Showing papers by "Argonne National Laboratory published in 1988"
TL;DR: In this paper, the authors developed three indices of pattern derived from information theory and fractal geometry for 94 quadrangles covering most of the eastern United States using digitized maps.
Abstract: Landscape ecology deals with the patterning of ecosystems in space. Methods are needed to quantify aspects of spatial pattern that can be correlated with ecological processes. The present paper develops three indices of pattern derived from information theory and fractal geometry. Using digitized maps, the indices are calculated for 94 quadrangles covering most of the eastern United States. The indices are shown to be reasonably independent of each other and to capture major features of landscape pattern. One of the indices, the fractal dimension, is shown to be correlated with the degree of human manipulation of the landscape.
1,453 citations
TL;DR: Theoretical predictions of an "inverted region," where increasing the driving force of the reaction will decrease its rate, have begun to be experimentally confirmed and a predicted nonlinear dependence of ET rates on the polarity of the solvent has also been confirmed.
Abstract: Intramolecular long-distance electron transfer (EI) has been actively studied in recent years in order to test existing theories in a quantitative way and to provide the necessary constants for predicting ET rates from simple structural parameters. Theoretical predictions of an "inverted region," where increasing the driving force of the reaction will decrease its rate, have begun to be experimentally confirmed. A predicted nonlinear dependence of ET rates on the polarity of the solvent has also been confirmed. This work has implications for the design of efficient photochemical charge-separation devices. Other studies have been directed toward determining the distance dependence of ET reactions. Model studies on different series of compounds give similar distance dependences. When different stereochemical structures are compared, it becomes apparent that geometrical factors must be taken into account. Finally, the mechanism of coupling between donor and acceptor in weakly interacting systems has become of major importance. The theoretical and experimental evidence favors a model in which coupling is provided by the interaction with the orbitals of the intervening molecular fragments, although more experimental evidence is needed.
1,125 citations
TL;DR: This paper describes an extension to the set of Basic Linear Algebra Subprograms targeted at matrix-vector operations that should provide for efficient and portable implementations of algorithms for high-performance computers.
Abstract: This paper describes an extension to the set of Basic Linear Algebra Subprograms. The extensions are targeted at matrix-vector operations that should provide for efficient and portable implementations of algorithms for high-performance computers.
846 citations
TL;DR: The Argonne ${v}_{14}$ plus Urbana VII Hamiltonian produces a softening in the neutron matter equation of state localized around twice nuclear matter density which may indicate a neutral pion condensate.
Abstract: We report microscopic calculations of the equation of state for dense nuclear and neutron matter. The calculations are performed for five Hamiltonians: the Argonne ${v}_{14}$ and Urbana ${v}_{14}$ two-nucleon potentials, both alone and with the Urbana VII three-nucleon potential, and the density-dependent Urbana ${v}_{14}$ plus three-nucleon interaction model of Lagaris, Friedman, and Pandharipande. The beta-stable equation of state and neutron star structure are also calculated for three of the models. The models with the three-nucleon potential bracket the density-dependent model and are significantly stiffer than those with an unmodified two-nucleon potential only. The Argonne ${v}_{14}$ plus Urbana VII Hamiltonian produces a softening in the neutron matter equation of state localized around twice nuclear matter density which may indicate a neutral pion condensate.
767 citations
TL;DR: It is shown that poor meta-bolizers have negligible amounts of the cytochrome P450 enzyme P450dbl, providing a molecular explanation for one of man's most commonly defective genes.
Abstract: In population studies of individuals given the antihypertensive drug debrisoquine, two distinct phenotypes have been described: extensive metabolizers excrete 10-200 times more of the urinary metabolite 4-hydroxydebrisoquine than poor metabolizers. In family studies the poor-metabolizer phenotype behaves as an autosomal recessive trait with an incidence between 5% and 10% in the white population of Europe and North America, and extends to the deficient metabolism of more than 20 commonly prescribed drugs. Clinical studies have shown that such individuals are at high risk for the development of adverse side effects from these and probably many other drugs. Here we show that poor metabolizers have negligible amounts of the cytochrome P450 enzyme P450db1. We have cloned the human P450db1 complementary DNA and expressed it in mammalian cell culture. Furthermore, by directly cloning and sequencing cDNAs from several poor-metabolizer livers, we have identified three variant messenger RNAs that are products of mutant genes producing incorrectly spliced db1 pre-mRNA, providing a molecular explanation for one of man's most commonly defective genes (frequency of mutant alleles 35-43%).
701 citations
TL;DR: Neutron-diffraction measurements as a function of temperature show that the phase separation occurs reversibly near 320 K.
Abstract: Superconducting samples of ${\mathrm{La}}_{2}\mathrm{Cu}{\mathrm{O}}_{4+\ensuremath{\delta}}$ are shown by neutron powder diffraction to consist of two nearly identical orthorhombic phases. The primary phase has a stoichiometry near ${\mathrm{La}}_{2}$Cu${\mathrm{O}}_{4}$. The second phase is an oxygen-rich phase that is superconducting. The abundance of the second phase increases with the oxygen pressure at which the samples are annealed. Neutron-diffraction measurements as a function of temperature show that the phase separation occurs reversibly near 320 K.
462 citations
TL;DR: In this paper, nanophase compacts with average initial grain sizes of 12 nm were found to densify rapidly above 500 °C, with only a small increase in grain size.
Abstract: Ultrafine-grained, nanophase samples of TiO2 (rutile) were synthesized by the gas-condensation method and subsequent in situ compaction. The samples were studied by a number of techniques, including transmission electron microscopy, Vickers microharness measurements, and positron annihilation spectroscopy, as a function of sintering temperature. The nanophase compacts with average initial grain sizes of 12 nm were found to densify rapidly above 500 °C, with only a small increase in grain size. The hardness values obtained by this method are comparable to or greater than those for coarser-grained compacts, but are achieved at temperatures 400 to 600 °C lower than conventional sintering temperatures and without the need for sintering aids.
368 citations
TL;DR: The TRUEX (TRansUranium Extraction) process is a new generic actinide extraction/recovery process for the removal of all actinides from acidic nitrate and chloride nuclear waste solutions as discussed by the authors.
Abstract: The TRUEX (TRansUranium Extraction) process is a new generic actinide extraction/recovery process for the removal of all actinides from acidic nitrate and chloride nuclear waste solutions. A brief review of the relevant chemistry of the TRUEX process and a summary of the current status of development and deployment of TRUEX process flowsheets to treat specific acidic waste solutions at several U.S. DOE sites is presented.
319 citations
TL;DR: In this article, a wide variety of theories are discussed in detail: pure Yang-Mills, theories with massive or massless real matter fields, and theories with chiral matter, both for SU( N ) and for the case of a general compact gauge group.
304 citations
TL;DR: A new method for computing analytic energy gradients for MRSDCI wave functions is discussed, which avoids the “coupled perturbed MCSCF” solutions for each coordinate direction, and avoids the transformation of any derivative-integral quantities from the AO to the MO basis.
Abstract: The COLUMBUS program system is a collection of Fortran programs for performing general multireference single- and double-excitation configuration interaction (MRSDCI) wave function optimization based on the graphical unitary group approach. The program system also includes integral generation, SCF and MCSCF orbital optimization, integral transformation, and wave function analysis programs. The original program system was written in 1980 to 1981. Since that time, it has evolved into one of the most popular MRSDCI program systems used in the computational chemistry community. The discussion of this evolution will include the exploitation of efficient matrix-matrix and matrix-vector product computational kernels, the use of generally contracted symmetry-adapted orbital basis sets, general Hamiltonian diagonalization procedures, energy-based internal walk selection, flexible DRT specification, improved coupling-coefficient evaluation methods, coupled-pair functional and multireference CPF capabilities, and density matrix construction. The numerous versions of the program system that are maintained at different sites and on different computers are now in the process of being merged. The source code for this combined version will be made available to the computational chemistry community. The source code for a specific computer may be generated from the source code for another computer by a single pass through a simple filter utility that is included with the program system. The directly supported computers will initially include various models of VAX, Cray, FPS, IBM, CDC, and ETA machines with the addition of other machines shortly thereafter. The ongoing developments of the COLUMBUS system that are discussed include a new method for computing analytic energy gradients for MRSDCI wave functions. This effective-density-matrix based method avoids the “coupled perturbed MCSCF” solutions for each coordinate direction, avoids the transformation of any derivative-integral quantities from the AO to the MO basis, avoids the transformation of the coupling coefficients from the MO to the AO basis, allows a subset of the MCSCF doubly occupied orbitals to be frozen in the CI wave function, and allows the MRSDCI wave function to be generated from general reference CSFs that are not necessarily related to the MCSCF expansion CSFs.
299 citations
TL;DR: In this article, the authors show that anomalous CH4-rich gas escapes at low flow rate and ambient temperature from seeps in serpentinized ultramafic rock in the Zambales Ophiolite, Philippines.
01 Sep 1988-Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment
TL;DR: The Collider Detector at Fermilab (CDF) as mentioned in this paper is a 5000 t magnetic detector built to study 2 TeV p p collisions at the Fermielab Tevatron, which is based on charged particle tracking, magnetic momentum analysis and fine-grained calorimetry.
Abstract: The Collider Detector at Fermilab (CDF) is a 5000 t magnetic detector built to study 2 TeV p p collisions at the Fermilab Tevatron. Event analysis is based on charged particle tracking, magnetic momentum analysis and fine-grained calorimetry. The combined electromagnetic and hadron calorimetry has approximately uniform granularity in rapidity-azimuthal angle and extends down to 2° from the beam direction. Various tracking chambers cover the calorimeter acceptance and extend charged particle tracking down to 2 mrad from the beam direction. Charged particle momenta are analyzed in a 1.5 T solenoidal magnetic field, generated by a superconducting coil which is 3 m in diameter and 5 m in length. The central tracking chamber measures particle momenta with a resolution better then δpT/pT2 = 2 × 10−3 (GeV/c)−1 in the region 40°
TL;DR: In this paper, the Dexter mechanism was used for long distance intramolecular triplet energy transfer and the results showed that it exhibits features similar to nonadiabatic electron transfer because both reactions are governed by the same theory of radiationless transitions.
Abstract: Recent efforts in these laboratories have been directed toward understanding the factors governing long distance intramolecular electron transfer (ET). In the models chosen for study the electronic coupling between donor and acceptor is sufficiently weak to assure nonadiabatic reactions. It occurred to them that long distance triplet energy transfer by the Dexter mechanism (TT) of which there are several examples in the literature should exhibit features similar to nonadiabatic electron transfer because both reactions are governed by the same theory of radiationless transitions. They therefore have started a program aimed at finding quantitative similarities and differences in these two processes when studied on directly comparable systems. Also, with one exception, the absolute rates of intramolecular triplet energy transfer have never been measured directly in liquid solution. In this communication they report their first results and conclusions.
TL;DR: In this paper, a two-step synthesis technique was described, starting with a stoichiometric oxide composition, which yields single-phase samples suitable for transport measurements, and showed that superconductivity in Ba1−xKxBiO3−y occurs only in a cubic perovskite phase which is stable at ≲600°C and which forms only for x > 0.25.
Abstract: The recent discovery of superconductivity near 30 K in Ba1−xKxBiO3−y (x≈0.4)1,2 is remarkable for two reasons. It is the first copper-free oxide superconductor that has a transition temperature (Tc) above that for the best intermetallic superconductor; and the structure is reported to be cubic, which excludes a two-dimensional metal–oxygen sublattice analogous to the CuO2 planes believed to be responsible for superconductivity in the copper-oxide-based superconductors. Cava et al.1 described a synthesis technique which involved starting with a 100% excess of KO2. At least part of the excess potassium was found to be present in the final sample (in a form not detectable by X-ray diffraction), resulting in samples that were not suitable for resistivity measurements and making a precise determination of the potassium and oxygen content in the superconducting phase impossible. Here we describe a two-step synthesis technique starting with a stoichiometric oxide composition, which yields single-phase samples suitable for transport measurements. Neutron powder diffraction studies of samples with varying potassium concentration show that superconductivity in Ba1−xKxBiO3−y, occurs only in a cubic perovskite phase which is stable at ≲600°C and which forms only for x > 0.25. Within this cubic phase, Tc is highest for compositions near the structural phase transition (x ≈ 0.25) and decreases with increasing x.
TL;DR: The problem of strategy and hyperresolution some obstacles to the automation of reasoning, and the basic research problems: larry wos.
Abstract: automated reasoning 33 basic research problems dcnx automated reasoning 33 basic research problems automated reasoning 33 basic research problems automated reasoning 33 basic research problems automated reasoning 33 basic research problems ebook basic research problems citeseerx the problem of strategy and hyperresolution some obstacles to the automation of reasoning, and the basic research problems: larry wos a the problem of definition expansion and contraction springer the problem of choosing between logic programming and automated proofs in group theory with otter automated theorem finding by forward deduction based on interpersonal communication a goals based approach ebook research problems in discrete geometry the theory grid and grid theorists researchgate az murder goes artful papers of the conference gilak automated reasoning with otter beaconac getting started guide autocad 2015 ebook | browserfame physics solutions manual young hulot color life library of photography pixmax answer study guide intro to econometrics luger honda fit 2010 owners manual pwcgba gre quantitative practice test answers elosuk handbook of automated reasoning volume 1 ajkp thermochemistry problems number 2 answers knitson handbook of automated reasoning 2 volume set cvpi automated theorem finding by forward deduction based on profiting from the worlds economic crisis finding 0460 11 may june 2014 marking scheme durts check light on volvo vnl pdf kugauk sugar among the freaks wenyen solving quadratic equations by graphs and factoring answer key manually install flash ubuntu compax gator xuv 620i service manual mmmrsn sense of touch mifou cls 350 owner manual budgieuk tony duquette iwsun
TL;DR: The first experimental test of the physics of plasma wake-field acceleration performed at the Argonne National Laboratory Advanced Accelerator Test Facility is reported, and the results compared to theoretical predictions.
Abstract: We report the first experimental test of the physics of plasma wake-field acceleration performed at the Argonne National Laboratory Advanced Accelerator Test Facility. Megavolt-per-meter plasma wake fields are excited by a intense 21-MeV, multipiscosecond bunch of electrons in a plasma of density ${n}_{e}\ensuremath{\simeq}{10}^{13}$ ${\mathrm{cm}}^{\ensuremath{-}3}$, and probed by a low-intensity 15-MeV witness pulse with a variable delay time behind the intense bunch. Accelerating and deflecting wake-field measurements are presented, and the results compared to theoretical predictions.
TL;DR: Combined longitudinal and polar Kerr-effect measurements show that the anisotropy reverts to being in plane for films thicker than approx.
Abstract: The predicted perpendicular surface anisotropy is observed for ferromagnetic fcc Fe/Cu(100) via in situ polar Kerr-effect measurements. Square hysteresis loops are obtained for films 1.5 to 5.7 monolayers thick for 100-K growth. The region of stability of the perpendicularly magnetized state as a function of growth temperature and film thickness is delineated. Combined longitudinal and polar Kerr-effect measurements show that the anisotropy reverts to being in plane for films thicker than \ensuremath{\simeq}6 monolayers.
TL;DR: In this article, the authors make some comparisons between energy intensity decomposition and the formulation of economic indices and illustrate the useful properties of one particular index, the Divisia index, in performing energy-intensity decomposition.
TL;DR: This paper describes a model implementation and test software for the Level 2 Basic Linear Algebra Subprograms (Level 2 BLAS), targeted at matrix-vector operations with the aim of providing more efficient, but portable, implementations of algorithms on high-performance computers.
Abstract: This paper describes a model implementation and test software for the Level 2 Basic Linear Algebra Subprograms (Level 2 BLAS). Level 2 BLAS are targeted at matrix-vector operations with the aim of providing more efficient, but portable, implementations of algorithms on high-performance computers. The model implementation provides a portable set of FORTRAN 77 Level 2 BLAS for machines where specialized implementations do not exist or are not required. The test software aims to verify that specialized implementations meet the specification of Level 2 BLAS and that implementations are correctly installed.
TL;DR: In this paper, a characterization of algorithms that identify the optimal active constraints in a finite number of iterations is given, with a non-degeneracy assumption which is equivalent, in the standard nonlinear programming problem, to the assumption that there is a set of strictly complementary Lagrange multipliers.
Abstract: Nondegeneracy conditions that guarantee that the optimal active constraints are identified in a finite number of iterations are studied. Results of this type have only been established for a few algorithms, and then under restrictive hypothesis. The main result is a characterization of those algorithms that identify the optimal constraints in a finite number of iterations. This result is obtained with a nondegeneracy assumption which is equivalent, in the standard nonlinear programming problem, to the assumption that there is a set of strictly complementary Lagrange multipliers. As an important consequence of the authors’ results the way that this characterization applies to gradient projection and sequential quadratic programming algorithms is shown.
TL;DR: It is found that Co preferentially occupies the Cu(1) site, simultaneously attracting extra oxygen into these layers in an amount consistent with Co(III) replacing Cu(II), which reflects charge transfer among the ions.
Abstract: We present the results of a neutron powder-diffraction study on ${\mathrm{YBa}}_{2}$${\mathrm{Cu}}_{3\mathrm{\ensuremath{-}}\mathrm{x}}$${\mathrm{Co}}_{\mathrm{x}}$${\mathrm{O}}_{7\mathrm{\ensuremath{-}}\mathrm{y}}$. We find that Co preferentially occupies the Cu(1) site, simultaneously attracting extra oxygen into these layers in an amount consistent with Co(III) replacing Cu(II). This compound displays a transition from orthorhombic-to-tetragonal structure for x between 0.05 and 0.1, while ${T}_{c}$ decreases continuously and the compound becomes nonsuperconducting for x=0.4. We note several important relationships between bond-length changes, which reflect charge transfer among the ions. Also, we find that ${T}_{c}$ changes systematically with the Cu-O bond length.
TL;DR: Comparison of the human and rat db1 revealed 71 and 73% similarities of nucleotides and amino acids, respectively, which confirmed the common human defect in drug oxidation known as the "debrisoquine/sparteine polymorphism".
TL;DR: Mice inoculated intra peritoneally with EL-4 cells were cured of their ascites after intraperitoneal injection of 150 microcuries of the antigen-specific radioimmunoconjugate, suggesting a possible role for such conjugates in intracavitary cancer therapy.
Abstract: Alpha particles are energetic short-range ions whose higher linear energy transfer produces extreme cytotoxicity. An alpha-particle-emitting radioimmunoconjugate consisting of a bismuth-212-labeled monoclonal immunoglobulin M specific for the murine T cell/neuroectodermal surface antigen Thy 1.2 was prepared. Analysis in vitro showed that the radioimmunoconjugate was selectively cytotoxic to a Thy 1.2+ EL-4 murine tumor cell line. Approximately three bismuth-212-labeled immunoconjugates per target cell reduced the uptake of [3H]thymidine by the EL-4 target cells to background levels. Mice inoculated intraperitoneally with EL-4 cells were cured of their ascites after intraperitoneal injection of 150 microcuries of the antigen-specific radioimmunoconjugate, suggesting a possible role for such conjugates in intracavitary cancer therapy.
TL;DR: Comparison of the protein sequences deduced from the human and Chinese hamster cDNA clones indicates only eight amino acid differences, suggesting that IMP dehydrogenase is a highly conserved protein.
TL;DR: 3D Gaussian fluctuations in the specific heat of two single crystals imply that the number of order-parameter components is 7 +- 2, which is inconsistent with an O(2) Ginzburg-Landau theory.
Abstract: Gaussian fluctuations have been observed in the specific heat of two single crystals ${\mathrm{YBa}}_{2}$${\mathrm{Cu}}_{3}$${\mathrm{O}}_{7\mathrm{\ensuremath{-}}\mathrm{\ensuremath{\delta}}}$. Deviations from a BCS-type step are well accounted for by 3D Gaussian fluctuations whose amplitude ratio, in the cleaner sample, implies that the number of order-parameter components is 7\ifmmode\pm\else\textpm\fi{}2. This result is inconsistent with an O(2) Ginzburg-Landau theory.
TL;DR: It is suggested that the ``supermodulus effect'' observed for composition-modulated superlattices arises from the presence of the structurally disordered solid interfaces and not necessarily from electronic structure effects.
Abstract: It is suggested that the ``supermodulus effect'' observed for composition-modulated superlattices arises from the presence of the structurally disordered solid interfaces and not necessarily from electronic structure effects.
TL;DR: A strong correlation between ion mixing and the matrix properties, atomic mass, and cohesive energy, was observed and a correlation between ions and tracer impurity diffusion was also observed.
Abstract: A systematic study of ion-beam mixing of tracer impurities in thin metal films at low temperatures has been conducted. We have investigated the dependence of ion mixing on two matrix properties: atomic mass and cohesive energy. We have also studied the dependence of ion mixing on tracer impurity properties: its heat of mixing with the matrix and its thermal diffusivity in the matrix. The matrices investigated were thin films of C, Al, Ti, Fe, Ni, Cu, Mo, Ru, Ag, Hf, Ta, W, Pt, and Au. The tracer impurities, Al, Ti, Cr, Mn, Fe, Ni, Cu, Y, Nb, Mo, Ru, Ag, In, Sb, Hf, Ta, W, Pt, Au, and Bi, were deposited as ≤15 A layers near the midplanes of the specimens. All the tracer and matrix elements, except C, were deposited sequentially, without breaking vacuum. The samples were irradiated with 300–1000-keV Kr ions to doses 1015–1016 ions/cm2 at temperatures of 6 and/or 77 K. Most samples were analyzed at the irradiation temperature by He backscattering. A strong correlation between ion mixing and the matrix properties, atomic mass, and cohesive energy, was observed. A correlation between ion mixing and tracer impurity diffusion was also observed but not between ion mixing and the heat of mixing or relative mass of the impurity with the matrix. The results are interpreted within the framework of a thermal spike model of cascade diffusion.
TL;DR: In this paper, the authors studied the relationship between the oxygen isotope effect and the transition temperature of Ba0.625K 0.375BiO3 and found that this material has large isotope effects, indicating that the pairing mechanism is conventional.
Abstract: The nature of the superconducting pairing mechanism in the high-temperature superconducting oxides is still an open question. Shortly after the discovery of these materials, several groups began an intensive study of the oxygen isotope effect. For a monatomic conventional (BCS) superconductor, the transition temperature Tc is proportional to M–α, where M is the mass of the atom and α=0.5, assuming no anharmonicity for the phonon modes and no Coulomb interactions. For a multicomponent material, with an αi, defined for each ion with mass Mi. Thus, each element contributes to the overall α (which would still equal 0.5) with a weight dependent on the structure of the phonon modes that are important for superconductivity. Because the 16O/18O mass ratio is much smaller than the available mass ratios for the isotopes of the other atoms in these materials, the oxygen contribution to α (αox) should be the largest and thus in principle the easiest to measure. A zero or very small oxygen isotope effect would thus imply an unconventional pairing mechanism, although the suppression of in normal phonon-mediated superconductors is common. A large value of α (>0.3) indicates conventional (BCS) superconductivity. Ba1–xKxBiO3 was recently found to be superconducting1, with Tc ≈30 K. Unlike the planar cuprate supercon-dors, this material is cubic. Here we report on the 18O isotope effect for Ba0.625K0.375BiO3. We find that this material has a large isotope effect, indicating that the pairing mechanism is conventional (phonon-mediated).