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280 results on '"Ovchinnikova O"'

1. Theoretical aspects of human capital influence on regional development

Author

Kokuytseva T. and Ovchinnikova O.

Subjects
Environmental sciences, GE1-350
Abstract

This article is to discuss the state of scholarly research on the influence of human capital on the economic growth and the development of regions. We hereby review the relevant literature published over the past 30 years, and we integrate the various trends and factors into a preliminary and multi-dimensional framework of human capital development. Through this methodologically systematic review and framework development, we provide a more comprehensive and deeper understanding of the connection between human capital development, world technological trends and economic growth. In so doing, we consequently identify various research gaps and prescribe effective ways for future works in this research stream. Conclusively, we discuss the problem of a lack of the demand for human capital (as well as knowledge) in Russian regions that is the main reason for weak economic situation in them. Here is suggested to restructure current regional economy in order to consolidate high qualified human capital in regions and stipulate economic growth in regions.

Published
2020
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10. Thermal Contrast in Nanoscale Infrared Spectroscopy (AFM-IR): Low Frequency Limit

Author

Morozovska, Anna N., Eliseev, Eugene A., Borodinov, N., Ovchinnikova, O., Morozovsky, Nicholas V., and Kalinin, Sergei V.

Subjects
Condensed Matter - Materials Science, Condensed Matter - Mesoscale and Nanoscale Physics
Abstract

The contrast formation mechanism in Nanoscale Infrared Spectroscopy (Nano-IR or AFM-IR) is analyzed for the boundary between two layers with different light absorption, thermal and elastic parameters. Analytical results derived in the decoupling approximation for low frequency limit show that the response amplitude is linearly proportional to the intensity of the illuminating light and thermal expansion coefficient. The spatial resolution between two dissimilar materials is linearly proportional to the sum of inverse light adsorption coefficients and to the effective thermal transfer length. The difference of displacements height across the T-shape boundary ("thermo-elastic step") is proportional to the difference of the adsorption coefficients and inversely proportional to the heat transfer coefficient. The step height becomes thickness-independent for thick films and proportional to h^2 in a very thin film, Comment: 24 pages (including supplementary materials), 3 figues, 1 table

Published
2017

11. Controlling the topological sector of magnetic solitons in exfoliated Cr$_{1/3}$NbS$_2$ crystals

Author

Wang, L., Chepiga, N., Ki, D. -K., Li, L., Li, F., Zhu, W., Kato, Y., Ovchinnikova, O. S., Mila, F., Martin, I., Mandrus, D., and Morpurgo, A. F.

Subjects
Condensed Matter - Mesoscale and Nanoscale Physics
Abstract

We investigate manifestations of topological order in monoaxial helimagnet Cr$_{1/3}$NbS$_2$ by performing transport measurements on ultra-thin crystals. Upon sweeping the magnetic field perpendicularly to the helical axis, crystals thicker than one helix pitch (48 nm) but much thinner than the magnetic domain size ($\sim$1 $\mu$m) are found to exhibit sharp and hysteretic resistance jumps. We show that these phenomena originate from transitions between topological sectors with different number of magnetic solitons. This is confirmed by measurements on crystals thinner than 48 nm --in which the topological sector cannot change-- that do not exhibit any jump or hysteresis. Our results show the ability to deterministically control the topological sector of finite-size Cr$_{1/3}$NbS$_2$ and to detect inter-sector transitions by transport measurements., Comment: 7 pages, 8 figures

Published
2017
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40. A dedicated C-6 β-hydroxyacyltransferase required for biosynthesis of the glycolipid anchor for Vi antigen capsule in typhoidal Salmonella.

Author

Liston, S. D., Ovchinnikova, O. G., Kimber, M. S., and Whitfield, C.

Subjects
*ACYLTRANSFERASES, *SALMONELLA enterica serovar Typhi, *GLYCOLIPIDS, *BIOSYNTHESIS, *SALMONELLA typhi, *ATP-binding cassette transporters, *SALMONELLA, *CITROBACTER freundii
Abstract

Vi antigen is an extracellular polysaccharide produced by Salmonella enterica Typhi, Citrobacter freundii, and some soil bacteria belonging to the Burkholderiales. In Salmonella Typhi, Vi-antigen capsule protects the bacterium against host defenses, and the glycan is used in a current glycoconjugate vaccine to protect against typhoid. Vi antigen is a glycolipid assembled in the cytoplasm and translocated to the cell surface by an export complex driven by an ABC transporter. In Salmonella Typhi, efficient export and cell-surface retention of the capsule layer depend on a reducing terminal acylated-HexNAc moiety. Although the precise structure and biosynthesis of the acylated terminus has not been resolved, it distinguishes Vi antigen from other known glycolipid substrates for bacterial ABC transporters. The genetic locus for Vi antigenbiosynthesis encodes a single acyltransferase candidate (VexE), which is implicated in the acylation process. Here, we determined the structure of the VexE in vitro reaction product by mass spectrometry and NMR spectroscopy to reveal that VexE catalyzes β-hydroxyacyl-ACP dependent acylation of the activated sugar precursor, uridine-50-diphospho-GlcNAc, at C-6 to form UDP-6-O-[β-hydroxymyristoyl]-α-D-GlcNAc. VexE belongs to the lysophosphatidyl acyltransferase family, and comparison of an Alphafold VexE model to solved lysophosphatidyl acyltransferase structures, together with modeling enzyme:substrate complexes, led us to predict an enzyme mechanism. This study provides new insight into Vi terminal structure, offers a new model substrate to investigate the mechanism of glycolipid ABC transporters, and adds biochemical understanding for a novel reaction used in the synthesis of an important bacterial virulence factor. [ABSTRACT FROM AUTHOR]

Published
2022
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