Introduction The study on earthquake nucleation is widely concerned by seismologists in the world. The experimental and theoretical studies indicate that earthquakes should be preceded by quasi-static slip wit... Introduction The study on earthquake nucleation is widely concerned by seismologists in the world. The experimental and theoretical studies indicate that earthquakes should be preceded by quasi-static slip within a nucleation zone (Oh-naka, 1992; Dodge, Beroza, 1995; Dodge, et al, 1996; Ohnaka, Kuwahara, 1990; Yamashita, Ohnaka, 1991). The earthquake nucleation process means a transition from quasi-static to quasi-dynamic rupture process, and it itself is a short-term precursor. Immediate foreshocks are local dynamic instabilities that occur during the transition from the quasi-static to the quasi-dynamic nucleation of the dynamic instability (Ohnaka, 1992). According to the recent theoretical study, immediate foreshocks can be regarded as the localized fractures accompanied by the quasi-static nucleation process of a large earthquake (Shibazaki, Matsu'ura, 1995). Therefore, foreshocks could occur during the nucleation process. The nucleation of earthquakes can be illuminated through analyzing foreshock activity in detail. Detection of the nucleation process by means of a foreshock study is a potential tool for earthquake predic-tion. The nucleation process of Izu peninsula earthquake with M=7.0 on January 14, 1978 is revealed by Ohnaka with foreshock activities. It was observed that the nucleation zone indicated by foreshocks grew at a rate of 1～40 cm/s before reaching a diameter of 10 km. The depths of foreshocks do not change much more, keep within 10 km. Recently, Hurukawa have studied the nucleation process of Off-Etorofu earthquake with MW=7.9 on December 3, 1995. The results show distinctly the nucleation process before the main shock. In the nucleation process, rupture started at the deepest point of the foreshock area, and then propagated to the shallow depth with the apparent ve-locity of 5～20 cm/s (Hurukawa, 1998). Rastogi and Mandal (1998) studied the rupture nucleation process of five Koyna medium-sized main shocks using the time-space patterns of foreshocks. They found that the nucleation zone grew at a rate of 0.5～10 cm/s until it finally attained a diameter of about 10 km before the occurrence of the main shock and the fracture nucleated at shallow depths and gradually deepened, the main shock occurred at the deepest point of the nucleation zone, that is, at the depth of about 8～11 km. Foreshock distribution showed a good agreement with the preslip model of earthquake nucleation (Rastogi, Mandal, 1998).……展开更多
The germplasm resources for the S-type male sterility is rich in maize and it is resistant to Bipolaris maydis race T and CI, but the commercial application of S-type cytoplasmic male sterility(CMS-S) in maize hybrid ...The germplasm resources for the S-type male sterility is rich in maize and it is resistant to Bipolaris maydis race T and CI, but the commercial application of S-type cytoplasmic male sterility(CMS-S) in maize hybrid industry is greatly compromised because of its common fertility instability. Currently, the existence of multiple minor effect loci in specific nuclear genetic backgrounds was considered as the molecular mechanism for this phenomenon. In the present study, we evaluated the fertility segregation of the different populations with the fertility instable material FIL-H in two environments of Beijing and Hainan, China. Our results indicated that the fertility instability of FIL-H was regulated by multiple genes, and the expression of these genes was sensitive to environmental factors. Using RNA sequencing(RNA-seq) technology, transcriptomes of the sterile plants and partially fertile plants resulted from the backcross of FIL-H×Jing 724 in Hainan were analyzed and 2 108 genes with different expression were identified, including 1 951 up-regulated and 157 down-regulated genes. The cluster analysis indicated that these differentially expressed genes(DEGs) might play roles in many biological processes, such as the energy production and conversion, carbohydrate metabolism and signal transduction. In addition, the pathway of the starch and sucrose metabolism was emphatically investigated to reveal the DEGs during the process of starch biosynthesis between sterile and partially fertile plants, which were related to the key catalytic enzymes, such as ADP-G pyrophosphorylase, starch synthase and starch branching enzyme. The up-regulation of these genes in the partially fertile plant may promote the starch accumulation in its pollen. Our data provide the important theoretical basis for the further exploration of the molecular mechanism for the fertility instability in CMS-S maize.展开更多
MicroRNAs (miRNAs) are endogenous small RNAs that play important regulatory roles in the growth and development processes of plants and animals. In this study, we examined the expression profiles of pollen miRNAs from...MicroRNAs (miRNAs) are endogenous small RNAs that play important regulatory roles in the growth and development processes of plants and animals. In this study, we examined the expression profiles of pollen miRNAs from a maize S type cytoplasmic male sterile line and its fertility restored line. In total, 100 known miRNAs belonging to 20 families and 81 novel miRNAs belonging to 44 families were identified. Two and seven known miRNAs had significant expression difference between the two lines at the level of P-value<0.01 and 0.01<P-value<0.05, respectively. Four miRNAs showing >1.5 fold expression difference were verified by stem-loop RT-qPCR. Gene Ontology analysis of miRNA target genes revealed that these genes mainly participated in the transcriptional regulation processes.展开更多
文摘为提高高速公路改扩建工程交通安全风险评估结果的确定性和准确性,建立了基于改进D-S证据理论的相关风险评估模型。首先建立包含24个影响因素的三层级评估指标体系;然后利用云模型(Cloud Model,CM)求出定性指标的基本信度赋值(Basic Probability Assignment,BPA),利用高斯隶属度函数求出定量指标BPA;接着,通过层次分析法确定各评估指标的权重,进而对各指标BPA进行加权;利用D-S证据理论融合加权后的BPA,归一化处理后得到改扩建工程交通安全风险状态评估结果。最后,为验证模型的准确性,选取沪陕高速公路平潮至广陵段高速公路改扩建工程作为实例进行交通安全风险评估。评估结果显示,实例工程的低风险水平隶属度最大,为0.6615,表明该实例总体处于低风险水平,与现有资料和现实情况吻合。同时发现,基于CM、AHP及D-S证据理论的评估模型对各评估指标进行量化、加权、融合后所得到的风险等级隶属度和不确定性有所区别,能更均衡地表示风险的隶属度,量化后的安全风险状态评估结果具有更好的准确性,解决了指标体系中模糊定性指标难以量化表征及指标差异化权重赋值的难题。
基金国家重点基础研究发展计划(973计划)，Mechanism and Prediction for StrongContinental Earthquakes from China Seismological Bureau
文摘 Introduction The study on earthquake nucleation is widely concerned by seismologists in the world. The experimental and theoretical studies indicate that earthquakes should be preceded by quasi-static slip within a nucleation zone (Oh-naka, 1992; Dodge, Beroza, 1995; Dodge, et al, 1996; Ohnaka, Kuwahara, 1990; Yamashita, Ohnaka, 1991). The earthquake nucleation process means a transition from quasi-static to quasi-dynamic rupture process, and it itself is a short-term precursor. Immediate foreshocks are local dynamic instabilities that occur during the transition from the quasi-static to the quasi-dynamic nucleation of the dynamic instability (Ohnaka, 1992). According to the recent theoretical study, immediate foreshocks can be regarded as the localized fractures accompanied by the quasi-static nucleation process of a large earthquake (Shibazaki, Matsu'ura, 1995). Therefore, foreshocks could occur during the nucleation process. The nucleation of earthquakes can be illuminated through analyzing foreshock activity in detail. Detection of the nucleation process by means of a foreshock study is a potential tool for earthquake predic-tion. The nucleation process of Izu peninsula earthquake with M=7.0 on January 14, 1978 is revealed by Ohnaka with foreshock activities. It was observed that the nucleation zone indicated by foreshocks grew at a rate of 1～40 cm/s before reaching a diameter of 10 km. The depths of foreshocks do not change much more, keep within 10 km. Recently, Hurukawa have studied the nucleation process of Off-Etorofu earthquake with MW=7.9 on December 3, 1995. The results show distinctly the nucleation process before the main shock. In the nucleation process, rupture started at the deepest point of the foreshock area, and then propagated to the shallow depth with the apparent ve-locity of 5～20 cm/s (Hurukawa, 1998). Rastogi and Mandal (1998) studied the rupture nucleation process of five Koyna medium-sized main shocks using the time-space patterns of foreshocks. They found that the nucleation zone grew at a rate of 0.5～10 cm/s until it finally attained a diameter of about 10 km before the occurrence of the main shock and the fracture nucleated at shallow depths and gradually deepened, the main shock occurred at the deepest point of the nucleation zone, that is, at the depth of about 8～11 km. Foreshock distribution showed a good agreement with the preslip model of earthquake nucleation (Rastogi, Mandal, 1998).……
基金supported by the National Key Technologies R&D Program of China during the 12th Five-year Plan period(2014BAD01B09)the Beijing Postdoctoral Research Foundation,China(2014ZZ-68)+2 种基金the Sci-Technology Innovation Project of Beijing Academy of Agriculture and Forestry Science(BAAFS),China(KJCX20140202)the Innovative Team Construction Project of BAAFS,China(JNKYT201603)the Postdoctoral Scientific Fund of BAAFS,China(2014013)
文摘The germplasm resources for the S-type male sterility is rich in maize and it is resistant to Bipolaris maydis race T and CI, but the commercial application of S-type cytoplasmic male sterility(CMS-S) in maize hybrid industry is greatly compromised because of its common fertility instability. Currently, the existence of multiple minor effect loci in specific nuclear genetic backgrounds was considered as the molecular mechanism for this phenomenon. In the present study, we evaluated the fertility segregation of the different populations with the fertility instable material FIL-H in two environments of Beijing and Hainan, China. Our results indicated that the fertility instability of FIL-H was regulated by multiple genes, and the expression of these genes was sensitive to environmental factors. Using RNA sequencing(RNA-seq) technology, transcriptomes of the sterile plants and partially fertile plants resulted from the backcross of FIL-H×Jing 724 in Hainan were analyzed and 2 108 genes with different expression were identified, including 1 951 up-regulated and 157 down-regulated genes. The cluster analysis indicated that these differentially expressed genes(DEGs) might play roles in many biological processes, such as the energy production and conversion, carbohydrate metabolism and signal transduction. In addition, the pathway of the starch and sucrose metabolism was emphatically investigated to reveal the DEGs during the process of starch biosynthesis between sterile and partially fertile plants, which were related to the key catalytic enzymes, such as ADP-G pyrophosphorylase, starch synthase and starch branching enzyme. The up-regulation of these genes in the partially fertile plant may promote the starch accumulation in its pollen. Our data provide the important theoretical basis for the further exploration of the molecular mechanism for the fertility instability in CMS-S maize.
基金financially supported by the National Natural Science Foundation of China(31171565)
文摘MicroRNAs (miRNAs) are endogenous small RNAs that play important regulatory roles in the growth and development processes of plants and animals. In this study, we examined the expression profiles of pollen miRNAs from a maize S type cytoplasmic male sterile line and its fertility restored line. In total, 100 known miRNAs belonging to 20 families and 81 novel miRNAs belonging to 44 families were identified. Two and seven known miRNAs had significant expression difference between the two lines at the level of P-value<0.01 and 0.01<P-value<0.05, respectively. Four miRNAs showing >1.5 fold expression difference were verified by stem-loop RT-qPCR. Gene Ontology analysis of miRNA target genes revealed that these genes mainly participated in the transcriptional regulation processes.
