15,811 research outputs found
Avaliação do impacto ambiental da implantação de sistemas silvipastoris em propriedades familiares no estado de Rondônia, Brasil.
O objetivo desse estudo foi avaliar o impacto ambiental da implantação de sistemas silvipastoris (SSPs) em pequenas propriedades no Estado de Rondônia, Brasil.bitstream/item/46573/1/cot356-sistemassilvipastoris.pd
Magnetoelectric effects in an organo-metallic quantum magnet
We observe a bilinear magnetic field-induced electric polarization of 50 in single crystals of NiCl-4SC(NH) (DTN). DTN forms a
tetragonal structure that breaks inversion symmetry, with the highly polar
thiourea molecules all tilted in the same direction along the c-axis.
Application of a magnetic field between 2 and 12 T induces canted
antiferromagnetism of the Ni spins and the resulting magnetization closely
tracks the electric polarization. We speculate that the Ni magnetic forces
acting on the soft organic lattice can create significant distortions and
modify the angles of the thiourea molecules, thereby creating a magnetoelectric
effect. This is an example of how magnetoelectric effects can be constructed in
organo-metallic single crystals by combining magnetic ions with electrically
polar organic elements.Comment: 3 pages, 3 figure
Model for erosion-deposition patterns
We investigate through computational simulations with a pore network model
the formation of patterns caused by erosion-deposition mechanisms. In this
model, the geometry of the pore space changes dynamically as a consequence of
the coupling between the fluid flow and the movement of particles due to local
drag forces. Our results for this irreversible process show that the model is
capable to reproduce typical natural patterns caused by well known erosion
processes. Moreover, we observe that, within a certain range of porosity
values, the grains form clusters that are tilted with respect to the horizontal
with a characteristic angle. We compare our results to recent experiments for
granular material in flowing water and show that they present a satisfactory
agreement.Comment: 8 pages, 12 figures, submitted to Phys. Rev.
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