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

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

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

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

ON THE STATE OF ENDOTHELIAL DESQUAMATION IN CANCER PATIENTS

Lukyanchuk O. V., Moskalenko A. M., Bokal I. I., Gozhenko A. I. ON THE STATE OF ENDOTHELIAL DESQUAMATION IN CANCER PATIENTS. Актуальні проблеми транспортної медицини / Actual problems of transport medicine / 2018;4(54):88-93. ISSN 1818-9385 DOI http://dx.doi.org/10.5281/zenodo.2525619 http://aptm.org.ua ON THE STATE OF ENDOTHELIAL DESQUAMATION IN CANCER PATIENTS O. V. Lukyanchuk1, A. M. Moskalenko1, I. I. Bokal1, A. I. Gozhenko2 1Odessa Regional Oncology Center 2SE “Research Institute for Medicine of Transport of the Ministry of Health Care of Ukraine”, Odessa Abstract Introduction. Hypercoagulation is one of the most important general changes in the body of cancer patients, the presence of which is taken into account both in the surgical and conservative treatment of cancer patients and requires adequate correction due to the possibility of thrombotic complications. The objective. To study the number of circulating endotheliocytes (CE) and assess the extent of endothelial damage in cancer patients before and after treatment with dacarbazine. Materials and research methods. The content of CE in 20 cancer patients before and after treatment with dacarbazine was studied. Dacarbazine was administered intravenously once at a dosage of 60-75 mg / m2 of a body surface. At 1-3 days after its introduction, a complete blood count, urinalysis, coagulogram were examined in the patients under observation. Results. A high content of CE at all the patients under observation was established. Chemotherapy is accompanied by an increase in CE content for more than twice. Conclusion. The tumor process increases desquamation of endothelium, which increases even more after chemotherapy. Key words: endothelial desquamation, hypercoagulation, circulating endotheliocytes, cancer patients, dacarbazine

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

Polymorphism of the <i>Rca2</i> anthracnose resistance gene in strawberry cultivars (<i>Fragaria × ananassa</i>)

Background. Anthracnose, caused by phytopathogenic fungi of the genus Colletotrichum, is one of the most important strawberry diseases. Strawberry yield losses from anthracnose lesions can reach 80%. Most strawberry cultivars are susceptible to anthracnose. Therefore, identification of the initial forms carrying resistance genes is a necessary step toward successful breeding of anthracnose-resistant cultivars. Use of molecular markers will increase reliability of identification and enhance effectiveness of strawberry breeding.Materials and methods. Biological material was represented by strawberry cultivars (Fragaria × ananassa Duch.) of various ecological and geographical origin. Total genomic DNA was extracted from the fresh leaves using the CTAB methods according to Puchooa (2004). To assess the allelic state of the Rca2 anthracnose resistance gene, the SCAR marker STS-Rca2_240 was used. The SCAR marker STS-Rca2_240 was multiplexed with the microsatellite marker EMFv020 used as the positive PCR control.Results and conclusion. The SCAR marker STS-Rca2_240, mapping at about 2.8 cM from the Rca2 gene, was identified in the strawberry cultivars ‘Elianny’, ‘Troubadour’ and ‘Sudarushka’. Cvs. ‘Elianny’ and ‘Troubadour’ are presumably characterized by a dominant homozygous (Rca2Rca2) or heterozygous (Rca2rca2) genotype. Cv. ‘Sudarushka’ has the heterozygous state for the Rca2 anthracnose resistance gene (Rca2rca2). In the remaining cultivars studied, the marker STS-Rca2_240 was not detected (the prospective genotype is rca2rca2)