Spectra of Tukey types of ultrafilters on Boolean algebras
  Extending recent investigations on the structure of Tukey types of ultrafilters on $\mathcal{P}(\omega)$ to Boolean algebras in general, we classify the spectra of Tukey types of ultrafilters for several classes of Boolean algebras, including interval algebras, tree algebras, and pseudo-tree algebras. 
Jennifer A. Brown and Natasha Dobrinen
math.LO