Tune shift with amplitude of the system. When the tune reaches resonant values, it can be unstable, and thus a tune-shift with amplitude can limit the stability region, or dynamic aperture. In classical mechanics, a simple example of a system with tune shift with amplitude is a pendulum. In accelerator physics, both the transverse and the longitudinal dynamics show tune shift with amplitude. A simple model of the transverse dynamics is of an oscillator with a single sextupole, it is referred to as the Hénon map. Another model for this case is the Standard Map. An important example is the typical case of distributed
Some Girls Are Bigger Than Others performed live only once: at the final concert by the Smiths, at Brixton Academy, London, on 12 December 1986. The performance, which included a verse ("On the shop floor, there's a calendar, as obvious as snow, as if we didn't know") not used in the studio version, was recorded and later featured as a B-side on the 12" and cassette edition of the "I Started Something I Couldn't Finish" single in November 1987. Amateur footage of the entire concert has since appeared online. In Germany, "Some Girls Are Bigger Than Others" was released as a single in slightly edited form,