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Search Results: 1 - 10 of 404891 matches for " Boris M. Kataev "
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Contribution to knowledge of the genus Chydaeus in Xizang Autonomous Region (Tibet) and Yunnan Province, China (Coleoptera, Carabidae, Harpalini)
Boris M. Kataev,Hongbin Liang,David Kavanaugh
ZooKeys , 2012, DOI: 10.3897/zookeys.171.2306
Abstract: Five new species of the genus Chydaeus Chaudoir, 1854 are described from China: C. fugongensis sp. n. (Shibali, Fugong County, Yunnan Province), C. gutangensis sp. n. (Gutang, Medog County, Xizang Autonomous Region [Tibet]), C. hanmiensis sp. n. (Hanmi, Medog County, Xizang Autonomous Region [Tibet]), C. asetosus sp. n. (NE of Fugong, Yunnan Province), and C. baoshanensis sp. n. (N of Baoshan, Yunnan Province). Taxonomic and faunistic notes on eleven other species occurring in Xizang and Yunnan are also provided. Chydaeus shunichii Ito, 2006 is re-described, based on specimens from Lushui County, Yunnan. Chydaeus kumei Ito, 1992 is treated as a subspecies of C. andrewesi Schauberger, 1932 [NEW STATUS]. The taxonomic status of C. guangxiensis Ito, 2006 is discussed. The following taxa are recorded from China for the first time: C. obtusicollis Schauberger, 1932 (Xizang and Yunnan), C. malaisei Kataev & Schmidt, 2006 (Yunnan), C. semenowi (Tschitschérine, 1899) (Xizang and Yunnan), C. andrewesi andrewesi Schauberger, 1932 (Xizang and Yunnan), C. andrewesi kumei Ito (Yunnan), C. bedeli interjectus Kataev & Schmidt, 2002 (Xizang), and C. bedeli vietnamensis Kataev & Schmidt, 2002 (Yunnan).
Slow antiferromagnetic dynamics in the low temperature tetragonal phase of La_{2-x}Sr_xCuO_4 as revealed by ESR of Gd spin probes
V. Kataev,B. Rameev,B. Buechner,M. Huecker,R. Borowski
Physics , 1996, DOI: 10.1103/PhysRevB.55.R3394
Abstract: Measuring the ESR of Gd spin probes we have studied the magnetic properties of the copper oxide planes in the low temperature tetragonal (LTT) phase of Eu doped La_{2-x}Sr_xCuO_4. The data give evidence that at particular levels of Sr and Eu doping the frequency of the antiferromagnetic fluctuations in the LTT phase dramatically decreases at low temperatures by almost three orders of magnitude. However, no static magnetic order has been found for T>8K in contrast to the observation by neutron scattering of stripe ordering of spins below 50K in a Nd doped La_{2-x}Sr_xCuO_4 single crystal. To our opinion static order in the Nd doped compound is induced due to the interaction between the Cu spins with the rare earth magnetic moments. Therefore, a really characteristic property of the magnetism in the LTT structural phase may be not static magnetic order at elevated temperatures but rather extremely slow antiferromagnetic dynamics.
Magnetism of the LTT phase of Eu doped La_{2-x}Sr_xCuO_4
M. Huecker,J. Pommer,B. Buechner,V. Kataev,B. Rameev
Physics , 1997, DOI: 10.1007/BF02765736
Abstract: The ESR signal of Gd spin probes (0.5 at %) as well as the static normal state susceptibility of Eu (J(Eu^{3+})=0) doped La_{2-x-y}Sr_xEu_yCuO_4 reveal pronounced changes of the Cu magnetism at the structural transition from the orthorhombic to the low temperature tetragonal phase for all non-superconducting compositions. Both a jumplike decrease of \chi as well as the ESR data show an increase of the in-plane magnetic correlation length in the LTT phase. From the Gd^{3+} ESR linewidth we find that for specific Eu and Sr concentrations in the LTT phase the correlation length increases up to more than 100 lattice constants and the fluctuation frequency of the CuO_2 spin system slows down to 10^{10}- 10^{11}sec^{-1}. However, there is no static order above T ~ 8K in contrast to the LTT phase of Nd doped La_{2-x}Sr_xCuO_4 with pinned stripe correlations.
Strong enhancement of spin fluctuations in the low-temperature-tetragonal phase of antiferromagnetically ordered La_{2-x-y}Eu_ySr_xCuO_4
V. Kataev,A. Validov,M. Huecker,H. Berg,B. Buechner
Physics , 1999, DOI: 10.1088/0953-8984/11/34/309
Abstract: Measurements of the static magnetization, susceptibility and ESR of Gd spin probes have been performed to study the properties of antiferromagnetically ordered La_{2-x-y}Eu_ySr_xCuO_4 (x less or equal 0.02) with the low temperature tetragonal structure. According to the static magnetic measurements the CuO_2 planes are magnetically decoupled in this structural phase. The ESR study reveals strong magnetic fluctuations at the ESR frequency which are not present in the orthorhombic phase. It is argued that this drastic enhancement of the spin fluctuations is due to a considerable weakening of the interlayer exchange and a pronounced influence of hole motion on the antiferromagnetic properties of lightly hole doped La_2CuO_4. No evidence for the stripe phase formation at small hole doping is obtained in the present study.
Relevance of communications at sale points in the modern concept of merchandising
Andrey Kataev
Path of Science , 2016, DOI: 10.22178/pos.13-5
Abstract: Owners of brands spend a large amount of money to promote their products. However, communication at sale points usually does not meet the overall strategy of integrated marketing communication as communication and sales are the question of competence of different managers. If not to pay proper attention to this question today, thousands of advertising budgets, PR and other campaigns will not bring effect under conditions of inconsistent sales strategies and tactics. The article gives the theoretical grounding of integration of communications at sale points into the structure of retail marketing communications.
Dzyaloshinsky-Moriya Spin Canting in the LTT Phase of La2-x-yEuySrxCuO4
M. Huecker,V. Kataev,J. Pommer,U. Ammerahl,A. Revcolevschi,J. M. Tranquada,B. Buechner
Physics , 2003, DOI: 10.1103/PhysRevB.70.214515
Abstract: The Cu spin magnetism in La2-x-yEuySrxCuO4 (x<=0.17; y<=0.2) has been studied by means of magnetization measurements up to 14 T. Our results clearly show that in the antiferromagnetic phase Dzyaloshinsky-Moriya (DM)superexchange causes Cu spin canting not only in the LTO phase but also in the LTLO and LTT phases. In La1.8Eu0.2CuO4 the canted DM-moment is about 50% larger than in pure La2CuO4 which we attribute to the larger octahedral tilt angle. We also find clear evidence that the size of the DM-moment does not change significantly at the structural transition at T_LT from LTO to LTLO and LTT. The most important change induced by the transition is a significant reduction of the magnetic coupling between the CuO2 planes. As a consequence, the spin-flip transition of the canted Cu spins which is observed in the LTO phase for magnetic field perpendicular to the CuO2 planes disappears in the LTT phase. The shape of the magnetization curves changes from the well known spin-flip type to a weak-ferromagnet type. However, no spontaneous weak ferromagnetism is observed even at very low temperatures, which seems to indicate that the interlayer decoupling in our samples is not perfect. Nonetheless, a small fraction (<15%) of the DM-moments can be remanently magnetized throughout the entire antiferromagnetically ordered LTT/LTLO phase, i.e. for T
Preferential antiferromagnetic coupling of vacancies in graphene on SiO_2: Electron spin resonance and scanning tunneling spectroscopy
S. Just,S. Zimmermann,V. Kataev,B. Buechner,M. Pratzer,M. Morgenstern
Physics , 2014, DOI: 10.1103/PhysRevB.90.125449
Abstract: Monolayer graphene grown by chemical vapor deposition and transferred to SiO_2 is used to introduce vacancies by Ar^+ ion bombardment at a kinetic energy of 50 eV. The density of defects visible in scanning tunneling microscopy (STM) is considerably lower than the ion fluence implying that most of the defects are single vacancies. The vacancies are characterized by scanning tunneling spectroscopy (STS) on graphene and HOPG exhibiting a peak close to the Fermi level. The peak persists after air exposure up to 180 min, albeit getting broader. After air exposure for less than 60 min, electron spin resonance (ESR) at 9.6 GHz is performed. For an ion flux of 10/nm^2, we find a signal corresponding to a g-factor of 2.001-2.003 and a spin density of 1-2 spins/nm^2. The ESR signal consists of a mixture of a Gaussian and a Lorentzian of equal weight exhibiting a width down to 0.17 mT, which, however, depends on details of the sample preparation. The g-factor anisotropy is about 0.02%. Temperature dependent measurements reveal antiferromagnetic correlations with a Curie-Weiss temperature of -10 K. Albeit the electrical conductivity of graphene is significantly reduced by ion bombardment, the spin resonance induced change in conductivity is below 10^{-5}.
Contact Lie algebras of vector fields on the plane
Boris M. Doubrov,Boris P. Komrakov
Mathematics , 1999, DOI: 10.2140/gt.1999.3.1
Abstract: The paper is devoted to the complete classification of all real Lie algebras of contact vector fields on the first jet space of one-dimensional submanifolds in the plane. This completes Sophus Lie's classification of all possible Lie algebras of contact symmetries for ordinary differential equations. As a main tool we use the abstract theory of filtered and graded Lie algebras. We also describe all differential and integral invariants of new Lie algebras found in the paper and discuss the infinite-dimensional case.
Subsemigroups of inverse semigroups
Boris M. Schein
Le Matematiche , 1996,
Abstract: See directly the article.
Annihilation Catastrophe: From Formation to Universal Explosion
Boris M. Shipilevsky
Physics , 2005,
Abstract: I present a systematic analysis of formation of the universal annihilation catastrophe which develops in an open system, where species $A$ and $B$ diffuse from the bulk of restricted medium and die on its surface (desorb) by the reaction $A + B \to 0$. This phenomenon arises in the diffusion-controlled limit as a result of self-organizing explosive growth (drop) of the surface concentrations of, respectively, slow and fast particles ({\it concentration explosion}) and manifests itself in the form of an abrupt singular jump of the desorption flux relaxation rate. As striking results I find the dependences of time and amplitude of the catastrophe on the initial particle number, and answer the basic questions of when and how universality is achieved.
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