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51.
W.N Hsieh 《Journal of Combinatorial Theory, Series A》1975,18(3):252-261
The following theorem is proved. It is a generalization of the problem for finite vector spaces analogous to a theorem of Kleitman for finite sets.Let V be an n-dimensional vector space over a finite field F of q elements. Suppose we have two collections, one consisting of k- and the other of m-dimensional subspaces of V with the property that the intersection of each member of one with each member of the other has dimension no less than r.Then if n ? k + m + 2 or n ? k + m + 1 and q ? 3, there are either no more than members in the first family or fewer than members in the second.The method used leads to a similar result for sets, provided that n ? r + (r + 1)(k ? r)(m ? r + 1) with k ? m. 相似文献
52.
Interferometry is introduced for the first time to the study of Kerr magneto-optic effects. A polarized interferometer is used in direct measurement of the phase relationship between the two Kerr components from the head-on domains in a magnetic thin film. 相似文献
53.
54.
Tamm-Dancoff calculations including the complete 1p and 2s-1d shells are presented for non-normal parity states of nuclei with mass 15, 16 and 17. The basis is confined to ?ω excitations. Spurious states have been eliminated. The particle-particle and hole-hole interactions were taken from previous work. The particle-hole interaction was represented by 80 matrix elements from Kuo, eight of which were varied to fit 30 selected levels with a rms deviation of 310 keV. Spectroscopic factors and electromagnetic transition rates generally agree quite well with the experimental data. It is shown that the inclusion of the 1p and 1d. shells is essential even at low excitation energies in these nuclei. 相似文献
55.
Haverkort MW Hu Z Tanaka A Ghiringhelli G Roth H Cwik M Lorenz T Schüssler-Langeheine C Streltsov SV Mylnikova AS Anisimov VI de Nadai C Brookes NB Hsieh HH Lin HJ Chen CT Mizokawa T Taguchi Y Tokura Y Khomskii DI Tjeng LH 《Physical review letters》2005,94(5):056401
Utilizing a sum rule in a spin-resolved photoelectron spectroscopic experiment with circularly polarized light, we show that the orbital moment in LaTiO3 is strongly reduced from its ionic value, both below and above the Ne el temperature. Using Ti L2,3 x-ray absorption spectroscopy as a local probe, we found that the crystal-field splitting in the t2g subshell is about 0.12-0.30 eV. This large splitting does not facilitate the formation of an orbital liquid. 相似文献
56.
We present experimental demonstrations of spectral diversity filters with spherical beam volume holograms for multimodal multiplex spectroscopy. Major properties of filters under diffuse-light illumination are discussed. The comparisons of spectral diversity between the transmission geometry holograms and the reflection geometry holograms are also studied. The results show that there is a trade-off between the degree of the spatial coherence of the source and the spectral diversity of the filter. We also conclude that the reflection geometry holograms have better spectral diversity and less sensitivity to the spatial coherence of the source. 相似文献
57.
Femtosecond pump pulses are strongly attenuated in lithium niobate owing to two-photon absorption; the relevant nonlinear coefficient beta(p) ranges from approximately 3.5 cm/GW for lambda(p) = 388 nm to approximately 0.1 cm/GW for 514 nm. In collinear pump-probe experiments the probe transmission at the double pump wavelength 2lambda(p) = 776 nm is controlled by two different processes: A direct absorption process involving pump and probe photons (beta (r) = 0.9 cm/GW) leads to a pronounced short-duration transmission dip, whereas the probe absorption by pump-excited charge carriers results in a long-duration plateau. Coherent pump-probe interactions are of no importance. Hot-carrier relaxation occurs on the time scale of < or approximately equal to 0.1 ps. 相似文献
58.
Hsieh HT Psaltis D Beyer O Maxein D von Korff Schmising C Buse K Sturman B 《Optics letters》2005,30(17):2233-2235
Spatial gratings are recorded holographically by two femtosecond pump pulses at 388 nm in lithium niobate (LiNbO3) crystals and read out by a Bragg-matched, temporally delayed probe pulse at 776 nm. We claim, to our knowledge, the first holographic pump-probe experiments with subpicosecond temporal resolution for LiNbO3. An instantaneous grating that is due mostly to the Kerr effect as well as a long-lasting grating that results mainly from the absorption caused by photoexcited carriers was observed. The Kerr coefficient of LiNbO3 for our experimental conditions, i.e., pumped and probed at different wavelengths, was approximately 1.0 x 10(-5) cm2/GW. 相似文献
59.
A simple spectrophotometric method is proposed for determining deacetylation degrees (DD) of chitinous materials using phosphoric acid as the UV-transparent solvent system. Calibrating by the extinction coefficients (A(210)) of D-glucosamine and N-acetyl-D-glucosamine, DD values (24-88%) were computed numerically. The results correlated well (R(2) = 0.9805, n = 50) with those obtained by solid-state (13)C NMR. Comparison of the results obtained by the proposed UV method and solid-state (13)C NMR. 相似文献
60.
Electrophoresis of biological cells: charge-regulation and multivalent counterions association model
The electrophoresis of a biological cell is analyzed theoretically. An entity, which is of amphoteric nature, is used to simulate its electrophoretic behavior. To reflect conditions of practical interest, we assume that the liquid phase contains mixed (a:b)+(c:b) electrolytes, where a and c are the valences of cations, and b is the valence of anions. We consider the case where the surface of a cell contains both bivalent acidic and monovalent basic functional groups, the dissociation/association of them yields fixed surface charge, and the multivalent cations in the liquid phase are allowed to combine with dissociated acidic functional groups, which has the effect of lowering the charge density on cell surface. The electrophoretic behaviors of a cell under various conditions are illustrated. The results obtained can be used to identify the types of functional groups that may be present on cell surface. On the other hand, if the surface functional groups involved in cell electrophoresis are known, then their density and the associated dissociation/association constants can be estimated from experimental data. 相似文献