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.
1794 â Physiologist Lazzaro Spallanzani was the first to study echolocation among bats, which forms the basis for ultrasound physics. 1877 â Brothers Pierre and Jacques Currie discover piezoelectricity. Ultrasound transducers (probes) emit and receive sound waves by way of the piezoelectric effect.