Fine needle aspiration of the breast. A probabilistic approach to diagnosis of carcinoma

European signing policy favours uncontrolled intersections--a trend which is in marked contrast to the U.S.A. policy. European drivers must constantly keep in mind the general rule of priority at cross-roads which requires one to yield to a vehicle coming from the right, if not otherwise indicated. For a European driver, an uncontrolled junction means an obligation to yield to vehicles on the right while for U.S. drivers, adapted to the U.S.A. system with more frequent signing, an intersection unsigned from his direction suggests priority for him, particularly in an urban area. To demonstrate a safety problem which follows, three American subjects, visiting professors without previous experience of driving in Europe, were asked to drive a 1.8 km route six times with an instrumented car in the downtown area of Helsinki. All of them first showed unsafe driving practices at uncontrolled intersections with restricted visibility in comparison to a local control group, but changed their strategy, both in terms of speed control and visual search, after they had been informed of the European rule of crossroad priority. In spite of the same general rule at blind intersections in a similar urban environment, a different signing policy may cause safety problems for American drivers in Europe, and translate into more accidents at non-priority intersections. Varying rules and practices in different jurisdictions call for further efforts in presenting vital information to foreign motorists and striving towards worldwide uniform traffic control.