Ion energy measurements were taken simultaneously using one retarding field energy analyzer placed at the open end of the plasma source, and one in the plasma diffusion region of an expanding low pressure argon plasma. An electric double layer was found, which is well separated from the region of high magnetic field and which is downstream of the maximum in the magnetic field gradient. An axially movable analyzer was used to determine the position of the double layer. It appears to be more closely connected to the rapid change in diameter from the source to the diffusion chamber, but still has a radial dimension close to that of the source diameter. These results suggest that the double layer forms, not as much as a result of a magnetic nozzle, but rather as a reaction to a dramatic change in boundary conditions. Still, a magnetic field of at least a few tens of Gauss in the double layer region is necessary for its spontaneous formation.

The Njord device was constructed with the aim of investigating instabilities and turbulence in plasmas with flows and beams, which are common also in space plasmas. Njord is an inductively coupled helicon plasma device with 13.56 MHz RF power inserted into the working gas by means of a saddle antenna through a 13.8 cm inner diameter Pyrex tube. The source plasma expands through a 7 cm long and 20 cm wide port into a 0.6 m diameter and 1.2 m long chamber. Two magnetic field coils around the source and one additional downstream coil produce a magnetic field of about 25 mT at maximum. We have characterized current-free double layers in argon plasmas, and we find that they are generated at the position where the plasma expands into the main chamber. Further, the effect of shaping the magnetic field from an expanding one to a mirror shaped field by means of the downstream coil has been investigated. The downstream density and the plasma potential increase significantly when all the magnetic field lines in the source are passing also through the port-dome intersection without intersecting the port walls. The ion beam disappears when the plasma potential increases up to a potential similar to that in the source.

Aims The aim of this study was to describe variation in hip fracture treatment in Norway expressed as adherence to international and national evidence-based treatment guidelines, to study factors influencing deviation from guidelines, and to analyze consequences of non-adherence. Methods International and national guidelines were identified and treatment recommendations extracted. All 43 hospitals routinely treating hip fractures in Norway were characterized. From the Norwegian Hip Fracture Register (NHFR), hip fracture patients aged > 65 years and operated in the period January 2014 to December 2018 for fractures with conclusive treatment guidelines were included (n = 29,613: femoral neck fractures (n = 21,325), stable trochanteric fractures (n = 5,546), inter- and subtrochanteric fractures (n = 2,742)). Adherence to treatment recommendations and a composite indicator of best practice were analyzed. Patient survival and reoperations were evaluated for each recommendation. Results Median age of the patients was 84 (IQR 77 to 89) years and 69% (20,427/29,613) were women. Overall, 79% (23,390/29,613) were treated within 48 hours, and 80% (23,635/29,613) by a surgeon with more than three years’ experience. Adherence to guidelines varied substantially but was markedly better in 2018 than in 2014. Having a dedicated hip fracture unit (OR 1.06, 95%CI 1.01 to 1.11) and a hospital hip fracture programme (OR 1.16, 95% CI 1.06 to 1.27) increased the probability of treatment according to best practice. Surgery after 48 hours increased one-year mortality significantly (OR 1.13, 95% CI 1.05 to 1.22; p = 0.001). Alternative treatment to arthroplasty for displaced femoral neck fractures (FNFs) increased mortality after 30 days (OR 1.29, 95% CI 1.03 to 1.62)) and one year (OR 1.45, 95% CI 1.22 to 1.72), and also increased the number of reoperations (OR 4.61, 95% CI 3.73 to 5.71). An uncemented stem increased the risk of reoperation significantly (OR 1.23, 95% CI 1.02 to 1.48; p = 0.030). Conclusion Our study demonstrates a substantial variation between hospitals in adherence to evidence-based guidelines for treatment of hip fractures in Norway. Non-adherence can be ascribed to in-hospital factors. Poor adherence has significant negative consequences for patients in the form of increased mortality rates at 30 and 365 days post-treatment and in reoperation rates. Cite this article: Bone Joint Open 2020;1-10:644–653.

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We have studied the behavior of Fe ions in the slow solar wind, using a fluid model extending from the chromosphere to 1 AU. Emphasis is on elemental "pileup" in the corona, i.e., a region where the Fe density increases and has a local maximum. We study the behavior of individual Fe ions relative to each other in the pileup region, where Fe +10 and Fe +12 have been used as examples. We find that elemental pileups can occur for a variety of densities and temperatures in the corona. We also calculate the ion fractions and obtain estimates for the freezing-in distance of Fe in the slow solar wind. We find that the freezing-in distance for iron is high, between 3 and 11 R , and that a high outflow velocity, of order 50-100 km s-1 , in the region above the temperature maximum is needed to obtain ion fractions for Fe +10 and Fe +12 that are consistent with observations.