H I observations of galaxies behind the Milky Way in the Puppis region     

Pierre Chamaraux  Jean-Louis Masnou  Ilya Kazés  Mamoru Sait&#;  Tadafumi Takata  Toru Yamada 《Monthly notices of the Royal Astronomical Society》1999,307(2):236-252

We report 21-cm H  i line observations of 161 galaxies located behind the Milky Way, in the Puppis region. The observations have been carried out with the Nançay radio telescope, resulting in 101 detections. Most of the galaxies observed appear in the ESO catalogue, and present apparent diameters larger than 1.6 arcmin. We show that the detection rate is strongly related to the apparent diameter; it is as high as 76 per cent for diameters larger than 1.6 arcmin. Half of the non-detections result, in fact, from an insufficient velocity coverage. Global parameters of the detected galaxies are computed, after a careful discussion of the correction for Galactic absorption. Our H  I data are then compared with those obtained by Kraan-Korteweg & Huchtmeier with the Effelsberg radio telescope for 20 galaxies observed in common: the agreement is excellent, implying respective uncertainties on recession velocities and on H  I fluxes lower than 10 km s⁻¹ and 2 Jy km s⁻¹ on average. Finally, we find that the detected galaxies follow well the correlation between the optical linear diameter and the H  I mass found by Haynes & Giovanelli. This result shows that our diameter corrections for Galactic absorption A_B are quite good, except for eight objects which are heavily obscured ( A_B 2.3), or have a very small diameter, lower than 0.5 arcmin.  相似文献   

U–Pb zircon ages of the Nakanogawa Group in the Hidaka Belt,northern Japan: Implications for its provenance and the protolith of the Hidaka metamorphic rocks          下载免费PDF全文

Futoshi Nanayama  Yutaka Takahashi  Toru Yamasaki  Mitsuru Nakagawa  Hideki Iwano  Tohru Danhara  Takafumi Hirata 《Island Arc》2018,27(2)

Zircon U–Pb ages of two acidic tuff and two turbidite sandstone samples from the Nakanogawa Group, Hidaka Belt, were measured to estimate its depositional age and the development of the Hokkaido Central Belt, northeast Japan. In the northern unit, homogeneous zircons from pelagic acidic tuff from a basal horizon dated to 58–57 Ma, zircons from sandstone from the upper part of the unit dated to 56–54 Ma, and zircons from acidic tuff from the uppermost part dated to 60–56 Ma and 69–63 Ma. Both of the tuff U–Pb ages are significantly older than the youngest radiolarian fossil age (66–48 Ma). Therefore, the maximum depositional age of the turbidite facies in the northern unit is 58 Ma and the younger age limit, estimated from the fossil age, is 48 Ma. In the southern unit, homogeneous zircons from turbidite sandstone dated to 58–57 Ma. Thus the depositional age of this turbidite facies was interpreted to be 66–56 Ma from the fossil age, probably close to 57 Ma. Most of the zircon U–Pb ages from the Nakanogawa Group are younger than 80 Ma, with a major peak at 60 Ma. This result implies that around Hokkaido volcanic activity occurred mainly after 80 Ma. Older zircon ages (120–80 Ma, 180–140 Ma, 340–220 Ma, 1.9 Ga, 2.2 Ga, and 2.7 Ga) give information about the provenance of other rocks in the Hidaka Belt. It is inferred that the Nakanogawa Group comprises protoliths of the upper sequence of the Hidaka Metamorphic Zone, which therefore has the same depositional age as the Nakanogawa Group (66–48 Ma). The depositional ages of the lower sequence of the Hidaka Metamorphic Zone and the Nakanogawa Group are probably the same.  相似文献   

Zircon fission‐track and U–Pb double dating using femtosecond laser ablation–inductively coupled plasma–mass spectrometry: A technical note     

Hideki Iwano  Tohru Danhara  Yugo Danhara  Saori Hirabayashi  Toru Nakajima  Harutaka Sakai  Takafumi Hirata 《Island Arc》2020,29(1)

We present a new LA–ICP–MS system for zircon fission‐track (FT) and U–Pb double dating, whereby a femtosecond laser combined with galvanometric optics simultaneously ablates multiple spots to measure average surface U contents. The U contents of zircon measured by LA–ICP–MS and standardized with the NIST SRM610 glass are comparable to those measured by the induced FT method, and have smaller analytical errors. LA–ICP–MS FT dating of seven zircon samples including three IUGS age standards is as accurate as the external detector method, but can give a higher‐precision age depending on the counting statistics of the U content measurement. Double dating of the IUGS age standards gives FT and U–Pb ages that are in agreement. A chip of the Nancy 91500 zircon has a homogeneous U content of 84 ppm, suggesting the possibility of using this zircon as a matrix‐matched U‐standard for FT dating. When using the Nancy 91500 zircon as a U‐standard, a zeta calibration value of 42–43 year cm² for LA–ICP–MS FT dating is obtained. While this value is strictly valid only for the particular session, it can serve as a reference for other studies.  相似文献   

Structure and dynamics of the sudden acceleration of Kuroshio off Cape Shionomisaki   总被引：1，自引：1，他引：0  

Toru Miyama  Yasumasa Miyazawa 《Ocean Dynamics》2013,63(2-3):265-281

A sudden acceleration of the Kuroshio jet appears off Cape Shionomisaki in the high-resolution (horizontal resolution of 1/36°) JCOPE 2 ocean reanalysis data. Using this dataset, we investigated the structure of the Kuroshio acceleration. The increase in the velocity of the current is accompanied by a downstream flow separation from the coast and an outcrop of cold temperature inshore. The acceleration of Kuroshio appears when it takes a near-shore path. Cape Shionomisaki amplifies the responses to the Kuroshio flow by creating the zonal velocity acceleration toward the downstream region when the Kuroshio flows closer to the coast. The Kuroshio acceleration coincided with the topographic ridge on the continental shelf near Cape Shionomisaki. This relation suggests that the dynamics of the acceleration is linked to the topographic feature. We proposed an explanation of the Kuroshio acceleration using a hydraulic control theory. An analytical solution was applied to the coastal topography around the Kii Peninsula. The solution captured some aspects of the Kuroshio acceleration.  相似文献   

Performances of Landfill Liners under Dry and Wet Conditions     

Saravanan Mariappan  Masashi Kamon  Faisal Haji Ali  Takeshi Katsumi  Tomoyuki Akai  Toru Inui  Masaki Nishimura 《Geotechnical and Geological Engineering》2011,29(5):881-898

This paper addresses the study conducted on the performance of landfill liner interface parameters. Interface shear strength parameters for various combinations of 9 different lining materials were studied and presented in this paper. This comprehensive testing program covers the interfaces between: (1) soil and compacted clay liner (CCL), (2) geomembrane (HDPEs or PVC) and soil, (3) geosynthetic clay liner (GCL)/CCL and soil, (4) geomembrane and geotextile, (5) geotextile and soil, (6) geotextile and GCL/CCL, and (7) geomembrane and GCL/CCL. The experiments were conducted for both at dry or optimum moisture condition and at saturated or wet condition. The interface performance under both conditions were compared to access the material performances. Tabulated summaries of interface test data under dry or optimum moisture condition (OMO) and saturated or wet condition are presented in the paper.  相似文献   

Erratum to: Temperature scaling pattern dependence on representative concentration pathway emission scenarios     

Yasuhiro Ishizaki  Hideo Shiogama  Seita Emori  Tokuta Yokohata  Toru Nozawa  Tomoo Ogura  Manabu Abe  Masakazu Yoshimori  Kiyoshi Takahashi 《Climatic change》2014,125(2):277-277

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Reproductive biology of Ilisha elongata (Teleostei: Pristigasteridae) in Ariake Sound,Japan: Implications for estuarine fish conservation in Asia     

Jie Zhang  Toru Takita  Chunguang Zhang 《Estuarine, Coastal and Shelf Science》2009

Elongate ilisha (Ilisha enlongata) is a commercially important species that contributes to clupeoid fisheries in Asian countries. In the present study, the reproductive biology of I. elongata in Ariake Sound, Japan is determined for the first time. Six maturity stages were described using ovarian and testicular histology throughout the annual cycle. The spawning season in Ariake Sound lasts from May to July, with peak spawning activity in May and June. Age at first maturity was estimated to be 2 years, with a few exceptions of 1 year in well-developed males. Ovaries that contained both tertiary yolk oocytes and postovulatory follicles occurred from late May to late July, indicating that I. elongata is a multiple spawner. The size–frequency distribution of oocytes provided evidence for its multiple spawning and accuracy of the fecundity estimates. The batch fecundity of this species was estimated at between 22,200 and 270,900 eggs per individual, increasing with age between two and six years. The present findings on the reproductive strategy of I. elongata in Ariake Sound are generally consistent with those in temperate or subtropical populations, but quite different from those of tropical population where first maturation occurs around 200 days and life spans are shorter, with a maximum age less than 3 years. The conservation implications of this reproductive strategy in a harsh, variable environment in Asian countries are also discussed.  相似文献   

Satellite-measured temporal and spatial variability of the Tokachi River plume     

Tukimat Lihan  Sei-Ichi SaitohTakahiro Iida  Toru HirawakeKohji Iida 《Estuarine, Coastal and Shelf Science》2008

River plumes have important effects on marine ecosystems. Variation in the extent and dispersal of river plumes is often associated with river discharge, wind characteristics and ocean circulation. The objectives of this study were to identify the Tokachi River plume by satellite, determine its relationship with river discharge and clarify its temporal and spatial dynamics. SeaWiFS multispectral satellite data (normalized water-leaving radiance: nL_w) with 1.1 km spatial resolution were used to determine the spatial and temporal variability of the plume during 1998–2002. Supervised maximum likelihood classification using six channels of nL_w at 412, 443, 490, 510, 555 and 670 nm with each band's spectral signature statistic was used to define classes of surface water and to estimate the plume area. Supervised maximum likelihood classification separated three to four classes of coastal water based on optical characteristics as a result of wind stress events. The satellite-observed plume area was correlated with the amount of river discharge from April to October. The plume distribution patterns were influenced by wind direction and magnitude, the occurrences of a near-shore eddy field and surface currents. Empirical orthogonal function (EOF) was used to express the spatial and temporal variability of the plume using anomalies of nL_w(555) monthly averaged images. The first mode (44% of variance) showed the turbid plume distribution resulting from re-suspension by strong wind mixing along the coast during winter. This mode also showed the plume was distributed along-shelf direction in spring to early autumn. The second mode (17% of variance) showed spring pattern across-shelf direction. EOF analysis also explained the interannual variability of the plume signature, which might have been affected by the flow of the Oyashio Current and the occurrence of a near-shore eddy field.  相似文献   

Evapotranspiration from a wet temperate grassland and its sensitivity to microenvironmental variables     

S.‐G. Li  C.‐T. Lai  G. Lee  S. Shimoda  T. Yokoyama  A. Higuchi  T. Oikawa 《水文研究》2005,19(2):517-532

The eddy covariance and energy balance method was employed to determine evapotranspiration (LE) over a wet temperate C3–C4 co‐existing grassland in Japan. After sensible heat flux (H) was estimated via the eddy covariance technique, LE was calculated as the residual of the energy budget with calibration against the direct measurements of LE by a lysimeter. Daily mean LE varied from 0·8 to 10·5 MJ d⁻¹, with a peak at 16·5 MJ d⁻¹ in late July to early August. Day‐to‐day and seasonal variability in LE was affected appreciably by net radiation (R_n), atmospheric vapour pressure deficit (VPD), canopy surface conductance (g_c) and leaf area index (LAI). Before the canopy closure, LE responded to LAI in a linear manner. However, LE decreased with increasing LAI later in summer. Daytime variation in the decoupling coefficient (Ω) demonstrates that the canopy decoupled from the atmosphere in the morning and LE was primarily driven by the available energy, while in the afternoon the canopy partially coupled to the atmosphere so that LE was sensitive to VPD and g_c. Throughout the whole measurement period, Ω was generally larger than 0·5, suggesting that the available energy contributes more to LE than VPD. Copyright © 2004 John Wiley & Sons, Ltd.  相似文献   

Photographic Observations of the 1996 Leonid Fireballs in Japan     

Shiba  Y.  Shimoda  C.  Maruyama  T.  Okumura  S.  Tomita  M.  Murasawa  A.  Ohtsuka  K.  Tomioka  H.  Hidaka  E. 《Earth, Moon, and Planets》1997,77(1):47-54

Several Leonid fireballs were successfully photographed by the Japanese Fireball Network and by other observers in Japan on 16 November, 1996. A totals of seven of these were simultaneously observed from two or more stations, from which the orbital and physical data were deduced. The radiant of these fireballs were very small, only 0.1°, similar to that of the 1991 Perseids. The 1996 Leonids showed a lower magnitude distribution index similar to those obtained in the 1961 and 1965 Leonids. All of these showers occurred before perihelion passage of the parent comet. We conclude that we have already encountered the elongated front part of the dust trail of the Leonid parent comet, where the trail is probably composed of larger dust particles. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献