This paper presents general characteristics of the ichthyofauna of the Pechora River basin. Based on the results of ichthyological surveys in 1994–2018, as well as published and archived data, the ...current composition of the fish fauna, including the invasive species, is presented. The species diversity and taxonomic status of fishes and their place in various faunistic complexes are also considered in the study. In the ecological aspect, it is determined which ecological groups—differing in characteristics of feeding and natural reproduction (the nature of the spawning substrate, methods of laying eggs, and spawning periods)—the fish belong to. This research touches on the economic significance of the ichthyofauna and identifies rare and innumerous species of fish found in regional Red Data books.
A model of a neural-network-like quantum-mechanical system is considered. The role of neurons is played by quantum-mechanical particles which evolve under the action of an external double-well ...potential. An instanton is used as a spike. Neurons are connected by the interaction potential
. The connection is directional owing to asymmetry of the interaction potential. Therefore, the complete Hamiltonian of the system is
. The system is investigated by the path integral Monte Carlo (PIMC) method. It is shown that with a certain choice of parameters in this system it is possible to transfer activity in long chains of neurons.
The results of studying the effect of hot carrier degradation on the electrical characteristics of high-power laterally diffused metal oxide semiconductor (LDMOS) transistors made according to the ...silicon-on-insulator (SOI) technology, with a long drift region with topological norms of 0.5 microns, are discussed. The analysis of the degradation of hot carriers in high electric fields is based on the experimental results and the additional use of an analytical model. The physical origin of this mechanism is related to the formation of traps at the Si/SiO
2
interface. With the help of numerical analysis and experiments, the electrical characteristics of SOI nLDMOS transistors are considered in a wide range of control voltages in order to study their effect on the safe operation zone and reliability of the device under conditions of the degradation of hot carriers. The results of these studies allow us to conclude that a 20% expansion of the safe operation zone is possible.
The species composition and taxonomic diversity of the Solovetsky Archipelago freshwater ichthyofauna have been revealed. A description of the current state of the fish is provided. The attribution ...of fish to different freshwater faunistic complexes and ecological groups (feeding patterns and mode of natural reproduction) has been considered. Currently, 14 fish species are recorded in the inland waters of the Solovetsky Islands, including local and alien species with varying degrees of acclimatization effect. The possible annual catch of freshwater fish which could be considered optimal has been evaluated. If it is necessary to organize freshwater aquaculture, lacustrine ranching of the whitefish complex in the lakes of the Solovetsky Archipelago seems to be promising. This type of aquaculture is based on the collection and fertilization of eggs at temporary fish breeding stations, its subsequent incubation at fish farms, and the release of reared juveniles into feeding lakes.
Data have been presented on the morphobiological parameters of the anadromous Arctic lamprey Lethenteron camtschaticum (Tilesius, 1811) in spawning stocks of large river basins of the Arkhangelsk ...region – Onega, Severodvinsk and Mezen. The clinal variability of linear-weight parameters, absolute fecundity, and a number of plastic characters was revealed, according to which the lamprey population from the Northern Dvina River occupies an intermediate position between the lampreys of the Onega and Mezen rivers. Higher average values of biological indicators (length, body weight, fecundity) were noted in European lamprey populations compared to those in individuals from the Far Eastern part of the range.
—The long-term dynamics of the taxonomic composition of zooplankton in the lower reaches of the Northern Dvina River and the effect of some hydrochemical factors on its abundance have been studied. ...It is found that the species list of the zooplankton has included 141 species over 50 years: it consisted of a total of 98 taxa in 1965 and 104 taxa in 2012–2019. The results of analyzing the spatiotemporal abundance distribution of the zooplankton and its taxonomic groups are presented. A significant increase in abundance (on account of copepods) and changes in the taxonomic structure of zooplankton have been revealed in the lower parts of the study water area. In 2019, changes in the structure-forming complex of zooplankton were noted for the first time over the study period. It is found that species diversity reaches high values in waters classified as “heavily polluted” and “dirty,” which is evidence for a complex structure of zooplankton communities. The main factor influencing the horizontal distribution of the zooplankton abundance is the dissolved oxygen content of water.
The general characteristics of ichthyofauna from the Northern Dvina River are obtained. Based on the results of ichthyological surveys in 1984–2012, as well as bibliographical and archival data, the ...present composition of the fish community is presented with an accounting of introduced and self-colonized species. The taxonomic status of fish and their belonging to various faunal complexes is considered. In the ecological aspect, the belonging of fish to different ecological groups differing in the feeding and natural reproduction (spawning substrate, methods of spawning, and spawning periods) is distinguished.
Plankton communities are very important for the functioning of aquatic ecosystems 1, 2. Phytoplankton is the dominant primary producer in the aquatic environment, from which most food webs begin, and ...which produces oxygen necessary for aquatic organisms 3. Indicators of phytoplankton development are used to assess the ecological state of water bodies 4. By quickly responding to changes in the aquatic environment, phytoplankton can serve as an indicator of the state of the entire ecosystem.
Objective
—A comparative analysis of the state of phytoplankton in two lakes experiencing anthropogenic pressure and located on the island territory of the Solovetsky archipelago and on the mainland of the Arkhangelsk oblast in the Northern Dvina River basin. Lake Bannoe (Gagarye) is located on the territory of Solovetsky village. Previously, a leather processing plant and a bathing facility of the monastery were located on its shore. Now there are buildings of the Solovetsky branch of the Arkhangelsk experimental algae plant. Lake Kholmovskoye is located in the Primorsky district of the Arkhangelsk oblast, 18 km from the city of Arkhangelsk. On the western shore of the lake is the village of Kholm and summer cottages. From the side of Lake Kholmovskoye, the village of Kholm is surrounded by an artificially dug ditch, into which all household drains flow. On the northern shore are former household premises. An operating cage trout farm is located in the water area of the lake, which is a source of additional organic matter entering the lake waters.
PDF
