Park and neighbourhood environmental characteristics associated with park-based physical activity among children in a high-density city

Constructing and renovating urban parks is an effective strategy for high-density cities to satisfy residents’ needs for recreation in nature. Using Hong Kong as an example of a high-density city, the purpose of this study was to examine the associations of park and neighbourhood environments with park-based physical activity (PA) among children and examine the moderating effect of neighbourhood income in their relationships. A cross-sectional study was conducted in 32 urban parks in Hong Kong. Park-based PA and the park and neighbourhood environments were measured using systematic observation tools and the geographic information system. Neighbourhood income was extracted from the 2011 Hong Kong Population Census data on median household income. A total of 7,753 children were observed using urban parks for PA during the study. Children’s park-based PA was positively associated with the quality of supporting amenities, park safety, neighbourhood walkability, and neighbourhood quality, while the associations of park-based PA with the diversity of active facilities and park size were not significant. In addition, neighbourhood income moderated the associations of park-based PA with the diversity of active facilities, the quality of supporting amenities, neighbourhood walkability, and neighbourhood quality. These findings provide empirical evidence on the moderating role of neighbourhood socioeconomic status on the associations between park and neighbourhood environments and children’s park-based PA in a high-density city. With children’s needs for using parks for PA, our findings are beneficial for urban planners to renovate existing urban parks to enhance their utility for children living in high-density cities.     

基于植被指数时序动态的冬小麦氮素营养诊断方法

为构建冬小麦冠层临界植被指数时序模型,探究实时、无损诊断冬小麦全生育期氮素营养状况的可能性,基于冬小麦不同生育时期氮营养指数(nitrogen nutrition index,NNI)与相对产量的关系确定NNI临界值,并利用归一化红边植被指数(normalized difference red edge,NDRE)与NNI的定量关系确定临界NDRE值,进而以累积生长度日为时间驱动因子,利用双Logistic函数构建临界NDRE时序模型并用于诊断,且对诊断结果进行了验证。结果表明,NNI与冬小麦相对产量在不同生育时期均呈现明显的线性加平台关系(R²在0.76以上),在开花—灌浆期表现最好;NNI与NDRE呈显著的幂函数关系(R2在0.76以上),在孕穗—开花期表现最好;临界NDRE时序诊断模型在拔节后期、孕穗期、开花期的诊断精度较高;适期播种时冬小麦在180 kg·hm^-2施氮水平下整个生育期均处于轻微氮亏缺或氮适宜状态,为较优施氮量。适期播种时冬小麦氮素营养状况主要受施氮水平的制约;过晚播时受播期的影响,不同施氮水平下冬小麦全生育期均处于氮亏缺状态。综上,依据氮营养指数与相对产量所构建的临界NDRE时序模型能够较准确地实时诊断冬小麦不同生育时期的氮素营养状况,并为作物氮肥精确管理提供技术方法。     

我国远洋渔业发展现状、面临问题与对策浅析

从远洋渔业的概念和发展远洋渔业的目的与意义入手,对我国远洋渔业近40年来的行业发展进行了简要梳理。通过总结远洋渔业行业发展现状及面临的主要问题,结合新形势下我国面临的内外部环境条件,提出该行业未来发展的应对策略及相关建议。     

天祝县鸡产业发展现状及前景对策分析

鸡产业作为天祝县八大产业之一,资源环境优越,生产效益稳定,市场潜力大。坚持龙头企业打造引领,科学规划养殖布局,落实工作措施,可有力推动全县畜牧业高质量发展,持续巩固拓展脱贫攻坚成果,加快乡村振兴步伐。     

基于改进RRT算法的猕猴桃采摘机器人全局路径规划

为提高猕猴桃采摘机器人导航效率,提出一种基于采样状态实时引导随机树扩展的改进方法(Straight-RRT)。首先,针对传统RRT算法盲目搜索的问题,引入评价指数与阈值划分采样状态,根据采样状态决定采样节点的选取方式,实时引导随机树的扩展。其次,为增强算法对不同环境的自适应性及快速避开不规则障碍物,引入动态阈值并优化最近节点选择机制。最后对路径进行优化处理,去除路径冗余点并采用贝塞尔曲线平滑路径减小路径复杂度。基于棚架式猕猴桃果园环境进行路径规划实验,实验结果表明改进后算法在猕猴桃果园环境中具有更好的适应性及规划效率,为提高猕猴桃采摘机器人导航效率提供了解决方法。     

我国农村生活污水治理的现状分析和对策探究

随着我国“乡村振兴”“厕所革命”等国家战略的实施,我国农村生活污水的治理也越来越受到重视,但是农村生活污水不同于城市生活污水,它的治理在标准、模式、技术、运维等方面存在诸多问题。本文详细介绍了我国农村污水治理现状,针对全国不同地区农村生活污水处理工艺和典型案例,从处理技术、排放标准以及运维管理等方面进行了系统分析,重点论述了处理技术的优缺点,并结合农村自然的自净能力和面源污染的根本原因,提出了建立排放标准的合理前提,同时也介绍了智慧运维在农村生活污水处理中的积极作用。另外,根据农村居住分散、地势差异大的特点,强调了分散式处理的重要性,旨在从根本上解决农村生活污水收集难、处理复杂的难题,以生态处理模式实现美丽乡村建设。     

Longitudinal variation in fish species composition in the Angabanga river, Papua New Guinea with observations on the trophic status of certain fish species

Abstract– Longitudinal variation in fish species composition at various sites on the Angabanga river showed an increase in diversity from source to mouth and that only a few fish species occur at all sites. The fish assemblage of floodplain pool areas contained fewer species than the main channel and was dominated by two exotic species Oreochrornis mossambicus (Peters 1852) and Trichoguster pectoralis (Regan 1910). Most native fish species utilize invertebrates as a food source. The absence of indigenous detritus/substrate feeders in the Angabanga community may account in part for the success of the two introduced species on the floodplain.     

浅谈当前农技推广工作现状、问题与建议

随着市场经济发展需要,农技推广工作,只有适应新形势、创新新方法,才能推动农业科技的快速发展。分析了当前农业科技推广中的现状与存在问题,并提出几点建议,谨供参考。     

Regulation of C/N Interaction in Model Plant Species

Summary

Carbon (C) and nitrogen (N) metabolisms are two major metabolic pathways which have been intensively studied in plants. Both N and C metabolisms are tightly linked in numerous plant biochemical pathways. Therefore the C to N ratio has to be carefully regulated to ensure proper functioning of the huge metabolic network. In order to maintain a viable C/N status under a large range of growth conditions plants have evolved complex mechanisms to regulate the delicate network of these two major assimilatory pathways. C and N metabolisms are both highly regulated. We will present the current knowledge on the regulation of N and C metabolisms by sugars and N metabolites. Players involved in these regulatory processes are just starting to be uncovered and possible signaling molecules involved in these regulations as well as known or potential candidate regulatory genes willbe discussed.     

江门市与中国热科院广州实验站农业开发合作探讨

简述广东省江门市的农业产业发展概况、存在问题与科研院所合作现状。探讨中国热带农业科学院广州实验站与江门市合作的领域与前景,提出江门市现代农业发展模式的相关建议。