Imposex in Japanese gastropods (neogastropoda and mesogastropoda): Effects of tributyltin and triphenyltin from antifouling paints     

T. Horiguchi  H. Shiraishi  M. Shimizu  S. Yamazaki  M. Morita 《Marine pollution bulletin》1995,31(4-12):402-405

In Japan, marine pollution by organotin compounds is serious and imposex is known to occur in marine gastropods. However, a detailed survey on imposex had not previously been conducted. The first country-wide survey and laboratory experiments on imposex in Japanese gastropods has now been carried out, and the results are reported herein.  相似文献   

Mesoscale Reproducibility in Regional Ocean Modelling with a Three-Dimensional Stratification Estimate Based on Aviso-Argo Data     

Yusuke Uchiyama  Ryosuke Kanki  Akiko Takano  Hidekatsu Yamazaki  Yasumasa Miyazawa 《大气与海洋》2018,56(4):212-229

ABSTRACT

For dynamically consistent, high-resolution, yet cost-effective regional oceanic downscaling modelling, an empirical three-dimensional (3D) density estimate based on publicly available datasets is utilized for the Regional Oceanic Modeling System (ROMS) with simple data assimilation (i.e., TS nudging, where TS stands for temperature and salinity). We rely on a method built upon the two-layer model to reconstruct a mesoscale 3D temperature and salinity field, referred to as Tokyo University of Marine Science and Technology (TUMSAT)-TS, using near real-time altimeter-derived dynamic height along with Argo float profiling data. The TUMSAT-TS is first validated using in situ hydrographic data, then is implemented in the Japan Coastal Ocean Predictability Experiment (JCOPE2)-ROMS downscaling system for the Kuroshio region off Japan. We explore the usability of TUMSAT-TS by carrying out three comparative simulations with temperature and salinity nudging towards the (i) TUMSAT-TS and (ii) JCOPE2-TS fields, and (iii) without the nudging. Whereas the unassimilated case fails to properly account for the Kuroshio, both datasets individually are found to help reproduce the mesoscale variability of the Kuroshio, as well as its transient paths, volume transport, associated kinetic energy (KE) and eddy KE, and seasonally varying stratification.  相似文献   

TeV γ-rays from old supernova remnants     

Ryo Yamazaki  Kazunori Kohri  Aya Bamba  Tatsuo Yoshida  Toru Tsuribe  Fumio Takahara 《Monthly notices of the Royal Astronomical Society》2006,371(4):1975-1982

We study the emission from an old supernova remnant (SNR) with an age of around 10⁵ yr and that from a giant molecular cloud (GMC) encountered by the SNR. When the SNR age is around 10⁵ yr, proton acceleration is efficient enough to emit TeV γ-rays both at the shock of the SNR and that in the GMC. The maximum energy of primarily accelerated electrons is so small that TeV γ-rays and X-rays are dominated by hadronic processes,  π⁰  -decay and synchrotron radiation from secondary electrons, respectively. However, if the SNR is older than several 10⁵ yr, there are few high-energy particles emitting TeV γ-rays because of the energy-loss effect and/or the wave-damping effect occurring at low-velocity isothermal shocks. For old SNRs or SNR–GMC interacting systems capable of generating TeV γ-ray emitting particles, we calculated the ratio of TeV γ-ray (1–10 TeV) to X-ray (2–10 keV) energy flux and found that it can be more than  ∼10²  . Such a source showing large flux ratio may be a possible origin of recently discovered unidentified TeV sources.  相似文献   

Loss Processes of Sinking Fecal Pellets of Zooplankton in the Mesopelagic Layers of the Antarctic Marginal Ice Zone     

Hidekatsu Suzuki  Hiroshi Sasaki  Mitsuo Fukuchi 《Journal of Oceanography》2003,59(6):809-818

A time-series sediment trap deployment was carried out in the marginal ice zone (MIZ) of the Antarctic Ocean (64°42′ S, 139°58′E; sea depth of 2930 m), during the austral summer. Cylindrical fecal pellets were the predominant sinking particles at 537 m in the middle of January and most of them disappeared below that depth, the loss of which were 25.3 mg C m⁻² day⁻¹ in the depth range of 537–796 m. Small-sized sinking particles other than fecal pellets increased in that depth range. Analyses of fecal pellets for remnant DNA corresponding to 16S mitochondrial RNA and 28S ribosomal RNA suggested that the large cylindrical fecal pellets at 537 m were produced by Antarctic krill (Euphausia superba) and copepods. According to the presence of the DNA associated with sinking particles, E. superba fecal pellets rapidly disappeared below 537 m, while copepod fecal pellets still remained in the mesopelagic and bathypelagic layers. Small-sized amorphous sinking particles at 537 m also contained E. superba- and copepod-derived DNA. The abundance of trap-collected copepods (Oithona spp. and Oncaea spp.) which are known to be coprophagous increased at 796 m where many fecal pellets disappeared. We suggest that those rapidly sinking pellets were fragmented by copepods with intensified coprorhexy activity (fragmentation of fecal pellets) in the mesopelagic layers, reducing their sinking rates. These smaller and slower sinking particles can be important food sources for detritivorus or coprophagous animals in mesopelagic and bathypelagic layers in the MIZ. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

Vertical profile of polycyclic aromatic hydrocarbons in a sediment core from a reservoir in Osaka City   总被引：1，自引：0，他引：1  

Miho Ishitake  Hiroshi Moriwaki  Kenshi Katahira  Osamu Yamamoto  Kenshiro Tsuruho  Hideo Yamazaki  Shusaku Yoshikawa 《Environmental Geology》2007,52(1):123-129

Concentrations of polycyclic aromatic hydrocarbons (PAHs) were measured in a dated sediment core from a reservoir at Osaka City, Southwest Japan. The sediment core consisted of deposits collected over a period of almost 70 years whose PAH content would serve as a historical record of atmospheric environment at Osaka City. Total PAH concentrations varied from 4.2 to 26 mg kg⁻¹ dry wt, and peaked in the 1940s, reflecting the occurrence of a large fire due to air attacks during World War II. The results indicated that warfare had the largest impact on atmospheric environment in Osaka City. Total PAH concentrations decreased in the post-war period except for a small peak. In the 1950s, there was a downward trend from the 1970s to the present. These trends can be ascribed to the growth of industrial activities and the regulation of atmospheric pollutant emissions, respectively.  相似文献   

Measurement of Halogenated Dicarboxylic Acids in the Arctic Aerosols at Polar Sunrise     

M. Narukawa  K. Kawamura  H. Hatsushika  K. Yamazaki  S.-M. Li  J. W. Bottenheim  K. G. Anlauf 《Journal of Atmospheric Chemistry》2003,44(3):323-335

Halogenated dicarboxylic acids, such as bromomalonic (Br-C₃), chlorosuccinic (Cl-C₄) and bromosuccinic (Br-C₄) acids, have been measured, for the first time, in the arctic aerosols during the polar sunrise experiment ALERT2000 (February to May). They were detected in the light spring, but not in the dark winter. Concentration ranges of halogenated diacids in the spring were 0.11–0.68 ng m^–3 for Br-C₃ diacid, 0.04–0.10 ng m^–3 for Cl-C₄ diacid and 0.12–0.20 ng m^–3 for Br-C₄ diacid. Those of Br-C₃ diacid increased from late April to early May, whereas Cl-C₄ diacid decreased. In contrast, Br-C₄ diacid showed maximum concentrations in the middle of the experiment. A strong negative correlation (R = –0.98) was obtained between Br-C₃ and Cl-C₄ diacids. Concentrations of methanesulfonic acid (MSA) also increased from late April to early May whereas those of Cl^– ion decreased. A strong positive correlation was found between Cl-C₄ diacid and Cl^– ion (R = 0.99) and between Br-C₃ diacid and MSA (R = 0.96). These results suggest that Br-C₃ diacid is primarily derived from marine biogenic source, whereas Cl-C₄ diacid is secondarily formed by heterogeneous reaction involving halogen chemistry on sea salt. Satellite images of sea ice concentrations and backward air mass trajectories suggest that the aerosols containing halogenated diacids were transported over the sampling sites from the Arctic Ocean covered with sea ice.  相似文献   

Estimation of the spatial distribution of ground motion parameters for two recent earthquakes in Japan   总被引：8，自引：0，他引：8  

Khosrow T. Shabestari  Fumio Yamazaki  Jun Saita  Masashi Matsuoka 《Tectonophysics》2004,390(1-4):193-204

A recent development in strong motion instrumentation in Japan provides an opportunity to collect valuable data sets, especially after moderate and large magnitude events. Gathering and modeling these data is a necessity for better understanding of regional ground motion characteristics. Estimations of the spatial distribution of earthquake ground motion plays an important role in early-stage damage assessments for both rescue operations by disaster management agencies as well as damage studies of urban structures. Subsurface geology layers and local soil conditions lead to soil amplification that contributes to the estimated ground motion parameters of the surface. We present a case study of the applicability of the nationally proposed GIS-based soil amplification ratios [J. Soil Dyn. Earthqu. Eng. 19 (2000) 41–53] to the October 6, 2000 Tottori-ken Seibu (western Tottori Prefecture) and the March 24, 2001 Geiyo earthquakes in Japan. First, ground motion values were converted to those at a hypothetical ground base-rock level (outcrop) using an amplification ratio for each 1×1 km area, based on geomorphological and subsurface geology information. Then a Kriging method, assuming an attenuation relationship at the base-rock as a trend component, is applied. Finally, the spatial distribution of ground motion at ground surface is obtained by applying GIS-based amplification factors for the entire region. The correlation between the observed and estimated ground motion values is reasonable for both earthquakes. Thus, the proposed method is applicable in near real-time early-damage assessments and seismic hazard studies in Japan.  相似文献   

A mixed model for earthquake interevent times     

Abdelhak Talbi  Fumio Yamazaki 《Journal of Seismology》2010,14(2):289-307

A mixed model is proposed to fit earthquake interevent time distribution. In this model, the whole distribution is constructed by mixing the distribution of clustered seismicity, with a suitable distribution of background seismicity. Namely, the fit is tested assuming a clustered seismicity component modeled by a non-homogeneous Poisson process and a background component modeled using different hypothetical models (exponential, gamma and Weibull). For southern California, Japan, and Turkey, the best fit is found when a Weibull distribution is implemented as a model for background seismicity. Our study uses earthquake random sampling method we introduced recently. It is performed here to account for space–time clustering of earthquakes at different distances from a given source and to increase the number of samples used to estimate earthquake interevent time distribution and its power law scaling. For Japan, the contribution of clustered pairs of events to the whole distribution is analyzed for different magnitude cutoffs, m _c, and different time periods. The results show that power laws are mainly produced by the dominance of correlated pairs at small and long time ranges. In particular, both power laws, observed at short and long time ranges, can be attributed to time–space clustering revealed by the standard Gardner and Knopoff’s declustering windows.  相似文献   

Generation of 3D virtual geographic environment based on laser scanning technique     

DUJie CHENXiaoyong FumioYamazaki 《地球空间信息科学学报》2003,6(3):37-42

This paper demonstrates an experiment on the generation of 3D virtual geographic environment on the basis of experimental flight laser scan-ning data by a set of algorithms and methods that were developed to auto-matically interpret range images for extracting geo-spatial features and then to reconstruct geo-objects. The algorithms and methods for the inter-pretation and modeling of laser scanner data include triangulated-irregular-net- work (TIN)-based range image inter- polation; mathematical-morphology (MM)-based range image filtering,feature extraction and range image segmentation, feature generalization and optimization, 3D objects recon-struction and modeling; computer-graphics (CG)-based visualization and animation of geographic virtual reality environment.  相似文献   

Tail emission of prompt gamma-ray burst jets     

Ryo Yamazaki  Kenji Toma  Kunihito Ioka  Takashi Nakamura 《Monthly notices of the Royal Astronomical Society》2006,369(1):311-316

Tail emission of the prompt gamma-ray burst (GRB) is discussed using a multiple emitting sub-shell (inhomogeneous jet, sub-jets or mini-jets) model, where the whole GRB jet consists of many emitting sub-shells. One may expect that such a jet with angular inhomogeneity should produce spiky tail emission. However, we found that the tail is not spiky but is decaying roughly monotonically. The global decay slope of the tail is not so much affected by the local angular inhomogeneity but affected by the global sub-shell energy distribution. The fact that steepening GRB tail breaks appeared in some events prefers the structured jets. If the angular size of the emitting sub-shell is around 0.01–0.02 rad, some bumps or fluctuations appear in the tail emission observed frequently in long GRBs. If the parameter differences of sub-shell properties are large, the tail has frequent changes of the temporal slope observed in a few bursts. Therefore, the multiple emitting sub-shell model has the advantage of explaining the small-scale structure in the observed rapid decay phase.  相似文献