Target frequencies

Among MSPs from the comparisons of two random sequences using the scores. v, , residues a, and a will be aligned with target frequency... 

Substitution matrices have also been modeled on amino acid or protein structural properties rather than on alignment data (Grantham, 1974 Miyata et al., 1979 Rao, 1987). However, the relationship between scores and target frequencies means that any imaginable set of scores has an implicit set of target frequencies, and obtaining these from the alignment data itself is the most direct approach (Altschul, 1991). 

Deng, C.X. and Capecchi, M.R. (1 992) Re-examination of gene targeting frequency as a function of the extent of homology between the targeting vector and the target locus. Molecular and Cellular Biology 12, 3365-3371. 

A gene fragment used to construct a targeting vector should be cloned from the same mouse strain as the ES cells to reduce the effect of polymorphic variation, since polymorphic variation between the vector and the chromosome of the ES cell may significantly decrease the targeting frequency. 

An easy and effective screening strategy has to be considered when designing a knockout vector. Two methods have been successfully used, PCR and Southern blot analysis. The advantage of PCR is that a large number of samples can be screened in a short time. For experiments with very low targeting frequency,... 

The BFOSUM substitution matrices have been constructed in a similar fashion, but make use of a different strategy for estimating the target frequencies (Henikoff and Henikoff, 1992). The imderlying data are derived from the BFOCKS database (Henikoff and Henikoff, 1991), which contains local multiple alignments ( blocks )... 

The required safety integrity level of the instrumented function shall be derived by taking into account the required risk reduction that is to be provided by that function. For those SILs, the target PFDj,yg on demand and the target frequencies of dangerous failure are hsted in Table 3.8 [ANSI/ISA-84.00.01(2004) Part 3] for each SIF. Several risk analysis methods ranging from qualitative to fully quantitative can be deployed based on the severity and complexity of the scope, as listed in Table 3.9. 

Table 3.8 Safety integrity levels probability of failure on demand, target risk reduction factor and target frequency of dangerous failure to perform the SIF.

Forklift Accident During Movement of an Irradiated Target Frequency Bin lll-IV, 10 2>F>10" (Unlikely)-10" > F > 10" (Very Unlikely) <1 mrem unmitigated YES... 

The specimen is subjected to a sinusoidal force, at the target frequency 5%, applied at the head of the specimen from a time of 30 s (minimum) to a time of 2 min (maximum) to an imposed deflection corresponding with a strain, e, less than 50 microstrain (pm/m). 

Safety integrity level (SIL) Target frequency of dangerous failures to perform the safety instrumented function (per hour)... 

For years, safety workers have been targeting frequency in the belief that severity would be reduced as a by-product. As a result, in Australia for example, Freqrrency Rates nationwide have been reduced much more than have Severity Rates. One Australian state reported a 33% reduction in all accidents over a period of 10 years while, dttring the same period, the number of permanent partial disability injrrries actualfy increased. (This cotdd have resulted from a statistical recording change rather than arty real improvemerrt in accident rates.)... 

The Severity Level may be expressed in semi-quantitative terms, with target frequency ranges (see Table 6),... 

Zhang, H, Hasty, P, and Bradley, A (1994) Targeting frequency for deletion vectors in embryonic stem cells. Mol. Cell Biol. 14, 2404-2410. 

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