Stark definition

Owen s detailed descriptions of homology and analogy, as opposed to the stark definitions of homologue and analogue, appeared in his Archetype and Homologies of the Vertebrate... 

He suggested that the ionic formulas, like the nonionic formulas, "represent formulations of extremes" and that no bond across the ring is required. Using the hypothesis of the motions of valence electrons, as developed by Stark and Kossel, Arndt suggested the possibility of intermediate valence states (Zwitterstufen) as well.32 Independently, Robinson proposed possible electronic shifts in pyrones and similar systems, but he did not state the idea of a definite "intermediate state" of the molecule between the ionic and uncharged formulas.33... 

Saponins appear to lower plasma LDL cholesterol concentration by interfering with cholesterol absorption. Studies in rats and monkeys fed naturally occurring saponins exhibited significant reductions in cholesterol absorption efficiency and an increase in fecal cholesterol excretion (Malinow et al., 1981 Nakamura et al., 1999 Sidhu et al., 1987). Decreased bile acid absorption and increased excretion has also been reported in animals fed saponins (Malinow et al., 1981 Nakamura et al., 1999 Stark and Madar, 1993). One possible mechanism of action for decreased cholesterol absorption is the ability of saponins to form insoluble complexes with cholesterol (Gestetner et al., 1972 Malinow et al., 1977). In an effort to isolate the specific properties of saponins, Malinow (1985) prepared a variety of synthetic saponins in which the complex carbohydrate moieties of native plant saponins were replaced with simplified carbohydrates such as glucose or cellobiose. One of these synthetic saponins, tiqueside (Pfizer, Inc.), can effectively precipitate cholesterol from micelle solutions in vitro and inhibit cholesterol absorption in a variety of animals (Harwood et al., 1993) and in humans (Harris et al., 1997). But despite ample data showing the formation of a saponin/cholesterol complex in vitro, there is essentially no definitive evidence that complexation occurs in the intestinal lumen (Morehouse et al., 1999). 

Recently, we also observed an anomalous thermalization phenomenon in Er Gd203 (1 at%) nanocrystals with diameters of 40-50 nm. In the excitation spectra at 2.9 K, hot bands originating from the upper stark level of 4Ii5/2 (38 cm-1) were observed. These hot bands disappear when temperature goes up to 5 K. Our preliminary results show that the anomalous thermalization phenomena in this system are more complicated, because they depend on the laser power and temperature. The effect of laser heating or temperature fluctuation in nanocrystals must be ruled out before a definite conclusion can be reached. 

Finally, it is necessary to discuss whether it is possible to implement experimentally a noticeable (in comparison with Tp) value of the Stark shift los- From the definition of Tp (5.24) and oos (5.25),we have... 

These two functions do not have definite parities but the symmetric and antisymmetric combinations of them do we use these combinations to calculate both the Stark effect and the electric dipole transition probabilities. 

An inevitable consequence of de Broglie s standing-wave description of an electron in an orbit around the nucleus is that the position and momentum of a particle cannot both be known precisely and simultaneously. The momentum of the circular standing wave shown in Figure 4.18 is given exactly hj p = h/, but because the wave is spread uniformly around the circle, we cannot specify the angular position of the electron on the circle at all. We say the angular position is indeterminate because it has no definite value. This conclusion is in stark contrast with the principles of classical physics in which the positions and momenta are all known precisely and the trajectories of particles are well defined. How was this paradox resolved ... 

This result is in stark contrast to a study of Moyna et alf who applied nearly the same formalism for calculating the proton chemical shifts [Eq. (40)]. For the tripeptide under investigation only a limited set of intra-residue proton distances was available. The definition of structure was therefore greatly improved when the proton chemical shift constraints were switched on. The chemical shift refinement reduced the rmsd for the backbone atoms from 1.2 A to 0.2 A, and it revealed a single set of conformers with both peptide bonds in trans conformation. The shift constraints drove the molecule energetically uphill by 3.9 kcal/mol but produced a well-defined minimum within the energy hyper-surface. Obviously, chemical shift constraints will produce well-defined structures when other constraints are not available from experiment. 

Further, combinatorial synthesis by definition results in multiple end products, "libraries" as it were of chemical compounds, in stark contrast to the usual goal of a single, pure, final product. We will discuss the implications of combinatorial chemistry in synthesis in some depth in the section entitled Similarity and Categorization. 

The AC Stark effect is relevant, not only in atomic spectroscopy, but also in solid state physics. The biexciton state (or excitonic molecule), where two Wannier excitons are bound by the exchange interaction between electrons, occurs in various semiconductors (see section 2.22). Various experiments on the AC Stark effect of excitons have been reported, but the clearest example to date is probably the observation of the Rabi splitting of the biexciton line in CuC reported by Shimano and Kuwata-Gonokami [477]. It is very interesting to consider how Bloch states in solids, which themselves are delocalised and periodic, are dressed or modified by the electromagnetic field, since their properties are rather different from those of purely atomic states, which are by definition completely localised. 

Stark, K.L. McMahon, J.A. McMahon, A.P. FGFR-4, a new member of the fibroblast growth factor receptor family, expressed in the definitive endo-derm and skeletal muscle lineages of the mouse. Development, 113, 641-651 (1991)... 

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