256,546 research outputs found

    Sweeping the Space of Admissible Quark Mass Matrices

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    We propose a new and efficient method of reconstructing quark mass matrices from their eigenvalues and a complete set of mixing observables. By a combination of the principle of NNI (nearest neighbour interaction) bases which are known to cover the general case, and of the polar decomposition theorem that allows to convert arbitrary nonsingular matrices to triangular form, we achieve a parameterization where the remaining freedom is reduced to one complex parameter. While this parameter runs through the domain bounded by a circle with radius R determined by the up-quark masses around the origin in the complex plane one sweeps the space of all mass matrices compatible with the given set of data.Comment: 18 page

    Relative influence of shredders and fungi on leaf litter decomposition along a river altitudinal gradient

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    We compared autumn decomposition rates of European alder leaves at four sites along the Lasset–Hers River system, southern France, to test whether changes in litter decomposition rates from upstream (1,300 m elevation) to downstream (690 m) could be attributed to temperature-driven differences in microbial growth, shredder activity, or composition of the shredder community. Alder leaves lost 75–87% of original mass in 57 days, of which 46–67% could be attributed to microbial metabolism and 8–29% to shredder activity, with no trend along the river. Mass loss rates in both fine-mesh (excluding shredders) and coarse-mesh (including shredders) bags were faster at warm, downstream sites (mean daily temperature 7–8°C) than upstream (mean 1–2°C), but the differ- ence disappeared when rates were expressed in heat units to remove the temperature effect. Mycelial biomass did not correlate with mass loss rates. Faster mass loss rates upstream, after temperature correction, evidently arise from more efficient shredding by Nemourid stoneflies than by the Leuctra-dominated assemblage downstream. The influence of water temperature on decomposition rate is therefore expressed both directly, through microbial metabolism, and indirectly, through the structure of shredder commu- nities. These influences are evident even in cold water where temperature variation is small

    Role of anharmonic phonon scattering in the spectrally decomposed thermal conductance at planar interfaces

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    Detailed understanding of vibrational heat transfer mechanisms between solids is essential for the efficient thermal engineering and control of nanomaterials. We investigate the frequency dependence of anharmonic scattering and interfacial thermal conduction between two acoustically mismatched solids in planar contact by calculating the spectral decomposition of the heat current flowing through an interface between two materials. The calculations are based on analyzing the correlations of atomic vibrations using the data extracted from non-equilibrium molecular dynamics simulations. Inelastic effects arising from anharmonic interactions are shown to significantly facilitate heat transfer between two mass-mismatched face-centered cubic lattices even at frequencies exceeding the cut-off frequency of the heavier material due to (i) enhanced dissipation of evanescent vibrational modes and (ii) frequency-doubling and frequency-halving three-phonon energy transfer processes at the interface. The results provide substantial insight into interfacial energy transfer mechanisms especially at high temperatures, where inelastic effects become important and other computational methods are ineffective.Comment: minor changes to v

    Streaming visualisation of quantitative mass spectrometry data based on a novel raw signal decomposition method

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    As data rates rise, there is a danger that informatics for high-throughput LC-MS becomes more opaque and inaccessible to practitioners. It is therefore critical that efficient visualisation tools are available to facilitate quality control, verification, validation, interpretation, and sharing of raw MS data and the results of MS analyses. Currently, MS data is stored as contiguous spectra. Recall of individual spectra is quick but panoramas, zooming and panning across whole datasets necessitates processing/memory overheads impractical for interactive use. Moreover, visualisation is challenging if significant quantification data is missing due to data-dependent acquisition of MS/MS spectra. In order to tackle these issues, we leverage our seaMass technique for novel signal decomposition. LC-MS data is modelled as a 2D surface through selection of a sparse set of weighted B-spline basis functions from an over-complete dictionary. By ordering and spatially partitioning the weights with an R-tree data model, efficient streaming visualisations are achieved. In this paper, we describe the core MS1 visualisation engine and overlay of MS/MS annotations. This enables the mass spectrometrist to quickly inspect whole runs for ionisation/chromatographic issues, MS/MS precursors for coverage problems, or putative biomarkers for interferences, for example. The open-source software is available from http://seamass.net/viz/

    Performance Evaluation of a Full-Scale Deep U-Tube Utilizing Ozonated Oxygen as the Process Gas for Treating Drinking Water

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    A deep U-tube for treating drinking water is composed of a coaxial inner tube serving as an efficient concurrent down-flow ozone dissolver and an outer column carrying out reactions between ozone and organic substances dissolved in the water after sedimentation treatment. In the present study, we developed a novel simulation model of the U-tube reactor, assuming that the U-tube is composed of a plug flow section (inner tube) followed by a tanks-in-series section (outer bubble column) and taking into account the reactions involved, and the effects of the hydrostatic pressurization on the flow and absorption equilibrium for the ozone and inactive gases in developing the mass balance models. We constructed an algorithm to evaluate the U-tube reactor performance based on the mass balance models. The hydrodynamics and mass transfer characteristics in the inner tube were measured and their correlations were incorporated in the simulation model. Available literature data and correlations on the rates of reactions between ozone and organic substances, the gas-liquid equilibrium for the active and inactive gases and the fluid mixing properties are also incorporated in the simulation model. The simulation results well explained the available data on the ozone absorption efficiency and the removal efficiency of odorous material (2-MIB) in a pilot plant and a real U-tube reactor. It is found that the ozone absorption is practically a single function of the gas/liquid ratio, while the decomposition efficiency of 2-MIB is a single function of the ozone dose for the water quantity to be treated
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