Development of cycling skills in 7- to 12-year-old children

Objective: Cycling is a complex skill consisting of motor skills such as pedalling, braking, and steering. Because the ability to perform cycling skills is based on the age-related development of the child, experience and age-related reference values are of interest in light of customized testing and training.

Methods: One hundred thirty-eight children from the second (7–8 years), fourth (9–10 years), and sixth (11–12 years) grades performed a practical bicycle test consisting of 13 test items with specific points of interest. Moreover, age at onset of cycling, cycling to and from school, independent mobility, and minutes cycling per week were estimated using a parental questionnaire.

Results: It is found that cycling skills are strongly related to age with 11- to 12-year-old children outperforming 7- to 8-year-old children for 11 test items and 9- to 10-year-old children for 8 test items.

Conclusions: Next to age, age at onset of cycling also contributed to cycling skills. Therefore, our results suggest that cycling skills are associated with physical and mental maturation. Subsequently, age-related reference values are provided to customize testing and training.     

废旧巷道对含尘气流自净特性的研究

着重研究了废旧巷道对含尘气流的自净特性,进而对利用旧巷自净进行受控循环通风的设想进行探讨;在对浓度场和流体场测试的基础上,建立了粒子在废旧巷道沉降的紊流弥散模型,对边界条件进行了正确的假设,得出了稳态时的自净效率公式;导出了风量与巷道体积的关系表达式。     

Unintentional strangulation deaths from the "choking game" among youths aged 6-19 years - United States, 1995-2007

The "choking game" is defined as self-strangulation or strangulation by another person with the hands or a noose to achieve a brief euphoric state caused by cerebral hypoxia. Participants in this activity typically are youths (Andrew & Fallon, 2007). Serious neurologic injury or death can result from engaging in this activity. Recent news media reports have described numerous deaths among youths attributed to the choking game. Because no traditional public health dataset collects data on this practice, CDC used news media reports to estimate the incidence of deaths from the choking game. This report describes the results of that analysis, which identified 82 probable choking-game deaths among youths aged 6-19 years during 1995-2007. Seventy-one (86.6%) of the decedents were male, and the mean age was 13.3 years. Parents, educators, and health-care providers should become familiar with warning signs that youths are playing the choking game (Urkin & Merrick, 2006). Impact of industry: By learning about the risk factors for and warning signs of the choking game, parents, educators, and health-care providers may be able to identify youth at risk for playing the game and prevent future deaths.     

职业卫生50年回顾

职业卫生工作是政府卫生工作的一个重要组成部分 ,在党和国家的重视和领导下 ,我国的职业卫生工作在过去的 50年取得了举世瞩目的成就 ,保障了亿万职工的健康 ,保证了我国社会主义现代化建设的顺利发展。1　职业卫生法制和标准体系基本形成　　新中国建立后 ,中国人民政治协商会议通过的共同纲领中就明确地宣布 :“公私企业目前一般应实行 8～ 10ｈ的工作制” ,“保护青工、女工的特殊利益 ,实行工矿检查制度 ,以改进工矿的安全和卫生设备。”1954年通过的中华人民共和国宪法中 ,更庄严地规定了劳动者有受到国家保护的权利 ,如“逐步改善劳…     

旧路改造工程路堤稳定性安全监测方案设计

本文从旧路改造工程的特点出发,通过室内实验获取土力学参数并对沉降量进行预测计算.利用沉降仪、测斜管、孔隙水压力计、土压力盒等多种测试仪器,选取有代表性的观测断面,对经过土工格栅加筋处理的软土地基进行了高路堤施工期间的沉降与稳定观测,并提出适合工程特点的控制标准.从而达到控制路堤稳定、检验填筑质量、控制差异沉降、为路面施工提供技术支持的目的.     

东北老工业基地安全发展实践研究

沈阳是东北地区中心城市和国家重要工业基地,工业集中度位居世界大城市前列。随着社会的不断进步,安全发展已经成为振兴沈阳老工业基地的必然选择。树立安全意识、落实安全责任、整治重大安全隐患、加强安全生产工作领导是实现安全发展不可或缺的四个因素,笔者从创造和谐稳定的发展环境,实现安全、可持续发展的高度出发,对安全发展进行了深入论述,提出落实以人为本的科学发展观,坚持安全发展理念,完善政策支持,加大安全投入,强化安全监管,保持城市公共安全形势的总体稳定,为沈阳的发展和振兴营造良好环境。     

专家警告今后五十年全球森林火灾将会增加

近日在墨西哥城举行的“新千年森林火灾研究国际研讨会”预测,随着地球变暖,今后50年内全球发生的森林火灾将会增加,特别是干旱缺雨天气形成的“干雨”放电现象的增多,将对热带森林地区形成更大的威胁。 美国华盛顿大学森林资源与生态问题专家埃内斯托·阿尔瓦拉多指出,热带森林火灾产生的大气污染将占全球污染排放量的20％,它对经济造成的损失将是难以估计的。像巴西这样拥有大面积森林的国家,森林火灾的危险将会变得更加严重。 墨西哥国立自治大学大气科学中心的森林火灾专家也认为,地球温度的升高和转暖,使大气中的水     

7FA临界灭火浓度的测定及7FA/BTP协同灭火作用研究

作为氢氯氟烃、氢氟烃和全氟烃的理想替代物,七氟环戊烷(7FA)因其具有环境友好性和环状结构而极具发展潜力.首先构建了临界灭火体积分数测定平台,采用杯式燃烧器法测得7FA熄灭乙醇火焰的临界灭火体积分数为8.4％.其次,为了规避其灭火体积分数稍高的缺点,将7FA和一溴三氟丙烯(BTP)按照一定的物质的量比进行了混合,结果表明,在7FA中加入少量的BTP可以显著提高其灭火能力并将其临界灭火体积分数降低到6％以下.最后,在此试验基础上对构建的理论预测模型的可靠性进行了验证,得出7FA与BTP之间存在协同灭火作用.     

国家质量技术监督局1999年第14号公告第二批实施安全认证的机械产品目录

依据《中华人民共和国产品质量认证管理条例》,经审核,批准中国机械安全认证管理委员会对下列机械产品实施安全认证。具体事宜由中国机械安全认证中心负责。一、建筑工程机械二、采掘设备三、分离机械四、食品机械五、包装机械六、凿岩机械七、气动工具八、全属切削机床九、移动电源车十、炼油化工设备国家质量技术监督局1999年第14号公告 第二批实施安全认证的机械产品目录     

林业安全生产工作改革20年回顾

1　概　述　　林业安全生产是关系到国家和林业职工生命财产安全和林区社会稳定的大事 ,是保护和发展生产力 ,保证林业经济建设稳步发展的基本条件。　　林业产业是我国国民经济体系中一个重要的基础产业部门。统计资料表明 ,1998年林业拥有国有工业企业 4 977家 ,国企职工总数达 119.16万人 ,其中木材采运企业 132 8家 ,职工为 86.2 3万人 ,占职工总人数的 72 .4 % ,其他为木材加工 (包括三板生产 )、林产化学工业、机械制造及修理、电力和建筑等企业。　　 1978年我国实行改革开放政策以后 ,林业经济建设步伐加快 ,与此同时 ,为了给林业生…     

老虎台矿55002#掘进面通过F7-1断层前后微震事件的时空特征分析

冲击地压作为一种特殊的矿压显现形式,对抚顺矿业集团老虎台矿深部开采的安全生产造成了严重的影响,在该矿的实际生产中,地质条件是引发冲击地压发生的重要因素。鉴于微震监测系统是目前在煤矿井下监测冲击地压应用较为广泛的手段之一,本文利用波兰ARAM IS/MA微震监测系统对老虎台矿55002掘进工作面通过F7-1断层前后的微震特征信号进行连续观测,分别从时间和空间上研究此掘进面通过断层前后的微震特征,验证了一种典型的冲击地压发生时间前后的微震活动规律,并结合实际地质条件从位置上分析了微震事件与断层等地质构造之间的关系,进而根据空间分析结果圈定了重点防治冲击地压区域,使老虎台矿在该工作面掘进生产中提前采取相应的防范措施,顺利通过断层等地质构造异常区域,确保了安全生产。     

宣钢选烧厂二烧车间抓好班组安全日的经验

宣钢选烧厂二烧车间在班组安全活动日的活动中,抓活动制度的落实,抓骨干培训,抓活动内容,抓活动形式,抓活动管理五抓活动,取得了很好的效果.     

企业地面运输平车供电系统的改造

比较了国内企业地面运输平车的几种供电方式及其优缺点。介绍了地面运输平车安全供电的基本原理及特性。具有较强的实用性。     

Construing of self and others at work in the early years of corporate careers

Research has examined personal change and stability in early adulthood but generally with standardized scales and without inviting explicit comparison of self with other people. The present work uses the repertory grid method to examine how graduates construe themselves and others during early career. Ninety-four graduate entrants to a multinational corporation with zero to four years' tenure completed repertory grids on two occasions one year apart. Results shed much light on the graduates' concepts of self relative to others in their work setting, and how these change over time. The graduates generally had fairly positive self concepts, though these did not become more positive with tenure. Most saw themselves much as they thought others saw them. Change in concepts of self varied greatly between graduates, as did the constructs on which those concepts were described. The results cast further doubt on whether organizational socialization affects people in uniform ways.     

Ⅱ系统烧结机尾收尘系统存在问题分析及改进

指出了Ⅱ系统烧结机机尾CSF型收尘系统投入使用以来存在的问题 ,并对存在的问题作了详细分析 ,最后针对问题提出了相应的改进措施