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IM Seminar NoticiaTitle: One dimensional contact process with modified border conditions.
Speaker: Enrique D. Andjel.
Date: 02/10/2023
Horário: 3:30 p.m. to 4:30 p.m (Rio de Janeiro local time).
Local: C116 - Bloco C - CT – Instituto de Matemática – UFRJ. There will be no transmission online.

Abstract: In this joint work with Leonardo Rolla we study a one-dimensional contact process with two infection parameters. One of these parameters gives the infection rates at the boundaries of a finite infected region and the other one gives the rates within that region. We prove that the critical value of each of these parameters is a strictly monotone continuous function of the other parameter. We also show that if one of these parameters is equal to the critical value of the standard contact process and the other parameter is strictly larger, then the infection starting from a single point has a positive probability of surviving.


More complete information about the seminars can be found at HERE

Sincerely,
Organizers: Giulio Iacobelli e Maria Eulalia Vares.

IM Stochastic Adding Machines Noticia1Title: Stochastic Adding Machines
Speaker: Ali Messaoudi (Unesp, São José do Rio Preto)
Date: 25/09/2023
Horário: 3:30 p.m. to 4:30 p.m.
Local: C116 - Bloco C - CT – Instituto de Matemática – UFRJ. There will be no transmission online.

Abstract: A stochastic adding machine (defined in [PR Killeen and T. J. S. Taylor, Nonlinearity 13 (2000), no. 6, 1889–1903]) is a Markov chain whose states are natural integers, which models the process of adding the number $1$ but where there is a probability of failure in which a carry is not performed when necessary.
In this lecture, we will talk about probabilistic properties of extensions for the stochastic adding machine and their connections with other areas of mathematics such as Complex Dynamics and Linear Dynamics.
This is a joint work with Danilo Caprio and Glauco Valle.

More complete information about the seminars can be found clicking HERE..

 

Sincerely,
Organizers: Giulio Iacobelli e Maria Eulalia Vares

08 09 IM COLMEA noticiaTitulo:  Modeling the Spatio-temporal Spread of COVID-19 via a Reaction-diffusion System. 
Palestrante: Malú Grave (UFF)
Data: 13/09/2023
Horário: 14:30h
Local: Auditório RAV 62, 6o andar, Bloco F UERJ — Campus Maracanã Rua São Francisco Xavier, 524 Maracanã, Rio de Janeiro - RJ
 
Resumo: The COVID-19 outbreak in 2020 sparked significant interest in mathematical models of infectious diseases. These models categorize the population into compartments based on characteristics. While often expressed as ordinary differential equation (ODE) models, which depend solely on time, recent research has explored partial differential equation (PDE) models, particularly reaction-diffusion models that incorporate spatial variation in epidemics. These PDE models, within the Susceptible, Infected, Exposed, Recovered, and Deceased (SEIRD) framework, have shown promise in describing COVID-19’s progression. However, the rapid movement of people over long distances can result in nonlocal disease transmission, a phenomenon not well represented by diffusion alone. In contrast, ODE models can account for this by treating different regions as network nodes, connected by edges to represent nonlocal transmission. To address these complexities, a reaction-diffusion PDE model is developed with an integrated network structure. This approach aims to enhance our understanding and prediction of COVID-19 contagion dynamics in a more realistic and comprehensive way.

Titulo 2: Generation of Uniform Point Distributions on Hyper-Surfaces: Methods and Application
Palestrante: Lisandro Lovisolo (UERJ)
Data: 13/09/2023
Horário: 16:10h 
Local: Auditório RAV 62, 6o andar, Bloco F UERJ — Campus Maracanã Rua São Francisco Xavier, 524 Maracanã, Rio de Janeiro - RJ
 
Resumo: In many applications, it is necessary to obtain point arrangements on a hypersphere (or Nsphere) that are approximately uniform from a geometric perspective, i.e., with approximately constant angles between each point and its nearest neighbors. We discuss the use of these distributions in various applications. This problem is trivial in a two-dimensional space (N=2), and there are known solutions for certain quantities of points (K) in specific-dimensional spaces (N). On the other hand, the problem of selecting points uniformly distributed in a probabilistic sense is solved using Gaussian random variables. We describe how to generate geometric arrangements of approximately K uniformly distributed points on an N-sphere from uniform point distributions on the N-sphere.

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11 09 IM ProbabilitySeminar noticiaTítulo: Central Limit Theorem for the limit process of the discrete time RAP seen from the origin
Palestrante: Mariela Pentón Machado (IME-USP)
Data: 18/09/2023
Horário: 3:30 p.m. to 4:30 p.m.
Sala: C116 - Bloco C - CT – Instituto de Matemática – UFRJ. There will be no transmission online.


Resumo: Pablo Ferrari and Luiz Renato Fontes introduced The Random Average Process (RAP) in 98. We are interested in the discrete-time version of the RAP. This process is a random surface whose heights evolve taking a convex combination of the previous heights. In this dynamic, a random matrix of probabilities with independent and identically distributed rows determines the weights of the convex combinations. The process seen from the height in the origin is the random surface result of subtracting the height in the origin to all the heights in the initial surface. Under certain conditions, Ferrari and Fontes proved in 98 the existence of a limit process for the process seen from the height of the origin. In this talk I will discuss a Central Limit Theorem in the spacial variable for the limit process seen from  the height in the origin.  This is a joint work with Luiz Renato Fontes and Leonel Zuaznabar.

More complete information about the seminars can be found clicking HERE.

Sincerely,
Organizers: Giulio Iacobelli e Maria Eulalia Vares

30 08 IM Edital noticiaNÃO DEIXE DE ESTUDAR NA MELHOR UNIVERSIDADE FEDERAL DO BRASIL!!!!

São 25 Vagas
5 Para Cotas Raciais e 1 para cota PCD

Requisitos:
Ser professor de Matemática
Estar em efetivo exercício

Regras:
Vagas preferencialmente para Rede Pública de Ensino
Apenas no maximo 20% total das vagas preenchidas pela rede pública poderá ser prenchida com docentes da rede privada
contato: profmat@im.ufrj.br

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