The mesoderm of the amphibian embryo is formed through an inductive interaction in which cells of the vegetal hemisphere of the embryo act on overlying equatorial cells. My laboratory is studying the Brachyury gene, which plays a key role in this interaction, being both necessary and sufficient for normal mesoderm formation. In this article I describe our attempts to understand how Xenopus Brac...

Local scouring in the downstream of hydraulic structures is one of the important issues in river and hydraulic engineering, which involves a lot of costs every year, so the prediction of the rate of scour is important in hydraulic design. Side weirs are the most important of hydraulic structures that are used in passing flow. This study investigate the scouring due to falling jet from side weir...

upstream blankets, drains and cutoff walls are considered as effective measures to reduce seepage, uplift pressure and exit gradient under the foundation of hydraulic structures. to investigate the effectiveness of these measures, individually or in accordance with others, a large number of experiments were carried out on a laboratory model. to extend the investigation for unlimited arrangement...

an experiment featuring waterhammer in viscoelastic pipes is presented in which the effects of pipe-wall viscoelasticity on waterhammer pressures are investigated. a large-scale pipeline apparatus made of polyvinyl chloride (pvc) at deltares, delft, the netherlands, has been used to carry out waterhammer experiments. tests have been conducted in a reservoir-pipeline-valve system consisting of a...

this study was conducted to evaluate the morphological responses of two different species including capoeta gracilis and alburnoides eichwaldii due to construction of the tarik dam in the sefidrud river using geometric morphometric technique. for this purpose, a total of 80 specimens of c. gracilis and 60 specimens of a. eichwaldii were collected from upstream and down-stream of dam. the left s...

Relief wells are used extensively to relieve excess hydrostatic pressure in pervious foundation strata overlain by impervious top strata, conditions which often exist landward of levees and downstream of dams and hydraulic structures. Placing well outlets in below-surface trenches or collector pipes helps dry up seepage areas downstream of levees and dams. Relief wells are often used in combina...