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.
The term Lebensraum was coined by the German geographer, Friedrich Ratzel (1844-1904). During the last two decades of the 19th century, Ratzel developed a theory according to which the development of all species, including humans, is primarily determined by their adaptation to geographic circumstances.