Mutual synchronization and clustering in randomly coupled chaotic dynamical networks

We introduce and study systems of randomly coupled maps (RCM) where the relevant parameter is the degree of connectivity in the system. Global (almost-) synchronized states are found (equivalent to the synchronization observed in globally coupled maps) until a certain critical threshold for the connectivity is reached. We further show that not only the average connectivity, but also the architecture of the couplings is responsible for the cluster structure observed. We analyse the different phases of the system and use various correlation measures in order to detect ordered non-synchronized states. Finally, it is shown that the system displays a dynamical hierarchical clustering which allows the definition of emerging graphs.Comment: 13 pages, to appear in Phys. Rev.

ВОЛЬТАМПЕРОМЕТРИЧЕСКАЯ МУЛЬТИСЕНСОРНАЯ СИСТЕМА НА ОСНОВЕ МОДИФИЦИРОВАННЫХ ПОЛИАРИЛЕНФТАЛИДАМИ СТЕКЛОУГЛЕРОДНЫХ ЭЛЕКТРОДОВ ДЛЯ РАСПОЗНАВАНИЯ И ОПРЕДЕЛЕНИЯ ВАРФАРИНА

Voltammetric sensors and sensory system based on glassy carbon electrodes modified by polyarylenephthalides (chlorinated polyphthalidylidenefluorene, polyphthalidylidene diphenyl and brominated polyphthalidylidene diphenyl) were developed for the recognition and determination of warfarin. The electrochemical and analytical characteristics of the sensors were studied. The optimal conditions for recording voltammograms of warfarin oxidation were established: the range of working potentials was 0.5 ÷ 1.2 V, scan rate was 20 mVs-1, the electrode holding time in the analyzed solution was 30s, and the pH of the supporting electrolyte was 6.86 (Na2HPO4 + KH2PO4). Using the values of the slope of the dependence log ip = log v + const (Δlg ip / Δlg v = 0.7 ÷ 0.9), it was found that the rate-controlling step of warfarin oxidation was the depolarizer adsorption on the surface of the polymer modifier. The linear range of the dependence of the maximum of warfarin oxidation peak on the concentration was 0.3×10-6 ÷ 0.5×10-3 М. Using the “added-found” method, the accuracy of determining the warfarin content in the model solutions was evaluated. The relative standard deviation and relative measurements error didn’t exceed 4.63% and 11.1% respectively. By the means of chemometrics methods (principal components analysis and SIMCA) the possibility of the recognition of warfarin preparations without isolating the active substances in dosage forms was shown, which made it possible to distinguish pharmaceutical preparations from the different manufacturers. At the same time, the sample preparation procedure was significantly simplified, and the cost and time of the analysis were reduced. It was also shown that the use of the multisensory system of the “electronic tongue” type significantly increased the percentage of correctly recognized samples in comparison to the registration of voltammograms on the single sensor. The proportion of correctly recognized samples was 97-100%.Keywords: warfarin, voltammetry, polyarylenephthalide, modified electrodes, sensor system(Russian) DOI: http://dx.doi.org/10.15826/analitika.2019.23.4.003R.A. Zilberg, Yu.A. Yarkaeva, D.I. Dubrovsky, L.R. Zagitova, V.N. MaistrenkoBashkir State University, Department of Chemistry,32, Validy Str., Ufa, 450076, Russian FederationРазработаны вольтамперометрические сенсоры и сенсорная система на основе стеклоуглеродных электродов, модифицированных полиариленфталидами – хлорированными полифталидилиденфлуореном, полифталидилидендифенилом и бромированным полифталидилидендифенилом, для распознавания и определения варфарина. Изучены электрохимические и аналитические характеристики сенсоров. Установлены оптимальные условия регистрации вольтамперограмм варфарина: диапазон рабочих потенциалов 0.5 ÷ 1.2 В, скорость развертки потенциалов 20 мВ/с, время выдерживания электрода в анализируемом растворе 30 с, pH фонового электролита 6.86 (Na2HPO4 + KH2PO4). По  значениям тангенса угла наклона зависимости lg ip = lg v + const (Δlg ip/Δlg v = 0.7÷ 0.9) установлено, что лимитирующей стадией процесса окисления варфарина является преимущественно адсорбция деполяризатора на поверхности полимерного модификатора. Линейный характер зависимости максимального тока окисления варфарина от концентрации сохраняется в диапазоне 0.3·10-6 ÷ 0.5·10-3 М. При определении содержания варфарина в модельных растворах методом «введено-найдено», относительное стандартное отклонение не превышает 4.6 %, относительная погрешность не превышает 11.1 %. С использованием методов хемометрики: метода главных компонент (МГК) и метода формального независимого моделирования аналогий классов (SIMCA) показана возможность распознавания препаратов варфарина без выделения действующих веществ в лекарственных формах, что позволяет различать лекарственные средства различных производителей. При этом заметно упрощается процедура пробоподготовки, снижаются стоимость и время анализа. Показано, что использование мультисенсорной системы типа «электронный язык» существенно повышает процент правильно распознанных образцов по сравнению с регистрацией вольтамперограмм на одном сенсоре. Доля правильно распознанных образцов составляет 97-100 %.Ключевые слова: варфарин, вольтамперометрия, полиариленфталид, модифицированные электроды, сенсорная системаDOI: http://dx.doi.org/10.15826/analitika.2019.23.4.00

Differential diagnosis of primary and metastatic ovarian carcinomas

Ovarian tumors constitute 3.4 % of the structure of oncological diseases in women worldwide. However, the ovaries are also a common target for metastasis of carcinoma from other organs. Conducting differential diagnosis between primary carcinoma and metastasis is often challenging. The aim of this study is to highlight the issues of morphological and immunohistochemical differential diagnosis of primary ovarian carcinomas and metastases from carcinomas of various organs to the ovaries. Materials and methods. Data analysis of clinical and pathohistological studies of 381 patients. Paraffin sections for pathohistological studies were stained with hematoxylin and eosin using standard methodology. Immunohistochemical studies were conducted in 161 cases using a panel of antibodies: cytokeratins, estrogen receptors, progesterone receptors, CA125, TTF1, Vimentin, CDX2, Villin, Chromogranin A, Synaptophysin, CD56, GATA, p53, Inhibin A, FOXL-2, PAX-8, Ki-67. The specimens were examined and analyzed using the Axioskop 40 microscope (Zeiss) with the AxioCam MRc camera (Zeiss). Results. The article discusses key issues of differential diagnosis of primary and metastatic ovarian carcinomas based on a large clinical and operational material. The application of an adequate panel of immunohistochemical antibodies for verification is considered. The results of the frequency of occurrence of different histological variants of ovarian carcinomas and metastases to the ovaries from carcinomas of other organs are provided based on our own research from 2019 to 2023. The main morphological and immunohistochemical indicators for practical use in the work of a pathologist in the verification of ovarian tumors are presented. An example of forming an antibody panel, taking into account clinical and morphological indicators in a specific clinical case from our own practice, is given. Conclusions. Metastases of carcinomas from other organs to the ovaries constitute half of all cases requiring immunohistochemical investigation based on morphological structure. The most common are metastases from breast and colorectal cancers. However, the diagnosis of metastatic intestinal carcinoma is particularly challenging, as there is usually no clear clinical picture. In the differential diagnosis of primary and metastatic ovarian tumors, a comprehensive approach to analyzing the clinical presentation, microscopic structure of the tumor, and the surrounding tissue plays a significant role. Additionally, the formation of an antibody panel, taking into account these data, is crucial. The article provides a list of antibodies that have demonstrated greater effectiveness in our work