Suchergebnisse

Neurons encode and transmit information in spike sequences. However, despite the effort devoted to understand the encoding and trans-mission of information, the mechanisms underlying the neuronal encoding are not yet fully understood. Here, we use a nonlinear methodof time-series analysis (known as ordinal analysis) to compare the statistics of spike sequences generated by applying an input signal to theneuronal model of Morris–Lecar. In particular, we consider two different regimes for the neurons which lead to two classes of excitability:class I, where the frequency-current curve is continuous and class II, where the frequency-current curve is discontinuous. By applying ordinalanalysis to sequences of inter-spike-intervals (ISIs) our goals are (1) to investigate if different neuron types can generate spike sequences whichhave similar symbolic properties; (2) to get deeper understanding on the effects that electrical (diffusive) and excitatory chemical (i.e., exci-tatory synapse) couplings have; and (3) to compare, when a small-amplitude periodic signal is applied to one of the neurons, how the signalfeatures (amplitude and frequency) are encoded and transmitted in the generated ISI sequences for both class I and class II type neurons andelectrical or chemical couplings. We find that depending on the frequency, specific combinations of neuron/class and coupling-type allow amore effective encoding, or a more effective transmission of the signal. ; C.E. and C.R.M. acknowledge the Spanish State ResearchAgency, through the María de Maeztu Program for Units of Excel-lence in R & D (No. MDM-2017-0711). C.E. is funded by theConselleria d'Innovació, Recerca i Turisme of the Government ofthe Balearic Islands and the European Social Fund with Grant CodeNo. FPI/1900/2016. M.M. and C.M. acknowledge support from theSpanish Ministerio de Ciencia, Innovación y Universidades (No.PGC2018-099443-B-I00) and ICREA ACADEMIA, Generalitat deCatalunya. The authors also acknowledge the Ibersinc networkfunded by Spanish MINECO grant FIS2015-71929-RED ; Peer Reviewed ; Postprint (author's final draft)

AbstractThe characterization of historical mine tailings provides important information for land-management decisions, in particular when considering potential reprocessing activities or the development of an environmental protection program. In addition, outcomes from such characterization may define the scope for a more detailed investigation. The present work describes the characterization of the waste material from the Cabeço do Pião tailings impoundment performed within the project ReMinE: Improve Resource Efficiency and Minimize Environmental Footprint. The purpose of the work was to investigate alternative mine waste management options such as the extraction of valuable resources from an environmental liability. The study involved the collection of 41 samples at different locations at two different depths, physical and chemical characterization of the wastes, natural leaching tests, and potential for acid generation. The results showed that, apart from the potential instability of the dyke (with an average slope of 35°), the drained solutions flowing by percolation contain very small particles with high arsenic contents that are being incorporated into the river sediments. In addition, these very fine-grained materials are available for the transport by the wind creating secondary sources of environmental contamination. This data is fundamental for economic and environmental assessment of the two main alternatives, reprocessing or removal.