Grain-size class-Std(GSCStd) and Grain-size class-dD(GSCdD) methods are simple statistical approaches for classifying bulk grain-size distributions(GSDs) into grain-size fractions. Although these two methods were deve...Grain-size class-Std(GSCStd) and Grain-size class-dD(GSCdD) methods are simple statistical approaches for classifying bulk grain-size distributions(GSDs) into grain-size fractions. Although these two methods were developed based on similar statistical principles, the classification difference between these two methods has not been analyzed. In this study, GSCStd and GSCdD methods are conducted in thirteen grain-size data sequences to examine the applicability for identifying grain size fractions. Results show that, application of the GSCStd method is equivalent to that of the GSCdD method in identifying finer grain-size fractions, and the difference between the two methods mainly comes from the identification of coarse grain-size fractions. Thus, finer grain-size fractions are recommended for use in research of surface aeolian and paleo-aeolian sediments. In addition, our results do not completely agree with previous studies, coarser grain-size fractions in our case suggest that the GSCdD method may not be more applicable than the GSCStd method.展开更多
The loess accumulation process has great potential to record patterns of atmospheric circulation change,paleoclimate,and paleoenvironmental evolution.South-eastern Xizang is a climatically sensitive region and here,we...The loess accumulation process has great potential to record patterns of atmospheric circulation change,paleoclimate,and paleoenvironmental evolution.South-eastern Xizang is a climatically sensitive region and here,we analyze a loess profile at Ranwu in order to explore the processes and interactions of dust transport and paleoclimate evolution in the region.Based on parametric grain size end-member analysis,optically stimulated luminescence(OSL)dating,and environmental proxies we show that the Ranwu loess profile comprises five end members(EMs).EM1 represents the fine silt fraction transported by high-altitude westerly winds over long distances;EM2 represents the medium silt fraction accumulated by glacier winds;EM3 is the coarse silt fraction transported by local dust storms under the action of strong glacier winds;EM4 represents the very fine sand fraction transported by strong local dust storms,different wind strengths controls the relative proportion of EM3 and EM4 over time.EM5 is the coarse sand fraction formed from the product of strong weathering of gravels.OSL dating shows loess sedimentation at Ranwu started around 11.16 ka.The prevailing climate was generally warm and wet between 11.6 and 4.2 ka,with four cooling events at 10.50,9.18,7.85,and 6.37 ka.Extensive paleosol development between 8.2 and 4.2 ka,a change to dry and cold climate conditions was favorable for loess formation after 4.2 ka.The palaeoenvironmental changes and abrupt climate events recorded in the Ranwu loess sequence are consistent with Holocene global environmental changes.展开更多
mRNA differential display (DDRT-PCR) has been used to analyze different human fetal brain tissues of different developmental stages (13- and 33-week). According to the sequence of one EST obtained in this assay, a pai...mRNA differential display (DDRT-PCR) has been used to analyze different human fetal brain tissues of different developmental stages (13- and 33-week). According to the sequence of one EST obtained in this assay, a pair of primers have been designed to screen the arrayed human fetal brain cDNA library. A 1 .2-kb cDNA clone has been found. This cDNA con-展开更多
After screening human fetal brain cDNA library, a novel human cDNA encoding an RNA-binding protein was cloned and named GRY-RBP. Human GRY-RBP cDNA is 2 932 bp in length, and encodes a protein of 623 amino acids with ...After screening human fetal brain cDNA library, a novel human cDNA encoding an RNA-binding protein was cloned and named GRY-RBP. Human GRY-RBP cDNA is 2 932 bp in length, and encodes a protein of 623 amino acids with a deduced molecular mass of 69.6 ku. Human GRY-RBP contains three RNA recognition motifs (RRMs) and a glycine (G), tyrosin (Y)-rich C-terminus. Computer searches with sequence database revealed its moderate homology with RRMs of many RRM RNA-binding proteins. in this study, the full coding region and partial non-coding region of mouse GRY-RBP cDNA were amplified by PCR using mouse brain cDNA library as template. Three transcripts of Gry-rbp are expressed in ali tissues as shown by Northern blot, but the amounts in heart, planceta and skeletal muscle are considerably higher than those in other tissues.展开更多
In order to learn the mechanism of brain development and differentiation, 90 expressed sequence tags (ESTs) were isolated by differential display from the cerebrum and cerebellum of 13-week and 33-week fetal brains. A...In order to learn the mechanism of brain development and differentiation, 90 expressed sequence tags (ESTs) were isolated by differential display from the cerebrum and cerebellum of 13-week and 33-week fetal brains. After searching database, 74 of them represented novel genes, some of them were homologous to the brain development related genes. Using total cDNA probes, 79 of the ESTs and their expression differences in fetal brain were further characterized.展开更多
基金supported by project funding from Chongqing Normal University (No. 12XLB009)Key Projects in the National Science & Technology Program (No. 2006BAD26B0302)
文摘Grain-size class-Std(GSCStd) and Grain-size class-dD(GSCdD) methods are simple statistical approaches for classifying bulk grain-size distributions(GSDs) into grain-size fractions. Although these two methods were developed based on similar statistical principles, the classification difference between these two methods has not been analyzed. In this study, GSCStd and GSCdD methods are conducted in thirteen grain-size data sequences to examine the applicability for identifying grain size fractions. Results show that, application of the GSCStd method is equivalent to that of the GSCdD method in identifying finer grain-size fractions, and the difference between the two methods mainly comes from the identification of coarse grain-size fractions. Thus, finer grain-size fractions are recommended for use in research of surface aeolian and paleo-aeolian sediments. In addition, our results do not completely agree with previous studies, coarser grain-size fractions in our case suggest that the GSCdD method may not be more applicable than the GSCStd method.
基金supported by the National Natural Science Foundation of China(Grant No.41807448).
文摘The loess accumulation process has great potential to record patterns of atmospheric circulation change,paleoclimate,and paleoenvironmental evolution.South-eastern Xizang is a climatically sensitive region and here,we analyze a loess profile at Ranwu in order to explore the processes and interactions of dust transport and paleoclimate evolution in the region.Based on parametric grain size end-member analysis,optically stimulated luminescence(OSL)dating,and environmental proxies we show that the Ranwu loess profile comprises five end members(EMs).EM1 represents the fine silt fraction transported by high-altitude westerly winds over long distances;EM2 represents the medium silt fraction accumulated by glacier winds;EM3 is the coarse silt fraction transported by local dust storms under the action of strong glacier winds;EM4 represents the very fine sand fraction transported by strong local dust storms,different wind strengths controls the relative proportion of EM3 and EM4 over time.EM5 is the coarse sand fraction formed from the product of strong weathering of gravels.OSL dating shows loess sedimentation at Ranwu started around 11.16 ka.The prevailing climate was generally warm and wet between 11.6 and 4.2 ka,with four cooling events at 10.50,9.18,7.85,and 6.37 ka.Extensive paleosol development between 8.2 and 4.2 ka,a change to dry and cold climate conditions was favorable for loess formation after 4.2 ka.The palaeoenvironmental changes and abrupt climate events recorded in the Ranwu loess sequence are consistent with Holocene global environmental changes.
文摘mRNA differential display (DDRT-PCR) has been used to analyze different human fetal brain tissues of different developmental stages (13- and 33-week). According to the sequence of one EST obtained in this assay, a pair of primers have been designed to screen the arrayed human fetal brain cDNA library. A 1 .2-kb cDNA clone has been found. This cDNA con-
文摘After screening human fetal brain cDNA library, a novel human cDNA encoding an RNA-binding protein was cloned and named GRY-RBP. Human GRY-RBP cDNA is 2 932 bp in length, and encodes a protein of 623 amino acids with a deduced molecular mass of 69.6 ku. Human GRY-RBP contains three RNA recognition motifs (RRMs) and a glycine (G), tyrosin (Y)-rich C-terminus. Computer searches with sequence database revealed its moderate homology with RRMs of many RRM RNA-binding proteins. in this study, the full coding region and partial non-coding region of mouse GRY-RBP cDNA were amplified by PCR using mouse brain cDNA library as template. Three transcripts of Gry-rbp are expressed in ali tissues as shown by Northern blot, but the amounts in heart, planceta and skeletal muscle are considerably higher than those in other tissues.
文摘In order to learn the mechanism of brain development and differentiation, 90 expressed sequence tags (ESTs) were isolated by differential display from the cerebrum and cerebellum of 13-week and 33-week fetal brains. After searching database, 74 of them represented novel genes, some of them were homologous to the brain development related genes. Using total cDNA probes, 79 of the ESTs and their expression differences in fetal brain were further characterized.
