Difficulties and ambiguities

After a substantial range of examples of EIMS mass spectra of peptides had accumulated, it became clear that difficulties and ambiguities of interpretation could be expected (Anderegg et al., 1976). Applications of EIMS methods declined, as softer ionisation methods - such as fast-atom bombardment (FAB) MS - became established (Biemann and Martin, 1987 Biemann, 1989). These methods create less-energetic molecular ions and the ensuing fragmentation is therefore less extensive (this usually ensures the presence of an intense molecular ion peak in the spectrum) and spectra are therefore more easily interpreted. 

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Some of the difficulties and ambiguities presently plaguing carbon dioxide coordination chemistry are illustrated in the following summaries of re-... 

This skepticism was engendered by the difficulties and ambiguities in studying very transient intermediates, and the impossibility (at the time at least) of observing transition states. 

Wolfgang and Cross [47] have suggested that the difficulties and ambiguities in the transformation of /lab to /C TO. could be avoided if results were presented as probability functions in Cartesian coordinates defined by... 

The diagnosis of iron deficiency has its difficulties and ambiguities. Severe iron deficiency can be detected easily by the marked reduction in hemoglobin concentration, mean corpuscular hemoglobin and decreased serum iron concentration. However, in mild iron deficiency hemoglobin concentration, transferrin saturation, and serum ferritin levels are frequently normal in patients with depleted bone... 

The beauty of the ultrasonic method lies in this possibility of picking out how many equilibrium processes are present, and multistep equilibria can often be disentangled with relative ease. This is something which the other methods are either incapable of, or which they can only do with difficulty and ambiguity. 

Despite difficulties and ambiguous solutions, the spectropolarimetric method is the only way of determining the spectral values of the real part of the refractive index. In addition, the particle size distribution and the optical thickness of the gas layer overlying the cloud layer are estimated more accurately. Furthermore, it is reasonable to expect that polarimetric methods will be more successful in the study of the physical characteristics of surface layers for atmosphereless celestial bodies. For this purpose it is necessary to obtain high-precision polarization measurements with an error smaller than 0.05%. 

Section F.6.4 is devoted to superparamagnetic relaxation in zero applied field. Because the phenomena cannot be interpreted in details without a lineshape model, most representative models are surveyed. Their applicability to realistic situations is discussed. The exploitation of the magnetic splitting at low temperature and the determination of the blocking temperature are discussed. The difficulties and ambiguities in interpreting the Mossbauer spectra of actual samples are emphasized. 

The classical quotation which accurately conveys the level of our understanding of hardness compares the subject to our appreciation of the storminess of the seas . Both are readily appreciated but less easily quantified. Hardness measurements and their interpretation are fraught with difficulties and ambiguities. This is particularly so for organic polymers. The potential value of these measurements is, however, enormous and well proven in metallurgy. Hardness studies have... 

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