Equatorial symmetry breaking and the loss of dipolarity in rapidly rotating dynamos     

Ferran Garcia  Ludivine Oruba  Emmanuel Dormy 《地球物理与天体物理流体动力学》2017,111(5):380-393

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The Vaca Muerta mesosiderite: The path under which Fe-Ni alloy ±C phases could have formed     

M. E. Varela  S.-L. Hwang  P. Shen  L. N. Garcia  M. Saavedra  T. Maruoka  M. Bose 《Meteoritics & planetary science》2024,59(3):421-434

The combined SEM and TEM studies on the metal (Fe-Ni alloy ±C) portion of the Vaca Muerta mesosiderite reveal structural and compositional evidence at micro to nanoscale, which sheds light on the solidification of taenite + graphite as a cement, and later solid-state precipitation process for the kamacite formation as grain boundary allotriomorph. Besides, it is proposed that the graphite veinlets formed through a complex partial melting process followed by a solidification toward the final eutectic transient coupled with the solid-state precipitation and later decomposition ordering of taenite. The presence of defects and taenite in graphite signal formation in a liquid environment. The δ¹³C values of graphite in the graphite-rich areas (e.g., ranging from −0.8 ± 1.7‰ to +15.3 ± 2.5‰) suggest a short-circuit diffusion path for C isotope fractionation.  相似文献   

Dispersal and deposition of suspended sediment on the shelf off the Tagus and Sado estuaries, S.W. Portugal     

J. M. Jouanneau  C. Garcia  A. Oliveira  A. Rodrigues  J. A. Dias  O. Weber 《Progress in Oceanography》1998,42(1-4)

The Portuguese margin in front of the Tagus and Sado rivers is characterized by a narrow shelf incised by numerous canyons and by a large mud deposit. The two estuaries that feed this continental margin have distinct impact. The suspended particulate matter concentration values in the mouth of the Tagus are four times higher than in the Sado. During the summer the surface nepheloid layer is always larger than during the winter when it is restricted near the mouth of the estuary. This nepheloid layer may reach 30 km in length extending westward. The bottom nepheloid layer usually shows higher nephelometer values, and has a typical distribution: it is usually diverted southward in the direction of the Lisbon Submarine Canyon. We estimate the amount of suspended matter being discharged annually from the Tagus estuary to be between 0.4 and 1×10⁶ t. The area covered by fine deposits is about 560 km². Hence the thickness of sediments deposited annually should be between 0.07 and 0.18 cm. The sedimentation rates calculated from the ²¹⁰Pb excess vary between 0.16 and 2.13 cm y⁻¹ which correspond to the maximum rate. For a layer of 1 cm thick, 81,000 t of particulate organic carbon (POC) should be trapped. That would represent, with a minimum sedimentation rate between 0.07 and 0.18 cm y⁻¹, an entrapment of 6000–15,000 t POC y⁻¹. The trace metals content of box core samples clearly shows the anthropogenic impact in the uppermost level (5 cm thick) in the Tagus estuary and in all the sedimentary deposits (15 cm thick) on the shelf muddy area. Despite the narrowness of the shelf, a significant part of continental fluxes fails to reach the deep ocean.  相似文献   

Assessment of susceptibility to landslides through geographic information systems and the logistic regression model     

Riegel  Roberta Plangg  Alves  Darlan Daniel  Schmidt  Bruna Caroline  de Oliveira  Guilherme Garcia  Haetinger  Claus  Osório  Daniela Montanari Migliavacca  Rodrigues  Marco Antônio Siqueira  de Quevedo  Daniela Muller 《Natural Hazards》2020,103(1):497-511

Natural Hazards - The increase in the frequency of natural disasters in recent years and its consequent social, economic and environmental impacts make it possible to prioritize areas of risk as an...  相似文献   

Duality rotations and type D solutions of Einstein-Born-Infeld theory     

H. Salazar  A. Garcia D.  J. F. Plebanski 《Astronomische Nachrichten》1986,307(5):327-333

Within the non-linear electrodynamics of Born-Infeld type, constrained by the condition that admits the freedom of the duality rotations the explicit type D solutions, which generalize the charged Taub-NUT metric with cosmological constant, are constructed. The obtained type D solution exhausts all solutions within the considered class, assumed that the real eigenvectors of the electromagnetic field are aligned along the geodesic and shear-free principa null directions.  相似文献