PFU微型生物群落水质鉴别及群落参数变化模式的研究

基于ＰＦＵ微型生物群落参数调查数据，对湖北省汉江两条污染带１１个站 和湖南常德市水系１５个站点所属水质组别进行了综合分析研究。所得典型鉴别函数能够对水质组别作出有效的鉴别，分类函数对站点的水质组别分类正确率达到９６％；群落参数对化学综合污染指数的响应不呈简单的线性关系，群落的变化存在一定模式。     

ANALYZING CORRELATIONS BETWEEN STREAM AND WATERSHED ATTRIBUTES1

ABSTRACT: Bivariate correlation analysis has been widely used to explore relationships between stream and watershed attributes that have all been measured on the same set of watersheds or sampling locations. Researchers routinely test H₀: ρ= 0 for each correlation in a large table and then go on to discuss only those that are declared “significant.” Such test results are inaccurate because no allowance is made for multiple testing, and also because the tests are not mutually independent. This paper reviews the Bonferroni approach to controlling the overall error rate in multiple testing and shows how the approach becomes impractical for large correlation tables. The Hotelling/Williams test is introduced for comparing two dependent correlations that share a variable, and numerical constraints for two such correlations are illustrated. References are also given for testing other hypothesized patterns among dependent correlations, and links to dependent correlation software are provided. The methods are illustrated for watershed and stream variables sampled in 23 small agricultural watersheds of the Willamette Valley, Oregon.     

池火灾热辐射的数值研究

通过列举储罐火灾事故,提出对池火灾进行研究的重要性。介绍目前池火灾国内外的研究现状及发展情况,描述池火灾燃烧特征和模型。应用化学流体力学基本定律,建立了描述池火灾过程的基本控制方程组,并根据适当的条件选择辐射模型。建立物理模型,做出合理假设,确定初始和边界条件,对池火灾热辐射过程进行数值模拟,得出火焰周围入射热流密度分布图,计算出相邻两罐之间的最小安全距离,应用于工程实际中,给防火间距的制定提供理论依据,计算结果定性合理。     

坡岸截留强化处理设施在不同运行条件下对农业面源污染物去除效果

对坡岸截留强化处理设施在不同温度、不同雨强、不同降雨间隔条件下处理农业面源污染进行中试试验研究.结果表明,水温从20℃下降至4.3℃,COD、TN、NH+4-N、TP去除率下降了15.58%、48.93%、42.26%、57.75%;降雨强度由0.65mm·min-1增加1倍至1.30 mm·min-1,COD的平均去除率低了15.19%,TN、NH+4-N的去除效率相当,TP的去除效率提高了11.21%,但COD、TN、NH+4-N、TP单位面积去除的总量却提高了26.27%、68.3%、32.6%、104.2%;降雨间隔从2 d增加到4 d时对COD去除的影响不大,但使NH+4-N、TN的处理效率提高19.31%、13.95%,对TP的单位面积去除量提高71.43%,但去除总量有限.     

Time allocation between work and recreation and the associated injury risks among young people

PROBLEM: The purpose of this study was to examine the relationship between overall risk of injury and time use patterns between work and active recreation among adolescents and young adults. METHODS: Using a representative sample of 9,795 Canadians aged 15-24 years, a multivariate logistic regression on the likelihood of any medically attended injury was conducted, including sociodemographic, individual, and time factors. RESULTS: Young people who engaged in a combination of high work and high activity hours were twice as likely to sustain a medically attended injury compared to those who worked low hours, but did not participate in any recreational activity. Those respondents who were not in school had a 43% increase in injury risk compared to full-time students. SUMMARY: Our findings suggest that injury risk was not a simple function of fatigue and cumulative exposure time. Our findings suggest the importance of considering time use and the associated injury risk tradeoffs. IMPACT ON INDUSTRY: Relevant to state and federal work safety policy makers, our findings suggest the importance of understanding where youth might otherwise spend their time if constraint were placed on their employment opportunities, and the associated injury risk tradeoffs must be taken into consideration.     

基于均匀分布的滑坡数值模拟参数取值概率研究--以甘肃黑方台黄土滑坡为例

针对数值模拟参数选取主观性强、量化难度大的问题,在高精度无人机地形数据的基础上,通过对11起滑坡案例进行了407组参数反演实验,对结果准确度定量评价后,得到基于Massflow数值软件关键参数λ0的分布范围,进而运用小样本极大似然估计理论,分析区间边界长度对反演精度的影响,最终提出基于均匀分布的参数取值概率模型,并选用案例验证该模型的准确性。结果表明:地形约束会导致反演过程中所需的内聚力减小,反演获得的11组最优λ0的极差和方差分别为0.29、0.01,在置信度为95%下,极大似然法得到区间边界估计长度仅为0.0998,表明参数λ收敛性较好;反演过程中质心滑动距离ψ准确度优于堆积面积重叠率η,在λ0±0.05的范围,参数估计区间内任意值对模拟误差影响较小,评价指标ψ、η与λ0对应案例的相对误差不超过15%;所选案例验证了在置信度为95%下,以反演得到的最优参数区间边界中点构建概率分布函数的可行性和准确性,研究方法可为单体滑坡数值模拟风险评价提供理论支撑。     

Costs and benefits of improving wild salmon passage in a regulated river

This paper presents a cost-benefit analysis (CBA) of a trade-off between salmon and hydropower production in the Ume/Vindel River, northern Sweden. A distinctive element of this analysis is that estimated changes in resource conditions are based on detailed river-specific data. A salmon population model was used to develop the scenario and a novel willingness to pay (WTP) question, which caters for uncertainty in a different manner, provided an interval estimate. Non-use values are the major contributors to the benefit (96–517 millions of Swedish kronor (MSEK)) of increasing the stock of wild salmon. Sensitivity analysis suggests that the opportunity costs in terms of lost electricity are typically higher than the estimated benefits.     

Parental phenols exposure and spontaneous abortion in Chinese population residing in the middle and lower reaches of the Yangtze River

Widespread use of phenols has led to ubiquitous exposure to phenols. In experimental animals, phenols increased resorptions, reduced live litter size and fetal body weights. However, there are limited epidemiological evidences of the relationships between exposure to phenols and pregnancy outcomes. We evaluated the associations between parental urinary levels of various phenols and spontaneous abortion in a Chinese population residing in the middle and lower reaches of the Yangtze River. A case-control study was conducted that included 70 case couples with medically unexplained spontaneous abortion and 180 control couples who did not have a history of spontaneous abortion and had at least one living child. Both parental urinary phenols were measured by ultra-high performance liquid chromatography-tandem mass spectrometry including bisphenol A (BPA), benzophenone-3 (BP-3), 2,3,4-trichlorophenol (2,3,4-TCP), pentachlorophenol (PCP), 4-n-octylphenol (4-n-OP) and 4-n-nonylphenol (4-n-NP). Compared with the low exposure group, there was an increased risk of spontaneous abortion with high paternal urinary PCP concentration [odds ratio (OR) = 2.09, 95% Confidence Interval (CI), 1.05–4.14], and maternal exposure to 4-n-OP and alkylphenol(s) also significantly increased the risk of spontaneous abortion (OR = 2.21, 95% CI, 1.02–4.80; OR = 2.81, 95% CI, 1.39–5.65, respectively). Our study firstly provides the evidence that paternal PCP exposure, maternal 4-n-OP and alkylphenol(s) exposure are associated with spontaneous abortion in humans.     

Reversed association between levels of prostate specific antigen and levels of blood cadmium and urinary cadmium

Prostate cancer associated with cadmium exposure may indicate a link between prostate specific antigen (PSA) and levels of blood cadmium (BCd) and urinary cadmium (UCd). Thus, these associations were investigated. We recruited 295 men, 50 years of age and above from a health check-up program at a health center as subjects of the study. They completed a self-reported questionnaire and provided fasting samples of blood and urine for cadmium assay. The assay was performed using atomic absorption spectrophotometry. Blood samples were also collected for the assays of total cholesterol and high-density lipoprotein measures. The means of BCd and UCd increased with age and the means of all subjects were 1.19 ± 1.04 μg L⁻¹ and 1.37 ± 1.76 μg g⁻¹ creatinine, respectively. The PSA levels were positively associated with the lipid levels, but reversely associated with BCd and UCd levels. The multivariate logistic regression analysis showed that men with PSA ? 4.0 ng mL⁻¹ had an odds ratio (OR) of 0.4 (95% CI = 0.1-0.9) to have BCd > 0.49 μg L⁻¹, and an OR of 0.4 (95% CI = 0.2-1.0) to have UCd > 0.45 μg g⁻¹ creatinine. In conclusion, the PSA levels are reversely associated with BCd and UCd levels.     

一种灾害等级的区间数评估模型

由于灾害损失本身的复杂性及灾情统计方面存在的问题,利用区间数替代单一实数值作为灾害等级评估指标的输入更加符合实际。基于上述思路,提出了一种基于区间数的灾害等级评估新模型。首先,给出区间数距离的新定义,该定义能够充分利用区间数所携带的信息;然后,利用线性加权评价函数计算评估对象与评价标准之间的综合相对距离测度,评估对象隶属于综合距离测度最小值所对应的灾害等级。该模型建模过程思路清晰,物理意义明确,计算过程简捷,评估结论符合实际。最后,用实例说明模型的应用方法。