263 research outputs found
Chemo-capillary instabilities of a contact line
Equilibrium and motion of a contact line are viewed as analogs of phase
equilibrium and motion of an interphase boundary. This point of view makes
evident the tendency to minimization of the length of the contact line at
equilibrium. The concept of line tension is, however, of limited applicability,
in view of a qualitatively different relaxation response of the contact line,
compared to a two-dimensional curve. Both the analogy and qualitative
distinction extend to a non-equilibrium situation arising due to coupling with
reversible substrate modification. Under these conditions, the contact line may
suffer a variety of chemo-capillary instabilities (fingering, traveling and
oscillatory), similar to those of dissipative structures in nonlinear
non-equilibrium systems. The preference order of the various instabilities
changes, however, significantly due to a different way the interfacial
curvature is relaxed.Comment: 8 pages, 4 figures; corrected version of the published pape
The biological frontier of pattern formation
Morphogenetic patterns are highly sophisticated dissipative structures. Are
they governed by the same general mechanisms as chemical and hydrodynamic
patterns? Turing's symmetry breaking and Wolpert's signalling provide
alternative mechanisms. The current evidence points out that the latter is more
relevant but reality is still far more complicated.Comment: 9 pages, 0 figure
Turing patterns and solitary structures under global control
Striped Turing patterns and solitary band and disk structures are constructed
using a three-variable multiscale model with cubic nonlinearity and global
control. The existence and stability conditions of regular structures are
analysed using the equation of motion of curved boundaries between alternative
states of the short-range component. The combined picture of transitions
between striped and spotted patterns with changing level of global control is
in qualitative agreement with the results of the computer experiment by Middya
and LussComment: RevTeX 30 pages, 10 PS-figure
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