Ephaptic Coupling in Hybrid Neuronal Model

In recent decades, there has been growing interest in the impact of electric fields generated in the brain. Transmembrane ionic currents originate electric fields in the extracellular space and are capable of affecting nearby neurons, a phenomenon called ephaptic neuronal communication. In the present work, the Quadratic Integrate-and-Trigger model (QIF-E) underwent an adjustment/improvement to include the ephaptic coupling behavior between neurons and their results are compared to the empirical results. In this way, the analysis tools are employed according to the neuronal activity regime: (i) for the subthreshold regime, the circular statistic is used to describe the phase differences between the input stimulus signal and the modeled membrane response; (ii) in the suprathreshold regime, the Population Vector and the Spike Field Coherence are employed to estimate phase preferences and the coupling intensity between the input stimulus and the Action Potentials. The results observed are i) in the subthreshold regime the values of the phase differences change with distinct frequencies of an input stimulus; ii) in the supra-threshold regime the preferential phase of Action Potentials changes for different frequencies. In addition, we explore other parameters of the model, such as noise and membrane characteristic-time, in order to understand different types of neurons and extracellular environment related to ephaptic communication. Such results are consistent with results observed in empirical experiments based on ephaptic coupling behavior. In addition, the QIF-E model allows further studies on the physiological importance of ephaptic coupling in the brain, and its simplicity can open a door to simulating ephaptic coupling in neuron networks and evaluating the impact of ephaptic communication in such scenarios.

Spatial and temporal analysis of severe fever with thrombocytopenia syndrome in Zhejiang Province, China, 2011 - 2015

Introduction: Severe fever with thrombocytopenia syndrome (SFTS) is an emerging infectious disease first discovered in northeast and central China in 2009, and SFTS cases increased year by year in China. This study aimed to identify the spatial and temporal clusters of SFTS in Zhejiang Province, China. Methodology: We analyzed the surveillance data of SFTS in Zhejiang Province during 2011 - 2015. Descriptive statistics were used to analyze the general characteristics and overall trend of SFTS. Circular statistic method was utilized to identify the seasonality. Space–time scan analysis was performed to explore the high risk spatio-temporal clusters of SFTS cases at county level. Results: A total of 194 confirmed SFTS cases were reported in Zhejiang Province during 2011 - 2015. We found a significant increase in overall time trend since 2011. The seasonality was statistically significant (P < 0.001), with a mean date (95% CI) of 21st June (12th ~ 30th in June). Totally 21 (23%) counties reported the occurrence of SFTS, which gradually spread throughout Zhejiang. Three spatio-temporal clusters were detected, with one principle cluster (Daishan County, RR 234.48, June 2013 - November 2015) and two secondary clusters (6 counties, RR 30.73, April - October in 2015; Anji County, RR 373.26, May 2014). Conclusions: Our results suggested that SFTS has increased and spatially expanded over the past years, with a remarkable seasonality. Three spatio-temporal clusters were identified. These findings are important for the improvement of SFTS surveillance and control strategies.

COMPORTAMENTO FENOLÓGICO DE Emmotum nitens (Benth.) Miers (METTENIUSACEAE) EM FRAGMENTO DE CERRADÃO

Emmotum nitens é uma espécie bem conhecida em termos de florística e fitossociologia, entretanto, há poucos trabalhos que tratam-se de sua fenologia. Este estudo buscou avaliar a fenologia reprodutiva de uma população de E. nitens no Município de Rio Verde, Goiás. Observou-se mensalmente as fenofases reprodutivas (botão, antese, fruto imaturo e maduro) de 15 indivíduos. Para a coleta dos dados utilizou-se o método de Fournier e presença/ausência, e para analisar os mesmos utilizou-se a estatística circular e correlação com as variáveis meteorológicas (temperatura e precipitação). E. nitens produziu botões e flores de modo irregular ao longo do estudo, no entanto se correlacionaram positivamente com a temperatura. Durante todo estudo registrou-se frutos imaturos, embora as maiores concentrações ocorreram na transição do período seco-chuvoso e durante as chuvas, correlacionando-se positivamente com a precipitação. A maturação dos frutos iniciou-se no final da estação das chuvas, com maiores intensidades no período seco. Para E. nitens é mais vantajoso apresentar reprodução continua já que a mesma não é fortemente limitada pelas variáveis climáticas da área de estudo, do que seguir um padrão sazonal.Palavra-chave: fenologia, espécie de cerrado, eventos reprodutivos, correlação com metereologia. PHENOLOGICAL BEHAVIOR OF EMMOTUM NITENS (BENTH.) MIERS (METTENIUSACEAE) ON CERRADÃO FRAGMENT ABSTRACT:Emmotum nitens is a well-known species in terms of floristic and phytosociology, however, there are few studies that deal with its phenology. The objective of this study was to evaluate the reproductive phenology of a population of E. nitens in the municipality of Rio Verde, Goiás. The reproductive phenomena (flower bud, anthesis, immature fruit and ripe fruit) were observed monthly in 15 individuals. Fournier method and presence/absence were used to collect the data, and to analyze them, the circular statistic and correlation with the meteorological variables (temperature and precipitation) were used. E. nitens produced flower bud and flowers irregularly throughout the study, however they correlated positively with temperature. During the whole study immature fruits were recorded, although the highest concentrations occurred in the transition from the dry-rainy season and during the rains, correlating positively with the precipitation. Fruit maturation began at the end of the rainy season, with higher intensities in the dry season. For E. nitens it is more advantageous to present continuous reproduction since it is not strongly limited by the climatic variables of the study area, rather than following a seasonal pattern.Keywords: phenology, species of cerrado, reproductive events, correlation with meteorology. DOI:

ANALISIS MODEL REGRESI NONPARAMETRIK SIRKULAR-LINEAR BERGANDA

Circular data are data which the value in form of vector is circular data. Statistic analysis that is used in analyzing circular data is circular statistics analysis. In regression analysis, if any of predictor or response variables or both are circular then the regression analysis used is called circular regression analysis. Observation data in circular statistic which use direction and time units usually don’t satisfy all of the parametric assumptions, thus making nonparametric regression as a good solution. Nonparametric regression function estimation is using epanechnikov kernel estimator for the linier variables and von Mises kernel estimator for the circular variable. This study showed that the result of circular analysis by using circular descriptive statistic is better than common statistic. Multiple circular-linier nonparametric regressions with Epanechnikov and von Mises kernel estimator didn’t create estimation model explicitly as parametric regression does, but create estimation from its observation knots instead.

Evaluation of the effect of weather on concentrations of airborne Artemisia pollen using circular statistic

The diurnal pollen pattern of <em>Artemisia </em>seems to be similar in many regions in Central and Eastern Europe, with its highest concentration before noon. This research is a continuation of a preliminary study that was carried out in Rzeszów 10 years ago. The Spearman nonparametric correlation test and the angular-linear correlation were used to verify assumptions about the influence of meteorological parameters on daily and hourly variations of <em>Artemisia </em>pollen concentrations in the atmosphere. The results showed that the patterns of hourly and daily <em>Artemisia </em>pollen concentration in the air of Rzeszów did not differ significantly from the results obtained in previous years, except PI value which was significantly lower. The majority of <em>Artemisia </em>pollen grains appeared in the air before noon and in the early afternoon. However, on some days the peaks occurred around midnight. The hourly and daily <em>Artemisia </em>pollen concentrations were strongly influenced by temperature and relative humidity. Daily concentration was also influenced by radiation and sunshine duration. We do not exclude other factors, such as secondary deposition and long distance transport. We proposed circular statistics as an appropriate method of analysis of the relationship between meteorological parameters and hourly airborne pollen concentration.