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: This prospective study evaluated the use of basic vital signs, two mechanisms of injury, and time-distance factors as field triage criteria for on-scene helicopter transport of 130 patients to a trauma center serving a rural area. The vital signs criteria included any one or more of the following: level of consciousness (LOC) less than or equal to unresponsive to verbal stimulation; respiration rate (RR) less than or equal to 10 or greater than or equal to 30; systolic blood pressure (BP) less than or equal to 90; pulse (P) less than or equal to 60 or greater than or equal to 120. The flight crew recorded vital signs taken by the first responder capable of basic assessment. Entrapment and associated fatalities in motor vehicular accidents were recorded and flight logistics were examined. The presence of one or more abnormal signs identified a group of seriously injured trauma patients (mean Injury Severity Score = 29.1) with 24% mortality compared to a predicted mortality of 32% (p less than 0.02). Unresponsiveness to verbal stimulation in the field was the single most predictive criterion, yielding sensitivity of 93% and specificity of 85%. Time-distance criteria were helpful to determine helicopter use.
Example Output: Adolescence

Example Input: Abstract: To study the relationship between lung weight and lymph flow, we used an in situ, isolated sheep lung preparation that allowed these two variables to be measured simultaneously. All lungs were perfused for 4.5 h at a constant rate of 100 ml X min-1 X kg-1. In control lungs, the left atrial pressure (Pla) was kept at atmospheric pressure. In experimental lungs, Pla was kept atmospheric except for a 50-min elevation to 18 mmHg midway through the perfusion. During this period of left atrial hypertension, pulmonary arterial pressure rose from 18 to 31 mmHg, lymph flow rose from 3 to 12 ml/h, and the lymph-to-plasma oncotic pressure ratio (pi L/pi P) fell from 0.7 to 0.48. After left atrial pressure was returned to control, pulmonary arterial pressure, lymph flow, and pi L/pi P all returned to control levels. The rate of weight gain after the return of left atrial pressure to control was also the same as that in the control group. However, during the period of left atrial hypertension 135 ml of fluid were filtered into the lung, and this large increase in lung weight remained after the pressure was lowered. The presence of this substantial excess lung water despite control values for vascular pressures, lymph flow, rate of weight gain, and pi L/pi P suggests that the absolute amount of lung water has little influence on the dynamic aspects of lung fluid balance. These results are consistent with a two-compartment model of the interstitial space, where only one of the compartments is readily drained by the lymphatics.
Example Output: Animal

Example Input: Abstract: The role of the second messengers cAMP and Ca++ in the control of proopiomelanocortin (POMC) gene expression was investigated with the use of hybridization with cloned complementary DNA probes. The effects of cAMP-related drugs on POMC messenger RNA (mRNA) levels were assessed in primary cultures of intermediate (IL) and anterior rat pituitary cells maintained in serum-free medium. 8-Bromo-cAMP (1 mM), but not 8-bromo-cGMP (1 mM), induced a 2-fold increase in IL and anterior lobe cell after 2 days of treatment. A similar increase was obtained with the adenylate cyclase-activating drugs forskolin (1 microM) and cholera toxin (100 ng/ml) or the phosphodiesterase inhibitor RO 20-1724 (100 microM). At 48 h, all these treatments had increased beta-endorphin accumulation in the medium and transiently decreased the cellular beta-endorphin content in IL cells, suggesting a parallel effect of cAMP-related drugs on secretion and biosynthesis. Incubating the cells with the Ca++ channel antagonists D600 (50 microM), verapamil (50 microM), and the dihydropyridine nifedipine (0.1 microM) decreased basal POMC mRNA levels, whereas the dihydropyridine BAYK 8644 (0.1 microM), which activates the Ca++ channel, increased POMC mRNA levels after 2 days. In addition, nifedipine decreased the stimulatory effect of forskolin, whereas BAYK 8644 further stimulated the forskolin-increased POMC mRNA levels in IL cells. We conclude that both Ca++ and cAMP may regulate the gene expression of POMC.
Example Output:
Adenosine Cyclic Monophosphate