Two distinct desynchronization processes caused by lesions in globally coupled neurons

To accomplish a task, the brain works like a synchronized neuronal network where all the involved neurons work together. When a lesion spreads in the brain, depending on its evolution, it can reach a significant portion of relevant area. As a consequence, a phase transition might occur: the neurons desynchronize and cannot perform a certain task anymore. Lesions are responsible for either disrupting the neuronal connections or, in some cases, for killing the neuron. In this work, we will use a simplified model of neuronal network to show that these two types of lesions cause different types of desynchronization.Comment: 5 pages, 3 figure

Phase synchronization of coupled bursting neurons and the generalized Kuramoto model

Bursting neurons fire rapid sequences of action potential spikes followed by a quiescent period. The basic dynamical mechanism of bursting is the slow currents that modulate a fast spiking activity caused by rapid ionic currents. Minimal models of bursting neurons must include both effects. We considered one of these models and its relation with a generalized Kuramoto model, thanks to the definition of a geometrical phase for bursting and a corresponding frequency. We considered neuronal networks with different connection topologies and investigated the transition from a non-synchronized to a partially phase-synchronized state as the coupling strength is varied. The numerically determined critical coupling strength value for this transition to occur is compared with theoretical results valid for the generalized Kuramoto model.Comment: 31 pages, 5 figure

Modelos matemáticos para lesões em redes neurais com padrões complexos de conectividade

Orientador: Prof. Dr. Ricardo Luiz VianaTese (Doutorado) - Universidade Federal do Paraná, Setor de Ciências Exatas, Programa de Pós-Graduação em Física. Defesa: Curitiba, 18/09/2015Inclui referências : f. 139-146Resumo: O cérebro contem cerca de cem bilhões de neurônios que se conectam através de um padrão complexo de conectividade, que opera no sentido de otimizar o processo de transmissão de informação. Os neurônios, ao estabelecerem uma conexão entre si podem muitas vezes exibir sincronização. A presença de traumas e doenças degenerativas em regiões específicas do cérebro podem, através de efeitos locais, danificar o funcionamento cerebral como um todo. O propósito deste trabalho é tentar responder a questões do tipo: em uma rede neural, quais são as formas de lesões que causam maior impacto na dinâmica da rede? É possível identificar um tipo de lesão a partir do seu efeito? Existem topologias de rede que são mais robustas à lesões? Neste sentido, analisamos a sincronização de fase para uma rede de neurônios com diferentes topologias de rede, comparamos os resultados com um modelo de osciladores e analisamos diferentes tipos de lesões. Nossos resultados apontam que para o estudo de sincronização de fase, os neurônios podem ser considerados como osciladores, porém, o comportamento das frequências no estado sincronizado em redes neurais, em geral, não é similar ao comportamento de osciladores. No estudo das lesões, do ponto de vista dinâmico, para cada tipo de rede existe um comportamento distinto aos diferentes tipos de lesões. Entre neurônios globalmente acoplados, é possível distinguir a partir da dinâmica global se a lesão destrói apenas as conexões ou destrói os neurônios. Em redes complexas, o efeito das lesões é maior quando a lesão afeta os neurônios mais conectados ou com maior centralidade de intermediação. Em redes de pequeno mundo, a diferença entre os tipos de lesão é perceptível, porém, mais sutil do que para redes aleatórias e sem escala.Abstract: The brain is composed of around one hundread billion of neurons connected through synapses forming a complex pattern of connectivity. This complex connectivity is responsible to optimize the information process. When neurons are connected among themselves they can exhibit synchronization. The presence of traumas and neurodegenerative diseases in some brain areas causes not only local effects, but in the whole brain. The purpose of this work is to answer questions like: which are the type of lesions with bigger dynamical effects in the neural network? Is it possible to identify a type of lesion just looking at its dynamical effects in the network? Are there topologies against lesions which are more robust than others? In this sense, we analyse phase synchronization in a neural network with different network topologies. We compare the obtained results with a model of phase oscillators and we analysed different types of lesions. Our results show that neuronal phase synchronization is similar to phase synchronization in oscillators, however, frequency synchronization usually is different in both models. Related to lesions, from the dynamical point of view, for each type of network there is a distinct behavior for each type of lesion. Among globally coupled neurons, it is possible to dynamically distinguish when the lesion either disrupt or destroy the neurons. For complex networks, the most effective lesions are those that affects the most connected neurons or those with the largest betweenness. For small-world networks, the difference among types of lesions are distinguishable, though, they are subtle in comparison with random and scale-free networks

Natural language processing for requirements engineering: The best is yet to come

As part of the growing interest in natural language processing for requirements engineering (RE), RE researchers, computational linguists, and industry practitioners met at the First Workshop on Natural Language Processing for Requirements Engineering (NLP4RE 18). This article summarizes the workshop and presents an overview of the discussion held on the field’s future. This article is part of a theme issue on software engineering’s 50th anniversary.Postprint (author's final draft

A set of metrics for characterizing simulink model comprehension

Simulink is a powerful tool for Embedded Systems, playing a key role in dynamic systems modeling. However, far too little attention has been paid to quality of Simulink models. In addition, no research has been found linking the relationship between model complexity and its impact in the comprehension quality of Simulink models. The aim of this paper is to define a set of metrics to support the characterization of Simulink models and to investigate their relationship with the model comprehension property. For this study, we performed a controlled experiment using two versions of a robotic Simulink model — one of them was constructed through the ad hoc development approach and the other one through the re-engineered development approach. The results of the experiment show that the re-engineered model is more comprehensible than the ad hoc model. In summary, the set of metrics collected from each version of the Simulink model suggests an inverse relationship with the model comprehension, i.e., the lower the metrics, the greater the model comprehension.Facultad de Informátic

A set of metrics for characterizing simulink model comprehension

Simulink is a powerful tool for Embedded Systems, playing a key role in dynamic systems modeling. However, far too little attention has been paid to quality of Simulink models. In addition, no research has been found linking the relationship between model complexity and its impact in the comprehension quality of Simulink models. The aim of this paper is to define a set of metrics to support the characterization of Simulink models and to investigate their relationship with the model comprehension property. For this study, we performed a controlled experiment using two versions of a robotic Simulink model — one of them was constructed through the ad hoc development approach and the other one through the re-engineered development approach. The results of the experiment show that the re-engineered model is more comprehensible than the ad hoc model. In summary, the set of metrics collected from each version of the Simulink model suggests an inverse relationship with the model comprehension, i.e., the lower the metrics, the greater the model comprehension.Facultad de Informátic

SUSTENTABILIDADE NAS EDIFICAÇÕES: REVISÃO BIBLIOGRÁFICA SOBRE PRÉDIO VERDE

O privilégio de se adotar novas medidas para um ambiente mais sustentável traz redução no impacto ambiental, economia de gastos e oferece para o usuário melhoria no conforto térmico. Utilizou-se como metodologia, análise de livros e artigos que abordam o tema sustentabilidade, principalmente no que se refere aos prédios verdes. Sendo assim, objetivou-se com este estudo, promover uma revisão bibliográfica sobre Prédio Verde a fim de melhorar as condições de sustentabilidade nas edificações

Conflitos no Uso e Cobertura da Terra no Município de Nova Palma, RS

This work has as main objective, to check if the subjects of use ofland in areas of permanent preservation, over the rivers and the slopes arein accordance with the Forest Code (Law number 4771 of September 15,1965), in the city of Nova Palma-RS. The methodology adopted is guidedin the implementation of a database in a GIS (Geographic InformationSystems) using the software SPRING 4.2.3. The layers, kinds of use ofland and the areas recommended for permanent preservation, wereoverlapping using is the language LEGAL (Language Space for AlgebricGeoprocessing). Identified in the areas of permanent preservation alongthe drainage, 7.73 km² area with crops and 3.36 km² of field. Already on slopes above 45 degrees were a total area of 2.74 km² with agricultural crops.O presente trabalho tem como objetivo principal verificar se ostemas de uso da terra, nas áreas de preservação permanente, ao longo doscursos d’água e nas encostas, estão de acordo com o Código Florestal (Leinº 4.771 de 15/09/1965) no município de Nova Palma - RS. A metodologiaadotada pautou-se na implementação de um banco de dados num SIG (Sistemasde Informações Geográficas) no aplicativo computacional SPRING4.2.3. Os planos de informações, classes de uso da terra e as áreas recomendadasà preservação permanente, foram sobrepostos, utilizando-se da linguagemLEGAL (Linguagem Espacial para Geoprocessamento Algébrico).Identificou-se nas áreas de preservação permanente ao longo da drenagem,7,73 Km² de área com culturas agrícolas e 3,36 Km² de campo. Já nas encostasacima de 45°, constatou-se uma área total de 2,74 Km² com culturasagrícolas

CULTIVO DE CANAFÍSTULA (Peltophorum dubium) EM MINIJARDIM CLONAL E PROPAGAÇÃO POR MINIESTACAS

The present work aimed to evaluate the behavior of canafistula, established in mini-clonal hedge system and the viability of applying the mini-cutting technique for vegetative propagation of this species. In the formation of mini-stumps, of seminal origin, different numbers of leaves were maintained (three or more leaves, one, or a pair of leaves). It was evaluated the survival of mini-stumps, number, length and diameter of shoots and average productivity of mini-cuttings by mini-stumps during the successive regrowth. The effect of the application of IBA (0, 1500, 3000, 4500 and 6000 mg L-1) on survival and rooting of basal and apical mini-cuttings were also evaluated. The mini-stumps survival was 100% regardless of the number of leaves remaining in its formation. The maintenance of one leaf allowed the formation of a larger number of shoots (3.39) per mini-stump, 1 pair of leaves promoted greater shoot length (12.41 cm), and with three or more leaves, the shoots had larger diameters. The average production of mini-cuttings/mini-stump/harvesting has been growing over the successive regrowth, with maximum yield (159 mini-cuttings m-2) observed on the 4th regrowth. Apical mini-cuttings show higher rooting potential than the basal. The IBA is dispensable in the radicial induction but stimulates the root dried mass. The cultivation of the canafistula in mini-clonal hedge system enables the production of shoots for clonal propagation through mini-cuttings.O objetivo deste trabalho foi avaliar o comportamento da canafístula (Peltophorum dubium Spreg. Taub.) cultivada em sistema de minijardim clonal e estudar a viabilidade da aplicação da técnica de miniestaquia para a propagação vegetativa desta espécie. Na formação das minicepas, de origem seminal, mantiveram-se diferentes números de folhas (três ou mais, uma folha ou um par de folhas). Avaliou-se a sobrevivência das minicepas, número, comprimento e diâmetro dos brotos e a produtividade média de miniestacas por minicepa durante sucessivas rebrotas. Avaliou-se ainda o efeito da aplicação do AIB (0; 1500; 3000; 4500 e 6000 mg L-1) sobre a sobrevivência e o enraizamento de miniestacas basais e apicais. A sobrevivência das minicepas foi de 100% independentemente do número remanescente de folhas na sua formação. A manutenção de 1 folha possibilitou a formação de maior número de brotos (3,39) por minicepa; 1 par de folhas promoveu maior comprimento dos brotos (12,41 cm) e; 3 folhas ou mais originaram brotos de maior diâmetro. A produção média de miniestacas/minicepa/coleta foi crescente ao longo das sucessivas rebrotas, com máxima produtividade (159 miniestacas m-2) na 4ª rebrota. Miniestacas apicais apresentam maior potencial de enraizamento do que as basais. O AIB é dispensável na indução radicial, mas estimula a produção de massa seca das raízes. O manejo da canafístula em sistema de minijardim clonal possibilita a produção de brotos para processos de propagação clonal através da miniestaquia