Gauge Topological Nature of the Superconductor-Insulator Transition

It has long been believed that, at absolute zero, electrons can form only one quantum coherent state, a superconductor. Yet, several two dimensional superconducting systems were found to harbor the superinsulating state with infinite resistance, a mirror image of superconductivity, and a metallic state often referred to as Bose metal, characterized by finite longitudinal and vanishing Hall resistances. The nature of these novel and mysterious quantum coherent states is the subject of intense study.Here, we propose a topological gauge description of the superconductor-insulator transition (SIT) that enables us to identify the underlying mechanism of superinsulation as Polyakov's linear confinement of Cooper pairs via instantons. We find a criterion defining conditions for either a direct SIT or for the SIT via the intermediate Bose metal and demonstrate that this Bose metal phase is a Mott topological insulator in which the Cooper pair-vortex liquid is frozen by Aharonov-Bohm interactions

High-Symmetry Polarization Domains in Low-Symmetry Ferroelectrics

We present experimental evidence for hexagonal domain faceting in the ferroelectric polymer PVDF-TrFE films having the lower orthorhombic crystallographic symmetry. This effect can arise from purely electrostatic depolarizing forces. We show that in contrast to magnetic bubble shape domains where such type of deformation instability has a predominantly elliptical character, the emergence of more symmetrical circular harmonics is favored in ferroelectrics with high dielectric constant

Landau thermodynamic potential for BaTiO_3

In the paper, the description of the dielectric and ferroelectric properties of BaTiO_3 single crystals using Landau thermodynamic potential is addressed. Our results suggest that when using the sixth-power free energy expansion of the thermodynamic potential, remarkably different values of the fourth-power coefficient, \beta (the coefficient of P^4_i terms), are required to adequately reproduce the nonlinear dielectric behavior of the paraelectric phase and the electric field induced ferroelectric phase, respectively. In contrast, the eighth-power expansion with a common set of coefficients enables a good description for both phases at the same time. These features, together with the data available in literature, strongly attest to the necessity of the eighth-power terms in Landau thermodynamic potential of BaTiO_3. In addition, the fourth-power coefficients, \beta and \xi (the coefficient of P^2_i P^2_j terms), were evaluated from the nonlinear dielectric responses along [001], [011], and [111] orientations in the paraelectric phase. Appreciable temperature dependence was evidenced for both coefficients above T_C. Further analysis on the linear dielectric response of the single domain crystal in the tetragonal phase demonstrated that temperature dependent anharmonic coefficients are also necessary for an adequate description of the dielectric behavior in the ferroelectric phase. As a consequence, an eighth-power thermodynamic potential, with some of the anharmonic coefficients being temperature dependent, was proposed and compared with the existing potentials. In general, the potential proposed in this work exhibits a higher quality in reproducing the dielectric and ferroelectric properties of this prototypic ferroelectric substance.Comment: 7 figures, 5 table

Electro-absorption of silicene and bilayer graphene quantum dots

We study numerically the optical properties of low-buckled silicene and AB-stacked bilayer graphene quantum dots subjected to an external electric field, which is normal to their surface. Within the tight-binding model, the optical absorption is calculated for quantum dots, of triangular and hexagonal shapes, with zigzag and armchair edge terminations. We show that in triangular silicene clusters with zigzag edges a rich and widely tunable infrared absorption peak structure originates from transitions involving zero energy states. The edge of absorption in silicene quantum dots undergoes red shift in the external electric field for triangular clusters, whereas blue shift takes place for hexagonal ones. In small clusters of bilayer graphene with zigzag edges the edge of absorption undergoes blue/red shift for triangular/hexagonal geometry. In armchair clusters of silicene blue shift of the absorption edge takes place for both cluster shapes, while red shift is inherent for both shapes of the bilayer graphene quantum dots.Comment: 7 pages, 7 figure

Fractional-flux vortices and spin superfluidity in triplet superconductors

We discuss a novel type of fractional flux vortices along with integer flux vortices in Kosterlitz-Thouless transitions in a triplet superconductor. We show that under certain conditions a spin-triplet superconductor should exhibit a novel state of {\it spin superfluidity} without superconductivity.Comment: Physical Review Lettes, in print. v2: references added, v3: discussion of several points extended according to referee request. Latest updates and links to related papers are available at my homepage http://people.ccmr.cornell.edu/~egor

Upper critical field in layered superconductors

The theoretical statements about a restoration of a superconductivity at magnetic fields higher than the quasiclassical upper critical field and a reentrance of superconductivity at temperatures $T_c(H)\approx T_c(0)$ in the superconductors with open Fermi surfaces are reinvestigated taking into account a scattering of quasiparticles on the impurities. The system of integral equations for determination of the upper critical field parallel to the conducting planes in a layered conventional and unconventional superconductors with impurities are derived. The $H_{c2}(T)$ values for the "clean" case in the Ginzburg-Landau regime and at any temperature in the "dirty" case are found analytically. The upper limit of the superconductor purity when the upper critical field definately has a finite value is established.Comment: 10 page

Plasticity of an extra-strong nanocrystalline stainless steel controlled by the "dislocation-segregation'' interaction

We study three structurally different states of nanocrystalline 316 steel and show that the state, where boundaries containing excess concentration of alloying elements are combined with mobile dislocations in grain interiors, allows maintaining extraordinarily high strength and remarkably enhanced plasticity. Underlying mechanisms featuring interaction between the segregations and mobile dislocations are discussed

Molecular genetic characteristics of gastric cancers from the surgeon’s point of view

Dubinina V. G., Mashukov A. A., Lukyanchuk O. V., Bilenko A. A., Zgura A. N., Raciborsky D. V., Lee S. N. Molecular genetic characteristics of gastric cancers from the surgeon’s point of view. Journal of Education, Health and Sport. 2016;6(11):592-621. eISSN 2391-8306. DOI http://dx.doi.org/10.5281/zenodo.200394 http://ojs.ukw.edu.pl/index.php/johs/article/view/4063 The journal has had 7 points in Ministry of Science and Higher Education parametric evaluation. Part B item 755 (23.12.2015). 755 Journal of Education, Health and Sport eISSN 2391-8306 7 © The Author (s) 2016; This article is published with open access at Licensee Open Journal Systems of Kazimierz Wielki University in Bydgoszcz, Poland Open Access. This article is distributed under the terms of the Creative Commons Attribution Noncommercial License which permits any noncommercial use, distribution, and reproduction in any medium, provided the original author(s) and source are credited. This is an open access article licensed under the terms of the Creative Commons Attribution Non Commercial License (http://creativecommons.org/licenses/by-nc/4.0/) which permits unrestricted, non commercial use, distribution and reproduction in any medium, provided the work is properly cited. This is an open access article licensed under the terms of the Creative Commons Attribution Non Commercial License (http://creativecommons.org/licenses/by-nc/4.0/) which permits unrestricted, non commercial use, distribution and reproduction in any medium, provided the work is properly cited. The authors declare that there is no conflict of interests regarding the publication of this paper. Received: 02.11.2016. Revised 22.11.2016. Accepted: 30.11.2016. MOLECULAR GENETIC CHARACTERISTICS OF GASTRIC CANCERS FROM THE SURGEON’S POINT OF VIEW V. G. Dubinina1, A. A. Mashukov2, O. V. Lukyanchuk2, A. A. Bilenko1, A. N. Zgura2, D. V. Raciborsky2, S. N. Lee2 1Odessa National Medical university 2Odessa Regional Oncology center Summary A study on the expression of oncoproteins in stomach` carcinomas, has been turned into a real research basically due to the abundance of results and their comprehensive interpretations. The study carried out on the abdominal onco-surgical department of Odessa Regional Oncology Center, included a study of 188 patients operated on for gastric cancer (GC) between 2007-2011. In all cases was performed the so-called lymphadenectomy for the principal reason of extensive preventive biopsy of visually unchanged lymph nodes. We spend a multivariate analysis of interactions between the expression of oncoproteins p53, VEGFR-3, erbB2, Ki67 and micro involvement of tumor vasculature (ly, v), the local growth (T), the presence of residual tumor tissue (the R), the degree of tumor differentiation (the G) the degree of regional lymph nodes involvement (N) and type of infiltration (Inf α, β, Inf Υ). Keywords: Stomach cancer, Immunohistochemistry and Oncoproteins

Some novel ways of gastric cancer patients treatment personification

In this paper the authors perform the analysis of molecular and morphological factors influencing the survival of patients with gastric cancer (n = 221). They analyzed the survival rate in this group of patients based on the analysis of molecular markers VEGFR, p53, Her2, Ki-67. Measured role in the survival such factors as the degree of differentiation of primary gastric tumors, the presence of microscopic tumor involvement of perineural and perivascular spaces, the degree of invasion to gastric wall by T1 = 1 and to T4a = 4, T4b = 5, number of regional lymph nodes affected by metastasis, and other factors. As an arbitrator used survival curves calculated by the method of R. J. Cox, time of lifespan, measured in months, as well as a comparison of the areas under the curves of survival