14 research outputs found
Asymmetric superconductivity in metallic systems
Different types of superfluid ground states have been investigated in systems
of two species of fermions with Fermi surfaces that do not match. This study is
relevant for cold atomic systems, condensed matter physics and quark matter. In
this paper we consider this problem in the case the fermionic quasi-particles
can transmute into one another and only their total number is conserved. We use
a BCS approximation to study superconductivity in two-band metallic systems
with inter and intra-band interactions. Tuning the hybridization between the
bands varies the mismatch of the Fermi surfaces and produces different
instabilities. For inter-band attractive interactions we find a first order
normal-superconductor and a homogeneous metastable phase with gapless
excitations. In the case of intra-band interactions, the transition from the
superconductor to the normal state as hybridization increases is continuous and
associated with a quantum critical point. The case when both interactions are
present is also considered.Comment: new enlarged version, new title, 7 pages, 7 figure
Mutations in the endothelin receptor type A cause mandibulofacial dysostosis with alopecia
The endothelin receptor type A (EDNRA) signaling pathway is essential for the establishment of mandibular identity during development of the first pharyngeal arch. We report four unrelated individuals with the syndrome mandibulofacial dysostosis with alopecia (MFDA) who have de novo missense variants in EDNRA. Three of the four individuals have the same substitution, p.Tyr129Phe. Tyr129 is known to determine the selective affinity of EDNRA for endothelin 1 (EDN1), its major physiological ligand, and the p.Tyr129Phe variant increases the affinity of the receptor for EDN3, its non-preferred ligand, by two orders of magnitude. The fourth individual has a somatic mosaic substitution, p.Glu303Lys, and was previously described as having Johnson-McMillin syndrome. The zygomatic arch of individuals with MFDA resembles that of mice in which EDNRA is ectopically activated in the maxillary prominence, resulting in a maxillary to mandibular transformation, suggesting that the p.Tyr129Phe variant causes an EDNRA gain of function in the developing upper jaw. Our in vitro and in vivo assays suggested complex, context-dependent effects of the EDNRA variants on downstream signaling. Our findings highlight the importance of finely tuned regulation of EDNRA signaling during human craniofacial development and suggest that modification of endothelin receptor-ligand specificity was a key step in the evolution of vertebrate jaws