Naming difficulties may be rank ordered along a continuum. Items are rank ordered in terms of their ability to be named, which is correlated with their frequency. This type of picture-naming test is also useful in the examination of children with learning disabilities and the evaluation of brain-injured adults.
The Jarvik-7 heart was developed by American scientist Robert Jarvik and his mentor, Willem Kolff. In 1982, Seattle dentist Dr. Barney Clark was the first person implanted with the Jarvik-7, the first artificial heart intended to last a lifetime.
The first artificial refrigerator was invented by renowned Scottish physician William Cullen in 1755. After the cumbersome device produced a small amount of ice through delicate, manual labor, refrigeration technology was deemed impractical and was not further advanced for decades.