判别分析方法在医学应用中的进展

本文对医学领域中判别分析方法的新进展做一综述,介绍了微阵列基因表达数据判别分析中偏最小二乘法降维、离散小波变换法降维、logitboost算法、随机森林、模糊核判别分析以及时间序列多元数据有序判别分析法、自身有变化规律数据的变系数logistic回归模型判别分析法的基本思想、算法和适用条件。     

Friction and heat transfer in drag-reducing surfactant solution flow through curved pipes and elbows

A study of drag-reducing flow in curved pipes was conducted. In contrast to earlier studies we show that if we use a modified definition of drag reduction that includes only the turbulence effects, we observe indeed the same level of drag reduction in both coiled and straight pipes. More complex results showing reduced drag reduction compared to curved pipes were achieved with elbows. Two elbows of different size and type were tested in turbulent flow of both water and drag-reducing surfactant solution. A more elaborate analysis was conducted for a half-inch threaded elbow with a ratio of curvature radius to diameter of 1.2. The pressure drop and heat transfer were measured in a section downstream from the elbow over a distance of x/D = 130 in order to investigate the hydrodynamic and thermal developments of the flow. The pressure drop coefficient of the elbow was calculated for water and a surfactant solution, based on the total increase in pressure drop in the system due to the presence of the elbow. For a larger welded elbow of 6″ diameter some drag reduction was measured for the surfactant solution.     

Reduction and dephosphorization of molten iron oxide with hydrogen-argon plasma

A laboratory-scale test was made in which iron oxide contained in a water-cooled crucible was melted and reduced by using a 10–50% H₂-Ar transferred arc plasma. The degree of reduction was found to be proportional to the amount of hydrogen fed. The efficiency of hydrogen utilization for the reduction was 50–70%, which is much higher than equilibrium values below 3000 K. This high efficiency was attributable partially to the reactivity of the hydrogen atom in a plasma and partially to the continuous contact of the hydrogen plasma with the molten iron oxide layer floating over the liquid iron formed. During the plasma reduction, evaporative loss of phosphorus was observed. The degree of phosphorus removal depended on the weight ratio, CaO/(SiO₂+Al₂O₃). H₂-Ar plasma was shown to be far superior for the phosphorus removal, compared with Ar and Ar-N₂ plasma.     

Electrolytic reduction of azidochalcones

Cathodic reduction of -azidochalcones under slightly protic conditions proves to be an excellent method for a selective conversion of the azido function to an amino group without affecting other reducible parts of the molecules. The amino-propenones retain theZ-configuration about the C=C-bond of the starting material, whereas N-acetyl derivatives, obtained under mildly acetylating conditions, are partially isomerised. The low reduction potential of N,N-diacetyl-enamines of this type prevents their direct one step synthesis by electrolysis of azidochalcones under strongly acetylating conditions. The voltammetric behaviour of the azides and their reduction pathway is discussed.

---

Elektrolytische Untersuchungen an Vinylaziden, 6. Mitt.Elektrolytische Reduktion von Azidochalkonen

Zusammenfassung Die kathodische Reduktion von -Azidopropenon erweist sich als ausgezeichneter Weg, um selektiv zu Enaminen zu gelangen, ohne (wie chemische Reduktionsmittel) auch andere Gruppierungen anzugreifen. Durch die Kontrolle von Protonierungs- bzw. Acetylierungsschritten lassen sich die stabileren N-Acetylamine erhalten. Das niedrig liegende Reduktionspotential der N,N-Diacetylamino-propenone verhindert, daß sie in einer Einstufensynthese bei der Reduktion der Azidochalkone unter stark acylierenden Bedingungen erhältlich sind. Das voltammetrische Verhalten der Azide und ihr Reaktionsweg bei der kathodischen Reduktion werden diskutiert.

     

Importance of search-domain reduction in random optimization

The importance of incorporating systematic search-domain reduction into random optimization is illustrated. In the absence of domain reduction, even an enormous number of function evaluations does not ensure convergence sufficiently close to the optimum as was recently reported by Sarma. However, when the search domain is reduced systematically after every iteration as recommended by Luus and Jaakola, convergence is obtained in a relatively small number of function evaluations, even when the initial search region is large and the starting point is far from the optimum.     

芳氨基硫脲类化合物的质谱研究（Ⅱ）

本文报道了五种新的芳氨基硫脲类化合物，即１－（４－溴－２－羧基苯基）－４－烷基氨基硫脲的电子轰击质谱（ＥＩＭＳ）。结果表明，该类化合物的分子离子峰（Ｍ＋）很弱，但却具有效强的［Ｍ－Ｈ］＋峰。分子离子的断裂以Ｎ－Ｎ键和Ｃ－Ｎ键的断裂为主，并伴随着六员环或四员环过渡态氢重排，生成相应的芳氨基正离子和芳肼基正离子，这两种离子继续失水或失其它小分子，从而形成一系列特征离子，包括骨架重排离子。     

Minimax estimators for location vectors in elliptical distributions with unknown scale parameter and its application to variance reduction in simulation

In this paper, we give an ever wider and new class of minimax estimators for the location vector of an elliptical distribution (a scale mixture of normal densities) with an unknown scale parameter. The its application to variance reduction for Monte Carlo simulation when control variates are used is considered. The results obtained thus extend (i) Berger's result concerning minimax estimation of location vectors for scale mixtures of normal densities with known scale parameter and (ii) Strawderman's result on the estimation of the normal mean with common unknown variance.Research partially supported by National Science Foundation, Grant #DMS 8901922.     

Electrochemical reduction of the bis(cyclo-octadiene)rhodium monocation: generation and fate of the 17-electron radical

The electrochemical reduction of the monocation of bis-(cyclo-octadiene)Rh[(COD)₂Rh⁺] has been studied in chlorinated hydrocarbons and d₆-acetone by cyclic voltammetry, chronoamperometry and exhaustive coulometry. Successive one-electron reductions are observed for the couples (COD)₂Rh⁺/(COD)₂Rh and (COD)₂Rh/(COD)₂Rh⁻ at -1.34 V vs. Fc and -1.93 V vs. Fc respectively. The 17-electron Rh(0) radical (COD)₂Rh abstracts a Cl atom from CH₂Cl₂ to give the dinuclear complex [(COD)Rh(μ-Cl)]₂ in high yield at 298 K. At subambient temperatures this reaction is suppressed and the dominant decomposition product is apparently (COD)Rh(C₈H₁₃), formed by H atom abstraction by (COD)₂Rh from solvent and/or adventitious water. Electrolysis products were characterized by electron spin resonance (ESR), nuclear magnetic resonance (NMR) and mass spectrometry. The reactivity of the radical is rationalized by a bonding model in which the lowest unoccupied molecular orbital (LUMO) is d_x²−y² with some diolefin mixing. ESR measurements are consistent with this model and suggest that the COD ligands form a ligand field around Rh which is closer to square planar than to tetrahedral.     

A review on drag reduction with special reference to micellar systems

A state-of-the-art review on drag reduction has been presented in order to bring out some important aspects of the drag reduction phenomenon and its potential for practical use. The review is biased towards micellar systems and discusses in detail the morphological differences between drag reducing polymeric and micellar systems. Work relating to polymeric systems has not been dealt in detail as it has been the subject of earlier reviews. Studies relating to biological additives as well as suspensions have been briefly mentioned without detailed discussion as their potential for practical use presently appears] to be limited.NCL-Communication No. 3384     

Positive values of non-homogeneous indefinite quadratic forms of type (1, 4)

Let Г_r,n—r denote the infimum of all number Г > 0 such that for any real indefinite quadratic form inn variables of type (r, n—r), determinantD ≠ 0 and real numbers c₁; c₂,…, c_n, there exist integersx ₁,x₂,…,x_n satisfying 0 < Q(x₁+c₁,x₂ + c₂,…,x_n + c_n) ≤(Г|Z > |)^1/n. All the values of Г_r,n—r are known except for г_1,4. Earlier it was shown that 8 ≤Г_1,4 ≤16. Here we improve the upper bound to get Г_1,4 < 12.