Exposure to lead and specific attentional problems in schoolchildren.

A pilot study was carried out to investigate the relationship between exposure to lead and attention in children. The participants were 43 boys, 8 to 12 years of age, attending special schools for children with educational and/or learning problems (so called LOM schools). Children with probable causes of attentional or memory problems other than lead contamination were excluded from the study.

Nutrient intake and biological maturation during adolescence. The Amsterdam growth and health longitudinal study.

The study evaluates the association of the food intake and the rate of biological maturation of 200 boys and girls in Amsterdam during their adolescence. The subjects were followed in a longitudinal survey over a period of 9 years, between the ages of 13 and 22 years. In the first four years (1976-1980) annual measurements were performed (school period).

Learning the cascade juggle: a dynamical systems analysis.

How beginning jugglers discover the temporal constraints governing the juggling workspace while learning to juggle three balls in a cascade pattern was the subject of this investigation. On the basis of previous theoretical and experimental work on expert jugglers, we proposed a three-stage model of the learning process, for which objective evidence was sought. The first stage consists of learning to accommodate the real-time requirements of juggling, as expressed in Shannon's equation of juggling, which states that, averaged over time, the cycle time of the hands should be a fixed proportion of the cycle time of the balls.

Molecular characterization of a nonautonomous transposable element (dTph1) of petunia.

An insertion sequence of 283 base pairs has been isolated from the DFR-C gene (dihydroflavonol-4-reductase) of petunia. This insert was found only in a line unstable for the An1 locus (anthocyanin 1, located on chromosome VI) and not in fully pigmented progenitor and revertant lines or in stable white derivative lines. This implies that the An1 locus encodes the DFR-C gene.