Atoms of a (regular) language L were introduced by Brzozowski and Tamm in 2011 as intersections of complemented and uncomplemented quotients of L. They derived tight upper bounds on the complexity of atoms in 2013. In 2014, Brzozowski and Davies characterized the regular languages meeting these bounds. To achieve these results, they used the so-called “átomaton” of a language, introduced by Brz...

Copper in biological systems presents a formidable problem: it is essential for life, yet highly reactive and a potential source of cell damage. Tight control of copper is thus a cellular necessity. To meet this challenge, cells have evolved pumps for transmembranous transport, chaperones for intracellular routing, oxidases and reductases to change the oxidation state of copper, and regulators ...