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121.
A subgroup H of a finite group G is said to be ??-semipermutable in G if it permutes with all the Sylow subgroups Q of G such that (|H|, |Q|) = 1 and (|H|, |Q G |) ?? 1. A rather remarkable result of Lukyanenko and Skiba (Rend Semin Mat Univ Padova, 124:231?C246, 2010) is: a finite solvable group G is a PST-group if and only if every subgroup of Fit(G) is ??-semipermutable. A local version of this result is established in this paper. A subgroup H of G is said to be ??-seminormal provided that it is normalized by all Sylow subgroups Q such that (|H|, |Q|) =?1 and (|H|, |Q G |) ???1. It is shown that a finite solvable group is a PST-group if and only if every subgroup of Fit(G) is ??-seminormal in G. 相似文献
122.
The photoluminescence spectrum of Hg0.3Cd0.7Te at 77K consists of a narrow, high energy free exciton line D and a broad, low energy deep level E. As a function of incident excitation power, the E line must be saturated before the D line can be observed. We have constructed a simple model that agrees well with the experimental dependences of the luminescence intensities of the D and E lines on excitation power. 相似文献
123.
J. F. Donegan J. P. Doran R. P. Stanley J. Hegarty
R. D. Feldman
R. F. Austin 《Applied Surface Science》1991,50(1-4):321-324The technique of resonant Rayleigh scattering is used to determine the homogeneous linewidth across the inhomogeneously broadened exciton resonance in a Cd0.25Zn0.75Te/ZnTe multiple quantum well structure. An order of magnitude increase of the Rayleigh scattering signal over background is observed on tuning a narrow-band laser through the exciton resonance at low temperatures. Spectral and temporal measurements show the effect to be a true scattering process rather than luminescence. The interface and alloy fluctuations in the quantum well give rise to spatial fluctuations in the dielectric response of the system while the large exciton resonance causes strong enhancement of scattering. The homogeneous linewidth was calculated across the exciton resonance. The technique is compared with the dephasing and hole-burning techniques more commonly used in homogeneous linewidth measurements. 相似文献
124.
Among the Carleman operators on Banach lattices, we consider the operators that are decomposition operators or lattice homormphisms. Using a generalization of an atom, characterizations for these two classes of operators on Banach lattices with order units are provided. 相似文献
125.
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127.
Nanostructures, with their very large surface to volume ratio and their non-planar geometry, present an important challenge to surface scientists. New issues arise as to surface characterization, quantification and interface formation. This review summarizes the current state of the art in the synthesis, composition, surface and interface control of CdSe nanocrystal systems, one of the most studied and useful nanostructures. 相似文献
128.
J. Feldman R. Froese N. Ghoussoub C. Gui 《Calculus of Variations and Partial Differential Equations》1998,6(2):95-104
We show that for some , , the following inequality holds: for every function on satisfying and . This improves a result of Chang and Yang [C-Y2] in the axially symmetric case.
Received October 17, 1996 / Accepted November 11, 1996 相似文献
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Gomez-Cadenas JJ Heusch CA Abrams G Adolphsen CE Akerlof C Alexander JP Alvarez M Amidei D Baden AR Ballam J Barish BC Barklow T Barnett BA Bartelt J Blockus D Bonvicini G Boyarski A Boyer J Brabson B Breakstone A Brom JM Bulos F Burchat PR Burke DL Butler F Calvino F Cence RJ Chapman J Cords D Coupal DP DeStaebler HC Dorfan DE Dorfan JM Drell PS Feldman GJ Fernandez E Field RC Ford WT Fordham C Frey R Fujino D Gan KK Gidal G Gladney L Glanzman T Gold MS Goldhaber G Golding L Green A 《Physical review letters》1991,67(8):1007-1010