This study attempts to specify the relational calculi that young students elaborate for solving compare problems, which have been identified as being among the most difficult of the addition problems. Based on an integration of hypotheses and models from research attempting to account for problem-solving activity on these problems, an a priori analysis makes explicit the relational calculi capable of leading to the solution of six compare problems. This analysis provides a foundation for an analysis ofprotocols, which were collected from 25 first-grade students solving and reformulating compare problems. The results highlight the dynamic character of the structuring and arithmetizing processes in setting up the relationships within a problem. Thus, the numerical calculi employed are interpreted as a function of the structure of the problem and, in turn, the situation described by the problem derives its meaning from a knowledge of the arithmetic operations activated by the numerical calculi.
A case of an intradural extramedullary meningioma of the cervical spine excised through an anterior approach is reported. This permitted a complete excision without manipulation of the cord followed by a rapid and complete recovery. The technique of excision and bone grafting is described.
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