The fundamental group of an algebraic link

We compute the fundamental group of an algebraic link. To cite this article: O. Neto, P.C. Silva, C. R. Acad. Sci. Paris, Ser. I 340 (2005).     

A better understanding of the background of CR-39 detectors

The background of CR-39 detectors varies from batch to batch, from foil to foil in the same batch, from one side to another of the same foil and within the same foil surface. In spite of many efforts made in the past, little success has been achieved in producing detectors with a consistently low background. For this reason, new investigations have been undertaken with the specific scope in mind to improve the background of these detectors. The key strategy of these studies was to investigate whether the background tracks originate from the detector surface or from detector bulk, if not from both. From these systematic investigations it was possible to demonstrate that most of the background is due to defects present on the detector surface. For this reason, the simplest way to reduce the background is to carry out a heavy pre-etching prior to the use of the CR-39 detector. This procedure has been successfully exploited not only to increase the signal-to-noise ratio of CR-39-based radon dosimeters but also to carry out different radon measurements with the same CR-39 foil.     

On the numerical relaxation of single-slip plasticity in finite strains

The modeling of the elastoplastic behaviour of single crystals with infinite latent hardening leads to a nonconvex energy density, whose minimization produces fine structures. The computation of the quasiconvex envelope of the energy density is faced in this case with huge numerical difficulties caused by the clusters of local minima. By exploiting the structure of the problem, we present a fast and efficient numerical relaxation algorithm as alternative to global optimization techniques usually adopted in literature which are computationally more expensive. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Non-passive Transport of Volatile Organic Compounds Infiltrated from a Surface Disk Source

An unsaturated flow and non-passive transport model for water-soluble organic compounds has been implemented in cylindrical coordinates, with a top boundary condition that accounts for different zones of the surface that can be under infiltration or volatilization independently. We simulated two-dimensional infiltration of aqueous mixtures of methanol from a disk source, its redistribution and volatilization in both homogeneous and heterogeneous soils. Simulations showed that the incoming composition significantly affects volumetric liquid content and concentration profiles, as well as the fraction of infiltrated mass of methanol that is released to the atmosphere. Concentration-dependent viscosity had the major impact on the liquid flow. The differences in volumetric liquid content and normalized concentration of methanol became more pronounced during transport through a soil composed of a clay lens embedded within a main matrix of sandy clay loam texture. Dispersion in the liquid-phase was the predominant transport mechanism when dispersivity at saturation was set to 7.8 cm. However, for dispersivity of 1.0 cm, changes in composition led to changes in surface tension inducing significantly higher liquid flow. In this case, liquid-phase advection was the most active transport mechanism for homogeneous soils and highly concentrated infiltrating mixtures.     

Further experimental evidence on the importance of tertiary effects in the evolution of pyramids on bombarded copper

Further experimental results relating to the role of tertiary effects in the evolution of pyramids on bombarded Cu surfaces are presented. The observed enlargement of the apex angles during the shrinking process, together with the previously described mushroom-like structures, are taken as evidence for the existence of these effects.