Economic contribution of rural children and the family fertility behavior: a rationale for high fertility in India

"This paper aims at analysing the economic contribution of children and its effect on parental decisions. It is shown that, under conditions of [India's agricultural structure,] the children's contribution towards family resources is highly valued by parents, and this acts as an incentive to raise more...children. Thus, high fertility in rural areas of India can be justified in so far as the positive net economic contribution of children is highly valued by parents."     

Preventing premature death: tobacco treatment services for employees

This article presents a summary of current information concerning the health and financial costs of workplace smoking, with special emphasis on the costs to union workers and multiemployer health and welfare funds. It describes the potential savings from investing in tobacco cessation for workers and members, provides an overview of scientific evidence concerning the efficacy of different approaches to tobacco cessation, including behavioral services and medications, and discusses some of the benefit design and management issues involved in offering tobacco cessation services to employees and members.     

俄罗斯改革的教训与前景

作者对俄罗斯改革的全过程进行了总结。俄罗斯的改革同中东欧相比,尤其同中国相比是不成功的。俄罗斯在转轨过程中遭受了巨大的痛苦和灾难,普京时期经济虽有较大增长,但也不是市场化改革的成果,而是由于石油涨价和出口优势等某些特殊因素带来的。俄罗斯改革主要的教训在于,政治精英们在西方的建议下选择了错误的“休克疗法”。他们无论就其道德水准、政治上的成熟、起码的诚实和良心,还是对国家和人民的责任的理解,都绝对不能适应历史转折的召唤。许多东西表明,保留社会主义的过去的优点是有利的。     

Externalities in migration

"The paper presents a model which shows that the probability of migrants being mobile after migration depends on the number of previous waves. The model concludes that low order waves provide positive externalities to higher order waves. This conclusion is empirically tested by comparing the interindustry mobility of two sequential waves of political migrants to Israel."     

基于仿真驱动的机载光电吊舱转接法兰优化设计

无人机光电吊舱的本体与机体之间往往需要通过转接法兰进行组装,在机载有效载荷轻量化要求越来越高的今天,转接法兰在减重的同时自身结构性能也不能对光电吊舱性能造成影响。充分考虑工程设计中的实际情况,基于Ansys Workbench平台中Design Modeler模块进行转接法兰参数化建模,随后在静强度分析基础上进行响应面优化和拓扑优化,从尺寸和构型两个角度得到优化后的候选模型,经综合分析后在设计软件中进一步进行可制造修正,最终得到转接法兰的数字样机模型。该方法可以在工程实践中指导光电吊舱转接法兰的优化设计。     

30GHz单片接收机

已经研制成功30GHz接收机用的几种单片集成电路.低噪声放大器芯片在14dB增益时噪声系数为7.dB,中频放大器在30dB控制范围内,增益为13dB.混频器和移相器变频损耗和插入损耗分别为10.5dB和1.6dB.     

PC局域网网卡选购心得

宽带接入已经逐渐深入到普通家庭中。同时,许多家庭也同时拥有2-3台电脑,这样,网卡就成为家庭用户必不可少的设备之一了。但是在选购中很多人只知道一些如单口、双口,10M、100M的简单参数。这样一些不法奸商,就利用消费者对此知之甚少的便利,以次充好,牟取暴利。针对市场上这种混乱的现状,笔者特向广大消费者介绍一些网卡相关知识,方便大家选购时参照。速度对普通消费者来说,10M和10/100M自适应网卡都是不错的选择。从目前的网络应用上看,单纯的访问外部网站的瓶颈并不在用户的网卡速度上,而在出口带宽上,10M网卡访问国外的站和100M的网卡访问国外的站的速度并没有任何差别。但是随着网络的飞速发展,视频点播等服务的出台,10M的肯定不行了。所以建议还是一步到位购     

Inflatable rescue boat-related injuries in Queensland surf lifesavers: the epidemiology - biomechanics interface

The objective was to describe the relationship between epidemiological and biomechanical factors in the causal pathway of inflatable rescue boat (IRB)-related injuries in Australian surf lifesavers; to develop epidemiological and biomechanical methodologies and measurement instruments that identify and measure the risk factors, for use in future epidemiological studies. Epidemiological and biomechanical models of injury causation were combined. Host, agent and environmental factors that influenced total available force for transfer to host were specified. Measurement instruments for each of the specified risk factors were developed. Instruments were piloted in a volunteer sample of surf lifesavers. Participant characteristics were recorded using demographic questionnaires; IRB operating techniques were recorded using a custom-made on-board camera (Grand RF-Guard) and images of operating techniques were coded by two independent observers. Ground reaction forces transmitted to the host through the lifesaver's feet at the time of wave impact were measured using a custom-built piezoelectric force platform. The demographic questionnaire was found practical; the on-board camera functioned successfully within the target environment. Agreement between independent coders of IRB operating technique images was significant (p < 0.001) with Kappa values ranging from 0.5 to 0.7. Biomechanical instruments performed successfully in the target environment. Peak biomechanical forces were 415.6N (left foot) and 252.9N (right foot). This study defines the relationship between epidemiological and biomechanical factors in modifying the risk of IRB-related injury in a population of surf lifesavers. Preliminary feasibility of combining epidemiological and biomechanical information has been demonstrated. Further testing of the proposed model and measurement instruments is required.