Correlation quality analysis

With regards to the analysis of the quality of the various parts of the model, one may use the same methods as are used for practical identifiability analysis. Since the same methods are used, albeit with different objectives, one sometimes refers to this model quality analysis as a posteriori identifiability (and the previous analysis as a priori identifiability). Now, however, one is also interested in how the parametric uncertainty translates to an uncertainty in the various model predictions. For instance, it might be so that even though two individual parameters have a high uncertainty, they are correlated in such a manner that their effect on a specific (non-measured) model output is always the same. Such a translation may be obtained by simulations of the model using parameters within the determined confidence ellipsoids. A global alternative to this is to consider the outputs for all parameters that correspond to a cost function that is below a certain threshold, for example 2% above the found minimum. 

Laser Fluorimeter As 2i source of biological information we propose the use of a multi-station (up to 12 sampling locations) towed sea water laser fluorimeter for water quality analysis specific to selected hydrocarbons which might be present in the area. The laser excites elements of the plankton population and that of calibrated hydrocarbons (e.g. breakdown products of munitions contents) present in the water. The fluorescent spectra are received through a fibre optic cable, split and counted through specific filters. From this data a direct correlation of the effects of pollution on the plankton population can be made. The system would be towed in conjunction with the multi-sensor towed array. 

The quality analysis of ESR spectra was pursued by using the ratio of intensities of two first low-field peaks, and P, belonging to slow and fast rotation, respectively (see Figure 11.3B). Additionally the spectrum characteristic was selected as the distance between the first peak and the third one (L) in single triplet that identifies mobility in denser areas of amorphous phase. In ESR spectra comparison the value L for the bulk film of PHB (50 Gs) was slightly less than for the fibers (62 Gs) that allows one to suggest slower rotation of the probe in denser field of the fiber mat than in the same field of the PHB film. The distinction between behaviors of two probe populations in the film are more noticeable than in the fiber mates. In fact the ratio I VI in the rolled mats has higher value (0.52) as compared with the initial fiber mats (0.37). The difference in peak intensities shows that effective correlation time in the fibers (3.5x 10 s) exceeds the same characteristic in the film (1.36x I0 s) that also indicates the slow molecular mobility in the low-dense amorphous fraction of PHB rolled fibers as compared to the film. 

First, the structure should explain the data. Apart from the energy or target function value returned by the refinement program, this check can be performed with some independent programs (e.g., AQUA/PROCHECK-NMR [90], MOLMOL [91]). The analysis of the deviations from the restraints used in calculating the structures is very useful in the process of assigning the NOE peaks and refining the restraint list. As indicators of the quality of the final structure they are less powerful, because violations have been checked and probably removed. A recent statistical survey of the quality of NMR structures found weak correlations between deviations from NMR restraints and other indicators of structure quality [88]. 

Encouraged by this spectral reproducibility, we focused our efforts on the particularly challenging problem of distinguishing bacterial strains by MALDI MS. We developed a modified correlation approach22 that relies on two fundamental qualities of bacterial mass spectra. First, because different bacterial strains of the same species have substantial, if not complete, genetic overlap, most of the protein masses observed with two different strains will be identical. This feature limits the value of the biomarker approach that is commonly used to differentiate bacteria species. Second, as just noted, closely controlled sample preparation and mass analysis procedures can result in highly reproducible results.22 The modified correlation approach takes advantage of subtle, yet reproducible, differences in mass spectra obtained from dif-... 

The above analysis reveals that some of the thermochemical data for organotin compounds may not be as accurate as one could hope. Although the information is in general of much better quality than in the case of germanium and lead analogues, we believe that some values in Table 3 should be redetermined. Other examples could have been used to illustrate this point (see also the next section), but once again we wish to resist the temptation of recommending data that in some cases conflict with the available experimental results. By a judicious use of the Laidler terms in Table 4 and/or correlations similar to those in equation 2, it is rather simple to assess other values from Table 3 and predict new data. 

The procedure described, involving the variation of the laser energy, has some advantages relative to the alternative method of using several solutions with different transmittances. First, it provides a check for multiphoton effects simply by analyzing the quality of the linear correlations obtained. It should be stressed that the excellent correlations in figure 13.7 are typical, that is, correlation factors are usually better than 0.9995. Second, the method requires considerably less sample (only one solution is needed). Third, the analysis of experimental data is also conceptually simpler, because no normalization is required. 

Calibration curve quality. Calibration curve quality is usually evaluated by statistical parameters, such as the correlation coefficient and standard error of estimate, and by empirical indexes, such as the length of the linear range. Using confidence band statistics, curve quality can be better described in terms of confidence band widths at several key concentrations. Other semi-quantitative indexes become redundant. Alternatively, the effects of curve quality can be incorporated into statements of sample analysis data quality. 

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