Urban water supply network is a modern urban survival and development of the infrastructure of a city,and its normal running conditions have important significance. The actual hydraulic process in the variableload wat...Urban water supply network is a modern urban survival and development of the infrastructure of a city,and its normal running conditions have important significance. The actual hydraulic process in the variableload water distribution networks can be treated as the slow transient flow which belongs to the unsteady flow. This paper analyzes the multi-loops network slow transient model based on graph theory,and the link flow matrix is treated as the variables of the discrete solution model to simulate the process of the slow transient flow in the network. With the simulation of hydraulic regime in an actual pipe network,the changing laws of the flow in the pipes,nodal hydraulic heads and other hydraulic factors with the passage of time are obtained. Since the transient processes offer much more information than a steady process,the slow transient theory is not only practical on analyzing the hydraulic condition of the network,but also on identifying hydraulic resistance coefficients of pipes and detecting the leakage in networks.展开更多
A new method that is applicable to local seismic networks to estimate the azimuth and slowness of teleseismic signals is introduced in the paper. The method is based on the correlation between the arrival times and st...A new method that is applicable to local seismic networks to estimate the azimuth and slowness of teleseismic signals is introduced in the paper. The method is based on the correlation between the arrival times and station positions. The analyzed results indicate that the azimuth and slowness of teleseismic signals can be accurately estimated by the method. Average errors for azimuth and slowness measurements obtained by this method using data of Xi(an Digital Telemetry Seismic Network are 2.0o and 0.34 s/(o), respectively. The conclusions drawn from this study indicate that this method may be very useful to interpret teleseismic records of local seismic networks.展开更多
Neurons are believed to be the brain computational engines of the brain. A recent discovery in neurophysiology reveals that interneurons can slowly integrate spiking, share the output across a coupled network of axons...Neurons are believed to be the brain computational engines of the brain. A recent discovery in neurophysiology reveals that interneurons can slowly integrate spiking, share the output across a coupled network of axons and respond with persistent firing even in the absence of input to the soma or dendrites, which has not been understood and could be very important for exploring the mechanism of human cognition. The conventional models are incapable of simulating the important newly-discovered phenomenon of persistent firing induced by axonal slow integration. In this paper, we propose a computationally efficient model of neurons through modeling the axon as a slow leaky integrator, which captures almost all-known neural behaviors. The model controls the switching of axonal firing dynamics between passive conduction mode and persistent firing mode. The interplay between the axonal integrated potential and its multiple thresholds in axon precisely determines the persistent firing dynamics of neurons. We also present a persistent firing polychronous spiking network which exhibits asynchronous dynamics indicating that this computationally efficient model is not only bio-plausible, but also suitable for large scale spiking network simulations. The implications of this network and the analog circuit design for exploring the relationship between working memory and persistent firing enable developing a spiking network-based memory and bio-inspired computer systems.展开更多
Transmission control protocol (TCP) has undergone several transformations. Several proposals have been put forward to change the mechanisms of TCP congestion control to improve its performance. A line of research tend...Transmission control protocol (TCP) has undergone several transformations. Several proposals have been put forward to change the mechanisms of TCP congestion control to improve its performance. A line of research tends to reduce speed in the face of congestion thereby penalizing itself. In this group are the window based congestion control algorithms that use the size of congestion window to determine transmission speed. The two main algorithm of window based congestion control are the congestion avoidance and the slow start. The aim of this study is to survey the various modifications of window based congestion control. Much work has been done on congestion avoidance hence specific attention is placed on the slow start in order to motivate a new direction of research in network utility maximization. Mathematical modeling of the internet is discussed and proposals to improve TCP startup were reviewed. There are three lines of research on the improvement of slow start. A group uses the estimation of certain parameters to determine initial speed. The second group uses bandwidth estimation while the last group uses explicit request for network assistance to determine initial startup speed. The problems of each proposal are analyzed and a multiple startup for TCP is proposed. Multiple startups for TCP specify that startup speed is selectable from an n-arry set of algorithms. We then introduced the e-speed start which uses the prevailing network condition to determine a suitable starting speed.展开更多
Congestion control in wireless networks has been extensively investigated over the years and several schemes and techniques have been developed, all with the aim of improving performance in wireless net-work. With the...Congestion control in wireless networks has been extensively investigated over the years and several schemes and techniques have been developed, all with the aim of improving performance in wireless net-work. With the rapid expansion and implementation of wireless technology it is essential that the congestion control problem be solved. This paper presents a survey of five congestion control schemes which are dif-ferent in slow start threshold calculation, bandwidth estimation, and congestion window manipulation. A comprehensive comparison of these approaches is given in relation to assumptions, bandwidth estimation, congestion window size manipulation, performance evaluation, fairness and friendliness and improved throughput.展开更多
目的:通过生物信息技术探索济川煎的有效化学成分及其作用于人体的靶点基因,分析其治疗慢传输型便秘(slow transit constipation,STC)的机制。方法:通过中药系统药理学技术平台(traditional Chinese medicine systems pharmacology data...目的:通过生物信息技术探索济川煎的有效化学成分及其作用于人体的靶点基因,分析其治疗慢传输型便秘(slow transit constipation,STC)的机制。方法:通过中药系统药理学技术平台(traditional Chinese medicine systems pharmacology database and analysis platform,TCMSP)数据库检索和筛选济川煎的化学活性物质及其作用于人体的靶点蛋白,同时应用人类基因数据库(the human gene database,GeneCards)预测STC的作用靶点,构建活性成分-靶点网络图;通过String数据库平台构建蛋白-蛋白相互作用网络(protein-protein interactions,PPI),寻找PPI核心基因,再进行GO(gene ontology)富集分析和KEGG(kyoto encyclopedia of genes and genomes)富集分析,找出所涉及的信号通路,构建靶点-通路网络图。结果:济川煎治疗STC的关键化学成分共25个,与STC的共同靶点71个;GO富集包括金属离子应答、膜筏、磷酸酶结合等;KEGG富集包括卡波西氏肉瘤相关疱疹病毒感染、前列腺癌、乙型肝炎、大肠癌等;与上述通路匹配度较高的靶点基因包括丝裂原活化蛋白激酶3(mitogen-activated protein kinase 3,MAPK3)、丝裂原活化蛋白激酶1(mitogen-activated protein kinase 1,MAPK1)、RAC-α丝氨酸/苏氨酸蛋白激酶(RAC-alpha serine/threonine-protein kinase,Akt1)、BCL2-AssociatedX的蛋白质(BCL2-AssociatedX,BAX)、RAF原癌基因丝氨酸/苏氨酸-蛋白激酶(Raf-1 proto-oncogene,serine/threonine,RAF1)等。结论:济川煎可通过调节富集在卡波西氏肉瘤相关疱疹病毒感染、前列腺癌、乙型肝炎、大肠癌等通路的MAPK3、MAPK1、Akt1、BAX、RAF1等靶点对STC起治疗作用。展开更多
基金Sponsored by the National Natural Science Foundation of China(Grant No.50908064 and 51208158)the 46thChina Postdoctoral Science Foundation(Grant No.20090460912)
文摘Urban water supply network is a modern urban survival and development of the infrastructure of a city,and its normal running conditions have important significance. The actual hydraulic process in the variableload water distribution networks can be treated as the slow transient flow which belongs to the unsteady flow. This paper analyzes the multi-loops network slow transient model based on graph theory,and the link flow matrix is treated as the variables of the discrete solution model to simulate the process of the slow transient flow in the network. With the simulation of hydraulic regime in an actual pipe network,the changing laws of the flow in the pipes,nodal hydraulic heads and other hydraulic factors with the passage of time are obtained. Since the transient processes offer much more information than a steady process,the slow transient theory is not only practical on analyzing the hydraulic condition of the network,but also on identifying hydraulic resistance coefficients of pipes and detecting the leakage in networks.
基金Foundation of Verification Researches for Arm Control Technology
文摘A new method that is applicable to local seismic networks to estimate the azimuth and slowness of teleseismic signals is introduced in the paper. The method is based on the correlation between the arrival times and station positions. The analyzed results indicate that the azimuth and slowness of teleseismic signals can be accurately estimated by the method. Average errors for azimuth and slowness measurements obtained by this method using data of Xi(an Digital Telemetry Seismic Network are 2.0o and 0.34 s/(o), respectively. The conclusions drawn from this study indicate that this method may be very useful to interpret teleseismic records of local seismic networks.
文摘Neurons are believed to be the brain computational engines of the brain. A recent discovery in neurophysiology reveals that interneurons can slowly integrate spiking, share the output across a coupled network of axons and respond with persistent firing even in the absence of input to the soma or dendrites, which has not been understood and could be very important for exploring the mechanism of human cognition. The conventional models are incapable of simulating the important newly-discovered phenomenon of persistent firing induced by axonal slow integration. In this paper, we propose a computationally efficient model of neurons through modeling the axon as a slow leaky integrator, which captures almost all-known neural behaviors. The model controls the switching of axonal firing dynamics between passive conduction mode and persistent firing mode. The interplay between the axonal integrated potential and its multiple thresholds in axon precisely determines the persistent firing dynamics of neurons. We also present a persistent firing polychronous spiking network which exhibits asynchronous dynamics indicating that this computationally efficient model is not only bio-plausible, but also suitable for large scale spiking network simulations. The implications of this network and the analog circuit design for exploring the relationship between working memory and persistent firing enable developing a spiking network-based memory and bio-inspired computer systems.
文摘Transmission control protocol (TCP) has undergone several transformations. Several proposals have been put forward to change the mechanisms of TCP congestion control to improve its performance. A line of research tends to reduce speed in the face of congestion thereby penalizing itself. In this group are the window based congestion control algorithms that use the size of congestion window to determine transmission speed. The two main algorithm of window based congestion control are the congestion avoidance and the slow start. The aim of this study is to survey the various modifications of window based congestion control. Much work has been done on congestion avoidance hence specific attention is placed on the slow start in order to motivate a new direction of research in network utility maximization. Mathematical modeling of the internet is discussed and proposals to improve TCP startup were reviewed. There are three lines of research on the improvement of slow start. A group uses the estimation of certain parameters to determine initial speed. The second group uses bandwidth estimation while the last group uses explicit request for network assistance to determine initial startup speed. The problems of each proposal are analyzed and a multiple startup for TCP is proposed. Multiple startups for TCP specify that startup speed is selectable from an n-arry set of algorithms. We then introduced the e-speed start which uses the prevailing network condition to determine a suitable starting speed.
文摘Congestion control in wireless networks has been extensively investigated over the years and several schemes and techniques have been developed, all with the aim of improving performance in wireless net-work. With the rapid expansion and implementation of wireless technology it is essential that the congestion control problem be solved. This paper presents a survey of five congestion control schemes which are dif-ferent in slow start threshold calculation, bandwidth estimation, and congestion window manipulation. A comprehensive comparison of these approaches is given in relation to assumptions, bandwidth estimation, congestion window size manipulation, performance evaluation, fairness and friendliness and improved throughput.
文摘目的:通过生物信息技术探索济川煎的有效化学成分及其作用于人体的靶点基因,分析其治疗慢传输型便秘(slow transit constipation,STC)的机制。方法:通过中药系统药理学技术平台(traditional Chinese medicine systems pharmacology database and analysis platform,TCMSP)数据库检索和筛选济川煎的化学活性物质及其作用于人体的靶点蛋白,同时应用人类基因数据库(the human gene database,GeneCards)预测STC的作用靶点,构建活性成分-靶点网络图;通过String数据库平台构建蛋白-蛋白相互作用网络(protein-protein interactions,PPI),寻找PPI核心基因,再进行GO(gene ontology)富集分析和KEGG(kyoto encyclopedia of genes and genomes)富集分析,找出所涉及的信号通路,构建靶点-通路网络图。结果:济川煎治疗STC的关键化学成分共25个,与STC的共同靶点71个;GO富集包括金属离子应答、膜筏、磷酸酶结合等;KEGG富集包括卡波西氏肉瘤相关疱疹病毒感染、前列腺癌、乙型肝炎、大肠癌等;与上述通路匹配度较高的靶点基因包括丝裂原活化蛋白激酶3(mitogen-activated protein kinase 3,MAPK3)、丝裂原活化蛋白激酶1(mitogen-activated protein kinase 1,MAPK1)、RAC-α丝氨酸/苏氨酸蛋白激酶(RAC-alpha serine/threonine-protein kinase,Akt1)、BCL2-AssociatedX的蛋白质(BCL2-AssociatedX,BAX)、RAF原癌基因丝氨酸/苏氨酸-蛋白激酶(Raf-1 proto-oncogene,serine/threonine,RAF1)等。结论:济川煎可通过调节富集在卡波西氏肉瘤相关疱疹病毒感染、前列腺癌、乙型肝炎、大肠癌等通路的MAPK3、MAPK1、Akt1、BAX、RAF1等靶点对STC起治疗作用。
文摘利用网络药理学与代谢组学探讨枳实-厚朴药对治疗慢传输型便秘(slow transit constipation,STC)的潜在作用机制。使用中药系统药理数据库与分析平台筛选枳实与厚朴的化学成分及作用靶点,通过GeneCards、OMIM、DisGeNET数据库搜集STC的疾病预测靶点,运用维恩图获得成分与疾病的交集靶点,采用STRING数据库构建蛋白质-蛋白质相互作用网络,运用Cytoscape 3.8.0软件计算并筛选关键靶点,同时绘制中药-成分-靶点网络图,利用Metascape数据库对交集靶点进行GO(gene ontology)功能富集分析和KEGG(Kyoto encyclopedia of genes and genomes)通路富集分析。采用洛哌丁胺诱导法构建STC小鼠模型,给予枳实+厚朴灌胃给药后,对小鼠盲肠内容物进行基于气相色谱联合飞行时间质谱(GC/TOF-MS)的非靶向代谢组学检测,分析差异性代谢物。结果获得枳实-厚朴药对活性成分共24种,与STC疾病相关的交集靶点共106个,其中度值排名靠前的关键靶点包括AKT1、TNF、TP53、IL6、CASP3、JUN。GO分析发现可能涉及的生物学过程包括细胞对氮化合物的反应、细胞对脂质的反应、蛋白磷酸化的正调控、炎症反应的调节、离子传输的调节等。KEGG分析可能涉及的通路包括癌症通路、PI3K-AKT信号通路、钙信号通路、5-羟色胺能突触信号通路等。非靶向代谢组学检测共发现21种差异性代谢物,包括Akt相关性代谢物烟酸、果糖、原儿茶酸。本研究揭示枳实-厚朴药对通过多成分、多靶点、多通路对STC发挥治疗作用,其活性成分柚皮素和木犀草素,关键靶点Akt及相关性代谢物值得特别关注,这为后续基础研究提供了思路与理论依据。
