Chaos, strange attractors, and fractal basin boundaries in nonlinear dynamics

Recently research has shown that many simple nonlinear deterministic systems can behave in an apparently unpredictable and chaotic manner. This realization has broad implications for many fields of science. Basic developments in the field of chaotic dynamics of dissipative systems are reviewed in this article. Topics covered include strange attractors, how chaos comes about with variation of a system parameter, universality, fractal basin boundaries and their effect on predictability, and applications to physical systems.     

剪叶对小棚漂浮育苗烟苗性状的影响

不同剪叶程度对小棚漂浮育苗烟苗的茎高、株高、茎粗、花期均有影响。研究表明,随剪叶程度的加重,烟苗株高、茎高和茎粗均呈下降趋势;剪叶有抑制烟草早花的作用。     

机械CAD中的通用3D自由曲面造型技术

利用曲面网格的边界曲线直接定义３Ｄ曲面，既能保证曲面的光滑过渡，即Ｃ＾１连续，又可避免通过确定扭矢来达到控制曲面的复杂计算。本文的方法不依赖于任何ＣＡＤ支撑环境中的曲面造型机制，具有极好的通用性，文中给出了应用实例。     

Surface expression of HLA-E, an inhibitor of natural killer cells, enhanced by human cytomegalovirus gpUL40

The nonclassical major histocompatibility complex (MHC) class I molecule HLA-E inhibits natural killer (NK) cell-mediated lysis by interacting with CD94/NKG2A receptors. Surface expression of HLA-E depends on binding of conserved peptides derived from MHC class I molecules. The same peptide is present in the leader sequence of the human cytomegalovirus (HCMV) glycoprotein UL40 (gpUL40). It is shown that, independently of the transporter associated with antigen processing, gpUL40 can up-regulate expression of HLA-E, which protects targets from NK cell lysis. While classical MHC class I molecules are down-regulated, HLA-E is up-regulated by HCMV. Induction of HLA-E surface expression by gpUL40 may represent an escape route for HCMV.     

Divalent metal nanoparticles

Nanoparticles can be used as the building blocks for materials such as supracrystals or ionic liquids. However, they lack the ability to bond along specific directions as atoms and molecules do. We report a simple method to place target molecules specifically at two diametrically opposed positions in the molecular coating of metal nanoparticles. The approach is based on the functionalization of the polar singularities that must form when a curved surface is coated with ordered monolayers, such as a phase-separated mixture of ligands. The molecules placed at these polar defects have been used as chemical handles to form nanoparticle chains that in turn can generate self-standing films.     

工农－5型手扶拖拉机手把振动的测试分析及评价

通过理论分析和振动测试，探索了工农－５型手扶拖拉机手把振动主要振源及其振动特性，并根据国际标准ＩＳＯ５３４９进行了振动评价，发现手把振动的主要激励源是发动机。研究结果为手拖手把减振装置的研制提供了理论依据。     

柿果实脱涩机理及脱涩技术研究进展

随着人们对柿果实保健功能的深入认识,柿树栽培面积和产量逐年上升。但中国在柿采后生理尤其是涩柿脱涩机理及相应技术的研究仍滞后于产业发展的需要,是制约目前柿产业发展的关键问题之一。本文综述了柿不同类型果实脱涩机理及涩柿采后脱涩技术及相关影响因子,旨在为相关研究和产业发展提供参考。     

Grain Yield Mapping: Yield Sensing,Yield Reconstruction,and Errors

Research findings are reviewed focusing on yield sensing methods, yield reconstruction, mapping, and errors. Yield sensing methods were explained and yield mapping process was briefly introduced. Grain flow through different combines was explained and the effects of combine dynamics on yield measurement accuracy were discussed. Other errors caused by various sensors that are utilized by a yield monitor were included. It was concluded that with proper installation, calibration, and operation of yield monitors, sufficient accuracy can be achieved in yield measurements to make site-specific decisions. Nevertheless, attention must be paid when interpreting yield maps since yield measurement accuracy can vary depending upon the measurement principle, combine grain flow model, size of management area chosen, and the operator's capabilities and carefulness in following instructions to obtain the best accuracy possible under varying field operating conditions. Some of the errors can be filtered out by careful analysis of the raw yield (or flow rate) data provided by yield monitors. Researchers have focused on crop flow models to improve yield reconstruction process. A yield reconstruction algorithm that effectively handles non-linear combine dynamics has not been developed by researchers yet. More efforts towards yield reconstruction should be encouraged.     

Coffee production and household dynamics. The popolucas of Ocotal Grande, Veracruz

Feminist anthropologists have evidenced the social and cultural aspects of motherhood and have challenged the universality of the nuclear family as the basis for residential and child-rearing practices. From a feminist anthropological perspective, the concept of the household has thus been redefined to capture the ways in which different principles of household recruitment and residence shape the activities and access to resources of women and men of different ages and status. This paper examines the relationship between household composition and coffee production in Ocotal Grande, a Popoluca community in the Sierra de Santa Marta in Southern Veracruz, Mexico. It shows that polygamous households are larger and have higher yields of coffee than other types of households. However, this does not mean that all members of the household profit equally from their contribution to coffee production. While some relationship exists between labor input and returns, the distribution of benefits is based on gender and age hierarchies and is open to conflict and dispute. This revised version was published online in June 2006 with corrections to the Cover Date.     

论乡村振兴的普遍性与特殊性

乡村振兴的普遍性在于可行性前提下的普遍性,在于百花齐放的普遍性。乡村振兴的 特殊性在于宽范围之中的可行性,在于可发展类型的特色性。运用马克思主义的矛盾分析方 法,处理普遍与特殊的辨证关系,普遍寓于特殊,特殊内含普遍,乡村振兴鼓励特色发展,特色模 式值得普遍推广但又要注意特殊普遍化,以助力乡村振兴的可持续发展。     

Dipolar antiferromagnetism and quantum criticality in LiErF₄

Magnetism has been predicted to occur in systems in which dipolar interactions dominate exchange. We present neutron scattering, specific heat, and magnetic susceptibility data for LiErF(4), establishing it as a model dipolar-coupled antiferromagnet with planar spin-anisotropy and a quantum phase transition in applied field H(c|| = 4.0 ± 0.1 kilo-oersteds. We discovered non-mean-field critical scaling for the classical phase transition at the antiferromagnetic transition temperature that is consistent with the two-dimensional XY/h(4) universality class; in accord with this, the quantum phase transition at H(c) exhibits three-dimensional classical behavior. The effective dimensional reduction may be a consequence of the intrinsic frustrated nature of the dipolar interaction, which strengthens the role of fluctuations.     

身份认证技术在电子商务信息安全中的应用

随着计算机、通信和国际互联网技术的不断发展,基于Internet的国际间的商务活动变得越来越普及.由于Internet技术的互联性、开发性和通用性,其电子商务的信息安全问题也变得日益严重,并成为目前研究的一个热点问题.各种身份认证技术也在不断出现并已广泛应用于军事、公安和公民身份认证等领域.由于身份认证采用不同的技术和方法,其安全性和适用环境不同,本文对在电子商务信息安全中进行身份安全认证应用的各种方法给出一个综合对比分析.     

论水文系统混沌特征的研究方向

简要介绍了混沌的概念，回顾了水文系统的混沌研究进展，从哲学上论证了水文系统混沌演化的普遍性，指出当前水文系统混沌研究的重点应该是探索水文系统混沌演化的普遍性，揭示水文系统混沌演化的成因机理和基本规律及其因果关系，提出了宏观、中观和微观时空尺度相结合，理论分析和计算机模拟相结合的水文系统混沌研究方法，讨论了形成混沌水文学的可能性     

阆中市嘉陵江北岸硬质防洪堤景观改造设计研究

结合国内防洪堤景观改造实例,将刚性防洪堤常见改造手法总结为三大类———以攀援植物、悬垂植物覆盖防洪堤表面,局部改造硬质防洪堤为可种植空间,以及整体堤面"生态外衣"的再造,并对每种处理手法的适用情况及优劣势进行分析。在此基础上,以阆中市防洪堤为例,针对其普遍性与特殊性,找到适合它的经济、科学、可行的实施方案。     

论生态系统的目的

在分析了目的论的演化、定义及其普遍性的基础上,进一步讨论了群落、种群、个体3个层次熵的变化,认为生态系统的目的是使其熵减小。     

Potato virus Y in the Russian Far East (epidemiology,strains, and damage)

Biological, physical, chemical, and antigenic characteristics of a potato virus Y are investigated. Significant strain diversity of this pathogen is found in the Far East of Russia. There are ten strains affecting potato and weeds. It is shown that PVYntm strain has a remote immunochemical affinity with common PVY strain. In the Far East of Russia, the most widespread aphid vectors of this virus are Myzus percicae Sulz., Aulacorthum solani Kalt., and Aphis gossypii Glov.     

内蒙古兴和县低山丘陵立地类型划分与林草适宜性评价

为了解半干旱区宜林荒山合理利用方式,于2016年7月和8月对兴和县低山丘陵造林地进行立地类型划分与林草适宜性评价。通过对38个样地的油松Pinus tabulaeformis树高和草本植物地上部分生物量进行多元线性回归分析,结果表明:影响油松生长的主导因子包括土壤厚度和平均土壤含水率,影响草本生物量的主导因子包括表土含水率、表土全氮质量分数、表土全磷质量分数和土壤砾石含量。通过单因素方差分析,选取和验证了地貌、地形、坡向、土壤质地、土层厚度、砾石含量作为立地划分因子,最终将研究区荒山荒坡造林地划分出8种立地类型。林草适宜性评价结果表明:第1级的立地同时适宜油松和草本植物的生长;第2级的立地较适宜油松生长,但不适宜草本植物生长;第3级的立地较为适宜草本植物生长,油松生长状况略差;第4级的立地不适宜油松生长,但草本植物生长稍好。根据各立地类型情况提出相应的林草措施建议。     

Protein, DNA, and virus crystallography with a focused imaging proportional counter

A set of programs has been developed for rapid collection of x-ray intensity data from protein and virus crystals with a commercially available two-dimensional focused geometry electronic detector. The detector is compact and portable, with unusually high spatial resolution comparable to that used in oscillation photography. It has allowed x-ray data collection on weakly diffracting crystals with large unit cells, as well as more conventional "diffractometer-quality" crystals. The quality of the data is compared with that from oscillation photography and automated diffractometry in the range of unit cells from 96.3 to 383.2 angstroms. Isomorphous and anomalous difference Pattersons, based on detector data, are shown for a variable surface glycoprotein mercury derivative and for a repressor-DNA bromine derivative, which has been solved at 7 angstroms with detector data only.     

幽默语对格赖斯会话合作原则的背离及功效

G rice提出的话语合作原则作为一种会话准则,在一定程度上具有普遍性。然而,不同的社会和文化可能具有其独特的会话交往规则。幽默是文学的一种表现形式,是人类文化成果之一。一般来讲,幽默较含蓄、深沉,容易背离G rice的会话合作原则。     

高等植物光系统Ⅰ的研究(Ⅰ)──叶绿体中存在两种光系统Ⅰ

用含有ＰＥＧ的提取介质有效地提取和分离了油松、毛白杨、豌豆及菠菜的类囊体膜片，经改进了的增溶方法增溶光合色素蛋白复合物，有效地、完整地将ＰＳＩ从膜结构上溶解下来．溶解液经ＤＯＣ ＰＡＧＥ分离，均可得到迁移率相近的具光系统Ⅰ活性的两条稳定的绿带，经超速离心及不同浓度毛地黄皂苷和Ｔｗｅｅｎ ２０处理，证明它们是两种ＰＳＩ，称为ＰＳＩ １和ＰＳＩ ２．ＳＤＳ ＰＡＧＥ分析证明这两种复合物多肽种类相同，部分多肽的组成在比例上存在差异，证明在高等植物中存在两种ＰＳＩ，而且这种存在具有一定普遍性