1. High-resolution X-ray scattering
2. Observation of algebraic decay of positional order in a smectic liquid crystal
3. Today it is realized that this state of matter is quite common in condensed matter. See, for example, J. Als-Nielsen, inR⊘ntgen Centennial, pp. 580–601, Haase, Landwehr and Umbach, eds., World Scientific (1997)
4. We shall use the nomenclature of Q for the scattering vector, Qofor the reciprocal lattice point of smectic A layering, and q=Q-Qo. By the radial direction, we mean q parallel to Qo