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21.
The classification of finite simple strongly real groups is complete. It is easy to see that strong reality for every nonabelian
finite simple group is equivalent to the fact that each element can be written as a product of two involutions. We thus obtain
a solution to Problem 14.82 of the Kourovka Notebook from the classification of finite simple strongly real groups. 相似文献
22.
Pulse compression by use of deformable mirrors 总被引:7,自引:0,他引:7
Zeek E Maginnis K Backus S Russek U Murnane M Mourou G Kapteyn H Vdovin G 《Optics letters》1999,24(7):493-495
An electrostatically deformable, gold-coated, silicon nitride membrane mirror was used as a phase modulator to compress pulses from 92 to 15 fs. Both an iterative genetic algorithm and single-step dispersion compensation based on frequency-resolved optical gating calibration of the mirror were used to compress pulses to within 10% of the transform limit. Frequency-resolved optical gating was used to characterize the pulses and to test the range of the deformable-mirror-based compressor. 相似文献
23.
24.
A. D. Vdovin Kh. A. Kadyrov M. R. Yagudaev Kh. B. Allayarov A. K. Nistryan 《Chemistry of Natural Compounds》1982,17(3):279-280
The structure of the alkaloid trisphaeridine has been established with the aid of IR and UV spectroscopy, high-resolution mass spectroscopy, and PMR and13C NMR spectroscopy.Institute of the Chemistry of Plant Substances, Academy of Sciences of the Uzbek SSR, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 356–358, May–June, 1981. 相似文献
25.
26.
An adaptive optical system with a subjective feedback loop is used to improve the visual acuity and to determine the aberrations of the human eye. Corrections of as many as 12 low-order aberration modes were made, based on the perceived sharpness of the test object observed through the adaptive optical system. The acuity of vision was improved by adjustment of the weights of the orthogonal modes produced by a deformable mirror. Objective measurements of the correcting aspherical figures, obtained in independent subjective correction cycles for one person, demonstrated good repeatability. Participants in the study with strong ocular aberrations reported moderate to significant improvement of their visual acuity, estimated with the U.S. Air Force 1951 acuity chart. 相似文献
27.
Selective chemical etching and transmission electron microscopy are used to study the defect formation in Ge1?xSix/Ge(111) epitaxial heterostructures at 0.01<x<0.35. As the Si content in the solid solution (SS) increases, the dislocation densities in the epitaxial layer, at the interface, and in the near-interface region in the substrate are found to vary nonmonotonically. The difference in the depth distribution of dislocations observed in the heterostructures in three different SS composition ranges is caused by the effect of the SS composition on the kinetics of misfit-stress relaxation, in particular, on the intensity of misfit-dislocation generation and multiplication. It is found that, in the heterostructures grown by hydride epitaxy at 600°C, misfit-dislocation multiplication through a modified Frank-Read mechanism occurs only in the range 0.03<x<0.20. The results obtained are explained in the context of the effect of silicon-rich microprecipitates, which form during the spinodal decomposition of the SS, on dislocation generation and motion in the epitaxial layer. A mechanism is proposed for misfit-dislocation generation by heterogeneous sources in the epitaxial layer; the mechanism is based on the generation of interstitial dislocation loops near microprecipitates. 相似文献
28.
We demonstrate the use of a deformable-mirror pulse shaper, combined with an evolutionary optimization algorithm, to correct high-order residual phase aberrations in a 1-mJ, 1-kHz, 15-fs laser amplifier. Frequency-resolved optical gating measurements reveal that the output pulse duration of 15.2 fs is within our measurement error of the theoretical transform limit. This technique significantly reduces the pulse duration and the temporal prepulse energy of the pulse while increasing the peak intensity by 26%. It is demonstrated, for what is believed to be the first time, that the problem of pedestals in laser amplifiers can be addressed by spectral-domain correction. 相似文献
29.
Yu. N. Khanin E. E. Vdovin L. Eaves M. Henini 《Bulletin of the Russian Academy of Sciences: Physics》2007,71(8):1120-1123
A high narrow peak of interlayer differential tunnel conductivity is observed at low temperatures in heterostructures with two closely located electronic layers in the absence of magnetic field. The analysis of experimental results suggests that this peak is due to the interlayer phase coherence that arises in the system as a result of the Bose condensation of interlayer excitons (electron-hole pairs) belonging to different layers, in accordance with the recent theoretical predictions. 相似文献
30.