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Disturbances in internal water equilibrium can be debilitating for mammals. Two studies pinpoint areas of the mouse brain that respond to and anticipate thirst, preserving systematic fluid regulation. See Letters p.680 & p.685 It is vital for mammals to maintain their internal water equilibrium. The neurobiological mechanisms linking thirst response behaviour and fluid balance maintenance raise intriguing questions, given that these two components operate on different timescales. Two papers in this issue of Nature identify areas of the mouse brain that respond to and anticipate thirst. Zachary Knight and colleagues reveal a role for thirst-promoting neurons in the subfornical organ (SFO). During eating and drinking, feedback from the oral cavity to the SFO—one of the three sensory circumventricular organs of the brain—is integrated with information regarding blood composition, providing an indication of how oral consumption is likely to alter fluid balance, leading to behavioural adjustments. Charles Bourque and colleagues identify a projection from central clock neurons that drives anticipatory water intake just prior to sleep, regardless of physiological need. Without this specifically timed increase in water intake, animals suffered from dehydration near the end of a period of sleep.

Water can be a scarce resource, particularly in certain places at certain times. Understanding both water use and conservation efforts can help ensure that limited supplies can meet the demands of a growing population and economy. This paper examines water use and recirculation in the U.S. manufacturing sector, using newly recovered microdata from the (defunct) Survey of Water Use in Manufacturing, merged with establishment-level data from the Annual Survey of Manufactures and the Census of Manufactures. Results suggest that water use per unit of output is largest for larger establishments, in part because larger establishments use water for more purposes. Larger establishments are also found to recirculate water more – satisfying water use needs without necessarily increasing water intake. Various costs also appear to play a role in water recirculation. In particular, the water circulation rate is found to be higher when water is purchased from a utility. Relatively low (internal) prices for self-supplied water could suppress the incentive to invest in recirculation. Meanwhile, establishments with higher per-gallon water intake treatment costs also recirculate more, as might be expected. The cost associated with water discharge – due to regulation or otherwise – also increases circulation rates. The aridity of a locale is found to have little effect on circulation rates.

In paper, researches of riverbed and hydraulic processes at the water intake from mountain rivers are observed. Classification of designs of the mountain water intake structures, based on continuity signs is offered. Perfecting of base designs of water intake structures of a mountain-foothill zone and means of their hydraulic automation is carried out. The technological, theoretical and experimental substantiation of parameters of basic elements of these designs with a glance of hydromorphometric characteristics of the mountain rivers is given. Complex hydraulic researches of kinematic characteristics and carrying ability of a two-phase stream on water intake structures are executed. Bases of a technique of engineering calculation of the offered designs of water intake structures and the recommendation of their designing and maintenance in various hydrological regimes are developed.