1,000 research outputs found

    MPAS-Albany Land Ice (MALI): a variable-resolution ice sheet model for Earth system modeling using Voronoi grids

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    We introduce MPAS-Albany Land Ice (MALI) v6.0, a new variable-resolution land ice model that uses unstructured Voronoi grids on a plane or sphere. MALI is built using the Model for Prediction Across Scales (MPAS) framework for developing variable-resolution Earth system model components and the Albany multi-physics code base for the solution of coupled systems of partial differential equations, which itself makes use of Trilinos solver libraries. MALI includes a three-dimensional first-order momentum balance solver (Blatter–Pattyn) by linking to the Albany-LI ice sheet velocity solver and an explicit shallow ice velocity solver. The evolution of ice geometry and tracers is handled through an explicit first-order horizontal advection scheme with vertical remapping. The evolution of ice temperature is treated using operator splitting of vertical diffusion and horizontal advection and can be configured to use either a temperature or enthalpy formulation. MALI includes a mass-conserving subglacial hydrology model that supports distributed and/or channelized drainage and can optionally be coupled to ice dynamics. Options for calving include eigencalving, which assumes that the calving rate is proportional to extensional strain rates. MALI is evaluated against commonly used exact solutions and community benchmark experiments and shows the expected accuracy. Results for the MISMIP3d benchmark experiments with MALI's Blatter–Pattyn solver fall between published results from Stokes and L1L2 models as expected. We use the model to simulate a semi-realistic Antarctic ice sheet problem following the initMIP protocol and using 2&thinsp;km resolution in marine ice sheet regions. MALI is the glacier component of the Energy Exascale Earth System Model (E3SM) version 1, and we describe current and planned coupling to other E3SM components.</p

    DFT investigation of 3d transition metal NMR shielding tensors in diamagnetic systems using the gauge-including projector augmented-wave method

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    We present a density functional theory based method for calculating NMR shielding tensors for 3d transition metal nuclei using periodic boundary conditions. Calculations employ the gauge-including projector augmented-wave pseudopotentials method. The effects of ultrasoft pseudopotential and induced approximations on the second-order magnetic response are intensively examined. The reliability and the strength of the approach for 49Ti and 51V nuclei is shown by comparison with traditional quantum chemical methods, using benchmarks of finite organometallic systems. Application to infinite systems is validated through comparison to experimental data for the 51V nucleus in various vanadium oxide based compounds. The successful agreement obtained for isotropic chemical shifts contrasts with full estimation of the shielding tensor eigenvalues, revealing the limitation of pure exchange-correlation functionals compared to their exact-exchange corrected analogues.Comment: 56 page

    Serumproteinbindung von ACTH

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    3H- 1–23-Corticotropin wurde an Dextrangel (Sephadex G-25) gebunden und konnte durch Serumproteine, Albumin oder 0,1 N HCl eluiert werden. Mittels Dextrangelfiltration wurde gefunden, daß3H-ACTH kompetitiv an Serumproteine (Albumin) und Dextrangel gebunden wurde. Auch für natürliches Schweine-ACTH und endogenes ACTH in Patientenplasma (Adrenalektomie) wurde mittels biologischer ACTH-Bestimmung die Bindung von ACTH an Proteine bestätigt.3H- 1–23 corticotropin was bound to dextran gel (sephadex G-25) and was eluted by either serum proteins, albumin or 0.1 N HCl. Competitive binding of3H-ACTH to serum proteins (albumin) and dextran gel was shown by dextran gel filtration. Likewise natural ACTH (pig) and endogenous ACTH from plasma of an adrenalectomized patient were shown to be partly protein bound using biological ACTH-assay
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