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A better algorithm is promulgated for the decrease of a quadratic action affected by zero-one aspects of quadratic constraints following the notion of additive penalties. By using negative variables, a quadratic function, wherein every coefficent but constant terms have nonnegativity, is found. The constant becomes a higher bound of the function. Properties are found based on a tighter bound, and workable testing is developed. A basic heuristic technique is used to find a tighter bound. Flexibility issues are considered. Extensive examples and formulations for the algorithm are included.

Two synthetic N-nitrosamines (N-3-methylbutyl-N-1-methyl acetonylnitrosamine and N-methyl-N-benzyl-nitrosamine), previously isolated from corn-bread which had been inoculated with moulds occurring in Linshien county, Northern China and subsequent nitrosation by sodium nitrite, were tested in strains TA1535 and TA100 in the presence of a liver postmitochondrial supernatant from Aroclor-treated rats. A concentration-dependent increase in the number of mutant colonies in both bacterial strains was observed when N-3-methylbutyl-N-1-methylacetonyl-nitrosamine was assayed in liquid suspension and N-methyl-N-benzylnitrosamine in plate incorporation assays. Our finding that mutagenic N-nitrosamines are present in foodstuffs that may be consumed in Linshien county are discussed in relation to the possible etlological role of these compounds in cancer of the oesophagus in that area. [ABSTRACT FROM PUBLISHER]