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This study used a dental model scanner and best-fit alignment to analyze the deformation patterns of stabilized occlusal appliances (OcAs) used to treat sleep bruxism when stored in wet or dry conditions. Eight OcAs were prepared using polymethyl methacrylate, stored in water at room temperature for 4 weeks (wet storage), and then in air for 4 weeks (dry storage). After being stored in water for one month for hydration, they were 3D-scanned and digitized on days 0, 28, and 56. 3D-deformation patterns were obtained by comparing the storage-D group data using a best-fit alignment program that aligns the nearest points of the corresponding images in a virtual space and calculates the difference between the two images. The maximum deviation and deformed area in the ± direction, and the volume of the wet (W) and the dry (D) condition groups were compared using Wilcoxon's signed rank test. OcA showed no obvious deformities in the W group at 4 weeks. However, in the D Group, a typical deformation pattern was detected at 4 weeks, with the posterior margin of the molars shrinking anteriorly, the palatal side of the molars lifted, and the buccal side retracted inward. The Ⅾ group was significantly larger than the W groups in terms of maximum deviation in the ± direction, deformed area, and volume. After 4 weeks of storage under dry conditions, OcA showed a typical deformation pattern of shrinkage toward the center, with in-center lifting toward the palatal side. Significantly greater surface deviations, deformation areas, and deformation volumes were observed under dry conditions than in wet conditions.

Chloroplast development adapts to the environment for performing suitable photosynthesis. Brassinosteroids (BRs), plant steroid hormones, have crucial effects on not only plant growth but also chloroplast development. However, the detailed molecular mechanisms of BR signaling in chloroplast development remain unclear. Here, we identify a regulator of chloroplast development, BPG4, involved in light and BR signaling. BPG4 interacts with GOLDEN2-LIKE (GLK) transcription factors that promote the expression of photosynthesis-associated nuclear genes ( PhANGs ), and suppresses their activities, thereby causing a decrease in the amounts of chlorophylls and the size of light-harvesting complexes. BPG4 expression is induced by BR deficiency and light, and is regulated by the circadian rhythm. BPG4 deficiency causes increased reactive oxygen species (ROS) generation and damage to photosynthetic activity under excessive high-light conditions. Our findings suggest that BPG4 acts as a chloroplast homeostasis factor by fine-tuning the expression of PhANGs , optimizing chloroplast development, and avoiding ROS generation. The authors identify BPG4, a novel regulator of chloroplast development. BPG4 directly suppresses transcriptional activity of GLK to fine-tune photosynthesis associated nuclear gene expression, and regulates chloroplast development and homeostasis.

Although nation-wide assessments on the grassland soil carbon storage have been conducted in Japan, the uncertainty of the estimation accuracy remains with its local variability. In the present study, using geostatistical approach, we assessed the spatial variability and distribution pattern of organic carbon (OC) and estimated its total stock in the surface soils (0–5 cm) over Mt. Wakakusa grassland (30.2 ha) of Central Japan. The exploratory statistics indicated that the surface soils had 1.88 ± 0.28 kg C m−2 of soil OC density on average (n = 147) with a moderate variability (CV = 18.8%), while the geostatistical analysis unveiled that its semivariogram was well fitted by a spherical model (R2 = 0.93, RSS = 1.15E−05) and had a strong spatial dependency (nugget–sill ratio = 0.31). Based on these results, we constructed an interpolated map and estimated total OC stock to 552 Mg C in the surface soil of Mt. Wakakusa grassland.

To provide spatial information on soil resources for sustainable land management in the Mt. Wakakusa Grassland of central-western Japan, we investigated the spatial variation and distribution of selected micronutrients, i.e., Mehlich 3 extractable Fe, Mn, Cu, and Zn (referred as M3-Fe, M3-Mn, M3-Cu, and M3-Zn, respectively), in surface soils (0–5 cm in depth) of the grassland. All micronutrients showed intermediate variability, with coefficients of variation ranging from 26.9 to 48.9%. The M3-Fe (144.0 ± 32.9 mg kg−1) and M3-Mn (204.8 ± 91.3 mg kg−1) contents were relatively high compared with the optimal level exhibited by M3-Cu (1.8 ± 0.5 mg kg−1) and the low level given by M3-Zn (7.8 ± 2.2 mg kg−1). The availability of these micronutrients, except for M3-Zn, showed more significant correlations with the soil mineral phase than with the soil pH and organic matter. Variogram analysis reveals a moderately weak spatial dependency [nugget-to-sill (N/S) ratio = 0.67] for the M3-Zn, while the other micronutrients (M3-Fe, M3-Mn, and M3-Cu) exhibit moderately strong to strong spatial dependencies (N/S ratio = 0.21–0.50). Interpolation maps created in this study demonstrate locations with toxic levels of M3-Fe and M3-Mn and those deficient in M3-Mn and M3-Cu in the study site. Based on these results, a site-specific soil management scheme is recommended in the Mt. Wakakusa Grassland.

ObjectivesSleep bruxism (SB) is associated with physiological activities including sympathetic autonomic system dominance and sleep micro-arousal. While oral appliances (OA) are used to prevent SB harmful effects, the influence of OAs physiological mechanisms during sleep is unknown. The aim of this study is to assess whether heart rate variability (HRV) changes, as a marker of autonomic nervous system activity, would be associated with the OA mechanism of action on SB using occlusal splint (OS) and mandibular advancement splint (MAS).Materials and methodsA retrospective analysis, from data previously collected in 21 participants with SB (25.6 ± 4.5 years) with polysomnographic recordings, was done. HRV data were compared between a reference night (no-device) and ones during which OS or MAS was used in a crossover study design. Rhythmic masticatory muscle activity (RMMA) index was compared between nights. HRV was evaluated using autoregressive model analysis for three sections: baseline (distance from RMMA), immediately before, and after RMMA period.ResultsA significant reduction in RMMA index, when wearing OA during sleep, was observed (P < 0.01), but was not associated with HRV parameters change. HRV significantly changed after RMMA onset for nights with OA during non-REM sleep in comparison with baseline (P < 0.02).ConclusionsThe usage of OAs for SB participants reduced RMMA, but most likely independently of changes in HRV linked to the mechanism associated with SB genesis.Clinical relevanceWearing OA seems to reduce grinding noise and protect from dental injuries but does not seem to influence SB genesis.

Hydrothermal fluid migration and supercritical phase transitions around the brittle–ductile transition are key to understanding volcanic activity and geothermal energy, but it remains challenging due to limited subsurface imaging. Here we conducted active-source seismic surveys at Kuju volcano, Japan, applying extended common-reflection-surface analysis to image magma-related and hydrothermal structures. We further estimated earthquake hypocenters, focal mechanisms, and seismic velocity. A continuous horizontal reflector could indicate a low-permeability seal confining supercritical fluids, while a low-amplitude reflection zone reveals fractures disrupting the seal. This permeable window, located at the magma margin, coincides with earthquake clusters of various focal mechanisms, suggesting upward fluid migration. A plume-shaped zone with low P-wave and S-wave velocity ratio (Vp/Vs) above the permeable window indicates thermally-altered formations and gas release from phase transitions. These results provide 3D visualization of the interplay among trapped supercritical fluid, its migration through permeable window, and related seismicity near the brittle-ductile transition. The Kuju volcanic area’s shallow magma margin features a low-amplitude reflection zone that allows pressurized fluids to migrate upward, causing diverse earthquake clusters with complex mechanisms, according to analysis of magma-related and hydrothermal structures in the Kuju volcanic area in Japan.

The Hokkaido Eastern Iburi Earthquake (M = 6.7) occurred on Sep. 6, 2018 in the southern part of Central Hokkaido, Japan. Since Paleogene, this region has experienced the dextral oblique transpression between the Eurasia and North American (Okhotsk) Plates and the subsequent collision between the Northeast Japan Arc and the Kuril Arc due to the oblique subduction of the Pacific Plate. This earthquake occurred beneath the foreland fold-and-thrust belt of the Hidaka Collision zone developed by the collision process, and is characterized by its deep focal depth (~ 37 km) and complicated rupture process. The reanalyses of controlled source seismic data collected in the 1998–2000 Hokkaido Transect Project revealed the detailed structure beneath the fold-and-thrust belt, and its relationship with the aftershock activity of this earthquake. Our reflection processing using the CRS/MDRS stacking method imaged for the first time the lower crust and uppermost mantle structures of the Northeast Japan Arc underthrust beneath a thick (~ 5–10 km) sedimentary package of the fold-and-thrust belt. Based on the analysis of the refraction/wide-angle reflection data, the total thickness of this Northeast Japan Arc crust is only 16–22 km. The Moho is at depths of 26–28 km in the source region of the Hokkaido Eastern Iburi Earthquake. Our hypocenter determination using a 3D structure model shows that most of the aftershocks are distributed in a depth range of 7–45 km with steep geometry facing to the east. The seismic activity is quite low within the thick sediments of the fold–thrust belt, from which we find no indication on the relationship of this event with the shallow (< 10–15 km) and rather flat active faults developed in the fold-and-thrust belt. On the other hand, a number of aftershocks are distributed below the Moho. This high activity may be caused by the cold crust delaminated from the Kuril Arc side by the arc–arc collision, which prevents the thermal circulation and cools the forearc uppermost mantle to generate an environment more favorable for brittle fracture.

Background: The sphenoid sinus (SS) is located close to vital structures, such as the pituitary gland, and it has significant clinical relevance. This study aimed to clarify the growth pattern of the SS in Japanese children using three-dimensional computed tomography (CT). Methods: Seventy-eight participants with congenital, acquired, or external auditory canal cholesteatoma were recruited and underwent CT more than twice during their treatment. Using the volume-rendered images, the size and volume of the SS were measured. Furthermore, on the scout image, the morphological measurements of the cranial base were determined. Results: The size and volume of the SS increased with age, and peaked at the mean age of 15 years. For males, the volume of the SS was smaller than that of females aged <5 years. The growth rate of the SS was significantly higher in males than in females. The maximum growth rate was detected at the age of 12 years for males and 10 years for females. For females, the increase in the length of the anterior cranial base ceased at approximately 10 years of age and remained constant thereafter. In contrast, for males, the length of the anterior cranial base increased gradually until 15 years of age. Conclusions: Considering the similarity of the periods between the adolescent growth spurt and the maximum growth rate of the SS, changes in the size of the SS may be used as an indicator of the physical growth spurt.

The adenoid (Ad) and tonsil (Ts), located in the upper airway, play an important role in immunological protection. These lymphoid tissues grow rapidly, reach a peak of growth at the age of 6–8 years, and decrease in their size thereafter. However, little information is available on the longitudinal growth patterns of Ad and Ts in the general population. This study aimed to evaluate the individual growth of Ad and Ts during childhood using lateral cephalograms taken longitudinally from the same individuals at the ages of 8–12 years. Our results showed that the cross-sectional areas of the Ad, nasopharynx (Np), and oropharynx (Op) significantly increased with age while small changes in the size of Ts were present throughout the study period. In addition, the values of Ad/Np and Ts/Op decreased significantly with age in the elementary school. Furthermore, there was a strong and significant correlation between the Ad/Np ratio and upper airway resistance, indicating the narrowest distance in the upper airway. In conclusion, the airway occupation in Np and Op increased with age due to the increase in the sizes of Np and Op but not the decrease in the sizes of Ad and Ts.

In the original publication of this article (Iwasaki et al. 2019), the author name ‘Matsubara Makoto’ in author list is not correct. The correct name should be ‘Makoto Matsubara’.