On the hyperfine interaction in rare-earth Van Vleck paramagnets at high magnetic fields

An influence of high magnetic fields on hyperfine interaction in the rare-earth ions with non-magnetic ground state (Van Vleck ions) is theoretically investigated for the case of $Tm^{3+}$ ion in axial symmetrical crystal electric field (ethylsulphate crystal). It is shown that magnetic-field induced distortions of $4f$-electron shell lead to essential changes in hyperfine magnetic field at the nucleus. The proposed theoretical model is in agreement with recent experimental data.Comment: 4 pages, no figures, submitted to J. Phys. : Cond. Mat

Temperature dependence of the EPR linewidth of Yb3+ - ions in Y0.99Yb0.01Ba2Cu3OX compounds: Evidence for an anomaly near TC

Electron paramagnetic resonance experiments on doped Yb3+ ions in YBaCuO compounds with different oxygen contents have been made. We have observed the strong temperature dependence of the EPR linewidth in the all investigated samples caused by the Raman processes of spin-lattice relaxation. The spin-lattice relaxation rate anomaly revealed near TC in the superconducting species can be assigned to the phonon density spectrum changesComment: 10 pages, 4 figures Renewed versio

A geometric interpretation of the spectral parameter for surfaces of constant mean curvature

Considering the kinematics of the moving frame associated with a constant mean curvature surface immersed in S^3 we derive a linear problem with the spectral parameter corresponding to elliptic sinh-Gordon equation. The spectral parameter is related to the radius R of the sphere S^3. The application of the Sym formula to this linear problem yields constant mean curvature surfaces in E^3. Independently, we show that the Sym formula itself can be derived by an appropriate limiting process R -> infinity.Comment: 12 page

EPR imaging study of paramagnetic centre distribution in thiokol-epoxy hermetics

The distribution of paramagnetic centres in carbon black filler in the interphase layer of the thiokol-epoxy hermetics on the border of brass or glass substrate was studied using EPR-imaging method. It was shown that the relative content of radicals decreases near the hermetic-"rigid" surface contact border. The thickness of the layer with a low concentration of radicals is estimated as 0.5±0.3 mm. The inhomogeneous distribution of radicals is more obvious in the case of hermetic hardening on a brass surface. These results are explained by a catalytic acceleration of the thiokol-epoxy polymerization reaction in the region of hermetic-metal surface contact. © 1996 Springer

Stabilization of test particles in Induced Matter Kaluza-Klein theory

The stability conditions for the motion of classical test particles in an $n$-dimensional Induced Matter Kaluza-Klein theory is studied. We show that stabilization requires a variance of the strong energy condition for the induced matter to hold and that it is related to the hierarchy problem. Stabilization of test particles in a FRW universe is also discussed.Comment: 15 pages, 1 figure, to appear in Class. Quantum Gra

Multidrug-resistance and presence of class 1 integrons in clinical isolates of Salmonella enterica serotype Enteritidis, circulating in Armenia

Abstract. The aim of this work was detection of class 1 integrons and their contribution to the antimicrobial resistance phenotypes in strains of   subspecies enterica serotype Enteritidis. S. Enteritidis strains (n = 29) were isolated from patients with salmonellosis at “Nork” Clinical Hospital of Infectious Diseases, Yerevan, Republic of Armenia. High prevalence of multi-drug resistance (MDR) phenotypes was revealed and isolates with MDR phenotypes which are rare in the S. Enteritidis serotype were observed. Class 1 integrons were detected in 27,6% of isolates, with the prevalence of a variable region of 1000 bp. Occurrence of the MDR phenotype was more frequent in integron-positive isolates compared to integron-negative isolates of S. Enteritidis. Further studies are necessary to reveal the genetic background of MDR phenotypes and to estimate the genetic kinship among the isolates. Our results suggest a rapid and large-scale penetration of antibiotic resistance genes into populations of S. Enteritidis, which complicates infection control. More rigorous regulations should be imposed on antibiotic use, together with a vigilant epidemiological surveillance, to prevent the emergence and spread of MDR S. Enteritidis

Multidimensional Toda type systems

On the base of Lie algebraic and differential geometry methods, a wide class of multidimensional nonlinear systems is obtained, and the integration scheme for such equations is proposed.Comment: 29 pages, LaTeX fil

Our experience with mitral valve repair using an autologous pericardium for recurrent mitral regurgitation

Objective: To present outcomes of mitral valve reinterventions for recurrent degenerative mitral regurgitation.Materials and methods: From May 2017 to February 2021 3 male patients aged 43, 50, and 54 years and an 18-year-old female patient underwent mitral valve reinterventions with an autopericardial strip at Scientific Research Institute – Specialized Cardiac Surgery Clinical Hospital named after Academician B.A. Korolev. Three patients had primary mitral valve annuloplasty using a support ring and 1 patient using an autopericardial strip. In this patient group recurrent mitral regurgitation developed within 6-33 months between the primary repair and reintervention (20 ± 13.5 months on average).Results: No hospital mortality was reported. Cardiopulmonary bypass duration averaged 109.8 ± 19.7 minutes, and myocardial ischemia lasted 77.5 ± 10.1 minutes. Two patients had an adjunctive repeat radiofrequency Maze procedure, with the supraventricular rhythm restored in 1 patient. Echocardiography demonstrated that mitral regurgitation did not exceed grade 1 at discharge. Reintervention using an autopericardial strip for recurrent mitral regurgitation significantly reduces sizes of the left atrium and left ventricle. Ejection fraction did not change after the intervention. Mitral valve peak gradient in all cases did not exceed 9 mm Hg.Conclusions: The key to a successful mitral valve reintervention is a qualitative analysis of the recurrence causes and use of various techniques and materials for intervention on the mitral valvular complex. Mitral valve reinterventions, especially in young patients, are justified if certain safety conditions are met and have similar outcomes to primary interventions