A systematic approach to multiphysics extensions of finite-element-based micromagnetic simulations: Nmag

Extensions of the basic micromagnetic model that include effects such as spin-current interaction, diffusion of thermal energy or anisotropic magnetoresistance are often studied by performing simulations that use case-specific ad-hoc extensions of widely used software packages such as OOMMF or Magpar. We present the novel software framework 'Nmag' that handles specifications of micromagnetic systems at a sufficiently abstract level to enable users with little programming experience to automatically translate a description of a large class of dynamical multifield equations plus a description of the system's geometry into a working simulation. Conceptually, this is a step towards a higher-level abstract notation for classical multifield mutliphysics simulations, similar to the change from assembly language to a higher level human-and-machine-readable formula notation for mathematical terms (FORTRAN) half a century ago. We demonstrate the capability of this approach through two examples, showing 1) a reduced dimensionality model coupling two copies of the micromagnetic sector and 2) the computation of a spatial current density distribution for anisotropic magnetoresistance (AMR). For cross-wise validation purposes, we also show how Nmag compares to the OOMMF and Magpar packages on a selected micromagnetic toy system. We furthermore, briefly discuss the limiations of our framework and related conceptual questions

Analysis of magnetoresistance in arrays of connected nano-rings

We study the anisotropic magnetoresistance (AME) of a 2D periodic square array of connected permalloy rings with periodicity of 1m combining experimental and computational techniques. The computational models consists of two parts: 1) the computation of the magnetization and 2) the computation of the current density. For 1), we use standard micromagnetic methods. For 2), we start from a potential difference applied across the sample, compute the resulting electric potential , and subsequently the corresponding current density based on a uniform conductiviy. We take into account the backreaction of the magnetoresistive effects onto the current density by self-consistently computing the current density and conductivity until they converge. We compare the experimentally measured AMR insight into the characteristics of the AMR data. Finally, we demonstrate the importance of taking into account the spatial variation of the current density when computing the AMR

Resveratrol improves TNF-α-induced endothelial dysfunction in a coculture model of a Caco-2 with an endothelial cell line

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Variação do teor de carboidratos solúveis em germoplasma de capim-elefante.

Resumo: O objetivo deste trabalho foi estimar a variação do teor de carboidratos solúveis (BRIX) existente entre 95 acessos de capim elefante (Pennisetum purpureum) do banco de germoplasma da Embrapa Gado de Leite, localizado no campo experimental de Coronel Pacheco. Foram identificados os acessos com maior teor de carboidratos solúveis, bem como avaliado o efeito do aumento da idade da planta sobre a variação da concentração de carboidrato solúvel (Brix). O experimento foi conduzido em blocos ao acaso, com duas repetições, 95 genótipos, duas idades de planta, 70 e 100 dias de crescimento, e análise do teor de carboidratos solúveis em duas secções amostradas à 30 cm da base e na metade do colmo. A análise de variância considerou o modelo de parcela subdividida no tempo, sendo os acessos as parcelas e a idade da planta as subparcelas. As médias foram comparadas pelo teste de Scott e Knott. Observou-se variação no teor de carboidratos solúveis entre os acessos do banco de germoplasma de capim elefante, porém não observou-se efeito significativo do aumento da idade da planta sobre o teor de carboidrato solúvel (Brix). Entretanto, alguns acessos apresentaram interação significativa com aumento ou redução do teor de carboidratos solúveis em decorrência do aumento da idade da planta. Os acessos com maior teor de carboidratos solúveis aos 70 dias e 100 dias de crescimento foram BAG80 (7,48%) e BAG94 (6,90%), enquanto os acessos com menores teores foram os acessos BAG13 (2,35%) e BAG36 (4,08%), respectivamente.Editor Técnico: Leônidas Paixão Passos, Embrapa Gado de Leite

A connexin/ifi30 pathway bridges HSCs with their niche to dampen oxidative stress

Reactive oxygen species (ROS) represent a by-product of metabolism and their excess is toxic for hematopoietic stem and progenitor cells (HSPCs). During embryogenesis, a small number of HSPCs are produced from the hemogenic endothelium, before they colonize a transient organ where they expand, for example the fetal liver in mammals. In this study, we use zebrafish to understand the molecular mechanisms that are important in the caudal hematopoietic tissue (equivalent to the mammalian fetal liver) to promote HSPC expansion. High levels of ROS are deleterious for HSPCs in this niche, however this is rescued by addition of antioxidants. We show that Cx41.8 is important to lower ROS levels in HSPCs. We also demonstrate a new role for ifi30, known to be involved in the immune response. In the hematopoietic niche, Ifi30 can recycle oxidized glutathione to allow HSPCs to dampen their levels of ROS, a role that could be conserved in human fetal liver

Role of magnetic dopants in the phase diagram of Sm1111 pnictides: The Mn case

The deliberate insertion of magnetic Mn dopants in the Fe sites of the optimally-doped SmFeAsO0.88-F0.12 iron-based superconductor can modify in a controlled way its electronic properties. The resulting phase diagram was investigated across a wide range of manganese contents (x) by means of muon-spin spectroscopy (muSR), both in zero- and in transverse fields, respectively, to probe the magnetic and the superconducting order. The pure superconducting phase (at x < 0.03) is replaced by a crossover region at intermediate Mn values (0.03 =< x < 0.08), where superconductivity coexists with static magnetic order. After completely suppressing superconductivity for x = 0.08, a further increase in Mn content reinforces the natural tendency towards antiferromagnetic correlations among the magnetic Mn ions. The sharp drop of Tc and the induced magnetic order in the presence of magnetic disorder/dopants, such as Mn, are both consistent with a recent theoretical model of unconventional superconductors [M. Gastiasoro et al., ArXiv 1606.09495], which includes correlation-enhanced RKKY-couplings between the impurity moments.Comment: 10 pages, 13 figures. Accepted on Physical Review

Anthocyanin composition of young red wine cv. Ruby Cabernet and Syrah: effect of time and storage conditions.

The aim of this study was to evaluate the evolution of anthocyanins in red wines for 12 months of storage in bottles in two different conditions. The wine samples cv. Ruby Cabernet and cv. Syrah (Vitis vinifera L.) used for this study were produced in the Sub-middle São Francisco Valley, in the Northeast Region of Brazil, during the 2013 harvest

Anthocyanin composition of young red wine cv. Ruby Cabernet and Syrah: effect of time and storage conditions.

The aim of this study was to evaluate the evolution of anthocyanins in red wines for 12 months of storage in bottles in two different conditions. The wine samples cv. Ruby Cabernet and cv. Syrah (Vitis vinifera L.) used for this study were produced in the Sub-middle São Francisco Valley, in the Northeast Region of Brazil, during the 2013 harvest