Simmel conveys how cohesion has played a role in distinguishing between a dyad a triad. A pair of sister chromatids is called a dyad. Add one individual to a dyad, and you have a triad. Furthermore, cardiac muscle tend to exhibit diad (or dyad) structures, rather than triads. This motif is responsible for facilitating the Asp-His dyad mechanism seen in many serine proteases. Dyadic level&colon; A dyad is a social relationship between two individuals. To Plotinus, the second emanation represents an uncreated second cause (see Pythagoras' Dyad). Giovanni Reale emphasized the role of the Dyad as a fundamental origin. In Rome, the plebeians were insistent about the dyad of consuls. Sometimes even a single interval (dyad) is considered a chord. Mann and Weil now operate a publishing company named Dyad Music. Finally cystine-192 and histidine-340 form a catalytic dyad. The mesosystem moves us beyond the dyad or two-party relation. Line 1 corresponds to a point, and Line 2 corresponds to a line segment (dyad). All Being rests upon the action of the One upon the Indefinite Dyad.