in hydraulic engineering, a segment of a river where the structures of a hydroengineering complex are located and where the pressure front is formed by the structures. There are usually two steps involved in the selection of a site. First, a site region is designated in conformity with a general plan for managing the water of the particular river, and then a site axis is determined. The axis is understood as a strip of a certain width that cuts across the river and valley; it may be straight, that is, perpendicular to the banks of the river, curvilinear, or broken. An optimal choice of the site is arrived at by a comparison, from both a technical and economic point of view, of the various alternatives with due regard for climatic, topographical, hydrological, geological, and construction conditions.
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Mu opioid receptors mediate positive reinforcement following direct (morphine) or indirect (alcohol, cannabinoids, nicotine) activation, and our understanding of mu receptor function is central to the development of addiction therapies. Recent data obtained in native neurons confirm that mu receptor signaling and regulation are strongly agonist-dependent. Current functional mapping reveals morphine-activated neurons in the extended amygdala and early genomic approaches have identified novel mu receptor-associated proteins. A classification of about 30 genes either promoting or counteracting the addictive properties of morphine is proposed from the analysis of knockout mice data. The targeting of effectors or regulatory proteins, beyond the mu receptor itself, might provide valuable strategies to treat addictive disorders.