单纯疱疹病毒脑炎模型的研究

对单纯疱疹病毒(HSV)感染小鼠致病特点进行了观察,小鼠感染HSV第3天后开始发病,感染后第2天脑内可检测出病毒核酸,第3天脑内可分离出病毒,第4天病毒滴度达到高峰,发病2天内死亡。电镜观察感染鼠脑内组织出现超微结构改变,并可找到病毒颗粒。结果说明所建立的HSV脑炎模型可用于评价抗HSV药物。     

一类挖坑机械钻头横向振动系统的最优控制问题

建立了一类挖坑机械钻头横向振动系统的数学模型,并以阻尼函数作为控制变量,研究了该系统的最优控制问题,得出了两个定理。     

岷江上游乡村社区贫困成因及扶贫模式初探——以四川黑水国家扶贫开发重点县为例

农村发展包括乡村社区发展和农户发展两个方面 ,二者不能偏废。以岷江上游国家扶贫开发重点县———黑水为例 ,探讨乡村社区贫困成因及扶贫模式。社区贫困是多种因素长期综合作用的结果 ,包括自然环境条件、传统习俗与贫困文化结合、道路交通贫乏、森林资源利用政策以及落后守旧的农业生产技术和手段。乡村社区扶贫不同于区域扶贫 ,应以新村建设和易地迁建为主 ,辅以劳务输出、旅游开发和教育扶持。     

胶合板厂生产规划模型与运用

本文根据胶合板厂实际情况，建立了杨木胶合板厂生产规划模型。该模型考虑各主要设备工段、产品组合、产品混合、产品价格、流动资金、原材料供应以及市场约束等问题。本模型能够满足市场竞争，获取最佳利润，同时还能解决胶合板厂“三板”（表、背、芯单板）不平衡问题。     

西部少数民族贫困山区扶贫模式研究——以四川省昭觉县为例

西部民族贫困山区是我国扶贫攻坚的重点和难点地区,其扶贫工作的好坏直接关系：我国民族团结、全面建设小康社会目标的实现。在分析西部民族贫困山区县——四川省昭觉县农村贫困与扶贫工作现状的基础上,总结了适合民族贫困山区县的扶贫模式——“三集中”扶贫模式,提出通过发展县域循环经济和建立健全生态环境补偿机制来推广发展“三集中”扶贫模式的对策建议。     

Adjusting for heterogeneity of variance for carcass traits affects single and multiple trait selections in genetic evaluation of Japanese Black cattle

Heterogeneity of variance among subclasses of an effect is a potential source of bias in genetic evaluation. Degrees of the heterogeneity of variance among farm‐market‐year‐sex (FMYS) subclasses for carcass weight, beef marbling standard number, rib‐eye area, rib thickness and subcutaneous fat thickness were investigated in Japanese Black cattle. Consequences of adjusting for the heterogeneity on the predicted breeding values (PBVs) or on the genetic indexes derived from the PBVs of the five carcass traits were assessed. A total of 57 461 records were collected between 1997 and 2002 from steers and heifers fattened at farms across Japan. These records were grouped into 1591 FMYS subclasses. Bartlett's test showed that the degree of the heterogeneity of variance among the FMYS subclasses was sizeable in all traits (P < 0.0001). By applying a two‐step adjustment procedure it was possible to reduce the standard deviation, the coefficient of variation and the Gini coefficient of the phenotypic variances by 67.5% to 75.0% in the different traits. The applied adjustment caused a substantial re‐ranking of elite dams in the PBV for each trait as well as in the genetic index. This study provided evidence that the applied adjustment reduces the bias in the PBVs due to heterogeneous variances and increases the accuracy of bull‐dam selection.     

Genetic parameters for maternal behaviour traits in sows

Data from 32 nucleus and multiplier herds in Germany was used to estimate variance components and breeding values for five maternal behaviour traits in sows. The estimation was performed univariately using an animal threshold model. About 31,000 farrowings recorded from December 2003 until July 2005 were included. The heritability coefficients were 0.07 (0.06) for group behaviour, 0.06 (0.03) for attitude to people, 0.05 (0.01) for maternal ability, 0.03 (0.01) for crushing of piglets and 0.02 (0.02) for savaging of piglets. Additionally, genetic correlations between the behaviour traits and between the behaviour traits and litter size, respectively, were estimated multivariately by REML with a linear model. Low heritability and weak genetic correlation to litter size at birth indicate that it may be difficult to genetically improve the maternal behaviour, and that selection for better mothering ability is not necessarily accompanied by reduced litter size at birth.     

Effect of culling age of does on milk and meat production in Japanese-Saanen goats

A functional herd dynamics model was developed to estimate the effect of culling age on milk and meat production for Japanese-Saanen goats in relation to changes in prices of milk and meat. The model simulates life cycle production of bucks and does and their kids. Every production trait is first modelled as an individual trait and thereafter as a trait in the herd using a herd dynamics model. At the individual level, the survival curve function, the litter size function and the production traits function are combined. Data on growth and lactation were used to fit growth and lactation curves to estimated parameters using non-linear least squares regression technique and used in the production traits function. Using herd dynamics, the individual level functions are combined with the total number of animals function to estimate the total herd output and income efficiency at the herd level. Here, variables of culling days including the effect of difference in meat price value among goat categories (bucks, does, male kids and female kids) are used. Analysis of interrelations among the culling days of does, the price ratio and the income efficiency indicated that optimal culling days of does was shortened with an increase in the price ratio of meat to milk. However, when meat price value was different among goat categories according to actual situation of Japanese goat production, the optimal culling days of does could be fixed regardless of the change in price ratio and was calculated as 1730 days. This functional herd dynamics model can aid in decision-making regarding culling under several situations especially when there is a wide fluctuation in prices at local markets.     

Influence of habitat amount,arrangement, and use on population trend estimates of male Kirtland’s warblers

Kirtland’s warblers (Dendroica kirtlandii) persist in a naturally patchy environment of young, regenerating jack pine forests (i.e., 5–23 years old) created after wildfires and human logging activities. We examined how changing landscape structure from 26 years of forest management and wildfire disturbances influenced population size and spatial dispersion of male Kirtland’s warblers within their restricted breeding range in northern Lower Michigan, USA. The male Kirtland’s warbler population was six times larger in 2004 (1,322) compared to 1979 (205); the change was nonlinear with 1987 and 1994 identified as significant points of change. In 1987, the population trend began increasing after a slowly declining trend prior to 1987, and the rate of increase appeared to slow after 1994. Total amount of suitable habitat and the relative area of wildfire-regenerated habitat were the most important factors explaining population trend. Suitable habitat increased 149% primarily due to increasing plantations from forest management. The relative amount and location of wildfire-regenerated habitat modified the distribution of males among various habitat types, and the spatial variation in their abundance across the primary breeding range. These findings indicate that the Kirtland’s warbler male population shifted its use of habitat types temporally and spatially as the population increased and as the relative availability of habitats changed through time. We demonstrate that researchers and managers need to consider not only habitat quality, but the temporal and the spatial context of habitat availability and population levels when making habitat restoration decisions.     

马铃薯不同栽培模式比较试验初报

对马铃薯起垄铺膜双行、起垄不铺膜双行、起垄铺膜单行和起垄不铺膜单行4种不同栽培模式进行比较,筛选出适宜喀什地区马铃薯生产的最佳栽培模式为起垄铺膜双行栽培,该模式下的马铃薯产量高,品质好。