Sources and sinks separating domains of left- and right-traveling waves:   Experiment versus amplitude equations
  In many pattern forming systems that exhibit traveling waves, sources and sinks occur which separate patches of oppositely traveling waves. We show that simple qualitative features of their dynamics can be compared to predictions from coupled amplitude equations. In heated wire convection experiments, we find a discrepancy between the observed multiplicity of sources and theoretical predictions. The expression for the observed motion of sinks is incompatible with any amplitude equation description. 
Roberto Alvarez, Martin van Hecke and Wim van Saarloos