Encystment and excystment of <Emphasis Type="Italic">Gyrodinium instriatum</Emphasis> Freudenthal et Lee     

Tomoyuki Shikata  Sou Nagasoe  Tadashi Matsubara  Yasuhiro Yamasaki  Yohei Shimasaki  Yuji Oshima  Takuji Uchida  Ian R. Jenkinson  Tsuneo Honjo 《Journal of Oceanography》2008,64(3):355-365

In the present study, we have investigated the conditions influencing encystment and excystment in the dinoflagellate Gyrodinium instriatum under laboratory conditions. We incubated G. instriatum in modified whole SWM-3 culture medium and in versions of modified SWM-3 from which NO₃ ⁻, PO₄ ³⁻, NO₃ ⁻ + PO₄ ³⁻, or Si had been omitted and observed encystment. Percentage encystment was high in the media without N and without P, while the percentage encystment in the medium lacking both N and P was highest. Moreover, to investigate N or P concentration which induced the encystment, Gyrodinium instriatum was also incubated in media with different concentrations of inorganic N and P; the concentrations of NO₂ ⁻ + NO₃ ⁻ and PO₄ ³⁻ were measured over time. The precursors of cysts appeared within 2 or 3 days of a decrease in NO₂ ⁻ + NO₃ ⁻ or PO₄ ³⁻ concentration to values lower than 1 μM or 0.2 μM, respectively. When cysts produced in the laboratory were incubated, we observed excystment after 8–37 days, without a mandatory period of darkness or low temperature. We incubated cysts collected from nature at different temperatures or in the dark or light and observed excystments. Natural cysts excysted at temperatures from 10 to 30°C, in both light and dark, but excystment was delayed at low temperatures. These studies indicate that G. instriatum encysts in low N or P concentration and excysts over a wide temperature range, regardless of light conditions, after short dormancy periods.  相似文献   

EO-1 Hyperion高光谱数据的质量评价   总被引：4，自引：0，他引：4  

周雨霁  田庆久 《地球信息科学学报》2008,10(5):678-683

本文以影像的客观评价方法对扬州地区一景Hyperion影像的L1R数据进行质量评价。主要采用辐射精度、信息量、清晰度、信噪比等指标对图像质量进行分析,经过评价认为,影像获取时受到成像环境和天气的影响,可用波段数量可能产生一定范围的浮动。本文的影像存在44个未定标波段,25个受水汽影响波段,而SWIR130以后的波段中存在大量噪声。影像信息主要集中于VNIR和SWIR波长较短范围的约94个波段内,该范围内影像质量较高,能发挥高光谱分辨率优势,并为正确还原光谱信息提供可能。影像数据中存在的条带现象和辐射畸变经过一定处理去除后,在农业调查、监测、管理,森林覆盖、灾害预警,地质调查,找油以及海洋水色研究等领域将有良好的应用前景。  相似文献   

近断层脉冲型地震动的模拟方法   总被引：12，自引：1，他引：11       下载免费PDF全文

田玉基  杨庆山  卢明奇 《地震学报》2007,29(1):77-84

近断层地震动的向前方向性效应和永久地面位移效应导致其速度时程表现为长周期、大峰值的速度脉冲,其位移时程表现为阶跃型脉冲. 针对这些特点,同时考虑向前方向性效应和永久地面位移效应,提出了一种简单的、连续函数形式表达的等效速度脉冲模型. 在该模型中,包含描述速度脉冲周期、峰值和形状的5个待定参数,方便了实际脉冲型地震记录的拟合及模拟. 等效速度脉冲模型只包含单一的频率成分,不能反映脉冲型地震记录的高频成分. 根据对11次地震28条地震记录的分析, 速度脉冲的频率一般小于1Hz. 因此, 在模拟脉冲型地震记录的方法中,分别模拟低频脉冲成分和高频成分,并将两者叠加生成近断层脉冲型地震动的模拟时程.   相似文献   

Phase relations in the carbon-saturated C–Mg–Fe–Si–O system and C and Si solubility in liquid Fe at high pressure and temperature: implications for planetary interiors     

Suguru Takahashi  Eiji Ohtani  Hidenori Terasaki  Yoshinori Ito  Yuki Shibazaki  Miho Ishii  Ken-ichi Funakoshi  Yuji Higo 《Physics and Chemistry of Minerals》2013,40(8):647-657

The phase and melting relations of the C-saturated C–Mg–Fe–Si–O system were investigated at high pressure and temperature to understand the role of carbon in the structure of the Earth, terrestrial planets, and carbon-enriched extraterrestrial planets. The phase relations were studied using two types of experiments at 4 GPa: analyses of recovered samples and in situ X-ray diffractions. Our experiments revealed that the composition of metallic iron melts changes from a C-rich composition with up to about 5 wt.% C under oxidizing conditions (ΔIW = ?1.7 to ?1.2, where ΔIW is the deviation of the oxygen fugacity (fO₂) from an iron-wüstite (IW) buffer) to a C-depleted composition with 21 wt.% Si under reducing conditions (ΔIW < ?3.3) at 4 GPa and 1,873 K. SiC grains also coexisted with the Fe–Si melt under the most reducing conditions. The solubility of C in liquid Fe increased with increasing fO₂, whereas the solubility of Si decreased with increasing fO₂. The carbon-bearing phases were graphite, Fe₃C, SiC, and Fe alloy melt (Fe–C or Fe–Si–C melts) under the redox conditions applied at 4 GPa, but carbonate was not observed under our experimental conditions. The phase relations observed in this study can be applicable to the Earth and other planets. In hypothetical reducing carbon planets (ΔIW < ?6.2), graphite/diamond and/or SiC exist in the mantle, whereas the core would be an Fe–Si alloy containing very small amount of C even in the carbon-enriched planets. The mutually exclusive nature of C and Si may be important also for considering the light elements of the Earth’s core.  相似文献   

Impact of land-use changes on snow in a forested region with heavy snowfall in Hokkaido,Japan     

Kazuyoshi Suzuki  Yuji Kodama  Taro Nakai  Glen E. Liston  Kazukiyo Yamamoto  Tetsuo Ohata 《水文科学杂志》2013,58(3):443-467

Abstract

We simulated snow processes in a forested region with heavy snowfall in Japan, and evaluated both the regional-scale snow distribution and the potential impact of land-use changes on the snow cover and water balances over the entire domain. SnowModel reproduced the snow processes at open and forested sites, which were confirmed by snow water equivalent (SWE) measurements at two intensive observation sites and snow depth measurements at the Automated Meteorological Data Acquisition System sites. SnowModel also reproduced the observed snow distribution (from the MODIS snow cover data) over the simulation domain during thaw. The observed SWE was less at the forested site than at the open site. The SnowModel simulations showed that this difference was caused mainly by differences in sublimation. The type of land use changed the maximum SWE, onset and duration of snowmelt, and the daily snowmelt rate due to canopy snow interception.

Citation Suzuki, K., Kodama, Y., Nakai, T., Liston, G. E., Yamamoto, K., Ohata, T., Ishii, Y., Sumida, A., Hara, T. & Ohta, T. (2011) Impact of land-use changes in a forested region with heavy snowfall in Hokkaido, Japan. Hydrol. Sci. J. 56(3), 443–467.  相似文献   

Mesozoic detrital zircon U‐Pb ages of modern river sediments in Korea: implications for migration of arc magmatism in the Mesozoic East Asian continental margin     

Taejin Choi  Yong Il Lee  Yuji Orihashi 《地学学报》2012,24(2):156-165

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Jumping mechanisms of Trojan asteroids in the planar restricted three- and four-body problems     

Kenta Oshima  Tomohiro Yanao 《Celestial Mechanics and Dynamical Astronomy》2015,122(1):53-74

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Tributyltin in blood of marine fish collected from a coastal area of northern Kyushu, Japan     

Miki S  Ikeda K  Oba Y  Satone H  Honda M  Shimasaki Y  Onikura N  Arakawa O  Oshima Y 《Marine pollution bulletin》2011,62(11):2533-2536

We investigated levels of the pollutant tributyltin (TBT) in blood of pufferfishes (six species), Japanese sea perch, red sea bream, Japanese common goby, Japanese flounder, rockfish, conger eel, and sea mullet collected off the coast of northern Kyushu, Japan. We found considerable levels of TBT (1.4-190 ng/mL) accumulated in the blood of these fish. Blood TBT concentrations were 1.3-22.5 times liver concentrations and 4.9-78 times muscle concentrations, except in conger eel and mullet. We detected TBT (16-111 ng/mL-blood) in the plasma of the fine-patterned puffer (Takifugupoecilonotus) year-round, without any apparent seasonal trend. These results suggest that fish inhabiting coastal areas of Kyushu, Japan, continue to be contaminated with TBT.  相似文献   

Mineralogic investigation into occurrence of high uranium well waters in upstate South Carolina, USA     

Richard Warner  Jason Meadows  Scott Sojda  Van PriceTom Temples  Yuji AraiChris Fleisher  Bruce CrawfordPeter Stone 《Applied Geochemistry》2011,26(5):777-788

High levels of U (up to 5570 μg/L) have been discovered in well waters near Simpsonville, South Carolina, USA. In order to characterize the mineralogical source of the U and possible structural controls on its presence, a deep (214 m) well was cored adjacent to one of the enriched wells. The highest gamma-ray emissions in the recovered core occur in coarse biotite granite at a depth just below 52 m. A slickenlined fault plane at 48.6 m and narrow pegmatite layers at depths of 113, 203 and 207 m also yield high gamma-ray counts. Thin sections were made from the above materials and along several subvertical healed fractures. Uraninite and coffinite are the principal U-rich minerals in the core. Other U-bearing minerals include thorite and thorogummite, monazite, zircon and allanite. Primary uraninite occurs in the biotite granite and in pegmatite layers. Secondary coffinite is present as tiny (<5 μm) crystals dispersed along fractures in the granite and pegmatites. Coffinite also occurs along the slickenlined fault plane, where it is associated with calcite and calcic zeolite and also replaces allanite. Coffinite lacks radiogenic Pb, hence is considerably younger than the uraninite.Dissolution of partially oxidized Ca-rich uraninite occurring in the surficial biotite granite (or secondary coffinite in fracture zones) is likely the main source for the current high levels of U in nearby area wells. The high-U well waters have a carbonate signature, consistent with pervasive calcite vein mineralization in the core. Aqueous speciation calculations suggest U transport as an uranyl (U⁶⁺) hydroxyl-carbonate complex. Later reduction resulted in secondary precipitation along fractures as a U⁴⁺ mineral (i.e., coffinite).  相似文献   

Thermochronology of the PoSen complex,northern Vietnam: Implications for tectonic evolution in SE Asia     

Pei-Ling Wang  Ching-Hua Lo  Ching-Ying Lan  Sun-Lin Chung  Tung-Yi Lee  Tran Ngoc Nam  Yuji Sano 《Journal of Asian Earth Sciences》2011,40(5):1044-1055

The PoSen complex, located closely adjacent to the southwestern margin of the Red River shear zone represents the uplifted basement of north Vietnam and may record the motion of the shear zone. However, its thermochronological history has not been fully examined yet. Here we applied U–Pb and ⁴⁰Ar/³⁹Ar dating methods to reveal its thermochronological history. U–Pb analysis of composite zircon grains by TIMS yielded an average age of 760 ± 25 Ma, clustering on the concordia line. Twelve SHRIMP U–Pb analyses also yielded a consistent result of 751 ± 7 Ma. Along with the geochemical features, the U–Pb dating results suggest the PoSen complex was a late Proterozoic magmatic complex, which could correspond to the Chengjiang orogeny, a widespread thermal event in southwest China. Results of ⁴⁰Ar/³⁹Ar dating of micas and K-feldspars were in the range of 36–30 Ma, revealing a rapid cooling and exhumation history of the PoSen complex during the late Paleogene. The time span of cooling and exhumation of the PoSen complex is slightly older than the main cooling phases of the Ailao Shan–Red River (ASRR) metamorphic massifs (28–17 Ma), but is synchronous with the early igneous activity stage in the eastern Indo-Asian collision zone of southeast China and north Vietnam. Owing to the ongoing debate about the initiation and offset of the ASRR shear zone, the tectonic force for the late Paleogene cooling of the PoSen complex is still inconclusive. The rapid exhumation of the PoSen complex could be in response to either the detachment of the Neo-Tethyan slab or a transpressional phase of continental subduction along the ASRR shear system in the eastern Indo-Asian collision zone.  相似文献