Wormholes and Naked Singularities in Brans-Dicke cosmology

We perform analytical and numerical study of static spherically symmetric solutions in the context of Brans-Dicke-like cosmological model by Elizalde et al. with an exponential potential. In this model the phantom regime arises without the appearance of any ghost degree of freedom due to the specific form of coupling. For the certain parameter ranges the model contains a regular solution which we interpret as a wormhole in an otherwise dS Universe. We put several bounds on the parameter values: $\omega<0 ,\,\, \alpha^2/|\omega|<10^{-5},22.7\lesssim\!\phi_0\!\lesssim25\,$. The numerical solution could mimic the Schwarzschild one, so the original model is consistent with astrophysical and cosmological observational data. However differences between our solution and the Schwarzschild one can be quite large, so black hole candidate observations could probably place further limits on the $\phi_0$ value.Comment: 20 pages, 6 figures, typos & errors correcte

Stable black holes in shift-symmetric Horndeski theories

In shift-symmetric Horndeski theories, a static and spherically symmetric black hole can support linearly time-dependent scalar hair. However, it was shown that such a solution generically suffers from ghost or gradient instability in the vicinity of the horizon. In the present paper, we explore the possibility to avoid the instability, and present a new example of theory and its black hole solution with a linearly time-dependent scalar configuration. We also discuss the stability of solutions with static scalar hair for a special case where nonminimal derivative coupling to the Einstein tensor appears. © 2017 IOP Publishing Ltd

Study of computer addiction in modern school

Describes a problem of dependence on computer games at modern school. Examines the State of dependency and level of students in 10-12 yearsВ статье описывается проблема зависимости от компьютерных игр в современной школе, анализируется состояние зависимости и уровень учащихся в 10-12 ле

Demand of IT specialties in the economic and educational sector

The demand of IT specialties is shown in article. The modern range of the IT directions of preparation is determined by the Russian higher education institutions and also the level of demand of this direction at foreign students. Characteristic of the IT specialties which are most demanded in the world is givenВ статье показана востребованность IT-специальностей. Определен современный спектр IT-направлений подготовки по российским вузам, а также уровень востребованности данного направления у иностранных студентов. Дана характеристика наиболее востребованных в мире IT-специальносте

Distribution of Alien Plant Species of the Middle Volga Region (South-East of the European Part of Russia): a Dataset

Background The dataset presented in the current study contains information regarding alien vascularplant species found in the Middle Volga Region (South-East of the European part ofRussia). The dataset overall includes 413 species belonging to 247 genera and 67families. The described dataset is based on the data published during floristic studies from1851 to 2019. The dataset does not include alien vascular plant species that havepresently disappeared from the territory of the region. It contains a total of 7,782 records ofoccurrences, extracted from the Salix system of information and analytics, developed in theInstitute of Ecology of the Volga River Basin of the Russian Academy of Sciences.New informationA total of 7,782 records were published on the occurrence of alien vascular plants in theMiddle Volga Region. Each entry includes information regarding the place of occurrence ofthe alien plant species, the year of occurrence, the person who recorded the alien plantand who identified it, status of the species (introduced or invasive), link to the herbarium,which contains the specimen and the literary source. If it were impossible to establish thenames of the persons who collected the samples and (or) their identification in theidentifiedBy and recordedBy fields, the names of the authors of the publication given in theassociatedReferences field were entered. The presented dataset supplements theinformation on the distribution of alien plant species in the whole European part of Russiaand specifies the places of their findings in the Middle Volga Region © Senator S et al. This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.Funding: This work was supported by the Competitiveness of the Ural Federal University (Russian Federation Government Regulation no. 211, contract no. 02. A03.21.0006)

Wastewater Afterpurification of Chromium Compounds Production by the Ultrafiltration and Reverse Osmosis

Most often, reagent methods are used to treat wastewater from Cr (VI) compounds. This treatment technology allows reducing the concentration of Cr (VI) in wastewater only. Comparing the composition of wastewater after reagent treatment of chromium compounds using Ca(OH)2 with established standards, it can be concluded that it is necessary to purify a number of pollutants. In this study, wastewater afterpurification of chromium compounds production by the ultrafiltration and reverse osmosis was considered. Modelling processes using WAVE 1.72 software confirmed that the proposed post-treatment scheme was highly efficient and that wastewater could be discharged into a water body without harming it. © Published under licence by IOP Publishing Ltd

Educational institution health service management: Key aspects of communication and interaction within the team

The relevance of the researched problem is caused by the need of ensuring effective interaction of the main members of management of health saving activities - heads of structural subdivisions of the Health Service (HS) of an educational institution. The purpose of the publication consists in the development of conceptual provisions for ensuring interaction of the main members of the HS management team. Systematically-activity approach is a leading approach to research of this problem which allows us to research activities of heads of structural subdivisions of the HS as an object of management and as subjects of a small group. Managers’ activities of structural subdivisions of the HS are researched as the object of management and as activities of members of a small group. Terms of forming the health care management team are offered; processes of interaction of its members are disclosed; the model for aim coordination by the team members, the stages and the principles of this coordination are provided; the criteria of formation and development levels of health care management team and efficiency of its members’ interaction are highlighted. The materials of the publication can be useful to heads and managers of educational institutions regarding the organization and ensuring effective management of health saving activities in the organizations, by means of ensuring interdepartmental integration of the leading experts involved in activities for preservation and promotion of the student health. © 2016 Tretyakova et al

Observation of nuclei with energies 8-30 MeV per nucleon in the Earth's magnetosphere at the altitudes 350 KM

Observations of the flux of nuclei with an energy of IO MeV per nucleon on the Salyut-7 Station in September 1984 are presented. The observed flux is smaller by a factor of 50 than the flux detected in May, 1981

Non-singular Brans-Dicke cosmology with cosmological constant

We consider Brans-Dicke cosmology with cosmological constant with negative w parameter and an arbitrary (in general non-vanishing) scale factor at the Big Bang. The field equations describe the flat universe, current observational values for Hubble constant H and deceleration parameter q play a role of initial conditions. In order to solve field equations we adopt the approach of Uehara and Kim (1982). They considered only positive values of w, hence our solution is a new one and has not been described in their paper. Our main result is that unlike the standard cosmology the scale factor may not vanish in it's evolution back in time. In other words our model displays a cosmological bounce and avoids the initial singularity. The formula for the scale factor, leading to the bounce, is only valid for the dust-filled universe and hence cannot be adequate for the hot stage in the early universe when the bounce happens. So, the results of this paper are only qualitative in nature and must be used to obtain initial values for the hot stage of the unverse when one considers the evolution back in time.Comment: 12 pages, 1 figur