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11.
The growth of thermal-chemical instability in a pre-galactic medium is followed by numerical simulation of gas dynamics. Results show that a primordial gas cloud breaks into self-gravitating subcondensations with the mass of normal stars.Paper presented at the IAU Third Asian-Pacific Regional Meeting, held in Kyoto, Japan, between 30 September–6 October, 1984. 相似文献
12.
There is the natural habitat of polyps of the common jellyfish Aurelia aurita in the Taniyama area, Kagoshima Bay. We examined the attachment substrata, density, colony structure and strobilation of
the polyps. The polyps were observed only on the horizontal undersurface of floating piers. They attached specifically to
Mytilus shells, solitary ascidians, calcareous polychaete tubes, muddy amphipod tubes and the gap space that fouling animals peeled
off the substrata. The polyp colonies were distributed in patches. Spatial distribution patterns of the polyps within their
colonies were uniform. Strobilation occurred during late December to March, when water temperatures were 16–17°C, and a large
number of ephyrae were released. An increase in man-made structures such as floating piers in coastal areas may lead to bloomings
of Aurelia aurita medusae.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
13.
The commercially important sergestid shrimp,Sergia lucens (Hansen), has long been considered an endemic species of Japan because it had been found only in Suruga Bay and neighbouring waters. Recently, however, a considerable amount of a similar shrimp was caught by trawl nets off Tung-kang, southwestern Taiwan. This shrimp is distributed at depths of 100–300 m on the continental slope, around a deep submarine canyon adjacent to the mouth of the Kao-ping River. A morphological comparison with specimens from Suruga Bay reveals that the shrimp is identical toS. lucens. However, a slight difference in the patterns of water-soluble proteins was observed in a thin layer isoelectrophoretic examination. A difference was also observed in the spawning season of the two populations, indicating sexual and geographic isolation. Considering the distribution and phylogeny of the family Sergestidae, based on a possible evolutionary development from a benthic neritic organism to a pelagic oceanic one along the generaSicyonella-Sergestes-Sergia, it is assumed thatS. lucens entered a lower epipelagic habitat in the coastal waters from the warm oceanic mesopelagic habitat of the original stock. A hypothesis is proposed that speciation ofS. lucens from the original stock occurred when it was trapped in a semi-enclosed inlet (the paleo-East China Sea Gulf) that existed at the present Okinawa Trough during the late Pliocene to early Pleistocene. The inlet was deep, but had a neritic environment due to drainage from ancient large river systems, including the paleo-Yangtze River. The species expanded its distribution to the neighbouring waters during the warm interglacial period. However, a rapid rise in sea level after 14,000 years significantly changed the environmental conditions in the distributional area and the species could not expand into a neritic environment, which was too shallow for survival. Accordingly,S. lucens populations remained only in Suruga Bay and Tung-kang waters, where the environment has remained stable for the last 17,000 years or more. The two areas have the following common characteristics:
- A large amount of fresh water is discharged into the deep submarine canyon adjacent to the river mouth.
- The northeastern part is surrounded by land so that a direct inflow of boreal water into the environment is blocked.
- Warm Kuroshio extension water intrudes and mixes with water from the rivers, and for Suruga Bay there is a current system that keeps distribution of the eggs and larvae restricted to the local habitats.
14.
Makoto Kashiwai 《Journal of Oceanography》1984,40(2):135-147
The principal character of the tidal exchange process is neither diffusion nor advection, but a third category of transport,
“Massenaustausch”, which appears in the space/time averaged transport. The exchange process can be divided into four fluxes:
the flux of standing eddies, the flux of tidal exchange, the flux of tidal eddies and the flux of local eddies. The results
of observations at the entrance channel of Kumihama-Bay show a typical example of transport dominated by tidal exchange.
The tidal exchange ratio defined by Parkeret al. (1972) applies to the process of exchange between the outflowing watermass and the surrounding watermass outside of the bay
mouth, but this should also be considered as being coupled with the ratio for the process of exchange between the inflowing
watermass and the surrounding watermass inside of the bay mouth. These two exchange ratios can be combined into a single exchange
ratio which describes the exchange process between the outer watermass and the bay water. 相似文献
15.
Finite‐element analysis of laminated rubber bearing of building frame under seismic excitation 下载免费PDF全文
Makoto Ohsaki Tomoshi Miyamura Masayuki Kohiyama Takuzo Yamashita Masashi Yamamoto Naohiro Nakamura 《地震工程与结构动力学》2015,44(11):1881-1898
Finite element analysis is carried out for a building frame supported by laminated rubber bearings to simultaneously investigate global displacement and local stress responses under seismic excitation. The frame members and the rubber bearings are discretized into hexahedral solid elements with more than 3 million degrees of freedom. The material property of rubber is represented by the Ogden model, and the frame is assumed to remain in elastic range. It is shown that the time histories of non‐uniform stress distribution and rocking behavior of the rubber bearings under a frame subjected to seismic excitation can be successfully evaluated, and detailed responses of base and frame can be evaluated through large‐scale finite element analysis. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
16.
17.
Makoto Ideta 《Astrophysics and Space Science》2003,284(2):531-534
Dynamical evolution of N-body bars embedded in spherical and prolate dark matter halos is investigated. In particular, the configuration such that
galactic disks are placed in the plane perpendicular to the equatorial plane of the prolate halos is considered. Such a configuration
is frequently found in cosmological simulations. N-body disks embedded in a fixed external halo potential were simulated, so that the barred structure was formed via dynamical
instability in initially cool disks. In the subsequent evolution, bars in prolate halos dissolved gradually with time, while
the bar pattern in spherical halos remained almost unchanged until the end of simulations. The e-folding time of bars suggest
that they could be destroyed in a time smaller than a Hubble time.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
18.
19.
Kazunori Zushida Makoto Takeuchi Takashi Nakajima Sae Taniguchi Yuxiao Li Yoshihiro Asahara Koshi Yamamoto 《Island Arc》2024,33(1):e12521
Zircon U–Pb dates for felsic and intermediate to mafic dikes intruding into the Ryoke granitoids and metamorphic rocks at selected outcrops in the Takamiyama area of the eastern Kii Peninsula, southwest Japan, were determined along with their geology and petrography to reveal the history of Cretaceous magmatism. At each outcrop, the felsic and intermediate to mafic dikes exhibit specific structures that are indicative of magma intermingling and have coeval intrusion ages of ca. 81–77 Ma. Our zircon U–Pb data complement previously published data, suggesting that the mafic magmatism continued intermittently from 83 to 76 Ma in the Takamiyama area and that magmatism migrated eastward within the Ryoke Belt. A comparison of intrusion ages between a dike and a host Ryoke granitoid at one outcrop indicates that the host rock experienced ductile deformation at ~88 to ~83 Ma. Judging from the small number of zircons and the concordant date distributions, we didn't recognize the evidence suggesting the partial melting of the host rocks, as Nakajima et al. (Journal of the Geological Society of Japan, 2021, 127, 69–78) reported. 相似文献
20.
An orthogonal set of principal axes is defined for earthquake ground motions along which the component variances have maximum, minimum and intermediate values and the covariances equal zero. Corresponding axes are defined which yield maximum values for the covariances. The orthogonal transformations involved are identical in form to those used in the transformation of stress. Examination of real accelerograms reveals that the major principal axis points in the general direction of the epicentre and the minor principal axis is nearly vertical. It is concluded that artificially generated components of ground motion need not be correlated statistically provided they are directed along a set of principal axes. 相似文献