Visiting researchers & seminars

Julien Arino

• Title:
  A model with multiple pathogens infecting multiple species
• Abstract:
  The Mackenzie River is a large river in northern Canada flowing over 1,700 kilometers entirely within the Northwest Territories from Great Slave Lake to the Beaufort Sea. The drainage basin covers almost 2 million square kilometers. As a northern ecosystem, the Mackenzie system is experiencing the consequences of climate change more acutely than ecosystems in more temperate regions. For instance, the ranges of some species there are undergoing fundamental modifications that are observable over small time periods. In recent years, more and more salmons are being observed in the Mackenzie river system, with both Pacific and Atlantic stock having been observed in the Mackenzie. Resident species such as arctic char or dolly varden typically migrate to open waters during summer to feed, but never stray very far from the river and return to the river or lakes to overwinter. By comparison, salmon spend most of their lives at sea far from the rivers in which they are born. This means that there is a risk that salmon will introduce into the ecosystem novel viruses that they have acquired in distant ecosystems.
  This motivates the model that I will present here, which considers the spread of V pathogens among P populations. We take a simple SLIR model and further assume that co-infection cannot happen, so that once infected, an individual cannot become infected by another pathogen. This results in a large system of 2P(V+1) equations. After some considerations on this general system, we consider the equivalent continuous time Markov chain and use a multitype branching process approximation to develop a better understanding of the behaviour of the system at the start of spread. We illustrate with a few special cases.
  This is joint work with Clotilde Djuikem.
• Affiliation:
  Department of Mathematics, University of Manitoba (Canada)
• Seminar details:
  Lagrange Gris room in Lagrange building, Inria Centre at Université Côte d’Azur
• Organizer(s):
  Frédéric Grognard & Ludovic Mailleret, Team MacBes (Inria)

Franck Ruffier

• Title:
  Early vision for robotics
• Abstract:
  The talk will present bio-inspired vision systems for robotics, particularly utilizing early vision, such as optic flow, for aerial navigation (Serres & Ruffier 2017). For instance, we show recently that visual models enable robots to assess and control attitude without accelerometer, explaining some insect flight capabilities (de Croon et al. 2022). Moreover, collective motion models solely based on early vision demonstrated how spherical robots can achieve swarming and milling behaviors using panoramic visual information (Castro, Ruffier & Eloy 2024, Castro, Eloy & Ruffier 2024).
• Affiliation:
  SBI-Biorobotics research group at Institut des Sciences du Mouvement (ISM), a joint research unit with AMU
• Seminar details:
  Coriolis room in Galois building, Inria Centre at Université Côte d’Azur
  Hybrid mode on zoom (join)
• Organizer(s):
  Christophe Henry, Team Calisto (Inria)

Laura Caravenna

• Title:
  Consensus in Multiagent Systems with Lack of Connection
• Abstract:
  We consider a system of N agents in Rd, indexed by j, that interact with a cooperative rule. The influence of agent k on agent j is given by time-dependent functions that do not depend on the state: the function u_{jk} : [0, +∞) → [0, +∞) that we assume to be locally integrable. We discuss conditions that guarantee that a given system, mathematically satisfying the ODEsx’j = \sum{k=1}^N u_{jk}(t) (x_k − x_j),converges to consensus for any initial configuration of {x1, …, xN}, where by consensus we mean that there exists a common limit value x* of all the agents’ trajectories x_j(t).
  This is a joint work with Bentaibi (Padova), Gauthier (Toulon), Rossi (IUAV).
• Affiliation:
  Department of Mathematics, University of Padova (Italy)
• Seminar details:
  Coriolis room in Galois building, Inria Centre at Université Côte d’Azur
• Organizer(s):
• Paola Goatin, Team Acumes (Inria)