Asymptotics of geometric characteristics of smooth manifolds in the phase flows

The work is devoted to the study of the asymptotics of the geometric characteristics of smooth manifolds in phase flows. One of the main such characteristics is the Richie curvature of the manifold with respect to the tangent vector

Multibound soliton formation in an erbium-doped ring laser with a highly nonlinear resonator

We have studied the generation of low-noise ultrashort multibound solitons in the telecommunication spectral window in an erbium-doped all-fiber ring laser with a highly-nonlinear resonator mode-locked by a nonlinear polarization evolution effect. The multibound soliton generation is obtained with more than 20 bound dechirped pulses with a duration of 240 fs at a repetition rate of 11.3 MHz (with a signal-To-noise ratio of 73.3 dB), the relative intensity noise is <-140 dBc/Hz, and the Allan deviation of the repetition frequency does not exceed $\sim 1.3\cdot 10^{\mathbf {-8}}$ with a time averaging window of 100 s

Multibound solitons generation with a controllable number of bound states in a passive mode-locked all-fiber erbium-doped ring laser

We have studied generation of stable and low-noise de-chirped ultrashort solitons in bound states and we have experimentally demonstrated the formation multi-bound solitons with the controllable number of bound states 7 < N < 17 by pump power variation. A numerical simulation of the influence of various types of fluctuations on the generation mode was also carried out

Time-dependent systemic hemostatic effects of fibrin monomer in controlled liver injury in the experiment

Aim. To evaluate the hemostatic effect of fibrin monomer after its intravenous administration at different time periods in experimental trauma. Methods. In the experiments, in a placebo-controlled study, hemostatic and hemostasiological effects of systemic use of fibrin monomer were studied at different time periods after its administration (in 5 min, 1 h and 3 h) in 97 male rabbits of the Chinchilla breed in the controlled liver injury model. Results. A pronounced hemostatic effect was demonstrated for fibrin monomer used at a dose of 0.25 mg/kg demonstrated by a 6.3-fold decrease of blood loss volume (% of circulating blood volume) compared to placebo on the background of the intravenous preventive fibrin monomer administration 1 hour prior to controlled liver injury. Fibrin monomer administration at a stated dose was not accompanied by significant changes in haemocoagulative parameters including measurement of platelet count, activated partial thromboplastin time, prothrombin time, thrombin time, echitox time, fibrinogen concentration, level of soluble fibrin monomer complexes, D-dimer content, and antithrombin III activity. The effect of fibrin monomer is probably realized through some effectors, the nature of which has not yet been studied. The obtained results allow choosing the optimal interval between intravenous administrations of fibrin monomer and controlled liver injury for further study of the mechanisms of its hemostatic action. Conclusion. Fibrin monomer in small doses (0.25 mg/kg) is able to exert a pronounced hemostatic effect with its systemic administration 1 hour prior to the injury without significant changes in haemocoagulative parameters

Current State of the Issue of Hemorrhagic Fever with Renal Syndrome in the Rostov Region

Hemorrhagic fever with renal syndrome (HFRS) is registered in various geographical regions of the Russian Federation and occupies one of the leading positions among natural-focal human diseases in Russia. The aim of the study was to assess the epidemiological situation on HFRS in the Rostov Region. Materials and methods. Laboratory diagnostics of field material (samples from wild rodents) for the presence of antigens of HFRS pathogens and screening of blood sera from donors, residents of the region, for the presence of class G antibodies to viruses that cause HFRS were carried out by enzyme immunoassay during 2020 and 2021. Results and discussion. Hantavirus antigens were identified in five administrative districts of the Region in 2020, infection with HFRS virus in small mouse-like rodents was 7.1 %. In 2021, spontaneous infection of carriers was detected in 2.8 % of the samples, found in four districts of the Region. The presence of the virus markers was recorded in populations of five species of mouse-like rodents: house mouse, wood mouse, common vole, small wood mouse, yellow-bellied mouse. Among healthy population, class G antibodies were registered in 6.8 % in the surveyed territories in 2020, and 4.5 % in 2021. Detection of virus markers in carriers and the presence of a natural immune layer of the population as regards HFRS agents suggest the existence of a natural HFRS focus in the Rostov Region

Epizooty of Tularemia, Detected in the Population of the Common Vole in the Natural Focus of Steppe Type in the South-East of the Rostov Region in 2020

The aim of study was to conduct epizootiological monitoring of natural tularemia foci of the steppe type and investigate epizootic activity in the south-east of the Rostov Region.Materials and methods. An epizootiological survey was carried out on the territory of Remontnensky, Sal’sky and Peschanokopsky districts of the Rostov Region in 2019–2021. To capture and collect mammals, Ixodidae ticks and to study the samples of field material conventional methods were used.Results and discussion. Habitation of 16 species of small mammals, 6 species of Ixodidae ticks has been found. Molecular-genetic analysis of the voles has revealed the presence of the species Microtus arvalis obscurus in the studied area of the region. The circulation of the tularemia agent has been established in the population of common and social voles, forest mouse, hare, rook, Dermacentor marginatus, Hyalomma marginatum, removed from rooks. In May 2020, a high increase in the number of the social vole in the Remontnensky district (up to 21 %), in July 2020 – the common vole in the agrocenoses of the Sal’sky district (up to 33 %) was observed. An extensive epizooty of tularemia was detected in the population of common vole in the south-east of the Rostov Region and in adjacent territories in the Republic of Kalmykia and the Stavropol territory. Two cultures of the pathogen were isolated from the fallen and captured social voles, and four cultures – from the common vole. The isolated strains belong to the Holarctic subspecies of Francisella tularensis EryR. The results obtained attest to the activation of the natural tularemia focus in the south-east of the Rostov Region and its high epizootic activity

Novel techniques for alpha/beta pulse shape discrimination in Borexino

Borexino could efficiently distinguish between alpha and beta radiation in its liquid scintillator by the characteristic time profile of their scintillation pulse. This alpha/beta discrimination, first demonstrated at the tonne scale in the Counting Test Facility prototype, was used throughout the lifetime of the experiment between 2007 and 2021. With this method, alpha events are identified and subtracted from the beta-like solar neutrino events. This is particularly important in liquid scintillator as alpha scintillation is quenched many-fold. In Borexino, the prominent Po-210 decay peak was a background in the energy range of electrons scattered from Be-7 solar neutrinos. Optimal alpha-beta discrimination was achieved with a "multi-layer perceptron neural network", which its higher ability to leverage the timing information of the scintillation photons detected by the photomultiplier tubes. An event-by-event, high efficiency, stable, and uniform pulse shape discrimination was essential in characterising the spatial distribution of background in the detector. This benefited most Borexino measurements, including solar neutrinos in the \pp chain and the first direct observation of the CNO cycle in the Sun. This paper presents the key milestones in alpha/beta discrimination in Borexino as a term of comparison for current and future large liquid scintillator detectorsComment: 13 pages, 14 figure

Borexino's search for low-energy neutrinos associated with gravitational wave events from GWTC-3 database

The search for neutrino events in correlation with gravitational wave (GW) events for three observing runs (O1, O2 and O3) from 09/2015 to 03/2020 has been performed using the Borexino data-set of the same period. We have searched for signals of neutrino-electron scattering with visible energies above 250 keV within a time window of 1000 s centered at the detection moment of a particular GW event. The search was done with three visible energy thresholds of 0.25, 0.8 and 3.0 MeV.Two types of incoming neutrino spectra were considered: the mono-energetic line and the spectrum expected from supernovae. The same spectra were considered for electron antineutrinos detected through inverse beta-decay (IBD) reaction. GW candidates originated by merging binaries of black holes (BHBH), neutron stars (NSNS) and neutron star and black hole (NSBH) were analysed separately. Additionally, the subset of most intensive BHBH mergers at closer distances and with larger radiative mass than the rest was considered. In total, follow-ups of 74 out of 93 gravitational waves reported in the GWTC-3 catalog were analyzed and no statistically significant excess over the background was observed. As a result, the strongest upper limits on GW-associated neutrino and antineutrino fluences for all flavors (\nu_e, \nu_\mu, \nu_\tau) have been obtained in the (0.5 - 5.0) MeV neutrino energy range.Comment: 13 pages, 8 figure

Experimental Detection of the CNO Cycle

Borexino recently reported the first experimental evidence for a CNO neutrino. Since this process accounts for only about 1% of the Sun’s total energy production, the associated neutrino flux is remarkably low compared to that of the pp chain, the dominant hydrogen-burning process. This experimental evidence for the existence of CNO neutrinos was obtained using a highly radio-pure Borexino liquid scintillator. Improvements in the thermal stabilization of the detector over the last five years have allowed us to exploit a method of constraining the rate of 210Bi background. Since the CNO cycle is dominant in massive stars, this result is the first experimental evidence of a major stellar hydrogen-to-helium conversion mechanism in the Universe