Granular flow regimes in rotating drums from depth-integrated theory.

Granular flows in rotating drums transition between two regimes characterized by straight and curved free surfaces. Here we predict this behavior using a depth-integrated theory applicable to general eroding flows. Closure is achieved by a local µ(I) rheology and an equation for kinetic energy. Spanning the transition, the theory yields relations for all flow properties in terms of a single dimensionless rotation rate. In accord with experiments, distinct scaling laws are obtained for slow and fast rates, dominated respectively by local energy dissipation and longitudinal energy transfer.

The medial amygdaloid nucleus modifies social behavior in male rats.

Electrical stimulation of the medial amygdaloid nucleus (AME) produces a behavioral state in male rats that resembles the postejaculatory interval, but electrical recording from cells in the AME shows that they become active earlier in sexual behavior, around the time that the male first appears to become aware of estrus in the female. In an attempt to resolve which feature of sexual behavior was mediated by the AME, we stimulated the structure bilaterally in freely behaving males using voltage levels too low to produce the postejaculatory interval. We found that electrical activation of this kind facilitated sexual behavior when it would not otherwise occur (i.e., in the presence of a nonestrous female). However, the stimuli suppressed sexual behavior when it would normally occur (i.e., in the presence of a nonestrous female). We discuss alternative interpretations of the results in the context of a general model for the central organization of sexual behavior in males.