introduction: in traditional medical education systems much interest is placed on the cramming of basic and clinical facts without considering their applicability in the future professional career. the aim of this study is to evaluate a novice medical training method (problem-based learning) as compared to the contemporary teacher-based medical education or traditional methods. methods: selecti...

in this paper, at rst for a given set of real or complex numbers  with nonnegative summation, we introduce some special conditions that with them there is no nonnegative tridiagonal matrix in which  is its spectrum. in continue we present some conditions for existence such nonnegative tridiagonal matrices.

An employee transporting problem is described and a set partitioning model is developed. An investigation of the model leads to a knapsack problem as a surrogate problem. Finding a partition corresponding to the knapsack problem provides a solution to the problem. An exact algorithm is proposed to obtain a partition (subset-vehicle combination) corresponding to the knapsack solution. It require...