Prevalence and diversity of norovirus genogroups I and II in Hong Kong marine waters and detection by real-time PCR

Marine waters from six sites around Hong Kong with varying levels of sewage pollution were examined for noroviruses (NoVs) by PCR cloning and sequencing of a highly-variable N-terminal region of the VP1 capsid gene, at the ORF1-ORF2 junction of NoV. Phylogenetic analysis of genogroups GI- and GII-specific PCR clones obtained from different marine sites indicated that human NoV GI.1 and GII.4 strains are the most prevalent genotypes circulating in Hong Kong waters. GI- and GII-specific TaqMan-based real-time PCR assays targeting the ORF1-ORF2 junction of NoVs were used to quantify NoV particles in marine water samples in parallel with total Escherichia coli counts which were enumerated on TBX medium. No correlation of any significance between NoV and E. coli counts was observed which highlighted the inadequacy in using E. coli as a fecal indicator to predict the level of NoVs in marine waters to protect public health.     

Effects of rotation motions on strong-motion data

Rotation motion and its effects on strong-motion data, in most cases, are much smaller than that of translational motion and have been ignored in most analyses of strong-motion data. However, recent observations from near-fault and/or extreme large ground motions suggest that these effects might be underestimated and quantitative analyses seem to be necessary for improving our understating of these effects. Rotation motion-related effects include centrifugal acceleration, the effects of gravity and effects of the rotation frame. Detailed analyses of these effects based on the observed data are unavailable in the literature. In this study, we develop a numerical algorithm for estimating the effects of rotational motion on the strong-motion data using a set of six-component ground motions and apply it to a set of rotation rate-strong motion velocity data. The data were recorded during a magnitude 6.9 earthquake. The peak value of the derived acceleration and rotation rate of this dataset are about 186 cm/s/s and 0.0026 rad/s. Numerical analyses of data gives time histories of these rotational motion-related effects. Our results show that all the rotation angles are less than 0.01°. The maximum centrifugal acceleration, effect from gravity and effect of the rotation frame are about 0.03 and 0.14 cm/s/s, respectively. Both these two effects are much smaller than the peak acceleration 186 cm/s/s. This result might have been expected because our data are not near-field and wave motions are expected to be nearly plane waves. However, it is worth noticing that the centrifugal acceleration is underestimated and a small rotational effect can cause large waveform difference in acceleration data. The waveform difference before and after the correction for rotational motion can reach 16 cm/s/s (about 10 %).     

山东区域地电场观测质量分析

对7个台的观测数据质量进行评价和分析,结果表明:郯城、菏泽、大山和陵阳地震台数据质量较好,精度较高,可为地震研究提供可靠的数据资料.     

二相随机介质有效电导率的广义混合率模型研究(英文)

广义混合率模型目前多应用于岩石的流变、杨氏模量等力学性质的研究,较少应用于多相介质岩石的有效电导率研究。本文利用三维有限元方法计算得到大量二相随机介质模型的有效电导率数据,引入广义混合率的有效电导率模型进行数据拟合,发现广义混合率模型参数J与两相介质电导率比值有关,并首次获得参数 J 与两相介质电导率比值之间的关系式,据此可以快速准确的预测(计算)任意二相介质的有效电导率,其结果较已有的随机介质模型和有效介质理论模型公式更为准确,为精细储集层评价奠定坚实基础。     

汶川地震在北京地区的形变同震响应

2008年5月12日四川汶川发生8.0级巨大地震。在这次大地震中,除压磁应力观测手段外,北京地区的钻空、倾斜、伸缩、断层、沙层、体应变等形变分值或秒值采样仪器记录到不同程度的同震响应。为了分析同震响应的表现形态及变化特征,系统搜集、整理和归纳了该地震引发的北京地区数字化同震响应信息。实际记录与分析结果表明,各类形变资料均出现不同幅度的形变震荡波,且不同仪器记震能力差别很大,验证了九五、十五和奥运保障新安装的数字化形变仪器的可靠性与灵敏性等问题。     

The Kuroshio Extension: a leading mechanism for the seasonal sea-level variability along the west coast of Japan

Sea level changes coherently along the two coasts of Japan on the seasonal timescale. Archiving, validation, and interpretation of satellite oceanographic altimetry data and ocean general circulation model for the Earth Simulator results indicate that the variation propagates clockwise from Japan’s east coast through the Tsushima Strait into the Japan/East Sea (JES) and then northward along the west coast. In this study, we hypothesize and test numerically that the sea-level variability along the west coast of Japan is remotely forced by the Kuroshio Extension (KE) off the east coast. Topographic Rossby waves and boundary Kelvin waves facilitate the connection. Our 3D Princeton Ocean Model when forced by observed wind stress reproduces well the seasonal changes in the vicinity of JES. Two additional experiments were conducted to examine the relative roles of remote forcing and local forcing. The sea-level variability inside the JES was dramatically reduced when the Tsushima Strait is blocked in one experiment. The removal of the local forcing, in another experiment, has little effect on the JES variability. Both experiments support our hypothesis that the open-ocean forcing, possibly through the KE variability, is the leading forcing mechanism for sea-level change along the west coast of Japan.     

CDMA无线传输在乌江数字地震台网的实施

无线网络通信是先进的通讯技术,利用无线网络开展的信息化应用具有显著优势,在地震观测与测震台网建设中,选用无线网络通信,组网便捷,既能实现数据传输,也能节约成本。CDMA有多种组网方式,进行高效组网,要根据不同环境来规划。简述CDMA无线传输技术在乌江数字地震台网的应用,找出影响传输质量的原因。     

Why does the Kuroshio northeast of Taiwan shift shelfward in winter?

Observations indicate that off the northeastern coast of Taiwan a branch of the Kuroshio intrudes farther northward in winter onto the shelf of the East China Sea. We demonstrate that this seasonal shift can be explained solely by winter cooling. Cooling produces downslope flux of dense shelf water that is compensated by shelfward intrusion. Parabathic isopycnals steepen eastward in winter and couple with the cross-shelf topographic slope (the “JEBAR” effect) to balance the enhanced intrusion. The downslope flow also increases vortex stretching and decreases the thickness of the inertial boundary layer, resulting in a Kuroshio that shifts closer to the shelf break.     

阴雨天气对海南数字地震台网的影响及防范

海南省夏秋为雷雨季节,日照充足,冬春两季阴雨天多,绵绵细雨。通过对各子台故障情况统计分析,掌握阴雨天气对海南数字地震台网的影响特征,并介绍一些防范措施。