Contributions of the complexity paradigm to the understanding of Cerrado's organization and dynamics.

The Brazilian Cerrado is a vegetation mosaic composed of different physiognomies. Discussions remain open regarding the factors and processes responsible for the dynamic and spatial organization of the Cerrado - in its different physiognomies. The contributions of the complexity paradigm in this context are still less exploited, despite its great potential for explanations and predictions presented in previous diverse dynamic systems of complex behavior researches, a category in which the Cerrado can be included. This article has the intention of contributing to the construction of this new perspective, discussing - from theoretical concepts - the paradigm of complexity for the understanding of the organization and the dynamics of the Cerrado.

Vaccination and social distance to prevent COVID-19.

In order to analyze the effect of vaccination in a population with the presence of viruses, a variation of the SIR (Susceptible-Infected-Removed) model is proposed taking into account social distancing and the effect of the vaccine. The equilibrium points of the proposed model are calculated and the stability analysis of the system is carried out. For the proposed model, disease-free equilibrium point and endemic equilibrium point are found and the conditions of existence are discussed. For the disease-free equilibrium point the bifurcation conditions are derived and simulations show that reducing the vaccination effort can lead the disease-free equilibrium to the endemic equilibrium. From the theoretical analysis, a minimum value of effort is obtained to guarantee a disease-free equilibrium point. Simulations were carried out from the value obtained from Rv to validate the theoretical results.

The synergetic modulation of the excitability of central gray matter by a neuropeptide: two protocols using excitation waves in chick retina.

The isolated chick retina provides an in vitro tissue model, in which two protocols were developed to verify the efficacy of a peptide in the excitability control of the central gray matter. In the first, extra-cellular potassium homeostasis is challenged at long intervals and in the second, a wave is trapped in a ring of tissue causing the system to be under self-sustained challenge. Within the neuropil, the extra-cellular potassium transient observed in the first protocol was affected from the initial rising phase to the final concentration at the end of the five-minute pulse. There was no change in the concomitants of excitation waves elicited by the extra-cellular rise of potassium. However, there was an increase on the elicited waves latency and/or a rise in the threshold potassium concentration for these waves to appear. In the second protocol, the wave concomitants and the propagation velocity were affected by the peptide. The results suggest a synergetic action of the peptide on glial and synaptic membranes: by accelerating the glial Na/KATPase and changing the kinetics of the glial potassium channels, with glia tending to accumulate KCl. At the same time, there is an increase in potassium currents through nerve terminals.

Measuring complexity in Brazilian economic crises.

Capital flows are responsible for a strong influence on the foreign exchange rates and stock prices macroeconomic parameters. In volatile economies, capital flows can change due to several types of social, political and economic events, provoking oscillations on these parameters, which are recognized as economic crises. This work aims to investigate how these two macroeconomic variables are related with crisis events by using the traditional complex measures due to Lopez-Mancini-Calbet (LMC) and to Shiner-Davison-Landsberg (SDL), that can be applied to any temporal series. Here, Ibovespa (Bovespa Stock Exchange main Index) and the "dollar-real" parity are the background for calculating the LMC and SDL complexity measures. By analyzing the temporal evolution of these measures, it is shown that they might be related to important events that occurred in the Brazilian economy.

Phase Oscillatory Network and Visual Pattern Recognition.

We explore a properly interconnected set of Kuramoto type oscillators that results in a new associative-memory network configuration, which includes second- and third-order additional terms in the Fourier expansion of the network's coupling. Investigation of the response of the network to different external stimuli indicates an increase in the network capability for coding and information retrieval. Comparison of the network output with that of an equivalent experiment with subjects, for recognizing perturbed binary patterns, shows comparable results between the two approaches. We also discuss the enhanced storage capacity of the network.

Bits and q-bits as versatility measures.

Using Shannon information theory is a common strategy to measure any kind of variability in a signal or phenomenon. Some methods were developed to adapt information entropy measures to bird song data trying to emphasize its versatility aspect. This classical approach, using the concept of bit, produces interesting results. Now, the original idea developed in this paper is to use the quantum information theory and the quantum bit (q-bit) concept in order to provide a more complete vision of the experimental results.

The synergetic modulation of the excitability of central gray matter by a neuropeptide: two protocols using excitation waves in chick retina

The isolated chick retina provides an in vitro tissue model, in which two protocols were developed to verify the efficacy of a peptide in the excitability control of the central gray matter. In the first, extra-cellular potassium homeostasis is challenged at long intervals and in the second, a wave is trapped in a ring of tissue causing the system to be under self-sustained challenge. Within the neuropil, the extra-cellular potassium transient observed in the first protocol was affected from the initial rising phase to the final concentration at the end of the five-minute pulse. There was no change in the concomitants of excitation waves elicited by the extra-cellular rise of potassium. However, there was an increase on the elicited waves latency and/or a rise in the threshold potassium concentration for these waves to appear. In the second protocol, the wave concomitants and the propagation velocity were affected by the peptide. The results suggest a synergetic action of the peptide on glial and synaptic membranes: by accelerating the glial Na/KATPase and changing the kinetics of the glial potassium channels, with glia tending to accumulate KCl. At the same time, there is an increase in potassium currents through nerve terminals.

Retinas de pinto isoladas proporcionam um modelo de tecidos in vitro, para o qual dois protocolos foram desenvolvidos para verificar a eficácia de um peptídeo no controle da excitabilidade da matéria cinzenta central. No primeiro, a homeostase do potássio extra-celular é desafiada por intervalos longos (1 hora) e no segundo, uma onda é capturada em um anel de tecido, de tal maneira que o sistema permaneça em estado de desafio auto-sustentado. Dentro da neuropil, o transiente de potássio extra-celular observado no primeiro protocolo foi afetado da fase de início de aumento à concentração final, ao final do pulso de cinco minutos. Não há mudanças nos parâmetros concomitantes das ondas de excitação geradas pelo aumento do potássio extra-celular. Entretanto, houve um aumento da latência das ondas geradas e/ou um aumento no nível de concentração de potássio necessário para gerar a onda. No segundo protocolo, os parâmetros concomitantes da onda e sua velocidade de propagação foram afetados pelo peptídeo. Os resultados sugerem uma ação sinergética do peptídeo nas membranas gliais e sinápticas: acelerando o Na/KATPase glial e mudando a cinética dos canais de potássio gliais, com a glia tendendo a acumular KCl. Nesse período, não há aumento nas correntes de potássio nas terminações nervosas.

Bits and q-bits as versatility measures

Usar a teoria da informação de Shannon é uma estratégia comum para medir todo tipo de variabilidade em um sinal ou fenômeno. Alguns métodos foram desenvolvidos para adaptar a medida de entropia informacional a dados de cantos de pássaro, tentando enfatizar seus aspectos de versatilidade. Essa abordagem clássica, usando o conceito de bit, produz resultados interessantes. Agora, a idéia original desenvolvida neste artigo é usar a teoria quântica da informação e o conceito de q-bit, com a finalidade de proporcionar uma visão mais completa dos resultados experimentais.

Consciousness and controllability: looking for a legitimate temporal code in the brain

Consciousness can be treated as a process by which the central nervous system controls unstable or nonconvergent varieties of representations. Translated into voluntary control over actions, consciousness, in this aspect, may represent a style of computation that works over unstable objects. Through the synchronized combination of modalities of oscillations, we internalize blocks of ordinary language, having the sensation that our mental representations are propositional and nonreducible to cerebral events. Bifurcations and chaos at hte neural level of processing can be candidates to the events that summon conscious control to exert its role. The function of consciousness would be resetting nonconvergent series of events; the form by which it works can be seen as a type of topological computation that appears in phase-transitions; the contents of consciousness are oscillations and synchronization that couple several series of processes and their possible descriptions in ordinary language; the primary feeling of being conscious, qualia, is an emergent property of large amounts of oscillating neuronal assemblies that are recruited during the propagation of an error signal among different loops that try to solve the task. The sensation of volunteerism and of free will is compatible with a deterministic, nonmechanic, view of the process in which consciousness exerts control, vetoing or allowing presumed actions and interpretations of perceptions to go on.