Pauli-principle driven correlations in four-neutron nuclear decays

Mechanism of simultaneous non-sequential four-neutron ($4n$) emission (or `true' $4n$-decay) has been considered in phenomenological five-body approach. This approach is analogous to the model of the direct decay to the continuum often applied to $2n$- and $2p$-decays. It is demonstrated that $4n$-decay fragments should have specific energy and angular correlations reflecting strong spatial correlations of `valence' nucleons orbiting in their $4n$-precursors. Due to the Pauli exclusion principle, the valence neutrons are pushed to the symmetry-allowed configurations in the $4n$-precursor structure, which causes a `Pauli focusing' effect. Prospects of the observation of the Pauli focusing have been considered for the $4n$-precursors $^7$H and $^{28}$O. Fingerprints of their nuclear structure or/and decay dynamics are predicted

Updated analysis of NN elastic scattering to 3 GeV

A partial-wave analysis of NN elastic scattering data has been updated to include a number of recent measurements. Experiments carried out at the Cooler Synchrotron (COSY) by the EDDA Collaboration have had a significant impact above 1 GeV. Results are discussed in terms of the partial-wave and direct-reconstruction amplitudes.Comment: 16 pages, 14 figures, 2 tables; Fig 10 error corrected; Accepted for publication in Physical Review

Hadronic Regge Trajectories: Problems and Approaches

We scrutinized hadronic Regge trajectories in a framework of two different models --- string and potential. Our results are compared with broad spectrum of existing theoretical quark models and all experimental data from PDG98. It was recognized that Regge trajectories for mesons and baryons are not straight and parallel lines in general in the current resonance region both experimentally and theoretically, but very often have appreciable curvature, which is flavor-dependent. For a set of baryon Regge trajectories this fact is well described in the considered potential model. The standard string models predict linear trajectories at high angular momenta J with some form of nonlinearity at low J.Comment: 15 pages, 9 figures, LaTe

Refinements to the microwave waveguide material parameters measurements. Case study

This work presents the results of experimental measurements of permittivity and permeability of materials (dried pine, paraffin, acrylic resin, bitumen, polypropylene and texolite) that has a comparative values. The laboratory installation compile from waveguides 23x10 mm that provides the frequency range 8-12 GHz. The results processing lay not only in comparison with the existing data, but also in investigation of physical conditions that should be taken into account for waveguide experiment setup. The main aim is to establish the variation of electro physical parameters of the material measured in waveguides and in free space. Selection of reference material samples is the main part of this work. © 2019 Published under licence by IOP Publishing Ltd

Developing civic competence through the art of the word (based on K.Gordienko’s literary works)

Summary. The paper is aimed at an characterization of the word art means for civic competence fostering based on K. Gordienko’s literary contribution, at the report on development and use of electronic tools for educational assignment with a view of mastering better the writer’s works. The comprehensive analysis of the writer’s literary heritage gave an opportunity to clarify the role and place of the writer and his works in the context of literary and aesthetic aspirations of Ukrainian literature of XX century and to determine his national-patriotic views. In order to improve the quality of the civil culture formation process there was developed an electronic tool for educational purposes, which contains the theoretical material, literary work, epistolary, photo gallery and video materials about K. Gordienko

Variability of Active Galactic Nuclei from the Optical to X-ray Regions

Some progress in understanding AGN variability is reviewed. Reprocessing of X-ray radiation to produce significant amounts of longer-wavelength continua seems to be ruled out. In some objects where there has been correlated X-ray and optical variability, the amplitude of the optical variability has exceeded the amplitude of X-ray variability. We suggest that accelerated particles striking material could be linking X-ray and optical variability (as in activity in the solar chromosphere). Beaming effects could be significant in all types of AGN. The diversity in optical/X-ray relationships at different times in the same object, and between different objects, might be explained by changes in geometry and directions of motion relative to our line of sight. Linear shot-noise models of the variability are ruled out; instead there must be large-scale organization of variability. Variability occurs on light-crossing timescales rather than viscous timescales and this probably rules out the standard Shakura-Sunyaev accretion disk. Radio-loud and radio-quiet AGNs have similar continuum shapes and similar variability properties. This suggests similar continuum origins and variability mechanisms. Despite their extreme X-ray variability, narrow-line Seyfert 1s (NLS1s) do not show extreme optical variability.Comment: Invited talk given at Euro Asian Astronomical Society meeting in Moscow, June 2002. 20 pages, 4 figures. References update

Site-specific characterisation of SARS-CoV-2 spike glycoprotein receptor binding domain

The novel coronavirus SARS-CoV-2, the infective agent causing COVID-19, is having a global impact both in terms of human disease as well as socially and economically. Its heavily glycosylated spike glycoprotein is fundamental for the infection process, via its receptor binding domains interaction with the glycoprotein angiotensin converting enzyme 2 on human cell surfaces. We therefore utilized an integrated glycomic and glycoproteomic analytical strategy to characterise both N- and O- glycan site specific glycosylation within the receptor binding domain. We demonstrate the presence of complex type N-glycans with unusual fucosylated LacdiNAc at both sites N331 and N343 and a single site of O-glycosylation on T323

Three-body correlations in direct reactions: Example of 6^{6}Be populated in (p,n)(p,n) reaction

The $^{6}$Be continuum states were populated in the charge-exchange reaction $^1$H($^{6}$Li,$^{6}$Be)$n$ collecting very high statistics data ($\sim 5 \times 10^6$ events) on the three-body $\alpha$+$p$+$p$ correlations. The $^{6}$Be excitation energy region below $\sim 3$ MeV is considered, where the data are dominated by contributions from the $0^+$ and $2^+$ states. It is demonstrated how the high-statistics few-body correlation data can be used to extract detailed information on the reaction mechanism. Such a derivation is based on the fact that highly spin-aligned states are typically populated in the direct reactions.Comment: submitted to Physical Review

Conductive AFM study of the electronic properties of vertical GaN nanowires

V.A.S. thanks for support of the heterostructures characterization and K.Yu.S. thanks for support of the experimental data analysis the Ministry of Science and Higher Education of the Russian Federation (Grants 16.2593.2017/4.6 and 3.9796.2017/8.9, correspondingly), V.V.F. and A.M.M. thanks for support of the growth processes the Russian Federation President Council for grants (MK-1204.2019.2 and SP-2324.2018.1, correspondingly)

EXPERIMENTAL STUDY OF THE REFRACTIVE PROPERTIES OF THE WATER FLOW WITH HIGH-DISPERSITY IMPURITIES

The work describes all stages of planning and preparing a full-scale experiment to study the refractive properties of the water flow, including those with high-dispersity impurities, at the microwave range. The experiment is carried out using standard waveguides. The impurity used is an iron micro powder. In addition to the refractive properties, the adjacent pa-rameter is the coefficient of drag