Interbranch transient beating of X-ray intensities in deformed crystals.
X-ray dynamical diffraction in a deformed crystal is studied using the interbranch resonance concept. It is shown that appreciable beating of the X-ray intensities may be induced by a lattice distortion that produces interbranch transformations of the local dispersion surface. In X-ray plane-wave topography, this effect may be observed as interference fringes arising around the kinematical image of a defect. It is predicted that such interbranch fringes can be induced by edge dislocations.
On the widths of dislocation images in X-ray topography under low-absorption conditions
Detailed measurements have been made of dislocation image widths in X-ray topographs taken under conditions of low absorption (product of linear absorption coefficient and crystal thickness, μt = 0.15) with a silicon specimen and Mo Kα radiation. These have been compared with two theoretical models, the `diffracting-zone' model involving computation of misorientation gradient contours, and the direct-image `mosaic' model using calculations of effective misorientation contours. Neither model completely explains the image widths. The diffracting-zone model, though theoretically more attractive, gives a very poor correlation, probably because of (a) severe photographic limitations and (b) the uncertainty in the reconstruction of the intermediary image in translation topographs. For a given reflection the direct-image mosaic model gives a reasonably good prediction of image widths measured at half peak height. However, the widths in different reflections are not self-consistent; in particular, images in lower-order reflections are significantly wider than those predicted by the model. This implies that contributions from interbranch scattering (giving an intermediary image component) are more important in lower-order reflections, and that such contributions are proportional to the widths obtained from misorientation (rather than misorientation gradient) contours.
Protecting Marine Biodiversity on the Continental Shelf Beyond 200 Nautical Miles
States are expending significant effort to chart the extent of their continental shelves where these extend beyond 200 nautical miles. As more is understood about marine biodiversity on the outer continental shelf, states may wish to regulate the use of biodiversity for the purposes of conservation or for future exploitation. This article identifies potential threats to marine biodiversity on the continental shelf, explores whether conservation is a legitimate purpose for exercising coastal state rights over the outer continental shelf under the Law of the Sea Convention, and considers the various legal rules that coastal states may use to protect marine biodiversity. The article concludes that the continental shelf regime is undesirably vague in some instances but that coastal states have a legal basis for taking action to regulate activities that impact the marine biodiversity of the outer continental shelf.