On the other side, a tool like a hammer may become "present-at-hand", when it breaks and loses its usefulness, or, at the first encounter, when we do not know how to interact with it.
If there are multiple CD4 determinations, the Track-shot rule can be used later on, but loses its usefulness once intra-individual variability makes it likely that an immediately retested CD4 count will reach the treatment threshold.
But even for a trajectory defined with high precision by numerous points, this rule loses its usefulness once intra-individual variability makes it possible for the next point to reach the threshold (respectively below 430, 640, and 840 for the three thresholds at P = 0.05, and 370, 570, and 755 at P = 0.1).
As before, as CD4 counts come near to the decision threshold, this rule loses its usefulness and frequent CD4 monitoring becomes necessary.
The rule loses its usefulness in the presence of low to intermediate CD4 counts (below 550, 785, and 1000×106/L for the three respective decision thresholds at P = 0.05, and below 460, 675, and 880×106/L at P = 0.1).
If the observation at this time does not reach the decision threshold, the rule can be applied recursively and will estimate shorter and shorter intervals until the rule loses its usefulness; then either the Track-shot rule below or frequent CD4 monitoring become necessary.
DRIN, being an early marker of renal involvement, probably loses its usefulness with disease progression.
"It has lost its usefulness as a focal center of high-level debate about Democratic policy".
Since traffic congestion occurs during a relatively long period of time it can be aggregated within 5 minutes (300 seconds) periods without losing its usefulness and relevance.
But the tool has lost its usefulness.
