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On the Seneta Sequences

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Acta Mathematica Sinica,English Series 2006年第3期22卷 689-692页

作者： Dragan DJURI Aleksandar TORGAev Technical Faculty Svetog Save 6532000 aakSerbia and Montenegro Faculty of Mathematics Studentski trg 16a11000 BeogradSerbia and Montenegro

In this paper, we prove some properties of the Seneta sequences and functions, and in particular we prove a representation theorem in the Karamata sense for the sequences from the Seneta class SOc.

关键词： Regularly varying functions and sequences Seneta functions and sequences Representation theorem

On a Question of the Theory of Partially Composition Formations（Dedicated to Professor K.P. Shum on the occasion of his 70th birthday）

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Algebra Colloquium 2014年第3期21卷 437-447页

作者： A.A. Tsarev N.N. Vorob'ev Department of Mathematics P.M. Masherov Vitebsk State University Vitebsk 210038 Belarus Department of Mathematics F. Skorina Gomel State University Gomel' 246019 Belarus

Let n 〉 0 and w be a non-empty set of primes. It is proved that the lattice of all τ-closed n-multiply ω-composition formations is inductive. It gives a positive answer to a question of Skiba asked in 2001 at the G... 详细信息

关键词： finite group formation of groups ω-composition satellite of formation,τ -closed n-multiply ω-composition formation inductive lattice of formations

Numerical simulations of three-dimensional magnetic swirls in a solar flux-tube

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Research in Astronomy and Astrophysics 2014年第7期14卷 855-863页

作者： Piotr Chmielewski Krzysztof Murawski Alexandr A.Solov’ev Group of Astrophysics University of Maria Curie-Sk?odowskaul.Radziszewskiego 1020-031 LublinPoland Pulkovo Astronomical Observatory Pulkovskoe shosse 65/1 196140Saint PetersburgRussian Federation

We aim to numerically study evolution of Alfv′en waves that accompany short-lasting swirl events in a solar magnetic flux-tube that can be a simple model of a magnetic pore or a sunspot. With the use of the FLASH code we numerically solve three-dimensional ideal magnetohydrodynamic equations to simulate twists which are implemented at the top of the photosphere in magnetic field lines of the flux-tube. Our numerical results exhibit swirl events and Alfv′en waves with associated clockwise and counterclockwise rotation of magnetic lines, with the largest values of vorticity at the bottom of the chromosphere, and a certain amount of energy flux.

关键词： MHD -- Sun: magnetic fields -- Alfven waves propagation

Effect of yttrium on photosynthesis and water relations in young maize plants

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Journal of Rare Earths 2014年第4期32卷 371-378页

作者： Ivana Maksimovi Rudolf Kastori Marina Putnik-Deli Milan Boriev Faculty of Agriculture University of Novi Sad Department of Biology and Ecology Faculty of SciencesUniversity of Novi Sad

Despite an increase in spectrum of industrial applications of yttrium （Y） and the fact that it is widely present in the soils and plants, some of which are agronomically important crops, its effects on plant growth and metabolism are still obscure. Therefore, the aim of this work was to examine the effect of different concentrations of Y on its accumulation and distribution, photosynthetic responses, water relations, free proline concentration and growth of young maize plants. The experiment was done with maize （Zea mays L., hybrid NS-640）, in water cultures, under semi-controlled conditions of a greenhouse. Plants were supplied with half-strength complete Hoagland nutrient solution, to which was added either 0 （control）, 10-5, 10-4 or 10-3 mol/L Y, in the form of Y（NO）3·5H2O. Each variant was set in thirteen replications, with six plants in each replication. Plants were grown for 21 d and they were at the stage of 3 and 4 leaves when they were analyzed. The presence of Y reduced maize growth and photosynthetic performance. Dimensions of stomata significantly decreased while their density significantly increased on both adaxial and abaxial epidermis. Plant height, root length, total leaf area and dry mass also declined. Concentration of photosynthetic pigments （chl a and b and carotenoids） and free proline decreased. Photosynthesis and transpiration were impaired in the presence of Y-their intensities were also reduced, and the same stands for stomatal conductance of water vapor, photosynthetic water use efficiency （WUE） and water content. Although the highest concentration of Y was found in maize roots in each treatment, Y concentration in the second leaf and shoot also significantly increased with an increase in Y concentration in the nutrient solution. Albeit Y concentration was much higher in roots than in shoots, shoot metabolism and growth were much more disrupted. The results demonstrated that young maize plants accumulated significant amount of Y and that th

关键词： yttrium maize photosynthesis water use efficiency rare earths

Factorizations of Fitting classes

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Frontiers of Mathematics in China 2012年第5期7卷 943-954页

作者： Nanying YANG Wenbin GUO N.T. VOROB'ev School of Mathematics University of Science and Technology of China Hefei 230026 China Department of Mathematics Vitebsk State University Vitebsk 210038 Belarus

In this paper, we prove that there exists a infinite set of non-trivial local Fitting classes every element in which is decomposable as a non-trivial product of Fitting classes such that every factor in the product is neither local nor a formation. In particular, this gives a positive answer to Problem 11.25 a） in The Kourovka Notebook.

关键词： Fitting class Normal Fitting class semilocal Fitting class Lockett class

Reduction of peak ground velocity by nonlinear soil response–Ⅱ:excitation by a P-wave pulse

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Earthquake Engineering and Engineering Vibration 2021年第4期20卷 823-841页

作者： Vlado Gičev Mihailo D.Trifunac Maria I.Todorovska Dept.of Computer Science Univ.Goce DelčevTošo Arsov 142000ŠtipR.Macedonia Dept.of Civil Eng. Univ.Southern CaliforniaLos AngelesCalifornia 90089-2531USA Department of Civil Engineering Tianjin UniversityTianjin 300350China

We study the reduction of peak velocity on the ground surface of a soil valley caused by loss of wave energy by large nonlinear strains and strain localization inside the valley,for excitation by a half-sine P-wave *** study is a follow up to our previous study of out of plane response for excitation by an *** this paper,we consider the in-plane response,and assume that the soil material does not support tension,but the normal stress at a point in the soil can be compression(negative)or zero.A point in the soil with zero stress behaves as a stress-free point,it does not transmit normal stress and appears as a crack *** of this,along with the nonlinear response associated with compression and shear,the in-plane response in this study is more complex than that of the out-of-plane SH *** study the interplay of two opposing effects:(i)jump in impedance from a higher value(half-space)to a lower value(valley),which amplifies the linear motions at the free surface of the valley,and(ii)the occurrence of nonlinear zones in the valley,which reduce the motion at the valley surface.

关键词： nonlinear soil response non-linear seismic P waves energy dissipation by yielding soil strain localization

On Finite Non-Solvable Groups Whose Gruenberg-Kegel Graphs are Isomorphic to the Paw

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Communications in Mathematics and Statistics 2022年第4期10卷 653-667页

作者： A.S.Kondrat’ev N.A.Minigulov N.N.Krasovskii Institute of Mathematics and Mechanics of the Ural Branch of the Russian Academy of Sciences 16 S.Kovalevskaya StrYekaterinburg 620108Russia

The Gruenberg-Kegel graph(or the prime graph)Γ(G)of a finite group G is a graph,in which the vertex set is the set of all prime divisors of the order of G and two different vertices p and q are adjacent if and only if there exists an element of order pq in *** paw is a graph on four vertices whose degrees are 1,2,2,*** consider the problem of describing finite groups whose Gruenberg-Kegel graphs are isomorphic as abstract graphs to the *** example,the Gruenberg-Kegel graph of the alternating group A_(10)of degree 10 is isomorphic as abstract graph to the *** this paper,we describe finite non-solvable groups G whose Gruenberg-Kegel graphs are isomorphic as abstract graphs to the paw in the case when G has no elements of order 6 or the vertex of degree 1 ofΓ(G)divides the order of the solvable radical of G.

关键词： Finite group Non-solvable group Gruenberg-Kegel graph The paw

On the Cover-Avoid Property of Injectors for Hartley Classes

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Algebra Colloquium 2015年第2期22卷 211-214页

作者： Yufeng Liu Xiaolan Yi N.T. Vorob'ev School of Mathematics and Informational ScienceShandong Institute of Business and Technology Yantai Shandong 264005 China Department of Mathematics Zhejiang Sci-Tech University Hangzhou Zhejiang 310018 China Department of Mathematics Masherov Vitebsk State University Vitebsk 210038 Belarus

In this paper, we study the cover-avoid property of -injectors on chief factors of a group G for a Fitting class in some universe with partial solubility.

关键词： Fitting class Hartley class -injector cover-avoid property chief factor

Pulse generation with ultra-superluminal pulse propagation in semiconductor heterostructures by superradiant-phase transition enhanced by transient coherent population gratings

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Light(Science & Applications) 2016年第1期5卷 737-743页

作者： Peter P Vasil’ev Richard V Penty Ian H White Centre for Photonic Systems Department of EngineeringUniversity of CambridgeCambridge CB30FAUK Quantum Electronics Division PN Lebedev Physical InstituteMoscow 119991Russia

This paper reports the observation of ultra-superluminal pulse propagation in multiple-contact semiconductor heterostructures in a superradiant emission regime,and shows definitively that it is a different class of emission from conventional spontaneous or stimulated *** population gratings induced in the semiconductor medium under strong electrical pumping have been shown to cause a major decrease of the group refractive index,in the range of 5–40%.This decrease is much greater than that caused by conventional carrier depletion or chirp *** decrease in refractive index in turn causes faster-than-c propagation of femtosecond *** measurement also proves the existence of coherent amplification of electromagnetic pulses in semiconductors at room temperature,the coherence being strongly enhanced by interactions of the light with coherent transient gratings locked to carrier *** pulse-generation technique is anticipated to have great potential in applications where highly coherent femtosecond optical pulses must be generated on demand.

关键词： phase transition population grating superradiance superluminal propagation