Hair Manganese and Hyperactive Behaviors: Pilot Study of School-Age Children Exposed through Tap Water

BACKGROUND: Neurotoxic effects are known to occur with inhalation of manganese particulates, but very few data are available on exposure to Mn in water. We undertook a pilot study in a community in Québec (Canada) where naturally occurring high Mn levels were present in the public water system. Our objective was to test the hypothesis that greater exposure to Mn via drinking water would be reflected in higher Mn content in hair which, in turn, would be associated with increased level of hyperactive behaviors. METHODS: Forty-six children participated in the study, 24 boys and 22 girls, 6–15 years of age (median, 11 years). Their homes received water from one of two wells (W) with different Mn concentrations: W1: mean 610 μg/L; W2: mean 160 μg/L. The Revised Conners’ Rating Scale for parents (CPRS-R) and for teachers (CTRS-R) were administered, providing T-scores on the following subscales: Oppositional, Hyperactivity, Cognitive Problems/Inattention, and ADHD Index. RESULTS: Children whose houses were supplied by W1 had higher hair Mn (MnH) than those supplied by W2 (mean 6.2 ± 4.7 μg/g vs. 3.3 ± 3.0 μg/g, p = 0.025). MnH was significantly associated with T-scores on the CTRS-R Oppositional (p = 0.020) and Hyperactivity (p = 0.002) subscales, after adjustment for age, sex, and income. All children with Oppositional and Hyperactivity T-scores ≥ 65 had MnH > 3.0 μg/g. CONCLUSIONS: The findings of this pilot study are sufficiently compelling to warrant more extensive investigations into the risks of Mn exposure in drinking water

Etude des arbres hyperquaternaires

In this thesis we talk about point quadtrees which are a generalization of the binary search tree. First of all, we present a survey of hierarchical data structures such as pixel quadtrees, k-d trees, pseudo-quadtrees and pseudo k-d trees. Results concerning binary search trees are given as well as for point quadtrees. A study in depth allowed us to get interesting results about the depth of the last node inserted and the proportion of the different kind of nodes in a quad tree. Finally, we study the pseudo-quadtree which can be viewed as a good alternative of the original quadtree in the sense that it is more powerful for search, insert and delete points than its counterpart

Structures du français et ordinateur

Dugas André, Laforest Louise. Structures du français et ordinateur. In: Langue française, n°83, 1989. Langue française et nouvelles technologies, sous la direction de André Dugas. pp. 67-72

Around the root of random multidimensional quadtrees

We analyse the distribution of the root pattern of randomly grown multidimensional point quadtrees. In particular, exact, recursive and asymptotic formulas are given for the expected arity of the root

Hypergeometrics and the Cost Structure of Quadtrees

Several characteristic parameters of randomly grown quadtrees of any dimension are analysed. Additive parameters have expectations whose generating functions are expressible in terms of generalized hypergeometric functions. A complex asymptotic process based on singularity analysis and integral representations akin to Mellin transforms leads to explicit values for various structure constants related to path length, retrieval costs, and storage occupation