Efficient estimation for the proportional hazards model with bivariate current status data

We consider efficient estimation of regression and association parameters jointly for bivariate current status data with the marginal proportional hazards model. Current status data occur in many fields including demographical studies and tumorigenicity experiments and several approaches have been proposed for regression analysis of univariate current status data. We discuss bivariate current status data and propose an efficient score estimation approach for the problem. In the approach, the copula model is used for joint survival function with the survival times assumed to follow the proportional hazards model marginally. Simulation studies are performed to evaluate the proposed estimates and suggest that the approach works well in practical situations. A real life data application is provided for illustration.     

论科学劳动成果的经济性质

就科学领域本身的劳动,即尚未在物质生产中实现的那种科学劳动而言,这种劳动主要是脑力活动,是创造性活动.它的产品是精神产品,如关于自然、社会和思维规律的知识以及在社会实践中运用这些规律的知识等.情报学领域的科学劳动性质则是通过加工原始情报,获取新情报,实现知识的"流通".一般说来,要使知识和思想成为人们的财产,首先它们必须具有体现其存在的物质形式,包括语     

The development of science achievement in middle and high school. Individual differences and school effects

Using data from the Longitudinal Study of American Youth (LSAY), hierarchical linear models (HLMs) were used to model the growth of student science achievement in three areas (biology, physical science, and environmental science) during middle and high school. Results showed significant growth in science achievement across all areas. The growth was quadratic across all areas, with rapid growth at the beginning grades of middle school but slow growth at the ending grades of high school. At the student level, socioeconomic status (SES) and age were related to the rate of growth in all areas. There were no gender differences in the rate of growth in any of the three areas. At the school level, variables associated with school context (school mean SES and school size) and variables associated with school climate (principal leadership, academic expectation, and teacher autonomy) were related to the growth in science achievement. Initial (Grade 7) status in science achievement was not associated with the rate of growth in science achievement among either students or schools in any of the three areas.     

On changes in the age composition of the population and policy options for population planning

This analysis, based on 1978 data from official household registers, suggests that the 1983-2000 period will be critical for China's efforts to control population growth. If declines in the fertility rate are maintained, the possibility of stabilizing China's population at 800-900 million in the next century is feasible. If the population is to be kept under 1.2 billion by the year 2000, the general fertility rate must be lowered to 1.8 in 1985 and must decline 0.1 each 5 years thereafter until it reaches 1.5 in the year 2000. Once population growth is brought under control, it will be necessary to address consequent increases in the median age of the population. Those over 65 years of age will comprise 7.1-7.8% of the population in the year 2000, depending on whether fertility rates are low or high. The medium projection includes a population of 1.211 billion in the year 2000, approaching the peak value but allowing the fertility rate to rise slowly to guard against excessive aging of the population. The proportion of those over 65 years of age reaches a peak value of 20.2% in the year 2040. Overall, these projections suggest a "golden age" continuing until about 2020 in which the proportion of those both over 65 years and under 15 years will be rather low. The dependency ratio should begin to climb after 2020, reaching a peak in 2040 and stabilizing by 2070 at a level slightly higher than that existing today in developed countries. Since a rational age composition and a suitable decrease in the proportion of dependents are essential for economic growth, future analyses should focus on the quality of the population and not just population size. As long as birth rates continue to fall, the proportion of the dependent population will also fall and have a beneficial effect on China's economic development.     

蒙古人民共和国的佛学研究

蒙古的哲学和社会政治思想史渊远流长,古印度佛学对蒙古哲学的发展有一定的影响。蒙古的哲学家继承和发展了古印度基本的辩证逻辑,他们认真地研究了古印度思想家龙树、提婆、无著、世亲、陈那、法称、月称、寂天、寂护、莲花戒等人的经典著作,并为之作了     

蒙古民间文学研究情况

蒙古民间文学的搜集、研究、出版工作,是从人民革命胜利后的头一年,即一九二一年十一月组建我国科研中心——学术委员会时开始的。一九二三年我们首次用俄文整理出版了《阿尔吉宝尔吉汗》、《魔尸的故事》、《喀尔喀车臣汗的传说》等书。从革命初期开始我们就注意了这类故事、传说的出版工作,并较多地注意了民间口头文学、     

卫拉特史诗中的英雄副手问题

Б.Л.弗拉基米尔佐夫院士在《蒙古卫拉特英雄史诗》里,根据对于卫拉特史诗的分析,对英雄副手的形象,做出了一个特具兴味的看法:“卫拉特史诗里,和主要英雄在一起的,经常是自己的朋友,二把手勇士,每每在一部长篇史诗里,总有这样一个人物涌现我们面前,二把手性格受到优美生动、突出的刻划或描写,史诗把这类英雄副手极为详细地报导给读者”。(IC.46)     

十七世纪的一份手稿

同许多民族一样,蒙古人也崇拜天、地和火。这些仪式以口头的传说或书面文献的形式流传至今。1964年,笔者在科布多省的布尔干县获得一份不长的手稿,题名为“■”(祭火和消除 Kqen-e 之经)这份手稿极为罕见,因而我们把它刊布如下;     

《蒙古秘史》地名考

苏联蒙古学家符拉基米尔佐夫在一九二六年写道:《秘史》中出现的名称多已不为人们所知”。但是,近时经学者们研究探索,《秘史》中的地名多已解决。经过研究,《秘史》里约有百分之七十的历史地名已经考出。若想查清我们蒙古地区的古今地名,究其移名之因,考其名不传世之由,既可从民间口头文学创作中探求,也可查阅古今     

How to begin a new topic in mathematics: does it matter to students' performance in mathematics?

The authors use Canadian data from the Third International Mathematics and Science Study to examine six instructional methods that mathematics teachers use to introduce new topics in mathematics on performance of eighth-grade students in six mathematical areas (mathematics as a whole, algebra, data analysis, fraction, geometry, and measurement). Results of multilevel analysis with students nested within schools show that the instructional methods of having the teacher explain the rules and definitions and looking at the textbook while the teacher talks about it had little instructional effects on student performance in any mathematical area. In contrast, the instructional method in which teachers try to solve an example related to the new topic was effective in promoting student performance across all mathematical areas.