气温与湿度的交互作用对呼吸系统疾病的影响

为评价平均气温、相对湿度及其交互作用对呼吸系统疾病急诊就诊人数的影响,采用广义相加模型(GAM),在控制了时间长期趋势、"星期几效应"、节假日效应、空气污染等因素的影响后,分析2009~2011年北京市平均气温、相对湿度及其交互作用对呼吸系统疾病急诊就诊人数影响的暴露反应关系.结果显示,平均气温与呼吸系统疾病急诊就诊人数呈现近似U型的非线性关系,其作用临界点为12℃,当平均气温低于12℃时,气温每升高1℃,呼吸系统疾病急诊就诊人数减少2.26%(95%CI-2.43,-2.09);当气温高于12℃时,气温每升高1℃,呼吸系统疾病急诊就诊人数增加0.92%(95%CI 0.72, 1.11).相对湿度与呼吸系统疾病的效应也呈现U型的分布特征,作用阈值为51%,当相对湿度≤51%时,相对湿度每增加10%,呼吸系统疾病急诊就诊人数减少3.43%(95%CI -3.47%,-3.38%);当相对湿度>51%时,其每增加10%呼吸系统疾病急诊就诊人数增加1.80%(95%CI 1.76%,1.85%).平均气温对呼吸系统疾病的影响受相对湿度水平的调节.在低温环境下,相对湿度越小,气温对呼吸系统疾病的影响越显著,气温每升高1℃,呼吸系统疾病急诊就诊人数减少2.71%(95%CI -2.88,-2.53);;而高温环境下,当相对湿度较大时气温健康效应较强,即气温每升高1℃,呼吸系统疾病急诊就诊人数增加1.37%(95%CI 1.13, 1.61).     

Influence of cadmium on the storage and metabolism of HCH in rats

Male albino rats were administered Cd and HCH daily for six weeks to study the effect of Cd on storage and metabolism of HCH. The results indicated a marked inhibition of the metabolism of HCH in the group dosed with HCH + Cd. The metabolic rate of HCH in the group dosed with HCH + Cd was also significantly lower than that in the group dosed with HCH alone. The hepatic content of Cd and Zn was significantly increased whereas a marked depletion of Cu and Fe was observed in the groups exposed to Cd and HCH + Cd. A high level of free Cd and Zn or a low level of Fe and Cu in liver seemed to play an important role in the metabolic inhibition observed in this study.     

氮素影响陆地生态系统碳循环过程的模型表达方法

氮素是植物生长所必需的重要营养元素。人类活动引起的大气氮沉降增加对陆地生态系统碳循环过程具有重要影响。准确地定量表达氮素对陆地生态系统碳循环过程的影响是预测未来全球碳循环变化的关键环节。论文系统地归纳总结了国内外多个知名生物地球化学模型中氮素影响光合作用、呼吸作用、同化物分配等碳循环过程的数学表达方法,分析了不同碳循环过程中模型表达方法的不确定性及其原因。指出未来模型的发展需在加强机理研究的基础上,发展能反映氮饱和现象、能显式表达氮素与光合速率关系的光合作用过程算法,发展能显式表达氮素与植物体根、茎和叶呼吸速率关系的维持呼吸算法以及发展显式表达氮素对同化物分配过程影响的动态同化物分配方案。指出当今大部分主流模型在模拟氮素对光合作用影响时没有考虑氮饱和现象,因此利用模型预测未来陆地生态系统对氮素增加的响应时可能会高估氮沉降对光合速率的影响。研究综述可为准确评价陆地生态系统碳氮相互作用和发展碳氮耦合模型提供参考。     

Tornadoes,television and trust—A closer look at the influence of the local weathercaster during severe weather

Previous research has acknowledged the importance of mass media in shaping risk perception and as the channel through which people get information during and after disasters. There is still much more to know about the role mass media (but especially the television medium) plays in people's precautionary hazard behaviors. Close to 400 people were surveyed in the Memphis, TN television market about their knowledge and perception of the severe weather threat, and their past experiences with tornadoes and severe thunderstorms.The survey results show that respondents do develop a relationship with their local television weathercaster and also trust their weathercaster during severe weather. This relationship and trust can then predict the likelihood of taking shelter during severe weather. Ultimately, the case will be made that the findings may be useful to future hazards research in other locations.     

砷-铅交互作用对水稻根表铁膜富集及根系吸收砷铅的影响

采用土-砂联合培养方法诱导水稻根表自然形成铁氧化物膜,研究了As-Pb交互作用对水稻根表铁膜吸附砷铅及根系吸收As和Pb的影响.结果表明,As和Pb的添加显著地影响水稻根表铁膜对As和Pb的吸附,并且As-Pb交互作用显著地影响水稻根系对两元素的吸收及根表铁膜对As的吸附.添加Pb可促进水稻根系对As的吸收.当As浓度为25μmol.L-1时,浓度为25μmol.L-1Pb处理与对照相比导致水稻根系吸收As提高了53.3%.同样,施用As也可以促进水稻根系对Pb的吸收,当Pb的浓度为25μmol.L-1和50μmol.L-1时,50μmol.L-1As处理与对照相比,水稻根系吸收Pb分别提高20.2%和28.6%.添加As显著地促进Pb由铁膜向根系中转运,而添加Pb对As由铁膜向根系中的转运影响不大.因此,在重金属复合污染情况下,水稻根表铁膜对重金属的吸附及根系对重金属的吸收均存在着复杂的交互作用.     

茄科雷尔氏菌蛋白质相互作用网络预测及分析

细菌性青枯病是由茄科雷尔氏菌(Ralstonia solanacearum)引起的一种世界范围的细菌性土传病害.该细菌基因组序列的完全测序,使得从蛋白质组角度来分析其蛋白质相互作用网络成为可能.本文通过朴素贝叶斯模型整合系统发生谱法、基因邻近法、基因融合法、操纵子法、同源映射法、微阵列法、域相互作用法等7种方法,并根据约豋指数确定的阙值,预测了可信的茄科雷尔氏菌的蛋白质相互作用网络.对网络中的分泌子网络和信号转导进行了分析,提出可能的药物作用靶点(cyaB、pilD、Fli、Rsp1526、VsrA、VsrB、PilH).对于未注释的蛋白依据蛋白相互作用推测了部分蛋白质的功能.本文也提供了完全免费的在线数据库支持,提供了方便的茄科雷尔氏菌的蛋白相互作用的查询及相互作用数据和推测的蛋白质功能数据的查询和下载(http://www.scbmp.org.cn/rsoppi.php).     

强力霉素在凹凸棒土上的吸附行为

通过等温吸附平衡法研究了强力霉素在凹凸棒土上的吸附行为,考察了pH、反应时间、离子强度和离子类型等因素对吸附的影响,探讨了吸附机理.结果表明,pH=8.5时,饱和吸附容量最大,为293.35μmol.g-1;强力霉素在凹凸棒土上的吸附可用Langmuir型等温方程和准二级动力学方程很好地拟合;离子强度对强力霉素的吸附影响不是很明显;0.05 mol.L-1NaOH能显著地将强力霉素从凹凸棒土上解吸下来.红外表征结果说明凹凸棒土对强力霉素的吸附可能是化学吸附,酸性条件下,强力霉素主要通过阳离子交换、静电作用、氢键作用等吸附在凹凸棒土上,部分H+可能通过强力霉素质子化吸附到凹凸棒土上.弱碱性条件下主要通过水桥接,与凹凸棒土层间阳离子配位以及结合于凹凸棒土边缘吸附位点达到吸附.     

A simple Lagrangian model to simulate temporal variability of algae in the Elbe River

We present a five-year (1997–2001) numerical simulation of daily mean chlorophyll a concentrations at station Geesthacht Weir on the lower Elbe River (Germany) using an extremely simple Lagrangian model driven by (a) water discharge, global radiation, water temperature, and (b) silica observations at station Schmilka in the upper reach of the Elbe River. Notwithstanding the lack of many mechanistic details, the model is able to reproduce observed chlorophyll a variability surprisingly well, including a number of sharp valleys and ascents/descents in the observed time series. The model's success is based on the assumption of three key effects: prevailing light conditions, sporadic limitation of algal growth due to lack of silica and algae loss rates that increase above an empirically specified temperature threshold of 20 °C. Trimmed-down model versions are studied to analyse the model's success in terms of these mechanisms.In each of the five years the model consistently fails, however, to properly simulate characteristic steep increases of chlorophyll a concentrations after pronounced spring minima. Curing this model deficiency by global model re-calibration was found to be impossible. However, suspension of silica consumption by algae for up to 10 days in spring is shown to serve as a successful placeholder for processes that are disregarded in the model but apparently play an important role in the distinctly marked period of model failure. For the remainder of the year the very simple model was found to be adequate.     

A resource-based approach to modelling the dynamics of interacting populations

The procedure for modelling the growth of single-species populations [Sakanoue, S., 2007. Extended logistic model for growth of single-species populations. Ecol. Model. 205, 159–168] is improved to be applicable to the study of the dynamics of interacting populations. The improved procedure is based on three assumptions: resource availability changes with population size as a variable, resource supply to populations and population demand for resources are defined as functions of resource availability and population size, and the variables of resource availability and population size shift in the supply function attracted to the demand function. These assumptions are organized into three equations. The equations can generate the dynamics models of plant, herbivore, and detritivore populations, and their own resources. The models can be used to describe prey–predator dynamics. They naturally contain nonlinear terms for the predator’s numerical and functional responses. Depending on the terms, the fluctuations in resource availability and population size stabilize. The three equations can also generate the dynamics models of different populations consuming the same resources. The analysis of zero isoclines of the models shows that a superior population can be simply defined as one with a higher intrinsic rate of natural increase, that a stable coexistence may be realized with the intraspecific interference or the interspecific facilitation of superiors, and that the interspecific interference or the intraspecific facilitation of inferiors may make the coexistence unstable and the inferiors winners depending on their initial population size.