Preface Mohamed Ben Ayed, Mohamed Ali Jendoubi, Yomna Rebai, Hassna Riahi and Hatem Zaag; Abbas Bahri: a dedicated life Mohamed Ben Ayed; 1. Blow-up rate for a semilinear wave equation with exponential nonlinearity in one space dimension Asma Azaiez, Nader Masmoudi and Hatem Zaag; 2. On the role of anisotropy in the weak stability of the Navier–Stokes system Hajer Bahouri, Jean-Yves Chemin and Isabelle Gallagher; 3. The motion law of fronts for scalar reaction-diffusion equations with multiple wells: the degenerate case Fabrice Bethuel and Didier Smets; 4. Finite-time blowup for some nonlinear complex Ginzburg–Landau equations Thierry Cazenave and Seifeddine Snoussi; 5. Asymptotic analysis for the Lane–Emden problem in dimension two Francesca de Marchis, Isabella Ianni and Filomena Pacella; 6. A data assimilation algorithm: the paradigm of the 3D Leray-α model of turbulence Aseel Farhat, Evelyn Lunasin and Edriss S. Titi; 7. Critical points at infinity methods in CR geometry Najoua Gamara; 8. Some simple problems for the next generations Alain Haraux; 9. Clustering phenomena for linear perturbation of the Yamabe equation Angela Pistoia and Giusi Vaira; 10. Towards better mathematical models for physics Luc Tartar.