83 research outputs found
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 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
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)
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