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471.
The National Occupational Exposure Survey (NOES) was used to determine probabilities for 4 potential physical-agent and 10 potential ergonomic-related exposure hazards among a representative sample of U.S. industries. Potential physical-agent hazard exposures, principally whole-body and segmental vibration, were highest among railroad and heavy construction industries. Several construction industries had high probabilities of potential ergonomic-related exposure hazards, especially to the back and upper extremities.

Establishments with 100 to 249 employees had the highest probability of potential exposures to the 2 types of hazards. Measures of safety and health climate did not differ consistently between high-hazard and low-hazard establishments. The approach taken in this paper may be used to help identify highrisk industries, evaluate interventions, and develop inspection strategies.  相似文献   
472.
Reducing greenhouse gases in the atmosphere is becoming a pressing issue for the global community. Afforestation and reforestation are promoted worldwide as an effective means of sequestering carbon. For its national interest and global concerns, China has made great efforts to protect its existing forests and develop programs of afforestation and reforestation. Based on two surveys recently conducted in Liping County, Guizhou province, this paper investigates the economic changes associated with the implementation of the "Grain For Green" policy. Based on the analytical framework of benefit cost analysis, this paper concludes that the implementation of the reforestation of sloping agricultural land policy would not be possible if there were no government subsidies for the peasants. The short term economic returns of land and labour from forestation are substantially lower than those generated from grain or cash crop production on the steep slope lands. The government subsidies provide great economic incentives for peasants to take part in the project. The subsidies in fact have elevated peasant income in rural Liping. The estimated potential economic returns of plantations over the long run indicate that the removal of the government financial subsidies would not create an economic crisis for the peasants if the current market conditions continue.  相似文献   
473.
Reducing the negative impact from on-site systems and promoting recycling are important tasks for municipal authorities, especially as regards phosphorus. The objective of this scenario study was to compare energy turnover in a life cycle perspective, recycling potential and expected reduction of nitrogen and phosphorus emissions for three upgraded small-scale wastewater systems based on local recycling of plant nutrients. The systems studied were urine separation, blackwater separation and chemical precipitation in the septic tank. The urine was sanitised through storage, the blackwater through liquid composting and the precipitated sludge through chemical treatment with urea before reuse in agriculture. The system boundaries included the operational phase as well as investment in capital goods required for upgrading the existing on-site systems.The urine separation system used least energy. The potential recycling and reduction of phosphorus was lower than for the other two systems, while that of nitrogen was higher than for the chemical precipitation system but lower than for the blackwater separation system. The blackwater separation system reduced both nitrogen and phosphorus to a high extent and also enabled a large proportion of both nitrogen and phosphorus to be recycled to arable land. However, a major drawback with this system was its significantly higher use of electricity, related to the aeration and stirring required when sanitising the blackwater by liquid composting. When urea treatment replaced liquid composting, the use of electricity decreased substantially in the blackwater separation system. The chemical precipitation system was efficient in reducing and recycling phosphorus, while inefficient for nitrogen. The use of fossil fuels was significantly higher than for the other two systems, primarily due to the production of the precipitation chemical.  相似文献   
474.
A cytogenetic survey and follow-up studies were made of 14 cases with supernumerary marker chromosomes, identified among 12 699 prenatal samples, investigated at our institution over a 10-year period from 1980 to 1990. FISH (fluorescence in situ hybridization) techniques were employed to identify the chromosomal origin of the marker chromosomes. Five cases were familial, all derived from acrocentric chromosomes, and all without apparent phenotypic effects in the children. Nine cases represented de novo aberrations. In two cases (one with a marker from chromosome 14 or 22, the other with a ring-like marker derived from chromosome 17), the pregnancies continued and apparently normal babies were delivered at term, but the child with a marker derived from chromosome 17 showed slight psychomotor retardation at 2 years of age. All other pregnancies with de novo markers were terminated. In three cases, significant abnormalities were found at autopsy. One of these had an isochromosome 12p and the phenotype was consistent with Pallister-Killian syndrome. In conclusion, marker chromosome identification, as well as clinical follow-up, is essential for the purpose of improving genetic counselling.  相似文献   
475.
ABSTRACT: The precision of width and pool area measurements has rarely been considered in relation to downstream or at section hydraulic geometry, fisheries studies, long-term or along a continuum research studies, or agency monitoring techniques. We assessed this precision and related it to other stream morphologic characteristics. Confidence limits (95 percent) around mean estimates with four transects (cross-sections perpendicular to the channel center-line) ranged from ± 0.4 to 1.8 m on streams with a width of only 2.2 m. To avoid autocorrelation, transects should be spaced about three channel widths apart. To avoid stochastic inhomogeneity, reach length should be about 30 channel widths or ten transects to optimize sampling efficiency. Precision of width measurements decreased with decreased depth and increased with stream size. Both observations reflect variability caused by features such as boulders or coarse woody debris. Pool area precision increased with pool area reflecting increased precision for flat, wide streams with regular pool-rime sequences. The least precision occurred on small, steep streams with random, boulder or coarse woody debris formed pools.  相似文献   
476.
自然资源综合科学考察是基础性科技工作,对于服务国民经济和社会发展具有重要的科技支撑作用。进入21世纪,我国自然资源综合科学考察工作从低谷中逐步复苏,但依然面临科考人才断档、经费支持不足、跨国考察组织艰难、重大成果产出不多等诸多挑战。本文从地域范围、队伍组成、技术手段、成果影响等角度总结了我国综合科学考察工作的最新进展,并展望新时代,提出了我国综合科学考察研究工作的六大发展趋势,包括:从综合科学考察向自然资源综合考察研究转变;考察国际化进程将加快;注重多学科综合考察与宏观微观结合调查;考察技术将更加多样化、智能化和精准化;考察信息数据共享平台支撑能力更加强大;科考人才的培养成为紧迫需求将得到加强。  相似文献   
477.
某工业场地砷污染的加密布点优化与精度对比分析   总被引:1,自引:0,他引:1  
场地污染调查是开展场地风险评估和修复的基础,随着我国颁布建设用地土壤风险管控标准等文件,提出风险筛选值和管制值的分级管控体系,我国土壤污染调查工作对于精确掌握污染物浓度梯度及空间分布有了更高的要求,因而如何构建高效采样布点方法变得尤为重要.本研究以南京市某砷工业污染场地为例,开展了优化布点方法与调查精度的研究.首先,在初查数据的基础上,运用指示克里格的方法预测土壤污染概率,参考城市土壤背景值开展阈值设定,提取加密布点区域,之后结合场地历史生产资料与自然信息布设加密点位,最终将插值预测污染结果与非加密、均匀加密、真实情况结果进行对比,验证方法精度.结果表明:本方法符合国际中基于设计抽样以达到场地调查简单、经济、客观的理念,适用于数据存在明显空间相关性的场地;该方法获得的污染区域面积占比为8.32%,与8.57%的现实情况较为接近,但普通法得到的污染面积比相对未加密情况不升反降,可能的原因是在非污染区域增设点位会造成阈值边缘区域在模拟时往清洁区域偏移,污染区域被误判为清洁,反而造成结果偏差;在目前我国环境管理对超阈范围重点关注的背景下,该方法既能够节约布点成本,又精确化预测场地污染超标范围,为后续的场地修复和治理工作提供帮助.  相似文献   
478.
Previous studies have combined random-site hierarchical sampling designs with analysis of variance techniques, and grid sampling with spatial autocorrelation analysis. We illustrate that analysis techniques and sampling designs are interchangeable using densities of an infaunal bivalve from a study in Poverty Bay, New Zealand. Hierarchical designs allow the estimation of variances associated with each level, but high-level factors are imprecisely estimated, and they are inefficient for describing spatial pattern. Grid designs are efficient for describing spatial pattern, and are amenable to conventional analysis. Our example deals with a continuous spatial habitat, but our conclusions also apply in disjunct or patchy habitats. The influence of errors in positioning is also assessed. The advantages of systematic sampling are reviewed, and more efficient hierarchical approaches are identified. The distinction between biological and statisticalsignificance in all analyses is emphasised.  相似文献   
479.
通过对沭阳县生活垃圾的现状调查与监测,并对国内外垃圾处理技术进行比较和优化,重点介绍垃圾处理新技术ITAD垃圾处理的方法,实现垃圾完全资源化利用,具有良好的经济效益和环境效益。  相似文献   
480.
爆炸事故原因调查的研究   总被引:4,自引:9,他引:4  
爆炸事故原因调查可以提供一些有用的信息 ,以避免同类事故的发生。笔者介绍了调查爆炸事故原因所需的材料 ,提出了爆炸事故调查相关的主要内容以及爆炸现场勘查的组织指挥 ,并以一个爆炸事故的调查作为实例进行了讨论。  相似文献   
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