This project is centered around computations of two important invariants for algebraic and homotopy rings,namely,the algebraic K-theory and the topological cyclic homology groups associated to these rings. A general scheme for computations of topological cyclic homology groups was established in our thesis, and it is based on a descent theorem for the action of cyclic groups on the topological Hochschild homology spaces of certain rings. Using this scheme,computations of topological cyclic homology (and algebraic K-theory) groups were carried out for the rings of p-adic integers. One of the objectives of this project is to extend these computations to other rings, e.g. truncated polynomial rings over the rings of p-adic integers. A second objective is to study the descent problem in general for actions of profinite groups on spaces, and especially the particular case of the action of the Galois group of a fied extension KCL on the K-theory space of the field L.