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Chaos game representation(CGR)-walk model for DNA sequences 被引量:4
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作者 高洁 徐振源 《Chinese Physics B》 SCIE EI CAS CSCD 2009年第1期370-376,共7页
Chaos game representation (CGR) is an iterative mapping technique that processes sequences of units, such as nucleotides in a DNA sequence or amino acids in a protein, in order to determine the coordinates of their ... Chaos game representation (CGR) is an iterative mapping technique that processes sequences of units, such as nucleotides in a DNA sequence or amino acids in a protein, in order to determine the coordinates of their positions in a continuous space. This distribution of positions has two features: one is unique, and the other is source sequence that can be recovered from the coordinates so that the distance between positions may serve as a measure of similarity between the corresponding sequences. A CGR-walk model is proposed based on CGR coordinates for the DNA sequences. The CGR coordinates are converted into a time series, and a long-memory ARFIMA (p, d, q) model, where ARFIMA stands for autoregressive fractionally integrated moving average, is introduced into the DNA sequence analysis. This model is applied to simulating real CGR-walk sequence data of ten genomic sequences. Remarkably long-range correlations are uncovered in the data, and the results from these models are reasonably fitted with those from the ARFIMA (p, d, q) model. 展开更多
关键词 CGR-walk model DNA sequence LONG-MEMORY ARFIMA(p d q model
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Chaos game representation walk model for the protein sequences 被引量:3
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作者 高洁 蒋丽丽 徐振源 《Chinese Physics B》 SCIE EI CAS CSCD 2009年第10期4571-4579,共9页
A new chaos game representation of protein sequences based on the detailed hydrophobic-hydrophilic (HP) model has been proposed by Yu et al (Physica A 337(2004) 171). A CGR-walk model is proposed based on the ne... A new chaos game representation of protein sequences based on the detailed hydrophobic-hydrophilic (HP) model has been proposed by Yu et al (Physica A 337(2004) 171). A CGR-walk model is proposed based on the new CGR coordinates for the protein sequences from complete genomes in the present paper. The new CCR coordinates based on the detailed HP model are converted into a time series, and a long-memory ARFIMA(p, d, q) model is introduced into the protein sequence analysis. This model is applied to simulating real CCR-walk sequence data of twelve protein sequences. Remarkably long-range correlations are uncovered in the data and the results obtained from these models are reasonably consistent with those available from the ARFIMA(p, d, q) model. 展开更多
关键词 chaos game representation CGR-walk model protein sequence long-memory ARFIMA(p d q model autocorrelation function
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Modeling the contribution of abiotic exchange to CO_2 flux in alkaline soils of arid areas 被引量:3
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作者 WenFeng WANG Xi CHEN +1 位作者 GePing LUO LongHui LI 《Journal of Arid Land》 SCIE CSCD 2014年第1期27-36,共10页
Recent studies on alkaline soils of arid areas suggest a possible contribution of abiotic exchange to soil CO2 flux(Fc).However,both the overall contribution of abiotic CO2 exchange and its drivers remain unknown.He... Recent studies on alkaline soils of arid areas suggest a possible contribution of abiotic exchange to soil CO2 flux(Fc).However,both the overall contribution of abiotic CO2 exchange and its drivers remain unknown.Here we analyzed the environmental variables suggested as possible drivers by previous studies and constructed a function of these variables to model the contribution of abiotic exchange to Fc in alkaline soils of arid areas.An automated flux system was employed to measure Fc in the Manas River Basin of Xinjiang Uygur autonomous region,China.Soil pH,soil temperature at 0–5 cm(Ts),soil volumetric water content at 0–5 cm(θs)and air temperature at10 cm above the soil surface(Tas)were simultaneously analyzed.Results highlight reduced sensitivity of Fc to Ts and good prediction of Fc by the model Fc=R10Q10(Tas–10)/10+r7q7(pH–7)+λTas+μθs+e which represents Fc as a sum of biotic and abiotic components.This presents an approximate method to quantify the contribution of soil abiotic CO2 exchange to Fc in alkaline soils of arid areas. 展开更多
关键词 soil respiration temperature sensitivity q10 model soil abiotic CO2 exchange soil alkalinity
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Bayesian Estimation for the Order of INAR(q)Model 被引量:1
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作者 MIAO GUAN-HONG WANG DE-HUI 《Communications in Mathematical Research》 CSCD 2016年第4期325-331,共7页
In this paper, we consider the problem of determining the order ofINAR(Q) model on the basis of the Bayesian estimation theory. The Bayesian es-timator for the order is given with respect to a squared-error loss fu... In this paper, we consider the problem of determining the order ofINAR(Q) model on the basis of the Bayesian estimation theory. The Bayesian es-timator for the order is given with respect to a squared-error loss function. The consistency of the estimator is discussed. The results of a simulation study for the estimation method are presented. 展开更多
关键词 INAR(q model Bayesian estimation squared-error loss function con-sistency
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Investigation on regional attenuation of Vrancea (Romania) intermediate-depth earthquakes
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作者 Florin Pavel Radu Vacareanu 《Earthquake Engineering and Engineering Vibration》 SCIE EI CSCD 2018年第3期501-509,共9页
This paper aims at investigating possible regional attenuation patterns in the case of Vrancea(Romania) intermediate-depth earthquakes.Almost 500 pairs of horizontal components recorded during 13 intermediate-depth ... This paper aims at investigating possible regional attenuation patterns in the case of Vrancea(Romania) intermediate-depth earthquakes.Almost 500 pairs of horizontal components recorded during 13 intermediate-depth Vrancea earthquakes are employed in order to evaluate the regional attenuation patterns.The recordings are grouped according to the azimuth with regard to the Vrancea seismic source and subsequently,Q models are computed for each azimuthal zone assuming similar geometrical spreading.Moreover,the local soil amplification which was disregarded in a previous analysis performed for Vrancea intermediate-depth earthquakes is now clearly evaluated.The results show minor differences between the four regions situated in front of the Carpathian Mountains and considerable differences in attenuation of seismic waves between the forearc and backarc regions(with regard to the Carpathian Mountains).Consequently,an average Q model of the type Q(f) = 115×f^1.25 is obtained for the four forearc regions,while a separate Q model of the type Q(f) = 70×f^0.90 is computed for the backarc region.These results highlight the need to evaluate the seismic hazard of Romania by using ground motion models which take into account the different attenuation between the forearc/backarc regions. 展开更多
关键词 Fourier amplitude spectrum azimuth dependency source-to-site distance q model local soil conditions
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Estimation and Testing for the Parameters of AR(p)-ARCH(q) under Ordered Restriction
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作者 王德辉 宋立新 +1 位作者 史宁中 李荣华 《Northeastern Mathematical Journal》 CSCD 2004年第4期379-382,共4页
Suppose that the time series Xt satisfieswhere α0≥δ>0,αi≥0 for i=1,2,…,q;βi,i=1,…,p, are real numbers; p and q are the order of the model. The sequence {ξt};(0,1) and is independent of {hs,s≤t} for fixed ... Suppose that the time series Xt satisfieswhere α0≥δ>0,αi≥0 for i=1,2,…,q;βi,i=1,…,p, are real numbers; p and q are the order of the model. The sequence {ξt};(0,1) and is independent of {hs,s≤t} for fixed t. The above model is usually written as AR(p)-ARCH(q).We consider stationary series AR(p)-ARCH(q) model and assume the stationary field is θ0. We express this statement asH1:α1≥α2…≥αq,β1≥β2≥…≥βp and we consider an order restricted testing problem, which is to testH0:α1=α2=…=αq,β1=β2=…=βpagainst H1-H0. We derive the likelihood ratio (LR) test statistic and its asymptotic distri- 展开更多
关键词 AR(p)-ARCH(q) model ordered restriction maximum likelihood estimator asymptotic properties quadratic program
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Estimation and Testing for the Parameters of AR(p)-ARCH(q) under Ordered Restriction
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作者 王德辉 宋立新 史宁中 《Northeastern Mathematical Journal》 CSCD 2005年第4期475-491,共17页
In this paper, we study a stationary AR(p)-ARCH(q) model with parameter vectors α and β. We propose a method for computing the maximum likelihood estimator (MLE) of parameters under the nonnegative restriction... In this paper, we study a stationary AR(p)-ARCH(q) model with parameter vectors α and β. We propose a method for computing the maximum likelihood estimator (MLE) of parameters under the nonnegative restriction. A similar method is also proposed for the case that the parameters are restricted by a simple order: α1≥α2≥…≥αq and β1≥β2≥…≥βp. The strong consistency of the above two estimators is discussed. Furthermore, we consider the problem of testing homogeneity of parameters against the simple order restriction. We give the likelihood ratio (LR) test statistic for the testing problem and derive its asymptotic null distribution. 展开更多
关键词 AR(p)-ARCH(q model ordered restriction maximum likelihood estimator asymptotic properties quadratic program
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Analysis of Network Traffic with Extreme Value Theory
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作者 舒炎泰 汪广洪 +2 位作者 高德云 刘嘉焜 王旭 《Transactions of Tianjin University》 EI CAS 2003年第2期131-135,共5页
It is very im portant to analyze network traffic in the network control and management. In thi s paper, extreme value theory is first introduced and a model with threshold met hods is proposed to analyze the character... It is very im portant to analyze network traffic in the network control and management. In thi s paper, extreme value theory is first introduced and a model with threshold met hods is proposed to analyze the characteristics of network traffic. In this mode l, only some traffic data that is greater than threshold value is considered. Th en the proposed model with the trace is simulated by using S Plus software. The modeling results show the network traffic model constructed from the extreme va lue theory fits well with that of empirical distribution. Finally, the extreme v alue model with the FARIMA(p,d,q) modeling is compared. The anal ytical results illustrate that extreme value theory has a good application foreg round in the statistic analysis of network traffic. In addition, since only some traffic data which is greater than the threshold is processed, the computation overhead is reduced greatly. 展开更多
关键词 extreme value theory generalized Pare to distribution threshold value FARIMA(p d q) model
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The adjustment of γ-aminobutyric acid_A tonic subunits in Huntington's disease:from transcription to translation to synaptic levels into the neostriatum
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作者 Abraham Rosas-Arellano Argel Estrada-Mondragón +2 位作者 Carola A.Mantellero Carlos Tejeda-Guzmán Maite A.Castro 《Neural Regeneration Research》 SCIE CAS CSCD 2018年第4期584-590,共7页
γ-Aminobutyric acid(GABA),plays a key role in all stages of life,also is considered the main inhibitory neurotransmitter.GABA activates two kind of membrane receptors known as GABAA and GABAB,the first one is respo... γ-Aminobutyric acid(GABA),plays a key role in all stages of life,also is considered the main inhibitory neurotransmitter.GABA activates two kind of membrane receptors known as GABAA and GABAB,the first one is responsible to render tonic inhibition by pentameric receptors containing α4-6,β3,δ,or ρ1-3 subunits,they are located at perisynaptic and/or in extrasynaptic regions.The biophysical properties of GABAA tonic inhibition have been related with cellular protection against excitotoxic injury and cell death in presence of excessive excitation.On this basis,GABAA tonic inhibition has been proposed as a potential target for therapeutic intervention of Huntington's disease.Huntington's disease is a neurodegenerative disorder caused by a genetic mutation of the huntingtin protein.For experimental studies of Huntington's disease mouse models have been developed,such as R6/1,R6/2,Hdh Q92,Hdh Q150,as well as YAC128.In all of them,some key experimental reports are focused on neostriatum.The neostriatum is considered as the most important connection between cerebral cortex and basal ganglia structures,its cytology display two pathways called direct and indirect constituted by medium sized spiny neurons expressing dopamine D1 and D2 receptors respectively,they display strong expression of many types of GABAA receptors,including tonic subunits.The studies about of GABAA tonic subunits and Huntington's disease into the neostriatum are rising in recent years,suggesting interesting changes in their expression and localization which can be used as a strategy to delay the cellular damage caused by the imbalance between excitation and inhibition,a hallmark of Huntington's disease. 展开更多
关键词 GABAA extrasynaptic and perisynaptic y-aminobutyric acidA receptors STRIATUM R6/1 R6/2 Hdhq92 Hdhq111 Hdhq150 N171-82q and YAC128 HD transgenics mice models CHOREA mutanthuntingtin inhibitory neurotransmission D1 medium sized spiny neurons D2 medium sized spiny neurons
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Does a General Temperature-Dependent Q10 Model of Soil Respiration Exist at Biome and Global Scale? 被引量:37
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作者 Hua CHEN Han-Qin TIAN 《Journal of Integrative Plant Biology》 SCIE CAS CSCD 2005年第11期1288-1302,共15页
Soil respiration (SR) is commonly modeled by a Q10 (an indicator of temperature sensitivity) function in ecosystem models. Q10 is usually treated as a constant of 2 in these models, although Q10 value of SR often ... Soil respiration (SR) is commonly modeled by a Q10 (an indicator of temperature sensitivity) function in ecosystem models. Q10 is usually treated as a constant of 2 in these models, although Q10 value of SR often decreases with increasing temperatures. It remains unclear whether a general temperature- dependent Q10 model of SR exists at biome and global scale. In this paper, we have compiled the long-term Q10 data of 38 SR studies ranging from the Boreal, Temperate, to Tropical/Sublropical biome on four continents. Our analysis indicated that the general temperature-dependent biome Q10 models of SR existed, especially in the Boreal and Temperate biomes. A single-exponential model was better than a simple linear model in fitting the average Q10 values at the biome scale. Average soil temperature is a better predictor of Q10 value than average air temperature in these models, especially in the Boreal biome. Soil temperature alone could explain about 50% of the Q10 variations in both the Boreal and Temperate biome single-exponential Q10 model. Q10 value of SR decreased with increasing soil temperature but at quite different rates among the three biome Q10 models. The k values (Q10 decay rate constants) were 0.09, 0.07, and 0.02/℃ in the Boreal, Temperate, and Tropical/Subtropical biome, respectively, suggesting that Q10 value is the most sensitive to soil temperature change in the Boreal biome, the second in the Temperate biome, and the least sensitive in the Tropical/ Subtropical biome. This also indirectly confirms that acclimation of SR in many soil warming experiments probably occurs. The k value in the "global" single-exponential Q10 model which combined both the Boreal and Temperate biome data set was 0.08/℃. However, the global general temperature-dependent Q10 model developed using the data sets of the three biomes is not adequate for predicting Q10 values of SR globally. The existence of the general temperature-dependent Q10 models of SR in the Boreal and Temperate biome has important implications for modeling SR, especially in the Boreal biome. More detail model runs are needed to exactly evaluate the impact of using a fixed Q10 vs a temperature-dependent Q10 on SR estimate in ecosystem models (e.g., TEM, Biome-BGC, and PnET). 展开更多
关键词 air temperature biome q10 model global q10 model simple linear model single-exponentialmodel soil respiration (SR) soil temperature temperature sensitivity q10).
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Order shrinkage and selection for the INGARCH(p,q)model
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作者 Yuan Tian Dehui Wang Xinyang Wang 《International Journal of Biomathematics》 SCIE 2021年第5期295-309,共15页
The integer-valued generalized autoregressive conditional heteroskedastic(INGARCH)model is often utilized to describe data in biostatistics,such as the number of people infected with dengue fever,daily epileptic seizu... The integer-valued generalized autoregressive conditional heteroskedastic(INGARCH)model is often utilized to describe data in biostatistics,such as the number of people infected with dengue fever,daily epileptic seizure counts of an epileptic patient and the number of cases of campylobacterosis infections,etc.Since the structure of such data is generally high-order and sparse,studies about order shrinkage and selection for the model attract many attentions.In this paper,we propose a penalized conditional maximum likelihood(PCML)method to solve this problem.The PCML method can effectively select significant orders and estimate the parameters,simultaneously.Some simulations and a real data analysis are carried out to illustrate the usefulness of our method. 展开更多
关键词 INGARCH(p q)model penalized conditional maximum likelihood oracle properties EPIDEMIOLOGY
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