This book provides a representative sampling of the latest advances in theoretical physics. Chapters 1 and 2 deal with the Hydrogen atom. In Chapter 1, Blaive and Cadilhac carry out an analysis of hydrogenoid atomic wave functions. In Chapter 2, Boudet, Blaive Geniyes and Vanel carry out a relativistic calculation with retardation of the photoelectric effect of Hydrogen. Chapters 3 and 4 look at atoms in the presence of an external radiation field. Chapter 3 by Dastidar and Dastidar examines above-threshold ionization of Argon in a laser field. In Chapter 4, Kazakov applies the Jaynes-Cummings model to an atom interacting simultaneously with a quasiresonant classical field and a quantized mode. Quantum dynamical problems are addressed in Chapters 5 and 6. In Chapter 5, Baute, Egusquiza and Muga study the effect of negative and classically-forbidden momenta in one-dimensional quantum scattering. Chapter 6 by Bellini finds analytical solutions to reaction-diffusion equations by mapping on a time-independent Schrödinger equation. Chapters 7 and 8 are devoted to nuclear and particle physics. In Chapter 7, Kravchenko and Soznik obtain the nucleon-nucleus optical potential in the nuclear matter approximationw with the generalized Skyrme interation. In Chapter 8, Terasaki examines non-factorizable contributions in decays. The final three chapters contain various mathematical studies which are of interest to theoretical physics in general. In Chapter 9, Shiqing analyzes the equations of motion for the Newtonian n-body problem. Riazi looks at the geometry and topology of solitons in Chapter 10, and the book concludes with Chapter 11 containing a study by Elipe of the rotations of perturbed triaxial rigid bodies.