The concept of reciprocal space is over 100 years old and has been of particular use for crystallographers to understand the patterns of spots seen on a detector when x-rays are diffracted by crystals. However, it has a much more general use, especially in the physics of the solid state. In order to understand what it is, how to construct it, and how to make use of it, it is first necessary to start with the so-called real or direct space and then show how reciprocal space is related to it. Direct space describes the objects we see around us, especially regarding crystals, their physical shapes and symmetries, and the arrangements of atoms within: the so-called crystal structure. eciprocal space, on the other hand, deals with the crystals as seen through their diffraction images. Indeed, crystallographers are accustomed to working backward from the diffraction images to the crystal structures, which we call crystal-structure solution. In solid-state physics, one usually works the other way, starting with reciprocal space to explain various solid-state properties, such as thermal and electrical phenomena. <...>

The POND Excel® spreadsheet allows determination and presentation of the attitudes of planes intersected in ‘oriented’ and ‘navigated’ diamond drillcore. Two drillcore navigation measurements (azimuth and plunge from a deviation log), and two plane-to-drillcore angular measurements (angle to core axis, and angle between orientation mark and intersection ellipse) are required to obtain a solution.

A distal fragment of a radius of Azhdarchidae indet. from Upper Campanian (Upper Cretaceous) marine deposits of Saratov is described. The bone belongs to a large pterosaur, of about 4.3 m wing span. It differs from the radii of Azhdarcho, Montanazhdarcho, and cf. Quetzalcoatlus in the asymmetrical distal epi-physis and, in addition, from Montanazhdarcho and cf. Quetzalcoatlus in the absence of a pneumatic foramen on the posterior side. In its geographical and stratigraphical positions, this specimen is close to the azhdarchid Bogolubovia orientalis (3–4 m in wing span), known from a fragmentary cervical vertebra from the Campanian of the Penza Region, and may belong to this species.