Assessing interactions for fixed‐dose drug combinations in subcutaneous tumor xenograft studies

Drug combinations in preclinical tumor xenograft studies are often assessed using fixed doses. Assessing the joint action of drug combinations with fixed doses has not been well developed in the literature. Here, an interaction index is proposed for fixed‐dose drug combinations in a subcutaneous tumor xenograft model. Furthermore, a bootstrap percentile interval of the interaction index is also developed. The joint action of two drugs can be assessed on the basis of confidence limits of the interaction index. Tumor xenograft data from actual two‐drug combination studies are analyzed to illustrate the proposed method. Copyright © 2013 John Wiley & Sons, Ltd.     

A note on estimation in a minimum-type model with an exponential factor

The problem of estimating the parameter Q appearing in the distribution function of a continuous random variable T=min{T₁,T₂} is considered, when T₁,T₂ are non-negative independent random variables such that T₁ has an exponential distribution with scale parameter θ and T₂ has a possibly defective distribution function G₂(t) that is G₂(∞) < 1. It is shown that the estimator proposed by Gertsbach [(1967) Theory of Probability and Its Applications, 12 is weekly consistent and asymptotically normal. The merit of this estimator is that the above properties do not depend even on the form of G₂(t) except that G₂(t) and its derivative vanish at zero.     

家用太阳能电池板自动跟踪太阳光系统设计与应用

本文设计一种能够自动跟踪太阳光的电池板发电系统。设计中以单片机技术为核心,通过模数转换对电池板发电电压进行采样,由系统对采样信号进行分析,来驱动直流电机转动电池板,实现自动跟踪太阳光的效果,从而达到提高发电效率的目的。     

胚胎干细胞研究的伦理问题与对策

目前,伦理问题是制约人类胚胎干细胞研究的主要因素。笔者分析了不同来源的人类胚胎干细胞的属性及其伦理问题,并结合我国的实际情况,提出我国应当持有的关于胚胎干细胞研究的态度与对策。     

红色音乐传播的时代价值

植根于民族艺术的红色音乐,在革命战争的年代中迸发,经历过血雨腥风的洗炼,度过了漫长的峥嵘岁月,得到了和平环境的雨露滋润,受到改革开放浪潮的激励,已经形成中国音乐艺术的一支奇葩。其优美、抒情,且健康、激扬的红色音调深受广大群众的喜爱。研究它的育人价值,把红色歌谣的情感诉求、红歌流行的百姓情结、红色音乐的社会贡献和红色音乐的教学运用发挥出来,有利于弘扬主旋律,推动社会文明的发展。     

A note on the within-cell layout problem based on operation sequences

The existing studies in the literature usually ignore the within-cell layout problem while forming part families and manufacturing cells. A new approach is proposed to solve the part-family and machine-cell formation problem and to determine the spatial arrangement of machines in each cell simultaneously. Furthermore, a dissimilarity measure between parts based on operation sequences is presented since the operation sequences not only specify the type of machine tools needed but also impact the flow of material. As a result, we can both minimize the material handling cost and streamline the material flow in each cell.     

Addendum to fitting polynomials to main effects in multi factor experiments: A note concerning polynomial coefficients when all factors are quantitative

When all factors are quantitative, cell means may be expressed as a polynomial function of products of powers of the associated quantitative classification variables. Existence and uniqueness of this polynomial is established for unbalanced data with unequal spacing for no missing cells. The relationship between the coefficients of this polynomial and the main effects polynomials are derived for main effects which are arbitrary weighted averages of the cell means.     

Graph colouring approach for cell formation problems

This paper presents a graph-theoretic approach for solving the clustering problem in group technology. The machine-component incidence matrix is used to form the weight matrix. Using the two weight matrices, one for the machines and the other for the parts, two graphs are developed. The nodes of each graph are coloured using the proper colouring method. An edge, whose adjacent nodes are of same colour, partitions the graph into subgraphs, thus creating machine-part cells. This cell formation method yields solutions which compare favourably with respect to other available methods. This procedure is illustrated using an example problem from the literature.     

关于细胞生物学本科教学的探索与思考

细胞生物学是高等学校生物类专业的必修课程之一，针对细胞生物学的课程特点，总结几年来教学过程中的实践经验，提出有助于提高教学效果和增强学生学习兴趣的几点体会。     

AQC柱前衍生高效液相色谱法测定动物细胞培养基中氨基酸

以α-氨基丁酸为内标,6-氨基喹啉基-N-羟基琥珀酰亚氨基甲酸酯为柱前衍生试剂,用高效Nova-PakC18柱,乙酸钠溶液(pH5.70)和60%乙腈为流动相,采用二元梯度洗脱,紫外检测器在248nm波长检测,建立了一种新的柱前衍生反相HPLC法同时测定动物细胞培养基中谷氨酰胺在内19种氨基酸。方法重现性好,精密度高。氨基酸的峰面积—浓度线性范围为20～500μmol/L,线性相关系数均大于0.99,峰面积的精密度为1.55～10.8%。在该色谱条件下获得了良好的商用细胞培养基DMEM和F12中氨基酸的色谱图,为动物细胞生长代谢研究提供了有利的实验手段。