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Phylogenetic diversity and phenotypic characterization of cultivable bacterioplankton isolated from polar oceans 总被引:1,自引:0,他引:1
A set of 27 marine planktonic bacteria isolated from the polar regions was characterized by 16S rDNA sequencing and physiological and biochemical testing. More than half of these bacteria were positive for caseinase, gelatinase and 13-glucosidase, and could utilize glucose, maltose or malic acid as carbon source for cell growth. Twelve isolates expressed nitrate reduction activities. Except for one antarctic isolate BSwlO175 belonging to Actinobacteria phylum, these isolates were classified as γ-Proteobacteria, suggesting that γ-Proteobacteria dominated in cultivable marine bacterioplankton at both poles. Genus Pseudoalteromonas was the predominant group in the Chukchi Sea and the Bering Sea, and genus ShewaneUa dominated in cultivable bacterioplankton in the Prydz Bay. With sequence similarities above 97%, genus Psychrobacter was found at both poles. These 27 isolates were psychrotolerant, and significant 16S rDNA sequence similarities were found not only between arctic and antarctic marine bacteria ( 〉 99% ), but also between polar marine bacteria and bacteria from other aquatic environments ( ≥ 98.8% ), including temperate ocean, deep sea, pond and lake, suggesting that in the polar oceans less temperature-sensitive bacteria may be cosmopolitan and have a bipolar, even global, distribution at the species level. 相似文献
133.
Significant wave height(SWH) can be computed from the returning waveform of radar altimeter, this parameter is only raw estimates if it does not calibrate. But accurate calibration is important for all applications, especially for climate studies. HY-2a altimeter has been operational since April 2012 and its products are available to the scientific community. In this work, SWH data from HY-2A altimeters are calibrated against in situ buoy data from the National Data Buoy Center(NDBC), Distinguished from previous calibration studies which generally regarded buoy data as "truth", the work of calibration for HY-2A altimeter wave data against in situ buoys was applied a more sophisticated statistical technique—the total least squares(TLS) method which can take into account errors in both variables. We present calibration results for HY-2A radar altimeter measurement of wave height against NDBC buoys. In addition, cross-calibration for HY-2A and Jason-2 wave data are talked over and the result is given. 相似文献
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An efficient algorithm for identifying pulse‐like ground motions based on significant velocity half‐cycles 下载免费PDF全文
Ground motions with strong velocity pulses are of particular interest to structural earthquake engineers because they have the potential to impose extreme seismic demands on structures. Accurate classification of records is essential in several earthquake engineering fields where pulse‐like ground motions should be distinguished from nonpulse‐like records, such as probabilistic seismic hazard analysis and seismic risk assessment of structures. This study proposes an effective method to identify pulse‐like ground motions having single, multiple, or irregular pulses. To effectively characterize the intrinsic pulse‐like features, the concept of an energy‐based significant velocity half‐cycle, which is visually identifiable, is first presented. Ground motions are classified into 6 categories according to the number of significant half‐cycles in the velocity time series. The pulse energy ratio is used as an indicator for quantitative identification, and then the energy threshold values for each type of ground motions are determined. Comprehensive comparisons of the proposed approach with 4 benchmark identification methods are conducted, and the results indicate that the methodology presented in this study can more accurately and efficiently distinguish pulse‐like and nonpulse‐like ground motions. Also presented are some insights into the reasons why many pulse‐like ground motions are not detected successfully by each of the benchmark methods. 相似文献
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利用COAWST数值模式就琼州海峡内潮流场对冬季风浪场的影响进行了研究。经实测数据验证,模型可较好的刻画海峡内的强潮流场。选定东、西向最大潮流时刻为典型案例分别就水位场及潮流场对波浪场的作用展开探讨。在琼州海峡东口处,西向最大潮流时刻下的正水位场增加了承载波浪运动的有效水深,有利于波浪能量的西向传播,进而使得当地有效波高增加。东、西向最大潮流均有利于琼州海峡东口处有效波高的增大,但前者主要通过流致辐聚效应实现,而后者主要经由流致波数位移生效。通过流致折射作用,东向(西向)最大潮流可在海峡中轴线以北的海区引起谱峰波向的逆时针(顺时针)旋转,而在以南的海区触发顺时针(逆时针)旋转。 相似文献
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基于显著区域提取技术,对复杂的视频镜头中动静结合显著图的提取技术进行了改进,提出由动态模型和静态模型两个特征要素作为线索提取动静结合的提取方法。方法对复杂运动镜头下运动特征的选择敏感度较高,实验验证表明,提出的动态模型和静态模型以自适应权重增减的融合方式得到的动静结合显著图与以往相比,精准度较高,也更接近于人类视觉机制的选择。 相似文献
139.
有效波高是海洋动力环境的主要参数,针对现有岸基双天线GNSS-R有效波高反演方法必须使用专用型接收机,以及相关测站布设较少、数据获取困难等限制,本文提出了一种利用普通单天线测量型GNSS接收机的GNSS-IR数据反演有效波高的方法。首先,利用NARX回归神经网络构建潮高反演误差与有效波高大小之间的相关模型,并给出了从数据选取、数据集制作到反演模型构建的相关流程与方法。然后,使用斯坦福大学哈勃肯斯海洋实验站中P231站两年的数据,开展了基于NARX回归神经网络的岸基单天线GNSS-IR有效波高反演模型试验。试验结果表明,该模型适用于0.1~2.5 m (即二~四级海况之间)范围内有效波高的反演应用,反演有效波高的MSE最小为0.01 m。 相似文献
140.
永久散射体雷达干涉(PSI)已被广泛应用于城市缓慢沉降监测,但针对显著性地表沉降监测及PSI适用性的探讨较少。本文选取天津市与廊坊市城郊结合部的典型工业化城镇为研究区,分别以2007至2010年间的23幅L波段(23.6 cm)ALOS PALSAR影像和2007至2009年间的23幅C波段(5.6 cm)ENVISAT ASAR影像为数据源,使用基于相位空间相关性分析的PSI方法进行时空沉降提取,并对两个平台的结果进行对比分析和交叉验证。在此基础上,结合长短波SAR对沉降敏感性不同的特征探讨该PSI方法应用于显著沉降解算的可靠性,并结合地质条件及地下水开采信息对实验区沉降的时空分布进行深入分析和解释。研究表明,两平台的沉降结果十分吻合,在沉降漏斗区二者均方根误差(RMSE)为6.5 mm/a;实验区地表沉降呈现出显著的非均匀性,最大沉降速率超过200 mm/a,造成严重沉降的主要原因为地下水的大量开采;证实了PSI方法在显著地表沉降监测方面的有效性和可靠性。 相似文献