Downward progression

For components or devices supplied hy outside manufacturers, usually the downward progression is stopped at the component level, unless the device is normally opened, repaired, calibrated, adjusted, or inspected hy in-house personnel. Electronic hlack boxes (similar to those under the hood of our automobiles) are good examples. We as owners may have occasion to manipulate the connection points (wires, attachment, and securing brackets), but we do not open nor usually attempt to diagnose an internal malfunction of these devices. For work on our automobile electronics black boxes, we turn to specially trained experts who use special equipment. 

Idnurm and Schmidt, 1986 Acton and Kettles, 1996). Elsewhere, magnetostratigraphy (the record of dated reversals in the Earth s magnetic field) has been applied to trace the timing of downward progression of the weathering front (e.g. Pillans, 1997 Theveniaut and Freyssinet, 1999). 

Downward progressing sulfidization fronts have also been reported to be initiated by transitions from limnic to brackish/marine conditions in the Baltic Sea (Bottcher and Lepland 2000 Neumann et al. 2005) and the Black Sea (Jorgensen et al. 2004 Neretin et al. 2004). In contrast to the example from the Eastern Mediterranean presented above, the sulfide driving the downward sulfidization in these sedimentary settings is derived primarily from AOM and from the increase in sulfate concentration in the water colunrn during the Holocene. At the sites on the western continental slope of the Black Sea investigated by Jorgensen et al. 

Fig. 8.15 Sulfur geochemistry of a 4-m deep sediment core from the upper slope of the western Black Sea. Left frame SO , H S, CH and Fe + (notice scales) in the pore water. The smooth curves are model fits to the data based on the PROFILE model (Berg et al. 1998). Right frame Chromium reducible sulfur (CRS) and acid volatile sulfide (AVS), the latter showing the black band of iron sulfide at 250-300 cm depth due to the downward progressing sulfidization front. From Jorgensen et al. (2004).

A first idea of a non-incremental stepwise synthesis strategy (with a fixed, finite number /of predefined steps) is to achieve downward progression ... 

The non-incremental synthesis strategy above can now be refined as follows, so as to achieve simultaneous upward and downward progressions [Flener and Deville 92,93ab] ... 

Figure 3.4-10 Visualization of the downward progress of a coherent molten mass as the below-core structures weaken...

An indication of the effectiveness of the Trench Excavators Protection Act and its enforcement is the steady downwards progression of the fatality count in the eight-year period of its existence. There has been a steady decline from about eight a year to one and a half per year. This is representative of the decline in the count of lost-time iqjuries which has followed the same general pattern. 

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