A new upper bound is provided for the L ∞-norm of the difference between the viscosity solution of a model steady state Hamilton-Jacobi equation, u, and any given approximation, v. This upper bound is independent of the method used to compute the approximation v; it depends solely on the values that the residual takes on a subset of the domain which can be easily computed in terms of v. Numerical experiments investigating the sharpness of the a posteriori error estimate are given.
SYNOPSIS The neutrophilic alkaline phosphatase activity of 40 newborns was determined and found to be frequently raised, similarly to a leukaemoid reaction. The newborn neutrophil has strong alkaline phosphatase activity and is unlike the myeloid leukaemia cell which has no alkaline phosphatase activity.We have recently been interested in investigating various enzyme activities in leukaemic cells. It has been established that neutrophils in chronic myeloid leukaemia have decreased or absent alkaline phosphatase activity (Kaplow, 1955; Wiltshaw and Maloney, 1955). Furthermore, studies have demonstrated that in neutrophils the alkaline phosphatase activity is raised in leukaemoid states due to various aetiologies, polycythaemia rubra vera, and in extraand intrauterine pregnancy.It is possible that the adult leukaemic myeloid cell may represent an immature cell such as is found in newborn infants. In this study, the problem was to ascertain if the newborn neutrophil possessed alkaline phosphatase activity.
METHODS AND MATERIALSWe studied 40 newborns (first week of life). The infants were equally divided into male and female and Caucasian and Negro groups. The Kaplow (1955) 6 Place in dilute ammonium sulphide for five minutes (1 5 % NH4S). 'Present address:
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