In this paper, an optimal adaptive H-infinity tracking control design method via wavelet network for a class of uncertain nonlinear systems with external disturbances is proposed to achieve H-infinity tracking perform...In this paper, an optimal adaptive H-infinity tracking control design method via wavelet network for a class of uncertain nonlinear systems with external disturbances is proposed to achieve H-infinity tracking performance. First, an alternate tracking error and a performance index with respect to the tracking error and the control effort are introduced in order to obtain better performance, especially, in reducing the cost of the control effort in the case of small attenuation levels. Next, H-infinity tracking performance, which attenuates the influence of both wavelet network approximation error and external disturbances on the modified tracking error, is formulated. Our results indicate that a small attenuation level does not lead to a large control signal. The proposed method insures an optimal trade-off between the amplitude of control signals and the performance of tracking errors. An example is given to illustrate the design efficiency.展开更多
Box C/D RNAs guide the site-specific formation of 2′-O-methylated nucleotides(Nm)of RNAs in eukaryotes and archaea.Although C/D RNAs have been profiled in several archaea,their targets have not been experimentally de...Box C/D RNAs guide the site-specific formation of 2′-O-methylated nucleotides(Nm)of RNAs in eukaryotes and archaea.Although C/D RNAs have been profiled in several archaea,their targets have not been experimentally determined.Here,we mapped Nm in r RNAs,t RNAs,and abundant small RNAs(s RNAs)and profiled C/D RNAs in the crenarchaeon Sulfolobus islandicus.The targets of C/D RNAs were assigned by analysis of base-pairing interactions,in vitro modification assays,and gene deletion experiments,revealing a complicated landscape of C/D RNA-target interactions.C/D RNAs widely use dual antisense elements to target adjacent sites in r RNAs,enhancing modification at weakly bound sites.Two consecutive sites can be guided with the same antisense element upstream of box D or D′,a phenomenon known as doublespecificity that is exclusive to internal box D′in eukaryotic C/D RNAs.Several C/D RNAs guide modification at a single non-canonical site.This study reveals the global landscape of RNA-guided 2′-O-methylation in an archaeon and unexpected targeting rules employed by C/D RNA.展开更多
Polyamines have been discovered for hundreds of years and once considered as a class of phytohormones.Polyamines play critical roles in a range of developmental processes.However,the molecular mechanisms of polyamine ...Polyamines have been discovered for hundreds of years and once considered as a class of phytohormones.Polyamines play critical roles in a range of developmental processes.However,the molecular mechanisms of polyamine signaling pathways remain poorly understood.Here,we measured the contents of main types of polyamines,and found that endogenous level of thermospermine(T-Spm)in Arabidopsis thaliana is comparable to those of classic phytohormones and is significantly lower than those of putrescine(Put),spermidine(Spd),and spermine(Spm).We further found a nodule-like structure around the junction area connecting the shoot and root of the T-Spm biosynthetic mutant acl5 and obtained more than 50 suppressors of acl5 nodule structure(san)through suppressor screening.An in-depth study of two san suppressors revealed that NAP57 and NOP56,core components of box H/ACA and C/D snoRNPs,were essential for T-Spm-mediated nodule-like structure formation and plant height.Furthermore,analyses of rRNA modifications showed that the overall levels of pseudouridylation and 2′-O-methylation were compromised in san1 and san2 respectively.Taken together,these results establish a strong genetic relationship between rRNA modification and T-Spm-mediated growth and development,which was previously undiscovered in all organisms.展开更多
Genotyping of structural variations considering copy number variations(CNVs)is an infancy and challenging problem.CNVs,a prevalent form of critical genetic variations that cause abnormal copy numbers of large genomic ...Genotyping of structural variations considering copy number variations(CNVs)is an infancy and challenging problem.CNVs,a prevalent form of critical genetic variations that cause abnormal copy numbers of large genomic regions in cells,often affect transcription and contribute to a variety of diseases.The characteristics of CNVs often lead to the ambiguity and confusion of existing genotyping features and algorithms,which may cause heterozygous variations to be erroneously genotyped as homozygous variations and seriously affect the accuracy of downstream analysis.As the allelic copy number increases,the error rate of genotyping increases sharply.Some instances with different copy numbers play an auxiliary role in the genotyping classification problem,but some will seriously interfere with the accuracy of the model.Motivated by these,we propose a transfer learning-based method to genotype structural variations accurately considering CNVs.The method first divides the instances with different allelic copy numbers and trains the basic machine learning framework with different genotype datasets.It maximizes the weights of the instances that contribute to classification and minimizes the weights of the instances that hinder correct genotyping.By adjusting the weights of the instances with different allelic copy numbers,the contribution of all the instances to genotyping can be maximized,and the genotyping errors of heterozygote variations caused by CNVs can be minimized.We applied the proposed method to both the simulated and real datasets,and compared it to some popular algorithms including GATK,Facets and Gindel.The experimental results demonstrate that the proposed method outperforms the others in terms of accuracy,stability and efficiency.The source codes have been uploaded at github/TrinaZ/CNVtransfer for academic use only.展开更多
基金the National Natural Science Foundation of China (No.60774049)the Major State Basic Research Development Program of China (2002CB312200).
文摘In this paper, an optimal adaptive H-infinity tracking control design method via wavelet network for a class of uncertain nonlinear systems with external disturbances is proposed to achieve H-infinity tracking performance. First, an alternate tracking error and a performance index with respect to the tracking error and the control effort are introduced in order to obtain better performance, especially, in reducing the cost of the control effort in the case of small attenuation levels. Next, H-infinity tracking performance, which attenuates the influence of both wavelet network approximation error and external disturbances on the modified tracking error, is formulated. Our results indicate that a small attenuation level does not lead to a large control signal. The proposed method insures an optimal trade-off between the amplitude of control signals and the performance of tracking errors. An example is given to illustrate the design efficiency.
基金supported by the Strategic Priority Research Program of Chinese Academy of Sciences(XDB0570000,XDB37010201)the Basic Research Program Based on Major Scientific Infrastructures of Chinese Academy of Sciences(JZHKYPT-2021-05)+1 种基金the National Natural Science Foundation of China(91940302,91540201,31430024,31325007)the National Key Research and Development Program of China(2017YFA0504600)。
文摘Box C/D RNAs guide the site-specific formation of 2′-O-methylated nucleotides(Nm)of RNAs in eukaryotes and archaea.Although C/D RNAs have been profiled in several archaea,their targets have not been experimentally determined.Here,we mapped Nm in r RNAs,t RNAs,and abundant small RNAs(s RNAs)and profiled C/D RNAs in the crenarchaeon Sulfolobus islandicus.The targets of C/D RNAs were assigned by analysis of base-pairing interactions,in vitro modification assays,and gene deletion experiments,revealing a complicated landscape of C/D RNA-target interactions.C/D RNAs widely use dual antisense elements to target adjacent sites in r RNAs,enhancing modification at weakly bound sites.Two consecutive sites can be guided with the same antisense element upstream of box D or D′,a phenomenon known as doublespecificity that is exclusive to internal box D′in eukaryotic C/D RNAs.Several C/D RNAs guide modification at a single non-canonical site.This study reveals the global landscape of RNA-guided 2′-O-methylation in an archaeon and unexpected targeting rules employed by C/D RNA.
基金supported by the National Natural Science Foundation of China(31788103,32122012,32100221,91940302,31430024)the Strategic Priority Research Program of Chinese Academy of Sciences(XDA24040202)+1 种基金the Chinese Academy of Sciences Youth Innovation Promotion Association(2019099)the CAS Key Technology Talent Program(2017)。
文摘Polyamines have been discovered for hundreds of years and once considered as a class of phytohormones.Polyamines play critical roles in a range of developmental processes.However,the molecular mechanisms of polyamine signaling pathways remain poorly understood.Here,we measured the contents of main types of polyamines,and found that endogenous level of thermospermine(T-Spm)in Arabidopsis thaliana is comparable to those of classic phytohormones and is significantly lower than those of putrescine(Put),spermidine(Spd),and spermine(Spm).We further found a nodule-like structure around the junction area connecting the shoot and root of the T-Spm biosynthetic mutant acl5 and obtained more than 50 suppressors of acl5 nodule structure(san)through suppressor screening.An in-depth study of two san suppressors revealed that NAP57 and NOP56,core components of box H/ACA and C/D snoRNPs,were essential for T-Spm-mediated nodule-like structure formation and plant height.Furthermore,analyses of rRNA modifications showed that the overall levels of pseudouridylation and 2′-O-methylation were compromised in san1 and san2 respectively.Taken together,these results establish a strong genetic relationship between rRNA modification and T-Spm-mediated growth and development,which was previously undiscovered in all organisms.
基金supported by the National Natural Science Foundation of China under Grant Nos.61074044, 61104038,and 60834004Specialized Research Fund for the Doctoral Program of Higher Education of China under Grant No.20090041110003the National 973 Basic Research Program of China under Grant Nos. 2009CB320602 and 2002CB312200
基金supported by the National Natural Science Foundation of China (Grant No.31701150)the Fundamental Research Funds for the Central Universities (CXTD2017003).
文摘Genotyping of structural variations considering copy number variations(CNVs)is an infancy and challenging problem.CNVs,a prevalent form of critical genetic variations that cause abnormal copy numbers of large genomic regions in cells,often affect transcription and contribute to a variety of diseases.The characteristics of CNVs often lead to the ambiguity and confusion of existing genotyping features and algorithms,which may cause heterozygous variations to be erroneously genotyped as homozygous variations and seriously affect the accuracy of downstream analysis.As the allelic copy number increases,the error rate of genotyping increases sharply.Some instances with different copy numbers play an auxiliary role in the genotyping classification problem,but some will seriously interfere with the accuracy of the model.Motivated by these,we propose a transfer learning-based method to genotype structural variations accurately considering CNVs.The method first divides the instances with different allelic copy numbers and trains the basic machine learning framework with different genotype datasets.It maximizes the weights of the instances that contribute to classification and minimizes the weights of the instances that hinder correct genotyping.By adjusting the weights of the instances with different allelic copy numbers,the contribution of all the instances to genotyping can be maximized,and the genotyping errors of heterozygote variations caused by CNVs can be minimized.We applied the proposed method to both the simulated and real datasets,and compared it to some popular algorithms including GATK,Facets and Gindel.The experimental results demonstrate that the proposed method outperforms the others in terms of accuracy,stability and efficiency.The source codes have been uploaded at github/TrinaZ/CNVtransfer for academic use only.