1,478 research outputs found

    Hanford radiochemical site decommissioning demonstration program

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    A program is proposed for the innovation, development, and demonstration of technologies necessary to decommission the Hanford radiochemical plant area to the extent that the sites can have unrestricted public access. The five tasks selected for development and demonstration of restoration techniques were restoration of a burial ground, decommissioning of a separations plant, restoration of a separations plant waste interim storage tank farm, restoration of a liquid disposal area, and disposal of large contaminated equipment. Process development requirements are tabulated and discussed. A proposed schedule and estimated costs are given. (JSR

    NorKing Russet, A New Potato Variety

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    This article gives background into the breeding history that lead to the potato variety named Nor King Russet. It resulted from a cross between Nooksack and ND9567-2Russ. Nooksack is a russet variety grown for processing (french fry) in the northwestern states and ND9567-2Russ resulted from a cross between two number selections that have Norchip and B5141-6 in their pedigrees

    Numerical Study of the Spin-Flop Transition in Anisotropic Spin-1/2 Antiferromagnets

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    Magnetization processes of the spin-1/2 antiferromagnetic XXZXXZ model in two and three spatial dimensions are studied using quantum Monte Carlo method based on stochastic series expansions. Recently developed operator-loop algorithm enables us to show a clear evidence of the first-order phase transition in the presence of an external magnetic field. Phase diagrams of closely related systems, hard core bosons with nearest-neighbor repulsions, are also discussed focusing on possibilities of phase-separated and supersolid phases.Comment: 4 pages, Revtex version 4, with 4 figures embedded, To appear in Phys. Rev.

    Molecular analysis of the distribution and phylogeny of the soxB gene among sulfur-oxidizing bacteria - evolution of the Sox sulfur-oxidizing enzyme system

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    The soxB gene encodes the SoxB component of the periplasmic thiosulfate-oxidizing Sox enzyme complex, which has been proposed to be widespread among the various phylogenetic groups of sulfur-oxidizing bacteria (SOB) that convert thiosulfate to sulfate with and without the formation of sulfur globules as intermediate. Indeed, the comprehensive genetic and genomic analyses presented in the present study identified the soxB gene in 121 phylogenetically and physiologically divergent SOB, including several species for which thiosulfate utilization has not been reported yet. In first support of the previously postulated general involvement of components of the Sox enzyme complex in the thiosulfate oxidation process of sulfur-storing SOB, the soxB gene was detected in all investigated photo- and chemotrophic species that form sulfur globules during thiosulfate oxidation (Chromatiaceae, Chlorobiaceae, Ectothiorhodospiraceae, Thiothrix, Beggiatoa, Thiobacillus, invertebrate symbionts and free-living relatives). The SoxB phylogeny reflected the major 16S rRNA gene-based phylogenetic lineages of the investigated SOB, although topological discrepancies indicated several events of lateral soxB gene transfer among the SOB, e.g. its independent acquisition by the anaerobic anoxygenic phototrophic lineages from different chemotrophic donor lineages. A putative scenario for the proteobacterial origin and evolution of the Sox enzyme system in SOB is presented considering the phylogenetic, genomic (sox gene cluster composition) and geochemical data

    Fluctuating Nematic Elastomer Membranes: a New Universality Class

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    We study the flat phase of nematic elastomer membranes with rotational symmetry spontaneously broken by in-plane nematic order. Such state is characterized by a vanishing elastic modulus for simple shear and soft transverse phonons. At harmonic level, in-plane orientational (nematic) order is stable to thermal fluctuations, that lead to short-range in-plane translational (phonon) correlations. To treat thermal fluctuations and relevant elastic nonlinearities, we introduce two generalizations of two-dimensional membranes in a three dimensional space to arbitrary D-dimensional membranes embedded in a d-dimensional space, and analyze their anomalous elasticities in an expansion about D=4. We find a new stable fixed point, that controls long-scale properties of nematic elastomer membranes. It is characterized by singular in-plane elastic moduli that vanish as a power-law eta_lambda=4-D of a relevant inverse length scale (e.g., wavevector) and a finite bending rigidity. Our predictions are asymptotically exact near 4 dimensions.Comment: 18 pages, 4 eps figures. submitted to PR

    Quantum Phase Transitions and Conserved Charges

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    The constraints on the scaling properties of conserved charge densities in the vicinity of a zero temperature (TT), second-order quantum phase transition are studied. We introduce a generalized Wilson ratio, characterizing the non-linear response to an external field, HH, coupling to any conserved charge, and argue that it is a completely universal function of H/TH/T: this is illustrated by computations on model systems. We also note implications for transitions where the order parameter is a conserved charge (as in a T=0T=0 ferromagnet-paramagnet transition).Comment: 19 pages, REVTEX 3.0, 8 uuencoded Postscript figues appended, YCTP-xxx

    Universal Magnetic Properties of La2δSrδCuO4La_{2-\delta} Sr_{\delta} Cu O_4 at Intermediate Temperatures

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    We present the theory of two-dimensional, clean quantum antiferromagnets with a small, positive, zero temperature (TT) stiffness ρs\rho_s, but with the ratio kBT/ρsk_B T / \rho_s arbitrary. Universal scaling forms for the uniform susceptibility (χu\chi_u), correlation length(ξ\xi), and NMR relaxation rate (1/T11/T_1) are proposed and computed in a 1/N1/N expansion and by Mont\'{e}-Carlo simulations. For large kBT/ρsk_B T/\rho_s, χu(T)/T\chi_u (T)/T and Tξ(T)T\xi(T) asymptote to universal values, while 1/T1(T)1/T_{1}(T) is nearly TT-independent. We find good quantitative agreement with experiments and some numerical studies on La2δSrδCuO4La_{2-\delta} Sr_{\delta} Cu O_4.Comment: 14 pages, REVTEX, 1 postscript figure appende

    Adaptation of Autocatalytic Fluctuations to Diffusive Noise

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    Evolution of a system of diffusing and proliferating mortal reactants is analyzed in the presence of randomly moving catalysts. While the continuum description of the problem predicts reactant extinction as the average growth rate becomes negative, growth rate fluctuations induced by the discrete nature of the agents are shown to allow for an active phase, where reactants proliferate as their spatial configuration adapts to the fluctuations of the catalysts density. The model is explored by employing field theoretical techniques, numerical simulations and strong coupling analysis. For d<=2, the system is shown to exhibits an active phase at any growth rate, while for d>2 a kinetic phase transition is predicted. The applicability of this model as a prototype for a host of phenomena which exhibit self organization is discussed.Comment: 6 pages 6 figur
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