Séminaire de l'INPHYNI: Swen Helstroffer --- Andreas Zmija

Stellar Intensity Interferometry - Photon Correlations in Astrophysics (A. Zmija)

Abstract:
Stellar intensity interferometry is the analysis of arrival times of photons from astrophysical sources. Using either one or multiple telescopes simultaneously, it can serve a multitude of different purposes. While it was established in high-angular resolution astronomy within the last decade, a recent idea in the context of the IC4Stars project is to use it as a tool to verify the nature of very narrow emission lines of certain stellar objects, which are suspected to originate in stimulated emission. In this presentation I will give an overview of both science cases in the context of my work in this field.


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How Plant Pathogens Find Roots: Swimming Through Biomimetic Gradients (S. Helstroffer)

Abstract:
Plant pathogens from the genus Phytophthora are responsible for major crop diseases worldwide. Their infection cycle involves motile zoospores: biflagellated microscopic cells that swim through the rhizosphere to locate and infect plant roots. While biological studies have identified several chemical cues involved in this process, the physical mechanisms by which these swimmers navigate complex chemical environments remain poorly understood.
In this seminar, I will present my postdoctoral work at INPHYNI on the chemotactic behavior of Phytophthora zoospores. In a microfluidic device, we reproduce pH gradients similar to those found near growing roots and follow the trajectories of individual zoospores as they swim through these gradients. By linking swimming behavior to the local chemical gradient and combining experiments with simulations, we can understand how changes in orientation and motility give rise to accumulation. This provides a new way to understand how plant pathogens explore their environment and find their hosts.