Kinetic roughening of coffee-ring interfaces

Por Beatriz García Barreales (Departamento de Física, Facultad de Ciencias, Universidad de Extremadura, Badajoz, Spain).

14h00-14h30

We have studied the kinetic roughening behavior of the fronts of coffee-ring aggregates via extensive numerical simulations of the off-lattice model considered for this context in [C. S. Dias et al., Soft Matter 14, 1903 (2018)]. This model describes ballistic aggregation of patchy colloids and depends on a parameter rAB which controls the affinity of the two patches, A and B. 

For long times, large lattice and all rAB-values we have found that the dynamic is dominated by the appearance of macroscopic shapes.  The intermediate (time) dynamics is different depending of the value of rAB.  A detailed analysis of correlation functions shows that the front for the discrete model is always in the moving phase for 0<rAB≤1 and that its kinetic roughening behavior is intrinsically anomalous for rAB<0.1. Suitable boundary conditions allow us to elucidate a discontinuous pinning transition at rAB=0, with the front still displaying intrinsic anomalous scaling, but now with unusual exponent values α⋍1.2, αloc⋍0.5, β⋍1, and z⋍1.2.

Capturing Joint Behavioral States in Zebrafish (Danio rerio) Fights

Por Rafael Almada (Faculdade de Ciências, Universidade de Lisboa, Portugal).

14h30-15h00

Animal behavior is a fascinating area from a physical perspective and yet there are several challenges in making physical models about it. A specific challenge comes from deriving models  from data, removing human-centric bias when defining behaviors. A good example of the complexity associated with this task can be seen in animal contests, such as in zebrafish (Danio rerio) fights or dyadic contests. Our work consisted mainly of deriving behavioral states of this interaction, using simple physical interpretable variables. Using techniques from signal processing and symbolic analysis, we are able to recover a representation of these behavioral states, possibly capturing a larger structure of a contest.