Both TPTPS and SD4 are due to duplications involving ZRS, the limb specific SHH enhancer. Point mutations in the ZRS and duplications encompassing the ZRS cause distinctive limb phenotypes.

A series of mesogen-jacketed liquid crystalline polymers, poly{2,5-bis[(4-butoxyphenyl)oxycarbonyl]-styrenes} (PBPCS), with a wide range of molecular weights (M n ) 1.24 × 10 4 -35.6 × 10 4 ) and narrow molecular weight distributions (M w /M n e 1.18) have been synthesized by atom transfer radical polymerization. The resulting polymers have been investigated by a combination of techniques including differential scanning calorimetry, polarized optical microscopy, and X-ray scattering. The samples with M n e 2.42 × 10 4 are isotropic. The samples with M n g 3.36 × 10 4 display a thermodynamically stable isotropic phase at lower temperature and a liquid crystalline (LC) phase at higher temperature. The phase behavior shows a phenomenon quite similar to the reentrant isotropic phase. These transitions are correlated with the rheological properties measured as a function of temperature. The rheological behavior of the polymer in the isotropic phase and in the LC phase has been studied as well. On the basis of these experimental observations, a generalized phase diagram is constructed for the polymers showing the influence of the molecular weight on the phase transition temperature. It is illustrated that LC phase is formed through a global change of the whole molecule from the coiled to extended chain conformation accompanied by an increase of the entropy. Higher entropy originating from the free mobilities of bulky side chains in LC phase has been proposed to be an important factor to stabilize the LC phase.

We study the noise-driven escape of active Brownian particles (ABPs) and run-and-tumble particles (RTPs) from confining potentials. In the small noise limit, we provide an exact expression for the escape rate in term of a variational problem in any dimension. For RTPs in one dimension, we obtain an explicit solution, including the first sub-leading correction. In two dimensions we solve the escape from a quadratic well for both RTPs and ABPs. In contrast to the equilibrium problem we find that the escape rate depends explicitly on the full shape of the potential barrier, and not only on its height. This leads to a host of unusual behaviors. For example, when a particle is trapped between two barriers it may preferentially escape over the higher one. Moreover, as the self-propulsion speed is varied, the escape route may discontinuously switch from one barrier to the other, leading to a dynamical phase transition. arXiv:1904.00599v2 [cond-mat.soft]