Proposal for a method for analysing smart personal protective systems.

The emergence of 'smart' or 'intelligent' personal protective systems (SPPS) raises new questions with regard to occupational risk prevention. While manufacturers and standardization bodies are wondering about the safety requirements applicable when designing or assessing such equipment, the user companies wonder about the performance and the limits of such equipment and the risks associated with its use. This article first gives a definition for SPPS in order to clarify the exchanges between the stakeholders. It then proposes a four-stage approach to deal with the concepts of systems and intelligence applied to personal protective equipment. For the 'smart' parts, it is proposed, by analogy with the field of 'machinery', to define a safety level for the 'smart' parts which participate in the individual protection functions. In order to show its applicability, this approach is then applied to four examples of SPPS.

Experimental evaluation of an efflux-influx model of C exudation by individual apical root segments.

The aim of this study was to evaluate if a model describing the efflux and the influx of C through the root surface could be fitted to experimental short-term kinetics of carbon (C) exudation by individual apical root segments in maize (Zea mays L.). The efflux of C was set constant or modelled by a power function of the distance from the apex to simulate the greater release of C around the root tip commonly reported in the literature. The influx was proportional to the C concentration in the external solution to simulate the active re-uptake of exudates by the root. Plants were exposed to full light or to shade to manipulate C allocation to roots. The model with a constant efflux gave satisfactory fits to the kinetics of exudation (average R(2)=0.66). The average gross efflux was then 2.1 mug C cm(-2) root surface h(-1). The model was improved if exudation was set more intense towards the root apex (average R(2)=0.74). The estimated gross efflux decreased then from 5.2 mug C cm(-2) h(-1) at the apex to 1.8 mug C cm(-2) h(-1) for the region located 5-25 cm from the root tip. The decrease in net exudation of individual roots due to the shading of plants was weak, which may indicate that the import of C by the primary roots studied was not reduced significantly. By describing the exudation of an apical root segment of variable length and diameter, the model is a first step in linking exudation to root system architecture models and to whole plant functioning.