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141.
142.
Stimulated Raman scattering is used to prepare ensembles of aligned acetylene molecules in thev 2=1 excited vibrational level. Decay and transfer of the alignment is followed by laser induced fluorescence. Measurements of the initially excited alignment agree well with theoretical calculations. The rate constants for decay decrease as the rotational quantum numberJ of the excited level increases.  相似文献   
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Doklady Earth Sciences - Waters at seventeen mud volcanoes of the Kerch–Taman province in the Northwestern Cis-Caucasus region have been analyzed for Sr isotope composition. The 87Sr/86Sr...  相似文献   
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A series of high structural state plagioclases (Ab-An) was crystallized from glasses. By exchanging Na for K in KCl melts, metastable K-plagioclases (Or-An) were prepared which possess the same structural state as the starting plagioclases. Both series were investigated at 980 K by lead borate solution calorimetry. Continuing the ideas of Carpenter and McConnell (1984) and Carpenter (1992a), the results can be interpreted as follows. In the high plagioclase series, the enthalpies of solution, jHsol, reflect the schemes of Al,Si ordering: (1) analbite-like (C2/m) ordering in the An-poor region 0hXAnА.2, (2) high albite-like (C1¥) ordering in intermediate plagioclases, and (3) anorthite-like (I1¥) ordering in the An-rich region 0.7AnБ. In regions 1 and 2, jHsol decreases as a function of XAn, but increases in region 3 as a consequence of the C1¥MI1¥ ordering reaction. Therefore, it is not a mixing effect but a compositionally restricted ordering effect which causes the excess enthalpies, jHex, to be positive in the plagioclase binary as a whole. Neglecting the existence of phase transitions at XAn=0.2 and XAn=0.7, jHex can be approximated by a two-parameter Margules model yielding WHAnAb=14Dž kJ/mol and WHAbAn=40Dž kJ/mol. jHsol values of I1¥ plagioclases (XAn>0.7) can be "corrected" for the C1¥MI1¥ ordering effect (Carpenter 1992a). When combining the corrected values with the jHsol data which were actually measured on the C1¥ plagioclases (XAn<0.7), negative excess enthalpies are generated in the plagioclase binary. This may be expected when C1¥ ordering occurs relative to topochemically monoclinic reference states of analbite and hypothetical anorthite devoid of I1¥ order. The solution experiments on the K-plagioclases resulted in similar characteristics as those found for the plagioclases. However, in addition to the ordering effects observed in the plagioclase binary, volume mismatch effects contribute to jHex in the K-plagioclase series. jHex can be represented by a Margules model with WHAnOr=60ᆞ kJ/mol and WHOrAn=91ᆢ kJ/mol when the phase transitions at XAn=0.2 and XAn=0.7 are again neglected. The contribution of the volume mismatch effect to jHex is considerable, as appears from the large difference between the K-plagioclase and the plagioclase Margules parameters. Their difference corresponds to a practically symmetrical dependence of jHexvolmism on composition, with WHvolmism=48ᆡ kJ/mol.  相似文献   
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Data layers that represent geographical constraints in a multidimensional GIS model must be appropriately weighted to effectively account for the diversity as well as the functional and spatial interrelationships between the constraints. This paper presents a spatial analysis weighting algorithm (SAWA) using Voronoi diagrams. The basic functions of the SAWA are defined so that the spatialization of weights is done according to two approaches: a global spatialization method based on the statistical distribution of the original data and a contextual approach where neighbourhood defined by Voronoi diagrams is integrated into the weighting functions. Different simulations on artificial and real maps applied to the problem of shortest path optimisation are analysed. The results show that the effective integration of the spatial dimension in a weighting process is not only possible but also improves the optimisation of shortest paths. Research is continuing to improve the contextual phase of the algorithm.  相似文献   
149.
We discuss the multi-Gaussian decomposition of the [O III] λλ 4959,5007 emission line profiles from 2-D spectroscopy. We found that a model based on five main gaseous components can reproduce the observed line profiles consistently. The morphology of the intensity maps of some of these gaseous subsystems seems bipolar. This is in better agreement with current ideas about the alignment of the ionization in AGNs than the relatively amorphous morphology seen in filter images. The centre of the inter-pole region is sited ~ 2″ NE of the optical nucleus, close to the origin of the strong outflow of ionized gas recently reported (Arribas et al. 1996). This suggests that the putative hidden nucleus of NGC 1068 could be sited near to this point.  相似文献   
150.
Five different refraction formulas were applied to SiO2 polymorphs in order to determine the most suitable refractive index-density relation. 13 SiO2 polymorphs with topological different tetrahedral frameworks are used in this study including eight new low density SiO2 polymorphs — so called “guest free porosils”. These SiO2 polymorphs cover a density range from 1.76 to 2.92 g/cm3. The mean refractive indices (ovn) of the porosils have been determined by the immersion method, the densities (ρ) were calculated from the unit cell parameters. Assuming the polarizability (α) of all SiO2 polymorphs to be constant the general refractivity formula $$\{ 2\overline {11} 0\} \langle 0001\rangle $$ turned out to be the most suitable for SiO2 polymorphs. Regression analysis yields an electronic overlap parameter b=1.2(1).  相似文献   
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