Competitive dynamics of two erosion patterns around a cylinder

We investigate experimentally the local erosion of a granular bed near a fixed vertical cylinder that emerges from the bed. The onset of erosion arising at the base of the cylinder and usually ascribed to the wrapping horseshoe vortex is determined and rationalized by a flow contraction effect. We report a new erosion pattern visible downstream of the cylinder that consists of two side-by-side elongated holes. This pattern is observed for flow regimes close to the horseshoe scour onset, whose growth usually inhibits its spatiotemporal development.Comment: 6 pages, 6 figure

Experimental investigation of tsunami waves generated by granular collapse into water

The generation of a tsunami wave by an aerial landslide is investigated through model laboratory experiments. We examine the collapse of an initially dry column of grains into a shallow water layer and the subsequent generation of waves. The experiments show that the collective entry of the granular material into water governs the wave generation process. We observe that the amplitude of the wave relative to the water height scales linearly with the Froude number based on the horizontal velocity of the moving granular front relative to the wave velocity. For all the different parameters considered here, the aspect ratio and the volume of the column, the diameter and density of the grains, and the height of the water, the granular collapse acts like a moving piston displacing the water. We also highlight that the density of the falling grains has a negligible influence on the wave amplitude, which suggests that the volume of grains entering the water is the relevant parameter in the wave generation.Comment: 23 pages, 16 figure

Otolith microstructure analysis with OTC validation confirms age overestimation in Atlantic thread herring Opisthonema oglinum from north-eastern Brazil

The daily periodicity of micro-increments in the otoliths of Atlantic thread herring Opisthonema oglinum was demonstrated from juveniles injected with oxytetracycline and reared for up to 62 days. Micro-increments ranged from 26 to 358 in the overall sample. Von Bertalanffy growth function (VBGF) using micro-increment counts were: L-infinity = 337 mm fork length (L-F) (s.e. = 31 mm); K = 1.2 (s.e. = 0.2) and t(0) = 0.04 years (s.e. = 0.01 years). The otolith-based growth was corroborated using the L-F frequency analysis. Observed lengths of increments were considered unsuitable for VBGF derivation, as no increase in size was obtained from them. Furthermore, the high percentage of unreadable otoliths suggests that increment analysis is unreliable for age estimation. Most growth occurs within the first year, differing from previous longevity estimates of 4-8 years. In contrast with published information, O. oglinum is a fast-growing and short-lived species

Competitive dynamics of two erosion patterns around a cylinder

We investigate experimentally the local erosion of a granular bed near a fixed vertical cylinder that emerges from the bed. The onset of erosion arising at the base of the cylinder and usually ascribed to the wrapping horseshoe vortex is determined and rationalized by a flow contraction effect. We report a new erosion pattern visible downstream of the cylinder that consists of two side-by-side elongated holes. This pattern is observed for flow regimes close to the horseshoe scour onset, whose growth usually inhibits its spatiotemporal development

Rural Development and Food diversity in France

In France today, there can be no rural development without food diversity, just as there is no food diversity without rural development. Food diversity through rural development is best illustrated by labels of quality and origin. In this way, we can see that food diversity is promoted by policies for rural development. Nonetheless, food diversity is sometimes hindered by rural development policy. A good example would be regulations concerning seed and seedlings, which can only be marketed after registration in the official catalogue. However, the criteria for registration exclude de facto certain types of seed, particularly those from seed saving practices, which leads to a decrease in food diversity. On closer examination, rural development promotes food diversity as much as it hinders it. In contrast, food diversity helps foster rural development. Producers try to both consolidate structurally and to become involved in every step of the marketing of their produce. Their aim is quite simple: to remove distribution intermediaries as much as possible by developing closer links to the end consume

Rural development and food diversity in France

In France today, there can be no rural development without food diversity, just as there is no food diversity without rural development. Food diversity through rural development is best illustrated by labels of quality and origin. In this way, we can see that food diversity is promoted by policies for rural development. Nonetheless, food diversity is sometimes hindered by rural development policy. A good example would be regulations concerning seed and seedlings, which can only be marketed after registration in the official catalogue. However, the criteria for registration exclude de facto certain types of seed, particularly those from seed saving practices, which leads to a decrease in food diversity. On closer examination, rural development promotes food diversity as much as it hinders it. In contrast, food diversity helps foster rural development. Producers try to both consolidate structurally and to become involved in every step of the marketing of their produce. Their aim is quite simple: to remove distribution intermediaries as much as possible by developing closer links to the end consume

Croissance du zircaloy 4 sous flux neutronique

Available from CEN Saclay, Service de Documentation, 91191 Gif-sur-Yvette Cedex (France) / INIST-CNRS - Institut de l'Information Scientifique et TechniqueSIGLEFRFranc