多源多角度遥感数据反演森林叶面积指数方法

利用北京1号和Landsat多源数据组合成4个角度多波段数据集, 在考虑森林三维垂直分布特点的基础上, 结合INFORM几何光学与辐射传输混合模型, 通过聚类+神经元网络方式, 建立相应的多源多角度LAI反演模型。最后利用实地LAI测量数据和MODIS LAI产品, 对不同角度组合和噪声水平下的LAI反演结果进行验证。结果表明: 在保证数据质量的条件下, 通过增加角度可以提高森林的LAI反演精度, 最终R²=0.713, RMSE=0.957, 比单个角度的反演精度平均提高约20%。     

基于复杂性度量的心率变异信号非线性分析

假设心率变异信号是累积－发放模型（Ｉｎｔｅｇｒａｔｅ－ｆｉｒｅ）与非线性动力学系统耦合产生的峰电位链（ＳｐｉｋｅＴｒａｉｎ）。以符号动力学为基础,提出利用峰电位间隔（ｉｎｔｅｒｓｐｉｋｅｉｎｔｅｒｖａｌ,ＩＳＩ）及其随机替代数据的Ｃ１、Ｃ２复杂度来定量刻划非线性动力学系统特性。结果表明：确定性驱动产生的峰电位间隔序列可以与随机性驱动产生的峰电位间隔序列区分开。因此,在噪声干扰较强的生理信号中,尤其是在不清楚非线性动力系统变量和峰电位间隔序列之间是否存在微分同胚的情况下,以复杂性度量来代替以Ｔａｋｅｎｓ嵌入定理为基础的关联维数、Ｌｙａｐｎｏｖ指数等描述动力系统特征的方法是合适的。最后通过２类共３７个个体,每个个体的心电数据为１０００个Ｒ－Ｒ间期的微分序列检验心率变异信号的非线性结构。     

基于13C标记的低磷胁迫杉木根系亲缘识别分析

为了探究低磷（P）胁迫下不同亲缘关系邻株对杉木生长的影响规律,验证杉木根系是否具有亲缘识别行为,采用室内盆栽控制试验,选择2个杉木半同胞家系（No.32、No.28）为试验材料,利用¹³C同位素标记方法,分别在不同供P水平条件下（1.0 mmol/L KH₂PO₄, P₁和0 mmol/L KH₂PO₄,P₀）,构建亲缘组(No.32+No.32^*,^*为进行¹³C同位素标记的植株)、非亲缘组（No.28+No.32^*）2种亲缘邻株栽植模式,以杉木单株栽植（No.32^*）为对照处理（CK）,分别对不同处理中No.32杉木幼苗的地上部进行¹³C同位素标记,测定不同亲缘邻株下的杉木根长、根表面积、根体积、根平均直径等生长指标,以及邻株参试苗木叶、茎、根的¹³C丰度的差异性。No.32^*的邻株植物在未标记¹³C的情况下检测出¹³C丰度发生显著变化。在不供P处理下发现非亲缘组No.28的全株总¹³C丰度显著高于亲缘组No.32,表明低P胁迫促进杉木与非亲缘邻株的C交流。不供P处理下非亲缘组No.32^*杉木全株生物量比亲缘组No.32^*低了31.3%,供P水平显著改变了杉木与邻株的相处生长模式,与非亲缘植株相邻的杉木全株生物量减少,根冠比降低,生长发育减弱。不供P处理下,非亲缘组No.32^*比CK组提高46.0%根表面积,降低74.7%根体积。不供P处理下,非亲缘邻株促进杉木根表面积增加,提高P获取能力,增强杉木地下部分竞争力。不供P处理下,非亲缘组No.32^*全株P含量与CK组没有显著差异,而亲缘组显著低于CK组,非亲缘组No.32^*全株P利用效率（PUE）显著低于亲缘组,可见,在低P胁迫下亲缘邻株可促进杉木PUE的提高,缓解杉木的低P胁迫,维持逆境中杉木的正常生长发育。本研究发现杉木与邻株存在基于¹³C交流的亲缘识别,低P胁迫下杉木面对亲缘植物表现出提高相互响应度,提高PUE,面对非亲缘植物则表现出较强竞争力。养分匮乏下,杉木面对不同的亲缘邻株做不同的应对策略,这为优化杉木人工林种内或种间混交经营管理提供了理论依据。     

No Observable Relationship Between the 12 Genes of Nervous System and Reasoning Skill in a Young Chinese Han Population

Reasoning skill is an advanced cognitive ability which is needed for drawing inferences from given information. It is well known that the ability depends on the neural network of the frontal and parietal brain regions. In this study, we hypothesized that some genes involved in neurotransmitter systems were related to reasoning skill. To confirm this hypothesis, we examined the effects of 13 genes (BDNF, NRSF, COMT, DBH, DRD ₂ , DRD ₃ , DAT ₁ , MAOA, GRM ₁, GRIN2B, TPH ₂ , 5-HT _2A , and 5-HT ₆ ) in neurotransmitter systems on the non-verbal reasoning and verbal reasoning skills. The results indicated there were on significant effects of the 17 functional variants of these genes on the performance of non-verbal reasoning and verbal analogical reasoning skills (χ² > 3.84, df = 1, P > 0.05). This study suggests that some of the functional variations in BDNF, COMT, DBH, DRD ₂ , DRD ₃ , MAOA, 5-HT _2A , 5-HT ₆ , GRM ₁ , and GRIN2B have no observable effects on the certain reasoning skills in a young healthy Chinese Han population.     

Ligation of the fibrin-binding domain by β-strand addition is sufficient for expansion of soluble fibronectin

How fibronectin (FN) converts from a compact plasma protein to a fibrillar component of extracellular matrix is not understood. "Functional upstream domain" (FUD), a polypeptide based on F1 adhesin of Streptococcus pyogenes, binds by anti-parallel β-strand addition to discontinuous sets of N-terminal FN type I modules, (2-5)FNI of the fibrin-binding domain and (8-9)FNI of the gelatin-binding domain. Such binding blocks assembly of FN. To learn whether ligation of (2-5)FNI, (8-9)FNI, or the two sets in combination is important for inhibition, we tested "high affinity downstream domain" (HADD), which binds by β-strand addition to the continuous set of FNI modules, (1-5)FNI, comprising the fibrin-binding domain. HADD and FUD were similarly active in blocking fibronectin assembly. Binding of HADD or FUD to soluble plasma FN exposed the epitope to monoclonal antibody mAbIII-10 in the tenth FN type III module ((10)FNIII) and caused expansion of FN as assessed by dynamic light scattering. Soluble N-terminal constructs truncated after (9)FNI or (3)FNIII competed better than soluble FN for binding of FUD or HADD to adsorbed FN, indicating that interactions involving type III modules more C-terminal than (3)FNIII limit β-strand addition to (1-5)FNI within intact soluble FN. Preincubation of FN with mAbIII-10 or heparin modestly increased binding to HADD or FUD. Thus, ligation of FNIII modules involved in binding of integrins and glycosaminoglycans, (10)FNIII and (12-14)FNIII, increases accessibility of (1-5)FNI. Allosteric loss of constraining interactions among (1-5)FNI, (10)FNIII, and (12-14)FNIII likely enables assembly of FN into extracellular fibrils.     

Cadmium Is More Toxic on Volume Bone Mineral Density than Tissue Bone Mineral Density

It has been showed that Cd induces low areal bone mineral density, but we do not know the effect of Cd on cubic bone density. This study was aimed to investigate the effects of Cd on volumetric bone mineral density (VBMD) and tissue bone mineral density (TBMD) in male rats. Twenty-four Sprague-Dawley male rats were randomly divided into four groups that were given cadmium chloride by subcutaneous injection at doses of 0, 0.1, 0.5, and 1.5?mg/kg body weight for 8?weeks, respectively. Then, microcomputed tomography scanning was performed on the proximal tibia, and region of interest was reconstructed using microview software. The VBMD, bone volume fraction of rats treated with 1.5?mg Cd/kg, were significantly decreased compared to control (p?相似文献   

An Imputation Approach for Oligonucleotide Microarrays

Oligonucleotide microarrays are commonly adopted for detecting and qualifying the abundance of molecules in biological samples. Analysis of microarray data starts with recording and interpreting hybridization signals from CEL images. However, many CEL images may be blemished by noises from various sources, observed as “bright spots”, “dark clouds”, and “shadowy circles”, etc. It is crucial that these image defects are correctly identified and properly processed. Existing approaches mainly focus on detecting defect areas and removing affected intensities. In this article, we propose to use a mixed effect model for imputing the affected intensities. The proposed imputation procedure is a single-array-based approach which does not require any biological replicate or between-array normalization. We further examine its performance by using Affymetrix high-density SNP arrays. The results show that this imputation procedure significantly reduces genotyping error rates. We also discuss the necessary adjustments for its potential extension to other oligonucleotide microarrays, such as gene expression profiling. The R source code for the implementation of approach is freely available upon request.