MAGNETIC ORIENTATION OF AMPHIBOLE FIBRES
Amphibole fibres have been exposed to a unitbrm magnetic field while suspended in a dilute solution of celloidin in amyl acetate. The solvent was allowed to evaporate while the field was maintained so as to obtain a coherent film of magnetically oriented fibres bonded together by celloidin. X-ray-diffraction patterns were then recorded in transmission geometry, and the orientation of the fibrils around their fibre axis was determined. The fibres are oriented in azimuth as well as lengthwise, though those that align normal to the field show a much more restricted range of azimuthal orientations than those that align parallel to the field. Crystallographic control of the principal maguetic axes is discussed; the orientation properties are not fully explained, but their attribution to magretite present in bulk samples is rejected.
Influence of metal cation order on magnetic order in manganogrunerite, (Fe,Mg,Mn)7Si8O22(OH)2, a quasi-one-dimensional chain antiferromagnet
Abstract The magnetic susceptibility of ordered and partially disordered manganogrunerites (composition Ca0.1Mn1.9Mg1.25Fe3.562+Fe0.383+Si7.81O22(OH)2 and Ca0.24Mn1.57Mg2.27Fe2.762+Fe0.323+Si7.84O22(OH)2) has been measured between room temperature and 5 K. The influence of disordering of metal cations over the M(1,2,3) sites of the octahedral ribbon in these amphiboles is to dilute Fe2+ within the ribbon. We observe a reduction in both θp and TN as a function of both increased Mg/(Mg+Fe) and metal cation disorder, linked to a reduction in the strength of magnetic coupling between and within the one-dimensional chains of the structure.
Teaching learning disability to undergraduate medical students
The education of doctors shapes their professional identity: who they are and how they practise. Where does the issue of learning disability fit in? What is it and of what factors should doctors in training be aware?

The training of medical students has been defined by the General Medical Council (