1,580 research outputs found

    Spin resonance in the superconducting state of Li1−x_{1-x}Fex_{x}ODFe1−y_{1-y}Se observed by neutron spectroscopy

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    We have performed inelastic neutron scattering measurements on a powder sample of the superconductor lithium iron selenide hydroxide Li1−x_{1-x}Fex_{x}ODFe1−y_{1-y}Se (x≃0.16,y≃0.02x \simeq 0.16, y \simeq 0.02, Tc=41T_{\rm c} = 41\,K). The spectrum shows an enhanced intensity below TcT_{\rm c} over an energy range 0.64×2Δ<E<2Δ0.64\times2\Delta < E < 2\Delta, where Δ\Delta is the superconducting gap, with maxima at the wave vectors Q1≃1.46Q_1 \simeq 1.46\,\AA−1^{-1} and Q2≃1.97Q_2 \simeq 1.97\,\AA−1^{-1}. The behavior of this feature is consistent with the spin resonance mode found in other unconventional superconductors, and strongly resembles the spin resonance observed in the spectrum of the molecular-intercalated iron selenide, Li0.6_{0.6}(ND2_{2})0.2_{0.2}(ND3_{3})0.8_{0.8}Fe2_{2}Se2_{2}. The signal can be described with a characteristic two-dimensional wave vector (π,0.67π)(\pi, 0.67\pi) in the Brillouin zone of the iron square lattice, consistent with the nesting vector between electron Fermi sheets

    Nuclear Magnetic Resonance and Impedance Spectroscopy Studies on Lithium Ion Diffusion in γ-LiAlO2

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    In this work we show conductivity spectra of γ-LiAlO2 single crystals purchased from CrysTec and microcrystalline powder prepared by solid state synthesis

    EU-Rotate_N – a decision support system – to predict environmental and economic consequences of the management of nitrogen fertiliser in crop rotations

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    A model has been developed which assesses the economic and environmental performance of crop rotations, in both conventional and organic cropping, for over 70 arable and horticultural crops, and a wide range of growing conditions in Europe. The model, though originally based on the N_ABLE model, has been completely rewritten and contains new routines to simulate root development, the mineralisation and release of nitrogen (N) from soil organic matter and crop residues, and water dynamics in soil. New routines have been added to estimate the effects of sub-optimal rates of N and spacing on the marketable outputs and gross margins. The model provides a mechanism for generating scenarios to represent a range of differing crop and fertiliser management strategies which can be used to evaluate their effects on yield, gross margin and losses of nitrogen through leaching. Such testing has revealed that nitrogen management can be improved and that there is potential to increase gross margins whilst reducing nitrogen losses

    Marine Boundary Layer Clouds Associated with Coastally Trapped Disturbances: Observations and Model Simulations

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    This work has been accepted to Journal of Atmospheric Sciences. The AMS does not guarantee that the copy provided here is an accurate copy of the final published work.Modeling marine low clouds and fog in coastal environments remains an outstanding challenge due to the inherently complex ocean–land–atmosphere system. This is especially important in the context of global circulation models due to the profound radiative impact of these clouds. This study utilizes aircraft and satellite measurements, in addition to numerical simulations using the Weather Research and Forecasting (WRF) Model, to examine three well-observed coastally trapped disturbance (CTD) events from June 2006, July 2011, and July 2015. Cloud water-soluble ionic and elemental composition analyses conducted for two of the CTD cases indicate that anthropogenic aerosol sources may impact CTD cloud decks due to synoptic-scale patterns associated with CTD initiation. In general, the dynamics and thermodynamics of the CTD systems are well represented and are relatively insensitive to the choice of physics parameterizations; however, a set of WRF simulations suggests that the treatment of model physics strongly influences CTD cloud field evolution. Specifically, cloud liquid water path (LWP) is highly sensitive to the choice of the planetary boundary layer (PBL) scheme; in many instances, the PBL scheme affects cloud extent and LWP values as much as or more than the microphysics scheme. Results suggest that differences in the treatment of entrainment and vertical mixing in the Yonsei University (nonlocal) and Mellor–Yamada–Janjić (local) PBL schemes may play a significant role. The impact of using different driving models—namely, the North American Mesoscale Forecast System (NAM) 12-km analysis and the NCEP North American Regional Reanalysis (NARR) 32-km products—is also investigated

    Marine Boundary Layer Clouds Associated with Coastally Trapped Disturbances: Observations and Model Simulations

    Get PDF
    Modeling marine low clouds and fog in coastal environments remains an outstanding challenge due to the inherently complex ocean–land–atmosphere system. This is especially important in the context of global circulation models due to the profound radiative impact of these clouds. This study utilizes aircraft and satellite measurements, in addition to numerical simulations using the Weather Research and Forecasting (WRF) Model, to examine three well-observed coastally trapped disturbance (CTD) events from June 2006, July 2011, and July 2015. Cloud water-soluble ionic and elemental composition analyses conducted for two of the CTD cases indicate that anthropogenic aerosol sources may impact CTD cloud decks due to synoptic-scale patterns associated with CTD initiation. In general, the dynamics and thermodynamics of the CTD systems are well represented and are relatively insensitive to the choice of physics parameterizations; however, a set of WRF simulations suggests that the treatment of model physics strongly influences CTD cloud field evolution. Specifically, cloud liquid water path (LWP) is highly sensitive to the choice of the planetary boundary layer (PBL) scheme; in many instances, the PBL scheme affects cloud extent and LWP values as much as or more than the microphysics scheme. Results suggest that differences in the treatment of entrainment and vertical mixing in the Yonsei University (nonlocal) and Mellor–Yamada–Janjić (local) PBL schemes may play a significant role. The impact of using different driving models—namely, the North American Mesoscale Forecast System (NAM) 12-km analysis and the NCEP North American Regional Reanalysis (NARR) 32-km products—is also investigated
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