"Contemplating the next maneuver": functional neuroimaging reveals intraoperative decision-making strategies

OBJECTIVE: To investigate differences in the quality, confidence, and consistency of intraoperative surgical decision making (DM) and using functional neuroimaging expose decision systems that operators use. SUMMARY BACKGROUND DATA: Novices are hypothesized to use conscious analysis (effortful DM) leading to activation across the dorsolateral prefrontal cortex, whereas experts are expected to use unconscious automation (habitual DM) in which decisions are recognition-primed and prefrontal cortex independent. METHODS: A total of 22 subjects (10 medical student novices, 7 residents, and 5 attendings) reviewed simulated laparoscopic cholecystectomy videos, determined the next safest operative maneuver upon video termination (10 s), and reported decision confidence. Video paradigms either declared ("primed") or withheld ("unprimed") the next operative maneuver. Simultaneously, changes in cortical oxygenated hemoglobin and deoxygenated hemoglobin inferring prefrontal activation were recorded using Optical Topography. Decision confidence, consistency (primed vs unprimed), and quality (script concordance) were assessed. RESULTS: Attendings and residents were significantly more certain (P < 0.001), and decision quality was superior (script concordance: attendings = 90%, residents = 78.3%, and novices = 53.3%). Decision consistency was significantly superior in experts (P < 0.001) and residents (P < 0.05) than novices (P = 0.183). During unprimed DM, novices showed significant activation of the dorsolateral prefrontal cortex, whereas this activation pattern was not observed among residents and attendings. During primed DM, significant activation was not observed in any group. CONCLUSIONS: Expert DM is characterized by improved quality, consistency, and confidence. The findings imply attendings use a habitual decision system, whereas novices use an effortful approach under uncertainty. In the presence of operative cues (primes), novices disengage the prefrontal cortex and seem to accept the observed operative decision as correct

Study of physical and mechanical applications on ceramics of the lateritic and alluvial clayey mixtures of the Yaoundé region (Cameroon)

International audienceCeramic products were prepared by mixing lateritic and alluvial clayey materials of Yaoundé (Cameroon) in the humid tropical region, with 20, 50 and 80 wt.% of alluvial clay respectively in lateritic clay. Samples were grounded and sieved and powders obtained were shaped by uniaxial pressing of wet granules and fired under low temperatures between 350 and 1050 °C. Open porosity, bulk density and flexural strength were the principal properties characterised. Results indicates that a maximum of 80 wt.% of alluvial clayey material must be added to lateritic clays of Yaoundé, to obtain weakly porous ceramics and to attain the bulk density ranging from 1.56 to 1.97 g/m3 and a flexural strength of 6–19.85 MPa would be equivalent alluvial clay ceramics. But ceramics with lesser amount of alluvial clayey materials also have interesting flexural strengths in the range of 5–16 MPa, thus higher than porous lateritic clay ceramics