Vortex phase matching of a self-propelled model of fish with autonomous fin motion

It has been a long-standing problem how schooling fish optimize their motion by exploiting the vortices shed by the others. A recent experimental study showed that a pair of fish reduce energy consumption by matching the phases of their tailbeat according to their distance. In order to elucidate the dynamical mechanism by which fish control the motion of caudal fins via vortex-mediated hydrodynamic interactions, we introduce a new model of a self-propelled swimmer with an active flapping plate. The model incorporates the role of the central pattern generator network that generates rhythmic but noisy activity of the caudal muscle, in addition to hydrodynamic and elastic torques on the fin. For a solitary fish, the model reproduces a linear relation between the swimming speed and tailbeat frequency, as well as the distributions of the speed, tailbeat amplitude, and frequency. For a pair of fish, both the distribution function and energy dissipation rate exhibit periodic patterns as functions of the front-back distance and phase difference of the flapping motion. We show that a pair of fish spontaneously adjust their distance and phase difference via hydrodynamic interaction to reduce energy consumption.Comment: 18 pages, 11 figure

A Study on Failure Mechanism of Embankment Dams for Irrigation Damaged by the 1995 Hyogoken-Nanbu Earthquake

The objects of this investigation are to examine the following mechanism of embankment dams for irrigation damaged by the 1995 Hyogoken-Nanbu Earthquake; 1) the mechanism and process of collapse for the Idenoshiri-Ike embankment dam using the effective stress earthquake response analysis; 2) the mechanism of upper slope failure for the Sugatadani-Ike embankment dam using the total stress earthquake response analysis as well as the slope stability analysis with seismic intensity. As a result, the following conclusions are obtained for each objects; 1) the mechanism and process of collapse due to liquefaction can be analyzed that the liquefied areas initially occurred at the toes of upper and lower slopes are extended and connected to make flow downward the volume of embankment and that the result of this analysis is consistent with the real damaged situation; 2) the mechanism of upstream slope failure can be explained only with considering the increase of excess pore pressure in the upstream slope, not extending complete liquefaction, using the both analyses

Effect of serum fractions obtained from cancer patients by double filtration plasmapheresis combined with natural tumor necrosis factors and cyclophosphamide on murine pulmonary metastases.

We investigated the effects of fractionated sera obtained from cancer patients by double filtration plasmapheresis (DFPP) plus antitumor agents on murine pulmonary metastasis. Fractions of the sera, in combination with natural human tumor necrosis factors (nTNF) and cyclophosphamide (Cy), were systemically administered to Lewis lung carcinoma-bearing mice. When the second filtrate (a plasma fraction containing substances composed of smaller molecular weight compounds) combined with low-dose nTNF (1,000 U/kg) and Cy (250 micrograms/kg) was administered to the mice, the degree of metastasis was significantly suppressed compared with the control group (p less than 0.01). In contrast, the discarded fluid (a plasma fraction containing larger molecular weight compounds) combined with the same doses of nTNF and Cy caused little inhibition of metastasis. Also, the discarded fluid significantly suppressed natural killer activity compared with normal sera (p less than 0.01). The results suggested that DFPP combined with nTNF and Cy is an efficient procedure to remove immunosuppressive factors from the sera of cancer-bearing hosts, to enhance the host antitumor immunity, and to suppress tumor proliferation.</p

Improving bonding strength by non-thermal atmospheric pressure plasma-assisted technology for A5052/PEEK direct joining

The direct bonding of A5052 aluminum (Al) alloy to the engineering polymer poly(ether ether ketone) (PEEK) using an atmospheric pressure plasma-assisted process was demonstrated. The effect of plasma irradiation on the bonding surface of metal resin on the bonding strength following thermal press fitting method was investigated. Specimens bonded by plasma irradiation on the PEEK surface only showed a high tensile shear stress of 15.5 MPa. With increasing plasma irradiation time, the bond strength of the samples bonded to the PEEK surface by plasma irradiation increased. The increase in the bond strength between metals and polymers following direct bonding is caused by the addition of oxygen functional groups on the polymer. In contrast, specimens in which only the Al was exposed to the plasma showed a decrease in bond strength compared with unirradiated samples. This reduction in bond strength is attributed to the forming magnesium oxide, which forms in the early stages of participation due to plasma irradiation.The version of record of this article, first published in International Journal of Advanced Manufacturing Technology, is available online at Publisher’s website: https://doi.org/10.1007/s00170-023-12747-

Damages to the brick buildings at Tokyo Imperial University

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Retrospective Comparison of Non-Skin-Sparing Mastectomy and Skin-Sparing Mastectomy with Immediate Breast Reconstruction

Background. We compared Skin-sparing mastectomy (SSM) with immediate breast reconstruction and Non-skin-sparing mastectomy (NSSM), various types of incision in SSM. Method. Records of 202 consecutive breast cancer patients were reviewed retrospectively. Also in the SSM, three types of skin incision were used. Type A was a periareolar incision with a lateral extension, type B was a periareolar incision and axillary incision, and type C included straight incisions, a small elliptical incision (base line of nipple) within areolar complex and axillary incision. Results. Seventy-three SSMs and 129 NSSMs were performed. The mean follow-up was 30.0 (SSM) and 41.1 (NSSM) months. Respective values for the two groups were: mean age 47.0 and 57; seven-year cumulative local disease-free survival 92.1% and 95.2%; post operative skin necrosis 4.1% and 3.1%. In the SSM, average areolar diameter in type A & B was 35.4 mm, 43.0 mm in type C and postoperative nipple-areolar plasty was performed 61% in type A & B, 17% in type C, respectively. Conclusion. SSM for early breast cancer is associated with low morbidity and oncological safety that are as good as those of NSSM. Also in SSM, Type C is far superior as regards cost and cosmetic outcomes