空间五杆机构的可动性分析

机构的第2类可动性。是机构分析与综合所要探讨的基本问题之一。本文对一般形式的空间RRRSR五杆机构的可动性进行分析。通过拆开运动副,分析运动轨迹,根据其雅可比矩阵奇异获得各位形分支的边界后,采用拓朴变换原理,讨论得出该机构的装配条件和连架杆的运动情况。为空间多杆机构的第2类可动性分析,提供了一条方便、实用的途径。     

Genomic best linear unbiased prediction method reflecting the degree of linkage disequilibrium

The degree of linkage disequilibrium (LD) between markers differs depending on the location of the genome; this difference biases genetic evaluation by genomic best linear unbiased prediction (GBLUP). To correct this bias, we used three GBLUP methods reflecting the degree of LD (GBLUP‐LD). In the three GBLUP‐LD methods, genomic relationship matrices were conducted from single nucleotide polymorphism markers weighted according to local LD levels. The predictive abilities of GBLUP‐LD were investigated by estimating variance components and assessing the accuracies of estimated breeding values using simulation data. When quantitative trait loci (QTL) were located at weak LD regions, the predictive abilities of the three GBLUP‐LD methods were superior to those of GBLUP and Bayesian lasso except when the number of QTL was small. In particular, the superiority of GBLUP‐LD increased with decreasing trait heritability. The rates of QTL at weak LD regions would increase when selection by GBLUP continues; this consequently decreases the predictive ability of GBLUP. Thus, the GBLUP‐LD could be applicable for populations selected by GBLUP for a long time. However, if QTL were located at strong LD regions, the accuracies of three GBLUP‐LD methods were lower than GBLUP and Bayesian lasso.     

Estimates of genetic variance and variance of predicted genetic merits using pedigree or genomic relationship matrices in six Brown Swiss cattle populations for different traits

The amount of variance captured in genetic estimations may depend on whether a pedigree‐based or genomic relationship matrix is used. The purpose of this study was to investigate the genetic variance as well as the variance of predicted genetic merits (PGM) using pedigree‐based or genomic relationship matrices in Brown Swiss cattle. We examined a range of traits in six populations amounting to 173 population‐trait combinations. A main aim was to determine how using different relationship matrices affect variance estimation. We calculated ratios between different types of estimates and analysed the impact of trait heritability and population size. The genetic variances estimated by REML using a genomic relationship matrix were always smaller than the variances that were similarly estimated using a pedigree‐based relationship matrix. The variances from the genomic relationship matrix became closer to estimates from a pedigree relationship matrix as heritability and population size increased. In contrast, variances of predicted genetic merits obtained using a genomic relationship matrix were mostly larger than variances of genetic merit predicted using pedigree‐based relationship matrix. The ratio of the genomic to pedigree‐based PGM variances decreased as heritability and population size rose. The increased variance among predicted genetic merits is important for animal breeding because this is one of the factors influencing genetic progress.     

Analysis of Regular Nutritional Components and Amino Acid Contents of Mongolia Bullock Muscle Grazed in Kubuqi Desert

In order to evaluate the Mongolia muscle characteristics and nutritional value, six Mongolia bullocks aged 4 years grazed in Kubuqi desert were chosen to analyze the regular nutritional components and amino acid contents of Mongolia muscle.The results showed that the contents of water, crude protein (CP), crude fat (EE), crude ash (ash), calcium and phosphorus of Mongolia muscle (fresh) were 68.21%, 22.60%, 6.49%, 2.69%, 0.58% and 0.55%, respectively.A total amino acid (TAA) content of beef was 24.297 g/100 g, essential amino acid content was 10.265 g/100 g, the proportion of essential amino acid justified and exceeded the FAO/WHO standard.The ratio of essential amino acid and total amino acid contents (EAA/TAA) was 42.25%, the ratio of essential amino acid and the non-essential amino acid (EAA/NEAA) was 73.15%.In functional amino acid, the content of palatable taste amino acid and sweet flavor amino acid in total amino acid was 46.891%.In addition to valine, essential amino acid contents of Mongolia muscle were superior to ideal protein of FAO/WHO standard, the percentage of valine reached 83.972% in ideal protein.These results indicated that Mongolia muscle belonged to the comprehensive nutrition and high quality protein food on the evaluation of the regular nutrient content and the amino acid content of beef.     

基于转移矩阵和信息熵的地类变化分析——以钟山风景区为例

基于南京市钟山风景区1987-2002年森林资源二类调查数据,采用转移矩阵和地统计方法综合分析其地类变化。结果表明：1987-2002年,钟山风景区针叶林和非林地减少,阔叶林和针阔混交林地增加;600m幅度下的钟山风景区地类信息熵值空间格局层次感较强,1987年钟山风景区地类景观按信息熵值可分为高值区和低值区2个区域,其中高值区域主要分布于明孝陵景区、中山陵景区的中部,低值区域主要集中在自然景观区和山岳景观区;2002年钟山风景区地类景观按信息熵值可分为3个较高值区域和1个较低值区域,高值区域分布于明孝陵景区、中山陵景区的中部以及自然景区北部,低值区域位于自然风景区南部;1987-2002年,研究区地类信息熵低值区域在减少,高值区域在增加,但总体呈上升的变化趋势,一定程度说明土地利用结构向多样性发展,均衡性越来越强。     

Dramatic Changes of Matrix Metalloproteinases-7 and Lysozyme in the Ulcerative Colitis of Mice Induced by Dextran Sulfate Sodium

Ulcerative colitis （UC） is a lifelong illness with profound emotional and social impacts, and could cause serious damage to large intestine, especially in colon. However, the pathogenesis of UC remained unclear. The present study attempts to find out the role of matrix metalloproteinases-7 （MMP-7） and lysozyme in the pathogenesis of UC through a mice model induced by dextran sulfate sodium （DSS）. The UC model was evaluated both by disease activity index （DAI） and the intestinal histopathology. The results show that there is a high correlation between the DAI score and the pathological changes of colon. Interleukin-6 （IL-6） serum levels and large intestinal fluids levels in UC mice are always higher than that of the control groups, which might be associated with the degree of the inflammation damage in the colon. The change tendency of the MMP-7 mRNA and protein expressions are both up-regulated firstly and then down-regulated from 1 to 5 d in the colon, but only the MMP-7 protein is up-regulated at 7 d again. The up-regulated MMP-7 levels in the early stage of UC may play a protective role through the activated defensins, while the down-regulated levels in the mid-later stage of UC may be connected with the severe lesions in the colon. However, the up-regulated MMP-7 levels in the later stage of UC in the colon may also contribute to the tissue repair or be served as a marker to CRC （colorectal cancer）. The distribution of lysozyme protein indicates that there may be Paneth-like cells in the colon. Both the changes of MMP-7 and lysozyme in the small intestine may play a protective role for the safe environment of the whole gut, especially to the colon of UC.     

Incorporating spatial autocorrelation into the general linear model with an application to the yellowfin tuna (Thunnus albacares) longline CPUE data

Catch-per-unit-effort (CPUE) data have often been used to obtain a relative index of the abundance of a fish stock by standardizing nominal CPUE using various statistical methods. The theory underlying most of these methods assumes the independence of the observed CPUEs. This assumption is invalid for a fish population because of their spatial autocorrelation. To overcome this problem, we incorporated spatial autocorrelation into the standard general linear model (GLM). We also incorporated into it a habitat-based model (HBM), to reflect, more effectively, the vertical distributions of tuna. As a case study, we fitted both the standard-GLM and spatial-GLM (with or without HBM) to the yellowfin tuna CPUE data of the Japanese longline fisheries in the Indian Ocean. Four distance models (Gaussian, exponential, linear and spherical) were examined for spatial autocorrelation. We found that the spatial-GLMs always produced the best goodness-of-fit to the data and gave more realistic estimates of the variances of the parameters, and that HBM-based GLMs always produced better goodness-of-fit to the data than those without. Of the four distance models, the Gaussian model performed the best. The point estimates of the relative indices of the abundance of yellowfin tuna differed slightly between standard and spatial GLMs, while their 95% confidence intervals from the spatial-GLMs were larger than those from the standard-GLM. Therefore, spatial-GLMs yield more robust estimates of the relative indices of the abundance of yellowfin tuna, especially when the nominal CPUEs are strongly spatially autocorrelated.