Refinements Introduced in the Oddy Test Methodology     

Capucine Korenberg  Melanie Keable  Julie Phippard  Adrian Doyle 《文物保护研究》2018,63(1):2-12

The ‘Oddy test’ is an accelerated corrosion test introduced in the 1970s at the British Museum to identify materials likely to emit volatile substances that could harm museum artefacts. It is carried out in many museums all around the world, but not always using the same methodology, which makes it difficult to compare and share test results between institutions. Refinements to the Oddy test methodology have been implemented at the British Museum over the last decade and the aim of this paper is to present these and promote consistency across institutions. The modifications introduced concern the method used to wash the glassware, the preparation of the metal coupons, and standard methods for preparing samples of liquid coatings, adhesives, and adhesive tapes. Finally, conducting Oddy tests is time consuming and measures employed at the British Museum to reduce the number of materials to be tested and streamline testing are described.  相似文献   

Not notable enough: feminism and expertise in Wikipedia     

Maude Gauthier  Kim Sawchuk 《传播与批判/文化研究》2017,14(4):385-402

Wikipedia promotes itself as a community that anyone can join as long as they know the rules. In this paper, we reflect on our attempt to join this community and to edit Wikientries on ageing so that they include an intersectional perspective, especially with regard to gender. Our excursion into Wikipedia reveals how certain entries act as sites of contestation between different communities of practice, such as feminist scholars and Wikipedia experts. We document and discuss three interconnected discursive guidelines over which contestation takes place: notability, verifiability, and tone. These guidelines govern the way that Wikipedia operates in relationship to dominant discourses on age and gender. They are at the heart of its inequitable treatment of content matter.  相似文献   

The influence of performance level,age and gender on pacing strategy during a 100-km ultramarathon     

Andrew Renfree  Everton Crivoi do Carmo  Louise Martin 《European Journal of Sport Science》2016,16(4):409-415

The aim of this study is to analyse the influence of performance level, age and gender on pacing during a 100-km ultramarathon. Results of a 100-km race incorporating the World Masters Championships were used to identify differences in relative speeds in each 10-km segment between participants finishing in the first, second, third and fourth quartiles of overall positions (Groups 1, 2, 3 and 4, respectively). Similar analyses were performed between the top and bottom 50% of finishers in each age category, as well as within male and female categories. Pacing varied between athletes achieving different absolute performance levels. Group 1 ran at significantly lower relative speeds than all other groups in the first three 10-km segments (all P < 0.01), and significantly higher relative speeds than Group 4 in the 6th and 10th (both P < 0.01), and Group 2 in the 8th (P = 0.04). Group 4 displayed significantly higher relative speeds than Group 2 and 3 in the first three segments (all P < 0.01). Overall strategies remained consistent across age categories, although a similar phenomenon was observed within each category whereby ‘top’ competitors displayed lower relative speeds than ‘bottom’ competitors in the early stages, but higher relative speeds in the later stages. Females showed lower relative starting speeds and higher finishing speeds than males. ‘Top’ and ‘bottom’ finishing males displayed differing strategies, but this was not the case within females. Although pacing remained consistent across age categories, it differed with level of performance within each, possibly suggesting strategies are anchored on direct competitors. Strategy differs between genders and differs depending on performance level achieved in males but not females.  相似文献   

一种引入强制变异的改进遗传算法     

孔祥蕾  张先燚  罗晓琳  李海洋 《中国科学院大学学报》2003,20(3):316-320

针对常用遗传算法存在容易产生过早收敛的问题,提出了一种将强制变异、最佳解保留和自适应交叉变异参数调整相结合的改进遗传算法。这种方法将进化过程中群体的平均适应度与最大适应度进行比较,以确定是否需要对群体实施强制变异或采用自适应交叉、变异概率调整。数值模拟的结果表明,这种方法可有效地克服早熟现象,提高全局优化能力  相似文献   

“十三五”时期中国人口发展面临的挑战与对策     

张车伟  林宝 《湖南师范大学社会科学学报》2015,(4)

“十二五”时期中国人口持续保持低速增长,人口老龄化程度不断加深。预测表明,中国劳动年龄人口及比例将不断下降,人口老龄化将以世界上少有的速度快速提高,总人口将在2026年左右达到高峰后开始下降。“十三五”时期中国人口发展将面临人口结构失衡、劳动力供给下降、养老服务需求快速增长、城镇化转型等多方面的挑战。为应对这些挑战,必须尽快全面放开二孩生育,转变经济发展方式和开发人力资源,大力发展养老服务业,积极推进新型城镇化等。  相似文献   

我国优秀艺术体操运动员早衰现象及其致因探讨   总被引：6，自引：2，他引：4  

樊莲香  邝丽 《北京体育大学学报》2001,24(1):112-115

近年来 ,我国许多优秀的艺术体操运动员在没有被充分挖掘其训练潜力 ,还未达到事业顶峰的时候或有的在达到个人高峰期仍然有较高的竞技水平时就中止训练 ,离开了赛场 ,过早地结束了运动寿命、削弱了艺术体操本就匮乏的优秀运功员队伍和后备力量 ,影响了人才梯队的衔接 ,甚至出现了运动队伍的“断档”,造成了国家人力、物力、财力的严重浪费 ,影响着我国艺术体操竞技水平的提高。所以 ,揭示我国艺术体操运动员的“早衰”现象 ,分析其致因 ,寻找预防对策 ,有着重要的现实意义。  相似文献   

具有成熟前收敛判断的自适应遗传算法   总被引：9，自引：0，他引：9  

袁晓辉  曹玲  夏良正 《东南大学学报》2003,19(1):40-43

针对传统的简单遗传算法的缺陷，提出了改进的具有成熟前收敛判断的自适应遗传算法．用群体熵值和均方差来预报成熟前收敛的发生．当成熟前收敛发生时，提出以群体中的最优个体为基础，在其一定大小领域内随机产生若干个体，取代原种群中的部分个体，其中更新的个体数占群体中个体总数的30％—40％，领域大小与目标函数极值点分布有关．仿真实验证明，算法的收敛速度和全局收敛概率都有显的提高．  相似文献   

老年人的居住环境探讨     

张会平 《湖南城市学院学报》2003,24(6):47-48,53

论述了我国人口老龄化的形势，养老模式及养老观念的变化，老年人生理和心理变化．结合我国国情，探讨了有益于老年人的养老模式及老年居住环境中应着重解决的问题．  相似文献   

中日韩三国老龄化问题的比较研究   总被引：1，自引：0，他引：1  

吴霞 《中国软科学》2003,(3):9-13

发端于欧洲的现代化，使人口动态从多产多元死向少生少死转变。现代化不仅引起了欧洲的老龄化，同时也波及到美国、日本等国家，中国和韩国也已步入老龄化国家。随着全球老龄化现象的加剧，由老龄化所引发的各种问题，都将随着时代的推移而日渐明显。本文产要对中国，日本及韩国老龄化的现状进行分析和比较，找出老龄化所带来的问题，并对其进行考察和研究，明确今后在这方面所要研究的课题。  相似文献   

老年与老年前期骨钙素和血钙的测定分析     

朱建中  葛炜 《科技通报》1996,12(4):252-253

对１５６例健康中老年人进行血清骨钙素和血清钙的含量测定。结果表明，血清骨钙素水平男性要比女性，高，但两者都低于绝经后的妇女，而血钙随着增龄，有逐步下降的趋势。提示老年人，尤其是绝经后妇女由于骨转换加快，骨吸收增加会导致血清骨钙素含量升高，血钙下降。  相似文献