Supersonic and diffusive radiation flow is an important test problem for the radiative transfer models used in radiationhydrodynamics computer codes owing to solutions being accessible via analytic and numeric methods. We present experimental results with which to compare these solutions by studying supersonic and diffusive flow in the laboratory. We present results of higher-accuracy experiments than previously possible studying radiation flow through up to 7 high-temperature mean free paths of low-density, chlorine-doped polystyrene foam and silicon dioxide aerogel contained by an Au tube. Measurements of the heat front position and absolute measurements of the x-ray emission arrival at the end of the tube are used to test numerical and analytical models. We find excellent absolute agreement with simulations provided that the opacity and equation of state are adjusted within expected uncertainties; analytical models provide a good phenomenological match to measurements but are not in quantitative agreement due to their limited scope.
Delay in diagnosis of slipped capital femoral epiphysis has important implications with regard to slip severity and long-term hip outcomes. The aims of this review were to identify the incidence of delayed diagnosis of slipped capital femoral epiphysis in the hospital to which the authors are affiliated, and the causes for such delays. A retrospective review was conducted of all patients admitted to the Women's and Children's Hospital in Adelaide between January 1997 and October 2004 with a diagnosis of slipped capital femoral epiphysis. The inpatient and outpatient medical records for each patient were analysed to clarify the history of presentation and identify those patients with a delayed diagnosis. All radiographs were reviewed and the severity of the slip graded according to Southwick's classification. One hundred and two patients were included in this review, of which 20 had a delayed diagnosis and 25 a late presentation. Of the 20 (19.6%) patients who had a delayed diagnosis in this series, a minimum of 2 weeks elapsed between presentation to a health professional and diagnosis of slipped capital femoral epiphysis. Eight patients had seen their local doctor but the diagnosis was not made. The remaining 12 patients with delayed diagnosis had not seen a medical practitioner and had self-referred to a chiropractor or a physiotherapist. All of these patients underwent hip manipulation prior to diagnosis. There was a significant relationship between delay in diagnosis and an increased slip severity, when compared with both the remainder of this series and the late presentation group. Knee or distal thigh pain in slipped capital femoral epiphysis remains the commonest pitfall in diagnosis for local doctors, as well as mild slips being missed on radiograms by inexperienced surgeons or radiologists. An increasing presentation of adolescents with this disorder to allied health professionals for initial management warrants a broader education strategy than has been previously advocated. Slipped capital femoral epiphysis remains an enigmatic disorder; consequently delayed diagnosis of this condition is not likely to disappear. Despite this, the medical community must strive toward early diagnosis through continued education and vigilance.
Under uniaxial high-stress shock compression it is believed that crystalline materials undergo complex, rapid, micro-structural changes to relieve the large applied shear stresses. Diagnosing the underlying mechanisms involved remains a significant challenge in the field of shock physics, and is critical for furthering our understanding of the fundamental lattice-level physics, and for the validation of multi-scale models of shock compression. Here we employ white-light X-ray Laue diffraction on a nanosecond timescale to make the first in situ observations of the stress relaxation mechanism in a laser-shocked crystal. The measurements were made on single-crystal copper, shocked along the [001] axis to peak stresses of order 50 GPa. The results demonstrate the presence of stress-dependent lattice rotations along specific crystallographic directions. The orientation of the rotations suggests that there is double slip on conjugate systems. In this model, the rotation magnitudes are consistent with defect densities of order 10 12 cm À 2 .
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