Dialectics of Efficient Change Management in the Regional Social Systems

The research has placed emphasis on the role of the social infrastructure sectors, providing social services, which facilitate human potential development in a modern state. Theoretical positions of the scientist considering the nature of social benefits and necessity of the government support for the social sphere has been summarized in the article. The state of the Russian social infrastructure sectors has been considered and the analysis of their performance compared to these of the social infrastructure sectors in other countries has been conducted in the research work. Taking into consideration the performance ratings of the effectiveness of the national education systems, the countries around the world concerning the effectiveness of the health system, the countries around the world concerning the social development level in 2014, the authors have proposed the conceptual approach that makes it possible to consider the correlation and interrelation of the level of the government financing of the social sphere and the dynamics of the contribution of social infrastructure sectors in the development of the human capital, ensuring the gross domestic product increase. The necessity of making innovative changes in the socio-economic systems of the social infrastructure sectors, to improve their performance, taking into account the results obtained, in the first place, in health care, has been wellgrounded and theoretical approaches to the changes management in the socio-economic systems has been studied in the article. The theoretical approaches to the changes management in the socio-economic systems have been studied by the authors. Based on the conducted studies and the formed theoretical basis for improving the level of changes management in open socio-economic systems, for the purpose of development of the theoretical and methodological approaches to changes management as applied to health care sphere, optimization model of management of health care organizations by way of ranking of manageable and unmanageable changes has been proposed. The possibility of using management optimization by way of ranking of manageable and unmanageable changes in the health care management at different levels has been confirmed with high-performance indicators at the micro-, meso- and macro levels in the sector, by the example of implementation of the national project “Health” and innovative organizational changes facilitating the return to work of patients of the working age, which are involved in the gross domestic product formation in the city of Yekaterinburg.The article has been prepared with the support of the Russian Science Foundation grant No. 14-18-00456 “Support of geoecosocioeconomic approach to development of strategic nature resources capacity of the low-studied northern territories within the investment project “Arctic — Central Asia”

Impurity-induced moments in underdoped cuprates

We examine the effect of a nonmagnetic impurity in a two-dimensional spin liquid in the spin-gap phase, employing a drone-fermion representation of spin-1/2 operators. The properties of the local moment induced in the vicinity of the impurity are investigated and an expression for the nuclear-magnetic- resonance Knight shift is derived, which we compare with experimental results. Introducing a second impurity into the spin liquid an antiferromagnetic interaction between the moments is found when the two impurities are located on different sublattices. The presence of many impurities leads to a screening of this interaction as is shown by means of a coherent-potential approximation. Further, the Kondo screening of an impurity-induced local spin by charge carriers is discussed.Comment: 8 pages, 1 figure. To be published in Phys. Rev. B, Vol. 56, No. 1

The elastic electron-deuteron scattering beyond one-photon exchange

We discuss the elastic ed scattering beyond Born approximation. It is shown that the reaction amplitude contains six generalized form factors, but only three linearly independent combinations of them (we call them generalized charge, quadrupole and magnetic form factors) contribute to the reaction cross section in the second order perturbation theory. We examine two-photon exchange and find that it includes two types of diagrams, when two virtual photons interact with the same nucleon and when the photons interact with different nucleons. Estimations based on nonrelativistic calculations with the deuteron wave function for realistic NN potential show that the main contribution to the generalized charge, quadrupole and magnetic form factors comes from diagrams of the first type.Comment: v2, published version in PR

High-Performance Alkali-Activated Cement Concretes for Marine Engineering Applications

The contribution covers results of studies on the alkali-activated cement concretes intended for marine engineering applications. Such properties as strength, wear, corrosion, freeze-thaw, weather resistance and many others have been studied, and the results are reported and discussed in detail. The obtained results suggested to draw a conclusion on high potential of the alkali-activated cement concretes for marine engineering applications, since in their performance properties these concretes are highly advantageous over other concretes used as marine concretes and big savings can be expected in the future due to the longer span of service life. The results are supported by long-term observations in real conditions. The above advantages are attributed to more perfect micro- and macrostructure of the alkali-activated cement stone. The authors have summarized their own experience and results collected by PhD and DSc students under their supervision dedicated to assessment of durability of these concretes, in particular, for marine engineering applications. In order to bring these advanced materials into practice of construction worldwide, two rilem (International Union of Laboratories and Experts in Construction Materials, Systems and Structures) committees have been founded: “Alkali-activated Materials” (2010–2013) and “Durability Testing of Alkali Activated Materials” (2013–ongoing)

Osteosynthesis of small fragments in multicomminuted fractures of the distal humerus metaepiphysis

The purpose of this study was to improve the treatment results of multicomminued fractures of the distal humerus metaepiphysis through the development of a compression device that provides stable osteosynthesis of small fragments. Materials and methods Clinical testing of the device developed for osteosynthesis of small fragments in multicomminuted fractures of the distal humerus metaepiphysis (patent of Ukraine for useful model #12560) was conducted. Treatment sample included 104 persons with multicomminued fractures of the distal humerus metaepiphysis admitted to the Donetsk national medical university and national trauma center of Donetsk. Results Osteosynthesis of small fragments in multicomminuted metaepiphyseal fractures of the distal humerus with the help of the developed by us compression device enabled to reduce and stabilize small bone fragments, provided the possibility of early movements in the joint and resulted in good outcomes. Conclusions Osteosynthesis of small fragments with application of the developed by us compression device in patients with multicomminued fractures of the distal humerus metaepiphysis showed high efficiency. The mean score was 82.67 ± 5.59 points, which corresponds to good results of treatment

Long-range dynamics of magnetic impurities coupled to a two-dimensional Heisenberg antiferromagnet

We consider a two-dimensional Heisenberg antiferromagnet on a square lattice with weakly coupled impurities, i.e. additional spins interacting with the host magnet by a small dimensionless coupling constant g<<1. Using linear spin-wave theory, we find that the magnetization disturbance at distance r from a single impurity behaves as g/r for 1>1/g. Surprisingly the disturbance is inversely proportional to the coupling constant! The interaction between two impurities separated by a distance r is proportional to g^2/r for 1>1/g. Hence at large distances, the interaction is universal and independent of the coupling constant. We also find that the frequency of Rabi oscillations between two impurities is proportional to g^2 ln(gr) at 1<<r<<1/g, logarithmically enhanced compared to the spin-wave width. This leads to a new mechanism for NMR, NQR and EPR line broadening. All these astonishing results are due to the gapless spectrum of the magnetic excitations in the quantum antiferromagnet.Comment: 6 pages, 5 figure

Analytical approximation for single-impurity Anderson model

We have applied the recently developed dual fermion technique to the spectral properties of single-band Anderson impurity problem (SIAM). In our approach a series expansion is constructed in vertices of the corresponding atomic Hamiltonian problem. This expansion contains a small parameter in two limiting cases: in the weak coupling case ($U/t \to 0$), due to the smallness of the irreducible vertices, and near the atomic limit ($U/t \to \infty$), when bare propagators are small. Reasonable results are obtained also for the most interesting case of strong correlations ($U \approx t$). The atomic problem of the Anderson impurity model has a degenerate ground state, so the application of the perturbation theory is not straightforward. We construct a special approach dealing with symmetry-broken ground state of the renormalized atomic problem. Formulae for the first-order dual diagram correction are obtained analytically in the real-time domain. Most of the Kondo-physics is reproduced: logarithmic contributions to the self energy arise, Kondo-like peak at the Fermi level appears, and the Friedel sum rule is fulfilled. Our approach describes also renormalization of atomic resonances due to hybridization with a conduction band. A generalization of the proposed scheme to a multi-orbital case can be important for the realistic description of correlated solids.Comment: 6 pages, 5 figure

Role of rotational symmetry in the magnetism of a multiorbital model

Effect of rotationally invariant Hund's rule coupling on a magnetism of multiorbital Hubbard models is studied within a dynamical mean-field theory framework. Comparison of static magnetic susceptibilities and local densities of states of two- and three-orbital models of a complete rotationally invariant Coulomb interaction and a "density-density" Hartree type interaction shows the different role of spin-flip interactions for different band fillings. In the particle-hole symmetric case, the Mott-Hubbard physics dominates due to the strong effective Coulomb interaction, while for the multiple electronic configurations away from half-filling (two electrons in the three-band model) the formation of local magnetic moments due to Hund's exchange interaction becomes the most significant effect for itinerant magnetic systems. A shift of the temperature of magnetic ordering due to the rotationally invariant Hund's rule coupling is found to be the largest in a three-orbital model with a two-electron occupancy where the single particle spectrum is metallic and is not sensitive to different forms of the Coulomb vertex. A larger enhancement of the effective mass in a model with a rotationally invariant interaction is discussed. In the half-filled case we find a drastic change in the density of states close to the Mott transition which is related to the spin-flip Kondo fluctuations in a degenerate orbital case, while the corresponding shift of the magnetic transition temperature is relatively small. It is shown that a change in the ground-state degeneracy due to a different symmetry of the Coulomb interaction in the density-density model leads to a breakdown of the quasiparticle peak at the Fermi level in the proximity of a Mott transition on the metallic side. We discuss the relevance of rotationally invariant Hund's interaction in the transition metal magnetism. © 2012 American Physical Society

Quantum spin fluctuations and evolution of electronic structure in cuprates

Correlation effects in CuO$_2$ layers give rise to a complicated landscape of collective excitations in high-T$_{\rm c}$ cuprates. Their description requires an accurate account for electronic fluctuations at a very broad energy range and remains a challenge for the theory. Particularly, there is no conventional explanation of the experimentally observed `resonant' antiferromagnetic mode, which is often considered to be a mediator of superconductivity. Here we model spin excitations of the hole-doped cuprates in the paramagnetic regime and show that this antiferromagnetic mode is associated with electronic transitions between anti-nodal X and Y points of the quasiparticle band that is pinned to the Fermi level. We observe that upon doping of 7-12\% the electronic spectral weight redistribution leads to the formation of a very stable quasiparticle dispersion due to strong correlation effects. The reconstruction of the Fermi surface results in a flattening of the quasiparticle band at the vicinity of the nodal ${\rm M}\Gamma/2$ point, accompanied by a high density of charge carriers. Collective excitations of electrons between the nodal ${\rm M}\Gamma/2$ and ${\rm XM}/2$ points form the additional magnetic holes state in magnetic spectrum, which protects the antiferromagnetic fluctuation. Further investigation of the evolution of spin fluctuations with the temperature and doping allowed us to observe the incipience of the antiferromagnetic ordering already in the paramagnetic regime above the transition temperature. Additionally, apart from the most intensive low-energy magnetic excitations, the magnetic spectrum reveals less intensive collective spin fluctuations that correspond to electronic processes between peaks of the single-particle spectral function