This paper presents results of a study conducted with undergraduate students involved in either problem-or project-based curricula (Medicine and Engineering, respectively) at the Université de Sherbrooke, Canada. The objective of the present research was to measure the impact of these innovative curricula on students' engagement and persistence in higher education. Our research question was: What determinants better predict students' engagement and persistence in innovative curricula such as PBL? Nine variables were examined as potential predictors of both factors (engagement and persistence). Results showed a variation in variables predicting engagement and persistence, with the most significant predictor being stress related.
The contribution of the carotid body chemoreceptor to postnatal maturation of breathing was evaluated in lambs from 7 to 70 days of age. The study was conducted by comparing the eupneic ventilation and resting pneumograms in intact conscious lambs with those of lambs that were carotid body chemodenervated (CBD) at birth. In comparison to the 1-wk-old intact lambs, the CBD lambs had significant decreases in minute ventilation (VE, 313 vs. 517 ml/kg), tidal volume (VT, 7.2 vs. 10.5 ml/kg), respiratory rate (f, 44 vs. 51 breaths/min), and occlusion pressure (P0.1, 2.8 vs. 7.2 cmH2O). Arterial PO2's were 59 vs. 75 Torr (P less than 0.05) and arterial PCO2's 47 vs. 36 Torr (P less than 0.05), respectively, in CBD and intact lambs. In intact lambs from 7 to 70 days, resting VE decreased progressively from 517 to 274 ml/kg (P less than 0.01) due to a fall in VT, mean inspiratory flow (VT/TI), and f, whereas the ratio of inspiratory time to total breath duration remained constant. P0.1 decreased from 7.2 to 3.9 cmH2O from 7 to 42 days. In contrast the CBD lambs experienced only minimal changes in VE, VT, VT/TI, and f during the same period. VE only decreased from 313 to 218 and P0.1 from 2.8 to 2.4 cmH2O. In contrast to that of intact lambs the resting pneumogram of CBD lambs remained relatively fixed from 7 to 70 days. Three CBD lambs died unexpectedly, without apparent cause, in the 4th and 5th wk of life.(ABSTRACT TRUNCATED AT 250 WORDS)
It has long been claimed that the active expiratory glottic closure observed in newborns, especially during hyaline membrane disease, is related to hypoxia. However, we recently showed that hypoxia does not lead to active expiratory glottic closure in nonsedated lambs. In this study, we test the hypothesis that glottic closure is related to an excess of lung water present at birth. We studied 17 nonsedated lambs after inducing a permeability pulmonary edema via intravenous of either oleic acid (8 lambs) or halothane (9 lambs). We recorded airflow via a facial mask and pneumotachograph, as well as the electromyographic activity (EMG) of the thyroarytenoid muscle (TA), a glottic adductor. Blood gases were measured in 8 lambs via a brachial artery catheter. We identified laryngeal expiratory airflow braking on the breath-by-breath computed flow-volume loop and TA expiratory EMG as evidence of active expiratory glottic adduction. After the injection of oleic acid or halothane, an active expiratory glottic closure was recorded in all lambs but 1, usually throughout the recording period (60 to 300 min). The active expiratory glottic closure was not inhibited after correction of the hypoxia. We conclude that, in nonsedated lambs, a permeability pulmonary edema induces an active expiratory glottic closure. We hypothesize that the expiratory glottic closure commonly observed in newborns could help to ameliorate the alveolocapillary gas exchange by reopening the flooded alveoli.
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