Jovian Auroral Ion Precipitation: X‐Ray Production From Oxygen and Sulfur Precipitation

Many attempts have been made to model X‐ray emission from both bremsstrahlung and ion precipitation into Jupiter's polar caps. Electron bremsstrahlung modeling has fallen short of producing the total overall power output observed by Earth‐orbit‐based X‐ray observatories. Heavy ion precipitation was able to reproduce strong X‐ray fluxes, but the proposed incident ion energies were very high ( urn:x-wiley:jgra:media:jgra55396:jgra55396-math-00011 MeV per nucleon). Now with the Juno spacecraft at Jupiter, there have been many measurements of heavy ion populations above the polar cap with energies up to 300–400 keV per nucleon (keV/u), well below the ion energies required by earlier models. Recent work has provided a new outlook on how ion‐neutral collisions in the Jovian atmosphere are occurring, providing us with an entirely new set of impact cross sections. The model presented here simulates oxygen and sulfur precipitation, taking into account the new cross sections, every collision process, the measured ion fluxes above Jupiter's polar aurora, and synthetic X‐ray spectra. We predict X‐ray fluxes, efficiencies, and spectra for various initial ion energies considering opacity effects from two different atmospheres. We demonstrate that an in situ measured heavy ion flux above Jupiter's polar cap is capable of producing over 1 GW of X‐ray emission when some assumptions are made. Comparison of our approximated synthetic X‐ray spectrum produced from in situ particle data with a simultaneous X‐ray spectrum observed by XMM‐Newton shows good agreement for the oxygen part of the spectrum but not for the sulfur part

Magnetosphere-Ionosphere Coupling at Jupiter and Saturn: Evidence from X-Ray Emission

Auroral particle precipitation dominates the chemical and physical environment of the upper atmospheres and ionospheres of the outer planets. Precipitation of energetic electrons from the middle magnetosphere is responsible for the main auroral oval at Jupiter, but both energetic electron and ion precipitation take place in the polar caps. Most focus at both Earth and Jupiter has been on electron precipitation and the associated upward field-aligned current regions. However, x-ray emission that is observed from Jupiter’s polar regions appears to be due to the precipitation of energetic heavy ions coming from the outer magnetosphere and magnetopause. Bunce et al. have suggested that magnetic reconnection at the dayside magnetopause is responsible for the downward currents. The ions must be accelerated to MeV energies in order for the sulfur and oxygen ions to lose most of their electrons during collisions with atmospheric molecular hydrogen. Charge exchange collisions follow the electron removal collisions and the product ions emit the observed x-rays. We have used a Monte Carlo code to study the ion precipitation process, including the altitude-dependence of the energy deposition and the x-ray production from charge-exchange collisions. We have also calculated the spectrum of the secondary electrons produced during this process as well as the fieldaligned currents. Escaping secondary electrons should be accelerated upward to MeV energies due to the same field-aligned potentials responsible for the downward ion acceleration. Evidence exists for relativistic electrons in the outer magnetosphere. An x-ray aurora has not been observed at Saturn, which is perhaps not surprising given that major differences exist in the two planets magnetosphere-ionosphere (MI) coupling. Ion precipitation processes, particularly those leading to x-ray emission at Jupiter, will be discussed during this talk, as well as the implications for MI coupling at the outer planets

The evaluation of renal allo and autotransplantation results in cats

WOS: 000180152200023For the first time in Turkey, renal autotransplantation in 7 cats and renal allotransplantation in 7 cats having blood-crossmatch-compatible donors were performed. Immunosuppression was maintained by a prednisolone-cyclosporin combination in the renal allotransplantation group. All cats in the renal allotransplantation group died during the operation or between 3 and 72 h postoperatively. Two cats in the renal autotransplantation group survived approximately 2 years. Hyperacute or acute rejection findings were not encountered according to perioperative observations, laboratory findings or histopathological evaluations of renal allografts. The results of histopathological evaluations of renal allografts indicated acute tubular necrosis (ATN) findings caused by renal hypoperfusion due to hypotension. The reason for ATN was considered to be a result of hypotension that invasive methods could not control

A Versatile Numerical Method for the Multi-Fluid Plasma Model in Partially- and Fully-Ionized Plasmas

© 2018 Institute of Physics Publishing. All rights reserved. We present an innovative numerical method that solves for the multi-fluid plasma equations, including the transport, frictional, and chemical reactions terms, coupled to full Maxwell's equations. The numerical method features a scheme for the electromagnetic field with a proper scaling for the numerical dissipation, a scheme that solves flows at all speeds regimes (from subsonic to supersonic), and implicit time integration to tackle the stiffness of the system. Verification of the numerical scheme is also presented in a wide variety of plasma conditions.status: publishe

A GPU-enabled implicit Finite Volume solver for the ideal two-fluid plasma model on unstructured grids

This paper describes the main features of a pioneering unsteady solver for simulating ideal two-fluid plasmas on unstructured grids, taking profit of GPGPU (General-purpose computing on graphics processing units). The code, which has been implemented within the open source COOLFluiD platform, is implicit, second-order in time and space, relying upon a Finite Volume method for the spatial discretization and a three-point backward Euler for the time integration. In particular, the convective fluxes are computed by a multi-fluid version of the AUSM+up scheme for the plasma equations, in combination with a modified Rusanov scheme with tunable dissipation for the Maxwell equations. Source terms are integrated with a one-point rule, using the cell-centered value. Some critical aspects of the porting to GPU’s are discussed, as well as the performance of two open source linear system solvers (i.e. PETSc, PARALUTION). The code design allows for computing both flux and source terms on the GPU along with their Jacobian, giving a noticeable decrease in the computational time in comparison with the original CPU-based solver. The code has been tested in a wide range of mesh sizes and in three di erent systems, each one with a di erent GPU. The increased performance (up to 14x) is demonstrated in two representative 2D benchmarks: propagation of circularly polarized waves and the more challenging Geospace Environmental Modeling (GEM) magnetic reconnection challenge.status: accepte