Potential return measures, limitations

The fundamental requirement of all radiation-transfer techniques in remote spectroscopy is that the radiation be transferred from the spectrometer to the sample, probe the reactions or transformations of interest and then return the modified beam of radiation to the spectrometer for the measurement of intensity at each wavelength in the spectral region of interest, all without any contributions from the transfer medium and with little loss in energy. While fibre-optics meets these requirements under favourable circumstances, there are potential artefacts and limitations, which may be understood from the principles of operation. 

A bond s yield is a measure of its potential return. Market participants commonly assess a security s relative value by calculating a yield or some yield spread. There are a number of yield measures that are quoted in the market. These measures are based on certain assumptions necessary to carry out the calculation. However, they also limit effectiveness of a yield measure in gauging relative value. In this section, we will explain the various yield and yield spread measures as well as document their limitations. 

There are several yield measures commonly quoted by dealers and traders in the bond market. Among the more prominent are current yield, yield to maturity, yield to call, yield to worst, and cash flow yield. In this section, we will demonstrate how to compute various yield measures for a bond given its price. We will also highlight their limitations as measures of potential return. 

EMIRS has been successfully applied to many systems. Briefly it can be mentioned the study of adsorbates at the electrode surface [10], the detection of adsorbed reaction intermediates for the oxidation of small organic molecules [12], and the determination of the water structure in the double layer [13]. However, the potential modulation in EMIRS is its drawback, since it prevents the study of irreversible processes as the system must return to the same conditions each time the potential is changed. Other important limitations of EMIRS are related to both the electrical and chemical relaxation effects caused by the potential modulation at 12 Hz. The electrical relaxation is due to the high ohmic drop of the electrolyte confined in the thin solution layer required for the in situ measurements. The chemical relaxation is due to ion migration induced by the change in solution composition caused by the electrode potential change. These aspects have been discussed in detail in the following text [14-16] (see Sect. 3.4.2.3). 

The real meaning of the LOD needs some clarifying. It is quite evident that repeating the measurements necessary for estimating an LOD would undoubtedly return a more or less different value. This because any LOD is simply a point estimate test statistic for the true LOD composite population parameter. Moreover, it is very probable that the real LOD distribution be skewed or abnormal, so that estimating the LOD on the basis of a hypothetical normal distribution is questionable. This potential limited reliability of LOD estimates justifies the use of the abovementioned, heavily approximated approaches. 

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