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1.
Let 1→N→G→G/N→1 be a short exact sequence of profinite groups, and let p be a prime number. We prove that if G is of finite cohomological p-dimension n:=cdp(G)<∞ and if the order of is finite for k:=cdp(N), the virtual cohomological p-dimension of G/N equals n?k. To cite this article: T. Weigel, P. Zalesskii, C. R. Acad. Sci. Paris, Ser. I 338 (2004). 相似文献
2.
S. D. Moshchitskii G. A. Zalesskii A. F. Pavlenko 《Chemistry of Heterocyclic Compounds》1974,10(1):84-87
Depending on the conditions, the reaction of pentachloropyridine N-oxide with potassium hydrogen sulfide leads to the N-oxide of the potassium salt of 3,4,5,6-tetrachloropyridin-2-thiol or the dipotassium salt of 3,4,5-trichloropyridine-2,6-dithiol, which are converted by the action of dimethyl sulfate into the corresponding methylthio derivatives. Oxidation of the latter has given sulfones. It has been shown that for these sulfones,reactions with nucleophilic reagents take place at the methylsulfonyl group and not at the chlorine atoms. 相似文献
3.
We determine the Zariski-dense subgroups of Chevalley groups and their twisted analogues over infinite algebraic extensions
of finite fields. It turns out that these are essentially forms of the same group (possibly becoming twisted) over smaller
infinite fields. It follows from our classification that if
is a simple algebraic group over the algebraic closure of a finite field, then a dense subgroup of
can never be maximal, and so the maximal subgroups of
are necessarily closed. It follows that Seitz’s determination of the closed maximal subgroups of
actually gives all the maximal subgroups.
It also enables us to prove that ifG is a simple Chevalley group or twisted type over an infinite algebraic extension of a finite field, then in every non-trivial
permutation representation ofG, every finite subgroup has a regular orbit. It follows that every non-trivial permutation module forG over a fieldk iskG-faithful. This is relevant to a programme of studying ideals in group rings of simple locally finite groups.
To John Thompson in recognition of his many outstanding contributions to group theory 相似文献
4.
Let be a division ring and let be a finite-dimensional -vector space, viewed multiplicatively. If is the multiplicative group of , then acts on and hence on any group algebra . Our goal is to completely describe the semiprime -stable ideals of . As it turns out, this result follows fairly easily from the corresponding results for the field of rational numbers (due to Brookes and Evans) and for infinite locally-finite fields. Part I of this work is concerned with the latter situation, while Part II deals with arbitrary division rings.
5.
A. V. Zalesskii A. A. Frolov T. A. Khimich A. A. Bush 《Physics of the Solid State》2003,45(1):141-145
By analyzing the NMR line shape, the transformation of a spatially spin-modulated magnetic structure in BiFeO3 into an ordinary spatially uniform structure of the LaFeO3 orthoferrite in Bi1?xLaxFeO3 solid solutions is studied. The measurements are made using a spin-echo technique at temperatures of 77 and 4.2 K on ceramics with compositions x=0, 0.1, 0.2, 0.61, 0.9, and 1.0 enriched by the 57Fe isotope. It is shown that the spin-modulated structure disappears near the concentration x=0.2, which corresponds, according to the published data, to the phase transition with a change in the unit-cell symmetry R3c → C222. A formula is obtained describing the NMR absorption line shape for the spin-modulated structure with account of local line-width. Theoretical spectra adequately describe the evolution of the experimental spectrum in the concentration range 0≤x≤0.2. Highly nonuniform local magnetic fields in the intermediate compositions make it impossible to detect NMR signals in a sample with x=0.61. A uniform magnetic structure characterized by a single narrow line arises in the range of existence of a phase with the symmetry Pnma typical of the pure orthoferrite LaFeO3. 相似文献
6.
P. A. Zalesskii 《Siberian Mathematical Journal》1989,30(2):227-235
Minsk. Translated from Sibirskii Matematicheskii Zhurnal, Vol. 30, No. 2, pp. 73–84, March–April, 1989. 相似文献
7.
Studies of magnetization, magnetoresistance, and magnetic oscillations in semiconductor-multiferroics Eu(1-x)Ce(x)Mn2O5 (x = 0.2-0.25) (ECMO) at temperatures ranging from 5 to 350 K in magnetic fields up to 6 T are presented. It is shown that phase separation and charge carrier self-organization in the crystals give rise to a layered superstructure perpendicular to the c axis. An effect of magnetic field cycling on the superstructure, magnetization, and magnetoresistance is demonstrated. X-ray diffraction studies of ECMO demonstrating the effect of magnetic field on the superstructure are presented. The de Haas-van Alphen magnetization oscillations in high magnetic fields and the temperature-induced magnetic oscillations in a fixed magnetic field are observed at low temperatures. Below 10 K the quantum corrections to magnetization due to the weak charge carrier localization in 2D superlattice layers occur. It is shown that at all the temperatures the Eu(1-x)Ce(x)Mn2O5 magnetic state is dictated by superparamagnetism of isolated ferromagnetic domains. 相似文献
8.
9.
10.
L. E. Svistov V. A. Chubarenko A. Ya. Shapiro A. V. Zalesskii G. A. Petrakovskii 《Journal of Experimental and Theoretical Physics》1998,86(6):1228-1233
Magnetic resonance of the low-frequency spin-wave branch in the Bi2CuO4 antiferromagnet with an easy-plane anisotropy has been studied. Angular, frequency, and temperature dependences of the position
and width of the antiferromagnetic resonance (AFMR) line have been measured. Our measurements combined with earlier data [H.
Ochta, K. Yoshida, T. Matsuya, T. Nanba, M. Motokawa, K. Yamada, Y. Endon, and S. Hosoya, J. Phys. Soc. Jpn. 61, 2921 (1992); E. W. Ong, G. H. Kwei, R. A. Robinson, B. L. Ramakrishna, and R. B. von Dreele, Phys. Rev. B 42, 4255 (1990) [ have allowed us to determine anisotropy constants of this material and to account for the unusual character
of its static susceptibility anisotropy. The AFMR line shifts to the high-field side and broadens in a temperature range of
10–15 K, and the cause of this has remained unclear. In the low-temperature range the line shows a hysteresis corresponding
to a static field magnitude several times as large as the spin-flop field. The position and width of the AFMR line depend
sensitively on the sample preparation technique.
Zh. éksp. Teor. Fiz. 113, 2244–2255 (June 1998) 相似文献