Genetic consequences of postglacial colonization by the endemic Yarkand hare （Lepus yarkandensis） of the arid Tarim Basin

Orogenesis of the Qinghai-Tibetan Plateau,which occurred in a stepwise manner,contributed to the extreme aridity of the Tarim Basin,resulting in vulnerable and unstable ecosystems.Quaternary climatic oscillations may have affected the ecosystems and,consequently,the distributions and genetic structuring of the Tarim Basin’s biota.We used nucleotide sequence data from 2 mitochondrial (mt) DNA genes (Cyt b and the D-loop) to test hypotheses associated with the matrilineal and demographical histories of the Tarim Basin’s endemic Yarkand hare (Lepus yarkandensis).Range-wide sampling involving 20 populations and 224 individuals detected 126 haplotypes that clustered into 5 major lineages in both the phylogenetic tree and median-joining network.Populations from the northern and eastern Tarim Basin shared a similar history,as did those from the western and southern regions.Demographical analysis and genetic diversity estimations suggested that the western and southern regions might have served as glacial refugia for the Yarkand hare during Quaternary climatic oscillations.The distribution of the Yarkand hare,especially in the northern and eastern parts,probably represented 3 postglacial colonization events,dated to 0.21,0.090 and 0.054 MYA,which corresponded to known interglacial periods.Given the relatively complete geographic isolation between the eastern and southern populations,the Yarkand hare likely dispersed during postglacial periods from the southwest to the north,and then onward to the east.The absence of water likely forced the species into refugia,and this differed from other Pleistocene biogeographical drivers.The demographical and historical patterns have important implications for conservation.     

一元回归在射表符合系数曲线制作中的应用

针对现有射表符合系数曲线绘制过程中存在的不足，运用一元回归方法对其进行改进，并验证了把该方法用于制作射表符合系数曲线时，可以提高试验数据处理效率以及试验数据的准确度．     

Bayes逐步判别法在邢台煤矿突水水源判别中的应用

快速有效地判别突水水源是矿井安全生产的重要保障。文章以邢台煤矿为研究对象,选取各含水层多项水质指标,应用Bayes逐步判别法建立矿井突水水源快速判别模型。结果表明:Bayes逐步判别模型以其计算过程简单、模型结构稳定而优于其它模型,既提高判别准确率又提高判别速度,实现对突水水源快速有效判别,为防治水工作提供有力依据。     

地基土对桥梁索塔抗震设计影响的研究与实践(之二)

以火箭式激振器为震源对高大结构物(即云南景洪澜沧江大桥主塔)进行了现场动力测试和分析,利用实测结构体系的动力特性,取得了场地土边界元参数,在考虑了土与结构相互作用的基础上,为选取全桥的抗震设计参数提供合理依据.     

Type-2 copper-containing enzymes

Type-2 Cu sites are found in all the major branches of life and are often involved in the catalysis of oxygen species. Four type-2 Cu protein families are selected as model systems for review: amine oxidases, Cu monooxygenases, nitrite reductase/multicopper oxidase, and CuZn superoxide dismutase. For each model protein, the availability of multiple crystal structures and detailed enzymological studies provides a detailed molecular view of the type-2 Cu site and delineation of the mechanistic role of the Cu in biological function. Comparison of these model proteins leads to the identification of common properties of the Cu sites and insight into the evolution of the trinuclear active site found in multicopper oxidases. Received 6 July 2007; accepted 18 July 2007     

企业参考资源模型的建立

提出参考资源模型结构,并给出其构造方法,研究其在建模导出过程中的支持作用.企业参考资源模型是一个资源的参考目录,在建立特定企业资源模型时,可以直接从参考资源模型中选取所需资源.参考资源模型的建立支持资源重组,缩短建模时间,从而加速建模的进程.     

Pentaploidy in hybrid salamanders demonstrates enhanced tolerance of multiple chromosome sets

Summary Breeding populations of unisexual hybrid salamanders (genusAmbystoma) are dominated by allotriploid (3n) and allotetraploid (4n) forms, however, sexually mature allopentaploids (5n) may also occur. These are the first known naturally-occurring pentaploid vertebrates, and their genesis differs from that of previously studied autopentaploid urodeles induced or observed in the laboratory. The latter always suffered severely deleterious effects in development, and could not attain sexual maturity.     

Nest site selection in raptor communities of the eastern Great Basin desert

Measures of niche breadth and overlap were used to compare nest site selection in a community of 10 raptor species and the Raven nesting in the eastern Great Basin Desert. Three variables were examined: nest site type, elevation, and exposure. Results suggest a division of component raptor species into relatively abundant core species that show wide niche breadths and uncommon fringe species with narrow niche breadths. Differences in use of each resource are most pronounced along elevation gradient in which three guilds are evident that correspond to raptor species groupings that nest at higher, middle, and lower elevations. Each guild is comprised of a mix of core and fringe species. Raptor species with highest overlap along one or more nest site variables examined are separated by differences in activity patterns.     

Raptors of the Uinta National Forest, Utah

The past and present use of the Uinta National Forest by birds of prey was determined from historical records and surveys conducted during 1973, 1974, and 1975. Data describing the history, present status, and physical characteristics of each nest site were collected, along with the type and intensivity of human activity within a half - mile radius of the nest. In addition, limited data on fall migration of raptors along the Wasatch Front and the food habits of Golden Eagles are presented. Management guidelines, based on the results of this study, are proposed.