Safety culture as a rational myth: why developing safety culture implies engineering resilience?

Available on: http://www.resilience-engineering.org/REPapers/Chevreau_R.pdfInternational audienceWork on resilience engineering has stimulated an ever growing interest illustrated by the increasing number of publications on the subject. While at the same time, the older notion of safety culture continues to interest scientists and practitioners. The purpose of this article is to build a managerial approach of safety culture which takes in resilience engineering. It first describes the epistemological background of this approach based on intervention-research. This aims at introducing the notion of "rational myth" that describes the principles on which organized action bases itself at a given time. Secondly, the article identifies and presents three managerial principles on which risk mastering is centered: the principle of responsibility, the principle of anticipation and the principle of resilience. It then shows that the notion of safety culture as historically defined after the Chernobyl disaster and taken into account by managers can be analyzed as a rational myth for risk mastering including these three principles. It illustrates this by an example taken from an intervention led in partnership with the French pharmaceutical company Sanofi-Aventis. The article finally concludes that developing safety culture is more adapted to risk mastering principles than engineering resilience

Biopsym : a learning environment for transrectal ultrasound guided prostate biopsies

This paper describes a learning environment for image-guided prostate biopsies in cancer diagnosis; it is based on an ultrasound probe simulator virtually exploring real datasets obtained from patients. The aim is to make the training of young physicians easier and faster with a tool that combines lectures, biopsy simulations and recommended exercises to master this medical gesture. It will particularly help acquiring the three-dimensional representation of the prostate needed for practicing biopsy sequences. The simulator uses a haptic feedback to compute the position of the virtual probe from three-dimensional (3D) ultrasound recorded data. This paper presents the current version of this learning environment

BiopSym: a simulator for enhanced learning of ultrasound-guided prostate biopsy

This paper describes a simulator of ultrasound-guided prostate biopsies for cancer diagnosis. When performing biopsy series, the clinician has to move the ultrasound probe and to mentally integrate the real-time bi-dimensional images into a three-dimensional (3D) representation of the anatomical environment. Such a 3D representation is necessary to sample regularly the prostate in order to maximize the probability of detecting a cancer if any. To make the training of young physicians easier and faster we developed a simulator that combines images computed from three-dimensional ultrasound recorded data to haptic feedback. The paper presents the first version of this simulator

Expression of a bacterial effector, harpin N, causes increased resistance to fire blight in Pyrus communis

The rapid and effective activation of disease resistance responses is essential for plant defense against pathogen attack. These responses are initiated when pathogen-derived molecules (elicitors) are recognized by the host. In order to create novel mechanisms for fire blight resistance in pear, we have generated transgenic pears expressing the elicitor harpin Nea from Erwinia amylovora under the control of the constitutive promoter CaMV35S. The transient expression of hrpN Ea in pear cells did not provoke any apparent damage. Therefore, stable constitutive expression of hrpN Ea was studied in seventeen transgenic clones of the very susceptible cultivar "Passe Crassane.” Most transgenic clones displayed significant reduction of susceptibility to fire blight in vitro when inoculated by E. amylovora, which was positively correlated to their degree of expression of the transgene hrpN Ea . These results indicate that ectopic expression of a bacterial elicitor such as harpin Nea is a promising way to improve pear resistance to fire bligh

Adsorption of propane, propylene and isobutane on a metal–organic framework : molecular simulation and experiment

The separation of propane/propylene mixtures is the most energy-intensive operation practiced in the petrochemical industry. Adsorptive processes are currently viewed as a promising alternative to cryogenic distillation for the separation of these mixtures. In this paper, we explore the possibility of using a new metal-organic framework material, CuBTC, in adsorptive separation processes, particularly in a simulated moving bed (SMB) context using isobutane as a potential desorbent. A gravimetric method has been used to measure the adsorption equilibrium isotherms of propylene, propane and isobutane onto a commercial CuBTC powder over a temperature range from 323 to 423K and pressures up to 100kPa. These were complemented by a detailed experimental characterization of the structure of CuBTC using XRD and SEM techniques. Comparison of experimental isotherms with grand canonical Monte Carlo simulations in CuBTC showed that propane adsorption occurs preferentially in small octahedral pockets, while isobutame is excluded from these pockets due to its bulky structure. Propylene was seen to interact strongly with unsaturated metal sites, due to specific pi-Cu bonds. These interactions significantly enhance the affinity of this MOF for unsaturated hydrocarbons. Furthermore, in a range of temperatures and pressures, the affinity of CuBTC for isobutane is intermediate to that of propane and propylene. Our results suggest that CuBTC-isobutane is a very promising adsorbent-desorbent pair for use in SMB processes for propane/propylene separations

Reverse shape selectivity in the adsorption of hexane and xylene isomers in MOF UiO-66

An adsorption study of hexane and xylene isomers mixtures was addressed in a rigid zirconium terephthalate UiO-66 (UiO for University of Oslo) with octahedral and tetrahedral cavities of free diameter close to 1.1 nm and 0.8 nm, respectively. Multicomponent equimolar breakthrough experiments show that the adsorption hierarchy of structural isomers in UiO-66 is opposite to the one observed in conventional adsorbents. For hexane isomers, it was found that the amount adsorbed increases with the degree of branching, being 2,2-dimethylbutane (22DMB) and 2,3-dimethylbutane (23DMB) the more retained molecules. Regarding the xylene isomers, the results show that the adsorption of the bulkier ortho-xylene(oX) is favoured compared to its homologues. The structural similarity between MOF UiO-66 and zeolite MCM-22 suggests that the reverse shape selectivity observed in the adsorption of hexane and xylene isomers might be attributed to the rotational freedom of the molecules inside the small cavities

New formulation of mechanical specific energy (MSE) taking into account the hydraulic effects for PDC bits

In today’s unstable economic environment, the cost of drilling continues to be the most important limitation factor to drill new wells. Thus, to reach the deepest depth at the lowest price, drilling needs to be optimized. To do so, drillers monitor two values: the rate of penetration (ROP) and the mechanical specific energy (MSE). However, MSE has been proven to be more valuable because it links ROP with drilling parameters as weight on bit (WOB) or torque. Moreover, it allows computation of mechanical efficiency (EFFM), which is directly linked to the drilling efficiency. The latest MSE formulations only consist of three components: a thrust one, a rotary one and a hydraulic one, which only represents the action of the jet impacts. The associated mechanical efficiency consists of the minimum MSE (MSEmin) divided by the actual MSE. This formulation has been proven to be inaccurate by several authors. In fact, they showed that as hydrostatic pressure increases, the mechanical efficiency decreases. This decrease has been explained by these authors by the fact that some important hydraulic phenomena are not considered. These phenomena are the shear dilatancy and change in failure mechanism. Shear dilatancy is the phenomenon that happens when the drill bit shears the rock: the rock dilates which causes a decrease in pore pressure and thus an increase in differential pressure which strengthens the rock. This strengthening has been quantified and MSE has been reformulated to take into account this phenomenon. At atmospheric conditions, the failure mechanism is usually brittle, creating chip like cutting. However, when applying hydrostatic pressure this failure mode switches towards the ductile mode creating ribbon like cutting. The formulation of the MSEmin has been adapted to take into consideration this phenomenon. In order to help an engineer to take into account these phenomena, a program was developed that shows graphically and quantitatively the influence of these mechanisms. The program allows the user to vary several parameters and is capable of extracting drilling data from an existing Excel sheet. This is important since the influence of these mechanisms can create differences of around 10% between the efficiencies calculated with and without considering these phenomena, and this difference can reach values over 20% in certain formationsPetroleum and Geosystems Engineerin