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121.
J. Akai A. Kanekiyo N. Hishida M. Ogawa T. Naganuma H. Fukuhara H.N. Anawar 《Applied Geochemistry》2008
Arsenic release experiments using natural indigenous microbial assemblages and natural sediment samples in Bangladesh have been performed. The As release appears to be facilitated by moderate organic input. Addition of some nutrients caused reducing conditions, which may generate the appropriate environment for Fe-reducing bacteria to become active. Detailed cellular phospholipid fatty acid (PLFA) analysis suggests the presence of SO4-reducing and Fe-reducing bacteria in the sediments. These Fe-reducing bacteria may serve as the agents catalyzing As release in the organic-rich sediments. 16S rDNA analysis of one cultured sample suggests the presence of clostridia, some of which are known to mediate Fe reduction. Based on new PLFA analyses, it is proposed that combined microbial processes of SO4 reduction to generate anaerobic conditions and Fe reduction to co-reduce As are important biogeochemical factors for As release in the Bangladesh sediments. 相似文献
122.
Discovery of local topics by using latent spatio-temporal relationships in geo-social media 总被引:1,自引:0,他引:1
Kyoung-Sook Kim Isao Kojima Hirotaka Ogawa 《International journal of geographical information science》2016,30(9):1899-1922
ABSTRACTSocial networks have played a crucial role as information channels for people to understanding their daily lives beyond merely being communication tools. In particular, coupling social networks with geographic location has boosted the worth of social media to not only enable comprehension of the effects of natural phenomena such as global warming and disasters, but also the social patterns of human societies. However, the high rate of social data generation and the large amounts of noisy data makes it difficult to directly apply social media to decision-making processes. This article proposes a new system of analyzing the spatio-temporal patterns of social phenomena in real time and the discovery of local topics based on their latent spatio-temporal relationships. We will first describe a model that represents the local patterns of populations of geo-tagged social media. We will then define a local topic whose keywords share a region in space and time and present a system implementation based on existing open source technologies. We evaluated the model of local topics with several ways of visualization in experiments and demonstrated a certain social pattern from a dataset of daily Twitter streams. The results obtained from experiments revealed certain keywords had a strong spatio-temporal proximity even though they did not occur in the same message. 相似文献
123.
Insight into nitrous oxide production processes in the western North Pacific based on a marine ecosystem isotopomer model 总被引:2,自引:0,他引:2
124.
125.
A channelised long run-out debris slide triggered by the Noto Hanto Earthquake in 2007, Japan 总被引:2,自引:1,他引:1
Yasuhiko Okada Hirotaka Ochiai Ushio Kurokawa Yasuhiro Ogawa Shiho Asano 《Landslides》2008,5(2):235-239
A strong earthquake (M
J 6.9, M
W 6.6–6.7) at about 11 km depth hit the western shore of the Noto Peninsula on Honshu, Japan, at about 00:42 coordinated universal
time (9:42 a.m. local time) on 25 March 2007 (the Noto Hanto Earthquake in 2007). The earthquake triggered only 61 landslides, with most
traveling short distances. It caused one long run-out landslide in the Nakanoya district of Monzen town, Wajima city, Ishikawa
Prefecture, when a portion of a deep-seated landslide transformed into a moderate debris slide down a channel. The rock slide
occurred on a south-facing convex-shaped slope on a small spur where earthquake ground shaking likely was strongly amplified
by topography. A portion of the rock slide reached a small channel floored by materials containing abundant groundwater. Constant-volume
box-shear tests on normally consolidated saturated specimens revealed that the apparent angle of internal friction of the
channel-floor material was 33–36° at 10-mm shear displacement and did not show much decrease in effective normal stress during
shearing. In situ rock-sliding testing on the exposed channel materials showed a low kinetic-friction angle of about 21°.
We suggest that an unsaturated portion of the rock slide slid down the channel, with sliding between the rock-slide mass and
the channel floor. Because the slope angle of the travel path nearly equaled the kinetic-friction angle, the unsaturated rock
slide mass may have traveled at a moderately slow speed, or it might have decelerated and accelerated. Slow speed is supported
by accounts from local residents that suggest movement of debris continued for 3 days after the main shock. 相似文献
126.
This paper analyzes daily variations in the occurrences of pelagic fishes and zooplankters on a small regional scale. The data used are based on daily observations repeated at 24h intervals during 6 days from 16 to 21, September, 1971, in coastal waters close to Esaki, a fishing port in the southwestern part of the Japan Sea (Yamaguchi Prefecture). The observations comprised acoustic surveys of the fish population, zooplankton sampling with a net, and Secchi disc readings, for evaluating relationships between the abundances of pelagic fishes and their food, as well as alternations in water masses. No clear correlation between pelagic fishes and their food, copepods, within a short time period was observed; fish population continued to decrease with eastward movements of fish schools although the abundances of copepods remained at almost the same level during the observations. Patterns of changes in both settled volumes of plankton and transparencies evidently suggested the occurrence of alternations in water masses. Pelagic fish schools proved to move in company with the transition of water masses. 相似文献
127.
Tatsuji Kato Toshihiro Omodaka Mitsumi Fujishita Kin-Aki Kawabata Hideo Ogawa 《Solar physics》1982,78(1):137-140
Interferometer observation of a behind-the-limb flare on 7 September, 1977, at 35 GHz ( = 8.6 mm) shows that the microwave non-thermal radio source of the burst is located in the coronal region at the height higher than 7000 km above the photosphere and rises gradually with the velocity of about 30 km s-1. 相似文献
128.
129.
Yoshimasa Tanaka Atsuki Shinbori Tomoaki Hori Yukinobu Koyama Shuji Abe Norio Umemura Yuka Sato Manabu Yagi Satoru UeNo Akiyo Yatagai Yasunobu Ogawa Yoshizumi Miyoshi 《极地研究(英文版)》2013,(4):231-240
To comprehensively understand the Arctic and Antarctic upper atmosphere, it is often crucial to analyze various data that are obtained from many regions. Infrastructure that promotes such interdisciplinary studies on the upper atmosphere has been developed by a Japanese inter-university project called the Inter-university Upper atmosphere Global Observation Network (1UGONET). The objective of this paper is to describe the infrastructure and tools developed by IUGONET. We focus on the data analysis software. It is written in Interactive Data Language (IDL) and is a plug-in for the THEMIS Data Analysis Software suite (TDAS), which is a set of IDL libraries used to visualize and analyze satellite- and ground-based data. We present plots of upper atmospheric data provided by IUGONET as examples of applications, and verify the usefulness of the software in the study of polar science. We discuss IUGONET's new and unique developments, i.e., an executable file of TDAS that can run on the IDL Virtual Machine, IDL routines to retrieve metadata from the IUGONET database, and an archive of 3-D simulation data that uses the Common Data Format so that it can easily be used with TDAS. 相似文献
130.
Numerical models are systematically presented for time-dependent thermal convection of Newtonian fluid with strongly temperature-dependent viscosity in a two-dimensional rectangular box of aspect ratio 3 at various values of the Rayleigh number Rab defined with viscosity at the bottom boundary up to 1.6×108 and the viscosity contrast across the box rη up to 108. We found that there are two different series of bifurcations that take place as rη increases. One series of bifurcations causes changes in the behavior of the thermal boundary layer along the surface boundary from small-viscosity-contrast (SVC) mode, through transitional (TR) mode, to stagnant-lid (ST) mode, or from SVC mode directly to ST mode, depending on Rab. Another series of bifurcations causes changes in the aspect ratio of convection cells; convection with an elongated cell can take place at moderate rη (103–105.5 at Rab=6×106), while only convection of aspect ratio close to 1 takes place at small rη and large rη. The parameter range of rη and Rab for elongated-cell convection overlaps the parameter range for SVC and ST modes and include the entire parameter range for TR mode. In the elongated-ST regime, the lid of highly viscous fluid along the top boundary is not literally ‘stagnant’ but can horizontally move at a velocity high enough to induce a convection cell with aspect ratio much larger than 1. 相似文献