Nonreciprocal Phonon Propagation in a Metallic Chiral Magnet.

The phonon magnetochiral effect (MChE) is the nonreciprocal acoustic and thermal transports of phonons caused by the simultaneous breaking of the mirror and time-reversal symmetries. So far, the phonon MChE has been observed only in a ferrimagnetic insulator Cu_{2}OSeO_{3}, where the nonreciprocal response disappears above the Curie temperature of 58 K. Here, we study the nonreciprocal acoustic properties of a room-temperature ferromagnet Co_{9}Zn_{9}Mn_{2} for unveiling the phonon MChE close to room temperature. Surprisingly, the nonreciprocity in this metallic compound is enhanced at higher temperatures and observed up to 250 K. This clear contrast between insulating Cu_{2}OSeO_{3} and metallic Co_{9}Zn_{9}Mn_{2} suggests that metallic magnets have a mechanism to enhance the nonreciprocity at higher temperatures. From the ultrasound and microwave-spectroscopy experiments, we conclude that the magnitude of the phonon MChE of Co_{9}Zn_{9}Mn_{2} mostly depends on the Gilbert damping, which increases at low temperatures and hinders the magnon-phonon hybridization. Our results suggest that the phonon nonreciprocity could be further enhanced by engineering the magnon band of materials.

Search for the Pair Production of Dark Particles X with K_{L}

We present the first search for the pair production of dark particles X via K_{L}^{0}→XX with X decaying into two photons using the data collected by the KOTO experiment. No signal was observed in the mass range of 40-110 MeV/c^{2} and 210-240 MeV/c^{2}. This sets upper limits on the branching fractions as B(K_{L}^{0}→XX)<(1-4)×10^{-7} and B(K_{L}^{0}→XX)<(1-2)×10^{-6} at the 90% confidence level for the two mass regions, respectively.

Magnetically Hidden State on the Ground Floor of the Magnetic Devil's Staircase.

We investigated the low-temperature and high-field thermodynamic and ultrasonic properties of SrCu_{2}(BO_{3})_{2}, which exhibits various plateaux in its magnetization curve above 27 T, called a magnetic Devil's staircase. The results of the present study confirm that magnetic crystallization, the first step of the staircase, occurs above 27 T as a first-order transition accompanied by a sharp singularity in heat capacity C_{p} and a kink in the elastic constant. In addition, we observe a thermodynamic anomaly at lower fields around 26 T, which has not been previously detected by any magnetic probes. At low temperatures, this magnetically hidden state has a large entropy and does not exhibit Schottky-type gapped behavior, which suggests the existence of low-energy collective excitations. Based on our observations and theoretical predictions, we propose that magnetic quadrupoles form a spin-nematic state around 26 T as a hidden state on the ground floor of the magnetic Devil's staircase.

Study of the K_{L}→π

The rare decay K_{L}→π^{0}νν[over ¯] was studied with the dataset taken at the J-PARC KOTO experiment in 2016, 2017, and 2018. With a single event sensitivity of (7.20±0.05_{stat}±0.66_{syst})×10^{-10}, three candidate events were observed in the signal region. After unveiling them, contaminations from K^{±} and scattered K_{L} decays were studied, and the total number of background events was estimated to be 1.22±0.26. We conclude that the number of observed events is statistically consistent with the background expectation. For this dataset, we set an upper limit of 4.9×10^{-9} on the branching fraction of K_{L}→π^{0}νν[over ¯] at the 90% confidence level.

Phonon Magnetochiral Effect.

The magnetochiral effect (MCE) of phonons, a nonreciprocal acoustic propagation arising due to symmetry principles, is demonstrated in the chiral-lattice ferrimagnet Cu_{2}OSeO_{3}. Our high-resolution ultrasound experiments reveal that the sound velocity differs for parallel and antiparallel propagation with respect to the external magnetic field. The sign of the nonreciprocity depends on the chirality of the crystal in accordance with the selection rule of the MCE. The nonreciprocity is enhanced below the magnetic ordering temperature and at higher ultrasound frequencies, which is quantitatively explained by a proposed magnon-phonon hybridization mechanism.

Search for K_{L}→π

A search for the rare decay K_{L}→π^{0}νν[over ¯] was performed. With the data collected in 2015, corresponding to 2.2×10^{19} protons on target, a single event sensitivity of (1.30±0.01_{stat}±0.14_{syst})×10^{-9} was achieved and no candidate events were observed. We set an upper limit of 3.0×10^{-9} for the branching fraction of K_{L}→π^{0}νν[over ¯] at the 90% confidence level (C.L.), which improved the previous limit by almost an order of magnitude. An upper limit for K_{L}→π^{0}X^{0} was also set as 2.4×10^{-9} at the 90% C.L., where X^{0} is an invisible boson with a mass of 135 MeV/c^{2}.

Diagnostic features of acquired dermal melanocytosis of the face and extremities.

Acquired dermal melanocytosis of the face and extremities (ADMFE) is an unusual form of acquired dermal melanocytosis (ADM). In this paper, we report a case of ADMFE and review the published literature. Our review highlights several clinical differences between ADMFE and ADM: (i) more frequent involvement of the nasal alae in ADMFE than in ADM, (ii) less frequent involvement of the cheeks in ADMFE than in ADM, (iii) limbs affected in all cases of ADMFE but in few cases of ADM, and (iv) frequent involvement of conjunctiva and/or gingiva in ADMFE but very rare involvement in ADM. These findings strongly support the hypothesis that ADMFE is clinically distinct from the classic form of ADM, and gaining an understanding of its phenotype will enable accurate diagnosis and early intervention by Q-switched laser therapy, which should benefit those patients with disease-related cosmetic issues.

Eosinophilic annular erythema is clinically characterized by central pigmentation reflecting basal melanosis: a clinicopathological study of 10 cases.

BACKGROUND: Eosinophilic annular erythema (EAE) has been proposed as a clinical entity to describe annular skin lesions associated with tissue eosinophilia. However, systematic investigations on the histopathology of EAE have not been performed, and useful histopathological findings for diagnosis of EAE remain unknown. OBJECTIVE: The aim of this study was to investigate the clinicopathological features of EAE. METHODS: We retrospectively studied 10 patients at our hospital during a 5-year span who clinically showed annular or figurate lesions and histopathologically exhibited eosinophilic infiltration in the dermis. RESULTS: Nine of the 10 cases had annular lesions with pigmentation on the interior side. Blood eosinophilia was found in only one patient. Histopathologically, basal melanosis was observed in nine cases. Infiltration of eosinophils was confined to the dermis in nine cases. Patients treated with systemic corticosteroid tended to show less recurrence than those treated with topical corticosteroid. LIMITATIONS: The main limitation of our study is the small number of patients. CONCLUSION: Skin biopsy should be performed when EAE is suspected, even in cases without blood eosinophilia. Basal melanosis and tissue eosinophilia confined to the dermis suggest the diagnosis of EAE. We recommend topical corticosteroids as the initial treatment for EAE.

Compound heterozygotes for filaggrin gene mutations do not always show severe atopic dermatitis.

BACKGROUND: Mutations in FLG, which encodes profilaggrin, cause ichthyosis vulgaris (IV) and are an important predisposing factor for atopic dermatitis (AD). IV shows autosomal hemidominant (semidominant) inheritance, and patients with bi-allelic FLG mutations tend to have severe IV phenotypes. However, the effect of bi-allelic FLG mutations on AD incidence and severity remains a subject of controversy. OBJECTIVE: In this study, we studied individuals with bi-allelic null FLG mutations to elucidate the effect of bi-allelic FLG mutations on AD incidence and severity. METHODS: Six individuals with bi-allelic FLG null mutations from three families of IV/AD were investigated. We report the detailed clinical features of the individuals. The phenotype was confirmed by the clinical examinations and the severity of IV and AD was scored using ichthyosis score and Eczema Area and Severity Index (EASI). RESULT: It was found that five of the six patients had severe IV, and the remaining patient showed moderate IV. Two of the six had moderate AD and three of the six had mild AD. The remaining patient had no AD. CONCLUSION: Our results suggest that individuals with bi-allelic FLG mutations do not always have severe AD and confirm that not all individuals with bi-allelic FLG mutations have AD.

Relationships between transepidermal water loss, cutaneous microcirculatory function and autonomic nervous activity.

OBJECTIVE: Several studies have shown that a deterioration of skin properties, an impaired cutaneous microcirculatory function and an imbalance of autonomic nervous activity are observed in smokers and in patients with diabetes mellitus or Raynaud's phenomenon. These observations suggest that skin properties are associated with cutaneous microcirculatory function and autonomic nervous activity in pathological conditions. However, there is no published evidence to support the concept that these two functions have any relationship with skin properties even in healthy subjects. To investigate the hypothesis that these properties are related, we conducted a survey of healthy adult subjects to investigate the relationships between cutaneous microcirculatory function and autonomic nervous activity and skin properties. METHODS: The hydration of the stratum corneum and transepidermal water loss (TEWL) were investigated as skin properties, and the responsiveness of skin blood flow (SkBF) to local warming was examined as an index of cutaneous microcirculatory function in 19 healthy adult male subjects. Electrocardiograms were monitored for 24 h and heart rate variability was analysed considering low-frequency power (LF: 0.04-0.15 Hz), high-frequency power (HF: 0.15-0.40 Hz) and a ratio of low- to high-frequency power (LF/HF) as indices of autonomic nervous activity; HF is an index of parasympathetic activity, whereas LF/HF is an index of sympathovagal balance. The relationships between those indices were then analysed. RESULTS: A moderate negative correlation was found between TEWL and the relative maximum rate of increases in the responsiveness of SkBF on local warming. A moderate positive and a moderate negative correlation were observed between TEWL and LF/HF or HF, respectively. Moreover, a moderate negative and a moderate positive correlation were shown between the responsiveness of SkBF and LF/HF or HF, respectively. The hydration of the stratum corneum showed no correlations with any indices of microcirculation or autonomic nervous activity. CONCLUSION: These results indicate that skin barrier function, cutaneous microcirculatory function and autonomic nervous activity are mutually associated in healthy adults.

The evolutionary 'tinkering' of MscS-like channels: generation of structural and functional diversity.

The mechanosensitive channel of small conductance (MscS)-like channel superfamily is present in cell-walled organisms throughout all domains of life (Bacteria, Archaea and Eukarya). In bacteria, members of this channel family play an integral role in the protection of cells against acute downward shifts in environmental osmolarity. In this review, we discuss how evolutionary 'tinkering' has taken MscS-like channels from their currently accepted physiological function in bacterial osmoregulation to potential roles in processes as diverse as amino acid efflux, Ca(2+) regulation and cell division. We also illustrate how this structurally and functionally diverse family of channels represents an essential industrial component in the production of monosodium glutamate, an attractive antibiotic target and a rich source of membrane proteins for the studies of molecular evolution.

One-Way Transparency of Light in Multiferroic CuB(2)O(4).

We experimentally demonstrate one-way transparency of light in multiferroic CuB(2)O(4). The material is rendered transparent for light propagating in one direction, while opaque for light propagating in the opposite direction. The novel transparency results from a destructive interference of the electric dipole and magnetic dipole transitions. The realization of the effect has been accomplished by the application of a high magnetic field and the proper selection of the propagation direction of light in agreement with our quantum mechanical formulation of nonreciprocal directional dichroism.