Caveats for Causal Interpretations of Linear Regression Coefficients for Fine Particulate (PM2.5) Air Pollution Health Effects

Recent linear regression analyses have concluded that decreasing levels of fine particulate matter (PM2.5) air pollution have increased life expectancy in the United States. These findings have left unresolved questions about the causal relation between reductions in PM2.5 levels and changes in cause‐specific (especially, cardiovascular disease, CVD) mortality risks. Their robustness (e.g., sensitivity to deletion of a single data point) has also been questioned. We investigate these issues in the National Mortality and Morbidity Air Pollution Study database. Comparing changes in PM2.5 levels and cause‐specific mortality rates for elderly people in 24 cities between two periods separated by a decade (1987–1989 and 1999–2000) shows that reductions in PM2.5 were significantly associated with increases in respiratory mortality rates and with decreases in CVD mortality rates. CVD and all‐cause mortality risks fell equally for all months of the year over this period, but average PM2.5 levels increased significantly for winter months. This casts doubts on the causal interpretation that declines in PM2.5 over the decade caused reduced short‐term mortality risks. Nonlinear regression suggests that reduced or negative marginal health benefits are associated with reductions of PM2.5 below 1999–2000 levels (about 15 μg/m³). Such nonlinear relations imply that risk communication statements that project a constant incremental reduction in mortality risks per unit reduction in PM2.5 do not adequately reflect the realistic possibility of nonlinear exposure‐response relations and diminishing returns to further exposure reductions.     

室内灯具设计的艺术思考

灯具是日常生活中必不可少的,它既具有实用功能,又具有很强的装饰功能。如今有了科学技术的支持,灯具的发展更是日新月异,室内灯具设计就是要研究将灯具的实用功能、装饰功能与室内环境完美的结合。     

Siting Samplers to Minimize Expected Time to Detection

We present a probabilistic approach to designing an indoor sampler network for detecting an accidental or intentional chemical or biological release, and demonstrate it for a real building. In an earlier article, Sohn and Lorenzetti developed a proof of concept algorithm that assumed samplers could return measurements only slowly (on the order of hours). This led to optimal “detect to treat” architectures that maximize the probability of detecting a release. This article develops a more general approach and applies it to samplers that can return measurements relatively quickly (in minutes). This leads to optimal “detect to warn” architectures that minimize the expected time to detection. Using a model of a real, large, commercial building, we demonstrate the approach by optimizing networks against uncertain release locations, source terms, and sampler characteristics. Finally, we speculate on rules of thumb for general sampler placement.     

对空监视情报雷达宽带技术应用研究

对一种对空监视情报雷达采用宽带技术提高目标监视、跟踪性能进行了分析和仿真,研究了多径传播引起的分裂波瓣,其凹口以及峰值所在角度,并且对多频点的雷达威力进行了合成分析.结果表明,适当增加雷达系统带宽,可以大大减少由于多路径传播造成的波瓣分裂影响,进而比较显著地提高情报雷达的目标监视和跟踪性能.其结果对于要求具有自动检测和跟踪的对空情报雷达特别重要.     

个体清洁空气权何以可能——兼论环境权利的宪法表达

麦考密克和拉兹都曾经主张清洁空气不可能成为个体权利的客体。雷奥梅、沃尔德伦和马默却主张清洁空气可能成为个体权利的客体。首先，我们应该区分公共物品的“享用”和“生成”。其次，我们应该区分个体独立享用的公共物品和集体共同享用的公共物品。享用的非排他性和享用的集体性是两种不同的特征。公共物品的非排他性并不妨碍一部分公共物品可能成为个体权利的对象。个体能否独立享用某种公共物品，才是决定这种公共物品能否成为个体权利客体的关键。由于清洁空气等公共物品具有个体独立享用性，公民个体在理论上可能对清洁空气等公共物品享有权利。我们可以通过权利的利益理论论证个体环境权利的存在。因此，将环境权利写入宪法第二章“公民的基本权利和义务”并不存在理论上的难题。     

A Framework for Estimating the Adverse Health Effects of Contamination Events in Water Distribution Systems and its Application

Intentional or accidental releases of contaminants into a water distribution system (WDS) have the potential to cause significant adverse health effects among individuals consuming water from the system. A flexible analysis framework is presented here for estimating the magnitude of such potential effects and is applied using network models for 12 actual WDSs of varying sizes. Upper bounds are developed for the magnitude of adverse effects of contamination events in WDSs and evaluated using results from the 12 systems. These bounds can be applied in cases in which little system‐specific information is available. The combination of a detailed, network‐specific approach and a bounding approach allows consequence assessments to be performed for systems for which varying amounts of information are available and addresses important needs of individual utilities as well as regional or national assessments. The approach used in the analysis framework allows contaminant injections at any or all network nodes and uses models that (1) account for contaminant transport in the systems, including contaminant decay, and (2) provide estimates of ingested contaminant doses for the exposed population. The approach can be easily modified as better transport or exposure models become available. The methods presented here provide the ability to quantify or bound potential adverse effects of contamination events for a wide variety of possible contaminants and WDSs, including systems without a network model.     

Modeling Retrospective Attribution of Responsibility to Hazard‐Managing Institutions: An Example Involving a Food Contamination Incident

Perceptions of institutions that manage hazards are important because they can affect how the public responds to hazard events. Antecedents of trust judgments have received far more attention than antecedents of attributions of responsibility for hazard events. We build upon a model of retrospective attribution of responsibility to individuals to examine these relationships regarding five classes of institutions that bear responsibility for food safety: producers (e.g., farmers), processors (e.g., packaging firms), watchdogs (e.g., government agencies), sellers (e.g., supermarkets), and preparers (e.g., restaurants). A nationally representative sample of 1,200 American adults completed an Internet‐based survey in which a hypothetical scenario involving contamination of diverse foods with Salmonella served as the stimulus event. Perceived competence and good intentions of the institution moderately decreased attributions of responsibility. A stronger factor was whether an institution was deemed (potentially) aware of the contamination and free to act to prevent or mitigate it. Responsibility was rated higher the more aware and free the institution. This initial model for attributions of responsibility to impersonal institutions (as opposed to individual responsibility) merits further development.     

羽状流作用下的非等温空调射流运动研究

在传统非等温射流理论的基础上，考虑由室内热源形成的羽状气流对非等温空调射流的热浮升作用，建立数学模型，得到了在内热源作用下非等温射流运动轨迹方程表达式。同时对不同热源形式、热源大小以及热源位置对空调射流和室内热舒适性的影响进行了实验研究，并根据实验结果对热源与射流的相互作用进行了讨论。结果表明，室内热源的存在将明显改变空调射流的运动轨迹，影响室内热舒适性。     

红江橙黄龙病热治疗的研究

本试验通过对红江橙二年生带黄龙病的苗木进行50-54℃湿热空气脱毒处理，不仅完全杀死材体内的病原菌，使树体恢复健康，而且提高病苗处理后的成活率，使湿热空气处理这种有效的脱毒方法，大面积推广到生产中去．     

航空物流园区规划及设施布局研究

物流园区在我国是一个新生事物 ,物流园区设施的合理布局是物流园区规划的主要内容。目前 ,有关物流园区设施布局方面的研究较少 ,航空物流园区规划及设施布局方面的文献更是难以见到 ,几乎没有可参照的模式。文章从物流园区的主要功能出发 ,根据现代物流理念、航空物流的特点以及最优化方法 ,研究航空物流园区规划及设施布局的最优化