Solid state physics and cooling of neutron stars     

Sachiko Tsuruta 《Astrophysics and Space Science》1975,34(1):199-208

First we show the possible effect of the ‘magnetic’ condensation on cooling of neutron stars. Its observational significance (especially for younger pulsars such as the Crab pulsar) is emphasized. Other effects of solid state physics on cooling are also discussed.  相似文献   

URCA shells in dense stellar interiors     

Sachiko Tsuruta  A. G. W. Cameron 《Astrophysics and Space Science》1970,7(3):374-406

Thermal and vibrational energy losses due to URCA shells in stellar interiors are calculated. Analytic expressions are derived for semidegenerate, relativistic electrons. Results are given for more general cases calculated with a computer. The calculations are carried out for a large number of nuclei that may contribute to URCA energy losses in various stages of stellar evolution. An illustration is given of the cooling and vibrational damping of a white dwarf. For a central Fermi energy 5 MeV, the internal temperature of the star should be reduced to the order of 10⁶ K and the relative vibrational amplitude should be reduced to the order of 10^–5 on a time scale of 10⁹ yr. URCA shells are present, the URCA neutrino energy loss dominates in the temperature region up to about 2×10⁹ K.  相似文献   

Interannual Changes of the Winter to Early Spring Biomass and Composition of Mesozooplankton in the Kuroshio Region in Relation to Climatic Factors     

Kaoru Nakata  Sachiko Koyama 《Journal of Oceanography》2003,59(2):225-234

Interannual variations of biomass of major mesozooplankton groups (Cnidaria, Chaetognatha, Copepoda, Crustacea other than copepods, Tunicata) in the January to March period were examined in the slope, Kuroshio and offshore waters off the Pacific coast of western Japan (western region) from 1971 to 1988 and off central Japan (central region) from 1971 to 1989. The mean biomass for each year of most of the mesozooplankton groups was high in the early 1970s and tended to decrease (in the western region) or to have dropped to a lower level (in the central region) after the mid-1970s. Stepwise multiple linear regression analyses of the mean biomass for each year of each mesozooplankton group in the Kuroshio in both regions against climatic factors revealed that the biomass was related positively to wind speed. It is therefore considered that the nutrient supply to the upper layers limits the production of many of the mesozooplankton groups examined in the Kuroshio, even in winter. Similar relationships were also found for the biomass of Copepoda, non-copepod Crustacea and Tunicata in the offshore water in the western region. The percentage of copepods in the biomass in the central region seemed to decrease under high water temperature conditions, while that of Chaetgnatha tended to increase. Climatic factors thus largely influenced the interannual variations of biomass and composition of mesozooplankton in and near the Kuroshio during the winter to early spring period. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

Further studies on the feeding habits ofSagitta nagae alvariño in Suruga Bay,central Japan     

Sachiko Nagasawa  Ryuzo Marumo 《Journal of Oceanography》1976,32(5):209-218

The feeding ofSagitta nagae was analyzed in connection with food chains in the pelagic and near-bottom communities of Suruga Bay. The following results are obtained: (1)S. nagae feeds on dominant copepod species both in the free water (upper water layers) and the near-bottom habitats; (2)S. nagae did not show any food-size selection in the range of 0.2 to 1.2 mm in cephalothorax width and height of copepods; (3) Feeding activity ofS. nagae in the free water is highest at night, while in the near-bottom habitat the species feeds more actively during the day than at night; and (4)S. nagae migrates between the bottom and free water and plays an important role in shallow water by connecting the near-bottom community with the pelagic community.  相似文献   

Seasonal Variations in the Sea off Sanriku Coast, Japan     

Sachiko Oguma  Toru Suzuki  Yutaka Nagata 《Journal of Oceanography》2002,58(6):825-835

The temperature and salinity data obtained by the Iwate Fisheries Technology Center for the 25-year period from 1971 to 1995 were analyzed to clarify the seasonal variations in the sea off Sanriku, Japan. The variations of three typical waters found in this region, the Tsugaru Current water, the Oyashio water, and the Kuroshio water are discussed in terms, of a T-S scatter diagram referring to the water mass classification proposed by Hanawa and Mitsudera (1986). The mean temperature and salinity fields averaged for each month show clear seasonal variation. Distributions of the Tsugaru Current water and the Oyashio water can barely be distinguished in the fields deeper than 200 m since the Tsugaru Current has a shallow structure; however, the fields at 100 m depth indicate remarkable seasonal variation in the area of the Tsugaru Current. At 100 m depth, the temperature and salinity fronts between the Tsugaru Current water and the Oyashio water gradually disappear in January through April, appear again in May, then become clearest in September. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

Pelagic chaetognaths in Sagami Bay and Suruga Bay,Central Japan     

Ryuzo Marumo  Sachiko Nagasawa 《Journal of Oceanography》1973,29(6):267-275

Pelagic chaetognaths in Sagami Bay and Suruga Bay, Central Japan, were studied. Their community structure was very similar in both of these bays. Four genera and 26 species were identified. In Sagami Bay the habitat segregation by depths was clearly obtained. The population and species number of epipelagic (0–200 m) chaetognaths were larger in summer than in winter. The populations of meso- (200–500 m) and bathypelagic (500–1,000 m) species were smaller than that of epipelagic ones and fairly stable seasonally.  相似文献   

Bacterial invasion of chaetognaths under laboratory and natural conditions     

Sachiko Nagasawa  Usio Simidu  Takahisa Nemoto 《Journal of Oceanography》1984,40(5):327-333

Chaetognaths are an abundant component of the plankton and are usually the most important carnivores. Head or tail damage is often found in chaetognath specimens from the laboratory and the sea. Examination by light and scanning electron microscopy (SEM) of specimens with such damage has revealed that bacterial invasion occurs in chaetognaths under laboratory and natural conditions. Living chaetognaths which cease feeding are found to have large numbers of attached bacteria and some parts of their body become opaque. Once they are attacked in this manner the body appears to be a mass of bacteria. Examination of field samples has shown that similar bacterial attacks occur in the sea. Bacterial growth is common inside the muscle tissue of field specimens. Up to 13.3% of two dominant species of chaetognaths in Suruga Bay are attacked by bacteria.  相似文献   

Feeding of a pelagic chaetognath,Sagitta nagae Alvariño in Suruga Bay,Central Japan     

Sachiko Nagasawa  Ryuzo Marumo 《Journal of Oceanography》1972,28(5):181-186

The feeding ofSagitta nagae, the most predominant chaetognath species in Suruga Bay, was studied. Specimens were collected with ORI-100 net (1.0 mm in mesh aperture) and MTD net (0.35 mm in mesh aperture) and were fixed with neutralized formalin. The main food organisms ofSagitta nagae were the copepods,Candacia bipinnata, Calanus pacificus andPareuchaeta russelli. The food-containing ratio (P/T, %) was higher at night and lower in the daytime. Here, P is the number ofSagitta containing food organisms in the gut and T is the total number ofSagitta examined. P/T was almost constant vertically in the upper 100 m layer. P/T was generally influenced neither by food density nor by the copepod numbers perSagitta in this study.Sagitta nagae took food throughout life. Food ingested bySagitta per day was calculated as 37.6% ofSagitta in dry weight.  相似文献   

Inter-seasonal variability of internal tides in the western Bay of Bengal     

Himansu K. Pradhan  A. D. Rao  Sachiko Mohanty 《Natural Hazards》2016,84(2):809-820

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An attempt to characterize phase Q: Noble gas, Raman spectroscopy and transmission electron microscopy in residues prepared from the Allende meteorite     

Jun-ichi Matsuda  Kazuhiko Morishita  Chie Miyakawa  Sachiko Amari  Seiji Takeda 《Geochimica et cosmochimica acta》2010,74(18):5398-5409

We have prepared a HF-HCl residue and its oxidized residue of the Allende meteorite and have measured the elemental concentrations and the isotopic compositions of noble gases. In the HF-HCl reside, noble gases are enriched in colloidal fraction compared to the non-colloidal fraction by a factor of 2-4. The heavy noble gases were evidently lost after the oxidization, indicating that phase Q (carrier of planetary heavy noble gases) was removed by the oxidation. The Raman spectroscopic parameters show that the colloidal fraction of the HF-HCl residue is more amorphous compared to the non-colloidal fraction. As the ion irradiation converts carbon into a more amorphous form, our result indicates that the “plasma model” is more plausible than the “labyrinth model” as the origin of phase Q. TEM (Transmission Electron Microscope) observations also show such a trace of ion irradiation. While the TEM observations did not show any large difference between the HF-HCl residue and its oxidized residue, the Raman spectroscopic parameters changed discretely resulting from the oxidization. This observation indicates that the oxidization not only dissolved and removed oxidized carbon, but also changed the carbon structure itself to a more amorphous (disordered) state. The Raman spectroscopic results indicate the possibility that release of Q-gas during oxidation is not accompanied by mass loss and that the release of Q-gas simply resulted from rearrangement of carbon structure during oxidation.  相似文献