Using traffic flow theory to model traffic mortality in mammals

Traffic has a considerable effect on population and community dynamics through the disruption and fragmentation of habitat and traffic mortality. This paper deals with a systematic way to acquire knowledge about the probabilities of successful road crossing by mammals and what characteristics affect this traversability. We derive a model from traffic flow theory to estimate traffic mortality in mammals related to relevant road, traffic and species characteristics. The probability of successful road crossing is determined by the pavement width of the road, traffic volume, traversing speed of the mammals and their body length. We include the traversability model in a simple two-patch population model to explore the effects of these road, traffic and species characteristics on population dynamics. Analysis of the models show that, for our parameter ranges, traffic volume and traversing speed have the largest effect on traffic mortality. The population size is especially negatively affected when roads have to be crossed during the daily movements. These predictions could be useful to determine the expected effectiveness of mitigating measures relative to the current situation. Mitigating measures might alter the road and traffic characteristics. The effects of these changes on traffic mortality and population dynamics could be analysed by calculating the number of traffic victims before and after the mitigating measures. This revised version was published online in July 2006 with corrections to the Cover Date.     

引诱剂在综合防治桔小实蝇作用中的评估

以使用引诱剂为主 ,坚持在杨桃园挂引诱笼 2 - 3年后 ,大量降低田间桔小实蝇BactroceradorsalisHendel雄虫数量和卵的受精率 ,配合其它的综防措施 ,防效逐年提高。三个综防点试验实践表明 :杨桃每果虫口数 ,卵孵化率及受害果率大大降低 ,防效达 92 5%。对桔小实蝇的防治初见成效。     

毒死蜱和甲氰菊酯对蜜蜂毒性与安全评价研究

通过接触法和摄入法测定了毒死蜱和甲氰菊酯对蜜蜂的毒性。结果表明，毒死蜱和甲氰菊酯对蜜蜂的接触毒性(24h LD50)分别为0．1634μg／蜂和0．0501μg／蜂，胃毒毒性(24h LE50)分别为0．6406mg／L和7．8261mg／L。根据Atkins毒性等级划分标准，毒死蜱和甲氰菊酯对蜜蜂的毒性均为高毒，应禁止在蜜蜂活动区域使用。     

The effect of non-inversion tillage and light availability on dispersal and spatial growth of Cynodon dactylon

The invasive ability of Cynodon dactylon is dependent on self dispersal and on cultivation practices. Tillage can seriously change patch biomass and spatial structure, spreading vegetative propagules of the weed. The objectives of this study were: (i) to quantify the effect on non‐inversion tillage on dispersal, establishment and colonization of C. dactylon and (ii) to propose a simple model considering soil cultivation effects and light availability on spatial growth of weed patches. Two experiments were carried out, exploring different soils and environmental conditions. Spatial distribution of vegetative units differed when tillage was conducted with different non‐inversion implements and could be described by simple functions. A minimum patch biomass seems necessary before vegetative structures are vulnerable to movement by cultivation. Only a small proportion of the biomass dispersed from original patches was able to establish. However, simulation showed that the area colonized by C. dactylon mostly increased by means of tillage dispersal, both with and without crop competition, in one growing cycle. It appears sensible to consider changing cultivation practices to reduce weed dispersal and to use crop competition for light to create unsuitable habitats limiting weed colonization.     

退耕还草产业化技术经济效果评价方法探讨

以平凉市退耕还草产业化技术开发为例,以产业化系统链中各子系统间的功能协调统一为依据,以退耕还草产业化机制为纽带,在研究建立平凉市退耕还草产业化技术经济效果包括4个一级指标(基础指标、配套指标、服务指标和效益指标)和17个二级指标体系的基础上,采用层次分析法(AHP法)、隶属度函数法和综合效益指数法作为退耕还草产业化技术经济效果的评价方法.经比较得出:平凉市退耕还草产业化技术开发综合指数达到0.595 1,属初步产业化阶段,相对发展指数达到27.268%,年均产业化进步速度达到6.817%.     

优质肉鸡繁育体系的效益评估

近十多年来，我国优质肉鸡的生产方兴未艾，许多育种公司和科研院所不断推出新品系。为充分发挥新品系的遗传潜力，探求优质肉鸡最佳的繁育生产模式具有重要意义。由于不同的品系及其杂种后代在不同的性状上各有优缺点，很难用生产性能进行直接比较，而适合用育种规划的方法通过经济学指标进行评价。系统分析通过把生产系统抽象概念化并用数学手段模型化的方法，     

美系杜洛克种猪体尺、体重测定与体型评定研究

统计分析了2001年引进的新美系杜洛克种猪及繁殖后代在6月龄、12月龄、24月龄和36月龄四个阶段的体尺、体重数据，结合品种特征、体型外貌总结研究出杜洛克种猪的百分制评分及等级标准。     

137Cs示踪法在东北松嫩平原土壤侵蚀定量评价中的应用

根据不同退化程度草原和不同开垦年限农田土壤137Cs放射强度分析结果表明:与轻度退化草原相比,中度退化和重度退化中的137Cs放射强度分别下降了21%和52%。草原土壤开垦后,137Cs放射强度明显下降,开垦7年、15年、33年后,137Cs的放射强度分别只有轻度退化草原的37%、31%和26%。相关分析表明,伴随着土壤侵蚀的发生,土壤有机质含量、全N含量以及阳离子交换量下降。137Cs放射强度与土壤有机碳、土壤全N、交换性K和阳离子交换量呈极显著的正相关。     

Body weight growth Model of Datong Yak in Qinghai

Summary:This study was conducted to develop a suitable model for describing the growth pattern of the yak. The data used consisted of body weight records of 76 growing yak aged between 5 to 37 months. Three mathematical models were applied to describe the growth curves during this development period:①Y1=20.105 + 11. 250x-0. 526x2 ;used for describing the growth curve of yak aged 5 to 13 months;②Y2 = -359.687 + 49. 977x - 1. 249x2 ;used for animals aged 13 to 25 months;and ③Y3 = -833. 339 + 63. 772x - 1. 019x2 ;used for animals aged 25 to 37 months.