Randomized trial of breast self-examination in Shanghai: methodology and preliminary results

BACKGROUND: The efficacy of breast self-examination in helping to reduce mortality from breast cancer has not been rigorously demonstrated. PURPOSE: To assess efficacy, a large, randomized trial was initiated in Shanghai, China. METHODS: From October 1989 to October 1991, 267040 current and retired female employees associated with 520 factories in the Shanghai Textile Industry Bureau were randomly assigned on the basis of factory to either a self-examination instruction group (133375 women) or a control group (133665 women). The women were born within the period from 1925 through 1958. Women in the instruction group were given intensive training in breast self-examination, including the use of silicone breast models and personalized instruction, plus two subsequent reinforcement sessions and multiple reminders to practice the technique. Women in the control group were asked to attend training sessions on the prevention of low back pain. All women have been followed for the development of breast diseases and for death from breast cancer. RESULTS: A high level of participation during the first 4-5 years of the trial was documented among women in the instruction group. Randomly sampled women in this group demonstrated greater proficiency in detecting lumps in breast models than did randomly sampled women in the control group. Approximately equal numbers of breast cancers were detected in the two groups (331 in the instruction group and 322 in the control group) through 1994, which is the last year for which case-finding efforts have been completed. The breast cancers detected in the instruction group were not diagnosed at an appreciably earlier stage or smaller size than those in the control group. More benign breast lesions were detected in the instruction group than in the control group (1457 versus 623, respectively), suggesting a higher index of suspicion for women who received training. Cumulative breast cancer mortality rates through 5 years from entry into the study were nearly equivalent for the two groups. CONCLUSIONS: Breast self-examination has not led to a reduction in mortality from breast cancer in this study cohort in the first several years since the trial began. A shift toward the diagnosis of disease at a less advanced stage in women given instruction has also not been demonstrated. Longer follow-up of participants in this trial is required before final assessment can be made of the efficacy of breast self-examination. IMPLICATIONS: At this time, there is insufficient evidence to recommend for or against the teaching of breast self-examination.     

新型缆用热熔胶的研制

分析了通信线缆用 YH- 4热熔胶组成原料的性能和作用 ,找出影响耐环境高温性能的主要原因 ,并对新研制出的耐环境高温性能 YH- 5热熔胶作了一些分析和探讨 .     

颗粒状物料气力输送系统中输料管的连接方式

对颗粒状物料的气力输送 ,人们往往只重视所要采用的输送方式 ,而忽视了输料管连接方式的正确选择、施工与安装。输料管连接方式的正确与否 ,直接影响到输送量和物料的品质。详细介绍了常用的几种连接方式 ,分析了它们的优缺点 ,并提出了比较合理的连接方式     

A modified transverse resonance method for the analysis ofmultilayered, multiconductor quasiplanar structures with finiteconductor thickness and mounting grooves

A modified transverse resonance method is presented for analyzing generalized multilayered, multiconductor quasiplanar structures with practical parameters such as finite conductor thickness and mounting grooves. Recurrence relations are obtained by using network theory for obtaining the overall transverse equivalent network. while the discontinuity involving the finite-thickness metal sheet and mounting groove is carried out by a field-theory-based multimodal variational formulation. The frequency behaviors of propagating, evanescent, and complex modes are obtained for several commonly used quasiplanar lines, showing good agreement with published results. Furthermore, a leaky-wave study is carried out for open structures, since the open condition can be included in this formulation without difficulties     

一种新型微处理器功能验证

文中介绍一种新型微处理器的验证方法，并对相关的一些验证策略进行深入的讨论。     

活塞环厂家必须重视试验研究工作

随着我国交通运输业和汽车工业的快速发展 ,使活塞环行业出现蓬勃生机。原有的活塞环厂在发展 ,新的小厂如雨后春笋般建立。活塞环市场既繁荣而又混乱。由于人们手头缺乏有说服力的科学证据 ,那些权威院所和专业厂家又不出来指点迷津 ,因此在市场的广告性宣传和商业炒作的波涛中被搞得昏头转向 ,无所适从。在此 ,不妨先举两个令人迷惑而殷切盼望答案的事例 :前段时期 ,市场上出现了 61 0 0 Q“封口环”的“专利发明”,整组活塞环的价格上扬了 5 0 %。这么赚钱的东西当然有巨大的诱惑力。大厂小厂跟着一哄而上 ,“专利”拥有者要“打假”,“…     

Al2O3基耐磨陶瓷涂层的燃烧合成与应用

介绍了燃烧合成表面涂层技术的基本原理 ,开发了相应的制备工艺 ,并在此基础上研制了内覆陶瓷涂层的复合钢管、弯管及弯头。陶瓷涂层主要由α Al2 O3相、部分FeO·Al2 O3相和 3Al2 O3·2SiO2 相组成 ,采用添加剂可以有效提高熔体的流动性 ,使陶瓷的凝固和结晶过程得到进一步控制 ,有助于减少孔隙 ,提高陶瓷涂层的致密度。现场应用试验表明 ,涂层具有较好的耐磨性能 ,可使设备的使用寿命大为延长     

硅化腐植酸钠GFN-1的研制

针对目前生产腐植酸硅化产品原料受限的缺点,在大量试验的基础上,确定了一条以腐植酸和硅化剂为主要原料的生产工艺,合成了一种与有机硅腐植酸钾(OSAM-K)性能相当的硅化腐植酸钠产品GFN-1,对其常规性能指标和在清水及无固相聚合物钻井液体系中、在膨润土浆和低固相钻井液体系中应用指标,耐温性能进行了对比实验。实验结果表明,GFN-1作为钻井液添加剂,具有良好的降滤失、降黏、耐温及热稳定性,并兼有优良的控制页岩分散能力,其大多数应用性能相当于或略优于OSAM-K,作为替代品完全能够满足油田现场应用的需要。GFN-1的硅化原料性质稳定、来源广泛,生产工艺简单易行,产品质量稳定,具有较好的推广价值。     

固液相变蓄能的数学模型和自然对流换热系数的实验研究

引入自然对流换热系数 ,将固液蓄能数学模型简化为仅用能量方程加以描述。并通过实验测得相变过程的实际温度场 ,证明了自然对流固液相变换热的影响不可忽略 ,验证了固液相变界面移动速率随自然对流换热系数的增大而增大的定性关系