Une économie de la coordination : les ressources de la corporation

NoteÀ la crise de la performance industrielle des années 70/80 a correspondu également une crise des modèles productifs. La relation analogique des modèles au réel, par sa stylisation pour l'économiste ou par création d'ideaux-types pour le sociologue, était mis en défaut. A partir d'une approche analytique interdisciplinaire (gestion, sociologie du travail et sociologie des relations professionnelles), il s'agit ici d'examiner les conditions théoriques d'une approche qui permettent de rendre compte de manière continue — c'est-à-dire sans changer de registre de démonstration en fonction des instances étudiées — des dynamiques productives dans les organisations industrielles et marchandes

Behavioural Adjustment in Response to Increased Predation Risk: A Study in Three Duck Species

Predation directly triggers behavioural decisions designed to increase immediate survival. However, these behavioural modifications can have long term costs. There is therefore a trade-off between antipredator behaviours and other activities. This trade-off is generally considered between vigilance and only one other behaviour, thus neglecting potential compensations. In this study, we considered the effect of an increase in predation risk on the diurnal time-budget of three captive duck species during the wintering period. We artificially increased predation risk by disturbing two groups of 14 mallard and teals at different frequencies, and one group of 14 tufted ducks with a radio-controlled stressor. We recorded foraging, vigilance, preening and sleeping durations the week before, during and after disturbance sessions. Disturbed groups were compared to an undisturbed control group. We showed that in all three species, the increase in predation risk resulted in a decrease in foraging and preening and led to an increase in sleeping. It is worth noting that contrary to common observations, vigilance did not increase. However, ducks are known to be vigilant while sleeping. This complex behavioural adjustment therefore seems to be optimal as it may allow ducks to reduce their predation risk. Our results highlight the fact that it is necessary to encompass the whole individual time-budget when studying behavioural modifications under predation risk. Finally, we propose that studies of behavioural time-budget changes under predation risk should be included in the more general framework of the starvation-predation risk trade-off

Selectivity of C-H activation and competition between C-H and C-F bond activation at fluorocarbons

Partially fluorinated alkanes, arenes and alkenes can be transformed by a variety of transition metal and lanthanide systems. Although the C-H bond is weaker than the C-F bond regardless of the hybridization of the carbon, the reaction of the C-F bond at the metal is usually more exothermic than the corresponding reaction of the C-H bonds. Both bonds are activated by the metal systems, but the preference for activating these bonds depends on the nature of the hydrocarbon and of the metal system, so that the reaction can be directed exclusively toward C-H or C-F bonds or yield a mixture of products. Additionally, the presence of fluorine differentiates between C-H bonds at different positions resulting in regioselective C-H bond activation; paradoxically, the strongest C-H bond reacts preferentially. The purpose of this review is to describe the field of reaction of partially fluorinated substrates with transition metal atoms, ions and molecular complexes. The controlling physical properties (thermodynamics and kinetics) are described first, followed by a description of stoichiometric reactions, with the competition between the C-H and C-F activations as focus. A few representative catalytic systems are discussed. The review also highlights the benefit of combining experimental and theoretical studie

Does taking endurance into account improve the prediction of weaning outcome in mechanically ventilated children?

INTRODUCTION: We conducted the present study to determine whether a combination of the mechanical ventilation weaning predictors proposed by the collective Task Force of the American College of Chest Physicians (TF) and weaning endurance indices enhance prediction of weaning success. METHOD: Conducted in a tertiary paediatric intensive care unit at a university hospital, this prospective study included 54 children receiving mechanical ventilation (≥6 hours) who underwent 57 episodes of weaning. We calculated the indices proposed by the TF (spontaneous respiratory rate, paediatric rapid shallow breathing, rapid shallow breathing occlusion pressure [ROP] and maximal inspiratory pressure during an occlusion test [Pi(max)]) and weaning endurance indices (pressure-time index, tension-time index obtained from P(0.1 )[TTI(1)] and from airway pressure [TTI(2)]) during spontaneous breathing. Performances of each TF index and combinations of them were calculated, and the best single index and combination were identified. Weaning endurance parameters (TTI(1 )and TTI(2)) were calculated and the best index was determined using a logistic regression model. Regression coefficients were estimated using the maximum likelihood ratio (LR) method. Hosmer–Lemeshow test was used to estimate goodness-of-fit of the model. An equation was constructed to predict weaning success. Finally, we calculated the performances of combinations of best TF indices and best endurance index. RESULTS: The best single TF index was ROP, the best TF combination was represented by the expression (0.66 × ROP) + (0.34 × Pi(max)), and the best endurance index was the TTI(2), although their performance was poor. The best model resulting from the combination of these indices was defined by the following expression: (0.6 × ROP) – (0.1 × Pi(max)) + (0.5 × TTI(2)). This integrated index was a good weaning predictor (P < 0.01), with a LR(+ )of 6.4 and LR(+)/LR(- )ratio of 12.5. However, at a threshold value <1.3 it was only predictive of weaning success (LR(- )= 0.5). CONCLUSION: The proposed combined index, incorporating endurance, was of modest value in predicting weaning outcome. This is the first report of the value of endurance parameters in predicting weaning success in children. Currently, clinical judgement associated with spontaneous breathing trials apparently remain superior