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Anomalies modeling effect

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]

A complication, however, arises from the fact that these anomalies are also due to proton nucleosynthesis (though operating at higher temperatures) and thus that some primordial CNO-abundance anomalies should be expected, too. In fact, 47 Tuc has been for a long time the example for a CN/CH dichotomy all along the cluster sequence, and by now, CN-variations have been found -mainly by Cohen, Briley and coworkers - in unevolved stars of other clusters as well (47 Tuc [3,2], M71 [1], M5 [9],. ..). This complicates the task to identify the purely evolutionary effect due to extra-mixing, which is needed to develop and test physical models. [Pg.301]

NMR studies on 28 and 29 indicate that both the thiophene and furan rings rotate freely at room temperature (vide infra) and therefore, anomalies in the UV spectra of 28 and 29 should be attributed to the through-bond interaction between the Si-Si cr bonds and aromatic 77 bonds. This was further confirmed by photoelectron spectral studies. As shown in Table II, the lift of HOMO for 12 relative to the model compound was 0.4 eV, but those for 28 and 29 were 0.7 and 0.6 eV, respectively. Apparently, more effective through-bond interaction occurs for 28 and 29 (21). [Pg.383]

The prediction of a heavy boson has received preliminary empirical support [92,96] from an anomaly in Z decay widths that points toward the existence of Z bosons with a mass of 812 GeV 1 33j [92,96] within the SO(l) grand unified field model, and a Higgs mechanism of 145 GeV4gj3. This suggests that a new massive neutral boson has been detected. Analysis of the hadronic peak cross sections obtained at LEP [96] implies a small amount of missing invisible width in Z decays. The effective number of massless neutrinos is 2.985 0.008, which is below the prediction of 3 by the standard model of electroweak interactions. The weak charge Qw in atomic parity violation can be interpreted as a measurement of the S parameter. This indicates a new Qw = 72.06 0.44, which is found to be above the standard model pre-... [Pg.215]

To model a complete stack, which may be constituted of more than 1000 cells, it is necessary to adopt a different approach. In this chapter a finite difference model is presented. Only energy equation and current conservation are solved. This allows one to examine possible improvements in the stack configuration design that can be achieved by taking advantage of the relation between temperature and elec-tronic/ionic resistivity, heat transfer and chemical reactions, etc. In addition, this model can be used for analyzing the effects of possible anomalies and performance degradation. [Pg.214]


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Anomaly

Modeling effect of anomalies

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