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Soil structure can be defined as the spatial organization of solid mineral and organic particles, and pore space. It is of great importance for soil functioning as it drives ecosystem functions (carbon sequestration, emission of greenhouse gases, nutrient cycling, primary productivity, etc.). Soil structure results from biotic and abiotic factors. Among biotic factors, numerous studies have shown the importance of organic matter, microorganisms, roots and invertebrates. Earthworms are known to play a key role in soil structure formation and maintenance through a continuous production of biogenic structures (casts and burrows). As far as we know, no models describe or quantify the effect of soil invertebrates on soil aggregation and porosity. It is a challenge to describe the physical soil environment for purposes of modelling because a soil is a multi-scale heterogeneous, three-dimensional and dynamic environment. An approach based on fractal theory (often used in soil sciences) was chosen to model such a real complex environment; it was integrated into a multi-agent system (MAS), which allows us to simulate agents (e.g. earthworms) situated in a virtual world (e.g. soil). It is a bottom-up approach that allows us to describe a system at a micro level (e.g. earthworms and their local soil environment) in order to observe, during simulations, macroscopic changes (e.g. soil structure evolution, organic matter dynamics, and microbial functions). In this paper we describe the SWORM (for ‘Simulated Worms’) model and the simulator, and present the results of the simulation applied to a case study. The effect of compacting and decompacting earthworm species on the structure of humid savanna soil at Lamto in Côte d’Ivoire has been widely studied. Quantitative and graphical outputs (e.g. thin sections of the virtual soil) indicate that the simulator was able to reproduce the effects of both compacting and decompacting species. Different ways to improve the model are discussed. [ABSTRACT FROM AUTHOR]

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Amiodarone can induce severe hyperthyroidism that justifies its withdrawal and initiation of antithyroid drugs. Impossibility to stop amiodarone, failure to control hyperthyroidism and unfavourable evolution can lead to thyroidectomy. Cardiac manifestations, persistence of hyperthyroidism and interactions between amiodarone and anaesthetic or haemodynamic drugs may contraindicate anaesthesia. We report nine consecutive cases of amiodarone-associated hyperthyroidism that prompted us to perform thyroidectomy under general anaesthesia. The features and anaesthetic data of patients were noted. The antithyroid medical treatment failed in all patients. After thyroidectomy, evolution was favourable in all nine cases, without any intra or postoperative complication, in spite of the extent of hyperthyroidism and the severity of the associated cardiac problems. Despite potential high risks, thyroidectomy for amiodarone-induced hyperthyroidism does not seem to increase morbidity or mortality and allows a quick return to euthyroidism and reintroduction of amiodarone. [Copyright &y& Elsevier]

The L-type Ca2+ current (ICa-L) plays a key role in the cardiac excitation-contraction (E-C) coupling. Thus, it is a major target for many transmitters and hormones modulating cardiac function and, therefore, for pharmacological drugs to regulate inotropy. Ca2+ (and other) ion currents are commonly studied in animal tissues for practical reasons. Investigations in human cardiomyocytes started extensively only ten years ago with the development of patch-clamp techniques, enzymatic cell dissociation procedures, and surgical techniques. These studies have already provided valuable information concerning the nature, biophysics, pharmacology and regulation of human cardiac ionic currents in normal and diseased tissues. Interesting advances have been made to understand the role of ICa-L in the development of chronic atrial fibrillation (AF). Alterations of single channel activity and regulation of macroscopic ICa-L have also been found in heart failure (HF), although some of the data are divergent and puzzling. The T-type Ca2+ current (ICa-T) has never been recorded in human cardiomyocytes. After a rapid overview of the basic properties of human cardiac Ca2+ currents, we focus on selected aspects of pathophysiology that are still unsolved. [ABSTRACT FROM AUTHOR]

Nous distinguons trois visions de la complexité afin de clarifier les contours de la recherche dans ce domaine. Nous utilisons le démon de Laplace comme référence pour présenter ces visions. La vision 1 brise le rêve du démon de Laplace en identifiant des systèmes particuliers qui lui résistent en mathématiques, physique et informatique. La vision 2 propose une nouvelle version du rêve de Laplace fondée sur la disponibilité récente de grandes quantités de données et de nouvelles technologies de programmation, de stockage et de calcul. La vision 3 met le démon face au défi de simuler la subjectivité et ses effets collectifs.

The most debated status of the wave function of Quantum Mechanics is discussed in the light of the epistemological vs ontological opposition. [ABSTRACT FROM AUTHOR]