Definition: Given an abstract, generate a keyword (a noun phrase) that best describes the focus or contribution of the paper. Such keywords can be directly from the given abstract or outside it.
Input: Abstract: The incidence of air under the diaphragm in CAPD patients is very low, and causes directly attributable to standard CAPD techniques are even lower. Bowel perforation generally causes a larger volume of air collection under the diaphragm.
Output:
Air