The Potts Fully Frustrated model: Thermodynamics, percolation and dynamics in 2 dimensions

We consider a Potts model diluted by fully frustrated Ising spins. The model corresponds to a fully frustrated Potts model with variables having an integer absolute value and a sign. This model presents precursor phenomena of a glass transition in the high-temperature region. We show that the onset of these phenomena can be related to a thermodynamic transition. Furthermore this transition can be mapped onto a percolation transition. We numerically study the phase diagram in 2 dimensions (2D) for this model with frustration and {\em without} disorder and we compare it to the phase diagram of $i)$ the model with frustration {\em and} disorder and of $ii)$ the ferromagnetic model. Introducing a parameter that connects the three models, we generalize the exact expression of the ferromagnetic Potts transition temperature in 2D to the other cases. Finally, we estimate the dynamic critical exponents related to the Potts order parameter and to the energy.Comment: 10 pages, 10 figures, new result

Function of the Tetraspanin CD151–α6β1 Integrin Complex during Cellular Morphogenesis

Upon plating on basement membrane Matrigel, NIH3T3 cells formed an anastomosing network of cord-like structures, inhibitable by anti-α6β1 integrin antibodies. For NIH3T3 cells transfected with human CD151 protein, the formation of a cord-like network was also inhibitable by anti-CD151 antibodies. Furthermore, CD151 and α6β1 were physically associated within NIH3T3 cells. On removal of the short 8-amino acid C-terminal CD151 tail (by deletion or exchange), exogenous CD151 exerted a dominant negative effect, as it almost completely suppressed α6β1-dependent cell network formation and NIH3T3 cell spreading on laminin-1 (an α6β1 ligand). Importantly, mutant CD151 retained α6β1 association and did not alter α6β1-mediated cell adhesion to Matrigel. In conclusion, the CD151–α6β1 integrin complex acts as a functional unit that markedly influences cellular morphogenesis, with the CD151 tail being of particular importance in determining the “outside-in” functions of α6β1-integrin that follow ligand engagement. Also, antibodies to α6β1 and CD151 inhibited formation of endothelial cell cord-like networks, thus pointing to possible relevance of CD151–α6β1 complexes during angiogenesis