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Search Results: 1 - 10 of 28299 matches for " MA Jianzhong "
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Sequence analysis of a pseudogeue member in the 10kDa sulfur-rich prolamin gene family or the Chinese rice
水稻10kDa富硫醇溶蛋白基因家族中一个假基因拷贝的核苷酸序列分析

Ma Jianzhong,
马建忠

生物多样性 , 1995,
Abstract: In this paper, the 10kDa sulfur-rich prolamin gene was amplified by PCR, cloned and sequenced from Chinese rice. The sequence analysis showed that the amplified fragment was 380hp long, 94. 5% homologous to the nucleic acid sequence reported by Masumura et al. 1] and 99. 5% homologous to our previous re sultsl2]. The single base insertion between position 150 and 151 caused the reading frame mutation of the fragment and formed an amber codon at position between 162 to 164. These results showed that there would be a pseudogene member in the 10kDa sulfur-rich prolamin gene family.
Investigation of Inversion Polymorphisms in the Human Genome Using Principal Components Analysis
Jianzhong Ma, Christopher I. Amos
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0040224
Abstract: Despite the significant advances made over the last few years in mapping inversions with the advent of paired-end sequencing approaches, our understanding of the prevalence and spectrum of inversions in the human genome has lagged behind other types of structural variants, mainly due to the lack of a cost-efficient method applicable to large-scale samples. We propose a novel method based on principal components analysis (PCA) to characterize inversion polymorphisms using high-density SNP genotype data. Our method applies to non-recurrent inversions for which recombination between the inverted and non-inverted segments in inversion heterozygotes is suppressed due to the loss of unbalanced gametes. Inside such an inversion region, an effect similar to population substructure is thus created: two distinct “populations” of inversion homozygotes of different orientations and their 1:1 admixture, namely the inversion heterozygotes. This kind of substructure can be readily detected by performing PCA locally in the inversion regions. Using simulations, we demonstrated that the proposed method can be used to detect and genotype inversion polymorphisms using unphased genotype data. We applied our method to the phase III HapMap data and inferred the inversion genotypes of known inversion polymorphisms at 8p23.1 and 17q21.31. These inversion genotypes were validated by comparing with literature results and by checking Mendelian consistency using the family data whenever available. Based on the PCA-approach, we also performed a preliminary genome-wide scan for inversions using the HapMap data, which resulted in 2040 candidate inversions, 169 of which overlapped with previously reported inversions. Our method can be readily applied to the abundant SNP data, and is expected to play an important role in developing human genome maps of inversions and exploring associations between inversions and susceptibility of diseases.
Principal Components Analysis of Population Admixture
Jianzhong Ma, Christopher I. Amos
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0040115
Abstract: With the availability of high-density genotype information, principal components analysis (PCA) is now routinely used to detect and quantify the genetic structure of populations in both population genetics and genetic epidemiology. An important issue is how to make appropriate and correct inferences about population relationships from the results of PCA, especially when admixed individuals are included in the analysis. We extend our recently developed theoretical formulation of PCA to allow for admixed populations. Because the sampled individuals are treated as features, our generalized formulation of PCA directly relates the pattern of the scatter plot of the top eigenvectors to the admixture proportions and parameters reflecting the population relationships, and thus can provide valuable guidance on how to properly interpret the results of PCA in practice. Using our formulation, we theoretically justify the diagnostic of two-way admixture. More importantly, our theoretical investigations based on the proposed formulation yield a diagnostic of multi-way admixture. For instance, we found that admixed individuals with three parental populations are distributed inside the triangle formed by their parental populations and divide the triangle into three smaller triangles whose areas have the same proportions in the big triangle as the corresponding admixture proportions. We tested and illustrated these findings using simulated data and data from HapMap III and the Human Genome Diversity Project.
Theoretical Formulation of Principal Components Analysis to Detect and Correct for Population Stratification
Jianzhong Ma,Christopher I. Amos
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0012510
Abstract: The Eigenstrat method, based on principal components analysis (PCA), is commonly used both to quantify population relationships in population genetics and to correct for population stratification in genome-wide association studies. However, it can be difficult to make appropriate inference about population relationships from the principal component (PC) scatter plot. Here, to better understand the working mechanism of the Eigenstrat method, we consider its theoretical or “population” formulation. The eigen-equation for samples from an arbitrary number () of populations is reduced to that of a matrix of dimension , the elements of which are determined by the variance-covariance matrix for the random vector of the allele frequencies. Solving the reduced eigen-equation is numerically trivial and yields eigenvectors that are the axes of variation required for differentiating the populations. Using the reduced eigen-equation, we investigate the within-population fluctuations around the axes of variation on the PC scatter plot for simulated datasets. Specifically, we show that there exists an asymptotically stable pattern of the PC plot for large sample size. Our results provide theoretical guidance for interpreting the pattern of PC plot in terms of population relationships. For applications in genetic association tests, we demonstrate that, as a method of correcting for population stratification, regressing out the theoretical PCs corresponding to the axes of variation is equivalent to simply removing the population mean of allele counts and works as well as or better than the Eigenstrat method.
A Unified Framework Integrating Parent-of-Origin Effects for Association Study
Feifei Xiao, Jianzhong Ma, Christopher I. Amos
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0072208
Abstract: Genetic imprinting is the most well-known cause for parent-of-origin effect (POE) whereby a gene is differentially expressed depending on the parental origin of the same alleles. Genetic imprinting is related to several human disorders, including diabetes, breast cancer, alcoholism, and obesity. This phenomenon has been shown to be important for normal embryonic development in mammals. Traditional association approaches ignore this important genetic phenomenon. In this study, we generalize the natural and orthogonal interactions (NOIA) framework to allow for estimation of both main allelic effects and POEs. We develop a statistical (Stat-POE) model that has the orthogonal estimates of parameters including the POEs. We conducted simulation studies for both quantitative and qualitative traits to evaluate the performance of the statistical and functional models with different levels of POEs. Our results showed that the newly proposed Stat-POE model, which ensures orthogonality of variance components if Hardy-Weinberg Equilibrium (HWE) or equal minor and major allele frequencies is satisfied, had greater power for detecting the main allelic additive effect than a Func-POE model, which codes according to allelic substitutions, for both quantitative and qualitative traits. The power for detecting the POE was the same for the Stat-POE and Func-POE models under HWE for quantitative traits.
Prediction of Landscape Pattern of Soft Sandstone Area (SSA) after Seabuckthorn Planting  [PDF]
Jianzhong Hu
American Journal of Plant Sciences (AJPS) , 2012, DOI: 10.4236/ajps.2012.31020
Abstract: As a pioneer plant in the gully slopes in the Soft Sandstone Area (SSA) for eco-economical consideration, ten years (1999-2008) planting of seabuckthorn has made 1642.83 km2, or 9.84%, of the total area of SSA change into seabuckthorn coverage. In SSA the landscape has been divided into 9 types, such as seabuckthorn, sand, water, settlement, bush, open vegetation, forest, grassland and unused land. Seabuckthorn type is separated from the bush type for estimating the role of seabuckthron planting. By means of the Markov model, the developing trends of every landscape types can be determined to support the seabuckthorn project which influences the landscape pattern deeply in SSA. The prediction shows that the optimism ratio of seabuckthorn in the future should be 10.21%, the open vegetation 32.25%, and the forest percentage under 10%, which is a very wise tactics to avoid the serious death of various vegetations in SSA to match the local arid eco-environment.
Evaluation on Environmental Resource Value of Artificial Seabuckthorn Forest in Sandstone Area during 1999-2008  [PDF]
Jianzhong Hu
American Journal of Plant Sciences (AJPS) , 2013, DOI: 10.4236/ajps.2013.412286
Abstract:

China Seabuckthorn Ecological Project has been implemented for a decade (from 1999 to 2008) with an increasing seabuckthorn area of 1642.83 km2 in the Sandstone Areas of Shanxi, Shaanxi and Inner Mongoliathe most serious soil erosion area in China. The vast artificial seabuckthorn forest’s value in environmental resource is assessed via 7 indicators on first-level, 15 indicators on secondary level and 35 indicators on third level in this research. As of 2008, the seabuckthorn environmental resource value is 10.017 billion RMB Yuan, which equals to 37.1 times of the project’s total investment of 0.27 billion RMB Yuan. It is proposed in this research that the external economical values such as soil and water conservation, windbreak and sand-fixation can be realized through relative national policies and taxes. Carbon-fixation and oxygen-producing value can be achieved through the international carbon trade.

A Review of Atmospheric Chemistry Research in China: Photochemical Smog, Haze Pollution, and Gas-Aerosol Interactions

MA Jianzhong,XU Xiaobin,ZHAO Chunsheng,YAN Peng,

大气科学进展 , 2012,
Abstract: In this paper we present a review of atmospheric chemistry research in China over the period 2006--2010, focusing on tropospheric ozone, aerosol chemistry, and the interactions between trace gases and aerosols in the polluted areas of China. Over the past decade, China has suffered severe photochemical smog and haze pollution, especially in North China, the Yangtze River Delta, and the Pearl River Delta. Much scientific work on atmospheric chemistry and physics has been done to address this large-scale, complex environmental problem. Intensive field experiments, satellite data analyses, and model simulations have shown that air pollution is significantly changing the chemical and physical characters of the natural atmosphere over these parts of China. In addition to strong emissions of primary pollutants, photochemical and heterogeneous reactions play key roles in the formation of complex pollution. More in-depth research is recommended to reveal the formation mechanism of photochemical smog and haze pollution and their climatic effects at the urban, regional, and global scales.
Rheological properties of warm mix asphalt binderby DSR test at medium temperature
Zhang Jiupeng, Liu Guoqiang, Du Hui, Pei Jianzhong, Ma Xuejun
- , 2015, DOI: 10.3969/j.issn.1003-7985.2015.03.015
Abstract: The rheological properties including the complex modulus G* and the phase angle δ of matrix and warm mix asphalt(WMA)binders were measured by using the dynamic shear rheometer(DSR)test at the medium temperature ranging from 16 to 40 ℃, and the relationships between the fatigue factor G*sinδ and the matrix binder property, WMA additive and test temperature were established. It is found that G* decreases with the increasing temperature while δ increases inversely, and G* of the asphalt binder with high WMA additive dosage is large, and δ is small. G*sinδ exponentially decreases with the increasing temperature and linearly increases with the increase in additive dosage, and the amplitudes of variation are large at low temperatures and high additive dosages. The effect of WMA additive on the rheological property is more remarkable for the matrix asphalt binder with low G*. Besides, aging has a great effect on the property of matrix asphalt binder, and a slight effect on the interaction between asphalt and additive. The high additive dosage can increase the fatigue cracking potential of the asphalt binder.
GRAIN SHAPE EFFECT IN SUPERPLASTIC DEFORMATION
CUI Jianzhong MA Longxiang Northeast University of Technology,Shenyang,China,
CUI Jianzhong MA Longxiang Northeast University of Technology
,Shenyang,China

金属学报(英文版) , 1989,
Abstract: The method controlling grain shape in TMT processing and the effect of grain shape on char- acteristic parameters in superplastic deformation were discussed.The accommodation velocity of grahl boundary sliding,which is the dominant mechanism in superplastic deformation,and the contribution of each mechanism to the total strain,as influenced by grain shape,were ana- lyzed.Grain shape has been shown to be an essential structural factor for superplasticity.Then an analysis was made about the effect of grain shape on the region transition strain rate so that a new concept,critical aspect for superplasticity,was worked out.These predictions were compared with the measured results in an Al-Zn-Mg alloy.
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