中国黄土地区耕作侵蚀模拟

耕作侵蚀是国际上新近开展的一个研究领域。为了对中国黄土地区的耕作侵蚀规律进行定量描述,采用施放小立方块作为示踪材料进行耕作试验及测量来示踪和监测土壤运动,并通过相关分析与理论推导,对该地区的耕作侵蚀进行了模拟,获得了能够直接计算出坡面剖面任何一点净侵蚀模数的耕作侵蚀模型,结果表明,在采用当地由动物牵引的传统犁在坡面上自下而上进行往返横坡等高向下翻土耕作方式下:1)一次耕作导致的耕层土壤朝坡向方向平均水平运动距离随坡度的变化表现为线性相关;2)一次耕作导致的坡面剖面任何位置耕层断面的净侵蚀模数,受土壤容重、耕作深度、土壤与耕作条件决定的系数和地形曲率的影响。     

马尾松树皮提取物体外抑制人大肠癌细胞生长规律初探

为深入研究马尾松树皮提取物(PMBE)的抑癌生长作用,构建PMBE的动物药理模型,本研究通过细胞培养、细胞活力检测(MTT实验)及计算机模拟评估马尾松树皮提取物(PMBE)抑制体外培养人大肠癌LoVo细胞生长规律,建立了马尾松树皮提取物(PMBE)、胎牛血清(FBS)及处理时间(t)三因素对LoVo细胞生长抑制率的反应模型,利用该回归模型对三因素优化组合,同时就各因素单独效应及其互作效应进行了探讨。PMBE、FBS、t三因素适量水平搭配(0、1、0)可提高对LoVo的生长抑制效率,最高可达0.42,即三因子用量分别为140μg/mL、15%、48 h时效果最佳。系列数据分析结果表明,在体外处理细胞过程中可能存在抑制物效应报酬递减规律,且试验体系中多因素综合效应呈现随机非线性特点。该研究是统计学在医学科研设计、衡量和评价(D.M.E)领域的一次尝试,可为构建PMBE的动物药理模型确定药用剂量提供参考。     

The price of the precautionary principle: Cost-effectiveness of BSE intervention strategies in the Netherlands

Since 1996, bovine spongiform encephalopathy (BSE) in cattle has been linked to a new variant of Creutzfeldt-Jakob disease (vCJD), a fatal brain disease in man. This paper assessed the cost-effectiveness of BSE control strategies instituted by the European Commission. In a Monte Carlo simulation model, a non-intervention baseline scenario was compared to three intervention strategies: removal of specified risk materials from slaughter animals, post-mortem testing for BSE and the culling of feed and age cohorts of BSE cases. The food risk in the baseline scenario ranged from 16.98 lost life years in 2002 to 2.69 lost life years in 2005. Removing specified risk materials removal practices, post-mortem testing and post-mortem testing plus cohort culling reduced this risk with 93%, 82.7% and 83.1%. The estimated cost-effectiveness of all BSE measures in the Netherlands ranged from 4.3 million euros per life year saved in 2002 to 17.7 million euros in 2005. It was discussed that the cost-effectiveness of BSE control strategies will further deviate from regular health economics thresholds as BSE prevalence and incidence declines.     

基于电子舌的料酒味觉特征辨识与定量分析

为探明电子舌对调味料酒生产工艺的判别能力和理化指标的预测能力,本研究采用电子舌和理化检测手段,结合不同统计方法,对54份料酒样品分别建立定性和定量分析模型。结果表明,应用主成分分析(PCA)可以区分不同生产工艺的料酒样品,第一主成分为鲜味,贡献率62.4%,第二主成分为酸味,贡献率33.2%;应用簇类独立软模式法(SIMCA)可以准确判别酿造料酒和配制料酒,各传感器区分能力(DP)>5,识别率达到100%;应用偏最小二乘法(PLS)将传感器信号与行标方法检测结果进行拟合,总酸、氨基酸态氮和食盐的验证集标准偏差与预测标准偏差的比值(RPD)分别为12.1、6.5和14.1,建立的模型效果良好,可进行准确的定标和预测;酒精度RPD值为2.7,也可进行定量分析,但模型稳定性较弱。本研究结果为应用电子舌对调味料酒进行品质区分和检测提供了理论和实践基础。     

基于不同分类方法的城市土壤碳氮定量关系模型的建立

以深圳城市中心城区绿地土壤为研究对象,对表层0～20cm 土壤理化性状进行了系统调查分析.在此基础上.按调查总体、土壤酸碱度类别、土壤质地类别和土地利用类别等不同角度,建立了土壤有机碳(SOC)、全氮(TN)、有效态氮(AN)相互之间的定量相关关系模型,并通过数据验证,对不同模型进行了筛选.结果表明,SOC、TN及AN含量之间均有密切的关系,尽管传统的总体线性关系模型可以表达SOC、TN、AN之间的关系,但通过土壤类别分类建立的模型更为准确.     

Competitive Scavenging of Trace Metals by HFO and HMO during Redox-driven Early Diagenesis of Ferromanganese Nodules (11 pp)

-  Dedicated to Prof. Dr. Ulrich Förstner on his 65th birthdayBackground   Surface complexation models (SCM) alone have yet less successfully reproduced sorption isotherms of hydrous manganese oxides (HMO). This is in part due to the fact that the HMO structure may vary with pH, and also because microbially formed natural HMO has an oxidation number O/Mn 〈 2, i.e. is of non-stoichiometrical composition. The former effect has often led to severe artefacts, such as an under-prediction of metal sequestration at low pH, and non-comparable pK and pHZPC values in literature. The latter effect is of particular importance for environments of varying redox conditions like sediments.Objectives   We propose therefore a new sorption model comprising of amphoteric site SCM, ion exchange due to permanent charge compensation, and solid solution formation, in order to comply at least in part with the redox complexity of HMO phases of stable birnessite- and buserite-type structures. Methods   The model is run by a new Gibbs energy minimization code which is shown to be particularly suitable for such a sorption continuum approach. Results and Discussion   Initial calibration of the model was performed by experimental literature data on simple laboratory systems. Thus parameterised, we simulated on the basis of available field data the effect of redox-driven dissolution of a ferromanganese nodule on the partitioning of metals between the interacting HMO, HFO, and marine water phases. Our scenario model suggests that significant fraction of Mn and other metals, probably 50% or more, may be recycled to water column from the surface of the ferromanganese nodule upon gradual development of the bottom water stagnation, except of Zn for which a by far stronger net retention was found.Conclusion and Outlook   Our model, even if only a first approximation, clearly shows that stagnation in the marine bottom water, once occurring, can drastically change primary element proxy records in ferromanganese nodules, smoothing out any anomalous patterns in the most recent record.     

Estimation of turnover and equilibrium of soil organic matter using a mathematical approach

The methods based on N uptake of aerial-plants, soil organic matter （SOM） dynamics, Jenny＇s equation, and actual measurement of long-term field experiments in Jiaxing, Quzhou, Huangyan and Hangzhou of Zhejiang Province, China were used to determine the organic mineralization rate being helpful in estimating the organic requirement for SOM equilibrium. The results showed that the estimated mineralization ratios of SOM for Jiaxing and Quzhou were, respectively, 0.0404 and 0.0508 based on N uptake of aerial-plants in non-fertilized plots; 0.0405 and 0.012 using SOM dynamics in non-fertilized plots; and 0.0413 and 0.0513 using the actual investigated data and Jenny＇s equation. With Jenny＇s equation, soil organic C balance in manure ＋ N-P-K plots was estimated at nearly 28.8 g kg^-1 for Jiaxing and 32.4 g kg^-1 for Quzhou with predicted SOM linearly related to the actual investigated values （r^2 = 0.9640 for Jiaxing and 0.8541 for Quzhou）. To maintain the SOM balance in the non-fertilized plots the recommended rate of organic materials was 3 000-6 600 kg ha^-1, and the relevant rates of farm yard manure （FYM） in the manure and N-P-K plots were estimated at 3 375 （dry） and 17670 kg ha^-1 （wet） for Jiaxing, 1845 （dry） and 6090 kg ha^-1 （wet） for Quzhou.     

A canopy budget model to assess atmospheric deposition from throughfall measurements

A canopy exchange model is presented which allows atmospheric deposition to be estimated from longterm throughfall and precipitation measurements. For a forest in the Netherlands, the combination of throughfall measurements and this model resulted in deposition estimates which were similar to deposition estimates derived from micrometeorological measurements and inferential modeling, deposition of NOy being the only exception. Unfortunately, several basic assumptions in the canopy exchange model are not properly evaluated, which up to now limits its application. Suggestions are made on how the model can be improved.     

细沟侵蚀动态过程模拟数学模型和有限元计算方法

建立了集中水流作用下均质土壤坡面上细沟侵蚀动态模拟数学模型。模型包括根据质量守恒原理推导而得到的变沟宽水流连续性方程和泥沙运移方程；根据动量守恒方程推得到的水流动力学方程；由紊流冲击分布概率来确定的土壤剥离方程；过量泥沙采用沉积的一阶沉积方程。模型还考虑了沟床形态、水流动力、土壤侵蚀与泥沙沉积形成相互依赖的反馈环，具有表达细沟的空间变化和时间演变的能力。给出了利用有限元方法对水动力学方程及泥沙运移连续方程进行顺序求解的数值计算公式以及模型数值求解的具体步骤。