The sectional curvature remains positive when taking quotients by certain nonfree actions

We study some cases when the sectional curvature remains positive under the taking of quotients by certain nonfree isometric actions of Lie groups. We consider the actions of the groups $S^1$ and $S^3$ such that the quotient space can be endowed with a smooth structure using the fibrations $S^3/S^1{\simeq}S^2$ and $S^7/S^3\simeq S^4$. We prove that the quotient space carries a metric of positive sectional curvature, provided that the original metric has positive sectional curvature on all 2-planes orthogonal to the orbits of the action.Comment: 26 pages, 1 figure. Changed the spelling of the author's nam

Tuning of tunneling current noise spectra singularities by localized states charging

We report the results of theoretical investigations of tunneling current noise spectra in a wide range of applied bias voltage. Localized states of individual impurity atoms play an important role in tunneling current noise formation. It was found that switching "on" and "off" of Coulomb interaction of conduction electrons with two charged localized states results in power law singularity of low-frequency tunneling current noise spectrum ($1/f^{\alpha}$) and also results on high frequency component of tunneling current spectra (singular peaks appear).Comment: 7 pages, 4 figure

Optimization of the Process of Cholera Chemical Pelleted Vaccine Production Using Ultrafiltration Technology

Technology of O-antigen obtaining from Vibrio cholerae M41production strain, using the hollow fiber ultrafiltration modules, is developed and introduced into cholera vaccine manufacturing. Application of ultrafiltration makes it possible to obtain native high-activity O-antigen preparations which comply with the current regulatory requirements. Besides, it provides for economy (10-15-fold) of ammonium sulphate, used for antigen precipitation, reduces the duration of technological cycle (2 times), and the labor inputs. The technology of protective antigen concentrating is tested on V. cholerae strains MO45 and KM137 of O139 serogroup. Three series of experimental V. cholerae O139 vaccine are obtained

B-lymphocyte aggregation in the lung tissue is a pathogenic factor in experimental infection caused by Mycobacterium avium

When infecting the lungs with Mycobacterium avium of B6 line mice genetically susceptible to this infection the compact aggregates (follicles) of B-lymphocytes are formed with the peak at the 11-13th week after the infection. Physiological role of these cellular accumulations remained unclear. Having applied segregative genetic analysis to allele conglutination of Slc11a1 gene with two signs – quantity of mycobacteria and accumulation of B-cellular follicles to the F2 mice from crossing (В6 × I/St), one managed to find out that the quantity and size of follicles directly correlate with M. avium replication in the lungs. Thus this type of the lung tissue infiltration does not protect the host from infection and it is a pathogenic factor

On the phenomenology of a Z' coupling only to third-family fermions

The phenomenology of an additional U(1) neutral gauge boson Z' coupled to the third family of fermions is discussed. One might expect such a particle to contribute to processes where taus, b and t quarks are produced. Precision data from LEP1 put severe constraints on the mixing and heavy-boson mass. We find that the effects of such a particle could not be observed at hadronic colliders, be it at the Tevatron or the LHC, because of the QCD background. At LEP2 and future e^+e^- linear colliders, one could instead hope to observe such effects, in particular for b\bar b final states.Comment: 36 pages, LaTeX, including 12 figure

High orders of perturbation theory: are renormalons significant?

According to Lipatov, the high orders of perturbation theory are determined by saddle-point configurations (instantons) of the corresponding functional integrals. According to t'Hooft, some individual large diagrams, renormalons, are also significant and they are not contained in the Lipatov contribution. The history of the conception of renormalons is presented, and the arguments in favor of and against their significance are discussed. The analytic properties of the Borel transforms of functional integrals, Green functions, vertex parts, and scaling functions are investigated in the case of \phi^4 theory. Their analyticity in a complex plane with a cut from the first instanton singularity to infinity (the Le Guillou - Zinn-Justin hypothesis) is proved. It rules out the existence of the renormalon singularities pointed out by t'Hooft and demonstrates the nonconstructiveness of the conception of renormalons as a whole. The results can be interpreted as an indication of the internal consistency of \phi^4 theory.Comment: 28 pages, 8 figures include

Epizootiological and Epidemiological Situation on Tularemia in Russia in 2020, the Forecast for 2021

The purpose of the review is to assess the trends in the development of epizootic activity in various territories of the Russian Federation in order to identify the regions of increased risk of infection of the population with tularemia pathogen in 2021 and to plan and carry out high-priority measures in these regions, such as vaccination, investments in water, sanitation and hygiene infrastructure, epizootiological monitoring of natural foci and other measures aimed at suppressing the activity of natural foci and the development of herd immunity to this infection. In 2020, 41 cases of human infection with tularemia pathogen were registered on the territory of the Russian Federation, 60 % of which occurred in the Northwestern Federal District. Epizootic manifestations of the infection of varying intensity were detected in 55 constituent entities of Russia. Against this background, sporadic cases of tularemia in humans were registered in 14 regions of the country. The most pronounced epidemic complications continue in the territory of Karelia – 23 patients. 12 cultures of Francisella tularensis subsp. holarctica from the ambient environment were isolated in the Vologda (3), Rostov Regions (6), in the Khanty-Mansi Autonomous District (2), and in St. Petersburg (1). Based on the analysis of the data presented, in 2021, epidemic complications in the form of sporadic cases of the disease among the unvaccinated population in the following territories are most likely to occur: Central Federal District – in the Oryol, Ryazan and Yaroslavl Regions, as well as in Moscow; Northwestern Federal District – in the Arkhangelsk and Leningrad Regions, the Republic of Karelia and in St. Petersburg; Volga Federal District – in Tatarstan, Mordovia, Chuvash Republic, Kirov and Orenburg Regions; Ural Federal District – in the Khanty-Mansiysk, Yamalo-Nenets Autonomous Districts and the Tyumen Region; Siberian Federal District – in the Novosibirsk, Kemerovo, Tomsk and Omsk Regions, as well as in the Altai Territory; Far Eastern Federal District – in some regions of Kamchatka and Khabarovsk Territories

Genetic Diversity of the Family <i>Francisellaceae</i>, Analysis of the situation on tularemia Incidence in the Russian Federation in 2021, and Forecast for 2022

The review briefly outlines the current taxonomy of the most studied strains of the species belonging to the family Francisellaceae. Due to the significant genetic diversity within the family, the detection of Francisella tularensis, especially in environmental samples, becomes even more difficult and may lead to false positive results. A comparison of the incidence rates in European countries, in which the extensive epidemic manifestations of tularemia are recorded annually, namely Sweden, Finland, Norway and the Czech Republic, and in Russia over the past five years is provided. The paper presents the comparative dynamics of tularemia incidence in the territories of the Federal Districts of the Russian Federation in recent years. The dynamics of the incidence during epidemic outbreaks in the Republic of Karelia and the Omsk Region over the past few years is shown. 17 cases of human infection with the causative agent of tularemia were registered on the territory of the Russian Federation in 2021. Epizootic manifestations of the infection of varying degrees of intensity were detected in 45 constituent entities of the Federation. Against that background, sporadic cases of tularemia in humans were reported in 11 regions of the country. Six cultures of Francisella tularensis subsp. mediasiatica from different types of ticks were isolated in the Krasnoyarsk Territory, the Republic of Altai and the Altai Territory. Based on the analysis of the data presented, in 2022, epidemic complications in the form of sporadic cases of the disease are most likely to occur among the unvaccinated population in the territories of the Central Federal District – the Voronezh, Ryazan, Smolensk Regions and in Moscow; Northwestern Federal District – in the Arkhangelsk Region, the Republic of Karelia and in St. Petersburg; Volga Federal District – in the territories of Samara, Kirov Regions and Republic of Tatarstan; Ural Federal District – in the Khanty-Mansiysk and Yamalo-Nenets Autonomous Districts; Siberian Federal District – in certain districts of the Kemerovo, Novosibirsk, Omsk and Tomsk Regions, Altai and Krasnoyarsk Territories

Tularemia: Relevant Issues and Forecast of Epidemic Situation in the Territory of the Russian Federation in 2018

168 cases of human infection with Francisella tularensis were registered in the Russian Federation in 2017. 80 % of the cases are accounted for by three Federal Districts: North-Western, North-Caucasian, and Siberian ones. Epizootic manifestations of the infection of varying intensity were reported in 61 constituent entities of the Russian Federation. High morbidity rates in 2017 were observed in the Stavropol Territory – 49 tularemia cases, in the Republic of Karelia – 40, Omsk Region – 20, and Saint Petersburg – 12. To assess epizootic and epidemic situation in each constituent entity of the Federation, the numbers of small mammals and their species composition, infection rates of rodents, ticks, mosquitoes, horseflies, hunting animals, nests, regurgitates of birds of prey and excrements of carnivores, surface water bodies, agent culture numbers, isolated from clinical samples, animals, ticks and water, as well as the data on incidence and vaccination of the population in the region were analyzed. The conclusion has been drawn in regard to the territories where epidemic complications are most likely to occur in 2018