Population education in the United States

The most significant expansion of population education in the U.S. has occurred over the past 5-year period. The environmental movement of the 1960 decade established a foundation on which population education quickly developed in the 1970 decade and gained acceptance in the population establishment and among funding agencies. During the years 1970-1976, several private organizations became actively involved in the population education field. Several viewpoints and population education approaches are now evident in the U.S. These approaches stress different aspects of the issue: extension of family planning, individual and social awareness, demography, behavioral objectives, value analysis, environmental strategy, and inquiry. Although these approaches are diverse, the U.S. has provided a basic framework for population education. Research in population education has consisted of little more than review studies, knowledge and attitude surveys, and several studies on the appropriateness of population education in the formal college school setting. Further research is needed to identify the goals, objectives, and strategy of population education, and these studies would have to be linked to the cognitive and moral development of the student.     

《化学选择题习题集》例解

《化学选择题习题集》是供英国高中化学复习和考查化学成绩用的,内容分选择题、分类题、多种组合题、分析和计算题以及实验操作题五部分,共编有一千多道题。这些习题包括有关化学事实材料的、推理的、分析问题的以及实验操作知识和技能的内容。这些习题可以考查学生掌握化学基本概念、基础理论、基本知识和基本技能的理解程度和熟练技巧,也可以培养学生分析问题和解决问题的能力。因此,这些习题可用作检查学生知识质量的试题,也可用作高中化学复习时的练习题。 《化学选择题习题集》从1969年发行以来,近十年里被英美等国广泛采用,1977年经过更新修订,再版发行,深受高中化学教师和大学化学基础课教师的欢迎和赞许。有鉴于此,特选译各部的示范例题和解答,供教师们参考、借鉴。     

Finite element simulation of stress intensity factors in elastic-plastic crack growth

INTRODUCTION The finite element method (FEM) has been widely employed for solving linear elastic and elas-tic-plastic fracture problems. The evaluation of stress intensity factors in 2D geometries by FEM is a tech-nique widely used for non-standard crack configura-tions. Basically, there are two groups of estimation methods, those based on field extrapolation near the crack tip (Chan et al., 1970; Shih et al., 1976) and those using the energy release when the crack propagates. However…     

Trade-offs in the study of culture and development: theories, methods, and values

The commentators are unanimous in their support for our general orientation to culture and development, and for the pathways we have identified, and they suggest ways to enrich our approach to theory, methods, and values. We view their main suggestions as relating to trade-offs: between theories that highlight generalizations or exceptions; between methods that rely on one-, two-, or multiculture studies; and between values involving individuation or accommodation. Here, we describe ways to find an optimal balance in each instance.     

产训结合的方方面面

本文是国际劳工组织亚太分局高级职业培训专家麦尔南多先生在今年9月召开的产训结合国际研讨会发言摘要。     

Surgical management of gastric stump cancer： a report of 37 cases

Objective: To observe the clinicopathological characteristics of gastric stump cancer (GSC) and evaluate the benefits of radical surgery of GSC. Methods: The clinicopathological characteristics and postoperative survival time of 37 GSC patients who underwent surgery were investigated retrospectively. The survival time was compared according to the type of surgical pTMN stage. Survival curves were traced by using Kaplan-Meier methods. Results: Most GSC (32/37) was detected in patients who had received Billroth Ⅱ reconstruction after partial gastrectomy for benign gastric disease. The lesser curvature side and the suture line of anastomosis were the most frequent sites where GSC occurred (27/37). Differentiated adenocarcinoma was the dominant histopathological type (24/37). The postoperative 5-year survival rate of early stage GSC patients (n=9) was significantly higher than advanced stage GSC (n=12) (55.6% vs 16.5%, xL2=1 1.48, P＜0.01). Five-year survival rate of 21 GSC patients with radical resection were 75% (3/4) for stage Ⅰ, 60% (3/5) for stage Ⅱ, 14.2% (1/7) for stage Ⅲ, and 0% (0/5) for stage Ⅳ respectively.The median survival time of 21 GSC patients who underwent radical resection was longer than those undergoing palliative operation (43.0m vs 13.0m, xL2=36.31, P＜0.01), the median survival time of stage Ⅳ patients with radical resection was 23.8months. Conclusions: Without remote metastasis, radical resection for GSC is possible, and is an effective way to improve the prognosis of GSC. Even in stage Ⅳ GSC, radical resection can still prolong the survival time. It is necessary for the patients with benign gastric diseases who received partial gastrectomy to carry out the endoscopy follow-up, especially in patients with Billroth Ⅱ reconstruction procedure at 15-20 years.     

Global exponential stability of interval neural networks with a fixed delay

1.IntroductionConsideradelayedneural-networkmodeldescribedbythefollowingfunctionaldifferentialequations.()()()()()()11,nniiiijjjijjjijjtautwgutvgutImt===-++-+邋&1,2,,.in=K(1a)or()()()()()()ttttt=-++-+uAuWGuVGuI&,(1b)where()()()()T12,,,ntututut=轾臌uListhestatevectoroftheneuralnetwork;()12diag,,,naaa=AKisadiagonalmatrixwithpositiveentries,i.e.,0ia>;()ijnnw=Wand()ijnnv=Varetheconnectionweightmatrixanddelayedconnectionweightmatrix,re-spectively;()()()()()()()()T1122,,,nntgutgutgut轾=臌GuKde…     

Drainage after total thyroidectomy or lobectomy for benign thyroidal disorders

Objective: This prospective randomized clinical trial was conducted to evaluate the necessity of drainage after total thyroidectomy or lobectomy for benign thyroidal disorders. Methods: A total of 116 patients who underwent total thyroidectomy or lobectomy for benign thyroidal disorders were randomly allocated to be drained or not. Operative and postoperative outcomes including operating time, postoperative pain assessed by visual analogue scale (VAS), total amount of intramuscular analgesic administration, hospital stay, complications, necessity for re-operation and satisfaction of patients were all assessed. Results: The mean operating time was similar between two groups (the drained and non-drained groups). The mean VAS score was found to be significantly low in the non-drained group patients in postoperative day (POD) 0 and POD 1. The mean amount of intramuscular analgesic requirement was significantly less in the non-drained group. One case of hematoma, two cases of seroma and three cases of transient hypoparathyroidism occurred in the non-drained group, whereas one case of hematoma, two cases of seroma, two cases of wound infections and two cases of transient hypoparathyroidism occurred in the drained group. No patient needed re-operation for any complication. The mean hospital stay was significantly shorter and the satisfaction of patients was superior in the non-drained group. Conclusion: These findings suggest that postoperative complications cannot be prevented by using drains after total thyroidectomy or lobectomy for benign thyroid disorders. Furthermore, the use of drains may increase postoperative pain and the analgesic requirement, and prolong the hospital stay. In the light of these findings, the routine use of drains might not be necessary after thyroid surgery for benign disorders.     

我眼里的中美两国中学生

中国和美国是世界上有着相当大差异的两个国家。它们有可能相同吗?一般说来,这似乎是不可能的。但大多数的人对它们之间有那么多的相似之处而感到惊讶。在美国,学校一般是上午8点上学,下午3点放学:在中国则是上午7点上学,下午”点才放学。在课程设置上,