Review of Radon and Lung Cancer Risk

Radon, a long-established cause of lung cancer in uranium and other underground miners, has recently emerged as a potentially important cause of lung cancer in the general population. The evidence for widespread exposure of the population to radon and the well-documented excess of lung cancer among underground miners exposed to radon decay products have raised concern that exposure to radon progeny might also be a cause of lung cancer in the general population. To date, epidemiological data on the lung cancer risk associated with environmental exposure to radon have been limited. Consequently, the lung cancer hazard posed by radon exposure in indoor air has been addressed primarily through risk estimation procedures. The quantitative risks of lung cancer have been estimated using exposure-response relations derived from the epidemiological investigations of uranium and other underground miners. We review five of the more informative studies of miners and recent risk projection models for excess lung cancer associated with radon. The principal models differ substantially in their underlying assumptions and consequently in the resulting risk projections. The resulting diversity illustrates the substantial uncertainty that remains concerning the most appropriate model of the temporal pattern of radon-related lung cancer. Animal experiments, further follow-up of the miner cohorts, and well-designed epidemiological studies of indoor exposure should reduce this uncertainty.     

基于联合变换的旋转不变光学图像加密

利用两个彼此独立的编码脉冲相位掩模在联合变换相关器中对需要保护的图像进行编码,实现对原始图像的加密。该方法的特点是解密时加密图像的旋转不会影响解密效果,相位分布是密钥的合法持有者唯一掌握的确定性函数,可以重构,便于实际应用。计算机模拟的结果证明了方法的可行性。     

基于模态分解的Hilbert-Huang变换

Hilbert-Huang变换(HHT)是近年来发展起来的一种新的时频分析方法。本文首先阐述了基于经验模态分解(EMD)的Hilbert—Huang变换(HHT)的基本原理及英特点,然后将该方法用于实例,对比分析了HHT变换和传统的傅立叶变换的实验结杲,进而说明了该方法用于信号时频分析的可行性和优越性。     

一类下Hessenberg(0,1)-矩阵行列式的上界

文章讨论最多包含n-1个零元，且没有零元的行单独出现，有零元的列不会单独出现的n阶下Hesserlberg(0，1)-矩阵，并给出了该类矩阵行列式的上界．     

色散控制“呼吸”孤子传输特性的数值研究

采用数值计算方法研究了色散控制“呼吸”孤子传输系统稳定传输的特性,研究结果表明:脉冲的主体或“内核”部分的演化是稳定的,而脉冲所受的周期放大损耗以及色散项的扰动在归一化放大间距Z_d(Z_d)<<1条件下,该扰动对脉冲主体的影响可以忽略,从而证明了色散控制“呼吸”孤子传输是一个稳定的传输方案。     

吉尼系数逐步扩大的原因分析

我国吉尼系数偏大反映了我国收入分配领域的问题与矛盾,也带有我国经济发展过程中种种不和谐的烙印。目前吉尼系数已超过国际公认的警戒线,收入差距的扩大打破了原有的大锅饭、平均主义,带来了劳动生产率的提高。但收入差距的扩大也带来了种种问题,不利于改革的深入发展和社会的稳定。     

新员工向企业人转变的策略研究

目前国内很多企业存在着新员工流动率居高不下的现象,造成企业时间、人力和财力上的浪费,严重影响企业组织的发展和员工的士气。为了尽快使新员工转变为企业人,本文从研究新员工的价值生命周期规律着手, 利用员工满意度量化模型,提出员工的价值生命周期各个阶段提高员工满意度的策略,使企业期望的员工价值生命周期和员工自身拥有的生命周期相吻合而产生共振,从而增强员工对企业的忠诚感和归属感。     

小波变换在输电塔结构损伤位置识别中的应用

采用小波变换极大值在多尺度上的变换规律表征信号突变点的性质，从而确定信号有无奇异点并确定其位置，进而对等截面悬臂梁进行损伤位置识别。然后将该小波变换方法应用于大型输电铁塔的损伤位置识别。考虑到对大型结构施加荷载和监测变形曲线较为困难，提出了利用环境激励下的加速度响应沿高度变化的曲线作为基本信息进行小波变换的识别方法。结果表明，该方法能有效地识别沿高度刚度均匀分布或渐变的高耸格构式塔架的损伤位置，对存在刚度突变的塔架无法有效地识别刚度突变处的损伤。     

政府职能转变与体育产业发展

以体育产业发展的时代背景及体育产业化是大势所趋为前提,要推进体育产业化,关键在于政府职能的转变。为了保证各项体育产业政策的顺利实施,体育主管部门要合理定位,转变职能,以促进体育事业的发展。     

New Explicit Examples of Fixed Points of Poisson Shot Noise Transforms

The main objective of this paper is to establish a close relation between the fixed points of Poisson shot noise transforms and perpetuities of a special type. With this relation it is shown that the gamma distributions, the generalized positive Linnik distributions, and the S2 distributions are fixed points of Poisson shot noise transforms. The paper also proves that log‐convexity of the response functions is not needed for non‐negative Poisson shot noise distributions to be self‐decomposable. Finally, the problems of existence and uniqueness of the above mentioned perpetuities are investigated.