31,601 research outputs found

    Stripe phases in the two-dimensional Falicov-Kimball model

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    The observation of charge stripe order in the doped nickelate and cuprate materials has motivated much theoretical effort to understand the underlying mechanism of the stripe phase. Numerical studies of the Hubbard model show two possibilities: (i) stripe order arises from a tendency toward phase separation and its competition with the long-range Coulomb interaction or (ii) stripe order inherently arises as a compromise between itinerancy and magnetic interactions. Here we determine the restricted phase diagrams of the two-dimensional Falicov-Kimball model and see that it displays rich behavior illustrating both possibilities in different regions of the phase diagram.Comment: (5 pages, 3 figures

    A Selected Ion Flow Tube Study of the Reactions of Several Cations with the Group 6B Hexafluorides SF6, SeF6, and TeF6

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    The first investigation of the ion chemistry of SeF6_6 and TeF6_6 is presented. Using a selected ion flow tube, the thermal rate coefficients and ion product distributions have been determined at 300 K for the reactions of fourteen atomic and molecular cations, namely H3_3O+^+, CF3+_3^+, CF+^+, CF2+_2^+, H2_2O+^+, N2_2O+^+, O+^+, CO2+_2^+, CO+^+, N+^+, N2+_2^+, Ar+^+, F+^+ and Ne+^+ (in order of increasing recombination energy), with SeF6_6 and TeF6_6. The results are compared with those from the reactions of these ions with SF6_6, for which the reactions with CF+^+, CF2+_2^+, N2_2O+^+ and F+^+ are reported for the first time. Several distinct processes are observed amongst the large number of reactions studied, including dissociative charge transfer, and F^-, F, F2_2^- and F2_2 abstraction from the neutral reactant molecule to the reagent ion. The dissociative charge transfer channels are discussed in relation to vacuum ultraviolet photoelectron and threshold photoelectron-photoion coincidence spectra of XF6_6 (X = S, Se, and Te). For reagent ions whose recombination energies lie between the first dissociative ionisation limit, XF6_6 \rightarrow XF5+_5^+ + F + e^-, and the onset of ionisation of the XF6_6 molecule, the results suggest that if dissociative charge transfer occurs, it proceeds via an intimate encounter. For those reagent ions whose recombination energies are greater than the onset of ionisation, long-range electron transfer may occur depending on whether certain physical factors apply, for example non-zero Franck-Condon overlap. From the reaction kinetics, limits for the heats of formation of SeF4_4, SeF5_5, TeF4_4 and TeF5_5 at 298 K have been obtained; Δf\Delta_fHo^o(SeF4_4) < -369 kJ mol1^{-1}, Δf\Delta_fHo^o(SeF5_5) < -621 kJ mol1^{-1}, Δf\Delta_fHo^o(TeF4_4) > -570 kJ mol1^{-1}, and Δf\Delta_fHo^o(TeF5_5) < -822 kJ mol1^{-1}

    Pengaruh Penerapan Anggraran Berbasis Kinerja, Sistem Informasi Pengelolaan Keuangan Daerah dan Kualitas Sumber Daya Manusia terhadap Kinerja Skpd Provinsi Riau (Studi Empiris pada Skpd Provinsi Riau)

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    This research aims to prove the effect of Application of Performance-Based Budgeting to performance SKPD Riau province, then Effect of System of Financial Management Information on the performance of skpd Riau province, and the Effect of Quality of Human Resources to performance SKPD Riau province. The population in this study is the Regional Working Units (on education) in the Riau provincial government on education in 38 provinces comprising Region 1 Secretariat Riau, Riau Province Inspectorate 1, 1 Secretary DPRD Riau, Riau KORPRI 1 Secretary, Civil Service Police Unit 1, 2 Hospital (Hospital and RSJ), Agency 14, and 17 Department. Samples from this study are echelon III and IV at Department and Agency of Riau Province by 86 people. Analysis of the data in this study using tools SPSS software version 17. The results showed that the Application of Performanced-Based Budgeting, System of Financial Management Information, and Quality of Human Resource affect the Performance SKPD Riau province.Keywords: Performanced-Based Budgeting, financial, System of Financial Information area, Performanced and Human Resource to Performanced

    To Duckweeds (\u3cem\u3eLandoltia punctata\u3c/em\u3e), Nanoparticulate Copper Oxide is More Inhibitory than the Soluble Copper in the Bulk Solution

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    CuO nanoparticles (CuO-NP) were synthesized in a hydrogen diffusion flame. Particle size and morphology were characterized using scanning mobility particle sizing, Brunauer–Emmett–Teller analysis, dynamic light scattering, and transmission electron microscopy. The solubility of CuO-NP varied with both pH and presence of other ions. CuO-NP and comparable doses of soluble Cu were applied to duckweeds, Landoltia punctata. Growth was inhibited 50% by either 0.6 mg L−1 soluble copper or by 1.0 mg L−1 CuO-NP that released only 0.16 mg L−1 soluble Cu into growth medium. A significant decrease of chlorophyll was observed in plants stressed by 1.0 mg L−1 CuO-NP, but not in the comparable 0.2 mg L−1 soluble Cu treatment. The Cu content of fronds exposed to CuO-NP is four times higher than in fronds exposed to an equivalent dose of soluble copper, and this is enough to explain the inhibitory effects on growth and chlorophyll content

    Electroweak Theory Without Higgs Bosons

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    A perturbative SU(2)_L X U(1)_Y electroweak theory containing W, Z, photon, ghost, lepton and quark fields, but no Higgs or other fields, gives masses to W, Z and the non-neutrino fermions by means of an unconventional choice for the unperturbed Lagrangian and a novel method of renormalisation. The renormalisation extends to all orders. The masses emerge on renormalisation to one loop. To one loop the neutrinos are massless, the A -> Z transition drops out of the theory, the d quark is unstable and S-matrix elements are independent of the gauge parameter xi.Comment: 27 pages, LaTex, no figures; revised for publication; accepted by Int. J. Mod. Phys. A; includes biographical note on A. F. Nicholso
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