The Gamma Knife is a device used in stereotactic radiosurgery to produce precise lesions in specific areas of pathologic tissue in deep-seated central nervous system structures. The apparatus uses 201 beams of gamma radiation, which are carefully aimed to converge on a specific intracranial target, to kill cancer cells, shrink tumors, and treat vascular anomalies while sparing surrounding healthy tissue. What specialized equipment do patients wear during treatment?
Jerome K. Jerome
Back in the day
The phrase "Iron Curtain" refers to the political, military, and ideological barrier erected by the USSR after WWII to seal itself and its dependent eastern European allies off from contact with the West. Churchill's use of the phrase in a 1946 speech at a US college, though initially perceived as antagonistic, popularized the term. The Iron Curtain largely ceased to exist in 1990, when the communists of eastern Europe finally abandoned one-party rule. What are some earlier uses of the phrase?
Born on a day like today
Mercator was a Flemish geographer, mathematician, and cartographer who perfected the first map using the Mercator projection, the translation of the spherical earth to a two-dimensional flat plane. In it, parallels and meridians are rendered as straight lines spaced to produce an accurate ratio of latitude to longitude at any point. It permits mariners to steer a course over long distances without continually adjusting compass readings. What map-related term was coined by Mercator?