Estimating Contaminant Dose for Intermittent Dermal Contact: Model Development, Testing, and Application

Assessments of aggregate exposure to pesticides and other surface contamination in residential environments are often driven by assumptions about dermal contacts. Accurately predicting cumulative doses from realistic skin contact scenarios requires characterization of exposure scenarios, skin surface loading and unloading rates, and contaminant movement through the epidermis. In this article we (1) develop and test a finite-difference model of contaminant transport through the epidermis; (2) develop archetypal exposure scenarios based on behavioral data to estimate characteristic loading and unloading rates; and (3) quantify 24-hour accumulation below the epidermis by applying a Monte Carlo simulation of these archetypal exposure scenarios. The numerical model, called Transient Transport through the epiDERMis (TTDERM), allows us to account for variable exposure times and time between exposures, temporal and spatial variations in skin and compound properties, and uncertainty in model parameters. Using TTDERM we investigate the use of a macro-activity parameter (cumulative contact time) for predicting daily (24-hour) integrated uptake of pesticides during complex exposure scenarios. For characteristic child behaviors and hand loading and unloading rates, we find that a power law represents the relationship between cumulative contact time and cumulative mass transport through the skin. With almost no loss of reliability, this simple relationship can be used in place of the more complex micro-activity simulations that require activity data on one- to five-minute intervals. The methods developed in this study can be used to guide dermal exposure model refinements and exposure measurement study design.     

语境规约下的民航通话英语语音改造

民航通话英语作为一种ESP英语,其特殊的语言使用环境赋予它很多自身的特点。研究民航通话英语语音改造,能发现民航英语的语用语境对其语音改造具有规约性:民航语境首先通过对语义的约束,从而在发音、声学、听觉方面制约民航通话英语语音改造。     

印度对华化工产品反倾销的贸易效应分析

随着印度对华化工产品反倾销的频发,其所产生的贸易效应越发值得关注。通过构建半对数线性回归方程,以10位编码的化工行业涉案产品的月度数据作为基础进行实证检验,考察不同阶段贸易破坏效应和贸易转移效应的存在性及其大小,指出印度对华化工产品采取反倾销措施不仅会对我国产生负的贸易破坏效应,同时会引起竞争国对印出口增加,存在正的贸易转移效应。然而对于不同产品,破坏效应出现的时间和大小是有区别的,贸易转移效应则并非普遍存在。     

提高TiO2光催化降解性能的途径研究进展

TiO2半导体作为光催化剂降解难降解有机污染物有其独特的优势,它的光解效率与光量子效率有很大的关系.本文主要从提高光量子效率着手,用改变 TiO2的晶体结构、TiO2的晶体改性及外加物质辅助光催化等方法,分析提高光催化降解性能的途径.     

基于矩阵打分值和化学位移值预测酶蛋白质中β-发夹模体

酶是一类具有催化功能的蛋白质,对其结构和功能的研究是非常有必要的。特殊模体β-发夹是一种简单的超二级结构,它们包含了丰富的折叠信息,对酶中β-发夹的预测有助于酶结构和功能的预测。本文建立了非冗余的β-发夹模体数据集,包含1080条酶蛋白质链,2818个β-发夹模体,1098个非β-发夹。提取位点亲疏水组分及位点亲疏水紧邻关联组分作为参数,运用矩阵打分算法得到的预测结果不理想。将位点亲疏水、位点亲疏水紧邻关联组分为参数得到的打分值和平均化学位移值共同作为特征参数,输入支持向量机算法对模体进行预测,5交叉检验预测总精度是81.8%,相关系数达到了0.636。     

室内设计中点线面要素的应用研究

“设计”是一个经常使用的概念,设计是在明确目的指导下的有意识的创造。室内设计是人们在满足自身需求的基础上对建筑的内部空间进行合理的功能划分、技术创新,以及艺术上的审美观的综合设计。点、线、面是作为构成抽象形态造型的要素,空间构成的基本单位。在室内设计中,点、线、面处处可见,它们之间相互影响、相互陪衬、相互烘托、相互存在、相互作用。文章从室内设计的风格、室内陈设的研究出发,对室内设计中点、线、面的运用进行思考分析。     

加入WTO对黑龙江省石化行业的影响与对策

加入WTO给黑龙江省石化行业带来新的机遇。黑龙江省石化行业应采取“有所为,有所不为”的方针,加大技术开发力度,调整技术开发队伍结构,同时采取以高起点,高水平进行统一规划和布局的总体对策。     

Sensitivity studies of air scattered neutron dose from particle accelerators

Sensitivity analysis of air scattered neutron dose at several distances from a particle accelerator with respect to shield thickness and neutron yield distributions has been carried out. We illustrate the successful use of Response Surface Methodology in studying the behaviour of the sensitivity coefficients for main effects and interaction terms. A comparison of the full six factor design and the orthogonal Central Composite Design has been made. The overhead shield is found to be the most sensitive parameter followed by the high energy part of the neutron energy distribution.     

Cutting Experimental Designs into Blocks

Most experimental material in agriculture and industry is heterogeneous in nature and therefore its statistical analysis benefits from blocking. Many experiments are restricted in time or space, and again blocking is useful. This paper adopts the idea of orthogonal blocking of Box & Hunter (1957) and applies it to optimal blocking designs. This approach is then compared with the determinant-based approach described in the literature for constructing block designs.     

Testing for parameter constancy in the time series direction in panel data models

We propose tests for parameter constancy in the time series direction in panel data models. We construct a locally best invariant test based on Tanaka [Time series analysis: nonstationary and noninvertible distribution theory. New York: Wiley; 1996] and an asymptotically point optimal test based on Elliott and Müller [Efficient tests for general persistent time variation in regression coefficients. Rev Econ Stud. 2006;73:907–940]. We derive the limiting distributions of the test statistics as T→∞ while N is fixed, and calculate the critical values by applying numerical integration and response surface regression. Simulation results show that the proposed tests perform well if we apply them appropriately.