2022年6月1日四川芦山MS6.1地震的发震构造与力学机制探讨

2022年6月1日17时00分08秒（北京时间）四川雅安市芦山县发生M_S6.1地震,此次地震是继2008年汶川M_S8.0、2013年芦山M_S7.0地震后发生在龙门山断裂带的又一显著地震,与后者在空间上仅相距9 km.为揭示此次地震的发震构造特征及其与2013年芦山M_S7.0地震的关系,进而理解龙门山断裂带强震孕育动力学过程与地震危险性,本文采用CAP全波形反演方法计算了芦山M_S6.1地震的震源机制解,利用多阶段定位法对2013年芦山M_S7.0地震以来余震区地震进行了精确定位,并基于库仑应力讨论两次地震的应力触发关系.结果显示,芦山M_S6.1地震的震源机制解为：节面Ⅰ的走向、倾角和滑动角分别为221°、40°和105°;节面Ⅱ的参数为22°、52°和78°,矩心深度14 km,震源机制断层面解呈现一组与龙门山断裂带性质接近的节面.反演给出的P轴方位角为120°,倾角为6°,反映了此次地震主要受NWW-SEE向水平挤压应力作用,与龙门山断裂带南段背景构造应力场一致.地震精定位结果显示芦山M_S6.1地震序列发生在2013年芦山M_S7.0地震发震断层北西侧的一条倾向南东的反冲断层上,据此可判断震源机制解的节面Ⅱ为发震断层面.在此基础上,通过指定发震与接收断层,计算获得2013年芦山M_S7.0地震对此次M_S6.1地震所在断层的最大库仑应力加载值可达1.5 MPa,说明前者对后者有显著的触发作用.

     

黄土边坡植物根系固土护坡效应研究

黄土高原生态环境脆弱,且随着人类工程活动日益频繁,黄土滑坡等地质灾害问题也日益严重。植物护坡是恢复黄土边坡生态和防治黄土边坡地质灾害的有效手段。本文基于延安地区黄土边坡调查,通过植物科属分布及密度,及其在边坡植被群落结构中的生长特征等分析,查明植物生长特征与边坡生境的相关联系,筛选适宜当地环境的护坡树种;通过原位试验,分析植物根系固土护坡效应;最后在总结上述研究成果的基础上,提出了该地区适宜的护坡植物,为陕北地区黄土边坡植物防护设计提供了理论依据。本研究成果能促进植物在西北黄土地区的工程应用,为西北黄土边坡复合型生态防护技术提供指导。     

一种基于贝叶斯理论的区域斜坡稳定性评价模型

本文结合滑坡物理模型和统计模型的优点,针对小流域滑坡稳定性分析,建立了一种基于贝叶斯理论的区域斜坡稳定性评价模型。该模型主要采用灾害自身信息来修正原始模型中的参数,解决了区域稳定性评价中参数难以确定的问题。该方法首先设定模型的初始参数分布,然后利用采样点雨前和雨后稳定性不同的信息建立验证方程,再根据马尔科夫链蒙特卡罗模拟和贝叶斯方法确定最终的参数分布,进而得出区域稳定性分布。应用该模型对福建省蔡源小流域的6 13滑坡群发性事件进行分析。结果显示,蔡源小流域地区的无量纲黏聚系数C为0.028,有效摩擦角为16.7,土壤的导水系数T和降雨量q的比值为529.026m,可能不稳定地区和不稳定地区达到76.0%。该模型利用历史灾害数据自动模拟出合适的参数,对区域滑坡稳定性评价具有重要意义。     

Detection of a high-confidence quasi-periodic oscillation in radio light curve of the high redshift FSRQ PKS J0805–0111

In this work,we have searched for quasi-periodic oscillations(QPOs)in the 15 GHz light curve of the FSRQ PKS J0805-0111 monitored by the Owens Valley Radio Observatory(OVRO)40 m telescope during the period from 2008 January 9 to 2019 May 9,using the weighted wavelet Z-transform(WWZ)and the Lomb-Scargle Periodogram(LSP)techniques.This is the first time to search for a periodic radio signal in the FSRQ PKS J0805-0111 by these two methods.Both methods consistently reveal a repeating signal with a periodicity of 3.38±0.8 yr(>99.7%confidence level).In order to determine the significance of the periods,the false alarm probability method was applied,and a large number of Monte Carlo simulations were performed.As possible explanations,we discuss a number of scenarios including the thermal instability of thin disks scenario,the spiral jet scenario and the binary supermassive black hole scenario.We expect that the binary black hole scenario,where the QPO is caused by the precession of binary black holes,is the most likely explanation.FSRQ PKS J0805-0111 thus could be a good binary black hole candidate.In the binary black hole scenario,the distance between the primary black hole and the secondary black hole is about 1.71×10¹⁶ cm.     

Research activities on land-use/cover change in the past ten years in China using space technology

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Localization and dynamic expression of a 27.8 kDa receptor protein for lymphocystis disease virus infection in sea bass (<Emphasis Type="Italic">Lateolabrax japonicus</Emphasis>) tissues

Lymphocystis disease virus (LCDV) infects target cells by attaching to a 27.8 kDa receptor (27.8R) protein in flounder Paralichthys olivaceus, and anti-27.8R monoclonal antibodies (MAbs) have been developed. However, the 27.8R existence in tissues of sea bass (Lateolabrax japonicus) and its role in LCDV infection have remained unclear. In this study, the results of western blotting demonstrated that the same 27.8R was shared by flounder and sea bass. LCDV-free sea bass individuals were intramuscularly injected with LCDV, and viral copies were detected in tissues from 3 h post infection and showed a time-dependent increase during 9 days infection. Distribution and synthesis of 27.8R in sea bass tissues were investigated by using anti-27.8R MAbs as probes. It was found that 27.8R was distributed in all the tested tissues. The levels of 27.8R protein were highest in gill and skin, then a bit lowly in stomach, head kidney and heart, followed by spleen, intestine, blood cells, gonad and liver, and least in kidney and brain in healthy sea bass. Upon LCDV infection, 27.8R synthesis was up-regulated in each tissue, and higher in the tissues with higher LCDV copies. The 27.8R and LCDV were detected in some peripheral blood leukocytes but not in red blood cells. These results suggested that 27.8R was widely distributed in sea bass tissues, and it served as a receptor and correlated with tissue tropism of LCDV infection. Furthermore, leukocytes had the potential of being a LCDV carrier and were responsible for a systemic infection of LCDV in sea bass.     

土地招拍挂流标流拍成因及对策

近年来,土地出让招、拍、挂方式的施行,为广大用地者提供一个公开、公平、公正的竞争环境,活跃了土地市场,完善了土地出让制度。但一些地方在招拍挂过程中,流标、流拍现象时有发生,既浪费了人力、财力,也一定程度上扰乱了土地市场的正常运行。     

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Nutrient and chlorophyll a anomaly in red-tide periods of 2003-2008 in Sishili Bay, China

Sishili Bay is the most important aquiculture and tourism area for the city of Yantai, China; however, red tides occurred frequently and have caused huge economic losses in this bay in recent years. To gain a better understanding of the local ecological environments in the bay, we conducted this research between 2003 and 2008 to analyze variations in nutrients and chlorophyll (chl-a) during high frequency red tide period (May to September). The results show that the chl-a concentration increased from 2.70 in 2003 to 7.26 mg/m3 in 2008, while the concentration of total inorganic nitrogen (TIN) and silicate (SiO3-Si) increased lineally from 5.18 and 1.45 μmol/L in 2003 to 18.57 and 9.52 μmol/L in 2008, respectively, and the annual phosphate (PO4-P) varied between 0.15 and 0.46 μmol/L. Special attention was given to a red tide in August 2007 occurred when water temperature was high and nutrient concentrations increased sharply because of a heavy rainfall. Overall, the results show the P limitation in Sishili Bay, and reveal that red tides were caused by eutrophication from terrestrial inputs and local warm weather, particularly during rainy periods. Therefore, to control red tide, greater efforts should be made to reduce sewage discharges into Sishili Bay, particularly during rainfall seasons.     

Hematological changes in white spot syndrome virus-infected shrimp, Fenneropenaeus chinensis (Osbeck)

The pathological changes of hemocytes in the haemolymph and hepatopancreas were examined in experimentally and naturally WSSV (white spot syndrome virus) infected Fenneropenaeus chinensis. The results showed that the pathological manifestations of hemocytes were similar among moribund shrimps infected via injection, feeding and by nature. Firstly, the total hemocyte counts (THCs) in WSSV-infected shrimp were significantly lower than those in healthy shrimp. Secondly, necrotic, broken and disintegrated cells were often observed, and a typical hematolysis was present in the haemolymph smear of WSSV-infected shrimp. Thirdly, necrosis and typical apoptosis of hemocytes were detected with TEM in the peripheral haemolymph of WSSV-infected shrimp. Hyalinocytes and semi-granulocytes with masses of WSSVs in their nuclei often appeared, whereas no granular hemocytes with WSSV were found in the hepatopancreas of moribund infected shrimps. All our results supported that hemocytes were the main target cells of WSSV, and hyalinocytes and semigranular hemocytes seemed to be more favorable for WSSV infection in F. chinensis.