1. School of Mathematics, Statistics and Applied Mathematics, National University of Ireland Galway, University Road, Galway, Republic of Ireland
2. CNRS and Institut Jean le Rond d'Alembert, UMR 7190, Université Paris 6, 4 place Jussieu case 162, Paris 75005, France
3. MOX - Politecnico di Milano and Fondazione CEN, piazza Leonardo da Vinci 32, Milano 20133, Italy
4. School of Mechanical and Materials Engineering, University College Dublin, Belfield, Dublin 4, Republic of Ireland