The near-threshold closure corrected long crack growth data compare favorably with small crack growth data.
Near-threshold closure is complex because multiple closure mechanisms are likely, including plasticity and oxide-induced crack closure.
Figure 2, on the other hand, compares the epidemic curves for the targeted class, targeted grade and whole school strategies at fixed closure-triggering threshold and closure duration parameters.
The Geospatial Information Authority of Japan defines the threshold for closure of a round-trip survey as e=2.5sqrt{S}, (1 where e is the threshold for closure of a round-trip survey (mm) and S is the distance (km) between two benchmarks.
We did not observe schools adopting formal thresholds for closure (for example a certain percentage of students identified as ill or absent), although these were used in Japan in Spring 2009 [ 53].
Type IV represents lack of statewide uniformity by introducing randomness in the threshold for closures at the individual school level: 1 to 3 cases, 1 to 5 cases, and 1 to 10 cases.
In the UK, soil contamination thresholds triggering closure or remediation of allotment and garden sites are based on precautionary principles, generating 'scares' that may negatively impact public health disproportionately to the actual health risks of exposure to toxins through own-grown food.
We observe a larger reduction for smaller values of the closure-triggering threshold and for longer closure durations.
On the question of prevalence threshold for school closure, these simulations offer no evidence to support school closures promptly at the earliest stage of an epidemic, given the need for an 8-week closure period and the typically unknown transmissibility of the virus during an epidemic.
Type II represents a local threshold for school closure based on a standard of 5 cases in any school at alternative closure durations of 1, 2, 4, 8, and 16 weeks.
Closures of 1 2 weeks or more, regardless of R0 or closure threshold, did not reduce attack rates but did delay the epidemic peak.
