Heartbeat-related fundamental frequency and amplitude variation in healthy young and elderly male voices

Modulation of the acoustic amplitude and fundamental frequency of a sustained vowel across the heart cycle was examined via signal-averaging. Ten normal young and ten normal elderly men prolonged phonations of the vowel /a/. Consistent with previous studies, the young men's maximal heart-beat-related frequency and amplitude variations averaged 1.0% and 8.4% of their respective means. Such modulation was estimated to account for 6.6% of the absolute jitter and 11.3% of the shimmer measured in these voice samples. The extent of this systematic variation was significantly greater in the older voices, averaging 2.4% of the mean frequency and 15.4% of the mean amplitude and was estimated to account for approximately 12.9% and 15.8% of their mean absolute jitter and shimmer, respectively. This age-related difference is thought to be a manifestation of involutional changes in laryngeal vascular and soft tissues and in ventilatory biomechanics.     

现代中国文化格局的迁动与新文学走向

“五四”时期，深受西方工业文明影响的精英文化 、固 有的传统农业文明文化与民间文化三足鼎立，共同构成现代中国的新文化格局。精英文化作 为主流文化不仅培植了精英文学，而且也左右了新文学的发展流向。20世纪30年代后期，意 识形态文化的霸权，改变了既成的文化态势，现实乃至政治的需要促成了新文学主体向民间 文化的靠拢，并逐渐奠立了大众文学在新文学中的领导地位。     

股市风险构成间接分解模型的改进及实证

对Campbell等提出的分析股市风险构成的间接分解模型进行改进,并运用改进模型研究中国股票市场1995年至2005年的风险构成和趋势。结果发现,公司风险是个股收益率平均风险的最大组成部分,其次是系统风险,行业风险的重要性相对较小;中国股市收益率的平均风险随时间存在下降的趋势,而公司风险和行业风险的重要性随时间在增加;总的协方差风险序列对个股收益率平均风险的影响,随时间不具有一致性。在分析股市风险构成时,不应忽略对协方差风险序列的研究。     

蒽酮高分子复合物发光体的光老化研究

通过５５５ｎｍ单色光照射下的２小时人工老化和露天中２６个月自然老化。研究了蒽酮高分子复合物发光体的光老化性质，经过２６个月的自然老化发光峰值强度下降了４８％，树脂的光透过度下降了４０％，表明光老化的原因主要是树脂老化引起的。     

一阶自回归模型参数变点的假设检验

本文讨论一阶自回归模型自回归参数$\phi$的变点问题. 对于一阶自回归模型, 在模型的白噪声序列的方差$\sigma^2$已知和未知的条件下, 利用最大似然方法, 我们分别讨论了模型自回归参数$\phi$的Abrupt Change-Point 和Gradual Change-Point的检测问题.     

Hitting time of large subsets of the hypercube

We study the simple random walk on the n‐dimensional hypercube, in particular its hitting times of large (possibly random) sets. We give simple conditions on these sets ensuring that the properly rescaled hitting time is asymptotically exponentially distributed, uniformly in the starting position of the walk. These conditions are then verified for percolation clouds with densities that are much smaller than (n log n)^‐1. A main motivation behind this article is the study of the so‐called aging phenomenon in the Random Energy Model, the simplest model of a mean‐field spin glass. Our results allow us to prove aging in the REM for all temperatures, thereby extending earlier results to their optimal temperature domain. © 2008 Wiley Periodicals, Inc. Random Struct. Alg., 2008     

机电一体化的概念衍变及其发展方向

机电一体化由“机械学”和“电子学”复合而成，意味着在传统机械产品中融入电子信息技术。本文详细介绍机电一体化的概念，并探讨其网络化、智能化、微型化和绿色化的发展方向。     

女子跳马的发展趋势和3类动作的技术要领

指出女子跳马项目的3类动作是今后发展的趋势,并对其技术要领进行了说明。     

畜牧业和谐发展之路--绿色生态养殖

绿色畜牧业乃畜牧业发展的必然趋势。现在的养殖业存在许多问题，畜产品残留物及动物排泄物影响动物本身、人类和环境，带来了一系列危害。采取措施发展绿色生态养殖，才能促进畜牧业和谐协调发展。     

Analysis of surface layers of an iron axe from Early Medieval Age

An ancient axe from Early Medieval Age which was unearthed on a territory of the archaeological excavation site near the village Borovce (Slovakia) is investigated. The surface of the axe was supposed to be covered with a sort of glassy system. Mössbauer effect measurements performed in backscattering and transmission geometry upon original as well as powdered pieces of the axe confirmed that the surface layers of the axe consist of goethite, lepidocrite, akageneite, and/or magnetite. After temperature treatment at 400°C/100 min hematite and maghemite were found; these are products of thermal decomposition of the above mentioned iron phases. These findings ruled out the hypothesis that the surface covering substance was put on the axe by intention.