The paper “Modulational instability and variational structure“, co-authored by Jared Bronski and Vera Hur, has been published in Studies in Applied Mathematics. The paper studies the modulational instability of periodic traveling waves for a class of Hamiltonian systems in one spatial dimension. The paper examines how the Jordan block structure bifurcates for small values of the Floquet exponent, and derives a stability criterion in terms of the kinetic and potential energies, the momentum, the mass of the underlying wave, and their derivatives. The results are illustrated by discussing analytically and numerically equations of Korteweg-de Vries type. A link to the paper is here.