Electromagnetic and thermal responses in topological matter: topological terms, quantum anomalies and D-branes

We discuss the thermal (or gravitational) responses in topological superconductors and in topological phases in general. Such thermal responses (as well as electromagnetic responses for conserved charge) provide a definition of topological insulators and superconductors beyond the single-particle picture. In two-dimensional topological phases, the Str\v{e}da formula for the electric Hall conductivity is generalized to the thermal Hall conductivity. Applying this formula to the Majorana surface states of three-dimensional topological superconductors predicts cross-correlated responses between the angular momentum and thermal polarization (entropy polarization). We also discuss a use of D-branes in string theory as a systematic tool to derive all such topological terms and topological responses. In particular, we relate the $\mathbb{Z}_2$ index of topological insulators introduced by Kane and Mele (and its generalization to other symmetry classes and to arbitrary dimensions) to the K-theory charge of non-BPS D-branes, and vice versa. We thus establish a link between the stability of non-BPS D-branes and the topological stability of topological insulators.Comment: 16 pages, 2 figures; Submitted to a topical issue of the Comptes Rendus de l Academie des Sciences (CRAS

Herbimycin A suppresses NF-κB activation and tyrosine phosphorylation of JAK2 and the subsequent induction of nitric oxide synthase in C6 glioma cells

AbstractHerbimycin A, a potent tyrosine kinase inhibitor, suppressed nitric oxide synthase (NOS) induced by lipopolysaccharide (LPS) and interferon-γ (IFN-γ) in C6 glial cells. LPS activated NF-κB, and this effect was inhibited by pretreatment with herbimycin A. In addition, IFN-γ activated the tyrosine protein kinase, JAK2, and tyrosine-phosphorylation by itself was also inhibited by herbimycin A. These results suggest that herbimycin A suppresses iNOS induction by inhibition of both NF-κB activation caused by LPS, and tyrosine-phosphorylation of JAK2 caused by IFN-γ in C6 glioma cells

Reconstruction of ancestral brains: Exploring the evolutionary process of encephalization in amniotes

AbstractThere is huge divergence in the size and complexity of vertebrate brains. Notably, mammals and birds have bigger brains than other vertebrates, largely because these animal groups established larger dorsal telencephali. Fossil evidence suggests that this anatomical trait could have evolved independently. However, recent comparative developmental analyses demonstrate surprising commonalities in neuronal subtypes among species, although this interpretation is highly controversial. In this review, we introduce intriguing evidence regarding brain evolution collected from recent studies in paleontology and developmental biology, and we discuss possible evolutionary changes in the cortical developmental programs that led to the encephalization and structural complexity of amniote brains. New research concepts and approaches will shed light on the origin and evolutionary processes of amniote brains, particularly the mammalian cerebral cortex