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Sample records for heterogeneous mixed-valence system

  1. Inorganic electron transfer: sharpening a fuzzy border in mixed valency and extending mixed valency across supramolecular systems.

    PubMed

    Kubiak, Clifford P

    2013-05-20

    This article describes research from our laboratory on the chemistry and spectroscopic properties of inorganic mixed-valence complexes. After a brief review of the seminal work of Taube, Creutz, Day, Robin, Hush, and others in the 1960s and the confounding efforts to identify the borderline between class II and III mixed-valence systems in the 1990s and early 2000s, we describe our first experiments to observe and analyze the coalescence of ν(CO) band shapes in the 1D IR spectra of mixed-valence complexes of the type {[Ru3O(OAc)6(CO)(L)]2-BL}(-), where L = a pyridyl ligand and BL = pyrazine or 4,4'-bipyridine, to estimate rate constants of intramolecular electron transfer (ET). The strong involvement of the bridging ligands in mixed-valence complexes of this type was first identified in the appearance of totally symmetric vibrational modes of pyrazine bridging ligands in the IR because of strong vibronic coupling within a three-state metal cluster-bridge-metal cluster model. Application of the Brunschwig-Creutz-Sutin semiclassical three-state model of mixed valency accounts well for the appearance of two intervalence charge-transfer bands that are observed in the near-IR region of the electronic absorption spectra of these mixed-valence ions. The direct spectroscopic observation of "mixed-valence isomers", the two alternate charge distributions of a mixed-valence ion, are described. The equilibrium constants of mixed-valence isomers provide quantitative thermodynamic estimates of the electronic coupling, H(ab). The extent of delocalization in many of the mixed-valent bridged dimers of triruthenium clusters produces unusual behavior, especially rate constants for ET that are independent of normal solvent reorganization energies but do depend on solvent dynamical dipolar reorientation times. The strong dependence of rates on solvent dynamics is also found to produce a non-Arrhenius dependence of ET rate constants on temperature, faster rates in frozen solutions

  2. Localized Multi-Reference Approach for Mixed-Valence Systems

    NASA Astrophysics Data System (ADS)

    Helal, W.; Evangelisti, S.; Leininger, T.; Maynau, D.

    2008-09-01

    The electronic structure and some important intra-molecular charge transfer parameters were investigated at CAS-SCF, MRCI, CAS+S and multi-reference localization levels of theory for purely organic mixed-valence molecules. In particular, a spiro cation has been taken as a model system. The potential energy surfaces of the ground and the lower three excited electronic states have been computed within a two-state model, at CAS-SCF using TZP basis for the spiro cation, and an adiabatic double-well potential has been obtained for the ground electronic state. Our analysis of the geometry through the reaction coordinate indicate that the spiro cation is a valence trapped bistable system. The effect of non-dynamical correlation, using a localized orbital approach, was found to be crucial for a quantitative description of the electronic structure and some important electron transfer parameters of these organic mixed-valence systems.

  3. The Total Position Spread in mixed-valence compounds: A study on the H4+ model system.

    PubMed

    Bendazzoli, Gian Luigi; El Khatib, Muammar; Evangelisti, Stefano; Leininger, Thierry

    2014-04-15

    The behavior of the Total Position Spread (TPS) tensor, which is the second moment cumulant of the total position operator, is investigated in the case of a mixed-valence model system. The system consists of two H2 molecules placed at a distance D. If D is larger than about 4 bohr, the singly ionized system shows a mixed-valence character. It is shown that the magnitude of the TPS has a strong peak in the region of the avoided crossing. We believe that the TPS can be a powerful tool to characterize the behavior of the electrons in realistic mixed-valence compounds.

  4. X-ray photoelectron spectroscopy of copper(II), copper(I), and mixed valence systems.

    PubMed

    Rupp, H; Weser, U

    1976-01-01

    X-ray photoelectron spectroscopy using copper(II), copper(I) and the mixed valence Cu(II)/Cu(I) compounds was employed as a means of studying electron transfer reactions in copper proteins. The X-ray photoelectron spectra of copper(II) compounds display characteristic satellites of both variable size and resolution. Some of these satellites could be assigned to specific ligand interactions. Unlike electron paramagnetic resonance spectroscopy, the X-ray photoelectron spectroscopic measurements of copper(I) compounds allowed the unequivocal assignment of this oxidation state. No satellites at all could be detected in the Cu(I) spectra. Furthermore, established mixed valence Cu(II)/Cu(I) complexes including Cu2SO3-CuSO3-2H2O and Cu4Cl5 (ethylenediamine)2 proved essentially a mixture of distinct portions of Cu(I) and Cu(II). This indicates that both oxidation states of copper survive in such complexes. In contrast, all Cu X-ray photoelectron signals of the more tentatively described mixed valence complexes Na2Cu3S3 and the mineral covellite, CuI4CuII2(S2)2S2, could be attributed exclusively to Cu(I). In view of the known binding of copper with sulfur in many copper proteins, it was of utmost importance to study the copper-sulfur interactions. We have demonstrated the absence of Cu(II) in CuS. This indicates strong metal-induced polarization of sulfur resulting in electron transfer to copper to yield Cu(I). PMID:953045

  5. Kondo lattice mixed valence behavior in the Ce(SnxPb1 - x)3 system

    NASA Astrophysics Data System (ADS)

    Teter, J.; Freitag, R.; Maury*, A.; Crow, J. E.; Mihalisin, T.

    1982-11-01

    Measurements of the electrical resistivity versus x and temperature T, for 1.5≤T≤300 K for the fcc system Ce(SnxPb1-x)3 are reported. CeSn3 has been shown to be a strongly mixed valent system with an average occupation number of the Ce 4f level nf of ˜0.4 at low temperatures. The electrical resistivity for Ce(SnxPb1-x)3 is compared to that obtained for other Ce based mixed valent-trivalent systems and to the predictions of the Newns and Hewson theory. These comparisons suggest that Ce(SnxPb1-x)3 is mixed valent for x≳0.5 and the scaling of the resistivity supports the previous result that CeSn3 is strong mixed valent with nf≂0.4.

  6. Variable-rung design for a mixed-valence two-legged ladder system situated in a dimensional crossover region.

    PubMed

    Otsubo, Kazuya; Kobayashi, Atsushi; Sugimoto, Kunihisa; Fujiwara, Akihiko; Kitagawa, Hiroshi

    2014-01-21

    Ladder systems situated in a crossover from one dimensionality to two dimensionalities have been an attractive research target, because the physical properties, which are associated with dimensionality, are strongly dependent on the number of constituent legs. However, control of the intraladder configuration and electronic properties based on the substitution of structural components remain challenging tasks in materials science. On the other hand, structural design using coordination chemistry offers crucial advantages for architectural and electronic variations through substitutions of metal-organic building blocks. Here, we show the rational design and electronic properties of novel metal complex-based two-legged ladder compounds with several organic rung units: 4,4'-bipyridine, trans-1,4-diaminocyclohexane, and 4,4'-azopyridine. Single-crystal X-ray studies show that these two-legged ladder compounds are composed of halogen-bridged mixed-valence one-dimensional chains (MX chains) as their constituent legs. Depending on the molecular shape of the organic rung units, unique configurations of two-legged ladder lattices with periodic distortion of the legs are achieved. In addition, the electronic absorption spectra show that intervalence charge-transfer (IVCT) band gap of the two-legged ladder system increases with increasing degree of distortion of the leg. We have demonstrated for the first time that a two-legged ladder system shows a unique relationship between IVCT energy and the distortion parameter of the leg, as distinct from a single MX chain system. These systematic investigations, not only of configurations based on the rung variation but also of electronic states in metal-organic ladder system, provide the possibility for wide and rational tunings of physical and electronic properties of metal complex-based functional materials. PMID:24392762

  7. The effects of couplings to symmetric and antisymmetric modes and minor asymmetry on the spectral properties of mixed-valence and related charge-transfer systems

    NASA Astrophysics Data System (ADS)

    Reimers, J. R.; Hush, N. S.

    1996-08-01

    The most common methods used to describe the energy levels of charge-transfer systems (including mixed-valence systems) are the linear response approach of Rice and co-workers and the essentially equivalent PKS model described initially by Piepho, Krausz, and Schatz. While these methods were quite successful, in their original form they omitted the effects of overall symmetric vibrations. As a consequence, in particular they were not capable of adequately describing the electronic band width in the strong-coupling limit: Hush and later Ondrechen et al. demonstrated that symmetric modes are essential in this case, and modern versions of these models now include them. Here, we explore the relationship between symmetric and antisymmetric modes, concentrating on how this is modified by the presence of weak (e.g., environmentally or substitutionally induced) asymmetry. For the symmetric case, we show that when the electronic Hamiltonian operators are transformed from their usual localized diabatic representation into a delocalized diabatic representation, the effects of the symmetric and antisymmetric modes are interchanged. The primary effect of weak asymmetry is to mix the properties of the various modes, and possible consequences of this for the spectroscopy of bacterial photosynthetic reaction centre and substituted Creutz—Taube cations are discussed. We also consider the problem from an adiabatic Bom—Oppenheimer perspective and examine the regions in which this approach is appropriate.

  8. Mulliken-Hush analysis of a bis(triarylamine) mixed-valence system with a N...N distance of 28.7 A.

    PubMed

    Heckmann, Alexander; Amthor, Stephan; Lambert, Christoph

    2006-07-28

    An organic mixed valence compound with a spacer length of 25 unsaturated bonds separating two amine redox centres was synthesised and the electron transfer behaviour was investigated in the context of a Mulliken-Hush analysis in order to estimate the longest redox centre separation for which an intervalence charge transfer band can be observed.

  9. Optical properties of mixed-valence platinum halides

    NASA Astrophysics Data System (ADS)

    Albin, Michael; Patterson, Howard H.

    1980-08-01

    Temperature dependent absorption spectra are reported for PtX 2-4 -PtX 2-6 doped in Cs 2ZrX 6 (X = Cl, Br). Intense, broad bands have been assigned as mixed-valence (MV) transitions. Vibronic structure has been observed for the MV bromide system. Our results are discussed in terms of a model proposed by Hush.

  10. Mixed-valence compound-based biosensor.

    PubMed

    Lin, M S; Wu, Y C; Jan, B I

    1999-01-01

    A cobalt(II)hexacyanoferrate-based biosensor has been prepared simply by codeposition of an enzyme, together with the electrochemical formation of a cobalt (II)hexacyanoferrate compound electrochemically. The compound can be generated at a constant potential of -0.05 V (vs. Ag/AgCl). This compound possesses the catalytic property of reducing hydrogen peroxide to water at the operating potential of 0.0 V vs. Ag/AgCl. The mixed-valence compound-based biosensor possesses an unique interference-independent feature, which is important for biomedical application; this feature is attributed to the low overvoltage characteristic of cobalt (II)hexacyanoferrate. The electrochemical glucose biosensor responds to a series of glucose injections with linearity up to 5 mM (with correlation coefficient R = 0.9999) and the sensitivity of the linear portion is 733 nA/(cm2 x mM). The detection limit is 2 x 10(-6)M (S/N = 3). Both the potential-dependent electron transfer rate constant and the apparent Michaelis-Menten constant were studied in rotating disk experiments. The apparent Michaelis-Menten constant, Km' calculated from the slope of the "Lineweaver-Burke" type reciprocal plot is 28 mM. A fast-response characteristic is observed in the rotating disk experiment and the 95% response time is 14.5 sec. No response was observed from the addition of either 2 x 10(-4)M galactose, acetaminophen, ascorbic acid, uric acid, cysteine, tyrosine, dopamine, or 1,4-dihydroxyquinone in the absence and/or in the presence of 5 x 10(-4)M glucose. PMID:10099513

  11. Electric-field-driven electron-transfer in mixed-valence molecules.

    PubMed

    Blair, Enrique P; Corcelli, Steven A; Lent, Craig S

    2016-07-01

    Molecular quantum-dot cellular automata is a computing paradigm in which digital information is encoded by the charge configuration of a mixed-valence molecule. General-purpose computing can be achieved by arranging these compounds on a substrate and exploiting intermolecular Coulombic coupling. The operation of such a device relies on nonequilibrium electron transfer (ET), whereby the time-varying electric field of one molecule induces an ET event in a neighboring molecule. The magnitude of the electric fields can be quite large because of close spatial proximity, and the induced ET rate is a measure of the nonequilibrium response of the molecule. We calculate the electric-field-driven ET rate for a model mixed-valence compound. The mixed-valence molecule is regarded as a two-state electronic system coupled to a molecular vibrational mode, which is, in turn, coupled to a thermal environment. Both the electronic and vibrational degrees-of-freedom are treated quantum mechanically, and the dissipative vibrational-bath interaction is modeled with the Lindblad equation. This approach captures both tunneling and nonadiabatic dynamics. Relationships between microscopic molecular properties and the driven ET rate are explored for two time-dependent applied fields: an abruptly switched field and a linearly ramped field. In both cases, the driven ET rate is only weakly temperature dependent. When the model is applied using parameters appropriate to a specific mixed-valence molecule, diferrocenylacetylene, terahertz-range ET transfer rates are predicted. PMID:27394108

  12. Electric-field-driven electron-transfer in mixed-valence molecules

    NASA Astrophysics Data System (ADS)

    Blair, Enrique P.; Corcelli, Steven A.; Lent, Craig S.

    2016-07-01

    Molecular quantum-dot cellular automata is a computing paradigm in which digital information is encoded by the charge configuration of a mixed-valence molecule. General-purpose computing can be achieved by arranging these compounds on a substrate and exploiting intermolecular Coulombic coupling. The operation of such a device relies on nonequilibrium electron transfer (ET), whereby the time-varying electric field of one molecule induces an ET event in a neighboring molecule. The magnitude of the electric fields can be quite large because of close spatial proximity, and the induced ET rate is a measure of the nonequilibrium response of the molecule. We calculate the electric-field-driven ET rate for a model mixed-valence compound. The mixed-valence molecule is regarded as a two-state electronic system coupled to a molecular vibrational mode, which is, in turn, coupled to a thermal environment. Both the electronic and vibrational degrees-of-freedom are treated quantum mechanically, and the dissipative vibrational-bath interaction is modeled with the Lindblad equation. This approach captures both tunneling and nonadiabatic dynamics. Relationships between microscopic molecular properties and the driven ET rate are explored for two time-dependent applied fields: an abruptly switched field and a linearly ramped field. In both cases, the driven ET rate is only weakly temperature dependent. When the model is applied using parameters appropriate to a specific mixed-valence molecule, diferrocenylacetylene, terahertz-range ET transfer rates are predicted.

  13. High-nuclearity mixed-valence clusters and mixed-valence chains: general approach to the calculation of the energy levels and bulk magnetic properties.

    PubMed

    Clemente-Juan, J M; Borrás-Almenar, J J; Coronado, E; Palii, A V; Tsukerblat, B S

    2009-05-18

    A general approach to the problem of electron delocalization in the high-nuclearity mixed-valence (MV) clusters containing an arbitrary number of localized spins and itinerant electrons is developed. Along with the double exchange, we consider the isotropic magnetic exchange between the localized electrons as well as the Coulomb intercenter repulsion. As distinguished from the previous approaches dealing with the MV systems in which itinerant electrons are delocalized over all constituent metal sites, here, we consider a more common case of systems exhibiting partial delocalization and containing several delocalized domains. Taking full advantage of the powerful angular momentum technique, we were able to derive closed form analytical expressions for the matrix elements of the full Hamiltonian. These expressions provide an efficient tool for treating complex mixed-valence systems, because they contain only products of 6j-symbols (that appear while treating the delocalized parts) and 9j-symbols (exchange interactions in localized parts) and do not contain high-order recoupling coefficients and 3j-symbols that essentially constrained all previous theories of mixed valency. The approach developed here is accompanied by an efficient computational procedure that allows us to calculate the bulk thermodynamic properties (magnetic susceptibility, magnetization, and magnetic specific heat) of high-nuclearity MV clusters. Finally, this approach has been used to discuss the magnetic properties of the octanuclear MV cluster [Fe(8)(mu(4)-O)(4)(4-Cl-pz)(12)Cl(4)](-) and the diphthalocyanine chains [YPc(2)].CH(2)Cl(2) and [ScPc(2)].CH(2)Cl(2) composed of MV dimers interacting through the magnetic exchange and Coulomb repulsion.

  14. Organic mixed-valence compounds: a playground for electrons and holes.

    PubMed

    Heckmann, Alexander; Lambert, Christoph

    2012-01-01

    Mixed-valence (MV) compounds are excellent model systems for the investigation of basic electron-transfer (ET) or charge-transfer (CT) phenomena. These issues are important in complex biophysical processes such as photosynthesis as well as in artificial electronic devices that are based on organic conjugated materials. Organic MV compounds are effective hole-transporting materials in organic light emitting diodes (OLEDs), solar cells, and photochromic windows. However, the importance of organic mixed-valence chemistry should not be seen in terms of the direct applicability of these species but the wealth of knowledge about ET phenomena that has been gained through their study. The great variety of organic redox centers and spacer moieties that may be combined in MV systems as well as the ongoing refinement of ET theories and methods of investigation prompted enormous interest in organic MV compounds in the last decades and show the huge potential of this class of compounds. The goal of this Review is to give an overview of the last decade in organic mixed valence chemistry and to elucidate its impact on modern functional materials chemistry.

  15. Photoinduced mixed valency in zinc porphyrin dimer of triruthenium cluster dyads.

    PubMed

    Henderson, Jane; Kubiak, Clifford P

    2014-10-20

    The preparation, electrochemistry, and spectroscopic characterization of three new species, (ZnTPPpy)Ru3O(OAc)6(CO)-pz-Ru3O(OAc)6(CO)L, where ZnTPPpy = zinc(II) 5-(4-pyridyl)-10,15,20-triphenylporphyin, L = pyridyl ligand, and pz = pyrazine, are reported. These porphyrin-coordinated Ru3O–BL–Ru3O (BL = bridging ligand) dyads are capable of undergoing intramolecular electron transfer from the photoexcited Zn porphyrin to Ru3O donor–bridge–acceptor dimer systems. Seven reversible redox processes are observed in the cyclic voltammograms of the newly synthesized dyads, showing no significant electrochemical interaction between the redox active porphyrin and the pyrazine-bridged ruthenium dimer of Ru3O trimers. From the electrochemical behavior of the dyads, large comproportionation constants (Kc = 6.0 × 10(7) for L = dmap) were calculated from the reduction potentials of the Ru(III)Ru(III)Ru(II) clusters, indicating a stable mixed-valence state. Electronic absorption spectra of the singly reduced mixed-valence species show two intervalence charge transfer (IVCT) bands assigned within the Brunschwig–Creutz–Sutin semiclassical three-state model as metal-to-bridge and metal-to-metal in character. The progression from most to least delocalized mixed-valence dimer ions, as determined by the divergence of the IVCT bands and in agreement with electrochemical data, follows the order of L = 4-dimethylaminopyridine (dmap) > pyridine (py) > 4-cyanopyridine (cpy). These systems show dynamic coalescence of the infrared spectra in the ν(CO) region of the singly reduced state. This sets the time scale of electron exchange at <10 ps. The electron transfer from the S1 excited state of the coordinated porphyrin to the dimer is predicted to be thermodynamically favorable, with ΔGFET(0) ranging from −0.54 eV for L = dmap to −0.62 eV for L = cpy. Observation of IVCT band growth under continual photolysis (λexc = 568 nm) confirms a phototriggered intramolecular electron

  16. A hexanuclear mixed-valence oxovanadium(IV,V) complex as a highly efficient alkane oxidation catalyst.

    PubMed

    Sutradhar, Manas; Kirillova, Marina V; Guedes da Silva, M Fátima C; Martins, Luísa M D R S; Pombeiro, Armando J L

    2012-11-01

    The new hexanuclear mixed-valence vanadium complex [V(3)O(3)(OEt)(ashz)(2)(μ-OEt)](2) (1) with an N,O-donor ligand is reported. It acts as a highly efficient catalyst toward alkane oxidations by aqueous H(2)O(2). Remarkably, high turnover numbers up to 25000 with product yields of up to 27% (based on alkane) stand for one of the most active systems for such reactions.

  17. Hierarchical Heteroaggregation of Binary Metal-Organic Gels with Tunable Porosity and Mixed Valence Metal Sites for Removal of Dyes in Water

    PubMed Central

    Mahmood, Asif; Xia, Wei; Mahmood, Nasir; Wang, Qingfei; Zou, Ruqiang

    2015-01-01

    Hierarchical heteronuclear metal-organic gels (MOGs) based on iron (Fe) and aluminium (Al) metal-organic framework (MOF) backbones bridged by tri-carboxylate ligands have firstly been synthesized by simple solvothermal method. Monometallic MOGs based on Fe or Al give homogenous monoliths, which have been tuned by introduction of heterogeneity in the system (mismatched growth). The developed gels demonstrate that surface areas, pore volumes and pore sizes can be readily tuned by optimizing heterogeneity. The work also elaborates effect of heterogeneity on size of MOG particles which increase substantially with increasing heterogeneity as well as obtaining mixed valence sites in the gels. High surface areas (1861 m2/g) and pore volumes (9.737 cc/g) were obtained for heterogeneous gels (0.5Fe-0.5Al). The large uptakes of dye molecules (290 mg/g rhodamine B and 265 mg/g methyl orange) with fast sorption kinetics in both neutral and acidic mediums show good stability and accessibility of MOG channels (micro and meso-/macropores), further demonstrating their potential applications in catalysis and sorption of large molecules. PMID:26014755

  18. A Fermi liquid theory of mixed-valence systems

    NASA Astrophysics Data System (ADS)

    Lin, Zonghan; Tsung-han, Lin; Liu, Fu-sui

    1985-06-01

    The local non-interacting Fermi liquid theory of Newns and Hewson is extended to include the interaction by introducing a molecular field parameter. The zero-temperature susceptibility and linear coefficient of specific heat are calculated.

  19. Electron transfer pathways in mixed-valence paracyclophane-bridged bis-triarylamine radical cations.

    PubMed

    Kaupp, Martin; Gückel, Simon; Renz, Manuel; Klawohn, Sascha; Theilacker, Kolja; Parthey, Matthias; Lambert, Christoph

    2016-01-01

    A series of paracyclophane (PC) bridged mixed-valence (MV) bis-triarylamine radical cations with different ([2.2], [3.3], [4.4]) linkers, with and without additional ethynyl spacers, have been studied by quantum-chemical calculations (BLYP35-D3/TZVP/COSMO) of ground-state structures, thermal electron-transfer barriers, hyperfine couplings, and lowest-lying excited states. Such PC-bridged MV systems are important intra-molecular model systems for inter-molecular electron transfer (ET) via π-stacked aromatics, since they allow enforcement of a more or less well-defined geometrical arrangement. Closely comparable ET barriers and electronic couplings for all [2.2] and [3.3] bridges are found for these class-II MV systems, irrespective of the use of pseudo-para and pseudo-meta connections. While the latter observation contradicts notions of quantum interference for off-resonant conduction through molecular wires, it agrees with the less intricate nodal structures of the highest occupied molecular orbitals. The ET in such MV systems may be more closely connected with hole conduction in the resonant regime. Computations on model cations, in which the [2.2] linkers have been truncated, confirm predominant through-space π-π electronic coupling. Systems with [4.4] PC bridges exhibit far more structural flexibility and concomitantly weaker electronic interactions between the redox centers.

  20. The electronic properties of mixed valence hydrated europium chloride thin film.

    PubMed

    Silly, M G; Charra, F; Lux, F; Lemercier, G; Sirotti, F

    2015-07-28

    We investigate the electronic properties of a model mixed-valence hydrated chloride europium salt by means of high resolution photoemission spectroscopy (HRPES) and resonant photoemission spectroscopy (RESPES) at the Eu 3d → 4f and 4d → 4f transitions. From the HRPES spectra, we have determined that the two europium oxidation states are homogeneously distributed in the bulk and that the hydrated salt film is exempt from surface mixed valence transition. From the RESPES spectra, the well separated resonant contributions characteristic of divalent and trivalent europium species (4f(6) and 4f(7) final states, respectively) are accurately extracted and quantitatively determined from the resonant features measured at the two edges. The partial absorption yield spectra, obtained by integrating the photoemission intensity in the valence-band region, can be well reproduced by atomic multiplet calculation at the M(4,5) (3d-4f) absorption edge and by an asymmetric Fano-like shape profile at the N(4,5) (4d-4f) absorption edge. The ratio of Eu(2+) and Eu(3+) species measured at the two absorption edges matches with the composition of the mixed valence europium salt as determined chemically. We have demonstrated that the observed spectroscopic features of the mixed valence salt are attributed to the mixed-valence ground state rather than surface valence transition. HRPES and RESPES spectra provide reference spectra for the study of europium salts and their derivatives. PMID:26105214

  1. The electronic properties of mixed valence hydrated europium chloride thin film.

    PubMed

    Silly, M G; Charra, F; Lux, F; Lemercier, G; Sirotti, F

    2015-07-28

    We investigate the electronic properties of a model mixed-valence hydrated chloride europium salt by means of high resolution photoemission spectroscopy (HRPES) and resonant photoemission spectroscopy (RESPES) at the Eu 3d → 4f and 4d → 4f transitions. From the HRPES spectra, we have determined that the two europium oxidation states are homogeneously distributed in the bulk and that the hydrated salt film is exempt from surface mixed valence transition. From the RESPES spectra, the well separated resonant contributions characteristic of divalent and trivalent europium species (4f(6) and 4f(7) final states, respectively) are accurately extracted and quantitatively determined from the resonant features measured at the two edges. The partial absorption yield spectra, obtained by integrating the photoemission intensity in the valence-band region, can be well reproduced by atomic multiplet calculation at the M(4,5) (3d-4f) absorption edge and by an asymmetric Fano-like shape profile at the N(4,5) (4d-4f) absorption edge. The ratio of Eu(2+) and Eu(3+) species measured at the two absorption edges matches with the composition of the mixed valence europium salt as determined chemically. We have demonstrated that the observed spectroscopic features of the mixed valence salt are attributed to the mixed-valence ground state rather than surface valence transition. HRPES and RESPES spectra provide reference spectra for the study of europium salts and their derivatives.

  2. Mixed valence Creutz-Taube ion analogues incorporating thiacrowns: synthesis, structure, physical properties, and computational studies.

    PubMed

    Adams, Harry; Costa, Paulo J; Newell, Mike; Vickers, Steven J; Ward, Michael D; Félix, Vítor; Thomas, Jim A

    2008-12-15

    A series of nine new complexes incorporating [Ru(II)Cl([n]aneS(3))] (n = 12, 14, 16) metal centers bridged by three ditopic ligands containing two monodentate sites (pyrazine, 4,4'-bipyridine, and 3,6-bis(4-pyridyl)-1,2,4,5-tetrazine) have been synthesized and fully characterized. The solid-state structures of three of the complexes have been further characterized by X-ray crystallography studies. Intermetallic interactions within the new systems have been probed using electrochemistry and optical spectroscopy. Cyclic voltammetry reveals that the three pyrazine bridged systems display two separate Ru(III)/(II) redox couples. Using spectroelectrochemistry, we have investigated the optical properties of these mixed valence, Creutz-Taube ion analogues. An analysis of the intervalence charge transfer bands for the complexes revealed that, despite possessing the same donor sets, the electronic delocalization within these systems is modulated by the nature of the coordinated thiacrown. Computational modeling using density function theory offers further evidence of interaction between metal centers and provides insights into how these interactions are mediated. PMID:19012395

  3. Composition dependence of electronic, magnetic, transport and morphological properties of mixed valence manganite thin films

    DOE PAGES

    Singh, Surendra; Freeland, J. W.; Fitzsimmons, Michael R.; Jeen, H.; Biswas, A.

    2016-07-27

    Mixed-valence manganese oxides present striking properties like the colossal magnetoresistance, metal-insulator transition (MIT) that may result from coexistence of ferromagnetic, metallic and insulating phases. Percolation of such phase coexistence in the vicinity of MIT leads to first-order transition in these manganites. However the length scales over which the electronic and magnetic phases are separated across MIT which appears compelling for bulk systems has been elusive in (La1-yPry)1-xCaxMnO3 films. Here we show the in-plane length scale over which charge and magnetism are correlated in (La0.4Pr0.6)1-xCaxMnO3 films with x = 0.33 and 0.375, across the MIT temperature. We combine electrical transport (resistance)more » measurements, x-ray absorption spectroscopy (XAS), x-ray magnetic circular dichroism (XMCD), and specular/off-specular x-ray resonant magnetic scattering (XRMS) measurements as a function of temperature to elucidate relationships between electronic, magnetic and morphological structure of the thin films. Using off-specular XRMS we obtained the charge-charge and charge-magnetic correlation length of these LPCMO films across the MIT. We observed different charge-magnetic correlation length for two films which increases below the MIT. The different correlation length shown by two films may be responsible for different macroscopic (transport and magnetic) properties.« less

  4. Ba6Sn6Se13: a new mixed valence selenostannate with NLO property.

    PubMed

    Feng, Kai; Jiang, Xingxing; Kang, Lei; Yin, Wenlong; Hao, Wenyu; Lin, Zheshuai; Yao, Jiyong; Wu, Yicheng; Chen, Chuangtian

    2013-10-01

    A new ternary selenostannate Ba6Sn6Se13 has been synthesized by a high temperature solid-state method. The compound crystallizes in the non-centrosymmetric orthorhombic space group P2(1)2(1)2(1) and may be represented as Ba6Sn5(2+)Sn(4+)Se13 with mixed valence Sn atoms. Sn(4+) cations lie in a tetrahedral environment, while Sn(2+) cations are found in two kinds of coordination environments: the trigonal pyramid and quadrangular pyramid. SnSe(n) (n = 3, 4, 5) polyhedra are further connected to generate a three-dimensional framework with Ba(2+) residing in cavities. Ba6Sn6Se13 shows moderate nonlinear optical response and is the first reported NLO compound in the Ba-Sn-Se system. In addition, diffuse reflectance spectroscopy measurement indicates that the band gap of Ba6Sn6Se13 is 1.52(2) eV and thermal analysis suggests that the compound melts incongruently. The theoretically calculated SHG response and band gap are in good agreement with experimental results.

  5. Composition dependence of charge and magnetic length scales in mixed valence manganite thin films.

    PubMed

    Singh, Surendra; Freeland, J W; Fitzsimmons, M R; Jeen, H; Biswas, A

    2016-01-01

    Mixed-valence manganese oxides present striking properties like the colossal magnetoresistance, metal-insulator transition (MIT) that may result from coexistence of ferromagnetic, metallic and insulating phases. Percolation of such phase coexistence in the vicinity of MIT leads to first-order transition in these manganites. However the length scales over which the electronic and magnetic phases are separated across MIT which appears compelling for bulk systems has been elusive in (La1-yPry)1-xCaxMnO3 films. Here we show the in-plane length scale over which charge and magnetism are correlated in (La0.4Pr0.6)1-xCaxMnO3 films with x = 0.33 and 0.375, across the MIT temperature. We combine electrical transport (resistance) measurements, x-ray absorption spectroscopy (XAS), x-ray magnetic circular dichroism (XMCD), and specular/off-specular x-ray resonant magnetic scattering (XRMS) measurements as a function of temperature to elucidate relationships between electronic, magnetic and morphological structure of the thin films. Using off-specular XRMS we obtained the charge-charge and charge-magnetic correlation length of these LPCMO films across the MIT. We observed different charge-magnetic correlation length for two films which increases below the MIT. The different correlation length shown by two films may be responsible for different macroscopic (transport and magnetic) properties. PMID:27461993

  6. Composition dependence of charge and magnetic length scales in mixed valence manganite thin films

    NASA Astrophysics Data System (ADS)

    Singh, Surendra; Freeland, J. W.; Fitzsimmons, M. R.; Jeen, H.; Biswas, A.

    2016-07-01

    Mixed-valence manganese oxides present striking properties like the colossal magnetoresistance, metal-insulator transition (MIT) that may result from coexistence of ferromagnetic, metallic and insulating phases. Percolation of such phase coexistence in the vicinity of MIT leads to first-order transition in these manganites. However the length scales over which the electronic and magnetic phases are separated across MIT which appears compelling for bulk systems has been elusive in (La1‑yPry)1‑xCaxMnO3 films. Here we show the in-plane length scale over which charge and magnetism are correlated in (La0.4Pr0.6)1‑xCaxMnO3 films with x = 0.33 and 0.375, across the MIT temperature. We combine electrical transport (resistance) measurements, x-ray absorption spectroscopy (XAS), x-ray magnetic circular dichroism (XMCD), and specular/off-specular x-ray resonant magnetic scattering (XRMS) measurements as a function of temperature to elucidate relationships between electronic, magnetic and morphological structure of the thin films. Using off-specular XRMS we obtained the charge-charge and charge-magnetic correlation length of these LPCMO films across the MIT. We observed different charge-magnetic correlation length for two films which increases below the MIT. The different correlation length shown by two films may be responsible for different macroscopic (transport and magnetic) properties.

  7. Localization-Delocalization in Bridged Mixed-Valence Metal Clusters: Vibronic PKS Model Revisited.

    PubMed

    Palii, A; Tsukerblat, B; Clemente-Juan, J M; Aldoshin, S M

    2015-09-24

    Here we describe a new vibronic model of mixed valence (MV) dimer inspired by the conventional Piepho, Krausz, and Schatz (PKS) approach. We attempted to partially lift the main restriction of the PKS model dealing with the vibronically independent moieties of a MV molecule. The refined version of the PKS model in which the bridging ligands are included deals with the three main interactions: electron transfer (integral t0) related to the high-symmetric ligand configuration, on-site vibronic coupling (parameter υ) arising from the modulation of the crystal field on the metal sites by the breathing displacements of their nearest ligand surroundings, and intercenter vibronic coupling (parameter ζ) describing the dependence of the electron transfer on ligand positions in the course of their breathing movement. We apply the modified model to the analysis of the adiabatic potentials and electronic density distributions in the minima of their lower sheets for the cases of one-electron MV dimer with long and short bridges and for the two-electron MV dimer exhibiting a valence disproportionation effect. The inclusion of the intercenter interaction in addition to the conventional PKS coupling is shown to produce a strong effect on the degree of localization in MV dimers and, in particular, on the assignments to the Robin and Day classes and on the conditions of stabilization of valence disproportionated states in bielectron transfer systems. PMID:26305153

  8. Composition dependence of charge and magnetic length scales in mixed valence manganite thin films

    PubMed Central

    Singh, Surendra; Freeland, J. W.; Fitzsimmons, M. R.; Jeen, H.; Biswas, A.

    2016-01-01

    Mixed-valence manganese oxides present striking properties like the colossal magnetoresistance, metal-insulator transition (MIT) that may result from coexistence of ferromagnetic, metallic and insulating phases. Percolation of such phase coexistence in the vicinity of MIT leads to first-order transition in these manganites. However the length scales over which the electronic and magnetic phases are separated across MIT which appears compelling for bulk systems has been elusive in (La1−yPry)1−xCaxMnO3 films. Here we show the in-plane length scale over which charge and magnetism are correlated in (La0.4Pr0.6)1−xCaxMnO3 films with x = 0.33 and 0.375, across the MIT temperature. We combine electrical transport (resistance) measurements, x-ray absorption spectroscopy (XAS), x-ray magnetic circular dichroism (XMCD), and specular/off-specular x-ray resonant magnetic scattering (XRMS) measurements as a function of temperature to elucidate relationships between electronic, magnetic and morphological structure of the thin films. Using off-specular XRMS we obtained the charge-charge and charge-magnetic correlation length of these LPCMO films across the MIT. We observed different charge-magnetic correlation length for two films which increases below the MIT. The different correlation length shown by two films may be responsible for different macroscopic (transport and magnetic) properties. PMID:27461993

  9. Electron transfer within a reaction path model calibrated by constrained DFT calculations: application to mixed-valence organic compounds.

    PubMed

    Mangaud, E; de la Lande, A; Meier, C; Desouter-Lecomte, M

    2015-12-14

    The quantum dynamics of electron transfer in mixed-valence organic compounds is investigated using a reaction path model calibrated by constrained density functional theory (cDFT). Constrained DFT is used to define diabatic states relevant for describing the electron transfer, to obtain equilibrium structures for each of these states and to estimate the electronic coupling between them. The harmonic analysis at the diabatic minima yields normal modes forming the dissipative bath coupled to the electronic states. In order to decrease the system-bath coupling, an effective one dimensional vibronic Hamiltonian is constructed by partitioning the modes into a linear reaction path which connects both equilibrium positions and a set of secondary vibrational modes, coupled to this reaction coordinate. Using this vibronic model Hamiltonian, dissipative quantum dynamics is carried out using Redfield theory, based on a spectral density which is determined from the cDFT results. In a first benchmark case, the model is applied to a series of mixed-valence organic compounds formed by two 1,4-dimethoxy-3-methylphenylene fragments linked by an increasing number of phenylene bridges. This allows us to examine the coherent electron transfer in extreme situations leading to a ground adiabatic state with or without a barrier and therefore to the trapping of the charge or to an easy delocalization.

  10. Mixed-valence cytoplasmic iron granules are linked to anaerobic respiration.

    PubMed

    Glasauer, S; Langley, S; Boyanov, M; Lai, B; Kemner, K; Beveridge, T J

    2007-02-01

    Intracellular granules containing ferric and ferrous iron formed in Shewanella putrefaciens CN32 during dissimilatory reduction of solid-phase ferric iron. It is the first in situ detection at high resolution (150 nm) of a mixed-valence metal particle residing within a prokaryotic cell. The relationship of the internal particles to Fe(III) reduction may indicate a respiratory role.

  11. Electron hamiltonian renormalized by optical phonons in a two-orbital model of mixed valence

    NASA Astrophysics Data System (ADS)

    Spał, J.; Chao, K. A.

    1985-02-01

    We use a poor man's scaling argument along the line developed by Hewson in order to obtain an effective electronic model of mixed valence, with its interaction parameters renormalized by virtual optical phonon excitations. The atomic (f) electrons acquire a finite bandwidth, in addition to the renormalization of the hybridization.

  12. Dissipative electron transfer dynamics in mixed valence dimers: Microscopic approach to the solid state problem

    NASA Astrophysics Data System (ADS)

    Palii, Andrew; Bosch-Serrano, Cristian; Clemente-Juan, Juan Modesto; Coronado, Eugenio; Tsukerblat, Boris

    2013-07-01

    We propose a microscopic analytical approach to the description of the low-temperature dissipative intracluster electron transfer dynamics in centrosymmetric one-electron mixed-valence (MV) dimers. The dissipative system (bath) is supposed to consist of the acoustic phonons of the crystal surrounding that are coupled to the delocalized electron(s) of a MV dimer. Although the concept of the bath is the spin-boson model is more generic, the present consideration is relevant, for example, to a MV bi-center impurity in an ionic crystal. The model allows us to develop an approximate microscopic approach within which the relaxation processes are explicitly taken into account without additional assumption regarding spectral function of the bath. It is assumed that initially the extra electron is localized on a certain center and then the time-dependent localization probability (averaged value of the electron dipole moment) is evaluated with the emphasis on the damping of the amplitude of the Rabi oscillations. The approach assumes the following conditions: (i) the vibrational spectrum of the crystal does not show the presence of local modes; (ii) the itinerant electron is weakly coupled to the long-waves acoustic phonons which is peculiar to fully delocalized Robin and Day class III MV systems; (iii) the Debye energy ℏωD exceeds the electronic resonance energy gap 2β (β is the electron transfer parameter). We have demonstrated that the dissipation in this case is super-ohmic with the low-frequency spectral function J(ω) ∝ ω5. The time dependences of the localization probabilities show nearly picosecond damped oscillations. The longitudinal relaxation time T1 has been shown to be two times shorter than the decoherence time T2 thus giving the upper bound for T2, T2 ≤ 2T1.

  13. Electrical conductivity in two mixed-valence liquids.

    PubMed

    Yao, Wenzhi; Kelley, Steven P; Rogers, Robin D; Vaid, Thomas P

    2015-06-01

    Two different room-temperature liquid systems were investigated, both of which conduct a DC electrical current without decomposition or net chemical transformation. DC electrical conductivity is possible in both cases because of the presence of two different oxidation states of a redox-active species. One system is a 1 : 1 molar mixture of n-butylferrocene (BuFc) and its cation bis(trifluoromethane)sulfonimide salt, [BuFc(+)][NTf2(-)], while the other is a 1 : 1 molar mixture of TEMPO and its cation bis(trifluoromethane)sulfonimide salt, [TEMPO(+)][NTf2(-)]. The TEMPO-[TEMPO(+)][NTf2(-)] system is notable in that it is an electrically conducting liquid in which the conductivity originates from an organic molecule in two different oxidation states, with no metals present. Single-crystal X-ray diffraction of [TEMPO(+)][NTf2(-)] revealed a complex structure with structurally different cation-anion interactions for cis- and trans [NTf2(-)] conformers. The electron transfer self-exchange rate constant for BuFc/BuFc(+) in CD3CN was determined by (1)H NMR spectroscopy to be 5.4 × 10(6) M(-1) s(-1). The rate constant allowed calculation of an estimated electrical conductivity of 7.6 × 10(-5)Ω(-1) cm(-1) for BuFc-[BuFc(+)][NTf2(-)], twice the measured value of 3.8 × 10(-5)Ω(-1) cm(-1). Similarly, a previously reported self-exchange rate constant for TEMPO/TEMPO(+) in CH3CN led to an estimated conductivity of 1.3 × 10(-4)Ω(-1) cm(-1) for TEMPO-[TEMPO(+)][NTf2(-)], a factor of about 3 higher than the measured value of 4.3 × 10(-5)Ω(-1) cm(-1).

  14. Quantitative calculation of magnetic and electric properties in a d(2)–d(3) mixed-valence vanadium dimer complex.

    PubMed

    Suzuki, Hidenori; Satoko, Chikatoshi

    2014-01-29

    The electronic structure and magnetic properties in the mixed-valence d(2)-d(3) vanadium dimer complex ((PY5Me(2))(2)V(2)(μ-5, 6-dmbzim))(4+) under an electric field are investigated by using the density functional theory and the effective Hamiltonian method. With the aim of controlling the localization-delocalization of the excess electron, an electric field is applied in the direction along the two vanadium atoms. The ground state changes with an increase of the electric field from the highest spin S D 5=2 state to the intermediate spin S D 3=2 state, and then it changes to the lowest spin S D 1=2 state. Thus, in this realistic mixed-valence dimer system, the possibility of controlling the spin state by using the electric field is shown. Various magnetic and electric properties of this mixed-valence dimer complex are also calculated using our effective Hamiltonian. The methodology in this paper is quite general and is a useful approach for the calculation of electronic structures in various magnetic complexes.

  15. Epitaxial growth and electronic properties of mixed valence YbAl3 thin films

    NASA Astrophysics Data System (ADS)

    Chatterjee, Shouvik; Sung, Suk Hyun; Baek, David J.; Kourkoutis, Lena F.; Schlom, Darrell G.; Shen, Kyle M.

    2016-07-01

    We report the growth of thin films of the mixed valence compound YbAl3 on MgO using molecular-beam epitaxy. Employing an aluminum buffer layer, epitaxial (001) films can be grown with sub-nm surface roughness. Using x-ray diffraction, in situ low-energy electron diffraction, and aberration-corrected scanning transmission electron microscopy, we establish that the films are ordered in the bulk as well as at the surface. Our films show a coherence temperature of 37 K, comparable to that reported for bulk single crystals. Photoelectron spectroscopy reveals contributions from both f13 and f12 final states establishing that YbAl3 is a mixed valence compound and shows the presence of a Kondo Resonance peak near the Fermi-level.

  16. Solvent effect on intramolecular electron transfer rates of mixed-valence biferrocene monocation derivatives.

    PubMed

    Masuda, Y; Shimizu, C

    2006-06-01

    Intramolecular electron transfer (ET) rates in various solvents of mixed-valence biferrocene monocation (Fe(II), Fe(III)) and the 1',1' ''-diiodo and 1',1' ''-diethyl derivatives (respectively abbreviated as BFC(+), I(2)BFC(+), and Et(2)BFC(+)) were determined by means of the spin-lattice relaxation times of the protons, taking into account the local magnetic field fluctuation caused by the electron hopping between the two ferrocene units. We also determined the ET rates of a mixed-valence diferrocenylacetylene monocation (DFA(+)) in order to examine the effect of the insertion of an acetylene bridge between the two ferrocene units. The insertion of the bridge decreased the ET rate, while the effect of substitution on the cyclopentadienyl rings on the rate was minor. The observed rates for each mixed-valence monocation in various solvents did not correlate with the reorganization energies, but we did find a significant contribution of the solvent dynamics. The observed rates were considerably higher than those expected on the basis of the Sumi-Marcus-Nalder model in which the solvents were regarded as dielectric continua. The slope of the logarithm plot of the pre-exponential factors in various solvents for each mixed-valence monocation versus the inverse of the longitudinal dielectric relaxation times of the solvents was significantly smaller than unity, and the slope for DFA(+) was larger than those for BFC(+), I(2)BFC(+), and Et(2)BFC(+). These results were ascribed to a partial contribution of the dielectric friction to the dynamics along the solvent coordinate; the extent of the contribution decreased with a reduction in the ET distance. For the dynamics along the solvent coordinate of the ET reactions in methanol, the observed rates indicated an important contribution by the minor dielectric relaxation components with faster relaxation times, rather than the major component with an extraordinarily long relaxation time.

  17. Cluster molecular orbital description of the electronic structures of mixed-valence iron oxides and silicates

    USGS Publications Warehouse

    Sherman, David M.

    1986-01-01

    A molecular orbital description, based on spin-unrestricted X??-scattered wave calculations, is given for the electronic structures of mixed valence iron oxides and silicates. The cluster calculations show that electron hopping and optical intervalence charge-transger result from weak FeFe bonding across shared edges of FeO6 coordination polyhedra. In agreement with Zener's double exchange model, FeFe bonding is found to stabilize ferromagnetic coupling between Fe2+ and Fe3+ cations. ?? 1986.

  18. Di- and Trinuclear Mixed-Valence Copper Amidinate Complexes from Reduction of Iodine

    PubMed Central

    Lane, Andrew C.; Barnes, Charles L.; Antholine, William E.; Wang, Denan; Fiedler, Adam T.; Walensky, Justin R.

    2016-01-01

    Molecular examples of mixed-valence copper complexes through chemical oxidation are rare but invoked in the mechanism of substrate activation, especially oxygen, in copper-containing enzymes. To examine the cooperative chemistry between two metals in close proximity to each other we have begun to study the reactivity of a dinuclear Cu(I) amidinate complex. The reaction of [(2,6-Me2C6H3N)2C(H)]2Cu2, 1, with I2 in THF, CH3CN, and toluene affords three new mixed-valence copper complexes, [(2,6-Me2C6H3N)2C(H)]2Cu2(μ2-I3)(THF)2, 2, [(2,6-Me2C6H3N)2C(H)]2Cu2(μ2-I)(NCMe)2, 3, and [(2,6-Me2C6H3N)2C(H)]3Cu3(μ3-I)2, 4, respectively. The first two compounds have been characterized by UV-Vis and EPR spectroscopy and their molecular structure determined by X-ray crystallography. Both di- and trinuclear mixed-valence intermediates have been characterized for the reaction of compound 1 to compound 4 and the molecular structure of 4 has been determined by X-ray crystallography. The electronic structure of each of these complexes has also been investigated using density functional theory. PMID:26252561

  19. Connecting [NiFe]- and [FeFe]-hydrogenases: mixed-valence nickel-iron dithiolates with rotated structures.

    PubMed

    Schilter, David; Rauchfuss, Thomas B; Stein, Matthias

    2012-08-20

    New mixed-valence iron-nickel dithiolates are described that exhibit structures similar to those of mixed-valence diiron dithiolates. The interaction of tricarbonyl salt [(dppe)Ni(pdt)Fe(CO)(3)]BF(4) ([1]BF(4), where dppe = Ph(2)PCH(2)CH(2)PPh(2) and pdt(2-) = -SCH(2)CH(2)CH(2)S-) with P-donor ligands (L) afforded the substituted derivatives [(dppe)Ni(pdt)Fe(CO)(2)L]BF(4) incorporating L = PHCy(2) ([1a]BF(4)), PPh(NEt(2))(2) ([1b]BF(4)), P(NMe(2))(3) ([1c]BF(4)), P(i-Pr)(3) ([1d]BF(4)), and PCy(3) ([1e]BF(4)). The related precursor [(dcpe)Ni(pdt)Fe(CO)(3)]BF(4) ([2]BF(4), where dcpe = Cy(2)PCH(2)CH(2)PCy(2)) gave the more electron-rich family of compounds [(dcpe)Ni(pdt)Fe(CO)(2)L]BF(4) for L = PPh(2)(2-pyridyl) ([2a]BF(4)), PPh(3) ([2b]BF(4)), and PCy(3) ([2c]BF(4)). For bulky and strongly basic monophosphorus ligands, the salts feature distorted coordination geometries at iron: crystallographic analyses of [1e]BF(4) and [2c]BF(4) showed that they adopt "rotated" Fe(I) centers, in which PCy(3) occupies a basal site and one CO ligand partially bridges the Ni and Fe centers. Like the undistorted mixed-valence derivatives, members of the new class of complexes are described as Ni(II)Fe(I) (S = ½) systems according to electron paramagnetic resonance spectroscopy, although with attenuated (31)P hyperfine interactions. Density functional theory calculations using the BP86, B3LYP, and PBE0 exchange-correlation functionals agree with the structural and spectroscopic data, suggesting that the spin for [1e](+) is mostly localized in a Fe(I)-centered d(z(2)) orbital, orthogonal to the Fe-P bond. The PCy(3) complexes, rare examples of species featuring "rotated" Fe centers, both structurally and spectroscopically incorporate features from homobimetallic mixed-valence diiron dithiolates. Also, when the NiS(2)Fe core of the [NiFe]-hydrogenase active site is reproduced, the "hybrid models" incorporate key features of the two major classes of hydrogenase. Furthermore, cyclic

  20. Connecting [NiFe]- and [FeFe]-hydrogenases: mixed-valence nickel-iron dithiolates with rotated structures.

    PubMed

    Schilter, David; Rauchfuss, Thomas B; Stein, Matthias

    2012-08-20

    New mixed-valence iron-nickel dithiolates are described that exhibit structures similar to those of mixed-valence diiron dithiolates. The interaction of tricarbonyl salt [(dppe)Ni(pdt)Fe(CO)(3)]BF(4) ([1]BF(4), where dppe = Ph(2)PCH(2)CH(2)PPh(2) and pdt(2-) = -SCH(2)CH(2)CH(2)S-) with P-donor ligands (L) afforded the substituted derivatives [(dppe)Ni(pdt)Fe(CO)(2)L]BF(4) incorporating L = PHCy(2) ([1a]BF(4)), PPh(NEt(2))(2) ([1b]BF(4)), P(NMe(2))(3) ([1c]BF(4)), P(i-Pr)(3) ([1d]BF(4)), and PCy(3) ([1e]BF(4)). The related precursor [(dcpe)Ni(pdt)Fe(CO)(3)]BF(4) ([2]BF(4), where dcpe = Cy(2)PCH(2)CH(2)PCy(2)) gave the more electron-rich family of compounds [(dcpe)Ni(pdt)Fe(CO)(2)L]BF(4) for L = PPh(2)(2-pyridyl) ([2a]BF(4)), PPh(3) ([2b]BF(4)), and PCy(3) ([2c]BF(4)). For bulky and strongly basic monophosphorus ligands, the salts feature distorted coordination geometries at iron: crystallographic analyses of [1e]BF(4) and [2c]BF(4) showed that they adopt "rotated" Fe(I) centers, in which PCy(3) occupies a basal site and one CO ligand partially bridges the Ni and Fe centers. Like the undistorted mixed-valence derivatives, members of the new class of complexes are described as Ni(II)Fe(I) (S = ½) systems according to electron paramagnetic resonance spectroscopy, although with attenuated (31)P hyperfine interactions. Density functional theory calculations using the BP86, B3LYP, and PBE0 exchange-correlation functionals agree with the structural and spectroscopic data, suggesting that the spin for [1e](+) is mostly localized in a Fe(I)-centered d(z(2)) orbital, orthogonal to the Fe-P bond. The PCy(3) complexes, rare examples of species featuring "rotated" Fe centers, both structurally and spectroscopically incorporate features from homobimetallic mixed-valence diiron dithiolates. Also, when the NiS(2)Fe core of the [NiFe]-hydrogenase active site is reproduced, the "hybrid models" incorporate key features of the two major classes of hydrogenase. Furthermore, cyclic

  1. Neptunium (VI) and neptunium (VI/V) mixed valence cluster compounds

    SciTech Connect

    May, Iain

    2008-01-01

    {sup VI}O{sub 2}Cl{sub 2}(thf)]{sub n} offers the potential for more detailed exploration of neptunyl(VI) chemistry while the synthesis of the mixed valence cluster complex [{l_brace}Np{sup VI}O{sub 2}Cl{sub 2}{r_brace}{l_brace}Np{sup V}O{sub 2}Cl(thf){sub 3}{r_brace}{sub 2}] allows neptunyl(V) 'cation-cation' interactions to be proved in a molecular system.

  2. Stabilization of Th{sup 3+} ions into mixed-valence thorium fluoride

    SciTech Connect

    Dubois, Marc; Dieudonne, Belto; Mesbah, Adel; Bonnet, Pierre; El-Ghozzi, Malika; Renaudin, Guillaume; Avignant, Daniel

    2011-01-15

    The unusual oxidation state +3 of the thorium has been stabilized into a lithium containing non-stoichiometric mixed-valence (III/IV) thorium fluorinated phase with formula Li{sub 2+x}Th{sub 12}F{sub 50} (0mixed-valence III/IV thorium fluoride. The electrochemical insertion of Li{sup +} ions into the open channels of the host matrix has been carried out at 60 {sup o}C, using an alkylcarbonate PC-LiClO{sub 4} 1 M electrolyte. The Li{sup +} and Th{sup 3+} contents, both in the starting composition and the Li{sup +} inserted ones, were investigated by high resolution solid state {sup 7}Li NMR and EPR, respectively. -- Graphical abstract: Electrochemical insertion of Li{sup +} ions into mixed-valence III/IV thorium fluoride and EPR spectra for the raw and inserted compounds. Display Omitted

  3. Stabilization of Th 3+ ions into mixed-valence thorium fluoride

    NASA Astrophysics Data System (ADS)

    Dubois, Marc; Dieudonné, Belto; Mesbah, Adel; Bonnet, Pierre; El-Ghozzi, Malika; Renaudin, Guillaume; Avignant, Daniel

    2011-01-01

    The unusual oxidation state +3 of the thorium has been stabilized into a lithium containing non-stoichiometric mixed-valence (III/IV) thorium fluorinated phase with formula Li 2+ xTh 12F 50 (0< x<1.8). This phase is closely related to the Li 5.5Ce 12F 50 one, the structure of which has been determined from the combined single-crystal X-ray diffraction and high resolution synchrotron powder diffraction. In these phases, the Li + ions can be divided into two groups and are located either in locked positions or in open channels of the three dimensional framework. The amount of Li + ions in open channels can be variable, so that the afore mentioned single phase may be considered as an insertion compound. The Li + insertion is accompanied by the simultaneous reduction of a part of the Th 4+ ions, resulting in a mixed-valence III/IV thorium fluoride. The electrochemical insertion of Li + ions into the open channels of the host matrix has been carried out at 60 °C, using an alkylcarbonate PC-LiClO 4 1 M electrolyte. The Li + and Th 3+ contents, both in the starting composition and the Li + inserted ones, were investigated by high resolution solid state 7Li NMR and EPR, respectively.

  4. The electronic structure and optical properties of organic mixed valence anion radicals

    SciTech Connect

    Liberko, C.A.

    1992-01-01

    The electronic structure of planar and helical organic mixed valence anion radicals was studied. Cyanoimine derivatives of planar diquinones were synthesized and studied by electrochemical methods. Their anion radicals were generated electrochemically and found to be stable in air. These species had electronic absorptions in the near infrared region. The Visible and near infrared spectra as well as IR vibrational data are consistent with delocalized anion radicals. The molecular orbital energy level coefficients obtained from PPP semi-empirical molecular orbital calculations on neutral quinones, imides and cyanoimine derivatives of quinones, were used to correlate experimental data of their anion radicals. The calculation correlated the long wavelength absorptions of the anion radicals confirming that the absorptions arise from electronic transitions in delocalized species. The calculation was also valuable for assigning ESR hyperfine splittings. Including minor geometric perturbations in the calculation provides a method of predicting localization in mixed valence ion radicals. Helicene diquinones were studied by cyclic voltammetry. Their anion radicals, generated electrochemically, were studied by visible, near infrared, and ESR spectroscopies. The anion radicals were found to have electronic absorptions in the near infrared region tailing into the infrared. PPP calculations were consistent with the experimental data only if transannular interaction between the ends of the helix was included. The calculations and experimental observations are consistent with an electronic structure in which the anion radical is not only delocalized around the helix but also between the ends of the helix bonding them together in a Mobius fashion.

  5. Multipartite entanglement in heterogeneous systems

    NASA Astrophysics Data System (ADS)

    Goyeneche, Dardo; Bielawski, Jakub; Życzkowski, Karol

    2016-07-01

    Heterogeneous bipartite quantum pure states, composed of two subsystems with a different number of levels, cannot have both reductions maximally mixed. In this work, we demonstrate the existence of a wide range of highly entangled states of heterogeneous multipartite systems consisting of N >2 parties such that every reduction to one and two parties is maximally mixed. Two constructions of generating genuinely multipartite maximally entangled states of heterogeneous systems for an arbitrary number of subsystems are presented. Such states are related to quantum error correction codes over mixed alphabets and mixed orthogonal arrays. Additionally, we show the advantages of considering heterogeneous systems in practical implementations of multipartite steering.

  6. Can the second order multireference perturbation theory be considered a reliable tool to study mixed-valence compounds?

    PubMed

    Pastore, Mariachiara; Helal, Wissam; Evangelisti, Stefano; Leininger, Thierry; Malrieu, Jean-Paul; Maynau, Daniel; Angeli, Celestino; Cimiraglia, Renzo

    2008-05-01

    In this paper, the problem of the calculation of the electronic structure of mixed-valence compounds is addressed in the frame of multireference perturbation theory (MRPT). Using a simple mixed-valence compound (the 5,5(') (4H,4H('))-spirobi[ciclopenta[c]pyrrole] 2,2('),6,6(') tetrahydro cation), and the n-electron valence state perturbation theory (NEVPT2) and CASPT2 approaches, it is shown that the ground state (GS) energy curve presents an unphysical "well" for nuclear coordinates close to the symmetric case, where a maximum is expected. For NEVPT, the correct shape of the energy curve is retrieved by applying the MPRT at the (computationally expensive) third order. This behavior is rationalized using a simple model (the ionized GS of two weakly interacting identical systems, each neutral system being described by two electrons in two orbitals), showing that the unphysical well is due to the canonical orbital energies which at the symmetric (delocalized) conformation lead to a sudden modification of the denominators in the perturbation expansion. In this model, the bias introduced in the second order correction to the energy is almost entirely removed going to the third order. With the results of the model in mind, one can predict that all MRPT methods in which the zero order Hamiltonian is based on canonical orbital energies are prone to present unreasonable energy profiles close to the symmetric situation. However, the model allows a strategy to be devised which can give a correct behavior even at the second order, by simply averaging the orbital energies of the two charge-localized electronic states. Such a strategy is adopted in a NEVPT2 scheme obtaining a good agreement with the third order results based on the canonical orbital energies. The answer to the question reported in the title (is this theoretical approach a reliable tool for a correct description of these systems?) is therefore positive, but care must be exercised, either in defining the orbital

  7. Non-Ergodic Electron Transfer in Mixed-Valence Charge-Transfer Complexes.

    PubMed

    Matyushov, Dmitry V

    2012-06-21

    Theories of activated transitions traditionally separate the dynamics and statistics of the thermal bath in the reaction rate into the preexponential frequency factor for the dynamics and a Boltzmann factor for the statistics. When the reaction rate is comparable to relaxation frequencies of the medium, the statistics loses ergodicity and the activation barrier becomes dependent on the medium dynamics. This scenario is realized for mixed-valence self-exchange electron transfer at temperatures near the point of solvent crystallization. These complexes, studied by Kubiak and coworkers, display anti-Arrhenius temperature dependence on lowering temperature when approaching crystallization; that is, the reaction rate increases nonlinearly in Arrhenius coordinates. Accordingly, the solvent relaxation slows down following a power temperature law. With this functional form for the relaxation time, nonergodic reaction kinetics accounts well for the observations.

  8. Neutral-Type One-Dimensional Mixed-Valence Halogen-Bridged Platinum Chain Complexes with Large Charge-Transfer Band Gaps.

    PubMed

    Otake, Ken-ichi; Otsubo, Kazuya; Sugimoto, Kunihisa; Fujiwara, Akihiko; Kitagawa, Hiroshi

    2016-03-01

    One-dimensional (1D) electronic systems have attracted significant attention for a long time because of their various physical properties. Among 1D electronic systems, 1D halogen-bridged mixed-valence transition-metal complexes (the so-called MX chains) have been thoroughly studied owing to designable structures and electronic states. Here, we report the syntheses, structures, and electronic properties of three kinds of novel neutral MX-chain complexes. The crystal structures consist of 1D chains of Pt-X repeating units with (1R,2R)-(-)-diaminocychlohexane and CN(-) in-plane ligands. Because of the absence of a counteranion, the neutral MX chains have short interchain distances, so that strong interchain electronic interaction is expected. Resonance Raman spectra and diffuse-reflectance UV-vis spectra indicate that their electronic states are mixed-valence states (charge-density-wave state: Pt(2+)···X-Pt(4+)-X···Pt(2+)···X-Pt(4+)-X···). In addition, the relationship between the intervalence charge-transfer (IVCT) band gap and the degree of distortion of the 1D chain shows that the neutral MX chains have a larger IVCT band gap than that of cationic MX-chain complexes. These results provide new insight into the physical and electronic properties of 1D chain compounds. PMID:26901774

  9. Soft-x-ray resonant-photoemission study of mixed-valence TmSe

    NASA Astrophysics Data System (ADS)

    Oh, S.-J.; Allen, J. W.; Lindau, I.

    1984-08-01

    A single crystal of mixed-valence TmSe was studied by a resonant-photoemission technique with use of synchrotron radiation in the soft-x-ray region (hν=70-200 eV). The two Tm 4f emissions, one corresponding to the divalent Tm ion (4f13-->4f12) and the other to the trivalent Tm ion (4f12-->4f11), are both resonantly enhanced at photon energies close to the Tm 4d binding energy (170 to 180 eV), but their resonance behaviors differ from each other in that the former structure follows the multiplet structure of the 4d94f14 intermediate-state configuration whereas the latter shows multiplets of the 4d94f13 configuration. This can serve as a direct spectroscopic identification of the 4f occupation number of each component of the 4f emissions. Because the correlation energies between Tm 4d and 4f electrons and those between two 4f electrons are similar, these resonance thresholds come at about the same energy for both configurations. The bulk-sensitive constant-final-state (CFS) spectra show a superposition of both resonance features, confirming bulk mixed valency of TmSe. The bulk valence deduced from this CFS measurement is 2.62+/-0.15. The Tm 5p core-level emissions show two sets of spin-orbit peaks corresponding to two different Tm valences, and they also resonate in the same way as 4f emissions. The apparent spin-orbit splittings between 5p12 and 5p32 peaks differ by 1.4 eV for two Tm valences, most probably because of the exchange interaction between the 5p hole and 4f electrons. The variation of the relative intensity of the divalent peak to the trivalent peak as a function of photon energy clearly supports the existence of divalent surface layer(s), as recently reported. The electron escape depth has been calculated from this intensity ratio, and the results are compared with various theoretical models.

  10. Role of the electron transfer and magnetic exchange interactions in the magnetic properties of mixed-valence polyoxovanadate complexes.

    PubMed

    Calzado, Carmen J; Clemente-Juan, Juan M; Coronado, Eugenio; Gaita-Arino, Alejandro; Suaud, Nicolas

    2008-07-01

    Modeling the properties of high-nuclearity, high-electron-population, mixed-valence (MV) magnetic systems remains one of the open challenges in molecular magnetism. In this work, we analyze the magnetic properties of a series of polyoxovananadate clusters of formula [V 18O 42] (12-) and [V 18O 42] (4-). The first compound is a fully localized spin cluster that contains 18 unpaired electrons located at the metal sites, while the second one is a MV cluster with 10 unpaired electrons largely delocalized over the 18 metal sites. A theoretical model that takes into account the interplay between electron transfer and magnetic exchange interactions is developed to explain the unexpected enhancement of the antiferromagnetic coupling when the number of unpaired electrons is reduced from 18 to 10 in these clusters. In the MV area, these systems represent the most complex magnetic clusters studied theoretically so far. Because of the high complexity of the systems, the number of relevant parameters is too large for a conventional model Hamiltonian approach. We therefore perform a theoretical study that combines ab initio calculations with the model Hamiltonian. In this way, we use ab initio calculations performed on small fragments of the cluster to lower the degrees of freedom of the parameter set of the model Hamiltonian that operates in the whole MV cluster. This approach shows the usefulness of combining ab initio calculations with model Hamiltonians in order to explore the magnetic properties of large and complex molecular systems, emphasizing the key role played by the electron transfer in these model magnetic materials.

  11. Synthesis and thermolytic behavior of mixed-valence homo- and heterometallic group 14 alkoxides

    SciTech Connect

    Teff, D.J.; Minear, C.D.; Baxter, D.V.; Caulton, K.G.

    1998-05-18

    The mixed-valence molecule Sn{sup II}Sn{sup IV} (OPr){sub 6} is conveniently synthesized and is shown to exchange bridging and terminal alkoxides in solution in its Sn({micro}-OPr){sub 3}Sn(OPr){sub 3} structure. Pb{sub 3}SnO(POr){sub 8} is synthesized and shown to undergo an intramolecular fluxional process in solution. Both molecules are sufficiently volatile for CVD study, and comparison of CVD behaviors of these and of M(OPr){sub 2} (M = Sn, Pb), Sn(POr){sub 4}, SnZr(OPr){sub 6}, and Pb{sub 3}-ZrO(OPr){sub 8} shows the reducing capacity of the isopropoxide moiety dominates the thermolytic behavior of all these species, giving metallic Sn or Pb in all cases. Only Zr, when it is present, forms ZrO{sub 2}. The oxide in Pb{sub 3}SnO(POr){sub 8}yields PbO (and 2 Pb{sup 0} and 1 Sn{sup 0}), in contrast to the relative electropositivity of Sn and Pb, a fact attributed to kinetic control of CVD behavior.

  12. A mixed-valence complex of cobalt based on 3-methoxysalicylaldoxime.

    PubMed

    Yao, Tiantian; Lu, Jing; Li, Dacheng; Dou, Jianmin

    2014-04-01

    A new tetranuclear mixed-valence cobalt complex, namely di-μ2-azido-diazidodiethanolbis{μ2-2-[(hydroxyimino)methyl]-6-methoxyphenolato}bis{μ3-6-methoxy-2-[(oxidoimino)methyl]phenolato}dicobalt(II)dicobalt(III) ethanol disolvate, [Co(II)2Co(III)2(C8H7NO3)2(C8H8NO3)2(N3)4(C2H5OH)2]·2C2H5OH, has been synthesized by the reaction of Co(OAc)2·4H2O (OAc is acetate) with 3-methoxysalicylaldoxime (H2mosao) in an ethanol solution. In the complex, the four Co cations all display distorted octahedral coordination environments and they are bridged by two κ(2),κ(1),κ(1);μ3-mosao(2-) ligands, two κ(2),κ(2);μ2-Hmosao(-) ligands and two μ2-N3(-) anions to form a tetranuclear [Co4N4O4] cluster. Adjacent clusters are connected through weak C-H···N and C-H···O interactions, resulting in a two-dimensional supramolecular network parallel to the ac plane. The magnetic properties of the complex have also been studied.

  13. Investigating vibrational anharmonic couplings in cyanide-bridged transition metal mixed valence complexes using two-dimensional infrared spectroscopy

    NASA Astrophysics Data System (ADS)

    Slenkamp, Karla M.; Lynch, Michael S.; Van Kuiken, Benjamin E.; Brookes, Jennifer F.; Bannan, Caitlin C.; Daifuku, Stephanie L.; Khalil, Munira

    2014-02-01

    Using polarization-selective two-dimensional infrared (2D IR) spectroscopy, we measure anharmonic couplings and angles between the transition dipole moments of the four cyanide stretching (νCN) vibrations found in [(NH3)5RuIIINCFeII(CN)5]- (FeRu) dissolved in D2O and formamide and [(NC)5FeIICNPtIV(NH3)4NCFeII(CN)5]4- (FePtFe) dissolved in D2O. These cyanide-bridged transition metal complexes serve as model systems for studying the role of high frequency vibrational modes in ultrafast photoinduced charge transfer reactions. Here, we focus on the spectroscopy of the νCN modes in the electronic ground state. The FTIR spectra of the νCN modes of the bimetallic and trimetallic systems are strikingly different in terms of frequencies, amplitudes, and lineshapes. The experimental 2D IR spectra of FeRu and FePtFe and their fits reveal a set of weakly coupled anharmonic νCN modes. The vibrational mode anharmonicities of the individual νCN modes range from 14 to 28 cm-1. The mixed-mode anharmonicities range from 2 to 14 cm-1. In general, the bridging νCN mode is most weakly coupled to the radial νCN mode, which involves the terminal CN ligands. Measurement of the relative transition dipole moments of the four νCN modes reveal that the FeRu molecule is almost linear in solution when dissolved in formamide, but it assumes a bent geometry when dissolved in D2O. The νCN modes are modelled as bilinearly coupled anharmonic oscillators with an average coupling constant of 6 cm-1. This study elucidates the role of the solvent in modulating the molecular geometry and the anharmonic vibrational couplings between the νCN modes in cyanide-bridged transition metal mixed valence complexes.

  14. [Al2O4](-), a Benchmark Gas-Phase Class II Mixed-Valence Radical Anion for the Evaluation of Quantum-Chemical Methods.

    PubMed

    Kaupp, Martin; Karton, Amir; Bischoff, Florian A

    2016-08-01

    The radical anion [Al2O4](-) has been identified as a rare example of a small gas-phase mixed-valence system with partially localized, weakly coupled class II character in the Robin/Day classification. It exhibits a low-lying C2v minimum with one terminal oxyl radical ligand and a high-lying D2h minimum at about 70 kJ/mol relative energy with predominantly bridge-localized-hole character. Two identical C2v minima and the D2h minimum are connected by two C2v-symmetrical transition states, which are only ca. 6-10 kJ/mol above the D2h local minimum. The small size of the system and the absence of environmental effects has for the first time enabled the computation of accurate ab initio benchmark energies, at the CCSDT(Q)/CBS level using W3-F12 theory, for a class-II mixed-valence system. These energies have been used to evaluate wave function-based methods [CCSD(T), CCSD, SCS-MP2, MP2, UHF] and density functionals ranging from semilocal (e.g., BLYP, PBE, M06L, M11L, N12) via global hybrids (B3LYP, PBE0, BLYP35, BMK, M06, M062X, M06HF, PW6B95) and range-separated hybrids (CAM-B3LYP, ωB97, ωB97X-D, LC-BLYP, LC-ωPBE, M11, N12SX), the B2PLYP double hybrid, and some local hybrid functionals. Global hybrids with about 35-43% exact-exchange (EXX) admixture (e.g., BLYP35, BMK), several range hybrids (CAM-B3LYP, ωB97X-D, ω-B97), and a local hybrid provide good to excellent agreement with benchmark energetics. In contrast, too low EXX admixture leads to an incorrect delocalized class III picture, while too large EXX overlocalizes and gives too large energy differences. These results provide support for previous method choices for mixed-valence systems in solution and for the treatment of oxyl defect sites in alumosilicates and SiO2. Vibrational gas-phase spectra at various computational levels have been compared directly to experiment and to CCSD(T)/aug-cc-pV(T+d)Z data. PMID:27434425

  15. Lithium Storage in Microstructures of Amorphous Mixed-Valence Vanadium Oxide as Anode Materials.

    PubMed

    Zhao, Di; Zheng, Lirong; Xiao, Ying; Wang, Xia; Cao, Minhua

    2015-07-01

    Constructing three-dimensional (3 D) nanostructures with excellent structural stability is an important approach for realizing high-rate capability and a high capacity of the electrode materials in lithium-ion batteries (LIBs). Herein, we report the synthesis of hydrangea-like amorphous mixed-valence VOx microspheres (a-VOx MSs) through a facile solvothermal method followed by controlled calcination. The resultant hydrangea-like a-VOx MSs are composed of intercrossed nanosheets and, thus, construct a 3 D network structure. Upon evaluation as an anode material for LIBs, the a-VOx MSs show excellent lithium-storage performance in terms of high capacity, good rate capability, and long-term stability upon extended cycling. Specifically, they exhibit very stable cycling behavior with a highly reversible capacity of 1050 mA h g(-1) at a rate of 0.1 A g(-1) after 140 cycles. They also show excellent rate capability, with a capacity of 390 mA h g(-1) at a rate as high as 10 A g(-1) . Detailed investigations on the morphological and structural changes of the a-VOx MSs upon cycling demonstrated that the a-VOx MSs went through modification of the local VO coordinations accompanied with the formation of a higher oxidation state of V, but still with an amorphous state throughout the whole discharge/charge process. Moreover, the a-VOx MSs can buffer huge volumetric changes during the insertion/extraction process, and at the same time they remain intact even after 200 cycles of the charge/discharge process. Thus, these microspheres may be a promising anode material for LIBs.

  16. Electrically switchable magnetic molecules: inducing a magnetic coupling by means of an external electric field in a mixed-valence polyoxovanadate cluster.

    PubMed

    Cardona-Serra, Salvador; Clemente-Juan, Juan M; Coronado, Eugenio; Gaita-Ariño, Alejandro; Suaud, Nicolas; Svoboda, Ondrej; Bastardis, Roland; Guihéry, Nathalie; Palacios, Juan J

    2015-01-01

    Herein we evaluate the influence of an electric field on the coupling of two delocalized electrons in the mixed-valence polyoxometalate (POM) [GeV14 O40 ](8-) (in short V14 ) by using both a t-J model Hamiltonian and DFT calculations. In absence of an electric field the compound is paramagnetic, because the two electrons are localized on different parts of the POM. When an electric field is applied, an abrupt change of the magnetic coupling between the two delocalized electrons can be induced. Indeed, the field forces the two electrons to localize on nearest-neighbors metal centers, leading to a very strong antiferromagnetic coupling. Both theoretical approaches have led to similar results, emphasizing that the sharp spin transition induced by the electric field in the V14 system is a robust phenomenon, intramolecular in nature, and barely influenced by small changes on the external structure.

  17. Synthesis and spectral characterization of trinuclear, oxo-centered, carboxylate-bridged, mixed-valence iron complexes with Schiff bases.

    PubMed

    Singh, Atresh Kumar; Singh, Alok Kumar

    2012-10-01

    Some novel trinuclear, oxo-centered, carboxylate-bridged, mixed-valence iron complexes of the general formula [Fe(3)O(OOCR)(3)(SB)(3)L(3)] (where R=C(13)H(27), C(15)H(31) or C(17)H(35,) HSB=Schiff bases and L=Ethanol) have been synthesized by the stepwise substitutions of acetate ions from μ(3)-oxo-hexa(acetato)tri(aqua)iron(II)diiron(III), first with straight chain carboxylic acids and then with Schiff bases. The complexes were characterized by elemental analyses, molecular weight determinations and spectral (electronic, infrared, FAB mass, Mössbauer and powder XRD) studies. Molar conductance measurements indicated the complexes to be non-electrolytes in nitrobenzene. Bridging nature of carboxylate and Schiff base anions in the complexes was established by their infrared spectra. Mössbauer spectroscopic studies indicated two quadrupole-split doublets due to Fe(II) and Fe(III) ions at 80, 200 and 295K, confirming the complexes are mixed-valence species. This was also supported by the observed electronic spectra of the complexes. Magnetic susceptibility measurements displayed octahedral geometry around iron in mixed-valence state and a net antiferromagnetic exchange coupling via μ-oxo atom. Trinuclear nature of the complexes was confirmed by their molecular weight determination and FAB mass spectra. A plausible structure for these complexes has been established on the basis of spectral and magnetic moment data.

  18. Synthesis and spectral characterization of trinuclear, oxo-centered, carboxylate-bridged, mixed-valence iron complexes with Schiff bases

    NASA Astrophysics Data System (ADS)

    Singh, Atresh Kumar; Singh, Alok Kumar

    2012-10-01

    Some novel trinuclear, oxo-centered, carboxylate-bridged, mixed-valence iron complexes of the general formula [Fe3O(OOCR)3(SB)3L3] (where R = C13H27, C15H31 or C17H35, HSB = Schiff bases and L = Ethanol) have been synthesized by the stepwise substitutions of acetate ions from μ3-oxo-hexa(acetato)tri(aqua)iron(II)diiron(III), first with straight chain carboxylic acids and then with Schiff bases. The complexes were characterized by elemental analyses, molecular weight determinations and spectral (electronic, infrared, FAB mass, Mössbauer and powder XRD) studies. Molar conductance measurements indicated the complexes to be non-electrolytes in nitrobenzene. Bridging nature of carboxylate and Schiff base anions in the complexes was established by their infrared spectra. Mössbauer spectroscopic studies indicated two quadrupole-split doublets due to Fe(II) and Fe(III) ions at 80, 200 and 295 K, confirming the complexes are mixed-valence species. This was also supported by the observed electronic spectra of the complexes. Magnetic susceptibility measurements displayed octahedral geometry around iron in mixed-valence state and a net antiferromagnetic exchange coupling via μ-oxo atom. Trinuclear nature of the complexes was confirmed by their molecular weight determination and FAB mass spectra. A plausible structure for these complexes has been established on the basis of spectral and magnetic moment data.

  19. Simulating Ru L3-Edge X-ray Absorption Spectroscopy with Time-Dependent Density Functional Theory: Model Complexes and Electron Localization in Mixed-Valence Metal Dimers

    SciTech Connect

    Kuiken, Benjamin E. Van; Valiev, Marat; Daifuku, Stephanie L.; Bannan, Caitlin; Strader, Matthew L.; Cho, Hana; Huse, Nils; Schoenlein, Robert W.; Govind, Niranjan; Khalil, Munira

    2013-04-26

    Ruthenium L3-edge X-ray absorption (XA) spectroscopy probes unoccupied 4d orbitals of the metal atom and is increasingly being used to investigate the local electronic structure in ground and excited electronic states of Ru complexes. The simultaneous development of computational tools for simulating Ru L3-edge spectra is crucial for interpreting the spectral features at a molecular level. This study demonstrates that time-dependent density functional theory (TDDFT) is a viable and predictive tool for simulating ruthenium L3-edge XA spectroscopy. We systematically investigate the effects of exchange correlation functional and implicit and explicit solvent interactions on a series of RuII and RuIII complexes in their ground and electronic excited states. The TDDFT simulations reproduce all of the experimentally observed features in Ru L3-edge XA spectra within the experimental resolution (0.4 eV). Our simulations identify ligand-specific charge transfer features in complicated Ru L3-edge spectra of [Ru(CN)6]4- and RuII polypyridyl complexes illustrating the advantage of using TDDFT in complex systems. We conclude that the B3LYP functional most accurately predicts the transition energies of charge transfer features in these systems. We use our TDDFT approach to simulate experimental Ru L3-edge XA spectra of transition metal mixed-valence dimers of the form [(NC)5MII-CN-RuIII(NH3)5] (where M = Fe or Ru) dissolved in water. Our study determines the spectral signatures of electron delocalization in Ru L3-edge XA spectra. We find that the inclusion of explicit solvent molecules is necessary for reproducing the spectral features and the experimentally determined valencies in these mixed-valence complexes. This study validates the use of TDDFT for simulating Ru 2p excitations using popular quantum chemistry codes and providing a powerful interpretive tool for equilibrium and ultrafast Ru L3-edge XA spectroscopy.

  20. Magnetic heterogeneity of biological systems.

    PubMed

    Piruzyan, L A; Kuznetsov, A A; Chikov, V M

    1980-01-01

    In biological systems nonuniformity of magnetic susceptibility, magnetic heterogeneity, is a reflection of their physical-chemical and morphological heterogeneity, A characteristic value of heterogeneity is delta K approximately 10(-6)-10(-7) CGS units, a quantitative measurement of susceptibility of cells and other small objects, may give qualitatively new information about their life processes. Patterns and features of movement of small biological objects and liquids affected by magnetic forces were studied. A method was developed for measuring magnetic susceptibility of single microobjects based on observation of movement of the objects in a strong heterogeneous field with parameters (formula: see text) grad H2/2 approximately 10(9)-10(10) Oe2/cm. This method does not require knowing the distribution of the field along the path of movement of the particles, and does not require preliminary calibration. Movement of human erythrocytes, rat hepatocytes, and starch granules in liquids at a point of entry into a gap with the field was observed experimentally. With sufficiently large fields Ho approximately (1-2) x 10(4) Oe, the value of the magnetic force was enough to change the rate of sedimentation movement of the objects appreciably (up to stopping it). This made it possible to compute the value delta K for cells approximately 10(-7)-10(-8) CGS units and to obtain the value of K for starch granules (-0.80 x 10(-6) cGS units). In connection with the fact that sensitivity to gravity in plants is coupled with a disturbance of the intracellular starch granules under the influence of gravity, certain problems of stimulating the effect of gravity on plants by magnetic forces were studied. Noncontact force effect on magnetically heterogeneous biological objects is a promising instrument for biophysical studies.

  1. Investigating vibrational anharmonic couplings in cyanide-bridged transition metal mixed valence complexes using two-dimensional infrared spectroscopy

    SciTech Connect

    Slenkamp, Karla M.; Lynch, Michael S.; Van Kuiken, Benjamin E.; Brookes, Jennifer F.; Bannan, Caitlin C.; Daifuku, Stephanie L.; Khalil, Munira

    2014-02-28

    Using polarization-selective two-dimensional infrared (2D IR) spectroscopy, we measure anharmonic couplings and angles between the transition dipole moments of the four cyanide stretching (ν{sub CN}) vibrations found in [(NH{sub 3}){sub 5}Ru{sup III}NCFe{sup II}(CN){sub 5}]{sup −} (FeRu) dissolved in D{sub 2}O and formamide and [(NC){sub 5}Fe{sup II}CNPt{sup IV}(NH{sub 3}){sub 4}NCFe{sup II}(CN){sub 5}]{sup 4−} (FePtFe) dissolved in D{sub 2}O. These cyanide-bridged transition metal complexes serve as model systems for studying the role of high frequency vibrational modes in ultrafast photoinduced charge transfer reactions. Here, we focus on the spectroscopy of the ν{sub CN} modes in the electronic ground state. The FTIR spectra of the ν{sub CN} modes of the bimetallic and trimetallic systems are strikingly different in terms of frequencies, amplitudes, and lineshapes. The experimental 2D IR spectra of FeRu and FePtFe and their fits reveal a set of weakly coupled anharmonic ν{sub CN} modes. The vibrational mode anharmonicities of the individual ν{sub CN} modes range from 14 to 28 cm{sup −1}. The mixed-mode anharmonicities range from 2 to 14 cm{sup −1}. In general, the bridging ν{sub CN} mode is most weakly coupled to the radial ν{sub CN} mode, which involves the terminal CN ligands. Measurement of the relative transition dipole moments of the four ν{sub CN} modes reveal that the FeRu molecule is almost linear in solution when dissolved in formamide, but it assumes a bent geometry when dissolved in D{sub 2}O. The ν{sub CN} modes are modelled as bilinearly coupled anharmonic oscillators with an average coupling constant of 6 cm{sup −1}. This study elucidates the role of the solvent in modulating the molecular geometry and the anharmonic vibrational couplings between the ν{sub CN} modes in cyanide-bridged transition metal mixed valence complexes.

  2. Electronic Structure and Bonding in Co-Based Single and Mixed Valence Oxides: A Quantum Chemical Perspective.

    PubMed

    Singh, Vijay; Major, Dan Thomas

    2016-04-01

    The mixed valence cobalt oxide, Co3O4, is a potential candidate as a photovoltaic (PV) material, which also exhibits intriguing chemical and catalytic properties. Here, we present a comparative study of the electronic, magnetic, and chemical bonding properties of mixed valence Co3O4 (i.e., Co(2+/3+)) with the related single valence CoO (i.e., Co(2+)) and Co2O3 (i.e., Co(3+)) oxides using density functional theory (DFT). We have employed a range of theoretical methods, including pure DFT, DFT+U, and a range-separated exchange-correlation functional (HSE06). We compare the electronic structure and band gap of the oxide materials, with available photoemission spectroscopy and optical band gaps. Our calculations suggest that the bonding between Co(3+) and O(2-) ions in Co2O3 and Co3O4 and Co(2+) and O(2-) ions in CoO and Co3O4 are rather different. We find that Co2O3 and Co3O4 are weakly correlated materials, whereas CoO is a strongly correlated material. Furthermore, our computed one-electron energy level diagrams reveal that strong Co-O antibonding states are present at the top of the valence band for all the cobalt oxides, hinting at a defect tolerant capacity in these materials. These results, which give a detailed picture of the chemical bonding in related single and mixed valence cobalt oxides, may serve as a guide to enhance the PV or photoelectrochemical activity of Co3O4, by reducing its internal defect states or changing its electronic structure by doping or alloying with suitable elements. PMID:27010797

  3. Electronic Structure and Bonding in Co-Based Single and Mixed Valence Oxides: A Quantum Chemical Perspective.

    PubMed

    Singh, Vijay; Major, Dan Thomas

    2016-04-01

    The mixed valence cobalt oxide, Co3O4, is a potential candidate as a photovoltaic (PV) material, which also exhibits intriguing chemical and catalytic properties. Here, we present a comparative study of the electronic, magnetic, and chemical bonding properties of mixed valence Co3O4 (i.e., Co(2+/3+)) with the related single valence CoO (i.e., Co(2+)) and Co2O3 (i.e., Co(3+)) oxides using density functional theory (DFT). We have employed a range of theoretical methods, including pure DFT, DFT+U, and a range-separated exchange-correlation functional (HSE06). We compare the electronic structure and band gap of the oxide materials, with available photoemission spectroscopy and optical band gaps. Our calculations suggest that the bonding between Co(3+) and O(2-) ions in Co2O3 and Co3O4 and Co(2+) and O(2-) ions in CoO and Co3O4 are rather different. We find that Co2O3 and Co3O4 are weakly correlated materials, whereas CoO is a strongly correlated material. Furthermore, our computed one-electron energy level diagrams reveal that strong Co-O antibonding states are present at the top of the valence band for all the cobalt oxides, hinting at a defect tolerant capacity in these materials. These results, which give a detailed picture of the chemical bonding in related single and mixed valence cobalt oxides, may serve as a guide to enhance the PV or photoelectrochemical activity of Co3O4, by reducing its internal defect states or changing its electronic structure by doping or alloying with suitable elements.

  4. The first example of a mixed valence ternary compound of silver with random distribution of Ag(I) and Ag(II) cations.

    PubMed

    Mazej, Zoran; Michałowski, Tomasz; Goreshnik, Evgeny A; Jagličić, Zvonko; Arčon, Iztok; Szydłowska, Jadwiga; Grochala, Wojciech

    2015-06-28

    The reaction between colourless AgSbF6 and sky-blue Ag(SbF6)2 (molar ratio 2 : 1) in gaseous HF at 323 K yields green Ag3(SbF6)4, a new mixed-valence ternary fluoride of silver. Unlike in all other Ag(I)/Ag(II) systems known to date, the Ag(+) and Ag(2+) cations are randomly distributed on a single 12b Wyckoff position at the 4̄ axis of the I4̄3d cell. Each silver forms four short (4 × 2.316(7) Å) and four long (4 × 2.764(6) Å) contacts with the neighbouring fluorine atoms. The valence bond sum analysis suggests that such coordination would correspond to a severely overbonded Ag(I) and strongly underbonded Ag(II). Thorough inspection of thermal ellipsoids of the fluorine atoms closest to Ag centres reveals their unusual shape, indicating that silver atoms must in fact have different local coordination spheres; this is not immediately apparent from the crystal structure due to static disorder of fluorine atoms. The Ag K-edge XANES analysis confirmed that the average oxidation state of silver is indeed close to +1⅓. The optical absorption spectra lack features typical of a metal thus pointing out to the semiconducting nature of Ag3(SbF6)4. Ag3(SbF6)4 is magnetically diluted and paramagnetic (μ(eff) = 1.9 μ(B)) down to 20 K with a very weak temperature independent paramagnetism. Below 20 K weak antiferromagnetism is observed (Θ = -4.1 K). Replacement of Ag(I) with potassium gives K(I)2Ag(II)(SbF6)4 which is isostructural to Ag(I)2Ag(II)(SbF6)4. Ag3(SbF6)4 is a genuine mixed-valence Ag(I)/Ag(II) compound, i.e. Robin and Day Class I system (localized valences), despite Ag(I) and Ag(II) adopting the same crystallographic position. PMID:25815902

  5. Mixed-valence iron minerals on Venus: Fe(2+)-Fe(3+) oxides and oxy-silicates formed by surface-atmosphere interactions

    NASA Technical Reports Server (NTRS)

    Burns, Roger G.; Straub, Darcy W.

    1992-01-01

    Inferences from these investigations are that Fe(3+)-bearing minerals such as hematite magnesioferrite, acmite, and epidote are thermodynamically unstable, and that magnetite is the predominant mixed-valence iron oxide mineral on venus. Recently, the Fe(2+)-Fe(3+) silicate mineral laihunite was proposed to be a reaction product of olivine with the venusian atmosphere. This possibility is discussed further here. We suggest that other mixed-valence Fe(2+)-Fe(3+)-Oz-OH(-) silicates could also result from surface-atmosphere interactions on Venus. Topics discussed include the following: (1) conversion of hematite to magnetite; (2) stability of laihunite; (3) the possible existence of oxy-amphiboles and oxy-micas on Venus; and (4) other mixed-valence Fe(2+)-Fe(3+) silicates likely to exist on Venus.

  6. Metal-metal coupling elements of mixed-valence pentaammineruthenium dimers: The hole-transfer superexchange case

    NASA Astrophysics Data System (ADS)

    Naklicki, M. L.; Evans, C. E. B.; Crutchley, R. J.

    1997-03-01

    The extent of metal-metal coupling in the mixed-valence complexes [Ru(NH 3) 52(μ-L)] 3+], where L is 2,5-dimethyl-(Me 2dicyd 2-), 2,5-dichloro- (Cl 2dicyd 2-), 2,3,5,6-tetrachloro- (Cl 4dicyd 2-) or unsubstituted (dicyd 2-) 1,4-dicyanamidobenzene dianion, was evaluated by comparing theoretical values of metal-metal coupling elements with estimates of the free energy of resonance exchange which were derived from the free energies of comproportionation. Poor agreement was found with the Hush model; however, an excellent correlation was seen with the model of Creutz, Newton and Sutin (CNS). It would appear that the CNS model is remarkably successful in describing the extent of metal-metal coupling for the strongly coupled valence trapped complexes of this study.

  7. Tetrathiafulvalene-based mixed-valence acceptor-donor-acceptor triads: a joint theoretical and experimental approach.

    PubMed

    Calbo, Joaquín; Aragó, Juan; Otón, Francisco; Lloveras, Vega; Mas-Torrent, Marta; Vidal-Gancedo, José; Veciana, Jaume; Rovira, Concepció; Ortí, Enrique

    2013-12-01

    This work presents a joint theoretical and experimental characterisation of the structural and electronic properties of two tetrathiafulvalene (TTF)-based acceptor-donor-acceptor triads (BQ-TTF-BQ and BTCNQ-TTF-BTCNQ; BQ is naphthoquinone and BTCNQ is benzotetracyano-p-quinodimethane) in their neutral and reduced states. The study is performed with the use of electrochemical, electron paramagnetic resonance (EPR), and UV/Vis/NIR spectroelectrochemical techniques guided by quantum-chemical calculations. Emphasis is placed on the mixed-valence properties of both triads in their radical anion states. The electrochemical and EPR results reveal that both BQ-TTF-BQ and BTCNQ-TTF-BTCNQ triads in their radical anion states behave as class-II mixed-valence compounds with significant electronic communication between the acceptor moieties. Density functional theory calculations (BLYP35/cc-pVTZ), taking into account the solvent effects, predict charge-localised species (BQ(.-)-TTF-BQ and BTCNQ(.-)-TTF-BTCNQ) as the most stable structures for the radical anion states of both triads. A stronger localisation is found both experimentally and theoretically for the BTCNQ-TTF-BTCNQ anion, in accordance with the more electron-withdrawing character of the BTCNQ acceptor. CASSCF/CASPT2 calculations suggest that the low-energy, broad absorption bands observed experimentally for the BQ-TTF-BQ and BTCNQ-TTF-BTCNQ radical anions are associated with the intervalence charge transfer (IV-CT) electronic transition and two nearby donor-to-acceptor CT excitations. The study highlights the molecular efficiency of the electron-donor TTF unit as a molecular wire connecting two acceptor redox centres.

  8. Effects of ion aggregation on the intervalence transfer band of the mixed-valence biferrocenium cation in solution

    SciTech Connect

    Lowery, M.D.; Hammack, W.S.; Drickamer, H.G.; Hendrickson, D.N.

    1987-12-23

    The concentration dependence of the energy (E/sup op/) of the intervalence transfer (IT) electronic absorption band of mixed-valence biferrocenium triiodide dissolved in either nitrobenzene or dichloromethane is examined. In nitrobenzene, E/sup op/ increases rapidly from approx. 5.57 to approx. 6.05 x 10/sup 3/ cm/sup -1/ in the 0.24-0.4 mM range, whereupon further increases in the concentration of biferrocenium triiodide lead to E/sup op/ increasing more gradually to a value approx. 6.3 x 10/sup 3/ cm/sup -1/ at 24 mM. On the other hand, the full width at half maximum (..delta.. anti v/sub 1/2) and the transition moment of the IT band decrease with increasing concentration for biferrocenium triiodide in nitrobenzene. E/sup op/ increases, ..delta.. anti v/sub 1/2 remains constant, and the transition moment of the IT band increases with increasing concentration for biferrocenium triiodide in dichloromethane in the more limited range of 0.30-0.95 mM. These concentration dependencies of the IT band for biferrocenium triiodide are attributable to variable degrees of ion aggregation in solution. The concentration dependencies of the electrical conductivity of solutions of biferrocenium triiodide in either nitrobenzene or dichloromethane substantiate this proposal. IT band contours obtained at different concentrations are fit to the PKS vibronic model to yield parameters that characterize the electronic and vibronic coupling within the mixed-valence biferrocenium cation.

  9. Charge, orbital and spin ordering phenomena in the mixed valence manganite (NaMn3+(3))(Mn3+(2)Mn4+(2))O12.

    PubMed

    Prodi, A; Gilioli, E; Gauzzi, A; Licci, F; Marezio, M; Bolzoni, F; Huang, Q; Santoro, A; Lynn, J W

    2004-01-01

    Mixed-valence manganites with the ABO3 perovskite structure display a variety of magnetic and structural transitions, dramatic changes of electrical conductivity and magnetoresistance effects. The physical properties vary with the relative concentration of Mn3+ and Mn4+ in the octahedral corner-sharing network, and the proportion of these two cations is usually changed by doping the trivalent large A cation (for example, La3+) with divalent cations. As the dopant and the original cation have, in general, different sizes, and as they are distributed randomly in the structure, such systems are characterized by local distortions that make it difficult to obtain direct information about their crystallographic and physical properties. On the other hand, the double oxides of formula AA'3Mn4O12 contain a perovskite-like network of oxygen octahedra centred on the Mn cations, coupled with an ordered arrangement of the A and A' cations, whose valences control the proportion of Mn3+ and Mn4+ in the structure. The compound investigated in this work, (NaMn3+(3))(Mn3+(2)Mn4+(2))O12, contains an equal number of Mn3+ and Mn4+ in the octahedral sites. We show that the absence of disorder enables the unambiguous determination of symmetry, the direct observation of full, or nearly full, charge ordering of Mn3+ and Mn4+ in distinct crystallographic sites, and a nearly perfect orbital ordering of the Mn3+ octahedra.

  10. Interoperability of heterogeneous distributed systems

    NASA Astrophysics Data System (ADS)

    Zaschke, C.; Essendorfer, B.; Kerth, C.

    2016-05-01

    To achieve knowledge superiority in today's operations interoperability is the key. Budget restrictions as well as the complexity and multiplicity of threats combined with the fact that not single nations but whole areas are subject to attacks force nations to collaborate and share information as appropriate. Multiple data and information sources produce different kinds of data, real time and non-real time, in different formats that are disseminated to the respective command and control level for further distribution. The data is most of the time highly sensitive and restricted in terms of sharing. The question is how to make this data available to the right people at the right time with the right granularity. The Coalition Shared Data concept aims to provide a solution to these questions. It has been developed within several multinational projects and evolved over time. A continuous improvement process was established and resulted in the adaptation of the architecture as well as the technical solution and the processes it supports. Coming from the idea of making use of existing standards and basing the concept on sharing of data through standardized interfaces and formats and enabling metadata based query the concept merged with a more sophisticated service based approach. The paper addresses concepts for information sharing to facilitate interoperability between heterogeneous distributed systems. It introduces the methods that were used and the challenges that had to be overcome. Furthermore, the paper gives a perspective how the concept could be used in the future and what measures have to be taken to successfully bring it into operations.

  11. Theoretical and experimental study of high-magnetic-field XMCD spectra at the L2,3 absorption edges of mixed-valence rare-earth compounds

    NASA Astrophysics Data System (ADS)

    Kotani, Akio; Matsuda, Yasuhiro H.; Nojiri, Hiroyuki

    2009-11-01

    X-ray magnetic circular dichroism(XMCD) spectra at the L2,3 edges of mixed-valence rare-earth compounds in high magnetic fields are studied both theoretically and experimentally. The theoretical study is based on a new framework proposed recently by Kotani. The Zeeman splitting of 4f states, the mixed-valence character of 4f states, and the 4f-5d exchange interaction are incorporated into a single impurity Anderson model. New XMCD experiments in high magnetic fields up to 40 T are carried out for the mixed-valence compounds EuNi2(Si0.18Ge0.82)2 and YbInCu4 by using a miniature pulsed magnet, which was developed recently by Matsuda et al. The XMCD data are taken at 5 K by transmission measurements for incident X-rays with ± helicities at BL39XU in SPring-8. After giving a survey on recent developments in the theory of XMCD spectra for mixed-valence Ce and Yb compounds, we calculate the XMCD spectra of YbInCu4 at the field-induced valence transition around 32 T by applying the recent theoretical framework and by newly introducing at 32 T a discontinuous change in the Yb 4f level and that in the hybridization strength between the Yb 4f and conduction electrons. The calculated results are compared with the experimental ones.

  12. Intramolecular C-H bond activation and redox isomerization across two-electron mixed valence diiridium cores.

    SciTech Connect

    Esswein, A. J.; Veige, A. S.; Piccoli, P. M. B.; Schultz, A. J.; Nocera, D. G.; MIT

    2008-03-24

    Metal-metal cooperativity enables the reaction of carbon-based substrates at diiridium two-electron mixed valence centers. Arylation of Ir{sub 2}{sup 0,II}(tfepma){sub 3}Cl{sub 2} (1) (tfepma = bis[(bistrifluoroethoxy)phosphino]methylamine) with RMgBr (R = C{sub 6}H{sub 5} and C{sub 6}D{sub 5}) is followed by C-H bond activation to furnish the bridging benzyne complex Ir{sub 2}II,II(tfepma){sub 3}({mu}-C{sub 6}H4)(C{sub 6}H{sub 5})H (2), as the kinetic product. At ambient temperature, 2 isomerizes to Ir{sub 2}{sup I,III}(tfepma){sub 3}({mu}-C{sub 6}H4)(C{sub 6}H{sub 5})H (3) (k{sub obs} = 9.57 {+-} 0.10 x 10{sup -5} s{sup -1} at 31.8 C, {Delta}H{sup {+-}} = 21.7 {+-} 0.3 kcal/mol, {Delta}S{sup {+-}} = -7.4 {+-} 0.9 eu), in which the benzyne moiety is conserved and the Ir{sup III} center is ligated by terminal hydride and phenyl groups. The same reaction course is observed for arylation of 1 with C{sub 6}D{sub 5}MgBr to produce 2-d{sub 10} and 3-d{sub 10} accompanied by an inverse isotope effect, k{sub h}/k{sub d} = 0.44 (k{sub obs} = 2.17 {+-} 0.10 x 10{sup -4} s{sup -1} in C{sub 6}D{sub 6} solution at 31.8 C, {Delta}H{sup {+-}} = 24.9 {+-} 0.7 kcal/mol, {Delta}S{sup {+-}} = -6.4 {+-} 2.4 eu). 2 reacts swiftly with hydrogen to provide Ir{sub 2}{sup II,II}(tfepma){sub 3}H{sub 4} as both the syn and anti isomers (4-syn and 4-anti, respectively). The hydrides of 4-syn were directly located by neutron diffraction analysis. X-ray crystallographic examination of 2, 2-d{sub 10}, 3, and 4-syn indicates that cooperative reactivity at the bimetallic diiridium core is facilitated by the ability of the two-electron mixed valence framework to accommodate the oxidation state changes and ligand rearrangements attendant to the reaction of the substrate.

  13. Manganese L-edge X-ray absorption spectroscopy of manganese catalase from Lactobacillus plantarum and mixed valence manganese complexes

    SciTech Connect

    Grush, M.M.; Chen, J.; George, S.J.

    1996-01-10

    The first Mn L-edge absorption spectra of a Mn metalloprotein are presented in this paper. Both reduced and superoxidized Mn catalase have been examined by fluorescence-detected soft X-ray absorption spectroscopy, and their Mn L-edge spectra are dramatically different. The spectrum of reduced Mn(II)Mn(II) catalase has been interpreted by ligand field atomic multiplet calculations and by comparison to model compound spectra. The analysis finds a 10 Dq value of nearly 1.1 eV, consistent with coordination by predominately nitrogen and oxygen donor ligands. For interpretation of mixed valence Mn spectra, an empirical simulation procedure based on the addition of homovalent model compound spectra has been developed and was tested on a variety of Mn complexes and superoxidized Mn catalase. This routine was also used to determine the oxidation state composition of the Mn in [Ba{sub 8}Na{sub 2}ClMn{sub 16}(OH){sub 8}(CO{sub 3}){sub 4}L{sub 8}] .53 H{sub 2}O (L=1,3-diamino-2-hydroxypropane-N,N,N`N`-tetraacetic acid). 27 refs., 6 figs.

  14. Sunlight-driven formation and dissociation of a dynamic mixed-valence thallium(III)/thallium(I) porphyrin complex.

    PubMed

    Ndoyom, Victoria; Fusaro, Luca; Dorcet, Vincent; Boitrel, Bernard; Le Gac, Stéphane

    2015-03-16

    Inspired by a Newton's cradle device and interested in the development of redox-controllable bimetallic molecular switches, a mixed-valence thallium(III)/thallium(I) bis-strap porphyrin complex, with Tl(III) bound out of the plane of the N core and Tl(I) hung to a strap on the opposite side, was formed by the addition of TlOAc to the free base and exposure to indirect sunlight. In this process, oxygen photosensitization by the porphyrin allows the oxidation of Tl(I) to Tl(III). The bimetallic complex is dynamic as the metals exchange their positions symmetrically to the porphyrin plane with Tl(III) funneling through the macrocycle. Further exposure of the complex to direct sunlight leads to thallium dissociation and to total recovery of the free base. Hence, the porphyrin plays a key role at all stages of the cycle of the complex: It hosts two metal ions, and by absorbing light, it allows the formation and dissociation of Tl(III). These results constitute the basis for the further design of innovative light-driven bimetallic molecular devices.

  15. New mixed-valence chromium structure type: NH{sub 4}Cr(CrO{sub 4}){sub 2}

    SciTech Connect

    Casari, Barbara M. . E-mail: casari@chem.gu.se; Wingstrand, Erica; Langer, Vratislav

    2006-01-15

    Synthesis and crystal structure of a new structure type of mixed Cr(III)/Cr(VI) chromates is reported. NH{sub 4}Cr(CrO{sub 4}){sub 2} was prepared from CrO{sub 3} in the presence of (NH{sub 4}){sub 2}Ce(NO{sub 3}){sub 6}. Since this is the first preparation of mixed valence ternary chromium oxides from aqueous solution, a reaction pathway for this synthesis is suggested. The crystal structure of NH{sub 4}Cr(CrO{sub 4}){sub 2} has been determined from three-dimensional X-ray data collected at low temperature, 173K. The structure belongs to the orthorhombic space group Pnma, with a=14.5206(10), b=5.4826(4), c=8.7041(7)A and Z=4. The title compound consists of corner-sharing chromium(III) octahedra and chromium(VI) tetrahedra forming a three-dimensional network with the composition [Cr(CrO{sub 4}){sub 2}]{sub n}{sup n-}, containing channels in which zigzag rows of ammonium ions balance the net charge.

  16. High-spin ground states via electron delocalization in mixed-valence imidazolate-bridged divanadium complexes.

    PubMed

    Bechlars, Bettina; D'Alessandro, Deanna M; Jenkins, David M; Iavarone, Anthony T; Glover, Starla D; Kubiak, Clifford P; Long, Jeffrey R

    2010-05-01

    The field of molecular magnetism has grown tremendously since the discovery of single-molecule magnets, but it remains centred around the superexchange mechanism. The possibility of instead using a double-exchange mechanism (based on electron delocalization rather than Heisenberg exchange through a non-magnetic bridge) presents a tantalizing prospect for synthesizing molecules with high-spin ground states that are well isolated in energy. We now demonstrate that magnetic double exchange can be sustained by simple imidazolate bridging ligands, known to be well suited for the construction of coordination clusters and solids. A series of mixed-valence molecules of the type [(PY5Me(2))V(II)(micro-L(br)) V(III)(PY5Me(2))](4+) were synthesized and their electron delocalization probed through cyclic voltammetry and spectroelectrochemistry. Magnetic susceptibility data reveal a well-isolated S = 5/2 ground state arising from double exchange for [(PY5Me(2))(2)V(2)(micro-5,6-dimethylbenzimidazolate)](4+). Combined modelling of the magnetic data and spectral analysis leads to an estimate of the double-exchange parameter of B = 220 cm(-1) when vibronic coupling is taken into account.

  17. Role of the coordinating histidine in altering the mixed valency of Cu(A): an electron nuclear double resonance-electron paramagnetic resonance investigation.

    PubMed Central

    Lukoyanov, Dmitriy; Berry, Steven M; Lu, Yi; Antholine, William E; Scholes, Charles P

    2002-01-01

    The binuclear Cu(A) site engineered into Pseudomonas aeruginosa azurin has provided a Cu(A)-azurin with a well-defined crystal structure and a CuSSCu core having two equatorial histidine ligands, His120 and His46. The mutations His120Asn and His120Gly were made at the equatorial His120 ligand to understand the histidine-related modulation to Cu(A), notably to the valence delocalization over the CuSSCu core. For these His120 mutants Q-band electron nuclear double resonance (ENDOR) and multifrequency electron paramagnetic resonance (EPR) (X, C, and S-band), all carried out under comparable cryogenic conditions, have provided markedly different electronic measures of the mutation-induced change. Q-band ENDOR of cysteine C(beta) protons, of weakly dipolar-coupled protons, and of the remaining His46 nitrogen ligand provided hyperfine couplings that were like those of other binuclear mixed-valence Cu(A) systems and were essentially unperturbed by the mutation at His120. The ENDOR findings imply that the Cu(A) core electronic structure remains unchanged by the His120 mutation. On the other hand, multifrequency EPR indicated that the H120N and H120G mutations had changed the EPR hyperfine signature from a 7-line to a 4-line pattern, consistent with trapped-valence, Type 1 mononuclear copper. The multifrequency EPR data imply that the electron spin had become localized on one copper by the His120 mutation. To reconcile the EPR and ENDOR findings for the His120 mutants requires that either: if valence localization to one copper has occurred, the spin density on the cysteine sulfurs and the remaining histidine (His46) must remain as it was for a delocalized binuclear Cu(A) center, or if valence delocalization persists, the hyperfine coupling for one copper must markedly diminish while the overall spin distribution on the CuSSCu core is preserved. PMID:11964261

  18. Exchange Interactions on the Highest-Spin Reported Molecule: the Mixed-Valence Fe42 Complex

    PubMed Central

    Aravena, Daniel; Venegas-Yazigi, Diego; Ruiz, Eliseo

    2016-01-01

    The finding of high-spin molecules that could behave as conventional magnets has been one of the main challenges in Molecular Magnetism. Here, the exchange interactions, present in the highest-spin molecule published in the literature, Fe42, have been analysed using theoretical methods based on Density Functional Theory. The system with a total spin value S = 45 is formed by 42 iron centres containing 18 high-spin FeIII ferromagnetically coupled and 24 diamagnetic low-spin FeII ions. The bridging ligands between the two paramagnetic centres are two cyanide ligands coordinated to the diamagnetic FeII cations. Calculations were performed using either small Fe4 or Fe3 models or the whole Fe42 complex, showing the presence of two different ferromagnetic couplings between the paramagnetic FeIII centres. Finally, Quantum Monte Carlo simulations for the whole system were carried out in order to compare the experimental and simulated magnetic susceptibility curves from the calculated exchange coupling constants with the experimental one. This comparison allows for the evaluation of the accuracy of different exchange-correlation functionals to reproduce such magnetic properties. PMID:27033418

  19. Porous layered and open-framework mixed-valence copper tellurites

    NASA Astrophysics Data System (ADS)

    Markovski, Mishel R.; Siidra, Oleg I.; Kayukov, Roman A.; Nazarchuk, Evgeni W.

    2016-11-01

    |Cu+Cl3|[Cu2+2(TeO3)] (1), |Cu+1.7Cl3.8|[Cu2+4O(TeO3)2] (2) and Tl+2[Cu2+2Te6+Te4+6O18] (3) were obtained by CVT and hydrothermal methods in CuCl-CuCl2-TeO2 and Tl2CO3-CuO-TeO2 systems. 1 demonstrates layered topology with pores (1×0.65 nm), whereas 2 has open-framework structural architecture with two-dimensional system of channels (1.16×0.74 nm). Channels in open-framework of 3 are occupied by Tl+ cations. 'Host-guest' structural organization of 1 and 2 with host Cu2+-tellurite units of different dimensionality formed by oxocentered OCu4 tetrahedra and OCu2Te triangles and guest Cu+-chloride species is the result of formation from gases in CVT reactions. Oxocentered units determine basic topologies of the structures of 1 and 2 and influence their stability and properties. [Te6+Te4+6O18]6- polytellurite-tellurate framework in 3 can be represented as consisting of Kagome-like layers.

  20. Exchange Interactions on the Highest-Spin Reported Molecule: the Mixed-Valence Fe42 Complex

    NASA Astrophysics Data System (ADS)

    Aravena, Daniel; Venegas-Yazigi, Diego; Ruiz, Eliseo

    2016-04-01

    The finding of high-spin molecules that could behave as conventional magnets has been one of the main challenges in Molecular Magnetism. Here, the exchange interactions, present in the highest-spin molecule published in the literature, Fe42, have been analysed using theoretical methods based on Density Functional Theory. The system with a total spin value S = 45 is formed by 42 iron centres containing 18 high-spin FeIII ferromagnetically coupled and 24 diamagnetic low-spin FeII ions. The bridging ligands between the two paramagnetic centres are two cyanide ligands coordinated to the diamagnetic FeII cations. Calculations were performed using either small Fe4 or Fe3 models or the whole Fe42 complex, showing the presence of two different ferromagnetic couplings between the paramagnetic FeIII centres. Finally, Quantum Monte Carlo simulations for the whole system were carried out in order to compare the experimental and simulated magnetic susceptibility curves from the calculated exchange coupling constants with the experimental one. This comparison allows for the evaluation of the accuracy of different exchange-correlation functionals to reproduce such magnetic properties.

  1. Laser-excited luminescence and absorption study of mixed valence for K 2Pt(CN) 4—K 2Pt(CN) 6 crystals

    NASA Astrophysics Data System (ADS)

    Kasi Viswanath, A.; Smith, Wayne L.; Patterson, H.

    1982-04-01

    Crystals of K 2Pt(CN) 6 doped with Pt(CN) 2-4 show an absorption band at 337 nm which is assigned as a mixed-valence (MV) transition from Pt (II) to Pt(IV). From a Hush model analysis, the absorption band is interpreted to be class II in the Day—Robin scheme. When the MV band is laser excited at 337 nm, emmision is observed from Pt(CN) 2-4 clusters.

  2. Integrating CLIPS applications into heterogeneous distributed systems

    NASA Technical Reports Server (NTRS)

    Adler, Richard M.

    1991-01-01

    SOCIAL is an advanced, object-oriented development tool for integrating intelligent and conventional applications across heterogeneous hardware and software platforms. SOCIAL defines a family of 'wrapper' objects called agents, which incorporate predefined capabilities for distributed communication and control. Developers embed applications within agents and establish interactions between distributed agents via non-intrusive message-based interfaces. This paper describes a predefined SOCIAL agent that is specialized for integrating C Language Integrated Production System (CLIPS)-based applications. The agent's high-level Application Programming Interface supports bidirectional flow of data, knowledge, and commands to other agents, enabling CLIPS applications to initiate interactions autonomously, and respond to requests and results from heterogeneous remote systems. The design and operation of CLIPS agents are illustrated with two distributed applications that integrate CLIPS-based expert systems with other intelligent systems for isolating and mapping problems in the Space Shuttle Launch Processing System at the NASA Kennedy Space Center.

  3. Optical properties of Eu{sup 2+}/Eu{sup 3+} mixed valence, silicon nitride based materials

    SciTech Connect

    Kate, Otmar M. ten; Vranken, Thomas; Kolk, Erik van der; Jansen, Antonius P.J.; Hintzen, Hubertus T.

    2014-05-01

    Eu{sub 2}SiN{sub 3}, a mixed valence europium nitridosilicate, has been prepared via solid-state reaction synthesis and its oxidation behavior and optical properties have been determined. Furthermore, the stability of several isostructural compounds of the type M{sup 2+}L{sup 3+}SiN{sub 3} has been predicted by using the density functional theory calculations, and verified by the actual synthesis of CaLaSiN{sub 3}, CaEuSiN{sub 3} and EuLaSiN{sub 3}. The band gap of CaLaSiN{sub 3} was found around 3.2 eV giving the material its yellow color. Eu{sub 2}SiN{sub 3} on the other hand is black due to a combination of the 4f–5d absorption band of Eu{sup 2+} and the charge transfer band of Eu{sup 3+}. Thermogravimetric analysis and Raman spectroscopic study of Eu{sub 2}SiN{sub 3} revealed that oxidation of this compound in dry air takes place via a nitrogen retention complex. - Graphical abstract: Energy level scheme of Eu{sub 2}SiN{sub 3} showing the occupied N{sup 3−} 2p band (blue rectangle), unoccupied Eu{sup 2+} 5d band (white rectangle), occupied Eu{sup 2+} 4f ground states (filled red circles) and unoccupied Eu{sup 2+} ground states (open red circles). - Highlights: • Density functional theory calculations on the stability of M{sup 2+}L{sup 3+}SiN{sub 3} compounds. • Solid-state reaction synthesis of Eu{sub 2}SiN{sub 3}, CaLaSiN{sub 3}, EuLaSiN{sub 3} and CaEuSiN{sub 3}. • Determination of the Eu{sup 2+} 4f–5d and Eu{sup 3+} CT transitions in M{sup 2+}L{sup 3+}SiN{sub 3} compounds. • Oxidation of Eu{sub 2}SiN{sub 3} in dry air takes place via a nitrogen retention complex.

  4. Mixed-Valence Molecular Unit for Quantum Cellular Automata: Beyond the Born-Oppenheimer Paradigm through the Symmetry-Assisted Vibronic Approach.

    PubMed

    Clemente-Juan, Juan Modesto; Palii, Andrew; Coronado, Eugenio; Tsukerblat, Boris

    2016-08-01

    In this article, we focus on the electron-vibrational problem of the tetrameric mixed-valence (MV) complexes proposed for implementation as four-dot molecular quantum cellular automata (mQCA).1 Although the adiabatic approximation explored in ref 2 is an appropriate tool for the qualitative analysis of the basic characteristics of mQCA, like vibronic trapping of the electrons encoding binary information and cell-cell response, it loses its accuracy providing moderate vibronic coupling and fails in the description of the discrete pattern of the vibronic levels. Therefore, a precise solution of the quantum-mechanical vibronic problem is of primary importance for the evaluation of the shapes of the electron transfer optical absorption bands and quantitative analysis of the main parameters of tetrameric quantum cells. Here, we go beyond the Born-Oppenheimer paradigm and present a solution of the quantum-mechanical pseudo Jahn-Teller (JT) vibronic problem in bielectronic MV species (exemplified by the tetra-ruthenium complexes) based on the recently developed symmetry-assisted approach.3,4 The mathematical approach to the vibronic eigenproblem takes into consideration the point symmetry basis, and therefore, the total matrix of the JT Hamiltonian is blocked to the maximum extent. The submatrices correspond to the irreducible representations (irreps) of the point group. With this tool, we also extend the theory of the mQCA cell beyond the limit of prevailing Coulomb repulsion in the electronic pair (adopted in ref 2), and therefore, the general pseudo-JT problems for spin-singlet ((1)B1g, 2(1)A1g, (1)B2g, (1)Eu) ⊗ (b1g + eu) and spin-triplet states ((3)A2g, (3)B1g, 2(3)Eu) ⊗ (b1g + eu) in a square-planar bielectronic system are solved. The obtained symmetry-adapted electron-vibrational functions are employed for the calculation of the profiles (shape functions) of the charge transfer absorption bands in the tetrameric MV complexes and for the discussion of the

  5. EXAFS, XANES, and DFT study of the mixed-valence compound YMn2O5 : Site-selective substitution of Fe for Mn

    NASA Astrophysics Data System (ADS)

    Wunderlich, F.; Leisegang, T.; Weißbach, T.; Zschornak, M.; Stöcker, H.; Dshemuchadse, J.; Lubk, A.; Führlich, T.; Welter, E.; Souptel, D.; Gemming, S.; Seifert, G.; Meyer, D. C.

    2010-07-01

    In YMn2O5 , the Mn atoms occupy two nonequivalent Wyckoff sites within the unit cell exhibiting different oxygen coordinations, i.e., the system can be characterized as a mixed-valence compound. For the formation of the orthorhombic crystal structure, Jahn-Teller distortions are assumed to play an important role. In this study, we aimed at the investigation of the crystal structure changes upon the substitution of Mn by the non-Jahn-Teller cation Fe3+ . Therefore, we synthesized a series of YMn2-xFexO5 powder samples with x=0 , 0.5, and 1 by a citrate technique. We utilized extended x-ray absorption fine structure (EXAFS) and x-ray absorption near-edge structure (XANES) analysis as well as density-functional theory (DFT) to investigate the two nonequivalent Wyckoff sites within the orthorhombic crystal structure (confirmed for all compositions) occupied by transition-metal atoms. For quantitative determination of structural short-range order, all plausible options of substitution of Fe for Mn are discussed. On the basis of these evaluations, the EXAFS and XANES behavior is analyzed and appropriate crystallographic weights are assigned to the subset of structural models in accordance with the experimental data. From EXAFS analysis, using multiple-scattering theory, we conclude only the 4h Wyckoff site to be occupied by Fe [occupancy refined is (100±3)% in case of x=1 ]. Furthermore, taking the XANES spectra into account, we are able to verify the EXAFS results and additionally explain the differences in the MnK XANES spectra in dependence on x to be caused by changes in the dipole transitions to 4p final states. From quantitative pre-edge analysis an oxidation number of +4 for the Mn atom for x=1 is determined whereas the Fe valence is shown to be unchanged. Since the substitution process only involves one Wyckoff site, the experimentally observed limit to a maximum amount of x=1 is explained. Additionally, a possible disorder, discussed in the literature, is not

  6. Scaling properties for the first RE-like mixed valence examples in uranium compounds: U 2Ru 2Sn and U 2RuGa 8

    NASA Astrophysics Data System (ADS)

    Troć, Robert

    2006-05-01

    The present study was motivated by the scaling characterization of the first example of mixed valence (MV) RE-like behaviour found recently among intermetallic ternary uranium compounds. The χ( T) function for both title compounds has been fitted to the interconfigurational fluctuation (ICF) model of Sales and Wohlleben in order to determine the characteristic fluctuation temperatures Tsf and interconfigurational excitation energies Eex. A good scaling, with similar values of Tsf like from those derived from the ICF model, has been achieved for both these ternaries by plotting Tχ( T)/ C against the reduced T/ Tsf . Moreover, this scaling follows almost exactly those found earlier in a number of MV- RE compounds.

  7. A precision interferometric optical heterogeneity mapping system

    NASA Astrophysics Data System (ADS)

    Edgar, Gerard

    The object of this work was to design and build an instrument for mapping optical heterogeneities in fused silica blocks, with a sensitivity at least an order of magnitude better than any system currently available (prompted by a requirement of the Stanford Gravity Probe B project). The sources of inhomogeneities and the environment for containing these blocks to achieve measurements at this level are discussed with the implications for the instrument design. After a review of homogeneity testing methods, it was decided to develop an instrument system for use with several measurement methods. The most sensitive of these methods was selected to be fully developed in order to realise the measurement aim, the others being facilitated in the design. The design and development of a novel mechanically scanned heterodyne interferometric mapping system is described-following an error budget driven methodology. The critical 1mK thermally stable environment required for the liquid immersion measurement method employed, was exceeded by the design and development of a large computer controlled thermal enclosure to house the whole instrument system-sub-millidegree stabiliy achieved over periods of hours. Also described is the computer integration and software for execution and co-ordination of all measurements. The developed system meets the initial aim, being capable of an optical heterogeneity measurement sensitivity of 5 x 10-8 in refractive index in a 50mm thick sample. This was calibrated indirectly in a comparison with a Talystep surface profiling instrument. Further development work suggested could enhance this sensitivity by another factor of two.

  8. Structure and bonding in Yb4MgGe4: Yb2+/Yb3+ mixed-valency and charge separation.

    PubMed

    Tobash, Paul H; Bobev, Svilen

    2006-03-22

    Reported are the synthesis and the structural characterization of a new derivative of the RE5Tt4 family (RE = Rare-earth; Tt = Tetrel, = Si, Ge, i.e., group 14 element), Yb5-xMgxGe4 (x approximately 1). Crystal data for Yb4.04(1)Mg0.96(1)Ge4 at 23 degrees C: orthorhombic, space group Pnma (No. 62), Z = 4; a = 7.155(2) A, b = 14.769(5) A, c = 7.688(2) A; V = 812.5(4) A3. This phase is an example of a substitution of lanthanide metal (Yb) with a nonmagnetic element (Mg) within this structure type. Its structure can alternatively be described as an intergrowth of the hypothetical Yb2MgGe2, which features flat infinite [MgGe2]4- layers and the hypothetical YbGe with [Ge2]6- dimers. The flat [MgGe2]4- layers propagate in two dimensions (a and c), and they are offset by a distance of 1/4.a with respect to one another and are interspaced with layers of [Ge2]6- dimers and Yb cations filling the space between them. According to the structural and physical property data, Yb4MgGe4 is a heterogeneous mixed-valent compound, i.e. a system where one of the two symmetry-inequivalent Yb sites has atoms in closed-shell Yb2+ configuration, whereas the Yb3+ cations occupy a different crystallographic site.

  9. Optical properties of the prototype II-IV mixed-valence system Wolffram's red salt: a one mode treatment

    NASA Astrophysics Data System (ADS)

    Prassides, Kosmas; Schatz, Paul N.

    1991-03-01

    Focusing on a single unit cell, the coupled potential surfaces for the Pt II-Pt IV, Pt III-Pt III, Pt IV-Pt II configuration are described as a function of the Cl-Pt IV-Cl symmetry stretching coordinate. The vibronic Schrödinger equation is solved to find the nuclear motion over the three coupled surfaces. The resulting eigenvectors and eigenvalues are used to calculate the following: (i) the location of the intervalence band; (ii) the principal features of the well-known strong resonance Raman progression; (iii) the principal features of the luminescence band observed at about half the intervalence band energy. Quite good agreement with experiment is found for a reasonable set of parameters.

  10. The effect of pH and temperature on the reaction of fully reduced and mixed-valence cytochrome c oxidase with dioxygen.

    PubMed

    Oliveberg, M; Brzezinski, P; Malmström, B G

    1989-12-01

    The reaction of fully reduced and mixed-valence cytochrome oxidase with O2 has been followed in flow-flash experiments, starting from the CO complexes, at 428, 445, 605 and 830 nm between pH 5.8b and 9.0 in the temperature range of 2-40 degrees C. With the fully reduced enzyme, four kinetic phase with rate constants at pH 7.4 and 25 degrees C of 9 x 10(4), 2.5 x 10(4), 1.0 x 10(4) and 800 s(-1), respectively, are observed. The rates of the three last phases display a very small temperature dependence, corresponding to activation energies in the range 13-54 kJ x mol(-1). The rates of the third and fourth phases decrease at high pH due to the deprotonation of groups with pKa values of 8.3 and 8.8, respectively, but also the second phase appears to have a small pH dependence. In the reaction of the mixed-valence enzyme, three kinetic phases with rate constants at pH 7.4 and 25 degrees C of 9 x 10(4), 6000 and 150 s(-1), respectively, are observed. The third phase only has a small temperature dependence, corresponding to an activation energy of 20 kJ x mol(-1). No pH dependence could be detected for any phase. Reaction schemes consistent with the experimental observations are presented. The pH dependencies of the rates of the two final phase in the reaction of the fully reduced enzyme are proposed to be related to the involvement of protons in the reduction of a peroxide intermediate. The temperature dependence data suggest that the reorganization energies and driving forces are closely matched in all electron transfer steps with both enzyme forms. It is suggested that the slowest step in the reaction of the mixed-valence enzyme is a conformation change involved in the reaction cycle of cytochrome oxidase as a proton pump.

  11. Nonlinear lattice relaxation of photogenerated charge-transfer excitation in halogen-bridged mixed-valence metal complexes. II. Polaron channel

    NASA Astrophysics Data System (ADS)

    Mishima, A.; Nasu, K.

    1989-03-01

    The one-dimensional extended Peierls-Hubbard model with half-filled-band electrons is studied in order to clarify the lattice relaxation path of the photogenerated charge-transfer excitation in halogen-bridged mixed-valence metal complexes. The ground and excited states are calculated within mean-field theory for electrons and the adiabatic approximation for phonons. It is concluded that the main origin of the photoinduced absorption is a distant pair of the hole-polaron and the electron-polaron. This distant pair is created not from the ground state of the self-trapped exciton (STE), but from the excited states of the STE through their autodissociation. This is consistent with the experiment on the excitation energy dependence of the photoinduced absorption yield.

  12. C-H⋯Cl relevant discrepancy on structure, magnetic and electronic conductivity of two mixed-valence Cu ICu II coordination polymers

    NASA Astrophysics Data System (ADS)

    Shi, Ling; Yang, Ping; Huang, Guang; Li, Qian; Wang, Ning; Wu, Jian-Zhong; Yu, Ying

    2011-07-01

    Two mixed-valence Cu ICu II coordination polymers [Cu ICu II(qdiol)ClL] n (qdiol 2-=2,3-dioxyquinoxalinate, L=2,2'-bipyridine, 1; L=1,10-phenanthroline, 2) were obtained in basic ethanolic solution of CuCl 2, 1,4-dihydro-2,3-quinoxalinedione and L under the solvothermal condition. 1 and 2 are similar in composition, but differ remarkably in structure. The coordination modes of Cu II, qdiol 2- and L are identical in both complexes. But the Cu I ions are two- and three-coordinated, and the Cl - ions are terminal and bridging, in 1 and 2, respectively, which are relevant to the significantly different C-H⋯Cl hydrogen bonding pattern of bpy and phen. The temperature variable magnetic susceptibilities show that 1 is paramagnetic and 2 is weakly antiferromagnetic. The complex impedance spectroscopic studies indicate that both 1 and 2 are semiconductors and 2 is more conducting.

  13. Mixed-valence copper(I,II) complexes with 4-(1H-pyrazol-1-yl)-6-R-pyrimidines: from ionic structures to coordination polymers.

    PubMed

    Vinogradova, Katerina A; Krivopalov, Viktor P; Nikolaenkova, Elena B; Pervukhina, Natalia V; Naumov, Dmitrii Yu; Boguslavsky, Evgenii G; Bushuev, Mark B

    2016-01-14

    Two pyrimidine-based ligands, 4-(3,5-diphenyl-1H-pyrazol-1-yl)-6-(morpholino)pyrimidine () and 4-(3,5-diphenyl-1H-pyrazol-1-yl)-6-phenoxypyrimidine (), and a series of mixed-valence copper(i,ii) halide complexes, [Cu(L(2))2Br]2[Cu2Br4] (), [Cu(L(2))2Cl][CuCl2] (), and [Cu2L(3)Br3]n (), have been synthesized. The complex [Cu(L(2))2Br]2[Cu2Br4] was prepared by the reaction of with CuBr2 in a 1 : 1 molar ratio in MeCN. Its chlorido-analogue, the complex [Cu(L(2))2Cl][CuCl2], was synthesized by the reaction between , CuCl2 and CuCl in a 2 : 1 : 1 molar ratio in MeCN. The ligand acts as a chelating one. In the structures of the complexes [Cu(L(2))2Br]2[Cu2Br4] and [Cu(L(2))2Cl][CuCl2] the Cu(2+) ion is in the cationic part of the complex whereas the Cu(+) ion is located in the anionic part. The best way to synthesize the mixed-valence 1D coordination polymer [Cu2L(3)Br3]n is to react CuBr2 with in a 2 : 1 molar ratio in the MeCN/CHCl3 mixture on heating. In the structure of [Cu2L(3)Br3]n the ligand shows chelating/bridging tridentate coordination. This is the first example of the tridentate coordination of 4-(1H-pyrazol-1-yl)-6-R-pyrimidines. The striking difference between the coordination behavior of and (chelating bidentate vs. chelating/bridging coordination) is related with the possibility of rotation of the 6-phenoxy group around the C-O bond which makes the N(1) pyrimidine atom less sterically hindered, enabling it to participate in metal ion binding. Importantly, all copper ions in [Cu2L(3)Br3]n show similar tetrahedral environments, CuNBr3 and CuN2Br2, which is extremely rare for mixed-valence copper(i,ii) compounds. The ligands and show blue emission which is quenched upon their coordination to copper ions. The 1D coordination polymer [Cu2L(3)Br3]n shows high thermal stability and unusual solvent-occlusion properties. The role of the substituents favoring the formation of the mixed-valence copper(i,ii) complexes with 4-(1H-pyrazol-1-yl)-6-R

  14. Whole-Visible-Light Absorption of a Mixed-Valence Silver Vanadate Semiconductor Stemming from an Assistant Effect of d-d Transition.

    PubMed

    Dong, Hongjun; Chen, Gang; Sun, Jingxue; Li, Chunmei; Hu, Yidong; Han, Zhonghui

    2015-12-21

    Wide-light absorption is important to semiconductors exploited in many applications such as photocatalysts, photovoltaic devices, and light-emitting diodes, which can effectively improve solar energy utilization. Especially for photocatalysts, the development and design of new semiconductors that harvest the whole-visible-light region (λ = 400-800 nm) is rarely reported, which is still a tremendous challenge up to now. Here we realize whole-visible-light absorption up to 900 nm for a semiconductor by means of construction of a mixed-valence Ag0.68V2O5, which results from an assistant effect of d-d transition. Ag0.68V2O5 serving as a photocatalyst obviously exhibits photoelectrochemical and photocatalytic properties. Our results provide a brand-new feasible design strategy to broaden the light absorption of semiconductors and highlight a route to further make the best use of the full solar spectrum.

  15. {sup 35}Mn ESE-ENDOR of a mixed valence Mn(III)Mn(IV) complex: Comparison with the Mn cluster of the photosynthetic oxygen-evolving complex

    SciTech Connect

    Randall, D.W.; Sturgeon, B.E.; Ball, J.A.; Lorigan, G.A.; Chan, M.K.; Britt, R.D.; Klein, M.P. |; Armstrong, W.H.

    1995-11-29

    Analysis of {sup 55}Mn electron spin echo-electron nuclear double resonance (ESE-ENDOR) spectra obtained on a dinuclear mixed valence Mn(III)Mn(IV) complex [di-{mu}-oxotetrakis(2, 2`-bipyridine)dimanganese(III,IV)] (1) reveals the hyperfine and nuclear quadrupolar parameters for the spin I=5/2 {sup 55}Mn nucleus of both Mn(III) and Mn(IV) ions. The {sup 55}Mn ESE-ENDOR data obtained on the g = 2 Mn multiline EPR signal of the S{sub 2} state of the photosystem II oxygen-evolving complex demonstrate that this EPR signal cannot arise from a dinuclear Mn(III)-Mn(IV) center. The ENDOR spectra are consistent with a tetranuclear Mn cluster origin for the photosystem II multiline EPR signal. 75 refs., 7 figs., 2 tabs.

  16. Mixed valence and metamagnetism in a metal flux grown compound Eu{sub 2}Pt{sub 3}Si{sub 5}

    SciTech Connect

    Sarkar, Sumanta; Subbarao, Udumula; Joseph, Boby; Peter, Sebastian C.

    2015-05-15

    A new compound Eu{sub 2}Pt{sub 3}Si{sub 5} with plate shaped morphology has been grown from excess In flux. The compound crystallizes in the orthorhombic U{sub 2}Co{sub 3}Si{sub 5} structure type, Ibam space group and the lattice parameters are a=10.007(2) Å, b=11.666(2) Å and c=6.0011(12) Å. The crystal structure of this compound can be conceived as inter-twinned chains of [Pt{sub 2}Si{sub 2}] and [PtSi{sub 3}] tetrahedra connected along [100] direction to give rise to a complex three dimensional [Pt{sub 3}Si{sub 5}] network. Temperature dependent magnetic susceptibility data suggests that Eu{sub 2}Pt{sub 3}Si{sub 5} undergoes a strong antiferromagnetic ordering (T{sub N}=19 K) followed by a weak ferromagnetic transition (T{sub C}=5.5 K). The effective magnetic moment/Eu obtained from susceptibility data is 6.78 μ{sub B} accounts mixed valent Eu with almost 85% divalent Eu, which is supported by X-ray absorption near edge spectroscopy. The compound undergoes a metamagnetic transition under applied magnetic field through a probable spin flop mechanism. - Graphical abstract: Eu{sub 2}Pt{sub 3}Si{sub 5}, a new member in the U{sub 2}Co{sub 3}Si{sub 5} (Ibam) family undergoes metamagnetic transition at high magnetic field and Eu is in mixed valence state. - Highlights: • A new compound Eu{sub 2}Pt{sub 3}Si{sub 5} has been synthesized using indium as an inactive metal flux. • The compound undergoes metamagnetic transition at higher field. • Eu in this compound resides in a mixed valence state.

  17. C-H...Cl relevant discrepancy on structure, magnetic and electronic conductivity of two mixed-valence Cu{sup I}Cu{sup II} coordination polymers

    SciTech Connect

    Shi Ling; Yang Ping; Huang Guang; Li Qian; Wang Ning; Wu Jianzhong; Yu Ying

    2011-07-15

    Two mixed-valence Cu{sup I}Cu{sup II} coordination polymers [Cu{sup I}Cu{sup II}(qdiol)ClL]{sub n} (qdiol{sup 2-}=2,3-dioxyquinoxalinate, L=2,2'-bipyridine, 1; L=1,10-phenanthroline, 2) were obtained in basic ethanolic solution of CuCl{sub 2}, 1,4-dihydro-2,3-quinoxalinedione and L under the solvothermal condition. 1 and 2 are similar in composition, but differ remarkably in structure. The coordination modes of Cu{sup II}, qdiol{sup 2-} and L are identical in both complexes. But the Cu{sup I} ions are two- and three-coordinated, and the Cl{sup -} ions are terminal and bridging, in 1 and 2, respectively, which are relevant to the significantly different C-H...Cl hydrogen bonding pattern of bpy and phen. The temperature variable magnetic susceptibilities show that 1 is paramagnetic and 2 is weakly antiferromagnetic. The complex impedance spectroscopic studies indicate that both 1 and 2 are semiconductors and 2 is more conducting. - Graphical Abstract: Subtly different C-H...Cl bonding nature leads to diverse coordination modes and supramolecular networks, as well as physical properties of two Cu{sup I}Cu{sup II} coordination polymers with similar compositions. Highlights: > Two new Cu(I)-Cu(II) mixed-valence coordination polymers are obtained. > Environments of Cu(I) and Cl are different caused by C-H...Cl H-bonding. > Supramolecular networks are hence diverse. > Magnetic and semiconducting properties are influenced by the structures.

  18. Kinetic modelling of heterogeneous catalytic systems

    NASA Astrophysics Data System (ADS)

    Stamatakis, Michail

    2015-01-01

    The importance of heterogeneous catalysis in modern life is evidenced by the fact that numerous products and technologies routinely used nowadays involve catalysts in their synthesis or function. The discovery of catalytic materials is, however, a non-trivial procedure, requiring tedious trial-and-error experimentation. First-principles-based kinetic modelling methods have recently emerged as a promising way to understand catalytic function and aid in materials discovery. In particular, kinetic Monte Carlo (KMC) simulation is increasingly becoming more popular, as it can integrate several sources of complexity encountered in catalytic systems, and has already been used to successfully unravel the underlying physics of several systems of interest. After a short discussion of the different scales involved in catalysis, we summarize the theory behind KMC simulation, and present the latest KMC computational implementations in the field. Early achievements that transformed the way we think about catalysts are subsequently reviewed in connection to latest studies of realistic systems, in an attempt to highlight how the field has evolved over the last few decades. Present challenges and future directions and opportunities in computational catalysis are finally discussed.

  19. Crystal structure of RbAl 2Tb 4F 22: a second example of mixed-valence fluoroterbate with a random distribution of Tb 3+ and Tb 4+ ions

    NASA Astrophysics Data System (ADS)

    Josse, Michaël; Dubois, Marc; El-Ghozzi, Malika; Avignant, Daniel

    2005-01-01

    A new mixed-valence (III/IV) terbium fluoride RbAl 2Tb 4F 22 was obtained by direct fluorination of the stoichiometric mixture 1 RbCl + 2 AlF 3 + 4 TbF 4 at 650 °C under pure fluorine gas flow. The structure of RbAl 2Tb 4F 22 has been determined from single-crystal X-ray diffraction data and refined to a conventional R=0.020(R=0.023) from 676 independent reflections (29 parameters). This compound crystallizes in the tetragonal system, space group I4/mmm (No. 139) with a=10.662(2) Å and c=6.911(3) Å, Z=2. The structure is built of chains of edge-sharing TbF 8 dodecahedra surrounding the Tb 3+ and Tb 4+ ions randomly distributed over a unique crystallographic site. These chains arranged in a tetragonal packing are further held together by sharing vertices to form the three-dimensional framework which encompasses two kinds of channels parallel to the c tetragonal axis. The first ones accommodate the Rb + ions in 8-coordination. The second ones are occupied by isolated zigzag chains of trans-corner-sharing [AlF 6] 3- octahedra linked to four Tb chains by sharing equatorial fluorines. A structural relationship between RbAl 2Tb 4F 22 and BaY 2F 8 has been established.

  20. Localized and mixed valence state of Ce 4 f in superconducting and ferromagnetic CeO1 -xFxBiS2 revealed by x-ray absorption and photoemission spectroscopy

    NASA Astrophysics Data System (ADS)

    Sugimoto, T.; Ootsuki, D.; Paris, E.; Iadecola, A.; Salome, M.; Schwier, E. F.; Iwasawa, H.; Shimada, K.; Asano, T.; Higashinaka, R.; Matsuda, T. D.; Aoki, Y.; Saini, N. L.; Mizokawa, T.

    2016-08-01

    We have performed Ce L3-edge x-ray absorption spectroscopy (XAS) and Ce 4 d -4 f resonant photoemission spectroscopy (PES) on single crystals of CeO1 -xFxBiS2 for x =0.0 and 0.5 in order to investigate the Ce 4 f electronic states. In Ce L3-edge XAS, a mixed valence of Ce was found in the x =0.0 sample, and F doping suppressed it, which is consistent with the results on polycrystalline samples. As for resonant PES, we found that the Ce 4 f electrons in both x =0.0 and 0.5 systems respectively formed a flat band at 1.0 and 1.4 eV below the Fermi level and there was no contribution to the Fermi surfaces. Interestingly, Ce valence in CeOBiS2 deviates from Ce3 + even though Ce 4 f electrons are localized, indicating the Ce valence is not in a typical valence fluctuation regime. We assume that localized Ce 4 f in CeOBiS2 is mixed with unoccupied Bi 6 pz , which is consistent with a previous local structural study. Based on the analysis of the Ce L3-edge XAS spectra using Anderson's impurity model calculation, we found that the transfer integral becomes smaller, increasing the number of Ce 4 f electrons upon the F substitution for O.

  1. Novel Co(III)/Co(II) mixed valence compound [Co(bapen)Br2]2[CoBr4] (bapen = N,N‧-bis(3-aminopropyl)ethane-1,2-diamine): Synthesis, crystal structure and magnetic properties

    NASA Astrophysics Data System (ADS)

    Smolko, Lukáš; Černák, Juraj; Kuchár, Juraj; Miklovič, Jozef; Boča, Roman

    2016-09-01

    Green crystals of Co(III)/Co(II) mixed valence compound [Co(bapen)Br2]2[CoBr4] (bapen = N,N‧-bis(3-aminopropyl)ethane-1,2-diamine) were isolated from the aqueous system CoBr2 - bapen - HBr, crystallographically studied and characterized by elemental analysis and IR spectroscopy. Its ionic crystal structure is built up of [Co(bapen)Br2]+ cations and [CoBr4]2- anions. The Co(III) central atoms within the complex cations are hexacoordinated (donor set trans-N4Br2) with bromido ligands placed in the axial positions. The Co(II) atoms exhibit distorted tetrahedral coordination. Beside ionic forces weak Nsbnd H⋯Br intermolecular hydrogen bonding interactions contribute to the stability of the structure. Temperature variable magnetic measurements confirm the S = 3/2 behavior with the zero-field splitting of an intermediate strength: D/hc = 8.7 cm-1.

  2. Adaptable formations utilizing heterogeneous unmanned systems

    NASA Astrophysics Data System (ADS)

    Barnes, Laura E.; Garcia, Richard; Fields, MaryAnne; Valavanis, Kimon

    2009-05-01

    This paper addresses the problem of controlling and coordinating heterogeneous unmanned systems required to move as a group while maintaining formation. We propose a strategy to coordinate groups of unmanned ground vehicles (UGVs) with one or more unmanned aerial vehicles (UAVs). UAVs can be utilized in one of two ways: (1) as alpha robots to guide the UGVs; and (2) as beta robots to surround the UGVs and adapt accordingly. In the first approach, the UAV guides a swarm of UGVs controlling their overall formation. In the second approach, the UGVs guide the UAVs controlling their formation. The unmanned systems are brought into a formation utilizing artificial potential fields generated from normal and sigmoid functions. These functions control the overall swarm geometry. Nonlinear limiting functions are defined to provide tighter swarm control by modifying and adjusting a set of control variables forcing the swarm to behave according to set constraints. Formations derived are subsets of elliptical curves but can be generalized to any curvilinear shape. Both approaches are demonstrated in simulation and experimentally. To demonstrate the second approach in simulation, a swarm of forty UAVs is utilized in a convoy protection mission. As a convoy of UGVs travels, UAVs dynamically and intelligently adapt their formation in order to protect the convoy of vehicles as it moves. Experimental results are presented to demonstrate the approach using a fully autonomous group of three UGVs and a single UAV helicopter for coordination.

  3. Versatile Reactivity and Theoretical Evaluation of Mono- and Dinuclear Oxidovanadium(V) Compounds of Aroylazines: Electrogeneration of Mixed-Valence Divanadium(IV,V) Complexes.

    PubMed

    Dash, Subhashree P; Roy, Satabdi; Mohanty, Monalisa; Carvalho, M Fernanda N N; Kuznetsov, Maxim L; Pessoa, João Costa; Kumar, Amit; Patil, Yogesh P; Crochet, Aurélien; Dinda, Rupam

    2016-09-01

    The substituted hydrazones H2L(1-4) (L(1-4) = dibasic tridentate ONO(2-) donor ligands) obtained by the condensation of 2-hydroxy-1-naphthaldehyde and 2-aminobenzoylhydrazine (H2hnal-abhz) (H2L(1)) , 2-hydroxy-1-naphthaldehyde and 2-hydroxybenzoylhydrazine (H2hnal-hbhz) (H2L(2)), 2-hydroxy-1-acetonaphthone and benzoylhydrazine (H2han-bhz) (H2L(3)), or 2-hydroxy-1-acetonaphthone and 2-aminobenzoylhydrazine (H2han-abhz) (H2L(4)) are prepared and characterized. Reaction of ammonium vanadate with the appropriate H2L(1-4) results in the formation of oxidoethoxidovanadium(V) [V(V)O(OEt)(L(1-4))] (1-4) complexes. All compounds are characterized in the solid state and in solution by spectroscopic techniques (IR, UV-vis, (1)H, (13)C, and (51)V NMR, and electrospray ionization mass spectrometry). Single-crystal X-ray diffraction analysis of 1, 3, and 4 confirms the coordination of the corresponding ligands in the dianionic (ONO(2-)) enolate tautomeric form. In solution, the structurally characterized [V(V)O(OEt)(L)] compounds transform into the monooxido-bridged divanadium(V,V) [(V(V)OL)2-μ-O] complexes, with the processes being studied by IR and (1)H, (13)C, and (51)V NMR. The density functional theory (DFT) calculated Gibbs free energy of reaction 2[V(V)O(OEt)(L(4))] + H2O ⇆ [(V(V)OL(4))2-μ-O] + 2EtOH is only 2-3 kcal mol(-1), indicating that the dinuclear complexes may form in a significant amount. The electrochemical behavior of the complexes is investigated by cyclic voltammetry, with the V(V)-V(IV) E1/2(red) values being in the range 0.27-0.44 V (vs SCE). Upon controlled potential electrolysis, the corresponding (L)(O)V(IV)-O-V(V)(O)(L) mixed-valence species are obtained upon partial reduction of the [(V(V)OL)2-μ-O] complexes formed in solution, and some spectroscopic characteristics of these dinuclear mixed-valence complexes are investigated using DFT calculations and by electron paramagnetic resonance (EPR), with the formation of V(IV)-O-V(V) species being

  4. Versatile Reactivity and Theoretical Evaluation of Mono- and Dinuclear Oxidovanadium(V) Compounds of Aroylazines: Electrogeneration of Mixed-Valence Divanadium(IV,V) Complexes.

    PubMed

    Dash, Subhashree P; Roy, Satabdi; Mohanty, Monalisa; Carvalho, M Fernanda N N; Kuznetsov, Maxim L; Pessoa, João Costa; Kumar, Amit; Patil, Yogesh P; Crochet, Aurélien; Dinda, Rupam

    2016-09-01

    The substituted hydrazones H2L(1-4) (L(1-4) = dibasic tridentate ONO(2-) donor ligands) obtained by the condensation of 2-hydroxy-1-naphthaldehyde and 2-aminobenzoylhydrazine (H2hnal-abhz) (H2L(1)) , 2-hydroxy-1-naphthaldehyde and 2-hydroxybenzoylhydrazine (H2hnal-hbhz) (H2L(2)), 2-hydroxy-1-acetonaphthone and benzoylhydrazine (H2han-bhz) (H2L(3)), or 2-hydroxy-1-acetonaphthone and 2-aminobenzoylhydrazine (H2han-abhz) (H2L(4)) are prepared and characterized. Reaction of ammonium vanadate with the appropriate H2L(1-4) results in the formation of oxidoethoxidovanadium(V) [V(V)O(OEt)(L(1-4))] (1-4) complexes. All compounds are characterized in the solid state and in solution by spectroscopic techniques (IR, UV-vis, (1)H, (13)C, and (51)V NMR, and electrospray ionization mass spectrometry). Single-crystal X-ray diffraction analysis of 1, 3, and 4 confirms the coordination of the corresponding ligands in the dianionic (ONO(2-)) enolate tautomeric form. In solution, the structurally characterized [V(V)O(OEt)(L)] compounds transform into the monooxido-bridged divanadium(V,V) [(V(V)OL)2-μ-O] complexes, with the processes being studied by IR and (1)H, (13)C, and (51)V NMR. The density functional theory (DFT) calculated Gibbs free energy of reaction 2[V(V)O(OEt)(L(4))] + H2O ⇆ [(V(V)OL(4))2-μ-O] + 2EtOH is only 2-3 kcal mol(-1), indicating that the dinuclear complexes may form in a significant amount. The electrochemical behavior of the complexes is investigated by cyclic voltammetry, with the V(V)-V(IV) E1/2(red) values being in the range 0.27-0.44 V (vs SCE). Upon controlled potential electrolysis, the corresponding (L)(O)V(IV)-O-V(V)(O)(L) mixed-valence species are obtained upon partial reduction of the [(V(V)OL)2-μ-O] complexes formed in solution, and some spectroscopic characteristics of these dinuclear mixed-valence complexes are investigated using DFT calculations and by electron paramagnetic resonance (EPR), with the formation of V(IV)-O-V(V) species being

  5. Doubly end-on azido bridged mixed-valence cobalt trinuclear complex: Spectral study, VTM, inhibitory effect and antimycobacterial activity on human carcinoma and tuberculosis cells

    NASA Astrophysics Data System (ADS)

    Datta, Amitabha; Das, Kuheli; Sen, Chandana; Karan, Nirmal Kumar; Huang, Jui-Hsien; Lin, Chia-Her; Garribba, Eugenio; Sinha, Chittaranjan; Askun, Tulin; Celikboyun, Pinar; Mane, Sandeep B.

    2015-09-01

    Doubly end-on azido-bridged mixed-valence trinuclear cobalt complex, [Co3(L)2(N3)6(CH3OH)2] (1) is afforded by employing a potential monoanionic tetradentate-N2O2 Schiff base precursor (2-[{[2-(dimethylamino)ethyl]imino}methyl]-6-methoxyphenol; HL). Single crystal X-ray structure reveals that in 1, the adjacent CoII and CoIII ions are linked by double end-on azido bridges and thus the full molecule is generated by the site symmetry of a crystallographic twofold rotation axis. Complex 1 is subjected on different spectral analysis such as IR, UV-vis, emission and EPR spectroscopy. On variable temperature magnetic study, we observe that during cooling, the χMT values decrease smoothly until 15 K and then reaches to the value 1.56 cm3 K mol-1 at 2 K. Complex 1 inhibits the cell growth on human lung carcinoma (A549 cells), human colorectal (COLO 205 and HT-29 cells), and human heptacellular (PLC5 cells) carcinoma cells. Complex 1 exhibits anti-mycobacterial activity and considerable efficacy on Mycobacterium tuberculosis H37Rv ATCC 27294 and H37Ra ATCC 25177 strains.

  6. Charge-spin-orbital fluctuations in mixed valence spinels: Comparative study of AlV2O4 and LiV2O4

    NASA Astrophysics Data System (ADS)

    Uehara, Amane; Shinaoka, Hiroshi; Motome, Yukitoshi

    2015-11-01

    Mixed valence spinels provide a fertile playground for the interplay between charge, spin, and orbital degrees of freedom in strongly correlated electrons on a geometrically frustrated lattice. Among them, AlV2O4 and LiV2O4 exhibit contrasting and puzzling behavior: self-organization of seven-site clusters and heavy fermion behavior. We theoretically perform a comparative study of charge-spin-orbital fluctuations in these two compounds, on the basis of the multiband Hubbard models constructed by using the maximally localized Wannier functions obtained from the ab initio band calculations. Performing the eigenmode analysis of the generalized susceptibility, we find that, in AlV2O4 , the relevant fluctuation appears in the charge sector in σ -bonding type orbitals. In contrast, in LiV2O4 , optical-type spin fluctuations in the a1 g orbital are enhanced at an incommensurate wave number at low temperature. Implications from the comparative study are discussed for the contrasting behavior, including the metal-insulator transition under pressure in LiV2O4 .

  7. X-Ray Diffraction and Mössbauer Spectroscopy Studies of Pressure-Induced Phase Transitions in a Mixed-Valence Trinuclear Iron Complex.

    PubMed

    Madsen, Solveig R; Gunnlaugsson, Haraldur P; Moggach, Stephen A; Eikeland, Espen; Wu, Lai-Chin; Leupold, Olaf; Overgaard, Jacob; Iversen, Bo B

    2016-07-01

    The mixed-valence complex Fe3 O(cyanoacetate)6 (H2 O)3 (1) has been studied by single-crystal X-ray diffraction analysis at pressures up to 5.3(1) GPa and by (synchrotron) Mössbauer spectroscopy at pressures up to 8(1) GPa. Crystal structure refinements were possible up to 4.0(1) GPa. In this pressure range, 1 undergoes two pressure-induced phase transitions. The first phase transition at around 3 GPa is isosymmetric and involves a 60° rotation of 50 % of the cyanoacetate ligands. The second phase transition at around 4 GPa reduces the symmetry from rhombohedral to triclinic. Mössbauer spectra show that the complex becomes partially valence-trapped after the second phase transition. This sluggish pressure-induced valence-trapping is in contrast to the very abrupt valence-trapping observed when compound 1 is cooled from 130 to 120 K at ambient pressure. PMID:27245642

  8. Synthesis of (Ca,Ce3+,Ce4+)2Ti2O7: a pyrochlore with mixed-valence cerium

    NASA Astrophysics Data System (ADS)

    Garvie, Laurence A. J.; Xu, Huifang; Wang, Yifeng; Putnam, Robert L.

    2005-05-01

    Pyrochlore with mixed-valence Ce was synthesized by firing and annealing Ce(NO3)4, TiO2, and Ca(OH)2 with a stoichiometry of CaCeTi2O7 at 1300 °C. The product contains Ce-pyrochlore, Ce-rich perovskite, CeO2 (cerianite), and minor CaO. Electron energy-loss spectroscopy (EELS) revealed both Ce4+ and Ce3+ in the Ce-pyrochlore with a Ce4+ to total Ce (Ce4+/ΣCe) of 0.80 giving (CaCe0.213+Ce0.864+)TiO. Cerium in the perovskite and cerianite is dominated by Ce3+ and Ce4+, respectively. High-resolution transmission electron microscope (HRTEM) images show that the boundary between Ce-pyrochlore and Ce-rich perovskite is semi-coherently bonded. The orientational relationship between the neighboring Ce-pyrochlore and Ce-rich perovskite is not random. Ce-pyrochlore (CaCeTi2O7) is a chemical analogue for CaPuTi2O7, which is a proposed ceramic waste form for deposition of excess weapons-usable Pu in geological repositories. It is postulated, based on the presence of Ce3+ in the Ce-pyrochlore, that neutron poisons such as Gd can be incorporated into the CaPuTi2O7 phase.

  9. Mixed-valence metal oxide nanoparticles as electrochemical half-cells: substituting the Ag/AgCl of reference electrodes by CeO(2-x) nanoparticles.

    PubMed

    Nagarale, Rajaram K; Hoss, Udo; Heller, Adam

    2012-12-26

    Cations of mixed valence at surfaces of metal oxide nanoparticles constitute electrochemical half-cells, with potentials intermediate between those of the dissolved cations and those in the solid. When only cations at surfaces of the particles are electrochemically active, the ratio of electrochemically active/all cations is ~0.1 for 15 nm diameter CeO(2-x) particles. CeO(2-x) nanoparticle-loaded hydrogel films on printed carbon and on sputtered gold constitute reference electrodes having a redox potential similar to that of Ag/AgCl in physiological (0.14 M) saline solutions. In vitro the characteristics of potentially subcutaneously implantable glucose monitoring sensors made with CeO(2-x) nanoparticle reference electrodes are undistinguishable from those of sensors made with Ag/AgCl reference electrodes. Cerium is 900 times more abundant than silver, and commercially produced CeO(2-x) nanoparticle solutions are available at prices well below those of the Ag/AgCl pastes used in the annual manufacture of ~10(9) reference electrodes of glucose monitoring strips for diabetes management. PMID:23171288

  10. Modeling vaccination in a heterogeneous metapopulation system

    NASA Astrophysics Data System (ADS)

    Lachiany, Menachem

    2016-09-01

    We present here a multicity SIS epidemic model with vaccination. The model describes the dynamics of heterogeneous metapopulations that contain imperfectly vaccinated individuals. The effect of vaccination on heterogeneous multicity models has not been previously studied. We show that under very generic conditions, the epidemic threshold does not depend on the diffusion coefficient of the vaccinated individuals, but it does depend on the diffusion coefficient of the infected population. We then show, using a novel methodology, that the reproduction number is determined by the homogeneous model parameters and by the maximal number of neighbors a city can have, when the diffusion coefficient of the infected population is low. Finally, we present numerical simulations to support the analytical results.

  11. Mixed valence Mn(II)/Mn(III) [3 x 3] grid complexes: structural, electrochemical, spectroscopic, and magnetic properties.

    PubMed

    Thompson, Laurence K; Kelly, Timothy L; Dawe, Louise N; Grove, Hilde; Lemaire, Martin T; Howard, Judith A K; Spencer, Elinor C; Matthews, Craig J; Onions, Stuart T; Coles, Simon J; Horton, Peter N; Hursthouse, Michael B; Light, Mark E

    2004-11-29

    Mn(II)9 grid complexes with a [Mn9(mu-O)12] core, obtained by self-assembly of a series of tritopic picolinic dihydrazone ligands with Mn(II) salts, have been oxidized by both chemical and electrochemical methods to produce mixed oxidation state systems. Examples involving [Mn(III)3Mn(II)6] and [Mn(III)4Mn(II)5] combinations have been produced. Structures are reported for [Mn9(2poap-2H)6](NO3)6.14H2O (1), [Mn9(2poap-2H)6](ClO4)10.10H2O (3), and [Mn9(Cl2poap-2H)6](ClO4)9.14H2O.3CH3CN (10). Structural studies show distinct contraction of the corner grid sites on oxidation, with overall magnetic properties consistent with the resulting changes in electron distribution. Antiferromagnetic exchange in the outer ring of eight metal centers creates a ferrimagnetic subunit, which undergoes antiferromagnetic coupling to the central metal, leading to S=1/2 (3) and S2/2 (10) ground states. Two moderately intense absorptions are observed on oxidation of the Mn(II) grids in the visible and near-infrared (1000 nm, 700 nm), associated with charge transfer transitions (LMCT, IVCT respectively). Compound 1 crystallized in the monoclinic system, space group P2 1/n, with a=21.308(2) A, b=23.611(2) A, c=32.178(3) A, beta=93.820(2) degrees . Compound 3 crystallized in the tetragonal system, space group I, with a=b=18.44410(10) A, c = 24.9935(3) A. Compound 10 crystallized in the triclinic system, space group P, with a=19.1150(10) A, b=19.7221(10) A, c=26.8334(14) A, alpha=74.7190(10) degrees, beta=77.6970(10) degrees, gamma=64.7770(10) degrees. The facile oxidation of the Mn(II)9 grids is highlighted in terms of their potential use as molecular based platforms for switching and data storage. PMID:15554625

  12. Valence-delocalization of the mixed-valence oxo-centered trinuclear iron propionates [Fe{2/III}FeIIO(C2H5CO2)6(py)3] npy; n=0, 1.5

    NASA Astrophysics Data System (ADS)

    Nakamoto, Tadahiro; Katada, Motomi; Kawata, Satoshi; Kitagawa, Susumu; Sano, Hirotoshi; Konno, Michiko

    1994-12-01

    Mixed-valence trinuclear iron propionates [Fe{2/III}FeIIO(C2H5CO2)6(py)3]npy, where n=0, 1.5, were synthesized and the structure of the pyridine-solvated complex was determined by single-crystal X-ray diffraction. Mössbauer spectra of the solvated propionate complex showed a temperature-dependent mixed-valence state related to phase transitions, reaching an almost delocalized valence state at room temperature. On the other hand, the non-solvated propionate showed a remarkable change of the spectral shape related to a phase transition, remaining in a localized valence state at higher temperatures up to room temperature.

  13. Simulating Ru L3-edge X-ray Absorption Spectroscopy with Time-Dependent Density Functional Theory: Model Complexes and Electron Localization in Mixed-Valence Metal Dimers

    SciTech Connect

    Van Kuiken, Benjamin E.; Valiev, Marat; Daifuku, Stephanie L.; Bannan, Caitlin; Strader, Matthew L.; Cho, Hana; Huse, N.; Schoenlein, R. W.; Govind, Niranjan; Khalil, Munira

    2013-05-01

    Ruthenium L2,3-edge X-ray absorption (XA) spectroscopy probes transitions from core 2p orbitals to the 4d levels of the atom and is a powerful tool for interrogating the local electronic and molecular structure around the metal atom. However, a molecular-level interpretation of the Ru L2,3-edge spectral lineshapes is often complicated by spin–orbit coupling (SOC) and multiplet effects. In this study, we develop spin-free time-dependent density functional theory (TDDFT) as a viable and predictive tool to simulate the Ru L3-edge spectra. We successfully simulate and analyze the ground state Ru L3-edge XA spectra of a series of RuII and RuIII complexes: [Ru(NH3)6]2+/3+, [Ru(CN)6]4-/3-, [RuCl6]4-/3-, and the ground (1A1) and photoexcited (3MLCT) transient states of [Ru(bpy)3]2+ and Ru(dcbpy)2(NCS)2 (termed N3). The TDDFT simulations reproduce all the experimentally observed features in Ru L3-edge XA spectra. The advantage of using TDDFT to assign complicated Ru L3-edge spectra is illustrated by its ability to identify ligand specific charge transfer features in complex molecules. We conclude that the B3LYP functional is the most reliable functional for accurately predicting the location of charge transfer features in these spectra. Experimental and simulated Ru L3-edge XA spectra are presented for the transition metal mixed-valence dimers [(NC)5MII-CN-RuIII(NH3)5]- (where M = Fe or Ru) dissolved in water. We explore the spectral signatures of electron delocalization in Ru L3-edge XA spectroscopy and our simulations reveal that the inclusion of explicit solvent molecules is crucial for reproducing the experimentally determined valencies, highlighting the importance of the role of the solvent in transition metal charge transfer chemistry.

  14. [2.2]paracyclophane-bridged mixed-valence compounds: application of a generalized Mulliken-Hush three-level model.

    PubMed

    Amthor, Stephan; Lambert, Christoph

    2006-01-26

    A series of [2.2]paracylophane-bridged bis-triarylamine mixed-valence (MV) radical cations were analyzed by a generalized Mulliken-Hush (GMH) three-level model which takes two transitions into account: the intervalence charge transfer (IV-CT) band which is assigned to an optically induced hole transfer (HT) from one triarylamine unit to the second one and a second band associated with a triarylamine radical cation to bridge (in particular, the [2.2]paracyclophane bridge) hole transfer. From the GMH analysis, we conclude that the [2.2]paracyclophane moiety is not the limiting factor which governs the intramolecular charge transfer. AM1-CISD calculations reveal that both through-bond as well as through-space interactions of the [2.2]paracyclophane bridge play an important role for hole transfer processes. These electronic interactions are of course smaller than direct pi-conjugation, but from the order of magnitude of the couplings of the [2.2]paracyclophane MV species, we assume that this bridge is able to mediate significant through-space and through-bond interactions and that the cyclophane bridge acts more like an unsaturated spacer rather than a saturated one. From the exponential dependence of the electronic coupling V between the two triarylamine localized states on the distance r between the two redox centers, we infer that the hole transfer occurs via a superexchange mechanism. Our analysis reveals that even significantly longer pi-conjugated bridges should still mediate significant electronic interactions because the decay constant beta of a series of pi-conjugated MV species is small.

  15. CuFe O2 at a megabar: Stabilization of a mixed-valence low-spin magnetic semiconducting ground state

    NASA Astrophysics Data System (ADS)

    Xu, W. M.; Hearne, G. R.; Pasternak, M. P.

    2016-07-01

    The magnetic and electrical-transport properties of CuFe O2 have been studied by temperature-dependent 57Fe Mössbauer spectroscopy and resistance measurements to near megabar (˜100 GPa) pressures. Previous studies show that CuFe O2 comprises the following sublattices at P >23 GPa : 1/3[Cu(S=1 /2 ) 2 +Fe(S=2 ) 2 +O2 ] + 2/3[Cu(S=0 ) 1 +Fe(S=5 /2 ) 3 +O2 ] . The magnetic ordering temperatures of the sublattices, with both Fe valences in the high-spin state, reach a maximum at ˜50 GPa . At higher pressures two different magnetic components with collapsed magnetic hyperfine fields of 0 and ˜10 T have been detected by the Mössbauer probe. The pressure evolution and temperature dependence of the associated hyperfine interaction parameters to ˜95 GPa identifies these as low-spin Fe(S=0 ) 2 + and Fe(S=1 /2 ) 3 + states in the very-high-pressure phase of CuFe O2 . The F e3 + low-spin state exhibits an unusually high onset temperature for magnetic ordering, TM˜50 K . Resistance-temperature dependences show CuFe O2 in the low-spin state at very high pressure to be a narrow-gap semiconductor with variable range hopping of charge carriers. The derived Mott temperature from this conductivity mechanism, T0, undergoes an appreciable decrease from ˜50 GPa onwards where the spin-crossover regions nucleate and grow with increasing abundance in the lattice. An extrapolated T0 value of ˜105K at 100 GPa is interpreted as persistent charge carrier confinement in the low-spin phase. At these high densities a mixed-valence low-spin magnetic semiconducting ground state has been stabilized, in which strong electron correlations are persistent.

  16. Pseudotetragonal structure of Li(2+x)Ce(x)(3+)Ce(12-x)(4+)F(50): the first mixed valence cerium fluoride.

    PubMed

    Renaudin, Guillaume; Dieudonné, Belto; Avignant, Daniel; Mapemba, Elise; El-Ghozzi, Malika; Fleutot, Solène; Martinez, Hervé; Cerný, Radovan; Dubois, Marc

    2010-01-18

    The crystal structure of the new Li(5.5)Ce(12)F(50) compound has been fully characterized by single-crystal and synchrotron powder X-ray diffraction. An accurate pseudotetragonal structure was described in the monoclinic P2(1) space group with 68 independent crystallographic sites. The Li(5.5)Ce(12)F(50) composition belongs to the Li(2+x)Ce(x)(3+)Ce(12-x)(4+)F(50) solid solution. Its structure consists of an opened fluorine framework where a channel network allows the intercalation of relatively mobile lithium cations, inducing the formation of the mixed-valence cerium (the intercalation of Li(+) leads to the reduction of a part of Ce(4+) to Ce(3+)). One part of the lithium ions, necessary for the electroneutrality of the tetravalent equivalent cerium fluoride (Li(2)Ce(12)F(50) composition), is in a locked fluorine polyhedron. Only the supplementary x amount of lithium is able to be exchanged in Li(2+x)Ce(x)(3+)Ce(12-x)(4+)F(50). The structure of Li(2+x)Ce(x)(3+)Ce(12-x)(4+)F(50) is a rearrangement, due to lithium intercalation, of the base CeF(4) structure. Bond valence calculation on Ce sites, Ce coordination polyhedra volumes, and a calculated Ce cationic radius give the indication of a partial long-range ordering of trivalent and tetravalent cerium cations in specific slabs of the structure. (7)Li NMR spectroscopy and XPS analyses have confirmed all of the structure details.

  17. Solution study of a structurally characterized monoalkoxo-bound monooxo-vanadium(V) complex: spontaneous generation of the corresponding oxobridged divanadium(V,V) complex and its electroreduction to a mixed-valence species in solution.

    PubMed

    Dinda, Rupam; Sengupta, Parbati; Sutradhar, Manas; Mak, Thomas C W; Ghosh, Saktiprosad

    2008-07-01

    An interesting transformation of a structurally characterized monooxoalkoxovanadium(V) complex [VO(OEt)L] (LH 2 = a dibasic tridentate ONO donor ligand) in solution leading to the formation of the corresponding monooxobridged divanadium(V,V) complex (VOL) 2O is reported. This binuclear species in solution is adequately characterized by elemental analysis, measurement of conductance (in solution), various spectroscopic (UV-vis, IR, NMR, and mass spectrometry) techiniques and by cyclic voltammetry. The corresponding mixed-valence vanadium(IV,V) species has been generated in CH 3CN solution by controlled potential electrolysis of (VOL) 2O. This mixed-valence species is identified and studied by EPR technique (at room temperature and at liquid nitrogen temperature) and also by UV-vis spectroscopy. This study may be regarded as a general method of obtaining monooxo-bridged binuclear vanadium(V,V) species from the corresponding mononuclear monooxoalkoxovanadium(V) complexes of some selected dibasic tridentate ONO chelating ligands, which can be utilized as the precursor of monooxobridged divanadium(IV,V) mixed-valence species in solution obtainable by controlled potential electrolysis. PMID:18543908

  18. Admissible consensus for heterogeneous descriptor multi-agent systems

    NASA Astrophysics Data System (ADS)

    Yang, Xin-Rong; Liu, Guo-Ping

    2016-09-01

    This paper focuses on the admissible consensus problem for heterogeneous descriptor multi-agent systems. Based on algebra, graph and descriptor system theory, the necessary and sufficient conditions are proposed for heterogeneous descriptor multi-agent systems achieving admissible consensus. The provided conditions depend on not only the structure properties of each agent dynamics but also the topologies within the descriptor multi-agent systems. Moreover, an algorithm is given to design the novel consensus protocol. A numerical example demonstrates the effectiveness of the proposed design approach.

  19. Spatial snowdrift game of a heterogeneous agent system: cooperative behavior

    NASA Astrophysics Data System (ADS)

    Li, Ping-Ping; Ke, Jianhong; Jiang, Luo-Luo; Yuan, Xian-Zhang; Lin, Zhenquan

    2013-04-01

    We study the cooperative behavior of an evolutionary snowdrift game in a heterogeneous system with two types of agents, in which the inner-directed agents adopt the memory-based updating rule while the copycat-like ones take the unconditional imitation rule. The equilibrium cooperation frequency in such a heterogeneous system shows plateau structures with discontinuous steplike jumps as a function of the cost-to-benefit ratio, as well in homogeneous systems only with inner-directed agents [W.-X. Wang, J. Ren, G.R. Chen, B.-H. Wang, Phys. Rev. E 74, 056113 (2006)] or copycat-like ones [P.-P. Li, J. Ke, Z. Lin, P.M. Hui, Phys. Rev. E 85, 021111 (2012)]. One nontrivial feature for the heterogenous agent system is that the number of plateaux varies non-monotonically with the composition of the two mixing agents. Moreover, there exists a worst composition of the heterogeneous agents for each plateau, leading to the lowest cooperation level. We then qualitatively interpret these features by invoking the stability of local microscopic patterns. Our results are of some help in understanding the cooperative behaviors of heterogenous agent systems, and the qualitative analysis employed here also provides a useful method for studying in depth the evolutionary dynamics of spatial games.

  20. Activator-inhibitor systems on heterogeneous ecological networks

    NASA Astrophysics Data System (ADS)

    Nicolaides, C.; Cueto-Felgueroso, L.; Juanes, R.

    2012-12-01

    The consideration of activator-inhibitor systems as complex networks has broadened our knowledge of non-equilibrium reaction-diffusion processes in heterogeneous systems. For example, the Turing mechanism represents a classical model for the formation of self-organized spatial structures in non-equilibrium activator-inhibitor systems. The study of Turing patterns in networks with heterogeneous connectivity has revealed that, contrary to other models and systems, the segregation process takes place mainly in vertices of low degree. In this paper, we study the formation of vegetation patterns in semiarid ecosystems from the perspective of a heterogeneous interacting ecological network. The structure of ecological networks yields fundamental insight into the ecosystem self-organization. Using simple rules for the short-range activation and global inhibition, we reconstruct the observed power-law distribution of vegetation patch size that has been observed in semiarid ecosystems like the Kalahari transect.

  1. Principles of E-network modelling of heterogeneous systems

    NASA Astrophysics Data System (ADS)

    Tarakanov, D.; Tsapko, I.; Tsapko, S.; Buldygin, R.

    2016-04-01

    The present article is concerned with the analytical and simulation modelling of heterogeneous technical systems using E-network mathematical apparatus (the expansion of Petri nets). The distinguishing feature of the given system is the presence of the module6 which identifies the parameters of the controlled object as well as the external environment.

  2. A new partially deprotonated mixed-valence manganese(II,III) hydroxide-arsenate with electronic conductivity: magnetic properties of high- and room-temperature sarkinite.

    PubMed

    de Pedro, Imanol; Rojo, Jose M; Rius, Jordi; Vallcorba, Oriol; Ruiz de Larramendi, Idoia; Rodríguez Fernández, Jesús; Lezama, Luis; Rojo, Teofilo

    2012-05-01

    A new three-dimensional hydroxide-arsenate compound called compound 2 has been synthesized by heating (in air) of the sarkinite phase, Mn(2)(OH)AsO(4) (compound 1), with temperature and time control. The crystal structure of this high-temperature compound has been solved by Patterson-function direct methods. A relevant feature of this new material is that it is actually the first member of the adamite-type family with mixed-valence manganese(II,III) and electronic conductivity. Crystal data: a = 6.7367(5) Å, b = 7.5220(6) Å, c = 9.8117(6) Å, α = 92.410(4)°, β = 109.840(4)°, γ = 115.946(4)°, P1̅. The unit cell content derived from Rietveld refinement is Mn(8)(O(4)H(x))(AsO(4))(4). Its framework, projected along [111], is characterized by rings of eight Mn atoms with the OH(-)/O(2-) inside the rings. These rings form an almost perfect hexagonal arrangement with the AsO(4) groups placed in between. Bond-valence analysis indicates both partial deprotonation (x ≅ 3) and the presence of Mn in two different oxidation states (II and III), which is consistent with the electronic conductivity above 300 °C from electrochemical measurements. The electron paramagnetic resonance spectra of compound 1 and of its high-temperature form compound 2 show the presence of antiferromagnetic interactions with stronger magnetic coupling for the high-temperature phase. Magnetization measurements of room-temperature compound 1 show a complex magnetic behavior, with a three-dimensional antiferromagnetic ordering and magnetic anomalies at low temperatures, whereas for compound 2, an ordered state is not reached. Magnetostructural correlations indicate that superexchange interactions via oxygen are present in both compounds. The values of the magnetic exchange pathways [Mn-O-Mn] are characteristic of antiferromagnetic couplings. Notwithstanding, the existence of competition between different magnetic interactions through superexchange pathways can cause the complex magnetic

  3. Mixed-valence molecular four-dot unit for quantum cellular automata: Vibronic self-trapping and cell-cell response.

    PubMed

    Tsukerblat, Boris; Palii, Andrew; Clemente-Juan, Juan Modesto; Coronado, Eugenio

    2015-10-01

    Our interest in this article is prompted by the vibronic problem of charge polarized states in the four-dot molecular quantum cellular automata (mQCA), a paradigm for nanoelectronics, in which binary information is encoded in charge configuration of the mQCA cell. Here, we report the evaluation of the electronic levels and adiabatic potentials of mixed-valence (MV) tetra-ruthenium (2Ru(ii) + 2Ru(iii)) derivatives (assembled as two coupled Creutz-Taube complexes) for which molecular implementations of quantum cellular automata (QCA) was proposed. The cell based on this molecule includes two holes shared among four spinless sites and correspondingly we employ the model which takes into account the two relevant electron transfer processes (through the side and through the diagonal of the square) as well as the difference in Coulomb energies for different instant positions of localization of the hole pair. The combined Jahn-Teller (JT) and pseudo JT vibronic coupling is treated within the conventional Piepho-Krauzs-Schatz model adapted to a bi-electronic MV species with the square-planar topology. The adiabatic potentials are evaluated for the low lying Coulomb levels in which the antipodal sites are occupied, the case just actual for utilization in mQCA. The conditions for the vibronic self-trapping in spin-singlet and spin-triplet states are revealed in terms of the two actual transfer pathways parameters and the strength of the vibronic coupling. Spin related effects in degrees of the localization which are found for spin-singlet and spin-triplet states are discussed. The polarization of the cell is evaluated and we demonstrate how the partial delocalization caused by the joint action of the vibronic coupling and electron transfer processes influences polarization of a four-dot cell. The results obtained within the adiabatic approach are compared with those based on the numerical solution of the dynamic vibronic problem. Finally, the Coulomb interaction between

  4. Mixed-valence molecular four-dot unit for quantum cellular automata: Vibronic self-trapping and cell-cell response

    SciTech Connect

    Tsukerblat, Boris E-mail: andrew.palii@uv.es; Palii, Andrew E-mail: andrew.palii@uv.es; Clemente-Juan, Juan Modesto; Coronado, Eugenio

    2015-10-07

    Our interest in this article is prompted by the vibronic problem of charge polarized states in the four-dot molecular quantum cellular automata (mQCA), a paradigm for nanoelectronics, in which binary information is encoded in charge configuration of the mQCA cell. Here, we report the evaluation of the electronic levels and adiabatic potentials of mixed-valence (MV) tetra-ruthenium (2Ru(II) + 2Ru(III)) derivatives (assembled as two coupled Creutz-Taube complexes) for which molecular implementations of quantum cellular automata (QCA) was proposed. The cell based on this molecule includes two holes shared among four spinless sites and correspondingly we employ the model which takes into account the two relevant electron transfer processes (through the side and through the diagonal of the square) as well as the difference in Coulomb energies for different instant positions of localization of the hole pair. The combined Jahn-Teller (JT) and pseudo JT vibronic coupling is treated within the conventional Piepho-Krauzs-Schatz model adapted to a bi-electronic MV species with the square-planar topology. The adiabatic potentials are evaluated for the low lying Coulomb levels in which the antipodal sites are occupied, the case just actual for utilization in mQCA. The conditions for the vibronic self-trapping in spin-singlet and spin-triplet states are revealed in terms of the two actual transfer pathways parameters and the strength of the vibronic coupling. Spin related effects in degrees of the localization which are found for spin-singlet and spin-triplet states are discussed. The polarization of the cell is evaluated and we demonstrate how the partial delocalization caused by the joint action of the vibronic coupling and electron transfer processes influences polarization of a four-dot cell. The results obtained within the adiabatic approach are compared with those based on the numerical solution of the dynamic vibronic problem. Finally, the Coulomb interaction between

  5. Composition-induced structural, electrical, and magnetic phase transitions in AX-type mixed-valence cobalt oxynitride epitaxial thin films

    SciTech Connect

    Takahashi, Jumpei; Oka, Daichi; Hirose, Yasushi Yang, Chang; Fukumura, Tomoteru; Hasegawa, Tetsuya; Nakao, Shoichiro; Harayama, Isao; Sekiba, Daiichiro

    2015-12-07

    Synthesis of mid- to late-transition metal oxynitrides is generally difficult by conventional thermal ammonolysis because of thermal instability. In this letter, we synthesized epitaxial thin films of AX-type phase-pure cobalt oxynitrides (CoO{sub x}N{sub y}) by using nitrogen-plasma-assisted pulsed laser deposition and investigated their structural, electrical, and magnetic properties. The CoO{sub x}N{sub y} thin films with 0 ≤ y/(x + y) ≤ 0.63 grown on MgO (100) substrates showed a structural phase transition from rock salt (RS) to zinc blend at the nitrogen content y/(x + y) ∼ 0.5. As the nitrogen content increased, the room-temperature electrical resistivity of the CoO{sub x}N{sub y} thin films monotonically decreased from the order of 10{sup 5} Ω cm to 10{sup −4} Ω cm. Furthermore, we observed an insulator-to-metal transition at y/(x + y) ∼ 0.34 in the RS-CoO{sub x}N{sub y} phase, which has not yet been reported in Co{sup 2+}/Co{sup 3+} mixed-valence cobalt oxides with octahedral coordination. The low resistivity in the RS-CoO{sub x}N{sub y} phase, on the 10{sup −3} Ω cm order, may have originated from the intermediate spin state of Co{sup 3+} stabilized by the lowered crystal field symmetry of the CoO{sub 6−n}N{sub n} octahedra (n = 1, 2,…5). Magnetization measurements suggested that a magnetic phase transition occurred in the RS-CoO{sub x}N{sub y} films during the insulator-to-metal transition. These results demonstrate that low-temperature epitaxial growth is a promising approach for exploring novel electronic functionalities in oxynitrides.

  6. Synthesis, structure, and magnetic properties of a novel mixed-valence copper(I/II) phosphate, Cu{sub 2}PO{sub 4}

    SciTech Connect

    Etheredge, K.M.S.; Hwu, S.J.

    1995-09-27

    Via phase compatibility studies, a novel mixed-valence copper(I/II) phosphate, Cu{sub 2}PO{sub 4}, has been isolated from a direct reaction of Cu{sub 2}{sup I}O, Cu{sup II}O, and P{sub 2}O{sub 5} in fused silica. The single-crystal X-ray diffraction shows that the title compound crystallizes in a triclinic (P1) unit cell, with lattice dimensions a = 6.145(2) {angstrom}, b = 9.348(2) {angstrom}, c = 6.009(1) {angstrom}, {alpha} = 96.46(2){degrees}, {beta} = 100.16(2){degrees}, {gamma} = 73.97(2){degrees}, V = 325.8(1) {angstrom}{sup 3}; Z =4. The structure has been refined by the least-squares method to R = 0.019, R{sub w} = 0.030, and GOF = 1.43 for 128 variables. The four copper atoms in each asymmetric unit adopt three distorted coordination geometries that are consistent with the corresponding electronic states, e.g., square pyramidal Cu(1){sup II}O{sub 5}, octahedral Cu(2){sup II}O{sub 6}, and linear Cu(3,4){sup I}O{sub 2}. A low-dimensional framework exists consisting of arrays of nearly parallel CuO{sub 2} units which are separated by the nonmagnetic, closed-shell P{sup 5+} cation in PO{sub 4} tetrahedra. Closely spaced CuO{sub 2} chains and a relatively short Cu{sup I}-Cu{sup I} distance, e.g., 2.737 {angstrom} for Cu(3)-Cu(3), are attributed to the bond strength of the cross-linked PO{sub 4} tetrahedra. In the extended Cu(I/II)-O framework, short linkages of Cu{sup I}-O-Cu{sup II}-O-Cu{sup I} and Cu{sup II}-O-Cu{sup II}, composed of regular Cu-O bonds (1.86-1.99 {angstrom}), are interconnected through long Cu{sup II}-O bonds (2.36-2.74 {angstrom}). The magnetic measurements indicate that the Cu-O framework exhibits a spin 1/2 ground state and an antiferromagnetic ordering with a broad susceptibility maximum between 95 and 105 K. The results of stoichiometric synthesis, thermal analysis, and bond valence sum calculations of the title compound are also discussed.

  7. Mixed-valence molecular four-dot unit for quantum cellular automata: Vibronic self-trapping and cell-cell response

    NASA Astrophysics Data System (ADS)

    Tsukerblat, Boris; Palii, Andrew; Clemente-Juan, Juan Modesto; Coronado, Eugenio

    2015-10-01

    Our interest in this article is prompted by the vibronic problem of charge polarized states in the four-dot molecular quantum cellular automata (mQCA), a paradigm for nanoelectronics, in which binary information is encoded in charge configuration of the mQCA cell. Here, we report the evaluation of the electronic levels and adiabatic potentials of mixed-valence (MV) tetra-ruthenium (2Ru(ii) + 2Ru(iii)) derivatives (assembled as two coupled Creutz-Taube complexes) for which molecular implementations of quantum cellular automata (QCA) was proposed. The cell based on this molecule includes two holes shared among four spinless sites and correspondingly we employ the model which takes into account the two relevant electron transfer processes (through the side and through the diagonal of the square) as well as the difference in Coulomb energies for different instant positions of localization of the hole pair. The combined Jahn-Teller (JT) and pseudo JT vibronic coupling is treated within the conventional Piepho-Krauzs-Schatz model adapted to a bi-electronic MV species with the square-planar topology. The adiabatic potentials are evaluated for the low lying Coulomb levels in which the antipodal sites are occupied, the case just actual for utilization in mQCA. The conditions for the vibronic self-trapping in spin-singlet and spin-triplet states are revealed in terms of the two actual transfer pathways parameters and the strength of the vibronic coupling. Spin related effects in degrees of the localization which are found for spin-singlet and spin-triplet states are discussed. The polarization of the cell is evaluated and we demonstrate how the partial delocalization caused by the joint action of the vibronic coupling and electron transfer processes influences polarization of a four-dot cell. The results obtained within the adiabatic approach are compared with those based on the numerical solution of the dynamic vibronic problem. Finally, the Coulomb interaction between the

  8. Reward and aversion in a heterogeneous midbrain dopamine system.

    PubMed

    Lammel, Stephan; Lim, Byung Kook; Malenka, Robert C

    2014-01-01

    The ventral tegmental area (VTA) is a heterogeneous brain structure that serves a central role in motivation and reward processing. Abnormalities in the function of VTA dopamine (DA) neurons and the targets they influence are implicated in several prominent neuropsychiatric disorders including addiction and depression. Recent studies suggest that the midbrain DA system is composed of anatomically and functionally heterogeneous DA subpopulations with different axonal projections. These findings may explain a number of previously confusing observations that suggested a role for DA in processing both rewarding as well as aversive events. Here we will focus on recent advances in understanding the neural circuits mediating reward and aversion in the VTA and how stress as well as drugs of abuse, in particular cocaine, alter circuit function within a heterogeneous midbrain DA system. This article is part of a Special Issue entitled 'NIDA 40th Anniversary Issue'.

  9. Reward and aversion in a heterogeneous midbrain dopamine system

    PubMed Central

    Lammel, Stephan; Lim, Byung Kook; Malenka, Robert C.

    2013-01-01

    The ventral tegmental area (VTA) is a heterogeneous brain structure that serves a central role in motivation and reward processing. Abnormalities in the function of VTA dopamine (DA) neurons and the targets they influence are implicated in several prominent neuropsychiatric disorders including addiction and depression. Recent studies suggest that the midbrain DA system is composed of anatomically and functionally heterogeneous DA subpopulations with different axonal projections. These findings may explain a number of previously confusing observations that suggested a role for DA in processing both rewarding as well as aversive events. Here we will focus on recent advances in understanding the neural circuits mediating reward and aversion in the VTA and how stress as well as drugs of abuse, in particular cocaine, alter circuit function within a heterogeneous midbrain DA system. PMID:23578393

  10. Toward photochemistry of integrated heterogeneous systems

    SciTech Connect

    Matsumoto, Yoshiyasu

    2012-09-07

    This paper begins with describing the excitation mechanisms in surface photochemistry and nuclear dynamics of adsorbate induced by electronic excitation. An illustrative example is Cs adsorbate on a Cu(111) surface. This adsorption system shows drastic changes in the electronic structure with coverage; this allows us to examine different types of electronic excitations that stimulate nuclear motions of Cs. Remarks are made on challenges in photoinduced processes at well-defined surfaces: direct observations of adsorbate-substrate vibrational modes and photoinduced reactions between adsorbates. Then, the paper addresses some issues in more complex systems: metal-liquid interfaces and powdered photocatalysts of metal oxides. Photochemistry and photoinduced nuclear dynamics at metal-liquid interfaces have not been well explored. Studies on this subject may make it possible to bridge the gap between surface photochemistry and electrochemistry. Photocatalysis with powdered catalysts has been extensively studied and is still an active area, but our understanding of the mechanism of photocatalysis is far from satisfactory. Although complicated, the highly integrated systems provide an opportunity to extend our knowledge of surface photochemistry.

  11. Development of a heterogeneous laminating resin system

    NASA Technical Reports Server (NTRS)

    Biermann, T. F.; Hopper, L. C.

    1985-01-01

    The factors which effect the impact resistance of laminating resin systems and yet retain equivalent performance with the conventional 450 K curing epoxy matrix systems in other areas were studied. Formulation work was conducted on two systems, an all-epoxy and an epoxy/bismaleimide, to gain fundamental information on the effect formulation changes have upon neat resin and composite properties. The all-epoxy work involved formulations with various amounts and combinations of eight different epoxy resins, four different hardeners, fifteen different toughening agents, a filler, and a catalyst. The epoxy/bismaleimide effort improved formulations with various amounts and combinations of nine different resins, four different hardeners, eight different toughening agents, four different catalysts, and a filler. When a formulation appeared to offer the proper combination of properties required for a laminating resin Celion 3K-70P fabric was prepregged. Initial screening tests on composites primarily involved Gardner type impact and measurement of short beam shear strengths under dry and hot/wet conditions.

  12. Toward photochemistry of integrated heterogeneous systems

    NASA Astrophysics Data System (ADS)

    Matsumoto, Yoshiyasu

    2012-09-01

    This paper begins with describing the excitation mechanisms in surface photochemistry and nuclear dynamics of adsorbate induced by electronic excitation. An illustrative example is Cs adsorbate on a Cu(111) surface. This adsorption system shows drastic changes in the electronic structure with coverage; this allows us to examine different types of electronic excitations that stimulate nuclear motions of Cs. Remarks are made on challenges in photoinduced processes at well-defined surfaces: direct observations of adsorbate-substrate vibrational modes and photoinduced reactions between adsorbates. Then, the paper addresses some issues in more complex systems: metal-liquid interfaces and powdered photocatalysts of metal oxides. Photochemistry and photoinduced nuclear dynamics at metal-liquid interfaces have not been well explored. Studies on this subject may make it possible to bridge the gap between surface photochemistry and electrochemistry. Photocatalysis with powdered catalysts has been extensively studied and is still an active area, but our understanding of the mechanism of photocatalysis is far from satisfactory. Although complicated, the highly integrated systems provide an opportunity to extend our knowledge of surface photochemistry.

  13. Systemic risk and heterogeneous leverage in banking networks

    NASA Astrophysics Data System (ADS)

    Kuzubaş, Tolga Umut; Saltoğlu, Burak; Sever, Can

    2016-11-01

    This study probes systemic risk implications of leverage heterogeneity in banking networks. We show that the presence of heterogeneous leverages drastically changes the systemic effects of defaults and the nature of the contagion in interbank markets. Using financial leverage data from the US banking system, through simulations, we analyze the systemic significance of different types of borrowers, the evolution of the network, the consequences of interbank market size and the impact of market segmentation. Our study is related to the recent Basel III regulations on systemic risk and the treatment of the Global Systemically Important Banks (GSIBs). We also assess the extent to which the recent capital surcharges on GSIBs may curb financial fragility. We show the effectiveness of surcharge policy for the most-levered banks vis-a-vis uniform capital injection.

  14. Time Transient Effects in Heterogeneous Permselective Systems

    NASA Astrophysics Data System (ADS)

    Green, Yoav; Park, Sinwook; Yossifon, Gilad

    2015-03-01

    The passage of an electric current through a permselective medium (membranes/nanochannels) under an applied electric field is characterized by the formation of ionic concentration gradients which result in regions of depleted and enriched ionic concentration at opposite ends of the medium, i.e. concentration polarization (CP). In this work, we study the time-transient behavior of the concentration and electric potential distributions in a realistic two dimensional and three layered system (i.e. microchannel-permselective medium-microchannel device). We provide an analytical solution for the concentration under the simplifying assumptions of local-electroneutrality, ideal permselectivity and negligible convection while the electric potential is solved numerically. It is shown that time transient effects occur over the diffusive time scale until steady-state is achieved. The numerical steady state solution is compared with previous analytical results and good quantitative behavior is observed.

  15. Data and Network Science for Noisy Heterogeneous Systems

    ERIC Educational Resources Information Center

    Rider, Andrew Kent

    2013-01-01

    Data in many growing fields has an underlying network structure that can be taken advantage of. In this dissertation we apply data and network science to problems in the domains of systems biology and healthcare. Data challenges in these fields include noisy, heterogeneous data, and a lack of ground truth. The primary thesis of this work is that…

  16. Seismic wave propagation on heterogeneous systems with CHAPEL

    NASA Astrophysics Data System (ADS)

    Gokhberg, Alexey; Fichtner, Andreas

    2014-05-01

    Simulations of seismic wave propagation play a key role in the exploration of the Earth's internal structure, the prediction of earthquake-induced ground motion, and numerous other applications. In order to harness modern heterogeneous HPC systems, we implement a spectral-element discretization of the seismic wave equation using the emerging parallel programming language Chapel. High-performance massively parallel computing systems are widely used for solving seismological problems. A recent trend in the evolution of such systems is a transition from homogeneous architectures based on the conventional CPU to faster and more energy-efficient heterogeneous architectures that combine CPU with the special purpose GPU accelerators. These new heterogeneous architectures have much higher hardware complexity and are thus more difficult to program. Therefore transition to heterogeneous computing systems widens the well known gap between the performance of the new hardware and the programmers' productivity. In particular, programming heterogeneous systems typically involves a mix of various programming technologies like MPI, CUDA, or OpenACC. This conventional approach increases complexity of application code, limits its portability and reduces the programmers' productivity. We are approaching this problem by introducing a unified high-level programming model suitable for both conventional and hybrid architectures. Our model is based on the Partitioned Global Address Space (PGAS) paradigm used by several modern parallel programming languages. We implemented this model by extending Chapel, the emerging parallel programming language created at Cray Inc. In particular, we introduced the language abstractions for GPU-based domain mapping and extended the open source Chapel compiler (version 1.8.0) with facilities designed to translate Chapel high-level parallel programming constructs into CUDA kernels. We used this extended Chapel implementation to re-program the package for the

  17. Unprecedented structural variations in trinuclear mixed valence Co(II/III) complexes: theoretical studies, pnicogen bonding interactions and catecholase-like activities.

    PubMed

    Hazari, Alokesh; Kanta Das, Lakshmi; Kadam, Ramakant M; Bauzá, Antonio; Frontera, Antonio; Ghosh, Ashutosh

    2015-02-28

    Three new mixed valence trinuclear Co(II/III) compounds cis-[Co3L2(MeOH)2(N3)2(μ1,1-N3)2] (1), trans-[Co3L2(H2O)2(N3)2(μ1,1-N3)2]·(H2O)2 (2) and [Co3L(R)2(N3)3(μ1,3-N3)] (3) have been synthesized by reacting a di-Schiff base ligand (H2L) or its reduced form [H2LR] (where H2L= N,N'-bis(salicylidene)-1,3-propanediamine and H2LR= N,N'-bis(2-hydroxybenzyl)-1,3-propanediamine) with cobalt perchlorate hexahydrate and sodium azide. All three products have been characterized by IR, UV-Vis and EPR spectroscopies, ESI-MS, elemental, powder and single crystal X-ray diffraction analyses. Complex 2 is an angular trinuclear species in which two terminal octahedral Co(III)N2O4 centers coordinate to the central octahedral cobalt(II) ion through μ2-phenoxido oxygen and μ1,1-azido nitrogen atoms along with two mutually cis-oxygen atoms of methanol molecules. On the other hand, in linear trinuclear complex , in addition to the μ2-phenoxido and μ1,1-azido bridges with terminal octahedral Co(III) centres, the central Co(II) is bonded with two mutually trans-oxygen atoms of water molecules. Thus the cis-trans configuration of the central Co(II) is solvent dependent. In complex 3, the two terminal octahedral Co(III)N2O4 centers coordinate to the central penta-coordinated Co(II) ion through double phenoxido bridges along with the nitrogen atom of a terminal azido ligand. In addition, the two terminal Co(III) are connected through a μ1,3-azido bridge that participates in pnicogen bonding interactions (intermolecular N-N interaction) as an acceptor. Both the cis and trans isomeric forms of 1 and 2 have been optimized using density functional theory (DFT) calculations and it is found that the cis configuration is energetically more favorable than the trans one. However, the trans configuration of 2 is stabilized by the hydrogen bonding network involving a water dimer. The pnicogen bonding interactions have been demonstrated using MEP surfaces and CSD search which support the counter

  18. Heterogeneity and subjectivity in binary-state opinion formation systems

    NASA Astrophysics Data System (ADS)

    Guo, Long; Luo, Zhongjie; Zhu, Yueying

    2013-11-01

    In society, there is heterogeneous interaction and randomness in human decision making. In order to unfold the roles and the competition of the two factors mentioned above in opinion formation, we propose a toy model, which follows a majority rule with a Fermi function, on scale-free networks with degree exponent γ. The heterogeneous interaction is related to the connectivity of a person with the interactive parameter β, and the randomness of human decision making is quantified by the interaction noise T. We find that a system with heterogeneity of network topology and interaction shows robustness perturbed by the interaction noise T according to the theoretical analysis and numerical simulation. Then, when T → 0, the homogeneous interaction (β ≃ 0) has a powerful implication for the emergence of a consensus state. Furthermore, the emergence of the two extreme values shows the competition of the heterogeneity of interaction and the subjectivity of human decision making in opinion formation. Our present work provides some perspective on and tools for understanding the diversity of opinion in our society.

  19. Short-term synaptic plasticity and heterogeneity in neural systems

    NASA Astrophysics Data System (ADS)

    Mejias, J. F.; Kappen, H. J.; Longtin, A.; Torres, J. J.

    2013-01-01

    We review some recent results on neural dynamics and information processing which arise when considering several biophysical factors of interest, in particular, short-term synaptic plasticity and neural heterogeneity. The inclusion of short-term synaptic plasticity leads to enhanced long-term memory capacities, a higher robustness of memory to noise, and irregularity in the duration of the so-called up cortical states. On the other hand, considering some level of neural heterogeneity in neuron models allows neural systems to optimize information transmission in rate coding and temporal coding, two strategies commonly used by neurons to codify information in many brain areas. In all these studies, analytical approximations can be made to explain the underlying dynamics of these neural systems.

  20. Optimization of contaminant removal for heterogeneous systems by soil venting

    SciTech Connect

    Walton, J.C.; Casey, D.; Anker, C.; LeMone, D.

    1996-12-31

    The efficiency of remediation of vadose zone organic compounds can be enhanced by refinement of methods for soil venting and bioventing in complex heterogeneous systems. This can be accomplished by (a) identification of physical and chemical conditions (e.g., soil temperature, moisture content, flow rates) required for rapid contaminant removal rates, (b) precise engineering control of identified parameters in the subsurface, and (c) development of knowledge-based operational strategies providing greater removal efficiencies at low cost. One method with promise is to moderately heat and humidify the input/replacement air during venting. Initial calculations indicate that this strategy may be quite effective in enhancing remediation of heterogeneous systems with diffusional control of cleanup time.

  1. Sharing information and data across heterogeneous e-health systems.

    PubMed

    Ganguly, Sukanta; Kataria, Pavandeep; Juric, Radmila; Ertas, Atila; Tanik, Murat M

    2009-06-01

    Information and data sharing across heterogeneous e-health systems, focusing on the management of patient care, have become the backbone of modern delivery of sustainable telemedicine services. Information and data available to healthcare practitioners in such environments range from patient's medical records, stored in repositories at places where patients have been treated, to a variety of information related to medical research, pharmaceutical products, or information stored within social networks of healthcare interest groups. This study sought to demonstrate two different approaches enabling the sharing of information/data across heterogeneous e-health systems: (1) Context-Aware Data Retrieval Architecture (CADRA), which secures the extraction and presentation of e-health information to users in requested format, and (2) Generic Ontology for Context Aware, Interoperable, and Data Sharing (Go-CID) software applications, which secure semantic interoperation across heterogeneous e-health data sources. Proof-of-concept was demonstrated in both cases, CADRA and Go-CID, to achieve understanding and building of knowledge about e-health environments. This study invites practical solutions for interoperable e-health systems.

  2. Verification of heterogeneous multi-agent system using MCMAS

    NASA Astrophysics Data System (ADS)

    Choi, Jiyoung; Kim, Seungkeun; Tsourdos, Antonios

    2015-03-01

    The focus of the paper is how to model autonomous behaviours of heterogeneous multi-agent systems such that it can be verified that they will always operate within predefined mission requirements and constraints. This is done by using formal methods with an abstraction of the behaviours modelling and model checking for their verification. Three case studies are presented to verify the decision-making behaviours of heterogeneous multi-agent system using a convoy mission scenario. The multi-agent system in a case study has been extended by increasing the number of agents and function complexity gradually. For automatic verification, model checker for multi-agent systems (MCMAS) is adopted due to its novel capability to accommodate the multi-agent system and successfully verifies the targeting behaviours of the team-level autonomous systems. The verification results help retrospectively the design of decision-making algorithms improved by considering additional agents and behaviours during three steps of scenario modification. Consequently, the last scenario deals with the system composed of a ground control system, two unmanned aerial vehicles, and four unmanned ground vehicles with fault-tolerant and communication relay capabilities.

  3. Organ system heterogeneity DB: a database for the visualization of phenotypes at the organ system level

    PubMed Central

    Mannil, Deepthi; Vogt, Ingo; Prinz, Jeanette; Campillos, Monica

    2015-01-01

    Perturbations of mammalian organisms including diseases, drug treatments and gene perturbations in mice affect organ systems differently. Some perturbations impair relatively few organ systems while others lead to highly heterogeneous or systemic effects. Organ System Heterogeneity DB (http://mips.helmholtz-muenchen.de/Organ_System_Heterogeneity/) provides information on the phenotypic effects of 4865 human diseases, 1667 drugs and 5361 genetically modified mouse models on 26 different organ systems. Disease symptoms, drug side effects and mouse phenotypes are mapped to the System Organ Class (SOC) level of the Medical Dictionary of Regulatory Activities (MedDRA). Then, the organ system heterogeneity value, a measurement of the systemic impact of a perturbation, is calculated from the relative frequency of phenotypic features across all SOCs. For perturbations of interest, the database displays the distribution of phenotypic effects across organ systems along with the heterogeneity value and the distance between organ system distributions. In this way, it allows, in an easy and comprehensible fashion, the comparison of the phenotypic organ system distributions of diseases, drugs and their corresponding genetically modified mouse models of associated disease genes and drug targets. The Organ System Heterogeneity DB is thus a platform for the visualization and comparison of organ system level phenotypic effects of drugs, diseases and genes. PMID:25313158

  4. Streamlining the Release Process for the Heterogeneous Columbus Software System

    NASA Astrophysics Data System (ADS)

    Manthey, Temenushka; Brandt, Matthias; Westerholt, Uwe

    2013-08-01

    One of the challenges during the exploitation of complex and long-term space systems such as the Columbus Laboratory is to continuously improve the efficiency of the software maintenance process without compromising quality. All types of software maintenance, i.e. corrective, adaptive, perfective, and preventive have to be supported to keep the productivity of the system at a high level over a long period of time. Furthermore, the maintenance approach has to cope with a heterogeneous system composed of multiple software components which differ in terms of target platforms, programming languages, and build mechanisms. In this paper, we share our experience in streamlining the release process for the complex and heterogeneous Columbus Software System (CSS). We describe how the time-consuming software release process of CSS was made more efficient and controllable by adopting continuous delivery techniques. Finally, an assessment of the maturity level of the process four years ago compared with the present situation is presented to provide estimation for the achieved progress.

  5. STRUCTURELAB: a heterogeneous bioinformatics system for RNA structure analysis.

    PubMed

    Shapiro, B A; Kasprzak, W

    1996-08-01

    STRUCTURELAB is a computational system that has been developed to permit the use of a broad array of approaches for the analysis of the structure of RNA. The goal of the development is to provide a large set of tools that can be well integrated with experimental biology to aid in the process of the determination of the underlying structure of RNA sequences. The approach taken views the structure determination problem as one of dealing with a database of many computationally generated structures and provides the capability to analyze this data set from different perspectives. Many algorithms are integrated into one system that also utilizes a heterogeneous computing approach permitting the use of several computer architectures to help solve the posed problems. These different computational platforms make it relatively easy to incorporate currently existing programs as well as newly developed algorithms and to best match these algorithms to the appropriate hardware. The system has been written in Common Lisp running on SUN or SGI Unix workstations, and it utilizes a network of participating machines defined in reconfigurable tables. A window-based interface makes this heterogeneous environment as transparent to the user as possible. PMID:9076633

  6. Time-dependent ion transport in heterogeneous permselective systems

    NASA Astrophysics Data System (ADS)

    Green, Yoav; Yossifon, Gilad

    2015-06-01

    The current study extends previous analytical and numerical solutions of chronopotentiometric response of one-dimensional systems consisting of three layers to the more realistic two-dimensional (2D) heterogeneous ion-permselective medium. An analytical solution for the transient concentration-polarization problem, under the local electroneutrality approximation and assumption of ideal permselectivity, was obtained using the Laplace transform and separation of variables technique. Then the 2D electric potential was obtained numerically and was compared to the full Poisson-Nernst-Planck solution. It was then shown that the resultant voltage drop across the system varies between the initial Ohmic response and that of the steady state accounting for concentration polarization. Also, the field-focusing effect in a 2D system is shown to result in a faster depletion of ions at the permselective interface.

  7. Time-dependent ion transport in heterogeneous permselective systems.

    PubMed

    Green, Yoav; Yossifon, Gilad

    2015-06-01

    The current study extends previous analytical and numerical solutions of chronopotentiometric response of one-dimensional systems consisting of three layers to the more realistic two-dimensional (2D) heterogeneous ion-permselective medium. An analytical solution for the transient concentration-polarization problem, under the local electroneutrality approximation and assumption of ideal permselectivity, was obtained using the Laplace transform and separation of variables technique. Then the 2D electric potential was obtained numerically and was compared to the full Poisson-Nernst-Planck solution. It was then shown that the resultant voltage drop across the system varies between the initial Ohmic response and that of the steady state accounting for concentration polarization. Also, the field-focusing effect in a 2D system is shown to result in a faster depletion of ions at the permselective interface.

  8. Photoacoustic Signal Formation in Heterogeneous Multilayer Systems with Piezoelectric Detection

    NASA Astrophysics Data System (ADS)

    Isaiev, Mykola; Andrusenko, Dmytro; Tytarenko, Alona; Kuzmich, Andrey; Lysenko, Vladimir; Burbelo, Roman

    2014-12-01

    A new efficient model describing photoacoustic (PA) signal formation with piezoelectric detection is reported. Multilayer sandwich-like systems: heterogeneous studied structure—buffer layer—piezoelectric transducers are considered. In these systems, the buffer layer is used for spatial redistribution of thermoelastic force moments generated in the investigated structure. Thus, mechanical properties of this layer play a crucial role to ensure perfect control of the detected voltage formed on a piezoelectric transducer by contribution of different regions of the studied structure. In particular, formation of the voltage signal strongly depends on the point at which the thermoelastic source is applied. Therefore, use of relatively simple linear Green's functions introduced in frames of the Kirchhoff-Love theory is chosen as an efficient approach for the PA signal description. Moreover, excellent agreement between the theoretical model and measured results obtained on a heterogeneous "porous silicon-bulk Si substrate" structure is stated. Furthermore, resolving of the inverse problem with fitting of the experimental curves by the developed model allows reliable evaluation of the thermal conductivity of the nanostructured porous silicon layer.

  9. A uniform approach for programming distributed heterogeneous computing systems

    PubMed Central

    Grasso, Ivan; Pellegrini, Simone; Cosenza, Biagio; Fahringer, Thomas

    2014-01-01

    Large-scale compute clusters of heterogeneous nodes equipped with multi-core CPUs and GPUs are getting increasingly popular in the scientific community. However, such systems require a combination of different programming paradigms making application development very challenging. In this article we introduce libWater, a library-based extension of the OpenCL programming model that simplifies the development of heterogeneous distributed applications. libWater consists of a simple interface, which is a transparent abstraction of the underlying distributed architecture, offering advanced features such as inter-context and inter-node device synchronization. It provides a runtime system which tracks dependency information enforced by event synchronization to dynamically build a DAG of commands, on which we automatically apply two optimizations: collective communication pattern detection and device-host-device copy removal. We assess libWater’s performance in three compute clusters available from the Vienna Scientific Cluster, the Barcelona Supercomputing Center and the University of Innsbruck, demonstrating improved performance and scaling with different test applications and configurations. PMID:25844015

  10. Nanoscale magnetic stirring bars for heterogeneous catalysis in microscopic systems.

    PubMed

    Yang, Shuliang; Cao, Changyan; Sun, Yongbin; Huang, Peipei; Wei, Fangfang; Song, Weiguo

    2015-02-23

    Nanometer-sized magnetic stirring bars containing Pd nanoparticles (denoted as Fe3 O4 -NC-PZS-Pd) for heterogeneous catalysis in microscopic system were prepared through a facile two-step process. In the hydrogenation of styrene, Fe3 O4 -NC-PZS-Pd showed an activity similar to that of the commercial Pd/C catalyst, but much better stability. In microscopic catalytic systems, Fe3 O4 -NC-PZS-Pd can effectively stir the reaction solution within microdrops to accelerate mass transfer, and displays far better catalytic activity than the commercial Pd/C for the hydrogenation of methylene blue in an array of microdroplets. These results suggested that the Fe3 O4 -NC-PZS-Pd could be used as nanoscale stirring bars in nanoreactors.

  11. Heterogeneity in the lymphatic vascular system and its origin.

    PubMed

    Ulvmar, Maria H; Mäkinen, Taija

    2016-09-01

    Lymphatic vessels have historically been viewed as passive conduits for fluid and immune cells, but this perspective is increasingly being revised as new functions of lymphatic vessels are revealed. Emerging evidence shows that lymphatic endothelium takes an active part in immune regulation both by antigen presentation and expression of immunomodulatory genes. In addition, lymphatic vessels play an important role in uptake of dietary fat and clearance of cholesterol from peripheral tissues, and they have been implicated in obesity and arteriosclerosis. Lymphatic vessels within different organs and in different physiological and pathological processes show a remarkable plasticity and heterogeneity, reflecting their functional specialization. In addition, lymphatic endothelial cells (LECs) of different organs were recently shown to have alternative developmental origins, which may contribute to the development of the diverse lymphatic vessel and endothelial functions seen in the adult. Here, we discuss recent developments in the understanding of heterogeneity within the lymphatic system considering the organ-specific functional and molecular specialization of LECs and their developmental origin. PMID:27357637

  12. Heterogeneity in the lymphatic vascular system and its origin.

    PubMed

    Ulvmar, Maria H; Mäkinen, Taija

    2016-09-01

    Lymphatic vessels have historically been viewed as passive conduits for fluid and immune cells, but this perspective is increasingly being revised as new functions of lymphatic vessels are revealed. Emerging evidence shows that lymphatic endothelium takes an active part in immune regulation both by antigen presentation and expression of immunomodulatory genes. In addition, lymphatic vessels play an important role in uptake of dietary fat and clearance of cholesterol from peripheral tissues, and they have been implicated in obesity and arteriosclerosis. Lymphatic vessels within different organs and in different physiological and pathological processes show a remarkable plasticity and heterogeneity, reflecting their functional specialization. In addition, lymphatic endothelial cells (LECs) of different organs were recently shown to have alternative developmental origins, which may contribute to the development of the diverse lymphatic vessel and endothelial functions seen in the adult. Here, we discuss recent developments in the understanding of heterogeneity within the lymphatic system considering the organ-specific functional and molecular specialization of LECs and their developmental origin.

  13. Heterogeneity in the lymphatic vascular system and its origin

    PubMed Central

    Ulvmar, Maria H.; Mäkinen, Taija

    2016-01-01

    Lymphatic vessels have historically been viewed as passive conduits for fluid and immune cells, but this perspective is increasingly being revised as new functions of lymphatic vessels are revealed. Emerging evidence shows that lymphatic endothelium takes an active part in immune regulation both by antigen presentation and expression of immunomodulatory genes. In addition, lymphatic vessels play an important role in uptake of dietary fat and clearance of cholesterol from peripheral tissues, and they have been implicated in obesity and arteriosclerosis. Lymphatic vessels within different organs and in different physiological and pathological processes show a remarkable plasticity and heterogeneity, reflecting their functional specialization. In addition, lymphatic endothelial cells (LECs) of different organs were recently shown to have alternative developmental origins, which may contribute to the development of the diverse lymphatic vessel and endothelial functions seen in the adult. Here, we discuss recent developments in the understanding of heterogeneity within the lymphatic system considering the organ-specific functional and molecular specialization of LECs and their developmental origin. PMID:27357637

  14. A method for reliability estimation of heterogeneous systems

    NASA Astrophysics Data System (ADS)

    Mihalache, Alin; Guérin, Fabrice; Barreau, Mihaela; Todoskoff, Alexis; Bacivarov, Ioan; Bacivarov, Angelica

    2009-01-01

    Reliability estimation is becoming an important issue of the design process of complex heterogeneous systems. The concept of reliability is frequently seen as being one of the least controlled points and for some as being the critical point. Since these systems are very complex to study, the evaluation of their reliability is extremely difficult. In this paper, we propose a global method to estimate the mechatronic system reliability using operating field data. Since we have a small amount of data, we use an estimation method called Bayesian Restoration Maximization (BRM) method, thus increasing the estimation accuracy. The BRM method needs to define some prior knowledge. For this purpose, we propose to define the prior distribution using a Monte-Carlo simulation based on stochastic Petri Nets (SPN) model and on the operating field data. The stochastic PN model describes the functional and dysfunctional behaviours. In this study, we deal with the case of n repairable systems until a deterministic censoring time (for example, this censoring time may be the warranty period of an ABS system). We consider repair as the replacement of the failing component by an identical one in the case of electronic and mechanical subsystem and in the case of software, the default is rectified on all the subsystems. We simulate the failures times and we compute the confidence interval. The proposed method allows reliability evaluating both for n mechatronic systems and for their different subsystems.

  15. Biological optimization of heterogeneous dose distributions in systemic radiotherapy

    SciTech Connect

    Strigari, Lidia; D'Andrea, Marco; Maini, Carlo Ludovico; Sciuto, Rosa; Benassi, Marcello

    2006-06-15

    The standard computational method developed for internal radiation dosimetry is the MIRD (medical internal radiation dose) formalism, based on the assumption that tumor control is given by uniform dose and activity distributions. In modern systemic radiotherapy, however, the need for full 3D dose calculations that take into account the heterogeneous distribution of activity in the patient is now understood. When information on nonuniform distribution of activity becomes available from functional imaging, a more patient specific 3D dosimetry can be performed. Application of radiobiological models can be useful to correlate the calculated heterogeneous dose distributions to the current knowledge on tumor control probability of a homogeneous dose distribution. Our contribution to this field is the introduction of a parameter, the F factor, already used by our group in studying external beam radiotherapy treatments. This parameter allows one to write a simplified expression for tumor control probability (TCP) based on the standard linear quadratic (LQ) model and Poisson statistics. The LQ model was extended to include different treatment regimes involving source decay, incorporating the repair '{mu}' of sublethal radiation damage, the relative biological effectiveness and the effective 'waste' of dose delivered when repopulation occurs. The sensitivity of the F factor against radiobiological parameters ({alpha},{beta},{mu}) and the influence of the dose volume distribution was evaluated. Some test examples for {sup 131}I and {sup 90}Y labeled pharmaceuticals are described to further explain the properties of the F factor and its potential applications. To demonstrate dosimetric feasibility and advantages of the proposed F factor formalism in systemic radiotherapy, we have performed a retrospective planning study on selected patient case. F factor formalism helps to assess the total activity to be administered to the patient taking into account the heterogeneity in

  16. Full-waveform inversion on heterogeneous HPC systems

    NASA Astrophysics Data System (ADS)

    Gokhberg, Alexey; Fichtner, Andreas

    2016-04-01

    We present a spectral-element implementation of full seismic waveform inversion for large heterogeneous HPC systems. In this we address the optimal parallelisation configurations of individual simulations, the large I/O requirements of adjoint simulations, and the scheduling of large numbers of forward and adjoint solves, typical for realistic inversions. Using GPU accelerators allows us to achieve a 3.5-4 times performance improvement over the best known homogeneous implementation. We achieve GPU memory throughput varying from 60 to 80% of the peak bandwidth, thus providing good utilisation of hardware resources. We demonstrate the practical applicability of our developments in a real-data application in the western Mediterranean. With the help of GPU accelerators, we are able to model and invert seismic wave propagation in a frequency band that is broader than permitted by the use of CPUs alone, which helps bridging the traditional gap between crustal and mantle tomography.

  17. Itinerant Magnetism and its Characterization in Heterogeneous Systems

    NASA Astrophysics Data System (ADS)

    Victora, Randall Harry

    1985-12-01

    This thesis describes calculations for the magnetic and electronic properties of a variety of systems that display itinerant magnetism. An early chapter considers the exact solution of a Hubbard Hamiltonian within the context of periodic boundary conditions; remaining calculations treat various heterogeneous transition-metal systems by means of a realistic tight-binding scheme, with single site, full orbital interactions treated self consistently. The latter method is shown to be consistently reliable: In each case where comparison with experiment or with state-of-the-art calculations could be made, there is agreement in the integrated properties, such as spin polarization, to within a few percent. Comparison of calculated density of states with photoemission data, although complicated by various many-body processes, again shows excellent agreement. This relatively inexpensive computational method is used to calculate the properties of complex systems which are difficult or impossible to treat by first-principle methods, and to test for unusual configurations or symmetry breaking in simple systems. Important conclusions drawn from these calculations include: (1) The unusual shape of the Fe-Co curve on the Slater-Pauling plot, a subject of theoretical debate since the 1930s, is primarily caused by magnetic saturation in the Co-rich alloy and a weak electron-electron interaction in the Fe-rich alloy. The explanation of Pauling, i.e., only 2.4 magnetizable d electrons per spin, is an incomplete representation of the true reasons behind this anomalous Fe-Co curve. (2) A Co monolayer on a Cu(111) surface possesses a new kind of two-atom state which may be described as "spatially modulated". This state has a total energy only slightly above the ferromagnetic ground-state energy. (3) A Cr monolayer on the Fe (100) surface is ferromagnetic with a spin polarization of 3.63 electrons. This spin polarization is considerably larger than any other known transition-metal system

  18. Scaling of flow and transport behavior in heterogeneous groundwater systems

    NASA Astrophysics Data System (ADS)

    Scheibe, Timothy; Yabusaki, Steven

    1998-11-01

    Three-dimensional numerical simulations using a detailed synthetic hydraulic conductivity field developed from geological considerations provide insight into the scaling of subsurface flow and transport processes. Flow and advective transport in the highly resolved heterogeneous field were modeled using massively parallel computers, providing a realistic baseline for evaluation of the impacts of parameter scaling. Upscaling of hydraulic conductivity was performed at a variety of scales using a flexible power law averaging technique. A series of tests were performed to determine the effects of varying the scaling exponent on a number of metrics of flow and transport behavior. Flow and transport simulation on high-performance computers and three-dimensional scientific visualization combine to form a powerful tool for gaining insight into the behavior of complex heterogeneous systems. Many quantitative groundwater models utilize upscaled hydraulic conductivity parameters, either implicitly or explicitly. These parameters are designed to reproduce the bulk flow characteristics at the grid or field scale while not requiring detailed quantification of local-scale conductivity variations. An example from applied groundwater modeling is the common practice of calibrating grid-scale model hydraulic conductivity or transmissivity parameters so as to approximate observed hydraulic head and boundary flux values. Such parameterizations, perhaps with a bulk dispersivity imposed, are then sometimes used to predict transport of reactive or non-reactive solutes. However, this work demonstrates that those parameters that lead to the best upscaling for hydraulic conductivity and head do not necessarily correspond to the best upscaling for prediction of a variety of transport behaviors. This result reflects the fact that transport is strongly impacted by the existence and connectedness of extreme-valued hydraulic conductivities, in contrast to bulk flow which depends more strongly on

  19. Stochastic Analysis and Design of Heterogeneous Microstructural Materials System

    NASA Astrophysics Data System (ADS)

    Xu, Hongyi

    Advanced materials system refers to new materials that are comprised of multiple traditional constituents but complex microstructure morphologies, which lead to superior properties over the conventional materials. To accelerate the development of new advanced materials system, the objective of this dissertation is to develop a computational design framework and the associated techniques for design automation of microstructure materials systems, with an emphasis on addressing the uncertainties associated with the heterogeneity of microstructural materials. Five key research tasks are identified: design representation, design evaluation, design synthesis, material informatics and uncertainty quantification. Design representation of microstructure includes statistical characterization and stochastic reconstruction. This dissertation develops a new descriptor-based methodology, which characterizes 2D microstructures using descriptors of composition, dispersion and geometry. Statistics of 3D descriptors are predicted based on 2D information to enable 2D-to-3D reconstruction. An efficient sequential reconstruction algorithm is developed to reconstruct statistically equivalent random 3D digital microstructures. In design evaluation, a stochastic decomposition and reassembly strategy is developed to deal with the high computational costs and uncertainties induced by material heterogeneity. The properties of Representative Volume Elements (RVE) are predicted by stochastically reassembling SVE elements with stochastic properties into a coarse representation of the RVE. In design synthesis, a new descriptor-based design framework is developed, which integrates computational methods of microstructure characterization and reconstruction, sensitivity analysis, Design of Experiments (DOE), metamodeling and optimization the enable parametric optimization of the microstructure for achieving the desired material properties. Material informatics is studied to efficiently reduce the

  20. Dynamic resource allocation scheme for distributed heterogeneous computer systems

    NASA Technical Reports Server (NTRS)

    Liu, Howard T. (Inventor); Silvester, John A. (Inventor)

    1991-01-01

    This invention relates to a resource allocation in computer systems, and more particularly, to a method and associated apparatus for shortening response time and improving efficiency of a heterogeneous distributed networked computer system by reallocating the jobs queued up for busy nodes to idle, or less-busy nodes. In accordance with the algorithm (SIDA for short), the load-sharing is initiated by the server device in a manner such that extra overhead in not imposed on the system during heavily-loaded conditions. The algorithm employed in the present invention uses a dual-mode, server-initiated approach. Jobs are transferred from heavily burdened nodes (i.e., over a high threshold limit) to low burdened nodes at the initiation of the receiving node when: (1) a job finishes at a node which is burdened below a pre-established threshold level, or (2) a node is idle for a period of time as established by a wakeup timer at the node. The invention uses a combination of the local queue length and the local service rate ratio at each node as the workload indicator.

  1. The middleware architecture supports heterogeneous network systems for module-based personal robot system

    NASA Astrophysics Data System (ADS)

    Choo, Seongho; Li, Vitaly; Choi, Dong Hee; Jung, Gi Deck; Park, Hong Seong; Ryuh, Youngsun

    2005-12-01

    On developing the personal robot system presently, the internal architecture is every module those occupy separated functions are connected through heterogeneous network system. This module-based architecture supports specialization and division of labor at not only designing but also implementation, as an effect of this architecture, it can reduce developing times and costs for modules. Furthermore, because every module is connected among other modules through network systems, we can get easy integrations and synergy effect to apply advanced mutual functions by co-working some modules. In this architecture, one of the most important technologies is the network middleware that takes charge communications among each modules connected through heterogeneous networks systems. The network middleware acts as the human nerve system inside of personal robot system; it relays, transmits, and translates information appropriately between modules that are similar to human organizations. The network middleware supports various hardware platform, heterogeneous network systems (Ethernet, Wireless LAN, USB, IEEE 1394, CAN, CDMA-SMS, RS-232C). This paper discussed some mechanisms about our network middleware to intercommunication and routing among modules, methods for real-time data communication and fault-tolerant network service. There have designed and implemented a layered network middleware scheme, distributed routing management, network monitoring/notification technology on heterogeneous networks for these goals. The main theme is how to make routing information in our network middleware. Additionally, with this routing information table, we appended some features. Now we are designing, making a new version network middleware (we call 'OO M/W') that can support object-oriented operation, also are updating program sources itself for object-oriented architecture. It is lighter, faster, and can support more operation systems and heterogeneous network systems, but other general

  2. Spatial heterogeneity of mesopredator release within an oceanic island system.

    PubMed

    Rayner, Matt J; Hauber, Mark E; Imber, Michael J; Stamp, Rosalie K; Clout, Mick N

    2007-12-26

    Predator-prey communities are ubiquitous in ecology, but introduced predators can drive native species to extinction within island systems, prompting the eradication of such exotics. Ecological theory predicts that elimination of top-introduced predators from islands can lead to the counterintuitive decline of native prey populations through the ecological release of smaller introduced species in a process termed "mesopredator release." We show, in accordance with mesopredator release theory and counter to conservation goals for a New Zealand island reserve, that initial eradication of cats on Little Barrier Island led to reduced breeding success of Cook's petrels, which also are vulnerable to predation by a mesopredator, the Pacific rat. The rat's impact on prey productivity varied with elevation within the island. Rat eradication was followed by a rise in petrel productivity, in support of both ecological theory and practical conservation management goals. It appears that interactions among introduced predators, native prey, and environmental gradients can drive counterintuitive and spatially heterogeneous responses to predator eradications from islands. Location-specific, ecosystem-level understanding is essential for predicting the outcomes of such restoration management techniques. PMID:18083843

  3. Introduction of Sap ERP System Into a Heterogeneous Academic Community

    NASA Astrophysics Data System (ADS)

    Mornar, Vedran; Fertalj, Krešimir; Kalpić, Damir

    2010-06-01

    Introduction of a complex ERP system like SAP into a heterogeneous academic environment like the University of Zagreb is far from being a trivial task. The University comprises more than 30 constituents, called faculties or academies, geographically dispersed, with long and specific traditions. Financing according to the lump sum principle, enforced in Croatia as a side effect of the in Europe obligatory and omnipresent Bologna process, requires a unified view on the educational institutions in order to provide a more just and appropriate financing scheme than the current one. After the experience with own development to support educational tasks and student administration, for standard financial and administration tasks SAP has been chosen as the most appropriate platform. The developer was selected after public bidding and the authors' institution was chosen for the pilot project. The authors were playing principal roles in the process of successful deployment and still expect to offer their expertise for implementation in the rest of the University. However, serious risks stemming from lack of motivation by some constituents are present.

  4. Spatial heterogeneity of mesopredator release within an oceanic island system

    PubMed Central

    Rayner, Matt J.; Hauber, Mark E.; Imber, Michael J.; Stamp, Rosalie K.; Clout, Mick N.

    2007-01-01

    Predator–prey communities are ubiquitous in ecology, but introduced predators can drive native species to extinction within island systems, prompting the eradication of such exotics. Ecological theory predicts that elimination of top-introduced predators from islands can lead to the counterintuitive decline of native prey populations through the ecological release of smaller introduced species in a process termed “mesopredator release.” We show, in accordance with mesopredator release theory and counter to conservation goals for a New Zealand island reserve, that initial eradication of cats on Little Barrier Island led to reduced breeding success of Cook's petrels, which also are vulnerable to predation by a mesopredator, the Pacific rat. The rat's impact on prey productivity varied with elevation within the island. Rat eradication was followed by a rise in petrel productivity, in support of both ecological theory and practical conservation management goals. It appears that interactions among introduced predators, native prey, and environmental gradients can drive counterintuitive and spatially heterogeneous responses to predator eradications from islands. Location-specific, ecosystem-level understanding is essential for predicting the outcomes of such restoration management techniques. PMID:18083843

  5. Development of an Intelligent Monitoring and Control System for a Heterogeneous Numerical Propulsion System Simulation

    NASA Technical Reports Server (NTRS)

    Reed, John A.; Afjeh, Abdollah A.; Lewandowski, Henry; Homer, Patrick T.; Schlichting, Richard D.

    1996-01-01

    The NASA Numerical Propulsion System Simulation (NPSS) project is exploring the use of computer simulation to facilitate the design of new jet engines. Several key issues raised in this research are being examined in an NPSS-related research project: zooming, monitoring and control, and support for heterogeneity. The design of a simulation executive that addresses each of these issues is described. In this work, the strategy of zooming, which allows codes that model at different levels of fidelity to be integrated within a single simulation, is applied to the fan component of a turbofan propulsion system. A prototype monitoring and control system has been designed for this simulation to support experimentation with expert system techniques for active control of the simulation. An interconnection system provides a transparent means of connecting the heterogeneous systems that comprise the prototype.

  6. Calculation of antibody affinity in homogeneous and heterogeneous systems.

    PubMed

    Chalquest, R R

    1988-12-01

    Antibody affinity is an important determinant of all antibody-antigen reactions. A new computer program, AFCRV, was developed to calculate binding constants with data from a radioimmunoassay on most microcomputers in the laboratory by using constant-ratio dilution curves. Evaluation of a homogeneous or heterogeneous antibody in the presence of a single antigen can be accomplished.

  7. Crystallogenesis of Mixed-Valence Fe-Serpentines: Implications for Their Formation during the Aqueous Alteration of Carbonaceous Chondrites' Parent Body

    NASA Astrophysics Data System (ADS)

    Caste, F.; Elmaleh, A.; Abdelmoula, M.; Menguy, N.; Ona-Nguema, G.; Gérard, M.

    2014-12-01

    (Fe3+,Fe2+)-bearing serpentines close to the ideal endmember cronstedtite (Fe2+2,Fe3+) (Si, Fe3+) O5 (OH)4, are major components of CM2-type carbonaceous chondrites. Along with other hydrated minerals, they mostly formed during the first million years of the Solar System by aqueous alteration on the meteorite parent body. These secondary minerals could provide constraints to the processes of alteration. Here we developed a two-step protocol (room temperature gel precipitation / hydrothermal growth, in anoxic conditions) for the synthesis of Fe-serpentines with a controlled Fe2+/Fe3+ ratio in order to improve our understanding of Fe-serpentines formation. XRD analyses of the gels and electron microscopy (SEM, TEM) suggest the formation of Fe-serpentine seeds at room temperature. These germs have integrated significant amounts (up to 24%) of tetrahedral Fe3+, as indicated by Mössbauer spectroscopy. Hydrothermal growth at 60°C yields a clear improvement of crystallinity, further suggesting that Fe-serpentines form at low temperatures, lower than Mg-serpentines. We report that among the samples, whose composition covers the solid solution between greenalite (Fe2+-serpentine) and cronstedtite, crystallinity improves with the Fe/Si and the Fe3+ content, which respective roles remain to be evaluated. In chondrites' parent body, Fe is mostly released by the aqueous alteration of metallic alloys and Fe2+-bearing anhydrous silicates (mostly olivine and pyroxene) and sulfides. We suggest that the formation of cronstedtite, which is associated with the early stages of parent body alteration, might have been kinetically favored by the oxidation of Fe. This raises the question of the processes involved, in the anoxic chondritic environment.

  8. Investigating vibrational relaxation in cyanide-bridged transition metal mixed-valence complexes using two-dimensional infrared and infrared pump-probe spectroscopies

    PubMed Central

    Slenkamp, Karla M.; Lynch, Michael S.; Brookes, Jennifer F.; Bannan, Caitlin C.; Daifuku, Stephanie L.; Khalil, Munira

    2016-01-01

    Using polarization-selective two-dimensional infrared (2D IR) and infrared pump-probe spectroscopies, we study vibrational relaxation of the four cyanide stretching (νCN) vibrations found in [(NH3)5RuIIINCFeII(CN)5]− (FeRu) dissolved in D2O or formamide and [(NC)5FeIICNPtIV(NH3)4NCFeII(CN)5]4− (FePtFe) dissolved in D2O. These cyanide-bridged transition metal complexes serve as models for understanding the role high frequency vibrational modes play in metal-to-metal charge transfers over a bridging ligand. However, there is currently little information about vibrational relaxation and dephasing dynamics of the anharmonically coupled νCN modes in the electronic ground state of these complexes. IR pump-probe experiments reveal that the vibrational lifetimes of the νCN modes are ∼2 times faster when FeRu is dissolved in D2O versus formamide. They also reveal that the vibrational lifetimes of the νCN modes of FePtFe in D2O are almost four times as long as for FeRu in D2O. Combined with mode-specific relaxation dynamics measured from the 2D IR experiments, the IR pump-probe experiments also reveal that intramolecular vibrational relaxation is occurring in all three systems on ∼1 ps timescale. Center line slope dynamics, which have been shown to be a measure of the frequency-frequency correlation function, reveal that the radial, axial, and trans νCN modes exhibit a ∼3 ps timescale for frequency fluctuations. This timescale is attributed to the forming and breaking of hydrogen bonds between each mode and the solvent. The results presented here along with our previous work on FeRu and FePtFe reveal a picture of coupled anharmonic νCN modes where the spectral diffusion and vibrational relaxation dynamics depend on the spatial localization of the mode on the molecular complex and its specific interaction with the solvent. PMID:27158634

  9. Advancing Software Architecture Modeling for Large Scale Heterogeneous Systems

    SciTech Connect

    Gorton, Ian; Liu, Yan

    2010-11-07

    In this paper we describe how incorporating technology-specific modeling at the architecture level can help reduce risks and produce better designs for large, heterogeneous software applications. We draw an analogy with established modeling approaches in scientific domains, using groundwater modeling as an example, to help illustrate gaps in current software architecture modeling approaches. We then describe the advances in modeling, analysis and tooling that are required to bring sophisticated modeling and development methods within reach of software architects.

  10. Optimization of large-scale heterogeneous system-of-systems models.

    SciTech Connect

    Parekh, Ojas; Watson, Jean-Paul; Phillips, Cynthia Ann; Siirola, John; Swiler, Laura Painton; Hough, Patricia Diane; Lee, Herbert K. H.; Hart, William Eugene; Gray, Genetha Anne; Woodruff, David L.

    2012-01-01

    Decision makers increasingly rely on large-scale computational models to simulate and analyze complex man-made systems. For example, computational models of national infrastructures are being used to inform government policy, assess economic and national security risks, evaluate infrastructure interdependencies, and plan for the growth and evolution of infrastructure capabilities. A major challenge for decision makers is the analysis of national-scale models that are composed of interacting systems: effective integration of system models is difficult, there are many parameters to analyze in these systems, and fundamental modeling uncertainties complicate analysis. This project is developing optimization methods to effectively represent and analyze large-scale heterogeneous system of systems (HSoS) models, which have emerged as a promising approach for describing such complex man-made systems. These optimization methods enable decision makers to predict future system behavior, manage system risk, assess tradeoffs between system criteria, and identify critical modeling uncertainties.

  11. Pathological heterogeneity of idiopathic central nervous system inflammatory demyelinating disorders.

    PubMed

    Lucchinetti, C

    2008-01-01

    The last decade has seen a resurgence of interest in MS neuropathology. This resurgence was partly fueled by the development of new molecular and histochemical tools to examine the MS lesion microscopically, as well as technological advances in neuroimaging, which permit a dynamic assessment of lesion formation and disease progression. The heterogeneous pathology of MS in relation to stage of lesion activity, phase of disease, and clinical course is discussed. Pathological studies reveal that the immune factors associated with multiple different effector mechanisms contribute to the inflammation, demyelination, and tissue injury observed in MS lesions. While many agree that pathological heterogeneity exists in white matter demyelinated lesions, it is uncertain whether these observations are patient-dependent and reflect pathogenic heterogeneity or, alternatively, are stage-dependent with multiple mechanisms occurring sequentially within a given patient. Evidence supporting both concepts is presented. Remyelination is present in MS lesions; however, the factors contributing to the extent of repair and oligodendrocyte survival differ depending on the disease phase. A variable and patient-dependent extent of remyelination is observed in chronic MS cases and will likely need to be considered when designing future clinical trials aimed to promote CNS repair. MS is one member of a spectrum of CNS idiopathic inflammatory demyelinating disorders that share the basic pathological hallmark of CNS inflammatory demyelination. Advances based on recent systematic clinicopathologic-serologic correlative approaches have led to novel insights with respect to the classification of these disorders, as well as a better understanding of the underlying pathogenic mechanisms.

  12. Heterogeneity of European DRG systems and potentials for a common EuroDRG system

    PubMed Central

    Geissler, Alexander; Quentin, Wilm; Busse, Reinhard

    2015-01-01

    Diagnosis-Related Group (DRG) systems across Europe are very heterogeneous, in particular because of different classification variables and algorithms as well as costing methodologies. But, given the challenge of increasing patient mobility within Europe, health systems are forced to incorporate a common patient classification language in order to compare and identify similar patients e.g. for reimbursement purposes. Beside the national adoption of DRGs for a wide range of purposes (measuring hospital activity vs. paying hospitals), a common DRG system can serve as an international communication basis among health administrators and can reduce the national development efforts as it is demonstrated by the NordDRG consortium. PMID:25905484

  13. Physics Characterization of a Heterogeneous Sodium Fast Reactor Transmutation System

    SciTech Connect

    Samuel E. Bays

    2007-09-01

    The threshold-fission (fertile) nature of Am-241 is used to destroy this minor actinide by capitalizing upon neutron capture instead of fission within a sodium fast reactor. This neutron-capture and its subsequent decay chain leads to the breeding of even mass number plutonium isotopes. A slightly moderated target design is proposed for breeding plutonium in an axial blanket located above the active “fast reactor” driver fuel region. A parametric study on the core height and fuel pin diameter-to-pitch ratio is used to explore the reactor and fuel cycle aspects of this design. This study resulted in both a non-flattened and a pancake core geometry. Both of these designs demonstrated a high capacity for removing americium from the fuel cycle. A reactivity coefficient analysis revealed that this heterogeneous design will have comparable safety aspects to a homogeneous reactor of the same size.

  14. Computer Interfaces for User Access to Heterogeneous Information-Retrieval Systems.

    ERIC Educational Resources Information Center

    Marcus, Richard S.; Reintjes, J. Francis

    A translating-computer-interface approach to providing a common, or virtual-system, mode of access to a network of heterogeneous online bibliographic retrieval systems has been investigated. Enhanced access to such systems by end users has been demonstrated through test usage of an experimental interface. A table-driven, rule-based message…

  15. Thermodynamic and kinetic analysis of heterogeneous photocatalysis for semiconductor systems.

    PubMed

    Liu, Baoshun; Zhao, Xiujian; Terashima, Chiaki; Fujishima, Akira; Nakata, Kazuya

    2014-05-21

    Since the report of the Honda-Fujishima effect, heterogeneous photocatalysis has attracted much attention around the world because of its potential energy and environmental applications. Although great progresses have been made in recent years, most were focused on preparing highly-active photocatalysts and investigating visible light utilization. In fact, we are still unclear on the thermodynamic and kinetic nature of photocatalysis to date, which sometimes leads to misunderstandings for experimental results. It is timely to give a review and discussion on the thermodynamics and kinetics of photocatalysis, so as to direct future researches. However, there is an absence of a detailed review on this topic until now. In this article, we tried to review and discuss the thermodynamics and kinetics of photocatalysis. We explained the thermodynamic driving force of photocatalysis, and distinguished the functions of light and heat in photocatalysis. The Langmuir-Hinshelwood kinetic model, the ˙OH oxidation mechanism, and the direct-indirect (D-I) kinetic model were reviewed and compared. Some applications of the D-I model to study photocatalytic kinetics were also discussed. The electron transport mode and its importance in photocatalysis were investigated. Finally, the intrinsic relation between the kinetics and the thermodynamics of photocatalytic reactions was discussed.

  16. Controllability of heterogeneous multi-agent systems under directed and weighted topology

    NASA Astrophysics Data System (ADS)

    Guan, Yongqiang; Ji, Zhijian; Zhang, Lin; Wang, Long

    2016-05-01

    This paper considers the controllability problem for both continuous- and discrete-time linear heterogeneous multi-agent systems with directed and weighted communication topology. First, two kinds of neighbour-based control protocols based on the distributed protocol of first-order and second-order multi-agent systems are proposed, under which it is shown that a heterogeneous multi-agent system is controllable if the underlying communication topology is controllable. Then, under special leader selection, the result shows that the controllability of a heterogeneous multi-agent system is solely decided by its communication topology graph. Furthermore, some necessary and/or sufficient conditions are derived for controllability of communication topology from algebraic and graphical perspectives. Finally, simulation examples are presented to demonstrate the effectiveness of the theoretical results.

  17. Reliability Inherent in Heterogeneous Multiprocessor Systems and Task Scheduling for Ameliorating Their Reliability

    NASA Astrophysics Data System (ADS)

    Sugihara, Makoto

    Utilizing a heterogeneous multiprocessor system has become a popular design paradigm to build an embedded system at a cheap cost within short development time. A reliability issue for embedded systems, which is vulnerability to single event upsets (SEUs), has become a matter of concern as technology proceeds. This paper discusses reliability inherent in heterogeneous multiprocessors and proposes task scheduling for minimizing SEU vulnerability of them. This paper experimentally shows that increasing performance of a CPU core deteriorates its reliability. Based on the experimental observation, we propose task scheduling for reducing SEU vulnerability of a heterogeneous multiprocessor system. The experimental results demonstrate that our task scheduling technique can reduce much of SEU vulnerability under real-time constraints.

  18. Decomposing the dynamics of heterogeneous delayed networks with applications to connected vehicle systems.

    PubMed

    Szalai, Róbert; Orosz, Gábor

    2013-10-01

    Delay-coupled networks are investigated with nonidentical delay times and the effects of such heterogeneity on the emergent dynamics of complex systems are characterized. A simple decomposition method is presented that decouples the dynamics of the network into node-size modal equations in the vicinity of equilibria. The resulting independent components contain distributed delays that map the spatiotemporal complexity of the system to the time domain. We demonstrate that this approach can be used to reveal physical phenomena in heterogenous vehicular traffic when vehicles are linked via vehicle-to-vehicle communication.

  19. A service platform architecture design towards a light integration of heterogeneous systems in the wellbeing domain.

    PubMed

    Yang, Yaojin; Ahtinen, Aino; Lahteenmaki, Jaakko; Nyman, Petri; Paajanen, Henrik; Peltoniemi, Teijo; Quiroz, Carlos

    2007-01-01

    System integration is one of the major challenges for building wellbeing or healthcare related information systems. In this paper, we are going to share our experiences on how to design a service platform called Nuadu service platform, for providing integrated services in occupational health promotion and health risk management through two heterogeneous systems. Our design aims for a light integration covering the layers, from data through service up to presentation, while maintaining the integrity of the underlying systems.

  20. Single crystal X-ray diffraction study of a mixed-valence gold compound, Cs{sub 2}Au{sup I}Au{sup III}Cl{sub 6} under high pressures up to 18 GPa: Pressure-induced phase transition coupled with gold valence transition

    SciTech Connect

    Matsushita, Nobuyuki Ahsbahs, Hans; Hafner, Stefan S.; Kojima, Norimichi

    2007-04-15

    We performed the single-crystal X-ray diffraction study of a perovskite-type gold mixed-valence compound, Cs{sub 2}Au{sup I}Au{sup III}Cl{sub 6}, under high pressures up to 18 GPa by using a diamond-anvil-cell with helium gas as an ideal hydrostatic pressure-transmitting medium. The lattice parameters and the variable atomic positional parameters were obtained with reasonable accuracy at various pressures. A structural phase transition at ca. 12.5 GPa from I4/mmm to Pm3m was found. The lattice parameters a {sub 0} and c {sub 0}, denoted in the tetragonal cell setting, result in the relationship 2{sup 1/2} a {sub 0}=c {sub 0}, and the superstructure reflections h k l (l is odd), caused by the shift of the Cl ions from the midpoint of the Au ions, disappeared at pressures above the phase transition. Both elongated [Au{sup III}Cl{sub 6}] and compressed [Au{sup I}Cl{sub 6}] octahedra in the low-pressure phase smoothly approach regular octahedra with increasing pressure. Above the structural phase transition at 12.5 GPa, all the [AuCl{sub 6}] octahedra are crystallographically equivalent, which shows that the tetragonal-to-cubic phase transition accompanies the valence transition from the Au{sup I}/Au{sup III} mixed-valence state to the Au{sup II} single-valence state. - Graphical abstract: Single-crystal X-ray diffraction study under high pressures up to 18 GPa by using a diamond-anvil-cell with helium gas as an ideal hydrostatic pressure medium has revealed that a perovskite-type gold mixed-valence compound, Cs{sub 2}Au{sup I}Au{sup III}Cl{sub 6}, exhibits the structural phase transition from tetragonal to cubic at 12.5 GPa accompanying gold valence transition.

  1. Dense, Viscous Brine Behavior in Heterogeneous Porous Medium Systems

    PubMed Central

    Wright, D. Johnson; Pedit, J.A.; Gasda, S.E.; Farthing, M.W.; Murphy, L.L.; Knight, S.R.; Brubaker, G.R.

    2010-01-01

    The behavior of dense, viscous calcium bromide brine solutions used to remediate systems contaminated with dense nonaqueous phase liquids (DNAPLs) is considered in laboratory and field porous medium systems. The density and viscosity of brine solutions are experimentally investigated and functional forms fit over a wide range of mass fractions. A density of 1.7 times, and a corresponding viscosity of 6.3 times, that of water is obtained at a calcium bromide mass fraction of 0.53. A three-dimensional laboratory cell is used to investigate the establishment, persistence, and rate of removal of a stratified dense brine layer in a controlled system. Results from a field-scale experiment performed at the Dover National Test Site are used to investigate the ability to establish and maintain a dense brine layer as a component of a DNAPL recovery strategy, and to recover the brine at sufficiently high mass fractions to support the economical reuse of the brine. The results of both laboratory and field experiments show that a dense brine layer can be established, maintained, and recovered to a significant extent. Regions of unstable density profiles are shown to develop and persist in the field-scale experiment, which we attribute to regions of low hydraulic conductivity. The saturated-unsaturated, variable-density ground-water flow simulation code SUTRA is modified to describe the system of interest, and used to compare simulations to experimental observations and to investigate certain unobserved aspects of these complex systems. The model results show that the standard model formulation is not appropriate for capturing the behavior of sharp density gradients observed during the dense brine experiments. PMID:20444520

  2. Dense, viscous brine behavior in heterogeneous porous medium systems.

    PubMed

    Wright, D Johnson; Pedit, J A; Gasda, S E; Farthing, M W; Murphy, L L; Knight, S R; Brubaker, G R; Miller, C T

    2010-06-25

    The behavior of dense, viscous calcium bromide brine solutions used to remediate systems contaminated with dense nonaqueous phase liquids (DNAPLs) is considered in laboratory and field porous medium systems. The density and viscosity of brine solutions are experimentally investigated and functional forms fit over a wide range of mass fractions. A density of 1.7 times, and a corresponding viscosity of 6.3 times, that of water is obtained at a calcium bromide mass fraction of 0.53. A three-dimensional laboratory cell is used to investigate the establishment, persistence, and rate of removal of a stratified dense brine layer in a controlled system. Results from a field-scale experiment performed at the Dover National Test Site are used to investigate the ability to establish and maintain a dense brine layer as a component of a DNAPL recovery strategy, and to recover the brine at sufficiently high mass fractions to support the economical reuse of the brine. The results of both laboratory and field experiments show that a dense brine layer can be established, maintained, and recovered to a significant extent. Regions of unstable density profiles are shown to develop and persist in the field-scale experiment, which we attribute to regions of low hydraulic conductivity. The saturated-unsaturated, variable-density groundwater flow simulation code SUTRA is modified to describe the system of interest, and used to compare simulations to experimental observations and to investigate certain unobserved aspects of these complex systems. The model results show that the standard model formulation is not appropriate for capturing the behavior of sharp density gradients observed during the dense brine experiments.

  3. Molecular Supertetrahedron Decorated with Exposed Sulfonate Groups Built from Mixed-Valence Tetranuclear Fe[subscript 3 superscript 3+]Fe[superscript 2+]([mu subscript 3]-Ο)([mu subscript 3]-SO[subscript 4])[subscript 3](−CO[subscript 2])[subscript 3] Clusters

    SciTech Connect

    Papadaki, Ioanna; Malliakas, Christos D.; Bakas, Thomas; Trikalitis, Pantelis N.

    2009-12-01

    We present the synthesis and characterization of a novel metal-organic molecular solid using the ligand 4,8-disulfonaphthalene-2,6-dicarboxylic acid. The solid features a sulfonated, isolated supertetrahedra, [Fe{sub 16}O{sub 4}(SO{sub 4}){sub 12}(L2){sub 6}], built from mixed-valence [Fe{sub 3}{sup 3+}Fe{sup 2+}({mu}{sub 3}-O)({mu}{sub 3}-SO{sub 4}){sub 3}(-CO{sub 2}){sub 3}] clusters.

  4. Database interfaces on NASA's heterogeneous distributed database system

    NASA Technical Reports Server (NTRS)

    Huang, Shou-Hsuan Stephen

    1987-01-01

    The purpose of Distributed Access View Integrated Database (DAVID) interface module (Module 9: Resident Primitive Processing Package) is to provide data transfer between local DAVID systems and resident Data Base Management Systems (DBMSs). The result of current research is summarized. A detailed description of the interface module is provided. Several Pascal templates were constructed. The Resident Processor program was also developed. Even though it is designed for the Pascal templates, it can be modified for templates in other languages, such as C, without much difficulty. The Resident Processor itself can be written in any programming language. Since Module 5 routines are not ready yet, there is no way to test the interface module. However, simulation shows that the data base access programs produced by the Resident Processor do work according to the specifications.

  5. System level traffic shaping in disk servers with heterogeneous protocols

    NASA Astrophysics Data System (ADS)

    Cano, Eric; Kruse, Daniele Francesco

    2014-06-01

    Disk access and tape migrations compete for network bandwidth in CASTORs disk servers, over various protocols: RFIO, Xroot, root and GridFTP. As there are a limited number of tape drives, it is important to keep them busy all the time, at their nominal speed. With potentially 100s of user read streams per server, the bandwidth for the tape migrations has to be guaranteed to a controlled level, and not the fair share the system gives by default. Xroot provides a prioritization mechanism, but using it implies moving exclusively to the Xroot protocol, which is not possible in short to mid-term time frame, as users are equally using all protocols. The greatest commonality of all those protocols is not more than the usage of TCP/IP. We investigated the Linux kernel traffic shaper to control TCP/ IP bandwidth. The performance and limitations of the traffic shaper have been understood in test environment, and satisfactory working point has been found for production. Notably, TCP offload engines' negative impact on traffic shaping, and the limitations of the length of the traffic shaping rules were discovered and measured. A suitable working point has been found and the traffic shaping is now successfully deployed in the CASTOR production systems at CERN. This system level approach could be transposed easily to other environments.

  6. Differentiation and heterogeneity in the mononuclear phagocyte system.

    PubMed

    Hume, D A

    2008-11-01

    Cells of the mononuclear phagocyte system (MPS) are found in large numbers in every organ of the body, where they contribute to innate and acquired immunity and homeostasis. This review considers the locations of MPS cells, surface markers that distinguish subsets of monocytes and macrophages, the pathways of MPS differentiation, and the growth factors and transcription factors that guide them. Although the number of MPS sub-populations that can be defined is infinite, the features that unite the MPS remain compelling. Those features clearly include antigen-presenting dendritic cells within the MPS and argue against any basis for separating them from macrophages.

  7. Pancreatic cancer: systemic combination therapies for a heterogeneous disease.

    PubMed

    Melisi, Davide; Calvetti, Lorenzo; Frizziero, Melissa; Tortora, Giampaolo

    2014-01-01

    Pancreatic cancer is the only human malignancy for which patients' survival has not improved substantially during the past 30 years. Despite advances in the comprehension of the molecular mechanisms underlying pancreatic carcinogenesis, current systemic treatments offer only a modest benefit in tumor-related symptoms and survival. Over the past decades, gemcitabine and its combination with other standard cytotoxic agents have been the reference treatments for advanced pancreatic cancer patients. The recent introduction of the three-drug combination regimen FOLFIRINOX or the new taxane nab-paclitaxel represent key advances for a better control of the disease. Novel agents targeting molecular mechanisms involved in cancer development and maintenance are currently under clinical investigation. This review describes the most important findings in the field of systemic combination therapies for the treatment of pancreatic cancer. We discuss the emerging evidences for the clinical activity of combination treatments with standard chemotherapy plus novel agents targeting tumor cell-autonomous and tumor microenvironment signaling pathways. We present some of the most important advances in the comprehension of the molecular mechanisms responsible for the chemoresistance of pancreatic cancer and the emerging therapeutic targets to overcome this resistance.

  8. Energy-aware Thread and Data Management in Heterogeneous Multi-core, Multi-memory Systems

    SciTech Connect

    Su, Chun-Yi

    2014-12-16

    By 2004, microprocessor design focused on multicore scaling—increasing the number of cores per die in each generation—as the primary strategy for improving performance. These multicore processors typically equip multiple memory subsystems to improve data throughput. In addition, these systems employ heterogeneous processors such as GPUs and heterogeneous memories like non-volatile memory to improve performance, capacity, and energy efficiency. With the increasing volume of hardware resources and system complexity caused by heterogeneity, future systems will require intelligent ways to manage hardware resources. Early research to improve performance and energy efficiency on heterogeneous, multi-core, multi-memory systems focused on tuning a single primitive or at best a few primitives in the systems. The key limitation of past efforts is their lack of a holistic approach to resource management that balances the tradeoff between performance and energy consumption. In addition, the shift from simple, homogeneous systems to these heterogeneous, multicore, multi-memory systems requires in-depth understanding of efficient resource management for scalable execution, including new models that capture the interchange between performance and energy, smarter resource management strategies, and novel low-level performance/energy tuning primitives and runtime systems. Tuning an application to control available resources efficiently has become a daunting challenge; managing resources in automation is still a dark art since the tradeoffs among programming, energy, and performance remain insufficiently understood. In this dissertation, I have developed theories, models, and resource management techniques to enable energy-efficient execution of parallel applications through thread and data management in these heterogeneous multi-core, multi-memory systems. I study the effect of dynamic concurrent throttling on the performance and energy of multi-core, non-uniform memory access

  9. Cooperative effects of parameter heterogeneity and coupling on coherence resonance in unidirectional coupled brusselator system

    NASA Astrophysics Data System (ADS)

    Li, Qian-Shu; Shi, Jian-Cheng

    2007-01-01

    Two unidirectional coupled brusselator systems, subject to common and uncorrelated multiplicative noise, are investigated, respectively. It can be found that, the parameter heterogeneity effect may be destroyed above critical coupling strength. Synchronization occurs between subsystems subjected to common noise, but cannot achieve by means of uncorrelated noise.

  10. On possible Mn-53 heterogeneity in the early solar system

    NASA Technical Reports Server (NTRS)

    Lavrukhina, A. K.; Ustinova, G. K.

    1993-01-01

    The effects of influence of shock wave propagation on the energy spectrum of accelerated particles that lead to different production rates of radionuclides, in particular, Mn-53, on small scales in the early solar system are shown. Search for evidence for extinct Mn-53 has stimulated investigations of Cr isotope anomalies in meteorites. The linear correlation between the magnitude of the Cr-53* excesses and the Mn/Cr ratio that unambiguously proves the in situ decay of Mn-53 was detected, really, in different mineral phases of some carbonaceous and enstatite chondrites, primitive achondrites, pallasites and iron meteorites. However, the data on the Cr-53* excess rarely defines a single linear array on a Mn-53-Cr-52 evolution diagram even for meteorites of the same chemical group. A clear isochron with Mn-53/Mn-55 = 4.4 plus or minus 1.0 x 10(exp -5) (in range of approximately 2.4 to approximately 9 x 10(exp -5)) is observed for CAI of the Allende C3-chondrite while the data for the Murchison C2- and Orgueil C1-chondrites fall much lower corresponding rather to Mn-53/Mn-55 less than 2 x 10(exp -5). In the case of iron meteorites it ranges from less than 5 x 10(exp -8) to less than 5 x 10(exp -5).

  11. Investigation of detonation velocity in heterogeneous explosive system using the reactive Burgers' analog

    NASA Astrophysics Data System (ADS)

    Di Labbio, G.; Kiyanda, C. B.; Mi, X.; Higgins, A. J.; Nikiforakis, N.; Ng, H. D.

    2016-06-01

    In this study, the applicability of the Chapman-Jouguet (CJ) criterion is tested numerically for heterogeneous explosive media using a simple detonation analog. The analog system consists of a reactive Burgers' equation coupled with an Arrhenius type reaction wave, and the heterogeneity of the explosive media is mimicked using a discrete energy source approach. The governing equation is solved using a second order, finite-volume approach and the average propagation velocity of the discrete detonation is determined by tracking the leading shock front. Consistent with previous studies, the averaged velocity of the leading shock front from the unsteady numerical simulations is also found to be in good agreement with the velocity of a CJ detonation in a uniform medium wherein the energy source is spatially homogenized. These simulations have thus implications for whether the CJ criterion is valid to predict the detonation velocity in heterogeneous explosive media.

  12. A Thin Film of an Ni NiO Heterogeneous System for an Optical Recording Medium

    NASA Astrophysics Data System (ADS)

    Iida, Atsuko; Nishikawa, Reiji

    1994-07-01

    The authors have found a write once read many (WORM) type new optical recording medium of an Ni NiO heterogeneous system thin film. The structure of the recording medium is a single layer Ni NiO heterogeneous thin film on a transparent resin substrate. Irradiation of a converged laser diode beam causes a volume expansion of the film to form a swell. Information reading is done by using its reduction in reflectivity. The recordable composition region of this film is considered to be the transitive region from the metal to the oxide. The volume expansion is assumed to be induced by the oxidation of the Ni NiO heterogeneous thin film and the height of the swell is estimated. This value agrees well with the measured top height of the swell.

  13. A Java-based teleradiology system to provide services over a heterogeneous network.

    PubMed

    Elkateeb, A; Richardson, P; Kawaja, A; Rahme, P

    2001-01-01

    This paper describes a teleradiology system developed to provide services over a heterogeneous networks environment. The system can transfer radiology images and provide real-time consultations and diagnostics over the telephone, Integrated Service Digital Network (ISDN), as well as a generic hospital network. The network incorporates Ethernet Local Area Network (LAN), ATM switches, and an IP router. The Java Language is used in developing this system. This teleradiology system is flexible, effective, and provides for high performance for end users. The system has been tested over all above networks and the results have shown that the system is robust and efficient. PMID:11564359

  14. Crystal structure of μ-cyanido-1:2κ2 N:C-dicyanido-1κC,2κC-bis­(quinolin-8-amine-1κ2 N,N′)-2-silver(I)-1-silver(II): rare occurrence of a mixed-valence AgI,II compound

    PubMed Central

    Setifi, Zouaoui; Bernès, Sylvain; Pérez, Olivier; Setifi, Fatima; Rouag, Djamil-Azzeddine

    2015-01-01

    The title dinuclear complex, [Ag2(CN)3(C9H8N2)2], may be considered as an AgII compound with the corresponding metal site coordinated by two bidentate quinolin-8-amine mol­ecules, one cyanide group and one dicyanidoargentate(I) anion, [Ag(CN)2]−. Since this latter ligand contains an AgI atom, the complex should be a class 1 or class 2 mixed-valence compound, according to the Robin–Day classification. The AgII atom is six-coordinated in a highly distorted octa­hedral geometry, while the AgI atom displays the expected linear geometry. In the crystal, the amino groups of the quinolin-8-amine ligands form N—H⋯N hydrogen bonds with the N atoms of the non-bridging cyanide ligands, forming a two-dimensional network parallel to (102). The terminal cyanide ligands are not engaged in polymeric bonds and the title compound is an authentic mol­ecular complex. The title mol­ecule is thus a rare example of a stable AgI,II complex, and the first mixed-valence AgI,II mol­ecular complex characterized by X-ray diffraction. PMID:26090154

  15. Effects of three-dimensional geometric field focusing on concentration polarization in a heterogeneous permselective system

    NASA Astrophysics Data System (ADS)

    Green, Yoav; Yossifon, Gilad

    2014-01-01

    The current study extends previous two-dimensional (2D) analysis of concentration polarization to account for three-dimensional effects in realistic heterogeneous ion-permselective systems, e.g., microchamber-nanoslot devices. An analytical solution of the electrodiffusive problem, decoupled from electroconvection along with the local electroneutrality approximation, was obtained using the separation of variables technique. It is able to account for the previously neglected effects of microchamber and nanoslot heights on concentration polarization in terms of concentration profiles, limiting current, and current-voltage curves. The resultant heterogeneity in the third dimension adds to that already existing in the 2D in plane problem to further increase geometric field-focusing effects. As a result the currents no longer scale linearly with the nanoslot area, but rather depend on its shape and relative size compared to that of the nonconducting region (i.e., level of heterogeneity). This is turn leads to pronounced current density intensification with increased system heterogeneity found to be in qualitative agreement with previously reported experiments in which both microchamber and nanoslot geometries were varied.

  16. Time Utility Functions for Modeling and Evaluating Resource Allocations in a Heterogeneous Computing System

    SciTech Connect

    Briceno, Luis Diego; Khemka, Bhavesh; Siegel, Howard Jay; Maciejewski, Anthony A; Groer, Christopher S; Koenig, Gregory A; Okonski, Gene D; Poole, Stephen W

    2011-01-01

    This study considers a heterogeneous computing system and corresponding workload being investigated by the Extreme Scale Systems Center (ESSC) at Oak Ridge National Laboratory (ORNL). The ESSC is part of a collaborative effort between the Department of Energy (DOE) and the Department of Defense (DoD) to deliver research, tools, software, and technologies that can be integrated, deployed, and used in both DOE and DoD environments. The heterogeneous system and workload described here are representative of a prototypical computing environment being studied as part of this collaboration. Each task can exhibit a time-varying importance or utility to the overall enterprise. In this system, an arriving task has an associated priority and precedence. The priority is used to describe the importance of a task, and precedence is used to describe how soon the task must be executed. These two metrics are combined to create a utility function curve that indicates how valuable it is for the system to complete a task at any given moment. This research focuses on using time-utility functions to generate a metric that can be used to compare the performance of different resource schedulers in a heterogeneous computing system. The contributions of this paper are: (a) a mathematical model of a heterogeneous computing system where tasks arrive dynamically and need to be assigned based on their priority, precedence, utility characteristic class, and task execution type, (b) the use of priority and precedence to generate time-utility functions that describe the value a task has at any given time, (c) the derivation of a metric based on the total utility gained from completing tasks to measure the performance of the computing environment, and (d) a comparison of the performance of resource allocation heuristics in this environment.

  17. FOREWORD: Heterogenous nucleation and microstructure formation—a scale- and system-bridging approach Heterogenous nucleation and microstructure formation—a scale- and system-bridging approach

    NASA Astrophysics Data System (ADS)

    Emmerich, H.

    2009-11-01

    Scope and aim of this volume. Nucleation and initial microstructure formation play an important role in almost all aspects of materials science [1-5]. The relevance of the prediction and control of nucleation and the subsequent microstructure formation is fully accepted across many areas of modern surface and materials science and technology. One reason is that a large range of material properties, from mechanical ones such as ductility and hardness to electrical and magnetic ones such as electric conductivity and magnetic hardness, depend largely on the specific crystalline structure that forms in nucleation and the subsequent initial microstructure growth. A very demonstrative example for the latter is the so called bamboo structure of an integrated circuit, for which resistance against electromigration [6] , a parallel alignment of grain boundaries vertical to the direction of electricity, is most favorable. Despite the large relevance of predicting and controlling nucleation and the subsequent microstructure formation, and despite significant progress in the experimental analysis of the later stages of crystal growth in line with new theoretical computer simulation concepts [7], details about the initial stages of solidification are still far from being satisfactorily understood. This is in particular true when the nucleation event occurs as heterogenous nucleation. The Priority Program SPP 1296 'Heterogenous Nucleation and Microstructure Formation—a Scale- and System-Bridging Approach' [8] sponsored by the German Research Foundation, DFG, intends to contribute to this open issue via a six year research program that enables approximately twenty research groups in Germany to work interdisciplinarily together following this goal. Moreover, it enables the participants to embed themselves in the international community which focuses on this issue via internationally open joint workshops, conferences and summer schools. An outline of such activities can be found

  18. Spatial snowdrift game in heterogeneous agent systems with co-evolutionary strategies and updating rules

    NASA Astrophysics Data System (ADS)

    Xia, Hai-Jiang; Li, Ping-Ping; Ke, Jian-Hong; Lin, Zhen-Quan

    2015-04-01

    We propose an evolutionary snowdrift game model for heterogeneous systems with two types of agents, in which the inner-directed agents adopt the memory-based updating rule while the copycat-like ones take the unconditional imitation rule; moreover, each agent can change his type to adopt another updating rule once the number he sequentially loses the game at is beyond his upper limit of tolerance. The cooperative behaviors of such heterogeneous systems are then investigated by Monte Carlo simulations. The numerical results show the equilibrium cooperation frequency and composition as functions of the cost-to-benefit ratio r are both of plateau structures with discontinuous steplike jumps, and the number of plateaux varies non-monotonically with the upper limit of tolerance νT as well as the initial composition of agents fa0. Besides, the quantities of the cooperation frequency and composition are dependent crucially on the system parameters including νT, fa0, and r. One intriguing observation is that when the upper limit of tolerance is small, the cooperation frequency will be abnormally enhanced with the increase of the cost-to-benefit ratio in the range of 0 < r < 1/4. We then probe into the relative cooperation frequencies of either type of agents, which are also of plateau structures dependent on the system parameters. Our results may be helpful to understand the cooperative behaviors of heterogenous agent systems. Project supported by the National Natural Science Foundation of China (Grant Nos. 11175131 and 10875086).

  19. Cross-platform distributed heterogeneous simulation of a more-electric aircraft power system

    NASA Astrophysics Data System (ADS)

    Lucas, C. E.; Walters, E. A.; Wasynczuk, O.; Lamm, P. T.

    2005-05-01

    To support research and analysis requirements in the development of future power systems, a flexible and efficient means of predicting the dynamic performance of large-scale multi-disciplinary systems prior to hardware trials is crucial. With the development of Distributed Heterogeneous Simulation (DHS), the technology now exists to enable this type of investigation. Previously, DHS was shown to allow the interconnection of component simulations running on a single- or distributed-computer network and developed using any combination of a variety of commercial-off-the-shelf (COTS) software packages for the Microsoft Windows operating system. However, for large-scale systems, all subsystem models may not be developed in software packages operating under Windows thereby requiring a translation of such models in order to incorporate them within a system simulation. In this paper, the DHS technique is expanded to support the UNIX operating system, thus, allowing subsystem models developed and executed on either UNIX- or Windows-based computers to be interconnected to form a dynamic system simulation. For the purpose of demonstration, a more-electric fighter (MEF) power system, such as that found on the Joint Strike Fighter (JSF), has been selected as a study system. This system is comprised of ten component models each developed using MATLAB/Simulink, EASY5, or ACSL. Utilizing the system simulation, studies have been performed to illustrate the dynamic interactions between the subsystems when simulated on a heterogeneous computer network containing both Windows- and Unix-based machines.

  20. Revisiting the Stability of Spatially Heterogeneous Predator-Prey Systems Under Eutrophication.

    PubMed

    Farkas, J Z; Morozov, A Yu; Arashkevich, E G; Nikishina, A

    2015-10-01

    We employ partial integro-differential equations to model trophic interaction in a spatially extended heterogeneous environment. Compared to classical reaction-diffusion models, this framework allows us to more realistically describe the situation where movement of individuals occurs on a faster time scale than on the demographic (population) time scale, and we cannot determine population growth based on local density. However, most of the results reported so far for such systems have only been verified numerically and for a particular choice of model functions, which obviously casts doubts about these findings. In this paper, we analyse a class of integro-differential predator-prey models with a highly mobile predator in a heterogeneous environment, and we reveal the main factors stabilizing such systems. In particular, we explore an ecologically relevant case of interactions in a highly eutrophic environment, where the prey carrying capacity can be formally set to 'infinity'. We investigate two main scenarios: (1) the spatial gradient of the growth rate is due to abiotic factors only, and (2) the local growth rate depends on the global density distribution across the environment (e.g. due to non-local self-shading). For an arbitrary spatial gradient of the prey growth rate, we analytically investigate the possibility of the predator-prey equilibrium in such systems and we explore the conditions of stability of this equilibrium. In particular, we demonstrate that for a Holling type I (linear) functional response, the predator can stabilize the system at low prey density even for an 'unlimited' carrying capacity. We conclude that the interplay between spatial heterogeneity in the prey growth and fast displacement of the predator across the habitat works as an efficient stabilizing mechanism. These results highlight the generality of the stabilization mechanisms we find in spatially structured predator-prey ecological systems in a heterogeneous environment.

  1. MODFLOW procedure to simulate axisymmetric flow in radially heterogeneous and layered aquifer systems

    NASA Astrophysics Data System (ADS)

    Louwyck, Andy; Vandenbohede, Alexander; Bakker, Mark; Lebbe, Luc

    2014-08-01

    A procedure is outlined to simulate axisymmetric groundwater flow in radially heterogeneous and layered aquifer systems using the unmodified version of MODFLOW. The procedure is straightforward, as it only requires correction of some of the input parameters. In contrast to other MODFLOW procedures to simulate axisymmetric flow, no restrictions are imposed on the type of flow, the discretization of radial distance, or the parameter values. Hence, the method can deal with both confined and unconfined flow, wellbore storage, and axisymmetric aquifer inhomogeneities including effects of finite-thickness skin and gravel pack. Several test cases are presented, which compare the calculated results with existing analytical solutions, the analytic element solver TTim, and the axisymmetric, finite-difference model MAxSym. It is concluded that the MODFLOW procedure is capable of simulating accurately axisymmetric flow in radially heterogeneous multi-aquifer systems.

  2. How to ensure sustainable interoperability in heterogeneous distributed systems through architectural approach.

    PubMed

    Pape-Haugaard, Louise; Frank, Lars

    2011-01-01

    A major obstacle in ensuring ubiquitous information is the utilization of heterogeneous systems in eHealth. The objective in this paper is to illustrate how an architecture for distributed eHealth databases can be designed without lacking the characteristic features of traditional sustainable databases. The approach is firstly to explain traditional architecture in central and homogeneous distributed database computing, followed by a possible approach to use an architectural framework to obtain sustainability across disparate systems i.e. heterogeneous databases, concluded with a discussion. It is seen that through a method of using relaxed ACID properties on a service-oriented architecture it is possible to achieve data consistency which is essential when ensuring sustainable interoperability.

  3. Architectural design and support for knowledge sharing across heterogeneous MAST systems

    NASA Astrophysics Data System (ADS)

    Arkin, Ronald C.; Garcia-Vergara, Sergio; Lee, Sung G.

    2012-06-01

    A novel approach for the sharing of knowledge between widely heterogeneous robotic agents is presented, drawing upon Gardenfors Conceptual Spaces approach [4]. The target microrobotic platforms considered are computationally, power, sensor, and communications impoverished compared to more traditional robotics platforms due to their small size. This produces novel challenges for the system to converge on an interpretation of events within the world, in this case specifically focusing on the task of recognizing the concept of a biohazard in an indoor setting.

  4. Bulk magnetization and 1H NMR spectra of magnetically heterogeneous model systems

    SciTech Connect

    Levin, E M; Bud' ko, S L

    2011-04-28

    Bulk magnetization and ¹H static and magic angle spinning (MAS) nuclear magnetic resonance (NMR) spectra of two magnetically heterogeneous model systems based on laponite (LAP) layered silicate or polystyrene (PS) with low and high proton concentration, respectively, and ferrimagnetic Fe₂O₃ nano- or micro-particles have been studied. In LAP+Fe₂O₃, a major contribution to the NMR signal broadening is due to the dipolar coupling between the magnetic moments of protons and magnetic particles. In PS+Fe₂O₃, due to the higher proton concentration in polystyrene and stronger proton–proton dipolar coupling, an additional broadening is observed, i.e. ¹H MAS NMR spectra of magnetically heterogeneous systems are sensitive to both proton–magnetic particles and proton–proton dipolar couplings. An increase of the volume magnetization by ~1 emu/cm³ affects the ¹H NMR signal width in a way that is similar to an increase of the proton concentration by ~2×10²²/cm³. ¹H MAS NMR spectra, along with bulk magnetization measurements, allow the accurate determination of the hydrogen concentration in magnetically heterogeneous systems.

  5. How to Represent 100-meter Spatial Heterogeneity in Earth System Models

    NASA Astrophysics Data System (ADS)

    Chaney, Nathaniel; Shevliakova, Elena; Malyshev, Sergey

    2016-04-01

    Terrestrial ecosystems play a pivotal role in the Earth system; they have a profound impact on the global climate, food and energy production, freshwater resources, and biodiversity. One of the most fascinating yet challenging aspects of characterizing terrestrial ecosystems is their field-scale (~100 m) spatial heterogeneity. It has been observed repeatedly that the water, energy, and biogeochemical cycles at multiple temporal and spatial scales have deep ties to an ecosystem's spatial structure. Current Earth system models largely disregard this important relationship leading to an inadequate representation of ecosystem dynamics. In this presentation, we will show how existing hyperresolution environmental datasets can be harnessed to explicitly represent field-scale spatial heterogeneity in Earth system models. For each macroscale grid cell, these environmental data are clustered according to their field-scale soil and topographic attributes to define unique sub-grid tiles or hydrologic response units (HRUs). The novel Geophysical Fluid Dynamics Laboratory (GFDL) LM3-TiHy-PPA land model is then used to simulate these HRUs and their spatial interactions via the exchange of water, energy, and nutrients along explicit topographic gradients. Using historical simulations over the contiguous United States, we will show how a robust representation of field-scale spatial heterogeneity impacts modeled ecosystem dynamics including the water, energy, and biogeochemical cycles as well as vegetation composition and distribution.

  6. Local chemical potentials and pressures in heterogeneous systems: Adsorptive, absorptive, interfaces

    NASA Astrophysics Data System (ADS)

    Tovbin, Yu. K.

    2016-07-01

    Equations self-consistently describing chemical and mechanical equilibria in heterogeneous systems are derived. The equations are based on the lattice gas model using discrete distributions of molecules in space (on a scale comparable to molecular size) and continuum distributions of molecules (at short distances inside the cells) during their translational and vibrational motions. It is shown that the theory provides a unified description of the equilibrium distributions of molecules in three aggregate states and at their interfaces. Potential functions of intermolecular interactions (such as Mie pair potentials) in several coordination spheres that determine the compressibility of the lattice structure are considered. For simplicity, it is assumed that differences between the sizes of mixture components are small. Expressions for the local components of the pressure tensor inside multicomponent solid phases and heterogeneous systems (adsorptive, absorptive, and interfaces) are obtained. It is established that they can be used to calculate the lattice parameters of deforming phases and the thermodynamic characteristics of interfaces, including surface tension. The tensor nature of the chemical potential in heterogeneous systems is discussed.

  7. Dynamic arrest in charged colloidal systems exhibiting large-scale structural heterogeneities.

    PubMed

    Haro-Pérez, C; Rojas-Ochoa, L F; Castañeda-Priego, R; Quesada-Pérez, M; Callejas-Fernández, J; Hidalgo-Alvarez, R; Trappe, V

    2009-01-01

    Suspensions of charged liposomes are found to exhibit typical features of strongly repulsive fluid systems at short length scales, while exhibiting structural heterogeneities at larger length scales that are characteristic of attractive systems. We model the static structure factor of these systems using effective pair interaction potentials composed of a long-range attraction and a shorter range repulsion. Our modeling of the static structure yields conditions for dynamically arrested states at larger volume fractions, which we find to agree with the experimentally observed dynamics. PMID:19257245

  8. Dynamic arrest in charged colloidal systems exhibiting large-scale structural heterogeneities.

    PubMed

    Haro-Pérez, C; Rojas-Ochoa, L F; Castañeda-Priego, R; Quesada-Pérez, M; Callejas-Fernández, J; Hidalgo-Alvarez, R; Trappe, V

    2009-01-01

    Suspensions of charged liposomes are found to exhibit typical features of strongly repulsive fluid systems at short length scales, while exhibiting structural heterogeneities at larger length scales that are characteristic of attractive systems. We model the static structure factor of these systems using effective pair interaction potentials composed of a long-range attraction and a shorter range repulsion. Our modeling of the static structure yields conditions for dynamically arrested states at larger volume fractions, which we find to agree with the experimentally observed dynamics.

  9. Dynamic Arrest in Charged Colloidal Systems Exhibiting Large-Scale Structural Heterogeneities

    SciTech Connect

    Haro-Perez, C.; Callejas-Fernandez, J.; Hidalgo-Alvarez, R.; Rojas-Ochoa, L. F.; Castaneda-Priego, R.; Quesada-Perez, M.; Trappe, V.

    2009-01-09

    Suspensions of charged liposomes are found to exhibit typical features of strongly repulsive fluid systems at short length scales, while exhibiting structural heterogeneities at larger length scales that are characteristic of attractive systems. We model the static structure factor of these systems using effective pair interaction potentials composed of a long-range attraction and a shorter range repulsion. Our modeling of the static structure yields conditions for dynamically arrested states at larger volume fractions, which we find to agree with the experimentally observed dynamics.

  10. Effects of the heterogeneous landscape on a predator-prey system

    NASA Astrophysics Data System (ADS)

    Lee, Sang-Hee

    2010-01-01

    In order to understand how a heterogeneous landscape affects a predator-prey system, a spatially explicit lattice model consisting of predators, prey, grass, and landscape was constructed. The predators and preys randomly move on the lattice space and the grass grows in its neighboring site according to its growth probability. When predators and preys meet at the same site at the same time, a number of prey, equal to the number of predators are eaten. This rule was also applied to the relationship between the prey and grass. The predator (prey) could give birth to an offspring when it ate prey (grass), with a birth probability. When a predator or prey animal was initially introduced, or newly born, its health state was set at a given high value. This health state decreased by one with every time step. When the state of an animal decreased to less than zero, the animal died and was removed from the system. The heterogeneous landscape was characterized by parameter H, which controlled the heterogeneity according to the neutral model. The simulation results showed that H positively or negatively affected a predator’s survival, while its effect on prey and grass was less pronounced. The results can be understood by the disturbance of the balance between the prey and predator densities in the areas where the animals aggregated.

  11. A parameterized model for the evolution of isotopic heterogeneities in a convecting system. [for earth mantle

    NASA Technical Reports Server (NTRS)

    Richter, F. M.; Daly, S. F.; Nataf, H.-C.

    1982-01-01

    It is experimentally shown that, although steady convective flows are efficient means to heterogeneity within a single cell, they do not produce a dispersal of heterogeneous material over scales that are large by comparison to their depth, which requires that the flow be time-dependent on a time scale comparable to the overturn time. Convection in an internally heated layer does possess this property, and numerical solutions are presently used to study the way in which it disperses a set of neutrally bouyant particles initially confined to a small space. The derived concept of effective diffusivity is applied to the isotopic evolution of the Sm-Nd and Rb-Sr systems, with spatial variations generated by horizontal variations in degree of melting 1.8 billion years ago.

  12. Development of a Sox2 reporter system modeling cellular heterogeneity in glioma

    PubMed Central

    Stoltz, Kevin; Sinyuk, Maksim; Hale, James S.; Wu, Qiulian; Otvos, Balint; Walker, Kiera; Vasanji, Amit; Rich, Jeremy N.; Hjelmeland, Anita B.; Lathia, Justin D.

    2015-01-01

    Background Malignant gliomas are complex systems containing a number of factors that drive tumor initiation and progression, including genetic aberrations that lead to extensive cellular heterogeneity within the neoplastic compartment. Mouse models recapitulate these genetic aberrations, but readily observable heterogeneity remains challenging. Methods To interrogate cellular heterogeneity in mouse glioma models, we utilized a replication-competent avian sarcoma-leukosis virus long terminal repeat with splice acceptor/tumor virus A (RCAS-tva) system to generate spontaneous mouse gliomas that contained a Sox2-enhanced green fluorescent protein (EGFP) reporter. Glial fibrillary acidic protein-tva mice were crossed with Sox2–EGFP mice, and tumors were initiated that contained a subpopulation of Sox2–EGFP-high cells enriched for tumor-initiating cell properties such as self-renewal, multilineage differentiation potential, and perivascular localization. Results Following implantation into recipient mice, Sox2–EGFP-high cells generated tumors containing Sox2–EGFP-high and Sox2–EGFP-low cells. Kinomic analysis of Sox2–EGFP-high cells revealed activation of known glioma signaling pathways that are strongly correlated with patient survival including platelet-derived growth factor receptor beta, phosphoinositide-3 kinase, and vascular endothelial growth factor. Our functional analysis identified active feline sarcoma (Fes) signaling in Sox2–EGFP-high cells. Fes negatively correlated with glioma patient survival and was coexpressed with Sox2-positive cells in glioma xenografts and primary patient-derived tissue. Conclusions Our RCAS-tva/Sox2-EGFP model will empower closer examination of cellular heterogeneity and will be useful for identifying novel glioma pathways as well as testing preclinical treatment efficacy. PMID:25416826

  13. A feedback-trained autonomous control system for heterogeneous search and rescue applications

    NASA Astrophysics Data System (ADS)

    Straub, Jeremy

    2012-06-01

    Due to the environment in which operation occurs, earch and rescue (SAR) applications present a challenge to autonomous systems. A control technique for a heterogeneous multi-robot group is discussed. The proposed methodology is not fully autonomous; however, human operators are freed from most control tasks and allowed to focus on perception tasks while robots execute a collaborative search and identification plan. Robotic control combines a centralized dispatch and learning system (which continuously refines heuristics used for planning) with local autonomous task ordering (based on existing task priority and proximity and local conditions). This technique was tested in a SAR analogous (from a control perspective) environment.

  14. Modelling Napl Dissolution from Lens and Pools Under Varying Flowfields in Heterogeneous Subsurface Systems

    NASA Astrophysics Data System (ADS)

    Prakash, P.; Nambi, I. M.

    2011-12-01

    Non- Aqueous Phase Liquids (NAPLs) such as chlorinated organic solvents are major sources of groundwater contamination throughout the world. The non-uniform distribution of these contaminants as NAPL pools and residual NAPL zones introduce additional spatial heterogeneity in the hydrological parameters such as porosity and permeability. Bench scale dissolution studies were carried out and a conceptual contaminant transport model was developed to predict the downstream NAPL concentrations in aqueous phase. The dissolution studies were carried out in a bench scale 2-D sand tank reactor for multiple NAPL configurations and various initial NAPL saturations. A complex heterogeneous subsurface system mimicking NAPL as residuals, NAPL as lens and NAPL as pools was created by embedding more than one NAPL contaminated zone of coarse sand within a clean NAPL free zone of fine sand. Dissolved NAPL concentrations were measured along the downstream of NAPL source zone. A 2-D conceptual contaminant transport model was developed and validated which successfully accounts for NAPL interphase mass transfer limitation under varying flow fields in a saturated heterogeneous subsurface systems. The analysis of multiple lens experimental data revealed that initial NAPL saturations and relative permeability have significant effect in altering mass transfer characteristics which affects the efficacy of any remedial effort to decontaminate groundwater. Non equilibrium concentrations of NAPL were observed near the source zone during dissolution from high initial NAPL saturations, whereas tailing concentrations with steep decline from equilibrium state were seen at later times. The rate limited conditions occurred much earlier under heterogeneous soil conditions when compared to those observed by researchers under homogeneous soil conditions. This behavior was attributed to the large changes in aqueous permeability fields occurring with the progress of dissolution process. Mathematical

  15. Hydrothermal synthesis, crystal structure, and magnetic properties of Cs[(V[sub 2]O[sub 3])(HPO[sub 4])[sub 2](H[sub 2]O)], a mixed-valence vanadium (IV, V) hydrogen phosphate with a one-dimensional (-V[sup IV]-O-V[sup V]-O-) chain of corner-sharing VO[sub 6] octahedra

    SciTech Connect

    Haushalter, R.C. ); Wang, Z. Princeton Univ., Princeton, NJ ); Thompson, M.E. ); Zubieta, J. ); O'Connor, C.J. )

    1994-04-01

    The hydrothermal reaction of Cs[sub 4]V[sub 2]O[sub 7], V, H[sub 3]PO[sub 4], H[sub 2]O, and Bu[sub 4]NBr in the molar ratio 4.5:1:41:3150:1 at 200[degrees]C for 48 hr yielded the red-brown cesium vanadium phosphate Cs[(V[sub 2]O[sub 3])(HPO[sub 4])[sub 2](H[sub 2]O)], a mixed-valence V(IV, V) species. The structure contains corner-sharing vanadium octahedra and phosphorus tetrahedra with unusual 1-D (-V[sup IV]-O-V[sup v]-O-)[infinity] chains formed from VO[sub 6] octahedra sharing opposite corners. These chains are connected through tridentate bridging (HPO[sub 4])[sup 2[minus

  16. Solar fuels generation and molecular systems: is it homogeneous or heterogeneous catalysis?

    PubMed

    Artero, Vincent; Fontecave, Marc

    2013-03-21

    Catalysis is a key enabling technology for solar fuel generation. A number of catalytic systems, either molecular/homogeneous or solid/heterogeneous, have been developed during the last few decades for both the reductive and oxidative multi-electron reactions required for fuel production from water or CO(2) as renewable raw materials. While allowing for a fine tuning of the catalytic properties through ligand design, molecular approaches are frequently criticized because of the inherent fragility of the resulting catalysts, when exposed to extreme redox potentials. In a number of cases, it has been clearly established that the true catalytic species is heterogeneous in nature, arising from the transformation of the initial molecular species, which should rather be considered as a pre-catalyst. Whether such a situation is general or not is a matter of debate in the community. In this review, covering water oxidation and reduction catalysts, involving noble and non-noble metal ions, we limit our discussion to the cases in which this issue has been directly and properly addressed as well as those requiring more confirmation. The methodologies proposed for discriminating homogeneous and heterogeneous catalysis are inspired in part by those previously discussed by Finke in the case of homogeneous hydrogenation reaction in organometallic chemistry [J. A. Widegren and R. G. Finke, J. Mol. Catal. A, 2003, 198, 317-341].

  17. Modeling expected solute concentration in randomly heterogeneous flow systems with multicomponent reactions.

    PubMed

    Malmström, Maria E; Destouni, Georgia; Martinet, Philippe

    2004-05-01

    Many environmental problems require assessment of extensive reaction systems within natural subsurface flow systems exhibiting large physical and biogeochemical heterogeneity. We present an approach to couple stochastic advective-reactive modeling of physical solute transport (LaSAR) with the geochemical model PHREEQC for modeling solute concentrations in systems with variable flow velocity and multicomponent reactions. PHREEQC allows for general and flexible quantification of a multitude of linear and nonlinear geochemical processes, while LaSAR efficiently handles field-scale solute spreading in stochastic heterogeneous flow fields. The combined LaSAR-PHREEQC approach requires very modest computational efforts, thereby allowing a large number of reactive transport problems to be readily assessed and facilitating handling of quantifiable uncertainty in environmental model applications. Computational efficiency and explicit handling of field-scale dispersion without introduction of excessive fluid mixing that may impair model results are general advantages of the LaSAR compared with alternative solute transport modeling approaches. The LaSAR-PHREEQC approach is restricted to steady or unidirectional flow fields, and our specific application examples are limited to homogeneous reaction systems without local or transverse dispersion-diffusion, although these are not general methodological limitations. As a comprehensive application example, we simulate the spreading of acid mine drainage in a groundwater focusing on Zn2+ and including relevant, major-component geochemistry. Model results show that Zn2+ may be substantially attenuated by both sorption and precipitation, with flow heterogeneity greatly affecting expected solute concentrations downstream of the mine waste deposit in both cases. PMID:15180064

  18. Implementation of integrated heterogeneous electronic electrocardiography data into Maharaj Nakorn Chiang Mai Hospital Information System.

    PubMed

    Khumrin, Piyapong; Chumpoo, Pitupoom

    2016-03-01

    Electrocardiography is one of the most important non-invasive diagnostic tools for diagnosing coronary heart disease. The electrocardiography information system in Maharaj Nakorn Chiang Mai Hospital required a massive manual labor effort. In this article, we propose an approach toward the integration of heterogeneous electrocardiography data and the implementation of an integrated electrocardiography information system into the existing Hospital Information System. The system integrates different electrocardiography formats into a consistent electrocardiography rendering by using Java software. The interface acts as middleware to seamlessly integrate different electrocardiography formats. Instead of using a common electrocardiography protocol, we applied a central format based on Java classes for mapping different electrocardiography formats which contains a specific parser for each electrocardiography format to acquire the same information. Our observations showed that the new system improved the effectiveness of data management, work flow, and data quality; increased the availability of information; and finally improved quality of care.

  19. An optimum approximation of n-point correlation functions of random heterogeneous material systems

    SciTech Connect

    Baniassadi, M.; Garmestani, H.; Ahzi, S.; Remond, Y.

    2014-02-21

    An approximate solution for n-point correlation functions is developed in this study. In the approximate solution, weight functions are used to connect subsets of (n-1)-point correlation functions to estimate the full set of n-point correlation functions. In previous related studies, simple weight functions were introduced for the approximation of three and four-point correlation functions. In this work, the general framework of the weight functions is extended and derived to achieve optimum accuracy for approximate n-point correlation functions. Such approximation can be utilized to construct global n-point correlation functions for a system when there exist limited information about these functions in a subset of space. To verify its accuracy, the new formulation is used to approximate numerically three-point correlation functions from the set of two-point functions directly evaluated from a virtually generated isotropic heterogeneous microstructure representing a particulate composite system. Similarly, three-point functions are approximated for an anisotropic glass fiber/epoxy composite system and compared to their corresponding reference values calculated from an experimental dataset acquired by computational tomography. Results from both virtual and experimental studies confirm the accuracy of the new approximation. The new formulation can be utilized to attain a more accurate approximation to global n-point correlation functions for heterogeneous material systems with a hierarchy of length scales.

  20. Nanolithographic Fabrication and Heterogeneous Reaction Studies ofTwo-Dimensional Platinum Model Catalyst Systems

    SciTech Connect

    Contreras, Anthony Marshall

    2006-05-20

    In order to better understand the fundamental components that govern catalytic activity, two-dimensional model platinum nanocatalyst arrays have been designed and fabricated. These catalysts arrays are meant to model the interplay of the metal and support important to industrial heterogeneous catalytic reactions. Photolithography and sub-lithographic techniques such as electron beam lithography, size reduction lithography and nanoimprint lithography have been employed to create these platinum nanoarrays. Both in-situ and ex-situ surface science techniques and catalytic reaction measurements were used to correlate the structural parameters of the system to catalytic activity.

  1. Heterogeneity of the Peripheral Circadian Systems in Drosophila melanogaster: A Review.

    PubMed

    Ito, Chihiro; Tomioka, Kenji

    2016-01-01

    Circadian rhythms in organisms are involved in many aspects of metabolism, physiology, and behavior. In many animals, these rhythms are produced by the circadian system consisting of a central clock located in the brain and peripheral clocks in various peripheral tissues. The oscillatory machinery and entrainment mechanism of peripheral clocks vary between different tissues and organs. The relationship between the central and peripheral clocks is also tissue-dependent. Here we review the heterogeneous nature of peripheral circadian clocks in the fruit fly Drosophila melanogaster and their dependence on the central clock, and discuss their significance in the temporal organization of physiology in peripheral tissues/organs. PMID:26858652

  2. Finite-time consensus for heterogeneous multi-agent systems with mixed-order agents

    NASA Astrophysics Data System (ADS)

    Sun, Fenglan; Zhu, Wei

    2015-08-01

    This paper studies the finite-time consensus for heterogeneous multi-agent systems composed of mixed-order agents over fixed and switching topologies. The control protocol of each agent using local information is designed and the detailed analysis of the finite-time consensus for fixed and switching interaction topologies is presented. The design of the finite-time consensus protocol is based on graph theory, matrix theory, and LaSalle's invariance principle. Both theoretical studies and simulation results show the effectiveness of the proposed method and the correctness of the obtained theoretical results.

  3. Heterogeneity of the Peripheral Circadian Systems in Drosophila melanogaster: A Review

    PubMed Central

    Ito, Chihiro; Tomioka, Kenji

    2016-01-01

    Circadian rhythms in organisms are involved in many aspects of metabolism, physiology, and behavior. In many animals, these rhythms are produced by the circadian system consisting of a central clock located in the brain and peripheral clocks in various peripheral tissues. The oscillatory machinery and entrainment mechanism of peripheral clocks vary between different tissues and organs. The relationship between the central and peripheral clocks is also tissue-dependent. Here we review the heterogeneous nature of peripheral circadian clocks in the fruit fly Drosophila melanogaster and their dependence on the central clock, and discuss their significance in the temporal organization of physiology in peripheral tissues/organs. PMID:26858652

  4. Phenotypic plasticity of the maize root system in response to heterogeneous nitrogen availability.

    PubMed

    Yu, Peng; White, Philip J; Hochholdinger, Frank; Li, Chunjian

    2014-10-01

    Mineral nutrients are distributed in a non-uniform manner in the soil. Plasticity in root responses to the availability of mineral nutrients is believed to be important for optimizing nutrient acquisition. The response of root architecture to heterogeneous nutrient availability has been documented in various plant species, and the molecular mechanisms coordinating these responses have been investigated particularly in Arabidopsis, a model dicotyledonous plant. Recently, progress has been made in describing the phenotypic plasticity of root architecture in maize, a monocotyledonous crop. This article reviews aspects of phenotypic plasticity of maize root system architecture, with special emphasis on describing (1) the development of its complex root system; (2) phenotypic responses in root system architecture to heterogeneous N availability; (3) the importance of phenotypic plasticity for N acquisition; (4) different regulation of root growth and nutrients uptake by shoot; and (5) root traits in maize breeding. This knowledge will inform breeding strategies for root traits enabling more efficient acquisition of soil resources and synchronizing crop growth demand, root resource acquisition and fertilizer application during crop growing season, thereby maximizing crop yields and nutrient-use efficiency and minimizing environmental pollution. PMID:25143250

  5. BIOZON: a system for unification, management and analysis of heterogeneous biological data

    PubMed Central

    Birkland, Aaron; Yona, Golan

    2006-01-01

    Background Integration of heterogeneous data types is a challenging problem, especially in biology, where the number of databases and data types increase rapidly. Amongst the problems that one has to face are integrity, consistency, redundancy, connectivity, expressiveness and updatability. Description Here we present a system (Biozon) that addresses these problems, and offers biologists a new knowledge resource to navigate through and explore. Biozon unifies multiple biological databases consisting of a variety of data types (such as DNA sequences, proteins, interactions and cellular pathways). It is fundamentally different from previous efforts as it uses a single extensive and tightly connected graph schema wrapped with hierarchical ontology of documents and relations. Beyond warehousing existing data, Biozon computes and stores novel derived data, such as similarity relationships and functional predictions. The integration of similarity data allows propagation of knowledge through inference and fuzzy searches. Sophisticated methods of query that span multiple data types were implemented and first-of-a-kind biological ranking systems were explored and integrated. Conclusion The Biozon system is an extensive knowledge resource of heterogeneous biological data. Currently, it holds more than 100 million biological documents and 6.5 billion relations between them. The database is accessible through an advanced web interface that supports complex queries, "fuzzy" searches, data materialization and more, online at . PMID:16480510

  6. Analysis of application of Langmuir isotherm to heterogeneous systems: high-pressure conditions.

    PubMed

    Cordeiro, Cristian Nunes; da Rocha, Milton Silva; Faleiros, Antônio C; Iha, Koshun

    2005-06-15

    In this paper, an adsorption model that is based on the statistical mechanics approach was applied to study the saturation phenomena in adsorption to calculate the minimum pressure needed to attain the complete surface coverage on a physical adsorption. The fundamental integral equation, Theta(T)(Q)=integral N(Q)Theta(Q)dQ, for the calculation of the coverage degree of the surface was developed for an exponential distribution function, N(Q)=(m/RT)exp(-mQ/RT), and the representation of local adsorption sites is given by the Langmuir expression, Theta(Q)=b(0)C exp(Q/RT)/(1+b(0)C exp(Q/RT)). At high values of the pressure C, a solution of the fundamental integral equation was obtained by imposing the condition b(0)C>1. The expression for the saturation condition, b(0)C>m/(m+1), was obtained; that is, the saturation phenomenon is dependent on two parameters, correlated with the energetic heterogeneity and adsorption energy of the system. The pressure in the analysis of the cited expression shows that, for low m values (more heterogeneous systems), saturation is attained for b(0)C>m, while for m congruent with 1 (more homogeneous systems), the saturation is attained for b(0)C>0.5.

  7. Where should fine-resolution spatial heterogeneity be captured within Earth System Models?

    NASA Astrophysics Data System (ADS)

    Adam, J. C.; Hull, R.; Tague, C.; Reyes, J. J.; Liu, M.

    2015-12-01

    Land-atmosphere interactions impact the environment in many ways, such as through partially driving our climate system, and in changing the availability and usability of our natural resources. Earth System Models (EaSMs) are being used increasingly to explore these coupled dynamics from watershed to global scales. However, many EaSMs do not adequately represent landscape-scale spatial heterogeneity that influences land surface response, as relatively coarse resolution simulations are necessitated by computational limitations. Research is needed to understand which types of spatial heterogeneity, over which biomes and climate types, should be represented such that an EaSM accurately captures the aggregate land surface response to a changing climate. Spatial heterogeneity in a landscape arises due to differences in model forcings; in underlying soil, vegetation, and topographic properties that control moisture, energy and nutrient fluxes; and in land surface responses that arise due to spatially-organized connections. While our long-term goal is to understand how each of these sources should be represented in an EaSM, in this study we focus first on parameter heterogeneity. We apply the Regional Hydro-Ecological Simulation System (RHESSys), a distributed process-based model that was originally developed for catchment-scale applications. We explore the functional form of the hydrologic response of a RHESSys "patch" (a 200-400 m element with homogenous landscape parameters) to an invoked change. According to scale transition theory, a linear response makes it is possible to upscale (or aggregate) the model resolution without biasing the model response. We perform RHESSys simulations for more than 500 individual catchments within the Willamette and Yakima River basins in the Pacific Northwest region of the U.S. Each catchment was imposed with incremental perturbations of temperature and precipitation. The response curves for hydrologic variables such as

  8. Design of infrared signal processing system based on heterogeneous MPSoC

    NASA Astrophysics Data System (ADS)

    Zhang, Hao; Tang, Xinyi

    2015-02-01

    As one of the most significant parts in the development of the next generation infrared detection system, the infrared signal processing system requires the ability of real-time processing and high speed data transmission. A newly developed real-time signal processing system for infrared detecting based on the heterogeneous multiprocessor system on chip (MPSoC) is proposed in this paper. The device follows the architecture of Xilinx Zynq platform, integrating a feature rich dual-core ARM and Xilinx FPGA in a single chip, built on the 28nm high-k metal gate process technology. According to our design, the FPGA fabric portion retains all the programmable flexibility to drive the infrared detector and acquire data from ADC, with registers parallel operations to implement hardware acceleration. Furthermore, the FPGA fabric is connected to the ARM centered processor unit through multiple high performance interfaces, confirming high bandwidth communication and high speed data transmission between the two portions. Finally, the dual core ARM takes charge of the infrared signal processing system in general. One of the CPUs controls separate hardware modules and maintains the GUI for user interaction. The other responds to the dedicated system commands and external interrupts to update system parameters simultaneously. The integration of ARM and FPGA provides levels of performance that two-chip solutions cannot match due to their limited I/O bandwidth, loose coupling and power budgets. Experiments show that the architecture of heterogeneous MPSoC enhances the efficiency of memory controller and increases the speed of data transmission, approaching the theoretical value of the interfaces bandwidth.

  9. Development Of An Open System For Integration Of Heterogeneous Models For Flood Forecasting And Hazard Mitigation

    NASA Astrophysics Data System (ADS)

    Chang, W.; Tsai, W.; Lin, F.; Lin, S.; Lien, H.; Chung, T.; Huang, L.; Lee, K.; Chang, C.

    2008-12-01

    During a typhoon or a heavy storm event, using various forecasting models to predict rainfall intensity, and water level variation in rivers and flood situation in the urban area is able to reveal its capability technically. However, in practice, the following two causes tend to restrain the further application of these models as a decision support system (DSS) for the hazard mitigation. The first one is due to the difficulty of integration of heterogeneous models. One has to take into consideration the different using format of models, such as input files, output files, computational requirements, and so on. The second one is that the development of DSS requires, due to the heterogeneity of models and systems, a friendly user interface or platform to hide the complexity of various tools from users. It is expected that users can be governmental officials rather than professional experts, therefore the complicated interface of DSS is not acceptable. Based on the above considerations, in the present study, we develop an open system for integration of several simulation models for flood forecasting by adopting the FEWS (Flood Early Warning System) platform developed by WL | Delft Hydraulics. It allows us to link heterogeneous models effectively and provides suitable display modules. In addition, FEWS also has been adopted by Water Resource Agency (WRA), Taiwan as the standard operational system for river flooding management. That means this work can be much easily integrated with the use of practical cases. In the present study, based on FEWS platform, the basin rainfall-runoff model, SOBEK channel-routing model, and estuary tide forecasting model are linked and integrated through the physical connection of model initial and boundary definitions. The work flow of the integrated processes of models is shown in Fig. 1. This differs from the typical single model linking used in FEWS, which only aims at data exchange but without much physical consideration. So it really

  10. HER2 aberrations and heterogeneity in cancers of the digestive system: Implications for pathologists and gastroenterologists

    PubMed Central

    Fusco, Nicola; Bosari, Silvano

    2016-01-01

    Management of cancers of the digestive system has progressed rapidly into the molecular era. Despite the significant recent achievements in the diagnosis and treatment of these patients, the number of deaths for these tumors has currently plateaued. Many investigations have assessed the role of HER2 in tumors of the digestive system in both prognostic and therapeutic settings, with heterogeneous results. Novel testing and treatment guidelines are emerging, in particular in gastric and colorectal cancers. However, further advances are needed. In this review we provide a comprehensive overview of the current state-of-knowledge of HER2 alterations in the most common tumors of the digestive system and discuss the operational implications of HER2 testing. PMID:27672288

  11. Landscape heterogeneity shapes predation in a newly restored predator-prey system

    USGS Publications Warehouse

    Kauffman, M.J.; Varley, N.; Smith, D.W.; Stahler, D.R.; MacNulty, D.R.; Boyce, M.S.

    2007-01-01

    Because some native ungulates have lived without top predators for generations, it has been uncertain whether runaway predation would occur when predators are newly restored to these systems. We show that landscape features and vegetation, which influence predator detection and capture of prey, shape large-scale patterns of predation in a newly restored predator-prey system. We analysed the spatial distribution of wolf (Canis lupus) predation on elk (Cervus elaphus) on the Northern Range of Yellowstone National Park over 10 consecutive winters. The influence of wolf distribution on kill sites diminished over the course of this study, a result that was likely caused by territorial constraints on wolf distribution. In contrast, landscape factors strongly influenced kill sites, creating distinct hunting grounds and prey refugia. Elk in this newly restored predator-prey system should be able to mediate their risk of predation by movement and habitat selection across a heterogeneous risk landscape. ?? 2007 Blackwell Publishing Ltd/CNRS.

  12. Landscape heterogeneity shapes predation in a newly restored predator-prey system.

    PubMed

    Kauffman, Matthew J; Varley, Nathan; Smith, Douglas W; Stahler, Daniel R; MacNulty, Daniel R; Boyce, Mark S

    2007-08-01

    Because some native ungulates have lived without top predators for generations, it has been uncertain whether runaway predation would occur when predators are newly restored to these systems. We show that landscape features and vegetation, which influence predator detection and capture of prey, shape large-scale patterns of predation in a newly restored predator-prey system. We analysed the spatial distribution of wolf (Canis lupus) predation on elk (Cervus elaphus) on the Northern Range of Yellowstone National Park over 10 consecutive winters. The influence of wolf distribution on kill sites diminished over the course of this study, a result that was likely caused by territorial constraints on wolf distribution. In contrast, landscape factors strongly influenced kill sites, creating distinct hunting grounds and prey refugia. Elk in this newly restored predator-prey system should be able to mediate their risk of predation by movement and habitat selection across a heterogeneous risk landscape. PMID:17594424

  13. An energy-efficient underground localization system based on heterogeneous wireless networks.

    PubMed

    Yuan, Yazhou; Chen, Cailian; Guan, Xinping; Yang, Qiuling

    2015-05-26

    A precision positioning system with energy efficiency is of great necessity for guaranteeing personnel safety in underground mines. The location information of the miners' should be transmitted to the control center timely and reliably; therefore, a heterogeneous network with the backbone based on high speed Industrial Ethernet is deployed. Since the mobile wireless nodes are working in an irregular tunnel, a specific wireless propagation model cannot fit all situations. In this paper, an underground localization system is designed to enable the adaptation to kinds of harsh tunnel environments, but also to reduce the energy consumption and thus prolong the lifetime of the network. Three key techniques are developed and implemented to improve the system performance, including a step counting algorithm with accelerometers, a power control algorithm and an adaptive packets scheduling scheme. The simulation study and experimental results show the effectiveness of the proposed algorithms and the implementation.

  14. System of and method for transparent management of data objects in containers across distributed heterogenous resources

    DOEpatents

    Moore, Reagan W.; Rajasekar, Arcot; Wan, Michael Y.

    2004-01-13

    A system of and method for maintaining data objects in containers across a network of distributed heterogeneous resources in a manner which is transparent to a client. A client request pertaining to containers is resolved by querying meta data for the container, processing the request through one or more copies of the container maintained on the system, updating the meta data for the container to reflect any changes made to the container as a result processing the request, and, if a copy of the container has changed, changing the status of the copy to indicate dirty status or synchronizing the copy to one or more other copies that may be present on the system.

  15. HER2 aberrations and heterogeneity in cancers of the digestive system: Implications for pathologists and gastroenterologists

    PubMed Central

    Fusco, Nicola; Bosari, Silvano

    2016-01-01

    Management of cancers of the digestive system has progressed rapidly into the molecular era. Despite the significant recent achievements in the diagnosis and treatment of these patients, the number of deaths for these tumors has currently plateaued. Many investigations have assessed the role of HER2 in tumors of the digestive system in both prognostic and therapeutic settings, with heterogeneous results. Novel testing and treatment guidelines are emerging, in particular in gastric and colorectal cancers. However, further advances are needed. In this review we provide a comprehensive overview of the current state-of-knowledge of HER2 alterations in the most common tumors of the digestive system and discuss the operational implications of HER2 testing.

  16. System of and method for transparent management of data objects in containers across distributed heterogenous resources

    DOEpatents

    Moore, Reagan W.; Rajasekar, Arcot; Wan, Michael Y.

    2007-09-11

    A system of and method for maintaining data objects in containers across a network of distributed heterogeneous resources in a manner which is transparent to a client. A client request pertaining to containers is resolved by querying meta data for the container, processing the request through one or more copies of the container maintained on the system, updating the meta data for the container to reflect any changes made to the container as a result processing the re quest, and, if a copy of the container has changed, changing the status of the copy to indicate dirty status or synchronizing the copy to one or more other copies that may be present on the system.

  17. System of and method for transparent management of data objects in containers across distributed heterogenous resources

    DOEpatents

    Moore, Reagan W.; Rajasekar, Arcot; Wan, Michael Y.

    2010-09-21

    A system of and method for maintaining data objects in containers across a network of distributed heterogeneous resources in a manner which is transparent to a client. A client request pertaining to containers is resolved by querying meta data for the container, processing the request through one or more copies of the container maintained on the system, updating the meta data for the container to reflect any changes made to the container as a result processing the request, and, if a copy of the container has changed, changing the status of the copy to indicate dirty status or synchronizing the copy to one or more other copies that may be present on the system.

  18. HER2 aberrations and heterogeneity in cancers of the digestive system: Implications for pathologists and gastroenterologists.

    PubMed

    Fusco, Nicola; Bosari, Silvano

    2016-09-21

    Management of cancers of the digestive system has progressed rapidly into the molecular era. Despite the significant recent achievements in the diagnosis and treatment of these patients, the number of deaths for these tumors has currently plateaued. Many investigations have assessed the role of HER2 in tumors of the digestive system in both prognostic and therapeutic settings, with heterogeneous results. Novel testing and treatment guidelines are emerging, in particular in gastric and colorectal cancers. However, further advances are needed. In this review we provide a comprehensive overview of the current state-of-knowledge of HER2 alterations in the most common tumors of the digestive system and discuss the operational implications of HER2 testing. PMID:27672288

  19. On the integration of the baroreflex control mechanism in a heterogeneous model of the cardiovascular system.

    PubMed

    Blanco, P J; Trenhago, P R; Fernandes, L G; Feijóo, R A

    2012-04-01

    The aim of the present work is to describe the integration of a mathematical model for the baroreceptor reflex mechanism to provide regulatory action into a dimensionally heterogeneous (3D-1D-0D) closed-loop model of the cardiovascular system. Such heterogeneous model comprises a 1D description of the arterial tree, a 0D network for the venous, cardiac and pulmonary circulations and 3D patient-specific geometries for vascular districts of interest. Thus, the detailed topological description of the arterial network allows us to perform vasomotor control actions in a differentiated way, while gaining insight about the effects of the baroreflex regulation over hemodynamic quantities of interest throughout the entire network. Two examples of application are presented. Firstly, we simulate the hemorrhage in the abdominal aorta artery and analyze the action of the baroreflex over the system. Secondly, the self-regulated closed-loop model is applied to study the influence of the control action in the hemodynamic environment that determines the blood flow pattern in a cerebral aneurism in the presence of a regurgitating aortic valve. PMID:25365656

  20. Characterizing heterogeneity in children with and without ADHD based on reward system connectivity.

    PubMed

    Costa Dias, Taciana G; Iyer, Swathi P; Carpenter, Samuel D; Cary, Robert P; Wilson, Vanessa B; Mitchell, Suzanne H; Nigg, Joel T; Fair, Damien A

    2015-02-01

    One potential obstacle limiting our ability to clarify ADHD etiology is the heterogeneity within the disorder, as well as in typical samples. In this study, we utilized a community detection approach on 106 children with and without ADHD (aged 7-12 years), in order to identify potential subgroups of participants based on the connectivity of the reward system. Children with ADHD were compared to typically developing children within each identified community, aiming to find the community-specific ADHD characteristics. Furthermore, to assess how the organization in subgroups relates to behavior, we evaluated delay-discounting gradient and impulsivity-related temperament traits within each community. We found that discrete subgroups were identified that characterized distinct connectivity profiles in the reward system. Importantly, which connections were atypical in ADHD relative to the control children were specific to the community membership. Our findings showed that children with ADHD and typically developing children could be classified into distinct subgroups according to brain functional connectivity. Results also suggested that the differentiation in "functional" subgroups is related to specific behavioral characteristics, in this case impulsivity. Thus, combining neuroimaging data and community detection might be a valuable approach to elucidate heterogeneity in ADHD etiology and examine ADHD neurobiology.

  1. Vivaldi: A Domain-Specific Language for Volume Processing and Visualization on Distributed Heterogeneous Systems.

    PubMed

    Choi, Hyungsuk; Choi, Woohyuk; Quan, Tran Minh; Hildebrand, David G C; Pfister, Hanspeter; Jeong, Won-Ki

    2014-12-01

    As the size of image data from microscopes and telescopes increases, the need for high-throughput processing and visualization of large volumetric data has become more pressing. At the same time, many-core processors and GPU accelerators are commonplace, making high-performance distributed heterogeneous computing systems affordable. However, effectively utilizing GPU clusters is difficult for novice programmers, and even experienced programmers often fail to fully leverage the computing power of new parallel architectures due to their steep learning curve and programming complexity. In this paper, we propose Vivaldi, a new domain-specific language for volume processing and visualization on distributed heterogeneous computing systems. Vivaldi's Python-like grammar and parallel processing abstractions provide flexible programming tools for non-experts to easily write high-performance parallel computing code. Vivaldi provides commonly used functions and numerical operators for customized visualization and high-throughput image processing applications. We demonstrate the performance and usability of Vivaldi on several examples ranging from volume rendering to image segmentation. PMID:26356955

  2. High bee and wasp diversity in a heterogeneous tropical farming system compared to protected forest.

    PubMed

    Schüepp, Christof; Rittiner, Sarah; Entling, Martin H

    2012-01-01

    It is a globally important challenge to meet increasing demands for resources and, at the same time, protect biodiversity and ecosystem services. Farming is usually regarded as a major threat to biodiversity due to its expansion into natural areas. We compared biodiversity of bees and wasps between heterogeneous small-scale farming areas and protected forest in northern coastal Belize, Central America. Malaise traps operated for three months during the transition from wet to dry season. Farming areas consisted of a mosaic of mixed crop types, open habitat, secondary forest, and agroforestry. Mean species richness per site (alpha diversity), as well as spatial and temporal community variation (beta diversity) of bees and wasps were equal or higher in farming areas compared to protected forest. The higher species richness and community variation in farmland was due to additional species that did not occur in the forest, whereas most species trapped in forest were also found in farming areas. The overall regional species richness (gamma diversity) increased by 70% with the inclusion of farming areas. Our results suggest that small-scale farming systems adjacent to protected forest may not only conserve, but even favour, biodiversity of some taxonomic groups. We can, however, not exclude possible declines of bee and wasp diversity in more intensified farmland or in landscapes completely covered by heterogeneous farming systems.

  3. Hot news recommendation system from heterogeneous websites based on bayesian model.

    PubMed

    Xia, Zhengyou; Xu, Shengwu; Liu, Ningzhong; Zhao, Zhengkang

    2014-01-01

    The most current news recommendations are suitable for news which comes from a single news website, not for news from different heterogeneous news websites. Previous researches about news recommender systems based on different strategies have been proposed to provide news personalization services for online news readers. However, little research work has been reported on utilizing hundreds of heterogeneous news websites to provide top hot news services for group customers (e.g., government staffs). In this paper, we propose a hot news recommendation model based on Bayesian model, which is from hundreds of different news websites. In the model, we determine whether the news is hot news by calculating the joint probability of the news. We evaluate and compare our proposed recommendation model with the results of human experts on the real data sets. Experimental results demonstrate the reliability and effectiveness of our method. We also implement this model in hot news recommendation system of Hangzhou city government in year 2013, which achieves very good results.

  4. Geometrical Description of Contact Line Fluctuations in Heterogeneous Systems with Controlled Wettability.

    PubMed

    Araujo; Araujo

    2000-09-01

    The understanding of contact line fluctuations in heterogeneous systems of controlled wettability is relevant to many industrial processes. Despite its importance, it is poorly understood. Here, we present results on an experimental study of fluid displacement on modified Hele-Shaw cells with surface defects as heterogeneities. The system wettability is controlled by defect surface coverage. Three different surface coverage regimes were studied. For each one, the morphology and deformation energy of the displacement front is determined. The width front is described in terms of two exponents, the roughness exponent (alpha) and the one that describes its growth (beta). In all cases, it is found that the width increases logarithmically in time up to a characteristic value, where a crossover to a saturation behavior is observed. The crossover time is a function of the surface coverage. For low coverage 0.51

  5. Vivaldi: A Domain-Specific Language for Volume Processing and Visualization on Distributed Heterogeneous Systems.

    PubMed

    Choi, Hyungsuk; Choi, Woohyuk; Quan, Tran Minh; Hildebrand, David G C; Pfister, Hanspeter; Jeong, Won-Ki

    2014-12-01

    As the size of image data from microscopes and telescopes increases, the need for high-throughput processing and visualization of large volumetric data has become more pressing. At the same time, many-core processors and GPU accelerators are commonplace, making high-performance distributed heterogeneous computing systems affordable. However, effectively utilizing GPU clusters is difficult for novice programmers, and even experienced programmers often fail to fully leverage the computing power of new parallel architectures due to their steep learning curve and programming complexity. In this paper, we propose Vivaldi, a new domain-specific language for volume processing and visualization on distributed heterogeneous computing systems. Vivaldi's Python-like grammar and parallel processing abstractions provide flexible programming tools for non-experts to easily write high-performance parallel computing code. Vivaldi provides commonly used functions and numerical operators for customized visualization and high-throughput image processing applications. We demonstrate the performance and usability of Vivaldi on several examples ranging from volume rendering to image segmentation.

  6. An event-based model of braided river system aquifers heterogeneity based on Multiple Points Statistics

    NASA Astrophysics Data System (ADS)

    Renard, P.; Pirot, G.

    2012-12-01

    Braided-rivers are common in mountainous regions like the Swiss Alps. These dynamic systems generate highly heterogeneous deposits and form an important part of alluvial aquifers which are tapped for agriculture and drinking water supply. In this presentation, we propose to integrate large scale and high resolution LIDAR data in a pseudo genetic approach embedding Multiple Points Statistics (MPS) to model the heterogeneity of such aquifers. A way to build 3D sedimentary models is to use descriptive methods, which translate data into conceptual facies models but do not offer uncertainty quantification. Another possibility is the use of stochastic models but most of them do not include strong geological knowledge and their degree of realism can be rather weak. Another approach is to use process-based methods. In this work, we imitate the processes occurring during flood events, by building successive topographies with the Direct Sampling (DS) multiple point statistics algorithm. Each successive topography is conditioned by the previous one. All those steps are constrained by a series of LIDAR data sets allowing to train the algorithm. This is different from classical MPS models, since we do not directly use MPS to model the lithofacies directly, but instead to simulate the processes that lead to the heterogeneity in order to ensure that higher statistics that can be inferred from field data are accurately reproduced. The use of the DS is motivated by the fact that it an MPS technique allowing to co-simulate continuous variables. It is easy to condition to field data and offers a high degree of realism in the simulations. The underlying erosion-deposition process leaves some records of each event in the form of remaining layers, which are populated with facies of different granulometry, according to some predefined rules function of the geobody's shape and dimensions. Input parameters allow controlling the aggradation/degradation intensity.

  7. Evaluating the use of sub-tile Bulk Averaged inputs to simulate evapotranspiration within Heterogeneous Land-Atmosphere Systems

    NASA Astrophysics Data System (ADS)

    Chen, Qiting; Jia, Li; Hutjes, Ronald

    2016-04-01

    Evapotranspiration plays a crucial role in the regional water and energy balance and often takes place within heterogeneous land-atmosphere systems. Heterogeneity usually appears in the resolvable elements in Land Surface Models (LSMs). Typically, Land surface modelling to simulate evapotranspiration tends to oversimplify the sub-Tile heterogeneity of a Land-atmosphere parameter by a single representative value. This paper evaluates the inaccuracy of LSMs resulting from inaccurately representing the heterogeneity within resolvable elements by a bulk average value. In a synthetic experiment, seven Probability Density Functions (PDFs) were used to simulate the different scenarios of heterogeneity of Leaf Area Index (LAI) and top Soil Moisture (SM). Evapotranspiration estimates based on bulk averaged LAI and SM status were compared with the one obtained by the real distributed LAI and SM. Their difference is due to the combined effect of heterogeneities in LAI and SM, and the nonlinear processes in the LSMs. Besides the synthetic numerical experiment, we also tested the reliability of the bulk average scheme in a real world case for the Heihe river basin, northwest of China, to further demonstrate the importance of accounting for sub-Tile heterogeneity in evapotranspiration estimates and its implications for the regional and irrigation water management.

  8. Metaheuristic based scheduling meta-tasks in distributed heterogeneous computing systems.

    PubMed

    Izakian, Hesam; Abraham, Ajith; Snášel, Václav

    2009-01-01

    Scheduling is a key problem in distributed heterogeneous computing systems in order to benefit from the large computing capacity of such systems and is an NP-complete problem. In this paper, we present a metaheuristic technique, namely the Particle Swarm Optimization (PSO) algorithm, for this problem. PSO is a population-based search algorithm based on the simulation of the social behavior of bird flocking and fish schooling. Particles fly in problem search space to find optimal or near-optimal solutions. The scheduler aims at minimizing makespan, which is the time when finishes the latest task. Experimental studies show that the proposed method is more efficient and surpasses those of reported PSO and GA approaches for this problem.

  9. Synchronised output regulation of leader-following heterogeneous networked systems via error feedback

    NASA Astrophysics Data System (ADS)

    Li, Yanjun; Wang, Xuejie; Xiang, Ji; Wei, Wei

    2016-03-01

    A dynamic error feedback controller is presented for the synchronised output regulation (SOR) of leader-following heterogeneous linear networked systems. The nodes in the networked systems are divided into two kinds: the leader node accessible to the regulated error and the following nodes inaccessible to the regulated error but accessible to the relative output errors with respect to their neighbouring nodes. By using the small-gain theorem, a sufficient criterion for the SOR problem is developed for more general networks. This criterion can be regarded as imposing an additional H∞ constraint on the classical output regulation problem. The synthesis problem is then addressed by means of linear matrix inequality technique. The efficacy of the analytic results is illustrated by simulation examples.

  10. Heterogeneity of Systemic Oxidative Stress Profiles in COPD: A Potential Role of Gender

    PubMed Central

    Maury, Jonathan; Gouzi, Farés; De Rigal, Philippe; Heraud, Nelly; Pincemail, Joël; Molinari, Nicolas; Pomiès, Pascal; Laoudj-Chenivesse, Dalila; Mercier, Jacques; Préfaut, Christian; Hayot, Maurice

    2015-01-01

    Oxidative stress (OS) plays a key role in the muscle impairment and exercise capacity of COPD patients. However, the literature reveals that systemic OS markers show great heterogeneity, which may hinder the prescription of effective antioxidant supplementation. This study therefore aimed to identify OS markers imbalance of COPD patients, relative to validated normal reference values, and to investigate the possibility of systemic OS profiles. We measured systemic enzymatic/nonenzymatic antioxidant and lipid peroxidation (LP) levels in 54 stable COPD patients referred for a rehabilitation program. The main systemic antioxidant deficits in these patients concerned vitamins and trace elements. Fully 89% of the COPD patients showed a systemic antioxidant imbalance which may have caused the elevated systemic LP levels in 69% of them. Interestingly, two patient profiles (clusters 3 and 4) had a more elevated increase in LP combined with increased copper and/or decreased vitamin C, GSH, and GPx. Further analysis revealed that the systemic LP level was higher in COPD women and associated with exercise capacity. Our present data therefore support future supplementations with antioxidant vitamins and trace elements to improve exercise capacity, but COPD patients will probably show different positive responses. PMID:26167238

  11. Polypyrrole-functionalized ruthenium carbene catalysts as efficient heterogeneous systems for olefin epoxidation.

    PubMed

    Dakkach, Mohamed; Fontrodona, Xavier; Parella, Teodor; Atlamsani, Ahmed; Romero, Isabel; Rodríguez, Montserrat

    2014-07-14

    New Ru complexes containing the bpea-pyr ligand (bpea-pyr stands for N,N-bis(pyridin-2-ylmethyl)-3-(1H-pyrrol-1-yl)propan-1-amine), with the formula [RuCl2(bpea-pyr)(dmso)] (isomeric complexes 2a and 2b) or [Ru(CN-Me)(bpea-pyr)X)](n+) (CN-Me = 3-methyl-1-(pyridin-2-yl)-1H-imidazol-3-ium-2-ide; X = Cl, 3, or X = H2O, 4), have been prepared and fully characterized. Complexes 3 and 4 have been anchored onto an electrode surface through electropolymerization of the attached pyrrole group, yielding stable polypyrrole films. The electrochemical behaviour of 4, which displays a bielectronic Ru(IV/II) redox pair in solution, is dramatically affected by the electropolymerization process leading to the occurrence of two monoelectronic Ru(IV/III) and Ru(III/II) redox pairs in the heterogeneous system. A carbon felt modified electrode containing complex 4 (C-felt/poly-4) has been evaluated as a heterogeneous catalyst in the epoxidation of various olefin substrates using PhI(OAc)2 as an oxidant, displaying TON values of several thousands in all cases and good selectivity for the epoxide product.

  12. Effects of diffusion on total biomass in heterogeneous continuous and discrete-patch systems

    USGS Publications Warehouse

    DeAngelis, Don; Ming Ni, Wei; Zhang, Bo

    2016-01-01

    Theoretical models of populations on a system of two connected patches previously have shown that when the two patches differ in maximum growth rate and carrying capacity, and in the limit of high diffusion, conditions exist for which the total population size at equilibrium exceeds that of the ideal free distribution, which predicts that the total population would equal the total carrying capacity of the two patches. However, this result has only been shown for the Pearl-Verhulst growth function on two patches and for a single-parameter growth function in continuous space. Here, we provide a general criterion for total population size to exceed total carrying capacity for three commonly used population growth rates for both heterogeneous continuous and multi-patch heterogeneous landscapes with high population diffusion. We show that a sufficient condition for this situation is that there is a convex positive relationship between the maximum growth rate and the parameter that, by itself or together with the maximum growth rate, determines the carrying capacity, as both vary across a spatial region. This relationship occurs in some biological populations, though not in others, so the result has ecological implications.

  13. Barium and Neodymium Isotope Heterogeneities in Early Solar System Materials: Applications to Planetary Reservoir Models

    NASA Astrophysics Data System (ADS)

    Ranen, M. C.; Jacobsen, S. B.

    2005-12-01

    Heavy element isotopic heterogeneities in early Solar System materials may exist as a result of both incomplete mixing of pre-solar nucleosynthetic components in the Solar Nebula leading to different ratios of p-, r- and s-process isotopes in bulk planetary materials as well as heterogeneities caused by the decay of now extinct nuclides. Boyet and Carlson (2005) reported a difference in 142Nd/144Nd between Earths mantle and chondrites of about 20-30 ppm. Assuming that this difference was due to decay of 146Sm and that the Earth and chondrites formed with identical 146Sm/144Sm they inferred the formation of a deep enriched silicate layer (D'' ?) in the Earth that formed within the first 30 Myr of Solar System history. We have obtained a similar difference in 142Nd/144Nd between Earth and chondrites. However, we are now testing their interpretation with Ba isotope measurements of various chondrites. Barium is an ideal element for testing the origin of small isotopic anomalies because it has two isotopes (134 and 136) derived only from the s-process as well as three isotopes (135,137 and 138) derived from both the r- and s-process with 135Ba possibly having a contribution from the decay of now extinct 135Cs. Six chondrites: Allende (CV3), Peace River (L6), Murchison (CM2), Grady (H3.7), Guarena (H6), and Bruderheim (L6) were measured for Ba isotopic composition with a new generation TIMS instrument (a GV ISOPROBE-T). A terrestrial andesite, AGV-1, was also processed for use as our reference standard. Preliminary results indicate widespread heterogeneity in the fractionation corrected 137Ba/136Ba ratio between different meteorites and our terrestrial standard, as high as 25 ppm. Smaller anomalies are also seen in 134Ba/136Ba. These anomalies are likely caused by slight differences in the mixing proportions of r- and s-process Ba in Earth and chondrites. This calls into question whether or not the differences seen in 142Nd/144Nd are truly caused by early differentiation

  14. Mobility Controlled Flooding (MCF) Technology for Enhanced Sweeping and NAPL Remediation in Heterogeneous Systems

    NASA Astrophysics Data System (ADS)

    Zhong, L.; Oostrom, M.; Wietsma, T.

    2005-12-01

    Heterogeneity is often encountered in subsurface contamination characterization and remediation. Low-permeability zones are bypassed when remedial fluid is injected into heterogeneous systems. The contaminant in the bypassed areas is therefore untouched by the remedial fluid, which can prolong the remediation operations significantly. Methods of forcing fluids into low-permeability flow paths have been developed and widely implemented to solve the heterogeneity-induced bypassing problem encountered during oil recovery in the petroleum industry over the past 40 years. Since the intent of the petroleum reservoir engineers is to control the mobility of the injected fluid in the high-permeable zones so that the fluid can be pushed through the low-permeable zones to contact and mobilize the remaining oil in these zones, this method are referred as mobility controlled flooding (MCF) technology in the petroleum engineering literature. Two methods of mobility control have been developed. One method is to use a water-soluble polymer to increase the viscosity of the injectate so that the in situ pore pressure is raised, and cross-flow between layers with different permeability occurs. The other method is to use surfactant-foam flood to generate foam in high permeable zones in situ; therefore, the injected fluid is forced into the low-permeable areas. A water-soluble polymer, xanthan gum, and surfactant MA-80 was used to formulate MCF remedial fluids to remediate nonaqueous phase liquid (NAPL) contaminated heterogonous systems in two-dimensional (2-D) flow-cell (40 by 50 by 5 cm) experiments. It was demonstrated that the MCF technology is capable of sweeping the low-permeability flow paths. The bypassing of low-permeable zones was significantly reduced. The removal of NAPL trapped in the low-perm zones was remarkable enhanced attributed to more efficient NAPL mobilization. The results also indicate that the MCF technology is able to manage the fluid density effects. The

  15. Oligodendrocyte heterogeneity in the mouse juvenile and adult central nervous system.

    PubMed

    Marques, Sueli; Zeisel, Amit; Codeluppi, Simone; van Bruggen, David; Mendanha Falcão, Ana; Xiao, Lin; Li, Huiliang; Häring, Martin; Hochgerner, Hannah; Romanov, Roman A; Gyllborg, Daniel; Muñoz-Manchado, Ana B; La Manno, Gioele; Lönnerberg, Peter; Floriddia, Elisa M; Rezayee, Fatemah; Ernfors, Patrik; Arenas, Ernest; Hjerling-Leffler, Jens; Harkany, Tibor; Richardson, William D; Linnarsson, Sten; Castelo-Branco, Gonçalo

    2016-06-10

    Oligodendrocytes have been considered as a functionally homogeneous population in the central nervous system (CNS). We performed single-cell RNA sequencing on 5072 cells of the oligodendrocyte lineage from 10 regions of the mouse juvenile and adult CNS. Thirteen distinct populations were identified, 12 of which represent a continuum from Pdgfra(+) oligodendrocyte precursor cells (OPCs) to distinct mature oligodendrocytes. Initial stages of differentiation were similar across the juvenile CNS, whereas subsets of mature oligodendrocytes were enriched in specific regions in the adult brain. Newly formed oligodendrocytes were detected in the adult CNS and were responsive to complex motor learning. A second Pdgfra(+) population, distinct from OPCs, was found along vessels. Our study reveals the dynamics of oligodendrocyte differentiation and maturation, uncoupling them at a transcriptional level and highlighting oligodendrocyte heterogeneity in the CNS. PMID:27284195

  16. Calorimetry of heterogeneous systems: H+ binding to TiO2 in NaCl

    USGS Publications Warehouse

    Mehr, S.R.; Eatough, D.J.; Hansen, L.D.; Lewis, E.A.; Davis, J.A.

    1989-01-01

    A simultaneous calorimetric and potentiometric technique has been developed for measuring the thermodynamics of proton binding to mineral oxides in the presence of a supporting electrolyte. Modifications made to a commercial titration calorimeter to add a combination pH electrode and maintain an inert atmosphere in the calorimeter reaction vessel are described. A procedure to calibrate potentiometric measurements in heterogeneous systems to correct for the suspension effect on pH is given. The enthalpy change for proton dissociation from TiO2 in aqueous suspension as a function of pH is reported for 0.01, 0.1, and 0.5 M NaCl. The enthalpy change for proton dissociation is endothermic, ranging from 10.5 ?? 3.8 to 45.0 ?? 3.8 kJ mol-1 over the pH range from 4 to 10. ?? 1989.

  17. Oligodendrocyte heterogeneity in the mouse juvenile and adult central nervous system.

    PubMed

    Marques, Sueli; Zeisel, Amit; Codeluppi, Simone; van Bruggen, David; Mendanha Falcão, Ana; Xiao, Lin; Li, Huiliang; Häring, Martin; Hochgerner, Hannah; Romanov, Roman A; Gyllborg, Daniel; Muñoz-Manchado, Ana B; La Manno, Gioele; Lönnerberg, Peter; Floriddia, Elisa M; Rezayee, Fatemah; Ernfors, Patrik; Arenas, Ernest; Hjerling-Leffler, Jens; Harkany, Tibor; Richardson, William D; Linnarsson, Sten; Castelo-Branco, Gonçalo

    2016-06-10

    Oligodendrocytes have been considered as a functionally homogeneous population in the central nervous system (CNS). We performed single-cell RNA sequencing on 5072 cells of the oligodendrocyte lineage from 10 regions of the mouse juvenile and adult CNS. Thirteen distinct populations were identified, 12 of which represent a continuum from Pdgfra(+) oligodendrocyte precursor cells (OPCs) to distinct mature oligodendrocytes. Initial stages of differentiation were similar across the juvenile CNS, whereas subsets of mature oligodendrocytes were enriched in specific regions in the adult brain. Newly formed oligodendrocytes were detected in the adult CNS and were responsive to complex motor learning. A second Pdgfra(+) population, distinct from OPCs, was found along vessels. Our study reveals the dynamics of oligodendrocyte differentiation and maturation, uncoupling them at a transcriptional level and highlighting oligodendrocyte heterogeneity in the CNS.

  18. Impacts of SOC on car-following behavior and travel time in the heterogeneous traffic system

    NASA Astrophysics Data System (ADS)

    Tang, Tie-Qiao; Xu, Ke-Wei; Yang, Shi-Chun; Ding, Chuan

    2016-01-01

    Since the SOC (state of charge) of the battery of each electric vehicle directly determines whether the battery should be charged/swapped, the SOC may affect the electric vehicle's driving behavior. In this paper, we introduce the SOC of battery into the electric vehicle's driving behavior model and propose a car-following model for electric vehicles, and then use the proposed model to study the effects of the SOC of battery and battery swap on each vehicle's driving behavior in the heterogeneous traffic system consisting of traditional vehicles and electric vehicles. The numerical results show that the proposed model can reproduce some complex traffic phenomena resulted by the SOC of battery and battery swap and that the influences on each vehicle's driving behavior are directly related to the initial traffic state, the electric vehicle's proportion, and the SOC of battery.

  19. X-ray and synchrotron investigations of heterogeneous systems based on multiwalled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Sivkov, V. N.; Ob"edkov, A. M.; Petrova, O. V.; Nekipelov, S. V.; Kremlev, K. V.; Kaverin, B. S.; Semenov, N. M.; Gusev, S. A.

    2015-01-01

    This paper presents the results of a complex investigation of heterogeneous systems based on multiwalled carbon nanotubes with the outer surfaces covered by iron oxide (Fe3O4) nanocoatings deposited using iron pentacarbonyl as a precursor. Investigations were performed by the methods of electron microscopy, X-ray diffractometry, and ultrasoft X-ray spectroscopy with synchrotron radiation. It was established that the formed thin coatings are continuous and nonuniform in thickness. It was shown that good adhesion of iron oxide on the multiwalled carbon nanotube surface is provided by the formation of epoxy and double carbon-oxygen bonds; in this case, the outer graphene layer of nanotubes is not destroyed and retains the hexagonal structure.

  20. Heterogeneous reactivity effects in medium- and high-enriched uranium metal-water systems

    SciTech Connect

    Lichtenwalter, J.J.

    1997-07-01

    The effect of heterogeneity on reactivity of low-, medium-, and high-enriched, water-moderated uranium metal systems has been examined for various hydrogen-to-fissile (H/X) ratios using the CSAS1X sequence in SCALE and MCNP. For the calculations, an infinite array of close-packed unit cells was modeled which consisted of centered uranium metal spheres surrounded by water. The enrichments used correspond to the average enrichments of fragmented fuel plates in three proposed waste shipments from Oak Ridge National Laboratory. The analysis performed to obtain peak reactivity for each enrichment as a function of particle size and H/X ratio led to the development of the topic discussed in this paper.

  1. Geostatistical Simulation of Hydrofacies Heterogeneity of the West Thessaly Aquifer Systems in Greece

    SciTech Connect

    Modis, K. Sideri, D.

    2013-06-15

    Integrating geological properties, such as relative positions and proportions of different hydrofacies, is of highest importance in order to render realistic geological patterns. Sequential indicator simulation (SIS) and Plurigaussian simulation (PS) are alternative methods for conceptual and deterministic modeling for the characterization of hydrofacies distribution. In this work, we studied the spatial differentiation of hydrofacies in the alluvial aquifer system of West Thessaly basin in Greece. For this, we applied both SIS and PS techniques to an extensive set of borehole data from that basin. Histograms of model versus experimental hydrofacies proportions and indicative cross sections were plotted in order to validate the results. The PS technique was shown to be more effective in reproducing the spatial characteristics of the different hydrofacies and their distribution across the study area. In addition, the permeability differentiations reflected in the PS model are in accordance to known heterogeneities of the aquifer capacity.

  2. Simulation of Charged Systems in Heterogeneous Dielectric Media via a True Energy Functional

    NASA Astrophysics Data System (ADS)

    Jadhao, Vikram; Solis, Francisco J.; de la Cruz, Monica Olvera

    2012-11-01

    For charged systems in heterogeneous dielectric media, a key obstacle for molecular dynamics (MD) simulations is the need to solve the Poisson equation in the media. This obstacle can be bypassed using MD methods that treat the local polarization charge density as a dynamic variable, but such approaches require access to a true free energy functional, one that evaluates to the equilibrium electrostatic energy at its minimum. In this Letter, we derive the needed functional. As an application, we develop a Car-Parrinello MD method for the simulation of free charges present near a spherical emulsion droplet separating two immiscible liquids with different dielectric constants. Our results show the presence of nonmonotonic ionic profiles in the dielectric with a lower dielectric constant.

  3. Heterogeneous Multi-Robot System for Mapping Environmental Variables of Greenhouses.

    PubMed

    Roldán, Juan Jesús; Garcia-Aunon, Pablo; Garzón, Mario; de León, Jorge; Del Cerro, Jaime; Barrientos, Antonio

    2016-01-01

    The productivity of greenhouses highly depends on the environmental conditions of crops, such as temperature and humidity. The control and monitoring might need large sensor networks, and as a consequence, mobile sensory systems might be a more suitable solution. This paper describes the application of a heterogeneous robot team to monitor environmental variables of greenhouses. The multi-robot system includes both ground and aerial vehicles, looking to provide flexibility and improve performance. The multi-robot sensory system measures the temperature, humidity, luminosity and carbon dioxide concentration in the ground and at different heights. Nevertheless, these measurements can be complemented with other ones (e.g., the concentration of various gases or images of crops) without a considerable effort. Additionally, this work addresses some relevant challenges of multi-robot sensory systems, such as the mission planning and task allocation, the guidance, navigation and control of robots in greenhouses and the coordination among ground and aerial vehicles. This work has an eminently practical approach, and therefore, the system has been extensively tested both in simulations and field experiments. PMID:27376297

  4. Heterogeneous Multi-Robot System for Mapping Environmental Variables of Greenhouses

    PubMed Central

    Roldán, Juan Jesús; Garcia-Aunon, Pablo; Garzón, Mario; de León, Jorge; del Cerro, Jaime; Barrientos, Antonio

    2016-01-01

    The productivity of greenhouses highly depends on the environmental conditions of crops, such as temperature and humidity. The control and monitoring might need large sensor networks, and as a consequence, mobile sensory systems might be a more suitable solution. This paper describes the application of a heterogeneous robot team to monitor environmental variables of greenhouses. The multi-robot system includes both ground and aerial vehicles, looking to provide flexibility and improve performance. The multi-robot sensory system measures the temperature, humidity, luminosity and carbon dioxide concentration in the ground and at different heights. Nevertheless, these measurements can be complemented with other ones (e.g., the concentration of various gases or images of crops) without a considerable effort. Additionally, this work addresses some relevant challenges of multi-robot sensory systems, such as the mission planning and task allocation, the guidance, navigation and control of robots in greenhouses and the coordination among ground and aerial vehicles. This work has an eminently practical approach, and therefore, the system has been extensively tested both in simulations and field experiments. PMID:27376297

  5. Heterogeneous Multi-Robot System for Mapping Environmental Variables of Greenhouses.

    PubMed

    Roldán, Juan Jesús; Garcia-Aunon, Pablo; Garzón, Mario; de León, Jorge; Del Cerro, Jaime; Barrientos, Antonio

    2016-07-01

    The productivity of greenhouses highly depends on the environmental conditions of crops, such as temperature and humidity. The control and monitoring might need large sensor networks, and as a consequence, mobile sensory systems might be a more suitable solution. This paper describes the application of a heterogeneous robot team to monitor environmental variables of greenhouses. The multi-robot system includes both ground and aerial vehicles, looking to provide flexibility and improve performance. The multi-robot sensory system measures the temperature, humidity, luminosity and carbon dioxide concentration in the ground and at different heights. Nevertheless, these measurements can be complemented with other ones (e.g., the concentration of various gases or images of crops) without a considerable effort. Additionally, this work addresses some relevant challenges of multi-robot sensory systems, such as the mission planning and task allocation, the guidance, navigation and control of robots in greenhouses and the coordination among ground and aerial vehicles. This work has an eminently practical approach, and therefore, the system has been extensively tested both in simulations and field experiments.

  6. Descriptions of anisotropy and heterogeneity and their effect on ground-water flow and areas of contribution to public supply wells in a karst carbonate aquifer system

    USGS Publications Warehouse

    Knochenmus, Lari A.; Robinson, James L.

    1996-01-01

    MODFLOW and MODPATH numerical models were used to generate areas of contribution to public supply wells for simulated hypothetical anisotropy and heterogeneous carbonate aquifer systems. The simulations incorporated, to varying degrees, the anisotropy and heterogeneity observed in a karst carbonate aquifer system. These include: isotropic and homogeneous single-layer system, doubly-porous single-layer system, and interconnected vertically and horizontally heterogeneous system. The study indicated that the distribution and nature of aquifer anisotropy and heterogeneity will affect the simulated size, shape, and orientation of areas of contribution in karst carbonate aquifer systems.

  7. Spindle-shaped nanoscale yolk/shell magnetic stirring bars for heterogeneous catalysis in macro- and microscopic systems.

    PubMed

    Yang, Shuliang; Cao, Changyan; Peng, Li; Huang, Peipei; Sun, Yongbin; Wei, Fang; Song, Weiguo

    2016-01-28

    A new type of spindle-shaped nanoscale yolk/shell magnetic stirring bar containing noble metal nanoparticles was prepared. The as-synthesized Pd-Fe@meso-SiO2 not only showed impressive activity and stability as a heterogeneous catalyst in a macroscopic flask system, but also acted as an efficient nanoscale magnetic stir bar in a microscopic droplet system.

  8. M{sub 1-x}[W{sub 2}O{sub 2}X{sub 6}] with M=K{sup +}, Tl{sup +}, Ag{sup +}, Hg{sup 2+}, Pb{sup 2+}; X=Cl, Br-A class of mixed valence tungsten (IV,V) compounds with layered structures, W-W bonds and high conductivity

    SciTech Connect

    Beck, Johannes . E-mail: j.beck@uni-bonn.de; Kusterer, Christian; Hoffmann, Rolf-Dieter; Poettgen, Rainer

    2006-08-15

    The crystal structure of WOCl{sub 3}, determined on the basis of powder diffraction data (tetragonal, P4{sub 2}/mnm, a=10.6856(6), c=3.8537(2)), is isotypic to WOI{sub 3} and contains one-dimensional strands of edge-sharing double-octahedral W{sub 2}O{sub 4/2}Cl{sub 6} groups connected via common corners in trans position. A W-W bond of 2.99A is present within the planar W{sub 2}Cl{sub 6} groups. A series of non-stochiometric, mixed valence W(IV,V) compounds M{sub 1-x}[W{sub 2}O{sub 2}Cl{sub 6}] can be obtained from WOCl{sub 3} by reaction with metal halides (TlCl, KCl, PbCl{sub 2}) or by reaction of elemental Hg with WOCl{sub 4}. All were characterized by single crystal structure determinations and EDX measurements (Tl{sub 0.981(2)}[W{sub 2}O{sub 2}Cl{sub 6}]: monoclinic, C2/m, a=12.7050(4), b=3.7797(1), c=10.5651(3)A, {beta}=107.656(1){sup o}; K{sub 0.84(2)}[W{sub 2}O{sub 2}Cl{sub 6}]: monoclinic, C2/m, a=12.812(3), b=3.7779(6), c=10.196(3)A, {beta}=107.422(8){sup o}; Pb{sub 0.549(3)}[W{sub 2}O{sub 2}Cl{sub 6}]: orthorhombic, Immm,a=3.7659(1), b=9.8975(4), c=12.1332(6)A; Hg{sub 0.554(6)}[W{sub 2}O{sub 2}Cl{sub 6}]: monoclinic, C2/m, a=12.8361(8), b=3.7622(3), c=10.2581(9)A, {beta}=113.645(3){sup o}). Two representatives of this family of compounds have already been reported: Na[W{sub 2}O{sub 2}Br{sub 6}] [Y.-Q. Zhang, K. Peters, H.G. von Schnering, Z. Anorg. Allg. Chem. 624 (1998) 1415-1418] and Ag{sub 0.74}[W{sub 2}O{sub 2}Br{sub 6}] [S. Imhaine, C. Perrin, M. Sergent, Mat. Res. Bull. 33 (1998) 927-933]. The Ag containing compound can be obtained from elemental Ag and WOBr{sub 3}. The crystal structure, originally reported in the triclinic system, was redetermined and shown to be monoclinic with space group C2/m (a=13.7338(10), b=3.7769(3), c=10.7954(9)A, {beta}=112.401(3){sup o}). The crystal structures of these compounds are in close relationship to the structure of WOCl{sub 3} and all contain W{sub 2}O{sub 4/2}X{sub 6} (X=Cl, Br) double strands with the mono

  9. Automated collection of medical images for research from heterogeneous systems: trials and tribulations

    NASA Astrophysics Data System (ADS)

    Patel, M. N.; Looney, P.; Young, K.; Halling-Brown, M. D.

    2014-03-01

    Radiological imaging is fundamental within the healthcare industry and has become routinely adopted for diagnosis, disease monitoring and treatment planning. Over the past two decades both diagnostic and therapeutic imaging have undergone a rapid growth, the ability to be able to harness this large influx of medical images can provide an essential resource for research and training. Traditionally, the systematic collection of medical images for research from heterogeneous sites has not been commonplace within the NHS and is fraught with challenges including; data acquisition, storage, secure transfer and correct anonymisation. Here, we describe a semi-automated system, which comprehensively oversees the collection of both unprocessed and processed medical images from acquisition to a centralised database. The provision of unprocessed images within our repository enables a multitude of potential research possibilities that utilise the images. Furthermore, we have developed systems and software to integrate these data with their associated clinical data and annotations providing a centralised dataset for research. Currently we regularly collect digital mammography images from two sites and partially collect from a further three, with efforts to expand into other modalities and sites currently ongoing. At present we have collected 34,014 2D images from 2623 individuals. In this paper we describe our medical image collection system for research and discuss the wide spectrum of challenges faced during the design and implementation of such systems.

  10. A Modular Building Controls Virtual Test Bed for the Integrations of Heterogeneous Systems

    SciTech Connect

    Wetter, Michael; Wetter, Michael; Haves, Philip

    2008-06-30

    This paper describes the Building Controls Virtual Test Bed (BCVTB) that is currently under development at Lawrence Berkeley National Laboratory. An earlier prototype linked EnergyPlus with controls hardware through embedded SPARK models and demonstrated its value in more cost-effective envelope design and improved controls sequences for the San Francisco Federal Building. The BCVTB presented here is a more modular design based on a middleware that we built using Ptolemy II, a modular software environment for design and analysis of heterogeneous systems. Ptolemy II provides a graphical model building environment, synchronizes the exchanged data and visualizes the system evolution during run-time. Our additions to Ptolemy II allow users to couple to Ptolemy II a prototype version of EnergyPlus,MATLAB/Simulink or other simulation programs for data exchange during run-time. In future work we will also implement a BACnet interface that allows coupling BACnet compliant building automation systems to Ptolemy II. We will present the architecture of the BCVTB and explain how users can add their own simulation programs to the BCVTB. We will then present an example application in which the building envelope and the HVAC system was simulated in EnergyPlus, the supervisory control logic was simulated in MATLAB/Simulink and Ptolemy II was used to exchange data during run-time and to provide realtime visualization as the simulation progresses.

  11. Fuzziness and Heterogeneity of Benthic Metacommunities in a Complex Transitional System

    PubMed Central

    Curiel, Daniele; Cossarini, Gianpiero; Melaku Canu, Donata; Rismondo, Andrea

    2012-01-01

    communities much better than any single property can. Our results also emphasize the importance of considering heterogeneity and fuzziness when working in natural systems. PMID:23285023

  12. Heterogeneity and scaling land-atmospheric water and energy fluxes in climate systems

    NASA Technical Reports Server (NTRS)

    Wood, Eric F.

    1993-01-01

    The effects of small-scale heterogeneity in land surface characteristics on the large-scale fluxes of water and energy in land-atmosphere system has become a central focus of many of the climatology research experiments. The acquisition of high resolution land surface data through remote sensing and intensive land-climatology field experiments (like HAPEX and FIFE) has provided data to investigate the interactions between microscale land-atmosphere interactions and macroscale models. One essential research question is how to account for the small scale heterogeneities and whether 'effective' parameters can be used in the macroscale models. To address this question of scaling, three modeling experiments were performed and are reviewed in the paper. The first is concerned with the aggregation of parameters and inputs for a terrestrial water and energy balance model. The second experiment analyzed the scaling behavior of hydrologic responses during rain events and between rain events. The third experiment compared the hydrologic responses from distributed models with a lumped model that uses spatially constant inputs and parameters. The results show that the patterns of small scale variations can be represented statistically if the scale is larger than a representative elementary area scale, which appears to be about 2 - 3 times the correlation length of the process. For natural catchments this appears to be about 1 - 2 sq km. The results concerning distributed versus lumped representations are more complicated. For conditions when the processes are nonlinear, then lumping results in biases; otherwise a one-dimensional model based on 'equivalent' parameters provides quite good results. Further research is needed to fully understand these conditions.

  13. SU-E-J-60: Efficient Monte Carlo Dose Calculation On CPU-GPU Heterogeneous Systems

    SciTech Connect

    Xiao, K; Chen, D. Z; Hu, X. S; Zhou, B

    2014-06-01

    Purpose: It is well-known that the performance of GPU-based Monte Carlo dose calculation implementations is bounded by memory bandwidth. One major cause of this bottleneck is the random memory writing patterns in dose deposition, which leads to several memory efficiency issues on GPU such as un-coalesced writing and atomic operations. We propose a new method to alleviate such issues on CPU-GPU heterogeneous systems, which achieves overall performance improvement for Monte Carlo dose calculation. Methods: Dose deposition is to accumulate dose into the voxels of a dose volume along the trajectories of radiation rays. Our idea is to partition this procedure into the following three steps, which are fine-tuned for CPU or GPU: (1) each GPU thread writes dose results with location information to a buffer on GPU memory, which achieves fully-coalesced and atomic-free memory transactions; (2) the dose results in the buffer are transferred to CPU memory; (3) the dose volume is constructed from the dose buffer on CPU. We organize the processing of all radiation rays into streams. Since the steps within a stream use different hardware resources (i.e., GPU, DMA, CPU), we can overlap the execution of these steps for different streams by pipelining. Results: We evaluated our method using a Monte Carlo Convolution Superposition (MCCS) program and tested our implementation for various clinical cases on a heterogeneous system containing an Intel i7 quad-core CPU and an NVIDIA TITAN GPU. Comparing with a straightforward MCCS implementation on the same system (using both CPU and GPU for radiation ray tracing), our method gained 2-5X speedup without losing dose calculation accuracy. Conclusion: The results show that our new method improves the effective memory bandwidth and overall performance for MCCS on the CPU-GPU systems. Our proposed method can also be applied to accelerate other Monte Carlo dose calculation approaches. This research was supported in part by NSF under Grants CCF

  14. Cross-correlation spin noise spectroscopy of heterogeneous interacting spin systems

    SciTech Connect

    Roy, Dibyendu; Yang, Luyi; Crooker, Scott A.; Sinitsyn, Nikolai A.

    2015-04-30

    Interacting multi-component spin systems are ubiquitous in nature and in the laboratory. As such, investigations of inter-species spin interactions are of vital importance. Traditionally, they are studied by experimental methods that are necessarily perturbative: e.g., by intentionally polarizing or depolarizing one spin species while detecting the response of the other(s). Here, we describe and demonstrate an alternative approach based on multi-probe spin noise spectroscopy, which can reveal inter-species spin interactions - under conditions of strict thermal equilibrium - by detecting and cross-correlating the stochastic fluctuation signals exhibited by each of the constituent spin species. Specifically, we consider a two-component spin ensemble that interacts via exchange coupling, and we determine cross-correlations between their intrinsic spin fluctuations. The model is experimentally confirmed using “two-color” optical spin noise spectroscopy on a mixture of interacting Rb and Cs vapors. Noise correlations directly reveal the presence of inter-species spin exchange, without ever perturbing the system away from thermal equilibrium. These non-invasive and noise-based techniques should be generally applicable to any heterogeneous spin system in which the fluctuations of the constituent components are detectable.

  15. Cross-correlation spin noise spectroscopy of heterogeneous interacting spin systems

    DOE PAGES

    Roy, Dibyendu; Yang, Luyi; Crooker, Scott A.; Sinitsyn, Nikolai A.

    2015-04-30

    Interacting multi-component spin systems are ubiquitous in nature and in the laboratory. As such, investigations of inter-species spin interactions are of vital importance. Traditionally, they are studied by experimental methods that are necessarily perturbative: e.g., by intentionally polarizing or depolarizing one spin species while detecting the response of the other(s). Here, we describe and demonstrate an alternative approach based on multi-probe spin noise spectroscopy, which can reveal inter-species spin interactions - under conditions of strict thermal equilibrium - by detecting and cross-correlating the stochastic fluctuation signals exhibited by each of the constituent spin species. Specifically, we consider a two-component spinmore » ensemble that interacts via exchange coupling, and we determine cross-correlations between their intrinsic spin fluctuations. The model is experimentally confirmed using “two-color” optical spin noise spectroscopy on a mixture of interacting Rb and Cs vapors. Noise correlations directly reveal the presence of inter-species spin exchange, without ever perturbing the system away from thermal equilibrium. These non-invasive and noise-based techniques should be generally applicable to any heterogeneous spin system in which the fluctuations of the constituent components are detectable.« less

  16. IRON-60 HETEROGENEITY AND INCOMPLETE ISOTOPE MIXING IN THE EARLY SOLAR SYSTEM

    SciTech Connect

    Quitte, Ghylaine; Markowski, Agnes; Latkoczy, Christopher; Gabriel, Aron; Pack, Andreas

    2010-09-10

    Short-lived radionuclides (e.g., {sup 26}Al, {sup 53}Mn, {sup 60}Fe, {sup 182}Hf) are widely used to refine the chronology of the early solar system. They provide chronological information, however, only if they were homogeneously distributed in the source region of the objects under scrutiny at the time of their formation. With the high level of precision now achieved on isotopic measurements, very short time intervals can in principle be resolved and a precise evaluation of the initial homogeneity degree becomes increasingly crucial. High-precision nickel isotope data for differentiated meteorites (angrites, ureilites) and chondritic (CB) components allow us to test the initial distribution of radioactive {sup 60}Fe and stable Ni isotopes. Although these meteorites appear to have formed nearly contemporaneously, they yield variable initial {sup 60}Fe/{sup 56}Fe ratios. Besides, the CB metal nodules and ureilite silicates show nucleosynthetic anomalies. The new data presented here do not confirm the recently inferred late injection of {sup 60}Fe into the protoplanetary disk. Instead, live {sup 60}Fe was present, but heterogeneously distributed, from the start of the solar system, revealing an incomplete mixing of material from various nucleosynthetic sources and restricting the use of the {sup 60}Fe-{sup 60}Ni system as a chronometer.

  17. A dimensionally-heterogeneous closed-loop model for the cardiovascular system and its applications.

    PubMed

    Blanco, P J; Feijóo, R A

    2013-05-01

    In the present work a computational model of the entire cardiovascular system is developed using heterogeneous mathematical representations. This model integrates different levels of detail for the blood circulation. The arterial tree is described by a one dimensional model in order to simulate the wave propagation phenomena that take place at the larger arterial vessels. The inflow and outflow locations of this 1D model are coupled with lumped parameter descriptions of the remainder part of the circulatory system, closing the loop. The four cardiac valves are considered using a valve model which allows for stenoses and regurgitation phenomena. In addition, full 3D geometrical models of arterial districts are embedded in this closed-loop circuit to model the local blood flow in specific vessels. This kind of detailed closed-loop network for the cardiovascular system allows hemodynamics analyses of patient-specific arterial district, delivering naturally the appropriate boundary conditions for different cardiovascular scenarios. An example of application involving the effect of aortic insufficiency on the local hemodynamics of a cerebral aneurism is provided as a motivation to reproduce, through numerical simulation, the hemodynamic environment in patients suffering from infective endocarditis and mycotic aneurisms. The need for incorporating homeostatic control mechanisms is also discussed in view of the large sensitivity observed in the results, noting that this kind of integrative modeling allows such incorporation.

  18. Universality and nonuniversality of mobility in heterogeneous single-file systems and Rouse chains

    NASA Astrophysics Data System (ADS)

    Lomholt, Michael A.; Ambjörnsson, Tobias

    2014-03-01

    We study analytically the tracer particle mobility in single-file systems with distributed friction constants. Our system serves as a prototype for nonequilibrium, heterogeneous, strongly interacting Brownian systems. The long time dynamics for such a single-file setup belongs to the same universality class as the Rouse model with dissimilar beads. The friction constants are drawn from a density ϱ (ξ), and we derive an asymptotically exact solution for the mobility distribution P [μ0(s)], where μ0(s) is the Laplace-space mobility. If ϱ is light tailed (first moment exists), we find a self-averaging behavior: P[μ0(s )]=δ[μ0(s)-μ(s)], with μ(s )∝s1/2. When ϱ(ξ) is heavy tailed, ϱ(ξ )≃ξ-1-α(0<α<1) for large ξ, we obtain moments <[μs(0)]n>∝sβn, where β =1/(1+α) and there is no self-averaging. The results are corroborated by simulations.

  19. Universality and nonuniversality of mobility in heterogeneous single-file systems and Rouse chains.

    PubMed

    Lomholt, Michael A; Ambjörnsson, Tobias

    2014-03-01

    We study analytically the tracer particle mobility in single-file systems with distributed friction constants. Our system serves as a prototype for nonequilibrium, heterogeneous, strongly interacting Brownian systems. The long time dynamics for such a single-file setup belongs to the same universality class as the Rouse model with dissimilar beads. The friction constants are drawn from a density ϱ(ξ), and we derive an asymptotically exact solution for the mobility distribution P[μ0(s)], where μ0(s) is the Laplace-space mobility. If ϱ is light tailed (first moment exists), we find a self-averaging behavior: P[μ0(s)]=δ[μ0(s)-μ(s)], with μ(s)∝s1/2. When ϱ(ξ) is heavy tailed, ϱ(ξ)≃ξ-1-α(0<α<1) for large ξ, we obtain moments 〈[μs(0)]n〉∝sβn, where β=1/(1+α) and there is no self-averaging. The results are corroborated by simulations.

  20. Incorporating MRI structural information into bioluminescence tomography: system, heterogeneous reconstruction and in vivo quantification

    PubMed Central

    Zhang, Jun; Chen, Duofang; Liang, Jimin; Xue, Huadan; Lei, Jing; Wang, Qin; Chen, Dongmei; Meng, Ming; Jin, Zhengyu; Tian, Jie

    2014-01-01

    Combining two or more imaging modalities to provide complementary information has become commonplace in clinical practice and in preclinical and basic biomedical research. By incorporating the structural information provided by computed tomography (CT) or magnetic resonance imaging (MRI), the ill poseness nature of bioluminescence tomography (BLT) can be reduced significantly, thus improve the accuracies of reconstruction and in vivo quantification. In this paper, we present a small animal imaging system combining multi-view and multi-spectral BLT with MRI. The independent MRI-compatible optical device is placed at the end of the clinical MRI scanner. The small animal is transferred between the light tight chamber of the optical device and the animal coil of MRI via a guide rail during the experiment. After the optical imaging and MRI scanning procedures are finished, the optical images are mapped onto the MRI surface by interactive registration between boundary of optical images and silhouette of MRI. Then, incorporating the MRI structural information, a heterogeneous reconstruction algorithm based on finite element method (FEM) with L 1 normalization is used to reconstruct the position, power and region of the light source. In order to validate the feasibility of the system, we conducted experiments of nude mice model implanted with artificial light source and quantitative analysis of tumor inoculation model with MDA-231-GFP-luc. Preliminary results suggest the feasibility and effectiveness of the prototype system. PMID:24940545

  1. Computer-aided modeling of heterogeneous, two-dimensional, groundwater system

    NASA Astrophysics Data System (ADS)

    Rashid, A.; Aziz, A.; Wong, Kau-Fui V.

    1992-10-01

    An interactive groundwater modeling (IGWM) package has been developed on a dedicated artificial-intelligence computer. The package consists of a graphic interface and groundwater models. The purpose of the graphic interface is to facilitate modeling tasks such as defining the groundwater system and the input stresses, managing the numerical solution, and updating the hydraulic parameters. The package is developed in Symbolics Common LISP language and uses numerical models written in LISP. During the modeling, the numerical grid is projected on the graphic screen to serve as an interface to the two-dimensional (2-D) arrays where the magnitude of the hydraulic parameters are stored. The user of the package recreates the scenario that simulates a natural groundwater system by symbolically manipulating the nodes of the numerical grid, assigning patterns to the nodes, and setting the contents of the 2-D arrays. These steps are accomplished through execution of commands available from the command menu. Layers of patterns containing the information regarding the hydraulic parameters are stored in the computer memory and are redisplayed at the appropriate update sequence by the package automatically. The modeling process is continued until a satisfactory match is obtained between the computed piezometric head and the field-observed piezometric head. The use of the package in modeling heterogeneous groundwater systems is demonstrated by a field application. The numerical solutions obtained using the package were compared with other published results.

  2. Computer-aided multiple-head 3D printing system for printing of heterogeneous organ/tissue constructs

    NASA Astrophysics Data System (ADS)

    Jung, Jin Woo; Lee, Jung-Seob; Cho, Dong-Woo

    2016-02-01

    Recently, much attention has focused on replacement or/and enhancement of biological tissues via the use of cell-laden hydrogel scaffolds with an architecture that mimics the tissue matrix, and with the desired three-dimensional (3D) external geometry. However, mimicking the heterogeneous tissues that most organs and tissues are formed of is challenging. Although multiple-head 3D printing systems have been proposed for fabricating heterogeneous cell-laden hydrogel scaffolds, to date only the simple exterior form has been realized. Here we describe a computer-aided design and manufacturing (CAD/CAM) system for this application. We aim to develop an algorithm to enable easy, intuitive design and fabrication of a heterogeneous cell-laden hydrogel scaffolds with a free-form 3D geometry. The printing paths of the scaffold are automatically generated from the 3D CAD model, and the scaffold is then printed by dispensing four materials; i.e., a frame, two kinds of cell-laden hydrogel and a support. We demonstrated printing of heterogeneous tissue models formed of hydrogel scaffolds using this approach, including the outer ear, kidney and tooth tissue. These results indicate that this approach is particularly promising for tissue engineering and 3D printing applications to regenerate heterogeneous organs and tissues with tailored geometries to treat specific defects or injuries.

  3. Computer-aided multiple-head 3D printing system for printing of heterogeneous organ/tissue constructs.

    PubMed

    Jung, Jin Woo; Lee, Jung-Seob; Cho, Dong-Woo

    2016-01-01

    Recently, much attention has focused on replacement or/and enhancement of biological tissues via the use of cell-laden hydrogel scaffolds with an architecture that mimics the tissue matrix, and with the desired three-dimensional (3D) external geometry. However, mimicking the heterogeneous tissues that most organs and tissues are formed of is challenging. Although multiple-head 3D printing systems have been proposed for fabricating heterogeneous cell-laden hydrogel scaffolds, to date only the simple exterior form has been realized. Here we describe a computer-aided design and manufacturing (CAD/CAM) system for this application. We aim to develop an algorithm to enable easy, intuitive design and fabrication of a heterogeneous cell-laden hydrogel scaffolds with a free-form 3D geometry. The printing paths of the scaffold are automatically generated from the 3D CAD model, and the scaffold is then printed by dispensing four materials; i.e., a frame, two kinds of cell-laden hydrogel and a support. We demonstrated printing of heterogeneous tissue models formed of hydrogel scaffolds using this approach, including the outer ear, kidney and tooth tissue. These results indicate that this approach is particularly promising for tissue engineering and 3D printing applications to regenerate heterogeneous organs and tissues with tailored geometries to treat specific defects or injuries. PMID:26899876

  4. Computer-aided multiple-head 3D printing system for printing of heterogeneous organ/tissue constructs

    PubMed Central

    Jung, Jin Woo; Lee, Jung-Seob; Cho, Dong-Woo

    2016-01-01

    Recently, much attention has focused on replacement or/and enhancement of biological tissues via the use of cell-laden hydrogel scaffolds with an architecture that mimics the tissue matrix, and with the desired three-dimensional (3D) external geometry. However, mimicking the heterogeneous tissues that most organs and tissues are formed of is challenging. Although multiple-head 3D printing systems have been proposed for fabricating heterogeneous cell-laden hydrogel scaffolds, to date only the simple exterior form has been realized. Here we describe a computer-aided design and manufacturing (CAD/CAM) system for this application. We aim to develop an algorithm to enable easy, intuitive design and fabrication of a heterogeneous cell-laden hydrogel scaffolds with a free-form 3D geometry. The printing paths of the scaffold are automatically generated from the 3D CAD model, and the scaffold is then printed by dispensing four materials; i.e., a frame, two kinds of cell-laden hydrogel and a support. We demonstrated printing of heterogeneous tissue models formed of hydrogel scaffolds using this approach, including the outer ear, kidney and tooth tissue. These results indicate that this approach is particularly promising for tissue engineering and 3D printing applications to regenerate heterogeneous organs and tissues with tailored geometries to treat specific defects or injuries. PMID:26899876

  5. Computer-aided multiple-head 3D printing system for printing of heterogeneous organ/tissue constructs.

    PubMed

    Jung, Jin Woo; Lee, Jung-Seob; Cho, Dong-Woo

    2016-02-22

    Recently, much attention has focused on replacement or/and enhancement of biological tissues via the use of cell-laden hydrogel scaffolds with an architecture that mimics the tissue matrix, and with the desired three-dimensional (3D) external geometry. However, mimicking the heterogeneous tissues that most organs and tissues are formed of is challenging. Although multiple-head 3D printing systems have been proposed for fabricating heterogeneous cell-laden hydrogel scaffolds, to date only the simple exterior form has been realized. Here we describe a computer-aided design and manufacturing (CAD/CAM) system for this application. We aim to develop an algorithm to enable easy, intuitive design and fabrication of a heterogeneous cell-laden hydrogel scaffolds with a free-form 3D geometry. The printing paths of the scaffold are automatically generated from the 3D CAD model, and the scaffold is then printed by dispensing four materials; i.e., a frame, two kinds of cell-laden hydrogel and a support. We demonstrated printing of heterogeneous tissue models formed of hydrogel scaffolds using this approach, including the outer ear, kidney and tooth tissue. These results indicate that this approach is particularly promising for tissue engineering and 3D printing applications to regenerate heterogeneous organs and tissues with tailored geometries to treat specific defects or injuries.

  6. Synthesis, crystal structure and magnetic studies of tetranuclear hydroxo and ligand bridged [Co4(μ3-OH)2(μ2-dea)2(L-L)4]4Cl·8H2O [L-L = 2,2'-bipyridine or 1,10-phenanthroline] complexes with mixed valence defect dicubane core.

    PubMed

    Siddiqi, Zafar A; Siddique, Armeen; Shahid, M; Khalid, Mohd; Sharma, Prashant K; Anjuli; Ahmad, Musheer; Kumar, Sarvendra; Lan, Yanhua; Powell, Annie K

    2013-07-14

    X-ray crystallography of the title complexes indicates a discrete mixed valence (Co2(II)-Co2(III)) defect dicubane molecular unit where each cobalt nucleus attains a distorted octahedral geometry. The α-diimine (L-L) chelator coordinated to each cobalt ion stops further polymerization or nuclearization. The water molecules in the lattice play a crucial role in the formation of the supramolecular architectures. Magnetic data were analyzed using the effective spin-1/2 Hamiltonian approach and the parameters are, J = 115(6) K, ΔJ = -57.0(1.2) K, g(xy) = 3.001(25), and g(z) = 7.214(7) for 1 and J = 115(12) K, ΔJ = -58.5(2.5) K, g(xy) = 3.34(5), and g(z) = 6.599(12) for 2 suggesting that only the g matrices are prone to the change of α-diimine chelator.

  7. Next Generation Workload Management System For Big Data on Heterogeneous Distributed Computing

    SciTech Connect

    Klimentov, A.; Buncic, P.; De, K.; Jha, S.; Maeno, T.; Mount, R.; Nilsson, P.; Oleynik, D.; Panitkin, S.; Petrosyan, A.; Porter, R. J.; Read, K. F.; Vaniachine, A.; Wells, J. C.; Wenaus, T.

    2015-05-22

    The Large Hadron Collider (LHC), operating at the international CERN Laboratory in Geneva, Switzerland, is leading Big Data driven scientific explorations. Experiments at the LHC explore the fundamental nature of matter and the basic forces that shape our universe, and were recently credited for the discovery of a Higgs boson. ATLAS and ALICE are the largest collaborations ever assembled in the sciences and are at the forefront of research at the LHC. To address an unprecedented multi-petabyte data processing challenge, both experiments rely on a heterogeneous distributed computational infrastructure. The ATLAS experiment uses PanDA (Production and Data Analysis) Workload Management System (WMS) for managing the workflow for all data processing on hundreds of data centers. Through PanDA, ATLAS physicists see a single computing facility that enables rapid scientific breakthroughs for the experiment, even though the data centers are physically scattered all over the world. The scale is demonstrated by the following numbers: PanDA manages O(102) sites, O(105) cores, O(108) jobs per year, O(103) users, and ATLAS data volume is O(1017) bytes. In 2013 we started an ambitious program to expand PanDA to all available computing resources, including opportunistic use of commercial and academic clouds and Leadership Computing Facilities (LCF). The project titled 'Next Generation Workload Management and Analysis System for Big Data' (BigPanDA) is funded by DOE ASCR and HEP. Extending PanDA to clouds and LCF presents new challenges in managing heterogeneity and supporting workflow. The BigPanDA project is underway to setup and tailor PanDA at the Oak Ridge Leadership Computing Facility (OLCF) and at the National Research Center "Kurchatov Institute" together with ALICE distributed computing and ORNL computing professionals. Our approach to integration of HPC platforms at the OLCF and elsewhere is to reuse, as much as

  8. Next Generation Workload Management System For Big Data on Heterogeneous Distributed Computing

    DOE PAGES

    Klimentov, A.; Buncic, P.; De, K.; Jha, S.; Maeno, T.; Mount, R.; Nilsson, P.; Oleynik, D.; Panitkin, S.; Petrosyan, A.; et al

    2015-05-22

    The Large Hadron Collider (LHC), operating at the international CERN Laboratory in Geneva, Switzerland, is leading Big Data driven scientific explorations. Experiments at the LHC explore the fundamental nature of matter and the basic forces that shape our universe, and were recently credited for the discovery of a Higgs boson. ATLAS and ALICE are the largest collaborations ever assembled in the sciences and are at the forefront of research at the LHC. To address an unprecedented multi-petabyte data processing challenge, both experiments rely on a heterogeneous distributed computational infrastructure. The ATLAS experiment uses PanDA (Production and Data Analysis) Workload Managementmore » System (WMS) for managing the workflow for all data processing on hundreds of data centers. Through PanDA, ATLAS physicists see a single computing facility that enables rapid scientific breakthroughs for the experiment, even though the data centers are physically scattered all over the world. The scale is demonstrated by the following numbers: PanDA manages O(102) sites, O(105) cores, O(108) jobs per year, O(103) users, and ATLAS data volume is O(1017) bytes. In 2013 we started an ambitious program to expand PanDA to all available computing resources, including opportunistic use of commercial and academic clouds and Leadership Computing Facilities (LCF). The project titled 'Next Generation Workload Management and Analysis System for Big Data' (BigPanDA) is funded by DOE ASCR and HEP. Extending PanDA to clouds and LCF presents new challenges in managing heterogeneity and supporting workflow. The BigPanDA project is underway to setup and tailor PanDA at the Oak Ridge Leadership Computing Facility (OLCF) and at the National Research Center "Kurchatov Institute" together with ALICE distributed computing and ORNL computing professionals. Our approach to integration of HPC platforms at the OLCF and elsewhere is to reuse, as much as possible, existing components of the PanDA system

  9. Next Generation Workload Management System For Big Data on Heterogeneous Distributed Computing

    NASA Astrophysics Data System (ADS)

    Klimentov, A.; Buncic, P.; De, K.; Jha, S.; Maeno, T.; Mount, R.; Nilsson, P.; Oleynik, D.; Panitkin, S.; Petrosyan, A.; Porter, R. J.; Read, K. F.; Vaniachine, A.; Wells, J. C.; Wenaus, T.

    2015-05-01

    The Large Hadron Collider (LHC), operating at the international CERN Laboratory in Geneva, Switzerland, is leading Big Data driven scientific explorations. Experiments at the LHC explore the fundamental nature of matter and the basic forces that shape our universe, and were recently credited for the discovery of a Higgs boson. ATLAS and ALICE are the largest collaborations ever assembled in the sciences and are at the forefront of research at the LHC. To address an unprecedented multi-petabyte data processing challenge, both experiments rely on a heterogeneous distributed computational infrastructure. The ATLAS experiment uses PanDA (Production and Data Analysis) Workload Management System (WMS) for managing the workflow for all data processing on hundreds of data centers. Through PanDA, ATLAS physicists see a single computing facility that enables rapid scientific breakthroughs for the experiment, even though the data centers are physically scattered all over the world. The scale is demonstrated by the following numbers: PanDA manages O(102) sites, O(105) cores, O(108) jobs per year, O(103) users, and ATLAS data volume is O(1017) bytes. In 2013 we started an ambitious program to expand PanDA to all available computing resources, including opportunistic use of commercial and academic clouds and Leadership Computing Facilities (LCF). The project titled ‘Next Generation Workload Management and Analysis System for Big Data’ (BigPanDA) is funded by DOE ASCR and HEP. Extending PanDA to clouds and LCF presents new challenges in managing heterogeneity and supporting workflow. The BigPanDA project is underway to setup and tailor PanDA at the Oak Ridge Leadership Computing Facility (OLCF) and at the National Research Center "Kurchatov Institute" together with ALICE distributed computing and ORNL computing professionals. Our approach to integration of HPC platforms at the OLCF and elsewhere is to reuse, as much as possible, existing components of the PanDA system. We

  10. 3D heterogeneous sensor system on a chip for defense and security applications

    NASA Astrophysics Data System (ADS)

    Bhansali, Shekhar; Chapman, Glenn H.; Friedman, Eby G.; Ismail, Yehea; Mukund, P. R.; Tebbe, Dennis; Jain, Vijay K.

    2004-09-01

    This paper describes a new concept for ultra-small, ultra-compact, unattended multi-phenomenological sensor systems for rapid deployment, with integrated classification-and-decision-information extraction capability from a sensed environment. We discuss a unique approach, namely a 3-D Heterogeneous System on a Chip (HSoC) in order to achieve a minimum 10X reduction in weight, volume, and power and a 10X or greater increase in capability and reliability -- over the alternative planar approaches. These gains will accrue from (a) the avoidance of long on-chip interconnects and chip-to-chip bonding wires, and (b) the cohabitation of sensors, preprocessing analog circuitry, digital logic and signal processing, and RF devices in the same compact volume. A specific scenario is discussed in detail wherein a set of four types of sensors, namely an array of acoustic and seismic sensors, an active pixel sensor array, and an uncooled IR imaging array are placed on a common sensor plane. The other planes include an analog plane consisting of transductors and A/D converters. The digital processing planes provide the necessary processing and intelligence capability. The remaining planes provide for wireless communications/networking capability. When appropriate, this processing and decision-making will be accomplished on a collaborative basis among the distributed sensor nodes through a wireless network.

  11. Heterogeneity and scaling in soil-vegetation atmosphere systems: implications for pattern analysis (Invited)

    NASA Astrophysics Data System (ADS)

    Pachepsky, Y. A.

    2009-12-01

    Advances in sensor physics and technology create opportunities for explicit consideration of patterns in soil-vegetation-atmosphere systems (SVAS). The purpose of this talk is to provoke discussion on the current status of pattern analysis and interpretation in SVAS. The explicit consideration of patterns requires observations and analysis at scales that are both coarser and finer than the scale of interest. Within-scale scaling relationships are often observed in SVAS components. However, direct scaling relationships have not been discovered between scales, possibly because the different scales provide different types of information about the SVAS, use different variables to characterize SVAS, and exhibit different variability of the system. To transcend the scales, models are needed that explicitly treat the fine-scale heterogeneity and rare occurrences that control processes at the coarser scale. As patterns are generated from simulations and or/or observations, methods are needed for pattern characterization and comparison. One promising direction here is the symbolic representation of patterns which leads to the exploitation of methods developed in the bioinformatics community. Examples drawn from soil hydrology and micrometeorology will be used in illustrations to make the argument that observation and analysis of patterns is the important part of understanding and quantifying relationships between structure, functioning and self-organization in SVAS and their components.

  12. Effect of geometry on concentration polarization in realistic heterogeneous permselective systems

    NASA Astrophysics Data System (ADS)

    Green, Yoav; Shloush, Shahar; Yossifon, Gilad

    2014-04-01

    This study extends previous analytical solutions of concentration polarization occurring solely in the depleted region, to the more realistic geometry consisting of a three-dimensional (3D) heterogeneous ion-permselective medium connecting two opposite microchambers (i.e., a three-layer system). Under the local electroneutrality approximation, the separation of variable methods is used to derive an analytical solution of the electrodiffusive problem for the two opposing asymmetric microchambers. The assumption of an ideal permselective medium allows for the analytic calculation of the 3D concentration and electric potential distributions as well as a current-voltage relation. It is shown that any asymmetry in the microchamber geometries will result in current rectification. Moreover, it is demonstrated that for non-negligible microchamber resistances, the conductance does not exhibit the expected saturation at low concentrations but instead shows a continuous decrease. The results are intended to facilitate a more direct comparison between theory and experiments, as now the voltage drop is across a realistic 3D and three-layer system.

  13. A DAG Scheduling Scheme on Heterogeneous Computing Systems Using Tuple-Based Chemical Reaction Optimization

    PubMed Central

    Jiang, Yuyi; Shao, Zhiqing; Guo, Yi

    2014-01-01

    A complex computing problem can be solved efficiently on a system with multiple computing nodes by dividing its implementation code into several parallel processing modules or tasks that can be formulated as directed acyclic graph (DAG) problems. The DAG jobs may be mapped to and scheduled on the computing nodes to minimize the total execution time. Searching an optimal DAG scheduling solution is considered to be NP-complete. This paper proposed a tuple molecular structure-based chemical reaction optimization (TMSCRO) method for DAG scheduling on heterogeneous computing systems, based on a very recently proposed metaheuristic method, chemical reaction optimization (CRO). Comparing with other CRO-based algorithms for DAG scheduling, the design of tuple reaction molecular structure and four elementary reaction operators of TMSCRO is more reasonable. TMSCRO also applies the concept of constrained critical paths (CCPs), constrained-critical-path directed acyclic graph (CCPDAG) and super molecule for accelerating convergence. In this paper, we have also conducted simulation experiments to verify the effectiveness and efficiency of TMSCRO upon a large set of randomly generated graphs and the graphs for real world problems. PMID:25143977

  14. A DAG scheduling scheme on heterogeneous computing systems using tuple-based chemical reaction optimization.

    PubMed

    Jiang, Yuyi; Shao, Zhiqing; Guo, Yi

    2014-01-01

    A complex computing problem can be solved efficiently on a system with multiple computing nodes by dividing its implementation code into several parallel processing modules or tasks that can be formulated as directed acyclic graph (DAG) problems. The DAG jobs may be mapped to and scheduled on the computing nodes to minimize the total execution time. Searching an optimal DAG scheduling solution is considered to be NP-complete. This paper proposed a tuple molecular structure-based chemical reaction optimization (TMSCRO) method for DAG scheduling on heterogeneous computing systems, based on a very recently proposed metaheuristic method, chemical reaction optimization (CRO). Comparing with other CRO-based algorithms for DAG scheduling, the design of tuple reaction molecular structure and four elementary reaction operators of TMSCRO is more reasonable. TMSCRO also applies the concept of constrained critical paths (CCPs), constrained-critical-path directed acyclic graph (CCPDAG) and super molecule for accelerating convergence. In this paper, we have also conducted simulation experiments to verify the effectiveness and efficiency of TMSCRO upon a large set of randomly generated graphs and the graphs for real world problems.

  15. System Miniaturization Via Heterogeneous Integration of Electronic Devices for Deep Space Missions

    NASA Technical Reports Server (NTRS)

    DelCastillo, L.; Schatzel, D. V.; Graber, R. W.; Mottiwala, A.

    2001-01-01

    The scientific devices designed for each of the Outer Planets Program Focuses will likely be groundbreaking not only with respect to their scientific role but also regarding the electronics required to perform such investigations. In the past, the performance of packaged electronics was limited by the components themselves, with minimal influence of the packaging technology. The rapid development of integrated circuit technology, however, has drastically increased the importance of packaging technology in the ultimate performance of devices. If not carefully considered in the overall design, the packaging may become the limiting factor in the operation of the system. Although industry is responsible for several significant accomplishments in the field of electronics packaging, deep space/outer planet missions must take into account additional requirements such as extremely low temperatures, high radiation levels, hermetic sealing, and severe size and weight limitations. Therefore, the present investigation has been designed to meet the needs of NASA's sensor intensive outer planets program by combining (using flip chip technology) an array of devices (including analog, digital, power volt-age, passives, and MEMS) into a miniaturized heterogeneous system and utilizing optical buses to enable autonomy. Additional information is contained in the original extended abstract.

  16. Photochemistry in a heterogeneous system: chlorophyll-sensitized reduction of p-dinitrobenzene by hydrazobenzene

    SciTech Connect

    Seely, G.R.; Haggy, G.A.

    1987-01-15

    The photoreduction of p-dinitrobenzene, sensitized by aqueous suspensions of chlorophyll a with other amphiphiles adsorbed onto polyethylene-tetradecane particles, differs in some respects from the photoreduction in solution. The reaction proceeds in two stages. The products of the first stage, N-(p-nitrophenyl)hydroxylamine and azobenzene, are separated into the aqueous and hydrocarbon particle phases, respectively. The nature of the second stage of reaction is uncertain, but observations are best explained by a reduction of N-(p-nitrophenyl)hydroxylamine to 4,4'-dinitrohydrazobenzene. The quantum yield of photoreduction to the hydroxylamine does not seem to correlate at all with quantum yield of fluorescence of the sensitizing particles. This and the relative magnitudes of the yields suggest that the principal photochemical reaction is reduction of dinitrobenzene not by the excited singlet state of chlorophyll or by the triplet state formed directly by intersystem crossing but by high-energy ion pair states or perhaps triplets formed from them by decay. Absorption spectrometry in the heterogeneous system is complicated by superposition of the so-called sieve effect on the path-length enhancement effect of the highly scattering system. The role of the interface between the particle and aqueous phases on the course of the reaction is discussed.

  17. Effects of dispersal on total biomass in a patchy, heterogeneous system: Analysis and experiment.

    PubMed

    Zhang, Bo; Liu, Xin; DeAngelis, D L; Ni, Wei-Ming; Wang, G Geoff

    2015-06-01

    An intriguing recent result from mathematics is that a population diffusing at an intermediate rate in an environment in which resources vary spatially will reach a higher total equilibrium biomass than the population in an environment in which the same total resources are distributed homogeneously. We extended the current mathematical theory to apply to logistic growth and also showed that the result applies to patchy systems with dispersal among patches, both for continuous and discrete time. This allowed us to make specific predictions, through simulations, concerning the biomass dynamics, which were verified by a laboratory experiment. The experiment was a study of biomass growth of duckweed (Lemna minor Linn.), where the resources (nutrients added to water) were distributed homogeneously among a discrete series of water-filled containers in one treatment, and distributed heterogeneously in another treatment. The experimental results showed that total biomass peaked at an intermediate, relatively low, diffusion rate, higher than the total carrying capacity of the system and agreeing with the simulation model. The implications of the experiment to dynamics of source, sink, and pseudo-sink dynamics are discussed. PMID:25817196

  18. Structures of heterogeneous systems determined using XFEL pulses in the face of radiation damage

    NASA Astrophysics Data System (ADS)

    Young, Linda; Ho, Phay; Knight, Chris; Bostedt, Christoph; Faigl, Gyula; Tegze, Miklos

    2016-05-01

    Intense, femtosecond x-ray free-electron laser pulses are a promising tool for studying the structure and dynamics of complex systems at atomic resolution. Our previous efforts, using an atomistic quantum/classical model to track the dynamical evolution of ions and electrons throughout a femtosecond x-ray pulse and out to picosecond timescales, focused on quantifying the effects of radiation damage on homogeneous rare gas clusters for imaging applications in an ideal situation. In these studies, the entire 3D Q-space scattering pattern was computed and available for reconstruction of the initial structure. However, a realistic representation of an experiment would feature a collection of noisy 2D scattering patterns, from which orientation would first be required to generate the 3D Q-space distribution from which solution of the phase problem and reconstruction would then proceed. We will present the first results of these efforts on heterogeneous systems. This work was supported by the U.S. Department of Energy, Office of Science, Basic Energy Sciences, Chemical Sciences, Geosciences, and Biosciences Division.

  19. Biologically-inspired approaches for self-organization, adaptation, and collaboration of heterogeneous autonomous systems

    NASA Astrophysics Data System (ADS)

    Steinberg, Marc

    2011-06-01

    This paper presents a selective survey of theoretical and experimental progress in the development of biologicallyinspired approaches for complex surveillance and reconnaissance problems with multiple, heterogeneous autonomous systems. The focus is on approaches that may address ISR problems that can quickly become mathematically intractable or otherwise impractical to implement using traditional optimization techniques as the size and complexity of the problem is increased. These problems require dealing with complex spatiotemporal objectives and constraints at a variety of levels from motion planning to task allocation. There is also a need to ensure solutions are reliable and robust to uncertainty and communications limitations. First, the paper will provide a short introduction to the current state of relevant biological research as relates to collective animal behavior. Second, the paper will describe research on largely decentralized, reactive, or swarm approaches that have been inspired by biological phenomena such as schools of fish, flocks of birds, ant colonies, and insect swarms. Next, the paper will discuss approaches towards more complex organizational and cooperative mechanisms in team and coalition behaviors in order to provide mission coverage of large, complex areas. Relevant team behavior may be derived from recent advances in understanding of the social and cooperative behaviors used for collaboration by tens of animals with higher-level cognitive abilities such as mammals and birds. Finally, the paper will briefly discuss challenges involved in user interaction with these types of systems.

  20. Effects of dispersal on total biomass in a patchy, heterogeneous system: analysis and experiment.

    USGS Publications Warehouse

    Zhang, Bo; Liu, Xin; DeAngelis, Donald L.; Ni, Wei-Ming; Wang, G Geoff

    2015-01-01

    An intriguing recent result from mathematics is that a population diffusing at an intermediate rate in an environment in which resources vary spatially will reach a higher total equilibrium biomass than the population in an environment in which the same total resources are distributed homogeneously. We extended the current mathematical theory to apply to logistic growth and also showed that the result applies to patchy systems with dispersal among patches, both for continuous and discrete time. This allowed us to make specific predictions, through simulations, concerning the biomass dynamics, which were verified by a laboratory experiment. The experiment was a study of biomass growth of duckweed (Lemna minor Linn.), where the resources (nutrients added to water) were distributed homogeneously among a discrete series of water-filled containers in one treatment, and distributed heterogeneously in another treatment. The experimental results showed that total biomass peaked at an intermediate, relatively low, diffusion rate, higher than the total carrying capacity of the system and agreeing with the simulation model. The implications of the experiment to dynamics of source, sink, and pseudo-sink dynamics are discussed.

  1. Deep graphs-A general framework to represent and analyze heterogeneous complex systems across scales.

    PubMed

    Traxl, Dominik; Boers, Niklas; Kurths, Jürgen

    2016-06-01

    Network theory has proven to be a powerful tool in describing and analyzing systems by modelling the relations between their constituent objects. Particularly in recent years, a great progress has been made by augmenting "traditional" network theory in order to account for the multiplex nature of many networks, multiple types of connections between objects, the time-evolution of networks, networks of networks and other intricacies. However, existing network representations still lack crucial features in order to serve as a general data analysis tool. These include, most importantly, an explicit association of information with possibly heterogeneous types of objects and relations, and a conclusive representation of the properties of groups of nodes as well as the interactions between such groups on different scales. In this paper, we introduce a collection of definitions resulting in a framework that, on the one hand, entails and unifies existing network representations (e.g., network of networks and multilayer networks), and on the other hand, generalizes and extends them by incorporating the above features. To implement these features, we first specify the nodes and edges of a finite graph as sets of properties (which are permitted to be arbitrary mathematical objects). Second, the mathematical concept of partition lattices is transferred to the network theory in order to demonstrate how partitioning the node and edge set of a graph into supernodes and superedges allows us to aggregate, compute, and allocate information on and between arbitrary groups of nodes. The derived partition lattice of a graph, which we denote by deep graph, constitutes a concise, yet comprehensive representation that enables the expression and analysis of heterogeneous properties, relations, and interactions on all scales of a complex system in a self-contained manner. Furthermore, to be able to utilize existing network-based methods and models, we derive different representations of

  2. Deep graphs—A general framework to represent and analyze heterogeneous complex systems across scales

    NASA Astrophysics Data System (ADS)

    Traxl, Dominik; Boers, Niklas; Kurths, Jürgen

    2016-06-01

    Network theory has proven to be a powerful tool in describing and analyzing systems by modelling the relations between their constituent objects. Particularly in recent years, a great progress has been made by augmenting "traditional" network theory in order to account for the multiplex nature of many networks, multiple types of connections between objects, the time-evolution of networks, networks of networks and other intricacies. However, existing network representations still lack crucial features in order to serve as a general data analysis tool. These include, most importantly, an explicit association of information with possibly heterogeneous types of objects and relations, and a conclusive representation of the properties of groups of nodes as well as the interactions between such groups on different scales. In this paper, we introduce a collection of definitions resulting in a framework that, on the one hand, entails and unifies existing network representations (e.g., network of networks and multilayer networks), and on the other hand, generalizes and extends them by incorporating the above features. To implement these features, we first specify the nodes and edges of a finite graph as sets of properties (which are permitted to be arbitrary mathematical objects). Second, the mathematical concept of partition lattices is transferred to the network theory in order to demonstrate how partitioning the node and edge set of a graph into supernodes and superedges allows us to aggregate, compute, and allocate information on and between arbitrary groups of nodes. The derived partition lattice of a graph, which we denote by deep graph, constitutes a concise, yet comprehensive representation that enables the expression and analysis of heterogeneous properties, relations, and interactions on all scales of a complex system in a self-contained manner. Furthermore, to be able to utilize existing network-based methods and models, we derive different representations of

  3. An Efficient Referencing And Sample Positioning System To Investigate Heterogeneous Substances With Combined Microfocused Synchrotron X-ray Techniques

    SciTech Connect

    Spangenberg, Thomas; Goettlicher, Joerg; Steininger, Ralph

    2009-01-29

    A referencing and sample positioning system has been developed to transfer object positions measured with an offline microscope to a synchrotron experimental station. The accuracy should be sufficient to deal with heterogeneous samples on micrometer scale. Together with an online fluorescence mapping visualisation the optical alignment helps to optimize measuring procedures for combined microfocused X-ray techniques.

  4. [Detection of hydroxyl radical in heterogeneous photo-Fenton system using the fluorescence technique and influencing factor study].

    PubMed

    Liu, Ting; You, Hong; Chen, Qi-Wei; Wang, Zhi-Chao

    2009-09-15

    The Fe2O3/TiO2/Al2O3 catalyst was prepared by using TiO2/Al2O3 as carrier and the heterogeneous photo-Fenton system was established in the three-phase fluidized bed. A fluorescence technique was developed for the determination of the hydroxyl radicals (*OH) from the heterogeneous photo-Fenton system, using coumarin as the fluorescence probe. In addition, four main factors, namely pH, H2O2 concentration, catalyst loading and UV light intensity, which could influence the concentration of OH produced during the reaction process, was also discussed. The fluorescence method using coumarin as the fluorescence probe was demonstrated to be capable of detecting *OH generated in heterogeneous photo-Fenton system with veracity and high reproducibility. It was also found that the *OH generated in heterogeneous photo-Fenton system conformed to the zero reaction dynamics in 30 min. Moreover, the pH, H2O2 concentration, catalyst loading and UV light intensity influenced the *OH generated during the reaction process.

  5. A forensics-based approach for assessing incipient heterogeneity of a hydrologic system.

    NASA Astrophysics Data System (ADS)

    Alves Meira Neto, A.; Matos, K. A.; Wang, Y.; Troch, P. A. A.; Chorover, J.; Ferré, T. P. A.

    2015-12-01

    Hydrologic systems are far from being static in time. Therefore, the study of the evolution of natural systems along with the investigation of the interactions between hydrology, geochemistry and geophysics can be highly beneficial for improving hydrologic predictions. In this study, a combined hydrologic, geophysical and geochemical approach is proposed to investigate the incipient heterogeneity in a small hydrologic system subject to intensive flux of water through a period of one year. The Mini-LEO is a sloping metallic lysimeter containing 1 m3 of granular basalt, constructed as a smaller scale version of Landscape Evolution Observatory (LEO) artificial hillslopes. The initially pristine soil inside the Mini-LEO had undergone several cycles of irrigation, which might have changed the internal structure of this system, as observed by both hydrometric data and corroborated by studies pointing out to a rapid weathering of the basaltic soil. A forensic approach was proposed, where the Mini-LEO was systematically excavated for the investigation of its initial signs of hydrologic co-evolution. The lysimeter was sub-divided in voxels, for which 100 undisturbed soil samples and fragmented subsamples were collected for further analysis of soil hydraulic properties (saturated hydraulic conductivity and characteristic curve) as well as geochemical composition (elemental dissolution/accumulations and mineralogical transformations). Additionally, electrical resistivity (ER) measurements at different water content were measured for each sample. The results of this study are manifold: The expected geochemical signature will be used for validating current hydro-geochemical models of the Mini-LEO, and the superposition of the geochemical and hydraulic analysis will serve as discriminatory data for the results of geophysical investigation.

  6. Conformance testing strategies for DICOM protocols in a heterogenous communications system

    NASA Astrophysics Data System (ADS)

    Meyer, Ralph; Hewett, Andrew J.; Cordonnier, Emmanuel; Piqueras, Joachim; Jensch, Peter F.

    1995-05-01

    The goal of the DICOM standard is to define a standard network interface and data model for imaging devices from various vendors. It shall facilitate the development and integration of information systems and picture archiving and communication systems (PACS) in a networked environment. Current activities in Oldenburg, Germany include projects to establish cooperative work applications for radiological purposes, comprising (joined) text, data, signal and image communications, based on narrowband ISDN and ATM communication for regional and Pan European applications. In such a growing and constantly changing environment it is vital to have a solid and implementable plan to bring standards in operation. A communication standard alone cannot ensure interoperability between different vendor implementations. Even DICOM does not specify implementation-specific requirements nor does it specify a testing procedure to assess an implementation's conformance to the standard. The conformance statements defined in the DICOM standard only allow a user to determine which optional components are supported by the implementation. The goal of our work is to build a conformance test suite for DICOM. Conformance testing can aid to simplify and solve problems with multivendor systems. It will check a vendor's implementation against the DICOM standard and state the found subset of functionality. The test suite will be built in respect to the ISO 9646 Standard (OSI-Conformance Testing Methodology and Framework) which is a standard devoted to the subject of conformance testing implementations of Open Systems Interconnection (OSI) standards. For our heterogeneous communication environments we must also consider ISO 9000 - 9004 (quality management and quality assurance) to give the users the confidence in evolving applications.

  7. Clausius' virial vs. Total Potential Energy in a Two-heterogeneous Component System

    NASA Astrophysics Data System (ADS)

    Marmo, C.; Secco, L.

    As underlined in a previous paper (Secco 2000), in a double gravitational bound system in virial equilibrium the Clausius' virial of one subcomponent is not, in general, equal to the total potential energy of the same component as it occurs in a single system without external forces. This is the main reason for the presence, in the cases of two non-coinciding concentric spheroidal subsystems, of a minimum (in absolute value) in the Clausius' virial trend of the inner component B, as its dimension decreases at fixed size and shape of the outer D component, instead of a monotonic absolute increasing trend usually obtained for the total potential energy of the same subsystem. That has been already proved in the case of two heterogeneous homothetic oblate spheroids of spheroidal, similar strata with two power-law density profiles and surely in some cases of non-similar components (Caimmi and Secco 2000). As the minimum appears it leads to the definition of a tidal scale length induced from the outer system on the inner one. What may be the relevance of this scale length in some aspects of the galaxy dynamics we have already investigated (see, e.g., Secco 2001). A new physical insight may be get by looking at the location of this special length inside the plot of the total potential energies of both subsystems separately and of the whole system taking into account also the trend of the antisymmetric residual-energy that is the difference between the tidal and the interaction-energy of each component. References: Caimmi R. and Secco L., 2000, ASP Conf. Ser.Vol.230, in press Secco L., 2000, New Astr. 5, 403, Secco L., 2001, New Astr. 6, 339

  8. Identifying functional zones of denitrification in heterogeneous aquifer systems by numerical simulations - a case study

    NASA Astrophysics Data System (ADS)

    Jang, E.; Kalbacher, T.; He, W.; Shao, H.; Schueth, C.; Kolditz, O.

    2014-12-01

    Nitrate contamination in shallow groundwater is still one of the common problems in many countries. Because of its high solubility and anionic nature, nitrate can easily leach through soil and persist in groundwater for decades. High nitrate concentration has been suggested as a major cause of accelerated eutrophication, methemoglobinemia and gastric cancer. There are several factors influencing the fate of nitrate in groundwater system, which is e.g. distribution of N- sources to soil and groundwater, distribution and amount of reactive substances maintaining denitrification, rate of nitrate degradation and its kinetics, and geological characteristics of the aquifer. Nitrate transport and redox transformation processes are closely linked to complex and spatially distributed physical and chemical interaction, therefore it is difficult to predict and quantify in the field and laboratory experiment. Models can play a key role in elucidation of nitrate reduction pathway in groundwater system and in the design and evaluation of field tests to investigate in situ remediation technologies as well. The goal of the current study is to predict groundwater vulnerability to nitrate, to identify functional zones of denitrification in heterogeneous aquifer systems and to describe the uncertainty of the predictions due to scale effects. For this aim, we developed a kinetic model using multi-component mass transport code OpenGeoSys coupling with IPhreeqc module of the geochemical solver PHREEQC. The developed model included sequential aerobic and nitrate-based respiration, multi-Monod kinetics, multi-species biogeochemical reactions, and geological characteristics of the groundwater aquifer. Moreover water-rock interaction such as secondary mineral precipitation was also included in this model. In this presentation, we focused on the general modelling approach and present the simulation results of nitrate transport simulation in a hypothetical aquifer systems based on data from

  9. PLANETARY-SCALE STRONTIUM ISOTOPIC HETEROGENEITY AND THE AGE OF VOLATILE DEPLETION OF EARLY SOLAR SYSTEM MATERIALS

    SciTech Connect

    Moynier, Frederic; Podosek, Frank A.; Day, James M. D.; Okui, Wataru; Yokoyama, Tetsuya; Bouvier, Audrey; Walker, Richard J. E-mail: fap@levee.wustl.edu E-mail: rjwalker@umd.edu E-mail: tetsuya.yoko@geo.titech.ac.jp

    2012-10-10

    Isotopic anomalies in planetary materials reflect both early solar nebular heterogeneity inherited from presolar stellar sources and processes that generated non-mass-dependent isotopic fractionations. The characterization of isotopic variations in heavy elements among early solar system materials yields important insight into the stellar environment and formation of the solar system, and about initial isotopic ratios relevant to long-term chronological applications. One such heavy element, strontium, is a central element in the geosciences due to wide application of the long-lived {sup 87}Rb-{sup 87}Sr radioactive as a chronometer. We show that the stable isotopes of Sr were heterogeneously distributed at both the mineral scale and the planetary scale in the early solar system, and also that the Sr isotopic heterogeneities correlate with mass-independent oxygen isotope variations, with only CI chondrites plotting outside of this correlation. The correlation implies that most solar system material formed by mixing of at least two isotopically distinct components: a CV-chondrite-like component and an O-chondrite-like component, and possibly a distinct CI-chondrite-like component. The heterogeneous distribution of Sr isotopes may indicate that variations in initial {sup 87}Sr/{sup 86}Sr of early solar system materials reflect isotopic heterogeneity instead of having chronological significance, as interpreted previously. For example, given the differences in {sup 84}Sr/{sup 86}Sr between calcium aluminum inclusions and eucrites ({epsilon}{sup 84}Sr > 2), the difference in age between these materials would be {approx}6 Ma shorter than previously interpreted, placing the Sr chronology in agreement with other long- and short-lived isotope systems, such as U-Pb and Mn-Cr.

  10. Design and implementation of a VoIP broadcasting service over embedded systems in a heterogeneous network environment.

    PubMed

    Leu, Jenq-Shiou; Lin, Wei-Hsiang; Hsieh, Wen-Bin; Lo, Chien-Chih

    2014-01-01

    As the digitization is integrated into daily life, media including video and audio are heavily transferred over the Internet nowadays. Voice-over-Internet Protocol (VoIP), the most popular and mature technology, becomes the focus attracting many researches and investments. However, most of the existing studies focused on a one-to-one communication model in a homogeneous network, instead of one-to-many broadcasting model among diverse embedded devices in a heterogeneous network. In this paper, we present the implementation of a VoIP broadcasting service on the open source-Linphone-in a heterogeneous network environment, including WiFi, 3G, and LAN networks. The proposed system featuring VoIP broadcasting over heterogeneous networks can be integrated with heterogeneous agile devices, such as embedded devices or mobile phones. VoIP broadcasting over heterogeneous networks can be integrated into modern smartphones or other embedded devices; thus when users run in a traditional AM/FM signal unreachable area, they still can receive the broadcast voice through the IP network. Also, comprehensive evaluations are conducted to verify the effectiveness of the proposed implementation. PMID:25300280

  11. Design and Implementation of a VoIP Broadcasting Service over Embedded Systems in a Heterogeneous Network Environment

    PubMed Central

    Lin, Wei-Hsiang; Hsieh, Wen-Bin; Lo, Chien-Chih

    2014-01-01

    As the digitization is integrated into daily life, media including video and audio are heavily transferred over the Internet nowadays. Voice-over-Internet Protocol (VoIP), the most popular and mature technology, becomes the focus attracting many researches and investments. However, most of the existing studies focused on a one-to-one communication model in a homogeneous network, instead of one-to-many broadcasting model among diverse embedded devices in a heterogeneous network. In this paper, we present the implementation of a VoIP broadcasting service on the open source—Linphone—in a heterogeneous network environment, including WiFi, 3G, and LAN networks. The proposed system featuring VoIP broadcasting over heterogeneous networks can be integrated with heterogeneous agile devices, such as embedded devices or mobile phones. VoIP broadcasting over heterogeneous networks can be integrated into modern smartphones or other embedded devices; thus when users run in a traditional AM/FM signal unreachable area, they still can receive the broadcast voice through the IP network. Also, comprehensive evaluations are conducted to verify the effectiveness of the proposed implementation. PMID:25300280

  12. Design and implementation of a VoIP broadcasting service over embedded systems in a heterogeneous network environment.

    PubMed

    Leu, Jenq-Shiou; Lin, Wei-Hsiang; Hsieh, Wen-Bin; Lo, Chien-Chih

    2014-01-01

    As the digitization is integrated into daily life, media including video and audio are heavily transferred over the Internet nowadays. Voice-over-Internet Protocol (VoIP), the most popular and mature technology, becomes the focus attracting many researches and investments. However, most of the existing studies focused on a one-to-one communication model in a homogeneous network, instead of one-to-many broadcasting model among diverse embedded devices in a heterogeneous network. In this paper, we present the implementation of a VoIP broadcasting service on the open source-Linphone-in a heterogeneous network environment, including WiFi, 3G, and LAN networks. The proposed system featuring VoIP broadcasting over heterogeneous networks can be integrated with heterogeneous agile devices, such as embedded devices or mobile phones. VoIP broadcasting over heterogeneous networks can be integrated into modern smartphones or other embedded devices; thus when users run in a traditional AM/FM signal unreachable area, they still can receive the broadcast voice through the IP network. Also, comprehensive evaluations are conducted to verify the effectiveness of the proposed implementation.

  13. Necessary and sufficient condition for average consensus of networked multi-agent systems with heterogeneous time delays

    NASA Astrophysics Data System (ADS)

    Sakurama, Kazunori; Nakano, Kazushi

    2015-04-01

    This paper deals with an average-consensus problem of networked multi-agent systems with heterogeneous time delays. First, a necessary and sufficient condition is derived for multi-agent systems to achieve average consensus. This condition is represented in the form of an algebraic condition by using the delay-transition and the delay-weighted Laplacians. Second, a performance criterion is introduced to evaluate multi-agent systems that do not achieve average consensus. The criterion is represented in terms of the norms with respect to the above Laplacians. These results imply that the introduced Laplacians play important roles in analysing multi-agent systems with heterogeneous time delays. The validity of the analysis results is demonstrated by simulations with six-agent systems.

  14. A unique dosing system for the production of OH under high vacuum for the study of environmental heterogeneous reactions

    SciTech Connect

    Brown, Matthew A.; Johanek, Viktor; Hemminger, John C.

    2008-02-15

    A unique dosing system for the production of hydroxyl radicals under high vacuum for the study of environmental heterogeneous reactions is described. Hydroxyl radicals are produced by the photodissociation of a hydrogen peroxide aqueous gas mixture with 254 nm radiation according to the reaction H{sub 2}O{sub 2}+h{nu} (254 nm){yields}OH+OH. Under the conditions of the current design, 0.6% conversion of hydrogen peroxide is expected yielding a hydroxyl number density on the order of 10{sup 10} molecules/cm{sup 3}. The flux distribution of the dosing system is calculated using a Monte Carlo simulation method and compared with the experimentally determined results. The performance of this unique hydroxyl dosing system is demonstrated for the heterogeneous reaction with a solid surface of potassium iodide. Coupling of the hydroxyl radical dosing system to a quantitative surface analysis system should help provide molecular level insight into detailed reaction mechanisms.

  15. Local heterogeneities in cardiac systems suppress turbulence by generating multi-armed rotors

    NASA Astrophysics Data System (ADS)

    Zhang, Zhihui; Steinbock, Oliver

    2016-05-01

    Ventricular fibrillation is an extremely dangerous cardiac arrhythmia that is linked to rotating waves of electric activity and chaotically moving vortex lines. These filaments can pin to insulating, cylindrical heterogeneities which swiftly become the new rotation backbone of the local wave field. For thin cylinders, the stabilized rotation is sufficiently fast to repel the free segments of the turbulent filament tangle and annihilate them at the system boundaries. The resulting global wave pattern is periodic and highly ordered. Our cardiac simulations show that also thicker cylinders can establish analogous forms of tachycardia. This process occurs through the spontaneous formation of pinned multi-armed vortices. The observed number of wave arms N depends on the cylinder radius and is associated to stability windows that for N = 2, 3 partially overlap. For N = 1, 2, we find a small gap in which the turbulence is removed but the pinned rotor shows complex temporal dynamics. The relevance of our findings to human cardiology are discussed in the context of vortex pinning to more complex-shaped anatomical features and remodeled myocardium.

  16. Determination of migration pathways of DNAPL and dissolved phase volatile organic compounds in heterogeneous aquifer systems

    SciTech Connect

    Lamb, B. ); Prucha, R.

    1993-10-01

    Before an effective ground-water extraction system can be designed, it is essential to determine the distribution of chemicals of concern in ground-water and preferential pathways for chemical migration. At the study site, determining the chemical migration pathways and spatial distribution of chemicals are complicated by the presence of halogenated volatile organic compounds (VOCs) and dense nonaqueous phase liquids (DNAPL) coupled with the heterogeneous nature of the aquifer. DNAPL is denser than ground water and therefore sinks due to gravity while the dissolved components tend to be dominated by regional ground-water advective flow. The study area is a former industrial site. The aquifer is a low permeability unit with thin lenses of sandy material. Dissolved phase chemicals preferentially migrate in these sand units. To determine pathways for the migration of chemicals both laterally and horizontally, borehole lithologic data, hydraulic data, and chemical data were synthesized into a computer database and used as input for graphical illustrations using computer aided drafting (CAD). The CAD software was also used to provide the basis for 2-D and 3-D visualization to interpret field data which aided in development of a detailed conceptual site model and in construction of a numerical ground-water flow model for the site.

  17. Large Scale Tissue Morphogenesis Simulation on Heterogenous Systems Based on a Flexible Biomechanical Cell Model.

    PubMed

    Jeannin-Girardon, Anne; Ballet, Pascal; Rodin, Vincent

    2015-01-01

    The complexity of biological tissue morphogenesis makes in silico simulations of such system very interesting in order to gain a better understanding of the underlying mechanisms ruling the development of multicellular tissues. This complexity is mainly due to two elements: firstly, biological tissues comprise a large amount of cells; secondly, these cells exhibit complex interactions and behaviors. To address these two issues, we propose two tools: the first one is a virtual cell model that comprise two main elements: firstly, a mechanical structure (membrane, cytoskeleton, and cortex) and secondly, the main behaviors exhibited by biological cells, i.e., mitosis, growth, differentiation, molecule consumption, and production as well as the consideration of the physical constraints issued from the environment. An artificial chemistry is also included in the model. This virtual cell model is coupled to an agent-based formalism. The second tool is a simulator that relies on the OpenCL framework. It allows efficient parallel simulations on heterogenous devices such as micro-processors or graphics processors. We present two case studies validating the implementation of our model in our simulator: cellular proliferation controlled by cell signalling and limb growth in a virtual organism. PMID:26451816

  18. Heterogeneity and phenotypic plasticity of glial cells in the mammalian enteric nervous system.

    PubMed

    Boesmans, Werend; Lasrado, Reena; Vanden Berghe, Pieter; Pachnis, Vassilis

    2015-02-01

    Enteric glial cells are vital for the autonomic control of gastrointestinal homeostasis by the enteric nervous system. Several different functions have been assigned to enteric glial cells but whether these are performed by specialized subtypes with a distinctive phenotype and function remains elusive. We used Mosaic Analysis with Double Markers and inducible lineage tracing to characterize the morphology and dynamic molecular marker expression of enteric GLIA in the myenteric plexus. Functional analysis in individually identified enteric glia was performed by Ca(2+) imaging. Our experiments have identified four morphologically distinct subpopulations of enteric glia in the gastrointestinal tract of adult mice. Marker expression analysis showed that the majority of glia in the myenteric plexus co-express glial fibrillary acidic protein (GFAP), S100β, and Sox10. However, a considerable fraction (up to 80%) of glia outside the myenteric ganglia, did not label for these markers. Lineage tracing experiments suggest that these alternative combinations of markers reflect dynamic gene regulation rather than lineage restrictions. At the functional level, the three myenteric glia subtypes can be distinguished by their differential response to adenosine triphosphate. Together, our studies reveal extensive heterogeneity and phenotypic plasticity of enteric glial cells and set a framework for further investigations aimed at deciphering their role in digestive function and disease.

  19. Multivariate analysis of the heterogeneous geochemical processes controlling arsenic enrichment in a shallow groundwater system.

    PubMed

    Huang, Shuangbing; Liu, Changrong; Wang, Yanxin; Zhan, Hongbin

    2014-01-01

    The effects of various geochemical processes on arsenic enrichment in a high-arsenic aquifer at Jianghan Plain in Central China were investigated using multivariate models developed from combined adaptive neuro-fuzzy inference system (ANFIS) and multiple linear regression (MLR). The results indicated that the optimum variable group for the AFNIS model consisted of bicarbonate, ammonium, phosphorus, iron, manganese, fluorescence index, pH, and siderite saturation. These data suggest that reductive dissolution of iron/manganese oxides, phosphate-competitive adsorption, pH-dependent desorption, and siderite precipitation could integrally affect arsenic concentration. Analysis of the MLR models indicated that reductive dissolution of iron(III) was primarily responsible for arsenic mobilization in groundwaters with low arsenic concentration. By contrast, for groundwaters with high arsenic concentration (i.e., > 170 μg/L), reductive dissolution of iron oxides approached a dynamic equilibrium. The desorption effects from phosphate-competitive adsorption and the increase in pH exhibited arsenic enrichment superior to that caused by iron(III) reductive dissolution as the groundwater chemistry evolved. The inhibition effect of siderite precipitation on arsenic mobilization was expected to exist in groundwater that was highly saturated with siderite. The results suggest an evolutionary dominance of specific geochemical process over other factors controlling arsenic concentration, which presented a heterogeneous distribution in aquifers. Supplemental materials are available for this article. Go to the publisher's online edition of the Journal of Environmental Science and Health, Part A, to view the supplemental file. PMID:24345245

  20. Large Scale Tissue Morphogenesis Simulation on Heterogenous Systems Based on a Flexible Biomechanical Cell Model.

    PubMed

    Jeannin-Girardon, Anne; Ballet, Pascal; Rodin, Vincent

    2015-01-01

    The complexity of biological tissue morphogenesis makes in silico simulations of such system very interesting in order to gain a better understanding of the underlying mechanisms ruling the development of multicellular tissues. This complexity is mainly due to two elements: firstly, biological tissues comprise a large amount of cells; secondly, these cells exhibit complex interactions and behaviors. To address these two issues, we propose two tools: the first one is a virtual cell model that comprise two main elements: firstly, a mechanical structure (membrane, cytoskeleton, and cortex) and secondly, the main behaviors exhibited by biological cells, i.e., mitosis, growth, differentiation, molecule consumption, and production as well as the consideration of the physical constraints issued from the environment. An artificial chemistry is also included in the model. This virtual cell model is coupled to an agent-based formalism. The second tool is a simulator that relies on the OpenCL framework. It allows efficient parallel simulations on heterogenous devices such as micro-processors or graphics processors. We present two case studies validating the implementation of our model in our simulator: cellular proliferation controlled by cell signalling and limb growth in a virtual organism.

  1. Heterogeneous generation of new cells in the adult echinoderm nervous system

    PubMed Central

    Mashanov, Vladimir S.; Zueva, Olga R.; García-Arrarás, José E.

    2015-01-01

    Adult neurogenesis, generation of new functional cells in the mature central nervous system (CNS), has been documented in a number of diverse organisms, ranging from humans to invertebrates. However, the origin and evolution of this phenomenon is still poorly understood for many of the key phylogenetic groups. Echinoderms are one such phylum, positioned as a sister group to chordates within the monophyletic clade Deuterostomia. They are well known for the ability of their adult organs, including the CNS, to completely regenerate after injury. Nothing is known, however, about production of new cells in the nervous tissue under normal physiological conditions in these animals. In this study, we show that new cells are continuously generated in the mature radial nerve cord (RNC) of the sea cucumber Holothuria glaberrima. Importantly, this neurogenic activity is not evenly distributed, but is significantly more extensive in the lateral regions of the RNC than along the midline. Some of the new cells generated in the apical region of the ectoneural neuroepithelium leave their place of origin and migrate basally to populate the neural parenchyma. Gene expression analysis showed that generation of new cells in the adult sea cucumber CNS is associated with transcriptional activity of genes known to be involved in regulation of various aspects of neurogenesis in other animals. Further analysis of one of those genes, the transcription factor Myc, showed that it is expressed, in some, but not all radial glial cells, suggesting heterogeneity of this CNS progenitor cell population in echinoderms. PMID:26441553

  2. The tsunami service bus, an integration platform for heterogeneous sensor systems

    NASA Astrophysics Data System (ADS)

    Haener, R.; Waechter, J.; Kriegel, U.; Fleischer, J.; Mueller, S.

    2009-04-01

    components remain unchanged, components can be maintained and evolved independently on each other and service functionality as a whole can be reused. In GITEWS the functional integration pattern was adopted by applying the principles of an Enterprise Service Bus (ESB) as a backbone. Four services provided by the so called Tsunami Service Bus (TSB) which are essential for early warning systems are realized compliant to services specified within the Sensor Web Enablement (SWE) initiative of the Open Geospatial Consortium (OGC). 3. ARCHITECTURE The integration platform was developed to access proprietary, heterogeneous sensor data and to provide them in a uniform manner for further use. Its core, the TSB provides both a messaging-backbone and -interfaces on the basis of a Java Messaging Service (JMS). The logical architecture of GITEWS consists of four independent layers: • A resource layer where physical or virtual sensors as well as data or model storages provide relevant measurement-, event- and analysis-data: Utilizable for the TSB are any kind of data. In addition to sensors databases, model data and processing applications are adopted. SWE specifies encoding both to access and to describe these data in a comprehensive way: 1. Sensor Model Language (SensorML): Standardized description of sensors and sensor data 2. Observations and Measurements (O&M): Model and encoding of sensor measurements • A service layer to collect and conduct data from heterogeneous and proprietary resources and provide them via standardized interfaces: The TSB enables interaction with sensors via the following services: 1. Sensor Observation Service (SOS): Standardized access to sensor data 2. Sensor Planning Service (SPS): Controlling of sensors and sensor networks 3. Sensor Alert Service (SAS): Active sending of data if defined events occur 4. Web Notification Service (WNS): Conduction of asynchronous dialogues between services • An orchestration layer where atomic services are composed and

  3. Control of synchronization and spiking regularity by heterogenous aperiodic high-frequency signal in coupled excitable systems

    NASA Astrophysics Data System (ADS)

    Qin, Ying-Mei; Wang, Jiang; Men, Cong; Chan, Wai-Lok; Wei, Xi-Le; Deng, Bin

    2013-10-01

    This paper investigates the synchronization and spiking regularity induced by heterogenous aperiodic (HA) signal in coupled excitable FitzHugh-Nagumo systems. We found new nontrivial effects of couplings and HA signals on the firing regularity and synchronization in coupled excitable systems without a periodic external driving. The phenomenon is similar to array enhanced coherence resonance (AECR), and it is shown that AECR-type behavior is not limited to systems driven by noises. It implies that the HA signal may be beneficial for the brain function, which is similar to the role of noise. Furthermore, it is also found that the mean frequencies, the amplitudes and the heterogeneity of HA stimuli can serve as control parameters in modulating spiking regularity and synchronization in coupled excitable systems. These results may be significant for the control of the synchronized firing of the brain in neural diseases like epilepsy.

  4. Development of a phantom to validate high-dose-rate brachytherapy treatment planning systems with heterogeneous algorithms

    SciTech Connect

    Moura, Eduardo S.; Rostelato, Maria Elisa C. M.; Zeituni, Carlos A.

    2015-04-15

    Purpose: This work presents the development of a phantom to verify the treatment planning system (TPS) algorithms used for high-dose-rate (HDR) brachytherapy. It is designed to measure the relative dose in a heterogeneous media. The experimental details used, simulation methods, and comparisons with a commercial TPS are also provided. Methods: To simulate heterogeneous conditions, four materials were used: Virtual Water™ (VM), BR50/50™, cork, and aluminum. The materials were arranged in 11 heterogeneity configurations. Three dosimeters were used to measure the relative response from a HDR {sup 192}Ir source: TLD-100™, Gafchromic{sup ®} EBT3 film, and an Exradin™ A1SL ionization chamber. To compare the results from the experimental measurements, the various configurations were modeled in the PENELOPE/penEasy Monte Carlo code. Images of each setup geometry were acquired from a CT scanner and imported into BrachyVision™ TPS software, which includes a grid-based Boltzmann solver Acuros™. The results of the measurements performed in the heterogeneous setups were normalized to the dose values measured in the homogeneous Virtual Water™ setup and the respective differences due to the heterogeneities were considered. Additionally, dose values calculated based on the American Association of Physicists in Medicine-Task Group 43 formalism were compared to dose values calculated with the Acuros™ algorithm in the phantom. Calculated doses were compared at the same points, where measurements have been performed. Results: Differences in the relative response as high as 11.5% were found from the homogeneous setup when the heterogeneous materials were inserted into the experimental phantom. The aluminum and cork materials produced larger differences than the plastic materials, with the BR50/50™ material producing results similar to the Virtual Water™ results. Our experimental methods agree with the PENELOPE/penEasy simulations for most setups and dosimeters. The

  5. Electronic and Vibrational Properties of Low-Dimensional Heterogeneous Systems: Materials and Device Perspectives

    NASA Astrophysics Data System (ADS)

    Neupane, Mahesh Raj

    Due to the aggressive miniaturization of memory and logic devices, the current technologies based on silicon have nearly reached their ultimate size limit. One method to maintain the trend in device scaling observed by Moore's law is to create a heterostructure from existing materials and utilize the underlying electronic and optical properties. Another radical approach is the conceptualization of a new device design paradigm. The central objective of this thesis is to use both of these approaches to address issues associated with the aggressive scaling of memory and logic devices such as leakage current, leakage power, and minimizing gate oxide thickness and threshold voltage. In the first part of the dissertation, an atomistic, empirical tight binding method was used to perform a systematic investigation of the effect of physical (shape and size), and material dependent (heterogenity and strain) properties on the device related electronic and optical properties of the Germanium (Ge)/Silicon (Si) nanocrystal (NC) or quantum dot (QD). The device parameters pertaining to Ge-core/Si-shell NC-based floating gate memory and optical devices such as confinement energy, retention lifetimes and optical intensities are captured and analyzed. For both the memory and optical device applications, regardless of the shape and size, the Ge-core is found to play an important role in modifying the confinement energy and carrier dynamics. However, the variation in the thickness of outer Si-shell layer had no or minimal effect on the overall device parameters. In the second part of the dissertation, we present a systematic study of the effect of atomistic heterogeneity on the vibrational properties of quasi-2D systems and recently discovered 2D materials such as graphene, while investigating their applicabilities in future devices applications. At first, we investigate the vibrational properties of an experimentally observed misoriented bilayer graphene (MBG) system, a

  6. Climate change simulations predict altered biotic response in a thermally heterogeneous stream system.

    PubMed

    Westhoff, Jacob T; Paukert, Craig P

    2014-01-01

    Climate change is predicted to increase water temperatures in many lotic systems, but little is known about how changes in air temperature affect lotic systems heavily influenced by groundwater. Our objectives were to document spatial variation in temperature for spring-fed Ozark streams in Southern Missouri USA, create a spatially explicit model of mean daily water temperature, and use downscaled climate models to predict the number of days meeting suitable stream temperature for three aquatic species of concern to conservation and management. Longitudinal temperature transects and stationary temperature loggers were used in the Current and Jacks Fork Rivers during 2012 to determine spatial and temporal variability of water temperature. Groundwater spring influence affected river water temperatures in both winter and summer, but springs that contributed less than 5% of the main stem discharge did not affect river temperatures beyond a few hundred meters downstream. A multiple regression model using variables related to season, mean daily air temperature, and a spatial influence factor (metric to account for groundwater influence) was a strong predictor of mean daily water temperature (r2 = 0.98; RMSE = 0.82). Data from two downscaled climate simulations under the A2 emissions scenario were used to predict daily water temperatures for time steps of 1995, 2040, 2060, and 2080. By 2080, peak numbers of optimal growth temperature days for smallmouth bass are expected to shift to areas with more spring influence, largemouth bass are expected to experience more optimal growth days (21-317% increase) regardless of spring influence, and Ozark hellbenders may experience a reduction in the number of optimal growth days in areas with the highest spring influence. Our results provide a framework for assessing fine-scale (10 s m) thermal heterogeneity and predict shifts in thermal conditions at the watershed and reach scale. PMID:25356982

  7. Climate change simulations predict altered biotic response in a thermally heterogeneous stream system.

    PubMed

    Westhoff, Jacob T; Paukert, Craig P

    2014-01-01

    Climate change is predicted to increase water temperatures in many lotic systems, but little is known about how changes in air temperature affect lotic systems heavily influenced by groundwater. Our objectives were to document spatial variation in temperature for spring-fed Ozark streams in Southern Missouri USA, create a spatially explicit model of mean daily water temperature, and use downscaled climate models to predict the number of days meeting suitable stream temperature for three aquatic species of concern to conservation and management. Longitudinal temperature transects and stationary temperature loggers were used in the Current and Jacks Fork Rivers during 2012 to determine spatial and temporal variability of water temperature. Groundwater spring influence affected river water temperatures in both winter and summer, but springs that contributed less than 5% of the main stem discharge did not affect river temperatures beyond a few hundred meters downstream. A multiple regression model using variables related to season, mean daily air temperature, and a spatial influence factor (metric to account for groundwater influence) was a strong predictor of mean daily water temperature (r2 = 0.98; RMSE = 0.82). Data from two downscaled climate simulations under the A2 emissions scenario were used to predict daily water temperatures for time steps of 1995, 2040, 2060, and 2080. By 2080, peak numbers of optimal growth temperature days for smallmouth bass are expected to shift to areas with more spring influence, largemouth bass are expected to experience more optimal growth days (21-317% increase) regardless of spring influence, and Ozark hellbenders may experience a reduction in the number of optimal growth days in areas with the highest spring influence. Our results provide a framework for assessing fine-scale (10 s m) thermal heterogeneity and predict shifts in thermal conditions at the watershed and reach scale.

  8. Climate Change Simulations Predict Altered Biotic Response in a Thermally Heterogeneous Stream System

    PubMed Central

    Westhoff, Jacob T.; Paukert, Craig P.

    2014-01-01

    Climate change is predicted to increase water temperatures in many lotic systems, but little is known about how changes in air temperature affect lotic systems heavily influenced by groundwater. Our objectives were to document spatial variation in temperature for spring-fed Ozark streams in Southern Missouri USA, create a spatially explicit model of mean daily water temperature, and use downscaled climate models to predict the number of days meeting suitable stream temperature for three aquatic species of concern to conservation and management. Longitudinal temperature transects and stationary temperature loggers were used in the Current and Jacks Fork Rivers during 2012 to determine spatial and temporal variability of water temperature. Groundwater spring influence affected river water temperatures in both winter and summer, but springs that contributed less than 5% of the main stem discharge did not affect river temperatures beyond a few hundred meters downstream. A multiple regression model using variables related to season, mean daily air temperature, and a spatial influence factor (metric to account for groundwater influence) was a strong predictor of mean daily water temperature (r2 = 0.98; RMSE = 0.82). Data from two downscaled climate simulations under the A2 emissions scenario were used to predict daily water temperatures for time steps of 1995, 2040, 2060, and 2080. By 2080, peak numbers of optimal growth temperature days for smallmouth bass are expected to shift to areas with more spring influence, largemouth bass are expected to experience more optimal growth days (21 – 317% increase) regardless of spring influence, and Ozark hellbenders may experience a reduction in the number of optimal growth days in areas with the highest spring influence. Our results provide a framework for assessing fine-scale (10 s m) thermal heterogeneity and predict shifts in thermal conditions at the watershed and reach scale. PMID:25356982

  9. Nanoscale zero-valent iron/AC as heterogeneous Fenton catalysts in three-dimensional electrode system.

    PubMed

    Zhang, Chao; Zhou, Lei; Yang, Jie; Yu, Xinmin; Jiang, Yonghai; Zhou, Minghua

    2014-01-01

    In the present work, nanoscale zero-valent iron/activated carbon (NZVI/AC) was investigated as heterogeneous Fenton catalyst in three-dimensional (3D) electrode system for methyl orange (MO) degradation. Some important operating parameters such as cathodic potential, pH, and O₂ flow rate were investigated, exhibiting good decolorization. The mineralization of MO was significantly improved by 20-35% compared to two-dimensional (2D) AC system at the optimum conditions. Although the TOC removal of AC was higher than NZVI/AC due to its good adsorption capacity initially, heterogeneous Fenton catalysis played a more and more important roles in the following test. After eight runs, NZVI/AC still exhibited excellent catalytic properties with low iron leaching. Further, a relatively comprehensive mechanism of NZVI/AC as particle electrodes in 3D system was proposed.

  10. Electron localization in a mixed-valence diniobium benzene complex

    DOE PAGES

    Gianetti, Thomas L.; Nocton, Grégory; Minasian, Stefan G.; Kaltsoyannis, Nikolas; Kilcoyne, A. L. David; Kozimor, Stosh A.; Shuh, David K.; Tyliszczak, Tolek; Bergman, Robert G.; Arnold, John

    2014-11-11

    Reaction of the neutral diniobium benzene complex {[Nb(BDI)NtBu]2(μ-C6H6)} (BDI = N,N'-diisopropylbenzene-β-diketiminate) with Ag[B(C6F5)4] results in a single electron oxidation to produce a cationic diniobium arene complex, {[Nb(BDI)NtBu]2(μ-C6H6)}{B(C6F5)4}. Investigation of the solid state and solution phase structure using single-crystal X-ray diffraction, cyclic voltammetry, magnetic susceptibility, and multinuclear NMR spectroscopy indicates that the oxidation results in an asymmetric molecule with two chemically inequivalent Nb atoms. Further characterization using density functional theory (DFT) calculations, UV-visible, Nb L3,2-edge X-ray absorption near-edge structure (XANES), and EPR spectroscopies supports assignment of a diniobium complex, in which one Nb atom carries a single unpaired electron that ismore » not largely delocalized on the second Nb atom. During the oxidative transformation, one electron is removed from the δ-bonding HOMO, which causes a destabilization of the molecule and formation of an asymmetric product. Subsequent reactivity studies indicate that the oxidized product allows access to metal-based chemistry with substrates that did not exhibit reactivity with the starting neutral complex.« less

  11. Electron localization in a mixed-valence diniobium benzene complex

    SciTech Connect

    Gianetti, Thomas L.; Nocton, Grégory; Minasian, Stefan G.; Kaltsoyannis, Nikolas; Kilcoyne, A. L. David; Kozimor, Stosh A.; Shuh, David K.; Tyliszczak, Tolek; Bergman, Robert G.; Arnold, John

    2014-11-11

    Reaction of the neutral diniobium benzene complex {[Nb(BDI)NtBu]2(μ-C6H6)} (BDI = N,N'-diisopropylbenzene-β-diketiminate) with Ag[B(C6F5)4] results in a single electron oxidation to produce a cationic diniobium arene complex, {[Nb(BDI)NtBu]2(μ-C6H6)}{B(C6F5)4}. Investigation of the solid state and solution phase structure using single-crystal X-ray diffraction, cyclic voltammetry, magnetic susceptibility, and multinuclear NMR spectroscopy indicates that the oxidation results in an asymmetric molecule with two chemically inequivalent Nb atoms. Further characterization using density functional theory (DFT) calculations, UV-visible, Nb L3,2-edge X-ray absorption near-edge structure (XANES), and EPR spectroscopies supports assignment of a diniobium complex, in which one Nb atom carries a single unpaired electron that is not largely delocalized on the second Nb atom. During the oxidative transformation, one electron is removed from the δ-bonding HOMO, which causes a destabilization of the molecule and formation of an asymmetric product. Subsequent reactivity studies indicate that the oxidized product allows access to metal-based chemistry with substrates that did not exhibit reactivity with the starting neutral complex.

  12. Preparation, Characterization, and Selectivity Study of Mixed-Valence Sulfites

    ERIC Educational Resources Information Center

    Silva, Luciana A.; de Andrade, Jailson B.

    2010-01-01

    A project involving the synthesis of an isomorphic double sulfite series and characterization by classical inorganic chemical analyses is described. The project is performed by upper-level undergraduate students in the laboratory. This compound series is suitable for examining several chemical concepts and analytical techniques in inorganic…

  13. An investigation of interference coordination in heterogeneous network for LTE-Advanced systems

    NASA Astrophysics Data System (ADS)

    Hasan, M. K.; Ismail, A. F.; H, Aisha-Hassan A.; Abdullah, Khaizuran; Ramli, H. A. M.

    2013-12-01

    The novel "femtocell" in Heterogeneous Network (HetNet) for LTE-Advanced (LTE-A) set-up will allow Malaysian wireless telecommunication operators (Maxis, Celcom, Digi, U-Mobile, P1, YTL and etc2.) to extend connectivity coverage where access would otherwise be limited or unavailable, particularly indoors of large building complexes. A femtocell is a small-sized cellular base station that encompasses all the functionality of a typical station. It therefore allows a simpler and self-contained deployment including private residences. For the Malaysian service providers, the main attractions of femtocell usage are the improvements to both coverage and capacity. The operators can provide a better service to end-users in turn reduce much of the agitations and complaints. There will be opportunity for new services at reduced cost. In addition, the operator not only benefits from the improved capacity and coverage but also can reduce both capital expenditure and operating expense i.e. alternative to brand new base station or macrocell installation. Interference is a key issue associated with femtocell development. There are a large number of issues associated with interference all of which need to be investigated, identified, quantified and solved. This is to ensure that the deployment of any femtocells will take place successfully. Among the most critical challenges in femtocell deployment is the interference between femtocell-to-macrocell and femtocell-to-femtocell in HetNets. In this paper, all proposed methods and algorithms will be investigated in the OFDMA femtocell system considering HetNet scenarios for LTE-A.

  14. Heterogeneous Distribution of 26Al at the Birth of the Solar System

    NASA Astrophysics Data System (ADS)

    Makide, Kentaro; Nagashima, Kazuhide; Krot, Alexander N.; Huss, Gary R.; Ciesla, Fred J.; Hellebrand, Eric; Gaidos, Eric; Yang, Le

    2011-06-01

    It is believed that 26Al, a short-lived (t 1/2 = 0.73 Ma) and now extinct radionuclide, was uniformly distributed in the nascent solar system (SS) with the initial 26Al/27Al ratio of ~5.2 × 10-5, suggesting an external, stellar origin rather than local, solar source. However, the stellar source of 26Al and the manner in which it was injected into the SS remain controversial: the 26Al could have been produced by an asymptotic giant branch star, a supernova, or a Wolf-Rayet star and injected either into the protosolar molecular cloud, protosolar cloud core, or protoplanetary disk. Corundum (Al2O3) is predicted to be the first condensate from a cooling gas of solar composition. Here we show that micron-sized corundum condensates from 16O-rich (Δ17O ~ -25‰) gas of solar composition recorded heterogeneous distribution of 26Al at the birth of the SS: the inferred initial 26Al/27Al ratio ranges from ~6.5×10-5 to <2×10-6 52% of corundum grains measured are 26Al-poor. Abundant 26Al-poor, 16O-rich refractory objects include grossite- and hibonite-rich calcium-aluminum-rich inclusions (CAIs) in CH (high metal abundance and high iron concentration) chondrites, platy hibonite crystals in CM (Mighei-like) chondrites, and CAIs with fractionation and unidentified nuclear effects CAIs chondrites. Considering the apparently early and short duration (<0.3 Ma) of condensation of refractory 16O-rich solids in the SS, we infer that 26Al was injected into the collapsing protosolar molecular cloud and later homogenized in the protoplanetary disk. The apparent lack of correlation between 26Al abundance and O-isotope composition of corundum grains constrains the stellar source of 26Al in the SS.

  15. Investigation of interaction between the Pt(II) ions and aminosilane-modified silica surface in heterogeneous system

    NASA Astrophysics Data System (ADS)

    Nowicki, Waldemar; Gąsowska, Anna; Kirszensztejn, Piotr

    2016-05-01

    UV-vis spectroscopy measurements confirmed the reaction in heterogeneous system between Pt(II) ions and ethylenediamine type ligand, n-(2-aminoethyl)-3-aminopropyl-trimethoxysilane, immobilized at the silica surface. The formation of complexes is a consequence of interaction between the amine groups from the ligand grafted onto SiO2 and ions of platinum. A potentiometric titration technique was to determine the stability constants of complexes of Pt(II) with immobilized insoluble ligand (SG-L), on the silica gel. The results show the formation of three surface complexes of the same type (PtHSG-L, Pt(HSG-L)2, PtSG-L) with SG-L ligand, in a wide range of pH for different Debye length. The concentration distribution of the complexes in a heterogeneous system is evaluated.

  16. A system for simulating shared memory in heterogeneous distributed-memory networks with specialization for robotics applications

    SciTech Connect

    Jones, J.P.; Bangs, A.L.; Butler, P.L.

    1991-01-01

    Hetero Helix is a programming environment which simulates shared memory on a heterogeneous network of distributed-memory computers. The machines in the network may vary with respect to their native operating systems and internal representation of numbers. Hetero Helix presents a simple programming model to developers, and also considers the needs of designers, system integrators, and maintainers. The key software technology underlying Hetero Helix is the use of a compiler'' which analyzes the data structures in shared memory and automatically generates code which translates data representations from the format native to each machine into a common format, and vice versa. The design of Hetero Helix was motivated in particular by the requirements of robotics applications. Hetero Helix has been used successfully in an integration effort involving 27 CPUs in a heterogeneous network and a body of software totaling roughly 100,00 lines of code. 25 refs., 6 figs.

  17. The Smart Floor: How a Public-Private Partnership co-developed a heterogeneous healthcare technology system.

    PubMed

    Brodersen, Søsser; Lindegaard, Hanne

    2015-01-01

    Currently, a wide variety of healthcare technologies are being implemented in private homes, hospitals, nursing homes, etc. with the triple aim of improving people's health, improving the quality of care, and reducing costs related to healthcare services. In this chapter, we discuss how different actors in a public-private partnership co-developed a heterogeneous system around the Smart Floor to ensure that both new healthcare practices and residents' routines were inscribed into the new healthcare technology. We argue that implementing the Smart Floor was not just a question of buying a technology and integrating it during construction-it required co-development with the healthcare staff. The floor is more than a technology placed under the floor surface in a resident's apartment; rather, it is a heterogeneous network of human and non-human actors communicating with each other. In this chapter, we illustrate how the heterogeneous technological system was co-developed and redesigned during knowledge sharing processes with companies, lead-users, and healthcare staff. We also discuss how care practices have changed as a result of the Smart Floor system. In particular, healthcare staff members no longer feel a need to disturb elderly residents with routine in-person checks. Domesticating the technologies for different groups of actors required not only coordinating communication among sensors, the interface, the portable nurse call (smartphones), and alarms, but also accepting the use of surveillance technology. PMID:26249197

  18. Statistical analysis of liquid seepage in partially saturated heterogeneous fracture systems

    SciTech Connect

    Liou, T.S.

    1999-12-01

    Field evidence suggests that water flow in unsaturated fracture systems may occur along fast preferential flow paths. However, conventional macroscale continuum approaches generally predict the downward migration of water as a spatially uniform wetting front subjected to strong inhibition into the partially saturated rock matrix. One possible cause of this discrepancy may be the spatially random geometry of the fracture surfaces, and hence, the irregular fracture aperture. Therefore, a numerical model was developed in this study to investigate the effects of geometric features of natural rock fractures on liquid seepage and solute transport in 2-D planar fractures under isothermal, partially saturated conditions. The fractures were conceptualized as 2-D heterogeneous porous media that are characterized by their spatially correlated permeability fields. A statistical simulator, which uses a simulated annealing (SA) algorithm, was employed to generate synthetic permeability fields. Hypothesized geometric features that are expected to be relevant for seepage behavior, such as spatially correlated asperity contacts, were considered in the SA algorithm. Most importantly, a new perturbation mechanism for SA was developed in order to consider specifically the spatial correlation near conditioning asperity contacts. Numerical simulations of fluid flow and solute transport were then performed in these synthetic fractures by the flow simulator TOUGH2, assuming that the effects of matrix permeability, gas phase pressure, capillary/permeability hysteresis, and molecular diffusion can be neglected. Results of flow simulation showed that liquid seepage in partially saturated fractures is characterized by localized preferential flow, along with bypassing, funneling, and localized ponding. Seepage pattern is dominated by the fraction of asperity contracts, and their shape, size, and spatial correlation. However, the correlation structure of permeability field is less important

  19. HETEROGENEOUS DISTRIBUTION OF {sup 26}Al AT THE BIRTH OF THE SOLAR SYSTEM

    SciTech Connect

    Makide, Kentaro; Nagashima, Kazuhide; Krot, Alexander N.; Huss, Gary R.; Ciesla, Fred J.; Yang, Le; Hellebrand, Eric; Gaidos, Eric

    2011-06-01

    It is believed that {sup 26}Al, a short-lived (t{sub 1/2} = 0.73 Ma) and now extinct radionuclide, was uniformly distributed in the nascent solar system (SS) with the initial {sup 26}Al/{sup 27}Al ratio of {approx}5.2 x 10{sup -5}, suggesting an external, stellar origin rather than local, solar source. However, the stellar source of {sup 26}Al and the manner in which it was injected into the SS remain controversial: the {sup 26}Al could have been produced by an asymptotic giant branch star, a supernova, or a Wolf-Rayet star and injected either into the protosolar molecular cloud, protosolar cloud core, or protoplanetary disk. Corundum (Al{sub 2}O{sub 3}) is predicted to be the first condensate from a cooling gas of solar composition. Here we show that micron-sized corundum condensates from {sup 16}O-rich ({Delta}{sup 17}O {approx} -25 per mille ) gas of solar composition recorded heterogeneous distribution of {sup 26}Al at the birth of the SS: the inferred initial {sup 26}Al/{sup 27}Al ratio ranges from {approx}6.5x10{sup -5} to <2x10{sup -6}; 52% of corundum grains measured are {sup 26}Al-poor. Abundant {sup 26}Al-poor, {sup 16}O-rich refractory objects include grossite- and hibonite-rich calcium-aluminum-rich inclusions (CAIs) in CH (high metal abundance and high iron concentration) chondrites, platy hibonite crystals in CM (Mighei-like) chondrites, and CAIs with fractionation and unidentified nuclear effects CAIs chondrites. Considering the apparently early and short duration (<0.3 Ma) of condensation of refractory {sup 16}O-rich solids in the SS, we infer that {sup 26}Al was injected into the collapsing protosolar molecular cloud and later homogenized in the protoplanetary disk. The apparent lack of correlation between {sup 26}Al abundance and O-isotope composition of corundum grains constrains the stellar source of {sup 26}Al in the SS.

  20. The development and testing of a 2D laboratory seismic modelling system for heterogeneous structure investigations

    NASA Astrophysics Data System (ADS)

    Mo, Yike; Greenhalgh, Stewart A.; Robertsson, Johan O. A.; Karaman, Hakki

    2015-05-01

    Lateral velocity variations and low velocity near-surface layers can produce strong scattered and guided waves which interfere with reflections and lead to severe imaging problems in seismic exploration. In order to investigate these specific problems by laboratory seismic modelling, a simple 2D ultrasonic model facility has been recently assembled within the Wave Propagation Lab at ETH Zurich. The simulated geological structures are constructed from 2 mm thick metal and plastic sheets, cut and bonded together. The experiments entail the use of a piezoelectric source driven by a pulse amplifier at ultrasonic frequencies to generate Lamb waves in the plate, which are detected by piezoelectric receivers and recorded digitally on a National Instruments recording system, under LabVIEW software control. The 2D models employed were constructed in-house in full recognition of the similitude relations. The first heterogeneous model features a flat uniform low velocity near-surface layer and deeper dipping and flat interfaces separating different materials. The second model is comparable but also incorporates two rectangular shaped inserts, one of low velocity, the other of high velocity. The third model is identical to the second other than it has an irregular low velocity surface layer of variable thickness. Reflection as well as transmission experiments (crosshole & vertical seismic profiling) were performed on each model. The two dominant Lamb waves recorded are the fundamental symmetric mode (non-dispersive) and the fundamental antisymmetric (flexural) dispersive mode, the latter normally being absent when the source transducer is located on a model edge but dominant when it is on the flat planar surface of the plate. Experimental group and phase velocity dispersion curves were determined and plotted for both modes in a uniform aluminium plate. For the reflection seismic data, various processing techniques were applied, as far as pre-stack Kirchhoff migration. The

  1. {alpha}- and {beta}-La{sub 4}Ti{sub 9}Si{sub 4}O{sub 30}. Synthesis and structure of the second member (m = 2) of novel layered oxosilicates containing (110) rutile sheets. Electrical property and band structure characterization of the mixed-valence titanium(III/IV) oxosilicate series, La{sub 4}Ti(Si{sub 2}O{sub 7}){sub 2}(TiO{sub 2}){sub 4m} (m = 1, 2)

    SciTech Connect

    Wang, S.; Hwu, S.J.; Paradis, J.A.; Whangbo, M.H.

    1995-05-24

    Detailed description is presented of molten salt synthesis, single crystal structures, and a comparison is offered of the {alpha}- and {beta}-La{sub 4}Ti{sub 9}Si{sub 4}O{sub 30} phases. The electrical property and band struture of this mixed-valence titanium (III/IV) oxosilicate series, La{sub 4}Ti(Si{sub 2}O{sub 7}){sub 2}(TiO{sub 2}){sub 4m} (m = 1,2), are discussed in terms of electronic interactions in a confined space with respect to the (110) rutile sheets. The results from the extended Hueckel tight binding calculations and the bond valence sum analysis are contrasted with regard to charge distribution. 33 refs., 9 figs., 3 tabs.

  2. μPIV methodology using model systems for flow studies in heterogeneous biopolymer gel microstructures.

    PubMed

    Sott, Kristin; Gebäck, Tobias; Pihl, Maria; Lorén, Niklas; Hermansson, Anne-Marie; Heintz, Alexei; Rasmuson, Anders

    2013-05-15

    A methodology for studying flow in heterogeneous soft microstructures has been developed. The methodology includes: (1) model fractal or random heterogeneous microstructures fabricated in PDMS and characterised using CLSM; (2) μPIV measurements; (3) Lattice-Boltzmann simulations of flow. It has been found that the flow behaviour in these model materials is highly dependent on pore size as well as on the connectivity and occurrence of dead ends. The experimental flow results show good agreement with predictions from the Lattice-Boltzmann modelling. These simulations were performed in geometries constructed from 3D CLSM images of the actual PDMS structures. Given these results, mass transport behaviour may be predicted for even more complex structures, like gels or composite material in, e.g., food or biomaterials. This is a step in the direction towards predictive science with regards to tailoring soft biomaterials for specific mass transport properties. PMID:23489610

  3. Plasmonic nanobubbles for target cell-specific gene and drug delivery and multifunctional processing of heterogeneous cell systems

    NASA Astrophysics Data System (ADS)

    Lukianova-Hleb, Ekaterina Y.; Huye, Leslie E.; Brenner, Malcolm K.; Lapotko, Dmitri O.

    2014-03-01

    Cell and gene cancer therapies require ex vivo cell processing of human grafts. Such processing requires at least three steps - cell enrichment, cell separation (destruction), and gene transfer - each of which requires the use of a separate technology. While these technologies may be satisfactory for research use, they are of limited usefulness in the clinical treatment setting because they have a low processing rate, as well as a low transfection and separation efficacy and specificity in heterogeneous human grafts. Most problematic, because current technologies are administered in multiple steps - rather than in a single, multifunctional, and simultaneous procedure - they lengthen treatment process and introduce an unnecessary level of complexity, labor, and resources into clinical treatment; all these limitations result in high losses of valuable cells. We report a universal, high-throughput, and multifunctional technology that simultaneously (1) inject free external cargo in target cells, (2) destroys unwanted cells, and (3) preserve valuable non-target cells in heterogeneous grafts. Each of these functions has single target cell specificity in heterogeneous cell system, processing rate > 45 mln cell/min, injection efficacy 90% under 96% viability of the injected cells, target cell destruction efficacy > 99%, viability of not-target cells >99% The developed technology employs novel cellular agents, called plasmonic nanobubbles (PNBs). PNBs are not particles, but transient, intracellular events, a vapor nanobubbles that expand and collapse in mere nanoseconds under optical excitation of gold nanoparticles with short picosecond laser pulses. PNBs of different, cell-specific, size (1) inject free external cargo with small PNBs, (2) Destroy other target cells mechanically with large PNBs and (3) Preserve non-target cells. The multi-functionality, precision, and high throughput of all-in-one PNB technology will tremendously impact cell and gene therapies and other

  4. Migration and Entrapment of DNAPLs in Heterogeneous Systems: Impact of Waste and Porous Medium Composition

    SciTech Connect

    Linda M. Abriola; Avery H. Demond

    2005-01-10

    Dense nonaqueous phase liquids (DNAPLs) pose a significant threat to soil and groundwater at Department of Energy (DOE) sites. Evidence suggests that subsurface wettability variations are present at many of these sites as a result of spatical and temporal variations in aqueous phase chemistry, contaminant aging, mineralogy and organic matter. The presence of such heterogeneity may significantly influence DNAPL migration and entrapment in the saturated zone.

  5. The impact of reservoir conditions and rock heterogeneity on multiphase flow in CO2-brine-sandstone systems

    NASA Astrophysics Data System (ADS)

    Krevor, S. C.; Reynolds, C. A.; Al-Menhali, A.; Niu, B.

    2015-12-01

    Capillary strength and multiphase flow are key for modeling CO2 injection for CO2 storage. Past observations of multiphase flow in this system have raised important questions about the impact of reservoir conditions on flow through effects on wettability, interfacial tension and fluid-fluid mass transfer. In this work we report the results of an investigation aimed at resolving many of these outstanding questions for flow in sandstone rocks. The drainage capillary pressure, drainage and imbibition relative permeability, and residual trapping [1] characteristic curves have been characterized in Bentheimer and Berea sandstone rocks across a pressure range 5 - 20 MPa, temperatures 25 - 90 C and brine salinities 0-5M NaCl. Over 30 reservoir condition core flood tests were performed using techniques including the steady state relative permeability test, the semi-dynamic capillary pressure test, and a new test for the construction of the residual trapping initial-residual curve. Test conditions were designed to isolate effects of interfacial tension, viscosity ratio, density ratio, and salinity. The results of the tests show that, in the absence of rock heterogeneity, reservoir conditions have little impact on flow properties, consistent with continuum scale multiphase flow theory for water wet systems. The invariance of the properties is observed, including transitions of the CO2 from a gas to a liquid to a supercritical fluid, and in comparison with N2-brine systems. Variations in capillary pressure curves are well explained by corresponding changes in IFT although some variation may reflect small changes in wetting properties. The low viscosity of CO2at certain conditions results in sensitivity to rock heterogeneity. We show that (1) heterogeneity is the likely source of uncertainty around past relative permeability observations and (2) that appropriate scaling of the flow potential by a quantification of capillary heterogeneity allows for the selection of core flood

  6. Extensions to the Parallel Real-Time Artificial Intelligence System (PRAIS) for fault-tolerant heterogeneous cycle-stealing reasoning

    NASA Technical Reports Server (NTRS)

    Goldstein, David

    1991-01-01

    Extensions to an architecture for real-time, distributed (parallel) knowledge-based systems called the Parallel Real-time Artificial Intelligence System (PRAIS) are discussed. PRAIS strives for transparently parallelizing production (rule-based) systems, even under real-time constraints. PRAIS accomplished these goals (presented at the first annual C Language Integrated Production System (CLIPS) conference) by incorporating a dynamic task scheduler, operating system extensions for fact handling, and message-passing among multiple copies of CLIPS executing on a virtual blackboard. This distributed knowledge-based system tool uses the portability of CLIPS and common message-passing protocols to operate over a heterogeneous network of processors. Results using the original PRAIS architecture over a network of Sun 3's, Sun 4's and VAX's are presented. Mechanisms using the producer-consumer model to extend the architecture for fault-tolerance and distributed truth maintenance initiation are also discussed.

  7. Modeling impacts of subscale heterogeneities on dispersive solute transport in subsurface systems.

    PubMed

    Vishal, Vikrant; Leung, Juliana Y

    2015-11-01

    Previous works in the literature demonstrated that dispersion increases with heterogeneities and travel distance in heterogeneous reservoirs. However, it remains challenging to quantify the effects of subscale heterogeneities on dispersion. Scale-up of input dispersivity and other reservoir attributes to the transport modeling scale should account for subscale heterogeneity and its variability. A method is proposed to quantify the uncertainties in reservoir attributes and dispersivity introduced by scale-up. A random walk particle tracking (RWPT) method, which is not prone to numerical dispersion, is used for transport modeling. First, to scale-up rock properties including porosity and permeability, volume variance at the transport modeling scale is computed corresponding to a given spatial correlation model; numerous sets of "conditioning data" are sampled from probability distributions whose mean is the block average of the actual measure values and the variance is the variance of block mean. Stochastic simulations are subsequently performed to generate multiple realizations at the transport modeling scale. Next, multiple sub-grid geostatistical realizations depicting detailed fine-scale heterogeneities and of the same physical sizes as the transport modeling grid block are subjected to RWPT simulation. Effective longitudinal and transverse (horizontal) dispersivities in two-dimensional models are determined simultaneously by matching the corresponding breakthrough concentration history for each realization with an equivalent medium consisting of averaged homogeneous rock properties. Aggregating results derived with all realizations, we generate probability distributions of scaled-up dispersivities conditional to particular averaged rock properties, from which values representative of the transport modeling scale are randomly drawn. The method is applied to model a tracer injection process. Results obtained from coarse-scale models, where reservoir properties and

  8. Bacterial Dispersal Promotes Biodegradation in Heterogeneous Systems Exposed to Osmotic Stress.

    PubMed

    Worrich, Anja; König, Sara; Banitz, Thomas; Centler, Florian; Frank, Karin; Thullner, Martin; Harms, Hauke; Miltner, Anja; Wick, Lukas Y; Kästner, Matthias

    2016-01-01

    Contaminant biodegradation in soils is hampered by the heterogeneous distribution of degrading communities colonizing isolated microenvironments as a result of the soil architecture. Over the last years, soil salinization was recognized as an additional problem especially in arid and semiarid ecosystems as it drastically reduces the activity and motility of bacteria. Here, we studied the importance of different spatial processes for benzoate biodegradation at an environmentally relevant range of osmotic potentials (ΔΨo) using model ecosystems exhibiting a heterogeneous distribution of the soil-borne bacterium Pseudomonas putida KT2440. Three systematically manipulated scenarios allowed us to cover the effects of (i) substrate diffusion, (ii) substrate diffusion and autonomous bacterial dispersal, and (iii) substrate diffusion and autonomous as well as mediated bacterial dispersal along glass fiber networks mimicking fungal hyphae. To quantify the relative importance of the different spatial processes, we compared these heterogeneous scenarios to a reference value obtained for each ΔΨo by means of a quasi-optimal scenario in which degraders were ab initio homogeneously distributed. Substrate diffusion as the sole spatial process was insufficient to counteract the disadvantage due to spatial degrader heterogeneity at ΔΨo ranging from 0 to -1 MPa. In this scenario, only 13.8-21.3% of the quasi-optimal biodegradation performance could be achieved. In the same range of ΔΨo values, substrate diffusion in combination with bacterial dispersal allowed between 68.6 and 36.2% of the performance showing a clear downwards trend with decreasing ΔΨo. At -1.5 MPa, however, this scenario performed worse than the diffusion scenario, possibly as a result of energetic disadvantages associated with flagellum synthesis and emerging requirements to exceed a critical population density to resist osmotic stress. Network-mediated bacterial dispersal kept biodegradation almost

  9. Bacterial Dispersal Promotes Biodegradation in Heterogeneous Systems Exposed to Osmotic Stress

    PubMed Central

    Worrich, Anja; König, Sara; Banitz, Thomas; Centler, Florian; Frank, Karin; Thullner, Martin; Harms, Hauke; Miltner, Anja; Wick, Lukas Y.; Kästner, Matthias

    2016-01-01

    Contaminant biodegradation in soils is hampered by the heterogeneous distribution of degrading communities colonizing isolated microenvironments as a result of the soil architecture. Over the last years, soil salinization was recognized as an additional problem especially in arid and semiarid ecosystems as it drastically reduces the activity and motility of bacteria. Here, we studied the importance of different spatial processes for benzoate biodegradation at an environmentally relevant range of osmotic potentials (ΔΨo) using model ecosystems exhibiting a heterogeneous distribution of the soil-borne bacterium Pseudomonas putida KT2440. Three systematically manipulated scenarios allowed us to cover the effects of (i) substrate diffusion, (ii) substrate diffusion and autonomous bacterial dispersal, and (iii) substrate diffusion and autonomous as well as mediated bacterial dispersal along glass fiber networks mimicking fungal hyphae. To quantify the relative importance of the different spatial processes, we compared these heterogeneous scenarios to a reference value obtained for each ΔΨo by means of a quasi-optimal scenario in which degraders were ab initio homogeneously distributed. Substrate diffusion as the sole spatial process was insufficient to counteract the disadvantage due to spatial degrader heterogeneity at ΔΨo ranging from 0 to −1 MPa. In this scenario, only 13.8−21.3% of the quasi-optimal biodegradation performance could be achieved. In the same range of ΔΨo values, substrate diffusion in combination with bacterial dispersal allowed between 68.6 and 36.2% of the performance showing a clear downwards trend with decreasing ΔΨo. At −1.5 MPa, however, this scenario performed worse than the diffusion scenario, possibly as a result of energetic disadvantages associated with flagellum synthesis and emerging requirements to exceed a critical population density to resist osmotic stress. Network-mediated bacterial dispersal kept biodegradation

  10. HIV heterogeneity and proximity of homestead to roads in rural South Africa: an exploration using a geographical information system.

    PubMed

    Tanser, F; Lesueur, D; Solarsh, G; Wilkinson, D

    2000-01-01

    objective To describe heterogeneity of HIV prevalence among pregnant women in Hlabisa health district, South Africa and to correlate this with proximity of homestead to roads. methods HIV prevalence measured through anonymous surveillance among pregnant women and stratified by local village clinic. Polygons were created around each clinic, assuming women attend the clinic nearest their home. A geographical information system (GIS) calculated the mean distance from homesteads in each clinic catchment to nearest primary (1 degrees ) and to nearest primary or secondary (2 degrees ) road. results We found marked HIV heterogeneity by clinic catchment (range 19-31% (P < 0.001). A polygon plot demonstrated lower HIV prevalence in catchments remote from 1 degrees roads. Mean distance from homesteads to nearest 1 degrees or 2 degrees road varied by clinic catchment from 1623 to 7569 m. The mean distance from homesteads to a 1 degrees or 2 degrees road for each clinic catchment was strongly correlated with HIV prevalence (r = 0.66; P = 0.002). conclusions The substantial HIV heterogeneity in this district is closely correlated with proximity to a 1 degrees or 2 degrees road. GIS is a powerful tool to demonstrate and to start to analyse this observation. Further research is needed to better understand this relationship both at ecological and individual levels, and to develop interventions to reduce the spread of HIV infection.

  11. A novel heterogeneous algorithm to simulate multiphase flow in porous media on multicore CPU-GPU systems

    NASA Astrophysics Data System (ADS)

    McClure, J. E.; Prins, J. F.; Miller, C. T.

    2014-07-01

    Multiphase flow implementations of the lattice Boltzmann method (LBM) are widely applied to the study of porous medium systems. In this work, we construct a new variant of the popular “color” LBM for two-phase flow in which a three-dimensional, 19-velocity (D3Q19) lattice is used to compute the momentum transport solution while a three-dimensional, seven velocity (D3Q7) lattice is used to compute the mass transport solution. Based on this formulation, we implement a novel heterogeneous GPU-accelerated algorithm in which the mass transport solution is computed by multiple shared memory CPU cores programmed using OpenMP while a concurrent solution of the momentum transport is performed using a GPU. The heterogeneous solution is demonstrated to provide speedup of 2.6× as compared to multi-core CPU solution and 1.8× compared to GPU solution due to concurrent utilization of both CPU and GPU bandwidths. Furthermore, we verify that the proposed formulation provides an accurate physical representation of multiphase flow processes and demonstrate that the approach can be applied to perform heterogeneous simulations of two-phase flow in porous media using a typical GPU-accelerated workstation.

  12. Bioinspired Hydrogenase Models: The Mixed-Valence Triiron Complex [Fe3(CO)7(μ-edt)2] and Phosphine Derivatives [Fe3(CO)7–x(PPh3)x(μ-edt)2] (x = 1, 2) and [Fe3(CO)5(κ2-diphosphine)(μ-edt)2] as Proton Reduction Catalysts

    PubMed Central

    2014-01-01

    The mixed-valence triiron complexes [Fe3(CO)7–x(PPh3)x(μ-edt)2] (x = 0–2; edt = SCH2CH2S) and [Fe3(CO)5(κ2-diphosphine)(μ-edt)2] (diphosphine = dppv, dppe, dppb, dppn) have been prepared and structurally characterized. All adopt an anti arrangement of the dithiolate bridges, and PPh3 substitution occurs at the apical positions of the outer iron atoms, while the diphosphine complexes exist only in the dibasal form in both the solid state and solution. The carbonyl on the central iron atom is semibridging, and this leads to a rotated structure between the bridged diiron center. IR studies reveal that all complexes are inert to protonation by HBF4·Et2O, but addition of acid to the pentacarbonyl complexes results in one-electron oxidation to yield the moderately stable cations [Fe3(CO)5(PPh3)2(μ-edt)2]+ and [Fe3(CO)5(κ2-diphosphine)(μ-edt)2]+, species which also result upon oxidation by [Cp2Fe][PF6]. The electrochemistry of the formally Fe(I)–Fe(II)–Fe(I) complexes has been investigated. Each undergoes a quasi-reversible oxidation, the potential of which is sensitive to phosphine substitution, generally occurring between 0.15 and 0.50 V, although [Fe3(CO)5(PPh3)2(μ-edt)2] is oxidized at −0.05 V. Reduction of all complexes is irreversible and is again sensitive to phosphine substitution, varying between −1.47 V for [Fe3(CO)7(μ-edt)2] and around −1.7 V for phosphine-substituted complexes. In their one-electron-reduced states, all complexes are catalysts for the reduction of protons to hydrogen, the catalytic overpotential being increased upon successive phosphine substitution. In comparison to the diiron complex [Fe2(CO)6(μ-edt)], [Fe3(CO)7(μ-edt)2] catalyzes proton reduction at 0.36 V less negative potentials. Electronic structure calculations have been carried out in order to fully elucidate the nature of the oxidation and reduction processes. In all complexes, the HOMO comprises an iron–iron bonding orbital localized between the two iron

  13. (NH{sub 4})[V{sub 1-x}{sup III}V{sub x}{sup IV}(AsO{sub 4})F{sub 1-x}O{sub x}]: A new mixed valence vanadium(III,IV) fluoro-arsenate with ferromagnetic interactions and electronic conductivity

    SciTech Connect

    Berrocal, Teresa

    2009-01-15

    A new mixed valence vanadium(III,IV) fluoro-arsenate compound, with formula (NH{sub 4})[V{sub 1-x}{sup III}V{sub x}{sup IV}(AsO{sub 4})F{sub 1-x}O{sub x}] and KTP structure-type, has been synthesized by mild hydrothermal techniques. The crystal structure has been solved from single crystal X-ray diffraction data in the Pna2{sub 1} orthorhombic space group. The unit-cell parameters are a=13.196(2) A, b=6.628(1) A and c=10.7379(7) A with Z=8. The final R factors were R1=0.0438 and wR2=0.0943 [all data]. The crystal structure consists of a three-dimensional framework formed by (V{sup III,IV}O{sub 4}F{sub 2}) octahedra and (AsO{sub 4}){sup 3-} tetrahedra arsenate oxoanions. The vanadium(III,IV) cations, from the (V{sup III,IV}O{sub 4}F{sub 2}) octahedra, are linked through the fluorine atoms giving rise to zigzag chains. The ammonium cations are located in the cavities of the structure compensating the anionic charge of the [V{sub 1-x}{sup III}V{sub x}{sup IV}(AsO{sub 4})F{sub 1-x}O{sub x}]{sup -} inorganic skeleton. The thermal stability limit of the phase is 345 deg. C, around to this temperature the ammonium cation and fluoride anion are lost. The IR spectrum shows the characteristic bands of the (NH{sub 4}){sup +} and (AsO{sub 4}){sup 3-} ions. Magnetic measurements indicate the existence of weak ferromagnetic interactions. Electronic conductivity, via a hopping mechanism, occurs with an activation energy of 0.66 eV. - Graphical abstract: Polyhedral view of the crystal structure of (NH{sub 4})[V{sup III}{sub 1-x}V{sup IV}{sub x}(AsO{sub 4})F{sub 1-x}O{sub x}].

  14. Aggregation in environmental systems: seasonal tracer cycles quantify young water fractions, but not mean transit times, in spatially heterogeneous catchments

    NASA Astrophysics Data System (ADS)

    Kirchner, J. W.

    2015-03-01

    Environmental heterogeneity is ubiquitous, but environmental systems are often analyzed as if they were homogeneous instead, resulting in aggregation errors that are rarely explored and almost never quantified. Here I use simple benchmark tests to explore this general problem in one specific context: the use of seasonal cycles in chemical or isotopic tracers (such as Cl-, δ18O, or δ2H) to estimate timescales of storage in catchments. Timescales of catchment storage are typically quantified by the mean transit time, meaning the average time that elapses between parcels of water entering as precipitation and leaving again as streamflow. Longer mean transit times imply greater damping of seasonal tracer cycles. Thus, the amplitudes of tracer cycles in precipitation and streamflow are commonly used to calculate catchment mean transit times. Here I show that these calculations will typically be wrong by several hundred percent, when applied to catchments with realistic degrees of spatial heterogeneity. This aggregation bias arises from the strong nonlinearity in the relationship between tracer cycle amplitude and mean travel time. I propose an alternative storage metric, the young water fraction in streamflow, defined as the fraction of runoff with transit times of less than roughly 0.2 years. I show that this young water fraction (not to be confused with event-based "new water" in hydrograph separations) is accurately predicted by seasonal tracer cycles within a precision of a few percent, across the entire range of mean transit times from almost zero to almost infinity. Importantly, this relationship is also virtually free from aggregation error. That is, seasonal tracer cycles also accurately predict the young water fraction in runoff from highly heterogeneous mixtures of subcatchments with strongly contrasting transit time distributions. Thus, although tracer cycle amplitudes yield biased and unreliable estimates of catchment mean travel times in heterogeneous

  15. Homogeneous and Heterogeneous Reaction and Transformation of Hg and Trace Metals in Combustion Systems

    SciTech Connect

    J. Helble; Clara Smith; David Miller

    2009-08-31

    The overall goal of this project was to produce a working dynamic model to predict the transformation and partitioning of trace metals resulting from combustion of a broad range of fuels. The information provided from this model will be instrumental in efforts to identify fuels and conditions that can be varied to reduce metal emissions. Through the course of this project, it was determined that mercury (Hg) and arsenic (As) would be the focus of the experimental investigation. Experiments were therefore conducted to examine homogeneous and heterogeneous mercury oxidation pathways, and to assess potential interactions between arsenic and calcium. As described in this report, results indicated that the role of SO{sub 2} on Hg oxidation was complex and depended upon overall gas phase chemistry, that iron oxide (hematite) particles contributed directly to heterogeneous Hg oxidation, and that As-Ca interactions occurred through both gas-solid and within-char reaction pathways. Modeling based on this study indicated that, depending upon coal type and fly ash particle size, vaporization-condensation, vaporization-surface reaction, and As-CaO in-char reaction all play a role in arsenic transformations under combustion conditions.

  16. Heterogeneous Catalysis.

    ERIC Educational Resources Information Center

    Miranda, R.

    1989-01-01

    Described is a heterogeneous catalysis course which has elements of materials processing embedded in the classical format of catalytic mechanisms and surface chemistry. A course outline and list of examples of recent review papers written by students are provided. (MVL)

  17. Integration of heterogeneous clinical decision support systems and their knowledge sets: feasibility study with Drug-Drug Interaction alerts.

    PubMed

    Kam, Hye Jin; Kim, Jeong Ah; Cho, InSook; Kim, Yoon; Park, Rae Woong

    2011-01-01

    There exist limitations in both commercial and in-house clinical decision support systems (CDSSs) and issues related to the integration of different knowledge sources and CDSSs. We chose Standard-based Shareable Active Guideline Environment (SAGE) as a new architecture with knowledge integration and a centralized knowledge base which includes authoring/management functions and independent CDSS, and applied it to Drug-Drug Interaction (DDI) CDSS. The aim of this study was to evaluate the feasibility of the newly integrated DDI alerting CDSS into a real world hospital information system involving construction of an integrated CDSS derived from two heterogeneous systems and their knowledge sets. The proposed CDSS was successfully implemented and compensated for the weaknesses of the old CDSS from knowledge integration and management, and its applicability in actual situations was verified. Although the DDI CDSS was constructed as an example case, the new CDS architecture might prove applicable to areas of CDSSs.

  18. ISP: an optimal out-of-core image-set processing streaming architecture for parallel heterogeneous systems.

    PubMed

    Ha, Linh Khanh; Krüger, Jens; Dihl Comba, João Luiz; Silva, Cláudio T; Joshi, Sarang

    2012-06-01

    Image population analysis is the class of statistical methods that plays a central role in understanding the development, evolution, and disease of a population. However, these techniques often require excessive computational power and memory that are compounded with a large number of volumetric inputs. Restricted access to supercomputing power limits its influence in general research and practical applications. In this paper we introduce ISP, an Image-Set Processing streaming framework that harnesses the processing power of commodity heterogeneous CPU/GPU systems and attempts to solve this computational problem. In ISP, we introduce specially designed streaming algorithms and data structures that provide an optimal solution for out-of-core multiimage processing problems both in terms of memory usage and computational efficiency. ISP makes use of the asynchronous execution mechanism supported by parallel heterogeneous systems to efficiently hide the inherent latency of the processing pipeline of out-of-core approaches. Consequently, with computationally intensive problems, the ISP out-of-core solution can achieve the same performance as the in-core solution. We demonstrate the efficiency of the ISP framework on synthetic and real datasets. PMID:22291156

  19. ISP: an optimal out-of-core image-set processing streaming architecture for parallel heterogeneous systems.

    PubMed

    Ha, Linh Khanh; Krüger, Jens; Dihl Comba, João Luiz; Silva, Cláudio T; Joshi, Sarang

    2012-06-01

    Image population analysis is the class of statistical methods that plays a central role in understanding the development, evolution, and disease of a population. However, these techniques often require excessive computational power and memory that are compounded with a large number of volumetric inputs. Restricted access to supercomputing power limits its influence in general research and practical applications. In this paper we introduce ISP, an Image-Set Processing streaming framework that harnesses the processing power of commodity heterogeneous CPU/GPU systems and attempts to solve this computational problem. In ISP, we introduce specially designed streaming algorithms and data structures that provide an optimal solution for out-of-core multiimage processing problems both in terms of memory usage and computational efficiency. ISP makes use of the asynchronous execution mechanism supported by parallel heterogeneous systems to efficiently hide the inherent latency of the processing pipeline of out-of-core approaches. Consequently, with computationally intensive problems, the ISP out-of-core solution can achieve the same performance as the in-core solution. We demonstrate the efficiency of the ISP framework on synthetic and real datasets.

  20. An Analysis Framework for Investigating the Trade-offs Between System Performance and Energy Consumption in a Heterogeneous Computing Environment

    SciTech Connect

    Friese, Ryan; Khemka, Bhavesh; Maciejewski, Anthony A; Siegel, Howard Jay; Koenig, Gregory A; Powers, Sarah S; Hilton, Marcia M; Rambharos, Rajendra; Okonski, Gene D; Poole, Stephen W

    2013-01-01

    Rising costs of energy consumption and an ongoing effort for increases in computing performance are leading to a significant need for energy-efficient computing. Before systems such as supercomputers, servers, and datacenters can begin operating in an energy-efficient manner, the energy consumption and performance characteristics of the system must be analyzed. In this paper, we provide an analysis framework that will allow a system administrator to investigate the tradeoffs between system energy consumption and utility earned by a system (as a measure of system performance). We model these trade-offs as a bi-objective resource allocation problem. We use a popular multi-objective genetic algorithm to construct Pareto fronts to illustrate how different resource allocations can cause a system to consume significantly different amounts of energy and earn different amounts of utility. We demonstrate our analysis framework using real data collected from online benchmarks, and further provide a method to create larger data sets that exhibit similar heterogeneity characteristics to real data sets. This analysis framework can provide system administrators with insight to make intelligent scheduling decisions based on the energy and utility needs of their systems.

  1. Establishing a geochemical heterogeneity model for a contaminated vadose zone--aquifer system.

    PubMed

    Murray, Christopher J; Zachara, John M; McKinley, James P; Ward, Andy; Bott, Yi-Ju; Draper, Kate; Moore, Dean

    2013-10-01

    A large set of sediment samples from a 1600 m² experimental plot within a 2.2 km² vadose zone and groundwater uranium (VI) plume was subject to physical, chemical, and mineralogic characterization. The plot is being used for field experimentation on U(VI) recharge and transport processes within a persistent groundwater plume that exists in the groundwater-river interaction zone of the Columbia River at the U.S. DOE Hanford site. The samples were obtained during the installation of 35 tightly spaced (10 m separation) groundwater monitoring wells. The characterization measurements for each sample included total contaminant concentrations (U and Cu primarily), bicarbonate extractable U(VI), sequential ²³⁸U(VI) contaminant desorption Kd, ²³³U(VI) adsorption K(d), grain size distribution, surface area, extractable poorly crystalline Fe(III) oxides, and mineralogy. The characterization objective was to inform a conceptual model of coupled processes controlling the anomalous longevity of the plume, and to quantify the spatial heterogeneity of the contaminant inventory and the primary properties effecting reactive transport. Correlations were drawn between chemical, physical, and reaction properties, and Gaussian simulation was used to compute multiple 3-D realizations of extractable U(VI), the ²³³U(VI) adsorption K(d), and the distribution of the reactive <2 mm fraction. Adsorbed contaminant U(VI) was highest in the vadose zone and the zone of seasonal water table fluctuation lying at its base. Adsorbed U(VI) was measureable, but low, in the groundwater plume region where very high hydraulic conductivities existed. The distribution of adsorbed U(VI) displayed no apparent correlation with sediment physical or chemical properties. Desorption [²³⁸U(IV)] and adsorption [²³³U(VI)] K(d) values showed appreciable differences due to mass transfer controlled surface complexation and the effects of long subsurface residence times. The ²³³U(VI) adsorption K

  2. Benchmarking of hospital information systems: Monitoring of discharge letters and scheduling can reveal heterogeneities and time trends

    PubMed Central

    Dugas, Martin; Eckholt, Markus; Bunzemeier, Holger

    2008-01-01

    Background Monitoring of hospital information system (HIS) usage can provide insights into best practices within a hospital and help to assess time trends. In terms of effort and cost of benchmarking, figures derived automatically from the routine HIS system are preferable to manual methods like surveys, in particular for repeated analysis. Methods Due to relevance for quality management and efficient resource utilization we focused on time-to-completion of discharge letters (assessed by CT-plots) and usage of patient scheduling. We analyzed these parameters monthly during one year at a major university hospital in Germany. Results We found several distinct patterns of discharge letter documentation indicating a large heterogeneity of HIS usage between different specialties (completeness 51 – 99%, delays 0 – 90 days). Overall usage of scheduling increased during the observation period by 62%, but again showed a considerable variation between departments. Conclusion Regular monitoring of HIS key figures can contribute to a continuous HIS improvement process. PMID:18423046

  3. Use of Persistent Identifiers to link Heterogeneous Data Systems in the Integrated Earth Data Applications (IEDA) Facility

    NASA Astrophysics Data System (ADS)

    Hsu, L.; Lehnert, K. A.; Carbotte, S. M.; Arko, R. A.; Ferrini, V.; O'hara, S. H.; Walker, J. D.

    2012-12-01

    The Integrated Earth Data Applications (IEDA) facility maintains multiple data systems with a wide range of solid earth data types from the marine, terrestrial, and polar environments. Examples of the different data types include syntheses of ultra-high resolution seafloor bathymetry collected on large collaborative cruises and analytical geochemistry measurements collected by single investigators in small, unique projects. These different data types have historically been channeled into separate, discipline-specific databases with search and retrieval tailored for the specific data type. However, a current major goal is to integrate data from different systems to allow interdisciplinary data discovery and scientific analysis. To increase discovery and access across these heterogeneous systems, IEDA employs several unique IDs, including sample IDs (International Geo Sample Number, IGSN), person IDs (GeoPass ID), funding award IDs (NSF Award Number), cruise IDs (from the Marine Geoscience Data System Expedition Metadata Catalog), dataset IDs (DOIs), and publication IDs (DOIs). These IDs allow linking of a sample registry (System for Earth SAmple Registration), data libraries and repositories (e.g. Geochemical Research Library, Marine Geoscience Data System), integrated synthesis databases (e.g. EarthChem Portal, PetDB), and investigator services (IEDA Data Compliance Tool). The linked systems allow efficient discovery of related data across different levels of granularity. In addition, IEDA data systems maintain links with several external data systems, including digital journal publishers. Links have been established between the EarthChem Portal and ScienceDirect through publication DOIs, returning sample-level objects and geochemical analyses for a particular publication. Linking IEDA-hosted data to digital publications with IGSNs at the sample level and with IEDA-allocated dataset DOIs are under development. As an example, an individual investigator could sign up

  4. SU-E-T-162: Evaluation of Dose Calculation of RayStation Planning System in Heterogeneous Media

    SciTech Connect

    Xu, H; Yi, B; Chung, H; Prado, K; Chen, S

    2014-06-01

    Purpose: To investigate the clinical reliability of heterogeneity-based dose algorithm using RayStation treatment planning system v.4.0. Methods: The collapsed cone dose calculations in RayStation (RaySearch, Sweden) were compared with the measurements (ion chamber and EBT2 film) and with an in-house Monte Carlo algorithm. A heterogeneous multi-layer phantom and CT images of 4 lung cancer patients were used here. The phantom, composed of multiple solid water slabs and Styrofoams, was irradiated with 6MV beams perpendicular to the layers. The MLC-defined field sizes were 5×5, 10×10, 15×15 and 20×20cm{sup 2}. The chamber was positioned at center of central solid water layer, and the films were placed at interfaces of solid water and Styrofoam. The RayStation dose and Monte Carlo dose were compared by performing absolute gamma analysis (3mm/3%): 1D gamma for PDD in the phantom and 3D gamma for patient volumes receiving dose above 10% of maximum dose. Results: The point dose differences between RayStation and ion chamber measurement were smaller than 1% for all of the field sizes. Between RayStation and film measurement, 5×5cm2 field had the maximum differences : <4mm for the penumbra and <0.3mm for the field width at all Styrofoam-and-solid-water interfaces. The absolute gamma analysis showed good agreement between RayStation and Monte Carlo. For PDD along beam axis in the phantom, the 1D gamma was 95.4, 98.6, 99.6 and 99.3% for field size 5×5, 10×10, 15×15 and 20×202 respectively. For dose comparison using patient CT images, 3D gamma was > 95% for all the patients. Conclusion: With respect to ion chamber/film measurement and Monte Carlo calculation, the collapsed cone algorithm in RayStation computed reasonable dose in both phantom and patient cases. Heterogeneity-based dose calculation of RayStation is clinically acceptable in heterogeneous media.

  5. Performance of Goddard Earth Observing System GCM Column Radiation Models under Heterogeneous Cloud Conditions

    NASA Technical Reports Server (NTRS)

    Oreopoulos, L.; Chou, M.-D.; Khairoutdinov, M.; Barker, H. W.; Cahalan, R. F.

    2003-01-01

    We test the performance of the shortwave (SW) and longwave (LW) Column Radiation Models (CORAMs) of Chou and collaborators with heterogeneous cloud fields from a global single-day dataset produced by NCAR's Community Atmospheric Model with a 2-D CRM installed in each gridbox. The original SW version of the CORAM performs quite well compared to reference Independent Column Approximation (ICA) calculations for boundary fluxes, largely due to the success of a combined overlap and cloud scaling parameterization scheme. The absolute magnitude of errors relative to ICA are even smaller for the LW CORAM which applies similar overlap. The vertical distribution of heating and cooling within the atmosphere is also simulated quite well with daily-averaged zonal errors always below 0.3 K/d for SW heating rates and 0.6 K/d for LW cooling rates. The SW CORAM's performance improves by introducing a scheme that accounts for cloud inhomogeneity. These results suggest that previous studies demonstrating the inaccuracy of plane-parallel models may have unfairly focused on worst scenario cases, and that current radiative transfer algorithms of General Circulation Models (GCMs) may be more capable than previously thought in estimating realistic spatial and temporal averages of radiative fluxes, as long as they are provided with correct mean cloud profiles. However, even if the errors of the particular CORAMs are small, they seem to be systematic, and the impact of the biases can be fully assessed only with GCM climate simulations.

  6. Non local Lotka-Volterra system with cross-diffusion in an heterogeneous medium.

    PubMed

    Fontbona, Joaquin; Méléard, Sylvie

    2015-03-01

    We introduce a stochastic individual model for the spatial behavior of an animal population of dispersive and competitive species, considering various kinds of biological effects, such as heterogeneity of environmental conditions, mutual attractive or repulsive interactions between individuals or competition between them for resources. As a consequence of the study of the large population limit, global existence of a nonnegative weak solution to a multidimensional parabolic strongly coupled model of competing species is proved. The main new feature of the corresponding integro-differential equation is the nonlocal nonlinearity appearing in the diffusion terms, which may depend on the spatial densities of all population types. Moreover, the diffusion matrix is generally not strictly positive definite and the cross-diffusion effect allows for influences growing linearly with the subpopulations' sizes. We prove uniqueness of the finite measure-valued solution and give conditions under which the solution takes values in a functional space. We then make the competition kernels converge to a Dirac measure and obtain the existence of a solution to a locally competitive version of the previous equation. The techniques are essentially based on the underlying stochastic flow related to the dispersive part of the dynamics, and the use of suitable dual distances in the space of finite measures.

  7. Heterogeneous clusters as a model system for the study of ionization dynamics within tampered samples

    SciTech Connect

    Ziaja, B.; Chapman, H. N.; Santra, R.; Laarmann, T.; Weckert, E.; Bostedt, C.; Moeller, T.

    2011-09-15

    Tampering of a sample with a layer of another material is a promising technique to slow down the expansion dynamics within laser irradiated samples, with sound implications for single-particle diffraction imaging. Ideally, if an imaged object is covered by a layer of another material, during the irradiation this layer will be primarily ionized and will expand fast due to Coulomb repulsion, whereas the object located within the net neutral core will expand more slowly (hydrodynamically). We investigate the details of the electronic damage within the tampered samples during their irradiation with an intense extreme ultraviolet (EUV) pulse. We study heterogeneous clusters composed of noble gas atoms, Xe and Ar, for which chemical-bond effects can be neglected. Using a fully nonequilibrium kinetic equation code, we demonstrate the influence of cluster composition on ionization dynamics; in particular, on the electronic damage. The results are obtained for the wavelength of 32 nm, which is available at the free-electron laser in Hamburg (FLASH) facility, but our conclusions can also have implications for samples with a more complex structure and irradiated at a much shorter wavelength.

  8. Non local Lotka-Volterra system with cross-diffusion in an heterogeneous medium.

    PubMed

    Fontbona, Joaquin; Méléard, Sylvie

    2015-03-01

    We introduce a stochastic individual model for the spatial behavior of an animal population of dispersive and competitive species, considering various kinds of biological effects, such as heterogeneity of environmental conditions, mutual attractive or repulsive interactions between individuals or competition between them for resources. As a consequence of the study of the large population limit, global existence of a nonnegative weak solution to a multidimensional parabolic strongly coupled model of competing species is proved. The main new feature of the corresponding integro-differential equation is the nonlocal nonlinearity appearing in the diffusion terms, which may depend on the spatial densities of all population types. Moreover, the diffusion matrix is generally not strictly positive definite and the cross-diffusion effect allows for influences growing linearly with the subpopulations' sizes. We prove uniqueness of the finite measure-valued solution and give conditions under which the solution takes values in a functional space. We then make the competition kernels converge to a Dirac measure and obtain the existence of a solution to a locally competitive version of the previous equation. The techniques are essentially based on the underlying stochastic flow related to the dispersive part of the dynamics, and the use of suitable dual distances in the space of finite measures. PMID:24710661

  9. A new approach to network heterogeneity: Polymerization Induced Phase Separation in photo-initiated, free-radical methacrylic systems.

    PubMed

    Szczepanski, Caroline R; Pfeifer, Carmem S; Stansbury, Jeffrey W

    2012-09-28

    Non-reactive, thermoplastic prepolymers (poly- methyl, ethyl and butyl methacrylate) were added to a model homopolymer matrix composed of triethylene glycol dimethacrylate (TEGDMA) to form heterogeneous networks via polymerization induced phase separation (PIPS). PIPS creates networks with distinct phase structure that can partially compensate for volumetric shrinkage during polymerization through localized internal volume expansion. This investigation utilizes purely photo-initiated, free-radical systems, broadening the scope of applications for PIPS since these processing conditions have not been studied previously.The introduction of prepolymer into TEGDMA monomer resulted in stable, homogeneous monomer formulations, most of which underwent PIPS upon photo-irradiation, creating heterogeneous networks. During polymerization the presence of prepolymer enhanced autoacceleration, allowing for a more extensive ambient cure of the material. Phase separation, as characterized by dynamic changes in sample turbidity, was monitored simultaneously with monomer conversion and either preceded or was coincident with network gelation. Dynamic mechanical analysis shows a broadening of the tan delta peak and secondary peak formation, characteristic of phase-separated materials, indicating one phase rich in prepolymer and another depleted form upon phase separation. In certain cases, PIPS leads to an enhanced physical reduction of volumetric shrinkage, which is attractive for many applications including dental composite materials. PMID:23109733

  10. A software design approach for heterogeneous systems of unattended sensors, unmanned vehicles, and monitoring stations

    NASA Astrophysics Data System (ADS)

    Smuda, William J.; Gerhart, Grant; Shing, Man-Tak; Auguston, Mikhail

    2006-09-01

    The design and implementation of software for network systems of diverse physical assets is a continuing challenge to sensor network developers. The problems are often multiplied when adding new elements, and when reconfiguring existing systems. For software systems, like physical systems, explicit architectural descriptions increase system level comprehension. Coupled with well defined object oriented design practices, system extensibility is defined and software reuse and code composition are enabled. Our research is based on model driven design architecture. High level system models are defined in the Unified Modeling Language (UML), the language of the software engineer. However, since most experimental work is done by non-software specialists, (electronics Engineers, Mechanical Engineers and technicians) the model is translated into a graphical, domain specific model. Components are presented as domain specific icons, and constraints from the UML model are propagated into the domain model. Domain specialists manipulate the domain model, which then composes software elements needed at each node to create an aggregate system.

  11. Nonstationarity of the electrical resistivity and soil moisture relationship in a heterogeneous soil system: a case study

    NASA Astrophysics Data System (ADS)

    Michot, Didier; Thomas, Zahra; Adam, Issifou

    2016-06-01

    Understanding the role of vegetation in the interface between the atmosphere and groundwater is the most decisive key in analyzing the processes involved in water transfer. The main effect of vegetation is its root water uptake, which significantly modifies the processes involved in water transfer in the vadose zone. This paper focuses on mapping temporal and spatial changes in soil moisture using electrical resistivity tomography (ERT). The main objective is to assess how electrical resistivity (ER) is useful for mapping water distribution along a heterogeneous toposequence crossed by a hedgerow. Ten ERT were performed over the studied period for a 28 m long toposequence and compared to matric potential and groundwater level measurements. Soil volumetric water content (VWC) was predicted with two methods: (i) from ER using the Waxman and Smits model (ii) and from matric potential using an experimental retention curve fitted by a Van Genuchten model. Probability density functions (PDFs) of our set of data show that the largest change in mean ER and matric potential was observed in the topsoil layer. We then analyzed the consistency between ER and point measurements in this layer by extracting the arrays at the junction of ER grids and point measurements. PDFs of ER maps at each monitoring time (from T01 to T10) were also calculated to select the most contrasting distributions, corresponding to the wettest (T06) and driest states (T10). Results of ER were consistent with matric-potential measurements, with two different behaviors for locations inside and outside the root zone. A consistent correlation between VWC values from the Waxman and Smits model and those obtained from the retention curve was observed outside the root zone. The heterogeneous soil system inside the root zone shows a different pattern in this relationship. A shift in the relationship between ER and soil moisture for the locations outside and inside the root zone highlights the nonstationarity

  12. Non-stationarity of electrical resistivity and soil moisture relationship in heterogeneous soil system: a case study

    NASA Astrophysics Data System (ADS)

    Michot, D.; Thomas, Z.; Adam, I.

    2015-09-01

    Root uptake is the most decisive key in water transfer involving soil and vegetation. It depends on water availability which can be evaluated by punctual measurements. Additionally, surface geophysical methods such as Electrical Resistivity Tomography (ERT) provide larger spatial scales. This paper focuses on investigating temporal and spatial soil moisture changes, along a toposequence crossed by a hedgerow, using ERT and punctual measurements. 10 ERT were performed over the studied period for a 28 m long transect and compared to matric potential and groundwater level measurements. Soil Volumetric Water Content (VWC) was predicted using two methods (i) from ER using Waxman and Smits model (ii) and from matric potential using experimental retention curve fitted by Van Genuchten model. Probability Density Functions (Pdfs) of our set of data show that the largest change, in mean values of ER as well as matric potential, was observed in the topsoil layer. We then analyzed the consistency between ER and punctual measurements in this layer by extracting the arrays in the junction between ER grids and punctual measurements. Pdfs of ER maps at each monitoring time (from T01 to T10) were also calculated to select the more contrasted distributions corresponding to the wettest (T06) and driest states (T10). Results of ER were consistent with matric potential measurements with two different behaviors for locations inside and outside the root zone. A strong correlation (r = 0.9) between VWC values from Waxman and Smits model and those obtained from retention curve was observed outside the root zone. The heterogeneous soil system inside the root zone shows a different pattern in this relationship. The shift in the relationship between ER and soil moisture for the locations outside and inside the root zone highlights the non-stationarity in heterogeneous soil system. Such systems were actually related to the high hedgerow root density and also to a particular topographical

  13. Performance of Goddard earth observing system GCM column radiation models under heterogeneous cloud conditions

    NASA Astrophysics Data System (ADS)

    Oreopoulos, L.; Chou, M.-D.; Khairoutdinov, M.; Barker, H. W.; Cahalan, R. F.

    2004-11-01

    We test the performance of the shortwave (SW) and longwave (LW) Column Radiation Models (CORAMs) of Chou and collaborators with heterogeneous cloud fields from a single-day global dataset produced by NCAR's Community Atmospheric Model (CAM) with a 2-D Cloud Resolving Model (CRM) installed in each column. The original SW version of the CORAM performs quite well compared to reference Independent Column Approximation (ICA) calculations for boundary fluxes (global error ˜4 W m -2 for reflected flux), largely due to the success of a combined overlap and cloud scaling parameterization scheme. The absolute magnitude of errors relative to ICA are even smaller (global error ˜2 W m -2 for outgoing flux) for the LW CORAM which applies similar overlap. The vertical distribution of heating and cooling within the atmosphere is also simulated quite well with daily averaged zonal errors always less than 0.3 K/day for SW and 0.6 K/day for LW heating (cooling) rates. The SW CORAM's performance improves by introducing a scheme that accounts for cloud inhomogeneity based on the Gamma Weighted Two Stream Approximation (GWTSA). These results suggest that previous studies demonstrating the inaccuracy of plane-parallel models may have unfairly focused on worst case scenarios, and that current radiative transfer algorithms in General Circulation Models (GCMs) may be more capable than previously thought in estimating realistic spatial and temporal averages of radiative fluxes, as long as they are provided with correct mean cloud profiles. However, even if the errors of our particular CORAMs are small, they seem to be systematic, and their impact can be fully assessed only with GCM climate simulations.

  14. Nanoscale zero-valent iron incorporated with nanomagnetic diatomite for catalytic degradation of methylene blue in heterogeneous Fenton system.

    PubMed

    Zha, Yiming; Zhou, Ziqing; He, Haibo; Wang, Tianlin; Luo, Liqiang

    2016-01-01

    Nanoscale zero-valent iron (nZVI) incorporated with nanomagnetic diatomite (DE) composite material was prepared for catalytic degradation of methylene blue (MB) in heterogeneous Fenton system. The material was constructed by two facile steps: Fe3O4 magnetic nanoparticles were supported on DE by chemical co-precipitation method, after which nZVI was incorporated into magnetic DE by liquid-phase chemical reduction strategy. The as-prepared catalyst was characterized by scanning electron microscopy, Fourier-transform infrared spectroscopy, X-ray diffraction, magnetic properties measurement and nitrogen adsorption-desorption isotherm measurement. The novel nZVI@Fe3O4-diatomite nanocomposites showed a distinct catalytic activity and a desirable effect for degradation of MB. MB could be completely decolorized within 8 min and the removal efficiency of total organic carbon could reach to 90% after reaction for 1 h. PMID:27232419

  15. Effects of Microbial Colonization, Liquid Flow and Textural Heterogeneities on Gas-Phase Transport in Unsaturated Systems

    NASA Astrophysics Data System (ADS)

    Parker, L. B.; Yarwood, R. R.; Kraft, E. L.; Selker, J. S.

    2003-12-01

    Gaseous flow dynamics in unsaturated media were examined with respect to microbial colonization, liquid flow rates, and textural heterogeneities. A light transmission chamber consisting of two glass sheets mounted in an aluminum frame in front of a light bank was packed with translucent quartz sand and brought to unsaturated conditions. To visualize gas transport, carbon dioxide was introduced to the chamber at varying rates in combination with different liquid flow rates and textural inclusions. A methyl red pH indicator solution was used in conjunction with a liquid-cooled camera to monitor carbon dioxide concentrations and infer transport dynamics throughout the system. To explore whether gas-phase nutrients would stimulate microbial growth, acetate and ammonia vapors were pumped through a chamber inoculated with Pseudomonas fluorescens HK44. Naphthalene vapor pulses were used to induce bioluminescence, allowing imaging of responsive colonies.

  16. Multilevel Methodology for Simulation of Spatio-Temporal Systems with Heterogeneous Activity; Application to Spread of Valley Fever Fungus

    USGS Publications Warehouse

    Jammalamadaka, Rajanikanth

    2009-01-01

    This report consists of a dissertation submitted to the faculty of the Department of Electrical and Computer Engineering, in partial fulfillment of the requirements for the degree of Doctor of Philosophy, Graduate College, The University of Arizona, 2008. Spatio-temporal systems with heterogeneity in their structure and behavior have two major problems associated with them. The first one is that such complex real world systems extend over very large spatial and temporal domains and consume so many computational resources to simulate that they are infeasible to study with current computational platforms. The second one is that the data available for understanding such systems is limited because they are spread over space and time making it hard to obtain micro and macro measurements. This also makes it difficult to get the data for validation of their constituent processes while simultaneously considering their global behavior. For example, the valley fever fungus considered in this dissertation is spread over a large spatial grid in the arid Southwest and typically needs to be simulated over several decades of time to obtain useful information. It is also hard to get the temperature and moisture data (which are two critical factors on which the survival of the valley fever fungus depends) at every grid point of the spatial domain over the region of study. In order to address the first problem, we develop a method based on the discrete event system specification which exploits the heterogeneity in the activity of the spatio-temporal system and which has been shown to be effective in solving relatively simple partial differential equation systems. The benefit of addressing the first problem is that it now makes it feasible to address the second problem. We address the second problem by making use of a multilevel methodology based on modeling and simulation and systems theory. This methodology helps us in the construction of models with different resolutions (base and

  17. Spatial variability in the soil water content of a Mediterranean agroforestry system with high soil heterogeneity

    NASA Astrophysics Data System (ADS)

    Molina, Antonio Jaime; Llorens, Pilar; Aranda, Xavier; Savé, Robert; Biel, Carmen

    2013-04-01

    Variability of soil water content is known to increase with the size of spatial domain in which measurements are taken. At field scale, heterogeneity in soil, vegetation, topography, water input volume and management affects, among other factors, hydrologic plot behaviour under different mean soil water contents. The present work studies how the spatial variability of soil water content (SWC) is affected by soil type (texture, percentage of stones and the combination of them) in a timber-orientated plantation of cherry tree (Prunus avium) under Mediterranean climatic conditions. The experimental design is a randomized block one with 3 blocks * 4 treatments, based on two factors: irrigation (6 plots irrigated versus 6 plots not irrigated) and soil management (6 plots tillaged versus 6 plots not tillaged). SWC is continuously measured at 25, 50 and 100 cm depth with FDR sensors, located at two positions in each treatment: under tree influence and 2.5 m apart. This study presents the results of the monitoring during 2012 of the 24 sensors located at the 25 cm depth. In each of the measurement point, texture and percentage of stones were measured. Sandy-loam, sandy-clay-loam and loam textures were found together with a percentage of stones ranging from 20 to 70 %. The results indicated that the relationship between the daily mean SWC and its standard deviation, a common procedure used to study spatial variability, changed with texture, percentage of stones and the estimation of field capacity from the combination of both. Temporal stability analysis of SWC showed a clear pattern related to field capacity, with the measurement points of the sandy-loam texture and the high percentage of stones showing the maximun negative diference with the global mean. The high range in the mean relative difference observed (± 75 %), could indicate that the studied plot may be considered as a good field-laboratory to extrapolate results at higher spatial scales. Furthermore, the

  18. Heterogeneity in a communal cattle-farming system in a zone endemic for foot and mouth disease in South Africa.

    PubMed

    Van Schalkwyk, Ockert Louis; De Clercq, Eva M; De Pus, Claudia; Hendrickx, Guy; Van den Bossche, Peter; Knobel, Darryn L

    2016-01-01

    In South Africa, communal livestock farming is predominant in the foot and mouth disease control zone adjacent to the Greater Kruger National Park (KNP), where infected African buffaloes are common. During routine veterinary inspections of cattle in this area, a large amount of production and demographic parameters were being recorded. These data were collated for a five-year period (2003-2007) in three study sites to better understand the temporal dynamics and spatial heterogeneity in this system. A decreasing gradient from South to North with respect to both human and cattle population densities was observed. Rainfall and human population density alone could explain 71% of the variation in cattle density. Northern and central sites showed an overall decrease in total cattle numbers (15.1 and 2.9%, respectively), whereas a 28.6% increase was recorded in the South. The number of cattle owners in relation to cattle numbers remained stable during the study period. Only 4.0% of households in the South own cattle, compared to 13.7 and 12.7% in the North and Centre. The overall annual calving rate was 23.8%. Annual mortality rates ranged from 2.4 to 3.2%. Low calf mortality (2.1%) was recorded in the North compared to the South (11.6%). Annual off-take in the form of slaughter averaged 0.2, 11.7, and 11.0% in the North, Central and South sites, respectively. These figures provide valuable baseline data and demonstrate considerable spatial heterogeneity in cattle demography and production at this wildlife-livestock interface, which should be taken into consideration when performing disease risk assessments or designing disease control systems. PMID:27245790

  19. Lithological and hydrological influences on ground-water composition in a heterogeneous carbonate-clay aquifer system

    USGS Publications Warehouse

    Kauffman, S.J.; Herman, J.S.; Jones, B.F.

    1998-01-01

    The influence of clay units on ground-water composition was investigated in a heterogeneous carbonate aquifer system of Miocene age in southwest Florida, known as the Intermediate aquifer system. Regionally, the ground water is recharged inland, flows laterally and to greater depths in the aquifer systems, and is discharged vertically upward at the saltwater interface along the coast. A depth profile of water composition was obtained by sampling ground water from discrete intervals within the permeable carbonate units during coring and by squeezing pore water from a core of the less-permeable clay layers. A normative salt analysis of solute compositions in the water indicated a marine origin for both types of water and an evolutionary pathway for the clay water that involves clay diagenesis. The chemical composition of the ground water in the carbonate bedrock is significantly different from that of the pore water in the clay layers. Dissolution of clays and opaline silica results in high silica concentrations relative to water in other parts of the Intermediate aquifer system. Water enriched in chloride relative to the overlying and underlying ground water recharges the aquifer inland where the confining clay layer is absent, and it dissolves carbonate and silicate minerals and reacts with clays along its flow path, eventually reaching this coastal site and resulting in the high chloride and silica concentrations observed in the middle part of the Intermediate aquifer system. Reaction-path modeling suggests that the recharging surficial water mixes with sulfate-rich water upwelling from the Upper Floridan aquifer, and carbonate mineral dissolution and precipitation, weathering and exchange reactions, clay mineral diagenesis, clay and silica dissolution, organic carbon oxidation, and iron and sulfate reduction result in the observed water compositions.A study was conducted to clarify the influence of clay units on ground-water composition in a heterogeneous

  20. Lewis Carroll's Doublets Net of English Words: Network Heterogeneity in a Complex System

    PubMed Central

    Fushing, Hsieh; Chen, Chen; Hsieh, Yin-Chen; Farrell, Patrick

    2014-01-01

    Lewis Carroll's English word game Doublets is represented as a system of networks with each node being an English word and each connectivity edge confirming that its two ending words are equal in letter length, but different by exactly one letter. We show that this system, which we call the Doublets net, constitutes a complex body of linguistic knowledge concerning English word structure that has computable multiscale features. Distributed morphological, phonological and orthographic constraints and the language's local redundancy are seen at the node level. Phonological communities are seen at the network level. And a balancing act between the language's global efficiency and redundancy is seen at the system level. We develop a new measure of intrinsic node-to-node distance and a computational algorithm, called community geometry, which reveal the implicit multiscale structure within binary networks. Because the Doublets net is a modular complex cognitive system, the community geometry and computable multi-scale structural information may provide a foundation for understanding computational learning in many systems whose network structure has yet to be fully analyzed. PMID:25517974

  1. Emerging Approaches to the Integration of Autonomous Heterogeneous Air Quality Information Systems

    NASA Astrophysics Data System (ADS)

    Husar, R. B.; Scheffe, R.

    2006-12-01

    Data on atmospheric composition relevant to air quality are collected by numerous organizations through a variety of surface and based and remote sensors. The users of such data include managers, scientist and educators, also spread over the many organizations as they participate in broad programs and pursue specific projects. Emerging IS architectures, and technologies now offer the opportunity to augment the traditional end- to-end `stovepipe' information systems. Standards-based data access opens the data flow for networking and leads to reuse. Modularizing data processing components encourages broader participation and software reuse by lowering the entry threshold. The use of workflow software for the creation of applications tends to at `flatten' information systems by ignoring organizational boundaries. The full value of these emerging developments is hard to evaluate at this time but in principle they offer the possibilities for integrating future air quality information systems. Application examples and major impediments will be discussed.

  2. A vector-product information retrieval system adapted to heterogeneous, distributed computing environments

    NASA Technical Reports Server (NTRS)

    Rorvig, Mark E.

    1991-01-01

    Vector-product information retrieval (IR) systems produce retrieval results superior to all other searching methods but presently have no commercial implementations beyond the personal computer environment. The NASA Electronic Library Systems (NELS) provides a ranked list of the most likely relevant objects in collections in response to a natural language query. Additionally, the system is constructed using standards and tools (Unix, X-Windows, Notif, and TCP/IP) that permit its operation in organizations that possess many different hosts, workstations, and platforms. There are no known commercial equivalents to this product at this time. The product has applications in all corporate management environments, particularly those that are information intensive, such as finance, manufacturing, biotechnology, and research and development.

  3. Modeling and simulation of heterogeneous electronic system based on smart sensors for aerospace structures health monitoring

    NASA Astrophysics Data System (ADS)

    Álvarez, Paula L.; Aragonés, Raúl; Oliver, Joan; Ferrer, Carles

    2010-04-01

    This paper presents a top-down design methodology for a behavioral modeling System, based on smart sensors for aerospace structures monitoring, implemented on a MATLAB/Simulink environment. The modeled acquisition platform in this aeronautic health monitoring systems (AHMS) is built using the following specific sensors: humidity, pressure, temperature, stress and acceleration. For this application it has been implemented frequency acquisition techniques ensuring optimum noise immunity, particularly: a signal acquisition technique based on voltage to frequency converter, capacitance to frequency and frequency to code converters (VtoF-cC, CtoF-cC). The Simulink model presents a high accuracy level in signal acquisition and conditioning compared to the electrical system simulation behavior.

  4. Optimizing groundwater monitoring systems for landfills with random leaks under heterogeneous subsurface conditions

    NASA Astrophysics Data System (ADS)

    Yenigül, N. B.; Elfeki, A. M. M.; van den Akker, C.; Dekking, F. M.

    2013-12-01

    Landfills are one of the most common human activities threatening the natural groundwater quality. The landfill may leak, and the corresponding plumes may contaminate an area, entailing costly remediation measures. The objective of the installation of monitoring systems at landfill sites is to detect the contaminant plumes before they reach the regulatory compliance boundary in order to enable cost-effective counter measures. In this study, a classical decision analysis approach is linked to a stochastic simulation model to determine the optimal groundwater monitoring system given uncertainties due to the hydrogeological conditions and contaminant source characteristics. A Monte Carlo approach is used to incorporate uncertainties. Hydraulic conductivity and the leak location are the random inputs of the simulation model. The design objectives are to: (1) maximize the detection probability, (2) minimize the area of contamination at the time of detection, and (3) minimize the total cost of the monitoring system. A synthetic test case based on a real-world case in the Netherlands is analyzed. The results show that monitoring systems located close to the source are optimal except for the cases with very high unit installation and sampling cost and/or very cheap unit remediation.

  5. Communication interval selection in distributed heterogeneous simulation of large-scale dynamical systems

    NASA Astrophysics Data System (ADS)

    Lucas, Charles E.; Walters, Eric A.; Jatskevich, Juri; Wasynczuk, Oleg; Lamm, Peter T.

    2003-09-01

    In this paper, a new technique useful for the numerical simulation of large-scale systems is presented. This approach enables the overall system simulation to be formed by the dynamic interconnection of the various interdependent simulations, each representing a specific component or subsystem such as control, electrical, mechanical, hydraulic, or thermal. Each simulation may be developed separately using possibly different commercial-off-the-shelf simulation programs thereby allowing the most suitable language or tool to be used based on the design/analysis needs. These subsystems communicate the required interface variables at specific time intervals. A discussion concerning the selection of appropriate communication intervals is presented herein. For the purpose of demonstration, this technique is applied to a detailed simulation of a representative aircraft power system, such as that found on the Joint Strike Fighter (JSF). This system is comprised of ten component models each developed using MATLAB/Simulink, EASY5, or ACSL. When the ten component simulations were distributed across just four personal computers (PCs), a greater than 15-fold improvement in simulation speed (compared to the single-computer implementation) was achieved.

  6. VLab: A Science Gateway for Distributed First Principles Calculations in Heterogeneous High Performance Computing Systems

    ERIC Educational Resources Information Center

    da Silveira, Pedro Rodrigo Castro

    2014-01-01

    This thesis describes the development and deployment of a cyberinfrastructure for distributed high-throughput computations of materials properties at high pressures and/or temperatures--the Virtual Laboratory for Earth and Planetary Materials--VLab. VLab was developed to leverage the aggregated computational power of grid systems to solve…

  7. CHROMIUM ISOTOPE SYSTEMATICS OF ACHONDRITES: CHRONOLOGY AND ISOTOPIC HETEROGENEITY OF THE INNER SOLAR SYSTEM BODIES

    SciTech Connect

    Yamakawa, Akane; Yamashita, Katsuyuki; Makishima, Akio; Nakamura, Eizo

    2010-09-01

    The standard planetary formation models assume that primitive materials, such as carbonaceous chondrites, are the precursor materials of evolved planetesimals. Past chronological studies have revealed that planetesimals of several hundred kilometers in size, such as the Howardite-Eucrite-Diogenite (HED) parent body (Vesta) and angrite parent body, began their differentiation as early as {approx}3 million years of the solar system formation, and continued for at least several million years. However, the timescale of planetesimal formation in distinct regions of the inner solar system, as well as the isotopic characteristics of the reservoirs from which they evolved, remains unclear. Here we present the first report for the precise {sup 53}Mn-{sup 53}Cr ages of monomict ureilites. Chemically separated phases from one monomict ureilite (NWA 766) yielded the Mn-Cr age of 4564.60 {+-} 0.67 Ma, identical within error to the oldest age preserved in other achondrites, such as angrites and eucrites. The {sup 54}Cr isotopic data for this and seven additional bulk ureilites show homogeneous {epsilon}{sup 54}Cr of {approx}-0.9, a value distinct from other achondrites and chondrites. Using the {epsilon}{sup 54}Cr signatures of Earth, Mars, and Vesta (HED), we noticed a linear decrease in the {epsilon}{sup 54}Cr value with the heliocentric distance in the inner region of the solar system. If this trend can be extrapolated into the outer asteroid belt, the {epsilon}{sup 54}Cr signatures of monomict ureilites will place the position of the ureilite parent body at {approx}2.8 AU. These observations imply that the differentiation of achondrite parent bodies began nearly simultaneously at {approx}4565 Ma in different regions of the inner solar system. The distinct {epsilon}{sup 54}Cr value between ureilite and carbonaceous chondrite also implies that a genetic link commonly proposed between the two is unlikely.

  8. Mesoscale modeling and computational simulation studies of the self-assembly of heterogeneous colloidal systems

    NASA Astrophysics Data System (ADS)

    Teich-McGoldrick, Stephanie Leah

    Over the last two decades researchers have advanced the field of colloidal synthesis by developing new synthesis techniques. Colloidal particles are known to self-assemble into various unique architectures. However, there is still no simple rule relating system condition and particle type to achievable self-assembled structures. The goal of this thesis was to use simulation methods to further develop an understanding of how tailoring interparticle interactions and system parameters (such as temperature and concentration) leads to self-assembled structures. The applicability of one specific colloidal system---nanotetrapods---for use as nano-electronic circuit elements is investigated. The electrical response for MESFET and JFET nanotetrapods was determined through Technology Aided Design Tools, and it was determined that nanotetrapods have the potential to be utilized as circuit elements. Monte Carlo simulations provide insight into how proper tuning of particle-particle and particle-substrate interactions result in the assembly of ordered arrays of electrically gated nanotetrapods. We used lattice energy calculations and normal mode analysis (NMA) to investigate the thermodynamic and mechanical stability of binary, ionic colloidal crystals with size ratio 1.0 : 0.8. Based on these methods, theoretical predictions were made regarding the stable crystal structure as a function of potential interaction parameters. We found the normal mode results are in agreement with lattice energy results, and were compared to molecular dynamics simulations to determine the capacity for self-assembly. We found that not all predicted structures are kinetically accessible. Additionally, we investigated the self-assembly of colloidal crystals for one specific interaction parameter as a function of density and temperature, and found that, in addition to the theoretically predicted crystal structure, a second entropically stabilized crystal structure formed at higher temperatures. The

  9. Component-based Construction of Heterogeneous Real-time Systems in BIP

    NASA Astrophysics Data System (ADS)

    Sifakis, Joseph

    We present a framework for the component-based construction of real-time systems. The framework is based on the BIP (Behaviour, Interaction, Priority) semantic model, characterized by a layered representation of components. Compound components are obtained as the composition of atomic components specified by their behaviour and interface, by using connectors and dynamic priorities. Connectors describe structured interactions between atomic components, in terms of two basic protocols: rendezvous and broadcast. Dynamic priorities are used to select amongst possible interactions - in particular, to express scheduling policies.

  10. Effects of Field-Scale Heterogeneity on Plume Behavior and Remediation in Alluvial Aquifer Systems

    NASA Astrophysics Data System (ADS)

    Lee, S.; Labolle, E. M.; Fogg, G. E.

    2002-12-01

    This study examines the effects of various field-scale geologic attributes on plume behavior and efficacy of remediation. Using transition probability geostatistical simulation and core descriptions available from the Lawrence Livermore National Laboratory site, we generate a spectrum of unconditional realizations representing alluvial aquifer systems with different degrees of interconnectedness (connectivity) and volumetric abundance of different facies. Both statistical and spatial measures are used to characterize degree of connectivity of high-K bodies (channel facies) in simulated K fields. The random-walk particle method is used to simulate conservative mass transport under steady-state flow conditions. Spatial and temporal analyses of simulated contaminant plumes explore the relative sensitivity of plume behavior to style of geologic complexity. Two geologic settings (one with high-K embedded in low-K materials and the other with low-K embedded in high-K) are used to evaluate a set of remedial methods for different proportions and corresponding degrees of connectivity. The remedial scenarios include ambient transport (no remediation), pump-and-treat remediation with three different rates of extraction, and two methods of enhanced remediation. Results show a percolation threshold for high-K channel bodies between channel fractions of 0.08 and 0.18. Further, as the volume fraction of high-K channel facies increases (from 0.08 to 0.68), simulated plumes show decreasingly anomalous behavior (e.g., mass holdback resulting in tailing). Results show that the architecture of high permeability units and preferential flow paths are important in controlling groundwater flow in fine-grain dominant systems, and relatively less important in coarse-grain dominant systems. Remedial experiments show total mass remaining in low-K materials after the application of remediation is always greater than the total mass in high-K channel facies at the channel facies volume fraction

  11. Characterization of Paper Heterogeneity

    NASA Astrophysics Data System (ADS)

    Considine, John M.

    Paper and paperboard are the most widely-used green materials in the world because they are renewable, recyclable, reusable, and compostable. Continued and expanded use of these materials and their potential use in new products requires a comprehensive understanding of the variability of their mechanical properties. This work develops new methods to characterize the mechanical properties of heterogeneous materials through a combination of techniques in experimental mechanics, materials science and numerical analysis. Current methods to analyze heterogeneous materials focus on crystalline materials or polymer-crystalline composites, where material boundaries are usually distinct. This work creates a methodology to analyze small, continuously-varying stiffness gradients in 100% polymer systems and is especially relevant to paper materials where factors influencing heterogeneity include local mass, fiber orientation, individual pulp fiber properties, local density, and drying restraint. A unique approach was used to understand the effect of heterogeneity on paper tensile strength. Additional variation was intentionally introduced, in the form of different size holes, and their effect on strength was measured. By modifying two strength criteria, an estimate of strength in the absence of heterogeneity was determined. In order to characterize stiffness heterogeneity, a novel load fixture was developed to excite full-field normal and shear strains for anisotropic stiffness determination. Surface strains were measured with digital image correlation and were analyzed with the VFM (Virtual Fields Method). This approach led to VFM-identified stiffnesses that were similar to values determined by conventional tests. The load fixture and VFM analyses were used to measure local stiffness and local stiffness variation on heterogeneous anisotropic materials. The approach was validated on simulated heterogeneous materials and was applied experimentally to three different paperboards

  12. Towards improved characterization of high-risk releases using heterogeneous indoor sensor systems

    SciTech Connect

    Sreedharan, Priya; Sohn, Michael D.; Nazaroff, William W.; J. Gadgil, Ashok

    2010-06-30

    The sudden release of toxic contaminants that reach indoor spaces can be hazardous to building occupants. For an acutely toxic contaminant, the speed of the emergency response strongly influences the consequences to occupants. The design of a real time sensor system is made challenging both by the urgency and complex nature of the event, and by the imperfect sensors and models available to describe it. In this research, we use Bayesian modeling to combine information from multiple types of sensors to improve the characterization of a release. We discuss conceptual and algorithmic considerations for selecting and fusing information from disparate sensors. To explore system performance, we use both real tracer gas data from experiments in a three story building, along with synthetic data, including information from door position sensors. The added information from door position sensors is found to be useful for many scenarios, but not always. We discuss the physical conditions and design factors that affect these results, such as the influence of the door positions on contaminant transport. We highlight potential benefits of multisensor data fusion, challenges in realizing those benefits, and opportunities for further improvement.

  13. On the Effect of Connectivity on Solute Transport in Spatially Heterogeneous Combined Unsaturated-Saturated Flow Systems

    NASA Astrophysics Data System (ADS)

    Russo, David

    2016-04-01

    Detailed numerical analyses of flow and transport were used to investigate the effect of spatially connected features on the transport in three-dimensional (3-D), spatially heterogeneous, combined vadose zone-groundwater flow systems. Formations with spatially connected fine- and coarse-textured features (SCFT- and SCCT-formations, respectively), representing the10th and the 90th percentiles of the distributions of the formation's hydraulic parameters, respectively, were considered here. Results of the analyses suggest that in steady-state flow, when the unsaturated zone of the combined flow domains is relatively wet, as compared with a Multivariate-Gaussian (MG) formation, spatially connected features may reduce the solute first arrival time, particularly in the SCCT-formation, and may enhance the spreading of the solute breakthrough, particularly in the SCFT-formation. The effect of the spatially connected features on the hydrological response, however, decreases as the unsaturated zone becomes drier. The latter result stems from the decrease in the fraction of the water-filled, pore-space occupied by the connected structures, with decreasing water content. The latter finding also explains the result that the response of more realistic, combined flow systems, whose unsaturated zone is associated with transient flow and relatively low, intermittent water contents, is essentially independent of the spatially connected features of the formations, regardless of their soil texture.

  14. Reductive dechlorination of tetrachloroethylene and trichloroethylene catalyzed by vitamin B{sub 12} in homogeneous and heterogeneous systems

    SciTech Connect

    Burris, D.R.; Smith, M.H.; Delcomyn, C.A.; Roberts, A.L.

    1996-10-01

    The reduction of tetrachloroethylene (PCE) and trichloroethylene (TCE) catalyzed by vitamin B{sub 12} was examined in homogeneous and heterogeneous (B{sub 12} bound to agarose) batch systems using titanium(III) citrate as the bulk reductant. The solution and surface-mediated reaction rates at similar B{sub 12} loadings were comparable, indicating that binding vitamin B{sub 12} to a surface did not lower catalytic activity. No loss in PCE reducing activity was observed with repeated usage of surface-bound vitamin B{sub 12}. Carbon mass recoveries were 81-84% for PCE reduction and 89% for TCE reduction, relative to controls. In addition to sequential hydrogenolysis, a second competing reaction mechanism for the reduction of PCE and TCE by B{sub 12}, reductive {beta}-elimination, is proposed to account for the observation of acetylene as a significant reaction intermediate. Reductive {beta}-elimination should be considered as a potential pathway in other reactive systems involving the reduction of vicinal polyhaloethenes. Surface-bound catalysts such as vitamin B{sub 12} may have utility in the engineered degradation of aqueous phase chlorinated ethenes. 19 refs., 6 figs., 1 tab.

  15. Phase and amplitude dynamics in large systems of coupled oscillators: growth heterogeneity, nonlinear frequency shifts, and cluster states.

    PubMed

    Lee, Wai Shing; Ott, Edward; Antonsen, Thomas M

    2013-09-01

    This paper addresses the behavior of large systems of heterogeneous, globally coupled oscillators each of which is described by the generic Landau-Stuart equation, which incorporates both phase and amplitude dynamics of individual oscillators. One goal of our paper is to investigate the effect of a spread in the amplitude growth parameter of the oscillators and of the effect of a homogeneous nonlinear frequency shift. Both of these effects are of potential relevance to recently reported experiments. Our second goal is to gain further understanding of the macroscopic system dynamics at large coupling strength, and its dependence on the nonlinear frequency shift parameter. It is proven that at large coupling strength, if the nonlinear frequency shift parameter is below a certain value, then there is a unique attractor for which the oscillators all clump at a single amplitude and uniformly rotating phase (we call this a single-cluster "locked state"). Using a combination of analytical and numerical methods, we show that at higher values of the nonlinear frequency shift parameter, the single-cluster locked state attractor continues to exist, but other types of coexisting attractors emerge. These include two-cluster locked states, periodic orbits, chaotic orbits, and quasiperiodic orbits.

  16. Removal of bisphenol derivatives through quinone oxidation by polyphenol oxidase and subsequent quinone adsorption on chitosan in the heterogeneous system.

    PubMed

    Kimura, Yuji; Takahashi, Ayumi; Kashiwada, Ayumi; Yamada, Kazunori

    2015-01-01

    In this study, the combined use of a biopolymer chitosan and an oxidoreductase polyphenol oxidase (PPO) was systematically investigated for the removal of bisphenol derivatives from aqueous medium. The process parameters, such as the pH value, temperature, and PPO concentration, were estimated to conduct the enzymatic quinone oxidation of bisphenol derivatives by as little enzyme as possible. Bisphenol derivatives effectively underwent PPO-catalysed quinone oxidation without H2O2 unlike other oxidoreductases, such as peroxidase and tyrosinase, and the optimum conditions were determined to be pH 7.0 and 40°C for bisphenol B, bisphenol E, bisphenol O, and bisphenol Z; pH 7.0 and 30°C for bisphenol C and bisphenol F; and pH 8.0 and 40°C for bisphenol T. They were completely removed through adsorption of enzymatically generated quinone derivatives on chitosan beads or chitosan powders. Quinone adsorption on chitosan beads or chitosan powders in the heterogeneous system was found to be a more effective procedure than generation of aggregates in the homogeneous system with chitosan solution. The removal time was shortened by increasing the amount of chitosan beads or decreasing the size of the chitosan powders.

  17. Twisting in the excited state of an N-methylpyridinium fluorescent dye modulated by nano-heterogeneous micellar systems.

    PubMed

    Cesaretti, A; Carlotti, B; Gentili, P L; Germani, R; Spalletti, A; Elisei, F

    2016-04-01

    A push-pull N-methylpyridinium fluorescent dye with a pyrenyl group as the electron-donor portion was investigated within the nano-heterogeneous media provided by some micellar systems. The molecule was studied by stationary and time-resolved spectroscopic techniques in spherical micellar solutions and viscoelastic hydrogels, in order to throw light on the role played by twisting in its excited state deactivation. As proven by femtosecond fluorescence up-conversion and transient absorption experiments, the excited state dynamics of the molecule is ruled by charge transfer and twisting processes, which, from the locally excited (LE) state initially populated upon excitation, progressively lead to twisted (TICT) and planar (PICT) intramolecular charge transfer states. The inclusion within micellar aggregates was found to slow down and/or limit the rotation of the molecule with respect to what had previously been observed in water, while its confinement within the hydrophobic domains of the gel matrixes prevents any molecular torsion. The increasing viscosity of the medium, when passing from water to micellar systems, implies that the detected steady-state fluorescence comes from an excited state which is not fully relaxed, as is the case with the TICT state in micelles or the LE state in hydrogels, where the detected emission changes its usual orange colour to yellow.

  18. THE TSUNAMI SERVICE BUS, AN INTEGRATION PLATFORM FOR HETEROGENEOUS SENSOR SYSTEMS

    NASA Astrophysics Data System (ADS)

    Fleischer, J.; Häner, R.; Herrnkind, S.; Kriegel, U.; Schwarting, H.; Wächter, J.

    2009-12-01

    The Tsunami Service Bus (TSB) is the sensor integration platform of the German Indonesian Tsunami Early Warning System (GITEWS) [1]. The primary goal of GITEWS is to deliver reliable tsunami warnings as fast as possible. This is achieved on basis of various sensor systems like seismometers, ocean instrumentation, and GPS stations, all providing fundamental data to support prediction of tsunami wave propagation by the GITEWS warning center. However, all these sensors come with their own proprietary data formats and specific behavior. Also new sensor types might be added, old sensors will be replaced. To keep GITEWS flexible the TSB was developed in order to access and control sensors in a uniform way. To meet these requirements the TSB follows the architectural blueprint of a Service Oriented Architecture (SOA). The integration platform implements dedicated services communicating via a service infrastructure. The functionality required for early warnings is provided by loosely coupled services replacing the "hard-wired" coupling at data level. Changes in the sensor specification are confined to the data level without affecting the warning center. Great emphasis was laid on following the Sensor Web Enablement (SWE) standard [2], specified by the Open Geospatial Consortium (OGC) [3]. As a result the full functionality needed in GITEWS could be achieved by implementing the four SWE services: The Sensor Observation Service for retrieving sensor measurements, the Sensor Alert Service in order to deliver sensor alerts, the Sensor Planning Service for tasking sensors, and the Web Notification Service for conduction messages to various media channels. Beyond these services the TSB also follows SWE Observation & Measurements specifications (O&M) for data encoding and Sensor Model Language (SensorML) for meta information. Moreover, accessing sensors via the TSB is not restricted to GITEWS. Multiple instances of the TSB can be composed to realize federate warning system

  19. Modeling permeability evolution by precipitation and dissolution: from a single-pore channel to heterogeneous multi-pore systems

    NASA Astrophysics Data System (ADS)

    Silin, D.; Molins, S.

    2011-12-01

    , the model needs to account for heterogeneous nucleation and enhanced reactivity of new precipitates rather than uniform reactivity. We evaluate the impact of this pore-scale heterogeneity on the permeability evolution of multi-pore systems by comparing the output to earlier results. Averaging the local velocities and reaction rates over the computational domain yields the correlation between Darcy velocity and effective reaction rates. Tracking the pore-space and flow evolution produces porosity-permeability correlations.

  20. Insights into heterogeneous atmospheric oxidation chemistry through vibrational sum frequency generation studies of tailor-made model systems

    NASA Astrophysics Data System (ADS)

    Voges, Andrea Beth

    2006-04-01

    As surfaces are known to have profound implications for chemical transport, reactivity, and energy budgets in atmospheric environments, we have designed a nonlinear optical sum frequency generation (SFG) system that can be used to study atmospherically relevant heterogeneous chemistry. The aims of this project were two-fold: first, to develop and characterize tailor-made organically coated substrates relevant to tropospheric chemistry and second, carry out kinetic studies that model naturally occurring heterogeneous atmospheric reactions. After construction of the broadband SFG system, we studied siloxane substrates functionalized with organic adlayers. The organic adlayers were specifically chosen to contain environmentally relevant functional groups, namely, an acid-terminated alkyl chain, several ester functionalized alkyl chains, and a non-functionalized alkyl chain. Hydrolysis of methyl ester functionalized surfaces was carried out to produce carboxylic acid functionalized surfaces and monitored using SFG. In order to access more complicated atmospherically relevant substrates, we then focused on the synthesis and characterization of a derivative of limonene, a biogenically emitted compound, chemically bound to a glass surface. We employed both electrophilic, and nucleophilic linker chemistries to increase the versatility of our approach. SFG spectra indicated that while orientation of the surface-bound terpenes depended on the linker strategy we employed, the C=C double bond was accessible to gas phase ozone regardless of the strategy applied. We then used SFG to track the interaction of a terpene-linked species with ozone and calculate reaction probabilities. Exposure of the amide-linked terpene substrate to ppm levels of ozone at a total pressure of 1 atm and 300 K yielded an initial reaction probability of approximately 1 x 10 -5, which was significantly higher than the corresponding gas phase reaction involving 1-methyl-1-cyclohexene. The chemical

  1. Heterogeneous Distribution of ^2^6Al at the Birth of the Solar System: Evidence from Corundum-Bearing Refractory Inclusions

    NASA Astrophysics Data System (ADS)

    Krot, A. N.; Makide, K.; Nagashima, K.; Huss, G. R.; Hellebrand, E.; Petaev, M. I.

    2012-03-01

    Corundum-bearing CAIs recorded heterogeneous distribution of ^2^6Al at the birth of the solar system. We suggest that ^2^6Al was injected into the protosolar molecular cloud core by a wind from a massive star and was later homogenized through the disk.

  2. Heterogeneous Role of the Glutathione Antioxidant System in Modulating the Response of ESFT to Fenretinide in Normoxia and Hypoxia

    PubMed Central

    Magwere, Tapiwanashe; Burchill, Susan A.

    2011-01-01

    Glutathione (GSH) is implicated in drug resistance mechanisms of several cancers and is a key regulator of cell death pathways within cells. We studied Ewing's sarcoma family of tumours (ESFT) cell lines and three mechanistically distinct anticancer agents (fenretinide, doxorubicin, and vincristine) to investigate whether the GSH antioxidant system is involved in the reduced sensitivity to these chemotherapeutic agents in hypoxia. Cell viability and death were assessed by the trypan blue exclusion assay and annexin V-PI staining, respectively. Hypoxia significantly decreased the sensitivity of all ESFT cell lines to fenretinide-induced death, whereas the effect of doxorubicin or vincristine was marginal and cell-line-specific. The response of the GSH antioxidant system in ESFT cell lines to hypoxia was variable and also cell-line-specific, although the level of GSH appeared to be most dependent on de novo biosynthesis rather than recycling. RNAi-mediated knockdown of key GSH regulatory enzymes γ-glutamylcysteine synthetase or glutathione disulfide reductase partially reversed the hypoxia-induced resistance to fenretinide, and increasing GSH levels using N-acetylcysteine augmented the hypoxia-induced resistance in a cell line-specific manner. These observations are consistent with the conclusion that the role of the GSH antioxidant system in modulating the sensitivity of ESFT cells to fenretinide is heterogeneous depending on environment and cell type. This is likely to limit the value of targeting GSH as a therapeutic strategy to overcome hypoxia-induced drug resistance in ESFT. Whether targeting the GSH antioxidant system in conjunction with other therapeutics may benefit some patients with ESFT remains to be seen. PMID:22174837

  3. Heterogeneity of Matrin 3 in the developing and aging murine central nervous system.

    PubMed

    Rayaprolu, Sruti; D'Alton, Simon; Crosby, Keith; Moloney, Christina; Howard, John; Duffy, Colin; Cabrera, Mariela; Siemienski, Zoe; Hernandez, Abigail R; Gallego-Iradi, Carolina; Borchelt, David R; Lewis, Jada

    2016-10-01

    Mutations in the MATR3 gene encoding the nucleotide binding protein Matrin 3 have recently been identified as causing a subset of familial amyotrophic lateral sclerosis (fALS) and more rarely causing distal myopathy. Translating the identification of MATR3 mutations into an understanding of disease pathogenesis and the creation of mouse models requires a complete understanding of normal Matrin 3 levels and distribution in vivo. Consequently, we examined the levels of murine Matrin 3 in body tissues and regions of the central nervous system (CNS). We observed a significant degree of variability in Matrin 3 protein levels among different tissues of adult animals, with the highest levels found in reproductive organs and the lowest in muscle. Within the adult CNS, Matrin 3 levels were lowest in spinal cord. Further, we found that Matrin 3 declines significantly in CNS through early development and young adulthood before stabilizing. As previously reported, antibodies to Matrin 3 primarily stain nuclei, but the intensity of staining was not uniform in all nuclei. The low levels of Matrin 3 in spinal cord and muscle could mean that that these tissues are particularly vulnerable to alterations in Matrin 3 function. Our study is the first to characterize endogenous Matrin 3 in rodents across the lifespan, providing the groundwork for deciphering disease mechanisms and developing mouse models of MATR3-linked ALS. J. Comp. Neurol. 524:2740-2752, 2016. © 2016 Wiley Periodicals, Inc. PMID:26878116

  4. Subsurface high resolution definition of subsurface heterogeneity for understanding the biodynamics of natural field systems: Advancing the ability for scaling to field conditions. 1998 annual progress report

    SciTech Connect

    Majer, E.L.; Brockman, F.J.

    1998-06-01

    'This research is an integrated physical (geophysical and hydrologic) and microbial study using innovative geophysical imaging and microbial characterization methods to identify key scales of physical heterogeneities that affect the biodynamics of natural subsurface environments. Data from controlled laboratory and in-situ experiments at the INEEL Test Area North (TAN) site are being used to determine the dominant physical characteristics (lithologic, structural, and hydrologic) that can be imaged in-situ and correlated with microbial properties. The overall goal of this research is to contribute to the understanding of the interrelationships between transport properties and spatially varying physical, chemical, and microbiological heterogeneity. The outcome will be an improved understanding of the relationship between physical and microbial heterogeneity, thus facilitating the design of bioremediation strategies in similar environments. This report summarizes work as of May 1998, the second year of the project. This work is an extension of basic research on natural heterogeneity first initiated within the DOE/OHER Subsurface Science Program (SSP) and is intended to be one of the building blocks of an integrated and collaborative approach with an INEEL/PNNL effort aimed at understanding the effect of physical heterogeneity on transport properties and biodynamics in natural systems. The work is closely integrated with other EMSP projects at INEEL (Rick Colwell et al.) and PNNL (Fred Brockman and Jim Fredrickson).'

  5. Ferromagnetic resonance of an heterogeneous multilayer system with interlayer exchange coupling: an accessible model

    NASA Astrophysics Data System (ADS)

    Franco, A. F.; Landeros, P.

    2016-09-01

    We present a general model for the coupled magnetic resonances of an exchange interacting multilayer system, which can be implemented without complex analytical calculations or numerical simulations. The model allows one to study the spin wave modes of a multilayer structure with any number of layers, accounting for individual uniaxial and cubic anisotropies, and (static and dynamic) demagnetizing and external fields as well, assuming that only the interlayer exchange coupling mechanism is relevant between such magnetic layers. This scheme is applied to recent measurements of a NiFe/CoFe bilayer, and to studying the influence of the strength of ferromagnetic and antiferromagnetic exchange interactions and the applied field orientation on the spin wave modes and intensities of the ferromagnetic resonance response. We find that the acoustic oscillation mode tends to stabilize in frequency if the magnetizations of the layers are parallel to each other, while the optical mode stabilizes when the magnetizations are antiparallel. Furthermore, we find that each oscillation mode is governed by either the NiFe or the CoFe. The modes swap the governing layer as the perpendicular field increases, inducing a gap between their frequencies, which appears to be proportional to the exchange coupling. Finally, we find that the field linewidth of the bilayer due to Gilbert damping has a dependence on the frequency very similar to the linear dependence of the linewidth in single layers. The theoretical scheme presented here can be further used to explore magnetization dynamics in different multilayer architectures—such as exchange springs, structures with perpendicular magnetic anisotropy, and complex compositions of layer stacks—and can be useful as a basis to study multilayers with chiral and dipolar interactions.

  6. Query Expansion Using Heterogeneous Thesauri.

    ERIC Educational Resources Information Center

    Mandala, Rila; Tokunaga, Takenobu; Tanaka, Hozumi

    2000-01-01

    Proposes a method to improve the performance of information retrieval systems by expanding queries using heterogeneous thesauri. Experiments show that using heterogeneous thesauri with an appropriate weighting method results in better retrieval performance than using only one type of thesaurus. (Author/LRW)

  7. XSTREAM: A Highly Efficient High Speed Real-time Satellite Data Acquisition and Processing System using Heterogeneous Computing

    NASA Astrophysics Data System (ADS)

    Pramod Kumar, K.; Mahendra, P.; Ramakrishna rReddy, V.; Tirupathi, T.; Akilan, A.; Usha Devi, R.; Anuradha, R.; Ravi, N.; Solanki, S. S.; Achary, K. K.; Satish, A. L.; Anshu, C.

    2014-11-01

    In the last decade, the remote sensing community has observed a significant growth in number of satellites, sensors and their resolutions, thereby increasing the volume of data to be processed each day. Satellite data processing is a complex and time consuming activity. It consists of various tasks, such as decode, decrypt, decompress, radiometric normalization, stagger corrections, ephemeris data processing for geometric corrections etc., and finally writing of the product in the form of an image file. Each task in the processing chain is sequential in nature and has different computing needs. Conventionally the processes are cascaded in a well organized workflow to produce the data products, which are executed on general purpose high-end servers / workstations in an offline mode. Hence, these systems are considered to be ineffective for real-time applications that require quick response and just-intime decision making such as disaster management, home land security and so on. This paper discusses anovel approach to processthe data online (as the data is being acquired) using a heterogeneous computing platform namely XSTREAM which has COTS hardware of CPUs, GPUs and FPGA. This paper focuses on the process architecture, re-engineering aspects and mapping of tasks to the right computing devicewithin the XSTREAM system, which makes it an ideal cost-effective platform for acquiring, processing satellite payload data in real-time and displaying the products in original resolution for quick response. The system has been tested for IRS CARTOSAT and RESOURCESAT series of satellites which have maximum data downlink speed of 210 Mbps.

  8. Adaptive Traffic Route Control in QoS Provisioning for Cognitive Radio Technology with Heterogeneous Wireless Systems

    NASA Astrophysics Data System (ADS)

    Yamamoto, Toshiaki; Ueda, Tetsuro; Obana, Sadao

    As one of the dynamic spectrum access technologies, “cognitive radio technology,” which aims to improve the spectrum efficiency, has been studied. In cognitive radio networks, each node recognizes radio conditions, and according to them, optimizes its wireless communication routes. Cognitive radio systems integrate the heterogeneous wireless systems not only by switching over them but also aggregating and utilizing them simultaneously. The adaptive control of switchover use and concurrent use of various wireless systems will offer a stable and flexible wireless communication. In this paper, we propose the adaptive traffic route control scheme that provides high quality of service (QoS) for cognitive radio technology, and examine the performance of the proposed scheme through the field trials and computer simulations. The results of field trials show that the adaptive route control according to the radio conditions improves the user IP throughput by more than 20% and reduce the one-way delay to less than 1/6 with the concurrent use of IEEE802.16 and IEEE802.11 wireless media. Moreover, the simulation results assuming hundreds of mobile terminals reveal that the number of users receiving the required QoS of voice over IP (VoIP) service and the total network throughput of FTP users increase by more than twice at the same time with the proposed algorithm. The proposed adaptive traffic route control scheme can enhance the performances of the cognitive radio technologies by providing the appropriate communication routes for various applications to satisfy their required QoS.

  9. Heterogeneity of guinea-pig caseins synthesized and sequestered by cell-free protein-synthesizing systems.

    PubMed Central

    Pascall, J C; Boulton, A P; Parker, D; Hall, L; Craig, R K

    1981-01-01

    1. Individual mRNA species encoding guinea-pigs caseins A, B and C, and alpha-lactalbumin, were purified by hydridization to recombinant milk-protein plasmid DNA immobilized on diazobenzyloxymethyl-paper or diazobenzyloxymethyl-cellulose. Addition of the purified mRNA species to a reticulocyte-lysate cell-free system, in the presence or absence of a dog pancreas microsomal membrane fraction, established a precursor-product relationship between the primary translation products and those sequestered within microsomal vesicles, as determined by polyacrylamide-gel analysis in one and two dimensions. 2. Three sequestered variants of sequestered casein A were identified, but only single forms of sequestered casein B and alpha-lactalbumin. Sequestered variants of casein C proved to be unexpectedly basic, and did not focus on the pH gradient utilized. 3. Comparative analysis of milk proteins synthesized in the reticulocyte-lysate and wheat-germ cell-free systems by two-dimensional gel electrophoresis demonstrated both quantitative and qualitative differences. In particular, marked but variable heterogeneity was apparent within the primary translation products of casein A and casein B. Pre-casein C did not focus. Limited N-terminal processing of the primary translation products was also evident. These observations are discussed in relation to (i) unscheduled post-translational modifications by cell-free protein-synthesizing systems and (ii) multiplicity of signal sequences. 4. Overall we demonstrate that complex precursor-product relationships between primary translation products and their sequestered variants, programmed in vitro by a mixed mRNA population, may be readily analysed by using individual mRNA sequences purified by hybridization to immobilized cloned complementary-DNA sequences. Images Fig. 1. Fig. 2. Fig. 3. Fig. 4. Fig. 5. PMID:7316995

  10. Deducing transmissivity from specific capacity in the heterogeneous upper aquifer system of Jifarah Plain, NW-Libya

    NASA Astrophysics Data System (ADS)

    Al Farrah, Nawal; Van Camp, Marc; Walraevens, Kristine

    2013-09-01

    The hydraulic characterisation of aquifer systems is important for the development of exploitation scenarios and management strategies. Especially in lithologically heterogeneous aquifers, local scale variations in transmissivity (T) may not be neglected. Field scale transmissivity values are usually derived from pumping tests, but in most cases their number and availability is rather limited. Therefore T values are often estimated from specific well capacities (SC) which can easily be measured in exploitation wells based on static and dynamic water levels. Empirical relations allow T to be calculated from SC values using a power law relation of the form T = A * SCN. In this paper this relation is investigated for three aquifers in north-west Lybia, using the results from step-drawdown tests which allow determination of well efficiencies, which can be incorporated into the regression analysis. The obtained fitting coefficients of the power law relations were compared with published values from other studies. Both parameters of the power law relation (scale factor and power coefficient) seem to be highly correlated following an exponential relationship (R2 = 0.89), reducing the T-SC relation to a single parameter equation, which is mainly related to lithology.

  11. A heterogeneous system based on GPU and multi-core CPU for real-time fluid and rigid body simulation

    NASA Astrophysics Data System (ADS)

    da Silva Junior, José Ricardo; Gonzalez Clua, Esteban W.; Montenegro, Anselmo; Lage, Marcos; Dreux, Marcelo de Andrade; Joselli, Mark; Pagliosa, Paulo A.; Kuryla, Christine Lucille

    2012-03-01

    Computational fluid dynamics in simulation has become an important field not only for physics and engineering areas but also for simulation, computer graphics, virtual reality and even video game development. Many efficient models have been developed over the years, but when many contact interactions must be processed, most models present difficulties or cannot achieve real-time results when executed. The advent of parallel computing has enabled the development of many strategies for accelerating the simulations. Our work proposes a new system which uses some successful algorithms already proposed, as well as a data structure organisation based on a heterogeneous architecture using CPUs and GPUs, in order to process the simulation of the interaction of fluids and rigid bodies. This successfully results in a two-way interaction between them and their surrounding objects. As far as we know, this is the first work that presents a computational collaborative environment which makes use of two different paradigms of hardware architecture for this specific kind of problem. Since our method achieves real-time results, it is suitable for virtual reality, simulation and video game fluid simulation problems.

  12. Comparison of Different Upscaling Methods for Predicting Thermal Conductivity of Complex Heterogeneous Materials System: Application on Nuclear Waste Forms

    SciTech Connect

    Li, Dongsheng; Sun, Xin; Khaleel, Mohammad A.

    2012-06-16

    To develop a strategy in thermal conductivity prediction of a complex heterogeneous materials system, loaded nuclear waste forms, the computational efficiency and accuracy of different upscaling methods have been evaluated. The effective thermal conductivity, obtained from microstructure information and local thermal conductivity of different components, is critical in predicting the life and performance of waste form during storage. Several methods, including the Taylor model, Sachs model, self-consistent model, and statistical upscaling method, were developed and implemented. Microstructure based finite element method (FEM) prediction results were used to as benchmark to determine the accuracy of the different upscaling methods. Micrographs from waste forms with varying waste loadings were used in the prediction of thermal conductivity in FEM and homogenization methods. Prediction results demonstrated that in term of efficiency, boundary models (e.g., Taylor model and Sachs model) are stronger than the self-consistent model, statistical upscaling method, and finite element method. However, when balancing computational efficiency and accuracy, statistical upscaling is a useful method in predicting effective thermal conductivity for nuclear waste forms.

  13. OH-initiated heterogeneous oxidation of cholestane: a model system for understanding the photochemical aging of cyclic alkane aerosols.

    PubMed

    Zhang, Haofei; Ruehl, Christopher R; Chan, Arthur W H; Nah, Theodora; Worton, David R; Isaacman, Gabriel; Goldstein, Allen H; Wilson, Kevin R

    2013-11-27

    Aerosols containing aliphatic hydrocarbons play a substantial role in the urban atmosphere. Cyclic alkanes constitute a large fraction of aliphatic hydrocarbon emissions originating from incomplete combustion of diesel fuel and motor oil. In the present study, cholestane (C27H48) is used as a model system to examine the OH-initiated heterogeneous oxidation pathways of cyclic alkanes in a photochemical flow tube reactor. Oxidation products are collected on filters and analyzed by a novel soft ionization two-dimensional gas chromatography/mass spectrometry technique. The analysis reveals that the first-generation functionalization products (cholestanones, cholestanals, and cholestanols) are the dominant reaction products that account for up to 70% by mass of the total speciated compounds. The ratio of first-generation carbonyls to alcohols is near unity at every oxidation level. Among the cholestanones/cholestanals, 55% are found to have the carbonyl group on the rings of the androstane skeleton, while 74% of cholestanols have the hydroxyl group on the rings. Particle-phase oxidation products with carbon numbers less than 27 (i.e., "fragmentation products") and higher-generation functionalization products are much less abundant. Carbon bond cleavage was found to occur only on the side chain. Tertiary-carbon alkoxy radicals are suggested to play an important role in governing both the distribution of functionalization products (via alkoxy radical isomerization and reaction with oxygen) and the fragmentation products (via alkoxy radical decomposition). These results provide new insights into the oxidation mechanism of cyclic alkanes.

  14. Adaptive discrete cosine transform-based image compression method on a heterogeneous system platform using Open Computing Language

    NASA Astrophysics Data System (ADS)

    Alqudami, Nasser; Kim, Shin-Dug

    2014-11-01

    Discrete cosine transform (DCT) is one of the major operations in image compression standards and it requires intensive and complex computations. Recent computer systems and handheld devices are equipped with high computing capability devices such as a general-purpose graphics processing unit (GPGPU) in addition to the traditional multicores CPU. We develop an optimized parallel implementation of the forward DCT algorithm for the JPEG image compression using the recently proposed Open Computing Language (OpenCL). This OpenCL parallel implementation combines a multicore CPU and a GPGPU in a single solution to perform DCT computations in an efficient manner by applying certain optimization techniques to enhance the kernel execution time and data movements. A separate optimal OpenCL kernel code was developed (CPU-based and GPU-based kernels) based on certain appropriate device-based optimization factors, such as thread-mapping, thread granularity, vector-based memory access, and the given workload. The performance of DCT is evaluated on a heterogeneous environment and our OpenCL parallel implementation results in speeding up the execution of the DCT by the factors of 3.68 and 5.58 for different image sizes and formats in terms of workload allocations and data transfer mechanisms. The obtained speedup indicates the scalability of the DCT performance.

  15. OH-initiated heterogeneous oxidation of cholestane: a model system for understanding the photochemical aging of cyclic alkane aerosols.

    PubMed

    Zhang, Haofei; Ruehl, Christopher R; Chan, Arthur W H; Nah, Theodora; Worton, David R; Isaacman, Gabriel; Goldstein, Allen H; Wilson, Kevin R

    2013-11-27

    Aerosols containing aliphatic hydrocarbons play a substantial role in the urban atmosphere. Cyclic alkanes constitute a large fraction of aliphatic hydrocarbon emissions originating from incomplete combustion of diesel fuel and motor oil. In the present study, cholestane (C27H48) is used as a model system to examine the OH-initiated heterogeneous oxidation pathways of cyclic alkanes in a photochemical flow tube reactor. Oxidation products are collected on filters and analyzed by a novel soft ionization two-dimensional gas chromatography/mass spectrometry technique. The analysis reveals that the first-generation functionalization products (cholestanones, cholestanals, and cholestanols) are the dominant reaction products that account for up to 70% by mass of the total speciated compounds. The ratio of first-generation carbonyls to alcohols is near unity at every oxidation level. Among the cholestanones/cholestanals, 55% are found to have the carbonyl group on the rings of the androstane skeleton, while 74% of cholestanols have the hydroxyl group on the rings. Particle-phase oxidation products with carbon numbers less than 27 (i.e., "fragmentation products") and higher-generation functionalization products are much less abundant. Carbon bond cleavage was found to occur only on the side chain. Tertiary-carbon alkoxy radicals are suggested to play an important role in governing both the distribution of functionalization products (via alkoxy radical isomerization and reaction with oxygen) and the fragmentation products (via alkoxy radical decomposition). These results provide new insights into the oxidation mechanism of cyclic alkanes. PMID:24152093

  16. Large epidemic thresholds emerge in heterogeneous networks of heterogeneous nodes

    NASA Astrophysics Data System (ADS)

    Yang, Hui; Tang, Ming; Gross, Thilo

    2015-08-01

    One of the famous results of network science states that networks with heterogeneous connectivity are more susceptible to epidemic spreading than their more homogeneous counterparts. In particular, in networks of identical nodes it has been shown that network heterogeneity, i.e. a broad degree distribution, can lower the epidemic threshold at which epidemics can invade the system. Network heterogeneity can thus allow diseases with lower transmission probabilities to persist and spread. However, it has been pointed out that networks in which the properties of nodes are intrinsically heterogeneous can be very resilient to disease spreading. Heterogeneity in structure can enhance or diminish the resilience of networks with heterogeneous nodes, depending on the correlations between the topological and intrinsic properties. Here, we consider a plausible scenario where people have intrinsic differences in susceptibility and adapt their social network structure to the presence of the disease. We show that the resilience of networks with heterogeneous connectivity can surpass those of networks with homogeneous connectivity. For epidemiology, this implies that network heterogeneity should not be studied in isolation, it is instead the heterogeneity of infection risk that determines the likelihood of outbreaks.

  17. Estimation of hydrologic properties of heterogeneous geologic media with an inverse method based on iterated function systems

    SciTech Connect

    Doughty, C.A.

    1996-05-01

    The hydrologic properties of heterogeneous geologic media are estimated by simultaneously inverting multiple observations from well-test data. A set of pressure transients observed during one or more interference tests is compared to the corresponding values obtained by numerically simulating the tests using a mathematical model. The parameters of the mathematical model are varied and the simulation repeated until a satisfactory match to the observed pressure transients is obtained, at which point the model parameters are accepted as providing a possible representation of the hydrologic property distribution. Restricting the search to parameters that represent fractal hydrologic property distributions can improve the inversion process. Far fewer parameters are needed to describe heterogeneity with a fractal geometry, improving the efficiency and robustness of the inversion. Additionally, each parameter set produces a hydrologic property distribution with a hierarchical structure, which mimics the multiple scales of heterogeneity often seen in natural geological media. Application of the IFS inverse method to synthetic interference-test data shows that the method reproduces the synthetic heterogeneity successfully for idealized heterogeneities, for geologically-realistic heterogeneities, and when the pressure data includes noise.

  18. Micron-scale D/H heterogeneity in chondrite matrices: A signature of the pristine solar system water?

    NASA Astrophysics Data System (ADS)

    Piani, Laurette; Robert, François; Remusat, Laurent

    2015-04-01

    Organic matter and hydrous silicates are intimately mixed in the matrix of chondrites and in-situ determination of their individual D/H ratios is therefore challenging. Nevertheless, the D/H ratio of each pure component in this mixture should yield a comprehensible signature of the origin and evolution of water and organic matter in our solar system. We measured hydrogen isotope ratios of organic and hydrous silicates in the matrices of two carbonaceous chondrites (Orgueil CI1 and Renazzo CR2) and one unequilibrated ordinary chondrite (Semarkona, LL3.0). A novel protocol was adopted, involving NanoSIMS imaging of H isotopes of monoatomatic (H-) and molecular (OH-) secondary ions collected at the same location. This allowed the most enriched component with respect to D to be identified in the mixture. Using this protocol, we found that in carbonaceous chondrites the isotopically homogeneous hydrous silicates are mixed with D-rich organic matter. The opposite was observed in Semarkona. Hydrous silicates in Semarkona display highly heterogeneous D/H ratios, ranging from 150 to 1800 ×10-6 (δDSMOW = - 40 to 10 600‰). Organic matter in Semarkona does not show such large isotopic variations. This suggests limited isotopic exchange between the two phases during aqueous alteration. Our study greatly expands the range of water isotopic values measured so far in solar system objects. This D-rich water reservoir was sampled by the LL ordinary chondrite parent body and an estimate (≤9%) of its relative contribution to the D/H ratio of water in Oort cloud family comets is proposed.

  19. Are bad health and pain making us grumpy? An empirical evaluation of reporting heterogeneity in rating health system responsiveness.

    PubMed

    Fiorentini, Gianluca; Ragazzi, Giovanni; Robone, Silvana

    2015-11-01

    In recent years, the concept of responsiveness has been put forward as one desirable measure of the performance of health systems. Responsiveness can be defined as a system's ability to respond to the legitimate expectations of potential users regarding non-health enhancing aspects of care. However, since responsiveness is evaluated by patients on a categorical scale, their self-evaluation can be affected by the phenomenon of reporting heterogeneity. A few studies have investigated how standard socio-demographic characteristics influence the reporting style of patients with regard to responsiveness. However, we are not aware of studies that focus explicitly on the influence that both the patients' state of health and their experiencing of pain have on their reporting style on responsiveness. This paper tries to bridge this gap by using data regarding a sample of about 2500 patients hospitalized in four Local Health Authorities (LHA) in Italy's Emilia-Romagna region between 2010 and 2012. These patients have evaluated 27 different aspects of the quality of care, concerning five domains of responsiveness (communication, privacy, dignity, waiting times and quality of facilities). Data have been stratified into five sub-samples, according to these domains. We estimate a generalized ordered probit model, an extension of the standard ordered probit model which permits the reporting behaviour of respondents to be modelled as a function of certain respondents' characteristics, which in our analysis are represented by the variables "state of health" and "pain". Our results suggest that unhealthier patients and patients experiencing pain are more likely to report a lower level of responsiveness, all other things being equal.

  20. Are bad health and pain making us grumpy? An empirical evaluation of reporting heterogeneity in rating health system responsiveness.

    PubMed

    Fiorentini, Gianluca; Ragazzi, Giovanni; Robone, Silvana

    2015-11-01

    In recent years, the concept of responsiveness has been put forward as one desirable measure of the performance of health systems. Responsiveness can be defined as a system's ability to respond to the legitimate expectations of potential users regarding non-health enhancing aspects of care. However, since responsiveness is evaluated by patients on a categorical scale, their self-evaluation can be affected by the phenomenon of reporting heterogeneity. A few studies have investigated how standard socio-demographic characteristics influence the reporting style of patients with regard to responsiveness. However, we are not aware of studies that focus explicitly on the influence that both the patients' state of health and their experiencing of pain have on their reporting style on responsiveness. This paper tries to bridge this gap by using data regarding a sample of about 2500 patients hospitalized in four Local Health Authorities (LHA) in Italy's Emilia-Romagna region between 2010 and 2012. These patients have evaluated 27 different aspects of the quality of care, concerning five domains of responsiveness (communication, privacy, dignity, waiting times and quality of facilities). Data have been stratified into five sub-samples, according to these domains. We estimate a generalized ordered probit model, an extension of the standard ordered probit model which permits the reporting behaviour of respondents to be modelled as a function of certain respondents' characteristics, which in our analysis are represented by the variables "state of health" and "pain". Our results suggest that unhealthier patients and patients experiencing pain are more likely to report a lower level of responsiveness, all other things being equal. PMID:26387079

  1. vls Antigenic Variation Systems of Lyme Disease Borrelia: Eluding Host Immunity through both Random, Segmental Gene Conversion and Framework Heterogeneity.

    PubMed

    Norris, Steven J

    2014-12-01

    Spirochetes that cause Lyme borreliosis (also called Lyme disease) possess the vls locus, encoding an elaborate antigenic variation system. This locus contains the expression site vlsE as well as a contiguous array of vls silent cassettes, which contain variations of the central cassette region of vlsE. The locus is present on one of the many linear plasmids in the organism, e.g. plasmid lp28-1 in the strain Borrelia burgdorferi B31. Changes in the sequence of vlsE occur continuously during mammalian infection and consist of random, segmental, unidirectional recombination events between the silent cassettes and the cassette region of vlsE. These gene conversion events do not occur during in vitro culture or the tick portion of the infection cycle of B. burgdorferi or the other related Borrelia species that cause Lyme disease. The mechanism of recombination is largely unknown, but requires the RuvAB Holliday junction branch migrase. Other features of the vls locus also appear to be required, including cis locations of vlsE and the silent cassettes and high G+C content and GC skew. The vls system is required for long-term survival of Lyme Borrelia in infected mammals and represents an important mechanism of immune evasion. In addition to sequence variation, immune selection also results in significant heterogeneity in the sequence of the surface lipoprotein VlsE. Despite antigenic variation, VlsE generates a robust antibody response, and both full-length VlsE and the C6 peptide (corresponding to invariant region 6) are widely used in immunodiagnostic tests for Lyme disease.

  2. SU-E-T-626: Accuracy of Dose Calculation Algorithms in MultiPlan Treatment Planning System in Presence of Heterogeneities

    SciTech Connect

    Moignier, C; Huet, C; Barraux, V; Loiseau, C; Sebe-Mercier, K; Batalla, A; Makovicka, L

    2014-06-15

    Purpose: Advanced stereotactic radiotherapy (SRT) treatments require accurate dose calculation for treatment planning especially for treatment sites involving heterogeneous patient anatomy. The purpose of this study was to evaluate the accuracy of dose calculation algorithms, Raytracing and Monte Carlo (MC), implemented in the MultiPlan treatment planning system (TPS) in presence of heterogeneities. Methods: First, the LINAC of a CyberKnife radiotherapy facility was modeled with the PENELOPE MC code. A protocol for the measurement of dose distributions with EBT3 films was established and validated thanks to comparison between experimental dose distributions and calculated dose distributions obtained with MultiPlan Raytracing and MC algorithms as well as with the PENELOPE MC model for treatments planned with the homogenous Easycube phantom. Finally, bones and lungs inserts were used to set up a heterogeneous Easycube phantom. Treatment plans with the 10, 7.5 or the 5 mm field sizes were generated in Multiplan TPS with different tumor localizations (in the lung and at the lung/bone/soft tissue interface). Experimental dose distributions were compared to the PENELOPE MC and Multiplan calculations using the gamma index method. Results: Regarding the experiment in the homogenous phantom, 100% of the points passed for the 3%/3mm tolerance criteria. These criteria include the global error of the method (CT-scan resolution, EBT3 dosimetry, LINAC positionning …), and were used afterwards to estimate the accuracy of the MultiPlan algorithms in heterogeneous media. Comparison of the dose distributions obtained in the heterogeneous phantom is in progress. Conclusion: This work has led to the development of numerical and experimental dosimetric tools for small beam dosimetry. Raytracing and MC algorithms implemented in MultiPlan TPS were evaluated in heterogeneous media.

  3. Heterogeneous distribution of 26Al at the birth of the solar system: Evidence from refractory grains and inclusions

    NASA Astrophysics Data System (ADS)

    Krot, A. N.; Makide, K.; Nagashima, K.; Huss, G. R.; Ogliore, R. C.; Ciesla, F. J.; Yang, L.; Hellebrand, E.; Gaidos, E.

    2012-12-01

    Abstract-We review recent results on O- and Mg-isotope compositions of refractory grains (corundum, hibonite) and calcium, aluminum-rich inclusions (CAIs) from unequilibrated ordinary and carbonaceous chondrites. We show that these refractory objects originated in the presence of nebular gas enriched in 16O to varying degrees relative to the standard mean ocean water value: the Δ17OSMOW value ranges from approximately -16‰ to -35‰, and recorded <span class="hlt">heterogeneous</span> distribution of 26Al in their formation region: the inferred (26Al/27Al)0 ranges from approximately 6.5 × 10-5 to <2 × 10-6. There is no correlation between O- and Mg-isotope compositions of the refractory objects: 26Al-rich and 26Al-poor refractory objects have similar O-isotope compositions. We suggest that 26Al was injected into the 26Al-poor collapsing protosolar molecular cloud core, possibly by a wind from a neighboring massive star, and was later homogenized in the protoplanetary disk by radial mixing, possibly at the canonical value of 26Al/27Al ratio (approximately 5 × 10-5). The 26Al-rich and 26Al-poor refractory grains and inclusions represent different generations of refractory objects, which formed prior to and during the injection and homogenization of 26Al. Thus, the duration of formation of refractory grains and CAIs cannot be inferred from their 26Al-26Mg systematics, and the canonical (26Al/27Al)0 does not represent the initial abundance of 26Al in the solar <span class="hlt">system</span>; instead, it may or may not represent the average abundance of 26Al in the fully formed disk. The latter depends on the formation time of CAIs with the canonical 26Al/27Al ratio relative to the timing of complete delivery of stellar 26Al to the solar <span class="hlt">system</span>, and the degree of its subsequent homogenization in the disk. The injection of material containing 26Al resulted in no observable changes in O-isotope composition of the solar <span class="hlt">system</span>. Instead, the variations in O-isotope compositions between individual</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/24960175','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/24960175"><span id="translatedtitle">Role of subcolloidal (nanosized) precursor species in the early stage of the crystallization of zeolites in <span class="hlt">heterogeneous</span> <span class="hlt">systems</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Ren, Nan; Bosnar, Sanja; Bronić, Josip; Dutour Sikirić, Maja; Mišić, Tea; Svetličić, Vesna; Mao, Jian-Jiang; Antonić Jelić, Tatjana; Hadžija, Mirko; Subotić, Boris</p> <p>2014-07-22</p> <p>A critical analysis was carried out for the purpose of understanding the role of subcolloidal (nanosized) (alumino)silicate precursor species in the early stage of crystallization of zeolites in <span class="hlt">heterogeneous</span> <span class="hlt">systems</span> (hydrogels). The formation and evolution of these subcolloidal species in both the solid and the liquid phases were investigated by various experimental methods such a scanning electron microscopy (SEM, FE-SEM), transmission electron microscopy, atomic force microscopy, particle size analysis, pH measurement, atomic absorption spectroscopy, and dynamic light scattering, after careful separation of intermediates from reaction mixture by two-step centrifugation treatment. The results revealed that a chain of processes (i) the formation of low-molecular-weight (LMW) silicate species, by dissolution of Al-enriched amorphous silica, and their aggregation into about 3 nm sized primary precursor species (PPSs), (ii) the formation of larger (∼3 to ∼15 nm sized) silicate precursor species (LSPSs) by a rapid aggregation/coalescence of PPSs, (iii) the formation of "gel" (primary amorphous precursor) by a random aggregation of LSPSs at room temperature, and (iv) the formation of the worm-like particles (secondary amorphous precursor) occurred in the solid phase during heating of the reaction mixture (hydrogel) from room temperature to 170 °C. It is interesting that almost the same processes occur in the liquid phase but with decreased rate according to the relative low concentration of LMW silicate species. With the above described findings, it is highly expected that the manipulation of crystallization pathway through controlling the formation/evolution of precursor species in the initial stage of the process can be achieved. PMID:24960175</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/13564','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/13564"><span id="translatedtitle">Subsurface high-resolution definition of subsurface <span class="hlt">heterogeneity</span> for understanding the biodynamics of natural field <span class="hlt">systems</span>: Advancing the ability for scaling to field conditions. 1997 annual progress report</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Majer, E.L.</p> <p>1997-01-01</p> <p>'This research is an integrated physical (geophysical and hydrologic) and microbial study using innovative geophysical imaging and microbial characterization methods to identify key scales of physical <span class="hlt">heterogeneities</span> that affect the biodynamics of natural subsurface environments. Data from controlled laboratory and in situ experiments at the INEEL Test Area North (TAN) site are being used to determine the dominant physical characteristics (lithologic, structural, and hydrologic) that can be imaged in situ and correlated with microbial properties. Emphasis is being placed on identifying fundamental scales of variation of physical parameters that control transport behavior relative to predicting subsurface microbial dynamics. The outcome will be an improved understanding of the relationship between physical and microbial <span class="hlt">heterogeneity</span>, thus facilitating the design of bioremediation strategies in similar environments. This work is an extension of basic research on natural <span class="hlt">heterogeneity</span> first initiated within the DOE/OHER Subsurface Science Program (SSP) and is intended to be one of the building blocks of an integrated and collaborative approach with an INEEL/PNNL effort aimed at understanding the effect of physical <span class="hlt">heterogeneity</span> on transport properties and biodynamics in natural <span class="hlt">systems</span>. The work is closely integrated with other EMSP projects at INEEL (Rick Colwell et al.) and PNNL (Fred Brockman and Jim Fredrickson).'</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008SPIE.6974E..0AL','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008SPIE.6974E..0AL"><span id="translatedtitle">A <span class="hlt">heterogeneous</span> sensor network simulation <span class="hlt">system</span> with integrated terrain data for real-time target detection in 3D space</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lin, Hong; Tanner, Steve; Rushing, John; Graves, Sara; Criswell, Evans</p> <p>2008-03-01</p> <p>Large scale sensor networks composed of many low-cost small sensors networked together with a small number of high fidelity position sensors can provide a robust, fast and accurate air defense and warning <span class="hlt">system</span>. The team has been developing simulations of such large networks, and is now adding terrain data in an effort to provide more realistic analysis of the approach. This work, a <span class="hlt">heterogeneous</span> sensor network simulation <span class="hlt">system</span> with integrated terrain data for real-time target detection in a three-dimensional environment is presented. The sensor network can be composed of large numbers of low fidelity binary and bearing-only sensors, and small numbers of high fidelity position sensors, such as radars. The binary and bearing-only sensors are randomly distributed over a large geographic region; while the position sensors are distributed evenly. The elevations of the sensors are determined through the use of DTED Level 0 dataset. The targets are located through fusing measurement information from all types of sensors modeled by the simulation. The network simulation utilizes the same search-based optimization algorithm as in our previous two-dimensional sensor network simulation with some significant modifications. The fusion algorithm is parallelized using spatial decomposition approach: the entire surveillance area is divided into small regions and each region is assigned to one compute node. Each node processes sensor measurements and terrain data only for the assigned sub region. A master process combines the information from all the compute nodes to get the overall network state. The simulation results have indicated that the distributed fusion algorithm is efficient enough so that an optimal solution can be reached before the arrival of the next sensor data with a reasonable time interval, and real-time target detection can be achieved. The simulation was performed on a Linux cluster with communication between nodes facilitated by the Message Passing Interface</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/838864','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/838864"><span id="translatedtitle">Industrial Membrane Filtration and Short-bed Fractal Separation <span class="hlt">Systems</span> for Separating Monomers from <span class="hlt">Heterogeneous</span> Plant Material</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Kearney, M; Kochergin, V; Hess, R; Foust, T; Herbst, R; Mann, N</p> <p>2005-03-31</p> <p>Large-scale displacement of petroleum will come from low-cost cellulosic feedstocks such as straw and corn stover crop residues. This project has taken a step toward making this projection a reality by reducing capital and energy costs, the two largest cost factors associated with converting cellulosic biomass to chemicals and fuels. The technology exists for using acid or enzyme hydrolysis processes to convert biomass feedstock (i.e., waste cellulose such as straw, corn stover, and wood) into their base monomeric sugar building blocks, which can, in turn, be processed into chemicals and fuels using a number of innovative fermentation technologies. However, while these processes are technically possible, practical and economic barriers make these processes only marginally feasible or not feasible at all. These barriers are due in part to the complexity and large fixed and recurring capital costs of unit operations including filtration, chromatographic separation, and ion exchange. This project was designed to help remove these barriers by developing and implementing new purification and separation technologies that will reduce the capital costs of the purification and chromatographic separation units by 50% to 70%. The technologies fundamental to these improvements are: (a) highly efficient clarification and purification <span class="hlt">systems</span> that use screening and membrane filtration to eliminate suspended solids and colloidal material from feed streams and (b) fractal technology based chromatographic separation and ion exchange <span class="hlt">systems</span> that can substitute for conventional <span class="hlt">systems</span> but at much smaller size and cost. A non-hazardous ''raw sugar beet juice'' stream (75 to 100 gal/min) was used for prototype testing of these technologies. This raw beet juice stream from the Amalgamated Sugar LLC plant in Twin Falls, Idaho contained abrasive materials and membrane foulants. Its characteristics were representative of an industrial-scale <span class="hlt">heterogeneous</span> plant extract/hydrolysis stream</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016GMD.....9.3483C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016GMD.....9.3483C"><span id="translatedtitle">Earth <span class="hlt">system</span> modelling on <span class="hlt">system</span>-level <span class="hlt">heterogeneous</span> architectures: EMAC (version 2.42) on the Dynamical Exascale Entry Platform (DEEP)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Christou, Michalis; Christoudias, Theodoros; Morillo, Julián; Alvarez, Damian; Merx, Hendrik</p> <p>2016-09-01</p> <p>We examine an alternative approach to <span class="hlt">heterogeneous</span> cluster-computing in the many-core era for Earth <span class="hlt">system</span> models, using the European Centre for Medium-Range Weather Forecasts Hamburg (ECHAM)/Modular Earth Submodel <span class="hlt">System</span> (MESSy) Atmospheric Chemistry (EMAC) model as a pilot application on the Dynamical Exascale Entry Platform (DEEP). A set of autonomous coprocessors interconnected together, called Booster, complements a conventional HPC Cluster and increases its computing performance, offering extra flexibility to expose multiple levels of parallelism and achieve better scalability. The EMAC model atmospheric chemistry code (Module Efficiently Calculating the Chemistry of the Atmosphere (MECCA)) was taskified with an offload mechanism implemented using OmpSs directives. The model was ported to the MareNostrum 3 supercomputer to allow testing with Intel Xeon Phi accelerators on a production-size machine. The changes proposed in this paper are expected to contribute to the eventual adoption of Cluster-Booster division and Many Integrated Core (MIC) accelerated architectures in presently available implementations of Earth <span class="hlt">system</span> models, towards exploiting the potential of a fully Exascale-capable platform.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2004AGUFM.U41A0715M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2004AGUFM.U41A0715M"><span id="translatedtitle">Scales of mantle <span class="hlt">heterogeneity</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Moore, J. C.; Akber-Knutson, S.; Konter, J.; Kellogg, J.; Hart, S.; Kellogg, L. H.; Romanowicz, B.</p> <p>2004-12-01</p> <p>A long-standing question in mantle dynamics concerns the scale of <span class="hlt">heterogeneity</span> in the mantle. Mantle convection tends to both destroy (through stirring) and create (through melt extraction and subduction) <span class="hlt">heterogeneity</span> in bulk and trace element composition. Over time, these competing processes create variations in geochemical composition along mid-oceanic ridges and among oceanic islands, spanning a range of scales from extremely long wavelength (for example, the DUPAL anomaly) to very small scale (for example, variations amongst melt inclusions). While geochemical data and seismic observations can be used to constrain the length scales of mantle <span class="hlt">heterogeneity</span>, dynamical mixing calculations can illustrate the processes and timescales involved in stirring and mixing. At the Summer 2004 CIDER workshop on Relating Geochemical and Seismological <span class="hlt">Heterogeneity</span> in the Earth's Mantle, an interdisciplinary group evaluated scales of <span class="hlt">heterogeneity</span> in the Earth's mantle using a combined analysis of geochemical data, seismological data and results of numerical models of mixing. We mined the PetDB database for isotopic data from glass and whole rock analyses for the Mid-Atlantic Ridge (MAR) and the East Pacific Rise (EPR), projecting them along the ridge length. We examined Sr isotope variability along the East Pacific rise by looking at the difference in Sr ratio between adjacent samples as a function of distance between the samples. The East Pacific Rise exhibits an overall bowl shape of normal MORB characteristics, with higher values in the higher latitudes (there is, however, an unfortunate gap in sampling, roughly 2000 km long). These background characteristics are punctuated with spikes in values at various locations, some, but not all of which are associated with off-axis volcanism. A Lomb-Scargle periodogram for unevenly spaced data was utilized to construct a power spectrum of the scale lengths of <span class="hlt">heterogeneity</span> along both ridges. Using the same isotopic <span class="hlt">systems</span> (Sr, Nd</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016IJC....89.1203M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016IJC....89.1203M"><span id="translatedtitle">Robust scalable stabilisability conditions for large-scale <span class="hlt">heterogeneous</span> multi-agent <span class="hlt">systems</span> with uncertain nonlinear interactions: towards a distributed computing architecture</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Manfredi, Sabato</p> <p>2016-06-01</p> <p>Large-scale dynamic <span class="hlt">systems</span> are becoming highly pervasive in their occurrence with applications ranging from <span class="hlt">system</span> biology, environment monitoring, sensor networks, and power <span class="hlt">systems</span>. They are characterised by high dimensionality, complexity, and uncertainty in the node dynamic/interactions that require more and more computational demanding methods for their analysis and control design, as well as the network size and node <span class="hlt">system</span>/interaction complexity increase. Therefore, it is a challenging problem to find scalable computational method for distributed control design of large-scale networks. In this paper, we investigate the robust distributed stabilisation problem of large-scale nonlinear multi-agent <span class="hlt">systems</span> (briefly MASs) composed of non-identical (<span class="hlt">heterogeneous</span>) linear dynamical <span class="hlt">systems</span> coupled by uncertain nonlinear time-varying interconnections. By employing Lyapunov stability theory and linear matrix inequality (LMI) technique, new conditions are given for the distributed control design of large-scale MASs that can be easily solved by the toolbox of MATLAB. The stabilisability of each node dynamic is a sufficient assumption to design a global stabilising distributed control. The proposed approach improves some of the existing LMI-based results on MAS by both overcoming their computational limits and extending the applicative scenario to large-scale nonlinear <span class="hlt">heterogeneous</span> MASs. Additionally, the proposed LMI conditions are further reduced in terms of computational requirement in the case of weakly <span class="hlt">heterogeneous</span> MASs, which is a common scenario in real application where the network nodes and links are affected by parameter uncertainties. One of the main advantages of the proposed approach is to allow to move from a centralised towards a distributed computing architecture so that the expensive computation workload spent to solve LMIs may be shared among processors located at the networked nodes, thus increasing the scalability of the approach than the network</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016IJMPC..2750106B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016IJMPC..2750106B"><span id="translatedtitle">Automatic classification of lung tumour <span class="hlt">heterogeneity</span> according to a visual-based score <span class="hlt">system</span> in dynamic contrast enhanced CT sequences</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bevilacqua, Alessandro; Baiocco, Serena</p> <p>2016-03-01</p> <p>Computed tomography (CT) technologies have been considered for a long time as one of the most effective medical imaging tools for morphological analysis of body parts. Contrast Enhanced CT (CE-CT) also allows emphasising details of tissue structures whose <span class="hlt">heterogeneity</span>, inspected through visual analysis, conveys crucial information regarding diagnosis and prognosis in several clinical pathologies. Recently, Dynamic CE-CT (DCE-CT) has emerged as a promising technique to perform also functional hemodynamic studies, with wide applications in the oncologic field. DCE-CT is based on repeated scans over time performed after intravenous administration of contrast agent, in order to study the temporal evolution of the tracer in 3D tumour tissue. DCE-CT pushes towards an intensive use of computers to provide automatically quantitative information to be used directly in clinical practice. This requires that visual analysis, representing the gold-standard for CT image interpretation, gains objectivity. This work presents the first automatic approach to quantify and classify the lung tumour <span class="hlt">heterogeneities</span> based on DCE-CT image sequences, so as it is performed through visual analysis by experts. The approach developed relies on the spatio-temporal indices we devised, which also allow exploiting temporal data that enrich the knowledge of the tissue <span class="hlt">heterogeneity</span> by providing information regarding the lesion status.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014EGUGA..16.4338M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014EGUGA..16.4338M"><span id="translatedtitle">Development and testing of a two-dimensional ultrasonic laboratory model <span class="hlt">system</span> for seismic imaging of <span class="hlt">heterogeneous</span> structures</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Mo, Yike; Karaman, Hakki; Greenhalgh, Stewart</p> <p>2014-05-01</p> <p>To tackle the challenges and imaging problems of complex structures, we have recently assembled within the Wave Propagation Lab at ETH Zürich a simple 2D ultrasonic model facility in which the simulated geological structures are constructed from thin (2 mm thickness) metal and plastic sheets, cut and bonded together. The models were used, in full recognition of the similitude relations, to investigate reflections from beneath a low velocity distorting overburden. Besides uniform and irregular near surface layers, flat and dipping interfaces as well as rectangular high and low velocity block inserts were investigated. The experiments entailed the use of a piezoelectric source driven by a pulse amplifier at ultrasonic frequencies (20-300 kHz) to generate Lamb waves in the plate, which are detected by piezoelectric receivers and recorded digitally on a National Instruments recording <span class="hlt">system</span>, under SignalExpress software control. In the lab <span class="hlt">system</span>, a single cycle sinusoidal pulse with a negative onset (5 μs pulse width and 600 V pulse voltage) was selected as the optimized source pulse. Transducers can be placed along the thin edges of the plate in reflection mode (same edge) or transmission mode (opposite edges, or perpendicular edges). Alternatively they can be mounted on the flat planar surface of the plate to simulate a crosshole survey. Data were originally collected in all different recording geometries over a homogenous aluminium model for calibration purposes and to examine wave modes and propagation characteristics. The two dominant Lamb waves recorded are the fundamental symmetric mode (non-dispersive) and the fundamental antisymmetric (flexural) dispersive mode, which is normally absent when the source transducer is located on a model edge but dominant when it is on the flat planar surface of the plate. Only the symmetric Lamb mode can be used as a proxy for 2D propagation in an extended medium (the field situation). Experimental group and phase velocity</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AdWR...86..119H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AdWR...86..119H"><span id="translatedtitle">A random walk solution for modeling solute transport with network reactions and multi-rate mass transfer in <span class="hlt">heterogeneous</span> <span class="hlt">systems</span>: Impact of biofilms</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Henri, Christopher V.; Fernàndez-Garcia, Daniel</p> <p>2015-12-01</p> <p>The interplay between the spatial variability of the aquifer hydraulic properties, mass transfer due to sub-grid <span class="hlt">heterogeneity</span> and chemical reactions often complicates reactive transport simulations. It is well documented that hydro-biochemical properties are ubiquitously <span class="hlt">heterogeneous</span> and that diffusion and slow advection at the sub-grid scale typically leads to the conceptualization of an aquifer as a multi-porosity <span class="hlt">system</span>. Within this context, chemical reactions taking place in mobile/immobile water regions can be substantially different between each other. This paper presents a particle-based method that can efficiently simulate <span class="hlt">heterogeneity</span>, network reactions and multi-rate mass transfer. The approach is based on the development of transition probabilities that describe the likelihood that particles belonging to a given species and mobile/immobile domain at a given time will be transformed into another species and mobile/immobile domain afterwards. The joint effect of mass transfer and sequential degradation is shown to be non-trivial. A characteristic rebound of degradation products can be observed. This late rebound of concentrations is not driven by any change in the flow regime (e.g., pumping ceases in the pump-and-treat remediation strategy) but due to the natural interplay between mass transfer and chemical reactions. To illustrate that the method can simultaneously represent mass transfer, spatially varying properties and network reactions without numerical problems, we have simulated the degradation of tetrachloroethylene (PCE) in a three-dimensional fully <span class="hlt">heterogeneous</span> aquifer subjected to rate-limited mass transfer. Two types of degradation modes were considered to compare the effect of an active biofilm with that of clay pods present in the aquifer. Results of the two scenarios display significantly differences. Biofilms that promote the degradation of compounds in an immobile region are shown to significantly enhance degradation, rapidly producing</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016HESS...20..279K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016HESS...20..279K"><span id="translatedtitle">Aggregation in environmental <span class="hlt">systems</span> - Part 1: Seasonal tracer cycles quantify young water fractions, but not mean transit times, in spatially <span class="hlt">heterogeneous</span> catchments</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kirchner, J. W.</p> <p>2016-01-01</p> <p>Environmental <span class="hlt">heterogeneity</span> is ubiquitous, but environmental <span class="hlt">systems</span> are often analyzed as if they were homogeneous instead, resulting in aggregation errors that are rarely explored and almost never quantified. Here I use simple benchmark tests to explore this general problem in one specific context: the use of seasonal cycles in chemical or isotopic tracers (such as Cl-, δ18O, or δ2H) to estimate timescales of storage in catchments. Timescales of catchment storage are typically quantified by the mean transit time, meaning the average time that elapses between parcels of water entering as precipitation and leaving again as streamflow. Longer mean transit times imply greater damping of seasonal tracer cycles. Thus, the amplitudes of tracer cycles in precipitation and streamflow are commonly used to calculate catchment mean transit times. Here I show that these calculations will typically be wrong by several hundred percent, when applied to catchments with realistic degrees of spatial <span class="hlt">heterogeneity</span>. This aggregation bias arises from the strong nonlinearity in the relationship between tracer cycle amplitude and mean travel time. I propose an alternative storage metric, the young water fraction in streamflow, defined as the fraction of runoff with transit times of less than roughly 0.2 years. I show that this young water fraction (not to be confused with event-based "new water" in hydrograph separations) is accurately predicted by seasonal tracer cycles within a precision of a few percent, across the entire range of mean transit times from almost zero to almost infinity. Importantly, this relationship is also virtually free from aggregation error. That is, seasonal tracer cycles also accurately predict the young water fraction in runoff from highly <span class="hlt">heterogeneous</span> mixtures of subcatchments with strongly contrasting transit-time distributions. Thus, although tracer cycle amplitudes yield biased and unreliable estimates of catchment mean travel times in <span class="hlt">heterogeneous</span></p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/FR-2012-10-11/pdf/2012-24997.pdf','FEDREG'); return false;" href="https://www.gpo.gov/fdsys/pkg/FR-2012-10-11/pdf/2012-24997.pdf"><span id="translatedtitle">77 FR 61786 - Notice Pursuant to the National Cooperative Research and Production Act of 1993-<span class="hlt">Heterogeneous</span>...</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collection.action?collectionCode=FR">Federal Register 2010, 2011, 2012, 2013, 2014</a></p> <p></p> <p>2012-10-11</p> <p>...--<span class="hlt">Heterogeneous</span> <span class="hlt">System</span> Architecture Foundation Notice is hereby given that, on August 31, 2012, pursuant to.... (``the Act''), <span class="hlt">Heterogeneous</span> <span class="hlt">System</span> Architecture Foundation (``HSA Foundation'') has filed written... open industry adoption of the <span class="hlt">heterogeneous</span> <span class="hlt">system</span> architecture and stimulating a free exchange...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3032581','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3032581"><span id="translatedtitle">Unravelling mononuclear phagocyte <span class="hlt">heterogeneity</span></span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Geissmann, Frédéric; Gordon, Siamon; Hume, David A.; Mowat, Allan M.; Randolph, Gwendalyn J.</p> <p>2011-01-01</p> <p>When Ralph Steinman and Zanvil Cohn first described dendritic cells (DCs) in 1973 it took many years to convince the immunology community that these cells were truly distinct from macrophages. Almost four decades later, the DC is regarded as the key initiator of adaptive immune responses; however, distinguishing DCs from macrophages still leads to confusion and debate in the field. Here, Nature Reviews Immunology asks five experts to discuss the issue of <span class="hlt">heterogeneity</span> in the mononuclear phagocyte <span class="hlt">system</span> and to give their opinion on the importance of defining these cells for future research. PMID:20467425</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015GMD.....8..279D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015GMD.....8..279D"><span id="translatedtitle">A coupling alternative to reactive transport simulations for long-term prediction of chemical reactions in <span class="hlt">heterogeneous</span> CO2 storage <span class="hlt">systems</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>De Lucia, M.; Kempka, T.; Kühn, M.</p> <p>2015-02-01</p> <p>Fully coupled, multi-phase reactive transport simulations of CO2 storage <span class="hlt">systems</span> can be approximated by a simplified one-way coupling of hydrodynamics and reactive chemistry. The main characteristics of such <span class="hlt">systems</span>, and hypotheses underlying the proposed alternative coupling, are (i) that the presence of CO2 is the only driving force for chemical reactions and (ii) that its migration in the reservoir is only marginally affected by immobilisation due to chemical reactions. In the simplified coupling, the exposure time to CO2 of each element of the hydrodynamic grid is estimated by non-reactive simulations and the reaction path of one single batch geochemical model is applied to each grid element during its exposure time. In <span class="hlt">heterogeneous</span> settings, analytical scaling relationships provide the dependency of velocity and amount of reactions to porosity and gas saturation. The analysis of TOUGHREACT fully coupled reactive transport simulations of CO2 injection in saline aquifer, inspired to the Ketzin pilot site (Germany), both in homogeneous and <span class="hlt">heterogeneous</span> settings, confirms that the reaction paths predicted by fully coupled simulations in every element of the grid show a high degree of self-similarity. A threshold value for the minimum concentration of dissolved CO2 considered chemically active is shown to mitigate the effects of the discrepancy between dissolved CO2 migration in non-reactive and fully coupled simulations. In real life, the optimal threshold value is unknown and has to be estimated, e.g. by means of 1-D or 2-D simulations, resulting in an uncertainty ultimately due to the process de-coupling. However, such uncertainty is more than acceptable given that the alternative coupling enables using grids of the order of millions of elements, profiting from much better description of <span class="hlt">heterogeneous</span> reservoirs at a fraction of the calculation time of fully coupled models.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014GMDD....7.6217D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014GMDD....7.6217D"><span id="translatedtitle">A coupling alternative to reactive transport simulations for long-term prediction of chemical reactions in <span class="hlt">heterogeneous</span> CO2 storage <span class="hlt">systems</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>De Lucia, M.; Kempka, T.; Kühn, M.</p> <p>2014-09-01</p> <p>Fully-coupled, multi-phase reactive transport simulations of CO2 storage <span class="hlt">systems</span> can be approximated by a simplified one-way coupling of hydrodynamics and reactive chemistry. The main characteristics of such <span class="hlt">systems</span>, and hypotheses underlying the proposed alternative coupling, are (i) that the presence of CO2 is the only driving force for chemical reactions and (ii) that its migration in the reservoir is only marginally affected by immobilization due to chemical reactions. In the simplified coupling, the exposure time to CO2 of each element of the hydrodynamic grid is estimated by non-reactive simulations and the reaction path of one single batch geochemical model is applied to each grid element during its exposure time. In <span class="hlt">heterogeneous</span> settings, analytical scaling relationships provide the dependency of velocity and amount of reactions to porosity and gas saturation. The analysis of TOUGHREACT fully coupled reactive transport simulations of CO2 injection in saline aquifer, inspired to the Ketzin pilot site (Germany), both in homogeneous and <span class="hlt">heterogeneous</span> settings, confirms that the reaction paths predicted by fully coupled simulations in every element of the grid show a high degree of self-similarity. A threshold value for the minimum concentration of dissolved CO2 considered chemically active is showed to mitigate the effects of the discrepancy between dissolved CO2 migration in non-reactive and fully coupled simulations. In real life, the optimal threshold value is unknown and has to be estimated, e.g., by means of 1-D or 2-D simulations, resulting in an uncertainty ultimately due to the process de-coupling. However, such uncertainty is more than acceptable given that the alternative coupling enables using grids in the order of million elements, profiting from much better description of <span class="hlt">heterogeneous</span> reservoirs at a fraction of the calculation time of fully coupled models.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015PhDT.........3S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015PhDT.........3S"><span id="translatedtitle">Design and implementation of PAVEMON: A GIS web-based pavement monitoring <span class="hlt">system</span> based on large amounts of <span class="hlt">heterogeneous</span> sensors data</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Shahini Shamsabadi, Salar</p> <p></p> <p>A web-based PAVEment MONitoring <span class="hlt">system</span>, PAVEMON, is a GIS oriented platform for accommodating, representing, and leveraging data from a multi-modal mobile sensor <span class="hlt">system</span>. Stated sensor <span class="hlt">system</span> consists of acoustic, optical, electromagnetic, and GPS sensors and is capable of producing as much as 1 Terabyte of data per day. Multi-channel raw sensor data (microphone, accelerometer, tire pressure sensor, video) and processed results (road profile, crack density, international roughness index, micro texture depth, etc.) are outputs of this sensor <span class="hlt">system</span>. By correlating the sensor measurements and positioning data collected in tight time synchronization, PAVEMON attaches a spatial component to all the datasets. These spatially indexed outputs are placed into an Oracle database which integrates seamlessly with PAVEMON's web-based <span class="hlt">system</span>. The web-based <span class="hlt">system</span> of PAVEMON consists of two major modules: 1) a GIS module for visualizing and spatial analysis of pavement condition information layers, and 2) a decision-support module for managing maintenance and repair (Mℝ) activities and predicting future budget needs. PAVEMON weaves together sensor data with third-party climate and traffic information from the National Oceanic and Atmospheric Administration (NOAA) and Long Term Pavement Performance (LTPP) databases for an organized data driven approach to conduct pavement management activities. PAVEMON deals with <span class="hlt">heterogeneous</span> and redundant observations by fusing them for jointly-derived higher-confidence results. A prominent example of the fusion algorithms developed within PAVEMON is a data fusion algorithm used for estimating the overall pavement conditions in terms of ASTM's Pavement Condition Index (PCI). PAVEMON predicts PCI by undertaking a statistical fusion approach and selecting a subset of all the sensor measurements. Other fusion algorithms include noise-removal algorithms to remove false negatives in the sensor data in addition to fusion algorithms developed for</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70032052','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70032052"><span id="translatedtitle">Ground-based thermography of fluvial <span class="hlt">systems</span> at low and high discharge reveals potential complex thermal <span class="hlt">heterogeneity</span> driven by flow variation and bioroughness</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Cardenas, M.B.; Harvey, J.W.; Packman, A.I.; Scott, D.T.</p> <p>2008-01-01</p> <p>Temperature is a primary physical and biogeochemical variable in aquatic <span class="hlt">systems</span>. Field-based measurement of temperature at discrete sampling points has revealed temperature variability in fluvial <span class="hlt">systems</span>, but traditional techniques do not readily allow for synoptic sampling schemes that can address temperature-related questions with broad, yet detailed, coverage. We present results of thermal infrared imaging at different stream discharge (base flow and peak flood) conditions using a handheld IR camera. Remotely sensed temperatures compare well with those measured with a digital thermometer. The thermal images show that periphyton, wood, and sandbars induce significant thermal <span class="hlt">heterogeneity</span> during low stages. Moreover, the images indicate temperature variability within the periphyton community and within the partially submerged bars. The thermal <span class="hlt">heterogeneity</span> was diminished during flood inundation, when the areas of more slowly moving water to the side of the stream differed in their temperature. The results have consequences for thermally sensitive hydroelogical processes and implications for models of those processes, especially those that assume an effective stream temperature. Copyright ?? 2008 John Wiley & Sons, Ltd.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li class="active"><span>22</span></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_22 --> <div id="page_23" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li class="active"><span>23</span></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="441"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/20060564','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/20060564"><span id="translatedtitle">Controlled reduction of red mud waste to produce active <span class="hlt">systems</span> for environmental applications: <span class="hlt">heterogeneous</span> Fenton reaction and reduction of Cr(VI).</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Costa, Regina C C; Moura, Flávia C C; Oliveira, Patrícia E F; Magalhães, Fabiano; Ardisson, José D; Lago, Rochel M</p> <p>2010-02-01</p> <p>In this work, controlled reduction of red mud with H(2) was used to produce active <span class="hlt">systems</span> for two different environmental applications, i.e. the <span class="hlt">heterogeneous</span> Fenton reaction and the reduction of Cr(VI). Mössbauer, powder X-ray diffraction, thermal analyses and scanning electron microscopy analyses showed that at different temperatures, i.e. 300, 400, 500 and 600 degrees C, H(2) reduces red mud to different phases, mainly Fe(3)O(4), Fe(0)/Fe(3)O(4) and Fe(0). These Fe phases are dispersed on Al, Si and Ti oxides present in the red mud and show high reactivity towards two environmental applications, i.e. the <span class="hlt">heterogeneous</span> Fenton reaction and the reduction of Cr(VI). Reduction with H(2) at 400 degrees C showed the best results for the oxidation of the model dye methylene blue with H(2)O(2) at neutral pH due to the presence of the composite Fe(0)/Fe(3)O(4). The reduced red mud at 500-600 degrees C produced Fe(0) highly active for the reduction of Cr(VI) in aqueous medium. Another feature of these red mud based <span class="hlt">system</span> is that after deactivation due to extensive use they can be completely regenerated by simple treatment with H(2).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014EGUGA..16.6352E','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014EGUGA..16.6352E"><span id="translatedtitle">Mechanical and lithological controls on the development of <span class="hlt">heterogeneous</span> fault zones: an example from the southern Dead Sea Fault <span class="hlt">System</span>, Israel</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Evans, Siân; Holdsworth, Bob; Imber, Jonny; de Paola, Nicola; Marco, Shmuel; Weinberger, Rami</p> <p>2014-05-01</p> <p>The mechanical weakening processes involved in the development of major crustal fault <span class="hlt">systems</span> have been widely documented, and it is recognised that clay-bearing fault rocks frequently have a significant influence on fault strength and slip behaviour in the upper crust. It is less well-understood how mechanical processes, such as cataclasis and the mechanical entrainment of fault rock materials along fault zones (e.g. "smearing"), interact with chemical processes, such as clay mineral transformations and phyllonitisation during fault rock development. These processes can combine to form fault zones that may be both lithologically and mechanically <span class="hlt">heterogeneous</span>, and which may also evolve over time, changing the nature of observed <span class="hlt">heterogeneities</span>. We present here data from exhumed sections of the southern Dead Sea Fault <span class="hlt">System</span>, Israel, an active continental transform fault that has accumulated 105 km of sinistral displacement since the mid-Miocene. These faults are estimated to have been active at shallow depths (<5 km, but potentially significantly less. The so-called "fault cores" of these sections are highly <span class="hlt">heterogeneous</span> and are comprised of material formed by a variety of processes: fault gouges formed by cataclasis; coarser-grained, variably crushed crystalline basement rocks; mechanically entrained highly mobile units, derived from shale in adjacent cover sequence wall rocks; and growth of authegenic mineral phases through alteration and pressure solution. Through operation of grain-size reduction and diffusive mass transfer processes, we see a bulk change from fault rocks dominated by relatively strong phases displaying no obvious fabric, such as feldspars and calcite, through to foliated phyllosilicate-rich (illite, chlorite, smectite) fault rocks which likely have much lower frictional strengths. Mechanically entrained shale that has not undergone significant brittle deformation can also efficiently introduce large volumes of relatively weak material into</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2245763','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2245763"><span id="translatedtitle"><span class="hlt">Heterogeneity</span> in Health Care Computing Environments</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Sengupta, Soumitra</p> <p>1989-01-01</p> <p>This paper discusses issues of <span class="hlt">heterogeneity</span> in computer <span class="hlt">systems</span>, networks, databases, and presentation techniques, and the problems it creates in developing integrated medical information <span class="hlt">systems</span>. The need for institutional, comprehensive goals are emphasized. Using the Columbia-Presbyterian Medical Center's computing environment as the case study, various steps to solve the <span class="hlt">heterogeneity</span> problem are presented.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3797472','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3797472"><span id="translatedtitle">Spatial phenotypic and genetic structure of threespine stickleback (Gasterosteus aculeatus) in a <span class="hlt">heterogeneous</span> natural <span class="hlt">system</span>, Lake Mývatn, Iceland</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Millet, Antoine; Kristjánsson, Bjarni K; Einarsson, Árni; Räsänen, Katja</p> <p>2013-01-01</p> <p>Eco-evolutionary responses of natural populations to spatial environmental variation strongly depend on the relative strength of environmental differences/natural selection and dispersal/gene flow. In absence of geographic barriers, as often is the case in lake ecosystems, gene flow is expected to constrain adaptive divergence between environments – favoring phenotypic plasticity or high trait variability. However, if divergent natural selection is sufficiently strong, adaptive divergence can occur in face of gene flow. The extent of divergence is most often studied between two contrasting environments, whereas potential for multimodal divergence is little explored. We investigated phenotypic (body size, defensive structures, and feeding morphology) and genetic (microsatellites) structure in threespine stickleback (Gasterosteus aculeatus) across five habitat types and two basins (North and South) within the geologically young and highly <span class="hlt">heterogeneous</span> Lake Mývatn, North East Iceland. We found that (1) North basin stickleback were, on average, larger and had relatively longer spines than South basin stickleback, whereas (2) feeding morphology (gill raker number and gill raker gap width) differed among three of five habitat types, and (3) there was only subtle genetic differentiation across the lake. Overall, our results indicate predator and prey mediated phenotypic divergence across multiple habitats in the lake, in face of gene flow. PMID:24223263</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/27516938','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/27516938"><span id="translatedtitle">OmpA signal peptide leads to <span class="hlt">heterogenous</span> secretion of B. subtilis chitosanase enzyme from E. coli expression <span class="hlt">system</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Pechsrichuang, Phornsiri; Songsiriritthigul, Chomphunuch; Haltrich, Dietmar; Roytrakul, Sittiruk; Namvijtr, Peenida; Bonaparte, Napolean; Yamabhai, Montarop</p> <p>2016-01-01</p> <p>The production of secreted recombinant proteins from E. coli is pivotal to the biotechnological industry because it reduces the cost of downstream processing. Proteins destined for secretion contain an N-terminal signal peptide that is cleaved by secretion machinery in the plasma membrane. The resulting protein is released in an active mature form. In this study, Bacillus subtilis chitosanase (Csn) was used as a model protein to compare the effect of two signal peptides on the secretion of heterologous recombinant protein. The results showed that the E. coli secretion machinery could recognize both native bacillus and E. coli signal peptides. However, only the native bacillus signal peptide could generate the same N-terminal sequence as in the wild type bacteria. When the recombinant Csn constructs contained the E. coli OmpA signal peptide, the secreted enzymes were <span class="hlt">heterogeneous</span>, comprising a mixed population of secreted enzymes with different N-terminal sequences. Nevertheless, the E. coli OmpA signal peptide was found to be more efficient for high expression and secretion of bacillus Csn. These findings may be used to help engineer other recombinant proteins for secretory production in E. coli. PMID:27516938</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/2472707','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/2472707"><span id="translatedtitle">[Molecular <span class="hlt">heterogeneity</span> of proteoglycan aggregates of human hyalin cartilage in normal conditions and in <span class="hlt">systemic</span> bone dysplasia].</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Feshchenko, S P; Krasnopol'skaia, K D; Rebrin, I A; Rudakov, S S</p> <p>1989-01-01</p> <p>Components of proteoglycan aggregates of human hyalin cartilage were studied under conditions of normal state and in some forms of osteochondrodysplasia. Extraction of uronic acids and protein from the tissue, amount of fractions and electrophoretic mobility of proteoglycan monomers, rations protein/glycosaminoglycans, keratan sulfate/chondroitin sulfate, a level and type of sulfatation as well as molecular mass of chondroitin sulfate, amino acid composition of rod protein, <span class="hlt">heterogeneity</span> of binding proteins (concerning their isoelectric points and molecular masses) and immunoreactivity of protein moiety in proteoglycan aggregates were studied in rib cartilage, knee joint and ala ossis ilii. Structural parameters of proteoglycan aggregates proved to be dissimilar and depended on cartilage localization and age of the donors. Impairments in the rate of chondroitin sulfate sulfatation were detected in achondrogenesis of the II type and in diastrophic dysplasia; an extraction ability and amount of proteoglycan fractions, relative content of glycosaminoglycans and binding proteins were altered in some other forms of osteochondrodysplasias. Numerous biochemical markers of extracellular matrix deterioration were detected, which are typical for various morphofunctional alterations in hyalin cartilage--hyperproliferative reactions, tissue prematuration, persistence of the embryonal type of metabolism. PMID:2472707</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27516938','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27516938"><span id="translatedtitle">OmpA signal peptide leads to <span class="hlt">heterogenous</span> secretion of B. subtilis chitosanase enzyme from E. coli expression <span class="hlt">system</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Pechsrichuang, Phornsiri; Songsiriritthigul, Chomphunuch; Haltrich, Dietmar; Roytrakul, Sittiruk; Namvijtr, Peenida; Bonaparte, Napolean; Yamabhai, Montarop</p> <p>2016-01-01</p> <p>The production of secreted recombinant proteins from E. coli is pivotal to the biotechnological industry because it reduces the cost of downstream processing. Proteins destined for secretion contain an N-terminal signal peptide that is cleaved by secretion machinery in the plasma membrane. The resulting protein is released in an active mature form. In this study, Bacillus subtilis chitosanase (Csn) was used as a model protein to compare the effect of two signal peptides on the secretion of heterologous recombinant protein. The results showed that the E. coli secretion machinery could recognize both native bacillus and E. coli signal peptides. However, only the native bacillus signal peptide could generate the same N-terminal sequence as in the wild type bacteria. When the recombinant Csn constructs contained the E. coli OmpA signal peptide, the secreted enzymes were <span class="hlt">heterogeneous</span>, comprising a mixed population of secreted enzymes with different N-terminal sequences. Nevertheless, the E. coli OmpA signal peptide was found to be more efficient for high expression and secretion of bacillus Csn. These findings may be used to help engineer other recombinant proteins for secretory production in E. coli.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016JPCM...28O4012T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016JPCM...28O4012T"><span id="translatedtitle">Disordered hyperuniform <span class="hlt">heterogeneous</span> materials</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Torquato, Salvatore</p> <p>2016-10-01</p> <p>Disordered hyperuniform many-body <span class="hlt">systems</span> are distinguishable states of matter that lie between a crystal and liquid: they are like perfect crystals in the way they suppress large-scale density fluctuations and yet are like liquids or glasses in that they are statistically isotropic with no Bragg peaks. These <span class="hlt">systems</span> play a vital role in a number of fundamental and applied problems: glass formation, jamming, rigidity, photonic and electronic band structure, localization of waves and excitations, self-organization, fluid dynamics, quantum <span class="hlt">systems</span>, and pure mathematics. Much of what we know theoretically about disordered hyperuniform states of matter involves many-particle <span class="hlt">systems</span>. In this paper, we derive new rigorous criteria that disordered hyperuniform two-phase <span class="hlt">heterogeneous</span> materials must obey and explore their consequences. Two-phase <span class="hlt">heterogeneous</span> media are ubiquitous; examples include composites and porous media, biological media, foams, polymer blends, granular media, cellular solids, and colloids. We begin by obtaining some results that apply to hyperuniform two-phase media in which one phase is a sphere packing in d-dimensional Euclidean space {{{R}}d} . Among other results, we rigorously establish the requirements for packings of spheres of different sizes to be ‘multihyperuniform’. We then consider hyperuniformity for general two-phase media in {{{R}}d} . Here we apply realizability conditions for an autocovariance function and its associated spectral density of a two-phase medium, and then incorporate hyperuniformity as a constraint in order to derive new conditions. We show that some functional forms can immediately be eliminated from consideration and identify other forms that are allowable. Specific examples and counterexamples are described. Contact is made with well-known microstructural models (e.g. overlapping spheres and checkerboards) as well as irregular phase-separation and Turing-type patterns. We also ascertain a family of</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/27545746','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/27545746"><span id="translatedtitle">Disordered hyperuniform <span class="hlt">heterogeneous</span> materials.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Torquato, Salvatore</p> <p>2016-10-19</p> <p>Disordered hyperuniform many-body <span class="hlt">systems</span> are distinguishable states of matter that lie between a crystal and liquid: they are like perfect crystals in the way they suppress large-scale density fluctuations and yet are like liquids or glasses in that they are statistically isotropic with no Bragg peaks. These <span class="hlt">systems</span> play a vital role in a number of fundamental and applied problems: glass formation, jamming, rigidity, photonic and electronic band structure, localization of waves and excitations, self-organization, fluid dynamics, quantum <span class="hlt">systems</span>, and pure mathematics. Much of what we know theoretically about disordered hyperuniform states of matter involves many-particle <span class="hlt">systems</span>. In this paper, we derive new rigorous criteria that disordered hyperuniform two-phase <span class="hlt">heterogeneous</span> materials must obey and explore their consequences. Two-phase <span class="hlt">heterogeneous</span> media are ubiquitous; examples include composites and porous media, biological media, foams, polymer blends, granular media, cellular solids, and colloids. We begin by obtaining some results that apply to hyperuniform two-phase media in which one phase is a sphere packing in d-dimensional Euclidean space [Formula: see text]. Among other results, we rigorously establish the requirements for packings of spheres of different sizes to be 'multihyperuniform'. We then consider hyperuniformity for general two-phase media in [Formula: see text]. Here we apply realizability conditions for an autocovariance function and its associated spectral density of a two-phase medium, and then incorporate hyperuniformity as a constraint in order to derive new conditions. We show that some functional forms can immediately be eliminated from consideration and identify other forms that are allowable. Specific examples and counterexamples are described. Contact is made with well-known microstructural models (e.g. overlapping spheres and checkerboards) as well as irregular phase-separation and Turing-type patterns. We also ascertain a family</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009ACPD....9.3945S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009ACPD....9.3945S"><span id="translatedtitle">The <span class="hlt">heterogeneous</span> reaction of hydroxyl radicals with sub-micron squalane particles: a model <span class="hlt">system</span> for understanding the oxidative aging of ambient aerosols</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Smith, J. D.; Kroll, J. H.; Cappa, C. D.; Che, D. L.; Liu, C. L.; Ahmed, M.; Leone, S. R.; Worsnop, D. R.; Wilson, K. R.</p> <p>2009-02-01</p> <p>The <span class="hlt">heterogeneous</span> reaction of OH radicals with sub-micron squalane particles, in the presence of O2, is used as a model <span class="hlt">system</span> to explore the fundamental chemical mechanisms that control the oxidative aging of organic aerosols in the atmosphere. Detailed kinetic measurements combined with elemental mass spectrometric analysis reveal that the reaction proceeds sequentially by adding an average of one oxygenated functional group per reactive loss of squalane. The reactive uptake coefficient of OH with squalane particles is determined to be 0.3±0.07 at an average OH concentration of ~1×1010 molecules·cm-3. Based on a comparison between the measured particle mass and model predictions it appears that significant volatilization of a reduced organic particle would be extremely slow in the real atmosphere. However, as the aerosols become more oxygenated, volatilization becomes a significant loss channel for organic material in the particle phase. Together these results provide a chemical framework in which to understand how <span class="hlt">heterogeneous</span> chemistry transforms the physiochemical properties of particle phase organic matter in the troposphere.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009ACP.....9.3209S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009ACP.....9.3209S"><span id="translatedtitle">The <span class="hlt">heterogeneous</span> reaction of hydroxyl radicals with sub-micron squalane particles: a model <span class="hlt">system</span> for understanding the oxidative aging of ambient aerosols</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Smith, J. D.; Kroll, J. H.; Cappa, C. D.; Che, D. L.; Liu, C. L.; Ahmed, M.; Leone, S. R.; Worsnop, D. R.; Wilson, K. R.</p> <p>2009-05-01</p> <p>The <span class="hlt">heterogeneous</span> reaction of OH radicals with sub-micron squalane particles, in the presence of O2, is used as a model <span class="hlt">system</span> to explore the fundamental chemical mechanisms that control the oxidative aging of organic aerosols in the atmosphere. Detailed kinetic measurements combined with elemental mass spectrometric analysis reveal that the reaction proceeds sequentially by adding an average of one oxygenated functional group per reactive loss of squalane. The reactive uptake coefficient of OH with squalane particles is determined to be 0.3±0.07 at an average OH concentration of ~1×1010 molecules cm-3. Based on a comparison between the measured particle mass and model predictions it appears that significant volatilization of a reduced organic particle would be extremely slow in the real atmosphere. However, as the aerosols become more oxygenated, volatilization becomes a significant loss channel for organic material in the particle-phase. Together these results provide a chemical framework in which to understand how <span class="hlt">heterogeneous</span> chemistry transforms the physiochemical properties of particle-phase organic matter in the troposphere.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1995SPIE.2609..228D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1995SPIE.2609..228D"><span id="translatedtitle"><span class="hlt">Heterogeneous</span> broadband network</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Dittmann, Lars</p> <p>1995-11-01</p> <p>Although the vision for the future Integrated Broadband Communication Network (IBCN) is an all optical network, it is certain that for a long period to come, the network will remain very <span class="hlt">heterogeneous</span>, with a mixture of different physical media (fiber, coax and twisted pair), transmission <span class="hlt">systems</span> (PDH, SDH, ADSL) and transport protocols (TCP/IP, AAL/ATM, frame relay). In the current work towards the IBCN, the ATM concept is considered the generic network protocol for both public and private network, with the ability to use different underlying transmission protocols and, through adaptation protocols, provide the appropriate services (old as well as new) to the customer. One of the major difficulties of <span class="hlt">heterogeneous</span> network is the restriction that is usually given by the lowest common denominator, e.g. in terms of single channel capacity. A possible way to overcome these limitations is by extending the ATM concept with a multilink capability, that allows us to use separate resources as one common. The improved flexibility obtained by this protocol extension further allows a real time optimization of network and call configuration, without any impact on the quality of service seen from the user. This paper describes an example of an ATM based multilink protocol that has been experimentally implemented within the RACE project 'STRATOSPHERIC'. The paper outlines the complexity of introducing an extra network functionality compared with the added value, such as an improved ability to recover an error due to a malfunctioning network component.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26305227','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26305227"><span id="translatedtitle"><span class="hlt">Systems</span> Genetics Reveals the Functional Context of PCOS Loci and Identifies Genetic and Molecular Mechanisms of Disease <span class="hlt">Heterogeneity</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Jones, Michelle R; Brower, Meredith A; Xu, Ning; Cui, Jinrui; Mengesha, Emebet; Chen, Yii-Der I; Taylor, Kent D; Azziz, Ricardo; Goodarzi, Mark O</p> <p>2015-08-01</p> <p>Genome wide association studies (GWAS) have revealed 11 independent risk loci for polycystic ovary syndrome (PCOS), a common disorder in young women characterized by androgen excess and oligomenorrhea. To put these risk loci and the single nucleotide polymorphisms (SNPs) therein into functional context, we measured DNA methylation and gene expression in subcutaneous adipose tissue biopsies to identify PCOS-specific alterations. Two genes from the LHCGR region, STON1-GTF2A1L and LHCGR, were overexpressed in PCOS. In analysis stratified by obesity, LHCGR was overexpressed only in non-obese PCOS women. Although not differentially expressed in the entire PCOS group, INSR was underexpressed in obese PCOS subjects only. Alterations in gene expression in the LHCGR, RAB5B and INSR regions suggest that SNPs in these loci may be functional and could affect gene expression directly or indirectly via epigenetic alterations. We identified reduced methylation in the LHCGR locus and increased methylation in the INSR locus, changes that are concordant with the altered gene expression profiles. Complex patterns of meQTL and eQTL were identified in these loci, suggesting that local genetic variation plays an important role in gene regulation. We propose that non-obese PCOS women possess significant alterations in LH receptor expression, which drives excess androgen secretion from the ovary. Alternatively, obese women with PCOS possess alterations in insulin receptor expression, with underexpression in metabolic tissues and overexpression in the ovary, resulting in peripheral insulin resistance and excess ovarian androgen production. These studies provide a genetic and molecular basis for the reported clinical <span class="hlt">heterogeneity</span> of PCOS.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://eric.ed.gov/?q=income+AND+inequality&pg=7&id=EJ829777','ERIC'); return false;" href="http://eric.ed.gov/?q=income+AND+inequality&pg=7&id=EJ829777"><span id="translatedtitle">Social Capital and Community <span class="hlt">Heterogeneity</span></span></a></p> <p><a target="_blank" href="http://www.eric.ed.gov/ERICWebPortal/search/extended.jsp?_pageLabel=advanced">ERIC Educational Resources Information Center</a></p> <p>Coffe, Hilde</p> <p>2009-01-01</p> <p>Recent findings indicate that more pronounced community <span class="hlt">heterogeneity</span> is associated with lower levels of social capital. These studies, however, concentrate on specific aspects in which people differ (such as income inequality or ethnic diversity). In the present paper, we introduce the number of parties in the local party <span class="hlt">system</span> as a more…</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/25905484','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/25905484"><span id="translatedtitle"><span class="hlt">Heterogeneity</span> of European DRG <span class="hlt">systems</span> and potentials for a common EuroDRG <span class="hlt">system</span> Comment on "Cholecystectomy and Diagnosis-Related Groups (DRGs): patient classification and hospital reimbursement in 11 European countries".</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Geissler, Alexander; Quentin, Wilm; Busse, Reinhard</p> <p>2015-05-01</p> <p>Diagnosis-Related Group (DRG) <span class="hlt">systems</span> across Europe are very <span class="hlt">heterogeneous</span>, in particular because of different classification variables and algorithms as well as costing methodologies. But, given the challenge of increasing patient mobility within Europe, health <span class="hlt">systems</span> are forced to incorporate a common patient classification language in order to compare and identify similar patients e.g. for reimbursement purposes. Beside the national adoption of DRGs for a wide range of purposes (measuring hospital activity vs. paying hospitals), a common DRG <span class="hlt">system</span> can serve as an international communication basis among health administrators and can reduce the national development efforts as it is demonstrated by the NordDRG consortium. PMID:25905484</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25905484','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25905484"><span id="translatedtitle"><span class="hlt">Heterogeneity</span> of European DRG <span class="hlt">systems</span> and potentials for a common EuroDRG <span class="hlt">system</span> Comment on "Cholecystectomy and Diagnosis-Related Groups (DRGs): patient classification and hospital reimbursement in 11 European countries".</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Geissler, Alexander; Quentin, Wilm; Busse, Reinhard</p> <p>2015-03-05</p> <p>Diagnosis-Related Group (DRG) <span class="hlt">systems</span> across Europe are very <span class="hlt">heterogeneous</span>, in particular because of different classification variables and algorithms as well as costing methodologies. But, given the challenge of increasing patient mobility within Europe, health <span class="hlt">systems</span> are forced to incorporate a common patient classification language in order to compare and identify similar patients e.g. for reimbursement purposes. Beside the national adoption of DRGs for a wide range of purposes (measuring hospital activity vs. paying hospitals), a common DRG <span class="hlt">system</span> can serve as an international communication basis among health administrators and can reduce the national development efforts as it is demonstrated by the NordDRG consortium.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3903715','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3903715"><span id="translatedtitle">Single cell <span class="hlt">heterogeneity</span></span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Abdallah, Batoul Y; Horne, Steven D; Stevens, Joshua B; Liu, Guo; Ying, Andrew Y; Vanderhyden, Barbara; Krawetz, Stephen A; Gorelick, Root; Heng, Henry HQ</p> <p>2013-01-01</p> <p>Multi-level <span class="hlt">heterogeneity</span> is a fundamental but underappreciated feature of cancer. Most technical and analytical methods either completely ignore <span class="hlt">heterogeneity</span> or do not fully account for it, as <span class="hlt">heterogeneity</span> has been considered noise that needs to be eliminated. We have used single-cell and population-based assays to describe an instability-mediated mechanism where genome <span class="hlt">heterogeneity</span> drastically affects cell growth and cannot be accurately measured using conventional averages. First, we show that most unstable cancer cell populations exhibit high levels of karyotype <span class="hlt">heterogeneity</span>, where it is difficult, if not impossible, to karyotypically clone cells. Second, by comparing stable and unstable cell populations, we show that instability-mediated karyotype <span class="hlt">heterogeneity</span> leads to growth <span class="hlt">heterogeneity</span>, where outliers dominantly contribute to population growth and exhibit shorter cell cycles. Predictability of population growth is more difficult for <span class="hlt">heterogeneous</span> cell populations than for homogenous cell populations. Since “outliers” play an important role in cancer evolution, where genome instability is the key feature, averaging methods used to characterize cell populations are misleading. Variances quantify <span class="hlt">heterogeneity</span>; means (averages) smooth <span class="hlt">heterogeneity</span>, invariably hiding it. Cell populations of pathological conditions with high genome instability, like cancer, behave differently than karyotypically homogeneous cell populations. Single-cell analysis is thus needed when cells are not genomically identical. Despite increased attention given to single-cell variation mediated <span class="hlt">heterogeneity</span> of cancer cells, continued use of average-based methods is not only inaccurate but deceptive, as the “average” cancer cell clearly does not exist. Genome-level <span class="hlt">heterogeneity</span> also may explain population <span class="hlt">heterogeneity</span>, drug resistance, and cancer evolution. PMID:24091732</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/19924970','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/19924970"><span id="translatedtitle">Mechanism investigation of visible light-induced degradation in a <span class="hlt">heterogeneous</span> TiO2/eosin Y/rhodamine B <span class="hlt">system</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Yin, Mingcai; Li, Zhaosheng; Kou, Jiahui; Zou, Zhigang</p> <p>2009-11-01</p> <p>Visible light-induced degradation of rhodamine B (RhB) and eosin Y (EO) in a <span class="hlt">heterogeneous</span> TiO(2) P-25/EO/RhB <span class="hlt">system</span> was investigated in the present work. The results showed that the photodegradation of RhB is enhanced significantly when EO is introduced into the P-25/RhB <span class="hlt">system</span>. Under optimal conditions (50 mg P-25, 20 mg L(-1) EO), RhB (4 mg L(-1)) almost decomposed completely after 35 min of visible light irradiation, though EO was photodegraded simultaneously. The possible photodegradation mechanism was studied by the examination of active species HO*, O(2)(*-) anions, or dye radical cations through adding their scavengers such as methanol, t-butanol, benzoquinone, EDTA, and the I(-) anion. In addition, the electron paramagnetic resonance (EPR) spin trapping technique was also used to monitor the active oxygen species formed in the photocatalytic process. Combined with the contrastive experiments under different atmospheres (N(2)-purged or air) and in different <span class="hlt">systems</span>, it can be deduced that dissolved O(2) plays a crucial role in dye photodegradation and the O(2)(*-) anion is possibly the major active oxygen species. The low degradation rate with the introduction of EDTA or I(-) indicated that dye radical cations also play a part in photodegradation. Furthermore, except for the dye-sensitized photodegradation on the P-25 surface, reaction in bulk solution also occurs in this <span class="hlt">system</span>, leading to effective photodegradation of RhB.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2014PhRvE..89c0702P&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2014PhRvE..89c0702P&link_type=ABSTRACT"><span id="translatedtitle">Phenotypically <span class="hlt">heterogeneous</span> populations in spatially <span class="hlt">heterogeneous</span> environments</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Patra, Pintu; Klumpp, Stefan</p> <p>2014-03-01</p> <p>The spatial expansion of a population in a nonuniform environment may benefit from phenotypic <span class="hlt">heterogeneity</span> with interconverting subpopulations using different survival strategies. We analyze the crossing of an antibiotic-containing environment by a bacterial population consisting of rapidly growing normal cells and slow-growing, but antibiotic-tolerant persister cells. The dynamics of crossing is characterized by mean first arrival times and is found to be surprisingly complex. It displays three distinct regimes with different scaling behavior that can be understood based on an analytical approximation. Our results suggest that a phenotypically <span class="hlt">heterogeneous</span> population has a fitness advantage in nonuniform environments and can spread more rapidly than a homogeneous population.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014EJASP2014...77M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014EJASP2014...77M"><span id="translatedtitle">An orthogonal wavelet division multiple-access processor architecture for LTE-advanced wireless/radio-over-fiber <span class="hlt">systems</span> over <span class="hlt">heterogeneous</span> networks</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Mahapatra, Chinmaya; Leung, Victor CM; Stouraitis, Thanos</p> <p>2014-12-01</p> <p>The increase in internet traffic, number of users, and availability of mobile devices poses a challenge to wireless technologies. In long-term evolution (LTE) advanced <span class="hlt">system</span>, <span class="hlt">heterogeneous</span> networks (HetNet) using centralized coordinated multipoint (CoMP) transmitting radio over optical fibers (LTE A-ROF) have provided a feasible way of satisfying user demands. In this paper, an orthogonal wavelet division multiple-access (OWDMA) processor architecture is proposed, which is shown to be better suited to LTE advanced <span class="hlt">systems</span> as compared to orthogonal frequency division multiple access (OFDMA) as in LTE <span class="hlt">systems</span> 3GPP rel.8 (3GPP, http://www.3gpp.org/DynaReport/36300.htm). ROF <span class="hlt">systems</span> are a viable alternative to satisfy large data demands; hence, the performance in ROF <span class="hlt">systems</span> is also evaluated. To validate the architecture, the circuit is designed and synthesized on a Xilinx vertex-6 field-programmable gate array (FPGA). The synthesis results show that the circuit performs with a clock period as short as 7.036 ns (i.e., a maximum clock frequency of 142.13 MHz) for transform size of 512. A pipelined version of the architecture reduces the power consumption by approximately 89%. We compare our architecture with similar available architectures for resource utilization and timing and provide performance comparison with OFDMA <span class="hlt">systems</span> for various quality metrics of communication <span class="hlt">systems</span>. The OWDMA architecture is found to perform better than OFDMA for bit error rate (BER) performance versus signal-to-noise ratio (SNR) in wireless channel as well as ROF media. It also gives higher throughput and mitigates the bad effect of peak-to-average-power ratio (PAPR).</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li class="active"><span>23</span></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_23 --> <div id="page_24" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li class="active"><span>24</span></li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="461"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26387320','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26387320"><span id="translatedtitle">[Degradation of 3,4- Dichlorobenzotrifluoride by Fe3O4/CeO2-H2O2 <span class="hlt">Heterogeneous</span> Fenton-Like <span class="hlt">Systems</span>].</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Sun, Zheng-nan; Yang, Qi; Ji, Dong-li; Zheng, Lin</p> <p>2015-06-01</p> <p>The 3,4-Dichlorobenzotrifluoride (3,4-DCBTE) was dehalogenated with oxidation treatment by <span class="hlt">heterogeneous</span> Fenton-like <span class="hlt">system</span>, using nanoscale Fe304/CeO2 as a catalyst. This nanoscale catalyst was prepared by the impregnated method. As a highly active new <span class="hlt">heterogeneous</span> Fenton-like catalyst, nanoscale Fe304/CeO2 not only has the characteristics of the traditional Fenton-like catalyst but also can prevent the secondary pollution which caused by Fe2+. To find the optimum catalytic conditions for nanoscale Fe3O4/CeO2, the influence factors were investigated. The results indicated that the degradation ratio of 3,4-DCBTE was significantly improved by adding nanoscale Fe3O4/CeO2, with the removal ratio reaching 97.76% in 120 minutes and 79.85% in 20 minutes. As the temperature increasing, the catalytic effect of nanoscale Fe3O4/CeO2 catalyst had been constantly improved obviously. As the pH decreased, the degradation ratio of 3,4-DCBTE increased. With the increase of dosage of hydrogen peroxide (H2O2), the degradation efficiency of 3,4-DCBTE initially increased and then decreased, because oxygen (O2) was generated in preferential self-reaction when an excess of (H2O2) was added. The optimum removal efficiency was observed with the dosage of 15 mg x L(-1). With the increased amount of catalyst, there was a same trend as dosage of hydrogen peroxide (H2O2). The degradation ratio of 3,4-DCBTE initially increased and then decreased, the optimum amount of catalyst was 0.5 g x L(-1). The results also suggested that the reaction process followed the first-order kinetics and the thermodynamic analysis demonstrated that the reaction was only needed low reaction activation energy.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4756593','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4756593"><span id="translatedtitle">Patterns of Emphysema <span class="hlt">Heterogeneity</span></span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Valipour, Arschang; Shah, Pallav L.; Gesierich, Wolfgang; Eberhardt, Ralf; Snell, Greg; Strange, Charlie; Barry, Robert; Gupta, Avina; Henne, Erik; Bandyopadhyay, Sourish; Raffy, Philippe; Yin, Youbing; Tschirren, Juerg; Herth, Felix J.F.</p> <p>2016-01-01</p> <p>Background Although lobar patterns of emphysema <span class="hlt">heterogeneity</span> are indicative of optimal target sites for lung volume reduction (LVR) strategies, the presence of segmental, or sublobar, <span class="hlt">heterogeneity</span> is often underappreciated. Objective The aim of this study was to understand lobar and segmental patterns of emphysema <span class="hlt">heterogeneity</span>, which may more precisely indicate optimal target sites for LVR procedures. Methods Patterns of emphysema <span class="hlt">heterogeneity</span> were evaluated in a representative cohort of 150 severe (GOLD stage III/IV) chronic obstructive pulmonary disease (COPD) patients from the COPDGene study. High-resolution computerized tomography analysis software was used to measure tissue destruction throughout the lungs to compute <span class="hlt">heterogeneity</span> (≥ 15% difference in tissue destruction) between (inter-) and within (intra-) lobes for each patient. Emphysema tissue destruction was characterized segmentally to define patterns of <span class="hlt">heterogeneity</span>. Results Segmental tissue destruction revealed interlobar <span class="hlt">heterogeneity</span> in the left lung (57%) and right lung (52%). Intralobar <span class="hlt">heterogeneity</span> was observed in at least one lobe of all patients. No patient presented true homogeneity at a segmental level. There was true homogeneity across both lungs in 3% of the cohort when defining <span class="hlt">heterogeneity</span> as ≥ 30% difference in tissue destruction. Conclusion Many LVR technologies for treatment of emphysema have focused on interlobar <span class="hlt">heterogeneity</span> and target an entire lobe per procedure. Our observations suggest that a high proportion of patients with emphysema are affected by interlobar as well as intralobar <span class="hlt">heterogeneity</span>. These findings prompt the need for a segmental approach to LVR in the majority of patients to treat only the most diseased segments and preserve healthier ones. PMID:26430783</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014PhRvX...4c1037J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014PhRvX...4c1037J"><span id="translatedtitle">Free-Propagator Reweighting Integrator for Single-Particle Dynamics in Reaction-Diffusion Models of <span class="hlt">Heterogeneous</span> Protein-Protein Interaction <span class="hlt">Systems</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Johnson, Margaret E.; Hummer, Gerhard</p> <p>2014-07-01</p> <p>We present a new algorithm for simulating reaction-diffusion equations at single-particle resolution. Our algorithm is designed to be both accurate and simple to implement, and to be applicable to large and <span class="hlt">heterogeneous</span> <span class="hlt">systems</span>, including those arising in <span class="hlt">systems</span> biology applications. We combine the use of the exact Green's function for a pair of reacting particles with the approximate free-diffusion propagator for position updates to particles. Trajectory reweighting in our free-propagator reweighting (FPR) method recovers the exact association rates for a pair of interacting particles at all times. FPR simulations of many-body <span class="hlt">systems</span> accurately reproduce the theoretically known dynamic behavior for a variety of different reaction types. FPR does not suffer from the loss of efficiency common to other path-reweighting schemes, first, because corrections apply only in the immediate vicinity of reacting particles and, second, because by construction the average weight factor equals one upon leaving this reaction zone. FPR applications include the modeling of pathways and networks of protein-driven processes where reaction rates can vary widely and thousands of proteins may participate in the formation of large assemblies. With a limited amount of bookkeeping necessary to ensure proper association rates for each reactant pair, FPR can account for changes to reaction rates or diffusion constants as a result of reaction events. Importantly, FPR can also be extended to physical descriptions of protein interactions with long-range forces, as we demonstrate here for Coulombic interactions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFMIN53D1587L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFMIN53D1587L"><span id="translatedtitle">A Standard-Driven Data Dictionary for Data Harmonization of <span class="hlt">Heterogeneous</span> Datasets in Urban Geological Information <span class="hlt">Systems</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Liu, G.; Wu, C.; Li, X.; Song, P.</p> <p>2013-12-01</p> <p>The 3D urban geological information <span class="hlt">system</span> has been a major part of the national urban geological survey project of China Geological Survey in recent years. Large amount of multi-source and multi-subject data are to be stored in the urban geological databases. There are various models and vocabularies drafted and applied by industrial companies in urban geological data. The issues such as duplicate and ambiguous definition of terms and different coding structure increase the difficulty of information sharing and data integration. To solve this problem, we proposed a national standard-driven information classification and coding method to effectively store and integrate urban geological data, and we applied the data dictionary technology to achieve structural and standard data storage. The overall purpose of this work is to set up a common data platform to provide information sharing service. Research progresses are as follows: (1) A unified classification and coding method for multi-source data based on national standards. Underlying national standards include GB 9649-88 for geology and GB/T 13923-2006 for geography. Current industrial models are compared with national standards to build a mapping table. The attributes of various urban geological data entity models are reduced to several categories according to their application phases and domains. Then a logical data model is set up as a standard format to design data file structures for a relational database. (2) A multi-level data dictionary for data standardization constraint. Three levels of data dictionary are designed: model data dictionary is used to manage <span class="hlt">system</span> database files and enhance maintenance of the whole database <span class="hlt">system</span>; attribute dictionary organizes fields used in database tables; term and code dictionary is applied to provide a standard for urban information <span class="hlt">system</span> by adopting appropriate classification and coding methods; comprehensive data dictionary manages <span class="hlt">system</span> operation and security. (3</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/18940933','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/18940933"><span id="translatedtitle">Accounting for sap flow from different parts of the root <span class="hlt">system</span> improves the prediction of xylem ABA concentration in plants grown with <span class="hlt">heterogeneous</span> soil moisture.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Dodd, Ian C; Egea, Gregorio; Davies, William J</p> <p>2008-01-01</p> <p>When soil moisture is <span class="hlt">heterogeneous</span>, sap flow from, and ABA status of, different parts of the root <span class="hlt">system</span> impact on leaf xylem ABA concentration ([X-ABA]leaf). The robustness of a model for predicting [X-ABA]leaf was assessed. 'Two root-one shoot' grafted sunflower (Helianthus annuus L.) plants received either deficit irrigation (DI, each root <span class="hlt">system</span> received the same irrigation volumes) or partial rootzone drying (PRD, only one root <span class="hlt">system</span> was watered and the other dried the soil). Irrespective of whether relative sap flow was assessed using sap flow sensors in vivo or by pressurization of de-topped roots, each root <span class="hlt">system</span> contributed similarly to total sap flow during DI, while sap flow from roots in drying soil declined linearly with soil water potential (Psisoil) during PRD. Although Psisoil of the irrigated pot determined the threshold Psisoil at which sap flow from roots in drying soil decreased, the slope of this decrease was independent of the wet pot Psisoil. Irrespective of whether sap was collected from the wet or dry root <span class="hlt">system</span> of PRD plants, or a DI plant, root xylem ABA concentration increased as Psisoil declined. The model, which weighted ABA contributions of each root <span class="hlt">system</span> according to the sap flow from each, almost perfectly explained [X-ABA] immediately above the graft union. That the model overestimated measured [X-ABA]leaf may result from changes in [X-ABA] along the transport pathway or an artefact of collecting xylem sap from detached leaves. The implications of declining sap flow through partially dry roots during PRD for the control of stomatal behaviour and irrigation scheduling are discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2639021','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2639021"><span id="translatedtitle">Accounting for sap flow from different parts of the root <span class="hlt">system</span> improves the prediction of xylem ABA concentration in plants grown with <span class="hlt">heterogeneous</span> soil moisture</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Dodd, Ian C.; Egea, Gregorio; Davies, William J.</p> <p>2008-01-01</p> <p>When soil moisture is <span class="hlt">heterogeneous</span>, sap flow from, and ABA status of, different parts of the root <span class="hlt">system</span> impact on leaf xylem ABA concentration ([X-ABA]leaf). The robustness of a model for predicting [X-ABA]leaf was assessed. ‘Two root-one shoot’ grafted sunflower (Helianthus annuus L.) plants received either deficit irrigation (DI, each root <span class="hlt">system</span> received the same irrigation volumes) or partial rootzone drying (PRD, only one root <span class="hlt">system</span> was watered and the other dried the soil). Irrespective of whether relative sap flow was assessed using sap flow sensors in vivo or by pressurization of de-topped roots, each root <span class="hlt">system</span> contributed similarly to total sap flow during DI, while sap flow from roots in drying soil declined linearly with soil water potential (Ψsoil) during PRD. Although Ψsoil of the irrigated pot determined the threshold Ψsoil at which sap flow from roots in drying soil decreased, the slope of this decrease was independent of the wet pot Ψsoil. Irrespective of whether sap was collected from the wet or dry root <span class="hlt">system</span> of PRD plants, or a DI plant, root xylem ABA concentration increased as Ψsoil declined. The model, which weighted ABA contributions of each root <span class="hlt">system</span> according to the sap flow from each, almost perfectly explained [X-ABA] immediately above the graft union. That the model overestimated measured [X-ABA]leaf may result from changes in [X-ABA] along the transport pathway or an artefact of collecting xylem sap from detached leaves. The implications of declining sap flow through partially dry roots during PRD for the control of stomatal behaviour and irrigation scheduling are discussed. PMID:18940933</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4776671','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4776671"><span id="translatedtitle">Tumour Cell <span class="hlt">Heterogeneity</span></span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Gay, Laura; Baker, Ann-Marie; Graham, Trevor A.</p> <p>2016-01-01</p> <p>The population of cells that make up a cancer are manifestly <span class="hlt">heterogeneous</span> at the genetic, epigenetic, and phenotypic levels. In this mini-review, we summarise the extent of intra-tumour <span class="hlt">heterogeneity</span> (ITH) across human malignancies, review the mechanisms that are responsible for generating and maintaining ITH, and discuss the ramifications and opportunities that ITH presents for cancer prognostication and treatment. PMID:26973786</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2536202','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2536202"><span id="translatedtitle"><span class="hlt">Heterogeneities</span> of the malaria vectorial <span class="hlt">system</span> in tropical Africa and their significance in malaria epidemiology and control</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Coluzzi, Mario</p> <p>1984-01-01</p> <p>The most important units of the malaria vectorial <span class="hlt">system</span> in tropical Africa are included in the Linnaean taxon Anopheles gambiae, which has been split into six sibling species recognized by the application of genetic techniques. More recent studies have shown further complexities involving chromosomal inversion polymorphism in some vector populations as well as incipient speciation processes. The significance for field research in malaria of the splitting of a morphological taxon into genetically defined units and subunits is discussed. PMID:6335681</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/18992989','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/18992989"><span id="translatedtitle">Rapid decolorization and mineralization of simulated textile wastewater in a <span class="hlt">heterogeneous</span> Fenton like <span class="hlt">system</span> with/without external energy.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Zhou, Tao; Lu, Xiaohua; Wang, Jia; Wong, Fook-Sin; Li, Yaozhong</p> <p>2009-06-15</p> <p>A novel Fenton like <span class="hlt">system</span>, employing Zero Valent Iron (ZVI) and air bubbling, was developed to treat a simulated textile wastewater containing azo dye Reactive Black 5 (RB5) and Ethylenediaminetetraacetic acid (EDTA). By dioxygen activation, H(2)O(2) was self-produced continuously in the <span class="hlt">system</span> through a series of iron-EDTA ligands reactions. After 3h reaction, the removal rates of RB5, EDTA, Total Organic Carbon (TOC), and Chemical Oxygen Demand (COD) were 100%, 96.5%, 68.6% and 92.2%, respectively. The effects of pH, atmosphere as well as the initial concentration of RB5, EDTA and ZVI were also investigated. Two types of external energy-Ultrasound (US) and Ultraviolet (UV) were introduced into the Fenton like <span class="hlt">system</span>, respectively. The effect of these external energies on the degradation of the wastewater was assessed. It was demonstrated that US presented significant synergistic effect on the degradation and mineralization of both RB5 and EDTA, while UV could not achieve any improvement.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014ApSS..319..358V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014ApSS..319..358V"><span id="translatedtitle">Modified Fe3O4- hydroxyapatite nanocomposites as <span class="hlt">heterogeneous</span> catalysts in three UV, Vis and Fenton like degradation <span class="hlt">systems</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Valizadeh, S.; Rasoulifard, M. H.; Dorraji, M. S. Seyed</p> <p>2014-11-01</p> <p>The magnetite-hydroxyapatite (M-HAP) nanocomposites were prepared by a chemical co- precipitation procedure and characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), scanning electron microscopy (SEM) and diffuse reflectance spectra (DRS). The ability of the synthesized catalyst for photocatalytic degradation of Acid Blue 25 (AB25), as an organic dye, under UV irradiation was studied. The catalyst was modified employing transition metals (Mn, Fe, Co, Ni, Cu and Zn) trying to improve the catalytic performance of HAP in absence of UV irradiation and in the presence of hydrogen peroxide i.e. a Fenton like reaction. The best results obtained for Cu and Co modified M-HAPs and the effect of operational parameters such pH, amount of catalyst and hydrogen peroxide concentration was studied. In order to investigate the performance of HAP based photocatalyst in visible light region, M-HAP was modified with silver ions. At the end, Langmuir-Hinshelwood kinetic expression used to evaluate and compare the catalytic <span class="hlt">systems</span>. The strongest degradation activity was observed for Ag-M-HAP/Vis <span class="hlt">system</span> because of Ag3PO4 formation. Apparent reaction rate constant (Kapp) by Ag-M-HAP/Vis was 63, 36 and 19 times faster than Cu-M-HAP(II)/H2O2, Co-M-HAP(II)/H2O2 and M-HAP (I)/UV <span class="hlt">systems</span>, respectively.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70016881','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70016881"><span id="translatedtitle">Geochemistry of lavas from Taal volcano, southwestern Luzon, Philippines: evidence for multiple magma supply <span class="hlt">systems</span> and mantle source <span class="hlt">heterogeneity</span></span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Miklius, Asta; Flower, M.F.J.; Huijsmans, J.P.P.; Mukasa, S.B.; Castillo, P.</p> <p>1991-01-01</p> <p>Taal lava series can be distinguished from each other by differences in major and trace element trends and trace element ratios, indicating multiple magmatic <span class="hlt">systems</span> associated with discrete centers in time and space. On Volcano Island, contemporaneous lava series range from typically calc-alkaline to iron-enriched. Major and trace element variation in these series can be modelled by fractionation of similar assemblages, with early fractionation of titano-magnetite in less iron-enriched series. However, phase compositional and petrographic evidence of mineral-liquid disequilibrium suggests that magma mixing played an important role in the evolution of these series. -from Authors</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016SMaS...25f5015K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016SMaS...25f5015K"><span id="translatedtitle">Development and full-scale dynamic test of a combined <span class="hlt">system</span> of <span class="hlt">heterogeneous</span> laser sensors for structural displacement measurement</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kim, Kiyoung; Kim, Junhee; Sohn, Hoon</p> <p>2016-06-01</p> <p>The displacement responses of civil structures reveal the overall state of the structures and consist of two distinctive dynamic behaviors: pseudo-static deflection and structural vibration. In this study, a dynamic displacement estimation <span class="hlt">system</span> is developed by integrating a laser Doppler vibrometer (LDV) and terrestrial laser scanner (TLS). The TLS displacement data contaminated with high noise and measured with a low sampling rate is converted to high sampling rate dynamic displacements including the pseudo-static motion by fusing with the velocity data measured by the LDV which are at a high sampling rate but miss the pseudo-static components.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/812157','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/812157"><span id="translatedtitle">Harness: <span class="hlt">Heterogeneous</span> Adaptable Reconfigurable Networked <span class="hlt">Systems</span> -- U.S. Department of Energy Grant DE-FG02-99ER25379 Final Project Report</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Vaidy Sunderam</p> <p>2003-07-02</p> <p>Issues in reconfigurability and adaptability in <span class="hlt">heterogeneous</span> distributed <span class="hlt">systems</span> for high-performance computing are the focus of the work funded by this grant. Our efforts are part of an ongoing research project in metacomputing and are a follow on to the DOE funded PVM <span class="hlt">system</span> that has witnessed over a decade of use at numerous institutions worldwide. The current project, termed Harness, investigates novel methodologies and tools for distributed metacomputing, focusing on dynamically reconfigurable software frameworks. During the first phase, we defined the metacomputing architecture embodied in Harness and developed prototype subsystems as proof of concept exercises. Subsequently, we designed and developed a complete software framework manifesting the Harness architecture, and also developed several tools and subsystems that demonstrated the viability and effectiveness of our proposed model for next generation metacomputing. We then used this substrate to emulate multiple programming environments on Harness, and conducted performance evaluation and tuning exercises. The main research results from these efforts include the establishment of software metacomputing <span class="hlt">systems</span> as viable and cost-effective alternatives to MPPs; the demonstration of dynamic and reconfigurable platforms as effective methods of tailoring parallel computing environments; the development of methodologies to construct plugin modules for component-based distributed <span class="hlt">systems</span>; contributions to performance modeling and optimization in emulated software environments; and software architectures for multi- and mixed-paradigm parallel distributed computing. Details and specifics on these and other results have been reported in numerous publications, and are manifested in software <span class="hlt">systems</span>, all of which may be accessed at or via the website http://www.mathcs.emory.edu/harness/</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4937195','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4937195"><span id="translatedtitle">MOLGENIS/connect: a <span class="hlt">system</span> for semi-automatic integration of <span class="hlt">heterogeneous</span> phenotype data with applications in biobanks</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Pang, Chao; van Enckevort, David; de Haan, Mark; Kelpin, Fleur; Jetten, Jonathan; Hendriksen, Dennis; de Boer, Tommy; Charbon, Bart; Winder, Erwin; van der Velde, K. Joeri; Doiron, Dany; Fortier, Isabel; Hillege, Hans</p> <p>2016-01-01</p> <p>Motivation: While the size and number of biobanks, patient registries and other data collections are increasing, biomedical researchers still often need to pool data for statistical power, a task that requires time-intensive retrospective integration. Results: To address this challenge, we developed MOLGENIS/connect, a semi-automatic <span class="hlt">system</span> to find, match and pool data from different sources. The <span class="hlt">system</span> shortlists relevant source attributes from thousands of candidates using ontology-based query expansion to overcome variations in terminology. Then it generates algorithms that transform source attributes to a common target DataSchema. These include unit conversion, categorical value matching and complex conversion patterns (e.g. calculation of BMI). In comparison to human-experts, MOLGENIS/connect was able to auto-generate 27% of the algorithms perfectly, with an additional 46% needing only minor editing, representing a reduction in the human effort and expertise needed to pool data. Availability and Implementation: Source code, binaries and documentation are available as open-source under LGPLv3 from http://github.com/molgenis/molgenis and www.molgenis.org/connect. Contact: m.a.swertz@rug.nl Supplementary information: Supplementary data are available at Bioinformatics online. PMID:27153686</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015TePhL..41..930P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015TePhL..41..930P"><span id="translatedtitle">The thermovoltaic effect in zinc oxide inhomogeneously doped with <span class="hlt">mixed-valence</span> impurities</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Pronin, I. A.; Averin, I. A.; Bozhinov, A. S.; Georgieva, A. Ts.; Dimitrov, D. Ts.; Karmanov, A. A.; Moshnikov, V. A.; Papazova, K. I.; Terukov, E. I.; Yakushova, N. D.</p> <p>2015-10-01</p> <p>The thermovoltaic effect has been for the first time observed in zinc oxide. The samples had the form of ZnO/ZnO-Me sandwich structures (Me = Cu, Fe) formed by the sol-gel method. An electromotive force of 1-10 mV appeared in the temperature range of 200-300°C.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/20815362','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/20815362"><span id="translatedtitle"><span class="hlt">Mixed-valence</span> dinitrogen-bridged Fe(0)/Fe(II) complex.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Field, Leslie D; Guest, Ruth W; Turner, Peter</p> <p>2010-10-01</p> <p>The reactions of a dinitrogen-bridged Fe(II)/Fe(II) complex [(FeH(PP(3)))(2)(μ-N(2))](2+) (3) (PP(3) = P(CH(2)CH(2)PMe(2))(3)) with base were investigated using (15)N labeling techniques to enhance characterization. In the presence of base, 3 is initially deprotonated to the Fe(II)/Fe(0) dinitrogen-bridged complex [(FeH(PP(3)))(μ-N(2))(Fe(PP(3)))](+) (4) and then to the symmetrical Fe(0)/Fe(0) dinitrogen-bridged complex (Fe(PP(3)))(2)(μ-N(2)) (5). [(FeH(PP(3)))(μ-N(2))(Fe(PP(3)))](+) (4) exhibits unusual long-range (31)P-(31)P NMR coupling through the bridging dinitrogen ligand from the phosphines at the Fe(0) center and those at the Fe(II) center. Reaction of 4 with base under an atmosphere of argon resulted in the known dinitrogen Fe(0) complex Fe(N(2))(PP(3)) (6) and a solvent C-H activation product. Complexes 3, 4, and 5 were fully characterized by multinuclear NMR spectroscopy, and complexes 3 and 4 by X-ray crystallography.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3406866','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3406866"><span id="translatedtitle">Mechanically induced intramolecular electron transfer in a <span class="hlt">mixed-valence</span> molecular shuttle</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Barnes, Jonathan C.; Fahrenbach, Albert C.; Dyar, Scott M.; Frasconi, Marco; Giesener, Marc A.; Zhu, Zhixue; Liu, Zhichang; Hartlieb, Karel J.; Carmieli, Ranaan; Wasielewski, Michael R.; Stoddart, J. Fraser</p> <p>2012-01-01</p> <p>The kinetics and thermodynamics of intramolecular electron transfer (IET) can be subjected to redox control in a bistable [2]rotaxane comprised of a dumbbell component containing an electron-rich 1,5-dioxynaphthalene (DNP) unit and an electron-poor phenylene-bridged bipyridinium (P-BIPY2+) unit and a cyclobis (paraquat-p-phenylene) (CBPQT4+) ring component. The [2]rotaxane exists in the ground-state co-conformation (GSCC) wherein the CBPQT4+ ring encircles the DNP unit. Reduction of the CBPQT4+ leads to the CBPQT2(•+) diradical dication while the P-BIPY2+ unit is reduced to its P-BIPY•+ radical cation. A radical-state co-conformation (RSCC) results from movement of the CBPQT2(•+) ring along the dumbbell to surround the P-BIPY•+ unit. This shuttling event induces IET to occur between the pyridinium redox centers of the P-BIPY•+ unit, a property which is absent between these redox centers in the free dumbbell and in the 1∶1 complex formed between the CBPQT2(•+) ring and the radical cation of methyl-phenylene-viologen (MPV•+). Using electron paramagnetic resonance (EPR) spectroscopy, the process of IET was investigated by monitoring the line broadening at varying temperatures and determining the rate constant (kET = 1.33 × 107 s-1) and activation energy (ΔG‡ = 1.01 kcal mol-1) for electron transfer. These values were compared to the corresponding values predicted, using the optical absorption spectra and Marcus–Hush theory. PMID:22685213</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://eric.ed.gov/?q=Css&pg=2&id=EJ975236','ERIC'); return false;" href="http://eric.ed.gov/?q=Css&pg=2&id=EJ975236"><span id="translatedtitle">One but Not the Same: Evaluative Conditioning with <span class="hlt">Mixed-Valence</span> USs</span></a></p> <p><a target="_blank" href="http://www.eric.ed.gov/ERICWebPortal/search/extended.jsp?_pageLabel=advanced">ERIC Educational Resources Information Center</a></p> <p>Glaser, Tina; Walther, Eva</p> <p>2012-01-01</p> <p>In evaluative conditioning (EC), the pairing of a positively or negatively valenced stimulus (US) with another neutral stimulus (CS) leads to a corresponding change in liking of the CS. EC research so far has concentrated on using unambiguously positive or negative USs. However, attitude objects often possess multiple features that can be positive…</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/27409068','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/27409068"><span id="translatedtitle">A Dinitrogen Dicopper(I) Complex via a <span class="hlt">Mixed-Valence</span> Dicopper Hydride.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Zhang, Shiyu; Fallah, Hengameh; Gardner, Evan J; Kundu, Subrata; Bertke, Jeffery A; Cundari, Thomas R; Warren, Timothy H</p> <p>2016-08-16</p> <p>Low-temperature reaction of the tris(pyrazolyl)borate copper(II) hydroxide [(iPr2) TpCu]2 (μ-OH)2 with triphenylsilane under a dinitrogen atmosphere gives the bridging dinitrogen complex [(iPr2) TpCu]2 (μ-1,2-N2 ) (3). X-ray crystallography reveals an only slightly activated N2 ligand (N-N: 1.111(6) Å) that bridges between two monovalent (iPr2) TpCu fragments. While DFT studies of mono- and dinuclear copper dinitrogen complexes suggest weak π-backbonding between the d(10) Cu(I) centers and the N2 ligand, they reveal a degree of cooperativity in the dinuclear Cu-N2 -Cu interaction. Addition of MeCN, CNAr(2,6-Me) , or O2 to 3 releases N2 with formation of (iPr2) TpCu(L) (L=NCMe, CNAr(2,6-Me2) ) or [(iPr2) TpCu]2 (μ-η(2) :η(2) -O2 ) (1). Addition of triphenylsilane to [(iPr2) TpCu]2 (μ-OH)2 in pentane allows isolation of a key intermediate [(iPr2) TpCu]2 (μ-H) (5). Although 5 thermally decays under N2 to give 3, it reduces unsaturated substrates, such as CO and HC≡CPh to HC(O)H and H2 C=CHPh, respectively. PMID:27409068</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/1913458','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/1913458"><span id="translatedtitle"><span class="hlt">Heterogeneity</span> in the gingival fibromatoses.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Takagi, M; Yamamoto, H; Mega, H; Hsieh, K J; Shioda, S; Enomoto, S</p> <p>1991-11-15</p> <p>Forty-nine cases of isolated familial and idiopathic gingival fibromatoses, consisting of 12 cases from six families and 37 cases of idiopathic gingival fibromatosis, were reviewed. Pedigrees of five families revealed various penetrances and genetic <span class="hlt">heterogeneity</span> as suggested by the presence of both autosomal dominant and autosomal recessive inheritances. Ultrastructurally, the lesions were composed of fibroblast-like cells and myofibroblast-like cells, with the former being the predominant cell type. The 267 cases of familial and idiopathic gingival fibromatoses were analyzed, and they with or without hypertrichosis, mental retardation, and/or epilepsy. These included 49 cases seen by the authors, 50 cases from the Japanese literature, and 168 cases from non-Japanese literature. Isolated gingival fibromatosis occurred more frequently after age of 12 years (P less than 0.0074). There was no significant difference in age of onset between generalized and localized forms of the idiopathic gingival fibromatosis. Gingival fibromatosis with hypertrichosis and mental retardation and/or epilepsy occurred frequently before 12 years (P less than 0.069). It has been shown that <span class="hlt">heterogeneity</span> of the gingival fibromatosis is a result of either histologic <span class="hlt">heterogeneity</span>, genetic <span class="hlt">heterogeneity</span>, or a combination with other <span class="hlt">systemic</span> disorders.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li class="active"><span>24</span></li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_24 --> <div id="page_25" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li class="active"><span>25</span></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="481"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70034129','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70034129"><span id="translatedtitle">Geochemical <span class="hlt">heterogeneity</span> in a small, stratigraphically complex moraine aquifer <span class="hlt">system</span> (Ontario, Canada): Interpretation of flow and recharge using multiple geochemical parameters</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Stotler, R.L.; Frape, S.K.; El Mugammar, H.T.; Johnston, C.; Judd-Henrey, I.; Harvey, F.E.; Drimmie, R.; Jones, J.P.</p> <p>2011-01-01</p> <p>The Waterloo Moraine is a stratigraphically complex <span class="hlt">system</span> and is the major water supply to the cities of Kitchener and Waterloo in Ontario, Canada. Despite over 30 years of investigation, no attempt has been made to unify existing geochemical data into a single database. A composite view of the moraine geochemistry has been created using the available geochemical information, and a framework created for geochemical data synthesis of other similar flow <span class="hlt">systems</span>. Regionally, fluid chemistry is highly <span class="hlt">heterogeneous</span>, with large variations in both water type and total dissolved solids content. Locally, upper aquifer units are affected by nitrate and chloride from fertilizer and road salt. Typical upper-aquifer fluid chemistry is dominated by calcium, magnesium, and bicarbonate, a result of calcite and dolomite dissolution. Evidence also suggests that ion exchange and diffusion from tills and bedrock units accounts for some elevated sodium concentrations. Locally, hydraulic "windows" cross connect upper and lower aquifer units, which are typically separated by a clay till. Lower aquifer units are also affected by dedolomitization, mixing with bedrock water, and locally, upward diffusion of solutes from the bedrock aquifers. A map of areas where aquifer units are geochemically similar was constructed to highlight areas with potential hydraulic windows. ?? 2010 Springer-Verlag.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016GeCoA.186...13S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016GeCoA.186...13S"><span id="translatedtitle">Spatial <span class="hlt">heterogeneity</span> of sources of branched tetraethers in shelf <span class="hlt">systems</span>: The geochemistry of tetraethers in the Berau River delta (Kalimantan, Indonesia)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sinninghe Damsté, Jaap S.</p> <p>2016-08-01</p> <p>The bulk organic matter composition (total organic carbon (TOC) content and δ13CTOC) and composition of isoprenoid and branched glycerol dialkyl glycerol tetraethers (GDGT) in surface sediments from 43 stations in the Berau River delta (east Kalimantan, Indonesia), including two coast-shelf transects and stations within the river mouth, were examined to reveal the spatial <span class="hlt">heterogeneity</span> in these parameters in order to assess the impact of a tropical river loaded with suspended matter on the sedimentary organic matter in the shelf <span class="hlt">system</span>. The high-resolution study showed that, despite the extensive transport of eroded soil material by the river to the sea, terrestrial organic matter and brGDGTs are only deposited on a relatively small part of the shelf. The concentrations of brGDGTs are highest (up to 120 μg g-1 TOC) in sediments deposited in and close to the mouth of the Berau River and their distribution indicates that they represent a mixture of soil-derived and river in-situ produced brGDGTs. Crenarchaeol concentrations reach 700 μg g-1 TOC in sediments deposited on the outer shelf due to Thaumarchaeotal production in shelf waters. This results in a strong gradient (0.93-0.03) in the BIT index, with high values in the river mouth and low values on the shelf. The decline in the BIT index is caused by both decreasing concentrations of the brGDGTs and increasing concentrations of crenarchaeol. The BIT index shows a highly significant but non-linear relationship with δ13CTOC. On the shelf, in the area not under the direct influence of the Berau River, cyclic brGDGTs become relatively dominant, most probably due to in-situ production in the alkaline pore waters of the surface sediments. The spatial <span class="hlt">heterogeneity</span> of sources of brGDGTs on the Berau shelf complicates the use of brGDGTs as temperature proxies. Application of the global soil calibration to sedimentary mixtures of brGDGTs in the river-influenced area of the shelf results in a severe underestimation of</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19930017974','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19930017974"><span id="translatedtitle"><span class="hlt">Heterogeneous</span> photocatalytic oxidation of atmospheric trace contaminants</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Ollis, David F.</p> <p>1993-01-01</p> <p>Work performed during the period 1 May - 31 Oct. 1992 on <span class="hlt">heterogeneous</span> photocatalytic oxidation of atmospheric trace contaminants is presented. Topics discussed include photoreactor monolith fundamental studies and monolith reactor operation: batch recirculation <span class="hlt">system</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010LNCS.6152...36C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010LNCS.6152...36C"><span id="translatedtitle">InterDataNet Naming <span class="hlt">System</span>: A Scalable Architecture for Managing URIs of <span class="hlt">Heterogeneous</span> and Distributed Data with Rich Semantics</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Chini, Davide; Pirri, Franco; Pettenati, Maria Chiara; Innocenti, Samuele; Ciofi, Lucia</p> <p></p> <p>Establishing equivalence links between (semantic) resources, as it is the case in the Linked Data approach, implies permanent search, analysis and alignment of new (semantic) data in a rapidly changing environment. Moreover the distributed management of data brings not negligible requirements as regards their authorship, update, versioning and replica management. Instead of providing solutions for the above issues at the application level, our approach relies on the adoption of a common layered infrastructure: InterDataNet (IDN). The core of the IDN architecture is the Naming <span class="hlt">System</span> aimed at providing a scalable and open service to support consistent reuse of entities and their identifiers, enabling a global reference and addressing mechanism for convenient retrieval of resources. The IDN architecture also provides basic collaboration-oriented functions for (semantic) data, featuring authorship control, versioning and replica management through its stack layers.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/19132702','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/19132702"><span id="translatedtitle">Zr-zeolite beta: a new <span class="hlt">heterogeneous</span> catalyst <span class="hlt">system</span> for the highly selective cascade transformation of citral to (+/-)-menthol.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Nie, Yuntong; Jaenicke, Stephan; Chuah, Gaik-Khuan</p> <p>2009-01-01</p> <p>The transformation of citral to menthols involves hydrogenation steps as well as cyclisation of the intermediate, citronellal. The ability of Zr-zeolite beta to catalyse the cyclisation with high diastereoselectivity to (+/-)-isopulegol is the critical step in this cascade transformation. Bifunctional catalysts containing nickel or rhodium supported on Zr-zeolite beta gave menthols in yields of 87-89% and an excellent diastereoselectivity of 94% for the desired (+/-)-menthol. Dual catalyst <span class="hlt">systems</span> of Zr-zeolite beta and nano-dispersed Ni on an MCM-41 support were equally effective and have the added advantage that the rates of the acid- and hydrogenation-catalysed steps can be independently varied. By applying a pressure ramp of 0.2-2 MPa, the yield of menthols could be increased to 95%, with 94% diastereoselectivity for (+/-)-menthol. The low initial pressure minimises the rates of competing hydrogenation reactions to byproducts such as citronellol and 3,7-dimethyloctanol. PMID:19132702</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/21305041','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/21305041"><span id="translatedtitle">A <span class="hlt">HETEROGENEOUS</span> CHEMICAL ORIGIN FOR THE {sup 16}O-ENRICHED AND {sup 16}O-DEPLETED RESERVOIRS OF THE EARLY SOLAR <span class="hlt">SYSTEM</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Dominguez, Gerardo</p> <p>2010-04-10</p> <p>The oldest solids formed in the solar <span class="hlt">system</span>, calcium-aluminum inclusions, are {sup 16}O-enriched compared to chondrules, asteroids, Earth, and Mars. Based on the preliminary measurements of the solar wind by Genesis, the Sun also appears to be {sup 16}O-enriched. This distribution of oxygen isotopes in the solar <span class="hlt">system</span> cannot be reconciled via conventional mass-dependent isotopic fractionation processes and instead require the existence and/or production of distinct {sup 16}O-enriched and {sup 16}O-depleted reservoirs in the early solar <span class="hlt">system</span>. The origin of these distinct reservoirs is unknown, although several mechanisms have been proposed to date including the following: (1) the injection of pure {sup 16}O by a supernova into the protoplanetary disk or parent molecular cloud, (2) self-shielding of CO in the parent molecular cloud or protoplanetary disk, (3) symmetry-dependent chemical fractionation processes in the protoplanetary disk, and (4) Galactic chemical evolution. While some of these proposals have been ruled out, the validity of others is still open. Here I propose that the {sup 16}O-enriched and {sup 16}O-depleted reservoirs present in the early solar <span class="hlt">system</span> originated in the parent molecular cloud via the <span class="hlt">heterogeneous</span> chemical processes that form H{sub 2}O, a significant oxygen reservoir, on the surface of interstellar (IS) dust grains in dense molecular clouds, the astrophysical setting where star formation is observed to occur. As a consequence, this model predicts that molecular cloud H{sub 2}O and possibly other IS solids inherited from the molecular cloud were depleted in {sup 16}O compared to the bulk gas-phase O present, thus providing distinct {sup 16}O reservoirs at the earliest stages of planetary formation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/23428023','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/23428023"><span id="translatedtitle">Monoclonal antibody <span class="hlt">heterogeneity</span> analysis and deamidation monitoring with high-performance cation-exchange chromatofocusing using simple, two componen