Mathematical model of brain tumour with glia-neuron interactions and chemotherapy treatment

Acknowledgements This study was possible by partial financial support from the following Brazilian government agencies: Fundação Araucária, EPSRC-EP/I032606/1 and CNPq, CAPES and Science Without Borders Program Process nos. 17656125, 99999.010583/2013-00 and 245377/2012-3.Peer reviewedPreprin

Bacterial enzymatic activity and bioavailability of heavy metals in sediments from Boa Viagem Beach (Guanabara Bay)

This study focuses on the quality of the organic matter that reaches the sediment from Boa Viagem Beach and through the evaluation of the total bacterial count, the electron transport system activity (ETSA), the esterase activity (EST), as well as the protein and the organic matter contents. Seasonal variations of organic matter, protein content and the number of bacteria were particularly notable in the summer. ETSA reached a maximum of 7.48 µl O2 h-1 g-1 in the summer. EST activity presented a different pattern once it reached a maximum of 0.17 µg fluorescein h-1 g-1 in the winter. The temporal variation of ETSA and EST activity indicated that biopolymers predominated in the winter, and oligomers or monomers predominated in the summer. These results suggest that organic carbon turnover is more likely to be controlled by organic matter quality. The heavy metals concentrations, especially for Cu, Zn, Ni and Cr, indicated absence of the inhibition of dehydrogenase activity, and they are not bioavailable in the EC50 valuesO trabalho enfoca a qualidade da matéria orgânica do sedimento da Praia da Boa Viagem, avaliando-se a contagem de bactérias, a atividade do sistema transportador de elétrons (ETSA), a atividade de esterases (EST) e a concentração de proteína e matéria orgânica. Variação sazonal de matéria orgânica, de proteína e número de bactérias foi significativo no verão. ETSA apresentou maior valor no verão, 7.48 µl O2 h-1 g-1. A EST foi maior no inverno, chegando a 0.17 µg fluorescein h-1 g-1. A variação temporal de ETSA e EST indicaram que biopolímeros predominaram no inverno e oligômeros e monômeros, no verão. Estes resultados sugerem que a transformação do carbono orgânico é controlado pela qualidade da matéria orgânica. As concentrações dos metais, especialmente Cu, Zn, Ni and Cr, indicam ausência de inibição da atividade das desidrogenase pois não estão biodisponíveis na concentração EC50

Analytical solutions for the short-term plasticity

Acknowledgements This study was possible by partial financial support from the following Brazilian government agencies: FAPESP (2020/04624-2, 2022/05153-9, 2022/13761-9).Peer reviewe

Recurrence-based analysis of barrier breakup in the standard nontwist map

We wish to acknowledge the support: CNPq, CAPES, and FAPESP.Peer reviewedPublisher PD

Factors affecting the bacterial community composition and heterotrophic production of Columbia River estuarine turbidity maxima

© The Author(s), 2017. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in MicrobiologyOpen 6 (2017): e00522, doi:10.1002/mbo3.522.Estuarine turbidity maxima (ETM) function as hotspots of microbial activity and diversity in estuaries, yet, little is known about the temporal and spatial variability in ETM bacterial community composition. To determine which environmental factors affect ETM bacterial populations in the Columbia River estuary, we analyzed ETM bacterial community composition (Sanger sequencing and amplicon pyrosequencing of 16S rRNA gene) and bulk heterotrophic production (3H-leucine incorporation rates). We collected water 20 times to cover five ETM events and obtained 42 samples characterized by different salinities, turbidities, seasons, coastal regimes (upwelling vs. downwelling), locations, and particle size. Spring and summer populations were distinct. All May samples had similar bacterial community composition despite having different salinities (1–24 PSU), but summer non-ETM bacteria separated into marine, freshwater, and brackish assemblages. Summer ETM bacterial communities varied depending on coastal upwelling or downwelling conditions and on the sampling site location with respect to tidal intrusion during the previous neap tide. In contrast to ETM, whole (>0.2 μm) and free-living (0.2–3 μm) assemblages of non-ETM waters were similar to each other, indicating that particle-attached (>3 μm) non-ETM bacteria do not develop a distinct community. Brackish water type (ETM or non-ETM) is thus a major factor affecting particle-attached bacterial communities. Heterotrophic production was higher in particle-attached than free-living fractions in all brackish waters collected throughout the water column during the rise to decline of turbidity through an ETM event (i.e., ETM-impacted waters). However, free-living communities showed higher productivity prior to or after an ETM event (i.e., non-ETM-impacted waters). This study has thus found that Columbia River ETM bacterial communities vary based on seasons, salinity, sampling location, and particle size, with the existence of three particle types characterized by different bacterial communities in ETM, ETM-impacted, and non-ETM-impacted brackish waters. Taxonomic analysis suggests that ETM key biological function is to remineralize organic matter.National Science Foundation Grant Number: OCE-042460

Plastic neural network with transmission delays promotes equivalence between function and structure

Acknowledgements The authors acknowledge the financial support from São Paulo Research Foundation (FAPESP, Brazil) (Grants Nos. 2016/23398-8, 2017/13502-5, 2018/03211-6, 2020/04624-2, 2022/05153-9, 2022/13761-9), National Council for Scientific and Technological Development (CNPq), Fundação Araucária and Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - Brasil (CAPES) .Peer reviewedPublisher PD

Search for bioindicators of pollution in the Guanabara Bay: integrations of ecologic patterns

Guanabara Bay, since its discovery, has largely changed with the human occupation causing large amounts of deposited sediment and waste, as well as domestic and industry sewage. Surface sediment was analysed for foraminifera and ostracoda distribution, diversity and dominance studies. These results were compared with TOC analyses aiming the determination of pollution bioindicators. In general, foraminifera dominant species were Ammonia tepida, Buliminella elegantissima and Quinqueloculina seminulum. The foraminifera assemblages presented distinct abundance and diversity values in different regions of the bay. The diversity was higher in the entrance (south) and in the central region than in the north region of the bay. The dominant species, that are characteristic of stressed environments, presented higher values of abundance in the north region. The TOC values increased from south to north regions, and were inversely proportional to foraminifera diversity. The very high TOC values in very polluted areas suggest sediment deposition in anoxic-dysoxic environment. The ostracoda Gen. Cyprideis was dominant and its occurrence increased from south to north region. Occurrence of Callistocythere sigmocostata, Xestoleberis sp., Aurila sp., and Paracypris sp. were restricted to the entrance and central area, indicating a preference for less restricted conditions, like marine conditions. Foraminifera and ostracoda characteristic responses to the environment conditions related high TOC values showed their importance as bioindicators of stressed environments caused by anthropogenic pollution, in the Guanabara Bay.A Baía de Guanabara, desde o seu descobrimento, tem sido bastante modificada pela ocupação humana, causando o acúmulo de grande quantidade de sedimento depositado e lixo, bem como lançamento de esgotos domésticos e industriais. Sedimentos superficiais foram analisados visando o estudo da distribuição, diversidade e dominância de foraminíferos e ostracodes. Estes estudos foram comparados com análises de COT objetivando a determinação de bioindicadores de poluição. Em geral as espécies dominantes de foraminíferos foram Ammonia tepida,Buliminella elegantissima and Quinqueloculina seminulum. As associações de foraminíferos apresentam distintos valores de abundância e diversidade em diferentes regiões da Baía. A diversidade foi mais elevada na entrada (sul) e na região central do que na região norte da Baía. As espécies dominantes, que são características de ambientes sob estresse, apresentaram valores altos de abundância na região norte. Os valores de COT aumentaram da região sul para o norte e foram inversamente proporcionais à diversidade de foraminíferos. O elevados valores de COT em áreas muito poluídas sugerem deposição sedimentar em ambiente anóxico-desóxico. O Gen. Cyprideis, de ostracode, foi dominante e sua ocorrência aumentou da região sul para o norte. A ocorrência de Callistocythere sigmocostata, Xestoleberis sp., Aurila sp. e Paracypris sp. foi estrita à entrada e região central, indicando uma preferência por condições menos restritas, como condições marinhas. As respostas características dos foraminíferos e ostracodes às condições ambientais relacionadas aos elevados valores de COT mostraram sua importância como bioindicadores de ambientes sob estresse causado por poluição antropogênica na Baía de Guanabara

Influence of Delayed Conductance on Neuronal Synchronization

In the brain, the excitation-inhibition balance prevents abnormal synchronous behavior. However, known synaptic conductance intensity can be insufficient to account for the undesired synchronization. Due to this fact, we consider time delay in excitatory and inhibitory conductances and study its effect on the neuronal synchronization. In this work, we build a neuronal network composed of adaptive integrate-and-fire neurons coupled by means of delayed conductances. We observe that the time delay in the excitatory and inhibitory conductivities can alter both the state of the collective behavior (synchronous or desynchronous) and its type (spike or burst). For the weak coupling regime, we find that synchronization appears associated with neurons behaving with extremes highest and lowest mean firing frequency, in contrast to when desynchronization is present when neurons do not exhibit extreme values for the firing frequency. Synchronization can also be characterized by neurons presenting either the highest or the lowest levels in the mean synaptic current. For the strong coupling, synchronous burst activities can occur for delays in the inhibitory conductivity. For approximately equal-length delays in the excitatory and inhibitory conductances, desynchronous spikes activities are identified for both weak and strong coupling regimes. Therefore, our results show that not only the conductance intensity, but also short delays in the inhibitory conductance are relevant to avoid abnormal neuronal synchronization.Peer Reviewe

Structural connectivity modifications in the brain of selected patients with tumour after its removal by surgery (a case study)

Acknowledgments This study was possible by partial financial support from the following agencies: Funda¸c˜ao Arauc´aria, Brazilian National Council for Scientific and Technological Development (CNPq), and Coordination for the Improvement of Higher Education Personnel (CAPES). S˜ao Paulo Research Foundation (FAPESP 2018/03211-6, 2022/13761-9). We thank 105 Group Science (www.105groupscience.com).Peer reviewe