396 research outputs found
Non-LTE abundances of zinc in different spectral type stars and the Galactic [Zn/Fe] trend based on quantum-mechanical data on inelastic processes in zinc-hydrogen collisions
We present a new model atom of Zn I-II based on the most up-to-date
photoionisation cross-sections, electron-impact excitation rates, and rate
coefficients for the Zn I + H I and Zn II + H- collisions. The latter were
calculated using the multi-channel quantum asymptotic treatment based on the
Born-Oppenheimer approach. Non-LTE analysis was performed for the first time
for lines of Zn I and Zn II in the ultraviolet (UV) spectra of two very
metal-poor reference stars, HD 84937 and HD 140283. We found consistent non-LTE
abundance from the resonance Zn I 2138 A line, the subordinate lines, and the
lines of Zn II. In both stars, non-LTE leads to 0.17 dex higher average
abundance from Zn I, while, for Zn II lines, non-LTE corrections are minor and
do not exceed 0.06 dex. Using lines of Zn I in the high-resolution spectra, we
determined the non-LTE abundances for a sample of 80 stars in the -2.5 < [Fe/H]
< 0.2 metallicity range. The [Zn/Fe] versus [Fe/H] diagram reveals a dip, with
[Zn/Fe] = 0.3 in the most metal-poor stars, a close-to-solar value for [Fe/H] =
-1.2, and increasing [Zn/Fe] up to 0.3 in the thick disk stars. The
close-to-solar metallicity stars have subsolar [Zn/H] = -0.1, on average.
Non-LTE abundances of zinc were derived for the first time for seven reference
F to B-type stars. We provide a grid of the non-LTE abundance corrections.Comment: 15 pages, 9 figures, accepted to MNRA
Evolution of the texture of low-carbon microalloyed pipe steel in the seamless pipe manufacturing process
A method of orientation microscopy (with the application of the EBSD technique) is used in investigation of the microstructure and texture in steel 0.08 % C-Cr-Mo-V formed at different stages of the seamless pipe manufacturing process, namely, after hot finishing and after full quenching with subsequent high-temperature tempering. It is shown that, at the final stage of hot finishing followed by heat treatment, the texture is represented by four scattered orientations. The found texture inheritance in the investigated material is presumably related to reproduction of special circa Σ3 boundaries between crystal grains at each phase transition. © 2016 Author(s)
X-ray film chamber with carbon target of Tien-Shan complex array
X-ray films were exposed inside the ionization calorimeter under 74g/sq cm of carbon and 5 cm of lead. The X-ray film chamber area is 35 sq. m. Moving X-ray films were used, 50% of the events, which succeeded to determine incidence time, were identified with corresponding extensive air showers (EAS). For such events the size spectrum of associated EAS was derived. Two methods of energy measurement using X-ray films and ionization calorimeter were compared. The energy transfer from selected hadron to electromagnetic component is illustrated. It is found that in cascades with high energy release into electromagnetic components the hadron component is practically absent
Project approach to the development of rural tourism
The authors of the article provide an overview of scientific approaches to the definition of the essence and role of event and gastronomic tourism against the backdrop of the rural tourism promotion currently carried out. The interrelation between all the aforementioned types of tourism and the expediency of their joint development are substantiated. The necessity of holding events in order to smooth out the seasonality of rural tourism and attract tourists interested not only in standard services of rural guest houses but also in entertainment events is proved. Special emphasis is placed on the application of the project approach to the process of creating events. A description of the festivals held in the Vologda region is provided. The main problems of the implementation of project management at the municipal level are identified. The possibility of holding gastronomic festivals within the clusters operating in the region is considered. The example of the «SyrFest» gastronomic festival is used to demonstrate a possible project structure designed for such event
Diffuse Neuroendocrine System: Structural and Functional Effects of Radiation Injury to Amine Precursor Uptake and Decarboxylation (APUD) Cells
The paper presents a review of the results obtained by the authors on the study of external (gamma) and internal (I-131) radiation effects on the functional morphology and linkage of the diffuse neuroendocrine system (DNES) and amine precursor uptake and decarboxylation (APUD) cells of the stomach and duodenum. The investigations performed enabled us to determine that the morphological changes noted in APUD cells had a dose and time dependency. The present study supports the point of view that the radiation initiates serotonin release from APUD cells, which appears to initiate the mechanism of early postirradiation dysfunctions of the gastrointestinal tract and the subsequent adaptive response of DNES. Analysis of our results, together with a review of the literature, indicates that APUD cells actively participate both in pathogenesis of radiation injury and development of organ and tissue radiosensitivity
Cryptic Diversity in Paramecium multimicronucleatum Revealed with a Polyphasic Approach
Paramecium (Ciliophora) systematics is well studied, and about twenty morphological species have been described. The morphological species may include several genetic species. How-ever, molecular phylogenetic analyses revealed that the species diversity within Paramecium could be even higher and has raised a problem of cryptic species whose statuses remain uncertain. In the present study, we provide the morphological and molecular characterization of two novel Paramecium species. While Paramecium lynni n. sp., although morphologically similar to P. multimicronucleatum, is phylogenetically well separated from all other Paramecium species, Paramecium fokini n. sp. appears to be a cryptic sister species to P. multimicronucleatum. The latter two species can be distinguished only by molecular methods. The number and structure of micronuclei, traditionally utilized to discriminate species in Paramecium, vary not only between but also within each of the three studied species and, thus, cannot be considered a reliable feature for species identification. The geographic distribution of the P. multimicronucleatum and P. fokini n. sp. strains do not show defined patterns, still leaving space for a role of the geographic factor in initial speciation in Paramecium. Future findings of new Paramecium species can be predicted from the molecular data, while morphological characteristics appear to be unstable and overlapping at least in some species
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