Robustness of the semimetal state of Na3Bi and Cd3As2 against Coulomb interaction

We study the excitonic semimetal-insulator quantum phase transition in three-dimensional Dirac semimetal in which the fermion dispersion is strongly anisotropic. After solving the Dyson-Schwinger equation for the excitonic gap, we obtain a global phase diagram in the plane spanned by the parameter for Coulomb interaction strength and the parameter for fermion velocity anisotropy. We find that excitonic gap generation is promoted as the interaction becomes stronger, but is suppressed if the anisotropy increases. Applying our results to two realistic three-dimensional Dirac semimetals Na$_{3}$Bi and Cd$_{3}$As$_{2}$, we establish that their exact zero-temperature ground state is gapless semimetal, rather than excitonic insulator. Moreover, these two materials are far from the excitonic quantum critical point, thus there should not be any observable evidence for excitonic insulating behavior. This conclusion is in general agreement with the existing experiments of Na$_{3}$Bi and Cd$_{3}$As$_{2}$.Comment: 12 pages, 5 figure

Suppression of Type I Interferon Signaling by Flavivirus NS5.

Type I interferon (IFN-I) is the first line of mammalian host defense against viral infection. To counteract this, the flaviviruses, like other viruses, have encoded a variety of antagonists, and use a multi-layered molecular defense strategy to establish their infections. Among the most potent antagonists is non-structural protein 5 (NS5), which has been shown for all disease-causing flaviviruses to target different steps and players of the type I IFN signaling pathway. Here, we summarize the type I IFN antagonist mechanisms used by flaviviruses with a focus on the role of NS5 in regulating one key regulator of type I IFN, signal transducer and activator of transcription 2 (STAT2)

Emergence, Evolution and Scaling of Online Social Networks

This work was partially supported by AFOSR under Grant No. FA9550-10-1-0083, NSF under Grant No. CDI-1026710, NSF of China under Grants Nos. 61473060 and 11275003, and NBRPC under Grant No. 2010CB731403. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.Peer reviewedPublisher PD