Abstract
A model for building a chatbot to automate technical support work was developed, the model was optimized and the developed chatbot was tested. This development will help to reduce the load ...on the existing technical support system and to solve users’ routine tasks without human intervention.
Smith–Purcell radiation is well known as a source of quasi-monochromatic electromagnetic radiation that occurs when fast electrons move above a diffraction grating. In this paper, we calculated the ...Smith–Purcell radiation generation from a flat surface along which there is a field of a standing laser wave. A periodically changing laser field induces a periodic inhomogeneity in the distribution of electrons in the near-surface layer. This periodicity, being an analogue of a diffraction grating, leads to the possibility of generating Smith–Purcell radiation. It is shown that the properties of Smith–Purcell radiation from such an unusual “light” grating are also unusual: the dispersion relation, unlike the standard for Smith–Purcell radiation, does not contain diffraction orders, so that all radiation is concentrated in one peak. The calculated effect makes it possible to control the radiation frequency or angle by changing the laser frequency and may be of interest for the development of new compact radiation sources with tunable characteristics and for non-invasive diagnostics of relativistic electron beams.
In this work, we construct for the first time the theory of small-angle transition radiation from multilayered structures. The theoretically obtained spectral and angular distributions of radiated ...photons are compared with those predicted by Geant4, a very popular package used today for numerical simulation of different physical processes. We demonstrate that, while spectral distributions ideally coincide, the angular ones differ. We argue that transition radiation from the multilayered structure must contain sharp spikes having the interference nature and caused by the effect of merging two maximum frequencies in dispersive media, and thus Geant4 needs improving in this respect. The transition radiation theory developed here for the small-angle case can play a vital part for the possible future Small Angle Spectrometer at the LHC, other experiments of this kind, and detectors for hadrons of the tera-electron-volt energy range.
It has been established that the waters of the transboundary Razdolnaya (Suifen) and Tumannaya (Tumen) Rivers are highly polluted by nutrients. Loads of nutrients supplied by the Razdolnaya and ...Tumannaya Rivers cause eutrophication and induce seasonal hypoxia in areas off the river mouths in the Amursky Bay (northwestern part of Peter the Great bay (PGB)) and the Far Eastern Marine Biosphere Reserve (FEMBR) area (southwestern part of PGB). In both cases, hypoxia developed in the bottom waters in topographic depressions in the basins after the peak nutrient fluxes that occur in summer due to the monsoon climate. In 2013, anoxia occurred in the FEMBR area as a result of unusually heavy atmospheric precipitation at the end of July. The hypoxic areas expanded over approximately 60 km2 and 17 km2 in Amursky Bay and the FEMBR area, respectively. The hypoxia durations were approximately three months in 2011 in the semi-enclosed Amursky Bay and three weeks in 2014 in the more open FEMBR area. The observed hydrochemical anomalies (oxygen, phosphorus, silica, pH, DIC, ammonium) suggest that the main cause of hypoxia is degradation of “excess” diatoms on the water/sediment interface under dynamic water limitation. Mooring observations by a water quality monitoring station registered very high chlorophyll concentrations (approximately 50 mg/m3) in the bottom waters of the FEMBR area. These high chlorophyll concentrations may be attributed to the topographic depression, which works as a sediment trap and accumulates organic matter. Sharply increasing of transparency of water column in the FEMBR area caused by replacement of coastal waters on the waters of open sea can to develop periphyton on seafloor. There is synchronization in deoxygenation of regional water basins (in our case it is the shelf and open part of the Sea of Japan) and global basins (oceans) which may be caused by variations in the chemical composition of atmosphere.
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•It has been established that the waters of the transboundary Razdolnaya (Suifen) and Tumannaya (Tumen) Rivers are highly polluted by nutrients.•Loads of nutrients supplied by two transboundary rivers cause eutrophication and hypoxia events in areas off the river mouths in Peter the Great bay.•In both cases, hypoxia developed in the bottom waters in topographic depressions in the basins after the peak nutrient fluxes that occur in summer. In 2013, anoxia occurred in the FEMBR area due to unusually heavy atmospheric precipitation at the end of July.•There is synchronization in deoxygenation of regional water basins (in our case it is the shelf and open the Sea of Japan) and global basins (oceans) which may be caused by variations in the chemical composition of atmosphere.
This book deals with diffraction radiation, which implies the boundary problems of electromagnetic radiation theory. It presents different analytical models of diffraction radiation and results of ...recent experimental studies.
Currently, in order to decrease the negative effects caused by the presence of a discrete phase in the flow path of steam turbines stages operating in wet-steam area, different technical solutions ...are apply. These methods reduce the number of coarse droplets and wetness of working medium. The implementation of erosion reduction methods requires modifying surfaces of flow path, which can significantly affect the efficiency of the steam turbine. For example application of intrachanel moisture removing and steam injection needs changes of the stator blades surfaces. This article is a part of researches cycle about the efficiency of steam injection on the stator blade surface as the main method of coarse liquid particles diameters reduction in the last stages of high-power steam turbines. The paper presents the results of the analysis and comparison of experimental research unmodified profile to the profile of the stator blade changed by injection slot. The comparison of the profile losses considered blades is present. The analysis of the experimental results showed the feasibility and efficiency of this method of coarse liquid particles diameters reduction in the last stages of high-power steam turbines.
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Content of accumulated carbon (C
dep
, which is referred to as blue carbon, BC) was calculated for the uppermost 1-m thicknesses of sediments in bights of the Peter the Great Bay of the Sea of ...Japan in 2014–2020. In the absence of Zostera Marina (ZM) meadows in Voevoda, Novgorodskaya and Uglovoy bights, BC contents were 140, 99, and 55 tC/ha, respectively. The presence of sea grass significantly increases these values, which were 180 and 126 tC/ha for Voevoda and Novgorodskaya bights, respectively. Using the measured radioactivity of the
137
Cs isotope, the rate of BC accumulation in the bights without meadows ZM was estimated at 17, 69, and 98 gC/(m
2
year) in Uglovoj, Novgorodskaya, and Voevoda bights, respectively, and at 101 and 144 gC/(m
2
year) at sites covered by ZM meadows in Novgorodskaya and Voevoda bights, respectively. Using data of chlorophyll
a
measurements in sediments of the basins in 2018 through 2020, the bioturbation coefficients (62.7–5.3 cm
2
/day) and the constants of apparent organic carbon degradation in sediments (0.003–0.068 day
–1
) were estimated. The maximum BC degradation rates were found in the upper horizons: 550, 39, 6, and 4 gC/(m
2
year) at sites with ZM in Voevoda, and without ZM in Voevoda, Novgorodskaya, and Uglovoy bights, respectively. It was found out that ZM meadows cause the maximum concentration of refractory organic carbon (
in sediments of Voevoda bight).
ExuR and UxuR are paralogous proteins belonging to the GntR family of transcriptional regulators. Both are known to control hexuronic acid metabolism in a variety of Gammaproteobacteria but the ...relative impact of each of them is still unclear. Here, we apply 2D difference electrophoresis followed by mass-spectrometry to characterise the changes in the Escherichia coli proteome in response to a uxuR or exuR deletion. Our data clearly show that the effects are different: deletion of uxuR resulted in strongly enhanced expression of D-mannonate dehydratase UxuA and flagellar protein FliC, and in a reduced amount of outer membrane porin OmpF, while the absence of ExuR did not significantly alter the spectrum of detected proteins. Consequently, the physiological roles of proteins predicted as homologs seem to be far from identical. Effects of uxuR deletion were largely dependent on the cultivation conditions: during growth with glucose, UxuA and FliC were dramatically altered, while during growth with glucuronate, activation of both was not so prominent. During the growth with glucose, maximal activation was detected for FliC. This was further confirmed by expression analysis and physiological tests, thus suggesting the involvement of UxuR in the regulation of bacterial motility and biofilm formation.
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