Of How "Cooperative Federalism" Can Make State Regulatory Programs More Effective, John C. Dernbach Jan 1986

Pennsylvania's Implementation Of The Surface Mining Control And Reclamation Act: An Assessment Of How "Cooperative Federalism" Can Make State Regulatory Programs More Effective, John C. Dernbach

John C. Dernbach

No abstract provided.

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Sem Views Of Oak Wood, Douglas D. Stokke Jan 1986

Sem Views Of Oak Wood, Douglas D. Stokke

Douglas D. Stokke

The anatomical structure of the secondary xylem (wood) of trees varies with location in the tree. The size, shape, and distribution of cell types varies not only between locations (i.e., stem vs. branch vs. root), but also within an annual ring or across annual rings at a given cross-sectional plane.

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Thermoluminescence (Tl) Dating In Seismic Hazard Evaluations: An Example From The Bonneville Basin, Utah, James P. Mccalpin Jan 1986

Thermoluminescence (Tl) Dating In Seismic Hazard Evaluations: An Example From The Bonneville Basin, Utah, James P. Mccalpin

James P. McCalpin

Thermoluminescence (TL) of minerals is the release of light when grains are heated to 1500 -5000 C. As sediments are buried longer they progressively acquire more TL from accumulated radiation damage from alpha, beta, and gamma rays and cosmic radiation. If the total amount of radiation dose received can be calculated, and the current dose rate measured, then dividing the total dose by the yearly dose rate will yield a TL age. Total doses are calculated by heating the sample until all TL is released, then re-irradiating the sample in the lab with known doses until the natural TL is …

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Π-Bond Strengths In Hp=Ph, H2p=P, Hp=Nh, And Hn=Nh, Michael W. Schmidt, Mark S. Gordon Jan 1986

Π-Bond Strengths In Hp=Ph, H2p=P, Hp=Nh, And Hn=Nh, Michael W. Schmidt, Mark S. Gordon

Mark S. Gordon

The chemistry of the HP=PH 1r bond found in the recently isolated diphosphene compounds is considered in several ways. The P=P 1r-bond strength is found by computing the rotation barrier (36 kcalfmol) and is compared to that found for HN=NH (63.5 kcalfmol) and HP=NH (47 kcalfmol). The structure of the HPPH anion is presented. Various electronic states of the H2PP isomer are considered and compared to those of HPPH. Dipole moments and PP stretching frequencies are reported. The concerted hydrogenation of diphosphene is also examined.

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The Prereversal Enhancement Of Thezonal Electric Field In The Equatorial Ionosphere, D. T. Farley, E. Bonelli, Bela G. Fejer, M. F. Larsen Jan 1986

The Prereversal Enhancement Of Thezonal Electric Field In The Equatorial Ionosphere, D. T. Farley, E. Bonelli, Bela G. Fejer, M. F. Larsen

Bela G. Fejer

The electric fields in the ionospheric E and F regions near the magnetic equator often show a strong eastward enhancement shortly after sunset and before the eastward (normally) daytime field reverses to westward. Several theoretical models of the low-latitude fields suggest that this enhancement is caused mainly or entirely by F region winds (the F region dynamo), but some authors have suggested that it could be produced solely by E region tidal winds. We give here additional calculations and arguments in support of the F region source. The enhancement of the eastward field for an eastward F region wind turns …

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Microbial Communities, Lynn Margulis, David Chase, Ricardo Guerrero Jan 1986

Microbial Communities, Lynn Margulis, David Chase, Ricardo Guerrero

Lynn Margulis (1938 - 2011)

No abstract provided.

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Renormalization-Group Analysis Of Heat Capacity Amplitude, Scott I. Chase, Miron Kaufman Jan 1986

Renormalization-Group Analysis Of Heat Capacity Amplitude, Scott I. Chase, Miron Kaufman

Miron Kaufman

Critical amplitudes A+ associated with the temperature variation of the heat capacity are analyzed by means of renormalization-group techniques in both position and momentum spaces. We describe a mechanism according to which the amplitudes A diverge as the critical exponent a approaches a nonpositive integer. In between two consecutive divergences at least one amplitude vanishes at least once. The coefficient P in the expansion A+ /A- =1—Pa+0 (a~) is computed by means of e expansion and Migdal-Kadanoff renormalization-group technique. Systems for which the critical exponent alpha is negative but larger than —1 exhibit either a cusped heat capacity if A+/A- …

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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

Alejandro Garcia

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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A Prescription For Computer System Excellence, Robert Yacobellis Dec 1985

A Prescription For Computer System Excellence, Robert Yacobellis

Robert H Yacobellis

No abstract provided.

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Engineering Product Quality - Current Practices And Future Trends, Robert Yacobellis Dec 1985

Engineering Product Quality - Current Practices And Future Trends, Robert Yacobellis

Robert H Yacobellis

No abstract provided.

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The Rigid Backbone: A New Geometry For Percolation., Anthony Day, R. Tremblay, A.-M. Tremblay Dec 1985

The Rigid Backbone: A New Geometry For Percolation., Anthony Day, R. Tremblay, A.-M. Tremblay

Anthony Roy Day

It is shown that the diluted two-dimensional central-force problem belongs to a new class of percolation problems. Geometric properties such as the fractal dimension of the backbone, the correlation-length exponent, and the connectivity are completely different from those of previously studied percolation problems. Explicit calculations of the backbone and the construction of an algorithm which identifies the infinite rigid cluster clearly demonstrate the absence of singly connected bonds, the overwhelming importance of loops, and the long-range nature of the rigidity.

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A Highly Enantioselective Hydrolysis Of -3,5-Diacetoxycyclopent-1-Ene, Donald Deardorff, A. Matthews, D. Mcmeekin, Chris Craney Dec 1985

A Highly Enantioselective Hydrolysis Of -3,5-Diacetoxycyclopent-1-Ene, Donald Deardorff, A. Matthews, D. Mcmeekin, Chris Craney

Chris L. Craney

Exposure of -3,5-diacetoxycyclopent-1-ene () to the hydrolase enzyme acetylcholinesterase (from electric eel) affords In 94% yield 3()-acetoxy-5()-hydroxycyclopent-1-ene () with an e.e. of 96% (greater than 99% e.e. after one recrystallization).

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Positive Experiences With Software Metrics, Robert Yacobellis Dec 1985

Positive Experiences With Software Metrics, Robert Yacobellis

Robert H Yacobellis

No abstract provided.

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Nuclease Activity Of 1,10-Phenanthroline-Copper Ion: Reaction With Cgcgaattcgcg And Its Complexes With Netropsin And Ecori, Thomas Goyne, Michio Kuwabara, Chun Yoon, Theodore Thederahn, David Sigman Dec 1985

Nuclease Activity Of 1,10-Phenanthroline-Copper Ion: Reaction With Cgcgaattcgcg And Its Complexes With Netropsin And Ecori, Thomas Goyne, Michio Kuwabara, Chun Yoon, Theodore Thederahn, David Sigman

Thomas Goyne

No abstract provided.

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Electromagnetic And Isopin Breaking Effects Decrease Epsilon'/Epsilon, Jf Donoghue, E Golowich, Br Holstein, J Trampetic Dec 1985

Electromagnetic And Isopin Breaking Effects Decrease Epsilon'/Epsilon, Jf Donoghue, E Golowich, Br Holstein, J Trampetic

Barry R Holstein

No abstract provided.

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Chiral Perturbation-Theory Corrections To Kl-]-Gamma-Gamma, Jf Donoghue, Br Holstein, Ycr Lin Dec 1985

Chiral Perturbation-Theory Corrections To Kl-]-Gamma-Gamma, Jf Donoghue, Br Holstein, Ycr Lin

Barry R Holstein

No abstract provided.

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A Design Methodology For Software Quality, Robert Yacobellis Dec 1985

A Design Methodology For Software Quality, Robert Yacobellis

Robert H Yacobellis

No abstract provided.

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Solution Of Systems With Toeplitz Matrices Generated By Rational Functions, William F. Trench Dec 1985

Solution Of Systems With Toeplitz Matrices Generated By Rational Functions, William F. Trench

William F. Trench

No abstract provided.

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Extensions Of A Theorem Of Wintner On Systems With Asymptotically Constant Solutions, William F. Trench Dec 1985

Extensions Of A Theorem Of Wintner On Systems With Asymptotically Constant Solutions, William F. Trench

William F. Trench

No abstract provided.

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Splay Rigidity In The Diluted Central Force Elastic Network, Anthony Roy Day, A.-M. S. Tremblay, R. R. Tremblay Dec 1985

Splay Rigidity In The Diluted Central Force Elastic Network, Anthony Roy Day, A.-M. S. Tremblay, R. R. Tremblay

Anthony Roy Day

A Comment on the Letter by Wang and Harris, Phys. Rev. Lett. 55, 2459 (1985).

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