Omnidirectional acoustic cloaking against airborne sound realized by a locally resonant sonic material.

We report that a locally resonant sonic material realizes omnidirectional acoustic invisibility in air. To achieve acoustic cloaking in the low-frequency regime, we axisymmetrically placed elastic rods comprised of silicone rubber and lead around a cloaked object. The radii of the rods are designed to minimize their total scattering cross section for a given frequency. The optimization is performed using an algorithm incorporating multiple scattering theory and gradient-based nonlinear programming. We numerically confirmed that the designed cloaking device suppressed the scattering cross section by almost 92% for all incident directions at the target frequency.

Unidirectional invisibility in a PT-symmetric structure designed by topology optimization.

This study designs a piecewise homogeneous dielectric structure with parity-time (PT) symmetry that realizes the unidirectional invisibility of a perfect electric conductor in two dimensions. We apply topology optimization and design a PT-symmetric material that minimizes the total scattering cross section for a given plane wave to achieve unidirectional invisibility. A rigorous mode-matching finite element method is used to perform all computations. The designed PT-symmetric structure suppressed plane-wave scattering by approximately 99% for the given incident direction, whereas the reversed incident wave experienced 83 times larger scattering intensity. The proposed method provides a novel approach, to the best of our knowledge, to promote various applications of PT symmetry.

Improving the standards for gut microbiome analysis of fecal samples: insights from the field biology of Japanese macaques on Yakushima Island.

Fecal DNA-based 16S ribosomal RNA (rRNA) gene sequencing using next-generation sequencers allows us to understand the dynamic gut microbiome adaptation of animals to their specific habitats. Conventional techniques of fecal microbiome analysis have been developed within the broad contexts defined by human biology; hence, many of these techniques are not immediately applicable to wild nonhuman primates. In order to establish a standard experimental protocol for the analysis of the gut microbiomes of wild animals, we selected the Japanese macaques (Macaca fuscata yakui) on Yakushima Island. We tested different protocols for each stage of fecal sample processing: storage, DNA extraction, and choice of the sequencing region in the bacterial 16S rRNA gene. We also analyzed the gut microbiome of captive Japanese macaques as the control. The comparison of samples obtained from identical macaques but subjected to different protocols showed that the tested storage methods (RNAlater and lysis buffer) produced effectively the same composition of bacterial operational taxonomic units (OTUs) as the standard frozen storage method, although the relative abundance of each OTU was quantitatively affected. Taxonomic assignment of the detected bacterial groups was also significantly affected by the region being sequenced, indicating that sequencing regions and the corresponding polymerase chain reaction (PCR) primer pairs for the 16S rRNA gene should be carefully selected. This study improves the current standard methods for microbiome analysis in wild nonhuman primates. Japanese macaques were shown to be a suitable model for understanding microbiome adaptation to various environments.

Long-term follow-up study of borderline patients in Japan: a preliminary study.

To date, only few reports are available regarding the long-term outcome of borderline personality disorder (BPD) in Japan. We conducted a retrospective follow-up study on the long-term outcome and predictive factors of BPD in Japan. Of 72 patients who received treatment at Fukuoka University Hospital between 1973 and 1989 and met the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, criteria for BPD retrospectively, 19 patients (26.4%) were followed up. We evaluated global outcome at follow-up using the Global Assessment of Functioning Scale scored from a completed self-reported questionnaire. The mean Global Assessment of Functioning score was 60.7, which meant fair to good functioning. The suicide rate was 6.9% (5/72). Using a logistic regression model, overinvolvement in family relationships and the number of medical facilities where patient was previously treated predicted poor outcome. These results are similar to those reported in the United States and Canada, except for the result that Japanese patients with BPD are more likely to live with their original family at follow-up than American patients.