Barchans are crescent-shaped dunes commonly found in diverse environments and scales: from the 10-cm-long barchans under water to 1-km-long on Mars, passing by 100-m-long Earth's deserts. Although ubiquitous nature, there is a lack of grain-scale computations growth evolution those bedforms. In this paper, we investigate values grain properties (coefficients sliding friction, rolling friction r...

     This research has attempted to measure the parameters of barchan dunes as one of the desert landforms. This has been conducted by a field survey using cartographic techniques. In the field, two barchan dunes have completely been surveyed by total station equipment. Using the sample points a novel method has been devised to measure the barchans parameters. The method is mainly based on geom...

Barchans are dunes of high mobility which have a crescent shape and propagate under conditions of unidirectional wind. However, sand dunes only appear above a critical size, which scales with the saturation distance of the sand flux [P. Hersen, S. Douady, and B. Andreotti, Phys. Rev. Lett. 89, 264301 (2002); B. Andreotti, P. Claudin, and S. Douady, Eur. Phys. J. B 28, 321 (2002); G. Sauermann, ...

Two-dimensional gas chromatography (GC×GC) plays a central role into the elucidation of complex samples. The automation of the identification of peak areas is of prime interest to obtain a fast and repeatable analysis of chromatograms. To determine the concentration of compounds or pseudo-compounds, templates of blobs are defined and superimposed on a reference chromatogram. The templates then ...

This study represents the first characterization of sand microbiota in migrating barchan sand dunes. Bacterial communities were studied through direct counts and cultivation, as well as 16S rRNA gene and metagenomic sequence analysis to gain an understanding of microbial abundance, diversity, and potential metabolic capabilities. Direct on-grain cell counts gave an average of 5.3 ± 0.4 x 105 ce...