Safety Level of Acrobatic Work: A Probabilistic Study

Acrobatic work constitutes an activity during which individuals intervene on buildings, cliffs, towers, and so forth, through the use of mountaineering or speleological techniques. The most dangerous situations occur particularly when ascending a rope with ascenders or roping with a descender. Any free fall or false manoeuvre will result in a strong shock on the belaying system that may cause its rupture. The fatal accident rate (FAR) of a given occupation is defined as the average number of fatal accidents per 10⁸ hrs of exposure to a given hazard. In this study it is assumed that the FAR is proportional to the average number of fall-initiating events, η, per worker and per hour of exposure to the fall hazard. η is estimated to be between 10^-3 and 3 × 10^-3. The maximum values of the rupture probability of the securing systems are calculated for the FAR of acrobatic work to be smaller than the FAR of the three most dangerous activity groups of the construction industry in France. These values allow the varying ranges of the parameters that influence this rupture probability to be determined.     

A discourse-analytical perspective on sustainability assessment: interpreting sustainable development in practice

Sustainable development is a ubiquitously used concept in public decision-making: it refers to an ideal vision of global society where human development and environmental quality go hand in hand. Logically, any decision-supporting process aiming at facilitating and steering society toward a sustainable future then seems desirable. Assessing the sustainability of policy decisions is, however, influenced by what sustainable development is believed to entail, as different discourses coexist under the umbrella of the sustainable development meta-discourse. This paper proposes a typology of sustainable development discourses, and, subsequently, applies a discourse-analytical lens on two practical cases of sustainability assessment in different institutional and geographical contexts (in Belgium and in Benin). The results indicate that sustainability assessments tend to be influenced mainly by the consensual ‘sustainable development as integration’ discourse, while also providing a forum for dialogue between different discourses. The results shed light on context-specific discursive and institutional dynamics for the development and application of sustainability assessment. Acknowledging these dynamics as well as sustainable development’s inherent interpretational limits can lead to an improved use of sustainable development as a decision-guiding strategy.     

Soil Vapor Extraction and Chemical Oxidation to Remediate Chlorinated Solvents in Fractured Crystalline Bedrock: Pilot Study Results and Lessons Learned

A pilot study was completed at a fractured crystalline bedrock site using a combination of soil vapor extraction (SVE) and in‐situ chemical oxidation (ISCO) with Fenton's Reagent. This system was designed to destroy 1,1,1‐trichloroethane (TCA) and its daughter products, 1,1‐dichloroethene (DCE) and 1,1‐dichloroethane (DCA). Approximately 150 pounds of volatile organic compounds (VOCs) were oxidized in‐situ or removed from the aquifer as vapor during the pilot study. Largely as a result of chemical oxidation, TCA concentrations in groundwater located within a local groundwater mound decreased by 69 to 95 percent. No significant rebound in VOC concentration was observed in these wells. Wells located outside of the groundwater mound showed less dramatic decreases in VOC concentration, and the data show that vapor stripping and short‐term groundwater migration following the oxidant injection were the key processes at these wells. Although the porosity of the aquifer at the site is on the order of 2 percent or less, the pilot study showed that SVE could be an effective remedial process in fractured crystalline rock. © 2002 Wiley Periodicals, Inc.     

Prenatal diagnosis of molybdenum cofactor deficiency and isolated sulfite oxidase deficiency

Molybdenum cofactor deficiency and isolated sulfite oxidase deficiency are autosomal recessive inborn errors of metabolism with severe neurological symptoms resulting from a lack of sulfite oxidase activity. The deficiencies can be diagnosed prenatally by monitoring sulfite oxidase activity in chorionic villus sampling (CVS) tissue. In those families in which the specific defects have been identified, diagnosis can be achieved by mutation analysis or linkage studies directed at affected genes. These include MOCS1, MOCS2 or GEPH, in cases of molybdenum cofactor deficiency, or SUOX in patients with isolated sulfite oxidase deficiency. Copyright © 2002 John Wiley & Sons, Ltd.     

PREDICTIVE REAL TIME CONTROL OF SURCHARGED INTERCEPTORS: IMPACT OF SEVERAL CONTROL PARAMETERS1

ABSTRACT: A global predictive real time control strategy minimizing overflow volumes from combined sewers during rainfall was applied to control flows entering the Marigot interceptor (Laval, Canada) for 23 rain events that occurred in this urban area during the summer of 1989. Different surcharge intensities were allowed in the sewer. The duration of the control horizon as well as the location and number of control regulators were varied to assess the impact of these parameters on total overflow volumes and on control safety. Due to the high propagation speed of flow waves in pressurized conduits, it was found that five‐ minute control horizons were sufficient to ensure control performance and safety when important surcharges were permitted in the interceptor and when the controlled regulators were located where pressurized flow occurred. It was also found that it is possible to reduce the number of controlled regulators by placing them at locations intercepting the largest volumes of water during rain periods.     

Relatedness and environment affect traits associated with invasive and noninvasive introduced Commelinaceae.

Understanding the traits of invasive species may improve the ability to predict, prevent, and manage invasions. I compared morphological and performance traits of five congeneric pairs of invasive and noninvasive Commelinaceae across a factorial experiment using a range of water and nutrient availabilities. Invasive species had greater fecundity and vegetative reproduction than their noninvasive relatives. The invasive species also had higher relative growth rates, greater specific leaf area, and more plastic root-to-shoot ratios than noninvasive species. However, whether a trait was associated with invasiveness often depended on both environment and relatedness. Invasives had greater sexual and vegetative reproduction, higher specific leaf area, and greater relative growth rates than noninvasive congeners, but only in some environments. Differences between invasive and noninvasive taxa were greatest at high nutrient availabilities. These results suggest that studies of invasive species' traits must incorporate information on conditions under which the trait was measured. In addition, incorporating information on relatedness improved our ability to detect associations between species traits, such as specific leaf area and relative growth rate, and invasiveness, suggesting that such information may be required for a complete understanding of what makes a species invasive.     

添加生物炭对西北黄土吸附克百威的影响

研究了不同温度下制得的生物炭对西北黄土吸附农药克百威的影响,并对溶液p H值和初始浓度对吸附的影响进行了探讨.结果表明,克百威在添加生物炭黄土上的动力学吸附过程较好地符合准二级吸附动力学模型;热力学吸附较好地符合Freundlich等温吸附模型;随着系统温度的升高,添加生物炭的黄土对克百威的吸附量增大,且其对克百威的吸附自由能变(ΔGθ)小于0,吸附焓变(ΔHθ)及吸附熵变(ΔSθ)均大于0,表明吸附是一个自发吸热且体系混乱程度增大的等温吸附过程.溶液p H值和克百威的初始浓度对添加生物炭的土样吸附影响较明显.当p H值为4~7时,添加生物炭的土样饱和吸附量随p H升高呈缓慢降低,当p H值大于7时,吸附容量随p H升高呈明显降低趋势.克百威初始浓度从20 mg·L-1增至50 mg·L-1的过程中,吸附量快速上升,初始浓度大于50 mg·L-1时,吸附量随初始浓度的升高而缓慢增加并逐渐趋于平衡.     

我国西北黄土对阿特拉津的吸附行为及影响因素

为了探讨ATZ(阿特拉津)在黄土中的吸附/解吸行为及主要影响因素,以我国西北黄土为供试土样,采用批量试验法研究了黄土对ATZ的吸附动力学和热力学行为特征. 结果表明:黄土对ATZ的吸附动力学过程更符合准二级动力学模型,吸附热力学过程更符合线性分配的Henry吸附模型(R2>0.90),吸附过程中ΔGθ(吉布斯自由能)及ΔHθ(焓变)均小于0、ΔSθ(熵变)大于0,25～45 ℃温度范围内E(吸附平均自由能)为0.86～1.30 kJ/mol,表明黄土对ATZ的吸附过程以物理吸附为主,属于自发放热过程且导致吸附体系混乱度增加. 黄土对ATZ的吸附影响因素分析结果显示,随着系统温度的升高,ATZ在黄土中的饱和吸附量下降;pH在2～10范围内变化时,ATZ在黄土中的饱和吸附量随pH的增加呈明显降低趋势;初始ρ(ATZ)从2.5 mg/L增至10.0 mg/L时,黄土对ATZ的饱和吸附量也相应地从0.082 5 mg/g增至0.621 0 mg/g. 结果显示,ATZ在黄土中的吸附速率受内部扩散、表面吸附和液膜扩散的共同影响,并且吸附过程主要受到土壤有机质疏水性分配作用的影响.