Inner-shell photodetachment of na-using r-matrix methods

Inner-shell photodetachment of Na-near the L-edge threshold was investigated using the R-matrix method. Significant structure was found in the cross section, and this structure is shown to be related to the complicated correlated electron dynamics endemic in negative ions. Comparison with experiment suggests that the absolute values of the measured cross section might be too small by a factor of two. © 2020 by the authors

Factors Associated with Revision Surgery after Internal Fixation of Hip Fractures

Background: Femoral neck fractures are associated with high rates of revision surgery after management with internal fixation. Using data from the Fixation using Alternative Implants for the Treatment of Hip fractures (FAITH) trial evaluating methods of internal fixation in patients with femoral neck fractures, we investigated associations between baseline and surgical factors and the need for revision surgery to promote healing, relieve pain, treat infection or improve function over 24 months postsurgery. Additionally, we investigated factors associated with (1) hardware removal and (2) implant exchange from cancellous screws (CS) or sliding hip screw (SHS) to total hip arthroplasty, hemiarthroplasty, or another internal fixation device. Methods: We identified 15 potential factors a priori that may be associated with revision surgery, 7 with hardware removal, and 14 with implant exchange. We used multivariable Cox proportional hazards analyses in our investigation. Results: Factors associated with increased risk of revision surgery included: female sex, [hazard ratio (HR) 1.79, 95% confidence interval (CI) 1.25-2.50; P = 0.001], higher body mass index (fo

Silicon ISM X-ray absorption: The gaseous component

We present a detailed analysis of the gaseous component of the Si K edge using high-resolution Chandra spectra of low-mass X-ray binaries. We fit the spectra with a modified version of the ISMabs model, including new photoabsorption cross-sections computed for all Si ionic species. We estimate column densities for Si I, Si II, Si III, Si XII, and Si XIII, which trace the warm, intermediate temperature, and hot phases of the Galactic interstellar medium. We find that the ionic fractions of the first two phases are similar. This may be due to the physical state of the plasma determined by the temperature or due to the presence of absorber material in the close vicinity of the sources. Our findings highlight the need for accurate modelling of the gaseous component before attempting to address the solid component. © 2020 Oxford University Press. All rights reserved

Time-Dependent Approach to Atomic Autoionization

A time-dependent approach to the study of atomic autoionization in two-electron systems is formulated. In the first step a two-dimensional (2D) model He atom is constructed by replacing the full 3D electrostatic interaction with a 1D soft-core interaction. The autoionization decay of doubly excited states constructed within the model is calculated by both standard perturbation theory and direct solution of the time-dependent Schrödinger equation. Configuration-interaction theory is invoked to obtain correlated resonance states, and strong laser fields are found to alter the decay rates. In the second step the full 6D wave function for the He atom is expanded in coupled spherical harmonics using a procedure as described by C. Bottcher, D. R. Schultz, and D. H. Madison [Phys. Rev. A 49, 1714 (1994)]. Solution of the time-dependent Schrödinger equation reduces to solving the propagator equations for the 3D expansion coefficients on a B-spline collocation lattice. Autoionizing decay rate calculations using product resonance states are found to be in qualitative agreement with the 2D model results

Fracture fixation in the operative management of hip fractures (FAITH): an international, multicentre, randomised controlled trial

Background Reoperation rates are high after surgery for hip fractures. We investigated the effect of a sliding hip screw versus cancellous screws on the risk of reoperation and other key outcomes. Methods For this international, multicentre, allocation concealed randomised controlled trial, we enrolled patients aged 50 years or older with a low-energy hip fracture requiring fracture fixation from 81 clinical centres in eight countries. Patients were assigned by minimisation with a centralised computer system to receive a single large-diameter screw with a side-plate (sliding hip screw) or the present standard of care, multiple small-diameter cancellous screws. Surgeons and patients were not blinded but the data analyst, while doing the analyses, remained blinded to treatment groups. The primary outcome was hip reoperation within 24 months after initial surgery to promote fracture healing, relieve pain, treat infection, or improve function. Analyses followed the intention-to-treat principle. This study was registered with ClinicalTrials.gov, number NCT00761813. Findings Between Mar