Articles are presented covering a wide range of topics in the mathematical methods of quantum physics. These include infinite dimensional analysis based on white noise operator algebra methods Feynman path integrals quantum mechanics on non-simply connected spaces recent results in supersymmetric theories stochastic and quantum dynamics Yang-Baxter systems statistical physics thermo field dynamics and quantum field theory.The essays are based on lectures contributed for the Second Jagna International Workshop held in honour of Prof. Hiroshi Ezawa a distinguished physicist educator and former president of the Physical Society of Japan.