Abstract: A method of regulating gas pressure in a dual fluid fuel injection system for an internal combustion engine having at least one delivery injector, including; determining when the gas pressure supplied to the fuel injection system is above a desired level; and opening the at least one delivery injector of the dual fluid fuel injection system for a determined duration when the gas pressure is above the desired level to allow gas to be passed through the delivery injector and thereby regulate the gas pressure of the supplied gas.

Abstract: A method for determining and monitoring tissue glucose concentration, wherein a perfusion solution is conveyed as a liquid column through a microdialysis probe implanted in the tissue and is moved to a test cell preferably arranged outside the patient's body, the volumetric flow of the perfusion solution being reduced in its time average for the duration of the dialysis intervals (T.sub.1) and the volume of the perfusion solution perfused through the microdialysis probe during each dialysis interval (T.sub.1) being moved on in a consecutive transport interval (T.sub.2) at a higher volumetric flow to the test cell and wherein the glucose content of the perfusion solution passing through the test cell is determined from continuously detected test signals, characterized in that before passing through the microdialysis probe the perfusion solution is mixed with glucose in order to set a predetermined initial concentration.