Diffusion is the random movement of molecules from one region to another. It is important in many fields such as materials science and life science, for example when a drug is released in a body, or when proteins in a cell interacts with binding sites. Statistics is needed to quantify the information contained in microscopy images, and a well-known method is single particle tracking. This means that particles are identified and followed in consecutive frames of a video to measure their diffusive mobility.
More precise results with new method
The thesis describes a promising method that has been developed for single particle tracking, where it is possible to analyse mixtures of particles that have different diffusion coefficients. Thus, the estimation of diffusion in complex systems has been improved, so that the results when performing experiments will be more accurate. The codes and programmes for the method are shared, and Marco has also developed a graphical user interface which is freely available to download.
The project has been interdisciplinary, and Marco has been responsible for the statistics part, while research institutes in Sweden and Belgium have been responsible for the more experimental parts. With that said, Marco feels that he has learnt a lot about microscopy during these five years.
Study exchange led to PhD position
When Marco was studying at master level in Italy he had the possibility to do an exchange for six months. He wanted to try a Nordic country, and Gothenburg seemed to be the best option. His supervisor during this time was Sergei Zuyev and he encouraged Marco to apply for an announced PhD position. Since Marco wanted to go more into applications, this project with real world data was just what he wanted.
– I have really had a good time here and Gothenburg is a nice city, even if the weather is not what I am used to. I have made many friends and my colleagues are open to discuss with, it is a very collaborative work environment. If I would stay on in the academic world, it would be in Sweden.
But instead, Marco is heading for Amsterdam where he will begin at a bank in September. He will work with quantitative analyses such as probability predicting and risk modelling. The field of applications where statistical methods can be used is broad!
Marco Longfils will defend his PhD thesis “Quantitative methods for diffusion measurements in fluorescence microscopy” on May 29 at 10.15 in the room Pascal, Hörsalsvägen 1. Supervisor is Aila Särkkä.
Text and photo: Setta Aspström
Picture: Visualization of a sequence of ten consecutive frames of a single particle tracking simulation of diffusing particles, Marco Longfils