This is an announcement for the paper "Isomorphisms and strictly singular operators in mixed Tsirelson spaces" by Denka Kutzarova, Antonis Manoussakis, and Anna Pelczar-Barwacz. Abstract: We study the family of isomorphisms and strictly singular operators in mixed Tsirelson spaces and their modified versions setting. We show sequential minimality of modified mixed Tsirelson spaces $T_M[(\mc{S}_n,\theta_n)]$ satisfying some regularity conditions and present results on existence of strictly singular non-compact operators on subspaces of mixed Tsirelson spaces defined by the families $(\mc{A}_n)_n$ and $(\mc{S}_n)_n$. Archive classification: math.FA Remarks: 29 pages, no figures Submitted from: amanousakis@isc.tuc.gr The paper may be downloaded from the archive by web browser from URL http://front.math.ucdavis.edu/1107.2810 or http://arXiv.org/abs/1107.2810