Centre for Mathematical Biology, Oxford-Man Institute of Quantitative Finance, University of Oxford, Oxford OX1 3LB, UK. klingbeil@maths.ox.ac.uk|Centre for Mathematical Biology, Oxford-Man Institute of Quantitative Finance, University of Oxford, Oxford OX1 3LB, UK. klingbeil@maths.ox.ac.uk|Centre for Mathematical Biology, Oxford-Man Institute of Quantitative Finance, University of Oxford, Oxford OX1 3LB, UK. klingbeil@maths.ox.ac.uk|Centre for Mathematical Biology, Oxford-Man Institute of Quantitative Finance, University of Oxford, Oxford OX1 3LB, UK. klingbeil@maths.ox.ac.uk