Effects of a physical librations of the moon caused by a liquid core,and determination of the fourth mode of a free libration     

Yu. V. Barkin  H. Hanada  K. Matsumoto  S. Sasaki  M. Yu. Barkin 《Solar System Research》2014,48(6):403-419

An analytical theory of lunar physical librations based on its two-layer model consisting of a non-spherical solid mantle and ellipsoidal liquid core is developed. The Moon moves on a high-precision orbit in the gravitational field of the Earth and other celestial bodies. The defined fourth mode of a free libration is caused by the influence of the liquid core, with a long period of 205.7 yr, with amplitude S = 0″0395 and with an initial phase Π₀ = ?134° (for the initial epoch 2000.0). Estimates of dynamic (meridional) oblatenesses of a liquid core of the Moon have been estimated: ?_D = 4.42 × 10^?4, μ_D = 2.83 × 10^?4 (?_D + μ_D = 7.24 × 10^?4). These results have been obtained as a result of comparison of the developed analytical theory of physical librations of the Moon with the empirical theory of librations of the Moon constructed on the basis of laser observations.  相似文献   

The influence of multiple diffraction on the space group determination of orthopyroxene,spodumene, low omphacite and pigeonite     

Satoshi Sasaki  Takeo Matsumoto  Chikako Sawada 《Physics and Chemistry of Minerals》1981,7(6):260-267

Forbidden reflections of some pyroxenes described as having a lower symmetry than Pbca or C2/c have been examined, mainly using the detailed ψ-scanning method of the four-circle automated diffractometer. All reflections violating the systematic absences of Pbca orthopyroxene, C2/c spodumene, P2/n omphacite and P2₁/c pigeonite were found to be due to the Umweganregung process of multiple diffraction; the Umweganregung peaks observed for the ψ azimuth were indexed in terms of a four-circle geometry. Thus, the space groups of orthopyroxene, α spodumene, low omphacite and low pigeonite were confirmed to be Pbca, C2/c, P2/n and P2₁/c, respectively.  相似文献   

Osmium isotope ratios of PGM grains associated with the Freetown Layered Complex,Sierra Leone,and their origin     

Keiko Hattori  Louis J. Cabri  Stanley R. Hart 《Contributions to Mineralogy and Petrology》1991,109(1):10-18

Osmium isotope ratios for two types of platinum group mineral (PGM) nuggets of eluvial (residual) origin, associated with the Freetown Layered Gabbro Complex, were determined in-situ using an ion microprobe. The values for erlichmanite nuggets are 1.08. Those for PGM inclusions in Pt–Fe alloy nuggets are higher, ranging from 1.2 to 2.1. Ratios of¹⁸⁷Os/¹⁸⁶Os vary between the nuggets, but they are consistent within individual nuggest. The data suggest early formation of the erlichmanite nuggets, prior to a postulated substantial contribution of crustal Os. The Pt–Fe alloy nuggets, on the other hand, were formed later in a residual melt which was contaminated by crustal Os due to the assimilation (<10%) or the gaseous/fluid transport of Os from Archaean host rocks into the magma. The lack of systematic mineralogical and chemical changes of the Complex and extensive granulitization in the adjacent host rocks and xenoliths may favor the latter process.The lack of high¹⁸⁷Os/¹⁸⁶Os ratios, consistent¹⁸⁷Os/¹⁸⁶Os values within individual nuggets and their textures and mineralogy suggest that the studied PGM nuggets were not formed during lateritization or in low-temperature depositional environments.  相似文献   

Effect of El Nino on migration and larval transport of the Japanese eel (Anguilla japonica)     

Kim  Heeyong; Kimura  Shingo; Shinoda  Akira; Kitagawa  Takashi; Sasai  Yoshikazu; Sasaki  Hideharu 《ICES Journal of Marine Science》2007,64(7):1387-1395

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Myctophid fishes of the genusMyctophum (myctophidae) in the pacific and Indian oceans     

Kouichi Kawaguchi  Keiko Aioi 《Journal of Oceanography》1972,28(4):161-175

The key to the nine species:M. nitidulum Garman,M. aurolaternatum Garman,M. spinosum (Steindachner),M. asperum Richardson,M. obtusirostrum Tåning,M. orientale (Gilbert),M. phengodes (Lütken),M. selenoides Wisner andM. brachygnathum (Bleeker), was prepared for the genusMyctophum, typical surface migrating myctophid fishes, from the Pacific and Indian Oceans. The three species ofM. cuvieri (Castelnau),M. indicus (Day),M. novaeseelandidae (Steindachner) were excluded from the present key, since they have not been reported since they were originally described.M. lychnobium Bolin formsM. spinosumlychnobium complex and was also excluded. The systematic accounts were given for seven species.  相似文献   

Geostrophic balance of the Kuroshio as inferred from surface current and sea level observations     

Kunio Rikiishi  Katsunori Sasaki 《Journal of Oceanography》1988,44(6):305-314

Historical observations of the surface current and daily mean sea level during the period 1965–1985 are analyzed in order to examine the geostrophic balance of the Kuroshio current in the Tokara Strait and near the Izu Islands. The variation in the sea level difference across the Kuroshio is associated with a variation in surface current velocity as predicted by the theory of geostrophic balance. However, the slope of the linear relation between the current velocity and sea level difference is smaller than the theoretically predicted value by about 30%. This disagreement may be ascribed to the effects of the centrifugal force and the occasional rise in sea level due to storm surges.Absolute mean sea level differences between the tidal stations are estimated by making use of the empirical relationship between the surface current and sea level difference. Estimated differences are: 87.4±22.1 cm between Naze and Nishinoomote, 24.3±9.2 cm between Miyake and Minamiizu, 41.3±17.7 cm between Miyake and Mera and 45.1±8.8 cm between Hachijyo and Miyake. The absolute value of sea level difference between Miyake and Minamiizu and that between Miyake and Mera may be about 30 cm, since geodetic levelling tells us that the mean sea level at Minamiizu is nearly equal to that at Mera.  相似文献   

The effects of petroleum hydrocarbons on lipid metabolism and energetics of larval development and metamorphosis in the american lobster (homarus americanus Milne Edwards)     

Judith M. Capuzzo  Bruce A. Lancaster  Glenn C. Sasaki 《Marine environmental research》1984,14(1-4)

In studies with larval stages of the American lobster (Homarus americanus) exposed to a sublethal concentration of South Louisiana crude oil, the normal patterns of lipid storage, utilization and synthesis during larval development and metamorphosis were altered with oil exposure. Increased rates of protein catabolism, delayed molting and reduced growth were also evident among oil-exposed lobster larvae and suggest either deficiency or immobilization of lipid reserves. From analyses of lipid class composition of control and oil-exposed lobster larvae, it is evident that oil-exposed larvae have consistently lower levels of triacylglycerols (the major energy store) and higher levels of sterols than control larvae. Decreased ratios of non-essential fatty acids (both saturated and unsaturated) and increased ratios of essential fatty acids were detected in the neutral lipid pools of oil-exposed larvae that suggest both decreased storage of fatty acids in energy reserves and decreased mobilization of essential fatty acids into phospholipid pools. The fatty acid distribution in the phospholipid pools of oil-exposed larvae, however, varied little from control values and reflects a tendency to preserve the integrity of these structural lipids. Increases in sterol levels may be related to decreased mobilization of cholesterol or other sterols and/or transformation of cholesterol into metabolic pathways including the biosynthesis of ecdysterone.Oil-exposed animals contained trace quantities of benzene, thiophene, toluene, alkylcyclohexane and alkylbenzenes, detected with GC-MS analyses. No naphthalene, dimethylnaphthalene, higher molecular weight aromatics or their phenolic derivatives were detected; their absence may be related to either the detection limits of the methodology used or extremely rapid metabolism and turnover of these components. Alterations in lipid metabolism may account for the developmental and energetic abnormalities observed in marine crustaceans. It cannot be ruled out, however, that decreased lipid utilization, synthesis and mobilization may be a defense mechanism against incorporating lipophilic components of petroleum hydrocarbons in metabolic pathways, and that disruption in energetics and development is a consequence of the reduction in energy available for growth and molting.  相似文献   

Thermohaline staircases in the Warm-Core Ring off Cape Erimo,Hokkaido and their fluxes due to salt finger     

Hideo Miyake  Seiji Sasaki  Hidekazu Yamaguchi  Kiyoshi Masuda  Gen Anma  Yoshihiko Kamei 《Journal of Oceanography》1995,51(1):99-109

Thermohaline staircases off Cape Erimo, Hokkaido are described and their physical properties are compared with those in other seas. The mean fluxes for heat and salt across the interface induced by salt finger were estimated as 105 cal cm^–2d^–1, and 0.03 g cm^–2d^–1, respectively. These values were in the same order as those in Caribbean Sea. The effective eddy diffusivities were also in the same order as the Caribbean ones. This suggests that the double-diffusive convection plays on important role on the water mass conversions occurring in the interfrontal zone between the Oyashio and the Kuroshio Waters.  相似文献   

Mechanism of Nutrient Supply to Warm-Core Ring off Sanriku, Japan     

Katsuyuki Sasaki  Yutaka Hiroe 《Journal of Oceanography》2002,58(5):683-690

The mechanism by which nutrient is supplied to a warm-core ring (WCR) was investigated in order to understand the greater productivity of WCR than that of the Kuroshio, where the WCR originattes. A single WCR was observed in January and May, 1997. The thermostad (a layer of isothermal and isohaline water) of the WCR had different properties from January to May, the differences: Δwater temperature: −0.698°C, Δsalinity: −0.048, Δsigma θ: +0.072, Δnitrite+nitrate-N: +1.83 μM, Δphosphate: +0.011 μM and Δsilicate: +3.2 μM. We examined three possible mechanisms for nutrient supply to WCR in winter, namely: 1) inflow of the Oyashio surface water into WCR; 2) isopycnal mixing with Oyashio water; 3) entrainment of the water below the WCR into the WCR. The results were as follows: 1) When the decrease of salinity was due to the inflow of the Oyashio surface water, the increase of nutrients (nitrite+nitrate-N, phosphate-P and silicate-Si) was estimated to be only 17–27% of the observed increase. 2) When the decrease of salinity was due to isopycnal mixing, the increase of nutrients was estimated to be 30–42% of the observed increase. 3) When the decrease of salinity in the WCR in May was due to entrainment of the water below the WCR in winter by convection, the mixing depth was calculated be 620 m according to the salt budget. The increase of nutrients in this case was calculated to be 82–95% of the observed increase. The main mechanism of nutrient supply to WCR was concluded to be due to the entrainment of the water below the WCR by winter mixing. This revised version was published online in August 2006 with corrections to the Cover Date.  相似文献   

Loss Processes of Sinking Fecal Pellets of Zooplankton in the Mesopelagic Layers of the Antarctic Marginal Ice Zone     

Hidekatsu Suzuki  Hiroshi Sasaki  Mitsuo Fukuchi 《Journal of Oceanography》2003,59(6):809-818

A time-series sediment trap deployment was carried out in the marginal ice zone (MIZ) of the Antarctic Ocean (64°42′ S, 139°58′E; sea depth of 2930 m), during the austral summer. Cylindrical fecal pellets were the predominant sinking particles at 537 m in the middle of January and most of them disappeared below that depth, the loss of which were 25.3 mg C m⁻² day⁻¹ in the depth range of 537–796 m. Small-sized sinking particles other than fecal pellets increased in that depth range. Analyses of fecal pellets for remnant DNA corresponding to 16S mitochondrial RNA and 28S ribosomal RNA suggested that the large cylindrical fecal pellets at 537 m were produced by Antarctic krill (Euphausia superba) and copepods. According to the presence of the DNA associated with sinking particles, E. superba fecal pellets rapidly disappeared below 537 m, while copepod fecal pellets still remained in the mesopelagic and bathypelagic layers. Small-sized amorphous sinking particles at 537 m also contained E. superba- and copepod-derived DNA. The abundance of trap-collected copepods (Oithona spp. and Oncaea spp.) which are known to be coprophagous increased at 796 m where many fecal pellets disappeared. We suggest that those rapidly sinking pellets were fragmented by copepods with intensified coprorhexy activity (fragmentation of fecal pellets) in the mesopelagic layers, reducing their sinking rates. These smaller and slower sinking particles can be important food sources for detritivorus or coprophagous animals in mesopelagic and bathypelagic layers in the MIZ. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献