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.
One of these group of composers were called the generazione dell'ottanta (generation of 1880), including Franco Alfano, Alfredo Casella, Gian Francesco Malipiero, Ildebrando Pizzetti, and Ottorino Respighi. Even opera composers, such as Giuseppe Verdi, occasionally worked in these forms.