Experimental study of the compaction dynamics for 2D anisotropic granular materials

We present an experimental study of the compaction dynamics for two-dimensional anisotropic granular systems. Compaction dynamics is measured at three different scales : (i) the macroscopic scale through the packing fraction $\rho$, (ii) the mesoscopic scale through both fractions of aligned grains $\phi_{a}$ and ideally ordered grains $\phi_{io}$, and (iii) the microscopic scale through both rotational and translational grain mobilities $\mu_{r,t}$. The effect of the grain rotations on the compaction dynamics has been measured. At the macroscopic scale, we have observed a discontinuity in the late stages of the compaction curve. At the mesoscopic scale, we have observed the formation and the growth of domains made of aligned grains. From a microscopic point of view, measurements reveal that the beginning of the compaction process is essentially related to translational motion of the grains. The grains rotations drive mainly the process during the latest stages of compaction.Comment: 8pages, 11 figure

Ripple and kink dynamics

We propose a relevant modification of the Nishimori-Ouchi model [{\em Phys. Rev. Lett.} {\bf 71}, 197 (1993)] for granular landscape erosion. We explicitly introduce a new parameter: the angle of repose $\theta_r$, and a new process: avalanches. We show that the $\theta_r$ parameter leads to an asymmetry of the ripples, as observed in natural patterns. The temporal evolution of the maximum ripple height $h_{max}$ is limited and not linear, according to recent observations. The ripple symmetry and the kink dynamics are studied and discussed.Comment: 7 pages, 10 figure, RevTe

Identification of tenuis of four French Polynesian <i>Carapini</i> (Carapidae: Teleostei)

Four species of adult Carapini (Carapidae) occur on Polynesian coral reefs: Encheliophis gracilis, Carapus boraborensis, C. homei and C. mourlani. Samples collected in Rangiroa and Moorea allowed us to obtain different tenuis (larvae) during their settlement phases or directly inside their hosts. These were separated into four lots on the basis of a combination of pigmentation, meristic, morphological, dental and otolith (sagittae) features. Comparison of these characters with those of the adults allows, for the first time, taxonomic identification of these tenuis-stage larvae

Scaling in the Bombay Stock Exchange Index

In this paper we study BSE Index financial time series for fractal and multifractal behaviour. We show that Bombay stock Exchange (BSE)Index time series is mono-fractal and can be represented by a fractional Brownian motion.Comment: 11 pages,3 figure

Dimer percolation and jamming on simple cubic lattice

We consider site percolation of dimers (``neadles'') on simple cubic lattice. The percolation threshold is estimated as $p_c^\text{perc} \approx 0.2555 \pm 0.0001$. The jamming threshold is estimated as $p_c^\text{jamm} = 0.799 \pm 0.002$.Comment: 3 pages, 4 figures, submitted to EPJ

Intraocular Pressure Correlates with Optic Nerve Sheath Diameter in Patients with Normal Tension Glaucoma

PURPOSE: 1. Identify differences in optic nerve sheath diameter (ONSD) as an indirect measure of intracranial pressure (ICP) in glaucoma patients and a healthy population. 2. Identify variables that may correlate with ONSD in primary open-angle glaucoma (POAG) and normal tension glaucoma (NTG) patients. METHODS: Patients with NTG (n = 46) and POAG (n = 61), and healthy controls (n = 42) underwent B-scan ultrasound measurement of ONSD by an observer masked to the patient diagnosis. Intraocular pressure (IOP) was measured in all groups, with additional central corneal thickness (CCT) and visual field defect measurements in glaucomatous patients. Only one eye per patient was selected. Kruskal-Wallis or Mann-Whitney were used to compare the different variables between the diagnostic groups. Spearman correlations were used to explore relationships among these variables. RESULTS: ONSD was not significantly different between healthy, NTG and POAG patients (6.09 ± 0.78, 6.03 ± 0.69, and 5.71 ± 0.83 respectively; p = 0.08). Visual field damage and CCT were not correlated with ONSD in either of the glaucoma groups (POAG, p = 0.31 and 0.44; NTG, p = 0.48 and 0.90 respectively). However, ONSD did correlate with IOP in NTG patients (r = 0.53, p  0.25 in all groups). CONCLUSIONS: Indirect measurements of ICP by ultrasound assessment of the ONSD may provide further insights into the retrolaminar pressure component in glaucoma. The correlation of ONSD with IOP solely in NTG patients suggests that the translaminar pressure gradient may be of particular importance in this type of glaucoma

Tailles de première maturité et de capture de six espèces de poisson-chat dans le delta de l’Ouémé au Bénin (Afrique de l’Ouest)

Dans le moyen delta de l&rsquo;Ou&eacute;m&eacute; au B&eacute;nin, les tailles de premi&egrave;re maturit&eacute; et de capture des populations de six esp&egrave;ces de poisson-chat ont &eacute;t&eacute; &eacute;tudi&eacute;es. Il s&rsquo;agit de Clarias gariepinus, de C. ebriensis, de Schilbe intermedius, de S. mystus, de Synodontis schall et de S. nigrita. La relation de type sigmo&iuml;de entre le pourcentage de maturit&eacute; sexuelle (P) et la taille (Lt) des poissons a &eacute;t&eacute; d&eacute;termin&eacute;e d&rsquo;apr&egrave;s le mod&egrave;le logistique de Dagnelie (1973). L&rsquo;&eacute;quation g&eacute;n&eacute;rale de Von Bertalanffy (1938) incorpor&eacute;e au logiciel FISAT II a permis de d&eacute;terminer les tailles de premi&egrave;re capture (Lc50). En g&eacute;n&eacute;ral, les m&acirc;les maturent &agrave; une taille inf&eacute;rieure &agrave; celle des femelles. Les tailles &agrave; la premi&egrave;re maturit&eacute; (L50) sont sup&eacute;rieures aux tailles de premi&egrave;re capture (Lc50). On en d&eacute;duit une surexploitation des six populations de poissons &eacute;tudi&eacute;es qui sont en g&eacute;n&eacute;ral p&ecirc;ch&eacute;es avant la premi&egrave;re reproduction. Il serait int&eacute;ressant que les poissons soient captur&eacute;s &agrave; une plus grande taille (Lc50 &gt; L50)Keywords: Poissons-chats, maturit&eacute; sexuelle, exploitation, delta de l&rsquo;Ou&eacute;m&eacute