Hanna Tuomisto, A diversity of beta diversities: straightening up a concept gone awry. Part 1. Defining beta diversity as a function of alpha and gamma diversity, Ecography, Vol. 33, No. 1 (FEBRUARY ...

It was accepted that beta cells could only function correctly in the presence of the other hormone-producing cells - alpha, delta and gamma cells - grouped together in islets within the pancreas.

Cell nucleus in white, beta cells and insulin in green, alpha cells (hormone glucagon) in red and delta cells (hormone somatostatin) in magenta. Credit: Helmholtz Zentrum München / Aimée ...

Brain state work can be couched in terms such as alpha, delta and so forth. However, this is actually referring to brain waves which specifically come from measuring brain activity using EEG.