Spin-Nernst Effect in Time-Reversal-Invariant Topological Superconductors.

We investigate the spin-Nernst effect in time-reversal-invariant topological superconductors, and show that it provides smoking-gun evidence for helical Cooper pairs. The spin-Nernst effect stems from asymmetric, in spin space, scattering of quasiparticles at nonmagnetic impurities, and generates a transverse spin current by the temperature gradient. Both the sign and the magnitude of the effect sensitively depend on the scattering phase shift at impurity sites. Therefore the spin-Nernst effect is uniquely suitable for identifying time-reversal-invariant topological superconducting orders.

Emergent dynamic chirality in a thermally driven artificial spin ratchet.

Modern nanofabrication techniques have opened the possibility to create novel functional materials, whose properties transcend those of their constituent elements. In particular, tuning the magnetostatic interactions in geometrically frustrated arrangements of nanoelements called artificial spin ice can lead to specific collective behaviour, including emergent magnetic monopoles, charge screening and transport, as well as magnonic response. Here, we demonstrate a spin-ice-based active material in which energy is converted into unidirectional dynamics. Using X-ray photoemission electron microscopy we show that the collective rotation of the average magnetization proceeds in a unique sense during thermal relaxation. Our simulations demonstrate that this emergent chiral behaviour is driven by the topology of the magnetostatic field at the edges of the nanomagnet array, resulting in an asymmetric energy landscape. In addition, a bias field can be used to modify the sense of rotation of the average magnetization. This opens the possibility of implementing a magnetic Brownian ratchet, which may find applications in novel nanoscale devices, such as magnetic nanomotors, actuators, sensors or memory cells.

Investigating the epidemiological and economic effects of a third-party certification policy for restaurants with COVID-19 prevention measures.

This study investigates the effects of a third-party certification policy for restaurants (including bars) that comply with indoor infection-prevention measures on COVID-19 cases and economic activities. We focus on the case of Yamanashi Prefecture in Japan, which introduced a third-party certification policy that accredits facilities, predominantly restaurants, that comply with the designated guidelines. We employ a difference-in-differences design for each of our epidemiological and economic analyses. The estimation results show that, from July 2020 to April 2021, the certification policy reduced the total number of new infection cases by approximately 45.3% (848 cases), while increasing total sales and the number of customers per restaurant by approximately 12.8% (3.21 million Japanese yen or $30,000) and 30.3% (2909 customers), respectively, compared to the non-intervention scenarios. The results suggest that a third-party certification policy can be an effective policy to mitigate the trade-off between economic activities and infection prevention during a pandemic, especially when effective vaccines are not widely available.

A new source of cytoplasmic male sterility found in wild beet and its relationship to other CMS types.

We found a number of male-sterile plants in a wild beet (Beta vulgaris L. subsp. maritima) accession line, FR4-31. The inheritance study of the male sterility indicated the trait to be of the cytoplasmic type. The mitochondrial genome of FR4-31 proved to lack the male-sterility-associated genes preSatp6 and orf129, which are characteristic of the Owen CMS and I-12CMS(3) cytoplasms of beets, respectively. Instead, the truncated cox2 gene involved in G CMS originating from wild beets was present in the FR4-31 mitochondrial genome. In Southern hybridization using four mitochondrial gene probes, the FR4-31 cytoplasm showed patterns similar to those typical of the G cytoplasm. It is thus likely that the FR4-31 cytoplasm has a different CMS mechanism from both Owen CMS and I-12CMS(3), and that the FR4-31 and G cytoplasms resemble each other closely. A restriction map of the FR4-31 mitochondrial DNA was generated and aligned with those published for the Owen and normal fertile cytoplasms. The FR4-31 mitochondrial genome was revealed to differ extensively in arrangement from the Owen and normal genomes, and the male-sterile Owen and FR4-31 genomes seem to be derived independently from an ancestral genome.

Optical investigations of the (dis)continuous metal-insulator transitions in strongly-coupled electron-lattice systems.

Optical properties of four model systems (Na-, K-, Rb- or Cs-doped quasi-two-dimensional X 1.95Al1.95Si2.05O8.00; X = Na, K, Rb, or Cs) used to study the metal-insulator transition (MIT) in a deformable lattice are investigated. The doping evolution of the optical absorption band(s) originating from small bipolarons show strong variations depending on the electron-lattice coupling strength [Formula: see text]. Despite the increasing number density of small (bi)polarons, the Na-system remains a stubborn (bi)polaronic insulator due to strong [Formula: see text], while the other three systems show closing of the respective mobility gaps giving way to conducting phases with differing properties. These interesting evolutions and dynamical properties are compared and discussed. We conjecture that the manifestation of anomalous electronic transport properties and Mooij correlations near the MIT or superconductor-insulator transition in systems with non-negligible electron-lattice coupling effects may be linked to the coexistence of competing polaronic phases and the dynamical intertwining of the deformable lattice and the random electronic potential.