A Sensitivity Analysis of an Integrated Modelling Approach to Assess the Risk of Wind-borne Spread of Foot-and-mouth Disease Virus from Infected Premises

The sensitivity of an integrated model to assess the potential for wind-borne spread of foot-and-mouth disease (FMD) to variations in key parameters controlling different physical and biological processes was evaluated. The estimated number of farms at risk is sensitive to the virus strain used and the accompanying effective contact rate. The C Noville strain increased the estimated number of exposed farms ranked as high and medium risk of being infected by a factor of 5, compared to the baseline, based on the O UKG 2001 strain. The inclusion of a model for biological ageing of the virus can also have a significant effect on the concentration patterns arising from transport and dispersion of the virus. Its inclusion has the practical advantage of markedly reducing the time required for the calculations. The estimated number of farms affected by exposure to high and medium virus concentrations is not grossly sensitive to attenuation caused by temperature or relative humidity effects. Changes in susceptibility to infection, as determined by the parameter θ in the exposure-risk model, does not change the configuration of the virus plumes, but it does change the distribution of farms at risk by risk category. These findings suggest that a good understanding of characteristics (excretion rates from infected animals, susceptibility of different species to infection, virus survival, etc.) of the virus strain involved in an FMD outbreak is necessary to provide a reliable assessment of the risk of wind-borne spread. In the event of an incursion of FMD, provision for laboratory studies on the virus will be an essential component of the disease response and should be factored into contingency plans.

Design and validation of a practical index for trauma assessment

In the past 20 years a variety of indices have been suggested for measuring the severity of trauma, however none of them meets the requirement of being a simple and objective instrument that can be utilized efficiently by lay persons and providers of health services without previous experience in triaging. A new system has been proposed which meets this requirement and which has been validated with 197 injured persons at the emergency ward of the Valle University Hospital in Call, Colombia. The instrument showed a high level of concordance with the conventional triaging method and classifies victims into four categories: critical with recovery unlikely, critical but recoverable, moderately serious, and ambulatory. There is discussion on the reliability of this instrument and it is recommended that it be validated with victims from larger disasters. Regardless, it has the advantage of being specific and free of the subjectivity that characterizes other indices.     

Inorganic nitrogen metabolism inUlva rigida illuminated with blue light

Inorganic nitrogen metabolism in blue light was studied for the green algaUlva rigida C. Agardh collected in the south of Spain (Punta Carnero, Algeciras) in the winter of 1987. NH₄ ⁺ has been reported to inhibit NO₃ ^- uptake; however,U. rigida showed a net NO₃ ^- uptake even when the NH₄ ⁺ concentration of the external medium was three or four times greater than the concentration of NO₃ ^-. NO₃ ^- uptake rates were similar in both darkness and in blue light of various photon fluence rates (PFR) ranging from 17 to 160 mol m^-2 s^-1. Since NO₃ ^- uptake is an active mechanism involving the consumption of ATP, respiratory metabolism can provide enough ATP to maintain the energetic requirement of NO₃ ^- transport even in darkness. In contrast, NO₃ ^- reduction inU. rigida was highly dependent on the net photosynthetic rate. After 7 h in blue light, intracellular NO₃ ^- concentrations ([NO₃ ^-] _i ) were higher in specimens exposed to intensities below the light compensation point (LCP) than in those incubated at a PFR above the LCP. When PFR is below the light compensation point, NO₃ ^- reduction is low, probably because all the NADH produced by the cells is oxidized in the respiratory chain in order to produce ATP to maintain a steady NO₃ ^- transport rate. The total nitrogen (TN) and carbon (TC) contents decreased from darkness to 33 mol m^-2 s^-1 in blue light. In this range, catabolic processes prevailed over anabolic ones. In contrast, increases in TN and TC contents were observed above the light compensation point. The C : N ratio increased with light intensity, reaching a stable value of 17 at 78 mol m^-2 s^-1 in blue light. Intracellular NO₃ ^- concentration and NO₃ ^- reduction appear to be directly controlled by light intensity. This external control of [NO₃ ^-]_i and the small capacity ofU. rigida to retain incorporated NO₃ ^-, NO₂ ^- and NH₄ ⁺ ions may explain its nitrophilic character.     

Study on the regional atomized dust suppression technological system based on the measured law of dust concentration distribution in longwall fully mechanized mining faces

Environment, Development and Sustainability - In order to reveal the distribution and migration law of downwind and upwind coal cutting, total dust (TD) and respirable dust (RD) concentration...     

Gauging the environmental efficiency with ecological compensation in presence of missing data using data envelopment analysis

Environment, Development and Sustainability - The ecological compensation mechanism is regarded as the direction for the future management of the ecological environment of the river basin, which...     

Sustainable development of China's regions from the perspective of ecological welfare performance: analysis based on GM(1,1) and the malmquist index

Environment, Development and Sustainability - Ecological welfare performance is a measure of the relationship between input ecological resources and output welfare, and it reflects the sustainable...     

Study on cooperative strategies of rural water environment governance PPP project between companies and farmers from the perspective of evolutionary game

Environment, Development and Sustainability - The PPP mode of rural water environment governance was conducive to attracting social capital for giving full play to the decisive role of the market...     

华北区域点冬季二次有机气溶胶特征与影响因素

为探明二次有机气溶胶(SOA)的污染特征和影响因素,本研究于2018年11月—2019年1月对华北区域点(德州市郊区点)细颗粒物(PM_(2.5))的化学组成进行了在线测量,并分析了PM_(2.5)中有机碳(OC)、元素碳(EC)和水溶性离子组分的污染特征及PM_(2.5)与气象要素之间的相关性.结果表明,观测期间德州PM_(2.5)污染严重,平均质量浓度为(115.6±24.6)μg·m~(-3);其中,有机碳和元素碳是PM_(2.5)的主要成分,平均质量浓度分别为(8.2±5.8)μg·m~(-3)和(2.6±2.2)μg·m~(-3),占PM_(2.5)总质量的7.1%和2.2%;PM_(2.5)与风速呈负相关,与相对湿度呈正相关,与气温的相关性较差,偏北风对PM_(2.5)浓度影响较大.同时,本研究利用EC示踪OC/EC比值法对PM_(2.5)中的二次有机碳(SOC)进行了估算,通过估算得到的SOC结果表明,华北区域点冬季SOC是OC的重要组成部分,平均浓度为(4.0±2.9)μg·m~(-3),占OC的45.7%,SOC在白天占比较高(62.7%),早晚由于有局地生物质燃烧影响,SOC占比降低,约占OC的42.7%.本研究还分析了SOC生成的影响因素,分析了德州市冬季O_3、含水量、酸度与SOC的相关性.结果表明,SOC受臭氧浓度影响,但在白天和夜晚表现出不同的相关关系,可能存在不同的生成机制.最后,利用ISORROPIA模型估算了颗粒物的含水量和酸度,发现SOC在高含水量和低含水量下存在不同的关系,高含水量更能促进SOC生成;在高含水量下SOC与H~+具有显著相关性,但在低含水量下则不相关,表明颗粒物含水量较高、H~+浓度较高情况下液相酸催化反应可能对SOC具有重要贡献.     

Dynamic nano-Ag colloids cytotoxicity to and accumulation by Escherichia coli: Effects of Fe3+, ionic strength and humic acid

Released Ag ions or/and Ag particles are believed to contribute to the cytotoxicity of Ag nanomaterials, and thus, the cytotoxicity and mechanism of Ag nanomaterials should be dynamic in water due to unfixed Ag particle:Ag⁺ ratios. Our recent research found that the cytotoxicity of PVP-Ag nanoparticles is attributable to Ag particles alone in 3 hr bioassays, and shifts to both Ag particles and released Ag⁺ in 48 hr bioassays. Herein, as a continued study, the cytotoxicity and accumulation of 50 and 100 nm Ag colloids in Escherichia coli were determined dynamically. The cytotoxicity and mechanisms of nano-Ag colloids are dynamic throughout exposure and are derived from both Ag ions and particles. Ag accumulation by E. coli is derived mainly from extracellular Ag particles during the initial 12 hr of exposure, and thereafter mainly from intracellular Ag ions. Fe³⁺ accelerates the oxidative dissolution of nano-Ag colloids, which results in decreasing amounts of Ag particles and particle-related toxicity. Na⁺ stabilizes nano-Ag colloids, thereby decreasing the bioavailability of Ag particles and particle-related toxicity. Humic acid (HA) binds Ag⁺ to form Ag⁺-HA, decreasing ion-related toxicity and binding to the E. coli surface, decreasing particle-related toxicity. HA in complex conditions showed a stronger relative contribution to toxicity and accumulation than Na⁺ or Fe³⁺. The results highlighted the cytotoxicity and mechanism of nano-Ag colloids are dynamic and affected by environmental factors, and therefore exposure duration and water chemistry should be seriously considered in environmental and health risk assessments.     

杭州湾北岸36种挥发性有机物污染特征及来源解析

为研究杭州湾北岸VOCs（挥发性有机物）的浓度水平、组成特征、反应活性和潜在来源,采用GC-FID在线监测系统对杭州湾北岸环境大气中的36种VOCs开展了为期1 a（2017年12月-2018年11月）的连续观测,采用LOH（VOCs的·OH消耗速率）和OFP（O₃生成潜势）2种方法估算了大气VOCs的反应活性,并利用PMF（正定矩阵因子分解）和CPF（条件概率函数）模型分析其来源.结果表明:①φ（VOCs）小时平均值在冬季（26.47×10-9）最高,夏季（9.76×10-9）最低;全年φ（VOCs）小时平均值为21.24×10-9,其中烷烃、烯烃+炔烃、芳香烃、卤代烃的贡献率分别为33.24%、34.13%、15.63%、17.00%;φ（烷烃）、φ（芳香烃）和φ（卤代烃）呈较明显的昼夜变化特征,φ（烯烃）和φ（炔烃）无明显昼夜变化趋势.②大气VOCs的总LOH和OFP分别为9.39 s-1和220.57 μg/m3,KOH（·OH反应速率常数）和MIR（最大增量反应活性）系数的平均值分别为17.34×10-12 cm3/（molecule·s）和3.31;KOH和MIR系数的平均值分别与间/对-二甲苯的KOH和乙苯的MIR系数接近,表明大气VOCs的化学反应活性较强;VOCs关键活性物种为异戊二烯、乙烯、丙烯、甲苯、二甲苯和顺-2-丁烯.③特征物种相关性分析表明,杭州湾北岸大气存在老化现象,异戊烷和正戊烷受煤燃烧源影响较大,二甲苯和乙苯受溶剂排放源影响较大,甲苯和苯除受机动车尾气影响外,还受其他排放源影响.④PMF和CPF模型来源分析表明,大气VOCs主要来自石化工业源、燃料挥发源、生物质燃烧和煤燃烧源、机动车排放源和溶剂使用源,其中,机动车排放源主要来自西北方向,其他源主要来自西北、西和西南方向.研究显示,杭州湾北岸大气VOCs来源复杂,受周边工业区的影响较大.