全球N-MORB和E-MORB分类方案对比

N-MORB与E-MORB是大洋中脊玄武岩常用的分类,二者地球动力学意义不同,备受学术界关注。对于N-MORB与E-MORB的分类识别标志,不同作者有不同的见解。MORB中可以根据Rb/Nd≤0.15、K/Ti≤0.11、(La/Sm)_N≤0.8、K_2O/TiO_20.09、ΔNb=1.74+lg(Nb/Y)-1.92lg(Zr/Y)0、(La/Sm)_N1、100K_2O/TiO_2≤13等7种指标来识别N-MORB,否则为E-MORB。究竟何种标志区分效果较好、比较适合大多数MORB的情况?学术界对此还较少有人讨论。为此,本文尝试利用大数据方法,采用全球全体扩张中心数据,对上述7种标志进行对比,发现(La/Sm)_N1的标志比较适合大多数MORB的情况。为此,我们将(La/Sm)_N1和(La/Sm)_N≥1的所有数据,选取La、Ce、Pr、Nd、Sm、Eu、Gd、Tb、Dy、Ho、Er、Tm、Yb、Lu、Ba、Cs、Hf、K、Nb、Pb、Rb、Sc、Sr、Ta、Th、Ti、Tl、U、V、Y、Zr等31个元素,利用两两元素对数比值进行投图,并计算85%置信度的置信椭圆交叠率,共得出36856个元素对组合,根据最小交叠率的原则,得出使用稀土元素La、Ce、Pr、Sm和其他高场强元素Nb、Zr、Hf、Y之间的比值关系判别效果较好。我们又利用以上得出的8种元素进行投图判定,发现以La为分子或以La/Hf、La/Zr元素比值做为区分标志可以得出更好的结果。因此建议考虑应用以上元素之间的相关关系共同判定N-MORB与E-MORB。     

尼罗罗非鱼(Oreochromis niloticus)不同月龄性状的主成分与判别分析

采用主成分与判别分析的方法,研究尼罗罗非鱼形态性状的增长规律,并判定其最佳生长季节体格与月龄的关系。选择2—5月龄尼罗罗非鱼各100尾,测量体长、头长、躯干长、体高、尾柄长、尾柄高、体宽和体重共8个性状,并对其进行主成分与判别分析。主成分分析结果表明:尼罗罗非鱼各月龄的体型特征参数间均有不同程度的正相关(P<0.05),体重与体长、体高的相关性最显著;不同月龄尼罗罗非鱼性状的主成分有所不同,主成分1:2—5月龄均相同为增重因子;主成分2:2—4月龄均为尾柄因子,而5月龄是躯干因子;主成分3:2月龄是头部因子,3—4月龄是躯干因子,5月龄是尾柄因子。通过建立判别式来判断错过最佳生长季节尼罗罗非鱼的体格与大小相符的月龄,判别结果表明,总的判别准确率为99.25%,其中2—4月龄尼罗罗非鱼的判别准确率为100%。     

日本囊对虾(Marsupenaeus japonicus)3个野生种群和1个养殖种群的形态差异与判别分析

采用3种多元分析方法,对3个野生种群和1个养殖种群的13个形态比例参数进行比较研究。聚类分析结果表明,广东湛江和海南临高的种群形态最接近,福建厦门种群的趋异程度最大。主成分分析构建了6个主成分,其贡献率分别为:第1主成分23.084%,第2主成分17.976%,第3主成分15.321%,第4主成分13.84%,第5主成分12.707%,第6主成分7.770%,累积贡献率为90.699%。逐步判别选入6个贡献率较大的性状进行判别分析,F检验结果显示,4个种群形态差异显著(P0.01);同时建立了4个种群的判别函数,其判别准确率P1、P2均为100%。综合判别率为100%。3种多元分析结果均认为,4个种群日本囊对虾在形态上已产生一定程度的差异,且集中表现在体重、头胸甲的性状上。     

肝脏肺吸虫病的CT诊断

作者认为肺吸虫病发生在肝脏系少见病例，以ＣＴ认识和诊断上有待进一步提高，特别与肝结核、肝脓肿、肝包虫囊肿等鉴别诊断，仍存在一定的困难。临床上肺吸虫病多见脑部，肺，及皮下组织，我院病理科近十余年在肝脏发现肺吸虫病也是仅有一例，上述疾病ＣＴ表现均可出现低密度坏死区，有规则环状增强，斑点状钙化灶，单房及改变及大小不等的结节。组织学上的改变，肝细胞混浊肿胀，液化，变性，坏死，钙化，所不同处寄生虫病的病理组     

An Approach for Classification of Groundwaters by Synchronous Fluorescence Spectroscopy and Discriminant Analysis

Monitoring and evaluation of groundwater quality in drinking water protectorates is of particular interest if the uncontrolled entry of pollutants, for example by infiltrating river water, cannot be excluded. A fluorescence spectroscopic method is presented as possible alternative to the conventional expensive hydrochemical investigations. This method uses the information yielded by synchronous fluorescence spectra. After a Fourier transformation of the original spectra and a following discriminant analysis, the samples can be classified in different groups corresponding to the different types of groundwater. The method was tested in the drinking water protectorate of a waterworks of a German metropolis (Halle, Sachsen-Anhalt). We found a prediction rate of about 90% in the investigated case.     

Geochemical reconstruction of late Holocene drainage and mixing in Kluane Lake,Yukon Territory

The level of Kluane Lake in southwest Yukon Territory, Canada, has fluctuated tens of metres during the late Holocene. Contributions of sediment from different watersheds in the basin over the past 5,000 years were inferred from the elemental geochemistry of Kluane Lake sediment cores. Elements associated with organic material and oxyhydroxides were used to reconstruct redox fluctuations in the hypolimnion of the lake. The data reveal complex relationships between climate and river discharge during the late Holocene. A period of influx of Duke River sediment coincides with a relatively warm climate around 1,300 years BP. Discharge of Slims River into Kluane Lake occurred when Kaskawulsh Glacier advanced to the present drainage divide separating flow to the Pacific Ocean via Kaskawulsh and Alsek rivers from flow to Bering Sea via tributaries of Yukon River. During periods when neither Duke nor Slims river discharged into Kluane Lake, the level of the lake was low and stable thermal stratification developed, with anoxic and eventually euxinic conditions in the hypolimnion.     

Application of statistical methods to study seasonal variation in the mine contaminants in soil and groundwater of Goa, India

 Soil and groundwater samples were collected during two seasons, premonsoon (April 1990) and postmonsoon (December 1990), and analyzed for major elements (Na, Mg, Al, Si, P, K, Ca, Ti, Mn and Fe), trace elements (Ni, Pb, Co, Cr and Zn) and water parameters (pH, conductivity, acidity, alkalinity, hardness, Cl and SO₄). All the data were subjected to linear discriminant analysis and partial correlation analysis in order to understand the seasonal variation in the data. It was observed from the Mahalanobis generalized distance that in both soil and groundwater samples there was a large difference in the concentration level of premonsoon and postmonsoon data. Linear discriminant functions were calculated to distinguish between premonsoon and postmonsoon samples. From the partial correlation coefficient analysis of soil samples, dominance of chemical weathering and precipitation of atmospheric fallout during monsoon were inferred. In the case of the water samples, high conductivity and high hardness in the postmonsoon samples as well as atmospheric fallout of Pb and Ni during the premonsoon period was suggested from partial correlation of water samples. Received: 19 September 1995 · Accepted: 12 December 1995     

应用贝叶斯最佳二次型判别函数识别含油气火成岩岩性

 各种火成岩在某些地质条件下有可能成为好的油气储层。近年来,已经陆续在渤海湾以及华北等地发现了经次生改造的侵入岩(煌斑岩、花岗岩)、喷出岩(玄武岩、安山岩)、火山碎屑岩(安山质角砾岩、凝灰岩)等较好的油气储层。因此,根据测井资料应用一种数学方法自动识别含油气火成岩岩性,对寻找有利的油气产层十分重要(欧阳健、王杰英,1988)。采用的识别方法是贝叶斯最佳二次型判别函数(中国科学院计算中心概率统计组编著,1979;肖义越,1982)。