Dual Designs and Their Application in Genetical Experiments

The dual of incomplete block designs has been studied with th́eir applications in genetical experiments. Partial diallel crosses (PDC) of type I have been constructed using balanced incomplete block (BIB) designs, partially balanced incomplete block (PBIB) designs and their dual designs. Simplified analysis of PDC has been presented using the dual property of these designs. List of optimal PDC having simple analysis has been given.     

Highly efficient stepped wedge designs for clusters of unequal size

The stepped wedge design (SWD) is a form of cluster randomized trial, usually comparing two treatments, which is divided into time periods and sequences, with clusters allocated to sequences. Typically all sequences start with the standard treatment and end with the new treatment, with the change happening at different times in the different sequences. The clusters will usually differ in size but this is overlooked in much of the existing literature. This paper considers the case when clusters have different sizes and determines how efficient designs can be found. The approach uses an approximation to the variance of the treatment effect, which is expressed in terms of the proportions of clusters and of individuals allocated to each sequence of the design. The roles of these sets of proportions in determining an efficient design are discussed and illustrated using two SWDs, one in the treatment of sexually transmitted diseases and one in renal replacement therapy. Cluster-balanced designs, which allocate equal numbers of clusters to each sequence, are shown to have excellent statistical and practical properties; suggestions are made about the practical application of the results for these designs. The paper concentrates on the cross-sectional case, where subjects are measured once, but it is briefly indicated how the methods can be extended to the closed-cohort design.     

景观设计思维的培养途径与教学探讨——从设计思维的特性谈起

作为一门以落地性为特征的应用型学科,对学生规划设计思维与能力的培养一直是风景园林专业教学的重要目标,如何通过教学有效地培养学生规划设计思维与能力也成为了风景园林专业教育关注的重要议题。本文从设计思维的特性出发,针对设计教学课程提出了一套控制方式和流程,并以同济大学本科三年级上学期的公园设计课程为例,对景观设计思维的培养途径和方法展开了教学尝试。     

Experimental design methods for bioengineering applications

Experimental design is a form of process analysis in which certain factors are selected to obtain the desired responses of interest. It may also be used for the determination of the effects of various independent factors on a dependent factor. The bioengineering discipline includes many different areas of scientific interest, and each study area is affected and governed by many different factors. Briefly analyzing the important factors and selecting an experimental design for optimization are very effective tools for the design of any bioprocess under question. This review summarizes experimental design methods that can be used to investigate various factors relating to bioengineering processes. The experimental methods generally used in bioengineering are as follows: full factorial design, fractional factorial design, Plackett–Burman design, Taguchi design, Box–Behnken design and central composite design. These design methods are briefly introduced, and then the application of these design methods to study different bioengineering processes is analyzed.     

生物工程专业“试验设计与数据处理”教学中常用软件的探讨

试验设计与数据处理在生物工程专业方向有着重要的应用,但是在本科教学中开设该课程的高校较少。本文结合生物工程中的常见案例,对该课程教学过程中常用的软件包括Excel、正交试验设计助手、Data processing system(DPS)和Design expert在单因素、多因素、正交、均匀、P-B(Plackett-Burman)和响应面等数据处理方法进行了探讨。通过比较分析各种软件和数据处理方法之间特点,增加该课程教学的实践性和应用性,从而提高教学质量。     

Design-driven, multi-use research agendas to enable applied synthetic biology for global health

Many of the synthetic biological devices, pathways and systems that can be engineered are multi-use, in the sense that they could be used both for commercially-important applications and to help meet global health needs. The on-going development of models and simulation tools for assembling component parts into functionally-complex devices and systems will enable successful engineering with much less trial-and-error experimentation and laboratory infrastructure. As illustrations, I draw upon recent examples from my own work and the broader Keasling research group at the University of California Berkeley and the Joint BioEnergy Institute, of which I was formerly a part. By combining multi-use synthetic biology research agendas with advanced computer-aided design tool creation, it may be possible to more rapidly engineer safe and effective synthetic biology technologies that help address a wide range of global health problems.     

Analysis of Partially Balanced Incomplete Block Designs with Standards

The paper presents a detailed analysis of variance of PBIB designs supplemented by one or more standard treatments. Comparisons were carried out of treatment effects within the group of standard and test treatments and between the two groups. The analysis is supplemented by an example.     

On the PBB Designs for Multiresponse Experiments

We present the idea of using multiresponse incomplete block designs when not all responses can be observed in all experimental units. For a special class of such designs, in which partial designs are PBB designs, a method for estimating natural treatment contrast is given. We also consider the problem of testing the hypotheses concerning the natural and any estimable treatment contrasts. For testing this hypothesis the Wald statistics, being asymptotically chi-square distributed, is proposed.     

Sample Size Requirements in Studies of the Etiologic Fraction

This paper outlines methods of determining sample size for epidemiologic research in studies of the etiologic fraction. The basic model with a dichotomous disease and a single dichotomous exposure factor is considered. To determine sample size, the researcher must specify: the magnitude of the etiologic fraction ε to be detected as statistically significant, the level of significance α, the power 1 - β of the test, p the proportion of the population exposed to the risk factor and R the proportion of the population with the disease. Sample size formulas and tables are presented for the case-control, cohort and cross-sectional designs. Optimal allocation considerations are examined to minimize cost for a specified power. Extensive use is made of Walter's results concerning the asymptotic variance of the maximum likelihood estimator of the etiologic fraction for the three epidemiologic study designs.     

Binary Data in Prerandomized Designs

In 1979 and 1981 Zelen introduced the so-called prerandomized designs as an alternative to the completely randomized trial of therapies: The participants of the trial are first (pre-) randomized to the treatment groups and asked afterwards for their consent. In the case of binary data, tests for selection and treatment effects in the simple and double prerandomized design are derived and then illustrated by a numerical example.