The heritability of cognitive functioning in very old adults: Evidence from Danish twins aged 75 years and older.

Heritable influences on cognitive functioning were investigated in a sample of 403 pairs of like-sex Danish twins aged 75 years and older. Twins completed the Mini-Mental State Examination and 3 other cognitive tests. Genetic factors accounted for 26–54% of the variance on these measures, with the balance being due to environmental factors that create differences rather than similarities among reared-together relatives. Deleting twins with severe cognitive impairment had little effect on the results, indicating that the heritability of cognitive functioning was not due entirely to genes affecting dementia. Neither age nor gender moderated twin similarity, and differential social contact could not account for correlation differences between monozygotic and dizygotic twins. These results replicate G. E. McClearn et al.'s (1997) study in indicating substantial genetic influences on late-life cognitive functioning. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

三相VFT电压测量中电场耦合系数矩阵的确定

在三相快速瞬变过程ＶＦＴ（Ｖｅｒｙ Ｆａｓｔ Ｔｒａｎｓｉｅｎｔｓ）电压测量中,需要３个电容传感器,而每个传感器同时受Ａ、Ｂ、Ｃ三相电压的电场耦合。该文讨论了三相同壳式封闭式组合电器ＧＩＳ（Ｇａｓ Ｉｎｓｕｌａｔｅｄ Ｓｕｂｓｔａｔｉｏｎ）在完全对称布置和不完全对称布置情形下,电场耦合系数矩阵的确定方法。提出了主导电场耦合系数的概念,给出了它的近似解析表达式。     

下寺湾式岩性封闭裂缝油藏的建立

在下寺湾油田裂缝高产井泉5925-3和5915井延伸线上所布置的桦3井,采到含油的张性裂缝岩心,取得 丰富的油气地质信息。原油分析对比表明,相邻的两个裂缝高产井和相距较远的一个裂缝高产井,其原油都是 以低碳烃为主的特低凝原油,但与紧邻的正常产量井原油同源异性。这说明本区的裂缝高产井有着相同的成藏 地质过程,并且成片、成带、有规律分布,把这种油藏命名为下寺湾式岩性封闭裂缝油藏。研究这种油藏的形成 及分布规律,将为鄂尔多斯盆地油气勘探打开一个新的领域。     

特高含水期油田动态监测系统优化技术研究

对大庆油田目前所有的注入剖面和产出剖面测井技术进行了优化研究.在油藏数值模拟的基础上,得到试验区块的模拟吸水剖面和产出剖面,与测井得到的吸水剖面和产出剖面进行了对比分析.为了使两者之间有可比性,对小层流量进行了合理的劈分或合并,求出两者之间的样本偏差.其结果可以用于制定下一步动态监测方案,从而达到对试验区块的动态监测系统的优化,为充分挖掘试验区块剩余油及提高采收率提供依据.     

基于偏心Preissmann格式的高速互连线分析

 将偏心Preissmann格式应用于高速电路互连线分析,导出一种互连线离散模型.通过调整偏心参数,可以获得二阶精度的差分格式.数值仿真表明,该方法能够应用于一般互连线的瞬态分析,改善间断之后的数值扰动现象,并与特征法进行了比较,说明了方法的有效性.     

基于局部形相似的超短期负荷预测方法

在对电力负荷局部特性分析的基础上,定义了一个描述负荷序列形状相似程度的指标--负荷曲线形系数,提出了一种基于局部形相似的超短期负荷预测方法.该方法将预测时刻前一段负荷序列与各相似日同一时段负荷序列的形系数引入到超短期负荷预测中,强调基于形相似基础进行值预测,克服了现有预测方法中对各相似日采用相同权重所导致的平滑效应对拐点负荷预测的影响.研究结果表明,该方法在保证运算速度的同时,提高了总体预测准确性和拐点处的预测准确性.该改进方法可用于对现有多种超短期负荷预测方法的改进.     

The Dynamic Changes of Proton Efflux Rate in Saccharomyces pastorianus Strains During High Gravity or Very High Gravity Brewing

The changes in the proton efflux rate (PER) during fermentation of normal gravity (NG), high gravity (HG) and very high gravity (VHG) wort by a lager yeast (Saccharomyces pastorianus) were monitored using an optimized PER test method. The values of the proton efflux rate in S. pastorianus decreased with increasing initial wort gravity. Moreover, the difference in the proton efflux rate values at the beginning of the fermentation was lower than at the end of fermentation from normal gravity to very high gravity brewing. These results demonstrated that the proton efflux rate in S. pastorianus was inhibited in the later stages of high gravity and very high gravity brewing. Furthermore, the changes of the proton efflux rate in S. pastorianus under the high ethanol concentration conditions appeared to depend on the concentration of ethanol in the fermentation liquid. A better negative correlation (P > 0.001, r = ?0.95) between the ethanol concentration at >4% (w/v) and the proton efflux rate was found. The changes of the proton efflux rate in the cells treated with exogenous ethanol confirmed that higher concentrations of ethanol could significantly inhibit proton efflux in S. pastorianus. This study offers a possible way to monitor and explain the performance of yeast in the complex environment of high gravity and very high gravity brewing.     

特快速瞬态过电压和雷电冲击作用下特高压GIS绝缘特性

随着电压等级的提高,气体绝缘开关设备(GIS)的额定雷电冲击(LI)耐受电压和特快速瞬态过电压(VF-TO)水平的差异越来越小,由VFTO引起的绝缘事故也日益严重。为研究特高压GIS在VFTO下的绝缘耐受水平,设计了VFTO模拟产生装置,研究了不同气压下SF6棒-板和球-板间隙在VFTO和雷电冲击下的绝缘特性。实验结果表明:稍不均匀电场间隙在VFTO下的击穿电压高于雷电波;对于高气压下棒-板间隙,负极性VFTO下的击穿电压和伏-秒特性曲线位于雷电波之下;雷电冲击下棒-板间隙极性效应在一定的气压下会出现反转现象。分析表明:在不同冲击波前和振荡波尾的VFTO和雷电波作用下SF6气体间隙击穿特性的差异与放电过程中空间电荷行为的差异有关。     

2.5MV特快速瞬态过电压发生器

气体绝缘开关设备（gas insulated switchgear,GIS）以其占地面积少、密封性好,受环境影响小,运行可靠、维修周期长等优点在中国电网中得到了广泛应用。在330kV以上电压等级的系统中,开关动作产生的特快速瞬态过电压（very fast transient overvoltage,VFTO）对系统有很大危害。为满足特高压GIS中VFTO的模拟,利用6MV敞开式冲击电压发生器与陡化装置结合的方法,研制出一种模拟VFTO产生的装置。通过增加GIS母线长度来补偿回路固有电感的影响,以及通过控制陡化间隙的击穿电压来控制输出电压幅值,使该装置可以输出幅值为2.5MV、高频振荡达到35 MHz的电压波,能够满足特高压试验对VFTO模拟的要求。采用外加积分器方式,制作了一种锥形电容传感器来测量该装置产生的电压波,测试结果表明该电容传感器可以满足试验的要求。     

特高压输电线路对电视信号接收的影响研究

论述了多分裂输电线路对电视信号的干扰影响机理,利用解析法得出了多分裂输电线路对电视波的散射场的计算公式。计算了特高压4分裂及8分裂线路对电视信号的干扰影响,得出了各种情况下散射场的分布曲线,包括电视波入射角、电视波频率、观测点位置等对散射场分布的影响规律。对多分裂导线对电视信号的多次散射所引起的共振态和反共振态进行了具体分析,提出了有效减少输电线路对电视信号影响的具体办法。