Are there particular diseases that present particular challenges or are there huge differences, big similarities? Do you want to tell us something about that?

I can put a number on it.

It was 16 years ago that I first worked on infectious diseases, over 16 years ago.

So that ages me.

I think if there wasn't an interesting breadth of mathematics, I probably would have gotten bored and wandered off to a different application.

That said, one of the papers that I worked on, I think it came out in 2014, but don't quote me on that, looking at how to embed how heterogeneity and how susceptible and how infectious you are as like in a population in an arbitrary distribution.

That work is something that I started working with a colleague somewhat recently on how it relates to gully modelling and erosion of gullies because the mathematics is similar in that we need an arbitrary distribution of soil density and size or soil size and or density we couldn't do both independently we're using the mathematics that we did so even now i sometimes go play with problems that have similar mathematics for different applications but as you've heard most of my work is same sort of application broadly speaking but infectious diseases are also very different so if you think about this you know some diseases are spread directly human to human through like the air respiratory diseases if you will somebody sneezes you breathe it in that type of thing like your colds and your flus and your covid some are spread more through things like mosquitoes so a mosquito bites an infected human After some time the mosquito's infectious bites a susceptible human, the human becomes infected.

Are you still encountering challenges or new...