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Context Tropical soils have complex hydromechanical behaviour compared to ordinary soils and are often found in regions with well-defined wet and dry seasons. The analysis of the interaction between the soil and the atmosphere comprises understanding of multiple phenomena, such as infiltration and runoff. Unfortunately, the dynamics of soil–atmosphere interaction are commonly modelled at the watershed scale, using average parameters that do not allow an in depth understanding of the soil–water phenomena involved. Aims This paper presents an investigation of the soil–atmosphere interaction at the local scale, using numerical and physical modelling of the infiltration and runoff of an exposed tropical soil in a laboratory rainfall simulator. Methods The effect of rainfall with two different intensities of 86.0 and 200.0mmh−1 was used to physically and numerically evaluate infiltration parameters, runoff, volumetric water content, and degree of saturation at five locations in the soil specimen. Key results Calibration of the numerical model showed a maximum root-mean-square error of 0.17. In addition, the modelling exercises indicated the need for an equilibrium time of 48h for the sample studied under the imposed conditions. Conclusions Results of numerical simulation showed that the representation of the physical model by the numerical model was satisfactory and promising. Thus, the numerical model showed applicability for validating the boundary conditions of physical tests using rainfall simulators.

Integrins are cellular adhesion receptors that mediate signaling and play key roles in the development of multicellular organisms. However, their role in the cellular events leading to myotome formation is completely unknown. Here, we describe the expression patterns of the α1, α4, α5, α6, and α7 integrin subunits in the mouse myotome and correlate them with the expression of several differentiation markers. Our results indicate that these integrin subunits may be differentially involved in the various phases of myogenic determination and differentiation. A detailed characterization of the myogenic cell types expressing the α4 and α6 subunits showed a regionalization of the myotome and dermomyotome based on cell‐adhesion properties. We conclude that α6β1 may be an early marker of epaxial myogenic progenitor cells. In contrast, α4β1 is up‐regulated in the intercalated myotome after myocyte differentiation. Furthermore, α4β1 is expressed in the hypaxial dermomyotome and is maintained by early hypaxial myogenic progenitor cells colonizing the myotome. Developmental Dynamics 231:402–415, 2004. © 2004 Wiley‐Liss, Inc.