The TTL output stage is a rather complicated pushâpull circuit known as a totem-pole output (the transistors, diode, and resistor in the right-most slice of this TTL logic gate circuit). It sinks currents better than it sources current.
The theory for spontaneous generation refers to the idea that life can produced from nonliving things. Lazzaro Spallanzani proposed in his experiement that air was necessary for spontaneous generation.
Contagion Theory Gustave Le Bon, a French social psychologist born in 1841, is considered to be the founder of crowd psychology, which explains why people do the things they do in groups. Le Bon's 1895 book, The Crowd: A Study of the Popular Mind, attributed crowd behavior to the 'collective racial unconscious' of the mob overtaking individuals' sense of self and personality and personal responsibility.