26 04 im alumniV8
22 11 im fatiado face
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22 11 im fatiado youtube
22 11 im fatiado gmail
22 11 im fatiado brazil
22 11 im fatiado england
22 11 im fatiado spain

04 08 IM Noticia sitepercolationTítulo: Generalised oriented site percolation

Palestrante: Réka Szabó (Université Paris Dauphine)
Data: 09/08/2021
Horário: 15:00h
Local: Transmissão online.

Confira AQUI o link para transmissão.

Resumo: We consider a generalised oriented site percolation model on Z^d with arbitrary neighbourhood. The key additional difficulties as compared to standard oriented percolation are the lack of symmetry and, in two dimensions, of planarity. We establish that, despite these deficiencies, in the supercritical regime GOSP behaves qualitatively like OP. Joint work with Ivailo Hartarsky. All the talks are held in English.

The videos of the online seminars are available:
2020
2021-1

For the second semester, a few days after each meeting the video should be available at HERE

29 06 im noticia Seminário Brasileiro de ProbabilidadeTítulo: Discrete-time evolution in recombination

Palestrante: Servet Martínez, Universidad de Chile
Data: 30/06/2021
Horário: 13:00h
Local: Transmissão online.

Confira AQUI o link para transmissão. 
ID da reunião: 958 0581 3232

Resumo: We study the discrete-time evolution of a recombination transformation in population genetics acting on the set of measures on genetic sequences. The evolution can be described by a Markov chain on the set of partitions that converges to the finest partition. We describe the geometric decay rate to the limit and the quasi-stationary behavior when conditioned that the chain has not hit the limit.

22 06 im noticia Failure of the OrnsteinTítulo: Failure of the Ornstein--Zernike asymptotics for the pair correlation function at high temperature and small density

Palestrante: Yvan Velenik, Université de Genève
Data: 23/06/2021
Horário: 13:00h
Local: Transmissão online.

Confira AQUI o link para transmissão. 
ID da reunião: 958 0581 3232

Resumo: After briefly reviewing what is known about the long-distance asymptotic behavior of the 2-point function in lattice spin systems with finite-range interactions, I'll turn to the corresponding result for systems with interactions of infinite range. I'll show that, contrarily to standard expectations in Physics, the classical Ornstein-Zernike asymptotic formula for the 2-point function does not always hold, even in regimes where it was expected to, namely systems with interactions decaying exponentially fast at very high temperature and/or very low density. I'll explain how this is intimately related to the possible non analytic dependence of the correlation length in the relevant parameters (for instance, temperature), a phenomenon that can occur even in one-dimensional systems. This can be also related to a condensation transition in the graphical representations of these correlations. For simplicity, the focus will be on the Ising model, but most of the results hold much more generally. This is based on joint work with Yacine Aoun, Dmitry Ioffe and Sébastien Ott.

22 06 im noticia Long range Ising modelTítulo: Long-range Ising model and decaying fields- a contour approach

Palestrante: Lucas Affonso (IME-USP)
Data: 28/06/2021
Horário: 15:00h
Local: Transmissão online.

Confira AQUI o link para transmissão. 

Resumo: In 1982, Fröhlich and Spencer solved a long-standing conjecture about phase transition in a one-dimensional long-range Ising model for 1/r^2 interaction energy. After that, Cassandro, Ferrari, Merola, and Presutti extended the contour argument for other decays \alpha. In this talk, we address the multidimensional long-range Ising model, showing that a contour argument holds for all decays \alpha> d. As an application, we will show how our techniques can be used to study phase transition when the model has a decaying magnetic field.

The talk is based on joint work with Rodrigo Bissacot, Eric O. Endo, and Satoshi Handa.

All the talks are held in English.

The videos of the online seminars held in 2020 are available at HERE

For the 2021 series, a few days after each meeting the video should be available at HERE

15 06 im noticia The Ant Random WalkTítulo: The Ant Random Walk

Palestrante: Guilherme Reis (UFBA)
Data: 21/06/2021
Horário: 15:00h
Local: Transmissão online.

Confira AQUI o link para transmissão.

Resumo: The Ant RW belongs to the class of random walks with reinforcement. Our goal is to observe through this stochastic process the ant mill phenomenon: the walker is eventually trapped in a circuit of the graph which will be followed forever. In recent work we show that this phenomenon can be observed with weaker assumptions in the reinforcement function. Ours inspiration is the ant mill phenomenon in which a group of army ants are separated from the main group, lose the pheromone track and begin to follow one another, forming a continuously rotating circle. The ants are not able to go back home and will eventually die of exhaustion as we can see in the video "Why army ants get trapped in ‘death circles’" on YouTube.

Works in collaboration with Dirk Erhard and Tertuliano Franco.

All the talks are held in English.

The videos of the online seminars held in 2020 are available at HERE.

For the 2021 series, a few days after each meeting the video should be available at HERE.

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