Ambiguity resolution

Rindflesch, T. C., and A. R. Aronson. 1994. Ambiguity resolution with mapping free-text to the UMLS metathesaurus. J Am Med Inform Assn 240-4. 

Enantioresolution in capillary electrophoresis (CE) is typically achieved with the help of chiral additives dissolved in the background electrolyte. A number of low as well as high molecular weight compounds such as proteins, antibiotics, crown ethers, and cyclodextrins have already been tested and optimized. Since the mechanism of retention and resolution remains ambiguous, the selection of an additive best suited for the specific separation relies on the one-at-a-time testing of each individual compound, a tedious process at best. Obviously, the use of a mixed library of chiral additives combined with an efficient deconvolution strategy has the potential to accelerate this selection. 

The lipophilicity of the TRISPHAT anion 8 also confers to its salts an affinity for organic solvents and, once dissolved, the ion pairs do not partition in aqueous layers. This rather uncommon property was used by Lacour s group to develop a simple and practical resolution procedure of chiral cationic coordination complexes by asymmetric extraction [134,135]. Selectivity ratios as high as 35 1 were measured for the enantiomers of ruthenium(II) trisdiimine complexes, demonstrating without ambiguity the efficiency of the resolution procedure [134]. 

The picture of cement microstructure that now emerges is of particles of partially degraded glass embedded in a matrix of calcium and aluminium polyalkenoates and sheathed in a layer of siliceous gel probably formed just outside the particle boundary. This structure (shown in Figure 5.17) was first proposed by Wilson Prosser (1982, 1984) and has since been confirmed by recent electron microscopic studies by Swift Dogan (1990) and Hatton Brook (1992). The latter used transmission electron microscopy with high resolution to confirm this model without ambiguity. 

R. Tauler, A.K. Smilde and B.R. Kowalski, Selectivity, local rank, three-way data analysis and ambiguity in multivariate curve resolution. J. Chemom., 9 (1995) 31-58. 

Figure 30 shows the potential of the 10-ppm approach. The full-width HMBC spectra (left) do not allow a clear discrimination of all cross-peaks. For instance, the correlation between the proton resonance of CH3fi2 MeLeu 9 at 0.82 ppm and the close pair of carbons at 22.1 and 22.2 ppm remains ambiguous and it is not possible to attribute the resonance of the CF c) MeLeu 9. In the 10-ppm spectrum, the achieved resolution clearly shows that this correlation can be unambiguously attributed, and that the exact resonance of the CHyh MeLeu 9 is 22.2 ppm. 

Numerous new developments and applications of solid state NMR techniques have emerged. Multidimensional NMR methods are able to probe connectivity patterns of zeolite framework structures and solve ambiguities in line assignments [27], high-resolution techniques for quadrupolar nuclei have been developed [31-34], and powerful double-resonance methods permit the study of spatial... 

Computation of this function results in a three-dimensional plot for which one axis is time delay (or range), the second is Doppler frequency or radial velocity and the third is the output power of the matched filter (usually normalised to unity). The extent of the ambiguity function peak in the Tr and the fd dimensions determines the range and Doppler resolutions respectively. As we are using the directly received signal only we term this self-ambiguity as there is no inclusion of any system geometry dependence on the transmitter and receiver locations. 

The outcome of this procedure will be the same as in the previous case in terms of the system s parameters (resolution and ambiguity), but not exploited via centralized processing as the ambiguity function seen by each receiver will be individually different. 

The left plot represents the cuts of the bistatic ambiguity function of the first bistatic pair, in the absence of the second transmitter. Adding the emitter, and for this topology where the two weighting factors are comparable, the resolution in range and velocity has improved significantly. Moreover, the ambiguity peaks are suppressed. 

---