Topological phases induced by charge fluctuations in Majorana wires

One of the problems concerning topological phases in solid-state systems which still remains urgent is an issue of many-body effects. In this study we address it within perturbative theory framework by considering topological phase transitions related to charge correlations in the extended Kitaev chain model that belongs to the BDI symmetry class. Obtained corrections to a zero-frequency quasiparticle Green's function allow to separate the mean-field and fluctuation contributions to a total winding number. As a result, the phase transitions caused solely by the latter are unveiled. We thoroughly analyze the mechanism of such transitions in terms of fluctuation-induced nodal points and spectrum renormalization. Additionally, features of other quasiparticle properties such as effective mass and damping are discussed in the context of topological phase transitions.Comment: 20 pages, 15 figure

Feasibility of study magnetic proximity effects in bilayer "superconductor/ferromagnet" using waveguide-enhanced Polarized Neutron Reflectometry

A resonant enhancement of the neutron standing waves is proposed to use in order to increase the magnetic neutron scattering from a "superconductor/ferromagnet"(S/F) bilayer. The model calculations show that usage of this effect allows to increase the magnetic scattering intensity by factor of hundreds. Aspects related to the growth procedure (order of deposition, roughness of the layers etc) as well as experimental conditions (resolution, polarization of the neutron beam, background etc) are also discussed. Collected experimental data for the S/F heterostructure Cu(32nm)/V(40nm)/Fe(1nm)/MgO confirmed the presence of a resonant 60-fold amplification of the magnetic scattering.Comment: The manuscript of the article submitted to Crysstalography Reports. 23 pages, 5 figure

ANALYTICAL SOLUTION OF EQUATIONS SET DESCRIBING DIFFUSION OF POINT DEFECTS IN THE 2-LAYER SEMICONDUCTOR STRUCTURE

The boundary-value problem on impurity and point defect diffusion in the 2-layer semiconductor structure was formulated and analyzed. The analytical solution of the set of equations describing diffusion of intrinsic point defects was obtained for the case of the constant coefficients of these equations. Calculation of the typical distribution of point defects in the 2-layer structure was carried out

PROTECTING COATINGS ON URANIUM

The short state-of-the-art review of the published works, concerning problems of the surface protection of uranium and its alloys from corrosion, mainly, from atmospheric and hydride corrosion is given. Are considered physics and techniques of deposition of antirust coatings by condensation from metals and their alloys plasma, generated by the cathode spot of an arc in vacuum and in tenuous atmosphere of inert and chemically active gases. The analysis of protective properties of coatings of a various composition is carried out. The most effective anticorrosive types of coatings and methods of their formation are revealed

Numerical simulation in roll pass design for bar rolling

The application of finite element simulation to the problem of roll pass design for round bar rolling is considered. Two roll pass sequences were developed by analytical methods and then optimized using 2.5D Finite Element Method (FEM). The first one is a classical oval-round roll pass design. The second one is a combination of flat rolls and round roll passes. Relying on the simulation data obtained by FEM, the roll gaps were adjusted to achieve the required bar shape and the uniform distribution of rolling force between the passes. Advantages and disadvantages of each roll pass design were considered.Web of Science541787

A hydrodynamic model for asymmetric explosions of rapidly rotating collapsing supernovae with a toroidal atmosphere

We numerically solved the two-dimensional axisymmetric hydrodynamic problem of the explosion of a low-mass neutron star in a circular orbit. In the initial conditions, we assumed a nonuniform density distribution in the space surrounding the collapsed iron core in the form of a stationary toroidal atmosphere that was previously predicted analytically and computed numerically. The configuration of the exploded neutron star itself was modeled by a torus with a circular cross section whose central line almost coincided with its circular orbit. Using an equation of state for the stellar matter and the toroidal atmosphere in which the nuclear statistical equilibrium conditions were satisfied, we performed a series of numerical calculations that showed the propagation of a strong divergent shock wave with a total energy of 0.2x10^51 erg at initial explosion energy release of 1.0x10^51 erg. In our calculations, we rigorously took into account the gravitational interaction, including the attraction from a higher-mass (1.9M_solar) neutron star located at the coordinate origin, in accordance with the rotational explosion mechanism for collapsing supernovae.W e compared in detail our results with previous similar results of asymmetric supernova explosion simulations and concluded that we found a lower limit for the total explosion energy.Comment: 13 pages, 5 figures, 2 table

Recovering rearranged cancer chromosomes from karyotype graphs

BACKGROUND: Many cancer genomes are extensively rearranged with highly aberrant chromosomal karyotypes. Structural and copy number variations in cancer genomes can be determined via abnormal mapping of sequenced reads to the reference genome. Recently it became possible to reconcile both of these types of large-scale variations into a karyotype graph representation of the rearranged cancer genomes. Such a representation, however, does not directly describe the linear and/or circular structure of the underlying rearranged cancer chromosomes, thus limiting possible analysis of cancer genomes somatic evolutionary process as well as functional genomic changes brought by the large-scale genome rearrangements. RESULTS: Here we address the aforementioned limitation by introducing a novel methodological framework for recovering rearranged cancer chromosomes from karyotype graphs. For a cancer karyotype graph we formulate an Eulerian Decomposition Problem (EDP) of finding a collection of linear and/or circular rearranged cancer chromosomes that are determined by the graph. We derive and prove computational complexities for several variations of the EDP. We then demonstrate that Eulerian decomposition of the cancer karyotype graphs is not always unique and present the Consistent Contig Covering Problem (CCCP) of recovering unambiguous cancer contigs from the cancer karyotype graph, and describe a novel algorithm CCR capable of solving CCCP in polynomial time. We apply CCR on a prostate cancer dataset and demonstrate that it is capable of consistently recovering large cancer contigs even when underlying cancer genomes are highly rearranged. CONCLUSIONS: CCR can recover rearranged cancer contigs from karyotype graphs thereby addressing existing limitation in inferring chromosomal structures of rearranged cancer genomes and advancing our understanding of both patient/cancer-specific as well as the overall genetic instability in cancer

Development of Requirements for a Basic Standardized Mathematical Model of Geokhod

The article revealed the shortcomings of existing mathematical models geokhods, the necessity of a new approach to modeling the processes of internal and external geokhods interaction, formulated the task of building flexible mathematical models

Zero Liquid Discharge (ZLD) Industrial Wastewater Treatment Systems as Sustainable Development Basic Ecological Components

The problems in processing the acid ferrous-containing rinsing water and spent pickling solutions are considered. The first-ever in metallurgy zero liquid discharge (ZLD) industrial wastewater treatment systems of a transformer cold rolling plant at the Verkh-Isetsky steelworks in Sverdlovsk (now - LLC VIZ Steel is a part of Novolipetsk Steel Group of Companies) is described. The experience of the VIZ Steel, particularly in relation to industrial wastewater treatment and sludge processing, is useful for designing ZLD industrial wastewater treatment systems of metallurgical, machine-building and metalworking enterprises. The recommendations for organizing the ZLD industrial wastewater treatment systems in the pickling plants with the repeated use of the treated rinsing water and processing the spent pickling solutions and the sludges are presented. For practical calculations of clarifiers the empirical formulas are offered. Process flow diagram of acid ferrous-containing rinsing water treatment is suggested. Acid ferrous-containing rinsing water treatment includes the following processes: rinsing water neutralization to pH 9-10,5 by 5 % calcium hydroxide and partial ferrous oxidation by air; addition of anionic flocculant and active gypsum priming to the neutralized rinsing water; settling of rinsing water conditioned by reagents in clarifiers; treatment of clarified water on deep bed sand filters; reclaimed water treatment. © Published under licence by IOP Publishing Ltd