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シンポジウム 物心二元論の行方 : 心身問題の再検討 (Symposium: Dualism Revisited : A New Perspective on the Mind-Body Problem)

In 2011, the tsunami in Japan caused big damages in the coastal protection structures where a large number of armour units installed at the breakwaters were scattered. This work presents a numerical tool to simulate the behaviour of concrete armour units under wave action, which will help to design breakwaters that will be long-lasting and effective in protecting the coast. The Smoothed Particle Hydrodynamics (SPH) method is a meshless approach suitable for simulating multi-body and body-fluid interactions. SPH is based on a Lagrangian description of fluid motion in which continuum properties are reformulated in terms of smoothed quantities at discrete locations named "particles". SPH can be conveniently adopted to simulate free-surface flows and for capturing highly nonlinear behaviour of wave-structure interactions or fluid-driven objects. The SPH-based DualSPHysics code is coupled with Project Chrono library, a general-purpose simulation package for multi-body problems with support for large systems. Project Chrono solves the solid-solid interaction in terms of surface contacts. The movement of the Tetrapod units under solitary wave action is compared with physical model experiments carried out in a wave flume facility. The experimental campaign includes Tetrapods arranged in one row above a mound covered with PVC. The exact geometry of the Tetrapods, mass and material properties are defined in the simulations. For the block-block and block-mound interactions, the actual friction coefficient (obtained experimentally) is used by Project Chrono. The damage rate simulated in the numerical model, defined here as the percentage of Tetrapods that were moved and the mean displacements of the units, agree with the experimental results. Using DualSPHysics and Project Chrono, the hydrodynamic behaviour of the Tetrapods units against solitary waves is reproduced numerically, constituting a novel application of DualSPHysics to a real engineering problem.

In this study, we aimed to reproduce the hydrodynamic behavior of Tetrapod units against solitary waves using SPH methods. In particular, the DualSPHysics code was coupled with the multiphysics library Project Chrono. DualSPHysics solves the fluid-block interaction, while Project Chrono solves the block-block and block-mound interactions based on the contact and material properties of the block surface. In this work, modified dynamic boundary conditions and a new density-diffusion term based on the well-known delta-SPH formulation were applied to these simulations. The motion of the units during the simulation was compared with the physical model experiments. Prior to the comparison, it was confirmed that the propagation of the solitary wave was well reproduced by connecting the vertical 2-D analysis with the 3-D analysis using a multi-layered piston. The results showed that the displacements agreed well with an error of less than 6%. The results of the validation prove the capability of the DualSPHysics code to simulate challenging environments, not only solving the wavestructure interactions but also the objects collisions under the same numerical framework. This research was partially funded by Xunta de Galicia (Spain) under the project ED431C 2017/64 “Programa de Consolidación e Estructuración de Unidades de Investigación Competitivas (Grupos de Referencia)” cofunded by European Regional Development Fund (ERDF). Dr Domínguez acknowledges funding from Spanish government under the program “Juan de la Cierva incorporación 2017” (IJCI-2017-32592).

Aberrant female and male medusae of Turritopsis rubra and T. sp. (most frequently those with three oral lips and three gonads, but with normal four radial canals) were found (c 13% incidence in female of both species, n = 107, 85) in November, 2016 from Iwaki City, Fukushima Prefecture, Japan. In both species, parasitic trematoda was found; in T. sp. maximally eight individuals/normal medusa and five ones/aberrant medusa. Moreover, in the same place in Fukushima Prefecture and in the other place in Ibaragi Prefecture aberrant Turritopsis rubra mature medusae without oral lips or with 1, 2, 3, 5 oral lips, were also found (18.3 %, n = 142 in Otsu harbour in Ibaragi Prefecture) in October, 2017, 放射能の影響下にある福島県いわき市で2016年11月に同時採集したベニクラゲとニホンベニクラゲの成熟クラゲの雌雄において, 放射管は4本で正常だが口唇や生殖巣が三つの奇形などが出現した(2種の雌で各々約13%の奇形率, n= 107, 85). 2種とも吸虫類の寄生があり, ニホンベニクラゲの正常個体に最多で8個体. 奇形個体には5個体が見られた. 加えて, 福島県の同地点と茨城県の別地点で2017年10月に採集したベニクラゲの成熟クラゲで, 口唇が無いもの, 一つ, 二つ, 三つ. 五つ持つ個体等の奇形個体が出現したので(茨城県大津港で18.3%の奇形率, n= 142), それらの形態も記載した.

High rejuvenation rate was shown in Turritopsis sp. (Hydrozoa, Anthomedusae) collected from Tanabe Bay, Wakayama Prefecture, Japan in August 2017. Degeneration of medusae to dumplings was induced by isolation rearing, and succeeding transformation into polyps was controlled by seawater temperature., 生活環の逆戻り現象(『若返り』)が可能なニホンベニクラゲルTurritopsis sp. (ヒドロ虫綱, 花クラゲ目)における, 高い若返り率を報告する. 和歌山県田辺湾産ニホンベニクラゲ22個体の成熟個体を, ポリスチレン製細胞培養用マルチプレートを用いて止水飼育し, 2017年の8月から9月にかけて『若返り』に関する観察を記録した. 16個体については記録初期段階から一貫して水温25℃による飼育を行い, 6個体は水温4℃で一晩コールドショックを与えた後，水温25℃に戻して観察を続けた. この時, 水温25℃飼育の16個体の内, 4個体は同時にマルチプレートの1穴内で飼育したが, 他の12個体については, マルチプレートの1穴ごとに1個体ずつ隔離飼育した. その結果, 水温25℃飼育の16個体の内の12個体において, ポリプ幼体への『若返り』が確認された(75%). 一方, コールドショックを与えた6個体のポリプ幼体への若返り率は0%であった. また, マルチプレートで隔離飼育した12個体では, 11個体がポリプ幼体への『若返りを示した(92%).

In August and September in 2017, high rate of bleaching of corals and sea anemones observed in Tanabe Bay, Wakayama Prefecture, Japan owing to high water temperature more than 29℃ due to the recent global warming. However, recovery from bleaching in corals (17% from more than 70%, n = c 300) was recorded in October, 2017., 和歌山県田辺湾でイシサンゴ類やイソギンチャク類(刺胞動物)が、昨今の地球温暖化による高水温(29℃以上)により2017年の8-9月に高率の白化を起こしたので記録した。その後、10月に入ってイシサンゴ類はかなり回復した(7割以上から17%へ低下, n＝約300)。

16S mitocondrial gene sequence analysis using eight individuals prepared in the present study from three countries (Israel, Italy, Japan) revealed and confirmed that there are five species in Turritopsis in the world, and among which three species (Turritopsis rubra, T. sp. and T. dohrnii) are distributed in Japan and one of them (T. sp.) is endemic and distributed in central Japan. Among the species distributed in the Pacific Ocean, T. sp. is a sister species of the Chinese species (T. lata) that might be another endemic one, while T. rubra, that has a brooding habit, is more remote species than the Atlantic and the Mediterranean species (T. nutricula and T. dohrnii). The present analysis suggests that T. dohrnii is found in Israel in addition to Okinawa Island, Japan, possibly as another introduction example

One of the most evolutionary advanced species of the bivalve-inhabiting hydrozoans Eugymnanthea is recently found from Ongael Lake, Palau Islands, associated with Brachidontes sp. The morphology of mature male or spent male medusa is described, comparing with two known species of the genus, E. inquilina and E. japonica, and discussed on its taxonomic position since it shows intermediate character states between the two.

In Turritopsis rubra and T. sp., which are c. 10 mm and several mm in diameter and are distributed in northern and southern Japan, respectively, the same volume of their manubriums, c. 0.1 g in the total wet weight, were cut out under a stereomicroscope and major pigments were extracted with acetonitrile, then analyzed at 480 nm with high performance liquid chromatography (HPLC). As a result, two sharp peaks were found in T. rubra, of which manubrium is scarlet color, and these two kinds of pigment substances were comparatively analyzed with standard astaxanthin and canthaxanthin by HPLC, and proved to be these two chemical compounds. In contrast, in T. sp., of which manubrium is pale yellow, only astaxanthin was found. In relation to function of pigments and ecology of medusae, biological meaning of their differential coloration is discussed, and tentative suppositions, prevention of leak of bioluminescent baits within the manubrium and sun-screening effects, are proposed.