They may be installed either upstream or downstream of a regulator or meter, and may be controlled directly or from a remote pressure source by means of an external control line.

它们可安装于减压阀或计量表上下游，并可直接控制或以外接远端压力源控制线做远端控制。

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Methods are already being developed to implant a light source inside the body which could be activated by remote control.

ECONOMIST: Neurology