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O Programa de Pós-Graduação em Física e o Parque Viva Ciência convidam a todos para:
Planetas extrassolares e vida no universo
Professor Roberto Saito
A vida como conhecemos é um fenômeno planetário até o momento limitado ao nosso lar no Universo, a Terra. Entretanto, nas últimas duas décadas a astronomia vem passando por um momento único, com a descoberta de um número cada vez maior de planetas orbitando outras estrelas, os chamados planetas extrassolares. Alguns desses novos mundos são especialmente importantes por suas similaridades com a
Terra, o que permitiria abrigar vida. Nesse seminário falaremos sobre a busca e o estudo de planetas extrassolares, nosso conhecimento atual sobre exoplanetas potencialmente habitáveis e as perspectivas que a busca por vida fora da Terra nos reservam nas próximas décadas.
Data e horário: 15 de março de 2017, às 18:30h
Local: Auditório do Depto. de Química
EL PROGRAMA DE POSGRADO EN FÍSICA invita a todos para lo seminario:
Phase transitions and self-organized criticality in networks of stochastic spiking neurons.
Prof. Dr. Osame Kinouchi
Departamento de Física – FFCLRP – USP
Resumen:
Phase transitions and critical behavior are crucial issues both in theoretical and experimental neuroscience. We report analytic and computational results about phase transitions and self-organized criticality (SOC) in networks with general stochastic neurons. The stochastic neuron has a firing probability given by a smooth monotonic function Phi(V) of the membrane potential V, rather than a sharp firing threshold. We find that such networks can operate in several dynamic regimes (phases) depending on the average synaptic weight and the shape of the firing function Phi. In particular, we encounter both continuous and discontinuous phase transitions to absorbing states. At the continuous transition critical boundary, neuronal avalanches occur whose distributions of size and duration are given by power laws, as observed in biological neural networks. We also propose and test a new mechanism to produce SOC: the use of dynamic neuronal gains — a form of short-term plasticity probably in the axon initial segment (AIS) — instead of depressing synapses at the dendrites (as previously studied in the literature). The new self-organization mechanism produces a slightly supercritical state, that we called SOSC, in accord to some intuitions of Alan Turing.
Fecha: 19 de deciembre de 2016- (lunes) – Lugar: Sala 212 – Auditorio del Departamento de Física – Horário: 10h30min
EL PROGRAMA DE POSGRADO EN FÍSICA invita a todos para lo seminario:
Kelvin: past, present and future.
Prof.
Departamento de Física/UFPR
Resumen:
Four basic physical units of SI, viz., kilogram, ampere, mole, and kelvin will be redefined in 2018. Their definitions will be related to universal physical constants such as Planck constant, elementary charge, number of Avogadro and Boltzmann constant. At the moment, great efforts are being done to measure these constants with a high accuracy. The lecture gives a brief history of the kelvin definition. Its future definition via the Boltzmann constant will be presented. Experimental and theoretical results related to the future definition of kelvin are reviewed.
Fecha: 6 de diciembre de 2016- (martes) – Lugar: Sala 212 – Auditorio del Departamento de Física – Horário: 14 horas
