Journal of Statistical Physics, Vol. 115, Nos. 1/2, April 2004. p. 47-56.
A unified perspective is given on a number of different problems involving the coupling of a localized quantum spin degree of freedom to the low energy excitations of an antiferromagnet, a spin glass, or a Kondo insulator. The problems are related to those in the class often referred to as "Bose Kondo."