The future of ageing

Advances in our knowledge of age-associated diseases have far outpaced advances in our understanding of the fundamental ageing processes that underlie the vulnerability to these pathologies. If we are to increase human life expectancy beyond the fifteen-year limit that would result if today's leading causes of death were resolved, more attention must be paid to basic research on ageing. Determination of longevity must be distinguished from ageing to take us from the common question of why we age to a more revealing question that is rarely posed: why do we live as long as we do? But if the ability to intervene in ageing ever becomes a reality, it will be rife with unintended and undesirable consequences.     

The ecological cost of sex

Why sex prevails in nature remains one of the great puzzles of evolution. Sexual reproduction has an immediate cost relative to asexual reproduction, as males only express their contribution to population growth through females. With no males to sustain, an asexual mutant can double its relative representation in the population in successive generations. This is the widely accepted 'twofold cost of males'. Many studies have attempted to explain how sex can recoup this cost from fitness benefits associated with the recombination of parental genotypes, but these require complex biological environments that cycle over evolutionary timescales. In contrast, we have considered the ecological dynamics that govern asexual invasion. Here we show the existence of a threshold growth rate for the sexual population, above which the invasion is halted by intraspecific competition. The asexual population then exerts a weaker inhibitory effect on the carrying capacity of the sexual population than on its own carrying capacity. The stable outcome of this is coexistence on a depleted resource base. Under these ecological circumstances, longer-term benefits of sex may eventually drive out the asexual competitor.     

中国医药:何时现辉煌?

中医药是我国的国粹，但面临不 少问题与挑战。中医药需要与时俱进， 就需要中药现代化，通过技术创新，再 现中药的辉煌。     

CAI制作与展望

详尽阐述了CAI基础知识、设计原则、制作过程、注意问题和新型CAI展望 ,希望能够给广大教师提供一定的帮助     

Corex技术在中国的发展前景

熔融还原是新近发展起来的炼铁技术,Corex是唯一实现了工业化的熔融还原流程。它的主体能源是非焦煤,产品类似于高炉生铁。随着焦煤资源的日渐贫乏,焦炭供应将会越来越紧张,价格将会越来越高,非焦煤与焦炭的价格比将会越来越低。这一趋势将使熔融还原的经济效益越来越显著。因此,熔融还原生产的实现可为钢铁冶金环保和能源结构改善创出一条新路,对全国钢铁工业的可持续发展具有重大的意义。     

Corex技术在中国的发展前景

熔融还原是新近发展起来的炼铁技术,Corex是唯一实现了工业化的熔融还原流程.它的主体能源是非焦煤,产品类似于高炉生铁.随着焦煤资源的日渐贫乏,焦炭供应将会越来越紧张,价格将会越来越高,非焦煤与焦炭的价格比将会越来越低.这一趋势将使熔融还原的经济效益越来越显著.因此,熔融还原生产的实现可为钢铁冶金环保和能源结构改善创出一条新路,对全国钢铁工业的可持续发展具有重大的意义.     

The origins and the future of microfluidics

The manipulation of fluids in channels with dimensions of tens of micrometres--microfluidics--has emerged as a distinct new field. Microfluidics has the potential to influence subject areas from chemical synthesis and biological analysis to optics and information technology. But the field is still at an early stage of development. Even as the basic science and technological demonstrations develop, other problems must be addressed: choosing and focusing on initial applications, and developing strategies to complete the cycle of development, including commercialization. The solutions to these problems will require imagination and ingenuity.     

Internet对未来的影响

Internet是一个全球性的信息通讯网络，它的迅速发展和给人们带来的便利已经受到世人瞩目．本文介绍了Internet的工作原理、Internet上的语言和安全性等，并宕重讨论Internet对未来的影响．     

房地产营销:现在面临未来的挑战

房地产营销的管理是对未来的管理,这是可持续发展行业经营技术上的特征和要求 就未来的发展趋势论述了当前我国房地产行业的内在战略性问题,据此对房地产开发企业的战略规划提出建议     

论奥运竞技的性别平等取向

奥运竞技男女性别的平等化表现为项目设置与参赛人数的平等、决策与管理的平等、机会与资源的平等.平等化的趋向是人类文明的标志,是女性长期不懈斗争以及男性运动、管理权力不断妥协的产物,具有重大的社会和生命价值.由于历史的原因,目前人们在观念与操作层面上还存在着许多问题,有待于提高认识,促进竞技运动的进一步健康发展.     

混凝土坝冷却水管冷却效果研究现状及趋势

在混凝土坝中利用冷却水管中循环冷水来降低混凝土内部水泥的水化热温升,是混凝土坝温度控制的最有效措施。通过对混凝土坝开裂、裂缝的类型、产生的原因、危害和混凝土坝温度控制及冷却水管仿真计算研究现状的分析,论述了混凝土坝中冷却水管仿真计算的研究方向。     

股指期货套期保值模型选择

基于沪深300和S&P500的股指期货真实交易的数据,通过构建ETF组合作为沪深300的现货,选取S&P500的指数作为S&P500的现货,运用OLS,VECM,copula-VaR,修正的ECM-GARCH这4个模型进行套期保值的实证分析.通过"风险最小化"原则比较不同模型对于这2个股指的套期保值效率,发现以上4种方法对于沪深300的套期保值效率要优于S&P500;同时,对于2个股指,样本内和样本外都是动态的ECM-GARCH效果最优.最后给出投资者选择股指期货套期保值模型的具体建议.     

太阳空间探测的过去与未来

在简要回顾国际太阳空间探测历史的基础上,结合我国太阳空间探测的现状,重点阐述了我国天文界近年来开展太阳空间探测规划研究情况,并就未来发展,简要介绍了规划中拟开展的深空太阳天文台、先进天基太阳天文台、空间甚低频观测阵、立体观测太阳磁场、高分辨太阳X射线成像望远镜、以及空间站候选项目—高灵敏度太阳高能辐射探测等计划.