个人积累制和现收现付制下养老金均衡收益率的影响因素分析

分析养老保险模式从现收现付制向个人积累制转轨过程中可能存在的问题,并给出政策建议．建立个人积累制和现收现付制下的经济增长模型,对均衡收益率的影响因素进行分析,并揭示其政策含义．利用Samuelson-Diamond重叠代模型推导2种制度下的平衡增长路径,对有关参数进行比较静态分析．当现收现付制下出现居民储蓄不足时,向个人积累制过渡,可以改进经济效率;当储蓄过度时,转轨则可能导致经济效率下降．不论采用哪种制度,养老金的增长均有赖于有效劳动人口的增长和劳动生产率的提高．当人口年龄结构面临不利变动时,养老金增长的重要途径是发展教育产业,增加人力资本投资．     

基于中原组团发展的中原金三角竞争力提升研究

郡县治则天下治。县城作为农村之首,城市之尾,聚集了不少非农业人口,是地域性经济文化中心,是城市化发展的节点,是大城市连接小城镇的桥梁和纽带,在推动城镇化战略中必将扮演重要角色。在中原城市群中以郑州、洛阳、许昌三市为顶点的三角区域里,有六个文化相同、地理位置相连的县(市)的发展尤其令人瞩目,被称为区域经济强县统筹发展组团——中原组团,这六个县(市)连同龙头巩义市一起,形成了中原城市群的隆起区,为郑州、洛阳、许昌三市国内生产总值(GDP)名列河南省的第一、第二和第四位作出了贡献,而这三市GDP的总和占中原城市群的57%,约为全省的三分之一,使郑、洛、许三市经济发展成为名副其实的中原金三角。     

城市交通信号三级模糊滑动优化控制方法

提出一种城市交通信号三级模糊滑动优化控制方法.引入非冲突车流的搭接相位构建交通信号三级模糊控制器的模型,并采用滑动时间窗设计滑动优化的框架.根据实时采集的交通数据,采用基于黄金分割的混合遗传算法,在线学习模糊控制器的隶属函数及控制规则参数.在常态及事故不同交通条件下,以典型路口进行Paramics仿真试验.结果表明提出方法的自适应能力好,可快速响应路口交通流的不确定性事件,且在高饱和的交通条件下性能稳定.     

Interfamily pregnancy and expression of CD57, CD68 in deciduas between golden hamster and mouse

Pregnancy between different species is one of the key steps to interspecific somatic cell cloning. Although interspecific clone embryos have been constructed, they could not develop to birth after being transferred to recipi-ents. In order to clarify the mechanism of this phenomenon, interfamily pregnancy between golden hamste (Mesocricetus auratus) and mouse (Mus musculus) was studied. Co-culture results indicated that the adhesion ratios of golden hamster blastocysts on mouse uterine epithelia monolayer 12, 24, 48 and 72 h after co-culture were all significantly lower than those of mouse blastocysts. The outgrowth ratios of golden hamster blastocysts on mouse uterine epithelia monolayer 48, 72 h after co-culture were both significantly lower than those of mouse blastocysts (P < 0.01). Golden hamster抯 blastula could be implanted and develop to D 11 of pregnancy after being transferred to mouse uterus (the 7th day after embryo transfer). Compared to the transfer of mouse embryo to mouse uterus, the successful ratio of interfamily embryo transfer was lower and the bulk of fetus was smaller than that of intraspecific fetus. Compared to intraspecific preg-nancy of mouse, the remote decidual tissue of interfamily pregnancy on D8 is looser. At the same time, expressions of CD57 and CD 68 in remote deciduas were both higher than those in the secondary deciduas in both intraspecific and interfamily pregnancy. However, expressions of the two molecules in interfamily pregnancy were lower than those in intraspecific pregnancy. These results showed that interfam-ily pregnancy could be established between golden hamster and mouse. But the development of fetus in interfamily pregnancy was slower than that in intraspecific pregnancy. The expression difference of CD57 and CD68 indicates the difference of immunoreaction between interfamily and in-traspecific pregnancy, which may be one of the reasons lead-ing to interfamily pregnancy termination.     

外来生物福寿螺入侵的生态风险及其评价探讨

通过对福寿螺生态风险较全面的分析,认为福寿螺不仅会对水稻产生直接的危害,而且会对水生生态系统的生物多样性和水体环境造成直接和潜在的危害。同时,福寿螺在特定空间和时间内具有种群暴发的风险以及向我国长江以北地区继续迁移与扩散的风险。在此基础上,进一步提出了有关福寿螺入侵的生态风险评估的概念框架。该研究结果可为控制与预防福寿螺的危害发生提供相关科学依据与参考。     

Short-distance homing in a small mammal: the role of exteroceptive cues and path integration

Summary When hoarding food under IR light, the golden hamster returns to its nest by path integration after an active outward journey, and it is capable of compensating the angular component of a passive outward journey independently of auditory, olfactory, tactile and geomagnetic cues. If, however, peripheral visual cues are available, they predominate over information which is gained during the active or passive outward journey. Further experiments show the limitations of homing by path integration, which is open to cumulative errors and therefore needs to be complemented by other categories of information.Acknowledgments. This research was supported by the Fonds national suisse de la recherche scientique, grants No. 3.349.0.74 and 3.753.0.80. We are very grateful to Dr J. Bovet, Dr W. Heiligenberg, Dr J. G. Mather and to an unknown referee for their critical comments and to Mr R. Schumacher for all his ingenious technical help.     

色彩黄金分割配色法在多媒体课件开发中的应用研究

基于黄金分割理论,运用数理分析方法,采用实例验证,研究了黄金分割在多媒体课件配色中的理论与方法。     

“黄金分割”中的数学美

"黄金分割"作为初中数学选修课中的教学内容,自身拥有极其丰富的文化背景,是学生体会数学文化,感悟数学美的机会.往往这样的数学课程很容易上成纯粹的"美术课"、"欣赏课",学生很难从数学上体会到美感,也不知道数学美何在?基于这样的考虑,本文先从学生的直接经验(模特腿较长产生的美感)导入本课,接着从数学理论上分析"美"之所在,使学生初步感受数学美.借助比例线段知识得到黄金数,再由此过程中产生的比例方程引发连分式,体会有限与无限的联系.最后利用"黄金分割"解释生活中的现象,培养学生的应用意识.通过整个过程,使学生体会数学与生活以及数学内部之间的联系,从中产生数学美.     

铝卷径向等效导热系数的仿真

利用铝板退火加热实验采集到的温度,通过热传导反问题的求解,求得铝板间的等效导热系数,将其等效为铝卷径向导热系数,并推导出铝卷强对流传热系数对温度的数学表达式,从而构建更准确的铝卷退火的温度场模型.运用ANSYS有限元分析软件,综合考虑铝卷的导热系数和对流换热系数随温度变化的非线性,模拟铝卷退火过程中的瞬态温度场.仿真结果表明:在退火的开始阶段,铝卷外表面与芯部温差较大,最高达173 ℃;在保温阶段,铝卷内部温差逐渐减小,温差只有3 ℃,最后稳定在545 ℃,与实测结果较吻合,证明所建立的数学模型是可靠的,同时,为铝卷退火工艺的优化提供了理论依据.     

内蒙古通辽地区出土的鲜卑金饰牌及其历史文化蕴涵

公元20世纪80年代至90年代初，横贯内蒙古通辽市中部地区的新开河流域，出土了三批八件鲜卑金饰牌。这些埋藏于地下1800年左右的金饰牌，无论造型艺术、纹饰图案厦实际用途均带有一种神秘色彩。鲜卑金饰牌不仅反映了古代鲜卑人的历史足迹，而且是萨满巫师通达上天和祖先，沟通自然万物神灵的圣物，亦是古代欧亚草原文化交流的有力佐证。