Using vector analysis to understand temporal changes in understorey-tree competition in agroforestry systems

Techniques to determine the respective effects of resource limitation or over supply on tree productivity are important for developing effective forestry and agroforestry management strategies. There is a need for a simple integrative measure of the understorey effect on soil nutrient and moisture competition on tree productivity in agroforestry systems during the time period before trees dominate understorey vegetation. For the first time, the little used, but potentially valuable tool of vector analysis was evaluated over 5 years by investigating nutrient and water competition in a Pinus radiata silvopastoral experiment which had 5 pastures and a nil-understorey control. The study, from ages 2 to 6 years, was on fertile arable soils in a temperate, sub-humid climate. Establishing permanent crops on this arable site increased soil pH, C, N, organic-P and C:N ratio. Vector analysis, an analysis based on fascicle nutrient concentrations, dry weights and nutrient contents, predicted nutrient and moisture competition until the trees dominated the site after year 5. Foliar critical nutrient levels were helpful where one of the vectors was unable to distinguish between nutrient and moisture stresses. While moisture and N were found to be the main competitive factors, vector analysis also detected foliar nutrient accumulation, particularly for P and Mg. Lucerne and phalaris understoreys were the most competitive pastures, followed by cocksfoot and the two ryegrass treatments. Foliage vector analysis enabled the relative competitive effects of soil nutrients and moisture on tree productivity to be determined. Soil nutrient concentrations and soil moisture measurements and the effects of competition on tree growth were consistent with predictions from vector analysis.     

关于现行财务报告模式局限性的理性思考

财务报告的根本目标是决策效用性，但现行的财务报告模式未能充分、及时反映企业的财务信息和所面临的潜在风险，会计信息用户要求改进财务报告的呼声越来越高。本文作者分析了现行财务报告模式的局限性，并提出了若干可行性对策     

园林审美走向初探

分析了中国传统园林的局限性及其产生的根源，并从6个方面总结了园林审美走向的变迁。     

Techniques for objective outcome assessment

Companion animal rehabilitation, a collaborative practice of physical therapy and veterinary medicine, can only demonstrate the effectiveness of its theories, techniques, interventions, and modalities through evidence-based practice, utilizing standardized, reliable, and valid outcome measures, correlated with objective diagnostic data. This essay examines existing and potential objective outcome measures utilized in companion animal rehabilitation and physical therapy regarding pain, vital signs, body condition and composition, range of motion, muscle strength, inflammation, functional mobility, and gait. Discussion is included of the traditional disablement model and the evolution of the physical therapy diagnosis, prognosis, and plan of care.     

降水量对荒漠草原植物群落多样性和C:N:P生态化学计量特征的影响

基于2014年在宁夏荒漠草原设立的降水量变化的野外模拟试验平台(年均降水量减少50%、减少30%、增加30%、增加50%以及对照),研究了植物群落多样性和C:N:P生态化学计量特征的变化,并分析了二者间的关系。结果表明,减少降水量降低了白草(Pennisetum centrasiaticum)种群生物量,但对其他物种种群生物量和群落生物量无明显影响。适量增加降水量促进了多数植物生长,提高了Shannon-Wiener多样性指数和Patrick丰富度指数。但过量增加降水量抑制了苦豆子(Sophora alopecuroides)和猪毛蒿(Artemisia scoparia)生长、降低了Shannon-Wiener多样性指数;减少降水量对植物群落C:N:P生态化学计量特征影响较小。增加降水量降低了植物群落全碳、全氮和N:P;植物种群生物量与植物群落C:N以及土壤含水量存在较强的正相关关系,与植物群落全氮和全磷存在较强的负相关关系。植物群落多样性指数与土壤含水量、植物群落C:N以及土壤C:N存在较强的正相关关系,与植物群落全氮、全磷以及N:P存在较强的负相关关系。以上结果表明改变短期降水量荒漠草原植物群落组成不仅与土壤水分有效性密切相关,而且受植物N和P摄取能力的调控。     

竹在现代园林中的应用与发展

本文分析了中国古典园林中竹子的造景手法、审美价值和功能利用方面的特点及其局限性,结合世界现代园林的实践与理论,阐述了为满足尺度更广阔、内容更丰富、功能更齐全、技术更发达、审美更多样的现代园林的需要,现代竹子造景在表达方式、文化内涵和生态功能方面进行拓展的必要性,并对于新的竹子造景手法进行了归纳和探索。     

拉格朗日－达朗伯方程的普遍意义及不便求解的问题

拉格朗日－达朗伯方程是动力学普遍而统一的方程，是分析力学的基础，本文阐述了方程的普遍意义；指出了应用时的限定条件；用它推导建立了动力学３个普遍定理和机械能守恒定律；并探讨了方程的局限性和不便求解的问题。     

论我国知识产权反垄断立法

知识产权是法律赋予的合法垄断权，但如果知识产权人滥用其专有权，损害社会公共利益，就必须受到反垄断法的规制。我国迄今为止尚未出台反垄断法，对知识产权滥用的反垄断立法既缺乏系统性，也不具可操作性。本文提出了我国知识产权反垄断立法的基本原则，阐述了知识产权反垄断立法的构架和规制对象，并提出我国知识产权反垄断的若干运行程序。     

CRISPR/Cas9基因编辑技术在植物中的应用与政策监管

基因编辑技术是一种在基因组水平上对DNA序列进行精准修饰,从而促使基因组序列定向改造的技术。随着近几年CRISPR/Cas9技术的快速发展,基因组编辑技术在作物育种领域发挥了越来越重要的作用。本文综述了基因编辑技术的发展历程,以及CRISPR/Cas9的工作原理,分析了CRISPR/Cas9的局限性并提出了改进方法。重点阐述了植物CRISPR/Cas9基因编辑体系的建立、在植物性状改良方面的应用,以及最终致力于基因编辑产品商业化的应用案例。同时还分析了美国、欧盟、英国、日本和中国这5个代表性国家/地区的基因编辑监管政策和态度,以期为我国科学监管框架的建立提供参考,促进CRISPR/Cas9在我国乃至全球的产业化应用。     

新农村建设中“空心村”的整治

在新农村建设中,一些地方村容的整治,加剧了村内大片土地的闲置和村庄向外围的无序扩张,出现严重的"空心村"现象。"空心村"延缓人居环境的改善,影响农村精神文明建设,阻碍农业发展,浪费耕地;新农村建设应与"空心村"治理结合起来,通过完善农村土地管理制度、整治旧村与规划新村等途径整治空心村,促进新农村建设。