Statistical Complexity and Nontrivial Collective Behavior in Electroencephalografic Signals

We calculate a measure of statistical complexity from the global dynamics of electroencephalographic (EEG) signals from healthy subjects and epileptic patients, and are able to stablish a criterion to characterize the collective behavior in both groups of individuals. It is found that the collective dynamics of EEG signals possess relative higher values of complexity for healthy subjects in comparison to that for epileptic patients. To interpret these results, we propose a model of a network of coupled chaotic maps where we calculate the complexity as a function of a parameter and relate this measure with the emergence of nontrivial collective behavior in the system. Our results show that the presence of nontrivial collective behavior is associated to high values of complexity; thus suggesting that similar dynamical collective process may take place in the human brain. Our findings also suggest that epilepsy is a degenerative illness related to the loss of complexity in the brain.Comment: 13 pages, 3 figure

Greenhouse gases from membrane bioreactor treating hydrocarbon and saline wastewater

The effect of wastewater salinity and presence of petroleum hydrocarbon on N2O emission was investigated in a membrane bioreactor, in which the anoxic and aerobic zones were put in series according to a pre-denitrification scheme. The pilot plant, was continuously fed by a mixture of real and synthetic wastewater. It was operated with a first phase of acclimation of the biomass to a given salinity by gradually increasing the salt concentration from 10 gNaCl/L to 20 gNaCl/L, and to a second phase of petroleum hydrocarbon dosing at 2 g/L (as gasoline). The first phase revealed a clear relationship between nitrous oxide emissions and salinity due to the increased NO2-N production caused by the stress induced both on autotrophic and heterotrophic biomass by the increased salinity. However, after 45 days of operation, the growth rate of the autotrophic species started to recover, indicating acclimatization of the nitrifiers. In the second phase, the hydrocarbon shock induced a temporary complete inhibition of the biological activities, as well as the temporary suppression of the N2O emissions. The observations in this study revealed that the oxic tank is the major source in terms of nitrous oxide emission flux. Indeed the aerobic tank emitted 1 or 2 order of magnitude more than the anoxic one. The reason of this is likely due to the stripping of the gas by aeration

Nitrous oxide from moving bed based integrated fixed film activated sludge membrane bioreactors

The present paper reports the results of a nitrous oxide (N2O) production investigation in a moving bed based integrated fixed film activated sludge (IFAS) membrane bioreactor (MBR) pilot plant designed in accordance with the University of Cape Town layout for biological phosphorous removal. Gaseous and liquid samples were collected in order to measure the gaseous as well as the dissolved concentration of N2O. Furthermore, the gas flow rate from each reactor was measured and the gas flux was estimated. The results confirmed that the anoxic reactor represents the main source of nitrous oxide production. A significant production of N2O was, however, also found in the anaerobic reactor, thus indicating a probable occurrence of the denitrifying phosphate accumulating organism activity. The highest N2O fluxes were emitted from the aerated reactors (3.09 g N2O[sbnd]N m 122 h 121 and 9.87 g N2O[sbnd]N m 122 h 121, aerobic and MBR tank, respectively). The emission factor highlighted that only 1% of the total treated nitrogen was emitted from the pilot plant. Furthermore, the measured N2O concentrations in the permeate flow were comparable with other reactors. Nitrous oxide mass balances outlined a moderate production also in the MBR reactor despite the low hydraulic retention time. On the other hand, the mass balance showed that in the aerobic reactor a constant consumption of nitrous oxide (up to almost 15 mg N2O h 121) took place, due to the high amount of stripped gas

UCT-MBR vs IFAS-UCT-MBR for Wastewater Treatment: A Comprehensive Comparison Including N2O Emission

In this study the performance (in terms of carbon and nutrient removal) and N2O emission of two plant configurations adopting innovative technologies were investigated. With this regards, an University Cape Town (UCT) membrane bioreactor (MBR) plant and an Integrated Fixed Film Activated Sludge (IFAS) -UCT-MBR plant were monitored. Both plants treat real wastewater under two different values of the influent carbon nitrogen ratio (C/N = 5 mgCOD/mgN and C/N = 10 mgCOD/mgN). Results have shown the highest carbon and nutrients removal efficiencies for the IFAS-UCT-MBR configuration during both the two investigated C/N values. Furthermore, the lowest N2O emission occurred for the IFAS-UCT-MBR

Periodic Neural Activity Induced by Network Complexity

We study a model for neural activity on the small-world topology of Watts and Strogatz and on the scale-free topology of Barab\'asi and Albert. We find that the topology of the network connections may spontaneously induce periodic neural activity, contrasting with chaotic neural activities exhibited by regular topologies. Periodic activity exists only for relatively small networks and occurs with higher probability when the rewiring probability is larger. The average length of the periods increases with the square root of the network size.Comment: 4 pages, 5 figure

Intracultural diversity in a model of social dynamics

We study the consequences of introducing individual nonconformity in social interactions, based on Axelrod's model for the dissemination of culture. A constraint on the number of situations in which interaction may take place is introduced in order to lift the unavoidable ho mogeneity present in the final configurations arising in Axelrod's related models. The inclusion of this constraint leads to the occurrence of complex patterns of intracultural diversity whose statistical properties and spatial distribution are characterized by means of the concepts of cultural affinity and cultural cli ne. It is found that the relevant quantity that determines the properties of intracultural diversity is given by the fraction of cultural features that characterizes the cultural nonconformity of individuals.Comment: 7 pages, 2 tables, 6 figure

Nitrous oxide emissions in a membrane bioreactor treating saline wastewater contaminated by hydrocarbons

The joint effect of wastewater salinity and hydrocarbons on nitrous oxide emission was investigated. The membrane bioreactor pilot plant was operated with two phases: i. biomass acclimation by increasing salinity from 10 gNaCl L−1 to 20 gNaCl L−1 (Phase I); ii. hydrocarbons dosing at 20 mg L−1 with a constant salt concentration of 20 gNaCl L−1 (Phase II). The Phase I revealed a relationship between nitrous oxide emissions and salinity. During the end of the Phase I, the activity of nitrifiers started to recover, indicating a partial acclimatization. During the Phase II, the hydrocarbon shock induced a temporary inhibition of the biomass with the suppression of nitrous oxide emissions. The results revealed that the oxic tank was the major source of nitrous oxide emission, likely due to the gas stripping by aeration. The joint effect of salinity and hydrocarbons was found to be crucial for the production of nitrous oxid

Greenhouse gas from moving bed based integrated fixed film activated sludge membrane bioreactors

The present paper reports the results of a nitrous oxide production investigation in a moving bed based integrated fixed film activated sludge (IFAS) membrane bioreactor (MBR) pilot plant designed in accordance with the UCT layout for biological phosphorous removal. Samples of gas and liquid were collected in order to measure the gaseous, as well as the dissolved concentration of N2O. Furthermore, the gas flow rate from each reactor was measured and the gas flux was estimated. The results confirmed that the anoxic reactor represents the main source of nitrous oxide production. A significant production of N2O was, however, also found in the anaerobic reactor, thus indicating a probable occurrence of the DPAOs activity

Comportamento e controle do gafanhoto RHAMMATOCERUS SCHISTOCERCOIDES (REHN, 1906) no Mato Grosso.

- Ern setembro de 1984, verificou-se uma explosão populacional da especie do gafanhoto Rhammatocerus schistocercoides (Rehn, 1906) no estado de Mato Grosso. 0 estudo da biologia em condicoes de laboratorio, casa de vegetario e campo revelou que a postura ocorre ern outubro-novembro e as ninfas emergern ern novembro-dezembro. Cada instar tem, em media, 26 dias, havendo cinco instares nas condicoes de Mato Grosso e seis instares nas condicoes do Distrito Federal. Transformarn-se ern adultos ern abril, n-ligratn ern agosto-setembro, e o acasalamento ocorre em setembro-outubro. Preferência alimentar: 0 R. schistocercoides prefere, ern primeiro lugar, gramineas nativas do cerrado e campo sujo, seguindo-se as culturas de arroz, cana-de-acucar, milho, sorgo, pastagens e, por firn, soja e feijão. Controle quimico: Foram testados para, o Controle do gafanhoto adulto os inseticidas: fenitrothion, malathion, carbaril, esfenvarelate e fenvarelate. 0 carbaril e os piretroides não foram eficientes nas clonagens testadas. 0 fenitrothion e o malathion mostraram acima de 98% da eficiencia nas dosagens de 300 g do i.a. e 800 g do i.a. por ha, respectivamente. Posteriormente se testou o fenitrothion dflufdo ern 61eo de algodão (50%), mostrando uma eficiência de 95% na dosagern de 150 g do La. por ha.Título em inglês: Behavior and control of the locust RHAMMATOCERUS SCHISTOCERCOIDES (REHN, 1906) in Mato Grosso, Brazil

Coupled Maps on Trees

We study coupled maps on a Cayley tree, with local (nearest-neighbor) interactions, and with a variety of boundary conditions. The homogeneous state (where every lattice site has the same value) and the node-synchronized state (where sites of a given generation have the same value) are both shown to occur for particular values of the parameters and coupling constants. We study the stability of these states and their domains of attraction. As the number of sites that become synchronized is much higher compared to that on a regular lattice, control is easier to effect. A general procedure is given to deduce the eigenvalue spectrum for these states. Perturbations of the synchronized state lead to different spatio-temporal structures. We find that a mean-field like treatment is valid on this (effectively infinite dimensional) lattice.Comment: latex file (25 pages), 4 figures included. To be published in Phys. Rev.