[Comparative analysis of methods for estimation of undirected coupling from time series of intracranial EEGs of cortex of rats-genetic models of absence epilepsy]

Item does not contain fulltextStudying coupling between brain areas from its electromagnetic activity is one of the key approaches in epilepsy research now, since epileptic activity has been considered to be a result of pathological synchronization in the brain. Often, research is conducted on animal models, because this allows to perform intracranial measurement, and to get rid of interference caused by the skull and to receive signals from deeper regions of the brain such as thalamus or hippocampus. In this study, the intracranial recordings from the frontal and parietal areas of cortex are investigated with a nonlinear correlation coefficient and a mutual information function in a sliding time window. The coupling estimates obtained were subjected for statistical analysis for significance using surrogate data. The dynamics of connectivity between the frontal cortex and the parietal cortex was shown to vary from seizure to seizure and from animal to animal. Therefore, estimates of the significant change in connectivity associated with initiation of the absense seizure, found previously based on averaging over a large number of animals and a large number of seizures for an each animal, can be a result of contribution of a relatively small number of seizures (less than a half of considered), for which the changes are significant.10 p

X-ray spectral analysis of sintered products made of electroerosive materials obtained from X17 alloy waste in lighting kerosene

The article presents the results of a study of the elemental composition of sintered products from alloy X17 electroerosive materials obtained in lighting kerosene. It is shown that the main elements on the surface of sintered products are chromium, iron and nickel

Shape and morphology of the particles surface of electroerosive powders of micro- and nanometric fractions, obtained from H17MYuA steel in kerosene

One of the main directions of engineering technology development at present is the improvement of existing and the development of new waste-free, environmentally friendly, material-saving production processes. Powder metallurgy is a branch of technology, including the manufacture of powders from metals and their alloys and the preparation of blanks and products from them without melting the main component. In most cases, new materials are created in order to provide the optimal combination of product price and operational characteristics. Chromium is the most common alloying element. Steel alloyed with chromium has increased strength, hardness, wear resistance, resistance to corrosion in aggressive and oxidizing environments. The presence of chromium increases the hardenability of steel. The process of obtaining powder materials by the method of electroerosive dispersion compares favorably with the possibility of producing powders even from particularly hard and refractory materials. In the case of grinding material by this method, the only important criterion is the electrical conductivity of the material being ground. Worn parts and other scrap can be used as feedstock during the process. The purpose of the study is to investigate the powder obtained from the waste of chromium-containing steels. Thanks to the study of the used powder samples on modern devices, results were obtained, which indicate that the chromium-containing powder, obtained by electroerosive dispersion, can be reused in the restoration and hardening of machine parts

X-ray spectral analysis of sintered products made of electroerosive materials obtained from X17 alloy waste in lighting kerosene

The article presents the results of a study of the elemental composition of sintered products from alloy X17 electroerosive materials obtained in lighting kerosene. It is shown that the main elements on the surface of sintered products are chromium, iron and nickel

Detecting best lag of embedding for modeling spike-wave discharges from experimental data

Item does not contain fulltextPurpose. Optimal value of the embedding lag calculation is made. Lag is one of empirical parameters of mathematical models, used in autoregressive models for prediction, coupling analysis, signal classification etc. Methods. The first minimum in the dependence of the mutual information function on the time lag was detected. Results. The calculation showed that the optimal lag is about 8 sampling intervals (1/64 s or 1/8 of the characteristic oscillation period for the absence seizures). Discussion. The optimal lag is about 1/8 of the characteristic oscillation period was obtained for both epileptiform and background activity, including preictal and different stages of ictal activity, i. e. this time scale is present in the signal throughout the observation time.The 23nd Annual Conference Saratov Fall Meeting 2019 VII Symposium on Optics & Biophotonics (Saratov, Russia, September 23-27, 2019

CVD niobium in Nb-Hal-(H)-inert gas systems : A thermodynamic and experimental approaches

The thermodynamic analysis of the niobium CVD in Nb-Hal-(H)-inert gas (Hal = l, Cl) systems has been performed with using the method of minimization of the Gibbs' free energy for the wide region of conditions. The results of the thermodynamic calculations allow to select the Nb-I-inert gas system as the more preferable hydrogen free system. The experimental niobium CVD data in the Nb-Cl-H-inert gas system were analyzed with thermodynamic view. The calculations and experimental results show a good agreement

Connectivity detection in application to spike-wave discharge study

Contains fulltext : 227417.pdf (publisher's version ) (Open Access)In our study, we compare three popular approaches to directed coupling analysis, in particular transfer entropy and two types of Granger causality, applied to real data from genetic absence epilepsy rats. We have chosen the channels for which the coupling architecture is already well known from previous studies. Recordings from 5 WAG/Rij rats of 8 hours duration with at least 28 spontaneous seizures of length not less than 6 s in each recording were studied. To test results for significance, surrogate signals based on series permutation technique were constructed. Connectivity development in time was investigated by considering six two-second intervals before, during and after the seizure. Our outcomes showed large differences between studied approaches, while all of them exploit the same general idea. Transfer entropy demonstrated the smallest number of significant couplings throughout all three considered measures, while the linear Granger causality showed the largest number of them. This indicates that transfer entropy is the most conservative measure and the least sensitive one. Its sensitivity is affected by insufficient series length. The linear Granger causality is likely to demonstrate insufficient specificity.12 p