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: A national survey of pain in the United States has been conducted, using a sample of 1254 persons 18 years of age or more, statistically constructed so as to permit projections to be made to the entire adult population of 174 million with a predicted accuracy of +/- 2-3%. Pain prevalence and severity, and its impact on work and other activities were obtained and correlated with demographic variables. This paper reports the portion of the study examining the association of pain with stress, daily hassles, measures of health locus of control, and various health habits. There was a very strong association between stress and pain and hassles and pain. The greater the stress and hassles, the greater the incidence, frequency and severity of all pains reported. Those with high internal health locus of control are more likely to have healthy behavior, are less likely to have all kinds of pain, and have less severe pain. Stress was voluntarily mentioned by respondents as a major cause of pain in headaches, backaches, stomach pains, and menstrual pains, but not for muscle, joint or dental pains.
Example Output: Adult

Example Input: Abstract: We have previously reported that lymph from the chronic sheep lung lymph preparation contains 25-60% lymph from nonpulmonary sources. In subsequent studies we found that the lymph flow rate from cannulated lymph vessels depends on the resistance and position of the lymph cannula. Because we did not account for these factors in our estimate of the amount of nonpulmonary lymph in the sheep lung lymph preparation, our data were not accurate. We probably overestimated the amount of nonpulmonary lymph. However, the presence of nonpulmonary lymph remains a potentially serious problem with the sheep lung lymph preparation.
Example Output: Animal

Example Input: Abstract: A 9-year review of our experience with head and neck metastases from 845 urogenital tract tumors of the kidney, prostate, bladder, testicle, spermatic cord, penis, urethra, and ureter was performed. Thirty-one (3.7%) of these tumors developed metastases to the cervical and supraclavicular lymph nodes, scalp, thyroid gland, thyroid cartilage, parotid gland, retroorbit, mandible, nasal cavity, and paranasal sinuses. Unusual cases and a review of the literature are presented. The frequency of such metastases to the head and neck from various primaries, diagnostic application of current immunohistochemical methodology, and therapeutic alternatives are emphasized.
Example Output:
Adenocarcinoma