Slow mode artifacts

The PCS rate distribution shows only the large peak of the slow mode, corresponding to the high molar mass component. The tiny peak at Tl appears at too high rates and is probably an artifact. 

If, however, digital subtraction techniques should be applied to the central circulation, motional artifacts are caused by the contraction of the heart and even more by the respiration. The slow motion artifacts of respiration can be reduced by subtracting images which are separated by a short time interval (TID mode) thus leaving only the more rapid changes of the contrast material distribution related to the heart motion and blood flow. The contrast itself is thereby reduced, which can be compensated in part by higher amplification after background subtraction. 

The phenomenology of the slow mode is complex. Early suggestions that the neutral polymer slow mode arises from dust or other artifacts are clearly disproved by modern work. However, some systems apparently do not show a slow mode, so there is no reason to doubt early statements that no slow mode had been observed in particular systems(28). 

In Figure 3 It appears that the energy relaxation occurs on two time scales. First the system relaxes at a fairly rapid rate for a time up to approximately 10 ps. This Is followed by a much more gradual relaxation which Is still occurring at the end of our calculation at 45 ps. While at first glance this final extremely slow relaxation may seem like an artifact of this calculation, we have observed such behavior In calculations on many different ensembles (23). In addition, a least squares fit to the last 35 ps shows that the energy In the CO mode Is going down and the total... 

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