Katsunori Mizuno

The ultrasonic wave propagation of fast and slow waves was investigated in vitro in 35 cubic cancellous bone specimens extracted from human femoral heads. Measurements were performed in three orthogonal directions using home-made PVDF transducers excited by a single sinusoidal wave at 1 MHz. The apparent density of the specimens was measured. Two separated fast and slow waves were clearly observed in 16 specimens, mainly in the main load direction. The waveforms and the sound speeds of fast and

Ultrasonic waves in cancellous bone change dramatically depending on its structural complexity. One good example is the separation of an ultrasonic longitudinal wave into fast and slow waves during propagation. In this study, we examined fast wave propagation in cancellous bone obtained from the head of the bovine femur, taking the bone structure into consideration. We investigated the wave propagation perpendicular to the bone axis and found the two-wave phenomenon. By rotating the cylindrical

Protein tyrosine phosphatases (PTPs), together with protein tyrosine kinases (PTKs), are involved in the regulation of cell activation, growth, and differentiation. To further elucidate the fine tuning of cell growth and differentiation through tyrosine phosphorylation, we tried to isolate mouse receptor-type PTP (RPTP) cDNA clones by screening mouse brain cDNA libraries with mouse CD45 PTP domain probes under reduced-stringency conditions. Characterization of isolated cDNA clones for RPTP showe

Src homology region 2 (SH2) domain-containing phosphatase 1 (SHP-1; previously named HCP, PTP1C, SH-PTP1, and SHP) is a cytosolic protein tyrosine phosphatase that contains two SH2 domains. Recent data have demonstrated that the gene encoding SHP-1 is mutated in motheaten (mc) and viable motheaten (mc') mice resulting in autoimmune disease. More recently, SHP-1 has been shown to negatively regulate B cell antigen receptor (BCR)-initiated signaling. To elucidate potential mechanisms of SHP-1 acti

The influence of cancellous bone microstructure on the ultrasonic wave propagation of fast and slow waves was experimentally investigated. Four spherical cancellous bone specimens extracted from two bovine femora were prepared for the estimation of acoustical and structural anisotropies of cancellous bone. In vitro measurements were performed using a PVDF transducer (excited by a single sinusoidal wave at 1 MHz) by rotating the spherical specimens. In addition, the mean intercept length (MIL) an

Ultrasound propagation in cancellous bone (porous media) under the condition of closed pore boundaries was investigated. A cancellous bone and two plate-like cortical bones obtained from a racehorse were prepared. A water-immersion ultrasound technique in the MHz range and a three-dimensional elastic finite-difference time-domain (FDTD) method were used to investigate the waves. The experiments and simulations showed a clear separation of the incident longitudinal wave into fast and slow waves.

Over the last 3 decades, a large portion of coral cover has been lost around the globe. This significant decline necessitates a rapid assessment of coral reef health to enable more effective management. In this paper, we propose an efficient method for coral cover estimation and demonstrate its viability. A large-scale 3-D structure model, with resolutions in the x, y and z planes of 0.01 m, was successfully generated by means of a towed optical camera array system (Speedy Sea Scanner). The surv

Various methods have been developed and used for monitoring marine benthic habitats, such as coral reefs and seagrass meadows. However, the efficiency of general survey methods [e.g., line intercept transects and autonomous underwater vehicles (AUVs)] still is not high. In this article, we propose a practical coral-coverage estimation method combining an effective survey system [Speedy Sea Scanner (SSS)] and a deep-learning-based estimation method. The SSS is a towed-type system with six cameras

The two-wave phenomenon in a cancellous bone surrounded by a cortical bone was investigated using the specimens obtained from large mammals. Measurements were performed using laboratory-built poly(vinylidene fluoride) (PVDF) transducers excited by a one-cycle sinusoidal wave at 1 MHz. In addition to the experimental ultrasonic measurements, the finite-difference time-domain (FDTD) simulation was performed using the X-ray micro computed tomography (micro-CT) images (resolution: 48 µm) of the spec

In this study, we try for fish classification using high resolution acoustic video camera at 3.0 MHz center frequency (ARIS). Newly observation method with wide in vertical and narrow in horizontal beam (WVNHB) was proposed for getting high quality acoustic image of swimming fish, and tested an image processing algorithm basing on Normalized Cross Correlation (NCC) for fish classification. This high-frequency acoustic video camera was applied to fish classification for the first time. Using the

In this article, the detection of an object buried in marine sediments is investigated. Using the results from a series of experiments realized in a tank filled with water and calibrated glass beads, we evaluate the performances for a wide range of the value of the ratio kd of the grain size to the wavelength (k is the wave number and d is the grain diameter) of three types of prediction tools. The first two prediction tools are based on the definition of an equivalent model. The first tool is b

The deep ocean is Earth's largest habitable space inhabited by diverse benthic organisms. Infauna play crucial roles in shaping sedimentary structures, relocating organic matter, porewater chemistry, and hence biogeochemical cycles. However, the visualization and quantification of infauna in situ inside deep-sea sediment has been challenging, due to their sparse distribution and that deep-sea cameras do not visualize animals living below the sediment surface. Here, we newly developed a 3D acoust