A note on the estimation of selective values from recaptures of marked animals when selection pressures remain constant over time

Summary An equation is given for the estimation of selective values from data obtained by mark-recapture experiments, assuming that selective pressures remain constant while the experiments are carried out. The equation does not have an explicit solution but can readily be solved using a trial-and-error method. The use of the equation is illustrated on some data reported byKettlewell et al. (1969) from an experiment involvingtypica andedda morphs of the mothAmathes glareosa. It is found that theedda morph apparently had a selective advantage of about 12% per day compared to thetypica morph and that this is significantly different from zero. Using another methodKettlewell concluded that the selective advantage of theedda morph was only 7% and that this was not statistically significant.     

A gender comparison of HIV and drug use across the rural-urban continuum

Despite the central role of women drug users in escalating AIDS statistics, there is still a limited number of studies that examine the roles of gender and drug use type in HIV seroprevalence. This lacuna in the research literature has led to significant gaps in researchers' understanding of how and to what extent women may differ in their drug-using and HIV risk behaviors compared to their better-studied male counterparts. This study, derived from a sample of 3,555 out-of-treatment drug users residing in three South Florida urban and rural communities, attempts to compare the drug usage and needle and sexual risk behaviors of male and female drug users that put them at risk for HIV infection. The overall seropositivity rate for women drug users was 26.5% compared to 19.5% for their male counterparts. Results of multivariate analyses indicate that females compared to males were 1.4 times more likely to be HIV seropositive. Risk behaviors associated with this elevated seropositivity include living arrangements, homeless status, drug use, sexual trading behaviors, and history of STDs. Furthermore, there was a strong linear relationship between drug use type and HIV seroprevalence among women drug users. Compared to those who were neither crack smokers nor injectors of illicit drugs, those who were crack smokers only were 2 times more likely to be HIV seropositive, while those who were both crack smokers and injectors were 5 times more likely to be HIV seropositive, and those who were injectors only were 6 times more likely to be HIV seropositive. These findings indicate that among women, drug abuse and its associated risk behaviors, increase the vulnerability of this population for HIV and thus render them an extremely important priority population on which to focus HIV prevention and public health efforts and programs.     

Marriage and childbirth as factors in dropping out from school: an analysis of DHS data from sub-Saharan Africa

Leaving school prematurely is often claimed to be among the most negative consequences of early marriage and pregnancy for girls in less developed countries. However, an analysis of the relative frequency with which these events actually occur or are named as reasons for leaving school reveals that, at least in the case of francophone Africa, they explain no more than 20 per cent of dropouts. To the extent that demographic events trump school or family factors as determinants of school-leaving, our data indicate that it is union formation--defined by the DHS as first marriage or cohabitation--rather than childbirth that is more likely to have this effect. 'Schoolgirl pregnancy' typically accounts for only between 5 and 10 per cent of girls' departures from school. Furthermore, the risks of leaving school because of pregnancy or marriage have declined over time with the decline in rates of early marriage and childbearing.     

信息载体演变与编辑出版活动的历史关系

信息载体的演变过程可分为四个时期:甲骨时期、简帛时期、纸质时期、电子时期。中国的编辑活动从有文字记录的文献产生就已经开始了。甲骨时期的编辑活动主要是从事文献材料的收集、分类编序,使其便于收藏和流传;简帛时期是中国编辑业务的奠基时期,中国历史上出现了书籍编辑活动;纸质时期编辑工作得到了很大的发展,在社会上逐渐形成一种专门的职业,而且其分工也越来越细,出现了不同专业的编辑业务;电子时期为编辑业务的内容和形式又开辟了新的领域。信息载体的演变与社会对信息存储、交流及传承需求之间是辩证关系。编辑活动的历史表明,社会物质生产方式的进步为信息载体演变提供了物质基础,而信息载体的演变决定着编辑活动的发展,反之,编辑活动的需求又加快了信息载体演变的进程。中国的编辑活动经历了收藏编辑、著述编辑、出版编辑和电子编辑四个阶段。     

欠发达地区政府行为公共性弱化探析

公共性是政府的根本属性,它决定了政府必须将公共利益作为政府行为的首要原则,确保公共利益得到切实维护和实现。然而,由于各种主客观原因,目前欠发达地区政府行为表现出了利益化、法外化、低效化的不良特征,导致政府行为公共性弱化。本文讨论了欠发达地区政府行为公共性弱化的现实原因,并提出了规避欠发达地区政府行为公共性弱化的路径选择。     

国家与民族地区乡村社会的重组——裕固族大草滩村的个案研究

本文通过分析2003年云南大学对裕固族大草滩村做的调查资料,运用农村社会学的相关理论,从裕固族大草滩村的现有行政体系入手,探讨文化网络内部的历史、民族因素,及其更细微的象征符号。以此,进一步分析国家政权与乡村社会的互动关系,探索国家政权渗透到乡村社会的方式和途径。     

我国家庭养老床位的研究现状

家庭养老床位为居家养老的老年人提供医、养、护相结合,各类资源整合的一体化居家养老服务,在缓解家庭照护压力、提高家庭照护专业化、减轻家庭养老经济负担等方面具有优势,但仍存在标准化建设不充分、医护资源整合不足、产品和平台待优化、补贴渠道未打通等问题。文章根据学术研究及各地实践现状进行简要梳理并提出对策,以促进我国卫生健康事业高质量发展。     

THE USE OF ARCS AND NODES FOR THE DETERMINATION OF CRITICAL PATHS IN PERT/CPM NETWORKS

The critical path in a PERT/CPM network is determined in various textbooks by finding the path with associated minimal slack for the network arcs or by finding the path with associated minimal slack for the network nodes. This paper points out that the use of nodes can result in a network path being incorrectly identified as a path of maximum length.