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Mars lacks a global magnetic field and instead has a unique, ‘hybrid’ magnetosphere composed of crustal magnetic fields, which are stronger in the Southern hemisphere than the Northern hemisphere. These crustal fields are believed to drive a twist in the magnetotail at Mars. This is important because heavy ions escape from this induced magnetotail, which is a major source of atmospheric erosion. We present analysis of heavy ions produced in Mars’ upper atmosphere that are transported downtail along the twisted current sheet and observed by the Mars Atmosphere and Volatile EvolutioN (MAVEN) mission. We identified O+, O$_2\, ^+$, and CO$_2\, ^+$ being accelerated to different energies at a range of distances downtail and found that heavy ions in the 10–50 eV energy population have the highest flux. We present tail slices of ion fluxes for different interplanetary magnetic field (IMF) configurations based on the BY component of the IMF and find that the different configurations affect the degree of tail twist and the transport of heavy ions in the induced magnetotail lobes. We find that the total escape rate for O+, O$_2\, ^+$, and CO$_2\, ^+$ is 5.5e24 s-1, with 50% escaping between 2–200 eV.

We characterize the nature of magnetic structures in the foreshock region of Mars associated with discontinuities in the solar wind. The structures form at the upstream edge of moving foreshocks caused by slow rotations in the interplanetary magnetic field (IMF). The solar wind plasma density and the IMF strength noticeably decrease inside the structures' core, and a compressional shock layer is present at their sunward side, making them consistent with foreshock bubbles (FBs). Ion populations responsible for these structures include backstreaming ions that only appear within the moving foreshock, and accelerated reflected ions from the quasi-perpendicular bow shock. Both ion populations accumulate near the upstream edge of the moving foreshock which facilitates FB formation. Reflected ions with hybrid trajectories that straddle between the quasi-perpendicular and quasi-parallel bow shocks during slow IMF rotations contribute to formation of foreshock transients., Comment: Submitted to Geophysical Research Letters

44 hips operated for insertion of the Christiansen hemiprosthesis at the County hospital of Nordland from 1968 to 1976 were evaluated in 1986. Seven hips had been reoperated because of loosening or mechanical failure of the prosthesis. Another four prostheses were found to have loosened at the time of follow-up, bringing the total loosening frequency up to 25 percent, 26 patients reported no pain from the hip, 20 of these were still in normal activity with no restriction in walking as a consequence of the defect hip. All the prostheses had been inserted in a varus position. Acetabular protrusion was found in 14 cases, indicating that there are frictional forces working at the hip joint, also with the trunnion bearing system. The average time from operation to verified loosening was nine years. The trunnion bearing may thus have spared the hip joint from stress during the first years of use.