Post-baseline correction

Exspline is an X-window-based program that uses spline first for pre- and postedge fitting baselines. It has the advantage that the Fourier transform, the EXAFS and the pre- and post- baseline fit can be observed interactively. This is a great improvement on Exback, which used non-interactive baseline correction. 

The signal quality (= low detector noise) and sample rate should be sufficiently high to obtain correct results, otherwise post processing of the data is necessary, such as smoothing, baseline correction, etc. Even then the result of the integration in Eq. 6.126 depends very much on the extension of the baseline, and the obtained value of the second moment can be very inaccurate (Chapter 2.7, Section 6.5.3.3). 

The issue here is not just one of simplicity versus complexity. My personal view is that in the use of covariates and measurements generally there is much to be gained by using more complex models. This was the view as regards use of baselines and other covariates expounded in Chapter 7. The issue here, however, is to do with modelling of the relationship between outcome measures themselves rather than between outcome measures and baselines. This raises the problem of correction for post-baseline covariates. 

Figure 11 shows the low-frequency fling for record TCU129EW after the application of the undecimated wavelet transform, before and after baseline correction. There is clear post-fling... 

Post-processing of NMR spectra is a multistage procedure basically comprising Fourier transform, phase correctimi, and baseline correction. Each of these steps can be done automatically but, since they can greatly influence... 

Blood AChE-inhibition The mean blood AChE-inhibition after pretreatment, measured as a percentage of the baseline value, was 20-35 % (see Table 2). The AChE-inhibition measured one hour after soman followed by a post-intoxication therapy, was significantly lower in all groups (t-test with Welch s correction, p < 0.05). The inhibition of AChE after soman was less in animals pretreated with PYR or with PHY combined with PC (resp. 85.5 1 % and 89.4 2 %). 

Before the advent of Fourier transform spectrometers, wide-line NMR was done by sweeping the magnetic field and observing the dispersion signal, or by pulsing the radiofrequency and observing the free Induction decay without transformation. The very broad spectral widths have caused problems with baselines and faithful representations of the entire llneshapes. Various techniques, such as the quadrupole echo (lA), progressive phase alternation of the excitation pulse and detector, short spectrometer dead times, and post-acquisition spectral correction (15) have circumvented most of these. 

Wavelet Domain Seismic Correction, results of an acceleration transient gO at 4S.6S s. The Fig. 9 TCU068NS low-frequency sub-band fling, which resulting constant velocity DC shift of 11.61 cm/s is shows results before (red) and after (blue) baseline cor- shown in light gray as a post-shaldng, flat velocity time... 

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