Accuracy of imputation of single nucleotide polymorphism marker genotypes from low‐density panels in Japanese Black cattle

Using target and reference fattened steer populations, the performance of genotype imputation using lower‐density marker panels in Japanese Black cattle was evaluated. Population imputation was performed using BEAGLE software. Genotype information for approximately 40 000 single nucleotide polymorphism (SNP) markers by Illumina BovineSNP50 BeadChip was available, and imputation accuracy was assessed based on the average concordance rates of the genotypes, varying equally spaced SNP densities, and the number of individuals in the reference population. Two additional statistics were also calculated as indicators of imputation performance. The concordance rates tended to be lower for SNPs with greater minor allele frequencies, or those located near the ends of the chromosomes. Longer autosomes yielded greater imputation accuracies than shorter ones. When SNPs were selected based on linkage disequilibrium information, relative imputation accuracy was slightly improved. When 3000 and 10 000 equally spaced SNPs were used, the imputation accuracies were greater than 90% and approximately 97%, respectively. These results indicate that combining genotyping using a lower‐density SNP chip with genotype imputation based on a population of individuals genotyped using a higher‐density SNP chip is a cost‐effective and valid approach for genomic prediction.     

基于Panel Data模型的天津郊区城镇化对农民收入的影响研究

通过Panel Data模型,分析了天津郊区城镇化水平对农民收入的影响,并比较了郊区地区因素和时间因素对农民收入的影响.研究发现,天津郊区城镇化发展与农民收入水平之间存在长期均衡关系,但影响较小;地区和时间差异因素发挥了较为显著的作用.     

杨木-玻璃纤维复合板的物理力学复合效应

以三倍体毛白杨和玻璃纤维为主要原料，研制出三种不同组合形式的木材玻璃纤维复合板并分析了板的物理力学复合效应。结果表明：与普通PF树脂杨木刨花板相比，该复合板的密度、抗弯强度、抗弯弹性模量得到很大提高，内结合强度略有降低，吸水厚度膨胀率有增有减。     

脲醛树脂在水曲柳刨切薄木湿贴工艺中的应用

扼要介绍了湿法棉秆中密度纤维板基材表面用以脲醛树脂为主要成分的混合胶,湿贴厚度为0.25mm和0.4mm水曲柳刨切薄木的工艺,并对基材、胶粘剂、贴面材、胶贴工艺等诸多因素优化研究,比较有效地解决了透胶和脱胶等问题,制得质量合格而又有明显经济效益和使用价值的棉秆中密度纤维板薄本装饰板。研究结果表明,湿贴工艺中采用以脲醛树脂为主要组分的混合胶是可行的,胶贴质量达到日本农林省JAS标准“装饰合板”中规定的指标。     

Cause and Consequence in Maize Planting Dates in Germany

An important part of agricultural adaptation is the timing of crop sowing dates, affecting yields and the level of risk incurred during a particular season. Cold stress is especially relevant in maize, Zea mays L., so that the timing of planting in the spring is a tactical response to short‐term weather, but is also subject to strategic planning with regard to longer‐term climate. Both factors compare the potential implications of cold stress to the additional yield obtainable through earlier planting. New cultivars suited to growing conditions in Europe and generally increasing spring temperatures have enabled earlier planting, but it is still dependent on short‐term weather during the planting period. In the context of field‐level decision‐making, a panel regression is used to estimate the relationship between weekly local temperature and precipitation and planting dates at specific sites throughout Germany. Next, localised weather data and planting behaviour are linked to yields at the district (Landkreis) level to show the effects of planting date on yield. Based on these relationships optimal planting dates are explored with some associated costs and benefits. Results show a trend towards earlier planting that follows observed increasing spring temperatures and the availability of more cold‐tolerant cultivars but this advance is buffered by the increasing severity of minimum temperatures during a critical period. Earlier planting potentially increases yield but this is offset by additional management costs and risk. A robust and simple depiction of farmer behaviour in climatic, technological and economic context can help to understand trends in crop management and productivity that effect agricultural landscapes.     

5·15绥化局部强风致房屋破坏调查分析

结合现场调查结果,介绍并分析了绥化局部强风区附近建筑物受风灾影响现象。得到以下主要结论:一些按照国家现行规范设计的建筑物可以抵抗超限的水平风荷载和屋面吸力;但是,未经设计自建的农村民宅,在大风作用下其结构或围护结构就会产生严重的破坏。砖木结构的破坏主要表现为围护结构整体受损和山墙倒塌。屋面的抗风能力与屋面材料有关。传统的土坯房及一面清房屋在强风作用下整体倒塌。强风导致供电线路、通讯线路的毁损带来重大经济损失。     

2000-2017年中国农村水资源贫困与经济贫困的耦合协调状态及其影响因素

[目的] 测算中国农村水资源贫困指数和经济贫困指数的耦合度和耦合协调度,为减轻农村水贫困与经济贫困提供理论依据和政策启示。[方法] 以中国31个省（市、区）为研究对象,运用层次分析法、熵值法、系统耦合协调度模型、空间杜宾面板数据模型等方法,研究了2000—2017年农村水资源贫困与经济贫困耦合协调度的时空分布特征和影响因素。[结果] ①从整体来看,虽然中国农村水资源贫困与经济贫困的耦合协调度不高,但大致呈上升趋势,且中国31个省（市、区）均表现为耦合度大于耦合协调度。②就空间角度而言,中国农村水资源贫困与经济贫困的耦合协调度呈现由东南部向东北、西南部扩散的态势,东部沿海地区的江苏和浙江、南部沿海地区的福建与广东、地处长江中游地带的湖南省的耦合协调度最高。③农村水资源贫困与农村经济贫困耦合协调程度存在明显的负向溢出效应。财政农林水事务支出对农业生产具有较大的促进作用,而农产品价格和第二、三产业比例提高会抑制其发展。[结论] 国家应加大或维持对农村原有的财政支持力度,充分发挥政府和市场在资源配置中的调节作用。合理调整农产品价格的同时,加大农业技术投入,加强地区间分工合作,促进产业升级,从而推保农村水资源与农村经济协调发展。     

良好农业规范(GAP)在蔬菜基地中的应用——基于面板数据和语言信息的农产品安全评价

针对良好农业规范(GAP)在蔬菜种植基地实施中,审核专家的评价信息仅做简单汇总而没有进行充分利用和分析,语言评价信息易损失和扭曲、限于平面数据集结等问题,以山东省6个备案蔬菜种植基地2001-2006年期间的评价为例进行了实证研究.提出了一种基于语言信息和面板数据的综合评价方法,据GAP标准构建了蔬菜基地的农产品安全评价指标体系,统计了GAP审核专家就6个基地的评价信息,对信息分别进行多指标和时序加权集结,得到各基地的综合评价结果,并对结果进行分析,充分利用评价信息,用以指导基地在GAP实施中的改进.研究表明以上方法可以有效地将语言评价信息进行集结,避免信息损失,并能够体现决策者对不同时期的重视程度.该方法将促进良好农业规范GAP标准的推广和应用,实现农产品安全管理的目标.     

橡胶树死皮防治缓释颗粒调理剂造粒工艺的研究

橡胶树死皮已成为制约天然橡胶生产发展的重要因子之一,研发轻简、高效的死皮防治技术是目前橡胶生产中亟需解决的问题。以腐植酸为载体,对橡胶树死皮防治缓释颗粒调理剂的圆盘造粒工艺进行了研究。通过设计正交试验,分析了圆盘倾斜角度、圆盘转速及粘结剂对缓释颗粒调理剂的粒度、颗粒强度及颗粒崩解率的影响,确定了合理的造粒工艺：圆盘转速为60 r/min、倾角30°,粘结剂为壳聚糖。最优工艺条件下制备的缓释颗粒调理剂的粒度为91.5%、颗粒强度为34.1 N、崩解率为10%,粒度及颗粒强度已达国家复合肥标准相关要求;从崩解率看,所制备的调理剂颗粒具有一定的缓释性能。本研究的开展可为实现轻简、高效的橡胶树死皮防控提供技术支撑。     

波浪高度及方向对桩柱式围网养殖系统网片水力特性的影响

浅海围网养殖是一种生态型养殖模式,桩柱式围网是其中最为典型的模式之一,主体由排桩和网片组成。围网网衣系统安全是决定围网工程安全的关键所在。针对桩柱式围网,采用数值模拟方法对其主要构成部件单元网片在波浪条件下的变形和受力等水力特性进行了研究,重点分析了波高(1、2、3、4、5 m)和波向(10°、30°、50°、70°、90°)条件下围网网片的网线张力分布、结节偏移和桩柱系缚点受力特性及影响关系。结果表明,桩柱式围网单元网片的网线最大张力部位主要出现在网片上端两侧位置,应用时建议强化顶部纲绳的设计考虑;波向为30°~70°时,网线最大张力有一段较小的增加量,而结节最大偏移随波向的增大而增大;网片与桩柱系缚点的最大受力呈现两端大中间小的现象,建议强化顶部和底部系缚点。以上研究结果可为桩柱式围网工程设计与安装提供参考。