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Sample records for heterogeneous mixed-valence system

  1. 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. Copyright © 2014 Wiley Periodicals, Inc.

  2. Intramolecular electronic couplings in class II/III organic mixed-valence systems of bis(1,4-dimethoxybenzene).

    PubMed

    Yang, Juanhua; Zhang, Weiwei; Si, Yubing; Zhao, Yi

    2012-12-06

    The intramolecular electronic couplings in organic mixed-valence systems [D-(ph)(n)-D](•+) (D = 2,5-dimethoxy-4-methylphenyl, n = 0, 1, and 2) are calculated by dominantly using density functional theory to investigate their dependence of functionals. Since these systems have the property that the charge is from localization to delocalization, the optimized structures are sensitive to the functionals. The geometric optimizations show that CAM-B3LYP and ωB97X-D functionals are good choices for delocalized systems and LC-ωPBE and M06HF are suitable for the systems from charge almost localization to localization. The calculations of electronic couplings demonstrate that the pure functional generally underestimates the electronic couplings whereas the pure HF overestimates them. Furthermore, the electronic couplings from the conventional generalized Mulliken-Hush method are very sensitive to the HF component in functionals, which makes it a challenge to accurately estimate the values. A new reduced two-state method is thus proposed to overcome the deficiency, and the obtained electronic couplings are less sensitive to the ω value in LC-ω PBE functional and they are also consistent with the experimental data.

  3. Introducing Students to Inner Sphere Electron Transfer Concepts through Electrochemistry Studies in Diferrocene Mixed-Valence Systems

    ERIC Educational Resources Information Center

    Ventura, Karen; Smith, Mark B.; Prat, Jacob R.; Echegoyen, Lourdes E.; Villagran´, Dino

    2017-01-01

    We have designed a 4 h physical chemistry laboratory to introduce upper division students to electrochemistry concepts, including mixed valency and electron transfer (ET), using cyclic and differential pulse voltammetries. In this laboratory practice, students use a ferrocene dimer consisting of two ferrocene centers covalently bonded through a…

  4. 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.

  5. 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.

  6. 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.

  7. Accuracy of embedded fragment calculation for evaluating electron interactions in mixed valence magnetic systems: study of 2e-reduced lindqvist polyoxometalates.

    PubMed

    Suaud, Nicolas; López, Xavier; Ben Amor, Nadia; Bandeira, Nuno A G; de Graaf, Coen; Poblet, Josep M

    2015-02-10

    Accurate quantum chemical calculations on real-world magnetic systems are challenging, the inclusion of electron correlation being the bottleneck of such task. One method proposed to overcome this difficulty is the embedded fragment approach. It tackles a chemical problem by dividing it into small fragments, which are treated in a highly accurate way, surrounded by an embedding included at an approximate level. For the vast family of medium-to-large sized polyoxometalates, two-electron-reduced systems are habitual and their magnetic properties are interesting. In this paper, we aim at assessing the quality of embedded fragment calculations by checking their ability to reproduce the electronic spectra of a complete system, here the mixed-metal series [MoxW6-xO19](4-) (x = 0-6). The microscopic parameters extracted from fragment calculations (electron hopping, intersite electrostatic repulsion, local orbital energy, etc.) have been used to reproduce the spectra through model Hamiltonian calculations. These energies are compared to the results of the highly accurate ab initio difference dedicated configuration interaction (DDCI) method on the complete system. In general, the model Hamiltonian calculations using parameters extracted from embedded fragments nearly exactly reproduce the DDCI spectra. This is quite an important result since it can be generalized to any inorganic magnetic system. Finally, the occurrence of singlet or triplet ground states in the series of molecules studied is rationalized upon the interplay of the parameters extracted.

  8. Density functional investigation of metal-metal interactions in mixed-valence d2d3 (Cr, Mo, W) and d3d4 (Mn, Tc, Re) face-shared [M2Cl9]2- systems.

    PubMed

    Cavigliasso, Germán; Comba, Peter; Stranger, Robert

    2004-10-18

    The molecular and electronic structures of mixed-valence face-shared (Cr, Mo, W) d(2)d(3) and (Mn, Tc, Re) d(3)d(4) [M(2)Cl(9)](2-) dimers have been calculated by density functional methods in order to investigate metal-metal bonding in this series. The electronic structures of these systems have been analyzed using potential energy curves for the broken-symmetry and other spin states arising from the d(2)d(3) and d(3)d(4) coupling modes. In (d(2)d(3)) [Mo(2)Cl(9)](2-) and [W(2)Cl(9)](2-), the global minimum has been found to be a spin-doublet state characterized by delocalization of the metal-based electrons in a multiple metal-metal bond (with a formal bond order of 2.5). In contrast, weak coupling between the metal centers and electron localization are favored in (d(2)d(3)) [Cr(2)Cl(9)](2-), the global minimum for this species being a ferromagnetic S = 5/2 state with a relatively long Cr-Cr separation. The (d(3)d(4)) [Re(2)Cl(9)](2-) system also exhibits a global minimum corresponding to a metal-metal bonded spin-doublet state with a formal bond order of 2.5, reflecting the electron-hole equivalence between d(2)d(3) and d(3)d(4) configurations. Double minima behavior is predicted for (d(3)d(4)) [Tc(2)Cl(9)](2-) and [Mn(2)Cl(9)](2-) due to two energetically close low-lying states (these being S = 3/2 and S = 5/2 states for the former, and S = 5/2 and S = 7/2 states for the latter). A comparison of computational results for the d(2)d(2), d(2)d(3), and d(3)d(3) [W(2)Cl(9)](z-) series and the d(3)d(3), d(3)d(4), and d(4)d(4) [Re(2)Cl(9)](z-) series indicates that the observed trends in metal-metal distances can only be rationalized if changes in both the strength of sigma bonding and metal-metal bond order are taken into consideration. These two factors act conjointly in the W series but in opposition to one another in the Re series. In the case of the [Cr(2)Cl(9)](z-) and [Mn(2)Cl(9)](z-) dimers, the metal-metal bond lengths are significantly shorter for mixed-valence

  9. 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.

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

    PubMed

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

    2016-07-07

    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.

  11. Static and dynamic magnetic response of the mixed-valence state: Cerium-based alloys

    SciTech Connect

    Grier, B.H.; Shapiro, S.M.; Majkrzak, C.F.; Parks, R.D.

    1980-08-25

    For the first time crystal-field excitations are observed in the inelastic-neutron-scattering spectra of a mixed-valence system, viz., Ce/sub 0.9-x/La/sub x/Th/sub 0.1/. Scaling relationships are established which connect various energy-related quantities, such as the T=0 Fermi-liquid susceptibility, the valence transition temperature, and the spin-fluctuation energy as measured by the neutron scattering linewidths.

  12. Self-doping of molecular quantum-dot cellular automata: mixed valence zwitterions.

    PubMed

    Lu, Yuhui; Lent, Craig

    2011-09-07

    Molecular quantum-dot cellular automata (QCA) is a promising paradigm for realizing molecular electronics. In molecular QCA, binary information is encoded in the distribution of intramolecular charge, and Coulomb interactions between neighboring molecules combine to create long-range correlations in charge distribution that can be exploited for signal transfer and computation. Appropriate mixed-valence species are promising candidates for single-molecule device operation. A complication arises because many mixed-valence compounds are ions and the associated counterions can potentially disrupt the correct flow of information through the circuit. We suggest a self-doping mechanism which incorporates the counterion covalently into the structure of a neutral molecular cell, thus producing a zwitterionic mixed-valence complex. The counterion is located at the geometrical center of the QCA molecule and bound to the working dots via covalent bonds, thus avoiding counterion effects that bias the system toward one binary information state or the other. We investigate the feasibility of using multiply charged anion (MCA) boron clusters, specifically closo-borate dianion, as building blocks. A first principle calculation shows that neutral, bistable, and switchable QCA molecules are possible. The self-doping mechanism is confirmed by molecular orbital analysis, which shows that MCA counterions can be stabilized by the electrostatic interaction between negatively charged counterions and positively charged working dots. This journal is © the Owner Societies 2011

  13. Configurational electronic entropy and the phase diagram of mixed-valence oxides: the case of LixFePO4.

    PubMed

    Zhou, Fei; Maxisch, Thomas; Ceder, Gerbrand

    2006-10-13

    We demonstrate that configurational electronic entropy, previously neglected, in ab initio thermodynamics of materials can qualitatively modify the finite-temperature phase stability of mixed-valence oxides. While transformations from low-T ordered or immiscible states are almost always driven by configurational disorder (i.e., random occupation of lattice sites by multiple species), in FePO4-LiFePO4 the formation of a solid solution is almost entirely driven by electronic rather than ionic configurational entropy. We argue that such an electronic entropic mechanism may be relevant to most other mixed-valence systems.

  14. Role of spin dependent f- d interaction (Hund coupling) in mixed-valence phenomena

    NASA Astrophysics Data System (ADS)

    Ghosh, N. K.; Mukherjee, P.

    2016-06-01

    The effect of spin dependent f- d interaction (Hund coupling) in mixed-valence phenomena has been investigated within Falicov-Kimball model extended by the spin interaction. Calculations have been performed both at zero and at finite temperatures using exact diagonalization method. It is observed that spin dependent f- d interaction (1) shifts the d-level energy and increases the width of valence transition, (2) increases disorder in the system, (3) causes both single peak and double peak structures to appear in specific heat curves, (4) increases the growth of antiferromagnetic correlations.

  15. Spectroscopic consequences of a mixed valence excited state: quantitative treatment of a dihydrazine diradical dication.

    PubMed

    Lockard, Jenny V; Zink, Jeffrey I; Konradsson, Asgeir E; Weaver, Michael N; Nelsen, Stephen F

    2003-11-05

    A model for the quantitative treatment of molecular systems possessing mixed valence excited states is introduced and used to explain observed spectroscopic consequences. The specific example studied in this paper is 1,4-bis(2-tert-butyl-2,3-diazabicyclo[2.2.2]oct-3-yl)-2,3,5,6-tetramethylbenzene-1,4-diyl dication. The lowest energy excited state of this molecule arises from a transition from the ground state where one positive charge is associated with each of the hydrazine units, to an excited state where both charges are associated with one of the hydrazine units, that is, a Hy-to-Hy charge transfer. The resulting excited state is a Class II mixed valence molecule. The electronic emission and absorption spectra, and resonance Raman spectra, of this molecule are reported. The lowest energy absorption band is asymmetric with a weak low-energy shoulder and an intense higher energy peak. Emission is observed at low temperature. The details of the absorption and emission spectra are calculated for the coupled surfaces by using the time-dependent theory of spectroscopy. The calculations are carried out in the diabatic basis, but the nuclear kinetic energy is explicitly included and the calculations are exact quantum calculations of the model Hamiltonian. Because the transition involves the transfer of an electron from the hydrazine on one side of the molecule to the hydrazine on the other side and vice versa, the two transitions are antiparallel and the transition dipole moments have opposite signs. Upon transformation to the adiabatic basis, the dipole moment for the transition to the highest energy adiabatic surface is nonzero, but that for the transition to the lowest surface changes sign at the origin. The energy separation between the two components of the absorption spectrum is twice the coupling between the diabatic basis states. The bandwidths of the electronic spectra are caused by progressions in totally symmetric modes as well as progressions in the modes

  16. 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

  17. Mixed-valence states of 11, 1111-dialkyl- and 11, 1111-bis(methylbenzyl)biferrocenium triiodides

    NASA Astrophysics Data System (ADS)

    Nakashima, Satoru; Masuda, Yuichi; Motoyama, Izumi; Sano, Hirotoshi

    1988-02-01

    It was found that the packing of cations and anions influences the electronic structures of mixed-valence binuclear ferrocene derivatives. Temperature-dependence of the mixed-valence state of 11, 1111-diisobutylbiferrocenium triiodide was observed in a crystalline state, whereas only a trapped-valence state was found in a dispersed state. The packing effect was also observed for a series of 11, 1111-dialkyl- and 11, 1111-bis(methylbenzyl)biferrocenium triiodides by means of ESR spectroscopy.

  18. 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.

  19. Tuning of quantum entanglement in molecular quantum cellular automata based on mixed-valence tetrameric units.

    PubMed

    Palii, Andrew; Tsukerblat, Boris

    2016-10-25

    In this article we consider two coupled tetrameric mixed-valence (MV) units accommodating electron pairs, which play the role of cells in molecular quantum cellular automata. It is supposed that the Coulombic interaction between instantly localized electrons within the cell markedly inhibits the transfer processes between the redox centers. Under this condition, as well as due to the vibronic localization of the electron pair, the cell can encode binary information, which is controlled by neighboring cells. We show that under certain conditions the two low-lying vibronic spin levels of the cell (ground and first excited states) can be regarded as originating from an effective spin-spin interaction. This is shown to depend on the internal parameters of the cell as well as on the induced polarization. Within this simplified two-level picture we evaluate the quantum entanglement in the system represented by the two electrons in the cell and show how the entanglement within the cell and concurrence can be controlled via polarization of the neighboring cells and temperature.

  20. 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

    2016-07-27

    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) 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.

  1. 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.

  2. Study on spin configuration in photoresponsive iron mixed-valence complexes by Mössbauer spectroscopy

    NASA Astrophysics Data System (ADS)

    Okazawa, A.; Yoshida, J.; Kida, N.; Kashima, I.; Murata, W.; Enomoto, M.; Kojima, N.

    2014-04-01

    We have investigated magnetic properties in a series of photoresponsive dithiooxalato (dto)-bridged iron mixed-valence complexes, (SP-R)[FeIIFeIII(dto)3] (SP-R = R-substituted pyridospiropyran cation; R = Me, Et, and Pr; abbreviated as 1 Me, 1 Et, and 1 Pr, respectively). As for our previous reports, 1 Me and 1 Et show two-step succeeding ferromagnetic transitions at T C = 25 & 8 K and 22 & 5 K, respectively. However, 1 Et has no hysteresis in the magnetic susceptibility, while 1 Me undergoes the charge transfer phase transition with thermal hysteresis around 75 K. To elucidate the two-step transitions of them, we measured 57Fe Mössbauer spectra of 1 Et. The spectra of FeII ( S = 2) and FeIII ( S = 1/2) in the HTP were observed in the magnetically ordered state as well as the paramagnetic state, and revealed that only HTP exists in a temperature range up to 5 K. The result is consistent with that of 1 Pr, where one ferromagnetic phase transition occurs at T C = 10 K. 57Fe Mössbauer spectroscopy is useful to clarify the origin of the succeeding magnetic transition for these systems.

  3. 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

  4. 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.; ...

    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

  5. 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

    2013-10-07

    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.

  6. 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.

  7. Neptunium(vi) chain and neptunium(vi/v) mixed valence cluster complexes.

    PubMed

    Cornet, Stéphanie M; Häller, L Jonas L; Sarsfield, Mark J; Collison, David; Helliwell, Madeleine; May, Iain; Kaltsoyannis, Nikolas

    2009-02-28

    The synthesis of [Np(VI)O(2)Cl(2)(thf)](n) offers the potential for more detailed exploration of neptunyl(vi) chemistry, while the synthesis of the mixed valence cluster complex [{Np(VI)O(2)Cl(2)}{Np(V)O(2)Cl(thf)(3)}(2)] allows molecular neptunyl(v) 'cation-cation' interactions to be probed.

  8. PT L 3 near edge structure of halogen-bridged mixed-valence pt complexes and pd-pt mixed-metal complexes

    NASA Astrophysics Data System (ADS)

    Tanino, H.; Oyanagi, H.; Yamashita, M.; Kobayashi, K.

    1985-03-01

    X-ray absorption near edge structure (XANES) of halogen-bridged mixed-valence Pt complexes and halogen-bridged Pd-Pt mixed-metal complexes have been measured using synchrotron radiation with a high energy resolution. In Pd-Pt mixed metal complexes, we demonstrate that the degree of the valence is estimated from the intensity of the white line at the Pt L 3 edge. In the mixed-valence complexes, the electron system is proved to be the Peierls insulator with a charge density wave of renormalized d electrons of Pt, where the total valence of Pt IV- and Pt 11 is conserved without excess electrons from ligands or anions.

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

    SciTech Connect

    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) 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.

  10. Epitaxial growth and electronic properties of mixed valence YbAl{sub 3} thin films

    SciTech Connect

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

    2016-07-21

    We report the growth of thin films of the mixed valence compound YbAl{sub 3} 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 f{sup 13} and f{sup 12} final states establishing that YbAl{sub 3} is a mixed valence compound and shows the presence of a Kondo Resonance peak near the Fermi-level.

  11. Interpretation of unusual absorption bandwidths and resonance Raman intensities in excited state mixed valence.

    PubMed

    Lockard, Jenny V; Valverde, Guadalupe; Neuhauser, Daniel; Zink, Jeffrey I; Luo, Yun; Weaver, Michael N; Nelsen, Stephen F

    2006-01-12

    Excited state mixed valence (ESMV) occurs in molecules in which the ground state has a symmetrical charge distribution but the excited state possesses two or more interchangeably equivalent sites that have different formal oxidation states. Although mixed valence excited states are relatively common in both organic and inorganic molecules, their properties have only recently been explored, primarily because their spectroscopic features are usually overlapped or obscured by other transitions in the molecule. The mixed valence excited state absorption bands of 2,3-di-p-anisyl-2,3-diazabicyclo[2.2.2]octane radical cation are well-separated from others in the absorption spectrum and are particularly well-suited for detailed analysis using the ESMV model. Excited state coupling splits the absorption band into two components. The lower energy component is broader and more intense than the higher energy component. The absorption bandwidths are caused by progressions in totally symmetric modes, and the difference in bandwidths is caused by the coordinate dependence of the excited state coupling. The Raman intensities obtained in resonance with the high and low energy components differ significantly from those expected based on the oscillator strengths of the bands. This unexpected observation is a result of the excited state coupling and is explained by both the averaging of the transition dipole moment orientation over all angles for the two types of spectroscopies and the coordinate-dependent coupling. The absorption spectrum is fit using a coupled two-state model in which both symmetric and asymmetric coordinates are included. The physical meaning of the observed resonance Raman intensity trends is discussed along with the origin of the coordinate-dependent coupling. The well-separated mixed valence excited state spectroscopic components enable detailed electronic and resonance Raman data to be obtained from which the model can be more fully developed and tested.

  12. Molecular tectonics: crystal engineering of mixed valence Fe(II)/Fe(III) solid solutions.

    PubMed

    Dechambenoit, Pierre; Ferlay, Sylvie; Kyritsakas, Nathalie; Hosseini, Mir Wais

    2010-02-14

    Based on isostructurality between crystals formed upon combining the dicationic tecton 2 with either M(3)Fe(III)(CN)(6) or M(4)Fe(II)(CN)(6) (M = Cs), a rare example of an H-bonded mixed valence Fe(ii)-Fe(iii) solid solution ((Cs(2)2(3)-[Fe(II)(CN)(6)](2))(0.83)(2(3)-[Fe(III)(CN)(6)](2))(0.17))) and curious necklace-like composite crystals were generated.

  13. 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.

  14. 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

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

    PubMed

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

    2015-09-08

    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 began studying the reactivity of a dinuclear Cu(I) amidinate complex. The reaction of [(2,6-Me2C6H3N)2C(H)]2Cu2, 1, with I2 in tetrahydrofuran (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 were characterized by UV-vis and electron paramagnetic resonance spectroscopies, and their molecular structure was determined by X-ray crystallography. Both di- and trinuclear mixed-valence intermediates were characterized for the reaction of compound 1 to compound 4, and the molecular structure of 4 was determined by X-ray crystallography. The electronic structure of each of these complexes was also investigated using density functional theory.

  16. 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.

  17. 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

  18. A New Synthetic Route for Mixed-Valence Compounds: Leaching Treatments of Hydrogen Molybdenum Bronze

    NASA Astrophysics Data System (ADS)

    Eda, Kazuo; Sukejima, Ai; Sotani, Noriyuki

    2001-06-01

    In order to explore the possibilities of a new synthetic route, based on selective extraction of the same atomic species with different valences, for mixed-valence compounds, leaching treatments of HxMoO3 with various x values with various kinds of solutions were investigated. Both oxidation-type (pseudooxidation) and reduction-type (pseudoreduction) products could be obtained by these simple treatments without oxidizing or reducing agents. Their formation mechanisms were elucidated from various investigations of solutions as well as solids. Moreover, novel hydrated hydrogen-alkali metal co-insertion compounds of layered molybdenum oxide with larger hydrogen contents were obtained by the treatments.

  19. Charge transfer and mixed-valence behavior in phtalocyanine-dimer cations.

    PubMed

    Monari, Antonio; Evangelisti, Stefano; Leininger, Thierry

    2010-09-28

    Phtalocyanine compounds deserved a considerable interest in recent times, particularly because of their possible use in the field of nanoelectronics. In particular, the charge mobility (of both electrons and holes) in phtalocyanine stacked arrangements has been recently extensively investigated. The present work focuses on the study of the hole-transfer mechanism between two phtalocyanine monomers. For an interdisk distance larger than 4.5 bohrs, the eclipsed dimer exhibits a mixed-valence behavior, with a saddle point transition state separating two equivalent minima. This behavior, however, is strongly dependent on the relative angle between the disks. In particular, the mixed-valence character of the compound is strongly enhanced for arrangements that are far from the eclipsed geometry. Moreover, for values of the angle close to π/8 and 3π/8, the ground and excited transition states have exactly the same energy, thus implying the presence of a conical intersection. These results can have deep implication in the charge transfer along phtalocyanine chains.

  20. Hydrothermally derived water-dispersible mixed valence copper-chitosan nanocomposite as exceptionally potent antimicrobial agent

    NASA Astrophysics Data System (ADS)

    Basumallick, Srijita; Rajasekaran, Parthiban; Tetard, Laurene; Santra, Swadeshmukul

    2014-10-01

    We report, for the first time, a one-step hydrothermal (HT) process to design and synthesize water-dispersible chitosan nanoparticles loaded with mixed valence copper. Interestingly, this HT copper-chitosan biocompatible composite exhibits exceptionally high antimicrobial properties. A comprehensive characterization of the composite indicates that the hydrothermal process results in the formation of monodispersed nanoparticles with average size of 40 ± 10 nm. FT-IR and Raman spectroscopic studies unveiled that the hydrolysis of the glycoside bonds as the origin of the depolymerization of chitosan. Furthermore, X-Ray Photoelectron Spectroscopy measurements confirmed the presence of mixed valence copper states in the composite, while UV-Vis and FT-IR studies revealed the chemical interaction of copper with the chitosan matrix. Hence, the extensive spectroscopic data provide strong evidence that the chitosan structure was rearranged to capture copper oxide nanoparticles. Finally, HT copper-chitosan composite showed a complete killing effect when tested against both Gram negative ( E. coli) and Gram positive ( S. aureus) bacteria at metallic copper concentration of 100 μg/ml (1.57 mM). At the same concentration, neither pure chitosan nor copper elicited such antimicrobial efficacy. Thus, we show that HT process significantly enhances the synergistic antimicrobial effect of chitosan and copper in addition to increasing the water dispersibility.

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

    NASA Astrophysics Data System (ADS)

    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 energies

  2. Interconnecting heterogeneous database management systems

    NASA Technical Reports Server (NTRS)

    Gligor, V. D.; Luckenbaugh, G. L.

    1984-01-01

    It is pointed out that there is still a great need for the development of improved communication between remote, heterogeneous database management systems (DBMS). Problems regarding the effective communication between distributed DBMSs are primarily related to significant differences between local data managers, local data models and representations, and local transaction managers. A system of interconnected DBMSs which exhibit such differences is called a network of distributed, heterogeneous DBMSs. In order to achieve effective interconnection of remote, heterogeneous DBMSs, the users must have uniform, integrated access to the different DBMs. The present investigation is mainly concerned with an analysis of the existing approaches to interconnecting heterogeneous DBMSs, taking into account four experimental DBMS projects.

  3. Excited-state mixed-valence distortions in a diisopropyl diphenyl hydrazine cation.

    PubMed

    Lockard, Jenny V; Zink, Jeffrey I; Luo, Yun; Weaver, Michael N; Konradsson, Asgeir E; Fowble, Joseph W; Nelsen, Stephen F

    2006-12-27

    Excited-state mixed valence (ESMV) occurs in the 1,2-diphenyl-1,2-diisopropyl hydrazine radical cation, a molecule in which the ground state has a symmetrical charge distribution localized primarily on the hydrazine, but the phenyl to hydrazine charge-transfer excited state has two interchangeably equivalent phenyl groups that have different formal oxidation states. Electronic absorption and resonance Raman spectra are presented. The neighboring orbital model is employed to interpret the absorption spectrum and coupling. Resonance Raman spectroscopy is used to determine the excited-state distortions. The frequencies of the enhanced modes from the resonance Raman spectra are used together with the time-dependent theory of spectroscopy to fit the two observed absorption bands that have resolved vibronic structure. The origins of the vibronic structure and relationships with the neighboring orbital model are discussed.

  4. AgO investigated by photoelectron spectroscopy: Evidence for mixed valence

    NASA Astrophysics Data System (ADS)

    Bielmann, M.; Schwaller, P.; Ruffieux, P.; Gröning, O.; Schlapbach, L.; Gröning, P.

    2002-06-01

    We present photoelectron spectroscopy investigations of in-situ prepared AgO. The sample was prepared by room temperature oxidation of Ag in an electron cyclotron resonance O2 plasma. In contrast to other measurements based on ex situ prepared AgO powder samples, our investigations show a distinct double peak structure of the O 1s signal with a remarkable chemical shift of 2.9 eV between the two O 1s components. These two components can not be motivated from a crystallographic point of view as the oxygen sites are all equivalent in the unit cell. We interpret this double peak structure as a characteristic feature of AgO and discuss it in terms of mixed valences.

  5. Mixed-valence state of a pyrazine-bridged dimer of oxocarboxylatotriruthenium complexes with a nitrosyl ligand.

    PubMed

    Ohtsu, Hiroyoshi; Fujiwara, Naoya; Yamaguchi, Tadashi

    2011-08-15

    Three new pyrazine-bridged dimers of oxoacetatotriruthenium with an NO ligand are synthesized. These complexes show two types of stable mixed-valence states. The ν(NO) stretches for five oxidation states were obtained, and the intramolecular electron-transfer rate within the mixed-valence state is evaluated from the IR spectral line-shape simulation based on Bloch-type analysis, which is the first application of this method to a spectator ligand of NO. © 2011 American Chemical Society

  6. Mixed-valence polyoxometalate clusters. I. Delocalization of electronic pairs in dodecanuclear heteropoly blues with keggin structure

    NASA Astrophysics Data System (ADS)

    Borrás-Almenar, J. J.; Clemente, J. M.; Coronado, E.; Tsukerblat, B. S.

    1995-06-01

    The problem of delocalization of a pair of electrons over dodecanuclear polyoxometalate clusters with the Keggin structure is considered with the aim of explaining the spin pairing in these multi-nuclear mixed-valence systems. A general approach that considers the Coulomb interactions between the two delocalized electrons, as well as the single and double electron transfer processes which can be operative in delocalization of the electronic pairs is developed. The new approach is based on the site-symmetry concept which makes possible a group theoretical classification for the delocalized states of electronic pairs. This procedure proves to be very efficient in the calculation of the transfer matrices which are expressed in terms of the Coulomb energy, and the single- and double-transfer parameters. The influence of these electronic parameters on the spectrum of the low-lying energy levels of the cluster is discussed, and the conditions giving rise to the stabilization of a singlet ground spin state for the electronic pair are elucidated.

  7. Mixed valence as a necessary criteria for quasi-two dimensional electron gas in oxide hetero-interfaces

    NASA Astrophysics Data System (ADS)

    Singh, Vijeta; Pulikkotil, J. J.

    2017-02-01

    The origin of quasi-two dimensional electron gas at the interface of polar-nonpolar oxide hetero-structure, such as LaAlO3/SrTiO3, is debated over electronic reconstruction and defects/disorder models. Common to these models is the partial valence transformation of substrate Ti ions from its equilibrium 4 + state to an itinerant 3 + state. Given that the Hf ions have a lower ionization potential than Ti due to the 4 f orbital screening, one would expect a hetero-interface conductivity in the polar-nonpolar LaAlO3/SrHfO3 system as well. However, our first principles calculations show the converse. Unlike the Ti3+ -Ti4+ valence transition which occur at a nominal energy cost, the barrier energy associated with its isoelectronic Hf3+ -Hf4+ counterpart is very high, hence suppressing the formation of quasi-two dimensional electron gas at LaAlO3/SrHfO3 hetero-interface. These calculations, therefore, emphasize on the propensity of mixed valence at the interface as a necessary condition for an oxide hetero-structure to exihibit quasi two-dimensional electron gas.

  8. Na 1.7Ti 6O 11: A new mixed-valence nonstoichiometric sodium titanate with a tunnel structure

    NASA Astrophysics Data System (ADS)

    Akimoto, Junji; Takei, Humihiko

    1990-03-01

    From the high-temperature reaction of sodium metal and titanium oxide, a new member ofTi 3+/Ti 4-mixed valence sodium titanates, Na 1.7Ti 6O 11, was prepared. It is black in color and crystallizes in the tetragonal system, space group P4 2/ mnmwith lattice constants a = 11.7456(10)Å, and c = 2.9866(8)Å, V = 412.03(12)Å 3, and Z = 2.The structure was determined from a single-crystal X-ray diffraction study and refined to values of the conventional Rfactors of R = 0.038and Rw = 0.025for 783 observed reflections. The basic units of the structure are built up from six edge-shared TiO 6 octahedra, and they are linked along the c-axis by sharing edges to form rutile-type chains, as in the case of CaFe 2O 4-type NaTi 2O 4 and Na 2Ti 4O 9. Sodium atoms are located in the tunnels with an occupancy factor of 0.84(1), and two types of Ti sites are randomly occupied by Ti 3+ and Ti 4+ cations.

  9. 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

    2016-03-07

    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.

  10. Electric Field Generation and Control of Bipartite Quantum Entanglement between Electronic Spins in Mixed Valence Polyoxovanadate [GeV14O40](8).

    PubMed

    Palii, Andrew; Aldoshin, Sergey; Tsukerblat, Boris; Borràs-Almenar, Juan José; Clemente-Juan, Juan Modesto; Cardona-Serra, Salvador; Coronado, Eugenio

    2017-08-21

    As part of the search for systems in which control of quantum entanglement can be achieved, here we consider the paramagnetic mixed valence polyoxometalate K2Na6[GeV14O40]·10H2O in which two electrons are delocalized over the 14 vanadium ions. Applying a homogeneous electric field can induce an antiferromagnetic coupling between the two delocalized electronic spins that behave independently in the absence of the field. On the basis of the proposed theoretical model, we show that the external field can be used to generate controllable quantum entanglement between the two electronic spins traveling over a vanadium network of mixed valence polyoxoanion [GeV14O40](8-). Within a simplified two-level picture of the energy pattern of the electronic pair based on the previous ab initio analysis, we evaluate the temperature and field dependencies of concurrence and thus indicate that the entanglement can be controlled via the temperature, magnitude, and orientation of the electric field with respect to molecular axes of [GeV14O40](8-).

  11. Synthesis of a mixed valence state Ce-MOF as an oxidase mimetic for the colorimetric detection of biothiols.

    PubMed

    Xiong, Yuhao; Chen, Siheng; Ye, Fanggui; Su, Lingjing; Zhang, Cong; Shen, Shufen; Zhao, Shulin

    2015-03-18

    We demonstrate a facile and rapid in situ partial oxidation synthetic strategy for the fabrication of a mixed valence state Ce-MOF (MVCM) which exhibits intrinsic oxidase-like activity. Furthermore, on the basis of the excellent catalytic activity of the MCVM, a colorimetric approach for the high-throughput detection of biothiols in serum samples was established.

  12. 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.

  13. Site-selective XANES and EXAFS. A demonstration with manganese mixtures and mixed-valence complexes

    SciTech Connect

    Grush, M.M.; Christou, G.; Hamaelaeinen, K.; Cramer, S.P. |

    1995-05-31

    This paper presents the first demonstration that chemical shifts in X-ray fluorescence energies can be used to obtain site-selective X-ray absorption spectra. X-ray absorption spectroscopy (XAS) has become a powerful tool for probing both geometric and electronic structure. Here site-selective XANES and EXAFS using high-resolution fluorescence detection are demonstrated for a physical mixture of MnF{sub 2} and BaMn{sub 8}O{sub 16}{center_dot}2H{sub 2}O and for a Mn{sup II}Mn{sup III}{sub 2} mixed-valence complex, Mn{sub 3}O(O{sub 2}CPh){sub 6}(py){sub 2}(H{sub 2}O). There are many cases where fluorescence lines change with chemical environment; hence this method of site-selective XAS should have broad applicability. The main obstacle at the moment is signal-to-noise, but with new high-brightness synchrotron radiation sources and a larger collection solid angle, site-selective XAS using high-resolution fluorescence detection should become a more common and valuable technique. 24 refs., 2 figs.

  14. Mixed valence character of anionic linear beryllium chains: a CAS-SCF and MR-CI study.

    PubMed

    Pastore, Mariachiara; Monari, Antonio; Evangelisti, Stefano; Leininger, Thierry

    2009-12-31

    A theoretical investigation on the mixed valence behavior, or bistability, of a series of anionic linear chains composed of beryllium atoms is presented. Calculations on Be(N)- (with N = 7, ..., 13) were performed at CAS-SCF and MR-CI levels by using an ANO basis set containing 6s4p3d2f contracted orbitals for each atom. Our results show a consistent gradual shift between different classes of mixed valence compounds as the number of beryllium atoms increases, from strong coupling (class III) toward valence-trapped (class II). Indeed, in the largest cases (N > 10), the anionic chains were found to become asymptotically closer to class I, where the coupling vanishes. The intramolecular electron-transfer parameters V(ab), E(barr), and E(opt) were calculated for each atomic chain. It is shown that the decrease of V(ab) with increasing N follows an exponential pattern.

  15. Inter-cluster distance dependence of electrical properties in single crystals of a mixed-valence polyoxometalate.

    PubMed

    Tsunashima, Ryo; Nakamura, Ippei; Oue, Rika; Koga, Seiya; Oki, Hirofumi; Noro, Shin-Ichiro; Nakamura, Takayoshi; Akutagawa, Tomoyuki

    2017-09-26

    The electrical conductivity of mixed-valence [MoMoO54(SO3)2](6-) tetraalkylammonium salts was investigated through dependence on the inter-cluster distance that is controlled by tetraethylammonium, tetrapropylammonium, and tetrabutylammonium cations. The crystallographic analysis of single crystals revealed that the inter-cluster distances are dependent on the chain length of the alkyl groups on the counter cations. In addition, the electrical conductivities of the single crystals were found to be dependent on both temperature and chain length. Mixed-valence polyoxometalate (POM) clusters are considered to be a molecular particle of Mo bronze by which highly ordered networks will be developed using single crystals, where POMs are rather small and have a well-organized structure compared to colloidal nanostructures.

  16. Crystallographic Studies on the Mechanisms of the Cluster Formation and the Higher Order Structure Evolution of Mixed-valence Polyoxometalates

    NASA Astrophysics Data System (ADS)

    Ozeki, Tomoji

    The advantages of the use of synchrotron radiation for single crystal X-ray diffraction experiments were exploited to obtain a deeper understanding of the chemistry of polyoxometalates through structural investigations. The pH dependence of the structures of {Mo154-x} mixed-valence oxomolybdate clusters were investigated by analyzing the structures of systematically prepared compounds containing wheel-shaped mixed-valence polyoxometalates with 138, 142, 148, 150, or 152 molybdenum atoms. Direct correlation was observed between the nuclearity of the clusters with the pH of the mother liquor. On the other hand, the geometries of extended structures do not show apparent correlation with the pH. They turned out to be determined by the structures of the constituent polyoxometalate. The pH of the mother liquor exerts influence on the extended structure through the structures of the constituent clusters. Such systematic preparation—structure determination study was enabled by the use of synchrotron radiation.

  17. Thermally and chemically stable mixed valence copper oxide cluster ions revealed by post heating.

    PubMed

    Morita, Keisuke; Sakuma, Kazuko; Miyajima, Ken; Mafuné, Fumitaka

    2013-10-10

    Copper oxide clusters, Cu(n)O(m)(+) (n = 5-12), were prepared in the gas phase by laser ablation of a copper metal rod in the presence of oxygen diluted in He as the carrier gas. The stoichiometry of the cluster ions was investigated using mass spectrometry. The number ratio of copper atoms and oxygen atoms in Cu(n)O(m)(+) was distributed from n:m = 1:1-3:2, which was not affected significantly by the concentration of oxygen in the carrier gas as long as it exceeded 2%. When the cluster ions were heated up to 573 K downstream of the cluster source (post heating), Cu(n)O(m)(+) (n:m ≈ 3:2) clusters were selectively and dominantly formed as a result of thermal dissociation. No further changes in the ratio were observed when the clusters were heated up to 623 K. From the stoichiometry, Cu(n)O(m)(+) is considered to comprise both Cu(I) and Cu(II). Hence, the mixed valence states are found to be thermally stable for the small clusters in the gas phase, but they are not stable in the bulk phase. In addition to the thermal stability, we observed reactivity of Cu(n)O(m)(+) with CO molecules. It was found that Cu12O8(+) hardly binds to CO and that Cu9O6(+) and Cu6O4(+) along with other clusters with n:m ≈ 3:2 bind to CO very weakly, whereas CO attaches strongly to oxygen-rich clusters with release of an oxygen molecule.

  18. Dioxygen activation and bond cleavage by mixed-valence cytochrome c oxidase

    PubMed Central

    Proshlyakov, Denis A.; Pressler, Michelle A.; Babcock, Gerald T.

    1998-01-01

    Elucidating the structures of intermediates in the reduction of O2 to water by cytochrome c oxidase is crucial to understanding both oxygen activation and proton pumping by the enzyme. In the work here, the reaction of O2 with the mixed-valence enzyme, in which only heme a3 and CuB in the binuclear center are reduced, has been followed by time-resolved resonance Raman spectroscopy. The results show that O=O bond cleavage occurs within the first 200 μs after reaction initiation; the presence of a uniquely stable Fe—O—O(H) peroxy species is not detected. The product of this rapid reaction is a heme a3 oxoferryl (FeIV=O) species, which requires that an electron donor in addition to heme a3 and CuB must be involved. The available evidence suggests that the additional donor is an amino acid side chain. Recent crystallographic data [Yoshikawa, S., Shinzawa-Itoh, K., Nakashima, R., Yaono, R., Yamashita, E., Inoue, N., Yao, M., Fei, M. J., Libeu, C. P., Mizushima, T., et al. Science, in press; Ostermeier, C., Harrenga, A., Ermler, U. & Michel, H. (1997) Proc. Natl. Acad. Sci. USA 94, 10547–10553] show that one of the CuB ligands, His240, is cross-linked to Tyr244 and that this cross-linked tyrosyl is ideally positioned to participate in dioxygen activation. We propose a mechanism for O—O bond cleavage that proceeds by concerted hydrogen atom transfer from the cross-linked His—Tyr species to produce the product oxoferryl species, CuB2+—OH−, and the tyrosyl radical. This mechanism provides molecular structures for two key intermediates that drive the proton pump in oxidase; moreover, it has clear analogies to the proposed O—O bond forming chemistry that occurs during O2 evolution in photosynthesis. PMID:9653133

  19. 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. Copyright © 2012 Elsevier B.V. All rights reserved.

  20. 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.

  1. Europium mixed-valence, long-range magnetic order, and dynamic magnetic response in EuCu2(SixGe1-x)2

    DOE PAGES

    Nemkovski, Krill S.; Kozlenko, D. P.; Alekseev, Pavel A.; ...

    2016-11-01

    In mixed-valence or heavy-fermion systems, the hybridization between local f orbitals and conduction band states can cause the suppression of long-range magnetic order, which competes with strong spin uctuations. Ce- and Yb-based systems have been found to exhibit fascinating physical properties (heavy-fermion superconductivity, non-Fermi-liquid states, etc.) when tuned to the vicinity of magnetic quantum critical points by use of various external control parameters (temperature, magnetic eld, chemical composition). Recently, similar effects (mixed-valence, Kondo uctuations, heavy Fermi liquid) have been reported to exist in some Eu-based compounds. Unlike Ce (Yb), Eu has a multiple electron (hole) occupancy of its 4f shell,more » and the magnetic Eu2+ state (4f7) has no orbital component in the usual LS coupling scheme, which can lead to a quite different and interesting physics. In the EuCu2(SixGe1-x)2 series, where the valence can be tuned by varying the Si/Ge ratio, it has been reported that a significant valence uctuation can exist even in the magnetic order regime. This paper presents a detailed study of the latter material using different microscopic probes (XANES, Mossbauer spectroscopy, elastic and inelastic neutron scattering), in which the composition dependence of the magnetic order and dynamics across the series is traced back to the change in the Eu valence state. In particular, the results support the persistence of valence uctuations into the antiferromagnetic state over a sizable composition range below the critical Si concentration xc ≈ 0:65. In conclusion, the sequence of magnetic ground states in the series is shown to re ect the evolution of the magnetic spectral response.« less

  2. Europium mixed-valence, long-range magnetic order, and dynamic magnetic response in EuCu2(SixGe1 -x)2

    NASA Astrophysics Data System (ADS)

    Nemkovski, K. S.; Kozlenko, D. P.; Alekseev, P. A.; Mignot, J.-M.; Menushenkov, A. P.; Yaroslavtsev, A. A.; Clementyev, E. S.; Ivanov, A. S.; Rols, S.; Klobes, B.; Hermann, R. P.; Gribanov, A. V.

    2016-11-01

    In mixed-valence or heavy-fermion systems, the hybridization between local f orbitals and conduction band states can cause the suppression of long-range magnetic order, which competes with strong spin fluctuations. Ce- and Yb-based systems have been found to exhibit fascinating physical properties (heavy-fermion superconductivity, non-Fermi-liquid states, etc.) when tuned to the vicinity of magnetic quantum critical points by use of various external control parameters (temperature, magnetic field, chemical composition). Recently, similar effects (mixed-valence, Kondo fluctuations, heavy Fermi liquid) have been reported to exist in some Eu-based compounds. Unlike Ce (Yb), Eu has a multiple electron (hole) occupancy of its 4 f shell, and the magnetic Eu2 + state (4 f7 ) has no orbital component in the usual L S coupling scheme, which can lead to a quite different and interesting physics. In the EuCu2(SixGe1 -x)2 series, where the valence can be tuned by varying the Si/Ge ratio, it has been reported that a significant valence fluctuation can exist even in the magnetic order regime. This paper presents a detailed study of the latter material using different microscopic probes (XANES, Mössbauer spectroscopy, elastic and inelastic neutron scattering), in which the composition dependence of the magnetic order and dynamics across the series is traced back to the change in the Eu valence state. In particular, the results support the persistence of valence fluctuations into the antiferromagnetic state over a sizable composition range below the critical Si concentration xc≈0.65 . The sequence of magnetic ground states in the series is shown to reflect the evolution of the magnetic spectral response.

  3. Crystal structures of two mixed-valence copper cyanide complexes with N-methyl-ethylenedi-amine.

    PubMed

    Corfield, Peter W R; Sabatino, Alexander

    2017-02-01

    The crystal structures of two mixed-valence copper cyanide compounds involving N-methyl-ethylenedi-amine (meen), are described. In compound (I), poly[bis(μ3-cyanido-κ3C:C:N)tris(μ2-cyanido-κ2C:N)bis(N-methylethane-1,2-di-amine-κ2N,N')tricopper(I)copper(II)], [Cu4(CN)5(C3H10N2)2] or Cu4(CN)5meen2, cyanide groups link Cu(I) atoms into a three-dimensional network containing open channels parallel to the b axis. In the network, two tetra-hedrally bound Cu(I) atoms are bonded by the C atoms of two end-on bridging CN groups to form Cu2(CN)6 moieties with the Cu atoms in close contact at 2.560 (1) Å. Other trigonally bound Cu(I) atoms link these units together to form the network. The Cu(II) atoms, coordinated by two meen units, are covalently linked to the network via a cyanide bridge, and project into the open network channels. In the mol-ecular compound (II), [(N-methylethylenediamine-κ(2)N,N')copper(II)]-μ(2)-cyanido-κ(2)C:N-[bis(cyanido-κC)copper(I)] monohydrate, [Cu2(CN)3(C3H10N2)2]·H2O or Cu2(CN)3meen2·H2O, a CN group connects a Cu(II) atom coordinated by two meen groups with a trigonal-planar Cu(I) atom coordinated by CN groups. The mol-ecules are linked into centrosymmetric dimers via hydrogen bonds to two water mol-ecules. In both compounds, the bridging cyanide between the Cu(II) and Cu(I) atoms has the N atom bonded to Cu(II) and the C atom bonded to Cu(I), and the Cu(II) atoms are in a square-pyramidal coordination.

  4. 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.

  5. Mixed-valence polyoxometalate clusters. III. Vibronic problem for the 2-electron reduced heteropoly blue with the Keggin structure

    NASA Astrophysics Data System (ADS)

    Borrás-Almenar, J. J.; Clemente, J. M.; Coronado, E.; Tsukerblat, B. S.

    1995-06-01

    A general approach to the vibronic problem of delocalized electronic pairs in mixed-valence compounds is developed and applied to understand the ways of electron delocalization in dodecanuclear polyoxometalate clusters containing two moving electrons. The interplay between electronic and vibronic interactions is examined. The electronic spectrum is shown to consist of two spin triplets 3T 1 and 3T 2 and three spin singlets 1A 1, 1E and 1T 2 levels determined by the double-transfer processes (parameter P). Jahn-Teller and pseudo-Jahn-Teller problems ( 3T1 + 3T2) ⊗ ( e + t2) and ( 1A1 + 1E + 1T2) ⊗ ( e + t2) have been considered in the framework of the Piepho-Krausz-Schatz model dealing with the only vibronic parameter. Several kinds of spatial electronic distribution have been found corresponding to the stable points of the energy surfaces. For spin-triplet states, potential surfaces contain six minima in e space corresponding to partially delocalized electronic pairs over four sides of the T d structure (limiting case of weak coupling), or delocalized over two opposite sides (limiting case of strong coupling). The former situation restricts electron delocalization to two of the three metal octahedra of each M 3O 12 triad in such a way that each electron moves over a tetrameric unit in which the metal sites are alternatively sharing edges and corners. In the t 2 space the electronic pair can be either delocalized over three sides, giving rise to a trigonal-type distortion of the cluster and a partial electron delocalization over two opposite M 3O 12 triads (four trigonal minima in the case of strong transfer or relatively weak vibronic interaction), or be completely localized (case of strong vibronic coupling). For spin-singlet states the system possesses a stable point in the high-symmetrical nuclear configuration, corresponding to a full delocalization of the electronic pairs in the Keggin cluster. The influence of vibronic interaction on the nature of the

  6. Trinuclear nickel complexes with triplesalen ligands: simultaneous occurrence of mixed valence and valence tautomerism in the oxidized species.

    PubMed

    Glaser, Thorsten; Heidemeier, Maik; Fröhlich, Roland; Hildebrandt, Peter; Bothe, Eberhart; Bill, Eckhard

    2005-07-25

    forms exhibit the phenomena of valence tautomerism and mixed valence simultaneously. The extent of delocalization of the radical species and of the Ni(III) species is discussed.

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

    PubMed

    Singh, Vijay; Major, Dan Thomas

    2016-04-04

    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.

  8. Mixed-Valence Nickel-Iron Dithiolate Models of the [NiFe]-Hydrogenase Active Site

    PubMed Central

    Schilter, David; Nilges, Mark J.; Chakrabarti, Mrinmoy; Lindahl, Paul A.; Rauchfuss, Thomas B.; Stein, Matthias

    2012-01-01

    A series of mixed-valence iron-nickel dithiolates is described. Oxidation of (diphosphine)Ni(dithiolate)Fe(CO)3 complexes 1, 2, and 3 with ferrocenium salts affords the corresponding tricarbonyl cations [(dppe)Ni(pdt)Fe(CO)3]+ ([1]+), [(dppe)Ni(edt)Fe(CO)3]+ ([2]+) and [(dcpe)Ni(pdt)Fe(CO)3]+ ([3]+), respectively, where dppe = Ph2PCH2CH2PPh2, dcpe = Cy2PCH2CH2PCy2, pdtH2 = HSCH2CH2CH2SH and edtH2 = HSCH2CH2SH. The cation [2]+ proved unstable, but the propanedithiolates are robust. IR and EPR spectroscopic measurements indicate that these species exist as Cs-symmetric species. Crystallographic characterization of [3]BF4 shows that Ni is square planar. Interaction of [1]BF4 with P-donor ligands (L) afforded a series of substituted derivatives of type [(dppe)Ni(pdt)Fe(CO)2L]BF4 for L = P(OPh)3 ([4a]BF4), P(p-C6H4Cl)3 ([4b]BF4), PPh2(2-py) ([4c]BF4), PPh2(OEt) ([4d]BF4), PPh3 ([4e]BF4), PPh2(o-C6H4OMe) ([4f]BF4), PPh2(o-C6H4OCH2OMe) ([4g]BF4), P(p-tol)3 ([4h]BF4), P(p-C6H4OMe)3 ([4i]BF4), PMePh2 ([4j]BF4). EPR analysis indicates that ethanedithiolate [2]+ exists as a single species at 110 K, whereas the propanedithiolate cations exist as a mixture of two conformers, which are proposed to be related through a flip of the chelate ring. Mössbauer spectra of 1 and oxidized S = ½ [4e]BF4 are both consistent with a low-spin Fe(i) state. The hyperfine coupling tensor of [4e]BF4 has a small isotropic component and significant anisotropy. DFT calculations using the BP86, B3LYP, and PBE0 exchange-correlation functionals agree with the structural and spectroscopic data, suggesting that the SOMOs in complexes of the present type are localized in a Fe(i)-centered d(z2) orbital. The DFT calculations allow an assignment of oxidation states of the metals and rationalization of the conformers detected by EPR spectroscopy. Treatment of [1]+ with CN- and compact basic phosphines results in complex reactions. With dppe, [1]+ undergoes quasi-disproportionation to give 1 and the

  9. An Unusually Delocalized Mixed-Valence State of a Cyanidometal-Bridged Compound Induced by Thermal Electron Transfer.

    PubMed

    Ma, Xiao; Lin, Chen-Sheng; Zhu, Xiao-Quan; Hu, Sheng-Min; Sheng, Tian-Lu; Wu, Xin-Tao

    2017-02-01

    The heterometallic complexes trans-[Cp(dppe)FeNCRu(o-bpy)CNFe(dppe)Cp][PF6 ]n (1[PF6 ]n , n=2, 3, 4; o-bpy=1,2-bis(2,2'-bipyridyl-6-yl)ethane, dppe=1,2-bis(diphenylphosphino)ethane, Cp=1,3-cyclopentadiene) in three distinct states have been synthesized and fully characterized. 1(3+) [PF6 ]3 and 1(4+) [PF6 ]4 are the one- and two-electron oxidation products of 1(2+) [PF6 ]2 , respectively. The investigated results suggest that 1[PF6 ]3 is a Class II mixed valence compound. 1[PF6 ]4 after a thermal treatment at 400 K shows an unusually delocalized mixed valence state of [Fe(III) -NC-Ru(III) -CN-Fe(II) ], which is induced by electron transfer from the central Ru(II) to the terminal Fe(III) in 1[PF6 ]4 , which was confirmed by IR spectroscopy, magnetic data, and EPR and Mössbauer spectroscopy.

  10. Mixed valency and site-preference chemistry for cerium and its compounds: A predictive density-functional theory study

    SciTech Connect

    Alam, Aftab; Johnson, Duane D.

    2014-06-01

    Cerium and its technologically relevant compounds are examples of anomalous mixed valency, originating from two competing oxidation states—itinerant Ce4+ and localized Ce3+. Under applied stress, anomalous transitions are observed but not well understood. Here we treat mixed valency as an “alloy” problem involving two valences with competing and numerous site-occupancy configurations. We use density-functional theory with Hubbard U (i.e., DFT+U) to evaluate the effective valence and predict properties, including controlling the valence by pseudoternary alloying. For Ce and its compounds, such as (Ce,La)2(Fe,Co)14B permanent magnets, we find a stable mixed-valent α state near the spectroscopic value of νs=3.53. Ce valency in compounds depends on its steric volume and local chemistry. For La doping, Ce valency shifts towards γ-like Ce3+, as expected from steric volume; for Co doping, valency depends on local Ce-site chemistry and steric volume. Our approach captures the key origins of anomalous valency and site-preference chemistry in complex compounds.

  11. A mixed-valence metallogrid [CoCo] with an unusual electronic structure and single-ion-magnet characterization.

    PubMed

    Huang, Wei; Pan, Feifei; Wang, Zhenxing; Bai, Yan; Feng, Xuejun; Gu, Jiande; Ouyang, Zhong-Wen; Wu, Dayu

    2017-04-11

    The reaction of the multisite coordination ligand (H2L) with Co(Ac)2·4H2O in the absence of any base affords a homometallic tetranuclear mixed-valence complex, [Co4(L)4(CH3CO2)2(CH3OH)2]·Et2O (1). This mixed-valence metallogrid [Co4(L)4(CH3CO2)2 (CH3OH)2]·Et2O (1) has been theoretically and experimentally analyzed to assign the valence and spin state in the form of trans-[Co-Co-Co-Co]. HF-EPR reveals the presence of axial anisotropy (D = -34.4 cm(-1)) with a significant transverse component (E = 9.5 cm(-1)) in the local high spin cobalt centers. Slow magnetic relaxation effects were observed in the presence of a dc field, demonstrating field-induced single ion magnetic behavior, which is associated with the unusual electronic structure of Co(ii) within the metallogrid.

  12. 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.

  13. Photoinduced radical generation and self-assembly of tetrathiafulvalene into the mixed-valence state in the poly(vinyl chloride) film under UV irradiation.

    PubMed

    Tanaka, Kazuo; Ishiguro, Fumiyasu; Chujo, Yoshiki

    2010-01-19

    The photoinduced self-assembly and the formation of the mixed-valence state of tetrathiafulvalene (TTF) in the solid state are reported. The polymer composites containing TTF in poly(vinyl chloride) (PVC) were prepared, and oxidation of TTF by chlorine radical generated by UV irradiation in PVC was investigated. The formation of the mixed-valence state of TTF in the composite films by UV irradiation was observed, and the resulting TTF radical species, including the mixed-valence state after the photopatterning, exhibited extremely high stability in the composite films. Finally, we performed the fabrication of the gradient materials of the radical concentrations on the TTF/PVC composites with the photopatterning.

  14. Excited-state mixed valence in a diphenyl hydrazine cation: Spectroscopic consequences of coupling and transition dipole moment orientation.

    PubMed

    Lockard, Jenny V; Zink, Jeffrey I; Trieber Ii, Dwight A; Konradsson, Asgeir E; Weaver, Michael N; Nelsen, Stephen F

    2005-02-17

    A quantitative model of mixed-valence excited-state spectroscopy is developed and applied to 2,3-diphenyl-2,3-diazabicyclo[2.2.2]octane. The lowest-energy excited state of this molecule arises from a transition from the ground state, where the charge is located on the hydrazine bridge, to an excited state where the charge is associated with one phenyl group or the other. Coupling splits the absorption band into two components with the lower-energy component being the most intense. The sign of the coupling, derived by using a neighboring orbital model, is positive. The transition dipole moments consist of parallel and antiparallel vector components, and selection rules for each are derived. Bandwidths are caused by progressions in totally symmetric modes determined from resonance Raman spectroscopic analysis. The absorption, emission, and Raman spectra are fit simultaneously with one parameter set.

  15. 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.

  16. Mixed-valence polyoxometalate clusters. II. Delocalization of electronic pairs in 18-site heteropoly blues with Wells-Dawson structure

    NASA Astrophysics Data System (ADS)

    Borrás-Almenar, J. J.; Clemente, J. M.; Coronado, E.; Tsukerblat, B. S.

    1995-06-01

    The problem of delocalization of two electrons in the 18-site Wells-Dawson polyoxometalate is examined from a general approach that takes into account both single- and double-transfer processes, as well as the Coulomb interactions between the two delocalized electrons. The electronic energy levels of this mixed-valence cluster are calculated and the conditions giving rise to the stabilization of a singlet ground spin state for the electronic pair are elucidated. It is shown that the spin pairing results from the simultaneous effects of single- and double-electron transfer processes, which are operative even when the two delocalized electrons are fairly widely separated in the Wells-Dawson structure.

  17. Synthesis of a Neutral Mixed-Valence Diferrocenyl Carborane for Molecular Quantum-Dot Cellular Automata Applications.

    PubMed

    Christie, John A; Forrest, Ryan P; Corcelli, Steven A; Wasio, Natalie A; Quardokus, Rebecca C; Brown, Ryan; Kandel, S Alex; Lu, Yuhui; Lent, Craig S; Henderson, Kenneth W

    2015-12-14

    The preparation of 7-Fc(+) -8-Fc-7,8-nido-[C2 B9 H10 ](-) (Fc(+) FcC2 B9 (-) ) demonstrates the successful incorporation of a carborane cage as an internal counteranion bridging between ferrocene and ferrocenium units. This neutral mixed-valence Fe(II) /Fe(III) complex overcomes the proximal electronic bias imposed by external counterions, a practical limitation in the use of molecular switches. A combination of UV/Vis-NIR spectroscopic and TD-DFT computational studies indicate that electron transfer within Fc(+) FcC2 B9 (-) is achieved through a bridge-mediated mechanism. This electronic framework therefore provides the possibility of an all-neutral null state, a key requirement for the implementation of quantum-dot cellular automata (QCA) molecular computing. The adhesion, ordering, and characterization of Fc(+) FcC2 B9 (-) on Au(111) has been observed by scanning tunneling microscopy.

  18. First-principles study of electronic, mechanical and optical properties of mixed valence SmB6

    NASA Astrophysics Data System (ADS)

    Xiao, Lihua; Su, Yuchang; Peng, Ping; Tang, Dongsheng

    2017-06-01

    The mechanical and optical properties, electronic structure, and theoretical hardness of mixed valence SmB6 are calculated from first principles using density functional theory. The calculated results are in excellent agreement with previously reported experiments and theory. The band structures of SmB6 reveal that this material has the qualities of a semiconductor with a minimum gap. The elastic constants, bulk modulus, shear modulus and Young’s moduli of SmB6 are obtained. The calculated results indicate that SmB6 is a brittle material. The calculated theoretical hardness is 24.00 GPa. The optical properties of SmB6 are discussed in detail. It is shown that SmB6 absorbs in the near infrared and visible light range. Therefore, SmB6 has the potential to be used as a heat-absorbing coating in order to shield objects from solar heat radiation.

  19. 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

    2013-12-02

    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. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. Nature of the magnetic ground state in the mixed valence compound CeRuSn: a single-crystal study.

    PubMed

    Fikáček, J; Prokleška, J; Prchal, J; Custers, J; Sechovský, V

    2013-10-16

    We report on detailed low-temperature measurements of the magnetization, the specific heat and the electrical resistivity on high-quality CeRuSn single crystals. The compound orders antiferromagnetically at T(N) = 2.8 K with the Ce(3+) ions locked within the a-c plane of the monoclinic structure. Magnetization shows that below T(N) CeRuSn undergoes a metamagnetic transition when applying a magnetic field of 1.5 and 0.8 T along the a- and c-axis, respectively. This transition manifests in a tremendous negative jump of ~25% in the magnetoresistance. The value of the saturated magnetization along the easy magnetization direction (c-axis) and the magnetic entropy above T(N) derived from specific heat data correspond to the scenario of only one third of the Ce ions in the compound being trivalent and carrying a stable Ce(3+) magnetic moment, whereas the other two thirds of the Ce ions are in a nonmagnetic tetravalent and/or mixed valence state. This is consistent with the low-temperature CeRuSn crystal structure i.e., a superstructure consisting of three unit cells of the CeCoAl type piled up along the c-axis, and in which the Ce(3+) ions are characterized by large distances from the Ru ligands while the Ce-Ru distances of the other Ce ions are much shorter causing a strong 4f-ligand hybridization and hence leading to tetravalent and/or mixed valence Ce ions.

  1. Frustrated spin-1/2 molecular magnetism in the mixed-valence antiferromagnets Ba3M Ru2O9 (M =In , Y, Lu)

    NASA Astrophysics Data System (ADS)

    Ziat, D.; Aczel, A. A.; Sinclair, R.; Chen, Q.; Zhou, H. D.; Williams, T. J.; Stone, M. B.; Verrier, A.; Quilliam, J. A.

    2017-05-01

    We have performed magnetic susceptibility, heat capacity, muon spin relaxation, and neutron-scattering measurements on three members of the family Ba3M Ru2O9 , where M =In , Y, and Lu. These systems consist of mixed-valence Ru dimers on a triangular lattice with antiferromagnetic interdimer exchange. Although previous work has argued that charge order within the dimers or intradimer double exchange plays an important role in determining the magnetic properties, our results suggest that the dimers are better described as molecular units due to significant orbital hybridization, resulting in one spin-1/2 moment distributed equally over the two Ru sites. These molecular building blocks form a frustrated, quasi-two-dimensional triangular lattice. Our zero- and longitudinal-field μ SR results indicate that the molecular moments develop a collective, static magnetic ground state, with oscillations of the zero-field muon spin polarization indicative of long-range magnetic order in the Lu sample. The static magnetism is much more disordered in the Y and In samples, but they do not appear to be conventional spin glasses.

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

    NASA Astrophysics Data System (ADS)

    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+2Mn4+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.

  3. Hydrothermal synthesis and crystal structure of a novel 1D molybdenum(V) phosphate with mixed-valence cobalt coordination cations

    NASA Astrophysics Data System (ADS)

    Guo, Hong-Xu; Liu, Shi-Xiong

    2005-05-01

    A novel 1D molybdenum(V) phosphate with mixed-valence cobalt coordination cation, Co II[Mo 6O 12(OH) 3(PO 4)(HPO 4) 3] 2[Co III(H 2O)(2,2'-bpy) 2] 2[Co II3(OH) 2(H 2O) 4]·2H 2O ( 1), has been synthesized by hydrothermal and characterized by single crystal X-ray diffraction. The title complex crystallizes in the triclinic system, space group P1¯, with a=12.8779(6), b=13.6862(10), c=15.1111(8) Å, α=97.141(2)°, β=99.1360(10)°, γ=116.719(4)°. The structure of the title polyoxometalate is based on Co II[Mo 6O 12(OH) 3(PO 4)(HPO 4) 3] 2 clusters connected together via [Co II3(OH) 2(H 2O) 4] trimers to give a new unusual 1D chain-like along the c-axis, where the Co[Mo 6P 4] 2 cluster unit is bonded by [Co III(H 2O)(2,2'-bpy) 2] unit.

  4. 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.

  5. 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.

  6. Crystallization Induced by Electrostatic Correlations in Vesicles of Mixed-Valence Ionic Amphiphiles

    NASA Astrophysics Data System (ADS)

    Leung, Cheuk Yui; Sknepnek, Rastko; Palmer, Liam; Vernizzi, Graziano; Greenfield, Megan; Stupp, Samuel; Bedzyk, Michael; Olvera de La Cruz, Monica

    2011-03-01

    Charged amphiphilic molecules, including molecules with biological motifs, have been predicted to organize into elastic membrane or crystalline shells with non-spherical shapes. We demonstrate that pure electrostatic interaction allow (-1) anionic water insoluble amphiphiles and (+3) cationic amphiphiles, which form only micelles in water, to co-assemble into buckled vesicles. The strong interaction between the +3 and -1 head groups increases the cohesive energy of the amphiphiles and favors the formation of crystallized membranes or shells that facet spontaneously into buckled shapes predicted by simulations of vesicles with heterogeneous elastic properties. In situ small-angle and wide-angle X-ray scattering (SAXS-WAXS) experiments conducted at the Advanced Photon Source DND-CAT confirm the presence of crystalline bilayers. Our simulations verify that ionic lateral correlations among the oppositely charged head groups of the co-assembled amphiphiles are responsible for the observed tail crystallization. This work was supported by the US Department of Energy, Office of Basic Energy Sciences, Division of Materials Sciences and Engineering (DOE Contract No. DE-FG02-08ER46539).

  7. Information flow in heterogeneously interacting systems.

    PubMed

    Yamaguti, Yutaka; Tsuda, Ichiro; Takahashi, Yoichiro

    2014-02-01

    Motivated by studies on the dynamics of heterogeneously interacting systems in neocortical neural networks, we studied heterogeneously-coupled chaotic systems. We used information-theoretic measures to investigate directions of information flow in heterogeneously coupled Rössler systems, which we selected as a typical chaotic system. In bi-directionally coupled systems, spontaneous and irregular switchings of the phase difference between two chaotic oscillators were observed. The direction of information transmission spontaneously switched in an intermittent manner, depending on the phase difference between the two systems. When two further oscillatory inputs are added to the coupled systems, this system dynamically selects one of the two inputs by synchronizing, selection depending on the internal phase differences between the two systems. These results indicate that the effective direction of information transmission dynamically changes, induced by a switching of phase differences between the two systems.

  8. 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.

  9. Nanosheets of Two-Dimensional Magnetic and Conducting Fe(II)/Fe(III) Mixed-Valence Metal-Organic Frameworks.

    PubMed

    Benmansour, Samia; Abhervé, Alexandre; Gómez-Claramunt, Patricia; Vallés-García, Cristina; Gómez-García, Carlos J

    2017-08-09

    We report the synthesis, magnetic properties, electrical conductivity, and delamination into thin nanosheets of two anilato-based Fe(II)/Fe(III) mixed-valence two-dimensional metal-organic frameworks (MOFs). Compounds [(H3O)(H2O)(phenazine)3][Fe(II)Fe(III)(C6O4X2)3]·12H2O [X = Cl (1) and Br (2)] present a honeycomb layered structure with an eclipsed packing that generates hexagonal channels containing the water molecules. Both compounds show ferrimagnetic ordering at ca. 2 K coexisting with electrical conductivity (with room temperature conductivities of 0.03 and 0.003 S/cm). Changing the X group from Cl to Br leads to a decrease in the ordering temperature and room temperature conductivity that is correlated with the decrease of the electronegativity of X. Despite the ionic charge of the anilato-based layers, these MOFs can be easily delaminated in thin nanosheets with the thickness of a few monolayers.

  10. EOMCC, MRPT, and TDDFT studies of charge transfer processes in mixed-valence compounds: application to the spiro molecule.

    PubMed

    Glaesemann, Kurt R; Govind, Niranjan; Krishnamoorthy, Sriram; Kowalski, Karol

    2010-08-26

    The proper description of electron transfer (ET) processes in mixed-valence compounds poses a significant challenge for commonly used theoretical approaches. In this paper we analyze the 1(2)A(2) and 2(2)A(2) potential energy surfaces of the Spiro cation (5,5'(4H,4H')-spirobi[cyclopenta[c]pyrrole]2,2',6,6'-tetrahydro cation) which is a frequently used model to study ET processes. We compare and contrast the results obtained with three different methods: multireference perturbation theory, equation-of-motion coupled cluster theory, time-dependent density functional theory. We demonstrate that the proper inclusion of dynamical correlation effects plays a crucial role in the description of an avoided crossing between potential energy surfaces. We also find that proper balancing of the ground- and excited-state correlation effects is especially challenging in the vicinity of the 1(2)A(2) and 2(2)A(2) avoided crossing region.

  11. 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.

  12. Metal-Metal Bonding in Trinuclear, Mixed-Valence [Ti3X12](4-) (X = F, Cl, Br, I) Face-Shared Complexes.

    PubMed

    Hewage, Jinasena W; Cavigliasso, Germán; Stranger, Robert

    2015-11-16

    Metal-metal bonding in structurally characterized In4Ti3Br12, comprising linear, mixed-valence d(1)d(2)d(1) face-shared [Ti3Br12](4-) units with a Ti-Ti separation of 3.087 Å and strong antiferromagnetic coupling (Θ = -1216 K), has been investigated using density functional theory. The antiferromagnetic configuration, in which the single d electron on each terminal Ti(III) (d(1)) metal center is aligned antiparallel to the two electrons occupying the central Ti(II) (d(2)) metal site, is shown to best agree with the reported structural and magnetic data and is consistent with an S = 0 ground state in which two of the four metal-based electrons are involved in a two-electron, three-center σ bond between the Ti atoms (formal Ti-Ti bond order of ∼0.5). However, the unpaired spin densities on the Ti sites indicate that while the metal-metal σ interaction is strong, the electrons are not fully paired off and consequently dominate the ground state antiferromagnetic coupling. The same overall partially delocalized bonding regime is predicted for the other three halide [Ti3X12](4-) (X = F, Cl, I) systems with the metal-metal bonding becoming weaker as the halide group is descended. The possibility of bond-stretch isomerism was also examined where one isomer has a symmetric structure with identical Ti-Ti bonds while the other is unsymmetric with one short and one long Ti-Ti bond. Although calculations indicate that the latter form is more stable, the barrier to interconversion between equivalent unsymmetric forms, where the short Ti-Ti bond is on one side of the trinuclear unit or the other, is relatively small such that at room temperature only the averaged (symmetric) structure is likely to be observed.

  13. Incipient class II mixed valency in a plutonium solid-state compound

    NASA Astrophysics Data System (ADS)

    Cary, Samantha K.; Galley, Shane S.; Marsh, Matthew L.; Hobart, David L.; Baumbach, Ryan E.; Cross, Justin N.; Stritzinger, Jared T.; Polinski, Matthew J.; Maron, Laurent; Albrecht-Schmitt, Thomas E.

    2017-09-01

    Electron transfer in mixed-valent transition-metal complexes, clusters and materials is ubiquitous in both natural and synthetic systems. The degree to which intervalence charge transfer (IVCT) occurs, dependent on the degree of delocalization, places these within class II or III of the Robin-Day system. In contrast to the d-block, compounds of f-block elements typically exhibit class I behaviour (no IVCT) because of localization of the valence electrons and poor spatial overlap between metal and ligand orbitals. Here, we report experimental and computational evidence for delocalization of 5f electrons in the mixed-valent PuIII/PuIV solid-state compound, Pu3(DPA)5(H2O)2 (DPA = 2,6-pyridinedicarboxylate). The properties of this compound are benchmarked by the pure PuIII and PuIV dipicolinate complexes, [PuIII(DPA)(H2O)4]Br and PuIV(DPA)2(H2O)3·3H2O, as well as by a second mixed-valent compound, PuIII[PuIV(DPA)3H0.5]2, that falls into class I instead. Metal-to-ligand charge transfer is involved in both the formation of Pu3(DPA)5(H2O)2 and in the IVCT.

  14. 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

  15. 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.

  16. Mixed-valence effects and metamagnetism in a two-band model of correlated electrons

    NASA Astrophysics Data System (ADS)

    Acquarone, M.; SpaŁek, J.; Ray, D. K.

    1986-03-01

    We discuss both continuous and discontinuous transitions form para- to ferromagnetism within a model of electrons in double degenerate and hybridized band. We transform out rigorously the hybridization and obtain a two-band model with the component bands of substantially different width. This band structure is approximated by a band and a level placed in the center of the band. The model is solved both with and without applied magnetic field, within the Hartree-Fock approximation for the intraband and the interband interactions, and treating the Coulomb interactions on the level exactly. The self-consistent solutions for the magnetic moment and the band filling are given allowing for a redistribution of particles between the band and the level. A number of ferromagnetic and mixed-valent-type of configurations is possible, leading to a possibility of appearance of ferromagnetism in a discontinuous way and without the Stoner condition being fulfilled at the transition. Such transition cannot be described within the standard Ginzburg-Landau theory obtained from the Stoner-Wohlfarth model for a single band. The obtained result are used to give a qualitative explanation of the main results observed for the systems Co(S 1 - xSe x) 2 and CoTi 1 - xAl x.

  17. Estimating flow heterogeneity in natural fracture systems

    NASA Astrophysics Data System (ADS)

    Leckenby, Robert J.; Sanderson, David J.; Lonergan, Lidia

    2005-10-01

    Examples of small to medium scale fault systems have been mapped in Jurassic sedimentary rocks in north Somerset, England. These examples include contractional and dilational strike-slip oversteps as well as normal faults. These maps form the basis of calculations performed to investigate heterogeneity in natural fracture systems with the aim of predicting fluid flow localisation in different fault styles. As there is no way to measure fracture aperture directly, we use vein thickness to represent an integrated flow path or 'palaeo-aperture' from which we derive a representation of the flow distribution. Three different methods are used to estimate flow heterogeneity based on: (1) fracture density (the ratio of fracture length to area), (2) fracture aperture (fracture porosity) and (3) hydraulic conductance (fracture permeability normalised to the pressure gradient and fluid properties). Our results show that fracture density and hydraulic conductance are poorly correlated and that fracture density does not fully represent the natural heterogeneity of fracture systems. Fracture aperture and hydraulic conductance indicate stronger degrees of flow localisation. Different types of structures also seem to display characteristic and predictable patterns of heterogeneity. Normal fault systems show the highest magnitude of localisation along the faults rather than in the relay ramps, while contractional and dilational strike-slip systems show very strong localisation in the faults and oversteps, respectively. In all cases the amount of damage in the oversteps can modify such patterns of heterogeneity.

  18. Hole Transfer Processes in meta- and para-Conjugated Mixed Valence Compounds: Unforeseen effects of bridge substituents and solvent dynamics.

    PubMed

    Schaefer, Julian; Holzapfel, Marco; Mladenova, Boryana; Kattnig, Daniel; Krummenacher, Ivo; Braunschweig, Holger; Grampp, Günter; Lambert, Christoph

    2017-04-12

    To address the question whether donor substituents can be utilized to accelerate the hole transfer (HT) between redox sites attached in para- or in meta-positions to a central benzene bridge we investigated three series of mixed valence compounds based on triarylamine redox centers that are connected to a benzene bridge via alkyne spacers at para- and meta-positions. The electron density at the bridge was tuned by substituents with different electron donating or accepting character. By analyzing optical spectra and by DFT computations we show that the HT properties are independent of bridge substituents for one of the meta-series, while donor substituents can strongly decrease the intrinsic barrier in the case of the para-series. In stark contrast, temperature-dependent ESR measurements demonstrate a dramatic increase of both the apparent barrier and the rate of HT for strong donor substituents in the para-cases. This is caused by an unprecedented substituent-dependent change of the HT mechanism from that described by transition state theory to a regime controlled by solvent dynamics. For solvents with slow longitudinal relaxation (PhNO2, oDCB), this adds an additional contribution to the intrinsic barrier via the dielectric relaxation process. Attaching the donor substituents to the bridge at positions where the molecular orbital coefficients are large accelerates the HT rate for meta-conjugated compounds just as for the para-series. This effect demonstrates that the para-meta paradigm no longer holds if appropriate substituents and substitution patterns are chosen, thereby considerably broadening the applicability of meta-topologies for optoelectronic applications.

  19. Ligand redox activity and mixed valency in first-row transition-metal complexes containing tetrachlorocatecholate and radical tetrachlorosemiquinonate ligands.

    PubMed

    Pierpont, Cortlandt G

    2011-10-17

    Ligand noninnocence occurs for complexes composed of redox-active ligands and metals, with frontier orbitals of similar energy. Usually methods of analysis can be used to define the charge distribution, and cases where the metal oxidation state and ligand charge are unclear are unusual. Ligands derived from o-benzoquinones can bond with metals as radical semiquinonates (SQ(•-)) or as catecholates (Cat(2-)). Spectroscopic, magnetic, and structural properties can be used to assess the metal and ligand charges. With the redox activity at both the metal and ligands, reversible multicomponent redox series can be observed using electrochemical methods. Steps in the series may occur at either the ligand or metal, and ligand substituent effects can be used to tune the range of ligand-based redox steps. Complexes that appear as intermediates in a ligand-based redox series may contain both SQ and Cat ligands "bridged" by the metal as mixed-valence complexes. Properties reflect the strength of metal-mediated interligand electronic coupling in the same way that ligand-bridged bimetallics conform to the Robin and Day classification scheme. In this review, we will focus specifically on complexes of first-row transition-metal ions coordinated with three ligands derived from tetrachloro-1,2-benzoquinone (Cl(4)BQ). The redox activity of this ligand overlaps with the potentials of common metal oxidation states, providing examples of metal- and ligand-based redox activity, in some cases, within a single redox series. The strength of the interligand electronic coupling is important in defining the separation between ligand-based couples of a redox series. The complex of ferric iron will be described as an example where coupling is weak, and the steps associated with the Fe(III)(Cl(4)SQ)(3)/[Fe(III)(Cl(4)Cat)(3)](3-) redox series are observed over a narrow range in electrochemical potential.

  20. 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.

  1. Pressure effects and Mössbauer spectroscopic studies on a 3D mixed-valence iron spin-crossover complex with NiAs topology.

    PubMed

    Bai, Yue-Ling; Tao, Jun; Huang, Rong-Bin; Zheng, Lan-Sun; Zheng, Shao-Liang; Oshida, Kazuyoshi; Einaga, Yasuaki

    2008-04-21

    A three-dimensional mixed-valence iron complex with NiAs-type topology, [(Fe(III)(3)O)Fe(II)(TA)(6)(H(2)O)(3)].(ClO(4))(2)(NO(3))(EtOH)(H(2)O)(2) (1, HTA = tetrazole-1H-acetic acid), shows spin-crossover behavior that was characterized via variable-temperature crystal structures, Mössbauer spectra and magnetic susceptibilities, the pressure effects on the transition behavior were also studied.

  2. Simulating Ru L 3 -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, Nils; Schoenlein, Robert W.; Govind, Niranjan; Khalil, Munira

    2013-05-30

    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.

  3. 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.

  4. Crystal structures of two mixed-valence copper cyanide complexes with N-methyl­ethylenedi­amine

    PubMed Central

    Sabatino, Alexander

    2017-01-01

    The crystal structures of two mixed-valence copper cyanide compounds involving N-methyl­ethylenedi­amine (meen), are described. In compound (I), poly[bis(μ3-cyanido-κ3 C:C:N)tris(μ2-cyanido-κ2 C:N)bis(N-methylethane-1,2-di­amine-κ2 N,N′)tricopper(I)copper(II)], [Cu4(CN)5(C3H10N2)2] or Cu4(CN)5meen2, cyanide groups link CuI atoms into a three-dimensional network containing open channels parallel to the b axis. In the network, two tetra­hedrally bound CuI atoms are bonded by the C atoms of two end-on bridging CN groups to form Cu2(CN)6 moieties with the Cu atoms in close contact at 2.560 (1) Å. Other trigonally bound CuI atoms link these units together to form the network. The CuII atoms, coordinated by two meen units, are covalently linked to the network via a cyanide bridge, and project into the open network channels. In the mol­ecular compound (II), [(N-methylethylenediamine-κ2 N,N′)copper(II)]-μ2-cyanido-κ2 C:N-[bis(cyanido-κC)copper(I)] monohydrate, [Cu2(CN)3(C3H10N2)2]·H2O or Cu2(CN)3meen2·H2O, a CN group connects a CuII atom coordinated by two meen groups with a trigonal–planar CuI atom coordinated by CN groups. The mol­ecules are linked into centrosymmetric dimers via hydrogen bonds to two water mol­ecules. In both compounds, the bridging cyanide between the CuII and CuI atoms has the N atom bonded to CuII and the C atom bonded to CuI, and the CuII atoms are in a square-pyramidal coordination. PMID:28217329

  5. 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.

  6. High nuclearity single-molecule magnets: a mixed-valence Mn26 cluster containing the di-2-pyridylketone diolate dianion.

    PubMed

    Stamatatos, Theocharis C; Nastopoulos, Vassilios; Tasiopoulos, Anastasios J; Moushi, Eleni E; Wernsdorfer, Wolfgang; Christou, George; Perlepes, Spyros P

    2008-11-03

    The employment of the dianion (dpkd(2-)) of the gem-diol form of di-2-pyridylketone (dpk) as a tetradentate chelate in manganese chemistry is reported, and the synthesis, crystal structure, and magnetochemical characterization of [Mn26O16(OMe)12(dpkd)12(MeOH)6](OH)6 x solv (3 x solv) are described. The reaction of Mn(ClO4)2 x 6 H2O, dpk, NaOMe, and NEt3 (2:1:4:2) in MeCN/MeOH affords complex 3, which possesses a rare metal topology and is mixed-valence (4 Mn(II), 22 Mn(III)). The complicated [Mn26(mu4-O)10(mu3-O)6(mu3-OMe)12(mu-OR)12](18+) core of 3 consists of an internal Mn(III)16 cage of adjacent Mn4 tetrahedra surrounded by an external Mn(II)4Mn(III)6 shell. The latter is held together by the alkoxide arms of twelve eta(1):eta(2):eta(1):eta(1):mu3 dpkd(2-) groups. Variable-temperature, solid-state direct current (dc), and alternating current (ac) magnetization studies were carried out on 3 in the 1.8-300 K range. Complex 3 is predominantly antiferromagnetically coupled with a resulting S = 6 ground state, a conclusion confirmed by the in-phase (chi'(M)) ac susceptibility data. The observation of out-of-phase (chi''(M)) ac susceptibility signals suggested that 3 might be a single-molecule magnet, and this was confirmed by single-crystal magnetization vs dc field sweeps that exhibited hysteresis, the diagnostic property of a magnet. Combined ac chi''(M) and magnetization decay vs time data collected below 1.1 K were used to construct an Arrhenius plot; the fit of the thermally activated region above approximately 0.1 K gave U(eff) = 30 K, where U(eff) is the effective relaxation barrier. At lower temperatures, the complex exhibits temperature-independent relaxation, characteristic of ground-state quantum tunneling of magnetization between the lowest-lying M(s) = +/-6 levels. The combined work demonstrates the ligating flexibility of dipyridyl-diolate chelates and their usefulness in the synthesis of polynuclear Mn(x) clusters with interesting magnetic properties

  7. Dynamical Systems Approach to Endothelial Heterogeneity

    PubMed Central

    Regan, Erzsébet Ravasz; Aird, William C.

    2012-01-01

    Rationale Objective Here we reexamine our current understanding of the molecular basis of endothelial heterogeneity. We introduce multistability as a new explanatory framework in vascular biology. Methods We draw on the field of non-linear dynamics to propose a dynamical systems framework for modeling multistability and its derivative properties, including robustness, memory, and plasticity. Conclusions Our perspective allows for both a conceptual and quantitative description of system-level features of endothelial regulation. PMID:22723222

  8. 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

  9. 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

    2016-08-09

    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

  10. Heterogeneous distributed query processing: The DAVID system

    NASA Technical Reports Server (NTRS)

    Jacobs, Barry E.

    1985-01-01

    The objective of the Distributed Access View Integrated Database (DAVID) project is the development of an easy to use computer system with which NASA scientists, engineers and administrators can uniformly access distributed heterogeneous databases. Basically, DAVID will be a database management system that sits alongside already existing database and file management systems. Its function is to enable users to access the data in other languages and file systems without having to learn the data manipulation languages. Given here is an outline of a talk on the DAVID project and several charts.

  11. Independent Noise Enhances Synchronization in Heterogeneous Systems

    NASA Astrophysics Data System (ADS)

    Uchida, Go; Tanifuji, Manabu

    2014-09-01

    We investigated effects of noise inputs on synchronous firing in a simple model neuron system with electrophysiological heterogeneity. The system consists of two leaky integrate-and-fire (LIF) neurons with different membrane time constants. They are uncoupled and driven by Gaussian white noise inputs. We found that correlation between spike trains of two LIF neurons was maximized at input correlation slightly smaller than one. The same result was obtained for a more realistic system consisting of two non-identical Hodgkin-Huxley neurons. We also revealed the mechanism underlying the effect.

  12. Charge transfer phase transition with reversed thermal hysteresis loop in the mixed-valence Fe9[W(CN)8]6·xMeOH cluster.

    PubMed

    Chorazy, Szymon; Podgajny, Robert; Nogaś, Wojciech; Nitek, Wojciech; Kozieł, Marcin; Rams, Michał; Juszyńska-Gałązka, Ewa; Żukrowski, Jan; Kapusta, Czesław; Nakabayashi, Koji; Fujimoto, Takashi; Ohkoshi, Shin-ichi; Sieklucka, Barbara

    2014-04-04

    A bimetallic pentadecanuclear cyanido-bridged {Fe9[W(CN)8]6 (MeOH)24}·xMeOH cluster of an Fe(II/III)-W(IV/V) mixed valence nature, reveals a reversible single-crystal-to-single-crystal transformation, concomitant with metal-to-metal charge transfer between Fe and W ions. The dominance of (HS)Fe(II)-NC-W(V) units at a high temperature, and (HS)Fe(III)-NC-W(IV) units at a low temperature, leads to an unprecedented reversed thermal hysteresis loop in magnetic measurements.

  13. Spatial Heterogeneity of Autoinducer Regulation Systems

    PubMed Central

    Hense, Burkhard A.; Müller, Johannes; Kuttler, Christina; Hartmann, Anton

    2012-01-01

    Autoinducer signals enable coordinated behaviour of bacterial populations, a phenomenon originally described as quorum sensing. Autoinducer systems are often controlled by environmental substances as nutrients or secondary metabolites (signals) from neighbouring organisms. In cell aggregates and biofilms gradients of signals and environmental substances emerge. Mathematical modelling is used to analyse the functioning of the system. We find that the autoinducer regulation network generates spatially heterogeneous behaviour, up to a kind of multicellularity-like division of work, especially under nutrient-controlled conditions. A hybrid push/pull concept is proposed to explain the ecological function. The analysis allows to explain hitherto seemingly contradicting experimental findings. PMID:22666024

  14. A Transition from Localized to Strongly Correlated Electron Behavior and Mixed Valence Driven by Physical or Chemical Pressure in ACo2As2 (A = Eu and Ca).

    PubMed

    Tan, Xiaoyan; Fabbris, Gilberto; Haskel, Daniel; Yaroslavtsev, Alexander A; Cao, Huibo; Thompson, Corey M; Kovnir, Kirill; Menushenkov, Alexey P; Chernikov, Roman V; Garlea, V Ovidiu; Shatruk, Michael

    2016-03-02

    We demonstrate that the action of physical pressure, chemical compression, or aliovalent substitution in ACo2As2 (A = Eu and Ca) has a general consequence of causing these antiferromagnetic materials to become ferromagnets. In all cases, the mixed valence triggered at the electropositive A site results in the increase of the Co 3d density of states at the Fermi level. Remarkably, the dramatic alteration of magnetic behavior results from the very minor (<0.15 electron) change in the population of the 3d orbitals. The mixed valence state of Eu observed in the high-pressure (HP) form of EuCo2As2 exhibits a remarkable stability, achieving the average oxidation state of +2.25 at 12.6 GPa. In the case of CaCo2As2, substituting even 10% of Eu or La into the Ca site causes ferromagnetic ordering of Co moments. Similar to HP-EuCo2As2, the itinerant 3d ferromagnetism emerges from electronic doping into the Co layer because of chemical compression of Eu sites in Ca0.9Eu0.1Co1.91As2 or direct electron doping in Ca0.85La0.15Co1.89As2. The results reported herein demonstrate the general possibility of amplifying minor localized electronic effects to achieve major changes in material's properties via involvement of strongly correlated electrons.

  15. A Transition from Localized to Strongly Correlated Electron Behavior and Mixed Valence Driven by Physical or Chemical Pressure in ACo2As2 (A = Eu and Ca)

    SciTech Connect

    Tan, Xiaoyan; Fabbris, Gilberto; Haskel, Daniel; Yaroslavtsev, Alexander A.; Cao, H.; Thompson, Corey M.; Kovnir, Kirill; Menushenkov, Alexey P.; Chernikov, Roman V.; Garlea, V. Ovidiu; Shatruk, Michael

    2016-03-02

    We demonstrate that the action of physical pressure, chemical compression, or aliovalent substitution in ACo(2)As(2) (A = Eu and Ca) has a general consequence of causing these antiferromagnetic materials to become ferromagnets. In all cases, the mixed valence triggered at the electropositive A site results in the increase of the Co 3d density of states at the Fermi level. Remarkably, the dramatic alteration of magnetic behavior results from the very minor (<0.15 eleetron) change in the population of the 3d orbitals. The mixed valence state of En observed in the high-pressure (HP) form of EuCo2As2 exhibits a remarkable stability, achieving the average oxidation state of +2.25 at 12.6 GPa. In the case of CaCo2As2, substituting even 10% of Eu or La into the Ca site causes ferromagnetic ordering of Co moments. Similar to HP-EuCo2As2, the itinerant 3d ferromagnetism emerges from electronic doping into the Co layer because of chemical compression of Eu sites in Ca0.9Eu0.1Co1.91As2 or direct electron doping in Ca0.85La0.15Co1.89As2. The results reported herein demonstrate the general possibility of amplifying minor localized electronic effects to achieve major changes in material's properties via involvement of strongly correlated electrons.

  16. Hybrid Langmuir and Langmuir-Blodgett films of a viologen derivative and TCNQ in a mixed valence state: preparation route and characterization

    NASA Astrophysics Data System (ADS)

    Martín, Santiago; Cea, Pilar; Lafuente, Carlos; Royo, Félix M.; López, María. C.

    2004-08-01

    Hybrid Langmuir and Langmuir-Blodgett (LB) films containing two moieties of great chemical and electrochemical interest, namely a viologen derivative and tetracyanoquinodimethane (TCNQ) in a mixed valence state, were fabricated. To do so, positively ionized monolayers of 1,1 '-dioctadecyl 4,4 '-bipyridilium were prepared onto aqueous solutions of tetracyanoquinodimethane in a mixed valence state. Surface pressure vs. area ( π- A), surface potential vs. area (Δ V- A), and Brewster angle microscope (BAM) images were recorded and interpreted in terms of molecular interactions as well as the incorporation of the hydrophobic anions into the monolayer. After a comprehensive study, a 10 -6 M TCNQ aqueous solution was chosen as the best one to build hybrid LB films. Thus, the floating films were transferred onto solid substrates that were characterized using several techniques including ultraviolet-visible (UV-vis), infrared (IR), scanning electron microscopy (SEM), and atomic force microscopy (AFM) proving the incorporation of the TCNQ onto the film. These films show a good optical conductivity as well as a high degree of order and layers with a constant architecture.

  17. A Transition from Localized to Strongly Correlated Electron Behavior and Mixed Valence Driven by Physical or Chemical Pressure in ACo2As2 (A = Eu and Ca)

    DOE PAGES

    Tan, Xiaoyan; Fabbris, Gilberto; Haskel, Daniel; ...

    2016-02-03

    In this paper, we demonstrate that the action of physical pressure, chemical compression, or aliovalent substitution in ACo2As2 (A = Eu and Ca) has a general consequence of causing these antiferromagnetic materials to become ferromagnets. In all cases, the mixed valence triggered at the electropositive A site results in the increase of the Co 3d density of states at the Fermi level. Remarkably, the dramatic alteration of magnetic behavior results from the very minor (<0.15 electron) change in the population of the 3d orbitals. The mixed valence state of Eu observed in the high-pressure (HP) form of EuCo2As2 exhibits amore » remarkable stability, achieving the average oxidation state of +2.25 at 12.6 GPa. In the case of CaCo2As2, substituting even 10% of Eu or La into the Ca site causes ferromagnetic ordering of Co moments. Similar to HP-EuCo2As2, the itinerant 3d ferromagnetism emerges from electronic doping into the Co layer because of chemical compression of Eu sites in Ca0.9Eu0.1Co1.91As2 or direct electron doping in Ca0.85La0.15Co1.89As2. Finally, the results reported herein demonstrate the general possibility of amplifying minor localized electronic effects to achieve major changes in material’s properties via involvement of strongly correlated electrons.« less

  18. 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.

  19. New route to the mixed valence semiquinone-catecholate based mononuclear FeIII and catecholate based dinuclear MnIII complexes: first experimental evidence of valence tautomerism in an iron complex.

    PubMed

    Shaikh, Nizamuddin; Goswami, Sanchita; Panja, Anangamohan; Wang, Xin-Yi; Gao, Song; Butcher, Ray J; Banerjee, Pradyot

    2004-09-20

    The semiquinone-catecholate based mixed valence complex, [FeIII(bispicen)(Cl4Cat)(Cl4SQ)] x DMF (1), and catecholate based (H2bispictn)[Mn2III(Cl4Cat)4(DMF)2] (2) (bispicen = N,N'-bis(2-pyridylmethyl)-1,2-ethanediamine, bispictn = N,N'-bis(2-pyridylmethyl)-1,3-propanediamine, Cl4Cat = tetrachlorocatecholate dianion, and Cl4SQ = tetrachlorosemiquinone radical anion) were synthesized directly utilizing a facile route. Both the complexes have been characterized by single crystal X-ray diffraction study. The electronic structures have been elucidated by UV-vis-NIR absorption spectroscopy, cyclic voltammetry, EPR, and magnetic properties. The structural as well as spectroscopic features support the mixed valence tetrachlorosemiquinone-tetrachlorocatecholate charge distribution in 1. The ligand based mixed valence state was further confirmed by the presence of an intervalence charge transfer (IVCT) band in the 1900 nm region both in solution and in the solid. The intramolecular electron transfer, a phenomenon known as valence tautomerism (VT), has been followed by electronic absorption spectroscopy. For 1, the isomeric form [FeIII(bispicen)(Cl4Cat)(Cl4SQ)] is favored at low temperature, while at an elevated temperature, the [FeII(bispicen)(Cl4SQ)2] redox isomer dominates. Infrared as well as UV-vis-NIR spectral characterization for 2 suggest that the MnIII(Cat)2- moiety is admixed with its mixed valence semiquinone-catecholate isomer MnII(SQ)(Cat)-, and the electronic absorption spectrum is dominated by the mixed charged species. The origin of the intervalence charge transfer band in the 1900 nm range is associated with the mixed valence form, MnII(Cl4Cat)(Cl4SQ)-. The observation of VT in complex 1 is the first example where a mixed valence semiquinone-catecholate iron(III) complex undergoes intramolecular electron transfer similar to manganese and cobalt complexes.

  20. [V16O38(CN)]9–: a soluble mixed-valence redox-active building block with strong antiferromagnetic coupling.

    PubMed

    Keene, Tony D; D'Alessandro, Deanna M; Krämer, Karl W; Price, Jason R; Price, David J; Decurtins, Silvio; Kepert, Cameron J

    2012-09-03

    A new discrete [V(16)O(38)(CN)](9-) cluster, which displays the hitherto unknown 8- charge on the cluster shell and is the first to encapsulate the cyanide anion, has been synthesized and characterized by IR and UV/vis/near-IR spectroscopy, electrochemistry, and magnetic susceptibility measurements. Bond valence sum calculations conducted on the basis of the crystal structure analysis of K(9)[V(16)O(38)(CN)]·13H(2)O confirm that this new member of the polyoxovanadate series is a mixed-valence complex. The intervalence charge transfer bands arising from intrametal interactions reveal that a localized (class II) assignment is appropriate for the cluster; however, a small degree of electronic delocalization is present. Interesting possibilities exist for the incorporation of this unit into higher dimensionality framework structures, where the redox, optical, and magnetic properties can be exploited and tuned.

  1. Ferromagnetic behavior in mixed valence europium (Eu2+/Eu3+) oxide EuTi1-xMxO3 (M = Al3+ and Ga3+)

    NASA Astrophysics Data System (ADS)

    Akahoshi, Daisuke; Horie, Hiroki; Sakai, Shingo; Saito, Toshiaki

    2013-10-01

    We have investigated the Ti-site substitution effect on the magnetic properties of antiferromagnetic insulator EuTiO3 with a Néel temperature of ˜5 K. Partial substitution of Ti4+ with heterovalent Al3+ or Ga3+ turns the corresponding amount of magnetic Eu2+ into non-magnetic Eu3+. Both EuTi1-xAlxO3 (0.05 ≤ x ≤ 0.10) and EuTi1-xGaxO3 (0.05 ≤ x ≤ 0.10) exhibit ferromagnetic (FM) insulating behavior below ˜4 K. The Eu2+/Eu3+ mixed valence state probably contributes to the emergence of the FM behavior. Fine control of the magneto-electric (ME) phases of EuTi1-xAlxO3 and EuTi1-xGaxO3 would lead to intriguing ME phenomena such as giant ME effect.

  2. 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.

  3. 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.

  4. Intensely colored mixed-valence iron(II) iron(III) formate analogue of Prussian Blue exhibits néel N-type ferrimagnetism.

    PubMed

    Hagen, Karl S; Naik, Sunil G; Huynh, Boi Hanh; Masello, Antonio; Christou, George

    2009-06-10

    The reaction of colorless iron(II) formate or the mixed-valence cluster Fe(3)O(MeCOO)(6)(H(2)O)(3) with formic acid in dimethylformamide exposed to air at 110 degrees C affords black crystals of the mixed-valence (Me(2)NH(2))[Fe(II)Fe(III)(HCOO)(6)] three-dimensional (3D) structure in which the cations occupy half of the channels. The structure consists of alternating layers of Fe(II)O(6) [Fe(1)-O(1), 2.119(1) A] and Fe(III)O(6) [Fe(2)-O(2), 2.0049(9) A] octahedra bridged by anti-anti-bonded formates to afford an open-framework 3D structure. The structure is very similar to those of (Me(2)NH(2))[Fe(II)(HCOO)(3)] and [Fe(III)(HCOO)(3)].HCOOH, both of which are colorless. The black crystals appear dark-purple (lambda(max) approximately 520 nm) when powdered. The room-temperature Mössbauer spectrum confirms the 1:1 ratio of Fe(II) (delta = 1.03 mm/s, DeltaE(Q) = 1.16 mm/s) and Fe(III) (delta = 0.62 mm/s, DeltaE (Q) = 0.49 mm/s). Magnetic ordering that includes negative magnetization at low fields occurs at low temperature. The only molecular-based magnetic materials in which this phenomenon has been observed are the 2D polyiron(II,III) oxalates A[Fe(II)Fe(III)(C(2)O(4))(3)] (A = R(4)N(+) cation).

  5. Spectroscopic and Kinetic Investigation of the Fully Reduced and Mixed Valence States of ba3-Cytochrome c Oxidase from Thermus thermophilus

    PubMed Central

    Koutsoupakis, Constantinos; Soulimane, Tewfik; Varotsis, Constantinos

    2012-01-01

    The complete understanding of a molecular mechanism of action requires the thermodynamic and kinetic characterization of different states and intermediates. Cytochrome c oxidase reduces O2 to H2O, a reaction coupled to proton translocation across the membrane. Therefore, it is necessary to undertake a thorough characterization of the reduced form of the enzyme and the determination of the electron transfer processes and pathways between the redox-active centers. In this study Fourier transform infrared (FTIR) and time-resolved step-scan FTIR spectroscopy have been applied to study the fully reduced and mixed valence states of cytochrome ba3 from Thermus thermophilus. We used as probe carbon monoxide (CO) to characterize both thermodynamically and kinetically the cytochrome ba3-CO complex in the 5.25–10.10 pH/pD range and to study the reverse intramolecular electron transfer initiated by the photolysis of CO in the two-electron reduced form. The time-resolved step-scan FTIR data revealed no pH/pD dependence in both the decay of the transient CuB1+-CO complex and rebinding to heme a3 rates, suggesting that no structural change takes place in the vicinity of the binuclear center. Surprisingly, photodissociation of CO from the mixed valence form of the enzyme does not lead to reverse electron transfer from the reduced heme a3 to the oxidized low-spin heme b, as observed in all the other aa3 and bo3 oxidases previously examined. The heme b-heme a3 electron transfer is guaranteed, and therefore, there is no need for structural rearrangements and complex synchronized cooperativities. Comparison among the available structures of ba3- and aa3-cytochrome c oxidases identifies possible active pathways involved in the electron transfer processes and key structural elements that contribute to the different behavior observed in cytochrome ba3. PMID:22927441

  6. 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.

  7. Declustering databases on heterogeneous disk systems

    SciTech Connect

    Chen, Ling T.; Rotem, D.; Seshadri, S.

    1995-04-01

    Declustering is a well known strategy to achieve maximum I/O parallelism in multi-disk systems. Many declustering methods have been proposed for symmetrical disk systems, i.e., multi-disk systems in which all disks have the same speed and capacity. This work deals with the problem of adapting such declustering methods to work in heterogeneous environments. In such environments these are many types of disks and servers with a large range of speeds and capacities. We deal first with the case of perfectly declustered queries, i.e., queries which retrieve a fixed proportion of the answer from each disk. We show that the fraction of the dataset which must be allocated to each disk is affected by both the relative speed and capacity of the disk. Furthermore, the hierarchical structure of most distributed systems, where groups of disks are placed in servers, imposes further complications due to variations . in server and network bandwidths which may affect the actual achievable transfer rates. We propose an algorithm which determines the fraction of the dataset which must be loaded on each disk. The algorithm may be tailored to find disk loading for minimal response time for a given database size, or to compute a system profile showing the optimal loading of the disks for all possible ranges of database sizes. Next we look at the probabilistic aspects of this problem and show how to optimize the expected retrieval time when the Proportions of the data retrieved from each disk axe random variables. We show the rather surprising result that in this case to achieve optimality, the fraction of the data loaded on each disk must not simply be proportional to its speed but rather some compensation must be made with bias towards the faster disks. The methods proposed here are general and can be used in conjunction with most known symmetric declustering methods.

  8. 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.

  9. Synthesis of new mixed valence compounds MV{sup 5+}V{sub 2}{sup 4+}O{sub 7}(M=NH{sub 4},K): Crystal structure of NH{sub 4}V{sub 3}O{sub 7} and electrical properties of KV{sub 3}O{sub 7}

    SciTech Connect

    Trombe, J.C. Szajwaj, O.; Salles, Ph.; Galy, Jean

    2007-07-15

    A new mixed valence compound, NH{sub 4}V{sub 3}O{sub 7}, as single crystals, has been synthesized hydrothermally. It crystallizes in the monoclinic system, space group I2/m with lattice parameters a=12.198(1)A, b=3.7530(2)A, c=13.178(1)A, {beta}=100.532(6){sup o}, V=593.11(7)A{sup 3}, Z=4. The crystal structure determined with R=0.038 consists of (V{sub 3}O{sub 7}){sub n} layers linked by ammonium cations. The layer is built up by replication through symmetry elements of three independent distorted octahedra sharing edges and corners. The distortion of vanadium octahedra tends to vary and the coordination number CN is reasonably selected as equal to 5+1. KV{sub 3}O{sub 7}, synthesized by the mild hydrothermal route as a largely pure phase, is isostructural and its semi-conductive character is indicative of the presence of V{sup 4+} and V{sup 5+} sites. These are mixed valence compounds MV{sup 5+}V{sub 2}{sup 4+}O{sub 7}, the vanadium localization on three independent crystallographic sites enabling their electric behavior by electron hopping.

  10. Beamforming for Radar Systems on COTS Heterogeneous Computing Platforms

    DTIC Science & Technology

    2004-08-20

    Beamforming for Radar Systems on COTS Heterogeneous Computing Platforms Mr. Jeffrey Rudin Mercury Computer Systems, Inc. Phone: (978) 967-1686...ELEMENT NUMBER 6. AUTHOR(S) 5d. PROJECT NUMBER 5e. TASK NUMBER 5f. WORK UNIT NUMBER 7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) Mercury ...allocation and the resulting system topologies. © 2003 Mercury Computer Systems, Inc. Beamforming for Radar Systems on COTS Heterogeneous

  11. 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

    2016-09-06

    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

  12. A new generation of metal string complexes: structure, magnetism, spectroscopy, theoretical analysis, and single molecular conductance of an unusual mixed-valence linear [Ni5]8+ complex.

    PubMed

    Liu, Isiah Po-Chun; Bénard, Marc; Hasanov, Hasan; Chen, I-Wen Peter; Tseng, Wei-Hsiang; Fu, Ming-Dung; Rohmer, Marie-Madeleine; Chen, Chun-hsien; Lee, Gene-Hsiang; Peng, Shie-Ming

    2007-01-01

    Two new linear pentanickel complexes [Ni5(bna)4(Cl)2][PF6]2 (1) and [Ni5(bna)4(Cl)2][PF6]4 (2; bna=binaphthyridylamide), were synthesized and structurally characterized. A derivative of 1, [Ni5(bna)4(NCS)2][NCS]2 (3), was also isolated for the purpose of the conductance experiments carried out in comparison with [Ni5(tpda)4(NCS)2] (4; tpda=tripyridyldiamide). The metal framework of complex 2 is a standard [Ni5]10+ core, isoelectronic with that of [Ni5(tpda)4Cl2] (5). Also as in 5, complex 2 has an antiferromagnetic ground state (J=-15.86 cm(-1)) resulting from a coupling between the terminal nickel atoms, both in high-spin sate (S=1). Complex 1 displays the first characterized linear nickel framework in which the usual sequence of NiII atoms has been reduced by two electrons. Each dinickel unit attached to the naphthyridyl moieties is assumed to undergo a one-electron reduction, whereas the central nickel formally remains NiII. DFT calculations suggest that the metal framework of the mixed-valence complex 1 should be described as intermediate between a localized picture corresponding to NiII-NiI-NiII-NiI-NiII and a fully delocalized model represented as (Ni2)3+-NiII-(Ni2)3+. Assuming the latter model, the ground state of 1 results from an antiferromagnetic coupling (J=-34.03 cm(-1)) between the two (Ni2)3+ fragments, considered each as a single magnetic centre (S=3/2). An intervalence charge-transfer band is observed in the NIR spectrum of 1 at 1186 nm, suggesting, in accordance with DFT calculations, that 1 should be assigned to Robin-Day class II of mixed-valent complexes. Scanning tunnelling microscopy (STM) methodology was used to assess the conductance of single molecules of 3 and 4. Compound 3 was found approximately 40% more conductive than 4, a result that could be assigned to the electron mobility induced by mixed-valency in the naphthyridyl fragments.

  13. Programming Models for Heterogeneous Multicore Systems

    DTIC Science & Technology

    2011-08-08

    Badia, F.D. Igual, J. Labarta, R. Mayo and E.S. Quintana- Orti . “An extension of the StarSs Programming Model for Platforms with Multiple GPUs...R. Mayo, J.M. Perez, J. Planas, E.S. Quintana- Orti . “A Proposal to Extend the OpenMP Tasking Model for Heterogeneous Architectures ” LNCS Vol. 5568

  14. 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.

  15. A novel extended architecture with 4 6·6 4 topology based on mixed-valence Wells-Dawson arsenotungstate and mixed-ligand Cu(I) units

    NASA Astrophysics Data System (ADS)

    Tong, Ruizhan; Ren, Xiaoyu; Li, Zuoxi; Liu, Bin; Hu, Huaiming; Xue, Ganglin; Fu, Feng; Wang, Jiwu

    2010-09-01

    A novel inorganic-organic hybrid compound based on mixed-valence Wells-Dawson arsenotungstate and mixed-ligand Cu(I) units, Cu 8I(imi) 4(bpy) 6(H 2O)[As 2VW 2VW 16VlO 62]·2H 2O ( 1) (bpy=4,4'-bipydine; imi=imidazole), has been hydrothermally synthesized and characterized by elemental analysis, IR spectroscopy, thermal gravimetric analysis, luminescent spectrum and single crystal X-ray diffraction. Single-crystal X-ray diffraction revealed that four terminal and three bridging oxygen atoms of the Wells-Dawson cluster are coordinated to Cu(I) ions and form an unprecedented hepta-supporting polyoxometalate. The functionalized arsenotungstates are further connected by two kinds of tridentate linkers, Imi-Cu-(bpy)-Cu-(bpy)-Cu-(bpy)-Cu-Imi and Imi-Cu-(bpy)-Cu-(bpy)-Cu-H 2O, to construct a 3D framework with 4 6·6 4 topology. The hybrid material has an intense emission at about 397 nm.

  16. Crystal structure and carrier transport properties of a new 3D mixed-valence Cu(I)-Cu(II) coordination polymer including pyrrolidine dithiocarbamate ligand.

    PubMed

    Okubo, Takashi; Tanaka, Naoya; Kim, Kyung Ho; Anma, Haruho; Seki, Shu; Saeki, Akinori; Maekawa, Masahiko; Kuroda-Sowa, Takayoshi

    2011-03-14

    A novel mixed-valence Cu(i)-Cu(ii) coordination polymer having an infinite three-dimensional (3D) structure, {[Cu(I)(4)Cu(II)(2)Br(4)(Pyr-dtc)(4)]·CHCl(3)}(n) (1) (Pyr-dtc(-) = pyrrolidine dithiocarbamate), has been prepared and structurally characterized via X-ray diffraction. This complex consists of 1D Cu(i)-Br chains and bridging mononuclear copper(ii) units of Cu(II)(Pyr-dtc)(2), which form an infinite 3D network. A magnetic study indicates that this complex includes copper(ii) ions exhibiting a weak antiferromagnetic interaction (θ = -0.086 K) between the unpaired electrons of the copper(ii) ions present in the diamagnetic Cu(i)-Br chains. The carrier transport properties of 1 are investigated using an impedance spectroscopy technique and flash-photolysis time-resolved microwave conductivity measurement (FP-TRMC). The impedance spectroscopy reveals that this complex exhibits intriguing semiconducting properties at a small activation energy (E(a) = 0.29 eV (bulk)). The sum of the mobilities of the negative and positive carriers estimated via FP-TRMC is Σμ∼ 0.4 cm(2) V(-1) s(-1).

  17. 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.

  18. Optical properties of Eu(2+) /Eu(3+) mixed valence phosphor Ca2 SiO2 F2 :Eu(2+) /Eu(3).

    PubMed

    Xie, Mubiao; Zhu, Guoxian; Pan, Rongkai; Xie, Wei

    2017-04-19

    The Eu(2+) /Eu(3+) mixed valence phosphor Ca2 SiO2 F2 :Eu(2+) /Eu(3+) was prepared using a solid-state reaction synthesis method in a CO atmosphere, and the optical properties were investigated. The spectroscopic properties revealed that Ca(2+) ions were occupied by both Eu(2+) and Eu(3+) ions in Ca2 SiO2 F2 , and both ions were able to generate their characteristic emissions. A broad 5d → 4f Eu(2+) band at ~470 nm and narrow 4f → 4f Eu(3+) peaks upon excitation with n-UV light were observed. The ratio between Eu(2+) and Eu(3+) emissions changed regularly, and the relative intensity of the red component from Eu(3+) became systematically stronger with increasing overall Eu content. As a result, the emission color of these phosphors can be tunable from blue to pink under n-UV light excitation. Copyright © 2017 John Wiley & Sons, Ltd.

  19. In situ site-selective transition metal K-edge XAS: a powerful probe of the transformation of mixed-valence compounds.

    PubMed

    Bordage, Amélie; Trannoy, Virgile; Proux, Olivier; Vitoux, Hugo; Moulin, Robinson; Bleuzen, Anne

    2015-07-14

    We present herein the first in situ site-selective XAS experiment performed on a proof-of-principle transformation of a mixed-valence compound: the calcination of the K0.1Co(II)4[Co(III)(CN)6]2.7·20H2O Prussian Blue analogue (containing Co(2+) and Co(3+) ions in two different Oh sites) into Co3O4 (containing Co(2+) ions in a Td site and Co(3+) in an Oh site). By recording the Co K-edge X-ray absorption spectra using a spectrometer aligned at the Co Kβ1,3 emission line, the evolution of each species was singly monitored from 20 °C up to the oxide formation. The experimental spectrum of the Co(2+)(Td) and Co(3+) (Oh) species in Co3O4 is reported for the first time. Our results demonstrate the possibilities offered by site-selective XAS for the investigation of chemical transformations and the study of materials under working conditions whenever the chemical element of interest is present in several states and/or sites.

  20. Comment on ``Spin- and charge-ordering in oxygen-vacancy-ordered mixed-valence Sr4Fe4O11 ''

    NASA Astrophysics Data System (ADS)

    Adler, P.

    2008-04-01

    In a recent paper, Vidya [Phys. Rev. B 74, 054422 (2006)] investigated the structural, electronic, and magnetic properties of mixed-valence Sr4Fe4O11 by spin-polarized electronic-structure calculations. The crystal structure of this oxygen-vacancy-ordered perovskite contains square pyramidal Fe(1)s and distorted octahedral Fe(2)o sites. Only one of the sublattices is magnetically ordered below TN˜230K . Vidya claimed that their calculations unambiguously show that the formal Fe3+ ions reside in the square pyramidal and the Fe4+ ions in the octahedral sites, in contrast to the previous assignment by Hodges [J. Solid State Chem. 151, 190 (2000)]. In addition, Vidya implied that rather the Fe4+ than the Fe3+ sublattice is magnetically ordered. In this Comment, it is pointed out that the structural and Mössbauer data clearly favor the assignment of Hodges and are in disagreement with the results of Vidya The Mössbauer spectra evidence that it is the Fe3+ sublattice which is magnetically ordered.

  1. 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 .

  2. A distributed scheduling algorithm for heterogeneous real-time systems

    NASA Technical Reports Server (NTRS)

    Zeineldine, Osman; El-Toweissy, Mohamed; Mukkamala, Ravi

    1991-01-01

    Much of the previous work on load balancing and scheduling in distributed environments was concerned with homogeneous systems and homogeneous loads. Several of the results indicated that random policies are as effective as other more complex load allocation policies. The effects of heterogeneity on scheduling algorithms for hard real time systems is examined. A distributed scheduler specifically to handle heterogeneities in both nodes and node traffic is proposed. The performance of the algorithm is measured in terms of the percentage of jobs discarded. While a random task allocation is very sensitive to heterogeneities, the algorithm is shown to be robust to such non-uniformities in system components and load.

  3. Photon scattering effects in heterogeneous scintillator systems

    SciTech Connect

    Ross, H.H.

    1989-01-01

    This paper describes a new experimental approach that reveals the individual contributions of sample geometry and scattering phenomena in heterogeneous flow-cell detectors. The experimental detector responses obtained using scintillating polystyrene beads with optically smooth surfaces are compared with those obtained using similar beads with highly diffuse surfaces. These comparisons are carried out for both alpha- and beta-emitting nuclides. The experimental detection efficiencies are compared to Monte Carlo simulations of the detection process. Also, a new technique will be described for the fabrication of scintillating beads. 7 refs., 8 figs., 2 tabs.

  4. Valence Change Driven by Constituent Element Substitution in the Mixed-Valence Quasicrystal and Approximant Au-Al-Yb

    NASA Astrophysics Data System (ADS)

    Matsukawa, Shuya; Tanaka, Katsumasa; Nakayama, Mika; Deguchi, Kazuhiko; Imura, Keiichiro; Takakura, Hiroyuki; Kashimoto, Shiro; Ishimasa, Tsutomu; Sato, Noriaki K.

    2014-03-01

    Quantum criticality has been considered to be specific to crystalline materials such as heavy fermions. Very recently, however, the Tsai-type quasicrystal Au51Al34Yb15 has been reported to show unusual quantum critical behavior. To obtain a deeper understanding of this new material, we have searched for other Tsai-type cluster materials. Here, we report that the metal alloys Au44Ga41Yb15 and Ag47Ga38Yb15 are members of the 1/1 approximant to the Tsai-type quasicrystal and that both possess no localized magnetic moment. We suggest that the Au-Al-Yb system is located near the border of the divalent and trivalent states of the Yb ion; we also discuss a possible origin of the disappearance of magnetism, associated with the valence change, by the substitution of the constituent elements.

  5. Neutral and cationic V(IV)/V(V) mixed-valence alkoxo-polyoxovanadium clusters [V6O7(OR)12]n+ (R = -CH3, -C2H5): structural, cyclovoltammetric and IR-spectroscopic investigations on mixed valency in a hexanuclear core.

    PubMed

    Daniel, Charles; Hartl, Hans

    2005-10-12

    The alkoxo-polyoxovanadium clusters [V6O7(OR)12]n+ (R = -CH3, -C2H5) are fully alkylated polyoxometalate derivatives comprising a hexavanadate core with the vanadium ions organized in an octahedral fashion, a classic isopolyoxometalate structure (Lindqvist) which as an entity is not known for vanadium. The clusters are highly redox-active compounds, displaying a large number of thermodynamically stable redox isomers of which the chemical syntheses and structural characterization of the neutral and cationic V(IV)/V(V) mixed-valence species [V(IV)(4-n)V(V)(2+n)O7(OR)12]n+ [SbCl6]n (R = -CH3, n = 0, 1; R = -C2H5, n = 0, 1, 2) are presented here. Neutral and positively charged clusters remain exceptional in the field of polyoxometalate chemistry. Results obtained from cyclic voltammetry, infrared spectroscopy, and from valence sum calculations conducted on X-ray structural data classify these clusters as class II mixed-valence compounds. Their highly symmetrical molecular structures make them particularly interesting as model compounds for the investigation of intervalence charge transfer and electron delocalization in the hexanuclear core. Furthermore, the large number of isostructural redox isomers affords a high variability in d-electron content. Accordingly, a dependency could clearly be established between the extent of electron delocalization and the V(IV)/V(V) ratio in a cluster species. A further interesting observation concerns the neutral ethoxo compound [V(IV)4V(V)2O7(OC2H5)12] (3) which exhibits a crystallographic phase transition accompanied by the conversion from a structure at 173 K with fully localized valencies to a room-temperature modification displaying complete d-electron delocalization.

  6. Dual emission and excited-state mixed-valence in a quasi-symmetric dinuclear Ru-Ru complex.

    PubMed

    Kreitner, Christoph; Grabolle, Markus; Resch-Genger, Ute; Heinze, Katja

    2014-12-15

    The synthesis and characterization of the new dinuclear dipeptide [(EtOOC-tpy)Ru(tpy-NHCO-tpy)Ru(tpy-NHCOCH3)](4+) 3(4+) of the bis(terpyridine)ruthenium amino acid [(HOOC-tpy)Ru(tpy-NH2)](2+) 1(2+) are described, and the properties of the dipeptide are compared to those of the mononuclear complex [(EtOOC-tpy)Ru(tpy-NHCOCH3)](2+) 4(2+) carrying the same functional groups. 3(4+) is designed to serve a high electronic similarity of the two ruthenium sites despite the intrinsic asymmetry arising from the amide bridge. This is confirmed via UV-vis absorption and NMR spectroscopy as well as cyclic voltammetry. 4(2+) and 3(4+) are emissive at room temperature, as expected. Moreover, 3(4+) exhibits dual emission from two different triplet states with different energies and lifetimes at room temperature. This is ascribed to the presence of a unique thermal equilibrium between coexisting [Ru(II)(tpy-NHCO-tpy(·-))Ru(III)] and [Ru(III)(tpy-NHCO-tpy(·-))Ru(II)] states leading to an unprecedented excited-state Ru(II)Ru(III) mixed-valent system via the radical anion bridge tpy-NHCO-tpy(·-). The mixed-valent cation 3(5+), on the other hand, shows no measurable interaction of the Ru(II)Ru(III) centers via the neutral bridge tpy-NHCO-tpy (Robin-Day class I). Reduction of 3(4+) to the radical cation 3(3+) by decamethylcobaltocene is bridge-centered as evidenced by rapid-freeze electron paramagnetic resonance spectroscopy. Interestingly, all attempts to observe 3(3+) via NMR and UV-vis absorption spectroscopy only led to the detection of the diamagnetic complex 3-H(3+) in which the bridging amide is deprotonated. Hence 3-H(3+) (and 4-H(+)) appear to reduce protons to dihydrogen. The ease of single and double deprotonation of 4(2+) and 3(4+) to 4-H(+), 3-H(3+), and 3-2H(2+) was demonstrated using a strong base and was studied using NMR and UV-vis absorption spectroscopies. The equilibrating excited triplet states of 3(4+) are reductively quenched by N,N-dimethylaniline assisted by

  7. Coordination and metalation bifunctionality of Cu with 5,10,15,20-tetra(4-pyridyl)porphyrin: toward a mixed-valence two-dimensional coordination network.

    PubMed

    Li, Yang; Xiao, Jie; Shubina, Tatyana E; Chen, Min; Shi, Ziliang; Schmid, Martin; Steinrück, Hans-Peter; Gottfried, J Michael; Lin, Nian

    2012-04-11

    We investigated the coordination self-assembly and metalation reaction of Cu with 5,10,15,20-tetra(4-pyridyl)porphyrin (2HTPyP) on a Au(111) surface by means of scanning tunneling microscopy, X-ray photoelectron spectroscopy, and density functional theory calculations. 2HTPyP was found to interact with Cu through both the peripheral pyridyl groups and the porphyrin core. Pairs of pyridyl groups from neighboring molecules coordinate Cu(0) atoms, which leads to the formation of a supramolecular metal-organic coordination network. The network formation occurs at room temperature; annealing at 450 K enhances the process. The interaction of Cu with the porphyrin core is more complex. At room temperature, formation of an initial complex Cu(0)-2HTPyP is observed. Annealing at 450 K activates an intramolecular redox reaction, by which the coordinated Cu(0) is oxidized to Cu(II) and the complex Cu(II)TPyP is formed. The coordination network consists then of Cu(II) complexes linked by Cu(0) atoms; that is, it represents a mixed-valence two-dimensional coordination network consisting of an ordered array of Cu(II) and Cu(0) centers. Above 520 K, the network degrades and the Cu atoms in the linking positions diffuse into the substrate, while the Cu(II)TPyP complexes form a close-packed structure that is stabilized by weak intermolecular interactions. Density functional theory investigations show that the reaction with Cu(0) proceeds via formation of an initial complex between metal atom and porphyrin followed by formation of Cu(II) porphyrin within the course of the reaction. The activation barrier of the rate limiting step was found to be 24-37 kcal mol(-1) depending on the method used. In addition, linear coordination of a Cu atom by two CuTPyP molecules is favorable according to gas-phase calculations. © 2012 American Chemical Society

  8. [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.

  9. 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.

  10. Photodamage of a Mn(III/IV)-oxo mixed-valence compound and photosystem II: evidence that a high-valent manganese species is responsible for UV-induced photodamage of the oxygen-evolving complex in photosystem II.

    PubMed

    Wei, Zi; Cady, Clyde W; Brudvig, Gary W; Hou, Harvey J M

    2011-01-01

    The Mn cluster in photosystem II (PS II) is believed to play an important role in the UV photoinhibition of green plants, but the mechanism is still not clear at a molecular level. In this work, the photochemical stability of [Mn(III)(O)(2)Mn(IV)(H(2)O)(2)(Terpy)(2)](NO(3))(3) (Terpy=2,2':6',2''-terpyridine), designated as Mn-oxo mixed-valence dimer, a well characterized functional model of the oxygen-evolving complex in PS II, was examined in aqueous solution by exposing the complex to excess light irradiation at six different wavelengths in the range of 250 to 700 nm. The photodamage of the Mn-oxo mixed-valence dimer was confirmed by the decrease of its oxygen-evolution activity measured in the presence of the chemical oxidant oxone. Ultraviolet light irradiation induced a new absorption peak at around 400-440 nm of the Mn-oxo mixed-valence dimer. Visible light did not have the same effect on the Mn-oxo mixed-valence dimer. We speculate that the spectral change may be caused by conversion of the Mn(III)O(2)Mn(IV) dimer into a new structure--Mn(IV)O(2)Mn(IV). In the processes, the appearance of a 514 nm fluorescence peak was observed in the solution and may be linked to the hydration or protonation of Terpy ligand in the Mn-oxo dimer. In comparing the response of the PS II functional model compound and the PS II complex to excess light radiation, our results support the idea that UV photoinhibition is triggered at the Mn(4)Ca center of the oxygen-evolution complex in PS II by forming a modified structure, possibly a Mn(IV) species, and that the reaction of Mn ions is likely the initial step.

  11. Analysis of the excitation profiles of Raman bands of linear-chain mixed-valence complexes. The geometry of [Pt(en) 2][Pt(en) 2Br 2]Br 4 in the intervalence state

    NASA Astrophysics Data System (ADS)

    Clark, Robin J. H.; Dines, Trevor J.

    1991-10-01

    Calculations of the resonance Raman excitation profiles for the ν 1 band and its overtones have been performed for the linear- chain mixed-valence platinum complex [Pt(en) 2Br 2]Br 4. It is found that the Pt IV length increases by 0.075 Å in the intervalence state. A satisfactory fit to the excitation profiles requires the inclusion of a second excited state at 16500 cm -1, which we have assigned to Br→Pt IV charge transfer.

  12. 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

    2008-07-07

    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.

  13. Macrophage heterogeneity and renin-angiotensin system disorders.

    PubMed

    Wright, Mark D; Binger, Katrina J

    2017-04-01

    Macrophages are heterogeneous innate immune cells which are important in both the maintenance of tissue homeostasis and its disruption, by promoting tissue inflammation and fibrosis. The renin-angiotensin system is central to the pathophysiology of a large suite of diseases, which are driven in part by large amounts of tissue inflammation and fibrosis. Here, we review recent advances in understanding macrophage heterogeneity in origin and function, and how these may lead to new insights into the pathogenesis of these chronic diseases.

  14. 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.

  15. 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.

  16. Model and method for optimizing heterogeneous systems

    NASA Astrophysics Data System (ADS)

    Antamoshkin, O. A.; Antamoshkina, O. A.; Zelenkov, P. V.; Kovalev, I. V.

    2016-11-01

    Methodology of distributed computing performance boost by reduction of delays number is proposed. Concept of n-dimentional requirements triangle is introduced. Dynamic mathematical model of resource use in distributed computing systems is described.

  17. 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.

  18. Excited-state electronic coupling and photoinduced multiple electron transfer in two related ligand-bridged hexanuclear mixed-valence compounds.

    PubMed

    Pfennig, Brian W; Mordas, Carolyn J; McCloskey, Alex; Lockard, Jenny V; Salmon, Patty M; Cohen, Jamie L; Watson, David F; Bocarsly, Andrew B

    2002-08-26

    The synthesis, characterization, electrochemical, photophysical, and photochemical properties of two hexanuclear mixed-valence compounds are reported. Each supramolecular species consists of two cyano-bridged [(NC)(5)Fe(II)-CN-Pt(IV)(NH(3))(3)L-NC-Fe(II)(CN)(5)] triads that are linked to each other through a Pt(IV)-L-Pt(IV) bridge, where L = 4,4'-dipyridyl (bpy) or 3,3'-dimethyl-4,4'-dipyridyl (dmb). The major difference between the two compounds is the electronic nature of the bridging ligand between the two Pt atoms. Both species exhibit a broad Fe(II) --> Pt(IV) intervalent (IT) absorption band at 421 nm with an oscillator strength that is approximately four times that for [(NC)(5)Fe(II)-CN-Pt(IV)(NH(3))(5)] and twice that for [(NC)(5)Fe(II)-CN-Pt(IV)(NH(3))(4)-NC-Fe(II)(CN)(5)].(4-) When L = bpy, the resonance Raman spectrum obtained by irradiating the IT band at 488 nm exhibits several dipyridyl ring modes at 1604, 1291, and 1234 cm(-1) which are not present in the spectrum when L = dmb. In addition, femtosecond pump-probe spectroscopy performed at 400 nm yields a transient bleach of the IT absorption band with a single exponential decay of 3.5 ps for L = bpy, compared with only 1.8 ps for L = dmb and 2.1 ps for [(NC)(5)Fe(II)-CN-Pt(IV)(NH(3))(4)-NC-Fe(II)(CN)(5)].(4-) Last, prolonged irradiation of the complexes at 488 nm leads to the formation of 4 equiv of ferricyanide with a quantum efficiency of 0.0014 for L = bpy and 0.0011 for L = dmb. The transient absorption, resonance Raman, and photochemical data suggest that the degree of excited electronic coupling in these compounds is tunable by changing the electronic nature of the Pt-L-Pt bridging ligand.

  19. 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

  20. 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

    2015-10-07

    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

  1. 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

  2. Structure, magnetism, and theoretical study of a mixed-valence Co(II)3Co(III)4 heptanuclear wheel: lack of SMM behavior despite negative magnetic anisotropy.

    PubMed

    Chibotaru, Liviu F; Ungur, Liviu; Aronica, Christophe; Elmoll, Hani; Pilet, Guillaume; Luneau, Dominique

    2008-09-17

    A mixed-valence Co(II)/Co(III) heptanuclear wheel [Co(II)3Co(III)4(L)6(MeO)6] (LH2 = 1,1,1-trifluoro-7-hydroxy-4-methyl-5-aza-hept-3-en-2-one) has been synthesized and its crystal structure determined using single-crystal X-ray diffraction. The valence state of each cobalt ion was established by bond valence sum calculations. Studies of the temperature dependence of the magnetic susceptibility and the field dependence of the magnetization evidence ferromagnetic interactions within the compound. In order to understand the magnetic properties of this Co7 wheel, we performed ab initio calculations for each cobalt fragment at the CASSCF/CASPT2 level, including spin-orbit coupling effects within the SO-RASSI approach. The four Co(III) ions were found to be diamagnetic and to give a significant temperature-independent paramagnetic contribution to the susceptibility. The spin-orbit coupling on the three Co(II) sites leads to separations of approximately 200 cm(-1) between the ground and excited Kramers doublets, placing the Co7 wheel into a weak-exchange limit in which the lowest electronic states are adequately described by the anisotropic exchange interaction between the lowest Kramers doublets on Co(II) sites. Simulation of the exchange interaction was done within the Lines model, keeping the fully ab initio treatment of magnetic anisotropy effects on individual cobalt fragments using a recently developed methodology. A good description of the susceptibility and magnetization was obtained for nearest-neighbor (J1) and next-nearest-neighbor (J2) exchange parameters (1.5 and 5.5 cm(-1), respectively). The strong ferromagnetic interaction between distant cobalt ions arises as a result of low electron-promotion energies in the exchange bridges containing Co(III) ions. The calculations showed a large value of the magnetization along the main magnetic axis (10.1 mu(B)), which is a combined effect of the ferromagnetic exchange interaction and negative magnetic anisotropy on

  3. 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.

  4. 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.

  5. Reliable Neuronal Systems: The Importance of Heterogeneity

    PubMed Central

    Lengler, Johannes; Jug, Florian; Steger, Angelika

    2013-01-01

    For every engineer it goes without saying: in order to build a reliable system we need components that consistently behave precisely as they should. It is also well known that neurons, the building blocks of brains, do not satisfy this constraint. Even neurons of the same type come with huge variances in their properties and these properties also vary over time. Synapses, the connections between neurons, are highly unreliable in forwarding signals. In this paper we argue that both these fact add variance to neuronal processes, and that this variance is not a handicap of neural systems, but that instead predictable and reliable functional behavior of neural systems depends crucially on this variability. In particular, we show that higher variance allows a recurrently connected neural population to react more sensitively to incoming signals, and processes them faster and more energy efficient. This, for example, challenges the general assumption that the intrinsic variability of neurons in the brain is a defect that has to be overcome by synaptic plasticity in the process of learning. PMID:24324621

  6. 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.

  7. An effective cache algorithm for heterogeneous storage systems.

    PubMed

    Li, Yong; Feng, Dan; Shi, Zhan

    2013-01-01

    Modern storage environment is commonly composed of heterogeneous storage devices. However, traditional cache algorithms exhibit performance degradation in heterogeneous storage systems because they were not designed to work with the diverse performance characteristics. In this paper, we present a new cache algorithm called HCM for heterogeneous storage systems. The HCM algorithm partitions the cache among the disks and adopts an effective scheme to balance the work across the disks. Furthermore, it applies benefit-cost analysis to choose the best allocation of cache block to improve the performance. Conducting simulations with a variety of traces and a wide range of cache size, our experiments show that HCM significantly outperforms the existing state-of-the-art storage-aware cache algorithms.

  8. Distributed heterogeneous inspecting system and its middleware-based solution.

    PubMed

    Huang, Li-can; Wu, Zhao-hui; Pan, Yun-he

    2003-01-01

    There are many cases when an organization needs to monitor the data and operations of its supervised departments, especially those departments which are not owned by this organization and are managed by their own information systems. Distributed Heterogeneous Inspecting System (DHIS) is the system an organization uses to monitor its supervised departments by inspecting their information systems. In DHIS, the inspected systems are generally distributed, heterogeneous, and constructed by different companies. DHIS has three key processes-abstracting core data sets and core operation sets, collecting these sets, and inspecting these collected sets. In this paper, we present the concept and mathematical definition of DHIS, a metadata method for solving the interoperability, a security strategy for data transferring, and a middleware-based solution of DHIS. We also describe an example of the inspecting system at WENZHOU custom.

  9. 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.

  10. Purple mixed-valence Cu{sub A} center in nitrous-oxide reductase: EPR of the copper-63-, copper-65-, and both copper-65- and [{sup 15}N] histidine-enriched enzyme and a molecular orbital interpretation

    SciTech Connect

    Neese, F.; Kroneck, P.M.H.; Zumft, W.G.; Antholine, W.E.

    1996-09-11

    EPR spectra for the purple mixed-valence [Cu{sup 1.5+}...Cu{sup 1.5+}], S = 1/2, site (Cu{sub A}) in nitrous-oxide reductase (N{sub 2}OR) were obtained after insertion of either {sup 63}Cu or {sup 65}Cu or both {sup 65}Cu and [{sup 15}N]histidine. The spectrum of {sup 65}Cu- and [{sup 15}N]histidine-enriched N{sub 2}OR improved the resolution of the Cu hyperfine lines, but no lines from nitrogen and proton couplings were resolved. The Cu hyperfine parameters obtained by a theory analogous to that of Maki and McGarvey were indicative of a highly covalent Cu site. The total Cu character (Cu{sub A1} + Cu{sub A2}) in the ground state wave function required to describe the spin density distribution was 31-37% compared to 41% for type-1 Cu in plastocyanin. This value does not completely account for the reduction of g{sub max} from 2.23 of type-1 Cu in plastocyanin to 2.18 of Cu{sub A}. Remaining discrepancies were discussed in terms of different alignments of the principal axes for the hypothetical monomeric Cu{sup A1} and Cu{sub A2} in [Cu{sup 1.5+}...Cu{sup 1.5+}]. This effect appeared in the simulations of the EPR spectra as a noncoincidence between the Cu hyperfine and g principal axis systems. The g-value analysis of Cu{sub A} predicts an electric dipole forbidden absorption band in the near-infrared region. Based on X-ray structural data of Cu{sub A} in cytochrome c oxidase, iterative extended Hueckel and UHF-INDO/S calculations on a sulfur-bridged [(NH{sub 3})Cu{sup 1.5+}(SCH{sub 3}){sub 2}Cu{sup 1.5+}(NH{sub 3})]{sup +} core were used to interpret the EPR results. 76 refs., 7 figs., 3 tabs.

  11. 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…

  12. 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…

  13. BEHAVIOR OF WATER IN CERTAIN HETEROGENEOUS SYSTEMS

    PubMed Central

    Osterhout, W. J. V.; Murray, J. W.

    1940-01-01

    In various models designed to imitate living cells the surface of the protoplasm is represented by guaiacol which acts in some respects like certain protoplasmic surfaces. The behavior of water in these models presents interesting features and if these occur in vivo, as appears possible, they may help to explain some of the puzzling aspects of water relations in the living organism. When sufficient trichloroacetic acid is added to a two-phase system of water and guaiacol the two phases fuse into one. The effect of the acid is due to its attraction for water and for guaiacol. This is shown by the following facts. During the addition of the acid the mole fraction of water in the guaiacol phase increases but the activity of water in the guaiacol phase falls off. The activity coefficient of water may fall to less than one twelfth the value it had before acid was added. The behavior of guaiacol presents a similar picture. During the addition of acid the mole fraction of guaiacol in the aqueous phase increases but the activity of the guaiacol in the aqueous phase presumably decreases. Its activity coefficient calculated on this basis may fall to about one ninth of the value it had before the acid was added. Somewhat similar results are obtained when acetone is substituted for trichloroacetic acid or when ethanol is substituted for trichloroacetic acid and ethylene chloride for guaiacol. As trichloroacetic acid increases the mutual solubility of guaiacol and water we find that guaiacol saturated with water and having a high vapor pressure of water can take up water from an aqueous solution of trichloroacetic acid with a low vapor pressure of water: acid passes from the aqueous to the guaiacol phase, thus raising the vapor pressure of water in the aqueous phase and lowering it in the guaiacol phase. Diffusion experiments present some interesting features. When an aqueous solution, A, of trichloroacetic acid is separated by a layer of guaiacol, B, from distilled water, C

  14. An FPGA-based heterogeneous image fusion system design method

    NASA Astrophysics Data System (ADS)

    Song, Le; Lin, Yu-chi; Chen, Yan-hua; Zhao, Mei-rong

    2011-08-01

    Taking the advantages of FPGA's low cost and compact structure, an FPGA-based heterogeneous image fusion platform is established in this study. Altera's Cyclone IV series FPGA is adopted as the core processor of the platform, and the visible light CCD camera and infrared thermal imager are used as the image-capturing device in order to obtain dualchannel heterogeneous video images. Tailor-made image fusion algorithms such as gray-scale weighted averaging, maximum selection and minimum selection methods are analyzed and compared. VHDL language and the synchronous design method are utilized to perform a reliable RTL-level description. Altera's Quartus II 9.0 software is applied to simulate and implement the algorithm modules. The contrast experiments of various fusion algorithms show that, preferably image quality of the heterogeneous image fusion can be obtained on top of the proposed system. The applied range of the different fusion algorithms is also discussed.

  15. 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

  16. Spectroscopic studies of oxo-centered, carboxylate-bridged, trinuclear mixed-valence iron (ІІІ, ІІІ, ІІ) complexes with aromatic hydroxycarboxylic acids

    NASA Astrophysics Data System (ADS)

    Singh, Atresh Kumar; Singh, Alok Kumar

    2013-08-01

    New type of oxo-centered, carboxylate-bridged, trinuclear, mixed-valence iron complexes of the general formula [Fe3O(OOCR)3(OOCR*)3L3] (where R = C13H27 or C15H31 and R* = C6H4(OH), (R'); C6H5CH(OH), (R″) or (C6H5)2C(OH), (R) and L = Methanol) were synthesized by the reaction of [Fe3O(OOCCH3)6(H2O)3] with straight chain carboxylic acids and aromatic hydroxycarboxylic acids. These were characterized by elemental analyses, spectral (electronic, infrared, Mössbauer, FAB mass and powder XRD) studies, conductance and magnetic susceptibility measurements. Infrared spectra suggested bidentate and bridging mode of coordination of both the carboxylate and hydroxycarboxylate anions along with Fe3O vibrations in the complexes. Mössbauer parameters indicated the presence of high-spin Fe(ІІ) (S = 2) and high-spin Fe(ІІІ) (S = 5/2) centers in the complexes, confirming the valence-localized type of species. An intervalence-transfer band observed at 13,690-13,850 cm-1 range in the room-temperature electronic spectra of the complexes also suggested the complexes containing iron in mixed-valence state. Trinuclear nature of the complexes was confirmed by their FAB mass spectra. Magnetic moment values displayed octahedral geometry around each iron in the complexes and a net anti-ferromagnetic exchange coupling via μ-oxo atom related to mixed-valence pairs. A plausible structure for these complexes has been established on the basis of spectra and magnetic moment data.

  17. Modeling of hydrodynamics of water-methane heterogeneous system

    NASA Astrophysics Data System (ADS)

    Tsvetova, Elena A.

    2015-11-01

    To study the behavior of heterogeneous methane-water system, a mathematical model describing the joint processes of hydrodynamics, transport, and transformation of methane in a deep freshwater body is used. There are three phases of methane in the system: solid (hydrate), gaseous (bubbles) and dissolved in water. We discuss the physical origin of phase transitions in the specific conditions of Lake Baikal and possible mathematical formulations of problems. Some preliminary results of calculations are presented.

  18. Influence of extrinsic factors on electron transfer in a mixed-valence Fe(2+)/Fe(3+) complex: experimental results and theoretical considerations.

    PubMed

    Achim, C; Bominaar, E L; Staples, R J; Münck, E; Holm, R H

    2001-08-13

    The crystal structure of the mixed-valence complex (NEt(4))[Fe(2)(salmp)(2)].xMeCN(crystal) (x = 2,3) [1].xMeCN(crystal) was determined at temperatures between 153 and 293 K. The complex shows distinct Fe(2+) and Fe(3+) sites over this temperature interval. Variable temperature Mössbauer spectra confirm the valence-localized character of the complex. In contrast, spectroscopic investigation of powder samples generated from [1].xMeCN(crystal) indicate the presence of a valence-averaged component at temperatures above 150 K. To elucidate this apparent contradiction we have conducted a variable-temperature Mössbauer investigation of different forms of 1, including [1].xMeCN(crystal), [1].2DMF(crystal), [1].yMeCN(powder), and solution samples of 1 in acetonitrile. The low-temperature Mössbauer spectra of all forms are virtually identical and confirm the valence-localized nature of the S = (9)/(2) ground state. The high-temperature spectra reveal a subtle control of electron hopping by the environment of the complexes. Thus, [1].xMeCN(crystal) has valence-localized spectra at all explored temperatures, [1].2DMF(crystal) exhibits a complete collapse into a valence-averaged spectrum over a narrow temperature range, the powder exhibits partial valence averaging over a broad temperature interval, and the solution sample shows at 210 K the presence of a valence-averaged component in a minor proportion. The spectral transformations are characterized by a coexistence of valence-localized and valence-averaged spectral components. This phenomenon cannot be explained by intramolecular electron hopping between the valence-localized states Fe(A)(2+)Fe(B)(3+) and Fe(A)(3+)Fe(B)(2+) in a homogeneous ensemble of complexes, but requires relaxation processes involving at least three distinguishable states of the molecular anion. Hopping rates for [1].2DMF(crystal) and [1].yMeCN(powder) have been determined from spectral simulations, based on stochastic line shape theory. Analysis of

  19. Mechanistic aspects of the chemistry of mononuclear Cr(III) complexes with pendant-arm macrocyclic ligands and formation of discrete Cr(III)/Fe(II) and Cr(III)/Fe(II)/Co(III) cyano-bridged mixed valence compounds.

    PubMed

    Basallote, Manuel G; Bernhardt, Paul V; Calvet, Teresa; Castillo, Carmen E; Font-Bardia, Mercè; Martínez, Manuel; Rodríguez, Carlos

    2009-11-21

    The kinetics and mechanism of the redox reaction between [Fe(II)(CN)(6)](4-) and the macrocyclic ligand complex [CrClL(15)](2+) (L(15) = 6-methyl-1,4,8,12-tetraazacyclopentadecane-6-amine) has been studied at different pH values. In acidic solution, the expected redox process occurs with no formation of any of the possible Cr(III)/Fe(II) mixed valence complexes, as those seen for the Co(III) species of the same family, due to the enhanced lability of the Cr(II) species formed on Fe(II) to Fe(III) oxidation. In alkaline conditions, the formation of the complex [Cr(L(15))(OH)(2)](+) takes place as an initial step that precedes a simple substitution process producing the expected cyano-bridged Cr(III)/Fe(II) complex. In this species the potentially pentadentate ligand, L(15), has a tetradentate coordination mode with a protonated exocyclic primary amine group and the redox potential is shifted to more negative values, thus disfavouring a redox driven reaction; the equivalent complex [CrCl(HL(14))(H(2)O)](3+) (L(14) = 6-methyl-1,4,8,11-tetraazacyclotetradecane-6-amine) has been prepared by the same method and characterized by X-ray crystallography. The final [Fe(II)(CN)(6)](4-) substituted complex, [{(HL(15))(OH)Cr(III)NC}Fe(II)(CN)(5)](-) shows pK(a) values of 3.8 and 7.4, as expected for the aqua and amino ligands, respectively. Its characterization indicated its Class II mixed valence character with a very intense MMCT band at 350 nm showing a much larger extinction coefficient than that observed for the Co(III) complexes of the same family. This fact is in good agreement with the much larger Cr(III)-Fe(II) (t(2g)-t(2g)) coupling through cyanide bridging ligands expected for these complexes. The fully mixed metal/valence/ligand trimetallic complex [{(HL(15))(OH)Cr(III)NC}{L(13)Co(III)NC}Fe(II)(CN)(4)](2+) has been prepared following the same procedures and the results are comparable. The final complex has the same Class II mixed valence character and its electronic

  20. New skeletal 3D polymeric inorganic cluster [W4S16Cu16Cl16]n with Cu in mixed-valence states: solid-state synthesis, crystal structure, and third-order nonlinear optical properties.

    PubMed

    Cai, Ya; Wang, Yan; Li, Yizhi; Wang, Xiaoshu; Xin, Xinquan; Liu, Caiming; Zheng, Hegen

    2005-12-12

    A new 3D polymeric inorganic cluster with Cu in mixed-valence states was synthesized by the solid-state reaction of (NH4)2WS4, S8, CuCl, and Et4NCl; S8 may be regarded as the oxidizing agent converting Cu(I) to Cu(II) and causing the polymerization of [WS4]2-. The third-order nonlinear optical (NLO) properties are determined, and the results show that the cluster exhibits both large NLO absorptive and strong refractive behaviors.

  1. Computational heterogeneity in the human mesencephalic dopamine system.

    PubMed

    D'Ardenne, Kimberlee; Lohrenz, Terry; Bartley, Krystle A; Montague, P Read

    2013-12-01

    Recent evidence in animals has indicated that the mesencephalic dopamine system is heterogeneous anatomically, molecularly, and functionally, and it has been suggested that the dopamine system comprises distinct functional systems. Identifying and characterizing these systems in humans will have widespread ramifications for understanding drug addiction and mental health disorders. Model-based studies in humans have suggested an analogous computational heterogeneity, in which dopaminergic targets in striatum encode both experience-based learning signals and counterfactual learning signals that are based on hypothetical information. We used brainstem-tailored fMRI to identify mesencephalic sources of experiential and counterfactual learning signals. Participants completed a decision-making task based on investing in markets. This sequential investment task generated experience-based learning signals, in the form of temporal difference (TD) reward prediction errors, and counterfactual learning signals, in the form of "fictive errors." Fictive errors are reinforcement learning signals based on hypothetical information about "what could have been." An additional learning signal was constructed to be relatable to a motivational salience signal. Blood oxygenation level dependent responses in regions of substantia nigra (SN) and ventral tegmental area (VTA), where dopamine neurons are located, coded for TD and fictive errors, and additionally were related to the motivational salience signal. These results are highly consistent with animal electrophysiology and provide direct evidence that human SN and VTA heterogeneously handle important reward-harvesting computations.

  2. 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.

  3. Cooperative Output Regulation of Singular Heterogeneous Multiagent Systems.

    PubMed

    Ma, Qian; Xu, Shengyuan; Lewis, Frank L; Zhang, Baoyong; Zou, Yun

    2016-06-01

    This paper investigates the cooperative output regulation problem of singular heterogeneous multiagent systems. General distributed observers are proposed for every agent obtaining the estimated state of the exosystem. The feedforward control technique and reduced-order approach are used to design distributed singular output feedback controllers and distributed normal output feedback controllers. The proposed cooperative dynamic controller is dependent on the plant parameters and the interaction topologies. A simulation example is provided to demonstrate the effectiveness of the proposed design method.

  4. Safety Analysis of Heterogeneous-Multiprocessor Control System Software

    DTIC Science & Technology

    1990-12-01

    NAVAL POSTGRADUATE SCHOOL Monterey, California LD 00 N I DTIC G OE ECTE THESIS SAFETY ANALYSIS OF HETEROGENEOUS-MULTPROCESSOR CONTROL SYSTEM SOFTWARE...NAMEOFMONIURING ORGANIZATION Naval Postgraduate School (If Applicable) Naval Postgraduae- -- School 37 _ • 6c- ADDRESS (city, state, and ZIP code) 7b. ADDRESS...partial fulfillment of the requirements for the degree of MASTER OF SCIENCE IN COMPUTER SCIENCE from the NAVAL POSTGRADUATE SCHOOL December, 1990

  5. Hierarchical Policy Model for Managing Heterogeneous Security Systems

    NASA Astrophysics Data System (ADS)

    Lee, Dong-Young; Kim, Minsoo

    2007-12-01

    The integrated security management becomes increasingly complex as security manager must take heterogeneous security systems, different networking technologies, and distributed applications into consideration. The task of managing these security systems and applications depends on various systems and vender specific issues. In this paper, we present a hierarchical policy model which are derived from the conceptual policy, and specify means to enforce this behavior. The hierarchical policy model consist of five levels which are conceptual policy level, goal-oriented policy level, target policy level, process policy level and low-level policy.

  6. 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.

  7. A novel extended architecture with 4{sup 6}.6{sup 4} topology based on mixed-valence Wells-Dawson arsenotungstate and mixed-ligand Cu(I) units

    SciTech Connect

    Tong Ruizhan; Ren Xiaoyu; Li Zuoxi; Liu Bin; Hu Huaiming; Xue Ganglin; Fu Feng; Wang Jiwu

    2010-09-15

    A novel inorganic-organic hybrid compound based on mixed-valence Wells-Dawson arsenotungstate and mixed-ligand Cu(I) units, Cu{sub 8}{sup I}(imi){sub 4}(bpy){sub 6}(H{sub 2}O)[As{sub 2}{sup V}W{sub 2}{sup V}W{sub 16}{sup Vl}O{sub 62}].2H{sub 2}O (1) (bpy=4,4'-bipydine; imi=imidazole), has been hydrothermally synthesized and characterized by elemental analysis, IR spectroscopy, thermal gravimetric analysis, luminescent spectrum and single crystal X-ray diffraction. Single-crystal X-ray diffraction revealed that four terminal and three bridging oxygen atoms of the Wells-Dawson cluster are coordinated to Cu(I) ions and form an unprecedented hepta-supporting polyoxometalate. The functionalized arsenotungstates are further connected by two kinds of tridentate linkers, Imi-Cu-(bpy)-Cu-(bpy)-Cu-(bpy)-Cu-Imi and Imi-Cu-(bpy)-Cu-(bpy)-Cu-H{sub 2}O, to construct a 3D framework with 4{sup 6}.6{sup 4} topology. The hybrid material has an intense emission at about 397 nm. - Graphical abstract: A novel organic-inorganic hybrid compound based on mixed-valence Wells-Dawson arsenotungstate and mixed-ligand Cu(I) units has been successfully synthesized. The functionalized arsenotungstate exhibits a five-connected 4{sup 6}.6{sup 4} topology network.

  8. Isovalent Ag(III) /Ag(III) , Ag(II) /Ag(II) , Mixed-Valent Ag(II) /Ag(III) , and Corrolato-Based Mixed-Valency in β,β'-Linked [Bis{corrolato-silver}](n) Complexes.

    PubMed

    Patra, Bratati; Sobottka, Sebastian; Sinha, Woormileela; Sarkar, Biprajit; Kar, Sanjib

    2017-07-28

    Mixed-valent compounds are fascinating entities that are useful as models for investigating electron-transfer reactions, and find use in a host of biologically relevant redox processes. Though the bio-relevant metal copper is well established in mixed-valent chemistry, the Ag(II) /Ag(III) mixed-valent combination of its higher congener in a molecular complex has rarely been reported before. This work reports the synthesis of a new β,β'-linked bis{corrolato-silver(III)} complex and its characterization in five different redox states. A combination of electrochemistry, spectroelectrochemistry, and DFT calculations point to the existence of a mixed-valent Ag(II) /Ag(III) and an isovalent Ag(II) /Ag(II) form. Additionally, characterization of the Ag(III) /Ag(III) form and ligand-based corrolato-centered mixed-valency is presented as well. These results thus open new avenues for bis-corrolato ligands and for mixed-valency in disilver compounds. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Network-Based Practical Consensus of Heterogeneous Nonlinear Multiagent Systems.

    PubMed

    Ding, Lei; Zheng, Wei Xing

    2016-09-07

    This paper studies network-based practical leader-following consensus problem of heterogeneous multiagent systems with Lipschitz nonlinear dynamics under both fixed and switching topologies. Considering the effect of network-induced delay, a network-based leader-following consensus protocol with heterogeneous gain matrix is proposed for each follower agent. By employing Lyapunov-Krasovskii method, a sufficient condition for designing the network-based consensus controller gain is derived such that the leader-following consensus error exponentially converges to a bounded region under a fixed topology. Correspondingly, the proposed design approach is then extended to the case of switching topology. Two numerical examples with networked Chua's circuits are given to show the efficiency of the design method proposed in this paper.

  10. Modeling heterogeneous processor scheduling for real time systems

    NASA Technical Reports Server (NTRS)

    Leathrum, J. F.; Mielke, R. R.; Stoughton, J. W.

    1994-01-01

    A new model is presented to describe dataflow algorithms implemented in a multiprocessing system. Called the resource/data flow graph (RDFG), the model explicitly represents cyclo-static processor schedules as circuits of processor arcs which reflect the order that processors execute graph nodes. The model also allows the guarantee of meeting hard real-time deadlines. When unfolded, the model identifies statically the processor schedule. The model therefore is useful for determining the throughput and latency of systems with heterogeneous processors. The applicability of the model is demonstrated using a space surveillance algorithm.

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

    PubMed

    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.

  12. 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

  13. Homogeneous vs. heterogeneous nucleation in water-dicarboxylic acid systems

    NASA Astrophysics Data System (ADS)

    Hienola, A. I.; Vehkamäki, H.; Riipinen, I.; Kulmala, M.

    2009-03-01

    Binary heterogeneous nucleation of water-succinic/glutaric/malonic/adipic acid on nanometer-sized particles is investigated within the frame of classical heterogeneous nucleation theory. Homogeneous nucleation is also included for comparison. It is found that the nucleation probabilities depend on the contact angle and on the size of the seed particles. New thermodynamical properties, such as saturation vapor pressure, density and surface tension for all the dicarboxylic acid aqueous solutions are included in the calculations. While the new surface tension and density formulations do not bring any significant difference in the computed nucleation rate for homogeneous nucleation for succinic and glutaric acids, the use of the newly derived equations for the vapor pressure decrease the acid concentrations in gas phase by 3 orders of magnitude. According to our calculations, the binary heterogeneous nucleation of succinic acid-water and glutaric acid-water - although it requires a 3-4 orders of magnitude lower vapor concentrations than the homogeneous nucleation - cannot take place under atmospheric conditions. On the other hand binary homogeneous nucleation of adipic acid-water systems might be possible under conditions occuring in upper boundary layer. However, a more detailed characterization of the interaction between the surface and the molecules of the nucleating vapor should be considered in the future.

  14. Colorectal Cancer Classification and Cell Heterogeneity: A Systems Oncology Approach.

    PubMed

    Blanco-Calvo, Moisés; Concha, Ángel; Figueroa, Angélica; Garrido, Federico; Valladares-Ayerbes, Manuel

    2015-06-15

    Colorectal cancer is a heterogeneous disease that manifests through diverse clinical scenarios. During many years, our knowledge about the variability of colorectal tumors was limited to the histopathological analysis from which generic classifications associated with different clinical expectations are derived. However, currently we are beginning to understand that under the intense pathological and clinical variability of these tumors there underlies strong genetic and biological heterogeneity. Thus, with the increasing available information of inter-tumor and intra-tumor heterogeneity, the classical pathological approach is being displaced in favor of novel molecular classifications. In the present article, we summarize the most relevant proposals of molecular classifications obtained from the analysis of colorectal tumors using powerful high throughput techniques and devices. We also discuss the role that cancer systems biology may play in the integration and interpretation of the high amount of data generated and the challenges to be addressed in the future development of precision oncology. In addition, we review the current state of implementation of these novel tools in the pathological laboratory and in clinical practice.

  15. Colorectal Cancer Classification and Cell Heterogeneity: A Systems Oncology Approach

    PubMed Central

    Blanco-Calvo, Moisés; Concha, Ángel; Figueroa, Angélica; Garrido, Federico; Valladares-Ayerbes, Manuel

    2015-01-01

    Colorectal cancer is a heterogeneous disease that manifests through diverse clinical scenarios. During many years, our knowledge about the variability of colorectal tumors was limited to the histopathological analysis from which generic classifications associated with different clinical expectations are derived. However, currently we are beginning to understand that under the intense pathological and clinical variability of these tumors there underlies strong genetic and biological heterogeneity. Thus, with the increasing available information of inter-tumor and intra-tumor heterogeneity, the classical pathological approach is being displaced in favor of novel molecular classifications. In the present article, we summarize the most relevant proposals of molecular classifications obtained from the analysis of colorectal tumors using powerful high throughput techniques and devices. We also discuss the role that cancer systems biology may play in the integration and interpretation of the high amount of data generated and the challenges to be addressed in the future development of precision oncology. In addition, we review the current state of implementation of these novel tools in the pathological laboratory and in clinical practice. PMID:26084042

  16. Heterogeneity and Context in Semantic-Web-Enabled HCLS Systems

    NASA Astrophysics Data System (ADS)

    Zimmermann, Antoine; Sahay, Ratnesh; Fox, Ronan; Polleres, Axel

    The need for semantics preserving integration of complex data has been widely recognized in the healthcare domain. While standards such as Health Level Seven (HL7) have been developed in this direction, they have mostly been applied in limited, controlled environments, still being used incoherently across countries, organizations, or hospitals. In a more mobile and global society, data and knowledge are going to be commonly exchanged between various systems at Web scale. Specialists in this domain have increasingly argued in favor of using Semantic Web technologies for modeling healthcare data in a well formalized way. This paper provides a reality check in how far current Semantic Web standards can tackle interoperability issues arising in such systems driven by the modeling of concrete use cases on exchanging clinical data and practices. Recognizing the insufficiency of standard OWL to model our scenario, we survey theoretical approaches to extend OWL by modularity and context towards handling heterogeneity in Semantic-Web-enabled health care and life sciences (HCLS) systems. We come to the conclusion that none of these approaches addresses all of our use case heterogeneity aspects in its entirety. We finally sketch paths on how better approaches could be devised by combining several existing techniques.

  17. 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.

  18. Europium mixed-valence, long-range magnetic order, and dynamic magnetic response in EuCu2(SixGe1-x)2

    SciTech Connect

    Nemkovski, Krill S.; Kozlenko, D. P.; Alekseev, Pavel A.; Mignot, J. -M.; Menushenkov, A. P.; Yaroslavtsev, A. A.; Clementyev, E. S.; Ivanov, Alexander S.; Rols, Stephane; Klobes, B.; Hermann, Rachel P.; Gribanov, A. V.

    2016-11-01

    In mixed-valence or heavy-fermion systems, the hybridization between local f orbitals and conduction band states can cause the suppression of long-range magnetic order, which competes with strong spin uctuations. Ce- and Yb-based systems have been found to exhibit fascinating physical properties (heavy-fermion superconductivity, non-Fermi-liquid states, etc.) when tuned to the vicinity of magnetic quantum critical points by use of various external control parameters (temperature, magnetic eld, chemical composition). Recently, similar effects (mixed-valence, Kondo uctuations, heavy Fermi liquid) have been reported to exist in some Eu-based compounds. Unlike Ce (Yb), Eu has a multiple electron (hole) occupancy of its 4f shell, and the magnetic Eu2+ state (4f7) has no orbital component in the usual LS coupling scheme, which can lead to a quite different and interesting physics. In the EuCu2(SixGe1-x)2 series, where the valence can be tuned by varying the Si/Ge ratio, it has been reported that a significant valence uctuation can exist even in the magnetic order regime. This paper presents a detailed study of the latter material using different microscopic probes (XANES, Mossbauer spectroscopy, elastic and inelastic neutron scattering), in which the composition dependence of the magnetic order and dynamics across the series is traced back to the change in the Eu valence state. In particular, the results support the persistence of valence uctuations into the antiferromagnetic state over a sizable composition range below the critical Si concentration xc ≈ 0:65. In conclusion, the sequence of magnetic ground states in the series is shown to re ect the evolution of the magnetic spectral response.

  19. 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.

  20. 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

  1. A uniform approach for programming distributed heterogeneous computing systems.

    PubMed

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

    2014-12-01

    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.

  2. Counterion N.M.R. in heterogeneous aqueous systems

    NASA Astrophysics Data System (ADS)

    Linse, Per; Halle, Bertil

    The molecular origin of the electric field gradient (efg) experienced by an atomic ion in a heterogeneous aqueous solution has been examined with the molecular dynamics simulation technique. A model system comparising 50 sodium ions and 1000 water molecules, spherically enclosed by a hydrophobic interface carrying 50 carboxylate groups, was simulated during 50 ps. Previously, this problem has been approached only within the continuum-solvent approximation. Our results show that the counterion efg is strongly affected by the local solvent structure and, hence cannot be adequately described in a continuum-solvent model. In particular, the so-called polarization factor, which accounts for solvent 'screening' of the efg in continuum models, was found to be highly dependent on the ionic configuration. For the counterion population analysed here, the polarization factor thus spans the entire range from no screening (corresponding to ɛ4 = 1 in an electrostatic continuum model) to complete screening (ɛr = ∞). The results of this study are relevant for the interpretation of counterion N.M.R. relaxation rates and quadrupolar line splittings from a variety of heterogeneous aqueous systems, ranging from solutions of polyelectrolytes (e.g. DNA), micelles or colloids to microemulsions and lyotropic liquid crystals.

  3. The role of heterogeneity in long-range interacting systems: From nucleation to earthquake fault systems

    NASA Astrophysics Data System (ADS)

    Silva, James Brian

    The role of heterogeneity in two long-range systems is explored with a focus on the interplay of this heterogeneity with the component system interactions. The first will be the heterogeneous Ising model with long-range interactions. Earthquake fault systems under long-range stress transfer with varying types of heterogeneity will be the second system of interest. First I will review the use of the intervention method to determine the time and place of nucleation and extend its use as an indicator for spinodal nucleation. The heterogeneous Ising model with fixed magnetic sites will then be reformulated as a dilute random field Ising model. This reformulation will allow for the application of spinodal nucleation theory to the heterogeneous Ising model by correcting the spinodal field and the critical exponent sigma describing the critical behavior of clusters in spinodal nucleation theory. The applicability of this correction is shown by simulations that determine the cluster scaling of the nucleating droplets near the spinodal. Having obtained a reasonable definition of the saddle point object describing the nucleation droplet, the density profile of the nucleating droplet is measured and deviations from homogeneous spinodal nucleation are found due to the excess amount of sparseness in the nucleating droplet due to the heterogeneity. Earthquake fault systems are then introduced and a connection is shown of two earthquake models. Heterogeneity is introduced in the form of asperities with the intent of modeling the effect of hard rocks on earthquake statistics. The asperities are observed to be a crucial element in explaining the behavior of aftershocks resulting in Omori's law. A second form of heterogeneity is introduced by coupling the Olami-Feder-Christensen model to an invasion percolation model for the purpose of modeling an earthquake fault system undergoing hydraulic fracturing. The ergodicty and event size statistics are explored in this extended model. The

  4. Conformation-determined through-bond versus through-space electronic communication in mixed-valence systems with a cross-conjugated urea bridge.

    PubMed

    Gong, Zhong-Liang; Zhong, Yu-Wu; Yao, Jiannian

    2015-01-19

    Bis-triarylamine 2 and cyclometalated diruthenium 6(PF6)2 with a linear trans,trans-urea bridge have been prepared, together with the bis-triarylamine 3 and cyclometalated diruthenium 8(PF6)2 with a folded cis,cis-N,N-dimethylurea bridge. The linear or folded conformations of these molecules are supported by single-crystal X-ray structures of 2, 3, and other related compounds. These compounds display two consecutive anodic redox waves (N(·+/0) or Ru(III/II) processes) with a potential separation of 110-170 mV. This suggests that an efficient electronic coupling is present between two redox termini through the cross-conjugated urea bridge. The degree of electronic coupling has been investigated by using spectroelectrochemical measurements. Distinct intervalence charge-transfer (IVCT) transitions have been observed for mixed-valent (MV) compounds with a linear conformation. The IVCT transitions can also be identified for the folded MV compounds, albeit with a much weaker intensity. DFT results support that the electronic communication occurs by a through-bond and through-space pathway for the linear and folded compounds, respectively. The IVCT transitions of the MV compounds have been reproduced by TDDFT calculations. For the purpose of comparison, a bistriarylamine and a diruthenium complex with an imidazolidin-2-one bridge and a urea-containing mono-triarylamine and monoruthenium complex have been synthesized and studied.

  5. The mid-infrared signature of photo-induced defects in the quasi-one-dimensional mixed-valence solid [Pt II(en) 2][Pt IV(en) 2Cl 2][ClO 4] 4

    NASA Astrophysics Data System (ADS)

    Donohoe, R. J.; Ekberg, S. A.; Tait, C. D.; Swanson, B. I.

    1989-07-01

    The observation of photo-induced absorption features immediately to the red of the band edge in the halogen-bridged mixed-valence linear chain {[Pt II(en) 2][Pt(en) 2Cl 2][ClO 4]} x (S. Kurita, M. Haruki & K. Miyagawa, J. Phys. Soc. Japan, submitted for publication) has led to the prediction of an associated absorption in the mid-infrared. We have detected this band via difference IR spectroscopic measurements and verified that it tracks the red region absorptions in rate of growth upon photolysis, saturation and in recycling upon warming the sample to room temperature. Based on theoretical predictions, we tentatively assign the mid-IR feature to absorption due to a photo-induced electron polaronic defect.

  6. A Transition from Localized to Strongly Correlated Electron Behavior and Mixed Valence Driven by Physical or Chemical Pressure in ACo2As2 (A = Eu and Ca)

    SciTech Connect

    Tan, Xiaoyan; Fabbris, Gilberto; Haskel, Daniel; Yaroslavtsev, Alexander A.; Cao, Huibo; Thompson, Corey M.; Kovnir, Kirill; Menushenkov, Alexey P.; Chernikov, Roman V.; Garlea, V. Ovidiu; Shatruk, Michael

    2016-02-03

    In this paper, we demonstrate that the action of physical pressure, chemical compression, or aliovalent substitution in ACo2As2 (A = Eu and Ca) has a general consequence of causing these antiferromagnetic materials to become ferromagnets. In all cases, the mixed valence triggered at the electropositive A site results in the increase of the Co 3d density of states at the Fermi level. Remarkably, the dramatic alteration of magnetic behavior results from the very minor (<0.15 electron) change in the population of the 3d orbitals. The mixed valence state of Eu observed in the high-pressure (HP) form of EuCo2As2 exhibits a remarkable stability, achieving the average oxidation state of +2.25 at 12.6 GPa. In the case of CaCo2As2, substituting even 10% of Eu or La into the Ca site causes ferromagnetic ordering of Co moments. Similar to HP-EuCo2As2, the itinerant 3d ferromagnetism emerges from electronic doping into the Co layer because of chemical compression of Eu sites in Ca0.9Eu0.1Co1.91As2 or direct electron doping in Ca0.85La0.15Co1.89As2. Finally, the results reported herein demonstrate the general possibility of amplifying minor localized electronic effects to achieve major changes in material’s properties via involvement of strongly correlated electrons.

  7. 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.

  8. Spatial Heterogeneity in Earthquake Fault-Like Systems

    NASA Astrophysics Data System (ADS)

    Kazemian, J.; Dominguez, R.; Tiampo, K. F.; Klein, W.

    2015-08-01

    The inhomogeneity of materials with different physical properties is responsible for a wide variety of spatial and temporal behavior. In this work, we studied an earthquake fault model based on the Olami-Feder-Christensen and Rundle-Jackson-Brown cellular automata models with particular aspects of spatial heterogeneities and long-range stress interactions. In our model some localized stress accumulators were added into the system by converting a percentage of randomly selected sites into stronger sites that are called `asperity cells'. These asperity cells support much higher failure stresses than the surrounding regular lattice sites but eventually rupture when applied stress reaches their threshold stress. We found that changing the spatial configuration of those stronger sites generally increased the ability of the fault system to generate larger events, but that the total percentage of asperities is important as well. We also observed an increasing number of larger events associated with the total number of asperities in the lattice.

  9. 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. © The Author 2016. Published by Oxford University Press on behalf of the European Society of Cardiology.

  10. 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

  11. Resident database interfaces to the DAVID system, a heterogeneous distributed database management system

    NASA Technical Reports Server (NTRS)

    Moroh, Marsha

    1988-01-01

    A methodology for building interfaces of resident database management systems to a heterogeneous distributed database management system under development at NASA, the DAVID system, was developed. The feasibility of that methodology was demonstrated by construction of the software necessary to perform the interface task. The interface terminology developed in the course of this research is presented. The work performed and the results are summarized.

  12. 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

  13. 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.

  14. HETEROGENEITY OF SYSTEMIC INFLAMMATORY RESPONSES TO PERIODONTAL THERAPY

    PubMed Central

    Behle, Jan H.; Sedaghatfar, Michael H.; Demmer, Ryan T.; Wolf, Dana L.; Celenti, Romanita; Kebschull, Moritz; Belusko, Paul B.; Herrera-Abreu, Miriam; Lalla, Evanthia; Papapanou, Panos N.

    2009-01-01

    Aims We investigated the effect of comprehensive periodontal therapy on the levels of multiple systemic inflammatory biomarkers. Methods Thirty patients with severe periodontitis received comprehensive periodontal therapy within a 6-week period. Blood samples were obtained at: one week pre- therapy (T1), therapy initiation (T2), treatment completion (T3), and 4 weeks thereafter (T4). We assessed plasma concentrations of 19 biomarkers using multiplex assays, and serum IgG antibodies to periodontal bacteria using checkerboard immunoblotting. At T2 and T4, dental plaque samples were analyzed using checkerboard hybridizations. Results At T3, PAI-1, sE-selectin, sVCAM-1, MMP-9, myeloperoxidase, and a composite Summary Inflammatory Score (SIS) were significantly reduced. However, only sE-selectin, sICAM, and serum amyloid P sustained a reduction at T4. Responses were highly variable: analyses of SIS slopes between baseline and T4 showed that approximately 1/3 and 1/4 of the patients experienced marked reduction and pronounced increase in systemic inflammation, respectively, while the remainder were seemingly unchanged. Changes in inflammatory markers correlated poorly with clinical, microbiological and serological markers of periodontitis. Conclusions Periodontal therapy resulted in an overall reduction of systemic inflammation, but the responses were inconsistent across subjects and largely not sustainable. The determinants of this substantial heterogeneity need to be explored further. PMID:19426174

  15. Heterogeneity of systemic inflammatory responses to periodontal therapy.

    PubMed

    Behle, Jan H; Sedaghatfar, Michael H; Demmer, Ryan T; Wolf, Dana L; Celenti, Romanita; Kebschull, Moritz; Belusko, Paul B; Herrera-Abreu, Miriam; Lalla, Evanthia; Papapanou, Panos N

    2009-04-01

    We investigated the effect of comprehensive periodontal therapy on the levels of multiple systemic inflammatory biomarkers. Thirty patients with severe periodontitis received comprehensive periodontal therapy within a 6-week period. Blood samples were obtained at: 1-week pre-therapy (T1), therapy initiation (T2), treatment completion (T3), and 4 weeks thereafter (T4). We assessed the plasma concentrations of 19 biomarkers using multiplex assays, and serum IgG antibodies to periodontal bacteria using checkerboard immunoblotting. At T2 and T4, dental plaque samples were analysed using checkerboard hybridizations. At T3, PAI-1, sE-selectin, sVCAM-1, MMP-9, myeloperoxidase, and a composite summary inflammatory score (SIS) were significantly reduced. However, only sE-selectin, sICAM, and serum amyloid P sustained a reduction at T4. Responses were highly variable: analyses of SIS slopes between baseline and T4 showed that approximately 1/3 and 1/4 of the patients experienced a marked reduction and a pronounced increase in systemic inflammation, respectively, while the remainder were seemingly unchanged. Changes in inflammatory markers correlated poorly with clinical, microbiological and serological markers of periodontitis. Periodontal therapy resulted in an overall reduction of systemic inflammation, but the responses were inconsistent across subjects and largely not sustainable. The determinants of this substantial heterogeneity need to be explored further.

  16. Moving Object Detection in Heterogeneous Conditions in Embedded Systems.

    PubMed

    Garbo, Alessandro; Quer, Stefano

    2017-07-01

    This paper presents a system for moving object exposure, focusing on pedestrian detection, in external, unfriendly, and heterogeneous environments. The system manipulates and accurately merges information coming from subsequent video frames, making small computational efforts in each single frame. Its main characterizing feature is to combine several well-known movement detection and tracking techniques, and to orchestrate them in a smart way to obtain good results in diversified scenarios. It uses dynamically adjusted thresholds to characterize different regions of interest, and it also adopts techniques to efficiently track movements, and detect and correct false positives. Accuracy and reliability mainly depend on the overall receipt, i.e., on how the software system is designed and implemented, on how the different algorithmic phases communicate information and collaborate with each other, and on how concurrency is organized. The application is specifically designed to work with inexpensive hardware devices, such as off-the-shelf video cameras and small embedded computational units, eventually forming an intelligent urban grid. As a matter of fact, the major contribution of the paper is the presentation of a tool for real-time applications in embedded devices with finite computational (time and memory) resources. We run experimental results on several video sequences (both home-made and publicly available), showing the robustness and accuracy of the overall detection strategy. Comparisons with state-of-the-art strategies show that our application has similar tracking accuracy but much higher frame-per-second rates.

  17. Quantifying process heterogeneity: Signal propagation in hydrological systems

    NASA Astrophysics Data System (ADS)

    Lischeid, G.; Merz, C.; Schindler, U.; Schulz, R.; Steidl, J.; Tauschke, R.

    2009-04-01

    Natural hydrological systems are characterized by heterogeneous structures. The typical length scale of the relevant structures is smaller than the resolution of area-covering methods that are available at the catchment-scale. On the other hand these structures are too large to be treated as random effects and are often related to hydrological behaviour in a non-linear way. Consequently, model results, risk assessments etc. are prone to substantial uncertainties. This is often addressed by random realizations of the structures based on given probability density functions and geostatistical properties, and then analysing the resulting effects on hydrological behaviour, e.g., discharge or groundwater table fluctuations, using process-based models. In this study an alternative approach was followed. Hydrological systems usually act as low-pass filters: An input signal (precipitation, groundwater recharge, tracer application, etc.) is damped and delayed during its passage through the system. This study aimed at characterizing the damping behaviour in a quantitative way. Large perturbations usually are transmitted at much higher velocities compared to small perturbations, thus hindering a spectrum analysis based approach. Instead, time series of soil water content, groundwater level and catchment runoff from the Uckermark region in North Germany were analysed using a principal component analysis. In all cases, the first component depicted the mean behaviour, and the second component explained a large fraction of the deviations from the mean behaviour. The loadings of the first two components could be used as an index of the mean damping behaviour for the given time period. Results of the soil water content data showed a linear increase of damping with depth at most sites. However, different sites differed substantially even for backfilled lysimeters that were considered to be homogeneous. There was no clear relationship between clay content and damping behaviour. The

  18. Coarse mesh transport theory model for heterogeneous systems

    NASA Astrophysics Data System (ADS)

    Ilas, Danut

    To improve fuel utilization, recent reactor cores have become substantially more heterogeneous. In these cores, use of variable fuel enrichments and strong absorbers lead to high neutron flux gradients, which may limit the accuracy (validity) of diffusion theory based methods. In fact, the diffusion equation itself may become a poor approximation of the Boltzmann equation, the exact equation that describes the neutron flux. Therefore, numerical methods to solve the transport equation efficiently over a large heterogeneous region (such as a reactor core) are very desirable in case where the diffusion approximation breaks down. Presently, the only methods capable of computing the power (flux) distributions very accurately throughout a large system such as a nuclear reactor core are the Monte-Carlo or the fine-mesh transport theory methods. Both these methods suffer from the long computational time which makes them useless for routine core calculations. Starting from a variational principle that admits trial functions that can be discontinuous at coarse mesh (assembly) interfaces, we propose a method to solve the transport equation on a spatial grid made up of meshes as large as the size of a fuel assembly. The variational principle is derived for the most general case, but further methods are developed for one-dimensional geometry with the angular variable treated by discrete ordinates. The method uses the finite element approach for the space variable with basis functions precomputed for each element to obtain an algebraic linear system of equations. The eigenvalue of this system is the multiplication constant and the eigenvector represents the incoming angular fluxes for each coarse mesh. The latter allows the reconstruction of the fine mesh solution (angular flux) throughout the domain of interest when used with the basis functions (surface Green's function) for each coarse mesh. The method requires no homogenization procedure that can be a serious source of

  19. Local equations of state in nonequilibrium heterogeneous physicochemical systems

    NASA Astrophysics Data System (ADS)

    Tovbin, Yu. K.

    2017-03-01

    Equations describing local thermal and caloric equations of state in heterogeneous systems at any degree of their states' deviation from equilibrium are derived. The state of a system is described by equations of the transfer of mixture components; these generalize the equations of classical non-equilibrium thermodynamics for strongly nonequilibrium processes. The contributions from reactions and external fields are taken into account. The equations are derived using the lattice gas model with discrete molecular distributions in space (on a scale comparable to molecular dimensions) and continuous molecular distributions (at short distances inside cells) during their translational and vibrational motions. For simplicity, it is assumed that distinctions between the sizes of mixture components are small. Contributions from potential functions of intermolecular interaction (of the Lennard-Jones type) to some coordination spheres are considered. The theory provides a unified description of the dynamics of distributions of concentrations and pair functions of mixture components in three aggregate states, and at their interfaces. Universal expressions for the local components of the pressure tensor and internal energy inside multicomponent bulk phases and at their interfaces are obtained. Local components of the pressure tensor and the internal energy are universally expressed through local unary and pair distribution functions (DFs) in any nonequilibrium state. The time evolution of the unary and pair DFs themselves is determined from the derived system of equations of mass, momentum, and energy transfer that ensure the transition of the system from a strongly nonequilibrium state to both the local equilibrium state described within traditional nonequilibrium thermodynamics and the complete thermodynamic equilibrium state postulated by classical thermodynamics.

  20. Spatial heterogeneity in three species, plant-parasite-hyperparasite, systems

    PubMed Central

    White, K. A. J.

    1998-01-01

    This paper addresses the question of how heterogeneity may evolve due to interactions between the dynamics and movement of three-species systems involving hosts, parasites and hyperparasites in homogeneous environments. The models are motivated by the spread of soil-borne parasites within plant populations, where the hyperparasite is used as a biological control agent but where patchiness in the distribution of the parasite occurs, even when environmental conditions are apparently homogeneous. However, the models are introduced in generic form as three-species reaction-diffusion systems so that they have broad applicability to a range of ecological systems. We establish necessary criteria for the occurrence of population-driven patterning via diffusion-driven instability. Sufficient conditions are obtained for restricted cases with no host movement. The criteria are similar to those for the well-documented two-species reaction-diffusion system, although more possibilities arise for spatial patterning with three species. In particular, temporally varying patterns, that may be responsible for the apparent drifting of hot-spots of disease and periodic occurrence of disease at a given location, are possible when three species interact. We propose that the criteria can be used to screen population interactions, to distinguish those that cannot cause patterning from those that may give rise to population-driven patterning. This establishes a basic dynamical 'landscape' against which other perturbations, including environmentally driven variations, can be analysed and distinguished from population-driven patterns. By applying the theory to a specific model example for host-parasite-hyperparasite interactions both with and without host movement, we show directly how the evolution of spatial pattern is related to biologically meaningful parameters. In particular, we demonstrate that when there is strong density dependence limiting host growth, the pattern is stable over

  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.

  3. 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

  4. 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.

  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. Antiferromagnetic porous metal-organic framework containing mixed-valence [Mn(II)4Mn(III)2(μ4-O)2]10+ units with catecholase activity and selective gas adsorption.

    PubMed

    Kar, Paramita; Haldar, Ritesh; Gómez-García, Carlos J; Ghosh, Ashutosh

    2012-04-02

    A multifunctional porous metal organic framework based on mixed-valence hexa-nuclear [Mn(III)(2)Mn(II)(4)O(2)(pyz)(2)(C(6)H(5)CH(2)COO)(10)] (pyz = pyrazine) units has been synthesized. The complex has been characterized by elemental analysis, IR spectroscopy, single-crystal X-ray diffraction analysis, and variable-temperature magnetic measurements. The structural analysis reveals that the bidentate pyz molecules connect each [Mn(6)] unit to its four [Mn(6)] neighbors through the peripheral Mn(II) centers, giving rise to a three-dimensional (3D) distorted diamond-like porous framework. Variable-temperature (2-300 K) magnetic susceptibility measurements show the presence of dominant antiferromagnetic interactions within the discrete [Mn(6)] cluster that have been fitted with a model containing three exchange constants developed for the complex (J(1) = -8.6 cm(-1), J(2) = -3.9 cm(-1), and J(3) = -100.0 cm(-1)). Using 3,5-di-tert-butyl catechol (3,5-DTBC) as the substrate, catecholase activity of the complex has been studied; the turn over number is determined to be of 2547 h(-1) in acetonitrile. This porous compound shows remarkable selectivity for adsorption of CO(2) over N(2) that may be correlated with the effect of window flexibility of the pore to the corresponding adsorbate molecules.

  7. The role of order-disorder transitions in the quest for molecular multiferroics: structural and magnetic neutron studies of a mixed valence iron(II)-iron(III) formate framework.

    PubMed

    Cañadillas-Delgado, Laura; Fabelo, Oscar; Rodríguez-Velamazán, J Alberto; Lemée-Cailleau, Marie-Hélène; Mason, Sax A; Pardo, Emilio; Lloret, Francesc; Zhao, Jiong-Peng; Bu, Xian-He; Simonet, Virginie; Colin, Claire V; Rodríguez-Carvajal, Juan

    2012-12-05

    Neutron diffraction studies have been carried out to shed light on the unprecedented order-disorder phase transition (ca. 155 K) observed in the mixed-valence iron(II)-iron(III) formate framework compound [NH(2)(CH(3))(2)](n)[Fe(III)Fe(II)(HCOO)(6)](n). The crystal structure at 220 K was first determined from Laue diffraction data, then a second refinement at 175 K and the crystal structure determination in the low temperature phase at 45 K were done with data from the monochromatic high resolution single crystal diffractometer D19. The 45 K nuclear structure reveals that the phase transition is associated with the order-disorder of the dimethylammonium counterion that is weakly anchored in the cavities of the [Fe(III)Fe(II)(HCOO)(6)](n) framework. In the low-temperature phase, a change in space group from P31c to R3c occurs, involving a tripling of the c-axis due to the ordering of the dimethylammonium counterion. The occurrence of this nuclear phase transition is associated with an electric transition, from paraelectric to antiferroelectric. A combination of powder and single crystal neutron diffraction measurements below the magnetic order transition (ca. 37 K) has been used to determine unequivocally the magnetic structure of this Néel N-Type ferrimagnet, proving that the ferrimagnetic behavior is due to a noncompensation of the different Fe(II) and Fe(III) magnetic moments.

  8. A Modular Environment for Geophysical Inversion and Run-time Autotuning using Heterogeneous Computing Systems

    NASA Astrophysics Data System (ADS)

    Myre, Joseph M.

    Heterogeneous computing systems have recently come to the forefront of the High-Performance Computing (HPC) community's interest. HPC computer systems that incorporate special purpose accelerators, such as Graphics Processing Units (GPUs), are said to be heterogeneous. Large scale heterogeneous computing systems have consistently ranked highly on the Top500 list since the beginning of the heterogeneous computing trend. By using heterogeneous computing systems that consist of both general purpose processors and special- purpose accelerators, the speed and problem size of many simulations could be dramatically increased. Ultimately this results in enhanced simulation capabilities that allows, in some cases for the first time, the execution of parameter space and uncertainty analyses, model optimizations, and other inverse modeling techniques that are critical for scientific discovery and engineering analysis. However, simplifying the usage and optimization of codes for heterogeneous computing systems remains a challenge. This is particularly true for scientists and engineers for whom understanding HPC architectures and undertaking performance analysis may not be primary research objectives. To enable scientists and engineers to remain focused on their primary research objectives, a modular environment for geophysical inversion and run-time autotuning on heterogeneous computing systems is presented. This environment is composed of three major components: 1) CUSH---a framework for reducing the complexity of programming heterogeneous computer systems, 2) geophysical inversion routines which can be used to characterize physical systems, and 3) run-time autotuning routines designed to determine configurations of heterogeneous computing systems in an attempt to maximize the performance of scientific and engineering codes. Using three case studies, a lattice-Boltzmann method, a non-negative least squares inversion, and a finite-difference fluid flow method, it is shown that

  9. Topological Properties and the Dynamical Crossover from Mixed-Valence to Kondo-Lattice Behavior in the Golden Phase of SmS.

    PubMed

    Kang, Chang-Jong; Choi, Hong Chul; Kim, Kyoo; Min, B I

    2015-04-24

    We have investigated temperature-dependent behaviors of electronic structure and resistivity in a mixed-valent golden phase of SmS, based on the dynamical mean-field-theory band-structure calculations. Upon cooling, the coherent Sm 4f bands are formed to produce the hybridization-induced pseudogap near the Fermi level, and accordingly the topology of the Fermi surface is changed to exhibit a Lifshitz-like transition. The surface states emerging in the bulk gap region are found to be not topologically protected states but just typical Rashba spin-polarized states, indicating that SmS is not a topological Kondo semimetal. From the analysis of anomalous resistivity behavior in SmS, we have identified universal energy scales, which characterize the Kondo-mixed-valent semimetallic systems.

  10. Changes, Consistency and Configuration in Heterogeneous, Distributed Systems

    DTIC Science & Technology

    1999-05-01

    The objective of the effort was to develop a unifying framework for change management and automatic change notification suitable for diverse...follows: (1) We designed and implemented a model for change management in heterogeneous information sources. The model, called DOEM (for Delta-OEM) is

  11. 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.

  12. 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

  13. Heterogeneous databases integration in a hospital information systems environment: a bottom-up approach.

    PubMed Central

    Kamel, M. N.; Zviran, M.

    1991-01-01

    The paper describes the problem of heterogeneous databases, discusses the need for an integrated hospital information system and provides a five-step method for integrating heterogeneous databases in the hospital environment. The scope of this method facilitates the integration of medical, administrative and fiscal information elements of a hospital into a unified environment. PMID:1807623

  14. 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.

  15. Consensus of Heterogeneous Linear Multiagent Systems With Communication Time-Delays.

    PubMed

    Xu, Xiang; Liu, Lu; Feng, Gang

    2017-05-23

    This paper studies the consensus problem of heterogeneous linear multiagent systems with arbitrarily large constant, time-varying, or distributed communication delays. Novel distributed dynamic controllers are proposed for such multiagent systems with fixed and switching directed communication topologies, respectively. It is shown that the controlled heterogeneous linear multiagent system can reach consensus for arbitrarily large constant, time-varying, and distributed communication delays under some sufficient conditions. Simulation examples are provided to demonstrate the effectiveness of the proposed controllers.

  16. Synthesis, Characterization, and Photochemistry of a Dinuclear Cyanide-Bridged Iron(II)-Platinum(IV) Mixed-Valence Compound and Its Implications for the Corresponding Iron(II)-Platinum(IV)-Iron(II) Complex.

    PubMed

    Pfennig, Brian W.; Lockard, Jenny V.; Cohen, Jamie L.; Watson, David F.; Ho, Douglas M.; Bocarsly, Andrew B.

    1999-06-14

    The mixed-valence compound [(NH(3))(5)Pt(IV)(&mgr;-NC)Fe(II)(CN)(5)].6H(2)O was synthesized by the substitution reaction of [Pt(IV)(NH(3))(5)OSO(2)CF(3)](OSO(2)CF(3))(3) and [Fe(II)(CN)(6)](4)(-) in aqueous solution and was characterized by UV/vis, IR, and resonance Raman spectroscopies, cyclic voltammetry, and single-crystal X-ray diffractometry. The monoclinic crystal (space group P2(1)/m (No. 11)) consists of a dinuclear, cyanide-bridged Fe(II)-Pt(IV) moiety with unit cell dimensions of a = 9.3241(5) Å, b = 14.0466(7) Å, c = 9.6938(4) Å, beta = 111.467(2) degrees, and Z = 2. There are also an average of six waters of hydration per unit cell. The R-factors for this structure are R = 3.66% and R(w) = 7.90%. The electronic spectrum reveals a broad intervalent (IT) charge-transfer absorption at approximately 420 nm (epsilon = 540 M(-)(1) cm(-)(1)). Both the ground-state spectroscopy and the electrochemistry of this compound are very similar to those of the corresponding trinuclear adduct [(NC)(5)Fe(II)(&mgr;-CN)Pt(IV)(NH(3))(4)(&mgr;-NC)Fe(II)(CN)(5)](4)(-), which has been reported previously. Classical Marcus-Hush theory has been applied in the analysis of the IT band of the dinuclear compound in an effort to elucidate a fuller understanding of the photophysics of the trinuclear complex. The data suggest that this latter, centrosymmetric species can be treated theoretically as two back-to-back dinuclear donor-acceptor (D-A) compounds of the form D-A/A-D, where the Pt(IV) inversion center acts as the acceptor for both halves of the molecule. The photochemistry of the dinuclear complex was also investigated.

  17. Sampled-Data-Based Consensus and $L_{2}$ -Gain Analysis for Heterogeneous Multiagent Systems.

    PubMed

    Du, Sheng-Li; Xia, Weiguo; Sun, Xi-Ming; Wang, Wei

    2017-06-01

    This paper is concerned with the sampled-data-based consensus problem of heterogeneous multiagent systems under directed graph topology with communication failure. The heterogeneous multiagent system consists of first-order and second-order integrators. Consensus of the heterogeneous multiagent system may not be guaranteed if the communication failure always happens. However, if the frequency and the length of the communication failure satisfy certain conditions, consensus of the considered system can be reached. In particular, we introduce the concepts of communication failure frequency and communication failure length. Then, with the help of the switching technique and the Lyapunov stability theory, sufficient conditions are derived in terms of linear matrix inequalities, which guarantees that the heterogeneous multiagent system not only achieves consensus but also maintains a desired L2 -gain performance. A simulation example is given to show the effectiveness of the proposed method in this paper.

  18. Aquifer Heterogeneity and Solute-Transport Modeling in the Floridan Aquifer System

    NASA Astrophysics Data System (ADS)

    Guo, W.; Maliva, R. G.; Missimer, T. M.

    2008-05-01

    The Floridan Aquifer System (FAS) is one of the most prolific aquifers in the world and is widely used for public and irrigation water supply. The FAS is also increasingly being used as a storage zone for aquifer storage and recovery (ASR) systems, including a 333-well system that is planned as part of the Comprehensive Everglades Restoration Plan (CERP). The FAS is highly heterogeneous with respect to hydraulic conductivity, with meter- scale inter-bed variation exceeding seven orders of magnitude in some cases, even in South Florida where mega-karst is not well developed. Aquifer heterogeneity can have a major impact on ASR system performance because of its affects on the movement and mixing of stored water. Aquifer heterogeneity poses challenges for accurate modeling of the FAS, including solute transport modeling of ASR systems and variable density flow modeling of the freshwater/saltwater interface along coastal areas. Dispersivity is an important parameter in solute transport modeling, which is associated with aquifer heterogeneity. Commonly the values of dispersivity used in solute-transport modeling are derived from literature review and adjusted during model calibration process. Artificially large dispersivity values are often used in solute-transport models of ASR systems as a "fudge factor" to simulate the apparent greater mixing caused by inter-bed heterogeneity. This approach is problematic because the use of artificial hydraulic parameters for calibration opens the results of predictive simulations to question. The use of large dispersivity values to simulate aquifer heterogeneity also does not incorporate other impacts of aquifer heterogeneity, such as differential flow rates and migration distances between beds. The technical challenge is to incorporate aquifer heterogeneity into groundwater models at a scale that is sufficient to adequately simulate its effect on ASR system performance and coastal groundwater flow, while maintaining acceptable

  19. Averaging over spatial heterogeneity leads to overestimation of ET in large scale Earth system models

    NASA Astrophysics Data System (ADS)

    Rouholahnejad Freund, Elham; Fan, Ying; Kirchner, James W.

    2017-04-01

    Hydrologic processes are heterogeneous at far smaller spatial scales than a typical Earth system model grid (1-5 degree, 100-500km). Thus, estimates of evapotranspiration (ET) in most Earth system models average over considerable sub-grid heterogeneity in land surface properties, precipitation (P), and potential evapotranspiration (PET). This spatial averaging could potentially bias ET estimates, due to the nonlinearities in the underlying relationships. Here we estimate the effects of spatial heterogeneity on grid-cell-averaged ET, as seen from the atmosphere over heterogeneous landscapes at global scale. Using a Budyko framework to express ET as a function of P and PET, we quantify how sub-grid heterogeneity affects average ET at the scale of typical Earth system model grid cells (1° by 1°). We show that averaging over sub-grid heterogeneity in P and PET, as typical Earth system models do, leads to overestimation of average ET. Our analysis at global scale shows that the effects of sub-grid heterogeneity will be most pronounced in steep mountainous areas where the topographic gradient is high and where P is inversely correlated with PET across the landscape. This approach yields a simple conceptual framework and mathematical expressions for determining whether, and how much, spatial heterogeneity can affect regional ET fluxes as seen from the atmosphere. Correcting for this overestimation of ET in Earth system models will be important for future temperature predictions, since smaller values of ET imply greater sensible heat fluxes, thus potentially amplifying dry and warm conditions in the context of climate change. This work presented here provides the basis for translating the quantified heterogeneity bias into correction factors for large scale Earth system models, which will be the focus of future work.

  20. Heterogeneous Atomistic-Continuum Methods for Dense Fluid Systems

    NASA Astrophysics Data System (ADS)

    Hadjiconstantinou, Nicolas; Patera, Anthony

    1997-08-01

    We present new results obtained using the formulation and numerical solution procedure for heterogeneous atomistic--continuum representations of fluid flows presented in [1]. The ingredients are, from the atomistic side, non-equilibrium molecular dynamics, and from the continuum side, finite element solution; the matching is provided by a classical procedure, the Schwarz alternating method with overlapping subdomains. The technique is applied to the flow of two immiscible fluids in a microscale channel. The problem "presents" a particular modelling challenge because of the stress singularity at the moving contact line which is usually relieved through ad hoc methods, the most popular of which is the assumption of slip close to the contact line. The Heterogeneous method properly addresses the problem by treating the region near the contact line with molecular dynamics. References 1. Hadjiconstantinou N., Patera, A.T., Proceedings of the Sixth International Conference on Discrete Models for Fluid Mechanics, To appear as a special edition of the International Journal of Modern Physics C.

  1. Heterogeneity in Pure Microbial Systems: Experimental Measurements and Modeling

    PubMed Central

    González-Cabaleiro, Rebeca; Mitchell, Anca M.; Smith, Wendy; Wipat, Anil; Ofiţeru, Irina D.

    2017-01-01

    Cellular heterogeneity influences bioprocess performance in ways that until date are not completely elucidated. In order to account for this phenomenon in the design and operation of bioprocesses, reliable analytical and mathematical descriptions are required. We present an overview of the single cell analysis, and the mathematical modeling frameworks that have potential to be used in bioprocess control and optimization, in particular for microbial processes. In order to be suitable for bioprocess monitoring, experimental methods need to be high throughput and to require relatively short processing time. One such method used successfully under dynamic conditions is flow cytometry. Population balance and individual based models are suitable modeling options, the latter one having in particular a good potential to integrate the various data collected through experimentation. This will be highly beneficial for appropriate process design and scale up as a more rigorous approach may prevent a priori unwanted performance losses. It will also help progressing synthetic biology applications to industrial scale. PMID:28970826

  2. Mixed valency of Cu, electron-mass enhancement, and three-dimensional arrangement of magnetic sites in the organic conductors (R1,R2-N,N'-dicyanoquinonediimine)2Cu (where R1,R2=CH3,CH3O,Cl,Br)

    NASA Astrophysics Data System (ADS)

    Kobayashi, H.; Miyamoto, A.; Kato, R.; Sakai, F.; Kobayashi, A.; Yamakita, Y.; Furukawa, Y.; Tasumi, M.; Watanabe, T.

    1993-02-01

    The unique molecular conductors with pπ-d mixing band structures (R1,R2-N,N'-dicyanoquinonediimine)2Cu [(R1,R2-DCNQI)2Cu] (R1,R2=CH3,CH3O,Cl,Br) were examined. General features of the phase diagram of the DCNQI-Cu system were depicted. A region that is related to the existence of anomalously heavy-metal electrons has been found. The T2 dependence of the low-temperature resistivity of the alloyed system (DMe1-xMeBrx-DCNQI)2Cu (where Me=CH3) suggests a large enhancement of the electron mass at the critical situation where the system begins to exhibit a characteristic metal instability. The mixed valency of Cu (Cu+1.3) in (DMe-DCNQI)2Cu was confirmed by ir experiments performed on neutral DMe-DCNQI crystals and (DMe-DCNQI)2M (M=Li, Ba, Cu). The same conclusion was also derived from a low-temperature x-ray-diffraction experiment. The gradual temperature dependences of the ir absorption intensities of totally symmetric modes of (DBr-DCNQI)2Cu observed below the metal-insulator transition temperature (TMI) are in contrast with the discontinuous resistivity and susceptibility changes at TMI. This may be attributable to the existence of two driving forces characterizing the M-I transition. One is the sharp charge ordering in Cu sites and the other is the continuous development of charge-density waves on DCNQI stacks. The arrangement of Cu2+ and Cu+ below TMI was determined by an x-ray crystal-structure analysis of the threefold insulating phase of (MeBr-DCNQI)2Cu at 110 K. The nearest-neighbor Cu2+ ions interact with each other via two DCNQI molecules. A plausible spin structure of the antiferromagnetic ground state was proposed. According to this spin-structure model, the magnetic moments of Cu2+ along the crystallographic c axis will be arranged ferromagnetically.

  3. Dithiolate complexes of manganese and rhenium: X-ray structure and properties of an unusual mixed valence cluster Mn3(CO)6(mu-eta2-SCH2CH2CH2S)3.

    PubMed

    Begum, Noorjahan; Hyder, Md Iqbal; Kabir, Shariff E; Hossain, G M Golzar; Nordlander, Ebbe; Rokhsana, Dalia; Rosenberg, Edward

    2005-12-26

    Treatment of Mn(2)(CO)(10) with 3,4-toluenedithiol and 1,2-ethanedithiol in the presence of Me(3)NO.2H(2)O in CH(2)Cl(2) at room temperature afforded the dinuclear complexes Mn(2)(CO)(6)(mu-eta(4)-SC(6)H(3)(CH(3))S-SC(6)H(3)(CH(3))S) (1), and Mn(2)(CO)(6)(mu-eta(4)-SCH(2)CH(2)S-SCH(2)CH(2)S) (2), respectively. Similar reactions of Re(2)(CO)(10) with 3,4-toluenedithiol, 1,2-benzenedithiol, and 1,2-ethanedithiol yielded the dirhenium complexes Re(2)(CO)(6)(mu-eta(4)-SC(6)H(3)(CH(3))S-SC(6)H(3)(CH(3))S) (3), Re(2)(CO)(6)(mu-eta(4)-SC(6)H(4)S-SC(6)H(4)S) (4), and Re(2)(CO)(6)(SCH(2)CH(2)S-SCH(2)CH(2)S) (5), respectively. In contrast, treatment of Mn(2)(CO)(10) with 1,3-propanedithiol afforded the trimanganese compound Mn(3)(CO)(6)(mu-eta(2)-SCH(2)CH(2)CH(2)S)(3) (6), whereas Re(2)(CO)(10) gave only intractable materials. The molecular structures of 1, 3, and 6 have been determined by single-crystal X-ray diffraction studies. The dimanganese and dirhenium carbonyl compounds 1-5contain a binucleating disulfide ligand, formed by interligand disulfide bond formation between two dithiolate ligands identical in structure to that of the previously reported dimanganese complex Mn(2)(CO)(6)(mu-eta(4)-SC(6)H(4)S-SC(6)H(4)S). Complex 6, on the other hand, forms a unique example of a mixed-valence trimangenese carbonyl compound containing three bridging 1,3-propanedithiolate ligands. The solution properties of 6 have been investigated by UV-vis and EPR spectroscopies as well as electrochemical techniques.

  4. 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.

  5. Influence of macrofaunal assemblages and environmental heterogeneity on microphytobenthic production in experimental systems

    PubMed Central

    Dyson, Kirstie E; Bulling, Mark T; Solan, Martin; Hernandez-Milian, Gema; Raffaelli, David G; White, Piran C.L; Paterson, David M

    2007-01-01

    Despite the complexity of natural systems, heterogeneity caused by the fragmentation of habitats has seldom been considered when investigating ecosystem processes. Empirical approaches that have included the influence of heterogeneity tend to be biased towards terrestrial habitats; yet marine systems offer opportunities by virtue of their relative ease of manipulation, rapid response times and the well-understood effects of macrofauna on sediment processes. Here, the influence of heterogeneity on microphytobenthic production in synthetic estuarine assemblages is examined. Heterogeneity was created by enriching patches of sediment with detrital algae (Enteromorpha intestinalis) to provide a source of allochthonous organic matter. A gradient of species density for four numerically dominant intertidal macrofauna (Hediste diversicolor, Hydrobia ulvae, Corophium volutator, Macoma balthica) was constructed, and microphytobenthic biomass at the sediment surface was measured. Statistical analysis using generalized least squares regression indicated that heterogeneity within our system was a significant driving factor that interacted with macrofaunal density and species identity. Microphytobenthic biomass was highest in enriched patches, suggesting that nutrients were obtained locally from the sediment–water interface and not from the water column. Our findings demonstrate that organic enrichment can cause the development of heterogeneity which influences infaunal bioturbation and consequent nutrient generation, a driver of microphytobenthic production. PMID:17698480

  6. Influence of macrofaunal assemblages and environmental heterogeneity on microphytobenthic production in experimental systems.

    PubMed

    Dyson, Kirstie E; Bulling, Mark T; Solan, Martin; Hernandez-Milian, Gema; Raffaelli, David G; White, Piran C L; Paterson, David M

    2007-10-22

    Despite the complexity of natural systems, heterogeneity caused by the fragmentation of habitats has seldom been considered when investigating ecosystem processes. Empirical approaches that have included the influence of heterogeneity tend to be biased towards terrestrial habitats; yet marine systems offer opportunities by virtue of their relative ease of manipulation, rapid response times and the well-understood effects of macrofauna on sediment processes. Here, the influence of heterogeneity on microphytobenthic production in synthetic estuarine assemblages is examined. Heterogeneity was created by enriching patches of sediment with detrital algae (Enteromorpha intestinalis) to provide a source of allochthonous organic matter. A gradient of species density for four numerically dominant intertidal macrofauna (Hediste diversicolor, Hydrobia ulvae, Corophium volutator, Macoma balthica) was constructed, and microphytobenthic biomass at the sediment surface was measured. Statistical analysis using generalized least squares regression indicated that heterogeneity within our system was a significant driving factor that interacted with macrofaunal density and species identity. Microphytobenthic biomass was highest in enriched patches, suggesting that nutrients were obtained locally from the sediment-water interface and not from the water column. Our findings demonstrate that organic enrichment can cause the development of heterogeneity which influences infaunal bioturbation and consequent nutrient generation, a driver of microphytobenthic production.

  7. Distributed containment control of heterogeneous fractional-order multi-agent systems with communication delays

    NASA Astrophysics Data System (ADS)

    Yang, Hongyong; Han, Fujun; Zhao, Mei; Zhang, Shuning; Yue, Jun

    2017-08-01

    Because many networked systems can only be characterized with fractional-order dynamics in complex environments, fractional-order calculus has been studied deeply recently. When diverse individual features are shown in different agents of networked systems, heterogeneous fractional-order dynamics will be used to describe the complex systems. Based on the distinguishing properties of agents, heterogeneous fractional-order multi-agent systems (FOMAS) are presented. With the supposition of multiple leader agents in FOMAS, distributed containment control of FOMAS is studied in directed weighted topologies. By applying Laplace transformation and frequency domain theory of the fractional-order operator, an upper bound of delays is obtained to ensure containment consensus of delayed heterogenous FOMAS. Consensus results of delayed FOMAS in this paper can be extended to systems with integer-order models. Finally, numerical examples are used to verify our results.

  8. Robust Architectures for Complex Multi-Agent Heterogeneous Systems

    DTIC Science & Technology

    2014-07-23

    Bode-Like Integral for Stochastic Switched Systems with Applications in Networked Control Systems and Macroeconomics , In Proceedings of American...Raymarine has successfully implemented Adaptive Control on their Evolution Autopilot series for marine vessels.  Unmanned Dynamics multirotor solutions

  9. 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.

  10. Chemotaxis-induced spatio-temporal heterogeneity in multi-species host-parasitoid systems.

    PubMed

    Pearce, Ian G; Chaplain, Mark A J; Schofield, Pietà G; Anderson, Alexander R A; Hubbard, Stephen F

    2007-09-01

    When searching for hosts, parasitoids are observed to aggregate in response to chemical signalling cues emitted by plants during host feeding. In this paper we model aggregative parasitoid behaviour in a multi-species host-parasitoid community using a system of reaction-diffusion-chemotaxis equations. The stability properties of the steady-states of the model system are studied using linear stability analysis which highlights the possibility of interesting dynamical behaviour when the chemotactic response is above a certain threshold. We observe quasi-chaotic dynamic heterogeneous spatio-temporal patterns, quasi-stationary heterogeneous patterns and a destabilisation of the steady-states of the system. The generation of heterogeneous spatio-temporal patterns and destabilisation of the steady state are due to parasitoid chemotactic response to hosts. The dynamical behaviour of our system has both mathematical and ecological implications and the concepts of chemotaxis-driven instability and coexistence and ecological change are discussed.

  11. Internal and Boundary Observability Estimates for the Heterogeneous Maxwell's System

    SciTech Connect

    Nicaise, Serge Pignotti, Cristina

    2006-06-15

    Observability estimates for Maxwell's system with variable coefficients are established using the differential geometry method recently developed for scalar wave equations.The main tool is that Maxwell's system is reducible to a perturbed vectorial wave equation with a decoupled principal part.

  12. HARNESS: Heterogeneous Adaptable Reconfigurable Networked Systems. Final Progress Report

    SciTech Connect

    Fagg, G. E.

    2004-01-20

    HARNESS was proposed as a system that combined the best of emerging technologies found in current distributed computing research and commercial products into a very flexible, dynamically adaptable framework that could be used by applications to allow them to evolve and better handle their execution environment. The HARNESS system was designed using the considerable experience from previous projects such as PVM, MPI, IceT and Cumulvs. As such, the system was designed to avoid any of the common problems found with using these current systems, such as no single point of failure, ability to survive machine, node and software failures. Additional features included improved intercomponent connectivity, with full support for dynamic down loading of addition components at run-time thus reducing the stress on application developers to build in all the libraries they need in advance.

  13. Managing Heterogeneous Information Systems through Discovery and Retrieval of Generic Concepts.

    ERIC Educational Resources Information Center

    Srinivasan, Uma; Ngu, Anne H. H.; Gedeon, Tom

    2000-01-01

    Introduces a conceptual integration approach to heterogeneous databases or information systems that exploits the similarity in metalevel information and performs metadata mining on database objects to discover a set of concepts that serve as a domain abstraction and provide a conceptual layer above existing legacy systems. Presents results of…

  14. Output Consensus of Heterogeneous Linear Discrete-Time Multiagent Systems With Structural Uncertainties.

    PubMed

    Li, Shaobao; Feng, Gang; Luo, Xiaoyuan; Guan, Xinping

    2015-12-01

    This paper investigates the output consensus problem of heterogeneous discrete-time multiagent systems with individual agents subject to structural uncertainties and different disturbances. A novel distributed control law based on internal reference models is first presented for output consensus of heterogeneous discrete-time multiagent systems without structural uncertainties, where internal reference models embedded in controllers are designed with the objective of reducing communication costs. Then based on the distributed internal reference models and the well-known internal model principle, a distributed control law is further presented for output consensus of heterogeneous discrete-time multiagent systems with structural uncertainties. It is shown in both cases that the consensus trajectory of the internal reference models determines the output trajectories of agents. Finally, numerical simulation results are provided to illustrate the effectiveness of the proposed control schemes.

  15. Gas phase metal cluster model systems for heterogeneous catalysis.

    PubMed

    Lang, Sandra M; Bernhardt, Thorsten M

    2012-07-14

    Since the advent of intense cluster sources, physical and chemical properties of isolated metal clusters are an active field of research. In particular, gas phase metal clusters represent ideal model systems to gain molecular level insight into the energetics and kinetics of metal-mediated catalytic reactions. Here we summarize experimental reactivity studies as well as investigations of thermal catalytic reaction cycles on small gas phase metal clusters, mostly in relation to the surprising catalytic activity of nanoscale gold particles. A particular emphasis is put on the importance of conceptual insights gained through the study of gas phase model systems. Based on these concepts future perspectives are formulated in terms of variation and optimization of catalytic materials e.g. by utilization of bimetals and metal oxides. Furthermore, the future potential of bio-inspired catalytic material systems are highlighted and technical developments are discussed.

  16. Data Storing Proposal from Heterogeneous Systems into a Specialized Repository

    NASA Astrophysics Data System (ADS)

    Václavová, Andrea; Tanuška, Pavol; Jánošík, Ján

    2016-12-01

    The aim of this paper is to analyze and to propose an appropriate system for processing and simultaneously storing a vast volume of structured and unstructured data. The paper consists of three parts. The first part addresses the issue of structured and unstructured data. The second part provides the detailed analysis of data repositories and subsequent evaluation indicating which system would be for the given type and volume of data optimal. The third part focuses on the use of gathered information to transfer data to the proposed repository.

  17. 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. 2010 Elsevier B.V. All rights reserved.

  18. 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

  19. Multi-heuristic dynamic task allocation using genetic algorithms in a heterogeneous distributed system

    PubMed Central

    Page, Andrew J.; Keane, Thomas M.; Naughton, Thomas J.

    2010-01-01

    We present a multi-heuristic evolutionary task allocation algorithm to dynamically map tasks to processors in a heterogeneous distributed system. It utilizes a genetic algorithm, combined with eight common heuristics, in an effort to minimize the total execution time. It operates on batches of unmapped tasks and can preemptively remap tasks to processors. The algorithm has been implemented on a Java distributed system and evaluated with a set of six problems from the areas of bioinformatics, biomedical engineering, computer science and cryptography. Experiments using up to 150 heterogeneous processors show that the algorithm achieves better efficiency than other state-of-the-art heuristic algorithms. PMID:20862190

  20. Multi-heuristic dynamic task allocation using genetic algorithms in a heterogeneous distributed system.

    PubMed

    Page, Andrew J; Keane, Thomas M; Naughton, Thomas J

    2010-07-01

    We present a multi-heuristic evolutionary task allocation algorithm to dynamically map tasks to processors in a heterogeneous distributed system. It utilizes a genetic algorithm, combined with eight common heuristics, in an effort to minimize the total execution time. It operates on batches of unmapped tasks and can preemptively remap tasks to processors. The algorithm has been implemented on a Java distributed system and evaluated with a set of six problems from the areas of bioinformatics, biomedical engineering, computer science and cryptography. Experiments using up to 150 heterogeneous processors show that the algorithm achieves better efficiency than other state-of-the-art heuristic algorithms.

  1. Group consensus control for heterogeneous multi-agent systems with fixed and switching topologies

    NASA Astrophysics Data System (ADS)

    Wen, Guoguang; Huang, Jun; Wang, Chunyan; Chen, Zhi; Peng, Zhaoxia

    2016-02-01

    In this paper, the group consensus problems of heterogeneous multi-agent systems with fixed and switching topologies are investigated. First, a class of distributed group consensus protocol is proposed for achieving the group consensus of heterogeneous multi-agent systems by using the neighbours' information. Then, some corresponding sufficient conditions are obtained to guarantee the achievement of group consensus. Rigorous proofs are given by using graph theory, matrix theory and Lyapunov theory. Finally, numerical simulations are also given to verify the theoretical analysis.

  2. 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.

  3. Heterogeneous computing for a real-time pig monitoring system

    NASA Astrophysics Data System (ADS)

    Choi, Younchang; Kim, Jinseong; Kim, Jaehak; Chung, Yeonwoo; Chung, Yongwha; Park, Daihee; Kim, Hakjae

    2017-06-01

    Video sensor data has been widely used in automatic surveillance applications. In this study, we present a method that automatically detects pigs in a pig room by using depth information obtained from a Kinect sensor. For a real-time implementation, we propose a means of reducing the execution time by applying parallel processing techniques. In general, most parallel processing techniques have been used to parallelize a specific task. In this study, we consider parallelization of an entire system that consists of several tasks. By applying a scheduling strategy to identify a computing device for each task and implementing it with OpenCL, we can reduce the total execution time efficiently. Experimental results reveal that the proposed method can automatically detect pigs using a CPU-GPU hybrid system in real time, regardless of the relative performance between the CPU and GPU.

  4. Fusion of Heterogeneous Intrusion Detection Systems for Network Attack Detection.

    PubMed

    Kaliappan, Jayakumar; Thiagarajan, Revathi; Sundararajan, Karpagam

    2015-01-01

    An intrusion detection system (IDS) helps to identify different types of attacks in general, and the detection rate will be higher for some specific category of attacks. This paper is designed on the idea that each IDS is efficient in detecting a specific type of attack. In proposed Multiple IDS Unit (MIU), there are five IDS units, and each IDS follows a unique algorithm to detect attacks. The feature selection is done with the help of genetic algorithm. The selected features of the input traffic are passed on to the MIU for processing. The decision from each IDS is termed as local decision. The fusion unit inside the MIU processes all the local decisions with the help of majority voting rule and makes the final decision. The proposed system shows a very good improvement in detection rate and reduces the false alarm rate.

  5. Fusion of Heterogeneous Intrusion Detection Systems for Network Attack Detection

    PubMed Central

    Kaliappan, Jayakumar; Thiagarajan, Revathi; Sundararajan, Karpagam

    2015-01-01

    An intrusion detection system (IDS) helps to identify different types of attacks in general, and the detection rate will be higher for some specific category of attacks. This paper is designed on the idea that each IDS is efficient in detecting a specific type of attack. In proposed Multiple IDS Unit (MIU), there are five IDS units, and each IDS follows a unique algorithm to detect attacks. The feature selection is done with the help of genetic algorithm. The selected features of the input traffic are passed on to the MIU for processing. The decision from each IDS is termed as local decision. The fusion unit inside the MIU processes all the local decisions with the help of majority voting rule and makes the final decision. The proposed system shows a very good improvement in detection rate and reduces the false alarm rate. PMID:26295058

  6. Temporal Heterogeneity and the Value of Slowness in Robotic Systems

    DTIC Science & Technology

    2015-11-01

    aspect of robot ecosystems consisting of fast and slow robots (SlowBots) working together, including the bio-inspiration for such systems. I...contrast to this, nature has found that in certain cases, being slow is better, or at least that the same ecosystem is successfully populated by slow...robots in conjunction with fast ones. Tree sloths, slow lorises, and natural ecosystems are used as inspiration for this work. * Research supported

  7. Extent of reaction in open systems with multiple heterogeneous reactions

    USGS Publications Warehouse

    Friedly, John C.

    1991-01-01

    The familiar batch concept of extent of reaction is reexamined for systems of reactions occurring in open systems. Because species concentrations change as a result of transport processes as well as reactions in open systems, the extent of reaction has been less useful in practice in these applications. It is shown that by defining the extent of the equivalent batch reaction and a second contribution to the extent of reaction due to the transport processes, it is possible to treat the description of the dynamics of flow through porous media accompanied by many chemical reactions in a uniform, concise manner. This approach tends to isolate the reaction terms among themselves and away from the model partial differential equations, thereby enabling treatment of large problems involving both equilibrium and kinetically controlled reactions. Implications on the number of coupled partial differential equations necessary to be solved and on numerical algorithms for solving such problems are discussed. Examples provided illustrate the theory applied to solute transport in groundwater flow.

  8. Heterogeneity of nervous system mitochondria: location, location, location!

    PubMed

    Dubinsky, Janet M

    2009-08-01

    Mitochondrial impairments have been associated with many neurological disorders, from inborn errors of metabolism or genetic disorders to age and environmentally linked diseases of aging (DiMauro S., Schon E.A. 2008. Mitochondrial disorders in the nervous system. Annu. Rev., Neurosci. 31, 91-123.). In these disorders, specific nervous system components or brain regions appear to be initially more susceptible to the triggering event or pathological process. Such regional variation in susceptibility to multiple types of stressors raises the possibility that inherent differences in mitochondrial function may mediate some aspect of pathogenesis. Regional differences in the distribution or number of mitochondria, mitochondrial enzyme activities, enzyme expression levels, mitochondrial genes or availability of necessary metabolites become attractive explanations for selective vulnerability of a nervous system structure. While regionally selective mitochondrial vulnerability has been documented, regional variations in other cellular and tissue characteristics may also contribute to metabolic impairment. Such environmental variables include high tonic firing rates, neurotransmitter phenotype, location of mitochondria within a neuron, or the varied tissue perfusion pressure of different cerebral arterial branches. These contextual variables exert regionally distinct regulatory influences on mitochondria to tune their energy production to local demands. Thus to understand variations in mitochondrial functioning and consequent selective vulnerability to injury, the organelle must be placed within the context of its cellular, functional, developmental and neuroanatomical environment.

  9. 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.

  10. Analyzing Heterogeneous Complexity in Complementary and Alternative Medicine Research: A Systems Biology Solution via Parsimony Phylogenetics

    PubMed Central

    Abu-Asab, Mones; Koithan, Mary; Shaver, Joan; Amri, Hakima

    2012-01-01

    Summary Systems biology offers cutting-edge tools for the study of complementary and alternative medicine (CAM). The advent of ‘omics’ techniques and the resulting avalanche of scientific data have introduced an unprecedented level of complexity and heterogeneous data to biomedical research, leading to the development of novel research approaches. Statistical averaging has its limitations and is unsuitable for the analysis of heterogeneity, as it masks diversity by homogenizing otherwise heterogeneous populations. Unfortunately, most researchers are unaware of alternative methods of analysis capable of accounting for individual variability. This paper describes a systems biology solution to data complexity through the application of parsimony phylogenetic analysis. Maximum parsimony (MP) provides a data-based modeling paradigm that will permit a priori stratification of the study cohort(s), better assessment of early diagnosis, prognosis, and treatment efficacy within each stratum, and a method that could be used to explore, identify and describe complex human patterning. PMID:22327551

  11. 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.

  12. 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.

  13. 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).

  14. Stabilization of collapsing scroll waves in systems with random heterogeneities

    NASA Astrophysics Data System (ADS)

    Weingard, Daniel; Blanco, Wilfredo; Steinbock, Oliver; Bertram, Richard

    2017-04-01

    In three-dimensional reaction-diffusion systems, excitation waves may form and rotate around a one-dimensional phase singularity called the filament. If the filament forms a closed curve, it will shrink over time and eventually collapse. However, filaments may pin to non-reactive objects present in the medium, reducing their rate of collapse or even allowing them to persist indefinitely. We use numerical simulations to study how different arrangements of non-reactive spheres affect the dynamics of circular filaments. As the filament contracts, it gets closer to and eventually touches and pins to objects in its path. This causes two possible behaviors. The filament can detach from the spheres in its path, slowing down the rate of contraction, or it can remain pinned to a collection of spheres. In general, more or larger spheres increase the chance that the filament remains pinned, but there are exceptions. It is possible for a small number of small spheres to support the filament and possible for the filament to pass through a large number of large spheres. Our work yields insights into the pinning of scroll waves in excitable tissue such as cardiac muscle, where scar tissue acts in a way similar to the non-reactive domains.

  15. 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

  16. Boron isotope exchange in a heterogeneous boron-boron fluoride system

    SciTech Connect

    Begak, O.Yu.; Fedorov, V.V.

    1988-11-01

    Studies have been made on exchange between /sup 10/B and /sup 11/B in heterogeneous systems containing finely divided amorphous boron and BF/sub 3/ gas. The kinetic and thermodynamic parameters have been examined. The self-diffusion coefficient for boron in amorphous boron has been determined at 973-1273 K.

  17. Higher order finite-time consensus protocol for heterogeneous multi-agent systems

    NASA Astrophysics Data System (ADS)

    Zhou, Yingjiang; Yu, Xinghuo; Sun, Changyin; Yu, Wenwu

    2015-02-01

    This paper studies the higher order finite-time consensus protocol for heterogeneous multi-agent systems (HMASs). By adding a power integrator method and using heterogeneous domination method, two kinds of consensus protocols are proposed with state feedback and output feedback, respectively. First, for the leaderless and leader-follower HMASs, the continuous finite-time consensus protocols are proposed. Then, by designing a finite-time observer, the output-feedback finite-time consensus protocol is developed. Finally, simulations are performed to illustrate the effectiveness of the theoretical results.

  18. Capturing the heterogeneity in systemic sclerosis with genome-wide expression profiling

    PubMed Central

    Sargent, Jennifer L; Whitfield, Michael L

    2011-01-01

    Heterogeneity in the clinical presentation and basic science findings of systemic sclerosis (SSc) has hindered the understanding of pathogenesis and development of effective treatments. Genome-wide profiling of SSc has measured this heterogeneity. Gene expression studies of diffuse SSc skin have shown reproducible, disease-specific gene expression signatures when compared with healthy controls and, surprisingly, disease-specific gene expression was found in both lesional and non-lesional skin. SSc-specific gene expression in peripheral blood cells and the lungs has also been demonstrated. Hypothesis-driven approaches that assess the contribution of individual pathways provide insight into the etiology of gene expression subsets. PMID:21790289

  19. Consensus of heterogeneous multi-agent systems with switching jointly-connected interconnection

    NASA Astrophysics Data System (ADS)

    Mo, Lipo; Niu, Yuguang; Pan, Tingting

    2015-06-01

    In this paper, the consensus problem of heterogeneous multi-agent systems with switching jointly-connected interconnection and a leader is considered. Firstly, by a model transformation, the original closed-loop system is turned into an equivalent system. And then, by applying the matrix theory and Lyapunov directed method, the convergence of the multi-agent systems is analyzed, a sufficient condition for consensus of systems is derived when the communication topologies are jointly-connected. Finally, simulation results are provided to demonstrate the effectiveness of presented results.

  20. 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.

  1. 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

  2. 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.

  3. SPORT: An Algorithm for Divisible Load Scheduling with Result Collection on Heterogeneous Systems

    NASA Astrophysics Data System (ADS)

    Ghatpande, Abhay; Nakazato, Hidenori; Beaumont, Olivier; Watanabe, Hiroshi

    Divisible Load Theory (DLT) is an established mathematical framework to study Divisible Load Scheduling (DLS). However, traditional DLT does not address the scheduling of results back to source (i. e., result collection), nor does it comprehensively deal with system heterogeneity. In this paper, the DLSRCHETS (DLS with Result Collection on HET-erogeneous Systems) problem is addressed. The few papers to date that have dealt with DLSRCHETS, proposed simplistic LIFO (Last In, First Out) and FIFO (First In, First Out) type of schedules as solutions to DLSRCHETS. In this paper, a new polynomial time heuristic algorithm, SPORT (System Parameters based Optimized Result Transfer), is proposed as a solution to the DLSRCHETS problem. With the help of simulations, it is proved that the performance of SPORT is significantly better than existing algorithms. The other major contributions of this paper include, for the first time ever, (a) the derivation of the condition to identify the presence of idle time in a FIFO schedule for two processors, (b) the identification of the limiting condition for the optimality of FIFO and LIFO schedules for two processors, and (c) the introduction of the concept of equivalent processor in DLS for heterogeneous systems with result collection.

  4. Automation of multi-agent control for complex dynamic systems in heterogeneous computational network

    NASA Astrophysics Data System (ADS)

    Oparin, Gennady; Feoktistov, Alexander; Bogdanova, Vera; Sidorov, Ivan

    2017-01-01

    The rapid progress of high-performance computing entails new challenges related to solving large scientific problems for various subject domains in a heterogeneous distributed computing environment (e.g., a network, Grid system, or Cloud infrastructure). The specialists in the field of parallel and distributed computing give the special attention to a scalability of applications for problem solving. An effective management of the scalable application in the heterogeneous distributed computing environment is still a non-trivial issue. Control systems that operate in networks, especially relate to this issue. We propose a new approach to the multi-agent management for the scalable applications in the heterogeneous computational network. The fundamentals of our approach are the integrated use of conceptual programming, simulation modeling, network monitoring, multi-agent management, and service-oriented programming. We developed a special framework for an automation of the problem solving. Advantages of the proposed approach are demonstrated on the parametric synthesis example of the static linear regulator for complex dynamic systems. Benefits of the scalable application for solving this problem include automation of the multi-agent control for the systems in a parallel mode with various degrees of its detailed elaboration.

  5. Syntheses, crystal structures, and magnetic properties of the oxalato-bridged mixed-valence complexes (FeII(bpm)3]2[FeIII2(ox)5].8H2O and FeII(bpm)3Na(H2O)2Fe(ox)(3).4H2O (bpm = 2,2'-bipyrimidine).

    PubMed

    Armentano, D; De Munno, G; Faus, J; Lloret, F; Julve, M

    2001-02-12

    The preparation and crystal structures of two oxalato-bridged FeII-FeIII mixed-valence compounds, [FeII(bpm)3]2[FeIII2(ox)5].8H2O (1) and FeII(bpm)3Na(H2O)2FeIII(ox)(3).4H2O (2) (bpm = 2,2'-bipyrimidine; ox = oxalate dianion) are reported here. Complex 1 crystallizes in the triclinic system, space group P1, with a = 10.998(2) A, b = 13.073(3) A, c = 13.308(3) A, alpha = 101.95(2) degrees, beta = 109.20(2) degrees, gamma = 99.89(2) degrees, and Z = 1. Complex 2 crystallizes in the monoclinic system, space group P2(1)/c, with a = 12.609(2) A, b = 19.670(5) A, c = 15.843(3) A, beta = 99.46(1) degrees, and Z = 4. The structure of complex 1 consists of centrosymmetric oxalato-bridged dinuclear high-spin iron(III) [Fe2(ox)5]2- anions, tris-chelated low-spin iron(II) [Fe(bpm)3]2+ cations, and lattice water molecules. The iron atoms are hexacoordinated: six oxygen atoms (iron(III)) from two bidentate and one bisbidentate oxalato ligands and six nitrogen atoms (iron(II)) from three bidentate bpm groups. The Fe(III)-O(ox) and Fe(II)-N(bpm) bond distances vary in the ranges 1.967(3)-2.099(3) and 1.967(4)-1.995(3) A, respectively. The iron(III)-iron(III) separation across the bridging oxalato is 5.449(2) A, whereas the shortest intermolecular iron(III)-iron(II) distance is 6.841(2) A. The structure of complex 2 consists of neutral heterotrinuclear Fe(bpm)2Na(H2O)2Fe(ox)3 units and water molecules of crystallization. The tris-chelated low-spin iron(II) ([Fe(bpm)3]2+) and high-spin iron(III) ([Fe(ox)3]3-) entities act as bidentate ligands (through two bpm-nitrogen and two oxalato-oxygen atoms, respectively) toward the univalent sodium cation, yielding the trinuclear (bpm)2Fe(II)-bpm-Na(I)-ox-Fe(III)(ox)2 complex. Two cis-coordinated water molecules complete the distorted octahedral surrounding of the sodium atom. The ranges of the Fe(II)-N(bpm) and Fe(III)-O(ox) bond distances [1.968(6)-1.993(5) and 1.992(6)-2.024(6) A, respectively] compare well with those observed in 1. The Na

  6. 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.

  7. Tungstate sulfuric acid (TSA)/KMnO4 as a novel heterogeneous system for rapid deoximation.

    PubMed

    Karami, Bahador; Montazerozohori, Morteza

    2006-09-28

    Neat chlorosulfonic acid reacts with anhydrous sodium tungstate to give tungstate sulfuric acid (TSA), a new dibasic inorganic solid acid in which two sulfuric acid molecules connect to a tungstate moiety via a covalent bond. A variety of oximes were oxidized to their parent carbonyl compounds under mild conditions with excellent yields in short times by a heterogeneous wet TSA/KMnO4 in dichloromethane system.

  8. Facile heterogenization of a cobalt catalyst via graphene adsorption: robust and versatile dihydrogen production systems.

    PubMed

    Eady, Shawn C; Peczonczyk, Sabrina L; Maldonado, Stephen; Lehnert, Nicolai

    2014-07-28

    A heterogeneous dihydrogen (H2) production system has been attained by simply soaking electrodes made from electro-deposited graphene on FTO plated glass in solutions of a cobalt bis(dithiolate) compound. The resulting electrodes are active in weakly acidic aqueous solutions (pH > 3), have relatively low overpotentials (0.37 V versus platinum), show high catalytic rates (TOF > 1000 s(-1)), and are resistant to degradation by dioxygen.

  9. 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.

  10. Harnessing Big Data to Represent 30-meter Spatial Heterogeneity in Earth System Models

    NASA Astrophysics Data System (ADS)

    Chaney, N.; Shevliakova, E.; Malyshev, S.; Van Huijgevoort, M.; Milly, C.; Sulman, B. N.

    2016-12-01

    Terrestrial land surface processes play a critical 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 (˜30 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 global 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. The state-of-the-art Geophysical Fluid Dynamics Laboratory (GFDL) land model is then used to simulate these tiles 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.

  11. 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.

  12. 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.

  13. Using heterogeneous wireless sensor networks in a telemonitoring system for healthcare.

    PubMed

    Corchado, Juan M; Bajo, Javier; Tapia, Dante I; Abraham, Ajith

    2010-03-01

    Ambient intelligence has acquired great importance in recent years and requires the development of new innovative solutions. This paper presents a distributed telemonitoring system, aimed at improving healthcare and assistance to dependent people at their homes. The system implements a service-oriented architecture based platform, which allows heterogeneous wireless sensor networks to communicate in a distributed way independent of time and location restrictions. This approach provides the system with a higher ability to recover from errors and a better flexibility to change their behavior at execution time. Preliminary results are presented in this paper.

  14. System-on-Chip Considerations for Heterogeneous Integration of CMOS and Fluidic Bio-Interfaces.

    PubMed

    Datta-Chaudhuri, Timir; Smela, Elisabeth; Abshire, Pamela A

    2016-04-21

    CMOS chips are increasingly used for direct sensing and interfacing with fluidic and biological systems. While many biosensing systems have successfully combined CMOS chips for readout and signal processing with passive sensing arrays, systems that co-locate sensing with active circuits on a single chip offer significant advantages in size and performance but increase the complexity of multi-domain design and heterogeneous integration. This emerging class of lab-on-CMOS systems also poses distinct and vexing technical challenges that arise from the disparate requirements of biosensors and integrated circuits (ICs). Modeling these systems must address not only circuit design, but also the behavior of biological components on the surface of the IC and any physical structures. Existing tools do not support the cross-domain simulation of heterogeneous lab-on-CMOS systems, so we recommend a two-step modeling approach: using circuit simulation to inform physics-based simulation, and vice versa. We review the primary lab-on-CMOS implementation challenges and discuss practical approaches to overcome them. Issues include new versions of classical challenges in system-on-chip integration, such as thermal effects, floor-planning, and signal coupling, as well as new challenges that are specifically attributable to biological and fluidic domains, such as electrochemical effects, non-standard packaging, surface treatments, sterilization, microfabrication of surface structures, and microfluidic integration. We describe these concerns as they arise in lab-on-CMOS systems and discuss solutions that have been experimentally demonstrated.

  15. System-on-Chip Considerations for Heterogeneous Integration of CMOS and Fluidic Bio-Interfaces.

    PubMed

    Datta-Chaudhuri, Timir; Smela, Elisabeth; Abshire, Pamela A

    2016-12-01

    CMOS chips are increasingly used for direct sensing and interfacing with fluidic and biological systems. While many biosensing systems have successfully combined CMOS chips for readout and signal processing with passive sensing arrays, systems that co-locate sensing with active circuits on a single chip offer significant advantages in size and performance but increase the complexity of multi-domain design and heterogeneous integration. This emerging class of lab-on-CMOS systems also poses distinct and vexing technical challenges that arise from the disparate requirements of biosensors and integrated circuits (ICs). Modeling these systems must address not only circuit design, but also the behavior of biological components on the surface of the IC and any physical structures. Existing tools do not support the cross-domain simulation of heterogeneous lab-on-CMOS systems, so we recommend a two-step modeling approach: using circuit simulation to inform physics-based simulation, and vice versa. We review the primary lab-on-CMOS implementation challenges and discuss practical approaches to overcome them. Issues include new versions of classical challenges in system-on-chip integration, such as thermal effects, floor-planning, and signal coupling, as well as new challenges that are specifically attributable to biological and fluidic domains, such as electrochemical effects, non-standard packaging, surface treatments, sterilization, microfabrication of surface structures, and microfluidic integration. We describe these concerns as they arise in lab-on-CMOS systems and discuss solutions that have been experimentally demonstrated.

  16. Heterogeneous systems biocatalysis; the path to the fabrication of self-sufficient artificial metabolic cells.

    PubMed

    López-Gallego, Fernando; Jackson, Eriene; Betancor, Lorena

    2017-09-26

    Industrial biocatalysis is playing a key role in the development of the global bio-economy that must change our current productive model to pair the socio-economical development with the preservation of our already harmed planet. The exploitation of isolated multi-enzyme systems and the discovery of novel biocatalytic activities are leading us to manufacture chemicals that were inaccessible through biological routes in the early past. These endeavors have been grouped in the concept of Systems biocatalysis. However, by using isolated biological machineries, fundamental features underlying the protein confinement found inside the living cells are missed. To re-gain these properties such concept can be expanded to a new concept; heterogeneous systems biocatalysis. This new concept is based on the fabrication of heterogeneous biocatalysts inspired by the spatial organization and compartmentalization that orchestrate metabolic pathways within cells. By assembling biological machineries (including enzymes and cofators) into artificial solid chassis, one can fabricate self-sufficient and robust cell-free systems able to catalyze orchestrated chemical processes. Furthermore, the confinement of enzymes and "artificial cofactor" inside solid materials has also attracted our attention since these self-sufficient systems exert de novo and non natural functionalities. Herein, we pursue going beyond immobilization of multi-enzyme systems, discussing only those enzymatic systems that have been co-immobilized with their cofactor or exogenous partners to enhance their cooperative action. In this article, we review the latest architectures developed to fabricate self-sufficient heterogeneous biocatalysts with application in chemical manufacturing, biosensing or energy production. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. Zirconium isotope evidence for the heterogeneous distribution of s-process materials in the solar system

    NASA Astrophysics Data System (ADS)

    Akram, W.; Schönbächler, M.; Bisterzo, S.; Gallino, R.

    2015-09-01

    A growing number of elements show well-resolved nucleosynthetic isotope anomalies in bulk-rock samples of solar system materials. In order to establish the occurrence and extent of such isotopic heterogeneities in Zr, and to investigate the origin of the widespread heterogeneities in our solar system, new high-precision Zr isotope data are reported for a range of primitive and differentiated meteorites. The majority of the carbonaceous chondrites (CV, CM, CO, CK) display variable ε96Zr values (⩽1.4) relative to the Earth. The data indicate the heterogeneous distribution of 96Zr-rich CAIs in these meteorites, which sampled supernova (SN) material that was likely synthesized by charged-particle reactions or neutron-captures. Other carbonaceous chondrites (CI, CB, CR), ordinary chondrites and eucrites display variable, well-resolved 96Zr excesses correlated with potential, not clearly resolved variations in 91Zr relative to the bulk-Earth and enstatite chondrites. This tentative correlation is supported by nucleosynthetic models and provides evidence for variable contributions of average solar system s-process material to different regions of the solar system, with the Earth representing the most s-process enriched material. New s-process model calculations indicate that this s-process component was produced in both low and intermediate mass asymptotic giant branch (AGB) stars. The isotopic heterogeneity pattern is different to the s-process signature resolved in a previous Zr leaching experiment, which was attributed to low mass AGB stars. The bulk-rock heterogeneity requires several nucleosynthetic sources, and therefore opposes the theory of the injection of material from a single source (e.g., supernova, AGB star) and argues for a selective dust-sorting mechanism within the solar nebula. Thermal processing of labile carrier phases is considered and, if correct, necessitates the destruction and removal of non-s-process material from the innermost solar system

  18. Soil Microbiome Is More Heterogeneous in Organic Than in Conventional Farming System.

    PubMed

    Lupatini, Manoeli; Korthals, Gerard W; de Hollander, Mattias; Janssens, Thierry K S; Kuramae, Eiko E

    2016-01-01

    Organic farming system and sustainable management of soil pathogens aim at reducing the use of agricultural chemicals in order to improve ecosystem health. Despite the essential role of microbial communities in agro-ecosystems, we still have limited understanding of the complex response of microbial diversity and composition to organic and conventional farming systems and to alternative methods for controlling plant pathogens. In this study we assessed the microbial community structure, diversity and richness using 16S rRNA gene next generation sequences and report that conventional and organic farming systems had major influence on soil microbial diversity and community composition while the effects of the soil health treatments (sustainable alternatives for chemical control) in both farming systems were of smaller magnitude. Organically managed system increased taxonomic and phylogenetic richness, diversity and heterogeneity of the soil microbiota when compared with conventional farming system. The composition of microbial communities, but not the diversity nor heterogeneity, were altered by soil health treatments. Soil health treatments exhibited an overrepresentation of specific microbial taxa which are known to be involved in soil suppressiveness to pathogens (plant-parasitic nematodes and soil-borne fungi). Our results provide a comprehensive survey on the response of microbial communities to different agricultural systems and to soil treatments for controlling plant pathogens and give novel insights to improve the sustainability of agro-ecosystems by means of beneficial microorganisms.

  19. Soil Microbiome Is More Heterogeneous in Organic Than in Conventional Farming System

    PubMed Central

    Lupatini, Manoeli; Korthals, Gerard W.; de Hollander, Mattias; Janssens, Thierry K. S.; Kuramae, Eiko E.

    2017-01-01

    Organic farming system and sustainable management of soil pathogens aim at reducing the use of agricultural chemicals in order to improve ecosystem health. Despite the essential role of microbial communities in agro-ecosystems, we still have limited understanding of the complex response of microbial diversity and composition to organic and conventional farming systems and to alternative methods for controlling plant pathogens. In this study we assessed the microbial community structure, diversity and richness using 16S rRNA gene next generation sequences and report that conventional and organic farming systems had major influence on soil microbial diversity and community composition while the effects of the soil health treatments (sustainable alternatives for chemical control) in both farming systems were of smaller magnitude. Organically managed system increased taxonomic and phylogenetic richness, diversity and heterogeneity of the soil microbiota when compared with conventional farming system. The composition of microbial communities, but not the diversity nor heterogeneity, were altered by soil health treatments. Soil health treatments exhibited an overrepresentation of specific microbial taxa which are known to be involved in soil suppressiveness to pathogens (plant-parasitic nematodes and soil-borne fungi). Our results provide a comprehensive survey on the response of microbial communities to different agricultural systems and to soil treatments for controlling plant pathogens and give novel insights to improve the sustainability of agro-ecosystems by means of beneficial microorganisms. PMID:28101080

  20. 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.

  1. Heterogeneous Molecular Systems for Photocatalytic CO2 Reduction with Water Oxidation.

    PubMed

    Liu, Xiao; Inagaki, Shinji; Gong, Jinlong

    2016-11-21

    Artificial photosynthesis-reduction of CO2 into chemicals and fuels with water oxidation in the presence of sunlight as the energy source-mimics natural photosynthesis in green plants, and is considered to have a significant part to play in future energy supply and protection of our environment. The high quantum efficiency and easy manipulation of heterogeneous molecular photosystems based on metal complexes enables them to act as promising platforms to achieve efficient conversion of solar energy. This Review describes recent developments in the heterogenization of such photocatalysts. The latest state-of-the-art approaches to overcome the drawbacks of low durability and inconvenient practical application in homogeneous molecular systems are presented. The coupling of photocatalytic CO2 reduction with water oxidation through molecular devices to mimic natural photosynthesis is also discussed.

  2. Cell-Specific Multifunctional Processing of Heterogeneous Cell Systems in a Single Laser Pulse Treatment

    PubMed Central

    Lukianova-Hleb, Ekaterina Y.; Mutonga, Martin B. G.; Lapotko, Dmitri O.

    2012-01-01

    Current methods of cell processing for gene and cell therapies use several separate procedures for gene transfer and cell separation or elimination, because no current technology can offer simultaneous multi-functional processing of specific cell sub-sets in highly heterogeneous cell systems. Using the cell-specific generation of plasmonic nanobubbles of different sizes around cell-targeted gold nanoshells and nanospheres, we achieved simultaneous multifunctional cell-specific processing in a rapid single 70 ps laser pulse bulk treatment of heterogeneous cell suspension. This method supported the detection of cells, delivery of external molecular cargo to one type of cells and the concomitant destruction of another type of cells without damaging other cells in suspension, and real-time guidance of the two above cellular effects. PMID:23167546

  3. Applying the Earth System Grid Security System in a Heterogeneous Environment of Data Access Services

    NASA Astrophysics Data System (ADS)

    Kershaw, Philip; Lawrence, Bryan; Lowe, Dominic; Norton, Peter; Pascoe, Stephen

    2010-05-01

    CEDA (Centre for Environmental Data Archival) based at STFC Rutherford Appleton Laboratory is host to the BADC (British Atmospheric Data Centre) and NEODC (NERC Earth Observation Data Centre) with data holdings of over half a Petabyte. In the coming months this figure is set to increase by over one Petabyte through the BADC's role as one of three data centres to host the CMIP5 (Coupled Model Intercomparison Project Phase 5) core archive of climate model data. Quite apart from the problem of managing the storage of such large volumes there is the challenge of collating the data together from the modelling centres around the world and enabling access to these data for the user community. An infrastructure to support this is being developed under the US Earth System Grid (ESG) and related projects bringing together participating organisations together in a federation. The ESG architecture defines Gateways, the web interfaces that enable users to access data and data serving applications organised into Data Nodes. The BADC has been working in collaboration with US Earth System Grid team and other partners to develop a security system to restrict access to data. This provides single sign-on via both OpenID and PKI based means and uses role based authorisation facilitated by SAML and OpenID based interfaces for attribute retrieval. This presentation will provide an overview of the access control architecture and look at how this has been implemented for CEDA. CEDA has developed an expertise in data access and information services over several years through a number of projects to develop and enhance these capabilities. Participation in CMIP5 comes at a time when a number of other software development activities are coming to fruition. New services are in the process of being deployed alongside services making up the system for ESG. The security system must apply access control across this heterogeneous environment of different data services and technologies. One strand

  4. 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.

  5. Considerations regarding system engineering in large scale projects with heterogeneous contexts

    NASA Astrophysics Data System (ADS)

    Cremonini, A.; Caiazzo, M.; Hayden, D.; Labate, M. G.; Oulgin, R.; Santander-Vela, J.

    2016-08-01

    In this paper we would like to share some considerations and lessons learned based on our direct experience as system engineer at the SKA project, with emphasis in the personal experiences of the first author. This is a very wide and ambitious program, which involves several stakeholders with a level of heterogeneity in cultural backgrounds, technological heritages, multidisciplinary interplays, motivations and competences without precedents. The role of the leading author is to amalgamate efforts in order to deliver the "MID telescope" and in that role, he has often discovered that, Systems Engineering means far more than purely a disciplined sets of processes.

  6. Phenotypic heterogeneity in the endothelium of the human vortex vein system.

    PubMed

    Yu, Paula K; Tan, Priscilla E Z; Cringle, Stephen J; McAllister, Ian L; Yu, Dao-Yi

    2013-10-01

    The vortex vein system is the drainage pathway for the choroidal circulation and serves an important function in the effective drainage of the exceptionally high blood flow from the choroidal circulation. As there are only 4-6 vortex veins, a large volume of blood must be drained from many choroidal veins into each individual vortex vein. The vortex vein system must also cope with passing through tissues of different rigidity and significant pressure gradient as it transverses from the intrao-cular to the extra-ocular compartments. However, little is known about how the vortex vein system works under such complex situations in both physiological and pathological condition. Endothelial cells play a vital role in other vascular systems, but they have not been studied in detail in the vortex vein system. The purpose of this study is to characterise the intracellular structures and morphology in both the intra-and extra-ocular regions of the human vortex vein system. We hypothesise the presence of endothelial phenotypic heterogeneity through the vortex vein system. The inferior temporal vortex vein system from human donor eyes were obtained and studied histologically using confocal microscopy. The f-actin cytoskeleton and nuclei were labelled using Alexa Fluor conjugated Phalloidin and YO-PRO-1. Eight regions of the vortex vein system were examined with the venous endothelium studied in detail with quantitative data obtained for endothelial cell and nuclei size and shape. Significant endothelial phenotypic heterogeneity was found throughout the vortex vein system with the most obvious differences observed between the ampulla and its downstream regions. Variation in the distribution pattern of smooth muscle cells, in particular the absence of smooth muscle cells around the ampulla, was noted. Our results suggest the presence of significantly different haemodynamic forces in different regions of the vortex vein system and indicate that the vortex vein system may play

  7. 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

  8. Regional heterogeneity of endothelial cells in the porcine vortex vein system.

    PubMed

    Tan, Priscilla Ern Zhi; Yu, Paula K; Cringle, Stephen J; Morgan, William H; Yu, Dao-Yi

    2013-09-01

    The aim of this study was to investigate whether region-dependent endothelial heterogeneity is present within the porcine vortex vein system. The superior temporal vortex vein in young adult pig eyes were dissected out and cannulated. The intact vortex vein system down to the choroidal veins was then perfused with labels for f-actin and nucleic acid. The endothelial cells within the choroidal veins, pre-ampulla, anterior portion of the ampulla, mid-ampulla, posterior portion of the ampulla, post-ampulla, intra-scleral canal and the extra-ocular vortex vein regions were studied in detail using a confocal microscopy technique. The endothelial cell and nuclei length, width, area and perimeter were measured and compared between the different regions. Significant regional differences in the endothelial cell and nuclei length, width, area and perimeter were observed throughout the porcine vortex vein system. Most notably, very narrow and elongated endothelia were found in the post-ampulla region. A lack of smooth muscle cells was noted in the ampulla region compared to other regions. Heterogeneity in endothelial cell morphology is present throughout the porcine vortex vein system and there is a lack of smooth muscle cells in the ampulla region. This likely reflects the highly varied haemodynamic conditions and potential blood flow control mechanisms in different regions of the vortex vein system. Copyright © 2013 Elsevier Inc. All rights reserved.

  9. 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].

  10. Heterogeneity of D-Serine Distribution in the Human Central Nervous System

    PubMed Central

    Suzuki, Masataka; Imanishi, Nobuaki; Mita, Masashi; Hamase, Kenji; Aiso, Sadakazu

    2017-01-01

    D-serine is an endogenous ligand for N-methyl-D-aspartate glutamate receptors. Accumulating evidence including genetic associations of D-serine metabolism with neurological or psychiatric diseases suggest that D-serine is crucial in human neurophysiology. However, distribution and regulation of D-serine in humans are not well understood. Here, we found that D-serine is heterogeneously distributed in the human central nervous system (CNS). The cerebrum contains the highest level of D-serine among the areas in the CNS. There is heterogeneity in its distribution in the cerebrum and even within the cerebral neocortex. The neocortical heterogeneity is associated with Brodmann or functional areas but is unrelated to basic patterns of cortical layer structure or regional expressional variation of metabolic enzymes for D-serine. Such D-serine distribution may reflect functional diversity of glutamatergic neurons in the human CNS, which may serve as a basis for clinical and pharmacological studies on D-serine modulation. PMID:28604057

  11. Fluctuations in the time variable and dynamical heterogeneity in glass-forming systems.

    PubMed

    Avila, Karina E; Castillo, Horacio E; Parsaeian, Azita

    2013-10-01

    We test a hypothesis for the origin of dynamical heterogeneity in slowly relaxing systems, namely that it emerges from soft (Goldstone) modes associated with a broken continuous symmetry under time reparametrizations. We do this by constructing coarse grained observables and decomposing the fluctuations of these observables into transverse components, which are associated with the postulated time-fluctuation soft modes, and a longitudinal component, which represents the rest of the fluctuations. Our test is performed on data obtained in simulations of four models of structural glasses. As the hypothesis predicts, we find that the time reparametrization fluctuations become increasingly dominant as temperature is lowered and timescales are increased. More specifically, the ratio between the strengths of the transverse fluctuations and the longitudinal fluctuations grows as a function of the dynamical susceptibility, χ(4), which represents the strength of the dynamical heterogeneity; and the correlation volumes for the transverse fluctuations are approximately proportional to those for the dynamical heterogeneity, while the correlation volumes for the longitudinal fluctuations remain small and approximately constant.

  12. Developing Verification Systems for Building Information Models of Heritage Buildings with Heterogeneous Datasets

    NASA Astrophysics Data System (ADS)

    Chow, L.; Fai, S.

    2017-08-01

    The digitization and abstraction of existing buildings into building information models requires the translation of heterogeneous datasets that may include CAD, technical reports, historic texts, archival drawings, terrestrial laser scanning, and photogrammetry into model elements. In this paper, we discuss a project undertaken by the Carleton Immersive Media Studio (CIMS) that explored the synthesis of heterogeneous datasets for the development of a building information model (BIM) for one of Canada's most significant heritage assets - the Centre Block of the Parliament Hill National Historic Site. The scope of the project included the development of an as-found model of the century-old, six-story building in anticipation of specific model uses for an extensive rehabilitation program. The as-found Centre Block model was developed in Revit using primarily point cloud data from terrestrial laser scanning. The data was captured by CIMS in partnership with Heritage Conservation Services (HCS), Public Services and Procurement Canada (PSPC), using a Leica C10 and P40 (exterior and large interior spaces) and a Faro Focus (small to mid-sized interior spaces). Secondary sources such as archival drawings, photographs, and technical reports were referenced in cases where point cloud data was not available. As a result of working with heterogeneous data sets, a verification system was introduced in order to communicate to model users/viewers the source of information for each building element within the model.

  13. 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. © The Author(s) 2014.

  14. 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.

  15. Computer investigation of the percolation processes in two- and three-dimensional systems with heterogeneous internal structure

    NASA Astrophysics Data System (ADS)

    Bagnich, S. A.; Konash, A. V.

    2003-04-01

    The results of computer investigation of the percolation processes in two- and three-dimensional heterogeneous lattices are presented. The heterogeneous condition is simulated by a random distribution of obstacles differing in size and number. The influence of obstacles on the parameters (critical concentration, average number of sites in finite clusters, percolation probability, critical exponents, and fractal and spectral dimensions of a percolation cluster) characterizing the percolation in the system is analyzed. It is demonstrated that all these parameters essentially depend on features of the heterogeneous internal structure (linear size and relative area of the obstacles) of the system.

  16. Diuron degradation in irradiated, heterogeneous iron/oxalate systems: the rate-determining step.

    PubMed

    Mazellier, P; Sulzberger, B

    2001-08-15

    The purpose of this study was to examine the various factors that control the kinetics of diuron degradation in irradiated, aerated suspensions containing goethite (alpha-FeOOH) and oxalate, in the following denoted as heterogeneous photo-Fenton systems. In these systems, attack by hydroxyl radicals (HO.) was the only pathway of diuron degradation. Studies were conducted in systems containing initially 80 or 200 mg L(-1) goethite (corresponding to 0.9 or 2.25 mM total iron) and 20, 50, 75, 100, 200, and 400 microM oxalate at 3 < or = pH < or = 6. Both oxalate concentration and pH greatly affected the rate of light-induced diuron transformation. In the presence of initial 200 microM oxalate, the rate of diuron degradation was maximal at pH 4, coinciding with the maximal extent of oxalate adsorption on the surface of goethite. At pH 4,the rate of light-induced diuron degradation increased with increasing oxalate concentration, reaching a plateau at initial 200 microM oxalate, i.e., at the oxalate solution concentration at which the extent of oxalate adsorption on the surface of goethite reached a maximum. These experimental results suggest that the rate of Fe(II)(aq) formation through photochemical reductive dissolution of goethite, with oxalate acting as electron donor, determines the kinetics of diuron degradation in these heterogeneous photo-Fenton systems.

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

    PubMed

    Baniassadi, M; Safdari, M; Garmestani, H; Ahzi, S; Geubelle, P H; 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.

  18. Standardized terminological services enabling semantic interoperability between distributed and heterogeneous systems.

    PubMed

    Ingenerf, J; Reiner, J; Seik, B

    2001-12-01

    The interconnection of heterogeneous computer applications in medicine raises the issue of semantic interoperability, going beyond traditional approaches of terminological standardization in basically three aspects. First, the variety of medical vocabularies that currently coexist in different domains is a major barrier for the integration of autonomously developed applications. Fortunately, with the Unified Medical Language System (UMLS) there are machine-readable terminological sources that cover and integrate most of the existing medical vocabularies. Second, the exchanged data need to be processed by a machine for different purposes like patient data integration, access to literature and knowledge bases as well as clinical audit and research. Medical vocabularies provided as passive dictionaries are no longer sufficient. Software system developers should take advantage of terminological services for refining user queries, for mapping the user's terms to appropriate medical vocabularies etc. Third, the services should be accessible uniformly and transparently. In the CORBAmed initiative a proposal for a standardized interface for querying and accessing computerized medical terminology resources was created. Based on the mentioned principles the MUSTANG system (Medical UMLS based Terminology Server for Authoring, Navigating and Guiding the Retrieval to Heterogeneous Knowledge Sources) has been developed. It is implemented on a Windows NT platform using the ORACLE database management and development software. The terminological services are accessible via multiple interfaces. The MUSTANG-System and the experiences with using terminological services in practice are described. Opposed to other levels of standardization like syntactical message standards there is much more a hesitation in the use of standardized terminology.

  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. Modeling Integration and Reuse of Heterogeneous Terminologies in Faceted Browsing Systems

    PubMed Central

    Harris, Daniel R.

    2017-01-01

    We integrate heterogeneous terminologies into our category-theoretic model of faceted browsing and show that existing terminologies and vocabularies can be reused as facets in a cohesive, interactive system. Commonly found in online search engines and digital libraries, faceted browsing systems depend upon one or more taxonomies which outline the structure and content of the facets available for user interaction. Controlled vocabularies or terminologies are often externally curated and are available as a reusable resource across systems. We demonstrated previously that category theory can abstractly model faceted browsing in a way that supports the development of interfaces capable of reusing and integrating multiple models of faceted browsing. We extend this model by illustrating that terminologies can be reused and integrated as facets across systems with examples from the biomedical domain.

  1. Application of heterogeneous multiple camera system with panoramic capabilities in a harbor environment

    NASA Astrophysics Data System (ADS)

    Schwering, Piet B. W.; Lensen, Henk A.; van den Broek, Sebastiaan P.; den Hollander, Richard J. M.; van der Mark, Wannes; Bouma, Henri; Kemp, Rob A. W.

    2009-09-01

    In a harbor environment threats like explosives-packed rubber boats, mine-carrying swimmers and divers must be detected in an early stage. This paper describes the integration and use of a heterogeneous multiple camera system with panoramic observation capabilities for detecting these small vessels in the Den Helder New Harbor in the Netherlands. Results of a series of experiments with different targets are presented. An outlook to a future sensor package containing panoramic vision is discussed. We also investigated several aspects of the use of electro-optical systems. As for classification, this paper concentrates on discriminating classes of small vessels with different electro-optical systems (visual and infrared) as part of the larger process involving an operator. It addresses both selection of features (based on shape and texture) and ways of using these in a system to assess threats. Results are presented on data recorded in coastal and harbor environments for several small targets.

  2. 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.

  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. Anomalous diffusion and transport in heterogeneous systems separated by a membrane

    NASA Astrophysics Data System (ADS)

    Lenzi, E. K.; Ribeiro, H. V.; Tateishi, A. A.; Zola, R. S.; Evangelista, L. R.

    2016-11-01

    Diffusion of particles in a heterogeneous system separated by a semipermeable membrane is investigated. The particle dynamics is governed by fractional diffusion equations in the bulk and by kinetic equations on the membrane, which characterizes an interface between two different media. The kinetic equations are solved by incorporating memory effects to account for anomalous diffusion and, consequently, non-Debye relaxations. A rich variety of behaviours for the particle distribution at the interface and in the bulk may be found, depending on the choice of characteristic times in the boundary conditions and on the fractional index of the modelling equations.

  5. TOPICAL REVIEW: Statistical mechanics of socio-economic systems with heterogeneous agents

    NASA Astrophysics Data System (ADS)

    DeMartino, Andrea; Marsili, Matteo

    2006-10-01

    We review the statistical mechanics approach to the study of the emerging collective behaviour of systems of heterogeneous interacting agents. The general framework is presented through examples in such contexts as ecosystem dynamics and traffic modelling. We then focus on the analysis of the optimal properties of large random resource-allocation problems and on Minority Games and related models of speculative trading in financial markets, discussing a number of extensions including multi-asset models, majority games and models with asymmetric information. Finally, we summarize the main conclusions and outline the major open problems and limitations of the approach.

  6. 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.

  7. Interfacial tension in cooled heterogeneous liquid acetonitrile-ethyl acetate-isopropanol-water-phenol systems

    NASA Astrophysics Data System (ADS)

    Rudakov, O. B.; Khorokhordina, E. A.; Preobrazhenskii, M. A.

    2017-04-01

    It is found that the tension at the interfacial boundary of liquid phases formed by mixtures of acetonitrile-ethyl acetate-isopropanol (85 : 15 : 0 and 80 : 15 : 5 vol/vol/vol %) and water at 263 K falls exponentially as the concentration of phenols grows within 0-1 mg/mL. It is shown that the relatively low values of interfacial tension (11-32 mN/m) observed in cooled heterogeneous systems promote the redistribution of phenols between two liquid phases.

  8. Distributed formation output regulation of switching heterogeneous multi-agent systems

    NASA Astrophysics Data System (ADS)

    Wang, Xiaoli

    2013-11-01

    In this article, the distributed formation output regulation problem of linear heterogeneous multi-agent systems with uncertainty under switching topology is considered. It is a generalised framework for multi-agent coordination problems, which contains or concerns a variety of important multi-agent problems in a quite unified way. Its background includes active leader following formation for the agents to maintain desired relative distances and orientations to the leader with a predefined trajectory, and multi-agent formation with environmental inputs. With the help of canonical internal model we design a distributed dynamic output feedback to handle the distributed formation output regulation problem.

  9. Decolorization of Reactive Red 2 by advanced oxidation processes: Comparative studies of homogeneous and heterogeneous systems.

    PubMed

    Wu, Chung-Hsin; Chang, Chung-Liang

    2006-02-06

    This study investigated the decolorization of the Reactive Red 2 in water using advanced oxidation processes (AOPs): UV/TiO2, UV/SnO2, UV/TiO2+SnO2, O3, O3+MnO2, UV/O3 and UV/O3+TiO2+SnO2. Kinetic analyses indicated that the decolorization rates of Reactive Red 2 could be approximated as pseudo-first-order kinetics for both homogeneous and heterogeneous systems. The decolorization rate at pH 7 exceeded pH 4 and 10 in UV/TiO2 and UV/TiO2+SnO2 systems, respectively. However, the rate constants in the systems (including O3) demonstrated the order of pH 10>pH 7>pH 4. The UV/TiO2+SnO2 and O3+MnO2 systems exhibited a greater decolorization rate than the UV/TiO2 and O3 systems, respectively. Additionally, the promotion of rate depended on pH. The variation of dye concentration influenced the decolorization efficiency of heterogeneous systems more significant than homogeneous systems. Experimental results verified that decolorization and desulfuration occurred at nearly the same rate. Moreover, the decolorization rate constants at pH 7 in various systems followed the order of UV/O3 > or = O3+MnO2 > or = UV/O3+TiO2+SnO2 > O3 > UV/TiO2+SnO2 > or = UV/TiO2 > UV/SnO2.

  10. Implications of non-equilibrium transport in heterogeneous reactive barrier systems: evidence from laboratory denitrification experiments.

    PubMed

    Herbert, Roger B

    2011-04-01

    Organic substrates in reactive barrier systems are often heterogeneous material mixtures with relatively large contrasts in hydraulic conductivity and porosity over short distances. These short-range variations in material properties imply that preferential flow paths and diffusion between regions of higher and lower hydraulic conductivity may be important for treatment efficiency. This paper presents the results of a laboratory column experiment where denitrification is investigated using a heterogeneous reactive substrate (sawdust mixed with sewage sludge). Displacement experiments with a non-reactive solute at three different flow rates are used to estimate transport parameters using a dual porosity non-equilibrium model. Parameter estimation from breakthrough curves produced relatively consistent values for the fraction of the porosity consisting of mobile water (β) and the mass transfer coefficient (α), with average values of 0.27 and 0.42 d(-1), respectively. The column system removes >95% of the influent nitrate at low and medium flow, but only 50-75% of the influent nitrate at high flow, suggesting that denitrification kinetics and diffusive mass transfer rates are limiting the degree of treatment at lower hydraulic residence times. Reactive barrier systems containing dual porosity media must therefore consider mass transfer times in their design; this is often most easily accommodated by adjusting flowpath length. Copyright © 2010 Elsevier B.V. All rights reserved.

  11. Implications of non-equilibrium transport in heterogeneous reactive barrier systems: Evidence from laboratory denitrification experiments

    NASA Astrophysics Data System (ADS)

    Herbert, Roger B., Jr.

    2011-04-01

    Organic substrates in reactive barrier systems are often heterogeneous material mixtures with relatively large contrasts in hydraulic conductivity and porosity over short distances. These short-range variations in material properties imply that preferential flow paths and diffusion between regions of higher and lower hydraulic conductivity may be important for treatment efficiency. This paper presents the results of a laboratory column experiment where denitrification is investigated using a heterogeneous reactive substrate (sawdust mixed with sewage sludge). Displacement experiments with a non-reactive solute at three different flow rates are used to estimate transport parameters using a dual porosity non-equilibrium model. Parameter estimation from breakthrough curves produced relatively consistent values for the fraction of the porosity consisting of mobile water (β) and the mass transfer coefficient (α), with average values of 0.27 and 0.42 d - 1 , respectively. The column system removes > 95% of the influent nitrate at low and medium flow, but only 50-75% of the influent nitrate at high flow, suggesting that denitrification kinetics and diffusive mass transfer rates are limiting the degree of treatment at lower hydraulic residence times. Reactive barrier systems containing dual porosity media must therefore consider mass transfer times in their design; this is often most easily accommodated by adjusting flowpath length.

  12. 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

  13. 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.

  14. 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

  15. 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.

  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. 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.

  18. Development of a Heterogeneous sUAS High-Accuracy Positional Flight Data Acquisition System

    NASA Technical Reports Server (NTRS)

    McSwain, Robert G.; Grosveld, Ferdinand W.

    2016-01-01

    Recently, a heterogeneous FDAS, consisting of a diverse range of instruments was developed to support acoustic flight research programs at NASA Langley Research Center. In addition to a conventional GPS to measure latitude, longitude and altitude, the FDAS also utilizes a small, light-weight, low-cost DGPS system to obtain centimeter accuracy to measure the distance traveled by sound from a sUAS vehicle to a microphone on the ground. Acoustic flight testing using the FDAS installed on several different sUAS platforms has been conducted in support of the NASA CAS DELIVER and ERA ITD projects (Reference 1). The first FDAS prototype was assembled and implemented in the acoustic/flight measurement system in December 2014 to support DELIVER acoustic flight tests. Evaluation of the system performance and results from the data analyses were used to further test, develop and enhance the FDAS over a six-month period to support acoustic flight research for the ERA.

  19. 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.

  20. New device to measure dynamic intrusion/extrusion cycles of lyophobic heterogeneous systems

    NASA Astrophysics Data System (ADS)

    Guillemot, Ludivine; Galarneau, Anne; Vigier, Gérard; Abensur, Thierry; Charlaix, Élisabeth

    2012-10-01

    Lyophobic heterogeneous systems (LHS) are made of mesoporous materials immersed in a non-wetting liquid. One application of LHS is the nonlinear damping of high frequency vibrations. The behaviour of LHS is characterized by P - ΔV cycles, where P is the pressure applied to the system, and ΔV its volume change due to the intrusion of the liquid into the pores of the material, or its extrusion out of the pores. Very few dynamic studies of LHS have been performed until now. We describe here a new apparatus that allows us to carry out dynamic intrusion/extrusion cycles with various liquid/porous material systems, controlling the temperature from ambient to 120 °C and the frequency from 0.01 to 20 Hz. We show that for two LHS: water/MTS and Galinstan/CPG, the energy dissipated during one cycle depends very weakly on the cycle frequency, in strong contrast to conventional dampers.

  1. 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

  2. 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.

  3. 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.

  4. An Energy-Efficient Underground Localization System Based on Heterogeneous Wireless Networks

    PubMed Central

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

    2015-01-01

    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. PMID:26016918

  5. 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.

  6. 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.

  7. High Bee and Wasp Diversity in a Heterogeneous Tropical Farming System Compared to Protected Forest

    PubMed Central

    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. PMID:23300598

  8. 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.

  9. Gamma ray scanner systems for nondestructive assay of heterogeneous waste barrels

    SciTech Connect

    Martz, H.E.; Decman, B.J.; Roberson, G.P.; Levai, F.

    1997-03-25

    Traditional gamma safeguards measurements have usually been performed using a segmented gamma scanning (SGS) system. The accuracy of this technique relies on the assumption that the sample matrix and the activity are both uniform for a segment. Waste barrels are often highly heterogeneous, span a wide range of composition and matrix type. The primary sources of error are all directly or indirectly related to a non-uniform measurement response associated with unknown radioactive source spatial distribution and heterogeneity of the matrix. These errors can be significantly reduced by some imaging techniques that measure exact spatial locations of sources and attenuation maps. In this paper we describe a joint R&D effort between the Lawrence Livermore National Laboratory (LLNL) and the Institute of Nuclear Techniques (INT) of the Technical University, Budapest, to compare results obtained by two different gamma-ray nondestructive assay (NDA) systems used for imaging waste barrels. The basic principles are the same, but the approaches are different. Key factors to judge the adequacy of a method are the detection limit and the accuracy. Test drums representing waste to be measured are used to determine basic parameters of these techniques.

  10. 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.

  11. Good coupling for the multiscale patch scheme on systems with microscale heterogeneity

    NASA Astrophysics Data System (ADS)

    Bunder, J. E.; Roberts, A. J.; Kevrekidis, I. G.

    2017-05-01

    Computational simulation of microscale detailed systems is frequently only feasible over spatial domains much smaller than the macroscale of interest. The 'equation-free' methodology couples many small patches of microscale computations across space to empower efficient computational simulation over macroscale domains of interest. Motivated by molecular or agent simulations, we analyse the performance of various coupling schemes for patches when the microscale is inherently 'rough'. As a canonical problem in this universality class, we systematically analyse the case of heterogeneous diffusion on a lattice. Computer algebra explores how the dynamics of coupled patches predict the large scale emergent macroscale dynamics of the computational scheme. We determine good design for the coupling of patches by comparing the macroscale predictions from patch dynamics with the emergent macroscale on the entire domain, thus minimising the computational error of the multiscale modelling. The minimal error on the macroscale is obtained when the coupling utilises averaging regions which are between a third and a half of the patch. Moreover, when the symmetry of the inter-patch coupling matches that of the underlying microscale structure, patch dynamics predicts the desired macroscale dynamics to any specified order of error. The results confirm that the patch scheme is useful for macroscale computational simulation of a range of systems with microscale heterogeneity.

  12. Quadrupole-Echo Techniques in Multiple-Quantum-Filtered NMR Spectroscopy of Heterogeneous Systems

    NASA Astrophysics Data System (ADS)

    Eliav, U.; Navon, G.

    Multiple-quantum-filtered quadrupole-echo pulse sequences for spin I = 1 and I = {3}/{2} are suggested. A general condition for obtaining simultaneously Zeeman and quadrupolar echo is formulated. A theoretical analysis of the various pulse sequences was performed on the basis of second-order perturbation approximation of the Liouville equation for the density matrix. The extent of refocusing as a function of the ratio of the residual quadrupolar interaction and the relaxation rates was calculated. Experimental results are presented for 2H and 23Na in cartilage as an example of a heterogeneous system with residual quadrupolar interaction. The difference between relaxation times measured by the multiple-quantum-filtered echo techniques and those measured by conventional multiple-quantum-filtered NMR spectroscopy is a simple diagnostic of anisotropic motion that leads to a residual quadrupolar interaction. The results of the echo experiments are compared with the relaxation times computed on the basis of lineshape analysis of double-quantum-filtered spectra of a heterogeneous system.

  13. 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.

  14. Phosphorescence lifetime analysis with a quadratic programming algorithm for determining quencher distributions in heterogeneous systems.

    PubMed Central

    Vinogradov, S A; Wilson, D F

    1994-01-01

    A new method for analysis of phosphorescence lifetime distributions in heterogeneous systems has been developed. This method is based on decomposition of the data vector to a linearly independent set of exponentials and uses quadratic programming principles for x2 minimization. Solution of the resulting algorithm requires a finite number of calculations (it is not iterative) and is computationally fast and robust. The algorithm has been tested on various simulated decays and for analysis of phosphorescence measurements of experimental systems with descrete distributions of lifetimes. Critical analysis of the effect of signal-to-noise on the resolving capability of the algorithm is presented. This technique is recommended for resolution of the distributions of quencher concentration in heterogeneous samples, of which oxygen distributions in tissue is an important example. Phosphors of practical importance for biological oxygen measurements: Pd-meso-tetra (4-carboxyphenyl) porphyrin (PdTCPP) and Pd-meso-porphyrin (PdMP) have been used to provide experimental test of the algorithm. PMID:7858142

  15. Hot News Recommendation System from Heterogeneous Websites Based on Bayesian Model

    PubMed Central

    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. PMID:25093207

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

    PubMed Central

    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.

    2015-01-01

    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. PMID:25660033

  17. 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.

  18. 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

  19. Small scale laboratory design investigation of leakage of gaseous CO2 through heterogeneous subsurface system

    NASA Astrophysics Data System (ADS)

    Basirat, F.; Sharma, P.; Niemi, A.; Fagerlund, F.

    2012-04-01

    movement and detectability of the CO2. Our laboratory experiment is designed and implemented for measuring CO2 distribution in time and space through the heterogeneous porous material. The CO2 concentrations through the domain are measured by using sensitive gas sensors. To better understand the consequences of CO2 leakage and how it can be detected, this study presents a conceptual model together with the design and setup of an experimental system to understand the transport, trapping and detectability of gaseous CO2 in a heterogeneous shallow geological system.

  20. Direction-sensitive smart monitoring of structures using heterogeneous smartphone sensor data and coordinate system transformation

    NASA Astrophysics Data System (ADS)

    Ozer, Ekin; Feng, Maria Q.

    2017-04-01

    Mobile, heterogeneous, and smart sensor networks produce pervasive structural health monitoring (SHM) information. With various embedded sensors, smartphones have emerged to innovate SHM by empowering citizens to serve as sensors. By default, smartphones meet the fundamental smart sensor criteria, thanks to the built-in processor, memory, wireless communication units and mobile operating system. SHM using smartphones, however, faces technical challenges due to citizen-induced uncertainties, undesired sensor-structure integration, and lack of control over the sensing platform. Previously, the authors presented successful applications of smartphone accelerometers for structural vibration measurement and proposed a monitoring framework under citizen-induced spatiotemporal uncertainties. This study aims at extending the capabilities of smartphone-based SHM with a special focus on the lack of control over the sensor (i.e., the phone) positioning by citizens resulting in unknown sensor orientations. Using smartphone gyroscope, accelerometer, and magnetometer; instantaneous sensor orientation can be obtained with respect to gravitational and magnetic north directions. Using these sensor data, mobile operating system frameworks return processed features such as attitude and heading that can be used to correct misaligned sensor signals. For this purpose, a coordinate transformation procedure is proposed and illustrated on a two-story laboratory structural model and real-scale bridges with various sensor positioning examples. The proposed method corrects the sensor signals by tracking their orientations and improves measurement accuracy. Moreover, knowing structure’s coordinate system a priori, even the data from arbitrarily positioned sensors can automatically be transformed to the structural coordinates. In addition, this paper also touches some secondary mobile and heterogeneous data issues including imperfect sampling and geolocation services. The coordinate system

  1. Dynamic heterogeneity: a framework to promote ecological integration and hypothesis generation in urban systems

    Treesearch

    S. T. A. Pickett; M. L. Cadenasso; E. J. Rosi-Marshall; Ken Belt; P. M. Groffman; Morgan Grove; E. G. Irwin; S. S. Kaushal; S. L. LaDeau; C. H. Nilon; C. M. Swan; P. S. Warren

    2016-01-01

    Urban areas are understood to be extraordinarily spatially heterogeneous. Spatial heterogeneity, and its causes, consequences, and changes, are central to ecological science. The social sciences and urban design and planning professions also include spatial heterogeneity as a key concern. However, urban ecology, as a pursuit that integrates across these disciplines,...

  2. Metaheuristic Based Scheduling Meta-Tasks in Distributed Heterogeneous Computing Systems

    PubMed Central

    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. PMID:22346701

  3. 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.

  4. Gamma ray scanner systems for nondestructive assay of heterogeneous waste barrels

    SciTech Connect

    Martz, H.E.; Roberson, G.P.; Decman, D.J.; Camp, D.C.; Levai, F.

    1997-08-01

    Traditional gamma measurement errors are related to non-uniform measurement responses associated with unknown radioactive source and matrix material distributions. These errors can be reduced by application of tomographic techniques that measure these distributions. LLNL has developed two tomographic-based waste assay systems. They use external radioactive sources and tomography-protocol to map the attenuation within a waste barrel as a function of mono-energetic gamma-ray energy in waste containers. Passive tomography is used to localize and identify specific radioactive waste contents within the same waste containers. Reconstruction of the passive data via the active images allows internal waste radioactivities in a barrel to be corrected for any overlying heterogeneous materials, thus yielding an absolute assay of the waste radioactivities. Calibration of both systems requires only point source measurements and are independent of matrix materials.

  5. Complex Nonlinear Dynamic System of Oligopolies Price Game with Heterogeneous Players Under Noise

    NASA Astrophysics Data System (ADS)

    Liu, Feng; Li, Yaguang

    A nonlinear four oligopolies price game with heterogeneous players, that are boundedly rational and adaptive, is built using two different special demand costs. Based on the theory of complex discrete dynamical system, the stability and the existing equilibrium point are investigated. The complex dynamic behavior is presented via bifurcation diagrams, the Lyapunov exponents to show equilibrium state, bifurcation and chaos with the variation in parameters. As disturbance is ubiquitous in economic systems, this paper focuses on the analysis of delay feedback control method under noise circumstances. Stable dynamics is confirmed to depend mainly on the low price adjustment speed, and if all four players have limited opportunities to stabilize the market, the new adaptive player facing profits of scale are found to be higher than the incumbents of bounded rational.

  6. Real-Time Scheduling in Heterogeneous Systems Considering Cache Reload Time Using Genetic Algorithms

    NASA Astrophysics Data System (ADS)

    Miryani, Mohammad Reza; Naghibzadeh, Mahmoud

    Since optimal assignment of tasks in a multiprocessor system is, in almost all practical cases, an NP-hard problem, in recent years some algorithms based on genetic algorithms have been proposed. Some of these algorithms have considered real-time applications with multiple objectives, total tardiness, completion time, etc. Here, we propose a suboptimal static scheduler of nonpreemptable tasks in hard real-time heterogeneous multiprocessor systems considering time constraints and cache reload time. The approach makes use of genetic algorithm to minimize total completion time and number of processors used, simultaneously. One important issue which makes this research different from previous ones is cache reload time. The method is implemented and the results are compared against a similar method.

  7. ESR ST study of hydroxyl radical generation in wet peroxide system catalyzed by heterogeneous ruthenium.

    PubMed

    Rokhina, Ekaterina V; Golovina, Elena A; As, Henk van; Virkutyte, Jurate

    2009-09-01

    Ru-based catalysts gained popularity because of their applicability for a variety of processes, including carbon monoxide oxidation, wet air catalytic oxidation and wastewater treatment. The focus of a current study was generation of hydroxyl radicals in the wet peroxide system catalyzed by heterogeneous ruthenium, spin-trapped by DEPMPO and DIPPMPO by means of electron spin resonance spin-trapping technique (ESR ST). The mechanism of free radicals formation was proposed via direct cleavage of hydrogen peroxide over ruthenium active sites. The chemical reactions occurring in the system were introduced according to the experimental results. Also, radical production rate was assessed based on concentration changes of species involved in the bulk liquid phase oxidation.

  8. Modeling heterogeneous and fractured reservoirs with inverse methods based on iterated function systems

    SciTech Connect

    Long, J.C.S.; Doughty, C.; Hestir, K.; Martel, S.

    1992-05-01

    Fractured and heterogeneous reservoirs are complex and difficult to characterize. In many cases, the modeling approaches used for making predictions of behavior in such reservoirs have been unsatisfactory. In this paper we describe a new modeling approach which results in a model that has fractal-like qualities. This is an inverse approach which uses observations of reservoir behavior to create a model that can reproduce observed behavior. The model is described by an iterated function system (IFS) that creates a fractal-like object that can be mapped into a conductivity distribution. It may be possible to identify subclasses of Iterated Function Systems which describe geological facies. By limiting the behavior-based search for an IFS to the geologic subclasses, we can condition the reservoir model on geologic information. This technique is under development, but several examples provide encouragement for eventual application to reservoir prediction.

  9. 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.

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

    PubMed

    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.

  11. 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.

  12. Representing Soil Moisture Heterogeneity in the "Super-Parameterized" Community Earth System Model

    NASA Astrophysics Data System (ADS)

    Kraus, P. M.; Denning, S.

    2014-12-01

    An approach to representing soil moisture heterogeneity in land-surface models using bins of soil moisture, advancing on the method developed by Sellers et al., 2003 is presented. Structuring land-surface models in this fashion presents a desirable structure for coupling to atmospheric models utilizing the "multi-scale modeling framework", called "super-parameterization" in the Community Earth System Model, CESM. The multi-scale modeling framework substitutes conventional cloud parameterizations with a 2-D cloud-resolving model. By considering soil moisture heterogeneity, the land-surface model is able to utilize the distribution of precipitation simulated by the cloud-resolving model in the super-parameterization, rather than it's summed total.Additionally, treatments of gravitational drainage and runoff in the binned model are proposed and assessed. This is, in general, a conceptual addition to the binned approach of Sellers et al.; but it is also particularly motivated by the fine grid resolution of the cloud-resolving model used in super-parameterization, typically 2km.Preliminary results suggest that the binned-approach improves model representation of dry-down following rain events and may help mitigate some of the excessive latent heat fluxes simulated by the standard land model in the CESM.

  13. 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.

  14. Analysis of Divisible Load Scheduling with Result Collection on Heterogeneous Systems

    NASA Astrophysics Data System (ADS)

    Ghatpande, Abhay; Nakazato, Hidenori; Beaumont, Olivier; Watanabe, Hiroshi

    Divisible Load Theory (DLT) is an established framework to study Divisible Load Scheduling (DLS). Traditional DLT ignores the result collection phase, and specifies no solution to the general case where both the network speed and computing capacity of the nodes are heterogeneous. In this paper, the DLS with Result Collection on HETerogeneous Systems (DLSRCHETS) problem is formulated as a linear program and analyzed. The papers to date that have dealt with result collection, proposed simplistic LIFO (Last In, First Out) and FIFO (First In, First Out) type of schedules as solutions. The main contributions of this paper are: (a) A proof of the Allocation Precedence Condition, which is inconsequential in LIFO or FIFO, but is important in a general schedule. (b) A proof of the Idle Time Theorem, which states that irrespective of whether load is allocated to all available processors, in the optimal solution to the DLSRCHETS problem, at the most one processor that is allocated load has idle time, and that the idle time exists only when the result collection begins immediately after the completion of load distribution.

  15. Heterogeneous photo-catalysis system for the degradation of azo dye Reactive Black 5 (RB5).

    PubMed

    Huang, Yao-Hui; Wei, Hau-Cheng; Chen, Hung-Ta

    2012-01-01

    This study investigated a heterogeneous photo-catalysis system by introducing a novel brick supported iron oxide (denoted as B1) for the heterogeneous photoassisted degradation of Reactive Black 5 (RB5) at pH value from 3 to 7 in a three-phase (gas-liquid-solid) fluidized bed reactor (3P-FBR). Scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), X-ray powder diffraction (XRD) and N(2) adsorption/desorption were used to characterize the B1 catalyst. The in situ formation of hydrogen peroxide and the depletion of oxalic acid by photochemical cycle of Fe(III)-oxalate complex under UVA light (λ = 365 nm) were studied. The effects of the solution pH and the concentration of oxalic acid on the degradation of RB5 are elucidated. About 90% decolourization was measured and 80% of the total organic carbon (TOC) was eliminated at pH 5.0 after 120 min for 20 mg/L RB5 in presence of 10 g/L B1 catalyst, 30 mg/L oxalic acid under 15 W UVA light. A mechanism for the photocatalytic degradation of RB5 over B1 catalyst is proposed.

  16. Capillary pressure heterogeneity and hysteresis for the supercritical CO2/water system in a sandstone

    NASA Astrophysics Data System (ADS)

    Pini, Ronny; Benson, Sally M.

    2017-10-01

    We report results from an experimental investigation on the hysteretic behaviour of the capillary pressure curve for the supercritical CO2-water system in a Berea Sandstone core. Previous observations have highlighted the importance of subcore-scale capillary heterogeneity in developing local saturations during drainage; we show in this study that the same is true for the imbibition process. Spatially distributed drainage and imbibition scanning curves were obtained for mm-scale subsets of the rock sample non-invasively using X-ray CT imagery. Core- and subcore-scale measurements are well described using the Brooks-Corey formalism, which uses a linear trapping model to compute mobile saturations during imbibition. Capillary scaling yields two separate universal drainage and imbibition curves that are representative of the full subcore-scale data set. This enables accurate parameterisation of rock properties at the subcore-scale in terms of capillary scaling factors and permeability, which in turn serve as effective indicators of heterogeneity at the same scale even when hysteresis is a factor. As such, the proposed core-analysis workflow is quite general and provides the required information to populate numerical models that can be used to extend core-flooding experiments to conditions prevalent in the subsurface, which would be otherwise not attainable in the laboratory.

  17. Functional macrophage heterogeneity in a mouse model of autoimmune central nervous system pathology.

    PubMed

    London, Anat; Benhar, Inbal; Mattapallil, Mary J; Mack, Matthias; Caspi, Rachel R; Schwartz, Michal

    2013-04-01

    Functional macrophage heterogeneity is well appreciated outside the CNS in wound healing and cancer, and was recently also demonstrated in several CNS compartments after "sterile" insults. Yet, such heterogeneity was largely overlooked in the context of inflammatory autoimmune pathology, in which macrophages were mainly associated with disease induction and propagation. In this article, we show the diversity of monocyte-derived macrophages along the course of experimental autoimmune uveitis, an inflammatory condition affecting the ocular system, serving as a model for CNS autoimmune pathology. Disease induction resulted in the appearance of a distinct myeloid population in the retina, and in the infiltration of monocyte-derived macrophages that were absent from control eyes. During the disease course, the frequency of CX3CR1(high) infiltrating macrophages that express markers associated with inflammation-resolving activity was increased, along with a decrease in the frequency of inflammation-associated Ly6C(+) macrophages. Inhibition of monocyte infiltration at the induction phase of experimental autoimmune uveitis prevented disease onset, whereas monocyte depletion at the resolution phase resulted in a decrease in Foxp3(+) regulatory T cells and in exacerbated disease. Thus, monocyte-derived macrophages display distinct phenotypes throughout the disease course, even in an immune-induced pathology, reflecting their differential roles in disease induction and resolution.

  18. A method of determining where to target surveillance efforts in heterogeneous epidemiological systems

    PubMed Central

    van den Bosch, Frank; Gottwald, Timothy R.; Alonso Chavez, Vasthi

    2017-01-01

    The spread of pathogens into new environments poses a considerable threat to human, animal, and plant health, and by extension, human and animal wellbeing, ecosystem function, and agricultural productivity, worldwide. Early detection through effective surveillance is a key strategy to reduce the risk of their establishment. Whilst it is well established that statistical and economic considerations are of vital importance when planning surveillance efforts, it is also important to consider epidemiological characteristics of the pathogen in question—including heterogeneities within the epidemiological system itself. One of the most pronounced realisations of this heterogeneity is seen in the case of vector-borne pathogens, which spread between ‘hosts’ and ‘vectors’—with each group possessing distinct epidemiological characteristics. As a result, an important question when planning surveillance for emerging vector-borne pathogens is where to place sampling resources in order to detect the pathogen as early as possible. We answer this question by developing a statistical function which describes the probability distributions of the prevalences of infection at first detection in both hosts and vectors. We also show how this method can be adapted in order to maximise the probability of early detection of an emerging pathogen within imposed sample size and/or cost constraints, and demonstrate its application using two simple models of vector-borne citrus pathogens. Under the assumption of a linear cost function, we find that sampling costs are generally minimised when either hosts or vectors, but not both, are sampled. PMID:28846676

  19. 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.

  20. 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

  1. 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.

  2. Heterogeneous preferences, decision-making capacity, and phase transitions in a complex adaptive system.

    PubMed

    Wang, Wei; Chen, Yu; Huang, Jiping

    2009-05-26

    There has been a belief that with the directing power of the market, the efficient state of a resource-allocating system can eventually be reached even in a case where the resource is distributed in a biased way. To mimic the realistic huge system for the resource allocation, we designed and conducted a series of economic experiments. From the experiments we found that efficient allocation can be realized despite a lack of communications among the participants or any instructions to them. To explain the underlying mechanism, an extended minority game model called the market-directed resource allocation game (MDRAG) is constructed by introducing heterogeneous preferences into the strategy-building procedures. MDRAG can produce results in good agreement with the experiments. We investigated the influence of agents' decision-making capacity on the system behavior and the phase structure of the MDRAG model as well. A number of phase transitions are identified in the system. In the critical region, we found that the overall system will behave in an efficient, stable, and unpredictable mode in which the market's invisible hand can fully play its role.

  3. 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.

  4. Simulation of charged systems in heterogeneous dielectric media via a true energy functional.

    PubMed

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

    2012-11-30

    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.

  5. 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.

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

    PubMed Central

    Codeluppi, Simone; van Bruggen, David; Mendanha Falcão, Ana; Xiao, Lin; Li, Huiliang; Häring, Martin; Hochgerner, Hannah; Romanov, Roman A.; Gyllborg, Daniel; Muñoz Manchado, Ana; 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

    2016-01-01

    Oligodendrocytes have been considered as a functionally homogenous population in the central nervous system (CNS). We performed single-cell RNA-Seq on 5072 cells of the oligodendrocyte lineage from ten regions of the mouse juvenile/adult CNS. Twelve populations were identified, representing a continuum from Pdgfra+ oligodendrocyte precursors (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 found to be resident in the adult CNS and 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

  7. 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.

  8. Optimal Output Regulation for Heterogeneous Multiagent Systems via Adaptive Dynamic Programming.

    PubMed

    Zhang, Huaguang; Liang, Hongjing; Wang, Zhanshan; Feng, Tao

    2017-01-01

    In this paper, the optimal output regulation problem for partially model-free heterogeneous linear multiagent systems with disturbance generated by an exosystem is addressed by using adaptive dynamic programming and double compensator method. The topology graph for the information exchange of the agents has a spanning tree. The dynamic of individual agent is assumed to be nonidentical and of different dimensions. One distributed compensator is designed to deal with the nonidentical agents, and the other compensator is used to handle the optimal performance index. By constructing the double compensator, the distributed feedback control laws are designed to make the output of each agent synchronize with the reference output and minimize the energy of the output error simultaneously. To overcome the lack of the dynamics knowledge of each agent, a novel online policy iteration algorithm is developed to obtain the optimal feedback gain matrix. Finally, two examples are presented to illustrate the effectiveness of our results.

  9. A grid-enabled MPI : message passing in heterogeneous distributed computing systems.

    SciTech Connect

    Foster, I.; Karonis, N. T.

    2000-11-30

    Application development for high-performance distributed computing systems, or computational grids as they are sometimes called, requires grid-enabled tools that hide mundate aspects of the heterogeneous grid environment without compromising performance. As part of an investigation of these issues, they have developed MPICH-G, a grid-enabled implementation of the Message Passing Interface (MPI) that allows a user to run MPI programs across multiple computers at different sites using the same commands that would be used on a parallel computer. This library extends the Argonne MPICH implementation of MPI to use services provided by the globus grid toolkit. In this paper, they describe the MPICH-G implementation and present preliminary performance results.

  10. 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

  11. 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

  12. 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.

  13. 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

  14. 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.

  15. 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.

  16. Influence of heterogeneities within the lithosphere on the deformation pattern of continental rift systems.

    NASA Astrophysics Data System (ADS)

    Philippon, Melody; Thieulot, Cedric; van Wijk, Jolante; Sokoutis, Dimitrios; Willingshofer, Ernst; Cloetingh, Sierd

    2013-04-01

    Understanding how heterogeneities within the lithosphere influence the deformation pattern in continental rifts still remains a challenge and is of real importance to constrain continental break-up. We have selected the Main Ethiopian Rift in East Africa and the Rio Grande Rift in the south-western U.S. These two rifts are perfect natural laboratories to investigate the effect of inherited as they share similar structural characteristics but develop above different kinds of lithosphere-scale heterogeneities. From a structural point of view both rifts show similar length (1000km), width (50 to 70 km) and asymmetry. The Main Ethiopian rift is the NE-SW trending plate boundary between the Nubian and Somalian plates that has been developing for the past 11 Ma above a palaeo-Proterozoic lithospheric-scale weak zone re-heated by the Afar hotspot, whereas the Rio Grande Rift is the eastern "boundary" of the Basin & Range system which has been developing for the past 30 Ma in the frame of a westward-retreating Farallon subduction zone. However, the Rio Grande Rift shows evidence of low angle normal faulting whereas the Main Ethiopian Rift shows steeply dipping (with a mean close to 70°) normal faults. The Main Ethiopian Rift shows larger volume of erupted lavas than the Rio Grande Rift. Combined with a structural analyses of both rifts, we present here a series of 2D cross sections numerical models that allow better understanding of the influence of initial heterogeneities such as 1) the rheological state of the crust; 2) the presence of a crustal-scale to lithospheric-scale discrete weak or strong zone, 3) the effects of the presence of magma. We illustrate that rheological boundaries are not reactivated if the rheological contrast it too high, which is the case of the Rio Grande Rift that developed to the east of the North American Craton within thinned lithosphere. We also illustrate that the width of the weak zone do no have any influence on the exhumation of the

  17. Uranium transport experiments at the intermediate scale: Do more heterogeneous systems create more complex behaviors?

    NASA Astrophysics Data System (ADS)

    Miller, A. W.; Rodriguez, D.; Honeyman, B.

    2010-12-01

    With respect to complexity, two things occur as experimental scale increases. The first is that as total system size increases, the heterogeneities at smaller scales are explicitly included while simultaneously allowing for a general increase in total complexity. The second is that model constraining measurements become more difficult to make. Bench scale systems limit total complexity; field scale systems are limited in the amount of characterization that can be completed. Intermediate scale systems can bridge this gap, allowing for increased complexity relative to the bench scale and better characterization ability relative to the field scale. We have completed three intermediate scale experiments with a uranium contaminated sediment from a former uranium mill site near Naturita in southwestern Colorado, USA. Three tanks were packed with various particle size distributions of this sediment. The first two tanks were 2-D in nature and had dimensions of 2.44m x 1.22m x 7.62cm (tank #1, LxHxW), and 2.44m x 0.61m x 7.62cm (tank #2, LxHxW). Tank #3 was 3-D in nature with dimensions of 2.44m x 0.61m x 0.61m (LxHxW). Tank #1 was packed in a homogenous manner with only the <2mm size fraction of sediment. For tank #2 the <2mm fraction was split into <0.250mm and >0.250mm fractions, and these two fractions allowed for a physically heterogeneous packing. Using all three of the previously mentioned size fractions as well as a 0.125-0.250mm and a 4-12mm fraction, tank #3 was also packed in a heterogeneous fashion. The masses of sediment used in the three tanks are: tank #1 ~280kg, tank #2 - 163kg, and tank #3 - 1160kg. Flow through all three systems was comparable, and controlled by constant head boundaries. Three different artificial ground waters (AGW) were used with ionic compositions similar to that found at the field site. The major distinctions are that AGW #1 was in equilibrium with atmospheric CO2 and had no Si; AGW#2 was in equilibrium with 2%CO2 and had no Si; AGW#3

  18. 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.

  19. 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

  20. A Heterogeneous Sensing System-Based Method for Unmanned Aerial Vehicle Indoor Positioning.

    PubMed

    Wang, Can; Li, Kang; Liang, Guoyuan; Chen, Haoyao; Huang, Sheng; Wu, Xinyu

    2017-08-10

    The indoor environment has brought new challenges for micro Unmanned Aerial Vehicles (UAVs) in terms of their being able to execute tasks with high positioning accuracy. Conventional positioning methods based on GPS are unreliable, although certain circumstances of limited space make it possible to apply new technologies. In this paper, we propose a novel indoor self-positioning system of UAV based on a heterogeneous sensing system, which integrates data from a structured light scanner, ultra-wideband (UWB), and an inertial navigation system (INS). We made the structured light scanner, which is composed of a low-cost structured light and camera, ourselves to improve the positioning accuracy at a specified area. We applied adaptive Kalman filtering to fuse the data from the INS and UWB while the vehicle was moving, as well as Gauss filtering to fuse the data from the UWB and the structured light scanner in a hovering state. The results of our simulations and experiments demonstrate that the proposed strategy significantly improves positioning accuracy in motion and also in the hovering state, as compared to using a single sensor.

  1. 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

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

    DOE PAGES

    Roy, Dibyendu; Yang, Luyi; Crooker, Scott 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

  3. 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.

  4. 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. Copyright © 2012 IPEM. Published by Elsevier Ltd. All rights reserved.

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

    PubMed Central

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

    2015-01-01

    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. PMID:25924953

  6. 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.

  7. 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.

  8. An overview of the heterogeneous telescope network system: Concept, scalability and operation

    NASA Astrophysics Data System (ADS)

    White, R. R.; Allan, A.

    2008-03-01

    In the coming decade there will be an avalanche of data streams devoted to astronomical exploration opening new windows of scientific discovery. The shear volume of data and the diversity of event types (Kantor 2006; Kaiser 2004; Vestrand & Theiler & Wozniak 2004) will necessitate; the move to a common language for the communication of event data, and enabling telescope systems with the ability to not just simply respond, but to act independently in order to take full advantage of available resources in a timely manner. Developed over the past three years, the Virtual Observatory Event (VOEvent) provides the best format for carrying these diverse event messages (White et al. 2006a; Seaman & Warner 2006). However, in order for the telescopes to be able to act independently, a system of interoperable network nodes must be in place, that will allow the astronomical assets to not only issue event notifications, but to coordinate and request specific observations. The Heterogeneous Telescope Network (HTN) is a network architecture that can achieve the goals set forth and provide a scalable design to match both fully autonomous and manual telescope system needs (Allan et al. 2006a; White et al. 2006b; Hessman 2006b). In this paper we will show the design concept of this meta-network and nodes, their scalable architecture and complexity, and how this concept can meet the needs of institutions in the near future.

  9. A Heterogeneous Sensing System-Based Method for Unmanned Aerial Vehicle Indoor Positioning †

    PubMed Central

    Li, Kang; Liang, Guoyuan; Huang, Sheng; Wu, Xinyu

    2017-01-01

    The indoor environment has brought new challenges for micro Unmanned Aerial Vehicles (UAVs) in terms of their being able to execute tasks with high positioning accuracy. Conventional positioning methods based on GPS are unreliable, although certain circumstances of limited space make it possible to apply new technologies. In this paper, we propose a novel indoor self-positioning system of UAV based on a heterogeneous sensing system, which integrates data from a structured light scanner, ultra-wideband (UWB), and an inertial navigation system (INS). We made the structured light scanner, which is composed of a low-cost structured light and camera, ourselves to improve the positioning accuracy at a specified area. We applied adaptive Kalman filtering to fuse the data from the INS and UWB while the vehicle was moving, as well as Gauss filtering to fuse the data from the UWB and the structured light scanner in a hovering state. The results of our simulations and experiments demonstrate that the proposed strategy significantly improves positioning accuracy in motion and also in the hovering state, as compared to using a single sensor. PMID:28796184

  10. 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

  11. 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

  12. 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

  13. Finite-size scaling in the system of coupled oscillators with heterogeneity in coupling strength

    NASA Astrophysics Data System (ADS)

    Hong, Hyunsuk

    2017-07-01

    We consider a mean-field model of coupled phase oscillators with random heterogeneity in the coupling strength. The system that we investigate here is a minimal model that contains randomness in diverse values of the coupling strength, and it is found to return to the original Kuramoto model [Y. Kuramoto, Prog. Theor. Phys. Suppl. 79, 223 (1984), 10.1143/PTPS.79.223] when the coupling heterogeneity disappears. According to one recent paper [H. Hong, H. Chaté, L.-H. Tang, and H. Park, Phys. Rev. E 92, 022122 (2015), 10.1103/PhysRevE.92.022122], when the natural frequency of the oscillator in the system is "deterministically" chosen, with no randomness in it, the system is found to exhibit the finite-size scaling exponent ν ¯=5 /4 . Also, the critical exponent for the dynamic fluctuation of the order parameter is found to be given by γ =1 /4 , which is different from the critical exponents for the Kuramoto model with the natural frequencies randomly chosen. Originally, the unusual finite-size scaling behavior of the Kuramoto model was reported by Hong et al. [H. Hong, H. Chaté, H. Park, and L.-H. Tang, Phys. Rev. Lett. 99, 184101 (2007), 10.1103/PhysRevLett.99.184101], where the scaling behavior is found to be characterized by the unusual exponent ν ¯=5 /2 . On the other hand, if the randomness in the natural frequency is removed, it is found that the finite-size scaling behavior is characterized by a different exponent, ν ¯=5 /4 [H. Hong, H. Chaté, L.-H. Tang, and H. Park, Phys. Rev. E 92, 022122 (2015), 10.1103/PhysRevE.92.022122]. Those findings brought about our curiosity and led us to explore the effects of the randomness on the finite-size scaling behavior. In this paper, we pay particular attention to investigating the finite-size scaling and dynamic fluctuation when the randomness in the coupling strength is considered.

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

    DOE PAGES

    Klimentov, A.; Buncic, P.; De, K.; ...

    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

  15. 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.

  16. Photo-Induced Absorption Band in One-Dimensional Halogen-Bridged Mixed-Valence Platinum Complex: [Pt(en)2][PtI2(en)2](SO4)2\\cdot6H2O and its Au-Doped Complex: [AuxPt1-xI(en)2]SO4\\cdot3H2O

    NASA Astrophysics Data System (ADS)

    Matsushita, Nobuyuki; Kojima, Norimichi; Ban, Toshiro; Tsujikawa, Ikuji

    1987-11-01

    The intervalence charge-transfer absorption spectra in the mixed-valence complexes [Pt(en)2][PtI2(en)2](SO4)2\\cdot6H2O and [AuxPt1-xI(en)2]SO4\\cdot3H2O (x{=}0.03) have been investigated at 4.2 K. In these complexes, below the charge-transfer absorption edge, a weak absorption band (A-band) has been observed for the light polarized parallel to the chain axis. When these complexes were irradiated with the light in the region of the charge-transfer transition from PtII to PtIV, the absorption coefficient of the A-band increased remarkably, which implies that the A-band is a photo-induced absorption band. The photo-induced effect for the A-band in [AuxPt1-xI(en)2]SO4\\cdot3H2O (x{=}0.03) is more intense than that in [Pt(en)2][PtI2(en)2](SO4)2\\cdot6H2O. The A-band suggests the existence of new excitations such as a soliton-like excitation in the electronic state of the platinum chains.

  17. 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

  18. 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.

  19. 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.

  20. Reaction Event Counting Statistics of Biopolymer Reaction Systems with Dynamic Heterogeneity.

    PubMed

    Lim, Yu Rim; Park, Seong Jun; Park, Bo Jung; Cao, Jianshu; Silbey, Robert J; Sung, Jaeyoung

    2012-04-10

    We investigate the reaction event counting statistics (RECS) of an elementary biopolymer reaction in which the rate coefficient is dependent on states of the biopolymer and the surrounding environment and discover a universal kinetic phase transition in the RECS of the reaction system with dynamic heterogeneity. From an exact analysis for a general model of elementary biopolymer reactions, we find that the variance in the number of reaction events is dependent on the square of the mean number of the reaction events when the size of measurement time is small on the relaxation time scale of rate coefficient fluctuations, which does not conform to renewal statistics. On the other hand, when the size of the measurement time interval is much greater than the relaxation time of rate coefficient fluctuations, the variance becomes linearly proportional to the mean reaction number in accordance with renewal statistics. Gillespie's stochastic simulation method is generalized for the reaction system with a rate coefficient fluctuation. The simulation results confirm the correctness of the analytic results for the time dependent mean and variance of the reaction event number distribution. On the basis of the obtained results, we propose a method of quantitative analysis for the reaction event counting statistics of reaction systems with rate coefficient fluctuations, which enables one to extract information about the magnitude and the relaxation times of the fluctuating reaction rate coefficient, without a bias that can be introduced by assuming a particular kinetic model of conformational dynamics and the conformation dependent reactivity. An exact relationship is established between a higher moment of the reaction event number distribution and the multitime correlation of the reaction rate for the reaction system with a nonequilibrium initial state distribution as well as for the system with the equilibrium initial state distribution.

  1. Mycobactericidal activity of hydrogen peroxide activated by a novel heterogeneous Fentons-like catalyst system.

    PubMed

    Price, S L; Huddersman, K D; Shen, J; Walsh, S E

    2013-02-01

    To investigate the potential activation of hydrogen peroxide by a novel catalyst, reducing the concentration of hydrogen peroxide required and the time taken for mycobactericidal activity. The mycobactericidal properties of an iron-based novel heterogeneous-modified polyacrylonitrile (PAN) catalyst in combination with hydrogen peroxide were examined against Mycobacterium chelonae using a modified version of the European suspension test. Mycobactericidal activity was significantly increased when the modified PAN catalyst was combined with hydrogen peroxide. The 0·5% w/v hydrogen peroxide and 2-g catalyst system resulted in average Log reductions of >5·80 for Myco. chelonae at 30-min exposure at room temperature. This was a significant increase in activity (P < 0·01) compared to 0·5% w/v hydrogen peroxide alone. This study has expanded on previous work and knowledge of the modified PAN catalyst and hydrogen peroxide system, by providing evidence for mycobactericidal activity when the novel PAN catalyst is combined with hydrogen peroxide. © 2012 The Society for Applied Microbiology.

  2. 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.

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

    PubMed

    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.

  4. 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.

  5. 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.

  6. Output Containment Control of Linear Heterogeneous Multi-Agent Systems Using Internal Model Principle.

    PubMed

    Zuo, Shan; Song, Yongduan; Lewis, Frank L; Davoudi, Ali

    2017-01-04

    This paper studies the output containment control of linear heterogeneous multi-agent systems, where the system dynamics and even the state dimensions can generally be different. Since the states can have different dimensions, standard results from state containment control do not apply. Therefore, the control objective is to guarantee the convergence of the output of each follower to the dynamic convex hull spanned by the outputs of leaders. This can be achieved by making certain output containment errors go to zero asymptotically. Based on this formulation, two different control protocols, namely, full-state feedback and static output-feedback, are designed based on internal model principles. Sufficient local conditions for the existence of the proposed control protocols are developed in terms of stabilizing the local followers' dynamics and satisfying a certain H∞ criterion. Unified design procedures to solve the proposed two control protocols are presented by formulation and solution of certain local state-feedback and static output-feedback problems, respectively. Numerical simulations are given to validate the proposed control protocols.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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

  12. 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

  13. CMSA: a heterogeneous CPU/GPU computing system for multiple similar RNA/DNA sequence alignment.

    PubMed

    Chen, Xi; Wang, Chen; Tang, Shanjiang; Yu, Ce; Zou, Quan

    2017-06-24

    The multiple sequence alignment (MSA) is a classic and powerful technique for sequence analysis in bioinformatics. With the rapid growth of biological datasets, MSA parallelization becomes necessary to keep its running time in an acceptable level. Although there are a lot of work on MSA problems, their approaches are either insufficient or contain some implicit assumptions that limit the generality of usage. First, the information of users' sequences, including the sizes of datasets and the lengths of sequences, can be of arbitrary values and are generally unknown before submitted, which are unfortunately ignored by previous work. Second, the center star strategy is suited for aligning similar sequences. But its first stage, center sequence selection, is highly time-consuming and requires further optimization. Moreover, given the heterogeneous CPU/GPU platform, prior studies consider the MSA parallelization on GPU devices only, making the CPUs idle during the computation. Co-run computation, however, can maximize the utilization of the computing resources by enabling the workload computation on both CPU and GPU simultaneously. This paper presents CMSA, a robust and efficient MSA system for large-scale datasets on the heterogeneous CPU/GPU platform. It performs and optimizes multiple sequence alignment automatically for users' submitted sequences without any assumptions. CMSA adopts the co-run computation model so that both CPU and GPU devices are fully utilized. Moreover, CMSA proposes an improved center star strategy that reduces the time complexity of its center sequence selection process from O(mn (2)) to O(mn). The experimental results show that CMSA achieves an up to 11× speedup and outperforms the state-of-the-art software. CMSA focuses on the multiple similar RNA/DNA sequence alignment and proposes a novel bitmap based algorithm to improve the center star strategy. We can conclude that harvesting the high performance of modern GPU is a promising approach to

  14. 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

  15. 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.

  16. Energy resolution and dynamical heterogeneity effects on elastic incoherent neutron scattering from molecular systems.

    PubMed

    Becker, Torsten; Smith, Jeremy C

    2003-02-01

    Incoherent neutron scattering is widely used to probe picosecond-nanosecond time scale dynamics of molecular systems. In systems of spatially confined atoms the relatively high intensity of elastic incoherent neutron scattering is often used to obtain a first estimate of the dynamics present. For many complex systems, however, experimental elastic scattering is difficult to interpret unambiguously using analytical dynamical models that go beyond the determination of an average mean-square displacement. To circumvent this problem a description of the scattering is derived here that encompasses a variety of analytical models in a common framework. The framework describes the time-converged part of the dynamic structure factor [the elastic incoherent scattering function (EISF)] and lends itself to practical use by explicitly incorporating effects due to the finite energy resolution of the instrument used. The dependence of the elastic scattering on wave vector is examined, and it is shown how heterogeneity in the distribution of mean-square displacements can be related to deviations of the scattering from Gaussian behavior. In this case, a correction to fourth order in the scattering vector can be used to extract the variance of the distribution of mean-square displacements. The formalism is used in a discussion of measurements on dynamics accompanying the glass transition in molecular systems. By fitting to experimental data obtained on a protein solution the present methodology is used to show how the existence of a temperature-dependent relaxation frequency can lead to a transition in the measured mean-square displacement in the absence of an EISF change.

  17. 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.

  18. Systems and precision medicine approaches to diabetes heterogeneity: a Big Data perspective.

    PubMed

    Capobianco, Enrico

    2017-12-01

    Big Data, and in particular Electronic Health Records, provide the medical community with a great opportunity to analyze multiple pathological conditions at an unprecedented depth for many complex diseases, including diabetes. How can we infer on diabetes from large heterogeneous datasets? A possible solution is provided by invoking next-generation computational methods and data analytics tools within systems medicine approaches. By deciphering the multi-faceted complexity of biological systems, the potential of emerging diagnostic tools and therapeutic functions can be ultimately revealed. In diabetes, a multidimensional approach to data analysis is needed to better understand the disease conditions, trajectories and the associated comorbidities. Elucidation of multidimensionality comes from the analysis of factors such as disease phenotypes, marker types, and biological motifs while seeking to make use of multiple levels of information including genetics, omics, clinical data, and environmental and lifestyle factors. Examining the synergy between multiple dimensions represents a challenge. In such regard, the role of Big Data fuels the rise of Precision Medicine by allowing an increasing number of descriptions to be captured from individuals. Thus, data curations and analyses should be designed to deliver highly accurate predicted risk profiles and treatment recommendations. It is important to establish linkages between systems and precision medicine in order to translate their principles into clinical practice. Equivalently, to realize their full potential, the involved multiple dimensions must be able to process information ensuring inter-exchange, reducing ambiguities and redundancies, and ultimately improving health care solutions by introducing clinical decision support systems focused on reclassified phenotypes (or digital biomarkers) and community-driven patient stratifications.

  19. 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

  20. [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.

  1. 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.

  2. 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.

  3. 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

  4. 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.

  5. Photodegradation of orange I in the heterogeneous iron oxide-oxalate complex system under UVA irradiation.

    PubMed

    Lei, Jing; Liu, Chengshuai; Li, Fangbai; Li, Xiaomin; Zhou, Shungui; Liu, Tongxu; Gu, Minghua; Wu, Qitang

    2006-09-21

    To understand the photodegradation of azo dyes in natural aquatic environment, a novel photo-Fenton-like system, the heterogeneous iron oxide-oxalate complex system was set up with the existence of iron oxides and oxalate. Five iron oxides, including gamma-FeOOH, IO-250, IO-320, IO-420 and IO-520, were prepared and their adsorption capacity was investigated in the dark. The results showed that the saturated adsorption amount (gamma(max)) was ranked the order of IO-250 > IO-320 > gamma-FeOOH > IO-420 > IO-520 and the adsorption equilibrium constant (Ka) followed the order of IO-250 > IO-520 > gamma-FeOOH > IO-420 > IO-320. The effect of initial pH value, the initial concentrations of oxalate and orange I on the photodegradation of orange I were also investigated in different iron oxide-oxalate systems. The results showed that the photodegradation of orange I under UVA irradiation could be enhanced greatly in the presence of oxalate. And the optimal oxalate concentrations (C(ox)0) for gamma-FeOOH, IO-250, IO-320, IO-420 and IO-520 were 1.8, 1.6, 3.5, 3.0 and 0.8 mM, respectively. The photodegradation of orange I in the presence of optimal C(ox)0 was ranked as the order of gamma-FeOOH > IO-250 > IO-320 > IO-420 > IO-520. The optimal range of initial pH was at about 3-4. The first-order kinetic constant for the degradation of orange I decreased with the increase in the initial concentration of orange I. Furthermore, the variation of pH, the concentrations of Fe3+ and Fe2+ during the photoreaction were also strongly dependent on the C(ox)0 and iron oxides.

  6. Do existing classification systems capture mountain snowpack heterogeneity? Accounting for spatial variability in a changing environment

    NASA Astrophysics Data System (ADS)

    Tennant, C.; Godsey, S.; Harpold, A. A.; Link, T. E.; Rajagopal, S.; Larsen, L.

    2016-12-01

    Spatial patterns of snow accumulation and melt control water and nutrient fluxes from mountain landscapes and determine the dynamics of resource availability for nearby human and ecological communities. Because seasonal snowpack is sensitive to changes in regional climate, there is a growing need for a snowpack classification system that (1) recognizes salient processes, (2) captures the variance of the system, (3) recognizes temporal and/or spatial change, and (4) has application to predicting snowmelt runoff regimes. Previous classification systems have focused on textural and stratigraphic snow characteristics or climatological observations to map broad geographic classes (e.g. maritime, continental, ephemeral, etc.). While these approaches have revealed general patterns, they may not capture the spatial heterogeneity of snowpack characteristics that are common across high relief terrain. Here, we use 1 km resolution gridded outputs from a physically based, spatially-distributed energy- and mass-balance snow model (SNODAS) to produce a snow classification system for the western U.S. and Great Plains. To meet the outlined criterion, we initially explored the ability of a large number of metrics (13) to characterize the amount, timing, and melt-rate of snowpack. Principal components analysis and pairwise correlations were used to identify a subset of metrics (6) that captured the variance of the system but also contributed unique information. K-means was used to delineate 12 process-based groups that reveal both climatic and orographic influences on snowpack accumulation, timing, and melt rate. The important effects of elevation-mediated processes in our classification system suggest a greater spatial diversity in snowpack patterns than suggested by previous characterizations (e.g. maritime-to-continental). Application of the system from the early 2000's to present reveals that interannual temporal and spatial variability have been greatest in the Columbia Plateau

  7. 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.

  8. 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.

  9. A Reconfigurable Readout Integrated Circuit for Heterogeneous Display-Based Multi-Sensor Systems.

    PubMed

    Park, Kyeonghwan; Kim, Seung Mok; Eom, Won-Jin; Kim, Jae Joon

    2017-04-03

    This paper presents a reconfigurable multi-sensor interface and its readout integrated circuit (ROIC) for display-based multi-sensor systems, which builds up multi-sensor functions by utilizing touch screen panels. In addition to inherent touch detection, physiological and environmental sensor interfaces are incorporated. The reconfigurable feature is effectively implemented by proposing two basis readout topologies of amplifier-based and oscillator-based circuits. For noise-immune design against various noises from inherent human-touch operations, an alternate-sampling error-correction scheme is proposed and integrated inside the ROIC, achieving a 12-bit resolution of successive approximation register (SAR) of analog-to-digital conversion without additional calibrations. A ROIC prototype that includes the whole proposed functions and data converters was fabricated in a 0.18 μm complementary metal oxide semiconductor (CMOS) process, and its feasibility was experimentally verified to support multiple heterogeneous sensing functions of touch, electrocardiogram, body impedance, and environmental sensors.

  10. Wear forms of heterogeneous electro-rheological fluids working in a hydraulic clutch system

    NASA Astrophysics Data System (ADS)

    Ziabska, E.; Duchowski, J.; Olszak, A.; Osowski, K.; Kesy, A.; Kesy, Z.; Choi, S. B.

    2017-09-01

    The paper presents experimental results concerning the wear of heterogeneous electro-rheological (ER) fluids operating as working fluids in a complex clutch system consisting of a hydrodynamic clutch and a cylinder viscous clutch. The change of electric field intensity in the clutches results in change of sheer stress values in working fluids what causes the change of transmitted torque. This work shows that the most important factors affecting the wear of the ER fluid are the electric field of high intensity, the accompanying electrical breakdown, and the high temperature of the silicone oil. In addition, the water from the humid air absorbed mainly by hygroscopic particles influences a significant impact on the wear of the working fluid. Various forms of wear particles of the fluid depending on the prevailing conditions such as working mode are observed from the microscopic aspects. It is observed that the particles are flattened, rolled out or smashed into smaller fragments, partially melted, wrinkled and glued or caked. In addition, it is identified that the partial destruction of silicone oil is occurred due to the damage of the hydrocarbon chains, as evidenced by the decrease in its viscosity and the presence of the particle matter newly containing silicon.

  11. A multiscale dataset for understanding complex eco-hydrological processes in a heterogeneous oasis system

    NASA Astrophysics Data System (ADS)

    Li, Xin; Liu, Shaomin; Xiao, Qin; Ma, Mingguo; Jin, Rui; Che, Tao; Wang, Weizhen; Hu, Xiaoli; Xu, Ziwei; Wen, Jianguang; Wang, Liangxu

    2017-06-01

    We introduce a multiscale dataset obtained from Heihe Watershed Allied Telemetry Experimental Research (HiWATER) in an oasis-desert area in 2012. Upscaling of eco-hydrological processes on a heterogeneous surface is a grand challenge. Progress in this field is hindered by the poor availability of multiscale observations. HiWATER is an experiment designed to address this challenge through instrumentation on hierarchically nested scales to obtain multiscale and multidisciplinary data. The HiWATER observation system consists of a flux observation matrix of eddy covariance towers, large aperture scintillometers, and automatic meteorological stations; an eco-hydrological sensor network of soil moisture and leaf area index; hyper-resolution airborne remote sensing using LiDAR, imaging spectrometer, multi-angle thermal imager, and L-band microwave radiometer; and synchronical ground measurements of vegetation dynamics, and photosynthesis processes. All observational data were carefully quality controlled throughout sensor calibration, data collection, data processing, and datasets generation. The data are freely available at figshare and the Cold and Arid Regions Science Data Centre. The data should be useful for elucidating multiscale eco-hydrological processes and developing upscaling methods.

  12. Virulence evolution of a generalist plant virus in a heterogeneous host system

    PubMed Central

    Betancourt, Mónica; Escriu, Fernando; Fraile, Aurora; García-Arenal, Fernando

    2013-01-01

    Modelling virulence evolution of multihost parasites in heterogeneous host systems requires knowledge of the parasite biology over its various hosts. We modelled the evolution of virulence of a generalist plant virus, Cucumber mosaic virus (CMV) over two hosts, in which CMV genotypes differ for within-host multiplication and virulence. According to knowledge on CMV biology over different hosts, the model allows for inoculum flows between hosts and for host co-infection by competing virus genotypes, competition affecting transmission rates to new hosts. Parameters of within-host multiplication, within-host competition, virulence and transmission were determined experimentally for different CMV genotypes in each host. Emergence of highly virulent genotypes was predicted to occur as mixed infections, favoured by high vector densities. For most simulated conditions, evolution to high virulence in the more competent Host 1 was little dependent on inoculum flow from Host 2, while in Host 2, it depended on transmission from Host 1. Virulence evolution bifurcated in each host at low, but not at high, vector densities. There was no evidence of between-host trade-offs in CMV life-history traits, at odds with most theoretical assumptions. Predictions agreed with field observations and are relevant for designing control strategies for multihost plant viruses. PMID:24062798

  13. Performance analysis of general purpose and digital signal processor kernels for heterogeneous systems-on-chip

    NASA Astrophysics Data System (ADS)

    von Sydow, T.; Blume, H.; Noll, T. G.

    2003-05-01

    Various reasons like technology progress, flexibility demands, shortened product cycle time and shortened time to market have brought up the possibility and necessity to integrate different architecture blocks on one heterogeneous System-on-Chip (SoC). Architecture blocks like programmable processor cores (DSP- and GPP-kernels), embedded FPGAs as well as dedicated macros will be integral parts of such a SoC. Especially programmable architecture blocks and associated optimization techniques are discussed in this contribution. Design space exploration and thus the choice which architecture blocks should be integrated in a SoC is a challenging task. Crucial to this exploration is the evaluation of the application domain characteristics and the costs caused by individual architecture blocks integrated on a SoC. An ATE-cost function has been applied to examine the performance of the aforementioned programmable architecture blocks. Therefore, representative discrete devices have been analyzed. Furthermore, several architecture dependent optimization steps and their effects on the cost ratios are presented.

  14. A multiscale dataset for understanding complex eco-hydrological processes in a heterogeneous oasis system

    PubMed Central

    Li, Xin; Liu, Shaomin; Xiao, Qin; Ma, Mingguo; Jin, Rui; Che, Tao; Wang, Weizhen; Hu, Xiaoli; Xu, Ziwei; Wen, Jianguang; Wang, Liangxu

    2017-01-01

    We introduce a multiscale dataset obtained from Heihe Watershed Allied Telemetry Experimental Research (HiWATER) in an oasis-desert area in 2012. Upscaling of eco-hydrological processes on a heterogeneous surface is a grand challenge. Progress in this field is hindered by the poor availability of multiscale observations. HiWATER is an experiment designed to address this challenge through instrumentation on hierarchically nested scales to obtain multiscale and multidisciplinary data. The HiWATER observation system consists of a flux observation matrix of eddy covariance towers, large aperture scintillometers, and automatic meteorological stations; an eco-hydrological sensor network of soil moisture and leaf area index; hyper-resolution airborne remote sensing using LiDAR, imaging spectrometer, multi-angle thermal imager, and L-band microwave radiometer; and synchronical ground measurements of vegetation dynamics, and photosynthesis processes. All observational data were carefully quality controlled throughout sensor calibration, data collection, data processing, and datasets generation. The data are freely available at figshare and the Cold and Arid Regions Science Data Centre. The data should be useful for elucidating multiscale eco-hydrological processes and developing upscaling methods. PMID:28654086

  15. Containment Control for Second-Order Multiagent Systems Communicating Over Heterogeneous Networks.

    PubMed

    Qin, Jiahu; Zheng, Wei Xing; Gao, Huijun; Ma, Qichao; Fu, Weiming

    2017-09-01

    The containment control is studied for the second-order multiagent systems over a heterogeneous network where the position and velocity interactions are different. We consider three cases that multiple leaders are stationary, moving at the same constant speed, and moving at the same time-varying speed, and develop different containment control algorithms for each case. In particular, for the former two cases, we first propose the containment algorithms based on the well-established ones for the homogeneous network, for which the position interaction topology is required to be undirected. Then, we extend the results to the general setting with the directed position and velocity interaction topologies by developing a novel algorithm. For the last case with time-varying velocities, we introduce two algorithms to address the containment control problem under, respectively, the directed and undirected interaction topologies. For most cases, sufficient conditions with regard to the interaction topologies are derived for guaranteeing the containment behavior and, thus, are easy to verify. Finally, six simulation examples are presented to illustrate the validity of the theoretical findings.

  16. A Reconfigurable Readout Integrated Circuit for Heterogeneous Display-Based Multi-Sensor Systems

    PubMed Central

    Park, Kyeonghwan; Kim, Seung Mok; Eom, Won-Jin; Kim, Jae Joon

    2017-01-01

    This paper presents a reconfigurable multi-sensor interface and its readout integrated circuit (ROIC) for display-based multi-sensor systems, which builds up multi-sensor functions by utilizing touch screen panels. In addition to inherent touch detection, physiological and environmental sensor interfaces are incorporated. The reconfigurable feature is effectively implemented by proposing two basis readout topologies of amplifier-based and oscillator-based circuits. For noise-immune design against various noises from inherent human-touch operations, an alternate-sampling error-correction scheme is proposed and integrated inside the ROIC, achieving a 12-bit resolution of successive approximation register (SAR) of analog-to-digital conversion without additional calibrations. A ROIC prototype that includes the whole proposed functions and data converters was fabricated in a 0.18 μm complementary metal oxide semiconductor (CMOS) process, and its feasibility was experimentally verified to support multiple heterogeneous sensing functions of touch, electrocardiogram, body impedance, and environmental sensors. PMID:28368355

  17. 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

  18. Genetic heterogeneity at the glycosyltransferase loci underlying the GLOB blood group system and collection.

    PubMed

    Hellberg, A; Ringressi, A; Yahalom, V; Säfwenberg, J; Reid, M E; Olsson, M L

    2004-05-01

    The aim of this study was to further explore the molecular genetic bases of the clinically important but rare blood group phenotypes p, P(1) (k) and P(2) (k) by analysis of the 4-alpha-galactosyltransferase (P(k)) and 3-beta-N-acetylgalactosaminyltransferase (P) genes responsible for synthesis of the related P(k) (Gb(3)) and P (Gb(4)) antigens respectively. Lack of these glycolipid moieties is associated with severe transfusion reactions and recurrent spontaneous abortions but also offers immunity against certain infectious agents. Blood samples from 20 p and 11 P(1) (k) or P(2) (k) individuals of different geographic and ethnic origin were investigated. DNA sequencing by capillary electrophoresis was performed following amplification of the coding regions in the P(k) or P genes. In the P(k) gene, nine novel and five previously described mutations were detected. One of the newly found mutations introduced an immediate stop, five shifted the reading frame introducing premature stop codons and three were missense mutations causing amino acid substitutions in conserved regions of the transferase. Four new and two previously described mutations in the P gene were found. Three of the novel alleles reported here carried nonsense mutations whilst the fourth allele had a missense mutation. The finding of 13 novel mutations in 14 alleles emphasizes further the genetic heterogeneity at the glycosyltransferase loci underlying the GLOB blood group system and collection.

  19. 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

  20. Investigating Strongly Correlated Behavior In The High T c Cuprate Bi2Sr2CaCu2O8+x And The Mixed Valence Compound CeSn3

    NASA Astrophysics Data System (ADS)

    Crocker, John Earl

    This dissertation is a culmination of my work in Nicholas Curro's Condensed Matter Experimental Laboratory from 2010 to 2015. In that time I have done magnetization and NMR based experiments. In addition I had the opportunity to characterize much of the equipment used in the Curro Lab. This dissertation is written for future graduate students to the Curro Lab. It is my hope you will find these pages useful and that they bring clarity to the day to day operations in the lab. There are five Chapters and five Appendices contained in this dissertation. Chapter 1 starts with an introduction to the theory of the experimental apparatus. Chapter 2 contains practical information on running experiments. Chapter 3 describes research on the High-Tc cuprate Bi2Sr 2CaCu2O8+x. Chapter 4 describes research on the mixed valent compound CeSn3. Chapter 5 provides concluding remarks to this dissertation. Appendix A describes a technique and experimentation for AC susceptibility with the present lab equipment. Appendix B discusses the construction and use of helium level meters. Appendix C discusses the helium liquefaction system employed in the lab and the operations and techniques associated with it. Appendix D presents a discussion of solving the normal modes problem for magnetic relaxation of high-spin nuclei. Lastly, Appendix E describes various characterizations on the equipment in the lab.

  1. 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

  2. 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

  3. 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

  4. Rapid evaluation for heterogeneities in monoclonal antibodies by liquid chromatography/mass spectrometry with a column-switching system.

    PubMed

    Kuribayashi, Ryosuke; Hashii, Noritaka; Harazono, Akira; Kawasaki, Nana

    2012-01-01

    The development of therapeutic antibodies has grown over the last several years. Most of the recombinant monoclonal antibodies (mAbs) produced by mammalian cells are glycoproteins. Glycosylation of the mAbs can be associated with effector functions, such as antibody-dependent cellular cytotoxicity and complement-dependent cytotoxicity, as well as immunogenicity and clearance. Thus, mAb glycan heterogeneity is a significant characteristic associated with the safety and efficacy of the products. Therefore, glycan heterogeneity should be evaluated during research and development (R&D) and during development of mAbs manufacturing processes to identify the process parameters that affect glycan heterogeneity and to enhance understanding of the manufacturing process. There is an increasing need for a rapid, easy, and automated evaluation method for glycan heterogeneity. Liquid chromatography/mass spectrometry (LC/MS) is a method that can be used to analyze glycoforms. LC/MS is marked by the ability to measure the oligosaccharide composition of each glycoform, whereas other general methods, such as capillary electrophoresis, sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and ion-exchange chromatography, cannot. However, a laborious off-line purification of mAbs is required to evaluate glycan heterogeneities. In this study, we demonstrate the use of a rapid, easy, and automated evaluation system for mAb glycoforms by LC/MS. This LC/MS system uses a column-switching system equipped with 2 columns, a protein A affinity column and a reversed-phase column (desalting column). We devised 2 column-switching systems: one that targeted intact mAbs (system 1) and one that targeted the light and heavy chains of the mAbs (system 2). Our results show that the proposed systems are applicable as a tool to evaluate the glycoforms in several situations, including the research, development, and production processes of mAbs. Additionally, we hope that our systems are useful as

  5. Capillary pressure and heterogeneity for the CO2/water system in sandstone rocks

    NASA Astrophysics Data System (ADS)

    Pini, R.; Krevor, S. C.; Benson, S. M.

    2011-12-01

    In the context of CO2 storage the mechanical equilibrium between the water and the CO2 phase in the porous structure of the hosting geological formation is governed by hydrostatic, gravity forces and capillary action. Although the magnitude of the capillary pressure in most reservoirs is usually not large, its effects are important: the character of the CO2/water capillary pressure affects relative permeability and the distribution of fluids in the subsurface. Capillary forces are responsible for residual trapping, a phenomenon that could contribute substantially to the overall balance of sequestered CO2 over the hundred-year time scale. In addition, simulation studies clearly show the importance of capillary heterogeneity at the sub-score scale on CO2 movement, but experimental techniques are needed for quantitative observation of these phenomena. Traditional techniques to measure capillary pressure curves on whole cores and with reservoir fluids are time consuming, and the current experimental data set consists mainly of results from mercury intrusion porosimetry (MICP) that have been converted to the CO2/water system. The extent to which these data are representative for reservoir conditions has to be questioned, as the wetting properties of the CO2/water system are unknown and interfacial tension estimates are still uncertain. A novel method is presented in this paper to measure capillary pressure curves both at the core and sub-core scale using CO2 and water at reservoir conditions. The technique exploits the so-called capillary end-effect, a common phenomenon observed in core-flooding experiments, which results from a tendency of the wetting phase to form a continuous phase across the outlet face of the sample. From a practical point of view, an experimental configuration is used that is very similar to the one used in traditional steady-state relative permeability experiments. Drainage capillary pressure curves of CO2 and water are measured for two

  6. A system for tumor heterogeneity evaluation and diagnosis based on tumor markers measured routinely in the laboratory.

    PubMed

    Hui, Liu; Rixv, Liu; Xiuying, Zhou

    2015-12-01

    To develop an efficient and reliable approach to estimate tumor heterogeneity and improve tumor diagnosis using multiple tumor markers measured routinely in the clinical laboratory. A total of 161 patients with different cancers were recruited as the cancer group, and 91 patients with non-oncological conditions were required as the non-oncological disease group. The control group comprised 90 randomly selected healthy subjects. AFP, CEA, CYFRA, CA125, CA153, CA199, CA724, and NSE levels were measured in all these subjects with a chemiluminescent microparticle immunoassay. The tumor marker with the maximum S/CO value (sample test value:cutoff value for discriminating individuals with and without tumors) was considered as a specific tumor marker (STM) for an individual. Tumor heterogeneity index (THI)=N/P (N: number of STMs; P: percentage of individuals with STMs in a certain tumor population) was used to quantify tumor heterogeneity: high THI indicated high tumor heterogeneity. The tumor marker index (TMI), TMI = STM×(number of positive tumor markers+1), was used for diagnosis. The THIs of lung, gastric, and liver cancers were 8.33, 9.63, and 5.2, respectively, while the ROC-areas under the curve for TMI were 0.862, 0.809, and 0.966. In this study, we developed a novel index for tumor heterogeneity based on the expression of various routinely evaluated serum tumor markers. Development of an evaluation system for tumor heterogeneity on the basis of this index could provide an effective diagnostic tool for some cancers. Copyright © 2015 The Canadian Society of Clinical Chemists. Published by Elsevier Inc. All rights reserved.

  7. A heterogeneous boron distribution in soil influences the poplar root system architecture development

    NASA Astrophysics Data System (ADS)

    Rees, R.; Robinson, B. H.; Hartmann, S.; Lehmann, E.; Schulin, R.

    2009-04-01

    Poplars are well suited for the phytomanagement of boron (B)-contaminated sites, due to their high transpiration rate and tolerance to elevated soil B concentrations. However, the uptake and the fate of B in poplar stands are not well understood. This information is crucial to improve the design of phytomanagement systems, where the primary role of poplars is to reduce B leaching by reducing the water flux through the contaminated material. Like other trace elements, B occurs heterogeneously in soils. Concentrations can differ up to an order of magnitude within centimetres. These gradients affect plant root growth and thus via preferential flow along the roots water and mass transport in soils to ground and surface waters. Generally there are three possible reactions of plant roots to patches with elevated trace element concentrations in soils: indifference, avoidance, or foraging. While avoidance or indifference might seem to be the most obvious strategies, foraging cannot be excluded a priori, because of the high demand of poplars for B compared to other tree species. We aimed to determine the rooting strategies of poplars in soils where B is either homo- or heterogeneously distributed. We planted 5 cm cuttings of Populus tremula var. Birmensdorf clones in aluminum (Al) containers with internal dimensions of 64 x 67 x 1.2 cm. The soil used was subsoil from northern Switzerland with a naturally low B and organic C concentration. We setup two treatments and a control with three replicates each. We spiked a bigger and a smaller portion of the soil with the same amount of B(OH)3-salt, in order to obtain soil concentrations of 7.5 mg B kg-1 and 20 mg B kg-1. We filled the containers with (a) un-spiked soil, (b) the 7.5 mg B kg-1 soil and (c) heterogeneously. The heterogeneous treatment consisted of one third 20 mg B kg-1 soil and two thirds control soil. We grew the poplars in a small greenhouse over 2 months and from then on in a climate chamber for another 3 months

  8. Allelic heterogeneity in NCF2 associated with systemic lupus erythematosus (SLE) susceptibility across four ethnic populations.

    PubMed

    Kim-Howard, Xana; Sun, Celi; Molineros, Julio E; Maiti, Amit K; Chandru, Hema; Adler, Adam; Wiley, Graham B; Kaufman, Kenneth M; Kottyan, Leah; Guthridge, Joel M; Rasmussen, Astrid; Kelly, Jennifer; Sánchez, Elena; Raj, Prithvi; Li, Quan-Zhen; Bang, So-Young; Lee, Hye-Soon; Kim, Tae-Hwan; Kang, Young Mo; Suh, Chang-Hee; Chung, Won Tae; Park, Yong-Beom; Choe, Jung-Yoon; Shim, Seung Cheol; Lee, Shin-Seok; Han, Bok-Ghee; Olsen, Nancy J; Karp, David R; Moser, Kathy; Pons-Estel, Bernardo A; Wakeland, Edward K; James, Judith A; Harley, John B; Bae, Sang-Cheol; Gaffney, Patrick M; Alarcón-Riquelme, Marta; Looger, Loren L; Nath, Swapan K

    2014-03-15

    Recent reports have associated NCF2, encoding a core component of the multi-protein NADPH oxidase (NADPHO), with systemic lupus erythematosus (SLE) susceptibility in individuals of European ancestry. To identify ethnicity-specific and -robust variants within NCF2, we assessed 145 SNPs in and around the NCF2 gene in 5325 cases and 21 866 controls of European-American (EA), African-American (AA), Hispanic (HS) and Korean (KR) ancestry. Subsequent imputation, conditional, haplotype and bioinformatic analyses identified seven potentially functional SLE-predisposing variants. Association with non-synonymous rs17849502, previously reported in EA, was detected in EA, HS and AA (P(EA) = 1.01 × 10(-54), PHS = 3.68 × 10(-10), P(AA) = 0.03); synonymous rs17849501 was similarly significant. These SNPs were monomorphic in KR. Novel associations were detected with coding variants at rs35937854 in AA (PAA = 1.49 × 10(-9)), and rs13306575 in HS and KR (P(HS) = 7.04 × 10(-7), P(KR) = 3.30 × 10(-3)). In KR, a 3-SNP haplotype was significantly associated (P = 4.20 × 10(-7)), implying that SLE predisposing variants were tagged. Significant SNP-SNP interaction (P = 0.02) was detected between rs13306575 and rs17849502 in HS, and a dramatically increased risk (OR = 6.55) with a risk allele at each locus. Molecular modeling predicts that these non-synonymous mutations could disrupt NADPHO complex assembly. The risk allele of rs17849501, located in a conserved transcriptional regulatory region, increased reporter gene activity, suggesting in vivo enhancer function. Our results not only establish allelic heterogeneity within NCF2 associated with SLE, but also emphasize the utility of multi-ethnic cohorts to identify predisposing variants explaining additional phenotypic variance ('missing heritability') of complex diseases like SLE.

  9. Heterogeneous catalytic wet peroxide oxidation systems for the treatment of an industrial pharmaceutical wastewater.

    PubMed

    Melero, J A; Martínez, F; Botas, J A; Molina, R; Pariente, M I

    2009-09-01

    The aim of this work was to assess the treatment of wastewater coming from a pharmaceutical plant through a continuous heterogeneous catalytic wet peroxide oxidation (CWPO) process using an Fe(2)O(3)/SBA-15 nanocomposite catalyst. This catalyst was preliminary tested in a batch stirred tank reactor (STR), to elucidate the influence of significant parameters on the oxidation system, such as temperature, initial oxidant concentration and initial pH of the reaction medium. In that case, a temperature of 80 degrees C using an initial oxidant concentration corresponding to twice the theoretical stoichiometric amount for complete carbon depletion and initial pH of ca. 3 allow TOC degradation of around 50% after 200 min of contact time. Thereafter, the powder catalyst was extruded with bentonite to prepare pellets that could be used in a fixed bed reactor (FBR). Results in the up-flow FBR indicate that the catalyst shows high activity in terms of TOC mineralization (ca. 60% under steady-state conditions), with an excellent use of the oxidant and high stability of the supported iron species. The activity of the catalyst is kept constant, at least, for 55h of reaction. Furthermore, the BOD(5)/COD ratio is increased from 0.20 to 0.30, whereas the average oxidation stage (AOS) changed from 0.70 to 2.35. These two parameters show a high oxidation degree of organic compounds in the outlet effluent, which enhances its biodegradability, and favours the possibility of a subsequent coupling with a conventional biological treatment.

  10. Chemical force spectroscopy in heterogeneous systems: intermolecular interactions involving epoxy polymer, mixed monolayers, and polar solvents.

    PubMed

    Vezenov, Dmitri V; Zhuk, Andrew V; Whitesides, George M; Lieber, Charles M

    2002-09-04

    We used chemical force microscopy (CFM) to study adhesive forces between surfaces of epoxy resin and self-assembled monolayers (SAMs) capable of hydrogen bonding to different extents. The influence of the liquid medium in which the experiments were carried out was also examined systematically. The molecular character of the tip, polymer, and liquid all influenced the adhesion. Complementary macroscopic contact angle measurements were used to assist in the quantitative interpretation of the CFM data. A direct correlation between surface free energy and adhesion forces was observed in mixed alcohol-water solvents. An increase in surface energy from 2 to 50 mJ/m(2) resulted in an increase in adhesion from 4-8 nN to 150-300 nN for tips with radii of 50-150 nm. The interfacial surface energy for identical nonpolar surface groups of SAMs was found not to exceed 2 mJ/m(2). An analysis of adhesion data suggests that the solvent was fully excluded from the zone of contact between functional groups on the tip and sample. With a nonpolar SAM, the force of adhesion increased monotonically in mixed solvents of higher water content; whereas, with a polar SAM (one having a hydrogen bonding component), higher water content led to decreased adhesion. The intermolecular force components theory was used for the interpretation of adhesion force measurements in polar solvents. Competition between hydrogen bonding within the solvent and hydrogen bonding of surface groups and the solvent was shown to provide the main contribution to adhesion forces. We demonstrate how the trends in the magnitude of the adhesion forces for chemically heterogeneous systems (solvents and surfaces) measured with CFM can be quantitatively rationalized using the surface tension components approach. For epoxy polymer, inelastic deformations also contributed heavily to measured adhesion forces.

  11. Allelic heterogeneity in NCF2 associated with systemic lupus erythematosus (SLE) susceptibility across four ethnic populations

    PubMed Central

    Kim-Howard, Xana; Sun, Celi; Molineros, Julio E.; Maiti, Amit K.; Chandru, Hema; Adler, Adam; Wiley, Graham B.; Kaufman, Kenneth M.; Kottyan, Leah; Guthridge, Joel M.; Rasmussen, Astrid; Kelly, Jennifer; Sánchez, Elena; Raj, Prithvi; Li, Quan-Zhen; Bang, So-Young; Lee, Hye-Soon; Kim, Tae-Hwan; Kang, Young Mo; Suh, Chang-Hee; Chung, Won Tae; Park, Yong-Beom; Choe, Jung-Yoon; Shim, Seung Cheol; Lee, Shin-Seok; Han, Bok-Ghee; Olsen, Nancy J.; Karp, David R.; Moser, Kathy; Pons-Estel, Bernardo A.; Wakeland, Edward K.; James, Judith A.; Harley, John B.; Bae, Sang-Cheol; Gaffney, Patrick M.; Alarcón-Riquelme, Marta; Looger, Loren L.; Nath, Swapan K.; Acevedo, Eduardo; Acevedo, Eduardo; La Torre, Ignacio García-De; Maradiaga-Ceceña, Marco A.; Cardiel, Mario H.; Esquivel-Valerio, Jorge A.; Rodriguez-Amado, Jacqueline; Moctezuma, José Francisco; Miranda, Pedro; Perandones, Carlos; Aires, Buenos; Castel, Cecilia; Laborde, Hugo A.; Alba, Paula; Musuruana, Jorge; Goecke, Annelise; Foster, Carola; Orozco, Lorena; Baca, Vicente

    2014-01-01

    Recent reports have associated NCF2, encoding a core component of the multi-protein NADPH oxidase (NADPHO), with systemic lupus erythematosus (SLE) susceptibility in individuals of European ancestry. To identify ethnicity-specific and -robust variants within NCF2, we assessed 145 SNPs in and around the NCF2 gene in 5325 cases and 21 866 controls of European-American (EA), African-American (AA), Hispanic (HS) and Korean (KR) ancestry. Subsequent imputation, conditional, haplotype and bioinformatic analyses identified seven potentially functional SLE-predisposing variants. Association with non-synonymous rs17849502, previously reported in EA, was detected in EA, HS and AA (PEA = 1.01 × 10−54, PHS = 3.68 × 10−10, PAA = 0.03); synonymous rs17849501 was similarly significant. These SNPs were monomorphic in KR. Novel associations were detected with coding variants at rs35937854 in AA (PAA = 1.49 × 10−9), and rs13306575 in HS and KR (PHS = 7.04 × 10−7, PKR = 3.30 × 10−3). In KR, a 3-SNP haplotype was significantly associated (P = 4.20 × 10−7), implying that SLE predisposing variants were tagged. Significant SNP–SNP interaction (P = 0.02) was detected between rs13306575 and rs17849502 in HS, and a dramatically increased risk (OR = 6.55) with a risk allele at each locus. Molecular modeling predicts that these non-synonymous mutations could disrupt NADPHO complex assembly. The risk allele of rs17849501, located in a conserved transcriptional regulatory region, increased reporter gene activity, suggesting in vivo enhancer function. Our results not only establish allelic heterogeneity within NCF2 associated with SLE, but also emphasize the utility of multi-ethnic cohorts to identify predisposing variants explaining additional phenotypic variance (‘missing heritability’) of complex diseases like SLE. PMID:24163247

  12. 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.

  13. Electron localization in a mixed-valence diniobium benzene complex

    DOE PAGES

    Gianetti, Thomas L.; Nocton, Grégory; Minasian, Stefan G.; ...

    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

  14. 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…

  15. Mixed-valence hydroxides as bioorganic host minerals

    NASA Technical Reports Server (NTRS)

    Kuma, K.; Paplawsky, W.; Gedulin, B.; Arrhenius, G.

    1989-01-01

    A range of naturally occurring divalent-trivalent metal cation hydroxides and modified artifical analogs have been synthesized and characterized. Structural and chemical properties of these minerals, determining their capability to selectively concentrate, order and alter molecules of prebiotic interest, include their anion exchange capacity and specificity, photochemical reactivity, production of nascent hydrogen, and catalytic efficiency. Properties relevant to these functions have been investigated and are discussed.

  16. 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…

  17. 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.

  18. 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.

  19. 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.

  20. Application of a "black body" like reactor for measurements of quantum yields of photochemical reactions in heterogeneous systems.

    PubMed

    Emeline, A V; Zhang, X; Jin, M; Murakami, T; Fujishima, A

    2006-04-13

    We report for the first time an experimental application of the concept of a "black body" like reactor to measure quantum yields (Phi) of photochemical reactions in liquid-solid heterogeneous systems. A major advantage of this new method is its simplicity since the fractions of reflected and transmitted light are negligible due to reactor geometry and high optical density of the heterogeneous systems. The average quantum yield of a test reaction (phenol photodegradation) over TiO(2) (Degussa P25) as determined by this method was 0.14, identical to the quantum yield measured earlier for this same reaction under similar conditions by Salinaro and Serpone. We also report the quantum yield of phenol photodegradation over N-doped TiO(2) during photoexcitation at the fundamental absorption band (lambda = 365 nm; Phi = 0.12) and at the N-doping induced extrinsic absorption band (lambda = 436 nm; Phi = 0.08) of the photocatalyst.

  1. 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

  2. Statistical analysis of liquid seepage in partially saturated heterogeneous fracture systems

    SciTech Connect

    Liou, Tai -Sheng

    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

  3. 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.

  4. 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.

  5. 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.

  6. Fundamental Study of the Delivery of Nanoiron to DNAPL Source Zones in Naturally Heterogeneous Field Systems

    DTIC Science & Technology

    2012-09-01

    physical and chemical principles controlling colloid transport (e.g. particle-particle interactions , fluid velocity, grain/pore size). Particle and...NZVI in DNAPL contaminated zones of a naturally heterogeneous subsurface where the free phase is entrapped in a complex architecture and 2) understand... interactions , fluid velocity, grain/pore size). Particle and environmental factors affecting NZVI reactivity and the ability to provide DNAPL

  7. No aging bias favoring memory for positive material: evidence from a heterogeneity-homogeneity list paradigm using emotionally toned words.

    PubMed

    Grühn, Daniel; Smith, Jacqui; Baltes, Paul B

    2005-12-01

    Some authors argue for a memory advantage of older adults for positively toned material. To investigate the contribution of selective processing to a positivity effect, the authors investigated young (n = 72, aged 18 to 31) and older (n = 72, aged 64 to 75) adults' memory for emotionally toned words using a multitrial paradigm that compares performance for heterogeneous (mixed valence) and homogeneous (single valence) lists. Regarding the age comparison, there was no evidence for an aging bias favoring positive material. Moreover, older adults' memory was less affected by emotion-based processing prioritization. Although there was no support for age-specific processing biases in memory for emotionally toned words, the findings are consistent with proposals that negative information receives processing priority in some contexts. Possible limits to the generalizability of the present findings (e.g., to nonverbal material) are discussed.

  8. 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

  9. 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

  10. 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.

  11. 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 l