We consider the integration of the special second‐order initial value problem of the form
y′′=ffalse(x,yfalse). A recently introduced family of 7 stages, eighth‐order methods, sharing constant coefficients, is used as base. This family is properly modified to derive phase fitted and zero dissipative methods (ie, trigonometric fitted) that are best suited for integrating oscillatory problems. Numerical tests over a set of problems shows enhanced performance when the purely linear part of the problems is rather large in comparison with the rest of nonlinear parts. An appendix implementing a MATLAB listing with the coefficients of the new method is also given.
During 1992 and 1993, 309 children aged 1-22 months (mo) and their mothers visiting an immunization facility in Al Ain city, Abu Dhabi Emirate, United Arab Emirates, were studied to (1) define blood haemoglobin (Hb) levels; (2) estimate the prevalence of anaemia; (3) examine the role of iron deficiency in causing anaemia; (4) identify the correlates of anaemia prevalence; and (5) assess the acceptability to parents of an anaemia screening test for their young children. The levels of Hb in all subjects and the levels of serum ferritin in anaemic (Hb < 11 g/dl) children aged > or = 6 mo and in non-pregnant women with Hb < 11 g/dl were determined by a HemoCue Photometer and an enzyme immunoassay, respectively. Each woman was interviewed to obtain pertinent data. In children, anaemia was detected in 3% of those aged 1-2 mo (Hb < 9 g/dl), in 8% of those aged 3-5 mo (Hb < 10 g/dl), and in 25-39% of those aged > or = 6 mo (Hb < 11 g/dl). Of 19 children tested, ten (53%) were iron-depleted (serum ferritin < 12 micrograms/l). After multivariate adjustment, the only significant positive correlate of anaemia in children was older age (1-5 mo vs 6-22 mo; odds ratio [OR]: 9.51; 95% confidence interval [CI]: 3.92-23.08). Anaemia was detected in 14% of pregnant women (Hb < 11 g/dl) and 16% of non-pregnant women (Hb < 12 g/dl).(ABSTRACT TRUNCATED AT 250 WORDS)
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