关系模式规范化的几个算法

本文在不计算函数依赖集闭包的情况下,给出了求关系模式关键字、BCNF判定和分解、寻找BCNF分解中丢失的函数依赖等几个算法。     

Combining multivariate analysis and geochemical approaches for assessing heavy metal level in sediments from Sudanese harbors along the Red Sea coast

Multivariate statistical analysis and geochemical approaches were exploited for the assessment of the level of some heavy metals (Mn, Fe, Ni, Cu, Zn and Pb) in sediments from Sudanese harbors along the Red Sea coast. Principal component analysis, as a multivariate statistical analysis approach, was applied to identify contribution sources by heavy metals in sediments. While a single source (crustal) was recorded in the bulk sediments and coarse sediment grains (grain-size 1000-500 µm), two sources (crustal and anthropogenic) were recorded in fine sediment grains (grain-size < 500 µm). Furthermore, enrichment factor (EF), as a geochemical approach, appointed polluted sites by heavy metals in the study area. Based upon a previous study addressed the interpretation of EF values, minor to moderate anthropogenic enrichment were recorded in sediments from some sites in the study area. The main anthropogenic activities that believed to be the major sources of pollution by heavy metals in the study area are discharges from oil refinery, industry, shipping activity and domestic waste. Hierarchical cluster analysis (HCA), as another multivariate statistical analysis approach, was applied for the concentrations of heavy metals in bulk sediments to group sediments according to their mineralogical composition. The output of HCA is that sediments from the Port-Sudan harbor can be divided mainly into three areas — east, west and south. For the Sawakin harbor, no apparent trend for the spatial distribution of heavy metals in sediments was recorded.     

Genome-wide predicting disease-related protein complexes by walking on the heterogeneous network based on data integration and laplacian normalization

BackgroundAssociating protein complexes to human inherited diseases is critical for better understanding of biological processes and functional mechanisms of the disease. Many protein complexes have been identified and functionally annotated by computational and purification methods so far, however, the particular roles they were playing in causing disease have not yet been well determined.ResultsIn this study, we present a novel method to identify associations between protein complexes and diseases. First, we construct a disease-protein heterogeneous network based on data integration and laplacian normalization. Second, we apply a random walk with restart on heterogeneous network (RWRH) algorithm on this network to quantify the strength of the association between proteins and the query disease. Third, we sum over the scores of member proteins to obtain a summary score for each candidate protein complex, and then rank all candidate protein complexes according to their scores. With a series of leave-one-out cross-validation experiments, we found that our method not only possesses high performance but also demonstrates robustness regarding the parameters and the network structure. We test our approach with breast cancer and select top 20 highly ranked protein complexes, 17 of the selected protein complexes are evidenced to be connected with breast cancer.ConclusionsOur proposed method is effective in identifying disease-related protein complexes based on data integration and laplacian normalization.     

谈谈物理实验课的教学管理

为了提高物理实验课的教学质量．有必要加强实验教学的规范化、制度化建设。我们对此作了初步的实践和探索。     

Statistical properties of two-dimensional periodic Lorentz gas with infinite horizon

We study the asymptotic statistical behavior of the 2-dimensional periodic Lorentz gas with an infinite horizon. We consider a particle moving freely in the plane with elastic reflections from a periodic set of fixed convex scatterers. We assume that the initial position of the particle in the phase space is random with uniform distribution with respect to the Liouville measure of the periodic problem. We are interested in the asymptotic statistical behavior of the particle displacement in the plane as the timet goes to infinity. We assume that the particle horizon is infinite, which means that the length of free motion of the particle is unbounded. Then we show that under some natural assumptions on the free motion vector autocorrelation function, the limit distribution of the particle displacement in the plane is Gaussian, but the normalization factor is (t logt)^1/2 and nott ^1/2 as in the classical case. We find the covariance matrix of the limit distribution.     

基于光谱相似度的恒星大气参数自动测量方法

采用模板匹配方法进行恒星光谱的自动处理时,不需要计算光谱的线指数,而采取对全谱匹配的方法尽可能多的保存有用的信息,可得到比较理想的结果。提出一种基于光谱相似度的恒星大气参数自动测量的方法。首先对恒星光谱进行连续谱归一化,然后通过计算待测光谱和模板光谱之间的相似性来进行模板匹配,从而得到相对准确的恒星大气参数。通过ELODIE实测光谱数据和NGS理论模板库之间的实验表明,本方法可有效进行恒星大气参数的自动测量,并能得到理想的结果。     

基于距离度量的LAMOST光谱中连续谱异常的自动检测

连续谱异常是指恒星光谱在获得和处理过程中由于星际消光和流量定标等原因造成连续谱严重偏离甚至中断的现象,这对光谱的谱线提取以及其他一些后续处理工作带来负面影响。提出了一种基于距离度量的连续谱异常光谱的自动检测方法,相比传统人眼检查在保证正确率的情况下大大地提高了工作效率。该方法首先通过光谱的lick线指数来确定待测光谱的恒星类型,同时对待测光谱进行归一化处理;然后分别提取待测光谱和对应类型模板光谱的连续谱;最后进行连续谱模板匹配,在每个波长点计算待测光谱和其模板光谱的流量差值,分析流量差值的分布,检验有多少差值点分布在在均值(β)附近的±α个标准差(δ)的范围内,进而可确定是否有连续谱异常。实验表明提出方法的可以快速有效的识别出连续谱异常的恒星光谱。     

Tumor-Exocytosed Exosome/Aggregation-Induced Emission Luminogen Hybrid Nanovesicles Facilitate Efficient Tumor Penetration and Photodynamic Therapy

The development of novel photosensitizing agents with aggregation-induced emission (AIE) properties has fueled significant advances in the field of photodynamic therapy (PDT). An electroporation method was used to prepare tumor-exocytosed exosome/AIE luminogen (AIEgen) hybrid nanovesicles (DES) that could facilitate efficient tumor penetration. Dexamethasone was then used to normalize vascular function within the tumor microenvironment (TME) to reduce local hypoxia, thereby significantly enhancing the PDT efficacy of DES nanovesicles, and allowing them to effectively inhibit tumor growth. The hybridization of AIEgen and biological tumor-exocytosed exosomes was achieved for the first time, and combined with PDT approaches by normalizing the intratumoral vasculature as a means of reducing local tissue hypoxia. This work highlights a new approach to the design of AIEgen-based PDT systems and underscores the potential clinical value of AIEgens.     

激光烧蚀-等离子体质谱结合归一定量方法原位线扫描检测石榴石多种元素

探讨了基体归一定量技术在实际应用中存在的问题.外标结合内标归一校正法避免了内标法中需要采用其它微区技术测定内标含量的繁琐步骤,可方便地用于具有环带结构等难以找到均匀分布的内标元素的地质样品的元素空间分布测定,解决了在采用直接外标法进行基体归一时,不能同时采用多外标进行校正的缺陷.激光线扫取样的最大优势是快速、省时.采用线扫的激光取样方式,结合归一定量技术,对具有环带结构的天然石榴石样品中的45种元素进行了分析测定,并与传统的激光打坑结果作对比,结果令人满意.     

气体色谱分析的多图谱归一定量法和气体组分的相对校正因子

本文报道一种扩展的气相色谱归一化定量分析方法，使两台或两台以上色谱仪对同一样品的诸多组分所完成的多张色谱力痛应用归一定量法进行计算，从而在进行多组分测定（尤其是气体样品的分析）时大大减少工作量，本方法的关键是样品中某一组分在多张图谱中均有分离很好的峰。