Online hybrid test by Internet linkage of distributed test‐analysis domains Earthquake Engineering and Structural Dynamics 2006; 35(12):1581–1583     

Peng Pan  Masayoshi Nakashima  Motohide Tada 《地震工程与结构动力学》2006,35(12):1585-1585

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Growth and succession patterns of major phylogenetic groups of marine bacteria during a mesocosm diatom bloom     

Yuya Tada  Akito Taniguchi  Yuki Sato-Takabe  Koji Hamasaki 《Journal of Oceanography》2012,68(4):509-519

Our objective was to track microbial processes associated with serial degradation of organic matter derived from algal blooms. To do this, we analyzed population fluctuations and growth responses of major phylogenetic groups of free-living marine bacteria. We used bromodeoxyuridine immunocytochemistry–fluorescence in situ hybridization methodology to examine marine bacterial community development during and after a diatom bloom in a mesocosm. We revealed that the Roseobacter/Rhodobacter, SAR11, Alteromonas, and Bacteroidetes groups were clearly major phylotypes responsible for most free-living bacterial biomass and production throughout the experiment. The clearest bacterial response was a proliferation of the Alteromonas group (cells with large volumes) during development of the bloom (up to 30?% of actively growing cells). Populations of these bacteria declined sharply thereafter, likely due to grazing. Alteromonas group responses suggest that these bacteria strongly influenced the flux of organic matter at an early bloom stage. The growth potential of Bacteroidetes was relatively large as the bloom peaked; this early development probably contributed to the initial stage of bloom decomposition. In contrast, the contribution of Roseobacter/Rhodobacter to total bacterial production increased at a late stage of decomposing of the bloom. The contributions of Betaproteobacteria, SAR11, and SAR86 groups to total bacterial abundance and production were relatively minor throughout the experiment. These results imply that the ability to utilize organic matter derived from diatoms varies among bacterial phylotypes, and, frequently, less abundant but ecological specialist taxa such as Alteromonas may play major roles in the flux of organic matter during diatom blooms.  相似文献   

Online hybrid test by internet linkage of distributed test‐analysis domains     

Peng Pan  Motohide Tada  Masayoshi Nakashima 《地震工程与结构动力学》2005,34(11):1407-1425

Online hybrid tests (called the online tests), particularly when combined with substructuring techniques, are able to conduct large‐scale tests. An extension of this technique is to combine multiple loading tests conducted in remote locations and to integrate the tests with large numerical analysis codes. In this study, a new Internet online test system is developed in which a physical test is conducted in one place, the associated numerical analysis is performed in a remote location, and the two locations communicate over the Internet. To implement the system, a technique that links test and analysis domains located at different places is proposed, and an Internet data exchange interface is devised to allow data communication across Internet. A practical method that utilizes standard protocols implemented by operating systems for sharing files and folders is adopted to ensure stable and robust communication between remotely located servers that commonly protect themselves by strict firewalls. To combine the online test with a finite element program formulated in an incremental form and adopting an implicit integration scheme, a tangent stiffness prediction procedure is proposed. In this procedure, a tangent stiffness is estimated based on a few previous steps of experimental data. Using the system devised, tests on a base‐isolated structure were carried out. Here, the base‐isolation layer was taken as the tested part and tested in Kyoto University, Japan, and the superstructure was modelled by means of a finite element program and analysed in a computer located in Osaka University. A series of physical Internet online tests were carried out, with the integration time interval and the method of tangent stiffness prediction as the major parameters. The tests demonstrated that the Internet communication was very stable and robust, without malfunctions. The proposed method of stiffness prediction was effective even when the experimental hysteresis curves exhibited complex behaviour, thereby ensuring accurate simulation for the earthquake response of the entire structure. Copyright © 2005 John Wiley & Sons, Ltd.  相似文献   

Temporal change of interplate coupling in northeastern Japan during 1995–2002 estimated from continuous GPS observations     

Takuya Nishimura  Tomowo Hirasawa  Shin'ichi Miyazaki  Takeshi Sagiya  Takashi Tada  Satoshi Miura  Kazuo Tanaka 《Geophysical Journal International》2004,157(2):901-916

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Classification of Japanese rivers by heavy metals in bottom mud     

Fumi Tada  Hideo Nishida  Masaya Miyai  Shizuo Suzuki 《Environmental Geology》1982,4(3-4):217-222

Bottom mud was collected from the upper and lower reaches of 92 rivers in Japan to determine the distribution of 0.5N-HCI-soluble heavy metals. The average concentrations of Cu, Zn, Pb, and Cd in the mud from the lower reaches were from two to three times higher than those in the upper reaches. Japanese rivers were classified according to the degree of heavy metal pollution by using the values of 0.5N-HCI-soluble metals in the lower reaches of rivers. The content of 0.5N-HCI-soluble heavy metals in the mud of the upper reaches was used as the standard value. The classification of rivers was made by a cluster analysis according to Euclidian distance. As a result, rivers in Japan could be classified into three groups based on the degree of metal pollution, and the classification was in agreement with the pollution index.  相似文献   

Simple estimation of penetration rate of light in intertidal sediments     

Kazuhiko Ichimi  Kuninao Tada  Shigeru Montani 《Journal of Oceanography》2008,64(3):399-404

A simple estimation of light penetration in tidal flat sediments was developed using various sediment size fractions and their attenuation rate of irradiance. The attenuation coefficients of the sediment size fractions of 63–125, 125–250, 250–500, 500–1000 μm and 1000–2000 μm were 8.10, 4.08, 2.92, 2.12 and 1.44 mm⁻¹, respectively. Using the average attenuation coefficient of the particle size fractions in the sediment, the calculated attenuation coefficient agreed well with the actual attenuation coefficient. The method presented gives a photo-parameter to predict productivity in intertidal sediments, given only the particle size fraction.  相似文献   

Dynamics of microphytobenthic biomass in a coastal area of western Seto Inland Sea, Japan   总被引：2，自引：0，他引：2  

Hitomi Yamaguchi  Shigeru Montani  Hiroaki Tsutsumi  Ken-ichiro Hamada  Naoko Ueda  Kuninao Tada 《Estuarine, Coastal and Shelf Science》2007,75(4):423-432

This study focused on the causes of the variation in microphytobenthic biomass and the effects of this variation on macrobenthic animals in the western Seto Inland Sea, Japan, where the importance of microphytobenthos as the primary food source for benthic animals has been recently reported. We investigated the microphytobenthic biomass together with light attenuation of seawater, phytoplanktonic biomass, macrobenthic density and biomass at eight stations (water depth = 5–15 m) during four cruises in 1999–2000. The increased light attenuation coefficient of the water column associated with increased concentration of the phytoplanktonic Chl-a caused a decrease in light flux that reached the seafloor. The biomass of the microphytobenthos within the upper 1 cm of the sediment, 1.9–46.5 mg Chl-a m⁻², was inversely correlated with the phytoplanktonic biomass in the overlying water column, 10.9–65.0 mg Chl-a m⁻². Thus, interception of light by phytoplankton is considered to be a main cause of the variation in the microphytobenthic biomass. The microphytobenthos biomass showed a significant positive correlation with the macrobenthic density (78–9369 ind. m⁻²) and biomass (0.4–78.8 gWW m⁻²). It appears that the increase in oxygen production by the microphytobenthos allowed macrobenthic animals to become more abundant, as a consequence of oxygenation of the organically enriched muddy sediments (14.5 ± 2.69 mg TOC g⁻¹). This study suggests that the variation in the microphytobenthic biomass is influenced by the phytoplanktonic biomass due to shading effect, and the balance between these two functional groups might affect the variability in the macrobenthic density and biomass.  相似文献   

Redating the onset of burning at Lynch's Crater (North Queensland): implications for human settlement in Australia     

C. S. M. Turney  A. P. Kershaw  P. Moss  M. I. Bird  L. K. Fifield  R. G. Cresswell  G. M. Santos  M. L. Di Tada  P. A. Hausladen  Y. Zhou 《第四纪科学杂志》2001,16(8):767-771

Lynch's Crater preserves a continuous, high‐resolution record of environmental changes in north Queensland. This record suggests a marked increase in burning that appears to be independent of any known major climatic boundaries. This increase is accompanied, or closely followed, by the virtually complete replacement of rainforest by sclerophyll vegetation. The absence of any major climatic shift associated with this increase in fire frequency therefore has been interpreted as a result of early human impact in the area. The age for this increase in burning, on the basis of conventional radiocarbon dating, was previously thought to be approximately 38 000 ¹⁴C yr BP, supporting the traditional model for human arrival in Australia at 40 000 ¹⁴C yr BP Here we have applied a more rigorous pre‐treatment and graphitisation procedure for radiocarbon dating samples from the Lynch's Crater sequence. These new dates suggest that the increase in fire frequency occurred at 45 000 ¹⁴C yr BP, supporting the alternative view that human occupation of Australia occurred by at least 45 000–55 000 cal. yr BP. Copyright © 2001 John Wiley & Sons, Ltd.  相似文献   

Upper Eocene travertine-lacustrine carbonate in the Jianchuan basin,southeastern Tibetan Plateau: Reappraisal of its origin and implication for the monsoon climate     

Aki Sakuma  Akihiro Kano  Yoshihiro Kakizaki  Ryuji Tada  Honbo Zheng 《Island Arc》2021,30(1):e12416

The Asian monsoon is one of the largest climatic systems in the world, but age of its onset has been estimated differently ranging from the late Eocene to the Quaternary. We investigated the sedimentology and stable isotopic compositions of the upper Eocene Jiuziyan Formation, a terrestrial limestone unit in the Jianchuan basin, Yunnan Province in China. This limestone formation is restricted in several localities in the central part of the basin. Previously, this has been characterized as palustrine carbonate and the transition to the sublacustrine deposit of the overlying Shuanghe Formation was interpreted as the appearance of wetter climate during the late Eocene. Our observations of macro- and microfacies revealed sedimentary fabrics indicating rapid CaCO₃ precipitation, such as dendritic calcite and calcified reed stems, which are unlikely to develop in a simple lacustrine setting. High carbonate content (mostly >90 %) and restricted distribution of the Jiuziyan limestone indicate a depositional setting spatially limited and isolated from clastic influx. These findings, together with clearly higher δ¹³C values (−0.7 ‰ to +6.9 ‰) and lower δ¹⁸O values (−14.6 ‰ to −10.5 ‰) than those of the Shuanghe Formation, indicate that the limestone was mainly travertine, carbonate formed from endogenic spring water. The elevated δ¹³C resulted from a large amount of CO₂ degassing from spring water with high pCO₂. In addition, the occurrence of centimeter-scale lamination coupled with cyclic changes in δ¹³C and δ¹⁸O is almost identical with the modern annually-laminated travertine reported from Baishuitai in northern Yunnan Province, implying comparable amplitude of seasonal temperature and precipitation changes to the record of the modern travertine at Baishuitai. Our results do not contradict the previous interpretation of late Eocene wetting and additionally suggest the existence of the late Eocene monsoon climate in the Jianchuan basin.  相似文献   

Nutrient and Phytoplankton Dynamics in Harima-Nada, Eastern Seto Inland Sea, Japan During a 35-Year Period from 1973 to 2007     

Tetsuya Nishikawa  Yutaka Hori  Satoshi Nagai  Kazutaka Miyahara  Yukinobu Nakamura  Kazuhiro Harada  Minoru Tanda  Takehiko Manabe  Kuninao Tada 《Estuaries and Coasts》2010,33(2):417-427

Long-term monitoring of water quality and phytoplankton was conducted at 19 sampling stations in Harima-Nada, eastern Seto Inland Sea, Japan for 35 years from 1973 to 2007. There were two significant long-term changes, an increase in winter water temperatures of 0.042°C year^?1, and a decrease in dissolved inorganic nitrogen (DIN) from about 10 μM in the 1970s to ~5 μM in the late 1990s due to the reduction in nutrient inputs. DIN concentrations and total phytoplankton cell density were both higher during the 1970s to the early 1980s and then exhibited a significant decrease in the mid 1980s and remained relatively constant thereafter. Diatoms were the dominant phytoplankton group (>90%) over the 35-year period, and there was a dramatic shift from Skeletonema dominance (~70%) to Chaetoceros in the mid 1980s. This shift in diatom species may be attributed to differences in the life cycle of Skeletonema and Chaetoceros and the response to the decrease in DIN concentration.  相似文献