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Nontrivial observation

It is curious to note, that sulfur-containing epoxy polymers the greatest deformability is reached at the greatest chemical cross-linking density realized at = 1.20 [49] (see Fig. 7.9). This nontrivial observation can be explained within the frameworks of the fractal analysis. As it is known [17],... [Pg.155]

Phase transitions in two-dimensional layers often have very interesting and surprising features. The phase diagram of the multicomponent Widom-Rowhnson model with purely repulsive interactions contains a nontrivial phase where only one of the sublattices is preferentially occupied. Fluids and molecules adsorbed on substrate surfaces often have phase transitions at low temperatures where quantum effects have to be considered. Examples are molecular layers of H2, D2, N2 and CO molecules on graphite substrates. We review the path integral Monte Carlo (PIMC) approach to such phenomena, clarify certain experimentally observed anomalies in H2 and D2 layers, and give predictions for the order of the N2 herringbone transition. Dynamical quantum phenomena in fluids are analyzed via PIMC as well. Comparisons with the results of approximate analytical theories demonstrate the importance of the PIMC approach to phase transitions where quantum effects play a role. [Pg.78]

Amoroso and Patt [amoro72] observed that, as a subset of the set of all possible rules, the set of nontrivial reversible rules appeared to be exceedingly small. [Pg.371]

An important issue concerning reversible CA is their construction. In particular, we are interested in knowing if there is some systematic method by which reversible CA rules can be constructed from scratch. On the one hand - if the desire is to randomly choose a reversible rule out of the set of all possible rules, the outlook for success is very dim. Amoroso and Patt [amoro72], for example, had observed that, within the space of all possible rules, the set of nontrivial reversible rules appeared to be exceedingly small. Sears [sears71] had also shown that the set of invertible CA actually constitutes a vanishingly small subset. On the other hand, if the desire is to simply define some representative samples of reversible rules (or some set of rules that may also possess some additional special features), a number... [Pg.372]

The main problems encountered in the investigation of tantalum- and niobium-containing fluoride and oxyfluoride complexes are related to the tendency of the compounds to undergo hydrolysis, particularly at elevated/high temperatures. In addition, the interpretations of the observed effects are often nontrivial and unclear due to the relatively complicated inter-particular interactions and changes that occur under thermal treatment. From this point of view, vibration spectroscopy methods are of high importance due to the dependence of solid phase spectra on the temperature, which, above all, stems from the nature of such inter-ionic interactions [369]. [Pg.195]

Until very recently, however, the same could not be said for reactive systems, which we define to be systems in which the nuclear wave function satisfies scattering boundary conditions. It was understood that, as in a bound system, the nuclear wave function of a reactive system must encircle the Cl if nontrivial GP effects are to appear in any observables [6]. Mead showed how to predict such effects in the special case that the encirclement is produced by the requirements of particle-exchange symmetry [14]. However, little was known about the effect of the GP when the encirclement is produced by reaction paths that loop around the CL... [Pg.2]

Once one has extracted T e and an explanation of the GP effect on the nuclear dynamics will follow immediately. The dynamics in T e is decoupled from the dynamics in To, and thus any observable will show GP effects only if the corresponding operator samples and To in a region of space where these functions overlap. In a nonencircling nuclear wave function, and never overlap, and this gives us a diagrammatic proof (Fig. 4) of the well-known result that a nonencircling wave functions shows no nontrivial GP effects. [Pg.8]

The probe molecules of greatest historical interest in catalysis are the Hammett indicators [13]. The difficulty of making reliable visual or spectrophotometric observations of the state of protonation of these species on solids is well known. We have recently carried out the first NMR studies of Hanunett indicators on solid acids [ 14]. This was also the occasion of the first detailed collaboration between the authors of this article, and theoretical methods proved to strongly compliment the NMR experiments. The Hanunett story is told after first reviewing the application of theoretical chemistry to such problems. Central to the application of any physical method in chemistry is the process of modeling the relationship between the observables and molecular structure. However often one does this, it is rarely an exact process. One can rationalize almost any trend in isotropic chemical shift as a function of some variation in molecular structure - after the fact, but the quantitative prediction of such trends in advance defies intuition in most nontrivial cases. Even though the NMR spectrum is a function... [Pg.575]

This overview presents some cases in which sequence profile-based methods have been able to predict nontrivial structural and evolutionary relationships between proteins and then discusses the current state of structural genomics as assesed using these methods. This discussion is not a comprehensive review of profile-based methods for sequence analysis and their application in structural genomics rather observations made with PSI-BLAST-constructed PSSMs are emphasized, and results produced by other methods are cited only as needed for discussion. [Pg.248]

The concentration of a solute or adsorbate may be a nontrivial function of the distance to the surface, a function which contains information about the thermodynamics of the surface interaction. To explore the fluorophore concentration C(z) as a function of distance z from the surface, one can record the observed fluorescent intensity F as the characteristic depth d of the evanescent wave is varied. The mathematics of this is discussed immediately following Eqs. (7.44) and (7.45) above. [Pg.323]

Since in this problem not only the limit but also the character of convergence matters we conclude that consistent homogenization of the micromodel should lead to a description in a broader functional space than is currently accepted. One interesting observation is that the concave part of the energy is relevant only in the region with zero measure where the singular, measure valued contribution to the solution is nontrivial (different from point mass). We remark that the situation is similar in fracture mechanics where a problem of closure at the continuum level can be addressed through the analysis of a discrete lattice (e.g. Truskinovsky, 1996). [Pg.186]

This transformation leaves both jRq and 2 = Pen 2 (Eq. (7.10)) invariant. It just expresses naive dimensional analysis in the continuous chain model. The power of the RG-approach lies in the fact that we can construct nontrivial realizations. These take into account more than just the leading n-dependence of each order of perturbation theory and therefore obey the condition of invariance of the macroscopic observables up to much smaller corrections. [Pg.129]

Let us now embed the renormalization group, Constructed in Chap. 8, iftto this general framework. As mentioned above, relation (8.5) shows that the RG we are searching for must be a nonlinear representation of the group of dilatations in the space of parameters. , n,/ e). These are the microscopic parameters of the model, and the representation shall leave macroscopic observables invariant. Furthermore we want the representation to show a nontrivial fixed point. In Sect. 8.2 we have constructed such a representation based on first order perturbation theory. The invariance constraint is obeyed within deviations of order 1+e 2, no = n(A = 1). Equations (8.38), (8.42) give the parameter flow under this nonlinear representation in the standard form (10.28),... [Pg.165]

The final step to achieve (-)-swansonine from the indolizidine 11 required oxidation of the alkene, which proved to be surprisingly nontrivial. A procedure to carry out this transformation using 0s04, NMO, acetone and water at room temperature has been reported to give good selectivity (88 12) in favour of the desired configuration. In the case of the oxidation of 11, after desilylation and triacetate protection almost no diastereoselectivity was observed (12-13 = 50 50-42 58). An alternative method was implemented which required AD-mix-alpha,22 which improved the diastereoselectivity of 12 13 to (20 1). Final hydrolysis of 12 using Amberlite resin yielded the desired product. [Pg.323]

In the case of the recent experiment with hydrogen-like carbon the nontrivial QED effects contribute an observable amount (see Table 1). We need to mention that, due to some delay of the final publications of the experimental result [1] and theoretical calculations [10], no actual theoretical predictions have been published. Most of the presentations (conference and seminar talks and posters) dealt with unaccurate theoretical predictions because it was believed that nothing had been known on the two-loop corrections. However, that was not the case, because from the beginning of the theoretical calculations up to recent re-calculations it was clearly stated ed [6] that the (Za)2 term in Eq. (4) is of pure kinematic origin and so the result is valid in any order of the expansion in a for the anomalous magnetic moment of a free electron, and in particular... [Pg.654]


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See also in sourсe #XX -- [ Pg.155 ]




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