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1

Subfossil freshwater bivalve mollusk shells present data on stratigraphy of Dniester and Prut riverine deposits

Автор: Lyubas

The article provides information on the outcrops of the Neogene-Quaternary riverine sediments of the North-Western Black Sea coastal area. A description of five outcrops of fluvial deposits located on the territory of the modern basins of the Dniester and Prut rivers is given. Based on the granulometric composition of the sediments and the presence in them of the fossil shells of freshwater bivalve mollusks (Bivalvia: Unionoida), an assumption has been made about the characteristics of the ancient river ecosystems of the Dniester and Prut on different Pliocene and Pleistocene time sections. A review of the data in the body of literature on the geological age of the studied outcrops was undertaken. The localities considered provide information on the sedimentation conditions in this region from the Pliocene to the Late Pleistocene. Previously, various approaches were used for dating such rocks and for determining the stratigraphic position of fossil material found in them. The article considers the method of amino acids racemization as one of the approaches. Racemization allows to obtain new data on the stratigraphy of Neogene-Quaternary riverine sediments and to solve the problem of their dating. The sampling principles of carbonate material for the analysis of amino acids from the mollusk shells and features of sample preparation are described. Five amino acids were used: aspartic acid (Asp), glutamic acid (Glu), leucine (Leu), phenylalanine (Phe) and isoleucine (Ile). The D/L ratios were analyzed (amino acid racemization (or AAR) is the interconversion of amino acids from one chiral form (the L – (laevo) amino acids which are the building blocks of proteins) to a mixture of L- and D- (dextro) forms. The extent of racemization is measured by the ratio of D/L isomers (it increases as a function of time and temperature and can be used for geochronology) from the same group of fossils (genera), which were preserved under similar environmental conditions, inorganic geochemistry and thermal histories. Based on the obtained values, it can be concluded that the analysis of the racemization of amino acids is useful for determining the geological age of fossil shells of freshwater bivalve mollusks, but there are limitations regarding age. In the shells of the Pliocene sites, the values of some amino acids are close to one, indicating that the racemization took place. D/L values in shells from Pleistocene localities allowed the determination of their stratigraphic position.

2

State of spring phytoplankton and quality of the Kenozero waters in 2018

Автор: Otchenash

Phytoplankton constitutes a key part of all aquatic ecosystems. It produces organic matter, thus forming the first level of food chains in water bodies. In addition, phytoplankton plays a major role in the water quality formation. The studies of algocoenosis always remain relevant, since the obtained data provides important information on the ecological status of water bodies. This information can subsequently be used for planning and implementing environmental measures, which are particularly significant for water bodies located in specially protected areas. National parks existing for the purposes of nature preservation, education and research are also designed for tourism, which makes their ecosystems more vulnerable. Population residing in such territories and its economic activity may also carry some environmental risks, which necessitates regular complex observations. This paper covers the state of spring phytoplankton community of Lake Kenozero in 2018, its qualitative and quantitative characteristics (species composition, abundance and biomass). In the course of research, we identified 70 phytoplankton taxa belonging to seven divisions: Bacillariophyta, Dinophyta, Chlorophyta, Cyanophyta, Chrysophyta, Xanthophyta and Euglenophyta. The dominant species complex included diatoms (Asterionella formosa, Melosira granulata, Tabellaria fenestrata), representatives of Dinophyta (Gymnodinium sp.), as well as small euglenoids. Species diversity was estimated using the Shannon-Weaver index. Aquatic environment contamination was assessed, i.e. the saprobity index was calculated and the class of surface water quality was determined. According to the water quality classification of water bodies and watercourses by hydrobiological indicators, Lake Kenozero was assigned the second class of water quality (moderately polluted).

3

State of spring phytoplankton and quality of the Kenozero waters in 2018

Автор: Otchenash

Phytoplankton constitutes a key part of all aquatic ecosystems. It produces organic matter, thus forming the first level of food chains in water bodies. In addition, phytoplankton plays a major role in the water quality formation. The studies of algocoenosis always remain relevant, since the obtained data provides important information on the ecological status of water bodies. This information can subsequently be used for planning and implementing environmental measures, which are particularly significant for water bodies located in specially protected areas. National parks existing for the purposes of nature preservation, education and research are also designed for tourism, which makes their ecosystems more vulnerable. Population residing in such territories and its economic activity may also carry some environmental risks, which necessitates regular complex observations. This paper covers the state of spring phytoplankton community of Lake Kenozero in 2018, its qualitative and quantitative characteristics (species composition, abundance and biomass). In the course of research, we identified 70 phytoplankton taxa belonging to seven divisions: Bacillariophyta, Dinophyta, Chlorophyta, Cyanophyta, Chrysophyta, Xanthophyta and Euglenophyta. The dominant species complex included diatoms (Asterionella formosa, Melosira granulata, Tabellaria fenestrata), representatives of Dinophyta (Gymnodinium sp.), as well as small euglenoids. Species diversity was estimated using the Shannon-Weaver index. Aquatic environment contamination was assessed, i.e. the saprobity index was calculated and the class of surface water quality was determined. According to the water quality classification of water bodies and watercourses by hydrobiological indicators, Lake Kenozero was assigned the second class of water quality (moderately polluted). Citation: Otchenash NG, Dvoryankin GA, Imant EN (2019) State of spring phytoplankton and quality of the Kenozero waters in 2018. Arctic Environmental Research 19(1): 43–48. https://doi.org/10.3897/issn2541-8416.2019.19.1.43

4

Spatial distribution of natural and anthropogenic radionuclides in the soils of Naryan-Mar

Автор: Kriauciunas

The objective of the research is to identify the main patterns of spatial distribution of natural and anthropogenic radionuclides (RN) in Naryan-Mar. Urban soils are formed by means of natural soil transformation with the participation of technogenic sedimentogenesis, which leads to disturbance of natural RN migration processes and contributes to the complex structure of natural and anthropogenic RNs contamination of tundra soils. The specific activity of anthropogenic (134Cs, 137Cs) and natural (226Ra, 232Th, 40K) RNs in Naryan-Mar soil was determined. The local low-intensity anomalies (LLIA) of anthropogenic RNs result from transboundary transfer; 134Cs and 137Cs are concentrated in soils with a well-shaped vegetable layer. 226Ra and 232Th LLIAs are confined to regions with stone buildings. 40K LLIAs are conditioned by high density of grassland vegetation involving 40K in the biological cycle. The statistical manipulation of the acquired data involved correlation and factor analysis techniques. The statistical analysis demonstrated a moderate and salient correlation between the content of 232Th and 40K in the soils of the areas built up with wooden houses and the soils of the recreation area, respectively. There is a salient correlation between the content of 134Cs and 40K as well as between 134Cs and 232Th in the soils of the recreation area. The area occupied by technological buildings demonstrates salient and high negative correlations between the content of 226Ra and radionuclides of 40K and 234Th. The multidirectional nature of the 226Ra and 232Th accumulation processes can be explained by their different mobility in the environment. A factor analysis of the specific activities of the radionuclides in the soils (based on the varimax method) revealed that the strongest factor (28%) conjointly regulates the 134Cs and 40K content, which testifies to their affiliation to non-mobile cationogenic elements. The second factor (25%) identified through an analysis of the overall data array may signify that organic matter plays a major role in the 137Cs retention.

5

Semigroups Approximation with Respect to Some Ad Hoc Predicates

Автор: Dang

The problem of semigroups approximation with respect to various predicates has been investigated by many scientists. Some necessary and sufficient conditions for the semigroups approximation with respect to such predicates as “equality”, “membership of an element to a subsemigroup”, “regular conjugation relation”, “Green ratio of L-, R-, H- and D-equivalence”, “membership of an element to a monogenic subsemigroup”, etc. were obtained. However, there were practically no results on the conditions of approximation with respect to the predicate of membership of an element to a subgroup of a given semigroup. The paper presents the necessary and sufficient condition for approximation with respect to this predicate. We constructed a special semigroup acting the role of a minimal approximation semigroup for many predicates. This semigroup has neither identity nor additive identity. It contains an infinite number of idempotents, and the presence of each idempotent is mandatory. By this semigroup, we have successfully solved the problem of approximation with respect to the predicate of membership of an element to a subsemigroup. A class of semigroups is also described, for which it is the minimal approximation semigroup. We obtained a criterion for the approximation of a semigroup with respect to the Green H-equivalence. The problem of algebraic systems approximating with respect to a predicate consists of three components: a set of algebraic systems (groups, semigroups, etc.); set of predicates; set of functions (homomorphisms, continuous mappings, etc.). The change of one of these components determines a new line of research.

6

Solving the Hysteresis Loop Calculation Problem for Josephson Junction Stacks

Автор: Serdyukova

A detailed investigation of the IVC breakpoint and the breakpoint region width gives important information concerning the peculiarities of stacks with a finite number of intrinsic Josephson junctions. The current-voltage characteristics for a stack of n Josephson junctions is defined from solving the system of n nonlinear differential equations. The current voltage characteristic has the shape of a hysteresis loop. On the back branch of the Hysteresis loop, near the breakpoint Ib, voltage V (I) decreases to zero rapidly. The goal of this work is to accelerate the computation of IVC based on numerical solution of the system. A numericalanalytical method was proposed in. This method showed perfect results in IVC calculations for a stack of 9 and 19 intrinsic Josephson junctions and the computation time reduced by five times approximately. The question of choosing a change-over point from “analytical” to numerical calculation was open. In testing computations the change-over point was taken equal to 2Ib. In the case of periodic boundary conditions an equation, determining the approximate location of Ib, was obtained. This moment we succeeded to develop an algorithm determining the approximate value Ib in more complicated technically case of non-periodic boundary conditions with γ = 1. All calculations were performed using the REDUCE 3.8 system.

7

Scilab в математических расчетах

Изд-во ОГТИ

В методических рекомендациях предложен комплекс лабораторных работ для ознакомления с возможностями интегрированной среды Scilab и индивидуальные задания для выполнения.

Предпросмотр: Scilab в математических расчетах.pdf (0,6 Мб)
8

Second Yaroslavl Summer School on Discrete and Computational Geometry. July-August, 2013

ЯрГУ

This book is the second in the series. It contains lecture notes of the Second Yaroslavl Summer School on Discrete and Computational Geometry that took place in July and August of 2013. We hope this volume will be useful to all students and post graduates interested in the state-of-the-art in this field. Funded by Russian Government Grant 220 Contract 11.G34.31.0053

Предпросмотр: Second Yaroslavl Summer School on Discrete and Computational Geometry. July-August, 2013. Lecture Notes.pdf (0,3 Мб)
9

S-амиды сульфосалициловой кислоты как новые люминесцентные реагенты на тербий

Автор: Алакаева
ПРОМЕДИА: М.

Путем синтеза получены S-амиды сульфосалициловой кислоты, которые дают яркие люминесцентные реакции с ионами тербия. Подобраны оптимальные условия комплексообразования и предложены высокочувствительные методы определения тербия.

10

SiC

Автор: Титков
ПРОМЕДИА: М.

Как производят и где применяют кристаллы карбида кремния.

11

Simulink 5/6/7: Самоучитель

Автор: Дьяконов В. П.
ДМК-Пресс: М.

Самоучитель по новейшим реализациям пакета визуального блочного имитационного моделирования Simulink 5/6/7 матричной системы MATLAB R2006/2007. Подробно описаны библиотека блоков Simulink, методика подготовки диаграмм моделей, их редактирование, настройка и запуск на исполнение. Дано описание наиболее важных пакетов расширения Simulink инструментального ящика Blockset, в том числе SimPowerSystems, SimMechanics, Aerospace, Stateflow, Signal Processing, Telecommunication, Video and Image Processing и др. Отражены средства виртуальной реальности. Описаны сотни наглядных примеров применения этих средств.

Предпросмотр: Simulink 567 Самоучитель.pdf (2,6 Мб)