This book is devoted to the development and application of the quasiparticle approach in the modern theory of solids in order to present some new results, ideas and phenomena. Considerable attention is paid to defects in quantum crystals.The volume, presenting a detailed discussion of quasiparticle mechanics and kinetics in nonstationary deformed solids, would be of particular interest to a wide class of specialists, lecturers and students in physics and mathematics.Contents:Energy Spectrum of Defectons in Quantum CrystalsDefecton Statistics and ThermodynamicsKinetics of a Defecton GasStructure of a Quantum Crystal with Delocalized DefectsDynamics Theory of Deformable Crystal with Quasiparticle ExcitationsNonlinear Excitations in Deformable SolidsReadership: Condensed matter physicists and applied mathematicians.Key Features:Addresses safety assessment issues for subsurface disposal of nuclear waste — important worldwide and currently highly topical in the UKReports a uniquely comprehensive set of experimental results related to the movement of radionuclides in the near-surface environment — with web-based data accessPresents state-of-the-art modeling tools for contaminant transport in vegetated soils