云南僰人源流的父系和母系遗传研究

对云南僰人32份男性DNA样本进行Y染色体单倍型以及mitochondrial DNA (mtDNA)单倍型分析,结果发现云南僰人的父系和母系遗传组分都表现出典型的南方人群的遗传特征.由僰人的数据结合已经发表的东亚人群的Y染色体和mtDNA单倍型(haplotype)数据进行Multidimensional Scaling(MDS)分析,结果表明,在MDS分布图中僰人群体的Y染色体单倍型和mtDNA单倍型都与南方人群聚在一起.这一结果支持僰人的遗传族源为东亚南方人群后裔,与考古学的推论相一致.结合历史和考古学证据来探讨僰人的起源和史前迁移,为揭开"僰人悬棺"这种独特的考古文化的起源和史前传播提供遗传学的研究证据.

Genetic diversity of plankton community as depicted by PCR-DGGE fingerprinting and its relation to morphological composition and environmental factors in lake donghu

To collect information about the genetic diversity of the plankton community and to study how plankton respond to environmental conditions, plankton samples were collected from five stations representing different trophic levels in a shallow, eutrophic lake (Lake Donghu), and investigated by PCR-DGGE fingerprinting. A total of 100 bands (61 of 16S rDNA bands and 39 of 18S rDNA bands) were detected. The DGGE bands unique to any single station accounted for 38% of the total bands, whereas common bands detected at all five stations accounted for only 11%. Using UPGMA clustering and MDS ordination of DGGE fingerprints, stations I and II were found to initially group together into one cluster, which was later joined by station V. Stations III and IV were isolated into two separate groups of one station each. Some differences in grouping relationships were found when analysis was completed on the basis of chemical characteristics and morphological composition, with zooplankton composition showing the greatest variability. However, the most similar stations (I and II) were always initially grouped into one cluster. Moreover, stations that exhibited the same or similar trophic level (stations III and IV), but different concentrations of heavy metals, were further differentiated by the DGGE method. Results of the present study indicated that PCR-DGGE fingerprinting was more sensitive than the traditional methods, as other studies suggested. Additionally, PCR-DGGE appears to be more appropriate for diversity characterization of the plankton community, as it is more canonical, systematic, and effective. Most importantly, fingerprinting results are more convenient for the comparative analyses between different studies. Therefore, the use of the described fingerprinting analysis may provide an operable and sensitive biomonitoring approach to identify critical, and potentially negative, stress within an aquatic ecosystem.

Investigation of GaSb epilayer grown on vicinal GaAs(001) substrate by high resolution x-ray diffraction

GaSb epilayers grown on GaAs(001) vicinal substrate misoriented towards (111) plane were studied using high-resolution x-ray diffraction (HRXRD). The results show that GaSb epilayers exhibit positive crystallographic tilt and the distribution of 60 degrees misfit dislocations (MDs) is imbalanced. The vicinal substrate also leads to the anisotropy of the mosaic structure, i.e. the lateral coherent lengths in [1 (1) over bar0] directions are larger than those in [110] directions. Furthermore, the full-width at half maximum (FWHM) of the off-axis peaks varies with the inclination angle, which is a result of different dislocation densities in the {111} glide planes.

Influence of dislocation stress field on distribution of quantum dots

InAs quantum dots (QDs) were grown on In0.15Ga0.85As strained layers by molecular beam epitaxy on GaAs (0 0 1) substrates. Atomic force microscopy and transmission electron microscopy study have indicated that In0.15Ga0.85As ridges and InAs QDs formed at the inclined upside of interface misfit dislocations (MDs). By testifying the MDs are mixed 60 degrees dislocations and calculating the surface stress over them when they are 12-180 nm below the surface, we found the QDs prefer nucleating on the side with tensile stress of the MDs and this explained why the ordering of QDs is weak when the InGaAs layer is relatively thick. (c) 2006 Elsevier B.V. All rights reserved.

A power-saving scheme for IEEE 802.11 Ad hoc networks

In the Wireless Local Area Networks (WLANs), the terminals are often powered by battery, so the power-saving performance of the wireless network card is a very important issue. For IEEE 802.11 Ad hoc networks, a power-saving scheme is presented in Medium Access Control (MAC) layer to reduce the power consumption by allowing the nodes enter into the sleep mode, but the scheme is based on Time-Drive Scheme (TDS) whose power-saving efficiency becomes lower and lower with the network load increasing. This paper presented a novel energy-saving mechanism, called as Hybrid-Drive Scheme (HDS), which introduces into a Message.-Drive Scheme (MDS) and combines MDS with the conventional TDS. The MDS, could obtain high efficiency when the load is heavy; meanwhile the TDS has high efficiency when the network load is small. The analysis shows that the proposed HDS could obtain high energy-efficiency whether the network load is light or heavy and have higher energy-saving efficiency than conventional scheme in the IEEE 802.11 standard.

桃树茎直径微变化与土壤水势及气象因子的关系

通过对充分供水和逐步干旱处理的盆栽"仕女红"桃树茎直径微变化动态的观测,分析了茎直径日最大收缩量(MDS)、日增长量(DI)和日最大值恢复时间(RT)对水分状况和气象因子的响应,并对适宜灌溉控制指标进行了探讨。结果表明:随土壤水势降低,桃树茎直径MDS和RT呈增大趋势,DI呈下降趋势并由正值变为负值;气象因子对桃树茎直径变化影响显著,太阳辐射(Rn)和空气相对湿度(RH)对MDS影响最强烈,连续降雨对DI和RT影响显著。DI受土壤水势影响产生变化的趋势明显并受气象因子影响较小,是最理想的灌溉控制指标,可将DI=0作为灌溉控制临界值;MDS受气象因子影响强烈,变异性较大,且需要充分灌溉条件下的MDS作为参考,RT与土壤水势的相关性不高,因此均不适合单独作为灌溉控制指标。

桃树茎直径变化及其与气象因子关系

用线性差分径向变化仪连续监测充分灌溉条件下的仕女红桃树茎直径变化,结合同步观测的气象因子数据,分析2007年3月中旬～10月下旬的仕女红桃树茎直径变化规律,为基于果树直径变化的灌溉管理提供基础依据。结果表明:仕女红桃树茎直径具有很好的时间变化规律,日变化曲线呈均匀"U"型,日最大值出现在黎明前后,日最小值出现在下午4时左右;季节变化方面,MDS呈低—高—低变化规律,从萌芽—开花期到果实成熟期的不同生长阶段,MDS平均值依次为87μm、200.84μm、253.75μm、171.67μm、138.67μm和94.34μm,坐果—展叶期和第一次果实膨大期MDS值居全生育期最高,需水量最大。桃树直径生长呈慢—快—慢变化规律,3月中下旬,开始生长,平均日生长量从12.68μm逐渐增加大36.84μm,7月24日～8月23日之间生长最快,平均日生长量达73.67μm,然后迅速下降,到生长末期平均日生长量仅为7.36μm。3～5月和7～9月可分别采用DI和MDS作为灌溉控制指标。茎直径变化与气象因子响应强烈,但不同生长阶段对茎直径变化产生主要影响的气象因子不同,对MDS产生主要影响的气象因子依次为:Rn、Tmax、Tma...

聚芳醚酮酮的高分辨像研究及亚稳结晶行为

聚芳醚酮酮是一种新型、高性能的工程热塑料。特别是具有对位苯连接的聚芳醚酮酮，存在着多晶型现象而备受关注。研究聚芳醚酮酮的结晶形态、各种晶型之间的相互转化及形成条件对聚芳醚酮酮的加工与应用有着至关重要的意义。本论文应用高分辨电子显微术（HRTEM），采用最小计量方法(MDS)及最佳感光法手段，克服了高分子材料不耐电子束辐照损伤及衬度较弱而难以拍摄高分辨像的困难，成功地拍摄了聚芳醚酮酮的晶格像及二维结构像。从分子水平上直接观察到了聚芳醚酮酮的晶胞在空间的二维投影及晶体缺陷。系统地研究了聚芳醚酮酮的结晶形态、稳态及亚稳态晶体的生成条件、结构特征及相互之间的转变，揭示了亚稳态晶体的尺寸诱导效应。从分子水平上提出了刚性链高分子点阵扭曲和位错的结晶生长机理，对高分子的结晶生长理论提出了新的观点。本论文对高性能的聚芳醚酮酮的加工与应用具有实际的指导意义，丰富了刚性链高分子的结晶生长理论。从。一氯代蔡稀溶液中制得了具有间位苯连接的聚芳醚酮酮晶体。通过其高分辨电子显微像的研究，直接观察到了组成晶体的点阵扭曲和位错，并揭示出由分子链的堆砌错误引起的点阵扭曲和位错是导致球晶晶片展现出连续的分叉并向着晶体的增长前沿逐渐变窄的直接原因，从分子水平上揭示了聚芳醚酮酮的结晶形态的特点。首次对存在于晶格中点阵的过渡进行了深层次的阐述，点阵过渡的形成是由于分子链堆砌在纵向方向不同的排布所引起的。首次成功发现并揭示出聚芳醚酮酮的球晶形态对结晶薄膜厚度的依赖性，随着结晶薄膜厚度的增加，其球晶形态呈现着从各自分开的单个纤维状片层，到只有几个纤维片层构成的初生态球晶，再到或多或少成熟一些的二维球晶，甚至到由于球晶晶片弯曲及分叉角度的降低，而出现具有伸直叶片形态的球晶这一变化过程，表明了晶体生长在空间尺度上的结晶受限行为。首次从聚芳醚酮酮的溶剂成膜结晶获得了亚稳态和稳态共存的晶体，并从亚稳态晶体较稳态晶体具有较小的结晶尺寸和较低的完善性及亚稳晶体向稳态晶体的转变，进一步揭示出亚稳晶体形成的尺寸诱导效应。通过亚稳晶体形成的冷结晶动力学分析和晶体的形态结构观察，揭示出亚稳晶体的形成是受热驱动控制的，其结晶速率随着结晶温度的提高而提高，而等温熔体结品却与之相反，揭示它们不同的温度依赖性，而且．其亚稳晶体具有较小的尺寸及动力学形成在于其具有较低的自由能阻。

长江口初级生产者物质输运及其与环境因子的关系

根据历史调查资料，运用聚类分析(Cluster)、多维标度分析(MDS)、典范对应分析(CCA)、冗余分析（RDA）等多元统计学方法，探讨了长江口群落结构变异、初级生产力水平变化的主要影响因素。结果表明，与八十年代相比，长江口生态与环境发生了显著改变，环境因子的改变直接影响长江口浮游植物的群落结构，并且各季节长江口浮游植物群落结构变异的驱动因素不同。季节间浮游植物群落结构变异的主要影响因子为温度、盐度、透明度、营养盐，其中温度始终是首要的影响因子，同一季节之间（春、秋季），浮游植物群落结构时空变异的主要影响因素为营养盐，不同的浮游植物类群对环境因子的响应机制不同。 运用细胞体积转换法计算浮游植物细胞碳含量，估计了长江口浮游植物群落对生源要素碳的贡献量，并分析了浮游植物群落碳含量与长江口理化环境因子的相关关系。结果显示，盐度、透明度、营养盐（氮和磷）是制约长江口浮游植 物碳含量分布的主要因子。 通过室内实验，探讨了长江口浮游植物绝对优势种—中肋骨条藻物质输运能力与环境因子的关系，建立了其生长速率、单位细胞叶绿素a的含量、颗粒有机碳的含量与环境因子之间的关系模型。分析结果显示温度、盐度、光照强度对中肋骨条藻的生长速率、细胞内叶绿素a和颗粒有机碳的含量均有显著的交互作用。

Community structure of macrobenthos in coastal water off Rushan, southern Shandong Peninsula, and the relationships with environmental factors

To understand the present actuality of the marine ecosystem in the southern coastal water region of the Shandong Peninsula and the impact of the global change and the human activities to the marine ecosystem of the region, the macrobenthic community structure was researched based on data from 26 sampling stations carried out on four seasonal cruises from December 2006 to November 2007. The data was analyzed using PRIMER 6.0 and SPSS 15.0 software packages. The results showed that 236 macrobenthic species in total were collected from the research region by the field works. Most of the species belong to Polychaeta (76 species), Mollusca (75) and Crustacea (60). Of which, 33 species were common species by the four cruises. The dominant species were different among the four seasons, however, the polychaete species Nephtys oligobranchia and Sternaspis scutata were always dominant in the four seasons. The abundances and biomasses of the macrobenthos from the research region were variable in tire four seasons. The results of CLUSTER and MDS analysis showed that the similarities of macrobenthic structures among the stations were low, most of the similarities were at about 40% of similarity values, only that of two stations were up to 60%. In accordance with the similarity values of the macrobenthic structures, the 26 stations were clustered as six groups at arbitrary similarity level of 30%. The ABC curve indicated that the marcofauna communities in the research region had riot been disturbed distinctly. The results of BIOENV and BVSTEP (Spearman) analysis implied that the concentrations of organic matter in bottom water and heavy metal copper in sediment, water depth and temperature of bottom were the most significant environmental factors to affect the macrobentic community.

Macrobenthic community structure in the Changjiang Estuary and its adjacent waters in summer

On the basis of data collected in the summer of 2006 from 27 sampling stations in the Changjiang Estuary and its adjacent waters, the ecological characteristics of macrobenthos and the relationship between the macrobenthos and the environmental factors were studied using hierarchical cluster and non-metric multidimensional scaling ( MDS). The biomass, abundance, Shannon - Wiener's and Margalef' s indices of the macrobenthos were presented. The results showed that a total of 253 maerobenthic species were found in the research region, and most. of them belong to mollusks and polychaetes. The dominant species were Cossurella dimorpha, Eocylichna cylindrella, Episiphon kiaochowwanense, Nassarius semiplicatus, Ocstergrenia variabilis and Sternaspis scutata. The average abundance of the macrobenthos was (313.15 +/- 233.4) ind. / m(2), and the average biomass was (15.2 +/- 11.2) g/ m(2). The distribution patterns of the abundance and biomass of the macrobenthos were similar. The abundance and biomass in the area close to the estuary were lower than those from the area more distant to the estuary; the central part of the research region had higher abundance and biomass than other parts of the research region. In accordance with the results, four macrobenthic communities with distinct spatial differences were identified. The low abundance and biomass in the area close to the estuary should be caused by the high sedimentation rate. The statistical analysis indicated that the depth is the most important factor affecting the distribution of macrobenthos.