The paper proposes a quantitative description of the emission properties of fibrous conductive materials (graphite with carbon nanotubes) under the intense electric field. These materials are used as ...cold cathodes in electronic devices; they have a significant effect on the electrical strength of vacuum and gas-filled gaps. The emission current density is theoretically evaluated for cathodes made of carbon nanofiber and those with stochastic parameters of the surface texture. It is shown that the stochastic nanotexture provides the enhanced current emission as compared to that yielded from the theory of the Fowler–Nordheim tunneling process at the similar conditions of the localized enhancement of the external electric field.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Reductions make it possible to reduce the solution of a PDE to solving an ODE. The best known are the traveling wave, self-similar and symmetry reductions. Classical and non-classical symmetries are ...also used to construct reductions, as is the Clarkson–Kruskal direct method. Recently, authors have proposed a method for constructing reductions of PDEs with two independent variables based on the idea of invariance. The proposed method in this work is a modification of the Clarkson–Kruskal direct method and expands the possibilities for its application. The main result of this article consists of a method for constructing reductions that generalizes the previously proposed approach to the case of three independent variables. The proposed method is used to construct reductions of the unsteady axisymmetric boundary layer equation to ODEs and simpler PDEs. All reductions of this equation were obtained.
The participation of DNA methylation processes in the mechanisms of anterograde and retrograde amnesia caused by impaired reconsolidation of conditioned food aversion memory by NMDA glutamate ...receptor antagonists or serotonin receptor antagonists, respectively, were studied on grape snails. Anterograde amnesia was characterized by impaired formation of long-term memory during repeated learning. Administration of a DNA methyltransferase (DNMT) inhibitor to amnestic animals resulted in accelerated formation of long-term memory during 1 day of repetitive training
vs
3 days during initial training. In serotonin-dependent retrograde amnesia, repeated learning without DNMT inhibitor administration or after inhibitor injections led to the formation of long-term memory. The dynamics of memory formation was similar in both cases and did not differ from that during the initial training: the memory was formed within 3 days of training. Thus, epigenetic processes of DNA methylation are selectively involved in the mechanisms of anterograde amnesia, but do not participate in the mechanisms of retrograde amnesia.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
An updated set of goals and objectives for the Mercury Gamma and Neutron Spectrometer (MGNS) are presented based on the most recent findings of the MESSENGER mission. The updated design of MGNS with ...the new CeBr
3
crystal for detection of gamma-ray along with its benefits for the detection of
40
K and K/Th ratio are discussed. MGNS will then be capable of measuring the elemental composition of shallow subsurface in order to empirically evaluate the fittest model on the origin of Mercury, as well as the presence of possible water ice deposits on the permanently shadowed polar craters on the planet. We present the results of the first measurements in space performed during the instrument commissioning phase and during the first Earth flyby which occurred in April 2020.
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DOBA, EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, IZUM, KILJ, KISLJ, MFDPS, NLZOH, NUK, OBVAL, OILJ, PILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UILJ, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
The modern development of the economy of the Russian Federation is characterized by an imbalance in the socio-economic development of the regions, which is due to the increased interregional ...competition, uneven resource provision, investment history, etc. Regions are components of the unified socio-economic and political system of Russia, but each of them has its specifics. Among the factors that determine the specifics of the region stand out: historical, climatic, national, social, and economic. Taking into account all these factors, the choice of means and methods of effective management of the socio-economic system of the region should be made to ensure its sustainable long-term development and functioning. In recent years, under the influence of a qualitatively different level of development of the productive forces, the introduction of innovations in all spheres of life, IT and telecommunication systems, as well as the development of network forms of organizing production, the problem has taken on new forms.
Degradation and restoration of mountain pastures Bekuzarova, S; Kozyrev, S; Kozyrev, A ...
IOP conference series. Earth and environmental science,
10/2020, Volume:
579, Issue:
1
Journal Article
Peer reviewed
Open access
The destructions which occur in the mountain phytocenosis reduce the adaptive capabilities of plant formation, as a result their productivity, longevity and resistance to adverse factors decrease. ...The species previously typical of indigenous communities do not find ecological niches. They are on the verge of extinction. This contributes to the degradation of species composition. Various secondary communities become widespread, the whole complex of existence in which differs from the conditions of indigenous communities. In order to study the state of mountain vegetation, phytocenoses were monitored and assessed, taking into account the presence of leguminous components. Vegetation monitoring was carried with regard to the vertical zonation, where the plant species and their disappearance were determined under the influence of anthropogenic and zoogenic factors. The areas with high degradation were determined, where the amount of plant formation increased and the diversity of valuable grass and bean cultures decreased, depending on anthropogenic factors. It was found that the early spring period nutrition of growing plants with the biological product Nikfan promotes the increase in the fodder mass of plants, ensuring their growth and full development. In our experiments, the doses of the biological product in a concentration of 0.1% were justified, creating favorable conditions for the development and growth rate of crops and beans.
The article shows the modern application of the digital economy in Russia, state participation in the development of the digital economy; a method for solving new problems and risks is proposed as a ...tool for ensuring sustainable development.The possibilities of using the digital economy for the SME sector have been identified. Further development prospects were considered, the main threats to the development of the SME sector were identified in the context of the implementation of the digital economy program.
Intense beams of charged particles serve as a working element in electrophysical devices for a wide range of scientific and practical applications. Mathematical modeling of intense beams leads to the ...solution of a self-consistent nonlinear problem, which includes the calculation of electric and magnetic fields, trajectories of charged particles, and space charge. An extended electron-optical system is understood as an electron-optical system whose size in the direction of the beam’s motion is much larger than the transverse size. The use of traditional computational approaches to modeling such systems did not give satisfactory results. In this paper, we propose new algorithms and technologies aimed at improving their accuracy and reducing the calculation time. They are based on computational domain decomposition methods and are as follows. First, the extended computational domain is divided into two subdomains: in the first subdomain, an intense beam is formed, and in the second subdomain, it is additionally accelerated and transported. The solutions are “stitched” by the alternating Schwarz method. Second, in each of these subdomains, an adaptive quasi-structured locally modified grid is constructed, consisting of structured subgrids. The proposed quasi-structured grid can significantly reduce labor costs when calculating the trajectories of charged particles. Third, on the emitter, the singularity is isolated by introducing a near-emitter subdomain. In this subdomain, an approximate analytical solution is constructed, which is stitched with the numerical solution in the main subdomain in the iterative Broyden process. On the example of a model problem about a flat diode, the fast convergence of the Broyden method is shown. With the help of the proposed algorithms and technologies, the results of modeling a complex practical system are obtained, which closely match the results of natural experiments.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Metamaterials, exhibiting simultaneously negative permittivity epsilon and permeability mu, more commonly referred to as left-handed metamaterials (LHMs) and also known as negative-index materials, ...have received substantial attention in the scientific and engineering communities 1. Most studies of LHMs (and electromagnetic metamaterials in general) have been in the linear regime of wave propagation and have already inspired new types of microwave circuits and devices. The results of these studies have already been the subject of numerous reviews and books.
A
bstract
The cross section of the process
e
+
e
−
→ ηπ
+
π
−
is measured using the data collected with the CMD-3 detector at the VEPP-2000 collider in the center-of-mass energy range from 1
.
1 to 2
....
0 GeV. The decay mode
η → γγ
is used for
η
meson reconstruction in the data sample corresponding to an integrated luminosity of 78
.
3 pb
−
1
. The energy dependence of the
e
+
e
−
→ ηπ
+
π
−
cross section is fitted within the framework of vector meson dominance in order to extract the Γ(
ρ
(1450)
→ e
+
e
−
)
B
(
ρ
(1450)
→ ηπ
+
π
−
) and the Γ(
ρ
(1700)
→ e
+
e
−
)
B
(
ρ
(1700)
→ ηπ
+
π
−
) products. Based on conservation of vector current, the analyzed data are used to test the relationship between the
e
+
e
−
→ ηπ
+
π
−
cross section and the spectral function in
τ
−
→ ηπ
−
π
0
ντ
decay. The
e
+
e
−
→ ηπ
+
π
−
cross section obtained with the CMD-3 detector is in good agreement with the previous measurements.
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