A landscape pattern analysis method based on boundaries and nodes: A case study in upper Minjiang River, China

Traditionally,patch-based analysis at the landscape scale fragmentation has been used in the study of landscape ecology while the study of boundary and node has not been considered as much detail until recently.This study investigated the possibility of applying boundary-and node-based methods in landscape pattern analysis to the upper reaches of the Minjiang River in the southwestern China.Boundary-based and node-based landscape indices were selected to be used in analyzing changes in landscape patterns,and the results were compared with analysis using traditional pattern indices.We compared the responses of patch-area-based,boundary-length-based and node-number-based indices,and concluded that boundary-based and node-based indices are more sensitive to disturbance than patch-based indices with various patterns,and node-based indices are even more sensitive than boundary-based ones.Thus,the results suggest that boundary-based and node-based pattern analysis methods provide helpful supplementary information to traditional patch-based pattern analysis methods.The results about pattern dynamics of landscapes in the upper reaches of the Minjiang River based on boundaries and nodes showed that with human disturbance,the dominance of forest landscape was weakened by other landscape types; thus the landscape pattern of the study area became more homogeneous and the boundary network became more complex.These changes further augmented disturbance interfaces in the landscape and increased the possibilities of further landscape fragmentation.     

Adhesion mechanisms of Vibrio fluvialis to skin mucus of Epinephelus awoara

Vibrio fluvialis incubated in trypticase soy broth (TSB) showed stronger adhesion to the skin mucus of Epinephelus awoara than V. fluvialis grown on trypticase soy agar (TSA), and this bacterial adhesion was assessed in terms of saturation kinetics. Treating bacteria with antibody against O-antigens resulted in significantly reduced bacterial adhesion. In the early growth stage, the adhering bacteria numbers increased with incubation time, peaked at 24 h, and then dropped sharply. Prior heat treatment of the mucus at various temperatures resulted in different effects on bacterial adhesion. No remarkable effect on bacterial adhesion was detected after treating mucus with protease K and trypsin, whereas periodic acid treatment significantly enhanced bacterial adhesion. Extracts of V. fluvialis surface structures at high concentrations significantly inhibited bacterial adhesion, while relatively low concentrations enhanced adhesion. V. fluvialis had strong affinity for a high molecular weight mucus component. These results indicate that V. fluvialis adhered strongly to E. awoara mucus by specific adhesion and that this adhesion was influenced by many factors, including bacterial conditions, mucus, and the environment.     

Puzzling Origin of CEMP-r/s Stars: An Interpretation of Abundance and Enrichment of s- and r-Process Elements from Asymptotic Giant Branch Supernovae

CEMP-r/s stars at low metallicity are known as double-enhanced stars that show enhancements of both r-process and s-process elements. The chemical abundances of these very metal-poor stars provide us a lot of information for putting new restraints on models of neutron-capture processes. In this article, we put forward an accreted scenario in which the double enrichment of r-process and s-process elements is caused by a former intermediate-mass Asymptotic Giant Branch (AGB) companion in a detached binary system. As the AGB superwind is only present at the ultimate phase of AGB stars, there is thus a lot of potential that the degenerate-core mass of an intermediate-mass AGB star reaches the Chandrasekhar limit before the AGB superwind. In these circumstances, both s-process elements produced in the AGB shell and r-process elements synthesized in the subsequent explosion would be sprayed contemporaneously and accreted by its companion. Despite similarity to physical conditions of a core-collapse supernova, a major focus in this scenario is the degenerate C–O core surrounded by an envelope of a former intermediate-mass AGB donor that may collapse and explode. Due to the existence of an outer envelope, r-process nucleosynthesis is expected to occur. Hypothesizing the material-rich europium (Eu) accreted by the secondary via the wind from the supernova to be in proportion to the geometric fraction of the companion with respect to the exploding donor star, we find that the estimated yield of Eu (as representative of r-process elements) per AGB supernova event is about 1 × 10^?9 M _⊙ ～ 5 × 10^?9 M _⊙. Using the yields of Eu, the overabundance of r-process elements in CEMP-r/s stars can be accounted for. The calculated results show that the value of parameter f , standing for efficiency of wind pollution from the AGB supernova, will reach about 10⁴, which means that the enhanced factor is much larger than unity due to the impact of gravity of the donor and the result of the gravitational focusing effect of the companion.     

有益微生物改善养殖生态研究──Ⅰ.复合微生物分解有机底泥及对鱼类的促生长效应

应用以芽孢杆菌为主导菌的微生物复合制剂进行分解养鱼池有机污泥的试验,菌剂合活菌数为109个／g．用量为1.5～4．5mg·L－1。经一个月的试验,池底原有厚3～5cm的有机污泥被分解,并对鱼类有明显的促生长作用。说明应用以芽孢杆菌为主导菌的微生物复合制剂净化养殖池塘底质是一种有效的措施。     

儿茶酚胺类药物对草鱼鱼种生长激素分泌的影响

通过腹腔注射药物、尾静脉取血、放射免疫测定激素含量等方法研究L-多巴等几种药物对草鱼鱼种生长激素分泌的影响,发现腹腔注射L-多巴、阿朴吗啡可以显著提高草鱼鱼种血清生长激素水平,而腹腔注射多巴胺、去甲肾上腺素、肾上腺素和6-羟多巴则可明显降低草鱼鱼种血清生长激素水平。说明儿茶酚胺类参与了草鱼鱼种生长激素的分泌调节,L-多巴或其代谢物是通过中枢神经系统促进草鱼鱼种生长激素分泌的,而多巴胺、去甲肾上腺素和肾上腺素则是在脑垂体水平上抑制草鱼鱼种生长激素的分泌。     

中国东南陆缘的深部结构与动力学过程

对我国东南陆缘地区的人工地震测深、大地电磁测深、重磁测量、地热测量、地学大断面编制以及天然地震的层析成像等大量深部构造研究结果作综合分析。地热异常、地壳内存在低速层和高导层、强烈地震频繁发生等现象说明,这一地区是现代构造运动的活动区。中国东南陆缘的现今应力场主压应力方向为ＮＷＷ－ＳＥＥ,认为是菲律宾板块对欧亚板块的挤压,以及冲绳海槽的扩张等联合作用的结果。因此,这一地区地壳运动的驱动力是太平洋板块和菲律宾板块向欧亚板块推挤产生的。     

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Tectonic Movement and Global Climate Change

Glaciation between northern hemisphere and southern hemisphere were synchronous, the ice age occurred not in high but in low value of the eccentricity of the earth's orbit. Such facts went against the precession principle of the astronomical theory of ice age. The inhomogeneous distribution of climate consisted with the inhomogeneous distribution of ocean and continent. The north/south antisymmetry may be attributed to southward deviation of the thermal center and northward deviation of the mass center within the mantle demonstrated by seismic tomography. The core - mantle angular momentum makes rotational energy into thermal energy and mantle plumes erupt in the ocean bottom. The earth's deformation by tidal force makes the eruption of mantle plumes strong. They are the reason that glaciation between the Northern Hemisphere and Southern Hemisphere are synchronous and the ice age occurred in low value of the eccentricity of the earth' s orbit. The tectonic movement is playing a most important part in global climate change.     

二氧化氯控制欧洲鳗细菌性疾病

以二氧化氯作为一种新型的消毒剂和杀菌剂 ,以传统含氯制剂 (如漂白粉、二氯异氰尿酸钠、三氯异氰尿酸 )作为对照 ,比较其在治疗欧洲鳗细菌性疾病及改善养殖水质方面的显著特性 ,其作用活性与环境 (如 p H、温度、氨及有机物 )因子的关系。结果表明 ,二氧化氯 (Cl O2 )对爱德华氏菌、嗜水气单胞菌和柱状屈挠杆菌有很好的杀灭效果 ,能迅速治愈欧洲鳗的赤鳍病和肝肾病 ,且能有效改善养殖水体 ,水中生化需氧量比对照组下降 10 %～ 30 % ,化学耗氧量下降 5% ,溶氧量提高 8%～ 10 %。当二氧化氯体积分数为 8m L/m3时 ,其杀菌率均高达 90 %以上 ,为氯制剂的 1.8倍 ,且活性不受环境因子的影响