PP-P differential traveltime measurement with crustal correction     

Masayuki Obayashi  Daisuke Suetsugu  Yoshio Fukao 《Geophysical Journal International》2004,157(3):1152-1162

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Occurrence of 3-hydroxy acids in microalgae and cyanobacteria and their geochemical significance     

Genki I. Matsumoto  Hideyuki Nagashima 《Geochimica et cosmochimica acta》1984,48(8):1683-1687

3-Hydroxy acids were detected in pure cultured microalgae: Chlorophyta—Chlamydomonas reinhardtii and Chlorella pyrenoidosa and Rhodophyta—Cyanidium caldarium (two strains), and cyanobacteria (Cyanophyta)—Anacystis nidulans, Phormidium foveolarum, Anabaena variabilis and Oscillatoria sp. Normal and branched (iso and anteiso) 3-hydroxy acids in the ranges of C₈-C₂₆ were found in all the samples studied at concentrations ranging from 0.036 to 2.3 and 0.000 to 0.12 mg g^?1 of dry sample, respectively. The major constituents were generally even-carbon numbered normal acids with carbon chain lengths below C₂₀. Microalgae and cyanobacteria may be the important sources of 3-hydroxy acids in natural environments.  相似文献   

U–Pb zircon geochronology of the North Pole Dome adamellite in the eastern Pilbara Craton          下载免费PDF全文

Hisashi Asanuma  Yusuke Sawaki  Shuhei Sakata  Hideyuki Obayashi  Kazue Suzuki  Kouki Kitajima  Takafumi Hirata  Shigenori Maruyama 《Island Arc》2018,27(4)

Supracrustal rocks around the North Pole Dome area, Western Australia, provide valuable information regarding early records of the evolution of crustal processes, surface environments, and biosphere. Owing to the occurrence of the oldest known microfossils, the successions at the North Pole Dome area have attracted interest from many researchers. The Paleoarchean successions (Warrawoona Group) mainly comprise mafic‐ultramafic greenstones with intercalated cherts and felsic lavas. Age constraints on the sediments have been mainly based on zircon U–Pb geochronology. However, many zircon grains have suffered from metamictization and contain anomalously high contents of common Pb, which makes interpretation of the U–Pb data complicated. In order to provide more convincing chronological constraints, an U–Pb Concordia age is widely accepted as the best estimate. Most zircons separated from two adamellites also suffered from severe metamictization. In our analyses, less metamictized domains were selected using a pre‐ablation technique in conjunction with elemental mapping, and then their U–Pb isotopic compositions were determined with a laser ablation inductively coupled plasma mass spectrometry. Most analyzed domains contained certain amounts of common Pb (²⁰⁴Pb/²⁰⁶Pb > 0.000 1), whereas three and five U–Pb data points with less common Pb (²⁰⁴Pb/²⁰⁶Pb < 0.000 1) were obtained. These U–Pb datasets yielded U–Pb Concordia ages of ca 3 445 Ma and 3 454 Ma, respectively. These ages represent the timing of the adamellite intrusion, and constrain the minimum depositional age of the Warrawoona Group. In addition, a single xenocrystic zircon grain showed a ²⁰⁷Pb/²⁰⁶Pb age of ca 3 545 Ma, supporting the idea that the sialic basement of the Pilbara Craton existed prior to 3 500 Ma. The in situ U–Pb zircon dating combined with the pre‐ablation technique has the potentials to identify non‐metamictized parts and to yield precise and accurate geochronological data even from partially metamictized zircons.  相似文献   

A dataset of continental river discharge based on JRA-55 for use in a global ocean circulation model     

Tatsuo Suzuki  Dai Yamazaki  Hiroyuki Tsujino  Yoshiki Komuro  Hideyuki Nakano  Shogo Urakawa 《Journal of Oceanography》2018,74(4):421-429

A dataset of historical river discharge into oceans was created using the CaMa-Flood global river routing model and adjusted runoff from the land component of JRA-55. The major rivers were well resolved with a 0.25° horizontal resolution. The total runoff on each drainage basin exhibits a distinctive bias on decadal time scales. The input runoff data were modified using 5-year low-pass-filtered multiplicative factors to fit the annual mean climatology and decadal variations in the reference dataset. The model incorporated data from 1958 to 2016. The yearly and seasonal variations of the major rivers are well represented by the model.  相似文献   

Modeling of the branches of the Tsushima Warm Current in the Eastern Japan Sea     

Hideyuki Kawamura  Toshimichi Ito  Naoki Hirose  Tetsutaro Takikawa  Jong-Hwan Yoon 《Journal of Oceanography》2009,65(4):439-454

The branches of the Tsushima Warm Current (TWC) are realistically reproduced using a three-dimensional ocean general circulation model (OGCM). Simulated structures of the First Branch and the Second Branch of the TWC (FBTWC and SBTWC) in the eastern Japan Sea are mainly addressed in this study, being compared with measurement in the period September–October 2000. This is the first numerical experiment so far in which the OGCM is laterally exerted by real volume transports measured by acoustic Doppler current profiler (ADCP) through the Tsushima Straits and the Tsugaru Strait. In addition, sea level variation measured by tide-stations along the Japanese coast as well as satellite altimeters is assimilated into the OGCM through a sequential data assimilation method. It is demonstrated that the assimilation of sea level variation at the coastal tide-stations is useful in reproducing oceanic conditions in the nearshore region. We also examine the seasonal variation of the branches of the TWC in the eastern Japan Sea in 2000. It is suggested as a consequence that the FBTWC is continuous along northwestern Honshu Island in summertime, while it degenerates along the coast between the Sado Strait and the Oga Peninsula in other seasons. On the other hand, a mainstream of the SBTWC exists with meanders and eddies in the offshore region deeper than 1000 m to the north of the Sado Island throughout the year.  相似文献   

Energy build-up and release mechanisms in solar and auroral flares     

Tatsuzo Obayashi 《Solar physics》1975,45(1):217-226

The 80 and 160 MHz radioheliograph observations of a flare-associated outburst in June 1973 reveal three distinctive type IV continuum sources: a flare continuum, an isolated moving continuum and a storm continuum, in that time sequence. The observed characteristics of the three sources and their relations in space and time are described. The observed characteristics and the interrelations between the three continuum sources are explained in terms of energetic electrons trapped and accelerated in, and ejecta moving through, an arch-like magnetic field. It is also suggested that the isolated moving source - in the present event and in similar ones - is probably quite independent of the MHD shock wave which is responsible for the preceding type II burst.  相似文献   

Geomagnetic Pulsations and the Earth's Outer Atmosphere     

T. Obayashi  J. A. Jacobs† 《Geophysical Journal International》1958,1(1):53-63

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Key problems in auroral flare processes     

Tatsuzo Obayashi 《Solar physics》1976,47(1):367-373

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HI Column Density Oscillation in Interstellar Space     

Hideyuki Kamaya 《Astrophysics and Space Science》1997,253(2):199-204

The author proposes the possibility to observe the HI column density oscillation in small scales (∼ AU-scale). If such variance of the column density were to be observed, he would suggest that the observational results show the existence of some type of waves in two-phase gas mixture. Such wave is known to be a void wave in the context of multi-phase fluid dynamics. If the variation of HI column density is representation of the void wave, we can also expect the HII density variations have anti-correlation to the HI density fluctuations, in the context of classical two phase model of interstellar medium. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

Constraint on intergalactic dust from thermal history of intergalactic medium     

Akio K. Inoue †  Hideyuki Kamaya 《Monthly notices of the Royal Astronomical Society》2003,341(3):L7-L11

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