convective motions would cause it to have a magnetic dynamo, which would change the equatorial stellar radius as indicated by the Applegate’s mechanism [@1987ApJ...322L..99A; @Applegate1992] which should modulate the mass transfer through the inner Lagrangian point. These changes could be observed as cyclic luminosity variations evidenced in the long cycle. This model, proposed by , predicts the correlation between the orbital and long periods and also the value of the long cycle length for particular systems with relatively good accuracy; for the seven studied binaries with orbital periods between 5 and 13 days, the maximum deviation between predicted and observed ratio is 30%, with the average deviation of the order of 12%. Actually, it has been shown that rapid rotation favors the operation of the Applegate’s mechanism .

Other mechanisms have been identified as drivers for mass transfer changes in close binaries. These include direct modulation of mass transfer through the magnetic field of the donor star [@1989SSRv...50..311B; @2004MNRAS.352..416M] and the effect of star spots or prominences [@1994ApJ...427..956L; @1996MNRAS.281..626S; @2004MNRAS.352..416M].

Recently, MgII, FeI, FeII, CI and TiII emission lines that are signatures of chromospherically active stars were detected in V393Scorpii, supporting the existence of magnetically active donors in DPVs [@2018PASP..130i4203M]. 