Ion pairing in model electrolytes: A study via three particle correlation functions

A novel integral equations approach is applied for studying ion pairing in the restricted primitive model (RPM) electrolyte, i. e., the three point extension (TPE) to the Ornstein-Zernike integral equations. In the TPE approach, the three-particle correlation functions $g^{[3]}({\bf r}_{1},{\bf r}_{2},{\bf r}_{3})$ are obtained. The TPE results are compared to molecular dynamics (MD) simulations and other theories. Good agreement between TPE and MD is observed for a wide range of parameters, particularly where standard integral equations theories fail, i. e., low salt concentration and high ionic valence. Our results support the formation of ion pairs and aligned ion complexes.Comment: 43 pages (including 18 EPS figs) - RevTeX 4 - J. Chem. Phys. (in press

Interplay between magnetism and superconductivity in Fe-pnictides

We consider phase transitions and potential co-existence of spin-density-wave (SDW) magnetic order and extended s-wave ($s^+$) superconducting order within a two-band itinerant model of iron pnictides, in which SDW magnetism and $s^+$ superconductivity are competing orders. We show that depending on parameters, the transition between these two states is either first order, or involves an intermediate phase in which the two orders co-exist. We demonstrate that such co-existence is possible when SDW order is incommensurate.Comment: 5 pages, 3 figure

Microscopic evidence for field-induced magnetism in CeCoIn5_5

We present NMR data in the normal and superconducting states of CeCoIn$_5$ for fields close to $H_{\rm c2}(0)=11.8$ T in the $ab$ plane. Recent experiments identified a first-order transition from the normal to superconducting state for $H> 10.5$ T, and a new thermodynamic phase below 290 mK within the superconducting state. We find that the Knight shifts of the In(1), In(2) and the Co are discontinuous across the first-order transition and the magnetic linewidths increase dramatically. The broadening differs for the three sites, unlike the expectation for an Abrikosov vortex lattice, and suggests the presence of static spin moments in the vortex cores. In the low-temperature and high-field phase the broad NMR lineshapes suggest ordered local moments, rather than a long wavelength quasiparticle spin density modulation expected for an FFLO phase.Comment: 4 pages, 4 figures. to appear in Phys. Rev. Let

Phase Filters for 3D Localization of Point Light Sources

The work relates to the engineering and research of phase filters for three-dimensional localization of point light emitters. These phase filters form a light field having two clearly visible maxima in their intensity distribution (i.e. two-lobe fields). By means of numerical simulation, the influence of the amplitude and phase distortions of the wave front of the illuminating beam on the two-lobe field formation has been studied in the work. Keywords: spiral light beams, amplitude distortions, phase distortions, threedimensional localization, two-lobe field

Superconductivity and spin-density-waves in multi-band metals

We present a detailed description of two-band quasi-2D metals with s-wave superconducting (SC) and antiferromagnetic spin-density wave (SDW) correlations. We present a general approach and use it to investigate the influence of the difference between the shapes and the areas of the two Fermi surfaces on the phase diagram. In particular, we determine the conditions for the co-existence of SC and SDW orders at different temperatures and dopings. We argue that a conventional s-wave SC order co-exists with SDW order only at very low $T$ and in a very tiny range of parameters. An extended s-wave superconductivity, for which SC gap changes sign between the two bands, co-exists with antiferromagnetic SDW over a much wider range of parameters and temperatures, but even for this SC order the regions of SDW and SC can still be separated by a first order transition. We show that the co-existence range becomes larger if SDW order is incommensurate. We apply our results to iron-based pnictide materials, in some of which co-existence of SDW and SC orders has been detected.Comment: 18 figures, 22 pages, published version with minor correction

The influence of students’ intelligence types and personality traits on academic performance in distance learning in the digital environment

The academic paper investigates the influence of students’ intelligence types and personality traits on academic performance in order to increase the remote (distance) or online learning effectiveness. The research was conducted in 2019–2021 on the basis of three groups of bachelor students who studied in different training forms, namely: full-time (classroom) form in 2019 and 2021 and remote (distance) form in 2020. The students were tested annually in accordance with J. Bruner’s methodology adapted by G.V. Rezapkina in order to determine the leading intelligence types; as well as according to the Russian-language version of the Big Five Inventory questionnaire adapted by S.A. Shchebetenko for the purpose of analysing students’ personal traits. The data obtained in the full-time (classroom) and remote (distance) form of training were processed statistically and compared with each other for interpretation and the practical recommendations formation. The research result was an empirical model of the intelligence types and personality traits influencing academic performance in different training forms. Therefore, as a positive factor in the transfer to distance training mode, the authors highlighted the expressiveness of students’ creative thinking. Conversely, the prevalence of the verbal-logical intelligence type is rather a factor in favour of the classic classroom interaction format. Regardless of the chosen training form, the general relevance of the activation and adaptation of students of humanitarian specialties with a pronounced visual-figurative and subject-effective thinking is emphasised. Previously obtained data on the general positive influence of such personal qualities as: benevolence, conscientiousness and openness to new experience on the training effectiveness are also confirmed. Neuroticism, on the other hand, is an insignificant personal factor that has a negative impact in the framework of the classroom format, and the positive influence in distance training mode. By the way, a hypothesis has been put forward about the lower efficiency of online (as opposed to full-time) team activities, including design works in groups with pronounced extraversion

INTELLIGENT DIGITAL SOLUTIONS FOR INCREASING OPERATIONAL EFFICIENCY AND LABOR PRODUCTIVITY IN ELECTRIC POWER INDUSTRY

We can already say with certainty, that the basis for the development of modern electric power industry will soon be intellectual, digital transformation of production assets, which in itself opens a new approach to the problem of increasing operational efficiency and labor productivity. The main difficulty in this way is, that the existing research of digital technologies do not take into account the applied aspects of the implementation of its products according to the industry specifics and business goals of companies – market entities. In this paper, the analysis and classification of commercial IT products have been made by subject groups of solutions, that meet the needs of specific target areas of activity of electric power companies. The conceptual description of the subject groups of digital solutions on the basis of known examples and practices of their application has been adduced

VV124 (UGC4879): A new transitional dwarf galaxy in the periphery of the Local Group

We present the first resolved-star photometry of VV124 (UGC4879) and find that this is the most isolated dwarf galaxy in the periphery of the Local Group. Based on imaging and spectroscopic follow up observations with the 6m BTA telescope, we resolve VV124 into 1560 stars down to the limiting magnitude levels of V~25.6 and I~23.9. The young blue stellar populations and emission gas are found near the core, but noticeably displaced from the center of the galaxy as traced by dominant evolved red stars. The mean radial velocity derived from the spectra of two Blue Supergiant stars, an HII region and unresolved continuum sources is -80+/-10 km/s. The evolved ``red tangle'' stellar populations, which contains the red giant branch (RGB), are identified at large galactocentric radii. We use the I-band luminosity function to determine the distance based on the Tip of RGB method, 1.1+/-0.1 Mpc. This is ~10 times closer than the values usually assumed in the literature, and we provide revised distance dependent parameters. From the mean (V-I) color of the RGB, we estimate the mean metallicity as [Fe/H]~-1.37 dex. Despite of its isolated location, the properties of VV124 are clearly not those of a galaxy in formation, but rather similar to a transitional dIrr/dSph type.Comment: 4 pages, submitted to MNRAS Letter