The coconut pathosystem: weed hosts of nymphs of the American palm Cixiid Haplaxius crudus (Hemiptera: Fulgoroidea)

Lethal yellowing (LY) of coconut palm (Cocos nucifera L., Arecaceae) is a disease of economic importance that is caused by the phytoplasma ‘Candidatus Phytoplasma palmae’ and is transmitted by the planthopper Haplaxius crudus (Van Duzee) (Hemiptera: Cixiidae). This study explores the weeds used by H. crudus nymphs and other Cixiidae in a coconut pathosystem in southern Mexico. Nymphs were collected directly from the root system of each weed by hand or with the help of a vacuum after carefully opening the culm. This study included 11 species of weeds: nine Poaceae [Brachiaria decumbens Stapf, B. humidicola (Rendle) Schweick, B. mutica (Forssk.) Stapf, Digitaria abyssinica (Hochst. Ex A. Rich.) Stapf, Eustachys petraea (Sw.) Desv., Leersia hexandra Sw., Panicum laxum Sw., P. maximum Jacq., Paspalum notatum Flüggé]; one Cyperaceae [Cyperus ligularis L.], and one Portulacaceae: [Portulaca pilosa L.]. Brachiaria mutica, E. petraea, B. humidicola, P. maximum were identified as the principal host species for H. crudus nymphs. Brachiaria decumbens, D. abyssinica, and C. ligularis are new host records for the nymphs of H. crudus. Additionally, it was found that H. crudus may coexist with its cogeners H. skarphion Kramer (Cixiidae) and H. caldwelli Kramer (Cixiidae), on B. mutica. On C. ligularis, H. crudus may coexist with Oecleus snowi Ball (Cixiidae) nymphs. These results suggest that in the coconut pathosystem there is a complex of multitrophic interactions that should be considered in integrated management of LY.     

在极低温下照射种子的生物学效应 Ⅲ·液氮低温的刺激增产和诱变作用

基于极低温对种子γ辐射效应的影响,研究了液氮低温(-196℃)单因子的生物学效.发现液氮处理冬小麦风干种子,不仅有损伤效应,也有刺激增产和诱变作用.实验结果表明:在液氮中进行种子γ照射应考虑这些因素,并对发展中的低温生物学也提出了有待研究的新问题.     

基于行人运动模型的人群疏散三维仿真

以人群运动过程中人与人和人与建筑之间的相互作用为出发点,探讨了行人群集行为疏散模型及三维仿真问题.建立了一种基于人员行为细节的微观离散仿真模型,采用蒙皮动画和有限状态机技术实现对人物行为和人物模型细节状态的控制,可以实现人群疏散过程的动态三维可视化仿真.     

光固化快速成形中柱形支撑生成算法的研究

提出了光固化快速成形中一种新的工艺支撑形式——柱形支撑及其自动生成算法．其算法思想为：在零件的包容立方体内确定支撑生成点的布点规则以后,对于零件的每个三角面片,求出与其相关布点射线的交点,再由这些交点在三维空间内直接生成柱形支撑的中心线段,而后生成STL格式的柱形支撑实体．该算法生成柱形支撑的速度快,可实现实时模拟,快速观察生成效果,已成功应用于光固化快速成形系统中．     

Novel l_2-l_∞ controller design for LPV discrete time-delay systems

1.INTRODUCTION Manyreal worldsystemscanbemodeledaslinearpa rameter varying(LPV)systems[1],whosestate spacerepresentationmatricesarefunctionsofasetof parametersthataremeasurableinrealtime.Recent ly,manyresearchersathomeandabroadhavebeen engagedinthestabilityanalysisandgainscheduling controlofLPVsystemsextensivelyandagreatnum berofimportantresultshavebeenreportedinthelit erature(see,forinstance,Refs.[1～7]andtheref erencestherein).Mostoftheseresultsfocusoncon tinuous timecases,while…     

Novel Newton’s learning algorithm of neural networks

1 .INTRODUCTIONBP methodis a widely used classical learning algo-rithmof Neural Networks . Whileit has two short-ages ,i .e .slowconvergence rate and existinglocalmini mum of the cost function. Many new algo-rithms such as modification methods of BP meth-od, conjugate gradient methods , RLS methods ,quasi-Newton methods , evolving learning meth-ods ,chaos-learning algorithms have been proposedso far[1 ~7]. However ,these novel algorithms neverdirectly utilize the 2-ed order differentia…     

Biological properties of 4-amino-5 alkyl-sulfone substituted orthoanisamides]

The 4-amino 5-alkyl-sulfone substituted orthoanisamides can be distinguished from their non-aminated homologues (sultopride) or sulfamoyl homologues (sulpride) mainly by the intensity of their anti-emetic effects with regard to apomorphine and their mode of action, either on hippocampic rhythms or on locomotor rhythms in the Cat.     

Variation in the specific activity of intestinal DNA in Alytes obstetricians larvae (Amphibia, Anura) treated with thyroxine]

Treatment by thyroxine modified the specific activity of intestianl DNA in premetamorphic Alytes tadpoles. The activity decreased up to the 3rd day, and showed afterwards a peak which culminates on the 9th day. These results have been discussed in comparison with previous radioautographic observations.     

中国青年科技奖设奖20周年成效卓著

1987年,在时任中国科协主席钱学森院士的提议下,中国科协设立\"中国科协青年科技奖\",以鼓励青年科技工作者奋发进取,促进青年科技人才健康成长。     

Web服务对等联盟组织演化机制

为提高分布式非结构化对等网络中Web服务发现的效率和稳定性,设计了一种以Web服务提供者的服务内容为评价依据的对等联盟演化机制.根据该机制,服务提供者依据各自提供的Web服务内容之间的相似程度,自发形成联盟.每个提供者维护的同盟表用来保存部分盟友列表,从全局形成服务联盟.服务提供者根据盟友关系将Web服务的描述信息发布...