Dirac Surface States in Magnonic Analogs of Topological Crystalline Insulators.

We propose magnonic analogs of topological crystalline insulators which possess Dirac surface states protected by the combined symmetry of time reversal and half translation. Constructing models of the topological magnon systems, we demonstrate that an energy current flows through the systems in response to an electric field, owing to the Dirac surface states with the spin-momentum locking. We also propose a realization of the magnonic analogs of topological crystalline insulators in the magnetic compound CrI_{3} with a monoclinic structure.

Effects of Food-Derived Collagen Peptides on the Expression of Keratin and Keratin-Associated Protein Genes in the Mouse Skin.

Oral ingestion of collagen peptides (CP) has long been suggested to exert beneficial effects on the skin, but the molecular events induced by CP on the skin remain unclear. Here, we investigated the effects of oral CP administration on gene expression in hairless mouse skin and of prolyl-hydroxyproline (Pro-Hyp), a collagen-derived dipeptide, on gene expression in a coculture of mouse skin keratinocytes and fibroblasts. Using microarray analysis, we found that oral administration of CP to hairless mice for 6 weeks induced increased expression of Krtap and Krt genes in the skin. Annotation analysis using DAVID revealed that a group of the up-regulated genes, Gprc5d, Sprr2a1, Krt27 and Krtap16-7, is associated with the development of the epidermis and the hair cycle. In addition, the presence of Pro-Hyp (200 µM) induced an increase in the expression of Krtap16-7, Krtap15, Krtap14 and Krtap8-2 in keratinocytes in coculture, partially resembling the in vivo result. The Pro-Hyp-induced up-regulation of these genes was not observed when keratinocytes were cultured without fibroblasts, suggesting that the presence of fibroblasts is essential for the effects of Pro-Hyp. Our study presents new insights into the effects of CP on the skin, which might link to the hair cycle.

Hidden multiple-spin interactions as an origin of spin scalar chiral order in frustrated Kondo lattice models.

We reveal the significance of kinetic-driven multiple-spin interactions hidden in geometrically frustrated Kondo lattice models. Carefully examining the perturbation in terms of the spin-charge coupling up to the fourth order, we find that a positive biquadratic interaction is critically enhanced and plays a crucial role on stabilizing a spin scalar chiral order near 1/4 filling in a triangular lattice case. This is a generalized Kohn anomaly, appearing only when the second-order perturbation is inefficient because of the degeneracy under frustration. The mechanism is potentially common to frustrated spin-charge coupled systems, leading to emergence of unusual magnetic orders.

Transforming generalized Ising models into Boltzmann machines.

We find an exact mapping from the generalized Ising models with many-spin interactions to equivalent Boltzmann machines, i.e., the models with only two-spin interactions between physical and auxiliary binary variables accompanied by local external fields. More precisely, the appropriate combination of the algebraic transformations, namely the star-triangle and decoration-iteration transformations, allows one to express the model in terms of fewer-spin interactions at the expense of the degrees of freedom. Furthermore, the benefit of the mapping in Monte Carlo simulations is discussed. In particular, we demonstrate that the application of the method in conjunction with the Swendsen-Wang algorithm drastically reduces the critical slowing down in a model with two- and three-spin interactions on the Kagomé lattice.