Algorithm for constrained delaunay triangulation

A direct algorithm for computing constrained Delaunay triangulation in 2-D is presented. The algorithm inserts points along the constrained edges (break lines) to maintain the Delaunay criterion. Since many different insertions are possible, the algorithm computes only those that are on the Delaunay circles of each intersected triangle. A shelling procedure is applied to put triangles together in such a way that completeness and correctness are guaranteed.     

Directional decisions for two-tailed tests: Power, error rates, and sample size.

One imposing directional decisions on nondirectional tests will overestimate power, underestimate sample size, and ignore the risk of Type III error (getting the direction wrong) if traditional calculations—those applying to nondirectional decisions—are used. Usually trivial with the z test, the errors might be important where α is large and effect size is small or with tests using other distributions. One can avoid the errors by using calculations that apply to directional decisions or by using a directional two-tailed test at the outset, a conceptually simpler solution. With a revised concept of power, this article shows calculations for the test; explains how to find its power, Type III error risk, and sample size in statistical tables for traditional tests; compares it to conventional one- and two-tailed tests and to one- and two-sided confidence intervals; and concludes that when a significance test is planned it is the best choice for most purposes. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Instructor reputation: An expectancy relationship involving student ratings and achievement.

Instructor reputation, defined as student expectations of an instructor's teaching ability, was investigated to determine its influence on student ratings and achievement. Two teaching behaviors, instructor expressiveness and lecture content, were combined with reputation in a 2–3 factorial design to assess interaction effects. 198 undergraduates read an introductory statement about an instructor (reputation), viewed a videotape lecture, rated the instructor, and took a test. Results indicate that reputation interacted with expressiveness but not content, in which students rated the positive, high-expressive instructor more favorably than the negative, high-expressive instructor. Results suggest a complex relationship in which reputation interacts with some teaching behaviors and affects some student outcomes. (24 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A randomized trial to evaluate the effectiveness of dietary advice by practice nurses in lowering diet-related coronary heart disease risk

BACKGROUND: Dietary factors are an important contribution to the high rates of coronary heart disease in the UK. One approach to achieving change is health-promoting advice in primary care. AIM: To compare the effectiveness of structured dietary advice by practice nurses with standard health education in changing serum cholesterol, weight and diet. METHOD: Randomized, controlled trial within eight general practices in England and Wales allocated within matched geographical pairs to 'dietary advice' or 'usual care'. Men and women aged 35-59 years, recruited opportunistically by their GPs, underwent health checks. In 'dietary advice' practices, subjects received dietary advice from specially trained nurses based on negotiated change principles, reinforced at follow up. In 'usual care' practices, subjects were only given standard health education materials. RESULTS: A total of 956 patients were recruited: 473 in 'dietary advice' practices and 483 in 'usual care' practices. Compliance with annual follow up was 80%. Compared with 'usual care' practices, there was a mean 0.20 mmol/l lower serum cholesterol (95% CI -0.38 to -0.03 at 1 year) in 'dietary advice' practices. There was a small fall in weight of 0.56 kg (95% CI -1.04 to -0.07) and reductions in total and saturated fat. Factor VII coagulant activity fell by a mean of 6.7% of the standard (95% CI -15.4 to +2.0). CONCLUSION: Provision of standard health education material alone as part of a health check had no effect on coronary heart disease risk factors. There were modest changes in diet and associated risk factors when a more intensive and individual approach to dietary advice was given by practice nurses. This is, however, probably an ineffective use of resources, except in those at high risk of coronary heart disease. Whole-population strategies to achieve dietary change are required.     

Securing the future for nylon

Since its introduction over 50 years ago, nylon has proved a highly useful fibre in the clothing industry. In this article, Les Jacques looks at developments which have been made in nylon fibres to ensure its continuing importance in the industry.     

数码相机的DSP SoC设计方法

数码相机(DSC)正在高速增长,这要归功于技术进步带来的新功能和图象质量及易用性的改善——能在完成图象拍摄后将其打印出来,以及在功耗、成本方面的降低和画面存储能力的提高。尽管无数的厂商正在涌入该市场,推出的相机档次从300美元到数千美元不等,瞄准的目标既有照相机-计算机用户,也有普通消费者,不过也要看到,数码相机仍然不同于传统的胶片照相机。本文将探讨消费型照相机更为复杂的设计问题,包括用于提高数码相机品质与可用度的各项技术以及解决这些复杂的设计问题所需要采用的各种新方法。当前的数码相机包括以下几个方面:新型透镜…     

A comparative study of the differences between client continuers and dropouts at two university counseling centers.

Examined the differences between clients who dropped out of counseling after the intake interview and clients who continued. 87 Ss, who were randomly selected from 2 universities, were studied in terms of their attitudes and perceptions of counseling and the counseling center. Data were collected through a 27-item questionnaire consisting of 3 scales adapted from a questionnaire by J. Snyder, C. Hill, and T. Derksen and a 4th scale formulated by the author. Results indicate that continuers generally had more positive responses than dropouts and that clients from the 2 universities differed in the frequency of positive responses. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A highly accurate, inexpensive procedure for computing theoretical chronoamperometric current at cylindrical wire electrodes

Cylindrical wire or fiber electrodes are attractive for electro-analytical applications, but the theory of transient methods at such electrodes is complicated, implying that theoretical discussions and experimental data analysis usually rely on various approximations. In particular, a number of approximate expressions has been proposed in the literature to describe the chronoamperometric limiting current at such electrodes. All these expressions have a low accuracy. In the present work a new, highly accurate and computationally inexpensive procedure for computing the current is presented. The procedure relies on local polynomial approximations covering the entire time domain, and provides at least 14–15 significant digits. It can therefore be useful both for theoretical purposes (e.g. as a source of reference values for testing electrochemical digital simulation techniques that are usually less accurate), and for the analysis of the experimental data.