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Artificial Channel (artificial + channel)

Distribution by Scientific Domains
Life Sciences50%

Selected Abstracts

Illumination influences the ability of migrating juvenile salmonids to pass a submerged experimental weir

ECOLOGY OF FRESHWATER FISH, Issue 2 2009
P. S. Kemp
Abstract,,, The downstream migration of juvenile salmonids has previously been considered predominantly passive. It has been argued that passive displacement during periods of darkness is, partially at least, a result of an inability to maintain a fixed position in the absence of visual cues. In this study, behaviour of juvenile Pacific salmonids was assessed under conditions of light and dark as they passed through an artificial channel and encountered a submerged weir. Results indicated that when light, fish formed schools and actively explored the channel. Conversely, when dark (infrared illumination only) they did not form schools, but maintained randomly distributed positions holding station against the flow. As a consequence, more fish approached and either passed, or rejected, the weir when light. The majority of fish that passed the weir did so within the first minute of each trial. Fish predominantly passed through the channel facing downstream and changed orientation prior to passing tail first over the weir crest in the presence and absence of visual cues. The orientation switch was less common when dark. This study shows, at a fine-resolution scale, that downstream movement of juvenile salmonids can be inhibited as fish exhibit alternative behaviours in the absence of visual cues. Downstream movement was not predominantly passive. Fish passage design should not be based on the assumption that downstream migration is passive. [source]

Ion flux through membrane channels,An enhanced algorithm for the Poisson-Nernst-Planck model

JOURNAL OF COMPUTATIONAL CHEMISTRY, Issue 12 2008
Witold Dyrka
Abstract A novel algorithmic scheme for numerical solution of the 3D Poisson-Nernst-Planck model is proposed. The algorithmic improvements are universal and independent of the detailed physical model. They include three major steps: an adjustable gradient-based step value, an adjustable relaxation coefficient, and an optimized segmentation of the modeled space. The enhanced algorithm significantly accelerates the speed of computation and reduces the computational demands. The theoretical model was tested on a regular artificial channel and validated on a real protein channel,,-hemolysin, proving its efficiency. © 2008 Wiley Periodicals, Inc. J Comput Chem, 2008 [source]

Synthesis of Half-Channels by the Anionic Polymerization of Ethylene Oxide Initiated by Modified Cyclodextrin

ADVANCED MATERIALS, Issue 40 2009
Nezha Badi
Amphiphilic star-shaped oligomers are produced by anionic polymerization of ethylene oxide (EO) using per-2,3-di- O -heptyl- , -(or ,)cyclodextrins as initiators , a versatile way of synthesizing artificial channels bearing one polyEO branch per glucose unit. The behavior of the amphiphilic molecules in lipid membranes is studied by electrical measurements, which confirms the formation of transient, well-defined dimeric ionic channels (see figure). [source]

Channels and ditches as the last shelter for freshwater mussels: the case of Margaritifera auricularia and other naiads inhabiting the mid Ebro River Basin, Spain

AQUATIC CONSERVATION: MARINE AND FRESHWATER ECOSYSTEMS, Issue 5 2008
Ignacio Gómez
Abstract 1.Freshwater mussels or naiads are generally considered to thrive in river habitats, provided the ecological conditions are good. The presence of populations of these bivalves in artificial channels and ditches with natural bottoms has only scarcely been reported. The aim of this paper was to present the idea that these ,channel' and ,ditch' habitats could in fact be a sanctuary for naiads. 2.Approximately 80 km of several of these waterways fed by the mid Ebro River were sampled in Spain to monitor their naiad populations. Observations indicate that these habitats harbour substantial colonies of freshwater mussels (including two populations of adult specimens of the endangered species Margaritifera auricularia), much more so than the corresponding river. 3.The authors wish to alert conservation authorities and freshwater mussel experts to the extreme fragility and importance of this kind of habitat for the long-term conservation of these imperilled molluscs. Copyright © 2008 John Wiley & Sons, Ltd. [source]