Effect of epitaxial strain on the electronic structure and magnetic correlations in infinite-layer (Nd,Sr)NiO2_2

We present a theoretical study of the effect of electron-electron interactions and Sr doping on the electronic structure of infinite-layer (Nd,Sr)NiO$_2$ using the density functional+dynamical mean-field theory approach. In particular, we explore the impact of epitaxial compressive strain that experience (Nd,Sr)NiO$_2$ films on the electronic properties, magnetic correlations, and exchange couplings. Our results reveal the crucial importance of orbital-dependent correlation effects in the Ni $3d$ shell of Sr-doped NdNiO$_2$. Upon doping with Sr, it undergoes a Lifshitz transition which is accompanied by a reconstruction of magnetic correlations: For Sr $x<0.2$ (Nd,Sr)NiO$_2$ adopts the N\'eel $(111)$ antiferromagnetic (AFM) order, while for $x>0.2$ the $C$-type $(110)$ AFM sets in the unstrained (Nd,Sr)NiO$_2$, with a highly frustrated region at $x \simeq 0.2$, all within DFT+DMFT at $T=290$ K. Our results for the N\'eel AFM at Sr $x=0$ suggest that AFM NdNiO$_2$ appears at the verge of a Mott-Hubbard transition, providing a plausible explanation for the experimentally observed weakly insulating behavior of NdNiO$_2$ for Sr $x<0.1$. We observe that the Lifshitz transition makes a change of the band structure character from electron- to hole-like with Sr $x$, in agreement with recent experiments. Our results for magnetic couplings demonstrate an unanticipated frustration of the Ni $3d$ magnetic moments, which suppresses magnetic order near Sr $x=0.2$. We find that the effect of frustration is maximal for Sr doping $x \simeq 0.1-0.2$ that nearly corresponds to the experimentally observed doping value. We conclude that the in-plane strain adjusts a bandwidth of the Ni $x^2-y^2$ band, i.e., controls the effect of electron correlations in the Ni $x^2-y^2$ orbitals. The electronic properties of (Nd,Sr)NiO$_2$ reveal an anomalous sensitivity upon a change of the crystal structure parameters.Comment: 11 pages, 9 figures; the crystal structure used is under question; this may affect the resul

Hidden attractors in fundamental problems and engineering models

Recently a concept of self-excited and hidden attractors was suggested: an attractor is called a self-excited attractor if its basin of attraction overlaps with neighborhood of an equilibrium, otherwise it is called a hidden attractor. For example, hidden attractors are attractors in systems with no equilibria or with only one stable equilibrium (a special case of multistability and coexistence of attractors). While coexisting self-excited attractors can be found using the standard computational procedure, there is no standard way of predicting the existence or coexistence of hidden attractors in a system. In this plenary survey lecture the concept of self-excited and hidden attractors is discussed, and various corresponding examples of self-excited and hidden attractors are considered

EVALUATION OF SUBMERGED HEALING OF COLONIC ANASTOMOSES IN SURGICAL HOSPITAL

Thus, the main causes of «hand technique» anastomosis by invagination are technical defects of the intervention in telescopic anastomosis by invagination and the ischemic disorders in colorectal anastomosis by invagination. 48 patients were operated on the colon and rectum with «hand technique» anastomosis. Invalidated «manual technique» anastomosis after 70 days of the formation were fully functional, and processes of healing and morphological transformation of mucosa were completed

General Scheme of Risk – Oriented Audit Stages

The article examines the problem of applying risk-oriented approach in audit. A risk-oriented approach on the one hand allows to increase efficiency of auditors’ activity, the level of compliance with mandatory requirements, and on the other hand, to avoid the excessive inspections’ procedures in the formation of a scientifically grounded framework of reasonable sufficiency inherent to each specific audit. At the same time, risk-oriented approach needs to create its own methodological base, develop methodologies and relevant accompanying documents, and, most importantly, train personnel capable of implementing this innovative methodology. For this reason, topic of this paper is extremely relevant. &nbsp; &nbsp; Keywords: audit, risk-oriented approach, planning, accounting (financial) statement

Algorithmic decidability of Engel's property for automaton groups

We consider decidability problems associated with Engel's identity ($[\cdots[[x,y],y],\dots,y]=1$ for a long enough commutator sequence) in groups generated by an automaton. We give a partial algorithm that decides, given $x,y$, whether an Engel identity is satisfied. It succeeds, importantly, in proving that Grigorchuk's $2$-group is not Engel. We consider next the problem of recognizing Engel elements, namely elements $y$ such that the map $x\mapsto[x,y]$ attracts to $\{1\}$. Although this problem seems intractable in general, we prove that it is decidable for Grigorchuk's group: Engel elements are precisely those of order at most $2$. Our computations were implemented using the package FR within the computer algebra system GAP

Rules of Internal Control of the Broker as a Tool for Risk Management of ML/FT

The article analyzes and identifies the features of a brokerage company as an economic entity, identifies the main risks of a broker in the sphere of ML/FT, and examines the rules of internal control and the requirements imposed on them. &nbsp; &nbsp; Keywords: internal control, broker, risks, economic securit

The Use of Analytical Tools in the Conduct of Internal Control Procedures

The work is devoted to the study of the problems of management, the activities of international companies in solving urgent problems of risk assessment, international cooperation of companies in the development and use of software and the applications of the Business Intelligence class, Data Quality and Business Analytics, the role of SAS in the domestic market. The first part is devoted to the activities of international companies in the field of risk assessment. The second part is devoted to the review of analytical products of SAS. &nbsp; Keywords: audit, risk assessment, in-depth analytics, business intelligenc