Seminários, para a disseminação informal de resultados de investigação, trabalho exploratório de equipas de investigação, actividades de difusão, etc., constituem a forma mais simples de encontros num centro de investigação de matemática.
O CAMGSD regista e publica o calendário dos seus seminários há bastante tempo, servindo páginas como esta não só como um método de anúncio dessas actividades mas também como um registo histórico.
Exclusion processes with non-reversible boundary dynamics are one-dimensional interacting particle systems evolving on a finite lattice. These systems arise from the superposition of two different types of dynamics. In the bulk, particles evolve according to the usual symmetric simple exclusion dynamics, that is, at most one particle is allowed per site and jumps occur through nearest-neighbor interactions. Near the boundary, within a window of fixed size $l\geq 1$, particles may be created or annihilated according to rates depending on the local configuration in a finite neighborhood of the boundary. This choice of boundary dynamics is non-conservative and is considered under very general rates, allowing, in particular, the simultaneous creation of more than one particle. This flexibility creates a crucial distinction between our model and the simplified version first introduced in 2011 to describe boundary current fluctuations, where a very specific choice of boundary rates was considered. In this sense, our model generalizes earlier works by capturing not only non-linear evolutions of the particle density, but also, and more importantly, the surprising emergence of multiple stationary solutions to the hydrodynamic equation describing the density profile. In this talk, we define the model, discuss its hydrodynamic limit, and analyze several properties of the stationary solutions of the associated hydrodynamic equation. This presentation is based on joint works with Claudio Landim and João Pedro Mangi.
Globally hyperbolic spacetimes with a timelike boundary model spacetimes with naked singularities distributed on a timelike hypersurface, potentially admitting conditions on both the boundary and a Cauchy hypersurface. Typically, the boundary can serve as: (1) a cut-off for the system under consideration, or (2) a conformal completion of the spacetime, as in the case of asymptotically Anti-de Sitter spacetimes. First, we will review some of their general properties, including those related to causality, the existence of global orthogonal splittings, and the relationship between the properties of the boundary and the interior of the spacetime. Then, we will focus on the null-convexity of the boundary. This is a natural assumption satisfied by asymptotically AdS spacetimes, which implies that the interior of the spacetime retains most of the geometric properties of the boundaryless case, such as being causally simple with a Hausdorff space of lightlike geodesics. Based on joint work with L. Aké and JL. Flores (arxiv: 1808.04412) and with J. Herrera (arxiv: 2506.09032).
