Features of developing SARS-CoV-2 nucleocapsid protein population-based seroprevalence during the first wave of the COVID-19 epidemic in the Russian Federation

The novel coronavirus (SARS-CoV-2) pandemic, dubbed COVID-19, has become one of the most serious challenges for human populations in the vast majority of countries worldwide. Rapid spreading and increased mortality related to it required new approaches to manage epidemic processes on a global scale. One of such approaches was based on analyzing SARS-CoV-2 seroprevalence associated with COVID-19. Our aim was to summarize the results on assessing seroprevalence to the SARS-CoV-2 nucleocapsid antigen (Nc) in residents from 26 regions of the Russian Federation, carried out during the first wave of the COVID-19 epidemic.Materials and methods. Seroprevalence distribution was examined in 26 model regions of the Russian Federation according to the unified method developed by the Rospotrebnadzor with the participation of the Federal State Institution Saint Petersburg Pasteur Research Institute of Epidemiology and Microbiology. Such approach implied formation of a group of volunteer subjects in model geographic region who were tested by ELISA for anti-Nc serum antibody level in peripheral blood. Analyzed primary data obtained in separate regions were either accepted for publication or released.Results. The current paper finalizes the data obtained in all 26 regions of the Russian Federation. The total SARS-CoV-2 seroprevalence was 19.5 (10.0–25.6)% with the maximum and minimum value found in the Kaliningrad Region and the Republic of Crimea, respectively (50.2% vs. 4.3%). A pattern of age-related seroprevalence distribution indicates insignificant predominance of seroprevalence among subjects of 1–17 years old: 22.1 (13.1–31.8)%. Among COVID-19 convalescents positive for SARS-CoV Nc antibodies it reached 60.0 (40.0–73.3)%. The number of contact persons comprised 6285 subjects or 8.5% of total volunteer cohort, with the level of seroprevalence reaching up to 25.3 (17.95–35.8)%. A direct correlation was revealed between levels of seroprevalence in convalescent and contact volunteers. In addition, the reproductive number for SARS-CoV was calculated comprising 5.8 (4.3–8.5) suggesting that one convalescent subject can infect at least 4 healthy individuals. A high level of asymptomatic forms of COVID-19 among seropositive subjects was confirmed empirically comprising up to 93.6 (87.1–94.9)%.Conclusion. A single cross-sectional study performed during 2020 June–August timeframe allowed to assess pattern of sex- and agerelated COVID-19 seroprevalence for general population in 26 Russian Federation regions. The data obtained may serve as a basis for the longitudinal cohort investigation with serial subject sampling. The timing and duration of study will be determined by dynamics of ongoing COVID-19 epidemic

Fragmentation and Multifragmentation of 10.6A GeV Gold Nuclei

We present the results of a study performed on the interactions of 10.6A GeV gold nuclei in nuclear emulsions. In a minimum bias sample of 1311 interac- tions, 5260 helium nuclei and 2622 heavy fragments were observed as Au projec- tile fragments. The experimental data are analyzed with particular emphasis of target separation interactions in emulsions and study of criticalexponents. Multiplicity distributions of the fast-moving projectile fragments are inves- tigated. Charged fragment moments, conditional moments as well as two and three -body asymmetries of the fast moving projectile particles are determined in terms of the total charge remaining bound in the multiply charged projectile fragments. Some differences in the average yields of helium nuclei and heavier fragments are observed, which may be attributed to a target effect. However, two and three-body asymmetries and conditional moments indicate that the breakup mechanism of the projectile seems to be independent of target mass. We looked for evidence of critical point observable in finite nuclei by study the resulting charged fragments distributions. We have obtained the values for the critical exponents gamma, beta and tau and compare our results with those at lower energy experiment (1.0A GeV data). The values suggest that a phase transition like behavior, is observed.Comment: latex, revtex, 28 pages, 12 figures, 3tables, submitted to Europysics Journal

Physics of Auroral Phenomena

Abstract. The influence of the main ionospheric trough location on the oblique HF propagation along the route Murmansk to St. Petersburg is investigated by means of model simulation. First, four distinct electron concentration distributions along the route considered are calculated using the mathematical model of the high-latitude ionosphere. One of the distributions does not contain any anomalies. Other three include the main ionospheric trough, which depth and width are identical but the distances from the beginning of the route are different. Then, the problem of how the main ionospheric trough affects the oblique HF propagation is examined by utilizing a two-dimensional ray-tracing computer program. The obtained distributions of the electron concentration are used to synthesize the ionograms of oblique sounding along the sub-auroral route using the above program. The results suggest that the location of the ionospheric trough essentially affects the form of the ionograms of oblique sounding

Charged-particle multiplicity and angular distributions in proton-emulsion interactions at 800 GeV

The interaction of 800-GeV protons in nuclear emulsion has been investigated. The multiplicities and angular distributions of charged particles emitted by both the projectile and the target nucleus have been measured for 1718 inelastic events and are compared with the data obtained in proton-emulsion collisions at 67, 200, and 400 GeV. The target excitation is found to be independent of energy while the production of secondary particles continues to increase with incident proton energy. © 1987 The American Physical Society

Correlations among particles produced in proton interactions with emulsion nuclei at 800 GeV

Correlations among the produced particles in interactions of 800-GeV protons with nuclei in photographic emulsion provide evidence for nonindependent production of the secondary particles. Assuming particle production in clusters, the analysis implies an average multiplicity of about 3 charged particles per cluster. © 1988 The American Physical Society

Angular distributions in proton-nucleus interactions in emulsion at 800 GeV

Data on angular distributions of heavily ionizing and shower particles in incoherent protonnucleus collisions in emulsion at 800 GeV are reported and discussed in details. Dependence of angular distributions on the mass number of a target nucleus and on the multiplicity of charged particles is investigated. The data presented are systematically compared with results of emulsion experiments at lower energies and with predictions of the Lund Monte Carlo model FRITIOF. © 1988 Springer-Verlag

Central collisions of 800-GeV protons with Ag/Br nuclei in nuclear emulsion

Central collisions of 800-GeV protons with the heavy components of nuclear emulsion, Ag107 and Br80, have been investigated to determine the characteristics of small-impact-parameter collisions and, by comparison with the analysis of inclusive proton-emulsion inelastic interactions and inelastic proton-nucleon collisions, to study the dependence of the interaction process on the mean number of intranuclear collisions . The data are also compared with the results obtained in proton-emulsion collisions, both central and inclusive, at 200 GeV. The variations in the secondary-particle multiplicities and the normalized pseudorapidity density correlate with and demonstrate that proton-nucleus interactions, both central and inclusive, can be described adequately by the incoherent superposition of proton-nucleon collisions. © 1989 The American Physical Society

Measurements of 525 GeV pion interactions in emulsion

Measurements have been made of inclusive 525 GeV π- interactions in emulsion. The results are compared to proton-emulsion and lower energy pion-emulsion data. Average multiplicities of relativistic shower particles increase with increasing energy, although with a somewhat steeper slope above 60 GeV than at lower energies. The ratio nsp/nsπ∼1.1 over the energy range 60-525 GeV. The ratio of the dispersion in the multiplicity distribution to the average multiplicity is the same for proton and pion collisions in emulsion, and is independent of projectile energy. The shape of the shower particle multiplicity distribution does not vary significantly with energy, and KNO scaling appears to hold over the energy range 60-525 GeV. The shower particle pseudorapidity distributions are independent of the beam energy in the target and projectile fragmentation regions, and both the pseudorapidity and multiplicity distributions agree reasonably well with the fritiof model predictions for 525 GeV pions. The dependence of the shower particle multiplicity ns on the number of heavy tracks Nh appraoches saturation as the total shower particle energy becomes a significant fraction of s, and the pseudorapidity distributions shift toward smaller η with increasing numbers of grey and black tracks at 525 GeV. Neither the average number Nh nor the multiplicity distributions of the heavily ionizing tracks vary significantly with energy, and the normalized angular distributions of grey and black tracks are independent of the type of projectile or projectile energy. © 1994 The American Physical Society