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Log reduction. Log reduction is a measure of how thoroughly a decontamination process reduces the concentration of a contaminant. It is defined as the common logarithm of the ratio of the levels of contamination before and after the process, so an increment of 1 corresponds to a reduction in concentration by a factor of 10.
Sterility assurance level. In microbiology, sterility assurance level (SAL) is the probability that a single unit that has been subjected to sterilization nevertheless remains nonsterile. It is never possible to prove that all organisms have been destroyed, as the likelihood of survival of an individual microorganism is never zero.
D-value (microbiology) In microbiology, in the context of a sterilization procedure, the D-value or decimal reduction time (or decimal reduction dose) is the time (or dose of an antimicrobial drug) required, at a given condition (e.g. temperature) or set of conditions, to achieve a one- log reduction, that is, to kill 90% of relevant ...
Because log(x) is the sum of the terms of the form log(1 + 2 −k) corresponding to those k for which the factor 1 + 2 −k was included in the product P, log(x) may be computed by simple addition, using a table of log(1 + 2 −k) for all k. Any base may be used for the logarithm table. [53]
(A log 10 reduction between 6 and 7 means that 1 bacterium out of 1 million (10 6) to 10 million (10 7) bacteria survive the treatment.) The Codex Alimentarius Code of Hygienic Practice for Milk notes that milk pasteurization is designed to achieve at least a 5 log 10 reduction of Coxiella burnetii. [48]
However, log-ratios are often used for analysis and visualization of fold changes. The logarithm to base 2 is most commonly used, [ 8 ] [ 9 ] as it is easy to interpret, e.g. a doubling in the original scaling is equal to a log 2 fold change of 1, a quadrupling is equal to a log 2 fold change of 2 and so on.
Z-value is a term used in microbial thermal death time calculations. It is the number of degrees the temperature has to be increased to achieve a tenfold (i.e. 1 log 10) reduction in the D-value. The D-value of an organism is the time required in a given medium, at a given temperature, for a ten-fold reduction in the number of organisms.
In computability theory and computational complexity theory, a reduction is an algorithm for transforming one problem into another problem. A sufficiently efficient reduction from one problem to another may be used to show that the second problem is at least as difficult as the first. Intuitively, problem A is reducible to problem B, if an ...