S Your new gas furnace may have been installed in one of two. ways, as a direct-vent (2-pipe-Fig. 2) application or as a. non-direct vent (1-pipe-Fig. 3) application. S In a direct-vent (2-pipe) application,your furnace uses air. from outside the home for combustion and ventsflue gas to the. outdoors.
For the biological concept, see Anti-predator adaptation. A defence mechanism is an unconscious psychological mechanism that reduces anxiety arising from unacceptable or potentially harmful stimuli. Sigmund Freud was one of the first proponents of this construct.
In short, defense mechanisms are one of our commonest ways to cope with unpleasant emotions. Although Freud and many of his followers believed that we use them to combat sexual or aggressive feelings, defense mechanisms apply to a wide range of reactions from anxiety to insecurity.