My research has focused mostly on "completely integrable" infinite dimensional Hamiltonian systems, like the KdV equation, the nonlinear Schrödinger equation and the Toda lattice. I have been particularly interested in asymptotic problems like the investigation of long time asymptotics, semiclassical asymptotics, zero dispersion limits and continuum limits of solutions of initial and initial-boundary value problems for nonlinear dispersive partial differential equations and nonlinear lattices, including difficult problems involving instabilities (like the so-called modulational instability). I have used and extended techniques from PDE theory, complex analysis, harmonic analysis, potential theory and algebraic geometry. Along the way, I have made contributions to the analysis of Riemann-Hilbert factorisation problems on the complex plane or a hyperelliptic Riemann surface and the theory of variational problems for Green potentials with harmonic external fields. In a sense I have worked on a "nonlinear microlocal analysis" that generalises the classical theory of stationary phase and steepest descent.