Children's family change: reports and records of mothers, fathers and children compared

Family change, when adults depart or arrive around children, raises policy issues. Its measurement depends upon the evidence collected and from whom. This paper compares British children's histories obtained from fathers and mothers. The evidence, on one birth cohort of parents, comes from two sources: the National Child Development Study and the ONS Longitudinal Study. The resulting account of family change is not substantially different between parents. There is some under-reporting of children not living with their fathers. This is due to under-reporting by those included in the studies and to under-representation in them of absent fathers and lone parents.     

基于不完备检测的并联系统维修决策研究

为了提高系统的可靠度,并联技术在重要系统上被广泛地采用.针对并联系统中的两冗余部件在物理性能、工作环境等方面的相似性以及检测时存在不完备的特点,提出了不完备交叉检测策略.为此研究了并联系统在此策略下的不同更新情况和相应的更新概率,以检测间隔和检测次数为优化变量、可靠度为约束、期望维修费用率为目标函数,建立了并联系统的优化维修模型.最后,通过实例验证了模型的有效性和经济性.     

An analytic hierarchy process model of group consensus

In group decision making, a certain degree of consensus is necessary to derive a meaningful and valid outcome. This paper proposes a consensus reaching model for a group by using the Analytic Hierarchy Process （AHP）. It supports people to improve their group consensus level through an updating of their judgments. In this model, a moderator suggests the most discoraant aeclslon manet to update his judgment in each step. The proposed consensus reaching model allows decision makers to accept or reject the suggestion from the moderator. This model ensures that the judgment updating is effective and the final solution will be of acceptable consistency. Finally, a numerical example is given to illustrate the validity of the proposed consensus reaching model.     

带有偏好锥的样本数据包络分析方法研究

针对传统数据包络分析方法无法依据确定参考面提供评价信息的弱点,给出了带有偏好锥的样本数据包络分析模型(PSam-C2WH)和相应的SCDEA有效性及弱有效性概念。分析了(PSam-C2WH)模型的性质以及它与传统DEA模型之间的关系,探讨了(PSam-C2WH)模型刻画的SCDEA有效性及弱有效性与相应的多目标规划非支配解之间的关系。进而,分析了决策单元在样本可能集中的分布特征、投影性质和模型含义等问题。     

基于FPGA的高性能D类功放控制器#br# 设计与实现

针对高性能音频D类功放系统,基于现场可编程门阵列（field programmable gate array,FPGA）设计,实现了一个双声道均匀脉冲宽度调制（uniform pulse width modulation,UPWM）型D类功放控制器。该控制器使用由相同子滤波器抽头级联构成的半带滤波器并时分复用乘法器,以降低可配置插值滤波器的硬件资源消耗,利用sigma-delta调制器的高开环增益,通过构造一个基于查找表的误差校正模块,以较小的硬件代价来预校正控制器使用UPWM技术在信号带宽内所带来的非线性失真。测试结果表明该控制器输出信噪比可达114 dB,互调失真仅为-97 dB。     

Simple scaling relations in geodynamics： the role of pressure in mantle convection and plume formation

Scaling relations are important in extrapolating laboratory experiments to the Earth‘s mantle. In planetary interiors, compression becomes an important parameter and it is useful to explore scalings that involve volume. I use simple volume scaling relations that allow one to extrapolate laboratory experiments and upper mantle behavior, in a thermodynamically self-consistent way, to predict lower mantle behavior. The relations are similar to the quasi-har-monic approximation. Slabs and plates have characteristic dimensions of hundreds of kilometers and time constants of 100 million years, but the volume scalings predict order of magnitude higher values in the deep mantle. The scaling relations imply that the deep mantle is a sluggish system with ancient features. They imply irreversible chemical stratification and do not favor the plume hypothesis.     

Gd2O3：Dy^3＋纳米晶的制备和发光性质研究

以Gd2O3和Dy2O3为反应物,共沉淀合成了镝掺杂氧化钆纳米粉体．研究了Gd2O3：D6^3＋的光致发光性质随着Dy^3＋掺杂浓度和煅烧温度的变化关系．通过对荧光强度与激活离子Dy^3＋离子浓度的关系研究发现,Dy^3＋在纳米Gd2O3基质中存在浓度猝灭现象,最佳掺杂浓度为0．7％．     

河南省普通高校排球运动现状的调查研究

采用文献资料法、问卷调查法、访谈法和数理统计等方法,调查了河南省普通高校排球运动的现状,对其影响因素进行了分析.结果表明,影响排球运动开展的因素主要是项目自身特点、大学生参与排球运动的动机、场地设备欠缺、领导重视不够等,并对如何推动河南省普通高校排球运动的开展及提高排球运动水平提出了可行性建议.     

相关Nakagami衰落等增益分集性能分析

针对相关Nakagami衰落等增益合并(equal gain combining,EGC)分集系统性能不存在精确解析式的问题,提出一种基于矩匹配的高效近似分析方法.该方法将各支路信号等增益叠加后的复杂衰落近似等价为α-μ分布,利用α-μ变量的统计特性获得分集系统的信噪比分布、中断概率和平均误符号率等性能表达式.仿真结果表明,该方法实现简单,计算结果与理论值非常接近,可应用于多种信道衰落下EGC分集系统的参数设计和性能评估.     

Marrow mesenchymal stem cells transduced with TPO/FL genes as support for ex vivo expansion of hematopoietic stem/progenitor cells

A new marrow-derived mesenchymal stem cell (hMSC) line that could support expansion of hematopoietic stem/progenitor cells (HSPCs) was developed. Primary hMSCs were infected with retrovirus containing Flt-3 ligand and thrombopoietin genes. CD34+ cells from cord blood were expanded with primary hMSCs or transduced hMSCs. The expansion of total nucleated cells, CD34+ cells and mixed colonies containing erythroid and myeloid cells and megakaryocytes for 2 weeks coculture with transduced hMSCs was remarkably increased. The outputs of long-term culture-initiating cells for 2 and 4 weeks coculture with transduced hMSCs were also largely increased. The expansion rates of HSPCs with transduced hMSCs were unchanged for 6 weeks. In contrast, the expansion rates of HSPCs with primary hMSCs declined drastically through 6 weeks. SCID-repopulating cell expansion with transduced hMSCs for 4 weeks was significantly higher than that of uncultured CD34+ cells and HSPCs expanded with primary hMSCs. Received 21 June 2005; received after revision 30 July 2005; accepted 24 August 2005