基于熵理论的病例父母亲对照研究来精细定位

原始的连锁不平衡熵指数通过比较群体样本中标记熵和条件熵来定位疾病位点或数量性状位点．它可能受群体混杂的影响．而利用病例父母亲对照研究或其他的家系研究可以避免群体混杂的影响．本文拓展了连锁不平衡熵指数到病例父母亲数据,将没有传递给受累子代的父母亲的基因型视为对照样本．随机模拟的结果表明连锁不平衡熵指数适用家系研究．     

Visualizing number sequences: Secondary preservice mathematics teachers’ constructions of figurate numbers using magnetic color cubes

This study is about preservice secondary mathematics teachers’ visualization of summation formulas modeled by magnetic color cubes representations. The theoretical framework for this research draws from studies on quantitative reasoning (Smith and Thompson, 2008, Thompson, 1995) and quantitative transformations (Schwartz, 1988). Data consist of videotaped qualitative interviews during which preservice mathematics teachers were asked to construct growing rectangles representing summation formulas. Data analysis is based on analytic induction and constant comparison methodology. Preservice teachers provided a diversity of additive and multiplicative visualizations. Results indicate that quantitative reasoning and mapping structures are fundamental constructs in establishing additive and multiplicative visualizations, hence constructing summation formulas meaningfully. Preservice teachers often had difficulties in explaining the relationships between the same-valued linear and areal quantities. They also established the rectangle condition as the essence of multiplicative visualization.     

Long-term trend in aerosol optical depth from 1980 to 2001 in north China

Using the Total Ozone Mapping Spectrometer （TOMS） monthly aerosol optical depth （AOD） at 500 nm data from 1980 to 2001 in north China, the spatial and temporal variations of AOD were examined. Seasonal AODs in Taklimakan Desert were 0.69 and 0.44 in spring and summer, respectively, which were mainly due to frequent occurrences of dust events in this region. Dust activities in spring also led to high aerosol loading in Gobi Desert and in northeast China where spring AODs were 0.33 and 0.29, respectively. Heavily impacted by events such as volcano eruption, forest fires and extraordinary dust storms, AODs showed large inter-annual variations. A decreasing tendency in AOD was observed in north China during 1980-1991, though a reverse tendency was revealed during 1997-2001, especially for spring AOD in northeast China. Further study is required to figure out how much human activities have contributed to the AOD tendency in north China.     

Exact calculation of the flow of a staggered tandem cascade with moving second blade row

Summary  The plane flow around a tandem cascade of flat plates is calculated by means of conformal mapping. The blades of the two rows are perpendicular to each other. The first row is stationary, the second row moves with constant velocity. The conformal mapping will be constructed by a “mapping flow”. The blades of one row are stream lines and those of the other row are potential lines of the flow. By conformal mapping, the physical flow around the tandem cascade of the physical ζ-plane is converted into a flow between infinitely long straight walls in the z-plane, each wall corresponding to one of the blades. The conditions far upstream and far downstream of the cascade are represented by source-vortices. In the z-plane, the boundary conditions may be easily fulfilled by reflection and repetition of the source-vortices, and the flow may be calculated by well-known methods. The physical flow searched for is then obtained by inverse mapping. Received 24 July 2000; accepted for publication 6 December 2000     

Attenuated Total Reflection-Fourier transform infrared microspectroscopic mapping for the characterisation of paint cross-sections

Paint cross-sections have been analysed using the attenuated total reflection technique combined with FTIR mapping microspectroscopy in order to characterise the nature of the compounds present and map their localisation in the stratigraphy. The study reveals the possibilities offered by micro-ATR devices for obtaining informations about the organic substances employed in painting techniques and in particular their distribution in the different layers, showing a real improvement over traditional analytical investigations in use for the detection of organic substances. Limitations, such as the contamination of the embedding resin and the typical spectral resolution (20 μm) are presented and alternative methods were proposed to obtain better results. In particular, the use of an infrared transparent salt (KBr) as embedding material for the cross-sections is evaluated and seems to be very promising. Furthermore, ATR mapping represent a useful non-destructive analytical technique complementary to others molecular and elemental analyses to be performed afterwards such as SEM-EDX.     

N-Centralizing Mappings in Semiprime Rings

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半广义连续映射

这篇文章, 我们定义半广义连续映射, 研究它的一些性质, 给出它的等价刻画.     

Affine Configurations and Pure Braids

We show that the fundamental group of ordered affine-equivalent configurations with at least five points in the real plane is isomorphic to the pure braid group in as many strands, modulo its centre. In the case of four points, this fundamental group is free with 11 generators. This work was carried out at the Instituto de Matemáticas, UNAM and partially funded by the Sistema Nacional de Investigadores and a doctoral fellowship from CONACyT México.     

Computable Carathéodory Theory

The conformal Riemann mapping of the unit disk onto a simply-connected domain W is a central object of study in classical Complex Analysis. The first complete proof of the Riemann Mapping Theorem given by P. Koebe in 1912 is constructive, and theoretical aspects of computing the Riemann map have been extensively studied since. Carathéodory Theory describes the boundary extension of the Riemann map. In this paper we develop its constructive version with explicit complexity bounds.     

Cremona transformations and diffeomorphisms of surfaces

We show that the action of Cremona transformations on the real points of quadrics exhibits the full complexity of the diffeomorphisms of the sphere, the torus, and of all non-orientable surfaces. The main result says that if X is rational, then Aut(X), the group of algebraic automorphisms, is dense in Diff(X), the group of self-diffeomorphisms of X.