Dynamic X-ray diffraction observation of shocked solid iron up to 170 GPa

Iron is the main constituent of the core of rocky planets; therefore, understanding its phase diagram under extreme conditions is fundamental to model the planets’ evolution. Using dynamic compression by laser-driven shocks, pressure and temperature conditions close to what is found in these cores can be reached. However, it remains unclear whether phase boundaries determined at nanosecond timescales agree with static compression. Here we observed the presence of solid hexagonal close-packed iron at 170 GPa and 4,150 K, in a part of the iron phase diagram, where either a different solid structure or liquid iron has been proposed. This X-ray diffraction experiment confirms that laser compression is suitable for studying iron at conditions of deep planetary interiors difficult to achieve with static compression techniques.

Liberty and individuality: the colony asylum in Scotland and England

This paper analyses the buildings, spaces and interiors of Bangour Village public asylum for the insane, near Edinburgh, and compares these with an English asylum, Whalley, near Preston, of similar early-twentieth-century date. The village asylum, which developed from a European tradition of rendering the poor productive through ‘colonisation’, was more enthusiastically and completely adopted in Scotland than in England, perhaps due to differences in asylum culture within the two jurisdictions. ‘Liberty’ and ‘individuality’, in particular, were highly valued within Scottish asylum discourses, arguably shaping material provision for the insane poor from the scale of the buildings to the quality of the furnishings. The English example shows, by contrast, a greater concern with security and hygiene. These two differing interpretations show a degree of flexibility within the internationalized asylum model which is seldom recognized in the literature.