Applied Maths Seminar 2026-2027

Organisers: Clarice Poon and Joe Webber

The Applied Maths Seminars are held on Fridays 12:00-13.00. The seminar is hybrid; you can attend in person in room B3.02 or on MS Teams. The Team for the seminar is the same as last year, but if you are not a member, you can send a membership request via MS Teams or email the organisers.

If attending in person, we usually head for lunch on campus as a group after the seminar finishes.

Please contact Clarice Poon or Joe Webber if you have any speaker suggestions for future terms.

Seminar Etiquette:

Here is a set of basic rules for the seminar:

Please keep your microphone muted throughout the talk. If you want to ask a question, please raise your hand and the seminar organiser will (a) ask you to unmute if you are attending remotely or (b) get the speaker's attention and invite you to ask your question if you are in the room.
If you are in the room with us, the room microphones capture anything you say very easily, and this is worth keeping in mind ☺️.
You can choose to keep your camera on or not. Colleagues in the room will be able to see the online audience.

Term 1

Week	Date	Speaker	Title
1	09 Oct	David Smith (Birmingham)	Reduced effort biological fluid mechanics (abstract)
2	16 Oct	Jörg Nick (Birmingham)	The modulated Fourier expansion for waves propagating through time-modulated media (abstract)
3	23 Oct	Erik Jansson (Cambridge)	Template deformation methods for reconstruction (abstract)
4	30 Oct	Sebastiano Cominelli (LMA Marseille)
5	06 Nov	Havva Yoldas (TU Delft)
6	13 Nov	Malena Sabaté Landman (Warwick)
7	20 Nov	Sam Lewin (UC Berkeley/Oxford)
8	27 Nov	Carlés Falco (Oxford)
9	04 Dec	Sven Wang (EPFL)
10	11 Dec	Mozhdeh Erfanian (Warwick)

Abstracts

09/10/26 - David Smith (Birmingham) - Reduced effort biological fluid mechanics

Fluid mechanics on microscopic scales is vital to life on Earth, with examples spanning swimming marine algae and bacteria that underpin ecosystems, cilia that orient embryo development and keep organs clean, and spermatozoa that are central to many forms of sexual reproduction. These systems can often be modelled via the Stokes flow equations, which are linear, but can be complex to solve due to the presence of irregular moving boundaries. Following an introduction to the fundamental physics of microscale propulsion, this talk will describe two areas of our research: (1) methods to solve the Stokes flow equations computationally, in particular the nearest-neighbour method of regularised stokeslets -- motivated by reduction in computational `effort' (by both the computer and the programmer!), (2) a specific physiological adaptation by which spermatozoa appear to be able to reduce the effort needed to propel themselves to the egg, which we will interpret via elastohydrodynamic computations.

16/10/26 - Jörg Nick (Birmingham) - The modulated Fourier expansion for waves propagating through time-modulated media

Controlling waves by actively changing the material parameters of a medium enables the development of new acoustic and electrical devices. Modulating the material breaks classical properties like reciprocity and the conservation of energy, which complicates the mathematical analysis. Without a limiting amplitude principle, time-harmonic formulations are generally inapplicable. The talk introduces an alternative tool for the time-modulated acoustic wave equation, that is based on a modulated Fourier expansion (MFE). The solution is characterized by multiple smoothly varying coefficient functions, which solve a coupled system of evolutionary partial differential equations with temporally constant coefficients. For small-amplitude fast-time modulations, this system of evolutionary partial differential equations possesses a unique smoothly varying solution, which characterizes the exact solution up to a small defect. Discretization of the derived coupled system yields integrators that are stable and accurate when larger time steps are used, compared to those schemes that are applied to the time-modulated acoustic wave equation directly. Numerical experiments illustrate the theoretical results and the use of the approach.

23/10/26 - Erik Jansson (Cambridge) - Template deformation methods for reconstruction

In difficult imaging regimes, incorporating prior information can drastically improve reconstructions. One approach is to require that the reconstruction is a deformation of some known prior object. In cryo-EM reconstruction of a known protein, for instance, it is reasonable to assume the reconstructed conformation is a modification of a deposited known one. In sparse limited-angle tomography, one can require that the reconstruction is a deformation of an earlier high-quality scan.

Mathematically this is a natural setting for shape analysis, where Lie groups act on shape spaces of deformable objects. Originally developed for registration, these tools can be adapted for inverse problems. In this talk I show how the same mathematical construction yields methods applicable in both cryo-EM and tomographic reconstruction. I also outline paths to bring these methods to real data, including learning-based deformation approaches.