Topological phases of non-Hermitian systems

Recent experimental advances in controlling dissipation have brought about unprecedented flexibility in engineering non-Hermitian Hamiltonians in open classical and quantum systems. A particular interest centers on the topological properties of non-Hermitian systems, which exhibit unique phases with no Hermitian counterparts. However, no systematic understanding in analogy with the periodic table of topological insulators and superconductors has been achieved. In this paper, we develop a coherent framework of topological phases of non-Hermitian systems. After elucidating the physical meaning and the mathematical definition of non-Hermitian topological phases, we start with one-dimensional lattices, which exhibit topological phases with no Hermitian counterparts and are found to be characterized by an integer topological winding number even with no symmetry constraint, reminiscent of the quantum Hall insulator in Hermitian systems. A system with a nonzero winding number, which is experimentally measurable from the wave-packet dynamics, is shown to be robust against disorder, a phenomenon observed in the Hatano-Nelson model with asymmetric hopping amplitudes. We also unveil a novel bulk-edge correspondence that features an infinite number of (quasi-)edge modes. We then apply the K-theory to systematically classify all the non-Hermitian topological phases in the Altland-Zirnbauer classes in all dimensions. The obtained periodic table unifies time-reversal and particle-hole symmetries, leading to highly nontrivial predictions such as the absence of non-Hermitian topological phases in two dimensions. We provide concrete examples for all the nontrivial non-Hermitian AZ classes in zero and one dimensions. In particular, we identify a Z2 topological index for arbitrary quantum channels. Our work lays the cornerstone for a unified understanding of the role of topology in non-Hermitian systems.Comment: 31 pages, 18 figures, 2 tables, to appear in Physical Review

TGF-β regulates isoform switching of FGF receptors and epithelial–mesenchymal transition

Both TGF-β and FGF signalling regulate the epithelial–mesenchymal transition. Here, TGF-β is found to promote myofibroblast differentiation, while concomitant FGF pathway activation instead drives cells towards an invasive mesenchymal fate

次世代エネルギー社会の鍵を握る超伝導技術の最前線

ISEE先端サマーセミナー2017 最先端システム情報科学の世界 できるコトと見えるモノ : 九州大学大学院システム情報科学府・研究院 : 2017年8月10日(木) 9:20～15：30 : 九州大学伊都キャンパ

Anti PD-1 treatment increases [F-18]FDG uptake by cancer cells in a mouse B16F10 melanoma model

Background: Programmed cell death 1 (PD-1) inhibitors act as immune checkpoint inhibitors and are more effective for improving survival time with less toxicity as compared with conventional chemotherapies. In anti PD-1 therapy, it is important to evaluate metabolism in the cancer microenvironment, as this helps to clarify the pathological conditions. Herein, we investigate the early effects of PD-1 therapy on 2-deoxy-2-[F-18]fluoro-D-glucose ([F-18]FDG) uptake in vivo, focusing on cell distribution and glycolysis in both cancer and immune cells. Results: In a B16F10 melanoma model, [F-18]FDG-positron emission tomography (PET) was performed before treatment and 7 days after the start of treatment. Values were calculated as the percentage-injected activity per gram of tissue (%IA/g). Flow-cytometry was then performed to assess immune cell populations and glucose metabolism. There was a negligible difference in [18F]FDG uptake between tumors in the treatment group and non-treatment group before the treatment. In contrast, mean [F-18]FDG uptake in the treatment group tumors was significantly higher (8.06 +/- 0.48 %IA/g; P= 0.0074) than that in the non-treatment group (4.02 +/- 1.03 %IA/g) after anti PD-1 treatment. Assessment of tumor immune cell populations showed that treatment slightly enriched CD8(+) T cells and CD4(+) T cells; however, infiltration of immune cells was negligible, and thus, immune cells were not responsible for the increase in [F-18]FDG uptake. On the other hand, anti PD-1 treatment significantly increased glucose transporter 1 (GLUT1) and hexokinase II expression in CD45(-) cancer cells, indicating that anti PD-1 treatment increased glucose metabolism in cancer cells. Conclusion: The present study shows that anti PD-1 therapy increases glucose metabolism in cancer cells

Performance improvement of YBCO coil for high-field HTS-SMES based on homogenized distribution of magnetically-mechanically influenced critical current

Generally speaking for a HTS coil, perpendicular magnetic field to conductor's broad surface should be suppressed as small as possible in relation to the magnetic anisotropy. This is a reason why toroidal coil with relatively many elementary coils is expected for HTS-SMES. On the other hand, from the point of view of the homogenization of critical current distribution in the coil, perpendicular field and parallel field should be balanced corresponding to the ratio of the magnetic anisotropy. This means that a certain level of the perpendicular field is effective to reduce local heat generation in the coil. Furthermore, this concept is especially reasonable for a high-field coil with usual winding method (flat-wise winding) because the perpendicular field does not induce hoop stress which decreases the critical current. In this paper, we show these findings through an optimal design of a MOCVD-YBCO toroidal coil for 2 GJ class SMES taking account of magnetically and mechanically influenced J - E characteristics