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991.
Tse JS Shaw DM Klug DD Patchkovskii S Vankó G Monaco G Krisch M 《Physical review letters》2008,100(9):095502
Oxygen K-edge x-ray absorption spectra of high-density amorphous (HDA) ice, low-density amorphous ice Ic, ice Ih, normal and deuterated liquid water were measured with the synchrotron x-ray Raman scattering method under almost identical experimental conditions by in situ heating of an HDA ice sample. The distinct preedge structure previously reported in water was observed in all the spectra. The results show that core-hole excitations are localized and not strongly affected by the local environment. Therefore, the existence of the preedge feature is not a concise indicator of the magnitude of local disorder within the hydrogen bonded network. The intensity of the near-edge absorption shifts into the postedge region when the hydrogen bond network becomes more ordered. This observation is interpreted as an enhancement of Wannier over Frenkel excitations in an ordered crystal. 相似文献
992.
Effects of core polarization and tensor coupling on the magnetic moments in 13ΛC, 17Λ, and 41ΛCa Λ-hypernuclei are studied by employing the Dirac equation with scalar, vector and tensor potentials. It is found that the effect of core polarization on the magnetic moments is suppressed by Λ tensor coupling. The Λ tensor potential reduces the spin--orbit splitting of pΛ states considerably. However, almost the same magnetic moments are obtained using the hyperon wavefunction obtained via the Dirac equation either with or without the Λ tensor potential in the electromagnetic current vertex. The deviations of magnetic moments for pΛ states from the Schmidt values are found to increase with nuclear mass number. 相似文献
993.
Eric Maurice Gerard Monnom Greg W. Baxter Scott A. Wade Bill P. Petreski Stephen F. Collins 《Optical Review》1997,4(1):A89-A91
A fluorescence intensity ratio technique has been applied to Pr3+: ZBLAN glass, realising a point temperature sensor. We present data for a blue light emitting diode-pumped prototype which provides accurate and self-referenced measurements. 相似文献
994.
Email discussion groups provide a useful way of organizing email communities with a common interest in a certain topic. Emails submitted to the discussion group are sent automatically to each individual member, thereby eliminating the need to send multiple emails. This method may present unexpected difficulties however, when it comes to cooperation between members. An experimental study shows that email requests for help sent through discussion groups received less responses than emails sent individually to members of a group. Furthermore, subscribers to large discussion groups responded less often to help requests, whether they were sent to the group as a whole or to individuals. These results are discussed in terms of the separate roles of social cues and experience on the diffusion of responsibility effect. 相似文献
995.
We give a brief indication of how elliptic, parabolic and hyperbolic partial differential equations with memory arise when modelling viscoelastic materials. We then point out the urgent need for adaptive solvers for these problems and, employing the methodology of Eriksson, Johnson et al. (e.g., SIAM J. Numer. Anal. 28 (1991)), we given ana posteriori error estimate for a model two-point hereditary boundary value problem. The strengths and weaknesses of the analysis and estimate are discussed.Dedicated to Professor J. Crank on the occasion of his 80th birthday 相似文献
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