Search

Seismic wave extractions have been performed using ambient noise records observed by distributed acoustic sensing (DAS) technology. Extractions of microseisms can be investigated at a local scale using such DAS records observed in the ocean. Here, we show Pand Scholte wave extractions from ambient seafloor noise observed by DAS along a submarine cable deployed off Cape Muroto in the Nankai subduction zone, Japan. The Pwaves can be observed at a frequency band of 0.1–0.3 Hz and up to a distance of 8 km. The distance at which the Pwaves can be observed is controlled by the Pincident angle and the DAS sensitivity to the observable apparent velocity. Effective extractions of Pand Scholte waves, corresponding to large intensity of wave‐wave interaction at the sea surface, are performed, indicating that the waves are originated from pressure field at the sea surface. The density of seismic observations on land is typically higher than that in the ocean. However, higher‐density observations in both land and ocean regions can be made using the recently developed distributed acoustic sensing (DAS). In this study, we focus on the waves persistently propagating through the Earth, which are excited by ocean swell and are called microseisms. Ocean swell at the sea surface primarily excites surface waves: however, Pand Swaves excited by ocean swell, especially during tropical storms, were observed on a global scale. Because this indicates that body waves may be locally excited by sea surface disturbances, we investigate the problem using DAS records. Our results show that large amplitudes of Pwaves occur when an atmospheric low pressure passes through Japan, and those amplitudes become weak when the wave‐wave interaction intensity at the ocean surface is weak. Although many previous studies at global or regional scales have indicated that microseisms are originated from fluid disturbances at the sea surface, the current study observed the excitation of Pand surface waves right beneath the sea surface disturbances. Pwaves were extracted from ambient seafloor noise records observed by distributed acoustic sensing (DAS) at a frequency band of 0.1–0.3 Hz and up to a distance of 8 kmExtraction of Pwaves depends on weather conditions, particularly for wave‐wave interaction intensity at the sea surfaceThe distance at which the Pwaves emerge is controlled by the Pincident angle and the DAS sensitivity to apparent velocities Pwaves were extracted from ambient seafloor noise records observed by distributed acoustic sensing (DAS) at a frequency band of 0.1–0.3 Hz and up to a distance of 8 km Extraction of Pwaves depends on weather conditions, particularly for wave‐wave interaction intensity at the sea surface The distance at which the Pwaves emerge is controlled by the Pincident angle and the DAS sensitivity to apparent velocities

Abstract Dynamic graciloplasty has recently been developed for reconstruction of anal function in patients who are fecally incontinent in preference to permanent abdominal colostomy. Since the muscular portion of gracilis is wrapped around the neoanus, the length of the gracilis arc influences the functional outcome of graciloplasty. Although dissection of the main pedicle (i.e. the main artery and vein) can facilitate gracilis to have enough muscle arc, it has been unclear whether there are any vessels proximal to the main pedicle or through the origin of the muscle which could support blood flow into the whole of gracilis. In this study, the vascular anatomy of gracilis in both legs of 26 Japanese cadavers was examined. All muscles had a main pedicle, mean maximum diameter 1.08 mm, entering at the proximal one-third of the muscle. However, only 18 muscles (34.6%) had an accessory artery in the proximal portion in addition to the main pedicle. Some arteries always exist at the origin of the muscle, having a mean maximum diameter of 0.34 mm, suggesting that they might be able to support the whole gracilis without supply from the main pedicle.

The spatial variation of azimuthal S‐wave phase velocity anisotropies caused by differential horizontal stress along the Nankai Trough was analyzed to understand the stress state of the overhung block of the forearc region, off Kii Peninsula, Japan. We conducted controlled‐source seismic surveys along the circumference of a 3 km radius circle centered at each seismometer of a cabled seafloor observatory installed in the Nankai subduction zone. We applied an anisotropy semblance method to estimate the orientation of fast and slow S‐wave velocities of shallow sediments and deep accretionary prism using the multi‐azimuth seismic dataset acquired at each seismometer location. The estimated orientations of fast S‐wave velocity are parallel to the convergent direction of the subducting place beneath the Kumano basin in the deeper accretionary prism while perpendicular to the convergent direction in the shallow sediments inside the Kumano basin. These fast S‐wave polarization orientations in shallow sediments show good agreement with horizontal maximum stress orientations estimated in situ borehole measurements in the observation area. We estimated the differential horizontal stress field in the Nankai Trough region from obtained S‐wave anisotropy using a simple crack model. Using this method, we first suggest the convergent‐parallel horizontal maximum compression in the deeper part of the accretionary prism above the locked portion. Assuming obtained S‐wave anisotropy is attributed to the tectonic loading by the subducting plate, these results suggest that the S‐wave azimuthal anisotropy measurements can be used to monitor the subsurface stress field as a function of time. In the Nankai Trough, Japan, giant megathrust earthquakes repeatedly occurred. Spatio‐temporal distribution of stress state in the subduction zone is a key parameter to understand the earthquake preparation and generation cycle. In the present study, we estimate the stress field along the Nankai Trough subduction zone from the S‐wave anisotropy analysis using active seismic data acquired by cabled seismic observatories deployed in the Nankai Trough. S‐wave anisotropy can be a proxy of the stress state if stress‐aligned microcracks are vertically distributed in the anisotropic medium. We estimate differential horizontal stress along the subduction zone using a new robust S‐wave analysis method and a simple stress‐induced microcrack model. The obtained orientations and amplitudes of the differential horizontal stress have good agreement with the existing results obtained by in‐situ borehole observations and other seismic surveys in the shallow sediment layer. In the deeper part, the accretionary prims layer above the plate interface, our results in the outer arc of the Kumano forearc basin indicate the plate convergence direction as orientation of maximum horizontal stress. The results are new insights, and can reflect the present stress state accumulating interseismic strain along the seismogenic fault. S‐wave anisotropy is obtained from multi‐azimuth seismic dataset observed by cabled seismometers deployed in the Nankai Trough, JapanDifferential horizontal stress field in the Nankai Trough region is estimated from obtained S‐wave anisotropy using a simple crack modelThe estimated horizontal stress field can reflect the present stress state accumulating interseismic strain along the seismogenic fault S‐wave anisotropy is obtained from multi‐azimuth seismic dataset observed by cabled seismometers deployed in the Nankai Trough, Japan Differential horizontal stress field in the Nankai Trough region is estimated from obtained S‐wave anisotropy using a simple crack model The estimated horizontal stress field can reflect the present stress state accumulating interseismic strain along the seismogenic fault

Japan is one of the countries which have been producing and broadcasting a large number of programmes for children, both educational and entertainment, and both types of programme have been widely watched by children in other countries in recent years. This article introduces the characteristics of Japanese children's television viewing and some examples of studies on the development of new television programmes for young children and then discusses the possibility of the development of international television programmes for children.

The emission angle distribution of projectile fragments (PFs) and the temperature of PF emission sources for fragmentation of 56Feon polyethylene, carbon, and aluminum targets at the highest energy of 497 A MeV are investigated on the basis of corrected data, using a CR-39 plastic nuclear track detector. It is found that the average emission angle of PFs increases with the decrease in PF charge for the same target, and no obvious dependence of angular distribution on the mass of the target nucleus is found for the same PF. The cumulative squared transverse momentum distribution of PFs can be well represented by a single Rayleigh distribution. The temperature of PF emission sources is extracted from the distribution, and it is about 1.0–8.0 MeV and does not depend on the mass of the target for PFs with charges of 9≤Z≤25.

The case of a 16-year-old boy is reported who underwent surgery for the excision of an Askin tumor and has subsequently undergone six excisions of local Askin tumor recurrences, with follow-up postoperative chemo- and radiotherapy over a 7-year period. The patient continues to survive. As far as can be determined, this patient appears to be the first reported case of long-term survival after repeated resections of local Askin tumor recurrences. It thus may be that postoperative chemo- and radiotherapy after repeated excisions of these local Askin tumor recurrences plays a role in prolonging survival.

J Thorac Cardiovasc Surg 1998;116:649-51