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.

Example Input: Abstract: Four patients who had no oocytes retrieved during an IVF cycle were studied in an attempt to identify predictors of such an occurrence and suggestions for its cause. All 30 follicles aspirated in five cycles in these four women yielded no oocytes. One patient had two cycles that produced no eggs. The empty follicle syndrome may represent a new syndrome and a cause of infertility.
Example Output: Adult

Example Input: Abstract: Histopathologic studies of dermal dog bites revealed changes identical with those observed in distant gunshot skin entrance wounds and in a presternal skin stab wound made by a screwdriver. The similarity of the epithelial and collagen changes produced by these three totally different traumatizing, perforating agencies indicate that it is the bullet's penetrating and crushing power, and not its caloric content, that is responsible for the characteristic dermal collagen changes noted in these common injuries.
Example Output: Animal

Example Input: Abstract: Two patients had heavy metal intoxication resulting from industrial exposure to mercury vapors. One patient remained asymptomatic despite high urinary mercury levels. The second presented with a documented toxic reaction, including abnormal electromyograms and hematuria. Treatment was begun with 2,3-dimercaptopropane-1-sulfonate, and investigational drug used under Food and Drug Administration guidelines (IND 19,276). Use in both patients resulted in a dramatic change in excretion half-life of the mercury, from 33.1 days before treatment to 11.2 days during therapy. No significant toxic effects related to drug therapy were observed. Clearing of hematuria and reversal of electromyographic abnormalities were prompt in the symptomatic patient. Therapy with 2,3-dimercaptopropane-1-sulfonate was effective in these two patients.
Example Output:
Adult