Molecular analysis of Neanderthal DNA from the northern Caucasus

The expansion of premodern humans into western and eastern Europe approximately 40,000 years before the present led to the eventual replacement of the Neanderthals by modern humans approximately 28,000 years ago. Here we report the second mitochondrial DNA (mtDNA) analysis of a Neanderthal, and the first such analysis on clearly dated Neanderthal remains. The specimen is from one of the eastern-most Neanderthal populations, recovered from Mezmaiskaya Cave in the northern Caucasus. Radiocarbon dating estimated the specimen to be approximately 29,000 years old and therefore from one of the latest living Neanderthals. The sequence shows 3.48% divergence from the Feldhofer Neanderthal. Phylogenetic analysis places the two Neanderthals from the Caucasus and western Germany together in a clade that is distinct from modern humans, suggesting that their mtDNA types have not contributed to the modern human mtDNA pool. Comparison with modern populations provides no evidence for the multiregional hypothesis of modern human evolution.     

Craniometric evidence for Palaeoamerican survival in Baja California

A current issue on the settlement of the Americas refers to the lack of morphological affinities between early Holocene human remains (Palaeoamericans) and modern Amerindian groups, as well as the degree of contribution of the former to the gene pool of the latter. A different origin for Palaeoamericans and Amerindians is invoked to explain such a phenomenon. Under this hypothesis, the origin of Palaeoamericans must be traced back to a common ancestor for Palaeoamericans and Australians, which departed from somewhere in southern Asia and arrived in the Australian continent and the Americas around 40,000 and 12,000 years before present, respectively. Most modern Amerindians are believed to be part of a second, morphologically differentiated migration. Here we present evidence of a modern Amerindian group from the Baja California Peninsula in Mexico, showing clearer affinities with Palaeoamerican remains than with modern Amerindians. Climatic changes during the Middle Holocene probably generated the conditions for isolation from the continent, restricting the gene flow of the original group with northern populations, which resulted in the temporal continuity of the Palaeoamerican morphological pattern to the present.     

Early dispersal of modern humans in Europe and implications for Neanderthal behaviour

The appearance of anatomically modern humans in Europe and the nature of the transition from the Middle to Upper Palaeolithic are matters of intense debate. Most researchers accept that before the arrival of anatomically modern humans, Neanderthals had adopted several 'transitional' technocomplexes. Two of these, the Uluzzian of southern Europe and the Chatelperronian of western Europe, are key to current interpretations regarding the timing of arrival of anatomically modern humans in the region and their potential interaction with Neanderthal populations. They are also central to current debates regarding the cognitive abilities of Neanderthals and the reasons behind their extinction. However, the actual fossil evidence associated with these assemblages is scant and fragmentary, and recent work has questioned the attribution of the Chatelperronian to Neanderthals on the basis of taphonomic mixing and lithic analysis. Here we reanalyse the deciduous molars from the Grotta del Cavallo (southern Italy), associated with the Uluzzian and originally classified as Neanderthal. Using two independent morphometric methods based on microtomographic data, we show that the Cavallo specimens can be attributed to anatomically modern humans. The secure context of the teeth provides crucial evidence that the makers of the Uluzzian technocomplex were therefore not Neanderthals. In addition, new chronometric data for the Uluzzian layers of Grotta del Cavallo obtained from associated shell beads and included within a Bayesian age model show that the teeth must date to ~45,000-43,000 calendar years before present. The Cavallo human remains are therefore the oldest known European anatomically modern humans, confirming a rapid dispersal of modern humans across the continent before the Aurignacian and the disappearance of Neanderthals.     

Deleterious mutations and the evolution of sexual reproduction

The origin and maintenance of sexual reproduction continues to be an important problem in evolutionary biology. If the deleterious mutation rate per genome per generation is greater than 1, then the greater efficiency of selection against these mutations in sexual populations may be responsible for the evolution of sex and related phenomena. In modern human populations detrimental mutations with small individual effects are probably accumulating faster than they are being eliminated by selection.     

Inference of human population history from individual whole-genome sequences

The history of human population size is important for understanding human evolution. Various studies have found evidence for a founder event (bottleneck) in East Asian and European populations, associated with the human dispersal out-of-Africa event around 60 thousand years (kyr) ago. However, these studies have had to assume simplified demographic models with few parameters, and they do not provide a precise date for the start and stop times of the bottleneck. Here, with fewer assumptions on population size changes, we present a more detailed history of human population sizes between approximately ten thousand and a million years ago, using the pairwise sequentially Markovian coalescent model applied to the complete diploid genome sequences of a Chinese male (YH), a Korean male (SJK), three European individuals (J. C. Venter, NA12891 and NA12878 (ref. 9)) and two Yoruba males (NA18507 (ref. 10) and NA19239). We infer that European and Chinese populations had very similar population-size histories before 10-20?kyr ago. Both populations experienced a severe bottleneck 10-60?kyr ago, whereas African populations experienced a milder bottleneck from which they recovered earlier. All three populations have an elevated effective population size between 60 and 250?kyr ago, possibly due to population substructure. We also infer that the differentiation of genetically modern humans may have started as early as 100-120?kyr ago, but considerable genetic exchanges may still have occurred until 20-40?kyr ago.     

浅谈市政工程项目管理的现状及解决措施

我国市政工程的项目管理已走过了二十几年的历程,形成了具有现代管理意义的项目管理机制,但还存在很多问题和不足,特别是在近几年我国市场经济逐步完善的情况下,更需要不断创新,探索有中国特色的现代建设工程项目施工管理模式,以适应市场经济发展的需要。     

The star-formation history of the Universe from the stellar populations of nearby galaxies

The determination of the star-formation history of the Universe is a key goal of modern cosmology, as it is crucial to our understanding of how galactic structures form and evolve. Observations of young stars in distant galaxies at different times in the past have indicated that the stellar birthrate peaked some eight billion years ago before declining by a factor of around ten to its present value. Here we report an analysis of the 'fossil record' of the current stellar populations of 96,545 nearby galaxies, from which we obtained a complete star-formation history. Our results broadly support those derived from high-redshift galaxies. We find, however, that the peak of star formation was more recent--around five billion years ago. We also show that the bigger the stellar mass of the galaxy, the earlier the stars were formed, which indicates that high- and low-mass galaxies have very different histories.     

Molecular biological analysis of remains from Jiangjungou Cemetery in Inner Mongolia

The 364-bp nucleotide sequence in hypervariable region I (HVRI) of mitochondrial DNA is successfully amplified from 9 out of 11 individuals of an ancient population buried in the Jiangjungou Cemetery in Inner Mongolia dated back to the Warring States Period in China. Nine fragments with different variations are obtained. A phylogenetic tree and a multidimensional scaling (MDS) plot are constructed using mtDNA sequences from the ancient population and several modern Asian populations. The results show that ancient population shares a closer genetic relationship with East Asian populations than with North and Central Asian populations. The genetic and historical evidence raise the possibility that the population might be the immigrants from Zhongyuan area, sent by the King Wuling of Zhao State to guard the nation against the attack from Huns.     

现代新儒学发展的轨迹

对20年来有关现代新儒学之研究提出省思。个人接纳主流意见所提供的一份15人名单，并综合各家意见提出了“三代四群”的架构。把这一架构与现代新儒家思潮的四波发展配合起来，当可把握到这一思潮的脉动。     

PCR amplification of the Irish potato famine pathogen from historic specimens

Late blight, caused by the oomycete plant pathogen Phytophthora infestans, is a devastating disease of potato and was responsible for epidemics that led to the Irish potato famine in 1845 (refs 1,2,3,4,5). Before the 1980s, worldwide populations of P. infestans were dominated by a single clonal lineage, the US-1 genotype or Ib mitochondrial DNA (mtDNA) haplotype, and sexual reproduction was not documented outside Mexico, the centre of diversity of the pathogen. Here we describe the amplification and sequencing of 100-base-pair fragments of DNA from the internal transcribed spacer region 2 from 28 historic herbarium samples including Irish and British samples collected between 1845 and 1847, confirming the identity of the pathogen. We amplified a variable region of mtDNA that is present in modern Ib haplotypes of P. infestans, but absent in the other known modern haplotypes (Ia, IIa and IIb). Lesions in samples tested were not caused by the Ib haplotype of P. infestans, and so theories that assume that the Ib haplotype is the ancestral strain need to be re-evaluated. Our data emphasize the importance of using historic specimens when making inferences about historic populations.     

外诗汉译中的诗学对话与融合意识——以余光中为个案的研究

外诗汉译的研究常常需要与现代汉诗的研究结合在一起。回顾现代汉诗的百年演变,有两条线索值得我们关注:一是现代汉诗在中外诗学的对话与融合中发展;二是现代汉诗在外诗汉译的影响中发展。如果在外诗汉译中就有意识地展开中外诗学的对话与融合,现代汉诗的发展将不仅从中直接受益,而且能少受其负面影响。余光中的英诗汉译实践充分证明了这一点,即他的译诗实践浸透着中英诗学的对话与融合意识,这不仅决定了他的译诗品质,也直接助益了他的诗歌创作。     

Radiocarbon dating of interstratified Neanderthal and early modern human occupations at the Chatelperronian type-site

The question of the coexistence and potential interaction between the last Neanderthal and the earliest intrusive populations of anatomically modern humans in Europe has recently emerged as a topic of lively debate in the archaeological and anthropological literature. Here we report the results of radiocarbon accelerator dating for what has been reported as an interstratified sequence of late Neanderthal and early anatomically modern occupations at the French type-site of the Chatelperronian, the Grotte des Fées de Chatelperron, in east-central France. The radiocarbon measurements seem to provide the earliest secure dates for the presence of Aurignacian technology--and from this, we infer the presence of anatomically modern human populations--in France.     

Parasites and climate synchronize red grouse populations

There is circumstantial evidence that correlated climatic conditions can drive animal populations into synchronous fluctuations in abundance. However, it is unclear whether climate directly affects the survival and fecundity of individuals, or indirectly, by influencing food and natural enemies. Here we propose that climate affects trophic interactions and could be an important mechanism for synchronizing spatially distributed populations. We show that in specific years the size of red grouse populations in northern England either increases or decreases in synchrony. In these years, widespread and correlated climatic conditions during May and July affect populations regionally and influence the density-dependent transmission of the gastrointestinal nematode Trichostrongylus tenuis, a parasite that reduces grouse fecundity. This in turn forces grouse populations into synchrony. We conclude that specific climatic events may lead to outbreaks of infectious diseases or pests that may cause dramatic, synchronized changes in the abundance of their hosts.     

两千年前人与当代人上颌第二前磨牙牙釉质厚度的测量观察

通过对两千年前人与当代人上颌第二前磨牙牙釉质厚度的比较,探寻牙釉质厚度的变化及牙齿不同部位牙釉质厚度的差异.运用Micro-CT对两千年前人及当代人各10颗上颌第二前磨牙进行扫描,三维重建后测量不同部位牙釉质的厚度.结果上颌第二前磨牙牙釉质厚度,当代人颊尖、舌尖、颊尖区咬合侧、舌尖区咬合侧均大于两千年前人,P<0.05;中央窝处牙釉质厚度,当代人明显大于两千年前人,P<0.01;上颌第二前磨牙不同部位牙釉质厚度比较,舌尖区牙釉质厚度大于颊尖区牙釉质厚度,P<0.01;近中邻面牙釉质厚度大于远中邻面牙釉质厚度,P<0.05;舌面牙釉质厚度大于颊面牙釉质厚度,P<0.05.两千年前人与当代人在牙釉质厚度分布上没有区别.说明牙釉质厚度可能呈现出不断增厚的趋势;此外,同一牙位功能尖区牙釉质厚度大于非功能尖区牙釉质厚度.     

中国企业制度转型中的思考

1999年，中华人民共和国迎来建国50周年纪念日，经过50年的努力，中国克服了重重困难，实现了由计划经济体制向市场经济体制的转换，取得了举世瞩目的成就，中国企业制度也在向现代企业制度转型过程中取得了重大突破，但应该看到，现代企业制度的构建是一项系统工程，要使中国企业真正达到这个目标，还需不断地努力。     

厦门市机动车保有量的预测方法

为了预测厦门市未来5年、15年的机动车保有量,以厦门市历年机动车保有量为研究对象,选取地区GDP、财政总收入、人均可支配收入、燃料零售价格指数、常住人口、公路通车里程等6个影响较大的数据指标.采用传统的非线性回归方法,主成份分析与Logistic模型相结合的方法,综合考虑两种预测方法及其结果,预测厦门市2020年、2030年的机动车保有量分别约为220万辆、530万辆.     

武汉纺织大学百年发展史研究——兼论张之洞对武汉纺织教育的历史贡献

张之洞督鄂十余年,不仅在湖北武汉建立起包括冶金、矿业、军工、纺织等行业门类较为齐全的近代工业体系,而且建构了近代工业教育体系.光绪二十四年(1898)张公亲自创办湖北工艺学堂,将农桑、丝绸织造教育纳入工艺学堂教育之中,由此揭开了近代纺织教育的历史新篇章.他在开创近代纺织教育的过程中,形成了独具特色的教育思想并付诸实践.112年来武汉纺织教育薪火相传、一脉相承,武汉纺织大学作为武汉纺织教育的惟一传承者,其教育史、校史应遵循唯物史观得出具有112年悠久办学历史的科学结论,她与华中农业大学同时开办,与武汉科技大学同根同源,是具有百年历史渊源的一所国立纺织大学.     

现代电化教育技术下的旅游英语教学模式

现代电化教育技术和互联网的发展,使建构主义教学理论所倡导的以教师为主导,学生为主体的教学理念能更好地在外语教学实践中加以贯彻实施。本文就三年来旅游英语课程教学改革进行了描述与分析,表明如果能充分利用现代电化教育技术和互联网的便利,就能够在外语教学活动中有效实施建构主义教学理论所倡导的教学模式,从而能充分调动学生外语学习的积极主动性,培养学生的创新能力,并能极大提高外语教学效率。     

分形集与分数维

本文简要介绍最新数学分支——《分形几何》的研究对象、方法、应用以及研究动态.