Selection and hydroponic growth of bread wheat cultivars for bioregenerative life support systems

As part of the ESA-funded MELiSSA program, the suitability, the growth and the development of four bread wheat cultivars were investigated in hydroponic culture with the aim to incorporate such a cultivation system in an Environmental Control and Life Support System (ECLSS). Wheat plants can fulfill three major functions in space: (a) fixation of CO₂ and production of O₂, (b) production of grains for human nutrition and (c) production of cleaned water after condensation of the water vapor released from the plants by transpiration. Four spring wheat cultivars (Aletsch, Fiorina, Greina and CH Rubli) were grown hydroponically and compared with respect to growth and grain maturation properties. The height of the plants, the culture duration from germination to harvest, the quantity of water used, the number of fertile and non-fertile tillers as well as the quantity and quality of the grains harvested were considered. Mature grains could be harvested after around 160 days depending on the varieties. It became evident that the nutrient supply is crucial in this context and strongly affects leaf senescence and grain maturation. After a first experiment, the culture conditions were improved for the second experiment (stepwise decrease of EC after flowering, pH adjusted twice a week, less plants per m²) leading to a more favorable harvest (higher grain yield and harvest index). Considerably less green tillers without mature grains were present at harvest time in experiment 2 than in experiment 1. The harvest index for dry matter (including roots) ranged from 0.13 to 0.35 in experiment 1 and from 0.23 to 0.41 in experiment 2 with modified culture conditions. The thousand-grain weight for the four varieties ranged from 30.4 to 36.7 g in experiment 1 and from 33.2 to 39.1 g in experiment 2, while market samples were in the range of 39.4–46.9 g. Calcium levels in grains of the hydroponically grown wheat were similar to those from field-grown wheat, while potassium, magnesium, phosphorus, iron, zinc, copper, manganese and nickel levels tended to be higher in the grains of experimental plants. It remains a challenge for future experiments to further adapt the nutrient supply in order to improve senescence of vegetative plant parts, harvest index and the composition of bread wheat grains.     

中国旅游业的发展特征与趋势研究

中国旅游业经过高速成长,已成为国民经济的一个重要产业,目前具有资源开发的宽泛性与不均衡性、产品供给的基本适应性与多样性、市场的巨大性与消费的普遍性、要素配套的失衡性、新业态萌动的蓬勃性、目的地产业的聚集性与发展的区域性、政府旅游管理决策认识的科学性等发展特征,发展趋势是产业地位和作用强化、产业结构合理化和高度化、产业组织集团化、管理法制化和规范化、发展生态化和可持续化、支撑科技化、盈利模式复合化.在国内外相关条件不断提高和改善的环境下,中国的旅游业将会迎来一个新的快速发展的阶段.     

Statistical modelling of radio wave propagation under sporadic E-Layer influence

A technique of modelling the one-hop radio wave propagation at middle latitudes in the presence of sporadic E-Layer is presented. The technique is focused on the performance of the long-term forecast of the maximum usable frequency range and on the increase of the radio communication reliability. Examples of calculation for medium-distance paths are shown.     

看红色文化如何与动漫经济相结合——动画电影《西柏坡》简评

时下红色文化热,唱红歌活动大江南北如火如荼。红色电影《西柏坡》将红色文化教育、红色旅游经济与动漫传播相结合,是一次用动画形式弘扬红色文化的大胆尝试。     

社会主义市场经济与系统工程

在阐述几个工业发达国家采用市场经济与政府干预的特点后，提出了构成我国市场经济体制的结构框架。并指出，在研究社会系统工程问题时，应以“人”为核心，运用系统工程的观点和方法研究我国市场经济体制的形成，并用混沌理论研究市场经济的演化过程。     

湖南省区域经济点轴式开发的优化分析

点轴开发模式已成为区域经济开发的主导模式。但湖南省原有的点轴设置暴露出扩散和带动作用不强、经济整体水平不高、两极分化现象明显等问题，究其原因是现行的点轴开发模式中“点”与“轴”的确定还不尽科学，开发过程中的具体操作还不尽完善，亟待进一步优化。从增强湖南区域经济开发中“点”与“轴”选择的科学性出发，利用综合评价统计模型重新对湖南区域经济进行分析，制定了一级、二级“点”与“轴”的选择方案，构建了湖南“双核”型的一级增长极结构和“十”字型的一级增长轴格局，并针对具体操作过程中存在的问题提出了有效的优化措施与对策。     

发展循环经济势在必行

全球资源短缺、环境污染严重的严峻现状已引起全世界的普遍关注和重视,各国都积极探索节约资源和实现经济可持续发展的有效途径,循环经济作为一种全新的经济增长模式应运而生.对于我国而言,要全面建设小康社会、实现新型工业化,发展循环经济是我们的必然选择和必要出路.文章从循环经济的概念入手,分析了发展循环经济的必要性及其重要意义,指出发展循环经济的紧迫性并提出了几点有效的发展途径.     

奥运会对北京经济的挤出效应

举办2008年奥运会,是发展北京经济强有力的助推器,对北京经济具有巨大的提升作用.然而,奥运对北京经济同时也具有不利的影响--挤出效应.文章具体分析了奥运对北京经济的挤出效应,以便更好的利用这次机遇促进北京经济的进一步发展.     

我国东南沿海产业集群发展的机理

运用经济学理论对我国沿海地区产业集群发展的经验进行分析，结果表明，地区产业集群的形成是政府采取不平衡发展战略的结果，具有比较优势的主导产业又是形成产业集群网络式的、具有不断创新能力特征的主要依托，完善的市场运行机制、良好的投资环境是产业集群发挥极化效应、扩展效应和回程效应的基础，同时又是带动区域经济发展的动力。     

从大田视角探讨物流企业核心竞争力战略设计

从核心竞争力的内涵及特征入手,对大田集团现有核心竞争力进行识别和界定,运用SWOT矩阵分析大田集团的内外环境,在此基础上探讨大田集团核心竞争力战略的构建与展开,为中国物流企业在知识经济条件下如何设计核心竞争力战略、构筑国际竞争优势提供了一系列战略思考。