Electronic orders near the type-II van Hove singularity in BC3_3

Using the functional renormalization group, we investigate the electron instability in the single-sheet BC$_3$ when the electron filling is near a type-II van Hove singularity. For a finite Hubbard interaction, the ferromagnetic-like spin density wave order dominates in the immediate vicinity of the singularity. Elsewhere near the singularity the p-wave superconductivity prevails. We also find that a small nearest-neighbor Coulomb repulsion can enhance the superconductivity. Our results show that BC$_3$ would be a promising candidate to realize topological $p+ip'$ superconductivity, but the transition temperature is practically sizable only if the local interaction is moderately strong.Comment: 6 pages, 6 color figures. arXiv admin note: text overlap with arXiv:1503.0047

Detecting Expression Patterns of Wnt Pathway Components in Nematostella vectensis Embryos

The anthozoan cnidarian Nematostella vectensis has emerged as a key model system for evolutionary developmental biology studies, and this animal' usefulness will grow with the recent sequencing of its genome. In particular, work done in Nematostella is providing insight into the role of the Wnt pathway in the evolution of pattern formation. This chapter describes methods to maintain and spawn these animals, and detailed protocols to detect expression patterns of Wnt pathway components in Nematostella eggs and embryos

Cnidarian gene expression patterns and the origins of bilaterality – are cnidarians reading the same game plan as "higher" animals?

[Extract] The past few years have seen a dramatic increase in the available data on gene sequence and gene expression for cnidarians and other "lower" Metazoa, and a flurry of recent papers has drawn on these to address the origins of bilaterality. Cnidarianhomologs of many genes that play key roles in the specification of both the A/P and D/V axes of bilaterians have been characterized, and their patterns of expression determined. Some of these expression patterns are consistent with the conservation of function between Cnidaria and Bilateria, but others clearly differ. Moreover, in some cases very different interpretations have been made on the basis of the same, or similar,\ud data. In part, these differences reflect the inevitable uncertainties associated with the depth of the divergence between cnidarians and bilaterians. In this paper we briefly summarize the cnidarian data on gene expression\ud and organization relevant to axis formation, the varying interpretations of these data, and where they conflict. Our conclusion is that the oral-aboral axis probably does correspond to the anterior-posterior axis of bilaterians,\ud but that its polarity remains uncertain, and that many of the same genes are involved in determining the directive axis of cnidarians and the dorsal-ventral axis of bilaterians, but with sufficient differences in expression that exact homologies are uncertain