Background: Resection offers the only chance of cure for hepatic colorectal metastases. However, preoperative staging does not always reliably detect unresectable disease. The aim of this study was to investigate the role that laparoscopy with ultrasound may have in detecting unresectable disease, thus sparing patients from unnecessary laparotomy with the associated morbidity and cost. Methods: A retrospective review of all patients considered for liver resection of colorectal metastases during a 3-year period was performed, analyzing factors likely to predict resectable disease, rates of resectability, and success of laparoscopic staging at detecting unresectable disease. Results: Of 73 patients with resectable disease on computed tomography, 24 were deemed to need laparos

This article presents the results of a two-year study of children's difficulties in learning the concept of recursion in Logo. A number of incorrect mental models of recursion identified in the study are described. These are classified into main groups: mental models associated with the interpretation of recursive procedures and those associated with the construction of recursive procedures. Misconceptions underlying the erroneous mental models are presented. Possible reasons for adopting these misconceptions are put forward.

A hierarchical-clustering technique was applied to data on the mastery of mathematical skills for the purpose of examining relationships among the skills. The data were obtained from two administrations of criterion-referenced tests to 715 pupils in Grades 1 to 4 in two Irish elememary schools toward the end of their school year. A clear hierarchical ordering of skills was obtained at each grade. An examination of groups of computation-related skills showing a high degree of consistency in their orderings across the two administrations suggested that factors considered in the formulation of the skills could account for some of the orderings obtained. The results highlight the value of cluster analysis as a tool for the preliminary analysis of relationships among mathematical skills.

Describes the use of the Keller systems and its results in a freshman chemistry course.

No abstract