The effects of male age on semen parameters: analysis of 1364 men attending an andrology center

Although the effect of maternal age on fertility is well known, it is unclear whether paternal age also affects fertility. The aim of this retrospective study was to establish an association between the age of the individuals from Medellin, Colombia with semen volume, rapid progressive motility (a), total progressive motility (a?+?b) and concentration. We evaluated semen volume using a graduated tube, progressive motility using light microscopy (40×) and sperm concentration using a Makler Chamber. Semen samples were grouped according to age into three arbitrary groups (≤ to 30 years; between 31 and 39 years; and ≥ to 40 years). The semen volume, rapid progressive motility (a) and total progressive motility (a?+?b), concentration and total sperm count were found to be inversely related to age (p?<?0.05). The reduction in semen parameters of 1364 men attending an andrology center was associated with increasing age of the individuals.     

Planning for the 1950 Censuses of Population and Agriculture

The change from the z of “Student's” 1908 paper to the t of present day statistical theory and practice is traced and documented. It is shown that the change was brought about by the extension of “Student's” approach, by R.A. Fisher, to a broader class of problems, in response to a direct appeal from “Student” for a solution to one of these problems.     

On computer generation of gamma random variables by rejection and composition procedures 2

The paper presents various algorithms for generating gamma random variables, by combining rejection and composition procedures. Two efficient algorithms are given for the case when the parameter of the gamma distribution is 0<v<l. For the case vl, several algorithms are given but they (except one), work reliably only for small values of v. Results of some computer tests together with FORTRAN subroutines are also presented.     

A class of Shrunken estimators for normal mean

This paper presents a class of estimators for the mean of a normal population and determines the conditions on characterizing scalars under which the class of estimators uniformly dominates over the conventional sample mean according to the mean-square-error criterion.     

“按劳分配”评议

马克思关于未来共产主义社会初级阶段实行按劳分配原则的设想有其特定的前提和内涵;至今没有哪个国家具备这种前提条件;我国至今实行的按劳分配实际上不是也不可能是马克思设想的那种原则;应当从我国正在进行的社会主义市场经济改革和社会经济发展的实际水平出发来确定正确的分配原则。     

要素所有者的谈判力与企业权益分配格局

在全面解释“谈判力”涵义的基础上,着重论证了谈判力与企业权益分配格局的关系,并据此提出了改进我国企业权益分配状况的建议。     

马克思对"人的价值"之类命题的批判

马克思认为"人的价值"之类的命题在本质上是资本主义经济的思想反映.因而,它决非是关于人的本性、尊严和幸福的永恒观念,而仅仅是资产阶级的特殊要求、愿望和幻想的反映.它同共产主义的世界观是根本对立的.在共产主义社会中,新的命题"每一个人的自由发展"将取代陈腐的命题"人的价值".     

“分配不公”的社会学解读

当前在我国普遍存在的“分配不公”现象 ,有使社会向恶性运行和畸形发展方向退化的趋势。针对“分配不公”产生的原因 ,必须从政治理念、制度重建、政策调整、文化重建等多方面入手 ,解决“分配不公”问题 ,实现社会良性运行和协调发展     

算子的型与指标选择

本文定义了弱*(p,q)型算子,并且通过对强(p,q)型算子指标选择结论的推广,得到了弱(p,q)型算子以及弱*(p,q)型算子指标选择的结论。     

康乾时期京师文化的繁荣及其国际影响

"康乾盛世"是中国封建社会的辉煌时期,它在政治、经济、文化等很多方面,将中国传统社会推向了一个新的高峰。作为"康乾盛世"的核心,京师北京不可避免地在亚洲乃至世界的某些范围内受到人们的特别关注。在清代,朝贡体系覆盖了东亚的大部分地区,北京城处于这个体系中的核心地位。北京城对于朝贡国的影响力,不仅依托政治上的强势,也表现在思想文化上的强势。京师强势文化的产生,除了国家强盛的大背景之外,还有一系列的特殊的出自朝廷的高端文化举措。康乾时期另一个重要的文化现象是,进一步与西方文化接触,开始了超越朝贡体系的国际交往。历史显示,北京是古老文化的宝库,又是引领中国走向世界的先锋。北京的历史发展有其独特的经验,对其进行认真的总结,可以获得重要的启示。