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Infertility is often cited as one of the causes of a declining birthrate, which has become a serious social problem in recent years. Processes by which motile sperm can be safely and easily sorted are therefore important for infertility treatment. Therefore, as a new sorting method, microfluidic sperm sorter using the microfluidic system has been developed. To improve more separation efficiency of this device, it is necessary to know the behaviors of motile sperm in the microchannel where the sperm undergo shear flow. The previous study implied the necessity of the modeling of motile sperm in the shear flow. In the present study, therefore, we experimentally investigated the behavior of the motile sperm in the Taylor-Couette flow using PTV (Particle Tracking Velocimetry) method. The experimental results showed that the ascent of the shear stress led to the increase in the sperm velocity, and the direction of the sperm velocity was opposite to that of the flow.
To estimate seismic damage of structures under strong motions is very important to know true safety of structures. However, we have to deal with very small failure probability issue to investigate quantitatively. If we use standard MCS (Monte Calro Simulation) to discuss failure probability, e.g., 1 × 10-6 order, since we have to execute nonlinear dynamic response analyses of approximate 107 times, it is not realistic. Recently, a subset simulation, which reduces the computation time by replacing small failure probability into the product of conditional failure probabilities, was proposed. In this study, the subset simulation is applied to estimate failure probability of an actual reinforced concrete building with 11 stories, and discuss the safety of the structure by checking with design criteria.
spin-magnetic moment of the electron is revisited. In the form of the
relativistic quantum mechanics, we calculate the magnetic moment of Dirac
electron with no orbital angular-momentum. It is inferred that obtained
magnetic moment may be the spin-magnetic moment, because it is never due to
orbital motion. A transition current flowing from a positive energy state to a
negative energy state in Dirac Sea is found. Application to the band structure
of semiconductor is suggested.